JP2008076193A - Position detector, optical system with position detector, and imaging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a position detector suited for miniaturization and thinning with the distance between a magnetic flux detection means and a magnet, shorter than that in the past while maintaining a position detecting function of high accuracy equal to that in the past. <P>SOLUTION: The position detector detecting a change in position correspondingly to a change in magnetic flux comprises the magnet and a plurality of magnetic flux detection means. The magnet is made to include a line connecting at least two of the detection means on a magnetic wall surface of the magnet and the moving direction of the magnet is made to exist on the wall surface. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a position detection device using a magnet and a magnetic sensor, an optical system having the position detection device, and an imaging device.

  In recent years, various sensors have been used everywhere.

  For example, as described in Patent Document 1 and Patent Document 2, when a camera shake occurs in a digital video camera or a digital still camera, a camera shake correction device that detects and corrects a lens position or an optical system that performs automatic focus adjustment In the lens position detection apparatus, a sensor having a function of instantaneously performing highly accurate position detection is required, and at the same time, downsizing of the entire position detection apparatus is strongly demanded. In the mobile phone market and the like, there are many terminals equipped with a mobile camera having a solid-state image sensor such as a CCD. In the optical system applied to the mobile camera, the position detection device is further downsized. Is required.

  In order to satisfy the above requirements, the position detection of the optical lens or the like is performed by counting the driving step pulses of the stepping motor without using a sensor in the position detection device such as the optical lens as described in Patent Document 2. In some cases, the position detection device is made smaller by detecting the position of an optical lens or the like using a Hall sensor (magnetic sensor pair) as in Patent Document 3. FIG. 1 shows an example of a position detection device using such a hall sensor. In FIG. 1, the position of the variable power lens 103 to which the magnet 101 is attached is detected by the Hall sensors 102 a and 102 b inside the video camera 100, and a signal including information on the position of the variable power lens from the Hall sensor is received by the amplifier 109. And transmitted to the processing circuit 107 via the A / D converter 110. Then, a signal is sent from the processing circuit 107 to the driving circuit 108, and the driving circuit 108 controls the motor 106, whereby the position of the variable magnification lens is controlled between the fixed lens 104 and the fixed lens 105.

JP 2002-229090 A Japanese Patent Laid-Open No. 06-014231 JP-A-2005-331399 JP 2004-348173 A Japanese Patent Application No. 2005-364090

  However, the position detection device that counts the stepping motor driving step pulses as described in Patent Document 2 has a problem in that it cannot detect the position with high accuracy due to the stepping motor stepping out. Furthermore, in digital video cameras and the like, it is also regarded as a problem that the driving sound of the stepping motor is recorded as audio noise. In addition, since the stepping motor is larger than other driving sources, there is a problem in that downsizing of the entire device is hindered.

  In addition, in the method of detecting the position of the optical lens with the configuration described in FIG. 1 of Patent Document 3, the position of the lens can be detected with high accuracy, but in order to obtain a desired signal from the magnetic flux detection means. Therefore, a certain distance must be maintained between the magnet and the magnetic flux detection means, which has been regarded as a problem that hinders further downsizing and thinning.

  The present invention has been made in view of such problems, and the object of the present invention is to maintain a highly accurate position detection function equivalent to that of the prior art, and between the magnetic flux detection means and the magnet as compared with the prior art. It is an object of the present invention to provide a position detection device that can reduce the distance and is suitable for downsizing and thinning.

  In order to solve the above-mentioned problems, claim 1 is a position detection device comprising a magnet attached to an object whose position is to be detected and two magnetic flux detection means for detecting a change in magnetic flux due to relative movement of the magnet. The magnetic wall surface of the magnet includes a straight line connecting the two magnetic flux detection means, and the relative movement direction of the magnet with respect to the magnetic flux detection means is parallel to the magnetic wall surface.

  A second aspect of the present invention is characterized in that, in the first aspect of the invention, the magnetic flux detecting means can detect a magnetic flux component parallel to the magnetizing direction of the magnet.

  A third aspect of the present invention is characterized in that, in the invention of any one of the first and second aspects, the magnetic flux detecting means is a Hall sensor.

  A fourth aspect of the present invention is an optical system using the invention according to any one of the first to third aspects.

  An image pickup apparatus according to a fifth aspect uses the optical system according to the fourth aspect.

  The above means will be described in detail with reference to FIG. FIG. 2 shows a basic configuration of the position detection apparatus of the present invention. That is, the position detection device of the present invention includes the magnet 202, the magnetic flux detection means 210a and 210b of the magnet 202, and the amplifier 206 and the A / D converter 207 for transmitting signals from the magnetic flux detection means 210a and 210b to the processing circuit 208. , And a drive circuit 209 that drives the moving part having the magnet 202 in the direction of the arrow 212 in accordance with the signal transmitted from the processing circuit 208. The magnet 202 has a center of gravity 201 and a domain wall 203, a surface including the domain wall 203 is referred to as a magnetic wall surface 204, and a direction perpendicular to the magnetic wall surface 204 is referred to as a magnetization direction 211. Hereinafter, these components will be described.

  A magnet is a substance that stores energy in the form of magnetostatic energy, and is a magnetic material that retains residual magnetization once magnetized. Ferrite, alnico, rare earth, etc. are used. These magnets only need to have geometrically symmetrical planes in which N poles and S poles are respectively single poled. An example of a specific shape is the magnet 202 in FIG. The magnet only needs to have a geometric symmetry plane, and is not limited to the shape of the magnet 202 in FIG.

  The domain wall exists at the boundary between the S pole and the N pole when unipolar magnetization is performed as in the present invention. The magnetization direction and the plane including the domain wall are orthogonal to each other.

  The domain wall includes a domain wall in a plane that extends the domain wall to infinity. When the magnet moves, the magnetic wall surface exists at each position. In the present invention, as shown in FIG. 2, the magnet 202 moves on the straight line 205 connecting the magnetic detection means 210a and 210b. Since it moves in a direction parallel to the straight line 205, the magnetic wall surface 204 is uniquely determined.

  The relative movement of the magnet with respect to the magnetic flux detection means refers to the relative movement of the center of gravity of the magnet with respect to the magnetic flux detection means. Since the movement is relative, the magnet may move or the magnetic flux detection means may move.

  The magnetic flux detection means is a Hall sensor, a magnetoresistive effect element, a magneto-impedance element, various other magnetic sensors, and combinations thereof, and may include peripheral circuits such as drive and processing circuits.

  As a Hall sensor, a Hall sensor made of a compound semiconductor such as GaAs, InAs, or InSb that does not use a magnetic chip for performing magnetic amplification, or a Hall sensor made of an IV group semiconductor such as Si or Ge is used. Can do. Of course, a combination of a plurality of the above materials may be used. A member for performing magnetic amplification such as a magnetic chip has a magnetic hysteresis and may cause a decrease in detection accuracy of the relative position of the magnet. However, in applications where detection accuracy is not so required, a magnetic chip is used. There is no problem with using the hall sensor.

  The straight line connecting the magnetic flux detection means is a straight line connecting the centers of the magnetic sensitive surfaces that detect the magnetic flux of each magnetic flux detection means.

  The position detection device is a device including a magnet that is a magnetic flux generation source, a plurality of magnetic flux detection means, and peripheral circuits such as drive and processing circuits. Although FIG. 2 shows the amplifier 206 and the A / D converter 207, these components may not be necessary if the output of the magnetic flux detection means is sufficiently large.

  The optical system includes components such as a lens group, an actuator, and a CCD that are used in an imaging device such as a digital video camera and a digital still camera, a projection device such as a projector, and an optical pickup used in ODD and the like. . What has been described above is merely an example, and the present invention is not limited thereto.

  An imaging device is a device that can record or save video such as a digital video camera or a digital still camera. What has been described above is merely an example, and the present invention is not limited thereto.

  According to the present invention, it is possible to reduce the distance between the magnetic flux detecting means and the magnet as compared with the conventional position detection while maintaining a highly accurate position detection function equivalent to the conventional position detection, which is suitable for downsizing and thinning. A device can be provided.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
<Embodiment 1>
A schematic configuration of the position detection device will be described with reference to FIGS. 3 and 4. In the position detection device shown in FIG. 3, a magnet 301 (magnet width W, magnet length L, magnet height H) attached to a moving object is fixed, such as the device main body. A relative position with respect to the Hall sensors S1 and S2 attached to the object is detected. Here, the distance between the line segment connecting the first hall sensor S1 and the second hall sensor S2 is indicated by reference sign SL. The distance between the center of the magnetic sensitive surfaces of the hall sensors S1 and S2 and the magnet lower surface is indicated by reference numeral SMD. Further, the moving range of the center of the magnet is indicated by the symbol ST.

  The magnet 301 is a rectangular parallelepiped having a width W [mm], a height H [mm], and a length L [mm], and is monopolarly magnetized in the Y-axis direction. In FIG. 3, the X axis and the Z axis are directions parallel to the magnetic wall surface, and the Y axis is a direction perpendicular to the magnetic wall surface. Here, the Z-axis is a direction perpendicular to the substrate surface from the magnet toward the substrate surface. The domain wall of the magnet 301 is orthogonal to the Y-axis direction, and the domain wall is located at the midpoint of the width W of the magnet 301. The X axis is a direction parallel to the moving direction 303 of the magnet 301, and the Y axis is a direction perpendicular to the moving direction 303 of the magnet 301. In the following Embodiment 1 and Embodiment 2, the magnets are all neodymium sintered magnets, and the residual magnetic flux density is 1200 mT (value of a general neodymium sintered magnet). The following is an example of the position detection device according to the present invention, and the present invention is not limited to this.

  In the first and second embodiments described below, the first hall sensor S1 and the second hall sensor S2 are mounted on the substrate 304 with a predetermined distance SL, and the magnet 301 is mounted on the hall sensors S1, S2. It arrange | positions so that it may oppose. At this time, the magnet 301 is disposed so that the magnetic wall surface of the magnet 301 (the surface including the magnetic wall 302 of the magnet 301) includes a straight line connecting the first and second Hall sensors. The direction of the magnetic flux detectable by the first and second Hall sensors S1 and S2 is a direction parallel to the magnetizing direction of the magnet (Y-axis direction). The movement direction 303 of the magnet 301 is a direction parallel to the magnetic wall surface (X-axis direction).

  The signals from the hall sensors S1 and S2 are transmitted to the processing circuit 307 via the amplifier 305 and the A / D converter 306, and the moving part having the magnet 301 is moved according to the signal transmitted from the processing circuit 307. The drive circuit 308 connected to the processing circuit 307 is driven in the direction of the arrow 303 in FIG.

  Although FIG. 3 shows the amplifier 305 and the A / D converter 306, when the output of the magnetic flux detection means is sufficiently large, these components may not be necessary.

  In addition, FIG. 4 shows the movement range ST of the center of the magnet 301, the left end 402 where the magnet 301 moves, the right end 403 where the magnet 301 moves, and the magnet 301 located at the center with respect to the Hall sensors S1 and S2. The center position 401 of the magnet 301, the centers 404a and 404b of the magnetic sensitive surfaces of the hall sensors S1 and S2, and the distance SMD between the centers 404a and 404b of the magnetic sensitive surfaces and the lower surface of the magnet 301 are shown.

  Next, a procedure for obtaining the position of the magnet 301 from the outputs of the hall sensors S1 and S2 will be described with reference to FIG. FIG. 5 shows the movement range 501 of the center of the magnet 301, the left end 503 to which the magnet 301 moves, the right end 504 to which the magnet 301 moves, and the magnet when the magnet 301 is located at the center with respect to the Hall sensors S1 and S2. A center position 502 of 301 is shown. In this configuration, two hall sensors are used. The output of each Hall sensor S1, S2 when the magnet moves from end to end in the movable range differs depending on the sensor position. When the hall sensors S1 and S2 are arranged at optimal positions with respect to the magnet 301, an output signal from the hall sensor S1 is an output signal A, and an output signal from the hall sensor S2 is an output signal B. At this time, when the output signals A and B are calculated as (output signal A−output signal B) / (output signal A + output signal B) by the processing circuit 307 shown in FIG. A close signal can be obtained. At this time, depending on the arrangement of the magnet 301 and the hall sensors S1 and S2, a signal close to linear with respect to the movement of the magnet can be obtained by calculating (output signal A−output signal B). Therefore, depending on the arrangement relationship, (output signal A-output signal B) can be used when calculating the position of the magnet.

  In FIG. 5, when the left end of the magnet is positioned at the left end 503 of the movable range, the hall sensors S1 and S2 each output a value indicated by Δ in the middle graph. The output is calculated by the processing circuit 307, and the linearized signal Δ shown in the lower stage is output. Next, the same processing is performed when the right end of the magnet 301 is positioned at the right end 504 of the movable range. The output signals A and B and the linearized signal when the magnet is positioned at the right end are indicated by □ in the middle and lower graphs, respectively. A linear form is defined by linearly interpolating the two points of the linearization signal Δ and the linearization signal □. When the magnet actually moves, the position of the magnet is calculated by applying this linear form.

  Since the output signal A and the output signal B are proportional to the magnetic flux density, a magnetic simulation by a computer for static magnetic field analysis is performed, and the magnetic flux density is made to correspond to the Hall sensor signal in FIG. 5 to calculate the detection resolution of the position detection device. Went.

  Computer simulations of static magnetic field analysis can use either differential equation methods (finite element method, difference method, etc.) or integral equation methods (boundary element method, magnetic moment method, etc.) as long as the magnetic field H [A / m] can be obtained. You may use.

  First, a case where a position of 2 mm (± 1 mm) is detected with a resolution of 5 μm in a wide temperature range will be described. A design example of the optimum value of the parameter of each component in FIGS.

  The length L of the cuboid magnet is 2.5 mm, the width W of the cuboid magnet is 2.9 mm, and the height of the cuboid magnet is H = 0.9 mm.

  Further, the distance SMD = 1.2 mm from the plane (the bottom surface of the magnet) facing the Hall sensors S1, S2 of the rectangular parallelepiped magnet to the center of the magnetic sensitive surface of the Hall sensors S1, S2, the magnetic sensitive surface of the first Hall sensor S1. The distance SL between the center and the center of the magnetic sensitive surface of the second Hall sensor S2 is set to 0.8 mm. The distance (H + SMD) from the center of the magnetosensitive surface of the Hall sensors S1, S2 to the upper surface of the magnet is 2.1 mm.

  At the time of the above design, as shown in FIG. 16, rather than mounting the Hall sensors S1 and S2 separately on the mounting board, all the Hall sensors S1 and S2 are mounted in one mold package 1602 in which the electrodes 1601 are installed. You may do it. In this case, the arrangement errors of the hall sensors S1 and S2 are reduced, which can contribute to the high accuracy of the position detection device. Further, for example, it is possible to provide all the hall sensors S1 and S2 on the Si substrate. Therefore, the hall sensor S1 and the hall sensor S2 may be enclosed in one package.

  FIGS. 11-13 shows the change of the magnetic flux density with respect to the moving distance of a rectangular parallelepiped magnet.

  11 shows the magnetic flux density change 11 at the position of the first Hall sensor S1 with respect to the moving distance of the magnet. FIG. 12 shows the magnetic flux density change 12 at the position of the second Hall sensor S2 with respect to the moving distance of the magnet. Represents a difference 13 in magnetic flux density change obtained by subtracting the magnetic flux density at the position of the first Hall sensor S1 from the magnetic flux density at the position of the second Hall sensor S2 with respect to the moving distance of the magnet.

  Thereby, the difference magnetic flux density obtained by subtracting the magnetic flux density at the position of the first Hall sensor S1 from the magnetic flux density at the position of the second Hall sensor S2 with respect to the movement of the magnet may change in a curve close to linear. I understand.

  Since the output voltage of the hall sensor is proportional to the magnitude of the magnetic flux density, the difference value between the output voltage Va of the first hall sensor S1 and the output voltage Vb of the second hall sensor S2 is relative to the moving distance of the magnet. The output characteristics are almost linear.

  FIG. 14 shows a difference value (Va−Vb) between the output voltage Va of the hall sensor S1 and the output voltage Vb of the hall sensor S2 with respect to the movement of the rectangular parallelepiped magnet in the configuration example with the above parameters. The value obtained by dividing the value divided by (Va + Vb) from the magnetic simulation value is shown. FIG. 14B is an enlarged view of the region 22 in FIG. The ideal straight line (line format) is indicated by reference numeral 21.

  As the premise of the magnetic simulation, the sensitivity of the two Hall sensors S1 and S2 is 2.4 mV / mT (sensitivity of a general Hall sensor), and the residual magnetic flux density Br of a rectangular parallelepiped magnet is 1200 mT (of a general neodymium sintered magnet). Value).

  From the magnetic simulation results shown in FIGS. 11 to 13 and FIG. 14, in the position detection device of the present invention, the difference value between the output voltage Va of the hall sensor S1 and the output voltage Vb of the hall sensor S2 with respect to the movement of the rectangular parallelepiped magnet is obtained. It can be seen that the value divided by the sum of the output voltages has high linearity and matches well with the ideal straight line (linear form).

  Here, the ideal straight line 21 shown in FIG. 14A represents the difference value (Va−Vb) between the output voltages of the two Hall sensors S1 and S2 when the moving distance of the rectangular parallelepiped magnet is +1 mm. The value divided by Va + Vb) and the value obtained by dividing the difference value (Va−Vb) of the output voltages of the two Hall sensors S1 and S2 when the moving distance of the rectangular magnet is −1 mm by the sum of the output voltages (Va + Vb) It is a straight line connecting

  From FIG. 14B, the difference value (Va−Vb) between the output voltage Va of the first hall sensor S1 and the output voltage Vb of the second hall sensor S2 is divided by the sum of the output voltages (Va + Vb). It can be seen that the value is slightly off the ideal line.

  Generally, since position detection is performed using a value on this ideal straight line, a difference value (Va−Vb) between the output voltage Va of the first hall sensor S1 and the output voltage Vb of the second hall sensor S2. ) Divided by the output voltage sum (Va + Vb) is large, the position detection error increases.

  FIG. 15 shows a value obtained by dividing the difference between the output voltages of the two Hall sensors S1 and S2 when the moving distance of the cuboid magnet is +1 mm, and two Hall sensors S1 and S2 when the moving distance of the cuboid magnet is −1 mm. FIG. 15 is a diagram showing an error in position detection converted from a deviation between the ideal straight line 21 and the magnetic simulation result shown in FIG. 14, with a straight line connecting values obtained by dividing the output voltage difference value by the sum as an ideal straight line 21.

  From the results shown in FIG. 15, it can be seen that the position detection error is 5 μm or less at the maximum, and the resolution achieves highly accurate position detection of 0.25% with respect to the total stroke of 2 mm.

  Naturally, the straight line obtained by the least square method from the magnetic simulation result shown in FIG. If the straight line obtained by the least square method is the ideal straight line 21, the position detection error is further reduced and the resolution is increased.

  Thus, by using the position detection device of the present invention, a significantly thin position detection device can be realized as compared with the conventional position detection device using the following comparison conditions.

<Comparison conditions>
FIG. 6 shows the configuration of a conventional position detection device. The position detection device of FIG. 6 is attached to a fixed object such as a device main body of a magnet 601 (magnet width W, magnet length L, magnet height H) attached to a moving object. The relative position with respect to the hall sensors S1 and S2 is detected. Here, the distance between the line segment connecting the first hall sensor S1 and the second hall sensor S2 is indicated by reference sign SL. The distance between the center of the magnetic sensitive surfaces of the hall sensors S1 and S2 and the magnet lower surface is indicated by reference numeral SMD. The direction of movement of the center of the magnet is indicated by reference numeral 603.

  The magnet 601 is a rectangular parallelepiped having a width W [mm], a height H [mm], and a length L [mm], and is unipolarly magnetized in the Z-axis direction. In FIG. 6, the X axis and the Y axis are directions parallel to the magnetic wall surface, and the Z axis is a direction perpendicular to the magnetic wall surface. Here, the Z-axis is a direction perpendicular to the substrate surface from the magnet toward the substrate surface. The domain wall is located at the midpoint of the height H of the magnet 601. The X axis is a direction parallel to the moving direction 603 of the magnet 601, and the Y axis is a direction perpendicular to the moving direction 603 of the magnet 601. In the following Embodiment 1 and Embodiment 2, the magnets are all neodymium sintered magnets, and the residual magnetic flux density is 1200 mT (value of a general neodymium sintered magnet).

  Under the comparison conditions described below, the first hall sensor S1 and the second hall sensor S2 are mounted on the substrate 604 with a specified distance SL therebetween, and the magnet 601 is opposed to the hall sensors S1 and S2. Be placed. At this time, the magnet 601 is arranged so that a straight line connecting the first and second Hall sensors is included in a symmetry plane that bisects the width W of the magnet 601.

  The signals from the hall sensors S1 and S2 are transmitted to the processing circuit 607 via the amplifier 605 and the A / D converter 606, and the moving part having the magnet 601 is moved according to the signal transmitted from the processing circuit 607. The drive circuit 608 connected to the processing circuit 607 is driven in the direction of the arrow 603 in FIG.

  In the configuration of the comparison condition that is the configuration of the conventional position detecting device, as shown in FIG. 6, the first hall sensor S1 and the second hall sensor S2 are separated from each other on the substrate by a predetermined distance SL. The magnet is mounted and arranged so as to face the hall sensors S1 and S2. At this time, the magnet is arranged so that the plane perpendicular to the substrate including the straight line connecting the first and second Hall sensors and the magnetic wall surface of the magnet intersect perpendicularly, and the relative motion direction of the magnet with respect to the Hall sensor is the magnetic wall surface. Parallel to That is, in the comparison condition, unlike the configuration of the first embodiment, the magnetic wall surface of the magnet 601 (the surface including the magnetic wall 602 of the magnet 601) does not include a straight line connecting the first and second Hall sensors.

  Also in the comparison condition, as in the implementation condition of the first embodiment, the position of a range of 2 mm (± 1 mm) is detected with a resolution of 5 μm in a wide temperature range.

  As a comparison condition, conventionally, a hole attached to a fixed object such as an apparatus main body of a magnet (magnet width W, magnet length L, magnet height H) attached to a moving object. The structure used for the position detection apparatus which detects the relative position with respect to sensors S1 and S2 is shown. An outline of the comparison conditions is shown in FIG. Here, the distance between the line segments connecting the first hall sensor S1 and the second hall sensor S2 is indicated by reference sign SL. The distance between the center of the magnetic sensitive surface of the hall sensors S1 and S2 and the magnet lower surface is indicated by reference numeral SMD.

  Unlike Embodiment 1, the magnetization direction is a direction perpendicular to the substrate (Z-axis direction), the magnetic wall surface is parallel to the lower surface of the magnet (XY plane) and the substrate, and the Hall sensor is not on the magnetic wall surface. . The direction of the magnetic flux detectable by the first and second Hall sensors S1 and S2 is a direction parallel to the magnetizing direction of the magnet (Z-axis direction). The moving direction of the magnet is a direction parallel to the magnetic wall surface (X-axis direction).

  Hereinafter, a design example of the optimum value of the parameter of each component in FIG. 6 will be described.

  The length L of the cuboid magnet is 2.6 mm, the width W of the cuboid magnet is 1.4 mm, and the height of the cuboid magnet is H = 0.8 mm.

  Further, the distance SMD = 1.8 mm from the plane (the bottom surface of the magnet) facing the Hall sensors S1 and S2 of the rectangular parallelepiped magnet to the center of the magnetic sensitive surface of the Hall sensors S1 and S2, the magnetic sensitive surface of the first Hall sensor S1. The distance SL between the center and the center of the magnetic sensitive surface of the second Hall sensor S2 is 1.5 mm. From this, it can be seen that the distance (H + SMD) from the center of the magnetosensitive surface of the Hall sensors S1 and S2 to the upper surface of the magnet is 2.6 mm under the comparison conditions.

From these results, the H + SMD of the position detection device using the configuration of the implementation conditions of the first embodiment can be made shorter by 0.5 mm than the H + SMD of the position detection device using the conventional configuration (comparison conditions). Thus, it can be seen that the position detection device can be thinned according to the first embodiment. By using this position detection device, it can be seen that according to the present invention, the position detection device can be remarkably thinned in consideration of the size of the optical system lens unit mounted on a mobile camera such as a mobile phone. . Further, the position detection device described above can also be used for an imaging device.
<Embodiment 2>
The configuration of the second embodiment is the same as that of the first embodiment shown in FIG.

  In both the position detection device of the second embodiment and the conventional position detection device (position detection device using comparison conditions), the resolution ratio, the magnet lower surface, and the hole when the configuration conditions of the position detection device are changed in the same way. The relationship of the distance SMD with the center of the magnetic sensitive surface of sensor S1, S2 was calculated | required by the magnetic simulation, and the result was shown to FIGS. Here, the configuration of the comparison condition is the same as the configuration shown in FIG.

  The structural conditions of the device referred to here are the width W, height H, length L of the magnet and the distance SL of the line connecting the two Hall sensors S1, S2. The resolution ratio referred to here is a value obtained by dividing the difference between the actual moving distance of the magnet and the moving distance of the magnet detected by the position detection device as an error, and dividing the maximum value of the error by the movable range of the magnet. The unit is [μm / mm]. 7 to 10, the vertical axis represents the resolution ratio, and the horizontal axis represents the distance (SMD) between the lower surface of the magnet and the center of the magnetic sensitive surface of the Hall sensors S1 and S2.

  Differences in the configuration conditions of the position detection device described above are shown in the legends of FIGS. Specifically, in FIGS. 7 to 10, the implementation condition 123-1.5 is the implementation condition WHL-SL, in which the magnet width W = 1 mm, height H = 2 mm, length L = 3 mm, This is a position detection device using the configuration of the present invention (Embodiment 1) in which the distance SL between the hall sensors S1 and S2 is 1.5 mm. 7 to 10, the comparison condition 123-1.5 is the comparison condition WHL-SL, in which the magnet width W = 1 mm, height H = 2 mm, length L = 3 mm, Hall sensor S1. , S2 is a position detection device using a conventional (comparison condition) configuration with a distance SL = 1.5 mm.

  In all implementation conditions and comparison conditions, the magnet dimensions are such that the magnet width W is 1 mm, 2 mm, the height H is 1 mm, 2 mm, the length L is 2, 3 mm, and the distance SL between the Hall sensors S1, S2 is These conditions were comprehensively set to 0.8 mm and 1.5 mm, and a magnetic simulation was performed. The stroke of the magnet was 2 mm in all implementation conditions and comparison conditions.

  These differences are shown separately in FIGS. 7 to 10 by the magnet length L and the distance SL between the hall sensors S1 and S2.

  In FIG. 7, the distance SL between the hall sensors S1 and S2 is 0.8 mm, the magnet length L is 2 mm, and the magnet width W and height H are (W [mm] and H [mm]) = (1 mm), respectively. (1 mm), (1 mm, 2 mm), (2 mm, 1 mm), and (2 mm, 2 mm).

  FIG. 8 shows that the distance SL between the hall sensors S1 and S2 is 0.8 mm, the magnet length L is 3 mm, and the magnet width W and height H are the same as those shown in FIG. The magnetic simulation result is shown.

  9 shows a magnetic field under the condition that the distance SL between the hall sensors S1 and S2 is 1.5 mm, the magnet length L is 2 mm, and the magnet width W and height H are the same as those shown in FIG. Simulation results are shown.

  FIG. 10 shows a magnetic field under the condition that the distance SL between the hall sensors S1 and S2 is 1.5 mm, the magnet length L is 3 mm, and the magnet width W and height H are the same as those shown in FIG. Simulation results are shown.

  From the magnetic simulation results shown in FIGS. 7 to 10, the position detection device using the configuration of the second embodiment has a lower magnet surface than the position detection device using the conventional configuration even though the size of the magnet is the same. In the region where the distance (SMD) between the sensor and the center of the magnetosensitive surface of the Hall sensors S1 and S2 is short, an effect that a resolution equal to or higher than that of the position detecting device under the comparison condition using the conventional configuration can be obtained. I understand.

  By using this position detection device, it can be seen that according to the present invention, the position detection device can be remarkably thinned in consideration of the size of the optical system lens unit mounted on a mobile camera such as a mobile phone. . Further, the position detection device described above can also be used for an imaging device.

It is the figure which showed the example of the position detection apparatus. It is a layout view of the magnet and the magnetic sensor of the present invention. It is a perspective view of the structure used for the position detection apparatus of this invention. It is a side view from the Y direction of the structure used for the position detection apparatus of this invention. It is explanatory drawing which shows an example of the signal processing method at the time of detecting a position using a Hall sensor. It is a perspective view of the structure of the comparison conditions used for the conventional position detection apparatus. The working conditions with the distance SL between the hall sensors S1 and S2 of 0.8 mm and the magnet length L = 2 mm, the resolution ratio under the comparison conditions, the lower surface of the magnet, and the center of the magnetosensitive surface of the hall sensors S1 and S2. It is the figure which showed the relationship of distance (SMD). The working conditions with the distance SL between the hall sensors S1 and S2 of 0.8 mm and the magnet length L of 3 mm, the resolution ratio under the comparison conditions, the bottom surface of the magnet, and the center of the magnetosensitive surface of the hall sensors S1 and S2. It is the figure which showed the relationship of distance (SMD). The distance between the hall sensors S1 and S2 is SL = 1.5 mm, the length of the magnet is L = 2 mm, the resolution ratio under the comparison conditions, the lower surface of the magnet and the center of the magnetosensitive surface of the hall sensors S1 and S2. It is the figure which showed the relationship of distance (SMD). Implementation conditions under the distance SL = 1.5 mm between the hall sensors S1, S2 and the magnet length L = 3 mm, the resolution ratio under the comparison conditions, the bottom surface of the magnet, and the center of the magnetosensitive surface of the hall sensors S1, S2. It is the figure which showed the relationship of distance (SMD). It is explanatory drawing which shows the magnetic flux density change in the position of 1st Hall sensor S1 with respect to the moving distance of a magnet. It is explanatory drawing which shows the magnetic flux density change in the position of 2nd Hall sensor S2 with respect to the moving distance of a magnet. It is explanatory drawing which shows the change of the difference magnetic flux density which pulled the magnetic flux density in the position of 1st Hall sensor S1 from the magnetic flux density in the position of 2nd Hall sensor S2 with respect to the moving distance of a magnet. (A) is a magnetic simulation of a value obtained by dividing the difference value of the output voltage between the Hall sensors with respect to the moving distance of the rectangular magnet by the sum of the output voltages when the position detection device of FIG. It is explanatory drawing which shows the result calculated | required from (b), and is an enlarged view. It is explanatory drawing which shows the position detection error with respect to the moving distance of a rectangular parallelepiped magnet converted from the shift | offset | difference of an ideal straight line shown in FIG. 13, and a magnetic simulation result. It is the figure which showed the example of the mold package.

Explanation of symbols

W Magnet width L Magnet length H Magnet height S1 Hall sensor S2 Hall sensor SL Distance SMD Distance ST Movement range of magnet center 11 Magnetic flux density change 12 Magnetic flux density change 13 Difference of magnetic flux density change 21 Ideal straight line 22 region

Claims (5)

  A position detection device comprising a magnet attached to an object for detecting a position and two magnetic flux detection means for detecting a change in magnetic flux due to relative movement of the magnet, wherein two magnetic fluxes are provided on a magnetic wall surface of the magnet. A position detection apparatus comprising a straight line connecting detection means, wherein a relative movement direction of the magnet with respect to the magnetic flux detection means is parallel to the magnetic wall surface.   The position detecting device according to claim 1, wherein the magnetic flux detecting means is capable of detecting a magnetic flux component parallel to the magnetizing direction of the magnet.   The position detection device according to claim 1, wherein the magnetic flux detection means is a Hall sensor.   An optical system using the position detection device according to claim 1.   An image pickup apparatus using the optical system according to claim 4.

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