JPH0634865A - Lens barrel - Google Patents

Abstract

PURPOSE:To provide a lens barrel where a driving means is not arranged on the outer periphery side of an outside helicoid frame so that a camera is miniaturized as for a double helcoid type lens barrel. CONSTITUTION:The lens barrel in which focusing is performed or a focal distance is changed by moving a photographing optical system backward and forward in an optical axis direction is provided with a double helicoid frame for moving the photographing optical system backward and forward in the optical axis 01 direction, an internal gear 2c provided on the inner periphery of the outside helicoid frame 2 of the double helicoid frame, and a driving gear 10 meshing with the internal gear 2c and transmitting driving force from a driving source to the outside helicoid frame 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens barrel, more specifically, in a still camera or a video camera, a double helicoid frame is used to move a photographing optical system back and forth in the optical axis direction for focusing. Alternatively, the present invention relates to a lens barrel for switching the focal length between tele and wide, and changing the focal length such as zooming.

[0002]

2. Description of the Related Art It has been known for a long time that a double helicoid frame is used to extend and retract an optical system such as a photographing lens. For example, Japanese Patent Application Laid-Open No. 57-66410 discloses a technical means for manually driving a double helicoid frame for focusing, and Japanese Patent Application Laid-Open No. 2-22004.
The publication discloses a technical means for zooming with a double helicoid frame. And Japanese Patent Application No. 4-17
No. 77 discloses a double helicoid type zoom drive mechanism using an inner cam and a float key.

[0003]

However, the conventional technical means using the double helicoid frame has the following problems. That is, the means disclosed in the above-mentioned JP-A-57-66410 provides a distance ring on the outer peripheral side of the outer helicoid frame, and manually rotates the distance ring to drive the helicoid frame to move the optical system. Therefore, the entire lens barrel becomes bulky and it is difficult to reduce the size, and the Japanese Patent Application No. 4-1777 has a rotary ring provided outside the fixed frame to rotate it. As a result, since zoom driving is performed, the size inevitably increases in the radial direction, making it difficult to miniaturize the camera.

An object of the present invention is to provide a lens barrel which can reduce the size of a camera without disposing drive means on the outer peripheral side of the outer helicoid frame in order to eliminate such a conventional problem. There is.

[0005]

A lens barrel according to the present invention is a lens barrel for advancing and retracting an image-taking optical system in the optical axis direction for focusing or changing a focal length. Double helicoid frame that advances and retracts in the direction, and an internal gear that is provided on the inner circumference of the outer helicoid frame of the double helicoid frame, and drives to the outer helicoid frame by meshing with this internal gear And a drive gear for transmitting the driving force from the source.

[0006]

[Operation] The driving force is transmitted to the drive gear meshing with the internal gear, the outer helicoid frame is rotated, and the inner helicoid frame meshing with the outer gear is advanced and retracted in the optical axis direction to be held in the same frame. Move the taking optical system. Further, the rotation restricting member attached to the inner helicoid frame is fitted into the straight guide groove of the fixed frame, whereby the inner helicoid frame is moved straight.

[0007]

The present invention will be described below with reference to the illustrated embodiments. 1 to 7 show an embodiment of the lens barrel of the present invention. In this embodiment, the lens barrel of the present invention is applied to a bifocal switching type camera. 1 and 2 are exploded perspective views of the lens barrel of the present embodiment. This lens barrel is screwed into the outer helicoid frame 2 and the same frame 2 which are screwed into the fixed frame 1a. A double helicoid frame composed of the inner helicoid frame 3 and a photographing optical system composed of the first lens group L1 and the second lens group L2 mounted in the inner helicoid frame 3, and also mounted in the inner helicoid frame 3. Shutter sector blade 12 and
The drive mechanism arranged in the double helicoid frame and the linear guide mechanism for the inner helicoid frame 3 constitute the main part.

In this two-focal-switching type camera, the first lens is used when the taking lens is at the sinking position and the wide position.
Only the lens unit L1 is located on the optical axis of the taking lens, and at the tele position, the first lens unit L1 and the second lens unit L2.
Is located on the optical axis of the taking lens.

The fixed frame 1a is composed of a cylindrical body integrally formed in the central portion of the fixed frame plate 1 which is integrally attached to the immovable main body 15, and a female helicoid screw 1b is engraved on the inner surface thereof. Has been done. The main body 15 has a horizontally long rectangular front shape and constitutes a first fixed frame member having a channel-shaped horizontal cross-sectional shape, and an exposure opening 15b is provided on the back wall thereof. ing. Further, a protrusion 15a for holding a rear end of a support shaft of the drive gear 10, which will be described later, is formed at a lower edge portion of the opening 15b.

The fixed frame plate 1 is integrally fixed to the main body 15 thus formed by the screws 16 (see FIG. 3). Then, the fixed frame 1 of the fixed frame plate 1
The outer helicoid frame 2 is screwed into the inside of a. The outer helicoid frame 2 is composed of a cylindrical body in which a male helicoid screw 2a to be screwed into the female helicoid screw 1b is engraved at the rear end portion of the outer peripheral surface, and the inner helicoid frame 2 is rotated with the same. Female helicoid screws 2b having opposite directions are engraved. An internal gear 2c for driving the helicoid frame is formed on the rear end of the inner peripheral surface of the helicoid frame 2.

A drive gear 10 meshes with the internal gear 2c. The drive gear 10 is composed of a long gear extending along the direction of the central axis 02 of the helicoid frame 2, and the support shaft 10a projecting forward thereof has a second gear described below.
The support shaft 10b rotatably held by the fixed frame member 9 and protruding rearward is rotatably held by the protruding portion 15a. A driving force is transmitted to the drive gear 10 from a motor (not shown) via a reduction gear train.

The second fixed frame member 9 is formed of a block body which is longer than the drive gear 10 in the direction of the central axis 02 and is slightly flat, and the lower half thereof rotates substantially the upper half of the drive gear 10. A recess 9a is provided to store it freely. The second fixed frame member 9 penetrates through the partition wall in the inner helicoid frame 3 described below, and the rear end portion thereof has the rear end portion of the projecting portion 1.
A cam 9c fixed to 5a, for swinging a second lens group holding frame 6 to be described later is provided at a corner portion outside the front end thereof.
Are formed. The second group lens holding frame 6 and the frame support member 7 are provided at the front end opposite to the cam 9c.
Is formed with a stopper 9b for restricting the forward movement thereof, and a protrusion 9d with which the rotation restricting member 8 is engaged is formed on the lower portion of the front surface.

The inner helicoid frame 3 has a female helicoid screw 2 of the outer helicoid frame 2 at the rear end portion of its outer peripheral surface.
It is composed of a cylindrical body engraved with a male helicoid screw 3a screwed into b, and the partition wall 3d is provided in the middle of the inner peripheral surface thereof.
Is formed, and the inside of the helicoid frame is divided into a first half and a second half. In this partition wall 3d, a circular opening 3e is formed above the center axis 02 of the helicoid frame so as to face the photographing lens, and the disk shape is held so that the first lens unit L1 faces the opening 3e. The first group lens holding frame 4 is fitted to the front end surface of the helicoid frame 3. Therefore, in this lens barrel, the photographing lens optical axis 01 is parallel to the upper side of the central axis 02 of the helicoid frame, and the two do not match.

Further, the circular opening 3e of the partition 3d.
A through hole 3f through which the second fixed frame member 9 is inserted is formed in the lower part of the. A fixed base 3b is integrally projectingly provided in the lower part of the front surface side of the partition wall 3d near the through hole 3f, and the rotation restricting member 8 is attached to the fixed base 3b. The rotation restricting member 8 is formed by bending a short piece of an L-shaped thin elongated plate member upward at a right angle, and the bent piece 8b is integrally attached to the fixed base 3b with a screw or the like. At the same time, by inserting the long piece 8a into the through hole 3f, the bent piece 8b of the rotation restricting member 8 engages with the protruding portion 9d on the front surface of the second fixed frame member 9 and the long piece 8a. Fits into the bottom of the fixed frame member 9 to regulate the rotation of the helicoid frame 3. The rotation restricting member 8 moves back and forth together with the inner helicoid frame 3, and slides on the bottom surface of the second fixed frame member 9.

Further, a support shaft 3c is fixed to the front of the partition wall 3d in the vicinity of the fixed base 3b, and the base 11a of the sector arm 11 is rotatable on the support shaft 3c. Is fitted to. The tip of this arm 11 extends above the through hole 3f, and the drive pin 11b fixed rearward at the end of the arm 11 passes through the long hole 3g formed in the partition wall 3d. It extends behind the partition wall 3d.

The drive pin 11b serves to open and close a pair of sector blades 12 for sector shutters (only one is shown in FIG. 2) arranged along the rear surface of the partition wall 3d. is there. The pair of sector blades 12 are rotatably attached to the rear surfaces of the partition walls 3d at their bases by supporting shafts, and are rotated in opposite directions by the drive pins 11b, so that the circular openings 3e are formed. Open and close. Further, on the back surface side of the pair of sector blades 12, a blade pressing member 5 for pressing the sector blades is arranged. The blade pressing member 5 is formed in a shape in which the lower part of the disk is cut out by about 1/3, and a circular opening 5b having the same shape is formed in a portion corresponding to the circular opening 3e, and a long hole 3g and a support shaft are formed. A long hole 5c and a shaft hole are provided at corresponding positions.

On the rear surface of the partition wall 3d of the inner helicoid frame 3, a support shaft 3h for holding the second group lens holding frame 6 and the frame supporting member 7 is fixed so as to extend rearward. There is. The fork portions 7b, 7c and 2 provided at the front and rear ends of the frame support member 7 are attached to the support shaft 3h.
Through holes formed respectively in the base 6a of the group lens holding frame 6 are inserted, and both are movably held. For this holding, the base 6a of the second group lens holding frame 6 is inserted into the support shaft 3h so that the forks 7b and 7c hold it.

The second group lens holding frame 6 has the base portion 6a.
Is formed of a relatively thick cylindrical body, and the base 6
A lens frame 6c supporting the second lens group L2 is integrally formed at the tip of an arm 6b extending from a. In addition, a spring hooking pin 6e is projectingly provided on the front surface of the arm 6b, and a projecting piece is formed on the upper surface of the lens frame 6c, and a hemispherical sliding contact portion is formed on the front surface of the projecting piece. 6d is provided. The sliding contact portion 6d slides on the back surface of the blade pressing member 5 when the second lens group holding frame 6 rotates to move the second lens group L2 in and out of the photographing optical axis 01.
It serves to guide the second lens unit L2 to move in the same plane.

The second group lens holding frame 6 is rotated clockwise about the support shaft 3h by the elastic force of the elastic coil spring 14 hung over the pin 6e and the blade pressing member 5. Although the turning habit (as viewed from the front side shown in FIG. 6) is imparted, when the lens barrel sinks and when the wide-angle shooting is performed, the restriction pin fixed to the base portion 6a outward in the radial direction is fixed. 6f abuts on the outer surface of the second fixed frame member 9 on which the cam 9c is formed to regulate the rotational habit, and the second group lens holding frame 6 is positioned below the circular opening 3e so that the photographing optical axis. 01 has been evacuated. Then, at the time of telephoto shooting, the restriction pin 6f contacts the cam 9c of the second fixed frame member 9, and the elastic force of the coil spring 14 causes the second group lens holding frame 6 to rotate clockwise around the support shaft 3h. The second lens group L2 is rotated to be inserted into the photographing optical axis 01. At this time, the back surface of the blade pressing member 5 is adjusted so that the center of the second lens group L2 coincides with the photographing optical axis 01. Is provided with a stopper pin 5a with which the second group lens holding frame 6 abuts. On the other hand, a guide pin 7d, which also serves as a spring, is provided at the tip of the fork portion 7b on the front side of the frame support member 7, and is spanned between the pin 7d and the partition wall 3d of the inner helicoid frame 3. The elastic force of the elastic coil spring 13 imparts the habit of moving the frame support member 7 forward. Since the frame support member 7 is provided with the habit of moving to the front in this way, the frame support member 7 is sandwiched between the fork portions 7b and 7c.
The group lens holding frame 6 also moves forward, whereby the sliding contact portion 6d of the second group lens holding frame 6 is moved to the blade pressing member 5.
Abut the back side of. The guide pin 7d is fitted in two guide ribs 17a and 17b (see FIGS. 3 and 7) integrally formed on the inner surface of the peripheral wall of the inner helicoid frame 3 so as to project inward. , The guide ribs 17a, 17
While being guided in the optical axis direction by b, the rotation of the frame support member 7 is restricted.

A claw-shaped locking arm 7a extends from the rear portion of the frame supporting member 7, and the locking arm 7a is provided at the front portion of the second fixed frame member 9 during telephoto shooting. The second group lens holding frame 6 is engaged with the stopper 9b
And the frame support member 7 is restricted so as not to move further forward. However, since the inner helicoid frame 3 moves further forward, it is separated from the sliding contact portion 6d that is in contact with the back surface of the blade pressing member 5. Then, by this, the inter-group distance between the first lens unit L1 and the second lens unit L2 is obtained. When the inner helicoid frame 3 further moves forward, only the first lens unit L1 comes out to the front, and the focusing operation at the time of telephoto shooting is performed.

Next, a description will be given of the bifocal switching operation of the lens barrel of the above embodiment having the above-mentioned structure.
FIG. 3 shows a state of the lens barrel when the lens barrel is retracted. In this state, the rotational force is transmitted to the drive gear 10 through the drive motor and the reduction gear train (not shown), and when the drive gear 10 rotates, the outer helicoid frame 2 receives the male helicoid screw 2a and the female helicoid screw 2a. 1b
Is rotated forward around the central axis 02 of the helicoid frame while rotating counterclockwise. At the same time, the female helicoid screw 2b and the male helicoid screw 3a cause the inner helicoid frame 3 whose rotation is restricted by the rotation restricting member 8 to move straight forward.

Then, the wide photographing state shown in FIG. 4 is reached. At this wide time, since the restriction pin 6f of the second group lens holding frame 6 is in contact with the outer surface of the second fixed frame member 9 on which the cam 9c is formed, the second group lens holding frame 6 resists its own habit. And is rotated and is positioned below the circular opening 3e and retracted from the photographing optical axis 01. The focusing operation in the wide-angle shooting state is performed by further moving the entire first lens unit L1 forward from the infinite state as shown by the chain line. Even in this focusing operation area, the second group lens holding frame 6 remains retracted from the photographing optical axis 01. If the sector shutter is operated in this state, wide-angle shooting is performed.

Next, to set the camera to the telephoto shooting state,
The drive gear 10 may be further rotated from the wide-angle shooting state. When the drive gear 10 is rotated, the outer helicoid frame 2 and the inner helicoid frame 3 are further extended forward by the helicoid screw, and the second lens unit L2 gradually enters the photographing optical axis 01.

That is, when the inner helicoid frame 3 is extended, the second group lens holding frame 6 which moves together with the inner helicoid frame 3 is moved.
The restriction pin 6f is released from the restriction by the cam 9c of the second fixed frame member 9, and is separated from the cam 9c. And
When the telephoto shooting reaches an infinite state, as shown in FIG. 5, the second group lens holding frame 6 rotates by its own habit, and its projecting piece comes into contact with the stopper pin 5a and stops. The second lens unit L2 enters the photographing optical axis 01, and switches the optical system to the focal point during telephoto. At this time, the locking arm 7a of the frame support member 7 is engaged with the stopper 9b provided at the front part of the second fixed frame member 9, and the second group lens holding frame 6 and the frame support member 7 are Restrict it so that it will not move further forward. Then, the inner helicoid frame 3 further moves toward the front, and the inter-group distance between the first lens unit L1 and the second lens unit L2 is provided and then stopped. At this time, the sliding contact portion 6d that was in contact with the back surface of the blade pressing member 5 is separated.

The focusing operation at the time of tele is performed by further extending the inner helicoid frame 3. At this time, since the second lens unit L2 cannot move forward, only the first lens unit L1 is extended as indicated by the chain line.

If the sector shutter is operated in this state, shooting in the tele state is performed. The shutter operation is performed by the drive pin 11 of the sector arm 11 by a drive source (not shown).
By swinging b, the pair of sector blades 12 are rotated in opposite directions, and the circular opening 3e is opened and closed.

When the lens barrel moves back from the telephoto shooting position to the retracted position via the wide shooting position, the rotation of the drive gear 10 is reversed, and the outer helicoid frame 2 is rotated clockwise while being retracted. To do. Then, the inner helicoid frame 3 is also retracted, and the second group lens holding frame 6 is retracted to the outside of the optical axis while the coil spring 14 is charged by the cam 9c of the second fixed frame member 9, and the outer helicoid frame 2 and the inner helicoid frame 3 are held. Are polymerized in the fixed frame 1a and are housed as shown in FIG.

Further, in the above embodiment, the internal gear 2c is provided at the rear portion of the inner peripheral surface of the outer helicoid frame 2, and the drive gear 10 is meshed with the internal gear 2c for driving.
This is achieved by other means, for example, the fixed frame 21
A gear 22a may be provided on the rear portion of the outer peripheral surface of the outer helicoid frame 22 that is screwed into the inner helicoid screw, the timing belt 20 may be meshed with the gear 22a, and the timing belt 20 may be driven by the drive gear 10. The ultrasonic motor may be used as an actuator for direct drive.

In the above embodiment, the case where the present invention is applied to the lens barrel of the bifocal switching type camera is explained. This is a lens mirror using a single focus double helicoid without the second lens group. It may be a cylinder or a lens barrel using a double helicoid of a zoom camera.

[0030]

As described above, according to the present invention, the internal gear is provided on the inner peripheral surface of the outer helicoid frame, and the drive gear meshing with the internal gear is arranged on the inner peripheral side of the inner helicoid frame. Since the drive gear is driven to perform the double feeding, the size in the radial direction becomes smaller than that of the conventional type, which contributes to downsizing of the camera. In addition, the structure is simple and the number of parts is reduced, so the cost is also reduced.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a rear side of a lens barrel showing an embodiment of the present invention.

FIG. 2 is an exploded perspective view of a front side of a lens barrel showing an embodiment of the present invention.

FIG. 3 is an enlarged cross-sectional view of an essential part showing a sinking state of the lens barrel of the embodiment.

FIG. 4 is an enlarged main-part sectional view showing a wide state of the lens barrel of the embodiment.

FIG. 5 is an enlarged main-part sectional view showing a telephoto state of the lens barrel of the embodiment.

FIG. 6 is an enlarged front view of the lens barrel of the above embodiment with the first group lens holding frame removed.

FIG. 7 is an enlarged rear view of the lens barrel of the above embodiment.

FIG. 8 is a sectional view of an essential part showing another example of the driving force transmission means.

[Explanation of symbols]

 01 ………… Shooting lens optical axis (optical system optical axis) 1a ………… Fixed frame 2 ……………… Outside helicoid frame (double helicoid frame) 3 ……………… Inside helicoid frame (double helicoid frame) ) 2c ………… Internal gear 10 ………… Drive gear

Claims (1)

[Claims] 1. A double lens helicoid frame for advancing / retreating the photographing optical system in the optical axis direction in a lens barrel for focusing or changing the focal length by advancing / retreating the photographing optical system in the optical axis direction, Of the double helicoid frame, an internal gear provided on the inner circumference of the outer helicoid frame, and a drive gear that meshes with the internal gear and transmits the driving force from the drive source to the outer helicoid frame, A lens barrel comprising: