JP4194577B2 - Imaging device - Google Patents

Description

  The present invention relates to an imaging apparatus having a focus adjustment function of an objective lens and an observation function of an object image formed by the objective lens.

  When an object is observed through an optical viewfinder (OVF) in a single-lens reflex camera, which is one of the optical devices, a light beam emitted from the objective lens is reflected on the optical path behind (image plane side) the objective lens. The optical path is changed by reflecting with a reflecting mirror disposed in the optical path and led to an optical viewfinder including a pentaprism. Thereby, the object image formed by the light beam that has passed through the objective lens can be viewed as a normal image. At this time, the reflection mirror is provided obliquely on the photographing optical path.

  On the other hand, when the objective lens is used as a photographing lens (when photographing), the reflecting mirror instantaneously retreats from the photographing optical path, so that the photographing light flux that has passed through the objective lens becomes an imaging medium (such as a film or a CCD). The image is formed on the imaging device. When the photographing is completed, the reflection mirror is instantaneously provided on the photographing optical path.

  In a digital camera, a subject image is exposed to an image sensor such as a CCD or CMOS sensor for a desired time in response to a press operation of a release button, and an image signal representing one still image obtained by photoelectric conversion is converted into a digital signal. To do. A predetermined format image signal is obtained by performing predetermined processing such as YC processing on the converted digital signal.

  A digital image signal representing a captured image is recorded in a semiconductor memory for each image. The recorded image signal is read at any time and displayed on the display unit of the camera, reproduced as a printable signal, or output and displayed on a display device or the like.

  Among the cameras described above, there is a single-lens reflex digital camera that can manually select a focus adjustment operation by a phase difference detection method and a focus adjustment operation by a contrast detection method (see, for example, Patent Document 1).

  In a single-lens reflex digital camera equipped with an optical viewfinder and an electronic viewfinder (EVF; Electric View Finder), a phase difference detection method based on a light beam reflected by the mirror when the reflecting mirror is obliquely arranged on the photographing optical path In some cases, contrast detection is performed using the output of an image sensor that receives a photographic light beam when the reflecting mirror is retracted from the photographic optical path (see, for example, Patent Document 2).

  In the camera disclosed in Patent Document 2, the captured image can be electronically displayed while performing the focus adjustment based on the output of the image sensor even when the reflection mirror is at a position retracted from the imaging optical path. Therefore, the photographer can take an image while confirming the focus state of the image electronically displayed on the organic EL display, for example.

  On the other hand, in the focus control, there is a focus adjustment device having a configuration in which a step is provided on the light detection surface of the image sensor in order to speed up the determination of the focus direction (drive direction of the photographing lens) (for example, Patent Document 3). reference). That is, a plurality of image signals are collected by changing the optical path length by a minute distance, and the focusing direction is determined based on the collected image signals. Then, the imaging lens is moved to the in-focus position in the determined in-focus direction.

In addition, there is a camera system including a phase difference detection type focus detection device in each of the lens device and the camera body (see, for example, Patent Document 4). Note that, for example, Patent Document 5 proposes a focus adjustment state detection method using a phase difference detection method.
JP 2001-275033 A (paragraph number 0048, FIG. 4) JP 2001-125173 A (paragraph numbers 0064 and 0066, FIGS. 8 and 9) JP 2001-215406 A (paragraph number 0034, FIGS. 6 and 7) Japanese Unexamined Patent Publication No. 2000-162494 (paragraph numbers 0022 and 0023, FIG. 2) Japanese Patent Publication No. 5-88445 (pages 3 and 4)

  The cameras disclosed in Patent Documents 1 and 2 described above perform focus adjustment by a contrast detection method, but this method has a problem that it takes time to reach a focused state.

  Focus adjustment using the contrast detection method determines the sharpness of the object image formed by the imaging optical system by evaluating it with a predetermined function based on the output of the imaging device, and the imaging optical so that the function value takes an extreme value. It adjusts the optical axis position of the system. As the evaluation function, an absolute value of the difference between the luminance signals of adjacent pixels is added within the focus detection area, a square of the difference between the luminance signals of adjacent pixels is added within the focus detection area, or R, There are some which process the difference between adjacent pixel signals in the same way for each of the G and B image signals.

  In focus adjustment using such a contrast detection method, since an evaluation function value is obtained while slightly moving the optical axis position of the imaging optical system (focusing lens), it takes a considerable time to reach the in-focus state. .

  On the other hand, in the focus adjustment device disclosed in Patent Document 3 described above, the focusing operation is speeded up. However, since a short optical path length pixel and a long optical path length pixel are mixed, a high-quality image is obtained. I can't. Here, if the optical path length difference between the short optical path length pixel and the long optical path length pixel is shortened, the image quality can be improved, but the direction determination in the focus control becomes difficult. Therefore, the focus adjustment device cannot achieve both high-speed focus control and image quality improvement.

  Since the camera system disclosed in Patent Document 4 described above includes a phase difference detection type focus detection device, the defocus amount can be known by a single focus detection operation. For this reason, if the focusing lens of the objective lens is driven based on the defocus amount, usually one lens drive is required until the in-focus state is reached, and extremely high speed focus adjustment is possible.

  In the above camera system, during continuous shooting, the reflecting mirror is kept retracted from the shooting optical path, the focal plane shutter is fully opened, and the focus detection operation is performed by the focus detection unit in the lens apparatus. Therefore, even when the reflecting mirror is in the retracted state and the focus detection unit in the camera body is inoperative, high-speed focus adjustment can be performed based on focus detection in the focus detection unit in the lens device. .

  However, in the camera system disclosed in Patent Document 4 described above, the reflection mirror is retracted from the photographing optical path when the light beam is guided to the image sensor, and the focus detection is performed in this state. In the apparatus, a focus detection unit different from the focus detection unit in the camera body is provided. For this reason, there exists a problem that a camera system will enlarge and it will become expensive.

An imaging device according to the present invention includes an imaging device that photoelectrically converts an object image formed by a light beam from a photographing lens, and a focal point that detects a focus adjustment state of the photographing lens by a phase difference detection method. An image acquired using a detection unit , a finder optical system that guides the light beam from the photographic lens, a first mirror that reflects part of the light beam from the photographic lens and transmits the remainder, and an output from the image sensor Image display means for displaying data . The first mirror guides the light beam reflected by the first mirror to the finder optical system and guides the light beam transmitted through the first mirror to the focus detection unit, and the light beam reflected by the first mirror. Is switched to the second state in which the light beam transmitted through the first mirror is guided to the image sensor. Then, the image data acquired using the output from the image sensor when the first mirror is in the second state is displayed by the image display means .

According to the present invention, in the first state, the first mirror that guides the light beam from the photographing lens to the finder optical system is switched to the second state, so that the light beam is guided to both the focus detection unit and the image sensor. Can do. That is, the light beam-out guide to the imaging device in the second state, even in a state of displaying the image data acquired by using the output from the image sensor to the image display means, the focus detection unit provided in the imaging apparatus The focus can be detected by Therefore, it is not necessary to provide a focus detection unit outside the imaging device (for example, inside the lens device). In addition, the focus adjustment operation can be performed quickly by focus detection by the phase difference detection method.

  Examples of the present invention will be described below.

  A camera system that is Embodiment 1 of the present invention will be described with reference to FIGS.

  FIG. 6 is a side sectional view showing a schematic configuration of the camera system according to the present embodiment. The camera system of the present embodiment is a single-plate digital color camera using an image sensor such as a CCD or CMOS sensor, and drives an image sensor continuously or once to generate an image signal representing a moving image or a still image. obtain. Here, the image sensor is an area sensor of a type that converts received light into an electrical signal for each pixel, accumulates charges according to the amount of light, and reads the accumulated charges.

  In FIG. 6, reference numeral 101 denotes a camera body, in which members described below are arranged so that photographing can be performed. Reference numeral 102 denotes a lens device which has an imaging optical system 103 therein and is detachable from the camera body 101. The lens device 102 is electrically and mechanically connected to the camera body 101 via a known mount mechanism.

  A plurality of lens devices 102 having different focal lengths can be attached to and detached from the camera body 101, and shooting screens with various angles of view can be obtained by replacing the lens devices.

  The lens device 102 has a drive mechanism (not shown), and this drive mechanism performs focus adjustment by moving a focusing lens, which is a part of the imaging optical system 103, in the direction of the optical axis L1. Here, the focusing lens may be formed of a flexible transparent elastic member or a liquid lens, and the focus adjustment may be performed by changing the refractive power by changing the interface shape.

  Further, in the lens device 102, a diaphragm (not shown) for adjusting the light quantity of the photographing light flux by changing the opening area of the light passage opening and a drive mechanism (not shown) for driving the diaphragm are arranged. .

  Reference numeral 106 denotes an image sensor housed in a 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 of the object image is not transmitted to 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 formed with an infrared cut filter.

  An object image captured by the image sensor 106 is displayed on a display unit (image display means) 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.

  The image sensor 106 is a CMOS process compatible sensor (CMOS sensor) which is one of amplification type solid-state image sensors. One of the features of the CMOS sensor is that the MOS transistor of the area sensor part and peripheral circuits such as an image sensor drive circuit, AD converter circuit, and image processing circuit can be formed in the same process, so the number of masks and process steps are compared with those of a CCD. It can be greatly reduced. 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 a display image output operation and a high-definition image output operation using the above-described features.

  A half mirror (first mirror) 111 guides a part of the light beam from the imaging optical system 103 to the finder optical system (penta prism 112 and eyepiece lens 109) and transmits the remaining light beam. One optical path is divided into two optical paths. That is, at least a part of the half mirror 111 is a transmission region that transmits the light beam. This half mirror 111 is a movable type, and is obliquely installed on the photographing optical path (on L1) or retracted from the photographing optical path. Reference numeral 105 denotes a focusing screen arranged on the planned image plane of the object image. Reference numeral 112 denotes a pentaprism that reflects the light beam from the half mirror 111 a plurality of times (converts it into an erect image) and guides it to the eyepiece lens 109.

  Reference numeral 109 denotes an eyepiece for observing an object image formed on the focusing screen 105, and actually includes three lenses (109a, 109b, and 109c in FIG. 1) as described later. The focusing screen 105, the pentaprism 112, and the eyepiece lens 109 constitute a finder optical system.

  The half mirror 111 has a refractive index of about 1.5 and a thickness of 0.5 mm. A movable sub-mirror (second mirror) 122 is provided behind the half mirror 111 (on the image sensor 106 side), and the light beam near the optical axis L1 out of the light beam transmitted through the half mirror 111 is a focus detection unit. Reflected toward 121.

  The sub mirror 122 is rotatable around a rotation shaft 125 described later, and interlocks with the movement of the half mirror 111. The sub mirror 122 is housed in a lower part of a mirror box 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 movable illumination unit that irradiates an object with illumination light. The movable illumination unit 104 projects from the camera body 101 when used, and is housed in the camera body 101 when not used.

  A focal plane shutter 113 (hereinafter referred to as a shutter) has a front curtain and a rear curtain composed of a plurality of light shielding blades. In this shutter 113, when not photographing, the aperture serving as a light passage opening is covered with the front curtain or the rear curtain to shield the photographing light flux, and during photographing, the front curtain and the rear curtain travel while forming slits. The light beam is passed to the image plane side.

Reference numeral 119 denotes a main switch for starting the camera. Reference numeral 120 denotes a release button that can be pressed in two stages. When the release button is pressed halfway, a shooting preparation operation (focus adjustment operation, photometry operation, etc.) is started, and when it is fully pressed, a shooting operation is started. Reference numeral 121 denotes a focus detection unit that detects a focus adjustment state by a phase difference detection method. The finder optical system and the focus detection unit 121 are disposed in regions facing each other across the optical axis (optical path) of the light beam from the imaging optical system 103 before being reflected by the half mirror 111.

  Reference numeral 123 denotes a finder mode changeover switch, and the setting of the optical finder mode (OVF mode) and the electronic finder mode (EVF mode) can be switched by operating the switch 123. Here, in the OVF mode, an object image can be observed through the finder optical system, and in the EVF mode, the object image can be observed through the display unit 107.

  An optical finder information display unit 180 displays predetermined information (for example, photographing information) on the focusing screen 105. Thereby, the photographer can observe the predetermined information together with the object image by looking into the eyepiece lens 109.

  In the above-described configuration, the half mirror 111 and the sub-mirror 122 are configured so that the first optical path state (first state) for guiding light to the finder optical system and the focus detection unit 121, the image sensor 106, and the focus detection, as will be described later. A second optical path state (second state) for guiding light to the unit 121 and a third optical path state (third state) for causing the image sensor 106 to directly receive light from the imaging optical system 103 ) Can be selectively taken.

  In the first optical path state, the half mirror 111 and the sub mirror 122 are obliquely arranged on the photographing optical path, and the light from the imaging optical system 103 is reflected by the half mirror 111 and guided to the finder optical system, The light transmitted through the half mirror 111 is reflected by the sub mirror 122 and guided to the focus detection unit 121. Thereby, in the first optical path state, the object image can be observed through the eyepiece lens 109 and the focus detection unit 121 can perform focus detection.

  In the second optical path state, only the half mirror 111 remains oblique on the photographing optical path, and the light from the imaging optical system 103 is reflected by the half mirror 111 and guided to the focus detection unit 121. In addition, the light transmitted through the half mirror 111 can reach the image sensor 106. Note that the sub mirror 122 is in a state of being retracted from the photographing optical path.

  As a result, in the second optical path state, a captured image can be displayed on the display unit 107 based on the output of the image sensor 106, or shooting (continuous shooting or movie shooting) can be performed, and the focus detection unit 121 can be used. Focus detection can be performed at.

  In the third optical path state, the half mirror 111 and the sub mirror 122 are retracted from the photographing optical path, and the light from the imaging optical system 103 can reach the image sensor 106 directly. As a result, in the third optical path state, a captured image can be displayed on the display unit 107 or photographed based on the output of the image sensor 106. This shooting can generate a high-definition image, and is suitable for enlarging the shot image and performing a large print.

  In order to switch the above-described three optical path states at high speed, the half mirror 111 is made of a transparent resin to reduce the weight. In addition, a polymer thin film having birefringence is attached to the back surface of the half mirror 111. For this reason, in the second optical path state, when a captured image is monitored by the display unit 107 or when high-speed continuous shooting is performed, a stronger low-pass is achieved in correspondence with the fact that all the pixels of the image sensor 106 are not used for imaging. Gives an effect.

  In addition, a fine pyramid-shaped periodic structure having a pitch smaller than the wavelength of visible light is formed on the surface of the half mirror 111 with a resin, and the refractive index difference between air and the resin is caused by acting as a so-called photonic crystal. It is also possible to reduce the light surface reflection due to the light and 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 including an electromagnetic motor and a gear train (not shown) changes the positions of the half mirror 111 and the sub mirror 122 to change the optical path state into the first optical path state, the second optical path state, and the third optical path state. Switch with.

  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 driving mechanism. High-speed continuous shooting can be performed. Further, the focus adjustment can be performed even when an image is displayed on the display unit 107.

  FIG. 7 is a block diagram showing an electrical configuration of the camera system according to the present embodiment. This camera system has an imaging system, an image processing system, a recording / reproducing system, and a control system. First, an explanation will be given regarding imaging and recording of an object 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 (control means) 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 light from an object on the imaging surface of the imaging element 106 via the imaging optical system 103, and an aperture (light quantity adjustment unit) 143 in the lens device 102, and if necessary. Thus, the traveling of the front curtain and rear curtain in the shutter 113 is adjusted, and an appropriate amount of object light is exposed to the image sensor 106.

  The imaging element 106 has 3700 square pixels arranged in the long side direction and 2800 in the short side direction, and has a total number of pixels of about 10 million, and each pixel has R (red) G (green) B A so-called Bayer array is formed in which (blue) color filters are alternately arranged to form a set of four pixels.

  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 image 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 and outputs, for example, a 10-bit digital signal according to the amplitude of the signal of each exposed pixel, and the subsequent image signal processing is executed by digital processing. The

  The image processing system is a signal processing system that obtains an image signal of a desired format from R, G, and B digital signals. The R, G, and B color signals are converted into luminance signals Y and color difference signals (R−Y), ( (B−Y) and the like.

  The RGB image processing circuit 131 is a signal processing circuit that processes an image signal of 3700 × 2800 pixels received from the image sensor 106 via the A / D converter 130, and is a white balance circuit, a gamma correction circuit, and an interpolation calculation high 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 memory (recording medium, not shown) and outputs an image signal to the display unit 107. The recording processing circuit 133 performs a writing process and a reading process of the image signal to the memory. The reproduction processing circuit 134 reproduces the image signal read from the memory 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 transformation, normalization, and Huffman encoding.

  The reproduction processing circuit 134 is a circuit that converts the luminance signal Y and the color difference signals RY and BY into a matrix signal, for example, an RGB signal. 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. With this configuration, an image captured by the camera can be monitored from a remote location.

  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, the 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 processing with the camera system control circuit 135 as a center.

  The AF control circuit 140 generates a focus detection signal by receiving a signal output from the focus detection sensor 167 corresponding to the focus detection area provided at a predetermined position on the imaging screen, and focuses the imaging optical system 103. The state (defocus amount) is detected.

  When the defocus amount is detected, the defocus amount is converted into a driving amount of a focusing lens which is a part of the imaging optical system 103 and transmitted to the lens system control circuit 141 via the camera system control circuit 135. To do.

  For a moving object, the focusing lens drive amount based on the result of predicting an appropriate lens stop position, taking into account the time lag from when the release button 120 is pressed to when the actual imaging operation starts. Instruct. Further, when it is determined that the brightness of the object is low and sufficient focus detection accuracy cannot be obtained based on the detection result of a brightness detection device (not shown) that is provided in the camera body 101 and detects the brightness of the object, An object is illuminated by a white LED or a fluorescent tube (not shown) provided in the illumination unit 104 or the camera body 101.

  When the lens system control circuit 141 receives the driving amount of the focusing lens sent from the camera system control circuit 135, the lens system control circuit 141 performs an operation such as moving the focusing lens in the direction of the optical axis L1 by a driving mechanism (not shown) in the lens device 102. And adjust the focus.

  When the AF control circuit 140 detects that the object 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 143 adjusts the amount of subject light directed toward the image plane in accordance with 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 a mount unit electrical contact (communication unit) 144a on the lens device 102 side and a mount unit electrical contact 144b on the camera body 101 side. Yes.

  1 to 5 are longitudinal sectional views of the camera system according to the present embodiment. A part of the lens device 102 is shown. In these drawings, operations of the driving mechanisms (mirror driving mechanisms) of the half mirror 111 and the sub mirror 122 are mainly shown in time series. The same members as those described in FIGS. 6 and 7 are denoted by the same reference numerals.

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

  In the figure, reference numeral 101 denotes a camera body, 102 denotes a lens device, 103a denotes a lens positioned closest to the image plane among a plurality of lenses constituting the imaging optical system, and 105 denotes a focusing screen of the finder optical system. Reference numeral 164 denotes a condenser lens that serves as a light beam capturing window in the focus detection unit 121, and 107 denotes a display unit. Reference numeral 163 denotes an eyepiece shutter (light-shielding member) that can advance and retract in the optical path of the finder optical system. This light-shielding member is a member that avoids an influence on imaging due to light from the eyepiece lens 109a side.

  The movable 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 movable together 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 the 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 (FIG. 3), the mirror stoppers (stopper members) 160 and 161 are in a 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 inclined 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 in which the rotation around the rotation axis 125 is suppressed.

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

  When the mirror stoppers 160 and 161 are retracted from the movement locus of the half mirror 111, or when the half mirror drive lever 170 is rotated clockwise in FIG. 3, the pin 173 is biased by a biasing force in the direction of arrow A by a torsion spring (not shown). Is in contact with the first cam surface 170b of the half mirror drive lever 170, and the pin 174 is in contact with the second cam surface 170c of the half mirror drive lever 170.

  Then, the pins 173 and 174 move along the first cam surface 170b and the second cam surface 170c in accordance with the rotation amount of the half mirror drive lever 170, respectively. 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 driving lever 170 and the half mirror supporting arm 171 via the pins 173 and 174 is operated, and the half mirror 111 is operated together with the half mirror receiving plate.

  1 to 5 are diagrams illustrating the operation of the half mirror 111 and the sub mirror 122. FIG. FIG. 1 shows the second optical path state described above, 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 described above.

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

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

  Next, a shooting sequence in the camera system of the present embodiment will be described with reference to FIG.

  In step S1, the process waits until the main switch 119 is operated (ON state), 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 S4. If the EVF mode is set, the process proceeds to step S5.

  In step S4, 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, an object can be observed together with the predetermined information via the eyepiece lens 109.

  In step S5, an image or predetermined information is displayed on the display unit 107. In this EVF mode, an object 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, an image (object image) is displayed on the display unit 107 by driving the imaging system and the image processing system.

  In step S6, the process waits until it is detected that the release button 120 is half-pressed on the basis of the output of the operation detection circuit 136, that is, until the SW1 is turned on, and the SW1 is turned on. Proceed to

  In step S7, subject luminance is measured (photometric operation), and the focus detection unit 121 performs a focus adjustment state detection operation (focus detection operation) using a phase difference detection method.

  These detection results are sent to the camera system control circuit 135, and an exposure value (shutter speed and aperture value) and a defocus amount are calculated. Based on the calculated defocus amount, the focusing lens of the imaging optical system 103 is driven under the control of the AF control circuit 140 and the lens system control circuit 141 to perform focusing. Further, the aperture 143 is driven based on the calculated aperture value to switch the opening area of the light passage opening.

  In step S8, 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 SW2 is in an ON state. Here, if SW2 is in the ON state, the process proceeds to step S9, and if it is in the OFF state, the process returns to step S6.

  In step S9, the half mirror 111 and the sub mirror 122 are set to the third optical path state (FIG. 5) by driving the mirror driving mechanism. In step S10, the image sensor 106 is exposed by operating the shutter 113 based on the previously calculated shutter speed, and in step S11, a high-definition image is captured by the image processing system.

  Note that the above-described shooting sequence is a case of shooting a high-definition image. When high-speed continuous shooting is performed, the sequence is partially different from the above-described sequence. That is, the half mirror 111 and the sub mirror 122 are in the second optical path state (FIG. 1), and the shutter 113 remains open.

  At this time, the light beam from the imaging optical system 103 is divided into a component reflected by the half mirror 111 to the focus detection unit 121 and a component transmitted through the half mirror 111. Then, the component that has passed through the half mirror 111 is received by the image sensor 106, and photographing is performed. When performing continuous shooting, the mirror drive mechanism is not driven, so that the half mirror 111 is held in the same state (the state shown in FIG. 1).

  The camera of the present embodiment detects a focus adjustment state by the phase difference detection method in the focus detection unit 121 even when the captured image is being monitored on the display unit 107, so that a high-speed focus adjustment operation ( Focusing lens focusing drive) can be performed.

  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, and when it is detected that the finder mode changeover switch 123 has been operated, the finder mode (OVF mode and EVF mode) is detected. The mode switching operation is immediately started (step S3 in FIG. 8).

  FIG. 9 is a flowchart for explaining the finder mode switching operation, which will be described below.

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

  First, a case where the OVF mode is switched to the EVF mode will be described.

  In the OVF mode, the optical path splitting system 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 object light is not guided to the optical viewfinder, first, in step S101, the camera system control circuit 135 closes the eyepiece shutter 163 by driving a drive source (not shown). That is, the eyepiece shutter 163 is caused to enter the finder optical path between the lens 109b and the lens 109c.

  This is to prevent the photographer from misunderstanding that the object image cannot be seen through the eyepiece lens 109 when the EVF mode is set. This is to prevent a ghost from being generated by being incident on 106.

  In step S102, the information display in the optical viewfinder is set to the non-display state by driving control of the information display unit 180 in the viewfinder. 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 battery consumption can be suppressed.

  In step S103, the sub-mirror 122 is retracted to the lower part of the mirror box in preparation for moving the half mirror 111 to the second optical path state (FIG. 1) by operating the mirror driving mechanism (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 half mirror drive lever 170 is rotated counterclockwise by the mirror drive mechanism. 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.

  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. With this configuration, the reflected light guided to the focus detection unit 121 by the sub mirror 122 (first optical path state), and the reflected light guided to the focus detection unit 121 by the half mirror 111 (second optical path state). Therefore, the position of the focus detection area can be hardly changed.

  Here, the focus position of the object image formed by imaging the light flux that has passed through the half mirror 111 on the image sensor 106 is slightly shifted from the focus position when the object light does not pass through the half mirror 111. Sometimes. For this reason, in step S106, the focus correction mode is activated to correct the shift of the focus position.

  In the first optical path state, the focus detection unit 121 causes the object image to be sharply formed on the image sensor 106 when the half mirror 111 and the sub mirror 122 are retracted from the imaging optical path (third optical path state). A focus detection signal is output.

  On the other hand, when the focus correction mode is on in the second optical path state, the focus detection unit transmits the half mirror 111 and projects the object image projected onto the image sensor 106 sharply. The focus detection signal 121 is corrected. As a result, when the focus correction mode is set in the second optical path state, the focusing position of the focusing lens in the second optical path state is the third amount corresponding to the correction of the focus detection signal of the focus detection unit 121. It shifts with respect to the focusing position of the focusing lens in the optical path state.

  Accordingly, when the EVF mode is set, the release button 120 is fully pressed to start the imaging operation, and when the second optical path state is switched to the third optical path state, the shutter 113 is synchronized with this. The front curtain drive mechanism is charged (shutter 113 is closed), and the focusing lens is returned to the original position (the in-focus position in the third optical path state) as much as the focus position of the object image is corrected by the focus correction mode. Thereafter, the shutter 113 is opened for a predetermined time, and imaging by the imaging element 106 is performed.

  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 S <b> 107, only the front curtain of the shutter 113 is caused to travel so as to be in a bulb exposure state, and object light is continuously guided to the image sensor 116, thereby enabling imaging for displaying an image on the display unit 107. In step S108, the display unit 107 is powered on.

  In step S109, object images are continuously picked up by the image pickup device 106, real-time display is started on the display unit 107, and a series of viewfinder switching processes is returned.

  In the EVF mode (second optical path state), since the object light emitted from the imaging optical system 103 is refracted by the half mirror 111, the electronic image of the object displayed on the display unit 107 in real time is 3 is slightly shifted in the vertical direction as compared with the actually captured image in the optical path state 3.

  FIG. 12 is a diagram for explaining a difference between an image displayed on the display unit 107 in the second optical path state and an image actually captured in the third optical path state.

  In the figure, reference numeral 190 denotes an imaging range (region surrounded by a thick frame) that is imaged in the second optical path state, that is, a range of a captured image that can be output to the display unit 107 during real-time display. Reference numeral 191 denotes an imaging range in which imaging is performed in the third optical path state.

  The imaging range 190 and the imaging range 191 are shifted in the up-down direction. As a result, the imaging range 190 of the imaging range 190 that can be output to the display unit 107 but is not imaged in the third optical path state, that is, the imaging range 190. There is a region that does not overlap with 191.

  Therefore, the reproduction processing circuit 134 performs processing so that the area 192 corresponding to the area 190a in FIG. 12 is not displayed and the entire photographing range 190 is not displayed on the display unit 107 as shown in FIG. As a result, the display unit 107 displays a region (corresponding to a part of the claims) of the imaging region 190 looking into the region 192. By doing so, it is possible to eliminate the problem that the image is not actually shot despite being displayed on the display unit 107 in the EVF mode.

  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 dividing system composed of the half mirror 111 and the sub mirror 122 is in the second optical path state (FIG. 1), and real-time 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 imaging 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 shooting.

  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 clockwise in FIG. 1 to move the half mirror 111 and the sub mirror 122, which are optical path dividing systems, from the state of FIG. 2 to the state of FIG. 3 to the state of FIG. To be in the state (third optical path state).

  When the half mirror drive lever 170 rotates 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, and the position of the half mirror 111 is switched. The mechanical reliability of (switching between OVF mode and EVF mode) can be increased.

  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 111 is rotated from the third optical path state (FIG. 5) to the first optical path state (FIG. 3) by rotating the half mirror drive lever 170 counterclockwise in FIG. ). At this time, the half mirror 111 receives a biasing force of a spring (not shown) in the mirror driving mechanism and is in contact with the mirror stoppers 160 and 161.

  In step S117, the eyepiece shutter 163 is opened.

  In step S118, it is determined whether or not the manual (M) focus mode is set based on the output from the operation detection circuit 136. If the manual focus mode is set, the process proceeds to step S107. If the mode is selected, the process proceeds to step 120.

  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 in the electronic image display than in the optical viewfinder. The process proceeds to step S107.

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

  In step S121, predetermined information is lit and displayed in the finder by drive control of the information display unit 180 in the optical finder, and a series of finder switching processes are terminated.

  Next, the focus detection unit 121 and signal processing for focus detection will be described.

  1 to 5, reference numeral 164 denotes a condenser lens, 165 denotes a reflecting mirror, 166 denotes a re-imaging lens, and 167 denotes a focus detection sensor.

  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) is incident on the condenser lens 164 below the mirror box. Thereafter, the light is deflected by the reflection mirror 165, and a secondary image of the object is formed on the focus detection sensor 167 by the action of the re-imaging lens 166.

  The focus detection sensor 167 includes at least two pixel columns, and an image of an object image formed by the imaging optical system 103 on the focus detection region is formed between the output signal waveforms of the two pixel columns. Depending on the state, a relatively laterally shifted state is observed. The shift direction of the output signal waveform is reversed at the front and rear pins, and the focus detection (contrast detection method) detects this phase difference (shift amount) including the shift direction using a method such as correlation calculation. Is the principle.

  10 and 11 are diagrams showing output signal waveforms of the focus detection sensor 167 input to the AF control circuit 140. FIG. The horizontal axis represents the pixel arrangement, and the vertical axis represents the output value. FIG. 10 shows an output signal waveform when the object image is out of focus, and FIG. 11 shows an output signal waveform when the object image is in focus.

  In general, the light beam for focus detection is not the same as the imaging light beam with the aperture opened, and focus detection is performed using a part of the imaging light beam. That is, a dark F-number light beam is used for focus detection. Further, in consideration of mechanism errors, the position of the image sensor 106 and the position of the focus detection sensor 167 are not optically conjugate in a strict sense. As a result, even if the object image is in focus, a slight initial phase difference Δ remains between the two output signal waveforms (FIG. 11).

  This is different from the correction in the focus correction mode for sharpening the electronic image display focus described above (step S106 in FIG. 9). The existence of the initial phase difference Δ is not usually a problem because the true phase difference can be known by subtracting this from the phase difference detected by the correlation calculation of the two images.

  However, there is a problem that the position of the reflecting surface of the sub-mirror 122 in the first optical path state and the position of the reflecting surface of the half mirror 111 in the second optical path state do not completely match in terms of mechanism accuracy, and the initial phase difference Δ is also slightly Come different. With normal part processing accuracy, there is a possibility that the reflective surface is displaced in the normal direction by about 30 μm. If this amount is reduced, the cost for processing the part becomes extremely high.

  Therefore, the initial phase difference Δ is set for each of the first optical path state and the second optical path state, and the value of the initial phase difference Δ is changed according to the optical path state. For example, the initial phase difference Δ in the first optical path state and the second optical path state is stored in a memory 135 a provided in the camera system control circuit 135. Then, the initial phase difference in the first optical path state or the second optical path state is detected by detecting the position of the mirror (half mirror 111 and sub mirror 122) or detecting the finder mode (EVF mode and OVF mode). Δ can be read out.

  With this configuration, focus detection can be performed with good accuracy in any optical path state.

  In this way, first, using the idea of the initial phase difference, it is possible to detect the in-focus state by determining the identity of a set of signals. Further, the defocus amount can be obtained by detecting the phase difference using a known method using correlation calculation, for example, the method disclosed in Patent Document 5 described above. If the obtained defocus amount is converted into an amount by which the focusing lens of the imaging optical system 103 should be driven, automatic focus adjustment is possible.

  In this method, since the amount of the focusing lens to be driven is known in advance, the focusing lens is normally driven only once to the in-focus position, and extremely fast focus adjustment is possible.

  According to the camera of the present embodiment, when the electronic image of the object image is displayed on the display unit 107 in the second optical path state, the focus detection unit 107 uses the phase difference detection method similarly to the first optical path state. The focus adjustment state can be detected, and high-speed focus adjustment operation (focusing driving of the focusing lens) can be performed. Further, by performing continuous shooting or moving image shooting in the second optical path state, high-speed focus adjustment operation is possible. In addition, as compared with the case where the focus detection unit is provided in each of the lens device and the camera body as in Patent Document 4 described above, it is possible to reduce the size of the camera and to prevent an increase in cost.

  In this embodiment, in the second optical path state (FIG. 1), the emitted light from the imaging optical system 103 is guided to the focus detection unit 121 by the half mirror 111, and the focus detection unit 121 performs focus adjustment by the phase difference detection method. In addition to this, in addition to this, the image sensor 106 may perform focus adjustment by a contrast detection method using light transmitted through the half mirror 111.

  For example, first, the focusing lens can be moved to the vicinity of the in-focus position by focus adjustment by the phase difference detection method, and the focusing lens can be stopped at the in-focus position by focus adjustment by the contrast detection method. Thereby, the focusing lens can be moved quickly to the vicinity of the in-focus position, and the accuracy of the in-focus position can be increased.

  In this embodiment, the camera system including the lens device 102 and the camera main body 101 has been described. However, the present invention can also be applied to a camera in which the lens device and the camera main body are integrated. In this case, the lens system control circuit 141 in FIG. 7 becomes unnecessary, and the control operation of the lens system control circuit 141 is performed by the camera system control circuit 135.

  As described above, a plurality of lens devices 102 having different focal lengths can be attached to and detached from the camera body 101. Therefore, a signal transmitted from the camera system control circuit 135 is sent to the mounted lens apparatus 102 depending on whether it is the camera body 101 as described in the present embodiment or a conventional camera body. Different.

  That is, when the camera body 101 is mounted as described in the present embodiment, the following communication is performed between the camera system control circuit 135 and the lens system control circuit 141.

  The lens system control circuit 141 that has received a signal indicating the second optical path state (second mode) from the camera system control circuit 135 controls the aperture opening of the aperture 143. This is because when the conventional camera body is used, the aperture is narrowed down for photometry and photographing, whereas when the camera body 101 in this embodiment is used, the display unit (image display unit) 107 is used. This is because the exposure amount is adjusted in order to display an image on top. In addition, when the conventional camera body is used, or in the camera system of this embodiment, the lens control circuit 141 sends a signal indicating the first optical path state (first mode) from the camera system control circuit 135. Automatic focus adjustment when received is performed with the aperture fully open.

  On the other hand, in the camera system of this embodiment, even when the diaphragm 143 is being narrowed down in the second optical path state, the focus adjustment in the imaging optical system 103 based on the detection result in the focus detection unit 121 is permitted. . In the camera system of the present embodiment, the aperture opening of the aperture 143 is imaged on the display unit 107 after shooting with the aperture opening changed in the second optical path state (for example, continuous shooting or moving image shooting). Return to the state for displaying.

  According to this embodiment, when the light beam from the imaging optical system 103 is guided to the finder optical system (first optical path state) or when guided to the image sensor (second optical path state), the light beam is focused on both. It is also guided to the detection unit 121. Thereby, not only when observing an object image through the finder optical system, but also when capturing an object image with an image sensor (for example, when performing continuous shooting or moving image shooting), the focus detection unit 121. The focus adjustment state can be detected by the phase difference detection method.

  For this reason, when an image is picked up by the image sensor 106, the focus adjustment operation can be performed more quickly than when the focus adjustment state is detected by the contrast detection method (conventional). Moreover, since it is not necessary to provide two focus detection units as in Patent Document 4 described above, it is possible to prevent an increase in the size and cost of the apparatus.

  Further, even when an image captured by the image sensor 106 is displayed on the display unit 107 and this image is observed, the focus adjustment operation can be performed quickly as described above.

  A camera system that is Embodiment 2 of the present invention will be described.

  In the first embodiment, the first optical path state is directly shifted to the second optical path state, and the third optical path state is passed when the second optical path state is shifted to the first optical path state. I am doing so.

  On the other hand, in the present embodiment, when switching between the first optical path state and the second optical path state, the third optical path state is passed, which is different from the first embodiment. Hereinafter, a different part from Example 1 is demonstrated.

  The configuration of the camera other than the split optical system (half mirror, sub mirror, and mirror driving mechanism) is substantially the same as the configuration of the camera in the first embodiment, and the same members as those described in the first embodiment are used. The same code is used.

  FIG. 14 is a diagram for explaining the operation of the split optical system in the present embodiment. In the figure, (A) is a first optical path state, (C) is a third optical path state, and (E) is a second optical path state. (B) is a diagram in which the transition process from the first optical path state to the third optical path state is overwritten. (D) is a diagram in which the transition process from the third optical path state to the second optical path state is overwritten. FIG.

  In these drawings, L2 is an optical axis of the imaging optical system 103, 206 is an image sensor (light receiving surface), 211 is a movable half mirror, 222 is a sub mirror, and 201 is a light shielding plate. Reference numeral 202 denotes a mirror stopper, which holds the half mirror 211 in the first optical path state by contacting the half mirror 211. Reference numeral 203 denotes a mirror stopper, which holds the half mirror 211 in the second optical path state by contacting the half mirror 211. Unlike the first embodiment, these mirror stoppers 202 and 203 are fixed in the camera body.

  In the first optical path state shown in FIG. 14A, the half mirror 211 is obliquely arranged on the optical axis L2, and is positioned by abutting against the mirror stopper 202 by receiving a biasing force of a spring (not shown). Yes. Further, a sub mirror 222 is located behind the half mirror 211.

  This first optical path state is a state when the camera is set to the OVF mode as in the first embodiment, and an object image can be observed through the finder optical system, and in the focus detection unit 121. The focus adjustment state can be detected by the phase difference detection method.

  A part of the light beam incident on the half mirror 211 from the imaging optical system 103 located on the left side in the drawing along the optical axis L2 is reflected on the surface of the half mirror 211 to the upper side of the camera (upward in the drawing). Led to. Further, the remaining light beam is transmitted through the half mirror 211, reflected by the sub mirror 222 located behind the half mirror 211 to the lower side of the camera (downward in the figure), and guided to the focus detection unit 121.

  In the third optical path state shown in FIG. 14C, the half mirror 211 and the sub mirror 222 are retracted to a position above the camera that does not block the imaging light flux. At this time, the light shielding plate 201 covers a region of the half mirror 211 that does not overlap the sub mirror 222, and shields the reverse incident light from the finder optical system together with the sub mirror 222. Thereby, it is possible to prevent reverse incident light from the finder optical system from entering the image sensor 206 and to prevent a ghost from occurring.

  In the second optical path state shown in FIG. 14 (E), the half mirror 211 is obliquely arranged on the optical axis L2, and is positioned by abutting against the mirror stopper 203 under the biasing force of a spring (not shown). Yes. On the other hand, the sub mirror 222 is located above the camera together with the light shielding plate 201 and is retracted from the photographing optical path.

  This second optical path state is a state when the camera is set to the EVF mode as in the first embodiment, and an object image can be observed through the display unit 107 and also in the focus detection unit 121. The focus adjustment state can be detected by the phase difference detection method.

  A part of the light beam incident on the half mirror 211 from the imaging optical system 103 located on the left side in the drawing along the optical axis L2 is reflected to the lower side of the camera by the back surface of the half mirror 211 and guided to the focus detection unit 121. Further, the remaining light flux passes through the half mirror 211 and enters the image sensor 206.

  The transition operation from the first optical path state (A) to the third optical path state (C) is almost the same as the mirror up operation of a general single-lens reflex camera as shown in FIG. That is, the half mirror 211 rotates so that the surface faces upward of the camera, and the sub mirror 222 rotates so that the reflection surface faces upward of the camera. At this time, the sub mirror 222 moves to a position along the half mirror 211.

  Note that the transition operation from the third optical path state (C) to the first optical path state (A) is the reverse of the above-described operation. In addition, the operations of the half mirror 211 and the sub mirror 222 described above are performed by, for example, transmitting the driving force of the motor to the cam via the gear train and rotating the cam, thereby causing the half mirror 211 and the sub mirror 222 engaged with the cam to rotate. This can be done by moving the pin.

  On the other hand, in the transition operation from the third optical path state (C) to the second optical path state (E), the half mirror 211 disposed substantially parallel to the optical axis L2 is the rear end of the half mirror 211, that is, imaging. It starts to fall from the side close to the element 206 and comes into contact with the mirror stopper 203. At this time, the back surface of the half mirror 211 faces the imaging optical system 103 side.

  The position of the half mirror 211 substantially coincides with the position of the sub mirror 222 in the first optical path state. Here, in the present embodiment, unlike the first embodiment, the reflecting surface of the half mirror 211 is positioned on the image sensor 206 side, so that the optical axis after deflection by the half mirror 211 is the focal point in the first optical path state. The position of the half mirror 211 is determined so as to coincide with the optical axis incident on the detection unit 121.

  With this configuration, the position of the focus detection region can be hardly changed between the first optical path state and the second optical path state.

  In this embodiment, when switching between the first optical path state and the second optical path state, the states shown in FIGS. 14B to 14D are passed, so that the mirror stoppers 202 and 203 are connected to those in the first embodiment. Thus, it is not necessary to be movable (structure that advances and retreats with respect to the movement locus of the mirror). Further, since the operations of the half mirror 211 and the sub mirror 222 are not hindered by the mirror stoppers 202 and 203, it is possible to ensure mechanical reliability when switching between the first optical path state and the second optical path state. Can do.

  According to the camera of the present embodiment, even when the electronic image of the object image is displayed on the display unit 107 in the second optical path state, the focus adjustment state is detected by the phase difference detection method as in the first optical path state. Therefore, high-speed focus adjustment operation (focusing lens focusing drive) can be performed. Further, by performing continuous shooting or moving image shooting in the second optical path state, high-speed focus adjustment operation is possible. In addition, since it is not necessary to provide the focus detection unit in each of the lens device and the camera body as in the above-mentioned document 4, the camera can be reduced in size and the cost is not increased.

  In the first and second embodiments, a camera that obtains a color image has been described as an example. However, the present invention is not limited to this, and the present invention is not limited to this. For example, an infrared imaging device, a monochrome camera, and a binocular equipped with an imaging function. Needless to say, this is applicable.

It is a longitudinal cross-sectional view of a camera system. It is a longitudinal cross-sectional view of a camera system. It is a longitudinal cross-sectional view of a camera system. It is a longitudinal cross-sectional view of a camera system. It is a longitudinal cross-sectional view of a camera system. It is a figure which shows schematic structure of a camera system. It is a block diagram which shows the electric constitution of a camera system. It is a flowchart for demonstrating the imaging | photography sequence of a camera system. It is a flowchart for demonstrating switching operation | movement of finder mode. It is a figure showing the waveform of the output signal of the sensor for focus detection. It is a figure showing the waveform of the output signal of the sensor for focus detection. It is a figure showing the relationship between the visual field which can be output to the electronic image display of real-time display, and the visual field imaged. It is a figure showing the relationship between the visual field which can be output to the electronic image display of real-time display, and the visual field imaged. It is a figure for demonstrating the operation | movement of the optical path splitting system in Example 2 (AE).

Explanation of symbols

103: Imaging optical system 106: Imaging elements 109a to 109c: Lens 111: Half mirror 121: Focus detection unit 122: Sub mirror

Claims (3)

An image sensor that photoelectrically converts an object image formed by a light beam from a photographing lens;
A focus detection unit that detects a focus adjustment state of the photographic lens by a phase difference detection method in which a light beam from the photographic lens is guided ;
A finder optical system for guiding a light beam from the photographing lens;
A first mirror that reflects a portion of the light flux from the photographic lens and transmits the remainder ;
Image display means for displaying image data acquired using the output from the image sensor ;
The first mirror guides the light beam reflected by the first mirror to the finder optical system and guides the light beam transmitted through the first mirror to the focus detection unit; and Switching to a second state in which the light beam reflected by the mirror is guided to the focus detection unit and the light beam transmitted through the first mirror is guided to the image sensor;
An image pickup apparatus , wherein the image display means displays image data acquired using an output from the image pickup device when the first mirror is in the second state. The finder optical system and the focus detection unit are disposed in regions facing each other across an optical path of a light beam from the photographing lens before being reflected by the first mirror. Item 2. The imaging device according to Item 1. The imaging apparatus includes a second mirror that is driven in accordance with the switching operation of the first mirror,
The second mirror is disposed at a position for guiding the light beam transmitted through the first mirror in the first state to the focus detection unit, and the light beam transmitted through the first mirror in the second state. the imaging apparatus according to claim 1 or 2, characterized in that it is arranged at a position not obstructed.