JPH07100785A - Air chuck having switch - Google Patents

Abstract

PURPOSE:To provide an air chuck equipped with a magnetic linear scale which can correctly measure the position of the piston of the air chuck by carrying out the sufficient temperature compensation even if the environmental temperature varies within a narrow width. CONSTITUTION:An air chuck having a switch is an air chuck for holding a held article by shifting a piston 14 by the action of the compressed air and shifting a pair of chucking hooks 22 by a piston rod 28, and is equipped with a magnetic linear scale 23 which outputs the position of the piston 14 as the linear analogue data, and a detecting circuit which detects the nipping state of a pair of chuck hooks 22 on the basis of the analogue data outputted by the magnetic linear scale 23.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air chuck for holding an object to be held by a pair of chuck claws driven by an air cylinder. More specifically, the position of a permanent magnet attached to a piston of the air cylinder is set. The present invention relates to an air chuck with a switch having a magnetic linear scale for detection.

[0002]

2. Description of the Related Art In a conventional air chuck switch, a permanent magnet is attached to the piston portion like other fluid pressure cylinders with a switch, and the position of the piston is detected by using a magnetic resistance element or the like as a magnetic detector. . The structure of the internal circuit of the switch is shown in FIG. The magnetoresistive element 101 is formed of a pattern of a ferromagnetic metal thin film. A DC voltage is applied across the magnetoresistive element 101, and the voltage at the midpoint of the magnetoresistive element 101 is connected to the comparator 104. Further, the comparator 104 is supplied with the comparison voltage set by the reference voltage forming resistors 102 and 103. The output of the comparator 104 is the current limiting resistor 10
5. Connected to the base of the output transistor 107 via the indicator light. The emitter of the output transistor 107 is
It is connected to ground and the output is available from the collector.

FIG. 1 shows an output waveform of the magnetoresistive element 101 of the magnetic detector when the air chuck switch is operated.
6 shows A. The comparison voltage of the comparator 104 is set to B. Therefore, the output of the comparator 104, the lighting timing of the indicator lamp, and the output are as shown in FIG. Here, since the output of the magnetoresistive element 101 has no linearity, the magnetoresistive element 101 can only be used to confirm the position of the magnet attached to the piston. Therefore, two magnetic detectors have been attached in correspondence with the open piston position and the closed piston position of the air chuck to check the open and closed states of the air chuck. Further, in order to confirm that the air chuck has grasped the object, it has been desired to detect the piston at the intermediate position.

However, since the piston stroke of the air chuck is generally as short as 2 to 4 mm, it is necessary to attach three magnetic detectors to detect the open state, the closed state, and the work gripping state of the air chuck. It was difficult.
The reason why it was difficult is explained below. That is, in order to detect a few places in a narrow range, (1) reduce the thickness of the magnet of the piston in the magnetizing direction, (2) reduce the switch sensitivity, that is, the comparison shown in FIG. The voltage B is increased, and (3) the output of the two magnetic detectors is ANDed. However, (1),
In the case of (2), there is a problem that the switch that has been conventionally operated does not operate due to the temperature characteristics of the magnet and the approach of a magnetic material such as iron located outside. Therefore, the operating range of the magnetic detector shown as the operating range of the output transistor in FIG. 16 is technically 4 mm.
For example, when two magnetic detectors are used when the stroke of the air chuck piston is 3 mm, an area in which the two magnetic detectors are simultaneously turned on occurs as shown in FIG. Therefore, the determination must be performed by the control circuit, which is extremely complicated. Also,
(3) has a problem that the internal circuit becomes complicated and the internal current consumption increases.

On the other hand, attempts have been made to give the magnetoresistive element 101 linearity. That is, use of a magnetic sensor formed by a magnetoresistive element pattern as a linear scale is described in Japanese Utility Model Publication No. 57-6962. FIG. 18 shows a conventional magnetic linear scale. Magnetoresistive element 51 and temperature compensation element 52
Are formed as a pattern having a constant line width. The patterns of the magnetoresistive element 51 and the temperature compensating element 52 are formed so as to have a quadrature phase difference. The magnetoresistive element 51 and the temperature compensating element 52 have the property that the internal resistance value decreases when a magnetic field is applied at right angles to the longitudinal direction of the pattern lines. When a magnetic field is applied to, the internal resistance value does not change. Therefore, when the permanent magnet 57 moves in the direction of arrow B as shown in FIG.
, The internal resistance value of the temperature compensation element 52 does not change. Therefore, the position of the permanent magnet can be detected by measuring the change in the internal resistance of the magnetoresistive element 51.

On the other hand, the magnetoresistive element formed by the pattern of the ferromagnetic metal thin film has a large temperature dependence, and there is a practical problem as it is. Ferromagnetic metal generally has a property that its internal resistance changes depending on temperature, and a magnetoresistive element is easily affected by temperature change because it has a thin film pattern. Therefore, the internal resistance of the magnetoresistive element changes not only with the strength of the magnetic field but also with the ambient temperature. As a means for solving this problem, as shown in FIG. 18, the temperature compensating circuit 5 having the same shape as the magnetoresistive element 51 but having different directions.
2 was provided on the same substrate to differentially perform temperature compensation. That is, when the magnet 57 is moved parallel to the longitudinal direction of the pattern line of the magnetoresistive element 51, the internal resistance value of the magnetoresistive element 51 decreases, but the internal resistance value of the temperature compensation element 52 does not change depending on the magnetic field. . Therefore, the change in the internal resistance value of the temperature compensation element 52 directly represents only the temperature change. On the other hand, the internal resistance value of the magnetoresistive element 51 changes depending on both the strength of the magnetic field and the ambient temperature. Therefore, the change in the internal resistance value of the magnetoresistive element 51 can be temperature-compensated by the change in the internal resistance value of the temperature compensating element 52.

[0007]

However, the use of the magnetic linear scale for detecting the position of the magnet attached to the piston of the air chuck has the following problems. (1) It is difficult for the conventional magnetic linear scale to detect a magnet attached to a piston having a wide width and a small diameter such as a piston of an air chuck. Further, the conventional magnetic linear scale has a problem that it has a wide width and the air chuck becomes large. Further, since the magnetic linear scale changes in the width direction, when the position of the permanent magnet is displaced in the width direction, the output of the magnetic linear scale fluctuates greatly. Therefore, it is necessary to attach the magnetic linear scale to the permanent magnet with high accuracy, and there is a problem that the usability is poor.

(2) In order to perform temperature compensation differentially using the magnetoresistive element 51 and the temperature compensating element 52 as in the prior art, the magnetoresistive element 51 and the temperature compensating element 5 are used.
It was necessary to accurately control the dimensions of No. 2. In order to temperature-compensate the change in the internal resistance value due to the temperature change of the magnetoresistive element 51, the magnetoresistive element 51 and the temperature compensating element 5
This is because if the dimensional accuracy of 2 is poor, an extra experiment for determining a complicated operation or a constant is required. Here, with respect to the dimensions of the magnetoresistive element 51 and the temperature compensating element 52, the film thickness is determined by vapor deposition, and the line width of the pattern is determined by etching. Of these, the wet etching process is
Since it greatly varies depending on the concentration of the etching solution, the solution temperature, etc., it is difficult to accurately process the line width of the pattern to a predetermined width. Therefore, it is difficult to improve the processing accuracy of the magnetoresistive element 51 and the temperature compensating element 52, and for that reason, extra cost is generated. This is especially a problem when the magnetic sensor is used in an environment in which the ambient temperature changes within a range of several tens of degrees. (3) The above-mentioned problem has not only occurred in the air chuck but also in the single-stroke cylinder in general.

The present invention has been made to solve the above-mentioned problems, and it is possible to accurately measure the piston position of the air chuck by performing sufficient temperature compensation even if the width is narrow and the ambient temperature changes. It is an object to provide an air chuck equipped with a possible magnetic linear scale.

[0010]

In order to achieve this object, (1) In an air chuck with a switch of the present invention, a piston is moved by the action of compressed air, and a pair of chucks is provided by a rod provided on the piston. An air chuck that moves a claw to grip an object to be gripped, and grasps a pair of chuck claws based on the linear scale that outputs the piston position as linear analog data and the analog data that the linear scale outputs. And a chuck grip detection means for detecting (2) In the device described in (1) above, the linear scale is formed by a vapor-deposited thin film of a ferromagnetic metal on a substrate, and is composed of a magnetoresistive element that exhibits a magnetoresistive effect. The magnetic linear scale is characterized in that the permanent magnet attached to the piston is formed with a constant width in the direction orthogonal to the moving direction, and the density linearly changes in the moving direction of the permanent magnet.

(3) In the air cylinder with a switch of the present invention, based on the linear scale which outputs the position of the piston moved by the action of compressed air as linear analog data, and the analog data which the linear scale outputs. An intermediate position detecting means for detecting an intermediate position of the piston, wherein the linear scale is formed by a vapor deposition thin film of a ferromagnetic metal on a substrate, and is composed of a magnetoresistive element that exhibits a magnetoresistive effect, The magnetoresistive element is a magnetic linear scale that is formed with a constant width in a direction orthogonal to a direction in which the permanent magnet attached to the piston moves, and has a density that linearly changes in the direction in which the permanent magnet moves. And

(4) In the structure described in (2) or (3) above, the magnetoresistive elements have the same line width,
It is characterized in that the density is sequentially changed in the direction in which the permanent magnet moves. (5) In the device described in (2) or (3) above, the magnetoresistive element sequentially changes the line width in the direction in which the permanent magnet moves. (6) In the device described in (2) or (3) above, the magnetoresistive element sequentially changes the density of a pattern having a wide line width in the moving direction of the permanent magnet. (7) In the device described in (2) or (3) above, the magnetoresistive element is characterized in that the line width and the density are sequentially changed in a direction in which the permanent magnet moves.

[0013]

In the air chuck with a switch of the present invention having the above-mentioned structure, the piston driven by the action of compressed air moves the pair of chuck claws in parallel to grip the object to be grasped. At this time, the position of the piston is at an intermediate position between the open state and the closed state. The magnetic linear scale of the magnetic detector, which is a switch, uses an electric power according to the strength of the magnetic field generated by the permanent magnet when the permanent magnet fixed to the piston moves in parallel with the magnetic linear scale while maintaining a constant distance. Resistance decreases. At this time, since the density of the magnetic linear scale changes linearly in the moving direction of the permanent magnets, there is a one-to-one correspondence between the position of the permanent magnets and the reduced value of the electrical resistance value. Therefore, the position of the piston can be measured by measuring the change in the resistance value. By comparing this resistance value with a reference value, it is determined whether the air chuck is in an open state, a closed state, or a state of gripping an object, and outputs the determination.

When the ambient temperature changes, the internal resistance value of the magnetoresistive element also changes according to the ambient temperature. On the other hand, since the temperature compensating circuit is composed of a pattern having a line width smaller than the line width of the pattern forming the magnetoresistive element, the temperature compensating circuit is affected by the change in the strength of the magnetic field as compared with the magnetoresistive element. Since it is less likely to be affected, the temperature of the magnetoresistive element can be accurately compensated. Furthermore, if the line width of the pattern of the temperature compensation circuit is formed to be 6 μm or less, the internal resistance value of the temperature compensation circuit is hardly affected by the strength of the magnetic field and changes only by the ambient temperature. The temperature of the magnetoresistive element can be easily compensated by using the compensation circuit.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An air chuck with a switch, which is an embodiment of the present invention, will be described below with reference to the drawings. The structure of an air chuck with a switch is shown in FIG. A cylinder hole 12 having a bottomed cylindrical hole is formed at the center position of the left end surface of the air chuck body 27 having a rectangular parallelepiped shape. A rod hole 29 is formed at the center of the bottom of the cylinder hole 12. A piston 14 is slidably fitted in the cylinder hole 12. A rod 18 which is integral with the piston 14 projects to the outside from a rod hole 29. The permanent magnet 13 is attached to one of the two grooves formed on the outer circumference of the piston 14. In addition, the O-ring is attached to the other groove. The opening at the right end of the cylinder hole 12 is hermetically closed by screwing a sealing screw 17 into a female screw portion formed in the cylinder hole 12. The piston 14 is biased to the left by a return spring 16 attached to a sealing screw 17.
A drive air hole (not shown) is formed in the chamber on the left side of the piston in the cylinder hole 12.

A pair of chuck claws 22 are attached to the left end surface of the air chuck so as to be movable in parallel by a guide (not shown). The notch of the arm 20 is slidably fitted to the operating shaft 21 formed near the right end of the chuck claw 22. The pair of arms 20 is attached so as to be rotatable around a fulcrum shaft 30. The rod 1 has an engagement hole (not shown) formed at a position opposite to the cutout portion of the pair of arms 20.
8 is rotatably engaged with an engaging hole at the tip of the stopper 8 and a stop pin 19. On the other hand, a magnetic detector 11 which is a switch is attached at a position parallel to the cylinder hole 12. The structure of the magnetic detector 11 is shown in FIG. 2B is a cross-sectional view when the magnetic detector 11 is viewed from the same direction as FIG. FIG. 2A is a side view thereof. Inside the magnetic detector 11, the magnetic linear scale 23 and the detection circuit 3 are provided.
1 and 1 are fixed.

First, the operation of the air chuck having the above structure will be described. A sensor (not shown) detects that the target object is between the pair of chuck claws 22, the compressed air is sent to the cylinder hole 12, and the pair of chuck claws 22 are moved in parallel to grip the target object. Piston 1 at this time
Since the position of No. 4 is constant depending on the object, whether or not the air chuck is holding the object is detected by detecting the position of the permanent magnet 13 fixed to the piston 14 in the grip state by the magnetic detector 11. It is possible to judge whether or not.

Next, the magnetic linear scale 23 used in the present invention will be described in detail. Four types of schematic configurations of the magnetic linear scale 23 are shown. FIG. 3 shows a first embodiment in which the line width W1 of the magnetoresistive element R1 is constant and the density is sequentially changed. FIG. 4 shows a second embodiment in which the density of the magnetoresistive element R1 is constant and the line width is sequentially changed. FIG. 5 shows a third embodiment in which the density of the magnetoresistive element R1 is constant and the density of a pattern having a wide line width is sequentially changed. FIG. 6 shows a fourth embodiment in which the first embodiment and the second embodiment are combined. In each of the embodiments, the magnetoresistive element R1 is formed with a constant width WB in the direction orthogonal to the direction B in which the permanent magnet 57 moves, and the density changes linearly in the direction B in which the permanent magnet 13 moves.

FIG. 7 shows the configuration of the first embodiment of the magnetic linear scale 23 using the magnetoresistive element R1. On the magnetic linear scale 23, two serpentine patterns of the magnetoresistive element R1 and the temperature compensating circuit R2 are formed so as to each have a phase difference of a right angle. Here, as shown in the partially enlarged view of FIG. 8A, the magnetoresistive element R1 is formed in a constant zigzag pattern with a line width W1 = 20 μm. The zigzag spacing WA of the magnetoresistive element R1 is from WA1 = 1.085 mm at the left end portion to WA77 = 0.325 mm at the right end portion, and the zigzag spacing WA is decreased by 0.01 mm to make 39 reciprocations. . As a result, the density of the magnetoresistive element R1 is changed to three times or more. The magnetic linear scale 23 of this embodiment has a width of 3 mm and a length of about 60 mm. According to the magnetic linear scale 23 of the present embodiment, the width of the zigzag pattern of the magnetoresistive element R1 is kept constant,
Since the density is changed, the width of the magnetic linear scale 23 can be reduced to 3 mm.

The temperature compensating circuit R2 is shown in FIG.
As shown in the partially enlarged view, the line width W2 is 4 μm and the pattern is formed as a four-fold zigzag folded pattern. In this embodiment, as the ferromagnetic metal that is the material of the magnetoresistive element R1 and the temperature compensating circuit R2, permalloy (Ni-F) is used.
e, 83:17). Magnetoresistive element R1
Has a property that the resistance value decreases when a magnetic field is applied at right angles to the longitudinal direction of the pattern lines, and the resistance value decreases when a magnetic field is applied in the longitudinal direction of the pattern lines. It does not change. Terminal portions 24, 25 are provided at both ends of the magnetoresistive element R1.
Is provided, and terminal portions 25, 2 are provided at both ends of the temperature compensation circuit R2.
6 are provided.

Next, the detection circuit of the magnetic detector 11 will be described. FIG. 11 shows the detection circuit 3 of the magnetic linear scale 23.
1 is shown. A DC voltage Vcc is applied between the terminals 24 and 26 of the magnetic linear scale 23. The midpoint voltage 25 of the magnetic linear scale 23 is connected to the negative side input of the first comparator 45 and the positive side input of the second comparator 46. On the other hand, the minus side input of the second comparator 46 is connected to the ground via the resistor 49, and the plus side input of the first comparator 45 is V via the variable resistor 47.
connected to cc. Further, the positive side input of the first comparator 45 and the negative side input of the second comparator E2 are connected via a resistor 48. Variable resistor 47
The resistors 48 and 49 supply the higher reference voltage E1 to the first comparator 45 and the lower reference voltage E2 to the second comparator 46. Here, in the air chuck with a switch of the present embodiment, the reference voltages E1 and E2 are
Sets the upper and lower limit values of the position of the permanent magnet 13 fixed to the piston 14 in the state where the pair of chuck claws 22 hold the object.

The outputs of the first and second comparators 45 and 46 are connected to Vcc via the base of the transistor 42 and a resistor. The collector of the transistor 42 is connected to Vcc via the light emitting diode 44 and the resistor. The emitter of the transistor 42 is connected to the base of the transistor 43. The collector of the transistor 43 is connected to the output terminal 41. The emitter of the transistor 43 is connected to ground.

Next, the operation of the detection circuit 31 having the above structure will be described. The midpoint voltage of the magnetic linear scale 23 has the waveform shown in FIG. That is, FIG. 14 shows experimental data of the magnetic linear scale 23 of the first embodiment. The horizontal axis indicates the position of the permanent magnet 13 as a moving distance,
The vertical axis represents the output S. The permanent magnet 13 has a cylindrical shape attached to the piston 14 and has a thickness of 1 mm. Permanent magnet 13
2 is data of an experiment in which a permanent magnet is translated in the longitudinal direction of the magnetic linear scale 23 in a state where the distance between the magnetic linear scale 23 and the magnetic linear scale 23 is 2 mm. As the permanent magnet 13 moves from the left end to the right end of the magnetic linear scale 23, the density of the magnetic linear scale 23 increases, and the internal resistance of the magnetoresistive element R1 decreases. It decreases in proportion to the decrease in the internal resistance of R1. Therefore, from FIG. 14, the moving distance of the permanent magnet 13 is 40
It can be seen that the position of the permanent magnet 13 can be linearly detected by the output S if it is within mm. With the air chuck,
Since the operating range of the piston 14 is about 4 mm, the magnetic linear scale 23 can accurately detect the position of the permanent magnet 13 fixed to the piston 14.

The midpoint voltage of the magnetic linear scale 23 is E1.
When it is higher or lower than E2, the outputs of the first and second comparators 45 and 46 are both at the low level and no voltage is applied to the bases of the transistors 42 and 43, so the transistors 42 and 43 are turned off. Next, when the midpoint voltage is between E1 and E2, the outputs of the first and second comparators 45 and 46 both become high level, and the voltage is applied to the base of the transistor 42.
A current flows through the light emitting diode 44 and the light emitting diode 44 is turned on. further,
Since a voltage is applied to the base of the transistor 43, the output S
Turns on. This makes it possible to accurately determine whether or not the chuck claw 22 is gripping the target object. A graph of the above relationship is shown in FIG.

By changing the variable resistor 47, it is possible to realize the magnetic detector 11 having an operating range of 1 mm or less, which is difficult with the prior art. At this time, even if the variable resistor 47 is changed, the sensitivity of the magnetic detector 11 is not affected, so that stable operation can be achieved even if the operating range is narrow. Further, since the output signal can be turned on at an arbitrary position of the permanent magnet 13 by changing the variable resistance 47, when the magnetic detector 11 is set so as to detect the object grasping state, Since it can be set only by the variable resistor 47 without moving the detector 11, it is easy to use. Further, even when the target object changes, the setting is easy. Further, since the magnetic detector 11 of the present embodiment has a narrower width than the conventional switch, it is possible to attach three magnetic detectors 11, thereby detecting the open state and the closed state. , And the position of each of the states in which the object is gripped can be detected. In the present embodiment, the magnetic detector 11 detects the position by the output of the magnetic linear scale 23 and outputs the output as the ON / OFF signal. However, the position signal output of the magnetic linear scale 23 is output as it is, and the external control device is used. The piston 14 position may be calculated by Then, only one magnetic detector 11 needs to be attached to detect the open state, the closed state, and the gripped state.

Next, the case where the ambient temperature changes will be described. The temperature compensation circuit R2 will be described. The data that the present inventor conducted an experiment are shown in FIG. The horizontal axis represents the line width of the pattern in units of microns, and the vertical axis represents the magnetoresistance change rate when the pattern is used as the magnetoresistive element R1. The data of the magnetic field strength of 100 gauss is shown by the dotted line L1, the data of the magnetic field strength of 50 gauss is shown by the alternate long and short dash line L2, and the data of the magnetic field strength of 25 gauss is shown by the solid line L3. Show.

According to this data, it can be seen that the rate of change in magnetoresistance of the magnetoresistive element decreases as the pattern width decreases. Therefore, if a pattern having a line width smaller than the pattern width of the magnetoresistive element R1 is used as the temperature compensating circuit R2, the influence of the magnetic field strength of the temperature compensating circuit R2 is small. It is possible to perform temperature compensation more accurately than the temperature compensation circuit 52 that has been used. That is, as compared with the case of the temperature compensation circuit using a pattern with a large line width, the temperature compensation circuit using a pattern with a small line width is less affected by the strength of the magnetic field. Even if there is an error in the manufacturing precision of, accurate temperature compensation can be performed.

Further, from this data, it is understood that the rate of change in magnetoresistance is remarkably reduced when the line width of the line forming the pattern of the magnetoresistive element is 6 μm or less. Therefore, it can be seen that if the pattern width is 6 μm or less, even if a ferromagnetic metal thin film, which is the same material as the magnetoresistive element, is used, the rate of change in the internal resistance of the thin film due to the strength of the magnetic field is small. On the other hand, the change in internal resistance due to the change in ambient temperature is
Since it is not affected by the pattern width, it can be seen that if the ferromagnetic metal thin film is formed with a pattern width of 6 μm or less, it has excellent properties as a temperature compensation circuit. That is, since the temperature compensating circuit R2 is composed of a ferromagnetic metal thin film made of the same material as the magnetoresistive element R1 and has a pattern width of 6 μm or less, the temperature compensating circuit R2 may be different due to variations in the etching process in the manufacturing process. Is almost unaffected, so accurate temperature compensation can always be performed.
Further, the shape of the temperature compensating circuit R2 can be determined regardless of the shape of the magnetoresistive element R1, and the temperature compensating circuit R2 can be downsized as shown in FIG.

Next, the second magnetic linear scale will be described. FIG. 9 shows the configuration of the second embodiment of the magnetic linear scale 23 using the magnetoresistive element R1. On the magnetic linear scale 23, two serpentine patterns of the magnetoresistive element R1 and the temperature compensating circuit R2 are formed so as to each have a phase difference of a right angle. Here, the magnetoresistive element R1 has a line width W1 of 0.5 μ each from 4 μ at the left end to 42.5 μ at the right end, as shown in a partially enlarged view of FIGS. While expanding the width, 39
It reciprocates to form a zigzag pattern. here,
The interval WA of the zigzag is 0.705 mm, which is constant.
As a result, the density of the magnetoresistive element R1 changes about 10 times at the left end and the right end.

The temperature compensating circuit R2 has a line width W2 = 4 μm and a line width W2 = 4 μm, as shown in a partially enlarged view of FIG.
It is formed as a reciprocating zigzag pattern. In this embodiment, as the ferromagnetic metal which is the material of the magnetoresistive element R1 and the temperature compensation circuit R2, permalloy (Ni) is used.
-Fe, 83:17) is used. Magnetoresistive element R
1 has a property that the resistance value decreases when a magnetic field is applied at right angles to the longitudinal direction of the pattern lines, and the resistance value decreases when a magnetic field is applied in the longitudinal direction of the pattern lines. Does not change. Terminal portions 24, 2 are provided at both ends of the magnetoresistive element R1.
5 is provided, and terminal portions 25,
26 are provided. According to the second embodiment, the density of the magnetoresistive element R1 can be three times or more that of the first embodiment.
The detection sensitivity of the permanent magnet 13 can be increased.

Next, in the third embodiment, as shown in FIG.
At the left end, one of the four zigzag folds has a wide line width, and the next four zigzag folds has two wide lines,
In the next four spelling folds, three have a wide width and the next four
Four of the zigzag folds of the book have a wide width. In this way, by sequentially changing the density of the line having a wide width, the density is linearly changed while having the constant width WB. Next, according to the fourth embodiment, since the first embodiment and the second embodiment are combined, the density of the magnetoresistive elements R1 is 3 at the left end and the right end of the magnetic linear scale 23.
Since it can be changed by 0 times, the detection sensitivity of the permanent magnet 13 can be further increased.

As described in detail above, according to the air chuck with switch of this embodiment, the magnetic linear scale 2
Since the position of the permanent magnet 13 fixed to the piston 14 is linearly measured by No. 3, if the object is determined, whether the air chuck is gripping the object by setting the corresponding piston position. Can be judged. Further, according to the magnetic linear scale of the present embodiment, the magnetoresistive element R1 is formed with a constant width in the direction orthogonal to the moving direction of the permanent magnet, and the density linearly changes in the moving direction of the permanent magnet. Therefore, the position of the permanent magnet can be detected linearly and accurately over a long range.
Further, since the magnetic linear scale 23 can be manufactured with a narrow width of 3 mm, it is compact without taking up a space, and the three magnetic detectors 11 can be attached to the air chuck. Further, since the magnetic linear scale 23 has uniformity in the width direction, even if the magnetic linear scale 23 is laterally displaced with respect to the permanent magnet, the change in output is small and the magnetic linear scale 23 can be easily attached.

Although the air chuck with a switch using the linear scale has been described in detail above, the effect is the same even if the rod is used as it is without using the chuck claw. Therefore, it can be used as a normal single-stroke cylinder, and when used as a single-stroke cylinder, there is an effect that it is possible to easily detect the intermediate position of the piston, which was difficult in the past.

The present invention is not limited to the above embodiment, but various applications are possible. For example, in this embodiment,
Permalloy (Ni-Fe, 8
3:17) is used, but it is the same when the composition ratio of the alloy is changed. Also, as a material, Ni or Ni
The same applies when -Co is used. Further, although the bias magnet is not used in this embodiment, the same effect can be obtained when the bias magnet is used for the magnetoresistive element. Further, in the present embodiment, the density, the line width and the like are changed linearly, but the position of the permanent magnet can be calculated by changing the output linearly and calculating the output. Further, in the present embodiment, the temperature compensating circuit R2 is arranged in parallel with a part of the magnetoresistive element R1, but the temperature compensating circuit R2 may be arranged in series with the magnetoresistive element R1.

[0035]

As is apparent from the above description, according to the air chuck with switch of the present invention, the position of the permanent magnet fixed to the piston is linearly measured by the magnetic linear scale, so that the object Then, it is possible to determine whether or not the air chuck is gripping the object by setting the corresponding piston position. Further, according to the magnetic linear scale of the present embodiment, the magnetoresistive element is formed with a constant width in the direction orthogonal to the moving direction of the permanent magnet, and the density linearly changes in the moving direction of the permanent magnet. The position of the permanent magnet can be detected linearly and accurately over a long range. In addition, since the magnetic linear scale can be manufactured with a narrow width, it is compact without taking up space. Further, since the magnetic linear scale has uniformity in the width direction, even if the magnetic linear scale laterally shifts with respect to the permanent magnet, the output change is small and the magnetic linear scale can be easily attached.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing the configuration of an air chuck with a switch that is an embodiment of the present invention.

FIG. 2 is a diagram showing a structure of a magnetic detector.

FIG. 3 is a conceptual diagram showing a configuration of a magnetic linear scale of the first embodiment.

FIG. 4 is a conceptual diagram showing a configuration of a magnetic linear scale according to a second embodiment.

FIG. 5 is a conceptual diagram showing a configuration of a magnetic linear scale according to a third embodiment.

FIG. 6 is a conceptual diagram showing a configuration of a magnetic linear scale according to a fourth embodiment.

FIG. 7 is a plan view showing the configuration of the magnetic linear scale of the first embodiment.

FIG. 8 is a partially enlarged view showing the details of the configuration of the magnetic linear scale of the first embodiment.

FIG. 9 is a plan view showing a configuration of a magnetic linear scale according to a second embodiment.

FIG. 10 is a partially enlarged view showing details of the configuration of the magnetic linear scale of the second embodiment.

FIG. 11 is a detection circuit diagram of the magnetic detector.

FIG. 12 is a diagram for explaining the operation of the detection circuit.

FIG. 13 is a data diagram showing a magnetoresistance change rate of a magnetoresistive element.

FIG. 14 is a diagram showing experimental data of the magnetic linear scale of the first embodiment.

FIG. 15 is a detection circuit diagram of a conventional magnetic detector.

FIG. 16 is a first explanatory diagram for explaining the operation of the conventional magnetic detector.

FIG. 17 is a second explanatory diagram for explaining the operation of the conventional magnetic detector.

FIG. 18 is a plan view showing the configuration of a conventional magnetic linear scale.

[Explanation of Codes] 11 Magnetic Detector 12 Cylinder Hole 13 Permanent Magnet 14 Piston 18 Rod 22 Chuck Claw 23 Magnetic Linear Scale 31 Detection Circuit R1 Magnetoresistive Element R2 Temperature Compensation Circuit

Claims (7)

[Claims] 1. An air chuck in which a piston is moved by the action of compressed air, and a pair of chuck claws are moved by a rod provided in the piston to grip an object to be gripped, the position of the piston being linear analog data. And a chuck grip detection means for detecting a grip state of the pair of chuck claws based on analog data output by the linear scale. 2. The linear scale according to claim 1, wherein the linear scale is formed of a vapor-deposited thin film of a ferromagnetic metal on a substrate, and is composed of a magnetoresistive element that exhibits a magnetoresistive effect. A magnetic linear scale having a constant width formed in a direction orthogonal to a moving direction of the permanent magnet attached to the piston, and a density linearly changing in the moving direction of the permanent magnet. Air chuck. 3. A linear scale that outputs the position of a piston that moves due to the action of compressed air as linear analog data, and an intermediate position detection that detects the intermediate position of the piston based on the analog data output by the linear scale. Means, the linear scale is formed of a vapor-deposited thin film of a ferromagnetic metal on a substrate, and is composed of a magnetoresistive element that exhibits a magnetoresistive effect, wherein the magnetoresistive element is attached to the piston permanently. An air cylinder with a switch, which is a magnetic linear scale which is formed with a constant width in a direction orthogonal to a moving direction of a magnet, and whose density linearly changes in a moving direction of the permanent magnet. 4. The switch according to claim 2, wherein the magnetoresistive element has the same line width, and the density is sequentially changed in a direction in which the permanent magnet moves. Air chuck with switch or air cylinder with switch. 5. The air chuck with a switch or the switch according to claim 2 or 3, wherein the magnetoresistive element sequentially changes a line width in a direction in which the permanent magnet moves. With air cylinder. 6. The device according to claim 2, wherein the magnetoresistive element sequentially changes a density of a pattern having a wide line width in a moving direction of the permanent magnet. Air chuck with switch or air cylinder with switch. 7. The air chuck with a switch according to claim 2, wherein the magnetoresistive element sequentially changes a line width and a density in a moving direction of the permanent magnet. Or air cylinder with switch.