JP2010085473A - Imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact imaging apparatus which achieves shortening of time required to attain focusing. <P>SOLUTION: The imaging apparatus includes: a drive means for driving a focus lens; a target position decision means for deciding a target position of the focus lens; a position detection means for detecting a real position of the focus lens; a feedback control means for performing control to lessen a difference between the target position decided by the target position decision means and the real position detected by the position detection means; a posture detection means for detecting posture of the focus lens based on information obtained from the feedback control means; and a drive start position control means for changing a drive start position of the focus lens in accordance with output from the posture detection means. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an imaging apparatus, and more particularly, to an imaging apparatus that changes a driving start position by determining a posture from gravity applied to a focus lens.

  As a lens barrel of an imaging device such as a compact type still camera, it is possible to switch between an imaging state in which zoom drive and focus drive are performed and a storage state in which the distance between the zoom lens, focus lens, and image sensor is reduced according to the situation. There is a variable retractable lens barrel.

  In recent years, with the enhancement of functionality of imaging devices, a lens driving method that achieves high speed, low noise, and high stop accuracy is required.

  For this reason, in addition to the conventional DC motor and stepping motor, as a driving method of the focus lens, a driving method in a so-called voice coil motor in which a coil is arranged in a magnetic circuit including a magnet and a yoke has been proposed (Patent Literature). 1-3.)

  Also, as the focus lens position control method, when the target position is commanded to the focus lens driver unit and driven, feedback that makes the deviation between the target position and the actual position zero by acquiring the actual position of the focus lens There is a control method to perform.

  Generally, in feedback control, a control method called PID control is used. D control (differential control) is used to improve the gain margin and phase margin due to overcompensation of P control (proportional control) and to improve the stability of feedback control. The I control (integral control) is used to improve the offset characteristic of the feedback control. Feedback control executed by selecting and combining these P control, I control, and D control as needed is called PID control.

  With such a feedback control method, the focus lens can be driven to a predetermined target position.

  On the other hand, as a method for scanning the target position of the focus lens, contrast with the focus lens position where the high frequency component (hereinafter referred to as “focus evaluation value”) of the luminance signal obtained from the image sensor is maximized is the focus position. There is a method. Further, as this contrast method, there is a whole-area scan method in which the focus evaluation value is stored over the entire scanning range of the focus lens, and the focus lens position corresponding to the maximum value is set as the focus position.

  When a method such as the whole area scanning method is used, the focus lens is scanned over the entire driving range from infinity to the nearest, and the maximum value of the focus evaluation value is detected. For this reason, there is a problem that the time until focusing is increased.

On the other hand, with respect to the above problem, a method has been proposed in which the driving start position is changed according to the orientation of the imaging device before the focus lens starts scanning based on the orientation information from the sensor attached to the imaging device ( (See Patent Document 4).
JP-A-7-239437 JP 2006-65115 A Japanese Patent No. 3767532 JP 2005-266465 A

  As disclosed in Patent Document 4, if a method of changing the drive start position in accordance with the attitude of the imaging device is employed, the time until focusing can be shortened.

  However, in a compact digital camera that is desired to be downsized, it is not desirable to separately mount a sensor that detects the attitude of the imaging device.

  Therefore, in the present invention, a feedback control method is applied as the control method of the focus lens, and the attitude of the imaging device is detected from the degree of the influence of gravity on the focus lens. As a result, the posture is detected from the gravity applied to the focus lens, and the current distance of the subject is predicted according to the posture. Then, a small imaging device capable of shortening the time until focusing is provided by changing the driving start position of the focus lens in accordance with the predicted subject distance.

  An imaging apparatus according to one aspect of the present invention includes a driving unit that drives a focus lens, a target position determination unit that determines a target position of the focus lens, a position detection unit that detects an actual position of the focus lens, Feedback control means for controlling the difference between the target position determined by the target position determination means and the actual position detected by the position detection means, and based on information obtained from the feedback control means, There is provided an attitude detection means for detecting the attitude of the focus lens, and a drive start position control means for changing the drive start position of the focus lens in accordance with an output from the attitude detection means.

  Other objects and features of the present invention are illustrated in the following examples.

  According to the present invention, it is possible to provide a small imaging device that shortens the time until focusing.

    Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each figure, the same members are denoted by the same reference numerals, and redundant description is omitted.

  First, the lens barrel in the present embodiment will be described. FIG. 1 is an exploded perspective view of a lens barrel that is an example of the present embodiment.

  The lens barrel shown in FIG. 1 has a three-stage collapsible lens group configuration. A first lens group 101 (zoom lens), a second lens group 102 (shift lens), and a third lens group 103 (focus lens) are arranged in this order from the subject side (left side in FIG. 1).

  The first lens group 101 is held by the first lens barrel 105. The second lens group 102 is held by the second lens barrel 106. The third lens group 103 is held by the third lens barrel 107.

  The subject image that has passed through the three lens groups (the first lens group 101, the second lens group 102, and the third lens group 103) is photoelectrically converted by the image sensor 104 via the low-pass filter 110. The image sensor 104 is held by an image sensor base plate 109. A cover barrel 111 is fixed to the image sensor base plate 109.

  A drive cylinder 112 is rotatably held on the cover barrel 111 and the image sensor base plate 109.

  The drive cylinder 112 has a cylindrical shape, and a gear 112a is provided on the outer periphery thereof. The drive gear 113 is engaged with the gear 112 a, and the drive cylinder 112 is rotationally driven by the rotation of the zoom motor 114.

  Further, three rectilinear grooves 112b extending in the optical axis direction are formed on the inner peripheral wall of the drive cylinder 112 at equal intervals in the circumferential direction. Inside the drive cylinder 112, a cover cylinder 111 and a fixed cylinder 115 fixed to the image sensor base plate 109 are arranged.

  In the fixed cylinder 115, three feed cams 115a each having a through groove shape are formed at equal intervals in the circumferential direction. Further, on the inner peripheral wall of the fixed cylinder 115, three feeding taper cams 115b are formed at equal intervals in the circumferential direction. Furthermore, three rectilinear grooves 115c extending in the optical axis direction are formed on the inner peripheral side of the fixed cylinder 115 at equal intervals in the circumferential direction.

  A movable cam cylinder 116 is disposed inside the fixed cylinder 115. The movable cam cylinder 116 has a cylindrical shape, and a follower pin 116a and a drive pin 116b serving as a cam follower are provided on the outer peripheral portion thereof. The drive pin 116b is located closer to the image sensor 104 than the follower pin 116a. A taper portion is formed at the tip of the follower pin 116 a, and this taper portion is engaged with the feeding taper cam 115 b of the fixed cylinder 115. The drive pin 116b engages with the feed cam 115a of the fixed cylinder 115 and also penetrates the feed cam 115a and engages with the rectilinear groove 112b.

  Thus, the drive pin 116b is engaged with the rectilinear groove 112b. Therefore, when the drive cylinder 112 is driven to rotate around the optical axis by the driving force of the zoom motor 114, the follower pin 116a of the movable cam cylinder 116 moves in the optical axis direction by the lift of the tapered cam 115b of the fixed cylinder 115.

  A rectilinear cylinder 117 is disposed inside the movable cam cylinder 116. The rectilinear cylinder 117 has a cylindrical shape, and three protrusions 117a are formed at equal intervals in the circumferential direction at the outer peripheral portion on the rear end side. The protruding portion 117 a is engaged with a rectilinear groove 115 c formed on the inner peripheral side of the fixed cylinder 115. For this reason, the rectilinear cylinder 117 is movable in the optical axis direction with respect to the fixed cylinder 115, but does not rotate around the optical axis.

  In addition, three protrusions 117b are formed at equal intervals in the circumferential direction on the outer periphery of the distal end portion of the rectilinear cylinder 117. The protrusion 117b is in contact with the tip of the movable cam cylinder 116. Therefore, when the moving cam cylinder 116 moves in the optical axis direction, the rectilinear cylinder 117 rotates in the optical axis direction integrally with the moving cam cylinder 116, but the rectilinear cylinder 117 does not rotate. The rectilinear cylinder 117 is formed with three through-groove rectilinear grooves 117c extending in the optical axis direction at equal intervals in the circumferential direction.

  On the other hand, three follower pins 105 a are formed at equal intervals in the circumferential direction on the outer peripheral portion of the first lens barrel 105. The follower pin 105a penetrates the rectilinear groove 117c of the rectilinear cylinder 117, and a tapered portion formed at the tip of the follower pin 105a is engaged with the taper cam 115b. Therefore, the first lens barrel 105 moves in the optical axis direction by the lift of the taper cam 115b in conjunction with the movement of the movable cam barrel 116 in the optical axis direction while rotating.

  Further, three follower pins 106 a are formed at equal intervals in the circumferential direction on the outer peripheral portion of the second barrel 106. The follower pin 106a penetrates the rectilinear groove 117c of the rectilinear cylinder 117, and a tapered portion formed at the tip of the follower pin 106a is engaged with the taper cam 115b. Therefore, the first lens barrel 105 moves in the optical axis direction by the lift of the taper cam 115b in conjunction with the movement of the movable cam barrel 116 in the optical axis direction while rotating.

  In addition to the second lens group 102, a shutter / aperture unit 108 is mounted on the second lens barrel 106.

  With the above configuration, the zoom magnification can be changed by using the driving force of the zoom motor 114 to change the interval between the three lens groups. In addition, it is possible to perform focusing by changing the position of the third lens group 103 in the optical axis direction by a voice coil motor described later.

  Next, the drive mechanism of the third lens group 103 and the image sensor base plate 109 will be described. FIG. 2 is an exploded perspective view of the driving mechanism of the third lens group 103 and the image sensor base plate 109. FIG. 3 is an assembly diagram of the driving mechanism of the third lens group 103 and the image sensor base plate 109.

  As shown in FIGS. 2 and 3, the voice coil motor includes a coil 118a, a magnet 118b, and a yoke 118c. The coil 118 a is fixed to the third lens barrel 107.

  When the coil 118 a is energized from the flexible substrate 119, the third lens barrel 107 moves along the guide shaft 121 by the action of a magnetic circuit formed by the magnet 118 b and the yoke 118 c fixed to the image sensor base plate 109 via the fixing member 120. Driven in the optical axis direction. The voice coil motor including the coil 118a is used as driving means for driving the focus lens of the imaging optical system.

  The driving range of the third lens barrel 107 is from the abutting surface between the image sensor base plate 109 and the third lens barrel 107 to the abutting surface between the member 122 fixed to the image sensor base plate 109 and the third lens barrel 107. It is. The position of the third lens barrel 107 in the optical axis direction is detected by the sensor 123a and the scale 123b as follows.

  The scale 123 b is elastically held by the third lens barrel 107 by the elastic holding member 124. Grooves are formed in the scale 123b at a predetermined pitch. In addition, a sensor 123a is attached to the imaging element base plate 109 with a fixing member 120 across a predetermined gap so as to face the scale 123b.

  A light emitting element and a light receiving element are mounted on the sensor 123a. A light beam emitted from the light emitting element is reflected by the groove portion of the scale 123b, and an output signal can be obtained by the light receiving element receiving the reflected light beam.

  When the third lens barrel 107 with the scale 123b fixed moves relative to the fixed sensor 123a, a sine wave signal having a phase difference of 90 degrees (deg) is output from the sensor 123a. Based on the output of these two-phase signals, the moving amount and moving direction of the scale 123b can be determined. As described above, the sensor 123a and the scale 123b are used as position detection means for detecting the actual position of the focus lens.

  The initial position of the third lens barrel 107 is determined by abutment between the third lens barrel 107 and the image sensor base plate 109.

  Note that the output of the sensor 123a is not limited to a two-phase signal, and a signal of three or more phases can also be used. Further, the phase difference (phase angle) may be an angle other than 90 degrees (deg), and an initial position detecting sensor may be attached to the initial position of the third lens barrel 107.

  Next, the configuration of the imaging apparatus in the present embodiment will be described. FIG. 4 is a block diagram of an imaging apparatus as an example of the present embodiment.

The first lens group 101 held by the first lens barrel 105 is a zoom lens that performs a magnification change capable of changing the position in the optical axis direction.
Reference numeral 401 denotes a zoom drive control unit which controls the drive of the first lens barrel 105 (first lens group 101).

  Reference numeral 108 denotes a shutter / aperture unit. Reference numeral 402 denotes a shutter / aperture unit drive control unit which controls the drive of the shutter / aperture unit 108.

  The second lens group 102 held by the second lens barrel 106 is a shift lens as a shake correction optical system capable of changing the position on a plane substantially perpendicular to the optical axis. Reference numeral 403 denotes a shift lens drive control unit, which drives and controls the second lens barrel 106 (second lens group 102).

  The third lens group 103 held by the third lens barrel 107 is a focus lens that performs focus adjustment whose position can be changed in the optical axis direction. Reference numeral 404 denotes a focus drive control unit, which drives and controls the third lens barrel 107 (third lens group 103).

The image sensor 104 converts an optical image that has passed through each lens group (the first lens group 101, the second lens group 102, and the third lens group 103) into an electrical signal.
Reference numeral 405 denotes an imaging signal processing unit that converts an electrical signal output from the imaging element 104 into a video signal. Reference numeral 406 denotes a video signal processing unit which processes the video signal output from the imaging signal processing unit 405 according to the application.

  Reference numeral 407 denotes a display unit that displays an image as necessary based on a signal output from the video signal processing unit 406. Reference numeral 408 denotes a display control unit which controls the operation and display of the imaging unit and the display unit. A control unit 409 controls the entire system.

Reference numeral 410 denotes a power supply unit that supplies power to the entire system according to the application.
Reference numeral 411 denotes an external input / output terminal unit for inputting / outputting communication signals and video signals to / from the outside. Reference numeral 412 denotes an operation unit for operating the system.
A storage unit 413 stores various data such as video information.

  Next, the operation of the image pickup apparatus of the present embodiment having the above configuration will be described.

  The operation unit 412 has a shutter release button configured such that the first switch SW1 and the second switch SW2 are sequentially turned on according to the amount of pressing. The shutter release button has a structure in which the first switch SW1 is turned on when the button is depressed about half, and the second switch SW2 is turned on when the button is fully depressed.

  When the first switch SW1 of the operation unit 412 is turned on, the focus drive control unit 404 drives the focus lens (third lens group 103) to perform focus adjustment. At this time, the shutter / aperture unit drive control unit 402 drives the shutter / aperture 108 to set an appropriate exposure amount.

  Further, when the second switch SW2 of the operation unit 412 is turned on, the image data obtained from the light image exposed to the image sensor 104 is stored in the storage unit 413. At this time, if there is an instruction to turn on the shake correction function from the operation unit 412, the control unit 409 instructs the shift lens drive control unit 403 to perform a shake correction operation. Receiving this, the shift lens drive control unit 403 performs a shake correction operation until an instruction to turn off the shake correction function is given.

  When the operation unit 412 has not been operated for a certain period of time, the control unit 409 issues an instruction to shut off the power source of the display for power saving.

  In the imaging apparatus of this embodiment, one of the still image capturing mode and the moving image capturing mode can be selected from the operation unit 412. In each mode, the operating conditions of each actuator control unit can be changed.

  If there is an instruction for zooming with the zoom lens to the operation unit 412, the zoom drive control unit 401 that has received the instruction via the control unit 409 drives the zoom lens (first lens group 101) and instructs Move the zoom lens to the specified zoom position. At the same time, the focus drive control unit 404 drives the focus lens (third lens group 103) based on the image information sent from the image sensor 104 and processed by the image signal processing unit 405 and the video signal processing unit 406. Adjust the focus.

  Next, the focus drive control unit 404 will be described. FIG. 5 is a detailed block diagram of the focus drive control unit 404 shown in FIG.

  As shown in FIG. 5, the focus drive control unit 404 is configured as feedback control means. The feedback control unit controls the difference (deviation) between the target position of the focus lens determined by the control unit 409 and the actual position of the focus lens detected by the sensor 123a.

  When the focus lens is scanned within the driving range of the focus lens for focusing, the target position of the focus lens is commanded from the control unit 409. As described above, the control unit 409 is used as target position determining means for determining the target position of the focus lens.

  On the other hand, since the focus lens position signal, which is the output value of the sensor 123a, is an analog signal, it is converted into a digital signal by the AD conversion unit 507. The focus lens position signal output from the sensor 123a indicates the actual position of the focus lens. For this reason, the actual position of the focus lens can be acquired as a digital signal via the AD conversion unit 507.

  Next, the difference (deviation) between the actual position of the focus lens and the target position is calculated by the deviation calculation unit 501. The deviation calculated by the deviation calculating unit 501 is executed by the proportional control unit 502 (P control unit), the differential control unit 503 (D control unit), and the integral control unit 504 (I control unit). Is done.

  The proportional control unit 502 (P control unit) performs control to bring the deviation closer to zero, that is, control to bring the target position closer to the actual position. Here, with only the proportional control unit 502 (P control unit), an offset component is constantly generated in the deviation. For this reason, the integral control unit 504 (I control unit) performs control to make this offset component asymptotic to zero.

  When the orientation of the imaging device (focus lens) changes, that is, when the direction of gravity applied to the focus lens changes, the offset component generated in the deviation varies according to the orientation change of the imaging device, as with the actual position of the focus lens. .

  FIG. 8 is a diagram illustrating the relationship between the attitude of the imaging apparatus and the output of the integration control unit.

  The output of the integration control unit 504 represents a correction value for an offset component that occurs in the deviation of the feedback control. For example, when the orientation of the imaging apparatus is horizontally, the output of the integration control unit 504 is A.

  When the imaging device is tilted upward in the horizontal direction, the direction of gravity applied to the focus lens (downward) does not match the orientation direction (upward) of the tilted imaging device. For this reason, the influence of gravity (gravity load) in the feedback control is reduced, and the offset component generated in the deviation is also reduced as compared with the case where the imaging device is arranged horizontally. At this time, the output of the integration control unit 504 becomes B smaller than the output A (A> B).

  On the other hand, when the imaging apparatus is tilted horizontally downward, the direction of gravity (downward) applied to the focus lens coincides with the tilted posture direction (downward). For this reason, the influence of gravity (gravity load) in the feedback control is increased, and the offset component generated in the deviation is also increased as compared with the case where the imaging device is arranged horizontally. At this time, the output of the integration control unit 504 becomes C which is larger than the output A (A <C).

  The orientation direction of the imaging device can be detected from the relationship between the orientation of the imaging device and the output of the integration control unit 504 as described above. That is, when the output of the integration control unit 504 is A, it is determined that the imaging device is positioned horizontally. When the output of the integration control unit 504 is B (A> B), it is determined that the direction of gravity applied to the focus lens is the imaging element side (the imaging device is tilted upward). On the other hand, when the output of the integration control unit 504 is C (A <C), it is determined that the direction of gravity applied to the focus lens is the subject side (the imaging device is tilted downward).

Specifically, for example, with respect to the output of the integration control unit 504, three posture directions of the imaging apparatus are used by using two threshold values of A ₁ (A> A ₁ ) and A ₂ (A <A ₂ ). (Horizontal, upward direction, downward direction) can be determined. The output of the integral control unit 504, when the threshold A ₁ is smaller than the output B, the imaging device is tilted upward, if the threshold A ₂ is greater than the output C, the imaging device is tilted downward It is determined that

  In this embodiment, when the integral control for correcting the offset component is not performed, that is, when the integral control unit 504 (I control unit) is not included in the feedback control, posture detection using the output value of the integral control unit 504 is performed. I can't do it. However, in this case, the orientation direction of the imaging device can be detected using the actual position of the focus lens detected by the sensor 123a (focus sensor).

  FIG. 9 is a diagram illustrating a relationship between the posture of the imaging apparatus and the output of the AD conversion unit.

  The output of the AD conversion unit 507 represents the actual position of the focus lens. For example, when the orientation of the imaging apparatus is horizontally, the output of the AD conversion unit 507 is α.

  When the imaging device is tilted upward in the horizontal direction, the direction of gravity applied to the focus lens (downward) does not match the orientation direction (upward) of the tilted imaging device. For this reason, the shift of the actual position of the focus lens in the gravitational direction (downward) is smaller than that in the case where the imaging device is arranged horizontally. At this time, the output of the AD conversion unit 507 is β smaller than the output α (α> β).

  On the other hand, when the imaging apparatus is tilted horizontally downward, the direction of gravity (downward) applied to the focus lens coincides with the tilted posture direction (downward). For this reason, the actual position of the focus lens deviates relatively in the direction of gravity as compared with the case where the imaging device is arranged horizontally. At this time, the output of the AD conversion unit 507 is γ that is larger than the output α (α <γ).

  The orientation direction of the imaging device can be detected from the relationship between the orientation of the imaging device and the output of the AD conversion unit 507 as described above. That is, when the output of the AD conversion unit 507 is α, it is determined that the imaging device is positioned horizontally. When the output of the AD conversion unit 507 is β (α> β), it is determined that the direction of gravity applied to the focus lens is the imaging element side (the imaging device is tilted upward). On the other hand, when the output of the AD conversion unit 507 is γ (α <γ), it is determined that the direction of gravity applied to the focus lens is on the subject side (the imaging device is inclined downward).

Specifically, for example, by using two threshold values α ₁ (α> α ₁ ) and α ₂ (α <α ₂ ) for the output of the AD conversion unit 507, the three posture directions of the imaging apparatus are used. (Horizontal, upward direction, downward direction) can be determined. The output of the AD conversion unit 507, if the threshold alpha ₁ is smaller than the output beta, the imaging device is tilted upward, if the threshold alpha ₂ greater than the output gamma, the imaging device is tilted downward It is determined that

  At least one of the actual position (digital signal output from the sensor 123a) and the output signal from the deviation integration control unit 504 (I control unit) is output to the attitude detection unit 509. The posture detection unit 509 detects whether or not the posture change of the imaging apparatus has occurred, and outputs the result of the posture change to the focus drive start position control unit 508. The focus drive start position control unit 508 determines the drive start position of the focus lens based on the result of the posture change obtained from the posture detection unit 509.

  As described above, the focus drive control unit 404 includes feedback control means for feeding back the actual position of the focus lens detected by the sensor 123a with respect to the target position of the focus lens instructed by the control unit 409. In addition, the focus drive control unit 404 includes an attitude detection unit 509 and a focus drive start position control unit 508.

  An attitude detection unit 509 (attitude detection means) detects the attitude of the focus lens based on information obtained from the feedback control means. Further, the focus drive start position control unit 508 (drive start position control unit) changes the drive start position of the focus lens in accordance with the output from the attitude detection unit 509. The focus drive start position control unit 508 determines whether to start driving the focus lens from the image sensor side, from the subject side, or from the midpoint position.

  Further, in the focus drive control unit 404, it is desirable to provide a differential control unit 503 (D control unit) with respect to the deviation in order to improve the responsiveness of the focus lens drive with respect to the target position. Finally, the sum calculation unit 505 adds the control results of the proportional control unit 502 (P control unit), the differential control unit 503 (D control unit), and the integration control unit 504 (I control unit).

  The value calculated by the sum calculation unit 505 is transmitted to the drive output unit 506. The drive output unit 506 can be driven to move the focus lens to the target position by passing a predetermined current through the coil 118a based on the value calculated by the sum calculation unit 505.

  Next, focus drive start position control in the imaging apparatus of the present embodiment will be described.

  The driving of the focus lens in this embodiment is preferably performed using a voice coil motor (VCM). However, the portion that determines the posture from the direction of gravity applied to the focus lens is a focus drive control unit 404 that performs feedback control. For this reason, the drive of the focus lens may be performed using another actuator that performs feedback control and brushless drive control, such as a DC motor or a stepping motor.

  FIG. 6 is a diagram illustrating the relationship between the direction of gravity applied to the focus lens and the drive start position of the focus lens in the present embodiment.

  FIG. 6A shows a state in which the imaging device is arranged in parallel to the horizontal plane. In this state, the direction of gravity applied to the focus lens is not on either the image sensor side or the subject side.

  On the other hand, as shown in the left side of FIG. 6B, the subject is at infinity when the direction of gravity applied to the focus lens is on the imaging element side, that is, when the imaging apparatus is tilted horizontally upward. Is expected. For this reason, the drive start position of the focus lens is set to a position for focusing at infinity.

  On the other hand, as shown on the right side of FIG. 6B, when the direction of gravity applied to the focus lens is on the subject side, that is, when the imaging device is tilted horizontally downward, the subject is expected to be close. The For this reason, the drive start position of the focus lens is set to a position that is in close focus.

  However, depending on the optical characteristics of the focus lens, the position focused at infinity may be the position on the image sensor side or the position on the subject side. The same applies to the position at which the subject is in close focus. In either case, the drive start position control can be executed in the same manner. Further, the position at which the object is focused in close proximity can be either on the image sensor side or the subject side, but the drive start position control can be similarly executed.

  Therefore, in the following description, it is assumed that the focus position at infinity is on the image sensor side and that the close focus position is on the subject side. However, the present invention is not limited to this.

  FIG. 7 is a flowchart illustrating a method for changing the drive start position of the focus lens in accordance with the direction of gravity applied to the focus lens in the present embodiment.

  First, in step S701, the focus drive control unit 404 starts a process (focus drive start position control) for determining the focus drive start position.

  In step S702, the focus drive start position is initialized. When the imaging apparatus is in the horizontal orientation, for example, the previous drive start position is set as the initialization position. However, the initialization position is not limited to the previous drive start position, and another position may be determined in advance as the initialization position.

  In step S703, the focus drive control unit 404 determines the direction of gravity applied to the focus lens (the posture of the focus lens). The determination value at this time may be calculated using either an offset component by the integration control unit 504 (I control unit) or an actual position. Here, a description will be given assuming that the direction of gravity applied to the focus lens is determined using an offset component.

  When the value of the offset component in the integration control unit 504 coincides with the value of the offset component when the imaging apparatus is in the horizontal direction or is within a predetermined range (in the vicinity), the attitude of the imaging apparatus is in the horizontal state. Determined. At this time, the focus lens drive start position does not change. That is, the initialization position in step S702 becomes the drive start position. And it transfers to operation | movement of 1st switch SW1 of step S707 as it is.

  When the value of the offset component in the integration control unit 504 is not within a predetermined range (in the vicinity) with a value when the imaging device is in the horizontal direction, it is determined that the orientation of the imaging device is not in a horizontal state. At this time, in step S704, it is determined whether the value of the offset component is on the upper side or the lower side as compared with the case where the imaging device is in the horizontal direction.

  When it is determined that the posture of the imaging apparatus is on the upper side in the horizontal direction, that is, the gravity applied to the focus lens is on the image sensor side, the drive start position of the focus lens is set on the image sensor side in step S705. That is, the initialization position set in step S702 is changed. On the other hand, if it is determined that the posture of the imaging device is on the lower side in the horizontal direction, that is, the gravity applied to the focus lens is on the subject side, the focus lens drive start position is set on the subject side in step S705. That is, the initialization position set in step S702 is changed.

  When the first switch SW1 is pressed in step S707, the focus lens is scanned in step S708 from the set driving start positions. When the second switch SW2 is pressed in step S709, the image data obtained from the image sensor 104 is stored in the storage unit 413.

  Thereafter, in step S710, the focus drive control unit 404 determines the value of the offset component, and checks whether this value has changed from the value of the offset component before the second switch SW2 is pressed. At this time, a predetermined threshold value is set in advance, and when the threshold value range is exceeded, it is determined that the value of the offset component has changed.

  When the value of the offset component does not change before and after the second switch SW2 is pressed, the focus lens is scanned from the same position after the next time. That is, when driving the focus lens after the next, the same position as the drive start position when the first switch SW1 was pressed last time is the drive start position when the first switch SW1 is pressed after the next time. Set as

  On the other hand, when the value of the offset component changes before and after the second switch SW2 is pressed, the process returns to step S703. Then, the focus drive control unit 404 determines the value of the offset component again in steps S703 and S704.

  If the focus drive start position is changed after the posture change of the imaging apparatus is stopped, the operation at that time is reflected on the display unit 407, and the quality of the display unit 407 may be impaired. For this reason, it is desirable to change the drive start position of the focus lens while the offset component continues to change.

  If the change cannot be made (moved) to the target drive start position while the offset component continues to change, the change is stopped even during the change. The remaining movement amount is changed (moved) after the first switch SW1 in step S707 is pressed. As a result, the change in the focus lens drive start position is not reflected on the display unit 407, and the quality of the display unit 407 can be maintained.

  When the focus lens is in focus at infinity and the position of the focus lens is on the image sensor side, and the image pickup device is tilted horizontally upward, the direction of gravity applied to the focus lens is the same as that on the image sensor side. Become. For this reason, the direction of gravity coincides with the image sensor side that is the driving start position of the focus lens.

  In addition, when the focus lens is in close proximity and the focus lens is on the subject side, and the image pickup apparatus is tilted horizontally downward, the direction of gravity applied to the focus lens is the same as that on the subject side. Become. For this reason, the direction of gravity coincides with the subject side which is the drive start position of the focus lens. Therefore, the focus lens moves in the direction along gravity when driven to its drive start position.

  When the direction of gravity applied to the focus lens (the posture of the focus lens) coincides with the movement direction of the focus lens to the drive start position, energization of the coil 118a is stopped when the focus lens moves to the drive start position. . For this reason, by temporarily turning off the coil 118a, it is possible to reduce power consumption required when the focus lens is driven to the drive start position.

  Note that turning off the energization is not limited to the case where the gravity direction and the moving direction of the focus lens to the drive start position exactly match. When the direction of gravity and the direction of movement are close to a predetermined value or more, the coil 118a may be turned off.

  As described above, according to the present embodiment, the feedback control method is applied as the focus lens control method. Therefore, it is possible to determine the orientation of the imaging device from the direction of gravity applied to the focus lens itself without separately mounting a sensor for detecting the orientation of the imaging device. As a result, it is possible to reduce the time until focusing by changing the focus lens drive start position from the orientation of the imaging apparatus, despite the compact configuration.

  Therefore, according to the present embodiment, it is possible to provide a small-sized imaging device that shortens the time until focusing.

    The embodiment of the present invention has been specifically described above. However, the present invention is not limited to the matters described as the above-described embodiments, and can be appropriately changed without departing from the technical idea of the present invention.

It is a disassembled perspective view of the lens barrel in a present Example. It is a disassembled perspective view of the drive mechanism of a 3rd lens group and an image pick-up element base plate in a present Example. It is an assembly drawing of the drive mechanism of the 3rd lens group in this example, and an image sensor base plate. It is a block diagram of the imaging device in a present Example. It is a detailed block diagram of the focus drive control part in a present Example. In the present embodiment, it is a diagram showing the relationship between the direction of gravity applied to the focus lens and the drive start position of the focus lens. 5 is a flowchart illustrating a method of changing a focus lens drive start position in accordance with the attitude of the focus lens in the present embodiment. In this example, it is a figure showing the relation between the posture of an imaging device, and the output of an integral control part. In this example, it is a figure showing the relation between the posture of an imaging device, and the output of an AD conversion part.

Explanation of symbols

101 First lens group (zoom lens)
102 Second lens group (shift lens)
103 Third lens group (focus lens)
DESCRIPTION OF SYMBOLS 104 Image pick-up element 105 1st lens barrel 106 2nd lens barrel 107 3rd lens barrel 108 Shutter and aperture unit 109 Image pick-up element base plate 110 Low pass filter 111 Cover lens barrel 112 Drive cylinder 115 Fixed cylinder 116 Moving cam cylinder 117 Rectilinear advance cylinder 118a Coil 118b Magnet 118c Yoke 119 Flexible substrate 120 Fixed member 121 Guide shaft 122 Member 123a Sensor 123b Scale 124 Elastic holding member 401 Zoom drive control unit 402 Shutter / aperture unit drive control unit 403 Shift lens drive control unit 404 Focus drive control unit 405 Imaging signal processing Unit 406 video signal processing unit 407 display unit 408 display control unit 409 control unit 410 power supply unit 411 external input / output terminal unit 412 operation unit 413 storage unit 501 deviation calculation unit 50 Proportional control unit 503 differential control unit 504 integral control unit 505 sum calculating section 506 drives the output section 507 AD conversion section 508 focus drive start control unit 509 position detection unit

Claims (8)

Driving means for driving the focus lens;
Target position determining means for determining a target position of the focus lens;
Position detecting means for detecting the actual position of the focus lens;
Feedback control means for controlling the difference between the target position determined by the target position determination means and the actual position detected by the position detection means,
Attitude detection means for detecting the attitude of the focus lens based on information obtained from the feedback control means;
An image pickup apparatus comprising: a drive start position control unit that changes a drive start position of the focus lens in accordance with an output from the posture detection unit. The feedback control means includes an integral control unit that operates to reduce the offset component of the difference,
The imaging apparatus according to claim 1, wherein the attitude detection unit detects an attitude of the focus lens based on an output of the integration control unit. The feedback control means includes an AD converter that converts the output of the position detection means into a digital signal,
The imaging apparatus according to claim 1, wherein the attitude detection unit detects an attitude of the focus lens based on an output of the AD conversion unit.   The drive start position control means is configured to change the drive start position of the focus lens to a position at which the focus lens is focused at infinity when it is determined that the focus lens is in a posture in which gravity is applied to the imaging device side. The imaging apparatus according to any one of claims 1 to 3.   The drive start position control unit is configured to change the drive start position of the focus lens to a close focus position when it is determined that the focus lens is in a posture in which gravity is applied to a subject side. The imaging device according to any one of claims 1 to 4.   The drive start position control means sets the drive start position of the focus lens to the previous drive start position when it is determined that the focus lens is in a posture in which gravity is not applied to either the image sensor side or the subject side. The imaging apparatus according to claim 1, wherein the imaging apparatus is set.   The imaging apparatus according to claim 1, wherein the focus lens moves to the drive start position while the posture of the focus lens is changing.   When the direction of gravity applied to the focus lens coincides with the direction of movement of the focus lens to the drive start position, energization of the drive means is stopped when the focus lens moves to the drive start position. The image pickup apparatus according to claim 1, wherein the image pickup apparatus is an image pickup apparatus.