JPH03210421A - Position detector - Google Patents

Abstract

PURPOSE:To simplify a structure by projecting a sample to be detected to a semiconductor position detecting element equipped with at least two output electrodes and detecting the position of the sample based on outputs of the respective output electrodes. CONSTITUTION:A light receiving element 12 using a semiconductor position detecting element is equipped with output electrodes 12a, 12b while a sample 13 to be detected is placed between a light source 11 and the element 12 wherein outputs according to the position of the sample are obtained from the electrodes 12a, 12b to be processed in a signal processing circuit 10. Thus only a single light receiving unit is required.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a position detection device capable of detecting the position of a detected object. More specifically, the present invention relates to a position detection device suitable for detecting the position of a detected object, such as when detecting the widthwise position of a running tape edge in a tape running system of a magnetic recording/reproducing device. .

(Prior Art) As shown in FIG. 3, a conventional position detection device includes a light source 1 such as a light emitting diode, and a light source 1 emitted from the light source 1.
It consists of a light-receiving element 2 such as a photodiode or a phototransistor that receives light, and detects a change in the amount of light received when a detected object 3 interrupts the space between the light source 1 and the light-receiving element 2 from the output signal of the light-receiving element 2. By this, the position of the detected object 3 is determined.

Further, as shown in FIGS. 4 and 5, a conventional position detection device includes a light source 1 such as a light emitting diode, and two light receiving sections 2a and 2b that receive light l from the light source 1. One of the light receiving parts 2b is shielded from light by the detected object 3 between the light source 1 and the light receiving element 2, and the light l from the light source 1 is always incident on the other light receiving part 2a as a reference light. There are things that can be arranged and used in the same way.

The output of the light receiving section 2a of the light receiving element 2 of this position detection device is supplied to an amplifier circuit 4a, the output of the light receiving section 2b of the light receiving element 2 is supplied to an amplifier circuit 4b, and each amplifier circuit 4a, 4b
The output voltages v1 and v2 are input to the differential amplifier circuit 15. The differential amplifier circuit 5 is provided to compare the output voltage v1 and the output voltage (2) to obtain a position detection output (4).

Therefore, according to this position detection device, the difference between the output voltage from the reference light receiving section 2a and the output voltage from the detection light receiving section 2b, which serve as a reference, varies with the movement of the detected object 3. By making this voltage difference (Vs) correspond in advance to the position of the detected object 3, the position of the detected object #3 can be detected.

(Problem U to be solved by the invention) However, the position detection device as shown in FIG. 3 can only detect two states: whether or not the detected object 3 is present.
It is not possible to detect the position of the detected object 3, and therefore it can only be used for simple purposes.

Further, the conventional position detecting device shown in FIG. 4 requires a light receiving section for reference light as well as a light receiving section for position detection as a light receiving element, and has a drawback that the structure is complicated. Furthermore, the conventional position detection device described above is divided into two parts: a light receiving part for position 1 detection and a light receiving part for reference light, and it is necessary to always allow light to enter one of the light receiving parts. For,
It has the disadvantage that its uses are limited.

An object of the present invention is to provide a position detection device that can detect the position of a detected object with a simple structure and has a high degree of freedom of use.

(Means for Solving the Problem) In order to achieve the above object, the position detection device of the present invention is provided! teeth,
A position detection device that includes a light source and a light receiving element that receives light from the light source, and detects the position of a detected object on an optical path from the light source to the light receiving element based on an output signal of the light receiving element. A semiconductor device detection element is used in which the element is provided with at least two output electrodes, and from each of the output electrodes an output can be obtained according to the position of incident light on the light receiving surface, and the above-mentioned object to be detected is placed on the light receiving surface of the semiconductor device detection element. The arrangement is such that a light-shielded portion and a light-unshielded portion are projected, and the position of the object to be detected is detected based on the output from each of the output electrodes.

(Function) Therefore, when the light from the light source is incident on the semiconductor device detection element, a photocurrent that is inversely proportional to the ratio of the irradiation surface to the light shielding surface is divided and output from the output electrode.

For example, as shown in FIG.
Let L be the length of , and let X be the length of the portion of the semiconductor device detection element 12 that is shaded by the detected object 13 from the lower end in the drawing. In addition, the lower end of the semiconductor device detection element 12 in the drawing is taken as the origin (x=O), and the photocurrent when the light ρ is hitting the entire light-receiving surface S of the semiconductor device detection element when x=O is 10 shall be.

The photocurrent I when the light-receiving surface S of the conductive position detection element 12 is shaded by X by the detected object 13 is 1=Io (L-x) ・”(
1) At this time, the output electrodes 12a and 12b emit light #! divided at the position of point X as shown in the following equation. X style 11
．． 12 is output.

1i=1-S-...(2) 12=1”-2Δ ... (3) Next, the above (2) Finding the ratio of equation (3), we get 1i 1X =(L/x)-1 ... (4) becomes.

From the above formula (4), when calculating X, we get becomes.

Therefore, the output electrodes 12a, 1 of the semiconductor device detection element 12
The position of the object to be detected 13 can be detected by extracting the photocurrent 11.12 from 2b and calculating the equation (5).

(Example) Hereinafter, the configuration of the present invention will be described in detail based on an example shown in the drawings.

FIG. 2 shows a principle diagram of an embodiment of the present invention.

The position detection device of the present invention includes a light source 11 such as a light emitting diode.
and a light receiving element 12 that receives the light l from the light source 11, and the position of the detected object 13 on the optical path from the light source 11 to the light receiving element 12 is determined between the light receiving surface and the light shielding surface of the light receiving element 12. It is configured so that detection can be performed by photocurrent output according to the ratio. This position detection device uses a semiconductor device detection element (PSO) as the light receiving element 12.

This semiconductor device detection element 12 is composed of two layers on the front surface of a flat silicon plate, an N layer on the back surface, and one layer in between, and photoelectrically converts incident light l and transfers the photocurrent to the output electrode. It is configured to be able to perform divided output from 12a and 12b. This semiconductor device detection element 12 is equipped with at least two output electrodes 12a, 12b, and outputs are obtained from each of the output electrodes 12a, 12b according to the position of the incident light on the light receiving surface S. .

The position detection device is arranged such that a portion shaded by the detection target #13 and a portion not shaded are projected onto the light receiving surface S of the semiconductor device detection element 12, and each of the output electrodes 1
Input the outputs from 2a and 12b to the signal processing circuit 10,
In this signal processing circuit 10, the above-mentioned (1)2 to (5)
The configuration is such that the position of the detected object 13 is detected by processing the equation. Note that the electrode 12c is a bias south pole, and a voltage of 10 cm is applied.

Here, as shown in FIG. 1, the signal processing circuit 10 converts the output current from each output electrode 12a, 12b into a voltage V1. V2
A current-voltage converter 14a that converts the current into voltage.

14b, an adder 15 that adds the voltage v1゜■2 from the current-voltage converters 14a and 14b, and the voltage v1 from the current-voltage converter 14a and the output from the adder 15 (
Vl +V2) is taken in, and ■1/ (V+ +V2
).

Since the present invention is configured as described above, it operates as follows.

First, from the light source 11 to the semiconductor device detection element 1 which is a light receiving element.
Gives light 2 to 2. At this time, when the light-receiving surface S of the semiconductor device detection element 12 is shaded by X by the detected object 13, the photocurrent I is given as shown in the above-mentioned equation (1). At this time, the output of the semiconductor device detection element 12 is connected to the pole 12a.

From 12b, the above-mentioned (2) and (3
) is output as a photocurrent It, 12.

The photocurrent 11I2 from the output electrodes 12a and 12b is
The voltages Vl and V2 are input to the current-voltage converters 14a and 14b of the signal processing circuit 10 and converted into voltages Vl and v2. +, is proportional to 12.

Voltage Vl from the current-voltage converters 14a, 14b,
V2 is applied to adder 15. The adder 15 adds the voltages v1 and v2 and outputs the result as an output voltage (V1+
V2).

The output voltage (Vl +V2) of the adder 15 is the output voltage of the divider 1
6 is input. The output voltage 1 from the current-voltage converter 14a is also input to the divider 16.

The divider 16 calculates a modified version of the above equation (5).

Therefore, the output electrode 12a of the semiconductor device detection element 12
The position of the detected object 13 can be detected by taking out the light S current It , 12 from , 12b, converting these currents into voltages, and then calculating the above equation (5) 1.

Although the above-described embodiments are examples of preferred embodiments of the present invention, the present invention is not limited thereto, and various modifications can be made without departing from the gist of the present invention.For example, in each of the above-mentioned embodiments, Although a one-dimensional semiconductor device detection element having two output electrodes is used, a two-dimensional semiconductor device detection element having four output electrodes may also be used. In this way, two-dimensional semiconductor device detection By using the element, it is possible to detect not only the vertical movement of the tape, but also the inclination of the tape.

(Effects of the Invention) As is clear from the above description, the position detection device of the present invention is inversely proportional to the area ratio between the blocked portion and the unblocked portion of the light from the light source that irradiates the semiconductor device detection element. Since the photocurrent is divided and outputted from at least two output electrodes and the position of the object to be detected is detected from these currents, the position of the object to be detected can be detected accurately with a simple structure.

In addition, the position detection device can detect not only the presence or absence of an object to be detected, but also its position and inclination, so it has a wide range of uses. It can be applied to devices. In this case, the position of the center of gravity of the part not covered by the tape is being measured, not the position where the light is shining, and the relative center of gravity position changes linearly as the tape moves in the tape width direction. , the position of the edge of the tape can be detected. According to such a device, the vertical movement of the tape can be detected in an analog manner, and even if the tape edge is jagged, the center of gravity position is given in principle, so there are few errors.

[Brief explanation of drawings]

FIGS. 1A and 1B are explanatory diagrams showing the principle of the present invention. FIG. 2 is a principle diagram showing an embodiment of the present invention. FIG. 3 is a diagram showing an example of a conventional position detection device. FIGS. 4 and 5 are principle diagrams showing other examples of conventional position detection devices. DESCRIPTION OF SYMBOLS 10... Signal processing circuit, 11... Light source, 2... Light receiving element, 12a, 12b --- Output electrode, 3... Detected object, 4a, 14b... Current-voltage converter, 5 ...adder, 6...divider. Patent issuer Japan Broadcasting Corporation Agent Sankyo Seiki Seisakusho Co., Ltd.

Claims (1)

[Claims] A position detection device that includes a light source and a light receiving element that receives light from the light source, and detects the position of a detected object on an optical path from the light source to the light receiving element based on an output signal of the light receiving element. A semiconductor device detection element is used in which the element is provided with at least two output electrodes, and from each of the output electrodes an output can be obtained according to the position of incident light on the light receiving surface, and the above-mentioned object to be detected is placed on the light receiving surface of the semiconductor device detection element. A position detection device characterized in that the position detection device is arranged such that a light-shielded portion and a light-unshielded portion are projected, and the position of the detected object is detected based on the output from each of the output electrodes.