JPH07104148B2 - Position detector - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a detector for detecting the position of a switching target in a device that automatically switches a three-way cock, a switching valve, or the like.

(Prior art) For example, by automatically switching the three-way cock, 9
When trying to stop at the three-point position of 0 degree, it is not enough to detect that the three-way cock is in one of those stop positions, and it is possible that the three-way cock is in the intermediate position of the three points. Detection will also be necessary. That is, if only the stop position is detected, it is not possible to determine which of the front and rear states is overshooted when the detection point is overshot.

Some position detectors use limit switches. However, the limit switch is not suitable for downsizing, and it is difficult to detect the intermediate state between the stop positions.

A position detector using a cam mechanism is also often used. However, a cam mechanism with sufficient torque is not suitable for miniaturization.

It is common to use a photo interrupter for the position detector.

(Problems to be Solved by the Invention) When detecting the position of an object using a photo interrupter, it is common to detect whether or not the detection end of the object has passed through the photo interrupter. . Therefore, when trying to stop the object at a predetermined position,
It can only detect at that stop position. When trying to detect an intermediate state in which the detection end is between the stop positions, there are problems that the number of photo interrupters increases and the shape of the detection target becomes complicated.

INDUSTRIAL APPLICABILITY The present invention is suitable for downsizing so that not only the stop position state of the target object but also the intermediate position state between the stop positions can be detected so that the switching operation of the target object in the automatic switching device can be performed accurately. An object of the present invention is to provide a position detector that can be realized with a simple structure.

(Means for Solving the Problems) Referring to FIG. 1 showing an embodiment, in the position detector of the present invention, a plurality of stop positions arranged at equal angular intervals around the rotation axis are provided. A rotating plate (2) attached to the rotation axis of the object to be detected, and the object on the circumference of the periphery of the rotating plate (2) where the optical path is blocked by the rotating plate (2). Multiple photo interrupters (PI _{1 to} PI ₄ ) arranged at positions bisected by the stop position of
And provided on the periphery of the rotary plate (2) so that only the light of two photo interrupters of the plurality of photo interrupters (PI _{1 to} PI ₄ ) is transmitted at the stop position of the object and the other positions Is provided with a notch (4) that transmits only the light of one photo interrupter, and is configured to detect the position of the detection target by the combination of the detection signals of the photo interrupters (PI _{1 to} PI ₄ ).

(Embodiment) FIG. 1 shows an embodiment.

PI _{1 to} PI ₄ are photo interrupters, which are provided at intervals of 90 degrees on the circumference. a to d are each photo interrupter PI
_It indicates the optical axis position of _{1 to} PI ₄ .

Reference numeral 2 denotes a rotary plate as a detection target, which rotates together with a target (not shown) such as a cock in the switching device.
The center of rotation of the rotary plate 2 and the center of the circle in which the photo interrupters PI _{1 to} PI ₄ are arranged coincide. The peripheral portion of the rotary plate 2 crosses the optical axes a to d of the photo interrupters PI _{1 to} PI ₄ .

The rotary plate 2 is provided with a U-shaped notch 4 at one position on the peripheral portion. Both ends 6 and 8 of the notch 4 are detection ends. The distance L between both ends 6 and 8 of the notch 4 is set to be slightly longer than the distance l between the optical axes of the adjacent photo interrupters.

Assuming that the center position of the notch 4 is the position of the rotary plate 2, that is, the position of the object to be switched, four points A, C, E, and G are stop positions in the figure, and positions B and D between these stop positions are shown. , F, H are intermediate positions. Distance L between both ends 6 and 8 of notch 4
If is set to be much larger than the distance l between the optical axes of the adjacent photo interrupters, the positioning accuracy at the stop position is reduced.

The photo interrupters PI _{1 to} PI ₄ are turned on when their optical axes a to d are in the notches 4 of the rotary plate 2, and are turned off when covered by the rotary plate 2. When the output of the photo interrupter in the ON state is represented by H and the output of the photo interrupter in the OFF state is represented by L, the photo interrupter PI is determined depending on which of the positions A to H in FIG.
The outputs of _{1 to} PI ₄ are shown in the detection output column in the table below.

In this way, by combining the outputs of the _four photo interrupters PI _{1 to} PI ₄ , it is possible to identify which position of the rotary plate 2 is from A to H.

Next, an example in which the embodiment of FIG. 1 is applied to an automatic switching device using a three-way cock and switching control is performed so that the handle of the three-way cock is stopped at three points in FIGS. C, E, and G will be described.
Position A should not be taken. The position of the handle is assumed to coincide with the center position of the cutout 4 of the rotary plate 2.

FIG. 2 shows an example of a control circuit used in that case.

In FIG. 2, 10 is a decoder, which has four inputs having the detection signals of the _four photo interrupters PI _{1 to} PI ₄ as input signals and six outputs Ohab, Oc, Od, Oe, Of, Og. I have _One of the outputs becomes H (high level) depending on the combination of the _four inputs PI _{1 to} PI ₄ . Here, the subscripts of the output symbols correspond to the positions in FIG. Ie output for example
Oc indicates that the handle position of the three-way cock is at point C in FIG.

Reference numeral 12 is a comparison circuit, which outputs the output of the decoder 10 to three OR circuits.
The two-bit control inputs I ₁ and I ₂ are input via the inverter circuits IN ₁ and IN ₂ as well as being input via OR _{1 to} OR ₃ and compared. As the control input I _1, I ₂ are shown in the control input column in the table above, the I ₁ L (low level) when it is desired to stop the handle of the three-way cock in the position C, the I ₂ H (high level ), I ₁ is H and I ₂ is L to stop at the E position, and I ₁ and I ₂ are both L to stop at the G position. Control input inverted by inverter circuits IN ₁ and IN ₂
I ₁ and I ₂ are output via the NOR circuit NOR ₃ to the output NOR circuit N of the comparison circuit 12.
Input to OR ₁ and NOR ₂ respectively.

The output Do of the NOR circuit NOR ₁ is a signal for rotating the rotating plate 2 clockwise in FIG. 1, and the output D ₁ of the NOR circuit NOR ₂ is rotating the rotating plate 2 counterclockwise in FIG. Is a signal for. Output Do, D ₁ of the comparison circuit 12, by comparing the photo-interrupter PI ₁ ~PI input signal and the control input I ₁ of _4, I _2, three-way cock handle is set at the control input I _1, I ₂ Do or D ₁ becomes H depending on whether it is before or after the stop position. Then, when the handle of the three-way cock coincides with the set stop position, both Do and D ₁ become L, and the drive of the handle of the three-way cock is stopped.

The outputs D ₂ and D ₃ represent position outputs. Decoder 10
The outputs Oc, Oe and Og of are combined and displayed by the OR circuits OR ₄ and OR ₅ .

The operation of the control circuit shown in FIG. 2 will be described.

Now, assume that the handle of the three-way cock is in the stop position E in FIG. At this time, since the outputs of the photo interrupters PI ₂ and PI ₃ are H and the others are L, only the output Oe of the decoder 10 is H. The position output D ₂ is L and D ₃ is H.

Next, in order to switch the handle of the three-way cock to the C position, the control input I _{1 is set} to L and I _{2 is set} to H. As a result, in the comparison circuit 12, the output D ₁ becomes H, and the rotary plate 2 starts rotating counterclockwise together with the handle of the three-way cock. At the same time, the output Od of the decoder 10 becomes H, and the position outputs D ₂ and D ₃ both change to L. Eventually, the handle of the three-way cock is C
When the position is reached, the output Oc of the decoder 10 becomes H, the output D ₁ of the comparison circuit 12 becomes L, and the rotation plate 2 stops the rotation of the handle of the three-way cock. Then, in the position output, D ₂ becomes H and D ₃ becomes L.

If the rotary plate 2 uses the inertia of the handle of the three-way cock and the motor and the handle of the three-way cock passes through the C position and enters the B position, the output Oh of the decoder 10
Since ab becomes H and the output Do of the comparison circuit 12 becomes H, the rotary plate 2 will be rotated clockwise together with the handle of the three-way cock in the future.

In this way, the handle of the three-way cock has control inputs I ₁ , I
Switch to the stop position set in ₂ .

When both control inputs I ₁ and I ₂ are H, the output NOR circuit
Since the outputs Do and D ₁ of NOR ₁ and NOR ₂ are both L, the rotating plate 2
And the handle of the three-way cock stops at that position.

In the embodiment shown in FIG. 1, the stop position is in units of 90 degrees,
An arbitrary angle can be detected by changing the number and intervals of the photo interrupters and the size of the notch.

As the detecting element, the photo interrupter is used in the embodiment, but other detecting elements may be used.

Further, although the embodiment detects the rotation angle, the present invention can also be applied as a linear movement position detector.

(Effects of the Invention) According to the position detector of the present invention, the following effects can be achieved.

(1) The minimum number of detection elements can detect not only the stop position state of the detection target object but also the intermediate position state thereof.

(2) Suitable for miniaturization.

(3) The simple structure leads to cost reduction.

(4) Detection can be reliably performed.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of the present invention, and FIG. 2 is a circuit diagram showing a control circuit for controlling a three-way cock etc. using the same embodiment. PI _{1 to} PI ₄ ...... Photo interrupter as a detection element, 2 ...... Rotating plate as an object to be detected, 4 ...... Notch, 6, 8 ...... Both ends of notch as detection end.

Claims (1)

[Claims] 1. A rotary plate attached to the rotary shaft of a detection object having a plurality of stop positions arranged at equal angular intervals around the rotary shaft, and an optical path by the rotary plate at the periphery of the rotary plate. A plurality of photointerrupters arranged in a position bisected by the stop position of the object on the circumference of the position where the object is stopped; A cutout that allows only the light of two photointerrupters of the plurality of photointerrupters to pass through at a position and allows only the light of one photointerrupter to pass through at other positions, and a detection signal of the photointerrupter is provided. A position detector characterized by detecting the position of a detection target by a combination.