JP2001343577A - Optical equipment and photographing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that it is difficult to add a collapsible function unless a lens barrel is made large in size, as for a fixed front lens type lens barrel, etc. SOLUTION: As for the optical equipment, plural moving element groups 1 and 2 constituting an optical system are driven in an optical axis direction by a plate cam 16 which is driven by a driving unit ZU equipped with a driving source 11, the plate cam is rotated when the driving unit is operated in 1st operation areas (a) to (b), then, plural moving element groups are driven, and the plate cam is moved in the optical axis direction when the driving unit is operated in 2nd operation areas (b) to (c) succeeding to the 1st operation area, then, plural moving element groups are driven.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens barrel and other optical equipment used for a photographing device such as a video camera.

[0002]

2. Description of the Related Art As a zoom lens for a video camera, for example, there is a zoom lens composed of four lens groups of a fixed convex, a movable concave, a fixed convex, and a movable convex in order from the subject side.

FIGS. 6A and 6B show a lens barrel structure of a general zoom lens having a four-group lens structure. (B) shows a cross section taken along line AA in (A).

The four lens groups 201a to 201d constituting the zoom lens are composed of a fixed front lens 201.
a, a variator lens group 201b that performs a zooming operation by moving along the optical axis, a fixed afocal lens 201c, and a focal plane maintenance and focusing during zooming by moving along the optical axis. And a forcing lens group 201d.

The guide bars 203, 204a, and 204b are arranged in parallel with the optical axis 205, and guide and stop the moving lens group. The DC motor 206 is a driving source for moving the variator lens group 201b.

The front lens 201a is held by the front lens barrel 202, and the variator lens group 201b is
It is held at 1. Also, the afocal lens 201
c denotes an intermediate frame 215 and a focusing lens group 201d.
Are held by the RR moving ring 214.

The front lens barrel 202 is positioned and fixed to a rear lens barrel 216. A guide bar 203 is positioned and supported by the two lens barrels 202 and 216, and a guide screw shaft 208 is rotatably supported. I have.
The guide screw shaft 208 is driven to rotate by the rotation of the output shaft 206 a of the DC motor 206 being transmitted through a gear train 207.

A V-moving ring 211 for holding the variator lens group 201b includes a pressing spring 209 and the pressing spring 20.
And a ball 210 which engages with a screw groove 208a formed in the guide screw shaft 208 by a force of 9 by the DC motor 206.
By being driven to rotate, 8 moves forward and backward in the optical axis direction while being guided and regulated by the guide bar 203.

Guide bars 204a, 204 are provided on the rear barrel 216 and the intermediate frame 215 positioned in the rear barrel 216.
04b is fitted and supported. The RR moving ring 214 can advance and retreat in the optical axis direction while being guided and rotated by the guide bars 204a and 204b.

Guide bars 204a and 204 are provided on an RR moving ring 214 for holding the focusing lens group 201d.
b is formed with a sleeve portion that is slidably fitted to the RR moving ring 2 in the optical axis direction.
14 and are integrated with each other.

The stepping motor 212 rotationally drives a lead screw 212a formed integrally with its output shaft. The RR moving ring 21 is attached to the lead screw 212a.
The RR moving ring 214 moves in the optical axis direction while being guided by the guide bars 204a and 204b by the rotation of the lead screw 212a with the engagement of the rack 213 assembled to the rack 4.

As a drive source for the variator lens group, a stepping motor may be used in the same manner as the drive source for the focusing lens group.

The front lens barrel 202, the intermediate frame 215, and the rear lens barrel 216 form a lens barrel body that substantially accommodates a lens or the like.

When the lens group holding frame is moved by using such a stepping motor, after detecting that the holding frame is located at one reference position in the optical axis direction using a photo interrupter or the like, The absolute position of the holding frame is detected by continuously counting the number of drive pulses applied to the stepping motor.

FIG. 7 shows an electrical configuration of a camera body in a conventional imaging apparatus. In this figure, FIG.
The components of the lens barrel described in FIG.
And the same reference numerals.

Reference numeral 221 denotes a solid-state imaging device such as a CCD;
Denotes a drive mechanism of the variator lens group 201b, and includes a motor 206 (or a stepping motor), a gear train 207.
And a guide screw shaft 208 and the like.

Reference numeral 223 denotes a focusing lens group 201d.
And includes a stepping motor 212, a lead screw shaft 212a, a rack 213, and the like.

Reference numeral 224 denotes a drive mechanism of the diaphragm device 235 disposed between the variator lens group 201b and the afocal lens 201c.

Reference numeral 225 denotes a zoom encoder, and 227 denotes a focus encoder. Each of these encoders detects the absolute position of the variator lens group 201b and the focusing lens group 201d in the optical axis direction. When a DC motor is used as the variator driving source as shown in FIG. 11, an absolute position encoder such as a volume is used, or a magnetic type is used.

When a stepping motor is used as a drive source, a method of continuously counting the number of operation pulses input to the stepping motor after arranging the holding frame at the reference position as described above is used. General.

Reference numeral 226 denotes an aperture encoder, which employs a system in which a Hall element is disposed inside an aperture drive source 224 such as a motor and detects the rotational positional relationship between a rotor and a stator.

A CPU 232 controls the camera. A camera signal processing circuit 228 performs predetermined amplification, gamma correction, and the like on the output of the solid-state imaging device 221. The contrast signal of the video signal that has undergone these predetermined processes passes through the AE gate 229 and the AF gate 230. That is, the optimum signal extraction range for exposure determination and focusing is set by this gate in the entire screen. The size of this gate is variable,
There may be a case where a plurality is provided.

Reference numeral 231 denotes an AF signal processing circuit which processes an AF signal for AF (auto focus), and generates one or a plurality of outputs related to a high frequency component of a video signal. 233 is a zoom switch, and 234 is a zoom tracking memory. Zoom tracking memory 234
Stores information on the focusing lens position to be set in accordance with the subject distance and the variator lens position during zooming. Note that C is used as the zoom tracking memory.
The memory in the PU 232 may be used.

For example, the photographer sets the zoom switch 23
3 is operated, the CPU 232 determines the current variator as a detection result of the zoom encoder 225 so that the predetermined positional relationship between the variator lens and the focusing lens calculated based on the information of the zoom tracking memory 234 is maintained. The absolute position in the optical axis direction of the lens and the calculated position of the variator lens to be set, and the current absolute position of the focus lens in the optical axis direction as a detection result of the focus encoder 227 and the calculated focus lens should be set. The drive of the zoom drive mechanism 222 and the focussing drive mechanism 223 is controlled so that the positions match each other.

In the auto focus operation, the CPU 2 sets the output of the AF signal processing circuit 231 to a peak so that
Reference numeral 32 controls the driving of the focusing drive mechanism 223.

Further, in order to obtain an appropriate exposure, the CPU 2
Reference numeral 32 designates the average value of the output of the Y signal passing through the AE gate 229 as a predetermined value, and controls the driving of the aperture driving source 224 so that the output of the aperture encoder 226 becomes the predetermined value, thereby controlling the aperture diameter.

[0027]

However, in recent years, the photographing lens has been required to be reduced in size and diameter, and from the object side, which is an optical type which has been most often used as a zoom lens for a video camera. In the optical type composed of four lens groups of a fixed convex, a movable concave, a fixed convex, and a movable convex in order, the front lens is fixed,
There is a problem that the total length of the lens barrel holding the optical system becomes long.

Therefore, a front lens position variable zoom optical type has been proposed in which the front lens is retracted (stored) with respect to the camera body when stored, or the front lens position is variable at the wide end.

However, since the above-mentioned collapsible lens barrel and the lens barrel structure of the front lens position variable type use a helicoid or the like, the lens barrel structure becomes complicated and large, and the number of parts increases, resulting in an increase in cost. is there.

When a helicoid is not used, driving is performed by a lead screw and a rack member formed of a movable group. In this case, when an external force or the like is applied to the front lens group, the front lens group is formed. There is a possibility that the rack which has been shifted from a regular position on the lead screw to another position, that is, a so-called rack shift may occur. When this rack shift occurs, the positional information of the front lens group is destroyed, and the front lens group and the focus lens group are controlled so as to have a desired lens interval at all focal lengths, thereby maintaining a focused state. However, in order to recover the trouble, the power must be turned on once and the initial position confirmation operation must be performed.

Therefore, the present invention makes it possible to drive and store the moving element group in the use area by a simple cam mechanism, to prevent rack displacement even when an external force or the like is applied to the front lens, and to release the external force. It is an object of the present invention to provide a compact optical device that can secure a focused state later.

[0032]

In order to achieve the above object, according to a first aspect of the present invention, a plurality of moving element groups constituting an optical system are formed by a plate cam driven by a drive unit having a drive source. An optical device driven in an optical axis direction, wherein the plate cam rotates to drive a plurality of moving element groups when the drive unit operates in a first operation area, and the drive unit is configured to drive the first unit. It is configured to move in the optical axis direction and drive a plurality of moving element groups when operating in a second operation area that is continuous with the operation area.

Thus, without using a member such as a helicoid or a cam ring, which increases the size (larger diameter) of the device,
With a simple mechanism consisting of one drive unit and a plate cam,
It becomes possible to drive the plurality of moving element groups in the optical axis direction.

In the second invention of the present application, an optical apparatus for driving the first and second moving element groups constituting the optical system in the optical axis direction by a plate cam driven by a drive unit having a drive source. The plate cam rotates to drive the first and second moving element groups in directions opposite to each other when the drive unit operates in the first operation region, and the drive unit operates in the first operation region. When operating in the second operation region that is continuous with the region, the first and second moving element groups are moved in the optical axis direction to move in the same direction as each other.

With this arrangement, a complicated mechanism, such as driving the first and second moving element groups in directions opposite to each other or in the same direction, with a simple mechanism similar to the first aspect of the invention. The moving element group can be driven.

In the first and second aspects of the present invention, the plurality of moving element groups are driven in a use area for photographing or the like by operating the drive unit in the first operation area, while the second operation area is operated. By driving the plurality of moving element groups (particularly, the moving element group located closest to the object side) in the storage area by operating the device, it is possible to provide a compact optical device when carrying the device.

A light amount adjustment unit may be provided in one of the plurality of moving element groups to increase the degree of freedom in optical arrangement and to reduce the size of the optical system.

When one of the plurality of moving element groups is the moving element group closest to the object, this moving element group is
By applying a spring bias from the image plane side to the cam portion of the plate cam, when an external force or the like from the object side is applied to this movable element group, the movable element group is opposed to the spring bias force by the cam portion. It is possible to prevent the external force or the like from being transmitted to the plate cam and the drive unit by being disengaged from the plate, and when the external force or the like disappears, the moving element group comes into contact with the cam portion again by the spring biasing force. Optical performance is guaranteed.

[0039]

FIG. 1 shows an optical system of a zoom lens for a video camera according to an embodiment of the present invention.
FIG. 2 shows a configuration of a lens barrel (optical apparatus) in which the optical system of FIG. 1 is arranged. FIG. 3 shows a plate cam mechanism in the lens barrel, and FIG. 4 shows a cross section when the lens barrel is cut along a line AA in the figure. FIG. 5 shows the configuration of a zoom motor unit used for the lens barrel.

In FIG. 1, L1 is a first lens unit (first lens unit).
Moving lens group: zoom lens group).
L2 denotes a second group lens (second moving element group: correction lens group), which is a concave lens that moves in the opposite direction to the first group lens L1 during zooming to correct a focus movement accompanying the movement of the first group lens L1. It is.

L3 is a convex lens as a fixed third group lens, L4 is a convex lens as a fourth group lens for performing focus adjustment, and I is an aperture unit (light amount adjustment unit). FIG. 1 shows a telephoto state, a wide state, and a collapsed (retracted) state from above, and zooming from telephoto to wide as indicated by the arrow moves the first lens unit L1 toward the image plane side to move the second lens unit L2 toward the image plane. The lens group L2 is a subject (object)
Move to the side. When the photographing is not performed, the first and second lens units L1 and L2 are moved to the collapsed state.
Move to the image plane side while maintaining substantially the same interval.

Next, a configuration for driving the above optical system will be described. 2 and 4, reference numeral 1 denotes a first group lens L.
1 shows a first-group lens barrel that holds 1. The first lens barrel 1 is held by two guide bars 6a and 6b (see FIG. 3) so as to be movable in the optical axis direction. 2 is a second group lens L2
Is shown, and is held movably in the optical axis direction by two guide bars 7a and 7b (see FIG. 3), similarly to the first lens barrel 1.

Reference numeral 3 denotes an afocal lens barrel holding the third lens unit L3, which is sandwiched by a rear lens barrel 8 holding a fixed lens barrel 5 and a low-pass filter L5 and fixed by screws (not shown).

A CCD (not shown) is provided at the rear of the rear lens barrel 8.
Sensor is attached. Reference numeral 4 denotes a fourth-group lens barrel that holds the fourth group lens L4, and is movably held in the optical axis direction by a guide bar 7b and a guide bar 9 common to the second-group lens barrel 2.

The guide bars 6a, 6b, 7a, 7b are held at both ends by the fixed lens barrel 5 and the rear lens barrel 8, and the guide bar 9 is held at both ends by the afocal ring 3 and the rear lens barrel 8. ing. By these five guide bars, 1
The guides in the optical axis direction of the group lens barrel 1, the group two lens barrel 2, and the group four lens barrel 4 and detent around the guide bar are performed.

Reference numeral 10 denotes an IG meter for driving the aperture blades by an electromagnetic actuator, which is fixed to the afocal ring 3 sandwiched between the fixed lens barrel 5 and the rear lens barrel 8 by screws (not shown). The fixed lens barrel 5, the rear lens barrel 8, and the afocal ring 3 constitute a lens barrel (device) body.

Reference numeral ZU denotes a zoom motor unit (drive unit). As shown in FIG. 5, a substantially U-shaped holding plate 12 causes a zoom motor 11 which is a stepping motor as a drive source and an output shaft of the motor 11 to be driven. And a screw shaft 13 integrated with the lens barrel, and is fixed to the fixed barrel 5 with screws.

A guide shaft 13 extending parallel to the screw shaft 14 is attached between both ends of the holding plate 12, and a carriage 15 is fitted on the guide shaft 13 so as to be movable in the axial direction.

The carriage 15 is provided with a rack 15a that meshes with the screw shaft 14. When the zoom motor 11 operates and the screw shaft 13 rotates, the carriage 15 is driven in the optical axis direction by the feed screw action between the screw shaft 13 and the rack portion 15b. The carriage 15 is provided with a connecting pin 15a that engages with a connecting long groove 16e formed in the carriage 15 and a plate cam 16 described later. For this reason, the plate cam 16
Receives the driving force in the optical axis direction from the zoom motor unit ZU via the carriage 15.

A cam follower 1a is formed in the first lens barrel 1. The position of the cam follower 1a, which is in contact with a first cam portion 16d formed on the plate cam 16, is displaced as the plate cam 16 rotates. The first lens barrel 1 is driven in the optical axis direction. Similarly,
A cam follower 2a is also formed in the second lens barrel 2.
The second group barrel 2 is driven in the optical axis direction by the displacement of the contact position between the plate cam 16 and the second cam portion 16f formed as the plate cam 16 rotates.

FU (see FIG. 3) is a focus motor unit. The focus motor 18 as a stepping motor and the screw shaft 18a integrated with the output shaft of the motor 18 are held by a substantially U-shaped holding plate 18b. It is held and configured, and is fixed to the rear barrel 8 with screws.

A rack 19 that meshes with the screw shaft 18a is attached to the fourth lens barrel 4. When the focus motor 18 operates and the screw shaft 18a rotates,
The fourth group barrel 4 is driven in the optical axis direction by the feed screw action between the screw shaft 18a and the rack 19.

The rack 19 is urged by a spring 20 in a direction in which it engages with the screw shaft 18a and in a direction in which it is pressed against the fourth lens barrel 4 in the optical axis direction. The play of the engagement with the lens 18a and the thrust play with respect to the fourth lens barrel 4 are removed.

The rack 19 is provided with shaft portions 19a, 19b.
Is fitted to the fourth lens barrel 4 by fitting it into a hole 4a formed in the fourth lens barrel 4 so as to extend in the optical axis direction, and is fitted in a plane orthogonal to the optical axis about the shaft parts 19a and 19b. Is rotatable. For this reason, the guide bars 7 b and 9 for guiding the fourth lens barrel 4 in the optical axis direction and the screw shaft 18 are provided.
Even if there is a deviation in the degree of parallelism with a, smooth driving in the optical axis direction of the fourth lens barrel 4 is ensured.

Reference numeral 16 denotes a plate cam formed by forming the first and second cam portions 16d and 16f and the connecting long groove 16e on a plate-like member. Between the portions where the cam portions 16d and 16f are formed, a linear long groove portion 16a and this long groove portion 16a are formed.
The guide groove is formed by an arcuate groove portion 16c branching from the middle position of a. These guide grooves 16a, 16c
A first fixed pin 3a and a second fixed pin 3b provided integrally with the afocal ring 3 are engaged with the first ring.

As shown in FIG. 2A, the first fixing pin 3
a contacts the image surface side end 16g of the long groove portion 16a and the second fixing pin 3b is engaged with the arc groove portion 16c.
When the plate cam 16 receives a driving force in the optical axis direction from the carriage 15, the plate cam 16 rotates about the first fixed pin 3a while being guided by the second fixed pin 3b. In addition,
The rotation range of the plate cam 16 is determined by the second fixing pin 3b, the tip of the arc groove portion 16c, and the width direction end 16i of the long groove portion 16a.
Limited by contact with

As shown in FIGS. 2B and 2C,
When the plate cam 16 receives a driving force in the optical axis direction from the carriage 15 when both the first fixing pin 3a and the second fixing pin 3b are engaged with the long groove portion 16a, the plate cam 16
Moves in the optical axis direction while being guided by the fixing pins 3a and 3b. The range of movement of the plate cam 16 in the optical axis direction is determined by the first fixed pin 3a and the image surface side
6g and the second fixing pin 3b and the long groove portion 16a
Is limited by contact with the subject side end 16b.

The plate cam 16 has a sliding surface 1b formed at the root of the pin 1a of the first lens barrel 1 and a sliding surface 2 formed at the root of the pin 2a of the second lens barrel 2.
The movement toward the lens barrel inner diameter side is prevented by b.

Also, as shown in FIG. 4, after the plate cam 16 is installed, the fixed lens barrel 5 is installed, so that the plate cam 16 is formed at two convex portions formed on the inner peripheral surface of the fixed lens barrel 5. 5a, the plate cam 16 is slidably contacted, and the plate cam 16 is prevented from moving toward the outer diameter side of the lens barrel. Sliding surfaces 1b, 2b and convex portion 5a
A gap is provided between the first and second positions so that the plate cam 16 can smoothly rotate or move in the optical axis direction.

The first lens barrel 1 and the second lens barrel 2 are urged from the image plane side to the object side by coil springs 17a, 17b arranged on the outer periphery of the guide bars 6b, 7b, respectively. , Each cam follower 1
a, 2a are the first and second cam portions 16 of the plate cam 16;
d, 16f. This urges forward and eliminates contact play between the cam followers 1a and 2a and the first and second cam portions 16d and 16f of the plate cam 16, and from a wide state to a tele state described later. Between the first fixing pin 3a and the image surface side end 16g of the long groove portion 16a can be eliminated. The first and second lens barrels 1 and 2 are provided with coil springs 17a and 17b so that the load on the zoom motor 11 is not increased and the contact backlash can be eliminated in any lens barrel position. The spring pressure is set to such a level as to lift against its own weight.

Next, the operation in the zoom region (use region) and the operation in the collapsed region (storage region) of the lens barrel of this embodiment will be described.

First, in order to shift the lens barrel from the telephoto end state to the wide end state, the zoom motor unit ZU is moved from the position shown in FIG. 2A to the position shown in FIG. When operated to move (operate in the first operation area), the plate cam 16 is moved via the carriage 15.
The first fixed pin 3a abuts on the image side end 16g of the long groove portion 16a, and the second fixed pin 3b engages with the arc groove portion 16c. Therefore, the plate cam 16 rotates counterclockwise around the first fixing pin 3a while being guided by the second fixing pin 3b.

The rotation of the plate cam 16 causes the first group lens barrel 1 urged toward the subject side by the coil spring 17a to displace the contact position of the cam follower 1a with the cam portion 16d of the plate cam 16. By doing so, it moves to the image plane side. Further, the second group barrel 2 urged toward the subject by the coil spring 17b moves the first group barrel 1 by displacing the contact position of the cam follower 2a with the cam portion 16f of the plate cam 16. It moves to the opposite side, that is, the subject side.

When the wide end state is reached, the second fixing pin 3b abuts on the widthwise end surface 16i of the long groove portion 16a of the plate cam 16, and further rotation of the plate cam 16 in the counterclockwise direction is prevented. You. At this time, the long groove portion 16a is substantially parallel to the optical axis.

Then, the zoom motor unit ZU is moved further in the same direction, that is, the carriage 15 is moved from the position shown in FIG. 2B to the position shown in FIG. 2C (in the second operation area). Operation), the carriage 1
5, a driving force to the image surface side acts on the plate cam 16, but the plate cam 16 whose rotation is prevented by the second fixing pin 3b is elongated by the first and second fixing pins 3a and 3b. The portion 16a moves to the image plane side together with the carriage 15 while being guided.

As the plate cam 16 moves toward the image plane, the first and second lens barrels 1 and 2 are moved by the coil springs 17.
It is driven integrally with the plate cam 16 to the image plane side while maintaining the interval in the wide end state against the urging forces of a and 17b. Then, when the second fixing pin 3b abuts on the subject side end 16b of the long groove portion 16a, further movement of the plate cam 16 to the image surface side is prevented, and reaches the collapsed end. In this retracted end state, the first lens barrel 1 is stored so as not to protrude from the lens barrel main body.

On the other hand, when the zoom motor unit ZU is operated in the opposite direction (operates in the second operation area) to drive from the retracted end state to the wide end state, the plate cam 16, the first group and the second group barrel 1 are operated. , 2 are integrally extended toward the subject.
Then, the first fixing pin 3a is connected to the long groove portion 16 of the plate cam 16.
When a is abutted on the image surface side end 16g, further movement to the subject side is prevented, and the wide end state is set.

Further, when the zoom motor unit ZU is continuously operated in the reverse direction and the carriage 15 is moved from the position shown in FIG. 2B to the position shown in FIG.
The plate cam 16 whose parallel movement from the position in the wide end state to the subject side is prevented by the first fixing pin 3a,
It rotates around the fixing pin 3a. Coil spring 17
The first-group barrel 1 urged toward the subject by a moves to the subject side when the contact position of the cam follower 1a with the cam portion 16d of the plate cam 16 is displaced.
The second lens barrel 2 urged toward the subject by the coil spring 17b is a plate cam 1 of the cam follower 2a.
When the contact position of the first lens unit 6 with the cam portion 16f is displaced, the first lens unit 1 moves to the opposite side to the moving direction of the first lens barrel 1, ie, to the image plane side.

The light shielding portion 16h formed near the tip of the first cam portion 16a of the plate cam 16 is located at the position where the plate cam 16 is located at the position shown in FIG. 2B or at the position shown in FIG. Then, the light enters between the light emitting element and the light receiving element of the photo interrupter (not shown) fixed to the lens barrel main body. Thus, it is detected that the plate cam 16 is located at the reference position, and thereafter, the position of the plate cam 16 can be detected by counting the number of pulses input to the zoom motor 11.
Since the positions of the first-group barrel 1 and the second-group barrel 2 are determined in conjunction with each other by the plate cam 16, if the position of the plate cam 16 is detected, both the zoom position and the retracted position can be detected.

A similar light-shielding wall 4b is also formed on the fourth-group barrel 4, and the fourth-group barrel 4 is located at the reference position by being inserted between the light-emitting element and the light-receiving element of the interrupter (not shown). Is detected. Thereafter, the position of the fourth lens barrel 4 can be detected by counting the number of pulses input to the focus motor 14.

As described above, according to the present embodiment, one plate cam 16 is provided, and the plate cam 16 is given a simple configuration in which only one zoom motor unit ZU applies a driving force in the optical axis direction. The two moving element groups can be driven in the optical axis direction. In addition, at the time of zoom operation, the first lens barrel 1
And the second lens barrel 2 are moved in opposite directions,
In the collapsible region, the same complicated driving as in the case of using a cam ring, such as moving the first lens barrel 1 and the second lens barrel 2 in the same direction while maintaining the body distance substantially, is possible.

Further, in the retracted state, since the first lens barrel 1 is housed in the lens barrel main body, the total length of the lens barrel is shortened, and it is convenient for carrying around.

In addition, compared to the case where a cam ring or a helicoid ring is used, it is easier to reduce the size, and the load torque of the motor 11 can be reduced, so that the power consumption can be reduced. Furthermore, since only one plate cam 16 is provided, the assemblability of the lens barrel is good, and the cost can be reduced.

In this embodiment, when an external force or the like acts on the first lens barrel 1 from the object side during the telephoto end state to the wide end state, the first lens group barrel 1 is driven by the coil spring 17a.
Moves to the image surface side against the urging force of. At this time, the cam follower 1a of the first lens barrel 1 is the first cam portion 1 of the plate cam 16.
6d, the external force or the like is not transmitted to the plate cam 16, the carriage 15, and the zoom motor unit ZU.
Therefore, the engagement position of the rack portion 15b of the carriage 15 with the screw shaft 13 does not shift due to an external force or the like acting on the first lens barrel 1.

On the other hand, when the external force acting on the first lens barrel 1 disappears, the first lens barrel 1 is pushed back to the subject side by the urging force of the coil spring 17a, and the cam follower 1a of the first lens barrel 1 again. Abuts against the first cam portion 16d of the plate cam 16. Therefore, optical performance thereafter is guaranteed.

In the above embodiment, the case where the stepping motor is used as the driving source has been described. However, similar effects can be obtained by using another DC motor, a linear actuator, or the like. This embodiment is also related to position detection with an optical detection means (photo interrupter).
Has been described, but other detection means such as a magnetic type and a variable resistance type may be used.

Further, in the above embodiment, the first and second lens groups are moved, and the lens barrel is of an optical type in which the stop position is fixed. However, the present invention is directed to changing the shape of the cam portion of the plate cam. The present invention is also applicable to an optical lens barrel in which the first and second lens groups and the aperture position are variable. further,
By changing the shape of the cam portion of the plate cam, the first and second lens groups may be driven in the same direction in the zoom region and the collapsed region.

Further, by forming the cam portion for the first group of the plate cam into an R shape centering on the fixing pin on the afocal ring, the position of the first group on the optical axis is not changed in the photographing area. It is also possible to perform only the collapsing operation, and it is possible to add a collapsing function to the conventional so-called four-group rear focus optical system fixed to the front lens.

In the above embodiment, the lens barrel for a video camera has been described. However, the present invention can be applied to an optical apparatus having another optical system.

[0080]

As described above, according to the first aspect of the present invention, one drive unit and one plate cam can be used without using a member such as a helicoid or a cam ring, which causes an increase in size (increase in diameter) of the device. , A plurality of moving element groups can be driven in the optical axis direction.

According to the second aspect of the present invention, the first aspect
With the simple mechanism as in the invention of the third aspect, it is possible to drive the complex moving element group such as driving the first and second moving element groups in opposite directions or in the same direction.

In the first and second aspects of the present invention, the plurality of moving element groups are driven in the use area for photographing or the like by operating the drive unit in the first operation area, while the second operation area is operated. By driving the plurality of moving element groups (particularly, the moving element group located closest to the object side) in the storage area by operating the device, a compact optical device can be obtained when the portable device is carried.

Further, if one of the plurality of moving element groups is a light amount adjusting unit, the degree of freedom of arrangement of the light amount adjusting unit can be increased, and the size of the optical system can be reduced.

If one of the plurality of moving element groups is the moving object group closest to the object, this moving element group is
If the cam portion of the plate cam is spring-biased from the image plane side, when an external force or the like from the object side is applied to the moving element group, the moving element group opposes the spring urging force. It is possible to prevent the external force or the like from being separated from the cam portion and transmitted to the plate cam and the drive unit. Then, when the external force or the like disappears, the moving element group can be brought into contact with the cam portion again by the spring urging force, and the optical performance can be guaranteed.

Furthermore, if the cam portion for the moving element group closest to the object side in the plate cam is formed in an R shape around the rotation axis of the plate cam, for example, the optical axis of the moving element group in the use area The optical axis direction movement can be performed only in the collapsible region without changing the direction position, and a collapsible function can be added to a so-called front lens fixed rear focus optical system.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an arrangement configuration of an optical system suitable for implementing the present invention.

FIG. 2 is a cross-sectional view of a lens barrel as an embodiment of the present invention having the optical system.

FIG. 3 is an exploded perspective view of a main part of a drive mechanism in the lens barrel.

FIG. 4 is a cross-sectional view of the lens barrel of FIG. 2 cut along AA.

FIG. 5 is an exploded perspective view of a zoom motor unit used for the lens barrel.

FIG. 6 is a sectional view of a conventional lens barrel.

FIG. 7 is a block diagram showing a control circuit in a conventional lens barrel.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 first lens barrel 1a cam follower 2 second lens barrel 2a cam follower 3 afocal ring 3a, 3b fixing pin 4 fourth lens barrel 5 fixed lens barrel 6a, 6b, 7a, 7b, 9 guide bar 8 rear lens barrel 10 IG meter 11 Zoom motor 13, 18a Screw shaft 14 Guide shaft 15 Carriage 15a Connection pin 15b Rack 16 Plate cam 16a Long groove 16c Arc groove 16d First cam 16e Long groove 16f Second cam 17a, 17b Coil spring 18 Focus Motor 19 Rack 20 Spring

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Tadanori Okada 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term in Canon Inc. (reference) 2H044 BD06 BD11 BD16 BE03 BE08 BF04 EF04 EF07 EF10 2H087 KA03 MA18 RA32 SA13 SA17 SA19 SA62 SA63 SA74 2H101 BB07 DD41 DD44 DD55 DD62

Claims (19)

[Claims] 1. An optical apparatus for driving a plurality of moving element groups constituting an optical system in an optical axis direction by a plate cam driven by a drive unit having a drive source, wherein the plate cam includes the drive unit. Rotates when operating in the first operating area to drive the plurality of moving element groups,
A second drive unit connected to the first operating area;
An optical device that moves in the optical axis direction to drive the plurality of moving element groups when operating in the operation region of (1). 2. The drive unit according to claim 1, wherein the drive unit includes a drive source having a screw shaft extending in an optical axis direction, and a rack member meshed with the screw shaft and connected to the plate cam. The optical device according to claim 1. 3. The optical apparatus according to claim 1, wherein the driving source is a stepping motor. 4. The apparatus according to claim 1, wherein the plurality of moving element groups include a variable power lens group and a correction lens group for correcting a focus movement due to the movement of the variable power lens group. An optical device according to any of the claims. 5. The optical apparatus according to claim 1, wherein the plurality of moving element groups include a light amount adjustment unit. 6. The driving unit applies a driving force in an optical axis direction to the plate cam by operating in the first and second operation regions, and the plate cam has a linear shape. An apparatus main body including a guide portion including a long groove portion and an arc groove portion branching from the middle of the long groove portion and extending therefrom; and a cam portion for cam driving the first and second moving element groups, respectively. Alternatively, first and second pins respectively engaging with the guide portion are formed on a member fixed to the device main body, and when the drive unit operates in the first operation region, the long groove is formed. The first pin is engaged with the end of the portion, and the second pin is engaged with the arc groove portion to allow the plate cam to rotate around the first pin. The cam section is moved forward by the rotation of the cam. When the plurality of moving element groups are driven, and when the drive unit operates in the second operation area, the first and second pins engage with the long groove portion extending in the optical axis direction, and the plate is moved. 6. The optical device according to claim 1, wherein the cam is allowed to move in the optical axis direction, and the cam portion drives the plurality of moving element groups by moving the plate cam in the optical axis direction. machine. 7. The driving unit is operable in the first operating area, wherein the plurality of moving element groups can be moved in a use area that can be used for photographing or the like and a storage area that is stored in a device body. In this case, the plurality of moving element groups move in the use area, and when the drive unit operates in the second operation area, the plurality of moving element groups move in the storage area. The optical device according to claim 1. 8. One of the plurality of moving element groups is a moving element group closest to the object side of the optical system, and the moving element group closest to the object side is an image plane side on a cam portion of the plate cam. The optical device according to any one of claims 1 to 7, wherein the optical device is abutted by being biased by a spring. 9. One of the plurality of moving element groups is a moving element group closest to the object side in the optical system, and a cam portion of the plate cam that comes into contact with the moving object group closest to the object side is The optical device according to any one of claims 1 to 8, wherein the optical device is formed in an arc shape about a rotation axis when the plate cam rotates. 10. An optical apparatus for driving a first and a second moving element group constituting an optical system in a direction of an optical axis by a plate cam driven by a drive unit having a drive source, wherein the plate cam is Rotating when the drive unit operates in the first operation area to drive the first and second moving element groups in opposite directions, and the drive unit continues to the first operation area. An optical apparatus characterized by moving in the optical axis direction to move the first and second moving element groups in the same direction when operating in a second operating area. 11. The drive unit comprises a drive source having a screw shaft extending in an optical axis direction, and a rack member meshed with the screw shaft and connected to the plate cam. The optical device according to claim 1. 12. The optical apparatus according to claim 10, wherein the drive source is a stepping motor. 13. The first and second moving element groups,
13. The optical apparatus according to claim 10, wherein the optical apparatus is a variable power lens group and a correction lens group for correcting a focus movement due to the movement of the variable power lens group. 14. The optical apparatus according to claim 10, wherein one of the first and second moving element groups is a light amount adjusting unit. 15. The driving unit applies a driving force in the optical axis direction to the plate cam by operating in the first and second operation regions. The plate cam has a linear shape. An apparatus main body including a guide portion including a long groove portion and an arc groove portion branching from the middle of the long groove portion and extending therefrom; and a cam portion for cam driving the first and second moving element groups, respectively. Alternatively, first and second pins respectively engaging with the guide portion are formed on a member fixed to the device main body, and when the drive unit operates in the first operation region, the long groove is formed. The first pin is engaged with the end of the portion, and the second pin is engaged with the arc groove portion to allow the plate cam to rotate around the first pin. The rotation of the cam causes the cam parts to move The first and second moving element groups are driven in directions opposite to each other, and when the drive unit operates in the second operation area, the first and second grooves are extended into the long groove portion extending in the optical axis direction. Are allowed to move in the optical axis direction of the plate cam, and the cam portion drives the first and second moving element groups in the same direction with each other by the optical axis direction movement of the plate cam. The optical device according to claim 10, wherein: 16. The first and second moving element groups can be moved in a use area that can be used for photographing or the like and a storage area that is stored in a device main body, and the drive unit is configured to perform the first operation. When operating in the area, the first and second moving element groups move in the use area, and when the drive unit operates in the second operating area, the first and second moving elements. 16. The optical device according to claim 10, wherein a group moves in the storage area. 17. One of the first and second moving element groups is a moving element group closest to an object in the optical system, and the moving element group closest to the object is a cam portion of the plate cam. The optical device according to claim 10, wherein the optical device is abutted against the lens by a spring from the image surface side. 18. One of the first and second moving element groups is a moving element group closest to the object side in the optical system, and the plate cam has an image plane side of the moving element group closest to the object side. The optical device according to any one of claims 10 to 17, wherein the cam portion contacting the plate cam is formed in an arc shape centered on a rotation axis when the plate cam rotates. 19. A photographing apparatus comprising the optical device according to claim 1. Description: