JPH01167715A - Focusing operation switching mechanism - Google Patents

Abstract

PURPOSE:To eliminate the need for a clutch member, etc., which performs connection and disconnection between the rotor of an ultrasonic motor and a lens driving shaft, to prevent a cost from being higher and to make a structure excellent in terms of space by performing the switching of AF and manual focusing with a differential mechanism with a screw. CONSTITUTION:As to the rotation of the driving shaft at the time of AF, said shaft moves in an optical axis direction with rotating since a manual operation member 14 where the coaxial screw part 15a is screwed is in a fixed state. Therefore, a focusing lens frame 1 coaxially integrated also moves and a focusing lens group L1 is moved to a specified focusing position on the optical axis. Since the rotor 21 of the ultrasonic motor USM is in an immobile fixed state at the time of manual focusing, a gear 26 for automatic focusing can not rotate and the screw part 15a which is screwed with the internal screw of the rotating manual operation member 14 is moved in the optical axis direction, so that the driving shaft moves in the optical axis direction without rotating and performs focusing actions. Namely AF and manual focusing can be switched with the differential mechanism with the screw. Thus, the structure can be simplified and the costdown can be attained.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a focusing operation switching mechanism, and more specifically, to a switching mechanism for a focusing operation, specifically, a focusing lens in a camera, etc., which moves to a focusing position automatically or manually. This invention relates to a switching mechanism for focusing operations.

[Prior Art] As is well known, in recent years, focusing devices in cameras and the like have been performing autofocus (hereinafter referred to as AF) operations in which a focusing lens such as a photographing lens is moved to a focusing position by a motor, and this is performed manually. Manual operation can be selected by switching, and in recent years, models using an ultrasonic motor as the AF motor have been highly praised. The switching mechanism for this focusing operation has the following features: (1) In Hirao, the focusing lens is moved by the driving force of the AF motor, and a clutch mechanism is provided in this driving force transmission mechanism to allow manual operation. Sometimes the same clutch mechanism cuts off the transmission of driving force from the AF motor to the focusing lens, allowing manual focusing operation. (2) In the case of using an ultrasonic motor as the AFF motor, A mechanism is provided to weaken the compression force of the spring that presses the stator and rotor together, and during manual operation, this mechanism is activated so that the focusing lens can be manually driven (3) JP-A-59-101608 As disclosed in the official gazette, electric motors using ultrasonic motors
It has been proposed that a control means for generating a standing oscillation wave is provided in the mechanical energy conversion, and manual drive can be performed by this control means during manual operation.

[Problems to be solved by the invention] However, in the above-mentioned conventional technical means, (1)
In the above-mentioned item (1), which uses a clutch mechanism to switch from AF to manual, (a) rattling occurs due to the clutch, and the operating member rattles during manual operation, giving a sense of discomfort.

(ii) In the method described in (2) above, which weakens the compression spring of the ultrasonic motor, the resonant frequency of the ultrasonic motor (as a general rule, one motor resonates There is a risk that the frequency may be shifted.

(in) If the ultrasonic motor is subjected to standing wave vibration during manual operation as described in item (3) above to lighten the rotation of the rotor and perform manual operation, current must be kept flowing even during manual operation. , battery consumption increases.

There is a drawback. In particular, in a camera that uses an ultrasonic motor as an AFF motor, further has a zoom optical system, and has a lens optical system in which a focusing lens, which is a focusing optical system, constitutes a part of the zoom optical system. teeth,
The above-mentioned conventional technical means cannot be applied to the focusing operation switching mechanism because the structure becomes complicated and the cost increases.

Therefore, an object of the present invention is to provide a focusing operation switching mechanism that skillfully uses the threaded shaft of an AF ultrasonic motor and does not have the drawbacks of the conventional ones.

[Means and effects for solving the problem] The focusing operation switching mechanism according to the present invention is arranged in a lens barrel, and includes an ultrasonic motor that drives a focusing lens, and an ultrasonic motor that drives a focusing lens, a drive shaft which is arranged and has an autofocus gear driven by the rotor of the ultrasonic motor and a manually driven screw portion; and a focusing lens frame that moves together with the drive shaft in the optical axis direction. and is screwed into the threaded portion of the drive shaft, and is made immovable when the lens frame is driven by the ultrasonic motor, converting the amount of rotation of the drive shaft into the amount of movement in the optical axis direction, and moving the lens frame. When manually driven, the rotor of the ultrasonic motor is made immobile and rotatable, and is characterized by comprising a manual operation member that moves the screwed drive shaft forward and backward in the direction of the optical axis. Therefore, both during AF operation and manual focusing operation,
The focusing lens is driven by the same drive shaft.

[Example] The present invention will be described below with reference to an illustrated example. The focusing operation switching mechanism of this embodiment incorporates an ultrasonic motor for AF, and the focusing lens group constitutes a part of the zoom optical system. The lens is disposed within a lens barrel having a lens optical system that moves to perform a zoom operation.

' As shown in Fig. 1.2, this focusing operation switching mechanism consists of a focusing lens frame 1 that supports a focusing lens group L1, whose base is fixed to a fixed frame 2, and is parallel to the lens optical axis. It is arranged to move back and forth in the optical axis direction guided by a focusing guide shaft 3, and the zoom lens frame 4 holding the zoom lens group L2 has its base end attached to the fixed frame 2. A zoom guide shaft 5 fixedly arranged parallel to the lens optical axis
It is designed to move in the optical axis direction.

It should be noted that FIG. 1 is a plan view showing the focusing operation switching mechanism.

A cam guide shaft 6 whose base end is fixed to the fixed frame 2 and is arranged parallel to the optical axis is provided near the zoom guide shaft 5. A zoom cam cylinder 7 is rotatably fitted. This cam cylinder 7 has a zoom gear 7 formed on its outer periphery near its base.
d is rotated around the guide shaft 6 by being driven by a zoom operation ring (not shown).

As shown in FIG. 4(A), a linear cam groove 7a extending perpendicularly to the guide shaft 6 is bored at a position near the fixed frame 2 on the outer peripheral surface of the cam cylinder 7. Same cam groove 7
As shown in FIG. 1, a regulating pin 10 fixed to an angle member 9 having an angular cross section fixed to the fixed frame 2 with a screw 8 is fitted into the hole a, and the optical axis of the zoom cam barrel 7 is adjusted. In addition to restricting movement in the direction, the range of rotation in the circumferential direction is also restricted.

Zooming cam grooves 7b and 7C having shapes shown in FIGS. 4(B) and 4(C) are formed in the outer circumferential surface of this cam cylinder 7, respectively. The zoom cam groove 7C is formed as a linear inclined groove, and as shown in FIG. 1, a drive pin 11 fixed to the zoom lens frame 4 is fitted into the cam groove 7C. . In addition, the zoom cam groove 7
b is formed by a partially arcuate cam groove, and the cam groove 7
A driving pin 12 fixedly attached to a connecting member 13 for moving the focusing lens frame 1 is fitted into the inside b. The connecting member 13 is disposed so as to fit into the focusing guide shaft 3 and move back and forth in the optical axis direction, and the driving pin 12 is installed at its rear end. A circular opening 13b is formed in the front end 13a of the connecting member 13, and a manual operation member 14 is rotatably disposed in the opening 13b with a portion of the manual operation member 14 fitted therein. .

This manual operation member 14 has a drive shaft 15 in the center which will be described later.
It is composed of a gear with a female thread carved thereon that is screwed into the threaded portion 15a of
It is rotatably attached to the connecting member 13, and is prevented from coming off from the front end portion 13a by a retaining ring 16 fitted to the rear outer periphery. The gear of this manual operation member 14 meshes with the internal teeth of a distance ring 17 (see FIG. 2) which is rotated when performing a manual focusing operation. Therefore, when the distance ring 17 is rotated, the manual operation member 14 rotates around the drive shaft 15.

On the other hand, as shown in FIG. 2, a step 1a is formed on the outer peripheral surface of the focusing lens frame 1 near the front, and the step 1a is screwed to the front end of the lens frame 1. Lens holding frame 1
An ultrasonic motor USM is disposed on the outer peripheral surface of the lens frame 1 between the outer flange 8 and the outer flange 8 .

That is, this ultrasonic motor USM has a well-known configuration, and includes a ring-shaped bearing 19 disposed in contact with the stepped portion 1a, and a bearing ball 20 connected to the bearing 19 to connect the lens frame 1 to the ring-shaped bearing 19. a ring-shaped rotor 21 rotatably disposed around the rotor 21; a stator 22 that is in pressure contact with the rotor 21 and generates a traveling wave that rotates the rotor 21;
A piezoelectric element 23 that is fixed to the stator 22 and generates a traveling wave in the stator 22;
a vibration isolating member 24 made of felt or the like, which is in contact with the vibration isolating member 24; and a compression spring which is stretched between the member 24 and the flange of the lens holding frame 18 and presses the stator 22 against the rotor 21. It consists of 25. A gear 21a is provided on the outer peripheral surface of the rotor 21 of this ultrasonic motor USM.
is formed, and an autofocus gear 26 is meshed with this gear 21a.

The autofocus gear 26 is fixed to the tip of the drive shaft 15, as shown in FIG. The drive shaft 15 is arranged parallel to the lens optical axis, has the autofocus gear 26 fixed to its tip, and has a screw portion near the front into which the female thread of the manual operation member 14 is screwed. 15a is formed. The rear small-diameter shaft portion 15b rotatably passes through the focusing lens frame 1, and is prevented from coming off by a retaining ring 27 fitted to the flange 15c and the rear end of the focusing lens frame 1. 1
is integrated into.

Further, a distance display mechanism is disposed around the drive shaft 15 and operates in conjunction with the focusing lens frame 1 during a focusing operation. This distance display mechanism is loosely fitted to the outer peripheral surface of the drive shaft 15, and includes a driving gear 28a, a regulating long groove 28b, and a driving cam, which are carved near the front of the outer peripheral surface. A driving cylinder 28 having a groove 28c, a regulating pin 29 and a driving pin 30 that fit into the long groove 28b and the cam groove 28c, respectively, a connecting gear 31 that meshes with the driving gear 28a, and a rotating shaft that is rotated by the connecting gear 31. and a distance display disk 32.

As shown in FIG. 5(A), the regulating long groove 28b is formed of a straight groove bored in a direction perpendicular to the optical axis.
The movement in the optical axis direction and the rotation range in the circumferential direction are restricted by fitting the restriction pin 29 fixedly planted in the connection member 13. Also, the driving cam groove 28c is shown in Fig. 5 CB.
), it is formed by a straight inclined groove, and the first
As shown in the figure, the driving pin 30 fixed to the L-shaped angle member 34 fixed to the focusing lens frame 1 with a screw 33 is inserted, and the pin 30 is inserted into the focusing lens frame 1 together with the focusing lens frame 1. By moving the drive cylinder 28 in the axial direction, the drive shaft 15
It serves to rotate around the.

Also, a connecting gear 31 meshing with the driving gear 28a
is rotatably disposed on the outer surface of a support member 35 integrally attached to the fixed frame 2 by a support shaft 36, and the connecting gear 31 is integrally formed with the distance display disk 32. Gear 32a is engaged. This distance display disk 32 is also rotatably attached to the support member 35 by a support shaft 37, and the distance to the subject is marked as a scale on the circumferential surface of the disk 32, which is displayed on the outer surface of the camera. It is designed to be indicated by an indicator 38.

Next, the operations of the focusing operation switching mechanism of this embodiment configured as described above will be explained in order: (I) during AF operation, (n) during manual focusing operation, and (■) during zoom operation. I will explain later.

(I) During AF operation In this case, the distance ring 17 is restrained in a non-rotatable state by switching the AF-manual switching member (not shown) to the AF side. Therefore, the manual operation member 14 also remains stationary. In this state, when a predetermined amount of rotation signal based on the AP multiplied signal is applied to the ultrasonic motor USM, the rotor 2
1 rotates.

When this rotates, the autofocus gear 26 that meshes with the rotor 21 rotates, causing the drive shaft 1 to rotate.
5 rotates. The rotation of this drive shaft 15 is caused by the coaxial threaded portion 1
Since the manual operation member 14 screwed into the drive shaft 15 is in a fixed state, the drive shaft 15 moves in the optical axis direction while rotating.

Therefore, the focusing lens frame 1 integrated with the coaxial 15 also moves, thereby moving the focusing lens group to a focusing position on a predetermined optical axis.

Furthermore, when the focusing lens frame 1 moves in the optical axis direction, the drive cylinder 28 is moved by the drive bottle 30 and the cam groove 28c.
rotates around the drive shaft 15, so the drive gear 28a
, connection gear 31. The distance display disc 32 rotates via the gear 32a, and the distance focused by this autofocus operation is displayed.

(II) Manual focusing operation During this operation, the AF-manual switching member (not shown) is switched to the manual side.

Then, the restraint of the distance ring 17 is released, and the circumferential ring 17 can be rotated manually. Therefore, when the distance ring 17 is manually rotated to perform a focusing operation, the manual operation member 14 rotates around the threaded portion 15a of the drive shaft 15 due to the rotation of the distance ring 17. At this time, the ultrasonic motor USM Unlike the rotor of a normal electromagnetic motor, the rotor 21 is in an immovable fixed state, so the autofocus gear 26 cannot rotate, and therefore the rotating manual operation member 1 cannot rotate.
The threaded portion 15a screwed into the female screw No. 4 is fed in the optical axis direction, thereby causing the drive shaft 15 to move in the optical axis direction without rotating. Therefore, since the focusing lens frame 1 also moves, the focusing operation is performed by the focusing lens group L1.

Furthermore, in this case as well, the distance display mechanism operates in conjunction with the movement of the focusing lens frame 1 in the same manner as during AF operation, so that the focusing distance is displayed.

In this way, in this embodiment, the connection between the ultrasonic motor USM and the drive shaft driven by the ultrasonic motor USM is determined during AF operation and manual operation, while the focusing lens group is moved by the ultrasonic motor USM. .

It is possible to switch between AF and manual focus without providing a clutch mechanism or the like for disengagement, that is, by using a screw differential mechanism.

(III) During zoom operation During this zoom operation, a zoom operation ring (not shown) is rotated. When this is rotated, the zoom cam cylinder 7 is rotated around the guide shaft 6 via the zoom gear 7d.

Then, the drive pin 11 moves in the optical axis direction due to the rotation of the zoom cam groove 7c, which is an inclined groove, so the zoom lens frame 4 moves along the guide shaft 5, and the zoom lens group L2 is moved to a wide angle position. ) toward the telephoto (telephoto) side, or toward the wide side when the telephoto position is visible.

At the same time, the drive pin 12 moves the connecting member 13 in the optical axis direction along the guide shaft 3 due to the rotation of the zoom cam groove 7b, which is a partially arcuate groove. The manual operation member 14 that is integrally attached to the drive shaft 15 and the drive shaft 15 that has a threaded portion 15a screwed into the member 14 move together in the optical axis direction, and the drive shaft 15 moves along the optical axis. A focusing lens frame 1 integrated in the direction is moved along a guide shaft 3. Therefore, the focusing lens group L1 moves toward the telephoto side when the wide angle is detected, or moves toward the wide side when the telephoto angle is not detected, and performs a magnification change operation in cooperation with the zoom lens group L2.

Figure 3 shows the movement locus of the magnification changing operation of both lens groups, L, mentioned above.The focusing lens group L1 performs the focusing operation between close range and ψ, and both lenses The zooming operation is performed between the groups , , L, and the telephoto T side when the wide W is known.

Note that during this zoom operation, in the distance display mechanism, the focusing lens frame 1 and the connecting member 13 move together, so the drive barrel 28 does not rotate, and therefore, the distance display mechanism does not operate.

[Effects of the Invention] As described above, according to the present invention, the screw shaft is rotated by the ultrasonic motor to move the focusing lens group, and switching between AF and manual focus is performed by using the operating member (distance ring). We have provided a screw-based differential mechanism that prevents the rotor of the ultrasonic motor and the drive screw shaft from connecting or disconnecting by fixing and releasing.1) A clutch member, etc. that quickly disconnects the rotor of the ultrasonic motor and the lens drive shaft. Therefore, the cost is not high and it is advantageous in terms of space.

2) There is no rattling or backlash caused by the clutch mechanism, there is no strange feeling in operation, and there are fewer errors.

3) Since no clutch mechanism is used, troubles such as half-clutching do not occur, and reliability is increased.

4) Coarse adjustment can be performed by AF operation, and fine adjustment can be performed by manual operation.

It is possible to provide a focusing operation switching mechanism that exhibits remarkable effects such as these and eliminates the conventional problems.

[Brief explanation of the drawing]

1 and 2 are cross-sectional views of a focusing operation switching mechanism showing an embodiment of the present invention, FIG. 1 is a planar development of the switching mechanism, and FIG. Figures 4 (A) to (C) are plan views showing the shapes of the zoom cam grooves, respectively; Figures 5 (A) and (B) 2A and 2B are plan views respectively showing drive cam grooves of the distance display mechanism. USM......Ultrasonic motor...
......Focusing lens frame 14...
...Manual operation member 15... Drive shaft 15a... Threaded portion 21... Rotor 26.・・・・・・・・・・・・Focus gal 1
Figure 2 Figure Easy 3 Capture 4 (A) (B) %5 (A) Figure (C) Figure (B)

Claims (1)

[Claims] An ultrasonic motor disposed within a lens barrel and driving a focusing lens; and an autofocus disposed parallel to the optical axis of the lens and driven by the rotor of the ultrasonic motor. a driving shaft having a gear and a threaded portion that is manually driven; a focusing lens frame that moves integrally with the driving shaft in the optical axis direction; and a focusing lens frame that is threadedly engaged with the threaded portion of the driving shaft; When the lens frame is driven by the ultrasonic motor, the rotor of the ultrasonic motor is kept stationary and the rotation amount of the drive shaft is converted into the amount of movement in the optical axis direction, and when the lens frame is manually driven, the rotor of the ultrasonic motor is kept stationary. A focusing operation switching mechanism comprising: a manual operating member which is rotatable and moves the screwed drive shaft forward and backward in the optical axis direction;