JP2013064817A - Lens barrel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lens barrel capable of shortening time required to detect a focus condition of an optical system.SOLUTION: A lens barrel comprises: an optical system which has a focus adjustment optical system 32; a drive section 36 which drives the focus adjustment optical system 32 in an optical axis direction; a reception section which receives, from a camera body, a drive signal to drive the focus adjustment optical system 32 by either an initial drive system to drive the focus adjustment optical system 32 with a predetermined scan start position as a target stop position, a scan drive system to drive the focus adjustment optical system 32 while detecting a focus condition of the optical system or a focus drive system to drive the focus adjustment optical system 32 with a focus position as the target stop position; and a control section 37 which controls drive of the focus adjustment optical system 32 by the drive section on the basis of the drive signal. The control section 37 differentiates a stop control of the focus adjustment optical system 32 in the initial drive system from the same in the focus drive system.

Description

  The present invention relates to a lens barrel.

  Conventionally, after performing initial drive for driving the focus adjustment optical system to a predetermined scan start position, scan drive for driving the focus adjustment optical system while detecting the focus state of the optical system from the scan start position. Is performed, and when the in-focus position is detected by scan driving, a technique for performing in-focus driving for driving the focus adjustment optical system to the detected in-focus position is known (see, for example, Patent Document 1). ).

JP 2008-310215 A

  However, in the prior art, when the focus adjustment optical system is stopped at the scan start position which is the target stop position in the initial drive, similarly to when the focus adjustment optical system is stopped at the focus position in the focus drive, Since the focus adjustment optical system is driven relatively slowly from a position relatively far from the target stop position and the focus adjustment optical system is stopped at the target stop position, the initial drive takes time. As a result, it may take time to detect the focus state of the optical system.

  The problem to be solved by the present invention is to provide a lens barrel that can shorten the time required to detect the focus state of an optical system.

  The present invention solves the above problems by the following means. In the following description, reference numerals corresponding to the drawings showing the embodiment of the present invention are given and described. However, the reference numerals are only for facilitating the understanding of the invention and are not intended to limit the invention. .

  [1] A lens barrel according to the present invention includes an optical system having a focus adjustment optical system (32), a drive unit (36) for driving the focus adjustment optical system in the optical axis direction, and a predetermined scan start position. Initial drive for driving the focus adjustment optical system as a target stop position, scan drive for driving the focus adjustment optical system while detecting the focus state of the optical system, and the focus position as a target stop position A receiving unit (37) that receives from the camera body (2) a drive signal for causing the focus adjusting optical system to execute driving by any of the focusing methods for driving the focus adjusting optical system; And a control unit (37) for controlling driving of the focus adjustment optical system by the drive unit based on the drive signal, the control unit including stop control of the focus adjustment optical system in the initial drive; And wherein varying the stop control of the focusing optical system in the focus driving.

  [2] In the invention related to the lens barrel, the control unit (37) sets the position at which the focus adjustment optical system (32) is stopped in the initial drive to a position where the focus adjustment optical in the focus drive is started. The focus adjustment optical system can be controlled to be stopped at a position closer to the target stop position as compared with the position at which the system stop operation is started.

  [3] In the invention related to the lens barrel, the control unit (37) determines the speed change rate in the stop operation of the focus adjustment optical system (32) in the initial drive as the focus adjustment optical in the focus drive. It can be configured to perform stop control of the focus adjustment optical system by making it larger than the rate of speed change in the stop operation of the system.

  [4] In the invention related to the lens barrel, when the control unit (37) causes the drive unit (32) to perform the initial drive, the focus adjustment optical system (32) reaches a target stop position. Then, the stop control of the focus adjustment optical system can be performed so as to start the stop operation of the focus adjustment optical system.

  According to the present invention, the time required for the focus state of the optical system can be shortened.

FIG. 1 is a block diagram showing a camera according to the present embodiment. FIG. 2 is a front view showing an imaging surface of the imaging device shown in FIG. FIG. 3 is a front view schematically showing the arrangement of the focus detection pixels 222a and 222b by enlarging the III part of FIG. FIG. 4 is an enlarged front view showing one of the imaging pixels 221. FIG. 5A is an enlarged front view showing one of the focus detection pixels 222a, and FIG. 5B is an enlarged front view showing one of the focus detection pixels 222b. FIG. 6 is an enlarged cross-sectional view showing one of the imaging pixels 221. FIG. 7A is an enlarged cross-sectional view showing one of the focus detection pixels 222a, and FIG. 7B is an enlarged cross-sectional view showing one of the focus detection pixels 222b. 8 is a cross-sectional view taken along line VIII-VIII in FIG. FIG. 9 is a diagram for explaining an example of a focus detection method using a contrast detection method. FIG. 10 is a flowchart showing the operation of the camera according to this embodiment. FIG. 11 is a diagram for explaining stop control of the focus lens in the initial drive and the focus drive. FIG. 12 is a view for explaining stop control of the focus lens in the initial drive and the focus drive.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a main part configuration diagram showing a digital camera 1 according to an embodiment of the present invention. A digital camera 1 according to the present embodiment (hereinafter simply referred to as a camera 1) includes a camera body 2 and a lens barrel 3, and the camera body 2 and the lens barrel 3 are detachably coupled by a mount unit 4. Yes.

  The lens barrel 3 is an interchangeable lens that can be attached to and detached from the camera body 2. As shown in FIG. 1, the lens barrel 3 includes a photographic optical system including lenses 31, 32, 33 and a diaphragm 34.

  The lens 32 is a focus lens, and can adjust the focal length of the photographing optical system by moving in the direction of the optical axis L1. The focus lens 32 is provided so as to be movable along the optical axis L1 of the lens barrel 3, and its position is adjusted by the focus lens drive motor 36 while its position is detected by the encoder 35.

  The specific configuration of the moving mechanism along the optical axis L1 of the focus lens 32 is not particularly limited. For example, a rotating cylinder is rotatably inserted into a fixed cylinder fixed to the lens barrel 3, a helicoid groove (spiral groove) is formed on the inner peripheral surface of the rotating cylinder, and the focus lens 32 is fixed. The end of the lens frame is fitted into the helicoid groove. Then, by rotating the rotating cylinder by the focus lens drive motor 36, the focus lens 32 fixed to the lens frame moves straight along the optical axis L1.

  As described above, the focus lens 32 fixed to the lens frame by rotating the rotary cylinder with respect to the lens barrel 3 moves straight in the direction of the optical axis L1, but the focus lens drive motor 36 as the drive source is the lens. The lens barrel 3 is provided. The focus lens drive motor 36 and the rotary cylinder are connected by a transmission composed of a plurality of gears, for example, and when the drive shaft of the focus lens drive motor 36 is driven to rotate in any one direction, it is transmitted to the rotary cylinder at a predetermined gear ratio. Then, when the rotating cylinder rotates in any one direction, the focus lens 32 fixed to the lens frame moves linearly in any direction of the optical axis L1. When the drive shaft of the focus lens drive motor 36 is rotated in the reverse direction, the plurality of gears constituting the transmission also rotate in the reverse direction, and the focus lens 32 moves straight in the reverse direction of the optical axis L1. .

  The position of the focus lens 32 is detected by the encoder 35. As described above, the position of the focus lens 32 in the optical axis L1 direction correlates with the rotation angle of the rotating cylinder, and can be obtained by detecting the relative rotation angle of the rotating cylinder with respect to the lens barrel 3, for example.

  As the encoder 35 of this embodiment, an encoder that detects the rotation of a rotating disk coupled to the rotational drive of the rotating cylinder with an optical sensor such as a photo interrupter and outputs a pulse signal corresponding to the number of rotations, or a fixed cylinder And the contact point of the brush on the surface of the flexible printed wiring board provided on either one of the rotating cylinders, and the brush contact provided on the other, the amount of movement of the rotating cylinder (in either the rotational direction or the optical axis direction) A device that detects a change in the contact position according to the detection circuit using a detection circuit can be used.

  The focus lens 32 can move in the direction of the optical axis L1 from the end on the camera body side (also referred to as the closest end) to the end on the subject side (also referred to as the infinite end) by the rotation of the rotating cylinder described above. it can. Incidentally, the current position information of the focus lens 32 detected by the encoder 35 is sent to the camera control unit 21 to be described later via the lens control unit 37, and the focus lens drive motor 36 calculates the focus calculated based on this information. The driving position of the lens 32 is driven by being sent from the camera control unit 21 via the lens control unit 37.

  The diaphragm 34 is configured such that the aperture diameter around the optical axis L1 can be adjusted in order to limit the amount of light flux that passes through the photographing optical system and reaches the image sensor 22 and to adjust the blur amount. The adjustment of the aperture diameter by the diaphragm 34 is performed, for example, by sending an appropriate aperture diameter calculated in the automatic exposure mode from the camera control unit 21 via the lens control unit 37. Further, the set aperture diameter is input from the camera control unit 21 to the lens control unit 37 by a manual operation by the operation unit 28 provided in the camera body 2. The aperture diameter of the aperture 34 is detected by an aperture sensor (not shown), and the lens controller 37 recognizes the current aperture diameter.

  Further, the lens control unit 37 receives a drive signal for driving the focus lens 32 from the camera control unit 21, and performs drive control of the focus lens 32 based on the received drive signal. The drive control of the focus lens 32 by the lens control unit 37 will be described later.

  On the other hand, the camera body 2 is provided with an imaging element 22 that receives the light beam L1 from the photographing optical system on a planned focal plane of the photographing optical system, and a shutter 23 is provided on the front surface thereof. The image sensor 22 is composed of a device such as a CCD or CMOS, converts the received optical signal into an electrical signal, and sends it to the camera control unit 21. The captured image information sent to the camera control unit 21 is sequentially sent to the liquid crystal drive circuit 25 and displayed on the electronic viewfinder (EVF) 26 of the observation optical system, and a release button ( When (not shown) is fully pressed, the photographed image information is recorded in the camera memory 24 which is a recording medium. The camera memory 24 can be either a removable card type memory or a built-in memory. Details of the structure of the image sensor 22 will be described later.

  The camera body 2 is provided with an observation optical system for observing an image picked up by the image pickup device 22. The observation optical system of the present embodiment includes an electronic viewfinder (EVF) 26 composed of a liquid crystal display element, a liquid crystal driving circuit 25 that drives the electronic viewfinder (EVF) 26, and an eyepiece lens 27. The liquid crystal drive circuit 25 reads the captured image information captured by the image sensor 22 and sent to the camera control unit 21, and drives the electronic viewfinder 26 based on the read image information. Thereby, the user can observe the current captured image through the eyepiece lens 27. Note that, instead of or in addition to the observation optical system using the optical axis L2, a liquid crystal display may be provided on the back surface of the camera body 2, and a photographed image may be displayed on the liquid crystal display.

  A camera control unit 21 is provided in the camera body 2. The camera control unit 21 is electrically connected to the lens control unit 37 through an electric signal contact unit 41 provided in the mount unit 4, receives lens information from the lens control unit 37, and defocuses to the lens control unit 37. Send information such as volume and aperture diameter. The camera control unit 21 reads out the pixel output from the image sensor 22 as described above, generates image information by performing predetermined information processing on the read out pixel output as necessary, and generates the generated image information. Is output to the liquid crystal driving circuit 25 and the memory 24 of the electronic viewfinder 26. The camera control unit 21 controls the entire camera 1 such as correction of image information from the image sensor 22 and detection of a focus adjustment state and an aperture adjustment state of the lens barrel 3.

  In addition to the above, the camera control unit 21 detects the focus state of the photographic optical system by the phase detection method and the focus state of the photographic optical system by the contrast detection method based on the pixel data read from the image sensor 22. I do. A specific focus state detection method will be described later.

  The operation unit 28 is an input switch for a photographer to set various operation modes of the camera 1, such as a shutter release button, and can switch between an auto focus mode and a manual focus mode. Various modes set by the operation unit 28 are sent to the camera control unit 21, and the operation of the entire camera 1 is controlled by the camera control unit 21. The shutter release button includes a first switch SW1 that is turned on when the button is half-pressed and a second switch SW2 that is turned on when the button is fully pressed.

  Next, the image sensor 22 according to the present embodiment will be described.

  FIG. 2 is a front view showing the imaging surface of the imaging device 22, and FIG. 3 is a front view schematically showing the arrangement of the focus detection pixels 222a and 222b by enlarging the III part of FIG.

  As shown in FIG. 3, the imaging element 22 of the present embodiment includes a green pixel G having a color filter in which a plurality of imaging pixels 221 are two-dimensionally arranged on the plane of the imaging surface and transmit a green wavelength region. A red pixel R having a color filter that transmits a red wavelength region and a blue pixel B having a color filter that transmits a blue wavelength region are arranged in a so-called Bayer Arrangement. That is, in four adjacent pixel groups 223 (dense square lattice arrangement), two green pixels are arranged on one diagonal line, and one red pixel and one blue pixel are arranged on the other diagonal line. The image sensor 22 is configured by repeatedly arranging the pixel group 223 on the imaging surface of the image sensor 22 in a two-dimensional manner with the Bayer array pixel group 223 as a unit.

  The unit pixel group 223 may be arranged in a dense hexagonal lattice arrangement other than the dense square lattice shown in the figure. Further, the configuration and arrangement of the color filters are not limited to this, and an arrangement of complementary color filters (green: G, yellow: Ye, magenta: Mg, cyan: Cy) can also be adopted.

  FIG. 4 is an enlarged front view showing one of the imaging pixels 221, and FIG. 6 is a cross-sectional view. One imaging pixel 221 includes a micro lens 2211, a photoelectric conversion unit 2212, and a color filter (not shown), and a photoelectric conversion unit is formed on the surface of the semiconductor circuit substrate 2213 of the image sensor 22 as shown in the cross-sectional view of FIG. 2212 is built in and a microlens 2211 is formed on the surface. The photoelectric conversion unit 2212 is configured to receive an imaging light beam that passes through an exit pupil (for example, F1.0) of the photographing optical system by the micro lens 2211, and receives the imaging light beam.

  In addition, focus detection pixel rows 22a, 22b, and 22c in which focus detection pixels 222a and 222b are arranged in place of the above-described imaging pixels 221 at the center of the image pickup surface of the image pickup element 22 and three positions that are symmetrical from the center. Is provided. As shown in FIG. 3, one focus detection pixel column includes a plurality of focus detection pixels 222 a and 222 b that are alternately arranged adjacent to each other in a horizontal row (22 a, 22 c, 22 c). Yes. In the present embodiment, the focus detection pixels 222a and 222b are densely arranged without providing a gap at the position of the green pixel G and the blue pixel B of the image pickup pixel 221 arranged in the Bayer array.

  Note that the positions of the focus detection pixel rows 22a to 22c shown in FIG. 2 are not limited to the illustrated positions, and may be any one or two, or may be arranged at four or more positions. it can. In actual focus detection, a photographer manually operates the operation unit 28 from among a plurality of focus detection pixel rows 22a to 22c, and selects a desired focus detection pixel row as a focus detection area. You can also.

  FIG. 5A is an enlarged front view showing one of the focus detection pixels 222a, and FIG. 7A is a cross-sectional view of the focus detection pixel 222a. FIG. 5B is an enlarged front view showing one of the focus detection pixels 222b, and FIG. 7B is a cross-sectional view of the focus detection pixel 222b. As shown in FIG. 5A, the focus detection pixel 222a includes a micro lens 2221a and a semicircular photoelectric conversion unit 2222a. As shown in the cross-sectional view of FIG. A photoelectric conversion portion 2222a is formed on the surface of the semiconductor circuit substrate 2213, and a micro lens 2221a is formed on the surface. The focus detection pixel 222b includes a micro lens 2221b and a photoelectric conversion unit 2222b as shown in FIG. 5B, and a semiconductor of the image sensor 22 as shown in a cross-sectional view of FIG. 7B. A photoelectric conversion unit 2222b is formed on the surface of the circuit board 2213, and a microlens 2221b is formed on the surface. Then, as shown in FIG. 3, these focus detection pixels 222a and 222b are alternately arranged adjacent to each other in a horizontal row, thereby forming focus detection pixel rows 22a to 22c shown in FIG.

  The photoelectric conversion units 2222a and 2222b of the focus detection pixels 222a and 222b have such a shape that the microlenses 2221a and 2221b receive a light beam that passes through a predetermined region (eg, F2.8) of the exit pupil of the photographing optical system. Is done. Further, the focus detection pixels 222a and 222b are not provided with color filters, and their spectral characteristics are the total of the spectral characteristics of a photodiode that performs photoelectric conversion and the spectral characteristics of an infrared cut filter (not shown). ing. However, it may be configured to include one of the same color filters as the imaging pixel 221, for example, a green filter.

  In addition, although the photoelectric conversion units 2222a and 2222b of the focus detection pixels 222a and 222b illustrated in FIGS. 5A and 5B have a semicircular shape, the shapes of the photoelectric conversion units 2222a and 2222b are not limited thereto. Other shapes such as an elliptical shape, a rectangular shape, and a polygonal shape can also be used.

  Here, a so-called phase difference detection method for detecting the focus state of the photographing optical system based on the pixel outputs of the focus detection pixels 222a and 222b described above will be described.

  FIG. 8 is a cross-sectional view taken along the line VIII-VIII in FIG. 3. The focus detection pixels 222 a-1, 222 b-1, 222 a-2, and 222 b-2 that are arranged in the vicinity of the photographing optical axis L 1 and adjacent to each other are It shows that light beams AB1-1, AB2-1, AB1-2, and AB2-2 irradiated from the distance measuring pupils 351 and 352 of the exit pupil 350 are received. 8 illustrates only the focus detection pixels 222a and 222b that are located in the vicinity of the photographing optical axis L1, but other focus detection pixels other than the focus detection pixels illustrated in FIG. 8 are illustrated. In the same manner, the light beams emitted from the pair of distance measuring pupils 351 and 352 are respectively received.

  Here, the exit pupil 350 is an image set at a distance D in front of the microlenses 2221a and 2221b of the focus detection pixels 222a and 222b arranged on the planned focal plane of the photographing optical system. The distance D is a value uniquely determined according to the curvature and refractive index of the microlens, the distance between the microlens and the photoelectric conversion unit, and the distance D is referred to as a distance measurement pupil distance. The distance measurement pupils 351 and 352 are images of the photoelectric conversion units 2222a and 2222b respectively projected by the micro lenses 2221a and 2221b of the focus detection pixels 222a and 222b.

  In FIG. 8, the arrangement direction of the focus detection pixels 222a-1, 222b-1, 222a-2, 222b-2 coincides with the arrangement direction of the pair of distance measuring pupils 351, 352.

  As shown in FIG. 8, the microlenses 2221a-1, 2221b-1, 2221a-2, and 2221b-2 of the focus detection pixels 222a-1, 222b-1, 222a-2, and 222b-2 are photographic optical systems. Near the planned focal plane. The shapes of the photoelectric conversion units 2222a-1, 2222b-1, 2222a-2, 2222b-2 arranged behind the micro lenses 2221a-1, 2221b-1, 2221a-2, 2221b-2 are the same as the micro lenses 2221a-1, 2221b-1, 2221a-2, 2221b-2. Projected onto the exit pupil 350 that is separated from the lenses 2221 a-1, 2221 b-1, 2221 a-2, and 2221 b-2 by a distance measurement distance D, and the projection shape forms distance measurement pupils 351 and 352.

  That is, the microlens and the photoelectric conversion unit in each focus detection pixel so that the projection shapes (distance measurement pupils 351 and 352) of the focus detection pixels coincide on the exit pupil 350 at the distance D. Is determined, and the projection direction of the photoelectric conversion unit in each focus detection pixel is thereby determined.

  As shown in FIG. 8, the photoelectric conversion unit 2222a-1 of the focus detection pixel 222a-1 is formed on the microlens 2221a-1 by the light beam AB1-1 that passes through the distance measuring pupil 351 and goes to the microlens 2221a-1. A signal corresponding to the intensity of the image to be output is output. Similarly, the photoelectric conversion unit 2222a-2 of the focus detection pixel 222a-2 passes through the distance measuring pupil 351, and the intensity of the image formed on the microlens 2221a-2 by the light beam AB1-2 toward the microlens 2221a-2. The signal corresponding to is output.

  Further, the photoelectric conversion unit 2222b-1 of the focus detection pixel 222b-1 passes through the distance measuring pupil 352, and the intensity of the image formed on the microlens 2221b-1 by the light beam AB2-1 directed to the microlens 2221b-1. Output the corresponding signal. Similarly, the photoelectric conversion unit 2222b-2 of the focus detection pixel 222b-2 passes through the distance measuring pupil 352, and the intensity of the image formed on the microlens 2221b-2 by the light beam AB2-2 toward the microlens 2221b-2. The signal corresponding to is output.

  Then, a plurality of the above-described two types of focus detection pixels 222a and 222b are arranged in a straight line as shown in FIG. 3, and the outputs of the photoelectric conversion units 2222a and 2222b of the focus detection pixels 222a and 222b are used as the distance measurement pupil 351. Of the pair of images formed on the focus detection pixel array by the focus detection light fluxes passing through each of the distance measurement pupil 351 and the distance measurement pupil 352. Data on the distribution is obtained. Then, by applying an image shift detection calculation process such as a correlation calculation process or a phase difference detection process to the intensity distribution data, an image shift amount by a so-called phase difference detection method can be detected.

  Then, a conversion calculation is performed on the obtained image shift amount according to the center-of-gravity interval of the pair of distance measuring pupils, thereby obtaining a focal plane corresponding to the current focal plane (the position corresponding to the position of the microlens array on the planned focal plane). The deviation of the focal plane in the detection area), that is, the defocus amount can be obtained.

  The calculation of the image shift amount by the phase difference detection method and the calculation of the defocus amount based thereon are executed by the camera control unit 21.

  Further, the camera control unit 21 reads the output of the imaging pixel 221 of the imaging element 22 and calculates a focus evaluation value based on the read pixel output. This focus evaluation value can be obtained, for example, by extracting a high-frequency component of an image output from the imaging pixel 221 of the imaging element 22 using a high-frequency transmission filter. It can also be obtained by extracting high-frequency components using two high-frequency transmission filters having different cutoff frequencies.

  Then, the camera control unit 21 sends a drive signal to the lens control unit 37 to drive the focus lens 32 at a predetermined sampling interval (distance) to obtain a focus evaluation value at each position, and the focus evaluation value is the maximum. The focus detection by the contrast detection method is performed in which the position of the focus lens 32 is determined as the in-focus position. Note that this in-focus position is obtained when, for example, when the focus evaluation value is calculated while driving the focus lens 32, the focus evaluation value rises twice and then moves down twice. Can be obtained by performing an operation such as interpolation using the focus evaluation value.

  Here, FIG. 9 is a diagram for explaining an example of a focus detection method using a contrast detection method. In the example shown in FIG. 9, the focus lens 32 is located at P0 shown in FIG. 9. First, the focus lens 32 is driven from P0 to a predetermined scan start position (position P1 in FIG. 9). Initial drive is performed. Then, the focus lens 32 is driven from the scan start position (position P1 in FIG. 9) from the infinity side to the close side, and the focus evaluation value is acquired by the contrast detection method at a predetermined interval. Driving is performed. When the focus lens 32 is moved to the position P2 shown in FIG. 9, the peak position of the focus evaluation value (position P3 in FIG. 9) is detected as the focus position, and the detected focus position is detected. Focusing driving for driving the focus lens 32 is performed up to (position P3 in FIG. 9).

  Next, an operation example of the camera 1 according to the present embodiment will be described. FIG. 10 is a flowchart showing the operation of the camera 1 according to this embodiment.

  First, in step S101, generation of a through image by the camera control unit 21 and display of a through image by the electronic viewfinder 26 of the observation optical system are started. Specifically, the camera control unit 21 reads the output of the image sensor 22 and generates a through image based on the read image signal. The through image generated by the camera control unit 21 is sent to the liquid crystal drive circuit 25 and displayed on the electronic viewfinder 26 of the observation optical system. Thus, the user can visually recognize the subject image via the eyepiece lens 27. Note that the generation of the through image and the display of the through image are repeatedly executed at predetermined intervals.

  In step S102, the camera control unit 21 determines whether or not the shutter release button provided in the operation unit 28 is half-pressed (the first switch SW1 is turned on). When the first switch SW1 is turned on, the process proceeds to step S103. On the other hand, when the first switch SW1 is not turned on, the process returns to step S101, and the first switch SW1 is turned on at a predetermined interval until the first switch SW1 is turned on. The image is displayed repeatedly.

  When the shutter release button is half-pressed, the process proceeds to step S103, and the initial drive of the focus lens 32 is started in step S103. Specifically, a drive signal for starting the initial drive is transmitted from the camera control unit 21 to the lens control unit 37, and the focus lens 32 is moved by the focus lens drive motor 36 via the lens control unit 37. Initial drive for driving to a predetermined scan start position is started. The scan start position is not particularly limited. For example, when a focus position exists in the vicinity of the current lens position of the focus lens 32, the focus position is detected with the minimum number of focus evaluation values. The position at which scanning can be performed can be set as the scanning start position. In addition, for example, a close end, an infinite end, or a position determined by a shooting scene can be set as a scan start position.

When the initial drive is started in step S103, the process proceeds to step S104. In step S104, the lens control unit 37 determines whether or not the focus lens 32 has reached the stop control start position _Pst1 in the initial drive. Is done. Here, the stop control start position _Pst1 is a lens position at which stop control for stopping the drive of the focus lens 32 is started in the initial drive, and in this embodiment, in order to shorten the time required for the initial drive. In addition, it is set to a position closer to the target stop position than the stop control start position _Pst2 in focusing drive described later. Focusing lens 32, if it is determined not to have reached the stop control start position P _st1 is while waiting at step S104, the focus lens 32 is a determination whether the host vehicle has reached the stop control start position P _st1 When it is repeatedly performed and it is determined that the focus lens 32 has reached the stop control start position _Pst1 , the process proceeds to step S105, and the lens control unit 37 starts stop control for stopping the drive of the focus lens 32. The

  Here, FIG. 11 is a graph for explaining stop control of the focus lens 32 in the initial drive and the focus drive. The horizontal axis represents time, and the vertical axis represents the lens position of the focus lens 32 at the start of driving. The displacement amount of the lens position of the focus lens 32 when 0 is shown is shown.

For example, as shown in FIG. 11, in the initial drive, when the focus lens 32 is driven from the current lens position P ₀ to the scan start position that is the target stop position P _trg , the lens control unit 37 includes the focus lens 32. Is driven from the current lens position P ₀ toward the scan start position that is the target stop position P _trg , it is determined whether or not the focus lens 32 has reached the stop control start position P _st1 in the initial drive ( Step S104). In the example shown in FIG. 11, since the focus lens 32 reaches the stop control start position _Pst1 in the initial drive at time t2, stop control of the focus lens 32 is started from time t2 (step S105). As a result, the driving speed of the focus lens 32 is gradually reduced, and the focus lens 32 stops at the scan start position that is the target stop position P _trg at time t3.

  In step S106, the camera control unit 21 determines whether or not the focus lens 32 has been stopped by the stop control of the focus lens 32. If the focus lens 32 is still driven, the focus control is performed. The process waits in step S106 until the lens 32 stops, and if the focus lens 32 stops, the process proceeds to step S107 to perform scan driving.

  In step S107, since the initial drive is completed, scan drive for driving the focus lens 32 is started while detecting the focus state of the optical system. Specifically, a drive signal for performing scan drive is transmitted from the camera control unit 21 to the lens control unit 37, and the focus lens drive motor 36 scans the focus lens 32 via the lens control unit 37. Is started. Further, the camera control unit 21 reads the image signal from the imaging pixel 221 of the imaging element 22 at predetermined intervals while driving the focus lens 32 to scan, and repeatedly calculates the focus evaluation value based on the read image signal. Based on the calculated plurality of focus evaluation values, focus detection is performed by a contrast detection method in which a lens position where the focus evaluation value reaches a peak is detected as a focus position.

  In step S108, the camera control unit 21 determines whether or not the in-focus position has been detected by scan driving. If the in-focus position can be detected, in order to perform in-focus driving, The process proceeds to step S112. On the other hand, if the in-focus position cannot be detected, the process proceeds to step S109.

  In step S <b> 109, the camera control unit 21 determines whether the scan drive has been performed for the entire driveable range of the focus lens 32. If scan drive is not performed for the entire driveable range of the focus lens 32, the process returns to step S108, and the process of detecting the in-focus position by the contrast detection method is continued while the focus lens 32 is scan-driven. Done. On the other hand, if the scan drive has been completed for the entire driveable range of the focus lens 32, it is determined that distance measurement is impossible, and the process proceeds to step S110. After the scan drive is completed, the scan is completed in step S111. Unfocusable display is performed. Note that the in-focus state display is performed by the electronic viewfinder 26, for example.

  On the other hand, if it is determined in step S108 that the in-focus position has been detected, the process proceeds to step S112. In step S112, in-focus driving for driving the focus lens 32 to the in-focus position is started. Specifically, a drive signal for starting focus drive is transmitted from the camera control unit 21 to the lens control unit 37, and the focus lens 32 is driven by the focus lens drive motor 36 via the lens control unit 37. Focusing driving for driving to the in-focus position is started.

In step S113, the lens control unit 37 determines whether or not the focus lens 32 has reached the stop control start position _Pst2 in the focusing drive. Here, the stop control start position P _st2, in focus driving, a lens position to start the stop control for stopping the driving of the focus lens 32, the stop control of the focus lens 32 from the stop control start position P _st2 When started, the focus lens 32 can be set to a position where it can be accurately stopped at the in-focus position.

In step S113, whether the focus lens 32, if it is determined not to have reached the stop control start position P _st2, hold and waits in step S113, the focus lens 32 has reached the stop control start position P _st2 whether Is repeatedly performed, and when it is determined that the focus lens 32 has reached the stop control start position _Pst2 , the process proceeds to step S114, and the lens controller 37 stops the drive of the focus lens 32 to stop. Control begins.

For example, as shown in FIG. 11, in the focus drive, when the focus lens 32 is driven from the current lens position P ₀ to the focus position that is the target stop position P _trg , the lens control unit 37 includes the focus lens. While driving the lens 32 toward the in-focus position that is the target stop position P _trg, it is determined whether or not the focus lens 32 has reached the stop control start position P _st2 in the in-focus drive (step S113). In the example shown in FIG. 11, since the focus lens 32 reaches the stop control start position _Pst2 in focus drive at time t1, stop control of the focus lens 32 is started from time t1 (step S114). As a result, the drive speed of the focus lens 32 is gradually reduced, and the focus lens 32 stops at the in-focus position, which is the target stop position P _trg , at time t4.

Thus, in this embodiment, the stop control of the focus lens 32 in the initial drive and the stop control of the focus lens 32 in the focus drive are performed in different modes. That is, as shown in FIG. 11, in the initial drive, priority is given to shortening the time required for the initial drive, and stop control closer to the target stop position P _trg than the stop control start position P _st2 in the focus drive. At the start position _Pst1 , stop control of the focus lens 32 is started. In the initial drive, the stop control of the focus lens 32 so that the speed change rate of the drive speed of the focus lens 32 by the stop control of the focus lens 32 is larger than the speed change rate of the drive speed in the focus drive. Is done. That is, in the initial drive, in order to shorten the time required for the initial drive, the focus lens 32 is driven at a high speed without decelerating until the focus lens 32 is close to the target stop position P _trg. When the lens 32 is close to the target stop position P _trg , the focus lens 32 is rapidly decelerated and the focus lens 32 is stopped.

On the other hand, in the focus drive, priority is given to driving the focus lens 32 accurately to the focus position, as shown in FIG. 11, the stop control start position prior to the stop control start position _Pst1 in the initial drive. From _Pst2 , stop control of the focus lens 32 is started. In focus drive, the focus lens 32 is controlled to stop by setting the speed change rate of the focus lens 32 to be smaller than the speed change rate of the drive speed in the initial drive. That is, in the stop control of the focus lens 32 in the focus drive, the stop control of the focus lens 32 is started at a timing earlier than the initial drive in order to accurately drive the focus lens 32 to the in-focus position. The focus lens 32 is driven to the in-focus position over time.

  In step S115, the camera control unit 21 determines whether or not the focus lens 32 has been stopped by the stop control of the focus lens 32. If the focus lens 32 is still driven, the focus control is performed. The process waits in step S115 until the lens 32 stops, and if the focus lens 32 stops, the process proceeds to step S116, and a focus display is performed. The in-focus display is performed by the electronic viewfinder 26, for example. Further, when performing the focus display, a display for notifying the user that the focus operation has been performed may be performed together.

  As described above, the operation of the camera 1 according to the present embodiment is executed.

Thus, in the present embodiment, in the initial drive, as shown in FIG. 11, the stop control start position P _st1 in the initial drive is compared with the stop control start position P _st2 in the focus drive. Stop control of the focus lens 32 is started so that the position is close to P _trg . In the initial drive, stop control of the focus lens 32 is performed so that the speed change rate in the stop operation of the focus lens 32 is larger than the speed change rate in the stop operation of the focus lens 32 in the focus drive. Thus, in the initial drive, the focus lens 32 is driven at a higher speed without decelerating until the focus lens 32 reaches the target stop position P _trg , compared with the focus drive. Since the focus lens 32 can be rapidly decelerated after 32 _{approaches the} target stop position P _trg , the stop control of the focus lens 32 in the initial drive is the same as the stop control of the focus lens 32 in the focus drive. Compared with the method, the time required for initial driving can be shortened, and as a result, the time required for focus detection can be shortened.

In the present embodiment, in the focus drive, the stop control of the focus lens 32 is started from the stop control start position P _st2 far from the target stop position P _trg compared to the stop control start position P _st1 in the initial drive. Further, stop control of the focus lens 32 is performed so that the speed change rate of the drive speed of the focus lens 32 is smaller than the speed change rate of the drive speed in the initial drive. Thereby, in the focus drive, the focus lens 32 can be driven to the focus position more accurately than in the initial drive, and as a result, an image focused on the subject can be appropriately captured. .

Further, in the present embodiment, the lens control unit 37 independently determines whether or not to start the stop control of the focus lens 32, and starts the stop control of the focus lens 32. The stop control of the focus lens 32 according to the lens position of the focus lens 32 compared to the case where the control signal from the control unit 21 is received and the stop control of the focus lens 32 is started based on the received control signal. Thus, in the stop control of the focus lens 32, it is possible to effectively prevent the focus lens 32 from being greatly separated from the target stop position P _trg .

  The embodiment described above is described for facilitating the understanding of the present invention, and is not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

For example, in the above-described embodiment, as shown in FIG. 11, the stop control start position P _st1 in the initial drive is compared with the stop control start position P _st2 in the focus drive, and is closer to the target stop position P _trg. so that, although illustrating the configuration for performing stop control of the focus lens 32 is not limited to this configuration, for example, as shown in FIG. 12, the stop control start position P _st1 in the initial driving the target stop position P _trg The focus lens 32 may be set to stop driving after the focus lens 32 reaches the target stop position P _trg . For example, in the example shown in FIG. 12, the focus lens 32 is driven to the target stop position P _trg without decelerating the drive speed of the focus lens 32 until time t5, and at time t5, the focus lens 32 is in the initial drive. By starting stop control of the focus lens 32 after reaching the stop control start position P _st1 (= target stop position P _trg ) (step S105), the focus lens 32 stops at time t6.

  The camera 1 of the embodiment described above is not particularly limited, and the present invention may be applied to other optical devices such as a digital video camera, a lens-integrated digital camera, and a camera for a mobile phone.

DESCRIPTION OF SYMBOLS 1 ... Digital camera 2 ... Camera body 21 ... Camera control part 22 ... Imaging device 221 ... Imaging pixel 222a, 222b ... Focus detection pixel 3 ... Lens barrel 32 ... Focus lens 36 ... Focus lens drive motor 37 ... Lens control part

Claims (4)

An optical system having a focusing optical system;
A drive unit for driving the focus adjustment optical system in the optical axis direction;
Initial drive for driving the focus adjustment optical system with a predetermined scan start position as a target stop position, scan drive for driving the focus adjustment optical system while detecting the focus state of the optical system, and a focus position A receiver for receiving, from the camera body, a drive signal for causing the focus adjustment optical system to perform drive by any of the focusing methods for driving the focus adjustment optical system with the target stop position as a target stop position;
A control unit that controls driving of the focus adjustment optical system by the driving unit based on the driving signal;
The lens barrel is characterized in that the control unit makes different the stop control of the focus adjustment optical system in the initial drive and the stop control of the focus adjustment optical system in the focus drive. The lens barrel according to claim 1,
The control unit is close to a target stop position by comparing a position at which the focus adjustment optical system is stopped in the initial drive with a position at which the focus adjustment optical system is stopped in the focus drive. A lens barrel that performs stop control of the focus adjustment optical system as a position. The lens barrel according to claim 1 or 2,
The control unit increases the speed change rate in the stop operation of the focus adjustment optical system in the initial drive to be larger than the speed change rate in the stop operation of the focus adjustment optical system in the focus drive. A lens barrel characterized by performing stop control of the system. In the lens barrel according to any one of claims 1 to 3,
When the control unit causes the driving unit to perform the initial drive, the focus adjustment optical system starts the stop operation of the focus adjustment optical system after the focus adjustment optical system reaches a target stop position. The lens barrel characterized by performing stop control of the optical system.

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