JPH11326735A - Lens barrel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly reliable lens barrel which is not provided with a manual switching device and which can always perform manual adjustment other than when a lens is driven by installing a mechanism cutting off a motive power transmitting system when ordinary automatic focusing adjustment is not operated and capable of transmitting the driving of a distance adjusting barrel only when rotational motive power is obtained from a motor. SOLUTION: A driving coupling mechanism part from a motor 12 to a distance adjusting barrel 5 is parted and the connection and disconnection part of an installed clutch is always constituted of a coupling locking member energizing to a release state and a coupling ratchet. A mechanism which cuts off a motive power transmitting system when ordinary automatic focusing adjustment is not operated by performing the coupling and releasing operation of the clutch by the rotation start operation and the rotation operation just before stopping of the motor 12 and can transmit the driving of the barrel 5 only when the rotational motive power is obtained from the motor 12, is installed. Namely, this lens barrel is provided with a clutch mechanism 11 automatically operating between the motor 12 and a clutch pinion 9a, reduction gear trains 9b to 9d and an output pinion 9e.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention 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 lens barrel of an AF single-lens reflex camera provided with a clutch operating mechanism 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 troublesome switching operation and timing of photographing. Also,
If the drive motor is an ultrasonic motor, if the interlocking system is connected and the distance ring is turned by hand, the manual force will be transmitted back to the motor side, and the rotor and the stator, which maintain the pressure contact state of the ultrasonic motor, will be There was a risk of sliding and impairing 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 the above problems, the present invention relates to 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. Other than the above, a part of the drive connection mechanism from the motor to the distance adjustment cylinder is always disconnected, so that the distance adjustment cylinder can be manually adjusted without manual switching operation, and when the power of the motor during auto focus adjustment is applied, The constant rotation of the operation is used for the coupling operation of the clutch, and after the connection, the adjustment operation of the general distance adjustment cylinder is possible, and the motor stop should be operated according to the rotation program that releases the clutch by a constant reversing operation from the stop position. To solve the problem.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A drive connecting mechanism portion from a motor to a distance adjusting cylinder is cut off, and a connecting and disconnecting portion of a clutch to be installed is constituted by a connecting and locking member and a connecting ratchet constantly biased to a released state. When the normal automatic focus adjustment is not activated, the power transmission system is shut off by allowing the clutch to be engaged and disengaged by the rotation start operation and the rotation operation immediately before the stop of the motor,
A mechanism has been installed that enables the drive transmission of the distance adjusting cylinder only when the rotational power from the motor is obtained.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The best embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic perspective view of a clutch operating mechanism of the present invention, and FIG. 2 is a sectional view of a lens barrel on which the clutch mechanism of the present invention is mounted.
FIG. 3 is an operation explanatory view of the clutch mechanism of the present invention, and FIG. 4 is a circuit block diagram for operating the lens barrel of the present invention.
FIG. 5 shows a flowchart of an operation program at the time of automatic focus adjustment. In the drawings, the same members are denoted by the same reference numerals.

In the sectional view of the lens barrel shown in FIG. 2, there are a front lens unit L1 and a rear lens unit L2 around the optical axis L0. By moving the front lens unit L1 straight with respect to the lens unit L2, the focal point is adjusted. 4 shows an example of an adjustable lens barrel. The front lens unit L1 is attached to the holding frame 1 and the rear lens unit L
Reference numeral 2 denotes a helicoid part of a distance adjusting cylinder 5 which is held by a holding frame 2 and to which the holding frame 1 of the front lens unit L1 is fixed.
a and the helicoid portion 4a of the movable cylinder 4 are engaged with each other, so that the movable cylinder 4 and the distance adjusting cylinder 5 can move straight and integrally with the fixed cylinder 3. Further, since the manual adjustment cylinder 6 is located above the distance adjustment cylinder 5 and the key 5b of the distance adjustment cylinder 5 is fitted in the inner straight key groove 6a, the rotation of the manual adjustment cylinder 6 can be transmitted to the distance adjustment cylinder 5. When the relative angle between the movable barrel 4 and the distance adjusting barrel 5 changes, the straight-moving positions of the distance adjusting barrel 5 and the front lens unit L1 of the holding frame 1 with respect to the moving barrel 4 change, and the focus adjustment of the lens barrel becomes difficult. It is possible.

On the other hand, the power from the motor 12 is
2a is coupled to the clutch mechanism 11, and when the input and output are connected inside the clutch mechanism 11, the reduction gear trains 9b, 9c, 9d are passed from the clutch pinion 9a on the clutch shaft 10 of the clutch mechanism 11, and Since the manual adjustment cylinder 6 and the distance adjustment cylinder 5 are integrally rotated by the internal gear 6b of the manual adjustment cylinder 6 meshed with the output pinion 9e, the distance adjustment cylinder 5 is moved by the helicoid with the movable cylinder 4. 4, the front lens unit L1 changes the distance between the front lens unit L2 and the rear lens unit L2, thereby enabling an automatic focus adjustment operation.

In the conventional structure, the motor shaft 12a and the clutch shaft 10 are connected, and although the motor power can adjust and rotate the manual adjustment cylinder 6, it is necessary to use the motor 12 to perform manual adjustment as it is. When the motor is an ultrasonic motor, the rotor having the pressure contact structure is inadvertently rotated with respect to the stator. There was a risk of breaking the balance and impairing the characteristics.
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, this is troublesome in operation, as described above.

In the present invention, as shown in FIG. 2, a motor 12, a transmission and a clutch pinion 9a, a reduction gear train 9b, 9
c, 9d, and an output pinion 9e are provided with a clutch mechanism 11 that operates automatically, and the solution is achieved by a method that does not require a switching operation of connection disconnection at the time of manual adjustment of the distance. The structure of the clutch mechanism 11 is described below. The operation will be described in detail.

FIG. 1 is a schematic perspective view of the clutch mechanism 11. A motor pinion 13 is provided on a motor shaft 12a. The clutch pinion is fixedly mounted on a clutch shaft 10 which is a power input side of the clutch mechanism and penetrates the center. 9a is the output side. The friction gear 32 with which the motor pinion 13 is engaged is the motor transmission gear 1 around the clutch shaft 10.
4 and is strongly pressed against the surface of the motor transmission gear 14 by the friction spring 33 between the stopper rings 34 to generate a frictional holding force on the motor transmission gear. The motor transmission gear 14 unit including the integral friction gear 32 is fitted to the clutch shaft 10 in a freely rotatable state. An operating pin 15 is implanted upward in the motor transmission gear 14, and penetrates a long hole 16 a of a neutral disk 16, which is coaxially stacked.

A symmetric locking lever (left) 17 and a locking lever (right) 20 are provided on the neutral disk 16 with a locking lever shaft 23.
Ratchet 2 fixed to clutch shaft 10
5, and a spring 24 on a locking lever shaft 23 is provided with a spring hook pin (left) 18 of a locking lever (left) 17.
And (right) 21, and urged to a state where the stopper pins (left) 19 and the stopper pin (right) 22 are spread to a position where they come into contact with each other. It is kept in a non-engaged state. The tips 17b and 20b of the left and right locking levers are configured to sandwich the operating pin 15 of the motor transmission gear 14 from the left and right.

As shown in FIG. 1, the motor transmission gear 14 has a speed-increasing gear 27, a speed-increasing pinion 28 connected thereto, and a slit disk 30 fixed thereto in order to measure the movement and rotation of the operating pin 15. And an encoder constituted by a photointerrupter 31 for reading the number of passages through the slit 30a. A braking plate 26 is brought into contact with the edge of the neutral disk 16 interlocked with the rotation of the motor transmission gear 14 in order for the clutch to operate effectively with respect to the left and right rotation of the neutral disk 16, thereby giving a slight braking action.

Next, the operation of the clutch mechanism will be described in detail with reference to FIG. 3. In the case of the focus adjustment by the motor during the automatic focus operation, the rotation of the motor for the adjustment operation is either left or right. Since it is necessary to correspond, the case of right rotation and the case of left rotation will be described separately. FIG. 3 (I) is a plan view of the present clutch mechanism. Since the power transmitted from the motor pinion 13 to the friction gear 32 rotates integrally with the motor transmission gear 14, the friction gear 32 is omitted and the motor pinion 13 transmits the power to the motor transmission gear 14. It is a figure that directly meshes. Further, the output side clutch pinion 9a is omitted. FIG. 3 (II) is an operation diagram of the clutch at the time of starting the left-right rotation of the motor, and FIG.
FIG. 3 (IV) is an operation diagram for releasing the clutch by the reversing operation immediately before the motor stops.

FIG. 3 (I) when the motor is not operating
The clutch shaft 10 can freely rotate with respect to the motor transmission gear 14 as shown in FIG.
0 is loosely fitted to the ratchet 25 fixed to the clutch shaft 10 and left and right locking levers 17 and 20.
Since the claw portions 17a and 20a are spaced apart from each other by a small distance, the clutch shaft 10 can freely rotate without any restriction. For this reason, a manual force is applied to the manual adjustment cylinder 6, and the output pinion 9e, which is an interlocking gear train, the reduction gear train 9d,
c, b, even when trying to transmit to the motor side in the opposite direction via the clutch pinion 9a, the clutch pinion 9a only idles the clutch shaft 10 and does not transmit to the motor side. Becomes possible.

Next, consider the case where the motor rotates as in the automatic focusing operation. The rotation angle α shown in FIG. 3 is the rotation angle of the motor required for clutch operation, and β is the rotation angle of the motor. Is the actual operating angle of the clutch on the neutral disk 16 determined by the connecting gear ratio of the above, + symbol indicates the right rotation angle, and-symbol indicates the left rotation angle. When the motor pinion 13 starts rotating clockwise from the start position as shown in A of FIG. 3 (II), the meshed motor transmission gear 14 starts rotating counterclockwise. According to this, the operating pin 1 implanted in the motor transmission gear 14
5 also rotates together and pushes the tip 20b of the locking lever (right) 20 located on the left side of this pin to try to rotate the neutral disk 16, but the braking disk 26 is in contact with the neutral disk 16. Therefore, the neutral disk 16 does not start moving because the braking works. For this reason, the locking lever (right) 20 is depressed against the urging force of the spring 24 according to the left movement of the operating pin 15 about the locking lever shaft 23, and the ratchet 25 at the center is moved.
The claw 20a of the locking lever (right) 20 meshes with the teeth of
The locking lever (right) 20 is connected to the ratchet 25. This is because the motor pinion 13 is α
The connection is made at a position where the angle has been turned to the right, that is, at a position where the operating pin 15 has been turned to the left by the β angle.

When the rotation is further continued, the operation pin 15 is rotated by the left rotation of the motor transmission gear 14 as shown in FIG.
Holds the locking lever (right) 20 and rotates while overcoming the braking of the brake plate 26 of the neutral disk 16 while being connected to the ratchet 25. 9b,
The manual adjustment barrel 6 can be driven to rotate through c, d, and the output pinion 9e, and the focus adjustment can be performed by moving the distance adjustment barrel 5.

Next, the motor stop mode, which is a feature of the present invention, will be described. If it is desired to reach the in-focus position and stop moving during focus adjustment by driving the motor, the motor should be stopped in the conventional drive mode. In the mechanism of the present invention, the clutch must be in the disconnected state when the motor is not operated, so the α-angle inversion operation of the clutch release operation from the stop position is obligatory. FIG. 3 (IV) shows this stop operation mode. Now, the motor is driving right rotation,
When a stop command is issued due to reaching the in-focus position, the motor reverses the left angle (left rotation). As a result, the operating pin 15 of the motor transmission gear 14 rotates to the right by β angle while the neutral disk 16 and the ratchet 25 are left at the positions, so that the locking lever (right) 20 moves away from the center by the restoring force of the spring 24. Then, the pawl 20a releases the bite of the ratchet, returns to the clutch release fixed position, and stops the motor rotation. As a result, the clutch returns to the free state in which the clutch is disconnected as shown in FIG.

Similarly, in the case of the left rotation of the motor, FIG.
As shown in FIG. 3B, the claw portion 17a of the locking lever (left) 17 engages with the ratchet 25 in the process of the right rotation start of the motor transmission gear 14 and the actuating pin 15 moves rightward by β angle to engage the clutch. If the left rotation of the motor is continued as it is, it rotates while overcoming the braking of the brake plate 26 of the neutral disk 16 in the coupled state as shown in B of FIG. 3 (II), as in the case of the right rotation of the motor. The left rotation power of the motor 12 can be transmitted to the manual adjustment cylinder 6.

When the stop position is to be obtained from the left rotation driving state of the motor, similarly to the case of the stop from the right rotation of the motor described above, the motor is inverted by an α angle (right rotation) and the operating pin is rotated. By rotating the lever 15 counterclockwise by the angle β, the locking lever (left) 17 releases the connection with the ratchet 25 and returns to the state shown in FIG. As described above, for the control operation by the normal motor of the normal rotation and the reverse rotation of the motor, the clutch is engaged each time, the focus adjustment can be performed, and when the motor is stopped, the clutch is released and then the motor is stopped. Since the stop mode of the program is required, it can be understood that manual adjustment of the manual adjustment cylinder 6 can be easily performed.

In order to control the drive of the clutch and the focus by the rotation program in the start and stop operations of the motor as described above, an encoder and a control circuit for detecting the rotation of the motor are required. From the speed-increasing gear 27 to the speed-increasing pinion 28
The slit 30a is detected by the photointerrupter 31 by the rotation of the slit disk 30, and converted into a pulse number to be used as a control signal. The main part of the AF control system including the actual AF single-lens reflex camera and the interchangeable lens has the configuration shown in FIG.

In the distance measuring system of the AF single-lens reflex camera, the subject light L0 transmitted through the interchangeable lens is guided to a main mirror 40 installed at 45 ° in a mirror box of the camera body, and the finder light and the distance measuring light of the subject are obtained. Divided into In general, the distance measuring light passes through the substantially central transmitting portion of the main mirror 40, is guided downward by the rear sub mirror 41, is received by the AF sensor 43 through the separate lens 42, and is processed as distance measuring information. . The distance measurement information obtained by the AF sensor 43 is used as a distance measurement signal p for AF C
The signal is sent to the PU 44 and subjected to arithmetic processing. After communication of the signals r and q with the main CPU 45, a defocus (focus error) signal
Alternatively, the focus determination signal s of the focusing signal is sent to the lens CPU 46 on the lens side through the camera-side signal terminal 49b and the lens-side signal terminal 48b. On the basis of the signal s, the lens CPU converts the correction amount of the focus error into the movement amount of the lens, sends it to the driver 47 as a motor rotation command signal v, and rotates the motor 12 by the driving signal w generated from the driver 47, Drive the distance adjustment barrel. As described above, the slit disk 30 is rotated in accordance with the rotation of the motor, and the slit is read by the photo interrupter 31 as an encoder signal y.
And drives the lens to the in-focus position while measuring the amount of movement of the lens. The lens side moves, or the result of the movement is sent as a signal u to the camera body through the lens signal terminal 48a and the camera side signal terminal 49a, and the distance is repeated to approach the best focus position. The focus determination is transmitted from the camera body to the lens side as an f signal, and the lens drive is stopped, and the focus adjustment is completed only after that. In the present invention, an operation program that takes into account the clutch operation is also required in general automatic focus control, and a flowchart for explaining this is shown in FIG.

Here, the motor rotation angle α required for the clutch operation is equivalent to m pulses in the signal y of the encoder (61), and the movement correction amount due to the focus error is described as n pulses. The lens side starts from the activated state (50),
First, the description will be made on the assumption that the lens is aimed at the subject for the first time. The subject error light is received by the AF sensor on the camera side, and the focus error amount resulting from the distance measurement calculation is sent to the lens side CPU 46 as a defocus signal s. Lens CPU
In step 46, the movement amount based on the error amount corresponding to the extension amount of the lens barrel of the present lens is calculated, and the pulse signal n of the encoder is obtained (51). Next, in (52), it is determined whether the rotation direction is right or left. If it is determined to be rightward, it is determined in the next (55) whether rightward rotation is the first operation. This is to determine whether the clutch described later is in the engaged state or the released state. Since this is the first AF operation, the flow proceeds to (56) with Yes. (56) is for determining whether or not clockwise rotation is necessary because it has to return after passing through the in-focus position which will be described later. In this case, it is determined as No, and in (57), the motor is rotated to the right. Begin to. This corresponds to FIG. 3 (A) A for explaining the operation, in which the number of pulses is measured while receiving the signal y from the encoder (61), and the rotation is continued until m pulses of the clutch operation are completed in (58). When the counting of the m pulses is completed, it is considered that the clutch engagement is completed in (59), and it is assumed that the lens movement by the right rotation drive starts from that point, and the encoder signal y is measured again to control the movement amount of the lens. become.

If the clockwise rotation continues, this corresponds to FIG. 3 (III) A, and the first general AF after shifting to (64) in FIG.
Operation. (65) is for determining whether the focus adjustment operation is being performed in the lens distance adjustment movable range or whether the photographer is not obstructing the movement of the lens.
If the encoder signal can be detected within t, it means that the distance adjusting cylinder 5 can be moved. If there is no encoder signal, the friction gear 32 slips and rotates with respect to the motor transmission gear 14 even if the motor rotates, and the distance adjustment cylinder 5 is adjusted. This means that the cylinder 5 cannot be moved. It can be determined that the movement is prevented by the stopper because the movement range of the lens is exceeded, or the movement of the lens is hindered in some way. If the encoder signal y is obtained within the time Δt, the number of pulses is measured in (66), and it is determined whether or not the movement has been performed by the number n of pulses of the defocus amount. If No, the process returns to (64) and the clockwise rotation is continued until the counting of n pulses is completed. While the lens barrel 5 is being moved by the rotation of the motor, a movement signal u is sent from the lens side CPU to the camera side as described with reference to the circuit block diagram of FIG. It is configured so that you can check it.

When the n-pulse counting is completed in (66), a u signal is sent to the camera side to determine whether or not focusing has been obtained, and the lens side determines in-focus by the focusing signal f in (67). Is determined. In the case of Yes, the motor is not stopped at this point, and the motor is inverted by m pulses (left rotation) in (68) and (69). This is Figure 3 (IV)
As described in the description of the stop mode, the locking lever (right) 20 of the clutch mechanism 11 performs the m-pulse left rotation operation to obtain the operating angle α required to release the locked state from the ratchet 25, and (70) ) To complete the clutch release (7
The motor is stopped in 1), and this series of operations is completed in (76).

If the encoder signal y cannot be obtained within the time .DELTA.t at the judgment position (64), which is slightly returned, the distance adjustment cylinder 5 cannot be moved for some reason. Jumps to (68),
In (68) and (69), the motor is operated by inverting m pulses,
After releasing the clutch at (70), the motor is stopped at (71). In any case, when it is necessary to stop the motor, the operation program is required to reverse the motor, disengage the clutch, and then stop.

The clockwise rotation operation of the motor has been described above, but the distance measurement information (73) obtained by the distance measurement unit (72) for camera measurement uses the distance adjustment cylinder 5 because the defocus signal s is in focus. In the opposite direction, i.e., left rotation,
Since it is No in (52), the flow moves to the left rotation operation. The following logical flow is a symmetrical shape in which the rotation direction in the right rotation is only reversed, and (53) is the right rotation (55).
(54) corresponds to (56) of clockwise rotation, and
5) is also the same and will not be described.

Next, considering the case where the focus determination (67) is No, if the focus signal f is not obtained, u
The signal returns to the distance measurement operation (72) on the camera side, and a request for re-ranging is sent. The resulting defocus signal s is sent to the lens side, and the logical operation of determination and operation is repeated from the beginning of the flow. . In this case, a different clutch operation is performed depending on whether the position at which the distance adjusting cylinder 5 is moved by n pulses is insufficient or excessive with respect to the best focus position. Therefore, the description will be made in two ways.

One is that if the best focus position has not yet been reached even after the motor has been rotated clockwise and the distance adjusting cylinder 5 has been moved n pulses, the motor rotation direction (52) can be clockwise rotation in the same direction. In the following (55), since the clockwise rotation is continued in the next (55), the clutch can be kept connected by the judgment of No, so that the clutch does not operate and the distance adjusting cylinder 5 in (64)
By repeating the operation as described in the above operation while continuing the movement, the movement correction for the shortage to the best focus position is performed.

The next one is the first AF operation (53),
(54) When the motor is rotated leftward according to the following flow, n
After moving the distance adjustment 5 by a pulse, if the result of the re-ranging is too far from the best focus position and needs to be returned, it is necessary to convert from left rotation to right rotation. This is a result of Yes in (52), and in the next (55), the clockwise rotation is the first time, and in (56), the clockwise rotation for the return operation is Yes. . Up to now, the clutch has been engaged by left rotation, so the clutch is once disengaged by m-pulse right rotation while counting the encoder signal y in (60) and (62), and further right-rotation movement is performed by further m-pulse right rotation. Is completed in (63). In this manner, the clutch operation for the return operation switches the clutch connection by rotating 2 m pulses, that is, rotating the motor by 2α angle as shown in (62). Similarly, when the distance adjustment cylinder 5 is moved by the first right rotation drive and the return correction drive must be performed by the next operation, the flow proceeds to the operation program of the flow (53) and (54) from the determination of the rotation direction of (52). , Which is omitted in (75) below,
In order to enable the left rotation drive at the symmetrical position corresponding to (0) and (62), the same applies to the case where the clutch is switched to the left by a 2 m pulse to rotate leftward. As described above, the program operation by the rotation of the motor of the clutch mechanism having the simple structure does not require the provision of the clutch mechanism having the individual structure.
It is possible to provide a lens barrel that can be manually adjusted at all times other than at the time of desired driving.

[0032]

As described above, according to the structure of the present invention, there is provided an inexpensive and high-quality AF lens barrel which can always be manually adjusted without any special switching means in the manual adjustment of the AF lens. it can.

[Brief description of the drawings]

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

FIG. 2 is a sectional view of a lens barrel of the embodiment.

FIG. 3 is an operation explanatory view of the clutch mechanism of the embodiment.

FIG. 4 is a circuit block diagram.

FIG. 5 is a flowchart of an operation program in the embodiment.

[Description of Signs] 1 Front lens unit L1 holding frame 2 Rear lens unit L2 holding frame 3 Fixed tube 4 Moving tube 5 Distance adjusting tube 6 Manual adjusting tube 10 Clutch shaft 11 Clutch mechanism 12 Motor 13 Motor pinion 14 Motor transmission gear 15 Operating pin 16 Neutral disk 17 Lock lever (left) 18 Spring pin (left) 19 Stopper pin (left) 20 Lock lever (right) 21 Spring pin (right) 22 Stopper pin (right) 23 Lock lever shaft Reference Signs List 24 spring 25 ratchet 26 brake plate 27 speed-up gear 28 speed-up pinion 30 slit disk 31 photo interrupter 32 friction gear 33 friction spring 34 stopper ring 40 main mirror 41 sub-mirror 42 separator lens 43 AF sensor 44 AF CPU 45 main CPU 46 lens PU 47 drivers 48a, b signal terminals 49a, b signal terminal

Claims (3)

[Claims] An encoder is installed at a position where the rotation of a motor transmission gear can be measured, and the number of pulses of the encoder is measured when the motor is driven to adjust the focus. In the middle of the transmission mechanism, the connection operation is performed by m pulses of the encoder due to the initial rotation of the motor, and the distance adjustment cylinder can be driven by the motor,
When the motor is stopped, a clutch mechanism is provided to release the connection by a motor reversing operation of the encoder m pulse from the stop position, and the distance adjusting cylinder can be manually adjusted at any time except when the motor is operated. Lens barrel. 2. A motor drive gear coupled to the motor side and a neutral disk having a pair of symmetric locking levers which provide weak braking and are normally urged toward the outside of the center, are coaxially stacked, By means of a device in which the shaft fixing the pinion and ratchet connected to the distance adjusting cylinder side in their central holes is loosely fitted and installed, the power transmission system is normally in a cut-off state, and either the forward or reverse rotation from the motor is performed. When the power is transmitted, one of the locking levers is brought to the center by the action pin of the motor transmission gear, and the power transmission system is coupled by engaging with the ratchet, and the distance adjusting cylinder is driven by the motor. 2. The lens barrel according to claim 1, further comprising a clutch mechanism having a function of enabling the lens barrel. In the automatic focus adjustment, a motor rotation control method in which a clutch operation is added according to various situations is determined, and an appropriate automatic focus adjustment is made possible by selectively operating an adjustment operation program according to the method. The lens barrel according to claim 1, wherein: