JPH0365909A - lens barrel - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a zoom lens barrel, and in particular, to a zoom lens barrel that can be manufactured at a lower cost than conventional products, is easier to operate, and has better quick-shooting properties than conventional products. It is related to the cylinder.

[Prior Art] Conventionally, so-called electric zoom lens barrels and electric zoom cameras have been constructed so that a focusing lens is moved by motor power, and a zoom lens is also moved by motor power. has been commercialized, but since this known electric zoom lens barrel and electric zoom camera are equipped with a motor for driving a focusing lens and a motor for driving a variable magnification lens, the lens barrel and the camera are large. It has the drawbacks of being bulky, heavy, and expensive.

On the other hand, there have also been proposals for electric zoom lens barrels and electric zoom cameras that are configured so that a common motor drives the focusing lens and the variable magnification lens, and examples of such proposals include: As, for example, U.S. Pat. No. 337
The invention disclosed in the specification of No. 0907 and JP-A-60-26
There is an invention disclosed in Publication No. 3911.

The invention described in U.S. Pat. When the motor rotates in reverse, the focusing lens is driven toward the infinity position, while in the case of zooming, when the motor rotates forward, the variable power lens is driven in the telephoto direction, and when the motor is reversed, the variable power lens is driven toward the telephoto direction. Since the switch for instructing the driver to drive the camera in the wide direction) is provided separately, there is a drawback that the operation is complicated. Further, although this invention does not describe that focusing is performed by autofocus, even if the focusing mechanism in this invention were configured with an autofocus mechanism, there would be a switch for selecting the telephoto direction and the wide direction during zooming. must be provided separately from the focus and zoom switching operation section, so the troublesome operation when performing the zoom operation cannot be improved.

On the other hand, Japanese Patent Application Laid-Open No. 60-263911 discloses that a solenoid is controlled via a control circuit to switch between focus and zoom according to instructions from a zoom tele (T) and wide (W) changeover switch (zoom switch). However, in this invention, in addition to a switch for selecting either telephoto or wide, a solenoid and a clutch mechanism interlocked with the solenoid,
Since a control circuit for the solenoid must be provided, the cost is high. Furthermore, since the solenoid is energized each time the zoom switch is operated to the telephoto or wide-angle side, power consumption is large, and there is another drawback in that it is necessary to frequently replace the battery.

Therefore, the applicant has developed a new lens barrel that eliminates the drawbacks inherent in the prior art, and has filed a patent application for the lens barrel.

The novel lens barrel proposed by the applicant has a switching gear that is positioned by the force of a biasing means such as a spring at a position where it always meshes with the focus drive system gear when no zoom operation is performed. The lens barrel is moved to a position where the switching gear overcomes the force of the biasing means and meshes with the zoom drive system gear only when a force is applied by a human finger to a variable magnification operating member such as a zoom button. It is configured so that

The lens barrel proposed by the applicant does not require any switching operation to switch between zooming and focusing, and does not require an electrical actuator or the like to switch between zooming and focusing. Therefore, the problems inherent in the aforementioned inventions (US Pat. No. 3,370,907 and Japanese Patent Application Laid-Open No. 60-283911) were completely solved.

[Problems to be Solved by the Invention] However, the prior art (unpublished) lens barrel proposed by the present applicant also had the following problems that should be further improved.

In the lens barrel, as soon as the user stops pressing the zoom button, the switching gear is returned from the zoom drive position to the focus drive position by the biasing means, so that the switching gear is in mesh with the zoom drive system gear. It is desirable that the motor also stop at the same time when the motor is released. However, even if an electrical control operation is performed to stop the motor at the time when the switching gear and the zoom drive system gear disengage, there is a time lag until the motor actually stops. The motor has not yet come to a complete stop even when the switching gear starts to mesh with the focus drive system gear, and as a result, there is a risk that the focus drive system gear will be rotated by the motor.

It is therefore an object of the present invention to provide an improved lens barrel, which makes it possible to completely eliminate the above-mentioned risks.

[Means for Solving the Problems] The present invention appropriately lengthens the time it takes for the switching gear to move from the meshing position with the zoom drive system gear to the meshing position with the focus drive system gear, and after the motor has stopped. The present invention is characterized in that the switching gear and the focus drive system gear are meshed with each other. In the embodiment of the present invention described below, movement of the switching gear is prevented when the switching gear moves from a position of engagement with the zoom drive system gear to a position of engagement with the focus drive system gear. A viscous resistance generating means for generating a viscous resistance force in the direction is provided in association with the switching gear.

[Function] When either the push button 123 or the wide button 124 is not pressed, the switching gear 118 is always engaged with the gears 109 and 128, and the motor 104
The rotation is transmitted to the gear 12 via the gear 128 and shafts 10 and 11, and the 1811J lens barrel 5 is rotated by the first movable lens barrel gear portion 5b that is engaged with the gear 12 and is directed in the optical axis direction. It is becoming more and more beautiful. Therefore, when a magnification change operation is not performed, focusing is always possible.

When either the tele button 123 or the wide button 124 is pressed, the switching gear supporting shaft 117 supported on the movable plate 119 and the switching gear 118 supported on the shaft 117 are moved by the force of the spring 127. against gear 115
Since the switching gear 118 is engaged with the gear 115, power zooming by the motor 104 becomes possible.

When the tele button 123 and the wide button 124 are no longer pressed, the movable plate 119 starts to move from the position where it is engaged with the gear 115 toward the front side of the lens barrel by the force of the spring 127. When the plate 119 moves forward, the piston 133 is pushed inside the cylinder 132 toward its head side via the piston rod 131 fixed to the bent portion 119C of the movable plate 119, so that the piston head and cylinder head (the left end in FIG. 2) is compressed, and the resistance force of the fluid reduces the moving speed of the movable plate 119 to the left (towards the tip of the lens barrel). Ru. and,
The fluid flows through a narrow relief hole 1 provided through the bis-ton 133.
Chamber 1 on the right side of cylinder 132 through 33a
32b, the piston 133 and the movable plate 119 move toward the tip of the lens barrel at a speed proportional to the rate of decrease in the axial length of the chamber 132a between the piston head and the cylinder head. . Therefore, the movable plate 11
Since the leftward movement speed of lens 9 is slower than when the cylinder 132 and piston 133, which are viscous resistance force generating means, are not provided, the switching gear 118 is moved to the position where it starts to mesh with the focus drive system gear 128. At this point, the motor 104 has completely stopped, and therefore, in the lens barrel of the present invention, there is no risk that the focus drive system gear 128 will be rotated by the voluntary rotation of the motor 104.

[Embodiment 1] An embodiment of the zoom lens barrel of the present invention will be described below with reference to FIGS. 1 to 1z.

FIG. 1 is a vertical cross-sectional view of a main part of a zoom lens barrel according to an embodiment of the present invention, FIG. 2 is a developed plan view of a structural part related to the present invention, and FIG. 3 is a view from the top of FIG. 2. Cross-sectional view, Figures 4 and 5
The figure is a developed plan view of the zoom mechanism, FIG. 6 is a schematic front view of a part of the structure shown in FIG. 1, FIG. 7 is a sectional view of the drive shaft system included in the structure shown in FIG. FIG. 8 is a detailed view of a part of the structure shown in FIG.

In FIG. 1, 1 is a known mount that is attached to a camera body (not shown) so that it can be worn under the skin, 2 is a fixed tube fixed to the mount 1 with screws 22, and 21 is fixed to the outer periphery of the fixed tube 2 with screws 23. 3 is a linear cylinder that is fitted on the outer periphery of the fixed cylinder 2 and is supported so as to be movable only in the axial direction; 4 is arranged outside the linear cylinder 3 and is rotatable with respect to the fixed cylinder 2; a zoom drive ring supported by 5
is arranged outside the linear cylinder 3 and the zoom drive ring 4, and is threadedly engaged with the linear cylinder 3.
A movable lens barrel 6 is disposed inside the fixed barrel 2, and a second movable barrel 17 is movable in the axial direction by engaging with the fixed barrel 2 and the linear barrel 3 in a cam engagement relationship described later. is a known aperture mechanism fixed to the fixed cylinder 2 with screws 19,
Reference numeral 18 denotes an aperture drive motor integrated with the aperture mechanism 17, Ll denotes a first group lens fixed to the movable lens barrel 5, and L2 denotes a second group lens fixed to the tip of the fixed barrel 2. , L3 is a third lens group fixed to the tip of the second movable lens barrel 6, L4 is a fourth lens group fixed to the middle part of the fixed barrel 2, and Ls is the rear end of the second movable lens barrel 6. The fifth fixed at
A group lens; 9 is a drive unit disposed in an annular space formed outside the rear end of the fixed barrel 2; 20 is for information communication and power exchange between this zoom lens barrel and a camera body (not shown); This is a group of connection terminals for performing.

The coupling relationship between the constituent members will be further explained below. A telephoto button 123 and a wide button 124 for zooming operation are arranged on the top surface of the exterior barrel 21, and these two buttons are located in the space between the exterior barrel 21 and the upper outer peripheral surface of the first movable lens barrel 5. Related mechanisms are arranged, and these structures will be explained in detail later.

As shown in FIG. 4, a curved cam groove 28 and an axial groove 2b are formed through the peripheral wall surface of the fixed cylinder 2. As shown in FIG.

On the other hand, on the inner circumferential surface of the linear cylinder 3 outside the fixed cylinder 2, there are diagonal grooves 3 with a lead angle as shown in Figures 1 and 4.
d is engraved, and a driven roller 7 protruding perpendicularly from the outer peripheral surface of the second movable barrel 6 is inserted into the cam groove 2a of the fixed barrel 2 and the diagonal groove 3d of the linear barrel 3 so as to be relatively movable. has been done. The driven roller 7 is a cylindrical body, and a protrusion is provided on the outer circumferential surface of the rear end of the linear cylinder 3, which is rotatably fitted to a shaft screw 8 fixed to the outer circumferential surface of the second movable lens barrel 6. 3a is formed, and the protrusion 3a is '! As shown in FIG. J4, it is inserted into a diagonal groove 4a carved in the inner peripheral surface of the zoom drive ring 4 so as to be relatively slidable therein. Further, the K-threaded portion 3b formed on the outer circumferential surface of the distal end of the linear barrel 3 is threadedly engaged with the threaded portion 5a formed on the inner circumferential surface of the distal end of the first movable lens barrel 5.

Further, a protrusion 3c is provided on the inner circumferential surface of the rear end of the straight cylinder 3, and the protrusion 3c is located opposite to the axial groove 2b on the outer circumferential surface of the fixed cylinder 2, as shown in FIG. Slidably fitted.

A gear portion 4b is formed on the inner peripheral surface of the rear end portion of the zoom drive ring 4, and a gear 16 meshes with the gear portion 4b. The gear 16 is fixed to the tip of the shaft 15, and
5 is adapted to be rotationally driven by a drive unit 9, which will be described later.

A bayonet engagement groove 4c (i.e., circumferential groove) is provided at the rear end of the zoom drive ring 4 for bayonet coupling (i.e., detachable coupling) of the ring 4 to the fixed cylinder 2.
is formed and the bayonet engagement groove 2 of the fixed cylinder 2 is formed.
A bayonet engaging protrusion 4d that fits into C is formed. That is, the zoom drive ring 4 is rotatably supported by the fixed cylinder 2 by bayonet engagement.

As shown in FIG. 6, a circular arc groove 5c extending in the circumferential direction is formed on the outside of the lens support portion of the first movable lens barrel 5, and a shaft supporting the gear 12 is formed in the groove 5c. 11 is slidably inserted along the longitudinal direction of the groove 5C. The gear 12 meshes with a gear portion 5b formed on the first moving mirror wJ5 parallel to the groove 5C, and as will be explained later, when the shaft 11 is rotated, the first moving lens barrel 5 moves along the optical axis. The shaft 11 is rotated about the optical axis, and the shaft 11 slides relative to the optical axis in the circumferential direction within the groove 5C.

A shaft 11 fixed to the gear 12 is a shaft for transmitting the driving force for focusing, and the shaft 11 extends parallel to the optical axis in the space inside the fixed barrel 2, excluding its tip. Most of it is inserted into a cylindrical shaft 10, which will be described later. The cross-sectional shape of the fitting portion between the shaft 11 and the cylindrical shaft 10 is the seventh shape.
The shape shown in the figure is such that a flat surface 10a formed on the inner peripheral surface of the shaft 10 and a flat surface 11a formed on the outer peripheral surface of the shaft 11 are in surface contact, and both shafts 10 and 11 rotate. When a force is applied, they rotate together, but they are fitted in such a way that they move relative to each other in the axial direction.

The tip of the shaft 11 is rotatably supported by a bearing member 13 shown in FIGS. 1 and 8.

As shown in FIG. 8, the bearing member 13 has a forked portion 13a that engages with the outer peripheral surface of the shaft 11 in a relatively slidable manner, and is fixed to the linear cylinder 3 with screws 14.

The rear end of the cylindrical shaft 10 is rotatably supported in a bearing hole 101h of a drive unit support frame, which will be described later, and a gear 128, which will be described later, is fixed to the rear end of the shaft 10.

Next, the configuration related to the present invention will be explained with reference to FIGS. 1 to 3.

In FIGS. 1 to 3, 123 is a tele button that is pressed down by the camera user (therefore, when moving the photographing optical system toward a long focus direction, and 124 is a tele button that is pressed when moving the photographic optical system toward a short focus direction. Wide button operated, 12
5 is a variable power button support member made of an elastic material that bends only when both buttons are pressed down to allow the button to move downward;
119 is the inclined surface 12 of the leg portion 123a of the tele button 123
Slope 119a and wide button 124 slidingly contacting 3b
The inclined surface 11 slidingly contacts the inclined surface 124b of the leg portion 124a of
A movable plate 117 has a bent portion L19c at the rear end and a flange 117a formed in the intermediate portion, and is supported by the bent portion 119c of the movable plate 119. 101 is a drive unit support frame that supports the gear group and motor of the drive unit 9, and 118 is attached to the rear end of the switching gear support shaft 117 so that it can only rotate. The switching gear 120 shown in FIG.
This is a spring that is loosely fitted onto the shaft 117 between the bent portion 119c of the shaft 117 and always urges the shaft 117 backward (towards the right in FIGS. 1 to S3).

The drive unit supporting frame 101 has a circumferentially extending portion that extends in the circumferential direction of the zoom lens barrel within the space between the exterior barrel 21 and the upper outer circumferential surface of the first movable barrel 5, and an axis of the lens barrel. The frame 101 has an axially extending portion extending forward in parallel with the circumferentially extending portion, and the frame 101 is secured to a fixed cylinder by screws 102 and 103 at both ends of the circumferentially extending portion, as shown in FIG. It is connected to 2.

As shown in FIG. 2, the circumferentially extending portion has a hole 101g for supporting the switching gear supporting shaft 117, a hole 101h for supporting the shaft 10, and a hole IQI i for supporting the shaft 15.
In addition, a mounting hole 101f for the motor 104 and the like are provided through the shaft, and five gear mounting shafts 101a to 101e are provided protrudingly. The other end of each of the gear attachment shafts 101a to 101e is fixed to a cover/bearing plate 113 disposed directly opposite the frame 101.
01 and the cover/bearing plate 113, a group of gears forming the drive unit are disposed, which are loosely fitted to the gear attachment shafts 10ia to 101e.

In FIG. 2, 105 is a pinion fixed to the shaft of the pinion 104, 10B is a known pulse plate having teeth 106a on the outer peripheral edge and fixed to the pinion 105, and 10B is a known pulse plate fixed to the pinion 105.
7 is fixed to the frame 101 and a light projector IQ.
7a and a light receiving part 107b, a rotation amount detection means such as a known photointerrupter, and 108 has a large gear part that meshes with the binion 105 and a small gear part that meshes with the gear 109, and is loosely fitted to the gear mounting shaft Iota. The stepped wheel-shaped gear 109 has a small gear part that constantly meshes with the switching gear 118 and a large gear part that meshes with the small gear part of the gear 108, and is supported by a loose fit on the gear mounting shaft 101b. A gear 115 is rotatably fitted to a shaft 114 fixed to the cover 113 and arranged in alignment with the gear 128. A gear 110 is rotatably fitted to a gear attachment shaft 101c and is connected to the gear 115 and the gear described below. Gear meshing with gear 111, 111 is gear mounting shaft 1
A gear 112 is rotatably fitted to the gear mounting shaft 101e and meshes with a gear 110 and a gear 112, which will be described later.
1 and gear 116, and 11B is a gear fixed to shaft 15 for transmitting zooming driving force.

The switching gear 118 is selectively engaged with either the gear 128 or the gear 115 when the movable plate 119 is moved parallel to the optical axis.

The axially extending portion of the drive unit supporting frame 101 that extends forward parallel to the shaft 11 is shown in FIGS. 1 and 3.
As shown in the figure, it has a flat box shape with side walls and a front wall, and a movable plate 119 is attached to the upper edge of the side wall.
A guide rail portion 101 for guiding parallel to the shaft 11
j'Et and 101k are formed. Further, the spring hooks formed on the front wall of the frame 101 are engaged with the holes 1011, and the spring hooks provided on the bent portion 119C at the rear end of the movable plate 119 are engaged with the holes 119d in which the locking portions at both ends of the springs 127 are engaged. The movable plate 119 is urged forward by the spring 127.

As shown in FIG. 2, between the front wall of the flat box-shaped portion of the frame 101 and the bent portion 119C at the rear end of the movable plate 119, a viscous resistance consisting of a cylinder and a piston is installed parallel to the spring 127. Force generating means are installed.

The viscous resistance force generating means includes a cylinder 13 fixed to the front wall of the frame 101 and extending parallel to the shaft 11.
2. A fixed piston rod 131 fixed to the bent portion 119C at the rear end of the movable plate 119 and inserted into the cylinder 132; fixed to the fixed piston rod 131 and movable in the cylinder 132 in the relative axial direction; It is composed of an inserted piston 133. The piston 133 is provided with a fluid escape hole 133a for connecting the head side chamber 132a and the lower side chamber 132b of the cylinder 132.
Both chambers 132b and 132b are sealed except for communicating with the fluid escape hole 133a of the piston, and are closed to contain viscous fluid (air).

oil, grease, etc.).

Also shown in FIGS. 1 and 3 is a flat box-shaped portion of the frame 101 extending parallel to the axis 11. As shown in FIGS. 2, the square hole 121a for inserting the leg 123a of the tele button 123 and the leg 124 of the wide button 124.
A guide plate 121 having a square hole 121b for inserting the button A is fixed thereto, and a variable-power button support member 125 for supporting both buttons is fixed on the guide plate 121.

A flexible printed board 125 is placed on the guide plate 121.
is mounted on the printed board 126, and conductive patterns 126a and 126b constituting a switch for detecting a variable magnification operation are formed directly below the tele button 123 and the wide button 124, respectively. On the other hand, on the zoom button support member 125, a conductive protrusion 125a that can contact the conductive pattern 126a is formed at the lower surface of the tele button 123, and a conductive protrusion 125b that can contact the conductive pattern 126b is formed on the wide button. The conductive pattern 126a and the conductive protrusion 125a constitute a wide direction magnification change operation detection switch. In addition, the flexible printed board 126
is electrically connected to the lens barrel control circuit in the zoom lens barrel of the present invention, and the motor 104 and the aperture drive motor 18 (FIG. 1) are also connected to the control circuit.

As shown in FIG. 2, the circumferentially extending portion of the drive unit carrying frame 101 extends forward (to the left in FIG. 2).
A switch mounting portion 101m is formed projecting toward the switch mounting portion 101m, and switch pieces 129 and 130 are mounted to the switch mounting portion 101m with screws 132 via an insulating plate 131.

The tip 129a of the switch piece 129 is always in contact with the rear surface of the bent portion 119c of the movable plate 119. The tip 130a of the switch piece 130 is the tip 129 of the switch piece 129.
In the state shown in FIG. 2 where the switching gear 118 is in mesh with the gear 128, the switch piece 1
The tip of the switch piece 130 is spaced a predetermined distance behind the switch piece 29.

Switch piece 129 and switch piece! 30 constitutes a switching gear movement status detection switch for detecting the movement status of the switching gear 118,
The switch is also electrically connected to the control circuit.

The lens barrel control circuit mounted in the zoom lens barrel of the present invention is connected to the main body in the camera body (not shown) via a connection terminal group 20 (FIG. 1) provided on the rear end surface of the mount 1. The lens barrel control circuit and main control circuit are electrically connected to the control circuit, and the lens barrel control circuit and main control circuit include a changeover gear movement status detection switch (switch consisting of switch pieces 129 and 130) and a variable magnification operation detection switch (see Figure 3). ) The motor 104 and the diaphragm drive motor 18 are controlled in accordance with the detection signal.

FIG. 9 is a schematic diagram illustrating the control system of the zooming and focusing drive systems in the zoom lens barrel of this embodiment.

In FIG. 9, 141 is a switch that is closed when the wide button 124 (FIG. 2) is pressed and is composed of a conductive protrusion 125b and a conductive pattern 126b, and 142 is a switch that is closed when the wide button 124 (FIG. 2) is pressed. The switch 143 is a switch that is closed when pressed and is composed of a conductive protrusion 125a and a conductive pattern 126a, and the switch 143 is a switch composed of switch pieces 129 and 130 (FIG. 1). 129 tip L29a and the tip 130 of the switch piece 130
a switch that is closed upon contact with a, 140
106 is the pulse plate, 107a is a light emitting portion of the rotation amount detecting means consisting of a light emitting diode, etc., and 107b is a phototransistor. 118 is the switching gear that is movable in the axial direction; 109 is the final stage gear on the drive side that is always in mesh with the switching gear 118; and 115 is the switching gear that is only used when a magnification change operation is performed. Gear meshing with 118, 12
Reference numeral 8 denotes a gear that transmits the driving force of the motor 104 to the focusing drive shaft (shaft 10 in FIG. 1) when no zooming operation is performed.

Next, the operation of each part of the zoom lens barrel of the present invention will be explained with reference to FIGS. 1 to 12.

(1) When the scaling operation is not performed.

The zoom lens barrel is in the second position when no zooming operation is performed.
The state shown in FIGS. 3 and 3 is maintained, and autofocusing is possible.

As shown in FIGS. 2 and 3, press the tele button 123'E.
When neither the L nor the wide button 124 is pressed, the movable plate 119 is biased toward the left in FIG. There is. The switching gear supporting shaft 117 supported by the movable plate 119 and the switching gear 118 rotatably supported by the shaft 117 are also biased to the position shown in FIG.
They are interlocked.

During focusing, the driving force of the motor 104 is transmitted to the gear 105, gear 108, gear 109, switching gear 118, and gear 128, and is transmitted from the shaft 10 to the gear 12 integrated with the glaze 11. The rotational force transmitted to the gear 12 is transmitted to the gear portion 51) of the first movable lens barrel 5. 1st
Since the threaded portion 5a of the movable lens barrel 5 is screwed into the threaded portion 3b of the linear barrel 3, the first movement! lI]g cylinder 5 is the first group lens L
, while rotating along the optical axis. At this time,
The gear 12 is movable relative to the circumferential groove 5C of the first movable lens barrel 5 while remaining in mesh with the gear portion 5b,
Further, since the shaft 11 is movable in the axial direction relative to the shaft 10, the shaft 11 and the gear 12 move in the axial direction together with the first movable lens barrel 5 while rotating.

Autofocusing is performed by moving the first lens group L along the optical axis direction as described above.

Next, the operation when a scaling operation is performed will be explained.

GD When zooming is performed in the long focus (tele) direction.

In the state shown in FIG. 3, the camera user presses the tele button 123.
When it is pushed in, the inclined surface 119a of the movable plate 19 is pushed backward by the inclined surface 123b of the leg 123a of the tele button 123, as shown in FIG.
is moved backwards (to the right) from its position in Figure '43. When the movable plate 119 starts to move rearward, the switching gear supporting shaft 117 supported by the plate 119 and the switching gear 118 supported by the shaft 117 also start moving backward.

Note that when the movable plate 119 starts moving toward the right side, the piston 133 has the lower chamber 1 of the cylinder 132.
Because of the resistance force of the fluid in 32b, the speed of the movable plate 119 is smaller than in the case where there is no viscous resistance force generating means consisting of the piston 133 and cylinder 132. During this movement process, when the switching gear 118 and the gear 128 are still fully engaged, the first switch piece 129
The tip 129a is the tip 1 of the second switch piece 130.
30a. Switch piece 129 and switch piece 1
30 closes the switch 143 in FIG.
Prohibits driving of 04. After this, the switching gear 118 disengages from the gear 128, and after a state in which the switching gear 118 is not engaged with both the gears 128 and 115, the switching gear 1
18 moves to a position where meshing with gear 115 begins. At this time, if the teeth of the switching gear 118 and the gear 115 are out of phase, the end face of the teeth of the switching gear 118 hits the end face of the teeth of the gear 115, so the switching gear 118 receives the reaction force from the gear 115. As a result of being pushed forward in the optical axis direction, the switching gear supporting shaft 117 is also pushed forward in the optical axis direction,
Therefore, the spring 120 is compressed, and the switching gear 118 is pushed rearward in the optical axis direction with a strong force by the elastic force of the spring 120.

After that, when the tele button 123 is not completely pushed in, the conductive protrusion 125- of the variable power button support member 125 comes into contact with the conductive pattern 126a on the flexible printed board 126, and the switch 141 in Figure 3@9 is turned ON. Become. When the control circuit 140 detects that the switch 141 is turned on, the control circuit 140 starts the motor 104. The rotation of the motor 104 is caused by the pinion 105, gear 108, and gear 1.
09 to the switching gear 11B, and the switching gear 11
8 starts rotating. The switching gear 118 rotates, and the gear 1
When the phase of the teeth 18 matches the phase of the teeth of the gear 115, the switching gear 118 meshes with the gear 115 by the force of the spring 120.

After the switching gear 118 meshes with the gear 115, the driving force of the motor 104 is transmitted through the gears 105, 109, switching gear 118, gear 115, gear 110, gear 111, gear 1.
12, the signal is sequentially transmitted to the gear 116, and the shaft 15 is rotated. Then, the zoom drive ring 4 is rotated by the gear 16 in the direction of arrow C in FIG. 4, so that the photographing optical system is directed toward a long focal point as described below.

When the zoom drive ring 4 is rotated in the direction of arrow C in FIG.
a receives a rotational force from the side wall of the diagonal groove 4a, but since the linear cylinder 3 cannot rotate because the protrusion 3C fits into the axial groove 2b of the fixed cylinder 2, the protrusion 3a The force in the rotational direction applied from the diagonal groove 4a becomes a force that causes the linear cylinder 3 to move in the axial direction, and the linear cylinder 3 advances parallel to the optical axis (moves to the left D) in Fig. 5. The first movable lens barrel 5, which is in a screwed state with the linearly moving barrel 3, also moves forward together with the linearly moving barrel 3. Then, as the straight cylinder 3 moves forward from the position shown in FIG. 5, the driven roller 7 fitted into the diagonal groove 3d of the straight cylinder 3
receives a force from the linear cylinder 3 that moves relative to each other along several longitudinal directions within the diagonal groove 3d and moves in the direction of arrow E within the cam groove 2a of the fixed cylinder 2. Therefore, the second movable lens barrel 6 carrying the third group lens L3 and the fifth group lenses t and s moves forward along the optical axis while slightly rotating. The relative positional relationship between the barrel 3 and the zoom ring 4 changes from the short focus state shown in FIG. 5 to the long focus state shown in FIG. 4, and as a result, the first group lens Li and the first group lens Lens Li and the first
The group lens Li is moved.

Next, a case will be described in which a focusing operation is performed after zooming in the long focal point direction as described above.

GiD When the focusing operation is performed after the zooming operation in the tele direction 5 is completed.

When the photographer stops pushing the telephoto button 123, the movable plate 119 is pulled by the tension spring 127 and begins to move leftward from the position shown in FIGS. 10 and 11. At the same time, the tele button 123 moves the inclined surface 123b to the first position of the movable plate 119.
It begins to return to its original state due to being pushed up from the inclined surface 119ae and the restoring force of the button support member 125.

When the movable plate 119 starts moving leftward from the position shown in FIG. 10, the switching gear 118 also starts moving leftward from the position shown in FIG. In this case as well, the movable plate 119 receives a repulsive force from the fluid in the chamber 132a on the left side of the cylinder 132, so it does not move rapidly to the left, but is moved in accordance with the rate of decrease in the axial length of the chamber 132a. . When the switching gear 118 and the gear 115 are still in mesh with each other at the beginning of the movement process of the gear 11B, the first conductive protrusion 125a of the variable power button support member 125 is connected to the first conductive protrusion 125a of the flexible printed board 126. Since it is separated from the conductive pattern 126a, the switch 142 shown in FIG. 9 changes from ON to OFF. Therefore, the control circuit 140 detects that the switch 142 is OFF, and the control circuit 140 detects that the switch 142 is OFF.
In response to this, a signal is generated to stop the rotation of the motor 104, but there is a time lag from when the signal is generated until the motor 104 actually stops completely.
During that time lag, the motor is rotating.

When the movable plate 119 moves further forward, the switching gear 118 and the gear 115 are completely disengaged, and the switching gear 1
18 does not mesh with the gear 115 and the gear 128 at all, and then the chamfered portion 118a of the switching gear 118 and the gear 12
When the teeth of both gears come into contact with the chamfered portion 128a of No. 8, and the phases of the teeth of both gears match at this time, meshing of both gears is started. Note that the motor 104 is in a completely stopped state before the gear 128 and the switching gear 118 start meshing with each other.

Furthermore, the switching gear 118 moves forward, and the gear 128 and the switching gear 1
When the engagement with 18 is complete, switch piece 129
and the tip 130a of the switch piece 130.
The switch 143 in FIG. 9 changes from ON to OFF. When the control circuit 140 detects that the switch 143 is turned OFF, it disables the drive of the motor 104 and enters a state where it waits for an instruction from the main control circuit in the camera body, so that the motor 104 becomes ready for focusing drive. becomes.

Note that when focusing is performed, the operation described in the previous section (i) is performed.

qψ　When the magnification change operation is performed in the short focus direction.

When performing a zoom operation in the short focus direction, the wide button 124 is pushed in as shown in FIG.

The leg portion 124a of the wide button 124 is pushed along the second square hole 121b of the plate 121, and the inclined surface 124b moves the second inclined surface 119b of the movable plate 119 in the direction along the optical axis (right direction in Fig. 12). ) to move the movable plate 119. Therefore, the switching gear supporting shaft 117 supported on the movable plate 119 and the switching gear 118 supported on the shaft 117 also begin to move to the right from the position shown in FIG. Then, when the switching gear 118 and the gear 128 are still in mesh, the tip 129a of the switch piece 129 and the switch piece 1
30 comes into contact with the tip 130a of the switch 1 in FIG.
43 is turned on, and detecting that the switch 143 is turned on, the nine control circuit 140 prohibits driving of the motor 104.

Thereafter, the switching gear 118 disengages from the gear 128, and after passing through a state where the switching gear 118 does not mesh with either of the gears 128 and 115, the switching gear 118 moves to a position where it starts to mesh with the gear 115. At this time, if the teeth of the switching gear 118 and the gear 115 are out of phase, the switching gear 118 will be pushed forward in the optical axis direction by the reaction force from the gear 115 because it will hit the end face of the teeth of the switching gear 118. As a result, the switching gear supporting shaft 117 is also pushed forward in the optical axis direction, so that the spring 120 is compressed, and the elastic force of the spring 120 pushes the switching gear 118 backward in the optical axis direction with a strong force.

After this, when the wide button 124 is completely pushed in, the conductive protrusion 125b of the variable power button support member 125 comes into contact with the conductive pattern 126b on the flexible printed board 126, and the switch 141 shown in FIG. 9 is turned ON. When the control circuit 140 detects that the switch 141 is turned on, the control circuit 140 starts the motor 104.The rotation of the motor 104 is transmitted to the switching gear 11B via the pinion 105, gear 108, and gear 109. Switching gear 1
18 starts rotating. When the switching gear 11B rotates and the phase of the teeth of the gear 118 matches the phase of the teeth of the gear 115, the switching gear 118 meshes with the gear 115 by the force of the spring 120.

After the switching gear 118 meshes with the gear 115, the driving force of the motor 104 is transmitted through the gears 105, 109, switching gear 118, gear 115, gear 110, and gear 111.

The signal is sequentially transmitted to gear 112 and gear 116, and shaft 15 is rotated. When the zoom drive ring 4 is rotated by the gear 16 in the direction of the arrow in FIG.
Due to the fitting relationship between the protrusion 3a and the diagonal groove 4a of the ring 4, the protrusion 3a moves relatively within the groove 4a in the direction of arrow F, and the linear cylinder 3 moves backward along the optical axis ( In Fig. 4, the right direction is) moved. Therefore, the first movable lens barrel 5, which is screwed into the linear barrel 3, also moves to the right in FIG. be done. When the linear cylinder 3 moves rightward in FIG. It moves relatively in the direction of arrow H within the groove 2a. Therefore, the second movable lens barrel 6, which is integral with the driven roller 7, rotates and moves rearward (toward the right in FIG. 4), and is supported by the second movable lens barrel 6'! The J3 group lens 3 and the 5th group lens L5 move backward along the optical axis.

Through the series of operations described above, the focal length of the photographing optical system is switched from a long focus to a short focus.

(V) When the focusing operation is performed after the magnification change operation in the wide direction is completed.

When the photographer stops pressing the wide button 124, the movable plate 119 is pulled by the tension spring 127 and begins to move leftward from the position shown in FIGS. 10 and 11. At the same time, the wide button 124 begins to return to its original position due to the inclined surface 124b being pushed up by the second inclined surface 119b of the movable plate 119 and the restoring force of the variable power button support member 125.

When the movable plate 119 starts moving leftward from the position shown in FIG. 10, the switching gear 11B also starts moving leftward from the position shown in FIG. When the gear 118 and the gear 115 are still in mesh with each other, the second conductive protrusion 125b of the variable power button support member 125 is connected to the flexible printed board 12.
6, the switch 141 shown in FIG. 9 changes from ON to OFF. Therefore, the control circuit 140 detects that the switch 141 is turned off, and the control circuit 140 detects that the switch 141 is turned off.
1 is turned off, the rotation of the motor 104 is stopped. (Up to this point, the wide button 124 has been pressed and the motor 104 is rotating for zooming drive.) After the motor 104 has stopped, when the movable plate 119 moves further forward, the switching gear 11B and the gear The switching gear 118 is completely disengaged from the gear 115 and the gear 1.
28, then the chamfered portion 118a of the switching gear 118 and the chamfered portion 12Ba of the gear 12B come into contact with each other, and when the phases of the teeth of both gears match at this time, meshing of both gears is started. Then, when the switching gear 118 moves further forward and the engagement with the gear 118 becomes complete, the tip 129a of the switch piece 129 and the tip 130a of the switch piece 130 are separated, and the switch 143 in FIG.
Turns off from N. The control circuit 140 controls the switch 14
3 is turned off, the prohibition of driving the motor 104 is released and the camera enters a state of waiting for an instruction from the main control circuit in the camera body, and the motor 104 becomes in a state where it can be driven for focusing. Note that when focusing is performed, the operation described in the previous section (i) is performed.

Next, the function of the viscous resistance generating means in the operation of the switching gear as described above will be explained with reference to FIGS. 13 and 14.

As mentioned above, when the photographer stops pressing the telephoto button 123 or the wide button 124, the zoom motor 104 is stopped by the microcomputer.
Before the motor 104 actually stops completely, there is a time lag t from the time when the microcomputer stops driving the motor 104 due to idle running time due to inertia of the motor. Therefore, in the switching sequence, the time lag from when the microcomputer stops driving the motor 104 to when the switching gear 118 starts to mesh with the gear 128 has the following relationship with respect to the tIS. , a problem arises in that the focus system gear is moved after the zoom operation.

t,ll<t.

Here, regarding the time lag from when the microcomputer stops driving the motor 104 to when the switching gear 118 starts to mesh with the gear 128, cases in which there is no viscous resistance generating means and cases in which there is a viscous resistance generating means will be described.

FIG. 13 is a mechanical model diagram of the switching mechanism without viscous resistance generating means, and FIG. 14 is a mechanical model diagram with viscous resistance generating means.

In FIGS. 13 and 14, 134 is an object that moves during switching, with a total mass m, 135 is a tension spring 127 with a spring constant, and 13B is a viscous resistance generating means composed of the piston and cylinder in FIG. Attenuation coefficient C1 diagram The coordinate axes are shown in the diagram.

The equations of motion and their solutions in these two cases can be obtained by giving initial conditions that meet the desired conditions to the above equations.
The time tl, t2 (ts
) can be obtained.

Now, if we try to increase tl in the model shown in Figure 13, we can either lower the initial state kx, (initial tension) or
Alternatively, it is necessary to increase m.

However, lowering kxs (initial tension) causes the problem that switching is not performed smoothly, and there is a limit to lowering kxs (initial tension).

Furthermore, increasing m causes a problem in that the impact at the time of switching increases.

In the model shown in Figure 14, which incorporates viscous resistance, t2
In order to increase , it is sufficient to simply increase C, and kx
s (initial tension) can be set to a value that allows the switching to occur smoothly, and has the advantage that the shock at the time of switching can be alleviated because the moving speed (x) of the switching mechanism can be lowered.

In this embodiment, the viscous resistance generating means is constituted by a piston and a cylinder, but it goes without saying that various viscous damping mechanisms may be used in place of the piston and cylinder mechanism.

[Effects of the Invention] As explained above, in the lens barrel of the present invention, the process in which the switching gear moves from the meshing position with the zoom drive system gear train to the meshing position with the focus drive system gear train Since a viscous resistance generating means is provided for applying viscous resistance in a direction that impedes movement of the switching gear, the switching gear and the focus drive system gear train can be engaged after the motor has completely stopped, As a result, the focus drive system gear train malfunctioned immediately after zooming! There is no longer any fear that the focus will be shifted to A, and therefore there is no fear that the focusing accuracy will be distorted.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of a zoom lens barrel according to the present invention, and FIG. 2 is a diagram showing the lens drive mechanism of the zoom lens barrel immediately after the zooming operation is completed and when the zooming operation is not being performed. FIG. 3 is a cross-sectional view of part of the structure shown in FIG. 2 taken along the line A-A, and FIG. 5 is a developed plan view of the lens barrel portion in a short focus state, FIG. 6 is a sectional view taken along the J-J arrow in FIG. 1, and FIG.
8 is a sectional view taken along the line B-B in FIG. 1, FIG. 9 is a schematic diagram of a control system related to the lens drive mechanism of the zoom lens barrel, The figure is a developed plan view when the lens drive mechanism is performing a magnification change operation in the long focal direction, FIG. 11 is a sectional view taken along the line L-L in FIG.
Figure 2 shows the state of the zoom lens barrel when the wide button is pressed and the magnification is changed in the short focus direction, and Figures 13 and 14 include the viscous resistance generating means. FIG. 3 is a diagram showing a dynamic model of the switching mechanism. 1...Mount 2a...Cam groove 3b...Threaded portion 3d...Diagonal groove 4a...Diagonal groove 5...'! g1 moving lens barrel 6...M2 moving lens barrel L2...second group lens 2...fixed barrel 3...straight moving barrels 3a, 3c...projection 4...zoom drive ring 4b...・Gear part 5b... Gear part Ll... 1st group lens L,... 3rd group lens L4... 4th group lens LS...'s 5th group lens 7
... Driven roller 8 ... Shaft screw 9 ... Drive unit 10.11 ... Shaft 12 ... Gear
15... Axis 101... Drive unit carrying frame 104... Motor 105... Pinion 10
6...Pulse plate 107...Rotation amount detection means 1
08-112...Gear 113...Cover/bearing plate 115...Gear 116...Gear 117
...Switching gear support shaft 11B...Switching gear 119...Movable plate 120
...Spring 123...Tele button 124.
... Wide button 125 ... Magnification change button support members 125a and 125b ... Conductive protrusion 126 ... Flexible printed board 127 ... Springs 129 and 130 ... Switch piece 140 ... Lens barrel control Circuit 131...Fixed piston Rondo 132...Cylinder 133a...Fluid relief hole 33...Piston and 4 others Figure 3 Figure Figure Figure Figure Figure Figure Figure 11 Figure 2 Figure 3 Figure 4 Figure 36 4

Claims (1)

[Claims] 1. A zoom drive gear train, a focus drive gear train, a motor for supplying power to the zoom drive gear train and the focus drive gear train, and a motor for supplying power to the zoom drive gear train and the focus drive gear train; between the connected driving gear train, a first position where it meshes with the focus driving gear train and the driving gear train, and a second position where it meshes with the zoom driving gear train and the driving gear train. In a lens barrel equipped with a moving switching gear and a biasing means that constantly biases the switching gear toward the first position, the switching gear is moved to the second position by the biasing means. A lens barrel characterized in that means is provided in association with the switching gear for generating a viscous resistance force in a direction to prevent movement of the switching gear when the lens barrel is moved from the first position to the first position. .