JPS6394226A - Display device for character and graphic - Google Patents

Abstract

PURPOSE:To extend the apparent life time of a light source for a liquid crystal display panel without lighting up the light source at the time of non-using of it by providing the titled device with a control circuit for applying an instruction to turn on/off the light source to a driving circuit for lighting up the light source. CONSTITUTION:The display device is constituted of the liquid crystal display panel 1, the light source 2 for transmitted illumination arranged on the back of the panel 1, the driving circuit 3 capable of setting up the ON/OFF of the light source 2, and the control circuit 4 for applying an instruction to turn on/off the light source 2 to the driving circuit 3. At the time of turning on only the light source 2 in the device, the light source 2 is kept at the OFF state, and when the circuit 4 sends a lighting instructing signal 5 to the circuit on the basis of a using start request, the circuit 3 turns on the light source 2. Consequently, the lighting time of the light source 2 is restricted only to working time, so that the life of the light source can be sharply extended.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a display device for characters and graphics, and more particularly to a display device having a light source for transmitted illumination and a liquid crystal display panel.

2. Description of the Related Art Conventionally, this type of character/figure display device does not have a control circuit 4 and a line for sending out a lighting instruction signal 5 as shown in FIG. 2 and a drive circuit 3 for driving this light source 2.
While the power of the device in which this display device is incorporated is turned on, the display device remains lit.

Therefore, since the light source 2 for transmitted illumination remains lit even when the display device is not in use, the life time of the light source 2 is determined by the total power-on time of the built-in device, and the actual operating time is also determined. The drawback was that it had to be replaced much sooner.

Problems to be Solved by the Invention The object of the present invention is to solve the above-mentioned drawback, that is, the problem that the light source for transmitted illumination is determined not by the actual operating time but by the power-on time of the device in which it is incorporated. An object of the present invention is to provide a graphic display device.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides a liquid crystal display panel, a light source for transmitted illumination disposed on the back side of the liquid crystal display panel, and a method for turning on/off the light source. This device employs a configuration consisting of a drive circuit whose state can be set, and a control circuit that instructs the drive circuit to turn on or off.

Operation Since the present invention is configured as described above, the light source is turned off when the power of the device incorporating the present display device is turned on, and upon request to start using the present display device, the control circuit sends a lighting instruction signal to the drive circuit. By sending υ, the drive circuit turns on the light source. At this time, characters and figures on the liquid crystal display panel can be read. Further, the control circuit stops sending out the lighting instruction signal and the drive circuit turns off the light source when there is a notice of end of use or when no key operation of the built-in device is performed for a certain period of time.

Therefore, there is an advantage that the lighting time of the light source is limited to the actual working time, and the life span is significantly extended.

Milk collection example Next, embodiments of the present invention will be described with reference to the drawings.

Referring to FIG. 1, which shows a block diagram of an embodiment of the present invention, the character/figure display device of the present invention includes a transmission liquid crystal panel 1, a cold cathode discharge tube illumination light source 2, a high frequency inverter, etc. a control circuit 4 that instructs the light to turn on and off, and a line that sends a blinking instruction signal 5 from the control circuit 4 to the drive circuit 3.

Next, the operation of this embodiment will be explained using FIG.

In this display device, the light source 2 is not turned on only when the built-in device is powered on. This state is defined as the initial state of the display device. In the initial state, the control circuit 4 constantly monitors whether there is a request to start using the display device. When a predetermined key (switch) on the operation panel of the built-in device (not shown) is pressed, the control circuit 4 detects this as a request to start using the display device, and sends the light source drive circuit 3 a request to start using the display device. By turning on the lighting instruction signal 5, a lighting instruction is given. In the initial state, the drive circuit 3 stops the oscillation of the high frequency inverter, and therefore the light source 2 is in an off state. When the lighting instruction signal 5 is turned on, the high frequency inverter starts oscillating, and the cold cathode tube of the light source 2 shines brightly due to the high frequency lighting. The liquid crystal display panel 1 is a transmissive type in the initial state, so even if the liquid crystal display panel itself is displaying, the display cannot be read by humans because the light source on the back is not the source, but the light source turns on. The state becomes readable by .

The control circuit 4 determines that the display device is no longer in use and turns off the lighting instruction signal 5 when there is a notification of end of use using a key on the operation panel or when no key operation is performed for a certain period of time. As a result, the drive circuit 3 stops the oscillation of the high frequency inverter, and the light source 2 turns off. Therefore, since the drive circuit 3 stops oscillation when the light source is not used, there is an advantage that the life of the light source is significantly extended.

Furthermore, although this embodiment has been described with reference to the case where the light source is a cold cathode tube, it can also be applied to cases where the light source is an incandescent lamp, an electroluminescent (EL) panel, etc. In the case of a light source that is expensive and has a short lifespan, the maintenance cost of the display device, including the labor cost for replacement and the labor cost for replacement, can be kept low, which is an even greater advantage.

Effects of the Invention As explained above, according to the present invention, the light source of the liquid crystal display panel can be turned on when not in use by providing a control circuit for instructing the light source to turn on or off in the drive circuit that turns on the light source. 5KL, it is possible to extend the apparent lifespan of the light source, that is, the lifespan can be extended at a rate that is proportional to the actual usage time of the display device itself, rather than just the power-on time of the embedded device or system. There is an effect.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of one embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Transmissive liquid crystal display panel, 2... Light source for transmissive illumination, 3... Drive circuit, 4... Control circuit for instructing to turn on/off, 5... Lighting instruction signal.謬/old

Claims (1)

[Claims] In a character/figure display device consisting of a liquid crystal display panel with a transmission amount, a light source for transmitted illumination disposed on the back side of the liquid crystal display panel, and a drive circuit that drives this light source, a lighting instruction is provided in the drive circuit. 1. A display device for characters and figures, comprising a circuit that generates a power supply voltage only when a power supply voltage is present, and a control circuit that instructs the drive circuit to turn on the light.