Patent Application
20070116445
The present invention relates to a lens drive device which is used in a relatively small camera such as a camera for a portable telephone with a camera or the like and a manufacturing method for the lens drive device.
In a portable telephone on which a camera is mounted, the portable telephone is often used such that the portable telephone is held by one hand to photograph user's own face or other object at a close position. Therefore, a photographing lens system used in this type of camera is frequently provided with a close-up photographing function. In the case of the photographing lens system provided with a close-up photographing function, the lens position at the time of performing normal photographing is different from the lens position at the time of performing close-up photographing, i.e., macro-photographing. In other words, the lens position at the time of close-up photographing is located at a position slightly nearer by a certain distance to an object to be photographed from a lens position at the time of normal photographing.
Therefore, in this type of the photographing lens system, a magnetic-drive mechanism for moving the lens between the normal photographing position and the macro photographing position is provided and the magnetic-drive mechanism is driven by the changeover of a switch to move the lens between the two photographing positions described above.
Conventionally, the focus of a photographing lens system is secured by merely improving the precision of components or, when the focus is to be adjusted, the adjustment is performed so as to set to focus on an imaging element by moving a lens-barrel to a lens position for the normal photographing, a lens position for the macro-photographing or both of the lens positions. Further, since the imaging element is often mounted by a user, focus is confirmed by using a CCD camera or the like before the imaging element is mounted.
However, a small camera, particularly the camera portion of a portable telephone is provided with an extremely small diameter of about 10 mm and its focal length is extremely short. Therefore, even when the precision of the components is secured, mounting errors are likely to occur to cause to have a problem of out of focus. Further, when focus adjustment is performed by moving the lens-barrel provided with a magnetic drive means in an optical axis direction, the positional relationship between the drive means provided in the lens-barrel and a drive means provided in a fixing body side is varied and thus thrust balance is varied. As a result, there is a problem that, when the lens-barrel is moved between the normal photographing position and the macro-photographing position, the operation of the lens-barrel becomes unstable and, depending on its stopped position, in the worst case, the lens-barrel is unable to be driven again. This operating malfunction is avoidable by increasing a thrust force of the drive means but the drive means is caused to be larger and thus it is not avoidable that the size of the lens drive device is increased. In addition, even when focus adjustment has been performed by using a CCD camera with a high degree of precision before an imaging element is mounted, since the imaging element is mounted after the focus adjustment, the focus of the lens with respect to the imaging element is shifted by the dimensional error of the imaging element or the mounting error of the imaging element, and thus a lens drive device with a stable quality cannot be obtained.
In view of the problems described above, it is an object of the present invention to provide a lens drive device with a stable quality which is capable of performing focus adjustment of a lens with respect to an imaging element while the positional relationship of a drive means is maintained.
In order to solve the problems described above, the present invention is characterized in that, in a lens drive device including a movable lens body provided with a lens, a drive means for moving the movable lens body in an optical axis direction of the lens, and a fixing body which movably supports the movable lens body in the optical axis direction, the movable lens body is comprised of a lens-barrel provided with a lens and a lens-barrel holder which movably supports the lens-barrel in the optical axis direction, the lens-barrel holder comprises a first magnetic means as the drive means, the fixing body comprises a second magnetic means as the drive means and a regulating part which regulates a moving range in the optical axis direction of the lens-barrel holder, and the movable lens body is moved by a magnetic attractive force or a magnetic repulsive force between the first magnetic means and the second magnetic means.
In the present invention, it is preferable that the lens-barrel holder is formed in a cylindrical shape and a female screw part is formed on its inner periphery, and a male screw part is formed on the outer periphery of the lens-barrel and the male screw part is threadedly engaged with the female screw part, and the lens-barrel is moved in the optical axis direction by relatively turning the lens-barrel holder with respect to the lens-barrel. According to the structure described above, the lens-barrel can be supported on the lens-barrel holder by the threaded engagement of screws. Therefore, adjustment work for focusing can be easily and surely performed and furthermore, after the adjustment, fixing work of the lens-barrel to the lens-barrel holder can be also easily and surely performed.
In order to manufacture a lens drive device in accordance with the present invention, it is preferable that the fixing body is structured as a case body inside of which the movable lens body is accommodated, the case body is structured to be capable of being divided into at least two portions such that respective portions are formed as half case bodies, the lens-barrel holder is abutted with an abutting part as the regulating part which is provided in one of the half case bodies, the one of the half case bodies and the other half case body are relatively moved in the optical axis direction such that a spacer is interposed between an abutting part as the regulating part provided in the other half case body and the lens-barrel holder, after that, the one of the half case bodies and the other half case body are fixed each other, and after that, the spacer is pulled out. According to the structure as described above, the stroke length of the lens-barrel holder corresponding to the thickness of the spacer can be formed. In other words, the stroke length of the lens-barrel holder with the regulating part of the fixing body can be easily and surely formed.
In order to manufacture a lens drive device in accordance with the present invention, it is preferable that the fixing body is structured as a case body inside of which the movable lens body is accommodated, the case body is structured to be capable of being divided into at least two portions such that respective portions are formed as half case bodies, abutting parts as the regulating parts which interpose the lens-barrel holder are provided on one of the half case bodies and the other half case body respectively, a gap space between the abutting parts is adjusted and the one of the half case bodies and the other half case body are fixed to each other, after that, an imaging element where an image transmitted through the lens is image-formed is fixed to the half case body, after that, the lens-barrel and the lens-barrel holder are relatively moved in the optical axis direction to adjust the focus of the lens to the imaging element. According to the structure as described above, even when the dimensional accuracy of the imaging element is not satisfactory or even when the focus of the lens to the imaging element shifts due to the mounting error of the imaging element or the like, since focus adjustment between the lens and the imaging element can be performed after the imaging element are mounted, a lens drive device with stable quality can be provided.
According to the present invention, since the movable lens body is structured of two components, i.e., the lens-barrel and the lens-barrel holder, focus adjustment can be performed by moving the lens-barrel in the optical axis direction with respect to the lens-barrel holder. Therefore, the position of the regulating part which regulates the moving range in the optical axis direction of the lens-barrel holder can be maintained, and the positional relationship between the first magnetic means provided in the lens-barrel holder as the drive means and the second magnetic means provided in the fixing body can be maintained. A method may be conceivable in which the position of the regulating part is varied to perform the focus adjustment. However, when the position of the regulating part is varied, the positional relationship of the drive means varies in accordance with the variation of the position of the regulating part. Therefore, designing in consideration of thrust force balance is required such that the variation of the positional relationship of the drive means can be permitted, and thus the size of the device is increased. According to the present invention, since the positional relationship between the first magnetic means and the second magnetic means is maintained, even when focus adjustment is performed, the thrust force balance between the first magnetic means and the second magnetic means does not vary. Therefore, designing in consideration of the unvaried thrust force balance, in other words, designing based on the minimum thrust force balance can be performed and the size of the lens drive device can be reduced. Further, interference due to focus adjustment between the first magnetic means and the second magnetic means can be avoided.
A lens drive device in accordance with an embodiment of the present invention will be described below with reference to the accompanying drawings. A manufacturing method for the lens drive device and a portable device with a camera will be described at the same time. Respective embodiments are structured suitable to be mounted as a camera portion of a portable device such as a portable telephone but may be mounted on other portable devices such as a PDA (Personal Digital Assistance).
As shown in
The movable lens body 10 includes a lens-barrel 10b provided with a lens 14 in the inside of a pipe body and a lens-barrel holder 10a which supports the lens-barrel 10b movably in the direction of the optical axis 11. The lens-barrel 10b is provided at one end with a bottomed part 10b1 having a circular incident window 18 for taking a reflected light from an object to be photographed to the lens 14 at a center portion. The bottomed part 10b1 is disposed on the upper side in
The lens-barrel holder 10a is formed in a cylindrical shape. The outer periphery of the upper portion in
A drive magnet 16, which is a first magnetic means and is formed in a ring shape, is fitted on the small diameter portion of the lens-barrel holder 10a. The drive magnet 16 is integrally fixed to the lens-barrel holder 10a in the state that the drive magnet 16 is abutted with the stepped portion. The drive magnet 16 is, as shown in
The case body 24 is structured of the first divided case body 26 and a second divided case body 42. In this embodiment, as shown in
The first divided case body 26 is formed in a tubular shape and an inner tubular part 26b is formed on the inner side in the radial direction of the outer tubular part 26a along a circumferential direction of the outer tubular part 26a. The outer tubular part 26a and the inner tubular part 26b are connected through a connecting part 26c and a U-shaped groove whose cross section is formed in a “U” shape is formed by the outer tubular part 26a, the inner tubular part 26b and the connecting part 26c. The upper end face of the inner tubular part 26b is an end face 27 as one of regulating parts (abutting part) with which the lower end face of the lens-barrel holder 10a abuts at a normal photographing position shown in
The second divided case body 42 is formed in a tubular shape that is provided with an aperture 42f at its upper part in
A first magnetic piece 32 and a second magnetic piece 34 formed in a ring shape are fixed on the respective bottoms of the U-shaped grooves which are formed in the first divided case body 26 and the second divided case body 42. The first drive coil 28 and the second drive coil 30 are fixed on the first magnetic piece 32 and the second magnetic piece 34 such that their inner walls are abutted with the inner tubular parts 26b, 42b and the first drive coil 28 and the second drive coil 30 are accommodated within the U-shaped grooves. Further, the first drive coil 28 and the second drive coil 30 face each other in the direction of the optical axis 11 and the first magnetic body 32 and the second magnetic body 34 are respectively disposed on the outer side in the direction of the optical axis 11 of the first and the second drive coils 28, 30.
The movable lens body 10 is housed in the case body 24 such that the upper and the under faces in the drawing of the drive magnet 16 which is provided on the lens-barrel holder 10a is located between the first drive coil 28 and the second drive coil 30. In other words, the drive magnet 16 is interposed in the direction of the optical axis 11 between the first and the second drive coils 28, 30. Therefore, the lens-barrel holder 10a slides on the sliding part 42e and moves in the direction of the optical axis 11 while the drive magnet 16 moves in the direction of the optical axis 11 by one or both of the first drive coil 28 and the second drive coil 30 that are energized. In this case, the lower end side of the lens-barrel holder 10a is not abutted with any portion so as to be allowed in a free condition.
The distance between the opposite faces of the first and the second drive coils 28, 30 is formed larger than the thickness of the drive magnet 16 in the direction of the optical axis 11 and thus a space in the direction of the optical axis 11 is formed between the drive magnet 16 and the first drive coil 28 or the second drive coil 30. Therefore, the drive magnet 16 is capable of moving in the range of the space and thus the lens-barrel holder 10a integrally formed with the drive magnet 16 is also capable of moving in the direction of the optical axis 11 in the range of the space.
On the other hand, at the normal photographing position shown in
Similarly as described above, also at the macro-photographing position where the lens-barrel holder 10a has been moved upward from the normal photographing position shown in
Next, a manufacturing method for the lens drive device 1 will be described with reference to
First, the first magnetic body 32 and the first drive coil 28 are successively disposed on the first divided case body 26. Pressure sensitive adhesive sheets 33 that serve as an adhesive are, as shown in
Similarly, the second magnetic body 34 and the second drive coil 30 are successively disposed to the second divided case body 42. Pressure sensitive adhesive sheets 35 are also stuck on the both sides of the second magnetic body 34. After that, the movable lens body 10, which is structured by the lens-barrel 10b threadedly engaged with the lens-barrel holder 10a in advance, is housed in the case body 24 such that the movable lens body 10 is interposed between the first and the second divided case bodies 26, 42.
Next, the moving range of the lens-barrel holder 10a housed in the case body 24 between the macro-photographing position and the normal photographing position, in other words, the stroke length of the lens-barrel holder 10a is adjusted.
A spacer 76 is used to adjust the gap “g1”. The spacer 76 is, as shown in
Before the first and the second divided case bodies 26, 42 are fitted to each other, the spacer 76 under the state that one piece of thread 77 is passed through the two through-holes 76b is disposed between the second divided case body 42 and the lens-barrel holder 10a as shown in
The case body portion in which the stroke length of the lens-barrel holder 10a is determined as described above is delivered to a camera maker or a portable device maker. An imaging element 44 and a circuit board 45 are fixed on the maker side to the case body portion which has been delivered. After that, the lens-barrel 10b and the lens-barrel holder 10a are relatively moved to adjust the focus of the lens to the imaging element 44. This adjustment is performed such that a jig is engaged with the engaging protrusion part 10b3 or the engaging groove 10b4 provided in the lens-barrel 10b to turn and move the lens-barrel 10b in the direction of the optical axis 11, and such that an image at the normal photographing position or the macro-photographing position is obtained, and such that the lens-barrel and the lens-barrel holder are fixed at a position where the image balance is satisfactory.
As described above, in the lens drive device 1 in accordance with this embodiment, the movable lens body 10 comprises the lens-barrel 10b provided with the lens 14 and a lens-barrel holder 10a which movably supports the lens-barrel 10b in the direction of the optical axis 11. Therefore, focus adjustment can be performed by moving the lens-barrel 10b in the optical axis direction. In other words, the positions of the end face 27 and the protruding edge 36 as the regulating parts for regulating the moving range in the direction of the optical axis 11 of the lens-barrel holder 10a can be maintained and the positional relationship between the drive magnet 16 and the first drive coil 28, the second drive coil 30 which are a drive means can be maintained in a constant state at the normal photographing position or the macro-photographing position. Therefore, even when focus adjustment is performed, the thrust force balance between the drive magnet 16 and the first drive coil 28 and the second drive coil 30 does not vary. As a result, designing in consideration of the unvaried thrust force balance, in other words, designing based on the minimum thrust force balance can be performed and the size of the lens drive device 1 can be reduced. Further, interference due to focus adjustment between the drive magnet 16 and the first drive coil 28 or the second drive coil 30 can be avoided.
Further, the female screw part 10a1 formed on the inner periphery of the lens-barrel holder 10a is threadedly engaged with the male screw part 10b1 formed on the outer periphery of the lens-barrel 10b, and the lens-barrel 10b can be moved in the direction of the optical axis 11 by relatively turning the lens-barrel holder 10a with respect to the lens-barrel 10b. Further, since the lens-barrel 10b can be supported by the lens-barrel holder 10a with threaded engagement of screws, adjustment work for focusing can be easily and surely performed and furthermore, after the adjustment, fixing work of the lens-barrel 10b to the lens-barrel holder 10a can be also easily and surely performed.
In addition, in the assembling of the lens drive device 1, the case body 24 for accommodating the movable lens body 10 is comprised of the first divided case body 26 and the second divided case body 42 each of which is a half case body. Further, the lens-barrel holder 10a is abutted with the end face 27 formed in the first divided case body 26 and, after the first divided case body 26 and the second divided case body 42 are relatively moved in the direction of the optical axis 11 such that the spacer 76 is sandwiched between the protruded part 36a of the protruding edge 36 formed in the second divided case body 42 and the lens-barrel holder 10a, the first divided case body 26 and the second divided case body 42 are fixed to each other and then the spacer 76 is pulled out. Therefore, the stroke length of the lens-barrel holder 9a corresponding to the thickness of the spacer 76 can be formed. Accordingly, the stroke length of the lens-barrel holder 10a with respect to the end face 27 of the first divided case body 26 and the protruding edge 36 of the second divided case body 42 can be easily and surely formed.
In addition, in the assembling of the lens drive device 1, the case body 24 accommodating the movable lens body 10 is comprised of the first divided case body 26 and the second divided case body 42 each of which is a half case body, and the first divided case body 26 and the second divided case body 42 are provided with the end face 27 and the protruding edge 36 that are the abutting parts respectively as the regulating part for interposing the lens-barrel holder 10a. Further, after the gap space between the abutting parts is adjusted and then the first divided case body 26 and the second divided case body 42 are fixed to each other, and the imaging element 44 to which an image transmitted through the lens 14 is formed is fixed to the first divided case body 26 via the circuit board 45 and, after that, the lens-barrel 10b and the lens-barrel holder 10a are relatively moved to adjust the focus of the lens 14 to the imaging element 44. Therefore, after the imaging element 44 has been mounted, focus adjustment between the lens 14 and the imaging element 44 can be performed. Accordingly, even when the dimensional accuracy of the imaging element 44 is not satisfactory or even when the focus of the lens 14 to the imaging element 44 shifts due to the mounting error of the imaging element 44, a lens drive device with stable quality can be provided without a problem.
In this embodiment, the outer wall on the upper end side of the lens-barrel holder 10a is abutted with the sliding part 42e as a guide portion which is formed on the second divided case body 42 and its lower end side is not abutted anywhere and is always allowed to be in a free condition. If a guide portion which guides the lower end side of the lens-barrel holder 10a is provided on the first divided case body 26, respective guide portions on the upper end side and the lower end side of the lens-barrel holder 10a are separately formed on different members. In this case, if the positional accuracy between the two guide portions is not secured, the operational malfunction of the lens-barrel holder 10a may occur. However, in this embodiment, since the lower end side of the lens-barrel holder 10a is allowed in a free state, the problem described above is prevented. Moreover, frictional resistance due to sliding does not occur on the lower end side and thus a load can be reduced and the size of the magnetic drive means 29 can be reduced. In addition, when the lens-barrel holder 10a moves to the normal photographing position (lower side) from the macro-photographing position (upper side), the tip end (lower end) in the moving direction of the lens-barrel holder 10a does not interfere with the inner wall of the inner tubular part 26b of the first divided case body 26 and thus operational malfunction does not occur.
Since only the upper end side of the lens-barrel holder 10a is guided, the lens-barrel holder 10a may have a possibility of inclination with respect to the direction of the optical axis 11 at an intermediate position between the normal photographing position and the macro-photographing position. However, in this embodiment, since photographing is not performed at the intermediate position, the inclination of the lens-barrel holder 10a does not cause a problem. Even when the lens-barrel holder 10a inclines at an intermediate position, when the lens-barrel holder 10a has moved to the normal photographing position, the bottom end face of the lens-barrel holder 10a abuts with the opposite end face 27 of the inner tubular part 26b and thus the inclination of the lens-barrel holder 10a can be corrected. Similarly, when the lens-barrel holder 10a has moved to the macro-photographing position, the upper end face of the lens-barrel holder 10a abuts with the opposite protruding edge 36 of the inner tubular part 42b and thus the inclination of the lens-barrel holder 10a can be corrected.
In this embodiment, the first and the second magnetic bodies 32, 34 are respectively disposed on the outer side in the direction of the optical axis 11 of the first drive coil 28 and the second drive coil 30 so as to have a function as a back yoke and, in addition, have a function to hold the position of the lens-barrel holder 10a together with the drive magnet 16. In other words, at the normal photographing position shown in
The embodiment described above is a preferred example of the present invention but many modifications can be made without departing from the present invention. For example, in the embodiment shown in
Further, in order to lightly press-fit the inner wall of the lens-barrel holder 10a with the outer wall of the lens-barrel 10b, their dimensional accuracies are required to be managed considerably strictly. Therefore, the inner wall of the lens-barrel holder 10a and the outer wall of the lens-barrel 10b may be structured in a loosely engaged state and an urging member having a spring property is protruded from one of them so as to abut with the other and thus the inner wall of the lens-barrel holder 10a and the outer wall of the lens-barrel 10b are abutted with each other in an urging state.
As a focus adjustment method in the case that the inner wall of the lens-barrel holder 10a and the outer wall of the lens-barrel 10b are lightly press-fitted to each other, for example, a following method may be utilized. In other words, through holes are respectively formed in the walls where the lens-barrel holder 10a and the lens-barrel 10b are radially overlapped with each other. An adjusting rod is inserted into both the through holes from the outside so as to engage with them simultaneously and focus adjustment can be performed by moving the adjusting rod in an upper and a lower directions.
Further, another adjustment method may be used. In other words, a circular hole is formed in the wall of the lens-barrel holder 10a which is radially overlapped with the lens-barrel 10b, and an elongated hole which is extended in a direction perpendicular to the optical axis 11 (circumferential direction of the outer peripheral face) is formed in the wall of the lens-barrel 10b which is radially overlapped with the lens-barrel holder 10a. The tip end of an eccentric pin is inserted through the circular hole from the outside and is engaged with the elongated hole and the eccentric pin is turned. In this manner, the lens-barrel 10b is moved in the direction of the optical axis 11 to adjust the focus.
In addition, as shown in
In addition, as shown in
In addition, in this embodiment, after the lens-barrel 10b is threadedly engaged with the lens-barrel holder 10a in advance, they are accommodated within the case body 24. However, at first, only the lens-barrel holder 10a may be accommodated in the case body 24 and, after that, the lens-barrel 10b is threadedly engaged with the lens-barrel holder 10a. In this case, it is preferable that a plurality of grooves is formed in the circumferential direction on the tip end of the entrance 10b2 of the lens-barrel 10b and the lens-barrel 10b is turned by a turning jig which is engaged with these grooves.
In addition, the imaging element 44 in this embodiment is comprised of a CMOS (Complementary Metal Oxide Semiconductor) but a CCD, a VMIS or the like may be utilized other than a CMOS. Further, the lens drive device 1 is incorporated as a mechanism for a camera portion in a cellular telephone with a camera. However, the lens drive device 1 may be used in other portable devices such as a mobile computer and a PDA or other camera devices such as a monitor camera and a camera for medical application, or may be incorporated into an electronic device for a car, a television or the like.
The present invention may be applied to a camera device. Further, the present invention may be applied to a portable device such as a cellular telephone provided with a camera function. In addition, the present invention can be incorporated into all electronic equipments when the electronic equipment is provided with a position changing mechanism for a lens.
While this invention has been described in conjunction with the specific embodiments outlined above, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, the preferred embodiments of the invention as set forth above are intended to be illustrative, not limiting. Various changes may be made without departing from the spirit and scope of the invention as defined in the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2003-407634 | Dec 2003 | JP | national |
This application claims priority of International Application No. PCT/JP2004/011962, filed Aug. 20, 2004, and Japanese Application No. 2003-407634, filed Dec. 5, 2003, the complete disclosures of which are hereby incorporated by reference.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP04/11962 | 8/20/2004 | WO | 6/5/2006 |
