JP2007121504A - Focus detection apparatus and method, and imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a focus detection apparatus capable of sufficiently securing focus accuracy in various photographing purposes (setting of conditions such as photographing resolution, a compression ratio, moving image recording/still image recording, and HD/SD recording modes) and capable of quickly detecting a focused point. <P>SOLUTION: The focus detecting apparatus comprises: a first focus detection means for detecting a focused point by using an evaluation signal expressing the focus state of an imaging optical system based on an imaging signal obtained by photoelectric converting an object image by an imaging means; a second focus detection means for detecting the focused point on the basis of a detection signal different from the evaluation signal; and a selection means for selecting first control for controlling the detection of the focused point so that the focused point is detected by using at least the second focus detection means or second control different from the first control to control focus detection so that the focused point is detected by using the first focus detection means and the second focus detection means in accordance with a recording mode of an image obtained by the imaging means. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention generally relates to a focus detection apparatus and method, and more particularly to a focus detection apparatus and method for detecting a focus state of an imaging optical system using a plurality of focus detection means.

  With the widespread use of digital cameras, video cameras, and the like, higher quality and improved operability are increasingly required for such imaging apparatuses. In particular, high accuracy and high speed of focus detection (autofocus (AF)) for detecting the in-focus state of the imaging lens are desired.

  As an example of focus detection, a TTL autofocus method (hereinafter referred to as “imaging”), which conventionally extracts a high-frequency component of an imaging signal and focuses a position where the high-frequency component is maximized (the peak of a high-frequency component (mountain)). Signal AF ")). The imaging signal AF does not require a mechanical member or the like for detecting the focus, can realize low cost, and does not change with time of the mechanical member. Further, the imaging signal AF has a feature of high accuracy in order to detect a focus by the imaging signal. In particular, in imaging using a high-pixel imaging device, since the focus accuracy is extremely strict, the imaging signal AF that is not affected by the change with time of the mechanical member is very effective.

  In order to detect the apex of the high-frequency component (mountain), that is, the focal point, the imaging signal AF needs to scan the entire region to grasp the shape of the mountain, or perform a so-called mountain climbing operation. . When you scan the whole area and grasp the shape of a mountain, you can see the action of defocusing and matching, so even if it is good for still image shooting, it is unsightly when you are shooting video or previewing on the monitor There is a drawback. In addition, the hill-climbing operation is generally used in movie shooting and preview, but when starting from a lens position away from the focal point, the mountain shape starts from a flat position, so the direction of the peak of the mountain is It is difficult to determine where it is. If the direction of the apex of the mountain is wrong, it will cause an unsightly action such as going back to the opposite end of the apex direction and returning, and it will take a lot of time to focus.

  On the other hand, TTL using the infrared triangular focus detection method and pupil division phase difference detection method and autofocus of the direct direct focus detection method (hereinafter referred to as “direct focus detection AF”) can directly measure the focal length. Is possible. The direct focus detection AF does not require a scanning operation or a hill climbing operation to detect the position of the focal point, and can shorten the time until focusing (that is, detect the focused state at high speed).

  The direct focus detection AF requires a mechanical member or the like for detecting the focus, and detects the focus using a system different from the imaging system. Therefore, the direct focus detection AF has drawbacks such that an in-focus position includes an error due to a change with time or a temperature change, or a parallax occurs between the captured image and the focus detection position according to the distance. . In particular, in imaging using a high-pixel imaging device, a focus position error due to a change over time or a temperature change may be a fatal blur.

  Therefore, a hybrid AF that realizes high-speed and high-precision autofocus by combining the imaging signal AF and the direct focus detection AF has been proposed. In hybrid AF, as a method of selecting two AF methods, switching from direct focus detection AF to imaging signal AF by operating an imaging switch has been proposed (for example, see Patent Document 1). Also, Patent Document 1 proposes that the in-focus positions detected by the two AF methods are compared, and if the detection result differs by a predetermined value or more, either method is selected according to the conditions. .

  Further, after driving to the position of the front pin or the rear pin by a predetermined amount using the direct focus detection AF, switching to the imaging signal AF, and when the focus cannot be detected by the imaging signal AF, switching to the direct focus detection AF again. Has also been proposed (see, for example, Patent Document 2).

It has also been proposed to detect the focus using the imaging signal AF when a high-frequency component is detected by controlling the direction and speed of the focus using a phase difference method when the focus is greatly deviated (for example, (See Patent Document 3).
JP 2001-264622 A JP 2001-141984 Japanese Patent Laid-Open No. 3-81713

  Recent image pickup devices are equipped with high-resolution, high-pixel image sensors, and can record high-definition video images (HD) on a recording medium. Depending on the image-recording setting (recording mode), the same image-capturing device can be used. The device can also record normal resolution (SD) moving images. Furthermore, it is possible to record a moving image that emphasizes handling at a lower resolution or a lower compression rate on a memory card or the like. In addition to moving images, still images with various resolutions and compression rates can be recorded, and the imaging apparatus can be used for various photographing applications.

  Considering the AF of such a multifunctional imaging device, even if the same imaging device is used, the required focusing accuracy and focus detection speed differ depending on the shooting application. When an optimum hybrid AF is configured by combining the imaging signal AF and the direct focus detection AF, generally, when the imaging signal AF is used intensively, it takes time until focusing, but it is possible to ensure focusing accuracy. Become. On the other hand, when the direct focus detection AF is used intensively, it does not take time until focusing, but it becomes difficult to ensure focusing accuracy. In other words, in the conventional technology, it has been impossible to achieve both a high accuracy and a high speed of focus detection in a balanced manner with respect to recent imaging apparatuses.

  Therefore, the present invention ensures sufficient focusing accuracy for various shooting applications (setting conditions such as shooting resolution, compression rate, moving image recording or still image recording, HD / SD recording mode, etc.) The purpose is to detect the focus at high speed.

  In order to achieve the above object, the technical feature of the present invention is that a detection signal different from an evaluation signal representing a focus state of an imaging optical system based on an imaging signal obtained by photoelectrically converting at least a subject image by an imaging means. The first control for detecting the focal point based on the detection signal, the detection of the focal point based on the detection signal different from the evaluation signal, and the detection of the focal point based on the detection of the focal point based on the evaluation signal. The second control to be performed is selected and executed according to an image recording mode obtained by the imaging means.

  Another technical feature of the present invention is that focusing is performed based on a detection signal that is different from an evaluation signal that represents a focus state of an imaging optical system based on an imaging signal obtained by photoelectrically converting a subject image by an imaging unit. From the detection of the in-focus based on a detection signal different from the evaluation signal according to the first control for detecting the detection, the degree of in-focus of the imaging optical system, and detecting the degree of in-focus. The second control for detecting the focal point by switching to the focal point detection based on the evaluation signal is selected and executed according to the recording mode of the image obtained by the imaging means.

  Another technical feature of the present invention is that focusing is performed based on a detection signal that is different from an evaluation signal that represents a focus state of an imaging optical system based on an imaging signal obtained by photoelectrically converting a subject image by an imaging unit. The first control for detecting the focal point based on the evaluation signal in the vicinity of the focal point, and the degree of focusing of the imaging optical system, after moving the imaging optical system to the focal point In accordance with the detected degree of focus, the focus detection is switched from the focus detection based on the detection signal different from the evaluation signal to the focus detection based on the evaluation signal. The second control to be performed is selected and executed according to an image recording mode obtained by the imaging means.

  Further objects and other features of the present invention will become apparent from the preferred embodiments described below with reference to the accompanying drawings.

  According to the present invention, sufficient focusing accuracy is ensured for various shooting applications (conditioning settings such as shooting resolution, compression ratio, moving image recording or still image recording, HD / SD recording mode, etc.) A focus detection technique capable of detecting the focus at high speed can be provided.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the accompanying drawings. In addition, in each figure, the same reference number is attached | subjected about the same member and the overlapping description is abbreviate | omitted.

  With reference to FIG. 1, the concept of the focus detection apparatus 100 as one aspect of the present invention will be described. FIG. 1 is a schematic block diagram showing a configuration of a focus detection apparatus 100 of the present invention. The focus detection apparatus 100 includes a direct focus detection unit 101, an imaging signal detection unit 102, a hill climbing control unit 103, a generation unit 104, a selection unit 105, a switch 106, a lens driving system 107, and an imaging record setting unit. 108.

  The direct focus detection unit 101 outputs a distance signal D as a detection result. In other words, the direct focus detection unit 101 performs the direct focus detection AF operation. The imaging signal detection unit 102 outputs an evaluation value FV of the imaging signal AF. In other words, the imaging signal detection unit 102 performs the operation of the imaging signal AF via the hill climbing control unit 103 described later. The hill climbing control unit 103 detects a focal point by a hill climbing operation using the evaluation value FV.

  The generation unit 104 generates the AF method selection reference signal IFA1 or IFA2 based on one or both of the distance signal D from the direct focus detection unit 101 and the imaging signal AF from the imaging signal detection unit 102.

  The selection unit 105 determines the AF method selection based on the AF method selection reference signal IFA1 or IFA2 from the AF method selection reference signal generation unit 104 and the setting signal RS from the imaging / recording setting unit 108. Further, the selection means 105 selects (switches) the direct focus detection AF or the imaging signal AF by switching the switch 106 and transmits it to the lens driving system 107.

  FIG. 2 is a schematic block diagram illustrating a configuration of the imaging apparatus 200 including the focus detection apparatus 100 illustrated in FIG. The imaging device 200 captures moving images and still images and records them on various media such as a tape, a solid-state memory, an optical disk, and a magnetic disk. The imaging device 200 is embodied by a video camera or a digital still camera, for example. The imaging apparatus 200 has a configuration in which units described later are connected via a bus BS. Each unit is controlled by the main control unit 251.

  The lens unit 201 includes a first fixed lens group 202, a zoom lens 211, a diaphragm 203, a second fixed lens group 221, and a focus lens 231. The lens unit 201 forms an image of light from the subject on the image sensor 241 via the optical member described above, and images the subject.

  The zoom control unit 213 drives the zoom lens 211 via the zoom motor (ZM) 212 based on the control of the main control unit 251.

  The image sensor 241 photoelectrically converts the formed image and outputs it to the image signal processing circuit 242. The imaging control unit 243 controls the imaging element 241 and the imaging signal processing circuit 242 with an imaging method according to imaging conditions such as imaging resolution, moving image shooting / still image shooting, and the like based on an instruction from the main control unit 251. The imaging signal processing circuit 242 adjusts the output from the imaging element 241 as an image signal based on the control of the imaging control unit 243, and outputs the imaging signal TVS to the AF signal processing circuit 234.

  The AF signal processing circuit 234 generates an FV signal (a signal corresponding to a predetermined frequency component) for controlling the mountain climbing operation and an IFA signal indicating the degree of focus, and inputs the generated signal to the focus control unit 233.

  On the other hand, the direct focus detection unit 230 detects two subject images (detection signals) formed on the phase difference detector 239 via the pupil division optical system 238. Specifically, the direct focus detection unit 230 detects the phase difference amount of the two images by the phase difference detector 239. Further, the direct focus detection unit 230 calculates a distance signal D to the subject from the phase difference amount of the two images and inputs it to the focus control unit 233.

  The focus control unit 233 generates a focus degree signal IFA2 (not shown) from the distance signal D from the direct focus detection unit 230 and the position of the focus lens 231. The focus control unit 233 drives the focus lens 231 via the focus motor (FM) 232 based on the distance signal D or the focus level signal IFA2 and the evaluation value FV or the focus level IFA of the imaging signal AF. Thereby, autofocus (AF) is realized.

  The image signal prepared by the imaging signal processing circuit 242 is temporarily stored in the RAM 254. The image compression / decompression circuit 253 compresses the image signal stored in the RAM 254 at a predetermined compression rate instructed from the main control unit, and stores the image recording medium 257 in a predetermined recording format (SD) instructed from the main control unit. Movie / HD movie / still image etc.). In addition, the image processing unit 252 reduces or enlarges the image signal stored in the RAM 254 to an optimum size, displays the image signal on the monitor display 250, and feeds back the captured image to the photographer in real time. Further, after imaging, the captured image can be confirmed by displaying the captured image on the monitor display 250 for a predetermined time.

  The image recording medium 257 may be a random access medium such as an optical disk, a hard disk, or a semiconductor memory (for example, a flash memory), or may be a sequential medium such as a magnetic tape. The image compression method in the image compression / decompression circuit 253 may be motion JPPEG or DV compression for a moving image, or may be a moving image compression method for compressing between frames such as MPEG or H264. When recording on a magnetic tape, for example, an SD image is compressed by a DV compression method that performs only intraframe (intrafield) compression, and an HD image is compressed by HDV using MPEG compression in order to increase the compression rate. A method may be used. For example, when an HD image is selected by an imaging / recording setting switch (to be described later), the HDV compression method is used, and when an SD image is set, the DV compression method is used.

  Although not shown, a plurality of types of image recording media 257 may be provided, and for example, a moving image may be recorded on a tape and a still image may be recorded on a flash memory in accordance with an imaging recording setting switch. Also, a high-resolution moving image may be recorded on a tape, and a low-resolution moving image may be recorded on a flash memory. Of course, a high-resolution moving image may be recorded on an optical disk or a hard disk, and a low-resolution moving image may be recorded on the flash memory 255.

  In this embodiment, the operation switch 256 includes a power switch, a zoom switch, a release switch, an ON / OFF switch of the monitor display 250, a switch of the imaging record setting unit 108, and the like. The power switch turns on / off the power of the imaging apparatus 200. The zoom switch instructs to drive the zoom lens 211. In the present embodiment, the release switch has a two-stage push configuration, and hereinafter, the first stage is referred to as a switch SW1, and the second stage is referred to as a switch SW2. In the case of still image shooting, the switch SW1 instructs to return from shooting standby and prepares to start shooting (for example, an instruction to start autofocus and metering), and the switch SW2 performs shooting and transfers to the image recording medium 257. Instructs the recording of images. In the case of moving image shooting, recording is started by operating switch SW2 once, and recording is stopped by operating switch SW2 again in the recording state. An ON / OFF switch of the monitor display 250 switches display or non-display of an image in a shooting state on the monitor display 250. The imaging / recording setting switch indicates whether to perform HD (high-definition) recording (image) or SD (normal TV) recording (image), whether to perform still image recording or moving image recording, and the recording compression rate. Instructions and recording resolution are given. Further, the imaging recording setting switch gives an instruction or the like as to whether to perform moving image shooting with a recording resolution lower than that of SD recording. That is, the recording mode is set.

  The power management unit 258 is connected to the battery 259, checks the power state of the battery 259, charges the battery 259, and performs power management.

  In such a configuration, when the imaging apparatus 200 is activated from the OFF state (becomes ON state), the program stored in the flash memory 255 is loaded into a part of the RAM 254. The main control unit 251 operates according to a program loaded in the RAM 254.

  Hereinafter, the AF signal processing circuit 234 and the focus control unit 233 will be described.

  FIG. 3 is a schematic block diagram showing a specific configuration of the AF signal processing circuit 234. Referring to FIG. 3, the image signal TVS from the image signal processing circuit 242 is extracted only in a part of the screen by one or a plurality of focus detection gates 301, and further, a predetermined value is obtained by a band pass filter (BPF) 302. Only frequency components (high frequency components) are extracted. The detector (DET) 303 performs detection processing such as peak hold and integration on the imaging signal from which only a predetermined high frequency component is extracted, and outputs an evaluation value FV of the imaging signal AF to the focus control unit 233.

  Further, the high-frequency component is removed from the imaging signal TVS that has passed through the focus detection gate 301 by a low-pass filter (LPF) 304. A line maximum value circuit (Line Max) 305 detects the maximum value of one horizontal line of the imaging signal from which the high frequency component has been removed. A line minimum value circuit (Line Min) 306 detects the minimum value of one horizontal line of the imaging signal from which the high frequency component has been removed.

  The adder 307 calculates a difference (maximum value−minimum value) between the maximum value and the minimum value of one horizontal line.

  A peak hold circuit (Peak Hold) 308 detects the maximum value-minimum peak value MM of all lines in the focus detection gate. This substantially corresponds to the maximum value of contrast in the focus detection gate.

  For each focus detection gate, the divider 309 divides the evaluation value FV by the peak value MM to calculate a focus degree IFA for each focus detection frame. When there are a plurality of focus detection gates 301, there are a plurality of subsequent circuits, and the evaluation value FV / in-focus level IFA is also a plurality of signals. The focus control 233 selects an optimum signal from such a plurality of signals according to conditions, or performs an autofocus operation based on the plurality of signals.

  FIG. 4A is a graph showing the relationship between the evaluation value FV of the imaging signal AF and the imaging conditions, and FIG. 4B is a graph showing the relationship between the in-focus degree IFA and the imaging conditions. Referring to FIG. 4A, the evaluation value FV of the imaging signal AF varies greatly depending on the shooting conditions (subject type, subject brightness, illuminance, focal length, etc.).

  The evaluation value FV (A) shown in FIG. 4A indicates a change in signal when the focus lens 231 is driven from a large blur (out of focus) to a focus when a general subject A is photographed. ing. On the other hand, the evaluation value FV (B) indicates a signal change in the case of the high contrast subject B, and the evaluation value FV (C) indicates a signal change in the case of the low contrast (low illumination) subject C. Yes.

  On the other hand, as shown in FIG. 4B, the in-focus level IFA is almost the same level in any of the subjects A, B, and C as shown in FIG. Therefore, if any of the subjects A, B, and C is determined based on the common threshold value, the degree of blur is the same.

  FIG. 5 is a diagram schematically showing the relationship between the position of the focus lens (position with respect to the focal point) and the focus detection method. FIG. 5A shows a case where the recording mode setting is performed in the imaging / recording setting unit 108 so as to perform recording at a high resolution and a low compression rate such as HD recording. When the in-focus level IFA shown in FIG. 4 exceeds the point CP1 of the threshold value TH1, the focus detection method is switched from the direct focus detection AF to the imaging signal AF. As a result, the direct focus detection AF is smoothly switched to the imaging signal AF at a position (CP1) with the same degree of blurring. Further, by determining (detecting) the focal point by the imaging signal AF, the focal point is reached with high accuracy. In this case, since switching to the imaging signal AF is performed before entering the range of the in-focus position variation Er of the direct focus detection AF, smooth switching is possible.

  On the other hand, FIG. 5B shows a case where the recording mode is set in the imaging recording setting unit 108 so as to perform recording at a low resolution or a high compression rate. FIG. 5B shows an example in which the in-focus accuracy is not so high, and the in-focus point is determined only by direct focus detection AF to reach the in-focus point quickly in order to reach the in-focus point quickly. In this case, it is not known where to stop within the range of in-focus position variation Er for direct focus detection. However, if this range is smaller than the stop position of the focus lens for satisfying the resolution of the captured image, it may be stopped within the range of the focus position variation Er for direct focus detection. Therefore, which of the focus detection method shown in FIG. 5A and the focus detection method shown in FIG. 5B is selected depends on the accuracy of the direct focus detection unit 230. For example, if the accuracy of the direct focus detection unit 230 is increased so that SD recording is sufficiently accurate, the focus detection method shown in FIG. 5B is selected, and the in-focus point is reached only by direct focus AF in SD recording. Is possible. However, since high-precision focusing is required for HD recording, the focusing operation using the focus detection method shown in FIG. 5A is selected.

  Next, processing (operation) of the focus control unit 233 will be described with reference to FIG. FIG. 6 is a flowchart for explaining the operation of the focus control unit 233.

  First, 1 is substituted into AFMODE representing the AF state (step 601). Next, the imaging signal processing by the imaging signal processing circuit 242, the AF signal processing by the AF signal processing circuit 234, and the phase difference detection processing by the phase difference detector 239 are performed synchronously (step 602). Thus, the evaluation value FV signal and the in-focus level IFV signal are acquired from the AF signal processing circuit 234, and the distance signal D is acquired from the phase difference detector 239 (step 603).

  Next, AFMODE is determined (step 604). In the present embodiment, if AFMODE is 1, the process branches to step 605, if AFMODE is 2, the process branches to step 621, and if AFMODE is 3, the process branches to step 631.

  If AFMODE is 1 in step 604, the driving direction and speed of the focus lens 231 are determined based on the distance signal D acquired in step 603 and the current position of the focus lens 231 (step 611). Specifically, in the direction in which the focus lens 231 approaches the position of the distance signal D, the direction and speed are determined so as to be high when the distance is long and low when the distance is close.

  Next, the current recording mode setting state is determined (step 612). When the recording mode is set to high resolution recording, low compression recording, HD recording, or the like, the level of the focus degree IFA acquired in step 603 is compared with the threshold value TH1 (step 613). When the level of the focusing degree IFA is larger than the threshold value TH1, since it is located in the vicinity of the focusing point, 2 is substituted into AFMODE (step 614), and the focus lens 231 is moved at the determined driving speed and direction. Drive (step 641). On the other hand, when the level of the in-focus level IFA is smaller than the threshold value TH1, the process proceeds to step 641 as it is. In step 641 and subsequent steps, step 602 and subsequent steps are repeated in synchronization with the readout cycle (imaging signal processing cycle) of the image sensor 241.

  On the other hand, if the recording mode is set to low resolution recording, high compression recording, SD recording or the like in step 612, the focus state is determined based on the comparison between the distance signal D and the current position of the focus lens 231. Is determined (step 613). If the distance signal D matches the current position of the focus lens 231, it is determined that the focus is in focus, and if it does not match, it is determined that the focus is not in focus. If it is determined in step 613 that the focus state has been achieved, the focus lens 231 is set to stop (that is, the drive speed is set to 0) (step 616), and the process proceeds to step 641. If it is determined in step 613 that the camera is out of focus, the process proceeds to step 641 as it is.

  In step 604, when AFMODE is 2, it is determined whether or not the evaluation value FV of the imaging signal AF acquired in step 603 is increasing (decreasing) (step 621). This determination is an increase / decrease comparison with the previous reading result of the image sensor 241, and although the description is omitted in the present embodiment, it is assumed that the previous evaluation value FV is held.

  If the evaluation value FV has not increased, the drive direction of the focus lens 231 is set in reverse (step 622), and it is determined whether or not it is a decrease after passing the peak of the evaluation value FV (step 623). . If it is a decrease after passing through the peak of the evaluation value FV, 3 is substituted into AFMODE (step 624), and the process proceeds to step 641. If it is not a decrease after passing through the peak of the evaluation value FV (that is, not passing through the peak), the process proceeds to step 641 as it is.

  In step 604, when AFMODE is 3, the focus lens 231 is driven to the peak position (focus position) of the evaluation value FV of the imaging signal AF (step 631). Next, it is determined whether or not the evaluation value FV has changed from the level at the peak position of the evaluation value FV, and whether or not the distance signal D has changed from the in-focus position is determined (step 632). If it has changed, 1 is assigned to AFMODE (step 633), and the process proceeds to step 641 (restart). If not, the process proceeds to step 641 as it is.

  In the present embodiment, the case where the recording mode is set to high resolution recording, low compression recording, HD recording, and the like, and the case where the recording mode is set to low resolution recording, high compression recording, SD recording, etc. have been described. However, it goes without saying that the present invention may be applied when the recording mode is set to still image capturing and when the recording mode is set to moving image capturing.

  FIG. 7 is a graph showing the relationship between the position of the focus lens 231 and the in-focus degree IFA2. The in-focus level IFA2 is a difference between the distance signal D and the current position of the focus lens 231. In the second embodiment, as shown in FIG. 7, focus detection is controlled using the in-focus degree IFA2.

  FIG. 8 is a diagram schematically showing the relationship between the position of the focus lens (position with respect to the focal point) and the focus detection method. When the recording / recording setting unit 108 sets the recording mode so as to perform recording at a high resolution (or a low compression rate) such as HD recording, as shown in FIG. The focal point is detected using the direct focus detection AF until the degree of focus. In the vicinity of the focal point, the focal point is detected using the imaging signal AF. In the second embodiment, a point CP2 at which the in-focus level IFA2 is equal to or less than the threshold value TH2 is set as a predetermined in-focus level.

  On the other hand, when the recording mode is set in the imaging recording setting unit 108 so as to perform recording at a low resolution (or high compression rate), first, as shown in FIG. Direct focus detection AF is used up to the focal point detected at 239. Then, after focusing by direct focus detection AF, focus detection is performed again using the imaging signal AF.

  In the case of FIG. 8A, since the image signal AF is switched outside the range of the focus position variation Er in the direct focus detection AF, the operation is smoothly performed to the focus. On the other hand, in the case of FIG. 8B, it is not known where the position reached by the direct focus detection AF stops within the range of the focus position variation Er of the direct focus detection AF. However, since the imaging recording setting (recording mode) is low resolution (or high compression rate), it does not matter where it stops in this range, and it is important to increase the speed until final focusing. Yes.

  Next, processing (operation) of the focus control unit 233 will be described with reference to FIG. FIG. 9 is a flowchart for explaining the operation of the focus control unit 233. In FIG. 9, steps with the same reference numbers as those in FIG.

  Referring to FIG. 9, through step 601 and step 602, the evaluation value FV signal is obtained from the AF signal processing circuit 234, the distance signal D is obtained from the phase difference detector 239, and the degree of focus IFA2 is calculated (step). 701).

  If AFMODE is 1 in step 604, the current recording mode setting state is determined through step 611 (step 702). When the recording mode setting mode is set to high resolution recording, low compression recording, HD recording, or the like, the level of the focus degree IFA2 calculated in step 701 is compared with the threshold value TH2 (step 703). If the level of the focusing degree IFA2 is larger than the threshold value TH2, the process proceeds to step 641 as it is. When the level of the focusing degree IFA2 is smaller than the threshold value TH2, since it is located in the vicinity of the focusing point, 2 is substituted into AFMODE (step 704), and the process proceeds to step 641.

  On the other hand, if the recording mode setting mode is set to low resolution recording, high compression recording, SD recording or the like in step 702, based on the comparison between the distance signal D and the current position of the focus lens 231, The in-focus state is determined (step 705). If it is determined that it is in focus, the process proceeds to step 704, and if it is determined that it is out of focus, the process proceeds to step 641 as it is.

  A third embodiment will be described with reference to FIGS. 8 and 10. FIG. 10 is a flowchart for explaining the operation of the focus control unit 233. In FIG. 10, steps with the same reference numbers as those in FIGS. 6 and 9 are the same operations, and thus description thereof is omitted.

  Referring to FIG. 10, through step 611, the current recording mode setting state is determined (step 801). In the third embodiment, it is determined whether the recording mode is moving image recording or still image recording. If the recording mode is moving image recording, the process proceeds to step 703. If the recording mode is still image recording, the process proceeds to step 705.

  In moving image recording, since the quality in the focusing process is also important, as shown in FIG. 8A, imaging is performed from the direct focus detection AF at a position CP2 outside the focus position variation Er in the direct focus detection. Switch to signal AF. Thereby, smooth AF without hunting or the like can be realized.

  On the other hand, in the case of still image recording, it may be finally focused. In other words, even if the movement of the focusing process is somewhat unsightly, priority is given to focusing quickly, so as shown in FIG. 8B, it can be seen where in the range of variation Er in direct focus detection stops. The movement may become unsightly. However, in the case of still image recording, priority is given to focusing at high speed.

  In the first to third embodiments, the focus degree IFA is described in the first embodiment and the focus degree IFA2 is used in the second and third embodiments. However, the focus degree IFA2 is set in the first embodiment. The focus degree IFM may be used in the second and third embodiments.

  In this embodiment, as an example of the direct focus detection AF that directly measures the distance, the external measurement phase difference detection is used. However, the present invention is not limited to this. A focal point is detected based on a detection signal different from a signal corresponding to a predetermined frequency component of an imaging signal obtained by photoelectrically converting an image of a subject formed by an imaging optical system by an imaging unit, for example, a TTL phase difference Infrared AF or the like that obtains the distance of the subject from the principle of triangular focus detection by receiving infrared rays that are detected and projected onto the subject may be used.

  The imaging apparatus 200 has a method of detecting (determining) a focal point using an imaging signal AF and a direct focus according to a recording mode (high resolution, low resolution, low compression rate, high compression rate, HD recording, SD recording, etc.). A method of detecting the focal point by detection AF can be selected. Thereby, it is possible to ensure sufficient focusing accuracy for various recording modes and to realize high-speed focus detection.

  Further, the imaging apparatus 200 selects a method of switching from the direct focus detection AF to the imaging signal AF and a method of detecting the focus only by the direct focus detection AF according to the recording mode (and depending on the degree of focus). be able to. Thereby, it is possible to ensure sufficient focusing accuracy for various recording modes and to realize high-speed focus detection.

  Further, the imaging apparatus 200 uses a method of switching from the direct focus detection AF to the imaging signal AF in accordance with the recording mode (and in accordance with the degree of focus) and the imaging signal AF after being focused only by the direct focus detection AF. Further, a method for correcting the focal point can be selected. Thereby, it is possible to ensure sufficient focusing accuracy for various recording modes and to realize high-speed focus detection. Further, in still image recording, focusing can be performed as fast as possible, while in moving image recording, the quality of the focusing process can be maintained, and shooting with smooth AF is possible.

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to these embodiments, and various modifications and changes can be made within the scope of the gist. For example, an AF method may be selectable between a mode in which an image is captured and recorded and a mode in which an image is displayed on a monitor without recording. Thereby, it is possible to ensure sufficient focusing accuracy for various recording modes and to realize high-speed focus detection.

It is a schematic block diagram which shows the structure of the focus detection apparatus as 1 side surface of this invention. It is a schematic block diagram which shows the structure of the imaging device as 1 side surface of this invention. FIG. 3 is a schematic block diagram showing a specific configuration of the AF signal processing circuit shown in FIG. 2. It is a graph which shows the relationship between the evaluation value of an imaging signal, a focus degree, and imaging conditions. It is a figure which shows typically the relationship between the position (position with respect to a focusing point) of a focus lens, and a focus detection system. 3 is a flowchart for explaining the operation of a focus control unit shown in FIG. 2. It is a graph which shows the relationship between the position of a focus lens, and a focus degree. It is a figure which shows typically the relationship between the position (position with respect to a focusing point) of a focus lens, and a focus detection system. 3 is a flowchart for explaining the operation of a focus control unit shown in FIG. 2. 3 is a flowchart for explaining the operation of a focus control unit shown in FIG. 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Focus detection apparatus 101 Direct focus detection unit 102 Imaging signal detection unit 103 Mountain climbing control part 104 Generation | occurrence | production means 105 Selection means 106 Switch 107 Lens drive system 108 Imaging record setting part 200 Imaging apparatus 201 Lens unit 213 Zoom control part 231 Focus lens 233 Focus Control unit 234 AF signal processing circuit 242 Imaging signal processing circuit 251 Main control unit

Claims (13)

First focus detection means for detecting a focal point using an evaluation signal representing a focus state of an imaging optical system based on an imaging signal obtained by photoelectrically converting a subject image by an imaging means;
Second focus detection means for detecting a focal point based on a detection signal different from the evaluation signal;
First control for controlling to detect the in-focus point using at least the second focus detection unit, and detecting the in-focus point using the first focus detection unit and the second focus detection unit. A focus detection apparatus comprising: selection means for selecting a second control different from the first control to be controlled according to a recording mode of an image obtained by the imaging means. First focus detection means for detecting a focal point using an evaluation signal representing a focus state of an imaging optical system based on an imaging signal obtained by photoelectrically converting a subject image by an imaging means;
Second focus detection means for detecting a focal point based on a detection signal different from the evaluation signal;
A focus degree detecting means for detecting the degree of focus of the imaging optical system;
According to the first control for controlling the second focus detection means to detect the in-focus point and the degree of focus detected by the focus degree detection means, from the first focus detection means to the first focus detection means. And a second control for controlling to detect the focal point by switching to the two focus detection means, and a selection means for selecting according to a recording mode of an image obtained by the imaging means. apparatus. First focus detection means for detecting a focal point using an evaluation signal representing a focus state of an imaging optical system based on an imaging signal obtained by photoelectrically converting a subject image by an imaging means;
Second focus detection means for detecting a focal point based on a detection signal different from the evaluation signal;
A focus degree detecting means for detecting the degree of focus of the imaging optical system;
The in-focus point is detected by the second focus detection unit, the imaging optical system is moved to the in-focus point, and then the imaging optical system is driven around the in-focus point by the first focus detection unit. Switching from the second focus detection means to the first focus detection means in accordance with the first control for controlling to detect the focus and the degree of focus detected by the focus degree detection means. A focus detection apparatus comprising: selection means for selecting second control for controlling to detect a focal point according to a recording mode of an image obtained by the imaging means.   The recording mode is a setting value of the resolution of an image obtained by the imaging unit, and the selection unit selects the first control when the recording mode has the first resolution, and the recording 4. The focus detection according to claim 1, wherein the second control is selected when a mode has a second resolution higher than the first resolution. 5. apparatus.   The focus detection apparatus according to claim 4, wherein the second resolution is a high-vision standard.   The recording mode is a set value of a compression rate of an image obtained by the imaging unit, and the selection unit selects the first control when the recording mode has a first compression rate, 4. The method according to claim 1, wherein the second control is selected when the recording mode has a second compression rate lower than the first compression rate. 5. The focus detection apparatus described. The recording mode is a setting of whether the image obtained by the imaging means is a still image or a moving image,
The selection means selects the first control when the recording mode is a still image, and selects the second control when the recording mode is a moving image. The focus detection apparatus according to any one of claims 1 to 3.   8. The method according to claim 2, wherein the focus degree detection unit detects a degree to a focus point of the imaging optical system based on a signal obtained from the imaging signal. The focus detection apparatus described.   The in-focus degree detection unit detects a degree to the in-focus point of the imaging optical system based on a detection result of the first focus detection unit and a lens position of the imaging optical system. The focus detection apparatus according to any one of claims 2 to 7. An imaging device that captures a subject image via an imaging optical system,
A focus detection device according to any one of claims 1 to 9,
An imaging apparatus comprising: drive means for driving a lens constituting the imaging optical system based on a detection result of the focus detection apparatus. First focus detection means for detecting a focal point using an evaluation signal representing a focus state of an imaging optical system based on an imaging signal obtained by photoelectrically converting a subject image by an imaging means, and detection different from the evaluation signal A focus detection method for a focus detection apparatus, comprising: a second focus detection unit configured to detect a focal point based on a signal,
A first detection step of detecting a focal point using at least the second focus detection means;
A second detection step different from the first detection step of detecting a focal point using the first focus detection means and the second focus detection means;
A focus detection method comprising: a selection step of selecting the first detection step or the second detection step according to a recording mode of an image obtained by the imaging unit. First focus detection means for detecting a focal point using an evaluation signal representing a focus state of an imaging optical system based on an imaging signal obtained by photoelectrically converting a subject image by an imaging means, and detection different from the evaluation signal A focus detection method for a focus detection apparatus, comprising: a second focus detection unit configured to detect a focal point based on a signal,
A first detection step of detecting a focal point by the second focus detection means;
The degree of focus of the imaging optical system is detected, and the focus detection by the first focus detection means is detected from the detection of the focus by the second focus detection means according to the detected focus degree. A second detection step of switching to and detecting the focal point;
A focus detection method comprising: a selection step of selecting the first detection step or the second detection step according to a recording mode of an image obtained by the imaging unit. First focus detection means for detecting a focal point using an evaluation signal representing a focus state of an imaging optical system based on an imaging signal obtained by photoelectrically converting a subject image by an imaging means, and detection different from the evaluation signal A focus detection method for a focus detection apparatus, comprising: a second focus detection unit configured to detect a focal point based on a signal,
A second focal point detection unit detects the focal point, moves the imaging optical system to the focal point, and then detects the focal point by the second focal point detection unit in the vicinity of the focal point. 1 detection step;
A focus degree detecting step for detecting the degree of focus of the imaging optical system;
A second detection step of detecting the in-focus by switching from the in-focus detection by the second focus detection means to the detection of the in-focus by the first focus detection means according to the detected degree of focus. When,
A focus detection method comprising: a selection step of selecting the first detection step or the second detection step according to a recording mode of an image obtained by the imaging unit.