JPS6385790A - Crt output circuit - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a CRT output circuit used in, for example, a hand-held display.

In head-up displays and the like, a hybrid scanning method is currently mainly used due to the demand for displaying a large amount of information on a CRT screen.

For example, if the type of information to be displayed has a shape such as a character, it is displayed using the stroke scanning method, whereas if the type of information is a complex shape such as a cloud, it is displayed using the raster scanning method. Furthermore, even in stroke scanning head-up displays, stroke symbols and a raster image projected on a portion of the screen are displayed simultaneously for the reasons described above.

However, in order to display raster images and stroke symbols on the screen, the CRT output circuit becomes complicated due to the difference in scanning methods. In other words, when displaying raster images,
Generally, a retrace circuit is required, and there is a problem in that, in the deflection signal, separate deflection amplifier circuits are required for displaying a raster image and displaying a stroke symbol.

The present invention was devised to solve the above-mentioned problems, and it is possible to display stroke symbols and raster images on the screen using the same deflection amplifier circuit, that is, to display raster images with a simple configuration. An object of the present invention is to provide a CRT output circuit capable of displaying images.

A CRT output circuit according to the present invention for reading a stroke outputs a stroke/raster switching signal related to time division, an XSY deflection voltage signal related to a stroke symbol and a raster image, and A symbol generator that outputs a stroke luminance signal when displaying a symbol, and outputs area information related to the screen display range when displaying a raster image, a video memory that records display data of the raster image, and a raster image. In connection with scanning the raster line in the opposite direction to the main transmission, there is an address counter that determines the address of the video memory from area information, and an analog conversion of the memory output signal read from the video memory and introduced to determine the raster brightness. A D/A converter that forms a signal, a luminance signal switching circuit that switches between a raster luminance signal and a stroke luminance signal based on a stroke/raster switching signal, and outputs the switched luminance signal, and an X and Y deflection voltage. The deflection amplifier circuit converts signals into currents and outputs XSY deflection signals.

Since the raster image is scanned in the opposite direction to the raster line, the X deflection signal can be a triangular wave, so the deflection amplifier that converts the X deflection signal is equipped with a retrace circuit. It is not necessary, and the Y deflection signal can be a ramp wave, but since its frequency is lower than the X deflection signal, there is no need to provide a retrace circuit in its deflection amplifier either.

Figure 1 is a configuration diagram of a CRT output circuit according to the present invention, Figure 2 (a) is a display diagram of a CRT screen showing a raster image and stroke symbols, and Figure 2 (b) is a diagram showing a CRT screen display. teeth,
It is a figure which shows raster scanning of the raster image of (a).

In FIG. 1, 10 is a CRT control circuit, 20 is a CRT control circuit, and 20 is a CRT control circuit.
The output circuit 30 is a CRT.

The CRT output circuit 30 according to the present invention includes a symbol generator 2
1, an address counter 22, a video memory 23,
It is composed of a D/A converter 24, a deflection amplifier circuit 25, and a stroke/raster switching circuit 26. By scanning the raster image 41 in the opposite direction to the raster line-main transmission, the deflection amplifier This is intended to simplify the configuration of the circuit 25. This CRT output circuit 20
As shown in FIG. 2(a), based on the command from the CRT control circuit 10, the CRT 30ii! This circuit displays a stroke symbol 40 and a raster image 41 on a part of the surface. Information for displaying the stroke symbol 40 of this command is outputted via the symbol generation 321, but information for displaying the raster image 41 is outputted mainly via the video memory 23.

The symbol generator 21 mainly plays the role of forming a deflection signal and a luminance signal necessary for displaying a stroke symbol 40 and a raster image 41 on the screen of the CRT 30. The signal output from this symbol generator 21 will be explained. Regarding the deflection signals, although there are differences in scanning methods, both of them use X and Y deflection voltage signals 213.
．． 214. In one luminance signal,
When the stroke symbol 40 is displayed, it is output as a stroke luminance signal 212, but when the raster image 41 is displayed, area information regarding the screen display range of the CRT 30 is output. This area information will be described later. Furthermore, each signal is output in time division during stroke display and raster display, and a stroke/raster switching signal 215 is output to the external circuit in order to operate in synchronization with this time division. That's what I do.

The video memory 23 is a video RAM that corresponds one-to-one with the screen of the CRT 30, and the display data 12 of the raster image 41 introduced from the CRT control circuit 10 is once recorded in this video memory 23, and the symbol generator Although not shown, this video memory 23 is read out in synchronization with the X and Y deflection voltage signals 213 and 214 output from 21 and output as a memory output signal 231. One of them performs writing and the other reads at the same time.In other words, the video RAM that has been read is the next video RAM that has been written.
By switching to AM and not repeating this, the display data 12 is output continuously.

The address counter 22 is an up/down counter that controls reading of the video memory 23, and determines the address of the video memory 23 based on the area information introduced from the symbol generator 21, and displays a raster image on a part of the screen. 41 is displayed. By the way, CR
When the image on T30 is displayed in coordinates on the X and Y axes, the screen display range of the raster image 41 is the range from t to x2 on the X axis (distance A), as shown in Fig. 2(a). ), and for the Y axis, the range from Y to Y2 (
This screen can also be considered as display data of the video memory 23. Therefore, the screen display range of the raster image 41 is as follows in the video memory 23:
It is determined by three data: the address (Xl, Yl) which is the starting point of the raster image 41, address space A on the X axis, and address space B on the Y axis.

This is used as area information. This address counter 2
2 performs a counting operation in synchronization with the above-mentioned X and Y deflection signals 251 and 252 to determine the address of the video memory 23. This counting operation and scanning of the raster image 41 will be described later.

The D/A converter 24 inputs the memory output signal 231 and converts it into analog to form a raster luminance signal 241.

The stroke/raster switching circuit 26 is a circuit that switches between the stroke luminance signal 212 introduced from the symbol generator 21 and the above-mentioned raster luminance signal 241, and sends the switched luminance signal 261 to the luminance circuit 32 of the CRT 30. This switching is performed using a stroke/raster switching signal 215.

The deflection amplifier circuit 25 is composed of, for example, a 5EEP negative feedback type B class amplifier, and is a circuit that performs voltage/current signal conversion.
It is composed of 5B. Each deflection amplifier circuit 25 is
X and Y deflection voltage signals 213 and 214 are respectively introduced to form X and Y deflection signals 251 and 252, which are CR
It is sent to the deflection yoke circuit 31 of T30.

Here, stroke symbol 40 and raster drawing @! The scanning method with 41 will be explained below. Stroke symbol 4
0 is displayed by conventional stroke scanning, but the raster image 41 is displayed by scanning the raster line in the opposite direction to the main line, as shown in FIG. 2(b). When displaying the image 41, the symbol generator 2
1 outputs an X and Y deflection voltage signal 21 to output a triangular wave X deflection signal 251 and a ramp wave Y deflection signal 252.
Outputs 3.214. That is, the CRT output circuit 20
In the deflection signal 251, the raster image 41 is scanned during the retrace period, and the address counter 22 that determines the address of the video memory 23 also performs a counting operation in synchronization based on the above scanning. It is carried out.

In this embodiment, a stroke scanning type CRT is used.
Although the output circuit has been explained, it is not limited to this.
A hybrid scanning method that also serves as a stroke scanning method can be similarly implemented. Furthermore, a CRT output circuit for color images instead of monochrome images can be expanded and implemented using the same concept.

The CRT output circuit according to the present invention can omit the retrace circuit in the deflection amplifier circuit as the raster image is scanned in reverse from the raster line to the main transmission. The configuration can be simplified. Furthermore, since the raster image is scanned quickly, it is possible to display a large amount of information on the CRT screen in terms of time.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a CRT output circuit according to the present invention, FIG. 2(a) is a display diagram of a 017 screen showing a raster image and stroke symbols, and FIG.
It is a figure which shows raster scanning of the raster image of (a). 20... CRT output circuit, 21... Symbol generator, 22... Address counter, 23... Video memory, 24... D/A converter, 25... Deflection amplifier circuit, 26...・・Stroke/raster switching circuit, 30・
...CRT. Patent applicant Shimadzu Corporation Representative Patent attorney Takaharu Ohnishi (a) Figure 2

Claims (1)

[Claims] (1) In a CRT output circuit that displays a stroke symbol and a raster image on a CRT screen in a time-division manner, a stroke/raster switching signal related to the time-division, an X related to the stroke symbol and the raster image, a symbol generator that outputs a Y deflection voltage signal and a stroke luminance signal when displaying the stroke symbol, and outputs area information related to the screen display range when displaying the raster image; a video memory that records display data of a raster image; and an address counter that determines an address of the video memory from the area information in connection with scanning the raster image in a reverse direction for each raster line; a D/A converter that converts into analog a memory output signal read from the video memory and introduced into it to form a raster luminance signal; and a D/A converter that converts the raster luminance signal and the stroke luminance signal based on the stroke/raster switching signal. A CRT output characterized by comprising: a brightness signal switching circuit that performs switching and outputs a switched brightness signal; and a deflection amplifier circuit that converts the X and Y deflection voltage signals into currents and outputs X and Y deflection signals. circuit.