JPH0667159A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To automatically change the luminance of a display screen caused by the change of ambient illuminance. CONSTITUTION:This device is provided with an illuminance detection part 1 detecting the ambient illuminance, converting illuminance information into an electrical signal and outputting the signal, a manual adjusting part 2 changing the electrical signal by manual operation and outputting it, a luminance control part 3 controlling the luminance of a liquid crystal display part 4 according to the electrical signal from the detection part 1 and the adjusting part 2, and the liquid crystal display part consisting of a liquid crystal display element and a backlight.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device which obtains high brightness and contrast by a backlight.

[0002]

2. Description of the Related Art Since a conventional liquid crystal display device does not have a light source such as a backlight, there are problems that it is difficult to see in a dark place and the contrast is small.

Therefore, recently, a liquid crystal display device having a backlight such as a cold cathode tube or a hot cathode tube has become common. This type of liquid crystal display device has a system in which a change in brightness or contrast due to ambient illuminance and temperature is manually adjusted.

[0004]

The above-mentioned conventional liquid crystal display device does not have a function of automatically adjusting the brightness which fluctuates due to changes in ambient illuminance and temperature.
There is a drawback in that the adjustment work of manually increasing the brightness when the ambient illuminance is low and decreasing the brightness when the ambient illuminance is high is disadvantageous.

[0005]

A liquid crystal display device according to the present invention includes an illuminance detector for detecting ambient illuminance, converting the illuminance into an electric signal and outputting the electric signal, and variably outputting the electric signal by a manual operation. And a brightness control unit that outputs illuminance information for changing the brightness according to signals from the illuminance detection unit and the manual adjustment unit, and a liquid crystal display unit that changes the brightness of the display screen according to the information. .

Further, the liquid crystal display device of the present invention includes a temperature detecting section for detecting an ambient temperature, converting the temperature into an electric signal and outputting the electric signal, and a manual adjusting section for changing and outputting the electric signal by a manual operation. A contrast adjusting section for outputting contrast information for changing the contrast in accordance with signals from the temperature detecting section and the manual adjusting section; and a liquid crystal display section for changing the contrast of the display screen by the contrast information.

[0007]

The present invention will be described below with reference to the drawings. 1 is a block diagram of a liquid crystal display device according to a first embodiment of the present invention.

The illuminance detector 1 detects the illuminance of the surroundings and outputs an electric signal according to the illuminance. The manual adjustment unit 2 manually changes the electric signal. The brightness control unit 3 converts the electric signals of the illuminance detection unit 1 and the manual adjustment unit 2 into a signal for changing the brightness of the liquid crystal display device. The brightness of the liquid crystal display unit 4 is changed under the control of the brightness control unit 3.

The operation of the liquid crystal display device configured as described above will be described. First, the illuminance detection unit 1 detects the ambient illuminance using an illuminance sensor or the like. The detected illuminance information is converted into, for example, a 4-bit binary signal and output to the brightness control unit 3. Here, 0000 is the minimum illuminance value and 1111 is the maximum value.

The brightness control section 3 outputs the brightness information, which is the optimum brightness, to the liquid crystal display section 4 according to a reference table prepared in advance for the inputted illuminance information. Here, in the reference table, when the illuminance is 0000, 1111 (maximum luminance) and 11
When it is 11, the data that is 0000 (minimum luminance) is stored. The liquid crystal display unit 4 displays at the brightness designated by the brightness control unit 3.

With this arrangement, when the illuminance is low and the brightness is low, the brightness is automatically adjusted in the direction of increasing the brightness. When the illuminance is high and the brightness is high, the brightness is automatically adjusted in the direction of decreasing the brightness. The optimum value of the reference table when converting the illuminance information into the brightness information depends on the liquid crystal, the backlight, and the like used. Further, since the optimum value of the brightness may vary depending on the subjectivity of the operator, the manual adjustment unit 2 is also prepared so that the adjustment can be performed by the manual operation.

FIG. 2 is a block diagram of a liquid crystal display device according to a second embodiment of the present invention.

The temperature detector 11 detects the ambient temperature and outputs an electric signal according to the temperature. The manual adjustment unit 12 manually changes the electric signal. The contrast control unit 13 sends the electric signals of the temperature detection unit 11 and the manual adjustment unit 12 to the liquid crystal display unit 1.
4 is converted into a variable signal. The contrast of the liquid crystal display unit 14 is changed by the control of the contrast control unit 13.

The operation of the liquid crystal display device configured as described above will be described. First, the temperature detector 11 detects the ambient temperature using a temperature sensor or the like. The detected temperature information is converted into, for example, a 4-bit binary signal and output to the contrast control unit 3. Where 0000 is the minimum temperature value, 111
1 is the maximum value. The contrast control unit 13 uses the reference table prepared in advance as input temperature information to display the optimum contrast information on the liquid crystal display unit 14.
Output to. Here, in the reference table, when the temperature is 000, 1111 (maximum contrast), and when 1111 is 0,
Data of 000 (low contrast) is stored. The liquid crystal display unit 14 displays with the contrast instructed by the contrast control unit 13.

With this configuration, when the temperature is high and the contrast is low, the contrast is automatically adjusted in the direction of increasing the contrast. Further, when the temperature is high and the contrast is high, the contrast is automatically adjusted in the direction of decreasing the contrast. In addition,
The optimum value of the reference table when converting the temperature information to the contrast information varies depending on the liquid crystal, the backlight, etc. used. Since the optimum contrast value may vary depending on the subjectivity of the operator, a manual adjustment unit 12 is also prepared so that manual adjustment can be performed.

In the above description, the manual adjusting unit is used as the present embodiment, but the present invention is not limited to this, and the manual adjusting unit can be deleted, and the same effect can be obtained.

[0017]

As described above, according to the liquid crystal display device of the present invention, it is possible to automatically adjust the change of the brightness or the contrast due to the change of the ambient illuminance and the temperature.

[Brief description of 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.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Illuminance detection unit 2, 12 Manual adjustment unit 3 Brightness control unit 4, 14 Liquid crystal display unit 11 Temperature detection unit 13 Contrast control unit

Claims (2)

[Claims] 1. An illuminance detection unit that detects ambient illuminance and converts the illuminance into an electric signal and outputs the electric signal, a manual adjustment unit that variably outputs the electric signal by a manual operation, the illuminance detection unit and a manual operation. A liquid crystal display device comprising: a brightness control unit that outputs illuminance information for changing brightness according to a signal from an adjustment unit; and a liquid crystal display unit that changes brightness of a display screen according to the information. 2. A temperature detecting section for detecting the ambient temperature and converting the temperature into an electric signal and outputting the electric signal, a manual adjusting section for changing and outputting the electric signal by a manual operation, the temperature detecting section and the manual operation. A liquid crystal display device comprising: a contrast adjustment unit that outputs contrast information for changing the contrast according to a signal from the adjustment unit; and a liquid crystal display unit that changes the contrast of a display screen according to the contrast information.