Patent Publication Number: US-2007116445-A1

Title: Lens drive device and manufacturing method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
      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. 
    
    
     FIELD OF THE INVENTION  
      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.  
     BACKGROUND OF THE INVENTION  
      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&#39;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.  
     SUMMARY OF THE INVENTION  
      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). 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a sectional view showing a lens drive device in accordance with the present invention;  
       FIG. 2  is an exploded perspective view showing the lens drive device shown in  FIG. 1 ;  
       FIG. 3  is an exploded cross-sectional view showing the lens drive device shown in  FIG. 1 ;  
       FIG. 4  is a sectional view showing an essential portion of the lens drive device shown in  FIG. 1 ;  
       FIG. 5  is a sectional view of a second divided case body portion which shows a state where a spacer is set in the lens drive device shown in  FIG. 1 ;  
       FIG. 6  is a plan view showing a spacer which is used when the lens drive device in  FIG. 1  is manufactured; and  
       FIG. 7  is a plan view showing a magnet which is used in the lens drive device in  FIG. 1 .  
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a sectional view showing a lens drive device in accordance with the present invention.  FIG. 2  is an exploded perspective view showing the lens drive device shown in  FIG. 1 .  
      As shown in  FIG. 1  or  FIG. 2 , the lens drive device  1  mainly includes a movable lens body  10  which holds a lens  14  of a camera for photographing, a magnetic drive means  29  for linearly moving the movable lens body  10  along the direction of an optical axis  11  of the lens  14 , a case body  24  which is a fixing body for accommodating the movable lens body  10  and the magnetic drive means  29 , an imaging element  44  where an image passing through the lens  14  is formed, and a circuit board  45  on which the imaging element  44  is fixed. In this embodiment, the imaging element  44  is comprised of a CMOS (Complementary Metal Oxide Semiconductor).  
      The movable lens body  10  includes a lens-barrel  10   b  provided with a lens  14  in the inside of a pipe body and a lens-barrel holder  10   a  which supports the lens-barrel  10   b  movably in the direction of the optical axis  11 . The lens-barrel  10   b  is provided at one end with a bottomed part  10   b   1  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  10   b   1  is disposed on the upper side in  FIG. 1 . An engaging protrusion part  10   b   3  and an engaging groove  10   b   4 , which are formed for turning the lens-barrel  10   b  by using a specified jig, are formed on the upper face in the drawing of the bottomed part  10   b   1  in the direction of the optical axis  11  in a protruded or recessed manner. Further, the upper part in  FIG. 1  of the lens-barrel  10   b  is formed in a small diameter portion and the lower part is formed in a large diameter portion whose diameter is larger than the small diameter portion. A male screw part  10   b   5  is formed on the outer wall of the small diameter portion (see  FIG. 2 ). The lens  14  is disposed in the order of an object side lens  14   a , an intermediate lens  14   b  and a camera body side lens  14   c  from the bottomed part  10   b   1  side of the lens-barrel  10   b . A position fixing member  14   f  is fixed to the entrance  10   b   2  of the lens-barrel  10   b  so as to hold three pieces of lens  14 . The clearance between the object side lens  14   a  and the intermediate lens  14   b  are held to be in a constant state by a spacer  14   d , which serves as a diaphragm, and the clearance between the intermediate lens  14   b  and the camera body side lens  14   c  is held to be in a constant state by a spacer  14   e.    
      The lens-barrel holder  10   a  is formed in a cylindrical shape. The outer periphery of the upper portion in  FIG. 1  is formed in a small diameter portion and the outer periphery of the lower portion is formed in a large diameter portion whose diameter is larger than that of the small diameter portion and a stepped portion is formed at the boundary of the small diameter portion and the large diameter portion. A female screw part  10   a   1  is formed on the inner wall of the lens-barrel holder  10   a  (see  FIG. 2 ). The female screw part  10   a   1  is threadedly engaged with the male screw part  10   b   5 . In other words, the lens-barrel  10   b  is rotatably engaged in and with the lens-barrel holder  10   a  and, by rotating the lens-barrel  10   b , the lens-barrel  10   b  can be moved to the lens-barrel holder  10   a  in the direction of the optical axis  11 . The lens-barrel holder  10   a  is formed with a rotation preventing part not shown in the drawing which is protruded from its upper face. The rotation preventing part is engaged with a rotation preventing groove  42   d  which is formed on a second divided case body  42 . Therefore, turning of the lens-barrel holder  10   a  together with the lens-barrel  10   b  is prevented when the lens-barrel  10   b  is turned, and thus the lens-barrel  10   b  can be efficiently moved.  
      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  10   a . The drive magnet  16  is integrally fixed to the lens-barrel holder  10   a  in the state that the drive magnet  16  is abutted with the stepped portion. The drive magnet  16  is, as shown in  FIG. 7 , magnetized into a single pole such that the portion surrounding a center hole is magnetized in an N-pole and the entire outer peripheral portion is magnetized in an S-pole respectively. Alternatively, the magnetized relationship of NS may be reversed.  
      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  FIG. 1 , the first divided case body  26  is disposed on the lower side and the second divided case body  42  is disposed on the upper side. The first divided case body  26  and the second divided case body  42  are integrated with each other by means of that cylindrical protruded portions, which are protruded in the direction of the optical axis  11  from respective outer tubular parts  26   a ,  42   a , are engaged with each other radially. A pair of drive coils  28 ,  30 , which are a second magnetic means and formed in a ring shape, are respectively fixed to the first and the second divided case bodies  26 ,  42 . Further, a circuit board  45  is fixed on the under face of the first divided case body  26 .  
      The first divided case body  26  is formed in a tubular shape and an inner tubular part  26   b  is formed on the inner side in the radial direction of the outer tubular part  26   a  along a circumferential direction of the outer tubular part  26   a . The outer tubular part  26   a  and the inner tubular part  26   b  are connected through a connecting part  26   c  and a U-shaped groove whose cross section is formed in a “U” shape is formed by the outer tubular part  26   a , the inner tubular part  26   b  and the connecting part  26   c . The upper end face of the inner tubular part  26   b  is an end face  27  as one of regulating parts (abutting part) with which the lower end face of the lens-barrel holder  10   a  abuts at a normal photographing position shown in  FIG. 1 .  
      The second divided case body  42  is formed in a tubular shape that is provided with an aperture  42   f  at its upper part in  FIG. 1 . Further, the second divided case body  42  is provided with an inner tubular part  42   b  that is extended along a circumferential direction of the outer tubular part  42   a  on the inner side in the radial direction of the outer tubular part  42   a . The outer tubular part  42   a  and the inner tubular part  42   b  are connected through a connecting part  42   c  and a U-shaped groove is formed by the outer tubular part  42   a , the inner tubular part  42   b  and the connecting part  42   c . A protruding edge  36 , which is the other of the regulating parts (abutting part) with which the upper end face of the lens-barrel holder  10   a  abuts at a macro-photographing position where the lens-barrel holder  10   a  moves upward from the normal photographing position shown in  FIG. 1 , is formed on the inner tubular part  42   b . The protruding edge  36  is formed with a turning prevention groove  42   d  (see  FIG. 2 ) which is to be engaged with the rotation preventing part that is protruded from the upper face of the lens-barrel holder  10   a . Further, the protruding edge  36  is provided with a protruded part  36   a  which protrudes downward in the direction of the optical axis  11 . The inner wall side of the inner tubular part  42   b  is formed to be a sliding part  42   e  which abuts with the outer wall on the upper end side of the lens-barrel holder  10   a  as a guide portion when the lens-barrel holder  10   a  moves in the direction of the optical axis  11 .  
      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  26   b ,  42   b  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  10   a  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  10   a  slides on the sliding part  42   e  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  10   a  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  10   a  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  FIG. 1 , the bottom end face of the lens-barrel holder  10   a  abuts with the end face  27  of the inner tubular part  26   b . Therefore, it is structured such that a little clearance is formed between the first drive coil  28  and drive magnet  16 , and thus a collision between the first drive coil  28  and the drive magnet  16  is prevented. Therefore, the damage of the first drive coil  28  or the drive magnet  16  can be prevented.  
      Similarly as described above, also at the macro-photographing position where the lens-barrel holder  10   a  has been moved upward from the normal photographing position shown in  FIG. 1 , it is structured such that the upper end face of the lens-barrel holder  10   a  abuts with the protruding edge  36  and thus a little clearance is formed between the second drive coil  30  and the drive magnet  16  and a collision between the second drive coil  30  and the drive magnet  16  is prevented. Therefore, the damage of the second drive coil  30  or the drive magnet  16  can be prevented. The turning prevention groove  42   d  always engages with the turning preventing part which is protruded from the upper face of the lens-barrel holder  10   a  even when the lens-barrel holder  10   a  moves between the normal photographing position and the macro-photographing position.  
      Next, a manufacturing method for the lens drive device  1  will be described with reference to  FIGS. 3 through 6 .  FIG. 3  is an exploded sectional view showing the lens drive device shown in  FIG. 1 .  FIG. 4  is a sectional view showing an essential portion of the lens drive device shown in  FIG. 1 .  FIG. 5  is a sectional view showing a second divided case body to which a spacer is fitted in the lens drive device shown in  FIG. 1 .  FIG. 6  is a plan view showing a spacer that is used when the lens drive device in  FIG. 1  is manufactured.  
      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  FIG. 3 , stuck on the both sides of the first magnetic body  32 .  
      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  10   b  threadedly engaged with the lens-barrel holder  10   a  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  10   a  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  10   a  is adjusted.  FIG. 4  is a cross sectional view showing an essential portion in the state that the lens-barrel holder  10   a  is abutted with the end face  27  of the first divided case body  26  as the lower moving limit. The gap “g 1 ” which is the largest gap length between the protruded part  36   a  provided on the protruding edge  36  that is the upper abutting part and the lens-barrel holder  10   a  corresponds to the stroke length of the lens-barrel holder  10   a.    
      A spacer  76  is used to adjust the gap “g 1 ”. The spacer  76  is, as shown in  FIGS. 5 and 6 , formed in a flat plate shape and provided with a plurality of protruded parts  76   a  on its outer periphery and two through-holes  76   b  at its center portion. When the gap “g 1 ” is adjusted, a thread  77  is passed through the two through-holes  76   b  of the spacer  76 .  
      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  76   b  is disposed between the second divided case body  42  and the lens-barrel holder  10   a  as shown in  FIG. 5 . Both ends of one piece of the thread  77  are drawn out outside from the aperture  42   f  of the second divided case body  42 . In this state, the first and the second divided case bodies  26 ,  42  are temporarily fixed. Then, the first divided case body  26  and the second divided case body  42  are moved close to each other in the direction of the optical axis  11  such that the spacer  76  is firmly sandwiched by the protruded part  36   a  and the lens-barrel holder  10   a . When the spacer  76  is firmly sandwiched by the first and the second divided case bodies  26 ,  42 , they are completely integrated with each other with an adhesive or welding. After that, the spacer  76  is pulled out through the aperture  42   f  by holding and pulling both the ends of the thread  77 . As a result, the gap “g 1 ” that is the largest gap length becomes to be the same as the thickness of the spacer  76 .  
      The case body portion in which the stroke length of the lens-barrel holder  10   a  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  10   b  and the lens-barrel holder  10   a  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  10   b   3  or the engaging groove  10   b   4  provided in the lens-barrel  10   b  to turn and move the lens-barrel  10   b  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  10   b  provided with the lens  14  and a lens-barrel holder  10   a  which movably supports the lens-barrel  10   b  in the direction of the optical axis  11 . Therefore, focus adjustment can be performed by moving the lens-barrel  10   b  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  10   a  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  10   a   1  formed on the inner periphery of the lens-barrel holder  10   a  is threadedly engaged with the male screw part  10   b   1  formed on the outer periphery of the lens-barrel  10   b , and the lens-barrel  10   b  can be moved in the direction of the optical axis  11  by relatively turning the lens-barrel holder  10   a  with respect to the lens-barrel  10   b . Further, since the lens-barrel  10   b  can be supported by the lens-barrel holder  10   a  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  10   b  to the lens-barrel holder  10   a  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  10   a  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  36   a  of the protruding edge  36  formed in the second divided case body  42  and the lens-barrel holder  10   a , 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  9   a  corresponding to the thickness of the spacer  76  can be formed. Accordingly, the stroke length of the lens-barrel holder  10   a  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  10   a . 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  10   b  and the lens-barrel holder  10   a  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  10   a  is abutted with the sliding part  42   e  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  10   a  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  10   a  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  10   a  may occur. However, in this embodiment, since the lower end side of the lens-barrel holder  10   a  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  10   a  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  10   a  does not interfere with the inner wall of the inner tubular part  26   b  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  10   a  is guided, the lens-barrel holder  10   a  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  10   a  does not cause a problem. Even when the lens-barrel holder  10   a  inclines at an intermediate position, when the lens-barrel holder  10   a  has moved to the normal photographing position, the bottom end face of the lens-barrel holder  10   a  abuts with the opposite end face  27  of the inner tubular part  26   b  and thus the inclination of the lens-barrel holder  10   a  can be corrected. Similarly, when the lens-barrel holder  10   a  has moved to the macro-photographing position, the upper end face of the lens-barrel holder  10   a  abuts with the opposite protruding edge  36  of the inner tubular part  42   b  and thus the inclination of the lens-barrel holder  10   a  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  10   a  together with the drive magnet  16 . In other words, at the normal photographing position shown in  FIG. 1 , even when an electric current is not applied to the drive coils  28  and  30 , the position of the lens-barrel holder  10   a  can be held by a magnetic attractive force generated between the drive magnet  16  and the first magnetic body  32 . Similarly, at the macro-photographing position where the lens-barrel holder  10   a  has moved upwards from the normal photographing position, even when an electric current is not applied to the drive coils  28  and  30 , the position of the lens-barrel holder  10   a  can be held by a magnetic attractive force generated between the drive magnet  16  and the first magnetic body  32 .  
      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  FIG. 2 , the female screw part  10   a   1  is formed on the inner wall of the lens-barrel holder  10   a  and the male screw part  10   b   1  is formed on the outer wall of the lens-barrel  10   b , and the female screw part  10   a   1  and the male screw part  10   b   1  are threadedly engaged with each other. However, threaded engagement is not always required and engagement with a cam may be used when the lens-barrel holder  10   a  is capable of movably supporting the lens-barrel  10   b  in the direction of the optical axis  11 . Alternatively, simple light press-fitting may be utilized. In the case of the light press-fitting, a serration mechanism may be used to prevent turning around the optical axis  11  of the lens  14 .  
      Further, in order to lightly press-fit the inner wall of the lens-barrel holder  10   a  with the outer wall of the lens-barrel  10   b , their dimensional accuracies are required to be managed considerably strictly. Therefore, the inner wall of the lens-barrel holder  10   a  and the outer wall of the lens-barrel  10   b  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  10   a  and the outer wall of the lens-barrel  10   b  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  10   a  and the outer wall of the lens-barrel  10   b  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  10   a  and the lens-barrel  10   b  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  10   a  which is radially overlapped with the lens-barrel  10   b , 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  10   b  which is radially overlapped with the lens-barrel holder  10   a . 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  10   b  is moved in the direction of the optical axis  11  to adjust the focus.  
      In addition, as shown in  FIG. 1 , in this embodiment, the rotation preventing part for preventing co-rotation of the lens-barrel holder  10   a  with the lens-barrel  10   b  is formed on the lens-barrel holder  10   a  side. However, the rotation preventing part may be formed on the lens-barrel  10   b  side. In other words, any structure which can prevent the co-rotation of the lens-barrel holder  10   a  with the lens-barrel  10   b  may be utilized. Therefore, the turning prevention groove  42   d  formed on the protruding edge  36  which engages with the rotation preventing part not shown in the drawing is not always required to be formed on the protruding edge  36  and may be formed on the first divided case body  26  side.  
      In addition, as shown in  FIG. 1 , while the upper end side of the lens-barrel holder  10   a  is guided by the sliding part  42   e  which is formed on the inner wall side of the inner tubular part  42   b , its lower end side moves in the direction of the optical axis  11  in a free state without being guided. However, a sliding part may be formed on the inner wall side of the inner tubular part  26   b  of the first divided case body  26  such that the lens-barrel holder  10   a  moves in the direction of the optical axis  11  while the upper and lower ends of the lens-barrel holder  10   a  are simultaneously guided.  
      In addition, in this embodiment, after the lens-barrel  10   b  is threadedly engaged with the lens-barrel holder  10   a  in advance, they are accommodated within the case body  24 . However, at first, only the lens-barrel holder  10   a  may be accommodated in the case body  24  and, after that, the lens-barrel  10   b  is threadedly engaged with the lens-barrel holder  10   a . In this case, it is preferable that a plurality of grooves is formed in the circumferential direction on the tip end of the entrance  10   b   2  of the lens-barrel  10   b  and the lens-barrel  10   b  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.