JPH08248297A - Lens barrel - Google Patents

Abstract

PURPOSE: To reduce the number of parts and assembling man-hour and to miniaturize a lens barrel by assembling a thin sensor holder by an easy method. CONSTITUTION: This lens barrel is equipped with a lens barrel where a sensor mount part 37 and a sensor hole 38 are formed, a movable lens structural body operated to move in an optical axis direction by a lens driving means inside the lens barrel and having a position detecting sensor driving means, the sensor holder 35, and a lens position detecting sensor 36 mounted on the sensor holder 35 so as to be faced to the inside of the lens barrel from a sensor hole 38. Positioning means 35J and 39K regulating opposed space between the detecting sensor 36 and the position detecting sensor driving means by abutting on the mount surface 37H of the lens barrel in a state where the sensor holder 35 is mounted on the sensor mount part 37 are integrally formed on the sensor holder 35.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens barrel provided in a video camera or the like, and more particularly, to moving a lens structure housed movably inside the barrel and provided with position detecting sensor driving means. The present invention relates to a lens barrel whose position is detected by a lens position detection sensor arranged on the lens barrel side.

[0002]

2. Description of the Related Art For example, a video camera is equipped with an autofocus mechanism for automatically focusing on a subject and an electric zoom mechanism for changing the magnification.
The autofocus mechanism and the electric zoom mechanism are achieved by a lens barrel including a focus lens and a zoom lens, which are moved in the optical axis direction by driving means inside the barrel.

In the lens barrel, a focus lens and a zoom lens are attached to a lens holder that is movably mounted on a guide shaft supported in the optical axis direction inside the lens barrel to form a lens structure. The lens structure is moved by the drive means along the guide axis. The driving means of the zoom lens structure is Wi of the lens system of the video camera.
The de end and the Tele end are determined, and the zoom lens structure is moved into the lens barrel with a large amount of movement. Therefore, the drive means of the zoom lens structure is generally composed of a stepping motor as a drive source and a zoom lens drive unit having a rotation-linear conversion mechanism for converting the rotational motion of the stepping motor into a linear motion.

On the other hand, the drive means of the focus lens structure is arranged so that the focus lens structure is responsive along the optical axis so that the subject image is formed on the image pickup surface of the CCD solid-state image pickup device arranged at the rear end of the lens barrel. Move it. For this reason,
The drive means for the focus lens structure is generally composed of a linear motor in which the coil body moves.
Specifically, the linear motor is attached to a coil frame integrally combined with the focus lens structure, a substantially cylindrical yoke body disposed on the lens barrel side, and each yoke piece of the yoke body. It is composed of a magnet.

When a drive current is supplied to the coil of the coil frame by the control output from the controller, the linear motor causes a magnetic flux to be generated between the coil and the yoke in accordance with the direction of the drive current. Further, the magnetic flux generates a magnetic propulsion force that moves the focus lens structure along the guide axis in the optical axis direction. Therefore, the focus lens structure is moved in the optical axis direction in the lens barrel by this magnetic propulsion force to form a subject image on the image pickup surface of the CCD solid-state image pickup device.

The lens barrel is provided with position detecting means for detecting a reference position in order to precisely move the above-mentioned focus lens structure in the barrel. The position detecting means is composed of an MR magnet arranged on the lens holder and a position detecting sensor mounted on a sensor holder arranged on the rear end side of the lens barrel. That is, the lens holder is integrally provided with an arm-shaped magnet mounting portion so as to approach the inner surface of the lens barrel from the outer peripheral portion, and the magnet mounting portion opposes the inner surface of the lens barrel. An MR magnet is attached. The MR magnet has N poles and S poles alternately magnetized in the optical axis direction.

On the other hand, the position detection sensor is located on the rear end side of the lens barrel which defines the reference position of the focus lens structure, and is arranged facing the moving area of the MR magnet of the lens holder. In the state where the focus lens structure is located on the rear end side in the lens barrel, the position detection sensor is operated by the facing MR magnet and sends out the detection output of the reference position. This detection output is sent to the control unit to detect the reference position of the focus lens structure. In the position detection sensor, when the focus lens structure moves,
As the R magnet passes, the N pole and the S pole are detected, and the detection output is sent to the control unit. The control unit counts the detection output to be sent, and sends the output for moving the focus lens structure from the reference position to the predetermined position with respect to the lens driving means.

[0008]

By the way, in the above-mentioned position detecting means, since the position detecting sensor is operated by the MR magnet which generates a relatively weak magnetic flux, the facing distance between the MR magnet and the position detecting sensor is set. It must be set with high precision, and is arranged on the lens barrel via the positioning means. The lens barrel movably supports a focus lens structure on a guide shaft supported in the lens barrel in the optical axis direction, and the focus lens structure is MR-supported.
The magnet is attached integrally. For this reason,
In a conventional lens barrel, an engaging portion that holds a guide shaft is integrally formed at one end of a sensor holder in which a position detection sensor is mounted, and the position detection sensor and the MR magnet are assembled by assembling the sensor holder into the lens barrel. And were positioned relative to each other with respect to the guide axis.

That is, the sensor holder is composed of a base portion on which the position detecting sensor is mounted and an arm portion projecting integrally from the base portion to face the inside of the lens barrel, and a guide shaft is provided at the tip portion of the arm portion. The above-mentioned engaging portion formed of a shaft hole having a substantially semicircular shape for hugging is formed. Further, the sensor holder is configured such that the arm portion is extended by a predetermined length in the axial direction with respect to the base portion so that the engagement portion is relatively engaged with the guide shaft at a position where the engagement portion does not interfere with the focus lens structure. There is. Therefore, each part of the sensor holder is formed with high precision and has a complicated shape as a whole. Further, the lens barrel has a slightly larger length dimension by including the sensor holder.

The sensor holder described above must be positioned and fixed with respect to the guide shaft in order to define the reference position of the focus lens structure. Therefore, in the conventional lens barrel, there is a problem in that a holder pressing member is further required to press the sensor holder, the number of parts and the number of assembling steps are increased, and it is troublesome to maintain the positioning accuracy. .

The problem with the above-mentioned positioning means is that
This is not only a problem specific to the positioning means of the focus lens structure of the autofocus mechanism mounted on the video camera, but also a problem common to the positioning means of the movable lens structure provided in the lens barrel of other devices.

Therefore, according to the present invention, the holder pressing member is not required and the assembly to the lens barrel is made possible by an extremely simple operation, so that the number of parts and the number of assembling steps can be reduced, and the structure of the sensor holder can be reduced. Proposed for the purpose of providing a lens barrel in which the position detection sensor driving means and the lens position detection sensor provided in the movable lens structure are positioned with high accuracy, which is achieved by downsizing and simplification. It was done.

[0013]

A lens barrel according to the present invention which achieves this object is a lens barrel having a sensor mounting portion and a sensor hole, and an optical axis provided inside the lens barrel by lens driving means. A movable lens structure that is housed so as to be movable along the direction and that is provided with position detection sensor driving means that is located at a reference position corresponding to the sensor hole; and a sensor holder that is mounted on the sensor mounting portion of the lens barrel When the sensor holder is mounted on the sensor mounting portion of the lens barrel, it is mounted on the sensor holder so as to be exposed to the inside from the sensor hole, and the position detection sensor driving means of the movable lens structure that moves in the lens barrel is detected. And a lens position detection sensor that operates.

The sensor holder contacts the mounting surface of the lens barrel in a state where the sensor holder is mounted on the sensor mounting portion, and defines a facing distance between the mounted lens position detection sensor and the position detection sensor driving means of the movable lens structure. The positioning means is integrally formed.

[0015]

According to the lens barrel of the present invention having the above-described structure, the lens holder is mounted on the sensor mounting portion formed on the lens barrel to mount the lens position detecting sensor on the sensor holder. Is positioned corresponding to the sensor hole, and the mounting surface of the lens barrel engages with the positioning means to oppose the lens position detection sensor and the position detection sensor driving means of the movable lens structure that is moved in the lens barrel. The interval is defined. The lens barrel has a structure in which the movable lens structure is moved to a position where the position detection sensor driving means and the lens position detection sensor face each other.
The lens position detection sensor is operated by the position detection sensor driving means to output the position information output of the movable lens structure in the lens barrel to the control unit.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the present invention will be described below with reference to the drawings. The embodiment shows a lens barrel 1 mounted on a video camera and provided with an autofocus mechanism for automatically focusing on a subject and an electric zoom mechanism for changing magnification. As shown in FIGS. 1 and 2, the lens barrel 1 includes a lens barrel 2 configured by combining a front lens barrel 3 formed in a cylindrical shape and a rear lens barrel 4 formed in a rectangular tube shape. I have it. The front lens barrel 3 has a slightly larger opening diameter than the rear lens barrel 4. In the following description, “front” means the left side in FIG. 1, and “rear” means the right side.

The front lens barrel 3 is a so-called front lens unit which constitutes the first fixed lens assembly 5 from the front side.
The fixed lens group 5, the first movable lens group that constitutes the zoom lens structure 6 of the electric zoom mechanism, and the zoom lens drive unit 7 that drives the zoom lens structure 6 are assembled. Further, in the rear lens barrel 4, a second movable lens forming a second fixed lens group 10 and a focus lens structure 11 of the autofocus mechanism via an intermediate frame 9 in which a diaphragm device 8 is incorporated from the front side. The group and are incorporated. As described above, the lens barrel 1 is composed of two fixed lens groups and two movable lens groups.
The “fixed lens group” refers to one or a plurality of lens groups that are incorporated in the lens barrel 2 without being moved in the optical axis direction during shooting, and the “movable lens group” refers to during shooting. One or a plurality of lens groups that are moved in the optical axis direction in the lens barrel 2 are referred to as lens groups.

The front lens barrel 3 is provided with an axial groove portion 3A extending from the rear end portion to the front end, and a plurality of lens barrels 1 for mounting the lens barrel 1 on the outer peripheral portion of a video camera which is a main device. The mounting portion 3B is integrally formed. A zoom lens drive unit 7 for moving the zoom lens structure 6 in the optical axis direction so as to close the groove 3A is incorporated in the front lens barrel 3. The front lens barrel 3 has a notch 3 which is located on the rear end side close to the groove 3A.
C is provided.

The rear lens barrel 4 has an assembling portion 4 in which a CCD solid-state image pickup device (not shown) is incorporated in the opening on the rear end side.
A is integrally formed. Further, the rear barrel 4 has first guide shafts 12 (12A, 12B) located at opposite corners and parallel to each other in the optical axis direction, and light located at other opposite corners. Second guide shafts 13 (13A, 13B) that are parallel to the axial direction are provided, respectively. Further, the rear lens barrel 4 has a focus lens driving means 14 for driving the focus lens structure 11.
Is provided. The rear lens barrel 4 has a lens position detecting means 34 for detecting the reference position of the focus lens structure 11.
Is provided.

One end of the first guide shaft 12 is fitted and supported in a shaft hole formed in a flange portion 4B formed by projecting at the opening of the rear lens barrel 4, and the first guide shaft 12 projects largely toward the front side. In the state in which the front barrel 3 and the rear barrel 4 are combined, the front end is fitted into a shaft hole formed in the inner surface of the front barrel 3 as shown in FIG. The zoom lens structure 6 is supported on the first guide shaft 12 so as to be movable in the optical axis direction inside the front barrel 3.

The second guide shaft 13 has one end fitted and supported in a shaft hole provided in a rear wall portion 4C constituting the CCD mounting portion 4A of the rear lens barrel 4, and the other end portion up to the front opening portion. It has been extended. The other end of the second guide shaft 13 is fitted into a shaft hole formed in the intermediate frame 9 combined with the front part. The focus lens structure 11 is supported on the second guide shaft 13 so as to be movable in the optical axis direction inside the rear lens barrel 4.

As shown in FIG. 2, the first fixed lens group 5 is composed of a first lens 5A, a second lens 5B and a third lens 5C which are bonded together. In the first fixed lens group 5, the lenses 5A to 5C are assembled at the front opening end of the front barrel 3 with their optical axes aligned with each other.

As shown in FIG. 2, the zoom lens structure 6 which constitutes the first movable lens group includes three zoom lenses 1
6 (16A to 16C) and a substantially disk-shaped lens holder 1
7 and 7. In the lens holder 17, an axial cylindrical portion 17B is integrally formed in the central portion of a disc-shaped base portion 17A, and a pair of bearing portions 17C, 1C is provided on the outer peripheral portion.
7D is integrally formed. A zoom lens 16 is incorporated in the cylindrical portion 17B so that the optical axis thereof coincides with that of the first fixed lens group 5. The bearing portions 17C and 17D are formed at positions opposed to each other by 180 ° and penetrate the first guide shaft 12, respectively. On the side surface of the base portion 17A,
A position detection piece 17E having a semicircular cross section is formed along the first bearing portion 17C.

The first bearing portion 17C is formed in an elongated tubular shape extending in the axial direction, and the zoom lens structure 6 is incorporated into the front barrel 3 via the first guide shaft 12. At a position corresponding to the groove portion 3A provided in the front lens barrel 3. The first bearing portion 17C is provided with an engaging portion 17F that integrally projects from the outer peripheral surface in a substantially concave shape. The engagement portion 17F is provided with the cutout portion 3C when the zoom lens structure 6 is located on the rear side of the front lens barrel 3.
Is located corresponding to. The second bearing portion 17D is formed as a substantially U-shaped convex portion.

As shown in FIG. 1, the zoom lens drive unit 7 includes a stepping motor 18 and a bracket member 19 in which the stepping motor 18 is assembled on one end side.
And a drive shaft 20 rotatably supported by the bracket member 19 and driven by the stepping motor 18,
The drive shaft 20 and a driver shaft 21 movably supported in the axial direction by a guide shaft (not shown).

The bracket member 19 has an outer dimension sufficient to close the groove 3A provided in the front lens barrel 3, and has a shape in which both sides are bent. The drive shaft 20 is rotatably supported on both sides of the bracket member 19 and has one end integrated with the rotation shaft of the stepping motor 18. Further, a feed screw is integrally formed on the outer peripheral portion of the drive shaft 20. The driver 21 is integrally formed with a screw portion that meshes with the feed screw of the drive shaft 20 and an engaging portion that engages with the engaging portion 17F formed on the first bearing portion 17C of the lens holder 17. ing.

The zoom lens drive unit 7 is attached to the front lens barrel 3 so as to close the groove 3A when the zoom lens structure 6 is incorporated in the front lens barrel 3. The driver 21 is the zoom lens drive unit 7
In the state where is attached to the front lens barrel 3, the engaging portion is relatively engaged with the engaging portion 17F of the lens holder 17. The zoom lens drive unit 7 is assembled to the front barrel 3 while visually observing the engagement state between the driver 21 and the engagement portion 17F from the cutout portion 3C. The cutout 3C is
After the zoom lens drive unit 7 is assembled to the front lens barrel 3, the zoom lens drive unit 7 is closed by the printed circuit board 22 on which a position detection sensor (not shown) is mounted.

The printed circuit board 22 is connected to the stepping motor 18 and a flexible cable 23 for supplying power to each part. In the state where the printed circuit board 22 is assembled to the front lens barrel 3, the position detection sensor is
The position detection piece 17E formed integrally with the lens holder 17 is composed of an optical detection sensor including a light receiving element and a light emitting element that straddle the moving area. The position detection sensor is located substantially in the center of the moving area of the zoom lens structure 6 and is attached to the front lens barrel 3, and the front lens barrel 3 has moved from the most position to the rear lens barrel 4 side. Position detection piece 17E
When the element passes between the light receiving element and the light emitting element and the elements are cut off from each other, the passage is detected by the change of the current value and the detection output is sent to the control unit. Stepping motor 18
The rotation operation is controlled by the output of the position detection sensor.

As shown in FIG. 1, the diaphragm device 8 is assembled so as to be positioned at the rear opening of the front lens barrel 3 and supported by the intermediate frame 9, and has a disk-shaped base portion 24A. The base member 24 includes a motor mounting portion 24B integrally provided on the outer peripheral portion of the base portion 24A, and a drive detection portion 25 mounted on the motor mounting portion 24B. In the base portion 24A of the substrate member 24, a diaphragm hole 24C whose optical axis coincides with that of each lens group is formed in the central portion. Further, in detail, the base portion 24A is configured by stacking two thin circular plates, and has a plurality of diaphragm blades incorporated therein. The drive detection unit 25 includes a light amount detection unit that detects the amount of light that has entered the lens barrel 25, a control unit, and an arc actuator that is operated by the control unit to drive the diaphragm blades.

In the diaphragm device 8, the rear lens barrel 4 is constructed such that the base portion 24A is combined with the recessed portion 9A of the intermediate frame 9 which will be described later.
Combined with. In the state where the diaphragm device 8 is combined with the rear lens barrel 4, the drive detection unit 25 supports the outer peripheral portion by the arcuate support ribs 4D formed on the outer peripheral wall of the rear lens barrel 4. In the diaphragm device 8, the drive detector 25 is driven by the output from the controller to drive the diaphragm blades to adjust the aperture size of the diaphragm hole 24C. The amount of light of the lens barrel 1 is adjusted by the diaphragm operation of the diaphragm device 8. Of course, the diaphragm device 8 may be composed of, for example, a diaphragm device using an electrochromic element.

The intermediate frame 9 is formed so as to have an outer dimension sufficient to close the rear opening of the front lens barrel 3, and has an inner diameter dimension sufficient to accommodate the base portion 24A of the diaphragm device 8 on the front surface portion. 9A of recesses are formed. Further, the intermediate frame 9 is provided with a lens mounting hole 9B at the center thereof in which the second fixed lens 10 is mounted so that the optical axes of the lens mounting holes 9B coincide with those of the lens groups. Although not described in detail, the intermediate frame 9 is assembled in a state in which it is aligned with the axial hole located on the outer peripheral side and penetrating the first guide shaft 12 and the front lens barrel 3 or the rear lens barrel 4, respectively. Mounting holes, positioning protrusions, positioning holes, etc. are appropriately formed. The second guide shaft 13 is
As shown in FIG. 2, the front end is supported by a bearing portion formed on the back surface of the intermediate frame 9.

As shown in FIG. 2, the focus lens structure 11 constituting the second movable lens group has two focus lenses 26 (26A, 26B) and a lens holder 27.
A coil bobbin 28 formed integrally with the lens holder 27, and an MR magnet 29 that constitutes a position detection unit.
And the like. Lens holder 27
Is a base 27A configured as a rectangular frame and the base 2
7A and a cylindrical portion 27B that is integrally formed at the central portion of 7A and to which the focus lens 26 is assembled. In the lens holder 27, the bearing portion 2 in which the second guide shaft 13 penetrates through the corner portions of the base portion 27A that face each other.
7C and 27D are integrally projected. Base 2
7A are provided with yoke holes 27E and 27F located on both sides of the tubular portion 27B and configured as rectangular holes in the height direction.

A coil portion 28A of a coil bobbin 28 having a rectangular tubular shape having a diameter larger than that of the tubular portion 27B is integrally connected to the base portion 27A so as to extend to the outer peripheral portion of the tubular portion 27B on the back side. Has been done. The coil bobbin 28 includes a coil portion 28A and a rectangular flange portion 28B that faces the base portion 27A of the lens holder 27. In other words, the base portion 27A of the lens holder 27 has the coil bobbin 2
The coil wire is wound around the outer peripheral surface of the coil portion 28A between the base portion 27A and the flange portion 28B. In addition, the tubular portion 27B includes the coil bobbin 2
It is located in the coil hole 8 and extends in the axial direction.

The coil bobbin 28 has a flange portion 28B.
The bearing portions 28C are integrally projected at the opposite corner portions. The bearing portion 28C faces the first bearing portion 27C formed on the base portion 27A on the lens holder 27 side, and the second guide shaft 13 is penetrated therethrough. Both ends of a square magnet-shaped MR magnet 29 made of a magnetic material are supported by the first bearing portion 27C and the bearing portion 28C. The MR magnet 29 has N poles and S poles alternately magnetized in the optical axis direction.
Is mounted on the rear lens barrel 4 and extends along the outer peripheral wall of the rear lens barrel 4.

The focus lens structure 11 is moved in the optical axis direction in the rear barrel 4 by using a linear motor constituted by a coil bobbin 28 around which a coil wire is wound and a focus lens driving means 14 as a drive source. The focus lens driving means 14 includes a pair of left and right yokes 30, 31.
And magnets 32 and 33 assembled to the yokes 30 and 31, respectively. These yokes 30 and 31 are bases 30A and 3 in the height direction, respectively.
1A, a pair of yoke pieces 30B, 30C and a yoke piece 31B, which face each other in parallel with each other and are bent forward.
31C is formed to have an overall U-shape.

The yoke pieces 30B and 30C and the yoke piece 31
The distance between B and 31C is slightly larger than the thickness dimension of the coil bobbin 28 forming the focus lens structure 11,
The cross-sectional shape is slightly smaller than the opening size of the opening holes of the yoke holes 27E and 27F. Also, the yoke pieces 30B and 30C and the yoke pieces 31B and 31C are the focus lens structure 11
Is larger than the axial length of the rear lens barrel 4 and is slightly smaller than the longitudinal length of the rear lens barrel 4.

The magnets 32 and 33 have a thin plate shape as a whole, and the outer yoke pieces 30B of the yokes 30 and 31 are
It is joined and fixed to the inner surface of 31B over almost the entire area in the axial direction.

In the yokes 30 and 31 constituting the focus lens driving means 14, the base portions 30A and 31A are attached to the rear lens barrel 4.
Is attached to the rear wall portion 4C of the. These yokes 30,
In the reference numeral 31, the focus lens structure 11 is the second guide shaft 1
In a state where the inner yoke pieces 30C and 31C are supported by 3 and assembled in the rear lens barrel 4, the inner yoke pieces 30C and 31C are attached to the lens holder 27.
While passing through the yoke holes 27E and 27F formed in the base portion 27A, the outer yoke pieces 30B and 31B extend close to the outer peripheral surface of the coil portion 28A of the coil bobbin 28 around which the coil wire is wound.

Therefore, the focus lens structure 11 and the focus lens driving means 14 incorporated in the rear lens barrel 4 are arranged on the yoke 30 side on the outer yoke piece 30B-magnet 32-inner yoke piece 30C-base portion 30A-outer yoke piece. It constitutes the right closed magnetic circuit of 30B. Similarly, the focus lens structure 11 and the focus lens driving means 14 are arranged on the yoke 31 side on the outer yoke piece 31B-magnet 3 side.
3-Inner yoke piece 33C-Base portion 31A-Outer yoke piece 3
It constitutes the left closed magnetic circuit of 1B.

Further, the coil portion 28A of the focus lens structure 11 cuts off these closed magnetic paths, and a drive current is supplied from a power source portion by a control portion (not shown), so that a magnetic flux corresponding to the direction of the drive current is generated. It is generated and acts on the above-mentioned closed magnetic circuit. The focus lens structure 11 is supported by the second guide shaft 13 by the magnetic thrust generated between the closed magnetic path and the coil portion 28A, and moves in the front-rear direction inside the rear barrel 4.

The focus lens structure 11 is composed of an MR magnet 29, a sensor holder 35 mounted on a sensor mounting portion 37 formed integrally with the rear lens barrel 4, and a position detection sensor 36 mounted on the sensor holder 35. The position in the lens barrel 2 is detected by the position detecting means 34. The position detection sensor 36 is a magnetic sensor whose resistance value is changed by a change in magnetic flux density. The resistance value of the position detection sensor 36 is counted by the control unit so that the lens barrel 2 of the focus lens structure 11 can be obtained.
The position inside is detected, and the current supply to the coil portion 28A is controlled.

As shown in FIGS. 3 and 4, the sensor holder 35 has a flat main surface 35A integrally formed with a sensor mounting portion 35B configured as a U-shaped standing wall. The sensor mounting portion 35B is formed. The position detection sensor 36 is fixedly bonded inside by an adhesive or the like. Position detection sensor 36
Is connected to a control unit (not shown) or the like via a flexible cable 39. The sensor holder 35 has a tapered surface 35C formed on one end side of the bottom surface so that the one end side is slightly thin, and the pair of engaging portions 35D and 35E are separated from each other in the width direction and have a tongue shape. It is projected integrally with.

The engagement surface 35D, 35E has a main surface 3
Located near the tip on the 5A side, the first engaging protrusion 35F,
35G are integrally projected. In addition, the engaging portions 35D and 35E are integrally provided with second engaging convex portions 35H and 35I, respectively, which are located near the base end portion on the bottom surface side. Further, the sensor holder 35 has a main surface 35A.
To the engaging portions 35D, 35 with the sensor mounting portion 35B interposed therebetween.
Positioning projections 35J and 35K are formed integrally with each other in a region on the side opposite to E and spaced apart in the width direction.

The sensor holder 35 configured as described above
Are the engaging grooves 37B and 37C of the engaging portion 37A in which the engaging portions 35D and 35E constitute the sensor mounting portion 37 of the rear barrel 4.
Is attached by engaging with. The sensor mounting portion 37 corresponds to the moving region of the MR magnet 29 mounted on the focus lens structure 11, and the rear lens barrel 4 is provided.
The first engaging portion 37A formed on the outer peripheral surface of the
The second engaging portion 37D and the third engaging portion 37F which are arranged in the direction orthogonal to the engaging portion 37A of the above and are parallel to each other, and the concave portion is surrounded by the engaging portions 37A, 37D, 37F. The engaging recess 37H is provided.

The first engaging portion 37A is formed as a block-shaped convex portion, and one side surface portion is provided with engaging grooves 37B and 37C spaced apart in the width direction. These engaging grooves 37B and 37C have an opening width dimension of the sensor holder 35.
The width dimensions of the engaging portions 35D and 35E are substantially equal to each other, and the opening height dimension is slightly larger than the thickness dimension of the engaging portions 35D and 35E. In addition, the engagement groove 37
B and 37C have a first engagement protrusion 35F, a second engagement protrusion 35H, and a first engagement protrusion 35G whose opening heights are formed on the front and back surfaces of the engagement portions 35D and 35E. It is made slightly smaller than the thickness dimension with the second engagement convex portion 35I.

The second engaging portion 37D and the third engaging portion 37F
Are formed such that their cross sections facing each other have an inverted L-shape, and the inner surface facing distance is substantially equal to the width dimension of the sensor holder 35. Further, the second engaging portion 37D and the third engaging portion 37F are provided with the engaging surface 37E from the engaging concave portion 37H,
The height dimension up to 37 G is almost equal to the thickness dimension of the sensor holder 35. The engagement concave portion 37H is provided on the outer peripheral surface of the rear lens barrel 4 as a concave portion having substantially the same outer dimensions as the sensor holder 35.

The rear lens barrel 4 is provided with a sensor hole 38 located in the engaging recess 37H. This sensor hole 38
Is formed as a rectangular opening in the rear barrel 4 corresponding to the moving area of the MR magnet 29, and the opening size is substantially equal to the outer size of the sensor mounting portion 35B of the sensor holder 35.

The sensor holder 35 includes a position detecting sensor 36.
The main surface 35A side on which is attached is made to face the engagement recess 37H side of the rear lens barrel 4, and the engagement portion 35A is attached as shown in FIG.
D and 35E are engaging grooves 37B and 37 of the first engaging portion 37A.
Inserted in C respectively. The sensor holder 35 is configured such that, in a state in which the engaging portions 35D and 35E are inserted into the engaging grooves 37B and 37C, the slightly thin engaging portions 35D and 35E are elastically deformed in the thickness direction to some extent. Joint convex part 3
5F and 35G are pressed against the outer peripheral surface of the rear lens barrel 4, and the second engaging protrusions 35H and 35I are attached to the first engaging portion 3.
It is pressed against the ceiling surface of 7A.

In the sensor holder 35, the main surface 35A is engaged with the engaging recesses 37 with the engaging parts 35D and 35E as fulcrums.
H, in other words, it is pressed against the outer peripheral surface of the rear lens barrel 4, and the mounted position detection sensor 36 is exposed to the inside of the rear lens barrel 4 through the sensor hole 38. The sensor holder 35 has a second
The engaging portion 37D and the third engaging portion 37F are engaged in the thickness direction by the engaging surfaces 37E and 37G, respectively, and are engaged in the width direction by the side walls of the engaging recess 37H. It is firmly attached to the sensor attachment portion 37 of No. 4 by one-touch operation.

The position detection sensor 36 is a sensor holder 35.
Is attached to the sensor mounting portion 37,
The positioning convex portions 35J and 35K contact the main surface of the engaging concave portion 37H to position the sensor holder 35, thereby accurately defining the facing interval with the MR magnet 29 that generates a relatively weak magnetic flux. The structure that defines the distance between the MR magnet 29 and the position detection sensor 36 is
For example, a positioning protrusion may be formed on the rear barrel 4 side. Further, it goes without saying that the number of positioning protrusions is not limited to two.

According to the embodiment lens barrel 1 configured as described above, the magnetism generated by supplying the drive current to the coil bobbin 28 of the focus lens structure 11 from the power supply unit controlled by the control unit (not shown) The focus lens structure 11 moves the second guide shaft 1 by the dynamic thrust.
It is supported by 3 and moves in the rear lens barrel 4. The movement of the focus lens structure 11 is performed by the MR magnet 2
The change in magnetic flux density due to 9 is detected as a change in resistance value by the position detection sensor 36 and is counted by the control unit. In the lens barrel 1, the current supply from the power supply unit is controlled by the output from the control unit, and the position of the focus lens structure 11 in the rear lens barrel 4 is controlled in the optical axis direction to perform focus adjustment.

In the lens barrel 1 of the first embodiment described above, the MR magnet 29, the sensor holder 35, the position detection sensor 36 and the sensor mounting portion 37 allow
The position detecting means 34 for detecting the position of the focus lens structure 11 in the optical axis direction is constituted, and on the zoom lens structure 6 side, a position detecting piece 17E formed along the first bearing portion 17C, a light emitting element and a light receiving element. The position detecting means is configured by an optical sensor including an element.
Therefore, it goes without saying that the position detecting means 34 described above can also be adopted as position detecting means on the side of the zoom lens structure 6.

The lens barrel 50 shown in FIG. 5 shows the second embodiment of the present invention, and is substantially the same as the position detecting means 34 of the lens barrel 1 of the first embodiment described above on the zoom lens structure 6 side. An example in which the position detecting means 55 and the sensor mounting portion 52 to which the position detecting means 55 is mounted is adopted will be shown. The zoom lens structure 6 is similar to the zoom lens structure 6 included in the lens barrel 1 of the first embodiment described above, and includes a zoom lens 16 and a substantially disk-shaped lens holder 17. The lens holder 17 has a disk-shaped base 17
An axial cylinder portion 17B in which the zoom lens 16 is incorporated is integrally formed in the central portion of A, and a pair of bearing portions 17C and 17D is integrally formed in the outer peripheral portion. The bearing portions 17C and 17D are formed at positions facing each other by 180 °, and the guide shaft 12 erected and supported by the lens barrel 4 is provided.
Are penetrated respectively. A position detecting piece 17E having a semicircular cross section is formed on the side surface of the base portion 17A along the first bearing portion 17C.
Are formed.

The magnet 51 is joined and fixed to the position detecting piece 17E. As this magnet 51, an MR magnet in which N poles and S poles are alternately magnetized in the axial direction is adopted. It should be noted that the magnet 51 need only be magnetized at one location if it is sufficient to simply detect whether or not the reference position of the zoom lens structure 6 has passed.

The lens barrel 4 is provided with a sensor mounting portion 52 for mounting a position detecting means 55 which will be described later. The sensor mounting portion 52 is composed of an engagement portion 53 having an engagement groove (not shown) formed therein, and a sensor hole 54 formed in the vicinity of the engagement portion 53. Sensor hole 54
Are opened facing the moving area of the magnet 51 joined and fixed to the position detection piece 17E of the zoom lens structure 6 that is moved in the optical axis direction by the zoom lens driving unit in the lens barrel 4.

The position detecting means 55 includes a sensor holder 56.
And a position detection sensor 57 joined and fixed to a mounting portion formed on the main surface of the sensor holder 56, and a member such as a flexible cable 61 electrically connecting the position detection sensor 57 to the control unit and the like. Has been done. The sensor holder 56 is integrally provided with an engaging portion 58, which is inserted into the engaging groove of the sensor mounting portion 52, at one end thereof. An engaging protrusion 59 is formed on the engaging portion 58.
In addition, the sensor holder 56 is integrally provided with a positioning projection 60 on a main surface located on the opposite side of the engagement portion 58 with the position detection sensor 57 interposed therebetween.

The sensor holder 56 constructed as described above
Is attached to the lens barrel 4 by inserting the engaging portion 58 into the engaging groove of the sensor attaching portion 52 such that the mounted position detection sensor 57 is positioned corresponding to the sensor hole 54. The sensor holder 56 is pressed against the entire lens barrel 4 side by the engagement convex portion 59 of the engagement portion 58 inserted into the engagement groove coming into contact with the inner wall of the sensor attachment portion 52, and the positioning convex portion 60 causes the zoom lens to move. The distance between the position detection sensor 57 and the structure 6 is defined with high accuracy. Therefore, the position detection sensor 57 reliably detects the position of the zoom lens structure 6 in the lens barrel 4 even when the magnet 51 generates a relatively weak magnetic flux.

In each of the above-described embodiments, the position detecting portion provided on the movable lens structure side is made of a magnet, and the lens position detecting sensor for detecting the detecting portion is made of a magnetic detecting sensor. Of course, the lens position detection sensor may be configured by an appropriate detection sensor such as a light detection sensor.

[0059]

As described above in detail, according to the lens barrel of the present invention, the lens position for detecting the position detecting portion provided in the movable lens structure which is moved in the optical axis direction by the lens driving means. By mounting the detection sensor on a thin and simple sensor holder and mounting the sensor holder on the lens barrel by a simple method, the number of parts and the number of assembling steps can be significantly reduced. In addition, the lens barrel, by the positioning means in the state where the sensor holder is attached to the lens barrel,
By defining the distance between the position detection unit and the lens position detection sensor with high accuracy, the position of the movable lens structure can be reliably detected, and the movable lens structure can be controlled with high accuracy.

[Brief description of drawings]

FIG. 1 is an overall exploded perspective view of a lens barrel mounted in a video camera shown as an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of a main part of the lens barrel.

FIG. 3 is a longitudinal sectional view of an essential part for explaining a configuration of a lens position detection unit which is provided in the lens barrel and detects a position of a focus lens structure in the barrel.

FIG. 4 is an exploded perspective view of a main part of the lens position detection unit.

FIG. 5 is an exploded perspective view of a main part for explaining a configuration of a lens position detection unit that detects a position of a zoom lens structure mounted in a video camera shown in a second embodiment of the present invention in a lens barrel.

[Explanation of symbols]

 1 Lens barrel 2 Lens barrel 3 Front barrel 4 Rear barrel 6 Zoom lens structure (movable lens structure) 7 Zoom lens drive unit (lens driving means) 11 Focus lens structure (movable lens structure) 12 Supports zoom lens structure First guide shaft 13 Second guide shaft that supports the focus lens structure 14 Focus lens drive means (lens drive means) 16 Zoom lens group 26 Focus lens group 29 MR magnet (position detection sensor drive means) 34 Position detection means 35 sensor holder 36 position detection sensor 37 sensor mounting portion 38 sensor hole

Claims (3)

[Claims] 1. A lens barrel in which a sensor mounting portion and a sensor hole are formed, and a lens driving means accommodates the lens barrel inside the lens barrel so as to be movable along the optical axis direction. The movable lens structure provided with the corresponding position detection sensor driving means, the sensor holder attached to the sensor mounting portion of the lens barrel, and the sensor hole when the sensor holder is attached to the sensor mounting portion of the lens barrel. It is equipped with a lens position detection sensor that is mounted on the sensor holder so as to be exposed to the inside and that detects the position detection sensor driving means of the movable lens structure that moves in the lens barrel. Drives the mounted lens position detection sensor and the movable lens structure position detection sensor by contacting the mounting surface of the lens barrel in the mounted state. A lens barrel positioning means for defining the opposing distance between the stages is characterized by being formed integrally. 2. The sensor holder is relatively engaged with an engaging groove portion forming a sensor mounting portion formed on the lens barrel, has a slightly small thickness, and has an engaging convex portion integrally formed on the main surface. The sensor holder is integrally formed with a protruding engaging portion, and the sensor holder has a lens barrel in which the engaging convex portion is elastically pressed against the inner wall of the groove while the engaging portion is engaged with the engaging groove portion. The lens barrel according to claim 1, wherein the lens barrel is attached to the lens barrel. 3. The sensor holder has a first engaging projection formed on a main surface of an engaging portion formed with a positioning means facing the sensor mounting portion of the lens barrel, and the engaging portion of the engaging portion. A second engagement protrusion is formed on the base end side of the other main surface, and the first engagement is elastically pressed against the inner wall of the groove in a state where the engagement portion is engaged with the engagement groove. The lens according to claim 1 or 2, wherein the convex portion and the second engaging convex portion elastically displace the engaging portion in a direction in which the positioning means comes into contact with the mounting surface of the lens barrel. Lens barrel.