JP2006140706A - Electronic camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic camera which can easily be manufactured and enables the cost thereof to be prevented from increasing while securing the degree of freedom of design. <P>SOLUTION: A camera body 2 of the electronic camera 1 includes a mount portion 3, a mirror box 4, a shutter unit 5, and a CCD package 6 which are arranged in order along an optical axis Ax and is further equipped with a birefringent plate 16 arranged between a photographic lens 7 and a main mirror 9, a phase plate 17 arranged in the space between the main mirror 9 and shutter unit 5, and a birefringent plate 18 and an infrared cutting filter 19 arranged in the space between the shutter unit 5 and CCD package 6. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electronic camera.

  2. Description of the Related Art Conventionally, in an electronic camera that acquires image data of a subject using a CCD or the like, a CCD cover is provided on the front surface of the imaging unit 50 as shown in FIG. 5 in order to prevent false color (moire) from occurring in the image data of the subject. An optical low-pass filter 52 is disposed through the glass 51. The optical low-pass filter 52 reduces the spatial frequency component close to the sampling spatial frequency determined by the CCD pixel interval on the CCD imaging surface 53, and therefore, an infrared absorbing glass and a birefringent plate disposed in order from the imaging unit 50 side. And a phase plate and a birefringent plate, that is, a four-layer laminate.

  In a single-lens reflex electronic camera having a rotatable main mirror between a photographing lens and an image pickup unit 50, it is necessary to dispose a shutter unit between the main mirror and the image pickup unit 50, and thereby an optical low-pass. The filter 52 is disposed between the shutter unit and the imaging unit 50.

  However, since the size of the space between the shutter unit and the imaging unit 50 is limited, for example, a square separation type optical low-pass filter 52 having a lamination thickness of about 3.1 to 3.3 mm is provided. There is a problem that it is not easy to arrange in the space and the degree of freedom in design is low. Therefore, in recent years, the CCD cover glass 51 has been abolished and a birefringent plate is directly attached to the front surface of the imaging unit 50 to reduce the number of low-pass filters and reduce the thickness thereof (for example, In other words, the thickness of the birefringent plate is reduced by using lithium niobate instead of quartz as the material of the birefringent plate.

  However, when a birefringent plate is directly attached to the front surface of the imaging unit 50, the birefringent plate is handled integrally with the imaging unit 50, so that the birefringent plate is easily damaged in the production process of the electronic camera. There is a problem that it is difficult to manufacture.

  Further, the optical low-pass filter 52 has a surface defect level lower than that of a simple single glass because of pasting or coating.

  Further, when lithium niobate is used instead of quartz as the material for the birefringent plate, there is a problem that the manufacturing cost increases because lithium niobate is very expensive.

JP 2000-114502 A

  An object of the present invention is to provide an electronic camera that can be easily manufactured and can suppress an increase in cost while ensuring a degree of freedom in design.

Such an object is achieved by the present inventions (1) to (12) below.
(1) An imaging lens that is sequentially arranged along the optical axis, a mirror that is rotatably installed, a shutter unit, and an imaging unit that captures an electronic image, and includes at least two layers having different optical characteristics An electronic camera provided with an optical filter,
Each layer is separated into at least two spaces among a space between the photographing lens and the mirror, a space between the mirror and the shutter unit, and a space between the shutter unit and the imaging unit. An electronic camera characterized by being arranged.

  As a result, even if the space between the shutter unit and the imaging unit is limited, an optical filter with a large stacking thickness can be accommodated in the electronic camera, and the degree of freedom in designing the electronic camera is ensured. However, an electronic camera can be easily manufactured, and an increase in cost of the electronic camera can be suppressed.

  (2) The electronic camera according to (1), wherein at least one of the layers is disposed in a space between the shutter unit and the imaging unit.

(3) The electronic camera according to (1) or (2), wherein each of the layers is detachable from the electronic camera.
Thereby, the cleaning operation (maintenance) of the electronic camera can be easily performed.

(4) The electronic camera according to any one of (1) to (3), wherein the optical filter is an optical low-pass filter.
Thereby, the high frequency component which degrades an image can be optically suppressed reliably.

(5) The electronic camera according to any one of (1) to (4), wherein the optical filter includes at least one of a birefringent layer, a phase layer, and an infrared cut filter.
Thereby, a low-pass filter characteristic can be obtained reliably.

(6) The electronic camera according to (5), wherein the phase layer is disposed in a space between the mirror and the shutter unit or in a space between the shutter unit and the imaging unit.
Thereby, the freedom degree of design of an electronic camera can be improved more easily.

(7) The electronic camera according to (5) or (6), wherein each of the birefringent layer and the phase layer is made of quartz.
Thereby, an increase in the cost of the electronic camera can be more reliably suppressed.

(8) The electronic camera according to any one of (1) to (7), wherein the optical filter is a square separation type filter.
As a result, a high-quality image can be taken without causing moire.

(9) It further comprises a mirror box that houses the mirror,
The electronic camera according to any one of (1) to (8), wherein a space between the photographing lens and the mirror and a space between the mirror and the shutter unit are provided in the mirror case. .

  Thereby, an optical filter with a large laminated thickness can be more reliably accommodated in the electronic camera.

(10) The layer disposed in the space between the photographic lens and the mirror and the layer disposed in the space between the mirror and the shutter unit are each in the lens box via a frame. The electronic camera according to (9), which is fixed to the camera.
Thereby, the cleaning operation (maintenance) of the electronic camera can be easily performed.

  (11) The electronic camera according to (10), wherein a dustproof member is provided between the frame and the lens box.

  Thereby, it is possible to prevent dust from entering the shutter unit and the imaging unit.

(12) The electronic camera according to any one of (1) to (11), wherein each of the layers includes an optical characteristic plate that exhibits one optical characteristic.
Thereby, each layer can be handled more easily.

  According to the present invention, a plurality of layers (optical characteristic plates) of the optical filter are provided in a space between the photographing lens and the mirror, a space between the mirror and the shutter unit, and a space between the shutter unit and the imaging unit. By separating and arranging in at least two spaces, there is room in the space between the shutter unit and the imaging unit compared to the case where the optical filter is arranged only in the space between the shutter unit and the imaging unit. For example, an optical filter having a large laminated thickness can be accommodated in an electronic camera without omitting a CCD cover glass or the like. For this reason, it is possible to easily manufacture the electronic camera while suppressing the degree of freedom in designing the electronic camera, and to suppress an increase in the cost of the electronic camera.

Hereinafter, an electronic camera of the present invention will be described in detail based on a preferred embodiment shown in the accompanying drawings.
FIG. 1 is a front view showing a first embodiment of the electronic camera of the present invention, FIG. 2 is a cross-sectional view showing the internal structure of the electronic camera shown in FIG. 1, and FIG. It is a disassembled perspective view which shows the flame | frame to which the optical characteristic board is fixed.

  The electronic camera 1 shown in these drawings is a lens-interchangeable single-lens reflex electronic camera including a camera body 2 and a photographing lens 7 that is detachable from the camera body 2. On the front surface of the camera body 2, a mount portion 3 for detachably attaching the photographing lens 7 is provided.

  The camera body 2 includes a mount unit 3 arranged in order from the front side (left side in FIG. 2) along the optical axis Ax, a housing-like mirror box (mirror box) 4, a shutter unit 5, and a CCD package ( Imaging unit) 6. Since the photographic lens 7 is attached to the mount portion 3, the photographic lens 7 is also arranged along the optical axis Ax in the same manner as the mirror box 4 or the CCD package 6.

  Here, the distance (flange back) L from the mounting surface of the mounting lens 3 to the CCD imaging surface 8 in the CCD package 6 is substantially the same as the distance from the shooting lens mount surface to the shooting film surface in the silver salt camera. It is. Further, the shutter unit 5 and the CCD package 6 are arranged with a predetermined clearance.

  A main mirror (mirror) 9 is provided inside the mirror box 4. The main mirror 9 is installed so as to be rotatable about a rotation shaft 10 provided in the vicinity of the upper end of the main mirror 9. The optical axis extends along the first position shown in FIG. 2 and the upper surface 11 of the inner wall of the mirror box 4. It rotates between a second position (not shown) that is substantially parallel to Ax. The main mirror 9 operates by the driving force of a mirror motor (not shown) driven via a motor driver (not shown).

  When the main mirror 9 is disposed at the first position, most of the luminous flux (subject light) that has passed through the photographing lens 7 and entered the camera body 2 is reflected by the main mirror 9, and the mirror box 4. The light is incident on a focusing screen (not shown) disposed on the upper surface 11 of the inner wall and further a pentaprism (not shown). The light beam reflected by the pentaprism is emitted through an eyepiece lens (not shown). Thereby, the user can observe the imaging state on the focusing screen by the photographing lens 7 through the eyepiece.

  Further, a part of the main mirror 9 is a half mirror, and a part of the light flux from the photographing lens 7 is transmitted through the main mirror 9 and is lowered below by the sub mirror 12 provided on the back side of the main mirror 9. It is reflected and enters an AF sensor (not shown).

  Here, the light beam reflected by the main mirror 9 and incident on the upper surface 11 of the inner wall 11 of the mirror box 4 and further incident on the pentaprism is obtained only from the optical characteristic plate disposed in the first gap space described later. It is the light flux that has passed.

  When the main mirror 9 is disposed at the second position, the main mirror 9 is retracted from the optical path of the light beam from the photographing lens 7, and the light beam from the photographing lens 7 is transmitted by the main mirror 9. The light can enter the shutter unit 5 and the CCD package 6 without being reflected. That is, the light beam from the photographic lens 7 can enter the CCD package 6 through a birefringent plate 16, a phase plate 17, a birefringent plate 18, and an infrared cut filter 19 which will be described later.

  The shutter unit 5 is a so-called focal plane shutter, and is installed so as to face the CCD image plane 8 of the CCD package 6. The shutter unit 5 has a front curtain and a rear curtain, and at the time of exposure, a slit having an arbitrary interval formed between the front curtain and the rear curtain crosses in front of the CCD image plane 8 at a predetermined speed. Is moved to the CCD image plane 8. The shutter unit 5 is driven by a shutter drive circuit (not shown).

  The CCD package 6 has a casing 13 having a rectangular shallow recess, a flat CCD 14 installed in the recess of the casing 13, and a CCD cover glass 15 installed so as to cover the opening of the recess of the casing 13. The left side surface of the CCD 14 in FIG. The CCD package 6 is installed such that its CCD image plane 8 is perpendicular to the optical axis Ax of the photographing lens 7 mounted on the mount unit 3. The optical axis Ax coincides with the center of the imaging area (CCD imaging plane 8) of the CCD package 6.

  In addition, the camera body 2 includes an optical low-pass filter including at least two (four in the present embodiment) layers having different optical characteristics. Each layer of the optical low-pass filter is a birefringent plate (birefringent layer) 16, a phase plate (phase layer) 17, a birefringent plate (birefringent layer) 18 and red, which are optical characteristic plates that exhibit one optical characteristic. An outer cut filter (infrared cut layer) 19 is formed. In this embodiment, the birefringent plate 16, the phase plate 17, the birefringent plate 18, and the infrared cut filter 19 are installed in this order from the front side (left side in FIG. 2) along the optical axis Ax.

  The birefringent plate 16 is disposed in a space between the photographic lens 7 and the main mirror 9 (hereinafter referred to as “first gap space”), and the phase plate 17 is disposed between the main mirror 9 and the shutter unit 5. The birefringent plate 18 and the infrared cut filter 19 are arranged between the shutter unit 5 and the CCD package 6 (hereinafter referred to as “third gap space”). ”). That is, in the present embodiment, the optical characteristic plates are arranged in the first gap space to the third gap space, respectively.

  The constituent materials of the birefringent plate 16, the phase plate 17, and the birefringent plate 18 are not particularly limited, and examples thereof include quartz.

  Moreover, although the constituent material of the infrared cut filter 19 is not specifically limited, For example, the glass (infrared absorption glass) etc. which absorb infrared rays are mentioned.

  By the way, in this embodiment, the optical characteristic plate disposed in the first gap space or the second gap space is fixed to the mirror box 4 via a frame (frame body) described later.

  Specifically, as shown in FIG. 3, for example, a frame 20 in which a metal flat plate is punched out into a frame shape by press molding, and the optical characteristic plate support arranged to be recessed at least on one side of the inner peripheral portion The optical characteristic plate is fixed to the frame 20 by bringing an arbitrary optical characteristic plate of the optical low-pass filter into contact with the optical characteristic plate supporting part 21 and bonding to the frame 20 having the portion 21. Further, the frame 20 to which the optical characteristic plate disposed in the first gap space is fixed is fixed to the frame seating surfaces 22a and 22a of the mirror box 4 with screws 21 and 21 (see FIG. 2). Similarly, the frame 20 to which the optical characteristic plate disposed in the second gap space is fixed is fixed to the frame seating surfaces 22b and 22b of the mirror box 4 by screws 21 and 21.

  Here, a substantially square frame-shaped dustproof seal member (dustproof member) 23 is disposed between each frame 20 and each frame seat surface 22a, 22b. Since the dustproof seal member 23 is disposed so as to surround the opening of the frame 20, it is possible to prevent dust from entering the shutter unit 5 and the CCD package 6. In addition, although the constituent material of the dust-proof seal member 23 is not specifically limited, For example, rubber-type packing, sponge material which collects garbage, etc. are mentioned.

  By fixing an arbitrary optical characteristic plate of the optical low-pass filter to the mirror box 4 with the screw 21 via the frame 20, the optical characteristic plate can be attached to and detached from the mirror box 4, and the electronic camera 1 By detaching the optical characteristic plate during maintenance, for example, it is possible to easily remove dust adhering to the surface of each optical characteristic plate or the CCD imaging surface 8, and maintenance of the electronic camera 1 can be performed. It can be done easily.

  By the way, in an optical low-pass filter, a birefringent plate and a phase plate are usually in contact (bonded) with each other, but a new optical function is not exhibited by the contact between the birefringent plate and the phase plate, and the optical low-pass filter is optical. Therefore, even when the birefringent plate and the phase plate are not bonded to each other, the same function as when the birefringent plate and the phase plate are bonded to each other is exhibited. Accordingly, the birefringent plate 16, the phase plate 17 and the birefringent plate 18 cooperate with each other (integrally) to function as a square separation type optical low-pass filter, and the pixel interval of the CCD 14 from the spatial frequency of the subject light. By reducing the spatial frequency component close to the sampling spatial frequency determined by (2), false color (moire) is prevented from occurring in the image data of the subject. The infrared cut filter 19 removes infrared wavelength components from the subject light from the photographing lens 7 and prevents the CCD package 6 from receiving infrared light that is invisible to human eyes.

  The distance in the direction along the optical axis Ax of the first gap space and the distance in the direction along the optical axis Ax of the second gap space are generally set in the direction along the optical axis Ax of the third gap space. Although it is smaller than the distance, for example, in a square separation type optical low-pass filter having a separation width of about 6 μm to 8 μm (for example, about 7 μm), the thickness of the birefringent plate made of quartz is about 1 mm to 1.4 mm. (For example, about 1.2 mm), the thickness of the phase plate that is also made of quartz is about 0.3 mm to 1.2 mm (for example, about 0.4 mm), and the thickness of the infrared cut filter is It is about 0.3 mm to 0.5 mm. Therefore, if the birefringent plate, the phase plate, or the infrared cut filter is one or two, it can be arranged in the first gap space or the second gap space. In this embodiment, as described above, Since the birefringent plate 16 is arranged in the first gap space and the phase plate 17 is arranged in the second gap space, if the birefringent plate 18 and the infrared cut filter 19 are arranged in the third gap space. In this manner, the camera body 2 can accommodate the square separation type optical low-pass filter without expanding the third gap space.

  In the camera body 2, the optical characteristic plates of the optical low-pass filter are arranged in the order of the birefringent plate 16, the phase plate 17, the birefringent plate 18, and the infrared cut filter 19. Without being limited thereto, any arrangement order may be employed as long as the phase plate is sandwiched between two birefringent plates, for example, the infrared cut filter may be disposed on the most front side, An infrared cut filter may be disposed between the two birefringent plates.

  As described above, according to the electronic camera 1, the birefringent plate 16 is disposed in the first gap space and the phase plate 17 is disposed in the second gap space. Only the birefringent plate 18 and the infrared cut filter 19 are arranged. Thereby, even if the size of the third gap space is limited, for example, a square separation type optical low-pass filter can be accommodated in the electronic camera 1 without omitting the CCD cover glass 15 and the like. The electronic camera 1 can be easily manufactured while ensuring the degree of freedom of design of the camera 1, and an increase in the cost of the electronic camera 1 can be suppressed.

Next, a second embodiment of the electronic camera of the present invention will be described.
FIG. 4 is a cross-sectional view showing the internal structure of the electronic camera of the second embodiment.

  Hereinafter, the electronic camera 1 according to the second embodiment will be described focusing on the differences from the first embodiment described above, and description of similar matters will be omitted.

  The electronic camera 1 of the second embodiment is the same as that of the first embodiment described above except that the arrangement positions of the optical characteristic plates of the optical low-pass filter are different. That is, in the present embodiment, the optical characteristic plates are arranged in the third gap space and one of the first and second gap spaces, respectively.

  As shown in FIG. 4, in the electronic camera 1 of the second embodiment, the birefringent plate 16 is disposed in the second gap space, and the phase plate 17, the birefringent plate 18 and the infrared cut filter 19 are in the third gap. Arranged in space. The birefringent plate 16 may be disposed in the first gap space.

  According to the electronic camera 1 of the second embodiment, the same effects as those of the electronic camera 1 of the first embodiment described above can be obtained. In the electronic camera 1, maintenance can be performed more easily.

  As mentioned above, although the electronic camera of the present invention has been described based on the illustrated embodiment, the present invention is not limited to this, and the configuration of each part is replaced with an arbitrary configuration having the same function. be able to. In addition, any other component may be added to the present invention.

  In the first embodiment described above, the birefringent plate 16, the phase plate 17, and the birefringent plate 18 are disposed in the first gap space, the second gap space, and the third gap space, respectively. The birefringent plate 16 is arranged in the first or second gap space, and the phase plate 17 and the birefringent plate 18 are arranged in the third gap space. However, the birefringent plate 16 and the phase plate 17 in the present invention are used. The combination of the arrangement positions of the birefringent plates 18 is not limited to this. For example, the combination of the arrangement positions is birefringent plate 16 / phase plate 17 / birefringent plate 18 = first gap space / first gap space / second. 2 gap space, birefringence plate 16 / phase plate 17 / birefringence plate 18 = first gap space / first gap space / third gap space, birefringence plate 16 / phase plate 17 / birefringence plate 18 = Second gap space / second gap space / third gap space, and birefringent plate 1 / Phase plate 17 / birefringent plate 18 = may be any of the first interstitial space / second gap space / second gap space. That is, each optical characteristic plate (each layer) may be disposed separately in at least two of the first gap space to the third gap space.

  In the case where each optical characteristic plate is arranged in either the first gap space or the second gap space, it is possible to eliminate the need to arrange the optical low-pass filter in the third gap space. The degree of design freedom can be ensured.

  In the above-described embodiment, the optical low-pass filter accommodated in the electronic camera 1 is a square separation type optical low-pass filter. However, the optical low-pass filter accommodated in the electronic camera 1 is not limited to this, for example, It is a parallelogram optical low-pass filter composed of two birefringent plates and an infrared cut filter, or a two-point separation type optical low-pass filter composed of one birefringent plate and an infrared cut filter. May be.

  Here, it is not limited to the optical low-pass filter type (square separation type, parallelogram type, two-point separation type), and it is preferable to arrange other than infrared absorbing glass in the first gap space.

  As an example, the birefringent plate 16 and the phase plate 17 among the birefringent plate 16, the phase plate 17, and the infrared cut filter 19 that constitute the optical low-pass filter of the (camera-separated) electronic camera 1 of each of the embodiments described above. It is preferable to arrange in the first gap space. The optical characteristic plate disposed in the first gap space is positioned in front of the main mirror 9 (left side in FIG. 2). Therefore, it is necessary for the user to observe the imaging state on the focusing screen by the photographing lens 7 in the first gap space, or the user observes the imaging state on the focusing screen by the photographing lens 7. It is sometimes preferable to arrange an optical characteristic plate that does not hinder. That is, each optical characteristic plate disposed in the second gap space and the third gap space is located at the rear stage (right side in FIG. 2) of the main mirror 9. For this reason, it is preferable to dispose unnecessary optical characteristic plates in the second gap space and the third gap space when the user observes the imaging state on the focusing screen by the photographing lens 7.

  Moreover, in each said embodiment, although the infrared cut filter was used as an infrared absorption member, it is not restricted to this, For example, you may use an infrared absorption coating material etc. In this case, the infrared absorbing coating material is provided on either the front surface or the back surface of each of the other optical characteristic plates.

  Moreover, in each said embodiment, although the birefringent plates 16 and 18 and the phase plate 17 are comprised with quartz, it is not restricted to this, For example, you may comprise with the thin film etc.

It is a front view which shows 1st Embodiment of the electronic camera of this invention. It is a cross-sectional view which shows the internal structure of the electronic camera shown in FIG. It is a disassembled perspective view which shows the optical characteristic board of an optical low-pass filter, and the flame | frame to which the optical characteristic board is fixed. It is a cross-sectional view which shows the internal structure of the electronic camera of 2nd Embodiment. It is sectional drawing which shows the positional relationship of the optical low-pass filter and imaging unit in the conventional electronic camera.

Explanation of symbols

Ax Optical axis 1 Electronic camera 2 Camera body 3 Mount unit 4 Mirror box 5 Shutter unit 6 CCD package 7 Shooting lens 8, 53 CCD imaging surface 9 Main mirror 10 Rotating shaft 11 Inner wall upper surface 12 Sub mirror 13 Casing 14 CCD
15, 51 CCD cover glass 16, 18 Birefringence plate 17 Phase plate 19 Infrared cut filter 20 Frame 21 Screw 22a, 22b Frame seat 23 Dust-proof seal member 50 Imaging unit 52 Optical low-pass filter

Claims (12)

An optical filter including an imaging lens arranged in order along an optical axis, a rotatable mirror, a shutter unit, and an imaging unit that captures an electronic image, and including at least two layers having different optical characteristics An electronic camera comprising:
Each layer is separated into at least two spaces among a space between the photographing lens and the mirror, a space between the mirror and the shutter unit, and a space between the shutter unit and the imaging unit. An electronic camera characterized by being arranged.   The electronic camera according to claim 1, wherein at least one of the layers is disposed in a space between the shutter unit and the imaging unit.   The electronic camera according to claim 1, wherein each of the layers is detachable from the electronic camera.   The electronic camera according to claim 1, wherein the optical filter is an optical low-pass filter.   The electronic camera according to claim 1, wherein the optical filter includes at least one of a birefringent layer, a phase layer, and an infrared cut filter.   The electronic camera according to claim 5, wherein the phase layer is disposed in a space between the mirror and the shutter unit or in a space between the shutter unit and the imaging unit.   The electronic camera according to claim 5 or 6, wherein each of the birefringent layer and the phase layer is made of quartz.   The electronic camera according to claim 1, wherein the optical filter is a square separation type filter. A mirror box for housing the mirror;
The electronic camera according to claim 1, wherein a space between the photographing lens and the mirror and a space between the mirror and the shutter unit are provided in the mirror case.   The layer disposed in the space between the photographic lens and the mirror and the layer disposed in the space between the mirror and the shutter unit are each fixed to the mirror case via a frame. The electronic camera according to claim 9.   The electronic camera according to claim 10, wherein a dustproof member is provided between the frame body and the mirror box. The electronic camera according to claim 1, wherein each of the layers includes an optical characteristic plate that exhibits one optical characteristic.

Images