JPH02298801A - Detection device of position - Google Patents

Abstract

PURPOSE:To enable detection of a specified position within the motion width of a piston even with one magnetic sensor and one pilot lamp by varying the luminance of the pilot lamp in accordance with an output of a detection signal of the magnetic sensor. CONSTITUTION:A magnetic sensor 11 outputs a detection signal S1 in accordance with the intensity of the magnetic field of a permanent magnet fitted to a piston and an output signal S2 amplified by an amplifier 12 is inputted to a comparator 15. In the comparator 15, the signal S2 is compared with a threshold value signal V1 set by voltage dividing resistor 13 and 14, and a detection signal S3 is outputted when the signal S2 is larger. A transistor 17 conducts on the basis of this detection signal S3 and a light-emitting diode 18 lights by receiving a drive current from the amplifier 12. The luminance of the diode 18 turns dark as a piston approaches a motion width, and it becomes maximum in the central part. Thus, a specified position in the motion width can be detected even when the number of components is decreased.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a position detection bag for detecting the stroke position of a piston in a fluid pressure cylinder! Regarding.

[Conventional technology]

BACKGROUND ART Conventionally, a position detection device for detecting the stroke position of a piston has been attached to a fluid pressure cylinder such as a hydraulic cylinder or a pneumatic cylinder.

In conventional position detection devices, a magnetic sensor attached to the outer circumferential surface of the cylinder tube outputs a detection signal according to the strength of the magnetic field due to the magnetic field of a permanent magnet attached to the piston, and this detection signal remains constant. In addition to outputting a detection signal when the value exceeds the darkness value of It is configured.

The detection signal has a certain width (operation width) with respect to the distance in the stroke direction of the piston, and while the piston is within this operation width, the detection signal is output and the indicator light is also lit. . Therefore, even if the indicator light is on, it is impossible to know where the piston is within its operating range.

For this purpose, two magnetic sensors with different operating ranges and two indicator lights are provided, one of which lights up when the piston enters the operating range, and the other one lights up when the piston enters the operating range. A position detection device has been proposed in which the indicator light is turned on when the piston is located at the center of its operating width.

[Problem to be solved by the invention]

However, the above-mentioned conventional position detection device requires two magnetic sensors and two indicator lights, which increases the number of parts and complicates the circuit, resulting in an increase in the manufacturing cost of the position detection device.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, it is an object of the present invention to provide a position detection device that can detect a specific position within the operating range even if there is only one magnetic sensor and one indicator light.

[Means to solve the problem]

In order to solve the above-mentioned problems, the present invention provides a position detection device for detecting the position of a moving object using the magnetic field of a permanent magnet provided on the moving object. a magnetic sensor that outputs a detection signal according to the strength of the detection signal, a comparison unit that outputs a detection signal when the detection signal is equal to or higher than a certain darkness value, and a lighting unit that lights up an indicator light based on the detection signal. and the luminance of the indicator lamp is changed in accordance with the detection signal.

(Function) A magnetic sensor detects the magnetic field of a permanent magnet attached to a moving object and outputs a detection signal corresponding to the strength of the magnetic field.

The comparison means compares the detection signal from the magnetic sensor with the darkness value, and outputs a detection signal when the detection signal is greater than or equal to the darkness value.

The lighting means lights up the indicator light in response to the detection signal.

The brightness of the indicator light changes depending on the detection signal.

〔Example〕

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

FIG. 1 is an electrical circuit diagram of a position detection device l according to the present invention.

The position detection device 21 includes a magnetic sensor 11 that outputs a detection signal St according to the strength of a magnetic field, an amplifier 12 that amplifies the detection signal S1, an output signal S2 of the amplifier 12, and a voltage dividing resistor 13.
A comparator 15 which compares the dark value voltage v1 set by 14 and outputs a detection signal S3 when the output signal S2 is large; transistors 16 and 17 which conduct when the base input is on; transistors 16 and 17 which conduct when the transistor 17 conducts It is composed of a light emitting diode 18 and the like that lights up.

Each of these parts is housed in a suitable housing, the magnetic sensor 11 is placed in the center of the housing, and the light emitting diode 18 is mounted so that its lighting can be easily confirmed from the outside.

Next, the operation of the position detection device 1 configured as described above will be explained with reference to FIG. 2 as well.

FIG. 2 shows that the piston 21 to which the permanent magnet 22 is attached is positioned in the left-right direction (arrow M
FIG. 3 is a diagram showing the state of signals of each part when moving in one direction.

When the piston 21 is at the position facing the position detection device 1, that is, at the center position P1 of the position detection device 1, the output signal S2 (detection signal Sl) is maximum, and the center position PI
The output signal S2 (detection signal Sl) decreases as it moves from left to right.

The piston 21 has a movement width B centered on the median value 1tP1.
2, the output signal S2 is within the range of threshold voltage v
Since the detection signal S3 is larger than 1, the comparator 15 detects the detection signal S3.
Output. This detection signal S3 is sent via the transistor 16 to an external control device as a position detection signal S4 of the piston 21.

On the other hand, the transistor 17 is made conductive by the detection signal S3, and the light emitting diode 18 is turned on by being supplied with a drive current from the amplifier 12.

The brightness of the light emitting diode 18 is the median value W of the piston 21.
As it approaches P1, it increases in accordance with the output signal S2,
When the piston 21 enters the range of the operating width B1, which is the center of the operating width B2, it becomes saturated and remains approximately constant. That is, when the piston 21 is within the range of the operating width Bl, the brightness of the light emitting diode 18 becomes maximum.

When the piston 21 is outside the operating width B2, the detection signal S3 is not output, so the light emitting diode 18 does not light up.

Therefore, when the light emitting diode 18 is dimly lit, the piston 21 is within the range of the operating width B2 of the position detection device 1, and the detection signal S4 is output, but not at the center of the operating width B2. When the light emitting diode 18 is brightly lit at maximum brightness, the piston 21 is within the range of the operating width Bl of the position detection device 1, the detection signal S4 is output, and the piston 21 is at the center of the operating width B2, Detection signal S
4 is confirmed to be stable.

According to the embodiment described above, there is only one magnetic sensor 11 and only one light emitting diode 18, but the piston 21
It is possible to know whether or not the position is within the motion width Bl of a specific position within the motion width B2. Therefore, the position detection bag 21
The number of parts required is small, the circuit becomes simple, and an increase in the manufacturing cost of the position detection device 1 is prevented. Since there is only one light emitting diode I8, and only the luminance (brightness) is checked, confirmation is easy. Also, power consumption is reduced. By varying the threshold voltage Vl or the gain of the amplifier 12, the operating widths Bl and B2 can be easily variably adjusted. Further, unlike the case where a plurality of magnetic sensors are used, there is no variation in the position of the operating width B1 with respect to the operating width B2 due to variations in the characteristics of the plurality of magnetic sensors, and adjustment is easy.

In the above embodiment, the driving current of the light emitting diode 18 may be set so that the brightness does not become saturated, and the brightness may be maximized when the piston 21 is at the center position Pl.

In the above embodiment, instead of the light emitting diode 18,
A neon lamp, a light bulb, or the like may be used, and the circuit configuration of the position detecting device 1 may be of various types other than those described above.

For example, the circuit of the position detection device 1 can be configured to change the brightness of the light emitting diode 18 (indicator light) as shown in FIGS. 3(a) and 3(b).

That is, in the case of FIG. 3(a), the transistor 17
The circuit constants are set so that when the light emitting diode 18 becomes conductive, the brightness gradually increases from the lowest brightness, and
A second comparator is provided that outputs a detection signal when the output signal S2 is larger than a dark value voltage that is larger than the threshold voltage Vl, and a constant drive current is supplied to the light emitting diode 18 based on the detection signal of this second comparator. However, when the piston 21 is within the operating width B2, the light emitting diode 18 is turned on at maximum brightness.

In the case of FIG. 3(b), a predetermined drive current is supplied to the light emitting diode 18 when the piston 21 is within the operating width B2 or within the operating width Bl. Then, the brightness of the light emitting diode 18 is changed stepwise.

〔Effect of the invention〕

According to the present invention, the magnetic sensor and the indicator light each have one
However, it is possible to know whether it is at a specific position within the operating range. Therefore, the number of parts of the position detection device can be reduced, the circuit can be simplified, and an increase in the manufacturing cost of the position detection device can be prevented.

[Brief explanation of drawings]

FIG. 1 is an electric circuit diagram of a position detection device according to the present invention, and FIG.
The figure shows the signal status of each part, Figure 3 (a) and (b).
) is a diagram showing another example of the brightness change in FIG. 2. l...Position detection device, 11...Magnetic sensor, 15
...combare') (comparison t2 means), 17...
Transistor (lighting means), 1B... Light emitting diode (indicator light), 21... Piston (moving object), 22.
...Permanent magnet, Sl...Detection signal, S2...Output signal (detection signal), S3...Detection signal, Vl...Dark value voltage (dark value).

Claims (1)

[Claims] (1) A position detection device for detecting the position of a moving object using the magnetic field of a permanent magnet provided on the moving object, which detects the magnetic field of the permanent magnet and generates a detection signal according to the strength of the magnetic field. a magnetic sensor that outputs a magnetic sensor, a comparison unit that outputs a detection signal when the detection signal is equal to or higher than a certain threshold, and a lighting unit that lights up an indicator light in response to the detection signal, the display according to the detection signal. A position detection device characterized by changing the brightness of a light.