JP3039828U - Magnetic sensor - Google Patents

Abstract

(57) Abstract: [PROBLEMS] To make a Hall effect type position sensor using a Hall element as an over-detector and an origin detector in a robot or a servo mechanism small and inexpensive. SOLUTION: A right-side over detection Hall element 2a and an origin detection Hall element 2b are arranged on a same substrate 6 with a predetermined gap A and B offset from each other to form a single sensor. 1 is a permanent magnet, 7 is a 4-core cable, 8 is an LED, 9
Is an IC circuit chip, and 10 is a case. The output signal of the hall element is derived as an external signal by the cable 7.

Description

[Detailed description of the invention]

[0001]

[Technical field to which the invention belongs]

 The present invention relates to a magnetic sensor, and more particularly, to an improvement in the arrangement structure of Hall elements suitable for detecting a movement range over and origin detection in a robot driving servo mechanism or the like.

[0002]

[Prior art]

 Most robots used in a wide range of fields and servo machines that move on linear coordinates use detectors for alarms when the movement range is exceeded or for servo stop. Furthermore, in order to detect the servo origin, a detector is installed inside the over detector.

[0003]

[Problems to be solved by the device]

 For example, a micro switch is used for the low-priced detector as described above, and one micro switch is arranged on each of the left and right sides of the moving range for over detection, and the convex for over detection is moved relative to this. For the origin detection, a micro switch is placed inside the over-detector to detect the origin, and the protrusion for relative origin detection is used to open and close it.

However, in the above configuration example, since the detectors are arranged in two rows, the configuration becomes large. In addition, spring fatigue in the micro switch, component wear, etc. are prone to malfunction, and since the operating point shifts, replacement maintenance is required and the operation reliability is poor.

As another low-priced detector, there is an example in which a reed switch is used. A reed switch is used instead of the micro switch for the over detection and the origin detection, and a magnet is used instead of the protrusion. Is used.

In this example, the reed switches arranged in two rows need to be arranged apart from each other in the detectors so as not to cause magnetic interference, and it is inevitable that the configuration becomes large. In addition, a malfunction such as a contact defect is likely to occur, which is problematic in terms of reliability.

Recently, hall effect type position sensors that combine a permanent magnet and a hall element have been applied to various mechanical devices, electric / electronic devices, automation devices, and the like. This Hall-effect type position sensor constructs a magnetic field generator by attaching a permanent magnet to the object whose position is to be detected, or constructs a magnetic field generator using the permanent magnet itself as the object to be detected. The magnetic field detection unit composed of a Hall element is configured to slide relative to the generation unit, and when the magnetic field generation unit and the magnetic field detection unit are close to each other, the Hall element of the magnetic field detection unit is The Hall effect is used to detect the magnetic field from the magnetic field generator and output an electrical signal to detect the position of the object to be detected.

As is well known as the Hall effect, as shown in FIG. 10, a Hall element made of a semiconductor thin film 40 such as InSb is used, and a current I is caused to flow in a certain direction of the semiconductor thin film 40. This is a phenomenon that when a magnetic field H is applied in a direction orthogonal to the direction of the current I, a Hall voltage Vh is generated in a direction orthogonal to both the current I and the magnetic field H. Proportional to the product of H. Therefore, by causing the Hall element to generate a magnetic field, it is possible to output the Hall voltage Vh, that is, an electric signal, according to the magnitude of the magnetic field, and by this, the position of the object to be detected is detected and the object is detected at this position. It is possible to perform necessary control operations such as stopping the detection body. A Hall-effect type position sensor configured with such a hall element as a magnetic field detection unit operates without contact with the object to be detected without having mechanical contacts such as the micro switch and reed switch, and is therefore reliable. Since it has the advantage that it is highly applicable, it has been widely applied.

An object of the present invention is to provide a magnetic sensor having a small size and a relatively low cost by using the Hall effect type position sensor as the over detection and original inspection output detector.

[0010]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, the magnetic sensor of the present invention comprises a magnetic field generating part composed of a permanent magnet and a Hall element or the like which moves relative to the magnetic field generating part and detects the magnetic field from the magnetic field generating part. In the magnetic sensor including the magnetic field detection unit, the magnetic field detection unit has at least two Hall elements arranged on the same substrate at a predetermined vertical and horizontal intervals, and output signals of the respective Hall elements. The gist is that it is configured to derive as an external signal.

In the above magnetic sensor, the two Hall elements may be connected to a common power source and may be connected to the outside by a four-core cable.

Further, the magnetic field generation unit has a length dimension smaller than that of the first permanent magnet and the first permanent magnet arranged with equal gaps on both sides along the moving direction of the first permanent magnet. It may be composed of a second permanent magnet and a third permanent magnet, and may be magnetized such that the polarities of the second permanent magnet and the third permanent magnet are opposite to the polarities of the first permanent magnet.

[0013]

[Embodiment of the invention]

 FIG. 1 is a block diagram showing an example of a Hall effect type position sensor. 1 is a magnetic field generating section made of a permanent magnet, 2 is a magnetic field generating section which slides in a magnetic flux direction 3 relative to the magnetic field generating section 1, and operates. It is a magnetic field detection unit including a Hall element 5 that detects the magnetic field from the magnetic field generation unit 1 while maintaining the distance h1. Reference numeral 4 denotes a circuit unit having a bias voltage applied to the output voltage of the Hall element 5 of the magnetic field detection unit 2 and a power source for supplying a current to be supplied to the Hall element 5 and a circuit for processing the output voltage, as will be described later. As described above, the Hall element 5 forming the magnetic field detecting unit 2 is a semiconductor thin film such as InSb.

Since the Hall effect type position sensor does not cause mutual interference with magnetism, for example, as shown in FIG. 2, in the magnetic field of the same permanent magnet 1a, the hall element 5a for over detection and the hall element for origin detection are detected. The element 5b can be arranged and used. Therefore, high-precision Hall elements 5a and 5b are arranged in a two-story structure in the same space and mounted for origin detection and over detection without mutual interference. However, even with such a two-story layout, the sensors are arranged in one row, but since the Hall elements are not arranged on the same substrate, the number of sensors is three and the height is also required. Also, in terms of the above, it is not possible to make the size small, and since each Hall element is on a separate substrate, two 3-core cables are required for the wiring, and the wiring cannot be simplified.

Therefore, in the present invention, as shown in FIG. 3, for example, the right-side over detection hall element 5a and the origin detection hall element 5b are arranged on the same substrate 6. Since the recent hall element chip parts 5a and 5b are extremely small, they are arranged on the same substrate 6 with a predetermined vertical and horizontal gaps A and B, and the respective output signals are led to the outside by the cable 7 as external signals. In this way, a two-step sensor is used. By changing the intervals A and B, for example, A = 1.5 mm and B = 3 mm, and changing the mounting direction of the Hall element, two steps can be used for different purposes. . In addition, 8 is an LED, 9 is a Hall element and an IC circuit chip for the LED 8, and 10 is a case. The LED 8 indicates the ON state of the hall element. For example, if a two-color light emitting LED is used, each LED can confirm the operating state.

[0016]

【Example】

 FIG. 4 shows an embodiment of the present invention, in which the sensor shown in FIG. 3 is incorporated in the case 10 of the magnetic field detector, and the case 10 is provided with a window 11 and a mounting screw hole 12. . The LED 8 is fitted in the window 11, and a step 13 is formed in the portion between the window 11 and the screw hole 12, and this step 13 is for preventing rotation at the time of mounting.

That is, as shown in FIG. 5, the side end portion of the L-shaped metal fitting 14 is brought into contact with the step 13 of the case 10 and screwed to the case 10, and is attached to the fixed side with the screw 15. Reference numeral 16 is a magnetic field generating portion which is adhered to the L-shaped metal fitting 17 and can be attached to the moving side by a screw 18. The magnetic field generation unit 16 may use a normal permanent magnet, but the use of a magnetic field generation unit as described below is effective in improving detection accuracy.

6 to 8 show a specific configuration example of the magnetic field generation unit 16, FIG. 6 is a plan view, FIG. 7 is a sectional view taken along line AB of FIG. 6, and FIG. It is a D sectional view. 26 is a first permanent magnet made of an anisotropic Ba ferrite magnet having a large coercive force, and 27 and 28 are equal gaps D on both sides along the sliding direction (magnetic flux direction) 23 of the first permanent magnet 26. (See FIG. 9), which are second and third permanent magnets that are smaller than the first permanent magnet and that are made of the same material as the first permanent magnet 26 and that are spaced apart from each other. Also, the polarities of the third permanent magnets 27 and 28 are magnetized so as to be opposite to the polarities of the first permanent magnet 26. As shown in FIG. 9, the lengths of the first, second, and third permanent magnets 26, 27, and 28 along the sliding direction 23 are L1, L2, and L3, respectively, and the height is H, Assuming that the width dimension in the vertical direction to the paper surface is W, L1 = 6 mm, L2 = L3 = 3 mm, H = 3 mm, W = 6 mm, D = 3 mm are set as an example. FIG. 9 shows the magnetic fluxes generated from the permanent magnets 26, 27, 28 by broken lines B1, B2, B3 ... And the characteristic curve of the Hall output (voltage) experimentally obtained by this magnetic field generation unit 16. Are indicated by solid lines C1, C2, C3 .... Here, an example is shown in which the magnetic field detection unit 22 is slid with respect to each of the permanent magnets 26, 27, 28 at a height position that maintains the operating distance h1. The horizontal axis (x axis) indicates the slide direction, and the vertical axis (y axis) indicates the height direction.

In FIG. 7, each of the permanent magnets 26, 27, 28 is housed in a non-magnetic case 29 such as plastic, and is integrally attached to a mounting plate 30 made of a non-magnetic material or a ferromagnetic material. The mounting plate 30 is provided with a positioning hole 31 in advance, and the permanent magnets 26, 27, 28 are bonded to each other with the projection 32 provided on the bottom of the non-magnetic case 29 positioned in the hole 31. It is integrated with the non-magnetic case 29 and the mounting plate 30 by the agent. Further, on the upper surface of the non-magnetic case 29, a groove 33 serving as a mark indicating the switching operation range is provided. As will be described later, the mounting plate 30 is preferably made of a ferromagnetic material such as mild steel due to its characteristics. The mounting plate 30 is provided with an elliptical mounting hole 34 along the sliding direction, and the mounting screw 35 is screwed into the mounting hole 34, whereby the mounting plate 30 is fixed to the object to be detected. This fixed position can be adjusted by sliding it along the mounting hole 34.

In FIG. 9, solid lines C1, C2, C3 ... Show characteristic curves in which the Hall output becomes 0 V, ± 0.1 V, ± 0.2 V, and the magnetic fluxes of broken lines B1, B2, B3 ... It is estimated and plotted from the characteristic curve group of the video output. The characteristic curves and magnetic fluxes are shown symmetrically around the central portion CL of the first permanent magnet 26. Since the Hall element 5 surface of the magnetic field detection unit 2 that is close to and above each of the permanent magnets 26, 27, and 28 with the operating distance h1 is held perpendicular to the y axis, the magnetic flux density B in the vertical direction is Hall output proportional to is obtained. The magnetic flux density B in the vertical direction must be 0 on the characteristic curve of Hall output 0V. The broken lines B1, B2, B3, ... Denoting the magnetic flux are plotted so as to be almost the same. The magnetic flux also exists in the downward direction of the x-axis, but it is omitted.

When the magnetic field detection unit 22 is slid while keeping the operating distance h1, if the magnetic field detection unit 22 is on the far left side of the origin of x = 0, the vertical magnetic flux density B is 0. The output becomes 0V. When the magnetic field detector 22 is slid to the right, Hall outputs of -0.2V, -0.1V, 0V, 0.1V and 0.2V are generated at points P1, P2, P3, P4 and P5, respectively. To do. Further, when it is slid to the right, Hall outputs of 0.2V, 0.1V, 0V, -0.1V and -0.2V are generated at points Q1, Q2, Q3, Q4 and Q5, respectively. Between P5 and Q1, a hall output of 0.2V or higher is generated, reaching a maximum of 0.3V and saturated.

Here, as an actual usage method, a method in which the Hall output performs a switching operation at 0 V must be avoided because the operation becomes unstable. This is to prevent the switching operation because the Hall output is 0 even when the magnetic field detection unit 22 is on the far left side of the y-axis, so that the switching operation is prevented. Therefore, as described above, it is better to apply a bias voltage to the Hall element so that the switching operation is performed when the sum of the bias voltage and the Hall output becomes zero. As a specific example, if a bias voltage of -0.05 V is applied to the Hall output, the V curves of solid lines C3 and C6 in FIG. 9 are -0.05 V curves, and the solid curves C2 and C7 of -0. The 1V curve becomes a -0.15V curve. In this way, the output of all curves is shifted by -0.05V. Therefore, the 0.05V curve of the broken lines C10 and C20 becomes a 0V curve.

As described above, the operation with the bias voltage applied is as follows. That is, when the magnetic field detection unit 22 is located far to the left of the y-axis, a bias voltage of -0.05V is applied to the Hall output of 0V, so that the total output becomes -0.05V. Next, when the magnetic field generation unit 16 slides to the point P1, the total output in this case becomes -0.25V by applying -0.05V to -0.2V of C1. Similarly, the total output when sliding to point P2 is -0.15V, and the total output when sliding to point P3 is -0.05V, which is the same as the intersection point with the 0.05V curve of broken line C10. Then, the total output becomes 0V, the switching operation is performed, and the control signal is output. The magnetic field detector 22 is slid to the right, and all outputs are positive until the intersection of the broken line C20 after passing the points Q1 and Q2, and the switching operation is maintained. When it slides further to the right and reaches points Q3, Q4 and Q5, all outputs become negative and the switching operation is canceled.

As a result, as long as the magnetic field generation unit 16 slides within the range of the broken lines C10 and C20, the switching operation is retained, so that a wide switching operation width can be secured. By thus ensuring a wide switching operation width, the position sensor can be reliably operated, and the object to be detected can be stopped at a predetermined position. In this respect, when the switching operation width is narrow, the position sensor cannot reliably operate, and it becomes difficult to stop the detected object at a predetermined position. Further, since the 0.05V curves of the broken lines C10 and C20 can be made to have a shape close to an ideal that is almost vertical, even if the magnetic field detector 22 changes in the y-axis direction, that is, the magnetic field generator 16 and the magnetic field Even if the operating distance h1 with the detection unit 22 changes, the deviation of the detection position in the sliding direction can be suppressed to be small, so that the detection accuracy can be improved. As a result, the working distance h1 can be increased. In this respect, when the permanent magnets forming the magnetic field generating unit are closely attached together without providing a gap as in the conventional case, the 0V curve is greatly inclined to the outside, so it is assumed that an appropriate bias voltage is applied. However, since it is difficult to make the 0V curve into an ideal shape close to vertical, it is not possible to increase the working distance.

The reason why the 0V curve can be idealized as described above is that the 0V curve of the solid lines C3 and C6 in FIG. 9 is slightly inclined outward. This is because the length dimensions L2 and L3 of the second and third permanent magnets 27 and 28 are set smaller than the length dimension L1 of the first permanent magnet 26, and the gap D is provided. . In this embodiment, when the current directions of the Hall elements of the magnetic field detector 22 are reversed, the signs of the characteristic curves are all reversed. In this case, + 0.05V is applied as the bias voltage. As a result, the total output output in the switching operation range between the solid lines C10 and C20 becomes negative.

[0026]

[Effect of the invention]

 As explained above, according to the present invention, the following practically excellent effects can be obtained. (1) Since two Hall elements are provided on the same substrate to make one sensor, it is advantageous in terms of height without stacking in two stages, and is more effective for miniaturization. is there. (2) Two Hall elements are built into one case, the power source is shared in terms of circuit, and the wiring can be completed with one 4-core cable, which is very easy. (3) The two-step operating distance determined by A and B is not inconvenient even if it is fixed in general, and for example, it can sufficiently meet the demand for a step interval of 2 to 2.5 mm. (4) The circuits corresponding to the two sets of Hall elements have many common parts, and the LED requires only one two-color light emitting type, so the size of the case for housing the Hall elements is sufficient even if it is not large.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an example of a Hall effect type position sensor.

FIG. 2 is a schematic diagram showing an arrangement example of hall elements for over detection and origin detection.

FIG. 3 is a schematic diagram showing the basic structure of the present invention.

FIG. 4 is a schematic view showing an embodiment of the present invention.

FIG. 5 is a side view showing the embodiment.

FIG. 6 is a plan view showing the configuration of a magnetic field generation unit of the Hall effect type position sensor of this embodiment.

7 is a cross-sectional view taken along the line AB of FIG.

8 is a cross-sectional view taken along the line C-D in FIG.

FIG. 9 is a characteristic diagram of Hall output obtained by the Hall effect type position sensor of the present embodiment.

FIG. 10 is a schematic diagram illustrating a Hall effect.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 magnetic field generation part 2 magnetic field detection part 3 slide direction (magnetic flux direction) 4 circuit part 5 hall element 26 first permanent magnet 27 second permanent magnet 28 third permanent magnet 29 non-magnetic case 30 mounting plate 34 mounting hole

Claims (3)

[Utility model registration claims] 1. A magnetic device comprising a magnetic field generation unit composed of a permanent magnet and a magnetic field detection unit composed of a Hall element or the like that moves relative to the magnetic field generation unit and detects a magnetic field from the magnetic field generation unit. In the sensor, in the magnetic field detection unit, at least two Hall elements are arranged on the same substrate vertically and horizontally with a predetermined gap, and the output signal of each Hall element is derived as an external signal. Characteristic magnetic sensor. 2. The magnetic sensor according to claim 1, wherein the two Hall elements are connected to a common power source and are connected to the outside by a four-core cable. 3. The magnetic field generator includes a first permanent magnet,
The first permanent magnet is composed of second and third permanent magnets having a smaller length dimension than the first permanent magnet, which are arranged with equal gaps on both sides along the moving direction of the first permanent magnet. The magnetic sensor according to claim 1, wherein the second and third permanent magnets are magnetized so that the polarities thereof are opposite to each other.