JPH07140955A - Image synchronization controller - Google Patents

Abstract

PURPOSE:To provide an image display controller outputting an image to a different display device by using a plotting processing device provided with the display synchronization control of the certain display device exclusion. CONSTITUTION:An original point detection circuit 160 detects an original point of a display picture from a display control signal of the plotting processing device 11, and initializes a horizontal synchronizing counter 161 and a vertical synchronizing counter 162. A display control signal generation circuit 163 generates a control signal to a display controller 13 according to the count values of the horizontal synchronizing counter 161 and the vertical synchronizing counter 162, and thus, the image is displayed on the display device 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image synchronization control device used in an image display control device.

[0002]

2. Description of the Related Art FIG. 4 is a diagram showing the configuration of a typical conventional image display control device. In FIG. 4, the system bus 40
The image data transferred via the drawing processing device 41 is stored in the image memory 42. On the other hand, the image data from the serial port of the image memory 42 is always CRT (chothod
e ray tube) Transferred to the display control device 43, CRT
In the display control device 43, the drawing processing device 41 is a clock generation device.
CR that outputs in phase with the clock input from 45
The CRT monitor 44 is controlled according to the T display synchronizing signal, and the CR
The image data will be displayed on the display screen of the T monitor 44.

[0003]

However, as described above, in the conventional image display control device, the synchronizing signal generating circuit for CRT display is built in the drawing processing device in advance, and the output signal thereof is CRT display. The image is displayed on the CRT monitor by sending it to the control device.
As described above, since the operation of the synchronization control circuit is fixed only for the CRT, there is a problem that it cannot be applied to display devices having different timings of synchronization signals such as liquid crystal and different resolutions. The present invention eliminates the above-mentioned drawbacks of the conventional image display control device and adds a few additional circuits to the general-purpose drawing processing device to display on the screen of a display device such as a liquid crystal display having a control different from that of the CRT. An object is to provide a possible image display control device.

[0004]

In order to achieve the above object, an image display control device of the present invention is an origin for detecting the timing at which the origin of a display screen is output based on a display control signal input from a drawing processing device. A detection circuit, a horizontal synchronization counter which is initialized by the origin detection circuit and counts the number of horizontal pixels of the display screen, and a vertical pixel of the display screen which is initialized by the origin detection circuit and uses carry of the horizontal synchronization counter. An image synchronization control device including a vertical synchronization counter that counts a number, and a display control signal generation circuit that generates an image display control signal according to the respective count numbers of the horizontal synchronization counter and the vertical synchronization counter. is there.

[0005]

According to the present invention, with the above configuration, the image display position is newly counted based on the display control signal output from the drawing processing device, and a new image synchronization control signal is generated using the count number. An image display control device capable of coping with various display devices having different controls is realized.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of an image display control device using an image synchronization control device according to a first embodiment of the present invention. In the image display control device of FIG. 1, the origin detection circuit 160,
An image synchronization control device 16 including a horizontal synchronization counter 161, a vertical synchronization counter 162, and a display control signal generation circuit 163 is connected between the drawing processing device 11 and the display display control device 13. In the image display control device configured as described above, the origin detection circuit 160 includes the drawing processing device 11,
Normally, a control signal for CRT called SYNC is input. FIG. 2 shows the waveforms of a typical SYNC signal and related signals. This SYNC signal, which is High during the image display section, becomes several display clock periods Low during the horizontal blank period during which the horizontal display lines are switched. Then, the display of the final horizontal line is completed, and during the vertical blank period until the display of the first horizontal line is started, it becomes Low for several horizontal line periods. Therefore, the origin detection circuit 160 is
The signal where the Low period is longer than the number of display clocks during the horizontal blank period is detected, and the initialization signal is used as the horizontal synchronization counter.
161 and the vertical synchronization counter 162. The horizontal sync counter 161 and the vertical sync counter 162 continue counting from the time they are initialized by the origin detection circuit 160 in accordance with the horizontal / vertical resolution and the horizontal / vertical blank period of the connected display device 14, respectively. The value is output to the display control signal generation circuit 163. The display control signal generation circuit 163 generates a control signal desired by the display display control device 13 from each count value and outputs the control signal, whereby the display device 14
The image display on the screen is realized.

In the above-described image display control device, the drawing processing device 11 and the image synchronization control device 16 operate on the same clock output from the clock generation device 15, so that the image memory 12 to the display display control device 13 are operated. The serial image data transferred to and the display control signal generated by the image synchronization control device 16 are automatically matched in phase. However, while the drawing performance in the drawing processing device 11 depends on the clock frequency from the clock generation device 15, when the display clock frequency required by the display display control device 13 is extremely slow, the image display control device with the above configuration The drawing performance may be significantly deteriorated. As a measure against this, FIG. 3 shows the configuration of the second embodiment. In this embodiment, the drawing processing device, the part that affects the drawing performance of the image memory, and the part that affects the image synchronization control device and the display device of the image display control device operate by independent clock generators. Further, in order to match the serial image data output by the image memory at the timing designated by the drawing processing device with the output timing specified by the display device, control using the field memory is performed. In FIG. 3, the origin detection circuit 360 is a drawing processing device 31.
Each counter is initialized to an asynchronous signal on the basis of a signal input from, and serial image data input to the field memory 38 is controlled. On the other hand, the display control signal generation circuit 363 controls the timing of serial image data output from the field memory 38 together with the display display control device 33 according to the value of each counter. As described above, in the image display control device of this embodiment, the initialization signal to the counter is made asynchronous and the timing conversion of the serial image data is controlled by the field memory, so that the drawing performance in the drawing processing device is not affected. Image display on the display device can be realized.

[0008]

As is apparent from the above description, according to the present invention, the display synchronization control of the conventionally fixed drawing processing device is made variable by using the additional circuit, so that various synchronization control displays are displayed. It has an effect that it can be applied to a device and can easily realize liquid crystal display control using a drawing processing device developed exclusively for CRT display.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an image display control device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing main signal waveforms in the first example of the present invention.

FIG. 3 is a configuration diagram of an image display control device according to a second embodiment of the present invention.

FIG. 4 is a configuration diagram of a conventional image display control device.

[Explanation of symbols]

10, 30, 40 ... System bus, 11, 31, 41 ... Drawing processing device, 12, 32, 42 ... Image memory, 13, 33 ... Display display control device, 14, 34 ... Display device, 15, 45 ... Clock generation Device, 16, 36 ... Image synchronization control device, 35 ... Drawing clock generation device, 37 ... Display clock generation device,
38 ... Field memory, 43 ... CRT display controller,
44 ... CRT monitor, 160, 360 ... Origin detection circuit, 16
1, 361 ... Horizontal sync counter, 162, 362 ... Vertical sync counter, 163, 363 ... Display control signal generation circuit.

Claims (2)

[Claims] 1. An origin detection circuit for detecting a timing at which a unique point on the display screen is output based on a display control signal input from a drawing processing device, and a horizontal display screen initialized by the origin detection circuit. A horizontal sync counter for counting the number of pixels, a vertical sync counter which is initialized by the origin detection circuit and counts the number of vertical pixels of the display screen by using the carry of the horizontal sync counter, the horizontal sync counter and the vertical sync. An image synchronization control device comprising a display control signal generation circuit for generating an image display control signal according to each count number of a counter. 2. The origin detection circuit detects origin output timing asynchronous with the display device, initializes the horizontal synchronization counter and the vertical synchronization counter, and controls the input of serial image data to the field memory to generate a display control signal. The image synchronization control apparatus according to claim 1, wherein the circuit is configured to control the image data output from the field memory.