JP3792579B2 - Liquid crystal display - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an active matrix liquid crystal display device including a reflective pixel electrode and a transmissive pixel electrode.
[0002]
[Prior art]
Liquid crystal display devices are widely used in OA devices such as word processors and personal computers, portable information devices such as electronic notebooks, or camera-integrated VTRs equipped with a liquid crystal monitor, taking advantage of the thin and low power consumption characteristics. It is used. The direct-view liquid crystal display device includes a transmissive liquid crystal display device using a transparent conductive thin film such as ITO (Indium Tin Oxide) as a pixel electrode, and a reflective liquid crystal device using a reflective electrode such as a metal as a pixel electrode. There is a display device.
[0003]
The display mode used in the reflection type display device does not use a mode using a polarizing plate such as a TN (twisted nematic) mode and a STN (super twisted nematic) mode which are widely used at present and a polarizing plate. Therefore, a phase transition guest host mode capable of realizing bright display has been actively developed in recent years.
[0004]
The liquid crystal panel of the liquid crystal display device does not emit light itself, unlike a CRT (CRT) or EL (electroluminescence) display device. Therefore, in the case of a transmissive liquid crystal display device, a device having a fluorescent tube called a backlight is installed in the back, and display is performed by transmission of light from the backlight. In the case of a reflective liquid crystal display device, display is performed by reflecting incident light from the surroundings by the reflective electrode.
[0005]
Since the transmissive liquid crystal display device performs display using a backlight as described above, the transmissive liquid crystal display device can perform bright and high-contrast display without being greatly affected by ambient brightness. However, since the backlight usually occupies 50% or more of the total power consumption of the transmissive liquid crystal display device, the power consumption increases when the backlight is provided. Furthermore, when the ambient light is very bright, for example, under fine weather, the display light looks darker than the ambient light, and the visibility is lowered.
[0006]
On the other hand, the reflective liquid crystal display device does not require a backlight and can reduce power consumption. However, the brightness and contrast of the display are influenced by the usage environment such as the ambient brightness. When it is dark, there is a problem that the visibility is extremely lowered.
[0007]
In order to solve the above problems, Japanese Patent Application Laid-Open No. 7-333598 discloses a transmissive display by using a transflective film that reflects and transmits incident light at a certain reflectance and transmittance. A configuration is disclosed in which both the reflective display and the display are realized by a single liquid crystal panel.
[0008]
However, when the semi-transmissive reflective film is formed of a metal thin film, it is necessary to use a material having a large absorption coefficient. Therefore, internal absorption of incident light increases, and scattered light that is not used for display is generated. The light utilization efficiency deteriorates. Further, in order to obtain the same effect as the translucent film by controlling the reflectance and transmittance of one pixel, when forming a fine hole in the metal thin film, the structure of the metal thin film is too fine. Therefore, there is a problem that it is difficult to control and it is difficult to produce a film having uniform characteristics.
[0009]
In order to solve the above problems, Japanese Patent Application Laid-Open No. 11-101992 discloses a reflection region 26 made of a metal film and a transmission region 28 made of a transparent conductive film in the same pixel, as shown in FIG. There has been disclosed a liquid crystal display device that efficiently uses light and has excellent productivity. Further, in this liquid crystal display device, by changing the thickness of the liquid crystal between the reflective region and the transmissive region, the optical path lengths of the reflective region and the transmissive region are made uniform to increase the light use efficiency.
[0010]
[Problems to be solved by the invention]
However, in the conventional liquid crystal display device in which the reflection region (reflection pixel electrode) 26 made of a metal film and the transmission region (transmission pixel electrode) 28 made of a transparent conductive film are formed in the same pixel, as will be described later. Since the optimum counter voltage of the reflective region 26 and the optimum counter voltage of the transmissive region 28 are different from each other, a DC bias voltage is always applied to the liquid crystal layer by a deviation from each optimum counter voltage. The optimal counter voltage is a correction of the voltage of the counter electrode so that the absolute values of the positive potential and the negative potential applied to the liquid crystal layer are equal to prevent deterioration of the liquid crystal due to the application of a DC voltage. This is the counter electrode voltage at that time. Here, the reason why the optimum counter voltages are different from each other will be described.
[0011]
The drain voltage applied to the pixel electrodes in the regions 26 and 28 does not match the source voltage, and is shifted from the source voltage by ΔVd obtained by the following equation (1) at the moment when the gate is closed. .
[0012]
ΔVd = (ΔVg × Cgd / (Cgd + Clc + Ccs)) (1)
Note that the parasitic capacitance between the gate electrode and the drain electrode is Cgd, the capacitance of the liquid crystal layer is Clc, the capacitance (auxiliary capacitance) of the auxiliary capacitance element is Ccs, and the gate potential difference is ΔVg.
[0013]
In the conventional liquid crystal display device, since the liquid crystal thicknesses of the reflective region and the transmissive region are changed to be different, the capacitances Clc of the liquid crystal layer have different values. In the liquid crystal display device, the parasitic capacitance Cgd between the gate electrode and the drain electrode, the auxiliary capacitance Ccs, and the gate potential difference ΔVg are the same in the regions 26 and 28 due to the configuration of the liquid crystal device. Therefore, the shift values of the voltages in the reflective region 26 and the transmissive region 28 are different. Therefore, the optimum counter voltage of the reflection region 26 and the optimum counter voltage of the transmission region 28 are different.
[0014]
That is, as shown in FIGS. 14A to 14E, a gate signal in which the gate potential difference ΔVg (r) of the reflective pixel electrode 26 and the gate potential difference ΔVg (t) of the transmissive pixel electrode 28 are the same is input. Even so, the voltage shift amount (shift amount of the reflection pixel electrode 26) ΔVd (r) from the source signal voltage of the reflection pixel electrode potential and the voltage shift amount (transmission) of the transmission pixel electrode potential from the source signal voltage. Since the shift amount ΔVd (t) of the pixel electrode 28 for light is different, the optimum counter voltage Vo (r) of the pixel electrode 26 for reflection is different from the optimum counter voltage Vo (t) of the pixel electrode 28 for transmission. It becomes. Note that the gate potential differences ΔVg (r) · ΔVg (t) are respectively the high level voltages Vgh (r) · Vgh (t) of the gate signals and the low level voltages Vgl (r) · Vgl (t) of the gate signals. ).
[0015]
On the other hand, since the voltage of the counter electrode (not shown) cannot partially change the potential, the voltages of the counter electrode, the optimal counter voltage of the reflective region 26, and the optimal counter voltage of the transmissive region 28 are determined as follows. Cannot match at the same time. Therefore, the deviation between the voltage of the counter electrode and the optimum counter voltage of the reflection region 26 and / or the difference between the voltage of the counter electrode and the optimum counter voltage of the transmission region 28 is always applied as a DC bias voltage to the liquid crystal layer. It will be.
[0016]
For this reason, when used for a long period of time, it may cause display defects such as unevenness and haze. In particular, in a liquid crystal display device used as a mobile display device, a low-frequency driving method has been proposed in order to reduce power consumption. However, a deviation from each optimum counter voltage between the reflection region and the transmission region is caused by flicker. It becomes easier to perceive as (flicker), and it is also a cause of lowering the display quality.
[0017]
The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide an active matrix substrate that has high light use efficiency and enables high-quality display regardless of the state of ambient light. A liquid crystal display device is provided.
[0018]
[Means for Solving the Problems]
In order to solve the above problems, the liquid crystal display device of the present invention has a plurality of pixels arranged in a matrix having a reflective pixel electrode for performing a reflective display and a transmissive pixel electrode for performing a transmissive display. An electrode, an auxiliary capacitance element that holds the potential of the pixel electrode, a source wiring that supplies a source signal, a gate wiring that supplies a gate signal, and a source electrode, a gate electrode, and a drain electrode. An active matrix substrate having a switching element that is selected and applies a source signal to the pixel electrode, a counter substrate having a counter electrode facing the reflective pixel electrode and the transmissive pixel electrode, the active matrix substrate, and the In the liquid crystal display device including a liquid crystal layer formed between the counter substrate and the counter substrate, the switching element includes a first switch. The reflective pixel electrode is connected to the first gate line through the first switching element, and the transmissive pixel electrode is connected to the second switching element. The auxiliary capacitance element includes a reflection auxiliary capacitance element connected to the reflection pixel electrode and a transmission auxiliary capacitance element connected to the transmission pixel electrode. The amplitude of the gate signal input to the first gate wiring, the amplitude of the gate signal input to the second gate wiring, and the parasitic capacitance between the gate electrode and the drain electrode of the first switching element, , A parasitic capacitance between the gate electrode and the drain electrode of the second switching element, a capacitance of the liquid crystal layer between the reflective pixel electrode and the counter electrode, and the counter to the transmissive pixel electrode. The source signal voltage of the pixel electrode potential for reflection generated when the switching element is switched by the capacitance of the liquid crystal layer between the electrodes, the capacitance of the reflection auxiliary capacitance element, and the capacitance of the transmission auxiliary capacitance element And the voltage shift amount from the source signal voltage of the transmission pixel electrode potential is set to be the same.
[0019]
According to the invention, the reflection pixel electrode is connected to the first gate line through the first switching element. In addition, a reflection auxiliary capacitance element is connected to the reflection pixel electrode. On the other hand, the transmissive pixel electrode is connected to a second gate wiring through a second switching element. In addition, a transmissive auxiliary capacitance element is connected to the transmissive pixel electrode.
[0020]
Therefore, between the amplitude of the gate signal input to the first gate wiring, the amplitude of the gate signal input to the second gate wiring, and the gate electrode and the drain electrode of the first switching element. A parasitic capacitance, a parasitic capacitance between the gate electrode and the drain electrode of the second switching element, a capacitance of the liquid crystal layer between the reflection pixel electrode and the counter electrode, and a transmission pixel electrode The capacitance of the liquid crystal layer between the counter electrode, the capacitance of the reflection auxiliary capacitance element, and the capacitance of the transmission auxiliary capacitance element can be individually set.
[0021]
Here, at the time of switching of the switching element, more specifically, at the moment when the switching element is turned off, the parasitic capacitance between the gate electrode and the drain electrode of the switching element and the liquid crystal layer between the pixel electrode and the counter electrode are changed. The voltage applied to the pixel electrode is shifted from the source signal voltage by a voltage determined by the relationship between the capacitance, the capacitance of the auxiliary capacitive element, and the amplitude of the gate signal input to the gate wiring of the switching element. To do. That is, when an alternating rectangular wave is input to the source wiring, the rectangular wave is shifted in the voltage axis direction while the amplitude and phase of the rectangular wave remain the same.
[0022]
Also, the amount of voltage shift differs between the reflective pixel electrode and the transmissive pixel electrode. There are four reasons why the voltage shift amount is different.
[0023]
The first reason is that the reflective pixel electrode and the transmissive pixel electrode use different gate wirings, that is, the first gate wiring and the second gate wiring. This is because it is not necessary to make the amplitudes of the gate signals input to the same, and in this case, the amplitudes of the gate signals are different.
[0024]
The second reason is that since the reflective pixel electrode and the transmissive pixel electrode use different switching elements, that is, the first switching element and the second switching element, the gate electrode of each switching element is not necessarily used. This is because the parasitic capacitance between the drain electrode and the drain electrode does not match.
[0025]
The third reason is that the liquid crystal layer between the reflective pixel electrode and the counter electrode and the liquid crystal layer between the transmissive pixel electrode and the counter electrode have a thickness and an area of each liquid crystal layer. This is because the capacities of the liquid crystal layers do not match.
[0026]
The fourth reason is that the capacity of the reflection auxiliary capacitive element and the capacity of the transmission auxiliary capacitive element do not necessarily match due to the structure of the active matrix.
[0027]
Therefore, in the present invention, the parasitic capacitance between the gate electrode and the drain electrode of the switching element that determines the shift amount of the voltage, the capacitance of the liquid crystal layer between the pixel electrode and the counter electrode, and the auxiliary capacitance The capacitance of the element and the amplitude of the gate signal input to the gate wiring of the switching element are set separately for the reflection pixel electrode and the transmission pixel electrode, respectively, and the shift amount of the voltage is set to reflect the reflection. The pixel electrode for transmission and the pixel electrode for transmission are made the same.
[0028]
As a result, the voltage shift amounts of the reflective pixel electrode and the transmissive pixel electrode are the same, and a waveform signal having the same shift amount is obtained in the reflective pixel electrode and the transmissive pixel electrode.
[0029]
Therefore, the voltage on the central axis along the time axis of the voltage waveform in the pixel electrode for reflection and the pixel electrode for transmission after the shift can be set as the voltage of the counter electrode. As a result, the voltage of the central axis of the voltage waveform of the reflective pixel electrode, the voltage of the central axis of the voltage waveform of the transmissive pixel electrode, and the voltage of the counter electrode can be matched.
[0030]
For example, when an AC rectangular wave is input to the source wiring, the absolute value of the positive potential and the negative potential of the reflective pixel electrode with respect to the counter electrode becomes equal, and at the same time, the transmissive pixel electrode with respect to the counter electrode The absolute value of the plus potential and minus potential of the same is also equal. In the following, the optimum counter electrode voltage for the reflective pixel electrode and the transmissive pixel electrode, that is, the voltage on the central axis along the time axis for each of the above voltage waveforms, respectively, is the optimum for reflection. The counter voltage and the optimum counter voltage for transmission are used. Therefore, in the liquid crystal display device, since the amount of voltage shift is the same, the optimum counter voltage for reflection coincides with the optimum counter voltage for transmission.
[0031]
As described above, in the liquid crystal display device of the present invention, the voltage of the counter electrode becomes the optimal counter voltage for reflection and the optimal counter voltage for transmission. Therefore, if the optimum counter voltage for reflection is different from the optimum counter voltage for transmission, a voltage deviation from the counter electrode always occurs, but the liquid crystal display device of the present invention does not cause a deviation. Therefore, a phenomenon in which a deviation between the optimal counter voltage for reflection and / or transmission and the voltage of the counter electrode is always applied to the liquid crystal layer as a DC bias voltage does not occur.
[0032]
Therefore, in the liquid crystal display device of the present invention, it is possible to suppress the occurrence of display defects such as unevenness and haze that occur when the liquid crystal display device is used for a long time. Furthermore, the occurrence of flicker can be suppressed. On the other hand, the use efficiency of light is improved because the reflection pixel electrode and the transmission pixel electrode are used. Therefore, it is possible to provide a liquid crystal display device that has a high light use efficiency and enables high-quality display regardless of the state of ambient light.
[0033]
The liquid crystal display device of the present invention is the above liquid crystal display device, wherein the parasitic capacitance between the gate electrode and the drain electrode of the first switching element is Cgd (r), and between the reflective pixel electrode and the counter electrode. The capacitance of the liquid crystal layer is Clc (r), the capacitance of the reflection auxiliary capacitive element is Ccs (r), and the parasitic capacitance between the gate electrode and the drain electrode of the second switching element is Cgd (t). , The capacitance of the liquid crystal layer between the transmission pixel electrode and the counter electrode is Clc (t), and the capacitance of the transmission auxiliary capacitance element is Ccs (t), and the gate is input to the first gate wiring. ΔVg (r) × Cgd (r) / (Cgd (r) where ΔVg (r) is the amplitude of the signal and ΔVg (t) is the amplitude of the gate signal input to the second gate wiring. + Clc (r) + Ccs (r) = Is set to satisfy the ΔVg (t) × Cgd (t) / (Cgd (t) + Clc (t) + Ccs (t)) the relationship.
[0034]
According to the invention, in the following relational expression representing a general voltage shift amount ΔVd, ΔVd = ΔVg × Cgd / (Cgd + Clc + Ccs), the respective voltage shifts in the reflective pixel electrode and the transmissive pixel electrode. The value of the amount ΔVd becomes equal.
[0035]
Therefore, in the liquid crystal display device, the optimum counter voltage for reflection and the optimum counter voltage for transmission can be matched.
[0036]
The liquid crystal display device of the present invention is characterized in that the same gate signal is input to the first gate wiring and the second gate wiring in the above liquid crystal display device.
[0037]
According to the above invention, the same gate signal is input to the first gate wiring and the second gate wiring.
[0038]
Accordingly, it is not necessary to shift the phase of the gate signal from the first gate wiring and the phase of the gate signal from the second gate wiring, so that the gate signals are sequentially input with the phases shifted. The frequency of the gate signal can be halved. Therefore, it is possible to provide a liquid crystal display device that can enable high-quality display while reducing power consumption.
[0039]
In order to solve the above problems, the liquid crystal display device of the present invention has a plurality of pixels arranged in a matrix having a reflective pixel electrode for performing a reflective display and a transmissive pixel electrode for performing a transmissive display. An electrode, an auxiliary capacitance element that holds the potential of the pixel electrode, a source wiring that supplies a source signal, a gate wiring that supplies a gate signal, and a source electrode, a gate electrode, and a drain electrode. An active matrix substrate having a switching element that is selected and applies a source signal to the pixel electrode, a counter substrate having a counter electrode facing the reflective pixel electrode and the transmissive pixel electrode, the active matrix substrate, and the In the liquid crystal display device including a liquid crystal layer formed between the counter substrate and the counter substrate, the switching element includes a first switch. The reflective pixel electrode is connected to the first gate line through the first switching element, and the transmissive pixel electrode is connected to the second switching element. The auxiliary capacitance element includes a reflection auxiliary capacitance element connected to the reflection pixel electrode and a transmission auxiliary capacitance element connected to the transmission pixel electrode. Occurring at the time of switching of the first switching element and the second switching element, After the voltage shift from the source signal voltage of the reflection pixel electrode potential and the voltage shift from the source signal voltage of the transmission pixel electrode potential, on the time axis of the voltage waveform at the reflection pixel electrode and the transmission pixel electrode To match the voltage of the central axis along The source signal voltage applied to the reflective pixel electrode via the first switching element and the second switching element are synchronized with the display timings of the reflective pixel electrode and the transmissive pixel electrode, respectively. It is characterized in that the source signal voltage applied to the transmissive pixel electrode is different.
[0040]
According to the invention, the reflection pixel electrode is connected to the first gate line through the first switching element. On the other hand, the transmissive pixel electrode is connected to a second gate wiring through a second switching element. Therefore, the switching timing of each switching element can be varied. Also, Reflective pixel after a voltage shift from the source signal voltage of the pixel electrode potential for reflection and a voltage shift from the source signal voltage of the pixel electrode potential for transmission that occurs at the time of switching of the first switching element and the second switching element To match the voltage of the central axis along the time axis of the voltage waveform in the electrode and the transmission pixel electrode, The source signal voltage when the switching element connected to each pixel electrode is turned on is changed.
[0041]
Here, when the switching element is switched, more specifically, at the moment when the switching element is turned off, the voltage is shifted from the source signal voltage as described above. Also, the voltage shift amount differs between the reflective pixel electrode and the transmissive pixel electrode for the above four reasons.
[0042]
Therefore, in the present invention, the shift amount of each electrode is controlled in advance by controlling the voltage of the source voltage in consideration of the difference between the voltage shift amount of the reflection pixel electrode and the voltage shift amount of the transmission pixel electrode. Make the same.
[0043]
As a result, the voltage shift amounts of the reflective pixel electrode and the transmissive pixel electrode are the same, and a waveform signal having the same shift amount is obtained in the reflective pixel electrode and the transmissive pixel electrode.
[0044]
Therefore, as described above, the voltage of the central axis of the voltage waveform of the reflective pixel electrode, the voltage of the central axis of the voltage waveform of the transmissive pixel electrode, and the voltage of the counter electrode can be matched. Become.
[0045]
As described above, in the liquid crystal display device of the present invention, the voltage of the counter electrode can be set to the optimum counter voltage for reflection and the optimum counter voltage for transmission. Therefore, in the liquid crystal display device of the present invention, voltage deviation from the counter electrode does not occur.
[0046]
Therefore, in the liquid crystal display device of the present invention, it is possible to suppress the occurrence of display defects such as unevenness and haze that occur when the liquid crystal display device is used for a long time. Furthermore, the occurrence of flicker can be suppressed. On the other hand, the use efficiency of light is improved because the reflection pixel electrode and the transmission pixel electrode are used. Therefore, it is possible to provide a liquid crystal display device that has a high light use efficiency and enables high-quality display regardless of the state of ambient light.
[0047]
The liquid crystal display device of the present invention is the above liquid crystal display device, wherein the parasitic capacitance between the gate electrode and the drain electrode of the first switching element is Cgd (r), and between the reflective pixel electrode and the counter electrode. The capacitance of the liquid crystal layer is Clc (r), the capacitance of the reflection auxiliary capacitive element is Ccs (r), and the parasitic capacitance between the gate electrode and the drain electrode of the second switching element is Cgd (t). , The capacitance of the liquid crystal layer between the transmission pixel electrode and the counter electrode is Clc (t), and the capacitance of the transmission auxiliary capacitance element is Ccs (t), and the gate is input to the first gate wiring. When the amplitude of the signal is ΔVg (r) and the amplitude of the gate signal input to the second gate wiring is ΔVg (t), the source signal voltage applied to the reflection pixel electrode, Mark on transparent pixel electrode The difference ΔVs from the applied source signal voltage is ΔVs = ΔVg (r) × Cgd (r) / (Cgd (r) + Clc (r) + Ccs (r)) − ΔVg (t) × Cgd (t) / ( It is characterized by satisfying the relationship of Cgd (t) + Clc (t) + Ccs (t)).
[0048]
According to the above invention, the shift amount ΔVg (r) × Cgd (r) / (Cgd (r) + Clc (r) + Ccs (r)) of the voltage of the reflection pixel electrode and the voltage shift of the transmission pixel electrode. The difference between the amount ΔVg (t) × Cgd (t) / (Cgd (t) + Clc (t) + Ccs (t) is applied to the signal voltage of the source wiring applied to the reflection pixel electrode and the transmission pixel electrode. The source signal voltage is different.
[0049]
Therefore, the potential after the shift of the reflection pixel electrode and the potential after the shift of the transmission pixel electrode coincide with each other due to the difference ΔVs between the source signal voltages. Therefore, in the liquid crystal display device, the reflection optimum counter voltage and the transmission optimum counter voltage can be matched.
[0050]
In the liquid crystal display device of the present invention, in the above liquid crystal display device, the thickness of the liquid crystal layer between the transmission pixel electrode and the counter electrode is set to the thickness of the liquid crystal layer between the reflection pixel electrode and the counter electrode. It is characterized by being larger than this.
[0051]
According to the above invention, the optical path length of the ambient light passing back and forth through the liquid crystal layer corresponding to the reflective pixel electrode region and the liquid crystal layer corresponding to the transmissive pixel electrode region pass The optical path length of the transmitted light in the liquid crystal layer can be made closer.
[0052]
Therefore, it is possible to make uniform changes in the light characteristics of the liquid crystal layer corresponding to the reflective pixel electrode region and the liquid crystal layer corresponding to the transmissive pixel electrode region. Therefore, the light utilization efficiency can be further increased.
[0053]
In the liquid crystal display device of the present invention, in the above liquid crystal display device, the thickness of the liquid crystal layer between the transmission pixel electrode and the counter electrode is set to the thickness of the liquid crystal layer between the reflection pixel electrode and the counter electrode. It is characterized in that it is twice as long.
[0054]
According to the above invention, the optical path length of the ambient light passing back and forth through the liquid crystal layer corresponding to the reflective pixel electrode region and the liquid crystal layer corresponding to the transmissive pixel electrode region pass The optical path length of the transmitted light in the liquid crystal layer can be matched.
[0055]
Therefore, it is possible to make the changes in the light characteristics of the liquid crystal layer corresponding to the reflective pixel electrode region and the liquid crystal layer corresponding to the transmissive pixel electrode region coincide. Therefore, the light utilization efficiency can be further increased.
[0056]
The liquid crystal display device of the present invention is characterized in that, in the liquid crystal display device described above, the peripheral portion of the transmissive pixel electrode is overlapped by a pair of reflective pixel electrodes through one or more insulating films. It is said.
[0057]
According to the above invention, since the reflective pixel electrode forming a pair is superimposed on the transmissive pixel electrode via the insulating film, the region of the reflective pixel electrode is further expanded, and as a result, the reflective pixel electrode is expanded. The area of the combined region of the pixel electrode for transmission and the pixel electrode for transmission increases.
[0058]
Therefore, the aperture ratio of the entire liquid crystal display device is increased, and the light use efficiency can be increased.
[0059]
In the liquid crystal display device of the present invention, in the liquid crystal display device described above, the reflection auxiliary capacitance element is formed by a reflection auxiliary capacitance line and a conductive film electrically connected to the reflection pixel electrode, and is transmissive. The auxiliary storage capacitor element is formed by a transmission auxiliary capacitance line and a transmission pixel electrode, and the reflection auxiliary capacitance line and the transmission auxiliary capacitance line form a pair of the reflection pixel electrode and the transmission pixel electrode. In FIG. 4, the same wiring is used, and the storage capacitor wiring is not overlapped with a region of the transmission pixel electrode on which the reflection pixel electrode is not overlapped.
[0060]
According to the above invention, the auxiliary capacitance wiring used for the auxiliary capacitance of the reflective pixel electrode and the auxiliary capacitance wiring used for the auxiliary capacitance of the transmissive pixel electrode become a common auxiliary capacitance wiring. Further, the common auxiliary capacitance line does not overlap with a region of a transmissive pixel electrode used for liquid crystal display.
[0061]
Therefore, the actual area used for the liquid crystal display of the transmissive pixel electrode can be further increased by the area of the auxiliary capacitance wiring. Therefore, the aperture ratio of the entire liquid crystal display device can be further increased, and the light utilization efficiency can be further increased.
[0062]
In the liquid crystal display device of the present invention, in the liquid crystal display device described above, the first gate wiring and the second gate wiring are the same wiring in the reflective pixel electrode and the transmissive pixel electrode that form a pair. It is characterized by.
[0063]
According to the above invention, the first gate wiring and the second gate wiring are the same wiring in the reflective pixel electrode and the transmissive pixel electrode that form a pair. It is possible to reduce the number of gate wirings for the pixel electrode including the pixel electrode from two to one.
[0064]
Therefore, the pixels can be miniaturized, and a liquid crystal display device with high resolution can be obtained, and at the same time, the yield during production of the liquid crystal display device can be greatly reduced.
[0065]
DETAILED DESCRIPTION OF THE INVENTION
[Embodiment 1]
An embodiment of the present invention will be described with reference to FIGS. 1 to 6 as follows.
[0066]
As shown in FIG. 1, the active matrix substrate 1a of the present embodiment has pixel electrodes 2 arranged in a matrix. A gate line 3 for supplying a scanning signal and a source line 4 for supplying a display signal are provided so as to pass through the periphery of the pixel electrode 2 and to be orthogonal to each other.
[0067]
The gate wiring 3 and the source wiring 4 are formed of a metal film, and a part of the gate wiring 3 and the source wiring 4 overlap with the outer peripheral portion of the pixel electrode 2 via the gate insulating film 11 (see FIGS. 2 and 3).
[0068]
A thin film transistor (TFT) 5 as a switching element for supplying a display signal to the pixel electrode 2 is provided in the vicinity of the intersection between the gate line 3 and the source line 4.
[0069]
A gate wiring 3 is connected to the gate electrode 6 of the thin film transistor (TFT) 5, and the thin film transistor (TFT) 5 is driven and controlled by a signal input to the gate electrode 6. A source wiring 3 is connected to the source electrode 7 of the thin film transistor (TFT) 5, and a data signal is input to the source electrode 7.
[0070]
In addition, as a feature of the active matrix substrate 1a of the present embodiment, the pixel electrode 2 includes a reflective pixel electrode 2a made of a metal film and a transmissive pixel electrode 2b made of a transparent conductive film. Further, the gate wiring 3, the thin film transistor (TFT) 5, the gate electrode 6, the source electrode 7, the drain electrode 8, and the auxiliary capacitance wiring 12 are individually connected to the reflection pixel electrode 2a and the transmission pixel electrode 2b. Each is provided individually for control.
[0071]
That is, as the reflective pixel electrode 2a, the reflective gate wiring 3a (first gate wiring), the reflective thin film transistor (TFT) 5a (first switching element), the reflective gate electrode 6a, and the reflective source electrode 7a. Further, a reflection drain electrode 8a and a reflection auxiliary capacitance line 12a are provided. For the transmission pixel electrode 2b, a transmission gate wiring 3b (second gate wiring), a transmission thin film transistor (TFT) 5b (second switching element), a transmission gate electrode 6b, and a transmission source electrode 7b. A transmission drain electrode 8b and a transmission auxiliary capacitance line 12b are provided.
[0072]
Next, a cross-sectional structure of a liquid crystal display device using the active matrix substrate 1a will be described.
[0073]
As shown in FIG. 2 (a cross-sectional view taken along line AA in FIG. 1), the active matrix substrate 1a is provided with a reflective gate electrode 6a on the transparent insulating substrate 15, and the reflective gate. The electrode 6 a is covered with the gate insulating film 11. A semiconductor layer 16 and a doped semiconductor layer 17 are stacked in this order on the gate insulating film 11. Further, a reflective source electrode 7a and a reflective drain electrode 8a formed of two layers of a transparent conductive film made of ITO (Indium Tin Oxide) and a metal film are formed so as to cover the doped semiconductor layer 17. Has been.
[0074]
The reflective source electrode 7a is connected to the source wiring 4 made of the transparent conductive film and the metal film, and the reflective drain electrode 8a is connected to the transparent conductive film and the metal film. The electrode 10 is connected. Note that the connection electrode 10 has a two-layer structure at a position in contact with the reflection pixel electrode 2a through the contact hole 9, but at other positions, the connection electrode 10 is formed of one layer of the transparent conductive film. Is formed.
[0075]
Further, the reflection pixel electrode 2a is formed on the electrodes 7a and 8a with an interlayer insulating film 18 interposed therebetween. A liquid crystal layer 29 is formed between the reflective pixel electrode 2 a and the counter electrode 14 formed on the counter substrate 13.
[0076]
Further, as shown in FIG. 3 (a cross-sectional view taken along line BB in FIG. 1), a reflection auxiliary capacitance wiring 12a is provided on the transparent insulating substrate 15. On the gate insulating film 11, a transmission pixel electrode 2b formed of the transparent conductive film is provided. Here, the connection electrode 10 and the transmissive pixel electrode 2b are respectively formed on the reflection auxiliary capacitance lines 12a and 12b via the gate insulating film 11.
[0077]
Furthermore, as shown in FIG. 4 (cross-sectional view taken along the line CC in FIG. 1), a transparent gate electrode 6b is provided on the transparent insulating substrate 15, and the transparent gate electrode 6b is a gate. It is covered with an insulating film 11. A semiconductor layer 16 and a doped semiconductor layer 17 are stacked in this order on the gate insulating film 11. Further, a transmissive source electrode 7b and a transmissive drain electrode 8b formed by two layers of the transparent conductive film and the metal film are formed so as to cover the doped semiconductor layer 17.
[0078]
The transmission source electrode 7b is connected to the source wiring 4 made of the transparent conductive film and the metal film, and the transmission drain electrode 8b is connected to the transmission pixel electrode 2b.
[0079]
With the above configuration, the connection electrode 10 electrically connected to the drain electrode 8a forms a reflection auxiliary capacitance element by the auxiliary capacitance wiring 12a and the gate insulating film 11 interposed therebetween. The transmission pixel electrode 2b forms a transmission auxiliary capacitance element by the auxiliary capacitance line 12b and the gate insulating film 11 interposed therebetween.
[0080]
Further, since the transmission pixel electrode 2b is formed on the gate insulating film 11 as described above, it is directly connected to the transmission drain electrode 8b, and the reflection pixel electrode 2a and the reflection drain electrode 8a are connected to each other. Components such as the contact hole 9 to be connected are not necessary.
[0081]
The auxiliary capacitance lines 12a and 12b are formed of a metal film, and are connected to the counter electrode 14 formed on the counter substrate 13 by a wiring (not shown). Moreover, the reason why the source wiring 4 has a two-layer structure of the transparent conductive film and the metal film is to provide redundancy for defects such as disconnection.
[0082]
The active matrix substrate 1a is configured as described above. Next, a method for manufacturing the active matrix substrate 1a will be described.
[0083]
First, a reflective gate electrode 6a and a transmissive gate electrode 6b, a reflective gate line 3a and a transmissive gate line 3b, a reflective auxiliary capacitance line 12a, and a transmissive auxiliary capacitance line are formed on a transparent insulating substrate 15 such as glass. 12b is formed by sputtering or the like, and then patterned through a photolithography process.
[0084]
Next, the gate insulating film 11, the semiconductor layer 16, and the doped semiconductor layer 17 are formed using a plasma CVD method. Subsequently, a transparent electrode film made of ITO (Indium Tin Oxide) is formed by a sputtering method, and the connection electrode 10 and the transmission pixel electrode 2b are formed through a photolithography process. Further, after forming a metal film by a sputtering method, patterning is performed to form the source wiring 4, the reflection source electrode 7a and the transmission source electrode 7b, the reflection drain electrode 8a, and the transmission drain electrode 8b. .
[0085]
Thereafter, a photosensitive acrylic resin is formed as an interlayer insulating film 18 to a thickness of 3 μm by spin coating. Further, the acrylic resin is subjected to pattern exposure and developed with an alkaline solution. As a result, only the exposed portion is etched with an alkaline solution to form a contact hole 9 penetrating the interlayer insulating film 18. The contact hole 9 is formed to have a good taper shape.
[0086]
Thus, by using a photosensitive acrylic resin as the interlayer insulating film 18, a thin film can be formed by a spin coating method. Therefore, a thin film having a thickness of several μm can be easily formed. Further, the patterning of the interlayer insulating film 18 is advantageous in terms of productivity, such as eliminating the need for a photoresist coating process.
[0087]
The acrylic resin in this embodiment is colored and can be made transparent by exposing the entire surface after patterning. The acrylic resin can be made transparent by chemical treatment.
[0088]
Next, the reflective pixel electrode 2a, the reflective gate line 3a and the transmissive gate line 3b, the source line 4, the reflective thin film transistor (TFT) 5a and the transmissive thin film transistor (TFT) 5b are formed on the interlayer insulating film 18. And to be overlapped with the reflection auxiliary capacitance line 12a. In the present embodiment, when the reflective pixel electrode 2a is formed, aluminum (Al) is formed by a sputtering method and then patterned by a photolithography process. However, the material of the reflection pixel electrode 2a is not limited to aluminum (Al), and other metal materials such as silver (Ag) or AlSi (Si content of about 1%) are used. A base alloy may be used as long as the film has high reflectivity and conductivity.
[0089]
As described above, the active matrix substrate 1a in the present embodiment can be manufactured.
[0090]
Furthermore, a liquid crystal cell is manufactured using a conventionally known method such as bonding with an alignment coating film and the counter substrate 13, injection of a liquid crystal material, and bonding of a polarizing plate, and a backlight is installed on the back surface. Thus, a liquid crystal display device using the active matrix substrate 1a is completed.
[0091]
Further, since the active matrix substrate 1a is provided with the reflective pixel electrode 2a on the interlayer insulating film 18, the surface of the interlayer insulating film 18 can be formed on the surface by forming irregularities by a photolithography process or the like. A reflective pixel electrode 2a having irregularities can be obtained. Therefore, the unevenness of the surface of the reflection pixel electrode 2a makes it possible to use ambient light at various incident angles, and a brighter liquid crystal display device can be realized.
[0092]
In the liquid crystal device, the thickness of the liquid crystal layer 29 between the transmission pixel electrode 2b and the counter electrode 14 is set to the thickness of the liquid crystal layer between the reflection pixel electrode 2a and the counter electrode 14. It is desirable to make it thicker than 29. Thereby, the optical path length of the light reflected by the reflection pixel electrode 2a in the liquid crystal layer 29 and the optical path length of the light passing through the transmission pixel electrode 2b in the liquid crystal layer 29 can be made closer to each other. Accordingly, it is possible to make uniform the change in the light characteristics in both the liquid crystal layers 29, and to increase the light use efficiency.
[0093]
Further, the thickness of the liquid crystal layer 29 between the transmission pixel electrode 2b and the counter electrode 14 is set to be equal to the thickness of the liquid crystal layer 29 between the reflection pixel electrode 2a and the counter electrode 14. More preferably, it is doubled. Thereby, the optical path length of the light reflected by the reflection pixel electrode 2a in the liquid crystal layer 29 and the optical path length of the light passing through the transmission pixel electrode 2b in the liquid crystal layer 29 can be made the same. Therefore, it is possible to make the change in the characteristics of light in both the liquid crystal layers 29 coincide, and it is possible to further increase the light use efficiency.
[0094]
As described above, the active matrix substrate 1a in the present embodiment has a configuration in which the reflective pixel electrode 2a that performs reflective display and the transmissive pixel electrode 2b that performs transmissive display are independent. Control of the pixel electrode 2a and the transmissive pixel electrode 2b can be performed using individual parameters. In the present embodiment, as described above, the reflection pixel electrode 2a and the transmission pixel electrode 2b are independently controlled as separate pixels. However, the display of an image is only used as a set.
[0095]
Incidentally, in the conventional liquid crystal display device, as shown in FIG. 13, a reflective region (reflective pixel electrode) 26 and a transmissive region (transparent pixel electrode) 28 are formed in the same pixel, and the reflective region and transmissive region are transmitted. Since the thickness of the liquid crystal with the region is changed to be different, the capacitance Clc of the liquid crystal layer has different values. In the liquid crystal display device, the parasitic capacitance Cgd between the gate electrode and the drain electrode, the capacitance (auxiliary capacitance) Ccs of the auxiliary capacitance element, and the gate potential difference ΔVg are the same for each of the regions 26 and 28 due to the configuration of the liquid crystal device. Are the same. Therefore, each optimum counter voltage is different, and the difference between the voltage of the counter electrode (not shown) and the optimum counter voltage of the reflection region 26 and / or the voltage of the counter electrode and the optimum counter voltage of the transmission region 28 is different. The deviation is a cause of lowering the display quality.
[0096]
On the other hand, the liquid crystal display device using the active matrix substrate 1a according to the present embodiment controls the reflection pixel electrode 2a and the transmission pixel electrode 2b using individual parameters, as will be described later. By matching the optimal counter voltage of the reflective pixel electrode 2a with the optimal counter voltage of the transmissive pixel electrode 2b, and setting the voltage of the counter electrode 14 to the voltage value of the optimal counter voltage, It is possible to eliminate the deviation between the voltage and the optimum counter voltage of the reflection pixel electrode 2a and the difference between the voltage of the counter electrode 14 and the optimum counter voltage of the transmission pixel electrode 2b.
[0097]
Therefore, a highly reliable liquid crystal display device capable of high-quality display with high light use efficiency can be obtained. In addition, the flicker phenomenon can be suppressed even when driving at a low frequency to reduce power consumption.
[0098]
A control method using parameters for matching the optimum counter voltage of the reflection pixel electrode 2a and the optimum counter voltage of the transmission pixel electrode 2b will be described below.
[0099]
As described above, the voltage applied to each of the pixel electrodes 2a and 2b does not match the source voltage, and shifts from the source voltage at the moment when the gate is closed.
[0100]
On the other hand, the parameters for controlling the potential shift include, for example, the parasitic capacitance Cgd between the gate electrode and the drain electrode, the capacitance Clc of the liquid crystal layer 29, and the auxiliary capacitance due to the wiring pattern, structure, and material. There are various capacitance design parameters such as element capacitance (hereinafter referred to as auxiliary capacitance) Ccs, and parameters based on input signals such as the gate potential difference ΔVg.
[0101]
Therefore, the optimum counter voltage of the reflection pixel electrode 2a and the optimum counter voltage of the transmission pixel electrode 2b are controlled by individually controlling the various capacitance design parameters for the reflection pixel electrode 2a and the transmission pixel electrode 2b. A first method for matching these will be described. Next, by individually controlling the parameters of the input signal for the reflective pixel electrode 2a and the transmissive pixel electrode 2b, the optimal counter voltage of the reflective pixel electrode 2a and the optimal counter voltage of the transmissive pixel electrode 2b A second method for matching these will be described. Furthermore, the optimum counter voltage and the transmission pixel of the reflection pixel electrode 2a are controlled by individually controlling the above-described various capacitance design parameters and parameters based on the input signals for the reflection pixel electrode 2a and the transmission pixel electrode 2b. A third method for matching the optimum counter voltage of the electrode 2b will be described. Finally, a fourth method for matching the optimum counter voltage of the reflective pixel electrode 2a and the optimum counter voltage of the transmissive pixel electrode 2b by controlling the source signal will be described.
[0102]
First, a first method for individually controlling various capacity design parameters will be described. In this method, gate signals having the same amplitude are input to the reflection pixel electrode 2a and the transmission pixel electrode 2b.
[0103]
Here, the voltage shift amount from the source signal voltage of the reflection pixel electrode potential (hereinafter referred to as the voltage shift amount of the reflection pixel electrode 2a) is ΔVd (r), and the voltage shift from the source signal voltage of the transmission pixel electrode potential. When the amount (hereinafter referred to as the voltage shift amount of the transmissive pixel electrode 2b) is ΔVd (t), ΔVd (r) and ΔVd (t) are respectively expressed by the following equation (2) according to the above equation (1). And (3).
[0104]
ΔVd (r) = ΔVg (r) × Cgd (r) / (Cgd (r) + Clc (r) + Ccs (r)) (2)
ΔVd (t) = ΔVg (t) × Cgd (t) / (Cgd (t) + Clc (t) + Ccs (t)) (3)
Note that the gate potential difference of the reflection pixel electrode 2a is ΔVg (r), the parasitic capacitance between the reflection gate electrode 6a and the reflection drain electrode 8a is Cgd (r), the reflection pixel electrode 2a and the counter electrode 14 are The capacity of the liquid crystal layer 29 between the two is defined as Clc (r), and the auxiliary capacity connected to the reflective pixel electrode is defined as Ccs (r). Further, the gate potential difference of the transmission pixel electrode 2b is ΔVg (t), the parasitic capacitance between the transmission gate electrode 6b and the transmission drain electrode 8b is Cgd (t), the transmission pixel electrode 2b and the counter electrode 14 The capacity of the liquid crystal layer 29 between the two is defined as Clc (t), and the auxiliary capacity connected to the transmission pixel electrode is defined as Ccs (t). Here, the gate potential differences ΔVg (r) · ΔVg (t) are respectively the high level voltage Vgh (r) · Vgh (t) of each gate signal and the low level voltage Vgl (r) · Vgl (t) of each gate signal. ).
[0105]
On the other hand, since the gate signal of the reflection pixel electrode 2a and the gate signal of the transmission pixel electrode 2b have the same amplitude, the gate potential difference ΔVg (r) of the reflection pixel electrode 2a and the gate potential difference of the transmission pixel electrode 2b. ΔVg (t) is the same value.
[0106]
Therefore, in order to make the voltage shift amount ΔVd (r) of the reflective pixel electrode 2a and the voltage shift amount ΔVd (t) of the transmissive pixel electrode 2b the same, the liquid crystal display satisfies the following formula (4). What is necessary is just to design an apparatus.
[0107]
Cgd (r) / (Cgd (r) + Clc (r) + Ccs (r)) = Cgd (t) / (Cgd (t) + Clc (t) + Ccs (t)) (4)
In other words, the parasitic capacitances Cgd (r) · Cgd (t), the capacitances Clc (r) · Clc (t) of the liquid crystal layers 29, and the auxiliary capacitances Ccs ( By selecting r) · Ccs (t), the voltage shift amount ΔVd (r) of the reflective pixel electrode 2a and the voltage shift amount ΔVd (t) of the transmissive pixel electrode 2b can be made the same. .
[0108]
As described above, the optimum counter voltage of the reflection pixel electrode 2a and the optimum counter voltage of the transmission pixel electrode 2b can be matched.
[0109]
Alternatively, the same gate signal may be input with the reflective gate line 3a and the transmissive gate line 3b as a set. In this case, it is possible to avoid the frequency of the gate signal being twice the frequency of the gate signal having the conventional structure.
[0110]
That is, in the active matrix substrate 1a of the present embodiment, as described above, the pixel electrode 2 is composed of the reflective pixel electrode 2a made of a metal film and the transmissive pixel electrode 2b made of a transparent conductive film, and each is individually provided. Gate wirings 3a and 3b are provided. Therefore, in the active matrix substrate 1a, the phase of the gate signal from the gate wiring connected to the reflective pixel electrode and the gate signal from the gate wiring connected to the transmissive pixel electrode are compared with the active matrix substrate having the conventional structure. Therefore, it is necessary to input a gate signal having a double frequency. However, as described above, by inputting the same gate signal, that is, the gate signal having the same amplitude and the same phase, with the reflection gate wiring 3a and the transmission gate wiring 3b as a set, a gate signal having a double frequency is input. Is not required to be input, and display can be performed by inputting a gate signal having the same frequency as that of an active matrix substrate used in a conventional liquid crystal display device.
[0111]
Next, a second method for individually controlling parameters based on input signals will be described.
[0112]
In the active matrix substrate used in the conventional liquid crystal display device, as described above, since the thickness of the liquid crystal in the reflective region 26 and the transmissive region 28 is different, the capacitance Clc of the liquid crystal layer is different from each other. On the other hand, the parasitic capacitance Cgd between the gate electrode and the drain electrode, the auxiliary capacitance Ccs, and the gate potential difference ΔVg are the same in each of the regions 26 and 28. Therefore, the value of Cgd / (Cgd + Clc + Ccs) is different in each of the regions 26 and 28. Therefore, the voltage shift values ΔVd of the regions 26 and 28 shown in the above equation (1) are also different values.
[0113]
Therefore, in the present embodiment, even when the value of Cgd / (Cgd + Clc + Ccs) differs between the reflective pixel electrode 2a and the transmissive pixel electrode 2b, the voltage shift amount ΔVd (r) of the reflective pixel electrode 2a. The gate potential difference ΔVg (r) of the reflective pixel electrode 2a and the gate potential difference ΔVg (t) of the transmissive pixel electrode 2b are individually set so that the voltage shift amount ΔVd (t) of the transmissive pixel electrode 2b is the same. Control.
[0114]
In other words, the voltage shift amount ΔVd (r) of the reflective pixel electrode 2a and the voltage shift amount ΔVd (t) of the transmissive pixel electrode 2b are expressed by the above equations (2) and (3), respectively. The liquid crystal display device may be designed so as to satisfy the following formula (5).
[0115]
ΔVg (r) × Cgd (r) / (Cgd (r) + Clc (r) + Ccs (r)) = ΔVg (t) × Cgd (t) / (Cgd (t) + Clc (t) + Ccs (t)) (5)
Thus, the value of Cgd (r) / (Cgd (r) + Clc (r) + Ccs (r)) of the reflective pixel electrode 2a and Cgd (t) / (Cgd (t) + Clc of the transmissive pixel electrode 2b are obtained. Even when the values of (t) + Ccs (t)) are different from each other, the gate potential difference ΔVg (r) of the reflection pixel electrode 2a and the gate potential difference ΔVg (t) of the transmission pixel electrode 2b are individually controlled. Thus, the voltage shift amount ΔVd (r) of the reflection pixel electrode 2a and the voltage shift amount ΔVd (t) of the transmission pixel electrode 2b can be made the same.
[0116]
Hereinafter, the control using the second method will be specifically described with reference to FIGS. 5 (a) and 5 (b).
[0117]
Conventionally, as shown in FIGS. 14A to 14E, a gate signal in which the gate potential difference ΔVg (r) of the reflection pixel electrode 26 and the gate potential difference ΔVg (t) of the transmission pixel electrode 28 are the same. Even if the shift amount ΔVd (r) is input, the shift amount ΔVd (r) of the reflection pixel electrode 26 and the shift amount ΔVd (t) of the transmission pixel electrode 28 are different. Therefore, in this embodiment, for example, as shown in FIG. 5A, the high level voltage Vgh (t) of the gate signal in the transmissive pixel electrode 2b is controlled, for example, Vgh (t)> Vgh ( t) is corrected to Vgh (t) ′.
[0118]
On the other hand, the drain voltage applied to the transmissive pixel electrode 2b changes in proportion to the gate potential difference ΔVg (ΔVg = Vgh × Vgl) according to the above equation (1). Therefore, by correcting the high level voltage Vgh (t) of the gate signal to Vgh (t) ′, the shift amount of the drain voltage applied to the transmissive pixel electrode 2b is also ΔVd as shown in FIG. 5B. It changes from (t) to ΔVd (t) ′.
[0119]
Accordingly, the voltage Vgh when the gate signal is input so that the corrected voltage shift amount ΔVd (t) ′ of the transmission pixel electrode 2b becomes equal to the voltage shift amount ΔVd (r) of the reflection pixel electrode 2a. The value of (t) ′ may be determined. That is, as shown in FIG. 5A, the value of Vgh (t) is set to a smaller value Vgh (t) ′, and the voltage shift amount is reduced by the difference ΔVs between ΔVd (t) and ΔVd (r). For example, the voltage shift amount ΔVd (r) of the reflection pixel electrode 2a is equal to the corrected voltage shift amount ΔVd (t) ′ of the transmission pixel electrode 2b. However, in FIG. 14D and FIG. 14E, ΔVd (t)> ΔVd (r) is set for convenience.
[0120]
As described above, the optimum counter voltage of the reflection pixel electrode 2a and the optimum counter voltage of the transmission pixel electrode 2b can be matched.
[0121]
Next, a third method for individually controlling various capacity design parameters and parameters based on input signals will be described.
[0122]
The voltage shift amount ΔVd (r) of the reflection pixel electrode 2a and the voltage shift amount ΔVd (t) of the transmission pixel electrode 2b are expressed by the above equations (2) and (3), respectively. Therefore, whether or not the gate signal inputted to the reflection pixel electrode 2a and the transmission pixel electrode 2b is the same, or Cgd (r) / (Cgd (r) + Clc (r) of the reflection pixel electrode 2a. ) + Ccs (r)) and the value of Cgd (t) / (Cgd (t) + Clc (t) + Ccs (t)) of the transmission pixel electrode 2b are different from each other. The gate potential difference ΔVg (r) of the reflection pixel electrode 2a, the parasitic capacitance Cgd (r) between the reflection gate electrode 6a and the reflection drain electrode 8a, and the reflection pixel electrode 2a so as to satisfy Expression (5). And the counter electrode 14, the capacitance Clc (r) of the liquid crystal layer 29, the auxiliary capacitance Ccs (r) connected to the reflection pixel electrode, the gate potential difference ΔVg (t) of the transmission pixel electrode 2 b, the transmission gate Electrode 6b and The parasitic capacitance Cgd (t) between the transmission drain electrode 8b, the capacitance Clc (t) of the liquid crystal layer 29 between the transmission pixel electrode 2b and the counter electrode 14, and the auxiliary connected to the transmission pixel electrode A capacitor Ccs (t) may be selected.
[0123]
This also makes it possible to make the voltage shift amount ΔVd (r) of the reflective pixel electrode 2a the same as the voltage shift amount ΔVd (t) of the transmissive pixel electrode 2b.
[0124]
As described above, the optimum counter voltage of the reflection pixel electrode 2a and the optimum counter voltage of the transmission pixel electrode 2b can be matched.
[0125]
Next, a fourth method for controlling the source signal will be described.
[0126]
As described above, the voltage shift amount ΔVd (r) of the reflective pixel electrode 2a and the voltage shift amount ΔVd (t) of the transmissive pixel electrode 2b are given by the above equations (2) and (3), respectively. . Therefore, the difference ΔVs between ΔVd (t) and ΔVd (r) is expressed by the following equation (6).
[0127]
ΔVs = ΔVg (r) × Cgd (r) / (Cgd (r) + Clc (r) + Ccs (r)) − ΔVg (t) × Cgd (t) / (Cgd (t) + Clc (t) + Ccs (t) (6)
Therefore, in the present embodiment, for example, as shown in FIG. 6A, the difference ΔVs between ΔVd (t) and ΔVd (r) is previously applied to only the source signal applied to the transmission pixel electrode 2b. Add to. As a result, as shown in FIG. 6B, the voltage shift amount is reduced by the difference ΔVs between ΔVd (t) and ΔVd (r). Accordingly, as in the second control method, the voltage shift amount ΔVd (r) of the reflection pixel electrode 2a is equal to the corrected voltage shift amount ΔVd (t) ′ of the transmission pixel electrode 2b.
[0128]
As described above, the optimum counter voltage of the reflection pixel electrode 2a and the optimum counter voltage of the transmission pixel electrode 2b can be matched.
[0129]
Therefore, the liquid crystal display layer device including the active matrix substrate 1a is used to perform control using parameters for matching the optimum counter voltage of the reflection pixel electrode 2a and the optimum counter voltage of the transmission pixel electrode 2b. As a result, a highly reliable liquid crystal display device with high light utilization efficiency and high-quality display can be obtained. In addition, the flicker phenomenon can be suppressed even when driving at a low frequency to reduce power consumption.
[0130]
In addition, this invention is not limited to said embodiment, A various change is possible within the scope of the present invention.
[0131]
[Embodiment 2]
The following will describe another embodiment of the present invention with reference to FIGS. For convenience of explanation, members having the same functions as those shown in the drawings of the first embodiment are given the same reference numerals and explanation thereof is omitted.
[0132]
As shown in FIG. 7, the active matrix substrate 1b of the present embodiment has a larger proportion of the reflective pixel electrode 2a in one pixel. The reflective pixel electrode 2a has an opening P1 having a shape along the outer periphery of the transmissive pixel electrode 2b, and the display by the transmissive pixel electrode 2b is visually recognized only in the opening P1. be able to.
[0133]
That is, as shown in FIG. 8, the reflective pixel electrode 2a forming a pair is superimposed on the peripheral portion of the transmissive pixel electrode 2b with the interlayer insulating film 18 interposed therebetween.
[0134]
More specifically, the reflective pixel electrode 2a includes a transmissive gate electrode 3b, a transmissive gate electrode 6b between the peripheral part of the transmissive pixel electrode 2b and the adjacent source line 4, and a transmissive gate electrode 6b. Overlying the source electrode 7b and a part of the transmissive drain electrode 8b with at least one interlayer insulating film 18 therebetween.
[0135]
As described above, the active matrix substrate 1b of the present embodiment can have a higher aperture ratio than the active matrix substrate 1a of the first embodiment. Therefore, it is possible to prevent a decrease in contrast without providing a light blocking black matrix on the counter substrate 13 side, and it is possible to improve the light utilization efficiency.
[0136]
On the other hand, as shown in the first embodiment, in order to prevent flicker and display with high quality, the optimum counter voltage of the reflective pixel electrode 2a and the optimum counter voltage of the transmissive pixel electrode 2b are matched. In addition, it is desirable that the voltage of the counter electrode 14 be the optimum counter voltage.
[0137]
Therefore, also in this embodiment, the control method using parameters shown in the first embodiment is used. In other words, the reflective pixel electrode 2a and the transmissive pixel electrode 2b are controlled using individual parameters so that the optimum counter voltage of the reflective pixel electrode 2a and the optimum counter voltage of the transmissive pixel electrode 2b are matched. In addition, by setting the voltage of the counter electrode 14 to the voltage value of the optimum counter voltage, the difference between the voltage of the counter electrode 14 and the optimum counter voltage of the reflective pixel electrode 2a, and the voltage and transmission of the counter electrode 14 are transmitted. The deviation from the optimum counter voltage of the pixel electrode 2b is eliminated.
[0138]
Since the control method using the above parameters can be realized by using any one of the four methods shown in the first embodiment, description thereof is omitted.
[0139]
Therefore, by using the active matrix substrate 1b of the present embodiment, it is possible to obtain a highly reliable liquid crystal display device with high light use efficiency and capable of high-quality display. In addition, the flicker phenomenon can be suppressed even when driving at a low frequency to reduce power consumption.
[0140]
In addition, this invention is not limited to said embodiment, A various change is possible within the scope of the present invention.
[0141]
In the above embodiment, the reflection pixel electrode 2a includes the transmission gate electrode 3b between the peripheral part of the transmission pixel electrode 2b and the adjacent source line 4, and the transmission gate electrode 6b. The transparent source electrode 7b and a part of the transparent drain electrode 8b are overlapped with at least one interlayer insulating film 18 interposed therebetween. However, the region overlapped by the pair of reflective pixel electrodes 2a is not particularly limited as described above, and may be a region that can provide a sufficient aperture ratio.
[0142]
[Embodiment 3]
The following will describe another embodiment of the present invention with reference to FIGS. For convenience of explanation, members having the same functions as those shown in the drawings of the first embodiment are given the same reference numerals and explanation thereof is omitted.
[0143]
As shown in FIG. 9, the active matrix substrate 1c of the present embodiment is obtained by increasing the ratio of the reflective pixel electrode 2a to one pixel, as in the second embodiment. The reflective pixel electrode 2a has an opening P2 as in the second embodiment, and the display by the transmissive pixel electrode 2b can be visually recognized only within the opening P2.
[0144]
That is, as shown in FIG. 10, the reflective pixel electrode 2a forming a pair is superimposed on the peripheral portion of the transmissive pixel electrode 2b with the interlayer insulating film 18 interposed therebetween.
[0145]
More specifically, the reflective pixel electrode 2a includes a transmissive gate electrode 3b, a transmissive gate electrode 6b between the peripheral part of the transmissive pixel electrode 2b and the adjacent source line 4, and a transmissive gate electrode 6b. Overlying the source electrode 7b and the transmissive drain electrode 8b with at least one interlayer insulating film 18 therebetween.
[0146]
Further, the auxiliary capacitance wiring 20 connected to the pair of the reflection pixel electrode 2a and the transmission pixel electrode 2b is shared. Further, the common auxiliary capacitance line 20 is disposed at a position overlapping the reflective pixel electrode 2a.
[0147]
Further, the transmission gate electrode 3 b is disposed between the reflection gate electrode 3 a and the auxiliary capacitance line 20.
[0148]
That is, as shown in FIGS. 10 and 11, the active matrix substrate 1c of the present embodiment has a portion of the transmissive pixel electrode 2b excluding a range where the display by the transmissive pixel electrode 2b can be visually recognized. A structure that is disposed between the reflective pixel electrode 2a and the transparent insulating substrate 15 and in which the common auxiliary capacitance wiring 20 is disposed between the transmissive pixel electrode 2b and the transparent insulating substrate 15. It has become.
[0149]
The transmissive pixel electrode 2b forms a transmissive auxiliary capacitance element by the common auxiliary capacitance line 20 and the gate insulating film 11 interposed therebetween.
[0150]
By adopting the structure as described above, the region of the transmissive pixel electrode 2b that can be viewed from the counter substrate 13 side and the auxiliary capacitance wiring 20 do not overlap, so that the region of the transmissive pixel electrode 2b that can be viewed from the counter substrate 13 side. The area can be increased.
[0151]
Therefore, in the active matrix substrate 1c, the portion of the transmissive pixel electrode 2b excluding the range where the display by the transmissive pixel electrode 2b can be visually recognized is between the reflective pixel electrode 2a and the transparent insulating substrate 15. By being arranged, in addition to the increase in the aperture ratio, the aperture ratio can be further increased depending on the arrangement position of the auxiliary capacitance wiring 20.
[0152]
Therefore, in the active matrix substrate 1c, the aperture ratio can be further increased as compared with the second embodiment, and the contrast is prevented from being lowered without providing a black matrix for shading on the counter substrate 13 side. It is possible to increase the light utilization efficiency.
[0153]
On the other hand, in the active matrix substrate 1c, as shown in FIG. 11, the reflection auxiliary capacitance element of the reflective pixel electrode 2a gates the auxiliary capacitance electrode 19 without passing through the connection electrode 10 shown in the first embodiment. It is formed by being superimposed on a common auxiliary capacitance line 20 through the insulating film 11. Further, when the auxiliary capacitance is formed using the connection electrode 10 as in the conventional case, the connection electrode 10 overlaps with the transmission gate wiring 3b and the gate insulating film 11 to generate a considerably large parasitic capacitance. Become. Therefore, in the active matrix substrate 1c, the auxiliary capacitance electrode 19 is connected to the reflection pixel electrode 2a through the contact hole 9, and the interlayer insulation between the reflection pixel electrode 2a and the transmission gate wiring 3b is performed. Employing an acrylic resin having a low dielectric constant and a large film thickness for the film 18 prevents the parasitic capacitance from increasing.
[0154]
On the other hand, as shown in the first embodiment, in order to prevent flicker and display with high quality, the optimum counter voltage of the reflective pixel electrode 2a and the optimum counter voltage of the transmissive pixel electrode 2b are matched. And it is desirable to set the voltage of the counter electrode 14 to the voltage value of the optimum counter voltage.
[0155]
Therefore, also in this embodiment, the control method using parameters shown in the first embodiment is used. In other words, the reflective pixel electrode 2a and the transmissive pixel electrode 2b are controlled using individual parameters so that the optimum counter voltage of the reflective pixel electrode 2a and the optimum counter voltage of the transmissive pixel electrode 2b are matched. In addition, by setting the voltage of the counter electrode 14 to the voltage value of the optimum counter voltage, the difference between the voltage of the counter electrode 14 and the optimum counter voltage of the reflective pixel electrode 2a, and the voltage and transmission of the counter electrode 14 are transmitted. The deviation from the optimum counter voltage of the pixel electrode 2b is eliminated.
[0156]
Since the control method using the above parameters can be realized by using any one of the four methods shown in the first embodiment, description thereof is omitted.
[0157]
Therefore, by using the active matrix substrate 1c of the present embodiment, it is possible to obtain a highly reliable liquid crystal display device with high light use efficiency and capable of high-quality display. In addition, the flicker phenomenon can be suppressed even when driving at a low frequency to reduce power consumption.
[0158]
In addition, this invention is not limited to said embodiment, A various change is possible within the scope of the present invention.
[0159]
For example, the planar shape of the reflective pixel electrode 2a forming a set may be various shapes within the range in which the auxiliary capacitance wiring 20 is arranged at the position where it is superimposed on the reflective pixel electrode 2a as described above.
[0160]
[Embodiment 4]
The following will describe another embodiment of the present invention with reference to FIG. For convenience of explanation, members having the same functions as those shown in the drawings of Embodiment 1 or Embodiment 3 are given the same reference numerals, and the description thereof is omitted.
[0161]
As shown in FIG. 12, the active matrix substrate 1d according to the present embodiment uses the reflective gate wiring 3a and the transmission gate wiring 3b of the active matrix substrate 1c according to the third embodiment as a common gate wiring 3, and accordingly, The common gate electrode 6 is used for the reflective gate electrode 6a and the transmissive gate electrode 6b of the active matrix substrate 1c.
[0162]
Therefore, the number of gate wirings of the active matrix substrate 1d only needs to be half the number of gate wirings of the active matrix substrate 1c in the third embodiment. As a result, in the present embodiment, in addition to the effects obtained in the third embodiment, it is possible to miniaturize a pixel composed of a set of the reflective pixel electrode 2a and the transmissive pixel electrode 2b. A liquid crystal display device having a high level can be obtained. Furthermore, the yield during production of the active matrix substrate 1d can be reduced, and the production efficiency of the liquid crystal display device including the active matrix substrate 1d can be increased.
[0163]
On the other hand, as shown in the first embodiment, in order to prevent flicker and display with high quality, the optimum counter voltage of the reflective pixel electrode 2a and the optimum counter voltage of the transmissive pixel electrode 2b are matched. And it is desirable to set the voltage of the counter electrode 14 to the voltage value of the optimum counter voltage.
[0164]
Therefore, also in this embodiment, the control method using parameters shown in the first embodiment is used. In other words, the reflective pixel electrode 2a and the transmissive pixel electrode 2b are controlled using individual parameters so that the optimum counter voltage of the reflective pixel electrode 2a and the optimum counter voltage of the transmissive pixel electrode 2b are matched. In addition, by setting the voltage of the counter electrode 14 to the voltage value of the optimum counter voltage, the difference between the voltage of the counter electrode 14 and the optimum counter voltage of the reflective pixel electrode 2a, and the voltage and transmission of the counter electrode 14 are transmitted. The deviation from the optimum counter voltage of the pixel electrode 2b is eliminated.
[0165]
Since the control method using the above parameters can be realized by using any one of the four methods shown in the first embodiment, description thereof is omitted.
[0166]
Therefore, by using the active matrix substrate 1d of the present embodiment, it is possible to obtain a highly reliable liquid crystal display device with high light use efficiency and capable of high-quality display. In addition, the flicker phenomenon can be suppressed even when driving at a low frequency to reduce power consumption.
[0167]
In addition, this invention is not limited to said embodiment, A various change is possible within the scope of the present invention.
[0168]
For example, as described in the third embodiment, the planar shape of the reflective pixel electrode 2a forming a set is a range in which the auxiliary capacitance wiring 20 is arranged at the position where the reflective pixel electrode 2a is superimposed as described above. Inside, it is good also as various shapes.
[0169]
【The invention's effect】
In the liquid crystal display device of the present invention, as described above, the switching element includes a first switching element and a second switching element, and the reflective pixel electrode is connected to the first switching element via the first switching element. The transmission pixel electrode is connected to the second gate wiring via a second switching element, and the auxiliary capacitive element is connected to the reflective pixel electrode. An auxiliary capacitance element for transmission connected to the pixel electrode for transmission, and an amplitude of a gate signal input to the first gate wiring and an amplitude of the gate signal input to the second gate wiring A parasitic capacitance between the gate electrode and the drain electrode of the first switching element, a parasitic capacitance between the gate electrode and the drain electrode of the second switching element, and the reflection pixel electrode And the counter electrode, the liquid crystal layer capacitance between the transmission pixel electrode and the counter electrode, the reflection auxiliary capacitance element capacitance, and the transmission auxiliary capacitance. The capacitance of the element is the same as the amount of voltage shift from the source signal voltage of the pixel electrode potential for reflection and the amount of voltage shift from the source signal voltage of the pixel electrode potential for transmission generated when the switching element is switched. Is set to.
[0170]
Therefore, in the liquid crystal display device of the present invention, it is possible to suppress the occurrence of display defects such as unevenness and haze that occur when the liquid crystal display device is used for a long time. Furthermore, the occurrence of flicker can be suppressed. On the other hand, the use efficiency of light is improved because the reflection pixel electrode and the transmission pixel electrode are used. Therefore, regardless of the state of ambient light, there is an effect that the light use efficiency is high and high-quality display can be made possible.
[0171]
The liquid crystal display device of the present invention is the above liquid crystal display device, wherein the parasitic capacitance between the gate electrode and the drain electrode of the first switching element is Cgd (r), and between the reflective pixel electrode and the counter electrode. The capacitance of the liquid crystal layer is Clc (r), the capacitance of the reflection auxiliary capacitive element is Ccs (r), and the parasitic capacitance between the gate electrode and the drain electrode of the second switching element is Cgd (t). , The capacitance of the liquid crystal layer between the transmission pixel electrode and the counter electrode is Clc (t), and the capacitance of the transmission auxiliary capacitance element is Ccs (t), and the gate is input to the first gate wiring. ΔVg (r) × Cgd (r) / (Cgd (r) where ΔVg (r) is the amplitude of the signal and ΔVg (t) is the amplitude of the gate signal input to the second gate wiring. + Clc (r) + Ccs (r) = Satisfies the ΔVg (t) × Cgd (t) / (Cgd (t) + Clc (t) + Ccs (t)) the relationship.
[0172]
Therefore, the liquid crystal display device has an effect that the optimum counter voltage for reflection and the optimum counter voltage for transmission can be matched.
[0173]
In the liquid crystal display device of the present invention, the same gate signal is input to the first gate wiring and the second gate wiring in the above liquid crystal display device.
[0174]
Therefore, it is not necessary to shift the phase of the gate signal from the gate wiring connected to the reflective pixel electrode and the phase of the gate signal from the gate wiring connected to the transmissive pixel electrode. The frequency of the gate signal can be halved compared to the case where the gate signal is sequentially input. Therefore, there is an effect that high-quality display can be made possible while reducing power consumption.
[0175]
In the liquid crystal display device of the present invention, as described above, the switching element includes a first switching element and a second switching element, and the reflective pixel electrode is connected to the first switching element via the first switching element. The transmission pixel electrode is connected to the second gate wiring via a second switching element, and the auxiliary capacitive element is connected to the reflective pixel electrode. An auxiliary capacitance element for transmission connected to the pixel electrode for transmission, and is generated when the first switching element and the second switching element are switched. After the voltage shift from the source signal voltage of the reflection pixel electrode potential and the voltage shift from the source signal voltage of the transmission pixel electrode potential, on the time axis of the voltage waveform at the reflection pixel electrode and the transmission pixel electrode To match the voltage of the central axis along The source signal voltage applied to the reflective pixel electrode via the first switching element and the second switching element are synchronized with the display timings of the reflective pixel electrode and the transmissive pixel electrode, respectively. The source signal voltage applied to the transmissive pixel electrode is made different.
[0176]
Therefore, in the liquid crystal display device of the present invention, it is possible to suppress the occurrence of display defects such as unevenness and haze that occur when the liquid crystal display device is used for a long time. Furthermore, the occurrence of flicker can be suppressed. On the other hand, the use efficiency of light is improved because the reflection pixel electrode and the transmission pixel electrode are used. Therefore, regardless of the state of ambient light, there is an effect that the light use efficiency is high and high-quality display can be made possible.
[0177]
The liquid crystal display device of the present invention is the above liquid crystal display device, wherein the parasitic capacitance between the gate electrode and the drain electrode of the first switching element is Cgd (r), and between the reflective pixel electrode and the counter electrode. The capacitance of the liquid crystal layer is Clc (r), the capacitance of the reflection auxiliary capacitive element is Ccs (r), and the parasitic capacitance between the gate electrode and the drain electrode of the second switching element is Cgd (t). , The capacitance of the liquid crystal layer between the transmission pixel electrode and the counter electrode is Clc (t), and the capacitance of the transmission auxiliary capacitance element is Ccs (t), and the gate is input to the first gate wiring. When the amplitude of the signal is ΔVg (r) and the amplitude of the gate signal input to the second gate wiring is ΔVg (t), the source signal voltage applied to the reflection pixel electrode, Mark on transparent pixel electrode The difference ΔVs from the applied source signal voltage is ΔVs = ΔVg (r) × Cgd (r) / (Cgd (r) + Clc (r) + Ccs (r)) − ΔVg (t) × Cgd (t) / ( The relationship Cgd (t) + Clc (t) + Ccs (t)) is satisfied.
[0178]
Therefore, the potential after the shift of the reflective pixel electrode and the potential after the shift of the transmissive pixel electrode coincide with each other due to the difference ΔVs between the source signal voltages. Therefore, the liquid crystal display device has an effect that the optimum counter voltage for reflection and the optimum counter voltage for transmission can be matched.
[0179]
In the liquid crystal display device of the present invention, in the above liquid crystal display device, the thickness of the liquid crystal layer between the transmission pixel electrode and the counter electrode is set to the thickness of the liquid crystal layer between the reflection pixel electrode and the counter electrode. It is something larger than that.
[0180]
Therefore, it is possible to make uniform changes in the light characteristics of the liquid crystal layer corresponding to the reflective pixel electrode region and the liquid crystal layer corresponding to the transmissive pixel electrode region. Therefore, there is an effect that the light utilization efficiency can be further increased.
[0181]
In the liquid crystal display device of the present invention, in the above liquid crystal display device, the thickness of the liquid crystal layer between the transmission pixel electrode and the counter electrode is set to the thickness of the liquid crystal layer between the reflection pixel electrode and the counter electrode. This is twice as long.
[0182]
Therefore, it is possible to make the changes in the light characteristics of the liquid crystal layer corresponding to the reflective pixel electrode region and the liquid crystal layer corresponding to the transmissive pixel electrode region coincide. Therefore, there is an effect that it is possible to further increase the light use efficiency.
[0183]
In the liquid crystal display device of the present invention, in the above liquid crystal display device, the periphery of the transmissive pixel electrode is overlapped by a pair of reflective pixel electrodes with one or more insulating films interposed therebetween. .
[0184]
Therefore, the aperture ratio of the entire liquid crystal display device is increased, and the light utilization efficiency can be increased.
[0185]
In the liquid crystal display device of the present invention, in the liquid crystal display device described above, the reflection auxiliary capacitance element is formed by a reflection auxiliary capacitance line and a conductive film electrically connected to the reflection pixel electrode, and is transmissive. The auxiliary storage capacitor element is formed by a transmission auxiliary capacitance line and a transmission pixel electrode, and the reflection auxiliary capacitance line and the transmission auxiliary capacitance line form a pair of the reflection pixel electrode and the transmission pixel electrode. In FIG. 2, the same wiring is used, and the auxiliary capacitance wiring does not overlap with the region of the transmission pixel electrode where the reflection pixel electrode is not superimposed.
[0186]
Therefore, the actual area used for the liquid crystal display of the transmissive pixel electrode can be further increased by the area of the auxiliary capacitance wiring. Therefore, the aperture ratio of the entire liquid crystal display device can be further increased, and the light use efficiency can be further increased.
[0187]
The liquid crystal display device of the present invention is the above liquid crystal display device, wherein the first gate wiring and the second gate wiring are the same wiring in the reflective pixel electrode and the transmissive pixel electrode that form a pair. It is.
[0188]
Therefore, the pixel can be miniaturized, and a high-resolution liquid crystal display device can be obtained, and at the same time, the yield during production of the liquid crystal display device can be greatly reduced.
[Brief description of the drawings]
FIG. 1 is a plan view showing an embodiment of an active matrix substrate in the present invention.
FIG. 2 is a cross-sectional view taken along line AA of the active matrix substrate when the active matrix substrate is used in a liquid crystal display device.
FIG. 3 is a cross-sectional view taken along line BB of the active matrix substrate when the active matrix substrate is used in a liquid crystal display device.
FIG. 4 is a cross-sectional view taken along the line CC of the active matrix substrate when the active matrix substrate is used in a liquid crystal display device.
FIG. 5A is a waveform diagram showing a corrected gate signal input to a gate electrode of a thin film transistor (TFT) connected to a transmission pixel electrode in the active matrix substrate, and FIG. FIG. 6 is a waveform diagram of a signal indicating a corrected drain voltage applied to a transmission pixel electrode in a matrix substrate.
6A is a waveform diagram of a corrected source signal input to a source electrode in the active matrix substrate, and FIG. 6B is a corrected waveform applied to a transmission pixel electrode in the active matrix substrate. It is a wave form diagram of the signal which shows drain voltage.
FIG. 7 is a plan view showing another embodiment of an active matrix substrate in the present invention.
FIG. 8 is a cross-sectional view taken along line DD of the active matrix substrate when the active matrix substrate is used in a liquid crystal display device.
FIG. 9 is a plan view showing still another embodiment of an active matrix substrate according to the present invention.
FIG. 10 is a cross-sectional view taken along line EE of the active matrix substrate when the active matrix substrate is used in a liquid crystal display device.
FIG. 11 is a cross-sectional view of the active matrix substrate taken along line FF when the active matrix substrate is used in a liquid crystal display device.
FIG. 12 is a plan view showing still another embodiment of an active matrix substrate according to the present invention.
FIG. 13 is a plan view showing a conventional active matrix substrate.
14A is a waveform diagram showing a gate signal inputted to a gate electrode of a thin film transistor (TFT) connected to a reflection pixel electrode in the conventional active matrix substrate, and FIG. 14B is a waveform diagram showing the conventional signal. It is a wave form diagram of the gate signal input into the gate electrode of the thin-film transistor (TFT) connected to the pixel electrode for transmission in an active matrix substrate, (c) is the source signal input into the source electrode in the said conventional active matrix substrate (D) is a waveform diagram of a signal indicating a drain voltage applied to the reflection pixel electrode in the conventional active matrix substrate, and (e) is a transmission waveform in the conventional active matrix substrate. It is a wave form diagram of a signal showing drain voltage applied to a pixel electrode.
[Explanation of symbols]
1a ・ 1b ・ 1c ・ 1d Active matrix substrate
2 Pixel electrode
2a Reflective pixel electrode
2b Pixel electrode for transmission
3 Gate wiring
3a Reflective gate wiring (first gate wiring)
3b Transmission gate wiring (second gate wiring)
4 Source wiring
5 Thin film transistor (switching element)
5a Reflective thin film transistor (first switching element)
5b Thin film transistor for transmission (second switching element)
6 Gate electrode
6a Reflective gate electrode
6b Transmission gate electrode
7 Source electrode
7a Source electrode for reflection
7b Source electrode for transmission
8 Drain electrode
8a Reflective drain electrode
8b Drain electrode for transmission
9 Contact hole
10 Connection electrode
11 Gate insulation film
12 Auxiliary capacitance wiring
12a Reflective auxiliary capacitance wiring
12b Transmission auxiliary wiring
13 Counter substrate
14 Counter electrode
15 Transparent insulating substrate
16 Semiconductor layer
17 Doped semiconductor layer
18 Interlayer insulation film (insulation film)
19 Auxiliary capacitance electrode (conductive film)
20 Auxiliary capacitance wiring
21 Gate wiring
22 Source wiring
23 Thin film transistor (TFT)
24 Contact hole
25 Connection wiring
26 Reflection area and pixel electrode for reflection
27 Auxiliary capacitance wiring
28 Transmission area / transmission pixel electrode
29 Liquid crystal layer
P1 / P2 opening

Claims (10)

A plurality of pixel electrodes arranged in a matrix having a reflective pixel electrode for performing a reflective display and a transmissive pixel electrode for performing a transmissive display, an auxiliary capacitance element that holds the potential of the pixel electrode, and a source An active device having a source wiring for supplying a signal, a gate wiring for supplying a gate signal, and a switching element that includes a source electrode, a gate electrode, and a drain electrode and that is selected by the gate signal and supplies the source signal to the pixel electrode A matrix substrate;
A counter substrate having a counter electrode facing the reflective pixel electrode and the transmissive pixel electrode;
In a liquid crystal display device comprising a liquid crystal layer formed between the active matrix substrate and the counter substrate,
The switching element comprises a first switching element and a second switching element,
The reflection pixel electrode is connected to the first gate wiring through the first switching element,
The transmissive pixel electrode is connected to the second gate wiring through the second switching element,
The auxiliary capacitive element has a reflective auxiliary capacitive element connected to the reflective pixel electrode and a transmissive auxiliary capacitive element connected to the transmissive pixel electrode,
The amplitude of the gate signal input to the first gate wiring, the amplitude of the gate signal input to the second gate wiring, the parasitic capacitance between the gate electrode and the drain electrode of the first switching element, A parasitic capacitance between the gate electrode and the drain electrode of the second switching element; a capacitance of the liquid crystal layer between the reflective pixel electrode and the counter electrode; and a transmissive pixel electrode and the counter electrode. The capacitance of the liquid crystal layer, the capacitance of the reflection auxiliary capacitance element, and the capacitance of the transmission auxiliary capacitance element from the source signal voltage of the reflection pixel electrode potential generated when the switching element is switched. A liquid crystal display device, wherein the voltage shift amount and the voltage shift amount from the source signal voltage of the transmission pixel electrode potential are set to be the same. The parasitic capacitance between the gate electrode and the drain electrode of the first switching element is Cgd (r), the capacitance of the liquid crystal layer between the reflection pixel electrode and the counter electrode is Clc (r), and the reflection auxiliary The capacitance of the capacitive element is Ccs (r),
The parasitic capacitance between the gate electrode and the drain electrode of the second switching element is Cgd (t), the capacitance of the liquid crystal layer between the transmission pixel electrode and the counter electrode is Clc (t), and the transmission auxiliary Let Ccs (t) be the capacitance of the capacitive element,
When the amplitude of the gate signal input to the first gate wiring is ΔVg (r) and the amplitude of the gate signal input to the second gate wiring is ΔVg (t),
ΔVg (r) × Cgd (r) / (Cgd (r) + Clc (r) + Ccs (r)) = ΔVg (t) × Cgd (t) / (Cgd (t) + Clc (t) + Ccs (t))
The liquid crystal display device according to claim 1, wherein:   The liquid crystal display device according to claim 1, wherein the same gate signal is input to the first gate line and the second gate line. A plurality of pixel electrodes arranged in a matrix having a reflective pixel electrode for performing a reflective display and a transmissive pixel electrode for performing a transmissive display, an auxiliary capacitance element that holds the potential of the pixel electrode, and a source An active device having a source wiring for supplying a signal, a gate wiring for supplying a gate signal, and a switching element that includes a source electrode, a gate electrode, and a drain electrode and that is selected by the gate signal and supplies the source signal to the pixel electrode A matrix substrate;
A counter substrate having a counter electrode facing the reflective pixel electrode and the transmissive pixel electrode;
In a liquid crystal display device comprising a liquid crystal layer formed between the active matrix substrate and the counter substrate,
The switching element comprises a first switching element and a second switching element,
The reflection pixel electrode is connected to the first gate wiring through the first switching element,
The transmissive pixel electrode is connected to the second gate wiring through the second switching element,
The auxiliary capacitive element has a reflective auxiliary capacitive element connected to the reflective pixel electrode and a transmissive auxiliary capacitive element connected to the transmissive pixel electrode,
Reflection after a voltage shift from the source signal voltage of the pixel electrode potential for reflection and a voltage shift from the source signal voltage of the pixel electrode potential for transmission that occurs at the time of switching of the first switching element and the second switching element. To match the voltage of the central axis along the time axis for the voltage waveform in the pixel electrode for transmission and the pixel electrode for transmission,
The source signal voltage applied to the reflective pixel electrode via the first switching element and the second switching element are synchronized with the display timings of the reflective pixel electrode and the transmissive pixel electrode, respectively. A liquid crystal display device characterized in that a source signal voltage applied to a transmissive pixel electrode is different. The parasitic capacitance between the gate electrode and the drain electrode of the first switching element is Cgd (r), the capacitance of the liquid crystal layer between the reflection pixel electrode and the counter electrode is Clc (r), and the reflection auxiliary The capacitance of the capacitive element is Ccs (r),
The parasitic capacitance between the gate electrode and the drain electrode of the second switching element is Cgd (t), the capacitance of the liquid crystal layer between the transmission pixel electrode and the counter electrode is Clc (t), and the transmission auxiliary Let Ccs (t) be the capacitance of the capacitive element,
When the amplitude of the gate signal input to the first gate wiring is ΔVg (r) and the amplitude of the gate signal input to the second gate wiring is ΔVg (t),
The difference ΔVs between the source signal voltage applied to the reflective pixel electrode and the source signal voltage applied to the transmissive pixel electrode is:
ΔVs = ΔVg (r) × Cgd (r) / (Cgd (r) + Clc (r) + Ccs (r)) − ΔVg (t) × Cgd (t) / (Cgd (t) + Clc (t) + Ccs (t) )
The liquid crystal display device according to claim 4, wherein the following relationship is satisfied.   6. The thickness of the liquid crystal layer between the transmissive pixel electrode and the counter electrode is made larger than the thickness of the liquid crystal layer between the reflective pixel electrode and the counter electrode. 2. A liquid crystal display device according to item 1.   7. The liquid crystal according to claim 6, wherein the thickness of the liquid crystal layer between the transmissive pixel electrode and the counter electrode is twice the thickness of the liquid crystal layer between the reflective pixel electrode and the counter electrode. Display device.   8. The liquid crystal display according to claim 1, wherein a peripheral portion of the transmissive pixel electrode is overlapped by a pair of reflective pixel electrodes through one or more insulating films. apparatus. The reflection auxiliary capacitance element is formed by a reflection auxiliary capacitance wiring and a conductive film electrically connected to the reflection pixel electrode,
The transmission auxiliary capacitance element is formed by a transmission auxiliary capacitance wiring and a transmission pixel electrode,
The reflection auxiliary capacitance wiring and the transmission auxiliary capacitance wiring are the same wiring in the reflection pixel electrode and the transmission pixel electrode forming a set,
4. The liquid crystal display device according to claim 1, wherein the auxiliary capacitance wiring does not overlap with a region of the transmissive pixel electrode on which the reflective pixel electrode does not overlap. 5.   10. The liquid crystal display device according to claim 9, wherein the first gate wiring and the second gate wiring are the same wiring in the reflective pixel electrode and the transmissive pixel electrode forming a pair.

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