JPH02224584A - Screen display device - Google Patents

Abstract

PURPOSE:To output a character string with an underline without provision of plural display character memories or the like by providing an underline display register, a character memory and an underline memory or the like. CONSTITUTION:A display character memory 8 is provided with a character memory 81 and an underline memory 82. The memory 81 stores character fonts such as characters and patterns and the memory 82 is provided so that a dot output of an underline font corresponds to each dot output line. Moreover, a display control register 6 is provided with a character display register 6b and an underline display register 6a giving a command to access the memories 81 and 82 simultaneously. Thus, the font output with an underline is attained with one access without requiring plural memories 8 or a memory 8 storing fonts with an underline to quicken the access of the font with the underline.

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] In recent years, TVs and VTRs have rapidly become more diversified, multi-functional, and have improved operability, and there has been a demand for easy-to-see displays of channels, VTR operating states, and the like. Therefore, there is a screen display device that has an underline display function and provides an underline to a character string consisting of letters or characters indicating an operating state to improve visibility.

FIG. 3 shows an example of the configuration of a conventional screen display device of this type. 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 is a timing generator that generates various timings using the signal oscillated by the display oscillation circuit 1, and 3 is a timing generator for this. Input control for inputting the output of the timing generator 2 and control data (commands and character codes for display on/off, etc.) input to each input terminal 38 to 3c from a microcomputer, etc. (not shown) for controlling the screen display device. 4 is a data control circuit, 5 is an address control circuit, and 7 is a display data memory for storing control data, which is composed of a RAM. Reference numeral 8 denotes a display character memory for storing character patterns and the like to be displayed in the font configuration shown in FIG. 4, and is comprised 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 horizontal and vertical synchronizing signal of the image signal supplied to terminals 9a and 9b, or internally generated horizontal and vertical synchronizing signals; 11 is a display position detection circuit for detecting the display position of characters, patterns, etc. on the display device; 13 is a display control circuit; The display of the output of the display character memory 8 is controlled in accordance with the display command of the display control register 6. This screen display device is composed of the above circuits, and the output of the display control circuit 13 is supplied to the video mixer 17, which outputs a composite video signal via the CVIDEO terminal 17a. Further, from the display control circuit 13,
R, G, B color signals, etc. are outputted via terminals 13a to 13f. 10 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 character memory 8 is input to the display control circuit 13. Here, the display data memory 7 is composed of (a+b) bits in total, assuming that one word is (a+b) bits and the number of characters to be displayed is C. On the other hand, it is assumed that one font of the display character memory 8 is composed of (jXm) bits, and there are n characters of types.

The display timing is determined by inputting the synchronization signal from the image signal to the synchronization signal switching circuit 9, counting this synchronization signal with the H counter 10, and using the display position detection 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 is the 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, whereby the 4fsc outputs 2fsc oscillation, and the timing generator 16 for generating the synchronization signal outputs 2fsc oscillation. Since a synchronizing signal is generated at , it is possible to display on the TV screen even when there is no signal.

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 (LEBK).
), background carrier color signal input (R8IN), color burst input (CBIN), and sync chip level are switched and synthesized using an analog switch and output from the CVIDEO terminal 17a.

In the above configuration, the "L pt" of the font 1a shown in FIG. 6 (1dl) and the "E" of the font 1b shown in FIG.
” and “-” (underline) of font 2 shown in FIG. 6(C) are stored in display character memory 8, and display data memory 7 controlled by display control register 6 and timing generator 2 is accessed twice and the font 1 stored in the display character memory 8 is
a and font 2 and font 1b and font 2 each 2
Read times. Then, the fonts 1 and 2 are logically summed by a synthesis means (not shown) and latched, as shown in FIG. 6, 1dl.
The underlined character string can be displayed by configuring and outputting the font 3 of the underlined character string "LP" shown in FIG.

[Problem to be solved by the invention] The conventional screen display device is configured as described above, and T
Since character output must be output from the display control circuit 13 to a TV cathode ray tube or the like in accordance with the scanning of V (hereinafter referred to as scanning), reading from the display character memory 8 is performed by real-time access in accordance with the above-mentioned scanning. High speed is required. However, the above method has a problem in that it is very difficult to perform real-time processing by accessing the display character memory 8 twice or more times in conjunction with scanning.

Therefore, as shown in FIG. 5, the display character memory 8 is composed of a first display character memory 8a and a second display character memory 8b. A synthesis circuit 80 that synthesizes the outputs of the second display character memories 8a and 8b
will be established. the first and second display character memory 8a;
8b is simultaneously accessed by the address control circuit 5, and the "" of font 1a is accessed from the first display character memory 8a.
L'', ``-'' of font 2 is read from the second display character memory 8b, and 'E'' of font 1b is read from the first display character memory 8a, second display character memory 8.
The "-" of font 2 is read from b and synthesized by the synthesis circuit 80 to create an underlined character string ``''U'''
-, however, in order to obtain a composite output, it is necessary to provide a plurality of display character memories 8 and to obtain a composite output.
Providing a font with an underline for each font in the display character memory 8 would be extremely inefficient due to the increase in the number of characters. There was a problem.

This invention has been made to solve the above-mentioned problems, and it is possible to obtain a font output with an underline in one access, and it is provided with a plurality of synthesis circuits 80 and display character memories 8. To provide a screen display device capable of outputting an underlined character string without storing an underlined font in the display character memory 8.

[Means for Solving the Problems] In the screen display device according to the present invention, a display character memory that stores characters, patterns, etc. to display display contents is a character memory that stores fonts of characters such as characters and patterns. , and an underline memory provided so that dot outputs of the underline font correspond to each dot output line of this character memory, and a display control register that accesses data and addresses for the content to be displayed. a character register for accessing the character memory;
It has an underline display register for instructing simultaneous access to the character memory and underline memory.

[Function] The screen display device according to the present invention has an underline memory provided so that dot output of an underline font corresponds to each dot output line of a character memory that stores fonts of characters such as letters and patterns. The underline display register instructs the configured display character memory to be accessed at the same time as the above character memory, outputs underline dots at the same time as dots for each font, and outputs underlined characters in one access. Get columns.

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. Components that are the same as those in FIGS. 3 to 6 are designated by the same reference numerals, and the description thereof will be omitted. In the figure, 18 is a video signal generation circuit that generates each internal video signal, and 19 is a port output control circuit that outputs various signals from port output terminals 19a to 19f. Further, as shown in FIG. 2, the display character memory 8 is provided with a character memory 81 in which fonts of each character and characters are stored, and an underline memory 82 in parallel with this character memory 81. That is, each dot output line 81 . - Underlined dot output 82. on 81n. ~82n is provided, and each output line L I NE
Output every 1 to 12. In addition, display control register 6
has a character display register 6b for displaying characters such as letters and patterns, and an underline display register 6a for displaying an underline. The underline display register 6a is controlled by the underline display signal outputted from the input control circuit 3, and an underline display signal is output to the display data memory 7.

Next, the operation will be explained. It is assumed that an underline display signal from the input control circuit 3 controls the underline display register 6a to display an underline. At the same time as the display control register 6 accesses a character, the underline display register 6a accesses the underline memory 82 of the display character memory 8 via the display data memory 7. For example, Figure 6 (
When accessing "L" of font 1a of font 1a in Figure 6 (C1), access "" of font 2 of underline font 2 of
When accessing font 2, access "-" of font 2. The accessed font 1a's IFL", font 1b's "E" and font 21711 are on the same dot output line 8 in the display character memory 8.
1. ~81n, and outputs the underlined character string "Ldan" shown in FIG.
4 and the display control circuit 13, a character string with an underline ν can be displayed on the display device.

[Effects of the Invention] As described above, according to the present invention, a screen display device includes a character memory that stores a font of a character such as a character or a pattern, and a dot of an underline font on each dot output line of this character memory. A display character memory consisting of an underline memory provided so that outputs correspond to each other, a character register for accessing the character memory, and an underline for instructing simultaneous access to the character memory and the underline memory. By using a display control register having a display register and a display control register, it is possible to output an underlined font in one access without having to provide multiple display character memories or a display character memory that stores underlined fonts. This makes it possible to speed up access to the attached font, and is effective in terms of circuit configuration.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a screen display device according to an embodiment of the present invention, FIG. 2 is a detailed circuit diagram of a single display character memory,
3 and 5 are block diagrams and partial block diagrams of conventional screen display devices, FIG. 4 is a block diagram showing the configuration of display characters, and FIG. 6 (at to fdl are diagrams showing each font. 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, 6a.・・Underline display register, 6b・・
・Character display 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, 18...Video signal generation circuit, 19...Port output control circuit, 8
1...Character memory, 82...Underline memory. Figure 4

Claims (1)

[Claims] In a screen display device that displays characters, patterns, etc. on a display device such as a cathode ray tube, there is provided an oscillation circuit that generates signals that serve as a reference for various timings, and a system that generates various signals based on the oscillation signals of the oscillation circuit. a timing generator that generates a timing signal; an input control circuit that receives and processes a control signal from an external control circuit such as a microcomputer; and a synchronization signal switching circuit that inputs a synchronization signal for a video signal to be displayed on the display device; A display position detection circuit that counts this synchronization signal 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 the above display contents; a display character memory for storing the font of the characters displayed as the display contents;
A video mixer that mixes a predetermined display signal with the video signal in order to display display contents at a predetermined position of the display device using a position detection signal from the display position detection circuit; The display character memory includes a display control register that holds input data, and a character memory that stores the font of characters such as letters and patterns, and an underline font on each dot output line of this character memory. and an underline memory provided so that dot outputs correspond to each other, and the display control register is configured to simultaneously access a character register for accessing the character memory and the character memory and the underline memory. 1. A screen display device comprising: an underline display register for instructing.