JP2005148367A - Lens barrel and camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a smooth motion without increasing the cost caused by change in the materials and addition of other materials for a lens barrel having a small radius or a large amount of extension requiring to form a cam groove that approaches to an optical axis in a parallel manner and simply exceeds an angular limit for the lens barrel which incorporates a plurality of lenses and is freely retracted and extended and a camera having the lens barrel. <P>SOLUTION: The lens barrel is provided with a first holding member which holds a first lens group, a second holding member which holds a second lens group and a cam groove 162 which relatively rotates at least one of the first holding member or the second holding member with respect to the other around the optical axis. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a lens barrel that includes a plurality of lens groups and that can be retracted and extended, and to a camera that includes such a lens barrel.

  Conventionally, the above lens barrel and camera are known.

  For example, Patent Document 1 aims to increase the amount of movement of the lens group and prevent the cam ring from being exposed to the outside when the lens barrel is extended forward. A cam ring that is supported in this manner, a moving lens group frame that supports rotation on the inner peripheral side of the cam ring and that can only move in the optical axis direction, and a lens group that is formed on the inner peripheral surface of the cam ring. And a lens group cam mechanism for moving the moving lens group frame by a movement amount larger than the cam ring by rotation of the cam ring, and a cam ring for the cam ring, and positioned so as to cover the cam ring on the outer peripheral side of the cam ring. There has been proposed a lens barrel having an outer lens barrel ring engaged with the cam ring so as to freely rotate relative to the cam ring and move together in the optical axis direction.

Further, Patent Document 2 aims to reduce the size in the direction of the optical axis and rotates around the optical axis and has a first and second cam grooves formed on the outer surface and the inner surface, respectively, and the optical axis direction. There has been proposed a lens barrel having an intermediate unit tp composed of first and second rectilinear cylinders which go straight and are arranged on the outer side and the inner side of the rotary cylinder, respectively.
JP 2002-277709 A JP 2003-66308 A

  In recent years, there has been a demand for a photographic lens with an increasingly high zoom magnification as a photographic lens aimed at expanding the photographic area, and the amount of lens extension for adjusting the focal length tends to increase.

  On the other hand, in recent years, digital cameras that provide an image sensor on the imaging surface of a photographing lens and generate image data are rapidly spreading, and the image sensor is generally smaller in area than a photographic film for one frame, and therefore The lens diameter of photographing lenses tends to be reduced.

  Therefore, there is a demand for a lens barrel that is a small-diameter tube and moves greatly in the optical axis direction.

  Here, in order to move in the optical axis direction, the lens barrel moves in the optical axis direction relative to the cylinder in which cam grooves that are oblique to the optical axis are formed on the inner peripheral surface and the outer peripheral surface. A cam pin that fits into the cam groove is provided on the cylinder, and the two cylinders are relatively rotated to extend in the direction of the optical axis. In this case, the cam groove is too long from the direction perpendicular to the optical axis. However, if it moves off and approaches parallel to the optical axis, rotation around the optical axis cannot be converted into movement in the optical axis direction. The angle in the direction in which the cam groove extends depends on the material of the cylinder and the cam pin, but must be suppressed to 55 degrees or less with respect to the direction perpendicular to the optical axis.

  However, as described above, in the case of a lens barrel having a small diameter and a large amount of movement in the optical axis direction, the cam groove having a short distance around the optical axis and a long distance in the optical axis direction, that is, exceeding the angle limit described above. The cam groove becomes parallel to the optical axis at an angle, and with this state, the smooth movement of the lens barrel cannot be ensured. In order to solve this problem, it is conceivable that the angle limit will be exceeded by devising the material or adding another member to lower the sliding resistance between the cam groove and the cam pin. Since the material is selected in consideration of the strength and the like, there is a problem that it is inevitable to increase the cost by changing to a different material or adding a member.

  In view of the above circumstances, the present invention simply changes the material even in a lens barrel having a small diameter or a large feeding amount to the extent that it is necessary to form a cam groove that exceeds the angle limit and is parallel to the optical axis. It is another object of the present invention to provide a lens barrel and a camera including the lens barrel that can be smoothly moved without increasing costs due to the addition of another member.

The lens barrel of the present invention that achieves the above object includes a plurality of lens groups each including a first lens group that is the foremost in the optical axis direction and that moves in the optical axis direction, and a second lens group that is adjacent to the first lens group. In the built-in lens barrel that can be retracted and extended freely,
A first holding member that holds the first lens group;
A second holding member for holding the second lens group;
A cam mechanism for rotating at least one of the first holding member and the second holding member relative to the other around the optical axis while moving the first holding member and the second holding member in the optical axis direction; It is characterized by that.

Here, in the lens barrel of the present invention, the cam mechanism is
A first cam groove for driving the first holding member is formed on one of the outer peripheral surface and the inner peripheral surface, and driving for driving the second holding member on the other of the outer peripheral surface and the inner peripheral surface is required. A cam cylinder having a second cam groove having a rotation amount different from that of the first cam groove;
At least one of the first holding member and the second holding member is relative to the other relative to the other around the optical axis by a compensation amount that compensates for the difference in rotation amount required for driving between the first cam groove and the second cam groove. And a lens rotation mechanism that rotates the lens.

In this case, the lens rotation mechanism is
A first key for restricting rotation of the first holding member;
A second key for restricting rotation of the second holding member;
A first key groove that guides the first key and the second key in the direction of the optical axis and rotates at least one of the first key and the second key relative to the other around the optical axis by a compensation amount. And a fixing member in which a second keyway is formed.

  The lens barrel can be retracted and extended, and the focal length can be adjusted in the extended state, wherein the cam mechanism includes a first holding member and a second holding member. In adjusting the focal length in the extended state, at least one of the first and second holding members is rotated only between the retracted and extended relative to the other around the optical axis. It is also preferable that the rotation is prohibited and straightened.

  It is also a preferable aspect that a light amount control member for controlling the light amount of the subject light passing through the lens barrel is provided, and the second holding member holds the second lens group and holds the light amount control member. is there.

In addition, the camera of the present invention that achieves the above object includes a plurality of lens groups each including a first lens group forward in the optical axis direction that moves in the optical axis direction and a second lens group adjacent to the first lens group. In a camera that has a built-in lens barrel that can be retracted and extended, and captures subject light that has passed through the lens barrel.
The lens barrel
A first holding member that holds the first lens group;
A second holding member for holding the second lens group;
A cam mechanism for rotating at least one of the first holding member and the second holding member relative to the other around the optical axis while moving the first holding member and the second holding member in the optical axis direction; It is characterized by that.

  The members corresponding to the first holding member and the second holding member in the present invention are normally configured to move in a straight line in the optical axis direction while prohibiting rotation around the optical axis. On the other hand, in the case of the lens barrel of the present invention, one of the first holding member and the second holding member is moved with respect to the other while moving the first holding member and the second holding member in the optical axis direction. Since the cam mechanism that rotates around is provided, the angle at which the cam groove extends by the amount of rotation of the relative rotation can be set away from the direction parallel to the optical axis, reducing the diameter and lengthening the feed amount. Fits.

  Embodiments of the present invention will be described below.

  1 and 2 are external perspective views of a digital camera which is an embodiment of the camera of the present invention in which an embodiment of the lens barrel of the present invention is incorporated.

  Here, FIG. 1 shows an appearance when the lens barrel incorporated in the digital camera is in the retracted state, and FIG. 2 shows an appearance when the lens barrel is in the extended state. It is shown.

  The lens barrel 100 of the digital camera 1 shown in FIGS. 1 and 2 incorporates a photographic lens composed of three groups as will be described later, and the first group and the second group among the three groups of lens groups. The focal length is adjusted by moving the group in the optical axis direction, and the focus is adjusted by moving the focus lens of the third group in the optical axis direction.

  An auxiliary light emission window 12 and a viewfinder objective window 13 are arranged at the upper front of the digital camera 1 shown in FIGS. A shutter button 14 is disposed on the upper surface of the digital camera 1.

  A zoom operation switch is provided on the rear surface (not shown) of the digital camera 1. When one of the zoom operation switches is pressed, the lens barrel 100 is extended to the telephoto side while the button is being pressed, and the zoom operation switch is When the other is pressed, the lens barrel 100 moves to the wide-angle side while continuing to press.

  3, 4 and 5 are cross-sectional views along the optical axis of the lens barrel incorporated in the digital camera shown in FIGS. 3, 4 and 5 show a maximum wide angle state (referred to as a wide end), a maximum telephoto state (referred to as a tele end) and a retracted state, respectively. 3, 4, and 5 are not accurate cross-sectional views but originally exist on the cross-sectional view so that elements necessary for explaining the operation of the lens barrel appear on the cross-sectional view. Elements not present at other angular positions around the optical axis are also shown on this cross-sectional view.

  The lens barrel 100 includes a three-group photographic lens including a first lens group 210, a second lens group 220, and a third lens group 230. The third lens group 230 of the three-group photographic lenses is used as a focus lens.

  Here, the first lens group 210 is held by the first moving cylinder 110. In addition, a decorative plate 119 that covers the periphery of the front surface of the first lens group 210 is also attached to the first moving cylinder 110.

  The first moving cylinder 110 is provided with a cam follower pin 111, and this cam follower pin 111 is engaged with a cam groove 121 (see FIG. 6A) on the outer peripheral surface of the cam cylinder 120.

  Further, the first moving cylinder 110 is provided with a rotation restricting portion 112 for receiving the restriction of the rotation around the optical axis, and this rotation restricting portion 112 is provided in the intermediate tube 130 surrounding the cam tube 120. The key groove 131 is fitted. Therefore, the first moving cylinder 110 and the intermediate cylinder 130 can be relatively moved in the optical axis direction, and the rotation around the optical axis is performed only integrally.

  Further, the protruding ridge 122 provided in the cam cylinder 120 and making a round in the rotational direction is fitted in a groove 132 provided in the intermediate cylinder 130 and making a round in the rotational direction. Therefore, the cam cylinder 120 and the intermediate cylinder 130 are inserted. Can rotate relative to the optical axis, and can move only integrally in the optical axis direction.

  Therefore, when the intermediate cylinder 130 and the cam cylinder 120 rotate relatively, the first moving cylinder 110 moves in the optical axis direction according to the shape of the cam groove 121 provided on the outer peripheral surface of the cam cylinder 120, and the first movement The first lens group 210 held by the cylinder 110 moves in the optical axis direction.

  The second lens group 220 constituting this photographing lens is held by the second lens frame 140. In addition, the second lens frame 140 further holds a holding member 145 that holds a shutter unit 147 including a shutter and an aperture so as to be slidable in the optical axis direction within a predetermined range with respect to the second lens frame 140. ing. The holding member 145 is biased forward in the optical axis direction by a coil spring 146, and the holding member 145 is photographed farthest from the second lens frame 140 in the extended state shown in FIGS. In the retracted state shown in FIG. 5, the lens is pushed by the first lens frame 110 and placed in the storage position close to the second lens frame 140.

  The second lens frame 140 has a cam follower pin 141 on its outer peripheral surface, and the cam follower pin 141 is engaged with a cam groove 123 (see FIG. 6B) provided on the inner peripheral surface of the cam cylinder 120. . On the outer peripheral surface of the second lens frame 140, three cam follower pins 141 are provided in the circumferential direction, two in the front and rear (total of six), and the two cam follower pins in the front and rear are as follows. They are provided at positions shifted from each other in the rotational direction. That is, although FIG. 6 will be mentioned later, when the front cam follower pin is engaged with the point A of the cam groove 123 shown in FIG. 6B, the rear cam follower pin is engaged with the point B. Thus, they are provided at different positions in the rotation direction.

  As shown in FIGS. 3 to 5, the second lens frame 140 has a key groove 142 that fits into the straight key ring 150. Therefore, the second lens frame 140 is prohibited from rotating around the optical axis with respect to the straight key ring 150 and can only move in the optical axis direction.

  Further, the linear key ring 150 is provided with a protrusion 151 that makes a round in the circumferential direction, and the protrusion 151 fits into a groove 124 that is provided in the cam cylinder 120 and makes a round in the circumferential direction. ing. Therefore, the linear key ring 150 and the cam cylinder 120 can only be rotated around the optical axis, and the movement in the optical axis direction is performed integrally.

  Therefore, when the cam cylinder 120 rotates relative to the rectilinear key ring 150 around the optical axis, the second lens frame 140 moves in the optical axis direction according to the cam groove 123 provided on the inner peripheral surface of the cam cylinder 120.

  Further, the rectilinear key ring 150 is fitted in a rectilinear groove 161 provided in the fixed cylinder 160. Therefore, the rectilinear key ring 150 is prohibited from rotating around the optical axis and only moved in the optical axis direction.

  Further, the intermediate cylinder 130 has a cam follower pin 133 that fits into a cam groove 162 provided in the fixed cylinder 160. The cam groove 162 extends so as to rotate by 15 ° while being extended from the retracted state shown in FIG. 5 to the wide end shown in FIG. 3 (see FIG. 7). Therefore, the intermediate cylinder 130 and the first moving cylinder 110 are fed out in the optical axis direction while rotating 15 ° between the retracted state (FIG. 5) and the wide end (FIG. 3) according to the cam groove 162.

  In addition, cam follower pins 125 are planted at three locations on the outer periphery of the cam cylinder 120, and the cam follower pins 125 are provided in the fixed cylinder 160 and are provided through the front and back of the fixed cylinder 160. The groove 163 passes through and is fitted into a key groove 171 provided on the inner surface of the drive cylinder 170.

  The drive cylinder 170 receives a driving force from a zoom motor (not shown) and is driven to rotate around the optical axis. The rotation is transmitted to the cam cylinder 120 via the cam follower pin 125, and the first lens group 210 and the second lens group 220 are driven. Is changed according to the cam grooves 121 and 123 on both the outer peripheral surface and the inner peripheral surface of the cam cylinder 120, and zooming is performed.

  The focus lens that is the third lens group 230 is held by the holding frame 180. The holding frame 180 includes a guide portion 181 having a guide hole 181a through which the guide bar 191 passes, and a nut 182 that is screwed into the feed screw 192 is fixed to the holding frame 180.

  A rotational driving force of the focus motor 190 is transmitted to the feed screw 192 via a gear train (not shown), the feed screw 192 rotates, and the holding frame 180 responds to the rotation of the feed screw 192 with the rotation. The lead screw 192 and the guide frame 191 are guided by that amount and moved in the optical axis direction for focus adjustment. Thus, the subject light that has passed through the first lens group 210, the second lens group 220, and the third lens group (focus lens) passes through the optical filter 310 and is coupled to the light receiving surface 320a of the CCD solid-state imaging device 320. Image. In the CCD solid-state imaging device 320, an image signal representing a subject image formed on the light receiving surface 320a is generated.

  FIG. 6 is a view showing the shape of the cam groove provided in the cam cylinder 120. 6A and 6B show the shapes of the cam groove 121 provided on the outer peripheral surface and the cam groove 123 provided on the inner peripheral surface of the cam cylinder 120, respectively.

  A cam follower pin 111 of the first moving cylinder 110 shown in FIGS. 3 to 5 is fitted in the cam groove 121 on the outer peripheral surface of the cam cylinder 120 shown in FIG. 6A. The cam follower pin 111 is inserted into the lens barrel when the lens barrel is in the retracted state, and the illustrated position of 75 ° is the position where the cam follower pin 111 is inserted when the lens barrel is at the wide end. The position of ° is the insertion position of the cam follower pin 111 when the lens barrel is at the telephoto end.

  In addition, a cam follower pin 141 provided on the outer periphery of the second lens frame 140 is fitted into the cam groove 123 provided on the inner peripheral surface of the cam cylinder 120 shown in FIG.

  The points A and B indicated by the alternate long and short dash line in FIG. 6B are the insertion positions of the cam follower pins 141 when the lens barrel is in the retracted state, and the positions rotated by 60 ° from the points A and B are as follows. The insertion position of the cam follower pin 141 when the lens barrel is at the wide end, and the position rotated 145 ° from the points A and B is the insertion position of the cam follower pin 141 when the lens barrel is at the tele end.

  As described above, the cam follower pins 141 provided on the outer periphery of the second moving cylinder 140 are provided at three positions in the circumferential direction and two at the front and rear at positions shifted in phase from each other. Here, in the state rotated 60 ° from the points A and B (collapsed state) (wide end), the rear cam follower pin of the two cam follower pins provided at the front and rear (in the retracted state, the point B is inserted into the point B). The cam follower pin) is disengaged from the cam groove 123, but the front cam follower pin (the cam follower pin fitted in the point A in the retracted state) is fitted in the cam groove 123. Similarly, in the state rotated by 145 ° from the points A and B (collapsed state) (tele end), the front cam follower pin (point A in the collapsed state is point A in the retracted state). The cam follower pin inserted into the cam groove 123 is disengaged from the cam groove 123, but this time the rear cam follower pin (inserted at point B in the retracted state). Since Muforowapin) is a state of being fitted in the cam groove 123, the position of the second movable barrel 140 is determined with respect to the cam groove 123 in this state.

  Thus, by providing two front and rear cam follower pins whose phases are shifted from each other on the outer periphery of the second moving cylinder 140, at least one of the front and rear cam follower pins 141 is always fitted and positioned in the cam groove 123. Is preserved.

  Here, as shown in FIG. 6, the cam groove 121 provided on the outer peripheral surface of the cam cylinder 120 is a cam groove that extends the first movable cylinder 110 to the wide end by rotating 75 ° from the retracted state. The cam groove 123 provided on the inner peripheral surface of the cam cylinder 120 is a cam groove that extends the second movable cylinder 140 to the wide end by rotating 60 ° from the retracted state. That is, these cam grooves 121 and 123 have different rotational amounts for driving the first moving cylinder 110 and the second moving cylinder 140 from the retracted state to the wide end, respectively. When extending to the wide end, there is a contradiction that one cam cylinder 120 needs to be rotated by 75 ° on the outer peripheral surface and rotated by 60 ° on the inner peripheral surface. The means for solving this contradiction will be described later. Here, first, the reason why the rotation amount necessary for feeding from the retracted state to the wide end is different between the outer peripheral surface and the inner peripheral surface of the cam cylinder 120 will be described.

  The cam grooves 121 and 123 have a function of converting the driving force in the rotational direction of the cam cylinder 120 into a driving force in the optical axis direction, and the angle θ shown in FIG. Is preferable. As this angle θ increases, the frictional resistance between the cam follower pin and the cam groove increases and the conversion efficiency decreases, and further, the material of the cam cylinder 120 and the material of the cam follower pin fitted into the cam groove of the cam cylinder are reduced. However, if the angle θ exceeds a predetermined limit angle determined by the material or the like, the driving force in the rotational direction cannot be converted to the driving force in the optical axis direction.

  In the present embodiment, the illustrated angle θ of the cam groove 121 provided on the outer peripheral surface of the cam cylinder 120 shown in FIG. 6A is about 52 °, and the driving force of the zoom motor (not shown), Considering the material of the cam cylinder and cam follower pin, etc., it is close to the limit angle, and as with the cam groove 123 on the inner peripheral surface shown in FIG. Providing the groove 121 results in the angle θ exceeding the limit. Accordingly, the cam groove 121 on the outer peripheral surface of the cam cylinder 120 is provided so as to extend the first moving cylinder 110 to the wide end by rotating 75 ° from the retracted state.

  On the other hand, the cam groove 123 provided on the inner peripheral surface of the cam cylinder 120 can rotate the second movable cylinder 140 from the retracted state to the wide end without rotating beyond the limit angle by 60 °. The cam groove 123 provided on the inner peripheral surface of the cam cylinder 120 may be provided so as to be extended to the wide end by rotating 75 ° from the retracted state in accordance with the cam groove 121 on the outer peripheral surface. When the rotation angle of a plurality of cam grooves provided on the inner peripheral surface of 120 is 75 ° in accordance with the cam groove 121 on the outer peripheral surface, the amount of movement in the optical axis direction of the second lens group in this embodiment was considered. At this time, the cam groove for correctly moving the second moving cylinder 140 along the desired movement locus is not established. For this reason, in this embodiment, the cam groove 121 on the outer peripheral surface of the cam cylinder is defined so as to extend the first moving cylinder 110 to the wide end by rotating 75 ° from the retracted state, The shape of the cam groove 123 on the peripheral surface is determined so that the second movable cylinder 140 is extended to the wide end by rotating 60 ° from the retracted state.

FIG. 7 is a view showing the shape of a cam groove formed on the inner peripheral surface of the fixed cylinder.
A key ring 150 shown in FIGS. 3 to 5 is fitted into the fixed cylinder 160, and a linear groove 161 that prohibits rotation of the key ring 150 around the optical axis, and a key follower pin 133 provided on the outer peripheral surface of the intermediate cylinder 130. The cam groove 162 into which the cam follower pin 125 is inserted, and the cam groove 163 through which the cam follower pin 125 embedded in the cam cylinder 120 penetrates the inner peripheral surface and the outer peripheral surface of the fixed cylinder.

  As described above, the cam follower pin 125 implanted in the cam cylinder 120 passes through the cam groove 163 of the fixed cylinder 160 and is fitted in the key groove 171 of the drive cylinder 170. When this lens barrel is in the retracted state (see FIG. 5), the cam follower pin 125 implanted in the cam cylinder 120 is a position of the cam groove 163 of the fixed cylinder 160 indicated by the letters “collapse” in FIG. When the drive cylinder 170 rotates 60 °, the cam follower pin 125 provided on the cam cylinder 120 moves from the “collapsed” position to the “WIDE 60 °” position according to the cam groove 163. Accordingly, the cam cylinder 120 is also rotated by 60 °, and is also advanced forward in the optical axis direction from the “collapsed” position to the “WIDE 60 °” position according to the cam groove 163.

  As described above, the intermediate cylinder 130 is rotatable relative to the cam cylinder 120 and can only move integrally in the optical axis direction. A cam follower pin 133 provided on the intermediate cylinder 130 is fitted in the cam groove 162 on the inner peripheral surface of the fixed cylinder 160. For this reason, the cam follower pin 133 of the intermediate cylinder 130 is moved in the “collapse position” of the cam groove 162 while the cam cylinder 120 is rotated by 60 ° from the “collapse” position to the “WIDE 60 °” position according to the cam groove 163. The intermediate cylinder 130 is rotated integrally with the cam cylinder 120 and rotated 15 ° in the direction opposite to the rotation direction of the cam cylinder 120.

  Further, as described above, the rotation restricting portion 112 provided in the first moving cylinder 110 is fitted in the key groove 131 of the intermediate cylinder 130, so that the first moving cylinder 110 is in the optical axis direction with respect to the intermediate cylinder 130. The relative rotation about the optical axis with respect to the intermediate cylinder 130 is prohibited. Therefore, when the intermediate cylinder 130 rotates 15 ° according to the cam groove 162 on the inner peripheral surface of the fixed cylinder 160, the first moving cylinder 110 also rotates 15 ° in accordance with the rotation of the intermediate cylinder 130.

  A cam follower pin 111 that fits in a cam groove 121 (see FIG. 6A) provided on the outer peripheral surface of the cam cylinder 120 is provided on the inner peripheral surface of the first moving cylinder 110, and the cam cylinder 120 is retracted. During the rotation of 60 ° from the state to the wide end, the intermediate cylinder 130 and the first moving cylinder 110 rotate 15 ° in the direction opposite to the rotation direction of the cam cylinder 120 by 60 °, and the cam cylinder 120 is the first moving cylinder. Therefore, the cam follower pin 111 provided in the first moving cylinder 110 has a cam groove 121 on the outer peripheral surface of the cam cylinder 120 shown in FIG. It will advance between ゜.

  On the other hand, the second lens frame 140 has a key groove 142 that engages with the rectilinear key ring 150, and the rectilinear key ring 150 is fitted in the rectilinear groove 161 (see FIG. 7) of the fixed cylinder 160. Accordingly, the second lens frame 140 is prohibited from rotating with respect to the fixed cylinder 160 and is only allowed to move in the optical axis direction. The second lens frame 140 is provided with a cam follower pin 141 that fits into a cam groove 123 (see FIG. 6B) provided on the inner peripheral surface of the cam cylinder 120, so that the cam cylinder 120 is in a retracted state. When rotated 60 ° to the wide end, the second lens frame 140 also advances straight in the optical axis direction from the 0 ° position to the 60 ° position in accordance with the cam groove 123 shown in FIG. 6B.

  As described above, the cam groove 123 on the inner peripheral surface of the cam cylinder 120 rotates 60 ° from the retracted state to the wide end, and the cam groove 121 on the outer peripheral surface of the cam cylinder 120 changes from the retracted state to the wide end. The contradiction that it is necessary to rotate 75 ° until the intermediate tube 130 and the first movable tube 110 are rotated 15 ° in the opposite direction to the rotation direction of the cam tube 120 while the cam tube 120 is rotated 60 °. It has been solved by. By doing so, an angle θ (see FIG. 6A) of the cam groove 121 on the outer peripheral surface of the cam cylinder 120 can be suppressed within a predetermined angle, and a cam mechanism that operates smoothly is realized.

  When the drive cylinder 170 rotates beyond the wide end toward the tele end, the cam follower pin 125 provided in the cam cylinder 120 moves the cam groove 163 of the fixed cylinder 160 shown in FIG. 7 from the position “WIDE 60 °”. Move to the position “TELE145 °”. The cam groove 163 extends in the circumferential direction between “WIDE 60 °” and “TELE 145 °”. Therefore, in the zooming region between the wide end and the tele end, the cam cylinder 120 and the intermediate cylinder 130 are in the optical axis direction. The cam follower pin 133 of the intermediate cylinder 130 remains in the “photographing position” (see FIG. 7) of the cam groove 162 of the fixed cylinder 160, and the cam cylinder 120 is 85 ° (145 ° at the tele end). -Rotate 60 ° at wide end.

  Meanwhile, the cam follower pin 111 of the first moving cylinder 110 moves from the 75 ° position shown in FIG. 6A to the 160 ° position of the cam groove 121 on the outer peripheral surface of the cam cylinder 120 shown in FIG. 6A. The first lens group 210 moves in the optical axis direction by moving in the optical axis direction according to the groove 121. At the same time, the cam follower pin 141 of the second lens group 140 follows the cam groove 123 from the 60 ° position shown in FIG. 6B of the cam groove 123 on the inner peripheral surface of the cam barrel 120 to the 145 ° position. Accordingly, the second lens group 220 is also moved in the optical axis direction. In this way, the drive cylinder 170 and the cam cylinder 120 are fed to the wide end while rotating 60 degrees from the retracted state, and then the zooming is performed from the wide end to the tele end while rotating 85 degrees.

  FIG. 8 is a block diagram showing a circuit configuration of the digital camera of the present embodiment.

  The digital camera 1 includes a photographing lens 200 having a three-group configuration including a first lens group 210, a second lens group 220, and a third lens group 230 shown in FIGS. 3 to 5, a shutter unit 147, and a CCD solid-state imaging. An element 320 is provided. A subject image formed on the CCD solid-state imaging device 320 via the photographing lens 200 and the shutter unit 147 is converted into an analog image signal by the CCD solid-state imaging device 320. Here, the shutter unit 147 includes a diaphragm for limiting the amount of light irradiated to the CCD solid-state image sensor 320 and a shutter for suppressing the occurrence of smear due to light when reading an analog signal from the CCD solid-state image sensor 320. .

  Further, the auxiliary light emitting unit 12 is provided here, and this auxiliary light emitting unit 600 emits auxiliary light from the auxiliary light emitting unit 12 shown in FIGS. 1 and 2 toward the front of the camera at low luminance. To do. Further, the auxiliary light emitting unit 600 can emit light when necessary other than low luminance.

  The digital camera 1 includes an analog signal processing unit 501, an A / D unit 502, a digital signal processing unit 503, a temporary memory 504, a compression / decompression unit 505, and a built-in memory (or memory card) 506. An image monitor 507 and a drive circuit 508 are provided. The CCD solid-state imaging device 320 is driven at a timing generated by a timing generation circuit (not shown) in the driving circuit 508, and outputs an analog image signal. The drive circuit 508 also includes a drive circuit that drives the photographing lens 200, the shutter unit 147, the auxiliary light emitting unit 600, and the like. The analog image signal output from the CCD solid-state imaging device 320 is subjected to analog signal processing by the analog signal processing unit 501, A / D converted by the A / D unit 502, and digital signal processed by the digital signal processing unit 503. Image data representing an image after digital signal processing is temporarily stored in temporary memory 504. The image data stored in the temporary memory 504 is compressed by the compression / decompression unit 505 and recorded in the built-in memory (or memory card) 506. Depending on the shooting mode, the compression process may be omitted, and recording may be performed directly in the built-in memory (or memory card) 506. Further, the image data stored in the temporary memory 504 is read out to the image monitor 507, whereby the image of the subject is displayed on the image monitor 507.

  Further, the digital camera 1 is provided with a CPU 509 for controlling the entire digital camera 1, an operation switch group 510 including a zoom operation switch and the like, and a shutter button 14, and operates the operation switch group 510. Then, by setting a desired shooting state including setting a desired angle of view and pressing the shutter button 14, a picture is taken, that is, the above-described image data is generated.

1 is an external perspective view of a digital camera that is an embodiment of the present invention. 1 is an external perspective view of a digital camera that is an embodiment of the present invention. It is sectional drawing in the wide end of the lens barrel incorporated in the digital camera shown in FIG. 1, FIG. It is sectional drawing in the tele end of the lens barrel incorporated in the digital camera shown in FIG. 1, FIG. It is sectional drawing in the retracted state of the lens barrel incorporated in the digital camera shown in FIG. It is a figure which shows the shape of the cam groove provided in the cam cylinder. It is a figure which shows the shape of the cam groove formed in the fixed cylinder inner peripheral surface. It is a block diagram which shows the circuit structure of the digital camera of this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Digital camera 12 Auxiliary light emission window 13 Finder objective window 14 Shutter button 100 Lens barrel 110 First moving cylinder 120 Cam cylinder 130 Intermediate cylinder 140 Second lens frame 150 Straight key ring 160 Fixed cylinder 170 Driving cylinder 200 Shooting lens 210 First Lens group 220 Second lens group 230 Third lens group 320 CCD solid-state imaging device

Claims (6)

A lens barrel having a plurality of lens groups each including a first lens group forward in the optical axis direction and a second lens group adjacent to the first lens group, each of which moves in the optical axis direction. In
A first holding member for holding the first lens group;
A second holding member for holding the second lens group;
A cam that rotates at least one of the first holding member and the second holding member relative to the other around the optical axis while moving the first holding member and the second holding member in the optical axis direction. And a lens barrel. The cam mechanism is
A first cam groove for driving the first holding member is formed on one of the outer peripheral surface and the inner peripheral surface, and driving for driving the second holding member on the other of the outer peripheral surface and the inner peripheral surface A cam cylinder in which a second cam groove having a rotation amount different from that of the first cam groove is formed;
An optical axis corresponding to a compensation amount that compensates for a difference in rotational amount required for driving between the first cam groove and the second cam groove with respect to at least one of the first holding member and the second holding member. The lens barrel according to claim 1, further comprising a lens rotation mechanism that relatively rotates around the lens barrel. The lens rotation mechanism is
A first key for restricting rotation of the first holding member;
A second key for restricting rotation of the second holding member;
The first key and the second key are respectively guided in the optical axis direction, and at least one of the first key and the second key is rotated relative to the other around the optical axis by the compensation amount. 3. The lens barrel according to claim 2, further comprising a fixing member on which the first key groove and the second key groove are formed. This lens barrel is a lens barrel that can be retracted and extended and the focal length can be adjusted in the extended state,
The cam mechanism rotates at least one of the first holding member and the second holding member relative to the other around the optical axis only between the retracted state and the extended state, and is in the extended state. 2. The lens barrel according to claim 1, wherein the focal length is adjusted by prohibiting rotation of the first holding member and the second holding member and moving straight.   A light amount control member for controlling the light amount of subject light passing through the lens barrel is provided, wherein the second holding member holds the second lens group and holds the light amount control member. The lens barrel according to claim 1. A lens barrel that can be retracted and extended, and includes a plurality of lens groups each including a first lens group forward in the optical axis direction that moves in the optical axis direction and a second lens group adjacent to the first lens group. In a camera that takes a picture by capturing subject light that has passed through the lens barrel,
The lens barrel is
A first holding member for holding the first lens group;
A second holding member for holding the second lens group;
A cam that rotates at least one of the first holding member and the second holding member relative to the other around the optical axis while moving the first holding member and the second holding member in the optical axis direction. A camera characterized by comprising a mechanism.

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