JP2004061654A - Character display control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce an occupied area of a memory area of OSDRAM by information characters that are not displayed. <P>SOLUTION: This character display control device is provided with a blank character length information detecting circuit 19 for detecting whether a blank code indicating a blank part wherein no character to be displayed exists, is included in the character code or not, and a flip flop 20 for stopping displaying clock signals inputted to a display output control circuit 15 by the number of pixels in the display region indicated by the blank code, when the blank code is detected. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a character display control device that displays a channel, a volume, a menu, and the like on a screen of a display device such as a television with characters including characters, numerals, symbols, and the like.
[0002]
[Prior art]
Generally, an OSD (On Screen Display) circuit is used in a character display control device that displays a character on a screen of a television or the like. The OSD circuit sets a display area consisting of a specified number of pixels in the horizontal and vertical directions on the display screen in accordance with the horizontal synchronization signal and the vertical synchronization signal as a range of one character image, and sets a character string (referred to as “OSD Character). FIG. 9 is a block diagram showing the configuration of a conventional OSD circuit. In the figure, reference numeral 1 denotes a vertical position register for storing a value of a vertical display start position of an OSD character, and 2 denotes an OSD circuit which counts a horizontal synchronizing signal Hsync. A vertical display start position detecting circuit for detecting a vertical display start position of the character for use, a horizontal position register 3 for storing a value of a horizontal display start position of the character for OSD, and a counter 4 for counting the display clock OSC to detect the character for OSD. A horizontal display start position detection circuit 5 for detecting a horizontal display start position, a vertical display start position detection signal output from the vertical display position detection circuit 2, and a horizontal display start position detection output from the horizontal display start position detection circuit 4 Upon receiving the signal, a display output control circuit 6 for outputting a display command stores at least one line of OSD character codes. Upon receiving a display command output from the display output control circuit 5, the OSDRAM 7 that outputs a character code stores character data that is image data of a character corresponding to the character code, and receives a character code output from the OSDRAM 6. And an OSDROM 8 for outputting character data corresponding to the character code, and a shift register 8 for inputting and outputting character data in synchronization with a display command output from the display output control circuit 5.
[0003]
Next, the operation will be described.
First, the vertical display start position detection circuit 2 counts the horizontal synchronization signal Hsync and specifies the current vertical scanning position on the screen in order to detect the vertical display start position of the OSD character. Then, the current vertical scanning position is compared with the value stored in the vertical position register 1, and when they match, a vertical display start position detection signal is output to the horizontal display start position detection circuit 4 and the display output control circuit 5. .
[0004]
When receiving the vertical display start position detection signal, the horizontal display start position detection circuit 4 counts the display clock signal OSC in order to detect the horizontal display start position of the OSD character, and displays the current horizontal display position on the screen. Specify the scanning position. Then, the current horizontal scanning position is compared with the value of the horizontal position register 3, and if they match, a horizontal display start position detection signal is output to the display output control circuit 5.
[0005]
When the display output control circuit 5 receives the vertical display start position detection signal output from the vertical display start position detection circuit 2, the display output control circuit 5 specifies the order of the line to be displayed in the OSD character. The horizontal synchronization signal Hsync is counted, and the display line number is output to the OSDROM 7. Next, when the horizontal display start position detection signal output from the horizontal display start position detection circuit 4 is received, the count of the display clock OSC is performed to specify the number of the OSD character to be displayed. And outputs the display character number to the OSDRAM 6.
[0006]
The OSDRAM 6 outputs a character code corresponding to the display character number output from the display output control circuit 5 to the OSDROM 7. The OSDROM 7 outputs the character data corresponding to the display line number output from the display output control circuit 5 to the shift register 8 as parallel data. The shift register 8 converts the character data output from the OSDROM 7 from parallel data to serial data in synchronization with the display transfer clock signal output from the display output control circuit 5, and outputs the converted data to a display unit (not shown). To display the OSD character on the screen.
[0007]
FIG. 10 shows an example of character data displayed on the screen corresponding to nine character codes of character numbers 1 to 9 by the character display control device of FIG. As shown in this figure, the character codes "00", "01", "02", and "03" correspond to the character data "A", "B", "C", and "D", respectively. I have. “FF” including five character codes indicates a blank code indicating a blank portion where no character to be displayed exists.
[0008]
As described above, in the conventional character display control device, when there is a blank portion in which no character to be displayed exists, a blank code corresponding to the number of characters not to be displayed is included in the character code and stored in the OSDRAM 6. I was
[0009]
[Problems to be solved by the invention]
Since the conventional character display control device is configured as described above, if there are continuous blank portions where there is no character to be displayed, the blank code must be increased as the display area increases, and no display is performed. There is a problem that much of the memory area of the OSDRAM is occupied by character information. In addition, when the number of blank codes increases, the number of processes for detecting each blank code and setting a blank portion where no character is present increases, which hinders the original character display process. .
[0010]
Furthermore, since the number of characters in one line of the OSD characters is limited, when the frequency of the display clock signal increases, the dot density in the horizontal direction increases as shown in FIG. There is a problem that a non-displayable area where a character cannot be displayed is generated on the right side of the character.
[0011]
SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem. Even when a large number of blank portions in which no character to be displayed exists continuously, the memory area of the OSDRAM is occupied by information of the character not to be displayed. It is an object of the present invention to obtain a character display control device which reduces the number of characters and does not hinder the display processing of the original character.
It is another object of the present invention to provide a character display control device that does not generate a non-displayable area even when the blank of a display clock signal becomes high.
[0012]
[Means for Solving the Problems]
A character display control device according to the present invention includes a character image storage unit that stores image data of each character in correspondence with a character code, and a character image that temporarily stores a character code corresponding to at least one row of character strings. Code storage means, display output control means for giving the character code stored in the character code storage means to the character image storage means and outputting each pixel of the corresponding image data every time a display clock signal is input, and display output control means Blank detection means for detecting whether or not a blank code indicating a blank portion where no character exists is included in the character code, and is input to the display output control means when a blank code is detected by the blank detection means. Display clock signal by blank code By the amount of the blank of the display area that is is obtained by a configuration in which a clock signal control means for stopping.
[0013]
In the character display control device according to the present invention, the blank code in the character code storage means is configured to be data indicating the number of characters not to be displayed.
[0014]
In the character display control device according to the present invention, the blank code in the character code storage means is configured to be data indicating the number of pixels not to be displayed.
[0015]
The display output control means of the character display control device according to the present invention is configured to designate a display position of a first character in a character string to be displayed according to fixed position data indicating a horizontal display start position. is there.
[0016]
The character code storage means of the character display control device according to the present invention is configured to store a color code designating a display color of a character to be displayed and a display color of a display area corresponding to a character not to be displayed.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a configuration of an embodiment of the present invention will be described with reference to the drawings.
Embodiment 1 FIG.
FIG. 1 is a block diagram showing a configuration of an OSD (on-screen display) circuit of the character display control device according to the first embodiment. In the figure, reference numeral 11 denotes a value of a vertical display start position of an OSD character. A vertical position register 12 for counting a horizontal synchronization signal Hsync to detect a vertical display start position of the OSD character; and 13 a horizontal position register for storing a value of the horizontal display start position of the OSD character. , 14 is a horizontal display start position detecting circuit for counting the display clock OSC to detect the horizontal display start position of the OSD character, 15 is a vertical display start position detection signal output from the vertical display start position detection circuit 12, and When a horizontal display start position detection signal output from the horizontal display start position detection circuit 14 is received, A display output control circuit (display output control means) 16 for outputting a display command stores at least one line of OSD character codes, and outputs a character code when receiving a display command output from the display output control circuit 15. An OSDRAM (character code storage means) 17 stores character data (image data) corresponding to the character code, and receives a character code output from the OSDRAM 16 and outputs an OSDROM (character) corresponding to the character code. Image storage means), 18 is a shift register for inputting / outputting character data in synchronization with a display command output from the display output control circuit 15, and 19 is a blank character for detecting a blank character length code output from the OSDRAM 16. Longing A detection circuit (blank detection means), 20 is a flip-flop (clock signal control means) for controlling whether or not the display clock OSC (display clock signal) is input to the display output control circuit 15, and 21 is a blank character length information detection The counter 22 counts the display clock OSC by the number of dots (pixels) constituting the character of the blank character length code output from the circuit 19. The counter 22 controls the display clock OSC transmitted to the display output control circuit 15 by the flip-flop 20. Is an OSC transmission gate that inputs or stops input.
[0018]
Next, the operation will be described.
First, the vertical display start position detection circuit 12 counts the horizontal synchronization signal Hsync and specifies the current vertical scanning position on the screen in order to detect the vertical display start position of the OSD character. Then, the current vertical scanning position is compared with the value stored in the vertical position register 11, and when they match, a vertical display start position detection signal is output to the horizontal display start position detection circuit 14 and the display output control circuit 15. .
[0019]
Upon receiving the vertical display start position detection signal, the horizontal display start position detection circuit 14 counts the display clock signal OSC in order to detect the horizontal display start position of the OSD character, and displays the current horizontal display position on the screen. Specify the scanning position. Then, the current horizontal scanning position is compared with the value of the horizontal position register 13, and when they match, a horizontal display start position detection signal is output to the display output control circuit 15.
[0020]
When the display output control circuit 15 receives the vertical display start position detection signal output from the vertical display start position detection circuit 12, the display output control circuit 15 specifies the number of the line to be displayed in the OSD character. The horizontal synchronization signal Hsync is counted, and the display line number is output to the OSDROM 17. Next, when the horizontal display start position detection signal output from the horizontal display start position detection circuit 14 is received, the count of the display clock OSC is specified to specify the number of the OSD character to be displayed. And outputs the display character number to the OSDRAM 16.
[0021]
The OSDRAM 16 outputs a character code corresponding to the display character number output from the display output control circuit 15 to the OSDROM 17, and outputs a blank character length code to the blank character length information detection circuit 19. The OSDROM 17 outputs the character data corresponding to the display line number output from the display output control circuit 15 to the shift register 18 as parallel data. The shift register 18 converts the character data output from the OSDROM 17 from parallel data to serial data in synchronization with the display transfer clock signal output from the display output control circuit 15, and outputs the serial data to a display unit (not shown). To display the OSD character on the screen.
[0022]
The blank character length information detection circuit 19 receives the blank character length code output from the OSDRAM 16 and supplies a reset signal to the flip-flop 20 to display the display input to the display output control circuit 15 via the OSC transmission gate 22. The clock OSC is stopped, and the number of dots corresponding to the character of the blank character length code is set in the counter 21. The counter 21 counts down the set number of dots by the display clock OSC. When the count value becomes zero, the counter 21 supplies a set signal to the flip-flop 20 to output the display output via the OSC transmission gate 22. The input of the display clock OSC to the control circuit 15 is restarted.
[0023]
As a result, the display output control circuit 15 gives a display character number to the OSDRAM 16, outputs a character code to the OSDROM 17, gives a display line number to the OSDROM 17, and displays the character after the blank on the screen. If there is a plurality of blank portions in one character column, such a process of stopping the display clock OSC is performed according to the number of the blank portions.
[0024]
FIG. 2 shows a display example by the character display control device of the first embodiment. "00", "01", "02", and "03" are character data of "A", "B", "C", and "D", respectively, among five character codes of character numbers 1 to 5. , And one blank code “F5” corresponds to a blank portion that does not exist for five consecutive characters. Therefore, a blank portion in which only the blank code "F5" is detected once and no five characters are displayed is quickly set. That is, if there is a blank portion of an arbitrary number of characters in the character string to be displayed, a blank code indicating the number of characters of the blank portion is included in the character code and stored in the OSDRAM 16 and a dot corresponding to the number of characters is stored. The display clock OSC is stopped by the number.
[0025]
As described above, according to the first embodiment, if the character code includes a blank code indicating a blank portion where no character to be displayed exists, the number of characters in the blank portion indicated by the blank code is reduced. By stopping the display clock signal by the amount of the corresponding blank, that is, by the number of dots, the memory area of the OSDRAM 16 can be used for the information of the character not to be displayed even when many blank portions in which the character to be displayed does not exist continue. This has the effect of reducing occupancy and not hindering the original character display processing.
[0026]
Further, according to the first embodiment, since the blank code of OSDRAM 16 is data indicating the number of characters not to be displayed, even if the number of characters in a blank portion where there are no characters to be continuously displayed is changed, it is extremely simple. The effect that the character code data can be corrected is obtained. For example, in FIG. 2, when changing so that the blank portion does not exist continuously for nine characters, the blank code “F5” may be corrected to “F9”.
[0027]
Embodiment 2 FIG.
FIG. 3 is a block diagram showing the configuration of the OSD circuit of the character display control device according to the second embodiment. In the figure, reference numeral 23 denotes a blank dot length information detection circuit (blank detection means). Other components are the same as those of the first embodiment shown in FIG. 1, and are denoted by the same reference numerals, and description thereof will be omitted. However, the character code stored in the OSDRAM 16 includes a blank dot length code in dot units as a blank code of a blank portion in which no character is displayed.
[0028]
Next, the operation will be described.
The blank dot length information detection circuit 23 receives the blank dot length code output from the OSDRAM 16 and supplies a reset signal to the flip-flop 20, thereby displaying the display input to the display output control circuit 15 via the OSC transmission gate 22. The clock OSC is stopped, and the number of dots corresponding to the blank dot length code is set in the counter 21. The counter 21 counts down the set number of dots by the display clock OSC. When the count value becomes zero, the counter 21 supplies a set signal to the flip-flop 20 to output the display output via the OSC transmission gate 22. The input of the display clock OSC to the control circuit 15 is restarted.
[0029]
As a result, the display output control circuit 15 gives a display character number to the OSDRAM 16, outputs a character code to the OSDROM 17, gives a display line number to the OSDROM 17, and displays the character after the blank on the screen. When there are a plurality of blank portions in one row of character strings, the process of stopping the display clock OSC according to the period of the number of dots in each blank portion is performed according to the number of blank portions.
[0030]
FIG. 4 shows a display example by the character display control device according to the second embodiment. "00", "01", "02", and "03" are character data of "A", "B", "C", and "D", respectively, among five character codes of character numbers 1 to 5. And one blank code “F6” corresponds to a blank portion that does not exist for six dots continuously in the horizontal direction. That is, when there is a blank portion having an arbitrary number of dots in the character string to be displayed, a blank code indicating the number of dots of the blank portion is included in the character code and stored in the OSDRAM 16 and the display is performed for the number of dots. Clock OSC is stopped. In other words, an arbitrary number of dots that do not display a character can be inserted at an arbitrary position in the character data.
[0031]
As described above, according to the second embodiment, when the character code includes a blank code indicating a blank portion where no character to be displayed exists, the number of dots of the blank portion indicated by the blank code is determined. By stopping the display clock signal by the same amount, the same effect as in the first embodiment can be obtained. Further, according to the second embodiment, since the blank code of OSDRAM 16 is data indicating the number of pixels not to be displayed, by inserting an arbitrary number of dots at an arbitrary position of the character data, the blanking code of the display clock signal can be obtained. Even when the frequency is increased, by arbitrarily inserting a non-display dot between the displayed dots, the display dot density in the horizontal direction is adjusted, and an effect of preventing the non-display area from being generated is obtained.
[0032]
Embodiment 3 FIG.
FIG. 5 is a block diagram showing a configuration of an OSD circuit of the character display control device according to the third embodiment. In the figure, all components are the same as those of the first embodiment shown in FIG. , And the description thereof is omitted. However, the horizontal position register 13 and the horizontal display start position detection circuit 14 shown in FIG. 1 are not used in FIG.
[0033]
Next, the operation will be described.
In the third embodiment, since the horizontal display start position is fixed in advance, there is no need to detect the horizontal display start position of the OSD character by counting the display clock OSC. Therefore, as described above, the horizontal position register 13 and the horizontal display start position detection circuit 14 used in Embodiments 1 and 1 can be omitted. FIG. 6 shows a display example by the character display control device of the third embodiment. If there is a blank portion for two characters at the beginning of the character string to be displayed, and then display the characters "A", "B", "C", and "D", "F2", "00" , "01", "02", and "03" are stored. The subsequent operation is the same as in the first embodiment.
[0034]
As described above, according to the third embodiment, the same effects as those of the first embodiment can be obtained, and the display output control circuit 15 performs the display in accordance with the fixed position data indicating the horizontal display start position. Software for specifying the horizontal display start position, a register for storing the specified horizontal display start position, and a circuit for detecting the stored horizontal display start position. Is unnecessary, and an effect that a smaller circuit configuration and a character display program can be realized is obtained.
[0035]
Embodiment 4 FIG.
FIG. 7 is a block diagram showing a configuration of the OSD circuit of the character display control device according to the fourth embodiment. In the figure, reference numeral 24 denotes a color signal selection circuit. Other components are the same as those of the first embodiment shown in FIG. 1, and are denoted by the same reference numerals, and description thereof will be omitted. However, the OSDRAM 16 stores a character including a blank code of a blank portion in which no character is displayed, and a color code designating a display color of the character and the blank portion.
[0036]
Next, the operation will be described.
The OSDRAM 16 outputs the character code corresponding to the display character number output from the display output control circuit 15 to the OSDROM 17, outputs the blank character length code to the blank character length information detection circuit 19, and outputs the color code to the color signal selection circuit 24. Output to The color signal selection circuit 24 outputs an R signal, a G signal, and a B signal to a display unit (not shown) based on the color code output from the OSDRAM 16 to display a color OSD character on a screen.
[0037]
FIG. 8 shows a display example by the character display control device of the fourth embodiment. A color code is stored in the OSDRAM 16 corresponding to each character code. The color code is composed of “00: black”, “01: red (R)”, “02: green (G)”, “04: blue (B)”, “07: white” and others. In this example, a blank portion (blank code = F5) in which five characters are not displayed is displayed in blue.
[0038]
As described above, according to the fourth embodiment, the same effect as in the first embodiment can be obtained, and the color code for designating the display color of the character to be displayed and the display color of the display area corresponding to the character not to be displayed is provided. Is stored, the blank portion can be displayed in any designated color.
[0039]
【The invention's effect】
As described above, according to the present invention, the character display control device comprises: a character image storage means for storing image data of each character in correspondence with a character code; and a character code corresponding to at least one line of a character string. Character code storage means for temporarily storing a character code stored in the character code storage means to the character image storage means, and a display output for outputting each pixel of the corresponding image data for each input of the display clock signal Control means, a blank detection means for detecting whether or not a blank code indicating a blank portion where no character to be displayed exists is included in the character code, and if a blank code is detected by the blank detection means, The display clock signal input to the display output control means is Clock signal control means for stopping only the blank of the display area indicated by the code, so that even if there are many continuous blank portions where there are no characters to be displayed, even if there are many consecutive blank portions, there is no need to display information on characters not to be displayed. This has the effect of reducing the occupation of the memory area of the OSDRAM and not hindering the original character display processing.
[0040]
According to the present invention, the blank code in the character code storage means in the character display control device is configured to be data indicating the number of characters not to be displayed. Has the effect that character code data can be corrected very easily.
[0041]
According to the present invention, since the blank code of the character code storage means in the character display control device is configured to be data indicating the number of pixels not to be displayed, an arbitrary number of dots can be inserted at an arbitrary position in the character data. Accordingly, even when the frequency of the display clock signal is increased, there is an effect that a non-display area does not occur.
[0042]
According to the present invention, the display output control means of the character display control device is configured to specify the display position of the first character in the character string to be displayed according to the fixed position data indicating the horizontal display start position. This eliminates the need for software for specifying the horizontal display start position, a register for storing the specified horizontal display start position, and a circuit for detecting the stored horizontal display start position. There is an effect that a display program can be realized.
[0043]
According to the present invention, the character code storage means of the character display control device is configured to store the color code for designating the display color of the character to be displayed and the display color of the display area corresponding to the character not to be displayed. This has the effect that the blank portion can be displayed in any desired color.
[Brief description of the drawings]
FIG. 1 is a block diagram of an OSD circuit of a character display control device according to Embodiment 1 of the present invention.
FIG. 2 is a diagram illustrating a display example by the character display control device according to the first embodiment of the present invention.
FIG. 3 is a block diagram of an OSD circuit of the character display control device according to the second embodiment of the present invention.
FIG. 4 is a diagram illustrating a display example by the character display control device according to the second embodiment of the present invention.
FIG. 5 is a block diagram of an OSD circuit of the character display control device according to the third embodiment of the present invention.
FIG. 6 is a diagram illustrating a display example by the character display control device according to the third embodiment of the present invention.
FIG. 7 is a block diagram of an OSD circuit of a character display control device according to Embodiment 4 of the present invention.
FIG. 8 is a diagram illustrating a display example by the character display control device according to the fourth embodiment of the present invention.
FIG. 9 is a block diagram of an OSD circuit of a conventional character display control device.
FIG. 10 is a diagram showing a display example by a conventional character display control device.
FIG. 11 is a diagram illustrating a display example by a conventional character display control device when the frequency of a display clock signal is high.
[Explanation of symbols]
11 vertical position register, 12 vertical display start position detection circuit, 13 horizontal position register, 14 horizontal display start position detection circuit, 15 display output control circuit (display output control means), 16 OSDRAM (character code storage means), 17 OSDROM ( Character image storage means), 18 shift register, 19 blank character length information detection circuit (blank detection means), 20 flip-flops (clock signal control means), 21 counter, 22 OSC transmission gate, 23 blank dot length information detection circuit (blank) Detection means), 24 color signal selection circuit.

Claims (5)

A character display control device for displaying a character string with a display area consisting of a specified number of pixels in a horizontal direction and a vertical direction of a display screen according to a horizontal synchronization signal and a vertical synchronization signal as a range of one character image,
Character image storage means for storing image data of each character corresponding to the character code;
Character code storage means for temporarily storing a character code corresponding to at least one row of character strings;
Display output control means for giving a character code stored in the character code storage means to the character image storage means and outputting each pixel of corresponding image data for each input of a display clock signal;
Blank detection means for detecting whether or not a blank code indicating a blank portion where no character to be displayed is included in the character code;
A clock signal control unit that stops a display clock signal input to the display output control unit when the blank code is detected by the blank detection unit, by a blank of a display area indicated by the blank code. A character display control device. 2. The character display control device according to claim 1, wherein the blank code in the character code storage means is data indicating the number of characters not to be displayed. 2. The character display control device according to claim 1, wherein the blank code in the character code storage means is data indicating the number of pixels not to be displayed. The display output control means specifies a display position of a first character in a character string to be displayed according to fixed position data indicating a display start position in a horizontal direction. The character display control device according to claim 1. The character code storage means stores a color code for designating a display color of a character to be displayed and a display color of a display area corresponding to a character not to be displayed. Item display control device.

Images