JP2010164892A - Autofocus camera module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To further miniaturize an autofocus camera module and reduce its cost. <P>SOLUTION: In the autofocus camera module, a spiral inclined face 27 spiraling upward along an inner face of a cylinder in a cylinder part 22 is provided on an upper face of a bottom plate part 23 in the cylinder part, and a downward spiraling inclined face 45 is provided in a peripheral fringe part of a lower end face of a lens unit 40. Many guide grooves 44 directed in the direction of optical axis of the lens unit are provided on an outer peripheral face of the lens unit by arranging them in parallel in the circumferential direction, and a key groove 25 directed in the direction of optical axis is provided on an inner face of the cylinder. A base point of the lens unit is set based on relative angles in the circumferential directions of the cylinder and the lens unit while the downward spiraling inclined face at a lower end of the lens unit in the cylinder part is abutted on the upward spiraling inclined face on the upper face of a bottom plate. A guide key 50 is inserted into the key groove and the guide groove being the closest to the key groove at the base point to move the lens unit onto a bottom plate part side in the cylinder part and position the lens unit at the base point at the initial period of focusing operation time. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an autofocus camera module that is used in a mobile phone, a mobile terminal, and the like, can perform focus adjustment without using a screw structure, and can easily set a lens unit base point position when focus is activated.

  As actuators for conventional autofocus (hereinafter referred to as AF) camera modules, those using a voice coil motor and those using a piezoelectric element have been developed.

  In the case of a voice coil motor, a lens unit in which a lens is fixed in a lens barrel is fixed to a central portion of a coil bobbin that is a non-magnetic material, a drive coil is wound around the coil bobbin, and a permanent magnet is spaced outside the drive coil. A yoke made of a magnetic material that is spaced apart and supports a permanent magnet is inserted on the inner peripheral side of the drive coil to support the repulsive force between the generated magnetic field and the permanent magnet that is energized to the drive coil, and the coil bobbin. It is designed to balance with the leaf spring. For this reason, the lens unit is changed along with the coil bobbin in the optical axis direction in accordance with the amount of current supplied to the drive coil (for example, Patent Document 1).

In the case of a piezoelectric element, as shown in FIG. 7, a moving body 12 brought into contact with a drive shaft 11 fixed to the piezoelectric element 10 by a predetermined frictional force is integrated with the lens unit 13 to obtain a piezoelectric element. The piezoelectric element 10 is slowly expanded by slowly increasing the driving voltage for the element 10, thereby moving the moving body 12 in contact with the driving shaft 11 together with the driving shaft 11, and then the driving voltage is rapidly decreased. By rapidly contracting the piezoelectric element 10, the driving shaft 11 is returned to the original position while leaving the moving body 12. By repeating this operation, the moving body 12 is shifted to a required length. When the moving body 12 is shifted in the opposite direction, the driving voltage is rapidly increased and then slowly decreased. (For example, Non-Patent Document 1).
JP 2006-64937 A Konica Minolta Technology Report 2006 (VOL.3) Technology Introduction "Development of a general-purpose AF unit for mobile phones"

  Of the conventional AF camera modules described above, those using a voice coil motor as the actuator require many members to be installed in multiple layers on the outside of the lens unit, making it difficult to reduce the size and increasing the number of parts. There was a problem that it was also expensive.

  Also, actuators that use piezoelectric elements are those that move the moving body by repeatedly moving the piezoelectric element abruptly and slowly returning it, so the position of the moving body cannot be known from the drive power supply side. . In general, in the AF camera module, the lens is stopped at the base point position which is an infinite position at the time of starting the focus operation, and then the AF operation is performed. Therefore, the movement for moving the lens unit to the base point position is performed. A position sensor for detecting the position of the body is required, and a Hall element has been used as a conventional position sensor. For this reason, the number of parts is increased, and a space for mounting the position sensor is required.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above-described conventional problems, and aims to further reduce the size and cost of an AF camera module.

The feature of the invention described in claim 1 for solving the above-mentioned conventional problems and achieving the intended object is that a pedestal having a lower end surface fixed to an upper surface of a substrate on which an image sensor is installed, and a cylindrical shape A lens unit that supports the lens in the lens barrel, and an inner peripheral surface provided on the base accommodates the lens unit in a cylindrical cylinder portion so as to be movable only in the optical axis direction. In an AF camera module that is adapted to shift in the optical axis direction by an actuator,
The inner bottom portion of the cylinder portion has an inward flange-shaped bottom plate portion formed with a transparent window hole through which imaging light is transmitted at the center, and a spiral along the cylindrical inner surface of the cylinder portion on the upper surface of the bottom plate portion. An upward spiral inclined surface is formed, and a peripheral portion of the lower end surface of the lens unit is provided with a downward spiral inclined surface having the same pitch as the upward spiral inclined surface of the upper surface of the bottom plate portion, and the outer peripheral surface of the lens unit A plurality of guide grooves directed in the optical axis direction arranged side by side in the circumferential direction, and an inner surface of the cylinder has a key groove directed in the optical axis direction, and a downward spiral inclination of the lower end of the lens unit in the cylinder portion The base position of the lens unit is set by the relative angle in the circumferential direction of the cylinder and the lens unit in a state where the surface is in contact with the upward spiral inclined surface of the top surface of the bottom plate. It said keyway in one state, the nearest the guide groove in the keyway, is a lens unit in inserting the guide key to movably guide only in the optical axis direction.

  According to a second aspect of the present invention, in addition to the configuration of the first aspect, the base point position is a position where the lens unit is infinite with respect to the image sensor.

  As described above, the AF camera module according to the present invention includes a spiral upward spiral inclined surface along the cylindrical inner surface of the cylinder portion on the upper surface of the bottom plate portion of the cylinder portion, and at the peripheral edge portion of the lower end surface of the lens unit. Is provided with a downward spiral inclined surface having the same pitch as the upward spiral inclined surface of the upper surface of the bottom plate portion, and on the outer peripheral surface of the lens unit, a large number of guide grooves directed in the optical axis direction are arranged in the circumferential direction and The inner surface of the cylinder has a keyway directed in the optical axis direction, and the cylinder and the lens in a state where the downward spiral inclined surface of the lower end of the lens unit is in contact with the upward spiral inclined surface of the upper surface of the bottom plate in the cylinder portion. The base point position of the lens unit is set by the relative angle in the circumferential direction of the unit. At the position, the key groove and the guide groove closest to the key groove are By inserting a guide key that guides the lens unit so as to be movable only in the optical axis direction, the lens unit can be positioned at the base point at the initial stage of the AF operation by moving the lens unit toward the bottom plate in the cylinder unit. This eliminates the need for a position sensor for detecting the lens unit position as in the prior art, contributing to downsizing, reducing the number of parts, and reducing costs.

  Next, the best mode for carrying out the AF camera module according to the present invention will be described in detail with reference to the embodiments shown in FIGS. FIG. 1 shows a camera module according to the present invention. In the figure, reference numeral 20 denotes a pedestal. The pedestal 20 is integrally formed with a base portion 21 having a square ring shape and a cylinder portion 22 having a cylindrical inner surface in a continuous arrangement thereon. The pedestal 20 is fixed to a circuit board (hereinafter simply referred to as a board) 30 with an adhesive at the lower end surface of the base part 21. An image sensor 31 is fixed on the upper surface of the substrate 30.

  An inward flange-shaped bottom plate portion 23 is formed on the inner bottom portion of the cylinder portion 22, and a light transmitting window hole 24 is opened at the center portion of the bottom plate portion 23. The lens unit 40 is accommodated in the cylinder portion 22 on the upper side of the bottom plate portion 23. In this lens unit 40, a lens 42 is incorporated in a cylindrical lens barrel 41, and the lens unit 40 is moved in the optical axis direction so that a focusing operation for adjusting the distance from the image sensor 31 is performed. It has become.

  A flange-shaped annular protrusion 43 is integrally formed on the outer periphery of the lens barrel 41, and a large number of guide grooves 44 parallel to the optical axis direction of the lens unit 40 are provided on the outer peripheral surface of the annular protrusion in the circumferential direction. Are formed at regular intervals.

  On the other hand, a key groove 25 is formed on the inner peripheral surface of the cylinder portion 22 at two positions symmetrical about the central axis so as to be parallel to the central axis. A guide key 50 is inserted into the guide groove 44, and the lens barrel 41 can be displaced only in the axial direction in the cylinder portion 22 by the guide key 50.

  On the upper surface of the bottom plate portion 23 of the cylinder portion 22, spiral upward spiral inclined surfaces 27, 27 are formed along the inner peripheral surface of the cylinder portion. The upward spiral inclined surfaces 27 and 27 are formed in a target arrangement for each half circumference of the inner circumferential surface of the cylinder portion, and change at the same slope from the lowest part to the top part at the same height as the bottom plate part surface in the half circumference. It has a shape.

  On the other hand, on the bottom surface of the lens barrel 41 constituting the lens unit 40, downward spiral inclined surfaces 45, 45 having the same pitch are integrally formed at positions facing the upward spiral inclined surfaces 27, 27. The position where the downward inclined surfaces 45, 45 are in contact with the upward spiral inclined surfaces 27, 27 described above is the base point position of the lens unit 40, that is, the infinite position where an image at an infinite position is formed on the surface of the image sensor 31. It is set to become.

  This base point position is set by inserting the lens unit 40 into the cylinder portion 22 and not inserting the guide key 50, that is, in a state where the lens barrel 41 can freely rotate in the cylinder portion 22. In this state, the upward and downward spiral inclined surfaces 27 and 45 are joined, and the lens barrel 41 is rotated relative to the cylinder portion 22. As a result, the joining position of both the spiral inclined surfaces 27 and 45 is changed, and the distance of the lens barrel 41 to the image pickup device 31 is changed. In this way, the base point position is detected from the image formed on the surface of the image pickup device 31 while the lens barrel is rotated by the half length of the lens barrel that is the length of the spiral inclined surface.

  After detecting the base point position in this way, as shown in FIG. 5, the key grooves 25 and 25 on the inner peripheral surface of the cylinder portion 22 and the guide grooves 44 on the outer periphery of the lens barrel are the The guide key 50 is inserted into the close guide grooves 44 and 44 so that the lens barrel 41 cannot rotate with respect to the cylinder portion 22. As a result, the lens unit 40 is in the state of the base point by bringing the downward spiral inclined surface 45 of the lower surface of the lens barrel into contact with the upward spiral inclined surface 27 of the bottom plate portion.

  A cover member 55 is fitted on the outer surface of the cylinder portion 22. The cover member 55 prevents the lens unit 40 from coming off the cylinder portion 22 in a state in which the axial movement necessary for the AF operation of the lens unit 40 is possible. A window hole 57 that can be moved in and out in the axial direction is formed, and a locking hole 58 for so-called patching is formed at the bottom.

  Then, by covering the cover member 55 from the tip end side of the cylinder portion 22 to the sea surface, the locking projections 28 projecting from the outer periphery of the cylinder portion fit into the locking holes 58 and are prevented from coming off. In this state, the lower surface of the cover member top plate portion 56 abuts against the top surface of the cylinder portion 22 to prevent the guide key 50 from coming off, and the upper surface of the annular ridge 34 on the outer periphery of the lens barrel is formed on the inner peripheral lower surface of the pin window hole 57. The lens unit 40 is prevented from coming off by contact.

  A window hole 60 for AF operation is formed on the side surface of the cylinder portion 22, and an operating arm 61 fixed to the lens barrel 41 protrudes outside through the window hole 60. The lens unit 40 is moved in the axial direction by the operation of the actuator 62 using the lens, and the AF operation is performed.

  By this actuator 62, the base unit position set by the relative angle of the upward and downward spiral inclined surfaces facing each other by pushing the lens unit 40 to the back of the cylinder portion 22 at the initial stage of the AF operation, That is, the position sensor is automatically returned to an infinite position, and an AF operation can be performed from this position. The AF operation can be started without using it.

1 is a perspective view of an AF camera module according to an embodiment of the present invention in a state where an actuator is omitted. It is the 0 exploded perspective view which omitted the cover member of the camera module same as the above. It is a perspective view of the base in the camera module shown in FIG. It is a perspective view from the bottom face side of the lens barrel of the camera module shown in FIG. FIG. 2 is a perspective view of a state in which a lens barrel is rotatably inserted into a cylinder portion of a pedestal of the camera module shown in FIG. 1 and a guide key is inserted between the cylinder barrel and the cylinder portion. It is a longitudinal cross-sectional view which shows the state with an actuator of the Example shown in FIG. It is a longitudinal cross-sectional view which shows the AF camera module with an actuator using the conventional piezoelectric element.

20 pedestal 21 base portion 22 cylinder portion 23 bottom plate portion 24 light transmitting window hole 25 key groove 26 pin fitting hole 27 upward spiral inclined surface 28 locking projection 30 substrate 31 imaging element 40 lens unit 41 lens barrel 42 lens 43 annular Projection 44 Guide groove 45 Downward spiral inclined surface 50 Guide key 51 Pin 55 Cover member 56 Top plate portion 57 Window hole 58 Locking hole 60 Window hole 61 Operating arm 62 Actuator

Claims (2)

A pedestal having a bottom surface fixed to the upper surface of the substrate on which the image sensor is installed; and a lens unit that supports a lens in a cylindrical lens barrel; and an inner peripheral surface provided on the pedestal is cylindrical. In the autofocus camera module, the lens unit is accommodated in the cylinder part so as to be movable only in the optical axis direction, and the lens unit is moved in the optical axis direction by an actuator.
The inner bottom portion of the cylinder portion has an inward flange-shaped bottom plate portion formed with a transparent window hole through which imaging light is transmitted at the center, and a spiral along the cylindrical inner surface of the cylinder portion on the upper surface of the bottom plate portion. An upward spiral inclined surface is formed,
The peripheral edge of the lower end surface of the lens unit includes a downward spiral inclined surface having the same pitch as the upward spiral inclined surface of the upper surface of the bottom plate portion,
On the outer peripheral surface of the lens unit, a large number of guide grooves directed in the optical axis direction are arranged side by side in the circumferential direction, and on the inner surface of the cylinder, a key groove directed in the optical axis direction is provided.
The base position of the lens unit is determined by the relative angle in the circumferential direction of the cylinder and the lens unit in a state where the downward spiral inclined surface of the lower end of the lens unit is in contact with the upward spiral inclined surface of the upper surface of the bottom plate in the cylinder portion. Set,
An auto-focus characterized by inserting a guide key for guiding the lens unit so as to be movable only in the optical axis direction in the key groove and the guide groove closest to the key groove in the state of the base point. The camera module.   The autofocus camera module according to claim 1, wherein the base point position is a position where the lens unit is infinite with respect to the image sensor.

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