JP2010113213A - Imaging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure a sufficient movable range of a focus lens for reducing out-of-focus caused by deflection in the optical axis direction immediately before imaging. <P>SOLUTION: An optical device is the imaging device 1 or an interchangeable lens device 2. The imaging device includes: a focus detecting means 105 for detecting a focal state of an imaging optical system, a light guiding means 104 changing between a first state for guiding light to the focus detecting means and a second state for guiding no light to the focus detecting means, and a first controlling means 3 for controlling the position of the focus lens 21 in a first movable range based on the focus detection result in the first state. The optical device includes: a deflection detecting means 24 for detecting the deflection in the optical axis direction, and a second controlling means 5 for controlling the position of the focus lens in a second movable range based on the focus detection result after switching from the first state to the second state is started. A close end of the second movable range is set on a closer side than a close end of the first movable range. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical apparatus used in an imaging system capable of focus control based on a focus detection result and focus control based on a shake detection result in the optical axis direction.

  An imaging device such as a single-lens reflex digital camera detects the focus state of the imaging optical system using light from the imaging optical system, and moves the focus lens to the in-focus position calculated based on the detection result In many cases, an (AF) function is installed. In a single-lens reflex digital camera, during AF (when the release switch is half-pressed), a focus detection unit that detects light from the imaging optical system via the mirror arranged in the imaging optical path. Lead to. This mirror is retracted out of the imaging optical path during imaging (when the release switch is fully pressed).

  In many cases, an imaging device or an interchangeable lens attached to the imaging device is equipped with a so-called image stabilization function for reducing image blur caused by camera shake or the like. In the conventional general image stabilization function, the image stabilization operation is started in response to the half-press operation of the release switch, and the image stabilization operation is stopped in response to the full-press operation of the release switch.

  However, when the photographer holds the image pickup device in his / her hand and performs macro photography, the photographing magnification is high, and the focus is shifted due to a minute change in distance from the subject (that is, shake in the optical axis direction of the image pickup device). . For this reason, when performing macro photography, it is desirable that the AF operation is performed after the release switch is fully pressed and before the mirror is completely retracted and before the actual imaging is started. However, if the mirror is retracted to the outside of the imaging optical path in response to the full pressing operation of the release switch, light cannot be guided to the focus detection unit. Therefore, AF operation cannot be performed using the focus detection unit after the release switch is fully pressed. .

Patent Document 1 uses a shake sensor that detects a shake (displacement) in the optical axis direction of an imaging optical system, and performs focus control based on an output signal from the shake sensor after the mirror is retracted outside the imaging optical path. A method is disclosed.
Japanese Patent Laid-Open No. 10-312006

  However, the method disclosed in Patent Document 1 has the following problems. This problem will be described with reference to FIG.

  In FIG. 6, C is the position of the focus lens immediately before the release switch is fully pressed, and indicates the position near the closest end of the movable range of the focus lens. This position C is in the vicinity of the near end detection switch.

  The close end detection switch is located slightly infinitely far from the mechanical close end of the focus lens (mechanical close end), and the focus lens moves before the focus lens contacts the mechanical close end. It is provided to perform stop control.

  After the release switch is fully pressed from the state shown in FIG. 6, focus shift occurs due to shake in the optical axis direction before the actual imaging starts, and the focus lens is moved to the position C based on the output signal from the shake sensor. Suppose you need to move from the In this case, a sufficient amount of movement of the focus lens to the close side cannot be obtained due to the presence of the close end detection switch.

  The present invention provides an optical apparatus capable of ensuring a sufficient movable range of a focus lens for reducing a focus shift caused by an optical axis direction shake immediately before imaging.

  An optical apparatus according to one aspect of the present invention is one of an imaging device and an interchangeable lens device. The imaging apparatus uses a light from the imaging optical system to detect a focus state of the imaging optical system, a first state for guiding the light to the focus detection means, and does not guide the light to the focus detection means The light guide means that switches to the second state, and the position of the focus lens included in the imaging optical system based on the detection result of the focus detection means when the light guide means is in the first state within the first movable range. First control means for controlling. The interchangeable lens device includes an imaging optical system. The optical device includes a shake detection unit that detects a shake of the optical device in the optical axis direction of the imaging optical system, and a shake detection unit after the light guide unit starts switching from the first state to the second state. And a second control means for controlling the position of the focus lens in the second movable range based on the detection result of And a 2nd control means sets the near end of a 2nd movable range to the near side compared with the close end of a 1st movable range.

  In the present invention, after the light guide unit starts switching from the first state to the second state and the focus state cannot be detected by the focus detection unit, the focus lens is based on the detection result by the shake detection unit. Control the position of the. At this time, the focus lens can be moved closer than the case where the light guide means is in the first state and the position of the focus lens is controlled based on the focus detection result by the focus detection means. Become. For this reason, according to the present invention, in the case of performing imaging with a large influence of shake (focus shake) in the optical axis direction such as macro photography, even after the light guide unit starts the switching, excellent focus shake correction is performed. A movable range of the focus lens for performing the above can be ensured.

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

  1 and 2 show a single-lens reflex camera main body (imaging apparatus: hereinafter referred to as a camera main body) that is an embodiment of the present invention, and an interchangeable lens (interchangeable lens apparatus) that is detachably attached to the camera main body. The structure of the imaging system comprised by these is shown. In this embodiment, the interchangeable lens corresponds to an optical device.

  Reference numeral 1 denotes a camera body, and 2 denotes an interchangeable lens.

  In FIG. 2, the interchangeable lens 2 includes an imaging optical system including a focus lens 21, a diaphragm 22, a variable power lens 23, and another lens (not shown).

  The camera body 1 is provided with an image sensor 101 composed of photoelectric conversion elements such as a CCD sensor and a CMOS sensor. Reference numeral 102 denotes a shutter that controls the exposure amount of the image sensor 101.

  Reference numeral 103 denotes a main mirror, and as shown by a solid line in the figure, a first state in which the main mirror is arranged obliquely in an optical path of light from the interchangeable lens 2 (imaging optical system) (hereinafter referred to as an imaging optical path); As shown by a two-dot chain line in the figure, the second state is switched (moved) to the second state of retreating from the imaging optical path. In the first state, the main mirror 103 reflects a part of the light from the imaging optical system, guides it to a finder optical system described later, and transmits the remaining light. In the second state, the light from the imaging optical system is directly directed to the shutter 102 and the image sensor 101.

  Reference numeral 104 denotes a sub-mirror, which is in a first state in which the main mirror 103 and the main mirror 103 are disposed obliquely in the imaging optical path, and a second state in which the main mirror 103 is retracted outside the imaging optical path. Switch (move). In the first state, the sub mirror 104 reflects light from the imaging optical system that has passed through the main mirror 103 and guides it to a focus detection unit (focus detection means) 105 described later. In the second state, the light from the imaging optical system is directly directed to the shutter 102 and the image sensor 101. That is, the sub mirror 104 does not guide the light from the imaging optical system to the focus detection unit 105 in the second state. The main mirror 103 and the sub mirror 104 constitute light guiding means.

  The focus detection unit 105 forms a pair of subject images (hereinafter referred to as two images) using the light from the imaging optical system guided by the sub-mirror 104, and detects a shift amount, that is, a phase difference between the two images. The focus state is detected (focus detection) by the phase difference detection method. The phase difference corresponds to the focus state of the imaging optical system. The defocus amount of the imaging optical system can be calculated based on the phase difference by the focus detection unit 105, that is, the detection result of the focus state (hereinafter referred to as the focus detection result).

  Reference numeral 106 denotes a prism that inverts a subject image formed on a focus plate (not shown) by light reflected by the main mirror 103 in the first state, and 107 denotes a photographer (not shown) that emits light from the prism 106. It is an eyepiece that leads to the eyes. These prism 106 and eyepiece lens 107 constitute a finder optical system.

  In FIG. 1, reference numeral 3 denotes a camera CPU (first control means) provided in the camera body 1 and constituted by a microcomputer. The camera CPU 3 controls the operation of each component in the camera body 1 and communicates with a lens CPU (second control means) 5 provided in the interchangeable lens 2 via a communication contact 4. Information transmitted from the camera CPU 3 to the lens CPU 5 includes focus drive amount information, aperture drive amount information, and mirror drive time information, which will be described later. Information received by the camera CPU 3 from the lens CPU 5 includes image magnification information described later.

  Reference numeral 6 denotes a main switch (power switch) that can be operated from the outside. When this switch is turned on, the camera CPU 3 is activated and power supply to each component in the camera body 1 and the interchangeable lens 2 is started. .

  A photometric sensor 9 receives light from the imaging optical system guided through the prism 106 described above, and measures subject luminance. The measured subject luminance is input to the camera CPU 3 as a photometric result (measurement result).

  7 (S1) is an imaging preparation switch that is turned on by a half-press operation (first stroke operation) of a shutter button (not shown), and 8 (S2) is turned on by a full-press operation (second stroke operation) of the shutter button. This is an imaging start switch.

  When the imaging preparation switch 7 is turned on, the camera CPU 3 starts an imaging preparation operation. In the imaging preparation operation, the camera CPU 3 calculates the defocus amount of the imaging optical system based on the focus detection result (phase difference) obtained by the focus detection unit 105. Furthermore, the camera CPU 3 calculates the drive amount (including the drive direction) of the focus lens 21 for obtaining the focus based on the defocus amount. Further, the camera CPU 3 calculates the driving amount of the diaphragm 22 and the shutter speed based on the photometric result obtained by the photometric sensor 9. Information on the driving amount of the focus lens 21 and the driving amount of the aperture 22 is transmitted to the lens CPU 5 as focus driving amount information and aperture driving amount information, respectively.

  On the other hand, the lens CPU 5 causes the focus motor control unit 14 to control the focus motor 15 according to the focus drive amount information, and moves the focus lens 21 to obtain focus. In this way, the position (drive) of the focus lens 21 for obtaining focus is controlled by the camera CPU 3 via the lens CPU 5.

  When the imaging start switch 8 is turned on after such an imaging preparation operation is completed, the camera CPU 3 transmits an aperture drive command to the lens CPU 5. The lens CPU 5 that has received the aperture drive command causes the aperture controller 13 to drive the aperture 22 in accordance with the aperture drive amount information.

  Further, the camera CPU 3 causes the mirror / shutter control unit 18 to retract the mirror unit constituted by the main mirror 103 and the sub mirror 104 out of the imaging optical path, and then operates the shutter 102 at the previously calculated shutter speed. Thereby, an imaging operation (exposure of the image sensor 101) is started.

  Reference numeral 24 shown in FIGS. 1 and 2 denotes a shake sensor as shake detection means, which is provided on the interchangeable lens 2. The shake sensor 24 detects the shake of the interchangeable lens 2 (and the camera body 1) in the optical axis direction of the imaging optical system. The shake sensor 24 includes an acceleration sensor and other sensors capable of detecting shake in the optical axis direction, and outputs a detection signal (a shake detection result) corresponding to the shake.

  The lens CPU 5 starts the driving of the diaphragm 22 and the retracting operation of the mirror unit (switching from the first state to the second state) and then before the operation of the shutter 102, that is, the exposure of the image sensor 101 is started. Before performing imaging (hereinafter referred to as imaging), AF using the shake detection result is performed.

  Here, the lens CPU 5 sets an imaging preparation focus movable range and a focus movable range before imaging (exposure).

  The imaging preparation focus movable range (first movable range) is a movable range of the focus lens 21 during AF using the focus drive amount information in the imaging preparation operation. The focus movable range before imaging (second movable range) is a movable range of the focus lens 21 during AF using the shake detection result in “before imaging” described above.

  In other words, the imaging preparation focus movable range is a movable range of the focus lens 21 in which the position of the focus lens 21 is controlled in AF when the mirror unit is in the first state. Further, the focus movable range before imaging is a movable range of the focus lens 21 in which the position of the focus lens 21 is controlled in AF after the mirror unit starts switching from the first state to the second state.

  In this embodiment, the infinite end of the pre-imaging focus movable range is the same position as the infinite end of the pre-imaging focus movable range, but the closest end of the pre-imaging focus movable range is the maximum of the imaging preparatory focus movable range. It is set closer to the near end than the near end. This will be described in detail later.

  The lens CPU 5 sets the focus movable range before imaging based on at least one of the aperture driving amount information and the mirror driving time information. From the aperture drive amount information, until the drive of the aperture is completed after the drive from the open state of the aperture 22 is started, that is, until the aperture of the aperture 22 calculated by the camera CPU 3 is operated according to the photometric result. It is possible to obtain the time required for aperture (aperture driving time).

  Further, the mirror driving time information is the time required from when the mirror unit starts the retracting operation from the first state to the second state until the retracting operation is completed, that is, from the first state to the second state. The time required for switching to (mirror drive time) is shown.

  In this embodiment, the pre-imaging focus movable range is set according to both the aperture drive amount information and the mirror drive time information, but it is also possible to set the pre-image focus movable range according to only one of them. is there. Further, the driving of the diaphragm 22 and the switching of the mirror unit described above are started according to the operation of the imaging start switch 8. For this reason, the pre-imaging focus movable range may be set according to the time required from the time when the imaging start switch 8 is operated until the driving of the diaphragm 22 and the switching of the mirror unit are completed.

  In FIG. 1, reference numeral 16 denotes a focus lens position encoder as position detection means for detecting the position of the focus lens 21. An output signal from the focus lens position encoder 16 is input to the lens CPU 5. Based on the output signal, the lens CPU 5 detects the position of the focus lens 21 and calculates the shooting magnification of the imaging optical system. The photographing magnification information, which is information indicating the photographing magnification, is also transmitted to the camera CPU 3 as described above. The photographing magnification indicates the magnification of the size on the imaging surface with respect to the actual size of the subject.

  When the lens CPU 5 determines that the photographing magnification is larger than a predetermined magnification, for example, 1.0 times (equal magnification) (that is, macro photographing), the lens CPU 5 shakes in the optical axis direction based on the output signal of the shake sensor 24. Calculate the quantity. Further, the lens CPU 5 calculates the amount of change in the imaging position of the subject image by the imaging optical system, that is, the amount of focus shake (defocus amount: including the direction in which the focus shake occurs) that occurs according to the amount of shake. To do. Then, when the focus shake amount is larger than the predetermined amount, that is, the defocus allowable amount, the lens CPU 5 calculates the drive amount of the focus lens 21 for obtaining the focus based on the focus shake amount. The focus lens 21 is driven based on the driving amount.

  As described above, the lens CPU 5 controls the position (drive) of the focus lens 21 for obtaining focus based on the focus shake amount. The drive amount of the focus lens 21 obtained based on the focus shake amount is hereinafter referred to as a focus shake correction amount.

  Next, operations (processing) performed by the camera CPU 3 and the lens CPU 5 will be described using the flowchart of FIG. This operation is executed in accordance with a computer program stored in the camera CPU 3 and the lens CPU 5 or in a memory provided separately from these.

  When the main switch 6 of the camera body 1 is turned on, power is supplied to the camera CPU 3 and the lens CPU 5 from a battery (not shown) attached to the camera body 1. Then, communication between the camera CPU 3 and the lens CPU 5 is started (step <shown as S> 101).

  Next, the lens CPU 5 drives the diaphragm 11 to the open state (step 102).

  Next, the camera CPU 3 transmits mirror drive time information to the lens CPU 5 (step 103).

  Further, the camera CPU 3 determines whether or not the imaging preparation switch 7 (S1) has been turned ON (step 104). When the imaging preparation switch 7 is turned on, the photometry sensor 9 and the focus detection unit 105 are driven, and the above-described imaging preparation operation is started (step 105).

  That is, the camera CPU 3 calculates the aperture driving amount and the shutter speed based on the photometric result obtained by the photometric sensor 9. The camera CPU 3 calculates the driving amount of the focus lens 21 based on the focus detection result (phase difference) by the focus detection unit 105 and drives the focus lens 21 via the lens CPU 5. Thus, AF when the mirror unit is in the first state is performed within the imaging preparation focus movable range set in advance in the lens CPU 5.

  On the other hand, the lens CPU 5 calculates a subject distance based on the position of the focus lens 21 detected by the focus position encoder 16, and obtains a photographing magnification from the subject distance (step 106). The camera CPU 3 transmits the aperture driving amount information calculated in step 105 to the lens CPU 5.

  Next, the lens CPU 5 sets a pre-photographing focus movable range based on the mirror drive time information and the aperture drive amount information obtained in steps 103 and 106 (step 107).

  Next, the camera CPU 3 determines whether or not the imaging start switch 8 (S2) has been turned ON (step 108). If the imaging preparation switch 7 is turned on, the process proceeds to step 109.

  In step 109, the camera CPU 3 transmits an aperture drive command to the lens CPU 5 and starts the mirror unit up operation (switching from the first state to the second state). The lens CPU 5 that has received the aperture drive command drives the aperture 22 according to the aperture drive amount information. At this time, the lens CPU 5 starts counting time with a built-in timer.

  Next, the lens CPU 5 determines whether or not the photographing magnification obtained in step 106 is larger than a predetermined magnification (whether or not macro photographing is performed) (step 110). If the photographing magnification is larger than the predetermined magnification, the process proceeds to step 111. Otherwise, the process proceeds to step 112.

  In step 111, the lens CPU 5 calculates a focus shake amount (including a focus shake direction) based on an output signal from the shake sensor 24, and further, a focus shake correction amount (a focus shake correction direction) based on the focus shake amount. Calculated). Then, the focus lens 21 is driven according to the focus shake correction amount. That is, focus shake correction is performed. Next, the process proceeds to step 112.

  In step 112, the lens CPU 5 determines whether or not the count value by the timer started in step 109 has reached the longer of the aperture driving time and the mirror driving time. In other words, it is determined whether the driving of the diaphragm 22 and the mirror unit up operation started in Step 109 are completed. If completed, the process proceeds to step 113. If not completed yet, the process returns to step 111 to repeat the focus shake correction.

  In step 113, the camera CPU 3 starts the operation of the shutter 102 at the shutter speed calculated in step 105. Thereby, exposure of the image sensor 101 is started. When the exposure is completed, the process returns to step 102.

  4 and 5 show the imaging preparation focus movable range and the pre-imaging focus movable range, respectively. In these drawings, the horizontal axis indicates the position of the focus lens 21, the left side is the infinity side, and the right side is the closest side.

  The original movable range of the focus lens 21 is an area inside the mechanical stoppers 201 and 202 that mechanically limit the further movement of the focus lens 21 as shown in both drawings. However, it is not preferable that the focus lens 21 abuts (or collides) with the mechanical stoppers 201 and 202. For this reason, end detection switches 203 and 204 are provided inside the mechanical stoppers 201 and 202 and in the vicinity thereof. The end detection switches 203 and 204 output an end detection signal to the lens CPU 5 when the focus lens 21 reaches the position where the switches are provided. The lens CPU 5 stops driving the focus lens 21 in response to the input of the end detection signal.

  The infinite end of the imaging preparation focus movable range indicated by 206 in FIG. 4 is set to a position corresponding to the end detection switch 203. On the other hand, the closest end of the imaging preparation focus movable range 206 is set to a position A that is inside (infinite side) by the range 205 further than the position corresponding to the end detection switch 204. The position A can be detected using the focus position encoder 16.

  On the other hand, the infinite end of the pre-imaging focus movable range indicated by 207 in FIG. 5 is set to a position corresponding to the end detection switch 203, that is, the same position as the infinite end of the imaging preparation focus movable range. However, the closest end of the pre-imaging focus movable range 207 is set to a position corresponding to the end detection switch 204. That is, the close end of the pre-imaging focus movable range 207 is set closer to the close side by the range 205 in FIG. 4 than the close end of the imaging preparation focus movable range 206. In other words, the pre-imaging focus movable range 207 is widened to the near side by the range 205 compared to the imaging preparation focus movable range 206.

  A portion corresponding to the range 205 in the focus movable range 207 before imaging is a drive margin of the focus lens 21 for obtaining (maintaining) focusing on a subject at a closer distance in macro shooting. In FIG. 5, when the focus position of the focus lens 21 by AF in the imaging preparation operation is the position B close to the closest end of the imaging preparation focus movable range 206, the “before imaging” focus shake is set to the imaging preparation focus. There are situations in which correction cannot be completed until the closest end of the movable range 206. Even in this case, it is possible to secure the movable range of the focus lens 21 for performing good focus shake correction by setting the near end of the focus movable range 207 before imaging closer to the near side by the range 205. it can.

  The embodiments described above are merely representative examples, and various modifications and changes can be made to the above-described embodiments when implementing the present invention.

  For example, in the above-described embodiment, a case has been described in which only the closest end of the pre-imaging focus movable range is set closer to the near end than the close proximity end of the imaging preparation focus movable range. However, the infinite end of the pre-imaging focus movable range may be set closer to the closer side than the infinite end of the imaging preparation focus movable range. That is, the pre-imaging focus movable range may be the same as the imaging preparation focus movable range, or may be narrower than the imaging preparation focus movable range.

  In the above-described embodiment, the case of performing “before photographing” focus shake correction when the shooting magnification is larger than the predetermined magnification has been described. However, when the subject distance is shorter than the predetermined distance, the focus shake correction is performed. May be. Further, the focus shake correction may be performed regardless of the shooting magnification and the subject distance.

  In the above embodiment, the case where the interchangeable lens 2 is provided with the shake sensor 24 as the shake detection means and the lens CPU 5 as the second control means for controlling the focus shake correction has been described. However, the shake detection unit and the second control unit may be provided in the camera body. In this case, the camera body corresponds to the optical device.

  Furthermore, in the above-described embodiment, the camera body 1 having the mirror unit as the light guiding means that switches between the first state and the second state by moving back and forth with respect to the imaging optical path has been described. However, the present invention is applied even when using an imaging device that is a means other than the mirror unit and has light guiding means that switches between the first state and the second state without moving back and forth with respect to the imaging optical path. Can do.

1 is a block diagram showing an electrical configuration of an imaging system including a single-lens reflex camera main body and an interchangeable lens according to an embodiment of the present invention. Schematic which shows the mechanical structure of the imaging system shown in FIG. 2 is a flowchart showing the operation of the imaging system shown in FIG. The figure which shows the imaging | photography preparation focus movable range in the imaging system shown in FIG. The figure which shows the focus movable range before imaging | photography in the imaging system shown in FIG. The figure which shows the focus movable range in the conventional imaging system.

Explanation of symbols

1 Camera body 2 Interchangeable lens 3 Camera CPU
5 Lens CPU
6 Main switch 7 Imaging preparation switch 8 Imaging start switch 9 Photometric sensor 101 Image sensor 102 Shutter 103 Main mirror 104 Sub mirror 105 Focus detection unit 21 Focus lens 22 Aperture 23 Variable magnification lens 206 Imaging preparation focus movable range 207 Focus movable range before imaging

Claims (5)

Focus detection means for detecting a focus state of the imaging optical system using light from the imaging optical system, a first state for guiding the light to the focus detection means, and a second state for not guiding the light to the focus detection means And a first movable position of a focus lens included in the imaging optical system based on a detection result of the focus detection unit when the light guide unit is in the first state. An optical apparatus that is one of interchangeable lens apparatuses that includes an imaging apparatus having a first control unit that controls a range, and the imaging optical system, and is detachably attached to the imaging apparatus,
Shake detection means for detecting shake of the optical device in the optical axis direction of the imaging optical system;
A second control unit configured to control a position of the focus lens within a second movable range based on a detection result of the shake detection unit after the light guide unit starts switching from the first state to the second state; Control means,
The optical apparatus according to claim 2, wherein the second control unit sets the closest end of the second movable range closer to the close end of the first movable range.   2. The optical apparatus according to claim 1, wherein the second control unit expands the second movable range closer to the first movable range than the first movable range.   The second control means sets the second movable range based on a time required for the light guide means to switch from the first state to the second state. The optical apparatus according to 1 or 2.   The second control means determines the second movable range based on the time required for the diaphragm of the interchangeable lens device to operate from the open state to the open state calculated based on the measurement result of the subject brightness. The optical apparatus according to claim 1, wherein the optical apparatus is set.   The second control means sets the closest end of the second movable range to the closest end of the first movable range when the photographing magnification is larger than the predetermined magnification or when the subject distance is shorter than the predetermined distance. 5. The optical apparatus according to claim 1, wherein the optical apparatus is set closer to the near side.