JP2002214501A - Device and optical device provided with position detecting sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that the position of a movable member is not accurately detected when the magnetized surface of an encoder magnet held by the movable member is not parallel with a magnetic sensing type sensor. SOLUTION: In the device or the optical device provided with a movable member 5 (5a) movable in a prescribed direction X-X, the encoder magnet 14 positioned and held by the movable member, and the magnetic sensing type position detecting sensor 16 arranged to be opposed to the magnetized surface 14a of the magnet 14, the magnet 14 is positioned to the movable member so that the magnetized surface of the magnet 14 and the magnetic sensing surface of the position detecting sensor 16 may be nearly parallel with each other in the prescribed direction in a state where space (t) is left between the surface 14b on an opposite side to the magnetized surface of the magnet 14 and the movable member.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device having a magnetic sensing type position detecting sensor and an optical device such as a taking lens barrel used for an image pickup device such as a video camera and a digital still camera.

[0002]

2. Description of the Related Art Recently, the performance and image quality of digital video cameras, digital still cameras, and the like have been improved, and accordingly, the required performance of a photographic lens unit has been increased.

In particular, in order to increase the speed of focusing and the precision of position control of the focus lens, a linear actuator composed of a magnet and a coil has been used for driving a moving lens group such as a focus lens. I have.

[0004] Further, for position control of the moving lens group, a fine position detection system in which an MR sensor which is a magnetic sensing (or magnetic intensity sensing) sensor and an encoder magnet are combined is used.

Here, since the output characteristics of the MR sensor greatly change with respect to the fluctuation of the gap with the encoder magnet, the output of the MR sensor is monitored while monitoring the output of the MR sensor as proposed in Japanese Patent Application Laid-Open No. 10-166628. In many cases, gap adjustment is performed.

[0006]

However, as proposed in Japanese Patent Application Laid-Open No. Hei 10-166628, the position of the MR sensor is adjusted and the gap is adjusted while monitoring the output of the MR sensor. In this case, a large amount of adjustment time and equipment are required during the assembly work of the lens unit.

The structure around the conventional moving lens group is as follows.
As shown in FIG. 5A of the present application, the magnetizing surface 214a of the encoder magnet 214 and the positioning surface 214 with respect to the movable lens frame 205 holding the movable lens group.
b is different, and the magnetized surface 214a and the positioning surface 214b may not be parallel. In this case, the parallelism between the magnetized surface 214a of the encoder magnet 214 and the positioning reference surface 205a of the sleeve of the moving boundary frame 205 is likely to be shifted, and when the encoder magnet 214 moves together with the movable mirror frame 205, On the other hand, the gap between the magnetized surface 214a of the encoder magnet 214 and the magnetic sensing surface of the MR sensor 216 changes by the above-mentioned parallelism shift.

As a result, even if the gap amount is adjusted by adjusting the position of the MR sensor 216,
As shown in FIG. 5A, when the movable lens frame 205 moves, the gap amount between the encoder magnet 214 and the MR sensor 216 changes, so that the output characteristics fluctuate. Moreover, it is difficult to correct the variation by control, and a deviation occurs between the actual lens movement position and the control position.

The same applies to the case where the MR sensor 216 is adjusted so as to be parallel to the magnetized surface 214a of the encoder magnet 214, as shown in FIG.

[0010]

According to the present invention, a movable member movable in a predetermined direction is provided.
An encoder magnet positioned and held by the movable member, and a magnetic sensing type of magnetic sensor which is disposed opposite to the magnetized surface of the encoder magnet and outputs an electric signal corresponding to a change in magnetism accompanying the movement of the encoder magnet in the predetermined direction. In a device or an optical device having a position detection sensor, the encoder magnet may be positioned relative to the magnetized surface of the encoder magnet with a gap between the movable member and a surface of the encoder magnet opposite to the magnetized surface. Positioning is performed with respect to the movable member so that the magnetic sensing surface of the detection sensor is substantially parallel to the predetermined direction.

That is, the surface of the encoder magnet opposite to the magnetized surface is not used as the surface for positioning the encoder magnet with respect to the movable member, and the space between the opposite surface and the movable member is made larger. By positioning the encoder magnet with respect to the movable member, the magnetized surface of the encoder magnet is positioned above the magnetic sensing surface of the position detection sensor due to the space for the above-described space when assembling the device. It is possible to adjust the position of the encoder magnet so as to be substantially parallel in the direction, and to install the encoder magnet at a position where a part of the magnetized surface comes into contact with a positioning reference surface provided on the movable member.

Thus, regardless of the component accuracy of the encoder magnet (the accuracy of the parallelism between the magnetized surface and the surface opposite thereto), the position detection sensor and the encoder magnet when the encoder magnet moves together with the movable member are moved. A change in the gap amount can be almost eliminated, and a change in the output characteristics of the position detection sensor due to the change in the gap amount can be prevented.

[0013]

(First Embodiment) FIG. 1 shows the entire configuration of a zoom lens barrel according to a first embodiment of the present invention.

The zoom optical system in the zoom lens barrel is a rear focus optical system composed of four groups of convex, concave, convex and convex in order from the object side.

In FIG. 1, reference numeral 1 denotes a fixed lens barrel for holding a first group of fixed lens groups. Reference numeral 2 denotes a second group holding frame for holding the variable power lens group which is the second group, and a sleeve portion 2a.
And a U-shaped groove 2b are formed. The sleeve portion 2a and the U groove portion 2b are movably engaged with the guide bars 8 and 9, respectively.
Can be moved substantially in the optical axis direction while being guided.

Reference numeral 3 denotes an aperture unit, which controls the amount of light by driving aperture blades 3b and 3c by a driving unit 3a.

Reference numeral 4 denotes a third-group holding frame for fixedly holding the third group, which is the afocal lens group. Reference numeral 5 denotes a fourth group holding frame (movable member) for holding a correction lens group also serving as a focus group, which is a fourth group, and has a sleeve portion 5a and a U groove portion 5b. The sleeve portion 5a and the U-groove portion 5b are movably engaged with the guide bars 9 and 8, respectively, so that the fourth group holding frame 5 moves substantially in the optical axis direction while being guided by the guide bars 8 and 9. Can be.

A rack member 7 is attached to the second group holding frame 2, and the rack member 7 is engaged with a thread provided on an output shaft of a stepping motor 19 as a driving source. For this reason, when the stepping motor 19 rotates, the second group holding frame 2 is driven substantially in the optical axis direction by the meshing action between the screw portion and the rack member 7.

The second-group holding frame 2 is provided with a light-shielding portion 2c. The light-shielding portion 2c shields light between the light-emitting portion and the light-receiving portion of the photo sensor 15, so that the second-group holding frame 2 is formed. It is detected whether or not it is located at the reference position. And 2
The group holding frame 2 moves the stepping motor 1 from this reference position.
The drive position is controlled by the number of drive pulses given to 9.

Reference numeral 6 denotes a holder barrel, which is a CCD 18 serving as an image pickup device and an infrared cut and low-pass filter 17.
Is fixedly held.

An air-core coil 10 is fixed to the fourth group holding frame 5. When the coil 10 is energized, the yoke 11, the magnet 12 and the yoke 13 fixed and held by the holder barrel 6 are formed. By the action of the magnetic circuit, the fourth group holding frame 5 is driven substantially in the optical axis direction.

Here, the initial position of the fourth-group holding frame 5 is determined by abutment between the fourth-group holding frame 5 and the holder barrel 6, and from this position detection and drive control of the fourth-group holding frame 5 are performed. When the encoder magnet 14 positioned and held by the fourth-group holding frame 5 moves with respect to the MR sensor 16, a change in the magnetic force (or a change in the magnetic intensity) acting on the MR sensor 16 causes the encoder magnet 14 to move from the MR sensor 16. This is performed based on the output signal.

The MR sensor 16 has a two-phase sine wave output having a phase difference of 90 deg, and determines the moving amount and the moving direction of the encoder magnet 14 (that is, the fourth group holding frame 5) based on these two-phase outputs. be able to.

However, the output of the MR sensor may be three or more phases. Also, the phase angle may be an angle other than 90 deg.

FIG. 2 shows the change in the output of the MR sensor 16 and 4
The outline of the position control of the group holding frame 5 is shown. FIG. 2 (A)
As shown in (1), the MR sensor 16 outputs a two-phase sine wave having a phase difference of 90 deg due to the change in S and N of the encoder magnet 14.

Assuming that these two phases are A-phase and B-phase and their outputs are A and B, a microcomputer (not shown) in the camera provided with the zoom lens barrel according to the present embodiment is shown in FIG.
As shown in (B), the inverted output of each of the A and B phases
Create A, -B.

Further, as shown in FIG. 2C, the microcomputer cuts out only a substantially straight line portion up to the intersection of the outputs A, B, -A, and -B, and obtains a so-called sawtooth wave output.

Then, the microcomputer determines the moving amount and the moving direction of the fourth group holding frame 5 based on the number of the sawtooth waveforms from the initial position and the output value.

Next, a structure for holding the encoder magnet 14 with respect to the fourth group holding frame 5 will be described with reference to FIG.

As shown in FIG. 3, the MR sensor 16 is formed by insert-molding a sensor portion 20 having a magnetic sensing surface 20a in a case portion of a mold. In the insert type structure, the surface of the die that receives the magnetic sensing surface 20a of the sensor unit 20 and the surface of the die that forms the mounting surface 16a are the same plane, and the positional accuracy of the sensor from the mounting surface 16a is different. Has been improved.

Further, the encoder magnet 14 is mounted on the sleeve 5 of the fourth group holding frame 5 with the encoder magnetized surface 14a.
The sleeve portion 5a is parallel to the central axis XX of the bar fitting holes 5c and 5d formed in the sleeve a and is substantially parallel to the magnetic sensing surface 20a of the MR sensor 16 while maintaining a predetermined gap. In order to allow the positioning adjustment, the positioning adjustment is allowed between the sleeve portion 5a and a surface 14b of the encoder magnet 14 opposite to the encoder magnetized surface 14a (hereinafter referred to as a back surface). A sufficient size (height) interval t is provided.

That is, the sleeve portion 5a does not receive the back surface 14b of the encoder magnet 14, and does not have a reference surface for positioning the encoder magnet 14 by abutting the back surface 14b. However, by positioning one end surface of the encoder magnet 14 in the optical axis direction against one end surface of the sleeve portion 5a in the same direction, positioning of the encoder magnet 14 in the optical axis direction with respect to the sleeve portion 5a is performed.

The encoder magnet 14 is positioned and adjusted as described above by an external jig (not shown) when assembling the lens barrel, and is fixed and held to the sleeve portion 5a with an adhesive such as a UV curing type.

At this time, the adhesive wraps around the space between the sleeve portion 5a and the back surface 14b of the encoder magnet 14 to improve the adhesive strength.

By positioning and fixing the encoder magnet 14 with respect to the sleeve 5a in this manner, regardless of the component accuracy of the encoder magnet 14 (the accuracy of the parallelism between the encoder magnetized surface 14a and the back surface 14b). Magnetic sensing surface 20a of MR sensor 16 when encoder magnet 14 moves together with fourth group holding frame 5
And the encoder magnetized surface 14a of the encoder magnet 14
, The change in the sensor output characteristic due to the change in the gap amount can be prevented, and the high-precision position detection and position control of the fourth-group holding frame 5 (that is, the correction lens group) can be performed. It can be performed.

In this embodiment, since the encoder magnet 14 is positioned and adjusted with respect to the sleeve portion 5a of the fourth group holding frame 5, the adjustment at the component level is possible.
The lens barrel is easy to assemble.

(Second Embodiment) FIG. 4 shows a second embodiment of the present invention.
4 illustrates a structure for holding an encoder magnet with respect to a fourth group holding frame in a zoom lens barrel according to an embodiment.

The basic structure of the zoom lens barrel according to the present embodiment is the same as that of the first embodiment.

In this embodiment, both ends of the encoder magnetized surface 14a of the encoder magnet 14 are abutted against the sleeve portion 105a of the fourth group holding frame 105,
The encoder magnetization surface 14a is parallel to the central axis XX of the bar fitting holes 105c and 105d of the sleeve portion 105a, and
Positioning reference surfaces 105e, 105e for positioning the encoder magnet 14 so as to be substantially parallel to the magnetic sensing surface 20a of the MR sensor 16 while maintaining a predetermined gap.
05f.

Also in this embodiment, when the encoder magnet 14 is positioned with respect to the sleeve 5a by the positioning reference surfaces 105e and 105f, there is a gap between the sleeve 105a and the back surface 14b of the encoder magnet 14. An interval t is provided.

In such a structure, when assembling the lens barrel, the positioning reference surface 105e,
The encoder magnet 14 is assembled so that both ends of the encoder magnetized surface 14a of the encoder magnet 14 abut on 105f. The interval t has a sufficient size (height) for performing the work of assembling the encoder magnet 14.

After the encoder magnet 14 is assembled into the sleeve portion 105a, the encoder magnet 14 is fixed and held on the sleeve portion 105a with an adhesive such as a UV curing type. At this time, the adhesive wraps around the space between the sleeve portion 105a and the back surface 14b of the encoder magnet 14 to improve the adhesive strength.

By positioning and fixing the encoder magnet 14 with respect to the sleeve portion 105a in this manner, regardless of the component accuracy of the encoder magnet 14 (the accuracy of the parallelism between the encoder magnetized surface 14a and the back surface 14b). Encoder magnet 14 is 4th group holding frame 1
05, the gap between the magnetic sensing surface 20a of the MR sensor 16 and the encoder magnetized surface 14a of the encoder magnet 14 can be almost eliminated, and the variation in sensor output characteristics due to the gap change can be prevented. Thus, highly accurate position detection and position control of the fourth group holding frame 105 (that is, the correction lens group) can be performed.

In each of the above embodiments, the MR sensor 1
The output voltage of each phase of the MR sensor 16 may have a difference due to the dimensional accuracy of the mounting portion 16a of FIG. 6, but this problem can be easily solved by performing gain adjustment or the like by an amplifier for each phase. it can.

In each of the above embodiments, the lens barrel of the camera has been described. However, the present invention is an apparatus other than the lens barrel, and requires highly accurate position detection and position control of the movable member. The present invention can also be applied to various types of devices.

[0046]

As described above, according to the present invention,
The encoder magnet is moved so that the surface opposite to the magnetized surface of the encoder magnet is not positioned as the positioning surface of the encoder magnet with respect to the movable member, so that there is a gap between the opposite surface and the movable member. Because it is configured to be positioned with respect to the member,
By providing the space for the above-described interval, the encoder magnet is positioned and adjusted so that the magnetized surface of the encoder magnet is substantially parallel to the magnetic sensing surface of the position detection sensor in a predetermined direction, or the positioning provided on the movable member is performed. An encoder magnet can be incorporated at a position where a part of the magnetized surface contacts the reference surface.

Therefore, regardless of the component accuracy of the encoder magnet (the accuracy of the parallelism between the magnetized surface and the opposite surface), the gap between the position detection sensor and the encoder magnet when the encoder magnet moves with the movable member. A change in the amount can be substantially eliminated, and a change in output characteristics of the position detection sensor due to a change in the gap amount can be prevented. For this reason, highly accurate position detection and position control of the movable member can be performed.

Further, since the number of components for defining the gap between the position detection sensor and the magnetized surface of the encoder magnet is minimized, the fluctuation of the sensor output due to the accuracy of the components is small and the adjustment is easy.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a zoom lens barrel according to a first embodiment of the present invention.

FIG. 2 is a diagram for explaining an output of an MR sensor used in the zoom lens barrel of the first embodiment and an outline of position control of a lens holding frame.

FIG. 3 is a detailed view around the MR sensor.

FIG. 4 is a detailed view around an MR sensor used in a zoom lens barrel according to a second embodiment of the present invention.

FIG. 5 is a detailed view around a conventional MR sensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fixed lens barrel 2 2nd group holding frame 3 Aperture unit 4 3rd group holding frame 5 4th group holding frame 6 Holder barrel 7 Rack member 8, 9 Guide bar 10 Coil 11, 13 Yoke 12 Magnet 14 Encoder magnet 14a Encoder magnetized surface 14b Back surface 15 Photo sensor 16 MR sensor 20a Magnetic sensing surface 17 Infrared cut and low pass filter 18 CCD 19 Stepping motor

Claims (8)

[Claims] A movable member movable in a predetermined direction; an encoder magnet positioned and held by the movable member; and an encoder magnet positioned opposite to a magnetized surface of the encoder magnet for moving the encoder magnet in the predetermined direction. A device having a magnetic sensing type position detection sensor that outputs an electric signal in accordance with the accompanying change in magnetism, wherein the encoder magnet has a surface opposite to a magnetized surface of the encoder magnet and the movable member. In a state where there is an interval between the movable member and the movable member, the magnetized surface of the encoder magnet is substantially parallel to the magnetic sensing surface of the position detection sensor in the predetermined direction. An apparatus having a position detection sensor as a feature. 2. The apparatus according to claim 1, wherein the distance is set when the apparatus is assembled.
2. The method according to claim 1, wherein the encoder magnet has a size that allows a positioning adjustment of the encoder magnet so that a magnetized surface of the encoder magnet and a magnetic sensing surface of the position detection sensor are substantially parallel in the predetermined direction. An apparatus having the position detection sensor according to claim 1. 3. A part of the magnetized surface of the encoder magnet is brought into contact with the movable member so that the magnetized surface and the magnetic sensing surface of the position detection sensor are substantially parallel in the predetermined direction. A reference surface for positioning is provided, and the gap has a size that allows the incorporation of the encoder magnet into a position where a part of the magnetized surface contacts the reference surface during assembly of the device. An apparatus having the position detection sensor according to claim 1. 4. The position detection sensor according to claim 1, wherein an adhesive for fixing the encoder magnet to the movable member is inserted into the gap. apparatus. 5. A movable member that holds an optical element and is movable in a predetermined direction, an encoder magnet positioned and held by the movable member, and an encoder magnet that is disposed to face a magnetized surface of the encoder magnet, and An optical device comprising: a magnetic sensing type position detection sensor that outputs an electric signal in response to a change in magnetism accompanying movement in a predetermined direction, wherein the encoder magnet is opposite to a magnetized surface of the encoder magnet. In a state where there is an interval between the surface of the movable member and the movable member, the magnetized surface of the encoder magnet may be substantially parallel to the magnetic sensing surface of the position detection sensor in the predetermined direction. An optical device characterized by being positioned with respect to the optical device. 6. The apparatus according to claim 6, wherein the distance is set when the apparatus is assembled.
6. The method according to claim 5, wherein the encoder magnet has a size that allows a positioning adjustment of the encoder magnet such that a magnetized surface of the encoder magnet and a magnetic sensing surface of the position detection sensor are substantially parallel in the predetermined direction. The optical device according to any one of the preceding claims. 7. A part of the magnetized surface of the encoder magnet is brought into contact with the movable member so that the magnetized surface and the magnetic sensing surface of the position detection sensor are substantially parallel in the predetermined direction. A reference surface for positioning is provided, and the gap has a size that allows the incorporation of the encoder magnet into a position where a part of the magnetized surface contacts the reference surface during assembly of the device. The optical device according to claim 5, wherein: 8. The optical device according to claim 5, wherein an adhesive for fixing the encoder magnet to the movable member is inserted into the gap.