JPH0895553A - Image display device - Google Patents

Abstract

PURPOSE: To simultaneously display both with a single display circuit by sharing a color palette between a character and a background image. CONSTITUTION: A background/character controller 11 outputs a coordinate specifying value on a picture, a read address of a background image ROM 12, a character number and a font coordinate. When an address generator 31 generates the read address of a font ROM 13, the character data of the font ROM 13 are inputted to an outer edge expander 30. The outer edge expander 30 generates the font co-ordinate, an outer edge flag and an outer edge co-ordinate, and generates the dot data of the outer peripheral part of the character stored in the font ROM 13. A write controller 14 selects the address of a background character VRAM 15 corresponding to the picture and the write data, and controls so that the background image and the character data are displayed simultaneously.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for superimposing a background still image or moving image and characters or characters on a television screen or the like, such as a karaoke device.
The present invention relates to an image display device that superimposes characters or characters composed of a plurality of colors on a background image.

[0002]

2. Description of the Related Art In recent years, image display devices have come to play an important role as information output devices from various devices. In particular, in a communication terminal such as a game, a so-called karaoke, or a captain system, it is becoming very common to output characters on a CRT display. In the case of karaoke, in most cases, a background image and lyrics are recorded together with a song on a disc-shaped recording medium such as an optical disc, and the voice and the image are output by reproducing the background image and the lyrics with an audio output device and an image output device. Is. In karaoke using such an optical disk, an optical head for reading information on the optical disk is required in the apparatus main body, and vibration resistance of the scanning mechanism system is required.

For this reason, some karaokes that are mounted on a vehicle or are small and portable have been proposed in which songs, background images, and lyrics are recorded in a semiconductor memory and the memory is carried or equipped. In such karaoke, the song data is transmitted by MIDI (Musical Instrument Digital Interface).
It manages with a standard interface to generate musical tones. As an image display device used for such a type of karaoke, for example, Japanese Patent Laid-Open No. 5-224
No. 684 discloses “Karaoke playing device”.

An example of the configuration of such a conventional image display device is shown in FIGS. 7 and 8 and will be described. 7 and 8 are block diagrams of a conventional image display device. 7 and 8, the image display device 100 includes a character display unit 110, a background image display unit 210, and an image switch 220.
The character display unit 110 shown in FIG. 7 is a circuit unit for generating a character image, and the background image display unit 210 is a circuit unit for generating a background image. The outputs of these are switched by the image switching unit 220, such as a CRT. Given to the display device.

Now, the character display unit 110 includes a character controller 11
1, font ROM 113, writing controller 114, character V
RAM 115, reading controller 116, color table 11
7, read address generator 118, video signal controller 11
It is composed of 9. In addition, the background image display unit 210 shown in FIG.
Is a background controller 211, a background image ROM 213, a writing controller 214, a background image VRAM 215, a reading controller 216,
A color table 217, a read address generator 218,
It is composed of a video signal controller 219.

FIG. 4 shows an example of data stored in the font ROM 113. This font data is a kind of what is called a grayscale font. When a so-called dot font is used, stair-shaped unevenness is generated in the diagonal line portion of the character, etc., making the character difficult to see. Grayscale fonts can alleviate this problem.

FIG. 4A shows a display code (data) of each dot when a hiragana "ka" is formed with a gray scale font. In FIG. 4, the display code <6> is the background color, the display codes <7> and <5> are the border color,
The display codes <0> to <4> are foreground colors. Figure 4 (a)
If only the outline color and foreground color are included in the data of
As shown in FIG. 4B, if only the foreground color is used, FIG.
Therefore, if only the border color is used, the result is as shown in FIG.

The foreground colors represented by the display codes <0> to <4> are, for example, <0> is white, <1> is slightly dark white, and <3>.
Is a little light gray, <4> is gray, and the display code is displayed from small to large, and the lightness is reduced in this order from white to gray. As can be seen from FIG. 4 (c),
In the grayscale font, the lightness is small at the ends of the lines forming the character, and the lightness difference from the background (black in this case) is also small. For this reason, even if stair-like unevenness occurs in the diagonal line portion of the character, etc., the unevenness is not noticeable because the difference in brightness between the foreground (character) and the background is small, and the character looks beautiful.

The operation of the conventional image display device for displaying such characters will be described. First, when a display character and a display position are designated in the character controller 111, the character controller 111 generates an address for reading the font data of the designated character and outputs it to the font ROM 113. In addition, the character controller 111 generates (X, Y) coordinates on the screen in which the character font data is written according to the designated display position, and outputs the (X, Y) coordinates to the writing controller 114. The (X, Y) coordinates are, for example, (X, Y) = (0,
0) is the coordinate system on the screen.

The data in the font ROM 113 designated and read by the character controller 111 and the character controller 111
The (X, Y) coordinates generated by are input to the write controller 114. The write controller 114 converts the (X, Y) coordinate value into the address of the character VRAM 115 for writing the character.
VR in which font data is written by associating (X, Y) coordinate values with the addresses of the character VRAM 115 in a one-to-one correspondence
The real address of AM 115 is determined.

The address of the character VRAM 115 is also sent to the reading controller 116. The reading controller 116 writes the data of the writing controller 114 in the character VRAM according to the timing signal from the video signal controller 119 (for example, the vertical blanking period). Also reading controller 116
Selects the VRAM address generated by the write controller 114 or the read address generator 118 based on the timing signal generated by the video signal controller 119, and selects the address of the character VRAM 115.

As a result, when writing data to the character VRAM 115, the output address of the write controller 114 is selected, and when sequentially reading the screen display data, the output value of the read address generator 118 is the character VRAM 115.
Address. The character data read from the character VRAM 115 becomes the table number of the color table 117. The color table 117 has, for example, eight color table numbers, and one color table number is associated with a set of (R, G, B) values.

Character data read from the character VRAM 115 is determined as a color table number (R,
The G, B) value is input to the video signal controller 119 and converted into a video signal. The video signal controller 119 supplies operation timing signals to the read address generator 118 and the reading controller 116. For example, (X, Y) = (0,0)
A timing signal is supplied to the read address generator 118 and the reading controller 116 so as to associate the coordinate system on the screen with the NTSC format video signal.

On the other hand, when the display background image is designated in the background controller 211, the background controller 211 generates an address for reading the designated background image data. In addition, the background controller 21
1 generates (X, Y) coordinates on the screen in which the background image data is written according to the designated display position. This (X,
For example, the (Y) coordinate is (X, Y) at the upper left corner of the TV screen
= (0,0) is the coordinate system on the screen.

The data of the background image ROM 212 designated and read by the background controller 211 and the (X, Y) coordinates generated by the background controller 211 are input to the write controller 214. In the writing controller 214, the (X, Y) coordinate value is used as the background image V.
It is converted into the address of the RAM 215. As a result, the (X, Y) coordinate value for displaying the background image is associated with the address of the background image VRAM 215 one-to-one, and the actual address of the VRAM 215 for writing the background image data is determined.

This background image VRAM address is sent to the reading controller 216. The reading controller 216 writes the data of the writing controller 214 to the background image VRAM 215 according to the timing signal from the video signal controller 219 (for example, the vertical blanking period). The reading controller 216 is
Based on the timing signal generated by the video signal controller 219, the write controller 214 or the read address generator 2
The VRAM address generated in 18 is selected, and the address of the background image character VRAM 215 is selected. This allows
When writing data to the background image VRAM 215, the output address of the writing controller 214 is selected, and when reading screen display data sequentially, the read address generator 21.
The output value of 8 becomes the address of the background image VRAM 215.

The background image data read from the background image character VRAM 215 becomes the table number of the color table 217. The color table 217 has, for example, 256 color table numbers, and one color table number is associated with a set of (R, G, B) values. The (R, G, B) values determined by using the background image data read from the background image VRAM 215 as the color table number are converted into a video signal by the video signal controller 219. The video signal controller 219 gives operation timing signals to the read address generator 218 and the reading controller 216, and the coordinate system on the screen where (X, Y) = (0, 0) is set to NTSC format video. Map to signals. Thus, the video signal controller 219 reads the timing signal and reads out the address generator 218 and the reading controller 216.
Supply to.

The output signal of the video signal controller 119 and the output signal of the video signal controller 219 are both input to the image switching device 220, and are switched and output by the superimpose signal YS output from the video signal controller 119. .

[0019]

However, in the above-mentioned conventional structure, the VR and the background image are independent of each other.
AM is required. In order to read and write these character VRAM 115 and background image VRAM 215 and generate video signals, write controllers 114 and 214, reading controllers 116 and 216, and video signal controllers 119 and 219, respectively.
Then, the read address generators 118 and 218 and the color tables 117 and 217 are required, which has a drawback that the circuit scale of the image display device becomes large.

In order to simplify these circuit configurations, if one VRAM is used for a character and a background image, some of the background color table 217 is used for specifying the character color or the color is specified. The size of the table must be enlarged as much as necessary to specify the font color. If some of the background image color tables are used to specify the character color, the number of color tables that can be used for the background image is reduced as a result.

Usually, 256 color tables are required to form a background image close to a natural image. From this viewpoint, in a normal image display device, the size of the color table is 256 colors, and the background image data is often created on the premise of 256 colors. In such a system, if eight color tables were used independently to specify the character color, the number of color tables that could be used in the background image would be reduced to 248, and the image quality of the natural image of the background image would be reduced. Damages. Also, even if you try to increase the color table by the amount necessary to specify the character color,
An image display device or the like integrated into a circuit has a problem that the number of color tables cannot be easily increased.

Since the grayscale font is based on the assumption that the background color is black, the grayscale font must be bordered with black in order to exhibit the beauty of the grayscale font. In other words, the gray scale font has a problem that the memory size of the font ROM is increased by the amount of the edging, while the unevenness at the diagonal line portion of the character is not noticeable.

When the display code <5> and the display code <7> shown in FIG. 4 (d) are simply blacked when edging the gray scale font, the unevenness of the edging is generated at the boundary between the background image and the edge. It also had the problem that it was noticeable.

The present invention has been made in view of the above conventional problems, and (1) without reducing the color table used in the background image and without deteriorating the quality of the background image, Reserve a color table for grayscale characters. (2) Compress the memory size of the font ROM for grayscale fonts. (3) Make the irregularities on the outside of the border of the font inconspicuous. An object of the present invention is to realize an image display device having the above three features.

[0025]

According to a first aspect of the present invention, there is provided an image display device for displaying characters on a screen together with a background image, the background image ROM storing a plurality of background images, and a plurality of character patterns. A font ROM that stores the data, screen coordinate values, the read address of the background image ROM, the character coordinate numbers of the characters and the font coordinate values that are the character data, and the background character controller that directly generates the display data, the character numbers and the font coordinates. An address generator that generates a read address of the font ROM from the value, a character color index that converts the character data read from the font ROM into a predetermined color table number, and font coordinate values and characters that are output from the background character controller. An outer edge expander that generates an outer edge flag and outer edge coordinates that are the contour pixels of the character from the data and inputs them to the background character controller, and A write controller to which the mark, the direct display data, the output of the character color index, and the data of the background image ROM are input, and the write address and the character data for writing and the background image data are output, and the write address of the write controller. And a VRA for selecting a read address and a VRA for writing and storing the output data of the write controller by controlling the address and read / write by the read controller.
M, a color table for converting the output data of the VRAM into a color table number, a video signal controller for converting the color designation value read from the color table into a video signal based on a video synchronization signal, and a video signal A read address generator which generates a read address of the VRAM based on a synchronization signal generated by the controller and outputs the read address to the reading controller. The reading controller and the writing controller are generated by the video signal controller. It is characterized in that a character is superimposed and displayed on a background image by controlling with a synchronizing signal.

The invention according to claim 2 of the present application is an image display device for displaying a character together with a background image on a screen, comprising a background image ROM for storing a plurality of background images, and a font ROM for storing a plurality of character patterns. , Screen coordinate values, background image ROM
, A background character controller for directly generating display data, a character coordinate number of a character and a font coordinate value to be character data, and an address generator for generating a read address of a font ROM from the character number and font coordinate value. , The outer edge flag and the outer edge coordinates that are the contour pixels of the character are determined from the character color index that converts the character data read from the font ROM into a predetermined color table number, and the font coordinate value and the character data that are output from the background character controller. The outer edge extender that is generated and input to the background character controller, the screen coordinates, the direct display data, the output of the character color index, and the background image ROM data are input, and the write address and the character data for writing and the background image are input. Select the write controller that outputs the data and the write address and read address of the write controller. Read / write controller, address and read / write are controlled by the read / write controller, VRAM for writing and storing output data of the write controller, color table for converting VRAM output data into color table number, and color table Based on the video signal controller that converts the read color specification value into a video signal based on the video synchronization signal, and the synchronization signal generated by the video signal controller,
A read address generator that generates a read address of the VRAM and outputs the read address to the reading controller, a sync detector that detects a sync signal from the external video signal, and a luminance control signal of the video signal controller so that the outer edge of the character is the external video signal. A brightness adjuster that controls to reduce the brightness of the external video signal when the color matches the color of, and an image switcher that switches the output of the brightness adjuster and the video output of the video controller with the image switch signal of the video controller, The video signal controller operates with the sync signal detected by the sync detector, and the reading controller and the writing controller are controlled by the sync signal of the video signal controller to superimpose characters on the background image. It is characterized by displaying as.

In the third aspect of the present invention, the outer edge expander stores the row start value Is when the row address is I and the column address is J in the memory address for each character in the font ROM. A first register, a second register in which the row end value Ie is stored, and a column start value J
s is stored in the third register, the column end value Je is stored in the fourth register, the row address I and the first comparator for comparing the output of the first register, the row address I and the A second comparator that compares the output of the second register, a third comparator that compares the column address J with the output of the third register, and a fourth comparator that compares the column address J with the output of the fourth register. And the outputs of the first and second comparators, Ib = Is-1 when Is = I and Ib = Ie = I
I-coordinate generators for outputting Ie + 1 and third and fourth I-coordinate generators, respectively.
With reference to the output of the comparator, when Js = J, Jb = Js−
1, J = Je + 1 when J = J, the J coordinate generator that outputs Jb = Je + 1 and the outputs of the first to fourth comparators are referred to as Is =
When any one of I, Ie = I, Js = J, and Je = J is satisfied, the end edge determination value output, which is the outer edge data of the font ROM, is determined to be true, and the inner edge value of the character data is stored. And a fifth register, a one-value detector that makes the one-value detection value true when the output of the fifth register and the pixel value of the character data have one value, an output of the one-value detector, and a general-end determiner And a flag generator that sets the outer edge flag to true when both outputs are true.

[0028]

According to the invention of claim 1 of the present application having such a feature, a color table number having (R, G, B) values close to colors used for characters is extracted in advance from the color table of the background image. And store it in the character color index. When displaying a character, the data in the font ROM is referred to by the character color index and converted into a color table number. The writing controller gives the character data output from the font ROM to the background character VRAM together with the background image data of the background image ROM, and writes each data through the reading controller based on the synchronizing signal of the video signal controller. . At this time, the data of the font ROM is stored by being compressed by omitting the pixel data of the outline portion of the character pattern. When displaying an image including characters on the screen, the outer edge expander detects the outer edge and extends the character data by adding the outer edge data. Therefore, it is possible to display a grayscale font with excellent image quality with a small ROM capacity.

According to the invention of claim 2 of the present application, in addition to the operation of the invention of claim 1, by reducing the luminance of the external video signal, grayscale of the edge is automatically performed and unevenness of the outer edge is obtained. Is inconspicuous and beautiful characters can be inserted.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An image display device according to an embodiment of the present invention will be described with reference to the drawings. 1 and 2 are block diagrams showing the overall configuration of the image display device 10 in this embodiment. 1 and 2, the image display device 10 is
Background character controller 11, background image ROM 12, font RO
M13, write controller 14, background character VRAM 15, reading controller 16, color table 17, read address generator 18, video signal controller 19, outer edge extender 30, address generator 31, character color index 32, sync detection. Bowl 33,
The image switch 34 and the brightness adjuster 35 are included.

FIG. 3 is a block diagram showing a specific structure of the outer edge dilator 30. In this figure, the outer edge dilator 30 is
The registers 41 to 44, the comparators 45 to 48, the I coordinate generator 49, the J coordinate generator 50, the overall edge determiner 51, the register 52, the coincidence detector 53, and the flag generator 54 are included. 4 to 6 are explanatory views showing the storage state of font data in this embodiment.

Next, the image display device 10 will be described in detail. First, the background character controller 11 generates a read address of the background image ROM 12, and also generates (X, Y) coordinates on the screen in which the background image data is written. The background character controller 11 also generates the address of the font ROM 13 for reading the font data of the designated character, and also generates the (X, Y) coordinates on the screen in which the character font data is written. Similar to the conventional example, these (X, Y) coordinates are a coordinate system on the screen where the upper left corner of the screen of the television is (X, Y) = (0, 0), for example.

The data of the background image ROM 12 designated and read by the background character controller 11 and the background character controller 11
The (X, Y) coordinates generated by are input to the write controller 14. In the writing controller 14, the (X, Y) coordinates are the background characters VR.
It is converted into the address of AM15.

The background character controller 11 is a font ROM.
The 13 addresses are generated in the following format. That is, the number of the character to be displayed (for example, JIS kanji code) and the row and column of each character data are designated, and the coordinates (font coordinates) in this matrix are set to (I, J). The character number and (I, J) coordinates are given to the address generator 31 and converted into a read address of the font ROM 13. Then, according to the address specified by the address generator 31, the font R
The character data read from the OM 13 is converted into a color table number by the character color index 32.

In the character color index 32, a color table number suitable for character display is extracted from the table numbers of the color table 17 used for the background image in advance and stored. For example, in the case of a gray scale font, achromatic color white to black is suitable for character display, and therefore the color table numbers of white to black may be extracted and stored in the character color index 32.

Character data is stored in the font ROM 13 as shown in FIG. 5 (d). That is, FIG.
(A) is single border data of a gray scale font, and the meaning of the display code is the same as in FIG. Figure 5
FIG. 5B is a diagram in which the outer edge is further added to (a), and the display code of the outer edge is <7>. As can be seen from FIGS. 5A and 5B, the number of dots forming the font is increased by adding the outer edge. In the format of FIG. 5A, for example, the character data of 8000 characters is 12.6M.
It can be stored with a bit storage capacity, but in FIG.
It will be 4.8 Mbits and the capacity difference will be 2.2 Mbits.

Here, paying attention to the upper, lower, left and right edges of the data in FIG. 5B, it can be seen that the display code is only <6> or <7>. In FIG. 5C, the display code <6> at the upper, lower, left and right ends is replaced with "." For easy viewing. From this, it is immediately understood that the display code at the end is <7>, that is, in the case of the outer edge, <5> is always inside the display code. Therefore, font ROM1
Except for this outer edge data, font data 3 is stored in the form of FIG. 5 (d).

Here, the explanation is returned to the operation of the circuit section shown in FIGS. The font data read from the font ROM 13 is also input to the outer edge expander 30 of FIG. 3, and it is determined here whether the outer edge <7> is omitted. This determination is performed as follows. In FIG. 3, the row start value Is is first given to the first register 41, and the row end value Ie is given to the second register 42. Similarly, the column start value Js is given to the third register 43, and the column end value Je is given to the fourth register 44.

Next, the row address I is given to the first comparator 45, the second comparator 46 and the I coordinate generator 49. Further, the column address J is given to the third comparator 45, the fourth comparator 46, and the J coordinate generator 50. The comparator 45 compares the output of the register 41 with the row address I, and supplies a match or mismatch signal to the I coordinate generator 49. Similarly, the comparator 46 compares the output of the register 42 with the row address I, and gives a match or mismatch signal to the I coordinate generator 49. Then, the I coordinate generator 49 outputs Ib = Is−1 when Is = I,
When Ie = I, Ib = Ie + 1 is output

Further, the comparator 47 compares the output of the register 43 with the column address J, and gives a coincidence or non-coincidence signal to the J coordinate generator 50. Similarly, the comparator 48 uses the register 44
And the column address J are compared, and a coincidence or non-coincidence signal is given to the J coordinate generator 50. And the J coordinate generator 5
0 is Jb = Js−1 when Js = J and J when Je = J
b = Je + 1 is output.

The overall edge determiner 51 includes comparators 45 to 48.
Is output, Is = I, Ie = I, Js = J, Je
= J is obtained, true (for example, an H level signal) is output as the end determination value output. When the fifth register 52 stores the inner edge value and the output of the register 52 and the display value match, the match detector 53 outputs true as the match detection value. The flag generator 54, when both the output of the coincidence detector 53 and the output of the overall edge determiner 51 are true,
Set the outer edge flag to true.

FIG. 6 shows only the inner edge <5> and the outer edge <7> of the contents of the font ROM 13 for easy viewing. (A) to (d) of FIG. 6 are respectively (a) of FIG.
Corresponds to (d). FIG. 5C, that is, FIG.
In the case of a font ROM stored as in (c), Js
= 0, Je = 22, Is = 0, Ie = 23, and the inner edge value is 5.

For example, when J = 0 and I is increased by 1 from 0, since J = Js, the J coordinate generator 50 outputs -1, and the I coordinate generator is other than when I = 0 or I = 23. Outputs I itself. Here, when I = 8, the display value is 5
Becomes equal to the inner edge value, and at this time, the total edge determiner 5
Since 1 outputs true, the outer edge flag becomes true. At this time, the outer edge <7> may be restored to Jb = −1 and Ib = 8.

In FIG. 1, the outer edge expander 30 has an outer edge <7>.
If the restoration is required, the outer edge flag is set to true, and further the outer edge <7> is restored and the coordinates (Ib, Jb) of the row and column of the character data to be added are output. The outer edge flag and the coordinates (Ib, Jb) are input to the background character controller 11, and if the outer edge flag is true, the background character controller 11 sets the coordinates (Ib, Jb).
Based on b), the (X, Y) coordinates for displaying the outer edge <7> are generated. Then, the color table number of the outer edge <7> is directly output to the writing controller 14 as the display data.

As described above, the writing controller 14 converts the (X, Y) coordinates into the address of the background character VRAM 15. The address of the background character VRAM 15 is sent to the reading controller 16. The reading controller 16 sets the data of the writing controller 14 to the background character V according to the timing signal from the video signal controller 19 (for example, the vertical blanking period).
Write to RAM15. Further, the reading controller 16 selects the address of the background character VRAM 15 generated by the write controller 14 or the read address generator 18 based on the timing generated by the video signal controller 19.

The background or character data read from the background image character VRAM 15 becomes the table number of the color table 17. The color table 17 has, for example, 256 color table numbers, and one color table number is associated with a set of (R, G, B) values.
The (R, G, B) values output from the color table 17 are input to the video signal controller 19 and converted into a video signal. The video signal controller 19 gives an operation timing signal to the read address generator 18 and the reading controller 16. The video signal controller 19 associates the coordinate system on the screen, for example, (X, Y) = (0, 0), with the video signal of the NTSC format, and reads this timing signal from the read address generator 18 and the reading controller 16 Supply to.

When superimposing a character on an external image, the sync detector 33 detects a sync signal (horizontal, vertical sync, color subcarrier, burst flag, etc.) of the external video from the external video signal. These synchronization signals synchronize the processing of the video signal controller 19 with the external video. When the output (R, G, B) value of the color table 17 matches the outer edge of the character, the video signal controller 19 generates a control signal to the brightness adjuster 35 so as to reduce the brightness of the external video. In addition, the output of the color table 17 (R,
When the G, B) values match the inner edge of the character and the entire scene, the image switch 34 is caused to select the output of the video signal controller 19, and otherwise the output of the brightness adjuster 35 is selected. The superimpose signal YS is generated.
As a result, the brightness of the external image is reduced at the outer edge of the character, so that the edge of the character is grayscaled, the unevenness of the edge becomes inconspicuous, and a beautiful edged character is displayed.

As described above, according to the present embodiment, the color table 17 is provided so as to be shared by the background image and characters, so that the VRAM, the color table, the video signal controller,
Since it is not necessary to have a read address controller and a reading controller for each of the background and the characters, the image display device can be constructed at low cost. If the background color is extremely biased and there is no achromatic color table, select a color table that is as close to achromatic as possible, and achromaticize that color table to improve the image quality of the background image. Deterioration can be minimized.

Although the character color index 32 is stored in advance in the embodiment, the character color index may be automatically rewritten when the background color table is rewritten.

[0050]

As described above, according to the present invention, a color table number having an RGB value close to a color used for a character is previously extracted from the background color table and stored in the character color index. . When displaying a character, the data in the font ROM serves as a reference number that refers to the character color index, and the character color index outputs the color table number used by the character data. Therefore, the characters can be displayed without changing the color table of the background image, so that the image quality of the background image is not deteriorated and the configuration of the image display device can be simplified.

Since the data in the font ROM is stored in a compressed form and is expanded by the outer edge expander, the gray scale font can be stored with a small ROM capacity. Furthermore, by detecting the outer edge of the character and lowering the brightness of the external video signal at the drawing timing of the outer edge,
The edges are grayscaled. Therefore, the unevenness of the outer edge of the character becomes inconspicuous, beautiful characters can be inserted, and a practically excellent effect can be obtained. Further, when such an image display device is used, a scanning mechanism portion which is weak in vibration resistance unlike the optical disk reproducing device is unnecessary, and a karaoke device which can be easily carried in a vehicle or a vehicle can be realized.

[Brief description of drawings]

FIG. 1 is a block diagram (No. 1) showing an overall configuration of an image display device in an embodiment of the present invention.

FIG. 2 is a block diagram (No. 2) showing the overall configuration of the image display device in the embodiment of the present invention.

FIG. 3 is a block diagram of an outer edge dilator provided in the image display device of this embodiment.

FIG. 4 is an explanatory diagram of a storage state (part 1) of font data in the present embodiment.

FIG. 5 is an explanatory diagram of a storage state (part 2) of font data in the present embodiment.

FIG. 6 is an explanatory diagram of a storage state (part 3) of font data in the present embodiment.

FIG. 7 is a block diagram (No. 1) showing a configuration example of a conventional image display device.

FIG. 8 is a block diagram (No. 2) showing a configuration example of a conventional image display device.

[Explanation of symbols]

 10 Image Display Device 11 Background Character Controller 12 Background Image ROM 13 Font ROM 14 Writing Controller 15 Background Image Character VRAM 16 Reading Controller 17 Color Table 18 Read Address Generator 19 Video Signal Controller 30 Outer Edge Extender 31 Address Generation Device 32 Character color index 33 Sync detector 34 Image switcher 35 Brightness adjuster 41 to 44, 52 Register 45 to 48 Comparator 49 I coordinate generator 50 J coordinate generator 51 Overall edge determiner 53 Match detector 54 Flag generator vessel

Claims (3)

[Claims] 1. An image display device for displaying characters together with a background image on a screen, comprising a background image ROM for storing a plurality of background images, a font ROM for storing a plurality of character patterns, coordinate values of the screen, and a background. The read address of the image ROM, the character number of the character and the font coordinate value that becomes the character data, and the background character controller that directly generates the display data, and the font RO from the character number and the font coordinate value.
From an address generator for generating a read address of M, a character color index for converting the character data read from the font ROM into a predetermined color table number, and font coordinate values and character data output from the background character controller. An outer edge expander for generating an outer edge flag and an outer edge coordinate to be a contour pixel of a character and inputting to the background character controller, screen coordinates, direct display data, output of the character color index, and the background image ROM. A writing controller for inputting data and outputting a writing address and the character data and background image data for writing; a reading controller for selecting a writing address and a reading address of the writing controller; and the reading controller. Address and read / write are controlled by
VRA for writing and storing output data of the write controller
M, a color table that converts the output data of the VRAM into a color table number, a video signal controller that converts the color designation value read from the color table into a video signal based on a video synchronization signal, A read address generator that generates a read address of the VRAM based on a sync signal generated by the video signal controller and outputs the read address to the VRAM, and the read controller and the write controller. Is controlled by a synchronization signal generated by the video signal controller to display the characters by superimposing them on the background image. 2. An image display device for displaying characters together with a background image on a screen, comprising a background image ROM for storing a plurality of background images, a font ROM for storing a plurality of character patterns, screen coordinate values, and a background. The read address of the image ROM, the character number of the character and the font coordinate value that becomes the character data, and the background character controller that directly generates the display data, and the font RO from the character number and the font coordinate value.
From an address generator for generating a read address of M, a character color index for converting the character data read from the font ROM into a predetermined color table number, and font coordinate values and character data output from the background character controller. An outer edge expander for generating an outer edge flag and an outer edge coordinate to be a contour pixel of a character and inputting to the background character controller, screen coordinates, direct display data, output of the character color index, and the background image ROM. A writing controller for inputting data and outputting a writing address and the character data and background image data for writing; a reading controller for selecting a writing address and a reading address of the writing controller; and the reading controller. Address and read / write are controlled by
VRA for writing and storing output data of the write controller
M, a color table that converts the output data of the VRAM into a color table number, a video signal controller that converts the color designation value read from the color table into a video signal based on a video synchronization signal, A read address generator for generating a read address of the VRAM based on a sync signal generated by the video signal controller and outputting the read address to the reading controller; and a sync detector for detecting the sync signal from an external video signal. A brightness adjuster for controlling the brightness of the external video signal when the outer edge of the character matches the color of the external video signal according to the brightness control signal of the video signal controller, and the output of the brightness adjuster and the video controller. And an image switcher for switching the image output of the image switcher according to the image switch signal of the image controller, wherein the video signal controller is a synchronization signal detected by the synchronization detector. The image display device according to claim 1, wherein the reading controller and the writing controller are controlled by a synchronizing signal of the video signal controller to display the characters by superimposing them on the background image. 3. The outer edge extender includes a first register for storing a row start value Is when a row address is I and a column address is J in a memory address for each character in the font ROM. , A second register for storing a row end value Ie, a third register for storing a column start value Js, a fourth register for storing a column end value Je, a row address I and the first register A first comparator for comparing the output of the second register, a second comparator for comparing the row address I with the output of the second register, and a second comparator for comparing the column address J with the output of the third register. 3 comparator, a fourth comparator for comparing the column address J with the output of the fourth register, and Is = with reference to the outputs of the first and second comparators.
Ib = Is-1 when I, Ib = Ie + when Ie = I
Js = by referring to the I-coordinate generator that outputs 1 and the outputs of the third and fourth comparators, respectively.
When J, Jb = Js-1, and when Je = J, Jb = Je +
With reference to the J-coordinate generator that outputs 1, and the outputs of the first to fourth comparators, Is = I,
When any one of Ie = I, Js = J, and Je = J is satisfied, a comprehensive edge determiner that determines the edge determination value output that is the outer edge data of the font ROM to be true, and an inner edge value of the character data is stored. A fifth register, a one-value detector that makes the one-value detection value true when the output of the fifth register and the pixel value of the character data have one value, and the one-value detector output and the total value 3. The image display device according to claim 1, further comprising a flag generator that sets an outer edge flag to be true when both outputs of the edge determiner are true.