JPH02105112A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To turn off a back light except when it is necessary for a liquid crystal display by turning off the back light when a timer means measures a time longer than a specific time and turning on the back light in the off state on detecting keying operation. CONSTITUTION:A main control part 13 supplies a reset signal 18 to a time monitoring timer 17 every time code information is sent from a keyboard device 16 to reset its clocking operation. When clocking the preset specific time, e.g. three minutes, the time monitoring timer 17 supplies a clocking end signal 19 to the main control part 13 and sends out a control signal for indicating the off operation of the back light to a back light illumination control signal 13. Therefore, when keying on a keyboard device 16 is not performed for the specific time, the back light 12 is turned off automatically. Consequently, the back light can be turned off except when necessary to prolong the life of the back light and reduce the power consumption.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a liquid crystal display device using a backlight, and more particularly to a liquid crystal display device that can further reduce the lighting time of the backlight.

[Conventional technology]

In liquid crystal display devices, a backlight is often used to ensure easy viewing of the liquid crystal. In other words, when a light emitting diode or the like is irradiated with light from the back of a liquid crystal display device,
Can make letters, symbols, etc. stand out clearly.

[Problem to be solved by the invention]

However, in conventional liquid crystal display devices, the backlight is turned on using a manual switch.

Therefore, if the backlight is left on for a long time, such as when someone forgets to turn it off, there is a drawback that the life of the backlight is shortened and the power consumption is increased unnecessarily.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a liquid crystal display device in which a backlight can be turned off except when necessary for liquid crystal display.

[Means to solve the problem]

V In the present invention, (i) a liquid crystal display section; (ii)
(iii) a keystroke detection means for detecting keystrokes on the keyboard; (iv) a clock means for measuring the time during which no keys are pressed on the keyboard; (V) a light extinguishing means for turning off the backlight when the clock means measures a time equal to or longer than a predetermined time; and (vi) a backlight in an unlit state. The liquid crystal display device is provided with a lighting means for turning on a light by detecting a key press by a key press detecting means.

That is, in the present invention, while keys are being pressed, the backlight is turned on to display characters, etc. on the liquid crystal display, while keys are pressed for a predetermined period of time or longer, such as when you leave your seat for other work. The backlight is turned off when the operation is not performed. Further, when the user starts to press a key, as when returning to the seat, the backlight is turned on and a display is performed on the liquid crystal display from the time when the key press detecting means detects the key press.

〔Example〕

The present invention will be described in detail below with reference to Examples.

FIG. 1 shows an outline of a data processing device using the liquid crystal display device of this embodiment. The liquid crystal display device includes a flat liquid crystal display section 11 that displays characters, graphics, etc. using liquid crystal. A backlight 12 is disposed in close contact with the back surface of the liquid crystal display section 11. backlight 12
The lighting is controlled by a control signal transmitted through a backlight lighting control line 14 connected to the main control unit 13, and when lighting, the transmissive liquid crystal display unit 11 is illuminated from the back side. Irradiate with uniform light. The liquid crystal display section 11 is connected to a display control circuit 15, and the display of characters, figures, etc. is controlled.

The main control section 13 supplies display data to the display control circuit 15.

The main control section 13 is also connected to a keyboard device 16 and a time monitoring timer 17. Each time a key on the keyboard device 16 is pressed, code information is sent to the main control unit 13, where predetermined data processing such as kana-kanji conversion is performed. The main control section 13 also supplies a reset signal 18 to the time monitoring timer 17 each time code information is sent from the keyboard device 16, thereby resetting this time measurement operation. The time monitoring timer I7 is configured to supply a timing end signal 19 to the main control section 13 after timing a preset predetermined time such as 3 minutes, for example. When the time measurement end signal 19 is supplied, the main control section 13 sends a control signal to the backlight lighting control line 14 to instruct the backlight to turn off. As a result, the keyboard device 16
If the keystroke is not waited for the above-mentioned predetermined time, the backlight 12 will be automatically turned off.

After the light is turned off, the main control section 13 remains in operation unless the main power source (not shown) of the liquid crystal display device is turned off. The keyboard device 16 is also ready for use, and when a key is pressed, the corresponding code information is supplied to the main control section 13. The main control unit 13 supplies a reset signal 18 to the time monitoring timer 17 at the timing when the code information is supplied to reset it. At the same time, the time monitoring timer 17 stops outputting the timing end signal 19. The main control unit 13 detects this change and sends a control signal to the backlight lighting control line 14 to instruct the backlight 12 to turn on.

As a result, the backlight 12 is turned on almost at the same time as the first key is pressed after the light is turned off, and the display contents of the liquid crystal display section 11 become visible due to the irradiation of the light beam. Thereafter, the backlight 12 will continue to be illuminated unless the key press interruption time reaches the time specified by the time monitoring timer 17. The same applies below.

〔Effect of the invention〕

As described above, according to the present invention, the backlight is turned off when no keys are pressed on the keyboard for a specified period of time, which not only extends the lifespan of the backlight and reduces power consumption, but also makes it possible to This has the effect that a switch used exclusively for lighting the light can be omitted.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a circuit configuration showing an example in which a liquid crystal display device according to an embodiment of the present invention is applied to a data processing device. 11...Liquid crystal display unit, 12...Backlight, 13...Main control unit, 16...
Keyboard device, 17... Time monitoring timer. Applicant: NEC Co., Ltd. Kofu NEC Co., Ltd. Representative: Patent attorney: Umeo Yamauchi

Claims (1)

[Scope of Claims] A liquid crystal display section, a backlight that illuminates the liquid crystal display section with light from its back surface, a keystroke detection means that detects keystrokes on the keyboard, and a timer that measures the time during which no keystrokes are made on the keyboard. a light extinguishing means for turning off the backlight when the time measuring means measures a time equal to or more than a predetermined time; and a lighting means for turning on the backlight in an off state by detecting a key press by the key press detecting means. Characteristic liquid crystal display device.