JPH0789270B2 - Display switching control device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display switching control device, and more specifically, it divides an image to be displayed into a plurality of images and generates image data by the image data generating means. The present invention relates to a display switching control device for aligning the timing of new frames in a device visually displayed by a corresponding display device.

<Prior Art and Problems to be Solved by the Invention> There has been a conventional demand for obtaining a significantly large display image in a simulator system or the like. To satisfy such a demand, a plurality of display devices are required. In addition to arranging them side by side, a graphic display terminal is connected to each display device and the divided data corresponding to each display device is supplied from the host computer to the graphic display terminal. It

If such a configuration is adopted, since the divided data is simultaneously supplied from the host computer to each graphic display terminal, each graphic display terminal
By supplying the image data for one screen generated by the display terminal to the corresponding display device,
An image that is remarkably large as a whole can be visually displayed.

Also, the graphic display terminal is provided with a display memory having a dual plane configuration.
A configuration is adopted in which the new frame is displayed by switching the display memory after the image data for the screen is written in any of the display memories. Then, the load on the host computer is reduced by adding the data instructing the switching of the display memory to the divided data supplied to each graphic display terminal.

Therefore, each graphic display terminal generates image data based on the received divided data, and then switches the display memory based on the switching instruction data to visually display the new frame on the corresponding display device. Can be displayed.

However, since the image displayed by each display device, that is, the image data generated by each graphic display terminal is not generally the same, the time required to generate the necessary image data is different, and this result ,
Since the timing of the new frame for each display device is shifted, an unnatural image is displayed until all the display devices are in the new frame. Specifically, for example, in the case of displaying a state in which a car is moving, when the car straddles the display devices, the car may be cut off and shifted up or down, or the entire length of the car may be shortened. It becomes longer and shorter.
This kind of problem can be solved by setting the cycle of New Frame to 20Hz or more, but it is impossible at present to achieve such a cycle even with a relatively simple image, let alone in general. Since the image is often complicated, it is almost impossible to achieve the above cycle even if the processing speed of the graphic display terminal is slightly increased.

Also, by adopting the configuration in which the divided data and the switching instruction data are separately supplied by the graphic display terminal, it is possible to confirm whether or not the generation of the image data in each graphic display terminal is completed in the host computer. By supplying the switching instruction data on condition that the generation of the image data in all the graphic display terminals is completed, the timings of the new frames in all the display devices can be aligned.

However, if such a configuration is adopted, the host
After the divided data is supplied from the computer to each graphic display terminal, it is necessary to perform inquiry processing to confirm the completion of image data generation and transfer processing of switching instruction data, and not only the processing amount but also communication. Since the amount of data increases, the display speed of the entire system decreases.

<Objects of the Invention> The present invention has been made in view of the above problems,
An object of the present invention is to provide a display switching control device capable of synchronizing new frames in a plurality of display devices without impairing the display speed of the entire system.

<Means for Solving the Problems> In order to achieve the above-mentioned object, the display switching control device of the present invention is provided with a switching means that is controlled based on a drawing end signal output from the image data generating means. In addition, there are provided display instruction signal generation means that operates based on the switching states of the switching means, and blocking means that blocks the operation of each display instruction signal generation means based on the switching states of all the switching means.

However, it is preferable that the blocking means is a signal line that logically connects all the switching means.

<Operation> In the case of the display switching device having the above configuration, the image to be displayed is divided, the upper image data is generated by each of the plurality of image data generating means, and is visually displayed on the plurality of display devices. When a desired image is displayed as a whole, the corresponding switching means is controlled based on the drawing end signal output from each image data generating means, and the blocking means is controlled based on the switching states of all the switching means. The operation of the display instruction signal generating means for supplying the display instruction signal to each image data generating means may depend not only on the state of the corresponding switching means but also on the state of the blocking means that reflects the states of all the switching means. it can. That is, if only one of the image data generating means outputs the drawing end signal, the corresponding switching means operates, but the blocking means continues the blocking operation state. Therefore, the display instruction signal generating means generates the image data. The supply of a display instruction signal to the means is reliably prevented and the display of the new frame is prevented. Then, when all the image data generating means output the drawing end signal, all the switching means operate, so that the blocking operation by the blocking means is released, and all the display instruction signal generating means simultaneously correspond to the corresponding image data generating means. To the display instruction signal. As a result, all display means are switched to the new frame. Further, since the host computer only needs to supply the divided data to the image data generating means, the processing amount and the communication data amount can be suppressed to the necessary minimum.
It is possible to reliably prevent a decrease in display speed of the entire system.

When the blocking means is a signal line that logically connects all the switching means, it is not necessary to use special active elements or passive elements, and the configuration can be remarkably simplified.

<Example> Hereinafter, detailed description will be given with reference to the accompanying drawings illustrating an example.

FIG. 3 is a block diagram showing a schematic configuration of a display system to which the display switching control device of the present invention is applied. Three graphic display units are provided to the host computer (1) via the communication cable (11). Terminal (2)
And a graphic display terminal (2) for connecting three CRT display devices (3) via video signal cables (31)
Connected to. The drawing end detection terminals of all the graphic display terminals (2) are connected to each other and also to the host computer (1).

Therefore, if the divided data corresponding to each divided screen is supplied from the host computer (1) to the corresponding graphic display terminal (2), each graphic display terminal (2) will generate one screen of image data. Is generated and visually displayed on the corresponding CRT display device (3), so that a large image can be displayed as a whole.

Then, the divided data corresponding to the next frame is supplied to each graphic display terminal (2) on condition that the drawing end detection signal output from the drawing end detection unit is supplied to the host computer (1). Therefore, a large image that changes sequentially can be displayed.

FIG. 1 is a schematic block diagram showing an embodiment of the display switching control device of the present invention.
A terminal (2) receives a divided data from the host computer (1), and a pair of display memories for temporarily holding one screen of image data generated by the processor (21). (22) (23), a display switching section (24) for reading out image data from any of the display memories (22) and (23), and the image data selected by the display switching section (24) as analog data.・ Convert to data
It has a D / A converter (26) which supplies it to a CRT display device (3). Then, the signal B output from the processor (21) is supplied to the base terminal and the emitter terminal is grounded, and between the collector terminal of the switching transistor (27) and the power supply terminal of the photo coupler (28). The light emitting element (28a) and the diode (29) are connected in series. The output signal C from the light-receiving side switching element (28b) of the photo coupler (28) is supplied to the processor (21) as a new frame instruction signal. Further, the new frame synchronization signal A is output from the collector terminal of the notation switching transistor (27) through the signal line (20). The signal line (20) is drawn out from each graphic display terminal (2) and is connected to each other to form an open collector wired OR, and also to the host computer (1). ) Is also connected.

The signal B is a signal that becomes high level when the drawing process is started and becomes low level when the drawing process is completed.

The operation of the image switching control device having the above configuration is as follows.

When the divided data is transferred from the host computer (1) through the communication cable (11) to the graphic display terminal (2), the processor (21) starts the drawing process, and the signal B becomes high level. , The switching transistor (27) becomes conductive. Therefore, the new frame synchronization signal A becomes low level, and the light emitting element (28a) of the photo coupler (28) emits light, so that the signal C becomes low level.

FIG. 2 is a timing chart for explaining the operation of the three graphic display terminals (2a) (2b) (2c). More detailed description will be given with reference to these timing charts. ) Sequentially supplies the divided data (1a) (1b) (1c) to the graphic display terminals (2a) (2b) (2c), so that each signal B sequentially rises to a high level.
However, since the new frame sync signal A is wired or connected, it goes low when the signal B of the graphic display terminal (2a) rises to high level, and remains low level. Held in. Then, the drawing processing is completed in the order of the graphic display terminals (2a) (2c) (2b), and the signal B falls to the low level, but the new frame synchronization signal A is all the signals B. Remains low until all the switching transistors (27) are turned off, so that the new frame indicating signal C remains low. (21) does not output a switching instruction signal to the display switching section (24). That is, even if the process of generating the new image data for one screen is completed, the visual display based on the original image data is performed. When all the signals B fall to the low level, the new frame synchronization signal A rises to the high level, so that the new frame instruction signal C also rises to the high level and the processor (21) displays. Since the switching instruction signal to the switching unit (24) is output, visual display is performed based on the new image data for one screen. Further, since the new frame synchronization signal A is also supplied to the host computer (1), it recognizes that the drawing process is completed and transfers the divided data corresponding to the next frame. After that, by repeating the above-described series of processes, the knee frame image can be visually displayed at the same timing on all the CRT display devices (3).

However, the new frame by the new frame instruction signal C
When the frame switching timing is synchronized with the blanking timing of the CRT display device (3), it may be offset by one blanking cycle, but it is visually recognized as the exact same timing. There is no inconvenience. Also, the new frame sync signal A of the graphic display terminal (2)
Voltage level of the host computer (1)
If the voltage level for interfacing the frame synchronization signal A is the same, the diode (29) can be omitted.

As is apparent from the above description, the present invention exerts a remarkable effect by being applied to a moving image whose content changes sequentially, but is not limited to a moving image and is similarly applied to a still image. As a result, it is possible to eliminate the shift in the switching timing of the new frame due to the difference in the data amount between the divided still images.

Note that the present invention is not limited to the above-described embodiment. For example, instead of the wired OR connection of the open collector, OR gates are provided, and a photo coupler (28) is provided based on the output signal from the OR gate. ) Can be controlled, and when it is not necessary to consider the influence of noise, the photo coupler (28) is omitted, or a simple switching element is used instead of the photo coupler (28). In addition, various design changes can be made without departing from the scope of the present invention.

<Effects of the Invention> As described above, the first invention does not require the management of the host computer, and automatically displays the new frame when the drawing processing by all the image data generating means is completed. Therefore, it is possible to surely prevent the deterioration of the quality of the display image and also prevent the deterioration of the display speed.

The second invention has a unique effect that the configuration for aligning the timing of switching to the new frame can be remarkably simplified.

[Brief description of drawings]

FIG. 1 is a schematic block diagram showing an embodiment of a display switching control device of the present invention, FIG. 2 is a timing chart explaining a display switching control operation, and FIG. 3 is a display switching control device of the present invention. The block diagram which shows the schematic structure of a display system. (3) …… CRT display device, (20) …… signal line, (21) …… processor, (27) …… switching transistor, (28) …… photo coupler

Claims (2)

[Claims] 1. An image to be displayed is divided and a plurality of image data generating means (21) respectively generate image data,
In a device for displaying a desired image as a whole by visually displaying on a plurality of display devices (3), it is controlled based on a drawing end signal (B) output from each image data generating means (21). A switching means (27) for operating the display instruction signal generating means (28) that operates based on the switching state of the switching means (27) and the switching states of all the switching means (27). A display switching control device comprising: a blocking means (20) for blocking the operation of the display instruction signal generating means (28). 2. The display switching control device according to claim 1, wherein the blocking means (20) is a signal line for logically connecting all the switching means (27).