JP2008131251A - Digital camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive digital camera which is not structurally restricted and efficiently cools an imaging device. <P>SOLUTION: A CCD 22 generates much heat during its photographing operation. Especially, when the CCD 22 has many pixels or when high-speed continuous shooting is performed, very high-temperature heat is generated. The heat is conducted to a support part 30a through a silicone sheet 35 or to a side wall 30b. Further, the heat is conducted to a cooling part 30e held at low temperature with outside air taken in through an air vent 11 to be radiated. Electromagnetic radiation of the CCD 22 is reduced as the support part 30a and side wall 30be serve as a shield since a structure member 30 is electrically connected to a ground pattern 32a of a circuit board 32. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a digital camera provided with a mechanism for cooling an image sensor.

  Digital cameras and video cameras are widely used as electronic devices in which a solid-state imaging device package in which a solid-state imaging device chip such as a CCD or CMOS sensor is housed in ceramics or the like is incorporated. In addition, a solid-state imaging device package and a memory are incorporated into a personal computer, a mobile phone, an electronic notebook, and the like to add a photographing function.

  When imaging is performed with an electronic device including a solid-state imaging device package, the temperature of a solid-state imaging device chip, a driving circuit for the solid-state imaging device chip, and the like rise. This is due to heat generation that occurs when charges accumulated in a large number of light receiving elements provided in the solid-state imaging element chip are transferred through a transfer path, and the temperature rises in proportion to the imaging time. For this reason, as the number of pixels of the solid-state imaging device increases and the density increases, a high heat generation temperature has become a problem, and there is a problem that an image captured due to the heat generation is deteriorated or noise is generated. . As a countermeasure to this thermal problem, even if a heat sink, a graphite sheet, or the like is attached to a solid-state imaging device, a high cooling effect cannot be obtained in a small casing such as a digital camera.

On the other hand, various structures for dissipating heat generated from the solid-state imaging device have been proposed. For example, in Patent Document 1, a digital camera provided with a cover that opens laterally has a structure in which a vent hole communicating with outside air is provided in the space between the cover and the main body, and heat is exhausted by a heat sink or heat pipe in this space. Has been. Further, in Patent Document 2, in a digital camera in which a part of an exterior and an internal structural member are bonded to each other with two aluminum thin plates, a single-stroke cooling oil circulation path is provided by carbon printing on the aluminum thin plates. The structure is described. Further, Patent Document 3 describes a structure in which a heat conducting member such as silicon rubber is provided between a CCD and an exterior in an electronic device such as a video camera.
JP 2005-181630 A JP 2005-175854 A JP 2005-64146 A

  However, the structure proposed in Patent Document 1 has a limited scope of application only to a digital camera having a cover that opens sideways, and the structure proposed in Patent Document 2 uses expensive aluminum processed. Therefore, there is a problem in terms of cost, and the structure proposed in Patent Document 3 radiates heat only in the exterior, so that the exterior is overheated.

  SUMMARY An advantage of some aspects of the invention is that it provides an inexpensive digital camera that efficiently cools an image sensor without any structural limitation.

  In order to solve the above-described problems, in the digital camera according to the present invention, a photographing lens, an image sensor that converts subject light incident from the photographing lens into an electric signal, and the image sensor are electrically connected to the image sensor. And a circuit board disposed facing the back surface of the photographic lens, attached to the circuit board, and supporting the imaging device from the back surface so as to be separated from the circuit board, and the rear side of the photographic lens A structural member integrally formed of sheet metal is provided to be fixed at a predetermined position, and a part of the structural member is close to a vent hole provided in the exterior of the camera. Here, the vent hole may be formed obliquely with respect to the surface of the exterior, or a cover that covers the vent hole from the outside may be provided on the exterior. The structural member may be formed of a heat dissipating ceramic instead of the sheet metal.

  The structural member is attached to the circuit board and simultaneously connected to the ground pattern of the circuit board. Here, a side wall facing the side surface of the imaging element may be provided on the structural member.

  Furthermore, in the digital camera, a silicon sheet may be provided between the back surface of the image sensor and the structural member. Alternatively, a flat plate heat-dissipating ceramic having a larger area than the back surface of the image sensor may be sandwiched between the back surface of the image sensor and the structural member. Here, a silicon sheet may be provided between the imaging element and the heat dissipating ceramic, or between the heat dissipating ceramic and the structural member.

  Since the digital camera as described above dissipates heat using an internal structural member, it can be applied to a general digital camera without any significant structural restrictions. In addition, since the structural member is formed of sheet metal or heat-dissipating ceramic, the entire structure member can be configured relatively inexpensively. In the structure described above, the heat of the image sensor is conducted by the structural member and exposed to the outside air to be cooled, so that the exterior can be efficiently radiated without overheating. Furthermore, since the image sensor is separated from the circuit board, the heat of the image sensor is not directly conducted to the circuit board. In addition, since the internal structural members cannot be seen directly from the outside by providing the ventilation holes provided in the exterior at an angle with respect to the surface or covering with a cover, the design characteristics of the digital camera are not impaired. .

  In addition, when the structural member is formed of metal, the structural member is electrically connected to the ground pattern of the circuit board, thereby functioning as a shield against electromagnetic radiation (EMI: Electro Magnetic Interference). At this time, the shielding effect is enhanced by covering not only the bottom surface but also the side surface with the part of the structural member. At this time, heat radiation is enhanced because heat radiation is radiated by sandwiching a heat radiation ceramic between the imaging element and the structural member. Furthermore, the cooling efficiency can be improved by increasing the thermal conductivity using a silicon sheet. Even when the structural member is formed of a heat-dissipating ceramic, the thermal radiation can be enhanced by covering the imaging element with the part of the structural member, not only the bottom surface but also the side surface.

  As shown in FIGS. 1 and 2, the front surface of the digital camera 1 according to the present invention is provided with a photographing lens 3 for photographing a subject, a flash device 2, and the like, and the upper surface for turning the power on and off. A power switch 4, a release switch 5 that is pressed during shooting, and a mode switch 6 that is a sliding switch and selectively switches the operation mode depending on the position of the knob. When the release switch 5 is half-pressed, automatic focus adjustment (AF) and automatic exposure adjustment (AE) are performed, and shooting is performed when the release switch 5 is fully pressed. The mode switch 6 switches between a shooting mode for taking a picture and a playback mode for playing back any shot still image on the LCD 8 on the back.

  On the back surface of the digital camera 1, an LCD 8 for displaying a through image at the time of shooting, a still image that has been shot, a moving image, a menu at the time of setting, and the like is disposed. Further, an operation key 7 composed of four push buttons is arranged next to the LCD 8, and the user operates these to set the number of pixels of an image to be photographed, exposure settings, and the like in the camera. Environment settings such as time can be set. Further, the operation key 7 is used to switch between a moving image shooting mode for shooting a moving image and a still image shooting mode for shooting a still image in the shooting mode, and forcibly causes the flash device 2 to emit light in the still image shooting mode. It is possible to switch between a light emission mode, a non-light emission mode that forcibly prohibits light emission, and an automatic light emission mode that determines whether or not to automatically emit light based on the results of AE and AF.

  On the right side of the digital camera 1 with respect to the shooting direction, there is a memory card 10 for recording a shot image, and a memory card slot 9 having a connector for accommodating the memory card 10 and electrically connecting to a circuit inside the camera. Is provided. The memory card 10 is a medium used for a digital camera for general purposes such as an SD memory card or a compact flash (registered trademark).

  Further, a vent hole 11 is provided on the left side in the photographing direction of the digital camera 1. The ventilation hole 11 has a shape extending long in the thickness direction of the digital camera 1, and a cooling unit 30 e (see FIG. 5) described later is substantially parallel to the surface of the exterior 12 at a position close to the inside of the ventilation hole 11. A plurality are provided. For this reason, the cooling part 30e can be visually recognized through the ventilation hole 11 from the outside, and the designability of the digital camera 1 may be impaired. Therefore, in actuality, when the exterior 12 is made of plastic, it has a relatively large thickness. Therefore, as shown in FIG. 3A, the ventilation holes 11 are formed obliquely with respect to the surface of the exterior 12. The cooling unit 30e is not visible. On the other hand, when the exterior 12 is a sheet metal, it is thin. Therefore, as shown in FIG. 3B, a cover that covers the air holes 11 from the outside is provided on the exterior 12 to make the cooling unit 30e invisible. The form of the vent hole 11 is not limited to this embodiment, and may be provided to extend in the height direction of the digital camera 1 according to the design of the cooling mechanism, or may be a simple circle or square. In addition, the number to be provided may be determined as appropriate. Furthermore, the position at which the vent hole 11 is provided may be the front surface or the back surface of the digital camera 1 according to the position of the cooling unit 30e, and may be appropriately determined according to the design.

  Next, the configuration and function of the digital camera will be described. As shown in FIG. 4, a photographing lens 3 is arranged on the front surface of the digital camera 1 as is well known. The photographing lens 3 is moved in the optical axis direction by a lens driving unit 20 including a motor, a motor driver, a driving mechanism, and the like. The lens driving unit 20 is driven by an instruction signal from the operation control unit 26 that is output in response to an input from the operation key 7. A mechanical shutter 21 that opens and closes the photographing optical path is disposed behind the photographing lens 3 in the optical axis direction. The mechanical shutter 21 is opened and closed by outputting an instruction signal at an appropriate timing when the operation control unit 26 detects pressing of the release switch 5.

  A CCD 22 is disposed behind the mechanical shutter 21 in the optical axis direction as an image sensor. The CCD 22 converts the subject light that has passed through the photographic lens 3 and formed on the light receiving surface into an electrical image signal, and based on the transfer pulse supplied from the drive circuit 24, CDS (correlated double sampling). Output to the circuit 23. Note that a CMOS sensor may be used as the image sensor instead of the CCD 22.

  The CDS circuit 23 is driven based on the drive pulse output from the drive circuit 24, reduces the noise of the imaging signal output from the CCD 22, and outputs it to the A / D conversion circuit 25. The drive pulse of the drive circuit 24 is synchronized with the pulse signal from the operation control unit 26. The A / D conversion circuit 25 converts the input analog imaging signal into digital image data and outputs the digital image data to the operation control unit 26. The image data is subjected to various image processing and output to the compression / decompression unit 28. The compression / decompression unit 28 compresses the input image data and converts it into a data format such as JPEG, and the operation control unit 26 reads out the compressed image data and records it in the memory card 10 as an image file. As described above, the memory card 10 is an external memory for storing an image file, and is electrically connected to the operation control unit 26 via a connector (not shown). In the reproduction mode, the operation control unit 26 reads out the image data recorded on the memory card 10 and reproduces and displays it on the LCD 8.

  As described above, the mode switch 6 is a switch for switching between the two operation modes, and the operation control unit 26 performs an operation according to the set operation mode. As described above, the operation key 7 is used to perform various settings of the digital camera 1, and outputs a signal corresponding to the operation to the operation control unit 26. Appropriate processing such as menu display and setting is performed.

  The LCD 8 outputs various images via the LCD driving circuit 27 by the operation control unit 26. For example, a through image is output in the still image and moving image shooting mode, a still image and a moving image are displayed in the reproduction mode, and a menu for setting is displayed in the operation setting.

  The operation control unit 26 performs overall control of a series of flows in each process performed by the camera system. The operation control unit 26 sequentially performs appropriate output processing for each unit or input processing from each unit while appropriately performing determination processing. is there. The operation control unit 26 controls the lens driving unit 20 based on the input from the operation key 7 in the still image and moving image shooting mode, and outputs a through image to the LCD 8. Further, the operation control unit 26 detects half-pressing of the release switch 5 and performs AE and AF processing, and then detects full-pressing of the release switch 5 and controls the mechanical shutter 21 to perform photographing processing. Further, after the image is captured, the image data input from the A / D conversion circuit 25 is output to the compression / decompression unit 28 to be compressed and recorded in the memory card 10. Conversely, in the playback mode, image data is read from the memory card 10, output to the compression / decompression unit 28, decompressed, and output to the LCD 8.

  Next, the cooling mechanism of the CCD 22 will be described. As shown in FIGS. 5 and 6, the CCD 22 is fixed at a predetermined position behind the lens barrel 13 in a state in which the CCD 22 is attached to the structural member 30 attached on the circuit board 32 with screws 34 by means of an adhesive or the like. Has been. The CCD 22 receives subject light incident along the optical axis L through the taking lens 3 housed in the lens barrel 13. The subject light is received by the micro lens (not shown) via the cover glass 22a in the CCD 22, and then converted into an electrical image signal.

  The circuit board 32 is a printed circuit board on which a circuit for processing an imaging signal such as the CDS circuit 23 described above, a control circuit for realizing an operation control unit 26 for controlling an imaging operation, and the like are mounted. The circuit board 32 is fixed to the exterior 12 on the back side of the digital camera 1 with screws 34 together with the structural member 30 while facing the back side of the taking lens 3. In addition, as a fixing method, you may use not only a screw but a fitting member. The CCD 22 and the circuit board 32 are electrically connected by a flexible circuit board 31. The flexible circuit board 31 is a printed board that is flexible and can be greatly deformed, and has a structure in which a conductive foil such as copper is formed on a film-like insulator such as polyimide. One end of the flexible circuit board 31 is substantially U-shaped, and is arranged so as to sandwich the support portion 30a of the structural member 30 inside the U-shape so as not to contact the support portion 30a. This is because the structural member 30 is formed of sheet metal as will be described later, and is connected to the ground pattern 32a of the circuit board 32, so that there is a risk of causing a short circuit accident when the circuit board 32 comes into contact with the structural member 30. It is. Further, a plurality of terminals 31a are provided on the surface of the substantially U-shaped inner portion, and appropriate terminals 22b of the CCD 22 are soldered to the respective terminals 31a. On the other hand, a connector 31b is attached to the other end, and this connector 31b is connected to the connector 33 mounted on the circuit board 32 by bending the flexible circuit board 31 so as to approach the surface of the circuit board 32. ing. As a result, power can be supplied from the circuit board 32 to the CCD 22, and an imaging signal output from the CCD 22 can be transmitted to the circuit board 32.

  The structural member 30 includes a flat plate-shaped support portion 30a that supports the CCD 22 from the back surface thereof so as to be separated from the circuit board 32, a side wall 30b that protrudes from the support portion 30a so as to face the side surface of the CCD 22, and a support portion 30a. And a holding portion 30c for holding the support portion 30a in front of the circuit board 32 so that the CCD 22 is in a predetermined position. Further, the structural member 30 projects from one end of the holding portion 30c toward the outside along the circuit board 32, and has an attachment part 30d having a screw hole for attaching the structural member 30 to the circuit board 32, and an attachment part 30d. And a cooling unit 30e which is substantially parallel to the surface of the exterior 12 on the left side of the camera where the vent hole 11 is located at a position close to the vent hole 11. These are integrally formed of sheet metal, and have a structure in which heat generated in the CCD 22 can be absorbed by the support portion 30a and the side wall 30b and conducted to the cooling portion 30e. Further, a silicon sheet 35 is disposed between the support portion 30a and the back surface of the CCD 22 to improve the efficiency of heat conduction from the CCD 22 to the structural member 30. In the assembly process, the position of the CCD 22 in the optical axis L direction can be adjusted by adjusting the thickness of the silicon sheet 35, so that the assembly accuracy can be improved. Even if this silicon sheet 35 is not used, there is no problem in the heat conduction itself from the CCD 22 to the support portion 30a.

  The side wall 30 b can absorb heat generated from the side surface of the CCD 25. Furthermore, as will be described later, it also serves as a shield against the electromagnetic radiation of the CCD 22 together with the support portion 30a. In the present embodiment, the side wall 30b is provided only at a position facing the short side of the CCD 22. However, the side wall 30b may be provided at a position facing the long side to cover the four sides of the CCD 22.

  The attachment portion 30d is attached to a ground pattern 32a provided on the surface of the circuit board 32 by screws 34, and electrically connects the entire structural member 30 to the ground pattern 32a. The ground pattern 32a is electrically connected to the inner ground layer of the circuit board 32 through the through hole 32b. Therefore, the structural member 30 serves as a magnetic shield, and the electromagnetic radiation of the CCD 22 can be reduced.

  Since the cooling unit 30e is exposed to the outside air through the vent hole 11, the cooling unit 30e is always maintained at a lower temperature than the other parts of the structural member 30. Therefore, the heat of the CCD 22 absorbed by the support part 30a and the side wall 30b is conducted to the low-temperature cooling part 30e to be radiated. Further, since the attachment portion 30d absorbs part of the heat generated in the circuit board 32, this heat can also be radiated by the cooling portion 30e.

  Next, the operation of this embodiment will be described. When the mode switch 6 is in the shooting mode, the operation control unit 27 starts to control the shooting operation by fully pressing the release switch 5. The subject light captured through the photographing lens 3 is received by the CCD 22 along the optical axis L and converted into an imaging signal. The imaging signal is transmitted to the circuit board 32 via the flexible circuit board 31, is subjected to predetermined processing by the operation control unit 27 and the like, and is recorded on the memory card 10 as an image file. The CCD 22 generates a lot of heat along with this photographing operation. In particular, when the number of pixels of the CCD 22 is large or when high-speed continuous shooting is performed, extremely high heat is generated. This heat is conducted through the silicon sheet 35 to the support portion 30a or to the side wall 30b. Further, this heat is conducted to the cooling unit 30e maintained at a low temperature by the outside air taken in from the vent hole 11, and is radiated. Moreover, since the structural member 30 is electrically connected to the ground pattern 32a of the circuit board 32, the electromagnetic radiation of the CCD 22 is reduced by using the support portion 30a and the side wall 30b as a shield.

  In this way, in the present embodiment, the CCD 22 is efficiently cooled, and the electromagnetic radiation is also reduced. In the embodiment as described above, the structural member 30 is formed of a heat radiating ceramic, and heat dissipation can be enhanced by the effect of radiant heat. However, in this case, the electromagnetic radiation of the CCD 22 is suppressed by the characteristics of the thermal radiation ceramic itself without electrically connecting the structural member 30 to the ground pattern 32a. The silicon sheet 35 need not be used in particular.

  Next, a second embodiment shown in FIG. 7 will be described. Here, parts having the same functions as those of the previous embodiment described in FIG. 6 are denoted by the same reference numerals, and only differences will be described. In the present embodiment, a flat plate-shaped heat dissipating ceramic 36 having a larger area than the back surface of the CCD 22 is sandwiched between the CCD 22 and the support plate 30a. Further, in order to increase the thermal conductivity, the CCD 22 and the heat dissipating ceramic 36 and the silicon sheet 35 are disposed between the heat dissipating ceramic 36 and the support plate 30a. As a result, heat from the back surface of the CCD 22 is conducted to the heat dissipating ceramic 36 and is dissipated as radiant heat at a portion not overlapping the bottom surface of the CCD 22, so that heat dissipation can be improved. The heat that could not be dissipated in the heat dissipating ceramic 36 is dissipated in the cooling unit 30e by the structural member 30 as described above. Even if the silicon sheet 35 is not used, there is no problem in the heat conduction itself from the CCD 22 to the support portion 30a.

  Next, an embodiment obtained by modifying the second embodiment shown in FIGS. 8 and 9 will be described. Here, parts having the same functions as those of the previous embodiment described in FIG. 7 are denoted by the same reference numerals, and only differences will be described. In the present embodiment, the structural member 37 does not contribute to the cooling of the CCD 22 and is cooled only by the heat radiating ceramic 38.

  The structural member 37 is composed of two members having the same shape. Each member holds the support portion 37a in front of the circuit board 32 so that the CCD 22 is located at a predetermined position connected to one end of the support portion 37a and the support portion 37a that supports the flat plate-like heat-dissipating ceramic 38 from the back side. It has a holding part 37b and an attachment part 37c provided with a screw hole for attaching the structural member 37 to the circuit board 32 so as to project outward from the holding part 37b along the circuit board 32. Has been. Here, the structural member 37 and the circuit board 32 are insulated. The two members are attached to the circuit board 32 with screws 34 so that the tips of the support portions 37a face each other, and the heat dissipating ceramics 38 are supported on the front surfaces of the two support portions 37a. For this reason, the back surface of the heat dissipating ceramic 38 sandwiched between the two support portions 37a is exposed inside the camera. The CCD 22 is supported on the front surface of the heat dissipating ceramic 38 via a silicon sheet 35. Since the heat dissipating ceramic 38 has a larger area than the CCD 22, the front portion that does not overlap the CCD 22 is exposed inside the camera. Therefore, the heat dissipating ceramic 38 can cool the CCD 22 by dissipating heat from the front and back surfaces.

  The embodiment described so far has been about a digital camera, but the present invention is not limited to this, and the present invention is applied to any electronic device that uses an image sensor such as a camera-equipped mobile phone or a video camera. be able to.

It is a front perspective view showing a digital camera of the present invention. It is a back perspective view showing a digital camera of the present invention. It is a cross section of the exterior in the vicinity of the ventilation hole. It is an electrical configuration of a digital camera. This is a cooling structure of a CCD. It is a cross section of the horizontal direction of the cooling structure of CCD. It is a cross section of the horizontal direction of the cooling structure of CCD (2nd embodiment). It is a cross section of the horizontal direction of the cooling structure of CCD (embodiment which changed 2nd embodiment). It is an upper view of the cooling structure of CCD (embodiment which changed 2nd embodiment).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Digital camera 2 Flash device 3 Shooting lens 4 Power switch 5 Release switch 6 Mode switch 7 Operation key 8 LCD
9 Memory card slot 10 Memory card 11 Ventilation hole 12 Exterior 22 CCD
22a Cover glass 22b Terminal 30 Structural member 30a Support part 30b Side wall 30c Holding part 30d Mounting part 30e Cooling part 31 Flexible circuit board 31a Terminal 31b Connector part 32 Circuit board 32a Ground pattern 32b Through hole 33 Connector 34 Screw 35 Silicon sheet 36 Heat dissipation Ceramic 37 Structural member 37a Support portion 37b Side wall 37c Mounting portion 38 Heat dissipating ceramic

Claims (10)

A photographic lens, an image sensor that converts subject light incident from the photographic lens into an electrical signal, and a circuit board that is electrically connected to the image sensor and is disposed facing the back surface of the photographic lens. In digital cameras,
Provided with a structural member integrally formed with a sheet metal, attached to the circuit board, supporting the imaging element from its back so as to be separated from the circuit board, and fixing it at a predetermined position behind the photographing lens;
A digital camera characterized in that a part of the structural member approaches a vent hole provided in an exterior of the camera to cool the imaging device.   The digital camera according to claim 1, wherein the structural member is electrically connected to a ground pattern of the circuit board simultaneously with being attached to the circuit board.   The digital camera according to claim 2, wherein the structural member has a side wall facing a side surface of the imaging element.   The digital camera according to claim 1, further comprising a silicon sheet between a back surface of the image sensor and the structural member.   4. The digital device according to claim 1, wherein a flat plate-shaped heat-dissipating ceramic having a larger area than the back surface of the image sensor is sandwiched between the back surface of the image sensor and the structural member. camera.   6. The digital camera according to claim 5, further comprising a silicon sheet between the image sensor and the heat dissipating ceramic, or between the heat dissipating ceramic and the structural member. A photographic lens, an image sensor that converts subject light incident from the photographic lens into an electrical signal, and a circuit board that is electrically connected to the image sensor and is disposed facing the back surface of the photographic lens. In digital cameras,
Provided with a structural member integrally formed of a heat-dissipating ceramic that is attached to the circuit board, supports the imaging element from the back so as to be separated from the circuit board, and fixes the imaging element to a predetermined position behind the photographing lens. ,
A digital camera characterized in that a part of the structural member approaches a vent hole provided in an exterior of the camera to cool the imaging device.   The digital camera according to claim 7, wherein the structural member has a side wall facing a side surface of the imaging element.   The digital camera according to claim 1, wherein the air hole is formed obliquely with respect to a surface of the exterior.   9. The digital camera according to claim 1, wherein a cover that covers the vent hole from the outside is provided on the exterior.

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