JPH0121512B2 - - Google Patents

Description

[Detailed Description of the Invention] This invention provides a method for displaying images on a CRT screen on which images are displayed based on video signals conforming to the NTSC standard.
The present invention relates to a display device that can superimpose display information such as characters in an extremely easy-to-see manner.

For example, display information such as characters supplied from an external electronic device is superimposed using a dot matrix on the display screen of a normal television receiver, which displays images based on video signals that comply with the NTSC standard. A display device is known in which the display device is paused so that an image and display information such as characters can be displayed simultaneously. By the way, superimposition performed in such display devices is performed by superimposing a first video signal conforming to the NTSC standard for displaying images and a second video signal for displaying characters, etc. Therefore, if the brightness or color of the image where the text is superimposed is stronger than the brightness or color of the superimposed text, the text may be absorbed into the image. There was a problem that the image became very difficult to see or could not be seen at all.

This invention was made in view of the above-mentioned circumstances, and its purpose is to display information such as characters at any position on the display screen on which an image is displayed based on a video signal conforming to the NTSC standard. An object of the present invention is to provide a display device that can superimpose images in an extremely easy-to-see manner. The display device according to the present invention includes display information such as characters to be superimposed, and information (hereinafter referred to as
This information is called window information) is stored in correspondence with the dot matrix allocated on the display screen, and both of these pieces of information are read out sequentially as the display screen is scanned, and at this time the window information If the first video signal is specified to be cut off, the first video signal is cut off, the corresponding dot matrix is set to a state where the video is missing, that is, a window, and the above-mentioned data stored in this window is The display information is displayed using only the second video signal based on the display information.

Hereinafter, this invention will be described as a display device that superimposes color characters (color characters such as alphanumeric characters, numbers, and katakana) using a matrix of 8×8 dots on an image based on a video signal conforming to the NTSC standard. An explanation will be given based on an example.

FIG. 1 is a diagram showing a CRT display screen 1 in this embodiment. This display screen 1 displays an image based on a first video signal conforming to the NTSC standard, and
This is for displaying color characters using a dot matrix of ×8 dots, respectively, and the display screen ₁ has a dot matrix of 8×8 dots,
M ₂ ,... are assigned 64 horizontally for 32 rows, a total of 2048. Next, FIG. 2 is a diagram showing the format of display control information used in this embodiment. In this figure, display control information 2 is
16 consisting of the first byte 3 and the second byte 4
This is bit information, and an 8-bit character code 5 for specifying the type of character to be superimposed is set in the first byte 3. Also, the first bit _B1 of the second byte 4 has the following:
A window bit 6 is set which specifies whether or not the first video signal is cut off when the corresponding dot matrix is being scanned (ie, specifies whether the corresponding dot matrix is to be windowed). When the value of this window bit 6 is "1", the first video signal is cut off and the corresponding dot matrix becomes a window, and when the value is "0", the video and color characters are displayed simultaneously on the corresponding dot matrix. Specify to obtain. Further, the other bits of this second byte 4 include 3 for specifying the color of the character specified by the character code 5 (hereinafter referred to as the front color).
A bit front color code 7, a 3-bit back color code 8 for specifying the background color of the character (hereinafter referred to as the back color) on the dot matrix in which this character is displayed;
At a value of "1", inversion bits 9 are set to specify that the front color and back color are to be exchanged.

Next, FIG. 3 is a block diagram showing the configuration of this embodiment. In this figure, 10 indicates that the character code 5 corresponds to the dot matrix M ₁ to _{M 2048}
This is a character code memory stored in correspondence with each other, and is made up of, for example, a random access memory (hereinafter abbreviated as RAM) having a storage capacity of (8×2048) dots. 11 is a front color code memory in which the front color codes 7 are stored in correspondence with dot matrices M ₁ to M ₂₀₄₈ , respectively;
12 is a back color code memory in which the back color code 8 is stored in correspondence with each of the dot matrices M ₁ to M ₂₀₄₈ ; 13 is the inversion bit 9;
are inversion bit memories stored corresponding to dot matrices M ₁ to _{M 2048} , respectively. The front color code memory 11, the back color code memory 12, the inversion bit memory 13, and the character code memory 10 constitute a display information memory 14 in the present invention. 15
If the window bit 6 is a dot matrix
M ₁ to M ₂₀₄₈ are stored in correspondence with each other (1×
2048) A window bit memory with a storage capacity of 15 bits.
is the window information memory 16 in this invention.
becomes. Note that this window bit memory 15
and the front color code memory 11, back color code memory 12, and inversion bit memory 1.
3 is composed of a RAM having a storage capacity of, for example, (8×2048) bits. Next, 17 is a central processing unit (hereinafter abbreviated as CPU) such as a microprocessor, and 18 is this CPU 17, the character code memory 10, a front color code memory 11, a back color code memory 12, and an inversion bit memory 13. , a signal bus for connecting the window bit memory 15, etc., and 19 for connecting external electronic equipment (for example, a host computer), etc.
This is an I/O boat provided for exchanging signals with the CPU 17. And in this case,
Display information indicating the type or color of characters to be superimposed on the display screen 1 and a window indicating the position, size, etc. of a window for displaying the same characters is sent from the above-mentioned electronic device to the I/O boat 19. When information etc. are supplied, the CPU 17 reads these display information, window information, etc., and based on these information, displays the display control information 2.
is created for each character to be displayed, and these display control information 2 are used to store the characters in the character code memory 10, front color code memory 11, back color code memory 12, inversion bit memory 13, and window bit memory 15. Each is written to the address corresponding to the dot matrix to be displayed. Next, 20 is synchronized with the timing of scanning of the display screen 1 performed on the display section (to be described later) (that is, synchronized with the display timing of the dot matrix on the display screen 1).
Character code memory 10, front color code memory 11, back color code memory 1
2. A display control unit that sequentially reads out the stored contents from each of the inversion bit memory 13 and window bit memory 15. Further, 21 converts the character code 5 sequentially read out from the character code memory 10 into a dot matrix dot signal (a combination of "1" signal and "0" signal) for displaying characters corresponding to the character code 5. 22 is a shift register which receives the dot signals output from the character generator 21 in parallel and outputs them in series. 2
3 is an exclusive OR circuit, and one input terminal of this exclusive OR circuit 23 is connected to a shift register 2.
The dot signal outputted by the inverter 2 is supplied, and the inverting bit memory 9 read out from the inverting bit memory 13 is supplied to the other input terminal. 24 is a selector, and when the selector 24 is supplied with a "1" signal from the exclusive OR circuit 23,
The front color code 7 supplied from the front color code memory 11 is selected and output, while if a "0" signal is supplied from the exclusive OR circuit 23, the back color code 7 supplied from the back color code memory 12 is selected and output. It is configured to select and output color code 8. Therefore, if the inversion bit 9 is "0", the selector 24 outputs the front color code 7 for a "1" dot signal, and for a "0" dot signal, the front color code 7 is output. Back color code 8 is now output, and on the other hand, if inversion bit 9 is “1”,
A back color code 8 is output for a dot signal of "1", and a front color code 7 is output for a dot signal of "0". Next, 25 is a display section similar to, for example, a normal color television receiver, which displays images or dot matrix characters by scanning the display screen 1. This display section 2
5 is a first video signal conforming to the NTSC standard if the window bit 6 read from the window bit memory 15 is a "0" signal.
A signal (second
Display is performed using both the video signal of
On the other hand, if the window bit 6 is a "1" signal, the first video signal is cut off and display is performed using only the second video signal output from the selector 24.

Next, the operation of this display device having the above configuration will be explained. In order to simplify the explanation, in the following explanation, the dot matrix M ₆₉ to
Set the three dot matrices of M ₇₁ as window W, and write the characters "A, B," on this window W with the front color red and the back color blue.
The case where "C" is displayed is shown. First, the above-mentioned electronic device provides display information that specifies the letters "A, B, C", front color red, and back color blue, respectively, and window information that specifies the position and size of the window W. supply. In this case, the window information is, for example, a dot matrix M1 to _M1 on the display screen 1.
By using rows X ₁ to X ₃₂ and columns Y ₁ to Y ₆₄ of M ₂₀₄₈ , it can be done as (X ₂ , Y ₅ , X ₂ , Y ₇ ). next,
The CPU 17 reads this information via the I/O boat 19 and creates display control information 2 for each character "A, B, C". In this case, in each display control information 2, codes specifying the characters A, B, and B are set as the character code 5, "1" is set as the window bit 6, and "1" is set as the front color code 7. A code specifying red is set for each of the back color codes 8, a code specifying blue is set for each of the back color codes 8, and “0” is set for the inversion bit 9.Next, these three display control information 2 teeth,
Character code memory 10, front color code memory 11, back color code memory 1
2. They are written to addresses 69 to 71 in each of the inversion bit memory 13 and window bit memory 15, respectively. On the other hand, in the display section 25, the display screen 1 is being scanned, and in synchronization with this scanning, the character code memory 10, the front color code memory 11, the back color code memory 12, the reversing bit memory 13, and the window bit are being scanned. The contents of each address of the memory 15 are read out sequentially. Here, until the three pieces of display control information 2 are written into each of the memories 10 to 13 and 15, the contents of each address in the window bit memory 15 are all "0", and the contents of each address in the character code memory 10 are all "0". If the contents of the address were all character codes specifying non-display, an image would be displayed on the display screen 1 using only the first video signal VIDEO. Now, when the scanning of the display screen 1 progresses and this scanning reaches the position of the window W, the aforementioned display control information 2 is transferred from each of the memories 10 to 13 and 15 to the scanned dot matrix _M69 to _M71 . They are read out sequentially according to the following. Therefore, while the portion corresponding to window W is being scanned, the first video signal VIDEO
is cut off, and the second
The characters "A, B, C" are displayed using the front color red and the back color blue only by the video signal of . In this case, the front color red and back color blue of these superimposed characters "A, B, C" are completely unaffected by the first video signal VIDEO (i.e., unlike the conventional video brightness and It is extremely easy to see (because the colors are not absorbed into the image).

In this embodiment, the display information to be superimposed on the video is colored characters using a dot matrix of (8 x 8) dots, but in the display device according to the present invention, the display information is displayed in monochrome characters. It can also be used as letters, etc.
Furthermore, the display information is not limited to a dot matrix of 8×8 dots, but may be displayed using a dot matrix of any number of dots.

As is clear from the above description, the display device according to the present invention includes a display information memory that stores display information such as characters in correspondence with a dot matrix on a display screen, and a first video symbol conforming to the NTSC standard. A window information memory that stores information specifying whether or not to block the dot matrix in correspondence with the dot matrix, a display control unit that sequentially reads out the contents of these memories in accordance with scanning of the display screen, and a display unit are provided. , in this display section,
Based on the readout output of the window information memory,
I want to cut off the first video signal and display using only the second video signal, so
It is possible to set a window of any size and shape in which the image is cut out at any position on the display screen where the image is displayed based on the video signal according to the NTSC standard, and to display text etc. in this window. Display information can be displayed. Therefore, according to the present invention, it is possible to freely superimpose display information such as characters, which are extremely easy to read, in any position and in any amount on the display screen on which the video is projected, without being affected by the brightness or color of the video. Can be imposed.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the arrangement of dot matrix on the display screen of a display device according to an embodiment of the present invention, FIG. 2 is a diagram showing the format of display control information used in the embodiment, and FIG.
The figure is a block diagram showing the configuration of the same embodiment. 1...Display screen, 14...Display information memory, 1
6... Window information memory, 17... Central processing unit (CPU), 20... Display control unit, 21... Character generator, 22... Shift register, 24... Selector, 25... Display unit, M ₁ ～
M ₂₀₄₈ ...Dot matrix.

Claims (1)

[Claims] 1. A display information memory that stores display information to be displayed using a dot matrix in correspondence with each dot matrix allocated on a display screen;
A window information memory stores information specifying whether or not to cut off a first video signal conforming to the NTSC standard in correspondence with the dot matrix, and the display information memory and the window information memory store the stored contents on the display screen. a display control unit that sequentially reads out each window information in synchronization with the scanning of the window information memory;
a display unit that blocks the first video signal to form a window on the display screen, and displays in this window using only the second video signal generated from the readout output of the display information memory. A display device characterized by: