JPH0313793Y2 - - Google Patents

Description

[Detailed description of the invention] A. Industrial application field This invention is a video display device using a CRT or a light pen, and in particular, has an image memory, and the image memory is stored in accordance with the signal output from the light pen facing the CRT. Write image data to and write the image data to
It relates to a video display device that outputs and displays on a CRT.

B. Prior Art Figure 1 shows the configuration of an existing CRT-based video display device. In the figure, 1 is a synchronization signal generation circuit, 2 is a CRT, 3 is an address counter, 4 is an image memory, 5 is a light pen, 6 is a latch circuit, and 7
8 is a D/A conversion circuit, and 8 is a write data control circuit.

In such a configuration, the clock φc is input to the synchronization signal generation circuit 1, and the synchronization signal generation circuit 1 outputs a horizontal synchronization signal H and a vertical synchronization signal V, respectively.
The horizontal synchronizing signal H and vertical synchronizing signal drive the CRT2.

The clock φc is input to the address counter 3 and outputs an address signal for the image memory 4.
The address signal is the one indicated by the light pen 5.
It is also input to the latch circuit 6 to detect the address corresponding to the coordinates of the CRT screen. The data outputted from the image memory 4 is input to the D/A conversion circuit 7 and displayed on the screen of the CRT 2 as an analog signal.

The light pen 5 outputs a bright line detection signal 1 and a light pen switch signal SW ₁ that turns ON when the light pen presses the screen of the CRT 2, thereby causing the latch circuit 6 to latch the output of the address counter 3. Therefore, the output of the address counter 3 latched by the latch circuit 6 corresponds to the coordinate position of the CRT 2 indicated by the light pen 5.
The image data is input to the write data control circuit 8 and the image data in the image memory 4 at that address position is rewritten. Here, the write data control circuit 8 generally employs a microcomputer system using a microprocessor as the CPU.

With the above configuration, you can freely use the light pen 5.
You can draw figures and characters on the CRT2 screen.

Such a conventional configuration is known, for example, from Sanyo Electric Technical Report,
Vol.13, No.1.Feb1981, P11-14 for details.

However, according to this structure, when drawing a figure or character, it immediately becomes the final image. Therefore, for example, just like when drawing a picture on regular drawing paper, first draw the sketch, outline, etc. lightly with a pencil, then draw the final lines with ink, etc., and then erase the previous sketch with poppy rubber to finish the drawing. It is not possible to complete the task. In other words, with this configuration, it is not possible to draw a sketch, so it takes a lot of effort to make corrections before the picture is completed.

C. Purpose of the invention The purpose of the invention is to make it possible to draw sketches and sketches even in the above-mentioned video display device, and to improve its operability and work efficiency.

D. Structure of the invention The present invention includes a figure brightness switching means that allocates a plurality of bits to each pixel as an image memory, specifies the brightness of the figure drawn as a result by the light pen 5, and zero bits for low-brightness figures. A low-brightness figure erasing instructing means is provided to instruct the user to erase the low-brightness figure, and when the figure drawn in low-brightness is used as a sketch or underdrawing, and the final completed screen is later drawn in high-brightness, the figure corresponding to the low-brightness figure can be erased. It has a configuration that erases the sketch and the bottom drawing by setting the bit in the drawing to 0.

E. Embodiment FIG. 2 shows the configuration of the video display device of the present invention. In the same figure, 1 to 8 are a synchronization signal generation circuit and a write data control circuit, respectively, as in FIG. 1, and the difference from FIG. 1 is a write data control circuit 8.
The brightness change switch 9, the erase switch 10 shown below and the high brightness figure erase switch 11 are associated with each other, and a plurality of bits are assigned to each pixel of the image memory 4.

The brightness changeover switch 9 corresponds to the above-mentioned figure brightness changeover means, and when the brightness changeover switch 9 is on the A side, the figure drawn with the light pen 5 is displayed with low brightness, and conversely, when the brightness changeover switch 9 is on the B side, the figure drawn with the light pen 5 is displayed with low brightness. When set, the configuration is such that figures drawn with the light pen 5 are displayed with high brightness. For simplicity, each pixel in the image memory 4 has 2 bits (lower _b0 , upper
b ₁ ) is assigned. When the brightness selector switch 9 is on the A side, image data is written into the image memory 4 using only _b0 of these two bits. Low brightness mode (sketch mode) and high brightness mode (final drawing mode) will be explained.

Low brightness mode Of the two bits assigned to each pixel in the image memory 4, no operation is performed on _b1 , and image data is written using only _b0 . Therefore, if a figure is drawn in this low brightness mode, the low brightness figure will be displayed on the CRT2. This figure is used as a sketch for the final image described below.

High Brightness Mode Of the 2 bits allocated to each pixel in the image memory 4, no operation is performed on _b0 , and image data is written into the image memory 4 using _b1 .

The erase switch 10 shown in the lower figure corresponds to the above-mentioned low-brightness figure erasing means, and is configured to erase the image data written in b0 in the low-brightness mode by closing the erase switch ₁₀ shown in the lower figure.

The high-intensity figure erasing switch 11 is an instruction means for erasing the image data written in _b1 in the high-intensity mode. The brightness changeover switch 9, the erase switch 10 shown below, and the high brightness figure erase switch 11 are instruction means for the write data control circuit 8. The write data control circuit 8 performs each operation on the image memory 4 described above. Since the write data control circuit 8 can be easily realized with a microcomputer or a random logic circuit,
I will omit the explanation here.

Assuming that the write data control circuit 8 is constituted by a microcomputer, the brightness change switch 9, the erase switch 10 shown below, and the high brightness figure erase switch 11 are connected to the I/O port 113 of the microcomputer 12 as shown in FIG. It is monitored by the CPU 15 in accordance with the system program stored in the ROM 14 of the connected microcomputer 12. I/O port 216 has latch circuit 6.
The output of is entered. Further, the address and data buses are connected to the address and data terminals of the image memory 4.

According to the above configuration, it is possible to first draw a faint sketch in the low-brightness mode, and then draw the final figure picture in the high-brightness mode with reference to the sketch. For high-intensity figures and low-intensity figures, the high-intensity figure erase switch 11 and the sketch erase switch 10 can be closed, respectively, so when the writing of the final figure is completed, only the sketch needs to be erased.

By adjusting the D/A converter 7 so that it is saturated with the "1" input of _b1 , it is possible to eliminate the unnaturalness in which the brightness increases in the portion where the sketch and the final image overlap.

F. Effects of the Invention As is clear from the above, according to the present invention, by selectively using each pixel in the image memory, it is possible to easily input a figure using a sketch or a bottom drawing, which has a great practical effect.

[Brief explanation of the drawing]

Figure 1 is a block diagram showing the configuration of a conventional video display device using a light pen, Figure 2 is a block diagram showing the configuration of the video display device of the present invention, and Figure 3 is a diagram showing the configuration of the main parts of the device of the present invention. In the block diagram shown, 2 is a CRT, 4 is an image memory, 8 is a write data control circuit, 9 is a brightness changeover switch, and 10 is an erase switch shown below.

Claims (1)

[Claim for Utility Model Registration] By detecting bright lines from a CRT screen using a light pen, determining the relevant position, inputting data into the image memory, and reading out this data.
In a video display device that displays arbitrary figures on a CRT screen, an image memory in which multiple bits are assigned to each pixel for low-brightness display and high-brightness display, and digital data in the image memory are D/A converted. and a D/A conversion means for applying voltage to a CRT, a figure brightness switching means, and a low-brightness figure erasing instruction means, and when the figure brightness switching means changes the figure display state to a low-brightness display state, When a low-brightness figure is displayed on a CRT using the low-brightness display bit of the image memory and a high-brightness display state is made by the figure brightness switching means, the image memory in the low-brightness display state is The low-brightness display bit data of the image memory is left as is, and the high-brightness display bit of the image memory is used to display high-brightness figures on the CRT, and if necessary, the low-brightness figure deletion instruction means is used to display high-brightness figures. A video display device characterized in that a bit for low brightness display in the image memory is erased.