JPH0869041A - Lens barrel - Google Patents

Abstract

PURPOSE: To provide a lens barrel reduced in cost and saving space corresponding to a photographic lens, without need for manufacturing a rotary barrel corresponding to each photographic lens. CONSTITUTION: A collapsed position cam surface and an extended position cam surface are formed in such a manner that the angle on a prescribed circumference is set constant and only the lead angles of helicoid screws 6a and 7a are changed for the lens barrel constituted so that the distance between the collapsed and extended positions is different. Even if the extent of the movement from the collapsed position to the extended position of a movable barrel 6 is different, the angle of the rotation of the rotary barrel 7 is set constant and only the lead angles of the helicoid screws 6a and 7a are changed to form the collapsed and extended position cam surfaces, so that it is unnecessary that the position of a position detecting device actuated by a cam 7f on the outer periphery of the rotary barrel 7 is changed. Since only the lead angles can be made to correspond to each photographic lens, for working, parts for other lens barrel can be used in common.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens barrel of a camera.

[0002]

2. Description of the Related Art Conventionally, with a helicoid screw for advancing and retracting a photographing lens in the optical axis direction, a cam is formed on the outer circumference of a rotary cylinder for detecting the position of the photographing lens in the optical axis direction, and the leaf is formed by the cam. The position in the optical axis direction was detected by turning on and off switches and the like.

[0003]

However, there are various problems in taking lenses having different lens characteristics. For example, in shooting lenses with different focal lengths as the lens characteristics, the amount of movement of the movable barrel in the optical axis direction from the retracted position to the extended position is different, and if the helicoid screw is formed with the same lead angle, the rotation angle of the rotating barrel changes. Will end up. Therefore, it is necessary to shift the positions of the switches and the like that are operated by the position detection cams formed on the outer periphery of the rotary cylinder. Further, if a plurality of mounting positions of the above-mentioned switches are prepared according to the focal length of the taking lens, a wide mounting space is required, which is an obstacle to downsizing of the camera.

Further, if a rotary cylinder corresponding to each photographing lens is made, the above problems can be solved, but the cost will increase. Therefore, it is an object of the present invention to provide a space-saving, low-cost lens barrel that accommodates taking lenses having different characteristics.

[0005]

To achieve the above object, the present invention is directed to a rotary cylinder having a female helicoid screw, a movable cylinder holding a taking lens and having a male helicoid screw, and restricting rotation of the movable cylinder. In the lens barrel which is composed of a straight guide and which moves the movable barrel forward and backward in the optical axis direction by the rotation of the rotary barrel, the movable barrel can move forward and backward between a retracted position in a non-photographing state and a retracted position in a photographing state. , The rotary cylinder has a retracted position cam surface for detecting that the movable cylinder is in the retracted position and a retracted position cam surface for detecting that the movable cylinder is in the retracted position, and For the lens barrel having a constant circumferential angle with respect to the feeding position cam surface and different distances between the retracted position and the feeding position, only the lead angle of the helicoid screw was changed.

[0006]

In the present invention, even if the moving amount of the movable cylinder from the retracted position to the extended position is different, the rotation angle of the rotary cylinder is kept constant and only the lead angle of the helicoid screw is changed. It is no longer necessary to change the position of the position detection device operated by the cam. Further, since only the lead angle needs to be processed so as to correspond to each of the photographing lenses, other parts relating to the lens barrel can be commonly used.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 and 2 are sectional views of a camera showing an embodiment of the present invention. In both figures, a taking lens A having a first focal length (35 mm in this embodiment) is incorporated, and FIG. 1 shows a state where the taking lens A is extended to a photographing state, and FIG. 2 shows a non-photographing state. It shows the collapsed state.

FIG. 3 shows the structure of the taking lens A.
It is a perspective view including a partial perspective view. The taking lens A is composed of a front lens group 1 and a rear lens group 2. The front lens group 1 is held in the front lens group chamber 3. Rear lens group 2
Are held in the rear lens group chamber 4. A shutter 5 that performs an exposure operation is fixed to the front lens group chamber 3, and the front lens group chamber 3 is fixed to a movable barrel 6 that is movable in the photographing optical axis direction. The rear lens group chamber 4 is also fixed to the movable barrel 6. A male helicoid screw 6a is provided on the outer periphery of the rear end of the movable barrel 6.
Is formed, and is screwed with a female helicoid screw 7a formed on the inner circumference of the rotary cylinder 7. The rotating cylinder 7 has an outer circumference 7
While being fitted to the inner circumference 9a of the fixed barrel 9 at b, the one end 7c in the optical axis direction contacts the one end surface 9b of the fixed barrel 9 and the other end 7d.
Is in contact with the pressing plate 10. Therefore, the rotary barrel 7 is held with respect to the fixed barrel 9 so as to be rotatable about the optical axis without moving in the optical axis direction. The rectilinear guide 11 is fixed to the fixed barrel 9, and is in contact with the guide surface 6b formed on the movable barrel 6 at a surface 11a in the circumferential direction (direction orthogonal to the paper surface in FIG. 1). Gear 7 is attached to the outer circumference of the front part of the rotary cylinder.
e and a cam 7f are formed. The cam 7f is formed integrally with the rotary cylinder 7. When the rotary cylinder 7 is made of metal (die casting such as aluminum), the cam 7f is also made of the same metal. Alternatively, when the rotary cylinder 7 is made of plastic, the cam 7f is also made of plastic. By integrally forming the cam, whichever material is used, it is not necessary to separately prepare and assemble the cam and the cylinder, and the cam and the cylinder can be formed by one mold.

With the above arrangement, the taking lens moves in the optical axis direction as follows. First, the driving force from the motor 21 which is the lens barrel driving source is transmitted to the gear 7e via the gear train including the gears 22 and 23. As a result, the rotary cylinder 7 is rotated, but since the movable cylinder 6 is restricted in rotation by the rectilinear guide 11, the helicoid screws 7a and 6a are screwed together to move back and forth in the optical axis direction. The fixed barrel 9 is fixed to the body 12. Reference numeral 13 is a cover for covering the body and the like. As will be described later, the movable barrel 6 is in a non-photographing retracted position by a drive mechanism including gears 22, 23, 24, 25, and 26, and its front surface is covered with a barrier 14.

As shown in FIG. 3, the helicoid screw 6
The a and 7a are provided by cutting along the circumference of the movable cylinder 6 and the rotary cylinder 7. 4 and 5 show a state in which the taking lens B having the second focal length (28 mm in this embodiment) is incorporated. FIG. 4 shows a state in which the photographing lens is extended to a photographing state, and FIG. 5 shows a state in which the photographing lens is retracted to a non-photographing state. Figure 1 below
The difference between FIG. 2 and FIGS. 4 and 5 will be mainly described.

In FIG. 4, the taking lens B comprises a front lens group 101 and a rear lens group 102. The front group lens 101 is held in the front group lens chamber 103. The rear group lens 102 is held in the rear group lens chamber 104. The mounting portion of each lens chamber to the movable barrel 106 is configured to be constant regardless of the focal length of the taking lens. A male helicoid screw 106a is formed on the outer periphery of the rear end of the movable barrel 106, and is screwed with a female helicoid screw 107a formed on the inner periphery of the rotary barrel 107.

A cam 1 integrally provided on the outer circumference of the rotary cylinder 107.
07f has the same size as the cam 7f of the taking lens A. In the case of the taking lens A having the first focal length, the amount of projection between the shooting state and the collapsed state, that is, the amount of movement of the front end of the movable barrel 6 from the rear end surface of the barrier 14, that is, the front end surface of the pressing plate 10, is It is La as shown in FIG. On the other hand, in the case of the taking lens B having the second focal length, the amount of protrusion of the front end of the movable barrel 106 from the front end face of the pressing plate 10 is Lb as shown in FIG.
However, the positions in the non-imaging state are the same as shown in FIGS. 2 and 5. Therefore, in the present invention, the rotation angle of the rotary cylinder from the retracted position to the shooting position is set to the same angle θ (see FIG. 6), the lead angle of the helicoid screw is determined as follows according to the focal length of the shooting lens, and the above-mentioned extension Absorbing the difference in quantity. The lead angle of the taking lens A having the first focal length is α1, and the taking lens B having the second focal length is
And the radius of the rotary cylinder 7 and the rotary cylinder 107 is r (see FIG. 6).

[0013]

[Equation 1]

[0014]

[Equation 2]

Next, the drive system of the rotary cylinder will be described with reference to the drawings. 6 to 8 are cross-sectional views of a plane orthogonal to the optical axis and are plan views showing the drive mechanism of the rotary cylinder. FIG. 6 shows a state (corresponding to FIGS. 1 and 4) in which the photographing lens is extended to the photographing state, and a case where the photographing lens is retracted in the retracted direction will be described.

From the state shown in FIG. 6, the rotation of the lens barrel driving motor 21 is transmitted to the sun gear 22 via a gear train (not shown).
When the sun gear 22 rotates clockwise in the figure, the planet gear 23
Rotates counterclockwise. At this time, the connecting plate 24 that connects the sun gear 22 and the planetary gear 23 is subjected to a force that rotates clockwise around the sun gear 22. However, since the pin 24a planted in the connecting plate 24 is in contact with the locking surface 25a of the locking lever 25, the connecting plate 24 does not rotate and the planetary gear 23 is engaged with the gear 7e of the rotary cylinder 7. Rotate while maintaining. Since the planet gear 23 rotates counterclockwise, the rotary cylinder 7 rotates clockwise, and the movable cylinder 6 is screwed by the helicoid screws 7a and 6a.
Revolves around. In the illustrated state, the motor 2
The switch 30 for generating the control signal No. 1 is pressed by the cam surface 7h at one end of the cam 7f so that the contact pieces 30a and 30b are in contact with each other, and outputs a signal indicating that the photographing lens is in the photographing state. . When the rotary cylinder 7 starts to rotate in the clockwise direction, the contact pieces 30a and 30b which are pressed by the cam surface 7h and are in contact with each other are separated from each other. This state is shown in FIG. Further, the rotary cylinder 7 rotates clockwise, and the cam surface 7g at the end opposite to the cam surface 7h pushes the one end 25b of the locking lever 25. Then, the locking lever 25 rotates counterclockwise around the rotation center 25c. As a result, the engagement surface 25a of the engagement lever is disengaged from the pin 24a of the connecting plate 24, and the connecting plate 24 rotates clockwise around the sun gear 22 due to the rotational force of the sun gear 22. When the connecting plate 24 rotates clockwise, the engagement between the planet gear 23 and the gear 7e of the rotary cylinder 7 is released.
As a result, the rotation of the rotary cylinder 7 stops, and the movable cylinder 6 retracted by the helicoid screw stops at the retracted position shown in FIGS. 2 and 4. After this, the planetary gear 23 is the barrier drive gear 26.
Engage with. This state is shown in FIG. Barrier drive gear 2
When 6 rotates, the barrier 14 shown in FIGS. 2 and 4 is driven to a position that covers the front surface of the movable barrel 6 (106) by a drive mechanism (not shown), and when reaching the position that covers the front surface, the motor 21 is energized by a switch (not shown). To stop.

Next, the case where the movable barrel 6 is extended from the retracted position will be described. When the motor 21 rotates in the state of FIG. 8, the sun gear 22 rotates clockwise and the planet gear 2
The barrier drive gear 26 is rotated via the No. 3. The rotation of the barrier drive gear 26 causes the barrier 14 to move by a mechanism (not shown).
Retracts from the front surface of the movable cylinder 6 (106). Barrier 14
When the evacuation of the motor is completed, the motor 2
The rotation direction of 1 is reversed. Then, the sun gear 22 rotates counterclockwise, the connecting plate 24 also rotates counterclockwise, and the planetary gear 23 engages with the gear 7e of the rotary cylinder 7. Therefore, the rotation of the planetary gear 23 is transmitted to the gear 7e of the rotary cylinder 7,
The rotary cylinder 7 starts rotating counterclockwise. Then, since the locking lever 25 is urged clockwise by the spring (not shown) around the rotation center 25c, the locking lever 25 rotates clockwise, and the pin 24a of the connecting plate 24 and the locking surface 25a of the locking lever 25.
And are engaged. When the rotary cylinder 7 further rotates counterclockwise, the state shown in FIG. 7 is reached, and the cam surface 7h presses the contact piece 30a of the switch 30 as shown in FIG. 6 to contact the contact pieces 30a and 30b.
Come into contact with. As a result, the energization of the motor 21 is stopped and the movable cylinder 7 is stopped at a predetermined position.

In this embodiment, the cam 7f is integrally formed by connecting the cam surface 7g to the cam surface 7h. However, if the cam surfaces 7g and 7h are provided, the space between them is not particularly required. It may be provided separately for the cam including 7g and the cam including the cam surface 7h. Further, in the present embodiment, the rotational position of the rotary cylinder is detected by the leaf switch and the planetary gear as the driving force switching member, but the position may be detected by the encoder pattern and the brush.

[0019]

As described above, according to the present invention, even if the moving amount of the movable barrel from the retracted position to the extended position is different due to the different focal lengths, the rotation angle of the rotary barrel is constant and the helicoid is constant. Since it is formed by changing only the lead angle of the screw, it is not necessary to change the position of the position detecting device operated by the cam on the outer circumference of the rotating barrel for each different lens barrel. Further, since only the lead angle needs to be processed so as to correspond to each of the photographing lenses, other parts relating to the lens barrel can be commonly used. In other words, when using shooting lenses with different focal lengths, it is only necessary to change the shape of each lens chamber and the lead processing of the rotating cylinder, other parts can be used in common,
Mass production effect can be obtained. Further, the parts other than the helicoid screw of the rotary cylinder can be formed by die casting, plastic molding, or the like, and can be handled by only lead processing, machining, or changing the mold.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a state where a taking lens A having a first focal length is extended to a photographing state.

FIG. 2 is a cross-sectional view showing a state in which a taking lens A is retracted to a non-imaging state.

FIG. 3 is a perspective view showing a configuration of a taking lens A including a partial perspective view.

FIG. 4 is a cross-sectional view showing a state where a taking lens B having a second focal length is extended to a photographing state.

FIG. 5 is a cross-sectional view showing a state in which the taking lens B is retracted to a non-imaging state.

FIG. 6 is a plan view showing a drive mechanism in a state where a photographing lens is extended to a photographing state.

FIG. 7 is a plan view showing a drive mechanism in a state in which the taking lens is in a shooting state and a non-shooting state.

FIG. 8 is a plan view showing a driving mechanism in a state in which a photographing lens is retracted in a non-photographing state.

[Explanation of symbols]

 6 ...... Movable cylinder 6a ...... Male helicoid screw 7 ...... Rotating cylinder 7a ...... Female helicoid screw 7e ...... Gear 7f ...... Cam 7h, 7g ...... Cam surface 9 ...... Fixed cylinder

Claims (4)

[Claims] 1. A rotary cylinder having a female helicoid screw, a movable cylinder holding a taking lens and having a male helicoid screw,
A lens barrel that includes a straight guide that restricts rotation of the movable barrel and that moves the movable barrel forward and backward in the optical axis direction by rotation of the rotary barrel, wherein the movable barrel is in a non-photographing retracted position and a photographing state. A retractable position cam surface for detecting that the movable barrel is in the retracted position on the outer circumference of the rotary cylinder and a retractable position cam for detecting that the movable cylinder is in the retracted position. A helicoid screw lead for a lens barrel having a surface and a constant circumferential angle between the retracted position cam surface and the retracted position cam surface and different distances between the retracted position and the retracted position. A lens barrel characterized by being formed by changing only the corners. 2. The lens barrel according to claim 1, wherein at least the cam portion of the rotary barrel is integrally formed of metal. 3. The lens barrel according to claim 1, wherein the helicoid screw is cut. 4. The lens barrel according to claim 1, wherein at least the cam portion of the rotary barrel is made of plastic.