JPH02224589A - Screen display device - Google Patents

Abstract

PURPOSE:To avoid unnatural display change on the screen by providing a character control means to a display control circuit and providing a synchronizing means to a display position detection circuit so as to vary the location of a character synchronously with a horizontal synchronizing signal. CONSTITUTION:When an address representing an address of a display character register 61 and a value to be stored in the register 61 are inputted to an input control circuit 3 in terms of serial signals from an externally mounted control circuit such as a microcomputer, a prescribed value representing the location of the character is stored in the register 61. Thus, a character control means 131 in a display control circuit 13 is operated to change the location of the character displayed on the screen. The change in the location of the display character in this case is occurred synchronously with a horizontal synchronizing signal with a synchronizing means 11a in a display position detection circuit 11. Thus, even when a prescribed value is set to the register 61 on the way of the display of the screen, the location of the display character is changed synchronously with the horizontal synchronizing signal to avoid the unnatural display change in the screen.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a screen display device that displays characters and patterns such as channel numbers in broadcast images displayed on a display device such as a cathode ray tube. .

[Prior Art] FIG. 3 shows an example of the configuration of a conventional screen display device of this kind. In FIG. 3, 1 is a display oscillation circuit to which the oscillation output of the π-type LC oscillation circuit 1a is supplied; 2 3 is a timing generator that generates various timings using signals oscillated by the display oscillation circuit 1, and 3 is a timing generator that generates various timing signals from the output of the timing generator 2 and an external control circuit such as a microcomputer (not shown) for controlling the screen display device. Input terminals 3a to 3c
4 is a data control circuit, 5 is an address control circuit, and 7 is a display data memory for storing control data. , RAM.

A display character memory 8 stores characters and patterns to be displayed in the font structure shown in FIG. 4, and is composed of a ROM. 6 is a display control register that latches commands such as display control among the outputs of the input control circuit 3; 9 is a terminal 9a, 9b;
11 is a synchronization signal switching circuit that selectively outputs either a horizontal or vertical synchronization signal of the image signal supplied to the image signal or a horizontal or vertical synchronization signal generated internally; A display position detection circuit for detecting the display position of patterns, etc.

Reference numeral 13 denotes a display control circuit which controls the display of the output of the display character memory 8 in accordance with display commands from the display control register 6. This screen display device is composed of the above-mentioned circuits, and the output of the display control circuit 13 is supplied to the video mixer 17.
A composite video signal is output via the IDEO terminal 17a. Further, the display control circuit 13 outputs R, G, B color signals, etc. via terminals 13a to 13f. 1
0 is an H counter, 14 is a shift register, 15 is an oscillation circuit for generating a synchronizing signal to which the oscillation output of the oscillation element circuit 15a is supplied, 16 is a timing generator for generating a synchronizing signal, and 21 is a blinking circuit.

Next, the operation will be explained. The input control circuit 3 processes control data input from a microcomputer or the like through terminals 3a to 3c, causes a display control register 6 to latch commands such as display control, and displays character codes and the like as display contents. It is stored in the data memory 7. During display, the character code stored in the display data memory 7 accesses the display character memory 8 as output data, and the display character font output from the display character memory 8 is input to the display control circuit 13. Here, the display data memory 7 is composed of a total of (a + b)·C bits, where one word is (a+b) bits and the number of characters to be displayed is C. On the other hand, in the display character memory 8, one font consists of (JXm) bits, and the type is n.
It is assumed that there are as many characters as there are. The timing for displaying 1 is determined by inputting the synchronizing signal from the image signal to the synchronizing signal switching circuit 9, counting this synchronizing signal with the H counter 10, and using the display position detecting circuit 11 based on this count value to display the characters displayed on the display device. determine the position of The display control circuit 13 synchronizes the display character output with an external video signal, controls the display according to the contents of the display control register 6, outputs it, and supplies it to the video mixer 17.

Note that the synchronizing signal generation oscillation circuit 15 has one oscillation element circuit 1.
5a, it is possible to generate a synchronization signal of the NTSC system or PAL system, and this switching is performed by a signal from the N/P terminal 15b, thereby outputting oscillation of 4 fsc or 2 fsc, and the timing generator 16 for generating the synchronization signal.
Since a synchronizing signal is generated at , it is possible to display on the TV screen even when there is no signal. However, fsc is a color subcarrier, and is 3.58 MHz in the NTSC system and 4.43 MHz in the PAL system.

In addition, the video mixer 17 allows NTSC and P
It is possible to generate an AL type composite video signal and to superimpose it onto an external composite video signal. The composite video signal has character level (LECHA), external composite video input (cv I N), and blanking level (LEB).
K) , background carrier color signal input (R8IN), color burst input (CBIN), and sync chip level are switched and synthesized using analog switches and CVIDEO
It is output from the terminal 17a.

[Problem to be Solved by the Invention] By the way, in conventional screen display devices, when attempting to change the position of displayed characters by setting a predetermined value in the display control register, the value set in the display control register is There was a problem in that the position of the characters changed at some point, and the position changed in the middle of the display screen.

This invention was made to solve the above-mentioned problems, and aims to eliminate unnatural display changes on three screens by changing the position of characters in synchronization with a horizontal synchronizing signal.

[Means for Solving the Problems] A screen display device according to the present invention includes character control means for setting a predetermined value in a register for one display character in a display control circuit to change the position of a character displayed on the screen. , when the position of the displayed character is changed by the display control means, a synchronization means is provided for changing the position of the character in synchronization with a vertical synchronization signal and a subsequent horizontal synchronization signal.

[Operation] When a predetermined value is set in the display character register, the synchronization means generates a signal that changes the position of the character in synchronization with the vertical synchronization signal and one subsequent horizontal synchronization signal according to the set value. Output. When this synchronization means outputs a signal for changing the position of a character, the character control means changes the position of the displayed character at the time this signal is output.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings. Note that the same components as those in the prior art are given the same numbers and their explanations are omitted. FIG. 1 is a block diagram showing an embodiment of the present invention. In the figure, 61 is a display control register 6 that stores a predetermined value for changing the position of displayed characters.
131 is a character control means provided in the display control circuit 13 that changes the position of displayed characters; lla is a vertical synchronization signal and any one of the signals generated after this vertical synchronization signal; This is synchronization means for changing the position of displayed characters in synchronization with the horizontal synchronization signal of.

Next, the operation will be explained. An address indicating the address of the display character register 61 from an external control circuit such as a microcomputer,
When the values to be stored in the display character register 61 are sequentially input to the input control circuit 3 as serial signals, a predetermined value indicating the character position is stored in the 0 display character register 61 in the display character register 61. When the value of is stored, the character control means 131 in the display control circuit 13 is activated to change the position of the character displayed on the screen. At this time, the position of the displayed character is changed in synchronization with the horizontal synchronization signal by the synchronization means 11a.

FIG. 2 is a diagram showing an example of the configuration of this synchronizing means 11a, in which 113 is a flip-flop;
a and 113d are input side terminals of the flip-flop 113;
113b is the output terminal of the flip-flop 113;
3c is a clock input terminal of the flip-flop 113. Here, the input side terminal 113a is set to ``1'' or ``0'' according to a predetermined value set in the display character register 61.
A signal with a level of
One horizontal synchronization signal after the vertical synchronization signal is applied, and a signal for changing the position of the character is output from the output terminal 113b.

In such a configuration, when a predetermined value is set in the display character register 61 and a signal of '1 level is applied to the input side terminal 113a, the rising or falling of the vertical synchronizing signal and the subsequent horizontal synchronizing signal At the point in time, the output terminal 113b switches from '0' to 11' or from '1' to '0 level. Therefore, the position of the displayed character changes at the time of rising or falling of the clock of the vertical synchronizing signal and the subsequent horizontal synchronizing signal, that is, at the time of switching the screen.

[Effects of the Invention] As explained above, according to the present invention, there is provided a character control means for setting a predetermined value in a register for one display character in a display control circuit to change the position of a character displayed on a screen; When changing the position of displayed characters by the above-mentioned display character control means,
Since synchronization means is provided for changing the position of the character in synchronization with the vertical synchronization signal and the subsequent horizontal synchronization signal,
Even if a predetermined value is set in the display character register during the display of the screen, the position of the displayed character changes in synchronization with the horizontal synchronization signal, which has the effect of eliminating unnatural display changes on the screen.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIG. 2 is a detailed block diagram of a specific example of the synchronization means in FIG. 1, and FIG.
This figure is a block diagram of a conventional screen display device, and FIG. 4 is a block diagram of a font structure in a conventional display character memory. DESCRIPTION OF SYMBOLS 1... Display oscillation circuit, 2... Timing generator, 3... Input control circuit, 4... Data control circuit, 5... Address control circuit, 6... Display control register, 7... ... Display data memory, 8... Display character memory, 9... Synchronization signal switching circuit, 11... Display position detection circuit, 13... Display control circuit, 17...
Video mixer, 61...Display character register, 13
1...Character control means, lla...Synchronization means. In the drawings, the same reference numerals indicate the same or corresponding components. Agent: Masuo Oiwa (and 2 others) Procedural amendment (voluntary) February 22, 1990α Contents of amendment (1) “Horizontal synchronization signal” on page 7, line 12 of the specification. Correct as "vertical synchronization signal". 2. Screen display device for more than the name of the invention 3. Person making the amendment Representative Officer R. Kimoriya 4. Agent

Claims (1)

[Scope of Claims] A screen display device that displays characters or patterns on a display device such as a cathode ray tube includes an oscillation circuit that generates signals that serve as reference for various timings, and various timings based on the oscillation signals of the oscillation circuit. A timing generator that generates a signal, an input control circuit that accepts and processes a control signal from an external control circuit such as a microcomputer, a synchronization signal switching circuit that inputs a synchronization signal for a video signal to be displayed on the display device, and A display position detection circuit that counts synchronization signals to detect the display position of the display device, and control data such as characters, pattern codes, blinking information, etc. that are processed by the input control circuit and are to be displayed on the display device. a display data memory for storing; a display character memory for storing fonts of characters displayed as the display contents;
a display control circuit that outputs a predetermined display signal to display display content at a predetermined position of the display device based on a position detection signal from the display position detection circuit; a display signal output from the display control circuit; and a display signal output from the display control circuit and the video signal. and a display control register that holds data input from the external control circuit to the input control circuit, and stores data for setting character positions in the display control register. the display control circuit has a character control means for changing the position of the displayed character;
The display position detection circuit sets a predetermined value in the display character register and synchronizes with the vertical synchronization signal and the subsequent horizontal synchronization signal when the character control means changes the position of the display character on the screen. A screen display device comprising synchronization means for changing the position of the displayed characters.