JP3497986B2 - Driving method of liquid crystal display element and liquid crystal display device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of driving a liquid crystal display device and a liquid crystal display device, and more particularly to a liquid crystal display device having high contrast and high brightness and free from the influence of electrical asymmetry. The present invention relates to a driving method and a liquid crystal display device in which a liquid crystal display element is driven by such a driving method.

[0002]

At present, the mainstream high-performance liquid crystal display, active matrix liquid crystal display device of use are TN (twisted nematic) mode or IPS (in-plane switching) mode of a TFT (thin film transistor) mode nematic liquid crystal . In these active matrix liquid crystal display devices, an image signal is normally rewritten at 60 Hz in order to write positive and negative at 30 Hz, and one field time is about 16.7 ms (millisecond) (both positive and negative fields). The total time is called one frame and is about 33.3 ms). On the other hand, the response speed of the liquid crystal is the frame time, that is, about 33.3 ms, even if it is the fastest at present. Therefore, when displaying a video signal composed of a moving image or displaying a high-speed computer image, a liquid crystal response speed faster than the current frame time is required.

By the way, in order to achieve higher definition, the backlight, which is the illumination light of the liquid crystal display device, is changed to red light.
Field-sequential color liquid crystal display devices that are switched between green and blue over time are also under consideration. In this method, it is not necessary to spatially arrange the color filters, and therefore, it is possible to achieve a resolution three times higher than the conventional one. In the field-sequential color liquid crystal display device, it is necessary to display one color in 1/3 of the time for one field, and therefore, the time available for display is about 5 ms. Therefore, the liquid crystal itself is required to respond faster than 5 ms. Liquid crystals having spontaneous polarization, such as ferroelectric liquid crystals and antiferroelectric liquid crystals, have been studied as liquid crystals capable of realizing such high-speed response. Also in the nematic liquid crystal, or by increasing the dielectric anisotropy, or to lower the viscosity, or thin, high-speed due to change the liquid crystal alignment like the orientation of pi has been studied.

On the other hand, in the active matrix liquid crystal display element, the time when the voltage and the electric charge are actually written in the liquid crystal portion is only the selection time (writing time) of each scanning line.
This time is 16.7 μs (microseconds) when writing is performed in one field time with 1000 lines, and is about 5 μs when field sequential driving is performed. At present, there are almost no liquid crystals or liquid crystal usage forms in which the response ends within this time. Even in the above-mentioned liquid crystal having spontaneous polarization and the nematic liquid crystal which has been sped up, there is no known element that exhibits such a quick response.

As a result, the following problems occur because the liquid crystal responds after the signal writing is completed. First, in a liquid crystal having spontaneous polarization, a counter electric field is generated due to the rotation of the spontaneous polarization, and the voltage across the liquid crystal layer drops sharply. Therefore, the voltage written on both ends of the liquid crystal layer changes greatly. Further, even in a high-speed nematic liquid crystal, the capacitance change of the liquid crystal layer due to the dielectric anisotropy becomes extremely large, so that the holding voltage to be written and held in the liquid crystal layer changes. Such a decrease in holding voltage, that is, a decrease in effective applied voltage is
Writing becomes insufficient and the contrast is lowered. Further, when the same signal is continuously written, the brightness keeps changing until the holding voltage does not drop, and it takes several frames to obtain stable brightness.

Further, as shown in pages 720 to 729 of No. 2 of Part 1 of the 36th volume of Japanese Applied Physics, the same applies from the frame in which the image signal changes and the absolute value of the signal voltage changes. A phenomenon called "step response" is observed when the image signal is continuously written over several frames. This phenomenon occurs for several frames for the AC drive signal voltage of the same amplitude,
This is a phenomenon in which the transmittance vibrates brightly and darkly, and after that, the amount of transmitted light becomes stable at a constant level. An example of this phenomenon is shown in the schematic view of FIG. FIG. 12A is a waveform diagram of the data voltage, FIG.
12B is a waveform diagram of the gate voltage, and FIG. 12C is a waveform diagram of the transmittance at that time.

FIG. 13 is a timing chart for each scanning line in the driving shown in FIG. 12, in which the shades of the positive and negative display periods 102 and 104 are the brightness based on the transmittance shown in FIG. Represent. Moreover, in FIG. 13, the time of 16.7 ms is shown by the arrow. In FIG. 13, six scanning lines are assumed, and positive writing 101 is sequentially performed from the upper scanning line to obtain a positive display 102, and then negative writing 103 is sequentially performed from the upper scanning line. To obtain the negative display 104.
For each scanning line, the period of positive writing 101 and positive display 102 is added to the first field, negative writing 103
The period of the negative display 104 is added to the second field, and the total of both fields is one frame. Now, applying the data voltage of FIG. 12 (a),
When the TFT switch is turned on with the gate voltage of
As shown in (c), the transmittance vibrates bright and dark for each field. Such vibration of the transmittance is observed as flicker, which causes deterioration of display quality. In addition, as shown in FIG. 12C, a constant transmittance is settled in the second frame (4 fields) after the signal voltage is applied. As a result, the brightness change also vibrates as shown in FIG. As described above, even if a high-speed response liquid crystal is used, it takes several frames to stabilize the actual brightness, and thus the high speed of the displayed image is lost.

On the other hand, the transmittance after the liquid crystal response is determined not by the applied signal voltage but by the amount of electric charge stored in the liquid crystal capacitance after the liquid crystal response. This charge amount is determined by the accumulated charge before writing a predetermined signal and the newly written write charge. Further, the accumulated charge after this response also changes depending on the pixel design values such as the physical property constant of the liquid crystal, the electrical parameter, and the storage capacitance. Therefore, in order to obtain the correspondence between the signal voltage and the transmittance, information for calculating (1) the correspondence between the signal voltage and the write charge, (2) the accumulated charge before the writing, and (3) the accumulated charge after the response is obtained. And actual calculation processing etc. are required. As a result, a frame memory for storing (2) over the entire screen and a calculation unit for (1) or (3) are required. This leads to an increase in the number of parts of the system and is not preferable.

As a method for solving these problems, a reset pulse method for applying a reset voltage for aligning a predetermined liquid crystal state before writing new data is often used.
Used. As an example, the technique described on pages L-66 to L-69 of IDR 1997 will be described. In this document, an OCB (Optical Compensated Birefligence) mode in which a compensating film is added to a nematic liquid crystal having a pie orientation is used. The response speed of this liquid crystal mode is about 2
It is set to 5 to 5 milliseconds, which is significantly faster than the conventional TN mode. Originally, the response should be completed within one frame, but as described above, it takes several frames until a stable transmittance is obtained due to a large decrease in the holding voltage due to the change in the dielectric constant due to the response of the liquid crystal. Therefore, in the above-mentioned literature,
A method for writing a black display after writing a white display within one frame is shown in FIG. 5 of the document. This figure is shown in FIG.
Quote as. The horizontal axis represents time and the vertical axis represents luminance. The dotted line shows the luminance change in the case of normal driving, and the stable luminance is reached in the third frame. On the other hand, according to the reset pulse method, since a predetermined state is always established when new data is written, there is a one-to-one correspondence of a constant transmittance with respect to the written constant signal voltage. This one-to-one correspondence greatly simplifies the mechanism of generating the driving signal and eliminates the need for a means such as a frame memory for storing the previous write information.

As another means for solving these problems, one of the digests of AMLC 97 is used.
A driving method called "pseudo DC driving" shown on pages 19 to 122 has been proposed. This technique will be described with reference to FIG. 15 is similar to FIG.
15A is a waveform diagram of the data voltage, FIG. 15B is a gate voltage, and FIG. 15C is a waveform diagram of the transmittance at that time. 16 is a timing chart for each scanning line, and the shades of the positive and negative display periods 102 and 104 are shown in FIG.
It represents the luminance based on the transmittance of 5 (c). In addition, FIG.
The time of 16.7 ms is shown by the arrow. In the description in the literature, 16.7 ms is defined as one frame time, but since this definition is not general, it is changed in the figures in this specification (the one frame time described in the literature is It corresponds to one field time in the specification as compared with the usual prior art).

In the "pseudo DC drive", unlike the normal AC drive shown in FIG. 12, the data voltage of the same sign is continuously applied during a plurality of fields. After a plurality of fields, the sign of the data voltage is inverted to eliminate electrical bias. In FIG. 15, after the positive writing of 4 fields, the negative writing of 4 fields is performed, and the display of one image signal ends. The timing of writing for each scanning line is as shown in FIG. 16, and positive data is sequentially written from the top, repeated four times, and then negative data is sequentially written from the top four times. With this method, a state can be obtained in which the constant DC voltage applied is the same as the holding voltage across the liquid crystal.
As a result, the holding voltage does not decrease due to the response of the liquid crystal, and the final transmittance is higher than that in the method of AC driving in FIG. However, one frame time in this method is the total of a plurality of frames of each code. That is, in the example of FIG. 15, one frame time of this method is four times as long as that of the frame of FIG.

[0012]

As described above, the method of comparing the accumulated charges before and after writing requires the comparison operation unit and the like in addition to the frame memory, which causes an increase in the system. Further, in the method using the reset pulse, a reset period for keeping a constant state is required, and thus the writing and displaying time is substantially shortened. Further, since there is always a period in which the transmittance is constant, flicker is likely to occur. That is, in the reset pulse method, the contrast is deteriorated due to the in-plane distribution of brightness, flicker, and the decrease or increase of the average brightness. On the other hand, in the pseudo DC drive, as described above, a longer frame time (see FIG.
5 and FIG. 16 require 4 times the AC drive), and high-speed response cannot be utilized. Further, as a result, a long period flicker that vibrates at a multiple of the normal frame time (16.7 ms) as shown in FIG. 16 is generated.

Therefore, an object of the present invention is to provide a method for driving a liquid crystal display device in which a one-to-one correspondence between applied signal voltage and transmittance can be seen without using a reset pulse method or a frame memory. is there. Another object of the present invention is to provide a driving method of a liquid crystal display device, which has a one-to-one correspondence between an applied signal voltage and a transmittance and is capable of high-speed response. Another object is to provide a liquid crystal display device using those driving methods.

[0014]

In order to achieve the above object, a method for driving a liquid crystal display device according to the present invention (hereinafter, referred to as a first method).
Driving method), one frame is composed of a first field and a second field, data is written plural times with a predetermined signal voltage in the first field, and then the sign of the signal voltage is written in the second field. The feature is that the data is inverted and the data is written plural times.

Another driving method of the liquid crystal display element according to the present invention (hereinafter, referred to as a second driving method) is a signal voltage in which the polarity is inverted between positive and negative in a predetermined cycle, so that data is plural times in one frame. It is characterized by writing.

In the third and fourth driving methods, the scanning line group is divided into a plurality of blocks and the plurality of blocks are simultaneously scanned by the first and second invention methods, respectively.

Further, in the fifth and sixth driving methods, one frame is divided into three fields according to three colors, and data is sequentially displayed in each field to drive a field sequential liquid crystal display device. Method,
The driving method for each color is characterized by the third or fourth driving method.

The first driving method corresponds to the above-described pseudo DC driving method in which the frequency is increased.
Writing is performed multiple times in one field by C drive.
The second driving method corresponds to the method in which the frequency of AC driving is increased, and AC driving of a plurality of cycles is performed during one frame.
The third driving method is the first driving method, in which the scanning line is divided into a plurality of blocks and scanning is performed simultaneously. The fourth driving method is a method of dividing the scanning line into a plurality of blocks by the second driving method and simultaneously scanning. A fifth driving method of the present invention is a field sequential display, the same driving as the first and third driving methods is performed, and each color is positive plural times writing, display period and negative plural writing. And the display period. A sixth driving method of the present invention is a field sequential display, is similar to the driving methods of the second and fourth driving methods, and is configured by AC driving of a plurality of times and a display period. The liquid crystal display device according to the present invention,
It is a liquid crystal display device using the first to fourth driving methods.
Another liquid crystal display device according to the present invention is the fifth and sixth liquid crystal display devices.
A field-sequential liquid crystal display device using the above driving method, which cancels the viewing angle dependence of the liquid crystal display mode and the in-plane luminance distribution due to the driving method.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described specifically and in detail with reference to the accompanying drawings. Embodiment 1 This embodiment is an example of an embodiment of a first driving method of a liquid crystal display element according to the present invention, FIG. 1A is a waveform diagram of a voltage applied to a data line, FIG. ) Is a waveform diagram of the voltage applied to the gate line, and FIG.
It is a figure which shows the transmittance | permeability change at the time of applying the voltage shown to (a) and (b). In one aspect, this embodiment example is a pseudo DC.
This corresponds to an increase in the frequency of the driving method, and from another viewpoint, it corresponds to writing multiple times in one field by AC driving. Specifically, the voltage applied to the data line in FIG. 1A is a rectangular wave that forms one frame in two fields of 16.7 ms, which is the same as in the AC drive in FIG. On the other hand, the voltage applied to the gate line in FIG. 1B is applied multiple times (4 times in this figure) during one field period.
On) pulse. As a result, FIG. 1 (c)
As shown in the change in transmittance, 1 field is 16.7 ms.
In the meantime, the transmittance gradually increases according to the number of writings, and
The stable state is reached by the second writing.

FIG. 2 is a diagram showing a time chart for each scanning line and a display brightness for each scanning line in the first driving method. The case where there are six scanning lines is shown, and the display brightness is shown in shades. As shown in FIG. 2, the first field is formed by sequentially performing scanning from the top and performing positive writing four times. Then, the data signal voltage is inverted, and scanning is sequentially performed from the top to perform negative writing four times, and the second field ends. One frame is formed by these first field and second field. The time of the first field is 16.7 ms. The luminance becomes brighter as the number of writing times increases in the same field, as shown by the transmittance in FIG.
The writing time of each scan line is n within one field.
When writing is performed once, the writing time is 1 / n of the normal driving method.

Embodiment 2 This embodiment is another example of the embodiment of the second driving method of the liquid crystal display element according to the present invention, and FIG. 3A is a waveform diagram of the voltage applied to the data line. 3 (b) is a waveform diagram of the voltage applied to the gate line, and FIG.
It is a figure which shows the transmittance | permeability change at the time of applying the voltage of (a) and (b). The present embodiment example corresponds to the one in which the frequency of AC driving is increased. Specifically, the voltage applied to the data line in FIG. 3A is several times that in FIG. 12 (twice in this figure).
It is a square wave with a frequency of. On the other hand, the voltage applied to the gate line in FIG. 3B is turned on once during one field period.
There is a pulse, and each field is given for each voltage code in FIG. As a result, in FIG. 3, there are four fields in one frame. In the present embodiment example, FIG.
As shown in (c) the change in transmittance, a step response occurs in response to the writing signal within the period of 16.7 ms, the vibration width is gradually suppressed, and the stable state is reached by the fourth writing.

FIG. 4 is a diagram showing a time chart for each scanning line and a display brightness for each scanning line. The case where there are 6 scanning lines is shown, and the display brightness is shown in shades. As shown in FIG. 4, the first field is formed by sequentially scanning from the top and performing positive writing, and then the second field is formed by inverting the data signal voltage and sequentially scanning from the top and performing negative writing. To be done. Further, the third field is formed by sequentially scanning from the top and performing positive writing, and then the fourth field is formed by inverting the data signal voltage and sequentially scanning from the top and performing negative writing. One frame is formed by these first to fourth fields. The time of the first field is 8.35 ms. The brightness oscillates within the frame and stabilizes at the end of the frame as shown in the transmittance graph of FIG. The writing time of each scan line is 1 / n of the writing time of the normal AC driving method when AC driving is performed n times in one frame.

Embodiment 3 This embodiment is an example of an embodiment of a third driving method of a liquid crystal display element according to the present invention, and FIG. 5 shows a time chart for each scanning line and a display luminance for each scanning line. FIG. In the present embodiment, the same data signal is written a plurality of times within one field, as in the first embodiment. The difference from the first embodiment is the scanning method. In this embodiment example,
Scan multiple scan lines simultaneously. As shown in FIG. 5, the scan line group is divided into an upper block and a lower block,
One line of each of the upper block and the lower block is selected and sequentially scanned from top to bottom. As a result, it is possible to secure twice as long as the time required for writing the individual scanning lines as compared with the first embodiment. The writing time for each scanning line is 1
When writing is performed n times in the field and divided into m scanning line blocks, the writing time of the normal AC driving method becomes m / n.

Embodiment 4 This embodiment is an example of an embodiment of a fourth driving method of a liquid crystal display element according to the present invention, and FIG. 6 shows a time chart for each scanning line and a display brightness for each scanning line. FIG. In the present embodiment example, as in the second embodiment example, AC driving is performed a plurality of times within one frame. The difference from the second embodiment is the scanning method. In this embodiment, a plurality of scan lines are simultaneously scanned. As shown in FIG. 6, the scanning line group is divided into an upper block and a lower block, and one line of each of the upper block and the lower block is selected and sequentially scanned from top to bottom. As a result, it is possible to secure twice as much time as writing in each scanning line as compared with the second embodiment. still,
The writing time of each scan line is A times n times in one frame.
When C drive is performed and divided into m scanning line blocks,
It is m / n of the writing time of the normal AC driving method.

Embodiment 5 This embodiment is an example of an embodiment of the fifth driving method of the liquid crystal display device according to the present invention, and FIG. 7 shows the time distribution of the brightness of the light source and the time distribution for each scanning line. It is a figure which shows the time chart which shows a structure and operation | movement, and the display brightness for every scanning line. In this embodiment, the same data signal is written a plurality of times in one field, as in Embodiment 1, and Embodiment 3
The same scanning is performed. The difference from the first and third embodiments is that the field sequential driving is performed, and each field has a constant display period 105. FIG. 7 shows an example with 12 scanning lines.

One frame is divided into three fields corresponding to each color, and AC driving is performed in each field. In addition, writing is performed a plurality of times within each polarity of AC driving. On the other hand, the scan line is also divided into multiple blocks,
At the same time, writing is performed. As shown in FIG. 7, the scanning line is divided into four blocks, the scanning line at the top of each block is simultaneously selected and written, and writing is sequentially performed from top to bottom. The scanning is repeated four times to continuously write one polarity (here, positive) of AC driving. After that, the display period 105 is given. The polarity of the signal data is inverted, and similarly, scanning four blocks simultaneously is repeated four times,
The negative writing 103 is completed and the display period 105 is given. At this time, the light source is turned on in the range including the display period and turned off in the range where the transmittance is unstable. By this procedure, the first field is formed, and the display of red ends. Similarly, the fields of green and blue are displayed, and one frame is formed by three fields.

Embodiment 6 This embodiment is an example of an embodiment of a sixth driving method of a liquid crystal display device according to the present invention, and FIG. 8 shows a configuration of time distribution of luminance of a light source and time distribution for each scanning line. FIG. 3 is a diagram showing a time chart showing the operation and display brightness for each scanning line. In the present embodiment, as in the second embodiment, AC driving is performed a plurality of times within one field, and the same scanning as in the fourth embodiment is performed. The difference from the second and fourth embodiments is that the field sequential driving is performed, and that each field has a constant display period 105. FIG. 8 shows an example with 12 scanning lines. One frame is divided into three fields corresponding to each color, and AC driving is performed in each field.
Further, AC driving is performed multiple times. On the other hand, the scanning line is also divided into a plurality of blocks and writing is performed at the same time. Figure 8
As shown in, the scanning line is divided into four blocks, and the scanning line at the top of each block is simultaneously selected and written, and writing is sequentially performed from top to bottom. The scanning is repeated four times to perform AC driving for two cycles. After that, the display period 105 is given. At this time, the light source is turned on in the range including the display period and turned off in the range where the transmittance is unstable. By this procedure, the first field is formed, and the display of red ends. Similarly, the fields of green and blue are displayed, and one frame is formed by three fields.

[0028]Embodiment 7 The present embodiment is an example of the embodiment of the liquid crystal display device according to the present invention.
As an example, the driving methods of the first to fourth embodiments
It is a liquid crystal display device using a shift. FIG. 9 shows the drive of the present invention.
Schematic showing an example of the configuration of a liquid crystal display device to which the moving method is applied
It is a figure. The liquid crystal display device of the present embodiment has two supports.
An electrode 7 is formed on each of the substrates 6 and a liquid crystal is formed thereon.
An alignment film 8 for aligning is formed. This pair of support substrates
Liquid crystal 9 is sandwiched between 6 and a pair of polarizing plates5Support substrate
Provided on the outside of 6. With this configuration, a liquid crystal display device is usually used.
Is configured. The operation of this embodiment will be described in detail below.
explain. Each drain bus line should be
The signal data waveform corresponding to the driving method is displayed on each gate line.
Is applied corresponding to. On the other hand, for each gate bus line
Will turn on the active device when the line is selected
The waveform shown in each of the embodiments is applied, and
The waveform of the drain line is applied to the liquid crystal by the display electrode.
It Until the gate line is selected again, power is supplied to the liquid crystal section.
The pressure is retained. As a result, the liquid crystal has no memory
However, the display holding operation is possible. Reset is
Apply predetermined signal data for reset inline,
Moreover, the waveform that turns on the switch of the active element is
It is applied at the timing shown in the embodiment. With the above configuration
Therefore, the driving method according to any one of Embodiments 1 to 4 is applied.
The liquid crystal display device is realized.

Embodiment 8 This embodiment is an example of an embodiment of a liquid crystal display device according to the present invention, which is a liquid crystal display device using the driving method of Embodiment 5 or 6. In the liquid crystal display device of the present embodiment example, an electrode is formed on each of two support substrates, and an alignment film for aligning liquid crystals is formed on the electrode. Liquid crystal is sandwiched between the pair of support substrates, and a pair of polarizing plates is provided outside the support substrates. Further, a light source for field sequential display is provided on one polarizing plate side. With this configuration, a liquid crystal display device to which any one of the driving methods of the fifth and sixth embodiments is applied is realized.

[0030]

The present invention will be described in detail below with reference to examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. Example 1 This example is one example of the liquid crystal display device according to the present invention. In this embodiment, there are 480 gate bus lines and 6 gate bus lines.
Chromium (Cr) wires with a line width of 10 μm formed by sputtering were used for the 40 drain bus lines, and silicon nitride (SiNx) was used for the gate insulating film. The size of one unit pixel is 330 μm in height and 110 μm in width,
A TFT (thin film transistor) was formed using amorphous silicon, and a pixel electrode was formed by a sputtering method using indium tin oxide (ITO) which is a transparent electrode. The glass substrate on which the TFTs were thus formed in an array was used as the first substrate.

On the second substrate facing the first substrate, after forming a light shielding film using chromium, a transparent electrode (common electrode) using ITO is formed, and a color filter is dyed by a dyeing method. It was formed in a matrix, and a protective layer using silica was provided on the upper surface thereof. Then, the soluble polyimide was printed by a printing method and baked at 180 ° C. to remove the solvent. Polyamic acid was applied onto this polyimide film by spin coating and baked at 200 ° C. for imidization to form a polyimide film. A buff cloth using nylon is wrapped around a roller with a diameter of 50 mm, the rotation speed of the roller is 600 rpm, and the stage moving speed is 40 mm /
Second, push amount 0.7 mm, rubbing 2 times 10 °
The polyimide film was rubbed in a direction that would result in cross rubbing. The thickness of the alignment film measured by the contact step meter was about 500Å, and the pretilt angle measured by the crystal rotation method was 1.5 degrees.

Approximately 2 pieces are formed on one of the pair of glass substrates.
Disperse micropearls, which are spherical spacers with a diameter of μm, and
On the other hand, a cylindrical glass rod spacer with a diameter of about 2 μm
A thermosetting sealing material having dispersed therein was applied. these
Substrate rubbing the substrate crossed by 10 °
So that both substrates face each other so that
Assemble the panel with a gap of 2 μm by curing the sealing material.
I was Between the panels, page 61 of Asia Display 95
To induce V-shaped switching shown on pages 64 to 64
The electrically conductive liquid crystal composition was prepared by applying an isotropic phase (I
So). Triangulate the spontaneous polarization value of this liquid crystal
165 nC / cm when measured by applying a wave ²And
It was. Also, the response speed varied depending on the gradation voltage,
It was between 200 and 800 microseconds.
Using the arbitrary waveform generator and high-power amplifier at 85 ℃
A rectangle with a frequency of 3 kHz and an amplitude of ± 10 V on the entire panel.
0.1 ° C / room temperature up to room temperature while applying a wave and an electric field
It was gradually cooled at a rate of min. Liquid crystal produced in this way
A driver IC for driving is attached to the panel,
I set it up.

In this liquid crystal display device, the driving method of the first embodiment is applied. Specifically, 1 field period is 1
6.7 milliseconds, one frame period is 33.4 milliseconds, the writing time of each scanning line is 4.2 microseconds, and writing is performed eight times in one field. FIG. 10 shows applied waveforms and changes in transmittance measured for one pixel. Figure 10
10A shows the drain applied voltage, FIG. 10B shows the gate applied voltage, and FIG. 10C shows the transmittance change. In this embodiment, since the spontaneous polarization value of the liquid crystal is large, the change in the retention rate due to the response of the liquid crystal after writing is large. As a result, the number of times of writing necessary for the transmittance to be in a stable state was 8 times, which was larger than that of the first embodiment. According to this method, a liquid crystal display device which makes use of the high-speed response in which all halftone responses are completed within one field can be obtained without providing a frame memory regardless of the reset pulse method.

Embodiment 2 This embodiment is another embodiment of the liquid crystal display device according to the present invention. In this example, a TFT substrate and a CF (color filter) substrate were manufactured in the same manner as in Example 1, and in the same manner as in Example 1, steps up to panel assembly were performed. The liquid crystal composition disclosed in Japanese Patent Application No. 9-093853 was injected into this panel in an isotropic phase (Iso) state at 85 ° C. in a vacuum. The composition ratio was adjusted so that the spontaneous polarization value of this liquid crystal composition was about 20 nC / cm ² , and a triangular wave was applied to make an actual measurement.
It was nC / cm ² . The response speed was between 600 microseconds and 2 milliseconds, although it varied depending on the gradation voltage. After the injection, the mixture was gradually cooled to room temperature at a rate of 0.1 ° C / min. A driver IC for driving was attached to the liquid crystal panel manufactured in this way to obtain a liquid crystal display device.

This liquid crystal display device was driven by the driving method of the first embodiment. Specifically, one field period is 16.
7 milliseconds, 1 frame period was 33.4 milliseconds, the writing time of each scanning line was 11.5 microseconds, and writing was performed three times in one field. FIG. 11 shows applied waveforms and changes in transmittance measured for one pixel. Figure 11
11A shows the drain applied voltage, FIG. 11B shows the gate applied voltage, and FIG. 11C shows the transmittance change. In this example, since the spontaneous polarization value of the liquid crystal was small, the change in the retention rate due to the liquid crystal response after writing was small. As a result, the number of times of writing required for the transmittance to be in a stable state was 3 times, which is smaller than that of the second embodiment. By reducing the number of times of writing required in this way, the reduction of the writing time can be suppressed as compared with the first embodiment. At the same time, the increase in the frequency of the drive circuit was suppressed and the cost of the drive circuit was reduced. It should be noted that, although the response speed of the liquid crystal itself is slower than that of the first embodiment, the time required to reach a stable state was faster than that of the first embodiment when used in this driving method. is there. As in the first embodiment, the present method can provide a liquid crystal display device which utilizes the high-speed response in which all halftone responses are completed within one field without providing a frame memory regardless of the reset pulse method. It was

Embodiment 3 This embodiment is still another embodiment of the liquid crystal display device according to the present invention. In this embodiment, the TFT is similar to the first embodiment.
A substrate was produced. On the second substrate facing the TFT substrate, after forming a light-shielding film using chromium, a color filter is formed by an ink jet method using a bubble jet using a dye, and then ITO is formed on the second substrate. A protective layer was provided. A buff cloth made of rayon is wrapped around a roller having a diameter of 50 mm, and the polyimide film is oriented in a direction such that the number of rotations of the roller is 600 rpm, the stage moving speed is 40 mm / sec, the pushing amount is 0.7 mm, and the rubbing is performed twice for parallel rubbing. Was rubbed. The thickness of the alignment film measured by a contact step meter is about 500Å
And the pretilt angle measured by the crystal rotation method was 7 degrees. Such a pair of glass substrates, one of which is a spherical spacer having a diameter of about 9.5 μm, is scattered on the other side, and the other of which is a columnar glass rod spacer having a diameter of about 9.5 μm is dispersed. A sealing material was applied. These substrates were arranged so that the rubbing treatment directions were parallel to each other so that the substrates were opposed to each other, and the sealing material was cured by a treatment of irradiating ultraviolet rays in a non-contact manner to assemble a panel having a gap of 9.5 μm. A nematic liquid crystal was injected into this panel. In this embodiment, the S.I.
OCB (Optical Compensated) shown on pages 927 to 930 of Dee 94 Digest
A birefringence display mode was added with a compensator. A driver for driving was attached to the liquid crystal panel manufactured in this way to obtain a liquid crystal display device. Although the response speed of the liquid crystal mode itself varied depending on the gradation voltage,
It was between 1.5 and 4 ms.

This liquid crystal display device was driven by the driving method of the first embodiment. Specifically, 1 field period is 1
6.7 milliseconds, one frame period is 33.4 milliseconds, the writing time of each scanning line is 11.5 microseconds, and writing is performed three times in one field. The applied waveform is shown in Figure 1.
It was similar to 1. Since the response speed of the liquid crystal itself is slower than that of the second embodiment, the response of the transmittance is slightly slower. However, since the number of writings to reach the stable state is small, the time required to reach the stable state is faster than that in the first embodiment, which has a response speed about 5 times faster. As in the first and second embodiments, the present method makes use of the high-speed response in which all halftone responses are completed within one field without providing a frame memory regardless of the reset pulse method. was gotten.

Embodiment 4 This embodiment is still another embodiment of the liquid crystal display device according to the present invention. In this example, a liquid crystal panel was manufactured in the same manner as in Example 2, and a driver for driving was attached to obtain a liquid crystal display device. The driving method of the present liquid crystal display device is the driving method of the second embodiment. In this embodiment, the write time per write could be longer than that in the second embodiment.

Embodiment 5 This embodiment is still another embodiment of the liquid crystal display device according to the present invention. In this example, a liquid crystal panel was manufactured in the same manner as in Example 2, and a driver for driving was attached to obtain a liquid crystal display device. The driving method of the present liquid crystal display device is the driving method of the fourth embodiment. In this embodiment, the write time per write can be made longer than that in the fourth embodiment, which is not different from the normal AC drive. As a result, it is possible to realize a high-performance liquid crystal display device at low cost without the need to use a high frequency element.

Embodiment 6 This embodiment is still another embodiment of the liquid crystal display device according to the present invention. The liquid crystal panel of the present embodiment has the same configuration as the liquid crystal panel of the second embodiment. A drive driver and a backlight capable of high-speed switching are used for this liquid crystal panel to provide a field sequential liquid crystal display device. In this liquid crystal display device, the driving method and the scanning of the luminance of the light source are the same as those in the fifth embodiment.
Specifically, the number of times of writing with one polarity was 4, and the scanning line was divided into two blocks. The display period 105 was set to 2 milliseconds, the writing time of each scanning line was set to 3.5 microseconds, and the one frame period was set to 33.3 milliseconds. At this time,
The lighting time of the light source is 2.5 for each color within one frame.
It was possible to secure 2 milliseconds, that is, 5 milliseconds.

Embodiment 7 This embodiment is still another embodiment of the liquid crystal display device according to the present invention. The configuration of the liquid crystal panel of the present embodiment is the same as the configuration of the liquid crystal panel of the second embodiment. A drive driver and a backlight capable of high-speed switching are used for this liquid crystal panel to provide a field sequential liquid crystal display device. In this liquid crystal display device, the driving method and the scanning of the luminance of the light source are the same as those in the sixth embodiment.
Specifically, AC drive was performed twice within one frame, and the scanning line was divided into two blocks. The display period 105 was set to 7.7 milliseconds, the writing time of each scanning line was set to 3.5 microseconds, and one frame period was set to 33.3 milliseconds.
At this time, the lighting time of the light source was secured to be 2.5 ms twice for each color within one frame, that is, 8 ms, which was longer than that of the sixth embodiment.

Embodiment 8 This embodiment is still another embodiment of the liquid crystal display device according to the present invention. In this example, a microdisplay was manufactured and a reflective projector was manufactured. Advanced ·
It was produced in the same manner as the microdisplay by Display Tech Co. as shown at the beginning of the January 1997 issue of Imaging Magazine. Specifically, M on a silicon wafer
A DRAM was manufactured by forming the OS-FET according to the 0.8 μm rule. The size is 1 / die size
2 inches, pixel pitch of about 10 μm, 1 mega-DRA
M was formed. The pixel aperture ratio was 90% or more. In addition, the formed DRAM surface has chemical mechanical
It was flattened by applying a polishing technique. on the other hand,
A cover glass for microscope observation was used as the opposing substrate. A portion including a drive circuit was cut out from a silicon wafer, an alignment film made of soluble polyimide was printed, and baked at 170 ° C. to remove the solvent. A buff cloth using nylon is wrapped around a roller having a diameter of 50 mm, the rotation speed of the roller is 600 rpm, the stage moving speed is 40 mm / sec,
The polyimide film was rubbed with a pushing amount of 0.7 mm and a rubbing frequency of 2 times. The thickness of the alignment film measured by the contact step meter was about 500Å, and the pretilt angle measured by the crystal rotation method was 1.5 degrees.

Further, a photo-curable sealing material in which a cylindrical glass rod spacer having a diameter of about 2 μm was dispersed was applied. These substrates are placed facing each other, and the sealing material is cured by non-contact ultraviolet ray treatment to form a gap of 2 μm.
m panels were assembled. The V-shaped antiferroelectric liquid crystal composition shown in pages 61 to 64 of Asian Display 95 was injected into this panel in a vacuum at 85 ° C. in an isotropic phase (Iso) state. 85 ° C
Using an arbitrary waveform generator and high-power amplifier, apply a rectangular wave with a frequency of 3 kHz and an amplitude of ± 10 V to the entire panel surface, and apply an electric field to reach room temperature at 0.1 ° C / min.
It was annealed at the speed of. Further, a reflective field sequential projector was manufactured using a three-color light emitting diode, a collimator lens for obtaining parallel light, a polarization conversion element, a projection lens, and the like. The driving method of this liquid crystal display device was the driving method of the sixth embodiment. As a result of this method, a fast responsive projector display was obtained.

[0044]

According to the present invention, in a high-speed response liquid crystal display device, a reset pulse is not used, calculation between image data is not performed, high contrast and high brightness, and electrical asymmetry are obtained. It is possible to realize a method of driving a liquid crystal display element that is not affected by the above. According to the present invention, a liquid crystal display device using those driving methods, and
A field sequential liquid crystal display device can be realized.

[Brief description of drawings]

FIG. 1 is a waveform diagram illustrating a configuration and an operation of a first embodiment, FIG. 1A is a waveform diagram of a voltage applied to a data line, and FIG.
1B is a waveform diagram of a gate line applied voltage, and FIG. 1C is a diagram showing a change in transmittance when the voltages of FIGS. 1A and 1B are applied to a fast response liquid crystal.

FIG. 2 is a diagram showing a time chart for each scanning line and a display luminance for each scanning line.

3A and 3B are waveform diagrams illustrating the configuration and operation of the second embodiment, and FIG. 3A is a waveform diagram of a data line applied voltage.
3B is a waveform diagram of the voltage applied to the gate line, and FIG. 3C is a diagram showing a change in transmittance when the voltages of FIGS. 3A and 3B are applied to the fast response liquid crystal.

FIG. 4 is a diagram showing a time chart for each scanning line and a display luminance for each scanning line.

5A and 5B are diagrams illustrating the configuration and operation of the third embodiment, showing a time chart for each scanning line and a display luminance for each scanning line.

6A and 6B are diagrams illustrating a configuration and an operation of a fourth embodiment, and are a time chart for each scanning line and a display luminance for each scanning line.

FIG. 7 is a diagram showing the configuration and operation of Example 5;
It is a time chart for each light source brightness and scanning line.

FIG. 8 is a diagram showing a configuration and an operation of a sixth embodiment,
It is a time chart for each light source brightness and scanning line.

FIG. 9 is a cross-sectional view showing the layer structure of the liquid crystal display device of Example 7.

10 is a diagram showing an operation of the liquid crystal display device of Example 1, FIG. 10 (a) is a waveform diagram of a data line applied voltage, FIG.
10B is a waveform diagram of the voltage applied to the gate line, and FIG. 10C is a diagram showing a change in transmittance when the voltages of FIGS. 10A and 10B are applied.

11 is a diagram showing an operation of the liquid crystal display device of Example 2, FIG. 11 (a) is a waveform diagram of a voltage applied to a data line, FIG.
(B) Waveform diagram of gate line applied voltage, FIG.
It is a figure which shows the transmittance | permeability change at the time of applying the voltage of 1 (a), (b).

12A and 12B are diagrams illustrating a data signal waveform by a conventional AC driving method, FIG. 12A is a waveform diagram of a data line applied voltage, FIG. 12B is a waveform diagram of a gate line applied voltage, and FIG.
FIG. 12C is a diagram showing changes in transmittance when the voltages of FIGS. 12A and 12B are applied to the fast response liquid crystal.

13 is a diagram showing a time chart for each scanning line and a display luminance for each scanning line in the conventional AC driving method of FIG.

FIG. 14 is a diagram showing a change with time in luminance when a reset method drive is applied to a conventional OCB mode.

15A and 15B are diagrams illustrating a data signal waveform by a conventional pseudo DC driving method, FIG. 15A is a waveform diagram of a data line applied voltage, and FIG. 15B is a waveform diagram of a gate line applied voltage. 1
FIG. 5C is a diagram showing a change in transmittance when the voltages of FIGS. 15A and 15B are applied to the fast response liquid crystal.

16 is a diagram showing a time chart for each scanning line and a display luminance for each scanning line in the conventional pseudo DC driving method of FIG.

[Explanation of symbols]

5 Polarizer 6 substrate 7 electrodes 8 Alignment film 9 LCD 101 Positive writing 102 Positive display 103 negative writing 104 negative display 105 Display period

Continuation of front page (56) Reference JP-A-7-199149 (JP, A) JP-A-8-234161 (JP, A) JP-A-6-222360 (JP, A) JP-A-9-90909 (JP , A) JP-A-9-304794 (JP, A) JP-A-6-236166 (JP, A) JP-A-7-64055 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB) Name) G02F 1/133 G09G 3/36

Claims (8)

(57) [Claims] 1. A response speed faster than one frame time
In a liquid crystal display element, a gate pulse is applied a plurality of times within one frame, and a signal voltage with the same amplitude and polarity inverted a plurality of times at a predetermined cycle is applied for each gate pulse A
A method for driving a liquid crystal display element, which is characterized in that data is written by C drive. 2. A scan line group is divided into a plurality of blocks,
The method for driving a liquid crystal display device according to claim 1, wherein a plurality of blocks are simultaneously scanned. 3. One frame has three colors corresponding to three colors.
A driving method of a field sequential liquid crystal display device, which is divided into one field and data is sequentially displayed in each field, wherein the driving method of each color is the driving method of the liquid crystal display element according to claim 2. Driving method for liquid crystal display device. 4. The method for driving a liquid crystal display element according to claim 3, wherein there is a period during which the light source is not turned on until the display image is stabilized . 5. A liquid crystal display device, characterized in that the liquid crystal display device constituting the liquid crystal display device is driven by the method for driving a liquid crystal display device according to claim 1. 6. A field-sequential liquid crystal display device in which information of three colors is sequentially displayed in one frame,
A field-sequential color liquid crystal display device, which is driven by the method for driving a liquid crystal display device according to claim 3. 7. The liquid crystal display method is OCB method or V
7. A display method using an antiferroelectric liquid crystal exhibiting a V-shaped voltage-transmittance characteristic is used.
The liquid crystal display device according to item 1. 8. The liquid crystal display device according to claim 5, wherein a thin film transistor or a switching element on a silicon substrate is used.