JP2013041200A - Position detector using magnetoresistive element and lens barrel using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact position detector capable of being easily assembled and adjusted, and a lens barrel capable of obtaining superior output characteristics even when incorporating this position detector and a linear motor.SOLUTION: A position detector includes: a magnetic recording medium 123; a magnetoresistive element 3; an adjustment member 11 for adjusting space between the magnetic recording medium 123 and the magnetoresistive element 3; a shield member 13 for shielding magnetic fields detected by the magnetoresistive element 3 except magnetic fields by the magnetic recording medium 123; a wiring member 15 which is electrically connected to the magnetoresistive element 3; and a buffer member 5 for pressing the magnetoresistive element 3 toward a stator 7. A lens barrel in which a lens is driven by a linear motor is provided with the position detector at a position other than a substantially symmetric center position of the linear motor arranged bilaterally symmetrically in an optical axis direction.

Description

  The present invention relates to a position detection device that detects the position of an object, and in particular, a position detection device using a magnetoresistive (Magneto Resistive, MR) element, and a lens mirror such as a still camera or a video camera using the position detection device. Related to the tube.

  A magnetoresistive element is an element that utilizes the phenomenon that the magnetoresistance value changes when a magnetic field is applied to a semiconductor thin film such as indium / antimony (InSb). A position detection device using this type of magnetoresistive element is widely used for position detection of a magnetic recording medium in combination with a magnetic recording medium such as a ferrite or a plastic magnet.

  This magnetoresistive element can detect a change in the magnetic field due to the movement of the magnetic recording medium, and obtain a sine curve-like reproduction output. By processing this output waveform, the relative or absolute position of the magnetic recording medium is obtained with high accuracy.

  When detecting the movement of the magnetic recording medium, the magnetoresistive element needs to adjust the distance from the magnetic recording medium appropriately. This is called a reference gap amount and is determined by the specifications of the magnetic recording medium. If the interval is wider than the reference gap amount, the output of the position detection device is suddenly reduced. Conversely, if the interval is narrowed, the output is distorted and a sine curve reproduction output cannot be obtained. Magnetoresistive elements that are widely used in consumer and industrial equipment are provided with adjusting means that can be roughly divided into two types in order to satisfy this requirement.

  The contact-type magnetoresistive element is insert-molded in a non-magnetic resin or the like, and a resin having a thickness corresponding to the reference gap amount is previously placed on the sensing surface as a spacer. Therefore, the reference gap amount can always be maintained by bringing a contact-type magnetoresistive element into close contact with the magnetic recording medium and sliding the surface of the magnetic recording medium.

  As this type of position detection device, for example, disclosed in Patent Document 1, a structure in which a magnetoresistive element held by a leaf spring from a fixed member is in close contact with a magnetic recording medium attached to a rotating member. It has become. Such a position detection device has an advantage that adjustment of the reference gap amount is unnecessary.

  On the other hand, the non-contact type magnetoresistive element has an advantage that noise and wear caused by sliding with the magnetic recording medium can be eliminated because the position can be detected without contacting the magnetic recording medium. . However, since it is necessary to adjust the reference gap amount for each individual, there is a drawback that the manufacturing cost is increased. The non-contact type magnetoresistive element is insert-molded in a non-magnetic resin or the like as in the case of the contact type magneto-resistive element, but a mechanism for mounting and adjusting the gap amount is integrally formed.

  This type of position detection device is disclosed in, for example, Patent Document 2, and has a structure that allows attachment and adjustment of the gap amount.

  By the way, in a lens barrel used for a still camera, a video camera, or the like, a lens barrel that moves with a linear motor during zoom operation or focus operation is known. When using this motor to move the lens, the motor itself does not have position information, so a separate position detection means is required. In addition, since the structure is less likely to generate noise during operation, a method using the above-described position detection device using the non-contact type magnetoresistive element for detecting the lens position is known because of the characteristics that are preferable particularly during moving image shooting.

  FIG. 7 shows the structure of a lens barrel 200 using such a linear motor. A focus lens 201 is held by a lens frame 203 inside the lens barrel 200. The lens frame 203 is supported at both ends so as to be slidable in the optical axis direction along the main shaft 209 and the sub shaft 211 fixed to the lens barrel 299 and the guide shaft receiver 206. The linear motor that drives the lens frame 203 in the optical axis direction includes a driving magnet 213 magnetized perpendicularly to the driving direction as a stator, a U-shaped main yoke 215, and a plate-shaped side yoke 217. 299. On the other hand, the coil 219 as a mover is fixed to the lens frame 203 so as to have a predetermined gap with the driving magnet 213, and a current is passed through the coil 219 so as to be orthogonal to the magnetic flux generated by the driving magnet 213. The lens frame 203 is driven in the optical axis direction.

  Next, the position detection device will be described. In FIG. 7, a magnetic scale 223 made of a magnetic recording medium such as ferrite is provided on the lens frame 203, and the surface thereof has S poles at a pitch of about 150 to 400 μm along the optical axis direction that is the driving direction of the lens frame 203. N poles are alternately magnetized. The holder 205 is held by the lens barrel 299 so that the sensitive surface made of the magnetoresistive element faces the magnetic scale 223 with a predetermined interval. The holder 205 can rotate around the pin 233 when the pin 233 is inserted into the rotation hole 235. Therefore, a method is generally used in which the holder 205 is rotated to adjust the distance between the magnetic scale 223 and the sensing surface and then fixed with an inclination adjusting screw 225 passed through the long hole 227.

  Further, as a position detection device using a non-contact type magnetoresistive element, for example, in Patent Document 3, a holder that holds a magnetoresistive element facing a magnetic recording medium is provided with a protrusion having a curved surface with a substantially constant curvature. At the same time, when the holder is attached to the member to be attached by the positioning means, the holder rotates about the central axis of the curved surface of the protruding portion, thereby adjusting the distance between the magnetic scale and the sensing surface.

  Further, as a position detecting device using a non-contact type magnetoresistive element, for example, in Patent Document 4, a holder for holding a magnetoresistive element facing a magnetic recording medium is provided with a mounting hole, and a member to be attached is attached to the holder. The frame member and the fastening hole are provided, the elastic member is provided between the holder and the member to be attached, and the screw member having the screw-free guide part, the self-tap screw part, and the head part is provided for the attachment hole and fastening. The distance between the magnetic scale and the sensing surface is adjusted by being inserted through the hole and moving in parallel with the screw member.

  Further, as a position detection device using a non-contact type magnetoresistive element and a lens barrel using the same, for example, in Patent Document 5, the position detection device using a magnetoresistive element affects the influence of leakage magnetic flux from a linear motor. Since the S / N ratio of the position detection device deteriorates or does not function depending on the degree, the linear motor is arranged symmetrically in the drive direction, and the position detection device has a substantially symmetrical center in the drive direction of the linear motor. The structure which solves this by providing in a position is shown.

JP 2002-250638 A JP-A-1-203922 JP 2000-2559 A JP 2003-241055 A Japanese Patent No. 3750251

  However, in the position detection device configured as described above, the work of adjusting the distance between the magnetic recording magnetic scale 223 and the sensitive surface and the work of fixing the holder 205 must be performed separately, and the assembly work is complicated. This has been a cause of increasing the manufacturing cost of the device.

  For adjusting the reference gap amount, for example, when the magnetization pitch of the magnetic scale 223 is 200 μm, the reference gap amount needs to be set within a tolerance of about 100 ± 20 μm. The operation of rotating the holder 205 around the pin 233 and positioning the holder 205 at a position within such a small tolerance is extremely difficult and has been a factor that further increases the manufacturing cost.

  In addition, a gap of several tens of μm or more exists between the pin 233 and the rotation hole 235 into which the pin 233 is inserted due to the processing accuracy. For this reason, even if the holder 205 is intended to rotate around the pin 233, the holder 205 often translates by the amount of the clearance from the rotation hole 235. For this reason, it is very difficult to make a fine adjustment of 10 μm.

  Further, the holder 205 changes the interval with the magnetic scale 223 while rotating around a pin 233 provided at one end. Therefore, the magnetic scale 223 and the sensitive surface are not parallel except for one point. Therefore, the distance between the magnetic scale 223 and the sensitive surface of the holder 205 in the optical axis direction may not be uniform. In general, a plurality of magnetoresistive elements are arranged in a pattern on the sensitive surface in the optical axis direction. If the distance between the magnetic scale 223 and the sensing surface is different in the pattern direction, the output characteristics are different for each pattern, resulting in a disadvantage that the output characteristics of the position detection device are deteriorated.

  Moreover, in the position detection apparatus having a configuration as shown in Patent Document 3, the work of adjusting the distance between the magnetic scale and the sensing surface and the work of fixing the holder can be performed simultaneously. However, as shown in FIG. 8 and FIG. 9 of Patent Document 3, if the distance between the magnetic scale and the sensitive surface is extremely adjusted, the sensitive surface is tilted with respect to the magnetic scale and becomes not parallel. The interval will change. As a result, there is a drawback that the output characteristics of the position detection device deteriorate.

  Further, in the position detection device having a configuration as shown in Patent Document 4, although the work of adjusting the interval between the magnetic scale and the sensing surface and the work of fixing the holder can be performed simultaneously, the parallelism of the magnetic scale and the sensing surface is the same as that of the holder. This is only due to the accuracy of the frame portion formed on the member to be attached, and does not have the technique of correcting the fall as in Patent Document 3. Therefore, when molding accuracy cannot be ensured, the distance between the magnetic scale and the sensitive surface is not uniform, and as a result, there is a disadvantage that the output characteristics of the position detection device deteriorate.

  Further, in the position detection device configured as shown in Patent Document 4, since the frame portion to which the holder is attached projects in the radial direction of the lens barrel, the outer diameter of the lens barrel is increased. .

  Further, in the position detection device configured as shown in Patent Document 5 and a lens barrel using the position detection device, restrictions are imposed on the arrangement of the linear motor and the position detection device, so that the degree of freedom in designing the lens barrel is lowered. This increases the size of the lens barrel and increases the cost. On the other hand, if the position detection device is arranged ignoring the influence of the leakage magnetic flux from the linear motor, normal position detection cannot be performed.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a small position detection device that can be easily assembled and adjusted, and that can provide good output characteristics even when incorporated with a linear motor, and a lens barrel using the position detection device.

  Therefore, the present invention achieves the above object by the following means. In order to facilitate understanding, description will be made with reference numerals corresponding to the drawings showing an embodiment of the present invention, but the present invention is not limited to this.

  The invention described in claim 1 is provided in the mover, the magnetic recording medium having N and S poles magnetized at a predetermined pitch along the drive direction of the mover, and the magnetic recording medium provided in the stator. A magnetoresistive element facing the medium, an adjustment member inserted between the stator and the magnetoresistive element, and adjusting a distance between the magnetic recording medium and the magnetoresistive element by changing a thickness; A hole is inserted between the stator and the magnetoresistive element to expose the sensitive surface of the magnetoresistive element, and shields the magnetic field detected by the magnetoresistive element other than the magnetic field generated by the magnetic recording medium. A shielding member, a wiring member electrically connected to the magnetoresistive element, a fixing member provided on the stator, and fixing the magnetoresistive element to the stator, provided on the fixing member, Magnetoresistive element to the stator Only by the position detecting device characterized by having a buffer member for pressing.

  According to a second aspect of the present invention, the magnetoresistive element has a shape in which a sensitive surface protrudes, and is inserted into a hole having substantially the same shape as the sensitive surface provided in the shielding member, and the sensitive surface is the shielding member. The position detection device according to claim 1, wherein the position detection device is disposed on the same surface as or protruding from the surface of the surface.

  According to a third aspect of the present invention, there is provided a fixed cylinder that is the stator, a guide shaft that is supported inside the fixed cylinder, a moving lens group that moves in the optical axis direction along the guide axis, and the guide A lens frame that is slidably held in the optical axis direction by the shaft, holds the moving lens group, and is a mover; driving means for driving the lens frame in the optical axis direction; and And a position detection device that detects a position in the optical axis direction. When the position detection device according to claim 1 or 2 is used as the position detection device, the driving means is arranged symmetrically in the optical axis direction. The lens barrel is characterized in that the position detecting device is provided at a position other than a substantially symmetrical center position in the driving direction of the driving means.

  The invention shown in claim 4 is the lens barrel according to claim 3, wherein the driving means is a linear motor, the stator is provided with a magnet and a yoke, and the movable element is provided with a coil. .

  SUMMARY OF THE INVENTION An object of the present invention is to provide a small position detection device that can be easily assembled and adjusted, and a lens barrel that can obtain good output characteristics even when this and a linear motor are incorporated.

It is AA sectional drawing in FIG. 6 of the lens-barrel 100 in the Example of this invention. It is an expanded view which shows the sensor unit 1 in the Example of this invention. It is a perspective view which shows MR sensor 3 in the example of the present invention. It is a perspective view which shows the fixed cylinder 99 in the Example of this invention. It is a perspective view which shows the lens frame 103 in the Example of this invention. 1 is a development view of a lens barrel 100 in an embodiment of the present invention. FIG. 6 is a development view of a conventional lens barrel 200.

  Embodiments of the sensor unit 1 of the present invention and a lens barrel 100 using the same will be described with reference to FIGS. 1 is a cross-sectional view of the lens barrel 100 taken along line AA in FIG. 6, FIG. 2 is a development view showing the sensor unit 1, FIG. 3 is a perspective view showing the MR sensor 3, and FIG. FIG. 5 is a perspective view showing the lens frame 103, and FIG. 6 is a development view of the lens barrel 100.

  First, the structure of the sensor unit 1 which is the position detection device of the present invention will be described. In the sensor unit 1 of the present invention, as shown in FIG. 1, the MR sensor 3 is provided in a fixed cylinder 99 which is a stator, and the displacement of a magnetic scale 123 provided in a lens frame 103 which is a mover is detected. It has a structure to detect. The fixed cylinder 99 is provided with a gap amount adjusting mechanism for adjusting the distance between the MR sensor 3 and the magnetic scale 123. In addition, a shield plate 13 that shields the magnetic field is provided in the vicinity of the MR sensor 3 so that a magnetic field generated by another device provided in the fixed cylinder 99 does not adversely affect the MR sensor 3.

  Here, the configuration of the sensor unit 1 will be described with reference to FIG. The sensor unit 1 serving as a position detection device includes a shield plate 13, a spacer 11, and an MR sensor in order from the magnetic scale 123 provided on the lens frame 103 and the magnetic scale 123 provided on the fixed cylinder 99. 3, the FPC 15, the cushioning material 5, the fixing plate 7, and the fixing screw 9 that fastens the fixing plate 7 to the fixing cylinder 99. Among these, the shield plate 13 is directly fixed to the fixed cylinder 99, the MR sensor 3 is attached to the FPC 15, and the cushioning material 5 is attached to the fixed plate 7.

  As shown in FIG. 3, the MR sensor 3, which is a magnetoresistive element, has a sensitive surface 3a exposed on the surface, and a connection terminal 3b for inputting and outputting signals is integrally fixed to an insulating resin by insert molding or the like. ing. The MR sensor 3 is formed with a thin film pattern so that a change in the magnetic field in a direction parallel to the sensitive surface 3a can be detected, and the sensitive surface 3a is placed facing the magnetic scale 123 to detect its position. Use. The MR sensor 3 is mounted on a flexible printed cable (FPC) 15 which is a wiring member to be described later by a known electronic component mounting means, and is electronically and mechanically coupled. The MR sensor 3 has a shape that only the sensitive surface 3a protrudes through a shield plate 13 described later. The change in the magnetic field due to the displacement of the magnetic scale 123 detected by the MR sensor 3 is converted into an electric signal and transmitted to the control board (not shown) by the FPC 15.

  The shield plate 13 serving as a shielding member is configured to shield the magnetic field so that the influence of the magnetic field by another device does not reach the MR sensor 3. More specifically, as described above, the sensing surface 3a of the MR sensor 3 has a protruding shape, and an opening 13a having substantially the same shape as the sensing surface 3a is provided at the center of the shield plate 13, and magnetically Magnetic fields other than the scale 123 are prevented from wrapping around the sensitive surface 3a. With this shape, the sensing surface 3a and the magnetic scale 123 are not blocked. A projection 13 b is formed at the lower end of the shield plate 13. The shield plate 13 is inserted into the opening 99a of the fixed cylinder 99 shown in FIG. 4 in parallel with the optical axis, and abuts against the two protrusions 99b below the opening. At that time, the projection 13b of the shield plate 13 is fitted into the recess 99c below the opening 99a. As a result, the shield plate 13 is held between the pillar portion of the opening 99a and the bridge portion 99e, and becomes a seating surface on which a spacer 11 described later comes into contact. The shield plate 13 is made of a metal with high magnetic permeability such as iron or nickel having a thickness of about 1 mm, and is formed by press working or die casting.

  The spacer 11 serving as an adjustment member is inserted between the MR sensor 3 and the shield plate 13, and the distance between the sensitive surface 3 a of the MR sensor 3 and the magnetic scale 123 can be adjusted by changing the thickness thereof. it can. Similar to the shield plate 13, the spacer 11 is provided with an opening 11 a having substantially the same shape as the sensitive surface 3 a of the MR sensor 3, so that the sensitive surface 3 a of the MR sensor 3 can be inserted. In addition, spacers 11 having different thicknesses (for example, three types of 1/10 mm, 5/100 mm, and 3/100 mm) are prepared and used in a gap amount adjusting step described later. The spacer 11 is made of a metal such as stainless steel, aluminum, or brass, and is generally molded by pressing.

  A flexible printed cable (FPC) 15 serving as a wiring member is electrically connected to the MR sensor 3 and transmits a signal output from the MR sensor 3 to a control board (not shown). The FPC 15 includes a connecting portion 15a at one end thereof, and is inserted and fixed to a connector provided on a control board (not shown). The FPC 15 includes a connector 15d at the other end, and can be connected to another FPC (here, a flexible printed cable for driving 120 described later). Since the FPC 15 has a flexible film shape and is partially coated with an adhesive, the FPC 15 is attached and fixed to the groove 99h provided on the side surface of the fixed cylinder 99 shown in FIG. Further, the FPC 15 is bent at the bending portion 15b and is folded in a direction parallel to the optical axis. Here, the FPC 15 can swing from the bent portion 15b with the MR sensor 3 mounted on the tip portion 15c. Thus, even after the FPC 15 is attached to the fixed cylinder, the tip 15c on which the MR sensor 3 is mounted can be once largely shifted from the fixed cylinder 99, so that the workability of the gap amount adjustment process by changing the spacer 11 is good. became.

  The buffer material 5 serving as a buffer member is provided on the opposite surface of the front end portion 15c of the FPC 15 from the surface on which the MR sensor 3 is mounted, and the MR sensor 3 is moved toward the shield plate 13 together with the fixing plate 7 to be described later. To do. The shock-absorbing material 5 is a quadrangle whose section is substantially the same as that of the MR sensor 3, and the thickness is slightly thicker than the gap into which the shock-absorbing material 5 is to be inserted, and the shock-absorbing material 5 is sandwiched while being slightly crushed with its elasticity. The buffer material 5 is a closed cell foam such as urethane foam. The buffer material 5 is attached to the fixing plate 7 with an adhesive and is provided so that the position where the FPC 15 is pressed is not shifted.

  The fixing plate 7, which is a fixing member, has a shape in which a thin plate is bent in an L shape, and a tip portion 7 f thereof is inserted into a locking groove 99 f provided in the fixing cylinder 99. Further, the fixing plate 9 is fixed to the fixing cylinder 99 by inserting the fixing screw 9 into the two holes 7g provided in the fixing plate 7 and fastening to the two holes 99g provided in the fixing cylinder 99, respectively. Is done. The fixing plate 7 is generally made of a metal such as stainless steel or aluminum, and is generally molded by pressing.

  The magnetic scale 123, which is a magnetic recording medium, is a polyethylene terephthalate tape whose surface is coated with a magnetic material such as ferrite, and is attached to a base material such as polycarbonate molded into a rectangular parallelepiped. The magnetic scale 123 is alternately magnetized with S and N poles at a pitch of 100 to 400 μm along the driving direction. The magnetic scale 123 is fitted into the holding frame 103a provided on the lens frame 103 with the magnetized surface facing outward, and an adhesive is applied to the grooves 103b provided on both side surfaces of the holding frame 103a. Fixed. The adhesive used at this time is preferably a workable material such as an ultraviolet curable resin.

  In the sensor unit 1 configured in this way, the shield plate 13 shields the leakage magnetic flux from other components in the lens barrel, in particular, the linear motor, and the MR sensor 3 can accurately detect the position without being affected by this. It can be carried out. Accordingly, the sensor unit 1 can be freely arranged in the lens barrel, and the lens barrel can be reduced in size by optimizing the arrangement.

  Further, in the sensor unit 1 configured in this way, the movement of the MR sensor 3 accompanying the gap amount adjustment process is only a linear movement in the adjustment direction. Therefore, the opening 13a provided in the shield plate 13 to expose the sensitive surface 3a of the MR sensor 3 has substantially the same shape as the sensitive surface 3a. If the opening 13a is too large with respect to the sensing surface 3a, a sufficient shielding effect cannot be obtained. However, the sensor unit 1 according to the present invention can have a minimum opening area. Therefore, it can be set as the structure which draws out the shielding effect of the shield board 13 to the maximum.

  In addition, the use of the spacer 11 simplifies the gap amount adjustment process, and at the same time, produces an effect that the backlash and the fall of the MR sensor 3 associated with the gap amount adjustment process do not occur. In the conventional position detection device using the magnetoresistive element, since the stepless adjustment is performed by the screw, the sensor unit 1 is thin in the radial direction and has an effect of suppressing the outer diameter of the lens barrel.

  Next, the structure of the lens barrel 100 using the sensor unit 1 of the present invention will be described with reference to FIG.

  Inside the lens barrel 100, a focus lens 101 which is a moving lens group is held by a lens frame 103 which is a lens holding means. The lens frame 103 is supported at both ends so as to be slidable in the optical axis direction along the main shaft 109 and the sub shaft 111 fixed to the fixed cylinder 99, the main bearing 105, and the sub bearing 107. The lens barrel 100 is a part of a lens device that is attached to or built in an imaging device such as a single-lens reflex camera. A lens group, a diaphragm unit, a control board, and the like (not shown) are arranged in the optical axis direction. .

  The linear motor as a driving means for driving the lens frame 103 in the optical axis direction includes a driving magnet 113 magnetized perpendicularly to the driving direction as a stator, a U-shaped main yoke 115 and a plate-shaped side yoke 117. Are provided in the fixed cylinder 99. On the other hand, a coil 119 as a mover is fixed to the lens frame 103 so as to have a predetermined gap with the driving magnet 113, and is orthogonal to the magnetic flux generated by the driving magnet 113 using the driving flexible printed cable 120. Similarly, the lens frame 103 is driven in the optical axis direction by passing a current through the coil 119. The flexible printed cable 120 for driving can be connected to a connector 15d provided on the FPC 15 to receive power supply for driving the linear motor via the FPC 15.

  Then, the actual gap amount adjustment process of the sensor unit 1 of this invention is demonstrated. As described above, the MR sensor 3 has a characteristic that when the interval is wider than the reference gap amount, the output is rapidly reduced, and conversely, when the interval is narrowed, the output is distorted. The gap amount adjustment step uses this characteristic, and adjusts the distance between the sensitive surface 3a of the MR sensor 3 and the magnetic scale 123 by the method as described below.

  First, the shield plate 13 is inserted into the fixed cylinder 99, then the spacer 11 is inserted, the MR sensor 3 previously mounted on the FPC 15 is attached, and the fixed plate 7 on which the buffer material 5 is attached is attached. At this time, the number of spacers 11 to be inserted is increased or decreased depending on the convenience of design. In this embodiment, a spacer having a thickness of 1/10 mm and a spacer having a thickness of 5/100 mm are inserted one by one.

  Subsequently, the connecting portion 15a of the FPC 15 is connected to an adjustment tool (not shown). As described above, the FPC 15 is connected to the coil 119 via the MR sensor 3 and the flexible printed cable 120 for driving. In other words, the linear motor drive in the lens barrel 100 and the output of the MR sensor 3 can be confirmed simply by connecting one flexible printed cable to the connector of the adjustment tool.

  Subsequently, the adjustment tool is operated, and a current is supplied to the coil 119 via the FPC 15 and the flexible printed cable 120 for driving, and the lens frame 103 is continuously reciprocated in the optical axis direction. At this time, the output of the MR sensor 3 is measured via the FPC 15 with an oscilloscope or the like mounted on the adjustment tool, and the sine curve-shaped reproduction output waveform and its peak voltage are monitored. Here, it is determined whether the gap amount is appropriate by comparing with the reference voltage according to the specification of the MR sensor 3.

  At this time, for example, when the peak voltage is smaller than the reference voltage, it can be determined that the distance between the sensitive surface 3a and the magnetic scale 123 is too wide. In this case, the fixing screw 9 is once loosened, the fixing plate 7 is removed, the FPC 15 is bent with the bent portion 15b as an axis, the MR sensor 3 is lifted forward, and the inserted spacer 11 is changed to a thin one. In the embodiment, since one of the initial thickness of 1/10 mm and the thickness of 5/100 mm are inserted one by one, using the previously prepared spacer 11, the thickness of 5/100 mm is obtained. Replace with one with a thickness of 3/100 mm.

  At this time, for example, when the peak voltage is larger than the reference voltage or the waveform is distorted to become a triangular wave, it can be determined that the distance between the sensitive surface 3a and the magnetic scale 123 is too narrow. In this case, the fixing screw 9 is once loosened, the fixing plate 7 is removed, the FPC 15 is bent with the bent portion 15b as an axis, the MR sensor 3 is turned up, and the inserted spacer 11 is changed to a thicker one. In the embodiment, since one of the initial thickness of 1/10 mm and the thickness of 5/100 mm are inserted one by one, using the previously prepared spacer 11, the thickness of 3/100 mm is used. Insert additional.

  When the spacer 11 is changed, the MR sensor 3 is returned to the original position, and the fixing plate 7 is attached again. Then, the adjustment tool is operated to determine again whether or not the gap amount is appropriate. Here, if an appropriate waveform is measured, the gap amount adjustment process is terminated. If an appropriate waveform is not yet obtained, the spacer 11 is changed again.

  In this way, the sensor unit 1 that performs the gap amount adjusting process and the lens barrel 100 using the sensor unit 1 can perform the disassembly / reassembly process associated with the change of the spacer 11 very easily. Since the assembly time can be reduced, the manufacturing cost can be reduced.

  That is, the present invention aims to provide a compact position detecting device that can be easily assembled and adjusted, and that can provide good output characteristics even when incorporated with a linear motor, and a lens barrel using the same. A recording medium; a magnetoresistive element; an adjustment member that adjusts an interval between the magnetic recording medium and the magnetoresistive element; and a shielding member that shields a magnetic field detected by the magnetoresistive element other than the magnetic field generated by the magnetic recording medium. And a wiring member electrically connected to the magnetoresistive element and a buffer member that presses the magnetoresistive element toward the stator.

  The position detection device according to the present invention is appropriately deformed and enlarged / reduced depending on the imaging device to which the present invention is applied and the lens barrel to which the position detection device is attached. In addition, various modifications and changes such as a change in appearance due to a change in the external dimensions of the apparatus and a coupling position between members are possible as necessary, but all are within the equivalent scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Sensor unit 3 MR sensor 5 Buffer material 7 Fixing plate 9 Fixing screw 11 Spacer 13 Shield plate 15 Flexible printed cable 99 Lens barrel 100 Lens barrel 101 Focus lens 103 Lens frame 105 Main bearing 107 Sub bearing 109 Main shaft 111 Sub shaft 113 Driving Magnet 115 Main yoke 117 Side yoke 119 Coil 120 Flexible printed cable for driving 123 Magnetic scale 200 Lens barrel 201 Focus lens 203 Lens frame 205 Holder 206 Guide shaft receiver 209 Main shaft 211 Sub shaft 213 Driving magnet 215 Main yoke 217 Side yoke 219 Coil 223 Magnetic scale 225 Tilt adjustment screw 227 Long hole 233 Pin 235 Rotating hole 299 Lens barrel

Claims (4)

A magnetic recording medium provided on the mover and having N and S poles magnetized at a predetermined pitch along the drive direction of the mover;
A magnetoresistive element provided on the stator and facing the magnetic recording medium;
An adjustment member that is inserted between the stator and the magnetoresistive element, and adjusts the distance between the magnetic recording medium and the magnetoresistive element by changing the thickness;
A hole is inserted between the stator and the magnetoresistive element to expose the sensitive surface of the magnetoresistive element, and shields the magnetic field detected by the magnetoresistive element other than the magnetic field generated by the magnetic recording medium. A shielding member that,
A wiring member electrically connected to the magnetoresistive element;
A fixing member provided on the stator and fixing the magnetoresistive element to the stator;
A position detection apparatus comprising: a buffer member provided on the fixing member and pressing the magnetoresistive element toward the stator.   The magnetoresistive element has a shape in which a sensitive surface protrudes, is inserted into a hole having substantially the same shape as the sensitive surface provided in the shielding member, and the sensitive surface is flush with or protrudes from the surface of the shielding member. The position detection device according to claim 1, wherein the position detection device is arranged. A fixed cylinder that is the stator; and
A guide shaft supported inside the fixed cylinder;
A moving lens group that moves in the optical axis direction along the guide axis;
A lens frame that is slidably held in the optical axis direction by the guide shaft, holds the moving lens group, and is a mover.
Driving means for driving the lens frame in the optical axis direction;
A position detection device for detecting the position of the lens frame in the optical axis direction;
Using the position detection device according to claim 1 or 2 as the position detection device,
A lens barrel characterized in that, when the driving means is arranged symmetrically in the optical axis direction, the position detecting device is provided at a position other than the substantially symmetrical center position in the driving direction of the driving means. The drive means is a linear motor;
A magnet and a yoke are provided on the stator,
The lens barrel according to claim 3, wherein the movable element is provided with a coil.

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