JP3737266B2 - Lens barrel clutch mechanism - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a lens barrel of an interchangeable lens of a system camera, particularly a single lens reflex camera, and more particularly to a clutch mechanism of a lens barrel of an AF single lens reflex camera capable of manual distance ring adjustment.
[0002]
[Prior art]
In an AF single-lens reflex camera, a manual clutch mechanism is generally installed in the manual distance ring adjustment mechanism for the in-body motor-type and in-lens motor-type AF dedicated interchangeable lenses, and the drive motor interlocking system and the manual interlocking system are switched. . However, there have been problems in use due to the cumbersome switching operation and shooting timing. Also, when the drive motor is an ultrasonic motor, if the interlocking system is connected and the distance ring is turned by hand, the manual force is transmitted back to the motor side, and the rotor that maintains the pressure contact state of the ultrasonic motor There was a risk that the stator would slide and damage the characteristics.
[0003]
[Problems to be solved by the invention]
To eliminate these dissatisfactions and dangers of operability, the distance adjustment ring was manually adjusted even though the motor drive force was normally transmitted to the distance adjustment ring and the distance could be adjusted by the motor. In this case, a power transmission mechanism having a structure in which power from the manual side is not transmitted to the motor side has been desired.
[0004]
[Means for Solving the Problems]
In order to solve such a problem, the present invention provides a general lens barrel having a distance adjusting cylinder driven from a motor through a speed reduction mechanism and a manual adjusting cylinder interlocked with the distance adjusting cylinder from the motor to the distance adjusting cylinder except when the motor is driven. A part of the drive connection mechanism is always disconnected, and the distance adjustment cylinder can be manually adjusted without manual switching operation. The distance adjustment cylinder is connected only when the motor's rotational power is applied during automatic focus adjustment. In order to solve this problem, we installed a clutch mechanism that can transmit power.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
When the normal autofocus adjustment is inoperative, the power transmission system on the motor side and the distance adjustment cylinder side is cut off inside the clutch mechanism, and the distance adjustment cylinder is in a state where manual adjustment can be arbitrarily performed. When the rotational power from the motor is obtained, the coupling operation inside the clutch mechanism is performed by the rotational starting force, and the motor power can be transmitted to the distance adjusting cylinder. When the motor is stopped after being driven, the clutch mechanism is disconnected again and the transmission system between the motor and the distance adjusting cylinder is disconnected.
[0006]
【Example】
Hereinafter, the best embodiment of the present invention will be described with reference to the drawings.
[0007]
FIG. 1 is a schematic perspective view of the clutch mechanism of the present invention, and FIG. FIG. 3 is a cross-sectional view of a lens barrel on which the clutch mechanism of the present invention is mounted, and shows an embodiment of an in-lens motor type. FIG. 4 shows an example in which an encoder linked to the clutch mechanism of the present invention is installed. In the drawings, the same members are denoted by the same reference numerals. In the lens barrel cross-sectional view of FIG. 3, there are a front lens unit L1 and a rear lens unit L2 around the optical axis L0, and focus adjustment is possible by moving the front lens unit L1 linearly relative to the lens unit L2. An example of a simple lens barrel is shown.
[0008]
The front lens group L1 is held by the holding frame 1, the rear lens group L2 is held by the holding frame 2, and the helicoid part 5a of the distance adjusting cylinder 5 and the moving cylinder to which the holding frame 1 of the front lens group L1 is fixed. The four helicoid portions 4a are engaged with each other, and the movable cylinder 4 and the distance adjusting cylinder 5 can move linearly and integrally with the fixed cylinder 3. Further, the manual adjustment cylinder 6 is provided on the distance adjustment cylinder 5, and the key 5b of the distance adjustment cylinder 5 is fitted in the inner straight keyway 6a, so that the rotation of the manual adjustment cylinder 6 can be transmitted to the distance adjustment cylinder 5. In addition, due to the change in the relative angle between the movable cylinder 4 and the distance adjusting cylinder 5, the linear movement positions of the distance adjusting cylinder 5 and the front lens unit L1 of the holding frame 1 with respect to the movable cylinder 4 change, so that the focus adjustment of the main barrel can be performed. It is possible.
[0009]
On the other hand, when the motor shaft 12a is coupled to the clutch mechanism 11 and the input and output are coupled within the clutch mechanism 11, the power from the motor 12 is reduced from the pinion 9a on the clutch shaft 10 of the clutch mechanism. 9b, 9c, 9d is transmitted to the output pinion 9e, and the manual adjustment cylinder 6 and the distance adjustment cylinder 5 are integrally rotated by the internal gear 6b of the meshing manual adjustment cylinder 6, The distance adjusting cylinder 5 moves straight with respect to the moving cylinder 4 by the helicoid, and the front lens unit L1 changes the distance from the rear lens unit L2, thereby enabling an automatic focus adjustment operation.
[0010]
In the conventional structure, the motor shaft 12a and the clutch shaft 10 are coupled, and the motor power can be adjusted and rotated by the manual adjustment cylinder 6. However, for manual adjustment as it is, the motor shaft 12a rotates back to the motor 12. The manual adjustment cylinder 6 is very heavy to operate, and when the motor is an ultrasonic motor, the balance between the rotor and the stator that are in pressure contact may be lost due to inadvertent rotation. . In a general mechanism, a manual clutch is installed in the middle of the transmission mechanism from the motor to the manual adjustment cylinder during manual adjustment, and the connection is cut off by this clutch and then the distance is adjusted manually. Was avoiding. However, as described above, this was troublesome in operation.
[0011]
In the present invention, as shown in FIG. 3, a clutch mechanism 11 that automatically operates is provided between the motor 12 and the pinion 9a, which is the transmission mechanism, the reduction gear trains 9b, 9c, 9d, and the output pinion 9e. The solution is achieved by a method that does not require the switching operation of connection disconnection, and the structure and operation of the clutch mechanism 11 will be described in detail below.
[0012]
FIG. 1 is a schematic perspective view of the clutch mechanism 11. A motor pinion 13 is provided on the motor shaft 12 a and meshes with the motor transmission gear 14. An operating pin 15 is implanted upward in the motor transmission gear 14 and passes through an elongated hole 16a of a neutral gear 16 that is coaxially stacked. The motor transmission gear 14 is loosely fitted to the clutch shaft 10.
[0013]
On the neutral gear 16, left and right symmetrical locking levers (left) 17 and locking levers (right) 20 are arranged on the left and right with a ratchet 25 fixed to the clutch shaft 10 around the locking lever shaft 23. The spring 24 on the latch lever shaft 23 is hung on the spring latch pin (left) 18 and the spring latch pin (right) 21 of the latch lever 17, and the claw portions 17 a and 20 a of the left and right latch levers 17 are ratchet 25. The stopper pin (left) 19 and the stopper pin (right) 22 that are not engaged with each other are spread and urged to a position where they are in contact with each other. The distal end portions 17b and 20b of the left and right locking levers sandwich the operating pin 15 of the motor transmission gear 14 from the left and right. A pinion 9 a that transmits power to the reduction gear is fixed to the clutch shaft 10.
[0014]
As shown in FIG. 1, the neutral gear 16 meshes with the first speed increasing pinion 26, and the speed increasing gear 27 integrated therewith is transmitted to the second speed increasing pinion 28 to rotate the flywheel 29 fixed thereto at high speed. It is configured to operate inertially by a speed increasing mechanism including the flywheel.
[0015]
Next, the operation of the clutch mechanism will be described in detail with reference to FIG. 2. In the case of focus adjustment by the motor during autofocus operation, the motor rotation for adjustment operation is either left or right rotation, but both rotations are supported. Since this is necessary, the case of right rotation and the case of left rotation will be described separately. FIG. 2I is a plan view of the clutch mechanism, and the pinion 9a is omitted. Fig. 2 (II) is a clutch operation diagram at the time of starting rotation of the motor left and right, Fig. 2 (III) is an operation diagram of the power transmission state with the motor rotating continuously, and Fig. 2 (IV) is an operation diagram of the clutch release when the motor is stopped. .
[0016]
In the state where the motor is not operated, the clutch shaft 10 can freely rotate with respect to the motor transmission gear 14 as shown in FIG. 2 (I), and the neutral gear 16 is also loosely fitted with respect to the clutch shaft 10, Since the claw portions 17a and 20a of the left and right locking levers are slightly spaced from the shaft ratchet 25, the clutch shaft 10 is in a state of being freely rotatable without being constrained. For this reason, even if manual force is applied to the manual adjustment cylinder 6 to transmit it to the motor side in the reverse direction via the pinion 9a, the reduction gear trains 9b, 9c, 9d, and the output pinion 9e, which are interlocking gear trains, the clutch from the pinion 9a Since the shaft 10 is simply idled and is not transmitted to the motor side, manual distance adjustment is free and light operation is possible.
[0017]
Next, when considering the case where the motor rotates as in the case of autofocus operation, when the motor pinion 13 starts to rotate clockwise as shown in FIG. 2A, the meshed motor transmission gear 14 moves to the left. Start spinning. In accordance with this, the operating pin 15 implanted in the motor electric gear 14 also rotates together, and the tip 20b of the locking lever (right) 20 on the left side of this pin is pushed to rotate the neutral gear 16 as well. However, an inertia mechanism from the first speed increasing pinion 26 to the flywheel 29 is connected to the neutral gear 16, and there is resistance to the starting force, so that it does not start immediately. For this reason, against the biasing force of the spring 24, the locking lever (right) 20 falls down as the operating pin 15 moves to the left about the locking lever shaft 23, and the locking lever (right) ) 20 claw portions 20 a mesh with each other, and the locking lever (right) 20 is coupled to the ratchet 25. As shown in the figure, the operating pin 15 is coupled when it is rotated counterclockwise by the angle R1.
[0018]
When the rotation is further continued, as shown in A of FIG. 2 (III), the locking lever (right) 20 is tilted in accordance with the left rotation of the motor transmission gear 14, and the neutral gear remains connected to the ratchet 25 at the center. 16 is rotated together with the inertia mechanism from the first speed increasing pinion 26 to the flywheel 29, so that the manual adjustment cylinder 6 is moved from the pinion of the clutch shaft 10 integral with the ratchet 25 through the reduction gear trains 9b, 9c, 9d and the output pinion 9e. The focus can be adjusted by changing the distance adjusting cylinder 5 which can be rotated by the motor 12.
[0019]
Next, when the focal point is reached from the right rotation of the motor and the motor is stopped, the state is shown in FIG. 2 (IV). Since the motor is completely stopped in FIG. 2 (IV), the operating pin 15 of the motor transmission gear 14 is shown. However, because of the inertial mechanism including the flywheel 29, the neutral gear 16 receives the inertial force and only the neutral gear 16 does not stop abruptly, and the left rotation is overrun by a small angle Wl. On the other hand, the locking lever (right) 20 is returned in accordance with the repulsive force of the spring 24. In this process, the claw portion 20a of the locking lever (right) 20 is separated from the ratchet 25, and is released from the clutch disengagement state shown in FIG.
[0020]
Similarly, in the case of the counterclockwise rotation of the motor, as shown in FIG. 2B, when the operating pin 15 moves at the rotation angle Rr with respect to the right rotation start of the motor transmission gear 14, the locking lever (left) 17 When the claw portion 17a is engaged with the ratchet 25 and the clutch is coupled, the first speed increasing pinion 26, the speed increasing gear 27, the second speed increasing pinion 28, and the flywheel 29 of the inertia mechanism as shown in FIG. Rotating together, the left rotational power of the motor 12 can be transmitted to the manual adjustment cylinder 6 as well as the right rotation of the motor. When the motor is stopped from this motor left rotation driving state, the neutral gear 16 overruns the Wr angle from the stop position of the operating pin 15 in the same manner as in the case of the stop from the motor right rotation described above. (Left) 17 releases the coupling with the ratchet 25 and returns to the state of FIG. As described above, the clutch is engaged and can be driven for focus adjustment each time for normal motor control operation of normal rotation and reverse rotation of the motor, and the clutch is disengaged when the motor is stopped. It can be seen that manual adjustment can be easily performed.
[0021]
In order to adjust the focus, it is necessary to detect the amount of movement of the distance adjusting cylinder 5 of the lens barrel by rotational driving of the motor and control it according to the focus error. In general, the motor is used to increase the resolution of the amount of movement of the distance adjusting cylinder. A slit disk is installed in the terminal through a speed increasing mechanism that is linked to the drive mechanism, and an encoder device that reads the number of slits of the slit disk that rotates at high speed with a photo interrupter is installed at a position that can be linked to the motor. FIG. 4 shows an example in which an encoder device having the same structure is installed in the lens barrel. In this mechanism, a speed increasing mechanism constituted by a first speed increasing pinion 26, a speed increasing gear 27, and a second speed increasing pinion 28 is connected to the neutral gear 16, and the second speed increasing pinion 28 is synchronized with the rotation of the neutral gear 16. The slit disk 30 having the same axis is rotated at high speed, and the slit 30a is read by the photo interrupter 31. This method is effective for the clutch operation due to the inertia effect because the encoder device is provided with the speed increasing mechanism. Since the rotation of the clutch operation at the time of starting the motor is not transmitted to the slit disk 30, the distance adjusting cylinder 5 is moved. On the other hand, there is no erroneous measurement.
[0022]
【The invention's effect】
As described above, according to the configuration of the present invention, it is possible to provide an inexpensive and high-quality AF lens barrel that can be always adjusted without providing any special switching means in manual adjustment of the AF lens.
[Brief description of the drawings]
FIG. 1 is a schematic perspective view of an automatic clutch mechanism of an embodiment.
FIG. 2 is an operation explanatory view of the automatic clutch mechanism of the embodiment.
FIG. 3 is a cross-sectional view of a lens barrel of the embodiment.
FIG. 4 is a diagram in which an encoder is installed in the embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Front lens group L1 holding frame 2 Rear lens group L2 holding frame 3 Fixed cylinder 4 Moving cylinder 5 Distance adjusting cylinder 6 Manual adjusting cylinder 10 Clutch shaft 11 Clutch mechanism 12 Motor 13 Motor pinion 14 Motor transmission gear 15 Actuation pin 16 Neutral gear 17 Locking lever (left)
18 Spring hook pin (left)
19 Stopper pin (left)
20 Locking lever (right)
21 Spring hook pin (right)
22 Stopper pin (right)
23 Locking lever shaft 24 Spring 25 Ratchet 26 First speed increasing pinion 27 Speed increasing gear 28 Second speed increasing pinion 29 Flywheel 30 Slit disk 31 Photo interrupter

Claims (3)

The distance adjustment cylinder driven by a motor, a lens barrel for focus adjustment, usually have been cut off in the middle of the power transmission mechanism to said distance adjusting cylinder from said motor, manual adjustment of the distance adjusting cylinder possible, the power transmission mechanism only when the driving force is applied to the motor from the motor to the distance adjusting cylinder is connected, in a lens barrel having a possible automatic focusing function by the motor, the motor-side A motor transmission gear connected to the center and a neutral gear installed as a pair of symmetrical locking levers biased toward the center outside are coaxially installed, and are coaxial with the motor transmission gear and the neutral gear. In general, the shaft that fixes the pinion and the ratchet connected to the distance adjustment cylinder side is free, and the distance adjustment cylinder can be manually rotated. When any of the power is transmitted, the motor transmission gear moves toward the center of the locking lever claw of the neutral gear and meshes with the ratchet, so that the motor side power transmission member and the distance adjustment cylinder side power transmission member are A lens barrel clutch mechanism characterized by being coupled to enable driving of a distance adjusting cylinder by a motor . A speed increasing mechanism having a flywheel effect is connected to the neutral gear, and the engagement of the locking lever with the ratchet at the start of motor rotation and the release operation of the ratchet engagement of the locking lever at the stop of motor rotation are ensured. The lens barrel clutch mechanism according to claim 1, wherein the lens barrel clutch mechanism is raised. In conjunction with the motor drive mechanism, an encoder device for controlling the amount of movement of the distance adjusting cylinder of the lens barrel by reading the number of slits of rotation of the slit disk of the terminal through the speed increasing mechanism is connected to the neutral gear. The lens barrel clutch mechanism according to claim 1.

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