JP2006197406A - Image pickup device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To pick up an object image (live view) while observing the object view through a finder and to obtain the AF area of a wide visual field. <P>SOLUTION: A main mirror 106 is fixed and is, for example, a half mirror such as a pellicle mirror. A luminous flux transmitting a photographic lens 202 from an object is divided into reflected light and transmitting light, the reflected light is made incident on an AF sensor unit 110 and the transmitting light is made incident on an imager 122 constituted of imaging devices such as a CCD. The image (live view) obtained by being photoelectrically converted by the imager 122 is displayed on an EVF (electronic viewfinder) display unit 124, enlarged by a loupe lens 126 and picked up while being observed through the finder. The luminous flux of a full screen range is reflected by the main mirror 106, and the full screen area becomes the object of an AF area. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an imaging apparatus that performs digital photography while observing a subject image with a viewfinder.

  An imaging device such as a digital camera, a digital video camera (including news reports and movies), a microscope, an endoscope, and the like has a finder and images are taken while observing a subject with the finder. For example, in a digital single-lens reflex camera (hereinafter referred to as “camera” where appropriate), generally, a light beam from a subject is reflected by a main mirror called a quick litter mirror, and reflected light is guided to an optical viewfinder. The captured subject image (live view) is observed with an optical finder, and at the time of photographing, the main mirror is flipped up to guide the light beam from the subject to an image sensor (imager) such as a CCD.

  However, in the flip-up type main mirror (quick litter mirror), the release time lag tends to be longer by the time corresponding to the operation time of the main mirror because the main mirror is repeatedly raised and returned to the initial position for each shooting. It is in.

Therefore, in Japanese Patent Application Laid-Open No. 2002-182268, a main mirror is fixed as a semi-transmissive mirror (half mirror), and a light beam from an object is divided into a reflected light and a transmitted light by the main mirror, and the reflected light is reflected. Has been proposed in which the transmitted light is guided to an image pickup device (imager) such as a CCD and a photoelectrically converted image is observed as a live view. In this configuration, since the main mirror is fixed, there is no release time lag due to the operation time of the main mirror.
JP 2002-182268 A

  However, in the configuration of the above-mentioned Japanese Patent Application Laid-Open No. 2002-182268, it is desired to reduce the reflected light as much as possible in order to minimize the reduction in the amount of light to the image sensor, but the reflection is performed so as to ensure the brightness of the observation image on the optical viewfinder. It is necessary to increase the light as much as possible, and it is difficult to set the reflectivity of the main mirror. In general, in order to ensure the sensitivity on the imaging side, the finder side must be sacrificed as a result.

Further, when the TTL phase difference type AF sensor is used for distance measurement, the AF mirror can be rotated, and the AF mirror is rotated to the retracted position at the time of photographing. Therefore, the release time lag is increased by the rotation time of the AF mirror. .
Furthermore, if the AF mirror becomes larger, the AF area can be set wider. However, if the AF mirror is made larger, the space for securing the rotation of the AF mirror becomes wider, and the size of the AF mirror is restricted due to the space relationship, and an AF area with a wide field of view cannot be obtained.

  An image pickup apparatus according to the present invention is an image pickup apparatus having a finder, is fixed in a camera body, has a reflection surface, and reflects a light beam that has passed through a photographing lens by the transmitted light transmitted through the reflection surface and the reflection surface. Provided in the finder; an optical path dividing means for dividing the reflected light; an imaging means for receiving transmitted light from the optical path dividing means; a focus detecting means for receiving reflected light from substantially the entire reflecting surface; Imaging display means for displaying an image from the imaging means.

  According to the present invention, since the image of the imaging unit that receives the transmitted light from the fixed optical path dividing unit is displayed on the imaging display unit in the finder, the live view can be imaged while observing with the finder, and the entire screen is displayed. Since the light flux in the range is reflected by the fixed optical path dividing means, the entire screen range becomes the target of the AF area, and a wide-field AF area is obtained.

  In the present invention, a light beam from a subject is split into transmitted light and reflected light by a fixed pellicle mirror, and the transmitted light is received by an image sensor such as a CCD having an electronic shutter function, and an image on the image sensor is displayed on a liquid crystal display ( LED) is displayed on an EVF display unit, and is magnified and observed with a magnifying glass.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic longitudinal sectional view of an imaging apparatus according to an embodiment of the present invention embodied as a digital single-lens reflex camera.
As shown in FIG. 1, a camera (digital single-lens reflex camera) 10 has a camera body 100 having a mirror box unit 102 and a photographing lens 202 as a photographing optical system, and a lens mount 200a is attached to the body mount 100a. And a lens unit (so-called interchangeable lens) 200 that is detachably attached to the body.

  A system controller 104 composed of a CPU or the like is provided in the camera body 100 and controls the movement of each component of the camera body. The lens unit 200 is also provided with a system controller (not shown), and the system controller 104 of the camera body and the system controller of the lens unit are electrically connected to each other by the communication means (not shown) of the camera body and the lens unit. Have been replaced. For example, subject distance information output from an AF sensor unit, which will be described later, is input to the system controller 104 and transmitted to the system controller of the lens unit 200 via the communication means of the camera body and lens unit, and lens driving means (not shown). Is driven to focus the taking lens 212.

  A main mirror 106 is fixedly housed in the mirror box unit 102 of the camera body, and the main mirror is a half mirror such as a pellicle mirror. Since the main mirror is a half mirror, the light path from the subject that has passed through the photographing lens 202 is divided into reflected light and transmitted light, and as will be described later, the reflected light path passes through the AF light path and the transmitted light. The optical path is a finder optical path. If the main mirror 106 functioning as the optical path dividing means is thin like a pellicle mirror, the occurrence of optical aberration is suppressed.

An AF sensor unit 110 is disposed above the mirror box unit 102, and behind the mirror box unit 102 (on the opposite side to the subject) is a mechanical shutter, for example, a focal plane shutter 120, and an image sensor such as a CCD. An imager (imaging means) 122 is arranged. An imager 122 having an electronic shutter function is used.
Since the main mirror 106 is fixed and the main mirror is not movable, the focal plane shutter 120 can be opened prior to the shutter release, and by combining the electronic shutter of the imager 122 with the focal plane shutter (mechanical shutter). The release time lag is greatly shortened.

  The reflected light from the main mirror 106 is incident on the AF sensor unit 110, and distance measurement and focusing are performed using the reflected light. The transmitted light from the main mirror 106 is incident on the imager 122 via the focal plane shutter 120, and an image (live view) obtained by photoelectric conversion is displayed on the EVF display element 124 and magnified by the loupe lens 126. To be observed.

  A rear display unit 128 may be provided in the camera body 100 to display a reproduced image, and an image (live view) of the imager 122 may be displayed on both the EVF display element 124 and the rear display unit 128. In this configuration, as the electronic viewfinder (electronic viewfinder; EVF), two series, that is, a series through the loupe lens 126 and a series by the rear display unit 128 can be used, and it is possible to respond to various requests of users. For example, each of the EVF display element 124 and the rear display unit 128 includes a liquid crystal display (LED).

The rear display unit 128 is normally fixed to the rear surface of the camera body 100, but the rear display unit may be movable so that self-photographing can be performed while observing a live view of the rear display unit.
Since the finder is an electronic finder (EVF), even when the reflectivity of the main mirror 106 is low and the amount of reflected light is small, insufficient light quantity of the finder can be easily controlled and corrected, and a bright finder can be obtained. Therefore, there is no difficulty in setting the reflectance of the main mirror 106.

  The AF sensor unit 110 performs focus detection by, for example, a phase difference detection method, and includes a condenser lens 112, a diaphragm 114, a pair of separator lenses 116, and a distance measuring element (AF sensor) 118. Although the phase difference detection AF sensor unit 110 is well known and will not be described in detail, the reflected light from the main mirror 106 is collected by a condenser lens 112, enters a separator lens 116 through a diaphragm 114, and enters two light beams. And is received by the distance measuring element 118. Then, the deviation amount of the light quantity distribution of the two light beams in the distance measuring element 118 is output to the system controller 104, the subject distance is calculated by the system controller, and the subject distance information is transmitted to the system controller (not shown) on the lens unit side. Then, the lens driving means (not shown) is driven to focus the photographing lens 212.

  In AF with an image sensor, the AF speed is slow because the position of the contrast peak is determined by driving the photographic lens, and the AF speed is slow. On the other hand, in the AF sensor unit of the phase difference detection method, the subject distance is calculated before shooting. Since the lens is driven, the AF speed is fast and focusing is performed quickly.

  Since the main mirror 106 functions as an AF mirror and the AF mirror is unnecessary, there is no room for a release time lag due to the rotation of the AF mirror. In addition, since the light flux in the entire screen range is reflected by the main mirror and is incident on the AF sensor unit 110, the entire screen range becomes the target of the AF area, and a wide-field AF area is obtained.

  FIG. 2 shows a flowchart of the digital photographing operation under live view observation. First, the power switch (not shown) is turned on to start (S101). When the power switch is turned on, the camera is activated, the focal plane shutter (shutter) 120 is opened (S102), and the imager 122 receives light and undergoes photoelectric conversion. The displayed image is displayed on one or both of the EVF display unit 124 and the rear display unit 128, and a live view is observed (S103).

The first release of the shutter 120 is monitored (S103), and when the first release is performed, the distance is measured by the reflected light from the main mirror 106 incident on the AF sensor unit 110 (S105), and the photographing lens 202 is driven to perform the focusing. A burn is made (S106). Next, the 2nd release of the shutter 120 is monitored (S107). When the 2nd release is performed, the incident light beam is narrowed down by the diaphragm (S108), and controlled by the system controller 104 to operate the electronic shutter function of the imager 122 to perform exposure. Is made (S109).
In S014 and S107, if the shutter 120 is not released 1st or 2nd, it waits until it is released.

  When the exposure by the electronic shutter is completed, the aperture is opened (S110), the captured image data is read (S111), A / D converted, and stored in the memory through image processing such as compression processing (S113). Then, the power switch is monitored to be turned off (S114). If the power switch is not pushed and remains on, the process returns to S104, and imaging is repeated. If the power switch is pushed and turned off, power supply to the rear display unit 128 is stopped. Then, the live view is ended (S115), the shutter 120 is closed (S116), the camera enters a so-called sleep state, and the photographing operation is ended (S117).

  As described above, according to the present invention, since the image of the imager 122 that receives the transmitted light from the fixed main mirror 106 is displayed on the EVF display unit 124 in the finder, the live view is displayed in the finder (electronic finder). ) Can be taken while observing. Further, since the light flux in the entire screen range is reflected by the fixed main mirror 106, the entire screen range becomes the target of the AF area, and an AF area with a wide field of view is obtained.

  The embodiments described above are for explaining the present invention, and the present invention is not limited to the embodiments. Modifications and applications other than the above can be made without departing from the gist of the present invention. Needless to say.

  According to the present invention, a live view can be photographed while being observed with an electronic viewfinder (EVF), and the present invention can be widely applied to the field of digital photographing requiring AF with a wide field of view.

1 shows a schematic longitudinal sectional view of an imaging apparatus according to an embodiment of the present invention embodied as a digital single-lens reflex camera. 3 shows a flowchart of a photographing operation in the embodiment.

Explanation of symbols

10 Imaging device (digital single-lens reflex camera)
100 camera body 104 system controller 106 main mirror (light path dividing means)
110 AF sensor unit (focus detection means)
120 focal plane shutter (mechanical shutter)
122 imager (imaging means)
124 EVF display unit (imaging display means)
126 Loupe lens 128 Rear display unit 200 Lens unit 212 Shooting lens

Claims (5)

In a camera with a viewfinder,
An optical path splitting unit that is fixed in the camera body, has a reflecting surface, and splits the light beam that has passed through the photographing lens into transmitted light that has passed through the reflecting surface and reflected light that has been reflected by the reflecting surface;
Imaging means for receiving transmitted light from the optical path dividing means;
Focus detection means for receiving reflected light from substantially the entire reflective surface;
An imaging display means provided in the finder and displaying an image from the imaging means;
A camera characterized by comprising The imaging apparatus according to claim 1, wherein the focus detection unit is a phase difference detection type focus detection unit. The imaging apparatus according to claim 2, wherein the focus detection unit is a focus detection unit capable of measuring multiple points of a subject. 4. The imaging apparatus according to claim 1, wherein the optical path dividing means is a pellicle mirror. 5. The image pickup apparatus according to claim 1, wherein the image pickup unit has an electronic shutter function, and a mechanical shutter is provided in front of the image pickup unit.

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