JP7039027B2 - Lens barrel - Google Patents

Description

The present invention relates to a position detecting device for detecting the position of an object, and more particularly to a lens barrel of a still camera, a video camera, or the like equipped with a position detecting device using a magnetoresistive (MR) element.

Lens barrels used in still cameras, video cameras, etc. detect the movement and position of the lens during zoom operation or focus operation, convey focal length information and shooting distance information to the photographer, and are mounted on the camera. It is known that it can be applied to various functions to realize precise movements. At this time, when the motor itself used for moving the lens does not have position information, or when the lens is moved manually, a position detecting means is required.

A magnetoresistive element is known as a position detecting means in a lens barrel. The magnetoresistive element is an element that utilizes the phenomenon that the magnetic resistance value changes when a magnetic field is applied to a semiconductor thin film such as indium antimonide (InSb). A position detecting device using this kind of magnetoresistive element is widely used for position detection of the magnetic recording medium in combination with a magnetic recording medium such as ferrite or a plastic magnet.

This type of position detection device is disclosed in, for example, Patent Document 1, which is a patent application filed by the applicant. In the invention disclosed in Patent Document 1, the magnetic sheet, the magnetic sensor, and the magnetic sensor are supported in a magnetic detection configuration in which a magnetic sensor slides on the surface of a strip-shaped magnetic sheet magnetized at a predetermined pitch to perform detection. It has a structure consisting of a magnetic sensor, a pressure spring that urges the surface of the magnetic sheet, and a protective plate.

By adopting such a structure, the distance between the magnetic sheet and the magnetic sensor is kept constant, and the protective plate protects the pressure spring and prevents the pressure spring from being deformed at the time of assembly or impact. ..

Japanese Unexamined Patent Publication No. 2013-003311

However, in the position detection device having the above-mentioned configuration, there is a problem that a frictional noise may be generated when the magnetic sheet and the magnetic sensor slide relatively.

Fricatives are classified into two types: low sound pressure levels and high sound pressure levels called squealing sounds with sinusoidal waveforms. The cause of the squeal is self-excited vibration due to friction, and noise is generated when the frequency of self-excited vibration is in the audible range. Here, it is known that when self-excited vibration occurs, the frequency of self-excited vibration and the natural frequency of the pressurizing spring almost match. The natural frequency of the pressure spring is derived from the shape of the pressure spring, but it is difficult to change the shape significantly in order to suppress the squealing sound in a space with a limited space such as a lens barrel.

From the above problems, the present invention provides a lens barrel using a position detection device provided with a space-saving mechanism for suppressing frictional noise related to sliding while protecting a pressure member and maintaining position detection performance. With the goal.

The invention according to claim 1 comprises a fixing member, a pressurizing member, a wiring member, and a magnetoresistive element, a position detecting device attached to the fixing member, and a protective member provided superimposed on the position detecting device. In the gap between the rotating member that rotates with respect to the fixing member, the magnetic recording medium attached to the rotating member and magnetized with N and S poles at a predetermined pitch, and the pressurizing member and the protective member. A lens having an impact damping member to be filled and detecting the position of the rotating member with respect to the fixing member by detecting the amount of movement of the magnetic recording medium by the magnetoresistive element pressurized by the pressurizing member. In the lens barrel, the sensitive surface of the magnetoresistive element is provided facing the magnetic recording medium, the protective member is arranged so as to cover the contour of the pressurizing member, and the impact damping member is the protective member. The lens barrel is characterized in that it comes into contact with the pressurizing member.

The invention according to claim 2 is the lens barrel according to claim 1, wherein the impact damping member is a high-density grease, an elastic member, or a foaming material.

The invention according to claim 1 is characterized in that the area of the impact damping member in contact with the protective member and the pressurizing member is smaller than the area of the protective member and the pressurizing member. The lens barrel according to 2.

According to the present invention, it is possible to provide a lens barrel using a position detection device provided with a space-saving mechanism for suppressing frictional noise related to sliding while protecting a pressure member and maintaining position detection performance. can.

It is a perspective view which shows the lens barrel in the Example of this invention. It is a developed view which shows the lens barrel in the Example of this invention. It is a top view which shows the sensor unit in an Example of this invention. It is a top view which shows the protection plate in an Example of this invention. It is sectional drawing which looked at the lens barrel in the Example of this invention from the front. It is sectional drawing which looked at the lens barrel in the Example of this invention from the side.

Hereinafter, the best mode for carrying out the present invention will be described with reference to the accompanying drawings. The present invention is not limited to this embodiment.

First, the structure of the position detection device of the present invention will be described with reference to each component. FIG. 1 is a perspective view of a lens barrel 100 to which the position detection device of the present invention is applied, in which an end portion of a sensor unit 5 attached to a fixed cylinder 1 faces a magnetic tape 9 attached to a scale ring 3. However, the structure for detecting the movement is shown.

FIG. 2 is a developed view of the lens barrel 100 to which the position detection device of the present invention is applied, and is a fixing screw 13 together with a protective plate 7 in which the sensor unit 5 sandwiches the damper 23 in the fixed cylinder 1 and is a protective member. Is concluded by. Further, the sensor unit 5 is also fastened to the fixed cylinder 1 by a holding screw 11 which is a fastening member.

The fixed cylinder 1 is a fixing member that does not rotate at the time of photographing, and holds a lens frame for holding a lens inside, a motor (not shown) used for focus drive, and various sensors. The fixed cylinder 1 is manufactured by performing an oxidized surface treatment on a machined aluminum alloy, but may be molded from an engineering plastic such as polycarbonate. A mounting base 1z to which the sensor unit 5 is mounted is integrally formed on the side surface of the fixed cylinder 1, but another member may be mounted. Holes 1a and 1b for mounting the sensor unit 5 and the protective plate 7 with the fixing screws 13 are provided on the top of the flat surface of the mounting base 1z. Further, a hole 1c for mounting the sensor unit 5 with the holding screw 11 is provided in the vicinity of the mounting base 1z.

The scale ring 3 is a rotating member that rotates during shooting, is connected to a motor (not shown) used for focus drive, and is connected to a focus lens frame (not shown) while rotating and sliding on the surface of the fixed cylinder 1. Is moved in the direction of the optical axis. That is, by detecting the amount of rotation of the scale ring 3, the position information of the lens to be detected can be calculated. The scale ring 3 is manufactured by performing an oxidized surface treatment on a machined aluminum alloy, but may be molded from an engineering plastic such as polycarbonate. Further, a band-shaped sticking surface 1e is formed at the rear end of the scale ring 3, and the magnetic tape 9 is stuck with an adhesive tape or an adhesive.

As shown in FIG. 3, the sensor unit 5 which is a position detection device is a flexible printed board (FPC) 17 which is a wiring member, an MR sensor 21 which is a magnetoresistive element, and a pressurizing member. It is composed of a pressure spring 19 of. First, the MR sensor 21 is mounted on the back surface of the tip portion 17h of the FPC 17 by a known electronic component mounting means, and is further attached to the pressure spring 19 on the back surface of the MR sensor 21 and the back surface of the central portion 17g of the FPC 17. That is, even if the tip of the pressure spring 19 bends to press the MR sensor 21 against the magnetic tape 9, the FPC 17 does not peel off from the pressure spring 19.

The pressure spring 19, which is a pressure member, is attached by fastening the holes 19a and 19b together with the protective plate 7 to the holes 1a and 1b provided in the mounting base 1z of the fixed cylinder 1 by the fixing screws 13. .. As a result, the MR sensor 21 attached to the tip portion 19f is held in a state of being pushed out from the fixed cylinder 1. The pressure spring is made of an extremely thin and flexible spring material, and even if the MR sensor 21 slides on the magnetic tape 9, it does not damage each other and has elasticity enough to always follow the movement of the magnetic tape 9. It has a structure.

As shown in FIG. 4, the protective plate 7 which is a protective member is attached to the fixed cylinder 1 by inserting the fixing screw 13 into the holes 7a and 7b together with the sensor unit 5. The contour of the protective plate 7 is substantially the same as or slightly larger than that of the pressure spring 19, and has a shape that covers the entire pressure spring 19. Further, the protective plate 7 is formed by pressing a thin plate of aluminum alloy or stainless steel, and has sufficient strength.

As shown in FIGS. 2, 5 and 6, the damper 23, which is an impact damping member, is arranged so as to fill the gap between the pressure spring 19 and the protective plate 7. The contour of the damper 23 is smaller than the pressure spring 19 and the protective plate 7, and is shaped so as to be covered by the protective plate 7. Further, the damper 23 comes into contact with both the front surface of the pressure spring 19 and the back surface of the protective plate 7. In this embodiment, the damper 23 is a high-viscosity, low-fluidity grease. The damper 23 is usually adhered to the pressure spring 19 and the protective plate 7 while maintaining its shape, and has a property of being deformed by an impact.

The magnetic tape 9, which is a magnetic recording medium, is a recording medium in which a powdery magnetic material is applied or vapor-filmed on a tape-shaped film with a binder (adhesive) at a pitch of several tens of μm on a black glossy surface. The S pole and the N pole are alternately magnetized. The surface is smooth, and the MR sensor 21 can slide on the surface without resistance. An adhesive surface is formed on the back surface, and the adhesive surface is attached to the band-shaped adhesive surface 1e formed at the rear end of the scale ring 3 (FIG. 2).

The holding screw 11 and the fixing screw 13, which are fastening members, are general screws used for fastening parts, and have an optimum number of threads depending on the material, thickness, required fastening strength, etc. of the fastening portion. Various thread groove shapes, diameters and pitches are used. Further, depending on the portion to be fastened, a screw such as a tapping screw or a reverse screw may be used. In the figure, the screw thread is not shown for convenience, but a general screw is shown, and the present invention is not limited to this.

As shown in FIG. 6, the covering 15 which is an external member is attached in the outer diameter direction of the sensor unit 5, and protects the internal mechanism from foreign substances such as dust and water droplets and impact. On the other hand, due to the smaller diameter of the lens barrel due to the miniaturization of the image pickup device in recent years, the clearance between the cover ring 15 and the protective plate 7 is extremely small, and the inside of the cover ring 15 easily comes into contact with the protective plate 7 during assembly. Is. For example, when a strong impact is applied to the covering 15 due to dropping or the like, it is conceivable that the covering 15 is deformed and protrudes inward. Even in such a case, since the protective plate 7 covers the pressure spring 19, the deformed covering 15 does not touch the pressure spring 19, and the original performance can be maintained.

As shown in FIG. 3, the flexible printed circuit board (FPC) 17, which is a wiring member, has an MR sensor 21 mounted on the tip portion 17h. Further, the tip portion 17h and the central portion 17g are adhered to the pressure spring 19. With such a configuration, even if the pressure spring 19 is curved, the FPC 17 can move integrally with the pressure spring 19 without peeling or breaking. Further, the FPC 17 is fastened to the fixed cylinder 1 with the pressing screw 11 by the hole portion 17c provided in the intermediate portion thereof. As a result, even if the lens barrel 100 moves in the optical axis direction along with the zoom drive and the focus drive and a force for pulling the FPC 17 acts in the direction of the terminal portion 17d, the FPC 17 is pulled and the pressure spring 19 warps. The MR sensor 21 is not separated from the magnetic tape 9 to break the contact. Further, the terminal portion 17d of the FPC 17 is inserted into a connector provided on the main substrate (not shown) of the lens barrel 100 and electrically connected. The FPC 17 has a structure in which a conductor foil (mainly copper) having a thickness of several tens of μm is sandwiched between film-shaped insulators (mainly a polyimide film) having the same thickness, and is highly flexible and can be repeatedly bent. Has strength that does not lose continuity.

Next, the mechanism related to noise suppression, which is a feature of the present invention, will be described. As described above, the pressure spring 19 self-excited vibration due to the frictional force when the MR sensor 21 and the magnetic tape 9 slide. Here, when the frequency of self-excited vibration is in the audible range, a squealing sound is generated. Therefore, in the present invention, a damping force is applied by filling the gap between the pressure spring 19 and the protective plate 7 with the damper 23, and the pressure spring 19 is configured so that self-excited vibration cannot occur.

ただし、
ｖｓ（ｔ）：ＭＲセンサ２１の振動速度
ω：ＭＲセンサ２１の固有周波数
Ａ、θ：初期条件によって決まる定数
γ：減衰係数
ｍ：ＭＲセンサ２１の質量
ｆ（ｖｒ）：ＭＲセンサ２１と磁気テープ９の摩擦力
である。 First, the influence of the damper 23 on the self-excited vibration will be described. When the MR sensor 21 is moved on the magnetic tape 9 at a speed of V0, the self-excited vibration is expressed by the following equation.

However,
vs (t): Vibration speed of MR sensor 21 ω: Natural frequency A of MR sensor 21, θ: Constant determined by initial conditions γ: Attenuation coefficient m: Mass of MR sensor 21 f (vr): MR sensor 21 and magnetic tape The frictional force of 9.

The frequency of self-excited vibration is √ (ω ^ 2-γ ^ 2), but since γ is sufficiently smaller than ω, the value is close to the natural frequency ω of the MR sensor 21. Further, the frictional force f (vr) changes depending on the relative speed vr between the MR sensor 21 and the magnetic tape 9.

From the equation (1), when the damping coefficient γ is negative, that is, when the velocity derivative f'(v0) of the frictional force f is negative, the vibration velocity vs (t) of the MR sensor 21 becomes the oscillation condition and self-excited vibration occurs. Resulting in. Therefore, if the damping coefficient γ is always positive, self-excited vibration cannot occur. When a damper 23 having a viscous damping coefficient C is filled between the pressure spring 19 and the protective plate 7 and a damping force is applied to the pressure spring 19, the damping coefficient γ is expressed by the equation (3).

Here, if the viscosity damping coefficient C of the damper 23 is set as in the equation (4), the damping coefficient γ is always positive even when the velocity differential f'(v0) of the frictional force f is negative. Therefore, it is possible to configure the structure so that self-excited vibration does not occur due to the damping force of the damper 23.

FIG. 6 is a cross-sectional view of a lens barrel to which the present invention is applied. The protective plate 7 is once bent at the central portion 7i, and has a shape that extends parallel to the surface of the fixed cylinder 1 again. The central portion 7i is near the base point where the tip portion 19f of the pressure spring 19 curves. The protective plate 7 is bent in the radial direction and is slightly separated from the pressure spring 19, and the gap between the protective plate 7 and the pressure spring 19 is filled with a damper 23. In addition, in FIG. 6, in order to clarify the configuration, the dimensions and the like are changed from those of other figures.

Since the damper 23 is adhered to the surface of the pressure spring 19, it moves following the bending deformation of the pressure spring 19 due to sliding. However, at this time, since the damper 23 is also adhered to the protective plate 7 fixed by the fixing screw 13 without being deformed by the impact, the upward movement is restricted. Therefore, the damper 23 is deformed by contracting in the vertical direction and expanding in the horizontal direction due to the upward load due to the bending deformation of the pressure spring 19. With the deformation of the damper 23, the impact due to sliding is damped, and the vibration amount of the bonded pressure spring 19 is further reduced.

As described above, the damper 23 damps the impact related to the sliding, so that the vibration amount of the pressure spring 19 can be reduced and the squealing can be suppressed. Further, since the damper 23 is filled in the space that should be originally a gap, it is not necessary to newly occupy the space in the lens barrel 100, so that the mechanism according to the present invention has a space-saving configuration. ..

Here, the area filled with the high-density grease used as the damper 23 needs to be within a range that does not overflow from the pressure spring 19 and the protective plate 7 even if it shrinks during sliding. This is because if it overflows to the outside, grease will be attached to the surrounding members, which may adversely affect the movement of the entire mechanism. Therefore, in the present invention, the area of contact between the damper 23 and the pressure spring 19 and the area of contact between the damper 23 and the protective plate 7 are configured to be smaller than the area of the pressure spring 19 and the protective plate 7. The area for filling the grease may be appropriately adjusted by the designer within a range that satisfies the effects of the present invention after satisfying the above restrictions.

Further, although high-density grease is used as the damper 23 in this embodiment, another substance that is a high-density paste-like substance may be used. Further, a solid object may be used as long as it is a material that deforms and shrinks when a load is applied. For example, an elastic member such as a microcell polymer sheet or a foaming material such as natural rubber can be adopted. When a solid object is used as the damper 23, the damper 23 may be sandwiched between the front surface of the pressure spring 19 and the back surface of the protective plate 7, or may be adhered with an adhesive or the like. It should be noted that the low-concentration grease does not maintain its shape and flows out from the pressure spring 19 and the protective plate 7, so that it is not suitable as a damper 23.

That is, the present invention uses a position detection device provided with a space-saving mechanism for suppressing frictional noise related to sliding while preventing deformation of the pressurizing member at the time of assembly or impact and maintaining position detection performance. The purpose of providing the lens barrel is particularly provided to be composed of a fixing member, a pressurizing member, a wiring member, and a magnetoresistive element, and a position detecting device attached to the fixing member and a position detecting device superimposed on the position detecting device. A protective member, a rotating member that rotates with respect to the fixing member, a magnetic recording medium attached to the rotating member and magnetized with N and S poles at a predetermined pitch, the pressurizing member, and the protective member. A lens barrel having a shock damping member filled in the gap of the magnetic resistance element, and detecting the position of the rotating member with respect to the fixing member by detecting the amount of movement of the magnetic recording medium. The sensitive surface of the magnetoresistive element is provided so as to face the magnetic recording medium, the protective member is arranged so as to cover the contour of the pressurizing member, and the impact damping member is the protective member and the pressurizing member. It was realized by the configuration of the lens barrel, which is characterized by contact.

The lens barrel according to the present invention is appropriately deformed and enlarged / reduced according to the image pickup apparatus to which the present invention is applied. Further, if necessary, various deformations and changes such as a change in appearance due to a change in the external dimensions of the device and a bonding position between members can be made, but all of them are within the uniform range of the present invention.

1 Fixed cylinder 3 Scale ring 5 Sensor unit 7 Protective plate 9 Magnetic tape 11 Pressing screw 13 Fixed screw 15 Covering 17 Flexible printed board 19 Pressurized spring 21 MR sensor 23 Damper 70 Pressing plate 100 Lens lens barrel

Claims (3)

With fixing members
A position detection device consisting of a pressurizing member, a wiring member, and a magnetoresistive element, which is attached to the fixing member, and
A protective member provided superimposed on the position detection device and
A rotating member that rotates with respect to the fixing member, and
A magnetic recording medium attached to the rotating member and magnetized with N and S poles at a predetermined pitch.
It has an impact damping member that fills the gap between the pressurizing member and the protective member.
A lens barrel that detects the position of the rotating member with respect to the fixing member by detecting the amount of movement of the magnetic recording medium by the magnetoresistive element pressurized by the pressurizing member.
The sensitive surface of the magnetoresistive element is provided so as to face the magnetic recording medium.
The protective member is arranged so as to cover the contour of the pressurizing member.
The lens barrel is characterized in that the impact damping member comes into contact with the protective member and the pressurizing member.
The lens barrel according to claim 1, wherein the impact damping member is a high-density grease, an elastic member, or a foaming material. The lens barrel according to claim 1 or 2, wherein the impact damping member has an area in contact with the protective member and the pressurizing member smaller than the area of the protective member and the pressurizing member.

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