JPS6347729A - Liquid crystal cell array and driving method thereof - Google Patents

Abstract

PURPOSE:To form a light transparent part and light opaque part as desired within the same cell and to permit stable control of the light transmission or light reflection of an intermediate stage at a high speed by arraying the plural cells sandwiching the liquid crystals of which the dielectric anisotropies are reversed by frequencies between one plate having two electrodes on both sides of a main electrode and the other plate having two electrodes on both sides of the main electrode. CONSTITUTION:For example, the main electrodes 9, 10 are formed of tin oxide films having 100k.OMEGA surface resistance and the electrodes 5-8 are formed by vapor deposition of aluminum. The cell is formed by using a polyester spacer sized 6mum between an upper plate 2 and a lower plate 3 and putting the liquid crystal into the space formed by said spacer. Polarizing plates are put into two points above the upper plate 2 and below the lower plate 3 so that the planes of polarization intersect orthogonally with each other successively from above. The driving method is executed by applying the signals which are generated from a pulse generator and are amplified by a power amplifier to respective terminals. The signals are inputted to the respective terminals. The frequencies are set at 2kHz for a low frequency and 50kHz for a high frequency and the wave crests are set at 60V for the high voltage of the low frequency and 10V for the low voltage. the high frequencies are changed in a 0V-60V range.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a cell array in which a plurality of liquid crystal cells are lined up that are capable of area modulation using liquid crystals, and a method for driving the cell array.

[Prior Art] Conventionally, liquid crystals have been used for display purposes and also as optical shutters that control the transmission of light. Among these, when used as an optical shutter to control the transmission of light, it is generally used for binary values, either transmitting light or not transmitting light.

[Problem that the invention seeks to solve]

In this way, the reason why liquid crystals are only used for binary values is that the voltage width at which the transition process that changes the orientation state of liquid crystals to other states occurs is relatively narrow, and that the light-transmitting and non-light-transmitting parts are operated at high speed. Because it is difficult to do so, there has not been much research into using this transition process to control the amount of light transmission and reflection to an intermediate level.

This invention is based on area modulation that allows light transmission or light reflection at this intermediate stage to be controlled stably at high speed by arbitrarily forming a light transmitting part and a light non-transmitting part in the same cell (hereinafter referred to as aperture operation). The present invention aims to provide a cell array in which a plurality of type liquid crystal cells are arranged and a method for driving the same.

[Means for solving problems]

The liquid crystal cell array of the first invention has dielectric anisotropy between one plate having two electrodes on both sides of the main electrode and the other plate having two electrodes on both sides of the main electrode. It consists of a plurality of cells sandwiching liquid crystals whose properties are reversed depending on the frequency.

In the method for driving a liquid crystal cell array according to the second invention, the applied low frequency voltage is lowered, and the low frequency voltage applied to unselected cells is made higher than the voltage to form a closed state, and these signals are The aperture state is selectively formed by superimposing a high frequency voltage.

A method for driving a liquid crystal cell array according to the third invention is to apply four types of voltages or driving voltages with different phases to each of the four electrodes, and to set a light transmitting state, an aperture state, and a light non-transmitting state to each cell of the cell array. It is to be formed.

[Effect]

In the first invention, each liquid crystal cell can be selectively controlled to be in the apertured state using a small number of electrodes and a wA dynamic circuit.

In the second invention, a liquid crystal whose dielectric anisotropy is reversed depending on the frequency is used, and the aperture operation is performed by a combination of the application of a low-frequency voltage and a high-frequency voltage, so that the aperture operation and the light-opaque state can be switched. By performing the driving at high speed and by combining both the wave height and the phase of the driving waveform, it is possible to efficiently perform the 7-trix type driving.

Further, in the third invention, there is provided a method of controlling the high frequency or low frequency voltage, and a method of keeping the high frequency or low frequency wave height constant and controlling the magnitude of the aperture operation by duty control.The former is suitable for analog circuits. , the latter is suitable for digital circuits and can be driven by either circuit.

〔Example〕

FIG. 1 is a perspective view showing an exploded state of a basic cell for liquid crystal used in the present invention, and in this figure, 1 is a basic cell, 2 is one transparent plate (hereinafter referred to as the upper plate for convenience), 3 is the other transparent plate (hereinafter the same (referred to as the lower plate), 4 is a spacer,
5 and 6 are electrodes of the upper plate 2, 7 and 8 are electrodes of the lower plate 3, and 9 and 10 are main electrodes made of transparent electrodes.

Here, polarizing plates are required above the upper plate 2 and below the lower plate 3, but they are omitted here because the diagram is complicated. The basic cell 1 has the upper plate 2, the spacer 4, and the lower plate 3 in close contact with each other, and a liquid crystal placed between the upper plate 2 and the lower plate 3, which are formed by the spacer 4.

Next, the basic operation of this basic cell 1 will be explained.

The inner boundaries of the electrodes 5 and 6 on the upper plate 2 in FIG. 1 are a and b, respectively.
shall be. Further, a signal voltage is input to the electrode 6, and the electrode 5 and the electrodes 7 and 8 of the lower plate 3 are grounded.

FIG. 2 shows the relationship between the light transmittance when a signal voltage is applied to the electrode 6 in FIG. 1 and the position of aqb in FIG. 1 using the signal voltage as a parameter.

At this time, it is preferable to modulate the signal voltage with an alternating current signal, as this will lessen the deterioration of the liquid crystal.

Further, the polarizing plates installed above and below the basic cell 1 are shown so that their polarization planes are perpendicular to each other. When the plane of polarization of this polarizing plate is parallel, the light transmittance is reversed. Further, an example in which a twisted nematic mode liquid crystal (hereinafter referred to as nematic liquid crystal) is used as the liquid crystal is used because it is easy to understand the principle.

When 2V is applied to the electrode 6, the light transmittance near the point a partially decreases, and when 5V is applied, almost no light near the point a is transmitted. Further, as the voltage increases to 8V and IOV, the non-light transmitting portion moves in the direction of point b, and the area of the light transmitting portion decreases. This phenomenon occurs because when a signal voltage is applied to the electrode 6, a current flows in the direction of the grounded electrode 5, and the main current 9 acts as a resistor. On the other hand, the liquid crystal displays a voltage that is the difference between the voltage distributed across the main electrode 9 of the upper plate 2 and the grounded main electrode 10 of the lower plate 3. On the other hand, with a liquid crystal, the orientation of the liquid crystal changes with a voltage of about 2■, and the light transmittance partially changes.For this reason, the signal voltage becomes high, and the position where a voltage of 2■ or more is applied to the liquid crystal becomes b. By expanding to the point side, the light transmitting area becomes smaller.

FIG. 3 specifically illustrates changes in the state of the cell window that transmits light. This state is called an aperture operation (a state in which a light transmitting state and a light non-transmitting state are distributed). (i) in the diagram
In -(iv), the voltage C of the electrode 5 is OV, and only in (V), C=10V. When the signal voltage S applied to the voltage S6 is Ov in (i), the entire window is in a light transmitting state (hereinafter, this part will be referred to as the light transmitting section 41), and at S=2.5V in (ii), point a There is a part near where there is almost no light transmission (hereinafter this part will be referred to as the non-light transmitting part 42), and to the right of this part there will be a part where the orientation of the liquid crystal gradually changes and the light transmission gradually increases (hereinafter this part will be referred to as the non-light transmitting part 42). There is a transition section ) 43, and on the right side there is a light transmitting section 41. (ij) 5 = 4V
Then, the non-light transmitting portion 42 expands, the transition portion 43 moves to the right while being slightly pinched, and the light transmitting portion 41 does not decrease. This tendency became even more remarkable at 5=7V in (iv). Also, 5 of (V) = 10V.

At C=10V, no light was transmitted at all.

Fig. 4 shows the case of driving under different conditions, and for easy understanding, the lower plate 3 of the cell of the structure shown in Fig. 1 is rotated at a 90° angle.
Rotate the electrodes 5, 6, 7 . . . as shown in FIG.
8 is a sectional view and an external circuit diagram shown in FIG. In this external circuit, wiring connected to electrodes 7 and 8 is grounded, and electrode 8 is connected to a connection point between voltage dividing resistors 12 and 13. Here resistors 12 and 13
The following explanation is given assuming that the resistance values are equal. Further, a DC N source is used as the power source 11, and is connected to the electrodes 5 and 6 on the upper plate 2. This power source 11 is a DC power source for convenience of explanation in FIG. 5, but the same effect can be obtained even if the power source 11 is changed to an AC power source. Furthermore, the position of ground contact was determined to make the explanation of FIG. 5 easier to understand.

FIG. 5 is a diagram showing the positions on the main electrode 9 in FIG. 4 and the voltage difference between the electrodes 5 and 6 at each position.

The solid line (i) in the figure is the voltage distribution of the main electrode 9 when voltage is applied by the power source 11. On the other hand, the dotted line is a threshold voltage at which the liquid crystal changes from an optically rotating state to a non-optically rotating state via a transition state, and exists in both polarities. Here, the solid line (
The area inside the part where i) and the two dotted lines intersect is the light transmitting part 4
1, and the outside part passes through a transition state and becomes non-light transmitting s.
Becomes 42.

FIG. 6 shows the distribution of light transmitting portions actually formed in this case. Here, the symbols a and b shown on the left side of Figure 6 are the first
Match the symbols in the diagram.

Regarding the window of the cell, non-light transmitting parts 42 are formed at the top and bottom, and a light transmitting part 41 is formed at the middle stage. The width of this light transmitting portion 41 becomes narrower as the voltage of the power source 11 is increased.

Next, in order to organize the relationship between the light transmission distribution and the voltage applied to each electrode, the terminals extending from each electrode in the cell structure shown in Figure 1 are labeled A, B, C, and D, respectively, and the voltage applied to them is This will be explained as a voltage sign. Terminals A, B, C, and D shown in the figure are connected to electrodes 6, 5, and 7°8, respectively.

FIG. 8 shows the positive sign of the voltage applied to terminals A-D.

The negative and ground voltages are each indicated by -20, and the light transmission distribution is indicated by the light transmitting part 41 (white) and the light non-transmitting part 42 (hatching). Here, the transition section 43 is omitted. As you can see from the figure, the states up to No. 8 are 2 pieces vertically and horizontally, downward to the right,
It can be seen that there are four states descending to the left. NIIL9 is voltage 0
Therefore, it is shown here for reference only.

9 is an example of a voltage waveform versus time for continuously reproducing all the states shown in FIG. 8. In the figure (
A), (B), (C), and (D) are each terminal A.

This is the voltage waveform applied to B, C, and D. Since the voltage waveforms applied to terminals A and B and C and D are symmetrical with respect to Ov, the following explanation will mainly be about terminals A and C.

The period of the voltage waveform applied to terminal C is four times the period of the voltage waveform applied to terminal A, and the period of the voltage waveform applied to terminal C is four times the period of the voltage waveform applied to terminal A.

For each state of -20, the terminal C is made to have + and - once each and O twice. For this reason, for example, terminal A
While is 0, the terminal C becomes +, Q, -, 0, and the states of N11L7, 8, and 9 in FIG. 8 appear.

Also, while terminal A is 10, terminal C is 0. -, 0, so the states No. 1, 2, and 3 in FIG. 8 appear.

Also, since terminal C is the same while terminal A is -, the eighth
States No. 4, 5.6 in the figure appear, and all the states are included.

Here, if the frequency of each voltage waveform is equal to or lower than the response speed of the liquid crystal, each state appears individually. However, if it becomes more than that, the state becomes a composite state 9, and in that state, a circular light transmitting part 41 is formed as shown in FIG. (called aperture). The reason why this aperture is circular can be found by calculating the effective voltage, but its explanation will be omitted here. In addition, the following explanation will be shown as a voltage waveform with a frequency higher than the response speed. Further, the circular diaphragm can also be formed using the waveforms shown in FIGS. 10 to 14 in the same manner as shown in FIG. 9.

Figure 10 shows Na 8, No, 3, N in Figure 8.
This is a case where the terminal voltage signs of a 7 , No., and 6 are repeated in order.

Figure 11 is No 1 p No, 2 p N in Figure 8.
This is a case where the terminal voltage codes of o, 4 p No, and 5 are repeated in order.

Figure 12 shows No, 2, No, 1, in Figure 8.
This is a case where the terminal voltage codes of No, 4, No, and 5 are repeated in order. This is basically the same as Figure 11, but whereas in Figure 11 the frequencies of terminals A and C are different, in Figure 12 the frequencies are the same and the phases of terminals A and C are shifted. This is the case. Further, as a method of shifting the position and stochastically outputting the same terminal voltage sign as in FIG. 11, there is the waveform shown in FIG. 13. In this case, the frequencies of the voltage waveforms applied to terminals A and C are different.

FIG. 14 shows a waveform where terminals A and C rise only from O to + and rise by 2, and the phases are shifted by 180°.

In any of these waveforms, there is a case where the polarity is reversed, and this corresponds to the case where terminals B and D are replaced with terminals A and C, respectively. Further, although the case where the frequency difference between terminals A and C is the smallest is mainly selected and shown, the same holds true even if the frequency difference is different from the value shown. In addition, the waveform of the AC wave used here was shown as a rectangular wave because the main purpose was to lengthen the time for which the voltage is applied effectively, but the effective voltage application time changes with sine waves, triangular waves, etc., but the same results can be obtained. It's obvious that you can get it.

The above is the basic operation and driving method of the cell of this invention.
In this method, the speed at which the optically rotating state changes to the non-optically rotating state is 0.
This is a high speed of about 1 to 10 milliseconds, but conversely, the speed of changing from a non-optically rotating state to an optically rotating state is about 1 to 2 orders of magnitude slower. For this reason, it has the disadvantage of slow operation when used as an optical switch for an optical printer, which will be described later. On the other hand, high-speed operation is possible by changing the frequency by using a liquid crystal that exhibits positive dielectric anisotropy when the frequency of the alternating current of the drive power source is low, and negative dielectric anisotropy when the frequency is high. Become. □ Figure 15 shows an example of liquid crystal characteristics showing dielectric anisotropy with respect to driving frequency, and is positive below 10 KHz.

Above that point, negative dielectric anisotropy is exhibited. This boundary point will hereinafter be referred to as the transition point. -Next, a driving method of the present invention for driving a cell using this will be explained.

When a voltage is applied at a low frequency below the change point (hereinafter referred to as low frequency), a positive dielectric anisotropy is exhibited, and the liquid crystal becomes a Home-first Robic alignment and becomes non-light-transmissive.

On the other hand, a high frequency above the change point (hereinafter referred to as high frequency)
When a voltage of By utilizing this, it is possible to increase the speed at which the state changes alternately between the non-light transmitting state and the light transmitting state.

A specific example will be described in which a cell is fabricated using an ECB liquid crystal exhibiting an electric field controlled birefringence effect as a liquid crystal having the characteristics shown in FIG. 15, and an external circuit shown in FIG. 7 is used. Here, the polarizing plates placed above and below the cell were placed so that their polarization planes were perpendicular to each other. The power supply 14 is an alternating current with a frequency below the change point, and when the switch is operated, the cell becomes non-light-transmissive. On the other hand, power supply 15
is an alternating current with a frequency above the change point, and the cell that operates this becomes a light transmitting state.

FIG. 16 is a drive waveform diagram showing an example of this, where (i) is the output of the power source 14 in FIG. 7, and (1) is the AC output of the power source 15. is a value unrelated to the ground voltage, and indicates the voltage of the power supply 11 connected to the electrode 6 when the power supply output connected to the electrode 5 is referenced. It is indicated by the marked part.The mark of Otsu will be the same in the following explanations.

The arrows and symbols in (ij) indicate that the operation that the waveforms in (i) and (ii) mean is that the light transmission window is closed in the range of the arrows on both sides of Sl and S2, and the range of the arrows on both sides of I This shows that the light transmission window is open while the aperture operation is being performed. These symbols and arrows are the same in subsequent figures.

Next, the specific operation will be explained. In the range indicated by Sl, the power supply 14 in (i) of Fig. 16 is outputting, but the power supply M1
5 has an output of 0■ as shown in (ii) of FIG. Therefore, the light transmission window is closed.

On the other hand, in the range indicated by ■, the power supply 1 in (i) of Fig. 16
4 outputs voltage under the same conditions as S.

On the other hand, as shown in (ii) of FIG. 16, the power source 15 outputs a high frequency wave whose wave height is higher than that of the power source 14. In this state, as shown in (iv) of FIG. 16, the diaphragm operation shown in the state of the light transmission window is performed.

In this case, the part of the light-transmitting window where a large high-frequency voltage difference is generated between the main electrodes 9 and 10 due to the low-frequency voltage of the power supply 14 becomes a light-transmitting state, and conversely, the voltage difference becomes small.・
In the part where there is no size, ゛ is in a non-light transmitting state and becomes an aperture.

This aperture operation is performed at high speed. On the other hand, in the range of S2 where this is closed again, the power source 14 in FIG. 16(i) continues to output, but the output of the power source 15 becomes O, so the light transmission window closes quickly. - At this time, the high-frequency voltage needs to be higher than the low-frequency voltage, so the drive voltage for the aperture operation is high. On the other hand, in order to lower this, the low-frequency voltage is lowered and the high-frequency voltage is reduced. However, in states S□ and S2 with the light transmitting window closed, the low-frequency voltage is increased, and in the aperture state, the voltage is increased. 1st to lower
When the waveform shown in FIG. 7(i) is used, an aperture operation with a clear outline and less decrease in contrast) can be obtained.

Next, the drive waveform for circular diaphragm operation will be explained.

(A) to (D) in Fig. 18 are terminals A to D of the cell in Fig. 1.
This is the voltage waveform input to. S with the light transmission window closed
In the range of , low frequency voltage is input to terminals A and B with the same phase. On the other hand, the voltage at terminals C and D is Ov. Next, in the range indicated by I where the aperture operation is performed, a high frequency voltage of 3f is applied to the terminals A and B in addition to a low frequency voltage of the same phase.

Further, a high frequency voltage is applied to terminals C and D.

In this case, as shown in Fig. 19, the aperture operation is such that the central circular part becomes the light V-transmitting part 42 and the peripheral part becomes the light-transmitting part 41, and the state shown in Fig. 9(E) is reversed. state. This state is reversed by making the planes of polarization of the polarizing plates provided above and below the cell parallel, and shows the same state as in FIG. 9(E).

Next, in the range s2 where the light transmission window closes from the aperture operation,
The outputs of all terminals A, B, C, and D are in the same state as Sl and quickly become non-light transmitting state.

This cell uses an electric field both to change the direction of the molecules and to return them to their original direction, so they can switch quickly between the aperture state and the non-light transmitting state.

In this case as well, in order to reduce the high frequency driving voltage, it is effective to reduce the low frequency voltage only during the aperture operation. FIG. 20 shows the voltage waveform.

In the aperture state, the low frequency voltage used for the waveforms of (A) and (B) in FIG. 18 was lower than in the states S1 and S2 with the light transmission window closed, and the high frequency voltage was set to m.

In this case as well, a sharp aperture operation was achieved with little reduction in contrast.

Next, high-frequency waveforms used when performing an aperture operation using drive waveforms such as those shown in FIGS. 17, 18, and 20 will be described.

FIGS. 21 to 24 show applications of the drive waveforms for the aperture operation shown in FIGS. 10 to 13.

Also in these voltage waveforms, each terminal A, B.

It is preferable to display all four types of voltage waveforms applied to C and D as shown in Figure 18, but the voltage waveforms applied to terminals A and B and C and D are symmetrical with respect to OV. Therefore, terminals A and C will be explained below, and explanations about terminals B and D will be omitted.

Figure 21 shows &8. of Figure 8. Lice 3. &, 7. This is a case where the terminal voltage signs in No. 6 are sequentially repeated at high frequency.

FIG. 22 shows Nll, N12. in FIG. N14. This is a case where the terminal voltage sign of N15 is sequentially repeated at high frequency.

Figure 23 shows &2 in Figure 8. This is a case where the terminal voltage signs of Nll, No, 4, 1 and 5 are repeated in order at high frequency.

This is basically the same as Fig. 22, but whereas in Fig. 22 the frequencies of terminals A and C are different, in Fig. 23 the frequencies are the same and the phases of terminals A and C are shifted. This is the case. Further, as a method of outputting the same terminal voltage sign as in FIG. 22 stochastically by shifting the position, there is the waveform shown in FIG. 22. In this case, the frequencies of the voltage waveforms applied to terminals A and C are different.

By using these high frequency voltages in the waveforms shown in FIGS. 17, 18, 2O, etc., it is possible to perform the aperture operation.

In the explanation so far, the magnitude of the aperture operation has been controlled by controlling the wave height of the voltage waveform.

On the other hand, we have found that the magnitude of the aperture operation can be changed by keeping the voltage constant and changing the pulse width (duty) of the high frequency. This will be explained next.

Figure 21 shows Nch 8, Na 3, N in Figure 8.
25 shows a case in which the terminal voltage signs o, 7, No, and 6 are repeated in order, but the fundamental frequency in this case remains unchanged and the application time of the positive or negative voltage is shortened. As described above, it has been found that if the waveform is such that the voltage-free time increases and the actual voltage-application time decreases, the radius of the circle of the circular diaphragm operation increases and the light transmission area changes. Further, by changing the voltage-free time of the drive waveform shown in FIG. 21, the width and radius of the circle of the non-light transmitting part of the aperture operation could be changed in the same way. In this way, by controlling the ratio of the voltage application time to the voltage non-application time, it is possible to control the size of the aperture state portion of the light transmission window 23. However, the method of changing the area of the aperture operating part by controlling the actual voltage application time is easy to control using a digital circuit using a constant voltage. Compared to wAIi11
This has the advantage of simplifying the circuit.

Next, a cell array in which a plurality of cells of the present invention are arranged will be explained.

FIG. 26 is a diagram showing a part of the arrangement of the electrodes 5 and 6 and the main electrode 9 on the upper plate 2 when a plurality of cells shown in FIG. 1 are arranged side by side. FIG. 27 shows a part of the arrangement of the electrodes 7.8 and the main electrodes 10 on the lower plate 3.

In this cell array, each electrode of one cell is 5,6°7.8
are connected to two main electrodes 9 and 10.

This is 4
Because it requires multiple drive circuits and has a large circuit burden,
This has the purpose of reducing the number of drive circuits by half, and this also reduces the number of wiring lines, lowering the wiring density, and facilitating manufacturing.

FIG. 28 is a diagram showing the outline of the arrangement of wiring and transparent electrodes, showing a state in which FIG. 26 and FIG. 27 are superimposed, and the upper plate 2
The wiring on the lower board 3 is shown as a solid line, and the wiring on the lower board 3 is shown as a broken line. In addition, the state of the wiring has been changed slightly to make the position of the wiring clearer. This wiring is characterized in that the two light transmitting windows 21 to which the wiring on the upper plate 2 is connected and the two light transmitting windows 21 to which the wiring on the lower plate 3 is connected are alternately shifted. By the way, the terminals connected to each electrode 5 and 6 are A1, A2 and B1.
and B2, and they were arranged alternately. Also, the terminals connected to each electrode 7 and 8 are connected to C1, C2 and Dl.
and B2, and they were arranged alternately.

Further, symbols such as W1 to WIO are attached to each light transmission window 21.

Next, a method of driving this cell will be explained.

As explained above, this cell is in a closed state when the voltage of the low frequency is higher than the voltage of the high frequency, and is in the constricted state or the fully open state when the voltage relationship is reversed.

Therefore, for example, in order to bring W5 of the light transmission window 21 into the aperture state, the low frequency voltages applied to the terminals AI and A2 should be low voltages VL of the same phase, and the aperture operation shown in FIGS. W5 of the light transmission window 21
By superimposing a similar high frequency on the terminals CI and C2 connected to the W5 of the light transmitting window 21, the W5 of the light transmitting window 21 becomes in the aperture state. On the other hand, W4. of the light transmission window 21 connected to these terminals. W
6 have terminals DI, D2 and Bl connected respectively.
, B2 are applied with a low frequency voltage Vn higher than the high frequency, so that W4 and W6 of the light transmission window 21 do not cause an aperture operation due to the high frequency voltage applied to W5 for the aperture. By this operation, terminals D1 and B common to W4 of the light transmitting window 21 are connected.
W3 of the light transmission window 21 and W6 of the light transmission window 21 with 2
W7 of the light transmitting window 21 having a common terminal Bl and 82 is in a closed state. On the other hand, since W8 and W2 of the light transmission window 21 are not subject to these limitations, they can be brought into the aperture state in the same manner as W5 of the light transmission window 21 described above. In this way, in the upper row of the light transmitting windows 21, the W of the light transmitting windows 21 is
Next to 5 is Wll, Wl7. W23. . . . The aperture operation is possible for one out of every three windows, and the light transmission window 2
1 in the lower row W2. W8. Wl4.・・・・・・
・Aperture operation is possible for one out of every three lenses. Next, moving the aperture operation to, for example, W7 of the light transmission window 21 can be accomplished by applying the same signal as the operation of W5 of the light transmission window 21. At this time, the light transmitting windows 21 that can perform aperture operations at the same time are Wl, Wl3°Wl9 in the upper example.
etc., and in the lower row W4. WIO, Wl6, etc. Furthermore, in the same manner, W3. of the light transmitting window 21. W
9. Wl5. W21 and W6. Wl2. It is possible to narrow down Wl8 etc. at the same time. By using the method B in this way, it is possible to perform the aperture operation on all pixels by performing the aperture operation six times.

FIG. 34 is a diagram showing specific waveforms when the above WXArJjJJ method is performed continuously.

The waveform (1) in FIG. 34 is the waveform applied to the terminals A1 and A2 connected to W5 of the light transmitting window 21, and the waveform similar to this is the waveform applied to the terminals A1 and A2 connected to W5 of the light transmitting window 21. It is applied to the terminals AI, A2 or Bl, B2 of the illustrated path. However, when the size of the aperture is different for each light transmission window 21, the high frequency voltage is different. On the other hand, the waveform of (2) in FIG. 34 is the waveform of W5. Wll.

Terminals CI, C2 and DI connected to Wl7, etc.
is applied to

The waveforms in (3) in FIG. 34 are Wl and W7 of the light transmission window 21.
゜Terminal AI, A2 or Bl, B connected to Wl3 etc.
2. Similarly, the waveform of (4) in FIG. 34 is the waveform of W3. W9. Terminal CI connected to Wl5 etc.
.

C2 or DI, and the waveform of (5) in FIG. 34 is applied to W3. of the light transmission window 21. W9. The waveform shown in (6) in FIG. 34 is applied to the terminals AI, A2 or Bl, B2 connected to Wl5, etc., and the waveform shown in (6) in FIG.
Terminal CI, C2 or DIpD connected to Wl3 etc.
2. Here, these high frequencies have waveforms having the relationships shown in the explanations of FIGS. 21 to 25 for each cell.

When the signal shown in FIG. 34 is applied under such conditions, all the light transmitting windows 21 are in a closed state at the moment indicated by range S1 to 87. On the other hand, in (1), the light transmission window 21 has W5. Wll
, Wl7 etc. are in the aperture state, and in ■2 the light transmitting window 21
Wl, W7. Wl3, etc. are in the aperture state, and in ■3, W2. of the light transmission window 21. 'W8. W14 etc. are in the aperture state, and in ■4, W4. of the light transmitting window 21. WIO.

Wl6 etc. are in the aperture state, and I5 is the W of the light transmission window 21.
3. W9. Wl5, etc. are in the aperture state, and in I6, W6. Wl2. Wl8 etc. are in the aperture state, and all the light transmitting windows 21 can be individually brought into the aperture state.

Next, another more efficient driving method will be explained.

FIG. 29 shows four basic low frequency waveforms used in the drive waveforms shown in FIGS. 19 and 21, and the voltages applied to the liquid crystal when they are applied to the cell.

(1) to (4) in FIG. 29 are basic waveforms, and (1) and (2) have the same wave height but opposite phases. (3
) and (4) have the same wave height, but are higher than (1) and (2) <
, (31 and (1), and (4) and (2) have the same phase.

The waveforms (5) to (8) are obtained by applying the basic waveform (1) or (2) to the electrode 5 or 6 of the upper plate 2, and
) is the voltage applied to the liquid crystal when the fundamental waveform (51 is the fundamental waveform (1)) is applied to the electrode 7 or 8 of the lower plate 3.
(3), (61 applies (2) and (3), (7) applies (2) and (4), (8) applies (1) and (4) between upper plate 2 and lower plate 3. As you can see, the voltage applied to the liquid crystal is the difference between the two voltages when the phases match, and the sum of the two voltages when the phases are opposite.

On the other hand, the t! The upper side of the light transmission window 21 is A1. Consisting of cells connected to A2 and C1 and C2 terminals, and cells connected to Bl, B2 and DI, and B2 terminals, the cells lined up on the bottom are B1°B2, CI, and C2.
It consists of cells connected to terminals 2 and AI, A2, DI, and B2. For this purpose, low frequency waves of waveforms (1) and (2) in FIG. 29 are applied to AI, A2, Bl, and B2 of the cell in FIG. 28, respectively, and C1, C2, and D of the cell in FIG.
When the low frequencies (3) and (4) in FIG. 29 are applied to A2 and B2, respectively, AI, A2.
CI, C2 and Bl, B2. Low frequency waves with low wave heights as shown in (5) and (7) in FIG. 29 are applied to the liquid crystals of the cells connected to the terminals DI and B2, respectively.

On the other hand, cell B1 in the lower column of FIG. B2.
C1°C2 and AI, A2. The liquid crystals of the cells connected to the DI and B2 terminals are connected to (6) and (8) in Fig. 29, respectively.
) is applied with a high wave height and low frequency.

Therefore, the wave height of the high frequency can be changed to (5) or (7) in Figure 29.
) Higher than the wave height < , lower than (6) or (8),
When high frequencies are superimposed and applied to each terminal as shown in Figures 21 to 25, in this case, only the light transmitting windows in the upper row in Figure 28 are in the aperture state, and the light transmitting windows in the lower row are in the aperture state. Can be closed. Further, at this time, the aperture operation of the light transmitting window in the upper row can be made to an arbitrary size by controlling the high frequency voltage applied to each terminal.

Next, only the light transmitting windows in the lower row are set to the aperture operation, and the light transmitting windows in the upper row are closed. The waveforms (1) and (2) in FIG. 29 are continuously applied to 82, and the waveforms (4) in FIG.
) and (3) are applied. In this state, by applying a high frequency wave for diaphragm operation in a superimposed manner to each terminal, only the light transmitting windows in the lower row can be brought into the diaphragm state.

Next, a specific waveform that moves from the closed state to the aperture state and then returns to the closed state will be explained.

(A) and (B) in FIG. 30 are terminals AI in FIG. 28, respectively.

A2 and B 1. This is the waveform applied to B2. In the range 81 in which the light transmission window 21 is closed, low frequency voltages are input to the terminals Al, A2 and B1, B2 with opposite phases. Next, in the range indicated by I where the aperture operation is performed, terminal A
A high frequency voltage is superimposed on a low frequency voltage and is applied to I, A2 and Bl, B2. The high frequency waveform at this time is as shown in FIGS. 21 to 25. A low frequency voltage is applied in the range of the next state S2 in which the light transmission window is closed.

The waveform of (A) in Figure 31 is the same as the waveform of (person) in Figure 30, and in order to clarify the relationship between the waveforms in (C) and (D) of Figure 31, FIG. Also, the second
This is the waveform applied to terminals CI, C2 and DI, B2 in FIG. (C) in Figure 31 and (DJ is (person) in Figure 31)
Compared to , the low frequency phase is the same in the ranges 81 and 52, but the wave heights are different. Further, the high frequency in the range of It has a waveform relationship between the high frequency shown in FIG. 30 and the conditions for the aperture operation explained in FIGS. 21 to 25.

Here, this frequency condition is AI in FIG.

This is the same condition as when the low frequency waves applied to the terminals A"2, CI, and C2 are in opposite phase, and the low frequency waves applied to the terminals B1 and B2 and Dl and B2 are in the same phase. The row of light transmitting windows is in the aperture state, and the upper row of light transmitting windows is in the closed state.

On the other hand, contrary to this relationship, when a low frequency wave of the same phase is applied to AI, A2 and CI, C2, and a low frequency wave of opposite phase is applied to Bl, B2 and DI, I, D2, the upper light transmission window is in the aperture state.

The lower light transmitting window is in a closed state. Therefore, AI, A2 and CI, C2 or Bl, B2 and D in FIG.
By changing the phase of the low frequency input to I and B2 at an appropriate time in the range of 81, 82, etc., the aperture state of each light transmitting window is controlled by dividing it into the upper row and lower row of light transmitting windows. be able to.

(C) and (D) in Figure 32 are (C) and (D) in Figure 31, respectively.
This waveform is an improved waveform of D), in which a high low-frequency voltage is always applied to the liquid crystal cell in the closed state before and after the aperture state I, and the phase of the low frequency is reversed when the aperture state I is reached. When the aperture state ends, the phase is returned to the original phase. This has the advantage that the speed of returning from the contrast state of the light transmitting portion and the light non-transmitting portion in the diaphragm state to the closed state becomes faster, as described in FIG. 20.

The driving method explained above is a driving method based on the circular aperture operation, but if the method described in B is modified, it is possible to
It is possible to perform the aperture operation shown in the light transmission window in the figure. As this method, for example, (21, (
41. There is a method of eliminating the high frequency signal in (6) and continuing the grounded state, and a method of eliminating the high frequency component of the signals in FIGS. 30 and 32. In this case, the signals input to the terminals CI, C2 and DI, B2 on one board are common to both. Therefore, when using only this method, a cell array in which either active 7 or 8 is omitted can be used as (e).

Next, an example of application of this cell will be explained.

FIG. 33 shows an application of the cell array described above as an optical switch for an optical printer.

The light emitted from the light source 31 is condensed by a lens 32, passes through a polarized tip plate 33, and reaches the exposure light switch array 20 shown in FIG. The light that has passed through the exposure light switch array 2o passes through the polarizing plate 33 and the hole 23 provided in the substrate 22, and only the light whose plane of polarization is aligned passes through the polarizing plate 34.This light is connected to the photoreceptor 36 by the self-focusing fiber 35.
The light is focused on.

When the exposure light switch array 20 using the cell of this invention is used, the light whose light distribution within one pixel is controlled is transmitted to the photoreceptor 36.
An area-modulated image similar to halftone dot printing in printing is obtained. Here, the photoreceptor 36 is a silver halide photograph or an electrophotograph.

Examples include diazo photographs. In addition, although the explanation so far has described only a light-transmitting liquid crystal cell, it is clear that the present invention can also be applied to a light-reflecting liquid crystal cell.

Next, a specific example will be explained.

[Specific Example 1] A cell array having the configuration shown in FIG. 28 was created as follows. The main m-poles 9 and 1o are made of tin oxide film with a surface resistance of 100Ω, and the electrodes 5 to 8 are formed by aluminum vapor deposition. A 6 μm polyester spacer is used between the upper plate 2 and the lower plate 3. Liquid crystal (NTTF-01
Chisso company! ! and made a cell. In addition, the polarizing plate is
They were placed in two places, one above the upper plate 2 and the other below the lower plate 3, so that the planes of polarization were perpendicular to each other in order from the top. The driving method was to input a signal obtained by amplifying the pulse generator signal with a power amplifier to each terminal. As for the signal, the waveform shown in FIG. 34 was inputted to each terminal, and the high frequency waveform was set to the waveform shown in FIG. 23. The low frequency is 2KHz
, the high frequency was 50KHz. Moreover, the wave height was changed in the range of Ov to 60V for the high frequency, with the high voltage of the low frequency being 60V, and the low voltage being IOV.

When the high frequency was about 10 V or more, an aperture operation was observed, and all the light transmitting windows operated sequentially according to the timing shown in the range from No. 1 to No. I6 in FIG. 34.

[Specific Example 2] Using a cell array under the same conditions as Specific Example 1, a signal (j second
The waveforms shown in FIGS. 9 and 30 were input to each terminal, and the high frequency waveform was set to the waveform shown in FIG. 23.

The low frequency shown in Figures 29 and 30 is 2KHz.
, the high frequency was 50KHz. Matoko, wave height is 3rd
The low frequencies of (A) and (B) in Figure 0 are ±30V, the low frequencies of (C) and (D) in Figure 31 are ±35V, and the high frequency is OV.
It was varied in the range of ~60V.

Terminal AI of each waveform of FIG. 30 (A) and (B).

A2 and Bl were placed in B2.

On the other hand, the waveforms of (C) and (D) in FIG.
2, DI, and D2 alternately, the aperture operation of the upper and lower rows can be performed alternately, and a light transmitting window of any size can be applied to a light transmission window at any position in proportion to the high-frequency voltage. We were able to form an aperture state.

Using this method, all the cells are divided into two columns and driven, so the time required for driving is doubled, but the driving circuit is halved and a cell array with reduced wiring density can be used.

[Specific Example 3] By using a cell array under the same conditions as in Specific Example 1 and using the driving method shown in FIG. 32, it was possible to perform a circular aperture operation on a light transmission window at an arbitrary position.

At this time, the light transmission through the non-light transmitting portion was lower than in Example 1, and the speed at which the contrast diaphragm state changed from the closed state was increased.

〔Effect of the invention〕

As explained above, the first invention according to the present invention is
Since the liquid crystal that makes up the cell array uses a material whose dielectric anisotropy is reversed depending on the frequency, an array consisting of multiple cells can be divided into multiple parts by using driving voltages at two frequencies and phases at various wave numbers. The number of HA control circuits and wiring can be reduced.

Further, the second aspect of the present invention is capable of switching between the fringing operation and the light-opaque state at high speed.

Further, the third aspect of the present invention has the advantage that the wave height of the low frequency wave is constant and the magnitude of the aperture operation can be controlled by duty control.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing the exploded state of a basic cell for liquid crystal of this invention, Fig. 2 is a diagram showing the relationship between voltage and light transmittance in the basic cell, and Figs. 3 and 6 are applied voltage. FIG. 4 is a cross-sectional view of a cell and a drive circuit for explaining an embodiment of the present invention, and FIG. 5 is a diagram showing the main parts of FIG. 4. Voltage distribution diagram, FIG. 7 is a cross-sectional view and a diagram showing a drive circuit for explaining another embodiment of the present invention, FIG. 8 is a diagram showing terminal voltage signs and light transmission distribution, and FIGS. 9 to 14 The figure shows the waveform for driving this cell, Figure 15 shows the relationship between the dielectric anisotropy and the driving frequency of the liquid crystal used in this invention, and Figures 16 to 1
Figures 8 and 20. FIGS. 21-25 and 29-32. 34 is a diagram showing the driving waveform for operating the cell of the present invention, FIG. 19 is a diagram showing the aperture operating state, and FIGS. 26 and 27 are the upper and lower plates of the liquid crystal cell array of the present invention, respectively. FIG. 28 is a configuration diagram of a liquid crystal cell array of the present invention, and FIG. 33 is a schematic cross-sectional diagram of an optical printer. In the figure, 1 is a basic cell, 2 is an upper plate, 3 is a lower plate, 4 is a spacer, 5 to 8 are electrodes, 9 and 10 are main electrodes, 11.14.1
5 is a power supply, 12.13 is a resistor, 21 is a light transmission window, 41
42 is a light-transmitting portion, 42 is a non-light-transmitting portion, and 43 is a transition portion. Figure 1 9.10: Work & Figure 2 One position Figure 4 Figure 6 Figure 7 Figure 8 Figure 9 (E) One hour Figure 10 One hour Figure 11 - Ginbin Figure 12 Figure 13 Figure 14 Figure 151 One round order (KH Figure 16 (iV) (iii) Hs1+I 1,52-'-J. Figure 17 (iii) +S++ I-to S2 → Figure 18-g? Agony Figure 19 Figure □ Time P5 Figure 21 Figure 1 hour Figure 1 hour Figure 23 Figure 24 Figure 1 hour Figure 25 (A) 1 hour Figure 26 Figure 27 Figure 28 Figure 29 Figure 30 Figure □ Time opening Figure 31 Figure 1, -51-→-1+52← Figure 32 -5+-±-1fSz← Figure 33

Claims (4)

[Claims] (1) Two electrodes on both sides of a transparent electrode on one plate,
One or two transparent electrodes are provided on the other plate at positions corresponding to the transparent electrodes, and a liquid crystal whose dielectric anisotropy is reversed depending on the frequency is sandwiched between the one plate and the other plate. In a cell array in which a plurality of cells are arranged, two electrodes on one plate of two adjacent cells are respectively connected to two wirings, and one electrode on the other plate of these two cells is connected to two wirings. Alternatively, a liquid crystal cell array characterized in that two of the electrodes are each connected to one or two electrodes of the other plate of two adjacent cells. (2) Having two electrodes on both sides of the transparent electrode on one plate,
A transparent electrode provided at a position corresponding to the transparent electrode on the other plate has one or two electrodes, and a liquid crystal whose dielectric anisotropy is reversed depending on the frequency is sandwiched between the one plate and the other plate. In a cell array in which a plurality of cells are arranged, the two electrodes on the one plate of two adjacent cells are respectively connected to two wirings, and the electrodes on the other plate of the two cells or In a method for driving a liquid crystal cell array in which two of the electrodes are each connected to one or two electrodes of the other plate of two adjacent cells, the voltage is applied when a selected cell is brought into a narrowed state. The low frequency voltage is reduced,
A low frequency voltage applied to unselected cells is higher than the lowered voltage to form a closed state, and a high frequency voltage necessary for an aperture operation is superimposed on these signals to selectively form an aperture state. A method for driving a liquid crystal cell characterized by: (3) Having two electrodes on both sides of the transparent electrode on one plate,
One or two transparent electrodes are provided on the other plate at positions corresponding to the transparent electrodes, and a liquid crystal whose dielectric anisotropy is reversed depending on the frequency is sandwiched between the one plate and the other plate. In a cell array in which a plurality of soldered cells are arranged, two electrodes on one plate of two adjacent cells are connected to two wirings, and one electrode on the other plate of the two cells is connected to two wirings.
In the method for driving a liquid crystal cell array, in which one or two electrodes are respectively connected to one or two electrodes on the other plate of two adjacent cells, the electrodes on the one plate are connected to the electrodes on the other plate. The low frequency voltages applied are two types of signals with opposite phases, and the low frequency voltages applied to the electrode on the other plate are two types of signals with opposite phases, and one of the The voltage is different from the low-frequency voltage applied to the electrode on the one plate, and the low-frequency voltage and phase applied to the electrode on the one plate are different from the low-frequency voltage applied to the electrode on the other plate. A closed state is formed by varying the low frequency voltage applied to the liquid crystal using a phase difference, and a high frequency voltage necessary for an aperture operation is superimposed on these signals to selectively form an aperture state. A method for driving a liquid crystal cell array characterized by: (4) In the closed state before and after the narrowed state of the selected cell that forms the closed state, the phases of the low frequency waves applied to the upper plate and the lower plate are reversed, and in the narrowed state, the upper plate and the lower A method for driving a liquid crystal cell array according to claim 3, characterized in that the phases of the low frequency waves applied to the plates are made to be the same.