JPS62229423A - Light pen input device - Google Patents

Abstract

PURPOSE:To easily detect the abutting center position of a light pen by differentiating a light pen output signal made of plural pulses and detecting a timing when the level of the differentiated pulse passes by a reference value as the abutting center position of the light pen. CONSTITUTION:The differentiation pulse dLP2'' in the visual field of the light pen is composed of plural differentiation pulses, and a point C in the tailing part of the differentiation pulse dLP2m'' having the maximum level approximately corresponds to the center in the visual field of the light pen. Accordingly resistances R9 and R10 set a reference value VRC corresponding to the point C, and the reference value VRC is compared with the differentiation pulse dLP2'' composed of plural pulses, whereby a comparator Q5 outputs a pulse signal CP at the timing when the differentiation pulse dLP2m'' with the maximum level exceeds the reference value VRC. The abutting center position of the light pen can be decided from the tailing edge of the pulse signal CP.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a light pen input device that receives a pen output signal to a light pen.

(Prior Art) As is well known, a light pen has a photodiode at its tip, receives raster light by pressing this tip against the display surface of a cathode ray tube display device, and outputs data periodically at the timing of the light reception. The light pen is configured to output a signal, and by comparing the output signal generation timing of the light pen with a signal representing the scanning position of the raster destination,
It is used to detect the position of a light pen in contact with the display surface of a cathode ray tube display device, and perform various data processing depending on the detected position.

Conventionally, as shown in FIG. 3, a light pen input device that receives an output signal from such a light pen includes an amplifier Q2 that amplifies the output signal of a phototransistor Q1 installed at the tip of the light pen 1; It is composed of a comparator Q3 that compares the amplified output signal @LP' of the light pen with a reference value vR determined by resistors R1 and R2, and sends out an output signal LP'' with a relationship of LP->VR from the output terminal. , when the tip of the light pen 1 is brought into contact with the surface of the cathode ray tube display device, as shown in FIG.
A line 1 to pen output signal LP having an envelope shape corresponding to the directivity characteristic of line 1 is output. This light pen output signal LP is amplified by the amplifier Q2 and then compared with the reference 'ItlIVR by the comparator Q3, thereby being shaped into a pulse waveform as shown in FIG. 4(b) and outputted from the output terminal to the outside. Sent out.

By the way, the width A of the envelope of the light pen output signal LP is determined by the field of view of the light pen itself and the phototransistor Q1.
The directional characteristics of the phototransistor Q1 and the mounting of the phototransistor Q1 change depending on the angle. Therefore, the envelope width B of the output signal LP'- shaped by the comparator Q3 also changes. Therefore, if the timing of 1/2 of the envelope width B of the output signal Ll"' is determined as the center position of the light pen, erroneous placement may appear in the center position determination result due to the directivity characteristics of the phototransistor Q1, etc. become.

Therefore, conventionally, 77f1 to transistor Q1 were not only simply attached to the tip of light pen 1, but also the input range of the raster end from the cathode ray tube display device was placed in front of the light receiving part of phototransistor Q1, as shown in the cross-sectional view of FIG. A photoguide 2 composed of a transparent acrylic cylinder etc. that narrows the
The directivity characteristics and mounting of the phototransistor Q1 are designed to prevent the envelope width B of the output signal @LP-- from varying due to angle or the like.

However, in this way, the light pen output signal LP"'
Even if the envelope width B of the light pen 1 can be made almost constant, in order to determine the contact center position of the light pen 1, the number of pulses n within the envelope width B is counted, and the calculation to find the 1/2 position is necessary for determining the contact center position of the light pen 1. 1 is required each time the light pen 1 is brought into contact with the display surface of the cathode ray tube display neck, and there is a problem in that it is troublesome to detect the center position of the contact of the light pen 1.

(Problems to be Solved by the Invention) As mentioned above, in the conventional light pen input device,
There is a problem in that it is troublesome to detect the center of contact of the pen.

The present invention solves the above-mentioned problems, and aims to provide a light pen input device that can easily detect the contact center position of a light pen.

[Structure J of the Invention (Means for Solving Problems) A light pen input device according to the present invention includes a differentiating circuit that differentiates an output signal of a light pen, an integrating circuit that integrates an output signal of the differentiating circuit, and The device includes a comparator that compares the output signal of the integrating circuit with a predetermined reference value and outputs a signal synchronized with a timing corresponding to approximately the center position of the field of view of the light pen.

(Function) A light pen output signal output in synchronization with the raster cycle within an envelope width corresponding to the light pen field of view is differentiated by a differentiating circuit and then integrated by an integrating circuit. Then, the fourth
As shown in the figure (a), the light pen output signal consists of multiple pulses synchronized with the reception timing of the raster light.
Each of the pulses becomes a differential pulse synchronized with the rising edge.

Among these, the differential pulse with the highest level corresponds to the timing from lie 1 to approximately the center position of the pen field of view. Therefore, by comparing this maximum level differential pulse with a reference value, a signal synchronized with the timing corresponding to the contact center position of the light pen can be extracted from the comparator.

Therefore, it is no longer necessary to calculate the center position of the contact each time the light pen is brought into contact with the brown tube display device. Furthermore, even if the directivity characteristics or the contact angle of the phototransistor change, the comparator detects the timing when the maximum level differential pulse passes the reference value, making it possible to accurately detect the contact center position. can.

(Example) Hereinafter, the present invention will be described in detail based on the illustrated example.

FIG. 1 is a circuit diagram showing an embodiment of the present invention, in which a phototransistor Q1 of a light pen 1 has an emitter resistor R[
is connected, and the collector resistor RC is also connected, the emitter resistor RE outputs a positive polarity signal LPI when raster light is received, and the collector resistor RC outputs a negative polarity signal @ LP when raster light is received. 2 is output.

The positive polarity light pen output signal LPI output from the emitter resistor RE is amplified by the amplifier Q2 as in the conventional circuit, and then compared with the reference value VR by the comparator Q3, and the LP
When l>VR, it is output from comparator Q3 as signal LP1°.

On the other hand, the negative polarity light pen output signal iP2 output from the collector resistor RC is the capacitor 1s01.

It is input to a differentiating circuit DIF consisting of a transistor Q4, bias resistors R5 and R6, and a collector resistor R7,
Here, it is converted into a differential pulse dLP2°. That is,
The light pen output signal LP2 shown in FIG. 2(a) is differentiated by the capacitor C1 and converted into a differentiated pulse dLP2 having positive and negative polarities as shown in FIG. By inputting the differential pulse d of only the positive polarity portion as shown in FIG. 2(C),
Converted to LP2°.

This differential pulse dlp2° is then integrated by a capacitor C2 constituting an integrating circuit, shaped into a waveform as shown in FIG. 2(d), and inputted to a comparator Q5.

Here, within the field of view of the light pen, the differential pulse dLP2° is composed of a plurality of differential pulses, which are not shown in FIG.
The zero point of the falling portion of P2m''' corresponds to approximately the center position of the field of view of the light pen.

Therefore, the reference corresponding to the 0 point (aVRC is set to resistor R9 and R
By comparing this reference value VRC with a plurality of differential pulses dLP2°'', the comparator Q5 outputs the differential pulse dl-P2m'', which has the maximum level, at the timing when it exceeds the reference value VRC. A pulse signal QCP as shown in FIG. 2(e) is output.

Therefore, the contact center position of the light pen can be determined based on the falling edge of this pulse signal CP. In this embodiment, since the center texture detection signal is output as a center texture detection signal having a pulse width corresponding to one raster period in synchronization with the falling edge of the pulse signal CP, the monostability is achieved by the falling edge of the pulse signal CP output from the comparator ff1Q5. Trigger multivibrator Q6, and one shock 1 with approximately 1.5 raster period width from this monostable multivibrator Q6.
-Pulse WP! Generate this one shock 1 ~ pulse W
The AND gate Q7 calculates the logical product of P and the output signal LPI° of the comparator Q3, and the logical product signal is output as the center position detection signal @CDP of the light ben 1. Note that the pulse width of the one-shot pulse WP is determined by the resistance R.
11 and capacitor C3.

According to this embodiment, the light pen output signal consisting of a plurality of pulses is differentiated, and the timing when the level of the differentiated pulse passes the reference value is detected as the contact center position of the light pen. Even if the directivity characteristics of the phototransistor vary or the contact angle changes, the center position of the contact can be accurately and easily determined.

Note that if it is not necessary to output the center position detection signal @ CD P having a pulse width corresponding to one raster period, it is possible to output the output signal CP of the comparator Q5 as it is. In this case, amplifier 5Q2, comparator Q3 . Seven stable multivibrator Q6° and gate Q7 becomes unnecessary.

[Effects of the Invention] As explained above, according to the present invention, a light pen output signal consisting of a plurality of pulses is differentiated, and the timing when the level of the differentiated pulse passes a reference value is set as the contact center position of the light pen. Because of this detection, even if there are variations in the directivity characteristics of the phototransistors or the contact angle changes, the center position of the contact can be accurately and easily determined.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing an embodiment of the present invention, Fig. 2 is a waveform diagram showing input and output waveforms of each part of the embodiment, Fig. 3 is a circuit diagram showing a conventional horn device containing a light pen, and Fig. 4 is a circuit diagram showing an example of the present invention. This figure is a waveform diagram showing the input and output waveforms of the conventional device shown in FIG. 3, and FIG. 5 is a sectional view of the tips of the light receiving area 1 to the pen provided with means for narrowing the light receiving range. 1...Light pen, Ql...Phototransistor,
C2...Amplifier, C3, C5...Comparator, C4...
・Transistor, C6... Monostable multivibrator, C7・
...And gate, C1... Capacitor, DIF...
・Differentiating circuit, C2... Capacitor agent for integrating circuit Patent attorney Nori Chika Ken Sokuma Hiro Uji DIF C4:) Ranzu Mata Nu C5: Yusoft Cloud 1 Fig. 1 Fig. 2 Fig. 3 Tsuyoshi-8-1 Figure 4, Q+ 50

Claims (1)

[Claims] A light pen input that receives an output signal from a light pen that has a phototransistor at its tip, receives raster light on the display surface of a cathode ray tube display device, and outputs a signal synchronized with the timing of the light reception. The device comprises a differentiating circuit for differentiating an output signal of a light pen, an integrating circuit for integrating an output signal of the differentiating circuit, and comparing the output signal of the integrating circuit with a predetermined reference value to determine the field of view of the light pen. A light pen input device equipped with a comparator that outputs a periodic signal at a timing corresponding to approximately the center position.