JPS6322589B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a raster scan type cathode ray tube display device, and more particularly to a display device that can display two or more pieces of screen information in a superimposed manner on the same display surface.

For example, when displaying figures and characters superimposed on the same display surface, the character codes are read out sequentially from the first memory that stores the character codes, each character code is converted into a character pattern, and each character is horizontally synchronized. Dots are sequentially displayed on the horizontal scanning line with the signal as the base point. The horizontal synchronizing signal is generally created based on a counter that reads character codes from the first memory, and an integer number of characters are arranged and displayed on one horizontal scanning line.

On the other hand, if, for example, graphic information to be superimposed on the character display is stored in the second memory in units of a number of dots different from the number of dots in the horizontal direction of one character, the graphic information is superimposed on one horizontal scanning line. The number of graphical units drawn is not necessarily an integer. Therefore,
Even if the graphic information is read out from the second memory at an appropriate count period, it may not be possible to properly superimpose the information because it cannot be made to match one horizontal synchronizing signal period and the image flows. Successful synchronization can be achieved by configuring the second memory to have just an integer number of storage units between horizontal synchronization signal periods, but this is a major constraint on the memory configuration for graphic information. Furthermore, when an integer number of graphic information is arranged within a horizontal synchronization signal period, the horizontal display period is not necessarily an integral multiple of the graphic information, resulting in the disadvantage that part of the displayed graphic may be deleted. Therefore, the conventional device described above has a drawback in that it is extremely difficult to superimpose a character display in units of an arbitrary number of dots and a graphic display in units of an arbitrary number of dots.

The purpose of the present invention is to solve the above-mentioned conventional drawbacks and
Character information, graphic information, etc. stored in the first memory and the second memory, each consisting of an arbitrary number of dots, are read out from the other memory within one cycle of the horizontal synchronization signal based on the readout count number of one. An object of the present invention is to provide a cathode ray tube display device that can synchronize and display graphic information and the like stored in the computer.

The display device of the present invention includes a character display system that reads character information, etc. stored in a first memory at a constant period and displays it on the display device, and a character display system that reads character information, etc. stored in a second memory at a different period from the above. In the raster scan type cathode ray tube display device, the graphic display system is provided with a graphic display system that reads out the information and displays it in a superimposed manner on the display device, wherein the graphic display system is provided with means for varying the readout period after a certain number of information readouts. It is characterized by

Next, the present invention will be explained in detail with reference to the drawings.

The figure is a block diagram showing one embodiment of the present invention. This embodiment is a character display system A that displays one character in units of dot display of 9 pixels in the horizontal direction.
and a graphic display system B that displays graphics in units of dot display for 16 pixels.
An example will be described in which a character display and a graphic display are displayed in a superimposed manner on the same cathode ray tube display section 7 by the output of.

The character display system A includes an oscillator 1 that outputs a pulse signal every display time t _p of one pixel (one dot) on the display section 7, a frequency divider 2 that divides the output pulse of the oscillator 1 by nine, and a frequency divider 2 that divides the output pulse of the oscillator 1 by nine. A counter 3 that counts the output pulses of the frequency generator 2 and sends the count value as an address signal to the memory 4, and outputs a horizontal synchronization signal when the number of input pulses is an integral multiple of 9 after full counting, and A first memory 4 that stores character codes, a character pattern conversion circuit 5 that converts the character code output from the first memory 4 into a dot pattern, and a video signal that converts the dot pattern output from the character pattern conversion circuit 5 into a video signal. The count value of the counter 3 is updated every nine output pulses of the oscillator 1, and the character code is sequentially read from the first memory 4 and is converted and output by the character pattern conversion circuit 5. The data is converted into a dot pattern, converted into a video signal by the video circuit 6, and displayed as characters on the display section 7. Horizontal scanning of the display section 7 is performed in synchronization with a horizontal synchronization signal output from the counter 3. The above is the same as the conventional display device.

On the other hand, the graphic display system B stores graphic information in units of 16 dots in the second memory 10, and the graphic information stored in the address position specified by the output of the counter 9 is stored in the second memory 10. Each output is sequentially read out, converted into a video signal by the video circuit 11, and superimposed on the output signal of the video circuit 6.
The counter 9 counts the output pulses of the divided period 8 and outputs the count value as an address signal for the second memory 10. On the other hand, the counter 12 operates in synchronization with the output of the counter 9, and outputs an output signal when it counts 54, for example, to change the frequency division ratio of the frequency divider 8 to, for example, 1/18. Frequency divider 8 is a circuit that normally divides the output pulse of oscillator 1 by 1/16, but
This is a frequency divider whose frequency is changed to 1/18 based on the output signal of the counter 12. In this embodiment, the frequency divider 8
The counter 12 constitutes "means for varying the read cycle after a certain number of information reads."

Now, the count period of counter 3 of character display system A
N ₁ t _p is 9t _p , and if the count number N _H1 in one horizontal synchronization signal period T _H is 106, and if one dot display time t _p is 33 nanoseconds, one horizontal synchronization signal period T _H is 31.482 microseconds. Of course, this includes the horizontal blanking time, so the number of displayed characters is less than 106. Then, from the second memory 10, one unit of figure is read out every 16 pulses, so 54 units of figure are displayed in 28.512 microseconds, and then the readout period is changed, so that 5 times of every 18 pulses, or A figure of 5 units is read out in 2.970 microseconds. By making this period shorter than the horizontal blanking time unrelated to display, the total time can be reduced to 31.482 microseconds without displaying this portion on the display screen. That is, it is possible to synchronize with the horizontal synchronization signal every 31.482 microseconds output from the counter 3 of the character display system A.

Generally speaking, the display time of one dot on the display section is t _p , the count period of each character is N ₁ t _p , the number of characters counted within one horizontal synchronization signal period is N _H1 , and the other, for example, the count of graphic information When the period is N ₂ t _p and the number of graphic information read is N _H2 , the horizontal synchronizing signal T _H is as follows: T _H = N ₁ t _p ×N _H1 = N ₂ t _p × N _H2 ……(1) Otherwise, synchronization will not be achieved, but in the present invention, the above equation (1) is changed to obtain T _H = N ₁ t _p ×N _H1 = N ₂ t _p × (N _H2 − N _MH2 ) + N _M2 Synchronization is achieved by setting t _p ×N _MH2 ……(2). however,
N _MH2 is the number of counts in the horizontal synchronization signal.
This is a count number in which the reading period of unit information is a period N _M2 t _p that is different from the normal N ₂ t _p , and N _MH2 and N _M2 are appropriately selected so as to satisfy equation (2). However, N _M2 ×N _MH2 ×t _p is selected to be smaller than the horizontal blanking time. In the above example, N _M2 = 18 and N _MH2 = 5 were selected, so N _M2 ×
N _MH2 ×t _p =2.970 microseconds. In other words, the readout period from the second memory is N ₂ t _p up to a certain number (N _H2 −N _MH2 ),
Thereafter, the cycle was changed to N _M2 t _p within the horizontal blanking time, and by adding five cycles of this cycle to the previous illustrated display time, it became possible to match the horizontal synchronizing signal cycle T _H. in general,
Even if the reading cycles of unit information in the first memory and the second memory are arbitrarily independent, it is possible to determine N _MH2 and N _M2 that satisfy equation (2), and the constraints only that N _MH2 ×N _M2 ×t _p is less than the horizontal blanking time. It is possible to eliminate the conventional drawback that the two systems cannot be displayed synchronously with respect to arbitrary reading cycles due to the constraint of equation (1). Therefore,
It is easy to display the output signals of two systems, which display arbitrary dot numbers as units, by superimposing the output signals of the other system on the same display in accordance with the horizontal synchronization signal determined by one system. It has the effect of making it possible.

[Brief explanation of the drawing]

The figure is a block diagram showing one embodiment of the present invention. In the figure, 1... oscillator, 2, 8... period division, 3, 9... counter, 4... first memory,
5...Character pattern conversion circuit, 6, 11...Video circuit, 7...Display section, 12...Counter, 10
...second memory, A...character display system, B...graphic display system.

Claims (1)

[Claims] 1 A character display system that reads character information, etc. stored in a first memory at a constant cycle and displays it on a display device, and a character display system that reads graphic information, etc. stored in a second memory at a different cycle from the above and displays it on the display device. A raster scan type cathode ray tube display device comprising a graphic display system for superimposing and displaying information on a cathode ray tube display device, wherein the graphic display system is provided with means for varying a readout period after a certain number of information readouts. Tube display.