JPH027090A - Display device - Google Patents

Abstract

PURPOSE:To prevent the burning of a display device by lowering the display brightness of information after a timer's counting time when an input with a key is not detected during the timer's counting time. CONSTITUTION:In the display device, a color signal from an image display computer 1 is inputted in a brightness control circuit 2, which makes a display 3 display the information of graphic or character, etc., in high brightness. The brightness control circuit 2 possesses the timer for a certain short time and makes the timer continue counting more when the input with the key is detected during counting time. When the input with the key is not detected during counting time, in the same way, the circuit 2 lowers the display brightness of the display 3 after the timer's counting time. The brightness is automatically lowered thus during a waiting time when the device is not directly used, thereby preventing the burning of the display 3.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a display device for an image display computer used for office use, vehicle use, or other purposes.

(Conventional technology) In recent years, companies, factories, etc. have been streamlining administrative work.

Computers are making a remarkable contribution to automating manufacturing lines and streamlining design work using CAD (computer-aided design) systems.

Personal computers have also been introduced at home and in vehicles for entertainment purposes and safe driving of vehicles. Information is exchanged between such a computer system and an operator using a signal input key 1 and a display including a liquid crystal such as a CRT or a plasma.

The display of such a computer system is configured to adjust the brightness according to the environment in which it is used or individual differences, so that the display always has a high level of visibility.

FIG. 4 is a schematic diagram showing a display device of a conventional computer system, in which 1 is an image display computer that processes image display signals, 2' is a brightness control circuit, and 3 is a display (display device) that displays characters, figures, etc. ).

FIG. 5 is a circuit diagram showing details of the brightness control circuit 2 shown in FIG. 4, in which R, G, and B are color signals input from an image display computer. The signal is applied via the buffer 411 to the base of the transistor 5R via the base resistor 61I. Here, the transistor 5R operates as an emitter follower output circuit and outputs the R signal as a predetermined low impedance signal R'.

Similarly, the other G and B color signals are each buffered at 4o.
, 411. and transistors 5° and 5 through the base resistance 6°161+ of transistor 5°+51, respectively.
．． low impedance output signals G′, B
′ respectively. In addition, 71+ 7o, 7
m is the emitter resistance of transistors 51t5G+ and 511, respectively.

Further, 8 is a transistor for stabilizing the base bias power supply of the transistors 51+5a+ and 5;
9 is the base current applying resistor, and the connected variable resistor 1
By adjusting 0, the base bias of transistor 8 is changed, and the bleeder resistance (1, +ll, tzll),
The base voltage is changed according to the division ratio of (], io, 12a) and (lls, 12m), and the base resistor 6 is applied to the transistor 5R15015B, respectively.
Q, 6o, 6. are applied through transistors 1 to 5.
．． By changing the amplification degree of 5o and 5B, the R, G of the display,
Change the brightness level of the B display.

(Problem to be Solved by the Invention) However, since it is easy to change the brightness level of the display described in -, it is common to increase the display brightness to improve visibility. In addition, in order to fully and immediately perform its functions, image display computers, especially in factories and companies, are usually powered on and the display is in a display state at all times. Therefore, for example, if there is a fixed pattern such as a frame on a part of the display screen, the luminous efficiency of the light emitter in the fixed pattern part, or the phosphor in CRT, decreases due to long-term high-intensity irradiation, resulting in so-called burn-in. This causes a problem of display deterioration in which the displayed image in that area becomes dark.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, it is an object of the present invention to provide a display device that solves the problem of display burn-in.

(Means for Solving the Problems) The present invention achieves the above object by displaying information such as figures or characters at high brightness when the power is turned on, and in which the information display brightness can be changed by applying a brightness control signal. In the device,
If you have a timer for a certain period of time and detect a key input during the time count, it will continue counting the time, and similarly if no key input is detected during the time count.

This is achieved by reducing the display brightness of the information after the count time of the timer ends.

(Function) According to the present invention configured as described above, the display device displays at a high level of brightness for a certain period of time while the computer is being operated or even during the waiting time after the operation is completed. , computer operations can be performed clearly and without any problems.
Furthermore, since the brightness is automatically lowered during the standby time when the CRT is not in direct use, burn-in on the CRT can be completely prevented.

(Example) Hereinafter, the present invention will be explained using examples and drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention, and 13 is a key switch such as a brightness control switch or a signal input switch, and other symbols are the same as those in FIG. 4 or have equivalent functions. It shows things.

FIG. 2 shows a circuit diagram of the brightness control circuit 2 of FIG. 1, and FIG. 1 will be explained using this diagram.

R and G output from the image display computer 1.

B is a color signal input from the image display computer 1. For example, one of them, the R signal, is input to the buffer 4R.
A base resistor 6. is connected to the base of the transistor 511 through the base resistor 6. applied via. Here, the 1-transistor 51 operates as an emitter follower output circuit and outputs the 1 (signal) as a predetermined low-impedance signal R'.Similarly, the other G, B (W) signals are also buffered 4°+4B-' and 1- Base resistance of transistor 511+511 6°, 6
The signals are applied to the 1-transistor 5°+5B through the respective terminals B, and output as low impedance output signals G' and B', respectively. In addition, 7-. 7a, 7a are emitter resistors of transistors 5R+56g and 5g, respectively.

Further, 8 is 1- for stabilizing the base bias power supply of the transistors 5 B g 56 g and 511.
The transistor 9 changes the base bias of the transistor 8 by adjusting the variable resistor 10 connected to the base current applying resistor, and also the bleeder resistor (11R, 12R).
, (], 1a, +2o) , (+1++, 12g
), the base voltages are changed according to the division ratio of the transistors 55o+51 and their base resistors 6. ．． 6o, 6B, I-transistor 5. l, 5. ,5. The brightness level of the R, G, and B displays on the display is changed by changing the amplification degree of the display.

With a base resistor of 14 resistors connected in series to the variable resistor 10, for example, when a brightness control signal is input to the transistor 15 at the 11 L I+ (low) level, the transistor 15 is cut off, and the resistor 14 is turned off. The base bias voltage increases by the potential difference between both ends, and R, G,
The brightness level of the B signal increases.

On the other hand, when the brightness control signal is inputted to the transistor 15 at the 1H'' (high) level, the 1H transistor 15 becomes conductive, shorting the resistor 14 and the potential difference between its ends becomes O, so that the base bias voltage decreases. R, G, B
The brightness decreases. By applying the brightness control signal as described above, R, G.

It is possible to control the brightness of B, and the present invention is driven as follows.

FIG. 3 is an operation flowchart for controlling the driving operation of the display device having the configuration shown in FIG.

First, in FIG. 33, when the power of the display device is turned on, a brightness control signal ("L" level signal in the explanation with "-") is outputted (step (hereinafter referred to as S)) 1 to increase the brightness.
), the timer that counts a certain amount of time is reset (
S, ), In S3, it is determined whether the timer has timed out, and if the set time of the timer has not elapsed, the timer continues counting blindly (S,), While the timer is counting, no key input is required. It is determined whether a signal is input from the switch (S,), and if no signal is input, the timer interval (S6) elapses and the process returns to S.

When such a loop operation is repeated and a certain period of time set in the timer has elapsed, the brightness is lowered in S7. This is done by setting the brightness control signal to the 41 HII level as described above.

In this state, it is necessary to determine whether or not an input signal is applied from the key switch.
and repeats the loop operation with timer interval Ss,
If it is determined that there is a key input, SL. As a result, a brightness control signal of 44 L I+ is output to increase the brightness, and the process returns to step S2. In other words, if the (S,) key is input while the timer is counting up in this way, the process returns to S2 and starts counting again, and the display is displayed at high brightness during the key input, so it is always high brightness while operating the computer. The high brightness display changes to low brightness after a certain period of time after use.

As described above, the present invention is a computer display device that displays at high brightness only during use and for a certain period of time after use, and automatically displays at low brightness during other waiting times.

(Effects of the Invention) As explained above, the present invention provides a display device in an image display computer with a brightness control circuit, a key switch, and a timer, and improves visibility during a signal input to the computer and for a certain period of time after the operation. Since it is possible to display images at high brightness and at low brightness at other times, burn-in on the phosphor screen is prevented and the life of the display is therefore extended.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the configuration of an embodiment of the present invention, FIG. 2 is a diagram showing its main circuitry, FIG. 3 is an operation flowchart of the present invention, and FIG. 4 is a schematic diagram of a conventional display device. FIG. 5 is a diagram of the main circuit. DESCRIPTION OF SYMBOLS 1... Image display computer, 2... Brightness control circuit, 3... Display, 8... Stabilization transistor, 13... Key switch. Figure 1

Claims (1)

[Claims] A display device that displays information such as figures or characters at high brightness when the power is turned on, and whose information display brightness can be changed by applying a brightness control signal, has a timer for a certain short time, and during the time count. If a key input is detected, the time count continues, and if no key input is detected during the time count, the brightness of the information display is reduced after the timer has finished counting. display device.