JP2008020032A - Position detector for fluid pressure cylinder - Google Patents

Abstract

Even if a position detection device is attached to a fluid pressure cylinder so that a lead wire drawing side is on a piston side or a head side, stable position detection can be performed.
A position detection device (10) includes a circuit board (20) vertically arranged with respect to a magnet (16) provided on a piston (12) in a state of being attached to a fluid pressure cylinder (11), and one on both surfaces of the circuit board (20). Two magnetic sensors 21 and 22 are provided in a state where they are shifted in the moving direction of the piston 12 and a part of the operation range is overlapped. The magnetic sensors 21 and 22 compare the output voltage of the magnetoresistive element showing the resistance value corresponding to the strength of the magnetic field from the magnet 16 with the reference voltage and the comparator and output the comparison result. The position detection device 10 includes a light emitting diode that emits light when one of the two magnetic sensors 21 and 22 is in a detection state, and a light emitting diode that emits light when both of the two magnetic sensors 21 and 22 are in a detection state.
[Selection] Figure 1

Description

  The present invention relates to a position detecting device for a fluid pressure cylinder, and more particularly to a position detecting device for a fluid pressure cylinder used when detecting a piston position of a fluid pressure cylinder using an MR element (magnetoresistance element). .

  Conventionally, a fluid pressure cylinder using fluid pressure, such as an air cylinder, is known. When this type of fluid pressure cylinder is used, it is usually necessary to detect the position of the piston in some stroke by some means. As a means for realizing such piston position detection, a fluid pressure cylinder position detection device (hereinafter simply referred to as position detection) provided with a magnetic sensor having an MR element (magnetoresistance element) as a detection element. Is sometimes referred to as a device) (see, for example, Patent Document 1).

  The position detection device disclosed in Patent Document 1 includes two magnetic sensors provided apart from each other by a predetermined distance along the axial direction of the cylinder body, and detects the magnetism of a magnet mounted on the piston of the cylinder. The position of is detected. As shown in FIGS. 5A to 5D, the two magnetic sensors 51 and 52 detect the magnetic field 54 of the magnet 53 as only one of them detects the movement of the magnet 53 (FIG. 5B, (D) state) and a positional relationship in which both are detected simultaneously (the state of FIG. 5C). The first light emitting diode is turned on when one of the magnetic sensors 51 or 52 is detected, and the first and second light emitting diodes are turned on when both the magnetic sensors 51 and 52 are detected. It has become. The range in which both the first light emitting diode and the second light emitting diode are lit is the optimum range of the piston, and the range in which only one of the light emitting diodes is lit is the allowable range.

  Two-color display position that processes the output signals of the two magnetic sensors so that the red light-emitting diode lights up when the piston is within the allowable range, and the green light-emitting diode lights up when the piston is within the optimum range. The detection device is manufactured and sold.

  In consideration of the ease of manufacturing the position detection device and the manufacturing cost, two magnetic sensors are arranged side by side in the moving direction of the magnet in one chip, and a plurality of logic circuits for processing the output signals of both magnetic sensors are provided. There has also been proposed a position detection device that is formed on one chip, both chips are mounted on a substrate, and embedded in a synthetic resin case (see, for example, Patent Document 2).

These position detection devices have a configuration in which two magnetic sensors are both attached to one side of the substrate. There are also ICs in which the magnetic sensor and the comparator for processing the output signal are integrated into a single chip. Even when the IC chip is used, the position detection device is in a state where two magnetic sensors are arranged on one side of the substrate. Consists of.
Japanese Utility Model Publication No. 6-12484 JP-A-11-311214

  In general, the position detection device can be moved along the mounting groove formed on the outer peripheral surface of the fluid pressure cylinder along the moving direction of the piston rod, and can be fixed with a fixing screw at any position. Attached to the hydraulic cylinder. When the position detection device is attached to the fluid pressure cylinder, the installer (operator) engages the position detection device with the attachment groove, moves the piston along the attachment groove to a position where the piston is to be detected, and displays the optimum position. The position detection device was attached and fixed to the position where the light emitting diode to be turned on was searched.

  In recent years, there has been a demand for further downsizing of the position detecting device, and a position detecting device having a substrate width of several mm is required. In a fluid pressure cylinder that is required to be miniaturized as a position detection device, the detection accuracy of the piston position by the position detection device is also about 1 to 1.5 mm in width of the optimum range, and the combined width of the allowable range and the optimum range is 2. There is a demand of about 5 mm. In order to meet such demands, it is preferable to set the magnetic sensor vertically (vertically) rather than horizontally (horizontal) with respect to the magnet.

  Here, as shown in FIG. 6, the vertical installation means that the position detection device 64 is attached along the attachment groove 63 a formed on the outer peripheral surface of the fluid pressure cylinder 61 so as to extend along the moving direction of the piston rod 62. In this state, one end surface in the width direction of the substrate 65 means a state in which it is arranged in a state of facing the annular magnet 67 attached to the piston 66. Horizontal installation means a state in which the front surface or the back surface of the substrate 65 is disposed so as to face the annular magnet 67 mounted on the piston 66.

  When placed vertically, the output of the magnetic sensor 68 (correctly the output of the magnetoresistive element constituting the magnetic sensor, but referred to as the output of the magnetic sensor) is the peak Pm at the center as shown in FIG. On both sides of the curve, a downward downward peak Ps appears. In the horizontal orientation, the output of the magnetic sensor 68 is a curve in which small upward peaks Ps appear on both sides of the central peak Pm as shown in FIG. 7B. Therefore, in the case of landscape orientation, when setting the threshold value, it is necessary to set a value larger than the peak value of the small peak Ps existing on both sides of the central peak Pm. The detection range determined by the central peak Pm as described above becomes narrow. On the other hand, in the case of the vertical placement, the small peak Ps existing on both sides of the central peak Pm is output as the negative side output. Therefore, when setting the threshold, the small peak Ps existing on both sides is not set. There is no problem. As a result, in the case of vertical installation, the degree of freedom for setting the threshold value is higher than in horizontal installation.

  When the position detection device 64 is attached to the fluid pressure cylinder 61, the lead wire 69 drawn from one end of the position detection device 64 is directed to either the rod side (the side where the piston rod 62 can be seen) of the fluid pressure cylinder 61 or the head side. It has good specifications and can select the orientation that is easy for the installer to use. However, in the configuration in which the two magnetic sensors 68 are mounted on one side of the substrate 65, the position detection device 64 is mounted so that the magnetic sensor 68 is on the right side of the substrate 65 in FIG. The distance between the magnetic sensor 68 and the magnet 67 is different between the case where the magnetic sensor 68 is attached to the groove 63a and the case where the position detecting device 64 is attached so as to be on the left side indicated by the broken line.

  It is known that the closer to the surface of the magnet 67, the larger the magnetic flux density, and the stronger the magnetic field acting on the magnetic sensor 68, the larger the output voltage peak value and the output curve for the generated magnetic field distribution. Even if the thickness of the substrate 65 is about 0.5 mm, the outputs of the two magnetic sensors 68 are different from each other, and the output voltage of the magnetic sensor 68 is the distance L1 between the magnetic sensor 68 and the magnet 67. 8 is in a state indicated by a solid line in FIG. 8, and when the magnetic sensor 68 and the magnet 67 are at a distance L2, a state indicated by a broken line in FIG. Further, as shown in FIG. 8, the operating range of the sensor and the lighting color of the indicator lamp determined from the outputs and threshold values of the two magnetic sensors 68 are red when either one of the sensor 1 and the sensor 2 is ON. When the sensor 1 and the sensor 2 are both in the ON state, the light is green. In the case of the near distance L1, the operation range and the green lighting range (optimum range) of the position detection device that processed the sensor signal are wider than in the case of the far distance L2.

  In FIG. 8, two magnetic sensors 68 are indicated as sensor 1 and sensor 2, and sensor ON means a detection state in which the output voltage of the sensor is equal to or higher than a threshold value. Sensor OFF means output of the sensor. It means a non-detection state in which the voltage is less than the threshold value.

  Thus, in the case of the position detection device in which the two magnetic sensors are arranged on one side of the substrate, the optimum range of the operation range varies depending on the mounting direction of the position detection device with respect to the mounting groove. As a result, in applications where the piston stop position varies (for example, when there is a large variation in the dimensions between workpieces fixed by the cylinder pressing pressure), the piston is less likely to stop within the optimum mounting range, and the overall Since the operating range is also narrowed, it may happen that the piston stop position deviates from the operating range of the magnetic sensor, making it impossible to detect the position.

  In addition, the small size of the fluid pressure cylinder and the improvement of the position detection accuracy of the piston reduce the width of the magnet (the length in the direction of movement of the piston), and the width of the magnet is the width of one magnetic sensor. If the two magnetic sensors are arranged adjacent to each other in the direction of movement of the piston on one surface of the substrate, they cannot be arranged so that a part of the operation range of the magnetic sensors overlaps. In order to arrange the two magnetic sensors on one side of the substrate so that a part of the operation range thereof is overlapped, it is necessary to dispose the two magnetic sensors 68 in the width direction of the substrate 65 as shown in FIG. There is. However, in this arrangement, the distances between the magnetic sensors 68 and the magnets 67 are different, making it difficult to configure the position detection device 64 using the magnetic sensors 68 having the same sensitivity.

  The present invention has been made in view of the above-described conventional problems, and its object is to provide a position detecting device even if it is attached to a fluid pressure cylinder such that the lead-out side of the lead wire is on the piston side or the head side. It is an object of the present invention to provide a fluid pressure cylinder position detecting device capable of performing stable position detection without changing the operation range of the above.

  In order to achieve the above object, according to the first aspect of the present invention, the output voltage of the magnetoresistive element showing the resistance value corresponding to the strength of the magnetic field from the magnetism generating means is compared with the reference voltage by the comparator and the comparison result is obtained. A position detection device for a fluid pressure cylinder provided with a magnetic sensor that outputs a vertical position with respect to a magnet provided on a piston of the fluid pressure cylinder when the position detection device is attached to the fluid pressure cylinder Two magnetic sensors arranged on the both sides of the substrate, in a state shifted one by one in the moving direction of the piston, and in a state where a part of the operation range overlaps, on both surfaces of the substrate, First display means that emits light when one of them is in a detection state, and second display means that emits light when both of the two magnetic sensors are in a detection state. Here, “vertical arrangement” means a state in which one end face in the width direction of the substrate is arranged so as to face the surface of the magnet attached to the piston.

  When the position detection device of the present invention is attached to the fluid pressure cylinder, the distances to the magnets of the two magnetic sensors attached to the both surfaces of the substrate one by one are different. When the mounting direction of the position detecting device with respect to the fluid pressure cylinder is changed by 180 degrees, the operating point of the position detecting device varies somewhat, but the operating range does not change. The optimum range in which both of the two magnetic sensors arranged in a state shifted in the moving direction of the piston and a part of the operation range overlap with each other is in the detection state does not change. Therefore, when the installer of the position detection device confirms the lighting state of the second display means and attaches the position detection device to the fluid pressure cylinder, the position detection device is attached to an appropriate position and stabilized regardless of the attachment direction. Position detection is possible.

  According to a second aspect of the present invention, in the magnetic sensor according to the first aspect, the magnetoresistive element and the comparator are formed of different chips. In the present invention, the degree of freedom of the arrangement position of the comparator is higher than when the magnetoresistive element and the comparator are integrated into one chip.

  According to a third aspect of the present invention, in the first aspect of the present invention, the magnetic sensor is an IC in which the magnetoresistive element and the comparator are integrated into one chip. In the present invention, the manufacture of the position detection device is simplified as compared with the case where the magnetoresistive element and the comparator are configured on separate chips.

  According to the present invention, even if the position detection device is attached to the fluid pressure cylinder so that the lead-out side of the lead wire is on the piston side or the head side, the operation range of the device does not change and stable position detection can be performed. it can.

  Hereinafter, an embodiment embodying the present invention will be described with reference to FIGS. A fluid pressure cylinder position detection device (hereinafter simply referred to as a position detection device) is used for detecting a piston position in a fluid pressure cylinder such as an air cylinder or a hydraulic cylinder.

  As shown in FIG. 1A, a plurality of mounting grooves 13a and 13b (two in this embodiment) are formed on the outer peripheral surface of the fluid pressure cylinder 11 so as to extend along the moving direction of the piston rod 12a. Yes. The position detection device 10 is attached to the fluid pressure cylinder 11 so as to be movable along the attachment groove 13a or the attachment groove 13b and to be fixed by a fixing screw 14 at an arbitrary position. Although not shown, the mounting grooves 13 a and 13 b may be provided on the other surface of the fluid pressure cylinder 11 in order to appropriately change the mounting position of the position detection device 10.

  As shown in FIG. 1 (b), a magnet 16 is provided in an annular shape in the receiving groove 15 formed on the outer peripheral surface of the piston 12. The position detection device 10 is configured to generate an output signal when the magnet 16 moves together with the piston 12 to a predetermined position. The position detection device 10 includes a circuit board 20 as a board, and various electronic components are mounted on the circuit board 20. As electronic components, there are two magnetic sensors 21 and 22, display means (not shown), transistors, resistors (all shown in FIG. 2), and the like. Various electronic components and the circuit board 20 are accommodated in the case 23 and molded with a resin (not shown). The two magnetic sensors 21 and 22 have the same performance. The case 23 is formed in a substantially rectangular parallelepiped shape, and a lead wire 24 is drawn from one end of the case 23. The position detection device 10 is fixed to the mounting groove 13a or the like with the surface opposite to the side from which the lead wire 24 is drawn facing the outer surface of the fluid pressure cylinder 11. Further, in order to make it possible to visually check the lighting state of the display means, the case 23 is partially transparent or partially thin.

  The circuit board 20 is accommodated in the case 23 so as to be vertically arranged with respect to the annular magnet 16 provided on the piston 12 of the fluid pressure cylinder 11 in a state where the position detection device 10 is attached to the fluid pressure cylinder 11. Has been. As shown in FIGS. 1B and 1C, the two magnetic sensors 21 and 22 are shifted in the moving direction of the piston 12 one by one on both surfaces of the circuit board 20 and part of the operation range. Are arranged in an overlapping state. FIGS. 1B and 1C schematically show the configuration of the position detection device 10 and the fluid pressure cylinder 11. For convenience of illustration, some dimensions are exaggerated for easy understanding. Therefore, the ratio of dimensions such as the width, length, and thickness of each part is different from the actual ratio.

Next, the electrical configuration of the position detection device 10 will be described with reference to FIG.
As shown in FIG. 2, the magnetic sensors 21 and 22 include a bridge circuit 25 including magnetoresistive elements 25 a and 25 b and a comparator 26. The magnetoresistive elements 25a and 25b are elements showing resistance values corresponding to the strength of the magnetic field from the magnetism generating means. The bridge circuit 25 is connected between the power supply Vcc and the ground GND, and includes two magnetoresistive elements 25a and 25b and two voltage dividing resistors 25c and 25d. The connection point of both magnetoresistive elements 25a and 25b is connected to the non-inverting input terminal of the comparator 26, and a magnetic detection signal is input to the comparator 26. The connection point of both voltage dividing resistors 25c and 25d is the comparator 26. The reference voltage Vr is input to the comparator 26. The comparator 26 compares the output signal from the bridge circuit 25, binarizes it, amplifies it, and outputs it. The comparator 26 compares the output voltage of the magnetoresistive elements 25a and 25b (that is, the input voltage Vi to the non-inverting input terminal of the comparator 26) with the reference voltage Vr, and the input voltage Vi is greater than the reference voltage Vr. Is also increased, an H (High) level signal is output.

  The output terminals of the magnetic sensors 21 and 22 are connected to the exclusive OR circuit 27 and the AND circuit 28. The output terminal of the exclusive OR circuit 27 is connected to the base terminal of the transistor Tr11 via the resistor R1. The collector terminal of the transistor Tr11 is connected to the cathode terminal of the light emitting diode LED1 as the first indicator lamp, and the anode terminal of the light emitting diode LED1 is connected to the power supply Vcc via the resistor R2. A light emitting diode whose lighting color is red is used for the light emitting diode LED1.

  The output terminal of the AND circuit 28 is connected to the base terminal of the transistor Tr12 via the resistor R1. The collector terminal of the transistor Tr12 is connected to the cathode terminal of the light emitting diode LED2 as the second indicator lamp, and the anode terminal of the light emitting diode LED2 is connected to the power source Vcc via the resistor R2. A light emitting diode whose lighting color is green is used for the light emitting diode LED2.

  The emitter terminals of the transistors Tr11 and Tr12 are connected to the base terminal of the transistor Tr13. The emitter terminal of the transistor Tr13 is connected to the ground GND, and the collector terminal of the transistor Tr13 is connected to the output terminal P. A Zener diode 29 is connected between the collector terminal and the emitter terminal of the transistor Tr13, and a resistor R3 is connected between the base terminal and the emitter terminal of the transistor Tr13.

Next, the operation of the position detection device 10 configured as described above will be described.
As shown in FIG. 1A, the position detection device 10 is used by being attached to a predetermined position of an attachment groove 13a of the fluid pressure cylinder 11, for example. When the fluid pressure cylinder 11 to which the position detection device 10 is attached operates and the piston 12 moves, the magnet 16 also moves together with the piston 12. As a result, the distance between the magnet 16 and each of the magnetic sensors 21 and 22 changes, and the magnetoresistive elements 25a and 25b become the input voltage Vi that is input to the non-inverting input terminal of the comparator 26 of each of the magnetic sensors 21 and 22. The voltage at the connection point (output voltage of the magnetoresistive element) also changes corresponding to the distance from the magnet 16.

  The output voltage of the magnetoresistive element becomes the input voltage Vi to the comparator 26 and is compared with the reference voltage Vr. If the input voltage Vi is higher than the reference voltage Vr, the output of the comparator 26, that is, the outputs of the magnetic sensors 21 and 22 are obtained. If the input voltage Vi is equal to or lower than the reference voltage Vr, the output of the comparator 26, that is, the outputs of the magnetic sensors 21 and 22 are L level signals. When an H level signal is output from either one of the magnetic sensors 21 and 22, the output of the exclusive OR circuit 27 becomes H level, the transistor Tr11 is turned on, and the red light emitting diode LED1 is turned on. At the same time, an H level signal is input to the base terminal of the transistor Tr13. As a result, the transistor Tr13 is also turned on and the output terminal P becomes L level, so that this signal can be used as a sequence control signal.

  When H level signals are output from both magnetic sensors 21 and 22, the output of the AND circuit 28 becomes H level, the transistor Tr12 is turned on, the green light emitting diode LED2 is turned on, and the transistor Tr13 is turned on. An H level signal is input to the base terminal. As a result, the transistor Tr13 is also turned on and the output terminal P becomes L level, so that this signal can be used as a signal for sequence control.

  Since the magnetic sensors 21 and 22 are respectively arranged on different surfaces of the vertically arranged circuit board 20, the shortest distance from the surface of the magnet 16 is different. The output voltage of the magnetoresistive element peaks when the distance between the magnetic sensors 21 and 22 and the magnet 16 is the shortest. Accordingly, as shown in FIG. 4, the position detection device 10 is mounted in the mounting groove 13a so that the lead wire 24 is pulled out to the piston rod 12a side, that is, the distance L1 between the magnetic sensor 21 and the magnet 16 is close. In such a state, the output voltages of the magnetoresistive elements of both magnetic sensors 21 and 22 are in a state indicated by a solid line in FIG. That is, the output voltage peak P1 in the magnetoresistive element of the magnetic sensor 21 having the shortest distance from the magnet 16 is higher than the output voltage peak P2 in the magnetoresistive element of the magnetic sensor 22, and the sensor operating range, that is, the output The magnetic sensor 21 is wider than the magnetic sensor 22 in the range where the voltage is larger than the threshold value (the reference voltage Vr of the comparator 26). In FIG. 3, what is indicated as sensor output is the output voltage of the magnetoresistive element, that is, the input voltage Vi input to the non-inverting input terminal of the comparator 26.

  Further, the position detection device 10 is mounted in the mounting groove 13a so that the lead wire 24 is pulled out to the head side of the fluid pressure cylinder 11, that is, the distance L1 between the magnetic sensor 22 and the magnet 16 is close. In the attached state, the output voltages of the magnetoresistive elements of both magnetic sensors 21 and 22 are in a state indicated by broken lines in FIG. That is, the peak P2 of the output voltage in the magnetoresistive element of the magnetic sensor 22 having the shortest distance from the magnet 16 is higher than the peak P1 of the output voltage in the magnetoresistive element of the magnetic sensor 21, and the sensor operating range, that is, the output The magnetic sensor 22 is wider than the magnetic sensor 21 in the range where the voltage is larger than the threshold value (the reference voltage Vr of the comparator 26).

  As shown in FIG. 3, when the magnetic sensor 21 and the magnetic sensor 22 are viewed, when the mounting direction of the position detection device 10 with respect to the fluid pressure cylinder 11 is changed, the operation range (a range in which the position detection device 10 is turned on) changes. Since the shape of the output indicated by the solid line and the shape of the output indicated by the broken line are axisymmetric shapes, comparing the case where the mounting direction of the position detection device 10 with respect to the fluid pressure cylinder 11 is different, both the magnetic sensors 21 and 22 are both The width (movement distance of the piston) of the ON range (the ON range of the green indicator light) is the same. However, since the point at which the magnetic sensors 21 and 22 are switched from OFF to ON shifts, the range in which either one of the magnetic sensors existing on both sides of the range in which both the magnetic sensors 21 and 22 are ON is turned on (red) The width of the ON range of the indicator lights is different. When the piston 12 moves from the retracted state to the projecting state of the piston rod 12a, the deviation amount X1 of the point at which the magnetic sensor 21 switches from OFF to ON, and the deviation amount X2 of the point at which the magnetic sensor 22 switches from ON to OFF. Is equal to Further, the deviation Y1 of the point at which the magnetic sensor 22 is switched from OFF to ON is equal to the deviation Y2 of the point at which the magnetic sensor 21 is switched from ON to OFF. Accordingly, the widths of the operation range of the position detection device 10 (a range in which at least one of the magnetic sensors 21 and 22 is turned on) and the optimum range (a range in which both the magnetic sensors 21 and 22 are turned on) are the same.

  Even when the position detection device 10 is mounted in the mounting groove 13b so that the lead wire 24 is drawn out to the piston rod 12a, the distance L1 between the magnetic sensor 22 and the magnet 16 is close. That is, without changing the direction of the position detection device 10, which of the magnetic sensors 21 and 22 is closer to the magnet 16 is determined by which of the attachment grooves 13 a and 13 b is attached.

  Even when the optimum range of the position detection device 10 is deviated, when the position detection device 10 is attached to 11, the installer (operator) targets the position at which the green light emitting diode LED2 indicating that it is in the optimum range is lit. Since the position detecting device 10 is fixed as described above, fluctuations are absorbed during mounting and fixing, so there is no problem.

According to this embodiment, the following effects can be obtained.
(1) The position detection device 10 includes magnetic sensors 21 and 22 that compare the output voltage of the magnetoresistive element with the reference voltage Vr by the comparator 26 and output the comparison result. Then, in a state where the position detection device 10 is attached to the fluid pressure cylinder 11, the pistons 12 are arranged one by one on both surfaces of the circuit board 20 arranged vertically with respect to the magnet 16 provided on the piston 12 of the fluid pressure cylinder 11. The magnetic sensors 21 and 22 are arranged in a state where they are shifted in the moving direction and a part of the operation range overlaps. Therefore, even if the position detection device 10 is attached to the fluid pressure cylinder 11 so that the lead wire 24 is pulled out to the piston 20 side or the head side, the operation range of the device does not change and stable position detection can be performed. it can.

  (2) The light emitting diode LED1 that emits light when one of the two magnetic sensors 21 and 22 is in a detection state and the light emitting diode LED2 that emits light when both of the two magnetic sensors 21 and 22 are in a detection state are provided. Therefore, when the installer of the position detection device confirms the lighting state of the light emitting diode LED2 and attaches the position detection device 10 to the fluid pressure cylinder 11, the position detection device 10 is attached to an appropriate position regardless of the attachment direction. Stable position detection is possible.

  (3) The magnetic sensors 21 and 22 are ICs in which the magnetoresistive elements 25a and 25b and the comparator 26 are integrated into one chip. Therefore, the manufacturing of the position detection device 10 is simplified as compared with the case where the magnetoresistive elements 25a and 25b and the comparator 26 are configured in different chips.

The embodiment is not limited to the above, and may be configured as follows, for example.
In the magnetic sensors 21 and 22, the magnetoresistive elements 25a and 25b and the comparator 26 may be configured by different chips. In this case, the comparator 26 can be arranged away from the magnetoresistive elements 25a and 25b, and the arrangement of the comparator 26 is compared with the case where the magnetoresistive elements 25a and 25b and the comparator 26 are integrated into one chip. The degree of freedom of position becomes high.

First display means that emits light when one of the two magnetic sensors 21 and 22 is in a detection state;
The second display means that emits light when both of the two magnetic sensors 21 and 22 are in a detection state is not limited to a combination of a red light emitting diode (LED) and a green light emitting LED, but LEDs of different colors. It is good also as a structure which combined.

  The first display unit and the second display unit are not limited to the configuration in which the light emitting elements of different colors are lit, but the configuration in which the emission color is the same and the area of the light emitting unit is changed, or the number of the light emitting units is different. May be. For example, one LED may be turned on when one of the two magnetic sensors 21 and 22 is in a detection state, and two LEDs may be turned on when both of the two magnetic sensors 21 and 22 are in a detection state.

-A display means is not restricted to a light emitting diode, You may use light emitting elements other than a light emitting diode, for example, an electroluminescent element (EL element).
Other transistors, for example, MOS transistors (MOSFETs) may be used as the transistors Tr11 to Tr13 in place of the bipolar transistors.

  The magnetic sensor so that the first display means emits light when one of the two magnetic sensors 21 and 22 is in the detection state, and the second display means emits light when both of the two magnetic sensors 21 and 22 are in the detection state. The circuit configuration for processing the outputs of 21 and 22 is not limited to the combination of the exclusive OR circuit 27 and the AND circuit 28.

  A processing circuit (for example, the exclusive OR circuit 27 and the AND circuit 28) that processes the outputs of the two magnetic sensors 21 and 22 without incorporating the first display means and the second display means as a position detection device. It is good also as a structure provided with the output terminal. The output terminal of the processing circuit may be connected to a separate display unit or microcomputer to check the optimum range and the allowable range.

Next, technical ideas that can be grasped from the above-described embodiment and other examples will be described below together with their effects.
(1) In the invention according to any one of claims 1 to 3, the first display means is a red light emitting diode, and the second display means is a green light emitting diode. In this case, many of the components of the conventional two-color light emission position detecting device can be used.

  (2) The position for the fluid pressure cylinder provided with the magnetic sensor for comparing the output voltage of the magnetoresistive element showing the resistance value corresponding to the strength of the magnetic field from the magnetism generating means with the reference voltage and the comparator and outputting the comparison result In the state in which the position detection device is attached to the fluid pressure cylinder, one detection device is provided on a substrate vertically disposed with respect to a magnet provided on a piston of the fluid pressure cylinder, and on both surfaces of the substrate. Two magnetic sensors arranged in a state where they are displaced in the moving direction of the piston one by one and a part of the operation range is overlapped, and one of the two magnetic sensors by inputting the output signals of the two magnetic sensors The first output unit (exclusive OR circuit 27) that outputs a first output signal indicating that the two magnetic sensors are in a detection state, and the two magnetic sensors output signals are input to the two magnetic sensors. Position detecting apparatus for a fluid pressure cylinder having a second output portion which both capacitors and outputs a second output signal indicating that the detected state and (AND circuit 28). According to the invention described in (2), even if the position detection device is attached to the fluid pressure cylinder so that the lead-out side of the lead wire is on the piston side or the head side, the operation range of the device does not change and is stable. Position detection can be performed. In addition, the position detection device can be downsized as compared with a configuration in which the position detection device includes a light emitting display means for confirming the detection state.

(A) is a schematic perspective view of a fluid pressure cylinder, (b) is a schematic diagram which shows the relationship between a fluid pressure cylinder and a position detection apparatus, (c) is a schematic cross section of a position detection apparatus. The circuit diagram which shows the electric constitution of a position detection apparatus. The relationship figure which shows the output voltage of a magnetic sensor, and the light emission state of a light emitting diode. The schematic diagram which shows the relationship between a position detection apparatus and a fluid pressure cylinder. (A)-(d) is explanatory drawing of operation | movement of the position detection apparatus of a prior art. The schematic diagram which shows the relationship between the position detection apparatus of another prior art, and a fluid pressure cylinder. (A) is a diagram which shows the output voltage of the magnetic sensor in the case of vertical arrangement, (b) is a diagram showing the output voltage of the magnetic sensor in the case of horizontal arrangement. The diagram which shows the output voltage of the magnetic sensor by the difference in the attachment state of a position detection apparatus, and the light emission state of a light emitting diode. The schematic diagram which shows the relationship between a board | substrate and a magnetic sensor at the time of changing arrangement | positioning of a magnetic sensor.

Explanation of symbols

  LED1 ... light emitting diode as first display means, LED2 ... light emitting diode as second display means, Vr ... reference voltage, 10 ... position detecting device, 11 ... fluid pressure cylinder, 12 ... piston, 16 ... magnet, 20 ... Circuit boards as boards, 21, 22 ... Magnetic sensors, 25a, 25b ... Magnetoresistive elements, 26 ... Comparators.

Claims (3)

A fluid pressure cylinder position detection device comprising a magnetic sensor for comparing the output voltage of a magnetoresistive element exhibiting a resistance value corresponding to the strength of a magnetic field from a magnetism generating means with a reference voltage and outputting a comparison result. There,
In a state where the position detection device is attached to a fluid pressure cylinder, a substrate that is vertically disposed with respect to a magnet provided on a piston of the fluid pressure cylinder;
Two magnetic sensors disposed on both surfaces of the substrate one by one in a state shifted in the moving direction of the piston and in a state where a part of the operation range overlaps;
First display means for emitting light when one of the two magnetic sensors is in a detection state;
A fluid pressure cylinder position detecting device comprising: a second display means for emitting light when both of the two magnetic sensors are in a detection state.   The fluid pressure cylinder position detecting device according to claim 1, wherein the magnetic sensor includes the magnetoresistive element and the comparator formed of different chips.   The fluid pressure cylinder position detecting device according to claim 1, wherein the magnetic sensor is an IC in which the magnetoresistive element and the comparator are integrated into one chip.

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