JPH10282394A - Zoom lens device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact zoom lens device by reducing the length along the optical axis direction of a lens barrel. SOLUTION: First cam grooves 33-35 to move a first lens holding frame along the predetermined locus of variable power and a second cam groove 42 to move a second lens holding frame along the different locus of variable power different from that of the first lens group are formed on an inner circumferential surface of a rotary cylinder 13 in a partially intersected manner. A first cam pin 40 provided on the first lens holding frame and a second cam pin 45 provided on the second lens holding frame are respectively engaged with the first cam grooves 33-35 and the second cam groove 42. The first cam groove 35 is shallower than the second cam groove 42, and divided at the intersection area. When the first cam pin 40 is moved to the intersection area G1, an auxiliary pin 50 provided on the first lens holding frame is engaged with guide projection pairs 55, 56 projected on the inner circumference of the rotary cylinder 13, and the first cam pin 40 is guided so as to be moved along the locus of the first cam groove 35.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zoom lens device used for an electronic still camera, a television camera, a photographic camera and the like, and more particularly to a zoom lens device having at least two lens groups. .

[0002]

2. Description of the Related Art Conventionally, a zoom lens device has a front lens unit having a negative power and a rear lens unit having a positive power in order to achieve a compact and high zoom magnification. Things are known. In this type, a first cam means for moving the front group lens along a predetermined variable power locus, and a second cam means for moving the rear group lens along a variable power path different from the first lens group The front lens group and the rear lens group are incorporated in a cam barrel having the following.

The deployed shape of the first cam means is such that the front group lens is moved to the object side at the wide end, and is moved to the image plane at the tele end. The deployed shape of the second cam means is such that the rear group lens is moved to the image plane side at the wide end, and is moved to the object side at the tele end. Therefore, in the movement of the lens at the time of zooming, the distance between the front group lens and the rear group lens is the longest at the wide end, and the distance between the front group lens and the rear group lens is the shortest at the telephoto end.

As is well known, the cam means includes a cam pin provided on the lens frame, a cam barrel having a cam groove into which the cam pin is fitted, and a linear guide for restricting the rotation direction of the lens frame. The lens frame advances and retreats in the optical axis direction due to the relative rotation between the cam barrel and the linear guide. The amount of displacement in the optical axis direction relative to the amount of rotation is the amount of movement of the lens.

[0005]

In order to improve the magnification of a zoom lens apparatus of the type described above, it is necessary to increase the displacement of the cam groove in the optical axis direction by a predetermined amount of rotation. As a result, the length of the cam barrel in the optical axis direction increases. For this reason, if two cam means are provided side by side along the optical axis direction, the length of the cam barrel along the optical axis direction is further increased, and when a thin camera is used, the lens barrel projects from the body. When the lens barrel is housed in the body, the thickness of the body is increased.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has been devised so as to minimize the length of the lens barrel in the optical axis direction, which is an obstacle to improving the magnification. It is an object to provide a lens device.

[0007]

In order to solve the above-mentioned problems, according to the present invention, the first cam groove and the second cam groove intersect and the first or second lens holding frame has the first or second lens holding frame.
An auxiliary pin protrudes from a position different from the cam pin, and engages with the auxiliary pin when the first or second cam pin passes through the intersection area between the first cam groove and the second cam groove to engage with the first or second lens. The cam barrel is provided with guide means for guiding the holding frame to move along the locus of the first or second cam groove. The cam barrel has a first cam groove for moving at least two lens groups constituting the zoom lens in the optical axis direction and a second cam groove.
A cam groove is provided. These cam grooves intersect at least at one point. When the first or second cam pin passes through the intersection of the first cam groove and the second cam groove, the auxiliary pin engages with the guide means provided on the cam cylinder,
The first or second lens holding frame is guided along the locus of the first or second cam groove.

When the first and second cam grooves have the same depth, it is necessary to provide two pairs of auxiliary pins and guide means. This is because, when the first cam pin passes through the intersection, the first guide means for engaging the first auxiliary pin provided on the first lens holding frame at a position different from the first guide pin, and the second cam pin When you cross the intersection,
The second guide means engages with a second auxiliary pin provided on the second lens holding frame at a position different from the guide pin.

However, instead of providing two pairs of auxiliary pins and guide means, the second cam groove is formed deeper than the first cam groove, as described in the second aspect of the present invention.
If the second cam pin is allowed to pass through the intersection while maintaining the engagement with the second cam groove, it is only necessary to provide a pair of the auxiliary pin and the guide means. According to the third aspect of the present invention, the first and second cam grooves have a retracted area for moving the first and second lens holding frames from the effective magnification range to the inside of the camera body. Is provided with an intersection area.

[0010]

FIG. 1 shows a zoom lens apparatus to which the present invention is applied. In this zoom lens device, the photographing lens includes a first lens unit 1 having a negative power in order from the object side.
This is a three-unit zoom lens composed of 0, a second lens unit 11 having positive power, and a third lens unit 12 having positive power, and is mainly used for an electronic still camera. The configuration of the apparatus includes a cam barrel 13, an outer fixed barrel 14, an inner fixed barrel 15, a moving barrel 16, a second lens frame 17, a third lens frame 18, and the like.

The outer fixed cylinder 14 is fixed to a camera body or the like, and the entire length along the direction of the optical axis 20 is housed inside the camera body. The inner fixed cylinder 15 is inserted into the outer fixed cylinder 14 with a gap, and is similarly fixed to the camera body or the outer fixed cylinder 14.

The cam cylinder 13 is provided on the outer periphery of the outer fixed cylinder 14 so as to be rotatable in a rotational direction about the optical axis 20. A gear 21 provided on the outer periphery of the cam cylinder 13 drives a zoom motor 22 and the like. When the drive is transmitted from the source, the light source rotates about the optical axis 20.

The movable barrel 16 includes an outer fixed barrel 14 and an inner fixed barrel 1.
5 is movable in the direction of the optical axis 20 and the optical axis 2
The first lens group 10 is provided so as to be rotatable in a rotation direction about 0, and is located closer to the object side inside.

The second lens frame 1 is provided inside the inner fixed barrel 15.
7, a third lens frame 18, two guide rods 24 and 25, and a focus drive mechanism 26 are built-in. The focus drive mechanism 26 is composed of a motor 27 and a lead screw 28 which is the axis of the motor 27, and is attached to the inner fixed cylinder 15 with the axis of the lead screw 28 parallel to the optical axis 20. . Two guide rods 2
Reference numerals 4 and 25 are also fixed in parallel to the optical axis 20 at positions on both sides of the optical axis 20.

The second lens frame 17 holding the second lens group 11 has an engaging portion 2 which engages with the two guide rods 24 and 25.
9 and 30, respectively, and are attached movably along the direction of the optical axis 20. Note that one of the engagement portions 30
Is a rotation stop.

The third lens frame 18 holding the third lens group 12 is provided with a rotation stopper 31 which engages with the guide rod 24.
And a screw portion 32 that engages with the lead screw 28. The optical axis 2 follows the lead of the lead screw 28 rotated by the drive of the focusing motor 27.
It is moved in the direction of 0.

A first lens group 10 is provided on the inner periphery of the cam barrel 13.
For moving the camera along a predetermined magnification trajectory
One first cam groove 33 to 35 is formed. These first cam grooves 33 to 35 pass through three rectilinear guide openings 36 to 38 provided on the outer periphery of the outer fixed cylinder 14 to move the movable cylinder 1.
6, three first cam pins 39 to 4 projecting from the outer periphery
1 is engaged. Thereby, the first cam grooves 33 to 35
Is displaced in the direction of the optical axis 20 in accordance with the amount of rotation of the cam barrel 13 and moves the first lens group 10 in the direction of the optical axis 10 through the first cam pins 39 to 41 by the action of the linear guide openings 36 to 38. Move straight along.

A second cam groove 42 for moving the second lens group 17 along a variable magnification locus different from that of the first lens group 10 is provided on the inner periphery of the cam barrel 13. . The second cam groove 42 protrudes from the outer periphery of the second lens frame 17 through a relief opening 43 provided on the outer periphery of the inner fixed cylinder 15 and a straight guide opening 44 provided on the outer periphery of the outer fixed cylinder 14. The second cam pin 45 is engaged. As a result, the second cam groove 42 is displaced in the direction of the optical axis 20 in accordance with the rotation amount of the cam barrel 13, and the second cam groove 45 moves the second lens frame 17 via the second cam pin 45 by the action of the straight guide opening 44. It is moved straight along the direction of the axis 20. Reference numeral 47 denotes a solid-state imaging device (CCD), which is fixed, for example, to the camera body.

When the camera of the zoom lens device is not used, as shown in FIG. 2, the movable barrel 16 is in the collapsed position where most of the movable barrel 16 has entered the inside of the outer fixed barrel 4, ie, the inside of the camera body. Becomes Reference numeral 48 shown in FIG. 2 is a relief opening provided at the rear end of the movable barrel 16, and the second cam pin 45 enters the opening 48 at the retracted position. Reference numeral 49 denotes an imaging surface of the solid-state imaging device.

When the camera is set in the photographing standby state, the zoom motor 22 is driven, and the cam barrel 13 rotates about the optical axis 20 to move the movable barrel 16 from the retracted position to the position shown in FIG. The zoom of the taking lens is at the telephoto end. When the cam cylinder 13 is further rotated in the same rotation direction by the zoom motor 22, the moving cylinder 16
Is extended to the position shown in FIG. 4, that is, the position most protruding toward the object side, and the magnification of the photographing lens becomes the wide end.

The third lens group 18 is on standby at a predetermined position from the retracted position to the wide end through the telephoto end. On the in-focus locus determined for each position, the lens is moved to a position corresponding to the subject distance at that time.

A first cam pin 39 is provided on the outer periphery of the movable cylinder 16.
In addition to the auxiliary pins 50 to 41, an auxiliary pin 50 is provided to protrude. This auxiliary pin 50 is provided at an angular position different from the first cam pins 39 to 41, as shown in FIG.
The cam cylinder 1 is inserted through a relief opening 51 provided in the outer fixed cylinder 14.
3 protrudes toward the inner peripheral surface. As shown in FIG. 2 to FIG. 4, only the front and rear ends 13a and 13b of the inner periphery of the cam cylinder 13 are in contact with the outer periphery of the outer fixed cylinder 14 as shown in FIGS. A gap 52 is provided between the fixed cylinder 14 and the outer periphery. Auxiliary pin 50
Has a height that protrudes into the gap 52 and does not contact the inner peripheral surface of the cam cylinder 13. In this example, the auxiliary pin 50 is provided on the outer periphery of the movable barrel 16 with the first cam pin 39.
It is provided on the same circumference as to 41.

As shown in FIG. 6, the first cam grooves 33 to 35 are formed at positions where the inner circumference of the cam cylinder 13 is equally divided into three. The first cam grooves 33 to 35 are engaged with first cam pins 39 to 41 indicated by a single circle in FIG. A second cam pin 45 indicated by a double circle is engaged with the second cam groove 42. The movement trajectory of the auxiliary pin 50 is indicated by a thick dashed line.

One of the first cam grooves 33 to 35
The second cam groove 42 intersects the cam groove 35 at the position where the first cam pin 40 is shown in FIG. Here, in this example, the second cam groove 42 is formed deeper than the first cam grooves 33 to 35, and the first cam pins 39 to 41 and the first cam groove 33 are formed.
The engagement allowance between the second cam pin 45 and the second cam groove is larger than the engagement allowance between the second cam pin 45 and the second cam pin 45. Therefore, at this intersection, as shown in FIG. 7, the second cam groove 42 and the second
While the engagement with the guide pin 45 becomes effective, the engagement between the first cam pin 40 and the first cam groove 35 is released because the first cam groove 35 is divided.

As described above, the first cam pins 39 to 41
Are provided at positions obtained by equally dividing the outer periphery of the movable cylinder 16 into three, and the linear guide openings 36 to 38 and the first cam groove 3
The moving cylinder 16 is linearly moved in the direction of the optical axis 20 by being guided to the intersection with 3 to 35. Therefore, the moving cylinder 16 does not smoothly advance and retreat unless an equal force is applied to each of the first cam pins 39 to 41. Therefore, even if the two first cam pins 39 and 41 are engaged with the first cam grooves 34 and 33, the remaining one first cam pin 40 may not be engaged with the first cam groove 35. In this case, the moving cylinder 16 cannot be moved forward and backward smoothly.

Therefore, the auxiliary pin 50 is connected to the movable cylinder 1
6 and engages with the auxiliary pin 50 only when the first cam pin 40 enters the intersection of the first cam groove 35 and the second cam groove 42, and the first cam pin 40 engages with the first cam groove 35. A pair of guide projections 55 and 56 (see FIG. 6) for guiding the auxiliary pin 50 so as to move along the axis are provided to protrude from the inner peripheral surface of the cam cylinder 13 toward the gap 52.

Next, the operation of the above configuration will be briefly described.
When the zoom lens device is in the retracted position, the first cam pins 39 to 41 are out of the first cam grooves 33 to 35 as shown in FIG.
The second cam pin 45 is located at the position indicated by reference numerals A1, A2 and A3 shown in FIG.
, And the auxiliary pin 50 is provided with the reference symbol A5 shown in FIG.
It is located in each position.

When the cam barrel 13 rotates by the angle θ1 shown in FIG.
The moving cylinder 16 is moved toward the object side by an interval between the A position and the B position along the direction of the optical axis 20 while being moved to the positions of B1, B2, and B3 shown in FIG. . At this time, the second cam pin 45 is moved to the position indicated by reference numeral C4 in the second cam groove 42, and the distance between the second lens frame 17 and the position A and C along the direction of the optical axis 20 is set. It is fed to the object side by the minute. As a result, the magnification of the photographing lens becomes the tele end state shown in FIG. At this time, the auxiliary pin 50 indicated by a black circle has moved to the position indicated by the reference symbol B5 in the drawing on the movement locus indicated by the thick dashed line. The rotation direction of the cam barrel 13 from the retracted position toward the telephoto end is upward in FIG. Also,
Regarding the symbols indicating the movement positions of the pins 39 to 41, 45, and 50, the English characters indicate the position in the direction of the optical axis 20, and the numbers indicate the types of the pins.

When the cam barrel 13 further rotates from the telephoto end by an angle θ2 shown in FIG.
Reference numeral 41 denotes a first one of the first cam grooves 33-35,
1, E2 and E3, respectively.
Is fed out to the object side by an interval between the B position and the E position along the direction of the optical axis 20. At this time, the second cam pin 4
5 is moved to the position of F4 in the second cam groove 42 shown in the figure, and the second lens frame 17 is formed on the image forming surface by an interval between the B position and the F position along the direction of the optical axis 20. Evacuate to the side. As a result, the magnification of the photographing lens becomes the wide-end state shown in FIG. At this time, the auxiliary pin 50 has moved to the position indicated by reference numeral E5 in the movement locus indicated by the thick dashed line.

When the cam barrel 13 rotates by the angle θ3 shown in FIG. 3 from the retracted position, the first cam pins 39 to 41 are rotated.
Are the reference numerals A1 and A1 shown in FIG.
The first cam pins 4 moved from the positions A2 and A3 to the positions G1, G2 and G3, respectively, and moved to the position G1.
0 enters the intersection of the first cam groove 42 and the second cam groove 42. At this time, the auxiliary pin 50 moves to the position indicated by the symbol G5 in the movement locus indicated by the thick dashed line,
It enters between the guide projection pairs 55 and 56 and engages with the guide projection pairs 55 and 56. At this time, the second cam pin 45 has moved from the position indicated by reference numeral A4 to the position indicated by H4 in FIG.

The photographic lens at this time is not in the effective zooming area between the telephoto end and the wide end used during shooting, but in the middle of the collapsed area moving from the collapsed position to the effective zooming area. As in this example, if the cam grooves intersect with each other in a section other than the effective zoom range, it is not necessary to consider the focal point movement of the photographing lens and the like. And the second guide grooves 33 to 35 and 42 can be formed substantially linearly, which is inexpensive in terms of cost.

In the above embodiment, the auxiliary pin 50 is
3 does not touch the inner peripheral surface, but in the embodiment shown in FIG. 8, a cam cylinder 70 having an escape groove 60 provided on the inner peripheral surface to release the auxiliary pin 50 along the movement locus of the auxiliary pin 50 is used. I have. Only when the first cam pin 40 enters the intersection of the first cam groove 35 and the second cam groove 42 does the escape groove 60 engage with the auxiliary pin 50, and the first cam pin 40 engages with the first cam groove 35. A pair of guide protrusions 61 and 62 for guiding the auxiliary pin 50 so as to move along the direction are provided so as to protrude in opposite directions, and do not protrude from the inner peripheral surface of the cam cylinder 70.

The escape groove 60 has the same shape as the first cam grooves 33 to 35 because the auxiliary pin 50 is provided in the same movable cylinder 16 as the first cam pins 39 to 41, and is shown in FIG. In this way, as shown in FIG. 8, the first cam pins 40 are formed so as to be shifted in the rotation direction about the optical axis 20 by an amount corresponding to the shift angle between the first cam pins 40. Thus, the auxiliary pin 5
If the escape groove 60 for releasing the zero is provided on the inner peripheral surface of the cam cylinder 13, the pair of guide projections 61 and 62 does not project from the escape groove 60, so the cam cylinder 13 is provided close to the outer periphery of the outer fixed cylinder 14. Therefore, the diameter of the zoom lens barrel can be reduced by the gap 52. 8 and 9, the same functions as those described in FIG. 6 are denoted by the same reference numerals, and detailed description is omitted.

In the embodiment described with reference to FIG. 8, the provision of the clearance groove 60 allows the clearance groove 60 to be provided as shown in FIG.
Intersect with the first cam groove 35 and the second cam groove 42, respectively. However, in this example, the first cam groove 35 and the second cam groove 42 are formed deeper than the escape groove 60,
In addition, since the first cam pin 40 and the second cam pin 45 are made to protrude more than the auxiliary pin 50 to obtain a larger allowance, the first and second cam pins 40 and 45 are intersected at these intersections.
And the first and second cam grooves 35 and 42 are not disengaged from each other, so that the movable barrel 16 and the second lens frame 17 can be smoothly moved without separately providing a guide means. Can be.

In the above embodiment, the depths of the first cam grooves 33 to 35 and the second cam grooves 42 are changed. However, the same depth may be used in the present invention. In this case, it is necessary to provide an auxiliary pin on each lens frame, and to provide first and second guide means for guiding each lens frame when each cam pin passes through the intersection area on the cam barrel. .

Further, in the above embodiment, the bottomed cam groove having the bottom is used. However, the present invention is not limited to this, and the cam groove may be an opening having no bottom. In this case as well, an auxiliary pin is provided for each lens frame, and the first and second guide means are required for the cam barrel, as described above.

As a method of using only one pair of the auxiliary pin and the guide means, there is a method of changing the depth of the cam groove as described above. In addition to this method, the diameter of the cam pin may be changed. . In this case, in the area where the cam grooves having different widths intersect, the small-diameter cam pins are disengaged from the narrow-width cam grooves. Therefore, the auxiliary pins are provided on the lens frame on which the small-diameter cam pins are provided. Just do it. If the diameter of the cam pin is changed in this way, only one pair of the auxiliary pin and the guide means need be provided even when the cam groove has an opening with no bottom.

In the above embodiment, a three-unit zoom lens is constructed in which the power of the lens is in the order of negative, positive and positive. However, the present invention is not limited to this, and at least two lens units are moved in the optical axis direction. There is no need to limit the configuration of the lens group, the power of the lens, and the like, as long as the focal length is changed.

In the above embodiment, the zoom lens device for an electronic still camera is used. However, the present invention is not limited to this, and it goes without saying that the present invention can be applied to a photographic camera, a video camera, and the like.

[0040]

As described in detail above, according to the present invention, since the first cam groove and the second cam groove are provided so as to intersect, the length of the cam cylinder along the optical axis direction is reduced. The length of the lens barrel in the optical axis direction can be reduced, and the thickness of the camera body can be reduced when, for example, a retracted position of the zoom lens is provided. When the cam pins pass through the intersection area, the auxiliary pins guide the lens holding frame, so that the lens holding frame can be moved smoothly. According to the second aspect of the present invention, since the second cam groove is formed to be deeper than the first cam groove, it is only necessary to provide a pair of the auxiliary pin and the guide means, and the cost can be reduced. . According to the third aspect of the present invention, since the intersecting area of the cam groove is provided in the collapsing area, it is not necessary to accurately form the guide means for engaging with the auxiliary pin, and therefore, the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a configuration of a zoom lens device according to the present invention.

FIG. 2 is a cross-sectional view illustrating a retracted position.

FIG. 3 is a cross-sectional view showing a state at a telephoto end.

FIG. 4 is a cross-sectional view showing a state at a wide end.

FIG. 5 is a longitudinal sectional view showing a configuration of a second lens frame, a moving barrel, a cam barrel, and the like.

FIG. 6 is a development view showing an inner peripheral surface of the cam cylinder.

FIG. 7 is an enlarged perspective view showing an intersection between a first cam groove and a second cam groove.

FIG. 8 is a developed view showing an inner peripheral surface of a cam cylinder of another embodiment.

9 is a longitudinal sectional view showing a main part of the zoom lens device according to the embodiment shown in FIG.

[Explanation of symbols]

 Reference Signs List 10 first lens group 11 second lens group 12 third lens group 13 cam barrel 14 outer fixed barrel 15 inner fixed barrel 16 moving barrel 17 second lens frame 18 third lens frame 22, 27 motor 33-35 first cam groove 39 to 41 First cam pin 42 Second cam groove 45 Second cam pin

Claims (3)

[Claims] 1. A lens group constituting a zoom lens is held, and first and second cam pins are respectively protruded from first and second lens holding frames supported movably in an optical axis direction by a linear guide. A zoom lens in which these cam pins are respectively engaged with first and second cam grooves formed in the cam barrel, and the first and second lens holding frames are respectively moved in the optical axis direction by rotation of the cam barrel. In the device, the first cam groove and the second cam groove intersect with each other, and an auxiliary pin protrudes from the first or second lens holding frame at a position different from the first or second cam pin. When the first or second cam pin passes through the intersection area between the first cam groove and the second cam groove, the first or second lens holding frame engages with the auxiliary pin and the first or second lens holding frame moves along the first or second cam groove. Guide to guide you to move along The zoom lens apparatus characterized in that a stage. 2. The first cam groove and the second cam groove are bottomed cam grooves, the second cam groove is formed deeper than the first cam groove, and the second cam pin is formed with the second cam groove. 2. The zoom lens device according to claim 1, wherein the light passes through the intersection while maintaining the engagement of the zoom lens. 3. The first and second cam grooves are provided with first and second cam grooves.
The zoom lens according to claim 1, further comprising a collapsible area for moving the lens holding frame from the effective zoom range to the inside of the camera body, wherein the intersection area is provided in the collapsible area. apparatus.