JP2001117548A - Device and method for displaying video provided with character display function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make compressible a font table and also largely reducible the memory capacity for the font table when displaying an arbitrary character in a prescribed character display area. SOLUTION: This video display device is provided with a ROM 11 in which a font table T1 compressed in row unit and a command table T2 for restoring the compressed font table T1 are stored, and a CPU 13 for restoring the original font table T1 in row unit based on the command table T2 stored in the ROM 11. This configuration makes it possible to compress the font table T1 so as to delete data blank parts not displaying the characters, and data string in the blank parts.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video display device having a character display function suitable for a television, a monitor, a liquid crystal display or the like having a function of displaying characters such as characters, symbols, and diagrams. And a video display method. More specifically, when an arbitrary character is displayed in a character display area of m lines × n characters / line, a font table that has been data compressed in units of lines is restored to an original font table in units of lines based on a command table. A restoration means is provided so that the font table can be compressed so as to delete the data of the blank portion in which the character is not displayed and the data string in line units, and the memory capacity for the font table can be greatly reduced. It was done.

[0002]

2. Description of the Related Art In recent years, televisions, monitors, and liquid crystal displays having a function of displaying characters such as characters, symbols, and diagrams have been used. A video display device with this type of character display function (On Screen Displ.
ay: hereinafter also referred to as OSD), displays time on a CRT screen, sets a good night timer,
When a program reservation is set or color adjustment is set in combination with a character, a character is displayed in a predetermined character display area.

FIG. 9 is an image diagram showing an example of character display on a CRT screen according to a conventional system. A video display device with a character display function shown in FIG.
(Referred to as RT) 40 is provided, for example, in the character display area P1 of 5 lines × 15 characters / line on the CRT screen, “OSD
"VPOSION" character, "-" horizontal line, "← 1"
A character such as a sign or a numerical value “00 →” is displayed with a space (blank portion) above and below the character display area.

In order to display these characters, the video display device is provided with a microcomputer (hereinafter also referred to as a microcomputer), and a ROM is provided inside the microcomputer.
(Read only memory). FIG. 10 is an image diagram showing a font table (an example of data storage) of a ROM according to the conventional method.

In the ROM 1 shown in FIG. 10, for example, in order to display a character in the character display area P1 shown in FIG.
Five are stored consecutively, and “OSD VPOS” in the second row is stored.
As the character display data “ION”, “ff 203
b 2d ff 3e 38 20 3b 323 c
32 20 37 ff ”is stored, and“ ff ff ff ”is displayed as horizontal line display data“ − ”in the third row.
15 16 16 16 16 16 16 161d
ff ff ff ”is stored and“ ← 100 → ”
"Ff ff ff ff
11 ff 21 20 20 ff 12 ff f
ff ff ”is stored, and fifteen consecutive“ ff ”are stored as space data in the fifth row.

The above-mentioned "ff" is character data for displaying a space (blank portion) connecting "F" in the horizontal direction and "F" in the vertical direction in the example of the character map shown in FIG. Similarly, “20” is a character displaying the font “O”, “3b” is a character displaying the font “S”, and “2d” is a character displaying the font “D”.

Therefore, by referring to the character map based on the character data read from the ROM 1, characters "OSD VPOSION", a horizontal line "-", a sign or numerical value "← 100 →" are displayed on the CRT screen. Such characters can be displayed with a space (blank portion) above and below the character display area.

[0008]

According to the conventional video display apparatus, when displaying a character in the character display area P1 of m rows.times.n characters / line, m characters.times.n characters / line. A ROM 1 having a memory area is provided.
In 1, space data is stored as a character data string in units of rows, and character data strings such as character display data including horizontal data, horizontal line display data, and code display data are stored in units of lines.

For this reason, despite the space data having the same contents in advance, the corresponding space data for a plurality of lines is stored in the ROM 1 as it is, or a large amount of space data is contained in one line of character data string. Since the character display data, the horizontal line display data, and the code display data are stored as they are, not only is the memory area of the ROM 1 used wastefully, but also the memory capacity must be increased.

In view of the above, the present invention has been made to solve the above-mentioned conventional problem. In the case where an arbitrary character is displayed in a predetermined character display area, the font table can be compressed and the font table can be compressed. It is an object of the present invention to provide a video display device with a character display function and a video display method, which can greatly reduce the memory capacity of the video display device.

[0011]

SUMMARY OF THE INVENTION The above-mentioned problem is solved by providing a character display function for displaying an arbitrary character in a character display area of m lines.times.n characters / line based on a font table from which a character data string is read out line by line. Storage means for storing a font table data-compressed line by line, and a command table for restoring the compressed font table, and an image display device based on the command table stored in the storage means. And a restoring means for restoring the font table in units of lines.

According to the video display device with the character display function according to the present invention, when an arbitrary character is displayed in the character display area of m lines × n characters / line, the font table data-compressed line by line is used. The restoration unit restores the original line-by-line font table based on the command table stored in the storage unit.

Therefore, as compared with the case where the font table is created without data compression, even when the command table and the data-compressed font table are stored together, the data of the blank portion where the character is not displayed and the data of the data are stored. Since the font table can be compressed in advance so that columns are deleted in rows, the memory occupied area can be reduced.

A video display method according to the present invention is a video display method for displaying an arbitrary character in a character display area of m lines × n characters / line based on a font table from which a character data string is read out line by line. In addition, a font table is compressed in units of lines in advance, and a command table for restoring the compressed font table is created, and when displaying characters, the font table is restored in units of lines based on the command table. Is what you do.

According to the video display method of the present invention, the character is displayed even when the command table and the data-compressed font table are created and stored, as compared with the case where the font table is created without data compression. Since the font table can be compressed in advance so as to delete the data of the blank portion not to be used and the data string in units of rows, the memory occupation area can be reduced. Thus, the memory capacity for the font table can be significantly reduced.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a video display device with a character display function and a video display method according to the present invention will be described with reference to the drawings. (1) Embodiment FIG. 1 is a block diagram showing a configuration example of a video display device with a character display function as an embodiment. In this embodiment, when an arbitrary character is displayed in a character display area of m rows × n characters / line, a font table data-compressed for each line is restored to an original font table for each line based on a command table. The font table can be compressed so as to delete the data of the blank portion in which the character is not displayed and the data string in units of lines, and the memory capacity for the font table can be significantly reduced. It was made.

The character display function (On Scr) shown in FIG.
A video display device 100 with an een display (hereinafter referred to as OSD) displays an arbitrary character in a character display area of m rows × n characters / line of a display unit based on a font table from which character data is read out line by line. It is.

The image display device 100 has a microcomputer (hereinafter referred to as a microcomputer) 10. A ROM (read only memory) 11, which is an example of a storage unit, is provided inside the microcomputer 10, and a font table T1 in which data is compressed line by line and a command table for restoring the compressed font table T1 T2 is stored.

Here, the font table T1 is m rows ×
In an n-character / line character display area P1 (see FIG. 4), a character data string for m lines required to display an arbitrary character. The character data sequence is a data sequence in which character data of n characters are arranged per line. For example,
In the example shown in FIG. 9, space data D1, font data D2, bar data D3, numerical data D4, and the like are stored as character data strings. The font table T1 is compressed so as to delete the data in the blank portion where the character is not displayed from the character data string for one line. At the same time, the data string in the blank portion where the character is not displayed is compressed so as to be deleted line by line.

The command table T2 is data used to restore the data-compressed line-by-line font table T1 to the original line-by-line font table T1. As for the command table T2, one line of character data string is replaced with one byte of command data for each line.

Inside the microcomputer 10, in addition to the ROM 11, a CPU (Central Processing Unit) 13 and a RAM (Writable and readable memory) 12 are provided. This R
The AM 12 and the CPU 13 constitute a restoring unit. When an input for performing OSD display is made, the
The original font table data for each line is restored based on the command table T2 stored in M11. The RAM 12 is used to temporarily store restored font table data (hereinafter, also referred to as RAM data D5) such as blank display data D11, character display data D21, horizontal line display data D31, and code display data D41. , Functions as a transmission (transfer) buffer to the RAM 22 of the OSD conversion circuit 20.

An OSD conversion circuit 20 is connected to the microcomputer 10 through a data bus 60, and a RAM data D5
Is converted into, for example, bitmap image data D6. The OSD conversion circuit 20 has a ROM 21 and a RAM 22. The ROM 21 stores a character map as shown in FIG. Regarding the data conversion at this time, the blank display data D11 and the character display data D
21, RAM data D5 such as horizontal line display data D31 and code display data D41 are used as addresses, and bitmap formats such as numbers, Roman characters, Chinese characters, symbols, codes, katakana characters, and line figures shown in the character map of the ROM 21 are used. The image data D6 is read. For example, when the RAM data D5 is "ff", the image data D6 displaying a blank character or a blank portion is read, and the RAM data D5 is read.
If 5 is "3b", the image data D6 displaying the font "S" is read.

A video processing circuit 30 is connected to the OSD conversion circuit 20, and receives the converted image data D6 and RGB signals for color display. Video processing circuit 3
At 0, bitmap image data D6 such as numbers, roman characters, kanji, symbols, codes, katakana characters, and line figures are superimposed on the RGB signals, and, for example, an NTSC video signal SOUT is created. The video processing circuit 30 has a CR
A T (cathode ray tube) 40 is connected, and a horizontal
A vertical deflection circuit is connected. In the CRT 40, the electron beam is subjected to horizontal and vertical deflection control, and an “OSD VPOSION” is displayed on the screen by the video signal SOUT.
Character, a horizontal line "-", a sign or numerical value "← 100 →" are displayed with spaces above and below in the character display area P1.

Next, an example of data storage in the ROM 11 will be described. The ROM 11 shown in FIG. 2 is provided with a font table T1 and a command table T2. Explaining with the example shown in FIG. 10, “ff” is 15 as blank display data D11 in the font table T1.
Continuous space data D1, character display data D21
Compressed “20 3b 2d ff3e 38 20 3b 3” indicating “OSD VPOSION” as
Font data D2 composed of “2 3c 32 20 37”, and “15” compressed as horizontal line display data D31.
16 16 16 16 16 16 16 16 1d "
The compressed "11 ff" indicating "← 100 →" as the bar data D3 composed of
Numerical data D4 composed of “21 20 20 ff 12” is described.

In the command table T2, a command = 00 (C
MD SPACE), similarly, command = 01 (CMD FONT) is described as a control instruction on the second line, and command = 02 is described as a control instruction on the third line.
(CMD BAR) is described, a command = 03 (CMD NUMBER) is described as a control instruction on the fourth line, and a command = 00 (CMD) is described as a control instruction on the fifth line.
SPACE) is described.

Next, an example of the relationship between various commands and their display contents and an example of replacing the font table T1 with 1-byte command data will be described. The command = 00 (CMD SPACE) shown in FIG.
Display all characters in the space data D1. . In the first line of the restored font table T1 shown in FIG. 3B, in which the blank display data D11 composed of 15 consecutive "ff" s is replaced with 1-byte command data. is there. This command = 00 (CM
When a plurality of D SPACEs are required in the character display area P1, only one representative of the space data D1 is described in the font table T1.

Similarly, command = 01 (CMD F
ONT) says, "Display characters in the relevant line."
For example, “ff 20 3b 2
dff 3e 38 20 3b 32 3c 32
20 37 ff ”in the character display data D21
It is replaced with byte command data. In the font table T1, font data (character data string) D2 obtained by removing “ff” from before and after the character display data D21 is described.

Command = 02 (CMD BAR)
Is a control command for “display a bar in the corresponding line.” For example, “ff ff ff 15 16
16 16 16 16 16 16 1d ff
The horizontal line display data D31 of “ff ff” is replaced with 1-byte command data. In the font table T1, bar data (character data string) D3 excluding “ff” from before and after the horizontal line display data D31 is described.

Command = 03 (CMD NUMB
ER) is a control command for “display a number in the corresponding line.” For example, “ff ff ff ff
11 ff 21 20 20 ff 12 ff
ff ff ff ”is replaced with 1-byte command data. The font table T1 includes “f” from before and after the code display data D41.
Numerical data (character data string) D4 excluding "f" is described. Thus, a total of two “ff” before and after the character display data D21, a total of four “ff” before and after the horizontal line display data D31, and a total of eight “ff” before and after the sign display data D41.
"Ff", 15 overlapping blank display data D11
Is reduced from the memory area.

Next, with respect to the video display method according to the present invention, an operation example of the video display device 100 having a character display function will be described. FIG. 4 is an image diagram showing a character display example on the CRT screen as the first embodiment. FIG. 5 is an image diagram showing an example of data processing by the CPU 13 when restoring the font table. FIG. 6 shows a PAD (Problem) showing an example of an algorithm at the time of data processing.
(Analysis Diagram) FIG.

In this embodiment, a character data string is read from the font table based on the command data. The character data string is read from the font table T1 on a line-by-line basis. It is assumed that, when an arbitrary character is displayed in the character display area P1 of / line, the font table T1 compressed in units of lines is restored based on the command table T2. M for the character display area P1
= 5, n = 15 as an example.

Assuming this, first, when the horizontal synchronizing signal HS and the horizontal synchronizing signal VS are input to the microcomputer 10 and there is an input for performing the OSD display, the steps of the algorithm shown in FIG. In A1, command data for restoring the font table T1 on the first to fifth lines and a compressed character data string are set for the character display area P1 on the CRT screen.

In this example, in the ROM 11 shown in FIG. 5, the command data on the first line is 00 (CMD SPA).
CE), and the command data on the second line is 01 (CM
D FONT), and the command data on the third line is 0
2 (CMD BAR), the command data on the fourth line is 03 (CMD NUMBER), and the command data on the fifth line is 00 (CMD SPACE).

In the compressed character data string, space data D1 consisting of 15 consecutive "ff" s is described as blank display data D11, and "2"
03b 2d ff 3e 38 20 3b 32
Font data D2 composed of "3c 32 20 37"
Is "OSD VPOSION" character display data D2
1 and “15 16 16 16 16
The bar data D3 composed of “16 16 161d” is described as horizontal line display data D31, and “2120 20
ff 12 ”is“ ← 100 ”
→ ”is described as code display data D41.

Next, when restoring the font table T1 on the first line of the character display area P1, the type of command data in the font table T1 is determined in step A2 of the algorithm in FIG. At this time, FIG.
Referring to the first line of the command table T2 shown in FIG.
00 (CMD SPACE) is described as command data. Therefore, in order to restore the first line, in step A3 of the algorithm in FIG.
Based on the “CMD SPACE”, space data D1 in which 15 “ffs” continue are set in the transmission buffer on the RAM 12 from the font table T1 on the ROM 11. As a result, the blank display data D11 in which 15 “ff” are continuous is restored.

Thereafter, in order to process the next line in step A4, the flow returns to step A2 to determine the type of command data in the font table T1 for restoring the second line. At this time, referring to the second line of the command table T2 shown in FIG. 5, 01 (CM
D FONT) is described. Therefore, in order to restore the second line, RO is executed based on the command data = “CMD FONT” in step A5 of the algorithm in FIG.
From the font table T1 on M11 to RAM12,
"20 3b 2d ff 3e 38 20 3b
32 3c 3220 37 "is set. At this time, "ff" read from the register is added one by one before and after the font data D2. Thereby, “ff 203b 2d ff
3e 38 20 3b 32 3c 32 203
The character display data D21 composed of “7 ff” is restored.

Thereafter, in order to process the next line in step A4, the flow returns to step A2 to determine the type of command data in the font table T1 for restoring the third line. At this time, referring to the third line of the command table T2 shown in FIG.
D BAR) is described. Therefore, in order to restore the third line, the ROM 1 is read out based on the command data = “CMD BAR” in step A6 of the algorithm in FIG.
1 from the font table T1 on the RAM 12
16 16 16 16 16 16 16 16 1d "
Is set. At this time, "f" read from the register before and after the bar data D3.
f "are added three by three. As a result, “ff ff
ff 15 16 16 16 16 16 16 16
16 1d ff ff ff ”is restored.

Thereafter, in order to process the next line in step A4, the flow returns to step A2 to determine the type of command data in the font table T1 for restoring the fourth line. At this time, referring to the fourth line of the command table T2, 03 (CMD NUM
BER) is described. Accordingly, in order to restore the fourth line, the ROM 1 is read out based on the command data = “CMDNUMBER” in step A7 of the algorithm in FIG.
1 from the font table T1 on the RAM 12
ff 21 20 20 ff 12 ”is set. At this time, the numerical data D4
Before and after, "ff" read from the register is added four by four. Thereby, “ff ff ff ff
11ff 21 20 20 ff 12 ff ff
ff ff ”is restored.

Thereafter, in order to process the next line in step A4, the flow returns to step A2 to determine the type of command data in the font table T1 for restoring the fifth line. At this time, referring to the fifth row of the command table T2, 00 (CMD SPA
CE) is described. Therefore, in order to restore the fifth line, the ROM 11 is read based on the command data = “CMD SPACE” in step A3 of the algorithm in FIG.
"Ff" is stored in the RAM 12 from the font table T1 above.
Are set to 15 consecutive space data D1.

As a result, character data strings such as space data D1, font data D2, bar data D3, and numerical data D4 on the ROM 11, and command data = 00 (CMD SPACE), 01 (CMD FO)
NT), 02 (CMD BAR), 03 (CMD NU)
For example, the font table T1 necessary for the character display area P1 of 5 lines × 15 characters / line can be restored (converted) from the MBER), and the font of 5 lines × 15 characters / line can be stored in the transmission buffer on the RAM 12. Table data can be written.

When the data restoration processing for five rows is completed, the process proceeds to step A8 of the algorithm in FIG.
Font table data (RAM data) D5 for 5 characters
Is transferred (transmitted) to the RAM 22 of the OSD conversion circuit 20. Therefore, in the OSD conversion circuit 20, for example, “ff”
Are converted to the NTSC bitmap image data D6.

Further, “ff 203 b 2d ff
3e 38 20 3b 32 3c 32 203
7ff ”is displayed in the same manner as“ OS
It is converted into image data D6 of “DVPOSION”.
“Ff ff ff 1516 16 16 16 1
The horizontal line display data D31 of “6 16 16 1d ff ff ff” is converted into image data D6 of “−”. “Ff ffff ff 11 ff 21 20
The code display data D41 of “20 ff 12 ff ff ffff” is converted into image data D6 of “← 100 →”.

The converted NTSC image data D
6 is superimposed on the RGB signal and output to the CRT 40.
In the CRT 40, under the horizontal and vertical deflection control, the characters "OSD VPOSION", the horizontal line "-", the sign and the numerical value "← 100 →" are displayed on the screen with spaces above and below in the character display area P1. Is done.

As described above, according to the video display device 100 with the character display function according to the present embodiment, the “OSD VPO” is displayed in the character display area P1 of 5 lines × 15 characters / line.
"SON" character, "-" horizontal line, "← 100"
When displaying a character consisting of a sign or a numerical value such as “→”, a font table T1 data-compressed line by line.
Is restored to the original line-by-line font table T1 by the CPU 13 based on the command table T2 stored in the ROM 11.

Therefore, compared with the case where the font table T1 is generated without data compression, the command table T
2 and the data-compressed font table T1 are generated and stored, the space data D1 of the blank portion not displaying the character is deleted in units of one line, and "ff" is deleted in character units from the character data string. Since the font table T1 can be compressed in advance, the memory occupied area can be reduced.
Thus, the memory capacity of the font table ROM 11 can be significantly reduced.

(2) Second Embodiment FIG. 7 is an image diagram showing an example of data restoration as a second embodiment. In this example, the character data string is read based on the command data, and the character data string is sequentially read from the font table in accordance with the description order of the command data. For example, 6 rows x 1
This is a case in which the characters "OSD VPOSION", the horizontal line "-", and the characters consisting of the sign or numerical value "← 100 →" described in the first embodiment are displayed in the character display area P2 of 5 characters / line. "OSD VPOSIO
It is assumed that a space (blank portion) is inserted between the character "N" and the horizontal line "-".

Although the font table T1 is described in the ROM 11 of the microcomputer 10 in this example in the same manner as in the first embodiment, the command table T21 differs from the first embodiment in the first line. Command data = 00 (CMD SPACE) is described as a control instruction indicating a restoration condition, and command data = 01 as a control instruction on the second line.
(CMD FONT) is described, command data = 00 (CMD SPACE) is described as a control instruction on the third line, and command data = 00 (CMD SPACE) is described as a control instruction on the fourth line.
02 (CMD BAR) is described, and command data = 03 (CMD NUMBE)
R) is described, and command data = 00 (CMD SPACE) is described as a control instruction on the sixth line.

That is, a control command for inserting the space data D1 between the second and third lines is described. When the font table T1 shown in the first embodiment is restored based on the command table T21, spaces (blank portions) are inserted above and below the character display area in the transmission buffer on the RAM 12 shown in FIG. , A space (blank portion) is inserted between the character "OSD VPOSION" and the horizontal line "-".
It is possible to display a character "OSD VPOSION", a horizontal line "-", and a character consisting of a sign or a numerical value "← 100 →".

Further, 00 (CMD SPACE) is stored as command data in the third line of the command table T21.
By just adding one byte, "OSD VPOSIO
A space (blank portion) can be inserted between the character "N" and the horizontal line "-". Also, “ff” is 1
Only five rows of blank display data D11 need to be described in the ROM 11 for one row. Therefore, in the second embodiment, the memory capacity for the other two rows of space data can be reduced.

(3) Third Embodiment FIG. 8 is an image diagram showing an example of data restoration as a third embodiment. In this example, when the reading order of the character data strings is changed, the description order of the command data is changed. For example, in the character display area P1 of 5 lines × 15 characters / line, “O” described in the first embodiment is used.
"SD VPOSION", "-" horizontal line,
"OSD VPOSION" is used to display a character consisting of a sign "← 100 →" or a numerical value.
It is assumed that characters and spaces (blanks) are exchanged.

Although the font table T1 is described in the ROM 11 of the microcomputer 10 in this example in the same manner as in the first embodiment, the command table T31 is different from the first embodiment in the first line. Command data = 01 (CMD FONT) is described as a control command indicating a restoration condition, and command data = 00 is set as a control command on the second line.
(CMD SPACE) is described, command data = 02 (CMD BAR) is described as a control instruction on the third line, and command data = 0 is written as a control instruction on the fourth line.
3 (CMD NUMBER) is described, and command data = 00 (CMD SPAC) is used as a control instruction on the fifth line.
E) is described.

That is, the command data is described so that the control commands on the first and second lines are exchanged. When the font table T1 shown in the first embodiment is restored based on the command table T31, a space (blank portion) is inserted below the character display area in the transmission buffer on the RAM 12 shown in FIG.
A space (blank portion) is inserted between the character “OSD VPOSION” and the horizontal line “−”.
"D VPOSION", horizontal line "-", "←
It is possible to display a character consisting of a sign or a numerical value of “100 →”.

Moreover, the command table T3 shown in FIG.
As for command No. 1, the command data in the first row of the command table T2 in FIG. 4 = 00 (CMD SPACE) and the second
By simply rewriting the command data on the line = 01 (CMD FONT), the display data on the two lines can be easily exchanged.

In each of the embodiments described above, the case where a character is displayed on the CRT screen has been described. However, the present invention is not limited to this, and a video display device with a character display function provided with a flat display element such as a liquid crystal display. The same effect can be obtained in

[0055]

As described above, according to the video display device with the character display function according to the present invention, the font table data-compressed line by line is converted to the original font table line-by-line based on the command table. Restoring means for restoring is provided. With this configuration, even if the command table and the data-compressed font table are stored, compared to the case where the font table is stored without data compression, the data of the blank portion that does not display the character or the data of the blank portion is stored. Since the font table can be compressed in advance so that columns are deleted in rows, the memory occupied area can be reduced.

According to the video display method of the present invention, the font table is compressed in units of lines in advance, and a command table for restoring the compressed font table is created. The font table is restored based on the command table. With this configuration, it is possible to compress the font table in advance so that the character data is not displayed in a blank portion or the data string of the blank portion is deleted in units of lines, so that the memory capacity for the font table is significantly reduced. can do. The invention is based on characters,
TV with character display functions such as symbols and diagrams,
It is very suitable for application to monitors, liquid crystal displays and the like.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration example of a video display device with a character display function as an embodiment.

FIG. 2 is an image diagram showing an example of data storage in a ROM 11;

3A is a table showing an example of the relationship between various commands and their display contents, and FIG. 3B is an image showing an example of replacing the font table T1 with 1-byte command data.

FIG. 4 is an image diagram showing a character display example on a CRT screen as the first embodiment;

FIG. 5 is an image diagram showing an example of data processing by a CPU 13 when restoring a font table.

FIG. 6 is a PA showing an example of an algorithm at the time of data processing;
FIG.

FIG. 7 is an image diagram showing an example of data restoration as a second embodiment.

FIG. 8 is an image diagram showing an example of data restoration as a third embodiment.

FIG. 9 is an image diagram showing a character display example on a CRT screen according to a conventional method.

FIG. 10 is an image diagram showing an example of data storage in a ROM 1 according to a conventional method.

FIG. 11 is an image diagram showing an example of a character map.

[Explanation of symbols]

10: microcomputer, 11: ROM (storage means),
12 RAM (restoring means), 13 CPU (restoring means), 20 OSD conversion circuit, 30 video processing circuit, 40 CRT, 50 horizontal / vertical deflection Circuit, 100 ... Video display device

Claims (11)

[Claims] 1. A video display device with a character display function for displaying an arbitrary character in a character display area of m lines × n characters / line based on a font table from which character data is read out line by line. Storage means for storing a font table compressed in units of data and a command table for restoring the compressed font table; and restoring the original line-unit font table based on the command table stored in the storage means A video display device with a character display function. 2. The character display function according to claim 1, wherein the font table is compressed so that data of a blank portion in which the character is not displayed is deleted from a character data string of one line. With video display. 3. The video with a character display function according to claim 1, wherein the font table is compressed so that a data string of a blank portion that does not display the character is deleted on a line-by-line basis. Display device. 4. The video display device with a character display function according to claim 1, wherein in the command table, the character data string is replaced with one-byte command data for each row. 5. A video display method for displaying an arbitrary character in a character display area on the basis of a font table in which a character data string is read out in units of lines, wherein the font table is compressed in units of lines in advance.
A video display method comprising: creating a command table for restoring the compressed font table; and restoring the font table on a line basis based on the command table when displaying the character. 6. The video display method according to claim 5, wherein the font table is compressed so that data of a blank portion in which the character is not displayed is deleted from a character data string of one line. . 7. The video display method according to claim 5, wherein the font table is compressed so that a data string of a blank portion that does not display the character is deleted on a line-by-line basis. 8. The video display method according to claim 5, wherein in the command table, the character data string is replaced with one-byte command data on a line-by-line basis. 9. The video display method according to claim 8, wherein a character data string is read from the font table based on the command data. 10. A character data string is read based on the command data, wherein the character data string is sequentially read from the font table in accordance with the description order of the command data. Video display method. 11. The video display method according to claim 10, wherein when changing the reading order of the character data string, the description order of the command data is changed.