JPH04284417A - Display circuit - Google Patents

Abstract

PURPOSE:To improve the visibility by outputting a display switching signal, which is made long in switching time corresponding to a rise in the driving voltage signal of a power circuit, by a microcomputer for control. CONSTITUTION:The source voltages of temperature compensating circuits 5 and 6 of a liquid crystal display unit 9 are inputted to the microcomputer 7 which performs display control and ambient temperature is detected by using an A/D converter incorporated in the microcomputer 7. Then the display switching time is varied corresponding to variation in the response of the liquid crystal with the temperature. Namely, a liquid crystal driving power source 6 outputs a high voltage at low temperature and a low voltage at high temperature and those liquid crystal driving voltages are inputted to the control microcomputer 7. Then the display switching time is made long when the high voltage is generated and short when the low voltage is generated corresponding to the response characteristic of the liquid crystal. Therefore, even if the response of the liquid crystal deteriorates owing to a drop in the outside air temperature, the display switching time is automatically adjusted to long-time timing where the visibility of each display can be secured and to short-time timing at normal outside air temperature.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display circuit for a liquid crystal display installed in, for example, an automobile.

0002

2. Description of the Related Art As a conventional display circuit of this type, there is a circuit as shown in FIG. That is, 1 is an ignition switch for a vehicle, 2 is a sensor that detects, for example, a headlamp disconnection, 3 is a stabilized power source for the liquid crystal display, and 4 is a signal that transmits a signal from the sensor 2 to a control microcomputer 7. 5 is a temperature detection thermistor for preventing variations in viewing angle characteristics due to temperature of the liquid crystal, 6 is a liquid crystal power supply for temperature compensation, 8 is a dynamic drive liquid crystal driver, and 9 is a dynamic drive liquid crystal. The control microcomputer 7 has a function of selecting a display item from an alarm signal input from an input interface and changing a display switching time from a liquid crystal drive power supply voltage.

[0003] Such a liquid crystal display uses a dynamic drive liquid crystal 9 that switches and displays various displays on the same display board at regular intervals in response to alarm signals input from various sensors 2. However, in this dynamic driving type liquid crystal, when the ambient temperature of the liquid crystal decreases, changes in viewing angle characteristics and response display performance become slow, making it difficult to perform effective multiplex display. Therefore, a temperature compensation circuit for correcting the liquid crystal drive voltage according to the ambient temperature, that is, a liquid crystal temperature detection thermistor 5 and a liquid crystal drive power supply 6 are required.

0004

[Problems to be Solved by the Invention] As described above, dynamic drive type liquid crystal displays have poor responsiveness especially at low temperatures, so it is necessary to adjust the display switching time of display alarm items to a value that is shorter than the display switching time of the display alarm items under the worst conditions of the liquid crystal. It is necessary to match the responsiveness, that is, the responsiveness at low temperatures, and for this reason, the switching time for each display is set to be long, so there is a problem that the display switching time is longer at normal temperatures.

[0005]

[Means for Solving the Problems] The present invention has been made in view of the above-mentioned problems in the prior art. An object of the present invention is to provide a display circuit that detects ambient temperature using an A/D converter incorporated in the device, and thereby changes the display switching time by changing the responsiveness of a liquid crystal due to temperature.

[0006]

[Embodiment] The present invention will be explained in detail below based on the embodiment shown in FIG. Therefore, the explanation of the same structural parts will be omitted.

That is, in this embodiment, in the same display circuit as the dynamic drive type liquid crystal display circuit shown in the conventional example, a part of the output from the liquid crystal drive power supply 6 for temperature compensation is The purpose is to input the signal to the control microcomputer 7 which includes an A/D converter.

In other words, the liquid crystal drive power supply 6 operates at a high voltage (for example, 8 V) at low temperatures and at a low voltage (for example, 4 V) at high temperatures.
By inputting these liquid crystal drive voltages to the control microcontroller 7, the display switching time on the liquid crystal display becomes longer (for example, 8 seconds) when a high voltage is generated at low temperatures, and becomes longer (e.g., 8 seconds) at high temperatures. When a certain low voltage is generated, the display switching time becomes shorter (for example, 5 seconds), and the display switching time can be automatically changed in accordance with the responsiveness of the liquid crystal.

Therefore, according to this embodiment, even when the responsiveness of the liquid crystal deteriorates (decreases) due to a drop in the outside temperature, the display switching time by the dynamically driven liquid crystal display ensures the visibility of each display. As long as possible,
In addition, since the timing is automatically adjusted to a short time at normal outside temperatures, the display is achieved with a long switching timing at low temperatures, and the display time is so short that it does not feel like it is long at normal temperatures. Therefore, a dynamic drive liquid crystal display device with excellent visibility can be provided.

0010

As described above, the present invention provides a liquid crystal display 9, a driver 8 that dynamically drives the liquid crystal display 9, and a signal for selecting a display item and switching the display according to an input signal to the driver 8. In a display circuit including a control microcomputer 7 that outputs a signal and a power supply circuit 6 that supplies the driver 8 with a drive voltage that increases as the temperature decreases, the control microcomputer 7 drives the power supply circuit 6. Since the display circuit outputs a display switching signal whose switching time is extended as the voltage signal rises, this means that when the responsiveness of the liquid crystal deteriorates (decreases) due to a drop in the outside temperature, The display switching time of the dynamically driven liquid crystal display is automatically adjusted to a long timing to ensure the visibility of each display, and to a short timing at normal outside temperatures. Since the display is achieved at the switching timing of , and the display time is so short that the display time does not feel long at normal temperatures, it is possible to provide a dynamic drive liquid crystal display device with excellent visibility.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a conventional dynamic drive display circuit.

FIG. 2 is a block diagram showing an embodiment of a dynamic drive liquid crystal display circuit according to the present invention.

[Explanation of symbols]

1: Ignition switch 2: Sensor 3
:power supply
4: Input interface 5: Thermistor for temperature detection 6: Liquid crystal power supply for temperature compensation 7: Control microcomputer 8:
Driver 9: Dynamic drive LCD

Claims (1)

[Claims] Claim 1: A liquid crystal display (9);
9); a control microcomputer (7) that outputs a display item selection signal and a display switching signal to the driver (8) according to an input signal; In the display circuit including a power supply circuit (6) that supplies a drive voltage that increases in accordance with a decrease in temperature, the control microcomputer (7) switches in response to an increase in the drive voltage signal of the power supply circuit (6). A display circuit characterized in that it outputs a display switching signal whose time is extended.