JP2000321555A - Antiferroelectric liquid crystal display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain good display quality without causing a trailing phenomenon in an image by generating a black display after an image is displayed in pixels and until the next image is displayed. SOLUTION: A pair of polarizing plates and an antiferroelectric liquid crystal panel are disposed in such a manner that the polarizing axis of one of the polarizing plates almost coincides with the average direction of the major axes of the antiferroelectrtic liquid crystal molecules when no voltage is applied. One scanning period includes a selecting period to determine the state of the antiferroelectric liquid crystal and a nonselecting period to maintain the state determined in the selecting period. Before the scanning period is initiated, the whole pixels are reset into a first ferroelectrtic state or a second ferroelectric state, and a back light is not turned on in the period before scanning. By keeping the back light in a turn-off state during the reset period in the structure of the antiferroelectric liquid crystal panel equipped with the back light, the display is recognized as a back display even when the liquid crystal is changed into a transmission state and the trailing phenomenon of an image can be decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antiferroelectric liquid crystal display such as a liquid crystal display panel or a liquid crystal optical shutter array using an antiferroelectric liquid crystal as a liquid crystal layer.

[0002]

2. Description of the Related Art A liquid crystal panel using an antiferroelectric liquid crystal,
Japanese Patent Application Laid-Open No. 2 by Nippondenso Co., Ltd. and Showa Shell Sekiyu KK
Since 173724 reports that it has a wide viewing angle, that high-speed response is possible, and that multiplex characteristics are good, intensive studies have been made.

FIG. 2 is an example of a configuration diagram of an antiferroelectric liquid crystal panel when an antiferroelectric liquid crystal is used as a display. Between the polarizers 21a and 21b whose polarization axis directions are substantially perpendicular (crossed Nicols), the polarization axis of one of the polarizers and the average major axis of the antiferroelectric liquid crystal molecules when no voltage is applied. The liquid crystal cell 22 is set so that the directions are parallel to each other.
Is placed. FIG. 3 shows an antiferroelectric liquid crystal display in which a backlight is provided below the antiferroelectric liquid crystal panel. In the installation configuration of the polarizing plate as shown in FIG. 2, the antiferroelectric liquid crystal assumes an antiferroelectric state when no voltage is applied, does not transmit light, and the antiferroelectric liquid crystal panel displays black (non-transmissive state). Become. Also, depending on the polarity of the applied voltage, the antiferroelectric liquid crystal enters the first or second ferroelectric state, and the antiferroelectric liquid crystal molecules are inclined at a certain angle with respect to the polarization axis. And a white display (transmissive state) can be obtained.

FIG. 4 shows the relationship between the value of the applied voltage applied to the antiferroelectric liquid crystal panel and the transmittance of the antiferroelectric liquid crystal panel. As shown in FIG. 4, the anti-ferroelectric liquid crystal has an anti-ferroelectric state in which light does not pass, a first ferroelectric state in which light transmits when a positive voltage of a certain value or more is applied, and a certain value or more. And a second ferroelectric state in which light is transmitted when a negative voltage is applied.

FIG. 7 shows a typical method of driving an antiferroelectric liquid crystal display using the antiferroelectric liquid crystal panel having the polarizing plate structure shown in FIG. A selection period (Se) for selecting a display state within one scanning period and a non-selection period (NSe) for holding the selected display state are set, and depending on the display state, the next display is written. Instead, the reset period (Rs) for resetting the antiferroelectric liquid crystal to the antiferroelectric state is set before the start of the selection period. In FIG. 7, the ferroelectric state is reset during the reset period. However, a driving method for resetting to the ferroelectric state during the reset period is often used. Thus, in the driving method of the antiferroelectric liquid crystal display,
In order to perform good display, regardless of the previous display state,
It is common practice to always set a reset period for resetting to a predetermined ferroelectric state or antiferroelectric state.

[0006]

Conventionally, in a liquid crystal display using a general liquid crystal such as a nematic, when an image whose screen changes rapidly is projected, an image corresponding to the screen change can be accurately displayed. An impossible phenomenon was seen. For example, when a moving image of a ball is displayed on a liquid crystal display in a game or the like, a phenomenon in which the outline of the ball is not accurately projected and the outline is blurred (hereinafter, this phenomenon is referred to as a tailing phenomenon) ). Conventionally, it has been considered that this tailing phenomenon occurs due to the slow switching of liquid crystal molecules. However, recently, it has been reported that not only the switching speed of liquid crystal molecules but also the driving method of the conventional liquid crystal has one factor. In other words, in the scanning period in which the display based on the display data is written to the pixel, the next display is written to the pixel without resetting the display before writing even once. It remains as an afterimage and causes a tailing phenomenon.

It has been considered that the antiferroelectric liquid crystal has a higher switching speed than other general liquid crystals, so that the tailing phenomenon hardly occurs. However, the reason that the antiferroelectric liquid crystal display hardly causes the tailing phenomenon is that, in addition to the characteristic of fast switching, the unique driving method, that is, the setting of the reset period described above reduces the tailing phenomenon. Recent studies have shown that this is one of the factors.

However, in the conventional research, it has not been clarified how the antiferroelectric liquid crystal is most effectively controlled during the reset period to reduce the tailing phenomenon. . Furthermore, there is a problem that the tailing phenomenon cannot be completely eliminated when a moving image whose display data changes rapidly one after another is displayed simply by setting the reset period.

Therefore, the present invention suggests a good configuration of an antiferroelectric liquid crystal display in a reset period in an antiferroelectric liquid crystal display using an antiferroelectric liquid crystal, and is suitable for displaying a moving image or a still image. The purpose of the present invention is to obtain an excellent display quality by setting an optimum reset period.

[0010]

To achieve the above object, the present invention uses the following means.

[0011] An antiferroelectric liquid crystal display comprising a pair of polarizing plates combined so that the directions of their polarization axes are substantially perpendicular to each other, and a backlight, wherein either one of the pair of polarizing plates is polarized. The pair of polarizers and the antiferroelectric liquid crystal panel are configured so that the axis and the average molecular long axis direction of the antiferroelectric liquid crystal when no voltage is applied substantially coincide with each other. Has a selection period for determining the state of the antiferroelectric liquid crystal, and a non-selection period for holding the state determined in the selection period. Before the start of the scanning period, all pixels are simultaneously in the first ferroelectric state or The state is reset to the second ferroelectric state, and the backlight is turned off during this period.

Alternatively, the angle direction which is に 対 し of the polarization axis direction of each polarizing plate almost coincides with the average molecular long axis direction of the antiferroelectric liquid crystal when no voltage is applied. A pair of polarizers and an antiferroelectric panel are formed, and all pixels are simultaneously reset to an antiferroelectric state before the scanning period starts, and the backlight is turned off during this period.

[0013] Further, a mechanism for adjusting the length of the reset period, a display data memory for storing a plurality of generated display data, and a mechanism for comparing the plurality of display data stored in the display data memory are provided. To

Here, the plurality of display data may be two or more continuous display data for the antiferroelectric liquid crystal display to perform display. A plurality of display data are compared, and if the amount of change in the display data is small, the reset period is shortened, and if the amount of change is large, the reset period is lengthened.

In particular, when the antiferroelectric liquid crystal display has a backlight, it is desirable that the mechanism for adjusting the brightness of the backlight and the mechanism for adjusting the length of the reset period are linked to each other. When the length of the reset period is increased, the brightness of the backlight is increased, and when the length of the reset period is reduced, the brightness of the backlight is decreased.

Further, when light is transmitted during the reset period, the backlight is turned off during the reset period. For example, when a pair of polarizing plates and an anti-ferroelectric liquid crystal panel are configured such that any one of the polarizing axis directions of each polarizing plate and the average molecular long axis direction when no voltage is applied substantially match. Resets the antiferroelectric liquid crystal to the first ferroelectric state or the second ferroelectric state during the reset period, and turns off the backlight at that time.

Alternatively, for each polarization axis direction,
When a pair of polarizing plates and an antiferroelectric panel are configured such that the angle direction that is １ ／ and the average molecular long axis direction of the antiferroelectric liquid crystal when no voltage is applied substantially coincide with each other. First, the antiferroelectric liquid crystal in the reset period is set to the antiferroelectric state, and the backlight at that time is set to the non-lighting state.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventor has described how it is most effective to control an antiferroelectric liquid crystal during a reset period.
Various studies were made. As a result, when the display data switches,
That is, it has been clarified that the tailing phenomenon is reduced by performing black display during the next display after the display is performed by the pixel. That is, the reset period set before the start of the above-described scanning period needs to be set to black display (non-transmissive state). For example, even if the reset period exists, if the reset period is set to white display during the reset period, It was confirmed that the effect of reducing the tailing phenomenon was not obtained so much.

As described above, the relationship between the state of the antiferroelectric liquid crystal and the transmittance changes depending on the configuration of the polarizing plate of the antiferroelectric liquid crystal panel. As shown in FIG. 2, the polarization axis of one of the polarizers and the average major axis direction of the molecule in the absence of an electric field are:
When the liquid crystal cells are set to be parallel, as shown in FIG. 4, the antiferroelectric liquid crystal displays black (non-transmissive state) when in the antiferroelectric state, and white when in the first or second ferroelectric state. Display (transmissive state). With such a polarizing plate configuration,
When the driving method as shown in FIG. 7 is adopted, the reset period (R
In s), a voltage equal to or lower than the threshold is applied, the antiferroelectric liquid crystal enters an antiferroelectric state, and a black display (non-transmission state).
Therefore, in such a polarizing plate installation configuration, the tailing phenomenon can be reduced by setting the antiferroelectric liquid crystal in the antiferroelectric state during the reset period.

In the reset period (Rs), a voltage equal to or higher than the threshold value is applied, and the anti-ferroelectric liquid crystal is first or second.
It is also possible to adopt a driving method of resetting to the ferroelectric state. However, when the antiferroelectric liquid crystal is reset to the ferroelectric state, white display (transmissive state) occurs during the reset period, and the tailing phenomenon cannot be reduced. Therefore,
An antiferroelectric liquid crystal display having a configuration in which a backlight is provided on an antiferroelectric liquid crystal panel as shown in FIG. 3 is used, and the backlight is turned off during the reset period. By doing so, even if the antiferroelectric liquid crystal takes the first or second ferroelectric state during the reset period and enters the transmissive state, the display is recognized as a black display instead of a white display,
The same effect as in the case where the anti-ferroelectric liquid crystal is changed to the anti-ferroelectric state in the non-transmission state during the reset period is obtained.

Alternatively, as shown in FIG. 5, the angle direction which is 1/2 with respect to the polarization axis direction of each polarizing plate and the average molecular long axis direction of the antiferroelectric liquid crystal when no voltage is applied are shown. It is also possible to set the liquid crystal cells so that they substantially match. When the polarizing plate is installed in this manner, white display (transmission state) occurs when the antiferroelectric liquid crystal is in the antiferroelectric state,
Black display (non-transmissive state) is performed in the first or second ferroelectric state. The relationship between the transmittance and the applied voltage is as shown in FIG. When a driving method for a ferroelectric liquid crystal display as shown in FIG. 11 is employed in such a polarizing plate configuration, a voltage equal to or higher than a threshold is applied in the reset period (Rs), and the first or second antiferroelectric liquid crystal is applied. 2 and a black display (non-transmissive state). Therefore, the tailing phenomenon can be reduced by setting the antiferroelectric liquid crystal in the first or second ferroelectric state during the reset period.

In the reset period (Rs), a drive method of applying a voltage equal to or less than a threshold value to reset the antiferroelectric liquid crystal to the antiferroelectric state can be adopted. However, in that case, white display (transparent state) during the reset period
And the tailing phenomenon cannot be reduced. Therefore, using an antiferroelectric liquid crystal display as shown in FIG. 3 having a configuration in which an antiferroelectric liquid crystal panel is provided with a backlight,
The backlight is turned off during the reset period. By doing so, even if the antiferroelectric liquid crystal takes the antiferroelectric state during the reset period and enters the transmissive state, the display is recognized as black display instead of white display, and the tailing phenomenon is reduced. With this setting, the same effect as in the non-transmissive state in which the antiferroelectric liquid crystal is changed to the first or second ferroelectric state in the reset period can be obtained.

Further, it has been found that setting the reset period for black display to be sufficiently long is more effective in reducing the tailing phenomenon. In particular, when the display is switched quickly as in a game, the tailing phenomenon appears remarkably. In that case, by setting the reset period of black display to be long, the tailing phenomenon is reduced, and more preferable results are obtained. On the other hand, when the display switching is slow like a still image, even if the black display reset period is shortened,
The tailing phenomenon can be sufficiently eliminated.

However, if the reset period of the black display is lengthened, the tailing phenomenon is reduced, but the brightness of the entire display is darkened, and a problem arises in that it is impossible to obtain good display quality. Therefore, the length of the reset period is adjusted according to the displayed image, and the luminance of the backlight is adjusted according to the length of the reset period. For example, if the reset period is long, the entire display becomes dark, so the brightness of the backlight provided should be set high, and if the reset period is short, the brightness of the backlight should not be raised or set low. Good.
By providing a mechanism for adjusting the brightness of the backlight in this manner, even if the reset period changes, the brightness of the screen does not significantly change, and optimum display quality can always be obtained.

[0025]

(Embodiment 1) An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 8 is a panel configuration diagram of the antiferroelectric liquid crystal panel used in the first embodiment. The liquid crystal panel used in this embodiment is composed of a pair of glass substrates 83a and 83b having an antiferroelectric liquid crystal layer 82 having a thickness of about 1.7μ. Electrodes 84a and 84b are provided on the opposite surface of the glass substrate.
Are formed, and the polymer alignment films 85a, 85a are formed thereon.
b has been applied and a rubbing treatment has been performed. Further, a first polarizing plate 81a is provided outside one of the glass substrates so that a polarizing axis of the polarizing plate and an average molecular axis direction of liquid crystal molecules when no voltage is applied are parallel. The polarization axis of the second polarizing plate 81b is outside the glass substrate of the first type.
The second polarizing plate 81b is provided so that the direction of the polarization axis of the polarizing plate 81a is different from that of the polarizing plate 81a by 90 °.

FIG. 1 is a block diagram of the antiferroelectric liquid crystal display used in the present invention. The antiferroelectric liquid crystal display of the present invention includes a display data generation circuit 11, a drive voltage waveform control circuit 12, a scanning side voltage waveform generation circuit 14, a signal side voltage waveform generation circuit 13, a reset period adjusting volume 15, a backlight control. Circuit 16 and power supply circuit 17
It is composed of As a mechanism for adjusting the length of the reset period, the length of the reset period can be adjusted by using the reset period adjusting volume 15, and the brightness of the backlight is changed by the backlight control circuit.

FIG. 7 shows a driving method used as a conventional technique, but can be used in the present invention. As shown in FIG. 7, a change in the amount of light passing through the liquid crystal panel according to the voltage waveform (hereinafter referred to as a change in the amount of transmitted light) is shown.
(White display) and OFF (black display). The drive waveform in FIG. 7 is composed of two scanning periods in order to execute a display based on one display data, and the polarity of the voltage waveform in each scanning period is symmetric with respect to 0V.
Each scanning period includes a selection period (Se) for determining the display state based on the display data of the pixel and a non-selection period (NSe) for maintaining the state determined in the selection period (Se). And a reset period (Rs) for resetting to an arbitrary state without depending on the display state before the start of the scanning period. Since the polarizing plate is provided as shown in FIG. 2, if the combined voltage applied to the pixels during the reset period is equal to or less than the threshold, the antiferroelectric liquid crystal is always in the antiferroelectric state regardless of the display data, and the black display is not obtained. I was able to do it.

In the first scanning period of the scanning voltage waveform, a voltage of 0 V is applied to the first phase of the selection period, a voltage of 20 V is applied to the second phase, and a voltage of 8 V is applied to the non-selection period. A voltage of 0 V was applied during the reset period. Further, a voltage of 0 V is applied to the first phase of the selection period in the second scanning period, and a voltage of -20 V is applied to the second phase,
A voltage of -8 V was applied during the non-selection period, and a voltage of 0 V was applied during the reset period. A voltage of ± 5 V was applied from the signal side voltage waveform. The pulse width of each pulse was set to about 35 μs.

When the display data is ON (white display),
The second phase in the selection period of the composite voltage waveform exceeds the threshold value of the antiferroelectric liquid crystal and enters the first or second ferroelectric state, which is maintained in the non-selection period, and white display can be performed. When the display data is OFF (black display), since the black display is always displayed in the reset period regardless of the previous display state, a composite voltage equal to or lower than the threshold voltage is applied in the selection period.
The black display is maintained during the reset period.

A display based on the display data is performed, and in the next display, when the display data changes immediately, that is, in the case of a moving image display with a fast movement such as a game, a person observing the image display is used. The reset period can be extended by the reset period adjusting volume 15 shown in FIG. 1 while watching the state of the display image. Further, when the display data does not change as in a still image, that is, when the display is slow-moving, the reset period is shortened. As a result, no tailing phenomenon was observed in a moving image in which the display based on the display data changes one after another or in a still image in which the display hardly changes.

Further, a display data memory is provided so that a plurality of display data can be stored. FIG. 13 shows a circuit configuration in this case. This circuit includes a display data generation circuit, a display data memory 1, a display data memory 2, and a display data comparison circuit as a mechanism for comparing display data. The display data memories 1 and 2 store display data of continuous screens, and the two stored display data are compared by a display data comparison circuit. If the amount of change in the compared data is very large, it is determined that a fast-moving image is displayed. If the amount of change in the compared data is small or zero, a slow-moving still image is displayed. The result is input to the drive voltage waveform control circuit. When the amount of change in the compared data is large, the reset period is automatically lengthened by the reset period adjusting volume 15, and when the amount of change is zero or almost zero, the reset period is automatically shortened. Such a mechanism was adopted.

The display data memory 1 and the display data memory 2 may be continuous image data, or may be an appropriate plurality of screens such as every two images or every three images. In this embodiment, the number of the display data memories is two, but the number of the display data memories may be more.

As described above, the display data memory is provided,
By interlocking with the mechanism that adjusts the length of the reset period, the length of the reset period can be automatically adjusted even if the device incorporates an antiferroelectric liquid crystal display as part of a large device. It is possible to automatically maintain a good display state with less maintenance.

FIG. 9 is a diagram showing the relationship between the length of the reset period and the luminance of the backlight. As shown in this figure, the reset period adjusting volume and the backlight control circuit are set such that the backlight brightness is increased when the reset period is lengthened, and the backlight brightness is reduced when the reset period is shortened. By such adjustment, even if the reset period of the black display is long, the display was sufficiently bright and good display quality was obtained.

Embodiment 2 Hereinafter, a second embodiment of the present invention will be described in detail with reference to the drawings. In the second embodiment, as in the first embodiment, the circuit configuration is as shown in FIG. 1, and the configuration of the panel is also the configuration shown in FIG. The configuration of the polarizing plate is also the same as that of the first embodiment shown in FIG. 2, and as shown in FIG. 4, the non-transmissive state in the antiferroelectric state and the transmissive state in the first or second ferroelectric state. I made it. In this embodiment, as shown in FIG. 3, a backlight is provided below the liquid crystal display.

In the first embodiment, during the reset period, the antiferroelectric liquid crystal is reset to the antiferroelectric state to display black.
In Example 2, the antiferroelectric liquid crystal was reset to the first or second ferroelectric state during the reset period. FIG. 10 is a diagram showing the driving waveform used in this embodiment, and the display data is ON.
(White display) and the drive waveform and its transmittance when OFF (black display). Y1, Y2, Y
3 denotes a composite voltage waveform applied to the pixel, and T1 and T
2 and T3 indicate the transmittances of Y1, Y2 and Y3, respectively. The scanning-side voltage waveform is composed of two scanning periods in order to execute display based on one display data, and the polarity of the voltage waveform in each scanning period is symmetric with respect to 0V. Each scanning period includes a selection period (Se) for determining a display state based on display data of a pixel, and a non-selection period (NSe) for maintaining the state determined in the selection period (Se). Before the start of this one scanning period, a reset period (R) for simultaneously resetting all the pixels to the ferroelectric state is set.
s) is provided. Since all the pixels are reset at the same time, if the application order of the scanning electrodes is later, the period of the reset state becomes longer correspondingly, and the period of the pixel of Y3 is in the first or second ferroelectric state than the pixel of Y1. Becomes longer.

In the scanning-side voltage waveform, a voltage of 20 V is applied in a reset period set before the start of the first scanning period, and in a reset period before the start of the second scanning period,
A voltage of -20 V was applied. A voltage of 0 V is applied to the first phase of the selection period of the first scanning period in the scanning-side voltage waveform.
A voltage of -10 V is applied to the second phase, a voltage of 8 V is applied during the non-selection period, and a voltage of 0 V is applied to the first phase of the selection period of the second scanning period in the scanning voltage waveform. A voltage of 10 V is applied to the second phase, and -8 during the non-selection period.
A voltage of V was applied. ± 5 V from signal side voltage waveform
And the pulse width was about 35 μs. Further, Y1 to Y3 in FIG. 10 do not show the scanning-side voltage waveform, but show the waveform of the composite voltage of the scanning-side voltage and the signal-side voltage.

Since the antiferroelectric liquid crystal is in the first or second ferroelectric state during the reset period, a large voltage having a polarity opposite to that of the reset period is used to bring the display data into the antiferroelectric state when the display data is black. Is applied. Even if a voltage having a large reverse polarity is applied, the antiferroelectric liquid crystal does not change to the ferroelectric state but switches to the antiferroelectric state because the application period is sufficiently short. This is maintained even during the non-selection period, and black display is performed. When the display data is white display, if a voltage value that does not switch to the antiferroelectric state is applied in the selection period, the first or second ferroelectric state in the reset period becomes
It is held during the selection period and the non-selection period, and white display can be performed.

Here, as shown in FIG. 10, regardless of the previous display state, the first state of the transmission state is always in the reset period.
Alternatively, the second ferroelectric state is set. At this time, the backlight is turned off in synchronization with the reset period. Therefore, although the reset period is in the transmission state, it is recognized as a black display, and the tailing phenomenon is reduced. The length of the reset ferroelectric state period varies depending on the pixel, but the non-lighting state period is the reset period in the pixel which is the shortest in the ferroelectric state reset period, as indicated by Y1 in FIG. According to the length.

Further, similarly to the first embodiment, the length of the reset period can be adjusted with the reset period adjusting volume while watching the state of the display image, and even a moving image in which the display based on the display data changes one after another. No tailing phenomenon was observed even with a still image that hardly changed. Further, similarly to the first embodiment, a display data memory is provided,
The length of the reset period can be automatically changed by linking with a mechanism that adjusts the length of the reset period.

Similarly to the first embodiment, the reset period adjusting volume and the backlight control circuit are set so that the backlight brightness is increased when the reset period is lengthened, and the backlight brightness is decreased when the reset period is shortened. did. By such adjustment, even if the reset period of the black display is long, the display was sufficiently bright and good display quality was obtained.

(Embodiment 3) Hereinafter, a third embodiment of the present invention will be described in detail with reference to the drawings. In the third embodiment, the first embodiment
Similarly, the circuit configuration was as shown in FIG. 1, and the configuration of the panel was also as shown in FIG. However, as for the configuration of the polarizing plate, as shown in FIG. 5, the polarizing axes of the polarizing plate were configured to be substantially perpendicular to each other, and the average molecular axis direction of the antiferroelectric liquid crystal molecules when no voltage was applied was changed. The polarizers were installed so as to be substantially parallel to a direction that was １ ／ of the angle formed by the polarization axes of the respective polarizing plates. When the polarizing plate is installed in this manner, the relationship between the applied voltage and the transmittance as shown in FIG. 6 is shown, and the anti-ferroelectric state becomes a transmission state, and the first or second ferroelectric state becomes a non-transmission state. In this embodiment, as shown in FIG. 3, a backlight is provided below the liquid crystal display.

FIG. 11 is a diagram showing driving waveforms used in the present embodiment, and shows a change in the amount of transmitted light of the liquid crystal panel according to the voltage waveform, in the case of ON (white display) and OFF (black display). . This drive waveform is composed of two scanning periods in order to execute display based on one display data, and the polarity of the voltage waveform in each scanning period is symmetric with respect to 0V. In addition, each scanning period is a selection period (S) for determining a display state based on display data of a pixel.
e) and a non-selection period (NSe) for maintaining the state determined in the selection period (Se). The reset period (Rs) for always resetting to an arbitrary state without depending on the display state is scanned. It is configured to be set before the start of the period. In the present embodiment, the scanning-side voltage waveform is set to ± 20 V in the reset period, the combined voltage applied to the pixels in the reset period is equal to or higher than the threshold, and the first or second ferroelectric state is always taken regardless of the display state. Black display was always performed during the reset period.

In the first scanning period of the scanning-side voltage waveform, a voltage of 0 V is applied to the first phase of the selection period (Se), a voltage of -10 V is applied to the second phase, and a voltage of -10 V is applied to the non-selection period (NSe). Applied a voltage of 8V. During the reset period (Rs) before the second scanning period, a voltage of −20 V was applied. In the scanning-side voltage waveform, a voltage of 0 V is applied to the first phase in the selection period of the second scanning period, and 10 V is applied to the second phase.
And a voltage of -8 V was applied during the non-selection period. In the reset period before the first scanning period, 20
A voltage of V was applied. From the signal side voltage waveform, ± 5
A voltage of V was applied. The pulse width of each pulse is about 3
It was set to 5 μs.

Since the ferroelectric state is shown during the reset period and black display is performed, the state of the reset period may be maintained as it is when the display data is OFF (black display). That is, a combined voltage waveform that does not cause the antiferroelectric liquid crystal to transition to the antiferroelectric state is applied during the selection period, and black display is performed. When the display data is ON (white display), the composite voltage of the second phase in the selection period applies a voltage having a polarity opposite to the voltage applied in the reset period. Although the voltage has a large reverse polarity, the antiferroelectric liquid crystal does not change to the ferroelectric state opposite to the ferroelectric state selected in the reset period, enters the antiferroelectric state, and is maintained in the non-selective period. White display can be performed.

Further, similarly to the first embodiment, the length of the reset period can be adjusted with the reset period adjusting volume while watching the state of the displayed image. Therefore, no tailing phenomenon was observed in a moving image in which the display based on the display data changes one after another or in a still image in which the display hardly changes. Further, similarly to the first embodiment, a display data memory is provided, and the length of the reset period is automatically changed by linking with a mechanism for adjusting the length of the reset period.

As in the first embodiment, the reset period adjusting volume and the backlight control circuit are set so that the brightness of the backlight is increased when the reset period is long and the brightness of the backlight is decreased when the reset period is short. did. By such adjustment, even if the reset period of the black display is long, the display was sufficiently bright and good display quality was obtained.

(Embodiment 4) Hereinafter, a fourth embodiment of the present invention will be described in detail with reference to the drawings. In the fourth embodiment, the third embodiment
Similarly, the circuit configuration was as shown in FIG. 1, and the configuration of the panel was also as shown in FIG. The installation configuration of the polarizing plate is also the same as that of the third embodiment shown in FIG. 5, and as shown in FIG. 6, the transmission state is set in the antiferroelectric state, and the non-transmission state is set in the first or second ferroelectric state. I made it. In this embodiment, as shown in FIG. 3, a backlight is provided below the liquid crystal display.

In the third embodiment, during the reset period, the antiferroelectric liquid crystal is reset to the first or second ferroelectric state to display black. In the fourth embodiment, the antiferroelectric liquid crystal is reset during the reset period. Reset to antiferroelectric state. FIG. 12 is a diagram showing the driving waveform used in the present embodiment, and shows, as an example, a case where the display data is OFF (black display) and a case where the display data is ON (white display). Y1, Y2, and Y3 indicate the combined voltage waveform applied to each pixel, and T1, T2, and T3 indicate the transmitted light amounts (transmittance) of Y1, Y2, and Y3, respectively. The scanning-side voltage waveform is composed of two scanning periods in order to execute display based on one display data, and the polarity of the voltage waveform in each scanning period is symmetric with respect to 0V. Each scanning period includes a selection period (Se) for determining a display state based on display data of a pixel, and a non-selection period (NSe) for maintaining the state determined in the selection period (Se). Before the start of one or both scanning periods, a reset period (Rs) is provided for simultaneously resetting all pixels to the antiferroelectric state.

In the scanning-side voltage waveform, a voltage of 0 V is applied to the first phase of the selection period of the first scanning period, a voltage of 20 V is applied to the second phase, and a voltage of 8 V is applied to the non-selection period. In addition, a voltage of 0 V is applied to the first phase of the selection period of the second scanning period in the scanning-side voltage waveform, a voltage of -20 V is applied to the second phase, and a voltage of -8 V is applied to the non-selection period. Was applied. A voltage of ± 5 V was applied from the signal side voltage waveform, and each pulse width was about 35 μs. In FIG. 12, Y1 to Y3 show combined voltage waveforms obtained by combining the scanning side voltage and the signal side voltage.

Since the antiferroelectric liquid crystal is in the antiferroelectric state during the reset period, white display is performed, and the display data is
In the case of FF (black display), in order to shift to the first or second ferroelectric state, a voltage value sufficiently larger than the threshold voltage is applied to the pixel to switch to the first or second ferroelectric state. This is maintained even during the non-selection period, and black display is performed. In the case where the display data is white display, if a voltage value or 0 V that does not switch to the ferroelectric state is applied during the selection period, the antiferroelectric state of the reset period is maintained during the selection period and the non-selection period, and the white display is performed. It can be performed.

Here, as shown in FIG. 12, the antiferroelectric state of the transmission state is always set in the reset period regardless of the previous display state. At this time, the backlight is turned off in synchronization with the reset period. And Therefore, although the reset period is in the transmission state, it is recognized as a black display, and the tailing phenomenon is reduced. The period of the non-lighting state is set to the length of the reset period of Y1, which is the shortest period of the reset state.

Further, similarly to the first embodiment, the length of the reset period can be adjusted with the reset period adjusting volume while observing the state of the display image. Therefore, no tailing phenomenon was observed in a moving image in which the display based on the display data changes one after another or in a still image in which the display hardly changes. Further, similarly to the first embodiment, the display data memory is provided, and the length of the reset period can be automatically changed by linking with a mechanism for adjusting the length of the reset period.

Similarly to the first embodiment, the reset period adjusting volume and the backlight control circuit are set so that the brightness of the backlight is increased when the reset period is long and the brightness of the backlight is decreased when the reset period is short. did. By such adjustment, even if the reset period of the black display is long, the display was sufficiently bright and good display quality was obtained.

Here, in the driving method adopted in the first to fourth embodiments, in order to execute one display data, one scanning frame has one frame and two scanning periods having symmetric polarities in one frame. The reset period was set before the start of each scanning period. However, the reset period need not be twice in one frame as described above, and may be only once before the start of the first scanning period.

[0056]

According to the antiferroelectric liquid crystal display of the present invention, a good display quality without tailing phenomenon can be obtained by employing a driving method according to the arrangement of the polarizing plate. Further, even when a slow-moving display such as a still image is performed or a fast-moving display such as a game is performed, a favorable display with a constant luminance can be performed.

[Brief description of the drawings]

FIG. 1 is a block diagram of an antiferroelectric liquid crystal display used in the present invention.

FIG. 2 is a configuration diagram of an antiferroelectric liquid crystal panel and a polarizing plate used in the present invention.

FIG. 3 is a configuration diagram of an antiferroelectric liquid crystal display and a backlight used in the present invention.

FIG. 4 is a transmittance curve diagram of the antiferroelectric liquid crystal display used in the present invention.

FIG. 5 is a configuration diagram of an antiferroelectric liquid crystal panel and a polarizing plate used in the present invention.

FIG. 6 is a transmittance curve diagram of the antiferroelectric liquid crystal display used in the present invention.

FIG. 7 is a diagram showing driving waveforms of the antiferroelectric liquid crystal display used in the present invention.

FIG. 8 is a configuration diagram of an antiferroelectric liquid crystal panel used in the present invention.

FIG. 9 is a diagram showing the relationship between the reset period of the antiferroelectric liquid crystal display used in the present invention and the luminance of the backlight.

FIG. 10 is a diagram showing driving waveforms of the antiferroelectric liquid crystal display used in Example 2.

FIG. 11 is a diagram showing driving waveforms of the antiferroelectric liquid crystal display used in Example 3.

FIG. 12 is a diagram showing driving waveforms used for the antiferroelectric liquid crystal display used in Example 4.

FIG. 13 is a circuit configuration diagram for automatically checking the speed of motion of an image.

[Description of Signs] 81a, 81b Polarizer 82 Antiferroelectric Liquid Crystal 83a, 83b Glass Substrate 84a, 84b Electrode 85a, 85b Alignment Film 86 Backlight

Claims (9)

[Claims] 1. An antiferroelectric liquid crystal panel having an antiferroelectric liquid crystal sandwiched between a pair of substrates, a pair of polarizing plates combined so that their polarization axes are substantially perpendicular to each other, and a backlight. An anti-ferroelectric liquid crystal display comprising: a first ferroelectric liquid crystal and a second ferroelectric liquid crystal when a voltage having a polarity opposite to that of the first ferroelectric state is applied. State, showing an antiferroelectric state, so that the polarization axis direction of any of the polarizing plate and the average molecular long axis direction of the antiferroelectric liquid crystal when no voltage is applied substantially match,
A pair of polarizing plates and an antiferroelectric liquid crystal panel are configured, and the antiferroelectric liquid crystal display has at least one scanning period when executing display based on one display data, and The period has a selection period for determining the state of the antiferroelectric liquid crystal, and a non-selection period for maintaining the state determined by the selection period. And a reset period in which the anti-ferroelectric liquid crystal is in the first ferroelectric state or the second ferroelectric state, and the backlight is in a non-lighting state during the reset period. An antiferroelectric liquid crystal display characterized by the following. 2. An antiferroelectric liquid crystal panel having an antiferroelectric liquid crystal sandwiched between a pair of substrates, a pair of polarizing plates combined so that their polarization axes are substantially perpendicular to each other, and a backlight. An anti-ferroelectric liquid crystal display comprising: a first ferroelectric liquid crystal and a second ferroelectric liquid crystal when a voltage having a polarity opposite to that of the first ferroelectric state is applied. State and antiferroelectric state, wherein the angle direction becomes 1/2 with respect to the polarization axis direction of each polarizing plate, and the average molecular long axis direction of the antiferroelectric liquid crystal when no voltage is applied. And a pair of polarizers and an anti-ferroelectric panel are configured so as to substantially match with each other. When the anti-ferroelectric liquid crystal display executes one display data, at least one scanning period is required. The scanning period is selected to determine the state of the antiferroelectric liquid crystal. And a non-selection period for holding the state determined by the selection period, and a reset period for simultaneously resetting the antiferroelectric liquid crystal to an arbitrary state in all pixels before the start of the scanning period. And an antiferroelectric liquid crystal display wherein the antiferroelectric liquid crystal is in an antiferroelectric state during a reset period and the backlight is in a non-lighting state. 3. An antiferroelectric liquid crystal display in which antiferroelectric liquid crystal is sandwiched between a pair of substrates, wherein the ferroelectric liquid crystal display performs display based on one display data. Has at least one scanning period, and before the scanning period starts, has a reset period for resetting the antiferroelectric liquid crystal to an arbitrary state, and the antiferroelectric liquid crystal display has a reset period length. An adjusting mechanism;
An antiferroelectric liquid crystal display comprising: a display data memory for storing a plurality of generated display data; and a mechanism for comparing the plurality of display data stored in the display data memory. 4. The anti-ferroelectric liquid crystal according to claim 3, wherein the plurality of display data are two or more display data obtained by the anti-ferroelectric liquid crystal display continuously displaying. display. 5. A method of comparing a plurality of display data and adjusting the reset period to be shorter when the amount of change in the display data is small, and to be longer when the amount of change is large. 5. The antiferroelectric liquid crystal display according to claim 3, which is capable of being used. 6. The antiferroelectric liquid crystal display includes a backlight, and a mechanism for adjusting the brightness of the backlight and a mechanism for adjusting the length of the reset period are interlocked. 6. The antiferroelectric liquid crystal display according to 3 to 5. 7. The backlight according to claim 6, wherein the longer the reset period, the higher the luminance of the backlight, and the shorter the reset period, the lower the luminance of the backlight. Ferroelectric liquid crystal display. 8. An antiferroelectric liquid crystal display has a pair of polarizing plates combined so that their polarization axis directions are substantially perpendicular to each other. The pair of polarizers and the antiferroelectric liquid crystal panel are configured so that the average molecular major axis direction of the antiferroelectric liquid crystal at the time of application substantially coincides with the first ferroelectric liquid crystal. A dielectric state, a second ferroelectric state when a voltage having a polarity opposite to that of the first ferroelectric state is applied, and an antiferroelectric state. In the reset period, the antiferroelectric liquid crystal of all pixels is 8. The anti-ferroelectric liquid crystal display according to claim 6, wherein the first ferroelectric state or the second ferroelectric state is at the same time, and the backlight is in a non-lighting state during the reset period. 9. An anti-ferroelectric liquid crystal display has a pair of polarizing plates combined so that their polarization axis directions are substantially perpendicular to each other.
The pair of polarizers and the antiferroelectric liquid crystal panel are configured so that the angle direction becomes substantially equal to the average molecular long axis direction of the antiferroelectric liquid crystal when no voltage is applied. The dielectric liquid crystal has a first ferroelectric state, a second ferroelectric state when a voltage having a polarity opposite to that of the first ferroelectric state is applied, and an antiferroelectric state. 8. The anti-ferroelectric liquid crystal display according to claim 6, wherein the anti-ferroelectric liquid crystal of all pixels is in an anti-ferroelectric state, and the backlight is in a non-lighting state during a reset period.