Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
1999-08-03
2002-11-19
Sikes, William L. (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S149000, C349S058000, C250S208100
Reexamination Certificate
active
06483567
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image processing device and, more particularly, to an image processing device such as an optical sensor, liquid crystal display, or plasma display for reading or displaying image information.
2. Related Background Art
An X-ray examination apparatus used in the medical field employs, as a mainstream, a scheme of converting an X-ray into visible light by a fluorescent plate and exposing a film in contact with the fluorescent plate to the light for confirmation because a morbid portion of a patient must be accurately detected. In fact, the following problems are pointed out in association with this confirmation method: it takes a time from measurement to diagnosis although the resolution of an image has no problem for practical use, and specifying a measurement position (e.g., morbid portion) greatly depends on the skill and intuition of the technician.
In recent years, large area sensors using amorphous silicon diodes have been developed and increased in their reliability. When amorphous silicon is used, the area can be easily increased. Along with this advantage, an urgent demand has arisen for developing a device for increasing the efficiency of the conventional X-ray examination for diagnosing a morbid portion of a patient by using an emphasized image processed in real time. To largely change the panel formation process size at once to achieve a large area sensor, new investment for plants and equipment for the film formation and photo-process is impractically required. Hence, actually, a plurality of panels having an existing process size are two-dimensionally bonded in accordance with the pixel pitch.
FIG. 1
is a schematic sectional view showing an X-ray sensor manufactured by bonding. Referring to
FIG. 1
, each sensor panel
301
comprises a board made of non-alkali glass or the like. A base
302
fixes four sensor panels
301
at predetermined positions and has an X-ray absorption lead member for protecting an electrical mounted portion on the lower surface. A first bonding layer
303
bonds the sensor panels
301
to the base
302
. A fluorescent plate
305
serves as a wavelength conversion member for converting an X-ray into visible light. A gel-like second bonding layer
304
bonds the fluorescent plate
305
to the sensor panels
301
. Printed circuit boards
307
electrically drive the sensor panels
301
, respectively. Flexible wiring boards
306
connect the printed circuit boards
307
to the sensor panels
301
, respectively. The members
301
to
307
form an X-ray sensor portion
330
.
The X-ray sensor also has a case
320
, a lid
321
, a cover
323
formed from, e.g., lead to protect the electrical mounted portion, legs
324
for fixing the printed circuit boards
307
, and angles
325
for fixing the base
302
to the case
320
. The members
320
to
325
form a chassis portion
340
. The X-ray sensor unit is formed by fixing the X-ray sensor portion
330
in the chassis portion
340
.
An X-ray incident from the upper side in
FIG. 1
as image information is converted into a visible light wavelength by the fluorescent plate
305
, transmitted through the transparent second bonding layer
304
, and is incident on optical sensor elements (photoelectric conversion elements) two-dimensionally arrayed on the upper surface of each sensor panel. The incident light is converted into an electrical signal by the optical sensor elements and converted into image information by the printed circuit boards
307
through the flexible wiring boards
306
, so the X-ray sensor functions as a two-dimensional X-ray sensor.
A technical point that must be taken into consideration in selecting the structure of such a two-dimensional X-ray sensor is that the four sensor panels need be accurately aligned relative to each other in the planar direction to ensure a high resistance to mechanical impact in bonding the fluorescent plate because of the small pixel pitch. Usually, for the first bonding layer
303
, a silicone-based cold-setting adhesive, which rarely expands/shrinks in hardening and has a strong adhesion and elasticity after hardening is used.
A normal temperature guarantee range of an X-ray sensor is −30° C. to +50° C. The technical problem described in the prior art must be solved within this temperature range. However, in this structure, since the thermal expansion coefficient of the sensor panel
301
as 4.7×10
−6
/° C. and that of the base
302
as 2.9×10
−5
/° C. have a large difference (this difference normally appears in use of the above-described materials), and therefore, the difference in expansion/shrinkage due to the temperature difference of 80° C. is as large as 617%. When the outer size of each sensor panel
301
is 250 mm, the expansion/shrinkage difference of 486 &mgr;m directly appears as a pixel pitch shift because of the elastic force of the adhesive
303
. When the pixel pitch of the X-ray sensor is 160 &mgr;m, this shift amount cannot be neglected. In addition, when the sensor panel
301
and base
302
have the same thickness in terms of mechanical strength, they largely warp. When the base
302
has a sufficient thickness in terms of mechanical strength with respect to the sensor panel
301
, large internal stress is generated in the sensor panel to degrade the characteristics of the element and also peel the adhesive
303
. This tendency becomes conspicuous as the screen size increases.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a structure for suppressing a pitch shift between bonded sensor panels or opposing panels particularly in an image processing device having a large screen even when the temperature changes.
It is another object of the present invention to provide a structure for suppressing warp, internal stress, and peeling in bonded panels.
It is still another object of the present invention to provide an inexpensive image processing device having excellent cost performance and an arrangement capable of facilitating selection of materials to be used and proper design and shortening the development period.
It is still another object of the present invention to provide an image processing device having at least one first board having a thermal expansion coefficient a and a plurality of semiconductor elements or/and wiring lines at an equal pitch P, and a second board having a thermal expansion coefficient b and opposing and bonded to the first board through bonding means,
wherein letting L be a length of the first board in a direction of array of the semiconductor elements or/and the wiring lines on the first board opposing the second board and T be a width of a temperature guarantee range of the image processing device,
−
P
/2
<LT
(
a−b
)<
P
/2
is satisfied.
According to the present invention, even when the temperature changes, the pixel pitch shift between the first panel and second panel which oppose and are bonded to each other or relative pixel pitch shift between the plurality of first panels can be prevented or minimized. In addition, warp or internal stress can be suppressed, and peeling can be prevented.
According to the present invention, a design concept capable of preventing or avoiding problems posed by a change in temperature due to a change in use conditions or the like can be provided.
According to the present invention, an image processing device which can be designed in a shorter developing period and has more excellent cost performance because materials to be used can be appropriately selected in accordance with the required performance and cost can be provided.
REFERENCES:
patent: 4558510 (1985-12-01), Tani et al.
patent: 5528403 (1996-06-01), Kawaguchi et al.
patent: 5707749 (1998-01-01), Katagiri et al.
patent: 6323891 (2001-11-01), Kitani et al.
Canon Kabushiki Kaisha
Duong Tai V.
Fitzpatrick ,Cella, Harper & Scinto
Sikes William L.
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