JPS6046445B2 - 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, the light obtained in the first field is A configuration is adopted in which the area near the pen-indicated position is displayed in a constant brightness in the second field.

In such a configuration, when the figure displayed in the first field is dark and no signal can be obtained from the light pen, it becomes impossible to display the vicinity of the light pen indication with a constant brightness in the second field. This phenomenon will be explained using FIGS. 1 and 2.

Figure 1 shows the configuration of an existing video display device.
The optical signal of the RTI screen is detected by a light pen 2, converted into an electrical signal, and input to the amplification circuit 3. The signal amplified by the amplification circuit 3 is converted into a light penni value signal by the binarization circuit 4, and inputted to the n-th pulse detection circuit 5 which detects the n-th pulse to obtain the detection signal c, which is sent to the flip-flop. P6
is input as a set input. This flip-flop 6 is reset by the trailing edge pulse V of the vertical synchronizing signal V. Therefore, as the output of the flip-flop 6, a flip-flop 'output d is obtained which rises at the time of the detection signal c and falls in synchronization with the trailing edge pulse VL. , 8 counting operation is stopped. Note that the first counter 7 receives the clock pulse φ
, and the second counter 8 counts the flat synchronization signal H. Therefore, both counters 7 and 8 receive the detection signal c
The counting operation stops when ・ is output, and the outputs of counters 7 and 8 at that time correspond to the instruction address of light pen 2. The outputs of the counters 7 and 8 are input to latch circuits 9 and 10, respectively, and are latched in synchronization with the logical product 11 output e1 of the central pulse M of the vertical synchronizing signal V and the first and second field IH discrimination pulses a. be done. The outputs of these latch circuits 9 and 10 are input to matching circuits 12 and 13, respectively, and the other inputs of the roller matching circuits 12 and 13 are counters 16 and 17 that indicate the address of the image memory 18. output is used. Therefore, the first
When the address corresponding to the indicated coordinates of the light pen 2 detected in the field I matches the display address to be read from the memory 18, the matching circuits 12 and 13 output matching signals Fl and gl. Signal Fl, gl
The interval sampling circuits 14, 15 are triggered by the . When the section sampling circuits 14 and 15 operate in this way and the sampling signals 11 and j1 are obtained, these two signals 11 and j1, the first and second field discrimination pulses a, and the light pen switch signal SW, is gated by the AND gate 19, and a control signal k1 is obtained to control the multiplexer 20. On the other hand, the output from the image memory 18 addressed by the counters 16 and 17 passes through the multiplexer 20 and is converted into an analog signal by the D/A conversion circuit 21 to the CRTl drive level and displayed on the CRTl screen. , during the period of the control signal k1, various colors corresponding to a separately specified color signal (DAT) are displayed.

In this way, images are displayed on the CRTl screen, but if the optical signal from the CRTl screen is weak, that is, the CR
If the brightness of the Tl screen is low, the binary signal b cannot be obtained as shown by the broken line in FIG.

Therefore, at this time, the multiplexer control signal k1 cannot be obtained in the second field, and the content of the image memory 18 and the color signal (
DAT) becomes impossible, and the binary signal b of the light pen 2 cannot be obtained regularly. The present invention has been made to solve these problems, and will be described in detail with reference to FIG. 3 and subsequent figures.

FIG. 3 shows the configuration of the device of the present invention. Since it is the same as the conventional example shown in the figure, the explanation will be omitted.

The feature of the present invention lies in the latch timing for the latch circuits 9 and 10. That is, the output E2 of the logical product 11 which latches the address instruction data of the counters 7 and 8 with the latch circuits 9 and 10 is constituted by the output d of the flip-flop 6 and the central pulse □M of the vertical synchronizing signal.
Therefore, as shown in FIG. 4, the light pen 2 instruction address obtained in the first field I is latched by the latch circuits 9 and 10 immediately before the display of the second field I. Then, the light pen instruction address obtained in the second field (3) is latched by the latch circuits 9 and 10. As a result, when a dark screen corresponding to the contents of the image memory 18 is displayed in the first field I, the binary signal b of the light pen 2 cannot be obtained, and the output d of the flip-flop 6 cannot be obtained. , in the second field ■, the light pen instruction address obtained in the field before the previous one is stored in the latch circuits 9 and 10, so the match circuit 12,
13 operates, and coincidence signals F2, g2 are obtained. These coincidence signals F2, g2 drive section sampling circuits 14, 15,
Since sampling signal 12,j2 is output, AND gate 1
The logical product of 9 is obtained and a control signal K2 for controlling the multiplexer 20 is obtained. Therefore, the color data (DAT) given from the outside is displayed on the D/A conversion circuit 21 only during the period of this control signal K2, and if this is set to a bright enough color for the sensitivity of the light pen 1, , the light pen 2 binary signal b is obtained in this second field (2). As a result, when displaying a dark screen that corresponds to the contents of the image memory 18, the binary signal b of the light pen 2 is obtained from the previous field even if it is not obtained from the immediately preceding first field I. In addition, according to this configuration, the addresses corresponding to the light pen instruction addresses obtained in the second field (■) are sequentially sent to the image memory 18 as data. By rewriting, an image is constructed on the CRTl screen, and at that time, the light pennivalued signal b is used in the second field.
is always obtained, so even dark images that cannot be detected with the light pen 2 can be created using the light pen 2.

As is clear from the above explanation, according to the present invention, since the light pen instruction address is determined from the previous display field, it is possible to create even dark images below the detection level of the light pen, which was impossible in the past. It becomes possible to detect and create hot dark images, and a highly versatile video display device can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the internal configuration of an existing video display device, FIG. 2 is a waveform diagram for explaining its operation, FIG. 3 is a block diagram showing the configuration of the video display device of the present invention, and FIG. 4 is a block diagram showing the internal configuration of an existing video display device. It is a waveform diagram for explaining its operation, in which 1 is a CRT12 is a light pen, 4 is a binarization circuit, 7 and 8 are counters, and 9 and 1
0 is a latch circuit, 12 and 13 are matching circuits, 18 is an image memory, and 20 is a multiplexer.

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. A video display device comprising the following, wherein the first address means uses a light pen instruction address obtained in a previous display field as a determined address.