JP2007057974A - Photographing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photographing device capable of shortening time required for AF processing at a low cost. <P>SOLUTION: A previous photometric value X and a previous focusing position G are stored in a RAM 42. When a shutter button 28 is half-depressed, the previous photometric value X, a photometric value Y obtained this time by performing photometry by an AE detection part 61 and the previous focusing position are input in a search range setting part 63. A photometric value decision part 63a which compares the photometric value X with the photometric value Y and decides whether or not the variation is within tolerance is provided in the search range setting part 63. When deciding that the variation is not within the tolerance, the search range setting part 63 sets a search range to an entire area search range, and when deciding that it is within the tolerance, the search range setting part 63 sets it to a narrow area search range narrower than the entire area search and including the previous focusing position. A CPU 40 performs focus adjustment processing of a photographic lens 13 by moving a focus lens 45 on the basis of the search range set by the search range setting part 63. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a photographing apparatus that performs focus adjustment of a photographing lens by a contrast method based on image data picked up by a solid-state image sensor.

  2. Description of the Related Art In recent years, digital cameras, which are photographing devices that store image data obtained by digitally converting an image signal obtained by an image sensor such as a CCD image sensor, in a storage medium such as a memory card, have become popular. In such a digital camera, an automatic focus adjustment process of the taking lens, that is, an autofocus (hereinafter referred to as AF) process is performed by a contrast method.

  In the contrast AF processing described above, imaging is performed while moving the focus lens in the optical axis direction, the integral value of the high frequency component of the image data is calculated as an AF evaluation value, and the position where the AF evaluation value reaches its peak is adjusted. The focus position. For this reason, since the moving range of the focus lens is wide, there is a problem that AF processing takes time.

In order to solve the above-described problem, a distance measuring sensor is provided, and after the focus lens is moved to the vicinity of the in-focus position based on the measurement result of the distance sensor, the focus lens is in a narrow range near the in-focus position. Is known to increase the speed of the AF processing by moving the lens (for example, see Patent Document 1).
JP-A-5-163274

  However, as described in Patent Document 1, when a distance measuring sensor is used, the time required for AF processing can be shortened, but there is a problem that the manufacturing cost increases.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a photographing apparatus capable of reducing the time required for AF processing at a low cost.

    In order to solve the above problem, when the shutter button is operated, the AF evaluation value, which is an integral value of the high-frequency component of the image data captured by the solid-state image sensor, is sequentially moved while moving the focus lens within a predetermined search range. An imaging device that calculates and adjusts the focus of the imaging lens by moving the focus lens to a focus position based on these AF evaluation values, and based on the image data when the shutter button is operated. A photometric means for performing photometry; a photometric value measured by the photometric means; a storage means for storing the in-focus position; a photometric value measured by the photometric means; and a previous photometric value stored in the photometric value storage means The photometric value is compared with the photometric value, the photometric value determining means for determining whether or not the change amount is within the allowable range, and the photometric value determining means, the allowable range. If determined to be outside, the search range is set to the first search range, and if determined to be within the allowable range, the search range is narrower than the first search range and stored in the storage means. Search range setting means for setting a second search range including the in-focus position, and when the shutter button is operated, the search range setting means is controlled to set the search range, and the search range setting means The focus lens is moved within the search range set by the control means to adjust the focus, and the photometric value stored in the storage means and the control means for updating the in-focus position are provided. Is.

  The search range setting means sets the search range to the first search range when the photometric value and the in-focus position are not stored in the storage means, and the control means sets the first search range to the first search range. It is preferable to adjust the focus by moving the focus lens within the search range, and to store the photometric value and the in-focus position in the storage means.

  Furthermore, it is preferable that the control means invalidates the photometric value and the focus position stored in the storage means when an operation button other than the shutter button is operated.

  The photographing lens preferably includes a zoom lens, and the width and position of the first and second search ranges are changed based on the position of the zoom lens.

  The photographing apparatus of the present invention sequentially calculates an AF evaluation value that is an integral value of high-frequency components of image data captured by a solid-state image sensor while moving the focus lens within a predetermined search range when the shutter button is operated. And an imaging device that adjusts the focus of the imaging lens by moving the focus lens to an in-focus position based on these AF evaluation values, calculates the AF evaluation value, and sets the maximum value of the AF evaluation value. An AF detection means for detecting, a maximum value of the AF evaluation value detected by the AF detection means, a storage means for storing the in-focus position, the maximum value detected by the AF detection means, An AF evaluation value determining means that compares the maximum value at the time of the previous focus adjustment stored in the storage means and determines whether or not the change amount is within an allowable range; When the large value and the in-focus position are not stored in the storage unit, the search range is set as the first search range, and when the maximum value and the in-focus position are stored in the storage unit, The second search range is narrower than the first search range and includes the previous in-focus position stored in the storage unit, and the change in the second search range is performed by the AF evaluation value determination unit. When it is determined that the amount is outside the allowable range, search range setting means for setting the search range to the first search range, and when the shutter button is operated, the search range setting means is controlled. The search range is set, and the focus lens is moved within the search range set by the search range setting means to adjust the focus, and stored in the storage means. Said maximum value, and is characterized in that it comprises a control means for updating the focus position.

  The control means preferably invalidates the maximum value and the in-focus position stored in the storage means when an operation button other than the shutter button is operated.

  Furthermore, it is preferable that the photographing lens includes a zoom lens, and the width and position of the first and second search ranges are changed based on the position of the zoom lens.

  The photographing apparatus of the present invention sequentially calculates an AF evaluation value that is an integral value of high-frequency components of image data captured by a solid-state image sensor while moving the focus lens within a predetermined search range when the shutter button is operated. Then, based on these AF evaluation values, the focus lens is moved to an in-focus position to adjust the focus of the photographing lens. The AF evaluation value is calculated, and the maximum AF evaluation value is calculated. Comparing the AF detection means for detecting a value with the maximum value detected by the AF detection means by moving the focus lens in a first search range and a reference value for evaluating the maximum value; AF evaluation value determining means for determining whether or not the maximum value is equal to or greater than the reference value, and a first search range as the search range when the shutter button is operated. A search range that is set to a second search range wider than the first search range when the AF evaluation value determination means determines that the maximum value is not greater than or equal to the reference value. A setting unit; and a control unit configured to control the search range setting unit to set the search range, and to move the focus lens within the search range set by the search range setting unit. Is.

  The second search range is preferably a search range obtained by adding an oversearch amount for absorbing an error due to temperature characteristics of the photographing lens to the first search range.

  Furthermore, it is preferable that the photographing lens includes a zoom lens, and the width and position of the first and second search ranges are changed based on the position of the zoom lens.

  According to the photographing apparatus of the present invention, when the change amount of the photometric value is within the allowable range, the search range of the focus lens is narrower than the first search range, and the second search range including the previous in-focus position, Since focus adjustment is performed by moving the focus lens, it is highly possible that the subject is the same subject when the amount of change in the photometric value is small, so it is possible to adjust the focus within a narrow search range around the in-focus position. As a result, the time required to adjust the focus of the taking lens can be shortened. Further, since expensive parts such as a distance measuring sensor are not required, it can be manufactured at low cost.

  Also, when an operation other than the shutter button is performed, the subject often changes, so the photometric value and the focus position stored in the storage means are automatically invalidated. For this reason, when the subject changes, it is possible to prevent the focus from being adjusted in the second search range, which is a narrow search range including the previous in-focus position.

    According to the photographing apparatus of the present invention, when the maximum value of the AF evaluation value and the focus position at the time of the previous focus adjustment are stored in the storage unit, the second range which is a narrow range including the previous focus position. When the AF search process is performed in the search range, and the maximum AF evaluation value detected in the AF search process is compared with the maximum value of the previous AF evaluation value, and these variations are within the allowable range In addition, the position corresponding to the current maximum value is set as the in-focus position. For this reason, it is possible to shorten the time required for the focus adjustment processing of the photographing lens. Further, since expensive parts such as a distance measuring sensor are not required, it can be manufactured at low cost.

  Further, according to the photographing apparatus of the present invention, when the shutter button is operated, first, the AF search process is performed in the first search range narrower than the second search range, and the AF search process is acquired. When the maximum value of the AF evaluation value is greater than or equal to the reference value, the position corresponding to this maximum value is set as the in-focus position. For this reason, it is possible to shorten the time required for the focus adjustment processing of the photographing lens. Further, since expensive parts such as a distance measuring sensor are not required, it can be manufactured at low cost.

  A digital camera 10 shown in FIGS. 1 and 2 includes a slidable lens barrier 12 on the front surface of a camera body 11, and is slid by user operation. When the lens barrier 12 is moved to the open position (position shown in FIG. 1), the photographing lens 13 and the strobe light emitting unit 14 are exposed to the front surface.

  The lens barrier 12 also serves as a power operation member. When the lens barrier 12 is slid to the open position (position shown in FIG. 1), the power is turned on and the photographing lens 13 and the strobe light emitting unit 14 are shielded. The power is turned off when moved to. Further, a finder objective window 15 constituting an optical finder is provided on the front surface of the camera body 11.

  On the back surface of the camera body 11, an LCD 16, a viewfinder eyepiece window 17 constituting an optical viewfinder, and an operation unit 18 are provided. On the LCD 16, a reproduced image, various setting screens, a through image, and the like are displayed.

  The operation unit 18 includes a mode switch 21, a return button 22, a feed button 23, a zoom button 24, a menu button 25, a cancel button 26, and a display button 27. The mode switch 21 is operated when switching between the shooting mode and the playback mode. The return button 22 and the feed button 23 are pressed when the playback image is fed back and forward in the playback mode.

  The zoom button 24 is pressed in the vertical direction by the user when the zoom lens of the photographing lens 13 is moved in the optical axis direction between the wide end and the tele end to change the optical photographing magnification. The menu button 25 is pressed by the user when displaying the menu screen on the LCD 16.

  The cancel button 26 is pressed to stop various setting operations on the menu screen or return to the previous screen. The display button 27 is pressed by the photographer when the LCD 16 is switched on and off.

  A shutter button 28 is provided on the upper surface of the camera body 11. The shutter button 28 is a two-stage push switch. When the photographer performs framing using the LCD 16 or the optical viewfinder and then lightly presses (half-presses) the shutter button 28, various photographing preparation processes such as exposure adjustment and focus adjustment of the photographing lens 13 are performed. When the shutter button 28 is further pressed from the half-pressed state and is fully pressed, the photographing process is executed.

  A memory card slot 29 and an external output terminal 30 are provided on the side surface of the camera body 11. A memory card 31 as a recording medium on which image data is recorded is detachably loaded in the memory card slot 29. The external output terminal 30 is, for example, a USB terminal, and is used when outputting image data recorded on the memory card 31 to an external device (such as a personal computer).

  Next, the electrical configuration of the digital camera 10 will be described with reference to FIG. The digital camera 10 is provided with a CPU 40 that is a control means for controlling the entire camera. A ROM 41 and a RAM 42 are connected to the CPU 40. The ROM 41 stores control programs and various control data, and the CPU 40 controls each unit in the camera based on these control programs and control data. The work data is temporarily stored in the RAM 42. The RAM 42 is a storage unit that stores the photometric value and the focus position of the focus lens at the previous AE and AF processing.

  Further, the shutter button 28 and the operation unit 18 are connected to the CPU 40. The CPU 40 acquires operation signals from these and executes processing corresponding to each operation signal.

  The photographing lens 13 includes a zoom lens 43, a diaphragm 44, and a focus lens 45. The zoom lens 43 and the focus lens 45 are movable in the optical axis direction. The zoom lens 43 is moved in the optical axis direction by the motor 46, and the focus lens 45 is moved in the optical axis direction by the motor 47. The motor 46 is connected to the CPU 40 via a motor driver 48, and the motor 47 is connected to the CPU 40 via a motor driver 49.

  The CPU 40 controls the motor driver 48 to drive the motor 46 and moves the zoom lens 44 in the optical axis direction to change the optical photographing magnification. Further, the CPU 40 controls the motor driver 49 to drive the motor 47, and moves the focus lens 45 in the optical axis direction to perform focus adjustment.

  The aperture of the diaphragm 44 is changed by the motor 50, and the amount of subject light incident on a CCD image sensor (solid-state imaging device) 52 described later changes. The motor 50 is connected to the CPU 40 via a motor driver 51, and controls the motor driver 51 to drive the motor 50 to adjust the aperture diameter of the diaphragm 44.

  Behind the photographic lens 13, a CCD image sensor 52, which is a solid-state imaging device that images subject light that has passed through the photographic lens 13, is disposed, and a CCD driver 53 is connected to the CCD image sensor 52. . The CCD driver 53 inputs a vertical drive signal and a horizontal drive signal to the CCD image sensor 52 according to the clock pulse input from the timing generator 54 and drives the CCD image sensor 52.

  The timing generator 54 is connected to the CPU 40, and the CPU 40 controls the driving of the CCD image sensor 40 by controlling the timing generator 54 and generating clock pulses.

  The CCD image sensor 52 is connected to a correlated double sampling circuit (CDS) 55 and an AMP 56. As a result, noise removal and amplification are performed on the imaging signal output from the CCD image sensor 52.

  Thereafter, the image pickup signal is converted into image data of a digital signal by the A / D converter 57 and output to the image input controller 58. The image input controller 58 is connected to a frame memory 60 via a data bus 59. The CPU 40 controls the image input controller 58 to store the image data in the frame memory 60.

  In addition to the image input controller 58 and the frame memory 60, the data bus 59 includes a CPU 40, an AE detection unit 61, an AF detection unit 62, a search range setting unit 63, an image signal processing unit 64, a compression / decompression processing unit 65, An LCD driver 66, a media controller 67, and an AF peak determination unit 68 are connected.

  The AE detection unit 61 is a photometric unit that performs photometry based on image data, and outputs a photometric value to the CPU 40. The AE detection unit 61 performs photometry using a center-weighted photometry method in which the luminance value is integrated by increasing the weighting in the central portion of the image, not the average photometry for integrating the luminance value of the entire image. In addition, when the focus lens 45 is moved within a predetermined search range, the AF detection unit 62 integrates high-frequency components of the image data and sequentially calculates an AF evaluation value, and calculates the maximum value of these AF evaluation values. To detect. The AF peak determination unit 68 determines whether or not the maximum AF evaluation value is an AF peak.

  When acquiring the photometric value, the CPU 40 controls the electronic shutter speed of the CCD image sensor 52 and the diaphragm 44 so that the subject light amount incident on the CCD image sensor 52 is optimized based on the photometric value. Further, the CPU 40 controls the AF peak determination unit 68 to determine whether or not the maximum AF evaluation value detected by the AF detection unit 62 is an AF peak. When it is determined that the maximum value of the AF evaluation value is the AF peak, the CPU 40 moves the focus lens 45 to a position corresponding to the maximum value of the AF evaluation value. When it is determined that the maximum AF evaluation value is not the AF peak, the CPU 40 moves the focus lens 45 to the pan focus position.

  When the photometry value X and the focus position are not stored in the RAM 42, the CPU 40 determines the photometry value X detected by the AE detector 61 and the focus position of the focus lens 45 when the shutter button 28 is half-pressed. Is stored in the RAM 42. Next, when the shutter button 28 is half-pressed, the CPU 40 obtains the photometric value Y from the AE detector 61, and obtains the previous photometric value X and in-focus position stored in the RAM 42, and the photometric value Y. Input to the search range setting unit 63.

  As shown in FIG. 4, the search range setting unit 63 includes, as internal parameters, a photometric value change amount allowable value β, a global search start position P, a global search end position Q, a narrow search start position M, and a narrow range. The area search end position N is stored, and as described above, the photometric value X, photometric value Y, and previous focus position are input. Further, the search range setting unit 63 compares the photometric value X with the photometric value Y, and the amount of change (XY) of the photometric value is within the allowable range (−β ≦ X−Y ≦ β). A photometric value determination unit 63a is provided for determining whether or not.

  When the photometric value determination unit 63a determines that the search range setting unit 63 is not within the allowable range (−β ≦ X−Y ≦ β), the search range setting unit 63 sets the entire search range (first search range) shown in FIG. A search range of the focus lens 45 is set, and a global search start position P and a global search end position Q corresponding to the global search are output to the CPU 40. Further, when the photometric value determination unit 63a determines that it is within the allowable range (−β ≦ X−Y ≦ β), the focus lens 45 falls within the narrow search range (second search range) shown in FIG. And a narrow area search start position M and a narrow area search end position N corresponding to the narrow area search range are output to the CPU 40. The narrow area search range is narrower than the above-described entire area search range and includes the previous focus position G. The narrow area search start position M and the narrow area search end position M are the previous focus positions. It is set before and after the position G.

  Further, as shown in Table 1 below, the entire area search start position P, the entire area search end position Q, the narrow area search start position M, and the narrow area search end position N are changed according to the position of the zoom lens 43, and are narrow. The position and width of the area and the entire search range are changed. For example, when the zoom lens is at the position Z1 (WIDE end), the entire area search start position P = P1, the entire area search end position Q = Q1, the narrow area search start position M = M1, and the narrow area search start position corresponding to this position. N = N1.

  When the previous photometric value X and the focus position are not stored in the RAM 42, the search range setting unit 63 sets the search range of the focus lens 45 as the entire search range, and the entire search start position corresponding to this entire search range. P and the global search end position Q are output to the CPU 40.

  The CPU 40 controls the search range setting unit 63 to set the search range of the focus lens 45, moves the focus lens 45 based on the search range set by the search range setting unit 63, and performs AF search processing. .

  The image signal processing unit 64 performs various types of image processing such as gradation conversion processing, color interpolation processing, and YC conversion processing while the image data is stored in the frame memory 60. When low-resolution image data for a through image is stored in the frame memory 60, the image signal is applied to the LCD driver 66 via the data bus after the image processing is performed by the image signal processing unit 64. Sent. The LCD driver 66 performs signal processing on the image data to display an image on the LCD 16 in order to display an image on the LCD 16.

  When high-resolution image data for recording is stored in the frame memory 60, the image signal processing unit 64 performs the above-described image processing, and then the compression / decompression processing unit 65 applies the image data to the image data. Compression processing is performed in a compression format such as JPEG. The compressed image data is recorded by the media controller 67 on the memory card 31 as a recording medium.

  In the playback mode, image data is read from the memory card 31 by the media controller 67 and temporarily stored in the frame memory 60. The compression / decompression processing unit 65 decompresses the image data. Processing is performed, and this image is displayed on the LCD 16.

  Next, photographing processing of the digital camera 10 having the above configuration will be described with reference to the flowcharts of FIGS. When the digital camera 10 is set to the shooting mode, the CPU 40 determines whether or not the shutter button 28 is half-pressed. When it is determined that the shutter button 28 is not half-pressed, the standby state is maintained until the shutter button 28 is half-pressed.

  If it is determined that the shutter button 28 is half-pressed, it is determined whether the photometric value X and the in-focus position G are stored in the RAM 42. When it is determined that the photometric value X and the focus position G are not stored in the RAM 42, the CPU 40 acquires the photometric value X from the AE detector 61 and performs exposure control based on the photometric value X. Thereafter, the CPU 40 controls the search range setting unit 63 to set the search range. At this time, since the photometric value X and the focus position G are not input to the search range setting unit 63, the search range is set to the global search, and the global search start position P and the global search end position Q are set to the CPU 40. Output. The CPU 40 moves the focus lens 45 based on the whole area search start position P and the whole area search end position Q, and performs AF search processing.

  The AF search process will be described below with reference to the flowchart in FIG. The CPU 40 sets an AF area for calculating the AF evaluation value. This AF area is set at the center of the image picked up by the CCD image sensor 52.

  Further, the CPU 40 sets the optimum exposure (aperture, electronic shutter speed, etc.), CCD drive mode, and sensitivity (gain) for the AF search based on the photometric value acquired from the AE detector 61.

  Further, the CPU 40 sets a filter band in accordance with the CCD drive mode used for the AF search. This filter is a filter for extracting only high-frequency components of image data. The CPU 40 moves the focus lens 45 to the entire area search start position P.

  Thereafter, while the focus lens 45 is moved step by step to the entire area search end position Q, the CPU 40 sequentially calculates the AF evaluation value based on the image data, and detects the maximum value of the AF evaluation value. For example, when the global search start position P is set to the INF end side and the global search end position Q is set to the NEAR end side, the CPU 40 moves from the INF end side to the NEAR end side as shown in FIG. As the focus lens 45 is moved, the AF detector 62 is controlled to detect the maximum AF evaluation value. Note that the above-described one step is one permissible confusion circle diameter, and this step width varies depending on the position of the zoom lens (WIDE end or TELE end). That is, the number of steps increases at the TELE end. Thus, the AF search process ends.

  When it is determined that the photometric value X and the in-focus position G are stored in the RAM 42, the CPU 40 obtains the photometric value Y from the AE detector 61 and performs exposure control based on the photometric value Y. Further, the CPU 40 acquires the previous photometric value X and the focus position G stored in the RAM 42, and inputs the two photometric values X and Y and the focus position G to the search range setting unit 63.

  The search range setting unit 63 determines whether or not the photometric value change amount (X−Y) is within an allowable range (−β ≦ X−Y ≦ β). When it is determined that it is not within the allowable range (−β ≦ X−Y ≦ β), the entire area search range is set as the search range of the focus lens 45, the entire area search start position P corresponding to the entire area search range, and the entire area The search end position Q is output to the CPU 40. Based on the start position P and end position Q, the CPU 40 moves the focus lens 45 in the whole area search range, and performs the AF search process in the same manner as described above.

  When it is determined that the value is within the allowable range (−β ≦ X−Y ≦ β), the search range setting unit 63 sets a narrow range search range as the search range of the focus lens 45, and this narrow range search range. The narrow area search start position M and the narrow area search end position N corresponding to are output to the CPU 40. The narrow area search start position M and the narrow area search end position N are set before and after the previous focus position G, for example, before and after the previous focus position G as shown in FIG. Is done. The narrow area search start position N and the narrow area search end position M may be two steps before and after the in-focus position, or may be three positions before and after the focus position, and can be set as appropriate. Based on the narrow area search start position M and the narrow area search end position N, the CPU 40 moves the focus lens 45 in the narrow area search range, and performs the AF search process as described above.

  Thereafter, the CPU 40 controls the AF peak determination unit 68 to determine whether or not the maximum AF evaluation value detected by the AF search process is an AF peak. When it is determined that the maximum AF evaluation value is not the AF peak, the CPU 40 moves the focus lens 45 to the pan focus position. If it is determined that the maximum AF evaluation value is the AF peak, the position corresponding to the maximum value is determined to be the in-focus position, and the CPU 40 moves the focus lens 45 to the in-focus position. .

  The CPU 40 updates the previous photometric value X and focus position G stored in the RAM 42 to the current photometric value and focus position. When the photometric value X and the focus position G are not stored in the RAM 42, the current photometric value and the focus position are newly stored in the RAM 42.

  Thereafter, the CPU 40 determines whether or not the half-press of the shutter button 28 is released. If it is determined that the half-press has been released, it is determined whether or not an operation button other than the shutter button 28 (for example, the mode switch 21 and the zoom button 24) has been operated. When it is determined that the operation buttons other than the shutter button 28 are not operated, the process returns to the determination process of whether or not the shutter button 28 is half-pressed. If it is determined that an operation button other than the shutter button 28 is operated, the photometric value A and the focus position G stored in the RAM 42 are invalidated (erased), and whether or not the shutter button 28 is half-pressed. Return to the determination process.

  When it is determined that the half-press of the shutter button 28 has not been released, the CPU 40 determines whether or not the shutter button 28 has been fully pressed. If it is determined that the shutter button 28 has not been fully pressed, the process returns to the determination process of whether or not the half-press of the shutter button 28 has been released. If it is determined that the shutter button 28 has been fully pressed, the CPU 40 controls each unit to execute imaging.

  Thereafter, the CPU 40 controls the compression / decompression processing unit 65 to compress the image data, and then controls the media controller 67 to record the compressed image data on the memory card 31. This completes the shooting process.

  As described above, when the change amount of the photometric value is within the allowable range, it is determined that the subject to be imaged is not changed, the search range of the focus lens 45 is set to the narrow range search range, and the narrow range is set. AF search processing is performed. For this reason, the time required for the focus adjustment processing of the photographing lens can be shortened.

  In the first embodiment, the case where the previous photometric value X and the in-focus position G are stored in the RAM 42 has been described. However, even if the power is turned off, the data is not erased even if stored in a flash memory. good. Further, the previous photometric value X and focus position G may be stored in the memory in the search range setting unit 63.

  Moreover, although the case where the photometric value determination unit 63 a is provided in the search range setting unit 63 has been described as an example, it may be provided outside the search range setting unit 63. Furthermore, although the case where the focus lens 45 is moved from the INF end side to the NEAR end side and the AF search process is performed has been described as an example, the present invention is not limited to this, and conversely, the focus lens 45 is moved from the NEAR end side to the INF end side. May be.

  Next, a digital camera 70 according to the second embodiment will be described. The digital camera 70 is provided with a search range setting unit 71 as shown in FIG. Unlike the digital camera 10, the RAM 42 stores the maximum AF evaluation value A and the focus position G in the previous focus adjustment.

  When the AF evaluation value A and the in-focus position G are not stored in the RAM 42, the CPU 40 determines the maximum AF evaluation value detected by the AF detection unit 62 when the shutter button 28 is half-pressed to perform focus adjustment. The value A and the focus position G of the focus lens 45 are stored in the RAM 42. When the shutter button 28 is half-pressed and the focus adjustment is performed in a state where the maximum value A and the focus position G are stored in the RAM 42, the CPU 40 detects the maximum AF evaluation value from the AF detection unit 62. The value B is detected, and the previous maximum value A, the previous in-focus position G, and the current maximum value B stored in the RAM 42 are input to the search range setting unit 71.

  As shown in FIG. 12, the search range setting unit 71 includes, as internal parameters, a change value α of the maximum value of the AF evaluation value, a global search start position P, a global search end position Q, a narrow area search start position M, and a narrow area. The area search end position N is stored, and as described above, the maximum value A of the previous AF evaluation value, the previous focus position G, and the maximum value B of the current AF evaluation value are input. Further, the search range setting unit 71 compares the maximum values A and B, and determines whether or not the amount of change is within an allowable range (−α ≦ A−B ≦ α). A value determination unit 71a is provided.

  When the previous maximum value A and the previous in-focus position G are not stored in the RAM 42, the search range setting unit 71 sets the search range of the focus lens 45 to the entire search range (first search range). The global search start position P and global search end position Q corresponding to the global search range are output to the CPU 40. Further, when the previous maximum value A and the previous focus position G are stored in the RAM 42, the search range setting unit 71 sets the search range of the focus lens 45 as a narrow search range (second search range). The narrow area search start position M and the narrow area search end position N corresponding to this narrow area search range are output to the CPU 40.

  In addition, the AF evaluation value determination unit 71a compares the maximum value A of the previous AF evaluation value stored in the RAM 42 with the maximum value B of the AF evaluation value detected by performing the AF search process in the narrow area search range. Then, it is determined whether or not the change amount (A−B) of the AF evaluation value is within an allowable range (−α ≦ A−B ≦ α). When it is determined that the allowable range (−α ≦ A−B ≦ α) is not satisfied, the search range setting unit 71 sets the search range of the focus lens 45 as a global search range, and the global search corresponding to the global search range. The start position P and the global search end position Q are output to the CPU 40.

  Note that the entire area search range and the narrow area search range are the same as those of the digital camera 10, and this narrow area search range is narrower than the entire area search range and includes the previous in-focus position G. The narrow area search start position M and the narrow area search end position M are set before and after the previous focusing position G. Further, the entire area search start position P, the entire area search end position Q, the narrow area search start position M, and the narrow area search end position N are zoomed as shown in Table 1, as in the case of the digital cameras 10 and 70 described above. The position is changed according to the position of the lens 43, and the position and width of the narrow area and the entire area search range are changed.

  The rest of the configuration is the same as that of the digital camera 10, and the same reference numerals are given and detailed description thereof is omitted.

  Next, photographing processing of the digital camera 70 having the above configuration will be described with reference to the flowcharts of FIGS. When the shooting mode is set, the CPU 40 determines whether or not the shutter button 28 is half-pressed. When it is determined that the shutter button 28 is not half-pressed, the standby state is maintained until the shutter button 28 is half-pressed.

  If it is determined that the shutter button 28 is half-pressed, the CPU 40 determines whether the maximum value A and the focus position G of the previous AF evaluation value are stored in the RAM 42. When it is determined that the maximum value A and the focus position G are not stored in the RAM 42, the CPU 40 controls the search range setting unit 71 to set the search range. At this time, since the maximum value A and the in-focus position G are not input to the search range setting unit 71, the entire area search range is set as the search range of the focus lens 45, and the entire area search corresponding to the entire area search range is started. The position P and the global search end position Q are output to the CPU 40.

  Based on the global search range start position P and global search end position Q, the CPU 40 performs an AF search process in the global search range, as shown in FIG. 15, and obtains the maximum AF evaluation value A. Thereafter, the process proceeds to a process of determining whether or not the maximum AF evaluation value A is an AF peak.

  When it is determined that the maximum value A and the in-focus position G are stored in the RAM 42, the CPU 40 inputs the maximum value A and the in-focus position G into the search range setting unit 71. When the maximum value A and the focus position G are input, the search range setting unit 71 sets a narrow search range as the search range of the focus lens 45, and the narrow search start position M corresponding to the narrow search range. The narrow area search end position N is output to the CPU 40. Based on the narrow area search start position M and the narrow area search end position N, the CPU 40 performs an AF search process in the narrow area search range as shown in FIG. 16, and obtains the maximum AF evaluation value B.

  The CPU 40 inputs this maximum value B to the search range setting unit 71. The AF evaluation value determination unit 71a compares the maximum value A and the maximum value B of the AF evaluation value, and whether the change amount (A−B) is within an allowable range (−α ≦ A−B ≦ α). Determine whether or not. When it is determined that the value is within the allowable range (−α ≦ A−B ≦ α), the CPU 40 determines that the position corresponding to the maximum value B is the in-focus position, and moves the focus lens 45 to this position. . For example, as shown in FIG. 16, when the maximum value B is not different from the previous maximum value A, it is determined that this position is the in-focus position, and the AF search process in the entire area search range is not performed.

  If it is determined that the value is not within the allowable range (−α ≦ A−B ≦ α), the search range setting unit 71 sets a global search range as the search range of the focus lens 45 and corresponds to the global search range. The entire area search start position P and the entire area search end position Q are output to the CPU 40. Based on the global search start position P and the global search end position Q, the CPU 40 performs an AF search process in the global search range to obtain the maximum AF evaluation value B. For example, as shown in FIG. 17, when the maximum value B falls below the allowable value α below the maximum value A, the AF search process is performed in the entire area search range, and the maximum value B of the AF evaluation value is acquired again. Thereafter, the process proceeds to a process of determining whether or not the maximum AF evaluation value B is an AF peak.

  Processing for determining whether or not the maximum AF evaluation value is an AF peak is performed by the AF peak determination unit 68. The AF peak determination unit 68 determines whether or not the maximum AF evaluation value is an AF peak. When it is determined that the maximum value of the AF evaluation value is the AF peak, the CPU 40 determines that the position corresponding to the maximum value is the in-focus position, and moves the focus lens 45 to the in-focus position. When it is determined that the maximum AF evaluation value is not the AF peak, the CPU 40 moves the focus lens 45 to the pan focus position.

  After the focus lens 45 is moved to the focus position or the pan focus position, the CPU 40 updates the previous maximum value A and focus position G stored in the RAM 42 to the current maximum value and focus position. If the maximum value A and the in-focus position G are not stored in the RAM 42, the current maximum value and in-focus position are newly stored in the RAM 42.

  Thereafter, the CPU 40 determines whether or not the half-press of the shutter button 28 is released. If it is determined that the half-press is released, it is determined whether an operation button other than the shutter button 28 (for example, the mode switch 21 or the zoom button 24) is operated. When it is determined that the operation buttons other than the shutter button 28 are not operated, the process returns to the determination process of whether or not the shutter button 28 is half-pressed. If it is determined that an operation button other than the shutter button 28 has been operated, the maximum value A and the focus position G stored in the RAM 42 are invalidated, and a determination process is performed to determine whether the shutter button 28 has been pressed halfway. Return.

  When it is determined that the half-press of the shutter button 28 has not been released, the CPU 40 determines whether or not the shutter button 28 has been fully pressed. If it is determined that the shutter button 28 has not been fully pressed, the process returns to the determination process of whether or not the half-press of the shutter button 28 has been released. If it is determined that the shutter button 28 has been fully pressed, the CPU 40 controls each unit to execute imaging.

  Thereafter, the CPU 40 controls the compression / decompression processing unit 65 to compress the image data, and then controls the media controller 67 to record the compressed image data on the memory card 31. This completes the shooting process.

  As described above, when the shutter button 28 is operated, AF search processing is performed in the narrow search range, and the maximum AF evaluation value B detected by this AF search processing and the maximum AF evaluation value of the previous time are detected. A is compared, and when the amount of change is within the allowable range, the position corresponding to the maximum value B is set as the in-focus position. For this reason, it is possible to shorten the time required for the focus adjustment processing of the photographic lens 13.

  Although the case where the maximum value A and the focus position G of the previous AF evaluation value are stored in the RAM 42 has been described, they may be stored in a flash memory that does not erase data even when the power is turned off. Further, the previous maximum value A and in-focus position G may be stored in a memory in the search range setting unit 71.

  Moreover, although the case where the AF evaluation value determination unit 71 a is provided in the search range setting unit 71 has been described as an example, it may be provided outside the search range setting unit 71. Furthermore, although the case where the focus lens 45 is moved from the INF end side to the NEAR end side and the AF search process is performed has been described as an example, the present invention is not limited to this, and conversely, the focus lens 45 is moved from the NEAR end side to the INF end side. May be.

  Next, a digital camera 80 according to the third embodiment will be described. As shown in FIG. 18, the digital camera 80 is provided with a search range setting unit 80. Unlike the digital cameras 10 and 70, the digital camera 80 does not store the photometric value, the maximum AF evaluation value, or the previous in-focus position in the RAM 42. The search range setting unit 80 receives the maximum AF evaluation value D as will be described later.

  As shown in FIG. 19, the search range setting unit 81 includes, as internal parameters, an AF evaluation value reference value E, a global search start position P, a global search end position Q, a narrow search start position M, and a narrow search. The starting position N is stored. When the shutter button 28 is half-pressed, the search range setting unit 81 first sets a narrow range search range (first search range) as the search range of the focus lens 45, and the narrow range search range is set to this narrow range search range. The corresponding narrow area search start position M and narrow area search end position N are output to the CPU 40.

  Further, the search range setting unit 81 receives the maximum AF evaluation value D acquired by the AF search process in the narrow range search range described above. The search range setting unit 81 includes an AF evaluation value determination unit 81a that compares the maximum value D with a reference value E and determines whether the maximum value D is equal to or greater than the reference value E.

  When the AF evaluation value determination unit 81a determines that the maximum value D is greater than or equal to the reference value E, the search range setting unit 80 does not output the search range. At this time, the CPU 40 determines that the maximum value D of the AF evaluation value is the AF peak, and moves the focus lens 45 with this position as the in-focus position. If it is determined that the maximum value D is smaller than the reference value E, a global search range (second search range) is set as the search range of the focus lens 45, and the global search start position P corresponding to this global search range. , And the global search end position Q is output.

  As shown in FIG. 20, this whole area search range is a search range in which a temperature special margin which is an oversearch amount for absorbing an error caused by the temperature characteristic of the photographing lens 13 is added to the narrow area search range. It is. Further, the entire area search start position P, the entire area search end position Q, the narrow area search start position M, and the narrow area search end position N are zoomed as shown in Table 1, as in the case of the digital cameras 10 and 70 described above. The position is changed according to the position of the lens 43, and the position and width of the narrow area and the entire area search range are changed.

  Other configurations are the same as those of the digital cameras 10 and 70, and the same components are denoted by the same reference numerals and detailed description thereof is omitted.

  Next, photographing processing of the digital camera 80 having the above configuration will be described with reference to the flowcharts of FIGS. When the shooting mode is set, the CPU 40 determines whether or not the shutter button 28 is half-pressed. When it is determined that the shutter button 28 is not half-pressed, the standby state is maintained until the shutter button 28 is half-pressed.

  When it is determined that the shutter button 28 is half-pressed, the CPU 40 controls the search range setting unit 81 to set the search range. At this time, the search range setting unit 81 sets a narrow area search range as the search range of the focus lens 45, and the CPU 40 determines the narrow area search start position M and the narrow area search end position N corresponding to the narrow area search range. Output to.

  As shown in FIG. 20, after moving the focus lens 45 to the narrow area search start position M, the CPU 40 moves the focus lens 45 to the narrow area search end position N, and performs AF search processing in the narrow area search range. Do. Further, the CPU 40 acquires the maximum value D of the AF evaluation value from the AF detection unit 62 and inputs this maximum value D to the search range setting unit 81.

  The AF evaluation value determination unit 81a compares the maximum value D with the AF evaluation reference value E and determines whether D ≧ E. When it is determined that D ≧ E, the search range is not output from the search range setting unit 81. At this time, the CPU 40 determines that the position where the maximum value D is the AF peak and this position is the in-focus position, and moves the focus lens 45 to a position corresponding to the maximum value D.

  If it is determined that D ≧ E, the search range setting unit 81 sets a global search range as the search range of the focus lens 45, the global search start position P corresponding to this global search range, and the global search. The end position Q is output to the CPU 40. As shown in FIG. 20, the CPU 40 moves the focus lens 45 in the entire area search range, performs AF search processing, and obtains the maximum AF evaluation value D again. Thereafter, the process proceeds to a process of determining whether or not the maximum AF evaluation value D is an AF peak.

  Processing for determining whether or not the maximum value D is an AF peak is performed by the AF peak determination unit 68. The AF peak determination unit 68 determines whether or not the maximum value D is an AF peak. When it is determined that the maximum value D is the AF peak, the CPU 40 determines that the position corresponding to the maximum value D is the in-focus position, and moves the focus lens 45 to the in-focus position. When it is determined that the maximum value D is not the AF peak, the CPU 40 moves the focus lens 45 to the pan focus position.

  Thereafter, the CPU 40 determines whether or not the half-press of the shutter button 28 is released. When it is determined that the half-press of the shutter button 28 is released, the process returns to the process of determining whether the shutter button 28 is half-pressed. When it is determined that the half-press of the shutter button 28 has not been released, the CPU 40 determines whether or not the shutter button 28 has been fully pressed.

  If it is determined that the shutter button 28 has not been fully pressed, the process returns to the determination process of whether or not the half-press of the shutter button 28 has been released. If it is determined that the shutter button 28 has been fully pressed, the CPU 40 controls each unit to execute imaging.

  Thereafter, the CPU 40 controls the compression / decompression processing unit 65 to compress the image data, and then controls the media controller 67 to record the compressed image data on the memory card 31. This completes the shooting process.

  As described above, when the shutter button 28 is half-pressed, first, an AF search process is performed in a narrow search range that does not include the temperature special margin, and the maximum AF evaluation value D acquired by this AF search process is obtained. When the reference value E is equal to or greater than the reference value E, the position corresponding to the maximum value D is set as the focus position. For this reason, it is possible to shorten the time required for the focus adjustment processing of the photographic lens 13.

  In the third embodiment, the case where the AF evaluation value determination unit 81a is provided in the search range setting unit 81 has been described as an example. However, the AF evaluation value determination unit 81a may be provided outside the search range setting unit 81. Further, the focus lens 45 is moved from the INF end side to the NEAR end side during the narrow area search, and is moved from the NEAR end side to the INF end side during the entire area search. It may be moved from the end side to the INF end side, and may be moved from the INF end side to the NEAR end side during the entire area search.

  In the above-described embodiment, the case where a CCD image sensor is used as a solid-state imaging device has been described as an example. However, the present invention is not limited to this, and for example, a CMOS image sensor may be used.

  In the above embodiment, the case where the photographing apparatus of the present invention is applied to a digital camera has been described as an example. However, the present invention is not limited to this, and the present invention is not limited to a mobile phone with a camera or a digital video camera capable of photographing a still image. The invention may be applied.

It is an external appearance perspective view which shows the structure of the front side of a digital camera. It is an external appearance perspective view which shows the structure of the back side of a digital camera. It is a block diagram which shows the electric constitution of the digital camera of 1st Embodiment. It is explanatory drawing which shows the search range setting part of the digital camera which is 1st Embodiment. It is explanatory drawing which shows the whole region search range and narrow region search range of the digital camera which is 1st Embodiment. 3 is a flowchart for describing photographing processing of the digital camera of the first embodiment. 3 is a flowchart for describing photographing processing of the digital camera of the first embodiment. It is a flowchart explaining AF search processing. It is a graph which shows the change of AF evaluation value at the time of AF search process. It is explanatory drawing which shows the whole region search range and narrow region search range of the digital camera which is 1st Embodiment. It is a block diagram which shows the electric constitution of the digital camera of 2nd Embodiment. It is explanatory drawing which shows the search range setting part in the digital camera which is 2nd Embodiment. It is a flowchart explaining the imaging | photography process of the digital camera which is 2nd Embodiment. It is a flowchart explaining the imaging | photography process of the digital camera which is 2nd Embodiment. It is explanatory drawing which shows the whole area search range in the digital camera which is 2nd Embodiment. It is explanatory drawing which shows the narrow area search range in the digital camera which is 2nd Embodiment, and has shown the case where the maximum value of AF evaluation value is in a tolerance | permissible_range by the AF search process in a narrow area search range. It is explanatory drawing which shows the whole area search range and narrow area search range in the digital camera which is 2nd Embodiment, and shows the case where the maximum value of AF evaluation value is outside an allowable range by AF search processing in the narrow area search range. Yes. It is a block diagram which shows the electric constitution of the digital camera of 3rd Embodiment. It is explanatory drawing which shows the search range setting part in the digital camera of 3rd Embodiment. It is explanatory drawing which shows the whole area search range and the narrow area search range in the digital camera of 3rd Embodiment. 10 is a flowchart for describing photographing processing of a digital camera according to a third embodiment. 10 is a flowchart for describing photographing processing of a digital camera according to a third embodiment.

Explanation of symbols

10, 70, 80 Digital camera 11 Camera body 13 Shooting lens 40 CPU
42 RAM
43 Zoom lens 45 Focus lens 52 CCD image sensor 63, 71, 81 Search range setting unit 63a Photometric value determination unit 71a AF evaluation value determination unit 81a AF evaluation value determination unit A, B, D Maximum value of AF evaluation value E AF evaluation Value reference value G In-focus position M Narrow-area search start position N Narrow-area search end position P All-area search start position Q All-area search end position X, Y Photometric value

Claims (10)

When the shutter button is operated, an AF evaluation value that is an integral value of high-frequency components of image data captured by the solid-state image sensor is sequentially calculated while moving the focus lens within a predetermined search range, and these AF evaluation values In the photographing apparatus for adjusting the focus of the photographing lens by moving the focus lens to the in-focus position based on
A photometric means for performing photometry based on the image data when the shutter button is operated;
Storage means for storing the photometric value measured by the photometric means and the in-focus position;
A photometric value determination unit that compares the photometric value measured by the photometric unit with the previous photometric value stored in the photometric value storage unit, and determines whether or not the amount of change is within an allowable range;
When the photometric value determination means determines that the value is outside the allowable range, the search range is set to the first search range, and when it is determined that the value is within the allowable range, Narrow search range setting means for setting a second search range including the previous in-focus position stored in the storage means;
When the shutter button is operated, the search range setting means is controlled to set the search range, the focus lens is moved within the search range set by the search range setting means, and focus adjustment is performed. An imaging apparatus comprising: a control unit that updates the photometric value and the in-focus position stored in the storage unit.   The search range setting means sets the search range to the first search range when the photometric value and the in-focus position are not stored in the storage means, and the control means sets the first search range. 2. The photographing apparatus according to claim 1, wherein the focus lens is moved within a range to perform focus adjustment, and the photometric value and the in-focus position are stored in the storage unit.   3. The control unit according to claim 1, wherein the control unit invalidates the photometric value and the in-focus position stored in the storage unit when an operation button other than the shutter button is operated. Shooting device.   4. The photographing lens according to claim 1, wherein the photographing lens includes a zoom lens, and the width and position of the first and second search ranges are changed based on the position of the zoom lens. The imaging device described. When the shutter button is operated, an AF evaluation value that is an integral value of high-frequency components of image data captured by the solid-state image sensor is sequentially calculated while moving the focus lens within a predetermined search range, and these AF evaluation values In the photographing apparatus for adjusting the focus of the photographing lens by moving the focus lens to the in-focus position based on
An AF detection means for calculating the AF evaluation value and detecting a maximum value of the AF evaluation value;
Storage means for storing the maximum value of the AF evaluation value detected by the AF detection means and the in-focus position;
AF evaluation for comparing the maximum value detected by the AF detection means with the maximum value at the time of the previous focus adjustment stored in the storage means and determining whether or not the change amount is within an allowable range. Value judging means;
When the maximum value and the in-focus position are not stored in the storage unit, the search range is set as a first search range, and the maximum value and the in-focus position are stored in the storage unit The second search range is narrower than the first search range and includes the previous in-focus position stored in the storage unit, and the AF evaluation value determination unit sets the second search range in the second search range. Search range setting means for setting the search range to the first search range when it is determined that the amount of change is outside the allowable range;
When the shutter button is operated, the search range setting means is controlled to set the search range, the focus lens is moved within the search range set by the search range setting means, and focus adjustment is performed. An imaging apparatus comprising: a control unit that updates the maximum value stored in the storage unit and the in-focus position.   6. The photographing apparatus according to claim 5, wherein the control unit invalidates the maximum value and the in-focus position stored in the storage unit when an operation button other than the shutter button is operated. .   7. The photographing lens according to claim 5, wherein the photographing lens includes a zoom lens, and the width and position of the first and second search ranges are changed based on the position of the zoom lens. The photographing apparatus described. When the shutter button is operated, an AF evaluation value that is an integral value of high-frequency components of image data captured by the solid-state image sensor is sequentially calculated while moving the focus lens within a predetermined search range, and these AF evaluation values In the photographing apparatus for adjusting the focus of the photographing lens by moving the focus lens to the in-focus position based on
An AF detection means for calculating the AF evaluation value and detecting a maximum value of the AF evaluation value;
The maximum value detected by the AF detection unit by moving the focus lens in the first search range is compared with a reference value for evaluating the maximum value, and the maximum value is equal to or greater than the reference value. AF evaluation value determining means for determining whether or not there is,
When the shutter button is operated, a first search range is set as the search range, and when the AF evaluation value determining unit determines that the maximum value is not equal to or greater than the reference value, the first search range is set. Search range setting means for setting a second search range wider than the search range;
An imaging apparatus comprising: control means for controlling the search range setting means to set the search range and moving the focus lens within the search range set by the search range setting means.   9. The search range according to claim 8, wherein the second search range is a search range obtained by adding an oversearch amount for absorbing an error due to a temperature characteristic of the photographing lens to the first search range. Shooting device. 10. The photographing lens according to claim 8, wherein the photographing lens includes a zoom lens, and the width and position of the first and second search ranges are changed based on the position of the zoom lens. The imaging device described.

Images