JPS5826579B2 - Light Pen No.1 - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a raster scan type display device in which, while viewing an image on a cathode ray tube, etc., in the display, a part of the image that is particularly desired to be emphasized is
Draw points, arrows, etc. by applying a light pen,
This invention relates to an auxiliary device for detecting the position of a light pen, which reliably detects the position of the light pen in order to superimpose it on the original picture.

As is well known, a light pen detects the position of light on a cathode ray tube using phototransistors, photodiodes, etc., but when the position on the screen to be detected is a black part of the screen or a part of dimly lit area. If there is, the light pen will not be able to detect that position.

For this reason, conventionally, the Eirin signal forming the screen was raised to a white level for every field, so that the light pen would be sensitive to this strong light.

However, when detecting consecutive positions with the light pen mentioned above, the white of the screen and the original image change alternately, so
This has the disadvantage that bright and dark objects exhibit significant flicker, making it difficult to see the video signal and being bad for eye health.

However, when drawing a line or giving directions with an arrow, once the position is detected, the pen is only moved a short distance in a short period of time, so if the pen is nearby If you only send the white level, there is no need to set the entire field to white level like in the past.
Therefore, the difficulty in viewing due to the above-mentioned flicker can be prevented.

The present invention is characterized by a configuration that embodies this idea, and this will be explained below with reference to the drawings.

FIG. 1 shows the configuration of the present invention in a block circuit diagram. 1 is an input terminal for an Eirin signal, 2 is an input terminal for a detection signal detected by a light pen, and 3 is a horizontal synchronizing signal multiplied by, for example, 256 times. 4 is a clock signal input terminal in the Y-axis direction, which corresponds to the horizontal synchronization signal, and 5 is an information input terminal that supplies information 1 when the light pen is switched on. , 6 are input terminals for inputting arrows, points, line drawing signals, etc. to desired parts on the screen.

Reference numerals 7 and 8 indicate an X-axis counter to which the detection signal (FIG. 2A) and clock signal from the light pen are respectively input, and detect the position of the light pen on the cathode ray tube;
This is an axis count, and a numerical value corresponding to the position of the light pen 1 is always input.

The deduders 9 and 10 operate to calculate the sum of the number inputted by the light pen detection signal and the overlay bit of the clock signal, and their respective outputs are applied to the AND circuit 11 to determine the position of the light pen 1. It is supplied to the AND circuit 12 as a signal to create a white level area around the area.

(FIG. 2B) An IJ l-IJ gable monomulti bi-break 13 is connected to the terminal 2, and its output side is connected to the AND circuit 14 together with the input terminal 5 side.

This retriggerable mono multi-bi break 13 is t-IJ triggered by the detection signal from the light pen,
It is in a metastable state for a certain period of time determined by the time constant of the circuit, and outputs a pulse signal whose pulse width is this certain period of time, but if it is re-triggered while in the above-mentioned metastable state, , it operates so as to maintain the above-mentioned quasi-stable state until after the above-mentioned predetermined time has elapsed from this re-triggering (FIG. 2C).

Further, the AND circuit 12 is supplied with a switch input from the input terminal 5, and its output and the AND circuit 1
The four outputs are both supplied to the OR circuit 15, and this OR output (D in FIG. 2), the video signal, and the line drawing signal are mixed in the mixing circuit 16, The body signal output is displayed on a cathode ray tube.

Accordingly, based on the detection information on the X and Y axes, only the predetermined area is reliably set to the white level, the position of the light pen is reliably detected, and display can be performed using the line drawing signal or the like.

Therefore, in order to perform detection reliably, the number of bits for taking the above sum in the decoders 9 and 10 is set so that the above region has an area that can be reliably tracked, taking into consideration the moving speed of the light pen. There is a need.

In order to detect the position of the light pen in the above-described capture, first the light pen is placed on a predetermined position on the screen of the cathode ray tube.

If the designated area is at the white level and a sufficient detection signal is obtained from the light pen, the position in the X-axis and Y-axis directions on the screen will be determined by counters 7 and 8, respectively.
can be easily detected.

Based on this detected position information, normal light pen functions such as drawing lines are possible.

Further, the position information output from the counter 7.8 is processed by the decoders 9 and 10 and the AND circuit 11, and becomes a signal that sets a white level within a predetermined area including the position of the light pen as described above. and is supplied to the AND circuit 12.

Then, the light pen is switched on and the information input terminal 5
When the input is 1, a signal for setting the predetermined area to the white level passes through the AND circuit 12 and is sent to the mixing circuit 16 via the OR circuit 15.

Therefore, a white level region is formed around the light pen position on the cathode ray tube, and the light pen position is indexed.

At this time, the detection signal from the light pen is obtained without any defects at approximately equal intervals of approximately one field period, and the above-mentioned IJ l-IJ
It is supplied to the Gable Mono Multivi Break 13.

By setting the output pulse width of this mono-multi-by-break 13, that is, the initial duration of the metastable state determined by the above-mentioned time constant, to be larger than the ■ field, for example, about 1.5 fields, the above-mentioned As long as the detection signal continues to be supplied, the mono-multi-vibration brake 13 continues to maintain a quasi-stable state because the IJ l-trigger is maintained, and the output does not change (FIG. 2C).

Next, if the light pen is applied to a black or dark area on the screen of the cathode ray tube, the detection signal will not be obtained even if the light pen is switched on.

Therefore, the position cannot be detected by the counter 7.8, and the position information cannot be obtained.

At this time, the retriggerable mono-multi-bi-break 13 detects a time elapsed by the output pulse width (for example, about 1.5 fields) from the previous pulse of the detection signal (the second pulse in FIG. 2A). Afterwards, the quasi-stable state returns to a stable state, and the output rises as shown in FIG. 2C.

The output of this mono-multi-by-break 13 is supplied to the cathode ray tube as a sandwiched signal output through the AND circuit 14, the OR circuit 15, and the mixing circuit 16, so that the entire display screen area after the above-mentioned rise timing becomes a white level. .

When the area to which the light pen is applied also reaches the white level due to such white level display, a sufficiently strong detection signal can be obtained from the light pen.

Therefore, the position is detected by the counter 7.8, and the retriggerable monomulti-by-break 13
is triggered and the output falls as shown in Figure 2C.

Further, when the position of the light pen is detected by the counter 7.8, this detected position information is output to the decoders 9 and 10.
and is subjected to arithmetic processing in the AND circuit 11, so that
A signal is generated that sets a predetermined area including the detected position to a white level, and the area around the position of the light hen 1 is displayed at a white level.

As described above, the present invention provides a raster-scanner type display device with position detection means having an X-axis counter and a Y-axis counter for detecting the position of a light pen on a cathode ray tube, and detects the position of a light pen on a cathode ray tube. By calculating the output, define the area that includes the relevant position of the light pen, and when the area is black or dark and the light pen does not receive a detection output, the screen will be displayed until the detection output is obtained. By turning the area white to detect the position of the light pen, and supplying the detection output to the position detection means and processing the output, only the above area is made white, and the position of the light pen is determined by obtaining the above detection. By making it as an index on the cathode ray tube, compared to the conventional method that detects the position of the light pen by setting the white level in every other field, it is less difficult to see due to flicker and has a negative impact on eye health. It is possible to eliminate harm, and moreover, it is possible to clearly indicate the position on the screen and to superimpose indicators such as arrows on the screen.

[Brief explanation of the drawing]

FIG. 1 is a block connection circuit diagram illustrating an embodiment of the present invention, and FIG. 2 is a time chart of pulses in various parts of the required circuit. 7...X-axis counter, 8...Y-axis counter, 9°102. Decoder, 13... Retriggerable mono multivi break.

Claims (1)

[Claims] 1. In a raster scan type display device, a position detection means having an X-axis counter and a Y-axis counter is provided to detect the position of the light pen on the cathode ray tube, and the output from each counter is processed to detect the position of the light pen. Define an area that includes the relevant position, and when the area is black or dark and the light pen does not receive a detection output, the screen is made white until the detection output is obtained and the position of the light pen is detected. At the same time, by supplying the detection output to the position detection means and processing the output,
A light pen position detection device in which only the above area is made white, and the position of the light pen is indicated on the cathode ray tube.