JPS63274564A - Liquid crystal optical device - Google Patents

Abstract

PURPOSE:To minimize the dependence of liquid crystal layer temperature on an environmental temperature by incorporating a metallic electrode which is a heat-generating body in a liquid crystal panel, detecting its temperature to control energization with a temperature control circuit and keeping the temperature of the metallic electrode constant. CONSTITUTION:A liquid crystal light panel consists of a substrate 3 provided with a liquid crystal panel 1, a deflecting board 2 and a liquid crystal drive circuit, and a scanning electrode substrate 4 of the liquid crystal panel 1 is provided with metallic electrodes 6, 10 which are heat-generating bodies on the both sides. Both the sides are not opposed to a signal electrode substrate 7 because of the application of voltage to the sides. The heat-generating electrode 6 is allowed to be exposed to the exterior of the signal electrode substrate 7 after bending halfway, with a thermister 8 fixed with an adhesive member 9. The temperature of the heat-generating electrodes 6, 10 is detected by the thermister 8 and a temperature detecting means 35, and compared with a set temperature 36 through a comparison circuit 37. Energization of the heat- generating electrodes 6, 10 from a power supply 40 via an output part drive circuit 38 and an output 39 is controlled according to a deflection value of the compared temperature. Thus the set temperature can be reached in a short time and the dependability on an environmental temperature is reduced.

Description

[Detailed Description of the Invention] [Industrial Application Field] The liquid crystal optical device of the present invention is used in a liquid crystal printing optical device, and includes a liquid crystal panel having a metal electrode as a heating element,
The present invention also relates to a liquid crystal optical device having a temperature control circuit for a heating element equipped with a temperature detection means.

[Conventional technology]

Conventionally, LCDs have a narrow operating temperature range, so the operating temperature of the LCD is set so that the desired characteristics can be obtained at a temperature higher than the upper limit of the operating environment temperature, and a heating element is attached to the LCD panel to adjust the temperature. The temperature was controlled within the range. This will be explained below using FIG. 6. A heating element 101 is attached to a liquid crystal panel 103 via a metallic heat storage element 102. The temperature of the heat storage body 102 is detected by a thermistor 105 embedded inside the W heat body using a highly thermally conductive adhesive 104, and the temperature control circuit is operated to control the amount of current supplied to the heat generation body 1010, thereby controlling the heat storage body 102. The temperature is kept constant and the liquid crystal panel 103 is heated by thermal conduction.

[Problem that the invention seeks to solve]

However, the method shown in FIG. 6 has the following problems. 1. Since the combined heat capacity of the W heating element and the liquid crystal panel is large, the power required to maintain the temperature of the liquid crystal panel constant within the operating environment temperature range is also large. 26 Since the heat capacity is large, the thermal time constant is also long, and it takes a long time for the liquid crystal panel to reach the set temperature after the power is turned on.

3. Since the temperature control measure is a heat storage body, in low-temperature environments where there is a large difference between the heat storage body temperature and the environmental temperature, a temperature gradient occurs inside the liquid crystal panel, and the temperature of the liquid crystal layer decreases relative to the heat storage body temperature. , 49, and the r4H point of 6 or more, which causes an increase in parts costs and assembly man-hours for the heating element and heat storage element.

The purpose of the present invention is to solve these problems, reach the set temperature in a short time with less heating element power, reduce the dependence of the liquid crystal layer temperature on the environmental temperature, and maintain a constant temperature of the liquid crystal panel at low cost. The goal is to provide a liquid crystal optical device that can be maintained.

Means for Solving Problem C] The liquid crystal optical device of the present invention comprises a substrate provided with N scanning electrodes (N is an integer), a substrate provided with M signal electrodes (M is an integer), and a substrate provided with both of the above-mentioned scanning electrodes. 1 board! In a liquid crystal optical device comprising a liquid crystal layer sandwiched between the two substrates and at least one polarizing plate on the outside of the two substrates, which face each other with their poles inside, the scanning electrode of the substrate provided with the scanning electrode is metal electrodes provided on both sides; a temperature detection means that exposes a part of the metal signal electrode; and a temperature detection means provided in the exposed portion; energization is applied to the metal electrode to cause the metal electrode to generate heat; It is characterized by having a temperature control circuit that detects the temperature of the electrode, controls energization to the metal electrode, and keeps the temperature of the metal electrode constant.

[Effect]

According to the present invention, since the heating element is built inside the liquid crystal panel, it is possible to obtain a liquid crystal optical device with low power consumption, good start-up characteristics, and low environmental temperature dependence without increasing the number of parts.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. Here, we will discuss the application to liquid crystal panel temperature control when the liquid crystal panel is used as a light valve to write layer lines on a photosensitive drum.

FIG. 1 shows the configuration of the liquid crystal light valve of this embodiment.
The liquid crystal light valve consists of a liquid crystal panel 1, a polarizing plate 2, and a substrate 3 on which a liquid crystal driving circuit is mounted. The scanning electrode substrate 4 of the liquid crystal panel 1 is provided with metal electrodes 6 and 10 (hereinafter referred to as heater electrodes 8) as heating elements on both sides of the scanning electrode 5, and in order to apply a voltage to both ends, a signal electrode substrate is provided. Make sure you don't face 7. In order to attach the thermistor 8 as a temperature detection element to the heater electrode 8, the heater electrode 8 is bent in the middle and exposed to the outside of the signal electrode substrate 7. The thermistor 8 is fixed to the exposed portion of the heater electrode with an adhesive 9.

FIG. 2 shows the structure of a liquid crystal panel (FIG. 2 is a cross section taken along line A-A in FIG. 21
and includes polarizing plates 2 on both sides of the electrode substrate. The scanning electrode 5 is made up of a transparent scanning electrode 22 and an optically opaque metal scanning rod 23, and the signal electrode 7 is also made up of a transparent signal electrode 24 and a metal signal electrode 25. On the surfaces of the scanning electrode and the signal electrode, an alignment plate 26 for regularly aligning the liquid crystal composition is formed, and the surfaces are subjected to a rubbing treatment. The polarizing plates 2 are arranged so that their polarization axes are perpendicular to each other. The transparent electrodes of the scanning electrode substrate and the signal electrode substrate are formed by forming ITOI&I to a thickness of about 0.1 μm on a glass substrate by IT or sputtering. The gold electrode on the transparent 11 layer contains approximately 0.3 nickel (hereinafter referred to as Ni).
After plating to a thickness of μm, unnecessary parts are removed by etching. Since the heater electrode 6 is on the scanning electrode substrate, it can be formed in the same process as the scanning electrode 5. This has the advantage that by incorporating the shape of the heater electrode into a photomask for creating the scanning electrode substrate, the heater electrode can be obtained simply by inserting it into the manufacturing process of the liquid crystal panel.

FIG. 3 shows a diagram of the electrode pattern of the liquid crystal panel.

The liquid crystal light valve of this embodiment has 12 microshafts 30 per 1 mm for a total of 240 microshafts in order to obtain high resolution.
0 pieces are arranged. However, as it is, 2000 signal electrodes are required to drive the microshafter 30, which is undesirable because it increases the number of steps and costs in terms of mounting and panel manufacturing. Therefore, in this embodiment, by setting the number of time divisions to 3, there are 3 scanning electrodes and 800 signal 1 poles. The portion of the microshaft 30 of the scanning electrodes 22 and 23 has only the transparent scanning type t122, and the shaded area is covered with the metal scanning electrode 23. The signal TR pole has a metal signal F! on a part of the transparent signal electrode 24. A pole 25 is provided.

If this metal electrode is not present, can it be scanned? ! When the pole and signal electrode are overlapped, light constantly leaking from the gap between the scanning electrode and the heater electrode becomes a factor that reduces the contrast ratio of the transmitted light of the microshaft. Therefore, a part of the signal electrode was masked with a metal electrode to minimize the area of the light leakage portion 31, and it was possible to suppress the light leakage portion 31 to a level that poses no problem in practice. In addition, by making all the signal electrodes transparent except for the metal electrodes 25, the alignment margin when combined with the scanning m-pole substrate 4 can be increased both in the vertical and horizontal directions, and the yield during assembly is improved. In this embodiment, the number of time divisions is three, but the number of time divisions can be arbitrarily selected according to the characteristics of the liquid crystal.

FIG. 4 is a detailed view of the mounting portion of the thermistor 8 of the heater electric tie. The heater ff electrode 6 is equipped with a thermistor 8, etc., which is a temperature detection means for temperature control.
In this example, the signal 1! near the center of the panel! An exposed portion 32 is provided on the heater on the opposite side from the pole extraction portion. The heat dew portion 32 is designed so that the electrode width is the same as the M pole width WI of the straight portion of the heater electrode 6. However, since the heater exposed portion 32 is provided by partially bending one side of the heater exposed portion e, a difference occurs in the length of the two heater electrodes, and a difference in resistance value occurs between the two heater electrodes. Therefore, in this example, by changing the widths of the two heater electrodes to W, , W, it was possible to make the resistance values of the two heater electrodes almost equal. The resistance value of the heater electrode 6 is R=PyoXL/
It is calculated from the formula W. Here, R is the resistance value [Ω],
P, is 1! The sheet resistance of the rod material [Ω/mouth], L is the electrode length (m), and W is the electrode width (m). The sheet resistance is determined by the thickness and volume resistance of the electrode material, but in this example Here, a two-layer structure of ITO and Ni is used as the electrode material, and the thickness of ITO is 0. Iμms Ni is 0.3μ
By setting the sheet resistance to m, a sheet resistance of 1.70/mouth was obtained. The length of the heater electrode 6 is the length of the straight part by 2.
The length is 13 mm 1 plus the length 2X1 required to bend the heater. 1 is a high width WI of 3
．． By setting E to 35 mm, it becomes 1 to 3 mm, and L
I=216mm. The resistance value of the heater electrode 6 is 10
0.6Ω was obtained. In order to make the resistance value of the heater electrode 10 equal to the resistance value 6, the above formula is changed to W=P x X
Converting to L/R, substituting 100.6Ω for R and L=213mm, W was obtained as 3.8mm.

For the thermistor 8, an epoxy resin molded Y chip thermistor with a small thermal time constant was used, and fe-tt was performed using an epoxy adhesive 9 with relatively high thermal conductivity. In this embodiment, Ni is used as the heater electrode, but chromium, gold, or the like can also function as a heater. Further, the sheet resistance can be obtained as follows: pt=o, t~50Ω/port by appropriately selecting the electrode material and electrode thickness (0.1 to 0.5 μm) in accordance with the resistance value required for the heater electrode. Although a thermistor was used as the detection means, thermocouples, semiconductor temperature sensors, etc. can also be used. Furthermore, although the heater is exposed at the center of the liquid crystal panel as the mounting position of the temperature sensor, the temperature can also be similarly detected near the electrode base at the end of the heater.

FIG. 5 shows the configuration of the temperature control circuit in this embodiment. Temperature is converted into an electrical signal by the temperature detection means 35. On the other hand, the temperature setting means 36 generates a reference voltage signal that is sufficient to set the desired temperature. Temperature detection means 35
The signals outputted from the temperature detection means 36 are input to the comparison circuit 37, where a comparison operation is performed, and the signals are outputted from the output section drive circuit 3.
Send the results to 8. In the output section drive circuit 38, the output circuit 3
The signal is amplified to drive the output circuit 39, thereby causing the heater 6.10 to generate heat. power supply 4
0 supplies 1 to each part of the control circuit. in particular,
The temperature detection means is composed of a resistor 41 and the thermistor 8. The temperature setting means is composed of a resistor 42 and a temperature setting variable resistor 43, and the resistors 41, 42 . The thermistor 8 and variable resistor 43 constitute a bridge.

The temperature detection signal 51 and the temperature setting signal 52 are sent to the comparator 48.
If the temperature detection signal 51 is higher than the temperature setting signal 52 (the heater temperature is lower than the set temperature), the comparator 48
The output becomes Low level. The output drive circuit 38 and the output circuit 38 are obtained by connecting PNP transistors 49 and 50 in Darlington, so that the comparator output is Low.
At W level, transistors 49 and 50 are turned on, and heater 6 is turned on.
．． Current flows through 10, generating heat. The heater 6 and thermistor 8 are thermally coupled, and when the heater heats up and the temperature detection signal 51 becomes lower than the temperature setting signal 52 (the heater temperature is higher than the setting temperature), the comparator 48 output becomes H.
igr level and transistor 49.50 is 0FFL
, the heater temperature decreases. In this way, by comparing the temperature detection signal and temperature setting signal, the transistor's 0N10F
In this embodiment, the temperature of the heater 6.10 can be kept constant by controlling the heater voltage pi6.
By connecting two 10 in parallel, the heater electrode resistance was 50Ω, and the applied voltage V was 25V, a heater power of 12.5W was obtained. In addition, the temperature rift pull in the microshaft part is 5°C to 35°C when the environmental temperature is 3°C1.
The temperature change was 2°C, and a practically sufficient performance was obtained. Il! It took about 30 seconds for the micro-shutter section to reach the set temperature immediately after the large amount of power was turned on. In the conventional method of heating a liquid crystal panel by attaching a heating element to a heat storage element, it took 90 seconds to reach the set temperature with the heating element's heater power of 36W. The effects are obvious. The environmental temperature dependence was also reduced to 2°C according to the present invention, whereas it was 4°C in the conventional technology. In terms of cost, the liquid crystal panel itself has a built-in heater, which eliminates the need for an external heating element or heat storage plate, making it possible to reduce component costs and assembly man-hours. In the above embodiments, a liquid crystal panel may be used in which a single polarizing plate is used and a dye is contained in the liquid crystal. Further, as a temperature control method, proportional control, PWM control, etc. can also be applied.

〔Effect of the invention〕

As described above, according to the present invention, the set temperature can be reached in a short time with less heating element power, the dependence of the liquid crystal layer temperature on the environmental temperature is small, and the temperature of the liquid crystal panel can be controlled at low cost. This makes it possible to achieve the effect of controlling the temperature of the liquid crystal panel.

[Brief explanation of drawings]

Figure 1 is a diagram showing the pattern of the liquid crystal panel used in the liquid crystal optical device of the present invention, Figure 1.4 is a diagram showing details of the thermistor attachment part of the heater electrode, and Figure 5 (a) (
b) is a diagram showing the configuration of a temperature control circuit, and FIG. 6 is a diagram showing the configuration of a conventional liquid crystal panel. 1...Liquid crystal panel 2...Polarizing plate 3...Substrate mounting liquid crystal drive circuit 4...Scanning type PI board 5...Scanning electrode 6.10...Heater electrode 7...Signal Electrode substrate 8...Thermistor 9...More than contact material Applicant: Seiko Epun Co., Ltd., -1-6.
10. ' Heater Geo Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] A substrate equipped with N scanning electrodes (N is an integer), a substrate equipped with M signal electrodes (M is an integer), the two substrates facing each other with the electrodes inside, and sandwiched between the two substrates. In a liquid crystal optical device including at least one polarizing plate on the outside of a liquid crystal layer and both substrates, a metal electrode provided on both sides of the scanning electrode of the substrate provided with the scanning electrode, and a part of the metal electrode being exposed. The temperature detecting means provided at the exposed portion energizes the metal electrode to generate heat, the temperature detecting means detects the temperature of the metal electrode, and the energization to the metal electrode is controlled. , a liquid crystal optical device comprising a temperature control circuit that keeps the temperature of the metal electrode constant.