JP2008102452A - Imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform optimum focus control in accordance with an optical path split state in an imaging apparatus which performs operation to shift from a plurality of optical path split states to a photographing state. <P>SOLUTION: The imaging apparatus has: an imaging device 106 photoelectrically converting an object image; a finder optical system; a focus detection unit 121 detecting a focus state by using luminous flux from an object; optical path switching units 111 and 122 used to switch the optical path of the luminous flux from the object; and a switching mechanism switching the optical path switching units to a first condition that they guide the luminous flux from the object to the finder optical system and the focus detection unit, a second condition that they guide the luminous flux from the object to the imaging device and the focus detection unit and a third condition that they are positioned outside the optical path of the luminous flux from the object to the imaging device. Then, the apparatus has an integrating and storing means which integrates and stores at least the number of shifting times to the respective first and second conditions. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention provides a first state in which the light beam from the subject is guided to the finder optical system and the focus detection unit, a second state in which the light beam is guided to the image sensor and the focus detection unit, and a third state in which the light beam is retracted out of the optical path. The present invention relates to an imaging apparatus including an optical path switching unit that can be switched between the two states.

  An imaging apparatus provided with the above optical path switching unit (or optical path splitting unit) is disclosed in Patent Document 1. This imaging apparatus is a single-lens reflex digital camera capable of observing a subject using an optical finder (Optical View Finder: OVF) using a light beam from an imaging lens and observing a subject using an electronic finder (Electronic View Finder: EVF).

  In this imaging apparatus, even when subject observation is performed using either an optical finder or an electronic finder (first state and second state), the light path from the imaging lens is detected by the optical path switching unit. To a focus detection unit that performs focus detection. Thereby, high-speed focusing can be performed. Also, when shooting a high-definition still image, the optical path switching unit is retracted outside the imaging optical path in order to avoid a reduction in the amount of light due to the light from the subject passing through the optical path switching unit and the focus shift of the subject image. (Third state). For example, a mirror is used for the optical path switching unit.

Also, Japanese Patent Laid-Open No. 2004-228561 discloses a technique for storing the number of integrated operation of movable parts such as a mirror in a single-lens reflex camera, and correcting the focus detection result according to the number. When the number of mirror operations increases, the mirror stop position accuracy deteriorates due to deformation or wear of the mechanism related to the mirror operation, and a focus detection error occurs. Therefore, a correction amount stored in advance is read according to the number of times the mirror is operated, the number of times of release, and the like, and the focus detection result is corrected using the correction amount.
JP 2004-264832 A (paragraph numbers 0042 to 0046, FIGS. 1, 3, 5 and the like) JP-A-9-54243 (paragraph numbers 0021 to 0026, FIG. 3)

  However, when shifting from a plurality of optical path division states (first and second states) to an imaging state (third state) as in the imaging device of Patent Document 1, between which optical path division state and imaging state Depending on whether or not the transfer operation has been performed, the operating parts and locations where deformation and wear occur differ. In addition, the number of transitions from one optical path split state to the shooting state may be significantly different from the number of transitions from the other optical path split state to the shooting state. Will occur. Further, the influence of the degree of deformation and wear on the focus detection result also differs depending on the optical path division state.

  For this reason, in the image pickup apparatus of Patent Document 1 that can shift from a plurality of optical path division states to a photographing state only by correction based on the number of simple mirror operations as disclosed in Patent Document 2 or the number of operations equivalent thereto, The focus detection result cannot be corrected. That is, the accuracy of focus control decreases.

  Further, in Patent Document 2, since the focus detection result is uniformly corrected according to the number of actuations, it is not possible to perform appropriate correction corresponding to individual differences due to various factors such as component manufacturing errors and assembly errors.

  An object of the present invention is to make it possible to perform optimum focus control or the like in accordance with an optical path division state in an imaging apparatus that performs an operation of shifting from a plurality of optical path division states to a photographing state.

  An imaging apparatus according to one aspect of the present invention includes an imaging element that photoelectrically converts a subject image, a finder optical system that enables observation of the subject image, and a focus detection unit that detects a focus state using a light beam from the subject. , An optical path switching unit used for switching an optical path of a light beam from a subject, and a first state in which the light path from the subject is guided to a finder optical system and a focus detection unit. And a mechanism for switching to a second state leading to the focus detection unit and a third state located outside the optical path of the light flux from the subject to the image sensor. And this invention has an accumulation | storage memory | storage means to accumulate | store and memorize | store the frequency | count of a transition to each of a 1st and 2nd state at least.

  According to the present invention, the number of transitions to each state (optical path division state) can be accumulated and stored for each state. For this reason, it becomes possible to control the imaging device according to the number of times of each of these integration transitions. For example, it is possible to perform optimum focus control according to the degree of deformation and wear of parts for each optical path division state.

  1 to 7 show the configuration of a camera system as an imaging system that is Embodiment 1 of the present invention.

  First, FIG. 6 shows a schematic configuration of the camera system of the present embodiment. The camera system of this embodiment is a single-plate digital color camera using an image sensor such as a CCD sensor or a CMOS sensor. A moving image or a still image can be acquired by driving the image sensor continuously or once. The imaging element is a so-called area sensor, converts received light into an electrical signal for each pixel arranged in a two-dimensional direction, and accumulates electric charges according to the amount of received light.

  In FIG. 6, reference numeral 101 denotes a camera body as an image pickup apparatus, and members described below are arranged therein.

  Reference numeral 102 denotes an interchangeable lens as a lens device, and an imaging optical system 103 as a photographing optical system is disposed therein. The interchangeable lens 102 is detachable from the camera body 101 and is electrically and mechanically connected to the camera body 101 via a mount mechanism.

  A plurality of interchangeable lenses having different focal lengths can be attached to and detached from the camera body 101, and images with various angles of view can be acquired by exchanging the interchangeable lenses.

  The interchangeable lens 102 has a drive mechanism (not shown). This drive mechanism moves the focusing lens that forms part of the imaging optical system 103 in the direction of the optical axis L1 to perform focus adjustment. Note that the focusing lens can also be adjusted by changing the refractive power by changing the interface shape by configuring the focusing lens with a flexible transparent elastic member or a liquid lens.

  In the interchangeable lens 102, a diaphragm (not shown) that adjusts the amount of light of the photographing light flux by changing the opening area of the light passage opening and a drive mechanism (not shown) that drives the diaphragm are arranged. .

  Reference numeral 106 denotes an imaging device housed in the imaging package 124. An optical low-pass that limits the cutoff frequency of the imaging optical system 103 so that a spatial frequency component higher than necessary in the subject image is not transmitted on the imaging element 106 in the optical path from the imaging optical system 103 to the imaging element 106. A filter 156 is provided. The imaging optical system 103 is also provided with an infrared cut filter (not shown).

  A subject image captured by the image sensor 106 is displayed on a display unit (image display unit) 107. The display unit 107 is attached to the back surface of the camera body 101 so that the user can directly observe the image displayed on the display unit 107. Here, if the display unit 107 is composed of an organic EL spatial modulation element, a liquid crystal spatial modulation element, a spatial modulation element using fine particle electrophoresis, etc., the power consumption can be reduced and made thin.

  In this embodiment, a CMOS process compatible sensor (CMOS sensor), which is one of amplification type solid-state image sensors, is used as the image sensor 106 in particular. One of the features of the CMOS sensor is that the MOS transistor of the area sensor unit and peripheral circuits such as an image sensor driving circuit, an AD conversion circuit, and an image processing circuit can be formed in the same process. As a result, the number of masks and process steps can be greatly reduced as compared with the CCD sensor. In addition, it has a feature that random access to an arbitrary pixel is possible, and readout that is thinned for display is easy, and real-time display can be performed at a high display rate.

    The image sensor 106 performs an output operation of a display image and an output operation of a high-definition image by using the above feature.

  Reference numeral 111 denotes a half mirror as a first optical member. The half mirror 111 reflects a part of the light beam from the imaging optical system 103 and guides it to an optical finder described later, and transmits the other light beam. Thereby, the light beam from the imaging optical system 103 is divided.

  The half mirror 111 is a movable mirror that is positioned obliquely in the photographic optical path (on the optical axis L1) or withdraws from the photographic optical path.

  Reference numeral 105 denotes a focusing screen arranged on the planned image formation plane of the subject image. The pentaprism 112 reflects the light beam from the half mirror 111 a plurality of times, converts the inverted image into an erect image, and guides it to the eyepiece lens 109.

  The eyepiece 109 is a lens for observing a subject image formed on the focusing screen 105, and actually has three lenses (109-1, 109-2, 109-3 in FIG. 1) as will be described later. It consists of The focusing screen 105, the pentaprism 112, and the eyepiece lens 109 constitute an optical viewfinder.

  The half mirror 111 has a refractive index of about 1.5 and a thickness of about 0.5 mm. A sub-mirror 122 as a movable second optical member is disposed behind the half mirror 111 (on the image sensor 106 side). Of the light flux that has passed through the half mirror 111, the light flux on or near the optical axis L <b> 1 is reflected toward the focus detection unit 121.

  The sub mirror 122 is rotatable around a rotation shaft 125 described later. The sub mirror 122 is housed in a lower portion of a mirror box (not shown) that holds the half mirror 111 and the sub mirror 122 in a second optical path state and a third optical path state to be described later.

  Reference numeral 104 denotes a pop-up illumination unit that irradiates a subject with illumination light. The pop-up illumination unit projects upward from the camera body 101 when used, and is stored in the camera body 101 when not used.

  Reference numeral 113 denotes a focal plane shutter (hereinafter referred to as a shutter), which has a front curtain and a rear curtain each composed of a plurality of light shielding blades. In the shutter 113, the photographing light flux is shielded by covering the aperture with the front curtain or the rear curtain except when acquiring an image. Further, at the time of image acquisition, the front curtain and the rear curtain travel while forming a slit, thereby causing the photographing light flux to reach the image sensor 106.

  Reference numeral 119 denotes a main switch (power switch) for starting the camera. Reference numeral 120 denotes a release button that can be pressed in two stages. When the release button 120 is half-pressed, a shooting preparation operation (focus adjustment operation, photometry operation, etc.) of the camera is started, and when the release button 120 is fully pressed, the shooting operation is started.

  The focus detection unit 121 detects the focus state of the imaging optical system 103 by a phase difference detection method.

  Reference numeral 123 denotes a finder mode changeover switch. By operating the switch 123, an optical finder mode (OVF mode) and an electronic finder mode (EVF mode) described later can be selectively set. In the OVF mode, the subject image can be observed through the optical viewfinder. In the EVF mode, the subject image can be observed through the display unit 107.

  Reference numeral 180 denotes an information display unit in the optical viewfinder, which displays predetermined information (for example, information on photographing conditions such as shutter speed and aperture value) on the focusing screen 105. The photographer can observe predetermined information together with the subject image by looking into the eyepiece lens 109.

  In the configuration described above, the optical path switching unit including the half mirror 111 and the sub mirror 122 can take the first, second, and third optical path states.

  The first optical path state is a state in which the light beam from the imaging optical system 103 is guided to the optical finder and the focus detection unit 121. The second optical path state is a state in which the light beam from the imaging optical system 103 is guided to the image sensor 106 and the focus detection unit 121. The third optical path state is a state for causing the image sensor 106 to directly receive the light beam from the imaging optical system 103.

  In the first optical path state, the half mirror 111 and the sub mirror 122 are arranged obliquely on the photographing optical path. A part of the light beam from the imaging optical system 103 is reflected by the half mirror 111 to be guided to the optical finder, and the light beam transmitted through the half mirror 111 is reflected by the sub mirror 122 and guided to the focus detection unit 121. As a result, in the first optical path state, the subject image can be observed through the eyepiece lens 109 and the focus detection unit 121 can perform focus detection. The finder mode corresponding to this optical path state is the OVF mode.

  In the second optical path state, the half mirror 111 is disposed obliquely on the photographing optical path. A part of the light beam from the imaging optical system 103 is reflected by the half mirror 111 and guided to the focus detection unit 121, and the light beam transmitted through the half mirror 111 is directed toward the image sensor 106. Note that the sub mirror 122 is in a state of being retracted from the photographing optical path. When the shutter 113 is opened in this second optical path state, a so-called through image generated based on the output of the image sensor 106 can be displayed on the display unit 107. The focus detection unit 121 can also perform focus detection. The viewfinder mode corresponding to this optical path state is the EVF mode. In this optical path state, it is also possible to perform imaging (continuous imaging or moving image imaging), which is a recording image acquisition operation.

  In the third optical path state, the half mirror 111 and the sub mirror 122 are retracted from the photographing optical path. In this optical path state, the light flux from the imaging optical system 103 reaches the image sensor 106 directly by opening the shutter 113. Thereby, imaging can be performed based on the output of the imaging element 106. This imaging in the optical path state can acquire a high-definition still image, and therefore is suitable for performing a large print by enlarging the still image.

  In order to switch the first to third optical path states described above at high speed, the large half mirror 111 is made of a transparent resin as compared with the sub mirror 122, and the weight is reduced. In addition, a polymer thin film having birefringence is attached to the back surface of the half mirror 111. For this reason, when the image is monitored by the display unit 107 in the second optical path state or when high-speed continuous shooting is performed, a stronger low-pass effect corresponding to not imaging using all the pixels of the image sensor 106. Is granted.

  Note that a fine pyramid-shaped periodic structure having a pitch smaller than the wavelength of visible light can be formed on the surface of the half mirror 111 with a resin so as to act as a so-called photonic crystal. Thereby, it is possible to reduce the surface reflection of light due to the difference in refractive index between air and resin, and to increase the light utilization efficiency. With this configuration, it is possible to prevent a ghost from occurring due to multiple reflection of light on the front and back surfaces of the half mirror 111 in the second optical path state.

  The mirror drive mechanism (see 145 in FIG. 7) composed of an electromagnetic motor and a gear train changes the position of the half mirror 111 and the sub mirror 122 to move the optical path switching unit (optical path splitting unit) from the first optical path state to the first optical path state. Switch between 3 optical path states.

  In imaging in the second optical path state, as described later, the half mirror 111 and the sub mirror 122 remain held at predetermined positions, and it is not necessary to operate the mirror drive mechanism. For this reason, it is possible to perform ultra-high-speed continuous shooting by increasing the speed of image processing on the signal from the image sensor 106. Further, the focus adjustment can be performed even when an image is displayed on the display unit 107.

  FIG. 7 shows an electrical configuration of the camera system of the present embodiment. This camera system has an imaging system, an image processing system, a recording / reproducing system, and a control system. First, a description will be given regarding capturing and recording of a subject image. In the figure, the same members as those described in FIG.

  The imaging system includes an imaging optical system 103 and an imaging element 106, and the image processing system includes an A / D converter 130, an RGB image processing circuit 131, and a YC processing circuit 132. The recording / reproducing system includes a recording processing circuit 133 and a reproducing processing circuit 134, and the control system includes a camera system control circuit 135, an operation detection circuit 136, and an image sensor driving circuit 137.

  Reference numeral 138 denotes a standardized connection terminal for connecting to an external computer or the like to transmit and receive data. The above electric circuit is driven by a small fuel cell (not shown).

  The imaging system is an optical processing system that forms an image of a light beam from a subject on the imaging surface of the imaging element 106 via the imaging optical system 103. The imaging system adjusts the diaphragm (light quantity adjustment unit) (not shown) in the interchangeable lens 102 and the travel of the front curtain and rear curtain in the shutter 113 to expose the imaging element 106 with an appropriate light quantity.

  The image sensor 106 has 3700 square pixels arranged in the long side direction and 2800 in the short side direction, and has a total of about 10 million pixels. Each pixel is provided with one of R (red), G (green), and B (blue) color filters, so that two G and four R and B pixels each form one set. It is a Bayer array pixel.

  In the Bayer array, the overall image performance is improved by arranging more G pixels that are easily felt when the photographer looks at the image than the R and B pixels. In general, in image processing using this type of image sensor 106, a luminance signal is generated mainly from G, and a color signal is generated from R, G, and B.

  The signal read from the image sensor 106 is supplied to the image processing system via the A / D converter 130. The A / D converter 130 is a signal conversion circuit that converts a signal from each pixel into, for example, a 10-bit digital signal according to the amplitude thereof, and outputs the signal. Subsequent image signal processing is executed by digital processing. The

  The image processing system is a signal processing system that generates an image signal of a desired format from R, G, and B digital signals. The R, G, and B color signals are converted into a luminance signal Y, a color difference signal (R−Y), It is converted into a YC signal represented by (BY).

  The RGB image processing circuit 131 is a signal processing circuit that processes a signal from 3700 × 2800 pixels received from the image sensor 106 via the A / D converter 130, and is a high-performance white balance circuit, gamma correction circuit, and interpolation calculation. It has an interpolation operation circuit that performs resolution.

  The YC processing circuit 132 is a signal processing circuit that generates a luminance signal Y and color difference signals RY and BY. The processing circuit 132 includes a high-frequency luminance signal generation circuit that generates a high-frequency luminance signal YH, a low-frequency luminance signal generation circuit that generates a low-frequency luminance signal YL, and a color difference that generates color difference signals RY and BY. It consists of a signal generation circuit. The luminance signal Y is formed by combining the high frequency luminance signal YH and the low frequency luminance signal YL.

  The recording / reproducing system is a processing system that outputs an image signal to a recording medium (not shown) (such as a semiconductor memory or an optical disk) and outputs an image signal to the display unit 107. The recording processing circuit 133 performs image signal writing processing and reading processing on the recording medium. The reproduction processing circuit 134 reproduces the image signal read from the recording medium and outputs it to the display unit 107.

  The recording processing circuit 133 also includes a compression / decompression circuit that compresses YC signals representing still images and moving images in a predetermined compression format (for example, JPEG format) and decompresses the compressed data when the compressed data is read out. Have. The compression / decompression circuit includes a frame memory for signal processing. The YC signal from the image processing system is stored in this frame memory for each frame, and is read and compressed for each of a plurality of blocks. The compression encoding is performed, for example, by subjecting the image signal for each block to two-dimensional orthogonal transform, normalization, and Huffman encoding.

  The reproduction processing circuit 134 is a circuit that performs matrix conversion of the luminance signal Y and the color difference signals RY and BY, for example, into RGB signals. The signal converted by the reproduction processing circuit 134 is output to the display unit 107, and a visible image is displayed (reproduced).

  The reproduction processing circuit 134 and the display unit 107 can be connected via a wireless communication line such as Bluetooth. If comprised in this way, the image imaged with the camera can be monitored from the distant place.

  On the other hand, the operation detection circuit 136 which is a part of the control system detects operations of the release button 120, the finder mode changeover switch 123, and the like. The camera system control circuit 135 controls driving of each member in the camera including the half mirror 111 and the sub mirror 122 according to the detection signal of the operation detection circuit 136, and generates and outputs a timing signal at the time of imaging. To do.

  The image sensor drive circuit 137 generates a drive signal for driving the image sensor 106 under the control of the camera system control circuit 135. The information display circuit 142 controls driving of the information display unit 180 in the optical viewfinder.

  The control system controls driving of each circuit in the imaging system, the image processing system, and the recording / reproducing system in accordance with an external operation. For example, the control system detects that the release button 120 has been pressed, and controls the driving of the image sensor 106, the operation of the RGB image processing circuit 131, the compression processing of the recording processing circuit 133, and the like. Further, the control system controls the state of each segment in the information displayed in the optical viewfinder by the in-finder information display circuit 142.

  Next, focus adjustment will be described. An AF control circuit 140 and a lens system control circuit 141 are connected to the camera system control circuit 135. These control circuits communicate with each other data necessary for each process with the camera system control circuit 135 as a center.

  The AF control circuit 140 is included in the focus detection unit 121 (see FIG. 6) and is provided with a focus detection light receiving element (hereinafter referred to as focus detection) provided corresponding to a focus detection area provided at a predetermined position on the photographing screen. A focus detection signal is generated in response to an output signal from 167 (referred to as a sensor). Then, the focus state (defocus amount) of the imaging optical system 103 is detected.

  The AF correction amount storage unit 150 stores in advance correction amount data corresponding to a change with time in the focus detection result associated with the use of the camera (the number of integrated operation of operation parts described later). The data stored in the AF correction amount storage unit 150 may be a calculation formula for calculating the correction amount. The first counter 151 and the second counter 152 count the number of integrated operations of the components constituting the optical path switching unit and the mechanism for driving the optical path switching unit. Details will be described later.

  When the defocus amount is detected, the AF control circuit 140 adds the correction amount in the AF correction amount storage unit 150 to the detected defocus amount, and calculates a corrected defocus amount, that is, information used for focus control. The correction amount in the AF correction amount storage unit 150 is determined with reference to the count numbers of the first counter 151 and the second counter 152. A method for determining the correction amount will be described later.

  This corrected defocus amount is converted into a driving amount of a focusing lens which is a part of the imaging optical system 103. Then, this focusing lens driving amount information is transmitted to the lens system control circuit 141 via the camera system control circuit 135.

  For the moving subject, the AF control circuit 140 takes into account the time lag from when the release button 120 is pressed until the actual imaging operation is started, and based on the prediction result of an appropriate lens stop position. Instructs the driving amount of the focusing lens. The camera system control circuit 135 causes the illumination unit 104 to emit light when it is determined that the subject brightness is low and sufficient focus detection accuracy cannot be obtained based on the result of metering the subject brightness by a photometry circuit (not shown). Illuminate the subject. At this time, the subject may be illuminated by a white LED (not shown) or a fluorescent tube provided in the camera body 101.

  When the lens system control circuit 141 receives the focusing lens drive amount information sent from the camera system control circuit 135, the lens system control circuit 141 moves the focusing lens to the optical axis via a drive mechanism (not shown) in the lens device 102 based on the drive amount information. Move in the direction of L1.

  When the AF control circuit 140 detects that the subject is in focus, this detection information is transmitted to the camera system control circuit 135. At this time, if the release button 120 is pressed, the imaging control is performed by the imaging system, the image processing system, and the recording / reproducing system as described above.

  The diaphragm adjusts the amount of light flux from the subject toward the image plane in response to a command from the lens system control circuit 141. The camera system control 135 and the lens system control circuit 141 are configured to be able to communicate with each other via the mount part electrical contact (communication unit) 102a on the interchangeable lens 102 side and the mount part electrical contact 101a on the camera body 101 side. Yes. Reference numeral 145 denotes a mirror driving mechanism for driving the half mirror 111 and the sub mirror 122 that constitute the optical path switching unit.

  1 to 5 show a more specific configuration of the camera system of the present embodiment. Note that only part of the interchangeable lens 102 is shown. In these drawings, operations of the half mirror 111 and the sub mirror 122 are mainly shown in time series. 1 to 5, the same members as those described in FIGS. 6 and 7 are denoted by the same reference numerals.

  In the figure, reference numeral 103 a denotes a lens located closest to the image plane among a plurality of lenses constituting the imaging optical system 103. Reference numeral 102b denotes a mount mechanism on the interchangeable lens 102 side, and 101b denotes a mount mechanism on the camera body 101 side.

  Reference numeral 164 denotes a condenser lens that serves as a light beam capturing window in the focus detection unit 121. Reference numeral 165 denotes a reflecting mirror, 166 denotes a re-imaging lens, and 167 denotes the above-described focus detection sensor (light receiving element).

  The light beam emitted from the imaging optical system 103 and reflected by the half mirror 111 in the second optical path state or the sub mirror 122 in the first optical path state enters the condenser lens 164. Thereafter, the light beam is deflected by the reflection mirror 165, and a secondary image of the subject is formed on the focus detection sensor 167 by the action of the re-imaging lens 166.

  The focus detection sensor 167 is provided with at least two pixel columns. Between the output signal waveforms of the two pixel columns, a relatively laterally shifted state is observed according to the imaging state of the subject image formed by the imaging optical system 103 on the focus detection region. The shift direction of the output signal waveform is reversed at the front and rear pins, and the principle of the phase difference detection method is to detect this phase difference (shift amount) including the shift direction using a method such as correlation calculation. is there.

  Reference numerals 109-1 to 109-3 denote lenses constituting the eyepiece 109 shown in FIG. Reference numeral 163 denotes an eyepiece shutter which is a light shielding member capable of moving back and forth with respect to the optical path of the optical viewfinder. The eyepiece shutter 163 is a member for avoiding an influence on imaging due to the light that has entered backward from the eyepiece lens 109 reaching the imaging element 106.

  The configuration of the mirror drive mechanism 145 will be described with reference to FIG. FIG. 3 shows a diagram when the camera is in the first optical path state described above.

  The half mirror 111 is held by a half mirror receiving plate (not shown). The half mirror receiving plate is provided with pins 173 and 174, and the half mirror 111 and the pins 173 and 174 are integrally movable through the half mirror receiving plate.

  Reference numeral 170 denotes a half mirror drive lever, and 171 denotes a half mirror support arm. The half mirror drive lever 170 is supported to be rotatable with respect to the rotation shaft 170a, and the half mirror support arm 171 is supported to be rotatable with respect to the rotation shaft 171a.

  The half mirror drive lever 170 is connected to a drive source via a power transmission mechanism (not shown), and can rotate around a rotation shaft 170a by receiving a drive force from the drive source. Further, the half mirror support arm 171 is connected to a structure having substantially the same shape on the opposite wall surface side of the mirror box via the connection portion 171b.

  A pin 173 provided on a half mirror receiving plate (not shown) is slidably engaged with a through hole 171c provided at the tip of the half mirror support arm 171. Thereby, the half mirror 111 can be rotated centering on the through-hole 171c via the half mirror receiving plate. Further, an urging force in the direction of arrow A is applied to an intermediate position between the pin 173 and the pin 174 in the half mirror receiving plate by a torsion spring (not shown).

  In the first optical path state shown in FIG. 3, the mirror stoppers 160 and 161 are in the state of entering the movement locus of the half mirror 111 outside the imaging optical path. In this state, the half mirror 111 is positioned in contact with the mirror stoppers 160 and 161 by receiving a biasing force in the direction of arrow A by the torsion spring. As a result, the half mirror 111 is placed obliquely on the photographing optical path.

  Here, the pin 173 does not contact the first cam surface 170b of the half mirror drive lever 170, and the pin 174 does not contact the second cam surface 170c of the half mirror drive lever 170.

  Further, the sub mirror 122 is located behind the half mirror 111 in a state where the rotation around the rotation shaft 125 is suppressed.

  In the above-described first optical path state, the light beam reflected by the half mirror 111 out of the light beam emitted from the imaging optical system 103 is guided to the optical viewfinder. Further, the light beam transmitted through the half mirror 111 is reflected by the sub-mirror 122 behind the half mirror 111 and guided to the focus detection unit 121.

  When the mirror stoppers 160 and 161 are retracted from the movement trajectory of the half mirror 111, the pin 173 comes into contact with the first cam surface 170b of the half mirror drive lever 170 by the biasing force in the direction of arrow A by a torsion spring (not shown). The pin 174 contacts the second cam surface 170c of the half mirror drive lever 170. This is the same when the half mirror drive lever 170 is rotated in the clockwise direction in FIG.

  Then, the pins 173 and 174 move along the first cam surface 170b and the second cam surface 170c, respectively, according to the rotation amount of the half mirror drive lever 170. Thereby, the attitude | position of the half mirror 111 changes.

  That is, the half mirror support arm 171 rotates in conjunction with the rotation of the half mirror drive lever 170. Then, the half mirror receiving plate connected to the half mirror drive lever 170 and the half mirror support arm 171 via the pins 173 and 174 is rotated, and the half mirror 111 is rotated with this.

  1 to 5 show the operations of the half mirror 111 and the sub mirror 122. FIG. FIG. 1 shows a second optical path state, and FIG. 2 shows a transition process from the first optical path state to the second optical path state. FIG. 4 shows a transition process from the first optical path state to the third optical path state, and FIG. 5 shows the third optical path state.

  When in the first optical path state (FIG. 3), the half mirror 111 and the sub mirror 122 guide the light beam emitted from the subject emitted from the imaging optical system 103 to the optical viewfinder and the focus detection unit 121 as described above. Act on.

  In the second optical path state (FIG. 1), the half mirror 111 acts to guide the light beam emitted from the imaging optical system 103 to the image sensor 106 and the focus detection unit 121. Furthermore, when in the third optical path state (FIG. 5), the half mirror 111 and the sub mirror 122 are retracted from the imaging optical path.

  Next, an imaging sequence in the camera system of the present embodiment will be described with reference to FIG. The sequence in FIG. 8 is mainly executed by the camera system control circuit 135 and the AF control circuit 140 in accordance with a computer program stored therein.

  In step S1, the process waits until the main switch 119 is operated (ON), and the operation proceeds to step S2. In step S <b> 2, current is supplied (activated) to various electric circuits in the camera body 101.

  In step S3, the set finder mode is determined. If the OVF mode is set, the process proceeds to step S4A. If the EVF mode is set, the process proceeds to step S4B.

  In step S4A, the information display unit 180 in the optical viewfinder is driven to display predetermined information on the display unit provided in the optical viewfinder. In this OVF mode, a subject image can be observed through the eyepiece lens 109 together with the predetermined information.

  In step S4B, an image or predetermined information is displayed on the display unit 107. In the EVF mode, the subject image can be observed together with the predetermined information via the display unit 107.

  Here, when the operation detection circuit 136 detects that the finder mode changeover switch 123 is operated, the finder mode is switched. For example, when the OVF mode is switched to the EVF mode, the subject image is displayed on the display unit 107 by driving the imaging system and the image processing system.

  In step S5, the process waits until it is detected that the release button 120 has been half-pressed based on the output of the operation detection circuit 136, that is, until SW1 is turned on, and SW1 is turned on. Proceed to

  In step S <b> 6, subject brightness is measured (photometry), and the focus detection unit 121 performs a focus detection operation.

  The camera system control circuit 135 calculates an exposure value (shutter speed and aperture value) based on the photometric result. Further, the AF control circuit 140 as the focus information generation unit detects a phase difference between signals corresponding to the two images from the focus detection sensor 167, and calculates a defocus amount from the phase difference. At that time, the focus detection result to be described later is corrected, and the above-mentioned “defocus amount after correction” is calculated. Specifically, a focus detection result correction amount, which will be described later, is added to or subtracted from the defocus amount obtained from the phase difference. After calculating the post-correction defocus amount in this way, the focusing lens drive amount is calculated based on the post-correction defocus amount.

  It should be noted that correcting the defocus amount is not only generating a new defocus amount (post-correction defocus amount), and in this sense, correcting in this embodiment can be rephrased as generating a new one. it can.

  Then, the focusing lens of the imaging optical system 103 is driven by focus control by the AF control circuit 140 and the lens system control circuit 141. The lens system control circuit 141 drives the aperture based on the calculated aperture value and adjusts the amount of light. Thereafter, the focus detection operation may be performed again for in-focus confirmation. If it is determined that the in-focus state is not achieved, the calculation of the focusing lens drive amount and the driving of the focusing lens may be performed again.

  In step S7, based on the output of the operation detection circuit 136, it is determined whether or not the release button 120 is fully pressed, that is, whether or not the SW2 is in an ON state. If SW2 is in the ON state, the process proceeds to step S8. If SW2 is in the OFF state, the process returns to step S5.

  In step S8, the half mirror 111 and the sub mirror 122 are brought into a state in which the second sensor output detection operation can be performed via the mirror driving mechanism. That is, the optical path switching unit is switched to the first optical path state shown in FIG. 3 in the EVF mode and to the second optical path state shown in FIG. 1 in the OVF mode.

  In step S9, the half mirror 111 and the sub mirror 122 are switched to the third optical path state (FIG. 5).

  In step S10, the shutter 113 is operated based on the previously calculated shutter speed.

  In step S11, the image sensor 106 is exposed to accumulate charges. Here, the accumulated charge is read out as a signal and processed as a high-definition image by the image processing system.

  In step S12, the exposure of the image sensor 106 is finished and the shutter is closed.

  In step S13, the half mirror 111 and the sub mirror 122 are returned to the first or second optical path state according to the OVF mode or the EVF mode.

  In step S14, the current optical path state is determined by determining the finder mode. If it is the OVF mode, the process proceeds to step S15A, and if it is the EVF mode, the process proceeds to step S15B.

  In steps S15A and 15B, the number of integrated operations is counted corresponding to the current optical path state. In step S15A, the number of integration operations to the standby position of the half mirror 111 and the sub mirror 122 in the OVF mode (that is, the number of integration transitions to the first state after shooting) is counted. Also, in step S15B, the number of cumulative operations to the standby position of the half mirror 111 and the sub mirror 122 in the EVF mode (that is, the number of cumulative transitions to the second state after shooting) is counted.

  More specifically, in step S15A, N + 1 is substituted for the cumulative operation number N stored in the first counter 151 shown in FIG. 7, and in step S15B, the cumulative operation stored in the second counter 152 is stored. Substitute M + 1 for the number of times M. Based on the count numbers stored in the first and second counters 151 and 152, when the focus detection is performed in the next step S6, the result is corrected. The calculation of the correction amount will be described later.

   Note that the above-described imaging sequence is a sequence in the case of performing imaging with priority on the focusing accuracy, but in this embodiment, the sequence for performing imaging with priority on shortening the release time lag is the focus adjustment mode selection switch 126 (see FIG. 7). ).

   Further, the camera of the present embodiment performs focus detection by the phase difference detection method in the focus detection unit 121 even when an image acquired using the image sensor 106 is monitored on the display unit 107 (EVF mode). Can do. Thereby, in the EVF mode, it is possible to perform a high-speed focus adjustment operation as compared with the case where focus detection is performed by the contrast detection method (TV-AF method).

  Next, the finder mode switching operation will be described. While the electric circuit in the camera is operating, the state of each operation switch is detected via the operation detection circuit 136. When it is detected that the finder mode changeover switch 123 has been operated, the finder mode (OVF mode and EVF mode) switching operation is started (step S3 in FIG. 8).

  FIG. 9 is a flowchart for explaining the finder mode switching operation. The sequence of FIG. 9 is mainly executed by the camera system control circuit 135 in accordance with a computer program stored therein.

  In step S100, the current finder mode is detected. When the finder mode changeover switch 123 is operated from the OVF mode to the EVF mode, the process proceeds to step S101. On the other hand, when the finder mode changeover switch 123 is switched from the EVF mode to the OVF mode, the process proceeds to step S111.

  First, switching from the OVF mode to the EVF mode will be described. In the OVF mode, the optical path switching unit composed of the half mirror 111 and the sub mirror 122 is in the first optical path state (FIG. 3). In the EVF mode, since the subject light is not guided to the optical viewfinder, the eyepiece shutter 163 is closed by the eyepiece driving circuit 143 and the actuator 144 in step S101. That is, the eyepiece shutter 163 is caused to enter the finder optical path between the lens 109-2 and the lens 109-3 constituting the eyepiece lens 109.

  This is to prevent the photographer from misunderstanding that the subject image cannot be seen through the eyepiece lens 109 when the EVF mode is set. Another reason for this is to prevent the occurrence of a ghost due to the back incident light from the optical viewfinder entering the image sensor 106.

  In step S102, the information display unit 180 in the finder is driven to turn off the information display in the optical finder. This is because, since the eyepiece shutter 163 has already been closed in step S101, the photographer cannot see this display even if information is displayed in the optical viewfinder. Thereby, power consumption can be reduced and consumption of the battery can be suppressed.

  In step S103, by operating the mirror driving mechanism 145, the sub mirror 122 is retracted to the lower part of the mirror box in preparation for shifting the half mirror 111 to the second optical path state (FIG. 1) (FIG. 1).

  In step S104, the mirror stoppers 160 and 161 are retracted from the movement locus of the half mirror 111.

  After the mirror stoppers 160 and 161 are retracted, in step S105, the mirror driving mechanism 145 rotates the half mirror driving lever 170 in the counterclockwise direction in FIG. As a result, the half mirror 111 enters the second optical path state (FIG. 1) through the state shown in FIG. 2 by receiving a biasing force in the direction of arrow A by a torsion spring (not shown).

  When the half mirror 111 is in the second optical path state, a part of the light beam from the imaging optical system 103 is reflected by the half mirror 111 and guided to the focus detection unit 121. Further, the remaining light flux passes through the half mirror 111 and travels toward the image sensor 106 side.

  In the second optical path state, the half mirror 111 is positioned in contact with the mirror stoppers 175 and 176 disposed outside the photographing optical path by receiving a biasing force in the direction of arrow A by the torsion spring. At this time, the pin 173 does not contact the first cam surface 170b of the half mirror drive lever 170, and the pin 174 does not contact the second cam surface 170c of the half mirror drive lever 170.

  In step S106, since the optical path state shifts from the OVF mode to the EVF mode, M + 1 is substituted for the cumulative operation count M stored in the second counter 152. As a result, the sum of the number of integrated operations to the second optical path state of the half mirror 111 and the sub mirror 122 after photographing and the number of integrated operations to the second optical path state for switching the finder mode is the second counter. Stored in 152.

  The position of the reflecting surface of the half mirror 111 is substantially the same as the position where the reflecting surface of the sub mirror 122 is located in the first optical path state. Thereby, the deviation between the reflected light guided to the focus detection unit 121 by the sub mirror 122 in the first optical path state and the reflected light guided to the focus detection unit 121 by the half mirror 111 in the second optical path state is minimized. Therefore, the position of the focus detection area can be hardly changed.

  Here, the focus position of the subject image formed by the light transmitted through the half mirror 111 being imaged on the image sensor 106 is slightly shifted from the focus position when the subject light does not pass through the half mirror 111. . For this reason, in step S107, the focus correction mode is activated in order to correct the shift of the focus position.

  In the first optical path state, the camera system control circuit 135 sharpens the subject image on the image sensor 106 when the half mirror 111 and the sub mirror 122 are retracted from the photographing optical path (when the third optical path state is reached). The focusing lens drive amount is calculated so as to form an image.

  On the other hand, when the focus correction mode is on in the second optical path state, the focusing lens is driven so that the subject image that is transmitted through the half mirror 111 and projected onto the image sensor 106 is sharply formed. Correct the amount. As a result, when the focus correction mode is set in the second optical path state, the focusing lens drive position in the second optical path state is in focus in the third optical path state by an amount corresponding to the correction of the focusing lens drive amount. Deviation from position.

  When the EVF mode is set, the release button 120 is fully pressed to start the imaging operation, and when switching from the second optical path state to the third optical path state, the front curtain of the shutter 113 is synchronized with this. Charge the drive mechanism. That is, the shutter 113 is closed. Further, the focusing lens is driven to the in-focus position in the third optical path state by the amount that the focus position of the subject image is corrected by the focus correction mode. Thereafter, the image sensor 106 is exposed by operating the shutter 113 at the calculated shutter speed.

  With this configuration, the focus state is accurately confirmed based on the image displayed on the display unit 107 in the second optical path state, and then an image in focus in the third optical path state is captured. be able to.

  In step S108, the front curtain of the shutter 113 is opened and the image sensor 116 is continuously exposed, and a through image for display on the display unit 107 can be acquired.

  In step S109, the display unit 107 is powered on.

  In step S110, display of the through image on the display unit 107 is started, and the process returns to step S100.

  Next, a case will be described in which the process proceeds to step S111 in order to switch from the EVF mode to the OVF mode by determining the finder mode in step S100.

  In the EVF mode in the initial state, the optical path system composed of the half mirror 111 and the sub-mirror 122 is in the second optical path state (FIG. 1), and through image display is performed on the display unit 107 as described above.

  In step S111, the power of the display unit 107 is turned off, and the through image acquisition by the image sensor 106 is stopped.

  In step S112, the rear curtain of the shutter 113 is moved to close the shutter 113, and the front curtain / rear curtain drive mechanism is charged in preparation for imaging.

  In step S <b> 113, the mirror stoppers 160 and 161 are retracted from the movement locus of the half mirror 111 in order to enable the movement of the half mirror 111.

  In step S114, the half mirror drive lever 170 is rotated in the clockwise direction in FIG. 1, and the half mirror 111 and the sub mirror 122 are in the state of FIG. 2, the state of FIG. 3, the state of FIG. 4, and the state of FIG. (Third optical path state).

  When the half mirror drive lever 170 is rotated in the clockwise direction, the pin 174 is pushed and moved into the second cam surface 170c, and the pin 173 is pushed and moved into the first cam surface 170b. As a result, the half mirror support arm 171 rotates clockwise about the rotation shaft 171a, and the half mirror 111 rotates clockwise about the pin 173.

  In step S115, the mirror stoppers 160 and 161 are inserted into the movement locus of the half mirror 111.

  Since the mirror stoppers 160 and 161 are inserted after the half mirror 111 is moved to the third optical path state, there is no collision with the half mirror 111 when the mirror stoppers 160 and 161 are inserted. For this reason, it is possible to increase the mechanical reliability when switching the position of the half mirror 111 (when switching between the OVF mode and the EVF mode).

  In this embodiment, the half mirror 111 is moved to the third optical path state. However, since the mirror stoppers 160 and 161 do not have to collide with the half mirror 111, the half mirror 111 corresponds to the third optical path state. You may move to the vicinity of the position to do.

  In step S116, the half mirror drive lever 170 is rotated counterclockwise in FIG. As a result, the half mirror 111 is moved from the third optical path state (FIG. 5) to the first optical path state (FIG. 3) through the state of FIG. At this time, the half mirror 111 is brought into contact with the mirror stoppers 160 and 161 by receiving a biasing force of a spring (not shown) provided in the mirror driving mechanism 145.

  In step S117, since the optical path state shifts from the EVF mode to the OVF mode, N + 1 is substituted for the integrated operation count N stored in the first counter 151. As a result, the sum of the number of integrated operations to the first optical path state of the half mirror 111 and the sub mirror 122 after photographing and the number of integrated operations to the first optical path state for switching the finder mode is the first counter. 151.

  In step S118, the eyepiece shutter 163 is opened.

  In step S119, based on the output from the operation detection circuit 136, it is determined whether or not the manual (M) focus mode is set. If the manual focus mode is selected, the process proceeds to step S107. If the manual focus mode is selected instead of the manual focus mode, the process proceeds to step S120.

  In the manual focus mode, it is not necessary to operate the focus detection unit 121, and the background blur can be grasped more accurately by using an electronic image (through image) than by an optical viewfinder. For this reason, the process proceeds to step S107 in which a through image display is performed on the display unit 107.

  In step S120, the sub mirror 122 is set at a predetermined position so as to guide subject light to the focus detection unit 121. That is, as shown in FIG. 5, the sub-mirror 122 housed in the lower part of the mirror box is moved behind the half mirror 111 by rotating about the rotation shaft 125 (FIG. 3).

  In step S121, the information display unit 180 in the optical viewfinder is driven to display predetermined information in the viewfinder. Then, the process returns to step S100.

  According to the present embodiment, in using the camera, the number of times of the operation for shifting to the first and second optical path states, that is, the return operation after photographing and the operation for switching to the finder mode is calculated for each optical path state. Can be stored separately. Thereby, the correction of the focus detection result to be described later can be performed corresponding to each optical path state.

  Next, a description will be given of a method of correcting the focus detection results in the first and second optical path states in accordance with the number of times of integration operation representing the change with time of the camera.

  FIG. 10A shows the relationship between the cumulative number of operations for the first and second optical path states and the correction amount of the focus detection result (focus detection signal). The total number of operations here refers to the sum of the total number of operations to each optical path state after shooting (total number of release times) and the total number of operation times to each optical path state for switching to the viewfinder mode (total number of times to switch the viewfinder mode). is there.

  One cause of the change in the focus detection result due to the use of the camera is a change in the optical path length due to deformation or wear of parts related to driving of the optical member arranged in the optical path of the light beam guided to the focus detection unit 121.

  In this embodiment, when shifting to the first optical path state, wear of the mirror stoppers 160 and 161 for stopping and positioning the half mirror 111 and wear of a stopper (not shown) for stopping and positioning the sub mirror 122 are performed. Etc. occur. In addition, when moving to the second optical path state, wear of mirror stoppers 175 and 176 for stopping and positioning the half mirror 111 occurs.

  As described above, when the parts to be deformed or worn are different depending on the optical path state to be transferred, it is necessary to change the correction amount of the focus detection result in the optical path state after the shift.

  In the present embodiment, as described above, it is possible to store the cumulative operation counts for the first and second optical path states. For this reason, the correction amount (or the calculation formula) of the focus detection result with respect to the number of times of cumulative operation in each optical path state is stored in advance in the AF correction amount storage unit 150, thereby correcting the focus detection result corresponding to the optical path state. It can be performed.

  In addition, wear of the rotating shafts 170a and 171a occurs when the state shifts to either the first optical path state or the second optical path state. When there is a part that wears regardless of the optical path state to be shifted in this way, even if the transition to one optical path state is not performed, the one of the above-mentioned ones increases as the number of integrated operations to the other optical path state increases. There is a possibility that the deviation of the focus detection result in the optical path state becomes large.

  For this problem, the correction amount of the focus detection result in each optical path state is set in advance according to the sum (N + M) of the count number N of the first counter 151 and the count number M of the second counter 152. By storing it, it is possible to correct an appropriate focus detection result.

  Specifically, first, it is determined whether or not the sum (N + M) of the count number N of the first counter 151 and the count number M of the second counter 152 is not more than a certain threshold value. When it is less than the threshold value, the correction amount of the focus detection result in each optical path state is calculated using the data of the correction amount of the focus detection result with respect to the number of integration operations for each optical path state shown in FIG. 10A. On the other hand, when the number is larger than the threshold value, the correction amount of the focus detection result in each optical path state is calculated using the data of the correction amount of the focus detection result with respect to the number of times of cumulative operation in each optical path state shown in FIG.

  Note that the timing for discriminating between the sum of the count numbers (N + M) and the threshold value may be performed together with the finder mode identification in step S3 in the flowchart shown in FIG.

  Further, in this embodiment, the cumulative operation count counted by the first and second counters 151 and 152 is the sum of the cumulative release count and the cumulative finder mode switching count. However, generally, since it is considered that the number of photographing operations (release operations) occupies the majority, the cumulative number of operations counted by each counter may be only the cumulative release number.

  As described above, the focus detection result corresponding to each optical path state can be corrected regardless of the deviation of the usage frequency between the first and second optical path states.

  Next, as a modification of the present embodiment, a method for calibrating variation in focus detection results depending on the optical path state will be described.

  FIG. 11A and FIG. 11B show the number of counts in the first and second counters 151 and 152 (the number of integrated operations for each of the first and second optical path states) stored in advance in the AF correction amount storage unit 150. ) And the correction amount of the focus detection result. The relationship between the accumulated number of operations stored in advance and the correction amount of the focus detection result is indicated by a thick solid line, and the number of integration operations appropriate for a specific camera individual and the correction amount of the focus detection result (hereinafter referred to as individual correction amount) Is shown by a thin broken line. In these figures, the relationship between the number of integrated operations for three individual cameras and the individual correction amount of the focus detection result is shown.

  As shown in these figures, the variation in the individual correction amount of the focus detection result among the individual cameras increases as the number of integration operations increases. For example, when the actuator is operated intensively for a short period of time and when it is operated at an appropriate interval, the degree of wear and fatigue of the components that make up the drive mechanism are different even if the cumulative number of operations is the same, and the focus detection results associated therewith The amount of correction is also different. For this reason, the reliability between the accumulated number of operations stored in advance and the correction amount decreases as the number of accumulated operations increases.

  That is, as in the present embodiment, when focus detection is performed in a plurality of optical path states, the number of integrated operation times (count numbers N and M of the first and second counters 151 and 152) in each optical path state is large or small. Depends on the reliability of the correction amount.

  When focus detection is performed on the same subject, if the count number M of the second counter 152 is larger than the count number N of the first counter 151, the focus detection result in the first optical path state Is more reliable. In this embodiment, when calibrating so as to reduce the deviation of the focus detection result between a plurality of optical path states, the accumulated number of times of operation for each optical path state is stored, and the magnitude is compared in each optical path state. This improves the reliability of the calibration of the focus detection result.

  FIG. 12 shows a sequence when the focus detection result calibration operation is performed during the finder mode switching operation. In this flowchart, steps that perform the same operations as those in the flowchart of FIG. 9 are denoted by the same step numbers as in FIG.

  When switching the finder mode from the OVF mode to the EVF mode, Step S200 is executed between Step S102 and Step S103.

  In step S200, focus detection is performed once in the first optical path state, and the result is stored. Then, after switching to the EVF mode (second optical path state), for example, between step S107 and step S108, focus detection is performed in the second optical path state in step S201, and the result is stored.

  When switching the finder mode from the EVF mode to the OVF mode, focus detection is performed once in the second optical path state in step S210 between step S112 and step S113, and the result is stored. Then, after switching to the OVF mode (first optical path state), for example between step S120 and step S121, in step S211, focus detection in the first optical path state is performed, and the result is stored.

  Further, after step S110 or S121, in step S220, a difference value (or a value obtained from a specific calculation from the difference value) between the two focus detection results performed in each finder mode is used as an amount of correction. It is stored in the quantity storage unit 150.

  Subsequently, in step S221, the number of counts of the first and second counters 151 and 152 is determined. If the count number N of the first counter 151 is larger, in step S222A, the focus detection result (first focus detection result) in the first optical path state performed in step S200 or S211 is set to the correction amount. Use to correct. If the count number M of the second counter 152 is larger, in step S222B, the focus detection result (second focus detection result) in the second optical path state performed in step S201 or S210 is corrected as described above. Correct with the amount.

  In the description of this modification, correction of the focus detection result is performed every time the finder mode is switched. However, the correction amount is accumulated during a plurality of finder mode switching, and after performing statistical processing, the focus detection is performed. The result may be corrected. Further, the correction of the focus detection result may be performed not only in accordance with the finder mode switching operation but also by providing a focus detection result calibration mode and setting the mode.

  As described above, in the present embodiment, focus detection is possible in a plurality of optical path states, and in an imaging apparatus that shifts from each optical path state to a photographing state, an integration operation is performed in advance according to the number of integration operations to each optical path state. The focus detection result is corrected using the correction amount stored corresponding to the number of times. Accordingly, it is possible to correct the shift of the focus detection result that changes depending on the number of times of integration operation to each optical path state, and maintain the accuracy of focus control in each optical path state.

  In addition, according to the frequency of use of a plurality of optical path states and the amount of empirical change in the focus detection results accompanying use, the focus detection results in other optical path states are matched with the focus detection results in a specific optical path state. By correcting, it is possible to suppress variation in accuracy of the focus detection result due to the temporal change between the individual imaging devices.

  In the above embodiment, the case where the defocus amount as the focus detection result is corrected has been described. However, the present invention is not limited to this. For example, the focusing lens driving amount calculated based on the defocus amount can be corrected. The correction target in the present invention may be information used for focus control including the defocus amount and the focusing lens drive amount.

1 is a cross-sectional view illustrating a configuration of a camera system (second optical path state) that is Embodiment 1 of the present invention. Sectional drawing which shows the structure of the camera system of the Example (during transition to the 1st optical path state from 2nd). FIG. 3 is a cross-sectional view illustrating a configuration of a camera system (first optical path state) according to the embodiment. Sectional drawing which shows the structure of the camera system (during the transition to the 1st to 3rd optical path state) of an Example. Sectional drawing which shows the structure of the camera system (3rd optical path state) of an Example. 1 is a schematic diagram illustrating a schematic configuration of a camera system according to an embodiment. FIG. 1 is a block diagram illustrating an electrical configuration of a camera system according to an embodiment. 6 is a flowchart illustrating an imaging sequence in the camera system of the embodiment. 6 is a flowchart showing a finder mode switching operation sequence in the camera system of the embodiment. The figure which shows the relationship between the frequency | count of integration transfer to the 1st and 2nd optical path state in the camera system of an Example, and the correction amount of a focus detection result. The figure which shows the relationship between the frequency | count of integration transfer to the 1st and 2nd optical path state in the camera system of an Example, and the correction amount of a focus detection result. The figure which shows the relationship between the frequency | count of integration transfer to the 1st and 2nd optical path state in the camera system of an Example, the correction amount of a focus detection result, and this relationship by a camera individual difference. The figure which shows the relationship between the frequency | count of integration transfer to the 1st and 2nd optical path state in the camera system of an Example, the correction amount of a focus detection result, and this relationship by a camera individual difference. 9 is a flowchart showing a finder mode switching operation sequence in a camera system as a modification of the embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 103 Imaging optical system 106 Image pick-up element 107 Display unit 109 Eyepiece lens 111 Half mirror 121 Focus detection unit 122 Submirror 140 AF control circuit 150 AF correction amount memory | storage part 167 Focus detection sensor (light receiving element)

Claims (7)

An image sensor that photoelectrically converts a subject image;
A viewfinder optical system that enables observation of the subject image;
A focus detection unit that detects a focus state using a light beam from a subject; and
An optical path switching unit used for switching the luminous flux from the subject;
A first state in which the light beam from the subject is guided to the finder optical system and the focus detection unit; a second state in which the light beam from the subject is guided to the image sensor and the focus detection unit; A mechanism for switching to a third state located outside the optical path to the image sensor of the luminous flux;
An image pickup apparatus comprising: an accumulation storage means for storing the number of accumulation transitions to each of the first and second states.   Focus information for generating information used for focus control based on at least one of the number of times of integration transition to each of the first and second states stored in the integration storage means and the detection result by the focus detection unit The imaging apparatus according to claim 1, further comprising a generation unit.   The focus information generation means includes a sum of the number of integration transitions to each of the first and second states stored in the integration storage means, and the number of integration transitions to each of the first and second states. The imaging apparatus according to claim 2, wherein information used for the focus control is generated based on one of them and a detection result by the focus detection unit. The focus information generation unit selects data for generating information used for the focus control in accordance with the sum of the number of integration transitions to each of the first and second states stored in the integration storage unit. ,
Information used for the focus control is generated based on a value corresponding to one of the number of integration transitions to each of the first and second states in the selected data and a detection result by the focus detection unit. The imaging apparatus according to claim 3, wherein:   The focus information generation means uses the number of integration transitions to each of the first and second states and the detection result by the focus detection unit in one of the first and second states, The imaging apparatus according to claim 2, wherein information relating to focus control based on a detection result by the focus detection unit in the other of the first and second states is generated. The imaging apparatus performs a first focus detection operation by the focus detection unit in the first state and a second focus detection operation by the focus detection unit in the second state,
The focus information generating means
Obtaining a difference value between detection results of the first and second focus detection operations;
Of the first and second focus detection operations, the detection result by the focus detection operation performed in the smaller state of the number of integration transitions to each of the first and second states and the difference value 6. The imaging apparatus according to claim 5, wherein information on the focus control is generated based on the information. The imaging device according to any one of claims 1 to 6,
An imaging system comprising: a lens device that can be attached to and detached from the imaging device.