JPS5856135A - Light pen device - Google Patents

Abstract

PURPOSE:To obtain a lightweight, small-sized, and long-life light pen by employing optical constitution, and thus eliminating a mechanical part completely and providing only a cable atop of the pen. CONSTITUTION:Elements other than a light emitting elements 3, photodetectors 5 and 7, and a filter 6 are arranged in a device. An electric signal converted by the 1st photodetector 5 is amplified and shaped into a rectangular-wave pulse signal, and a comparator 10 selects only a signal with a prescribed level or above as an output B. On the other hand, the reflected light of special light from the light emitting element 3 passed through the filter 6 is converted by the photodetector 7 into an electric signal, which is processed similarly to obtain a pulse signal as an output A. Therefore, an output C changes through an inverter 14 and AND gates 15 and 16 as shown by the truth table in the figure which regards the outputs A and B as input conditions, Therefore, only when a pen tip is brought into contact with a CRT1 to supply light to only the photodetector 5, the pulse signal is obtained at an output terminal 17.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a light ben device that detects rusk light on a cathode ray tube screen, detects its position on the screen, and writes and erases data.

Generally, this type of device detects rusk light by pressing the tip of a light pen against the screen of a cathode ray tube, but a switch is provided that converts the incident light into meaningful information when this a is applied.

This switch usually consists of a mechanical switch,
The tip of the light pen is composed of a movable part, which works in conjunction with the tip of the light pen. However, since this type of switch is frequently operated, its on/off operations are frequent and there are problems with durability.

The present invention has been made in view of these points, and its purpose is to eliminate mechanically moving parts and simplify the structure of the light pen itself.

The present invention will be described below with reference to the drawings.

FIG. 1 is a configuration diagram showing a light pen device according to an embodiment of the present invention, where 1 is a cathode ray tube, 2 is a fiber cable whose cross section is as shown in FIG. 2, and 3 emits Δ special light such as infrared light. Light emitting element 4 drives light emitting element 3.

5 is a first light receiving element that receives the light introduced by the fiber cable 2, converts it into an electric signal and outputs it, and 6 is a special pulse generator such as infrared rays emitted by the light emitting element 3. A filter that allows only light to pass through, 7, is a second light receiving element.

As shown in the cross-sectional view of Fig. 2, the fiber cable 2 is composed of a set of 11, second and third cables (A), (B), and G, and the first cable (A) is a cathode wire. tube(
The second cable (b) is used to guide the special light from the light emitting element 3 to the tip of the cable 2. The third cable (c) is used to introduce and detect the emitted special light when it is reflected by some member, such as the tube surface of a CRT. These 3
In the first to third cables (a) to f9, the second and third cables (b) and (c) have smaller cross-sectional areas than the first cable (a).

This is a consideration to facilitate the detection of rusk light, which is the original function of the light pen device. Therefore, the fiber cable 2 is configured to have an appropriate length so that it can be freely routed. Further, the light emitting element 3, the first and second light receiving elements 5.
7, filter 6, and other components other than cable 2 are appropriately placed inside the device housing.

Incidentally, the light received by the first light-receiving element 5 is converted into a first electrical signal, and this first electrical signal is amplified by an amplifier 8 to a signal of an appropriate size, and then converted into a rectangular wave by a waveform shaping circuit 9. It is shaped into @11 pulse signal. Of the first pulse signals of the rectangular wave, only those having a predetermined level or higher are selected by a comparator IO and outputted as output -)K. On the other hand, the nine special lights that have passed through the filter 6 are converted into a second electrical signal by the second light receiving element 7, and this second electrical signal is output via the amplifier 11, waveform shaping circuit 12, and comparator 13 in the same way as above) is extracted as a second pulse signal. This eleventh second pulse signal is transmitted to the first and second light receiving elements 5.
．． This occurs only when 7 are each receiving light. Therefore, when each of the first and second light-receiving elements 5 and 7 receives light, the outputs a) and p> are in a state where a pulse signal exists, and for convenience, they are referred to as "1" here, indicating that no light is being received. Sometimes there is no pulse signal, and here "
0".

Outputs (A) and (B) of each comparator 10 and 13 are input to an inverter 14 and first and second AND gate circuits 15 and 16, respectively. These logic circuits are configured to control opening and closing of the gate of the second AND gate circuit 16 by the inverter 14 and the first AND gate circuit 15. That is, the gate of the second AND gate circuit 16 is controlled by the output (0) of the first AND gate circuit 15, and this output (0) is the output (A).

It changes as shown in the truth table shown in FIG. 3 with (B) as the input condition. Therefore, the gate of the second AND gate circuit 16 is opened only when the output (B) becomes 111. As a result, under this condition, the output terminal 17
The pulse signal output from the comparator 10 is the second
It passes through the AND gate circuit 16 and is taken out.

By the way, when the Lite Pen/ is actually used, its nib takes on various aspects. For example, there are situations as shown in FIGS. (2) is when the pen tip is inserted into something like the pen holder 18, and no light is applied to both the first and second light receiving elements 5 and 70. (3) is when the pen tip is directed into the air, and similarly, no light is applied to both the first and second light receiving elements 5, 7. In addition, ■ is when the pen tip is directed toward the screen of CR'rl, and the special light derived from the pen tip is reflected on the tube surface and received by the second light receiving element 7. Therefore, in this case, light is provided to both the first and second light receiving elements 5 and 7. (2) is a state in which the pen tip is pressed against the tube surface of the CRT 1 and is in close contact with it, and light is applied only to the first light receiving element 5. ■ is when the pen tip is directed toward a mere reflective surface 19 that does not emit light, and only the special light derived from the pen tip reaches the second light receiving element 7.
given to.

Therefore, in this usage mode, the comparator 10,
The conditions for each output (A) and (B) of 13 are as shown in FIG. In the light pen device, it is sufficient to enable the detection of the rask light only when the pen tip is in the state (3) in the usage modes (1) to (2). In FIG. 1, the inverter 14,
, the logic circuits of the second AND gate circuits 15 and 16 satisfy this requirement as shown in the truth table of FIG.

As described above, according to the present invention, it is possible to completely eliminate mechanical parts in the light pen device, and the tip of the pen can be simply a cable, making it possible to reduce the weight and size.

As described above, the present invention emits special light from the tip part to
By simultaneously detecting the rask light and the object reflected light of the special light at the tip mentioned above, the logical product of both detection outputs is taken, and the input condition for this logical product is set to the state in which the detection output of the special light exists. By setting this as an involuntary input and the state in which the detection output of the rusk light exists as a significant input, it is possible to obtain the detection output of the rusk light only when the tip is pressed against the CRT screen. be.

[Brief explanation of drawings]

Fig. 1 shows the configuration of a device according to an embodiment of the present invention, Fig. 2 is a cross-sectional view of an embodiment fiber cable, Fig. 3 is a truth table of an embodiment logic circuit, and Fig. 4 shows how the tip of the light ben is used. FIG. 5 is a perspective view showing the relationship between usage and logic circuits. 2, (a), 5, 8 ~ IO... first light receiving means, 2, (
B), 3, 4...Special light generating means, 2, (C), 6,
7.11-13... second light receiving means, 14, 15...
1st AND circuit, 16...2nd AND circuit.

Claims (1)

[Claims] (1) A first light receiving means that receives the rusk light of the cathode ray tube from the tip and converts it into a first electric signal, and a special light generator that emits special light such as infrared rays that is distinguished from the rusk light from the tip. 211th! means for receiving the special light reflected by the object from the tip portion; a second light receiving means for converting into an air signal; a state in which the first electric signal is outputted from the first light receiving means is a significant input; a first AND circuit that uses the output of the first AND circuit as a random input; and a second AND circuit that gates the 1'# signal with the output of the first AND circuit; A Lightven device that is characterized by extracting Rusk light as a detection output.