JP3771552B2 - Zoom lens unit - Google Patents

Description

  The present invention relates to a zoom lens unit having a cam device for adjusting a lens position and performing a zooming operation by advancing and retracting one or a plurality of lens groups in an optical axis direction, and a digital still camera using an imaging device In particular, the present invention relates to a zoom lens unit that can be mounted on a mobile phone or the like because of severe restrictions on the total length such as a camera mounted on a mobile phone and a camera mounted on a portable information terminal.

  As a zoom lens unit having a cam device, for example, a zoom lens barrel that moves a lens group in the optical axis direction by a rotational movement of a cam ring having a cam groove is known (see, for example, Patent Document 1).

The zoom lens barrel according to the patent document 1, a lens barrel of the so-called Daburuheriko id method, a fixed frame having a helicoidal screw to inside diameter is secured to the camera body, screwed inside diameter of the fixed frame and, A first moving frame provided with a helicoid screw or a cam groove on the inner diameter, movable in the optical axis direction, a second moving frame screwed with the inner diameter of the first moving frame and integrated with the first group lens frame; Rotation is constrained by a cam frame that receives a rotational force directly from one moving frame and has a one-sided cam on the inner diameter, and a linear keyway with a fixed frame inner diameter, moves together with the first moving frame, and is used for cam frame guidance. It is comprised by the rectilinear frame which has a cam hole.
JP-A-8-313784

By the way, in recent years, with the diversification of information, an imaging lens is mounted on a cellular phone or a portable information terminal, and the information amount of an image is rapidly increasing due to an improvement in information transmission speed. Various mobile terminals that already have a fixed focus lens and a variable power lens have been proposed.
In order to mount a camera module on this type of portable device, such as a mobile phone or a portable information terminal, the optical (lens) system is extremely compact and can be configured as easily as possible. There must be.

  However, the zoom lens barrel described in Patent Document 1 basically has a configuration in which a lens group is entirely included in a fixed frame, and the lens moving frame is moved in a screwed relationship by screws. Therefore, there is a limit to downsizing, and since it is necessary to be screwed together, the configuration is complicated and the assembly is troublesome.

In addition, with the miniaturization, the image pickup device composed of a CCD, a CMOS sensor or the like is also reduced, and all of the focal length, the lens, the lens frame and the like are reduced. As a result, the accuracy required for the lens unit becomes severe.
Therefore, the optical performance, the eccentricity error, and the tilt error, which have not been a problem with silver halide film cameras, have a great influence on the optical performance.
In spite of such circumstances, in the zoom lens barrel described in Patent Document 1, since the cam ring is likely to be deformed, an eccentricity error and an inclination error are likely to occur, and the lens can be moved smoothly. Disturb.

  The present invention has been made in view of such circumstances, and its purpose is not only to realize downsizing, but also to prevent occurrence of decentration error and tilt error, and allows the lens to move smoothly and realize stable position adjustment. The object is to provide a zoom lens unit.

In order to achieve the above object, according to an aspect of the present invention, a first lens group, a second lens group, and a third lens group are sequentially arranged on the optical axis, the first lens group is fixed, and the second lens is fixed. A zoom lens unit in which the lens group and the third lens group move on the optical axis, wherein the second lens group and the third lens group are moved in the moving region of the second lens group and the third lens group. At least one guide shaft that guides in a direction substantially parallel to the optical axis, the first locked portion that accommodates the second lens group and extends in a direction substantially orthogonal to the optical axis, and the guide shaft are guided. A first lens moving frame formed with a first guided portion and a second locked portion that accommodates the third lens group and extends in a direction substantially orthogonal to the optical axis, and the guide shaft. The second len formed with the second guided portion guided The moving frame, the cam device arranged in parallel with the moving region of the second lens group and the third lens group, the first lens moving frame, and the second lens moving frame are offset. As described above, the cam device includes the first locking portion and the second locking portion. The elastic device is suspended between the first lens moving frame body and the second lens moving frame body. The second lens group and the third lens group are moved along the guide shaft in accordance with the driving state, and the first guided part and the second guided part are moved. each is to have a plurality of bearing portions which the guide shaft is inserted, the two bearing portions included in the same of the guide portion, the two sliding portions tapered to the guide shaft comes into sliding contact is formed, The two bearing portions are shaped so that the sliding contact portion is located on the opposite side across the guide shaft. It is formed in.

  Preferably, the bearing portion of the first guided portion and the bearing portion of the second guided portion are alternately inserted at predetermined intervals with respect to the guide shaft to be inserted. ing.

  Preferably, the first guided portion includes a first bearing portion and a second bearing portion, and the second guided portion includes a third bearing portion and a fourth bearing portion, The first, second, third, and fourth bearing portions are spaced apart from each other with respect to the guide shaft, and the first bearing portion, the third bearing portion, the second bearing portion, and the fourth bearing portion. Inserted in order.

  Preferably, the cam device rotates in accordance with the rotation of the rotating body along the outer surface of the rotating body, and a rotating body that can rotate around an axis substantially parallel to the guide shaft. Formed, the first locked portion is locked, a first cam portion that guides the first locked portion according to rotation, and the rotating body along the outer surface of the rotating body. A second cam portion that is formed to rotate in response to the rotation, the second locked portion is locked, and guides the second locked portion in response to the rotation.

  Preferably, the first cam portion and the second cam portion are formed so as to be included in a belt-like body having a first surface and a second surface facing each other in the optical axis direction, and the first surface is It functions as a first cam part, and the second surface functions as the second cam part.

  Preferably, at least one of the first cam portion and the second cam portion includes a slope portion.

  Preferably, the guide shaft includes a first guide shaft and a second guide shaft arranged in a moving region of the second lens group and the third lens group at a predetermined interval, and the first and second guide shafts The plurality of bearing portions of the second guided portion are guided by the first guide shaft, and the first lens moving frame body is formed with a third guided portion guided by the second guide shaft. The fourth lens moving frame is formed with a fourth guided portion for guiding the second guide shaft.

  According to the present invention, there is an advantage that downsizing can be realized, the lens can be moved smoothly, and stable position adjustment can be realized.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is an external perspective view of the zoom lens unit according to the present invention as viewed from the front side, and FIG. 2 is a partially omitted external perspective view of the zoom lens unit according to the present invention as viewed from the back side. 3 is a front view of the zoom lens unit according to the present invention, and FIG. 4 is a top view of the zoom lens unit according to the present invention.

  As shown in the figure, the zoom lens unit 10 includes a fixed frame 11 that houses main components such as a lens, a guide shaft, and a cam device, a first lens group 121, a second lens group 122, and a third lens. The first lens group 121 is fixed to the fixed frame 11, and the second and third lens groups 122 and 123 are arranged in the fixed frame 11 so as to be movable on the optical axis. An imaging optical system 12, and a guide unit 13 having a first guide shaft 131 and a second guide shaft 132 for guiding the second lens group 122 and the third lens group 123 of the imaging optical system 12 in a direction parallel to the optical axis; A cam device 14 arranged in parallel in the fixed frame 11 with respect to the imaging optical system 12 and an imaging element 151 made up of a CCD or CMOS sensor are arranged so as to include an optical axis as a part of the imaging optical system 12. Have .

Incidentally, In Fig. 1, the optical axis of the imaging optical system 12 is configured such that the Z-axis direction in an orthogonal coordinate system set in FIG., As described in detail later, the second lens group 122 and the third lens group 123 are moved (advanced / retracted) in the optical axis direction according to the rotation of the cam device 14.

For example, in FIG. 1 and FIG. 2, the front side, the rear side, and the lower side of the fixed frame 11 are open, and the lower sides of the left and right sides are attached to the base 15. And the one end part of the 1st guide shaft 131 of the guide part 13 and the 2nd guide shaft 132 is pivotally supported in the position which opposes at about 180 degrees.
On the left side of the upper surface portion 11a of the fixed frame 11, a first opening 111a having a circular cross section communicating with the optical axis direction is formed to fix the first lens group 121 of the imaging optical system 12. It functions as the lens group fixing frame 111.
Further, in parallel with the first lens group fixed frame 111, a bearing portion of a rotating shaft of a rotating body of the cam device 14, a gear train for transmitting a rotational driving force of a motor (not shown) to the rotating body with a predetermined reduction ratio, and the like. Is integrally formed.

5 is a cross-sectional view in the direction of arrows AA in FIG. 4, and FIG. 6 is a cross-sectional view in the direction of arrows BB in FIG.
Hereinafter, a specific configuration example of the imaging optical system 12 according to the present embodiment will be described in association with FIGS. 5 and 6 in addition to FIGS.

As shown in FIGS. 5 and 6, the imaging optical system according to the present embodiment includes a first lens group 121 having a negative refractive power, arranged in order from the object side OBJS, and a positive and negative refraction. A second lens group 122 having a positive refracting power as a whole, a third lens group 123 having a single refracting power, a third lens group 123 having a negative refracting power, an imaging unit 124 provided on the base side, and The aperture portion 125 is disposed on the object side (the first lens group 121 side) of the second lens group 122.
When zooming is performed in the imaging optical system 12, among the first lens group 121, the second lens group 122, and the third lens group 123, the second lens group 122 and the third lens group 123 are on the optical axis. Is moved according to the rotation of the cam device 14.

  As described above, in the present embodiment, the imaging optical system 12 includes one first lens group 121, three second lens groups 122, and one third lens group 123 arranged in order from the object side OBJS. It consists of a total of five lenses.

The first lens group 121 includes, for example, a meniscus lens 1211 having a negative refractive power and having a convex surface on the object side on the first surface.
In this way, by configuring the first lens group 121 with the meniscus lens 1211 having negative refractive power, it becomes easy to suppress distortion.

Since the second lens group 122 is the only group having positive refractive power, a three-lens configuration is adopted to correct various aberrations. Further, when this second lens group 122 glass lens is used, it is smaller and therefore more expensive than a normal lens. Therefore, in order to achieve cost reduction, the three lenses constituting the second lens group 122 are made of plastic lenses.
The three plastic lenses constituting the second lens group 122 include, for example, a positive meniscus lens 1221, a negative meniscus lens 1222, and a positive biconvex lens 1223 from the first lens group 121 side (object side). Is done.
The positive meniscus lens 1221 performs spherical aberration correction satisfactorily, and the lens located at the center of the three lenses is the negative meniscus lens 1222, while suppressing overcorrection of the ellipsoidal curvature generated in the positive lens. By suppressing the occurrence of coma aberration, the performance balance is achieved. By these, aberration fluctuations associated with zooming are suppressed, and high-performance zooming is possible.

Since the third lens group 123 has a single lens configuration, various aberrations need to be corrected here, spherical aberration, coma aberration, astigmatism, distortion correction, and correction of the exit angle at the wide angle end are performed. It is also necessary for.
The third lens group 123 includes a negative lens 1231 having a concave surface on the image surface side, for example.
In the present embodiment, focus adjustment (focus adjustment) is performed by the third lens group 123 and moves from the infinity toward the imaging surface side.
When the third lens group is a positive lens, the distance between the second lens group and the third lens group at the telephoto end must be ensured in order to move toward the object side.
In the present embodiment, since it moves to the image plane side, the distance between the second lens group 122 and the third lens group 123 at the telephoto end can be reduced.
This is one of the factors that make it possible to reduce the size of the variable magnification optical system, and if it is the same size, it is possible to arrange the power without difficulty, enabling higher performance and lowering the eccentricity sensitivity. Yes.

In the imaging unit 124 provided on the base 15 side, a parallel plane plate (cover glass) 152 made of glass and an imaging element 151 made of, for example, a CCD or a CMOS sensor are sequentially arranged from the third lens group 123 side. .
Light from the subject (object) via the imaging optical system is imaged on the imaging surface 151 a of the imaging element 151.

  The imaging optical system having the first lens group 121, the second lens group 122, and the third lens group 123 described above has a telephoto function because the entire optical system has negative, positive, and negative lens configurations. Therefore, the overall length can be shortened.

  The imaging optical system 12 according to the present embodiment having the above-described configuration is downsized so that it can be mounted on a mobile phone or the like.

As described above, the first lens group 121 of the imaging optical system 12 is fixed to the first lens fixed frame 111, and the second lens group 122 is housed and fixed to the first lens moving frame 16, and the third lens. The group 123 is housed and fixed in the second lens moving frame 17.
The first lens moving frame body 16 and the second lens moving frame body 17 are configured such that the first guide shaft 131 and the second guide shaft 132 are guided in the optical axis direction.

  Next, the configurations of the first lens moving frame body 16 and the second lens moving frame body 17 and the arrangement and engagement relationship between the first guide shaft 131, the second guide shaft 132, and the cam device 14 will be described.

  FIG. 7 is a perspective view showing the arrangement and engagement relationships of the first lens moving frame body 16 and the second lens moving frame body 17, the first guide shaft 131, the second guide shaft 132, and the cam device 14 from the front side. FIG. 8 shows the arrangement and engagement relationship between the first lens moving frame body 16 and the second lens moving frame body 17, the first guide shaft 131, the second guide shaft 132, and the cam device 14 from the back side. FIG. 9 is a perspective view showing the arrangement and engagement relationship between the first lens moving frame body 16 and the second lens moving frame body 17, the first guide shaft 131, the second guide shaft 132, and the cam device 14. It is a perspective view shown from the upper surface side.

  In the present embodiment, the first guide shaft 131 is pivotally supported on the fixed frame body 11 so as to be slightly on the front side in the vicinity of the cam device 14, and the second guide shaft 132 includes the first and second guide shafts 132. The lens moving frames 16 and 17 are sandwiched between and are opposed to each other at approximately 180 ° and are pivotally supported by the fixed frame 11 so as to be located slightly on the back side.

The first lens moving frame 16 is formed integrally with the first frame 161 on the first lens group 121 side and the first frame 161 so as to accommodate and fix the second lens group 122 composed of three lenses. The second frame 162 on the three lens group 123 side has a two-stage configuration.
The first lens moving frame body 16 extends in a direction substantially orthogonal to the optical axis from the back side of the first frame body 161 and has a plate shape that is locked to the first cam section 1421 of the cam device 14. The to-be-latched part 163 is formed.
The first lens moving frame body 16 is inserted into and supported by the first guide shaft 131 integrally with the front surface side of the first locked portion 163, and the first guide shaft 131 is rotated according to the rotation of the cam device 14. A first guided portion 164 is formed to be guided.
Further, the first lens moving frame 16 is positioned at a predetermined position of the second frame 162, specifically, at a position facing the formation position of the first locked portion 163 at approximately 180 ° with respect to the second guide shaft. A third guided portion 165 is formed which is inserted into the shaft 132 from the side portion of the shaft and is engaged by being sandwiched so that the second guide shaft 132 is guided according to the rotation of the cam device 14.

The second lens moving frame 17 is formed in a one-stage configuration with plastic or the like in order to accommodate and fix the first lens group 123 composed of one lens.
The second lens moving frame 17 extends in a direction substantially orthogonal to the optical axis from the back side, and has a plate-like second locked portion 171 that is locked to the second cam portion 1422 of the cam device 14. Is formed.
The second lens moving frame 17 is inserted into and supported by the first guide shaft 131 integrally with the front surface side of the second locked portion 171, and the first guide shaft 131 is rotated according to the rotation of the cam device 14. A second guided portion 172 is formed.
Further, the second lens moving frame body 17 is inserted into the second guide shaft 132 from the side of the shaft at a position facing the position where the first locked portion 172 is formed at approximately 180 ° and sandwiched. A fourth guided portion 173 is formed that engages and guides the second guide shaft 132 according to the rotation of the cam device 14.

  In the present embodiment, the first lens moving frame 16 and the second lens moving frame 17 are opposed to the formation positions of the substantially first locked portion 163 and the second locked portion 171 on the front side. Coil spring as an elastic body between the first lens moving frame body 16 and the second lens moving frame body 17 so that the first lens moving frame body 16 and the second lens moving frame body 17 can be stably offset at a position where 18 is suspended.

In the present embodiment, the first guided portion 164 of the first lens moving frame 16 and the second guided portion of the second lens moving frame 17 guided by the first guide shaft 131 in the optical axis direction. Each of the portions 172 is stably guided with a plurality of support points by the first guide shaft 131, and a plurality of bearing portions are formed at predetermined intervals so as to suppress the occurrence of inclination eccentricity as much as possible. .
Specifically, the first guided portion 164 of the first lens moving frame body 16 includes a first bearing portion 1641 and a second bearing portion 1642 that are formed at a predetermined interval in the optical axis direction.
Similarly, the second guided portion 172 of the second lens moving frame body 17 includes a third bearing portion 1721 and a third bearing portion 1722 that are formed at a predetermined interval in the optical axis direction.
The first bearing portion 1641, the second bearing portion 1642, the third bearing portion 1721, and the fourth bearing portion 1722 are spaced apart from the first guide shaft 131 by a predetermined distance, and the first bearing portion 1641. The third bearing portion 1721, the second bearing portion 1642, and the fourth bearing portion 1722 are inserted in this order.
As described above, when the first bearing portion 1641, the second bearing portion 1642, the third bearing portion 1721, and the fourth bearing portion 1722 are alternately inserted into the first guide shaft 131, the size is reduced. Even so, the space between the first bearing portion 1641 and the second bearing portion 1642 and the space between the third bearing portion 1721 and the fourth bearing portion 1722 can be sufficiently secured, and a plurality of support points can be stably provided. In addition, it is possible to sufficiently exhibit the effect of suppressing the occurrence of tilt eccentricity as much as possible.

  Furthermore, in the present embodiment, as described above, a coil spring 18 as an elastic body is suspended between the first lens moving frame body 16 and the second lens moving frame body 17, and the first lens moving frame body 16 and Corresponding to the configuration in which the second lens moving frame body 17 is stably offset, the shapes of the first bearing portion 1641 and the second bearing portion 1642 of the first guided portion 164, and the second covered portion. The third bearing portion 1721 and the fourth bearing portion 1722 of the guide portion 172 are formed so as to have different shapes.

  That is, in the lens driving system having the configuration as shown in FIGS. 10, 11, and 12, the shapes of the first bearing portion 1641 and the second bearing portion 1642 of the first guided portion 164, and the second covered portion. The shapes of the third bearing portion 1721 and the fourth bearing portion 1722 of the guide portion 172 are formed, for example, as shown in FIGS.

Specifically, the shapes of the first bearing portion 1641 and the second bearing portion 1642 formed on the same first guided portion 164 are formed as follows.
That is, the first bearing portion 1641 related to the point A in FIG. 11 is formed in a substantially fan shape as shown in FIG. 13A, and is tapered outside the first guide shaft 131 (on the side where the cam device 14 is arranged). Slidable contact portions 1641a and 1641b are formed, and an arcuate portion 1641c is formed inside the first guide shaft 131 (on the side where the imaging optical system 12 is disposed).
On the other hand, the second bearing portion 1642 related to the point C in FIG. 11 is formed in a substantially fan shape as shown in FIG. ) Are formed with tapered sliding contact portions 1642a and 1642b, and an arcuate portion 1642c is formed on the outer side of the first guide shaft 131 (on the side where the cam device 14 is disposed).
That is, the first bearing portion 1641 and the second bearing portion 1642 are formed in such a shape that the sliding contact portion is located on the opposite side across the first guide shaft 131.
As a result, even if the first lens moving frame body 16 and the second lens moving frame body 17 are biased by the coil spring 18, the first lens moving frame body 16 is in a justified state with respect to the first guide shaft 131. It is released and is guided stably along the substantial axis without tilting.

The shapes of the third bearing portion 1721 and the fourth bearing portion 1722 formed in the same first locked portion 172 are formed as follows.
That is, as shown in FIG. 13B, the third bearing portion 1721 related to the point B in FIG. 11 is formed in a substantially fan shape, and is tapered inside the first guide shaft 131 (on the side where the imaging optical system 12 is disposed). The slidable contact portions 1721a and 1721b are formed, and an arcuate portion 1721c is formed outside the first guide shaft 131 (on the side where the cam device 14 is disposed).
On the other hand, as shown in FIG. 13D, the fourth bearing portion 1722 related to the point D in FIG. 11 is formed in a substantially fan shape and is outside the first guide shaft 131 (on the side where the cam device 14 is disposed). Tapered sliding contact portions 1722a and 1722b are formed, and an arcuate portion 1722c is formed inside the first guide shaft 131 (on the side where the imaging optical system 12 is disposed).
In other words, the third bearing portion 1721 and the fourth bearing portion 1722 are formed in such a shape that the sliding contact portion is located on the opposite side across the first guide shaft 131.
As a result, even if the first lens moving frame body 16 and the second lens moving frame body 17 are biased by the coil spring 18, the second lens moving frame body 17 is shifted to the first guide shaft 131. It is released and is guided stably along the substantial axis without tilting.

  Next, the cam apparatus 14 in this embodiment is demonstrated.

  14 and 15 are partially cutaway perspective views showing a state in which the cam device according to the present embodiment is pivoted on the fixed frame body, and FIG. 16 is an overall cross-sectional structure of the cam device according to the present embodiment. FIG. 17 is a cross-sectional view of the shaft center portion of the cam device according to the present embodiment.

As shown in FIG. 8 and the like, the cam device 14 includes a rotating body 141 that can rotate about a rotating shaft 1411 that is substantially parallel to the first guide shaft 131 and the second guide shaft 132, and an outer surface of the rotating body 141. Thus, the first locking portion 163 of the first lens moving frame 16 is locked, and the first locked portion is rotated according to the rotation. A first cam portion 1421 that guides 163, and a second locked portion of the second lens moving frame 17 that is formed to rotate along the outer surface of the rotating body 141 in accordance with the rotation of the rotating body 141. A belt-like body 142 is formed, which includes a second cam portion 1422 that is engaged with the second engaged portion 171 in accordance with rotation.
The belt-like body 142 has a first surface 142a and a second surface 142b that face each other in the optical axis direction, the first surface 142a functions as the first cam portion 1421, and the second surface 142b serves as the second cam portion. Function.

That is, as shown in FIG. 8, the band-like body 142 has a slope from the rear end side toward the front end portion and is formed in a spiral shape, and the front end side is the first surface 142 a and the rear end portion. The side constitutes the second surface 142b.
The width of the belt-like body 142 is such that the first locked portion 163 formed on the first lens moving body 16 and the second locked portion 171 formed on the second lens moving frame 17 are in the optical axis direction. Is set to be substantially equal to the interval of.
With such a configuration, the first lens moving frame 16 and the second lens moving frame 17 are biased by the coil spring 18, so that the first lens moving body 16 formed on the first lens moving body 16 has the first structure. The second surface 171 formed on the locking portion 163 and the second lens moving frame 17 sandwiches the first surface 142a and the second surface 142b of the belt-like body 142, and the first surface 142a The second surface 142b, that is, the first cam portion 1421 and the second cam portion 1422 can be stably held.
Therefore, the first locked portion 163 formed on the first lens moving body 16 and the second locked portion 171 formed on the second lens moving frame 17 are connected to the first surface 142a of the belt-shaped body 142. Further, it is not necessary to fix the second surface 142b with screws or the like, and the assembly itself is simple.

  The first surface 142a and the second surface 142b of the belt-shaped body 142 forming the slope are the first locked portions 163 guided by the first surface 142a and the second surface 142b (first cam portion or second cam portion). And steps corresponding to the functions of the second lens group 122 and the third lens group 123 housed in the first lens moving frame 16 and the second lens moving frame 17 in which the second locked portion 171 is formed, respectively. Is formed.

Further, as shown in FIG. 14 and FIG. 15, the cam device 14 is provided with a gear 1412 that rotates at the distal end under the rotational force of a motor (not shown).
For example, as shown in FIG. 18, the gear 1412 is engaged with a gear train 19 that transmits a rotational driving force of a motor (not shown) with a predetermined reduction ratio.

  In the cam device 14, as shown in FIGS. 16 to 17, the rotation of the rotating body 141 is performed in order to obtain the positional accuracy of the first lens moving frame body 16 and the second lens moving frame body 17 to be driven. The front end portion 1411a and the rear end portion 1411b of the shaft 1411 are respectively supported by a front end portion bearing portion 143 and a rear end portion bearing portion 144, and the front end portion 1411a is given a predetermined force by a coil spring 145 as an urging means. It is biased toward the tip end bearing portion 143 with a force and is offset.

In the present embodiment, the front end portion 1411a and the rear end portion 1411b of the rotating shaft 1411 are formed so as to be in substantially point contact with the front end portion bearing portion 143 and the rear end bearing portion 144.
Specifically, at the center portion of the rotating shaft 1411, a one-sided coil spring 145 as an urging means has one end abutting against the inner wall of the rotating shaft 1411 on the front end portion 1411 a side, and the coil spring 145 and the rear end bearing portion 144. An intermediate body 146 that is substantially point-contacted with the rear end bearing portion 144 is disposed between the two.
The intermediate body 146 has a substantially spherical shape at least on the side in contact with the rear end bearing portion 144, and is configured to realize point contact. In the present embodiment, a sphere is used as the intermediate 146.

In the cam device 14 having such a configuration, the rotating body 141 is rotationally driven by a motor (not shown), and the first locked portion 163 and the second locked portion 171 are the first surface 142a of the belt-like body 142 and The second surface 142b is stably guided.
In this case, in the rotating body 141, the rotating shaft 1411 has its tip portion 1411a biased toward the tip bearing portion 143 with a predetermined biasing force by a coil spring 145 as a biasing means. The positional accuracy of the first lens moving frame body 16 and the second lens moving frame body 17 that are the driving targets can be kept high, and high-precision lens driving is realized.

As described above, according to the present embodiment, the imaging optical system is a variable power lens having a three-group configuration. The first lens group 121 has one lens, the second lens group 122 has three, Since the three lens groups 123 are configured as a single lens and all the second lens groups 122 are made of plastic, the entire length of the optical system can be shortened. The diameter of the lens can be reduced, and the cost can be reduced.
In the aberration correction, the lens arrangement is optimized by optimizing the power arrangement of each lens group. Further, the lens arrangement is further reduced by appropriately arranging aspheric surfaces in the second lens group 122 and the third lens group 123. realizable. By optimizing these conditions, there is an advantage that the distortion can be further reduced with high performance in spite of a compact variable power lens.
Further, in the present embodiment, the focus adjustment is performed by the third lens group 123 and moves toward the imaging surface side from the infinity to the closest position, so that the second lens group 122 and the third lens group 123 at the telephoto end are The distance can be reduced. As a result, the variable magnification optical system can be made compact, and if it is the same size, it is possible to arrange the power without difficulty, and it is possible to achieve higher performance and lower decentration sensitivity.

In addition, since the three plastic second lens groups 122 have a positive meniscus lens, a negative meniscus lens, and a positive biconvex lens configuration, spherical aberration correction can be satisfactorily performed with the positive meniscus lens. In the negative meniscus lens, it is possible to suppress overcorrection of the curvature of field that occurs in the positive lens, and in parallel to this, it is possible to suppress the occurrence of coma aberration. As a result, it is possible to balance performance, and there is an advantage that high-performance zooming is possible by suppressing aberration fluctuations accompanying zooming.

  In addition, in the relationship between the focal lengths (fl, f2, f3) of each lens unit and the focal length fw at the wide-angle end where the combined power is strong, by taking the power balance of each lens unit, high-performance and compact zooming A lens can be realized.

  By defining the condition of the exit pupil position with respect to the restriction of the incident angle to the image sensor 151 as a desired condition, it is possible to relax the restriction of the exit pupil while being wide-angle and compact.

  In the zoom lens unit 10 equipped with the imaging optical system 12 that can be downsized (compacted) in this way, the first lens moving frame body 16 and the second lens moving frame body 17 are substantially first on the front side. The first lens so that the first lens moving frame body 16 and the second lens moving frame body 17 are stably offset at a position opposite to the position where the locked section 163 and the second locked section 171 are formed. A coil spring 18 as an elastic body is suspended between the moving frame body 16 and the second lens moving frame body 17, and the first lens moving frame body 16 is guided in the optical axis direction by the first guide shaft 131. Since each of the first guided portion 164 and the second guided portion 172 of the second lens moving frame body 17 has a plurality of bearing portions formed at predetermined intervals, the first guide shaft 131 is provided. Stable with multiple support points The first guide shaft 131 is spaced apart from the first guide shaft 131 so as to suppress the occurrence of tilt eccentricity as much as possible, and the first bearing portion 1641, the third bearing portion 1721, and the second bearing portion 1642 are provided. And the fourth bearing portion 1722 are inserted in this order, so that there is a sufficient interval between the first bearing portion 1641 and the second bearing portion 1642 and between the third bearing portion 1721 and the fourth bearing portion 1722. It is possible to provide a plurality of support points and to be stably guided, and to sufficiently exhibit the effect that the occurrence of tilt eccentricity and the like can be suppressed as much as possible.

Further, in the present embodiment, a coil spring 18 as an elastic body is suspended between the first lens moving frame body 16 and the second lens moving frame body 17, and the first lens moving frame body 16 and the second lens moving frame. Corresponding to the configuration in which the body 17 is stably displaced, the shapes of the first bearing portion 1641 and the second bearing portion 1642 of the first guided portion 164 and the second guide portion 172 The three bearing portions 1721 and the fourth bearing portion 1722 are formed to have different shapes.
Thereby, even if the first lens moving frame body 16 and the second lens moving frame body 17 are biased by the coil spring 18, the first lens moving frame body 16 and the second lens moving frame body 17 are moved to the first guide shaft. It is possible to release the justified state with respect to 131 and to stably guide it along substantially the axis without tilting.

In the cam device 14 having such a configuration, the rotating body 141 is rotationally driven by a motor (not shown), and the first locked portion 163 and the second locked portion 171 are the first surface 142a of the belt-like body 142 and The second surface 142b is stably guided, and the rotating body 141 has the rotating shaft 1411 urged toward the tip end bearing portion 143 with a predetermined urging force by the coil spring 145 as the tip end portion 1411a. Since they are offset, it is possible to keep the positional accuracy of the first lens moving frame 16 and the second lens moving frame 17 to be driven high, and there is an advantage that highly accurate lens driving can be realized.

  As described above, according to the present embodiment, it is possible to provide a zoom lens unit that can realize downsizing, hardly cause an eccentricity error and an inclination error, can move the lens smoothly, and can realize stable position adjustment. it can.

It is the external appearance perspective view seen from the front side of the zoom lens unit concerning the present invention. FIG. 3 is a partially omitted external perspective view of the zoom lens unit according to the present invention as viewed from the back side. 1 is a front view of a zoom lens unit according to the present invention. It is a top view of the zoom lens unit according to the present invention. It is sectional drawing in the AA arrow direction of FIG. It is sectional drawing in the BB arrow direction of FIG. It is a perspective view which shows arrangement | positioning and engagement relation of the 1st lens moving frame body which concerns on this embodiment, a 2nd lens moving frame body, a 1st guide shaft, a 2nd guide shaft, and a cam apparatus from the front side. It is a perspective view which shows arrangement | positioning and engagement relation of the 1st lens moving frame body and 2nd lens moving frame body which concern on this embodiment, a 1st guide shaft, a 2nd guide shaft, and a cam apparatus from the back side. It is a perspective view which shows arrangement | positioning and engagement relation of the 1st lens moving frame body which concerns on this embodiment, a 2nd lens moving frame body, a 1st guide shaft, a 2nd guide shaft, and a cam apparatus from the upper surface side. It is a top view which shows the lens drive system which concerns on this embodiment, Comprising: The shape of the 1st bearing part and the 2nd bearing part of a 1st to-be-latched part, and the 3rd bearing part of a 2nd to-be-latched part It is a figure for demonstrating the shape of a 4th bearing part. It is a side view which shows the lens drive system which concerns on this embodiment, Comprising: The shape of the 1st bearing part and the 2nd bearing part of a 1st to-be-latched part, and the 3rd bearing part of a 2nd to-be-latched part It is a figure for demonstrating the shape of a 4th bearing part. It is a perspective view which shows the lens drive system which concerns on this embodiment, Comprising: The shape of the 1st bearing part and the 2nd bearing part of a 1st to-be-latched part, and the 3rd bearing part of a 2nd to-be-latched part It is a figure for demonstrating the shape of a 4th bearing part. For explaining the shapes of the first bearing portion and the second bearing portion of the first locked portion and the shapes of the third bearing portion and the fourth bearing portion of the second locked portion according to the present embodiment. FIG. It is a partially cutaway perspective view which shows the state which the cam apparatus which concerns on this embodiment is pivoted by the fixed frame body from the upper surface side. It is a partially cutaway perspective view which shows the state which the cam apparatus which concerns on this embodiment is pivoted by the fixed frame body from the lower surface side. It is a perspective view showing a part of the entire cross-sectional structure of the cam device according to the present embodiment. It is sectional drawing of the axial center part of the cam apparatus which concerns on this embodiment. It is sectional drawing of the axial center part and drive part of the cam apparatus which concern on this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Zoom lens unit, 11 ... Fixed frame body, 12 ... Imaging optical system, 121 ... 1st lens group, 122 ... 2nd lens group, 123 ... 3rd lens, 13 ... Guide part, 131 ... 1st guide shaft, 132 ... 2nd guide shaft, 14 ... Cam apparatus, 141 ... Rotating body, 1411 ... Rotating shaft, 1411a ... Tip part, 1411b ... Rear end part, 142 ... Band-shaped body, 142a ... 1st surface, 142b ... 2nd surface, 1421 ... 1st cam part, 1422 ... 2nd cam part, 143 ... Front end part bearing part, 144 ... Rear end bearing part, 145 ... Coil spring, 15 ... Base, 151 ... Imaging element 151, 16 ... 1st lens movement Frame body 161 ... 1st frame body 162 ... 2nd frame body 163 ... 1st to-be-latched part, 164 ... 1st to-be-guided part, 1641 ... 1st bearing part, 1642 ... 2nd bearing part, 165 ... Third guided part, 17 ... Second lens Moving frame body, 171... Second locked portion, 172... Second guided portion, 1721... Third bearing portion, 1722... Fourth bearing portion, 173.

Claims (7)

The first lens group, the second lens group, and the third lens group are sequentially arranged on the optical axis, the first lens group is fixed, and the second lens group and the third lens group move on the optical axis. Zoom lens unit
At least one guide shaft for guiding the second lens group and the third lens group in a direction substantially parallel to the optical axis in a moving region of the second lens group and the third lens group;
A first lens moving frame in which a first locked portion that accommodates the second lens group and extends in a direction substantially orthogonal to the optical axis and a first guided portion that guides the guide shaft are formed. Body,
A second lens moving frame in which a second locked portion that accommodates the third lens group and extends in a direction substantially orthogonal to the optical axis and a second guided portion that guides the guide shaft are formed. Body,
A cam device arranged in parallel with respect to the movement region of the second lens group and the third lens group;
An elastic body suspended between the first lens moving frame body and the second lens moving frame body so as to shift the first lens moving frame body and the second lens moving frame body together;
Have
The cam device is
The first locking portion and the second locking portion are locked, and each of the second lens group and the third lens group is moved along the guide shaft according to a driving state,
The first of each of the guide portion and the second guided portion may have a plurality of bearing portions which the guide shaft is inserted, the two bearing portions included in the same of the guide portion, the guide shaft Two slidable contact portions that are in sliding contact with each other are formed, and the two bearing portions are formed in such a shape that the slidable contact portions are located on opposite sides of the guide shaft. Zoom lens unit. The bearing portion of the first guided portion and the bearing portion of the second guided portion are respectively inserted at predetermined intervals and alternately with respect to the guide shaft to be inserted. The zoom lens unit according to claim 1, wherein: The first guided portion has a first bearing portion and a second bearing portion,
The second guided portion has a third bearing portion and a fourth bearing portion,
The first, second, third, and fourth bearing portions are spaced apart from each other with respect to the guide shaft, and the first bearing portion, the third bearing portion, the second bearing portion, and the fourth bearing are provided. The zoom lens unit according to claim 1, wherein the zoom lens unit is inserted in the order of the parts. The cam device is
A rotating body rotatable around an axis substantially parallel to the guide shaft;
It is formed so as to rotate according to the rotation of the rotating body along the outer surface of the rotating body, the first locked portion is locked, and the first locked portion is moved according to the rotation. A first cam portion for guiding;
It is formed to rotate according to the rotation of the rotating body along the outer surface of the rotating body, the second locked portion is locked, and the second locked portion is moved according to the rotation. A zoom lens unit according to any one of claims 1 to 3, further comprising a second cam portion for guiding. The first cam portion and the second cam portion are formed so as to be included in a belt-like body having a first surface and a second surface facing each other in the optical axis direction, and the first surface is the first cam portion. The zoom lens unit according to claim 4, wherein the second surface functions as the second cam portion. 6. The zoom lens unit according to claim 4, wherein at least one of the first cam portion and the second cam portion includes a slope portion. The guide shaft includes a first guide shaft and a second guide shaft arranged in a moving region of the second lens group and the third lens group at a predetermined interval,
The plurality of bearing portions of the first and second guided portions are guided by the first guide shaft,
The first lens moving frame is formed with a third guided portion for guiding the second guide shaft,
The zoom lens unit according to any one of claims 1 to 6, wherein the second lens moving frame is formed with a fourth guided portion for guiding the second guide shaft. .

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