JP3869881B2 - Lens barrel and optical equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a lens barrel that moves a lens housed in a lens holding portion in the optical axis direction, and an optical apparatus including the lens barrel .
[0002]
[Prior art]
Conventionally, as this type of lens driving device,
1) The lens holding frame is moved in the optical axis direction by meshing with a stepping motor having a feed screw arranged in parallel with the optical axis and a rack member provided on the lens holding frame.
[0003]
2) A lens holding frame that is linked to the cam member and supported by a guide member that is arranged in parallel with the optical axis by a DC motor having a gear reduction and a cam member that is linked to the gear reduction. Guided by the cam of the cam member and moved in the optical axis direction.
Etc.
[0004]
[Problems to be solved by the invention]
However, the above conventional example has the following problems.
[0005]
In the lens driving device according to the above 1), the feed screw of the stepping motor and the rack member are engaged with each other, and an electronic cam for determining the position of the moving lens group is required, and the control is extremely complicated. Further, if the pitch of the feed screw is made fine in order to increase the feed accuracy of the moving lens group, tooth skipping is likely to occur due to external force, and control becomes impossible.
[0006]
In the lens driving device in which the DC motor having the gear reduction device of 2) and the cam member are interlocked, the position of the moving lens group cannot be specified as it is, so that the moving range of the cam member is mechanically defined, and the interlocking gear portion. It was necessary to absorb the impact at the time of mechanical end collision by providing a friction mechanism. Further, in order to obtain the position information of the moving lens group, it is necessary to interlock the encoder member and the like, and there is a problem that the mechanical mechanism becomes extremely complicated.
[0007]
The present invention has been made to solve the above-described problems, and an object thereof is to obtain a lens barrel in which a control system and a mechanical mechanism in lens driving are simplified, and an optical apparatus to which the lens barrel is applied. .
[0008]
[Means for Solving the Problems]
The lens barrel of the invention of claim 1 includes a first interlocking member, and the first lens holding frame which holds a first lens, a second interlocking member, holds the second lens A second lens holding frame to
A stepping motor having a first rotation axis parallel to the optical axis direction, a reduction gear having a second rotation axis parallel to the optical axis direction, and rotating to reduce the output of the stepping motor; A third axis of rotation parallel to the axial direction;
A cam ring that rotates in conjunction with the reduction gear, is parallel to the optical axes of the first and second lenses and is arranged radially outside the first and second lens holding frames, and a photosensor; Have
The cam ring is in contact with the first and second interlocking pieces on the outer peripheral surface thereof, and a cam groove for guiding the first and second lens holding frames in the optical axis direction in a predetermined relationship;
The cam ring protrudes in the radial direction, and includes a protrusion for detecting a reference position of rotation of the cam ring by the photosensor, and the number of pulses with the reference position detected by the photosensor as an initial position. The amount of movement of the first and second lens holding frames is determined.
[0009]
An optical apparatus according to a second aspect of the invention is characterized by including the lens barrel of the first aspect.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described below.
Embodiment 1 FIG. 1 is a perspective view of a lens driving device according to Embodiment 1 of the present invention. In FIG. 1, 1 is a lens holding frame that holds a moving lens group 1a as a compensator , and 2 is a moving lens group 2a as a variable power lens. This is a lens holding frame that holds the lens.
[0014]
Reference numeral 3 denotes a cam ring as cam means having a third rotating shaft parallel to the optical axis direction in which cam grooves 3a and 3b for guiding the movable lens groups 1a and 2a are formed. A pulse motor as drive means and A gear portion 3c for interlocking is provided. The interlocking pieces 1-1 and 2-1 of the lens holding frames 1 and 2 are pressed against the cam grooves 3a and 3b by an urging member such as a spring (not shown) in the optical axis direction. As the lens rotates, the lens holding frames 1 and 2 can move smoothly in the optical axis direction without play.
[0015]
As is apparent from FIG. 1 , the stepping motor 4 that is pulse-driven receives the output from the first rotating shaft parallel to the optical axis direction by the reduction gear unit 5 having the second rotating shaft parallel to the optical axis direction. Decelerate to drive the output gear 5a. The output gear 5 a is interlocked with a gear portion 3 c provided on the cam ring 3. Reference numerals 9a and 9b denote guide members arranged in parallel with the optical axis, and the lens holding frames 1 and 2 are supported by the guide members 9a and 9b so as to be movable in the optical axis direction.
[0016]
FIG. 2 shows a developed view of the cam ring 3. Equilift portions 3a-1, 3a-2, 3b-1, 3b-2 are provided in the cam grooves 3a, 3b at the tele end and wide end positions, respectively. It has been. FIG. 3 is a schematic view in which the lens barrel body 10 incorporating the lens driving device having the above configuration is mounted on the optical device 11.
[0017]
Next, the operation will be described. In the zoom position according to the first embodiment, for example, the tele end and the wide end, the photo sensor provided in the apparatus main body (not shown) by the rib member 6 provided in the cam ring 3 by the rotation of the cam ring 3 is used. The initial position is detected by passing 7 and the lens movement amount is defined by the number of pulses from the initial position.
[0018]
Then, in consideration of backlash at the time of reversal caused by the reduction gear unit 5 or the like, the cam grooves 3a and 3b have equal lift portions 3a-1, 3a-2, 2b-1, 3b− at the tele end and wide end positions. because 2 is provided, reset position is driven (the initial detection position) from the telephoto end and the wide end of the pulse number + backlash amount above pulse number, to prevent less than go to the telephoto end and the wide end be able to. Further, the actual rotation angle of the cam ring 3 can be rotated to the outside, and the mechanical stopper and the friction mechanism at the tele end and the wide end are made unnecessary by the pulse control by the stepping motor 4.
[0019]
The rib member 6 for determining the reset is provided on the holding frame 1 that holds the variable power lens group 1a, the photo sensor 7 is provided at a predetermined position of the apparatus body, and the position of the rib member 6 in the optical axis direction is determined. Can be defined by the number of pulses from the initial detection position.
[0020]
Further, in the foregoing embodiment, the moving lens group 1a variable power lens, the movable lens group 2a may be an optical system comprising a Konpese over terpolymers.
[0021]
【The invention's effect】
As described above, according to the present invention, the lens holding frame is moved in the optical axis direction by using the cam as a guide by the pulse drive by the stepping motor, so that the lens position can be clearly defined, and the tele end This eliminates the need to provide a mechanical stopper at the wide end or a friction mechanism in the motor. As a result, the configuration can be simplified.
[0022]
Since the movement position of the lens holding frame is determined by the cam of the cam ring, complicated position control by the electronic cam is not required, and the mechanical mechanism and the control system can be simplified. Further, since the equal lift portions are provided at the tele end and the wide end of the cam ring, it is possible to prevent the tele end and the wide end from being insufficient due to the reverse backlash caused by gear loss.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a lens barrel according to an embodiment of the present invention.
2 is a development view of the cam ring in FIG. 1. FIG.
FIG. 3 is a schematic view in which a lens barrel is mounted on an optical device.
[Explanation of symbols]
1 Lens holding frame 2 Lens holding frame 3 Cam ring (cam means)
3a, 3b Cam groove (cam)
3a-1, 3a-2, 3b-1, 3b-2, etc. Lift cam 4 Stepping motor (drive means)
5 Reduction gear unit (reduction means)
6 Reset positioning member (position detection member)
7 Photosensor 10 Lens body 11 Optical device

Claims (2)

A first lens holding frame having a first interlocking piece and holding a first lens; a second lens holding frame having a second interlocking piece and holding a second lens;
A stepping motor having a first rotation axis parallel to the optical axis direction, a reduction gear having a second rotation axis parallel to the optical axis direction, and rotating to reduce the output of the stepping motor; A third axis of rotation parallel to the axial direction;
A cam ring that rotates in conjunction with the reduction gear, is parallel to the optical axes of the first and second lenses and is arranged radially outside the first and second lens holding frames, and a photosensor; Have
The cam ring is in contact with the first and second interlocking pieces on the outer peripheral surface thereof, and a cam groove for guiding the first and second lens holding frames in the optical axis direction in a predetermined relationship;
The cam ring protrudes in the radial direction, and includes a protrusion for detecting a reference position of rotation of the cam ring by the photosensor, and the number of pulses with the reference position detected by the photosensor as an initial position. A lens barrel that determines the amount of movement of the first and second lens holding frames.   An optical apparatus comprising the lens barrel according to claim 1.

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