JPH08248288A - Shaft supporting mechanism and lens barrel provided with the same - Google Patents

Abstract

PURPOSE: To easily insert a guide shaft, to improve working efficiency and to prevent lubricant from leaking to the outside of a guide bearing supporting the guide shaft coated with the lubricant by specifying the shape of the shaft hole of the guide bearing. CONSTITUTION: A focusing unit 8 is constituted of the focusing guide shafts 20A and 20B, a focusing lens driving mechanism housed in a rear lens barrel 4, and a focusing lens structural body 22 supported by the guide shafts 20A and 20B. The guide shafts 20A and 20B are wholly and uniformly coated with the lubricant whose viscocity is comparatively low such as fluorine oil, so that the slidability of the structural body 22 is secured. A focusing guide shaft hole 18C provided in a fixed lens holder 18 is formed so that the length of its diagonal may be a little larger than the shaft diameter of the guide shafts 20A and 20B, and its cross section may be polygonal, for example, regular octagonal. Therefore, in the case of inserting the guide shafts 20A and 20B to which the lubricant is stuck in the shaft hole 18C, inside air is exhausted from the shaft hole 18C and an aperture part side through a gap between the outer peripheral surfaces of the shafts 20A and 20B and the shaft hole 18C.

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 specifically, a driving current is supplied to a movable lens structure housed movably inside the barrel through a flexible printed cable. And a lens barrel which is adapted to do so.

[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 movable lens structure is constructed by assembling a focus lens and a zoom lens to a lens holder movably mounted on guide shafts supported in the optical axis direction inside the lens barrel. These lens structures are moved by the drive means along the guide axis. The drive means of the zoom lens structure determines the Wide end and the Tele end of the lens system of the video camera and moves the zoom lens structure into the lens barrel with a large amount of movement. Therefore, the drive means for this zoom lens structure is generally
The zoom lens drive unit includes a stepping motor as a drive source and a rotation-linear motion conversion mechanism that converts 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 responsively along the optical axis direction 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. To move. Therefore, the drive means for the focus lens structure is generally composed of a linear motor. Specifically, the linear motor is composed of a coil frame integrally combined with the focus lens structure, a yoke arranged on the lens barrel side, and magnets attached to the respective yoke pieces of the yoke. There is.

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 guide bearing portions at various places in order to firmly support the above-mentioned guide shaft. As shown in FIGS. 4 to 5, the guide bearing portion is provided with a guide shaft hole 102 having a hole diameter dimension substantially equal to the outer diameter dimension of the guide shaft. This guide shaft hole 10
2, the hollow portion 104 into which the guide shaft is fitted and supported is formed in a columnar shape that is substantially the same as the shape of the guide shaft.

Further, in this guide bearing portion 101, a taper 103 having a funnel-shaped cross section having a large hole diameter on the opening side is provided at the opening of the guide shaft hole 102 to facilitate insertion of the guide shaft. . Further, the guide bearing portion 101 is
When inserting the guide shaft, a through hole 105 for exhausting air filled in the hollow portion between the bottom surface portion of the guide shaft hole 102 and the tip end surface portion of the guide shaft is provided in the central portion of the bottom surface portion of the guide shaft hole 102. Has been.

In the guide shaft hole 102, the guide shaft is inserted into the taper 103 as it is. When the guide shaft is inserted into the guide shaft hole 102, air is filled in the hollow portion 104 between the bottom surface portion and the tip end surface portion of the guide shaft. This air is compressed by the guide shaft, passes through the through hole 105, and is exhausted to the outside of the guide bearing portion 101. As a result, the guide bearing portion 101 is
The guide shaft reaches the bottom surface of the guide shaft hole 102 to support the guide shaft.

[0009]

By the way, in order to secure the slidability of the above-mentioned focus lens structure which is moved at a relatively high speed, the lens barrel is lubricated with a relatively low viscosity such as fluorine oil. The agent is evenly applied to the entire guide shaft. Therefore, the guide shaft may be inserted into the guide shaft hole 102 in a state where the lubricant is attached to the tip end surface portion of the guide shaft, and the lubricant may be attached by closing the through hole 105 in the bottom surface portion. Therefore, the guide shaft hole 102
When the guide shaft is inserted, the internal air is not exhausted from the through hole to the outside of the guide bearing portion 101 by the lubricant. Therefore, the conventional lens barrel has a problem that the guide shaft cannot be easily inserted into the guide shaft hole 102 of the guide bearing portion 101.

In the guide shaft hole 102, the lubricant applied to the inserted guide shaft gradually accumulates between the bottom surface portion of the guide shaft hole 102 and the tip end surface portion of the guide shaft. This lubricant may pass through the through hole 105 and leak from the guide bearing portion 101 to the inside of the lens barrel, thereby contaminating the lens.

Further, the lubricant leaked from the through hole 105 into the lens barrel has a high viscosity. For example, when the lubricant collides with a stopper portion or the like, the zoom lens structure is directly joined to the stopper portion, and the zoom lens structure is However, there is a problem in that it causes a malfunction of.

Further, in the conventional lens barrel, the through hole 105 must be separately provided in the central portion of the bottom surface of the guide shaft hole 102 which constitutes the guide bearing portion 101, so that the number of assembling steps is large and it is troublesome. There were also problems.

The problem with the above-mentioned guide bearing section is that
Not only the problem peculiar to the guide bearing portion 101 that supports the guide shaft used for the movement operation of the focus lens structure of the autofocus mechanism mounted on the video camera but also the slidability of the driven body provided in other devices This is also a problem common to guide bearings that support the guide shaft to which the lubricant to be secured is applied.

Therefore, according to the present invention, the guide shaft can be easily inserted into the guide shaft hole, the number of assembling steps can be reduced, and the working efficiency can be improved. At the same time, the lubricant can be discharged to the outside of the guide bearing. This is proposed for the purpose of providing a shaft support mechanism whose accuracy is improved by preventing the shaft support mechanism.

Further, according to the present invention, the guide shaft can be easily inserted into the guide shaft hole, the number of assembling steps can be reduced, and the working efficiency can be improved. At the same time, the lubricant can flow out of the guide bearing portion. It is proposed for the purpose of providing a lens barrel in which the accuracy of the movable lens structure is improved by preventing the above.

[0016]

In the shaft support mechanism according to the present invention, which achieves the above objects, a guide shaft, which is coated with a lubricant and movably supports a driven body, and a tip end portion of the guide shaft are provided. And a guide bearing having a guide shaft hole that is inserted and supported. The guide shaft hole is formed as a regular polygonal shaft hole having a diagonal length slightly larger than the shaft diameter of the guide shaft.

The lens barrel according to the present invention, which has achieved the above-mentioned object, includes a lens barrel having an inner wall integrally formed with a guide bearing portion having a shaft hole in the optical axis direction, and a distal end portion having a guide shaft hole. A guide shaft that is inserted and supported, and on which a lubricant is applied, and a movable lens structure that is supported by the guide shaft and is moved in the optical axis direction by the lens driving means are provided. The guide shaft hole is formed as a regular polygonal shaft hole having a diagonal length slightly larger than the shaft diameter of the guide shaft.

[0018]

According to the shaft support mechanism of the present invention constructed as described above, the guide shaft is inserted into the guide shaft hole forming the guide bearing in a state where the lubricant is attached to the tip end surface of the guide shaft. . When the guide shaft is inserted into the guide shaft hole, the internal air is exhausted from the opening side of the guide shaft hole through the gap formed between the outer peripheral surface and the inner peripheral surface of the guide shaft hole. This makes it extremely easy to insert and support.

A lubricant is applied to the guide shaft in order to ensure the slidability of the driven body. When the guide shaft is inserted into the guide shaft hole, this lubricant collects in the guide shaft hole but does not leak to the outside.

According to the lens barrel of the present invention,
The guide shaft is inserted into the guide shaft hole forming the guide bearing portion in a state where the lubricant is attached to the tip end surface portion of the guide shaft. When the guide shaft is inserted into the guide shaft hole, the internal air is exhausted from the opening side of the guide shaft hole through the gap formed between the outer peripheral surface and the inner peripheral surface of the guide shaft hole. This makes it extremely easy to insert and support.

A lubricant is applied to the guide shaft in order to ensure the slidability of the driven body. When the guide shaft is inserted into the guide shaft hole, this lubricant collects in the guide shaft hole but does not leak to the outside, and therefore does not contaminate the lens or the like.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the present invention will be described in detail below with reference to the drawings. The embodiment shows a lens barrel 1 mounted on a video camera and provided with an autofocus lens mechanism for automatically focusing on a subject and an electric zoom mechanism for changing magnification. The lens barrel 1 is
As shown in FIG. 1, there is provided a lens barrel 2 formed by combining a front lens barrel 3 formed in a cylindrical shape and a rear lens barrel 4 formed in a rectangular tube shape.

As shown in FIGS. 1 to 3, the lens barrel 1 includes a zoom unit 5 and an iris unit 6 inside the barrel 2 in order from the front side of the lens barrel 1 along the optical axis.
The intermediate frame 7 and the focus unit 8 are arranged. In the following description, “front” means the left side in FIG. 1, and “rear” means the right side.

The front lens barrel 3 has a slightly larger opening diameter than the rear lens barrel 4. The front surface of the front lens barrel 3 is open, and the first fixed lens holder portion 3A is provided on the front surface facing the opening. The first fixed lens holder portion 3A is provided with a first fixed lens mounting hole 3B in this central region, and the first fixed lens group 9 is fixed in the first fixed lens mounting hole 3B. . The “fixed lens group” is one or a plurality of lens groups that are not moved in the optical axis direction at the time of shooting and are incorporated in the lens barrel. Also, the front lens barrel 3 is
Inside this, a guide shaft hole 3C for zooming is provided in the corner portions of the front surface portion facing each other.

The zoom unit 5 includes the zoom guide shaft 1
0 (10A, 10B) and these zoom guide shafts 10
A zoom lens structure 11 penetratingly supported by and movable in the optical axis direction, a zoom lens drive mechanism (not shown) located on the upper surface of the front barrel 3 to drive the zoom lens structure 11, and the zoom The first position detection sensor 12 is located below the lens driving mechanism and near the zoom guide shaft 10 to detect the position of the zoom lens structure 11.

The zoom guide shafts 10 have the same length dimension as each other, and have a length dimension sufficient to secure the amount of movement of the zoom lens structure 11. Further, a relatively viscous lubricant such as grease is applied to the zoom guide shaft 10.

The zoom lens structure 11 is composed of a zoom lens group 13 and a zoom lens holder 14 holding the zoom lens group 13, and determines the Wide end and the Tele end of the lens system of the video camera. The “movable lens group” refers to one or a plurality of lens groups that are moved in the optical axis direction in the lens barrel during shooting. The zoom lens group 13 functions as a so-called zoom lens, and is combined with the first fixed lens group 9 to adjust the angle of view.

The zoom lens holder 14 has a disk-shaped outer shape, and its outer diameter is smaller than the inner diameter of the front lens barrel 3. The zoom lens holder 14 is provided with a zoom lens mounting hole 14A in this intermediate region, and the zoom lens group 13 is fixed to this zoom lens mounting hole 14A.

Further, the zoom lens holder 14 is located on this side surface, and the zoom guide bearing portion 14 has a distance dimension which is equal to the distance between the zoom guide shafts 10.
B and 14C are provided facing each other. The zoom guide bearing portions 14B and 14C are formed at positions opposite to each other by 180 ° and penetrate through the zoom guide shaft 10 in the optical axis direction. A position detection piece 14D having a semicircular cross section is formed on the side surface of the zoom lens holder 14 along the zoom guide bearing portion 14B.

The zoom lens drive mechanism (not shown) is composed of a drive motor and a rotation-linear motion conversion mechanism attached to one side surface of the drive motor. The drive motor is
A first flexible printed cable (not shown) connected to a power supply to which a drive current is supplied is connected to the other side surface. A drive current is supplied to the drive motor to rotate it. A stepping motor is used as the drive motor. In the rotation-linear motion conversion mechanism, a driver element engaged with the zoom lens structure 11 is screwed into a rotary shaft whose outer peripheral portion is threaded. In the rotation-linear motion conversion mechanism, when the rotary shaft is rotated, the driver is moved in the optical axis direction.

The first position detecting sensor 12 receives light received across the moving region of the position detecting piece 14D integrally formed on the zoom lens holder 14 in a state where the first flexible printed cable is assembled to the front lens barrel 3. It is composed of an optical detection sensor including an element and a light emitting element.

As shown in FIG. 1, the iris unit 6 includes a base member 15 composed of a disk-shaped base portion 15A and a motor mounting portion 15B integrally projecting from a side surface portion of the base portion 15A, and the motor mounting portion. 15B and the drive motor 16 attached to it. The base portion 15A of the base member 15 has a diaphragm hole 15 whose optical axis coincides with that of each lens group.
C is formed in the center. Further, in detail, the base portion 15A is configured by stacking two thin disks, and a plurality of diaphragm blades are incorporated inside.

In the iris unit 6, the drive motor 16 is driven by the output from the control unit to drive the diaphragm blades and adjust the aperture size of the diaphragm hole 15C. The amount of light of the lens barrel 1 is adjusted by the operation of the iris unit 6. Of course, the iris unit 6 may be composed of, for example, an iris unit using an electrochromic element.

The intermediate frame 7 includes a second fixed lens group 17 and
It is composed of a second fixed lens holder 18 that holds the second fixed lens group 17. The second fixed lens holder 18 is formed in a substantially rectangular shape, and its outer dimensions are formed to be substantially the same as the outer dimensions of the rear barrel 4. The second fixed lens holder 18 is provided with a second fixed lens mounting hole 18A at the center thereof.
The second fixed lens group 17 is fixed to 8A. In addition, the second fixed lens holder 18 has a zoom guide shaft hole 18B formed in a corner portion of the rear surface portion.

The second fixed lens holder 18 is provided with focusing guide shaft holes 18C at the opposite corners of the rear surface thereof. As shown in FIGS. 2 to 3, the focusing guide shaft hole 18C is a regular octagonal shaft hole having a diagonal length slightly larger than that of a focusing guide shaft 20 described later. Composed.
Further, the focus guide shaft hole 18C is provided with a taper 18a having a funnel-shaped cross section and having a large hole diameter on the opening side at the opening.

The rear lens barrel 4 has an opening on its front surface, and a CCD solid-state image pickup device 19 is arranged on its rear surface facing the opening. Further, the rear lens barrel 4 is provided with focusing guide shaft holes 4A at the opposite corners of the inner surface of the rear surface portion. The rear lens barrel 4 is provided with a second position detection sensor mounting port (not shown) in the central region of the bottom surface. The rear lens barrel 4 is provided with a zoom guide shaft hole 4B on the side surfaces of the opposite corner portions of the opening. Further, the rear lens barrel 4 is provided with a cable lead-out portion formed in a substantially U-shape on the bottom surface side facing the zoom guide shaft hole 4B on the front surface portion.

The focus unit 8 includes a focus guide shaft 20 (20A, 20B), a focus lens drive mechanism 21 composed of constituent members housed or fixed in the rear lens barrel 4, and a focus guide shaft 20. The focus lens structure 22 is supported by and is movable in the optical axis direction, and a second position detection sensor (not shown) attached to the second position detection sensor attachment port of the rear lens barrel 4.

The focus guide shaft 20 has a length dimension sufficient to secure the amount of movement of the focus lens structure 22. Further, in order to secure the slidability of the focus lens structure 22 which is moved at a relatively high speed, a relatively low-viscosity lubricant such as fluorine-based oil is applied to the focusing guide shaft 20. Is evenly applied to the whole of the.

The focus lens drive mechanism 21 is composed of a first yoke 23A and a second yoke 24 made of metal, and magnets 25 fixed to these two yokes.

First yoke 23 and second yoke 24
Are connecting portions 23A and 24A that are screwed to the rear side surface inside the rear barrel 4, and inner yoke portions 23B and 24B that are formed to rise from one side edge of the connecting portions 23A and 24A in the optical axis direction. , The inner yoke portions 23B, 24B
The outer yoke portions 23C and 24C that are formed to rise from the other side edge of the connecting portions 23A and 24A in the optical axis direction so as to face the
And are formed in a substantially U shape.

The magnet 25 is fixed to the inner surfaces of the first yoke 23A and the second yoke 24 facing the inner yoke portions 23B and 24B of the outer yoke portions 23C and 24C, respectively, by an adhesive or the like. The magnets 25 are magnetized so that the magnetic poles are different in the directions from the outer yoke portions 23C and 24C toward the inner yoke portions 23B and 24B, respectively.
A closed magnetic circuit is formed between C and the inner yoke portions 23B and 24B.

The focus lens structure 22 includes a focus lens group 26, a focus lens holder 27 for holding the focus lens group 26, a coil bobbin 28 formed integrally with the focus lens holder 27,
The coil is wound around the coil bobbin 28, and the second flexible printed cable is connected to both ends of the coil. Focus lens group 26
Functions as a focus lens and performs focus adjustment in combination with the second fixed lens group 17.

The focus lens holder 27 has a rectangular outer shape, and its outer dimension is smaller than the inner dimension of the rear lens barrel 4. The focus lens holder 27 is
A focus lens mounting hole 27A is provided in this intermediate region, and the focus lens group 26 is fixed in this focus lens mounting hole 27A.

In the focus lens holder 27, when the focus lens structure 22 is combined with the focus lens driving mechanism 21, a penetrating space portion 27B is provided at a position corresponding to the tip of the inner yoke portions 23B and 24B of the yokes 23 and 24. It is provided. The penetrating space portion 27B has an opening dimension slightly larger than the thickness dimension of the tips of the inner yoke portions 23B and 24B, and the focus lens structure 22 is supported by the focusing guide shaft 20 to move in the optical axis direction. At this time, the tip portions of the inner yoke portions 23B and 24B of the focus lens drive mechanism 21 can be penetrated. A coil bobbin 28 is integrally provided on the rear surface side of the focus lens holder 27, and a coil is wound around the outer peripheral portion of the coil bobbin 28.

The focus lens holder 27 is located on the side surface of the coil bobbin 28, and the focus guide bearing portions 27C and 27D having a distance equal to the distance between the focus guide shaft 20 and the focus guide shaft 20 face each other. It is provided. Focus guide bearings 27C, 27D
Are formed at positions opposite to each other by 180 °, and the focusing guide shafts 20 are respectively penetrated therethrough.

Further, the focus lens holder 27 includes
In a state where the focus lens structure 22 is incorporated in the rear lens barrel 4, the terminal connecting portion 3 is located on the side surface portion facing the rear surface portion of the rear lens barrel 4 and the bottom surface portion of the coil bobbin 28.
1 is provided. Both ends of the coil are drawn out to the terminal connecting portion 31.

Further, in the focus lens holder 27, the focus lens structure 22 is incorporated in the rear lens barrel 4 at a position facing a second position detecting sensor mounting opening (not shown) provided in the rear lens barrel 4. A magnet holder is provided, and a position detecting magnet is attached to the magnet holder.

The second flexible printed cable is
A connection plate at one end is attached to the terminal connection portion 31 of the focus lens structure 22, and both ends of the coil are soldered to this connection plate. The second flexible printed cable is provided with a support hole penetratingly supported at the tip end portion of the focusing guide shaft 20, and a support portion supported by the cable pull-out portion of the rear lens barrel 4. The other end of the second flexible printed cable is connected to a power source (not shown).

The second position detection sensor (not shown) is attached to the second position detection sensor mounting port provided in the central region of the bottom surface of the rear lens barrel 4. The resistance value of the second position detection sensor changes due to the change in the magnetic flux density by the position detection magnet attached to the focus lens holder 27 of the focus lens structure 22, and the change amount is counted and the optical axis of the focus lens structure 22 is counted. Detect the direction position.

A method of assembling the lens barrel 1 of the embodiment having the above structure will be described below. The lens barrel 1 is
The focusing guide shafts 20 are inserted into the focusing guide shaft holes 4A of the rear lens barrel 4 and supported in a cantilevered state. Further, inside the rear lens barrel 4, a first yoke 23 and a second yoke 24 of the focus lens drive mechanism 21 are arranged in parallel to each other in parallel with the focusing guide shaft 20, and the rear lens barrel 4 of the rear lens barrel 4 is provided. It is fixed to the inner rear surface with screws.

On the focusing guide shaft 20, the focusing guide bearing portion 27C of the focusing lens structure 22 is provided.
The focus lens structure 22 is supported so as to be movable in the optical axis direction by penetrating 27D. At this time, the focus lens structure 22 is combined with the first yoke 23A and the second yoke 24 of the focus lens drive mechanism 21 fixed inside the rear barrel 4. The focus lens structure 22 is combined with the focus lens drive mechanism 21, and the inner yoke portions 23B and 24B of the first yoke 23A and the second yoke 24 are penetrated through the penetrating space portion 27B.

Terminal connection portion 3 of the focus lens structure 22
The second flexible printed cable connected to No. 1 has a support hole penetratingly supported in the tip portion of the focusing guide shaft 20 supported by the rear lens barrel 4 in a cantilever state while being greatly curved, The support portion is supported by the cable pull-out portion provided on the rear lens barrel 4.

The focusing guide shaft 20 is applied to the taper 18a of the focusing guide shaft hole 18C provided on the rear surface portion of the intermediate frame 7 at the tip end portion in a state where the lubricant is attached to the tip end surface portion. It can be easily fitted as it is.
When the focusing guide shaft 20 is inserted into the focusing guide shaft hole 18C, air is filled in the hollow portion between the bottom surface portion of the focusing guide shaft hole 18C and the tip end surface portion of the focusing guide shaft 20. . This air is compressed by the focusing guide shaft 20, and the outer surface of the focusing guide shaft 20 and the focusing guide shaft hole 18C.
The gas is exhausted from the opening side of the focusing guide shaft hole 18C through a gap generated between the inner surface of the focusing guide shaft hole 18C and the inner surface of the focusing guide shaft.

When the focusing guide shaft 20 is further inserted into the focusing guide shaft hole 18C, the lubricant adhered to the tip end surface portion of the focusing guide shaft 20 is removed.
The space is filled between the bottom surface portion of the focusing guide shaft hole 18C and the tip end surface portion of the focusing guide shaft 20. The lubricant is compressed by the focusing guide shaft 20 and is filled in the gap formed between the inner surface of the focusing guide shaft hole 18C and the outer surface of the focusing guide shaft 20.
The focus guide shaft 20 is inserted into the focus guide shaft hole 18C until the bottom face portion is reached.
As a result, the guide bearing portion supports the focusing guide shaft 20 when the focusing guide shaft 20 reaches the bottom surface of the focusing guide shaft hole 18C.

The side surface of the intermediate frame 7 is fitted to the inner edge of the front surface of the rear lens barrel 4. The intermediate frame 7 has a base portion 15A of the base member 15 that constitutes the iris unit 6 on the front surface portion.
Is fitted. At this time, in the iris unit 6, the drive motor 16 is located above the rear lens barrel 4, and the motor mounting portion 15B of the base member 15 is screwed to the outer edge portion of the front surface portion of the rear lens barrel 4.

The rear lens barrel 4 is supported in a cantilever state by inserting the zoom guide shafts 10 into the zoom guide shaft holes 4B. On the zoom guide shaft 10,
The zoom guide bearing portion 14B of the zoom lens structure 11,
By penetrating 14C, the zoom lens structure 11 is supported so as to be movable in the optical axis direction.

The zoom guide shaft 10 has a zoom guide shaft hole 3C formed in the front surface of the front barrel 3 at its tip. At this time, the front lens barrel 3 is screwed to the inner edge of the opening on the front surface side of the rear lens barrel 4. Finally, the front lens barrel 3 and the rear lens barrel 4 are screwed to the upper portion of a zoom lens drive mechanism (not shown),
The lens barrel 1 is assembled.

Lens barrel 1 assembled as described above
In the zoom unit 5, when a drive current is supplied from a power source (not shown) to a drive motor that constitutes a zoom lens drive mechanism, the drive motor is rotationally driven. When this drive motor is rotated, it rotates the rotation shaft of the rotation-linear motion conversion mechanism that constitutes the zoom lens drive mechanism. When the rotating shaft is rotated, the driving element assembled to the rotating shaft is moved in the optical axis direction. The driver is moved in the optical axis direction while being engaged with the zoom lens structure 11.

Therefore, the zoom lens structure 11 is supported by the zoom guide shaft 10 and moved in the optical axis direction by the zoom lens drive mechanism, as indicated by the arrow M in FIG. As a result, the zoom lens group 13 constituting the zoom lens structure 11 adjusts the distance between the zoom lens group 13 and the first fixed lens group 9 provided in the front lens barrel 3, and zoom control is performed.

In the zoom lens structure 11, the position detecting piece 14D passes between the light receiving element and the light emitting element of the first position detecting sensor 12 when the central portion of the front lens barrel 3 is moved. The first position detection sensor 12 detects that the cutoff state between these elements has been released and sends a detection output to the control unit. The rotation operation of the stepping motor is controlled by the output of the position detection sensor 12.

In the focus unit 8, the coil 29 integrated with the focus lens structure 22 forms the outer yoke portions 23C, 24C-magnet 25-inner yoke formed by the magnetic flux emitted from the magnet 25 constituting the focus lens driving mechanism 21. Part 23B, 24B-connecting part 23A, 2
4A—Closes the closed magnetic path that passes through the outer yoke portions 23C and 24C. When a drive current is supplied from a power source (not shown), the coil 29 generates a magnetic flux in a direction corresponding to the direction of the drive current to act on the closed magnetic circuit.

Therefore, the focus lens structure 22
2 is supported by the focusing guide shaft 20 in the direction of the optical axis by the magnetic thrust corresponding to the direction of the drive current supplied between the coil and the closed magnetic circuit, as indicated by the arrow N in FIG. Move works. At this time, the focus lens structure 22 moves while the slidability is secured by the lubricant applied to the focus guide shaft 20. As a result, the focus lens group 26 forming the focus lens structure 22 is adjusted in the distance between the focus lens group 26 and the CCD solid-state image pickup device 19 arranged in the rear barrel 4 to perform focus control. An image that has passed through the focus lens group 26 is picked up on 19.

Further, as the focus lens structure 22 is supported by the focus guide shaft 20 and moves in the axial direction, the position detection magnet attached to the focus lens holder 27 causes the position detection magnet to move to the second position of the rear lens barrel 4. By facing the second position detection sensor attached to the position detection sensor mounting port, the magnetic flux density exerted on the second position detection sensor is changed. The second position detection sensor detects the position of the focus lens structure 22 in the optical axis direction by counting the amount of change in the resistance value due to the change in the magnetic flux density.

Therefore, in the focus unit 8,
Based on the detected position of the focus lens structure 22, power required for the coil of the focus lens drive mechanism 21 is turned on to control the movement operation of the focus lens structure 22, and the focus lens group attached to the focus lens holder 27. 26 focus control is performed.

In the example lens barrel 1 described above,
Since a relatively low-viscosity lubricant such as fluorine-based oil is evenly applied to the entire focus guide shaft 20 that supports the focus lens structure 22, slidability of the focus lens structure 22 is ensured, and the focus lens structure 22 is focused. The lens structure 22 can be moved at a relatively high speed.

Further, in the lens barrel 1, the second fixed lens holder 18 constituting the intermediate frame 7 is provided with the focusing guide shaft hole 18C, and the focusing guide shaft hole 1
Since the hollow portion 18b of 8C has a regular octagonal cross section, the hollow portion 1 between the bottom surface portion of the focusing guide shaft hole 18C and the tip end surface portion of the focusing guide shaft 20 is formed.
Since the air filling 8b is easily exhausted, the focusing guide shaft hole 18C of the second fixed lens holder 18 is provided.
The focusing guide shaft 20 can be easily inserted into the.

Further, in the lens barrel 1, since the hollow portion 18b of the focusing guide shaft hole 18C is provided in a regular octagonal cross section, the focusing guide shaft hole 18C is formed.
The lubricant filled between the bottom surface of the focusing guide shaft 20 and the bottom surface of the focusing guide shaft 20 is compressed by the focusing guide shaft 20 so as to be between the inner surface of the focusing guide shaft hole 18C and the outer surface of the focusing guide shaft 20. Since the gap is filled in, the lubricant is prevented from flowing out of the second fixed lens holder 18.

Further, in the lens barrel 1, since the hollow portion 18b of the focusing guide shaft hole 18C is provided in a regular octagonal cross section, the focusing guide shaft hole 1 is formed.
Since it is not necessary to separately provide a through hole in the central portion of the bottom surface of 8C, the number of assembling steps can be reduced and the correction of the die machining can be facilitated.

Further, in the lens barrel 1, the taper 18a is provided at the opening of the focusing guide shaft hole 18C, so that the focusing guide shaft 20 can be easily inserted.

Further, in the above-described embodiment, the focusing guide shaft hole 18C of the second fixed lens holder 18 constituting the intermediate frame 7 is provided in a regular octagonal shape in cross section. It may be provided in a polygonal column such as a prism.

In the above-mentioned embodiment, the example applied to the lens barrel of the video camera is shown.
It can be applied to all devices including a guide bearing that supports a guide shaft to which a lubricant for ensuring slidability of a driven body other than a lens is applied.

[0072]

As described in detail above, according to the shaft support mechanism of the present invention, the hollow portion of the guide shaft hole forming the guide bearing is provided in the shape of a polygonal column, so that the number of assembling steps can be reduced. The work efficiency can be improved by facilitating the assembly, and the performance can be improved by preventing the lubricant from flowing out of the guide bearing.

According to the lens barrel of the present invention,
Since the hollow portion of the guide shaft hole that constitutes the guide bearing portion is provided in a polygonal column shape, the work efficiency can be improved by reducing the number of assembly steps and facilitating the assembly, and the lubricant can be transferred to the outside of the guide bearing. The performance is improved by preventing the outflow of water.

[Brief description of drawings]

FIG. 1 is a sectional side view of a main part of a lens barrel mounted in a video camera shown as an embodiment of the present invention.

FIG. 2 is a front view showing a focus guide bearing hole of a second fixed lens holder that constitutes an intermediate frame provided inside the lens barrel.

FIG. 3 is a vertical cross-sectional view showing a focus guide bearing hole of a second fixed lens holder that constitutes an intermediate frame provided inside the lens barrel.

FIG. 4 is a front view showing a guide bearing hole forming a guide bearing portion provided inside a conventional lens barrel.

FIG. 5 is a vertical cross-sectional view showing a guide bearing hole of a guide bearing portion provided inside a conventional lens barrel.

[Explanation of symbols]

 1 Lens barrel 2 Lens barrel 3 Front lens barrel 4 Rear lens barrel 5 Zoom unit 6 Iris unit 7 Intermediate frame 8 Focus unit 11 Zoom lens structure (movable lens structure) 18 Second fixed lens holder 18C Focus guide shaft hole 18a Focusing guide shaft hole taper 18b Focusing guide shaft hole hollow portion 20 Focusing guide shaft 21 Focus lens driving mechanism (lens driving means) 22 Focus lens structure (movable lens structure)

Claims (4)

[Claims] 1. A guide shaft comprising a guide shaft to which a lubricant is applied to movably support a driven body, and a guide bearing having a guide shaft hole into which a tip end portion of the guide shaft is inserted and supported. The shaft support mechanism is characterized in that the shaft hole is formed as a regular polygonal shaft hole having a diagonal length slightly larger than the shaft diameter of the guide shaft. 2. The shaft support mechanism according to claim 1, wherein the opening of the guide shaft hole is provided with a funnel-shaped chamfer for invoking. 3. A lens barrel having an inner wall integrally formed with a guide bearing portion having a shaft hole in the optical axis direction, and a guide shaft having a tip end inserted into the guide shaft hole for support and a lubricant applied. And a movable lens structure that is supported by the guide shaft and is moved in the optical axis direction by the lens driving means.The guide shaft hole has a diagonal length slightly larger than the diameter of the guide shaft. A lens barrel characterized by being configured as a regular polygonal shaft hole. 4. The lens barrel according to claim 3, wherein the opening of the guide shaft hole is provided with a funnel-shaped chamfer for inviting.