JP2001108883A - Lens barrel and image pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate the manufacture and to lighten the load on a motor. SOLUTION: A cam follower 12a of a cylinder body 12 which holds a lens part 24 engages a cam groove 14a on the internal surface of a moving cam cylinder 14. The cam groove 14a comprises an insert cam that the cam follower 12a engages when the cylinder body 12 is built in the moving cam cylinder 14, a collapsing cam which holds the cylinder body 12 at a collapsing position, an extension cam which moves the cylinder body 12 between the collapsing position and a photography position for photography, and a photography cam which moves the cylinder body 12 for zooming in the photography position. The collapsing cam and photography cam are so shaped as to closely engage the cam follower 12a and the extension cam is so sectioned as to loosely engage the cam follower 12a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens barrel for moving a lens by a cam and an image pickup apparatus.

[0002]

2. Description of the Related Art As a miniaturized camera, there is known a configuration having a collapsible lens barrel capable of storing a photographing lens in a camera body when photographing is not performed. Such collapsible lens barrels include a so-called zoom lens barrel having a variable focal length composed of a plurality of lens groups. A configuration using a cam mechanism as a means for moving the plurality of lens groups of a zoom lens barrel along a predetermined zoom curve is known. That is,
By driving the cam, the lens group is moved to a predetermined position. In this configuration, the lens barrel can be moved from the storage position to the photographing position by a single cam curve by configuring the cam so that it is in a collapsed state when not photographing.

There is also known a method in which a cam means is used to hold a lens group. For example, a lens group, a plurality of cam followers planted at equal intervals around the lens group, a cylinder that covers these lens groups, and has a cam groove corresponding to the plurality of cam followers, and a rectilinear means for moving the lens group straight. Thus, the lens barrel is not required to hold the lens group, so that the guide bar and the bearing formed in the lens group are not required, and a compact and easy-to-assemble lens barrel can be realized.

Further, a configuration is known in which a lens barrier for protecting the photographic lens is provided on the front surface of the photographic lens when photographing is not performed, and a camera that automatically opens and closes this lens barrier in accordance with the photographic state of the camera is also known. ing. There are known a configuration in which a motor dedicated to opening and closing is provided to open and close the lens barrier, and a configuration in which the lens barrier is opened and closed in conjunction with the retracting operation and the extending operation of the lens barrel.

[0005]

However, in order to obtain the required optical performance as a photographing lens, it is necessary to accurately hold each lens group at a predetermined position. When the lens unit is held by fitting the cam means, the fitting play causes a decrease in the optical performance of the photographing lens. Required. In order to realize the tight fitting setting, it is necessary to reduce the manufacturing error of the cam and the cam follower, which causes an increase in the manufacturing cost of parts.

In the conventional example, the cross-sectional shape of the cam groove is the same between the storage position and the photographable position, and even when the photographing is not performed, the lens group is driven by the cam unit of the same tight fitting setting as in the photographing. Have been. That is, the fitting is tight even though the precision is not required for holding the lens group, a large load is applied to the lens barrel drive, and the motor drive consumes an unnecessary large amount of power. It also caused the cam and cam follower to wear.

In a lens barrel having a lens barrier that automatically opens and closes, the lens barrier is opened and closed in accordance with the retracting operation and the extension operation of the lens barrel. In a lens barrel having such a lens barrier, the load of the collapsing or extending operation of the lens barrel and the load of the opening and closing operation of the lens barrier overlap, and the load on the motor temporarily becomes very large.

[0008] Further, in the case of a device such as a small camera which is often used by being carried around, it is very important to be able to use the device for a long time without replacing or charging the battery. From the viewpoint of extending the driving time, it is required to reduce the load for driving the lens barrel.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a lens barrel and an image pickup apparatus having a low load and a long life.

[0010]

In a lens barrel according to the present invention, a cylindrical body for holding a lens is formed by a cam groove and a cam follower fitted in the cam groove so as to extend in the optical axis direction with respect to the lens barrel base. A lens barrel that is movable, wherein the cam groove has a first size that fits closely to the cam follower in an imaging region, and the cam follower is located on a side of the non-imaging region that is remote from the imaging region. A second size that fits loosely.

[0011] An imaging apparatus according to the present invention includes the above-mentioned lens barrel.

An embodiment of the present invention applied to a camera having a zoom lens barrel in which a lens barrier opens and closes in conjunction with a retracting operation of a lens group will be described in detail with reference to the drawings.

FIG. 1 is a sectional view of an embodiment of the present invention, and FIG.
Shows an exploded perspective view thereof. Lens barrel 10 of the present embodiment
Are six cylinders, namely a cylinder 12, a moving cam cylinder 1
4, a straight-moving barrel 16, a fixed cam barrel 18, a drive ring 20, and a lens barrel base 22. The cylinder 12 closest to the object holds the first lens group 24 located closest to the object. The other lens groups are not shown. A cam follower 12a is provided on the outer periphery of the cylindrical body 12 at intervals of 120 ° in the circumferential direction.
And a columnar rectilinear pin 12b is set up coaxially with the cam follower 12a.

The movable cam cylinder 14 has a cam groove 14a on its inner periphery for feeding the cylinder 12 to a predetermined position. FIG. 3 is a development view of the inner surface of the movable cam barrel 14. Details will be described later,
The movable cam barrel 14 is driven by the drive ring 20 and rotates about the optical axis. With this rotation, the movable cam barrel 14 moves along the cam groove 18a of the fixed cam barrel 18 in the optical axis direction. FIG. 4 is a developed view of the inner surface of the fixed cam barrel 18.

The shape of the cam groove 14a will be described. Cam groove 1
4a is a movable cam cylinder 1 corresponding to the cam follower 12a.
Four pieces are formed in the same shape on the inner circumference of 4 at equal intervals of 120 degrees. By fitting the three cam followers 12a into separate cam grooves 14a, the cylindrical body 12 is three-dimensionally positioned.

The cam groove 14a has four parts, namely,
An insertion cam 14a-1 in which the cam follower 12a is fitted before the cylindrical body 12 is assembled into the movable cam cylinder 14, a retractable cam 14a-2 for holding the cylindrical body 12 in the retracted position, and a photographing in which the cylindrical body 12 is retracted and used for photographing. It comprises a feed cam 14a-3 for moving between positions, and a photographing cam 14a-4 for moving the cylinder 12 zooming within the photographing position.

In order to move the cylinder 12 along the cam groove 14a, the rectilinear cylinder 16 is restricted so as to move straight in the optical axis direction without rotating the cylinder 12. The rectilinear barrel 16 is rotatably fitted to the inner peripheral surface of the movable cam barrel 14. Straight barrel 16
Has an inner diameter larger than the outer diameter of the cylindrical body 12 and an outer diameter smaller than the inner diameter of the movable cam cylinder 14. A retaining pin 16a is implanted on the outermost surface of the rectilinear barrel 16 on the most object side, and is cut in the circumferential direction on the object side of the inner surface of the movable cam barrel 14 so as to face the pin. The retaining groove 14b is formed. When the retaining pin 16a enters the retaining groove 14b, the rectilinear barrel 16 is rotatable around the inner periphery of the movable cam barrel 14 and moves integrally with the movable cam barrel 14 in the optical axis direction.

At the innermost position on the outer periphery of the straight-moving cylinder 16, 12
Three straight keys 16b are erected at equal intervals of 0 degrees. By fitting the straight key 16b into the straight key groove 18b (see FIG. 4) extending in the optical axis direction of the fixed cam barrel 18, the straight barrel 16 can move only in the optical axis direction without rotating.

On the circumference of the straight-moving barrel 16, straight-moving grooves 16c extending in the optical axis direction are formed at three positions corresponding to the straight-moving pins 12b of the tubular body 12. The rectilinear pin 12b of the cylinder 12 fits into the rectilinear groove 16c, whereby the cylinder 12 is restricted only to movement in the optical axis direction. As a result, the moving cam barrel 1
4 rotates, the cylinder 12 does not rotate, and the cam groove 14
It moves in the optical axis direction along a.

The lens barrel base 22 serves as a base for the lens barrel of the present embodiment. The fixed cam barrel 18 is fixed to the lens barrel base 22. 26 (FIG. 1) is an imaging surface.

On the outer peripheral surface of the movable cam barrel 14, three cam followers 14c are erected at equal intervals of 120 degrees on the circumference around the optical axis. Three cam grooves 18a are formed on the inner periphery of the fixed cam barrel 18 at equal intervals of 120 degrees in the same shape, corresponding to the cam followers 14c. The moving cam barrel 14 is positioned by fitting the three cam followers 14c into different cam grooves 18a.

The fixed cylinder 18 enters the drive ring 20 almost closely. The drive ring 20 rotationally drives the movable cam barrel 14 with the above-described configuration. On the inner peripheral surface of the drive ring 20, 12
Drive key grooves 20a extending in the optical axis direction at equal intervals of 0 degrees are formed. Three drive pins 1 are provided on the outer peripheral surface of the movable cam barrel 14 so as to be individually fitted into the drive key grooves 20a.
4d are planted. Drive keyway 20a and drive pin 1
By the fitting of 4d, the movable cam barrel 14 rotates with the rotation of the drive ring 20. The driving pin 14d is fixed cam cylinder 1
8 penetrates.

Referring to FIG. 4, the structure of the inner surface of the fixed cam barrel 18 will be described in detail. The cam groove 18a includes four main parts, namely, an insertion cam 18a-1 for incorporating the movable cam barrel 14 into the fixed cam barrel 18, a collapsible cam 18a-2 for holding the movable cam barrel 14 at the collapsed position, Cam cylinder 14
And a photographing cam 18a-4 for moving the movable cam barrel 14 by a zoom operation within the photographing position. As described above, since the cam follower 14c is fitted in the cam groove 18a and the movable cam barrel 14 is rotated by the drive ring 20, the movable cam barrel 14 moves in the optical axis direction according to the cam groove 18a. Reference numeral 18c denotes an escape hole for the drive pin 14d to pass through the fixed cam barrel 18.

The overall operation of the lens barrel 10 of the embodiment will be described. Assuming that the lens barrel 10 is in the collapsed state as an initial state, an operation of extending the lens barrel 10 from the collapsed state to the photographing state will be described. The drive ring 20 is driven to rotate by a motor (not shown).

In the collapsed state, the cam follower 12a is fitted into the collapsed cam 14a-2 of the cam groove 14a of the movable cam barrel 14. The cam follower 14c is fitted in the collapsible cam 18a-2 of the cam groove 18a of the fixed cam barrel 18. FIG.
D indicates the rotation direction of the drive ring 20. The direction of the arrow is forward rotation. When the drive ring 20 rotates forward in this state, the lens barrel 10 is extended and becomes ready for photographing.

The rotation of the drive ring 20 is performed by first moving the movable cam barrel 14.
Conveyed to. When the movable cam barrel 14 rotates, the cam follower 14c moves from the retracted cam 18a-2 of the fixed cam barrel 18 to the feeding cam 18a-3. At this time, the cylinder 1
2 is not rotated by the rectilinear barrel 16, the cam follower 12 a is moved by the rotation of the movable cam barrel 14.
The cam groove 14a moves from the collapsed cam 14a-2 to the feeding cam 14a-3.

As described above, the movable cam barrel 14 is extended by the rotation of the drive ring 20, and the extended movable cam barrel 14 is extended.
, The cylindrical body 12 is extended. When the drive ring 20 further rotates, the barrel 12 and the movable cam barrel 14 move onto the photographing cams 14a-4 and 18a-4, respectively, and the lens barrel 10 becomes ready for photographing. The absolute position of the cylinder 12 is the cylinder 12
And the position of the moving cam barrel 14 are added.

FIG. 5 shows cam curves of the cam grooves 14a and 18a and a cam curve obtained by adding them. The horizontal axis indicates the rotation angle of the drive ring 20 when the retracted position is set to 0 degree. The vertical axis indicates the displacement from the retracted position. 30 is the cam groove 14a
And 32 indicates a cam curve of the cam groove 18a. Reference numeral 34 denotes a cam curve obtained by adding the cam curve 30 and the cam curve 32. The composite cam curve 34 indicates the displacement of the cylinder 12 from the imaging surface 26.

The lens barrier mechanism 40 of the lens barrel 10 will be described. FIG. 6 is an exploded perspective view of the lens barrier mechanism 40 in an open state. The lens barrier mechanism 40 is
It consists of a plate-like barrier 42, 44, 46, 48. The barriers 42 and 44 have the same shape as each other, and mainly shield the central portion of the front surface of the lens. The barriers 46 and 48 have the same shape as each other, and mainly shield the periphery of the front surface of the lens from light. These barriers 42, 44, 46, and 48 open and close the front surface of the lens by a rotating operation as described later. Barriers 42 and 44
The shapes and operations of the barriers 46 and 48 are point-symmetric with respect to the optical axis, and the shapes and operations of the barriers 46 and 48 are point-symmetric with respect to the optical axis.

At one end of the barriers 42 and 44, the barriers 42 and
Holes 42a and 44a serving as a center of rotation of 44 are opened,
A shaft (not shown) of the cylindrical body 12 is fitted into each of the holes 42a and 44a. Similarly, holes 46a, 48a serving as rotation centers of the barriers 46, 48 are formed at one ends of the barriers 46, 48, and the holes 46a, 48a are respectively provided with holes 42a, 48a.
The same shaft of the cylindrical body 12 that fits into the a and 44a is fitted. The barriers 46, 48 rotate about the barriers 46a, 48a in conjunction with the barriers 42, 44, respectively.

Reference numeral 50 denotes a barrier driving plate for driving the barriers 42 and 44 to rotate. The barrier drive plate 50 is fitted to the cylinder 12 and is rotatable about the optical axis. Barrier drive plate 5
The cutouts 50a and 50b are formed on both sides 180 ° apart from 0. The notch 50a has a hole 4 in the barrier 42.
Barrier drive pin 42b planted near 2a intervenes,
A barrier drive pin 44b erected near the hole 44a of the barrier 44 intervenes in the notch 50b. When the barrier drive plate 50 rotates about the optical axis, the notches 50a, 5
The barriers 42 and 44 rotate about the holes 42a and 44a by the engagement of the barrier drive pins 42b and 44b with 0b.

The barrier driving plate 50 is urged in the direction B (FIG. 2) by a spring (not shown). Thereby, the barriers 42 and 44 are urged in the opening direction, and the barriers 46 and 48 are opened.
Is urged in the opening direction in conjunction with the barriers 42 and 44. When the lens barrel is in a photographable state, the barrier driving plate 50 can rotate freely, and the barriers 42, 44, 46, 4
Numeral 8 is always opened by a spring for urging the barrier drive plate 50 in the B direction.

A barrier projection 50c is formed on the imaging surface side of the barrier drive plate 50, and a fixed projection 52 is formed on the lens barrel base 22 corresponding to the barrier projection 50c.
The slope 50d of the barrier projection 50c and the slope 52a of the fixed projection 52 face each other. Slope 50d of barrier projection 50
And the slope 52a of the fixed projection 52 do not contact when the lens barrel 10 is in the photographing state, but the cam follower 12a
Are fitted to the feeding cam 14a-3 and come into contact with the cam during the transition to the collapsed state. As the cylinder 12 further moves in the collapsed direction, the slope 50d of the barrier projection 50 receives a force while sliding on the slope 52a of the fixed projection 52, and the barrier drive plate 50 is moved in the direction opposite to the direction B in FIG. Rotate. As a result, the barriers 42 to 48 gradually close against the force of the spring. Before the cam follower 12a of the cylinder 12 completely moves to the collapsed cam 14a-2, the barriers 42 to 48 are completely closed.

FIG. 7 shows the collapsed cam 14a- of the cam groove 14a.
2 and a sectional view of the photographing cam 14a-4. The cam follower 12a includes a collapsible cam 14a-2 and a photographing cam 1
4a-4 Fits tightly. In many cases, the camera is carried in a collapsed state, and the lens barrel 10 needs to have a strength capable of withstanding vibration and impact when carried. If the backlash of the cam in the collapsed state is large, the lens barrel 10 may move violently due to vibration or impact, and the cam may be damaged. Therefore, the collapsed cam 14a-2 is replaced with the photographing cam 14a-4.
Although not as good, they must be tightly fitted. In the shooting state, it is necessary to accurately position the cylinder 12 in order to exhibit required optical performance.
Tight fitting and high precision are required for cams.

On the other hand, when the lens barrel is extended, it is not necessary to hold the cylinder 12 and it is not necessary to accurately position the cylinder.
Therefore, it is possible to loosen the fitting of the cam, and it is preferable to loosen the cam. FIG. 8 shows an example of a sectional view of a part of the feed cam 14a-3 of the cam groove 14a. In this example, the cross section of the cam follower 12a is
By loosening the groove a-3, loose fitting with the cam follower 12a is realized. By loosening the fitting in this way, the load on the motor that drives the lens barrel is reduced, power consumption can be suppressed, and wear of the cam follower and the cam groove can be reduced. Furthermore, in the dispensing cam 14a-3 which is loosely fitted, the cam groove does not need to have high precision, so that the manufacturing cost of the movable cam cylinder 14 can be reduced.

FIG. 9 shows the cam 14 extending from the cam groove 14a.
4 shows another cross-sectional structure of part of a-3. In this example, loose fitting with the cam follower 12a is realized by increasing the width of the groove of the cam 14a-3 with respect to the cross-sectional shape of the cam follower 12a. As a result, the above-described power saving effect, component wear reduction effect, and cost reduction effect are realized.

The relationship between the cam fitting state of the cylinder 12 and the movable cam cylinder 14 and the operation state of the lens barrier will be described. Cylinder 1
When the second cam follower 12a is fitted to the photographing cam 14a-4, as shown in FIG.
0c and the fixing projection 52 are largely separated. With collapsing,
The cam follower 12a of the cylindrical body 12 extends the cam 14a-
3, but shortly before the cylindrical body 12 reaches the point P in FIG. 3, the barrier projection 50c and the fixing projection 52 are separated from each other as shown in FIG. Immediately before the point P, the barrier projection 50c and the fixed projection 52 start to abut as shown in FIG. Thereafter, as the lens is retracted, the barrier driving plate 50 is rotated while the slope 50d of the barrier projection 50c and the slope 52a of the fixed projection 52 rub as shown in FIG.
The lens barrier mechanism 40 closes. FIG. 13 shows a contact state between the barrier projection 50c and the fixed projection 52 when completely retracted.

When the cam follower 12a is fitted with the photographing cam 14a-4, the cylindrical body 12 does not rattle as described above. When the barrier projection 50c and the fixed projection 52 are in contact with each other, an urging force acts on the cylindrical body 12 in the optical axis direction,
The rattling is suppressed. Therefore, since the fitting of the cylindrical body 12 changes to a loose state after the barrier projection 50c and the fixed projection 52 come into contact with each other, the cylindrical body 12 never rattles regardless of which cam is fitted.

The feeding cam 1 having the cross section shown in FIG. 8 or FIG.
4a-3 and the cams 14a-2 and 14a having the cross section shown in FIG.
As shown in FIG. 3, -4 is connected with a gently changing shape. Thereby, the cam follower 12a can smoothly transition between tight fitting and loose fitting without being caught halfway.

By contact between the slope 50d of the barrier projection 50c and the slope 52a of the fixed projection 52, the cylinder 12 is urged in a direction to push it toward the subject. By designing the slope 50d of the barrier projection 50c and the slope 52a of the fixed projection 52 to be in contact with each other immediately before the gentle change of the shape of the feeding cam 14a-3, the lens barrel can be fitted even if the fitting of the cam becomes loose. Does not rattle.

As described above, the lens barrier mechanism 40
Is closed when the lens barrel is collapsed, but at this time, a large load is applied to the motor because it resists the urging force of the spring. But,
As in the present embodiment, by loosening the fitting of the cam with the extension cam 14a-3 of the lens barrel, the load for driving the lens barrel can be dispersed. As a result, the peak of the load applied to the motor can be significantly reduced, and the driving voltage of the motor can be reduced. Since the minimum drive voltage of the camera body can be set low by lowering the drive voltage of the motor, the drive time of the camera can be extended.

When the strength of the cam is not broken even if the lens barrel moves violently due to vibration or impact, the retractable cam 14a-2 can be a loosely fitted cam. This can further reduce wear and manufacturing costs.

[0043]

As can be easily understood from the above description, according to the present invention, by partially loosening the fitting of the cam, the power consumption of the camera is reduced, and the abrasion of the cam and the manufacturing cost are reduced. it can.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of one embodiment of the present invention.

FIG. 2 is an exploded perspective view of the present embodiment.

FIG. 3 is a view in which the movable cam barrel 14 is developed in a plane and viewed from the inside.

FIG. 4 is a view showing the fixed cam barrel 18 developed in a plane and viewed from the inside.

FIG. 5 is a diagram showing cam curves of a cam groove 14a and a cam groove 18a and their combined cam curves.

FIG. 6 is an exploded perspective view of the lens barrier mechanism 40 with the barrier open.

FIG. 7 is a sectional view of a retractable cam 14a-2 and a photographing cam 14a-4 in a cam groove 14a.

FIG. 8 is a sectional view of an extension cam 14a-3 of the cam groove 14a.

FIG. 9 is a cross-sectional view of another configuration of the extension cam 14a-3 of the cam groove 14a.

FIG. 10 shows a cam follower 12a having a photographing cam 14a-4.
The barrier projection 50 and the fixed projection 52 when fitted in
It is a figure which shows the positional relationship of.

11 is a diagram showing a positional relationship between a barrier protrusion 50 and a fixed protrusion 52 when the cam follower 12a reaches a point P in FIG.

FIG. 12 is a diagram showing a positional relationship between a barrier projection 50 and a fixed projection 52 when retracted further than in FIG. 11;

FIG. 13 is a diagram showing a positional relationship between a barrier projection 50 and a fixed projection 52 when completely retracted.

[Explanation of symbols]

 10: Lens barrel 12: Cylindrical body 12a: Cam follower 12b: Straight pin 14: Moving cam cylinder 14a: Cam groove 14a-1: Insert cam 14a-2: Collapse cam 14a-3: Feeding cam 14a-4: Shooting cam 14b : Retaining groove 14c: Cam follower 14d: Drive pin 16: Straight advance cylinder 16a: Retention pin 16b: Straight advance key 16c: Straight advance groove 18: Fixed cam cylinder 18a: Cam groove 18a-1: Insertion cam 18a-2: Retract cam 18a -3: feeding cam 18a-4: photographing cam 18b: straight keyway 18c: relief hole 20: drive ring 20a: drive keyway 22: lens barrel base 24: first lens group 26: imaging surface 30: cam groove 14a Cam curve 32: Cam curve of cam groove 18a 34: Composite cam curve 40: Lens barrier mechanism 42, 44, 46, 48: Barrier 4 a, 44a, 46a, 48a: hole 42b, 44b: barrier drive pin 50: barrier driver plate 50a, 50b: notch 50c: barrier projection 50d: slope 52 of the barrier projection 50c: fixing protrusion 52a: inclined surface of the fixing protrusion 52

Claims (5)

[Claims] 1. A lens barrel in which a cylindrical body for holding a lens is movable back and forth in the optical axis direction with respect to a lens barrel base by a cam groove and a cam follower fitted in the cam groove. The groove has a first size that fits closely with the cam follower in the photographing area, and has a second size that loosely fits in the cam follower on the side of the non-photographing area remote from the photographing area. A lens barrel characterized by the following. And a lens barrier mechanism that opens and closes in accordance with the position of the cylindrical body.
2. The lens barrel according to claim 1, wherein when shifting from the imaging state to the non-imaging state, the closing operation is started when the cam follower is fitted in the first size cam groove. 3. And a lens barrier mechanism that opens and closes in accordance with the position of the cylindrical body.
When shifting from the imaging state to the non-imaging state, the closing operation is started when the cam follower is fitted into the first size cam groove, and the cam follower is moved to the second size cam groove. The lens barrel according to claim 1, wherein the closing operation is completed when the lens barrel is fitted to the lens barrel. 4. A lens barrier mechanism that opens and closes according to the position of the cylindrical body, wherein the lens barrier mechanism comprises:
2. The lens barrel according to claim 1, wherein the lens barrel closes when the cam follower is fitted in the second size cam groove when the imaging state is shifted to the non-imaging state. 3. 5. An imaging apparatus comprising the lens barrel according to claim 1. Description: