JPH0572592B2 - - Google Patents

Description

[Detailed description of the invention] (Technical field) The present invention relates to an image display device.

(Prior Art) A conventional image display device of this type is as shown in FIG.
The row dot data of the character corresponding to the character code is input to the character generator 2 as the character address data of the character generator 2, and the row dot data of the character corresponding to the character code is input to the character generator 2 as the row code signal of the character generator 2.
It is designed to be sequentially output as parallel data for each row in synchronization with LA0 to LA1, and this output parallel data is converted by the column clock in the shift register 3 to form a video signal and stored in the refresh memory. Codes for multiple characters stored in 1 were displayed sequentially as characters on the CRT4.

FIG. 2A shows an example of a character image displayed as matrix dots with 8 rows and 5 columns, and FIG. 2B shows row code signals corresponding to each column.
The character code outputs "2",
For example, if LA2 to LA0 are in the state of (001), the parallel data in the second row becomes (01110) and is read into the shift register 3 and becomes a video signal in synchronization with the column clock as shown in Figure 2. The second, third, and fourth dots light up as shown by diagonal lines.

By the way, conventionally, in order to increase the display size, a method has been used in which the cycle of the row code signal and column clock is doubled, for example, when increasing the cycle of the row code signal and column clock from 1x the character size to 2x the character size. Ta. In such a method, even if the display request signal is issued at the same position in the horizontal direction, the character dimensions differ, so in the case of a character with double the character size, the second dot of the row dot data of the character with the character size once Similarly, in the case of a character whose character size is 3 times, it will be displayed from the 3rd dot position of the row dot data of a character whose character size is 1 times, and the larger the character size, the greater the deviation. When the character dimensions are changed by many digits in the vertical direction and displayed, it is visually very unsightly.

(Objective of the Invention) An object of the present invention has been made in view of the above points, and is to provide an image display device that can be enlarged on a display screen in a natural manner even if character dimensions are changed.

(Structure of the Invention) According to the present invention, the column clock when converting parallel data output from the character generator into serial data after the display request signal is output is
An image display device is obtained in which the first pulse outputs a column clock with the same period as in the case where the character size is 1 times, and the column clocks after the second pulse output column clocks with a period corresponding to the character size.

FIG. 3 shows the configuration of an embodiment of the present invention. As the display position detection counter 11 sequentially counts up, it is compared with the data in the display address memory 9 by a matching circuit 10, and at the same time when they match, a display request signal is output. The programmable divider 6 detects the display request signal and outputs a row code signal according to the row direction display size memory 5. Similarly, the programmable divider 8 detects the display request signal and outputs the column clock, but the first pulse is the character size 1.
Outputs the column clock with the same period as in the double case, and
After the pulse, a column clock having a period corresponding to the character dimension indicated by the column direction display dimension memory 7 is output.

Refresh memory 1 consists of RAM,
It is designed to memorize the codes of multiple characters displayed on the CRT4. The character generator 2 stores character pattern data composed of matrix dots. The address of this character generator 2 is the output of the refresh memory 1 and the programmable divider 6.
The line code signal output from is input,
Parallel data for each row is sequentially output from the character generator 2 in accordance with the row code signal. Parallel data is transferred to shift register 3 before the column clock arrives.
The data is taken into the CRT 4, converted into serial data in synchronization with the column clock, and supplied to the CRT 4 as a video signal.

As is clear from the above explanation, the first pulse of the column clock when the parallel data output from the character generator 2 is taken into the shift register 3 and converted into serial data after the display request signal is output is the character generator 2. A CRT 4 with different display dimensions is output by outputting a column clock with the same cycle as in the case of 1 times the dimension, and from the second pulse onwards, outputting a column clock with a cycle corresponding to the character dimension indicated by the column direction display dimension memory 7. Even when the upper character is displayed in multiple digits in the vertical direction, it is possible to perform an enlarged display with the display positions aligned, and this has the effect of making it visually very easy to see with a simple configuration.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional image display device. 2A and 2B are diagrams showing character image columns and row code signals corresponding to each column to explain the operation of FIG. 1. FIG. 3 is a block diagram showing one embodiment of the present invention. 1... Refresh memory, 2... Character generator, 3... Shift register, 4...
Braun tube, 5... Row direction display dimension memory, 6...
...Programmable divider in row direction, 7...Display dimension memory in column direction, 8...Programmable divider in column direction, 9...Display address memory, 1
0... Matching circuit, 11... Display position detection counter.

Claims (1)

[Claims] 1. Input at least a refresh memory, a row code signal generated from data indicating a row direction display dimension stored in a row direction display dimension memory, and an output character code signal output from the refresh memory. an image display device comprising: a character memory; a shift register to which a row dot data signal and a column clock outputted from the character memory are input; and the display element which inputs and displays the output of the shift register; The column clock is output from a programmable divider that inputs the minimum column clock and the size signal output from the column direction display dimension memory, and the programmable divider inputs the minimum column clock and the size signal output from the column direction display dimension memory. If the character dimension of the character to be displayed on the screen is not the minimum display dimension, the character dimension is the minimum display dimension for the first pulse of the column clock. The column clock with the same cycle as in the case of , is output in synchronization with the display request signal,
An image display device characterized by having means for outputting a column clock having a period obtained by variably dividing the minimum column clock according to the character size indicated by the size signal given from the column direction display size memory from the second pulse onward. .