JPH1124043A - Liquid crystal display device and its driving method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an excellent display without flickering by changing a scanning frequency and/or a scanning order according to a temperature distribution of liquid crystal display elements. SOLUTION: A plurality of temperature detection elements 136 are attached to display elements 131 in the scanning direction (vertical direction), and temperature information are taken therefrom into a micro processor unit(MPU) of a panel controller 134. MPU splits the scanning lines of the display elements 131 into a plurality of blocks based on the temperature information taken in, and assigns weights to each scanning lock according to temperature differences. A scanning frequency is changed according to detected temperatures for each scanning block. Namely, a scanning order is changed for whole screen. A scanning frequency of picture elements in a low threshold value part of the cell, namely, a scanning frequency of higher temperature picture elements is made higher than that of a lower threshold value, and a frame frequency of picture elements in the lower threshold value part of the cell is made higher, and thus, the screen is prevented from flickering.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a ferroelectric liquid crystal (F).
LC) and a driving method thereof using a liquid crystal display (LC).
In particular, the present invention relates to a liquid crystal display device that performs gradation display by a matrix driving method and a driving method thereof.

[0002]

2. Description of the Related Art A display device using a ferroelectric liquid crystal is disclosed in Japanese Patent Application Laid-Open No. 61-94023. 1 to 3 μm so that the transparent electrode is on the inner surface.
It is well known that a ferroelectric liquid crystal is injected into a liquid crystal cell having a cell gap of about μm.

A ferroelectric liquid crystal element has two stable states, a light transmitting state and a blocking state, and is mainly used as a binary (white / black) display element. However, a multi-valued display, that is, a halftone display is also possible. . Japanese Patent Application Laid-Open No. 4-218 as a halftone display method
As disclosed in Japanese Unexamined Patent Publication No. 022 and No. 5-158444, an area gray scale method has been proposed in which an intermediate light transmission state is formed by controlling an area ratio of a bistable state in a pixel. I have. Hereinafter, this method will be described.

FIG. 9 is a diagram schematically showing the relationship between the switching pulse amplitude and the light transmittance in a ferroelectric liquid crystal element, and a cell (element) which is initially in a completely light-blocked (black) state.
7 is a graph in which the amount of transmitted light I after applying a one-shot pulse of one polarity is plotted as a coefficient of the amplitude V of the one-shot pulse. When the pulse amplitude V is equal to or smaller than the threshold value Vth (V ≦ Vth), all the pixels remain in the light blocking state, so that the amount of transmitted light does not change, and the transmitting state after pulse application is as shown in FIG. This is the same as the state of FIG. 10A showing the state before application. The pulse amplitude V exceeds the threshold value Vth (Vth <V <V
sat) and a part of the pixel is in the other stable state, that is, FIG.
The state transits to the light transmission state shown in (c) and shows an intermediate amount of transmitted light as a whole. When the pulse amplitude further increases and the pulse amplitude V becomes equal to or higher than the saturation value Vsat (Vsat ≦ V), as shown in FIG. 10D, all the pixels are in a light transmitting state, and the light amount reaches a constant value. That is, in the area gradation method, halftone display is realized by controlling the voltage so that the pulse amplitude V becomes (Vth <V <Vsat).

However, the relationship between the amplitude V of a single pulse and the amount of transmitted light I shown in FIG. 9 depends on the cell gap, temperature, and the like. That is, if there is a cell gap distribution or a temperature distribution in the cell, different grayscale levels are displayed for applied pulses having the same pulse amplitude. FIG. 11 is a graph for explaining this, and is a graph showing the relationship between the pulse amplitude V and the amount of transmitted light I as in FIG. 9, but showing the relationship between the two at different temperatures, that is, the relationship at a high temperature. And a curve L indicating a relationship at a low temperature. In general, it is not unusual for a display having a large display size to generate a temperature distribution in the same cell. Therefore, even if an attempt is made to display a halftone with a certain driving voltage Vop, as shown in FIG. In some cases, the halftone level in the same cell varies, making it impossible to obtain a uniform gradation display.

A driving method (hereinafter referred to as a four-pulse method) that solves the above-mentioned problem has been proposed in Japanese Patent Application Laid-Open No. Hei 4-218022. In the four-pulse method, the same amount of transmitted light is obtained by applying a plurality of pulses to all of a plurality of pixels which are on the same scanning line as one cell and have different thresholds due to the influence of temperature distribution and the like. Is to get.

Specifically, the following series of write operations are performed. FIG. 12 is a diagram showing a driving waveform of the four-pulse method, FIG. 13 is a diagram for explaining driving means of the four-pulse method, and FIG.
FIG. 4 illustrates a display state when the four-pulse method is used. The pulses (A) to (D) shown below are all scanning waveforms. First, the entire surface of the cell is written to a certain state Q0 by the reset pulse (A) (entire reset). The reset pulse (A) is a waveform having a sufficient energy for a composite voltage of the scanning waveform and the information waveform to reset the entire surface, no matter what information waveform comes. Second, a pulse (B) having a polarity opposite to that of the pulse (A) is applied. A voltage obtained by combining the pulse (B) and the information waveform is applied to the pixel, the pixel in the high threshold portion of the cell is written until the light transmittance of Ia% is reached, and the pixel in the low threshold portion of the cell is completely written. Inverted Q10
It becomes a state of 0. Assuming that the light transmittance in the state of Q0 is 0%, Q1 is 100% and that of Qa is Ia%. Third, a pulse (C) having a polarity opposite to that of the pulse (B) is applied.
The information waveform at this time is 0V. Then, no switching occurs in the pixels in the high threshold portion of the cell, and the state Qa created by the pulse (B) is stored. On the other hand, the state of Q100 (light transmittance of 100%) is changed from the state of Q100 (light transmittance of 100%) to the state Qb of light transmittance (100-Ib)% in the pixel at the low threshold value portion of the cell. Fourth, a pulse (D) having a polarity opposite to that of the pulse (C) is applied. A voltage obtained by combining the pulse (D) and the information waveform is applied to the pixel, and the pixel in the high threshold portion of the cell stores the state Qa created by the pulse (B), and the pixel in the low threshold portion of the cell The state changes to the state Qc with a light transmittance of (100−Ib + Ic)%. The information waveform at this time is a pulse (B)
Has the same shape as the information waveform synthesized. Thus, finally, the pixels in the high threshold portion and the pixels in the low threshold portion of the cell realize the same light transmittance state Qa. FIG. 13 shows that the transmittance Ia% and the transmittance (100−Ib + Ic)% are the same.
It is clear from the fact that the triangle abc and the triangle a'b'c 'in the middle are congruent.

Further, Japanese Patent Application Laid-Open No. Hei 5-158444 proposes a pixel shift method in which the writing time is shorter than the four-pulse method. In the pixel shift method, by inputting and selecting different scanning signals to a plurality of scanning signal lines at the same time, a distribution of the electric field intensity over the plurality of scanning lines is created, and gradation display is performed. The outline of the pixel shift method will be described below.

The liquid crystal cell used has a threshold distribution in one pixel as shown in FIG. In the figure, 81 is glass, 82 is liquid crystal, 83 is an information side electrode, 84 is a scanning side electrode, 85 is a base layer, and 86 is an alignment film. FIG. 16A is a diagram schematically illustrating the relationship between the switching pulse amplitude and the light transmittance when pixels on two scanning lines are grouped together. Here, characteristics at three temperatures T1, T2, and T3 existing in the panel surface are shown by three lines, respectively. Note that the cause of the threshold value variation is other than the temperature change, but here, for convenience of explanation, the description will be made mainly using the temperature change.

In FIG. 16A, the transmittance is 0% to 100%.
Is the display area of the pixel B on the scanning line 2, and the transmittance is 100%.
〜200% is represented as a display area of the pixel A on the scanning line 1. Since one pixel is constituted per one scanning line, when two pixels are simultaneously scanned, the transmittance when both the pixel A and the pixel B are all in the light transmitting state is set to 200 for convenience.
%. In the pixel shift method, two scanning lines are simultaneously selected for one piece of gradation information, but one gradation information is displayed in a region having an area of one pixel.

In FIG. 16, at the temperature T1, the input gradation information is 0% when the applied voltage is V0, and 10% when the applied voltage is V100.
It is written in the range corresponding to 0%. As can be seen from the figure, at the temperature T1, this gradation control range (pixel region) is entirely on the scanning line 2. However, when the temperature changes from T1 to T2
When the same voltage is applied to the pixel, the region higher than the temperature T1 in the pixel is inverted. To correct this, the temperature T2
Is set so as to extend over the scanning line 1 and the scanning line 2. When the temperature further rises to T3,
The image area to be drawn by changing the applied voltage from V0 to V100 is set only on the scanning line 1.

In this manner, by displaying the pixel area for performing the gradation display by the temperature on the two scanning lines while shifting, the gradation display can be correctly performed in the temperature range from T1 to T3. Pixel A having the same voltage-transmittance characteristic
In order to cause the pixel A to display 100 to 200% using the pixels A and B, for example, the amplitude of the selection pulse of the pixel A (corresponding to the pulse (D) of the four-pulse method) is set to (Corresponding to B)) is set to be smaller by Vsat-Vth than the amplitude of (B). In the pixel shift method, 4
Since the pulses corresponding to the pulses (D) and (B) of the pulse method can be applied to the pixels A and B at the same timing, the writing time can be reduced compared to the four-pulse method.

[0013]

However, when the above-described gradation driving method such as the four-pulse method or the pixel shift method is used, the following drawbacks may occur. That is, in order to realize the above-mentioned gradation driving method, it is necessary to perform writing by the next pulse after the optical response of the liquid crystal by each writing is sufficiently settled. Here, the time until the optical response of the liquid crystal sufficiently falls is called a relaxation time. The relaxation time will be described below.

FIGS. 17 and 18 are graphs showing the relaxation time. FIG. 17 shows a change in the amount of transmitted light when a single pulse is applied. As shown in FIG. 17, it takes about 200 μsec to settle down to a certain light amount level after the application of the write pulse. FIG. 18 shows a change in the final transmitted light amount when another pulse (crosstalk pulse) is applied after the application of the write pulse. The crosstalk pulse is a bipolar pulse of ± Vc, the pulse width of each polarity is the same as the write pulse width, and the pulse amplitude | ± Vc | is a value sufficiently smaller than the inversion threshold Vth. The final transmitted light amount depends on the idle period T between the write pulse and the crosstalk pulse, and the idle period T
Is greater than or equal to 200 μsec, the final transmitted light quantity is substantially unaffected by the subsequent crosstalk pulse. This also indicates that the relaxation time is about 200 μsec. In particular, after writing by the pulse (B), the state Qx
The appearance of (light transmittance Ix%) for a period of 200 μsec is largely related to the phenomenon of flicker, which will be described later, which lowers the display quality.

In a scanning type display element, there is a phenomenon called flicker caused by a periodic luminance change that occurs during repeated scanning for forming an image. Flicker is caused by the frame frequency f (reciprocal of the time required to rewrite one screen) or the field frequency F
It is also known to depend on. The field frequency is
It is defined as follows.

[0016]

(Equation 1) N in the above equation is the number of skips in the case of skip selective scanning. When it is necessary to perform line-sequential driving as in the pixel shift method, the display screen is divided into a plurality of scanning blocks, and each scanning block is driven in a line-sequential manner, and the scanning blocks are sequentially selected as a whole. This is the number of jumps (the number of scan blocks) when scanning. For example, N
The scanning line selection order when = 8 is 1, 9, 17, 2
5 .........

It is known that flicker is noticeable when a high luminance (white) period is present for a certain period or more when displaying a low luminance (black). FIG. 19 shows frame frequency f, field frequency F, and low luminance (black).
This shows the state of flicker occurrence when the period of high luminance (white) during display is used as a parameter. Observation of flicker was performed from a distance of 30 cm in front of the display element.

As shown in FIG. 19, the flicker depends on the frame frequency f and the field frequency F.
The longer the period of (white) is, the more likely it is to occur. In particular, flicker occurs when the length of the high luminance (white) period exceeds about 100 μsec to 200 μsec. For this reason, the phenomenon that the state Qx (light transmittance Ix%) appears for a period of 200 μsec after the above-described writing by the pulse (B) is sufficient to generate flicker when driven at a frame frequency of about 10 to 20 Hz. It will have a long length.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems in the prior art, and has as its object to provide a liquid crystal display device capable of performing good display without flicker and a driving method thereof.

[0020]

According to the present invention, there is provided a scanning electrode provided on each electrode substrate with a ferroelectric liquid crystal interposed between two electrode substrates disposed opposite to each other. A pixel is formed at the intersection of a group and an information electrode group, and when performing a gray scale display on a ferroelectric liquid crystal display element having a threshold distribution formed in each pixel, a scanning line is formed according to the temperature distribution of the liquid crystal display element. Is characterized by changing the scanning frequency and / or the scanning order.

In a preferred embodiment of the present invention,
The pixels (screen) of the liquid crystal display element are divided into at least two or more scanning blocks, and the scanning frequency is changed for each scanning block according to the detected temperature. That is, the scanning order is changed for the entire screen. The scanning frequency or the scanning order is determined by the microprocessor unit according to a table including the relationship between the temperature information, one horizontal scanning period, and the number of interlaced scans.

[0022]

The temperature is the most dominant factor that governs the threshold value of a liquid crystal cell (liquid crystal display element). The higher the temperature, the lower the threshold value. According to the above configuration, for example, in the driving of the FLC panel by the four-pulse method or the pixel shift method, the scanning frequency of the pixels in the low threshold portion of the cell, that is, the pixels having a high temperature, is made higher than the scanning frequency of the pixels in the high threshold portion of the cell, that is, the pixels having a low temperature. The flicker can be prevented by increasing the frame frequency of the pixel in the low threshold portion of the cell by increasing the frame frequency.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a block diagram of a display device according to an embodiment of the present invention, and FIG. 3 is a communication timing chart of image information. The graphic controller 135 transfers the scanning line address information and the image information for designating the scanning electrodes of the display element 131 to the panel controller 134. In this embodiment, since the scanning line address information and the image information are transferred on the same transmission line, the two types of information must be distinguished. The signal for this identification is AH / DL in FIG. 3, and when the AH / DL signal is at “H” level, PD0 to PD0
Indicating that the PD 15 is the scanning line address information,
The “L” level indicates that PD0 to PD15 are image information. The scanning line address information is converted into image information PD0 to PD15 by a panel controller 134 in the liquid crystal display device.
After being extracted from the image information transferred as the image data and decomposed into four scanning line address information of pulse (A) to pulse (D), the scanning line driving circuit is synchronized with the timing for driving the designated scanning line 133. This scanning line address information is transferred to decoders 1 to 4 in the scanning line driving circuit 133, and the designated scanning of the display panel 131 is performed via the decoders 1 to 4 according to the scanning waveform control information from the scanning waveform control circuit. Applied to the electrodes. on the other hand,
The image information is transferred to a shift register in the information line drive circuit 132, and is shifted by a transfer clock in units of 16 bits. When the shift register completes the shift of one scanning line in the horizontal direction, the data is transferred to the line memory in the information line driving circuit 132 and stored for one horizontal scanning period. Is applied to the information line electrode according to the information waveform control information.

In this embodiment, the driving of the display panel 131 and the graphic controller 1 in the liquid crystal display device are performed.
Since the generation of the scanning line address information and the image information in 35 is performed asynchronously, it is necessary to synchronize the devices when transferring the image information. The signal that governs this synchronization is shown in FIG.
The HSYNC is generated by the panel controller 134 in the liquid crystal display every one horizontal scanning period. The graphic controller 135 constantly monitors the HSYNC signal, and transfers the image information when the HSYNC signal is at the “L” level, and conversely transfers the image information for one horizontal scanning line when the HSYNC signal is at the “H” level. After completion, no transfer is performed.
That is, when the graphic controller 135 detects that the HSYNC signal in FIG. 3 has become “L” level, it immediately sets the AH / DL signal to “H” level and starts transferring image information for one horizontal scanning line. . The panel controller 134 in the liquid crystal display sets the HSYNC signal to the “H” level during the image information transfer period. After the writing to the display element 131 is completed after a predetermined one horizontal scanning period,
The panel controller 134 can receive the image information of the next scanning line by returning the HSYNC signal to the “L” level again. The graphic controller 135 has a frame memory, and the graphic controller can transfer image information for an arbitrary one scanning line.

The graphic controller 135 and the panel controller 134 are connected by a bidirectional communication line, and the display modes (SXGA, XGA,
VGA, etc.) to the panel controller 134
Can send information such as temperature information to the graphic controller 135.

By the way, in the ferroelectric liquid crystal, when a voltage higher than the threshold value Vth is applied, the liquid crystal molecules are switched to the first stable state, and this state is maintained until a voltage higher than -Vth in the opposite direction is applied. Has memory properties. Therefore, a certain scanning line is in a certain display state (state of a certain light transmittance).
, The display state once written is maintained without scanning the scanning line. That is, the cycle of scanning a certain scanning line can be extended to infinity when displaying the same image.

FIG. 4 is a diagram showing a driving waveform of the four-pulse method. In the case of the 4-pulse method, pulse (B) and pulse (D)
Since it is necessary to receive the gradation information of its own scanning line during one horizontal scanning period (1H), it takes substantially 2H time to scan one scanning line. In the ferroelectric liquid crystal of the present embodiment, it takes about 50 μsec for 1H. For example, when a display element of XGA (1024 information lines × 768 scanning lines) is considered, if all the scanning lines are sequentially scanned. It takes about 77 msec to scan the entire display element. This is approximately 1 when converted to the frame frequency.
It corresponds to 3 Hz.

Incidentally, a liquid crystal display element generally has a temperature distribution within a plane of the display element. Factors that cause this temperature distribution include heat generated by the backlight, heat generated by the drive circuit, and heat generated by the liquid crystal display element itself (charge / discharge energy for the electrostatic capacity of the display element is divided and consumed by a resistance portion such as a matrix electrode). Depending on the situation)
In particular, the heat generated by the liquid crystal display element itself depends on the state of the displayed image, that is, the display pattern.

FIG. 1 shows a processing flow of flicker prevention according to the first embodiment of the present invention. As shown in FIG. 2, a plurality of temperature detecting elements 136 are attached to the display element 131 in the scanning line direction (vertical direction), and the temperature information from this is sent to a microprocessor unit (MP) in the panel controller 134.
U). The MPU divides the scanning line of the display element 131 into a plurality of blocks (here, divided into five blocks) based on the acquired temperature information, and weights each scanning block according to the level of the temperature. Weighting is performed by the method described below.

As described above, in the four-pulse method (or the pixel shift method), when the same drive waveform is applied, the high threshold portion (the portion with a low temperature) is desired only with the pulse (A) and the pulse (B). However, in the low threshold part (the part where the temperature is high), the pulse reaches the desired luminance level after further passing through the pulse (C) and the pulse (D).

FIG. 5 is a diagram showing the transition of the amount of transmitted light between the high threshold portion and the low threshold portion when the black display screen is displayed (the flicker is most likely to occur in the black display screen). FIG. 6 shows the relationship between the temperature at this time and the luminance level after pulse (B) application.
Shown in The transmitted light amount after application of the pulse (B) in the low threshold portion in FIG. 6 is Ix%.

FIG. 7 shows the relationship between the luminance level after the application of the pulse (B) and the occurrence of flicker, and depends on the frame frequency f and the field frequency F (the number N of interlaced scans) as in FIG. In the four-pulse method, an arbitrary number of interlaced scans can be set. For example, assume that 30 interlaced scans are performed. Then, for example, when the amount of transmitted light after the pulse (B) is Ix%, there is a branch point where flicker occurs at the point A in FIG. 7, so that a frame frequency of about 20 Hz is required. If all the scanning lines are scanned uniformly, the frequency becomes about 13 Hz as described above, so that flicker occurs in the low threshold portion. On the other hand, since the luminance level of the high threshold portion after the application of the pulse (B) is approximately 0%, the point B in FIG. Therefore, in this case, the scanning order of the scanning lines is set such that the low threshold portion has a frame frequency equivalent to 20 Hz or higher and the high threshold portion has a frame frequency equivalent to 10 Hz or lower.

The temperature information of each scanning block detected by the temperature detecting element 136 in FIG. 2 indicates that only the uppermost A block among the scanning lines divided into five blocks shown in FIG. Assuming that the block temperature is T1 (<Tx), the MPU of the panel controller 134 calculates and weights the scanning frequency for obtaining a frame frequency that does not cause flicker for each block, as described above. Then, weighting information for setting the scanning frequency of each block of A: B: C: D: E to 2: 1: 1: 1: 1 is calculated, and the weighting information is calculated by the graphic controller 13.
Transfer to 5. The graphic controller 135 transfers the scan address and the image information to the panel controller 134 according to the weight information received from the panel controller 134. As a result, the frame frequency of the A block can be equivalent to 20 Hz, and the frame frequency of the B to E blocks can be equivalent to 10 Hz, so that good image quality without flicker can be obtained over the entire display element.

[0034]

FIG. 8 is a diagram showing driving waveforms in the pixel shift method. In the case of the pixel shift method, the pulse (B) 1H receives its own gradation information, but the pulse (D) 1H receives the gradation information of a physically adjacent scanning line.
The time required to scan one scanning line is 1H. In the ferroelectric liquid crystal of this embodiment, about 50 .mu.sec
For example, when a display element of XGA (1024 information lines × 768 scanning lines) is considered, if all the scanning lines are sequentially scanned, it takes about 38 msec to scan the entire display element. Takes time. This corresponds to about 26 Hz when converted to a frame frequency.

Here, as in the first embodiment, the process proceeds according to the flowchart of FIG. FIG. 7 shows the relationship between the luminance level after the pulse (B) and the occurrence of flicker, and depends on the frame frequency f and the field frequency F (the number of interlaced scans N) as in FIG. For example, when the amount of transmitted light after the pulse (B) is Ix%, the number of interlaced scans depends on the relaxation time in the pixel shift method, and the present embodiment requires a relaxation time of 200 μsec. The rest period during (D) is 4
H, that is, scanning is performed by dividing the display element into five blocks, and the number of interlaced scans is XGA (76).
8 scan lines), the number of interlaced scans is about 154. Then, since there is a branch point where flicker occurs at a point C in FIG. 7, a frame frequency of about 30 Hz is required. If all the scanning lines are uniformly scanned, the frequency is about 26 Hz as described above, so that flicker occurs in the low threshold portion. On the other hand, since the luminance level of the high threshold portion after the application of the pulse (B) is approximately 0%, there is a branch point where flicker occurs at a point D in FIG. Therefore, in this case, the scanning order of the scanning lines is set so that the low threshold portion has a frame frequency equivalent to 30 Hz or higher and the high threshold portion has a frame frequency equivalent to 10 Hz or lower.

As in the first embodiment, the temperature information of each scanning block detected from the temperature detecting element 136 in FIG. 2 is used only for the uppermost A block among the scanning lines divided into five blocks shown in FIG. Is the temperature Tx and the temperatures of the other four blocks are T1 (<Tx), the panel controller 1
The MPU 34 calculates and weights the scanning frequency for obtaining a frame frequency that does not cause flicker for each block as described above. Here, A: B: C: D:
Weighting information for setting the scanning frequency of each block of E to 2: 1: 1: 1: 1 is calculated, and the weighting information is transferred to the graphic controller 135. The graphic controller 135 transfers the scan address and the image information to the panel controller 134 according to the weight information received from the panel controller 134. Thus, the frame frequency of the A block is equivalent to 40 Hz, and
The frame frequency of the E block can be equivalent to 20 Hz, and a good image quality without flicker can be obtained over the entire display element.

[0037]

As described above, by using the present invention, a favorable display without flicker can be performed.

[Brief description of the drawings]

FIG. 1 is a diagram showing a processing flow according to an embodiment of the present invention.

FIG. 2 is a block diagram of a display device according to an embodiment of the present invention.

FIG. 3 is a communication timing chart of image information of the display device of FIG. 2;

FIG. 4 is a diagram showing a driving waveform of a four-pulse method according to the first embodiment of the present invention.

FIG. 5 is a diagram showing a change in the amount of transmitted light after application of a pulse (B) in the 4-pulse method and the pixel shift method.

FIG. 6 is a diagram showing a relationship between a temperature and a luminance level after application of a pulse (B).

FIG. 7 is a diagram illustrating a frame frequency setting method according to an embodiment of the present invention.

FIG. 8 is a diagram showing a driving waveform of a pixel shift method according to a second embodiment of the present invention.

FIG. 9 is a diagram showing driving characteristics of a ferroelectric liquid crystal cell.

FIG. 10 is a diagram showing a display state based on the driving characteristics of FIG. 9;

FIG. 11 is a diagram showing a change in driving characteristics depending on the temperature of a ferroelectric liquid crystal cell.

FIG. 12 is a diagram showing a driving waveform of the four-pulse method.

FIG. 13 is an explanatory diagram of a driving state by a four-pulse method.

FIG. 14 is a diagram showing a display state when the four-pulse method is used.

FIG. 15 is a schematic diagram of a ferroelectric liquid crystal cell in which a threshold distribution is formed in each pixel.

FIG. 16 is an explanatory diagram of a driving state by a pixel shift method.

FIG. 17 is a diagram showing a state of a relaxation time when a single pulse is applied.

FIG. 18 is a diagram showing the effect of crosstalk pulses on transmittance.

FIG. 19 is a diagram illustrating a relationship between a frame frequency, a field frequency, and flicker.

[Explanation of symbols]

81: glass, 82: liquid crystal, 83: information side electrode, 84:
Scanning side electrode, 85: base layer, 86: alignment film, 131: display element, 132: information line drive circuit, 133: scanning line drive circuit, 134: panel controller, 135: graphic controller, 136: temperature detection element.

Claims (5)

[Claims] A pixel is formed at an intersection of a scanning electrode group and an information electrode group provided on each electrode substrate with a ferroelectric liquid crystal sandwiched between two electrode substrates arranged opposite to each other. A ferroelectric liquid crystal display element formed with a threshold distribution in a pixel,
In a liquid crystal display device provided with a driving unit for performing gradation display on the liquid crystal display element, the driving unit changes a scanning frequency and / or a scanning order of scanning lines according to a temperature distribution of the liquid crystal display element. Liquid crystal display. 2. A pixel is formed at an intersection of a scanning electrode group and an information electrode group provided on each electrode substrate by sandwiching a ferroelectric liquid crystal between two electrode substrates arranged opposite to each other. In a driving method for performing gradation display on a ferroelectric liquid crystal display element having a threshold distribution formed in a pixel, a scanning frequency and / or a scanning order of scanning lines are changed according to a temperature distribution of the liquid crystal display element. Drive method to do. 3. The liquid crystal display device according to claim 1, wherein the number of pixels is at least two.
3. The driving method according to claim 2, wherein the scanning method is divided into one or more scanning blocks, and the scanning frequency is changed according to the temperature for each scanning block. 4. The driving method according to claim 2, wherein the scanning frequency and / or the scanning order is determined according to a table including a relationship between temperature information, one horizontal scanning period, and the number of interlaced scans. 5. The driving method according to claim 4, wherein the scanning frequency and / or the scanning order are determined and processed by a microprocessor unit.