JPS6031248B2 - light detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a photodetection device that detects the position of a bright spot on a screen using a photodetection element, and an object of the present invention is to improve the resolution of position detection.

Light-Ven type photodetectors display characters or light-emitting points on a cathode ray tube, detect the scanning light with a Light-Ven photodetection element, and obtain information from the detected position.The Light-Ven type photodetection device is used in computer terminals and the like. The positional resolution on the cathode ray tube in this device is determined by the optical resolution of the photodetector, and therefore the resolution of position detection may not be improved. Consider this in Figure 1.

In FIG. 1, the marks a to i indicate points (dots) to be detected arranged every few scanning lines on the cathode ray tube, that is, detection positions. For example, if the shaded area 1 is the detectable range of the Light Ben photodetection element, then each a to
In order to detect point i, the light emitting area (cross point) of each dot must be the diagonal line of A, otherwise adjacent light emitted light will be detected and an error will occur. That is, in Fig. 1, if the detectable range of the element is 1, and the light emitting area at each detection point (dot) is greater than or equal to the area indicated by the diagonal line in A, then the dot to be detected and the adjacent dot in the range of 1 are Light emission enters, making detection impossible. Therefore, if the distance L between the dots, that is, the detection positions, is constant, the area of the bright spot of each dot cannot be made larger than A in FIG. 1.
Further, even if the interval between each dot is made smaller than that shown in FIG. 1, a plurality of dots fall within one range, making position detection impossible. Therefore, in view of such disadvantages, the present invention
Even if the area of the bright spot is made larger than that of the subordinate, or the distance between the dots is made smaller, or the detection range of the detector is made larger, position detection on the display screen becomes possible and the optical resolution increases. It is characterized by improvements.

That is, the present invention improves the detection resolution between, for example, a detection circuit or its amplification circuit and a detection signal output circuit, immediately after detecting a bright spot of a cathode ray tube with a photodetection element and obtaining a signal at the detection position. A gate circuit is provided for the purpose of detecting a signal, and a sampling pulse that matches the point to be detected and has a pulse width smaller than the scanning time interval between the detection points is applied to the gate circuit, and the detection signal is extracted using this sampling pulse. It is characterized by:

DESCRIPTION OF THE PREFERRED EMBODIMENTS A photodetecting device according to an embodiment of the present invention will be described with reference to FIGS. In the present invention, for example, when detecting bright spots of a plurality of detection points arranged at intervals L as shown in FIG. These pulses Pv, PH and the photodetection signal are gated using vertical and horizontal extraction gate pulses Pv, PM whose width is narrower than L and has a pulse width that does not interfere with detection (1 in Figures 3, 4, and 5). The detection signal from the element is output from the gate circuit only when both gate pulses Pv and PH are applied.

The width of each gate pulse Pv, PH is smaller than the so-called raster scanning period for displaying a bright spot. The circuit configuration of the main part of the detection device which outputs only when is applied is shown.

1 is a circuit for detecting and amplifying a signal detected by a photodetector (not shown), and 2 is a waveform shaping circuit.

3 is an AND gate circuit to which the signal (detection signal) from 2 and sampling gate pulses Pv and PH are applied.

4 is a direct extraction pulse synthesis circuit into which a signal from a vertical deflection circuit (not shown) for image display is inputted from a terminal 6, and generates a narrow vertical extraction gate pulse Pv in synchronization with this signal; A signal from a horizontal deflection circuit for display is input to a terminal 7, and this is a horizontal sampling pulse synthesis circuit which generates a horizontal sampling gate pulse PH similar to Pv from this signal.

In FIG. 2, the photodetection signal input to the gate circuit 3 is Pv
, PH is output as a position detection signal from the output terminal 8 only when the signals PH, PH are applied.

That is, when the three signals of the photodetection signal, horizontal, and direct extraction gate pulse are input together, the position detection signal is output,
Even if there are signals or noises from other detection points during the period when there is no sampling gate pulse, they are not output at all, and the resolution can be improved as described below. In FIG. 3, gate pulses Pv and PH are added to increase the area of twill point A indicating each detection point.

That is, assuming that the detection range 1 of the photodetecting element and the dot spacing L to be detected are the same as in FIG. Since signals are output, outputs from both positions cannot be obtained unless the area straddles the detection area surrounded by the dashed line with a width of 1. Therefore, even if the twill points overlap as shown in FIG. 3, a predetermined position can be detected. In this way, increase the bright spot area (A, > A)
be able to. FIG. 4 shows an example in which the distance of the detection position is shortened in the present invention.

That is, if the detectable range 1 of the detector and the size of the foot point A of each detection point are constant as in FIG.
Compared to the figure, the distance between the coin points and the distance between the detection points can be shortened. As mentioned above, even if 1 overlaps multiple bright points, the width 1 corresponding to Pv and PH within the twill point
According to the present invention, position detection is possible as long as the portions do not overlap, and the distances between bright spots and detection points are shorter than in FIG. 1, making it possible to improve disassembly. FIG. 5 shows a case where the detectable range 0 of the detection element can be made larger than 1 when the distance L between each detection point and the size of the traverse point A are kept constant as shown in FIG.

That is, in this case, in the present invention, a detector with a large detectable range can be used, and the detection operation becomes easy. As described above, according to the present invention, it is possible to improve the accuracy of position detection on a screen, and it greatly contributes to position detection using light.

[Brief explanation of the drawing]

Fig. 1 is a detection state diagram of a display screen in a conventional photodetection device, Fig. 2 is a schematic circuit diagram of a main part of a photodetection device according to an embodiment of the present invention, and Figs. It is a detection state diagram of the display screen in a detection device. 1... Photo detection amplification circuit, 3... Gate circuit, 4... Flower direct extraction pulse synthesis circuit, 5...
...Horizontal sampling pulse synthesis circuit, Pv, PH...
...Extraction gate pulse. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Scope of Claims] 1. A display surface on which a plurality of bright spots are displayed at predetermined intervals using scanning pulses, a detection circuit that detects light from the bright spots on this display surface using a photodetector, and It is characterized by comprising a gate circuit which extracts the detection signal of the detection circuit with a sampling pulse having a pulse width smaller than the scanning time interval between the bright spots, and obtains a signal of the detection position of the bright spot from the gate circuit. Photodetection device. 2. The photodetection device according to claim 1, wherein the display surface is a display screen of a cathode ray tube. 3. The photodetection device according to claim 1, wherein the extraction pulse consists of a horizontal gate pulse and a vertical gate pulse.