JPH04337795A - Screen display controller - Google Patents

Abstract

PURPOSE:To reduce the cost of the controller which displays character information and image information on a screen in plural colors by decreasing the capacity of a font memory stored with pieces of font information on respective information. CONSTITUTION:The font memory 2 is stored with only character fonts having no color information without being stored with character fonts with color information by deciding the character information and image information by a code deciding means 5, and a coloring process for the character information is performed differently by a coloring process means 7.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a screen display control device applied to a liquid crystal display device used in a copying machine, a personal computer, etc. This invention relates to improvements to a display screen control device for displaying images.

0002

2. Description of the Related Art Recently, liquid crystal display devices used in personal computers, copying machines, etc. have already been provided that display character information and image information in a plurality of colors to make various types of information easier to visually see.

Conventionally, a screen display control device applied to this type of liquid crystal display device has a video RAM (VIDEO RAM) with a memory capacity corresponding to the display screen, as shown in FIG.
RAM) 100, and predetermined character codes and graphic codes are stored in this video RAM 100. For example, when displaying various information in four colors, black, dark gray, light gray, and white, a light gray A font ROM (FONTROM) 101 and a font ROM 102 for dark gray are prepared, and each font ROM
Font information for light gray and dark gray (when the font bit information is 1 indicates light gray or dark gray) is stored in advance in 101 and 102, and the font information for light gray and dark gray corresponding to the character code and graphic code is stored in advance. A dark gray mixing circuit 1 inputs font information from a light gray font ROM 101 to a light gray mixing circuit 103 that adjusts to a light gray display font using a gray signal, and adjusts to a dark gray display font using a dark gray signal.
Font information from the dark gray font ROM 102 is input to 04, and the font output from each mixing circuit 103, 104 is sent to a liquid crystal display timing controller (LCD controller) via an OR gate circuit 105.

[0004] In this type, character information is also processed in the same way as image information, and among the font information in each font ROM 101, 102 corresponding to a predetermined code,
Font ROM10 with corresponding bits for light gray
The part where only 1 is 1 is light gray, the part where only font ROM 102 for dark gray is 1 is dark gray, the part where both font ROMs 101 and 102 are 1 is white, and the part where both font ROMs 101 and 102 are 0 is black. This makes it possible to display .

[0005]

[Problems to be Solved by the Invention] By the way, in such a conventional screen display control device, the number of display dots is 480×272 [dots] (for example, as a practical use condition).
If one tile is 8 x 16 dots, it is 60 x 17 tiles.
es), number of gradations is 4, required number of screens is graphic: 6
．． For 5 screens (60 x 17 x 6.5 tiles), TEXT (
Text): 1536 characters, graphic coloring:
For each dot, TEXT (character): 8 character/background combinations
Assuming that the capacity of video RAM 100 is 60 x 17 (tiles) x 2 (bytes)
÷1024=2 (Kbites), font ROM10
The capacity of the 1,102 character font area is {15
36 characters x 8 x 16 (dots) x 8 types}÷8 (bi
ts) ÷ 1024 x 2 = 384 (Kbytes), and the capacity of the graphic font area of the font ROMs 101 and 102 is {480 x 272 (dots) x 6.
5 screens}÷8 (bits)÷1024×2=207.2
(Kbytes) and font ROM101,10
The total capacity of 2 is 384 + 207.2 = 591.2 (
Kbytes) is required, and the font ROM
The capacity of the devices 101 and 102 is extremely large, which limits the ability to reduce the cost of the device.

[0006] As the number of color reproduction combinations of character information increases, the capacity of the character font area increases, and the above-mentioned technical problem becomes more pronounced.

[0007] The present invention has been made to solve the above-mentioned technical problems, and in a type in which text information and image information are displayed on a screen in a plurality of colors, when displaying text information in color, By focusing on the fact that it is not possible for the text to partially change color, and only the text, background, and hue need to be considered, the capacity of the font memory in which font information for each information is stored can be reduced. Therefore, the present invention provides a screen display control device that can reduce the device cost accordingly.

[0008]

[Means for solving the problem] That is, this invention
As shown in FIG. 1, there is provided a display screen control device for displaying character information C and image information G having a plurality of colors on a screen D, including an image memory 1 having a memory area corresponding to the display screen D; A character code CC to which a color information bit k indicating the color tone of the character part and a background part and a character information discrimination bit m indicating that the character information C corresponds to the character information C to be displayed, and a character code CC to be displayed. Graphic code GC containing color information corresponding to image information G is stored in image memory 1.
The code setting means 2 is divided into a character code area and a graphic code area, and a character font CF corresponding to the character code CC is stored in the character code area, and a graphic code GC is stored in the graphic code area. Font memory 3 (not necessarily ROM) in which the graphic font GF corresponding to
), a font search means 4 which reads out fonts CF and GF from the font memory 3 in accordance with the codes CC and GC read out from the image memory 1, and a font search means 4 which reads out the fonts CF and GF from the font memory 3 in accordance with the codes CC and GC read out from the image memory 1; code discriminating means 5 for discriminating whether the code is GC;
Based on the information from the code discrimination means 5, the font selection means 6 sorts the output from the font memory 3 into character fonts CF and graphic fonts GF, and the code read from the image memory 1 is discriminated as character code CC. Coloring processing means 7 for coloring the character font CG corresponding to the character code CC output from the font memory 3 based on the color information bit k attached to the character code CC only when the character code CC is That is.

In such technical means, the color information bit k and the character information discrimination bit m are added by using bits that are used as a graphic code GC but are not used as a character code CC. Just do it. In this case, the color information bit k may be selected as appropriate depending on the combination of hues of the character part and the background part, and the character information discrimination bit m may be selected between the character code CC or the graphic code G.
Any type of material may be used as long as it can determine whether it is C or not. Furthermore, the font memory configuration may be appropriately selected depending on the color information to be displayed, such as its capacity and number.

0010

[Operation] According to the technical means described above, the code setting means 2 sets the predetermined character code CC (color information bit k and character information discrimination bit m are added), graphic code GC
is read out after being written into the image memory 1, the font search means 4 reads out the corresponding font from the font memory 3 according to the code, while the code discrimination means 5
determines whether the code read from the image memory 1 is a character code CC or a graphic code GC depending on the presence or absence of the character information determination bit m.

At this time, if the code from the image memory 1 is a graphic code GC, the font selection means 6 selects a graphic font GF that includes color information in advance.
is output as is to the controller on the display device side, but if the code from the image memory 1 is the character code CC, the font selection means 6 colors the character font CF based on the information from the code discrimination means 5. The coloring processing means 7 colors the character font CG based on the color information bit k attached to the character code CC, and then outputs it to the controller on the display device side.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on embodiments shown in the accompanying drawings. FIG. 2 is a block diagram showing an embodiment in which the present invention is applied to a screen display control device for a liquid crystal display device of a copying machine. In this embodiment, display can be performed in four colors: white, light gray, dark gray, and black. It is something to do. In the same figure, reference numeral 20 is a liquid crystal display device (hereinafter referred to as LC).
(abbreviated as D), 21 outputs the imported font to the oscillator 2.
2 is a liquid crystal display timing controller (hereinafter abbreviated as LCD controller) that supplies the LCD 20 in synchronization with the reference clock from 2, and this LCD controller 21
is the central control system of the user interface (CPU23, R
(OM24, RAM25) via a system bus 26. Reference numeral 27 is a control panel on which various operation switches of the copying machine are arranged, and 28 is a memory card interface, each of which is connected to the system bus 26.

Further, reference numeral 30 stores a character code corresponding to character information, information bits accompanying this (color bits and character/graphic discrimination bits to be described later), a graphic code corresponding to image information, and a bitmap font. Video RAM (VIDEO RAM), 3
1 is a bitmap converter that converts a certain area into a bitmap area according to an address signal from the LCD controller 21; 32 is a video RAM that converts data from the CPU 23;
30 is a transceiver for writing data; 33 is a multiplexer for selecting one of the address signal from the CPU 23, the address signal from the bitmap converter 31, and the address signal from the LCD controller 21; 34 is a character font ( Font ROM (FONT
ROM), 35 is a gray scale counter that generates a light gray signal and a dark gray signal according to the timing signal from the LCD controller 21, and 36 is a character that colors the character font only when the font from the font ROM 34 is a character font. coloring circuit,
37 is a bitmap coloring circuit that colors the bitmap font read from the video RAM 30 in a predetermined color (black or white in this embodiment).

In this embodiment, the memory addresses of the LCD controller 21 for the screen display of the LCD 20 are shown in FIGS. 3 and 4. Figure 3 shows a text (TEXT)/graphic (GRAPHIC) screen, 8×16 (
dots) is 1 (tile), 60×17
(tiles) is displayed, as shown in Figure 4.
indicates a bitmap screen, 8 (dots) x 1 (d
ot) unit [equivalent to 1/16 (tile)], 60
x272 areas are displayed, and any area within this area (indicated by A in the figure) can be designated as a bitmap area. In addition, due to processing reasons, 64
It has memory addresses for ×17 (tiles), and a part of the address is a non-display area.

[0015] Furthermore, in this embodiment, the above-mentioned Viteo R
The specific configuration of AM30 is VRA for text (TEXT).
M (abbreviation for VIDEO RAM) - TEXT (2),
VRAM-GRA (2) and VRA for graphics
Equipped with M-BIT. Here, the above characters (TEX
T) VRAM-TEXT and VR for graphics
Two AM-GRAs are provided for each AM-GRA, and these are mutually switched and selected by the start address of the LCD controller 21 so that processing work for rewriting can be performed in the background. .

The above VRAM-TEXT is as shown in FIG.
, As shown in Figure 6, the 2-byte data has a code for 1 tile (8 x 16 dots) of the memory address on the screen, and the lower 11 bits (000h to 5FFh) are
This indicates the address of FONTROMTEXT-A/B, which will be described later. Also, the upper 3 bits (D15, D14, D13)
As shown in FIGS. 6 and 7, a color bit indicating the hue between the character and the background is attached, and 1/0 of the most significant bit D15 of this color bit is D13, D14.
This is a reverse bit that indicates whether or not to invert the coloring of characters and background when the bit data of is the same. Furthermore, in this embodiment, the middle 4 bits of 2-byte data (D9, D1
0, D11, D12: T/G discrimination bits) to determine whether it is a character (TEXT) or a graphic (GRAPHIC).
), and if the 4 bits are [0000] to [0101], it is a character, [01
10] to [1111] represents a graphic.

Further, as shown in FIGS. 5 and 6, the VRAM-GRA has a code for one tile (8×16 dots) of the memory address on the screen in 2-byte data, and the lower 13 bits have a code for (600h). to 1FFFh), FONT ROMGRAPHIC-A/B, which will be described later.
Indicates the address of And FONT ROM G
Color information is added by the combination of bits of RAPHIC-A/B.

Furthermore, the VRAM-BIT has bit data as it is as a font configuration, and is output when a bitmap font is specified.

Further, in this embodiment, the font ROM 34 has two font ROMs as shown in FIG.
It consists of M-A and B, and is divided into a character (TEXT) area and a graphic (GRAPHIC) area, respectively. More specifically, as shown in FIG.
- Characters (TE) at address A [000h to 5FFh]
The character font corresponding to the normal character code is stored in the XT) area, and the character (TEXT) area at address [000h to 5FFh] of font ROM-B stores the inverted character code (bits of the normal character code). The character font corresponding to the reversed version) is stored, and the address [060
h to 1FFFh) graphic (GRAPHIC)
The area contains graphic font A for light gray corresponding to the graphic code (font whose bit [1] is light gray), graphic font B for dark gray corresponding to the graphic code (font whose bit [1] is light gray),
] is stored in a dark gray font).

Then, the font from the font ROM-A is adjusted to a light gray display font using the light gray signal from the gray scale counter 35 (for example, 3 out of 4 reference pulses are at high level). The font from the font ROM-B is input to the circuit 341 and the font from the font ROM-B is input to the dark gray signal from the gray scale counter 35 (e.g. reference pulse 4).
Mixing circuit 3 for dark gray that adjusts the font for displaying dark gray when two of the pulses are high level)
42, and the font output from each mixing circuit 341, 342 is sent to the LCD via an OR gate circuit 343.
The data is sent to the controller.

The basic configuration of the character coloring circuit 36 is as shown in FIG. A character/graphic (TEXT/GRAPHIC) discrimination circuit 361 that discriminates whether a code is a character or a graphic, and a color bit (see FIG. 6) when the character/graphic discrimination circuit 361 determines that the code is a character.
When the character (TEXT) gradation processing circuit 362 performs gradation processing according to the text and the character/graphic discrimination circuit 361 determines that the code is a character, the OR gate circuit 34
If the code is a graphic code, the output from the OR gate circuit 343 is added to the output from the character gradation processing circuit 362 without performing gradation processing by the character gradation processing circuit 362. Text/Graphic that passes through the output as is.
C) selection circuit 363.

In this embodiment, when the character/graphic discrimination circuit 361 determines that the character is a character, the character gradation processing circuit 362 further recognizes the gradation of the character and the background using the upper 3 bits, and performs processing accordingly. It processes light gray signals and dark gray signals to add gradation.

A specific example of the character coloring circuit 36 is shown in FIG. In the figure, symbols DG and LG are a dark gray signal generation section and a light gray signal generation section that are turned ON (1) and OFF (0) for each frame of the screen to generate a dark gray signal and a light gray signal, respectively. Also,
The character/graphic discrimination circuit 361 is VROD4 to VR
The data from OD1 (corresponding to D12 to D9 in Figure 7) is [
0000] to [0101], characters and [0110
] to [1111], it is determined to be a graphic. Furthermore, the character gradation processing circuit 362, when determined as a character by the character/graphic discrimination circuit 361,
Color bits VROD6 to VROD5 (D14 in Figure 7)
~ D13)) according to the predetermined gray scale (Fig.
a gray scale addition circuit section 362 that creates
It is configured with a reverse circuit section 362b that inverts the output from the gray scale addition circuit section 362a when the color bit VROD7 (corresponding to D15 [reverse bit] in FIG. 7) is at a high level. A coloring signal (LC: white, light gray, dark gray, black) and a coloring signal for the background portion (DNC: white, light gray, dark gray, black) are output. In the figure, MUX is a multiplexer that switches and selects inputs A and B in response to a select signal S, and BMP is a signal indicating whether or not the area is a bitmap display area.

Next, the operation of the screen display control device according to this embodiment will be explained. If the code read from the video memory 30 is a graphic code, the graphic fonts from the font ROMs A and B are sent to the LCD controller via the respective mixing circuits 341 and 342 and the OR gate circuit 343. .

At this time, gradations as shown in FIG. 10 are displayed according to the combination of bit data of the font ROM-A and ROM-B. That is, font ROM-A,
If B is (1, 1), it is white (the output from the OR gate circuit 343 is (1, 1)), and the bit data is always mixed with a high-level white signal [OR of light gray signal and dark gray signal]. (1,0) is light gray, (0,1) is dark gray, and (0,0) is black.

On the other hand, if the code read from the video memory 30 is a character code, the font ROM-
The character fonts from A and B are sent to the respective mixing circuits 34.
1,342 and the OR gate circuit 343 to the character/graphic selection circuit 363, but at this time,
After the character coloring circuit 36 performs coloring processing on the character font according to the color bits, the colored character font is sent to the LCD controller.

When examining the memory capacity used in such a screen display control device, for example, as an actual usage condition, the number of display dots is 480 × 272 [dots] (if one tile is 8 × 16 dots, then 60 × 17 tiles) ), number of gradations is 4, required number of screens is graphic: 6.5 screens (
60 x 17 x 6.5 tiles), TEXT: 1
536 characters, coloring is graphic: dot by dot,
TEXT: Assuming that there are 8 types of text/background combinations, the capacity of the video RAM 30 is 60
×17(tiles)×2(bytes)÷1024=
2 (Kbites), the capacity of the character font area of font ROM-A and B is {1536 characters x 8 x 16
(dots)}÷8 (bits)÷1024×2=48
(Kbytes), the capacity of the graphic font area of font ROM-A and B is {480×272(
dots) x 6.5 screen}÷8(bits)÷1024
×2=207.2 (Kbytes), and font R
The total capacity of OM-A and B is 48+207.2=25
5.2 (Kbytes), which shows that the memory capacity of the font ROM is significantly reduced compared to the conventional type (591.2 [Kbytes] under the same conditions of use).

[0028]

Effects of the Invention As described above, according to the present invention, character information and image information are distinguished, character fonts with color information are not stored in the font memory, and character fonts with color information are not stored in the font memory. Since only text fonts are stored in the font memory, and the coloring process for the text information is performed separately, the capacity of the font memory in which the font information for text information and image information is stored can be reduced, and the device cost can be reduced accordingly. The cost can be reduced.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the configuration of a screen display control device according to the present invention.

FIG. 2 is an explanatory diagram showing an embodiment in which the present invention is applied to a screen display control device of a liquid crystal display device of a copying machine.

FIG. 3 is an explanatory diagram showing memory addresses for a character/graphic screen.

FIG. 4 is an explanatory diagram showing memory addresses for a bitmap.

FIG. 5 is an explanatory diagram showing a configuration example of a video RAM.

FIG. 6 is an explanatory diagram showing an example of a data structure stored in a video RAM.

FIG. 7 is an explanatory diagram showing the coloring state of characters.

FIG. 8 is an explanatory diagram showing details of a font ROM and a character coloring circuit.

FIG. 9 is an explanatory diagram showing a configuration example of a font ROM.

FIG. 10 is an explanatory diagram showing the principle of gradation expression for graphic fonts.

FIG. 11 is a circuit diagram showing a specific example of a character coloring circuit.

FIG. 12 is an explanatory diagram showing an example of a conventional screen display control device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1... Image memory, 2... Code setting means, 3... Font memory, 4 Font search means, 5... Code discrimination means, 6...
Font selection means, 7...Coloring processing means, CC...Character code, color information bits k, m...Character information discrimination bits, GC
...Graphic code, CF...Character font, GF...Graphic font

Claims (1)

[Claims] Claim 1: A display screen control device that displays text information (C) and image information (G) having a plurality of colors on a screen (D), the device having a memory area corresponding to the display screen (D). An image memory (1), a color information bit (k) indicating the hue of the text part and background part corresponding to the text information to be displayed (C), and a text information discrimination bit indicating that it is text information (C). Character code (CC) with (m)
) and a graphic code (GC) containing color information corresponding to the image information (G) to be displayed in the image memory (1).
A code setting means (2) for writing in a readable manner, a character code area and a graphic code area are divided,
The character code area stores a character font (CF) corresponding to a character code (CC), and the graphic code area stores a font memory (3) in which a graphic font (GF) corresponding to a graphic code (GC) is stored. ), and a font search means (4) that reads out a font (CF, GF) from the font memory (3) in accordance with the code (CC, GC) read out from the image memory (1).
, code discrimination means (5) for discriminating whether the code read from the image memory (1) is a character code (CC) or a graphic code (GC); and this code discrimination means (5).
Based on the information from the font memory (3), the output from the font memory (3) is divided into a character font (CF) and a graphic font (G
F) font selection means (6) for selecting fonts, and color information bits attached to the character code (CC) only when the code read from the image memory (1) is determined to be a character code (CC). Coloring processing means (7) for coloring the character font (CG) corresponding to the character code output from the font memory (3) based on (k)
A screen display control device comprising: