Patent Application
20060109565
The present invention is related to a lens drive apparatus which makes lenses movable to carry out optical zoom and focusing, and to a lens drive apparatus which can move lenses to carry out the operations of optical zoom, macro and focus, and in particular to an improvement of drive operations in a simplified lens structure which can be applied to ultraminiature cameras.
In recent years, portable telephones equipped with ultraminiature cameras have become widespread. Such ultraminiature cameras generally use a fixed focal point due to size restrictions. The presence or absence of such ultraminiature cameras holds a big weight in the selection of phone types when a portable telephone is purchased. Further, whether or not a portable telephone is equipped with an ultraminiature camera is a big point in the mind of a user, but in actuality not very much concern is given to the performance and function of the ultraminiature camera.
However, as portable telephones equipped with existing fixed focal point type ultraminiature cameras have become widespread, the user who has been using such portable telephones after a normal period of use will naturally want higher functions in order to be distinguished from other people and the like. One example of a higher function is an optical zoom function used in a still camera or a video camera or the like.
In such optical zoom function, a desired zoom is obtained and focusing is carried out in accordance with that zoom normally by appropriately moving two or more lens groups in the optical axis direction. Further, as a specific structure for carrying out such process, as shown in Japanese Laid-Open Patent Application No. HEI 7-336938 (Patent Document 1), for example, two lenses are respectively moved by independent actuators (stepping motors). Further, as another method, as shown in Japanese Laid-Open Patent Application No. HEI 11-52209(Patent Document 2), by using a cam for one actuator or motor, the positional relationship of two lenses (lens groups) is controlled, and this achieves the two operations of zoom and focus.
The movement of the lenses for achieving optical zoom is complex, and instead of just movement in one direction, a non-linear curve that includes a round trip is drawn. In particular, in order to be installed in a portable telephone, the optically effective lens diameter (hereafter “lens diameter”) needs to be less than or equal to φ 7 mm, and should preferably be less than or equal to φ 5 mm, and in the case where an ultraminiature lens is used in that way, the position accuracy of the lenses becomes strict, and this requires highly accurate positioning and a high level of control.
For this reason, in addition to a drive circuit for operating an actuator, there is a need for a circuit which processes data from images and sensors for measuring the distance to objects and confirming positions and the like, and supplies feedback to the drive circuit. In other words, this requires highly accurate sensors and data processing, portions requiring control, development, and design man-hours. Furthermore, there is a high cost accompanying an increase in the number of components, the power consumption becomes larger, and the size becomes large scale, whereby it becomes difficult to install in portable telephones and the like. In particular, as described in Patent Document 1, in the case where a drive system is provided for each lens, the problems described above become more pronounced.
On the other hand, in the case where a cam is used as in the invention disclosed in Patent Document 2, this is feasible with one actuator, but a cam and a guide having a plurality of different curvatures are required in order to carry out nonlinear movement. For this reason, the movement and the mechanical mechanism are also complex. Furthermore, because the movement of the lenses is very different from the camera method, the cam must be developed and designed to such extent.
Further, as shown in Japanese Laid-Open Patent Application No. 2002-290523 (Patent Document 3), a drive apparatus equipped with a zoom function for installation in a portable telephone achieves zoom by using a cam for one actuator (motor) to control the positional relationship of two longitudinal lenses (group lenses). However, the invention disclosed in the publication described above is a double cylinder cam mechanism in which a fixed cylinder for a slot of a linear guide is arranged around the lenses, and a cam cylinder which transmits a driving force is arranged on the outside thereof, and because these are housed in a cylindrical housing, there is the problem of the external size becoming big.
Further, in order to achieve macro operations, a desired macro-focus is obtained by appropriately moving the two longitudinal group lenses in the optical axis direction, and in this case because the relative positional relationship of the longitudinal group lenses and the image taking element is different from the zoom function, in order to make these compatible, each group lens needs to be moved independently. However, when a structure is formed in which each group lens is independently moved by two actuators, the body becomes large, and this makes it difficult to carry out ultraminiaturization. Further, when zoom and macro operations are obtained using a cam mechanism, the structure thereof becomes complex, and this makes it difficult to carry out ultraminiaturization.
In view of the background described above, it is an object of the present invention to solve the problems described above without the need for a complex cam mechanism or highly accurate control or complex mechanisms, and provide a simple miniature lens drive apparatus at low cost by limiting the zoom magnification. Further, it is another object to provide a lens drive apparatus having an ultraminiature external size which makes it possible to carry out the operations of optical zoom, macro and focus by one actuator in order to be preferably installed in portable telephones and the like to achieve thinner and smaller scale devices.
In order to achieve the objects stated above, the lens drive apparatus according to the present invention is a lens drive apparatus for moving lenses in a lens unit having an optical zoom function for use in an ultraminiature camera which uses lenses having a lens diameter of 7 mm or less, and is equipped with first and second lens support members arranged in the front and back, wherein each of said first and second lens members holds a prescribed number of lenses. Further, in such proposed structure, said first lens support member is fixed, and said second lens support member is made movable in the forward and backward directions and is constructed so as to stop at two prescribed positions in the forward and backward directions, and this makes it possible to switch between two kinds of zoom magnification.
Further, as another solution means, in the proposed structure described above, said first lens support member is made movable in the forward and backward directions and is constructed so as to stop at two prescribed positions in the forward and backward directions, and said second lens support member is made movable in the forward and backward directions and is constructed so as to stop at two prescribed positions in the forward and backward directions, and this makes it possible to switch between two kinds of zoom magnification by controlling the stopping positions of said first and second lens support members.
In this case, preferably at least one solenoid, relay or permanent magnet is used as an actuator to move said first lens support member and said second lens support member, and this makes it possible to control the switching of the two kinds of relative positional relationship by moving the first and second lens support members in accordance with the output of the actuator. When this structure is formed, the switching control can be achieved by a simpler structure.
Further, as another solution means, in the proposed structure described above, said first lens support member is made movable in the forward and backward directions and is constructed so as to stop at two prescribed positions in the forward and backward directions, and said second lens support member is made movable in the forward and backward directions and is constructed so as to stop at three prescribed positions in the forward and backward directions, and this makes it possible to switch between three kinds of zoom magnification by controlling the stopping positions of said first and second lens support members.
In this case, when said second lens support member receives the output of a stepping motor to move forward and backward, and said first lens support member is made movable by a biasing force from said second lens support member and is stopped at the two positions of a first position in the state when said biasing force is not received, and a second position when being moved by said biasing force, it is possible to switch between three kinds of zoom magnification by one actuator and a simple power transmission mechanism. This invention is achieved by the thirteenth embodiment, for example.
Furthermore, in each of the inventions described above, the movement of at least one of said first lens support member and said second lens support member can be carried out based on the output of a stepping motor.
In this regard, in the embodiments, the first lens support member corresponds to the member (front group support body 40, front group movable body 3, 40′, front lens support body 53, front lens group 61, 71 and the like) which supports the front lens group, and the second lens support member corresponds to the member (rear group movable body 4, 30, rear lens support body 54, rear lens group 62, 72 and the like) which supports the rear lens group, but the present invention is not limited to this, and depending on the operational characteristics which show the relative relationship between the zoom magnification and the lens position, the reverse application may also be obtained.
In the present invention, the stopping positions were limited to 2 or 3 positions. In this way, positioning can be carried out easily using a simple miniature structure, and by properly setting the stopping positions in accordance with the operational characteristics, it is possible to exhibit different zoom magnifications.
Further, because the number of stopping positions is limited in this way, even in the case where a plurality of stepping motors are used as actuators, for example, because the positioning of each lens support member can be carried out by abutment positioning, it is possible to carry out highly accurate positioning by simple control. Accordingly, the size of the apparatus does not become larger. Further, these merits may be obtained by driving one side with a stepping motor, by attracting/repelling one side with a relay, a solenoid or a permanent magnet, or by manual operation driving.
Further, using one of any of these as an actuator, by appropriately transmitting the output thereof to each of the lens support members, it is possible to obtain different relative positional relationships, and this makes it possible to change the zoom magnification.
Furthermore, even when the first lens support member is fixed, because it is possible to obtain two kinds of zoom magnification by appropriately setting the stopping positions of the second lens support member, the present invention can be achieved by an extremely simple miniature mechanism.
Further, the applied lens diameter is made 7 mm or less for the reason given below. Namely, in ultraminiature cameras used in portable telephones and the like, the surface area of the camera module forms a size less than or equal to 13 mm square even for fixed focusing, and this level is used as an upper limit. In this regard, in order to fix the lens, a fixed frame of at least about 1 mm needs to be provided, and the size of the lens module becomes “lens diameter+2 mm”. Further, because an actuator and a slide mechanism are provided on the outside of such lens module, in order to make the total size 13 mm or less, the lens diameter needs to be made less than or equal to φ 7 mm. Of course, when considering a certain degree of margin and further miniaturization of the devices into which the camera will be mounted such as portable telephones and the like, φ 7 mm is the upper limit, and the diameter is preferably less than or equal to φ 5 mm. Of course, the application object of the lens drive apparatus of the present invention is not limited to portable telephones.
In order to achieve the other objects described above, the lens drive apparatus according to the present invention is a lens drive apparatus for moving lenses in a lens unit having an optical zoom function for use in an ultraminiature camera which uses lenses having a lens diameter of 7 mm or less, and is equipped with first and second lens support members arranged in the front and back, wherein each of said first and second lens members holds a prescribed number of lenses. Further, said first lens support member is fixed, and said second lens support member is made movable in the forward and backward directions, is constructed so as to stop at two fixed positions in the forward and backward directions, and is driven to move a minute distance at said fixed positions, whereby it is possible to carry out operations which change optical zoom and focus.
In this regard, in the embodiments, the first lens support member corresponds to the member (frame 3, front group support body 40) which supports the front lens group, and the second lens support member corresponds to the member (frame 4, rear group movable body 30) which supports the rear lens group, but the present invention is not limited to this, and depending on the operational characteristics which show the relative relationship between the zoom magnification and the lens position, the reverse application may also be obtained.
In the present invention, the stopping positions were limited to 2 fixed positions, wherein such fixed positions form base positions where minute distance movement is carried out. In this way, positioning can be carried out easily using a simple miniature structure, and by properly setting the stopping positions in accordance with the operational characteristics, it is possible to exhibit different zoom magnifications. For this reason, a zoom operation having two values is carried out even in a structure where only the one second lens support member is driven.
Further, because the rear lens is moved minutely at each fixed position, focusing is possible, and this makes it possible to carry out a focus operation. Further, from the fact that there is movement over a minute distance, the zoom focal point is moved out of place soon, and focusing takes place at a focal point existing at a very close position, whereby macro operations are carried out.
Further, as confirmed by experiment, if the minute movement at said fixed positions carries out movement by a feed pitch less than or equal to 50 μm for at least a 500 μm section front and back, it is possible to easily use the macro focal point existing at a very close position. Further, when the feed pitch of said minute movement is made less than or equal to several μm, the focus operation becomes easy.
Further, a stepping motor is used as a drive source in said drive means, a lead screw is provided on the output shaft of the stepping motor, a lead nut is provided at a corresponding position of said second lens support member, and a linear operation is carried out by connecting the lead screw and the lead nut. In this case, from the fact that a stepping motor is used, driving can be carried out over an open loop, the structure becomes simple without the need for a position detection sensor or the like, and the drive control becomes easy.
Further, said stepping motor is a flat type in which steps are arranged on the left and right of the rotor. In this case, because the drive source becomes flat, the thickness of the lens drive apparatus can be greatly reduced, and this is advantageous in view of ultraminiaturization.
The foregoing and other objects, features and advantages of the invention will become more readily apparent from the following detailed description of a preferred embodiment of the invention that proceeds with reference to the accompanying drawings.
The present invention will be described in greater detail with reference to the appended drawings.
Further, in order to construct an ultraminiature camera, an image taking element 6 such as a CCD or the like is arranged at a prescribed rear position of the cylindrical body 5. In this way, by appropriately setting the distance to each of the lens groups 1, 2 and the image taking element 6 such as a CCD or the like and the distance between both lens groups 1, 2, it is possible to form an image at a prescribed zoom magnification. Of course, the output of the image taking element 6 such as a CCD or the like is inputted into a prescribed image processing apparatus, but because the body structure of the ultraminiature camera has no relationship with the present invention, a description thereof is omitted. Further,
In the description given below, the relationship of the positions of the two lens groups 1, 2 and the zoom magnification (in focus) is like that shown in
Further, from the state of the base 1× shown in
In this regard, in the present invention, it was observed that the movement path of the front lens group 1 for a zoom magnification from 1× to γ× moves forward after first moving backward temporarily. Namely, when viewing the position of the front lens group 1, if A forms the position at the time when the zoom magnification is the base 1×, then the position is the same A when the zoom magnification is β×. Accordingly, if the front lens group 1 is fixed (the front group movable body 3 is made a simple holding member), and the rear lens group 2 is made to move freely in a round trip stopping at the two positions (FIGS. 1(a), (c)) of the base position (1) and the position (3), it is possible to achieve a lens drive apparatus in which the zoom magnification has the two kinds of magnification 1× and β×. The operation characteristics (zoom magnification and lens position relationship) in this case are shown in
Further, such structure is achieved by one drive mechanism for the rear lens group 2. Furthermore, because there is a round trip movement between the two positions (1), (2), a miniature drive mechanism can be achieved easily by a stepping motor of course, or by a solenoid, a relay, a magnet or the like, and this makes it possible to carry out further miniaturization.
Further, when the front lens group 1 and the rear lens group 2 are each made independently movable in a round trip between two prescribed positions, it is possible to achieve a lens drive apparatus for an ultraminiature camera which obtains a plurality of zoom magnifications as described below.
Namely, the front lens group 1 is moved in a round trip to stop at the two positions of the base position A and the rear position B, and the rear lens group 2 is moved in a round trip to stop at the base position (1) and the front position (2). In this way, by carrying out control like the operation characteristics shown in
In the same way, the front lens group 1 is moved in a round trip to stop at the two positions of the base position A and the front position C, and the rear lens group 2 is moved in a round trip to stop at the base position (1) and the front-most position (4). In this way, by carrying out control like the operation characteristics shown in
Further, the front lens group 1 is moved in a round trip to stop at the two positions of the base position A and the rear position B, and the rear lens group 2 is moved in a round trip to stop at the base position (1) and the two front positions (2), (3) for a total of three positions. In this way, by carrying out control like the operation characteristics shown in
Further, the front lens group 1 is moved in a round trip to stop at the two positions of the base position A and the rear position B, and the rear lens group 2 is moved in a round trip to stop at the base position (1) and the two front positions (2), (3) for a total of three positions. In this way, by carrying out control like the operation characteristics shown in
Next, a more concrete structure for achieving the above-described operating principle will be described.
As shown in
Further, a miniature stepping motor 20 is provided on top of the low step portion 12. The stepping motor 20 has a case body 21 which is curved in the shape of a rough arc along the flat shape of the low step portion 12, and an output shaft 22 which protrudes to the outside is provided in the middle portion thereof. Although omitted from the drawings, a rotor is arranged in the middle inside the case body 21, and the output shaft 22 is inserted in the center of the rotor to form an integrated body. Further, a stator is arranged in both side portions extending left and right inside the case body 21. In this regard, the structure disclosed in Japanese Laid-Open Patent Application No. HEI 6-1055828 or Japanese Laid-Open Patent Application No. HEI 6-296358 can be used as a stepping motor having such structure. Of course, the stepping motor is not limited to such structures, and it goes without saying that it is possible to use various structures. Further, a screw thread is cut in the tip portion of the output shaft 22 to form a lead screw.
On the other hand, one end of a guide pin 15 is inserted and fixed inside each of the holes 13 provided in the high step portion 11. Further, insertion is carried out so that a rear group movable body 30 can move with respect to the guide pins 15. The rear group movable body 30 has a flat shape roughly the same as that of the base 10, has guide holes 31 which pass through at positions corresponding to the holes 13 of the base 10, and is provided with a through hole 32 at a position corresponding to the through hole 14 of the base 10. Further, the guide pins 15 are inserted and arranged inside the guide holes 31, and in this way, the rear group movable body 30 which is supported by the three guide pins 15 can move forward and backward along the guide pins 15 in a stable posture. Further, a rear lens group (which includes the case of one lens) omitted from the drawings is mounted inside the through hole 32. Accordingly, the rear lens group moves forward and backward following the forward and backward movement of the rear group movable body 30. Further, in the state where the rear group movable body 30 is mounted on the guide pins 15, the stepping motor 20 is in an inserted state between the base 10 and the rear group movable body 30.
Further, a through hole 34 is formed in the portion of the rear group movable body 30 corresponding to the output shaft 22 of the stepping motor 20, and a rectangular concave portion 35 is formed around the through hole 34 in the front side of the rear group movable body 30. Further, a lead nut 36 is inserted and fixed inside the concave portion 35. The lead nut 36 engages with the lead screw provided on the output shaft 22 of the stepping motor 20, whereby the lead nut 36 and the rear group movable body 30 move forward and backward following the positive and reverse rotations of the output shaft 22.
Further, a front group support body 40 which supports the front lens group is mounted to the tip of each guide pin 15. Because the front group support body 40 is fixed to the tip of each guide pin 15, the relative positional relationship with the base 10 and the relative positional relationship with the CCD do not change. Further, a through hole 41 is provided in the middle portion of the front group support body 40, namely, at a position corresponding to the through holes 14, 32 provided in the base 10 and the rear group movable body 30, and the front lens group is inserted and arranged inside the through hole 41.
Further, a spacer 41 is arranged on each guide pin 15 by insertion. The thickness of the spacers 43 is set so that the distance between the front lens group and the rear lens group in the state where the front group support body 40 and the rear group movable body 30 are touching via the spacers 43 matches the spacing d1 (see
As one example of the dimensional shape of the lens drive apparatus having the structure described above, the base 10 forms an 11 mm square. Further, the inner diameter of the through holes 32, 41, namely, the diameter of the rear lens group and the front lens group is 5 mm. Further, the total height of the apparatus (the distance from the bottom surface of the base 10 to the front surface of the front group support body 40) is approximately 11 mm. In this way, the apparatus can be adequately installed in a portable telephone.
Further, when considering the dimensional shape of existing portable telephones, the surface area of the camera module forms a size less than or equal to 13 mm square even for fixed focusing. When this level is used as an upper limit, the lens drive apparatus can be made one size larger with a lens diameter up to about 7 mm, and this makes it possible to keep the total size (flat shape of the base 10) under 13 mm square. Of course, the use of a smaller lens does not interfere with the design of further overall miniaturization.
By forming such structure, when the output shaft 22 of the stepping motor 20 is rotated in reverse to move the rear group movable body 30 backward to a base posture in contact with the front surface of the base 10 as shown in
From this state, when the output shaft 22 of the stepping motor 20 is rotated in the positive direction to move the rear group movable body 30 forward to form a state in which the front surface of the rear group movable body 30 is in contact with the spacers 43 as shown in
Further, because the stepping motor 20 is used as an actuator, by controlling the number of steps, it is possible to control the position of the rear group movable body 30 with good accuracy, and in the present embodiment, the rear group movable body 30 may be stopped at the two positions of the position where contact is made with the base 10, and the position where contact is made with the spacers 43, and because there is contact with another member at either stopping position, positioning can be carried out accurately even by relatively rough control of the number of rotations (number of steps).
Further, a compression coil spring 55 is inserted and arranged between the front lens support body 53 and the rear lens support body 54 so that they are both normally biased in separate directions by the elastic restoring force of the compression coil spring 55. Further, positioning stoppers 56 which can make contact with the front lens support body 53 and the rear lens support body 54 are mounted to both ends of the bobbin 50. In this way, the front lens support body 53 and the rear lens support body 54 biased by the compression coil spring 55 make contact with the respective corresponding positioning stoppers 56 and are stopped (see
Further, in the present embodiment, the front lens support body 53 and the rear lens support body 54 are both made from permanent magnets (the magnetic direction is to the left in the drawings), and the positioning stoppers 56 are made from nonmagnetic bodies. Furthermore, a center positioning stopper 57 made from a magnetic body is arranged at a middle position inside the bobbin 50, and a coil 58 is provided around the outer circumference of the bobbin 50. Further, the length of the center positioning stopper 57 in the axial direction is made to match the spacing d2 (see
When such structure is formed, in a non-magnetized state, the front lens support body 53 and the rear lens support body 54 are biased in respective separate directions by the elastic restoring force of the compression coil spring 55, and as shown in
From this state, as shown in
Of course, the electromagnetic force generated by passing an electric current through the coil 58 is set to exhibit a greater force than the elastic restoring force of the compression coil spring 55. Further, once the state of
Further, because a solenoid is used as an actuator, it can be constructed easily on a small scale, and the two positions where the zoom magnification is 1× and α× are set accurately by the positioning stoppers 56 and the center positioning stopper 57.
In this way, in the non-magnetized state where no electric current is flowing through the coil 58, as shown in
Further, from this state, as shown in
Further, in the state where such zoom magnification is α×, when an electric current is passed in the direction opposite that of
In this way, as shown in
Then, from this state, as shown in
Further, when an electric current is passed in the opposite direction from the state shown in
Further, in the structure shown in
Further, in the second through the fourth embodiments described above, the front lens support body 53 is fixed to one end of the bobbin 50, and by appropriately passing current in a prescribed direction, it goes without saying that it is possible to form a lens drive apparatus which can switch between the two kinds of states of the base posture zoom magnification 1× and the zoom magnification β×.
The basic apparatus structure is the same as that of the second embodiment shown in
Further, the difference is the position of the front lens group 51 (front lens support body 53) at the time of the base posture forming the zoom magnification 1×. Namely, as shown in
In this state, when an electric current is passed toward the left in the drawings, the front lens support body 53 and the rear lens support body 54 mutually move forward (toward the left in the drawings), and as shown in
Then, even if the electric current is switched OFF, the zoom magnification γ× state is maintained. Further, when an electric current is passed in the opposite direction, the base posture having the zoom magnification 1× shown in
Namely, the center positioning stopper 57″ is constructed from a nonmagnetic body, and both positioning stoppers 56′ are constructed from magnetic bodies. Further, the magnetic direction (direction of the arrows in the drawings) of the permanent magnets forming the front lens support body 53 and the rear lens support body 54 point forward in the same direction (toward the left in the drawings). Further, the compression coil springs 55′ bias the corresponding support bodies 53, 54 toward the center positioning stopper 57″. However, the elastic restoring force thereof does not negate the state in which the lens support bodies 53, 54 are magnetically attracted to the positioning stoppers 56′ and pull them apart, but is instead a force greater than the magnetic attractive force created between the lens support bodies 53, 54 and the positioning stoppers 56′ once the lens support bodies 53, 54 are separated from the positioning stoppers 56′ and push against the center positioning stopper 57″.
When such structure is formed, as shown in
From this state, when an electric current is passed through the coil 58, as shown in
Of course, even in this embodiment, the state shown in
In the second through the sixth embodiments described above, in each case the coil 58 wound around the bobbin 50 used a uniform winding in the axial direction, but the present invention is not limited to this, and by changing the number of windings in accordance with location, it is possible to give a gradient to the magnetic field. Namely, by making the magnetic field the strongest at the stopping positions, it is possible to make it easy to obtain a driving force required for zooming.
Further, in order to give a gradient to the magnetic field, the coil may be provided with coils 58a, 58b having a different number of windings, and these may be arranged in the axial direction as shown in
Namely, a cylinder 63 in which a front lens group 61 and a rear lens group 62 are mounted so as to be capable of movement in the axial direction, and an electromagnet 65 are arranged close together in parallel inside a rectangular frame 60. Further, the inner circumferential surface of the cylinder 63 is also formed to have a low friction coefficient so that the front lens group 61 and the rear lens group 62 can move forward and backward smoothly.
Further, both ends of the electromagnet 65 are provided with a core 65a, and the tips of the cores 65a overlap with the cylinder 63. The tip portions of the cores 65a form portions which generate an electromagnetic force by the electromagnet 65. Further, an image taking element 69 such as a CCD or the like is arranged at the rear end portion of the frame 60, and light which is incident via the front lens group 61 and the rear lens group 62 forms an image on the image taking element 69.
Further, the front lens group 61 and the rear lens group 62 are constructed to include a prescribed number of lenses and support bodies which support these. Further, a structure is formed in which the front lens group 61 and the rear lens group 62 are normally biased toward the center by compression coil springs 64 arranged between these groups and spring stopping portions 63a provided at both ends of the cylinder 63. Further, two positioning stoppers 66 and one center positioning stopper 67 are arranged at prescribed positions on a line connecting the tips of the cores 65a provided at both ends of the electromagnet 65, and permanent magnets 68 are provided buried inside the outer circumference of the front lens group 61 and the rear lens group 62. More specifically, as shown in
Further, the center positioning stopper 67 is formed from a permanent magnet, and the magnetic direction (direction of the arrow in the drawings) is the same direction (front direction) as that of the permanent magnets 68 buried respectively in the front lens group 61 and the rear lens group 62. Further, as shown in
When such structure is formed, in the base posture, as shown in
Then, from this state, when an electric current is passed through the electromagnet 65, a magnetic field like that shown in
Further, even if the electric current to the electromagnet 65 is switched OFF, the state shown in
Further, in the state shown in
When such structure is formed, in the base posture in which no electric current is flowing through the electromagnet 65, as shown in
From this state, as shown in
Of course, from this state it is possible to return to the state shown in
The basic structure is the same as that of the eighth embodiment, wherein the positioning stoppers 66 arranged at both ends of the cylinder 63 are constructed from magnetic bodies, and the center positioning stopper 67′ is also constructed from a magnetic body. Further, the front lens group 61 and the rear lens group 62 are connected to both ends of the compression coil spring 64′ arranged between both lens groups, and the front lens group 61 and the rear lens group 62 are biased in separate directions by the elastic restoring force of the compression coil spring 64′.
Further, the difference is the position of the front lens group 61 at the time of the base posture forming the zoom magnification 1×. Namely, as shown in
In this state, when an electric current is passed through the electromagnet 65, a magnetic field due to the electromagnet 65 is generated as shown in
Then, even if the electric current is switched OFF, the zoom magnification γ× state is maintained. Further, when an electric current is passed in the opposite direction, the base posture having the zoom magnification 1× shown in
When such structure is formed, from the state (zoom magnification 1×) of the base posture shown in
From
Further, positioning stoppers 75 are mounted at prescribed positions of both ends of the slide shaft 74, and a center positioning stopper 76 is provided at a middle point of the slide shaft 74. In this way, the front lens group 71 and the rear lens group 72 can move between the center positioning stopper 76 and the positioning stoppers 75. Further, the distance between the positioning stoppers 75 and the length and the arrangement position of the center positioning stopper 76 are set so as to obtain the operational characteristics shown in
Namely, as shown in
Further, as shown in
Further, as an example of the drive mechanism for switching the zoom magnification between 1× and α×, permanent magnets 77 are provided in the front lens group 71 and the rear lens group 72, and a movable member 78 formed from a magnetic body is inserted so as to freely appear and disappear (be inserted and removed) between the permanent magnets 77. Namely, because the facing surfaces have the same pole, the permanent magnets 77 repel each other. In this way, as shown in
In this state, as shown in
Further, in the present embodiment, it is possible to make various changes to the embodiment. Namely, as shown in
In this way, in the case where the movable member 78 formed from a magnetic body is removed, the permanent magnets 77 magnetically repel each other in the same way as in the twelfth embodiment, and the base posture shown in
As an example of another embodiment, as shown in
Further, as shown in
In this way, as shown in
Further, by using the compression coil springs 79 as described above, as shown in
In this state, as shown in
Further, as shown in
Further, in the technological concept shown in
In the twelfth embodiment and the various embodiments that followed described above, the specific drive mechanism for moving the movable members 78, 78′ can use the various structures shown in
Further, in the embodiment described above, the movable member 78 and the operation lever 82 are made to carry out linear motion, but as shown in
Further, as shown in
Furthermore, it is possible to use a linear actuator 86 as the actuator when the movable member 78 is moved automatically. Namely, as shown in
Further, as shown in
Further, the specific examples of each drive mechanism described above were shown as being applied to the twelfth embodiment, but it is of course possible to apply the same structures to the other embodiments.
FIGS. 36˜38 show a thirteenth embodiment of the present invention. The present embodiment achieves the operational characteristics shown in
The basic structure is the same as that of the first embodiment, wherein the difference is that the front lens group is also made movable. Namely, as shown in FIGS. 36˜38, a flat rectangular base 10 is formed from a high step portion 11 which raises ¼ of the area of the front surface thereof including one corner by one step, and a low step portion 12 on the remaining area. Further, small diameter holes 13 are formed in three of the four corners of the high step portion 11, and a large diameter through hole 14 is formed in the middle. The center of the through hole 14 forms the optical axis, and although omitted from the drawings, an image taking element or the like such as a CCD or the like is arranged at a prescribed position behind the through hole 14.
Further, a miniature stepping motor 20 is provided on top of the low step portion 12. The stepping motor 20 has a case body 21 which is curved in the shape of a rough arc along the flat shape of the low step portion 12, and an output shaft 22 which protrudes to the outside is provided in the middle portion thereof. Although omitted from the drawings, a rotor is arranged in the middle inside the case body 21, and the output shaft 22 is inserted in the center of the rotor to form an integrated body. Further, a stator is arranged in both side portions extending left and right inside the case body 21. In this regard, the structure disclosed in Japanese Laid-Open Patent Application No. HEI 6-1055828 or Japanese Laid-Open Patent Application No. HEI 6-296358 can be used as a stepping motor having such structure. Of course, the stepping motor is not limited to such structures, and it goes without saying that it is possible to use various structures. Further, a screw thread is cut in the tip portion of the output shaft 22 to form a lead screw.
On the other hand, one end of a main guide pin 15a, sub guide pin 15b is inserted and fixed inside each of the holes 13 provided in the high step portion 11. Further, insertion is carried out so that a rear group movable body 30 can move with respect to both guide pins 15a, 15b. The rear group movable body 30 has a flat shape roughly the same as that of the base 10, has guide holes 31 which pass through at positions corresponding to the holes 13 of the base 10, and is provided with a through hole 32 at a position corresponding to the through hole 14 of the base 10. Further, both guide pins 15a, 15b are inserted and arranged inside the through hole 32, and in this way, the rear group movable body 30 which is supported by both the main guide pins 15a and the sub guide pins 15b can move forward and backward along each of the guide pins 15a, 15b in a stable posture. Further, a rear lens group (which includes the case of one lens) omitted from the drawings is mounted inside the through hole 32. Accordingly, the rear lens group moves forward and backward following the forward and backward movement of the rear group movable body 30. Further, in the state where the rear group movable body 30 is mounted on each of the guide pins 15a, 15b, the stepping motor 20 is in an inserted state between the base 10 and the rear group movable body 30.
Further, a through hole 34 is formed in the portion of the rear group movable body 30 corresponding to the output shaft 22 of the stepping motor 20, and a rectangular concave portion 35 is formed around the through hole 34 in the front side of the rear group movable body 30. Further, a lead nut 36 is inserted and fixed inside the concave portion 35. The lead nut 36 engages with the lead screw provided on the output shaft 22 of the stepping motor 20, whereby the lead nut 36 and the rear group movable body 30 move forward and backward following the positive and reverse rotations of the output shaft 22.
Furthermore, the main guide pins 15a are arranged to stand up even in the corner portions of the low step portion 12 of the base 10, and the tip portion of the main guide pin 15a attached to the top of the low step portion 12 is mounted so that movement is possible with respect to the rear group movable body 30.
On the other hand, a front group movable body 40′ which supports the front lens group is mounted to the tips of each of the guide pins 15a, 15b provided on the high step portion 11. The front group movable body 40′ is different from that of the first embodiment, and is set so as to be capable of movement over a prescribed distance in the axial direction. More specifically, the main guide pin 15a is inserted in a state through the inside of a hole 44 formed to have an inner diameter roughly the same as the outer diameter of the main guide pin 15a.
Further, circular stoppers 45 are attached to the tips of the sub guide pins 15b. The outer diameter of the stoppers 45 is made one size larger than the outer diameter of the sub guide pins 15b. Further, the sub guide pins 15b described above are inserted in holes 46 formed in prescribed positions of the front group movable body 40′ to enable relative movement. As for the inner diameter of the holes 46, the rear portion roughly matches the outer diameter of the sub guide pins 15b, and the front portion is made one size larger than the outer diameter of the sub guide pins 15b so that it is possible to at least insert and arrange the stoppers 45. Further, springs 47 are mounted in a coaxial state at the tip side of the sub guide pins 15b. Both ends of the springs 47 make contact with the stoppers 45 and the inside surfaces of the holes 46 to bias the stoppers 45 and the inside surfaces apart.
In this way, because the positions of the stoppers 45 attached to the tips of the sub guide pins 15b do not change with respect to the base 10, the front group movable body 40′ is biased backward and fixed in the state shown in
Further, spacers 43 are inserted and arranged on the sub guide pins 15b in a state fixed to the rear side of the front group movable body 40′. Of course, they do not necessarily need to be fixed to the front group movable body 40′, and may be in a free state, or may be fixed at the rear group movable body 30 side. Further, the thickness of the spacers 43 is set so that the distance between the front lens group and the rear lens group in the state where the front group movable body 40′ and the rear group movable body 30 are both touching the spacers 43 matches the distance d3 shown in
Further, a through hole 41 is provided in the middle portion of the front group movable body 40′, namely, at a position corresponding to the through holes 14, 32 provided in the base 10 and the rear group movable body 30, and the front lens group is inserted and arranged inside the through hole 41.
By forming such structure, when the output shaft 22 of the stepping motor 20 is rotated in reverse to move the rear group movable body 30 backward to a base posture in contact with the front surface of the base 10 as shown in
From this state, when the output shaft 22 of the stepping motor 20 is rotated in the positive direction to move the rear group movable body 30 forward to a prescribed position (a position where there is no contact with the front group movable body 40′, or even when there is contact it is not biased forward) as shown in
In this state, the stepping motor 20 is rotated further in the positive direction to move the rear movable body 30 further forward. When this is done, as shown in
In the present embodiment, the lens drive apparatus is constructed so that the front lens group 1 and the rear lens group 2 are arranged in the front and rear of the optical axis L, the front lens group 1 is fixed at a fixed position, and the rear lens group 2 is moved in the optical axis direction by drive means described later.
The front and rear lens groups 1, 2 are constructed in the same way so that the lens groups are supported by being fitted inside annular frames 3, 4, and each lens group has a lens diameter of about 5 mm. Further, a plurality of guide pins 7, 7 is arranged along the optical axis L, and the front and rear frames 3, 4 which have holes provided in the outer circumference into which the guide pins 7, 7 are fitted are lined up in the optical axis direction.
In order to function as a lens unit of an ultraminiature camera, an image taking element 6 such as a CCD or the like is arranged behind the rear lens group 2. Accordingly, at the light-receiving position of the image taking element 6, the magnification of the formed image changes in accordance with the positional relationship of the three optical elements lined up on the optical axis L, and the change in this zoom magnification generally has the characteristics shown in
Namely, as for the general optical characteristics in the lens structure of the front and rear two groups, it is necessary to also move the front lens group 1 to obtain the proper zoom magnification from wide-angle (WIDE) to telescopic (TELE), and in this regard, driving needs to be carried out in which the rear lens group 2 is moved in a linear state (characteristic b) toward the side of the body being photographed, and the front lens group 1 is moved once toward the image taking element 6 side and then returns to the side of the body being photographed in a curved state (characteristic f).
However, in this arrangement, because it is not possible to carry out miniaturization when it becomes necessary to provide separate drive means to move the front lens group 1, in the present embodiment, the front lens group 1 is fixed (characteristic c) at a fixed position, and only the rear lens group 2 is moved in the optical axis direction, wherein the rear lens group 2 is stopped at the two fixed positions A, B. In this way, the zoom magnification can be set at A× at the fixed position A, and the zoom magnification can be set at B× at the fixed position B, and this makes it possible to achieve a lens drive apparatus having two values of zoom magnification.
To give a specific example, in the case where the distance between the image taking element 6 and the front lens group 1 is fixed at 11.259 mm, the zoom magnification becomes 1× at the time when the distance from the image taking element 6 to the rear lens group 2 is 2.367 mm, and the zoom magnification becomes 2× at the time when such distance is 4.184 mm.
Further, in the present invention, driving is carried out so that the rear lens group 2 is moved a minute distance for each of the stopped fixed positions A, B. The minute movement at each of these fixed positions A, B is set so that movement is carried out at feed pitch intervals of 50 μm or less for a section of at least 600 μm forward and backward. These numerical values are different than the ideal values in accordance with the design values of the optical system, but they are confirmed by experiment. Specifically, as shown in
Further, as confirmed by experiment, when the distance of minute movement at each of the fixed positions A, B is several 10 μm, this matches the position where the focal point is 30 cm, and when the distance is 10 μm, this matches the position where the focal point is 1 m.
Further, with regard to the driving of the rear lens group 2, the feed pitch of the minute movements is also set at several μm or less. In this way, by making the feed pitch smaller, it is possible to carry out focusing at such fixed positions, whereby the focus operation becomes easy.
Accordingly, even in a structure in which only the rear lens group 2 is driven by one actuator, a zoom operation having two values and a prescribed distance macro operation are carried out, and the focus operation is also easily carried out. Further, it is possible to use a stepping motor as an actuator to move the rear lens group 2 back and forth between the two fixed positions A, B.
A more specific structure for achieving the operation principle described above can be achieved by using the structure of the first embodiment shown in
In the present embodiment, spacers 43 are inserted and arranged on each guide pin 15. The thickness of the spacers 43 is adjusted. In the driving of the stepping motor 20, the movement position of the rear group movable body 30 can be positioned with good accuracy in accordance with the number of steps, the rear group movable body 30 is moved backward by rotating the output shaft 22 in the reverse direction and stopped at the fixed position A near the front surface of the base 10 as shown in
Further, driving is carried out to move minute distances for each of the fixed positions A, B. In this regard, the stepping motor 20 is a two-phase type with 12 steps, for example, and by using a lead screw having a 0.5 mm pitch, it is possible to achieve a feed of approximately 42 μm per one step in two-phase magnetization, and the switching to macro operation is carried out by feeding several steps.
In the focus operation, the feed pitch needs to be made smaller, and when the stepping motor has 20 steps and uses a 0.25 μm pitch, for example, a feed of 12.5 μm is carried out per one step. Further, if 1-2 phase driving is carried out, because a feed of 6.25 μm is carried out per one step, the focus operation is carried out more accurately.
In this way, by driving the stepping motor 20, it is possible to move the rear group movable body 30, namely, the rear lens group to the fixed positions A, B, and minute movement is carried out at each of the fixed positions A, B. Accordingly, a zoom operation having two values and a prescribed distance macro operation are carried out by one actuator, and by making the feed pitch of the minute movements several μm or less, it is possible to carry out focusing at such fixed positions, and the focus operation is also easily carried out.
Further, in the lens drive apparatus having the structure described above, in one example of the dimensional shape, the base 10 is 11 mm square, the inner diameter of the through holes 32, 41, namely, the diameter of the rear lens group and the front lens group is 5 mm, and the height of the entire apparatus (the distance from the bottom surface of the base 10 to the front surface of the front group support body 40) is approximately 11 mm. In this way, it can be adequately installed in a portable telephone.
Further, when considering the dimensional shape of existing portable telephones, the surface area of the camera module forms a size less than 13 mm square even for fixed focusing. When this level is used as an upper limit, the lens drive apparatus can be made one size larger with a lens diameter up to about 7 mm, and this makes it possible to keep the total size (flat shape of the base 10) under 13 mm square. Of course, the use of a smaller lens does not interfere with the design of further overall miniaturization.
As described above, in the lens drive apparatus according to the present invention, by limiting the stopping positions of the lens support members to a small number such as 1, 2 or 3 (limiting the zoom magnification), it is possible to carry out positioning by a simple mechanism without the need for a complex cam mechanism or highly accurate control or complex mechanisms, and this makes it possible to construct a simple miniature lens drive apparatus at low cost. For this reason, it becomes possible to install such apparatus as a lens drive apparatus corresponding to optical zoom in portable telephones and the like.
Further, in the lens drive apparatus according to the present invention, the front lens is fixed, and only the rear lens connected to drive means is moved and stopped at two fixed positions, and because there is movement over a minute distance at such fixed positions, a zoom operation having two values and a prescribed distance macro operation are carried out. Further, by making the feed pitch of the minute movements less than or equal to several μm, it is possible to carry out focusing at such fixed positions, and the focus operation is also easily carried out. As a result, the external shape can be ultraminiaturized, and this makes it possible to install the apparatus preferably in portable telephones which are becoming thinner and smaller scale.
Having described and illustrated the principles of the invention in various embodiments thereof, it should be apparent that the invention can be modified in arrangement and detail without departing from such principles. We claim all modifications and variations coming within the spirit and scope of the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2002-306420 | Oct 2002 | JP | national |
| 2003-46010 | Feb 2003 | JP | national |
This application claims priority of PCT/JP03/13369, filed on Oct. 20, 2003, and Japanese Patent Applications No. 2002-306420, filed on Oct. 21, 2002 and No. 2003-46010, filed on Feb. 24, 2003, the disclosures of which are incorporated herein in their entirety by reference.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP03/13369 | 10/20/2003 | WO | 9/13/2005 |
