JP2000267633A - Liquid crystal display driving circuit, method for controlling it, and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the power consumption and to display a display picture which is flexible and good in design. SOLUTION: The liquid crystal display device is driven by applying voltage to a liquid crystal layer via a scanning electrode and a signal electrode and sets pixels corresponding to a part of all the scanning electrodes to be in a not-selected state to execute various kinds of display by using pixels corresponding to the residual scanning electrodes. Since the display selects one or plural scanning electrodes among a part of scanning electrodes and prescribed voltage previously fixed so that an effective voltage to be applied to the liquid crystal layer of pixels corresponding to the selected scanning electrode or an effective voltage per a unit time exceeds the on voltage of the pixels is applied to the selected electrode, power consumption is reduced and a display picture which is flexible and satisfactory in design can be displayed, compared with a normal driving state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display driving circuit, a method for controlling a liquid crystal display driving circuit, and a liquid crystal display device, and more particularly, to a method of non-driving a part of a display area of a liquid crystal display screen in units of scanning lines. The present invention relates to a liquid crystal display driving circuit capable of performing partial driving display in a state, a control method of the liquid crystal display driving circuit, and a liquid crystal display device.

[0002]

2. Description of the Related Art As a driving method of a conventional liquid crystal display device,
A multiplex drive system is known. In this multiplex drive system, a common electrode (= scanning electrode) and a segment electrode (= signal electrode) intersect in a matrix, and a screen is formed with these intersections as one pixel, and the common electrode is sequentially arranged for each scanning line. This is a method of performing image display by scanning.
In the liquid crystal display device adopting the multiplex drive system, a full screen drive display mode in which display is performed using all pixels of the liquid crystal screen, and a desired scan electrode (pixel) among all pixels of the liquid crystal screen in order to reduce power consumption. There is known a display having a partial drive display mode in which a display area corresponding to a scanning line is always set as a non-selection area and a display is performed using only pixels corresponding to the other remaining display areas.

More specifically, as shown in FIG. 4A, a liquid crystal display having a display area of 100 × 96 dots (the number of dots in the scanning line direction × the number of dots in the data line direction) of the liquid crystal panel. On the screen, in the full screen drive display mode, the entire display area of 100 × 96 dots is used for display as the selection area, and in the partial drive display mode, the display area of 48 × 96 dots is used for display as the selection area. In this case, as shown in FIG. 4B, the display area of 48 × 96 dots, which is
It is also possible to divide the display area into a plurality of display areas such as a display area of × 96 dots and a display area of 36 × 96 dots.

[0004]

In the above-mentioned conventional liquid crystal display device, although the power consumption can be reduced, the area not used for display is increased, which is not preferable in terms of design. However, when the display is performed by reducing the non-selection area, the power consumption increases, and the game is overturned. SUMMARY OF THE INVENTION It is an object of the present invention to provide a liquid crystal display device and a control method of the liquid crystal display device, which can display a display screen which is more flexible and preferable in design while reducing power consumption.

[0005]

According to a first aspect of the present invention, a liquid crystal layer constituting a liquid crystal display panel is driven by applying a voltage via a scanning electrode and a signal electrode. In a liquid crystal display driving circuit capable of performing various displays using pixels corresponding to some of the scanning electrodes in a non-selected state among all the scanning electrodes and using the pixels corresponding to the remaining scanning electrodes, by an external instruction. Among the partial scan electrodes, one or more scan electrodes are selected,
A forced lighting voltage applying means for applying a predetermined voltage to the selected scanning electrode such that an effective voltage applied to a liquid crystal layer of a pixel corresponding to the selected scanning electrode exceeds an on-voltage of the pixel. It is characterized by having.

According to a second aspect of the present invention, a liquid crystal layer constituting a liquid crystal display panel is driven by applying a voltage via a scanning electrode and a signal electrode, and corresponds to a part of the scanning electrodes of all the scanning electrodes. In a liquid crystal display device capable of performing various types of display using pixels corresponding to the remaining scanning electrodes by setting the pixels to a non-selected state, one or more of the scanning electrodes may be scanned by the external instruction. Selecting an electrode, and applying a predetermined voltage to the selected scan electrode such that an integral effective voltage applied to the pixel corresponding to the selected scan electrode in a unit time exceeds the on-voltage of the pixel. And a forced lighting voltage applying means.

According to a third aspect of the present invention, in the configuration of the first aspect, the forcible lighting voltage applying means is configured to invert a sign of a voltage difference between the predetermined voltage and a predetermined reference voltage every frame. The above-mentioned predetermined voltage is applied.

According to a fourth aspect of the present invention, in the configuration of the second aspect, the forcible lighting voltage applying means is configured to sign a voltage difference between the predetermined voltage and a predetermined reference voltage at a predetermined timing within one frame. The above-mentioned predetermined voltage is applied so as to be inverted.

According to a fifth aspect of the present invention, a liquid crystal layer constituting a liquid crystal display panel is driven by applying a voltage via a scanning electrode and a signal electrode, and corresponds to some of the scanning electrodes. In a control method of a liquid crystal display driving circuit capable of causing a pixel to be in a non-selected state and performing various types of display using pixels corresponding to the remaining scan electrodes, one of the scan electrodes may be operated by an external instruction. Alternatively, a plurality of scan electrodes are selected, and a predetermined voltage predetermined so that an effective voltage applied to a liquid crystal layer of a pixel corresponding to the selected scan electrode exceeds an ON voltage of the pixel is selected. And a forced lighting voltage application step of applying a voltage to the device.

According to a sixth aspect of the present invention, a liquid crystal layer constituting a liquid crystal display panel is driven by applying a voltage via a scanning electrode and a signal electrode, and corresponds to a part of the scanning electrodes of all the scanning electrodes. In a control method of a liquid crystal driving circuit capable of performing various displays using pixels corresponding to the remaining scan electrodes in a non-selected state, one or more of the partial scan electrodes are instructed by an external instruction. A plurality of scan electrodes are selected, and a predetermined voltage predetermined such that an integral effective voltage applied in a unit time to a pixel corresponding to the selected scan electrode exceeds an on-voltage of the pixel is selected. The method is characterized in that a forced lighting voltage application step of applying the voltage to the electrode is provided.

According to a seventh aspect of the present invention, there is provided a liquid crystal display panel having a scanning electrode and a signal electrode, and a liquid crystal display driving circuit according to the first or second aspect.

[0012]

Preferred embodiments of the present invention will now be described with reference to the drawings. FIG. 1 shows a schematic block diagram of a liquid crystal display device. The liquid crystal display device 10 is roughly divided into a liquid crystal display panel 11 for displaying various images, a liquid crystal driving circuit 12 for actually driving the liquid crystal display panel 11,
A liquid crystal drive voltage generation circuit 13 for generating a drive voltage used by the liquid crystal drive circuit 12 to actually drive the liquid crystal display panel 11; and a liquid crystal drive circuit based on display data input from outside and control data for various controls. 12 and a drive control circuit 14 for controlling the liquid crystal drive voltage generation circuit. The liquid crystal drive circuit 12 includes L scanning electrodes (common electrodes) CL (L = 1, L) of the liquid crystal display panel 11.
,...; And M signal electrodes (segment electrodes) SM (M = 1, 2, 3, 4,...) Of the liquid crystal display panel 11. ..; See FIG. 11). In the following description, the number of scanning lines of the liquid crystal display panel is 100 (the number of common electrodes = 100; L = 1).
To 100), and the number of signal lines is 96 (the number of segment electrodes = 96; M = 1 to 96) as an example.
When the liquid crystal display panel 11 is partially driven, it is assumed that the common voltage applied to the scanning electrodes corresponding to the non-selected areas is fixed at a predetermined voltage set in advance.

[1] First Embodiment First, as a first embodiment, a multiplex drive type liquid crystal display device will be described as an example. FIG. 2 shows a schematic configuration of a common voltage switching circuit that switches a common voltage in the scanning drive circuit 15 of the first embodiment. The common voltage switching circuit 15B is connected to a transistor switch T1 based on a control signal SC from a control unit 15A in the scanning drive circuit 15.
To T4 are turned on, and the common electrode CL (L
= 1, 2, 3, 4,...), One of the first selected voltage V0, the first non-selected voltage V4, the second selected voltage V5, and the second non-selected voltage V1. It is configured to selectively output as the common voltage VCMN. Of these four voltages, in the selected region, the first selected voltage V0, the first selected voltage V0,
One of the non-selection voltage V4, the second selection voltage V5, and the second non-selection voltage V1 is selected according to a predetermined voltage pattern, and in the non-selection region, the first non-selection voltage V4
Alternatively, the second non-selection voltage V1 is alternately selected in frame units. Further, when performing line display in a non-selection area which is a feature of the present invention, the first selection voltage V0 or the second selection voltage V5 is alternately selected in frame units. The potential relationship among the first selected voltage V0, the first non-selected voltage V4, the second selected voltage V5, and the second non-selected voltage V1 is as follows. V0>V1>V4> V5 | V0-V4 | = | V1-V5 || V0-V1 | = | V4-V5 |

[1.1] Operation of First Embodiment Next, the operation of the first embodiment will be described. The drive control circuit 14 of the liquid crystal display device 10 includes a liquid crystal drive circuit 12 and a liquid crystal drive voltage generation circuit 13 based on display data and various control data input from a control device of an external personal computer or a portable information device. Control. As a result, the liquid crystal drive voltage generation circuit 13
2 generates a drive voltage used to actually drive the liquid crystal display panel 11 and supplies the drive voltage to the liquid crystal drive circuit 12. On the other hand, the liquid crystal drive circuit 12 controls the scanning side drive circuit 15 and the signal based on the drive voltage used to actually drive the liquid crystal display panel 11 supplied from the liquid crystal drive voltage generation circuit 13 under the control of the drive control circuit 14. The side drive circuit 16 drives the liquid crystal display panel 11.

[1.2] Specific Operation of First Embodiment Next, a specific operation will be described with reference to FIG. [1.2.1] Pixel Lighting Operation in Selected Region FIG. 3A is a waveform explanatory diagram for explaining pixel lighting operation in the selected region. In FIG. 3A, for simplicity of description, the common electrode C1 and the segment electrode S1 are shown.
3 shows a voltage applied state to the liquid crystal layer forming the pixel at the intersection of the two. As shown in FIG. 3A, in the first frame forming a pair of frame groups, at a timing TC1 corresponding to the segment electrode S1, a first selection voltage V0 is applied as a common voltage, and other timings are applied. , The first non-selection time voltage V4 is applied as a common voltage. On the other hand, the data voltage V3 is applied to the segment electrodes during one frame period. As a result, the timing TC
In 1, the voltage V applied to the liquid crystal layer is V = V0−V3, and the applied voltage V is the ON voltage (VON;
As described above, the pixel is turned on. The ON voltage VON in this case is an integral effective voltage (average voltage) applied to each liquid crystal layer (the same applies hereinafter).

Thereafter, a second frame forming a pair of frame groups
In the frame, at the timing TC1 'corresponding to the segment electrode S1, the second selection voltage V5 is applied as the common voltage, and at other timings, the second non-selection voltage V1 is applied as the common voltage. On the other hand,
The segment electrode has a data voltage V2 for one frame period.
Is applied. As a result, at the timing TC1 ', the voltage V applied to the liquid crystal layer becomes V = V2-V5. In this case, the applied voltage V also becomes higher than the predetermined ON voltage (VON) of the liquid crystal layer, and It will light up.

[1.2.2] Pixel Non-Lighting Operation in Non-Selected Area FIG. 3B is a waveform explanatory diagram for explaining the pixel non-lighting operation in the non-selected area. Also in FIG.
For simplicity of description, a voltage application state to a liquid crystal layer forming a pixel at an intersection of the common electrode C1 and the segment electrode S1 is shown. As shown in FIG. 3B, in the first frame forming a pair of frame groups, a first non-selection voltage V4 is applied as a common voltage. On the other hand, the data voltage V3 is applied to the segment electrodes during one frame period. As a result, in the first frame, the voltage V applied to the liquid crystal layer is V = V4−V3, and the applied voltage V is equal to the off voltage (VOF) of the predetermined liquid crystal layer.
F; see FIG. 5) Then, the pixel is turned off. The OFF voltage VOFF in this case is an integral effective voltage (average voltage) applied to each liquid crystal layer (the same applies hereinafter). Thereafter, in the second frame forming a pair of frame groups, the second non-selection voltage V1 is used as the common voltage.
Is applied. On the other hand, the data voltage V2 is applied to the segment electrode SM during one frame period. As a result, at the timing TC1 ', the voltage V
Is V = V1−V2. In this case as well, the applied voltage V becomes equal to or lower than the predetermined off-voltage (VOFF) of the liquid crystal layer, and the pixel is turned off.

[1.2.3] Pixel Lighting Operation in Non-Selected Region FIG. 3 (c) is a waveform explanatory diagram for explaining the pixel forced lighting operation in the non-selected region, which is a feature of the present invention. FIG.
Also in (c), for simplicity of explanation, the common electrode C
The state of voltage application to the liquid crystal layer constituting the pixel at the intersection of the segment electrode S1 and the segment electrode S1 is shown. As shown in FIG. 3C, in the first frame forming a pair of frame groups, a first selection voltage V0 is applied as a common voltage. On the other hand, the data voltage V3 is applied to the segment electrodes during one frame period. As a result, in the first frame, the voltage V applied to the liquid crystal layer is as follows: V = V0−V3, and the applied voltage V is a predetermined ON voltage (VON) of the liquid crystal layer.
As described above, the pixel is always lit during the first frame period. Thereafter, the second selection voltage V5 is applied as a common voltage in the second frame forming a pair of frame groups. On the other hand, 1
The data voltage V2 is applied during the frame period. As a result, at the timing TC1 ', the voltage V applied to the liquid crystal layer becomes V = V2-V5. In this case, the applied voltage V also becomes higher than the predetermined ON voltage (VON) of the liquid crystal layer, and It will be constantly lit during the second frame period.

[1.3] Effect of the First Embodiment The above-described 3 is applied to the display of the normal drive as shown in FIG.
By performing the display control in one mode, for example, if the pixel lighting operation in the non-selection area is performed for two common electrodes, the display screen of the liquid crystal display panel has two lines as shown in FIG. Line (non-selection area forced lighting)
, Which is more preferable in terms of design. Further, in this case, in the non-selection area as shown in FIG. 4B, compared with the case where the lighting / non-lighting control is performed in the selection area as shown in FIG. According to the method of performing lighting control as described in (1), power consumption can be reduced.

More specifically, out of the 100 scanning lines of the liquid crystal display panel 11, the current consumption required for driving when 48 lines are allocated as the selection area is 10 [μA].
Assuming that, the current consumption when the display of two lines is added by the normal drive is 10 [μA] × 50 [lines] / 48 [lines] = 1
0.4 [μA]. On the other hand, the current consumption I required when performing the forced lighting as shown in FIG. 4C is as follows. The current consumption I required to drive one pixel of liquid crystal is
Assuming that the frame frequency is f, the capacitance of the liquid crystal layer is C, the applied voltage between the common electrode and the segment electrode is VCS, and the number of pixels in the horizontal direction is NPICT, then I = f ・ C ・ VCS ・ NPICT. At this time, the capacitance of the liquid crystal layer differs between the capacitance C ON when the pixel is turned on and the capacitance C OFF when the pixel is not turned on.
For example, the values are as follows. C ON = 1.0 [pF] C OFF = 0.6 [pF]

Therefore, for example, if f = 60 [Hz] and VCS = 3.8 [V], in the above example, NPICT = 96 [pixels]. The current IOFF at the time of lighting is as follows. ION = 0.02 [μA] IOFF 0.033 [μA] As a result, in the non-selected area, the difference current ΔI between when the pixel is turned on and when the pixel is turned off is ΔI = 0.02-0. 033 = 0.013 [μA]. Therefore, the current consumption when adding two lines of display is 10 [μA] +0.013 [μA] × 2 [lines] = 1.
0.026 [μA], which means that the power consumption is lower than that of the conventional driving method.

[2] Second Embodiment Next, as a second embodiment, another multiplex driving type liquid crystal display device will be described as an example. In the first embodiment, one of the positive side voltage and the negative side voltage is used as the applied voltage. However, in the second embodiment, both the positive side applied voltage and the negative side applied voltage are used as the applied voltage. This is an embodiment in which a voltage is used, and since the device configuration is the same as that of the first embodiment, detailed description will be omitted. FIG. 6 shows a schematic configuration of a common voltage switching circuit that switches a common voltage in the scanning drive circuit 15 of the second embodiment. The common voltage switching circuit 15C turns on one of the transistor switches T1 to T3 based on the control signal SC from the control unit 15A in the scanning side driving circuit 15, and applies the first selection voltage V1 to the common electrode CX. One of the selected voltage V5 and the second selected voltage -V1 is selectively output as the common voltage VCMN. Of these three voltages, in the selected region, the first selected voltage V1, the non-selected voltage V5, and the second selected voltage -V
Either 1 is selected according to a predetermined voltage pattern, and in a non-selected area, the non-selected voltage V5 is selected. Further, when performing line display in a non-selection area, which is a feature of the present invention, the first selection voltage V1 or the second selection voltage -V1 is alternately selected in frame units. The potential relationship between the first selection voltage V1, the non-selection voltage V5, and the second selection voltage -V1 is as follows. V1>V5> -V1 | V1-V5 | = | V5-(-V1) |

[2.1] Specific Operation of Second Embodiment Next, a specific operation of the second embodiment will be described. In this case, the general operation of the liquid crystal display device 10 is the same as that of the first embodiment, and a detailed description thereof will be omitted. [2.1.1] Pixel Lighting Operation in Selected Area FIG. 7A is a waveform explanatory diagram for explaining pixel lighting operation in the selected area. In FIG. 7A, for simplification of description, the common electrode C1 and the segment electrode S1 are shown.
3 shows a voltage applied state to the liquid crystal layer forming the pixel at the intersection of the two. In the following description, as shown in FIG. 7A, in a first frame forming a pair of frame groups, a timing TC1 corresponding to the segment electrode S1 is set.
In this case, the first selection voltage V1 is applied as the common voltage, and the non-selection voltage V5 is applied as the common voltage at other timings. On the other hand, the data voltage V4 is applied to the segment electrodes during one frame period.

As a result, at the timing TC1, the voltage V applied to the liquid crystal layer is V = V1-V4, and the applied voltage V is equal to the ON voltage (VON) of the predetermined liquid crystal layer.
As described above, the pixel is turned on. afterwards,
In the second frame forming a pair of frame groups,
At the timing TC1 'corresponding to the segment electrode S1,
The second selection voltage -V1 is applied as the common voltage, and the non-selection voltage V4 is applied as the common voltage at other timings. On the other hand, 1
The data voltage -V4 is applied during the frame period. As a result, at the timing TC1 ', the voltage V applied to the liquid crystal layer becomes V = -V4-(-V1), and the applied voltage V in this case is also equal to or higher than the ON voltage (VON) of the predetermined liquid crystal layer. This turns on the pixel.

[2.1.2] Non-Lighting Operation of Pixels in Non-Selected Area FIG. 7B is a waveform explanatory diagram for explaining a pixel lighting operation in the selected area. Also in FIG. 7B, for simplicity of description, the common electrode C1 and the segment electrode S1 are shown.
3 shows a voltage applied state to the liquid crystal layer forming the pixel at the intersection of the two. As shown in FIG. 7B, in the pixel non-lighting operation in the non-selection area, the non-selection voltage V5 is applied as the common voltage in the first frame and the second frame forming a pair of frame groups. On the other hand, the data voltage V4 is applied to the segment electrodes during the first frame period. As a result, the voltage V applied to the liquid crystal layer in the first frame is V = V5−V4, and the applied voltage V is equal to the off voltage (VOF) of the predetermined liquid crystal layer.
F) At this point, the pixel is turned off. After that, in the second frame, 1 is applied to the segment electrodes.
The data voltage -V4 is applied during the frame period. As a result, at the timing TC1 ', the voltage V applied to the liquid crystal layer becomes V = V5-(-V4). In this case as well, the applied voltage V becomes lower than the predetermined off-voltage (VOFF) of the liquid crystal layer. The pixel is turned off.

[2.1.3] Pixel Lighting Operation in Non-Selected Region FIG. 7 (c) is a waveform explanatory diagram for explaining the pixel forced lighting operation in the non-selected region, which is a feature of the present invention. FIG.
Also in (c), for simplicity of explanation, the common electrode C
The state of voltage application to the liquid crystal layer constituting the pixel at the intersection of the segment electrode S1 and the segment electrode S1 is shown. As shown in FIG. 7B, in the first frames forming a pair of frame groups, the first selection voltage V1 is applied as a common voltage. On the other hand, the data voltage V4 is applied to the segment electrodes during one frame period. As a result, in the first frame, the voltage V applied to the liquid crystal layer is as follows: V = V1−V4, and the applied voltage V is the ON voltage (VON) of the predetermined liquid crystal layer.
As described above, the pixel is always lit during the first frame period. Thereafter, in the second frame forming a pair of frame groups, the second selection voltage -V1 is applied as a common voltage. On the other hand, the segment electrodes
Data voltage -V4 is applied during one frame period. As a result, at the timing TC1 ', the voltage V applied to the liquid crystal layer is V = -V4-(-V1), and the applied voltage V in this case is also equal to or higher than the ON voltage (VON) of the predetermined liquid crystal layer. As a result, the pixel is always lit during the second frame period.

[2.2] Effects of the Second Embodiment According to the second embodiment, the display control in the above three modes is performed on the display of the normal drive as shown in FIG. 4B. For example, if the pixel lighting operation in the non-selected region is performed for two common electrodes, two lines can be drawn on the display screen of the liquid crystal display panel as shown in FIG. It becomes more preferable. Further, also in this case, compared with the case where the lighting / non-lighting control is performed in the selection area as shown in FIG. 4A, the lighting control in the non-selection area as shown in FIG. According to this, power consumption can be reduced.

[3] Third Embodiment In each of the above embodiments, the liquid crystal is driven by the multiplex method. However, in the third embodiment, the liquid crystal is driven by the multi-line scan (MLS) method. FIG. The multi-line scanning method is a driving method that sequentially scans a plurality of common electrodes while simultaneously scanning a plurality of common electrodes, unlike the multiplex method. For example, the details are disclosed in International Application No. WO93 / 18501. In the third embodiment, the device configuration will be described as being the same as the first embodiment in FIG.

[3.1] Pixel lighting in selected area /
Non-Lighting Operation Next, the pixel lighting / non-lighting operation in the selected area will be described. First, the outline of the pixel lighting / non-lighting operation in the selected area will be described. FIGS. 8A to 8D schematically show driving waveforms when the common electrode is scanned every four lines in such a multi-line scanning method. FIG.
In (d), for simplicity of illustration, among all the common electrodes CL (L = 1, 2, 3, 4,...), The common electrodes C1 to C
Although the waveform of the selection period in FIG. 4 is illustrated as a rectangular wave, in actuality, as will be described later, other common electrodes driven simultaneously (for example, common electrodes C1, C3, and C4 with respect to common electrode C2). Has a complicated waveform in consideration of the potential state of Also, the waveform of the segment electrode S1 is shown so as not to change during one frame, but actually, as will be described later, four common electrodes that are simultaneously scanned (common in the above example, The pixel has a complicated waveform corresponding to the lighting and non-lighting of the pixel corresponding to the electrodes C1 to C4) and the voltage waveform applied to the common electrode. For example, in the liquid crystal layer to which a voltage is applied by the common electrode C2 and the segment electrode S1, the integrated value of the voltage difference between the applied voltage of the common electrode C1 and the applied voltage of the segment electrode S1 that changes every moment on the time axis ( Lighting or non-lighting depending on the effective voltage).

[3.1.1] Specific Example of Pixel Lighting / Non-Lighting Operation in Selected Area Next, the pixel lighting / non-lighting operation in the selected area will be specifically described with reference to FIGS. 1, 11 and 12. I do.
As shown in FIG. 11, the liquid crystal display device 10 includes a plurality of common electrodes C1, C2,.
, And a plurality of segment electrodes S1, S2,...
A liquid crystal layer is interposed between the substrate and the substrate having SM. The scanning side driving circuit 15 of the liquid crystal driving circuit 12 outputs a scanning signal to the common electrode C in order to drive the liquid crystal display panel 11, and the signal side driving circuit 16 outputs a data signal to the segment electrode S. Output. Next, the driving operation of the liquid crystal display device 10 having the above configuration will be described in more detail. Here, of the plurality of common electrodes C, three scanning electrodes are simultaneously selected sequentially, and the display as shown in FIG. 11 is performed on the liquid crystal display panel 11. That is,
The first three common electrodes C1, C2, C3 For the selection period t1
Then, a scanning signal as shown in FIG. 12A is applied to these common electrodes C1, C2, and C3, and a predetermined data signal is applied to the segment electrode S at the same time. Next, the common electrodes C4, C5, C6 And a scanning signal as shown in FIG. 12B is applied to these electrodes in the same manner as described above, and a data signal is applied to the segment electrode S at the same time. Then, this is sequentially repeated until all the common electrodes C in FIG. 11 are selected as one frame. further,
The waveform of each scanning signal indicates the number of selected common electrodes C by h.
In this case, a waveform having a pulse pattern number of 2 ^h in units of a time Δt in one selection period t1 is used.

For example, as shown in FIG. 12, a scanning signal formed when three common electrodes C are selected is divided by a time Δt which divides the selection period t1 into eight (2 ³ = 8). , At the beginning time Δt, the common electrode C1
Is turned off, the common electrode C2 is turned off, and the common electrode C3 is turned off. At the next time Δt, the common electrode C1 is turned off, the common electrode C2 is turned off, and the common electrode C3 is turned on. The waveform formed is used. The data signal applied to the segment electrode S is determined by ON / OFF of each dot to be displayed simultaneously (3 dots in the case of simultaneous driving of three lines) and the voltage value of the scanning signal applied to the common electrode C. You. For example,
When the waveform of the scanning signal applied to the simultaneously selected common electrodes C1, C2, C3 is a positive pulse, it is turned on, and when it is a negative pulse, it is turned off. The on / off of the display data is compared for each pulse. The data signal is set according to the number of mismatches. Specifically, in the waveform of the scanning signal to the common electrodes C1, C2, and C3 in FIG. 11, when the voltage of V2 is applied, the ON state is applied, and when the voltage of MV2 is applied, the OFF state is selected. When the black circle is turned on and the white circle is turned off, the segment electrode S1 in FIG.
The display of pixels that intersect with the common electrodes C1, C2, and C3 is turned on / off in order. On the other hand, the initial voltages of the pulse patterns applied to the common electrodes C1, C2, and C3 are off, off, and off, respectively. When these two are compared in order, the number of mismatches is two, and therefore the first pulse pattern of the segment electrode S1 includes FIG.
A voltage V2 as shown in FIG.

As described above, in FIG. 12, MV2 when the number of mismatches is 0, MV1 when it is 1 and V when it is 2
At the time of 1 and 3, the pulse voltage of V2 is applied. The voltage ratio between V1 and V2 is set so that V1: V2 = 1: 2. Also, the common electrodes C1, C2,
The second pulse pattern of the voltage applied to C3 is off, off, and on, respectively. When the display of the pixels is sequentially compared with on, on, and off, all of them are inconsistent and the number of inconsistencies is three. The voltage V2 is applied to the second pulse of the segment electrode S1. Similarly, V1 is applied to the third pulse, MV1 is applied to the fourth pulse, and MV2, V1, MV1, and MV1 are applied in this order. Further, when the next common electrodes C4 to C6 are selected and the voltages shown in FIG. 12B are applied to the common electrodes C4 to C6, the pixels of the pixels where the respective common electrodes C4 to C6 intersect with the signal electrodes are selected. ON / OFF display and the common electrodes C4 to C6
A data signal of a voltage level corresponding to the mismatch of the applied voltage to the ON / OFF of each pulse pattern is applied as shown in FIG. FIG. 12D shows the common electrode C.
This is a waveform applied to a pixel where 1 and the segment electrode S1 intersect, that is, a composite waveform of a scanning signal applied to the common electrode C1 and a data signal applied to the segment electrode S1. As described above, in the multi-line scanning method in which a plurality of scanning electrodes are sequentially selected and driven simultaneously, an on / off ratio is realized, and the driving voltage can be suppressed low.

[3.2] Schematic Configuration of Non-Selection Common Voltage Switching Circuit FIG. 9 is a schematic configuration diagram of the non-selection common voltage switching circuit in the scanning side drive circuit 15 for switching the non-selection common voltage. The non-selection common voltage switching circuit 15D turns on one of the transistor switches T1 to T3 based on the control signal SC from the control unit 15A in the scanning side drive circuit 15, and supplies the non-selection voltage VC to the common electrode CX. , First
The selected voltage V2 and the second selected voltage MV2 are selectively output as the common voltage VCMN. Among these three voltages, in the selection region, one of the first selection voltage V2, the non-selection voltage VC and the second selection voltage MV2 is selected according to a predetermined voltage pattern,
In the non-selection region, the non-selection time voltage VC is selected. Further, when performing line display in a non-selection area, which is a feature of the present invention, the first selection voltage V2 or the second selection voltage MV2 is alternately selected in 1/2 frame units.
Note that the unit of フ レ ー ム frame is that control is easy and power consumption is small (because the frequency is low).
It is not necessary to limit to this, and it is possible to adopt a configuration in which selection is made alternately in 1/2 ⁿ frame units such as 1/4 frame unit, 1/8 frame unit,... In this case, the potential relationship between the first selection voltage V2, the non-selection voltage VC, the second selection voltage MV2, and the voltages V1 and MV1 is as follows. V1 = V2 / 2 MV1 = MV2 / 2 V2>VC> MV2 | V2-VC | = | VC-MV2 |

[3.3] Specific Operation of Third Embodiment Next, a specific operation of the third embodiment will be described. In this case, the general operation of the liquid crystal display device 10 is the same as that of the first embodiment, and a detailed description thereof will be omitted. Further, in the following description, for simplification of the description, a description will be given focusing on a voltage application state to a liquid crystal layer forming a pixel at an intersection of the common electrode C1 and the segment electrode S1.

[3.3.1] Non-Lighting Operation of Pixels in Non-Selected Area As described above, the waveform of the segment electrode S1 indicates the lighting, non-lighting, and common electrode of the pixels corresponding to the common electrodes C1 to C4 which are simultaneously scanned. Is a complicated waveform corresponding to the applied voltage waveform. Therefore, the effective voltage (= integral effective voltage) between the common electrode C1 and the predicted waveforms of all the segment electrodes S1 should not exceed the ON voltage. For this reason, in the pixel non-lighting operation in the non-selection region, as shown in FIG. 9A, the non-selection time voltage VC is applied as the common voltage in the first frame and the second frame forming a pair of frame groups. Is done. On the other hand, common electrodes C1 to C4 which are simultaneously scanned are attached to the segment electrode S1.
Is applied, and a voltage based on a waveform corresponding to the lighting and non-lighting of the pixel corresponding to (a) and a voltage waveform applied to the common electrode (in FIG. 10A, V1 is shown as an average voltage) is applied.

As a result, the voltage V applied to the liquid crystal layer in the first frame becomes V ≒ V1−VC, and the applied voltage V is a predetermined off-voltage (VOF) of the liquid crystal layer.
F) At this point, the pixel is turned off. Thereafter, in the second frame, a voltage based on a waveform (FIG. 10A) corresponding to the common electrodes C1 to C4, which are simultaneously scanned, is turned on and off, and the voltage applied to the common electrode is applied to the segment electrodes. In this example, MV1 is shown as the average voltage.). As a result, the voltage V applied to the liquid crystal layer in the first frame becomes V ≒ VC−MV1, and the applied voltage V is the off-state voltage (VOF) of the predetermined liquid crystal layer.
F) At this point, the pixel is turned off.

[3.3.2] Pixel Lighting Operation in Non-Selected Region FIG. 10 (b) is a waveform explanatory diagram for explaining the pixel forced lighting operation in the non-selected region, which is a feature of the present invention. FIG. 10B also shows a voltage application state to the liquid crystal layer forming the pixel at the intersection of the common electrode C1 and the segment electrode S1 for simplification of the description. FIG. 10 (b)
As shown in (1), in the first half of the first frame forming a pair of frame groups, the second selection voltage MV2 is applied as a common voltage, and in the second half, the first selection voltage V2 is applied as a common voltage. Is done. On the other hand, the segment electrode has a voltage based on a waveform corresponding to the lighting and non-lighting of the pixels corresponding to the common electrodes C1 to C4 which are simultaneously scanned and a waveform corresponding to the voltage applied to the common electrode (in FIG. V1 is illustrated).

As a result, in the first half of the first frame, the voltage V applied to the liquid crystal layer is V ≒ V1−MV2, and the applied voltage V, which is an effective voltage per unit time (= 1 frame), is a predetermined voltage. When the voltage becomes equal to or higher than the ON voltage (VON) of the liquid crystal layer, the pixel is constantly lit during the first half period of the first frame. Further, in the latter half of the first frame, the voltage V applied to the liquid crystal layer becomes V1MV1−V1, and the applied voltage V, which is the effective voltage per unit time (= 1 frame), turns on the predetermined liquid crystal layer. When the voltage becomes equal to or higher than the voltage (VON), the pixel is constantly turned off during the latter half of the first frame. Further, as shown in FIG. 10B, in the first half of the second frame forming the pair of frame groups, the second selection voltage MV2 is applied as a common voltage, and in the second half, the first voltage is applied as the common voltage. At the time of selection, the voltage V2 is applied. On the other hand, the segment electrode has a voltage based on a waveform corresponding to the lighting and non-lighting of the pixels corresponding to the common electrodes C1 to C4 which are simultaneously scanned and a waveform corresponding to the voltage applied to the common electrode (in FIG. V1 is illustrated).

As a result, in the first half of the first frame, the voltage V applied to the liquid crystal layer is V ≒ V 1 −MV 2, and the applied voltage V, which is the effective voltage per unit time (= 1 frame), is a predetermined value. When the voltage becomes equal to or higher than the ON voltage (VON) of the liquid crystal layer, the pixel is constantly lit during the first half period of the second frame. Further, in the latter half of the first frame, the voltage V applied to the liquid crystal layer becomes V1MV1−V1, and the applied voltage V, which is the effective voltage per unit time (= 1 frame), turns on the predetermined liquid crystal layer. When the voltage becomes equal to or higher than the voltage (VON), the pixel is constantly turned off during the latter half of the second frame. As a result, when the user visually recognizes the pair of frame groups, a line corresponding to the common electrode is displayed on the liquid crystal display panel 11 by an afterimage effect.

[3.4] Effects of Third Embodiment According to the third embodiment, display control in the above three modes is performed on the display of the normal drive as shown in FIG. 4B. Thus, for example, if the pixel lighting operation in the non-selection region is performed for two common electrodes, two lines can be drawn on the display screen of the liquid crystal display panel as shown in FIG. This is more preferable in terms of design. Further, also in this case, compared with the case where the lighting / non-lighting control is performed in the selection area as shown in FIG. 4A, the lighting control in the non-selection area as shown in FIG. According to this, power consumption can be reduced.

[4] Effects of the Embodiments As described above, according to each embodiment, even when partial driving is performed, the degree of freedom in the design of the display screen can be increased without unnecessarily increasing power consumption. Thus, it is possible to perform a more preferable screen display for the user.
Furthermore, compared to the case where the compulsory pixel lighting operation is not performed in the non-selected area, the power consumption does not change much, so that it can benefit from partial driving and can be driven for a long time in battery-powered information devices and the like. Become.

[0042]

As described above, according to the present invention,
Since the voltage applied to the scan electrode corresponding to the pixel in the non-selected state is set so that the effective applied voltage of the pixel exceeds the ON voltage of the pixel, the power consumption of the pixel along the selected scan electrode is reduced. The lighting state can be set without increasing. Therefore, it is possible to display a more flexible and design-friendly display screen while reducing power consumption.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of a main part of a liquid crystal display device according to an embodiment.

FIG. 2 is a schematic configuration diagram of a common voltage switching circuit according to the first embodiment.

FIG. 3 is an operation explanatory timing chart of the first embodiment.

FIG. 4 is an explanatory diagram of a screen display example according to the embodiment;

FIG. 5 is an explanatory diagram of an ON voltage and an OFF voltage of each pixel.

FIG. 6 is a schematic configuration diagram of a common voltage switching circuit according to a second embodiment.

FIG. 7 is an operation explanatory timing chart of the second embodiment.

FIG. 8 is a timing chart (part 1) for explaining the operation of the third embodiment.

FIG. 9 is a schematic configuration diagram of a non-selected common voltage switching circuit according to a third embodiment.

FIG. 10 is a timing chart (part 2) for explaining the operation of the third embodiment.

FIG. 11 is a diagram illustrating a specific operation of the third embodiment.

FIG. 12 is a timing chart illustrating a specific operation of the third embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Liquid crystal display device 11 ... Liquid crystal display panel 12 ... Liquid crystal drive circuit 13 ... Liquid crystal drive voltage generation circuit 14 ... Drive control circuit 15 ... Scan side drive circuit 15B, 15C ... Selection common voltage switching circuit 15D ... Non-selection common voltage Switching circuit 16 ... Signal side drive circuit

Continued on the front page F term (reference) 2H093 NA06 NA18 NA22 NA33 NA34 NA43 NA47 NB30 NC03 NC59 ND39 NH18 5C006 AB05 AC23 AC24 BB12 BC03 FA47 5C080 AA10 BB05 BB06 CC07 DD01 DD26 EE01 EE32 FF10 FF13 JJ01 JJ02 JJ05 JJ03

Claims (7)

[Claims] 1. A liquid crystal layer constituting a liquid crystal display panel is driven by applying a voltage via a scanning electrode and a signal electrode, and a pixel corresponding to a part of the scanning electrodes among all the scanning electrodes is set to a non-selected state. In a liquid crystal display drive circuit capable of performing various displays using pixels corresponding to the remaining scan electrodes, one or more scan electrodes are selected from the partial scan electrodes by an external instruction, A forced lighting voltage applying means for applying a predetermined voltage to the selected scanning electrode such that an effective voltage applied to a liquid crystal layer of a pixel corresponding to the selected scanning electrode exceeds an on-voltage of the pixel. A liquid crystal display driving circuit, comprising: 2. A method of driving a liquid crystal layer constituting a liquid crystal display panel by applying a voltage through a scanning electrode and a signal electrode, and setting a pixel corresponding to a part of the scanning electrodes of all the scanning electrodes to a non-selected state. In a liquid crystal display device capable of performing various displays using pixels corresponding to the remaining scan electrodes, one or more scan electrodes are selected from the partial scan electrodes by an external instruction, and Forcible lighting voltage applying means for applying a predetermined voltage to the selected scan electrode so that the integral effective voltage applied to the pixel corresponding to the selected scan electrode in a unit time exceeds the ON voltage of the pixel. A liquid crystal display drive circuit, comprising: 3. The liquid crystal display driving circuit according to claim 1, wherein the forcible lighting voltage applying means is configured to invert the sign of a voltage difference between the predetermined voltage and a predetermined reference voltage every frame. A liquid crystal display driving circuit characterized by applying a voltage of 4. The liquid crystal display driving circuit according to claim 2, wherein said forced lighting voltage applying means inverts a sign of a voltage difference between said predetermined voltage and a predetermined reference voltage at a predetermined timing in one frame. Liquid crystal display driving circuit, wherein the predetermined voltage is applied as described above. 5. A liquid crystal layer constituting a liquid crystal display panel is driven by applying a voltage via a scanning electrode and a signal electrode, and a pixel corresponding to a part of the scanning electrodes among all the scanning electrodes is set to a non-selected state. In a control method of a liquid crystal display drive circuit capable of performing various displays using pixels corresponding to the remaining scan electrodes, one or more scan electrodes of the partial scan electrodes are controlled by an external instruction. A forced lighting voltage for selecting and applying a predetermined voltage to the selected scan electrode so that an effective voltage applied to a liquid crystal layer of a pixel corresponding to the selected scan electrode exceeds an on-voltage of the pixel. A method for controlling a liquid crystal display drive circuit, comprising an applying step. 6. A liquid crystal layer constituting a liquid crystal display panel is driven by applying a voltage via a scanning electrode and a signal electrode, and a pixel corresponding to a part of the scanning electrodes among all the scanning electrodes is set to a non-selected state. In a control method of a liquid crystal drive circuit capable of performing various displays using pixels corresponding to the remaining scan electrodes, one or more scan electrodes are selected from the partial scan electrodes by an external instruction. And forcibly lighting a predetermined voltage applied to the selected scan electrode such that an integral effective voltage applied to the pixel corresponding to the selected scan electrode within a unit time exceeds the ON voltage of the pixel. A method for controlling a liquid crystal display drive circuit, comprising a voltage application step. 7. A liquid crystal display device comprising: a liquid crystal display panel having a scanning electrode and a signal electrode; and the liquid crystal display driving circuit according to claim 1 or 2.