JPH1138391A - Liquid crystal device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal device devised for precisely estimating the temp. distribution on a display surface of a liquid crystal panel by using pleural temp. sensors and made to operate a liquid crystal over the whole display surface within a proper operation temp. range. SOLUTION: Heaters H1 to H8 are formed on the surface of the polarizing plate 11a of the liquid crystal panel 10 out of a transparent heat generation material to heat the liquid crystal panel 10. Both air cooling fans F1, F2 are placed on the left side of the liquid crystal panel 10 to air cool. Both air cooling fans F3, F4 are placed on the right side of the liquid crystal panel 10 to air cool the liquid crystal panel 10. Plural thermosensitive elements S1 to S16 are arranged so as to be placed symmetrically along the outer periphery of the liquid crystal panel 10. A microcomputer 60 estimates the temp. of lattice like positions on the display surface of the liquid crystal panel 10 based on the outputs of respective thermosensitive elements S1 to S16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a liquid crystal device such as a liquid crystal display device using a liquid crystal panel.

[0002]

2. Description of the Related Art Conventionally, for example, a liquid crystal display device employs a liquid crystal panel. The liquid crystal panel is configured by sealing liquid crystal between both electrode substrates, and performs display under driving by a driving device.

[0003]

In the above liquid crystal display device, if the temperature of the liquid crystal of the liquid crystal panel is not within an appropriate operating temperature range, the operation of the liquid crystal deteriorates. For this reason, it is difficult to perform good display by the liquid crystal panel. In particular, when the temperature of the liquid crystal becomes lower than the temperature within an appropriate operating temperature range, the response of the liquid crystal sharply decreases due to the increase in the viscosity of the liquid crystal. As a result, good display by the liquid crystal panel becomes impossible.

In addition, when there is temperature unevenness in the display surface of the liquid crystal panel, the response of the liquid crystal partially varies, causing display unevenness. On the other hand, Japanese Patent Application Laid-Open No. 58-106
As disclosed in Japanese Patent Application Publication No. 524, the temperature of the liquid crystal panel is detected by a single temperature-sensitive element, and the temperature of the liquid crystal panel is heated by a heater based on the detected temperature, so that the temperature of the liquid crystal is adjusted to an appropriate operating temperature range. It is conceivable to control so that the temperature does not become lower than the above.

However, according to this, the temperature detection position of the liquid crystal panel is limited to the position where the temperature-sensitive element is arranged, so that it is not possible to accurately grasp the temperature unevenness in the display surface of the liquid crystal panel. Further, as disclosed in Japanese Patent Publication No. 4-46408, the temperature of the outer peripheral portion of the liquid crystal panel is detected by using a plurality of temperature sensing elements, and the input signal to the liquid crystal panel is changed based on the detected temperatures. It is conceivable to improve the display function.

However, according to this, since the temperature of the liquid crystal panel is determined only by the average value of the detected temperatures of the plurality of temperature sensing elements, it is necessary to accurately grasp the temperature unevenness over the entire display surface. Can not. In view of the above, the present invention devises a technique for accurately estimating a temperature distribution in a display surface of a liquid crystal panel by using a plurality of temperature sensors, so that the liquid crystal is spread over the entire display surface. It is an object of the present invention to provide a liquid crystal device that operates within an appropriate operating temperature range.

[0007]

In order to solve the above-mentioned problems, according to the first and second aspects of the present invention, the temperature sensor is arranged outside the display area of the liquid crystal panel along the outer periphery of the display area. The temperature of the liquid crystal panel is detected at each of the positions. Further, the temperature estimating means estimates the respective temperatures at the grid-like positions in the display area specified by the arrangement positions of the temperature sensors based on the detected temperatures of the respective temperature sensors. Then, the temperature control means controls the temperature of the liquid crystal panel based on each estimated temperature such that the temperature in the display area of the liquid crystal panel falls within a proper operating temperature range of the liquid crystal.

As a result, the liquid crystal operates within an appropriate operating temperature range over the entire display surface. as a result,
Operation with good responsiveness of the liquid crystal can be secured. Here, according to the invention described in claim 2, the liquid crystal panel is of a transmission type.
Further, the temperature control means includes a plurality of heaters made of a transparent material provided in a grid on the back surface of the liquid crystal panel, and air cooling means for air cooling the liquid crystal panel from the side.

As a result, since the heater is made transparent, the same function and effect as described in claim 1 can be achieved in the transmission type liquid crystal panel.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration of a matrix type liquid crystal display device according to the present invention. This liquid crystal display device includes a transmission type liquid crystal panel 10. As shown in FIG. 2, the liquid crystal panel 10 has two electrode substrates 11, 1
An antiferroelectric liquid crystal 20 is sealed between the two electrode substrates 11 and 12 via a seal 30 together with spacers and adhesive fine particles (not shown).

On the surfaces of the electrode substrates 11 and 12, polarizing plates 11a and 12a are adhered at crossed Nicols positions, respectively. The liquid crystal panel 10 is provided with the polarizing plate 1.
The display circuit is driven by the drive circuit 50 in a state where the light of the backlight 40 is transmitted from the side 1a. Further, as shown in FIG. 1, the liquid crystal display device includes eight heaters H1 to H8 and four air cooling fans F1 to F4.

The heaters H1 to H8 are made of ITO (Indi).
um Tin Oxide) is used to form a rectangular film on the surface of the polarizing plate 11a of the liquid crystal panel 10, and these heaters H1 to H8 are arranged on the surface of the polarizing plate 11a. As shown by 1, four sheets are arranged in two rows. Then, the heaters H1 to H8
Heats the liquid crystal panel 10 at the disposition position.

Of the air-cooling fans F1 to F4, the two air-cooling fans F1 and F2 are located on the left side of the liquid crystal panel 10 in FIG. 1, and the two air-cooling fans F1 and F2 are driven by Air-cool 10 from the left. On the other hand, both air cooling fans F3 and F4 are
And both air cooling fans F
3, F4 cools the liquid crystal panel 10 from the right side by driving.

Further, as shown in FIG. 1, the liquid crystal display device has 16 temperature-sensitive elements S1 to S16. Among these temperature sensing elements S1 to S16, the temperature sensing elements S1 to S6 are the temperature sensing elements S1 to S16, and the liquid crystal panel 10
On the other hand, it is arranged so that it is located symmetrically with the temperature sensing elements S7 to S12 at the upper and lower positions in FIG. The two temperature sensing elements S13 and S14 are located at the left and right positions in FIG.
6 are arranged symmetrically.

Here, the temperature sensing elements S1 to S6 are arranged along the upper edge of the liquid crystal panel 10 at equal intervals from each other, and the temperature sensing elements S7 to S12 are arranged at equal intervals to each other. Located along the lower edge. Then, both temperature sensing elements S2 and S8 facing each other, both temperature sensing elements S3,
S9, both thermosensitive elements S4, 10 and both thermosensitive elements S5, S11
Oppose each other via the center of both heaters H1 and H5, the center of both heaters H2 and H6, the center of both heaters H3 and H7, and the center of both heaters H4 and H8 (FIG. 1).
reference).

Further, the temperature sensing elements S1, S13, S14, S
Numerals 7 are arranged along the left edge of the liquid crystal panel 10 at equal intervals from each other, and the thermosensitive elements S6, S15, S16, S
Reference numerals 12 are arranged along the right edge of the liquid crystal panel 10 at equal intervals. The two thermosensors S13 and S15 and the two thermosensors S14 and S16 oppose each other via the center of each of the four heaters H1 to H4 and the center of each of the four heaters H5 to H8. (Figure 1
reference).

Thus, as shown in FIG. 4, the arrangement positions of the temperature sensing elements S1 to S16 and the respective center positions of the heaters H1 to H8 are coordinated on an XY orthogonal coordinate plane (hereinafter, referred to as "coordinates").
The coordinates (x, y)) are specified in a grid pattern.
This means that the position of the outer peripheral edge of the liquid crystal panel 10 and the position in the display area are specified in a grid shape by the coordinates (x, y). Note that the coordinates (x,
y) is referred to as grid coordinates (x _i , y _j ).

However, the temperature sensing elements S1 to S16 detect the temperature of each part of the outer peripheral edge of the liquid crystal panel 10 corresponding to each position. Note that these temperature sensing elements S1 to S16
For example, a thermocouple, a thermistor, a radiation thermometer, a capacitance thermometer, or the like is employed. Further, the liquid crystal display device includes a microcomputer 60. The microcomputer 60 responds to an image data signal, a vertical synchronizing signal, a horizontal synchronizing signal, and detection outputs of the temperature sensing elements S1 to S16.
The computer program is executed according to the flowchart shown in FIG. During this execution, the microcomputer 60 performs a process of estimating the temperature distribution of the display area of the liquid crystal panel 10 and a process of driving the liquid crystal panel 10. In addition,
The computer program is a microcomputer 6
0 in advance.

Here, a method of estimating the temperature grid temperature T _i , _j on the liquid crystal panel 10 will be described. LCD panel 10
In general, the two-dimensional steady-state heat conduction equation represented by the following equation 1 can be applied on the premise of the coordinates (x, y).

[0020]

(Equation 1) Here, in relation to the equation (1), first, coordinates (x, y) =
The lattice temperature T _i , _j at the lattice coordinates (x _i , y _j ) is 1
When expressed by the second derivative, the following approximate expressions of Expressions 2 and 3 can be obtained.

[0021]

(Equation 2)

[0022]

(Equation 3) In addition, the number 2 and number 3 in advance formula, h is the two grid coordinates (x _i, y _j) adjacent to each other interval (hereinafter, referred to as the lattice spacing) represents a.

Next, coordinates (x, y) = grid coordinates (x _i ,
If the lattice temperature T _i , _j at y _j ) is expressed by the second derivative, the following approximate expressions of Expressions 4 and 5 can be obtained.

[0024]

(Equation 4)

[0025]

(Equation 5) By deriving the difference equation for the two-dimensional steady-state heat conduction equation based on equations 1, 4, and 5, the following approximate equation 6 is obtained.

[0026]

## EQU6 ## T _{i + 1, j} + T _{i-1, j} + T _{i, j + 1} + T _{i, j-1} -4
T _{i, j} = 0 However, in the equation (6), a residual R _{i, j} described later is ignored. When the equation (6) is rearranged for the lattice temperatures T _i , _j , the following equation (7) is obtained.

[0027]

## EQU7 ## T _{i, j} = (T _{i + 1, j} + T _{i-1, j} + T _{i, j + 1} + T
_{i, j-1} ) / 4 Actually, in the calculation process, a residual R _{i, j} represented by the following equation (8) is generated.

[0028]

## EQU8 ## R _{i, j} = T _{i + 1, j} + T _{i-1, j} + T _{i, j + 1} + T
_{i, j-1} -4T _{i, j In} the present embodiment configured as above, when the liquid crystal display device is operated, the microcomputer 60 starts executing the computer program according to the flowchart of FIG.

In step 100 of FIG. 3, the detected temperatures of the temperature sensing elements S1 to S16 are input to the microcomputer 60 and are converted into digital temperature data. Next, in step 110, each approximate expression (see expression 1) for the lattice temperature T _i , _{j at} the 24 lattice coordinates (x _i , y _j ) is created as a simultaneous equation.

Next, in step 120, the grid temperature T _i , _{j at} each grid coordinate (x _i , y _j ) is calculated based on the above simultaneous equations, and each residual R _{i, j} is calculated by the equation (8). It is calculated based on. And step 130
In, it is determined whether or not each of the residuals R _{i, j} has converged within a predetermined allowable range.

Here, if each of the residuals R _{i, j} does not converge within the allowable range, the determination at step 130 is N
O, the computer program returns to step 120. Then, the calculation of each lattice temperature T _i , _j in this step 120 is repeated in a direction to make each residual R _{i, j} converge within the allowable range by using the difference method. Thereafter, when each of the residuals R _{i, j} converges within the allowable range, the determination in step 130 becomes YES.

Then, in step 140, the step
Latest lattice temperature T in the step 120_i,_jVariation
Is the grid coordinate (x_i, Y_j) = (X₁, Y₁) Through
(X_Four, Y ₆). Then step 1
At 50, each lattice temperature T_i,_jBut each other's variation
Are corrected to eliminate
Is done. In this case, the temperature distribution of the liquid crystal panel 10 is
It is thought to follow the distribution. Therefore, each lattice temperature T _i,
_jCase that is close to the true value (for example, the most probable average value)
Child temperature T_i,_jSo that the remaining lattice temperature T_i,_j
Is corrected.

With the above calculation, the in-plane temperature distribution of the display surface of the liquid crystal panel 10 can be estimated. After the process in step 150, in step 160, each of the control amounts is output as a control signal to at least one of both the heaters H1 to H8 and the air-cooling fans F1 to F4. Accordingly, the temperature of the display surface of the liquid crystal panel 10 is controlled so as to fall within an appropriate operating temperature range over the entire surface thereof in accordance with the driving of at least one of the heaters H1 to H8 and the air cooling fans F1 to F4. You.

In this case, each lattice temperature T _i , _j is calculated by using the approximate expression of the above equation (7) so as to converge the residual R _{i, j} within the above-mentioned allowable range. Is corrected so that the respective lattice temperatures T _i , _j approach the true value.
The in-plane temperature distribution can be accurately estimated over the entire display surface of the liquid crystal panel 10. Thereby, the liquid crystal panel 10
Is precisely controlled so that the temperature of the display surface is within an appropriate operating temperature range over the entire surface. As a result, the liquid crystal 2
Good display without display unevenness can be ensured based on the operation of 0 with good responsiveness.

Incidentally, the values obtained when the lattice temperatures T _i , _j of the respective lattice coordinates (x _i , y _j ) indicated by reference numerals a to d in FIG. 4 are estimated as described above are compared with the actually measured values. As a result, the result shown in FIG. 6 was obtained. Here, FIG.
, Plot points of the estimated grid temperatures T _i , _j are indicated by symbols a to d. Further, the measured values of the temperature at the respective grid coordinates (x _i , y _j ) indicated by the reference numerals a to d are calculated by using the solid lines La to L
Indicated by d.

According to this, it can be seen that each estimated grid temperature T _i , _j agrees very well with the measured value. In practicing the present invention, the number of the temperature-sensitive elements S1 to S16 may be changed as necessary. The greater the number of the temperature-sensitive elements, the higher the accuracy of the temperature estimation of the lattice temperatures T _i , _j .

In this case, the number of the temperature sensing elements S1 to S16 is
Without increasing, each lattice temperature T _i,_jLeast squares method
And grid coordinates (x
_i, Y_jIt is also possible to accurately estimate the temperature at the position between
Noh. In implementing the present invention, a backlight
When heat is generated in the electrodes 40 and the liquid crystal panel 10 etc.
Can be obtained by using the following approximate expression of Expression 9 instead of Expression 8
No.

[0038]

## EQU9 ## T _{i + 1, j} + T _{i-1, j} + T _{i, j + 1} + T _{i, j-1} +
(Qh ² / k) −4T _{i, j} = 0 In the equation (9), q represents the amount of heat generated by the electrodes of the liquid crystal panel 10 and the backlight 30. K represents the thermal conductivity of the liquid crystal panel 10. Also, in implementing the present invention,
The present invention is not limited to the liquid crystal display device, but may be applied to various liquid crystal devices such as a liquid crystal switch.

In practicing the present invention, the liquid crystal of the liquid crystal panel 10 is not limited to the antiferroelectric liquid crystal 20, but may be various liquid crystals such as a smectic liquid crystal such as a ferroelectric liquid crystal and a nematic liquid crystal. May be implemented. When no polarizing plate is provided, heaters H1 to H8 are attached to the back surface of the electrode substrate 11 of the liquid crystal panel 10. In the embodiment of the present invention, the liquid crystal panel is not limited to the transmission type, but may be a reflection type. In this case, the heaters H1 to H8 are provided, for example, on the rear surface of the reflective liquid crystal panel. Note that the heaters H1 to H8 need not be transparent.

Further, in practicing the present invention, the heaters H1 to H8 described in the above embodiment are connected to the liquid crystal panel 1
0 may be attached to the polarizing plate 12a on the display surface side. Also,
In practicing the present invention, a cooling air flow generator may be generally used without being limited to the air cooling fans F1 to F4. Further, the present invention is not limited to the heaters H1 to H8, and may be a hot liquid flow generator such as a heat pipe.

In implementing the present invention, the temperature-sensitive element S
Steps 1 to S16 are not limited to the outer peripheral edge of the liquid crystal panel 10, but may be arranged outside the display area of the liquid crystal panel 10 along the outer periphery of the display area.

[Brief description of the drawings]

FIG. 1 is a schematic overall configuration diagram of a liquid crystal display device according to the present invention.

FIG. 2 is a schematic sectional view of the liquid crystal panel and the backlight of FIG.

FIG. 3 is a flowchart showing an operation of the microcomputer of FIG. 1;

FIG. 4 is a schematic diagram in which grid coordinates (x _i , y _j ) in a matrix are drawn on a display surface of a liquid crystal panel.

FIG. 5 is a graph showing the results of estimation and actual measurement of lattice temperatures T _i , _j at positions indicated by reference numerals a to d in FIG.

[Explanation of sign numbers]

Reference Signs List 10: liquid crystal panel, 20: antiferroelectric liquid crystal, 50: drive circuit, 60: microcomputer, F1 to F4: air cooling fan, H1 to H8: heater, S1 to S16: temperature sensitive element.

Claims (2)

[Claims] A liquid crystal panel (1) incorporating a liquid crystal (20).
0), and a driving means (50) for driving the liquid crystal panel, wherein a plurality of temperature sensors (S1 to S1) are arranged outside the display area of the liquid crystal panel and along the outer periphery of the display area. S1
6) temperature sensors for respectively detecting the temperature of the liquid crystal panel at the arrangement positions thereof; and temperature estimation for estimating the respective temperatures at the grid-like positions in the display area based on the detected temperatures of the respective temperature sensors. Means (110 to 140); and temperature control means (H1) for controlling the temperature of the liquid crystal panel based on the estimated temperatures so that the temperature in the display area of the liquid crystal panel falls within an appropriate operating temperature range of the liquid crystal. To H8, F1 to F4). 2. The liquid crystal panel is of a transmissive type, and the temperature control means includes a plurality of heaters (H1 to H8) made of a transparent material provided in a grid on the back surface of the liquid crystal panel.
Air cooling means (F1) for air cooling the liquid crystal panel from the side.
2. The liquid crystal device according to claim 1, further comprising: F4).