Active solid-state devices (e.g. – transistors – solid-state diode – Field effect device – Charge transfer device
Reexamination Certificate
2001-04-25
2003-04-29
Meier, Stephen D. (Department: 2822)
Active solid-state devices (e.g., transistors, solid-state diode
Field effect device
Charge transfer device
C257S224000, C257S227000
Reexamination Certificate
active
06555854
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a photosensitive device, and more particularly to a photosensitive device with multi-focus lengths.
2. Description of the Prior Art
Many kinds of devices exist for sensing color images. Theses devices can be desktop or hand held scanners, copying machines, facsimile machines and the like.
FIG. 1
shows a schematic cross-sectional view of a scanner head
11
inside the housing of a conventional reflective-type scanner
10
. During scanning, a light source
12
illuminates an original
13
, such as a document. The optical system comprised of a set of mirrors
14
and a lens assembly
15
directs the optical path of the reflective light from the original
13
and focuses it onto a photosensitive detector
16
.
The charge coupled device (CCD) is generally used as the photosensitive detector
16
.
FIG. 2A
is a schematic cross-sectional view of a conventional charge coupled device
20
in the longitudinal direction. In general, the charge coupled device
20
is comprised of a substrate
21
, an array of optical sensors
22
and a transparent glass plate
23
with a constant thickness. The array of the optical sensors
22
are disposed on the substrate
21
. The transparent glass plate
23
is disposed on the array of the optical sensors
22
served as a cover thereof to prevent being touched and dust.
FIG. 2B
is an enlarged schematic cross-sectional view of the charge coupled device
20
in the transverse direction, in which each optical sensor
22
is comprised of a R sensor element
221
, a G sensor element
222
and a B sensor element
223
. R, G and B herein respectively represent primary colors, red, green and blue.
In this conventional charge coupled device
20
, the optical sensor
22
is comprised of only a set of R, G, and B sensor elements (
221
,
222
,
223
). And, the transparent glass plate
23
used as the cover of the array of the optical sensors
22
is provided with a constant thickness and a certain refractive index. Thus, the focal length of this charge coupled device
20
is limited. The depth of focus of this charge coupled device
20
is also limited. Referring to
FIG. 1
, the focal length herein means the optical distance between the lens assembly
15
and the array of the optical sensors
22
of the charge coupled device
20
when the image of the original
13
is focused onto the optical sensors
22
. The depth of focus means the variable range of the focus length of the charge coupled device
20
. When the resolution for image capture of a scanning system becomes higher and higher, the depth of focus of the charge coupled device
20
is also narrowed. It is therefore more difficult to fulfill the requirement of the scanning system with various high resolutions by way of adjusting the positions of the mirrors
14
, the lens assembly
15
and the charge coupled device
20
.
Accordingly, it is an intention to provide a charge coupled device with multi-focus lengths to fill the demand of the scanning system with various high resolutions.
SUMMARY OF THE INVENTION
It is one objective of the present invention to provide a charge coupled device (CCD) with multi-focus lengths, in which a plurality of transparent plates are disposed on the arrays of optical sensors in parallel. Each of the transparent plates corresponds to one of the arrays of the optical sensors. By way of either of changing the thicknesses of the transparent plates and changing the position levels of the arrays of the optical sensors, each array of the optical sensors obtains a different focus length. And thus, the depth of focus of the present CCD is improved. On the other hand, the depth of field of the object with the image to be read out is also improved.
It is another objective of the present invention to provide a charge coupled device with multi-focus lengths, which improves the depth of focus of this device to fulfill demand of a scanning system for capturing one image with various high resolutions.
It is a further objective of the present invention to provide a charge coupled device with multi-focus lengths, which is easily manufactured and has low production cost.
It is still a further objective of the present invention to provide a charge coupled device with multi-focus lengths, which is applicable to a scanner, a facsimile machine, a copying machine and the like.
In order to achieve the above objectives of this invention, the present invention provides a charge coupled device with multi-focus lengths. The present charge coupled device comprises a substrate, a plurality of arrays of optical sensors and a plurality of transparent plates. The arrays of the optical sensors are disposed on the substrate. Each of the arrays has a plurality of the optical sensors and each of the optical sensors includes a R sensor element, a G sensor element and a B sensor element. Each of the transparent plates is provided with a respective thickness and disposed on one of the arrays of the optical sensors. By means of the arrangement of the transparent plates with different thicknesses in parallel disposed on the arrays of the optical sensors, each of the arrays of the optical sensors obtains a different focus length. Therefore, the depth of focus of the present charge coupled device is improved. On the other hand, the depth of field of the object with the image to be read out is improved.
REFERENCES:
patent: 5118924 (1992-06-01), Mehra et al.
Huang Chih-Wen
Huang Yin-Chun
Meier Stephen D.
Umax Data Systems Inc.
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