JP5747146B2 - Autofocus device, imaging device equipped with the autofocus device, and portable electronic device equipped with the imaging device - Google Patents

Description

  The present invention relates to an autofocus device, an imaging device equipped with the autofocus device, and a portable electronic device equipped with the imaging device, such as a digital camera, a mobile phone with a camera function, and a personal digital assistant (PDA). is there.

  Conventionally, some autofocus devices use a shape memory alloy for an actuator. In this autofocus device, by supplying power to the actuator, the actuator generates heat and contracts to move the lens in a predetermined direction, and the actuator naturally dissipates and extends to move the lens in the opposite direction. It is configured.

  And an imaging device provided with such an autofocus device controls the position of the lens by a resistance value corresponding to the deformation amount of the actuator, that is, a resistance value that descends by contraction and rises by extension (for example, Patent Document 1).

  Specifically, when the imaging device places the lens at a predetermined position, the voltage is applied to cause the actuator to generate heat or to stop applying the voltage so as to obtain a resistance value corresponding to the predetermined position of the lens. To let the actuator naturally dissipate heat. Then, the imaging device recognizes that the lens is positioned at a predetermined position when the resistance value of the actuator becomes a predetermined value (predetermined resistance value) corresponding to the predetermined position of the lens.

Here, in such automatic focusing device, in order to acquire the imaging data for each field in the focus area, as shown in FIG. 7 (a), corresponding to each field from the position P ₁ to a corresponding lens in the first field The focus area C divided by the positions P _{2 to} P ₆ to be moved is moved step by step.

Specifically, autofocus device drives the actuator, moving the lens toward the position P ₂ corresponding to the next second field for acquiring imaging data from the position P ₁ corresponding to the first field Let The autofocus apparatus, the lens is converged at a position P ₂ corresponding to the second field starts acquiring imaging data from (the period for acquiring the imaging data, as "imaging data acquisition period t _a" FIG. 7 (a)).

  The autofocus device calculates a target position for finally positioning the lens from the field-by-field imaging data thus obtained, and positions the lens at the target position.

JP 2007-217114 A

However, in recent years, the imaging data processing speed for acquiring and processing imaging data from the imaging element has been increasing year by year. When the imaging data processing speed is increased, the lens driving speed at which the actuator moves the lens position to the position corresponding to each field cannot follow, and the lens position is changed to the second field as shown in FIG. ( ₂₎ The acquisition of imaging data is started before being converged to a position P ₂ corresponding to and held in a certain range (the period for acquiring this imaging data is “imaging data acquisition period t _b ” as shown in FIG. referred to b)), not obtained but to start acquiring the imaging data wait until it converges to the position P _2.

Imaging device, when the position of the lens of the imaging data acquisition period t _b and acquires the captured data before converging to a position P ₂ corresponding to the second field, the light from the position P ₂ corresponding to the second field Imaging data at a position deviated in the axial direction (any one of the ranges p indicated by solid arrows in FIG. 7B) is acquired. This imaging data may overlap with a position (any one of P _{1 to} P ₆ ) in which this range p corresponds to another field, and discrimination from imaging data acquired from a position corresponding to another field is possible. It becomes difficult and the result of the calculated target position becomes inaccurate.

  For this reason, even if the imaging data processing speed is increased, if the lens driving speed of the actuator is not accompanied, it is necessary to wait for the lens position to converge and maintain at a position corresponding to the second field. Imaging data must be acquired. Therefore, the imaging apparatus cannot acquire the imaging data from the field provided in the focus area C, and cannot increase the speed of the autofocus process for positioning the lens at the target position.

  It is an object of the present invention to provide an autofocus device that can increase the speed of autofocus processing, an imaging device equipped with the autofocus device, and a portable electronic device equipped with the imaging device.

In the autofocus device according to the first aspect of the present invention, a lens that can move in a region corresponding to the focus region, an image sensor that receives light through the lens, an actuator that moves the lens, and the actuator are driven. and driving means, controls the drive means to move the lens to obtain the imaging data, and calculates a target position for finally positioning the lens from the imaging data, the previous SL lens to the target position An autofocus device including a control unit that controls the driving unit to position the focus unit, wherein the control unit moves the lens in a fixed direction in a region corresponding to the focus region. The lens is moved stepwise so as to be separated at a holding position for holding the lens provided in a region corresponding to In addition, the imaging data is acquired in a field provided until the lens held at the holding position is moved to reach the next holding position, and the field for acquiring the imaging data is maintained at a predetermined interval. As described above, the timing for acquiring the imaging data can be adjusted while the timing for moving the lens from the holding position is set at a predetermined interval.

According to this configuration, the control unit can acquire imaging data from each field while moving the lens in a certain direction. Therefore, the autofocus device does not necessarily need to maintain the lens position in each field in order to acquire the imaging data, and the speed of the autofocus process can be increased. Further, the lens driving speed for each field by the actuator may not be constant (change) due to the influence of individual differences of the actuator, the usage environment of the actuator, and the like. Even in such a case, the control means moves the lens stepwise so as to divide it at the holding position, so that the adjustment period for adjusting the shift of the movement time required for the movement of the lens with the change of the lens driving speed Can be provided. That is, the control means includes a period from the time when the lens is held before the movement to the next lens holding position to the time when the lens is moved to the next holding position. At this time, since the control means has already acquired the imaging data from the field by this adjustment period, it is only necessary to expect the period necessary for the adjustment accompanying the shift in the movement time, and the lens position converges at the holding position. There is no need to wait for the image data to be acquired, and there is no need to wait for the imaging data to be acquired as in the prior art.

  Furthermore, the control means can adjust the displacement of the lens position accompanying the change in the lens driving speed at the timing of acquiring the imaging data. Therefore, the control means can maintain the field for acquiring the imaging data at the predetermined interval while setting the timing for moving the lens from the holding position at the predetermined interval.

In the autofocus device according to claim 2 of the present invention, a lens that can move in a region corresponding to the focus region, an image sensor that receives light through the lens, an actuator that moves the lens, and the actuator are driven. and driving means, controls the drive means to move the lens to obtain the imaging data, and calculates a target position for finally positioning the lens from the imaging data, the previous SL lens to the target position An autofocus device including a control unit that controls the driving unit to position the focus unit, wherein the control unit moves the lens in a fixed direction in a region corresponding to the focus region. The lens is moved stepwise so as to be separated at a holding position for holding the lens provided in a region corresponding to In addition, the imaging data is acquired in a field provided until the lens held at the holding position is moved to reach the next holding position, and the field for acquiring the imaging data is maintained at a predetermined interval. As described above, the timing for moving the lens from the holding position can be adjusted while the timing for acquiring the imaging data is set at a predetermined interval.

According to this configuration, the control unit can acquire imaging data from each field while moving the lens in a certain direction. Therefore, the autofocus device does not necessarily need to maintain the lens position in each field in order to acquire the imaging data, and the speed of the autofocus process can be increased. Further, the lens driving speed for each field by the actuator may not be constant (change) due to the influence of individual differences of the actuator, the usage environment of the actuator, and the like. Even in such a case, the control means moves the lens stepwise so as to divide it at the holding position, so that the adjustment period for adjusting the shift of the movement time required for the movement of the lens with the change of the lens driving speed Can be provided. That is, the control means includes a period from the time when the lens is held before the movement to the next lens holding position to the time when the lens is moved to the next holding position. At this time, since the control means has already acquired the imaging data from the field by this adjustment period, it is only necessary to expect the period necessary for the adjustment accompanying the shift in the movement time, and the lens position converges at the holding position. There is no need to wait for the image data to be acquired, and there is no need to wait for the imaging data to be acquired as in the prior art.

  Furthermore, the control means can adjust the displacement of the lens position accompanying the change in the lens driving speed at the timing of moving the lens from the holding position. Therefore, the control means can maintain the field for acquiring the imaging data at a constant interval while setting the field for acquiring the imaging data at a predetermined interval.

  The image pickup apparatus according to a fourth aspect of the present invention is characterized in that the autofocus device is mounted.

  According to this configuration, the same effect as described above can be obtained in the imaging apparatus.

  A portable electronic device according to a fifth aspect of the present invention is characterized in that the imaging device is mounted.

  According to this configuration, the same effect as described above can be obtained even in a portable electronic device.

  As described above, according to the present invention, the speed of the autofocus process can be increased.

BRIEF DESCRIPTION OF THE DRAWINGS It is a whole external view which shows the open state of the portable electronic device which concerns on one Embodiment of this invention, Comprising: (a) is a whole external view which shows a front side, (b) is a whole external view which shows a back side. Overall schematic view showing an imaging apparatus according to the embodiment FIG. 2 is a block diagram showing a system configuration of the imaging apparatus according to the embodiment. (A) is a phase diagram between the time of the autofocus device according to the embodiment and the position of the lens, (b) is a timing chart showing the transmission timing of the lens movement command of the autofocus device according to the embodiment, (C) is a timing chart showing acquisition timing of imaging data of the autofocus device according to the embodiment. (A) is a phase diagram between the time of an autofocus device according to another embodiment of the present invention and the position of the lens, and (b) is a timing indicating the transmission timing of the movement command of the autofocus device according to the embodiment. (C) is a timing chart showing the acquisition timing of imaging data of the autofocus device according to the embodiment. (A) is a phase diagram between the time of an autofocus device according to another embodiment of the present invention and the position of the lens, and (b) is a timing indicating the transmission timing of the movement command of the autofocus device according to the embodiment. (C) is a timing chart showing the acquisition timing of imaging data of the autofocus device according to the embodiment. (A) is a phase diagram between the time of the conventional autofocus device and the lens position, and (b) is a phase diagram between the time of the conventional autofocus device and the lens position when the acquisition timing of the imaging data is increased.

  Hereinafter, an embodiment of an autofocus device, an imaging device, and a portable electronic device according to the present invention will be described with reference to FIGS. Note that a case where the autofocus device according to the present embodiment is employed in an imaging device will be described. The case where the imaging device according to the present embodiment is employed in a portable electronic device will be described.

  First, a schematic configuration of the portable electronic device according to the present embodiment will be described with reference to FIG. FIG. 1 is an overall view of a portable electronic device according to the present embodiment. The mobile electronic device 1 according to the present embodiment is a so-called foldable mobile phone. FIG. 1A is a perspective view from a direction in which the foldable mobile phone is open and a main screen (a first display 10 to be described later) is visible. FIG. 4B is a perspective view from the back side (the side opposite to the surface on which the main screen is fitted) of the mobile phone shown in FIG.

  The mobile electronic device 1 according to the present embodiment is a mobile phone equipped with a digital camera function, that is, including an imaging device 2. The mobile phone 1 includes a first main body 3 and a second main body 5 that can be folded via the first main body 3 and the hinge mechanism 4.

  The first main body 3 includes an operation key unit 6 configured by numeric keys and the like for inputting operations of the mobile phone 1 and a microphone 7 for inputting a transmission voice on the inner surface side when the mobile phone 1 is folded. Is provided. In addition, the first main body 3 is provided with a sounder 8 for notifying an incoming state or the like on the outer surface side when the cellular phone 1 is folded.

  The second main body 5 is provided with a speaker 9 for outputting received voice and a first display 10 for displaying characters and images on the inner surface side when the cellular phone 1 is folded. The second main body 5 includes a second display 11 that displays characters and images on the outer peripheral surface when the cellular phone 1 is folded, a light emitting element 12 that emits light, and a subject. And an imaging device 2 that collects the light reflected by the light (light from the light emitting element 12 or light such as sunlight).

  The configuration of the portable electronic device 1 according to the present embodiment is as described above. Hereinafter, the configuration of the imaging device 2 according to the present embodiment will be described with reference to FIGS. 2 and 3. FIG. 2 is an overall schematic diagram of the imaging apparatus 2 according to the embodiment. FIG. 3 is a block diagram showing a system configuration of the imaging apparatus 2 according to the embodiment.

  The imaging apparatus 2 according to the present embodiment includes lenses 13 and 13 that can move in a region corresponding to a focus region, an imaging element 14 that receives light through the lenses 13 and 13, and a lens that can move together with the lenses 13 and 13 that are housed A barrel 15, a shape memory alloy (SMA) actuator 16 for moving the lenses 13 and 13 in the optical axis direction (A arrow direction in FIG. 2), a driving means 17 for driving the resistance value of the actuator 16, and the lenses 13, An autofocus device 19 having a control means 18 for controlling the drive means 17 based on the resistance value of the actuator 16 that changes due to the deformation of the actuator 16 to move the actuator 13, and a housing (frame) 20 for housing the lens barrel 15. The substrate 21 on which the image sensor 14 is mounted and fixed to the housing 20 and the image sensor 14 receive light. And a display device 22 for outputting display image data on the screen. The control means 18 may be built in the image sensor 14.

  The lenses 13 and 13 are integrated with the lens barrel 15 and configured to be movable in the optical axis direction in a focus area (hereinafter also referred to as “movement area”) in the imaging apparatus 2. Moreover, although the lenses 13 and 13 are provided with two in this embodiment, it is not restricted to such a case, The case where one or three or more is provided may be sufficient.

  The lens barrel 15 is formed in a cylindrical shape, and is arranged so that the axis coincides with the optical axis. In addition, the lens barrel 15 includes a guided portion (not shown or numbered) guided by a guide portion (not shown or numbered) provided in the housing 20 in order to move stably in the optical axis direction. .

  The actuator 16 is configured in a V shape (in FIG. 2, two sides of the V shape are overlapped). The actuator 16 is fixed to the lens barrel 15 and the housing 20 respectively. When the voltage is applied, the actuator 16 is supplied with heat (for example, voltage (power, current)) and deforms (expands and contracts) as a whole in the direction of the optical axis (the direction indicated by the arrow B in FIG. 2). The lenses 13 and 13 are moved by adjusting the distance between the barrel 15 and the housing 20. In addition, you may provide an external heater etc. separately as a means to supply calorie | heat amount.

  Specifically, the actuator 16 generates heat and contracts when a voltage is applied to move the lenses 13 and 13 in a predetermined direction, and naturally radiates and extends the lenses 13 and 13 to define the predetermined direction. Configured to move in the opposite direction. More specifically, the actuator 16 contracts to separate the lenses 13 and 13 and the image sensor 14, and extends to bring the lenses 13 and 13 close to the image sensor 14.

  The driving unit 17 receives the movement command (signal) from the control unit 18 and drives the actuator 16 to move the lens barrel 15 in the optical axis direction. The driving unit 17 moves the lenses 13 and 13 to a designated position based on the movement command (signal) from the control unit 18 and holds the lens 13 at that position until the next movement command (signal) is received.

  The driving means 17 controls the positions of the lenses 13 and 13 by controlling the deformation amount of the actuator 16 while monitoring the resistance value of the actuator 16 corresponding to the deformation amount of the actuator 16. Then, the control means 18 controls the drive means 17 to move the lenses 13 and 13 stepwise from the first holding position in order to acquire image data from the image sensor 14 for each field provided in the focus area. At the same time, a target position for finally positioning the lenses 13 and 13 is calculated from the acquired imaging data, and the lenses 13 and 13 are positioned at the target positions.

  At this time, the control means 18 controls so that the direction in which the lenses 13 and 13 are moved stepwise from the first holding position becomes the direction in which the lenses 13 and 13 are moved as the actuator 16 contracts. The driving means 17 controls the amount of power supplied by modulating the voltage applied to the actuator 16 by pulse control (PWM control), that is, the time (pulse width) for applying a predetermined voltage value. ing.

  The configuration of the imaging apparatus 2 according to the present embodiment is as described above. Next, the autofocus operation of the imaging apparatus 2 according to the present embodiment will be described in detail with reference to FIG. FIG. 4A is a phase diagram between the time of the autofocus device 19 according to the embodiment and the position of the lens. The direction of the arrow on the vertical axis corresponds to the optical axis direction in which the lens moves, and refers to the direction from the image sensor 14 toward the subject. FIG. 4B is a timing chart showing the timing at which the autofocus device 19 according to the embodiment transmits a movement command to the driving means 17. FIG. 4C is a timing chart showing the timing at which the autofocus device 19 according to the embodiment acquires image data from the image sensor 14. The autofocus device 19 is configured to continue to acquire imaging data during the ON period of FIG.

First, as shown in FIG. 4, the control unit 18 moves the lenses 13 and 13 that can move in the moving region (C region in FIG. 4A) from the first holding position _{Ph1 in a} stepwise manner. The lens 13 is controlled so as to be positioned at a predetermined position (hereinafter also referred to as “standby position”). In this embodiment, an example in which the standby position is P _f4 will be described. However, the standby position is not limited to this position.

  The state in which the lenses 13 and 13 are positioned at the standby position means that the imaging apparatus 2 is in an initial mode (for example, a state in which the power is turned on for a camera and a state in a camera mode for a mobile phone) This refers to the case of the standby mode (the camera or mobile phone is waiting for the still button to be operated).

When the image pickup apparatus 2 is in an image pickup mode (a state in which a still button is operated in a camera or a mobile phone), the control unit 18 stops applying a voltage to the actuator 16, and the actuator 16 extends with natural heat dissipation. As a result, the lenses 13 and 13 are moved from the standby position _Pf4 to the first holding position _Ph1 . The display device 22, a lens 13 and 13 secure the output displayed on the image data acquired until at the standby position P _f4 moves to a position P _f1 corresponding to the first field from the standby position P _f4 .

Next, lens positioning will be described in detail with reference to FIG. In FIG. 4, the nth holding position is denoted as P _hn, and the position corresponding to the mth field is denoted as P _fm . Further, the control unit 18 acquires from the image sensor 14 imaging data at a position (P _{am to} P _bm ) including a position P _fm corresponding to the m-th field of the lens position.

When the control unit 18 controls the deformation amount of the actuator 16, the lenses 13 and 13 move in a direction away from the image sensor 14. Specifically, the control means 18 moves the focus area delimited by the holding position (P _hm ) holding the lenses 13 and 13 stepwise while stopping at the holding position for a predetermined time.

Control means 18, a lens 13 at the timing _{T a1} for moving the position of the lens 13 and transmits the movement command to the effect of moving to the next holding position _{P h2} with respect to the drive means 17. Upon receiving this movement command, the driving unit 17 drives the actuator 16 to move the positions of the lenses 13 and 13 from the holding position _Ph1 to the holding position _Ph2 .

The control means 18 acquires imaging data in a field provided while the lenses 13 and 13 are moved in a certain direction in a region corresponding to the focus region. That is, the control means 18 is in the first field provided between the time when the lenses 13 and 13 reach the next (second) holding position _Ph2 from the first (first) holding position _Ph1. It starts acquiring imaging data from the imaging device 14 at the timing _{T b1} reaching the position _{P a1} preceding the corresponding position _{P f1.} The fixed direction in which the lenses 13 and 13 are moved by the control means 18 refers to the optical axis direction. In this embodiment, in particular, the resistance value corresponding to the deformation amount of the actuator is lowered (that is, the actuator is heated). It is assumed that the lenses 13 and 13 are separated from the image sensor 14. Of course, the control means 18 which concerns on this invention is not limited to this example, It does not prevent making the direction approaching the image pick-up element 14 into a fixed direction. In addition, the control unit 18 acquires imaging data for a predetermined period (P _{a1 to} P _b1 ) including the position P _f1 corresponding to the first field.

  In the present embodiment, there are five fields in the focus area, that is, six lens positions at which the lenses 13 and 13 stop (of course, the present invention is not limited to five or six positions). . At this time, the control means 18 records the focus evaluation value based on the imaging data acquired for each field.

Then, when the lenses 13 and 13 are moved over the entire moving region corresponding to the focus region of the imaging device 2, the control unit 18 captures the imaging data of all the fields (all the lens positions P _fn ) in the focus region. get. Further, the control means 18 calculates, for example, the lens position P _{fn at} which the focus evaluation value is maximized as the target position, and moves the lenses 13 and 13 to the target position.

  Thus, the control means 18 can acquire imaging data from each field while moving the lenses 13 and 13 toward a fixed direction. Therefore, the autofocus device 19 does not necessarily need to maintain the positions of the lenses 13 and 13 in each field in order to acquire imaging data, and the speed of the autofocus process can be increased.

  The portable electronic device 1, the imaging device 2, and the autofocus device 19 according to the present invention are not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention. Of course.

  In the autofocus device 19 according to the above-described embodiment, the control unit 18 has explained the example in which the lenses 13 and 13 are moved stepwise so as to be separated at the holding position held in the area corresponding to the focus area C. Without being limited thereto, the control unit may control the driving unit so as to move the lens position in a substantially straight line toward a certain direction without dividing the lens position by the holding position.

  In the autofocus device 19 according to the above embodiment, the control unit 18 has described an example in which the transmission timing of the movement command for moving the lens from the holding position and the timing for acquiring the imaging data are maintained at a predetermined interval. It is not limited to. For example, as shown in FIG. 5, the control means moves the lens in a stepwise manner so as to divide the lens at the holding position for holding the lens provided in the area corresponding to the focus area, and moves the lens held at the holding position. The timing at which the lens is moved from the holding position is acquired so that the imaging data is acquired in a field provided until the next holding position is moved and the field from which the imaging data is acquired is maintained at a predetermined interval. You may be comprised so that adjustment of the timing which acquires imaging data is possible, setting to a predetermined space | interval.

Specifically, the control means includes a storage medium (such as RAM or ROM) that stores a table in which the lens driving speed of the focus area C of the actuator is measured or calculated in advance. Based on the lens driving speed of the table, the control means determines the lens position P _an (n = 1 to 1) where the lens position starts acquisition of imaging data from the holding position P _hn (n = 1 to 5) for each field. 5) and the timing to reach the lens position P _bn (n = 1 to 5) where the acquisition of the imaging data is completed, and the imaging data acquisition timing T _bn (n = 1 to 5) is calculated as the calculated timing. Adjust to include.

Note that a reference lens driving speed (for example, the lens position P _f2 corresponding to the second field in FIG. 5A) is set in advance and the lens driving speed is delayed (third to third). Lens position P _{a2 at which} the lens position starts to be acquired from the holding position _Ph2 corresponding to the second field (at the lens positions _Pf3 , _Pf4 , and _Pf5 corresponding to the field 5). The timing T _b3 at which the imaging data is acquired so as to delay the lens positions P _a3 , P _a4 , P _a5 , P _b3 , P _b4 , and P _b5 from the timing at which the lens position P _{b2 at} which imaging data acquisition ends is reached. , T _b4 , T _b5 may be adjusted.

Further, when the lens driving speed is faster than the reference lens driving speed (at the lens position P _f1 corresponding to the first field), the imaging data is transferred from the holding position _Ph2 corresponding to the second field. The timing T _b1 for acquiring imaging data is adjusted so that the positions P _a1 and P _b1 of each lens are accelerated from the timing of reaching the lens position P _a2 for starting acquisition and the lens position P _b2 for completing acquisition of imaging data. You may do it.

  As described above, in the autofocus device, the lens driving speed for each field by the actuator may not be constant (change) due to the influence of individual differences of the actuator, the usage environment of the actuator, and the like. Even in such a case, the control means moves the lens stepwise so as to divide it at the holding position, so that the adjustment period for adjusting the shift of the movement time required for the movement of the lens with the change of the lens driving speed Can be provided. That is, the control unit includes a period from the time when the lens is held before the movement to the next lens holding position to the time when the lens is moved to the next holding position as an adjustment period. At this time, since the control means has already acquired the imaging data from the field by this adjustment period, it is only necessary to allow for the period necessary for the adjustment accompanying the shift of the movement time, and the lens position is the holding position. There is no need to wait for convergence, and there is no need to wait for acquisition and processing of imaging data as in the prior art.

  Further, the control means can read and predict the lens driving speed of the actuator corresponding to the position of each lens from the table, with respect to the lens position shift accompanying the change in the lens driving speed. Based on this predicted value, the control means can adjust the displacement of the lens position at the timing of acquiring the imaging data. Therefore, the control means can maintain the field for acquiring the imaging data at the predetermined interval while setting the timing for moving the lens from the holding position at the predetermined interval.

  Further, as shown in FIG. 6, the control means moves the lens from the holding position while setting the timing for acquiring the imaging data at a predetermined interval so that the field for acquiring the imaging data is maintained at the predetermined interval. It may be configured such that the timing to be adjusted is adjustable.

Specifically, the control means includes a storage medium (such as RAM or ROM) that stores a table in which the lens driving speed of the focus area C of the actuator is measured or calculated in advance. Based on the lens driving speed of this table, the control means determines the timing T _an (n = 1 to 5) at which the movement command is transmitted, and the position of the lens for each field from the holding position P _hn (n = 1 to 5). Transmission is performed before the time required to reach the lens position P _an (n = 1 to 5) at which imaging data acquisition starts and the lens position P _bn (n = 1 to 5) at which imaging data acquisition ends. Adjust as follows.

Note that a reference lens driving speed (for example, the lens position P _f2 corresponding to the second field in FIG. 5A) is set in advance and the lens driving speed is delayed (third to third). when) position _{P f3,} P _f4, P _f5 corresponding lens 5 fields, sends a movement command to delay the timing of transmitting the movement command to move the position of the lens from the second holding position P _h2 The timings T _a3 , T _a4 , and T _a5 may be adjusted.

In addition, when the lens driving speed becomes faster than the reference lens driving speed (at the lens position P _f1 corresponding to the first field), a movement command for moving the lens position from the second holding position _Ph 2 is transmitted. The timing T _a1 for transmitting the movement command may be adjusted so as to be faster than the timing.

  As described above, the control unit can read and predict the lens driving speed of the actuator corresponding to the position of each lens from the table, with respect to the lens position shift accompanying the change in the lens driving speed. The control means can adjust the timing at which the lens is moved from the holding position based on the predicted value. Therefore, the control means can maintain the field for acquiring the imaging data at a constant interval while setting the field for acquiring the imaging data at a predetermined interval.

In the autofocus device 19 according to the above embodiment, the lens positions P _{an to} P _bn calculated as the lens position P _fn having the maximum focus evaluation value from the imaging data of all the fields acquired by the control unit 18 are the final lens positions. Any position of the lens positions P _{an to} P _bn may be set as the target position, and specifically, approximately the middle position ((P _bn −P _an ) / 2) of the range in which the imaging data is acquired. May be the target position.

  In the autofocus device 19 according to the above-described embodiment, the target position where the focus evaluation value is maximized is calculated from the imaging data acquired from the field provided in the focus area, and the lens is moved to the target position. It is not limited to this. For example, the control means calculates an area including the target position among the fields from the acquired imaging data of each field, and subdivides the area to acquire the imaging data again for each of the plurality of small fields provided. Accordingly, the target position may be calculated from the acquired imaging data of each small field by moving the lens stepwise from the position corresponding to the first small field. At this time, it is preferable that the control device holds the lens in a region corresponding to each small field and acquires imaging data.

  As described above, as a first step, an area including the target position among the fields is calculated from the acquired image data of each small field. Then, as a second step, for each small field provided by subdividing the area, the lens is moved stepwise from the position corresponding to the first small field, and imaging data is acquired for each small field. Thereafter, the target position is calculated from the acquired imaging data of each small field.

  Therefore, when calculating the target position from the imaging data of each field, which is the first step, for example, in order to accurately calculate the target position, each field needs to be further subdivided. In addition, there is a problem that each field cannot be subdivided and cannot be calculated accurately in order to calculate the target position quickly. Since the calculation is performed, the target position can be calculated accurately and quickly.

  In the autofocus device 19 according to the above-described embodiment, the example in which the control unit 18 acquires the imaging data from the imaging element 14 while moving the lenses 13 and 13 in the optical axis direction has been described, but the present invention is not limited thereto. It is not something. For example, when the control unit 18 determines that the light amount is satisfied from the photographing conditions acquired from the image sensor or the light amount sensor, the control unit 18 captures the image data while moving the lens in a certain direction. If it is determined that the amount of light is insufficient (such as shooting at night), the image data is collected after the lens is converged and held at the position corresponding to the field as in a conventional imaging device. May be controlled to be acquired from the image sensor.

  As described above, when the control unit determines that the light amount is insufficient by the image sensor or the light amount sensor, the imaging data when the lens position converges at a position corresponding to each field in order to give priority to securing the light amount. If it is determined that the amount of light is sufficient, the imaging data can be acquired while the lens is moving so as to increase the processing speed of autofocus.

  In the autofocus device 19 according to the above-described embodiment, the control unit 18 is configured such that the direction in which the lenses 13 and 13 are moved stepwise from the first holding position is the direction in which the lenses 13 and 13 are moved as the actuator 16 contracts. Although an example of controlling so as to be described has been described, the present invention is not limited to this. The control means may control so that the direction in which the lenses 13 and 13 are moved stepwise from the first holding position becomes the direction in which the lenses 13 and 13 are moved when the actuator 16 extends.

  In the autofocus device 19 according to the above-described embodiment, the example using the shape memory alloy (SMA, Shape memory alloy) method as the actuator 16 has been described. However, the present invention is not limited to this. For example, the actuator may be an electromagnetic drive system (VCM, Voice Coil Motor), a piezo (piezoelectric element) system, a stepping motor system, or the like.

  In the autofocus device 19 according to the above-described embodiment, the extension amount of the lens for each field provided in the focus area is set so as to overlap with the extension amount of other lenses, and is set so that the depth of field overlaps. It may be. In this way, it is possible to prevent the optimal focus evaluation value from leaking to the imaging data acquired from each field, and the target position can be calculated accurately.

  In the autofocus device 19 according to the above embodiment, the example in which the actuator 16 is cooled by natural heat dissipation has been described, but the present invention is not limited to this. The imaging device may further include a cooling mechanism for cooling the shape memory alloy, or may be forcibly cooled. For example, the cooling mechanism may be air cooling or water cooling, or may be a Peltier element. Thus, the cooling rate of the shape memory alloy can be increased by forcibly cooling the shape memory alloy using the cooling mechanism.

  An autofocus device according to the present invention, an imaging device equipped with the autofocus device, and a portable electronic device equipped with the imaging device constitute a digital camera, a mobile phone with a camera function, a personal digital assistant (PDA), and the like It can be used effectively as something to do.

DESCRIPTION OF SYMBOLS 1 Portable electronic device 2 Imaging device 13 Lens 14 Image pick-up element 16 Actuator 17 Driving means 18 Control means 19 Autofocus device

Claims (4)

A lens that can move in a region corresponding to the focus region, an image sensor that receives light through the lens, an actuator that moves the lens, a driving unit that drives the actuator, and the driving unit that moves the lens controls and a control means for acquiring imaging data, calculates a target position for finally positioning the lens from the imaging data, the pre-Symbol lens controller controls the drive means so as to position to the target position The control means is configured to hold the lens provided in the area corresponding to the focus area while moving the area corresponding to the focus area in a certain direction. The lens is moved stepwise so as to be separated by position, and the lens held at the holding position is The lens is moved from the holding position so that the imaging data is acquired in a field provided until the next holding position is moved and the field for acquiring the imaging data is maintained at a predetermined interval. An autofocus device characterized in that the timing at which image data is acquired can be adjusted while the timing to be performed is set at a predetermined interval. A lens that can move in a region corresponding to the focus region, an image sensor that receives light through the lens, an actuator that moves the lens, a driving unit that drives the actuator, and the driving unit that moves the lens controls and a control means for acquiring imaging data, calculates a target position for finally positioning the lens from the imaging data, the pre-Symbol lens controller controls the drive means so as to position to the target position The control means is configured to hold the lens provided in the area corresponding to the focus area while moving the area corresponding to the focus area in a certain direction. The lens is moved stepwise so as to be separated by position, and the lens held at the holding position is The acquisition timing of the imaging data is determined so that the imaging data is acquired in a field provided until the next holding position is moved and the field for acquiring the imaging data is maintained at a predetermined interval. An autofocus device characterized in that the timing for moving the lens from the holding position can be adjusted while the interval is set. An imaging apparatus comprising the autofocus device according to claim 1. A portable electronic device comprising the imaging device according to claim 3.

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