Optical apparatus

An optical apparatus includes a heat sink radiating the image sensor, a cooling fan unit configured to cool the heat sink, and a first lens barrel including a hollow portion configured to guide light to the image sensor. The first lens barrel holds the cooling fan unit and house the holder unit movably in the hollow portion in an optical axis direction of the image pickup optical system. The holder unit includes a first inlet and a first outlet. The first lens barrel includes a second inlet for taking in external air and a second outlet for exhausting the external air taken in through the second inlet. The first inlet is connected to the second inlet and the first outlet is connected to the second outlet when the holder unit is positioned in the hollow portion of the first lens barrel.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an optical apparatus such as an image sensor unit, a lens barrel unit, a lens integrated camera, and a microscope.

2. Description of the Related Art

Recently, optical apparatuses such as a digital video camera and a digital still camera have been increasingly required to be downsized. For example, a so-called inner focus zoom type is smaller than a front focus type because a front lens and an image sensor are fixed while a magnification-varying unit and a focus unit are made movable in an optical axis direction inside a lens barrel. A retractable lens barrel is also smaller because the image sensor is fixed while the magnification-varying unit including the front lens is moved in the optical axis direction. However, a heating value of the image sensor generates tends to increase due to an increasing number of pixels, and a heat radiating measure becomes necessary.

Japanese Patent No. 4194221 discloses a retractable lens barrel configured to move a front lens in varying the magnification. Japanese Patent Laid-open No. 2010-56995 discloses a camera including a Peltier element for heat radiations of an image sensor.

The structure of Japanese Patent No. 4194221, in which a first lens unit optical system has the front lens is made of a large glass and hence is heavy, is disadvantageous for quick zooming and smooth moving-image capturing. In addition, a smaller F-number leads to a larger optical system, and requires a large complicated drive mechanism. It is difficult to mount the structure of Japanese Patent Laid-open No. 2010-56995 in a small camera, because the Peltier element and heat transfer structure are too complicated.

SUMMARY OF THE INVENTION

The present invention provides a small optical apparatus having a high heat radiating performance.

An optical apparatus according to the present invention includes an image sensor configured to photoelectrically convert an optical image of an object formed by an image pickup optical system, a heat sink configured to radiate heat generated by the image sensor, a holder unit configured to hold the image sensor and the heat sink, a cooling fan unit including a cooling fan configured to cool the heat sink, and a first lens barrel including a hollow portion configured to guide light from the image pickup optical system to the image sensor, the first lens barrel holding the cooling fan unit and housing the holder unit movably in the hollow portion in an optical axis direction of the image pickup optical system. The holder unit includes a first inlet for taking external air into the heat sink and a first outlet for exhausting the external air taken in through the first inlet. The first lens barrel includes a second inlet for taking in the external air and a second outlet for exhausting the external air taken in through the second inlet. The first inlet is connected to the second inlet and the first outlet is connected to the second outlet when the holder unit is positioned in the hollow portion of the first lens barrel.

DESCRIPTION OF THE EMBODIMENTS

FIG. 1is a block diagram of an image pickup apparatus (optical apparatus) according to this embodiment of the present invention. The image pickup apparatus is, for example, a lens integrated camera such as a digital video camera or a digital still camera, or a microscope. The left side inFIG. 1is an object side.

InFIG. 1, reference numeral L1denotes a fixed first lens unit (fixed unit) closest to the object side. Reference numerals L2and L3denote a second lens unit and a third lens unit, respectively, as magnification-varying lens units configured to move in an optical axis direction to vary the magnification. Reference numeral L4denotes a fixed fourth lens unit, and reference numeral L5denotes a fifth lens unit (focus lens) configured to move in the optical axis direction for focusing.

The first lens unit L1to the fifth lens unit L5constitute an image pickup optical system configured to form an optical image of an object. The image pickup optical system according to this embodiment moves an image pickup plane of an image sensor in the optical axis direction in varying the magnification. InFIG. 1, “z” denotes the optical axis of the image pickup optical system. The image pickup optical system is housed in a lens barrel unit (second lens barrel). A structure of providing focusing by the last lens unit reduces a size of the lens barrel unit.

Reference numeral1denotes a fixed lens barrel configured to hold the first lens unit L1. Reference numeral2denotes a moving member (lens holding frame) configured to hold the second lens unit L2. Reference numeral3denotes a moving member (lens holding frame) configured to hold the third lens unit L3. Reference numeral4denotes a fixed member configured to hold the fourth lens unit L4. Reference numeral5denotes a moving member (lens holding frame) configured to hold the fifth lens unit L5. The moving member2, the moving member3, and the moving member5are movably supported in the direction of the optical axis Z of the image pickup optical system.

Reference numeral6denotes a diaphragm unit that changes an aperture diameter of the optical system. The diaphragm unit6moves aperture blades within a plane orthogonal to the optical axis through a drive unit6a, thereby changing the aperture diameter. The diaphragm unit6adjusts the light quantity entering the image sensor. The aperture diameter is detected by a diaphragm detector34, and the drive unit6ais driven by a diaphragm driver37.

An image sensor unit30includes the image sensor107and a filter108, is held by a holder unit130, and is moved in the optical axis direction of the image pickup optical system in varying the magnification. The image sensor107includes a photoelectric conversion element, such as such as a CCD sensor or a CMOS sensor, configured to photoelectrically convert the optical image formed by the image pickup optical system. The filter108includes an optical low-pass filter configured to restrict a light component having a spatial frequency of the light passing from the image pickup optical system which is higher than that of the image sensor107, and an infrared cutting filter configured to cut the infrared light. The image sensor107and the filter108are illustrated inFIGS. 3A and 3Bto be described later.

The image sensor107outputs an image signal to a camera signal processor31. The camera signal processor31is mounted onto a substrate105to be described later. The camera signal processor31amplifies and gamma-corrects the output image signal from the image sensor unit30. The signal amplified and gamma-corrected by the camera signal processor31is output to a microcomputer32.

The microcomputer32is a controller (control circuit) configured to receive multiple signals and provide signal processing thereto and configured to output multiple signals in response to an input signal so as to, for example, control the optical apparatus. The microcomputer32includes a processor such as a CPU or a MPU. Reference numeral33denotes a recorder configured to record an image signal processed by the microcomputer32, as well as a recording condition, for example.

The diaphragm detector34is configured to detect a rotational position of a driving magnet of the drive unit6aby a Hall element. In response to an input signal from the camera signal processor31and an input signal such as a rotational amount of the diaphragm drive unit6afrom the diaphragm detector34, the microcomputer32outputs a diaphragm drive signal to the diaphragm driver37so as to adjust the light quantity.

Reference numeral50denotes a zoom switch through which a magnification-varying operation is instructed. Reference numeral51denotes a focus switch through which a manual focusing operation (focusing operation) is instructed by a user. Reference numeral52denotes a power switch. Reference numeral7denotes a cam ring that holds movable a magnification-varying optical system in the optical axis direction. Reference numeral8denotes a guide ring including an elongate hole that guides the magnification-varying optical system in a straightforward direction.

When the zoom motor10is rotated, the cam ring7is rotated about the optical axis at a fixed position due to an engagement between a gear10aattached to an output shaft of the zoom motor10and a gear portion7aprovided to the cam ring7.

The moving members2and3and the diaphragm unit6have cam followers substantially equally arranged (at circumferentially 120-degree intervals) on their circumferences. The positions of the cam followers are changed in the optical axis direction through a cam groove of the cam ring7and the elongate hole of the straightforward moving guide so as to vary the magnification. An arc-shaped encoder9is attached to an outer circumference of the cam ring7and a zoom position is detected by a zoom position detector20attached to a fixed lens barrel.

The moving member (lens holding frame)5holds the fifth lens unit L5, has an ultrasonic oscillator11driven by a fifth lens unit driver36. The ultrasonic oscillator11constitutes an ultrasonic motor moved and stopped by the friction with a slider12in the optical axis direction. The moving member5is movably supported in the optical axis direction of the image pickup optical system by a pair of guide bars (not illustrated) extending in parallel to each other in the optical axis direction. The moving member5has an encoder (not illustrated) attached thereto so that its position in the optical axis direction is detected by a fifth lens unit position detector21.

Similarly, the holder unit130holds the image sensor unit30and has an ultrasonic oscillator13that constitutes the ultrasonic motor moved and stopped by the friction with the slider14in the optical axis direction through friction. The ultrasonic oscillator13is driven by an image sensor driver15.

An ultrasonic motor is a friction motor that converts vibrations caused by a piezoelectric effect into actions. The ultrasonic motor deforms the ultrasonic oscillator made of a piezoelectric ceramics oscillator by applying the voltage to it, generates a frictional force using its positional change, and converts it into a rotation or in a linear movement.

Specifically, a driver of the image sensor unit30moves the holder unit130to be described later inside a hollow of the fixed lens barrel110with respect to the fixed lens barrel110(along the optical axis direction of the image pickup optical system). The driver is not limited to the ultrasonic motor and may use a stepping motor or a VCM, for example. The microcomputer32controls the movement (driving) of the image sensor107by the image sensor driver15.

FIGS. 2A and 2Bare perspective views of an image sensor unit100according to the present embodiment.FIG. 2Aillustrates a wide-angle state, andFIG. 2Billustrates a telephoto state.FIGS. 3A and 3Bare cross-sectional views along the optical axis z of the image sensor unit100.FIG. 3Aillustrates a wide-angle state, andFIG. 3Billustrates a telephoto state.FIGS. 4A and 4Bare perspective views of the image sensor unit100.FIG. 4Aillustrates the image sensor unit100from which a cooling fan unit150is detached, andFIG. 4Billustrates the image sensor unit100from which the holder unit130is further detached.

As illustrated inFIG. 4B, the image sensor unit (the optical apparatus)100includes the fixed lens barrel110, the holder unit130, and the cooling fan unit150.

The fixed lens barrel110of the image sensor unit100is fixed to the lens barrel unit (second lens barrel) of the image pickup optical system. The image sensor unit100and the lens barrel unit of the image pickup optical system to which the image sensor unit100is attached serve as the optical apparatus according to this embodiment.

The holder unit130is movably supported in the optical axis direction of the image pickup optical system by a pair of guide bars103and104extending in parallel to each other in the optical axis direction. The holder unit130is provided with an image sensor position detector22that is a detector configured to detect the position of the image sensor107in the optical axis direction. The image sensor position detector22is, for example, an encoder (not illustrated) that includes a light emitting element, a light receiving element, and a scale.

When the power switch52of the camera is turned on, the zoom position detector20detects the zoom position (magnification-varying position). The moving member5and the holder unit130are moved in the optical axis direction and stopped at a target position so that by the fifth lens unit position detector21and the image sensor position detector22can have corresponding values.

The microcomputer32controls the fifth lens unit driver36based on the image signal from the image sensor107, oscillates the ultrasonic oscillator11through a drive signal, and moves the moving member5in the optical axis direction for focusing.

When the zoom switch50is operated, the microcomputer32determines how a moving direction and a moving speed are operated and performs zooming. The zoom motor10receives a drive signal from a zoom driver35in response to a control signal from the microcomputer32and rotates the cam ring7in a direction and an amount that correspond to the operation of the zoom switch50. At this time, the microcomputer32performs a feedback control based on a value of the zoom position detector20that detects the position of the cam ring7.

The ultrasonic motor includes the ultrasonic oscillator11and the slider12, receives a drive signal from the fifth lens unit, driver36in response to a control signal from the microcomputer32, drives the moving member5in a direction and an amount that correspond to the operation of the zoom switch50. At this time, the microcomputer32performs a feedback control based on a value of the fifth lens unit position detector21that detects the position of the moving member5.

Similarly, the ultrasonic motor includes the ultrasonic oscillator13and the slider14, receives a drive signal from the image sensor driver15in response to a control signal from the microcomputer32, and drives the image sensor107in a direction and an amount that correspond to the operation of the zoom switch50. At this time, the microcomputer32performs a feedback control based on a detection result of the image sensor position detector22that detects the position of the image sensor107.

Although the magnification is varied by moving the image sensor107in this embodiment, the present invention is also applicable to focusing by moving the image sensor107. For example, a focus detection by a contrast detecting method is performed by detecting a contrast peak position of the object image formed by the image sensor107while sequentially changing a distance between a focus position of the image pickup optical system and the image sensor107. In this case, the image sensor107is moved in the optical axis direction instead of moving the focus lens in the optical axis direction.

As illustrated inFIGS. 2A and 2B, the fixed lens barrel110is a first lens barrel including a fixing portion (first fixing portion)111disposed on a front side (the object side) and an attachment portion112disposed on a rear side (opposite to the object), to which the holder unit130is attached. The fixed lens barrel110further includes the hollow portion HP that guides the light from the image pickup optical system to the image sensor107. The fixed lens barrel110houses, in the hollow portion HP, the holder unit130movably in the optical axis direction of the image pickup optical system. The holder unit130inserted in the hollow portion HP facilitates dust proofing and shields unnecessary light from the image sensor107. The fixed lens barrel110holds the cooling fan unit150.

The fixing portion111has a hollow cylinder shape. The fixing portion111is fixedly connected to the lens barrel unit (second lens barrel) of the image pickup optical system on its object side, and the back surface of the fixing portion111is fixed to the attachment portion112. As illustrated inFIGS. 3A and 3B, an opening111ais formed at the center of the fixing portion111and takes in image light. The opening111aconstitutes a hollow portion.

As illustrated inFIG. 4B, the attachment portion112has a pair of openings (second inlets)113aat its top and bottom and an opening (second outlet)113bat its back end. A vertical direction is parallel to a widthwise direction of the image sensor107. The pair of openings113aare connected to a pair of respective openings (first inlets)131of the holder unit130and disposed outside the openings131. Each of the openings113ais an inlet for taking in external air. The pair of openings113aand the pair of openings131may be disposed on the right and left sides of the image sensor unit100in a horizontal direction. The horizontal direction is parallel to a lengthwise direction of the image sensor107.

The opening113ais rectangular and larger than the opening131. The opening131is connected to the outside through the opening113awhen the image sensor107is positioned between a wide-angle position (first position) illustrated inFIG. 3Aand a telephoto position (second position) illustrated inFIG. 3B. This configuration allows the opening131to take in external air even when the image sensor107is moved in the optical axis direction. The first position and the second position are not limited to the wide-angle position and the telephoto position, for example, when the image sensor107is used for focusing as described above.

The opening113bis an outlet of air taken in through the openings113aand is connected to an opening132(first outlet) of the holder unit130when the image sensor107is positioned between the wide-angle position and the telephoto position. This configuration allows the opening132to exhaust the air when the image sensor107is positioned between the positions in the optical axis direction. As a result, a cooling efficiency is maintained. The opening113ahas a hollow cross shape and is larger than the opening132. The opening113bserves to send air inside the lens barrel110taken in through the opening113a, to the cooling fan unit150.

The attachment portion112includes a holder114afixedly holding the guide bar103and a holder (second fixing portion)114dfixedly holding the guide bar104. The guide bars103and104constitute a guide unit that moves the holder unit130relative to the fixed lens barrel110in the optical axis direction of the image pickup optical system in the hollow portion HP of the fixed lens barrel110. The holder114dalso serves as a screw fixer for fixing a screw160, and this multi-functionality contributes to downsizing.

The attachment portion112further includes screw fixers114band114cto which the screws160are fixed. The holders114aand114dand the screw fixers114band114care provided at four corners of the opening113bat the back end of the attachment portion112. The cooling fan unit150is fixed by the screws160to the back end of the attachment portion112.

The holder unit130holds the image sensor107, the filter108, and a heat sink140. The heat sink140includes a holding member141holding the image sensor107and a plurality of cooling fins142standing on the holding member141, and is a heat radiating unit for radiating the heat generated by the image sensor107. The holding member141and the cooling fins142are made of metal such as copper having a high thermal conductivity.

The holding member141has a recess-shaped section as illustrated inFIGS. 3A and 3B, but may have a flat-plate shaped section. The holding member141is thermally connected to the image sensor107. The heat generated by the image sensor107is transferred to the holding member141and then transferred to the cooling fins142. In the present embodiment, each cooling fin142has a plate shape extending in the vertical direction, but may have a plate shape extending in the horizontal direction, a column shape, or a needle shape. The column-shaped or needle-shaped cooling fins may be arranged in a grid or arranged concentrically around the optical axis.

The holder unit130includes the openings131and132, a sleeve133connected to the guide bar103, and a rotation preventive hole (not illustrated). The holder unit130is configured to move in the optical axis direction along the guide bars103and104. The microcomputer32controls the movement driven by the drive unit.

The holder unit130includes the pair of openings131at its top and bottom and the opening132on its back surface. The pair of openings131are provided next to the cooling fins142of the heat sink140and are the inlets for taking external air into the heat sink140. Spaces between the cooling fins142of the heat sink140serve as flow paths of the air taken in through the opening131. Intake and exhaust of the external air are achieved by a cooling fan of the cooling fan unit150. These flow paths of the air are connected to the opening132. The cooling fins142are cooled by passing air. The hollow portion HP of the fixed lens barrel110constitutes part of the flow paths of the external air cooling the heat sink140.

When the image sensor107is positioned at the wide-angle position illustrated inFIG. 3A, the openings131communicate with left sides (left halves) of the respective openings113aillustrated inFIG. 3A. When the image sensor107is positioned at the wide-angle position illustrated inFIG. 3B, the openings131communicate with right sides (right halves) of the respective openings113aillustrated inFIG. 3B. Since the openings113ado not block the openings131when the holder unit130is moved in the optical axis direction, the intake area for external air is maintained constant. The openings113aand131are arranged in a direction (the widthwise direction of the image sensor107) vertical to the optical axis of the image pickup optical system. The air may flow in an opposite direction (the inlets and the outlets may be reversed), and thus the first outlet and the second outlet may be arranged in a direction vertical to the optical axis of the image pickup optical system.

The cooling fan unit150includes a rectangular parallelepiped housing in which the cooling fan (an air blower) (not illustrated) is provided. The cooling fan cools the heat sink140. The cooling fan unit150is another heat radiator for radiating the heat generated by the image sensor107. In this embodiment, as described above, the heat radiating units are disposed closer to the rear side in the optical axis direction than the image sensor107.

The cooling fan is supplied with power from a power unit (not illustrated) and rotates. A rotational shaft of the cooling fan is disposed, for example, on the optical axis of the image pickup optical system.

The housing of the cooling fan unit150includes a front surface151, a back surface152, and a pair of side surfaces153as illustrated inFIG. 4A. The front surface151and the back surface152are vertical to the optical axis. The front surface151has an opening (not illustrated), whereas the back surface152has no opening. The opening of the front surface151has no limitation on its shape and serves as an inlet. Each of the side surfaces153is provided with a rectangular opening153a. The opening153aserves as an outlet. The cooling fan unit150according to this embodiment is a centrifugal fan that takes in air from the opening of the front surface151and exhausts the air through the opening153aof each side surface153to the outside of the lens barrel110, and an air flow path has an L shape.

The cooling fan unit150may be an axial flow fan in which the openings153aof the side surfaces153are sealed and the back surface152is provided with an opening so that air flows from the opening of the front surface151to the opening of the back surface152in the optical axis direction. Alternatively, the cooling fan may rotate oppositely so that the inlet and the outlet are reversed. The cooling fan unit150has screw holes at three corners154and is attached to the opening113bof the attachment portion112by the screws160.

The image sensor107, the heat sink140, and the cooling fan unit150are arranged in this order from the object side in the optical axis direction. The heat radiating units are disposed closer to the rear side (opposite to the object) than the image sensor107. The image pickup optical system, the flow paths of external air, and the cooling fan overlap each other in the optical axis direction of the image pickup optical system. This overlap leads to a small projected shape viewed from the front side of the lens barrel of the image pickup optical system, which means that the lens barrel is downsized and therefore the image sensor unit100and the image pickup apparatus are downsized.

The external air having passed through the cooling fins142that transfers and radiates the heat of the image sensor107passes through the opening132and the opening113bof the holder unit130, and is exhausted by the cooling fan unit150in an arrow A direction illustrated inFIG. 2A. The opening113bdoes not block the opening132when the holder unit130is moved in the optical axis direction, and the opening areas of the outlets of the external air passing through the cooling fins142are maintained constant. The flow speed of air in the flow paths can be therefore maintained constant even when the holder unit130is moved in the optical axis direction, thereby achieving efficient cooling as designed.

InFIGS. 3A and 3B, the holder unit130is provided with a housing134that houses the filter108, and a boss (not illustrated) to which the holding member141is attached. The housing134is disposed closer to the object side in the optical axis direction than the image sensor107. The filter108is fixed onto the housing134by an elastic force applied by an elastic member106. The elastic member106is attached to the housing134and pushed against the filter108by the image sensor107, covering the periphery of a surface (protective glass surface) (not illustrated) of the image sensor107through which surface the light from the image pickup optical system enters, so as to achieve dust proofing inside the protective glass.

The substrate105onto which the image sensor107is mounted is connected with wires102for transmitting a signal photoelectrically converted by the image sensor107and a control signal from the microcomputer32.

Specifically, as illustrated inFIG. 3B, the substrate105is provided to the holder unit130, and includes a first substrate105aconnected to the image sensor107, a second substrate105bprovided to the fixed lens barrel110, and the wires102. The wires102serve as flexible, third substrates connecting the first substrate105aand the second substrate105bwith each other. The first substrate105aand the second substrate105bhave bent shapes. The second substrate105bof the substrate105may have the microcomputer32and the camera signal processor31.

The wires102are flexible printed boards or wires such as small gauge coaxial cables having a high flexibility. The wires102are connected to the outside of the lens barrel110and have lengths appropriate for a smooth movement of the holder unit130in the optical axis direction to vary the magnification, as illustrated inFIGS. 2A and 2BandFIGS. 3A and 3B. The wires102are connected to the first substrate105athrough the openings113aand131, which means the openings113aand131are used for the wires102, thereby achieving multi-functionality and hence downsizing.

Since the inlets and the outlets may be reversed as described above, the wires102may be connected to the first substrate105athrough the first outlet and the second outlet.

The image sensor107has an effective region of 16:9, for example. In this case, a pair of the wires102are disposed in the vertical direction of the fixed lens barrel110so that the wires102protrude above and below the holder unit130. A second driver (the ultrasonic oscillator11and the slider12) of the moving member5and the fifth lens unit position detector (a second detection unit)21configured to detect the position of the focus lens are disposed on one of the right and left sides of the lens barrel of the image pickup optical system. A first drive unit (the ultrasonic oscillator13and the slider14) of the holder unit130, the image sensor position detector (a first detection unit)22, and the guide bars103and104are disposed on one of the right and left sides of the lens barrel of the image pickup optical system. Space in the vertical direction (a first direction) and the horizontal direction (a second direction vertical to the first direction) that are vertical to the optical axis of the image pickup optical system is maximized for the miniaturization.

As described above, this embodiment fixes a first lens unit optical system including a front lens while moving the image sensor107in the optical axis direction. This configuration achieves a magnification-varying optical system having a small diameter of the front lens and a small total optical length, as achieved by a retractable lens including a moving first lens unit optical system. Furthermore, a moving unit can remain relatively small even for a small F-number.

The image sensor107as a heat source is cooled by the flow paths and the cooling fan unit150disposed closer to the rear side in the optical axis than the image sensor107. Thereby a small and efficient optical apparatus can be provided.

This embodiment provides the position detectors for the cam ring7, the moving member (lens holding frame)5, and the holder unit130with the detection units configured to detect their absolute positions, but detectors configured to detect distances positions from reset positions may be used. The driving unit for driving each moving unit may use a stepping motor, etc. drive-controlled based on the number of pulses from the reset positions.

The present invention provides a small optical apparatus having a high heat radiating performance.

This application claims the benefit of Japanese Patent Application No. 2013-175106, filed Aug. 27, 2013, which is hereby incorporated by reference herein in their entirety.