JP2002107599A - Collapsible mount type lens barrel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate trouble that load for rotating a cam barrel is increased because the tilt angle of a cam groove becomes large in the case of making the diameter of the cam barrel smaller in a collapsible mount type lens barrel using the cam barrel. SOLUTION: Cam grooves 11 and 12 in which the cam pins of a 1st group lens frame and a 2nd group lens frame are fit are provided on the cam barrel 2. Three sets of cam grooves 11 and 12 are formed at the intervals of about 120 deg. respectively in the circumferential direction of the cam barrel 2. Furthermore, by forming the cam grooves 11 and 12 over the range of >= about 120 deg. in the circumferential direction of the cam barrel 2, the tilt angles β1 and β2 of the cam grooves 11 and 12 to a plane perpendicular to an optical axis are made small.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a retractable lens barrel, and more particularly to a lens moving mechanism for zooming by moving a plurality of moving lenses back and forth by a cam mechanism in the retractable lens barrel.

[0002]

2. Description of the Related Art JP-A-2000-89080 discloses that
A collapsible lens barrel in which two moving lens frames are moved in the front-rear direction by one cam barrel is disclosed. As shown in FIG. 5, the lens barrel has a straight groove 115 formed on the inner peripheral surface of the fixed frame 114 in the optical axis direction.
15, three cam pins 13 protruding from the moving frame 120.
The three cam pins 138 projecting from the sixth and second lens frames 130 are fitted respectively. The cam pins 136 and 138 pass through the rectilinear grooves 115 and
6 cam grooves 140, 141. Cam groove 1
Reference numerals 40 and 141 are formed in a non-linear shape determined in accordance with the movement trajectory of the movable barrel 120 and the second lens group frame 130. The cam cylinder 116 is rotatably provided on the outer periphery of the fixed cylinder 114. A gear 144 is formed on the outer periphery of the cam cylinder 116 and is connected to a reduction gear train 150 having a drive motor 118.

Accordingly, when the driving motor 118 is driven, the driving force rotates the cam cylinder 116 via the reduction gear train 150, whereby the moving frame 120 is rotated.
The second lens frame 130 and the second group lens frame 130 move along the shapes of the cam grooves 140 and 141 while being guided by the rectilinear grooves 115, and zooming is performed. As described above, the driving of the moving frame 120 and the second group lens frame 130 is performed by the
Since the configuration can be performed only by using the two components 6 and 6, a lens barrel with a small number of components can be realized.

[0004]

However, the conventional collapsible lens barrel has the following problems.

In order to reduce the size of the lens barrel, it is necessary to reduce the diameter of the cam barrel 116. The problem in reducing the diameter of the cam cylinder 116 is the angle of inclination of the cam grooves 140 and 141 with respect to a plane perpendicular to the optical axis. When the diameter of the cam cylinder 116 is reduced, the rotation of the cam cylinder 116 in the cam grooves 140 and 141 is reduced. If the formation range in the direction is the same, this inclination angle needs to be set large. When three cam pins 136 and 138 are provided, the cam grooves 140 and 141 into which the cam pins 136 and 138 fit are usually used.
Each of the cam pins 136 and 138 is formed in three sets at an interval of about 120 ° over a range of about 120 °. However, when the cam cylinder 116 is reduced in diameter and the inclination angle is increased, a load when rotating the cam cylinder 116 is increased. Therefore, a large driving motor 118 having a larger driving force is required. This is an obstacle to downsizing the cylinder. Therefore, the cam cylinder 11
Reducing the diameter of 6 and contradicting the need for a large drive motor 118 with a large drive force.

An object of the present invention is to provide a collapsible lens barrel in which the diameter of the lens barrel can be reduced without increasing the inclination angle of the cam groove. It is.

[0007]

According to a first aspect of the present invention, there is provided a collapsible lens barrel which holds a lens and is provided with a plurality of cam pins at predetermined angles at substantially equal intervals in a circumferential direction. And a plurality of cam grooves that are rotatable around the optical axis to move each of the moving frames in the optical axis direction, and are formed on a peripheral surface portion with cam pins of the moving frame to be fitted respectively. And a fixed cylinder formed with a groove that extends in a direction substantially along the optical axis direction and into which the cam pins of the moving frame are fitted, and each cam groove for each cam pin in the cam cylinder, It is characterized in that it is formed over a range of angles larger than the predetermined angle in the circumferential direction of the cam cylinder.

According to this structure, each cam groove for each cam pin is formed over a range of an angle larger than a predetermined angle in the circumferential direction of the cam cylinder (the circumferential interval between the cam pins). Is formed in an angle range equal to the circumferential interval angle between the cam pins, the inclination angle of the cam groove can be reduced. As a result, the inclination angle of the lens barrel can be reduced without increasing the inclination angle of the cam groove. The diameter can be reduced.

According to a second aspect of the present invention, in the retractable lens barrel according to the first aspect, the plurality of moving frames are three first frames.
And a second moving frame having three second cam pins, and each of the first cam pins is fitted into the cam cylinder. The first cam groove and three second cam grooves into which the respective second cam pins are fitted are formed, and the first cam groove and the second cam groove are formed in the circumferential direction of the cam cylinder. Is formed over a range of angles larger than 120 °.

[0010] The third aspect of the present invention is the first or second aspect.
Wherein the start position and the end position of the cam groove for each moving frame formed in the circumferential direction around the optical axis are substantially the same. That is, in the case of the collapsible lens barrel according to the second aspect, the first cam groove and the second cam groove are located at the start and end positions of the cam groove formation in the circumferential direction around the optical axis. Are substantially the same as each other.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is an exploded perspective view of a retractable lens barrel according to an embodiment of the present invention, FIG. 2 is a view showing a shape of a cam groove of a cam barrel in the retractable lens barrel, and FIGS. 4) is a sectional view of a main part of the lens barrel showing a collapsed state and a use state of the collapsible lens barrel, and FIGS. 4A and 4B are collapsed states and use of the collapsible lens barrel. It is a perspective view of the lens barrel which shows a state.

The retractable lens barrel 1 has an optical system structure in which the first lens unit L1 and the second lens unit L2 are moved back and forth in the direction of the optical axis A by the cam barrel 2 to change the focal length. The CCD 3 is provided at the image forming position. These first group lens L1 and second group lens L2
Are held by the first group lens frame 4 and the second group lens frame 5, respectively. The CCD 3 is attached to a back plate 6 fixed at a predetermined position.

The first group lenses L1 and L2 are fixed at predetermined positions.
A plurality of rectilinear grooves 8 are formed on the outer circumference of the fixed cylinder 7 for guiding the group lens L2 along the direction of the optical axis A. In the rectilinear grooves 8, a first group lens frame as a first moving frame is provided. A cam pin (first cam pin) 9 protruding from the camera unit 4 and a cam pin (second cam pin) 10 protruding from the second lens group frame 5 as a second moving frame are fitted to each other. Three cam pins 9 and 10 are protruded at equal intervals (approximately 120 ° interval) on the outer peripheral portion of the first lens frame 4 and the second lens frame 5, and three straight grooves 8 are also provided at equal intervals. Is formed. As a result, the first group lens frame 4 and the second group lens frame 5 are stably supported by the rectilinear grooves 8 via the three cam pins 9 and 10, so that they can move back and forth in the direction of the optical axis A. . Further, the cam pins 9 and 10 penetrate the straight groove 8 and are fitted into cam grooves 11 and 12 formed on the inner periphery of the cam cylinder 2. The cam grooves 11 and 12 are formed in a non-linear shape determined according to the movement locus of the first lens frame 4 and the second lens frame 5.

The cam cylinder 2 is rotatably provided on the outer periphery of the fixed cylinder 7. A gear 13 is provided on the outer periphery of the cam cylinder 2.
Is formed, and the driving force transmission gear 14 is meshed with the gear 13. The driving force transmission gear 14 is connected to an output shaft of a driving motor 16 via a reduction gear train 15. Therefore, when the drive motor 16 is driven, the drive force is transmitted from the reduction gear train 15 to the drive force transmission gear 14, and the cam cylinder 2 is rotated. As a result, the first group lens frame 4 and the second group lens frame 5 move along the shapes of the cam grooves 11 and 12 while being guided by the rectilinear grooves 8, so that zooming is performed.

The focus adjustment lens unit L 3 is held by a third unit lens frame 17. This third group lens frame 17
Are slid in the direction of the optical axis A along two guide poles 19 and 20 which are disposed in parallel with the optical axis A, and are fixed at both ends between the fixed cylinder 7 and the guide pole holding frame 18. It is freely configured. The guide pole holding frame 18 is fixed to the fixed cylinder 7 by screws while holding the two guide poles 19 and 20. The stepping motor 21 for moving the focus adjustment lens group L <b> 3 has a lead screw part 22 integrally formed on the rotation shaft of the stepping motor 21 and is fixed to the fixed cylinder 7. A screw member 23 engaged with the third lens group frame 17 is screwed into the lead screw portion 22. The rotation of the lead screw portion 22 causes the third lens group frame 17 to move linearly in the front-back direction along the optical axis A.

FIG. 2 is a development view of a cam groove formed in the cam cylinder 2. As shown in the figure, the cam cylinder 2 has three first cam grooves 11 (11
a, 11b, 11c) and three second cam grooves 12 (12a, 12b, 12c) for the second group lens frame 5 are formed at approximately 120 ° intervals. First cam groove 11
Is formed over the range of (120 + α ゜) in the circumferential direction of the cam barrel 2 from the retracted position to the position of Tele beyond the position of Wide, the cam groove portion 11d for performing zooming, and the first lens unit. It is distinguished from the cam groove 11e for collapsing the frame 4. Similarly, the second cam groove 12 extends from the retracted position beyond the Wide position to the Tele position.
Is formed over the range of (120 + α２) in the circumferential direction of the cam barrel 2 up to the position, and a cam groove 12d for performing zooming and a cam groove 12e for retracting the second lens group frame 5 are formed. Be distinguished. That is, the first and second cam grooves 11 and 12 are provided three at intervals of approximately 120 ° inside the cam cylinder 2, but the formation range is more than 120 ° and extra by α °. And the cam groove 11,
12, the start points 11s, 12f and the end points 11f, 12f of the cam grooves 11, 12 are substantially at the same position in the circumferential direction and the optical axis direction, respectively. As a result, unlike the conventional case, even if the diameter of the cam cylinder 2 is reduced, the formation range of the cam grooves 11 and 12 can be increased to 120 ° or more, so that the cam grooves 11 and 12 are perpendicular to the optical axis. The inclination angles β1 and β2 with respect to the surface can be reduced. Therefore, since the cam barrel 2 can be driven with a low load when driven, there is no need to increase the size of the drive motor 16, and the lens barrel can be reduced in size.

In addition, the cam pins 9 and 10 are connected to the first cam groove 11 and the second cam groove 1 at the time of assembly.
2 is an introduction groove for introduction. The operation of the retractable lens barrel 1 configured as described above will be described.

The drive motor 16 is rotated to rotate the cam cylinder 2 from the retracted state to the wide state. A sectional view of the retractable lens barrel 1 at that time is shown in FIG. By the rotation of the cam barrel 2 from the collapsed state, the first lens group frame 4
The vehicle goes straight to the left in FIG. Furthermore, Wide ~ Te
When the cam barrel 2 is rotated in the range up to le, the first lens frame 4 and the second lens frame 5 move back and forth in the direction of the optical axis A along the cam grooves 11 and 12, so that zooming can be performed. In the Tele state, the cam cylinder 2 exceeds the rotation angle of 120 ° from the retracted position, and further rotates α °. For the focus adjustment, the stepping motor 21 is rotated by a predetermined amount according to the zooming position,
This is performed by moving the third lens group frame 17.

Conversely, when the cam barrel 2 is rotated from the Wide position toward the collapsed state, the first lens frame 4 and the second lens frame 5 move rearward along the cam grooves 11 and 12 along the optical axis. As a result, the retracted state shown in FIG. In addition, FIG.
FIG. 4B shows a perspective view of the retracted state.

As described above, according to the present embodiment, the limited space of the cam barrel 2 for the cam grooves 11 and 12 in which the cam pins 9 and 10 of the first lens frame 4 and the second lens frame 5 are fitted. Is effectively used, and is formed over a range of about 120 ° or more in the rotation direction of the cam barrel 2 from the retracted position to the Tele state, so that the cam barrel 2 is formed in order to reduce the size of the retractable lens barrel 1. When reducing the diameter,
It is not necessary to increase the inclination angles of the cam grooves 11 and 12.
Therefore, it is not necessary to increase the size of the drive motor 16, and the collapsible lens barrel 1 can be reduced in size.

The cam grooves 11, 12 provided in the cam cylinder 2
Is not limited to the shape described in the present embodiment. The number of lens frames 4 and 5 driven by the cam barrel 2 is not limited to two, but may be three.

Further, the case where the collapsible lens barrel 1 is used for a digital still camera equipped with a CCD 3 has been described, but the same applies when the collapsible lens barrel 1 is used for a conventional silver halide film. The effect of is obtained.

[0023]

As described above, according to the collapsible lens barrel of the present invention, each cam groove for each cam pin in the cam cylinder is formed at a predetermined angle in the circumferential direction of the cam cylinder (angle between the cam pins in the circumferential direction). By forming over a larger angle range, even when the diameter of the cam barrel is reduced to reduce the size of the lens barrel, it is not necessary to increase the inclination angle of the cam groove. Therefore, it is not necessary to increase the size of the drive motor, and a remarkable effect of reducing the size of the lens barrel can be obtained.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a retractable lens barrel according to an embodiment of the present invention.

FIG. 2 is a view showing a shape of a cam groove of a cam barrel in the collapsible lens barrel.

FIGS. 3A and 3B are cross-sectional views of a main part of the retractable lens barrel, showing a retracted state and a used state of the lens barrel.

FIGS. 4A and 4B are perspective views of the retractable lens barrel showing the retracted state and the used state of the retractable lens barrel.

FIG. 5 is an exploded perspective view of a conventional lens barrel.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 collapsible lens barrel 2 cam barrel 3 CCD 4 1st lens frame (moving frame) 5 2nd lens frame (moving frame) 7 fixed barrel 8 rectilinear groove 9 cam pin (first cam pin) 10 cam pin (second cam pin) 11) Cam groove (first cam groove) 12 Cam groove (second cam groove) 16 Drive motor L1 First group lens L2 Second group lens

Claims (3)

[Claims] 1. A plurality of moving frames each holding a lens and having a plurality of cam pins provided at predetermined angles at substantially equal intervals in a circumferential direction, and a light source for moving each of the moving frames in the optical axis direction. A cam barrel, which is rotatable around an axis and has a plurality of cam grooves formed on a peripheral surface thereof and into which the cam pins of the moving frame are respectively fitted, and a cam pin of the moving frame extending in a direction substantially along the optical axis direction. A fixed cylinder having a groove to be fitted therein, wherein each cam groove for each cam pin in the cam cylinder is formed over a range of an angle larger than the predetermined angle in a circumferential direction of the cam cylinder. The retractable lens barrel. 2. The moving frame includes a first moving frame having three first cam pins, and a second moving frame having three second cam pins. The cam barrel is formed with three first cam grooves into which each first cam pin is fitted and three second cam grooves into which each second cam pin is fitted. 2. The collapsible lens barrel according to claim 1, wherein the cam groove and the second cam groove are formed over an angle range larger than 120 [deg.] In the circumferential direction of the cam barrel. 3. The cam groove according to claim 1, wherein the starting position and the ending position of the cam groove for each moving frame formed in the circumferential direction around the optical axis are substantially the same. Retractable lens barrel.