JPS6225732A - Driving method for liquid crystal cell - Google Patents

Abstract

PURPOSE:To make the free and multistep control of areas of a rotary polarized state part and a non-rotary polarized state part in the same cell possible by repeating the operation of applying voltage of specified polarity to respective electrode of one board and another board. CONSTITUTION:A basic liquid crystal cell 1 has a main electrode 9 consisting of a transparent electrode in one transparent board 2 and electrodes 5, 6 on its both sides and has a main electrode 10 and electrode 7, 8 in another board 3. Liquid crystal is clamped in a gap formed by a spacer 4 between boards 2, 3. The voltage of reverse polarity is applied to two electrodes 5, 6 for the board 2,and voltage is applied controlling the ratio of time to from rotary polarized state part and non-rotary polarized state part simultaneously and time to set electrodes 5 6 to the condition to make the whole face to the rotary polarized state, part and the ratio of area the rotary polarized state part and non-rotary polarized part is controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for driving a liquid crystal cell that is capable of area modulation using liquid crystal.

[Conventional technology]

Conventionally, liquid crystals have been used for display purposes and as light shutters to control the original transmission. Among these, when used as an optical shutter to control the transmission of light, it is generally used for a binary value of transmitting or not transmitting light.

[Problems that the invention attempts to solve]

5.The reason why liquid crystals are only used in binary values is that the voltage width at which the transition process that changes the orientation of the liquid crystal to another state is relatively narrow, and it changes depending on the temperature. This is because it is difficult to control the amount of light transmission and reflection to intermediate levels.

This invention has an original transmitting part (light-light state part) in the same liquid crystal cell.
The purpose of the present invention is to provide a method for driving an area modulation type liquid crystal cell in which a non-light transmitting part (a non-optical rotation state part) can be arbitrarily formed and transmission or reflection in this intermediate stage can be stably controlled. do.

[Means for solving problems]

The method for driving a liquid crystal cell according to the present invention is constructed by sandwiching a liquid crystal between one plate having two electrodes on both sides of a main electrode and the other plate having an electrode on at least one of the main electrodes. To drive a liquid crystal cell, the polarity of the voltage applied to each electrode on one plate is combined with the polarity of the voltage applied to each electrode on the other plate.

In addition, the voltage application time is adjusted.

[Effect]

In this invention, a spotlight state portion having a desired shape and size is formed by adjusting the application time of the voltage applied to each electrode.

〔Example〕

FIG. 1 is a perspective view showing an exploded state of a basic liquid crystal cell (hereinafter referred to as a liquid crystal cell) used in the present invention. In this figure, 1 is a basic cell, and 2 is one transparent plate ( (hereinafter referred to as the upper plate for convenience), 3 is the other transparent & (hereinafter also referred to as the lower plate), 4 is a spacer, and 5 and 6 are l! ff electrodes on the upper plate 2; 7 and 8 are electrodes on the lower plate 3; 9 and 10 are main electrodes consisting 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 becomes complicated. The basic cell 1 consists of the upper plate 2, the spacer 4, and the lower plate 3 stacked closely together, and a liquid crystal placed between the upper plate 2 and the lower plate 3 created by the spacer 4.

Next, the operation will be explained.

The inner boundaries of electrodes 5 and 6 on the top & 2 of 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 electrode 8 of the lower plate 3 are grounded. Here, electrode 7 in this case
is grounded or )c--).

FIG. 2 shows the relationship between the light transmittance when a signal voltage is applied to the electrode 6 of FIG. 1 and the positions of A and B 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 because deterioration of the liquid crystal will be reduced.

In addition, the polarizing plates installed above and below the basic cell 1 are shown with their polarization planes perpendicular to each other.

It is. When the plane of polarization of this polarizing plate is parallel, the light transmittance is reversed. An example will be shown in which a twisted nematic mode liquid crystal (hereinafter referred to as nematic liquid crystal) is used as the liquid crystal.

When 2Vtt is applied to the pole 6, the light transmittance near the position A partially decreases, and at 5■, almost no light 9 near the point A is transmitted. Further, as the voltage increases to 8V and 10V, the non-light transmitting part moves in the direction of point B, and the area of the original transmitting part decreases. This phenomenon occurs because when a signal voltage is applied to the N pole 6, a current flows in the direction of the grounded electrode 5, and the main electrode 9 acts as a resistor.
[A voltage distribution that drops like Ml is formed. On the other hand, the liquid crystal shows the voltage distributed across the main [pole 9] of the upper plate 2,
A voltage equal to the voltage difference between the grounded main electrodes 10 of the lower plate 3 is applied. On the other hand, with a liquid crystal, the orientation of the liquid crystal changes with a voltage of about 2 cm, and the light transmittance partially changes.

For this reason, the signal voltage becomes high and the position where a voltage i of 2 or more is applied to the liquid crystal spreads to the B side, thereby reducing the number of original transparent parts.

FIG. 3 specifically illustrates changes in the state of the light transmission window. (The upper side of Figure 3 is a diagram in which the direction of the arrow shown in Figure 1 is the upper side, and the arrows in the following drawings similarly indicate the upper side. (1) to (19) in the figure The voltage C of the electrode 5 is Ov, and e = 10 V only for the electrode 6. When the signal voltage S applied to the electrode 6 is +1) Ov, the entire window is transparent; At 8-2.5V in (11), there is a part (hereinafter referred to as the non-optical rotation state part 42 of the liquid crystal) where almost no light is transmitted near the point A, and to the right of it The portion where the orientation of the liquid crystal gradually changes and the light transmission gradually increases (hereinafter referred to as transition portion 43)
), and to the right of it is an optical rotation state part 41 which is a liquid crystal alignment part with good light transmission. (At 8-4V in 11D, the non-optical rotation state part 42 widens, the transition part 43 moves to the right while being slightly pinched, and the optical rotation state part 41 decreases. This tendency becomes even more remarkable at 5=7V at 0ψ. Tsuta.Mari (V)
When 5=10V and C=10V, no light was transmitted at all.

Here, when the liquid crystal is changed from a nematic liquid crystal to a strong electrospinning liquid crystal, the non-optical rotation state part 42 is in a state where the orientation direction has changed, and the optical rotation direction of light becomes a direction different from that of the optical rotation state part 41.

Therefore, no light is transmitted.

The present invention operates similarly in the case of such a liquid crystal. However, this K will not be explained in detail here, and only the trappings of the nematic liquid crystal will be explained hereafter.

FIG. 4 is a diagram showing the upper plate 2 and lower plate 3 of FIG. 1 and their connection relationship, and the spacer 4 is not shown.

In the case of FIG. 4, the electrode 5 is grounded, the electrode 6 is connected to a power source 11, and the voltage divided by resistors 12 and 13 is applied to the electrode 8. Here, the voltage divided by 1 is:
It is clear that the voltage can be applied to other power sources.

In this case, an optically rotating state portion 41 and a non-optically rotating state portion 4 are formed.
2. The distribution of the transition portion 43 is shown in FIG.

FIG. 5 shows the case where resistors 12 and 13 are equal.

Non-optical rotation state portions 42 are formed at the top and bottom, and an optical rotation state portion 41 is formed in the middle. The width of this optical rotation state portion 41 is the width of the power source 11
narrows as the voltage increases. On the other hand, resistors 12 and 13
When the resistance value of is changed, the optical rotation state part 41'9! : It is possible to move up and down.

Here, the resistors 12 and 13 can be a resistor with a fixed resistance value or a resistor that is variable in an analog manner using a variable resistor, a transistor, or the like. A similar result can also be obtained by applying a voltage corresponding to the voltage divided by the resistors 12 and 13 using a separate t-current or an amplifier.

Next, in order to organize the relationship between the light transmission distribution and the voltage applied to each electrode, we will use the cell structure shown in Figure 6 to connect each electrode to terminals A, B,
C and D are provided, and the voltage codes applied thereto will be explained. Terminals A and B shown in the figure.

C9D are connected to electrodes 6.5.7.8, respectively.

FIG. 7 shows the positive sign of the voltage applied to terminals A-D.

Negative and ground voltages are shown as +, -, and 0, respectively, and the optical rotation state distribution is shown as the state of the light transmission window 23, with an optical rotation state part 41 (white) and a non-optical rotation state part 42 (hatched). Here, the transition section 43 is omitted. As can be seen from the figure, there are four states from 5 to -A8: 2 each in the vertical and horizontal directions, downward to the right, and downward to the left. Since voltage 9 is O, it is shown here for reference.

FIG. 8 is an example of voltage waveforms versus time for reproducing all the states shown in FIG. 7. (A) in the figure,
(B), (C), (D) Each e trend A, B
,C.

This is the voltage waveform applied to 0. Terminals A and 8 and C and D
The voltage waveform applied to terminal A is symmetrical and asymmetrical with respect to ov.
Let's do this using the waveforms of and C.

The period of the voltage waveform applied to terminal C is four times the period of the voltage waveform applied to terminal AK. K is set so that there are always two occurrences. Therefore, for example, between terminal A and 0, terminal C becomes +101 10, and λ7.8.
9 states appear. Also, while terminal A is 10, VC terminal C is +, 0. +.

0, so the state 41.2.3 in FIG. 7 appears. Also, since terminal C is the same while terminal A is -, the seventh
The situation shown in Figure 4.5.6 appears.

All of these include the entire state.

Here, if the frequency of each voltage waveform is equal to or less than the response speed of withdrawal, each state is individually activated. If it exceeds this, the combined state will be obtained, and this state is shown as the light transmitting state of the light transmitting window 23 in the upper right corner of the figure. Further, the following explanation will be shown as a voltage waveform with a frequency higher than the response speed.

In this case, the size of the light transmission distribution (optical rotation state distribution) is reduced by increasing the wave height of the voltage waveform, and conversely is expanded by decreasing the wave height.

On the other hand, it has been found that the light transmission distribution can be changed by keeping the voltage constant and changing the waveform, for example by changing the pulse %l-. This will be explained next.

Figure 9 shows 7 and 8 of the seventh prisoner. Jll+ / Paper 7. This is the case where the terminal voltage sign of Oboro 6 is repeated at different times, and this is the optical rotation state distribution shown by diagonal lines in the upper right corner of FIG. In this case, the fundamental frequency did not increase and stopped; Fig. 10 shows the result in which the application time of the negative voltage was shortened. Thus, ′jIl!
If the waveform is such that the voltage application time decreases, w
The white part and 13 (ka) of the light transmission distribution shown in the upper right of Figure J9
It was revealed that the light shape and bulge 41) expand and the light transmission area changes. Using this, it becomes possible to freely change the optical rotation state distribution by changing the positive or negative voltage applied lIv.

Figure 11 is ^1 of Figure 7. Situation 2. Top 4. This is a case in which the four-element voltage sign of /shiba5 is repeated IIIK, and a chest-like distribution is clearly shown in the upper right of the figure. In this case as well, Figures 12 and 13
As shown in the figure, by creating a waveform that reduces the actual voltage application time.

The spotlight state part 41 of the optical rotation state distribution shown in the upper right of No. 11
was found to be expanding.

In the case of Fig. 12, the first half of the positive voltage application time of the voltage applied to the armature A in Fig. 111 is set to voltage Ov, the positive voltage is applied from the middle, and the first half of the negative voltage application time is Voltage? However, in the second half, the voltage OV is used, and the actual voltage application time is reduced.On the other hand, the voltage applied to terminal B is the same as the actual voltage application time of terminal B. The time is reduced by 1, and the time for voltage O■ is increased.

In the case of Fig. 13, the positive and negative voltage application times (applied to key A) do not change, and when the voltage changes to positive and negative, Ov
The actual voltage application time was reduced by setting a voltage of 1 and changing its length. Regarding terminal B, terminal A is O
The actual voltage application time is changed by setting the voltage to OV along with the time when the voltage is V. Therefore, it is possible to control the size of the chest shape Qi 41 in the light transmission window 23 by changing the time for applying a substantial voltage.

In addition, in the waveform of Fig. 11, if the voltage application time is substantially reduced to only one of terminals A and B or one terminal C and O, as in (1) and (11) of the 14th factor, A diagonally elongated optical rotation state portion 41 can be formed.

By applying pressure in this manner, compared to the symmetrical reduction and expansion of the spotlight state portion 41 as shown in FIGS. 12 and 13, the change in area can be made finer (reduction and expansion). When used as an optical system, it is possible to record finer gradations.Also, this method of changing the area of the optical rotation state portion 41 by controlling the actual voltage application time is as follows:
Since it is easy to control using a digital circuit using a constant voltage, there is an advantage that the driving circuit is simpler than the method of changing the area of the spotlight state section 41 by voltage control described before FIG. Moreover, until now, the main electrode 9 or 1
Of the voltage applied to 0, the size of the optically active part 41 was controlled by changing the time the voltage was set to OV. LCD for AC voltage or dual frequency drive!
If used, what is the threshold voltage; I! (Related AC voltage may also be applied.

In the above-described embodiments, a method has been described in which the area of the optically-rotating state portion 410 is increased by substantially reducing the voltage application time.Next, a method for reducing the area of the optically-rotating state portion 41 will be described.

@Figure 15 is an example based on the waveform in Figure 9, but terminals A and C have voltages with the same waveform as in Figure 9? It is applied. However, voltages of opposite polarity to terminals A and C are applied to terminals 8 and D, respectively, in shorter widths than those of terminals A and C, so that the voltage time of Ov becomes longer. In this way, the ninth
The area of the optical rotation state part 41 smaller than the area of the minimum optical rotation state part 41 obtained in the figure can be obtained, making it possible to reduce the area. Although the details of this cause are unclear, a qualitative explanation is possible with reference to FIG.

FIG. 16 is a diagram showing the positions on the main electrode 9 in FIG. 6 and the voltage difference between the main electrodes 9 and 10 at each position. The solid line (1) in the figure indicates that the electrode 6 (A terminal side) is negative.

Electrode 5 (B terminal side) is positive, and in actual M (41), electrode 6 (A terminal side) is positive, electrode 5 (B terminal side) is negative,
The solid line (iii) shows that electrode 6 (A terminal side) is positive and electrode 5 (B terminal side) is Ov, and the solid line (IV) shows that electrode 6 (A terminal side) is negative and electrode 5 (8 terminal side) is Ov. It is.

Here, in both cases, terminals C and D are assumed to be at Ov. V again. and -vo are positive and negative threshold voltages, respectively.

Here, in the waveform of FIG. 9, if a voltage is applied when terminals C and O are Ov, solid lines (1) and (11
) voltages are applied alternately. Therefore, that line is the threshold voltage V. Alternatively, the inside of the two points intersecting with -vo becomes the original transparent part. This is the range indicated by the arrows on both sides of the symbol X. On the other hand, suppose the solid line (11, (ii), (iii
), fly), the optical rotation state part 41 is located inside the two points where the solid line (1) intersects with the threshold voltage ■ (where lit is positive) and the solid line (11).
and (IV) narrow inside the two points where they intersect with the negative threshold voltage -vo. In other words, it is the range shown by the arrows on both sides of the symbol Y. From this, the original transmission part between the ranges of symbols X and Y is formed in the case of the waveforms (A) and (B) in FIG. 15. Similarly, the waveforms shown in FIG. 15 (C) and (D) occur in the same manner.

It is thought that the area of the optical rotation state portion 410 is reduced by the combination of the two.

The operation described so far can also be applied to the cell wiring configuration shown in FIG. 4, and the width of the optical rotation state portion 41 in the light transmission distribution shown in FIG. 5 can be arbitrarily controlled by controlling the voltage waveform. It is possible.

FIG. 17 shows an optical switch unit 21 for exposing a photoreceptor in which the cells described above are arranged in seven layers, and the substrate 22
At the top, a plurality of cell light transmitting windows 23 having the same structure as in FIG. 6 are arranged.

The signal input terminals are A and B as in the case of Fig. 6.

Shown as C and D. The configuration diagram in FIG. 18 shows the exposure source switch A/I 21 applied as a source switch for an optical printer.

The light emitted from the light source 25 is focused by the lens 26 and reaches the polarizing plate 2T and the exposure switch eye 21 shown in FIG. Here, the light is polarized according to the optical rotation state distribution of the light transmission window 23. The light that passes through the exposure light switch/a 21' passes through the hole 2B provided in the substrate 22 and the polarizing plate 29,
Only light with the same polarization plane passes through the polarizing plate 29. This light is focused onto photoreceptor 31 by self-focusing fiber 30 .

In this way, the exposure switch eye 21 using the celta of the present invention has the source for controlling the light distribution within one pixel formed on the photoreceptor 31, and is similar to halftone printing in printing. An image with area modulation is obtained.

Here, examples of the photoreceptor 31 include silver halide photography, electrophotography, and diazo photography. Further, in the explanation so far, only a light transmission type liquid crystal cell has been described, but it is clear that the present invention can also be applied to a one-dimensional reflection type liquid crystal cell.

[Specific Example 1] A cell having the configuration shown in FIG. 6 was created as follows @main electrode 9.
10 is a tin oxide film with a surface resistance of 2Ω, and electrodes 5 to 8
was formed by aluminum vacuum deposition.

A 6 μm polyester spacer was used between the upper plate 2 and the lower plate 3, and a nematic liquid crystal was placed in the gap formed by the spacer to form a cell. Also, put the polarizing plates in two places: above the upper plate 2 and below the lower plate 3.

The planes of polarization were made orthogonal starting from the top. The voltage waveform applied to each terminal was as shown in FIG. Here, the repetition frequency was 10KH, and the wave height was ±10V. As a result, an original transparent part as shown in the upper right corner of FIG. 9 was obtained. Next, as shown in FIG. 10, when the time of voltage Ov was increased, the area of the original transmission part increased.

[Specific Example 2] The same cell as in Specific Example 1Φ was used, and the voltage waveform shown in FIG. 11 was used. In this case, the repetition frequency is 5KH for Hosoko A and 8.
2nd and 4th child C and D were set to 10KHz・The wave height value was ±I
It was set as OV. As a result, although the optical rotation state portion 41 shown in the upper right corner of FIG. 11 is square, it actually shows an optical rotation state distribution close to a circle, and the center portion becomes a light transmission portion. The reason for this circular shape is unknown.

Next, when creating the waveform shown in FIG. 12, the frequencies of negative terminals C and O were increased as the voltage of Ov increased. As a result, as the time of Ov increases, the optically active quadrature 4
10 area increased.

[Specific example 3] Under the same conditions as specific example 2, 4 children A and B or - children C and D
When only the time of Ov was increased, the optical rotation state distribution was rounder overall than the optical rotation state distribution shown in FIG. 14, but a tilted circular optical rotation state portion 41 was formed.

[Specific Example 1] 4] Under the same conditions as Specific Example 2, the voltage waveform shown in FIG. 15 was applied. As a result, a circular optical rotation state portion 41 was formed that was smaller than when the waveform shown in FIG. 11 was applied.

〔Effect of the invention〕

As explained above, this invention applies pressure to the respective electrodes of one plate and the other plate by repeatedly applying a voltage of a predetermined polarity at a predetermined cycle, and the shape of the voltage waveform applied from the outside is By controlling the (1-optical rotation state in the cell?! 5 (light-transmitting part) and the plane jj[ of the non-optically-rotating state part (light-opaque part)) can be changed arbitrarily and in multiple stages. .Therefore, with a printer etc., halftone dot i +1
It has the advantage that it is possible to create an optical rotation state distribution in which the center is suitable for Y fabrication and the periphery is opaque, and it can be made to transmit light in various shapes.

[Brief explanation of drawings]

Figure 1 is a perspective view showing the disassembled state of the basic cell used in this invention, Figure 2 is a diagram showing the relationship between voltage and light transmittance in the basic cell, and Figure 3 is the state of applied voltage and light transmission window. 4 is an exploded perspective view of a cell for explaining the invention in detail, FIG. 5 is an optical rotation state distribution diagram of FIG. 4, and FIG. 6 is a diagram showing changes.
The figure is an exploded perspective view of a cell used in the driving method of the present invention, FIG. 7 is a terminal polarity and optical rotation state distribution diagram in FIG. 6, and FIGS. 8 to 13 and 15 are each of FIG. FIG. 14 is an optical rotation state distribution diagram, FIG. 16 is a voltage distribution diagram for explaining the operation, and FIG. 17 is a diagram showing examples of the voltage waveform applied to the photoreceptor, which is an application example of the present invention. Exposure source switch 7V
Fig. 18 is a schematic cross-sectional view of the original 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 B are electrodes, and 9.10 is a schematic cross-sectional view of the original printer. 11 is a power supply, 12 and 13 are resistors, 23 is a light transmission window, 41 is an optically rotating state part, 42 is a non-optically rotating state part 43 is an 'i1 transition part. Fig. 1 1 degree book 2:, r: sales 3-bottom, 1! 1: 4; space■ Fig. 2 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 23 Light transmission window Fig. 9 One hour r:I Figure 10 (A) 1 hour 1 hour Figure 12 (A) -9 ~ Question 13 Figure 1 night closed Figure 14 Figure 15 1 hour Figure 16 at Figure 17 (,:BCE3CL3 C,:8(1:5(-h5Figure 18)

Claims (3)

[Claims] (1) In a method for driving a liquid crystal cell configured by sandwiching a liquid crystal between one plate having two electrodes on both sides of a main electrode and the other plate having an electrode on at least one side of the main electrode, the method includes: For one plate, voltages of opposite polarity were applied to the two electrodes, and the two electrodes were adjusted for a time to simultaneously form an optically active state part and a non-optically active state part, and under the conditions that the entire surface was an optically active state part. A method for driving a liquid crystal cell, comprising applying a voltage while controlling a set time ratio to control an area ratio of the optically rotating state part and the non-optically rotating state part. (2) In a method for driving a liquid crystal cell configured by sandwiching a liquid crystal 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. , Apply voltages of opposite polarity to the two electrodes of both the one plate and the other plate, and set the time to simultaneously form an optically-rotating state part and a non-optically-rotating state part, and make the entire surface an optically-rotating state part. A method for driving a liquid crystal cell, characterized in that a voltage is applied while controlling the ratio of time during which the two electrodes are set to a condition, and an area ratio of the optically-rotating state part and the non-optically-rotating state part is controlled. (3) In the method for driving a liquid crystal cell configured by sandwiching a liquid crystal between one plate having two electrodes on both sides of a main electrode and the other plate having an electrode on at least one side of the main electrode, For one plate, voltages of opposite polarity are applied to the two electrodes, and the time is set to simultaneously form an optically-rotating state part and a non-optically-rotating state part, and voltages with different absolute values of the voltages are applied to the two electrodes. A voltage is applied while controlling the ratio of the time during which the optically rotating state part and the non-optically rotating state part are formed in a different state, and the area ratio of the optically rotating state part and the non-optically rotating state part is determined. A method of driving a liquid crystal cell characterized by controlling the liquid crystal cell.