JPH11202181A - Clutch mechanism for lens barrel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an inexpensive high-quality AF lens barrel which can be always adjusted by providing a clutch mechanism which is actuated to transmit the rotational power of a motor to a distance adjusting barrel and not to transmit reverse power by manual operation for adjusting a distance to the motor. SOLUTION: This automatically acting clutch mechanism 11 is provided between the motor 12 and a clutch pinion 9a, a reduction gear train 9b to 9d and an output pinion 9e which are a transmission mechanism. The power is transmitted to the output pinion 9e through the gear train 9b to 9d from the clutch pinion 9a existing on the output shaft 10 of the mechanism 11 so as to turn a manual adjusting barrel 6 by the internal gear 6b of the barrel 6 meshed with the pinion 9e, whereby automatic focusing operation is performed. Thus, the power for the focusing of a lens is faithfully transmitted to the distance adjusting barrel 5 whether the motor 12 is normally rotated or reversely rotated at the time of driving the motor 12. On the other hand, the manual power at the time of manual adjustment is interrupted so as not to be transmitted to the motor 12 side and the light manual adjustment is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a system camera, and more particularly to a lens barrel of an interchangeable lens of 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]

2. Description of the Related Art In an AF single-lens reflex camera, a manual clutch mechanism is installed in a manual distance ring adjusting mechanism of an in-body motor type and an in-lens motor type AF exclusive interchangeable lens, and a method of switching between an interlocking system of a driving motor and a manual interlocking system. Is common. However, at the time of use, there is a problem due to the inconvenience of the switching operation and the timing of shooting. 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 and stator maintain the pressure contact state of the ultrasonic motor. However, there was a danger that the sliding would impair the characteristics.

[0003]

In order to eliminate the dissatisfaction and danger of the operability, when the motor is driven, the motor driving force is transmitted to the distance adjusting ring, and the distance can be adjusted by the motor. However, when the distance adjustment ring is manually adjusted, 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]

SUMMARY OF THE INVENTION In order to solve such a problem, the present invention relates to a general lens barrel having a manual adjustment cylinder in which a driving cylinder driven from a motor through a speed reduction mechanism is interlocked with a distance adjustment cylinder. The solution was achieved by installing an operating clutch mechanism that transmits the rotational power of the motor to the distance adjustment cylinder and does not transmit the manual reverse power to the motor for part of the drive connection mechanism to the drive cylinder.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Normally, the driving side and the driven side are locked in a clutch mechanism. During an automatic focusing operation, a manual adjusting cylinder and a distance adjusting cylinder receive rotation power from a motor to automatically focus. A connection system has been established so that the adjustment operation can be performed. On the other hand, when the manual operation power is applied to the adjusting cylinder, the manual force acts to release the lock in the clutch mechanism, and disconnects the coupling system. It does not transmit power.

Hereinafter, the best embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic perspective view of a clutch mechanism according to the present invention, and FIG. 2 is an explanatory view of its operation. FIG. 3 is a sectional view of a lens barrel equipped with the clutch mechanism of the present invention, showing an embodiment of a motor-in-lens type. In the drawings, the same members are denoted by the same reference numerals. In the sectional view of the lens barrel in FIG. 3, there are a front lens unit L1 and a rear lens unit L2 around the optical axis L0, and the focus can be adjusted by moving the front lens unit L1 straight with respect to the lens unit L2. 2 shows an example of a simple lens barrel.

The front lens unit L1 is held by a holding frame 1, and the rear lens unit L2 is held by a holding frame 2.
The helicoid part 5a of the distance adjusting cylinder 5 to which the holding frame 1 is fixed and the helicoid part 4a of the moving cylinder 4 are engaged with each other. You can do it. In addition, the distance adjusting cylinder 5
There is a manual adjustment cylinder 6 on the top, and the key 5b of the distance adjustment cylinder 5 is fitted in the inner straight keyway 6a.
Can be transmitted to the distance adjusting cylinder 5, and a change in the relative angle between the moving cylinder 4 and the distance adjusting cylinder 5 causes the linear position of the distance adjusting cylinder 5 with respect to the moving cylinder 4 and the front lens unit L 1 of the holding frame 1 to move. Is changed, and the focus of the lens barrel can be adjusted.

On the other hand, the power from the motor 12 is
2a is coupled to the clutch mechanism 11 and is transmitted from the clutch pinion 9a on the output shaft 10 of the clutch mechanism 11 through the reduction gear trains 9b, 9c, 9d to the output pinion 9e, and the inside of the engaged manual adjustment cylinder 6 The manual adjustment cylinder 6 is rotated by the tooth gear 6b to enable an automatic focusing operation.

In the conventional structure, the motor shaft 12a and the output shaft 1
0 is connected, and the motor power can adjust and rotate the manual adjustment cylinder 6, but to perform the manual adjustment as it is, the motor power is rotated back to the motor 12, and the manual adjustment cylinder 6 is rotated. The operation was very heavy. With 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 to disconnect the connection, and this clutch is used to disconnect the connection and then manually adjust the distance. Was avoiding. However, as described above, this was troublesome in operation. In the present invention, as shown in FIG. 3, a clutch mechanism 11 which operates automatically is provided between the motor 12 and the clutch pinion 9a which is a transmission mechanism, the reduction gear trains 9b, 9c, 9d, and the output pinion 9e. A method that does not require a switching operation of connection disconnection is adopted to solve the problem, and the structure and operation of the clutch mechanism 11 will be described in detail below.

FIG. 1 is a schematic perspective view of the clutch mechanism 11, in which a motor shaft 12a has a motor pinion 13 which meshes with a clutch gear 14. Clutch gear 14
Has a cam 17 which is rotatable around a clutch shaft 18 and has a slope 17a and a slope 17d, and a projection 17e serving as a spring receiving and pin-implanted portion has a vertical center. It has a left-right symmetrical shape provided with an inclined surface 17b, an inclined surface 17c, and a projection 17f with respect to the line. Cam 1
Rollers 15 a, 15 b, 15 c, respectively in four wedge-shaped spaces formed with respect to the four inclined surfaces 17 a, 17 b, 17 c, 17 d of No. 7 and the inner cylindrical surface 14 a of the clutch gear 14.
15d, and the inclined surfaces 17a, 17b, 17c, and 1c of the cam 17 by springs 16a, 16b, 16c, and 16d each having one end applied to the projections 17e and 17f of the cam 17.
Pressure is applied between each of the rollers 7d and the clutch gear inner cylindrical surface 14a so as to push each roller.

A friction disk 21 and a cruciform disk 22 to which a clutch pinion 9a is fixed are provided so as to overlap with the clutch gear 14 so as to cover the inside of the cylinder of the clutch gear from above. Length 22b and 22 of cruciform board 22
Actuation pins 19a and 19b are respectively implanted toward the inside of the clutch in d.
1a and 21b, the operating pin 19a is in the gap between the rollers 15a and 15b, and the operating pin 19b is in the gap between the rollers 15c.
And a roller 15d.

Cam pins 20a and 20b are implanted in the projections 17e and 17f of the cam 17 in the upward direction. The cam pins 20a pass through through holes 21d of the upper friction plate 21 and project from the cruciform plate 22 in the lateral direction. The cam pin 20 is attached to the U-shaped catch 22a.
“b” passes through a through hole 21 c of the friction disk 21 and is held by a U-shaped catch 22 c of the cross-shaped disk 22. In addition, cruciform board 2
The shape of the two U-shaped catches 22a and 22c is
Although a play is provided for the rotational movement of the a and 20b, the through holes 21d and 21c are fitted to the friction plate 21, and the through hole 21e at the center is loosely fitted to the clutch shaft 18. Therefore, it rotates integrally with the cam 17. A braking plate 23 comes into contact with the friction plate 21 from the outside, and the rotation of the friction plate 21 is constantly braked by friction.

Next, the operation of the clutch mechanism 11 will be described in detail with reference to FIG. 2. In the case of the focus adjustment by the motor during the automatic focus operation, the rotation of the motor for the adjustment is either left or right. Since it is necessary to correspond, the case of the left rotation and the case of the right rotation will be described separately. FIG. 2 (I) is a plan view of the clutch mechanism, showing the motor pinion 13 and the friction plate 21 and the brake plate 2.
3 is omitted.

Now, considering the case where the motor rotates clockwise, the clutch gear 14 meshing with the motor pinion 13 is moved counterclockwise (C) as shown by the arrow (II) in FIG.
CW), the roller 15a is pressed by the spring 16a between the inclined surface 17a of the cam 17 and the inner cylindrical surface 14a of the clutch gear 14, so that the roller 15a rotates in accordance with the left rotation of the inner cylindrical surface. The inclined surface 17a of the cam 17 is pushed, and the clutch gear 14 and the cam 17 try to move integrally. However, since a friction plate 21 not shown in FIG. 2 is connected to the cam 17 and a force for preventing rotation is applied to the cam 17 by the brake plate 23, the roller 15a moves in accordance with the left movement of the inner cylindrical surface 14a. , Rolling in the direction of the arrow,
7 is slightly climbed on the inclined surface 17a, and the clutch gear 1
While the roller 15a bites more and more into the locked state between the inner cylindrical surface 14a of No. 4 and the inclined surface 17a of the cam 17,
The rotation of the roller 15 b in the direction of the arrow with respect to the inclined surface 17 b of the cam 17 acts in a direction loosening the wedge shape formed by the inner cylindrical surface 14 a and the inclined surface 17 b of the cam 17.
It does not hinder the counterclockwise rotation of.

Since the clutch gear 14 is locked by the cam 17 via the roller 15a, the clutch gear 14 is rotated counterclockwise as a unit while receiving a small amount of braking on the friction disk 21. The operation is performed during the rotation angle Rl.
The power is transmitted to the cruciform plate 22, and the clutch pinion 9a is rotated to transmit the right rotation power of the motor. Since this mechanism has a symmetrical structure about the axis, the same operation is performed at a symmetrical position across the axis, so that the description of the other operation is omitted, but the inclined surface 17a of the cam 17 is located at the diagonal position 17c. ,
The roller 15a is 15c, and the operating pin 19a is 19b and performs the same operation at each symmetrical position to transmit the motor power to the cruciform plate 22 and the clutch pinion 9a.

Next, considering the case where the motor rotates leftward, the clutch gear 14 rotates clockwise (CW) in the direction of the arrow as shown in FIG.
The roller 15b is moved to the right side of the cam 17 by the rightward movement of 4a.
7b is to be rolled in the direction of the arrow, the clutch gear 14 and the cam 17 are firmly locked across the roller 15b, and the roller 15b is rotated by a small amount Rr.
9C, the cruciform plate 22 and the clutch pinion 9a can be rotated together with the operating pin 19a to transmit left rotation power as well as right rotation of the motor. In this way, the forward and reverse rotational power from the motor for automatic focus adjustment can be transmitted and driven in the same manner as in the conventional connection state.

Next, the motor is stopped and the manual adjustment cylinder 6 is stopped.
Considering the case where a manual force is applied to the clutch pinion 9a, the manual force reversely transmits the output pinion 9e and the reduction gear trains 9d, 9c, 9b, which are transmission mechanisms, from the manual adjustment cylinder 6.
It is transmitted to. Now, when the rightward rotation of the arrow is applied as shown in FIG. 2 (IV), the operating pin 19a of the cruciform disk 22 moves rightward from the clutch pinion 9a and hits the left side surface of the roller 15a. Will push. At this time,
Since the cam 17 is braked against the movement as described above, only the roller 15a is opposed to the spring 16a and
7, the roller 15a rises by a very small amount δ1 with respect to the inclined surface 17a, and the lock between the clutch gear 14 and the cam 17 is released.

The U-shaped catcher 22a catches the cam pin 20a at the position where the cruciform disk 22 is rotated clockwise until the roller 15a forms a small clearance δ1 with respect to the inclined surface 17a and can be unlocked, and rotates the cam 17 clockwise together. Go. At this time, cam 1
7 and the inner cylindrical surface 14a of the clutch gear 14.
Is unlocked, and the cam 17 acts on the roller 15b on the other cam inclined surface in the direction away from the inclined surface 17b of the cam 17 for clockwise rotation. Does not hinder the rotation of the cam 17 merely by sliding on the surface of the inner cylindrical surface 14a of the clutch gear 14, and the cam 17 has a large resistance against the stopped clutch gear 14 according to the right rotation force of the clutch pinion 9a. The motor runs idle and does not transmit to the motor.

Next, when the distance is adjusted by applying a manual force in the opposite direction to the manual adjustment cylinder 6, the manual adjustment cylinder 6 rotates counterclockwise as indicated by an arrow shown in FIG. The operation pin 19a pushes the roller 15b on the left side, and the roller 15b moves to the left against the spring 16b, so that a minute gap δ2 is generated with respect to the inclined surface 17b of the cam 17, and the lock is released. Since the inclined surface 17a of the cam 17 moves in a direction away from the roller 15a when the cam 17 rotates left,
No. 7 slides on the inner cylindrical surface 14a of the clutch gear 14 together with the rollers 15a and 15b without a large resistance in the left rotation as well as the right rotation, and does not transmit to the motor side. Here, the lower side of both (IV) and (V) of FIG. 2 is omitted, but it goes without saying that the same operation is performed even at a symmetric position about the axis as described above when the motor is driven.

As described above, when driving the motor, the power for adjusting the focus of the lens can be faithfully transmitted to the distance adjusting cylinder irrespective of the direction of the motor, while the manual force during manual adjustment is not transmitted to the motor. So that light manual adjustment is possible. In addition, a lens is generally provided with a stopper at a movable limit position exceeding a distance adjustable range. However, when a strong force is applied from a motor which attempts to move further after reaching the limit position, or When the manual adjustment cylinder is moved by driving, when the adjustment cylinder is intentionally manually applied with a force in the opposite direction, the respective rollers are pushed back by the operating pins 19a and 19b of the cruciform plate 22 with a strong force. Therefore, the lock is forcibly released, and the clutch gear 14 and the cam 17 are disengaged from each other and slip, so that there is a feature that the motor and other mechanisms are not adversely affected.

[0022]

As described above, according to the structure of the present invention, it is possible to provide an inexpensive and high-quality AF lens barrel that can be adjusted at all times without providing any special switching means in the manual adjustment of the AF lens. .

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of an automatic clutch mechanism according to an embodiment.

FIG. 2 is an operation explanatory view of the automatic clutch mechanism of the embodiment.

FIG. 3 is a sectional view of a lens barrel of the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Holding frame 2 Holding frame 3 Fixed cylinder 4 Moving cylinder 5 Distance adjustment cylinder 6 Manual adjustment cylinder 10 Output shaft 11 Clutch mechanism 12 Motor 13 Motor pinion 14 Clutch gear 17 Cam 18 Clutch shaft 21 Friction plate 22 Cross plate 23 Braking plate

Claims (3)

[Claims] 1. A lens barrel in which a distance adjusting barrel and a manual adjusting barrel are connected to a motor through a connecting mechanism, the manual adjusting barrel being driven when a driving force from the motor acts on an intermediate portion of the connecting mechanism. The transmission member slides when a manual rotational force is applied to the motor from the distance adjusting cylinder, and has a function of not transmitting the manual force to the motor. A lens barrel clutch mechanism. 2. The coupling mechanism on the drive source side is cylindrical,
There is a cam disc having an inclined surface in the left-right direction on the inside, and a rollable roller or a ball is pressed into a wedge-shaped gap formed between the cam disc and the inner wall of the cylinder to press-contact the gap between the cylinder and the cam disc. 2. The structure according to claim 1, wherein a driven pin is provided between the left and right rollers that can be stopped in the middle of both inclinations while maintaining the locked state, and a driving force from a motor can be transmitted to the driven pin. A lens barrel clutch mechanism. 3. The cam mechanism according to claim 1, wherein the cam plate located between the driven side of the cylinder connected to the motor drive source side and the driven side of the driven pin connected to the distance adjusting cylinder side is in a left-right rotation operation. 2. A clutch mechanism for a lens barrel according to claim 1, wherein a clutch effect is exerted by applying weak braking.