JPH02210418A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To maintain always optimum screen brightness without necessitating manual operations by executing the processing to determine a voltage for brightness adjustment by referring to a memory in accordance with a detected ambient temp. and to impress this voltage to a terminal for brightness adjustment by a microprocessor. CONSTITUTION:The ambient temp. which is integrally controlled mainly by the microprocessor 3 contg. the memory and is detected by a sensor 1 is taken via an A/D converter 2 into the microprocessor 3. The voltage for brightness adjustment is converted to an analog voltage via a D/A converter 4 and is then impressed to the terminal 6 for brightness adjustment. A data table to store the voltages for brightness adjustment necessary for obtaining the optimum brightness corresponding to the respective ambient temps. is prepd. in the microprocessor 3. The voltage for brightness adjustment is determined by referring to the data table in accordance with the ambient temp. the always optimum screen brightness is obtd. in this way regardless of the change in the ambient temp.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention (Field of Industrial Application)] The present invention relates to a liquid crystal display device that can always maintain optimal brightness regardless of ambient temperature.

(Prior Art) As is well known, a liquid crystal display has a characteristic that its brightness changes with changes in ambient temperature.

When the ambient temperature decreases, the display becomes lighter, and when the ambient temperature increases, the entire display range becomes darker, making it difficult to recognize the displayed content.

Therefore, as shown in FIG. 3, the liquid crystal display 5 is provided with a brightness adjustment terminal 6, and by applying an appropriate voltage to this brightness adjustment terminal 6, the brightness of the liquid crystal display 5 can be adjusted. can be changed.

In this bright jet adjustment, as shown in FIG. 3, a brightness adjustment volume 7 is normally connected to the power supply Vcc, and the brightness of the liquid crystal display 5 is thereby manually adjusted.

(Problem to be solved by the invention) In this way, in the conventional liquid crystal display device.

When adjusting the brightness of the screen, the brightness adjustment volume 7 must be manually operated. Therefore, if the device is installed in an environment where the ambient temperature changes frequently, the adjustment operation must be performed each time it is used. This poses a problem in that it is necessary and difficult to handle.

In addition, since the brightness of the screen must be adjusted manually by operating the brightness adjustment volume, it is not possible to select a high place for installation that is out of reach. For this reason, LED display devices, plasma display devices, etc. had no choice but to be adopted, even at the expense of heat generation and current consumption problems.

This invention was made in view of the problem in item (a) above, and its purpose is to provide a liquid crystal display that can always maintain an optimal brightness on the screen without any manual operation. The purpose of this invention is to provide a display device.

[Structure of the Invention] (Means for Solving the Problem) In order to achieve the above object, the present invention provides a temperature detection means for detecting the ambient temperature of the device, and a temperature detection means necessary for obtaining optimum brightness in the device. a memory for storing a brightness adjustment voltage corresponding to each ambient temperature; and a brightness adjustment voltage is determined by referring to the memory based on the ambient temperature detected by the temperature detection means, and this is applied to the device. The present invention is characterized by comprising: a microprocessor that executes processing for applying voltage to a brightness adjustment terminal;

(Function) According to such a configuration, the brightness adjustment voltage is determined by referring to the memory based on the ambient temperature detected by the temperature detection means,
Since the process of applying this to the brightness adjustment terminal of the device is executed by the micro 11 setter, the optimal screen brightness can be maintained at all times regardless of the ambient temperature without any manual operation. Can be done.

(Embodiment) FIG. 1 is a block diagram schematically showing the electrical hardware configuration of a liquid crystal display device according to the present invention.

As shown in the figure, this liquid crystal display device is mainly controlled by a microprocessor (μPU) 3 with a built-in display, and the ambient temperature detected by a sensor 1 is detected by an A/D converter. The brightness adjustment voltage, which will be described later, is input to the microprocessor 3 via the D/A converter 4 and then applied to the brightness adjustment terminal 6. ing.

Next, FIG. 2 shows the brightness adjustment process according to the present invention among the various processes executed by the microprocessor 3 (flowcharts 1 to 1 are schematically shown). The operation of the apparatus of this embodiment will be systematically explained with reference to the following.

In the figure, when the program is started, the microprocessor 3 reads the ambient temperature detected by the humidity sensor 1 via the A/D converter 2 (step 201).
, which is converted from analog to digital (step 202).

In order to compensate for the non-reality caused by the element characteristics of the sensor 1, input linearization processing is performed using the humidity sensor table Δ (Step 203).

As shown in the figure, a temperature sensor table A is stored in the microprocessor 3, and by referring to this table Δ, the read surrounding wet surface is corrected.

Then, based on the input data for which the linearization process has been completed, the brightness adjustment terminals necessary to obtain the optimum brightness in the liquid crystal display device are determined by referring to the data table B for the liquid crystal display device. (Step 204).

That is, as shown in the figure, the microprocessor 3 stores the brightness adjustment voltage (output data) necessary to obtain the optimum brightness in the device in correspondence with each ambient temperature (input data after compensation). A data table B to be stored is prepared, and the microprocessor 3 reads it in step 201 and corrects it in step 203.
Based on the ambient temperature, the brightness adjustment process (output data) is determined by referring to the data table B.

After that, after converting the obtained output data from digital to analog (step 205), the brightness adjustment terminal 6
That is, it is output to .

According to the above operation, when the ambient temperature changes, a new brightness adjustment voltage is successively determined in the output data creation process (step 204), and this is converted from digital to analog (step 205) to adjust the brightness. Since the light is immediately output to terminal 6 (step 206), there is no need to manually adjust the volume as in conventional devices, and optimal screen brightness can always be obtained regardless of changes in ambient temperature. .

Therefore, it becomes possible to mount the liquid crystal display device even in high places where it has been difficult to mount the device in the past, and the applications of this device can be expanded.

Furthermore, even when the device is installed in an environment where the ambient temperature changes frequently, manual brightness adjustment is no longer necessary each time it is used, which greatly improves usability.

In addition, especially in this embodiment, since the input linear rice processing (step 203) is adopted, it is possible to avoid correction variations based on the element characteristics of the temperature sensor 1 and maintain the correction accuracy at an optimal value over the entire operating temperature range. can.

[Effects of the Invention] As is clear from the above description, according to the present invention, it is possible to provide a liquid crystal display device that can always maintain a screen with optimal brightness without any manual operation. .

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the electrical hardware configuration of a liquid crystal display device according to the present invention, FIG. 2 is a flowchart showing the software configuration, and FIG. 3 is a block diagram showing the configuration of a conventional liquid crystal display device. be.

Claims (1)

[Claims] (1) Temperature detection means for detecting the ambient temperature of the device; a memory that stores brightness adjustment voltages necessary to obtain optimum brightness in the device in correspondence with each ambient temperature; and the temperature detection means A liquid crystal display comprising: a microprocessor that executes a process of determining a brightness adjustment voltage by referring to the memory based on the detected ambient temperature and applying the voltage to a brightness adjustment terminal of the device. Device.