JPH032941Y2 - - Google Patents

Description

[Detailed description of the invention] (a) Industrial application field The present invention relates to a video display tube device using, for example, a cathode ray tube.

(b) Prior Art As a conventional video display tube device of this type, for example, the one shown in FIG. 2 is known.

That is, an open collector type TTL buffer circuit 22 is connected to the video signal input terminal 21, and an output line 23 of this buffer circuit 22 is connected to the base of an npn type first transistor 24. The emitter of the transistor 24 is connected to ground, and the collector is connected to the cathode ray tube 26 via a second transistor 25.
The base is connected to the ground via a Zener diode 27, and the collector is connected to a resistor 28 to form a cascode-connected video amplification circuit.

(c) Problems to be Solved by the Invention Thus, in the conventional device described above, for example, unless the user consciously turns off the power switch, an image is projected on the cathode ray tube 26, so the user continues to view the cathode ray tube 26 for a long time. There were health problems such as decreased eyesight.

In view of these circumstances, the Ministry of Labor in Japan has issued guidelines regarding such video display tube devices, recommending that the eyes be rested for 10 to 15 minutes after viewing the display screen for approximately one hour.

VDT (video display tube) in conventional equipment
As a means of notifying the user of the device that one hour has passed, it is possible to use a speaker, buzzer, etc., but such a method may have an impact not only on the user but also on people around him. There are drawbacks to giving.

On the other hand, it is conceivable to use software to display, for example, the words "rest" on the cathode ray tube or to erase the image, but such a method has the disadvantage that data is damaged during data input.

(d) Means for solving the problem Therefore, the technical problem of the present invention is to solve the problem by reducing the brightness of the cathode ray tube when the bedtime has elapsed.
To provide a low-cost video display tube device that can notify only the user of the VDT device, has no loss of data during data input, has a simple circuit configuration, and is low in cost.

The technical means of the present invention to solve this technical problem is to provide a depreciation time timer and an inverter in a video display tube device in which the collector of the transistor is connected to the video display tube and the base is connected to the buffer circuit. , an inverter is connected to the output stage of the depletion time timer, and the output side of the inverter is connected between the buffer circuit and the base of the transistor.

(e) Effect According to this technical means, from the time when the depreciation time timer is set until just before time-up, the timer output is at "O" level (low level) and the inverter is in the open state, so it is normal. During operation, the brightness is normal, but when the timer timer times up, the timer output becomes "1" level (high level) and the inverter output becomes "0" level, so the brightness level of the video input signal is suppressed. By lowering the brightness of the video display tube, it is possible to notify only the user of the VDT device that the bedtime period (one hour) has elapsed, and to encourage the user to rest their eyes. .

(f) Embodiment An embodiment of the present invention will be described below in detail based on the drawings.

In Fig. 1, 1 is the input terminal for the video signal;
This input terminal 1 has an open collector type TTL.
Buffer circuit 2 is connected.

The output line 3 of this buffer circuit 2 is
connected to the base of the first npn transistor 4;
The emitter of the transistor 4 is connected to ground, and the collector is connected to a cathode ray tube 6 (also called a cathode ray tube or a picture tube), which is a video display tube, through the emitter and collector of another NPN type second transistor 5. are doing.

Further, the base of the second transistor 5 is connected to the cathode of a Zener diode 7, and the anode of this diode 7 is connected to ground, while the collector of the second transistor 5 is connected to a resistor 8 to form a cascode-connected video signal. It constitutes an amplifier circuit.

Reference numeral 9 denotes a depletion time timer having a timer set switch 10. An open collector type TTL inverter 11 is connected to the output stage of this depreciation time timer 9, and the output side of this inverter 11 is connected to a resistor 12.
It is connected between the output line 3, that is, the buffer circuit 2 and the base of the transistor 4 via the buffer circuit 2.

The illustrated embodiment is configured as described above,
The action will be explained below.

Now, when the timer set switch 10 is turned on, the sleep time timer 9 is activated and the switch 1 is turned on.
During the period from the input of 0 to just before the timer 9 times out, the output from the subtraction time timer 9 is at the "0" level.

Therefore, the "0" level signal is inverted by the inverter 11 and the output of the inverter 11 becomes "1" level, so the circuit operates normally and images (including characters) are displayed on the cathode ray tube 6 at normal brightness. be done.

When one hour has elapsed since the turning on of the depreciation time timer set switch 10 and the depreciation time timer 9 times up, the output of the timer 9 becomes "1" level, and this "1" level signal is inverted by the inverter 11. As a result, the output of the inverter 11 becomes "0" level, so the high brightness level of the video signal from the input terminal 1 is suppressed, and due to the change in grit bias of the cathode ray tube 6, the brightness decreases and the screen becomes dark. Therefore, it is possible to notify only the user that the sleeping time has elapsed and urge the user to rest his or her eyes.

(g) Effect of the idea The unique effects of the present invention are as follows.

That is, when the sleep time has elapsed, the brightness of the cathode ray tube 6 is reduced by the timer 9's time-up, and only the user of the VDT device can be notified of this, so there is no unnecessary influence on the surroundings. There is no.

Furthermore, since the method reduces the brightness of the cathode ray tube 6 and does not display characters or erase images using software, there is no loss of data during data input.

Furthermore, the circuit configuration is simple, the cost is low, and the device has great versatility.

[Brief explanation of the drawing]

FIG. 1 is an electric circuit diagram showing an embodiment of a video display tube device according to the present invention, and FIG. 2 is an electric circuit diagram showing an example of a conventional device. 2...Buffer circuit, 4...Transistor, 6
...Video display tube, 9...Sleeping time timer, 11...
...Inverter.

Claims (1)

[Scope of utility model registration request] Connect the collector of transistor 4 to video display tube 6,
In addition, in the video display tube device in which the base is connected to the buffer circuit 2, the depressing time timer 9
and an inverter 11, the inverter 11 is connected to the output stage of the depreciation time timer 9, and the output side of the inverter 11 is connected between the buffer circuit 2 and the base of the transistor 4. video display tube device.