JP2005077914A - Lens unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lens unit which can be made thin and small-sized and has its constitution simplified, and is suitably applied to a very small camera. <P>SOLUTION: An imaging element 1 is mounted on a lens part 12 of a base body 10. Guide parts 31, ... at the outer periphery of a lens frame body 30 are fitted onto guide pins 5, ... erected on the base body 10, to make the lens 2 mounted on the lens frame body 30 face the image element 1. A stepping motor 7 is arranged at a drive part 11 of the base body 10, and the tip of an output shaft 29 is formed into a lead screw 3. A cam member 6 is so arranged that the tilt surface of a wedge-like body 60 moves overlapping the top surface of the lens frame body 30 and a screw streak is formed at an edge of an association piece 61 projecting from the body 60 at right angles for engaging with the lead screw 3. The cam member 6 moves linearly in a direction perpendicular to the optical axis L, as the output shaft rotates and reverses, and the lens frame body 30 is pressed to move along the optical axis L. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a lens unit that mechanically moves a lens system by driving a motor. More specifically, the present invention relates to downsizing and improvement of an operation configuration of a drive unit in consideration of mounting on a camera-equipped mobile phone or the like.

  Various lens units have been proposed that mechanically move the lens system by motor drive. And as a structure which uses a cam member for a drive part, what is seen by patent document 1, 2, for example is known.

  The invention disclosed in Patent Document 1 is a configuration using a disc-shaped cam member, and the cam member is attached to the rotation shaft, and the outer cam surface is linked to the surface of the lens frame in the optical axis direction. By rotating the cam member, the lens frame body is moved in the optical axis direction along a locus following the outer cam surface.

The invention disclosed in Patent Document 2 is a configuration using a cam member having an inclined surface, and the cam surface is a cam member provided with respect to a surface in the optical axis direction of the ring member. The lens frame is arranged so as to overlap with the optical axis direction, and the ring member is rotationally driven to move the lens frame in the optical axis direction along a locus following the cam surface.
JP-A-9-43484 JP 2000-47087 A

  However, such a conventional lens unit has the following problems. That is, in the invention disclosed in Patent Document 1, the cam member is arranged so as to project in the optical axis direction in association with the lens frame, and the size in the optical axis direction becomes large. Further, in the invention disclosed in Patent Document 2, since the ring member having the cam surface and the lens frame are arranged so as to overlap in the optical axis direction, this also increases the dimension in the optical axis direction, thereby reducing the size. It is difficult to plan.

  On the other hand, in recent years, mobile phones incorporating ultra-compact cameras have become widespread, and these ultra-compact cameras are severely limited in size and shape, and the lens unit mounted on them needs to be compact, especially in the direction of the optical axis. The demand for is high.

  The present invention solves the above-described problems, and an object of the present invention is to provide a lens unit that can be applied to an ultra-compact camera by realizing a reduction in thickness of the lens unit in the optical axis direction and simplification of a drive unit configuration. There is.

  In order to achieve the above-described object, the lens unit according to the present invention is a lens unit that supports the lens so as to face the imaging element on the base body side and is movable in the optical axis direction, and is moved by a driving unit that performs linear driving. And at least one guide pin extending in the optical axis direction is disposed, and the guide pin is linked to a lens frame on which the lens is mounted so as to be movable, and the wedge is supported on the lens frame. An inclined surface of the cam member is disposed so as to be contactable, and driving means for moving the cam member in a direction orthogonal to the optical axis is provided. The cam member is linearly moved by the driving means to push the lens frame. It was configured to move.

  Preferably, biasing means such as a spring for pressing the lens frame toward the cam member is provided. The drive means uses a drive source as a motor to form a lead screw at the tip of the output shaft, and the cam member is provided with a lead nut that engages with the lead screw or a screw thread that becomes a lead nut, and the output The cam member can be moved linearly as the shaft rotates. Further, the motor may be a stepping motor, preferably a flat stepping motor having a stator coil on both sides of the rotor. Furthermore, the tip end portion of the cam member can be set to overlap with the outer edge portion of the lens frame in the initial state. In this case, it is more preferable that a flat portion is formed at the tip portion of the cam member, and the flat portion is used as the overlapping portion.

  Further, a box-shaped case main body for storing the lens units having the respective configurations described above is further provided, and the cam member is disposed so as to be inserted into a gap formed between the lens frame body and the case main body. You can also. Preferably, a slight space (gap) is formed between the cam member and the case main body. In other words, if there is no such space and the cam member and the case body are in surface contact, the frictional force on the contact surface will increase, and smooth movement may not be possible (in this case, at least one of the contact surfaces has a low friction coefficient). However, by providing a slight space, when the cam member moves, the cam member rotates by the amount of the space and the side edge of the cam member and the case main body come into line contact.

  Further, it is preferable that the number of guide pins is two or less. Preferably, the number of guide pins is one, and a rotation prevention mechanism for the lens frame (for example, a part of the lens frame and a part of the base are engaged). It is to provide. Furthermore, it is more preferable that one of the guide pins is disposed in the vicinity of the contact portion between the inclined surface of the cam member and the lens frame.

  By adopting such a configuration, in the present invention, since the driving means is configured to move the cam member in a direction orthogonal to the optical axis, there is no member projecting greatly in the optical axis direction, and the dimension in the optical axis direction can be kept low. In addition, since the wedge-shaped cam member is simply moved linearly and the lens frame is pushed and moved, the relationship between the components is simple, and the shape of each component is simple.

  If a stepping motor is used as the drive source, the lens movement amount (resolution) per step is easily determined from the motor rotation angle, cam member tilt angle and lead screw thread pitch per step. it can. For this reason, it is easy to design to a desired resolution, the degree of design freedom is high, and there is an advantage in meeting various design conditions. The position of the lens can be controlled by controlling the number of steps.

  Furthermore, if the shape of the stepping motor is a flat shape having stator coils on both sides of the rotor, the size of one direction can be reduced, and the motor can be configured so that the reduced size is the same direction as the optical axis. By arranging the lens unit, the lens unit is thinned.

  Further, if the tip end portion of the cam member is overlapped with the outer edge portion of the lens frame body, it can be overlapped in the initial state, and it is possible to prevent the driving operation from being disabled without losing the linkage relationship therebetween.

  Further, when the cam member is inserted and disposed in the gap between the case main body and the lens frame, the reaction force from the lens frame can be received by the case main body, and excessive rotation of the cam member is prevented. be able to.

  Furthermore, the guide pin is linked to the lens frame, and friction is generated at that portion. For this reason, it is preferable that the number of lenses is small because malfunction of the lens frame due to friction is less likely to occur. Further, when the guide pin is disposed in the vicinity of the driving action point of the lens frame, that is, in the vicinity of the contact portion between the inclined surface of the cam member and the lens frame, the action point and the fulcrum are close to each other, and stress such as galling is reduced. Therefore, it is preferable that the friction can be further reduced.

  In the lens unit according to the present invention, the dimension in the optical axis direction can be kept low, and as a result, the unit can be reduced in thickness and thickness. Further, the relationship between the cam member and the lens frame is simple, and the shape and the like of each component are simple. Therefore, the configuration can be simplified, and application to a micro camera is possible.

  FIGS. 1A and 1B show a first embodiment of the present invention. In the present embodiment, the lens unit is mounted with the image pickup device 1 such as a CCD mounted on the base body 10, supports the lens 2 so as to face the image pickup device 1, and drives the wedge-shaped cam member 6 linearly. Is configured to move in the direction of the optical axis (L).

  The base body 10 is a substantially rectangular box-shaped case, and forms a drive unit 11 serving as a base unit of drive means and a lens unit 12 serving as a base unit of an optical system. A rectangular recess 13 is formed below the lens portion 12. The image sensor 1 such as a CCD is disposed in the recess 13, and the center of the recess 13 is the optical axis L. The lens portion 12 is provided with a guide pin 5 extending along the optical axis. In the present embodiment, three guide pins 5 are provided, and the guide portions 31 of the lens frame 30 are fitted to the guide pins 5 so as to be movable in the axial direction, thereby guiding them in the optical axis direction. Rotation stops when driving in a straight line.

  A stepping motor 7 is disposed in the drive unit 11. The stepping motor 7 has a flat configuration having stator coils on both sides of the rotor, and is mounted on the drive unit 11 in a state of being housed in the housing case 70. Then, a lead screw 3 is formed by cutting a screw thread at the tip of the rotor shaft (output shaft 29).

  The lens frame 30 is provided with a cylindrical guide portion 31 on the outer periphery of an annular main body, and the lens 2 is mounted in a through hole 33 in the center of the main body. That is, by forming guide portions 31 of a shape engaging with the guide pins 5 on the base body 10 side, and engaging the guide portions 31 with the guide pins 5 movably. The lens frame 30 is mounted so as to be movable in the optical axis direction.

  As shown in FIG. 2, the cam member 6 is configured by extending a linkage piece 61 perpendicularly to the wedge-shaped main body 60. A thread is provided on the end edge of the linkage piece 61, and the thread is a lead that fits into the lead screw 3 on the output shaft 29 side. The storage case 70 is provided with a cut portion 71, and the main body 60 of the cam member 6 is movably fitted in the cut portion 71, and the cam member 6 is linearly moved while being guided on both sides.

  In the present embodiment, the cam member 6 that moves linearly adopts an arrangement in which the inclined surface moves overlapping the upper surface of the lens frame 30. For this reason, the spring member 8 is disposed below the lens frame 30 to press the lens frame 30 toward the cam member 6.

  In addition, the cam member 6 is set so that the tip portion of the cam member 6 overlaps with the outer edge portion of the lens frame 30 in the initial state, and the cam member 6 is set to have an inclined surface of 45 ° or less. In the initial state, by superimposing the tip portion of the cam member 6 on the outer edge portion of the lens frame 30, it is possible to prevent the linkage relationship between the two members from being removed and the driving operation from being disabled. Furthermore, by setting the inclination of the inclined surface of the cam member 6 to 45 ° or less, the amount of pushing movement of the lens frame 30 accompanying the linear movement of the cam member 6 can be reduced correspondingly, and the resolution for moving the lens frame is accordingly increased. Can be raised. Furthermore, the spring member 8 uses a coil spring in the present embodiment. The spring member 8 may be appropriately changed, for example, a leaf spring or an elastic member such as rubber.

  Accordingly, as a driving means, the lead screw 3 provided on the output shaft 29 and the end edge portion (lead nut) of the linkage piece 61 mesh with each other, and the lead nut, that is, the cam member 6 linearly moves as the output shaft 29 rotates forward and backward. Since the inclined surface of the cam member 6 moves overlapping the upper surface of the lens frame 30, the lens frame 30 is pushed and moves in the optical axis direction. Then, the imaging point (focal point) changes with respect to the image sensor 1 in accordance with the positional relationship of the lens 2 aligned with the optical axis L, and a focusing operation can be performed.

  Thus, since the drive means is configured to move the cam member 6 in the direction orthogonal to the optical axis L, there is no member projecting greatly in the optical axis L direction, and the dimension in the optical axis L direction can be kept low. As a result, the unit can be reduced in thickness and thickness.

  In addition, since the wedge-shaped cam member 6 is simply moved linearly and the lens frame 30 is pushed and moved, the relationship between the components is simple. Therefore, the shape of each component is simple. Therefore, the configuration can be simplified and application to a micro camera is possible.

By the way, the resolution X by moving the lens 2 by the stepping motor 7 is:
X = (A / 360) × P × tan θ
Where A, P, and θ are
A: One-step rotation angle P of the stepping motor 7: Screw pitch θ of the lead screw 3: Angle of the inclined surface of the cam member 6. Therefore, the resolution X can be appropriately set by changing the variables A, P, and θ in the relational expression. Therefore, it is easy to design to a desired resolution X, the degree of freedom in design is high, and there is an advantage in meeting various design conditions. Note that the design value of the lens frame 30 is assumed to be a design value of, for example, 1 mm or less, and an ultra-small lens unit that is in the order of lens movement.

  3 (a) and 3 (b) show a second embodiment of the present invention. In the second embodiment, a configuration in which only one guide pin 5 is provided is employed. A guide rail 14 is provided on the base portion 10 along the optical axis L, and a protruding portion 32 is formed on the lens frame 30 at a position facing the guide rail 14, and the protruding portion 32 is fitted to the guide rail 14. This prevents rotation when driving in a straight line. In addition, the same code | symbol is attached | subjected to the component similar to 1st Embodiment mentioned above, and the description is abbreviate | omitted.

  Further, in the present embodiment, the guide pin 5 is disposed in the vicinity of the cam member 6, and the inclined surface of the cam member 6 that moves linearly overlaps the upper surface of the lens frame 30, as in the first embodiment. Since the moving arrangement is adopted, the spring member 8 is arranged concentrically with the guide pin 5 on the lower side of the lens frame 30 to press the lens frame 30 toward the cam member 6.

  As shown in FIG. 4, the cam member 6 has a hole formed in the lead nut 4 by drilling a hole in the connecting piece 61 and providing a thread. Then, the lead nut 4 is meshed with the lead screw 3 provided on the output shaft 29, and the rotation operation is converted into the linear operation.

  That is, since the guide pin 5 is fitted into the guide hole of the lens frame 30, friction is generated at the fitting portion when the lens frame 30 is driven to move. In order to reduce this friction, the guide pins 5 are preferably provided in the vicinity of the drive action point, and the number of arrangement is preferably reduced. For this reason, the present embodiment employs a configuration in which only one guide pin 5 is provided and disposed in the vicinity of the cam member 6. For this reason, the friction can be reduced correspondingly, and the drive source can have a low output, which is advantageous for further miniaturization.

  The operation of the driving means is the same as that of the first embodiment. The lead nut 4 meshes with the lead screw 3 provided on the output shaft 29, and the lead nut 4, that is, the cam member 6 is moved along with the forward and reverse rotation of the output shaft 29. Since the cam member 6 moves linearly and the inclined surface of the cam member 6 overlaps with the upper surface of the lens frame 30, the lens frame 30 is pushed and moves in the optical axis direction.

  5 (a) and 5 (b) show a third embodiment of the present invention. In the third embodiment, a configuration is adopted in which two guide pins 5 are provided, one is arranged in the vicinity of the cam member 6, and the other one is provided at a symmetrical position on the opposite side with respect to the optical axis L to be a straight line. It is used as a detent when driving. In addition, the same components as those in the first embodiment described above are denoted by the same reference numerals, and the description thereof is omitted.

  Contrary to the first embodiment, the cam member 6 that moves linearly adopts an arrangement in which the inclined surface moves overlapping the lower surface of the lens frame 30. For this reason, the spring member 8 is disposed concentrically with the guide pin 5 between the upper surface side of the lens frame 30 and the lid of the base body 10, and presses the lens frame 30 toward the cam member 6.

  A flat portion is formed at the distal end portion of the cam member 6, and the flat portion is used as an overlapping portion with respect to the lower surface of the lens frame 30. Further, the lower surface side of the lens frame 30 is formed by projecting a rounded corner portion 34 with no corners on its outer edge, and the rounded corner portion 34 serves as a contact portion with the cam member 6.

  The operation of the driving means is the same as in the first embodiment, but here the inclined surface of the cam member 6 moves overlapping the lower surface of the lens frame 30, so that the lens frame 30 is pushed. Move in the direction of the optical axis.

  Thus, by forming the flat portion at the tip portion of the cam member 6, the flat portion is used as the overlapping portion, so that it is possible to more reliably prevent the driving operation from being disabled. In addition, since the rounded corner portion 34 with no corners is formed on the outer edge portion of the lens frame 30 and the rounded corner portion 34 is used as a contact portion with the cam member 6, friction can be reduced. Therefore, the drive source may have a low output, which is advantageous for further downsizing.

  Incidentally, FIG. 6 is a side view showing another example of the lens frame 30 and is configured to reduce friction at a contact portion with the cam member 6. That is, the roller 35 is provided on the outer edge portion of the lens frame 30, and the roller 35 is used as a contact portion with the cam member 6 so as to reduce friction.

  FIG. 7 is a side view showing another example of the cam member 6, and is an example in which the linkage configuration for linear drive is changed. That is, in the cam member 6, the rack gear 62 is extended to the main body 60, and the pinion gear 9 that meshes with the rack gear 62 is provided at the tip of the output shaft 29 of the stepping motor 7 so as to mesh them.

(A) is a top view which shows suitable one Embodiment of the lens unit based on this invention, (b) is the side view. It is a perspective view explaining the cam member shown in FIG. (A) is a top view which shows 2nd Embodiment of the lens unit based on this invention, (b) is the side view. It is a perspective view explaining the cam member shown in FIG. (A) is a top view which shows 3rd Embodiment of the lens unit based on this invention, (b) is the side view. It is a side view which shows the other example of a lens frame. It is a side view which shows the other example of a cam member.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image pick-up element 2 Lens 3 Lead screw 4 Lead nut 5 Guide pin 6 Cam member 7 Stepping motor 8 Spring member 9 Pinion gear 10 Base body 11 Drive part 12 Lens part 13 Recess 14 Guide rail 29 Output shaft 30 Lens frame 31 Guide part 32 Overhang portion 33 Through hole 34 Round corner portion 35 Roller 60 Main body 61 Linking piece 62 Rack gear 70 Storage case

Claims (9)

A lens unit that faces the imaging element on the base body side and supports the lens so as to be movable in the optical axis direction, and is moved by a driving means that performs linear driving,
Arranging at least one guide pin extending in the optical axis direction;
The lens frame with the lens mounted thereon is movably supported by linking the guide pin,
An inclined surface of a wedge-shaped cam member is disposed so as to be able to contact the lens frame,
Drive means for moving the cam member in a direction perpendicular to the optical axis is provided,
A lens unit configured to push and move the lens frame by linearly moving the cam member by the driving means.   The lens unit according to claim 1, further comprising an urging unit such as a spring that presses the lens frame toward the cam member.   The drive means uses a drive source as a motor to form a lead screw at the tip portion of the output shaft, and the cam member is provided with a lead nut that engages with the lead screw or a screw thread that becomes a lead nut, and the output shaft The lens unit according to claim 1 or 2, wherein the cam member is linearly moved in accordance with rotation of the lens unit.   The lens unit according to claim 3, wherein the motor is a flat stepping motor having stator coils on both sides of the rotor.   5. The lens unit according to claim 1, wherein a tip portion of the cam member is set to overlap with an outer edge portion of the lens frame in an initial state. A box-shaped case main body that houses the lens unit according to any one of claims 1 to 5, further comprising:
A lens unit, wherein the cam member is disposed so as to be inserted into a gap formed between the lens frame and the case body.   The lens unit according to claim 6, wherein a space is provided between the cam member and the case main body.   8. The lens unit according to claim 1, wherein the number of the guide pins is one and a mechanism for preventing rotation of the lens frame is provided. 9.   9. The lens unit according to claim 8, wherein one of the guide pins is disposed in the vicinity of a contact portion between the inclined surface of the cam member and the lens frame.

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