JPS62239190A - Display controller - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an automatic image position adjustment circuit in a display device having a CRT separate signal interface.

More specifically, in a display device having a CRT separate signal interface, the present invention detects which part of an incoming video signal is not being displayed, and increases or decreases the vertical and horizontal pack pouches of the display device. ,
The optimum display area is obtained by -1.

[Conventional technology]

Conventionally, CRT monitors for displaying characters and graphics have a display area wider than the image area of separate signals sent from a personal computer or the like. However, when trying to create a display device with a CRT-compatible interface using a liquid crystal display, Buchsma display, EL display, etc., there is no problem as long as the display area is wider than the image area like a CRT monitor, but these displays Because bodies are expensive, they often have a display area that is the same size as the image area.

In such display devices, the position of the display area is usually aligned with the image position of the separate signal sent in advance, or manually aligned.

[Problem that the invention seeks to solve]

However, the image area for the synchronization signal is IIA@
There are also differences depending on the software of the sending device. Furthermore, even when operating with the same software, the image area may move depending on the situation. If these image areas move, a display device that has a display area only the same size as the image area may lose display unless the display area is adjusted again to the moved image area. It is troublesome to perform this operation manually.

SUMMARY OF THE INVENTION In order to solve these conventional problems, it is an object of the present invention to provide a display device that detects video data that does not fit into the display area and automatically adjusts the position of the display area.

[Means for solving problems]

The display control circuit of the present invention is characterized by comprising a circuit that detects video data that does not fit into the display area and video data at the edges of the display area, and a CPU that reads the data and adjusts the vertical and horizontal back porch positions. The display area will be automatically adjusted to the optimal position.

〔Example〕

The present invention will be explained in detail below.

FIG. 1 is a circuit diagram showing an embodiment of the present invention.
Output flags such as V1 to V4. The vertical back porch of the display screen is set by the CPU 7.

FVl is a flag indicating that the display screen is in the vertical back porch period, FF2 is a flag indicating that it is the top line period of the display screen, and FF3 is a flag indicating that it is the bottom line period of the display screen. , FF4 is a flag indicating that the display screen is in the vertical front porch period, 0 column counter 2) Isc 9 and DCK101
As a reference, flags such as FH1 to FH4 shown in FIG. 2 are output. The horizontal back porch of the display screen is set by the CPU 3. FHI is a flag indicating that it is the horizontal back porch period of the display screen, FF2 is a flag indicating that it is the leftmost prison period of the display screen, and FF3 is a flag that indicates that the ant on the display screen is also the right prison period. The flag FF4 is a flag indicating that it is the horizontal front porch period of the display screen.

The input video signal VD11 is FV1-4, FH1-4
and JK-FF by logically ANDing them with AND gate 3.
4 is input to J1 to J8. Since all inputs to JK-FF3 are w L I, JK-FF3 operates as υ only OFF at startup.0 If video data 11 exists during the period when each flag is set, bit 12 corresponding to that flag is stand.

At the beginning of an image frame, the contents of JK-FF3 are latched into the subsequent D-FF5, and the contents of JK-FF3 are cleared.

By reading the contents of D-FF5, CPU7
You can know the position information around the display screen of the video signal being sent. The CPU 7 can adjust the screen to an appropriate position by setting the vertical and horizontal back porch values based on this information.

To explain in more detail, the width of the signal of the flag FV1 is adjusted by the CPU 7 setting a numerical value in the row counter 1. Flag FV1 counts the number of ISO falls (after vSC was started).

What the CPU 7 sets is only the counter value related to this E''/1, and since the period of the vertical synchronization signal and the vertical display period are constant, by determining FF1, other FF
2, FF3, and FF4 are also automatically determined.

The JK input of JK-FF4 is high because the video data 10 is from the real screen 200 as shown in FIG.
This is the case when 0 exists above.

In this case, as is clear from FIG. 1, since the video signal 11 and flag FV1 are input to the AND gate,
When the JK input of JK-FF4 goes high and one vertical period ends, the edge detection circuit 6 detects the edge of the SC signal 8, thereby causing the outputs Q1 to Q8 of JK-FF4 to become latched and this state is C
The CPU 7 reads the flag FV.
The value of 1 is adjusted to correct the deviation between the video data 100 and the real screen 200. As a correction method, for example, a control such as decreasing the value set in the row counter 1 one by one until the Q1 output of the latch 5 becomes low can be considered.

On the other hand, if the Q4 output of latch 5 is high, it means that the video data 100 is shifted downward compared to the actual screen 200, so increase the value set in the row counter 1 and adjust the video data. I'll shift 100 upwards.

Also, the above is about the vertical direction, but the exact same thing is true.
The same can be said of FHl and FH4, and by adjusting these, the deviation in the left and right direction can be adjusted.

Moreover, as shown in FIG. 4, the video data 150 is
If the value is larger than 00, flags FV2 and FV5 are enabled. That is, in the case of the state shown in Fig. 4,
Consider the case where you want to align the upper sides. in this case,
First, change the Q1 output of latch 5 from high to low.
Adjust row counter 1. At this time, if the shift is sudden, for example, the shift may go too far downward. Then, the current shift shifts the Q4 output of latch 5 to low. This shift continues until the Q2 output of latch 5 goes high, at which point the shift ends. At this time, if the shift is not stopped under the condition that Ql becomes high, it will shift upward and Ql becomes high, and then the shift will start in the direction of making Ql low again, repeating the above process. The screen vibrates.

Also, if the video data shifts downward for some reason after positioning, if Ql and Q4 of latch 5 are the only criteria for determining the vertical position adjustment, Ql has already become low. , so it is not possible to judge whether it has shifted downward, but the Ql of latch 5
By using this, the CPU 7 can recognize that a shift has occurred due to Ql changing from high to low, and can start the alignment sequencer again.

In preparation for the above situation, flags Fv2 and Fv3 are necessary.

〔effect〕

Conventionally, the image position was adjusted by a person while looking at the screen, but by using this display control device as explained above,
Adjustment of the image position can be performed automatically on the display device side.

In addition, in the case of the present invention, flags FV1 to FV4, FH1 to F
Since the status is the result of ANDing H4 and the video signal, the image position adjustment can match the actual image position in the video data with the actual screen, making it a practical screen. Alignment becomes possible.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention. FIG. 2 is a time chart showing the operation of the embodiment shown in FIG. Third. FIG. 4 is a diagram illustrating the relationship between video data and a real screen. 1... Row counter 2... Column counter 4...-J K-Flip-flop 5...D-Flip-flop 6...-V S C edge detection Circuit 7...C
P U 8... Vertical synchronization signal (VSC) 9...
Horizontal synchronization signal (H8C) 10...Dot clock (DCK) 11...Video signal (VD) Applicant: Seiko Epson Corporation No. 3, No. 4

Claims (1)

[Claims] A means for specifying a non-display section in vertical scanning, a means for specifying a non-display section in horizontal scanning, and a logical product of the outputs from both the means and a video signal to generate information indicating the state of screen misalignment. A display control device comprising means for: