Imaging device

Provided is an imaging device including a lens mounting portion, which is a portion on which or from which an interchangeable lens is mountable or removable, an imaging element, and an optical system provided in a light path between the interchangeable lens and the imaging element in a state in which the interchangeable lens is mounted on the lens mounting portion. The optical system is disposed at a first position at which an image of a light flux from the optical system is formed on the imaging element at a position in the light path between the interchangeable lens and the imaging element, and is moved to a second position, which is different from the first position from the first position in association with an operation of removing the interchangeable lens from the lens mounting portion.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to an imaging device.

Background Art

Imaging devices such as lens interchangeable digital cameras have been proposed. In order to miniaturize these imaging devices, it is conceivable that imaging elements such as a CCD and a CMOS be miniaturized. However, if imaging is performed by an interchangeable lens made for an imaging element size, which has been widely used in a video camera, being mounted on a camera main body, only some of rays of light from the interchangeable lens are received by an imaging element, and thus an angle of view is narrowed. Therefore, in order to increase an angle of view, an imaging device including a converter lens inside a camera main body has been proposed. In addition, an imaging device including a converter lens has a widened angle of view, and an F-number of the entire optical system including an interchangeable lens and the converter lens is decreased, and thus imaging can be performed with high brightness. Therefore, an ISO sensitivity can be minimized in the imaging device even under a dark imaging environment and imaging with less noise can be performed. Patent Document 1 discloses a digital camera in which a converter lens which is an optical system provided between an interchangeable lens and an imaging element is driven by an electric motor depending on the type of interchangeable lens.

CITATION LIST

Patent Literature

However, in an imaging device including a converter lens, there is a problem that an imaging element may be burned due to sunlight condensing on the imaging element in a case where an interchangeable lens is removed from a camera main body, or the like. Since the digital camera disclosed in Patent Document 1 drives the converter lens using electric power of the electric motor, it is difficult to prevent the imaging element from being burned during non-electrification of the imaging device such as a case where the interchangeable lens is removed from the camera main body. An object of the present invention is to provide an imaging device capable of preventing an imaging element from being burned due to a light flux through an optical system provided between an interchangeable lens and the imaging element even when the interchangeable lens is removed from a camera main body.

SUMMARY OF THE INVENTION

According to an embodiment of the present invention, there is provided an imaging device including a lens mounting portion, which is a portion on which or from which an interchangeable lens is mountable or removable, an imaging element, and an optical system provided in a light path between the interchangeable lens and the imaging element in a state in which the interchangeable lens is mounted on the lens mounting portion, in which the optical system is disposed at a first position at which an image of a light flux from the optical system is formed on the imaging element at a position in the light path between the interchangeable lens and the imaging element, and is moved to a second position, which is different from the first position, from the first position in association with an operation of removing the interchangeable lens from the lens mounting portion.

According to an imaging device of the present invention, it is possible to prevent an imaging element from being burned due to a light flux through an optical system provided between an interchangeable lens and the imaging element even when the interchangeable lens is removed from a camera main body.

DESCRIPTION OF THE EMBODIMENTS

FIGS. 1A and 1Bare perspective views illustrating the appearance of an imaging device of the present embodiment.

FIG. 1Aillustrates a state where an imaging device1is viewed from a subject side on a side thereabove.FIG. 1Billustrates a state where the imaging device1is viewed from a photographer side on a side thereabove. In addition,FIG. 2is a perspective view illustrating the appearance of the imaging device in a state in which an interchangeable lens is removed.

The imaging device1is a lens interchangeable digital video camera. As illustrated inFIGS. 1 and 2, the imaging device1includes an interchangeable lens2of a bayonet system and a lens mounting portion101corresponding to a bayonet system. The lens mounting portion101is a portion on which and from which the interchangeable lens2is mountable and removable. The interchangeable lens2rotates centering on the optical axis when mounted on or removed from the lens mounting portion101.

The lens mounting portion101is fixed to a lens mounting fixing member201disposed inside the imaging device1. In addition, a converter lens102(FIG. 2) as an optical system is provided between the lens mounting portion101and an imaging element110(FIG. 3) to be described later and on an optical axis149connecting the lens mounting portion101and the center of the imaging element110.

In addition, a locking portion104for stopping the rotation of the interchangeable lens2at the time of installing the interchangeable lens2in the imaging device1is provided on the lens mounting portion101. A lens release button124is biased by a biasing member such as a spring, not shown in the drawing, which is integrally formed with the locking portion104to be continuous with the locking portion104. When the lens release button124is pressed, the locking portion104is operated in a direction of the optical axis149in association with the pressing operation, so that locking is released from a concave portion404(FIG. 4) of the interchangeable lens2, and thus it is possible to rotate and remove the interchangeable lens2.

A power supply button120and a recording (REC) button121are provided on a left side of the imaging device1when seen from the subject side. When the power supply button120is pressed in a power OFF state, a power ON state is set, which allows imaging to be performed. When the power ON state is set, a through image of imaging is displayed on a display panel131of a panel unit130which is installed on the rear side of the imaging device1. A rotation dial122is provided on the left side of the imaging device1. It is possible to change a set F-number by rotating the rotation dial122. In addition, a mode selection dial123is provided on the left side of the imaging device1. It is possible to change an imaging mode by rotating the mode selection dial123. In the present embodiment, the converter lens102of the imaging device1reduces rays of light to approximately 0.65 times using a lens group constituted by a plurality of optical members and forms an image on the imaging element110having a 1-inch size of approximately 13.2 mm by approximately 8.8 mm.

FIG. 3illustrates an example of a functional block diagram of the imaging device.

The imaging device1includes the interchangeable lens2to a work memory unit353. When a user operates the power supply button120provided in the imaging device1, a power switch301is pressed and a signal indicating that the power switch301has been pressed is transmitted to a control IC351. Thereby, the power supply of the imaging device1is turned on, and thus a standby state is set. When the user presses the REC button121in the standby state, a REC switch302detects that the REC button121has been pressed. Thereby, a recording process is started, so that the writing of digital video data in the recording unit140is started. When the user presses the REC button121again in this state, the recording process is terminated and the state returns to a standby state, so that writing of digital video data in the recording unit140is terminated.

An electronic contact point portion103performs data communication with the interchangeable lens2. The control IC351is a CPU and controls the entire imaging device1. Specifically, the control IC351transmits power to the interchangeable lens2through the electronic contact point portion103, receives lens identification information from the interchangeable lens2, and performs data communication such as transmission of a control signal of an autofocus or an F-number to the interchangeable lens2. If the power supply of the imaging device1is turned on in a state where the interchangeable lens2is mounted or when the interchangeable lens2is mounted in a state where the power supply of the imaging device1is turned on, power is first supplied to the interchangeable lens2through the electronic contact point portion103. The interchangeable lens2supplied with power transmits lens identification information of the interchangeable lens2to the imaging device1. The control IC351receives the lens identification information from the electronic contact point portion103and acquires the equivalent lens identification information from a lens identification information group which is stored in a program memory unit311in advance.

The control IC351acquires information of a limit F-number associated with lens identification information from the program memory unit311. The information of the limit F-number is information having the smallest F-number in which a decrease in the amount of peripheral light is inconspicuous after the amount of peripheral light is corrected by the imaging device1including the converter lens102. The control IC351transmits a control signal which is set to a value equal to or greater than the limit F-number to the interchangeable lens2through the electronic contact point portion103to control an F-number.

The F-number can be changed by operating the rotation dial122. When the user rotates the rotation dial122in a standby state or during REC, a rotation dial detection switch303detects the operation. The rotation dial detection switch303transmits a detection signal to the control IC351, and the control IC351changes an F-number on the basis of the amount of rotation of the rotation dial122in the range of the F-number equal to or greater than the limit F-number.

A light flux having passed through the interchangeable lens2and the converter lens102is photoelectrically converted into an electrical signal by the imaging element110. The electrical signal obtained through the photoelectric conversion is input to a control unit350of a main substrate310. An image processing unit352included in the control unit350converts a signal charge transmitted from the imaging element110into digital video data of a luminance signal and a color signal. The work memory unit353which is a volatile storage unit is used as a work area of the control IC351.

In addition, the control IC351acquires peripheral light amount compensation data associated with a lens identification information group from the program memory unit311and transmits the peripheral light amount compensation data to the image processing unit352. The image processing unit352performs peripheral light amount compensation on an electrical signal which is output by the imaging element110and then converts the electrical signal having been subjected to the peripheral light amount compensation into digital video data on the basis of the peripheral light amount compensation data. The converted digital video data is temporarily recorded in the work memory unit353and is recorded in the recording unit140under the control of the control IC351. The digital video data is transmitted from the image processing unit352to a panel image processing unit132provided in the panel unit130. The digital video data transmitted to the panel image processing unit132is converted into a format for performing display on the display panel131. In addition, the display panel131displays the digital video data as a through image at the time of imaging. Meanwhile, various icons stored in the program memory unit311in advance can also be displayed on the display panel131.

FIG. 4is a perspective view of an interchangeable lens when viewed from the rear side of an optical axis.FIGS. 5A and 5Bare perspective views of a main configuration of the imaging device1.FIGS. 6A and 6Bare diagrams illustrating a configuration of a lens mounting fixing member.FIGS. 7A and 7Bare perspective views of a converter lens driving member.

The interchangeable lens2is provided with a lens-side mounting member401(FIG. 9) which is fitted to the lens mounting portion101(FIG. 5A) provided in the imaging device1. The lens-side mounting member401includes a bayonet claw portion402, an abutting portion403which is a portion of the bayonet claw portion402, and a concave portion404that holds the interchangeable lens2by engaging with the locking portion104of the imaging device1illustrated inFIG. 4.

As illustrated inFIG. 5B, the converter lens102is held (fixed) by a converter lens holding member501using a fastening member such as a screw. Guide pins502which are protrusion portions are provided on the outer circumferential surface of the converter lens holding member501at a plurality of locations at predetermined intervals. In the present embodiment, the guide pins502are disposed around the optical axis149at three locations at equal intervals of 120 degrees.

In addition, as illustrated inFIG. 6A, guide grooves601which are first groove portions are disposed in the lens mounting fixing member201at a plurality of locations at predetermined intervals. In the present embodiment, the guide grooves601are disposed around the optical axis149at three locations at equal intervals of 120 degrees. Thereby, the guide pins502of the converter lens holding member501(FIG. 5B) is slidable. In addition, a converter lens driving member503is rotatably fitted to a driving member fitting portion602at the rear of the lens mounting fixing member201.

In addition, as illustrated inFIG. 6B, a portion of the converter lens driving member503to be described later is inserted into the lens mounting fixing member201, and a driving member insertion portion603is provided to protrude inside the lens mounting fixing member201. The driving member insertion portion603is open to penetrate the lens mounting fixing member201.

In addition, as illustrated inFIGS. 7A and 7B, the converter lens driving member503includes a cylindrical portion701and a bayonet claw engagement portion702. The cylindrical portion701is rotatably fitted to the driving member fitting portion602of the lens mounting fixing member201. In addition, the bayonet claw engagement portion702engages with the bayonet claw portion402of the interchangeable lens2with a bayonet system. With such a configuration, it is possible to drive the converter lens driving member503.

Guide cam grooves703which are second groove portions are disposed at a plurality of locations to penetrate the outer circumferential surface of the cylindrical portion701. The guide pin502(FIG. 5B) is inserted into the guide cam groove703. Thereby, the converter lens holding member501is driven in association with an operation of mounting the interchangeable lens2and an operation of removing the interchangeable lens2. The shape of the guide cam groove703will be described later. The bayonet claw engagement portion702includes an abutting portion704at the time of mounting and an abutting portion705at the time of separation. The abutting portion704at the time of mounting abuts on the abutting portion403of the bayonet claw portion402when the interchangeable lens2is mounted on the imaging device1. The abutting portion705at the time of separation abuts on a side opposite to the abutting portion403of the bayonet claw portion402when the interchangeable lens2is separated therefrom, that is, removed from the imaging device1. The guide pin502is inserted into both the guide groove601of the lens mounting fixing member201and the guide cam groove703of the converter lens driving member503.

FIGS. 8A and 8Bare cross-sectional views of a converter lens driving mechanism.

FIG. 8Aillustrates the converter lens driving mechanism in a state where the interchangeable lens is removed from the imaging device.FIG. 8Billustrates the converter lens driving mechanism in a state where the interchangeable lens is fixed to the imaging device. Meanwhile, inFIG. 8Band the subsequent drawings, a lens tube portion of the interchangeable lens2is omitted, and only the lens-side mounting member401fixed to the imaging device1is illustrated.

If the interchangeable lens2illustrated inFIG. 8Ais removed from the imaging device1, the converter lens102is moved (retreated) to a position which is not a predetermined optical position. When the interchangeable lens2is mounted and fixed to the imaging device1, the converter lens102is disposed at a predetermined optical position illustrated inFIG. 8B. Hereinafter, the operation of the converter lens driving mechanism will be described by taking a case where the interchangeable lens2is mounted on the imaging device1as an example.

FIG. 9is a diagram illustrating a state where the lens-side mounting member401of the interchangeable lens2engages with the converter lens driving member503. In addition,FIGS. 10 to 12are diagrams illustrating mounting of the interchangeable lens on the imaging device.

FIG. 10illustrates a state where the interchangeable lens2is removed from the imaging device1.FIG. 11illustrates a state where the interchangeable lens2is mounted on the imaging device1and is not rotated.FIG. 12illustrates a state where the interchangeable lens2is rotated until the interchangeable lens2is fixed. In addition,FIG. 13is a diagram illustrating the development of the guide cam groove703provided in the cylindrical portion701of the converter lens driving member503.

When the interchangeable lens2is mounted on the imaging device1, the interchangeable lens2is brought closer to the imaging device1to engage with the bayonet claw portion402of the interchangeable lens2and the lens mounting portion101and the lens-side mounting member401of the interchangeable lens2abut on each other. In this case, the bayonet claw portion402of the interchangeable lens2engages with the bayonet claw engagement portion702of the converter lens driving member503(FIGS. 9 and 11).

When the interchangeable lens2is rotated clockwise with respect to the imaging device1when seen from a subject side centering on the optical axis149, the abutting portion403of the bayonet claw portion402and the abutting portion704at the time of mounting of the bayonet claw engagement portion702are made to abut each other. Thereby, an operational force when the interchangeable lens2is mounted is transmitted to the converter lens driving member503. When the interchangeable lens2is further rotated, the converter lens driving member503is rotated due to a force transmitted from the interchangeable lens2. When the converter lens driving member503is rotated, the guide pin502of the converter lens holding member501is operated while sliding on the inner wall portion of the guide cam groove703.

In a state in which the interchangeable lens2is removed from the imaging device1, the guide pin502is positioned at a lens release point1101of the guide cam groove703illustrated inFIG. 13. The guide cam groove703includes a cam track L1and a cam track L2. The cam track L1has a first inner wall portion extending in a direction perpendicular to the optical axis. The cam track L2is formed to be continuous with the cam track L1and has a second inner wall portion extending while forming a predetermined angle with respect to the cam track L1.

In the guide cam groove703, a cam groove central line is formed on the same surface as a plane perpendicular to the optical axis149in the cam track L1, and the guide pin502only slides on the first inner wall portion of the cam track L1. Therefore, since the converter lens holding member501is not operated while the guide pin502is operated along the cam track L1, the converter lens102fixed to the converter lens holding member501also does not operate, and the converter lens102is maintained at a position illustrated inFIG. 8A.

When the interchangeable lens2is further rotated, the guide pin502of the converter lens holding member501enters the cam track L2(FIG. 13) formed to be continuous with the cam track L1. The cam track L2is formed to form oblique sides of a circumferential direction moving distance X and an optical axis direction moving distance Y. Therefore, the guide pin502slides along the second inner wall portion of the cam track L2in association with a rotation operation of the converter lens driving member503, so that the converter lens holding member501is moved in the optical axis direction. When the interchangeable lens2is further rotated, the concave portion404of the interchangeable lens2reaches the locking portion104of the imaging device1, and the interchangeable lens2is fixed to the imaging device1. In this case, the guide pin502reaches a lens locking point1102of the guide cam groove703, and the converter lens102fixed to the converter lens holding member501is disposed at a predetermined optical position (first position). The first position is an optical position where an image of a light flux from the converter lens102is formed on the imaging element110. That is, when the mounting of the interchangeable lens2on the lens mounting portion101is completed, the converter lens102completes movement to the first position. With the above-described configuration, it is possible to move the converter lens102to the first position in the optical axis direction in association with a rotation operation when the interchangeable lens2is mounted.

If the interchangeable lens2is removed from the imaging device1, the lens release button124is pressed, and the interchangeable lens2is rotated in a direction opposite to a direction when the interchangeable lens2is mounted, so that the respective members are driven in an order reverse to the above-described operations at the time of mounting, and thus the interchangeable lens2can be removed. Specifically, the cam track L2moves the converter lens holding member501in the optical axis direction in association with a rotation operation of the converter lens driving member503when the interchangeable lens2is removed from the imaging device1. That is, the guide pin502slides along the inner wall portion of the guide cam groove703in association with the rotation of the converter lens driving member503accompanying the rotation of the interchangeable lens2, so that the converter lens holding member501is moved in the optical axis direction. Thereby, the converter lens102is retreated to a second position where an image of a light flux from the converter lens102is not formed on the imaging element110. The second position is a position when the converter lens is moved from the above-described first position in a direction in which a light flux from an optical system expands.

Referring toFIG. 13, the guide cam groove703of the converter lens102will be described. As described above, in the guide cam groove703, the cam track L1in which the converter lens102is not moved and the cam track L2in which the converter lens102is moved are formed to be continuous with each other. When the cam track L2for driving the converter lens102is operated by the circumferential direction moving distance X, the converter lens102is operated in a direction of the optical axis149over the optical axis direction moving distance Y. In this case, it is preferable that the circumferential direction moving distance X be set as short as possible until immediately before the interchangeable lens2is mounted and in a range in which the converter lens102can be moved to a use position. With such a configuration, the converter lens102does not have an optical arrangement in an imaging state immediately before the interchangeable lens2is fixed to the imaging device1. Thereby, it is possible to reduce a likelihood that the imaging element110will be burned due to sunlight incident on the imaging element110, or the like even during an operation of mounting the interchangeable lens2.

In addition, the optical axis direction moving distance Y determines the amount of retreat of the converter lens102. When an angle θ formed between the cam track L2and the circumferential direction moving distance X becomes larger, an operating load of the converter lens driving member503in the cam track L2increases due to a component force. Therefore, it is preferable that the angle θ be appropriately determined by a balance amount between the amount of retreat, an operating load, and a locking position of the interchangeable lens2.

FIG. 14is a diagram illustrating a relationship between a light flux from a converter lens and an imaging element.

A light flux1201from the converter lens102includes a light flux converging on the imaging element110of the imaging device1. When the converter lens102is exposed, there is a possibility that the performance of the imaging element110may be impaired due to the incidence of sunlight and the like on the converter lens102depending on use conditions other than imaging.

In the imaging device of the present embodiment, the converter lens102is moved in association with the interchangeable lens2, and thus the light flux1201of which the image is formed by the imaging element110is moved to a position different from a position where an image was to be originally formed. Specifically, as illustrated inFIG. 14, the imaging element110is moved by the optical axis direction moving distance Y with respect to the light flux1201of the converter lens102. In this case, a cut surface S2of the light flux1201at the position of the imaging element110in a state where the interchangeable lens2is removed from the imaging device1is larger than a cut surface51of the light flux1201at the position of the imaging element110in a state where the interchangeable lens2is mounted on the imaging device1. Therefore, an energy per unit area can be reduced. That is, the image forming position of the light flux1201of the converter lens102is moved, thereby reducing a likelihood that the imaging element110will be burned due to sunlight and the like incident on the imaging element110. As described above, according to the imaging device of the present embodiment, it is possible to prevent the imaging element from being burned when an interchangeable lens is removed from the imaging device.

Other Embodiments