Optical: systems and elements – Lens – With support
Reexamination Certificate
2001-10-25
2003-06-03
Mack, Ricky (Department: 2873)
Optical: systems and elements
Lens
With support
Reexamination Certificate
active
06574054
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a structural unit and a method of fixing a lens that forms an optical image and a solid state imaging element that photo-electrically converts the optical image into electrical signals, and in particular relates to a structural unit and a method of fixing a lens and a solid state imaging element, which require a relatively high accuracy in fixing of the lens and the solid state imaging element and which require an adjustment in positioning thereof.
2. Discussion of the Background
In image reading apparatuses that read an image as an optical image using a lens and a solid state imaging element such as a CCD (charge-coupled device), the solid state imaging element (hereinafter sometimes referred to as a CCD) must be precisely placed at a position where a line image is formed by the lens. That is, for precisely reading an image with predetermined optical characteristics of the lens (e.g., focusing, magnification characteristics, etc.), precise adjustment of the relative position of the lens and the CCD is required. At the same time, it is necessary to fix each of the lens and the CCD with relatively high accuracy with minimal positional deviation, after adjustment of respective positions of the lens and the CCD.
Conventionally, screws have been used in fixing a CCD and a lens. When screws are used in fixing a CCD and a lens, generally, positional deviation of from several hundreds mm to several tens &mgr;m is observed in the position of the CCD relative to the lens.
Japanese Patent Laid-open Publication No. 5-328017 describes a method of using a relatively complicated mechanism including an arrowhead, a ball, a spring, etc., instead of screws. The number of parts of the mechanism is relatively large and consequently the cost of the mechanism is relatively high.
Therefore, recently, a method of using an adhesive agent has been attempted for fixing a CCD and a lens, in which positional deviation with respect to the CCD and the lens and the number of parts used in fixing are relatively small as compared with the method of using screws in fixing the lens and the CCD.
As a method of fixing a CCD and a lens with an adhesive agent, a method referred to as filling bonding is known, as described for example in Japanese Patent Laid-open Publication No. 7-297993.
In the filling bonding method, a gap greater than an adjusting margin for positional adjustment is provided between members to be bonded, and an adhesive agent is filled in the gap so that the members are bonded together with the adhesive agent. In the method, the amount of the gap is set such that the members to be bonded together will not contact each other even when the shapes of the members are varied from the designed shapes. For the adhesive agent, an adhesive material that becomes rigid by ultraviolet light in a short time, about 5 seconds, is used to provide high productivity.
However, the volume contraction percentage of an adhesive agent that becomes rigid by ultraviolet light when the adhesive agent becomes rigid is generally about from 5% to 10%. If the volume contraction percentage is 7%, when the shape of the hardened adhesive agent is a cube, the cube-shaped adhesive agent contracts about 2% in each of the three-dimensional directions thereof. Accordingly, in the filling bonding method, when the thickness of the adhesive agent for bonding members to be bonded together is relatively large, for example, about 1 mm, contraction of about 2%, i.e., a positional deviation of about 20 &mgr;m, occurs in each of the three dimensional directions. This contraction causes a positional deviation in the members to be bonded together when the members are fixed. Thus, the filling bonding method cannot be applied in fixing a CCD and a lens in a CCD lens unit that requires a relatively high accuracy, e.g., a positional deviation of about 20 &mgr;m or smaller, in fixing the CCD and the lens.
Japanese Patent Laid-open Publication No. 10-309801 describes a method that realizes a relatively high accuracy in fixing members using an adhesive agent. JP No. 10-309801 relates to a structure to mount an ink jet printing head to a head supporting member with high accuracy. In the mounting structure, an intermediary mounting member is arranged between the ink jet printing head and the head supporting member, and the intermediary supporting member is fixed to the ink jet printing head by an adhesive agent, and at the same time, to the head supporting member as well via the adhesive agent.
In the above-described structure, the volume contraction of an adhesive agent occurring when the adhesive agent is hardened is converted only to a movement of the intermediary support member to be attached by the adhesive agent, so that positional deviation in other parts, e.g., in the ink jet printing head, is avoided.
The applicant of the present invention has previously proposed to apply the above-described structure of JP No. 10-309801 to a CCD lens unit including a CCD and a lens, in which the CCD and a CCD supporting member are bonded together via an intermediary supporting member. The number of parts in the proposed CCD lens unit is small as compared with the mechanism of JP No. 5-328017 including an arrowhead, etc. However, besides the CCD and the lens, parts for supporting or fixing the CCD and the lens are still needed, such as the intermediary supporting member for supporting the CCD, a lens housing tube for housing and supporting the lens and a pressing plate for fixing the tube, and a supporting member for supporting the intermediary supporting member and the lens housing tube.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above-discussed and other problems and addresses the above-discussed and other problems.
Preferred embodiments of the present invention provide a novel structural unit and a method for fixing a solid state imaging element and a lens, which realize a relatively high accuracy in fixing the solid state imaging element and the lens and at the same time realizes a significant reduction in the number of parts used in fixing the solid state imaging element and the lens.
Other preferred embodiments of the present invention provide a structural unit for fixing a solid state imaging element and a lens, in which the positional adjustment with respect to the solid state imaging element and the lens can be performed in 5 axial directions.
According to a preferred embodiment of the present invention, a structural unit includes a lens that forms an optical image, a solid state imaging element placed in a predetermined position relative to the lens, and an intermediary supporting member that may be bonded and fixed to each of the lens and the solid state imaging element by an adhesive so that the lens and the solid state imaging element are integrated with each other in a state that a positional relation between the lens and the solid state imaging element is maintained. In this configuration, because the intermediary supporting member is bonded and fixed to each of the lens and the solid state imaging element by the adhesive so that the lens and the solid state imaging element are integrated with each other in a state that a positional relation between the lens and the solid state imaging element is maintained, the effect of contracting of the adhesive when the adhesive is hardened is absorbed by the movement of the intermediary member, so that the lens and the solid state imaging element are fixed with relatively high accuracy. Further, by bonding each of the lens and the solid state imaging element to the intermediary supporting member, various parts that are generally required for fixing the solid state imaging element and the lens, e.g., a lens supporting member, a lens housing tube, a lens pressing plate, and screws for fastening the pressing plate, etc., which are used in some background structural units, are not required.
The unit may further include a mounting part provided to one of the lens and the solid state imaging el
Hirai Ryohji
Morii Yoshihiro
Mack Ricky
Ricoh & Company, Ltd.
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