Active solid-state devices (e.g. – transistors – solid-state diode – Responsive to non-electrical signal – Electromagnetic or particle radiation
Reexamination Certificate
2000-10-19
2002-07-09
Le, Vu A. (Department: 2824)
Active solid-state devices (e.g., transistors, solid-state diode
Responsive to non-electrical signal
Electromagnetic or particle radiation
C257S433000, C257S480000, C438S057000, C438S069000, C438S070000
Reexamination Certificate
active
06417552
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a solid-state imaging device comprising a semiconducting imaging element with a radiation-sensitive surface, which imaging element is provided in a housing which is covered, at the side facing the radiation-sensitive surface, with a window of a transparent material which is attached to the envelope by means of an adhesive. For the semiconducting imaging element use can be made of, for example, a CCD imager or a CMOS imager, and said imaging element may be both linear and two-dimensional. Two-dimensional imagers are employed in cameras, for moving pictures (TV) as well as for still pictures (photography). Linear imagers are used, for example, as scanners in, for example, facsimile apparatus.
To protect the semiconducting imaging element against atmospheric influences, in particular moisture, it is encapsulated in a housing, for example, of a ceramic material which, on the side where the light is incident, is covered in an airtight manner by a glass window. As ordinary glass transmits infrared radiation (IR), this glass window is customarily provided with a filter, for example a coating, which blocks infrared radiation, thereby precluding that this radiation reaches the photosensitive imaging element.
A drawback of known housings resides in that the transmission characteristics of the glass window and hence the sensitivity of the imaging device is angle-dependent. It is an object of the invention to provide, inter alia, an imaging device which is not angle-dependent.
To achieve this, an imaging device of the type described in the opening paragraph is characterized in accordance with the invention in that the transparent material includes a layer of phosphorus glass.
SUMMARY OF THE INVENTION
The invention is based, inter alia, on the recognition that the angle dependence in the characteristics of the customary glass window is caused by the IR filter and that it can be precluded by using a type of glass which does not transmit infrared radiation, so that such a filter on the glass is not necessary.
In practice, it has been found that degradation at the joint between the ceramic housing and the window may occur, which degradation may even result in breakage of this joint in the course of time. A preferred embodiment of an imaging device in accordance with the invention, wherein this drawback is obviated entirely, or at least substantially entirely, is characterized in that at least the side of the window facing the radiation-sensitive surface is provided with a coating which improves the bond between the window and the ceramic housing and which leaves the part of the window via which an image is projected on the imaging element exposed. A specific embodiment is characterized in that the coating is provided in the form of a ring which extends along the edge of the window at the location where the window is attached to the ceramic housing. By providing the coating substantially at the edge of the glass cover, bonding problems are precluded while the transmission characteristics are not influenced by the coating.
For the coating use can be made of various materials. Very good results are achieved by using chromium.
These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.
REFERENCES:
patent: 5550398 (1996-08-01), Kocian et al.
patent: 5616949 (1997-04-01), Watanabe
patent: 5945721 (1999-08-01), Tatoh
patent: 0089044 (1983-09-01), None
patent: 9950917 (1999-10-01), None
Biren Steven R.
Le Vu A.
Wilson Christian D.
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