JPH09105912A - Matrix type liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a matrix type liquid crystal display device in which a screen trailing phenomenon is prevent from occurring by preferentially utilizing the optical responsiveness of an antiferroelectric liquid crystal in a moving picture display. SOLUTION: A picture judgement signal output circuit 40 outputs a picture judgement signal to a row driving circuit 26 by judging whether a picture to be displayed is a still picture or a moving picture based on an analog B signal. The row driving circuit 26 changes over a holding voltage to a voltage suitable to a still picture display or a voltage suitable to a moving picture display by the holding voltage changeover circuit in the circuit based on the picture judgement signal and applies the holding voltage on row electrodes Y1 , Y2 ,..., Yn . At this time, the voltage suitable to the still picture display is selected by giving priority to the optical transmissivity of the untiferroelectric liquid crystal and besides the voltage suitable to the moving picture display is selected by giving priority to the optical responsiveness of the liquid crystal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a matrix type liquid crystal display device which performs matrix display by utilizing an antiferroelectric liquid crystal.

[0002]

2. Description of the Related Art Heretofore, as a matrix type liquid crystal display device of this type, there is a device which performs matrix display using an antiferroelectric liquid crystal, as disclosed in Japanese Patent Laid-Open No. 5-119746. The anti-ferroelectric liquid crystal has one anti-ferroelectric state (first stable state described later) and two ferroelectric states (second and third stable state described later) mutually with respect to voltage application. Form stably.

According to the above publication, a voltage (scanning signal) having a drive signal waveform shape shown in FIG. 37 (a) is applied to one electrode on both electrode substrates facing each other, and is applied to the electrode on the other electrode substrate. Applies a voltage (data signal) having the drive signal waveform shape shown in FIG. At this time, ON display (ferroelectric state) and OFF display (antiferroelectric state) are performed by a combination of a selection signal in the scanning signal and an ON signal and an OFF signal in the data signal. This ON signal and OFF signal are shown in FIG.
As shown in (b), the signals have the same amplitude but different polarities (the same applies to an embodiment described later).

Here, in the case of ON display,-(V
a + Vb) is applied for t hours, and then Va + Vb is applied for t hours. In case of OFF display,-(Va-Vb)
Is applied for t time, and then Va-Vb is applied. Therefore, the difference between the ON display voltage and the OFF display voltage is 2Vb. Further, it is assumed that the anti-ferroelectric liquid crystal is applied with a bipolar pulse such that a voltage of −V is applied for t time and a voltage V is applied for the subsequent t time. At this time, the voltage dependence of the light transmittance after 2 · t hours from the start of applying the voltage is as shown by the characteristic curve in FIG. 38.

When the OFF display has a transmittance of α% or less and the ON display has a transmittance of β% or more, the voltage to be applied between the pixel electrodes for OFF display is Vα or less, and the voltage between the pixel electrodes for ON display is The voltage to be applied to V becomes equal to or higher than Vβ. Therefore, Va is the midpoint between Vα and Vβ, that is, Va = 1 /
2 (Vα + Vβ), and Vb becomes half the difference between Vα and Vβ, that is, Vb = 1/2 (Vα−Vβ).

On the other hand, in the first field, the voltage applied to the pixel in the non-selected period has an amplitude of Vb with V0 as the center,
The pulse has a period of 2t or 4t. In the case of the second field, the polarities are reversed.

[0007]

By the way, during the non-selection period, for example, the holding period, pixel display (ON, OFF) is performed.
Together) must be maintained in good contrast. For this reason, the voltage during the holding period, that is, the holding voltage is usually fixed to a value that increases the light transmittance of the antiferroelectric liquid crystal described above. Therefore, the optical response time of the antiferroelectric liquid crystal becomes slow, for example, 180 ms.

On the other hand, it is known that antiferroelectric liquid crystal has an optical response characteristic that the response decreases when the light transmittance is increased, and conversely, the response increases when the transmittance is decreased. . Therefore, in the case of the holding voltage fixed as described above, in the still image display, even if the optical response is slow as described above, there is no problem, but in the moving image display, the light transmittance is high, and thus the antiferroelectric property is high. The optical response characteristics of the liquid crystal are deteriorated. As a result, there is a problem in that the moving image display is accompanied by a dragging phenomenon that makes the motion of the moving image trail, and the display quality is deteriorated.

On the other hand, the present inventor examined the relationship between the light transmittance and optical response characteristics of the antiferroelectric liquid crystal and the holding voltage in detail by experiments. Here, it is known that the afterimage is visible as a characteristic of the human eye in the range of the optical response time of about 80 ± 20 ms. Therefore, the response time of 80 ms is used as the threshold value for the occurrence of the screen drag phenomenon. It was decided to.

When the above-mentioned fixed holding voltage is used as a reference, the optical response characteristic of the antiferroelectric liquid crystal is examined in relation to the voltage of ± 1 (V).
The sampling result as shown in was obtained. According to this, in the range of the fixed holding voltage ± 1 (V), when the optical response time of the antiferroelectric liquid crystal is 80 ms or more, the screen dragging phenomenon occurs in the moving image display, and when the response time is less than 80 ms. It was found that the screen dragging phenomenon did not occur in moving image display.

Therefore, in the still image display, the good display contrast is given priority over the optical response of the antiferroelectric liquid crystal, and in the moving image display, the optical response of the antiferroelectric liquid crystal is given priority over the display contrast. For example, it was found that a good display contrast can be ensured in the still image display and the optical responsiveness of the antiferroelectric liquid crystal can be improved in the moving image display to prevent the screen drag phenomenon. However, in the case of displaying a moving image, it is necessary that the display contrast be such that an appropriate state can be secured even if the optical response of the antiferroelectric liquid crystal is enhanced.

Therefore, in the range of the optical response time of the antiferroelectric liquid crystal of 80 ms or more and the fixed holding voltage ± 1 (V), the relation between the light transmittance, the holding voltage and the signal voltage (column driving voltage) is shown. Upon examination, a characteristic curve A was obtained as shown in FIG. This characteristic curve A shows the relationship between the light transmittance of the antiferroelectric liquid crystal and the signal voltage with the holding voltage V _A as a parameter, and in consideration of the still image display, the light transmittance is increased and a good display contrast is secured. It is for.

Further, the optical response time of the antiferroelectric liquid crystal is
Range of less than 80 ms and above fixed holding voltage ± 1 (V)
, The relationship between light transmittance, holding voltage and signal voltage was investigated.
However, a characteristic curve B was obtained as shown in FIG.
This characteristic curve B is the holding voltage V _BAs a parameter
The relationship between the light transmittance of the ferroelectric liquid crystal and the signal voltage is shown in the video.
Considering the display, it is possible to maintain an appropriate display contrast.
In this state, the optical response speed of the antiferroelectric liquid crystal is increased and the screen is pulled.
This is to prevent the occurrence of the shear phenomenon. An example
For example, holding voltage V_BIs 5 (V) and the holding voltage V_AIs 6
(V).

In addition, when the voltage during the selection period is also examined, the voltage during the selection period, that is, the selection voltage, is ensured in order to secure a good display contrast state for the pixel display (both ON and OFF) during the selection period. Usually, the value is fixed so as to increase the light transmittance of the antiferroelectric liquid crystal described above. Therefore, the same problem as in the case of the fixed holding voltage occurs.

With respect to such a selection voltage, it was confirmed by experiments as in the case of the fixed holding voltage ± 1 (V) described above. As a result, it was found that the selection voltage also plays a substantially similar role to the holding voltage in preventing the occurrence of the above-mentioned screen drag phenomenon. In view of the above, the present invention is directed to a matrix type that prevents the occurrence of a screen drag phenomenon by preferentially utilizing the optical response characteristics of antiferroelectric liquid crystal in moving image display. An object is to provide a liquid crystal display device.

[0016]

SUMMARY OF THE INVENTION In order to achieve the above object, in the invention described in claim 1, the row driving voltage applied to each row electrode is a plurality of voltages which make the optical response of the antiferroelectric liquid crystal different. It is configured. Further, the voltage switching means switches the row driving voltage to a voltage having a high optical response of the antiferroelectric liquid crystal among the plurality of voltages when the display image changes from a still image to a moving image. And the row drive means
The voltage switched by the voltage switching means is applied to each row electrode as a row drive voltage.

Thus, when the displayed image changes from a still image to a moving image, the antiferroelectric liquid crystal is driven by the row drive voltage which is a voltage having high optical response. Therefore, the optical response of the antiferroelectric liquid crystal is enhanced, and the dragging phenomenon can be prevented from occurring in the display of moving images to improve the appearance of the display. Further, in the invention according to claims 2 to 10, at least one of the second and third voltages applied to each row electrode is constituted by a plurality of voltages which make the optical response of the antiferroelectric liquid crystal different. ing. Further, when the display image changes from a still image to a moving image, the voltage switching means sets at least one of the second and third voltages to a voltage having a high optical responsiveness of the antiferroelectric liquid crystal among the plurality of voltages. Switch. Then, the row driving means applies the voltage switched by the voltage switching means to each row electrode as a row driving voltage.

As a result, when the displayed image changes from a still image to a moving image, the antiferroelectric liquid crystal is driven by the second or third voltage having a high optical response. Therefore, the optical response of the antiferroelectric liquid crystal is enhanced, and the dragging phenomenon can be prevented from occurring in the display of moving images to improve the appearance of the display. Here, in the invention as set forth in claim 3, the voltage switching means includes an image determining means for determining whether or not the display image is a moving image based on the input video signal. Then, when the image determination unit determines the moving image, the voltage switching unit switches the voltage.

According to this, when it is determined that the display image is a moving image, the voltage switching means can automatically switch the voltage. In this case, as in the fourth aspect of the invention, when the image determination unit determines that the image is a moving image, the voltage switching unit switches the voltage within the vertical blanking period specified by the vertical synchronization signal. If you go
The voltage is switched by the voltage switching means within the original non-display period. Therefore, it is possible to more reliably prevent the occurrence of the dragging phenomenon in the moving image display in the original display period.

Further, in the invention described in claim 5, the image determining means determines that the image is a moving image when the number of screens per frame is 1 frame or more based on the input video signal. Therefore, it is possible to make the determination of a moving image more reliable. Further, in the invention according to claim 6, the plurality of voltages are set within the hysteresis characteristic region representing the relationship between the light transmittance of the antiferroelectric liquid crystal and the voltage. Therefore, it is possible to effectively utilize the hysteresis characteristic of the antiferroelectric liquid crystal and prevent the occurrence of the dragging phenomenon in the moving image display as described above.

In this case, if the plurality of voltages are set within the range of the light transmittance of 10% to 90% in the hysteresis characteristic region as in the invention described in claim 7, Further effective utilization of the hysteresis characteristics of the antiferroelectric liquid crystal can be ensured within the range where the OFF state and the ON state can be clearly specified. Further, in the invention according to claim 8, a plurality of voltages are high optical response voltages that represent optical response higher than optical response corresponding to human visual perception limit of afterimage. The anti-ferroelectric liquid crystal has a low optical response voltage that exhibits a lower optical response than the optical response corresponding to the human afterimage visibility limit.

Therefore, when the still image changes to a moving image, the high optical response voltage serves as a row driving voltage. Therefore, the occurrence of the dragging phenomenon in the moving image display can be prevented more reliably. In this case, as in the invention described in claim 9, the optical response corresponding to the afterimage visibility limit is 80 ± 20 m in the optical response time of the antiferroelectric liquid crystal.
If s, it is possible to more reliably prevent the occurrence of the dragging phenomenon in the moving image display in consideration of the variation in the human visual acuity.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) FIG. 1 shows an overall schematic configuration of a liquid crystal display device of the present embodiment. The liquid crystal display device includes a liquid crystal panel 1 and a control device 2 that drives the liquid crystal panel 1. The liquid crystal panel 1 is shown in FIG.
And, as shown in FIG. 2, both electrode substrates 11, which are superposed on each other via a strip-shaped seal and a spacer (not shown),
The antiferroelectric liquid crystal 13 is sealed between the two electrode substrates 11 and 12. The gap between the two electrode substrates 11 and 12 is uniformly maintained at about 2 μm by the spacers.

The electrode substrate 11 has a transparent glass plate 11a, and on the inner surface of the glass plate 11a, there are m transparent strips made of ITO (Indium Tin Oxide) or tin oxide via a color filter layer 18. The conductive film 11b and the alignment film 14 are sequentially formed. On the other hand, the electrode substrate 12 has a transparent glass plate 12a, and an n-line transparent conductive film 12b and an alignment film 15 are sequentially formed on the inner surface of the glass plate 12a. Both alignment films 14 and 15 are subjected to rubbing treatment.

Here, the m strips of transparent conductive film 11b of the electrode substrate 11 are the m strips of column electrodes X ₁ , X ₂ , ..., X _{m in FIG.}
On the other hand, on the other hand, the n-shaped transparent conductive film 12 of the electrode substrate 12
b corresponds to the _n row electrodes Y ₁ , Y ₂ , ..., Y _n in FIG. In addition, n row electrodes Y ₁ , Y ₂ , ..., Y _n
, M row electrodes X ₁ , X ₂ , ..., X _m together with mx
The pixels are formed in a matrix so as to form _n pixels G _1,1 , G _1,2 , ..., G _{m, n} .

Polarizing plates 16 and 17 are attached to the outer surfaces of the two electrode substrates 11 and 12, respectively, and these polarizing plates 16 and 17 are formed in crossed Nicols at their absorption axes. It is located in a position. Therefore, when the antiferroelectric liquid crystal 13 is in the first stable state, both polarizing plates 16 and 17 are adapted to be extinguished. The control device 2 controls the column electrodes X ₁ , X ₂ , ..., X _m and the row electrodes Y ₁ , Y ₂ , ..., Of the liquid crystal panel 1 based on a video signal (analog RGB signal) input from the outside. By applying a voltage to Y _n , the grid-like pixels of the liquid crystal panel 1 are driven, and an image corresponding to a video signal is displayed in full color on the liquid crystal panel 1. Hereinafter, the configuration of the control circuit 2 will be described in detail.

This control device 2 is, as shown in FIG.
A level correction circuit 22 to which an analog RGB signal is input from the outside, a control circuit 24 to which a synchronization signal (a vertical synchronization signal and a horizontal synchronization signal) is input from the outside, a signal conversion connected to the level correction circuit 22 and the control circuit 24 A circuit 23, a column drive circuit 25 connected between the signal conversion circuit 23 and the control circuit 24 and each column electrode X ₁ , X ₂ , ..., X, and an analog B signal of the analog RGB signals are input. Image judgment signal output circuit 4
0, and the row drive circuit 26 connected between the image determination signal output circuit 40 and the control circuit 24 and each row electrode Y ₁ , Y ₂ , ..., Y _n .

The level correction circuit 22 corrects the level of the input analog RGB signal and converts it into an analog RGB signal that matches the characteristics of the antiferroelectric liquid crystal 13. The signal conversion circuit 23 either passes the analog RGB signal converted by the level correction circuit 22 as it is or outputs it after inversion. The inversion of the analog RGB signal is selected by the field signal FI output from the control circuit 24. To be done.

In addition to the field signal FI, the control circuit 24 receives the first synchronization signal from the outside in response to the synchronization signal input from the outside.
To third clock signals CL1, CL2, CL3, and the scan signal constituting a later-described seven voltage levels (V _1, V ₂₁ or V _22, -V ₂₁ or -V _22, V _3, -V
_3- bit scanning signal D corresponding to ₃ , V ₄ , -V ₄ )
1, D2, D3 are produced and output.

The column driving circuit 25 is composed of a shift register 27 and an analog data latch 28 for applying a column driving signal (column driving voltage) to each column electrode. More specifically, as shown in FIG. 3, the column driving path 25 includes a pair of shift registers 27 and two stages of sample hold circuits 28a and 2a.
8b. Analog RG from the signal conversion circuit 23
The B signal is sequentially latched by the first-stage sample hold circuits SH11, SH12, ..., SH1m in synchronism with the first clock signal CL1 generated by the control circuit 24, and after latching the signal for one row, the signal is held. To be done. The signal held by the first-stage sample hold circuit 28a is synchronized with the second clock signal CL2 generated by the control circuit 24, and the next-stage sample hold circuit SH2.
1, SH22, SH23, ..., SH2m are sequentially latched and output to the respective column electrodes as the column drive signal.

Then, the column driving circuit 25 repeats the above operation to generate a driving waveform as shown in FIG. That is, the RGB column drive signals X ₁ , X ₂ , ..., X _m are output in synchronization with the first clock signal CL1. Here, the column drive signal has a polarity as shown in FIG. 37 (b) corresponding to ON / OFF display, and the amplitude is shown in FIG. 4 (a) in the case of this embodiment. It is V ₅ . Further, the column drive signals X ₁ , X ₂ , X _m are configured such that the polarities thereof are inverted in the first field and the second field corresponding to the period of t in FIG. 4A.

The image determination signal output circuit 40 includes an image determination circuit 41 as shown in FIG. 5, and the image determination circuit 41, based on the analog B signal, changes the number of frames which changes within a fixed time by one. It is determined whether or not the time is equal to or more than a frame (for example, the time required to scan 525 scanning lines specified by the analog B signal). When the number of frames is one or more, the image determination circuit 41 determines that it is a moving image. On the other hand, when the number of frames is less than 1,
The image determination circuit 41 determines that the image is a still image.

Low-pass filter 42 (hereinafter LPF 42)
Is a low frequency component (a component corresponding to a still image or a moving image) in the image determination result from the image determination circuit 41.
To generate a filtered signal. Absolute value circuit 43
Takes the absolute value of the filter signal from the LPF 42 and generates an absolute value signal. The waveform shaper 44 is the absolute value circuit 4
The absolute value signal from 3 is waveform-shaped and an image determination signal is output.

The row drive circuit 26 applies a scanning signal to each row electrode, and therefore the shift register circuit 29 and the driver 3 are provided.
It consists of 0. As shown in FIG. 6, the shift register circuit 29 includes three sets of shift registers 29a, 29b, and 2.
It consists of 9c. The driver 30 includes a large number of decoders 30a according to the number n of row electrodes, and a large number of switch circuits 3 including seven analog switches for each decoder 30a.
0b, the power supply circuit 30c, and the holding voltage switching circuit 30.
d.

Each shift register 29a, 29b, 29c
Is the third clock signal generated by the control circuit 24
Scan signal D in synchronization with signal CL3₁, D_Two, D_ThreeCapture
No. Then, the shift registers 29a, 2 corresponding to each row
9b and 29c are data decoded by each decoder 30a
Scanning voltage level (V₁, V_{twenty one}Or V_{twenty two}, -V _{twenty one}
Or -V_{twenty two}, V_Three, -V_Three, V_Four, -V_FourCorresponding to
Turn on the analog switch to erase each row drive electrode, spare
It is output as a scanning signal for selection, selection, and holding.

Here, V ₁ , V ₂₁ , V ₂₂ , -V ₂₁ , -V
_{22, V 3, -V 3,} V 4, -V 4 are, as shown in FIG. 7, the light transmittance of 10 in the hysteresis characteristic region representing a relationship between the applied voltage and the antiferroelectric liquid crystal light transmittance The voltage is set in the power supply circuit 30c with a voltage within the range of 90% to 90%. The reason why the voltage is within the hysteresis characteristic region is that the anti-ferroelectric liquid crystal 13 is accurately driven by effectively utilizing the hysteresis characteristic of the anti-ferroelectric liquid crystal 13. Further, the light transmittance is 10% to 90%.
The reason why the voltage is within the range of% is to utilize the hysteresis characteristic of the antiferroelectric liquid crystal 13 more effectively.
However, the voltage V ₂₁ is the holding voltage V _A in FIG.
The voltage V ₂₂ is the holding voltage V _B in FIG.

Then, the row drive circuit 26 repeats the above operation to generate drive waveforms as shown in FIGS. 8 (a), 8 (b) and 8 (c). That is, the third clock signal CL3
The scanning signals Yj-1, Yj, and Yj + 1 are output in synchronization with. These scan signals correspond to each row,
It has a voltage level corresponding to any one of a pre-selection period, a selection period, a holding period, and an erasing period, which will be described later.
Specifically, the voltage level corresponds to each period as shown in FIG. Then, the selection periods for selecting the display states of the rows are sequentially generated in each row with a delay of 2t as shown in FIG. That is, as shown in FIG. 8B, the selection period sequentially shifts in synchronization with the second clock signal CL2.

Next, the one-screen display time is 33.3 msec.
(30Hz at screen rewriting frequency), 2 row electrodes
Scan duty ratio 1 / N for 20 and 960 column electrodes
The operation of the liquid crystal display device in the case of (N = 262) will be described. Pixels G _{i, j-1 of} this liquid crystal display device,
G _{i, j} and G _{i, j + 1} are provided with the drive signal waveform-shaped voltage as shown in FIG. The voltage having the waveform of the drive signal as shown in () is applied to the row electrodes.

However, prior to this application, the image determination signal output circuit 40 determines whether the image is a still image or a moving image based on the analog B signal and outputs an image determination signal to the row drive circuit 26. Then, the holding voltage from the power supply circuit 30c is switched to a different value by the holding voltage switching circuit 30d depending on the content of the image determination signal, that is, whether it is a moving image or a still image, so that the holding voltage is included in the voltage applied to the row voltage. The voltage also varies depending on whether it is a moving image or a still image.

Here, as shown in FIG. 8A, the row drive signal applied to the row electrode is composed of a preliminary selection period, a selection period, a holding period and an erasing period. In the pre-selection period, the antiferroelectric liquid crystal is in the first stable state (display erased state) or a state according to the first stable state (an intermediate state between the first stable state and the second or third stable state) in the selection period. It is an object of the present invention to shorten the response time when the second stable state or the third stable state is changed from (corresponding to the transition state described in the claims). Here, in both the second stable state and the third stable state, the liquid crystal is in a transparent state (display O).
In each state, the directions of application of the electric field applied to the liquid crystal are opposite.

The selection period determines the display state of the pixel in combination with the column drive signal applied to the column electrode. The holding period is for maintaining the display state determined in the selection period. During the erase period, the display state is set to the first
It is for returning to a stable state or a state according to the first stable state. The selection period and the holding period are the same as those disclosed in JP-A-5-119746.

As shown in FIG. 8A, in the preliminary selection period, the peak value is V ₃ and the pulse width is t (t = 31.8 μse).
It is composed of two bipolar pulses of c). The selection period is
It is composed of two bipolar pulses having a peak value of V ₄ and a pulse width of t, and has a phase opposite to that of the preliminary selection period. In the holding period, the peak value is V ₂₁ or V ₂₂ , the polarity is the same as in the latter half of the selection period, and the pulse width is 2 · t · (N-2-
R) of one unipolar pulse. The erase period is
It is composed of one unipolar pulse having a peak value of V1 and a pulse width of 2 · t · R. R is obtained as a value obtained by dividing the erase period by 2t.

Further, the row drive signals (row drive voltages) applied to the row electrodes have their polarities inverted with respect to adjacent row electrodes in order to reduce the flicker of the image. As shown in FIG. 4A, the column drive signal (column drive voltage) applied to the column electrode is composed of two bipolar pulses having a peak value of V ₅ and a pulse width of t. An image having a halftone can be displayed by adjusting the crest value V ₅ and the phase according to the image to be displayed.

Pixels G _{i, j− 1} , G _{i, j} and G are obtained by combining the above scanning signals (row driving signals) and column driving signals.
_The antiferroelectric liquid crystal of _{i, j + 1} has the structure shown in FIG.
A drive voltage having a waveform shape as shown in (a), (b), and (c) is applied. In these waveforms, G _{i, j-1 is} bright (O
N) state, G _{i, j} is a dark (OFF) state, and G _{i, j + 1 is a} bright (ON) state.

The pixels G _{i, j−1} , G _{i, j} , and G _{i, j + 1} are respectively shifted by a period of 2t, and each voltage of the pre-selection period, the selection period, the holding period, and the erasing period is changed. A signal is applied.
Here, the voltage waveform of the pre-selection period is a bipolar two-pulse whose phase is opposite to that of the voltage waveform of the selection period. Before switching the state of the liquid crystal in the selection period, the state of the liquid crystal in the pre-selection period is changed. Can be placed in the previous state (transition state). Therefore, in the selection period, it is possible to shift to a desired liquid crystal state with good responsiveness even at a relatively low voltage.

[0046] Here, the pixel G _i, the display state of _j is one line before the pixel G _i, it is desirable not affected by the display data of _j-1, therefore, the scanning in the pre-selection period signal voltage V ₃ Is set to a voltage slightly lower than (V ₄ -2 · V ₅ ). This voltage (V ₄ -2 · V ₅ ) corresponds to the threshold voltage for switching the liquid crystal to the bright / dark state.

The liquid crystal display device was driven as described above.
The contrast in this case is as shown in FIG. Preliminary election
Scan signal voltage V in selected period_ThreeAnd running during the selection period
Check signal voltage V_FourThe contrast is the same when
High, V_ThreeThe lower the, the lower the contrast
You. In addition, the voltage V of the column drive signal_FiveFigure 1 shows the relationship between temperature and temperature
It is shown in FIG. The higher the temperature, the better the response of the liquid crystal.
Therefore, in this case V _FiveCan be lowered,
In this case, V_ThreeBecomes higher V_FiveTo lower
Can be. This is V_ThreeThe higher the
The response is faster, and V_FiveRespond enough even if lowered
It means that it can improve the sex. this
Like, V_FiveBy reducing the pixel
The fluctuation of the voltage applied to the
Therefore, the display can be held well. High as a result
A high contrast ratio can be obtained.

Next, the case where the pixel G _{i, j is in the} bright (ON) state will be described. In this case, a drive voltage having a waveform shape as shown in FIG. 11 is applied to the pixel. In the preliminary selection period, the state is based on the first stable state, and in the selection period, it is the third stable state. During the holding period, the state according to the third stable state is maintained based on the holding voltage ± V ₂₁ ± V ₅ (or ± V ₂₂ ± V ₅ ), and during the erasing period, the state according to the third stable state is changed to the first stable state. The state becomes a state or a state according to the first stable state.

In the positive field period following the above negative field, the state is based on the first stable state in the preliminary selection period, and is in the second stable state in the selection period (a voltage whose polarity is inverted for each field is applied. For). During the retention period, the state according to the second stable state is maintained based on the retention voltage ± V ₂₁ ± V ₅ (or ± V ₂₂ ± V ₅ ), and during the erase period, the state according to the second stable state is changed to the first stable state. Alternatively, it becomes a state according to the first stable state. 1 in both positive and negative fields
The screen is configured. Here, regarding the light transmittance of the antiferroelectric liquid crystal 13, as shown in FIG. 11B, the light transmittance is different between the still image and the moving image in the holding period.

In the case of dark (OFF) display, the pixel shown in FIG.
A drive voltage having a waveform shape as shown in is applied. During the pre-selection period, the state conforms to the first stable state, and during the selection period, the state conforms to the first stable state. First in retention period
The state according to the stable state is maintained, and during the erase period, the state according to the first stable state changes to the first stable state or the state according to the first stable state.

When the driving method as described above is used, V ₃ is set so as to be in a state immediately before the transition from the state according to the first stable state to the second stable state during the preliminary selection period. As shown in FIG. 14, the peak value V ₅ of the column drive signal applied to the column electrode for determining ON / OFF of the pixel can be reduced as compared with the conventional drive method having no preliminary selection period. As a result, the fluctuation of the voltage applied to the pixel during the holding period is reduced, ON display and OFF display can be held well, ON brightness is high, and OFF brightness can be low. Therefore, as shown in FIG. 13, a higher contrast ratio can be obtained as compared with the conventional driving method.

In this case, as described above, the holding voltage switched by the holding voltage switching circuit 30d based on the output of the image determination signal output circuit 40 depending on whether the image to be displayed is a still image or a moving image is either V ₂₁ or V ₂₂ . become. Therefore, in the case of a still image, a high light transmittance of the antiferroelectric liquid crystal 13 is secured, while in the case of a moving image, the light transmittance of the antiferroelectric liquid crystal 13 is higher than that of a still image. The optical response will be improved while keeping it low. As a result, in the case of a still image, the display contrast is increased, while in the case of a moving image, the optical responsiveness of the antiferroelectric liquid crystal is increased more than the display contrast, thereby eliminating the dragging phenomenon of the moving image. The appearance of the display can be improved.

Various waveforms can be used as the scanning signal voltage waveforms in the preliminary selection period and the selection period. Examples of this waveform are shown as modified examples in FIGS. FIG. 15 shows the voltage V during the preliminary selection period.
₃ is a one-pole pulse waveform. FIG. 16 shows a pulse waveform having a polarity opposite to that of FIG. FIG.
In FIG. 7, bipolar 2 pulses in the pre-selection period are reversed in polarity from those shown in FIG. In FIG. 18, the voltage V _{4 in the} selection period has a one-pole pulse waveform in contrast to that shown in FIG. In FIG. 19, the selection period is a one-pole pulse waveform and the preliminary selection period is a bipolar two-pulse. In FIG. 20, the bipolar two pulses in the preselection period are reversed in polarity from those shown in FIG. FIG.
The pulse waveform of one pole in the preliminary selection period has the opposite polarity to that shown in FIG.

Here, as shown in FIGS.
The voltage during the holding period is V ₂₁ or V depending on whether it is a still image or a moving image.
_{It is set to 22} . Also, various waveforms can be used for the ON signal and the OFF signal of the drive signal. 22 to 25 show examples of this waveform as modified examples. In these figures, the waveforms in the positive and negative fields have opposite polarities.

In FIG. 22, the first half period is 0 level and the pulse signal is formed in the second half period. In FIG. 23, the OFF signal is set to 0 level as compared with the one shown in FIG. In FIG. 24, a pulse signal is formed for a period of 2t. FIG.
In contrast to what is shown in FIG. 24, the OFF signal is set to 0 level.

The drive signals shown in FIGS. 24 and 25 are as shown in FIG.
21. The effect is particularly high in combination with the scanning signal in which the selection period shown in FIG. 21 has a pulse waveform of one pole. In addition, FIG.
Even if the voltage waveform shown in FIG. 25 is used, the same effect as that of the first embodiment can be obtained. (Second Embodiment of the Invention) Next, a second embodiment of the present invention will be described with reference to FIGS.

In the second embodiment, instead of the control circuit 2 (see FIG. 1) described in the first embodiment,
As shown in FIG. 26, the use of the control circuit 2A is characteristic in its configuration. The control circuit 2A changes the voltages of the pre-selection period, the selection period, and the holding period described above according to the temperature of the liquid crystal panel 1 to obtain good display quality at the normal driving temperature of the display state of the liquid crystal panel 1. Achieves high contrast at low temperature driving while securing the same, and makes the holding voltage different depending on whether it is a still image or a moving image, giving priority to the light transmittance of the antiferroelectric liquid crystal in the still image and antiferroelectricity in the moving image. It has been adopted in order to give priority to the optical response of the organic liquid crystal.

Therefore, in the control circuit 2A, the control circuit 2A includes the temperature detection circuit 31 and the temperature correction control circuit 32.
And a column drive signal temperature correction circuit 33 are additionally employed. The temperature detection circuit 31 includes a thermistor 31a having a negative temperature coefficient of resistance (NTC),
The thermistor 31a is attached to the liquid crystal panel 1 at a position where it is easy to detect the temperature of the antiferroelectric liquid crystal 13.
The thermistor 31a is grounded at one terminal thereof, and the other terminal of the thermistor 31a is connected to the resistor 31b.
Through to the positive terminal of the DC power supply.

Therefore, the thermistor 31a detects the temperature of the antiferroelectric liquid crystal 13 and divides the voltage + Vb of the DC power source by operating in cooperation with the resistor 31b with an internal resistance value inversely proportional to the temperature, and A temperature detection voltage representing the temperature of the ferroelectric liquid crystal 13 is generated. As shown in FIG. 27, the temperature correction control circuit 32 includes an AD converter 32a. The AD converter 32a digitally converts the temperature detection voltage from the temperature detection circuit 31 into a microcomputer. 32b.

The microcomputer 32b executes the computer program according to the flow chart shown in FIG. 28, and according to the temperature detection voltage digitally converted by the AD converter 32a, temperature compensation table data shown in FIG. Based on the above, the arithmetic processing for searching and outputting each voltage in the pre-selection period, the selection period and the holding period described above is performed. In addition, the voltage is calculated in the pre-selection period so as to be 60% of the voltage on the characteristic curve L1.

The temperature compensating table data represents the relationship between the temperature of the antiferroelectric liquid crystal 13 and the voltages of the selection period and the holding period and the voltage of the column drive signal as table data by means of respective characteristic curves. . Here, the characteristic curve L1 represents the relationship between the temperature of the antiferroelectric liquid crystal 1 and the voltage during the selection period, and the characteristic curve L2A represents the temperature of the antiferroelectric liquid crystal 13 considering the still image and the voltage during the holding period. The characteristic curve L2B represents the relationship between the temperature of the antiferroelectric liquid crystal 13 and the voltage during the holding period in consideration of the moving image, and
The characteristic curve L3 represents the relationship between the temperature of the antiferroelectric liquid crystal 13 and the voltage during the holding period.

The relationship between the voltages of the characteristic curves L1, L2A, and L3 and the temperature of the antiferroelectric liquid crystal 13 is different at that temperature in consideration of the relationship between the temperature and viscosity of the antiferroelectric liquid crystal 13. The ferroelectric liquid crystal 13 is set so as to be driven in an optimal contrast and display state. Regarding the relationship between the characteristic curve L2B and the temperature of the antiferroelectric liquid crystal 13, the antiferroelectric liquid crystal 13 has a high optical property at that temperature in consideration of the relationship between the temperature and the viscosity of the antiferroelectric liquid crystal 13. It is set to be driven in a display state in which responsiveness is exhibited and the dragging phenomenon of a moving image is eliminated. The voltage in the preliminary selection period is set to a predetermined ratio (for example, 60%) of the voltage in the selection period (voltage on the characteristic curve L1). The temperature compensation table data is stored in advance in the ROM of the microcomputer 32b.

The DA converter 32c converts the output from the microcomputer 32b into an analog signal and applies it to the column drive signal temperature correction circuit 33 and the power supply circuit 30c (FIG. 27).
And FIG. 30). The column drive signal temperature correction circuit 33 includes automatic variable gain amplifiers 33a to 33c,
Each of the amplifiers 33a to 33c amplifies the converted RGB signal from the level correction circuit 22 according to its gain and outputs it to the signal conversion circuit 23.

Automatic variable gain amplifiers 33a to 33c
The respective gains are automatically adjusted in accordance with the analog output from the DA converter 32c so that the amplified outputs of the automatic variable gain amplifiers 33a to 33c become the voltage on the characteristic curve L3. The power supply circuit 30c corrects each voltage in the selection period and the holding period so as to be a voltage on each characteristic curve L1, L2A (or L2B) based on the analog output from the temperature correction control circuit 32. Other configurations are the same as those of the first embodiment.

In the second embodiment configured as described above, the microcomputer 32b performs the initialization process in step 41 of FIG. 28 when the execution of the computer program is started. Here, when the temperature of the antiferroelectric liquid crystal 13 detected by the temperature detection circuit 31, that is, the temperature detection voltage is digitally converted by the A / D converter 32a, this voltage is supplied to the microcomputer 32b in step 42. Is entered.

Next, at step 43, a voltage search is performed according to the temperature detection voltage at step 42 based on the temperature compensation table data of FIG. In this case, based on the characteristic curves L1, L2A, L2B, and L3, the voltage and the signal voltage in the selection period and the holding period are determined according to the temperature detection voltage in step 42, respectively. Further, 60% of the voltage in the selection period thus determined is calculated as the voltage in the preliminary selection period.

After that, in step 44, each voltage of the selection period and holding period determined in step 43 and the voltage of the calculated preliminary selection period are analog-converted by the DA converter 32c and output to the power supply circuit 30c. At the same time, the signal voltage is analog-converted by the D-A converter 32c and output to the column drive signal temperature correction circuit 33. Then, in the column drive signal temperature correction circuit 33, the gains of the amplifiers 33a to 33 drive the amplified outputs of the amplifiers 33a to 33c on the characteristic curve L3 in accordance with the analog output from the DA converter 32c. It will automatically adjust to the voltage.

Therefore, the amplifiers 33a to 33c are
According to the automatic adjustment gain, the converted RGB signal from the level correction circuit 22 is amplified and output to the signal conversion circuit 23. Further, the power supply circuit 30c sets the voltages in the selection period and the holding period to the voltages on the characteristic curves L1 and L2A (or L2B) based on the analog output of the DA converter 32c. Further, the power supply circuit 30c corrects the voltage in the preliminary selection period based on the analog output from the temperature correction control circuit 32 so as to be 60% of the voltage on the characteristic curve L1.

Therefore, each amplified output from the column drive signal temperature correction circuit 33 is the same as in the first embodiment,
Each column electrode X ₁ via the conversion circuit 23 and the column drive circuit 25,
..., X _m is given as a column drive signal. Further, the correction voltages from the power supply circuit 30c during the preliminary selection period and the selection period are transmitted through the switch circuits 30b to the column electrodes Y ₁ ,.
..., is applied to the Y _n, and each column electrode Y ₁ through the switch circuits 30b to the original switching action correction voltage retention period from the power supply circuit 30c is above the holding voltage switching circuit 30d, · · · , Y _n . As a result, the display of ON and OFF of the liquid crystal panel 1 is driven.

In this case, the voltages in the selection period, the pre-selection period and the holding period, and the column drive voltage are values corrected according to the temperature of the antiferroelectric liquid crystal 13 based on the temperature compensation table data in FIG. 31), it is possible to secure good contrast and display quality in a still image and a high optical response of the antiferroelectric liquid crystal in a moving image over a wide temperature range. . Therefore, similar to the first embodiment, the display quality of the still image in the normal driving temperature region is maintained good without increasing the voltages in the selection period, the preliminary selection period, the holding period, and the column driving voltage. At the same time, good contrast can be ensured even in the low temperature region, and the response speed of the moving image in the normal driving temperature region can be kept good to prevent the occurrence of the dragging phenomenon.

The scanning signal voltage waveforms in the pre-selection period, the selection period and the holding period in the second embodiment may be modified to use various waveforms as in the first embodiment. You can FIG.
The other modification of the said 2nd Embodiment is shown. In this modification, steps 45 to 47 are added between both steps 42 and 43 of the flowchart of FIG. The liquid crystal panel 1 also includes a heater (not shown) for heating the antiferroelectric liquid crystal 13. Along with this, the temperature correction control circuit 32 also performs the driving process of the heater (see the chain double-dashed line in FIG. 26). Other configurations are the same as those of the second embodiment.

In this modified example having such a configuration, as in the second embodiment, when the temperature detection voltage is input from the AD converter 32a to the microcomputer 32b in step 42, the temperature is detected. In step 45, PID calculation processing is performed a plurality of times based on the difference between the temperature corresponding to the detected voltage and the set temperature of the heater (hereinafter referred to as heater set temperature) corresponding to the target temperature of the antiferroelectric liquid crystal 13.

If the PID calculation processing value is not the heater set temperature, NO is determined in step 46. Then, in step 47, the heater drive output is output to the heater. Therefore, this heater generates heat to heat the antiferroelectric liquid crystal 13 to the heater set temperature. On the other hand, if the PID calculation processing value is the heater set temperature, the determination in step 46 is YES.

Then, in step 43, the second
Based on the temperature compensation table data described in the embodiment, the voltage search is performed according to the heater set temperature, that is, the target temperature of the antiferroelectric liquid crystal 13. In this case, based on the characteristic curves L1, L2A, L2B, and L3, the voltages and signal voltages in the selection period and the holding period are determined according to the heater set temperature. Further, 60% of the voltage in the selection period thus determined is calculated as the voltage in the preliminary selection period.

As a result, while maintaining the temperature of the antiferroelectric liquid crystal 13 at the target temperature, depending on whether the target temperature is high or low,
Substantially the same effects as those of the second embodiment can be achieved. (Third Embodiment of the Invention) Next, a third embodiment of the present invention will be described with reference to FIGS. In the third embodiment, the image determination signal output circuit 4
The configuration characteristic is that the image determination signal output circuit 40A is adopted instead of 0.

The image determination signal output circuit 40A is shown in FIG.
As shown in (a), the image determination signal output circuit 40
In, a D-type flip-flop 45 is additionally adopted. This flip-flop 45 is used by the waveform shaper 4
The image determination signal from No. 4 is output from the output terminal Q in response to the rising edge of the vertical synchronizing signal (see FIG. 34 (b)). This means that the image determination signal output circuit 40A outputs the image determination signal during the vertical blanking period. The high level of the image determination signal from the waveform shaper 44 corresponds to a moving image. Other configurations are the same as those of the first embodiment.

According to the third embodiment thus configured, the timing at which the holding voltage is switched by the holding voltage switching circuit 30d based on the output of the image determination signal output circuit 40A is the vertical blanking period of the liquid crystal display device. Since it is performed within the non-display period, the output of this holding voltage through each switch circuit 30b is also performed within the non-display period. Therefore, the occurrence of the dragging phenomenon of the moving image is prevented within the non-display period, and as a result, the occurrence of the dragging phenomenon of the moving image can be prevented more reliably in the original display period of the liquid crystal display device.

In each of the above embodiments, an example in which a still image or a moving image is determined based on a video signal and one of the holding voltages V _A and V _B is automatically selected has been described. However, if it is known in advance whether the image is a still image or a moving image, one of the holding voltages V _A and V _B may be selected by a manual operation such as a manual switch. Further, in carrying out the present invention, as described in each of the above-described embodiments, the holding voltages are not limited to the holding voltages V _A and V _B , but a plurality of holding voltages may be applied to each of the holding voltages V _A and V _B. You may prepare and apply this invention and implement. In this case, the two or more holding voltages are values within a hysteresis characteristic region that represents the relationship between the light transmittance of the antiferroelectric liquid crystal 13 and the applied voltage, or a value within the range of light transmittance of 10% to 90%. The present invention may be carried out by setting as.

Here, when the image to be displayed changes from a moving image to a still image, the higher voltage of the plurality of voltages corresponding to the holding voltage V _A is selected and switched by the holding voltage switching circuit 30d. Further, when the image to be displayed changes from a still image to a moving image, the lower voltage of the plurality of voltages corresponding to the holding voltage V _B is selected and switched by the holding voltage switching circuit 30d.

Further, in each of the above-described embodiments, the example in which V _A and V _B are adopted as the holding voltages has been described, but instead of this, both selection voltages V ₄₁ and V ₄₂ corresponding to the selection voltage V ₄ are used. May be adopted and implemented. In this case, both selection voltages V ₄₁ and V ₄₂ correspond to both holding voltages V _A and V _B , and the selection voltage V ₄₁ is 27 (V), and the selection voltage V ₄₂
Is 29 (V). It should be noted that both holding voltages V _A and V _B and both selection voltages V ₄₁ and V ₄₂ may be switched to one of the holding voltages V _A and V _{B in} the same manner.

Further, in implementing the present invention, in each of the above-described embodiments, 80 ms is adopted as the afterimage visual recognition limit of a person, but the present invention is not limited to this, and 80 ± 20 ms may be adopted. In implementing the present invention, the preliminary selection period in each embodiment may be omitted.

Further, each step in the flow charts of the second embodiment and its modification is
The function executing means may be realized by a hard logic configuration.

[Brief description of the drawings]

FIG. 1 is a first of a matrix type liquid crystal display device according to the present invention.
2 is an overall view showing the configuration of the embodiment of FIG.

FIG. 2 is a schematic sectional view of the liquid crystal panel of FIG.

3 is a configuration diagram showing a specific circuit of a column drive circuit 25 in FIG.

FIG. 4 is a timing chart of each signal in the column driving circuit 25.

5 is a detailed block diagram of the image determination signal output circuit of FIG.

6 is a configuration diagram showing a specific circuit of a row drive circuit 26 in FIG.

FIG. 7 is a hysteresis characteristic diagram showing the relationship between the light transmittance of the antiferroelectric liquid crystal and the applied voltage.

FIG. 8 is a timing chart of each signal in the row drive circuit 26.

FIG. 9 is a partially enlarged view of row electrodes and column electrodes.

FIG. 10 is a diagram for explaining each voltage signal waveform applied between the electrodes of the liquid crystal panel.

FIG. 11 is a diagram showing a drive voltage waveform applied to a pixel in an ON state and a light transmittance of the pixel when the drive voltage waveform is applied.

FIG. 12 is a diagram showing a drive voltage waveform applied to a pixel in an OFF state and a light transmittance of the pixel when the drive voltage waveform is applied.

FIG. 13 is a characteristic diagram showing the relationship between the temperature and the contrast ratio when the scanning signal voltage is changed during the preliminary selection period.

FIG. 14 is a characteristic diagram showing a relationship between a temperature and a drive signal when the scanning signal voltage is changed in the preliminary selection period.

FIG. 15 is a waveform diagram showing a modified example in which the scanning signal voltage is modified.

FIG. 16 is a waveform diagram showing another modification in which the scanning signal voltage is modified.

FIG. 17 is a waveform diagram showing another modification in which the scanning signal voltage is modified.

FIG. 18 is a waveform diagram showing another modification in which the scanning signal voltage is modified.

FIG. 19 is a waveform diagram showing another modification in which the scanning signal voltage is modified.

FIG. 20 is a waveform diagram showing another modification in which the scanning signal voltage is modified.

FIG. 21 is a waveform diagram showing another modification in which the scanning signal voltage is modified.

FIG. 22 is a waveform diagram showing a modified example in which the column drive signal waveform is changed.

FIG. 23 is a waveform diagram showing another modification in which the column drive signal waveform is changed.

FIG. 24 is a waveform diagram showing another modification in which the column drive signal waveform is changed.

FIG. 25 is a waveform diagram showing another modification in which the column drive signal waveform is changed.

FIG. 26 is an overall view showing a configuration of a second embodiment of a matrix type liquid crystal display device according to the present invention.

27 is a circuit configuration diagram of a temperature correction control circuit in FIG.

28 is a flowchart showing the operation of the microcomputer shown in FIG.

FIG. 29 is a diagram showing temperature compensation table data.

FIG. 30 is a configuration diagram showing a specific circuit of row drive circuit 26 in FIG. 26.

FIG. 31 is a waveform diagram showing a scan signal voltage according to the second embodiment.

32 is a main part flowchart showing a modification of the flowchart in FIG. 28. FIG.

FIG. 33 is an overall diagram showing a configuration of a third exemplary embodiment of the present invention.

34 is a block diagram showing the image determination signal output circuit of FIG. 33 and an input / output waveform diagram of its main circuit.

FIG. 35 is a graph showing the relationship between the response time of an antiferroelectric liquid crystal and the holding voltage with the presence or absence of drag.

FIG. 36 is a graph showing the relationship between the light transmittance of antiferroelectric liquid crystal and the column driving voltage, with the holding voltage as a parameter.

FIG. 37 is a waveform diagram showing voltage waveforms of a conventional scanning signal and column driving signal.

FIG. 38 is a characteristic diagram showing the relationship between the voltage applied between electrodes and the ultimate transmittance.

[Explanation of symbols]

1 ... Liquid crystal panel, 2 and 2A ... Control device 11,
12 ... Electrode substrate, 13 ... Smectic liquid crystal, 2
4 ... control circuit, 25 ... column drive circuit, 2
6 ... Row drive circuit, 30c ... Power supply circuit, 30d ...
..Holding voltage switching circuit, G _1,1 , G _1,2 , ...
G _{m, n} ... Pixel, X ₁ , X ₂ , ..., X _m ... Column electrode, Y ₁ , Y ₂ , ..., Y _n ... Row electrode.

Claims (10)

[Claims] 1. The n row electrodes (Y ₁ , Y ₂ , ..., Y)
_n ) forming a first electrode substrate (11) and the first electrode substrate (11).
M rows of electrodes are arranged in parallel on the electrode substrate to form m × n pixels (G _1,1 , G _1,2 , ..., G _{m, n} ) in a matrix. Column electrodes (X ₁ , X ₂ , ...
.., X _m ) formed on the second electrode substrate (12),
A first electrode which is enclosed between the first and second electrode substrates and formed when no electric field is applied, when the electric field is applied in one direction, and when the electric field is applied in a direction opposite to the electric field; An anti-ferroelectric liquid crystal (13) having at least second and third stable states, the anti-ferroelectric liquid crystal (13) changing the light transmittance with respect to the electric field with a hysteresis characteristic. A liquid crystal panel (1) in which each pixel is turned off when the ferroelectric liquid crystal is in the first stable state, and in which each pixel is turned on when the antiferroelectric liquid crystal is in the second or third stable state. ), A first voltage for sequentially scanning each row electrode to turn each pixel into an OFF state, an ON state of each pixel, or an OF
Row driving means (26) for applying a second voltage for selecting the F state or a third voltage for holding the ON state or the OFF state of each of the selected pixels to each of the row electrodes as a row driving voltage. , Each pixel is turned on in synchronization with the scanning by the row driving means.
Column driving means (25) for applying a column driving voltage for driving the N state or the OFF state to each of the column electrodes, and controlling the row driving voltage and the column driving voltage based on image data to be displayed on the liquid crystal panel. In addition, in the liquid crystal display device, comprising: polarity changing means (24, 25) for changing the polarities of the row driving voltage and the column driving voltage each time the row driving means completes scanning of one screen of the liquid crystal panel. The row drive voltage is composed of a plurality of voltages that make the optical response of the antiferroelectric liquid crystal different, and the row drive voltage is changed to a plurality of voltages when the display image changes from a still image to a moving image. Of these, voltage switching means (30d, 40) for switching to a voltage having a high optical response of the antiferroelectric liquid crystal is provided, and the row driving means is switched by the voltage switching means. The matrix type liquid crystal display device, wherein the changed voltage is applied to each of the row electrodes as the row drive voltage. 2. The n row electrodes (Y ₁ , Y ₂ , ..., Y)
_n ) forming a first electrode substrate (11) and the first electrode substrate (11).
M rows of electrodes are arranged in parallel on the electrode substrate to form m × n pixels (G _1,1 , G _1,2 , ..., G _{m, n} ) in a matrix. Column electrodes (X ₁ , X ₂ , ...
.., X _m ) formed on the second electrode substrate (12),
A first electrode which is enclosed between the first and second electrode substrates and formed when no electric field is applied, when the electric field is applied in one direction, and when the electric field is applied in a direction opposite to the electric field; An anti-ferroelectric liquid crystal (13) having at least second and third stable states, the anti-ferroelectric liquid crystal (13) changing the light transmittance with respect to the electric field with a hysteresis characteristic. A liquid crystal panel (1) in which each pixel is turned off when the ferroelectric liquid crystal is in the first stable state, and in which each pixel is turned on when the antiferroelectric liquid crystal is in the second or third stable state. ), A first voltage for sequentially scanning each row electrode to turn each pixel into an OFF state, an ON state of each pixel, or an OF
Row driving means (26) for applying a second voltage for selecting the F state or a third voltage for holding the ON state or the OFF state of each of the selected pixels to each of the row electrodes as a row driving voltage. , Each pixel is turned on in synchronization with the scanning by the row driving means.
Column driving means (25) for applying a column driving voltage for driving the N state or the OFF state to each of the column electrodes, and controlling the row driving voltage and the column driving voltage based on image data to be displayed on the liquid crystal panel. In addition, in the liquid crystal display device, comprising: polarity changing means (24, 25) for changing the polarities of the row driving voltage and the column driving voltage each time the row driving means completes scanning of one screen of the liquid crystal panel. At least one of the second voltage and the third voltage is composed of a plurality of voltages that make the optical response of the antiferroelectric liquid crystal different, and when the displayed image changes from a still image to a moving image, Two
And a voltage switching means (30d, 40) for switching at least one of the third voltage to a voltage having a high optical response of the anti-ferroelectric liquid crystal among the plurality of voltages, and the row driving means has this voltage. A matrix type liquid crystal display device, wherein the voltage switched by the switching means is applied to each of the row electrodes as the row drive voltage. 3. The voltage switching means includes an image determining means (40) for determining whether or not the display image is a moving image based on an input video signal, and the voltage is determined when the image determining means determines the moving image. The matrix type liquid crystal display device according to claim 2, wherein the switching means switches the voltage. 4. The voltage switching means includes an image determination means (40) for determining whether or not a display image is a moving image based on an input video signal, and the voltage is determined when the image determination means determines the moving image. 3. The matrix type liquid crystal display device according to claim 2, wherein the switching means switches the voltage within a vertical blanking period specified by a vertical synchronizing signal. 5. The matrix type liquid crystal display device according to claim 3, wherein the image determination means determines that the image is a moving image when the number of screens is 1 frame per second or more based on the input video signal. 6. The voltage is set within a hysteresis characteristic region that represents the relationship between the light transmittance of the antiferroelectric liquid crystal and the voltage.
6. The matrix type liquid crystal display device according to any one of items 1 to 5. 7. The matrix type liquid crystal according to claim 6, wherein the plurality of voltages are set at voltages within a range of light transmittance of 10% to 90% within the hysteresis characteristic region. Display device. 8. A high optical response voltage, wherein the plurality of voltages exhibit an optical response higher than an optical response corresponding to a human afterimage viewing limit of the antiferroelectric liquid crystal, and the antiferroelectric voltage. 8. A low optical response voltage representing an optical response lower than an optical response corresponding to the human visual perception limit of the afterimage of the dielectric liquid crystal, and a low optical response voltage. One of the matrix type liquid crystal display devices. 9. The optical response corresponding to the afterimage visibility limit is 80 ± in optical response time of the antiferroelectric liquid crystal.
The matrix type liquid crystal display device according to claim 8, wherein the display time is 20 ms. 10. The matrix type liquid crystal display device according to claim 8, wherein the high optical response voltage is lower than the low optical response voltage.