JPH1069267A - Screen display circuit - Google Patents

Abstract

(57) [Problem] To provide a screen display circuit capable of coloring in dot units or line units in addition to a conventional color addition function. When the same display as that of the related art is performed, a switching bit A is selected, R, G, and B character data are read in parallel from a character ROM 122, and sequentially shifted by shift registers 141, 142, and 143, and an AND gate 151 is displayed. , 152 and 153, the logical product with the R, G, B signals is obtained and output. When the switching bit B is selected, the character data for each of R, G, and B is individually shifted by the shift registers 141, 142, and 143, and a serial signal is output, and is output as it is as an R, G, and B signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screen display circuit, and more particularly to a screen display circuit for coloring font data of displayed characters.

[0002]

2. Description of the Related Art In a television receiver, characters and patterns indicating channels and various operating states are displayed.

FIG. 5 is a block diagram of a conventional display device, and FIG. 6 is a diagram showing a configuration example of a character font in a conventional example.

In FIG. 5, a synchronization signal is inputted to a synchronization signal input circuit 1, and a horizontal synchronization signal of the synchronization signal is given to an oscillation circuit 2 and an H counter 3. The oscillation circuit 2 generates a large number of pulse signals within one horizontal synchronization and supplies the pulse signals to the timing generator 4. Various timing signals are generated in the timing generator 4 and the display data R
AM9 and the character ROM 12. The H counter 3 counts the horizontal synchronizing signal, and the count output is given to the display position detecting circuit 5.

On the other hand, a control signal for display is input to the input control circuit 6, and the input control signal
The address control circuit 7 specifies the address of the display data RAM 9, and the data control circuit 10 specifies the address of the display data RAM 9.
Is controlled to a read state. The display control register 8 stores character codes such as characters to be displayed and color data for display data RA.
Give to M9. Further, the display control register 8 gives data indicating the display position to the display position detection circuit 5. The display position detection circuit 5 detects an address corresponding to the display position from the count output of the H counter 3 and supplies the address to the read address control circuit 11. Read address control circuit 11 supplies a read address signal of that address to display data RAM 9. The display data RAM 9 supplies an address signal to the character ROM 12. The character ROM 12 reads the bits of the corresponding font in parallel in response to the address signal, and the shift register 14 sequentially shifts the parallel bits and converts the bits into serial character data.
Give 5 The display control circuit 15 adds a designated color to the font and displays a desired character or pattern on the screen.

As shown in FIG. 6, for example, one font is composed of pixels of l.times.m dots. If the character ROM 12 contains n fonts of this font, the character ROM 12 is used. The capacity of l ×
It is equivalent to mxn dots.

[0007]

In the conventional display device shown in FIG. 5, the coloring is performed in units of characters, and it is not possible to perform coloring in units of arbitrary dots or units of one line. For example, if only the dots around the character can be colored with different colors, the character can be displayed more vividly, but such a method cannot be adopted.

Therefore, a main object of the present invention is to provide a screen display circuit which can be colored in dot units or line units in addition to the conventional functions.

[0009]

The invention according to claim 1 is
A screen display circuit for displaying an arbitrary character on a screen display device of a progressive scanning system, wherein character information storage means for storing character information for each of three primary colors and character information storage means for each of three primary colors are output. Shift means for shifting the character information for each color, and first switching means for switching between serially outputting the character information for each color shifted from each shift means or outputting the character information for each color; Display data output means for outputting display data having a character code, color data, and a selection bit; address designating means for designating an address of character information storage means based on the outputted character code; AND means for calculating the logical AND with the character information output serially from the means A second switching means for switching whether to output the output of the logical product means and the character information for each color outputted from the first switching means, and a first switching means in response to a selection bit outputted from the display data output means. And switching control means for switching the second switching means.

In the invention according to claim 2, the character information storage means of claim 1 includes color designation information for coloring for each line, and the logical product means includes a color output from the display data output means. Instead of the data, color designation information from the character information storage means is provided.

[0011]

FIG. 1 is a block diagram showing an embodiment of the present invention. This embodiment is different from the conventional address control circuit 7 and display data RAM shown in FIG.
9, the character ROM 12, the shift register 14, and the display control circuit 15 are replaced by a character ROM address generation circuit 71, a display data RAM 91, and a character RO.
M122, shift registers 141, 142, 143 and A
ND gates 151, 152, and 153 are provided, and a character ROM 121 is further provided. Shift register 14
1 and 142, 142 and 143
00 and 201 are provided. Changeover switches 200, 20
When 1 is switched to the A side, shift registers 141 and 1
42 and 143 output serially converted character data, and the character data is AND
Gates 151, 152, and 153 are provided to one input terminals. The other input terminals of the AND gates 151, 152, 153 are supplied with R, G, B color signals from the display data RAM 91. The outputs of the AND gates 151, 152, and 153 are supplied to the A inputs of the changeover switches 202, 203, and 204. The B input is connected to the B side of the changeover switch 200, the B side of the changeover switch 201, and the output of the shift register 143. You.

The character ROM address generating circuit 71 includes a 1/4 frequency divider 72 and a 1/3 frequency divider 73.
The changeover switch 205 switches the output of the １ ／ frequency divider as it is or the output of the １ ／ frequency divider to the input of the ３ frequency divider. Character ROM1
Data is arranged in the same manner as in the prior art, and character ROM 122 is arranged for each of red (R), green (G), and blue (B) data. Shift register 141
Corresponds to R, the shift register 142 corresponds to G, and the shift register 143 corresponds to B.
The display data RAM 91 has switches 200 to 20.
An A / B switch bit for setting whether to switch 5 to the A side or to the B side is included.

FIG. 2 is a diagram showing a configuration example of a character contact according to an embodiment of the present invention. In this embodiment,
In a single font composed of pixels of 12 × 16 dots, the numbers (l, m) in the matrix indicate that the dots are dots in one row and m columns.

Next, the operation of the screen display circuit shown in FIG. 1 will be described. First, when the same display as in the related art is performed, the A / B switching bit of the display data RAM 91 is set to A selection. A changeover switch 200 to a changeover switch 200 to
205 is switched to the A side. In the same manner as in the conventional example, the horizontal positioning clock signal is frequency-divided by the 1/4 frequency divider 72 and the 1/3 frequency divider 73 of the character ROM address generation circuit 71, and the character code data of the display data RAM 91 is obtained. Is supplied to the character ROM 121, and data for 12 dots is simultaneously read from the character ROM 121 into the shift registers 141, 142 and 143 in parallel. Since the changeover switches 200 and 201 are each switched to the A side, they are given as 12-bit serial data to one input terminal of the NAND gates 151, 152 and 153 in order from the dot (1, 1) of the character ROM 121. AND gates 151, 152 and 1
The other input terminal of the display data RAM 91 receives R,
Since the G and B color signals are given, the logical product of the serial character data and the color signal is obtained, and R, G, and
B data is output. Therefore, in this case, coloring is performed in character units.

Next, a case where the A / B switching bit of the display data RAM 91 is selected as B will be described. In this case, the changeover switches 200 to 205 are switched to the B side. Reading from the display data RAM 91 is the same as that of the conventional example. However, since the changeover switch 205 of the character ROM address generating circuit 71 is switched to the B side, the horizontal positioning clock signal is reduced to 1/4 frequency divider. The frequency is divided by 72 and the character R
The 4-bit data for each of R, G, and B that are output to the OM 122 and stored separately from the character ROM 122 are read out in parallel, and
1, 142, 143. Selector switch 20
Since 0 and 201 are switched to the B side, character data is read from each of the shift registers 141, 142 and 143 for each of R, G and B. Selector switch 20
2, 203 and 204 are also switched to the B side, so that the R, G, and B dots output from the shift registers 141, 142, and 143 are directly output as R, G, and B dots. Colored. However, since the data shift is completed in four bits, it is necessary to transfer the data to the shift register every four bits.

FIG. 3 is a block diagram showing another embodiment of the present invention, and FIG. 4 is a diagram showing a configuration example of a character font in another embodiment of the present invention.

In FIG. 3, a color designation RAM 12A is added to the conventional character ROM 12 shown in FIG.
As shown in FIG. 4, one character is composed of m × 1 dots of horizontal m bits and vertical 1 bits. One horizontal line (m dots) of font data is composed of a character ROM 12 of m bits, and a total of 3 bits of color is specified for each line of data for red (R), green (G), and blue (B). . In the color designation ROM 12A, the display control circuit 15 stores the data of each bit of R, G, and B by the shift register 14 which holds the data of one line of the font data.
By taking the logical product with the output, it is possible to color each font output line of one font.

[0018]

As described above, according to the present invention, the coloring circuit for each dot is added to the conventional coloring circuit for each character, so that the color of character data is specified in units of dots or one line. Screen display by various color designations can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a screen display circuit according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a configuration example of a character according to an embodiment of the present invention.

FIG. 3 is a block diagram showing a screen display circuit according to another embodiment of the present invention.

FIG. 4 is a diagram showing a configuration example of a character font according to another embodiment of the present invention.

FIG. 5 is a block diagram showing a screen display circuit according to a conventional example.

FIG. 6 is a diagram illustrating a configuration example of a character font in a conventional example.

[Explanation of symbols]

12 character ROM, 12A color designation ROM, 14
Shift register, 15 display control circuit, 71 character ROM address generation circuit, 72 1/4 frequency divider,
73 1/3 frequency division, 91 display data RAM, 12
1,122 Character ROM, 141, 142, 14
3 shift register, 151, 152, 153 AND
Gate, 200-205 changeover switch.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masaaki Kimura 3-1-1-17 Chuo, Itami-shi, Hyogo Mitsubishi Electric Semiconductor Software Corporation (72) Inventor Izumi Takaishi 3-1-1 Chuo, Itami-shi, Hyogo No. 17 Mitsubishi Electric Semiconductor Software Corporation

Claims (2)

[Claims] 1. A screen display circuit for displaying an arbitrary character on a screen display device of a progressive scanning system, comprising: character information storage means for storing character information for each of three primary colors; Shifting means for shifting the character information output from each of the colors for each color; and a switching means for switching whether to serially output the character information for each color shifted from each of the shifting means or to output each character. 1 display means, display data output means for outputting display data having a character code, color data, and selection bits, and an address of the character information storage means based on the character code output from the display data output means. Addressing means for specifying the color data output from the display data output means. AND means for calculating the logical AND of the data and the character information serially output from the shift means; and a switch for switching whether to output the output of the logical AND means and the character information for each color output from the switching means. 2. A screen display circuit, comprising: a second switching means; and a switching control means for switching between the first and second switching means according to a selection bit output from the display data output means. 2. The character information storage means includes color designation information for coloring one line at a time. The logical product means stores the character data instead of the color data output from the display data output means. 2. The screen display circuit according to claim 1, wherein the color designation information is provided from the information storage means.