JP2889747B2 - Display device contrast control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to contrast control of a display device used for displaying a screen of a personal computer or a word processor.
In particular, the present invention relates to contrast control suitable for a display device using liquid crystal.

[0002]

2. Description of the Related Art FIG. 3 shows the relationship between luminance and drive voltage of a selection voltage application segment and a non-selection voltage application segment of a conventionally used LCD display. The ratio of the luminance a to the luminance b of the non-selection voltage application segment (a /
b). Conventionally, a person using a personal computer or word processor has the best contrast (for example, the maximum contrast ratio)
The driving voltage is adjusted by changing the resistance value of a graduated variable resistor or the like on the front or side of the LCD display so that

[0003]

However, since the optimal contrast is different between the two gradation mode and the 16 gradation mode in the display mode of the LCD display, the variable resistance and the like are manually adjusted each time the display mode is changed. It was necessary to match the contrast. Further, since the relationship between the driving voltage and the temperature at which the optimum contrast is obtained is as shown in FIG. 4, there is a problem that the contrast must be manually adjusted depending on the environmental temperature at which the LCD display is operated. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to automatically adjust the contrast of an LCD display.

[0004]

In order to solve the problem of manually adjusting the contrast each time the gradation mode of the display device changes, a contrast control device for a display device according to the present invention manually adjusts the contrast of the display device. A manual adjustment unit for adjusting the contrast and the gradation mode of the display device.
A storage unit that stores a correction value of the drive voltage based on the relationship ; and an automatic adjustment unit that automatically adjusts the contrast of the display device according to the gradation mode based on the storage information from the storage unit. And

In order to solve the problem of manually adjusting the contrast according to the environmental temperature, a contrast control device for a display device according to the present invention comprises: a manual adjustment unit for manually adjusting the contrast of the display device; A temperature sensor for detecting the environmental temperature, and a gradation of the display device.
Drive voltage based on the relationship between mode, temperature and contrast
A storage unit that stores the correction values of the above, and an automatic adjustment unit that automatically adjusts the contrast of the display device according to the temperature detected by the temperature sensor and the gradation mode based on the storage information from the storage unit. It is characterized by having.

[0006]

Since the present invention has the above configuration, once the contrast is manually adjusted, the relationship between the contrast and various gradation modes is stored in the storage unit. , The contrast is automatically adjusted according to various gradation modes. Further, since the relationship between various temperatures, gradation modes, and contrasts is stored in the storage unit, the contrast is automatically adjusted according to the temperature and the gradation mode detected by the temperature sensor.

[0007]

FIG. 1 is a block diagram showing a first embodiment of the present invention. FIG. 2 is a block diagram showing a second embodiment of the present invention. The manual adjustment mechanism 1 in FIG. 1 is an adjustment mechanism using a variable resistor or the like so that the user can adjust the contrast to an arbitrary value. As shown in Table 1 below, the data storage circuit 2 stores correction values V _OP in advance in accordance with various gradation modes. Based on the information from the data storage circuit 2, correction data corresponding to various gradation modes is selected so as to obtain an optimum contrast, and is sent to the automatic contrast adjustment circuit 3. The voltage for driving the LCD display 5 is obtained by the following equation.

[0008]

[Table 1]

[0009]

## _EQU1 ## V _0P1 = V ₀ + V _0P + V _C

In the above formula, the automatic contrast adjusting circuit 3 adds the correction value V _0P to the constant standard driving voltage V ₀ , and further adds the driving voltage V adjusted by the manual adjusting mechanism 1.
_The driving voltage V _0P1 for actually driving the LCD by adding _C
And the LCD driver circuit 4 is operated. The LCD display control circuit 6 is a control circuit for displaying characters and pictures on the LCD, and sends the currently used gradation mode to the data storage circuit 2. In this embodiment, the correction values of the other gradation modes are determined based on the 16 gradation modes. However, since the correction values in the various gradation modes are relative, for example, the reference gradation mode may be different. Even in the 4-gradation mode, a correction value based on the mode can be obtained as shown in Table 2 below.

[0011]

[Table 2]

In the data storage circuit 2 shown in FIG. 2, the relationship between various temperatures, gradation modes, and contrasts is stored in advance as a correction value _VOPT as shown in Table 3 below. Therefore, the correction value is sent from the data storage circuit 2 to the automatic contrast adjustment circuit 3 in accordance with the environmental temperature and the gradation mode detected by the temperature sensor 7, and the contrast is automatically adjusted. The driving voltage V _0P2 for actually driving the LCD is obtained by the following equation.

[0013]

[Table 3]

[0014]

## _EQU2 ## V _0P2 = V ₀ + V _0PT + V _C

In the above equation, the automatic contrast adjusting circuit 3 adds the correction value V _0P2 to the constant standard driving voltage V ₀ , and further adds the driving voltage V adjusted by the manual adjusting mechanism 1.
_The driving voltage V _0P1 for actually driving the LCD by adding _C
And the LCD driver circuit 4 is operated. In this embodiment, the environmental temperature is measured by the temperature sensor 7, but the surface temperature of the LCD display may be measured. Since the optimum contrast often changes depending on personal preference, the information in the data storage circuit 2 may be updated every time manual adjustment is performed.

[0016]

As described above, according to the present invention, the relationship between various gradation modes and contrast or the relationship between various gradation modes and temperature and contrast is stored in the data storage circuit. Once a user of a word processor adjusts the contrast manually, the next time the user uses the screen, the screen is automatically displayed with the optimum contrast according to the gradation mode or the gradation mode and the environmental temperature. .

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a block diagram showing a second embodiment of the present invention.

FIG. 3 is a diagram showing a relationship between a contrast ratio of an LCD display and a driving voltage.

FIG. 4 is a diagram illustrating a relationship between a driving voltage and a temperature at which an optimum contrast is obtained.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Manual adjustment mechanism 2 Data storage circuit 3 Automatic contrast adjustment circuit 4 LCD driver circuit 5 LCD display 6 LCD display control circuit 7 Temperature sensor

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Claims (3)

(57) [Claims] 1. A manual adjustment unit for manually adjusting a contrast of a display device, and a contrast and a gradation of the display device.
The storage of the correction value of the drive voltage based on the relationship with the mode
And憶部, contrast control device for a display device characterized by comprising an automatic adjusting unit for automatically adjusting the contrast of the display device according to the gradation mode based on the stored information from the storage unit. 2. A manual adjustment unit for manually adjusting a contrast of a display device, a temperature sensor for detecting a display device or its environmental temperature, a gradation mode and a temperature of the display device.
The correction value of the drive voltage is recorded based on the relationship between
A storage unit that has been stored , and an automatic adjustment unit that automatically adjusts the contrast of the display device in accordance with the temperature and the gradation mode detected by the temperature sensor based on the storage information from the storage unit. Characteristic display device contrast control device. 3. The information in the storage section is transmitted to the manual adjustment section.
2. The method according to claim 1, wherein the information is updated every time the adjustment is made.
Or a contrast control device for a display device according to item 2.