JP2006133574A - Imaging apparatus and its assembly method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging apparatus surely realizing the focus set of a lens. <P>SOLUTION: The imaging apparatus 1 is equipped with an imaging device 3, the lens 11 for forming an image on the imaging device, a lens holder 12 holding the lens, and a focusing member 13 equipped with an engaging part capable of relatively moving the lens holder in the optical axis direction of the lens and also abutting on a cam member 30 so as to move continuously in the optical axis direction by the driving of the cam member 30. The imaging apparatus 1 is equipped with a setting means 51 driving the cam member 30 to a position where the lens 11 is focused based on output from the imaging device 3 and setting a cam usable range at the time of photographing with such a position as reference. Then, the imaging apparatus which is miniaturized and surely realizes the focus set at the time of assembly or the like is provided. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an imaging apparatus that uses a cam member to adjust the focus of a lens.

  In general, a focus adjustment mechanism for focusing a lens at the time of photographing is incorporated in an imaging apparatus such as a camera. When assembling the image pickup apparatus, it is necessary to correct the variation between individual differences and set the focus adjustment mechanism so that the focus adjustment can be performed accurately. For example, Patent Document 1 proposes a structure that can easily perform focus adjustment during assembly with respect to a mechanism that performs focus adjustment using a cam member.

  The focus adjustment mechanism of Patent Document 1 is attached to the base plate so that the rotation position can be adjusted, and is engaged with the cam surface by rotating through a driving member and a feeding member provided with a lens feeding cam surface. A drive ring that advances and retreats in the optical axis direction as the cam projection slides, and a lens barrel (lens holder) that is supported by the drive ring and guided to move in the optical axis direction. Yes. According to this focus adjustment mechanism, the initial focus setting can be performed by moving the lens holder forward and backward in the optical axis direction by adjusting only the rotation position of the feeding member for fine adjustment during assembly.

No. 8-9695

  However, component tolerances are included in the lens holder, cam member, and the like to be assembled, and an assembly error (assembly tolerance) occurs during assembly. For this reason, it is necessary to make the cam surface a larger area in consideration of errors than the area actually used for focusing at the time of shooting. In the focus adjustment mechanism of Patent Document 1, since fine adjustment of the focus at the time of assembly is performed manually by an operator, it is difficult to accurately adjust the focus of the lens, and variations in initial focus setting are likely to occur. There's a problem.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image pickup apparatus that is small and can reliably set the focus of a lens.

  The object is to provide an imaging device, a lens for forming an image on the imaging device, a lens holder that holds the lens, and an engaging portion that can move the lens holder relatively in the optical axis direction of the lens. And a focus adjustment member that abuts against the cam member and is moved stepwise in the optical axis direction by driving the cam member, the lens being based on an output from the image sensor This can be achieved by an imaging apparatus provided with setting means for driving the cam member to a position in focus and setting a cam use range at the time of photographing based on the position.

  The setting means may set the cam use range by correcting a design value that predefines a cam curve of the cam member. More preferably, it further comprises a storage means, and the setting means is configured to store information relating to the cam use range in the storage means. In addition, a position regulating member is provided between the focus adjustment member and the image sensor so as to abut against the focus adjustment member and regulate the position of the focus adjustment member and the image sensor. May be.

  Further, the object is to provide an imaging device, a lens for forming an image on the imaging device, a lens holder that holds the lens, and an engagement that can move the lens holder relatively in the optical axis direction of the lens. And a focus adjustment member that abuts against the cam member and is moved stepwise in the optical axis direction by driving the cam member, wherein the lens holder and the focus are assembled. After adjusting the focus of the lens with the adjustment member, the cam member is further driven based on the output from the imaging device to adjust the focus of the lens, and the lens at the time of shooting with reference to the focus adjustment position This can be achieved by setting the cam use range of the cam member.

  According to the present invention, the lens holder that holds the lens is provided with the engaging portion that is relatively movable in the optical axis direction of the lens, and in contact with the cam member, the cam member is driven to steplessly in the optical axis direction of the lens. Based on the output from the image sensor and the focus adjustment member that is moved to the position of the lens, the cam member is driven to a position where the lens is in focus, and the cam use range of the cam member used for focus adjustment at the time of shooting is determined based on that position. Since the setting means for setting is provided, it is possible to provide an image pickup apparatus that is small and reliably performs focus setting during assembling.

  Hereinafter, an embodiment according to the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of an imaging apparatus 1 according to the present invention. The imaging apparatus 1 includes a lens 11 that forms an image of the subject BJ on the imaging element 3. The lens 11 is moved forward and backward in the direction of the optical axis by a lens driving device 10 to be described later, and is adjusted in focus. FIG. 1 illustrates a motor (for example, a stepping motor) 8 serving as a driving source of the lens driving device 10. In addition, the imaging apparatus 1 includes a control unit 50. The controller 50 controls the driving of the motor 8.

  The control unit 50 includes a signal processing circuit 52 that processes a signal from the image sensor 3, a motor drive circuit 53 that controls driving of the motor 8, a control circuit 51 that controls these as a whole, and a series of programs and controls for control. The memory 54 for storing the data is included. The signal processing circuit 52 can be formed by a DSP (Digital Signal Processor), for example. The control circuit 51 is formed by a CPU (Central Processing Unit), for example, and functions as a setting means for setting a cam use range (hereinafter referred to as a cam use range) used at the time of photographing as described later. The memory 54 is a means for storing the cam use range.

  With reference to FIG.2 and FIG.3, the detailed mechanical structure of the imaging device 1 is demonstrated in detail. FIG. 2 is a plan view showing the configuration of the image pickup apparatus 1, and FIG. 3 is a side view thereof. In FIG. 3, a part is hatched so that the configuration can be easily confirmed.

  The imaging device 1 includes a lens driving device 10 that moves the printed circuit board 2, the imaging device 3, the base plate 4, the optical filter 5, and the lens 11 in the optical axis direction LA. A CCD, CMOS, or the like as the image sensor 3 is disposed at a predetermined position on the printed board 2. A base plate 4 is disposed so as to surround the imaging element 3. The base plate 4 is made of a resin such as plastic, and serves as a base member that supports a plurality of components described later. An opening 4HL is formed in the base plate 4 at a position facing the imaging device 3, and an optical filter 5 such as an IR cut filter is disposed so as to cover the opening 4HL.

  A lens driving device 10 is mounted on the top of the base plate 4. The lens driving device 10 includes a lens 11, a lens holder 12, an adjustment ring 13 as a focus adjustment member, a pair of guide shafts 7A and 7B, the motor 8, the worm gear 9, the cam gear 30 as a cam member, and the like. Has been.

  The lens 11 is fixed and held in a cylindrical lens holder 12. A cylindrical adjustment ring 13 is disposed so as to surround the outer periphery of the lens holder 12. Threaded portions that mesh with each other are formed on the outer periphery of the lens holder 12 and the inner periphery of the adjustment ring 13. The lens holder 12 and the adjustment ring 13 are engaged with each other at a portion indicated by reference numeral SG, and can be moved relative to the adjustment ring 13 in the optical axis direction LA by rotating the lens holder 12.

  A pair of guide shafts 7A and 7B are raised from the base plate 4 in parallel with the optical axis direction LA. The adjustment ring 13 has a pair of guide receiving portions 14A and 14B formed so as to protrude in the radial direction from the outer periphery. The guide receiving portions 14A and 14B are engaged with the guide shafts 7A and 7B, respectively. More specifically, one guide receiving portion 14A is formed in a forked shape so as to sandwich the guide shaft 7A from both sides, and the other guide receiving portion 14B is formed in a hole shape so as to be fitted to the guide shaft 7B. ing. With such a configuration, the adjustment ring 13 can be slid with respect to the guide shafts 7A and 7B and moved in the optical axis direction LA. As described above, the lens holder 12 holding the lens 11 meshes with the inner peripheral wall of the adjustment ring 13. Therefore, it is possible to adjust the focus of the lens 11 by moving the lens holder 12 forward and backward in the optical axis direction LA with respect to the adjustment ring 13.

  The adjustment ring 13 has a spring locking portion 13a on a part of the outer periphery. One end of a coil spring 20 described later is locked to the spring locking portion 13a. The adjustment ring 13 has a cam follower 15 so as to protrude downward (from the printed circuit board 2 side) from a part of the outer periphery. The cam follower 15 extends downward along the optical axis direction LA. The tip 15a of the cam follower 15 is formed in a hemispherical shape so as to easily come into contact with a cam surface 32 of a cam gear 30 described later.

  A motor 8 is fixed on the base plate 4 so that the rotation axis is orthogonal to the optical axis direction LA. A worm gear 9 is fixed to the motor 8. The worm gear 9 meshes with a tooth row 35 formed on the outer periphery of the cam gear 30. The cam gear 30 is pivotally supported on a support shaft 31 fixed to the base plate 4 in parallel with the optical axis direction LA, and receives a driving force from the worm gear 9 and rotates in both directions as described above. A cam surface 32 is formed on the upper surface of the cam gear 30. The cam surface 32 is a spiral inclined surface. The cam follower 15 of the adjustment ring 13 is in contact with the cam surface 32. A pedestal 36 is formed below the cam gear 30, and the height is adjusted so that the tooth row 35 meshes with the worm gear 9.

  Further, a coil spring 20 that urges the adjustment ring 13 in a predetermined direction is disposed. One end of the coil spring 20 is locked to a spring locking portion 13a on the adjustment ring 13 side, and the other end is locked to a spring locking portion 4a formed on the base plate 4 side. The coil spring 20 is stretched so as to generate a biasing force that draws the spring locking portion 13a and the spring locking portion 4a. Further, as shown in FIG. 3, the coil spring 20 is disposed in an inclined state with respect to the optical axis direction LA. This state is formed by disposing the spring locking portion 4a of the base plate 4 outside the spring locking portion 13a on the adjustment ring 13 side as viewed from the center of the lens 11.

  If the coil spring 20 is disposed so as to be inclined with respect to the optical axis direction LA as described above, the biasing force of the coil spring 20 is efficiently used for stable movement of the lens 11 when the lens 11 is moved in the optical axis direction LA. Can be used well. When the coil spring 20 is tilted with respect to the optical axis direction LA, the urging force based on the coil spring 20 is divided into a force acting in a direction parallel to the optical axis direction LA and a force acting in a direction perpendicular to the optical axis direction LA. Available. The first component force acting in a direction parallel to the optical axis direction LA acts as a force for urging (pressing) the cam follower 15 provided on the adjustment ring 13 toward the cam surface 32. Therefore, the adjustment ring 13 can be moved to a predetermined position in the optical axis direction LA according to the rotation state of the cam gear 30 (change in the position of the cam surface 32). That is, the lens 11 can be accurately moved to a predetermined position in the optical axis direction LA.

  Then, the second component force acting in the direction perpendicular to the optical axis direction LA acts as a force that urges (presses) the adjustment ring 13 against a part of the guide shaft 7B as a backlash. As a result, the adjustment ring 13 can move smoothly without rattling in the optical axis direction LA. Accordingly, the lens 11 can be moved to a desired position in the optical axis direction LA while suppressing the displacement of the lens 11.

  In the structure shown in this embodiment as shown in FIG. 3, the guide receiving portion 14A of the adjustment ring 13 that engages with the guide shaft 7A has a bifurcated shape, and the adjustment ring that engages with the guide shaft 7B. The thirteen guide receiving portions 14B have a hole shape. The lens-side inner surface Wa (see FIG. 2) of the guide receiving portion 14B is pressed against the guide shaft 7A in a state where the urging force (force pulled forward) of the coil spring 20 is applied. Further, with respect to the guide receiving portion 14A, the urging force of the coil spring 20 acts as a clockwise force, so that the inner surface Wb (see FIG. 2) is pressed against the guide shaft 7B. Thus, since the adjustment ring 13 is supported at three places, the position in the plane perpendicular to the optical axis direction LA is stabilized. The guide receiving portion 14A and the guide receiving portion 14B are set to be substantially symmetrical with respect to the center of the lens 11, and the cam follower 15 and the spring locking portion 13a are set to be substantially symmetrical about the guide receiving portion 14B. Has been. Further, the guide receiving portion 14A may not have a bifurcated shape but may have a hole shape like the guide receiving portion 14B.

  As described above, the cam surface 32 formed on the cam gear 30 has a spiral shape. Therefore, the start and end portions of the cam surface 32 are steeply inclined surfaces 32t. 2 and 3 illustrate a state in which the cam follower 15 is in contact with a high position of the cam surface 32 formed in a spiral shape. 4 and 5 are views corresponding to FIGS. 2 and 3, in which the cam surface 32 of the cam gear 30 is located at a position lower than the cam follower 15. In particular, as can be seen from FIG. 5, the cam follower 15 is designed not to contact the lowest region of the cam surface 32. The setting will be described.

  On the side of the guide shaft 7A, a position restricting member 6 that comes into contact with the lower surface of the guide receiving portion 14 is raised from the base plate 4. The position where the lower surface of the guide receiving portion 14 abuts against the position regulating member 6 is the lower limit position of the adjustment ring 13. As described above, when the adjustment ring 13 is at the lower limit position and the cam gear 30 is rotated and the cam surface 32 comes to the lowest region (non-contact portion), a state where the cam follower 15 does not contact the cam surface 32 can be formed. . At this time, the focus of the lens 11 can be adjusted by rotating the lens holder 12 with respect to the adjustment ring 13 and moving it relative to the optical axis direction LA. If the operator accurately adjusts the adjustment ring 13 and the lens holder 12 during assembly, and the parts such as the cam gear 30 are manufactured without error, the cam follower 15 is brought into contact with the design range of the cam surface 32 to accurately You can adjust the focus.

  However, since the position adjustment between the adjustment ring 13 and the lens holder 12 is performed by an operator, it is impossible to expect complete focus adjustment. The cam curve that defines the cam surface 32 formed on the cam gear 30 also includes component tolerances. Therefore, the imaging apparatus 1 has a configuration for surely setting the focus adjustment of the lens. Hereinafter, this point will be described.

  FIG. 6 is a diagram illustrating a cam curve CM that defines the cam surface 32 by developing the outer peripheral surface of the cam gear 30. Here, a region indicated as a design value is a standard cam use range used for focus adjustment at the time of photographing. Note that the region indicated by the symbol NT is the above-described non-contact portion where the cam follower 15 does not contact even when the adjustment ring 13 reaches the lower limit position (initial position) where the adjustment ring 13 contacts the position restricting member 6.

  When the adjustment ring 13 and the lens holder 12 are accurately adjusted, there is a range from the position C1 on the cam surface corresponding to the design point start point P1 to the position C2 on the cam surface corresponding to the end point P2. The cam usage range. However, the cam curve is shifted like CA or CB as shown in the figure due to component tolerance. If the cam curve deviates in this way, even if the adjustment ring 13 and the lens holder 12 are adjusted as designed, the cam use range is deviated from the design value, so that the assumed focus adjustment cannot be realized. .

  Therefore, in the present embodiment, as shown in FIG. 1, the image pickup apparatus 1 is provided with a control circuit 51, and this control circuit 51 causes an insufficient adjustment of the adjustment ring 13 and the lens holder 12, a component error of the cam gear 30, and the like. Even so, the cam usage range can be set appropriately. FIG. 7 is a flowchart showing an example of the assembly process of the imaging apparatus 1. The point that the control circuit 51 sets the cam use range will be described with reference to FIG. 7 and FIGS. 1 to 5 described above.

  First, the lens 11 is fixed to the lens holder 12 (S101), and the adjustment ring 13 is assembled to the guide shafts 7A and 7B (S102). The adjustment ring 13 is brought into contact with the position restricting member 6 to obtain an initial position (S103). Then, the lens holder 12 is screwed into the adjustment ring 13 (S104). Next, after adjusting the rotational position of the cam gear 30 so that the cam surface 32 does not come into contact with the cam follower 15 of the adjustment ring 13, the lens holder 12 is rotated with respect to the adjustment ring 13 to adjust the focus (S105). ). Since the focus adjustment here is performed by the operator, it is a rough adjustment. Next, the adjustment ring 13 and the lens holder 12 are bonded together to fix the relative position between them (S106). This step S106 may be omitted.

  Thereafter, the cam gear 30 is rotated to bring the cam surface 32 into contact with the cam follower 15 and move the adjustment ring 13 steplessly in the optical axis direction LA to perform fine adjustment of the focus (S107). Specifically, the control circuit 51 controls the drive of the motor 8 via the motor drive circuit 53 to rotate the cam gear 30 to move the adjustment ring 13 in the optical axis direction LA. On the other hand, the control circuit 51 receives an image detection signal from the image sensor 3 via the signal processing circuit 52. Then, the control circuit 51 confirms the in-focus state and the moving position of the cam gear 30 at that time, and sets an appropriate cam use range at the time of photographing (S108). Since the cam use range set by the control circuit 51 as described above is based on the image detection signal from the image sensor 3, there is insufficient adjustment between the lens holder 12 and the adjustment ring 13, and there is a component tolerance of the cam gear 30. However, the cam use range at the time of photographing can be set appropriately without being affected by these effects. If the cam use range set here is stored in the memory 54 (S109), the imaging apparatus can always obtain an appropriate focus. In particular, as shown in FIG. 7, by setting the cam use range at the time of assembly, it is possible to manufacture the imaging device 1 in which the initial focus setting has been completed.

  When the stepping motor is used as the motor 8 and the drive of the cam gear 30 is controlled by the number of pulses, the control circuit 51 confirms the deviation amount from the start point P1 in the design value to the front and rear by the number of pulses. Yes (see FIG. 6). Therefore, the cam usage range may be set by correcting the start point P1 of the cam usage range of the design value back and forth by the control circuit 51 adjusting the number of pulses.

  Note that the process shown in FIG. 7 shows a flow for performing fine adjustment of the focus and accurately setting the focus. However, the focus adjustment is completed with a certain degree of accuracy even in the coarse adjustment in step 105. Therefore, the control circuit 51 may automatically set the cam use range based on a predetermined design value. For example, the control circuit 51 sets a new cam use range by adding an error correction range for a predetermined pulse before and after the design value. In this way, the imaging device 1 can be manufactured by omitting the steps 107 and 108.

  The imaging apparatus 1 described above includes a control circuit 51 as setting means for setting the cam use range, and the control circuit 51 appropriately sets the cam use range in consideration of component errors and assembly errors, so that the focus is ensured. Can be combined. In particular, by setting the cam use range by the control circuit 51 at the time of assembly, it is possible to provide an imaging apparatus in which the initial focus setting has been completed. Further, since rough adjustment is performed in step 105 in FIG. 7, the area of the cam surface required for fine adjustment does not require much from the area of the cam surface of the design value. Less. For this reason, it can be set as a small cam, and it can contribute to size reduction of the whole imaging device.

  The preferred embodiment of the present invention has been described in detail above, but the present invention is not limited to the specific embodiment, and various modifications can be made within the scope of the gist of the present invention described in the claims.・ Change is possible.

It is the block diagram shown about the structure of the imaging device which concerns on this invention. It is the top view which showed the structure of the imaging device shown in FIG. It is the side view shown so that the structure of the imaging device shown in FIG. 1 could be confirmed. FIG. 3 is a diagram corresponding to FIG. 2 and showing a state where cam surfaces are at different positions. FIG. 4 is a view corresponding to FIG. 3 and showing a state where cam surfaces are at different positions. It is the figure which showed the cam curve which expand | deploys the outer peripheral surface of the cam gearwheel arrange | positioned at an imaging device, and prescribes | regulates a cam surface. It is the flowchart which showed an example of the assembly process of an imaging device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Imaging device 2 Printed circuit board 3 Imaging element 7A, 7B Guide shaft 8 Motor 10 Lens drive device 11 Lens 12 Lens holder 13 Adjustment ring (focus adjustment member)
14A, 14B Guide receiving portion 15 Cam follower 30 Cam gear (cam member)
32 Cam surface 51 Control circuit (setting means)
LA Optical axis direction

Claims (5)

An image sensor;
A lens for forming an image on the image sensor;
A lens holder for holding the lens;
A focus adjustment member that includes an engaging portion that can move the lens holder relatively in the optical axis direction of the lens, and that is in contact with the cam member and is continuously moved in the optical axis direction by driving the cam member. An imaging device comprising:
An imaging device comprising: setting means for driving the cam member to a position where the lens is in focus based on an output from the imaging device, and setting the cam use range at the time of photographing based on the position. apparatus. The imaging apparatus according to claim 1, wherein the setting unit sets the cam use range by correcting a design value that predefines a cam curve of the cam member. The imaging apparatus according to claim 1, further comprising a storage unit, wherein the setting unit stores information on the cam use range in the storage unit. A position restricting member is provided between the focus adjusting member and the image sensor, and a position restricting member that abuts the focus adjusting member and restricts a position between the focus adjusting member and the image sensor. Item 4. The imaging device according to any one of Items 1 to 3. An image pickup device, a lens for forming an image on the image pickup device, a lens holder for holding the lens, an engagement portion capable of relatively moving the lens holder in the optical axis direction of the lens, and a cam An image pickup apparatus assembly method comprising: a focus adjustment member that is in contact with a member and is moved steplessly in the optical axis direction by driving the cam member;
After adjusting the focus of the lens with the lens holder and the focus adjustment member, the cam member is further driven based on the output from the imaging device to adjust the focus of the lens, and the focus adjustment position is determined. An assembling method of an imaging apparatus, wherein a cam use range of the cam member at the time of photographing is set as a reference.

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