JP2003143448A - Image pickup device and mechanism for holding low-pass filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To hold a low-pass filter in a small space (thinning). SOLUTION: An LPF cover plate 7 constituted of a thin metal plate is integrated with an LPF frame 6 made of a resin on which an LPF 5 is fitted, thereby constituting an LPF holder (LPF unit 11). This LPF unit 11 is integrated with a CCD unit 10 through an LPF spacer 4 by LPF pressing springs 8a, 8b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup apparatus such as a digital camera, and more particularly to a technique for holding a low pass filter.

[0002]

2. Description of the Related Art A holding mechanism for a low-pass filter (hereinafter abbreviated as LPF) used in a conventional digital camera or the like is disclosed in JP-A-2000-333050 and JP-A-20-32050.
No. 01-085655. In these, the LPF is bonded and fixed to the LPF holder, and the image pickup device is fixed by sandwiching an elastic member between the package of the image pickup device and the LPF.

Here, the elastic member serves to form a closed space between the LPF and the image pickup device, whereby foreign matter such as dust or dirt enters the vicinity of the image pickup device and a shadow of the foreign matter is reflected. It prevents it from getting lost.

Further, since the LPF holder must withstand the force of crushing the elastic member, it is necessary to have a strength capable of sufficiently withstanding this force. Further, since the processing accuracy of the image pickup device package is not so good, it is necessary to take a large amount of crushing of the elastic member in order to ensure a sealed space between the image pickup device package and the LPF. There is a need to.

[0005]

By the way, in a digital single-lens reflex camera with a small image-taking screen, the main mirror can be made small, and the shutter can be moved to the mount side by the size of the main mirror. Therefore, conventionally, in a camera having a small screen size, the position of the LPF holding mechanism is secured by changing the positions of the shutter and the main mirror.

However, in recent digital single-lens reflex cameras, the size of the main mirror cannot be reduced as the size of the image pickup device increases. For this reason, in a digital camera with a large photographic screen, the shutter cannot be moved to the mount side, making it difficult to increase the distance between the shutter and the image sensor.
It is becoming difficult to secure a space for arranging the PF holder and the elastic member having a large thickness.

The present invention has been made in view of the above problems of the prior art, and an object thereof is to be able to hold a low-pass filter in a small space (thinness).

[0008]

In order to solve the above-mentioned problems, the present invention provides an image pickup apparatus in which a lowpass filter is arranged in the vicinity of an image pickup element, and an image of a holding member holding the lowpass filter is picked up via a sheet-like spacer. The cover glass of the element package is held by being biased by a spring.

Further, according to the present invention, in a holding mechanism for a low-pass filter arranged near an image pickup device, a holding member holding the low-pass filter is spring-loaded to a cover glass of the image pickup device package via a sheet-shaped spacer. It is configured to be held by being biased by.

[0010]

FIG. 1 is an exploded perspective view of a solid-state image pickup section of a digital camera to which the present invention is applied. The solid-state image pickup section is roughly divided into a CCD plate 1 for holding a CCD package 2 which is an image pickup element, a base plate 3 which is a main structural member of the solid-state image pickup section, an LPF spacer 4, a low-pass filter (LPF) 5, and an LPF frame. 6, LP
The F cover plate 7 and the LPF pressing springs 8a and 8b are used.

FIG. 2 is a perspective view showing a state in which the CCD package 2 is adhered to the CCD plate 1. Where CCD
The four arm portions 1a, 1b, 1c, 1d of the plate 1 are
This is for fixing the CCD package 2 to the base plate 3 with solder or an adhesive after the alignment. A cover glass 2a is attached to one side (light receiving portion) of the CCD package 2.

FIG. 3 shows a CCD for the base plate 3.
State after aligning the light receiving part of the package 2
That is, the CCD unit 10 is shown.

Here, a ceramic package is generally used as a package of an image pickup device such as a CCD, but in a package of a large image pickup device, a manufacturing error of the package becomes large. In addition, the error in the attachment position when attaching the image pickup device in the package becomes large. Therefore, the positioning accuracy required for the camera cannot be obtained by the positioning based on the outer shape of the CCD package 2.

Therefore, in this embodiment, CC is attached to the base plate 3 serving as a reference when it is attached to the camera body.
The position of the light receiving portion of the D package 2 is adjusted to a predetermined position, and after this adjustment is performed, the four arm portions 3a, 3b, 3c, 3d of the base plate 3 and the facing portion 4 of the CCD plate 1 Arms 1a, 1b, 1c, 13d at several places
The gap between the two is filled with solder or an adhesive, and is fixed by being hardened to fix the CCD unit 1.
0 is completed.

The two pins 3e and 3f provided on the base plate 3 are guide pins for positioning when the CCD unit 10 is attached to the camera body or the position adjusting device. For this reason, the component of the solid-state image pickup unit that is most accurately attached to the camera body is the base plate 3.

FIG. 4 is an exploded perspective view for explaining the structure of the LPF unit 11. Low-pass filter (LP
F) 5 has a function of preventing point moire in a captured image by performing point image separation by a plurality of birefringent plates, and an infrared light cut function for preventing infrared light from entering the image sensor. Have This infrared light cut function is realized by an infrared light absorbing glass or an infrared light reflecting film, and this absorption and reflection may be used in combination. Therefore, the same effect can be obtained even if the holding mechanism according to the present invention is used in an infrared light cut filter.

The LPF holder is constructed by integrating a metal LPF cover plate 7 and a resin LPF frame 6. The LPF cover plate 7 is integrally fixed by engaging the upper and lower four engaging holes 7a and 7b with the engaging claws 6a and 6b of the LPF frame 6.

The LPF 5 is an opening (window) 6 in the LPF frame 6.
It is positioned in the vertical and horizontal directions by being fitted into W, and is positioned in the optical axis direction by abutting against the LPF cover plate 7.

That is, the opening (window) 6W of the LPF frame 6
Is the size of the part excluding the left and right expansion parts 6i and 6j,
It has the same size as the LPF 5, and the LPF 5 is fitted into the opening (window) 6W of the LPF frame 6, and the expansions 6i, 6 are formed.
It is fixed by filling j with an adhesive. As described above, by fitting the LPF 5 into the opening (window) 6W of the LPF frame 6, the expensive LPF 5 can be made as small as possible and the cost can be reduced.

The window 7W of the LPF cover plate 7 is
The LPF frame 6 that is slightly smaller than F5 is abutted against the LPF cover plate 7 by fitting the LPF 5 into the LPF frame 6 so that the LPF 5 does not deviate from the LPF frame 6 and the photographing light flux enters the outer peripheral portion of the LPF 5. Are prevented.

Thus, the LPF in which the LPF 5 is fitted
With the frame 6 abutting against the LPF cover plate 7, the LPF 5
The LPF unit 11 is completed by adhesively fixing the LPF frame 6 and the LPF cover plate 7.

By configuring the LPF unit 11 as described above, the LPF 5 is held in order to hold it.
The outer side (shutter side) requires only the thickness of the LPF cover plate 7, which is a very small space as compared with the conventional method. In addition, LPF holder (LP
Since a large force does not act on the F unit 11),
Since it is not necessary to give the LPF unit 11 high strength, the LPF unit 11 can be made smaller and lighter, and the LPF frame 6 made of a thin resin and the LPF cover plate 7 of a thin metal plate accommodating the LPF frame 6 can be used. , LPF5 can be held.

Further, since the outer peripheral portion of the LPF 5 is covered by the LPF cover plate 7, the photographing light flux does not enter the outer peripheral portion of the LPF 5, and the ghost can be prevented even if the LPF 5 is downsized. . In addition, the projections 6c, 6d, 6e, 6 provided at six positions on the upper, lower, left and right of the LPF frame 6
f, 6g, and 6h are for positioning the LPF unit 11, and the details will be described later.

The LPF unit 11 is replaced by the CCD unit 10
As shown in Fig. 5, when installing on LPF5 and C
By sandwiching the LPF spacer 4 between the cover glass 2a of the CD package 2, it is possible to prevent the LPF 5 and the cover glass 2a from being in direct contact with each other and prevent interference fringes from being generated in the gap between the LPF 5 and the cover glass 2a. is there.

The LPF spacer 4 is composed of a thin sheet-like member, and has a window 4W smaller than the LPF 5, and when the LPF unit 11 is incorporated into the CCD unit 10 via the LPF spacer 4, a CC
A sealed space is formed between the cover glass 2a of the D package 2 and the LPF 5 to prevent dust and dirt from entering from the outside. The LPF 5 is smaller than the cover glass 2a of the CCD package 2.

As described above, since the LPF spacer 4 is much thinner than the conventional elastic member, the LPF spacer 4 is
The holding mechanism occupies a smaller space than the conventional holding mechanism, and is a very effective holding mechanism for a digital single-lens reflex camera equipped with a large image sensor.

FIG. 6 is a diagram for explaining a method of attaching the LPF unit 11 to the CCD unit 10. L
To attach the PF unit 11 to the CCD unit 10, the LPF pressing springs 8a and 8b are used.

The LPF pressing springs 8a and 8b are made of conductive leaf springs and are attached to the attaching portions 3g and 3h of the base plate 3 by attaching screws 9a and 9b. At this time, the LPF pressing springs 8a and 8b are
Claws 7c, 7 provided upright on the upper and lower four places of the F cover plate 7
By urging the LPF cover plate 7 toward the base plate 3 via d, 7e, and 7f, the LPF unit 11 holding the LPF 5 acts to urge the CCD unit 10, that is, the cover glass 2a. To do.

At this time, the metal LPF cover plate 7 is connected to the base plate 3 via the conductive LPF pressing springs 8a and 8b. For this reason, when the base plate 3 is grounded, the LPF cover plate 7 is also grounded, which functions to block electromagnetic noise from the CCD package 2 and to shield it.

7 to 9 show a solid state image pickup unit in a completed state in which the LPF unit 11 is attached to the CCD unit 10 by the LPF pressing springs 8a and 8b.

The LPF unit 11 is replaced with the CCD unit 10
The solid-state image pickup unit attached to the mounting screws 13a, 13b,
It is attached to the camera body by 13c.

As described above, the solid-state image pickup unit can be unitized with the LPF unit 11 attached to the CCD unit 10. Therefore, by assembling the solid-state image pickup unit in a clean room, dust and dust can be present between the LPF 5 and the CCD package 2. Can be controlled so that the camera does not enter, eliminating the need to perform the main assembly of the camera in the clean room.

FIG. 10 is a diagram for explaining a method of positioning the LPF 5 in the vertical and horizontal directions. LPF5 is LP
Protrusions 6c, 6d, 6e, 6 fitted in the window 6W inside the F frame 6 and provided at six positions on the upper, lower, left and right sides of the LPF frame 6.
The LPF 5 is positioned in the vertical and horizontal directions by fitting the LPF frame 6 into the base plate 3 while being guided by f, 6g, and 6h.

Here, the base plate 3 is a component which is most accurately positioned with respect to the camera body. In this way, the vertical and horizontal directions are not the CCD package 2,
By positioning with the base plate 3 attached to the camera body most accurately, the LPF 5 can also be positioned with high accuracy with respect to the effective light flux (optical axis) for photographing. As a result, the margin amount from the effective light flux to the outer peripheral portion of the LPF 5 can be reduced, and the LPF 5 can be downsized and the cost can be reduced.

FIG. 11 is a central sectional view of the solid-state image pickup section. The CCD package 2 is adhesively fixed to the CCD plate 1, and the LPF 5 is connected to the LPF spacer 4 via the LPF spacer 4.
The holding springs 8a and 8b urge the cover glass 2a of the CCD package 2 toward the cover glass 2a.

As described above, the gap between the cover glass 2a of the CCD package 2 and the LPF 5 is determined by the thickness of the LPF spacer 4, and the thickness of the LPF spacer 4 can be made significantly thinner than that of the conventional elastic member. The holding mechanism can be made thinner.

Further, the space outside the LPF 5 (shutter side) is limited to the space corresponding to the thickness of the LPF cover plate 7, and a large space unlike the conventional resin LPF holder is not required. In addition, the LPF holding mechanism can be made thinner.

As described above, in the LPF holding mechanism according to the present embodiment, the thickness of the member holding the LPF 5 in the optical axis direction can be greatly reduced, and the LPF holding in the digital single lens reflex camera using the large image pickup device can be performed. It is possible to solve the problem of insufficient space in the mechanism.

Further, the LPF 5 and the cover glass 2a of the CCD package 2 are made thin while the LPF holding mechanism is made thin.
Since the space between and is a space sealed by the LPF spacer 4, it becomes possible to prevent dust and dirt from entering from the outside.

Further, since the LPF cover plate 7 covers the outer peripheral portion of the LPF 5 so that the photographing light flux does not enter from the outer peripheral portion of the LPF 5, it is possible to prevent ghosts due to reflected light from the outer peripheral portion of the LPF 5. Therefore, the outer peripheral portion of the LPF 5 can be brought close to the effective light flux (the light receiving surface of the image pickup element). In other words, the LPF 5 can be made as small as possible, and the cost can be reduced.

Further, since the positioning of the LPF 5 in the vertical and horizontal directions is performed by the base plate 3 having the highest positional accuracy, it is not necessary to make a large margin of the effective portion of the LPF 5 with respect to the effective luminous flux, and the LPF 5 can also be used in this respect. It is possible to reduce the price as much as possible.

[0042]

As described above, according to the present invention,
Since the holding member holding the low-pass filter is held by pressing the cover glass of the image sensor package with a spring via the sheet-shaped spacer, the low-pass filter is held in a small space (thinness). Therefore, it can be applied to an image pickup apparatus using a large image pickup element.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a solid-state imaging unit of a digital camera to which the present invention has been applied.

FIG. 2 is a perspective view showing a state where a CCD package is adhered to a CCD plate.

FIG. 3 is a perspective view showing a CCD unit.

FIG. 4 is an exploded perspective view of an LPF unit.

FIG. 5 is an explanatory diagram for explaining a method of joining the LPF unit and the CCD unit.

FIG. 6 is an explanatory diagram for explaining a method of attaching the LPF unit to the CCD unit.

FIG. 7 is a perspective view showing a solid-state imaging unit in a completed state.

FIG. 8 is a side view showing the solid-state imaging unit in a completed state.

FIG. 9 is a top view showing the solid-state imaging unit in a completed state.

FIG. 10 is a diagram for explaining an LPF positioning method.

FIG. 11 is a central cross-sectional view of a solid-state imaging unit.

[Explanation of symbols]

1: CCD plate 2: CCD package 3: Base plate 4: LPF spacer 5: LPF 6: LPF frame 7: LPF cover plate 7c, 7d, 7e, 7f: Claw portion of LPF cover plate 8a, 8b: LPF presser spring 10: CCD unit 11: LPF unit

Claims (16)

[Claims] 1. An image pickup apparatus in which a lowpass filter is arranged in the vicinity of an image pickup element, wherein a holding member holding the lowpass filter is biased by a spring against a cover glass of the image pickup element package via a sheet-shaped spacer. An imaging device characterized by holding. 2. The image pickup apparatus according to claim 1, wherein the holding member includes a frame into which the low-pass filter is directly fitted and a cover member that covers the frame. 3. The image pickup apparatus according to claim 1, wherein the cover member is formed with a window smaller than the low-pass filter. 4. The spring is formed of a leaf spring, and a claw portion is erected on the cover member, and the leaf spring is configured to attach the cover member to the cover glass of the image pickup device package via the claw portion. 5. The method according to claim 1, further comprising:
The imaging device according to any one of items 1 to 5. 5. The image pickup apparatus according to claim 4, wherein the leaf spring and the cover member are made of a conductive member and are grounded. 6. A space smaller than the low pass filter is formed in the spacer, and a closed space is formed between the low pass filter and the cover glass. The imaging device according to any one of 5 above. 7. The image pickup apparatus according to claim 1, wherein positioning of the holding member in a direction perpendicular to the optical axis is performed by a base member holding the image pickup element package. . 8. The image pickup apparatus according to claim 1, wherein the low-pass filter is smaller than a cover glass of the image pickup element package. 9. A holding mechanism for a low-pass filter arranged in the vicinity of an image sensor, wherein a holding member holding the low-pass filter is biased by a spring against a cover glass of the image sensor package via a sheet-shaped spacer. A holding mechanism for a low-pass filter, which is characterized in that the holding mechanism is used. 10. The holding mechanism for a low-pass filter according to claim 9, wherein the holding member includes a frame into which the low-pass filter is directly fitted and a cover member that covers the frame. 11. The holding mechanism for a low-pass filter according to claim 9, wherein the cover member has a window smaller than the low-pass filter. 12. The spring is formed of a leaf spring, and a claw portion is provided upright on the cover member, and the leaf spring is configured to attach the cover member to the cover glass of the image pickup device package via the claw portion. 9. The method according to claim 9, further comprising:
11. The low-pass filter holding mechanism according to any one of 11 above. 13. The holding mechanism for a low-pass filter according to claim 12, wherein the leaf spring and the cover member are made of a conductive member and are grounded. 14. A space smaller than the low pass filter is formed in the spacer, and a closed space is formed between the low pass filter and the cover glass. The holding mechanism for the low-pass filter according to any one of 13 above. 15. The base member for holding the image pickup device package positions the holding member in a direction perpendicular to the optical axis.
A holding mechanism for the low-pass filter according to any one of 4 above. 16. The holding mechanism for a low pass filter according to claim 9, wherein the low pass filter is smaller than the cover glass of the image pickup device package.