JP4441763B2 - Lens barrel of optical device - Google Patents

Description

  The present invention provides an optical device that moves a lens in the optical axis direction, such as a zoom lens device capable of continuously changing a focal length, for example, and a lens mirror having a cam that transmits a driving force to the lens. Related to the tube.

  For example, a zoom lens device is a device that continuously changes the focal length by moving the lens back and forth in the optical axis direction, and there is one in which a cam mechanism is used as a moving mechanism of the lens. A typical mechanism structure is a double structure of a fixed cylinder that does not rotate and a cam cylinder that rotates relative to the fixed cylinder. In some cases, a bottomed cam groove is formed in a lens barrel, a cam follower is provided in a lens frame holding a lens, and the leading end of the cam follower is inserted into a cam groove through a guide hole. That is, when the cam cylinder is rotated with respect to the fixed cylinder, the cam follower is guided from both the guide hole and the cam groove, and the amount of movement at the time of advance and retreat is adjusted. By making the curve an appropriate shape, the lens can be continuously moved by a predetermined movement amount. If each of the plurality of lenses is moved while maintaining the optical function by this mechanism structure, the zooming operation can be performed.

  As a zoom lens apparatus provided with this kind of cam structure, conventionally, for example, a zoom lens barrel of a camera described as the prior art of Patent Document 1 or a zoom lens barrel described as the prior art of Patent Document 2 and so on. FIG. 5 is a view for explaining the schematic structure of this type of conventional zoom lens apparatus. And a rotating cylinder 3 provided. A cam hole 2 a is formed in the fixed cylinder 2 by a long hole along the optical axis direction, and a cam groove (not shown) having an appropriate cam curve is formed on the inner surface of the rotating cylinder 3. A cam pin planted in a lens frame holding the lens so as to face outward is inserted through the cam hole 2a and the tip thereof is inserted into the cam groove. For this reason, when the rotating cylinder 3 is rotated with respect to the fixed cylinder 2, the cam pin is guided in the optical hole direction by the cam hole 2a and is moved by a predetermined movement amount by being guided by the cam curve of the cam groove. The lens moves forward and backward in the optical axis direction.

  By the way, as shown in FIG. 6, the rotating cylinder 3 is disposed at a position between a flange portion 2b formed to project outward from the distal end portion of the fixed cylinder 2 and the base plate 1, and is rotatably supported. Has been. In addition, the fixed cylinder 2 is provided with a bracket portion 2c projecting inwardly at the rear end portion, and a set screw (not shown) through which an attachment hole 1a formed in the base plate 1 is inserted. Is attached to the base plate 1.

Japanese Patent Publication No. 6-25816 Japanese Patent Publication No. 6-100708

  However, in the above-described conventional zoom lens device, the following problem occurs in the mounting structure of the fixed cylinder 2 to the base plate 1. The fixed cylinder 2 is fixed by abutting the bracket portion 2c formed at the rear end against the base plate 1, and the rear end of the fixed cylinder 2 is abutted against the front surface of the base plate 1. On the other hand, the rear end portion of the cam hole 2 a is located in front of the rear end portion of the fixed cylinder 2. For this reason, the cam pin guided to the cam hole 2a is positioned in front of the base plate 1 in a state of being retracted to the last part.

  Incidentally, in order to reduce the size of an optical apparatus such as a zoom lens apparatus, it is required to shorten the length in the optical axis direction. In the conventional structure described above, the retracted position of the cam pin is limited by the rear end portion of the cam hole 2a. Therefore, the length of the optical device in the optical axis direction at the position where the cam pin contacts the rear end portion of the cam hole 2a. Was determined and could not be shortened any further. In order to allow the cam pin to retract until it comes into contact with the base plate 1, it is conceivable that the cam hole 2a is formed by cutting from the rear end portion of the fixed cylinder 2. However, with such a structure, the fixed cylinder 2 is formed. This is not preferable because the strength of the cam pin becomes insufficient and the guide of the cam pin becomes unstable.

  Accordingly, the present invention can form the rear end portion of the guide hole formed in the fixed cylinder up to the front surface position of the base plate without reducing the strength of the fixed cylinder, and the retracted position of the cam pin immediately before the base plate. It is an object of the present invention to provide a lens barrel of an optical device capable of shortening the length in the optical axis direction.

  As technical means for achieving the above object, a lens barrel of an optical device according to the present invention is an optical device that moves a lens in an optical axis direction, a moving frame that holds the lens, a base plate, Provided with a guide hole for guiding the moving frame in the optical axis direction, a fixed cylinder in which a part of the end portion is penetrated into the base plate, and provided coaxially with respect to the fixed cylinder, A cam cylinder having a cam groove, connecting and fixing the fixed cylinder and the base plate, and the moving frame is provided with a cam follower that fits into the cam groove and the cam hole. A communication portion that connects portions divided by the guide hole at an end portion of the guide hole is provided in a portion penetrating the base plate.

  That is, the guide hole is formed up to the end of the fixed cylinder, the fixed cylinder is connected to the base plate, and the end of the guide hole is connected.

  According to the lens barrel of the optical device according to the present invention, even when the guide hole is formed up to the end position of the fixed cylinder, the strength of the fixed cylinder may be reduced because there is a portion that penetrates the base plate. Absent. Therefore, the cam follower fitted in the guide hole can be retracted to the position immediately before or in contact with the base plate. Since the length of the optical device such as a zoom lens device in the optical axis direction is limited at the retracted position of the cam follower, the length of the optical device in the optical axis direction can be shortened.

  The lens barrel of the optical apparatus according to the present invention will be specifically described below based on the preferred embodiments shown in the drawings. In this embodiment, a zoom lens device is illustrated as an optical device.

  2 to 4 are views showing the structure of a camera provided with this zoom lens device. This camera includes a first group lens 21, a second group lens 22, and a third group lens 23. The first group lens 21 and the second group lens 22 have a predetermined optical relationship in the optical axis direction. The zoom operation, that is, the zooming operation is performed by holding and moving. The third group lens 23 is advanced and retracted along with the second group lens 22 during zooming operation, and is advanced and retracted in the optical axis direction with respect to the second group lens 22 during focusing operation.

  The group lenses 21, 22, and 23 are accommodated in a substantially cylindrical fixed cylinder 24. The first group lens 21 is held by the first lens moving frame 21a. The outer periphery of the first lens moving frame 21a is provided with an input arm portion 21b extending rearward and a cam pin that is a cam follower directed outward at an appropriate position of the input arm portion 21b. 25 is protruding. The cam pin 25 is configured such that a roller is rotatably supported by a pin implanted in the input arm portion 21b. The second group lens 22 is arranged behind the second group lens 21, and is held by the second lens moving frame 22a. The outer periphery of the second lens moving frame 22a is provided with an input arm portion 22b extending rearward and a cam pin which is a cam follower directed outward at an appropriate position of the input arm portion 22b. 26 is protruding. The cam pin 26 is configured such that a roller is rotatably supported by a pin implanted in the input arm portion 22b. These cam pins 25 and 26 are inserted further into the fixed cylinder 24 through a straight cam hole 24a as a guide hole formed by a long hole whose longitudinal direction is the optical axis direction, and further outward from the outer peripheral surface of the fixed cylinder 24. It is protruding.

  The fixed cylinder 24 is attached to the base plate 20 of the camera body, and a flange portion 24b directed outward is formed at the tip. A rotating cylinder 27 as a cam cylinder is provided between the flange portion 24b and the base plate 20 so as to be rotatable with respect to the fixed cylinder 24. A first cam groove 27a and a second cam groove 27b having an appropriately shaped cam curve are formed on the inner surface of the rotating cylinder 27, and the tip of the cam pin 25 connected to the first group lens 21 is The distal end portion of the cam pin 26 inserted into the first cam groove 27a and connected to the second group lens 22 is inserted into the second cam groove 27b. A drive gear portion 28 is provided at the outer rear end portion of the rotating cylinder 27. As shown in FIG. 2, the output rotation of the variable power drive motor 29 is transmitted via an appropriate gear train 30. Is transmitted to.

  FIG. 1 is a schematic exploded perspective view showing the relationship between the fixed cylinder 24, the base plate 20, and the rotating cylinder 27. The fixed cylinder 24 is attached to a position surrounding an aperture 20a formed on the base plate 20. FIG. A tongue piece 24c is formed at the rear end portion of the fixed cylinder 24 so as to protrude rearward with an appropriate width, and the linear cam hole 24a extends to a position facing the tongue piece 24c. . By the way, when the tongue piece 24c is not provided, the rear end position of the straight cam hole 24a is fixed because the portion between the rear end position and the rear end of the fixed cylinder 24 needs to secure strength. It is necessary to provide an appropriate distance from the rear end of the tube 24. On the other hand, when the tongue piece portion 24c is provided, the tongue piece portion 24c exists even if the rear end portion of the straight cam hole 24a is extended to the vicinity of the rear end portion of the fixed cylinder 24 not including the tongue piece portion 24c. By this, sufficient strength can be secured. That is, the position of the rear end of the straight cam hole 24a can be a position that enters the portion of the tongue piece 24c, or a position that does not enter the tongue piece 24c, and the tongue piece 24c is It may be up to the vicinity of the rear end of the fixed cylinder 24 not included.

  On the other hand, a locking hole 20b for receiving the tongue piece 24c is formed in the periphery of the aperture 20a of the base plate 20 by a through hole, and the tongue piece 24c is inserted into the locking hole 20b. The rear end portion of the fixed cylinder 24 is in close contact with the base plate 20. A bracket portion 24d is projected from the rear end portion of the fixed cylinder 24 so as to be directed inward (see FIGS. 2 to 4), and a mounting hole 20c formed around the aperture 20a of the base plate 20 is inserted therethrough. A fixed cylinder 24 is fixed to the base plate 20 by tightening a set screw (not shown) to the bracket portion 24d.

  Further, as shown in FIGS. 2 to 4, a motor bracket 8 is attached to the second lens moving frame 22a, and a focusing drive motor 9 is attached to the motor bracket 8. The second lens moving frame 22a supports guide rods 5a and 5b whose longitudinal direction is parallel to the optical axis. The driving shaft 10 of the focusing drive motor 9 is inserted through the frame holder 6 provided in the third lens frame 23a, and the frame 11 linked to the frame holder 6 is incorporated so as not to fall off the frame holder 6. A female screw portion formed on the inner surface of the connecting piece 11 is screwed with the male screw portion of the drive shaft 10. The guide rod 5b is inserted into a guide portion 7 provided in the third lens frame 23a, and the guide rod 5a is inserted into a fork portion (not shown) formed in a fork shape in the third lens frame 23a. I'm allowed.

  The operation of the zoom lens apparatus including the lens barrel according to the present invention configured as described above will be described below.

  In order to assemble the fixed cylinder 24, the rotary cylinder 27, and the base plate 20, the rotary cylinder 27 is put on the fixed cylinder 24 and the rotary cylinder 27 is brought into contact with the flange portion 24b. In this state, since the tongue piece 24c protrudes from the rear end portion of the rotating cylinder 27, the tongue piece 24c is inserted into the locking hole 20b of the base plate 20, and the bracket portion 24d is brought into contact with the base plate 20. If the set screw inserted through the mounting hole 20c of the base plate 20 is tightened to the bracket portion 24b, the fixed cylinder 24 is fixed to the base plate 20, and the rotary cylinder is rotatable with respect to the fixed cylinder 24. 27 is supported.

  Next, with reference to FIGS. 2 to 4, the operation of the camera provided with this zoom lens device will be described. FIG. 2 shows a case where the camera is in a retracted state where the camera is not used for photographing. The first group lens 21, the second group lens 22, and the third group lens 23 are all retracted to the last part. In this state, the cam pin 26 linked to the second group lens 22 is retracted to the position just before the base plate 20 at the rear end portion of the linear cam hole 24a. That is, the straight cam hole 24a is formed up to a position immediately before the base plate 20, and is formed up to a position behind the structure in which the tongue piece portion 24c is not provided. The cam pin 25 connected to the first group lens 21 is rearward of the straight cam hole 24a and retracts to a position close to the cam pin 26. That is, the cam pin 26 is retracted to a position where it cannot be retracted any further, and the length of the zoom lens device in the optical axis direction is the shortest.

  In this retracted state, when the variable power drive motor 29 operates and the output rotation is transmitted to the drive gear portion 28, the rotating cylinder 27 rotates with respect to the fixed cylinder 24. Since cam pins 25 and 26 penetrating the straight cam hole 24a of the fixed cylinder 24 are inserted into the cam grooves 27a and 27b formed in the rotating cylinder 27, the cam pin 25 is inserted into the first cam groove 27a and the cam pin 26. Are moved in the direction of the optical axis by being guided by the second cam grooves 27b. For this reason, the first group lens 21 connected with the cam pin 25 and the second group lens 22 connected with the cam pin 26 move with different movement amounts while maintaining a predetermined optical relationship, and the telephoto position shown in FIG. And the zooming operation is performed between the wide-angle position shown in FIG.

  The third group lens 23 moves along with the second group lens 22 because the bracket 8 and the guide rods 5a and 5b are attached to the second lens moving frame 22a of the second group lens 22. When a focusing operation is performed, the drive motor 9 is operated to rotate the drive shaft 10 based on distance information to a subject obtained by a distance measuring device (not shown). The drive shaft 10 is formed with a male screw portion 10a. Since the female screw portion 11a of the piece 11 connected to the male screw portion 10a is screwed, the connected piece 11 is connected to the drive shaft by the rotation of the drive shaft 10. It moves along the direction parallel to the optical axis along 10. Since the connecting frame 11 is accommodated in the frame holder 6 formed on the third lens frame 23a, the third lens frame 23a is moved by the movement of the connecting frame 11, and the third group lens 23 is moved in the optical axis direction. . The photographing optical system is brought into focus by the movement of the third group lens 23. Note that the moving direction of the linked pieces 11 is changed according to the rotation direction of the drive shaft 10, and the third group lens 23 can be advanced and retracted. When each lens group 21, 22, 23 is in the retracted state, as shown in FIG. 2, the third group lens 23 is moved to a position close to the second group lens 22, and the optical axis direction is moved. The overall length is shortened to make the camera thinner.

  In the embodiment described above, the tongue 24c is formed at the rear end of the fixed cylinder 24. However, the linear cam hole 24a that is a guide hole is formed by releasing the rear end of the fixed cylinder 24. In addition, the rear end portion of the fixed cylinder 24 in which the straight cam hole 24a is not formed can be connected to the base plate 20.

  According to the lens barrel of the optical device according to the present invention, the length in the optical axis direction in the retracted state such as when the optical device is stored or carried can be shortened as much as possible, thereby contributing to the miniaturization of the optical device.

1 is a schematic exploded perspective view illustrating a structure of a lens barrel of an optical device according to the present invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic longitudinal sectional view of a camera equipped with a zoom lens apparatus having a lens barrel according to the present invention, showing a state in which a photographing optical system is in a retracted position. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic longitudinal sectional view of a camera equipped with a zoom lens apparatus having a lens barrel according to the present invention, showing a state where a photographing optical system is in a telephoto position. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic longitudinal sectional view of a camera equipped with a zoom lens apparatus having a lens barrel according to the present invention, showing a state where a photographing optical system is at a wide angle position. It is a schematic exploded perspective view explaining the structure of the conventional lens barrel, and is a figure equivalent to FIG. FIG. 6 is a schematic cross-sectional view taken along a plane including the optical axis of the lens barrel shown in FIG.

Explanation of symbols

20 Foundation board
20a aperture
20b Locking hole
20c Mounting hole
21 First lens group
22 Second lens group
23 Third lens group
24 Fixed cylinder
24a Linear cam hole (guide hole)
24b Flange
24c tongue
24d bracket
25 Cam Pin (Cam Follower)
26 Cam Pin (Cam Follower)
27 Rotating cylinder
27a 1st cam groove
27b Second cam groove

Claims (1)

In an optical device that moves the lens in the optical axis direction,
A moving frame to hold the lens;
A base plate,
A fixed cylinder provided with a guide hole for guiding the moving frame in the optical axis direction, and having a part of the end portion penetrated into the base plate;
A cam cylinder provided coaxially with respect to the fixed cylinder and having a cam groove;
The fixed cylinder and the base plate are connected and fixed,
The moving frame is provided with a cam follower that fits into the cam groove and the cam hole, and a communication portion that connects the portions of the fixed cylinder divided by the guide hole at the end of the guide hole, A lens barrel of an optical device, wherein the lens barrel is provided in a portion penetrating the base plate.

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