JP2008283358A - Imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging apparatus wherein a holding mechanism of an optical filter, etc. is further thinned. <P>SOLUTION: A CCD plate 24 is put on a protection glass 23 of a CCD 22; a CCD mask 26, an optical LPF 27, and an optical LPF cover 28 are successively laminated on the CCD plate 24; and the CCD plate 24 and the optical LPF cover 28 are clamped by a screw 29 to make a unit, and the position and inclination of these components are adjusted as the unit. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an imaging apparatus, and more particularly to an imaging apparatus characterized by a technique for fixing an imaging element in a lens barrel.

  2. Description of the Related Art Electronic still cameras, so-called digital cameras, that convert an object image formed by a photographing optical system into an electrical signal using an image sensor such as a CCD or a CMOS have become widespread. Some of these image sensors are sensitive to infrared light that is invisible to the human eye. In order to prevent image quality degradation due to infrared light, an infrared cut filter is placed inside the photographic optical system. There is an imaging device.

  The following imaging devices are also known in order to prevent image quality degradation due to false colors or moire that occurs when a subject including a sampling frequency determined by the pixel pitch of the imaging element is imaged. In other words, the imaging apparatus has an optical low-pass filter made of crystal exhibiting a birefringence phenomenon arranged in front of the subject side of the imaging element.

  In order to hold these infrared cut filters and / or optical low-pass filters (hereinafter referred to as optical filters), the following structures have been proposed. That is, it is a structure in which the optical filters are fitted and fixed to a ground plate having an opening through which the photographing light flux passes and a recess for positioning the optical filters without greatly deviating.

  By the way, when dust adheres to the surface of the image sensor, the dust portion does not receive light, so that there is a problem that the shadow of the dust enters the subject image and the shadow of the dust appears in the photographed image. Furthermore, the image sensor is normally located inside the photographing lens, and the user cannot clean the image sensor. Therefore, in order to prevent the shadow of the dust from appearing in the photographed image, it is necessary to have a structure that prevents the dust from attaching to the image sensor. Therefore, the front surface of the image sensor is usually covered with a protective glass.

  However, when the dust is large, the dust may appear in the image even if the protective glass surface has dust. Therefore, there is an image pickup apparatus that prevents dust from adhering to the surface of the protective glass by forming a sealed space between the optical filters and the protective glass.

  Furthermore, a mechanism for finely adjusting the position and orientation of the imaging surface may be required to absorb manufacturing errors in the photographic optical system. In addition, improvement in assemblability of optical filters and image sensors is always required for reducing assembly costs. In addition, in order to improve the portability of the imaging apparatus, it is better that the thickness of the optical system in the optical axis direction is thinner.

  In order to reduce the thickness of the optical system occupied by the structure between the protective glass and the optical filters in the optical axis direction, the imaging device and the optical filters are held in the lens barrel. Various proposals have been made for mechanisms.

For example, according to Patent Document 1, a low-pass filter holder made of a thin plate-like metal member that holds optical filters is arranged to reduce the thickness in the optical axis direction. According to Patent Document 2, the optical filter and the image pickup device are held by bonding and fixing.
JP 2006-67356 A JP 2005-12334 A

  However, in the technique described in Patent Document 1, since the CCD plate for holding the image sensor is disposed on the back surface of the image sensor, the thickness in the optical axis direction is increased by the thickness of the CCD plate.

  Moreover, in the technique of the said patent document 2, although optical filters and an image pick-up element are adhere | attached, since the optical filters had to be hold | maintained until an adhesive agent hardened | cured, the assembly property was bad. Further, since separation is difficult, if either the optical filter or the image sensor is damaged, the non-damaged part is also damaged and must be discarded. Further, since the CCD plate for holding the image sensor is arranged on the back surface of the image sensor as in Patent Document 1, the thickness in the optical axis direction is increased by the thickness of the CCD plate.

  In addition, in both Patent Document 1 and Patent Document 2, the position of the imaging surface in the optical axis direction and the inclination with respect to the optical axis cannot be adjusted.

  An object of the present invention is to provide an imaging device that can further reduce the thickness of a holding mechanism for optical filters. In addition, an object of the present invention is to provide an imaging apparatus that can improve the assemblability of the optical filters and the image sensor and can easily separate the optical filters and the image sensor. In addition, an object of the present invention is to provide an imaging apparatus capable of adjusting the position of the imaging element in the optical axis direction and the inclination with respect to the optical axis.

  In order to achieve the above object, an invention according to claim 1 is directed to an image sensor that converts a subject image that has passed through an imaging optical system into an electrical signal, an optical element through which a subject luminous flux passes, the image sensor, and the optical element. A holding member that holds the imaging element, and an elastic member that holds the optical element between the holding member. An image pickup apparatus comprising: a member, wherein the elastic member and the holding member are fastened to constitute an image pickup element unit.

  As described above, according to the present invention, it is possible to provide an imaging apparatus that can further reduce the thickness of a holding mechanism for optical filters. In addition, the assemblability of the optical filter and the image sensor can be improved, and the optical filter and the image sensor can be easily separated. Further, the position of the image sensor in the optical axis direction and the inclination with respect to the optical axis can be adjusted.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is an external perspective view of a retracted state of a digital camera as an imaging apparatus according to an embodiment of the present invention.

  In FIG. 1, the digital camera includes a photographic lens 1, a power button 2, a mode dial 3, and a release button 4.

  The photographic lens 1 is in a retracted state, which is a state for storage without being used for photographing when the power is off. By operating the power button 2, the digital camera can be turned on. Further, the user can select a shooting mode by operating the mode dial 3.

  FIG. 2 is an external perspective view of a shooting state in the digital camera as the imaging device according to the embodiment of the present invention.

  In FIG. 2, the first group holder 11 and the first group guide cylinder 21 are shown. In the photographing mode state, the subject can be imaged through the photographing lens 1 by pressing the release button 4.

  FIG. 3 is a cross-sectional view of the retracted state of the digital camera as the imaging apparatus according to the embodiment of the present invention.

  The configuration will be described below.

  In FIG. 3, the first group lens 10 is held by a group holder 11. Similarly, the second group lens 12 is held by the second group holder 13, the third group lens 14 is held by the third group holder 15, and the fourth group lens 16 is held by the fourth group holder 17.

  The cam ring 18 has a cylindrical shape and has a cam groove that displaces the second group holder 13 and the third group holder 15 in the optical axis direction on the inner surface, although not shown. Cam follower pins are implanted in the second group holder 13 and the third group holder 15, and are cam-engaged with cam grooves on the inner surface of the cam ring 18. Further, the outer surface of the cam ring 18 has a cam groove for displacing the first group holder 11 in the optical axis direction, and a cam follower pin implanted in the first group holder 11 is cam-engaged with the cam groove.

  The fixed cylinder 19 has a cam groove for extending the cam ring 18 in the optical axis direction on the inner surface thereof. The drive ring 20 is a cylindrical member that rotates around the optical axis by a drive force from a drive source when the digital camera is powered on and shifted to a shooting mode. The cam ring 18 is engaged with the drive ring 20 and rotates with the rotation of the drive ring 20. At that time, the cam ring 18 advances and retreats in the optical axis direction while rotating following the cam groove of the fixed cylinder 19.

  The first group guide cylinder 21 is a component that appears on the exterior and has a role of supporting the first group holder 11 so as to be able to advance and retreat in the optical axis direction and hiding a gap formed between the first group holder 11 and the fixed cylinder 19 when the photographing lens 1 is extended. is there.

  The fourth group lens 16 is a so-called focusing lens that has a function of moving back and forth in the optical axis direction by a screw feed mechanism in accordance with the subject distance and positioning the subject in focus on the imaging surface.

  In FIG. 3, the photographic lens 1 is in the retracted state, and the fourth lens group 16 has moved to the position closest to the imaging surface in order to shorten the length of the lens barrel when retracted.

  A subject image formed through an imaging optical system including the first group lens 10, the second group lens 12, the third group lens 14, and the fourth group lens 16 is converted into an electrical signal by the CCD 22 which is an image sensor. The A protective glass 23 for protecting the CCD 22 is fixed to the CCD 22 on the front side on the subject side (the left side in the drawing, the front side on the imaging optical system). Further, a flexible printed circuit board (not shown) serving as an electrical wiring to the CCD 22 is connected to the back surface of the CCD 22.

  The CCD plate (holding member) 24 is a component made of a metal plate and is placed on the protective glass 23 so as to be in contact therewith, and in this state, is bonded and fixed to the CCD 22. Then, the CCD plate 24 is fastened to a predetermined position of a CCD holder (image sensor holder) 25 with screws.

  A CCD mask 26 and an optical LPF (optical LOW PASS FILTER) (optical element) 27 are sequentially stacked on the front side of the CCD plate 24 on the subject side. An LPF cover 28 is arranged on the front side of the optical LPF 27 on the subject side, and the LPF cover 28 is fixed to the CCD plate 24 with screws 29 described later. Next, the configuration around the CCD 22 will be described in more detail with reference to FIGS.

  FIG. 4 is an exploded perspective view of parts around the CCD in FIG. FIG. 5 is a cross-sectional view of components around the CCD in FIG.

  The CCD plate 24 is provided with an opening 24A through which a subject light beam passes. Further, an adhesive hole 24B is provided, and an adhesive 30 is applied in the adhesive hole 24B as shown in FIG. 5, and the CCD plate 24 is adhesively fixed to the CCD 22.

  A CCD mask 26 is disposed in contact with the front surface of the CCD plate 24 on the subject side without any gap. However, the CCD mask 26 prevents rays other than the subject image from entering the imaging surface and becoming a ghost, and may be unnecessary depending on the photographing optical system.

  An optical LPF 27 is arranged in close contact with the CCD mask 26 in front of the subject side of the CCD mask 26. By arranging the components in this order, the space between the protective glass 23 and the optical LPF 27 is sealed by the CCD plate 24, and dust does not adhere to the surface of the protective glass 23. It is possible to prevent the shadows of the waste from being reflected. In the case of a photographing optical system that does not require the CCD mask 26, the optical LPF 27 is directly disposed on the front side of the subject side of the CCD plate 24.

  By the way, the CCD plate 24 is provided with a positioning dowel 24C for determining the installation position of the optical LPF 27 according to its outer shape, and the optical LPF 27 is arranged by using the positioning dowel 24C. The CCD mask 26 has a hole that fits into the positioning dowel 24C, and the position of the CCD mask 26 with respect to the CCD 22 can be determined by fitting the hole with the positioning dowel 24C.

  In the present embodiment, the optical element located on the subject-side front surface of the protective glass 23 is the optical LPF 27, but it may be an infrared cut filter or a laminated part of an infrared cut filter and an optical LPF. Furthermore, it may be a parallel flat glass having no filter action or an optical lens having power.

  The LPF cover 28 disposed on the front surface of the optical LPF 27 is made of a thin metal plate (elastic member). The LPF cover 28 is painted or plated with a color having a low light reflectance such as black to prevent reflection. The CCD plate 24 and the LPF cover 28 are fastened by the screws 29.

  As a result, the CCD 22, CCD plate 24, flexible printed circuit board (not shown), CCD mask 26, optical LPF 27, and LPF cover 28 are integrated. Hereinafter, this integrated component is referred to as a CCD unit (imaging device unit).

  Since the CCD unit can be disassembled into individual parts by removing the screws 29, for example, when dust is contained in the sealed space or the surface of the protective glass 23 is dirty, the CCD unit is disassembled. Can remove dust or clean the surface.

  Since the LPF cover 28 is made of a thin metal plate as described above, for example, even when the optical LPF 27 having a large thickness is incorporated due to a manufacturing error, the LPF cover 28 is elastically deformed and excessive pressure is applied to the optical LPF 27. Will not be added.

  Further, as apparent from FIG. 5, the CCD plate 24 is not disposed on the back surface of the CCD 22 (the surface opposite to the front surface on the object side, the right side surface in the figure). Further, since the optical LPF 27 is held by the LPF cover 28 made of a thin metal plate, it is possible to reduce the thickness of the CCD unit in the optical axis direction.

  The CCD unit is fastened to the CCD holder 25 with screws. A fixed cylinder 19 is fastened to the CCD holder 25, and the CCD holder 25 is fastened to the digital camera body. Since the LPF cover 28 made of a thin metal plate is disposed on the most object side of the CCD unit, as shown in FIG. 3, the distance between the fourth group lens 16 and the optical LPF 27 can be reduced.

  FIG. 6 is an exploded perspective view for explaining the mounting structure of the CCD unit and the CCD holder in FIG.

  In FIG. 6, when assembling the CCD unit and the CCD holder, first, the three compression springs 31 are respectively inserted into the bottomed holes 25 </ b> A of the CCD holder 25. Next, the CCD unit is incorporated into the CCD holder 25 using the positioning dowel 25B of the CCD holder 25 as a guide. At this time, the compression spring 31 abuts on the CCD plate 24 to urge the CCD unit in a direction away from the CCD holder 25.

  In this state, the CCD unit follows the CCD screw 32 by screwing the CCD screw 32 into the CCD holder 25 from the CCD plate 24 side of the CCD unit. Thereby, the position of the CCD unit in the optical axis direction can be finely adjusted by changing the screwing amount of the CCD screw 32. Further, by loosely fitting the positioning dowel 25B to the CCD unit, the amount of screwing of each of the three CCD screws 32 can be changed to finely adjust the inclination of the CCD unit.

It is an external appearance perspective view of the retracted state in the digital camera as an imaging device concerning an embodiment of the invention. 1 is an external perspective view of a shooting state in a digital camera as an imaging apparatus according to an embodiment of the present invention. It is sectional drawing of the retracted state in the digital camera as an imaging device which concerns on embodiment of this invention. FIG. 4 is an exploded perspective view of components around the CCD in FIG. 3. FIG. 4 is a cross-sectional view of components around the CCD in FIG. 3. It is a disassembled perspective view for demonstrating the attachment structure of the CCD unit and CCD holder in FIG.

Explanation of symbols

1. Shooting lens (components for imaging optical system)
2 Power button 3 Mode dial 4 Release button 10 First lens group (components for imaging optical system)
11 1 group holder 12 2nd group lens (imaging optical system component)
13 Second group holder 14 Third group lens (imaging optical system component)
15 3 group holder 16 4th group lens (imaging optical system component)
17 Fourth group holder 18 Cam ring 19 Fixed cylinder 20 Drive ring 21 First group guide cylinder 22 CCD (imaging device)
23 Protective glass 24 CCD plate (holding member)
24A Opening 24B Bonding hole 24C Positioning dowel 25 CCD holder (image sensor holder)
25A Bottomed hole 25B Positioning dowel 26 CCD mask 27 Optical LPF (optical element)
28 LPF cover (elastic member)
29 Screw 30 Adhesive 31 Compression spring 32 CCD screw

Claims (3)

An image sensor that converts a subject image that has passed through the imaging optical system into an electrical signal;
An optical element through which the subject luminous flux passes;
A holding member that is disposed between the imaging element and the optical element, has an opening through which a subject light flux passes, and holds the imaging element;
An elastic member arranged to hold the optical element between the holding member and the optical element;
An image pickup apparatus comprising an image pickup device unit configured by fastening the elastic member and the holding member.   The imaging apparatus according to claim 1, wherein a protective glass is provided on a front surface of the imaging element on the imaging optical system side.   The imaging apparatus according to claim 1, wherein the imaging element unit is attached to the imaging element holder by a compression spring.

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