JPS6046446B2 - Video display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses a light pen to detect optical signals from a CRT screen to determine the corresponding position, input data into memory, and read out the data in subsequent fields. The present invention relates to a video display device that displays arbitrary graphics on a CRT.

In such a video display device, in order to suppress fluctuations in the light pen indication position due to the difference between the initial light emission amount and the light emission amount after drawing an arbitrary figure, the light pen instruction obtained in the first field is A configuration is adopted in which the vicinity of the position is displayed at a constant brightness in the second field.

In such a configuration, if the initial image is dark, the raster detection signal by the light pen cannot be obtained in the first field, and therefore the position to be displayed at a constant brightness in the second field cannot be obtained. I had the inconvenience of not being able to specify it. The present invention has been made to solve these problems, and will be described in detail with reference to the drawings.

FIG. 1 shows the configuration of the video display device of the present invention, FIG. 2 is a waveform diagram for explaining the operation of the device, and FIG.
This is an enlarged view of section ``A'' in the figure. 1st
In the figure, a light signal on the screen of a CRT 1 is detected by a light pen 2, converted into an electrical signal, and input to an amplification circuit 8. The signal amplified by this amplification circuit 8 is converted into a binarization circuit J
The detection signal e is converted into a binary signal d by path 9 and input to the P-th pulse detection circuit 10 that detects the P-th pulse.
is obtained and inputted to the flip-flop 11 as a set input. This flip-flop 11 is reset by the trailing edge pulse VL of the vertical synchronizing signal V. Therefore, a flip-flop output f is obtained as the output of the flip-flop 11, which rises at the time of the detection signal e and falls in synchronization with the trailing edge pulse VL. The counting operation of the second counters 12 and 13 is stopped. still,
The first counter 12 counts the clock pulses φ, and the second counter 12 counts the clock pulses φ.
The counter 13 counts the Ohira synchronization signal H. Therefore, the counting operation of both counters 12 and 13 stops when the detection signal e is output, and the counters 12 and 13 at that time stop counting.
3 output corresponds to the instruction address of light pen 2. The outputs of the counters 12 and 13 are the latch circuits 14 and 1.
5, respectively, and the central pulse of the vertical synchronizing signal ■M
It is latched in synchronization with the logical product 16 of the output f of the flip-flop 11 and the output g of the flip-flop 11. Also, these latch circuits 1
The outputs of 4 and 15 are input to matching circuits 17 and 18, respectively, and the other inputs of these matching circuits 17 and 18 are counters 21 and 21 that indicate the address of the image memory 23, respectively.
22 outputs are used. Therefore, when the address for the indicated coordinates of the light pen detected in the first field matches the display address from which the image memory 23 should be read, match signals 1 and j are output from the match circuits 17 and 18. Section sampling circuit 19 depending on the coincidence signal 1,j
, 20 are triggered. In this way, the section sampling circuit 1
9 and 20 operate to obtain the sampling signals K and l, which are obtained from the T flip-flop 25 which is triggered by both signals K and l and the leading edge pulse ■H of the vertical synchronizing signal {circle around (2)}. 1st. The second field discrimination pulse C and the light pen switch signal SW are ANDed by an AND gate 24,
A logical output m is generated, and this logical output m passes through an OR gate 5 to become a logical product output n. is applied to the multiplexer 6 to control the operation of the multiplexer 6. on the other hand,
Image memory 2 addressed by counters 21 and 22
The output from CRT1 is sent via multiplexer 6 to D/A conversion circuit 21. It will be converted into an analog drive level and displayed on the CRTl screen, and during the period of the logic output m of the AND gate 24, a color corresponding to a separately designated color signal (DAT) will be displayed.

Note that the color corresponding to this color signal (DAT) is set to a brightness that can be detected by the light pen 1. In this way C
When the image is displayed on the RTl screen and the raster of the CRTl screen can be detected in the first field, or the raster is detected initially and as the image is constructed, the first field
This is effective when the raster cannot be detected in the field.

In other words, even if a raster cannot be detected in the middle of the first field, the latch circuits 14 and 15 will still detect the second raster immediately before it.
Since the address obtained in the field is stored, the next second field displays the color corresponding to the color signal (DAT) near the direction of the light pen 2.
It is possible to detect the raster at that location. At this time, an image is formed on the CRTl screen by sequentially rewriting the addresses corresponding to the light pen instruction addresses obtained in the second field as data in the image memory 23. However, with the above-described configuration, if the initial image on the CRTl screen is dark and a detection signal from the light pen 1 cannot be obtained, raster cannot be detected and normal operation cannot be performed.

In the present invention, such problems are solved by the timer circuit 3.
This problem is solved by adding a section sampling circuit 4. That is, the timer circuit 3 operates depending on the light pen switch signal SW, and the timer circuit 3 is set to output the light pen switch signal SW with a delay longer than the vertical display period after inputting the light pen switch signal SW. Further, it is configured to be reset by the detection output e of the P-th pulse detection circuit 10. Therefore, if the raster is not detected in the middle of the operation, the output a of the timer circuit 3 will not become "1", but if the light pen switch signal SW turns 0N, the output will continue for an arbitrarily set time of two or more vertical periods. rear,
"゛1" and drives the next section sampling circuit 4 to obtain one field sampling signal b.This sampling signal b passes through the OR gate 5 and becomes the logical sum output n, and the multiplexer 6
is controlled to display a signal corresponding to the color signal (DAT) on the CRTl screen for one field period. Therefore, at that time, the light pen 2 detects the raster, and it becomes possible to set an address corresponding to the specified position. After that, the image is gradually constructed by repeating the normal operations as described above. As is clear from the above description, the present invention includes a timer circuit that is triggered by a light pen operation signal, and forcibly brightens the CRT screen when the timer circuit operates, so that the initial state of the displayed image Even when it is dark, the indicated position can be detected using a light pen, which brings about a great effect on an image processing device using a CRT and a light pen.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the internal configuration of the device of the present invention, and FIG.
The figure is a waveform diagram for explaining the operation of the device, and FIG. 3 is a waveform diagram showing the main parts enlarged.
2 and 13 are counters, 14 and 15 are latch circuits, 17,
Reference numeral 18 indicates a matching circuit, and reference numeral 23 indicates an image memory.

Claims (1)

[Claims] 1 A video that displays arbitrary figures on the CRT by detecting optical signals from the CRT screen using a light pen, determining the corresponding position, inputting data into the image memory, and reading out the data in subsequent fields. In the display device, a CRT, a light pen that detects an optical signal from the CRT screen, a first address means that determines an address to indicate to the light pen, and a second address means that indicates an address of an image memory. , means for detecting a coincidence between both of these address means, and a multiplexer for selecting the contents of the image memory and the color signal based on the coincidence signal from the detection means and applying one of them to the CRT. and a timer circuit triggered by the operation signal of the light pen, and the first address means uses the light pen instruction address obtained in the previous display field as a determined address, and the timer circuit A video display device that forcibly brightens the CRT screen during operation to enable raster detection.