JPH0192720A - Liquid crystal optical shutter - Google Patents

Abstract

PURPOSE:To execute a diaphragm operation by one kind of signal by constituting the titled shutter so that the ratio R1/R0 of a resistance R0 of a liquid crystal, and a surface resistance R1 of at least one of two pieces of opposed transparent conductive substrates becomes larger than '1'. CONSTITUTION:A liquid crystal cell 1 is prepared by using transparent electrodes 9, 10 whose surface resistance is the same as or larger than a resistance of a liquid crystal, and when a voltage is applied between two pieces of transparent electrodes 9, 10, a potential difference distribution is generated in the surface of the liquid crystal cell 1, therefore, a light transmission part and a light cutting-off part corresponding thereto are formed in a cell window. Also, by varying an applied voltage, a ratio of the light transmission part and the light cutting-off part is varied, therefore, a numerical aperture can be controlled freely. Moreover, by a shape of metallic electrodes 5-8 formed on the transparent electrodes 9, 10, the light transmission part of an arbitrary shape can be formed. In such a way, a diaphragm operation can be executed by one kind of voltage signal.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical field to which the invention pertains The present invention relates to an optical shutter whose light transmission area can be modulated by the operation of a liquid crystal cell.

(2) Conventional techniques and their problems Conventionally, liquid crystals have been used in display devices for characters and images, and have also been used as optical shutters to control the transmission of light. Among these, when used as an optical shutter for controlling light transmission, it has generally been used as a binary value: either light is transmitted or not. In response to this, we created a liquid crystal cell with metal electrodes on both sides of a transparent electrode, and created a light-transmitting part and a light-opaque part in the liquid crystal cell by creating a potential gradient in the metal electrodes on the same transparent substrate. (hereinafter referred to as aperture operation), it has been found that by controlling the potential gradient, the ratio of light-transmitting areas to light-opaque areas can be changed arbitrarily (Japanese Patent Application No. 617181912). However, in order to perform the aperture operation using this method, it is necessary to send at least two types of voltage signals to the liquid crystal cell, which also has the disadvantage of requiring a large number of wiring lines.

(3) Object of the Invention In order to solve these drawbacks, the present invention provides a liquid crystal optical shutter in which the liquid crystal cell is improved so that the aperture operation is performed using one type of signal.

(4) Structure and operation of the invention The present invention will be explained in detail below with reference to the drawings.

FIG. 1 is a perspective view showing an example of the disassembled state of the liquid crystal cell according to the present invention, in which 1 is the liquid crystal cell, 2 is one transparent substrate (hereinafter referred to as the lower plate), and 3 is the other transparent substrate ( 4 is a spacer, 5 and 6 are metal electrodes of the lower plate 2, 7.8 are metal electrodes of the upper plate 3, and 9 and 10 are transparent electrodes.

Here, a polarizing plate may be required above the upper plate 2 or below the lower plate 3, but it is omitted here because it would complicate the drawing. These upper plate 2, spacer 4 and lower plate 3
A liquid crystal cell 1 is one in which the upper and lower plates are brought into close contact with each other and a liquid crystal is inserted into the gap between the upper and lower plates created by the spacer 4. As a result, a rectangular light transmitting part a bcd surrounded by the electrodes 5,6,7,8 is formed in the liquid (hereinafter this will be referred to as a cell window).

Here, the transparent electrodes 9 and 10 are electrodes made of indium oxide or tin oxide transparent conductive film (usually called ITO film electrodes or NESA film electrodes), and the metal electrodes 5 to 8 are metals on which aluminum or chromium is vapor-deposited. Although electrodes were used, these are not necessarily limited to this example, and any metal electrode may be used as long as it has lower resistance than a transparent electrode and blocks light.

Next, the basic operation of this liquid crystal cell 1 will be explained with reference to the drawings.

First, a conventional aperture operation method will be explained. The inner boundaries of the metal electrodes 5 and 6 on the lower plate 2 in FIG. 1 are designated as a and b, respectively. When a positive voltage is applied to the electrode 5 and a negative voltage is applied to the electrode 6, a current flows through the transparent electrode 9 from the electrode 5 toward the electrode 6. At this time, since the transparent electrode 9 acts as a resistor, a voltage distribution is formed in the transparent electrode 9 that drops almost linearly from the electrode end a toward the electrode end. This situation is shown in FIG. 2 (1), where the solid line ▪ represents the voltage distribution formed between the electrode ends a and b.

On the other hand, when electrodes 7 and 8 of the upper plate 3 are grounded, the transparent electrode 10
Since the voltage is 0.2 over the entire surface, a voltage distribution as shown in the figure is formed. Therefore, the two transparent electrodes 9 and 1
0, a potential difference equal to the voltage difference between ■ and ■ is generated, and this is applied to the liquid crystal sandwiched between these transparent electrodes 9 and 10. By the way, in general, liquid crystals have something called an operating threshold. If the absolute value of the voltage applied to the liquid crystal is less than the threshold, the liquid crystal will not operate, and the absolute value of the voltage will not exceed the threshold. For example, liquid crystals have the property of operating.

Therefore, in FIG. 2 (1), the area 4 where the potential difference between the two transparent electrodes exceeds the liquid crystal operating threshold indicated by the dotted line.
2, the liquid crystal operates, but the liquid crystal does not operate in the region 41 where the operating threshold Vl is not exceeded.

-As an example, liquid crystal cell 1 is a twisted nematic cell,
When the two polarizing plates are placed in a crossed nicol state, the region 41 becomes a light transmitting state and the region 42 becomes a light blocking state. When this state is viewed from the top of the liquid crystal cell 1, it becomes as shown in FIG. 2 (2), with light blocking regions 42 being formed on both sides of the cell, and only the central region 41 being in a light transmitting state.

The above is an explanation of the conventional aperture operation method of a liquid crystal cell.

The liquid crystal optical shutter according to the present invention has the function of realizing the same aperture operation as described above by simply providing a potential difference between the two transparent electrodes 9 and 10 without providing a potential difference between the electrodes 5 and 6. It is. Hereinafter, the principle of operation will be explained in detail.

In FIG. 1, at least one of the two transparent electrodes 9 and 10 has a surface resistance (referred to as R+) equal to or greater than the resistance (referred to as R) of the liquid crystal.

For example, the transparent electrode 9 on the lower plate 2 is a transparent electrode with a surface resistance 10 times that of the liquid crystal, and the transparent electrode 10 on the upper plate 3 is
A transparent electrode with a surface resistance less than 1/10 of the resistance of liquid crystal was used. A voltage v0 was applied to the electrode 5 of the lower plate 2, the electrode 6 was opened, and the electrodes 7 and 8 of the upper plate 3 were grounded. At this time, a voltage distribution ■ as shown in FIG. 3(1) was formed between the liquid crystal cell terminals a and b. Since the upper plate electrode is grounded, the voltage distribution itself becomes the voltage applied to the liquid crystal, and therefore, based on the same principle as in Fig. 2 (1), the liquid crystal is activated in the region 42 where this voltage exceeds the operating threshold V of the liquid crystal. The liquid crystal does not operate in a region 41 in which it operates and does not exceed the operating threshold value V. As a result, when the polarizing plates are placed in a crossed nicol state, the liquid crystal cell exhibits a light transmission distribution as shown in FIG. 2 (2). Here, the region 41 is a light transmitting region, and the region 42 is a light blocking region, as described above. The reason why the voltage distribution shown in FIG. 3 (1) occurs by the method described here is due to the transparent electrode resistance (
This is because R1) is 10 times larger than the resistance (Ro) of the liquid crystal. That is, in this liquid crystal cell, the current flowing from the transparent electrode 9 of the lower plate 2 to the transparent electrode 10 of the grounded upper plate 3 increases as the distance from the terminal 5 increases.
Since the current is larger than that flowing in the plane of , a voltage drop as shown in .

When voltage v0 is applied to electrodes 5 and 6 in Fig. 1 and electrode 7.8 is grounded, based on the same principle, Fig. 3 (3)
A voltage distribution ■ occurs as shown below. In this case as well, the liquid crystal operates only in the region 42 in which the voltage applied to the liquid crystal exceeds the operating threshold value 1 of the liquid crystal, and exhibits a light transmission distribution as shown in FIG. 3(4).

Next, as two transparent electrodes 9 and 10, both of them are made of liquid crystal.
The aperture operation of a liquid crystal cell when a transparent electrode with a surface resistance of 0 times is used will be explained. When voltage v0 is applied to electrode 5.6 and voltages 7 and 8 are grounded, a voltage distribution as shown in FIG. 3(5) is generated. In this figure, ■ is the voltage distribution generated between the electrode ends a and b of the transparent electrode 9, and ■ is the voltage distribution generated between the electrode ends a and b of the transparent electrode 9, and
This is the voltage distribution that occurs between electrode ends c and d at zero. here,
The cell position between electrode ends a and b is taken on the horizontal axis, and the cell position between electrode ends c and d is taken on the right vertical axis. In this liquid crystal cell, the voltage applied to the liquid crystal is the difference between ■ and ■, and the potential difference distribution is concentric circles centered at the cell center, and the area exceeding the operating dark value is outside the circle centered at the cell center. This is the area of - As a result, the light transmission and overdistribution take a shape as shown in FIG. 3 (6), and a circular aperture state is formed.

Next, a liquid crystal cell was fabricated using a transparent electrode having a surface resistance 10 times the liquid crystal resistance as the transparent electrode 9 and a transparent electrode having a surface resistance equal to the liquid crystal resistance as the transparent electrode 10. When a voltage v0 was applied to the electrodes 5 and 6 and the electrodes 7 and 8 were grounded, voltage distributions ■ and ■ as shown in FIG. 3 (7) were formed. Voltage distribution■.

Since a voltage corresponding to the difference of Been formed.

Next, a transparent electrode having a surface resistance equal to the liquid crystal resistance is used as the transparent electrode 9, and a transparent electrode having a surface resistance equal to the liquid crystal resistance is used as the transparent electrode 10.
A liquid crystal cell was fabricated using a transparent electrode with twice the surface resistance. Voltage ■ on electrodes 5 and 6. was applied and the electrode 7.8 was grounded, a voltage distribution ``5'' as shown in FIG. 3(8) was formed. In this case as well, an elliptical potential difference distribution is applied to the liquid crystal as in Figure 3 (7), the light transmission distribution is as shown in Figure 3 (00), and the shape of the aperture is the same as in (8). It now has an elliptical shape with the direction of the minor axis reversed.

Furthermore, in a liquid crystal cell that shows the voltage distributions shown in Figure 3 (5), (7), and (9), when terminals 5 and 6 are grounded and voltage v0 is applied to terminals 7 and 8, a similar potential difference distribution will occur. (6), (8), and GO), respectively.

In the above aperture operation, the effective voltage ■. Changing , the voltage distribution generated within the liquid crystal cell changed, and as a result, the boundary beyond the operating darkness value of the liquid crystal moved, and the size of the aperture, that is, the aperture ratio, changed.

Next, the relationship between the resistance of the liquid crystal and the surface resistance of the transparent electrode in the liquid crystal cell according to the present invention will be explained. In FIG. 1, it is assumed that the surface resistance of the transparent electrode 10 of the upper plate 3 is sufficiently smaller than the resistance of the liquid crystal. Two transparent electrodes9. Let the resistance of the liquid crystal sandwiched by IO be Ro (Ω), and the electrode 5 of the transparent electrode 9 on the lower plate 2
．． The resistance between 6 and 6 is R.

(Ω), p is formed between the electrodes 5 and 6 of the liquid crystal cell.

FIG. 4 shows an example. Interelectrode resistance RI
When the resistance R0 of the liquid crystal and the resistance R0 of the liquid crystal were equal, that is, when K=1, a voltage distribution (2) as shown in FIG. 4(1) was formed between the electrode ends a and b of the liquid crystal cell. Also, if = 10, (2
) is formed, and when K=50, (
A voltage distribution ■ as shown in 3) was formed. As we will see, as the value of K increases, the degree of voltage drop at the center of the cell increases.The liquid crystal operates only in the region where this voltage distribution curve ■ exceeds the operating dark value VLh of the liquid crystal, so the aperture In order to operate, the voltage distribution curve must intersect with the dark value voltage.The operating threshold of the liquid crystal is determined by the liquid crystal, so the voltage distribution curve must intersect with the operating dark value of the liquid crystal. To do this, we prepared a liquid crystal cell with an appropriate value of K, and also set the voltage to be applied to the opaque electrode.
. needs to be set within an appropriate range. As can be seen from the results in FIG. 4, the value of K needs to be larger than O2l in order to perform an appropriate aperture operation.

In other words, if the value of K is less than 0.1, almost no voltage drop occurs, and therefore, ■. No matter how the value of is set, the aperture operation will not occur because it does not intersect with the liquid crystal operation threshold value ■. Furthermore, although there is no upper limit to the value of K, if K becomes infinitely large, the voltage distribution ■ will become a curve convex downward, and the voltage applied to the center of the cell will become extremely small.
The liquid crystal will not operate unless the voltage v0 applied to the electrodes is made considerably large. Therefore, ■. is within a realistic value range,
The voltage distribution curve ■ intersects the operating darkness value of the liquid crystal, and the intersection point is ■. In order to move as wide a range as possible between electrodes a and b by changing K = 1 to 100.
It is desirable that it be 0. To explain this in more detail, if K is less than 1, the applied voltage ■. It only needs to be slightly larger than the operation threshold ■, and the aperture operation will occur with a relatively small applied voltage. The size of the diaphragm, that is, the aperture ratio, changes greatly by slightly changing the aperture ratio. Therefore, when trying to accurately change the aperture ratio, the allowable range of the applied voltage, that is, the operating margin is small (and K is less than 1000). If it is large, as described above, unless (1) is considerably large, the aperture operation will not occur over the entire surface of the liquid crystal cell, which is impractical.

As mentioned above, if a liquid crystal cell is fabricated using transparent electrodes with appropriate surface resistance, aperture operation can occur simply by applying a voltage between two transparent electrodes, and the aperture ratio can also be changed arbitrarily. Understood.

Next, it will be explained with reference to FIG. 5 that various types of aperture operations can be performed based on the principle of the present invention. FIG. 5 shows a pattern of metal electrodes formed on one transparent electrode of a liquid crystal cell and the shape of the aperture when a certain voltage is applied to the metal electrodes. Here, when the surface resistance of one transparent electrode is larger than the resistance of the liquid crystal, the surface resistance of the other transparent electrode may be small, and in this case, a metal electrode on the other transparent electrode is not particularly required.

In the figure, 5 indicates a metal electrode, 41 indicates a light transmitting part in the cell window, and 42 indicates a light blocking part in the cell window.

FIG. 5(1) shows a liquid crystal cell in which one side of a rectangular cell window is in contact with an opaque electrode 5. In FIG. When a voltage corresponding to the metal electrode 5 was applied, an operation similar to that shown in FIG. 3(1) occurred, and when the polarizing plate was placed in a crossed nicol state, a band-shaped light blocking portion 42 was formed from the metal electrode side.

FIG. 5(2) shows a liquid crystal cell in which two opposing sides of the cell window are in contact with metal electrodes 5. When a voltage that forms the metal electrode 5 is applied, an operation similar to that shown in FIG. 3 (3) occurs, and a band-shaped light blocking portion 42 is formed from the two metal electrode sides, and the light transmitting portion 410 is smaller than when no voltage is applied. The area has become smaller. Figure 5 (3) shows a liquid crystal cell in which the metal electrodes in contact with the two cell windows are formed with a single electrode. It shows that an action occurs.

FIG. 5(4) shows a liquid crystal cell in which three sides of the cell window are in contact with metal electrodes 5. In this case as well, when a voltage was applied in the same manner, light blocking portions 42 were formed from the three metal electrode sides.

FIG. 5(5) shows a liquid crystal cell in which the entire periphery of the cell window is in contact with the metal electrode 5. In this case, a circular light transmitting portion 41 centered at the midpoint of the cell window was formed.

It was found that various shapes of apertures were formed in the window of the liquid crystal cell, as shown in q, depending on the pattern of the metal electrode on the cell window.

Further, in all of these, the aperture ratio was changed by changing the magnitude of the effective voltage applied to the metal electrode 5.

The liquid crystal cell shown in Fig. 5 has a square cell window, but in order to perform an aperture operation, the cell window does not necessarily have to be square; it can be rectangular, triangular, pentagonal, circular, etc. It is easy to infer that the cell window can be of any shape, and it is also clear that in this case, depending on the shape and number of metal electrodes, any type of aperture action can be achieved.

Further, although the aperture operation according to the present invention has been explained using a twisted nematic liquid crystal cell as an example, the type of liquid crystal cell is not limited to this, and the present invention can be realized in all types of liquid crystal cells. That is, the liquid crystal cells include twisted nematic cells, super twisted nematic cells, electric field controlled birefringence cells, and cholesteric cells.

Pleochroic cells (guest-hosted cells).

All types of liquid crystal cells such as dynamic scattering cells and ferroelectric liquid crystal cells are applicable to the present invention. Further, there are no restrictions on the liquid crystal material used for these cells, and any liquid crystal that operates by electric field or current can be used, such as nematic liquid crystal, nematic liquid crystal for two-frequency drive, cholesteric liquid crystal, and ferroelectric liquid crystal.

In order to perform an aperture operation using the liquid crystal cell according to the present invention, the voltage signal applied to the metal electrode may be a direct current or an alternating current, and may be a unipolar signal or a bipolar signal. You can. Furthermore, the aperture operation of the liquid crystal cell described so far can be performed constantly depending on the applied signal waveform, or can be performed instantaneously for a necessary period of time.

In order to make the content of the present invention clearer, the present invention will be explained below using specific examples.

[Example 1] Behind the liquid crystal cell shown in FIG. 1, Nesa glass with a surface resistance of 108 Ω/hole was used as the lower plate 2, and ITO glass with a surface resistance of 30 Ω/hole was used as the upper plate 3 to form a twisted nematic type. A liquid crystal cell was created. The cell dimensions were such that both the lower plate 2 and the upper plate 3 were squares with sides of 20 mm, and the cell window dimensions were such that the distances ab and cd between electrode terminals were both 10 m. Metal electrodes 5 to 8 were formed by an aluminum vapor deposition method. The spacer thickness is 6μ, and when P-type nematic liquid crystal is injected into it, two transparent electrodes 9.1
The DC resistance between 0 and 0 was 2×10′Ω. The liquid crystal cell made in this way is sandwiched between two polarizing plates so that each polarization axis matches the orientation direction of the liquid crystal, and white light is irradiated from one side of the liquid crystal cell to change the light transmission state of the cell window. observed. When a DC voltage of +6V was applied to the lower plate electrode 5 and the upper plate electrode 7.8 was grounded, a light blocking portion 42 as shown in FIG. was formed. When the voltage applied to the lower plate electrode 5 was changed while the upper plate electrodes 7 and 8 were grounded, the area of the light blocking portion was changed. When the aperture ratio is defined as the percentage of the area of the light transmitting portion to the total area of the cell window, the aperture ratio varied as shown in FIG. 7 depending on the applied voltage.

[Example 2] ゛Using the same liquid crystal cell as that produced in Example 1, +4V DC voltage was applied to the lower plate electrodes 5 and 6, and the upper plate electrodes 7 and 8
When the cell window was grounded, a light blocking portion 42 as shown in FIG. 8 was formed in the cell window, which was completely transparent when no voltage was applied. When the voltage applied to the lower plate electrode 5 was changed while the upper plate electrode 7.8 was grounded, the area of the light blocking portion was changed. The aperture ratio varied as shown in FIG. 9 depending on the applied voltage.

[Example 3] A guest-host type liquid crystal cell was fabricated using Nesa glass with a surface resistance of 2 x 10''lΩ/hole as the lower plate 2 of the liquid crystal cell, and ITO glass with a surface resistance of 30Ω/hole as the upper plate 3. The cell dimensions were the same as in Example 1, and a metal electrode 5 as shown in FIG. 5 (5) was formed on the transparent electrode of the lower plate 2 by aluminum vapor deposition. When a P-type nematic liquid crystal containing a dichroic dye was injected into the liquid crystal, the impedance between the two transparent electrodes was 6.2×10'Ω. When the cell window was observed by placing it outside the liquid crystal cell and irradiating white light from the polarizing plate side, the cell window was in a light-blocking state when no voltage was applied.

When a bipolar signal with a frequency of IKIIz and a voltage of 12V was applied to the metal electrode on the lower plate, and the electrode on the upper plate was grounded, the first
A light transmitting portion 4I as shown in FIG. 0 was formed. When the voltage amplitude or duty applied to the metal electrode was changed, the area of the light transmitting portion was changed.

Further, in contrast to the above, the exact same phenomenon was observed when a signal voltage was applied to the upper plate electrode and the lower plate metal electrode was grounded.

[Example 4] A twisted nematic liquid crystal cell was manufactured by using Nesa glass with a surface resistance of 5×10 bΩ/hole as the lower plate 2 of the liquid crystal cell, and using ITO glass with a surface resistance of 30Ω/hole as the upper plate 3 of the liquid crystal cell. The cell dimensions were the same as in Example 1, and a metal electrode 5 as shown in FIG. 5(5) was formed on the transparent electrode of the lower plate 2 by aluminum vapor deposition. The spacer thickness is 5μ, and when a nematic liquid crystal for two-frequency drive is injected into it, the impedance between the two transparent electrodes is IKII.
4X106Ω at z, 2 at 150KIIz
It was 10'Ω. The upper plate electrode is grounded, and the frequency 1 is applied to the lower plate electrode 5.

When an alternating current voltage with an amplitude of 8 cm was applied, a light blocking portion 42 as shown in FIG. 11 was formed in the cell window, which was completely transparent when no voltage was applied. Next, while applying the same voltage to the lower plate electrode, an alternating current voltage with a frequency of 150 KHz and an amplitude of 6 mm was applied to the upper plate electrode, and a donut-shaped light blocking portion 42 was formed as shown in Fig. 12. . In this example, when the voltage amplitude of IKIIZ or 150Kllz was changed, the aperture ratios in FIGS. 11 and 12 were changed.

[Example 5] As the lower plate 2 of the liquid crystal cell, the surface resistance was 1.2×105Ω/
Using Nesa glass for the mouth, the surface resistance is 30Ω as the upper plate 3.
A ferroelectric liquid crystal cell was fabricated using ITO glass. The cell dimensions were the same as in Example 1, and a metal electrode 5 as shown in FIG. 5(4) was formed on the transparent electrode of the lower plate 2 by aluminum vapor deposition.

'The spacer thickness was 2.2n, and when room temperature ferroelectric liquid crystal was injected into it, the impedance between the two transparent electrodes was 6×10'Ω at IKIIz.

The polarization axes of the two polarizing plates are orthogonal, and the polarization axis of one polarizing plate is aligned with the direction of the liquid crystal director.
When a liquid crystal cell was sandwiched between two polarizing plates, the entire cell window was completely light-blocked. When the upper plate electrode is grounded and a rectangular wave signal with a voltage of +20V and a pulse width of 1 ms is applied to the lower plate electrode 5, a light transmitting part 41 as shown in FIG. Saved unless applied. Next, apply a voltage of -20V to the lower plate electrode, and apply a pulse width of 1, 5.
When a rectangular wave signal of ms was applied, the light transmitting portion 41 shown in FIG. 13 disappeared, and the cell window became completely light-blocked.

In addition, in this embodiment, when the voltage or pulse width of the rectangular wave signal applied to the lower plate electrode is changed, the light transmitting portion 41
The area of has changed. Furthermore, also in this example,
When the relative angle between the liquid crystal cell and the two polarizing plates was shifted by 45 degrees, the light transmitting part and the light blocking part were reversed and the same behavior was exhibited.

[Example 6] Among the liquid crystal cells shown in FIG. 1, Nesa glass with a surface resistance of lXl0'Ω/hole was used as the lower plate 2, and Nesa glass with a surface resistance of 9×10'Ω/inch was used as the upper plate 3. A twisted nematic liquid crystal cell was fabricated. The cell dimensions are the same as in Example 1, the spacer thickness is 9μ, and P
When a type nematic liquid crystal was injected, the impedance between the two transparent electrodes was 2×10'Ω in IKIIZ. The upper plate electrode is grounded and the lower plate electrode is connected to the frequency I KH.
When an alternating current signal of z and voltage of 5 .mu. When the voltage applied to the lower plate electrode was changed while the upper plate electrode was grounded, the aperture ratio changed.

[Examples 7 to 12] A twisted nematic type liquid crystal cell was formed by using Nesa glass with a surface resistance of 4 x 10'Ω/hole as the lower plate 2 of the liquid crystal cell, and using ITO glass with a surface resistance of 30Ω/hole as the upper plate 3. . The cell dimensions were the same as in Example 1, and metal electrodes 5 as shown in FIGS. 15(1) to 15(6) were formed on the transparent electrode of the lower plate 2 by aluminum vapor deposition. The spacer thickness was 9 μm, and when a P-type nematic liquid crystal was injected into the spacer, the impedance between the two transparent electrodes was 8×10′Ω in l and lz. When the upper plate electrode was grounded and an AC voltage of IOV was applied to the lower plate electrode 11, the 15th
Light blocking portions 42 as shown in FIGS. (1) to (6) were formed. When the voltage amplitude or duty ratio applied to the lower plate electrode 5 was changed while the upper plate electrode was grounded, the aperture ratio was changed.

(5) As described in detail, according to the present invention, a liquid crystal cell is manufactured using transparent electrodes having a surface resistance equal to or higher than that of the liquid crystal, and a voltage is applied between the two transparent electrodes. When applied, a potential difference distribution occurred within the surface of the liquid crystal cell, so a corresponding light transmitting part and a light blocking part were formed in the cell window. Furthermore, by changing the applied voltage, the ratio of the light-transmitting part to the light-blocking part can be changed, so the aperture ratio can be freely controlled. Furthermore, by changing the shape of the metal electrode formed on the transparent electrode, it was possible to create a light transmitting part of any shape. Due to the above effects, the liquid crystal cell according to the present invention can be applied as a liquid crystal light shutter having an area modulation function to liquid crystal displays, liquid crystal printer heads, and the like. In addition, the signal wiring required to perform these operations is one for each of the two transparent electrodes, which not only simplifies the cell structure but also facilitates the formation of high-density matrices and arrays of liquid crystal cells. It has the advantage of being easy.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing the disassembled state of the liquid crystal cell according to the present invention, Fig. 2 is a diagram showing the principle of the aperture operation, and Fig. 3 is a diagram showing the voltage distribution within the liquid crystal cell and the aperture state formed at that time. Figure 4 is a diagram showing the relationship between the resistance ratio of the transparent electrode and liquid crystal and the voltage distribution formed in the liquid crystal cell, and Figure 5 is a diagram showing the shape of the metal electrode and the aperture state formed in the cell window. 6, 8, 10, 11, 12, 13, and 14 are diagrams showing the aperture states formed in the cell window in this embodiment, and FIGS. The figures are diagrams showing the relationship between the aperture ratio and the applied voltage in FIGS. 6 and 8, respectively, and FIG. 15 is a diagram showing the shape of the metal electrode and the aperture state formed in the cell window in this embodiment. 1...Liquid crystal cell, 2...Lower plate, 3...Upper plate,
4... Spacer, 5.6.7.8... Metal electrode,
9.10...Transparent electrode, 41...Light transmission part, 42
...Light blocking section. Patent applicant Nippon Telegraph and Telephone Corporation

Claims (1)

[Claims] In a liquid crystal light shutter in which a liquid crystal is sandwiched between two transparent conductive substrates having metal electrodes and a light transmission area is changed by changing the voltage applied between the two transparent conductive substrates, the resistance R_0 of the liquid crystal and the The ratio R_1/to the surface resistance R_1 of at least one of the two opposing transparent conductive substrates
A liquid crystal optical shutter characterized in that R_0 is configured to be larger than 1.