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Digital Camera Patent Abstract
A cleaning attachment for removing dust stuck to a surface of an
image pickup device in a camera body of a digital camera using an
interchangeable lens capable of being detachably attached to a mount
portion of the camera body, the cleaning attachment includes a mount
portion detachably attached to the mount portion of the camera body;
a facing member facing the surface of the image pickup device; a
radial-air-passage forming surface, formed on a rear surface of
the facing member to extend parallel to the image pickup device,
for forming a radial air passage between the radial-air-passage
forming surface and the image pickup device, the radial air passage
extending orthogonally to an optical axis of the camera; a suction
port formed in the radial-air-passage forming surface; and a suction
device for producing a flow of air into the suction port through
the radial air passage.
Digital Camera Patent Claims
1. A cleaning attachment for removing dust stuck to a front surface
of an image pickup device provided in a camera body of a digital
camera using an interchangeable lens capable of being detachably
attached to a mount portion of said camera body, said cleaning attachment
comprising: a mount portion which is detachably attached to said
mount portion of said camera body; a facing member which faces said
front surface of said image pickup device; a radial-air-passage
forming surface, formed on a rear surface of said facing member
to extend parallel to said front surface of said image pickup device,
for forming a radial air passage between said radial-air-passage
forming surface and said front surface of said image pickup device,
said radial air passage extending orthogonally to an optical axis
of the camera; at least one suction port formed in said radial-air-passage
forming surface; and a suction device, connected to said suction
port, for producing a flow of air into said suction port through
said radial air passage.
2. The cleaning attachment according to claim 1, further comprising
a circumferential frame provided around said facing member, wherein
said facing member comprises an outer-air-passage forming surface,
formed on an outer peripheral surface of said facing member, for
forming an outer air passage between said outer-air-passage forming
surface and an inner surface of said circumferential frame, said
outer air passage being communicatively connected with said radial
air passage.
3. The cleaning attachment according to claim 2, wherein said outer
air passage and said radial air passage are configured so that a
velocity of airflow increases in a direction of flow from said outer
air passage to said radial air passage.
4. The cleaning attachment according to claim 1, wherein said outer-air-passage
forming surface and said radial-air-passage forming surface are
connected to each other via a curved surface.
5. The cleaning attachment according to claim 1, wherein said at
least one suction port is formed in said radial-air-passage forming
surface at a position away from a center of said radial-air-passage
forming surface.
6. The cleaning attachment according to claim 1, further comprising
a connecting body which is detachably attached to said mount portion
of said camera body and supports said facing member.
7. The cleaning attachment according to claim 6, further comprising
a support frame immovable relative to said connecting body, wherein
said facing member is supported by said support frame to be movable
relative to said support frame in a direction to move toward and
away from said front surface of said image pickup device, wherein
said facing member is biased in a direction away from a limit of
movement thereof closest to said front surface of said image pickup
device, and wherein said cleaning attachment further comprises:
a stop mechanism for maintaining a gap between said rear surface
of said facing member and said front surface of said image pickup
device at a constant size when said facing member is moved to said
limit of movement of said facing member.
8. The cleaning attachment according to claim 6, wherein said connecting
body is in the shape of a hood having an open end and a closed end
at opposite ends thereof, respectively, said open end of said hood
being detachably attached to said mount portion of said camera body.
9. The cleaning attachment according to claim 1, further comprising
at least one spacer which projects from said radial-air-passage
forming surface, and comes in contact with a part of said front
surface of said image pickup device which faces the periphery of
an effective imaging area of said image pickup device to form said
radial air passage between said front surface of said image pickup
device and said radial-air-passage forming surface.
10. The cleaning attachment according to claim 1, wherein said
image pickup device comprises: an image pickup element, and an optical
covering element positioned immediately in front of said image pickup
element.
11. The cleaning attachment according to claim 1, wherein said
suction port is formed at a center of said radial-air-passage forming
surface.
12. The cleaning attachment according to claim 2, wherein said
circumferential frame has a rectangular shape in cross section taken
along a plane orthogonal to said optical axis direction.
13. The cleaning attachment according to claim 4, wherein said
connection between said outer-air-passage forming surface and said
radial-air-passage forming surface is chamfered so as to form said
curved surface.
14. The cleaning attachment according to claim 5, wherein said
at least one suction port comprises two suction ports made in said
radial-air-passage forming surface on opposite sides of said center
thereof, respectively.
15. The cleaning attachment according to claim 1, wherein said
digital camera comprises a single-lens-reflex camera.
16. A cleaning attachment for removing dust stuck to a front surface
of an image pickup device provided in a camera body of a digital
camera using an interchangeable lens capable of being detachably
attached to a mount portion of said camera body, said cleaning attachment
comprising: a mount portion which is detachably attached to said
mount portion of said camera body; a facing member which faces said
front surface of said image pickup device; a circumferential frame
provided around said facing member to form a first outer air passage
and a second outer air passage between said circumferential frame
and said facing member on opposite sides of said facing member,
respectively; a radial-air-passage forming surface, formed on a
rear surface of said facing member to extend parallel to said front
surface of said image pickup device, for forming a radial air passage
between said radial-air-passage forming surface and said front surface
of said image pickup device, said radial air passage extending orthogonally
to said optical axis and communicatively connected with each of
said first outer air passage and said second outer air passage;
and a suction device, communicatively connected with said second
outer air passage, for producing a flow of air in a direction of
flow from said first outer air passage to said second outer air
passage through said radial air passage, wherein said first outer
air passage is configured so that the velocity of airflow increases
in a direction of flow from said first outer air passage to said
radial air passage.
17. The cleaning attachment according to claim 16, further comprising
a connecting body which is detachably attached to said mount portion
of said camera body and supports said facing member.
18. The cleaning attachment according to claim 17, further comprising
a support frame immovable relative to said connecting body, wherein
said facing member is supported by said support frame to be movable
relative to said support frame in a direction to move toward and
away from said front surface of said image pickup device wherein
said facing member is biased in a direction to approach said front
surface of said image pickup device, and wherein said cleaning attachment
further comprises: a stop device which moves with said facing member
and separates said radial-air-passage forming surface from said
front surface of said image pickup device by being brought into
contact with said front surface of said image pickup device to form
said radial air passage between said radial-air-passage forming
surface and said front surface of said image pickup device.
19. The cleaning attachment according to claim 17, wherein said
connecting body is in the shape of a hood having an open end and
a closed end at opposite ends thereof, respectively, said open end
of said hood being detachably attached to said mount portion of
said camera body.
20. The cleaning attachment according to claim 16, wherein a connection
between said first outer air passage and said radial air passage
comprises a curved surface, and wherein a connection between said
second outer air passage and said radial air passage comprises a
curved surface.
21. The cleaning attachment according to claim 16, wherein said
image pickup device comprises: an image pickup element, and an optical
covering element positioned immediately in front of said image pickup
element.
22. The cleaning attachment according to claim 16, wherein said
digital camera comprises a single-lens-reflex camera.
Digital Camera Patent Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a cleaning attachment designed
for use in removing dust stuck to a surface of an image pickup device
positioned inside a camera body of a digital camera, wherein the
cleaning attachment is detachably attached to the camera body from
which an interchangeable lens is detached.
[0003] 2. Description of the Prior Art
[0004] A conventional cleaning attachment as described above is
disclosed in, e.g., Japanese Laid-Open Patent Publication (Kokai)
No. 2005-24905. The cleaning attachment disclosed in JLPP No. 2005-24905
is provided with an air blower and an air nozzle positioned in front
of the image pickup device for jetting air generated by the air
blower. This air is directed to an optical low-pass filter installed
immediately in front of the image pickup device from the air nozzle
to remove dust stuck to the front surface of the optical low-pass
filter by the air pressure.
[0005] Since the aforementioned dust is stuck to the optical low-pass
filter by electrostatic or intermolecular force, it is difficult
to remove the dust simply by directing air to the optical low-pass
filter from the air nozzle. Accordingly, the air blower conventionally
needs to be large in size to remove the dust thoroughly from the
optical low-pass filter.
[0006] However, an increase in size of the air blower causes an
increase in size of the cleaning attachment and the production cost
thereof.
SUMMARY OF THE INVENTION
[0007] The present invention provides a cleaning attachment for
removing such dust as mentioned above, wherein the cleaning attachment
can blow air on the dust at a higher pressure than that of the prior
art with no need to increase the size of the air blower.
[0008] According to an aspect of the present invention, a cleaning
attachment is provided, for removing dust stuck to a front surface
of an image pickup device provided in a camera body of a digital
camera using an interchangeable lens capable of being detachably
attached to a mount portion of the camera body, the cleaning attachment
including a mount portion which is detachably attached to the mount
portion of the camera body; a facing member which faces the front
surface of the image pickup device; a radial-air-passage forming
surface, formed on a rear surface of the facing member to extend
parallel to the front surface of the image pickup device, for forming
a radial air passage between the radial-air-passage forming surface
and the front surface of the image pickup device, the radial air
passage extending orthogonally to an optical axis of the camera;
at least one suction port formed in the radial-air-passage forming
surface; and a suction device, connected to the suction port, for
producing a flow of air into the suction port through the radial
air passage.
[0009] It is desirable for the cleaning attachment to include a
circumferential frame provided around the facing member. The facing
member includes an outer-air-passage forming surface, formed on
an outer peripheral surface of the facing member, for forming an
outer air passage between the outer-air-passage forming surface
and an inner surface of the circumferential frame, the outer air
passage being communicatively connected with the radial air passage.
[0010] It is desirable for the outer air passage and the radial
air passage to be configured so that a velocity of airflow increases
in a direction of flow from the outer air passage to the radial
air passage.
[0011] It is desirable for the outer-air-passage forming surface
and the radial-air-passage forming surface to be connected to each
other via a curved surface.
[0012] It is desirable for the at least one suction port to be
formed in the radial-air-passage forming surface at a position away
from a center of the radial-air-passage forming surface.
[0013] It is desirable for the cleaning attachment to include a
connecting body which is detachably attached to the mount portion
of the camera body and supports the facing member.
[0014] It is desirable for the cleaning attachment to include a
support frame immovable relative to the connecting body, wherein
the facing member is supported by the support frame to be movable
relative to the support frame in a direction to move toward and
away from the front surface of the image pickup device. The facing
member is biased in a direction away from a limit of movement thereof
closest to the front surface of the image pickup device. The cleaning
attachment further includes a stop mechanism for maintaining a gap
between the rear surface of the facing member and the front surface
of the image pickup device at a constant size when the facing member
is moved to the limit of movement of the facing member.
[0015] It is desirable for the connecting body to be in the shape
of a hood having an open end and a closed end at opposite ends thereof,
respectively, the open end of the hood being detachably attached
to the mount portion of the camera body.
[0016] It is desirable for the cleaning attachment to include at
least one spacer which projects from the radial-air-passage forming
surface, and comes in contact with a part of the front surface of
the image pickup device which faces the periphery of an effective
imaging area of the image pickup device to form the radial air passage
between the front surface of the image pickup device and the radial-air-passage
forming surface.
[0017] It is desirable for the image pickup device to include an
image pickup element, and an optical covering element positioned
immediately in front of the image pickup element.
[0018] It is desirable for the suction port to be formed at a center
of the radial-air-passage forming surface.
[0019] It is desirable for the circumferential frame to have a
rectangular shape in cross section taken along a plane orthogonal
to the optical axis direction.
[0020] It is desirable for the connection between the outer-air-passage
forming surface and the radial-air-passage forming surface to be
chamfered so as to form the curved surface.
[0021] It is desirable for the at least one suction port to include
two suction ports made in the radial-air-passage forming surface
on opposite sides of the center thereof, respectively.
[0022] It is desirable for the digital camera to include a single-lens-reflex
camera.
[0023] In an embodiment, a cleaning attachment is provided, for
removing dust stuck to a front surface of an image pickup device
provided in a camera body of a digital camera using an interchangeable
lens capable of being detachably attached to a mount portion of
the camera body, the cleaning attachment including a mount portion
which is detachably attached to the mount portion of the camera
body; a facing member which faces the front surface of the image
pickup device; a circumferential frame provided around the facing
member to form a first outer air passage and a second outer air
passage between the circumferential frame and the facing member
on opposite sides of the facing member, respectively; a radial-air-passage
forming surface, formed on a rear surface of the facing member to
extend parallel to the front surface of the image pickup device,
for forming a radial air passage between the radial-air-passage
forming surface and the front surface of the image pickup device,
the radial air passage extending orthogonally to the optical axis
and communicatively connected with each of the first outer air passage
and the second outer air passage; and a suction device, communicatively
connected with the second outer air passage, for producing a flow
of air in a direction of flow from the first outer air passage to
the second outer air passage through the radial air passage. The
first outer air passage is configured so that the velocity of airflow
increases in a direction of flow from the first outer air passage
to the radial air passage.
[0024] It is desirable for the cleaning attachment to include a
connecting body which is detachably attached to the mount portion
of the camera body and supports the facing member.
[0025] It is desirable for the cleaning attachment to include a
support frame immovable relative to the connecting body, wherein
the facing member is supported by the support frame to be movable
relative to the support frame in a direction to move toward and
away from the front surface of the image pickup device. The facing
member is biased in a direction to approach the front surface of
the image pickup device. The cleaning attachment further includes
a stop device which moves with the facing member and separates the
radial-air-passage forming surface from the front surface of the
image pickup device by being brought into contact with the front
surface of the image pickup device to form the radial air passage
between the radial-air-passage forming surface and the front surface
of the image pickup device.
[0026] It is desirable for the connecting body to be in the shape
of a hood having an open end and a closed end at opposite ends thereof,
respectively, the open end of the hood being detachably attached
to the mount portion of the camera body.
[0027] It is desirable for a connection between the first outer
air passage and the radial air passage to have a curved surface,
and for a connection between the second outer air passage and the
radial air passage includes a curved surface.
[0028] It is desirable for the image pickup device to include an
image pickup element, and an optical covering element positioned
immediately in front of the image pickup element.
[0029] It is desirable for the digital camera to be a single-lens-reflex
camera.
[0030] According to an aspect of the present invention, the radial
air passage that extends orthogonal to an optical axis of the digital
camera according to the present invention gradually decreases in
the direction toward the suction port from the outer edge of the
radial air passage. Therefore, the velocity of the air flow in the
radial air passage gradually increases in the direction toward the
suction port according to the Bernoulli effect. Since the Bernoulli
effect can be expressed by the following expression: Q (quantity
of flow)=A (cross-sectional area).times.V (velocity of flow), the
velocity of flow V increases as the cross-sectional area A reduces
if the quantity of flow Q is constant. Dust stuck to the front surface
of the image pickup device is removed by this accelerated airflow,
and accordingly, such dust can be removed in an efficient manner
with no need to increase the size of the suction device.
[0031] If the velocity of the flow of air into the radial air passage
from the outer air passage is increased, the effect of removing
dust stuck to the front surface of the image pickup device is enhanced.
[0032] In the case where the facing member is movable in a direction
toward and away from the image pickup device, the facing member
is subjected to a force biasing the facing member close to the front
surface of the image pickup device because the air pressure in the
radial air passage drops when air flows at a high velocity in the
radial air passage. However, if the cleaning attachment is provided
with the stopper mechanism or the spacer, the gap between the radial-air-passage
forming surface (rear surface of the facing member) and the front
surface of the image pickup device can be maintained at a constant
size while the radial-air-passage forming surface and the front
surface of the image pickup device can be prevented from interfering
with each other.
[0033] The present disclosure relates to subject matter contained
in Japanese Patent Application No. 2005-358995 (filed on Dec. 13,
2005), which is expressly incorporated herein in its entirety.
BRIEF DESCRIPTION OF THE DRAWINGS
[0034] The present invention will be discussed below in detail
with reference to the accompanying drawings, in which:
[0035] FIG. 1 is a longitudinal cross sectional view of an SLR
digital camera to which a first embodiment of a cleaning attachment
according to the present invention is mounted;
[0036] FIG. 2 is an enlarged longitudinal cross sectional view
of a cleaner portion of the cleaning attachment, an optical covering
element and a portion around the perimeter of the optical covering
element;
[0037] FIG. 3 is a view similar to that of FIG. 2 in a state where
a suction device is in operation;
[0038] FIG. 4 is a cross sectional view taken along IV-IV line
shown in FIG. 2, viewed in the direction of the appended arrows,
in a state where an inner frame of the cleaning attachment is removed;
[0039] FIG. 5 is a rear elevational view of a circumferential frame
and the inner frame of the cleaning attachment, viewed from the
image pickup device side;
[0040] FIG. 6 is a rear elevational view of the inner frame, illustrating
the areas of cross sections of radial air passages at the respective
positions thereof, taken along a plane orthogonal to an airflow
direction;
[0041] FIG. 7 is a rear elevational view of a second embodiment
of the cleaning attachment according to the present invention;
[0042] FIG. 8 is a cross sectional view taken along VIII-VIII line
shown in FIG. 7, viewed in the direction of the appended arrows;
[0043] FIG. 9 is a view similar to that of FIG. 2, showing a state
where the second embodiment of the cleaning attachment is attached
to the camera body;
[0044] FIG. 10 is a cross sectional view taken along X-X line shown
in FIG. 9, viewed in the direction of the appended arrows;
[0045] FIG. 11 is a cross sectional view taken along XI-XI line
shown in FIG. 9, viewed in the direction of the appended arrows;
[0046] FIG. 12 is a view similar to that of FIG. 5, showing the
circumferential frame and the inner frame of another embodiment
of the cleaning attachment;
[0047] FIG. 13 is a view similar to that of FIG. 5, showing the
circumferential frame and the inner frame of another embodiment
of the cleaning attachment; and
[0048] FIG. 14 is an enlarged longitudinal sectional view of portions
of the inner frame and the optical covering element that are shown
in FIG. 13.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0049] A first embodiment of a cleaning attachment 30 which is
mounted to an SLR digital camera 10 when in use will be hereinafter
discussed with reference to the attached drawings. In the following
description, the object side and the image-forming surface side
are referred to as front side and rear side, respectively.
[0050] Firstly, the structure of a camera body 10 of the SLR digital
camera to which the cleaning attachment 30 is mounted will be hereinafter
discussed.
[0051] The camera body 10 is provided on a front surface of the
camera body 10 with a circular opening 11, and is further provided
around the circular opening 11 with a mount portion 12 in the shape
of a ring as viewed from the front of the camera body 10. Ann interchangeable
lens (not shown) or the cleaning attachment 30 can be freely detachably
attached to the mount portion 12. The letter "O" shown
in FIG. 1 designates the location of an optical axis of a photographing
optical system (lens groups) provided in an interchangeable lens
(not shown) when attached to the mount portion 12. The camera body
10 is provided therein with a holder 13 which is fixed to a front
surface (inner surface) of a rear wall of the camera body 10. The
camera body 10 is further provided therein with an image pickup
element 14, and an optical covering element 16 which is positioned
immediately in front of the image pickup element 14 to cover the
front surface of the image pickup element 14. The image pickup element
14 and the optical covering element 16 are immovably supported by
the holder 13. The optical covering element 16 can be an optical
low-pass filter, an infrared cutoff filter, a cover glass, or the
like. Note that the image pickup element 14 and the optical covering
element 16 are elements of a solid-state image pickup device (imaging
device) in this particular embodiment. Each of an imaging surface
(light-receptive surface) 15 of the image pickup element 14 and
the front surface of the optical covering element 16 is a flat surface
orthogonal to the optical axis 0 shown in FIG. 1.
[0052] The camera body 10 is provided therein at the top of the
internal space with a pentagonal prism 17, an eyepiece 18 and a
viewfinder window 19, which constitute a viewfinder optical system.
The camera body 10 is provided therein below the pentagonal prism
17 with a pivot (horizontal pivot shaft) 20, the opposite ends of
which are rotatably supported by right and left internal walls of
the camera body 10, respectively, and is further provided in the
camera body 10 with a quick-return mirror 21, the rear edge of which
is pivoted to the pivot 20. As known in the art,before a shutter
release button (not shown) of the camera body 10 is depressed, the
quick-return mirror 21 is positioned in the viewing position (down
position) thereof (not shown), in which the quick-return mirror
21 is positioned at approximately 45 degrees to interfere with the
optical axis 0 so as to reflect the incident light that is passed
through the lens groups of the attached interchangeable lens to
be incident on the quick-return mirror 21, toward the pentagonal
prism 17, to allow the photographer to view an object image through
the viewfinder window 19 via the eyepiece 18. On the other hand,
upon the shutter release button being depressed, the mirror 21 rises
to the retracted position shown in FIG. 1 to allow the image pickup
element 14 to capture an image passed through the lens groups of
the attached interchangeable lens. The camera body 10 is provided
therein in front of the holder 13 with a focal plane shutter having
of a plurality of shutter blades SH (which is in the fully opened
state thereof in FIG. 1).
[0053] The structure of the cleaning attachment 30 will be discussed
hereinafter.
[0054] The cleaning attachment 30 is provided with a hood portion
(connecting body) 31 having a cylindrical shape, the front end (left
end as viewed in FIG. 1) of which is closed. The rear end of the
hood portion 31 is formed as an open end, and the hood portion 31
is provided at the rear end thereof with a mount portion 32 which
can be freely detachably attached to the mount portion 12 of the
camera body 10. The hood portion 31 is provided therein with an
internal plate 33 which is fixed to an inner peripheral surface
of the hood portion 31 and which lies in a plane orthogonal to the
optical axis 0 when the hood portion 31 is attached to the mount
portion 12 of the camera body 10. The cleaning attachment 30 is
provided with a suction device 35 which is fixed to a rear surface
of the internal plate 33 substantially at a central portion thereof.
The cleaning attachment 30 is provided on the rear surface of the
internal plate 33 with a rectangular hollow member 36, both the
front and rear ends of which are formed as open ends. The rectangular
hollow member 36 is fixed at the front end thereof to the rear surface
of the internal plate 33. A connecting hole (radial through hole)
36a (see FIG. 1), through which the radially outside and the radially
inside of the rectangular hollow member 36 are communicatively connected
to each other, is bored through the rectangular hollow member 36.
[0055] As shown in FIG. 2 in detail, the cleaning attachment 30
is provided with a circumferential frame 37 having a rectangular
shape as viewed from the front thereof. A front surface of the circumferential
frame 37 is fixed to a rear end surface of the rectangular hollow
member 36. The circumferential frame 37 is provided, on top and
bottom walls thereof in the vicinity of the rear end of the circumferential
frame 37, with a pair of stop holes (elements of a stop mechanism/upper
and lower stop holes) 38, respectively.
[0056] The cleaning attachment 30 is provided inside the rectangular
hollow member 36 with a support cylinder 40, the front end of which
extends rearward to be joined to the suction device 35. The cleaning
attachment 30 is provided inside the circumferential frame 37 with
a bottomed support frame 41 which is formed integral with an outer
peripheral surface of the support cylinder 40. The support frame
41 and the circumferential frame 37 are coupled to each other by
eight coupling pieces 39 (see FIGS. 4 and 5). The radially outer
end of each coupling piece 39 is fixed to the inner peripheral surface
of the circumferential frame 37 at the front end thereof, while
the radially inner end of each coupling piece 39 is fixed to the
outer peripheral surface of the support frame 41 at the front end
thereof. Accordingly, the circumferential frame 37, the eight coupling
pieces 39, the support cylinder 40 and the support frame 41 are
formed as a single member by integral molding. Eight spaces (holes)
are formed between the circumferential frame 37 and the support
frame 41 at the front ends thereof, wherein the eight spaces are
partitioned by the eight coupling pieces 39 for the separate accommodation
of eight filters F that catch minute dust. The eight filters F are
fixedly fitted in the aforementioned eight spaces (holes).
[0057] As shown in FIG. 4 a clearance having a rectangular shape
as viewed from the front thereof is formed between the outer peripheral
surface of the support frame 41 and the inner peripheral surface
of the circumferential frame 37. The cleaning attachment 30 is provided
inside the circumferential frame 37 with an inner frame (facing
member) 43 which is fitted on the outer peripheral surface of the
support frame 41 to be freely slidable thereon. The outer peripheral
surface of the inner frame 43 serves as an outer-air-passage forming
surface 44 for forming an outer air passage L1 between the outer-air-passage
forming surface 44 and the inner peripheral surface of the circumferential
frame 37. The inner frame 43 is provided at a center thereof with
an integrated central cylindrical portion 45 which extends forward
from the rear end of the inner frame 43. The front end of the central
cylindrical portion 45 is fitted into the support cylinder 40 to
be slidable on the inner peripheral surface thereof. The internal
spaces of the central cylindrical portion 45 and the support cylinder
40 cooperatively form a central air passage.
[0058] The rear end surface of the inner frame 43 is formed as
a flat surface parallel to the optical covering element 16 and serves
as a radial-air-passage forming surface 46 in a state where the
cleaning attachment 30 is mounted to the camera body 10. The rear
end surface of the inner frame 43 lies in a plane substantially
orthogonal to the outer-air-passage forming surface 44. A radial
air passage L2 is formed between the radial-air-passage forming
surface 46 and the front surface of the optical covering element
16 to extend in radial directions orthogonal to the optical axis
0 in a state where the cleaning attachment 30 is mounted to the
camera body 10. The rear end opening of the central cylindrical
portion 45 is open at the center of the radial-air-passage forming
surface 46 to serve as a suction port 47. A rear circumferential
outer edge (connecting portion/joint) 48 of the inner frame 43 that
is positioned at the rear end thereof is chamfered and serves as
a part of the outer-air-passage forming surface 44.
[0059] The inner frame 43 is provided, on a top surface portion
and a bottom surface portion of the outer peripheral surface of
the outer-air-passage forming surface 44, with an upper partition
plate 49 and a lower partition plate 49 which extend in the forward/rearward
direction (the direction of the optical axis 0) and which project
upward and downward from the top surface and the bottom surface
of the outer-air-passage forming surface 44, respectively. The top
surface and the bottom surface of the outer-air-passage forming
surface 44 face the pair of stop holes (upper and lower stop holes)
38, respectively. The upper partition plate 49 and the lower partition
plate 49 are provided at the rear ends thereof with an upper stop
projection (an element of the stop mechanism) 50 and a lower stop
projection (an element of the stop mechanism) 50 which extend radially
outwards and are engaged in the upper and lower stop holes 38 to
be slidingly movable therein in the optical axis direction (horizontal
direction as viewed in FIGS. 1 through 3), respectively. Namely,
the inner frame 43 is slidingly movable in the forward/rearward
direction relative to the circumferential frame 37 and the support
frame 41 between the front moving limit (the position shown in FIG.
2) defined by the engagement of each stop projection 50 with the
front end of the associated stop hole 38 and the rear moving limit
(the position shown in FIG. 3) defined by the engagement of each
stop projection 50 with the rear end of the associated stop hole
38. Additionally, the cleaning attachment 30 is provided with extension
springs (biasing device) S1 which are extended and installed between
the base (rearward-facing surface) of the support frame 41 and the
rear end wall of the inner frame 43. Specifically, the front ends
and the rear ends of the extension springs S1 are fixed to the base
of the support frame 41 and the rear end wall of the inner frame
43, respectively, so that the inner frame 43 is continuously biased
forward, away from the front surface of the optical covering element
16, by the pulling spring force of the extension springs S1.
[0060] The procedure for cleaning the front surface of the optical
covering element 16 with the cleaning attachment 30 having the above
described structure will be discussed hereinafter.
[0061] First of all, by an operation of a specific switching mechanism
(for example, by pushing a cleaning switch button provided on the
camera body (not shown)), the shutter blades SH of the focal plane
shutter are fully opened and the mirror 21 moves to the retracted
position. Subsequently, the cleaning attachment 30 is mounted to
the camera body 10 by coupling the mount portion 32 of the cleaning
attachment 30 to the mount portion 12 of the camera body 10 from
which an interchangeable lens is detached. In a state where the
cleaning attachment 30 is mounted to the camera body 10, dust is
prevented from entering the inside of the camera body 10 through
the circular opening 11 by the hood portion 31. Thereupon, as shown
in FIGS. 2 and 3, the rear end of the circumferential frame 37 passes
through the fully-opened aperture of the focal plane shutter (having
the shutter blades SH) and approaches the optical covering element
16.
[0062] Subsequently, upon the cleaning attachment 30 being mounted
to the camera body 10, the radial-air-passage forming surface 46
is positioned closely to the front surface of the optical covering
element 16 to be parallel thereto as shown in FIG. 2 to form the
radial air passage L2 between the radial-air-passage forming surface
46 and the front surface of the optical covering element 16. Note
that the clearance created between the rear end surface of the circumferential
frame 37 and the front surface of the optical covering element 16
is minimal as shown in FIGS. 2 and 3. In addition, the outer air
passage L1 is already formed between the inner frame 43 (the outer-air-passage
forming surface 44 and the rear circumferential outer edge 48) and
the circumferential frame 37 before the cleaning attachment 30 is
mounted to the camera body 10.
[0063] Upon the suction device 35 being actuated in the state shown
in FIG. 2, the negative pressure produced by the suction device
35 causes the air outside the rectangular hollow member 36 to firstly
enter inside the rectangular hollow member 36 through the connecting
hole 36a and subsequently flow in the directions shown by the arrows
shown in FIG. 3. Namely, the air flowing into the rectangular hollow
member 36 flows into the radial air passage L2 through the outer
air passage L1, subsequently flows into the central air passage,
which is formed by the central cylindrical portion 45 and the support
cylinder 40, via the suction port 47, and is ultimately sucked by
the suction device 35. At this time, this air flows from the outer
air passage L1 into the radial air passage L2 along the curved surface
(chamfered corner) of the rear circumferential outer edge 48 of
the inner frame 43 with a Coanda effect (boundary layer attachment),
and therefore flows from the outer air passage L1 into the radial
air passage L2 efficiently.
[0064] The dimensions of the outer air passage L1 and the radial
air passage L2 are determined so that the area of a cross section
of the radial air passage L2 taken along a plane orthogonal to the
direction of the airflow in the radial air passage L2 becomes smaller
than the area of a cross section of the outer air passage L1 taken
along a plane orthogonal to the direction of the airflow in the
outer air passage L1. More specifically, the following expression
is satisfied: CA1>CA2
[0065] wherein CA1 represents the area of a cross section of the
outer air passage L1 taken along a plane orthogonal to the direction
of the airflow in the outer air passage L1, and CA2 represents the
area of a cross section of the radial air passage L2 taken along
a plane orthogonal to the direction of the airflow in the radial
air passage L2.
[0066] Therefore, when air flows into the outer edge of the radial
air passage L2 from the outer air passage L1, the velocity of this
airflow increases by a decrease in cross-sectional area of the air
passage (Bernoulli effect). Namely, the following expression is
satisfied: V2>V1
[0067] wherein V1 represents the velocity of the airflow in the
outer air passage L1, and
[0068] V2 represents the velocity of the airflow in the radial
air passage L2.
[0069] As shown in FIG. 6, the area of a cross section of the radial
air passage L2 taken along a plane orthogonal to the direction of
the airflow in the radial air passage L2 gradually decreases in
the direction toward the suction port 47 (the central air passage)
from the outer edge of the radial air passage L2. FIG. 6 shows ring-shaped
sections P1, P2 and P3 which are concentrically arranged about the
suction port 47. The following expression is satisfied: CA1>CA2>CA3>CA4>CA5
[0070] wherein CA3, CA4 and CA5 represent the area of a cross section
of the ring-shaped section P1 taken along a plane orthogonal to
the direction of the airflow in the ring-shaped section P1, the
area of a cross section of the ring-shaped section P2 taken along
a plane orthogonal to the direction of the airflow in the ring-shaped
section P2, and the area of a cross section of the ring-shaped section
P3 taken along a plane orthogonal to the direction of the airflow
in the ring-shaped section P3, respectively.
[0071] Therefore, the following expression is satisfied: V5>V4>V3>V2>V1
[0072] wherein V3 represents the velocity of the airflow in the
ring-shaped section P1,
[0073] V4 represents the velocity of the airflow in the ring-shaped
section P2, and
[0074] V5 represents the velocity of the airflow in the ring-shaped
section P3.
[0075] The airflow accelerated in this manner from the airflow
velocity V1 to the air velocity V5 removes dust stuck to the front
surface of the optical covering element 16, and accordingly, such
dust on the front surface of the optical covering element 16 can
be reliably removed with no need to increase the size of the suction
device 35 in order to produce a greater suction power.
[0076] The passage of air through the radial air passage L2 at
the airflow velocities V2, V3, V4 and V5 in this order causes the
air pressure in the radial air passage L2 to become lower than that
before the actuation of the suction device 35. This reduction of
the air pressure in the radial air passage L2 causes the inner frame
43 to move rearward to the aforementioned rear moving limit thereof
against the pulling spring force of the extension springs S1 i.e.,
to the position shown in FIG. 3. If the width of the radial air
passage L2 in the optical axis direction further narrows in this
manner, the velocity of the air passing through the radial air passage
L2 becomes higher than that before the inner frame 43 moves rearward,
which makes it possible to remove dust stuck to the front surface
of the optical covering element 16 in a more efficient manner.
[0077] A second embodiment of a cleaning attachment 60 according
to the present invention will be hereinafter discussed with reference
to FIGS. 7 through 11. Elements of the second embodiment of the
cleaning attachment 60 which are similar to those of the first embodiment
of the cleaning attachment 30 are designated by the same reference
numerals, and a detailed description of such elements are omitted
from the following description.
[0078] The second embodiment of the cleaning attachment 60 is provided
with a support frame 61 which is fixed to a rear end surface of
the rectangular hollow member 36.
[0079] The support frame 61 is provided with a fixing portion 62
in the shape of a flat plate which is fixed to the rear end surface
of the rectangular hollow member 36, and is provided with an outer
rectangular hollow portion 63 which is integral with the fixing
portion 62 and projects from the rear end surface of the rectangular
hollow member 36. The support frame 61 is further provided on a
rear surface of the fixing portion 62 with a pair of air-passage
forming wall portions 64 and an end wall portion 65 which are integral
with the fixing portion 62. The pair of air-passage forming wall
portions 64 extend rearward so as to be parallel to each other,
and the end wall portion 65 also extends rearward to close one of
the two gaps (specifically, the bottom gap as viewed in FIGS. 8
and 9) respectively made at the opposite ends (the top and bottom
ends as viewed in FIGS. 8 and 9) of the pair of air-passage forming
wall portions 64. The support frame 61 is further provided immediately
behind the pair of air-passage forming wall portions 64 and the
end wall portion 65 with a support portion 66 in the shape of a
flat plate which is integrally fixed to rear end surfaces of the
pair of air-passage forming wall portions 64 and the end wall portion
65. The support frame 61 is further provided immediately behind
the support portion 66 with an inner rectangular hollow portion
(support frame) 67 which is integral with the support portion 66
and projects rearward from the outer edge of the rear end surface
of the support portion 66.
[0080] The fixing portion 62 is provided between the front ends
of the pair of the air-passage forming wall portions 64 with a through
hole 68 in which a filter F2 is fixedly fitted. The fixing portion
62 is further provided with a through hole 69 (see FIG. 8 and 9)
in which a filter F3 is fixedly fitted. The cleaning attachment
60 is provided, in an air passage formed among the pair of air-passage
forming wall portions 64, the end wall portion 65 and the support
portion 66, with a fan 70 serving as a suction device. The outer
rectangular hollow portion 63 is provided with twelve guide support
holes 71 which are elongated in the forward/rearward direction and
arranged circumferentially at predetermined intervals.
[0081] As shown in FIG. 7, the cleaning attachment 60 is provided
between the outer rectangular hollow portion 63 and the inner rectangular
hollow portion 67 of the support frame 61 with a clearance (receptive
space) having a rectangular shape as viewed from the front thereof,
and is provided in this clearance with an outer frame (circumferential
frame/stop device) 72 and an inner frame (facing member) 73 which
are integrally formed with each other (see FIG. 8). The outer frame
72 is slidably fitted in the outer rectangular hollow portion 63
to be slidingly movable in the forward/rearward direction relative
to the outer rectangular hollow portion 63, and the inner frame
73 is slidably fitted on the inner rectangular hollow portion 67
to be slidingly movable in the forward/rearward direction relative
to the inner rectangular hollow portion 67.
[0082] The outer frame 72, the outer peripheral surface of which
is in contact with the inner peripheral surface of the outer rectangular
hollow portion 63 to be slidable thereon, is provided at twelve
positions on the outer peripheral surface thereof, which respectively
correspond the positions of the twelve guide support holes 71, with
twelve guide projections 74 which are engaged in the twelve guide
support holes 71 to be slidingly movable in the forward/rearward
direction relative to the twelve guide support holes 71, respectively.
[0083] As shown in FIG. 7, right and left outer side surfaces of
the inner frame 73 are firmly fitted to right and left inner side
surfaces of the outer frame 72 to be fixed thereto with no gap therebetween,
respectively. The bottom surface of the inner frame 73 serves as
a first outer-air-passage forming surface 76, and a first outer
air passage L3 is formed between the first outer-air-passage forming
surface 76 and the bottom wall 5 portion of the outer frame 72.
The top surface of the inner frame 73 serves as a second outer-air-passage
forming surface 77, and a second outer air passage L4 is formed
between the second outer-air-passage forming surface 77 and the
top wall portion of the outer frame 72. The rear end surface of
the inner frame 73 serves as a radial-air-passage forming surface
78 which is formed as a flat surface parallel to the optical covering
element 16. The outer frame also separates the radial-air-passage
forming surface 78 from the optical covering element 16, as shown
in FIGS. 9 through 11.
[0084] Similar to the rear circumferential outer edge 48 of the
inner frame 43 in the first embodiment of the cleaning attachment
30, a rear circumferential outer edge 79 of the inner frame 73 that
is positioned at the rear end thereof is chamfered and serves as
a part of the first outer-air-passage forming surface 76 and apart
of the second outer-air-passage forming surface 77. The rear circumferential
outer edge 79 of the inner frame 73 also serves as a connecting
portion by which the radial-air-passage forming surface 78 and the
first outer-air-passage forming surface 76 are connected, and also
serves as a connecting portion by which the radial-air-passage forming
surface 78 and the second outer-air-passage forming surface 77 are
connected. As shown in the drawings, the cleaning attachment 60
is provided with compression springs (biasing device) S2 which are
compressed so as to be installed between the a rear surface of the
support portion 66 and a front surface of the rear end wall of the
inner frame 73. Therefore, the outer frame 72 and the inner frame
73 are continuously biased rearward by the compression springs S2
to bring the twelve guide projections 74 to be biased against the
rear ends of the twelve guide support holes 71, respectively, as
shown in FIG. 8.
[0085] The procedure for cleaning the front surface of the optical
covering element 16 with the cleaning attachment 60 that has the
above described structure will be discussed hereinafter.
[0086] First of all, likewise with the first embodiment, in the
state where the quick-return mirror 21 is retracted to the position
shown in FIG. 1 and the focal plane shutter SH being fully opened,
the cleaning attachment 60 is mounted to the camera body 10 by coupling
the mount portion 32 of the cleaning attachment 60 to the mount
portion 12 of the camera body 10 from which an interchangeable lens
is detached. At this time, the rear end of the outer frame 72 passes
through the fully-opened aperture of the focal plane shutter (consisting
of the shutter blades SH) and comes into contact with the front
surface of the optical covering element 16 as shown in FIGS. 9 through
11. Thereupon, as shown in FIGS. 9 through 11, the outer frame 72
and the inner frame 73 move forward relative to the outer rectangular
hollow portion 63 against the biasing force of the compression springs
S2, while the radial-air-passage forming surface 78 of the inner
frame 73 which approaches the front surface of the optical covering
element 16 parallel to the radial-air-passage forming surface 78
forms a radial air passage L5 between the radial-air-passage forming
surface 78 and the front surface of the optical covering element
16.
[0087] Upon the fan 70 being actuated in the state shown in FIG.
9, the negative pressure produced by the fan 70 causes the air which
exists outside the rectangular hollow member 36 to firstly enter
inside the rectangular hollow member 36 through the connecting hole
36a, and subsequently flow in the directions shown by the arrows
shown in FIG. 9. Namely, the air flowing into the rectangular hollow
member 36 firstly flows into the first outer air passage L3, subsequently
flows from the first outer air passage L3, the radial air passage
L5 to the second outer air passage L4 in that order (see the arrows
shown in FIGS. 9 through 11), subsequently passes through the fan
70 and flows back into the rectangular hollow member 36 through
the filter F2. At this time, this air flows from the first outer
air passage L3 to the radial air passage L5 along the curved surface
(chamfered corner) of the rear circumferential outer edge 79 of
the inner frame 73 with a Coanda effect (boundary layer attachment),
and subsequently flows from the radial air passage L5 to the second
outer air passage L4 along the curved surface (chamfered corner)
of the rear circumferential outer edge 79 of the inner frame 73
with a Coanda effect (boundary layer attachment), and accordingly
flows from the first outer air passage L3 to the second outer air
passage L4 efficiently.
[0088] Similar to the outer air passage L1 and the radial air passage
L2 in the first embodiment of the cleaning attachment 30, the dimensions
of the first outer air passage L3, the second outer air passage
L4 and the radial air passage L5 are determined so that the area
of a cross section of the radial air passage LS taken along a plane
orthogonal to the direction of the airflow in the radial air passage
L5 becomes smaller than each of the area of a cross section of the
first outer air passage L3 taken along a plane orthogonal to the
direction of the airflow in the first outer air passage L3 (which
includes the area of a cross section of a portion of the first outer
air passage L3 which is formed between the rear circumferential
outer edge 79 and the outer frame 72) and the area of a cross section
of second outer air passage L4 taken along a plane orthogonal to
the direction of the airflow in second outer air passage L4 (which
includes the area of a cross section of a portion of the second
outer air passage L4 which is formed between the rear circumferential
outer edge 79 and the outer frame 72) Therefore, when air flows
into the outer edge of the radial air passage L5 from the first
outer air passage L3, the velocity of this airflow increases by
a decrease in cross-sectional area of the air passage. Namely, the
following expression is satisfied: V2>V1
[0089] wherein V1 represents the velocity of the airflow in the
outer air passage L3, and
[0090] V2 represents the velocity of the airflow in the radial
air passage L5.
[0091] The airflow accelerated in this manner from the airflow
velocity VI to the air velocity V2 removes dust stuck to the front
surface of the optical covering element 16, and accordingly, such
dust on the front surface of the optical covering element 16 can
be reliably removed, and similar to the first embodiment of the
cleaning attachment 30, there is no need to increase the size of
the suction device 35 in order to produce a greater suction power.
[0092] Although the present invention has been discussed with reference
to the specific embodiments described above, the present invention
is not limited solely thereto; various changes can be made in these
specific embodiments without departing from the scope of the invention
claimed.
[0093] For instance, it is possible that the cleaning attachment
be provided, on the radial-air-passage forming surface 46 at two
positions thereon laterally away from the center of the radial-air-passage
forming surface 46, with two suction ports 51 (each of which corresponds
to the suction port 47 shown in FIG. 5) as shown in FIG. 12 in the
first embodiment of the cleaning attachment (the two suction ports
51 are communicatively connected to the suction device 35 although
the structure thereof is not shown in the drawings). The two portions
of the radial-air-passage forming surface 46 in which the two suction
ports 51 are made are portions of the radial-air-passage forming
surface 46 where there is a possibility of the airflow stagnating
in the case where no suction ports are made. Therefore, if the airflow
stagnates at the two portions of the radial-air-passage forming
surface 46, dust will remain on two portions (portions having a
harmful effect on image quality if having dust thereon) of the front
surface of the optical covering element 16 which face the two portions
of the radial-air-passage forming surface 46, respectively. However,
providing the two suction ports 51 in this manner makes it possible
to effectively prevent such dust stuck to such two portion of the
front surface of the optical covering element 16 from remaining.
[0094] Additionally, in the embodiment shown in FIGS. 13 and 14,
it is possible for four spacers (spacers for formation of an air
passage) 53, which come in contact with the front surface of the
optical covering element 16 when the inner frame 43 is drawn toward
the optical covering element 16 upon the air pressure in the outer
air passage L1 falling, be installed at four portions of the radial-air-passage
forming surface 46 in the vicinity of the four corners thereof,
respectively, which face the periphery of the effective imaging
area of the imaging surface 15. By providing the spaces 53 in such
a manner, the length (thickness) of the outer air passage L1 in
the forward/rearward direction, which is formed between the radial-air-passage
forming surface 46 and the optical covering element 16, can be freely
set by freely determining the thickness of the spacers 53 in the
forward/rearward direction, and accordingly, the effect of removing
dust stuck to the optical covering element 16 can be adjusted by
freely determining the thickness of the spacers 53 in the forward/rearward
direction.
[0095] If the camera body 10 is not provided with the optical covering
element 16, the imaging surface 15 of the image pickup element 14
can be cleaned by airflow from the cleaning attachment (30 or 60).
[0096] It is possible that the support cylinder 40 be replaced
by a connecting tube made of rubber.
[0097] Obvious changes may be made in the specific embodiments
of the present invention described herein, such modifications being
within the spirit and scope of the invention claimed. It is indicated
that all matter contained herein is illustrative and does not limit
the scope of the present invention. |