JPH029A - Method of driving liquid crystal light valve - Google Patents

Abstract

PURPOSE:To prevent the degradation in printing quality and to obtain good printing characteristics by impressing the voltage pulses for averting the change in the stable state of the arrangement obtd. by prescribed pulses in the period except the selection period of a liquid crystal. CONSTITUTION:The voltage pulse larger a positive saturation value +V2 t10 is impressed and the liquid crystal attains, for example, a bright state in the frame t12 where an ON is seleced. The voltage pulse (-V1-V2)t11 which is of the polarity reverse from the polarity of the above-mentioned voltage and has the absolute value larger than the negative saturation value is impressed and the dark state is attained in the non-selection period t11. The voltage pulse -V2t20 is impressed and the liquid crystal attains the dark state within the selection period t20 of the frame t22 of an OFF. Further, the voltage pulse larger than the negative saturation value is impressed and the OFF state is maintained in the non-selection period t21. The contrast of the ON and the OFF is, therefore, increased and the change in the printing shape is obviated.

Description

[Detailed description of the invention] [Industrial benefits field] The present invention relates to a method for driving a liquid crystal light valve.

In particular, it relates to a method for driving ferroelectric liquid crystals.

[Prior Art] In recent years, with the increase in the capacity and speed of information processing, and the popularization of OA equipment, printing devices, which are one of the terminal equipment for OA, are also becoming faster, with higher printing quality, and even lower printing quality. Price has become a necessity. As a printing device for this purpose, a printing device that uses a liquid crystal light valve as an optical signal generating section and applies electrophotographic technology is beginning to be put into practical use. Conventionally, the liquid crystal light valve of this printing device generally uses a method of driving a nematic liquid crystal in two cycles of low frequency and high frequency to make the liquid crystal molecules stand up or lie down, thereby controlling the intensity of transmitted light.

However, recently, attention has been focused on the high-speed response exhibited by ferroelectric liquid crystals,
JP-A-59-151910 proposes the use of a liquid crystal light valve capable of higher-speed printing in a printing device. As a method for driving this ferroelectric liquid crystal, the patent application
As shown in Japanese Patent Application No. 0-021499, Japanese Patent Application No. 60-147401, etc., the on or off state is selected depending on the polarity of the voltage pulse exceeding the threshold value, and when it is not selected, the memory property of the ferroelectric liquid crystal is In this driving method, when off, the liquid crystal light valve (shutter window) is closed (light blocking), and when on, the liquid crystal light valve is open (light transmission) regardless of whether it is selected or not.

[Problem to be solved by the invention] Therefore, when a liquid crystal light valve as a printing device is operated using the conventional ferroelectric liquid crystal driving method, due to the memory property of the ferroelectric liquid crystal, the selection period is Otherwise, the shutter window will be open, and when printing on paper, the first
As shown in FIG. 2, the printing pixels become longer in the sub-scanning direction (rotation direction of the photosensitive drum), resulting in a problem in that the resolution (print quality) in the sub-scanning direction decreases.

[Means for Solving the Problems] In order to solve the problems described above, the method for driving a liquid crystal light valve of the present invention has the purpose of changing at least the alignment direction of liquid crystal molecules within the selection period to the display content of pixels. Accordingly, a first voltage pulse whose absolute value is equal to or greater than the saturation value of the liquid crystal element is applied to align the bistable state to one of the bistable states, and In the second period, the absolute value of the bistable state to always align in one direction regardless of the display content of the pixels is greater than or equal to the saturation value of the element.
applying a voltage pulse of, and said first.

A special feature characterized in that during periods other than when the second voltage pulse is applied, voltage pulses are applied for not changing the stable state of the array obtained by the first and second voltage pulses, respectively. *Example] FIG. 1 is a schematic diagram showing a liquid crystal light valve in an example of the present invention. Figure 1 (α) is a plan view,
Figure (b) is a cross-sectional view. Transparent electrodes 13.14 made of indium oxide and tin oxide are provided on opposing surfaces of a pair of substrates 11.12 made of glass or plastic. Each of these electrodes is formed into a stripe shape, and the electrodes are arranged approximately perpendicularly to each other and combined. Here 15. i4 is a scanning electrode and a signal electrode, respectively, and an optical mask 15 made of nickel or the like is provided thereon except for a part of the micro shutter 10. Further, after providing an insulating layer 16 such as SiO□ thereon, an oblique evaporation film such as 810 or polyimide is formed to orient the liquid crystal.

An alignment layer 11117 made of nylon or the like is provided and rubbed to align the liquid crystal 1B. In addition, polarizing plates 19 are installed on the surfaces of the upper and lower substrates 11 and 12 where the electrodes 15 and 14 are not provided so that they are orthogonal to each other, and one polarization axis similar to the polarization is set to the bistable state of the ferroelectric liquid crystal. Matched one.

Note that the cell thickness of the liquid crystal element is approximately 1.5 to 3 μm.

(Example 1) FIG. 2 shows the driving waveform and optical response of the first example.

Using the element shown in Figure 1, the element gap thickness is 2.0.
/ J m, Liquid Crystal Hamelcksha il! ZLI-5489 was used.

FIG. 2 201 is a scanning electrode waveform, 2o2 is a signal electrode waveform,
205 is a waveform applied to the liquid crystal element, and 204 is an optical response of the liquid crystal element. The selection period t, - is displayed on the liquid crystal. ,
tl at t2°. is ON (temporarily bright state) s t2
For @, oyy (temporarily dark state) is selected. In the frame 111 in which ON is selected, during the selection period t1°, a voltage pulse +v2·tlo greater than the positive saturation value is applied, and the element enters a bright state. In the non-selection period 111, a voltage pulse (-v, ,
-v, )·t□ is applied, resulting in a dark state. 011'F
Regarding the frame t22 in which the selection period t2° is selected, the liquid crystal is supplied with a voltage pulse −v2 of a negative saturation value or higher during the selection period t2°.
t2° is applied, and the device enters a dark state. Further, during the selection period t21, a voltage pulse equal to or higher than the negative saturation value is applied, so that the OFF state is maintained. Therefore, in this example, good optical characteristics were obtained as shown at 204 in FIG. OBI, OIPF's Hun Trust Kako・t
12: T22 was 30:1 or more at 50° C., and the contrast ratio between different pixels was almost constant regardless of the display content.

In addition, since light is always blocked during the non-selection period, when the liquid crystal light valve of this example was incorporated into a printing device and operated using the driving method of this example, the print shape on paper did not change and good printing characteristics were obtained. was gotten. In this example, 1/
Although a two-day drive waveform is shown, the present invention is not limited to this, and the duty ratio can be arbitrarily selected within a range that can ensure the amount of light.

(Example 2) FIG. 3 shows the drive waveform and optical response of the second example.

The element shown in Figure 1 is used, and the element gap thickness is 2.0.
The liquid crystal used was ZB 3489 manufactured by Merck.

501 is a scanning electrode waveform, 302 is a signal electrode waveform,
303 is a waveform applied to the liquid crystal element, and 504 is an optical response of the liquid crystal element. The selection period t1゜, t
,. In t,. is ON (temporarily in bright state), t2° is o
yy (temporarily dark state) is selected. In the frame ttz in which ON is selected, during the selection period t8°, the first voltage pulse V whose absolute value is larger than the saturation voltage of the liquid crystal element
.

A voltage of 10 V is applied, and the device enters a bright state. Subsequently, a voltage pulse V! having an insulation value below the threshold voltage and having the same polarity as the first voltage pulse is applied. is applied to maintain the bright state. Next, the first
A fifth voltage pulse having a polarity opposite to that of the voltage pulse and having an absolute value equal to or higher than the saturation voltage is applied, resulting in a dark state. This is because only voltage pulses below the threshold voltage of the element are applied during the non-selection period.

Maintain darkness. On the other hand, the frame t where OFF is selected
For 2□, the selection period is t. Insulation value vIs
v! Subsequently, voltage pulses are applied, but since they are all below the threshold voltage of the liquid crystal element, the OFF
Select a state. Furthermore, a voltage pulse -■4 having a polarity opposite to that of the voltage pulse and having an absolute value equal to or higher than the saturation value is applied, and OF
Maintain IP state. During the non-selection period 111, only voltage pulses below the threshold voltage are applied, so that they do not affect the optical response of the liquid crystal. Therefore, in this example, the third
As shown at 304 in the figure, good optical characteristics were obtained. Oli, OFF's Huntrust Hiko・t□, :Ko・t
tz was 30:1 or more at 50° C., and the contrast ratio between different pixels was almost constant regardless of the display content.

In addition, since light is always blocked during the non-selection period, when the liquid crystal light valve of this example was incorporated into a printing device and operated using the driving method of this example, the print shape on paper did not change and good printing characteristics were obtained. was gotten. In this example, 1/
Although a two-day drive waveform is shown, the present invention is not limited to this, and the duty ratio can be arbitrarily selected within a range that can ensure the amount of light.

(Example 5) FIG. 4 shows the drive waveform and optical response of the third example.

The element shown in Figure 1 is used, and the element gap thickness is 2.0.
The μ island and the liquid crystal used were ZL-3774 manufactured by Merck & Co., Ltd.

4, 401 is a scanning electrode waveform, 402 is a signal electrode waveform,
403 is a waveform applied to the liquid crystal element, and 404 is an optical response of the liquid crystal element. The selection period t10rt is displayed on the LCD.
! . , tto is ON (temporarily bright state), tto is O
IPF (tentatively in dark state) is selected. In the frame 111 in which ON is selected, during the selection period t (1), a voltage pulse -vl-1-V4 of -1, which is larger in absolute value than the saturation voltage of the liquid crystal element, is marked 1, and the element enters a bright state.

Subsequently, a voltage pulse with an absolute value of 0 is applied, but the bright state is maintained due to the memory property unique to ferroelectric liquid crystals. Next, a third voltage pulse -Vi having a polarity opposite to that of the first voltage pulse and having an absolute value equal to or higher than the saturation voltage is applied, resulting in a dark state. During the non-selection period 111, a group of voltage pulses having the same polarity as the fifth voltage pulse and whose absolute value is greater than or equal to the saturation value of the element -vs tV2t-V1=-V, +V4=-V,
Since +V continues to be applied, the dark state is maintained. on the other hand,
For the frame 111 that selected the OFIF state, the selection period t. , a first voltage pulse -Vi whose absolute value is larger than the saturation voltage of the liquid crystal element is applied, and the OFF
Select a state. The OII'1 state is maintained by subsequently applying 8g2 and the fifth voltage pulses -Vi, -V. Furthermore, the non-selection period 111 is the non-selection period 11.
1, the voltage pulse group -y, -v whose absolute value is larger than the saturation voltage of the liquid crystal element, regardless of the pixel selection content.
,, -v1=-v.

Since -1--v4=-v, -1-v1, etc. are applied, the OFF state is maintained. Therefore, in this example, good optical characteristics were obtained as shown at 204 in FIG. Contrast specific gravity of ON, OIFF・tsz:I
-txt was 30:1 or more at 35°C, and the contrast ratio between different pixels was almost constant regardless of the display content.

In addition, since light is always blocked during the non-selection period, when the liquid crystal light valve of this example was incorporated into a printing device and operated using the driving method of this example, the print shape on paper did not change and good printing characteristics were obtained. was gotten. In this example, 1/
Although a three-duty drive waveform is shown, the present invention is not limited to this, and the duty ratio can be arbitrarily selected within a range that can ensure the amount of light.

(Example 4) FIG. 5 shows the driving waveform and optical response of the fourth example.

The element shown in Figure 1 is used, and the element gap thickness is 2.0.
The liquid crystal used was ZL-5774 manufactured by Merck & Co., Ltd.

5, 501 is a scanning electrode waveform, 502 is a signal electrode waveform,
503 is a waveform applied to the liquid crystal element, and 504 is an optical response of the liquid crystal element. The selection period tiOt is displayed on the LCD.
tll. tl is ON (temporarily in bright state), t.

oyy (temporarily dark state) is selected. In the frame 111 in which ON is selected, during the selection period t1o, the first voltage ((
Rouss V□+V is applied, and the device enters a bright state. Next, a second voltage pulse having a polarity opposite to that of the first voltage pulse and having an absolute value equal to or higher than the saturation voltage is applied, and the element enters a dark state. In the non-selection period 111, a group of voltage pulses -v, , -v1=-v, which have the same polarity as the second voltage pulse and whose absolute value is equal to or greater than the saturation value of the element.

+V is applied, so the dark state is maintained.

On the other hand, for the frame tzz in which oyy (dark state) is selected, a first voltage pulse -Vi whose absolute value is larger than the saturation voltage of the liquid crystal element is applied during the selection period t2° to select the OFF state. Subsequently, a second voltage pulse having the same polarity as the first voltage pulse and having an absolute value equal to or higher than the saturation voltage of the element is applied.
A voltage pulse -Vi is applied to maintain the dark state. Furthermore, the non-selection period 111. is the same as the non-selection period 111, and is a voltage pulse -Vi''-v2 whose absolute value is larger than the saturation voltage of the liquid crystal element, regardless of the pixel selection content.
+vSy-V is applied, so the oyy state (dark state) is maintained. Therefore, in this embodiment, 2 in FIG.
As shown in No. 04, good optical properties were obtained. ON
, the contrast specific gravity of OFF・ttz:I”tl2 is
30:1 or more at 35° C.: The contrast ratio between different pixels was almost constant regardless of the display content.

In addition, since light is always blocked during the non-selection period, when the liquid crystal light valve of this example was incorporated into a printing device and operated using the driving method of this example, the print shape on paper did not change and good printing characteristics were obtained. was gotten. In this example, 1/
Although a three-duty drive waveform is shown, the present invention is not limited to this, and the duty ratio can be arbitrarily selected within a range that can ensure the amount of light.

(Example 5) FIG. 6 is a diagram showing the drive waveform and optical response of the fifth example. 601 is a scanning electrode waveform, 602 is a signal electrode waveform, 603 is a composite waveform applied to the liquid crystal, and 604 is an optical response of the liquid crystal light valve. For the liquid crystal, during the selection period 111 and t21, tll is on (light transmission) and tK is off (light blocking).In the selection period, first, the alignment direction of the liquid crystal molecules is set to one of the bistable states. -■, .tt4 or v2 .tt4 is applied as a voltage pulse higher than the saturation value of the liquid crystal to align the liquid crystal to zero, or zero as a voltage pulse that does not change the bistable state during the subsequent selection period t, (t25). On the other hand, during the non-selection period ttz, (txt), a voltage pulse (vt vs)・t, 6 or (vt -42)
・tzs is applied, and the subsequent non-selection period t1 (t
2. ) is applied with zero volts as a voltage pulse that does not change the zero or bistable state. Furthermore, the period of zero volts applied to selection and non-selection tts(tt s ) e
tt y (tz y ) is the t-th period (tz 4 ) for adjusting to one of the states of bistability.
Since it is sufficiently longer than e 1; t a (tt a ), when this liquid crystal light valve is turned on, zero volts are applied during most of the selection/non-selection period and it enters a memory state, so the light caused by the voltage pulse is also emitted. It was possible to prevent this from occurring or a decrease in the amount of light, and as shown by the optical response at 604 in FIG. 6, good film last characteristics were obtained. Furthermore, in the case of the driving method of this embodiment, the liquid crystal light valve can be turned on and off simply by reversing the polarity of the signal electrode waveform, so the operating margin is large. In addition, since the light is always cut off (off state) during the non-selection period, when the liquid crystal light valve of this example was incorporated into a printing device and operated using the driving method of this example, the shape of the print on paper changed. Good printing characteristics were obtained without any problems.

(Example 6) FIG. 7 is a diagram showing the drive waveform and optical response of the sixth example. 701 is a scanning electrode waveform, 702 is a signal electrode waveform, and 705 is a waveform applied to the liquid crystal.
704 is the optical response of the liquid crystal element. The difference from the drive waveform of Example 5 is that the DC component of the signal electrode waveform is eliminated;
This reduces the DC component applied to the liquid crystal. For the liquid crystal, during the selection period "flyt! 1", tll is selected to be on (light transmission) and txt is selected to be off (light blocking). In the selection period, first, the alignment direction of the liquid crystal molecules is set to one of the bistable to bistable states. (Vt Vs)・tK4 or (vt
When V4)·tt4 is applied and on, a voltage pulse (V, -V) higher than the saturation value is used to realign the bistable state to the other state.

)・tts is applied, and if it is off, the voltage below the threshold (
vt −V3 )·tt5 is applied and does not change the bistable state. Subsequent selection period t1. .

Zero port is applied for a period of 60 °t. - During the non-selection period t12ett2, first, a voltage higher than the saturation value of the liquid crystal is applied to align the alignment direction of the liquid crystal molecules to one of the bistable states (light blocking) in the selection period. As a pulse (V, -V.

)・txt or (Vz-va)・tzy is applied, -■4 below the threshold value ・tte or -V3-t,
. is applied, and zero volt is applied during the subsequent non-selection period t1g (tts). Also, the period of zero volts applied to selection and non-selection t1゜(116)ytta(1;ts)
is the period t14 (tt 4 ) s ts s (tz
Since it is sufficiently longer than s) etty (Tax r), as in Example 1, good contrast characteristics were obtained as shown in the optical response at 704 in Fig. 7, and even when printed with a printing device. Good printing characteristics were obtained without any change in the print shape. Although a 1/2 duty drive waveform is shown in this embodiment, the present invention is not limited to this, and the duty can be arbitrarily selected within a range that can ensure the amount of light. Furthermore, the position at which a voltage pulse higher than the saturation value is applied to align one of the bistable states applied during the selection period, or the peak value of the voltage pulse higher than the saturation value, can be varied from the threshold value to the saturation value. By selecting the voltage level, the amount of on-light can be increased or decreased, making it possible to perform gradation printing.

(Example 7) FIG. 8 is a diagram showing the drive waveform and optical response of the seventh example. 801 is a scanning electrode waveform, 802 is a signal electrode waveform, 803 is a composite waveform applied to the liquid crystal, and 804 is an optical response of the liquid crystal light valve. The selection period t□□, t! is displayed on the LCD. , t1□ is selected to be on (light transmission), and 11° is selected to be off (light blocking). In the selection period, -■ is first applied as a first voltage pulse for selecting the alignment direction of liquid crystal molecules to be on or off.

tl4 or -■4 ・t! 4 is applied, and in the subsequent selection period "lfi (tl11), the peak value is (vl-VS)
A high frequency AC pulse with a pulse width tlo is applied at (V, -V4). This high frequency alternating current pulse contributes to the stability of the liquid crystal alignment by making the liquid crystal molecules parallel to the substrate due to the combination with the permanent dipole or dielectric anisotropy of the liquid crystal. Furthermore, in the subsequent period t*a, (tts), vNptts (vt·t26) is applied as a second voltage pulse to align the liquid crystal molecules to the off state. This second voltage pulse is provided to reduce variations in the amount of on-light. Next, during the non-selection period t12 (t!!), when the voltage exceeds zero or the liquid crystal threshold, a voltage pulse (Van
s)・tl? (t!?) or (7m-v4)・ety
(f; ty), and a voltage pulse having the same peak value and pulse width as the high-frequency alternating current pulse applied during the selection period as a high-frequency alternating current pulse train, and having the peak values vi and v2 and the pulse width tl. A high frequency alternating current pulse is applied. The optical response upon application of this drive waveform is shown at 804 in FIG. 8, and good contrast characteristics were obtained. In the case of this embodiment, since the liquid crystal light valve can be turned on and off simply by reversing the polarity of the signal electrode waveform, the operating temperature margin of the liquid crystal light valve is widened, and the high-frequency AC pulse can be scanned in one direction. , can be assigned to the signal electrode, allowing the use of a low voltage driver, and furthermore, in order to ensure that the liquid crystal molecules are aligned in the off state at the end of the selection period, it is influenced by the selection content of the pixel on the next scan electrode. It is characterized by a high degree of stability in on-sight. In addition, since light is always cut off during the non-selection period, when the liquid crystal light valve of this example was incorporated into a printing device and operated according to the driving method of this example, the print shape on paper did not change and good printing characteristics were obtained. was gotten. still,
Although a 1/3 data drive waveform is shown in this embodiment, the data ratio is not limited to this, and the data ratio can be arbitrarily selected as long as the amount of light can be secured.
The peak value of the high-frequency alternating current pulse may be the same when selected and unselected, or it may be a high-frequency pulse train that is biased toward the off-state polarity when not selected.

(Example 8) FIG. 9 is a diagram showing the drive waveform and optical response of the eighth example. 901 is a scanning electrode waveform, 902 is a signal electrode waveform, 903 is a composite waveform applied to the liquid crystal, and 904 is an optical response of the liquid crystal light valve. The liquid crystal displays selection periods txt, t2. , t□ is on (
(light transmission) and t2 are set to off (light blocking).

In the selection period, -V, -V,
・tl4 or -vs at, is applied, and the peak value is (V, -V) during the subsequent selection period t1s.

) and (vtva), a high frequency AC pulse train with a pulse width of t8°, t2. The peak value is (V, -V.

) and (Vs Va), a high-frequency pulse train with a pulse width tl6 biased toward the fi pole side is applied. These high-frequency pulse trains act to align the liquid crystal molecules parallel to the substrate by combining with the permanent dipole or dielectric anisotropy of the liquid crystal, thereby contributing to maintaining and stabilizing the liquid crystal alignment. Further, a subsequent period t. *(tts) is a second voltage pulse to align the liquid crystal molecules to the off state (v4-vra)・tw6
Or (V4-■5)·tta is applied. This second
The voltage pulse is provided to reduce variations in the amount of on-light. Next, the non-selection period t, 2 (t,
2), the voltage pulse (v
4-v! l ) # (Vs Vs ) e (-V
As a voltage pulse with a peak value of s ) v (v4-v, ), and a high-frequency pulse train biased in the same polarity direction as the second voltage pulse, the peak value is (VS-v7) and (vz
Va), a high frequency pulse train with a pulse width t1° is applied. Due to the voltage pulses applied during these non-selection periods, the device is always kept in an off state (light-blocked) during the non-selection period, regardless of the selection content of the selection period.

The optical response when the driving waveforms were printed is shown at 904 in FIG. 9, and good contrast characteristics were obtained. In the case of this embodiment, since the liquid crystal light valve can be turned on and off simply by reversing the polarity of the signal electrode waveform, the operating temperature margin of the liquid crystal light valve is widened, and the high-frequency alternating current current can be turned on and off by reversing the polarity of the signal electrode waveform. Since the voltage can be applied to the electrodes, it is possible to use the low voltage driver 10, and there is also a feature that there is less concern about heat generation of the board due to the application of a high frequency voltage (high frequency because the pulse train is relatively short). When the liquid crystal light valve of this example was incorporated into a printing device and operated according to the driving method of this example, good printing characteristics were obtained without changing the print shape on paper.
Although a three-duty drive waveform is shown, the present invention is not limited to this, and the duty ratio can be arbitrarily selected within a range that can ensure the amount of light.

(Example 9) FIG. 10 is a diagram showing the drive waveform and optical response of the ninth example. FIG. 10 1001 is a scanning electrode waveform, 1
002 is a signal electrode waveform, 1005 is a composite waveform applied to the liquid crystal, and 1004 is an optical response of the liquid crystal light pulp. The selection period t11*t! is displayed on the LCD. 1, tll is on (light transmission) jtt1 is off (light blocking)
is selected. In the selection period, -v6·t14 or -■5·24 is first applied as a voltage pulse greater than the saturation value of the liquid crystal in order to align the alignment direction of the liquid crystal molecules to one of the bistable states, and then the subsequent selection is performed. period tt
As a high-frequency AC pulse of s(1;zs), the peak values are (v, -v,) and (v, respectively).

-■4) A high frequency alternating current pulse with a pulse width of tlll is applied. This high-frequency AC pulse contributes to maintaining and stabilizing the bistable state by making the liquid crystal molecules parallel to the substrate through a combination with the permanent dipole or dielectric anisotropy of the liquid crystal. On the other hand, during the non-selection period t,2 (t,2), when combined with a bistable polarizing plate, a voltage pulse exceeding the saturation value of the liquid crystal is applied to create a state in which light is blocked. , (V.

-v6)・t16 or Cvs-vs)・tta is applied, and the subsequent non-selection period tl? s(t2?) is a voltage pulse that is applied as a high-frequency AC pulse during the selection period and has the same peak value and pulse width as the high-frequency AC pulse. Furthermore, the period 1m, (121)*f;ty (jtt) of the high-frequency AC pulse applied selectively and non-selectively is the period 1. ．． (124) ytts (tta), so when this liquid crystal light valve is turned on, high-frequency AC pulses are applied during most of the selection and non-selection periods, resulting in a good memory state and the light generated by the voltage pulses. Leakage and reduction in light intensity were prevented, and good contrast characteristics were obtained, as shown by the optical response at 1004 in FIG. Furthermore, in the case of the driving method of this embodiment, since the liquid crystal light valve can be turned on and off simply by reversing the polarity of the signal electrode waveform, the operating margin of the liquid crystal is large, and
Since high-frequency AC pulses can be distributed to scanning electrodes and signal electrodes, it is possible to use a low-voltage driver 10. Furthermore, according to this driving method, since light is always shut off (off) during the non-selection period, good printing characteristics were obtained without any change in the shape of the printed pixels on paper during printing.

(Example 10) FIG. 11 is a diagram showing the drive waveform and optical response of the tenth example. 1101 in FIG. 11 is the scanning electrode waveform;
1102 is a signal electrode waveform, 1103 is a waveform applied to the liquid crystal, and 1104 is an optical response of the liquid crystal element. The difference from the driving waveform of Example 9 is that the DC component of the signal electrode waveform is eliminated, and for the liquid crystal, during the selection period t, □, t, 1, 111 is on (light transmission) m and tl1 is off (light blocking). has been done. In the selection period, first, a voltage pulse (V4 V@)·tl or (
After applying v4-vt)·tta, if it is on, apply (V, -V) to realign it to the other state of the bistable state (light transmission in this example).

)・tl. A voltage pulse of
, )・t2・voltage pulses are applied. During the subsequent selection period t*s (tts), a high frequency AC pulse is applied. - During the non-selection period litu t (tz *), first, the liquid crystal is saturated to align the alignment direction of the liquid crystal molecules to one of the bistable states (light blocking) in the selection period. After the step voltage pulse shown in the period tts or tta at 1105 in FIG. applied. It is also applied to selection and non-selection.

The period during which the high-frequency AC pulse is applied t*sCtts),
t1(1;ty) is the period 1;ta(txa)t1@(
tz. ), t1° (tta), so as in Example 1, good contrast characteristics were obtained as shown in the optical response at 1104 in FIG. 11, and when printed with a printing device, Good printing characteristics were obtained without changing the print shape on paper. In this example, 1/
Although the two-duty drive waveform is shown, the duty is not limited to this, and the duty can be arbitrarily selected as long as the amount of light can be ensured. Furthermore, gradation printing is also possible because the amount of on-light can be increased or decreased by changing the position of the voltage pulse that is equal to or higher than the saturation value and applied during the selection period to align with either one of the bistable states.

[Effects of the Invention] As described above, according to the method for driving a liquid crystal light valve of the present invention, it is possible to prevent the deterioration of printing quality of a printing device due to the memory property of ferroelectric liquid crystal, and to produce a liquid crystal with excellent optical properties. It realizes a light valve and can be applied to various electronic shutters, polarizers, etc.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of the structure of a liquid crystal light valve according to an embodiment of the present invention, FIG. 1 (α) is a sectional view, and FIG. 1 Ch) is a plan view. FIG. 2 is a diagram showing the driving waveform and optical response of the first embodiment of the present invention. FIG. 3 is a diagram showing the drive waveform and optical response of the second embodiment of the present invention. FIG. 4 is a diagram showing the drive waveform and optical response of the third embodiment of the present invention. FIG. 5 is a diagram showing the driving waveform and optical response of the fourth embodiment of the present invention. FIG. 6 is a diagram showing the drive waveform and optical response of the fifth embodiment of the present invention. FIG. 7 is a diagram showing the drive waveform and optical response of the sixth embodiment of the present invention. FIGS. 8A and 8B are diagrams showing drive waveforms and optical responses of a seventh embodiment of the present invention. FIG. 9 is a diagram showing the driving waveform and optical response of the eighth embodiment of the present invention. FIG. 10 is a diagram showing the drive waveform and optical response of the ninth embodiment of the present invention. FIG. 11 is a diagram showing the drive waveform and optical response of the tenth embodiment of the present invention. FIG. 12 is a schematic diagram of printing pixels when printing is performed using a conventional driving method. 10... Part of the micro shutter 11.12...
...Substrate 13--Scanning electrode 14--Signal electrode 15--Light mask 16--Insulating layer 17--Alignment film 18-...Liquid crystal 19...Polarizing plate 201.501, 401, 501, 601, 701.8
01,901,1001,1101...
Scan electrode waveform 202.502, 402, 502, 602, 702.8
02,902,1002,1102...
Signal electrode waveform 20s, 505,405,505.6m5,705,
805, 905, 1005, 1105--
...Synthetic waveform 204.504, 404, 504, 604, 704.8
04,904,101)4,1104・・・・・・-
・Optical response 4 no. 1 (a,) , -/',, y19-1 (b) l-7! l l i VSI+lII 下－Tomota,, -t～-I X11 11 1M1
II J L near 4゜half two = : It II II if
It II2i, -, I l+
1 Qφ ■ ″”・■One day “V-Coloring 11111” ↓−+ Toe also +tx. 7cB+ll III III
III111 II III
Ill''- 1, -n-+-, 2-→shi mo- 奥・111] 11111111 11111 II lj , l, L￥11J l jl 11
・ ``1 11 ■ : 1 1 ・ 1 : )2 Figure 8 1+13 -3
Fig. 9
:ll l 11 l
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Claims (2)

[Claims] (1) In the driving method of a liquid crystal light valve, which consists of a ferroelectric liquid crystal sandwiched between substrates with scanning electrodes and signal electrodes, the electrode surfaces of which are opposite to each other, the liquid crystal is applying a first voltage pulse whose absolute value is greater than or equal to the saturation value of the liquid crystal element to align at least the alignment direction of the liquid crystal molecules to one of the bistable states depending on the display content of the pixel; At the end of the selection period or the first period of the following non-selection period, the absolute value of the bistable state to ensure alignment in one direction regardless of the display content of the pixels is equal to or greater than the saturation value of the element. In order to apply a voltage pulse of A method for driving a liquid crystal light valve, characterized in that a voltage pulse of: (2) The liquid crystal light according to claim 1, characterized in that as the voltage pulse for not changing the bistable state, a high frequency AC pulse or a high frequency AC pulse and a voltage pulse below a threshold value of the liquid crystal element is applied. How to drive the valve.