This application contains subject matter related to and claims the benefit of Japanese Patent Application No. 2013-147566 filed on Jul. 16, 2013, the entire contents of which is incorporated herein by reference.
1. Field of the Disclosure
The present Disclosure relates to a position detection device, and more particularly, to a magnetic position detection device that detects an object to be detected by a magnetic change.
2. Description of the Related Art
Conventional position detection devices, which detect the approach of an object to be detected to a predetermined position by a magnetic change are used for various purposes, such as an operation directly relating to driving of a steering wheel, an accelerator, a brake, and the like, the opening and closing of a door or a window, and the detection of the position of a seat, as the control of, for example, an automobile or the like is changed into a control using electronics. For this reason, the size of the position detection device is required to be reduced so that the position detection device can be installed at a place according to a purpose.
Japanese Unexamined Utility Model Registration Application Publication No. 62-120239 (first related art example) discloses a proximity sensor (position detection device) 900 shown in
However, in the proximity sensor 900 disclosed in Japanese Unexamined Utility Model Registration Application Publication No. 62-120239, the permanent magnets 909 and 910 are disposed on both sides of the magneto-electric transducer 904 so as to be lined up on the surface (upper surface) of the circuit board 903 where the magneto-electric transducer (detection unit) 904 is mounted. Accordingly, there has been a problem in that a projected area of the proximity sensor is large. Further, since the upper surface of the board becomes thick and a distance between the detection unit and the object to be detected cannot be smaller than the height of the magnet, there has been a problem in that a detection range is narrowed.
These and other drawbacks exist.
Embodiments of the present disclosure provide a position detection device that can make a projected area small without narrowing a detection range.
According to an example embodiment, a position detection device includes: a detection unit configured to detect the approach of an object to be detected in a space to be detected; a spacer member; and a first magnet and a second magnet configured to generate a magnetic field in the space to be detected. The detection unit is disposed at a position that faces the first magnet with the spacer member interposed therebetween, the first magnet is disposed between the spacer member and the second magnet so that a polarity of the first magnet corresponds to a polarity of the second magnet opposite to the polarity of the first magnet, a magnetic force generated from the second magnet reaches a position distant from the detection unit in the space to be detected as compared to a magnetic force generated from the first magnet, a magnetic field is generated by composition of the magnetic force that is generated from the first magnet and the magnetic force that is generated from the second magnet, and the detection unit detects the approach of the object to be detected by detecting a change of a magnetic field that occurs when an influence of the magnetic force generated from the second magnet is changed by the object to be detected moving in the space to be detected.
Since the magnets are disposed on one side of the detection unit so as to overlap with the detection unit, it is possible to make a projected area of the position detection device small. Further, since only the detection unit is present on the surface of the spacer member facing the detection unit, a distance between the detection unit and the object to be detected can be made short. Accordingly, a detection range is not narrowed. Therefore, it is possible to provide a position detection device that can make a projected area small without narrowing a detection range.
Furthermore, a length of the first magnet in a magnetization direction may be shorter than a length of the second magnet in the magnetization direction and the first and second magnets may be disposed so as to come into contact with each other.
Since the length of the first magnet in the magnetization direction is shorter than the length of the second magnet in the magnetization direction, a magnetic force generated from a portion of the second magnet, which does not overlap with the first magnet, reaches a distant position.
Moreover, the second magnet may be formed so that two magnets are connected to each other with a magnetic member interposed therebetween.
Since the second magnet is formed so that the magnetic member more inexpensive than a magnet is interposed between the two magnets, small magnets can be used. For this reason, since it is possible to make the second magnet inexpensive while maintaining the size of the second magnet, it is possible to reduce the cost of the position detection device.
The following description is intended to convey a thorough understanding of the embodiments described by providing a number of specific embodiments and details involving a position detection device. It should be appreciated, however, that the present invention is not limited to these specific embodiments and details, which are exemplary only. It is further understood that one possessing ordinary skill in the art, in light of known systems and methods, would appreciate the use of the invention for its intended purposes and benefits in any number of alternative embodiments, depending on specific design and other needs.
The structure of the position detection device 100 according to this embodiment will be described first with reference to
As shown in
When the position detection device 100 is used, the position detection device 100 may be disposed so that the detection surface 10c faces a space to be detected. The position detection device 100 may detect that an object 500 to be detected moving in a space to be detected approaches the detection surface 10c. A plurality of connection electrodes 11 may be disposed in the connection portion 10d. Power, which is required for the operation of the position detection device 100, may be supplied and detection signals, which may be an output of the position detection device 100, are output through the connection electrodes 11.
As shown in
The detection unit 1 may be a magneto-electric transducer that uses a magnetoresistive element and the like. The detection unit 1 may convert the change of the state of a magnetic force, which may be applied to the detection unit 1, into an electric signal and outputs the electric signal.
The spacer member 2 may be a printed wiring board made of glass epoxy or the like, and a copper foil pattern (not shown) may be formed on a Z1-side surface and a Z2-side surface of the spacer member 2 shown in
The first magnet 3 may have the shape of a rectangular plate as shown in
The second magnet 4 may have the shape of a rectangular plate as shown in
A relationship between the shape of the first magnet 3 and the shape of the second magnet 4 and a relationship between magnetic forces applied to the first and second magnets 3 and 4 may be appropriately adjusted and set so that a desired magnetic field can be generated.
The frame 5 may be made of a non-magnetic synthetic resin material, for example. As shown in
As shown in
The connection electrode 11 may be made of a non-magnetic conductive material, such as copper or phosphor bronze. As shown in
As shown in
The second magnet 4 may be positioned on the inner bottom surface of the base part 10a, which faces the detection surface 10c of the housing 10, by the walls 10g that are provided so as to surround the central portion of the inner bottom surface from every side. The second magnet 4 may be fixed inside the walls 10g in the Y1-Y2 direction shown in
When the positioning portions 5b formed on both sides of the frame 5 (in the Y1-Y2 direction of
The first magnet 3 may be positioned by the rectangular opening 5a formed at the central portion of the frame 5. The first magnet 3 may be disposed and fixed inside the opening 5a in an X1-X2 direction shown in
When the first protrusions 10f, which have a columnar shape and are formed at four corners on the inner bottom surface of the base part 10a facing the detection surface 10c of the housing 10, are inserted into the positioning holes 2b, the spacer member 2 is positioned. The spacer member 2 may be disposed and fixed so as to come into contact with the upper surface (Z1-side surface) of the first magnet 3. For this reason, the detection unit 1 may be disposed close to the detection surface 10c and a space to be detected may be formed above the upper side (Z1 side) of the detection unit 1. Further, the terminal portions 11b of the connection electrodes 11 may be inserted into the grooves 10e formed in the base part 10a of the housing 10, and may be fixed so as to be exposed to the inside of the connection portion 10d.
As shown in
Next, the operation of the position detection device 100 will be described with reference to
The magnetic force, which may be generated by the first magnet 3, can be shown as in
The magnetic force, which may be generated by the second magnet 4, can be shown as in
Accordingly, the magnetic forces applied to the detection unit 1 can be shown as in
When the object 500 to be detected, which is formed of a magnetic body, moves and approaches the space to be detected, the magnetic force, which is generated from the second magnet 4 and reaches a position distant from the detection unit 1 as compared to the magnetic force generated from the first magnet 3, may be transmitted through the object 500 that is to be detected and has high magnetic permeability, as shown in
For this reason, since the magnetic force (B2) generated from the second magnet 4 is reduced, the direction of the magnetic force, which is obtained by the composition of the magnetic force generated from the first magnet 3 and the magnetic force generated from the second magnet 4, may be reversed from the initial state. As a result, the magnetic force applied to the detection unit 1 may be directed to the Y2 side in the Y1-Y2 direction. Further, the strength of the magnetic field becomes B3′ (=B1−B2).
The influence of the magnetic force, which is generated from the second magnet 4, on the detection unit 1 is changed by the approach of the object 500 to be detected that is formed of a magnetic body, and the detection unit 1 may detect the change of the direction of the magnetic field applied to the detection unit 1, converts the change of the direction of the magnetic field into an electric signal, and outputs the electric signal. Accordingly, the detection unit 1 can detect the approach of the object 500 to be detected.
Since the first and second magnets 3 and 4 are disposed below the detection unit 1 (Z2 side of the detection unit 1) so as to overlap with the detection unit 1, it is possible to detect the approach of the object 500 to be detected even though the object 500 to be detected approaches in the X1-X2 direction, approaches in the Y1-Y2 direction, or approaches in the Z1 direction.
When the object 500 to be detected, which is formed of a magnetic body, moves and becomes distant from the space to be detected, the position detection device 100 may return to the initial state shown in
The influence of the magnetic force, which is generated from the second magnet 4, on the detection unit 1 may be changed when the object 500 to be detected formed of a magnetic body becomes distant from the detection unit 1, and the detection unit 1 detects the change of the direction of the magnetic field applied to the detection unit 1, converts the change of the direction of the magnetic field into an electric signal, and outputs the electric signal. Accordingly, the detection unit 1 can detect that the object 500 to be detected becomes distant.
In the position detection device 100 according to this embodiment, the detection unit 1 may be disposed at a position that faces the first magnet 3 with the spacer member 2 interposed therebetween; the first magnet 3 may be disposed between the spacer member 2 and the second magnet 4 so that the polarity of the first magnet 3 corresponds to the polarity of the second magnet 4 opposite to the polarity of the first magnet 3; the magnetic force generated from the second magnet 4 may reach a position, which is distant from the detection unit 1 in the space to be detected as compared to the magnetic force generated from the first magnet 3; the magnetic field, which is obtained by the composition of the magnetic force generated from the first magnet 3 and the magnetic force generated from the second magnet 4, may be changed by the approach of the object 500 to be detected moving in the space to be detected; and the object 500 to be detected is detected from the change of the magnetic field.
For this reason, since the first and second magnets 3 and 4 are disposed on one side of the detection unit 1 so as to overlap with the detection unit 1, a projected area of the position detection device can be made small. Further, since only the detection unit 1 is present on the surface of the spacer member 2 facing the detection unit 1, a distance between the detection unit 1 and the object 500 to be detected can be made short. Accordingly, a detection range is not narrowed. Therefore, it is possible to provide a position detection device that can make a projected area small without narrowing a detection range.
Furthermore, in the position detection device 100 according to this embodiment, the length of the first magnet 3 in the magnetization direction may be shorter than the length of the second magnet 4 in the magnetization direction and the first and second magnets 3 and 4 may be disposed so as to come into contact with each other.
Accordingly, since the length of the first magnet 3 in the magnetization direction is shorter than the length of the second magnet 4 in the magnetization direction, a magnetic force generated from a portion of the second magnet 4, which does not overlap with the first magnet 3, reaches a distant position.
According to the position detection device 100 of this embodiment, it is possible to provide a position detection device that can make a projected area small without narrowing a detection range as described above.
The position detection device 100 according to the embodiment of the invention has been specifically described as described above, but the invention is not limited to the embodiment and may be variously modified without departing from the gist. For example, the invention may have the following modifications, and these modifications are also included in the scope of the invention.
(1) An example in which the second magnet is formed of one magnet having the shape of a rectangular plate has been described in this embodiment. However, as shown in
(2) An example in which the position detection device 100 includes the housing 10 has been described in this embodiment. However, the housing may be omitted according to the use of the position detection device 100. Further, the shape of the housing may also be appropriately modified according to the use of the position detection device 100 or a place in which the position detection device 100 is to be installed.
It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and alterations may occur depending on design requirements and other factors insofar as they are within the scope of the appended claims of the equivalents thereof.
Accordingly, the embodiments of the present inventions are not to be limited in scope by the specific embodiments described herein. Further, although some of the embodiments of the present disclosure have been described herein in the context of a particular implementation in a particular environment for a particular purpose, those of ordinary skill in the art should recognize that its usefulness is not limited thereto and that the embodiments of the present inventions can be beneficially implemented in any number of environments for any number of purposes. Accordingly, the claims set forth below should be construed in view of the full breadth and spirit of the embodiments of the present inventions as disclosed herein. While the foregoing description includes many details and specificities, it is to be understood that these have been included for purposes of explanation only, and are not to be interpreted as limitations of the invention. Many modifications to the embodiments described above can be made without departing from the spirit and scope of the invention.
Number | Date | Country | Kind |
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2013-147566 | Jul 2013 | JP | national |