Radiant energy – Photocells; circuits and apparatus – Photocell controlled circuit
Reexamination Certificate
1998-12-18
2001-02-06
Lee, John R. (Department: 2878)
Radiant energy
Photocells; circuits and apparatus
Photocell controlled circuit
C250S239000, C257S434000
Reexamination Certificate
active
06184514
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to covers for protecting image sensors, and more particularly, to a plastic cover for use in covering an area CCD array.
BACKGROUND OF THE INVENTION
A typical prior art sensor is provided in a supporting substrate such that the image sensor is positioned below the top surface of the substrate. The substrate includes a plurality of connecting leads which are used to electrically connect the image sensor to a circuit board as is done in the prior art with other electrical components. Typical image sensors are often area charge couple devices which are very expensive, sensitive to particles, and susceptible to damage. It is essential with CCDs to conduct preliminary tests on the image sensor prior to installation. Often, it is necessary to run a final test after the image sensor is installed in a product. In order to protect the CCD from particles and minimize any potential damage to the image sensor, a clear cover glass is usually placed directly over the substrate. The cover glass is typically provided with a fillet of epoxy placed around its perimeter. Image sensors are available to customers with permanent or temporary cover glass. Devices with permanent cover glass loses some light due to the reflection and transmission of the glass. The amount of light loss depends on the index of refraction of the glass material. In contrary, devices with temporary cover glass does not have this problem. Temporary cover glass is removed after testing and final installation of the image sensor. The substrate is bonded directly to the fiber bundle optics of the product allowing a very tight clearance between the lens optics and the CCD. Although, permanent-sealing covers loses more light than devices without covers, they provide a better moisture barrier and particle protection to the image sensor. It is up to the customer to decide whether a permanent or temporary cover will better fit their product. When it is desired to provide a permanent seal, then the epoxy side of the glass cover is placed directly against the top surface of the substrate. When it is desired to provide a temporary cover, then the covered glass is placed on the substrate such that the epoxy is facing upward and the tape is used to hold the cover glass to the substrate during testing. If it is desired to permanently retain the glass cover on the substrate, the cover must be cured in an oven which introduces additional cost and expense. When the cover glass is to be temporarily mounted to the substrate an adhesive tape is used to secure the cover glass to the substrate. However, the adhesive tape presents a problem in that it leaves a residue on the ceramic substrate. Additionally, the tape may also leave particles upon the substrate that could potentially fall on the top of the image sensor. In addition, the process of applying the tape in securing the cover glass can be a tedious and time consuming operation. A further problem with prior art cover glass is that when the temporary cover glass is secured onto the substrate, if it is damaged or the optical property is substantially reduced due to particles, there is relatively a tedious and expensive process to remove the temporary cover glass. Defects and particles on the CCD are detected during standard production test and final product test. If particles are found on devices with the temporary cover glass, then the lid must be removed in order to clean the particles. If the problem is fixed, then the temporary cover must be reattached to the substrate. However, if the cover glass is contaminated with particles or scratches, a new temporary cover must be used for the device.
Thus, there is a need to provide an improved temporary cover glass that is inexpensive, can be easily changed in the event of defects or particles, and/or may be easily removed after testing the sensor. It is also desirable to provide a process which minimizes the amount of labor necessary for providing of the cover glass.
SUMMARY OF THE INVENTION
The present invention is directed to overcoming one or more of the problems set forth above. Briefly summarized according to one aspect of the present invention, there is provided a cover for protecting an image sensor mounted on a supporting substrate, the substrate having a generally planer surface, the image sensor being mounted below the generally planer surface, the cover comprising:
a body extending over the image sensor and having means for removably mounting and demounting the cover from the substrate, the body having a window area such that use and/or test of said sensor may occur through said window when the cover is mounted to said substrate.
In accordance with another aspect of the present invention there is provided a sensor and cover assembly comprising sensor having a supporting substrate having a generally planer upper surface and an image sensor mounted to the substrate below the upper surface, and a cover for positioning on the upper surface for protection of the image sensor, the cover comprising:
a body extending over the image sensor and having means for removably mounting and demounting the cover from the substrate, the body having a window area such that use and/or test of said sensor may occur through said window when the cover is mounted to said substrate.
In accordance with yet another aspect of the present invention there is provide a method of testing an image sensor provided in a supporting substrate, comprising:
providing a supporting substrate having a general planer upper surface and an image sensor mounted to the supporting substrate below the upper surface;
providing a removable cover for engagement with the supporting substrate, the lid extending over the image sensor, the cover having a body having a window such that use and/or test of said sensor may occur through said window when the cover is mounted to said substrate; and
subjecting the image sensor to optical testing through the window.
The above, and other objects, advantages and novel features of the present invention will become more apparent from the accompanying detailed description thereof when considered in conjunction with the following drawings.
REFERENCES:
patent: 5310076 (1994-05-01), Burton et al.
patent: 5400915 (1995-03-01), Kennedy
patent: 5603410 (1997-02-01), Kara
patent: 5782370 (1998-07-01), Kamiya
patent: 5861654 (1999-01-01), Johnson
Arnold Craig E.
Harland Mark A.
Rezende Carlos F.
Eastman Kodak Company
Lee John R.
Pincelli Frank
Pyo Kevin
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