JPH02287103A - Position detector for actuator - Google Patents

Abstract

PURPOSE:To prevent a set range from being affected by temperature variation by providing a temperature compensating means at the amplification part for the signal of a sensor which detects the position of the actuator. CONSTITUTION:A sensor part 1 consists of an MR element and outputs a volt age corresponding to whether a magnet packaged on the actuator moves to or away from the sensor part to display the position of the actuator. The ampli fication part 2 amplifies the output, and sends a specific output signal when the output exceeds a specific value to make red and green LEDs of the tempera ture compensation part 3 radiate corresponding to the specific range. A tempera ture compensation part 3 is connected to the amplification part 2. Then if the sensor output varies with the ambient temperature, the compensation part 3 functions to suppress the variation and equalize the low-temperature and high- temperature sensor characteristics to those at reference temperature, so the set range is not affected by the temperature variation.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a technology for detecting the position of an actuator, particularly,
The present invention relates to a technique that can be effectively used to display the position of an actuator in two colors.

[Conventional technology]

In order to accurately operate the control system that adjusts fluid pressure,
Accurately knowing the position of the actuator of a hydraulically operated device is extremely important. To this end, position detection has conventionally been performed using a position detection circuit incorporating a magnetic sensor such as a reed switch or a magnetoresistive element (hereinafter simply referred to as an MR element).

For example, a position detection circuit using an MR element is configured as follows.

That is, the output of a differential amplifier that amplifies the electrical signal detected by the MR element is compared with a preset reference voltage, and the light emitting diode (hereinafter simply referred to as L) is
The device is configured to light up an LED (referred to as an ED) and also drive an output circuit for generating a signal to be sent to a control device or the like.

A detection signal is obtained as the magnet attached to the actuator approaches or moves away from the MR element, and the LED lights up when a voltage higher than a certain level is generated in the MR element. This lighting is performed only when the area is within a preset operating range (a predetermined movement range of the actuator), and there is a one-color display method in which only one LED lights up, and two LEDs such as red and green.
There is a two-color display system that lights up selectively depending on the position of the actuator. Among these, the two-color display method has the advantage of being able to display the optimal setting position.

In the case of the two-color display method, as shown in Figure 7, a setting range (for example, 5 mm) for lighting the green LED is secured in the middle of the actuator's operation range (for example, 13-). A margin (for example, 4 mm) for lighting the red LED is secured on both sides.

In FIG. 7, when the actuator moves from one side and enters a margin within the operating range, the red LED lights up, and as soon as it passes through this margin and enters the set range, the green LED lights up.

In this way, the two-color display method can display the movement of the actuator in stages, so it is easy to install by checking the two-color display when setting and setting with the green LED lit. I can do it.

[Problem to be solved by the invention]

However, in the actuator position detection device using the MR element as described above, the characteristics of the MR element change depending on the temperature of the atmosphere in which it is used, and this causes a problem in that the detection position shifts.

In other words, even if each range is set under the standard temperature as shown in Figure 7, the set range will change from 5 to 6.5 m at 0°C as shown in Figure 8 (a). Changed to 1.5
On the other hand, at 60°C, as shown in Figure 8, etc., the setting range is 1.5 In
I11 becomes shorter. In other words, the setting range changes by three strokes between 0°C and 60°C. Therefore, if the setting work is performed at one end of the temperature range, the green LE will be displayed at the other end of the temperature range.
There will be cases where the red LED lights up when D should light up. As a result, even if the workpiece using the position detection device is normal, there is a possibility that an abnormal output may be generated.

Therefore, the setting range display, which is a feature of the two-color display method, cannot be utilized, and there may be cases where settings must be made in accordance with the contents of the one-color display method.

The purpose of the present invention is to eliminate the change in the setting range due to temperature.
An object of the present invention is to provide a position detection device for an actuator that can maintain a two-color display function.

Another object of the present invention is to provide an actuator position detection device that can eliminate changes in the setting range due to power fluctuations.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Means to solve the problem]

A brief overview of typical inventions disclosed in this application is as follows.

That is, there is a sensor section that detects the position of the actuator as two detection signals with different peak generation times, and a sensor section that amplifies each of the detection signals from the sensor section and generates an output signal when the amplified output exceeds a threshold. and an output/display means for lighting two light emitting elements in accordance with a set range and a margin range based on two output signals of the amplifying part, wherein the sensor part or the The amplifier section is provided with temperature compensation means.

[Effect]

According to the above means, while the output of the sensor section fluctuates up and down in response to changes in the ambient temperature, the temperature compensation means functions to suppress the up and down fluctuations, and standardizes the sensor characteristics in the low temperature range and high temperature range. Equivalent to temperature. As a result, it becomes possible to eliminate changes in the setting range due to temperature.

[Embodiment 1] FIG. 1 is a block diagram showing the overall configuration of an actuator position detection device according to an embodiment of the present invention, and FIG. 2 is a circuit diagram showing its detailed configuration.

In FIG. 1, the sensor section 1 is constructed using the above-described MR element, and outputs a voltage corresponding to the approach and separation of the magnet attached to the actuator. An amplifier section 2 is connected to the sensor section 1, and amplifies the output signal of the sensor section 1 to a predetermined level. The amplification section 2 includes an amplifier that amplifies the output signal of the sensor section 1, and a comparator that compares the detection signal voltage with a reference voltage.

A temperature compensator 3 is connected to the amplification B2, which functions to cancel output fluctuations due to temperature of the sensor unit 1. Furthermore, the amplifying section 2 includes a display section 4 consisting of a red LED and a green LED that selectively light up according to the comparison result of a built-in comparator, and an output section 5 for sending out the comparison result of the comparator to the outside. are connected to each other. This output section 5 outputs two systems of output signals as described later.

The power supply section 6 supplies power to each of the above sections. This power supply section 6 is configured to include a voltage stabilization circuit, and uses a circuit such as a voltage stabilization IC that outputs an extremely low voltage even if the power supply input fluctuates.

Next, details of each part will be explained with reference to FIG. 2.

The sensor section 1 includes four MR elements 1a, lb, 1c, and ld.
It is constructed by assembling them in a bridge type, with each intermediate connection point serving as an output section.

The amplification unit 2 includes operational amplifiers 201 and 202 that individually amplify each output of the sensor unit 1, a comparator 203 that compares the output voltage of the operational amplifier 201 with a reference voltage, and a comparator 203 that compares the output voltage of the operational amplifier 202 with the reference voltage. Comparator 204
It is mainly composed of.

In the figure, 205 to 208 are voltage setting resistors 209 and 210 applied to the non-inverting terminals of operational amplifiers 201 and 202.
are the feedback resistors of operational amplifiers 201 and 202, 211~
214 is a human resistor for determining the value of the feedback resistor of the operational amplifiers 201 and 202. Also, 215-2
18 is a resistor for setting the reference voltage applied to the inverting terminals of the operational amplifiers 203 and 2040. 219 and 220 are resistors for determining the comparison level in combination with resistors 221 and 222 inserted between the input and output of the operational amplifiers 203 and 204.

The temperature compensator 3 includes a voltage follower circuit using an operational amplifier 31, resistors 33 and 34 connected to both ends, and a DC power supply V.
It mainly consists of a temperature compensation diode 32 connected between CC and ground and whose cathode side is connected to the non-inverting terminal of an operational amplifier 31. And op amp 31
The output terminal of is connected to the operational amplifier 2 via resistors 35 and 36.
It is connected to each non-inverting terminal of 01 and 202.

The display section 4 includes a green LED 41, a red LED 42, and a resistor 43 that regulates the current flowing through each LED.

The output section 5 includes an OR circuit 51 that takes the output voltages of the comparators 203 and 204 as input and takes a logical sum, an AND circuit 52 that takes the output voltages of the comparators 203 and 204 as input and takes a logical product, and an output of the OR circuit 51. An exclusive OR (hereinafter referred to as
Each of the circuits 53 (referred to as EX-OR) constitutes a circuit for driving the display section 4.

Furthermore, resistors 54a and 54b for dividing the output voltage of the OR circuit 51, a transistor 55 with a common emitter configuration whose base bias is the divided voltage output, resistors 56a and 56b for dividing the output voltage of the EX-OR circuit 53, and the voltage dividing thereof. Output signal 1 and output signal 2 are generated by each of the transistors 57 having a common emitter configuration and using the output as a base bias.

The power supply unit 6 includes a capacitor 61 that smoothes a DC voltage provided by a rectifier circuit or a stabilization circuit (not shown), a voltage stabilization circuit 62 that stabilizes and outputs the applied DC voltage,
It consists of a capacitor 63 connected to the output terminal of this circuit 62.

The output voltage Vcc of this power supply section 6 is the power supply line (V
ec).

Next, the operation of the embodiment with the above configuration will be explained in the third section.
This will be explained with reference to the figures.

Here, an air cylinder device including a cylinder and a piston will be described as an example of an actuator. In this case, the position detection device 10 according to the present invention is mounted on a cylinder 11 at a detection position by a belt 12 as shown in FIG. installed.

The piston rod 13 moves, and the MR element 1 of the sensor section l
When approaching a -1d, these resistance values change,
A voltage corresponding to the change is output as a detection signal from each intermediate connection point as shown in FIG.

Each output signal is amplified to a predetermined level by operational amplifiers 201 and 202.

At this time, as explained in FIG. 8, the MR elements 1a to 1
The characteristics of d change depending on the ambient temperature. in this case,
When the ambient temperature increases, the output voltage of the sensor section 1 decreases. Conversely, when the ambient temperature decreases, the output voltage of the sensor section 1 increases. Therefore, in the present invention, in order to compensate for the decreased sensor output voltage, the temperature compensation unit 3 increases (or decreases) the voltage at the non-inverting terminals of the operational amplifiers 201 and 202 of the amplifier unit 2 to eliminate the influence of the ambient temperature. ing.

Here, the temperature compensator 3 operates as follows.

That is, when the ambient temperature rises, the voltage drop across the diode 32 becomes smaller, and therefore the terminal voltage of the resistor 34 becomes larger. This voltage value is taken out as it is by the operational amplifier 31, and is applied to the non-inverting terminals of the operational amplifiers 201 and 202 via the resistors 35 and 36 as a reference voltage Vr.
It is applied as llfl+Vr*r2. On the other hand, when the ambient temperature decreases, the terminal voltage of the resistor 34 decreases, and the sensor output is compensated to decrease.

It should be noted that the detection signals of the two sensor units 10 are not output with the same peak, but with a deviation. Therefore, the output voltages of the operational amplifiers 201 and 202 are also outputted with a time lag as shown in FIG.

The output voltages from the operational amplifiers 201 and 202 are compared by comparators 203 and 204 at the next stage with a reference voltage Vco+apl+Vco*px obtained by dividing VCC. Comparators 203 and 204 have a reference voltage V
An output signal is generated only when the non-inverting terminal input exceeds co□l + VCOIIP2. The output timing of the comparator 204 is later than that of the comparator 203, and this time difference becomes the margin range explained in FIG. 7.

The outputs of the comparators 203 and 204 are ORed by the OR circuit 51, and when either output is at the "H" level, the OR circuit 51 outputs an "H'" level voltage. After voltage division, this output voltage is applied to the base of the transistor 55, and remains on while the voltage is applied to the base. As is clear from FIG. 3, the output signal of this transistor 55 corresponds to the operating range.

Further, the AND circuit 52 to which each output of the comparators 203 and 204 is input has an output of "H" level only when both surface inputs are "H" level, and the green LED 41 connected as a load lights up. do.

This lighting continues until the output of the AND circuit 52 becomes "L" level.

Further, in the EX-OR circuit 53 to which each output of the OR circuit 51 and the AND circuit 52 is manually input, the output of the OR circuit 51 is at the "H" level, and the output of the AND circuit 52 is "H" level.
The EX-OR circuit 53 outputs a signal corresponding to the voltage signal at a timing excluding a certain part of the H'' level. Then, the EX-OR circuit 53 lights up the red LED 42 connected as a load.

The lighting period of this red LED 42 becomes a margin range.

Furthermore, the output voltage of the EX-OR circuits 5 and 3 is controlled by the resistor 56a.
and 56b, and applied to the base of the transistor 57. Transistor 57 remains on while voltage is applied to its base.

The output signal 2 output from this transistor 57 is used, for example, as prediction information. In today's production factories, there is a demand to avoid line stoppages as much as possible in order to increase operating rates. On the other hand, with the two-color display method, it is possible to obtain output signal 2, and from this signal, it is possible to know at an early stage whether the cylinder rod screw is loosened or the cylinder stroke is off due to a malfunction of the workpiece, and take necessary measures. be able to.

According to the above embodiment, by providing the temperature compensation section 3, the temperature change rate of the sensor section 1 can be reduced from 1/9 to 1/1, for example.
I was able to reduce it to 6. Furthermore, by stabilizing the power supply section 6, the voltage change rate could be reduced to 1/15. As a result, it is possible to prevent fluctuations in the setting range, which has been a problem in the past, and it has become possible to fully utilize the functions of the two-color display system.

[Embodiment 2] FIG. 5 is a block diagram showing another embodiment of the actuator position detection device according to the present invention, and FIG. 6 is a circuit diagram showing its details.

As shown in FIG. 5, in the second embodiment, temperature compensation is performed on the sensor section 1, whereas in the first embodiment, the temperature compensation is performed on the amplification section 2.

For this purpose, a temperature compensation section 7 is connected to the sensor section 1.

The temperature compensator 7 includes a transistor 71 as shown in FIG.
, a resistor R1, and a resistor R2. The transistor 71 uses an NPN type, and its collector is connected to the power supply V.
Ce, and its emitter is connected to the common connection portion of the MR element 1a and the IC.

Further, the resistors R3 and R2 are connected in series and inserted between the collector and the emitter, and the intermediate connection point is the transistor 7.
Connected to 10 base.

In this circuit, the base-to-base voltage V of the transistor 71 changes depending on the ambient temperature, and this Vll! This method utilizes the fact that the corephtal emitter voltage V changes due to changes in V. VB is expressed by the following equation, where T is the temperature.

Vm = Vl): (T) (1+R+ /Rt)
When the ambient temperature rises, (1) decreases, and the voltage applied to each MR element of the MR element 1 increases.

As a result, the sensor output, which has decreased due to temperature rise,
It is compensated to be the same as under the reference temperature. Conversely, if the ambient temperature drops, each MR
The voltage applied to the element is lowered, and the sensor output is also temperature compensated. As a result, similar to the above embodiment, the conventional problems are solved.

Although the invention made by the present invention has been specifically explained based on Examples above, it goes without saying that the present invention is not limited to the above-mentioned Examples and can be modified in various ways without departing from the gist thereof. .

〔Effect of the invention〕

Since the present invention is configured as described above, the following description will be made.
It has the effect of

In the actuator position detection device according to claim 1,
A sensor section that detects the position of the actuator as two detection signals with different peak generation times, and an amplification section that amplifies each of the detection signals from the sensor section and generates an output signal when the amplified output exceeds a threshold value. and an output/display means for lighting two light emitting elements according to a set range and a margin range based on two output signals of the amplifying section, wherein the sensor section or the amplifying section Since the temperature compensation means is provided, the setting range is not affected by temperature changes. As a result, the position detection device can be set reliably, and the reliability of the prediction output is also increased.

Further, in the actuator position detection device of claim 2, in addition to the configuration of claim 1, voltage stabilization means for stabilizing the power supply of at least the sensor section and the amplification section is provided, so that the power supply voltage increases as the temperature changes. It becomes possible to prevent changes in the setting range due to fluctuations.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the overall configuration of an actuator position detection device that is an embodiment of the present invention, FIG. 2 is a circuit diagram showing the detailed configuration of the position detection device shown in FIG. 1, and FIG.
Timing chart showing the operation of each part of the circuit shown in the figure, No. 4
The figure is a front view showing the mounting situation of the actuator position detection device according to the present invention, FIG. 5 is a block diagram showing the actuator position detection device according to another embodiment of the present invention, and FIG. A circuit diagram showing the detailed configuration of the position detection device,
Fig. 7 is an explanatory diagram showing the setting range and margin range setting for the reference temperature of the position detection device, and Figs. 8 (a) and (b) show the setting range and margin range setting at 0°C and 60°C. It is an explanatory diagram. 1a-1d...MR element, 2......Amplification section, 3.7...Temperature compensation section, 4...Display section, 5...... ...Output section, 6...Power supply section, 41...Green LED. 42... Red LED. Figure 6 Figure 5

Claims (1)

[Claims] 1. The position of the actuator is different from the peak generation point 2.
a sensor section that detects one detection signal; an amplification section that amplifies each of the detection signals from the sensor section and generates an output signal when the amplified output exceeds a threshold; and two output signals of the amplification section. A position detection device comprising an output/display means for lighting two light emitting elements in accordance with a set range and a margin range based on the above, wherein the sensor section or the amplification section is provided with a temperature compensation means. Characteristic position detection device for actuators. 2. The actuator position detection device according to claim 1, further comprising voltage stabilizing means for stabilizing the power supply of at least the sensor section and the amplifier section.