Image analysis – Image sensing
Reexamination Certificate
1998-12-23
2002-01-29
Grant, Jerome (Department: 2624)
Image analysis
Image sensing
C358S482000, C358S483000
Reexamination Certificate
active
06343162
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a contact type image sensor which reads an original from light reflected therefrom and can be used as an image pickup device of a facsimile, a copier, a scanner, and the like, and to an information processing apparatus using such a contact type image sensor.
2. Related Background Art
As an example of an original reader used with a facsimile, a copier, a scanner, or the like, a contact type image sensor is known which focusses an image of the original at a magnification factor of 1:1 and reads the image having the same size as the original with a sensor array. Such a contact type image sensor is constituted of: a sensor substrate formed with a plurality of sensor chips each having a plurality of pixels for photoelectric conversion and a protective film for protecting the sensor chips; a rod lens array for focussing an image of an original upon pixels of the sensor chips; and a cover glass defining an original reading surface, respectively mounted on a frame.
FIG. 15
is a schematic perspective view of a conventional contact type image sensor. Reference numeral
41
represents a frame for supporting the image sensor, and reference numeral
45
represents a transparent cover glass adapted to be in contact with an original and defining an original reading surface.
A plurality of optical sensors (pixels) are disposed along a longitudinal direction (main scan direction) DM of the frame
41
, the shorter side direction DS being a sub-scan direction.
FIGS. 16A
to
16
C are cross sectional views showing the structures of different image sensors taken along line
17
—
17
in FIG.
15
. Each image sensor shown in
FIGS. 16A
to
16
C is constituted of: a light source
3
for illuminating an original; a rod lens array
2
disposed directly under an original reading surface of a cover glass
1
; sensor chips
12
; and a sensor substrate
18
, respectively held in position by a frame
9
. The image sensor shown in
FIG. 16A
has a bottom plate
8
integrally mounted on the frame
9
via a spacer
6
. The image sensor shown in
FIG. 16C
has a transparent substrate
10
in place of the sensor substrate
18
. In the image sensors shown in
FIGS. 16A and 16B
, a sensor array
19
is constituted of the sensor substrate
18
and sensor chips
12
. A ceramic or glass epoxy substrate is used as the sensor substrate
18
. After the sensor chips
12
are disposed on the substrate
18
, wire bonding is performed to form the sensor array
19
. The configuration of the frame
9
and the processing of the sensor substrate
18
have been determined so as to prevent stray light to be caused by external light and internally reflected light from entering sensor light reception areas. Other necessary components are also used for the image sensors shown in
FIGS. 16A and 16B
.
In the contact type image sensor shown in
FIG. 16C
, in place of the sensor substrate
18
, the transparent substrate
10
such as a glass substrate with electrical wiring connections is used. The sensor array
19
is formed by mounting a plurality of face-down sensor chips
12
for photoelectric conversion in one line on the transparent substrate
10
. High work precision of the image sensor has been set in order to prevent stray light to be caused by external light and internally reflected light from entering sensor light reception areas, more than the sensor arrays shown in
FIGS. 16A and 16B
.
FIG. 17
shows another example of the contact type image sensor shown in
FIG. 15. A
focussing unit
47
is disposed in a first space
41
A of a frame
41
. The focussing unit
47
has side plates
72
and
73
which allow a lens array of one or more lenses
71
to be disposed in rows. A light source
46
is disposed in a second space
41
B. The light source
46
is constituted of: one or more LED light source units
63
; a light guide plate
61
for guiding light from the light source along the main scan direction DM and illuminating an original PP; and a housing
62
for intercepting leak light from the light guide plate
61
and positioning the light guide plate
61
to efficiently illuminate the original PP.
The first and second spaces
41
A and
41
B communicate with each other. A sensor array
43
is mounted on an electrical circuit substrate
44
and is disposed between the frame
41
and a frame
42
as a second support, facing a third space
41
C.
This image sensor is assembled in the following manner. The light source
46
is fixed to a mount plane
41
D with adhesive or screws, and the focussing unit
47
is inserted into the first space
41
A and fixed to a mount plane
41
E with adhesive or screws.
The electric circuit substrate
44
with the sensor array
43
is fixed to the frame
41
by using the frame
42
or by using adhesive or screws.
With the above-described contact type image sensors, as shown in
FIG. 18
, in order to intercept a stray light beam
31
entering from a gap between a lens array and a frame, a stray light beam
32
entering from the bottom of each LED, and stray light beams entering from the sides and bottom of a sensor substrate, light interception walls are mounted on the frame, a gap is minimized with strict size precision, or other countermeasures are adopted. Therefore, components become complicated and bulky so that the assembly performance is degraded. Manufacture cost becomes high because of an increase in the number of components such as a bottom plate and an internal reflection preventing process.
In the case of a contact type image sensor such as shown in
FIG. 16C
which is formed by mounting a plurality of face-down sensor chips for photoelectric conversion in one line on a transparent substrate such as a glass substrate with electrical wiring connections, the merits of the transparent substrate become demerits because of entrance of stray light.
In order to further enhance and promote the compact structure and highest merit of the above-described contact image sensor, the following technical issues to be solved still exist.
(1) As the focussing unit
47
shown in
FIG. 17
is made compact, the coating area of adhesive
49
for fixing the focussing unit
47
to the frame
41
becomes small. Therefore, it becomes difficult to coat the adhesive
49
, or the adhesive may permeate into the surface of the focussing lens
71
to block the focussing optical path so that light information of the original PP into the sensor array
43
is intercepted to thus lower the image quality.
(2) If there is a variation in assembly works of inserting the focussing unit into the first space
41
A and fixing it to the mount plane
41
E, a position displacement of the focussing unit
47
from the mount plane
41
E occurs so that the image quality is lowered.
SUMMARY OF THE INVENTION
An object of the present invention is to make compact a contact type image sensor. Another object of the invention is to improve an assembly performance of a contact type image sensor.
In order to achieve the above objects, according to one embodiment of the invention, there is provided a contact type image sensor comprising: a sensor substrate having photosensors mounted thereon; a focussing unit for focussing light from an original upon the photosensors; and a frame for holding the sensor substrate and the focussing unit, wherein the focussing unit abuts on the sensor substrate. With this embodiment, the contact type image sensor can be made compact.
According to another embodiment of the invention, there is provided a contact type image sensor comprising: photosensors; a support member for supporting an original; a focussing unit for focussing light from the original upon the photosensors; a frame for holding the photosensors, the focussing unit, and the transparent support member; and a focussing unit holding member disposed between the transparent support member and the focussing unit, for positioning the focussing unit relative to the frame. With this embodiment, the assembly works of the contact type image sensor become easy.
Other objects and
Nagata Kenji
Saito Oji
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