JP2943495B2 - LSI for on-screen display - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an LSI for an on-screen display, and more particularly to an LSI for an on-screen display for switching a character signal output to a mixing circuit.

[0002]

2. Description of the Related Art Conventional on-screen display LSIs include various display control units, ROM and RAM.
And so on.

FIG. 6 is a block circuit diagram showing an example of a conventional LSI for an on-screen display. FIG.
As shown in FIG. 1, the conventional LSI 33a determines the character size, display position, write address and the like designated by the display information control unit 2 by the data selector circuit 3 based on information from the control block 1 connected to the control microcomputer 11. And sends it to the video RAM 4. The display information control unit 2 inputs a clock and a synchronization signal from the oscillation block 9 and the synchronization signal input unit 10. The transmission block 9 and the synchronization signal input unit 10 are connected to an external LC oscillation circuit 12, a synchronization separation circuit, respectively. 13 is connected.

On the other hand, in the video RAM 4, the control block 1
The display pattern for one screen, the color and blinking information for each character are set by the information from, and sent to the output control block 6 via the character ROM 5 together with the setting information of the display information control unit 2. The output control block 6 receives information from the background control unit 7 and the display ON / OFF control unit 8 set by the information from the control block 1, and outputs and displays the information based on these information. Is performed. Further, the output control block 6 is connected to an external mixing circuit 14. Therefore, the conventional on-screen display LSI 33a can perform display ON / OFF control, color control, and blinking control only in character units.

[0005]

SUMMARY OF THE INVENTION The above-described conventional on-
The screen display LSI has a drawback that, when outputting and displaying a character, only control can be performed in units of characters, and control in units of dots of characters cannot be performed.

An object of the present invention is to provide an LSI for an on-screen display which enables control of such characters in dot units and realizes diversification of display.

[0007]

The present invention provides a character size,
A display information control unit for specifying a display position and a write address; a video RAM for setting a display pattern for one screen, a color per character, and blinking information;
A character ROM for outputting a character specified by AM, a control block for controlling the display information control unit and the video RAM by external control,
Output control for controlling the output of the character ROM by background control and display on / off control based on the control block
On-screen display for LSI that includes a part
, A first counter that counts a horizontal synchronization signal, a second counter that counts dots of a dot oscillation that is a reference of horizontal dots that form the character, and a counter that counts the first and second counter values. By providing two comparators each for comparing and determining, a display selection block for setting a display start position of a dot forming the character, and an output control block including a switch for switching output of the character, By controlling the output control block based on the output of the display selection block, the character is controlled in dot units.

[0008]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block circuit diagram of an on-screen display LSI showing an embodiment of the present invention. As shown in FIG. 1, the LSI 33 of this embodiment is different from the conventional example of FIG. 6 in that the display selection block 15 is added and the output control block 6 is changed accordingly. That is, the present embodiment under the control of the control block 1 connected to the control microcomputer 11, the character size and Viewing position and write addresses and the like designated by the display information control unit 2 via the data selector circuit 3 Send it to the video RAM 4. In the video RAM 4, a display pattern for one screen, a color and blinking information for each character are set, and sent to the output control block 6 via the character ROM 5. The output control block 6
, Information from the background control unit 7 and the display on / off control unit 8 is also transferred, and the output display is performed based on the information.

On the other hand, the display selection block 15 selects a display method under the control of the control block 1 and sets a display start position. Upon receiving this information, the output control block 6 enables partial display of one character.

FIG. 2 is a block diagram of the display selection block shown in FIG. As shown in FIG. 2, the display selection block 15 includes selectors 16 and 17, counters 18 and 19, comparators 20 and 21, a row address counter 22, and a digit address counter 23. 16th and 2nd
The display method is selected by the selector 17 of, and the display start position for “row” or “digit” is set in the comparator 20 or the comparator 21. The output control block 6 is controlled by comparing this value with the values of the counters 18 and 19.

FIG. 3 is a block diagram of the output control block shown in FIG. As shown in FIG. 3, the output control block 6 includes a blinking control unit 24, a character information control unit 25, a background control unit 26, a border control unit 27, and an R signal output control unit 2.
8, a G signal output control unit 29, a B signal output control unit 30, a BLK signal output control unit 31, and a switch unit 32. This output control block 6 turns on the switch unit 32
/ OFF to enable partial display in the vertical direction or partial display in the horizontal direction in one character. For example, in the case of partial display in the vertical direction, since the character size is specified in units of lines, the setting range of the display start position of each line differs depending on the size. In the case of partial display in the horizontal direction, the character size cannot be set in units of digits,
It is necessary to unify the size of each line constituting one screen.

FIG. 4 is a pattern diagram showing an example of the display in FIG. As shown in FIG. 4, in this display example, when displaying a portion in the vertical direction in one character, the display start position of the first line is set from the fourth horizontal scanning line of that line, and the second line is displayed. This is a case where the display start position is set from the eighth horizontal scanning line of the row.

First, based on information from the control block 1,
The first selector 16 and the second selector 17 select the counter 16, the comparator 20, and the row address counter 22. At the same time, based on the information from the control block 1, the display start position in dot units (from which horizontal scanning line of the row the display is started) is set in the comparator 20. In this case, the set value is set in field units, and the range of the set value is n (horizontal) × m (vertical) when the configuration of one character is 0 to m (field) at the minimum size and at the double size. Is 0 to 2 m (field), and similarly is 0 to pm (field) (p = 1, 2,...) When the size is p times. In the case of the minimum size, when 0 is specified, the line is not displayed, and when 1 to m is specified, the display is started from the horizontal scanning line. That is, when the value set in the comparator 20 matches the value of the counter 18 (except 0), a signal for display ON (or OFF) is output through the second selector 17. Therefore, the output control block 6 controls the internal switch unit 32 to start (or stop) the output of the character signal.

FIG. 5 is a pattern diagram showing another example of the display in FIG. As shown in FIG. 5, in this display example, in the horizontal direction, the display start position of the first digit is from the fourth dot of that digit, and the display start position of the second digit is from the eighth dot of that digit. Is the case. First, based on information from the control block 1, the first selector 16 and the second selector 17 select the counter 19, the comparator 21, and the digit address counter 23. At the same time, control block 1
Based on the information from, the display start position of the dot in the horizontal direction is set in the comparator 21 (from which digit of that digit the display starts). When performing this setting, the character size of each line constituting the display screen is the same. The range of the set value is n (horizontal) × m (vertical)
If it is, the minimum size is 0 to n, and the double size is 0 to
2n, 0-pn (p = 1, 2, 2,
…). In the case of the minimum size, if 0 is designated, the digit is not displayed, and if 1 to n is designated, the display is started from the dot. That is, when the value set in the comparator 21 matches the value of the counter 19 (excluding 0),
A signal for display ON (or OFF) is output through the second selector 17, and the switch unit 32 in the output control block 6 is controlled to start (or stop) the output of the character signal.

[0015]

As described above, according to the present invention, by providing a display selection block having a counter and a comparator, a character can be displayed in dot units and partially in the vertical direction or in the horizontal direction. It is possible to realize various displays that could not be displayed so far, and to display O in dot units.
There is an effect that N / OFF control can also be realized. As an example, it is possible to sequentially display from the top or bottom of the screen, or to sequentially display from the left or right of the screen.

[Brief description of the drawings]

FIG. 1 is a block circuit diagram of an on-screen display LSI showing an embodiment of the present invention.

FIG. 2 is a configuration diagram of a display selection block shown in FIG. 1;

FIG. 3 is a configuration diagram of a display control block shown in FIG. 1;

FIG. 4 is a pattern diagram showing an example of a display in FIG.

FIG. 5 is a pattern diagram showing another example of the display in FIG.

FIG. 6 is a block diagram showing an example of a conventional LSI for on-screen display.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 control block 2 display information control unit 3 selector circuit 4 video RAM 5 character ROM 6 output control block 7 background control unit 8 display on / off control unit 15 display selection block 16, 17 selector 18, 19 counter 20, 21 comparator 22 Row address counter 23 digit address counter 24 blinking control unit 25 character information control unit 26 background control unit 27 border control unit 28 R signal output control unit 29 G signal output control unit 30 B signal output control unit 31 BLK signal output control unit 32 Switch 33 LSI for on-screen display

Claims (1)

(57) [Claims] A display information control unit for specifying a character size, a display position, and a write address; a video RAM for setting a display pattern for one screen, a color in character units, and blinking information; A character ROM for outputting the selected character, a control block for controlling the display information control unit and the video RAM by external control, and a background control and a display on / off control based on the control block for the character RO.
In an on-screen display LSI having an output control unit for controlling the output of M, a first counter for counting a horizontal synchronizing signal, and a dot oscillation for a reference of horizontal dots constituting the character are provided. A display selection block for setting a display start position of a dot forming the character by including a second counter for counting dots and two comparators for comparing and determining the first and second counter values, respectively. And an output control block including a switch for switching the output of the character, wherein the output control block is controlled by the output of the display selection block to control the character in units of dots. On
LSI for screen display.