JP4283268B2 - Imaging device - Google Patents

Description

  The present invention relates to an imaging apparatus, and more particularly to an improvement of an imaging apparatus provided with two focusing means that perform different types of focusing operations.

  Conventionally, still cameras and video cameras (hereinafter referred to as still cameras and the like) are equipped with an autofocus device that automatically and optimally adjusts the focus of a subject image.

  Then, an autofocus device in a conventional still camera or the like that records a subject image as an image or video on a recording medium such as a film or a video tape irradiates the subject with infrared rays or ultrasonic waves, for example, to generate a reflected wave from the subject. On the other hand, so-called external light AF (autofocus) is used in which the so-called triangulation principle is applied to calculate the distance to the subject, and the focus lens is moved to the in-focus position corresponding to the calculated distance. It was.

  On the other hand, in an electronic camera (hereinafter also referred to as a digital camera as appropriate) that projects a subject image onto an imaging means such as a CCD and extracts the projected image as an electrical signal, it is used as an image signal substantially simultaneously with the projection of the image. Since it can be taken out, the AF operation can be performed on the basis of the subject image actually formed on the image pickup means via a photographing optical system such as a focus lens.

  That is, this AF sequentially evaluates the contrast (including the sharpness of the image) of the image signal obtained by the imaging means in real time each time the focus lens is moved, and the value of this evaluation is a maximum. The movement of the photographic optical system is stopped at a position, which is called CCDAF or hill-climbing contrast AF.

  Since this CCDAF is an AF performed by evaluating an image actually projected on the image pickup means, the focusing accuracy is very high.

  Since the CCDAF is performed while comparing the evaluation value for each moving position while moving the focus lens, the focusing accuracy can be improved as the repetition frequency for detecting the image signal representing the subject image is increased.

  On the other hand, if the repetition frequency of a series of operations such as image accumulation, transfer, evaluation value calculation, and comparison is increased, there is a problem that it takes a long time to determine a focus position (completion of AF operation).

  For this reason, the time required from the start to the completion of the AF operation, that is, the time lag has a significant effect on the focusing of the subject image, for example, when shooting a subject moving at a high speed, etc. You may not be able to shoot at the timing.

  In addition, since CCDAF evaluates an actual subject image, an appropriate focusing operation may not be performed in a dark situation where the overall contrast is low.

  On the other hand, the external light AF described above is inferior in focusing accuracy as compared with the CCD AF, but has a small time lag required for the AF operation, so that it can follow a dynamic subject well and can take an image. It is possible to prevent the timing from being lost.

  Further, the external light AF projects infrared rays and measures the distance based on the image of the reflected wave, and thus has a feature that it is generally not easily influenced by the contrast of the subject.

  In view of this, there has been proposed an AF apparatus that includes AF means for performing these two types of AF operations and is switchable so that any one of the AF means can be selectively selected according to the shooting situation or subject situation. (Patent Document 1 etc.).

  However, according to these techniques, when the user selects either one of the AF operations, the selection operation must be performed in advance regardless of which one is selected.

  In other words, when shooting a dynamic subject, first set the shooting mode to the time lag priority mode (focusing speed priority mode) corresponding to the external light AF by operating the shooting mode switch dial or switch button in advance. On the other hand, when shooting to obtain an image that requires focus accuracy, the switch button or the like is set to a focusing accuracy priority mode corresponding to CCDAF before shooting, and then shooting is started. There was a need.

  Therefore, for example, when a dynamic subject suddenly jumps into the field of view during shooting in the focus accuracy priority mode, and the user wants to take a picture of the dynamic subject, the user must first select the shooting mode. Therefore, it is necessary to switch the AF operation to the time lag priority mode.

  In addition, there is a problem that a desired image cannot be obtained because it takes time for such a switching operation to miss the photographing timing, or the subject is lost because the line of sight is removed from the subject for the switching operation.

  Therefore, the applicant of the present application has proposed an electronic camera in which the AF operation can be appropriately switched within the range of the normal shooting operation / shooting operation (Patent Document 2).

  This electronic camera is configured to switch between the external light AF operation and the CCDAF depending on the operation time required from the half-press position to the full-press position of the release button.

  In other words, when the user presses the entire stroke of the shutter release button all at once, the time required from the half-pressed position to the fully-pressed position is extremely short, reflecting the user's intention to quickly release the shutter. Since this is an operation, the time lag priority external light AF operation is selected.

  On the other hand, if the user temporarily stops the pressing operation at the half-pressed position in the entire stroke of the shutter release button and then presses it down to the fully-pressed position, the time required from the half-pressed position to the fully pressed position Since this is an operation that reflects the user's intention to increase the length and focus carefully, the CCDAF operation giving priority to focusing accuracy is selected.

According to this proposed technique, the user can instantaneously switch between two types of AF operations within the normal photographing operation range of pressing the shutter release button, and the photographing timing It is possible to easily prevent an image from being missed or an erroneously shot image with a poor focus accuracy.
JP 2001-255456 A Japanese Patent Application No. 2002-175297 (not disclosed at the time of application)

  By the way, in the above-described proposed technique, the AF operation is simply switched depending on the length of the elapsed time from the half-press to the full-press of the shutter release button. How is the reference time (threshold value) for this elapsed time set? However, it is important in actual shooting situations.

  For example, it is conceivable to set the reference time as the time required from when the shutter release button is pressed halfway until the external light AF operation is started until the external light AF operation is completed.

  That is, if the shutter release button is fully pressed during the external light AF operation, it is considered that there is an intention to request a quick shooting execution, so that the shooting execution is performed as soon as the external light AF operation is completed. If the shutter release button is fully pressed after the external light AF operation is completed, it is considered that the shooting is not urgently executed, so the camera is switched to CCDAF and the shooting is executed.

  However, the initial position of the focus lens when the shutter release button is pressed halfway to start the external light AF operation is not constant, the position at the previous shooting execution time is the initial position, and is calculated by the external light AF operation. Since the in-focus position also changes in accordance with the distance value to the subject, the time from the start of the external light AF operation (initial position) to the completion of the operation (in-focus position) changes for each shooting.

  For this reason, when the time from the start to the completion of the external light AF operation is set as the reference time, the reference time changes for each photographing and may be set to be significantly shorter than the user's prediction. Conceivable.

  In such a case, even if the shutter release button is half-pressed, fully pressed, or pressed all at once (at once) with the intention of the user selecting the external light AF, There is also a risk of shifting to the CCDAF operation.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an imaging apparatus capable of appropriately switching between two types of AF operations in accordance with shooting conditions within the range of normal shooting operations and operations. To do.

  In order to solve the above-described problem, the imaging apparatus according to the present invention starts the first focusing operation by half-pressing the shutter release button, and the elapsed time from the start of the first focusing operation and the subsequent shutter release button. The first focusing operation and the second focusing operation are controlled in accordance with the pressing state of the first focusing operation. When the first focusing operation is not completed at the time when the reference time has elapsed, the first focusing operation is performed. The focus state by the focus operation is switched to the second focus operation from the starting point.

  That is, an imaging apparatus according to claim 1 of the present invention includes an imaging unit that converts a projected image into an image signal and outputs the image, an imaging optical system that projects an image of the subject on the imaging unit, First distance is obtained by measuring a distance to obtain a distance value and relatively moving at least one of the imaging optical system and at least one of the imaging means to a first focusing position corresponding to the distance value. Evaluating sequential image signals obtained through the photographing optical system while relatively moving at least one of the first focusing means for performing the operation, at least a part of the photographing optical system and the imaging means A second focusing means for performing a second focusing operation for stopping at least one of the imaging optical system and at least one of the imaging means at a second focusing position based on the evaluation; A focusing operation and the second focusing operation; Control means for controlling switching, start signal input means for inputting an instruction for starting a focusing operation, execution signal input means for inputting an instruction for executing an imaging operation, and input of an instruction for starting the focusing operation In the imaging apparatus including the time measuring unit that measures the elapsed time from the time when the start instruction is input to the start signal input unit, the first focusing of the two focusing operations is performed. When the first focusing operation is completed before the elapsed time reaches a preset reference time, the start signal input means is started when the first focusing operation is completed. When the input of the start instruction is maintained and the execution instruction is not input to the execution signal input means, the first instruction is input until the execution instruction is input to the execution signal input means. Together When the elapsed time reaches a preset reference time before the completion of the first focusing operation, the second focusing is performed from the first focusing position. Control is performed to start a focusing operation.

  Here, the imaging device includes an electronic still camera, a video camera similar to the electronic still camera, and various image input devices that capture an image of a subject by operating a shutter.

  The imaging means means a solid-state imaging device such as a CCD or CMOS, another photoelectric conversion device, or the like, and means that can take out a projected image as an electrical signal or the like in substantially real time.

  An imaging optical system means an optical system such as a lens that projects an image of a subject on an image pickup means and forms an image. In an image pickup apparatus in which the image pickup means is fixedly arranged, a focus lens or the like is movable. In an imaging apparatus that includes a lens and is capable of moving the imaging unit relative to the imaging optical system in the optical axis direction of the imaging optical system, the imaging unit can be moved and focused. Therefore, it is not always necessary to include a movable lens.

  To measure the distance to the subject, specifically, for example, a method of projecting infrared rays or ultrasonic waves onto the subject and measuring the distance based on the reflected wave from the subject, and various other known methods are applied. be able to.

  A so-called active AF type or passive AF type may be used.

  Further, measuring the distance to obtain the distance value is not limited to obtaining the “distance value” itself as a physical quantity. For example, an angle related to this “distance value”, such as an angle related to triangulation, or infrared rays The physical quantity such as the reflection arrival time may be obtained, or the distance value as the physical quantity may not be calculated.

  Therefore, when the distance value as the physical quantity is not calculated, the “focus position according to the distance value” means “the focus position according to the physical quantity corresponding to the distance value”.

  For example, so-called external light AF can be applied as the first focusing operation.

A part or all of the photographing optical system and at least one of the imaging means are:
(I) Only a part of the photographic optical system,
(Ii) Only the entire photographic optical system,
(Iii) only imaging means,
(Iv) a part of the photographing optical system and imaging means,
(V) the entire photographing optical system and imaging means;
This means any one of the five aspects.

  Therefore, the relative movement of at least one defined by these aspects is not necessarily limited to moving on the side of the photographing optical system (including only a part of the photographing optical system; the same applies hereinafter). The imaging optical system side may be moved or the imaging unit side may be moved so that the subject image is formed on the imaging unit. It is also possible to move both.

  Evaluating the image signal obtained via the photographing optical system means evaluating the image of the subject projected on the image pickup means, and evaluating the subject image means an image representing the obtained subject image. Based on the signal, for example, a value (differential value of the image signal) corresponding to the focused state of the subject image, such as the contrast and sharpness of the subject image, is obtained, and the maximum value or the maximum value of this value is obtained. Say.

  That is, for example, the sharpness of a subject can be expressed by a differential value of an image signal with respect to a contour portion or the like, and when the differential value is maximized, the subject image is appropriately formed on the imaging means. In other words, it can be said that the subject is in focus.

  Evaluating successive image signals means evaluating the image signals obtained for each relative movement position of at least one of the imaging means and the imaging optical system.

  Note that each movement position may be every appropriate movement distance in the optical axis direction, or in the configuration in which the optical system is moved in the optical axis direction while being rotated spirally around the optical axis, the rotation is appropriate. It may be every angle or every appropriate time interval.

  As the second focusing operation, for example, an AF operation called so-called CCDAF or hill-climbing contrast AF can be applied.

  The time measuring means is not limited to the one that directly measures time, but may be one that includes a pulse generator that generates a clock signal having an appropriate period and a counter that counts the number of pulses of the generated clock signal.

  According to the imaging apparatus of the first aspect of the present invention configured as described above, when the start signal is input to the start signal input unit, the control unit starts the first focusing operation with so-called time lag priority. Preparation for shooting that can deal with a dynamic subject is started (for example, when the shutter release button is pressed, the shutter release button always passes the half-pressed position before reaching the full-pressed position (shooting execution)). Therefore, when passing through the half-pressed position, the control means starts a first focusing operation with so-called time lag priority, and preparations for shooting capable of dealing with a dynamic subject are started.

  Thereafter, depending on the state such as whether the start signal is input to the start signal input means, whether the execution signal is input to the execution signal input means, and the elapsed time by the time measuring means, the control means, In order to control the first focusing operation and the second focusing operation, compared with the case where the first focusing operation and the second focusing operation are simply controlled only by the elapsed time, the intention of switching the actual focusing operation is More precise switching control can be performed (for example, the state of pressing the shutter release button, that is, whether the shutter release button is maintained at the half-pressed position or fully pressed down, and the elapsed time by the time measuring means) Therefore, since the control means controls the first focusing operation and the second focusing operation, compared with the case where the first focusing operation and the second focusing operation are controlled only by the elapsed time. Of the switching 換意 view of the focusing operation can be performed more finely the corresponding switching control).

  In addition, the second focusing operation is not inadvertently moved, and the first focusing operation can be performed at any time in a state where the first focusing operation is completed, that is, a dynamic subject is tracked and in focus. it can.

  Further, if the first focusing operation is not completed even after a predetermined reference time has elapsed from the start of the first focusing operation, the position of the imaging optical system or the imaging means at the start of the first focusing operation is in-focus. It is considered that there is an intention not to rush to release the shutter because the photographing execution operation has not been performed at the time when the reference time has elapsed, and thus the focusing accuracy is high. By performing control to switch to the second focusing operation, it is possible to execute a shooting operation in accordance with the user's intention.

  In addition, since the focus position of the imaging optical system or the imaging means by the first focusing operation becomes the start position of the second focusing operation, the evaluation is performed over the entire stroke of the imaging optical system or the imaging means (of the focusing position). (Search scanning) does not need to be performed, and the time from the start of the second focusing operation to the focusing can be increased compared to the case where the entire stroke is evaluated.

  In addition, the imaging apparatus according to claim 2 of the present invention, after the completion of the first focusing operation, when the shooting execution instruction is input within the reference time, the completion of the first focusing operation as it is. Shooting is performed in a focused state.

  That is, an imaging apparatus according to a second aspect of the present invention is the imaging apparatus according to the second aspect of the present invention, wherein the control means is configured such that when the start instruction is input to the start signal input means, The first focusing operation is started in the focusing operation, and the first focusing operation is completed before the elapsed time reaches a preset reference time. The execution instruction is input to the execution signal input means when the input of the start instruction to the start signal input means is maintained at the time of completion and the execution instruction is not input to the execution signal input means. Until the elapsed time reaches the reference time from the time when the first focusing operation is completed. Instruction entered It has been if, and controls so as to execute the imaging operation while maintaining the completion status of the first Go focusing operation.

  According to the imaging apparatus according to claim 2 of the present invention configured as described above, a state in which the image is focused at a high speed by the first focusing operation in accordance with a user's intention to release a shutter at a high speed. Shooting can be performed with.

  In the image pickup apparatus according to claim 3 of the present invention, the first focusing means sets the first focus target position corresponding to the distance value as the normal focus position.

  That is, in the imaging apparatus according to claim 3 of the present invention, in the imaging apparatus according to claim 1 or 2 of the present invention, the first focusing means cannot obtain the distance value with preset accuracy. In addition, the normal focus position is set as the first focus position, and the control means is a position when the first focus operation is completed after the first focus operation is completed, regardless of the elapsed time. The second focusing operation is controlled so as to start.

  Here, for example, when the direction of the contour line of the subject is unsuitable for measuring the distance value in the first focusing operation, or the subject has a low contrast and the passive AF element is not good, the distance value is set. It may not be possible to calculate or the measured distance value may be unreliable.

  In such a case, the first focusing means cannot set the focusing target position itself according to the distance value.

  However, according to the imaging device according to claim 3 of the present invention configured as described above, the first focusing means sets the so-called normal focus position as the focus target position, and therefore performs the first focusing operation. It can be carried out.

  In addition, since the position (ordinary focus position) of the imaging optical system or the imaging means at the time when the first focusing operation is completed becomes the start position of the second focusing operation, evaluation is performed over the entire stroke of the imaging optical system or imaging means. There is no need to perform (focus position search scanning), and the time from the start of the second focusing operation to focusing can be increased compared to the case of evaluating over the entire stroke.

  According to a fourth aspect of the present invention, the start signal input means and the execution signal input means are shutter release buttons.

  That is, an imaging device according to a fourth aspect of the present invention is the imaging device according to any one of the first to third aspects of the present invention, further comprising a shutter release button, and the start signal input means and the execution signal. Each of the input means is a shutter release button, and the start instruction is input at a half-pressed position of the shutter release button, and the execution instruction is input at a full-pressed position of the shutter release button. .

  Here, the half-pressed position of the shutter release button does not need to be the middle position of the entire stroke of the shutter release button, and the position when the shutter release button is not pressed at all and when the full stroke is pressed. It may be any position between the position and the fully pressed position that is the position before that, so that the user can recognize that the shutter release button has been pressed down to the half pressed position. It is preferable to provide a member or the like that gives a feeling or resistance.

  According to the imaging apparatus of the fourth aspect of the present invention configured as described above, when the shutter release button is pressed, the shutter release button always passes the half-pressed position before reaching the full-pressed position (shooting execution). Therefore, at the point of passing through this half-pressed position, the control means starts the first focusing operation with a so-called time lag priority, and the preparation for shooting capable of dealing with a dynamic subject is started.

  Thereafter, the control means determines whether or not the shutter release button is pressed, that is, whether the shutter release button is maintained at the half-pressed position or fully pressed down, and the elapsed time by the time measuring means. Compared with the case where the first focusing operation and the second focusing operation are controlled only by the elapsed time in order to control the focusing operation and the second focusing operation, the switching intention of the actual focusing operation is more finely defined. Corresponding switching control can be performed.

  In the imaging apparatus according to the present invention, even after the second focusing operation is started after the first focusing operation is shifted to the second focusing operation, before the second focusing operation is completed. When a shooting execution instruction is input, it is preferable to return to the first focusing operation completion state before shifting to the second focusing operation and execute shooting.

  That is, in the imaging apparatus according to the present invention, the control unit performs the second focusing operation when the execution instruction is input to the execution signal input unit before completion of the second focusing operation. Control may be performed so that the shooting operation is executed after stopping and returning to the completion state of the first focusing operation.

  According to the imaging apparatus configured in this way, even if the transition to the second focusing operation with high focusing accuracy is performed once, the execution of shooting is input before the second focusing operation is completed. When waiting for completion of the second focusing operation, there is a possibility that the shooting timing will be lost, but by returning to the first focusing operation completion state before the second focusing operation is shifted, shooting is immediately performed. Can be performed, and the possibility of missing the imaging timing can be reduced.

  In the imaging device according to the present invention, even after the second focusing operation is started after the first focusing operation is shifted to the second focusing operation, before the second focusing operation is completed. When a shooting execution instruction is input, it is necessary to return to the first focusing operation completion state before shifting to the second focusing operation, or to continue until the second focusing operation is completed. It is preferable to perform shooting after selecting according to the above.

  That is, in the imaging apparatus according to the present invention, the control unit performs the second focusing operation when the execution instruction is input to the execution signal input unit before completion of the second focusing operation. Compare the time required to stop and return to the completion state of the first focusing operation with the estimated time required to complete the operation after continuing the second focusing operation. Of these, it is only necessary to select and execute the operation that is completed in a short time, and then control to execute the photographing operation.

  According to the imaging apparatus configured as described above, for example, even when the transition to the second focusing operation with high focusing accuracy is performed once, the execution of shooting is input before the completion of the second focusing operation. If you wait until the second focusing operation is completed or return to the first focusing operation completion state before the second focusing operation, compare the time required to reach the faster one. Since the selection is made, it is possible to reduce the possibility of missing the shooting timing and execute the shooting.

  As described above, according to the imaging device of the first aspect of the present invention, when the start signal is input to the start signal input unit, the control unit starts the first focusing operation with so-called time lag priority. Thus, preparation for shooting that can deal with a dynamic subject is started (for example, when the shutter release button is pressed, the shutter release button must be in the half-pressed position before reaching the full-pressed position (execution of shooting)). Since it passes, the control means starts a first focusing operation with a so-called time lag priority at the time when it passes through this half-pressed position, and preparation for photographing that can deal with a dynamic subject is started.

  Thereafter, depending on the state such as whether the start signal is input to the start signal input means, whether the execution signal is input to the execution signal input means, and the elapsed time by the time measuring means, the control means, In order to control the first focusing operation and the second focusing operation, compared with the case where the first focusing operation and the second focusing operation are simply controlled only by the elapsed time, the intention of switching the actual focusing operation is More precise switching control can be performed (for example, the state of pressing the shutter release button, that is, whether the shutter release button is maintained at the half-pressed position or fully pressed down, and the elapsed time by the time measuring means) Therefore, since the control means controls the first focusing operation and the second focusing operation, compared with the case where the first focusing operation and the second focusing operation are controlled only by the elapsed time. Of the switching 換意 view of the focusing operation can be performed more finely the corresponding switching control).

  In addition, the second focusing operation is not inadvertently moved, and the first focusing operation can be performed at any time in a state where the first focusing operation is completed, that is, a dynamic subject is tracked and in focus. it can.

  Further, if the first focusing operation is not completed even after a predetermined reference time has elapsed from the start of the first focusing operation, the position of the imaging optical system or the imaging means at the start of the first focusing operation is in-focus. It is considered that there is an intention not to rush to release the shutter because the photographing execution operation has not been performed at the time when the reference time has elapsed, and thus the focusing accuracy is high. By performing control to switch to the second focusing operation, it is possible to execute a shooting operation in accordance with the user's intention.

  In addition, since the focus position of the imaging optical system or the imaging means by the first focusing operation becomes the start position of the second focusing operation, the evaluation is performed over the entire stroke of the imaging optical system or the imaging means (of the focusing position). (Search scanning) does not need to be performed, and the time from the start of the second focusing operation to the focusing can be increased compared to the case where the entire stroke is evaluated.

  According to the imaging device of the second aspect of the present invention, in accordance with the intention of the user who wants to shoot at a high speed, shooting is performed in a state of being focused at a high speed by the first focusing operation. can do.

  According to the imaging apparatus of the third aspect of the present invention, the first focusing means can perform the first focusing operation because the so-called normal focus position is set as the focus target position.

  In addition, since the position (ordinary focus position) of the imaging optical system or the imaging means at the time when the first focusing operation is completed becomes the start position of the second focusing operation, evaluation is performed over the entire stroke of the imaging optical system or imaging means. There is no need to perform (focus position search scanning), and the time from the start of the second focusing operation to focusing can be increased compared to the case of evaluating over the entire stroke.

  Further, according to the imaging device of the fourth aspect of the present invention, when the shutter release button is pressed, the shutter release button always passes through the half-pressed position before reaching the full-pressed position (shooting execution). At the point of passing the half-pressed position, the control means starts a first focusing operation with so-called time lag priority, and preparation for photographing that can deal with a dynamic subject is started.

  Thereafter, the control means determines whether or not the shutter release button is pressed, that is, whether the shutter release button is maintained at the half-pressed position or fully pressed down, and the elapsed time by the time measuring means. Compared with the case where the first focusing operation and the second focusing operation are controlled only by the elapsed time in order to control the focusing operation and the second focusing operation, the switching intention of the actual focusing operation is more finely defined. Corresponding switching control can be performed.

  Hereinafter, specific embodiments of an imaging apparatus according to the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram showing a digital camera 100 which is an embodiment of an imaging apparatus according to the present invention, and FIGS. 2 and 3 are flowcharts showing control of a focusing operation of the digital camera 100 shown in FIG.

  In the housing 10 of the digital camera 100 shown in FIG. 1, a camera operation unit 91, a display unit 92, a strobe light emitting unit 41, a lens barrel unit 20, a system controller 31, a shutter release button (release pressing unit) 61, and Various sensors and the like are accommodated.

  Here, the lens barrel unit 20 includes a photographing optical system 21, a CCD (imaging device) 24 on which an image of a subject incident through the photographing optical system 21 is projected, and the photographing optical system 21 and the CCD 24. An arranged low-pass filter (LPF) 23, a focus drive system 25 that moves the focus lens group 22 in the photographic optical system 21 in the optical axis direction, and a zoom lens group 28 in the photographic optical system 21 moves in the optical axis direction. A zoom drive system 26, a diaphragm 29 arranged between the zoom lens group 28 and the focus lens 22, and a shutter / diaphragm drive system 27 for adjusting the opening of the diaphragm 29.

  The CCD 24 is connected to an A / D converter 51 that digitizes the electrical signal output from the CCD 24, and the A / D converter 51 is connected to an image processing unit 52 that processes the digitized image signal. A digital signal subjected to signal processing in the image processing unit 52 is configured to be input to the system controller 80.

  The strobe light emitting unit 41 is connected to the system controller 80 via the strobe control unit 42.

  The shutter release button 61 includes a half-press detecting unit (start signal input means) 62 that detects a half-pressed state at the half-pressed position and the fully-pressed position of the button 61, and a fully-pressed position of the button 61. A full-press detection unit (execution signal input means) 63 for detecting the full-press state is provided.

  The half-press detection unit 62 and the full-press detection unit 63 are respectively connected to the system controller 80, and a half-pressed state detection signal (AF operation start instruction) and a full-pressed state detection signal (shooting execution instruction). Are input to the system controller 80.

  On the display unit 92, a visible image represented by a digital signal that has been subjected to signal processing in the image processing unit 52 and input to the system controller 80, various information set by the camera operation unit 91, and the like are displayed.

  The various sensors include a distance measuring sensor 31, a temperature sensor 71, a shake sensor 72, a posture sensor 73, and the like. Depending on the temperature, the shake state, and the camera posture detected by the temperature sensor 71, the shake sensor 72, and the posture sensor 73. Thus, the system controller 80 performs various correction processes on the input digital signal.

  The distance measuring sensor 31 is a sensor for obtaining a distance to a subject for an external light AF operation described later, and is connected to the system controller 80 via the distance measuring sensor control unit 32.

  A memory group 85 is connected to the system controller 80. The memory group 85 stores smart media and compact flash (removable from the housing 10 in a state where digital signals representing captured images are stored). A memory such as a registered trademark is also included.

  In addition, in the memory group 85, setting information set by the camera operation unit 91, flash memory that temporarily stores information sent from the system controller 80 so as to be rewritable, and information that cannot be rewritten are written. ROM is also included.

  In the ROM, a first reference time t1 (for example, t1 = 100 msec) serving as a reference for determining whether or not the shutter release button 61 is pressed at once for AF switching control to be described later, and the first reference time. A second reference time t2 that is shorter than t1 is stored in advance.

  Further, the system controller 80 includes an external light AF unit 81, a CCDAF unit 82, an AF control unit 83, and a timer 84.

  Here, the external light AF unit 81 focuses so as to move the focus lens group 22 to a focus position corresponding to the distance to the subject input from the distance sensor 31 via the distance sensor control unit 32. An AF unit that controls the driving unit 25.

  The outside light AF unit 81 controls the focus driving unit 25 so that the focus lens group 22 is moved to the normal focus position when the distance to the subject by the distance measuring sensor 31 cannot be measured appropriately. To do.

  On the other hand, the CCDAF unit 82 sequentially evaluates the digital signal projected onto the CCD 24 through the focus lens group 22 and the LPF 23 and input to the system controller 80 while moving the focus lens group 22, and based on this evaluation. The AF unit controls the focus driving unit 25 so that the focus lens group 22 is stopped at the in-focus position.

  The timer 84 measures the elapsed time after the half-pressed state of the shutter release button 61 detected by the half-press detection unit 62 is detected.

  The AF control unit 83 detects the half-pressed state by the half-press detecting unit 62 of the shutter release button 61, detects the fully-pressed state by the full-press detecting unit 63, the elapsed time measured by the timer 84, and the half-pressed state detection. In response to the subsequent detection of the half-pressed state and the detection of the fully-pressed state, the external light AF unit 81 performs the external light AF operation (first focusing operation) and the CCDAF unit 82 performs the CCDAF operation (second focusing operation). Control to switch is performed.

  Specific AF switching control of the AF control unit 83 is as follows.

  First, when an AF operation start instruction is input from the half-press detection unit 62, the external light AF operation is started.

  At this time, the operation of the timer 84 is also started, and the elapsed time from the AF operation start instruction is also counted.

  The external light AF operation is completed before the elapsed time t of the timer 84 reaches the preset first reference time t1, and when the external light AF operation is completed, the shutter release button 61 is pressed halfway. When the full-pressed state is not changed from the pressed state to the fully-pressed state, the external light is detected until the fully-pressed state is detected in the period from the completion of the external light AF operation until the elapsed time t reaches the first reference time t1. Control is performed to maintain the completion state of the AF operation.

  Further, when the full-press state is not detected during the period from the completion of the external light AF operation until the elapsed time t reaches the first reference time t1, the CCDAF unit 82 switches to the CCDAF operation.

  When this switching is performed, the stop position of the focus lens group 22 when the external light AF operation is completed (the in-focus position by the external light AF operation) is temporarily stored in the flash memory of the memory 85.

  Further, after the switch to the CCDAF operation and before the completion of the CCDAF operation, when the fully-pressed state is detected, the CCDAF operation is stopped and the external light AF operation temporarily stored in the flash memory is combined. The focus position is read, and the operation is switched to the external light AF operation so that the focus lens group 22 is moved to the focus position, and the photographing operation is executed after the movement is completed.

  On the other hand, when the fully pressed state is detected during the period from the completion of the first external light AF operation until the elapsed time t reaches the first reference time t1, the focus position at the completion of the external light AF operation is detected. Execute the shooting operation.

Further, prior to the first outside light AF operation is completed, if the elapsed time t has reached the first Criterion time t1 which is set in advance, as an operation start position focus position due to external light AF operation, CCDAF operation Switch to.

  When the external light AF unit 81 controls the focus driving unit 25 so as to move the focus lens group 22 to the normal focus position, after the external light AF operation is completed regardless of the elapsed time t. The CCDAF operation is controlled to start from the position of the focus lens when the operation is completed.

  Next, the operation of the digital camera 100 according to the present embodiment will be described with reference to the flowchart shown in FIG.

  First, the user of the digital camera 100 switches on a power supply (not shown) of the digital camera 100 to prepare for photographing (# 1).

  Next, the photographic optical system 21 is directed toward a subject not shown, and the shutter release button 61 is pressed to perform photographing.

  In order to zoom in on the subject as necessary, the camera operation unit 91 is operated, the zoom drive system 26 is controlled by the system controller 80, and the zoom lens group 28 can be driven by the zoom drive system 26. That's fine.

  Here, when the shutter release button 61 is pressed to the half-pressed position (# 2), the half-press detector 62 detects that the shutter release button 61 has been pressed to the half-pressed position, and starts the AF operation. A start signal indicating an instruction is output to the system controller 80.

  The system controller 80 inputs the input start signal to the AF control unit 83 and the timer 84, and the timer 84 starts counting elapsed time (# 3).

  At the same time, the system controller 80 sets the quick-push flag and the distance measurement flag to 0 (zero) and stores them in the flash memory (# 3).

  The quick-push flag is a flag for identifying whether or not the shutter release button 61 is pushed down to the full-press position at once. A value of 0 indicates that the shutter release button 61 is not pressed at a stroke and is an initial value. It represents that.

  On the other hand, the distance measurement flag is a flag for identifying whether or not the distance measurement by the distance measurement sensor 31 has been appropriately performed, and the value 0 represents that the distance measurement has been appropriately performed and is an initial value. 1 indicates that the distance measurement was not properly performed.

  Further, the AF control unit 83 to which the start signal is input controls the external light AF unit 81 so that the external light AF operation is performed.

  With this control, the external light AF unit 81 controls the distance sensor control unit 32 to operate the distance sensor 31.

  Further, simultaneously with the control to the distance measuring sensor control unit 32, the strobe control unit 42 is controlled so that the strobe light emitting unit 41 emits strobe light as external light for distance measurement.

  The subject that has received the strobe light emits the reflected light, and the reflected light is input to the distance measuring sensor 31, and the distance measuring sensor control unit 32 calculates the distance to the subject based on the principle of triangulation.

  The distance to the subject is input to the external light AF unit 81.

  On the other hand, if the subject has a repetitive pattern that cannot be calculated properly by the principle of triangulation, distance measurement may not be performed properly. In this case, the distance sensor control unit A ranging NG signal from 32 is input to the external light AF unit 81.

  Here, the external light AF unit 81 determines whether or not the distance measurement is appropriately performed (# 4).

  When the distance measurement is appropriately performed, the external light AF unit 81 uses an LUT (reference table) stored in the ROM in which the distance to the subject and the in-focus position of the focus lens group 22 are associated with each other in advance. With reference to this, the in-focus position of the focus lens group 22 corresponding to the input distance is obtained.

  Then, the external light AF unit 81 outputs a command to the focus drive system 25 so as to move the focus lens group 22 to the obtained in-focus position (# 5).

  The focus drive system 25 starts driving to move the focus lens group 22 to the commanded focus position (# 8).

  On the other hand, when the distance measurement is not properly performed, the external light AF unit 81 rewrites the value of the distance measurement flag stored in the flash memory to 1 (# 6) and is always stored in the ROM. The focus position is uniformly set as the focus position of the focus lens group 22, and a command is output to the focus drive system 25 so as to move the focus lens group 22 to the set normal focus position (# 7).

  The focus drive system 25 starts driving to move the focus lens group 22 to the normal focus position that is the commanded focus position (# 8).

  The above is the operation when the shutter release button 61 is pressed down to the half-pressed position. As described above, the digital camera 100 according to the present embodiment, when the shutter release button 61 is pressed down to the half-pressed position, Regardless of whether or not the shutter release button 61 has been pressed all the way to the fully pressed position, the external light AF operation is first started.

  Next, an operation according to whether or not the shutter release button 61 has been pressed all the way to the fully pressed position will be described.

  First, it is determined whether or not the shutter release button 61 has reached the fully pressed position (# 9).

  That is, when the shutter release button 61 is pressed down to the fully-pressed position, the full-press detecting unit 63 detects that the shutter release button 61 has been pressed down to the fully-pressed position, and an execution signal indicating an execution instruction for shooting. Is output to the system controller 80.

  Then, the input of this execution signal causes the AF controller 83 of the system controller to determine that the full-press position has been reached, and rewrites the value of the quick-press flag stored in the flash memory to 1.

  Regardless of whether or not the shutter release button 61 has reached the fully-pressed position, the AF control unit 83 refers to the time (elapsed time t) of the timer 84 and the second reference time stored in the ROM. It is determined whether or not t2 is exceeded (# 11).

  Here, when the elapsed time t of the timer 84 exceeds the second reference time t2, when the second reference time t2 or more has not elapsed while being pressed from the half-pressed position to the full-pressed position, It is determined whether or not the light AF operation is completed (# 14).

  When the external light AF operation is not completed, the process returns to step 9 (# 9), where it is determined whether full press is detected (# 9), and whether the elapsed time t exceeds the second reference time t2. The routine of determination (# 11) and determination of whether or not the external light AF operation is completed (# 14) is repeated.

  During this time, if full press is detected, the value of the quick press flag is rewritten to 1 (# 10), and if the elapsed time t exceeds the second reference time t2, the value of the quick press flag is 1 or not. That is, it is determined whether or not full press is detected before the external light AF operation is completed (# 12).

  When the value of the quick-push flag is not 1, that is, when full-press is not detected, the focus position set in the external light AF operation (the position of the focus lens group 22 when the external light AF operation is completed). Is set as the operation start position of the focus lens group 22 by the CCDAF operation and stored in the flash memory (# 13).

  The above routine ends when the external light AF operation is completed (# 14), and the focus position of the focus lens group 22 at the completion of the operation is temporarily stored in the flash memory.

  Subsequently, the AF control unit 83 determines whether or not the value of the quick-press flag is 1 (# 15).

  When the value of the quick-push flag is 1, the full-press is detected (# 10) before the external light AF operation is completed (# 14), and the external light AF operation is completed. The AF control unit 83 performs control so that the photographing operation is executed at the focus position of the focus lens group 22 (# 27), and the image of the subject projected on the CCD 24 is photoelectrically converted and is converted by the A / D converter 51. The signal is converted into a digital signal, subjected to predetermined signal processing by the image processing unit 52, input to the system controller 80, stored as a digital image signal in a removable memory, and the process returns to step 2 (# 2).

  On the other hand, when the value of the quick-press flag is not 1, since the full-press has not been detected yet, the AF control unit 83 checks the value of the distance measurement flag (# 18).

  When the value of the distance measurement flag is not 1, that is, when appropriate distance measurement is performed, the AF control unit 83 determines whether or not the elapsed time t exceeds the first reference time t1 ( # 23).

  Further, if the elapsed time t does not exceed the first reference time t1, it means that the shutter release button 61 is no longer determined to be pressed all the time, and the AF control unit 83 further controls the shutter release button 61. Confirms whether or not the half-pressed position is detected (# 25).

  If the half-pressed position has not been detected, the shutter release button 61 has not been pressed at all, so the photographing preparation operation itself has been stopped, and the process returns to step 2 (# 2).

  On the other hand, if the half-pressed position is detected, the AF control unit 83 further checks whether full-press is detected (# 26).

  When the fully-pressed state is detected, the photographing operation is executed, and the AF control unit 83 is the AF control unit 83 at the in-focus position of the focus lens group 22 when the external light AF operation is completed. Is controlled so as to execute the photographing operation (# 27), the image of the subject projected on the CCD 24 is photoelectrically converted, converted into a digital signal by the A / D converter 51, and predetermined signal processing by the image processor 52. Is input to the system controller 80, stored as a digital image signal in a removable memory, and the process returns to step 2 (# 2).

  On the other hand, when the fully-pressed state is not detected, the half-pressed state is maintained and the photographing operation is not executed, so the process returns to step 23 (# 23), and the elapsed time t is the first reference time t1. The routine of step 23 (# 23), step 25 (# 25), and step 28 (# 28) is repeated until the value exceeds.

  When the elapsed time t exceeds the first reference time t1 (# 23), the focusing position of the focus lens group 22 in the external light AF operation in which the operation has already been completed is set as the operation start position, and the focusing accuracy is high. The AF control unit 83 controls the external light AF unit 81 and the CCDAF unit 82 so as to start the CCDAF operation (# 24).

  Under the control of the AF control unit 83, the CCDAF unit 82 controls the focus drive system 25 so as to start driving the focus lens group 22 by the CCDAF operation.

  The AF control unit 83 repeats the determination (# 21) whether or not the shutter release button 61 has been fully pressed until the CCDAF operation is completed (# 18).

  Here, if the shutter release button 61 is fully pressed before the CCDAF operation is completed (# 21), the AF control unit 83 stops the CCDAF operation without waiting for the completion of the CCDAF operation. In addition to controlling the CCDAF unit 82, the outside light AF unit 81 is controlled so as to move the focus lens group 22 to the in-focus position when the outside light AF operation is temporarily stored in the flash memory (# 22). ).

  As a result, the external light AF unit 81 controls the focus driving system 25 to move the focus lens group 22 to the temporarily stored in-focus position, and after the movement of the focus lens group 22 is completed, the AF control unit 83. Is controlled to execute a photographing operation (# 27), the image of the subject projected on the CCD 24 is photoelectrically converted and converted into a digital signal by the A / D converter 51, and a predetermined signal is output by the image processor 52. Processing is performed, input to the system controller 80, stored as a digital image signal in a removable memory, and the process returns to step 2 (# 2).

  When the value of the distance measurement flag in step 16 (# 16) is 1, since the appropriate distance measurement is not performed, the focus position of the focus lens group 22 when the external light AF operation is completed is always normal. Since it is the focal position, the reliability of the focusing accuracy is not high.

  Therefore, the AF control unit 83 performs the CCDAF operation over the entire movable range of the focus lens group 22 regardless of the focus position of the focus lens group 22 when the external light AF operation is completed. Is controlled (# 17).

  However, if the full release of the shutter release button 61 is detected before the CCDAF operation is completed (# 21), the AF control unit 83 stops the CCDAF operation without waiting for the completion of the CCDAF operation. The CCD AF unit 82 is controlled, and the outside light AF unit 81 is controlled so that the focus lens group 22 is moved to a focus position (ordinary focus position) when the outside light AF operation is temporarily stored in the flash memory. (# 22), and processing for giving priority to the in-focus speed is performed.

  As a result, the external light AF unit 81 controls the focus driving system 25 to move the focus lens group 22 to the temporarily stored in-focus position, and after the movement of the focus lens group 22 is completed, the AF control unit 83. Is controlled to execute a photographing operation (# 27), the image of the subject projected on the CCD 24 is photoelectrically converted and converted into a digital signal by the A / D converter 51, and a predetermined signal is output by the image processor 52. Processing is performed, input to the system controller 80, stored as a digital image signal in a removable memory, and the process returns to step 2 (# 2).

  On the other hand, if full-press of the shutter release button 61 is not detected before the CCDAF operation is completed (# 21), the AF control unit 83 indicates that the shutter release button 61 is halfway after the CCDAF operation is completed (# 18). It is confirmed whether or not the pressing position is detected (# 19).

  If the half-pressed position has not been detected, the shutter release button 61 has not been pressed at all, so the photographing preparation operation itself has been stopped, and the process returns to step 2 (# 2).

  On the other hand, when the half-pressed position is detected, the AF control unit 83 further checks whether or not full-press is detected (# 20).

  When the fully-pressed state is detected, the shooting operation is executed, and the AF control unit 83 takes a picture at the in-focus position of the focus lens group 22 when the CCDAF operation is completed. The image of the subject projected on the CCD 24 is photoelectrically converted, converted into a digital signal by the A / D converter 51, and subjected to predetermined signal processing by the image processing unit 52 (# 27). Then, it is input to the system controller 80, stored as a digital image signal in a removable memory, and the process returns to step 2 (# 2).

  As described above, according to the digital camera 100 according to the present embodiment, the AF control unit 83 performs the external light AF operation by the external light AF unit 81 according to the pressing state of the shutter release button 61 and the elapsed time t. In order to control the CCDAF operation by the CCDAF unit 82, the user can perform the switching control of the photographing operation and the AF operation corresponding to the user more finely than when the AF operation is controlled based only on the elapsed time t. it can.

  In Step 2 (# 2), immediately after the half-press of the shutter release button 61 is detected, the elapsed time t is started to be measured in Step 3 (# 3), and the external AF operation is started in Step 14 (# 14). Even after the completion, until the elapsed time t reaches the first reference time t1, the routine of step 23 (# 23), step 25 (# 25), and step 26 (# 26) is repeated, so that the external AF operation is performed. Even if the external AF operation is completed unexpectedly quickly, it is possible to correctly detect whether or not the shutter release button 61 has been pressed at once, without shifting to the CCDAF operation only by the completion. The user's shooting operation can be appropriately reflected in the AF operation.

  Further, if the full press is not detected even after the elapsed time t has passed the first reference time t1, it is determined that only the half press is made and the process proceeds to the CCDAF operation in step 24 (# 24). An operation that appropriately reflects the intention of the focus lock (half-pressing operation of the shutter release button 61) can be performed, and a CCDAF operation with high focusing accuracy can be performed.

  Since the digital camera 100 according to the present embodiment assumes a so-called hybrid AF (HBAF) operation in which an external light AF operation and a CCDAF operation are combined, the scanning range of the focus lens group 22 during the CCDAF operation is It is assumed that only the vicinity of the focus position when the external AF operation is completed is scanned instead of the entire movable range (# 24). However, as in step 17 (# 17), the entire movable range is scanned. May be.

  On the other hand, if the full press is detected before the first reference time t1, the shooting operation is immediately started (# 27) according to the determination in step 26 (# 26). It is possible to make the intention of executing the shooting appropriately reflect the external AF operation which is a high-speed AF operation.

  In the routine of step 23 (# 23), step 25 (# 25), and step 26 (# 26), when the half-pressed state is released, the shooting preparation operation itself is stopped, Returning to Step 2 (# 2), the input of the shutter release button 61 is awaited, and in this respect as well, an operation appropriately reflecting the usage status can be performed.

  In addition, after shifting to the CCDAF operation (# 24, # 17), for example, when a user wants to take a smiling face of a child instantly, if the user waits for the completion of the CCDAF operation, the user misses a photo opportunity. In the event that the shutter release button 61 is fully pressed to perform the shooting execution operation, the CCDAF operation is stopped (# 22), and the focus lens group 22 is controlled to return to the in-focus position when the external AF operation is completed. The high speed of the external AF operation can be utilized more effectively.

  Further, as in the routine shown in FIG. 4, the remaining time t4 until the CCDAF operation is completed is compared with the time t3 for driving the focus lens group 22 from the current position to the in-focus position at the completion of the external AF operation. By the control for selecting the earlier one, it is always possible to execute the shooting first.

  Further, when full press is detected during the external AF operation that is executed first, the determination is made in step 9 (# 9), and the value of the quick press flag is set to 1 in step 10 (# 10). When the value of the quick-push flag is 1 (# 15), after the external AF operation is completed, the operation immediately shifts to the shooting execution operation (# 17). Therefore, an appropriate operation corresponding to the user's quick-push operation is performed. Can be performed.

  When the distance measurement in the external AF operation is NG (# 4), that is, for example, the distance measurement sensor control unit 32 is in the passive AF operation and the focus of the distance measurement sensor 31 is low because the contrast of the subject is low. Controls to immediately shift to CCDAF operation giving priority to focusing performance when it cannot be performed properly or when the subject is a repetitive pattern and there is a possibility of calculating an incorrect focusing position. It is also possible to adopt a configuration that does this.

  However, in such a configuration, although the user has performed a quick push operation, the CCDAF operation has been performed, so that it takes a long time to perform shooting, contrary to the user's intention of a quick push. There is a risk of missing the shutter chance.

  For this reason, the digital camera 100 according to the present embodiment consistently recognizes that the user's pressing operation is a time lag priority intention even if the distance measurement in the external AF operation is NG. By setting the normal focus position as the target position (# 7), the speed-priority outside light AF operation can be continued.

  Further, even if the external light AF operation is continued and completed in this way, the possibility that the normal focus position is an appropriate in-focus position is not necessarily high.

  Therefore, it is stored whether the distance measurement of the external AF operation is OK or NG (# 6), and in the case of NG (# 16), it waits for the elapsed time t to reach the first reference time t1 (# 23). In other words, the control (# 17) for shifting to the CCDAF operation over the entire movable range of the focus lens group 22 can start the CCDAF operation with high focusing accuracy as early as possible and suppress the out-of-focus blur as much as possible.

  In addition, when a long time that cannot be pressed at a stroke has elapsed from the start to the completion of the external AF operation, switching to the CCDAF operation is performed when the elapsed time t reaches the second reference time t2. It is also considered preferable.

  However, when such switching control is simply performed, the movable range in which the focus lens group 22 is moved toward the in-focus position obtained by the external AF operation is scanned again in detail by the CCDAF operation after the AF operation is switched. Thus, although the situation varies depending on the moving direction of the focus lens group 22 at the start of driving, scanning in this range is likely to be wasted.

  On the other hand, since the true focus position does not necessarily exist near the focus position obtained by the external light AF operation, only the vicinity of the focus position obtained by the external light AF operation is scanned by the CCDAF operation. Is also not preferred.

  For this reason, in the digital camera 100 of this embodiment, by setting the position of the focus lens group 22 at the time when the second reference time t2 has elapsed as the start position of the CCDAF operation (# 13), wasted driving time is reduced. It is possible to achieve the fastest AF operation completion without spending money.

  The second reference time t2 may be set as a value equal to the first reference time t1, and in this case, the constant stored in the ROM can be reduced, and the elapsed time t determination subroutine is the same. Therefore, the types of processing flows can be reduced.

  Also, in the digital camera 100 according to the above embodiment, when the shutter release button 61 is fully pressed (# 21) before the CCDAF operation is completed (# 18), the AF control unit 83 uniformly performs CCDAF. Although the operation is stopped, the external light AF unit 81 and the CCDAF unit 82 are controlled so as to move the focus lens group 22 to the in-focus position by the external light AF operation stored in the flash memory. The imaging apparatus is not limited to this form.

  In other words, from the viewpoint of completing the AF operation faster when the shutter release button 61 is fully pressed, the time required to complete the CCDAF operation by continuing the CCDAF operation that has been performed halfway is increased. Switch to the light AF operation and compare the time required to move the focus lens group 22 to the in-focus position when the external light AF operation is temporarily stored in the flash memory, and select the shorter one It is preferable to do this.

  Accordingly, the time t4 required to complete the CCDAF operation is moved from the position of the focus lens group 22 moved by the CCDAF operation to the in-focus position by the external light AF operation when the full press is detected. When it is shorter than the time t3 required for the operation (t3> t4), the AF control unit 83 may control the CCDAF unit 82 so as to continue the CCDAF operation.

  That is, in the processing flow of FIG. 3, the routine of step 18 (# 18), step 21 (# 21), and step 22 (# 22) is replaced with step 18 (# 18) and step 21 (# 21) shown in FIG. ), Step 28 (# 28) and Step 22 (# 22) may be replaced.

  In this case, the time t3 required to move the focus lens group 22 from the position of the focus lens group 22 moved by the CCDAF operation to the in-focus position by the external light AF operation at the time when the full press is detected is the movement distance and Although it can be calculated based on the driving speed of the focus lens drive system 25 by the external light AF operation of the external light AF unit 81 and the switching time from the CCDAF operation to the external light AF operation, the time required to complete the CCDAF operation t4 cannot be accurately calculated because the in-focus position at the completion of the CCDAF operation is unknown.

  However, based on the remaining stroke of the movable range of the focus lens group 22 and the transition of the increase rate or the decrease rate of the evaluation value of the image signal that has already been performed before full pressing is detected, the result at the time of completion of the CCDAF operation is determined. The focal position can be predicted to some extent, and the processing flow shown in FIG. 4 is realized by providing the AF control unit 83 with such a prediction unit and the comparison unit between the times t3 and t4. Is possible.

  Note that the imaging apparatus of the present invention is not limited to the above-described embodiment, and it is needless to say that various forms can be adopted within the scope of the claims.

  For example, the focus lens group 22 is fixedly arranged, the CCD 24 can be moved in the optical axis direction of the photographing optical system 21, and the CCD 24 is driven instead of the focus drive system 25 driving the focus lens group 22. It is good.

  The focus drive system 25 may drive not only the focus lens group 22 but also the entire photographic optical system 21.

It is a block diagram which shows the digital camera which is one Embodiment about the imaging device which concerns on this invention. 4 is a flowchart (part 1) illustrating AF control and shooting execution processing in the digital camera illustrated in FIG. 4 is a flowchart (part 2) illustrating AF control and shooting execution processing in the digital camera illustrated in FIG. 1. It is a part of flowchart which shows the routine of another form about a part of routine among the flowcharts shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Case 20 Lens barrel unit 21 Shooting optical system 22 Focus lens group 23 Low pass filter 24 CCD (imaging device)
25 Focus drive system 26 Zoom drive system 27 Shutter / aperture drive system 28 Zoom lens group 31 Distance sensor 32 Distance sensor control unit 41 Strobe light emission unit 42 Strobe control unit 51 A / D converter 52 Image processing unit 61 Shutter release button ( (Release pressing part)
62 half-press detection unit 63 full-press detection unit 80 system controller 81 external light AF unit 82 CCDAF unit 83 AF control unit 84 timer 85 memory group 91 camera operation unit 92 display unit 100 digital camera

Claims (3)

Imaging means for converting the projected image into an image signal and outputting the image signal;
An imaging optical system for projecting an image of a subject on the imaging means;
A distance value is obtained by measuring a distance to the subject, and at least one of the imaging optical system and at least one of the imaging means is relatively moved to a first in-focus position corresponding to the distance value. First focusing means for performing a first focusing operation;
While sequentially moving at least one part of the photographing optical system and at least one of the imaging means, the sequential image signals obtained through the photographing optical system are evaluated, and a second combination based on the evaluation is performed. A second focusing means for performing a second focusing operation for stopping at least one of the imaging optical system and at least one of the imaging means at a focal position;
Control means for controlling switching between the first focusing operation and the second focusing operation;
Start signal input means for inputting an instruction to start focusing operation;
An execution signal input means for inputting an execution instruction of the photographing operation;
In an imaging apparatus provided with a time measuring unit that measures an elapsed time after the start instruction of the focusing operation is input,
When the start instruction is input to the start signal input unit, the control unit starts the first focusing operation of the two focusing operations, and sets the elapsed time to a preset reference time. When the first focusing operation is completed before the first focusing operation is completed, the start instruction input to the start signal input means is maintained at the time when the first focusing operation is completed, and the execution signal input means It said execution instruction if not inputted, the period from completion of the first Go focusing operation until the elapsed time reaches the reference time, so as to maintain the completion status of the first Go focusing operation in and control to,
If the execution instruction is input to the execution signal input means from the time when the first focusing operation is completed until the elapsed time reaches the reference time, the completion state of the first focusing operation is set. Control to execute the shooting operation while maintaining
The elapsed when the time reaches the criteria time, imaging and controlling from the first focus position to initiate the second Go focusing operation device. The first focusing means sets the normal focus position as the first focus position when the distance value cannot be obtained with a preset accuracy;
The control means performs control so as to start the second focusing operation from the position at the time when the first focusing operation is completed after the completion of the first focusing operation, regardless of the elapsed time. The imaging apparatus according to claim 1 . A shutter release button
The start signal input means and the execution signal input means are both shutter release buttons, and the start instruction is input at the half-pressed position of the shutter release button, and the execution instruction is input at the full-pressed position of the shutter release button. The imaging apparatus according to claim 1, wherein the image pickup device is input.

Images