JPH05134618A - Display device - Google Patents

Abstract

PURPOSE:To prevent the burn of a fluorescent surface even at the time of using a CRT device over along period of time. CONSTITUTION:The display device which displays screen at a CRT 1 is provided with a video signal transmission circuit 3, a synchronizing signal transmission circuit 4, a synchronizing signal timing changing circuit 5 controlling the timing of the synchronizing signal transmitted by the synchronizing signal transmission circuit 4, and a timer 6 periodically emitting pulse signals to change the timing of the synchronizing signal. The timing of the synchronizing signal is periodically changed by the synchronizing signal timing changing circuit 5, by which the display screen is moved vertically or laterally as time passes by.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device for displaying an image on a CRT, and more particularly to a display device having a mechanism for preventing the fluorescent surface burning of a specific portion when displaying a still image.

[0002]

2. Description of the Related Art FIG. 7 shows the structure of a CRT display device. In the figure, 1 is a CRT, 2 is a CRT drive circuit, 3
Is a video signal sending circuit, and 4 is a synchronizing signal sending circuit.

When the character "A", for example, is displayed as a still image, the portion of the character "A" is irradiated with an electron beam, and the phosphor at that location is gradually deteriorated. Then, when the same still image is displayed for a long time, the fluorescent body in a specific place deteriorates and screen burn occurs.

There is a CRT display device disclosed in Japanese Patent Application No. 63-104971 as a prior invention for preventing the surface burning. The outline of the CRT display device will be described. In the apparatus, a timing adjusting circuit for changing the timing of the synchronizing signal by n / m (n and m are integers, N <M) of a character line between the synchronizing signal sending circuit and the CRT drive circuit. Is provided, and the on / off of the timing change is controlled by a flip-flop circuit. That is, the screen is moved vertically by n / m of the character line. In addition, the screen is moved every time the CRT display device is powered on.

[0005]

In the above-mentioned conventional CRT display device, the screen is moved when the power is turned on. Therefore, when the device is used for displaying a still image for a long time after the power is turned on,
As in the case where the timing adjusting circuit is not provided, there is a drawback that the fluorescent surface is burnt. The present invention solves this, and even when using a CRT device for a long time,
The purpose is to prevent fluorescent surface burning.

[0006]

FIG. 1 is a block diagram showing the principle of the present invention. In the figure, 1 is a CRT, 2 is a CRT drive circuit, 3 is a video signal transmission circuit, 4 is a synchronization signal transmission circuit, 5
Is a synchronizing signal timing changing circuit, and 6 is a timer.

The synchronizing signal timing changing circuit 5 controls the timing of the synchronizing signal sent by the synchronizing signal sending circuit 4. The timer 6 periodically outputs a pulse signal to the synchronizing signal timing changing circuit.

[0008]

The CRT drive circuit 2 visualizes the video signal on the CRT 1 while synchronizing with the sync signal. Therefore, every time the timing of the synchronizing signal is changed by the synchronizing signal timing changing circuit 5, the screen moves vertically or horizontally. The above synchronization signal timing change is
Since the periodic pulse is generated every time the timer 6 is issued regardless of the operation during power-on, the screen movement is also periodically performed. Further, it is desirable that the speed of screen movement is a speed that humans cannot perceive.

[0009]

FIG. 2 shows the relationship between a video signal and a sync signal.
When the time difference between the sync signal and the video signal changes, the screen moves vertically or horizontally. For example, when the change amount of the time difference is shorter than the horizontal scanning period with reference to the sync signal of FIG. 2, the screen moves to the left when the time difference becomes short like the sync signal and becomes long when the time difference becomes long like the sync signal. Moves to the right. Further, when the amount of change in the time difference is equal to or greater than the horizontal scanning period, it also moves in the vertical direction.
For example, when the horizontal scanning period is 60 μS and the time difference is increased by 60 μS, the screen is lowered downward by the horizontal scanning line segment.

FIG. 3 shows an embodiment (1) of the present invention. In the embodiment shown in FIG. 3, a signal delay circuit 51 for delaying the synchronizing signal is used as the synchronizing signal timing changing circuit. FIG. 4 shows an embodiment (2) of the present invention. In the embodiment shown in FIG. 4, a signal delay circuit 52 that delays a video signal is used as the synchronizing signal timing changing circuit to change the relative synchronizing signal timing. According to the embodiment shown in FIG. 3 or 4, the time difference between the video signal and the synchronization signal can be changed to move the screen in the vertical direction or the horizontal direction.

FIG. 5 shows an enlarged view of a part of the display screen.
As shown in the figure, the letter A is moved as a → b → c → d according to the embodiment. It is desirable that this moving speed be a level that humans cannot understand. For example, 1 character is 60 dots ×
The operation of the embodiment of FIG. 4 in the case of moving right → down → left → up as shown in FIG. 5 in the case of 60 dots will be described. The timer emits a pulse signal, for example, every 10 minutes, and the signal delay circuit 51 increases the delay width of the video signal by one dot each time the pulse signal is received. When this is repeated 30 times, the screen slowly moves to the right by 30 dots in 300 minutes, that is, half a character (a → b).
Next, the signal delay circuit 51 increases the delay width of the video signal by one scanning line each time it receives the pulse signal. This is 30
When repeated, the screen moves downward by 30 scanning lines (b
→ c). Contrary to (a → b), if the delay width is reduced each time a pulse signal is received, the pulse signal moves to the left (c → d). (B → c)
On the contrary, each time a pulse signal is received, if the delay width is reduced, it moves upward (d → a). By repeating the operation of a->b->c->d-> a, it is possible to prevent surface burning at a specific location.

FIG. 6 shows an embodiment of the synchronizing signal delay circuit. In the figure, 53-i is a flip-flop, 54 is a selector, 55 is a counter, and 6 is a timer. A synchronization signal is input to the D terminal of the flip-flop 53-0, and a dot clock is input to the clock terminal for horizontal movement and a horizontal frequency clock is input for vertical movement. Therefore, the flip-flop 53-i (i =
From the Q output of 0 to 7), the synchronization signal is delayed by i dots or i horizontal scanning lines and is output. Timer 6
The pulse signal is periodically output from. Counter 55
Counts 0 to 7 for each pulse signal from timer 6.
Up until the count reaches 7, then 0 from 7
Works down to. The count is input to the selector 54, and the selector 54 selects and outputs one output of the flip-flops 53-0 to 53-7 according to the count value. Therefore, the signal delay circuit delays and outputs the synchronization signal, and the delay width is set by the timer 6
1 dot or horizontal scanning line is changed for each pulse signal from.

[0013]

According to the present invention, as described above, C
Even when the RT device is used, it is possible to prevent the fluorescent surface from being burnt and to prolong the life of the CRT.

[Brief description of drawings]

FIG. 1 is a principle configuration diagram of the present invention.

FIG. 2 shows a relationship between a video signal and a sync signal.

FIG. 3 shows an embodiment (1) of the present invention.

FIG. 4 shows an embodiment (2) of the present invention.

FIG. 5 shows an enlarged view of a part of the display screen.

FIG. 6 shows an embodiment of a synchronization signal delay circuit.

FIG. 7 shows a conventional configuration.

[Explanation of symbols]

 1 CRT 2 CRT drive circuit 3 video signal sending circuit 4 sync signal sending circuit 5 sync signal timing changing circuit 6 timer 51 signal delay circuit 52 signal delay circuit

Claims (3)

[Claims] 1. A display device for displaying on a CRT (1), comprising a video signal sending circuit (3) and a synchronizing signal sending circuit (4).
A sync signal timing changing circuit (5) for controlling the timing of the sync signal sent by the sync signal sending circuit (4); and a timer (6) for periodically outputting a pulse signal to change the timing of the sync signal. And that the synchronizing signal timing changing circuit (5) moves the display screen vertically or horizontally with the passage of time by periodically changing the timing of the synchronizing signal. Characteristic display device. 2. A display device for displaying on a CRT (1), comprising a video signal sending circuit (3) and a synchronizing signal sending circuit (4).
A signal delay circuit (52) for delaying the video signal sent by the video signal sending circuit (3), and a timer (6) for periodically outputting a pulse signal to change the timing of the video signal. A display device characterized in that the signal delay circuit (52) moves the display screen vertically or horizontally as time elapses by periodically changing the delay time width of the video signal. .. 3. A display device for displaying on a CRT (1), comprising: a video signal sending circuit (3) and a sync signal sending circuit (4).
A signal delay circuit (51) for delaying the sync signal sent by the sync signal sending circuit (4), and a timer (6) for periodically issuing a pulse signal to the signal delay circuit (51). A display device characterized in that the signal delay circuit (51) moves the display screen vertically or horizontally as time elapses by periodically changing the delay time width of the synchronization signal. ..