U.S. patent application number 09/940796 was filed with the patent office on 2002-01-17 for tiled imaging apparatus providing substantially continuous imaging.
This patent application is currently assigned to SIMAGE OY. Invention is credited to Schulman, Tom Gunnar.
Application Number | 20020006236 09/940796 |
Document ID | / |
Family ID | 10796769 |
Filed Date | 2002-01-17 |
United States Patent
Application |
20020006236 |
Kind Code |
A1 |
Schulman, Tom Gunnar |
January 17, 2002 |
Tiled imaging apparatus providing substantially continuous
imaging
Abstract
An imaging apparatus includes a plurality of imaging device
tiles arranged on an imaging support. Each of the imaging device
tiles includes an imaging device having an imaging surface and a
non-active region, wherein the imaging surface of a first imaging
device tile at least partially overlies the non-active region of a
second imaging device tile.
Inventors: |
Schulman, Tom Gunnar;
(Masala, FI) |
Correspondence
Address: |
KENYON & KENYON
1500 K STREET, N.W., SUITE 700
WASHINGTON
DC
20005
US
|
Assignee: |
SIMAGE OY
Espoo
FI
|
Family ID: |
10796769 |
Appl. No.: |
09/940796 |
Filed: |
August 29, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09940796 |
Aug 29, 2001 |
|
|
|
08890936 |
Jul 10, 1997 |
|
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Current U.S.
Class: |
382/312 ;
348/E3.032; 348/E5.027; 348/E5.086 |
Current CPC
Class: |
H04N 5/3415 20130101;
H04N 5/32 20130101; H04N 5/2253 20130101; H01L 27/14601
20130101 |
Class at
Publication: |
382/312 |
International
Class: |
G06K 009/20; G06K
007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 11, 1996 |
GB |
9614620.4 |
Claims
What is claimed is:
1. An imaging device tile for an imaging apparatus having an
imaging support, said imaging device tile comprising an imaging
device including a plurality of pixels and with an imaging surface
and a non-active region, a mount with a mounting surface, and an
imaging device support structure, said imaging device support
structure being arranged to position said imaging surface at an
angle to said mounting surface.
2. The imaging device tile of claim 1, wherein said imaging device
support structure is arranged between said imaging device and said
mount.
3. The imaging device tile of claim 2, wherein said imaging device
support structure is wedge-shaped.
4. The imaging device tile of claim 1, wherein said mount is
planar.
5. The imaging device tile of claim 1, wherein said imaging device
is planar.
6. The imaging device tile of claim 1, wherein said imaging device
includes a planar detector layer overlying a planar image readout
layer, said detector layer having a surface forming said imaging
surface.
7. The imaging device tile of claim 6, wherein said detector layer
comprises a plurality of image detector cells and said image
readout layer comprises a plurality of readout circuits, each of
said readout circuits being coupled to a corresponding one of said
image detector cells.
8. The imaging device tile of claim 7, wherein said detector layer
is substantially rectangular, said image readout layer is
substantially rectangular and further comprises a connection region
extending beyond said detector layer at an end thereof, said mount
is substantially rectangular and has a connection region extending
beyond said image readout layer at an end thereof, and wired
connections are provided between said connection regions of said
image readout layer and said mount, said non-active region of said
imaging device tile comprising said connection regions of said
image readout layer and said mount.
9. The imaging device tile of claim 1, further comprising a means
for mounting said imaging device tile at a tile mounting location
of said imaging support in a non-destructive, removable manner.
10. The imaging device tile of claim 1, wherein said imaging device
comprises a pixel semiconductor imaging device.
11. An imaging device tile for an imaging apparatus having an
imaging support, said imaging device tile comprising an imaging
device, said imaging device including a plurality of pixels and
with an imaging surface and a non-active region, a mount with a
mounting surface, and an imaging device support structure, said
imaging device support structure being arranged between said
imaging device and said mount to position said imaging surface at
an angle to said mounting surface.
12. An imaging apparatus comprising a plurality of imaging device
tiles arranged on an imaging support, each of said imaging device
tiles including an imaging device comprising a plurality of pixels
and having an imaging surface and a non-active region, wherein the
imaging device of a first imaging device tile at least partially
overlies the non-active region of a second imaging device tile
without overlying an active image region of the imaging device of
said second imaging device tile, each tile further comprising a
mount having a mounting surface for mounting a tile on said imaging
support.
13. An imaging support for an imaging apparatus, said imaging
apparatus having a plurality of imaging device tiles arranged on
said imaging support, wherein each of said imaging device tiles
includes an imaging device comprising a plurality of pixels and
having an imaging surface on a non-active region, the imaging
device of a first imaging device tile at least partially overlying
the non-active region of a second imaging device tile without
overlying an active image region of the imaging surface of the
imaging device of said second imaging device tile, said imaging
support comprising a support surface with a plurality of tile
mounting locations corresponding to said plurality of the imaging
device tiles, and further comprising an arrangement for mounting
said imaging device tiles at said tile mounting locations in a
non-destructive, removable manner, said tile mounting locations
being tilted to provide sawtooth deviations from said support
surface.
14. An imaging apparatus comprising a plurality of imaging device
tiles arranged on an imaging support, each of said imaging device
tiles including an imaging device comprising a plurality of pixels
and having an imaging surface and a non-active region proximate an
edge of said tile, said imaging device on said imaging device tile
being mounted on said imaging support in a tilted orientation,
wherein the imaging device of a first imaging device tile at least
partially overlies the non-active region of a second imaging device
tile without overlying an active image region of the imaging
surface of the imaging device of said second imaging device tile,
each tile further comprising a mount having a mounting surface for
mounting a tile on said imaging support.
15. An imaging apparatus comprising a plurality of imaging device
tiles arranged on an imaging support, each of said imaging device
tiles including an imaging device, said imaging device comprising a
plurality of pixels and having an imaging surface and a non-active
region, the imaging device of a first imaging device tile at least
partially overlying the non-active region of a second imaging
device tile without overlying an active image region of the imaging
surface of the imaging device of said second imaging device tile,
each tile further comprising a mount having a mounting surface for
mounting a tile on said imaging support, there being provided a
device support structure arranged between said imaging device and
said mounting surface to tilt said imaging device with respect to
said mounting surface.
16. An imaging support for an imaging apparatus, said imaging
apparatus having a plurality of imaging device tiles arranged on
said imaging support, each of said imaging device tiles including
an imaging device, said imaging device comprising a plurality of
pixels and having an imaging surface and non-active region, the
imaging device of a first imaging device tile at least partially
overlying the non-active region of a second imaging device tile
without overlying an active image region of the imaging surface of
the imaging device of said second imaging device tile, said imaging
support comprising a support surface with a plurality of tile
mounting locations corresponding to said plurality of imaging
device tiles, and further comprising an arrangement for mounting
said imaging device tiles at said tile mounting locations in
non-destructive, removable manner, said tile mounting locations
being tilted to provide sawtooth deviations from said support
surface.
17. An imaging apparatus comprising a plurality of imaging device
tiles arranged on an imaging support, each of said device tiles
including an imaging device, said imaging device comprising a
plurality of pixels and having an imaging surface and a non-active
region proximate at an edge of said tile, said imaging device on
said imaging device tile being mounted on said imaging support in a
titled orientation, the imaging device of a first imaging device
tile at least partially overlying the non-active region of a second
imaging device tile without overlying an active image region of the
imaging surface of the imaging device of said second imaging device
tile, each tile further comprising a mount having a mounting
surface for mounting a tile on said imaging support, and an imaging
device support structure arranged between said imaging device and
said mount for providing said tilted orientation.
18. An imaging apparatus comprising a plurality of imaging device
tiles arranged on an imaging support, each of said imaging device
tiles including an imaging device comprising a plurality of pixels
and having an imaging and a non-active region, wherein the imaging
device of a first imaging device tile at least partially overlies
the non-active region of a second imaging device tile without the
non-active region of the first imaging device tile overlying the
imaging surface of the imaging device of said second imaging device
tile, each tile further comprising a mount having a mounting
surface of mounting a tile on said imaging support.
19. An imaging support for an imaging apparatus, said imaging
apparatus having a plurality of imaging device tiles arranged on
said imaging support, wherein each of said imaging device tiles
includes an imaging device comprising a plurality of pixels and
having an imaging surface on a non-active region, the imaging
device of a first imaging device tile at least partially overlying
the non-active region of a second imaging device tile without the
non-active region of the first imaging device tile overlying the
imaging surface of the imaging device of said second imaging device
of said second imaging device tile, said imaging support comprising
a support surface with a plurality of tile mounting locations
corresponding to said plurality of imaging device tiles, and
further comprising an arrangement for mounting said imaging device
tiles at said tile mounting locations in a non-destructive,
removable manner, said tile mounting locations being tilted to
provide sawtooth deviations from support surface.
20. An imaging apparatus comprising a plurality of imaging device
tiles arranged on an imaging support, each of said imaging device
tiles including an imaging device comprising a plurality of pixels
and having an imaging surface and a non-active region proximate an
edge of said tile, said imaging device on said imaging device tile
being mounted on said imaging support in a tilted orientation,
wherein the imaging device of a first imaging device tile at least
partially overlies the non-active region of a second imaging device
tile without the non-active region of the first imaging device tile
overlying the imaging surface of the imaging device of said second
imaging device tile, each tile further comprising a mount having a
mounting surface for mounting a tile on said imaging support.
21. An imaging apparatus comprising a plurality of imaging device
tiles arranged on an imaging support, each of said imaging device
tiles including an imaging device, said imaging device comprising a
plurality of pixels and having an imaging surface and a non-active
region, the imaging device of a first imaging device tile at least
partially overlying the non-active region of a second imaging
device tile without the non-active region of the first imaging
device tile overlying the imaging surface of the imaging device of
said second imaging device tile, each tile further comprising a
mount having a mounting surface for mounting a tile on said imaging
support, there being provided a device support structure arranged
between said imaging device and said mounting surface to tilt said
imaging device with respect to said mounting surface.
22. An imaging support for an imaging apparatus, said imaging
apparatus having a plurality of imaging device tiles arranged on
said imaging support, each of said imaging device tiles including
an imaging device, said imaging device comprising a plurality of
pixels and having an imaging surface and a non-active region, the
imaging device of a first imaging device tile at least partially
overlying the non-active region of a second imaging device tile
without the non-active region of the first imaging device tile
overlying the imaging surface of the imaging device of said second
imaging device tile, said imaging support comprising a support
surface with a plurality of tile mounting locations corresponding
to said plurality of imaging device tiles, and further comprising
an arrangement for mounting said imaging device tiles at said tile
mounting locations in a non-destructive, removable manner, said
tile mounting locations being tilted to provide sawtooth deviations
from said support surface.
23. An imaging apparatus comprising a plurality of imaging device
tiles arranged on an imaging support, each of said imaging device
tiles including an imaging device, said imaging device comprising a
plurality of pixels and having an imaging surface and a non-active
region proximate at an edge of said tile, said imaging device on
said imaging device tile being mounted on said imaging support in a
tilted orientation, the imaging device of a first imaging device
tile at least partially overlying the non-active region of a second
imaging device tile without the non-active region of the first
imaging device tile overlying the imaging surface of the imaging
device of said second imaging device tile, each tile further
comprising a mount having a mounting surface for mounting a tile on
said imaging support, and an imaging device support structure
arranged between said imaging device and said mount for providing
said tilted orientation.
Description
[0001] This is a continuation of application Ser. No. 08/890,936
filed Jul. 10, 1997.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The invention relates to the field of imaging, an in
particular to apparatus for large area imaging.
[0004] 2. Description of the Art
[0005] Imaging systems are used in a wide range of applications,
particularly for imaging for medical diagnosis, in biotechnology,
and in industrial applications for non-destructive testing and
on-line product quality control. For all of these fields of
application, the prevailing means of performing imaging has been to
use radiation, usually X-rays, gamma-rays and beta-rays. Radiation
is detected by some sort of imaging plane, which need not be
planar. Accordingly, the term imaging surface will be used
hereinafter. Images are formed either directly on the imaging
surfaces (e.g., projection imaging) or data are processed and
images are reconstructed in a computer (e.g., computerized
tomography or coded aperture imaging in nuclear medicine).
[0006] Traditionally, the imaging surface was formed by a film in a
cassette. Other imaging surface solutions have been developed over
the past 40 years offering digital imaging. Such examples are NaI
scintillating screens, NaI scintillating crystals, BGO crystals,
wire gas chambers, digital imaging plates etc. More recently,
semiconductor imaging solutions such as Charged Coupled Devices
(CCDs), Si microstrip detectors and semiconductor pixel detectors
have been developed.
[0007] Typically, in all of the above cases, when a large imaging
area is needed it is made either as a monolithic structure (e.g.,
films, digital imaging plates, NaI screens, etc.) or as a mosaic of
smaller pieces (tiles) put together and fixed on a support surface
(e.g., gamma cameras with NaI crystals). When a monolithic large
imaging surface is employed, if a part of the surface is defective
then the whole surface needs to be changed. Unfortunately, the most
precise digital on-line imaging devices proposed so far involve
pixel-based semiconductors which cannot be manufactured in large
areas (larger than a few square cm at most). Moreover, it would not
be desirable to manufacture, for example, a monolithic 30 cm by 30
cm digital imaging semiconductor surface because the yield would be
low. If a portion of the expensive imaging area became defective,
then the whole surface would have to be replaced.
[0008] It has been proposed to provide a large area imaging surface
(larger than a few square mm) using a tiling approach. The
applicant's own patent application WO 95/33332 proposes such an
approach. Using such an approach, individual imaging devices are
arranged in an array, or mosaic, on an imaging support to form a
large area imaging mosaic. Outputs from the individual imaging
devices can be processed to provide a single output image
corresponding substantially to the whole area covered by the
imaging surface. However, when the imaging devices are tiled to
form such a mosaic, dead spaces are left around the active imaging
areas of the imaging devices. In order to deal with this problem it
is proposed to stagger adjacent rows of imaging devices in the
array and to provide for relative movement between an object to be
imaged and the imaging array. Although such an approach does give
good results and means that the effect of the dead spaces can be at
least substantially eliminated, this does require the provision of
a mechanism for the relative movement and appropriate software for
processing the resultant multi-exposure image.
[0009] There is thus a need for an improved imaging system and
method which, while providing the advantages of the tiling
approach, remove or at least mitigate the problems of previous
tiling approaches.
SUMMARY OF THE INVENTION
[0010] According to embodiments of the present invention, an
imaging apparatus includes an imaging support and a plurality of
imaging device tiles. Each tile includes an imaging device having
an imaging surface and has a non-active region at or adjacent an
edge of the tile. The imaging device on the tile mounted on the
support may be tilted, or angled, such that part of the imaging
surface of one tile at least partially overlies the non-active
region of another tile, thereby providing substantially continuous
imaging in a first direction. Such embodiments provide a new
imaging mosaic system for producing imaging mosaics using a
plurality of imaging devices tiles and an imaging support in a
manner which reduces or substantially eliminates the dead spaces
between tiles.
[0011] According to one particular embodiment, which enables the
use of a planar support, each tile includes a mount having a
mounting surface for mounting the tile on the support and a device
support structure for carrying the imaging device on the mount such
that the imaging surface is tilted with respect to the mounting
surface. The support structure may be an intermediate member
between the imaging device and the mount, and may be wedge-shaped
to fully support the imaging device. However, alternatives are
possible, for example spacers at one end of the tile.
[0012] In an alternate embodiment directed to the use of planar
tiles, each tile includes a mount having a mounting surface for
mounting the tile on the support. The support provides a plurality
of respective tile mounting locations on a support surface, the
mounting locations being tilted to provide sawtooth deviations from
the support surface. The imaging surface of each imaging device may
thus be tilted with respect to the support surface.
[0013] The mount in such embodiments may be planar, and may be
implemented using, for example, a printed circuit board. The
imaging devices may also be planar, and may include, for example, a
planar detector layer overlying a planar image readout layer, a
surface of the detector layer forming the imaging surface. The
detector layer can provide a plurality of detector cells and the
readout layer can provide a plurality of corresponding readout
circuits, each readout circuit being coupled to a respective
detector cell. In a particular embodiment, the detector layer is
substantially rectangular, the readout layer is substantially
rectangular and has a connection region which extends beyond the
detector layer at one end thereof, the mount is substantially
rectangular and has a connection region which extends beyond the
readout layer at the one end, wired connections are provided
between the connection regions of the readout layer and the mount,
and the non-active region of the tile comprises the connection
regions of the readout layer and the mount. The tile may be
elongated in the first direction (i.e., the direction of
substantially continuous imaging) to minimize the angle of tilt and
any effects of parallax. Moreover, the tiles may be mounted on the
support such that the detector layers of adjacent tiles extend in a
second direction perpendicular to the first direction so as to
almost or actually touch each other.
[0014] The imaging devices may be positioned and held on the
support in a reversible and non-destructive manner. For example, an
arrangement for mounting the imaging devices may allow individual
imaging devices to be removed multiple times so that the same
imaging device can be used in a different imaging support or it can
be replaced if found to be defective without damaging the imaging
support and without affecting the operation of any other imaging
device on the imaging support. The support may provide a plurality
of tile mounting locations, with the mounting arrangement removably
mounting a respective tile at each location.
[0015] According to another particular embodiment, each tile
mounting location may include a plurality of support contacts, each
for co-operating with a respective tile contact for a transfer of
signals between the support and the tile. The support contacts may
be recesses for receiving correspondingly shaped bumps on a tile,
or bumps for receiving correspondingly shaped recesses on a tile.
The support contacts may also be resilient conductive members
overlying contact pads.
[0016] In yet another embodiment, the imaging apparatus may include
a separate insulating substrate, which is located between the
imaging device tile(s) and the imaging support and is aligned to
enable electrical contact between each support contact and a
corresponding tile contact via a respective resilient contact
member. In this embodiment, each resilient conductive member is a
ring having a hole for aligning bumps of the tile contacts or of
the support contacts with corresponding contacts of the support, or
corresponding contacts of the tile, respectively. The resilient
conductive members may be conductive rubber, conductive polymers or
metal springs.
[0017] The mounting arrangement may be adapted to apply an
adjustable mounting force for removable mounting a tile at a tile
mounting location. The mounting arrangement may include a hole for
each tile mounting location, the hole being of appropriate diameter
to accommodate securing member protruding from the tile. A fastener
for engaging with the securing member can be provided for each hole
on the support at each tile mounting location. In a particular
embodiment, the fastener is a nut and the securing member is a
screw, the nut being adapted to be tightened on the screw after the
imaging device tile has been positioned on the tile mounting
location with the screw extending through the hole, whereby the nut
is used to secure the tile at the tile mounting location with an
adjustable mounting force. Alternatively, the mounting arrangement
may include a screw located or locatable at each imaging device
tile location, for engaging with a threaded hole in a mount of an
imaging device tile.
[0018] According to another embodiment, the imaging apparatus may
include a plurality of different imaging supports and a common set
of imaging device tiles which are mountable on a selected imaging
support at any one time, but are removable, whereby they may be
mounted on another one of the imaging supports. An imaging support
for apparatus such as those described above may provide a plurality
of respective tile mounting locations on a support surface, the
mounting locations being tilted to provide sawtooth deviations from
the support surface. The support may include an arrangement for
mounting an imaging device tile at each mounting location in a
non-destructive, removable manner. The support enables the use of a
planar imaging device tile.
[0019] An imaging device tile for imaging apparatus such as those
described above may include an imaging device having an imaging
surface, a non-active region at or adjacent an edge of the tile, a
mount having a mounting surface for mounting the tile on an imaging
support and a structure for supporting the imaging device on the
mount such that the imaging surface is at an angle to the mounting
surface. This form of imaging device tile enables the use of a
support which does not have sawtooth deviations for the tile
mounting locations.
Brief Description of the Drawings
[0020] FIG. 1A is a schematic cross-sectional view of part of an
imaging support according to an embodiment of the present
invention.
[0021] FIG. 1B is a schematic cross-sectional view of the part of
the imaging support of FIG. 1A with one example of an imaging
device having a mount.
[0022] FIG. 1C is a schematic view of the underside and a part
cross-sectional view of the side of the imaging device mount for
the imaging device of FIG. 1B.
[0023] FIG. 1D is a schematic cross-section view of a part of the
imaging support of FIG. 1B with the imaging device of FIG. 1B
mounted thereon.
[0024] FIGS. 2A-2D are views corresponding to those of FIG. 1 for a
second example of an imaging device mount.
[0025] FIG. 3A is a schematic plan view of an arrangement of four
imaging devices mounted on an imaging support according to an
embodiment of the present invention.
[0026] FIG. 3B is a cross-sectional view of the arrangement of FIG.
3A along line B-B.
[0027] FIG. 3C is an end view of the arrangement in FIG. 3A in the
direction of arrow C in FIG. 3A.
Detailed Description
[0028] Before describing a particular embodiment of the invention,
examples of possible approaches to removable mounting of imaging
devices will be described. The removable mounting of imaging
devices forms the subject-matter of the assignee's published UK
patent applications GB-A-2,305,095 and GB-A-2,305,096, which are
hereby incorporated herein by reference.
[0029] According to one particular embodiment of the present
invention, by way of example only, the imaging devices may be
Active Semiconductor Imaging Devices (ASIDs) as described in the
assignee's published International patent application WO 95/33332,
which is hereby incorporated herein by reference. An ASID is an
active, dynamic semiconductor pixel imaging device with dimensions
from, possibly, a few square mm to several square cm.
[0030] A cross-section of one such imaging device tile 24 is shown
schematically in FIG. 1B over a tile mounting location on a circuit
board 9 of an imaging support. FIG. 1A is a schematic cross-section
illustrating the application of an insulating layer 29 and
conductive rubber rings 16 over the circuit board 9. FIG. 1C
provides a view of the underside and a cross-section view of an
imaging device mount (e.g., a printed circuit board or PCB) 5. FIG
1D is a cross-sectional view of an imaging device tile 24 secured
at a tile mounting location by engagement of a nut 33 over a screw
31 of the imaging device tile 24 (shown disengaged in FIG. 1B).
[0031] The surface area of the imaging device 20 can vary depending
on the application and the semiconductor materials chosen. Typical
sizes are of the order of one square millimeter to several square
centimeters, although the present invention is not limited to
imaging devices of any particular size. Radiation enters a
semiconductor detector layer 1 from an imaging surface (the top
face in FIG. 1B) and upon absorption creates an electric charge. On
the exit face of the detector layer 1, electrode pads (not shown)
define detector cells or pixels. Charge created from successive
radiation hits is accumulated on the corresponding pixel circuits
in a readout layer 3 which are connected to the detector pixels via
conductive microbumps 2 (e.g. indium bumps--not shown). The pixel
circuits are formed on a semiconductor readout chip which forms the
readout layer 3. The imaging device 20, formed by the detector
layer 1 and the readout layer 3, is mounted on a mount 4, for
example a printed circuit board. The imaging device tile 24 is
formed by the combination of the imaging device 20 and the mount
4.
[0032] Each imaging device 20 may have tens of thousands of pixels,
but only needs approximately 5-15 external lines that will provide
control signals, supply voltage and will readout the signal. These
lines are provided on the mount 4 and also on a circuit board 9 of
an imaging support on which the imaging device tile 24 is mounted.
The imaging device tile 24 itself carries a number of tile contacts
5 in the form of, for example, small metal spheres or bumps. The
number of contacts typically corresponds to the number of external
lines. The tile contacts 5 match an equal number of
appropriately-sized support contacts 7 on the circuit board 9 of
the imaging support. The contacts on the circuit board 9 of the
imaging support are connected to the aforementioned control, supply
and signal lines (not shown). In the present example, an
intermediate insulating layer 29 is provided between the imaging
device mount 4 and the circuit board 9 of the imaging support.
Holes 30 are provided in the insulating layer 29 at positions
corresponding to the tile contacts 5 and the support contacts 7.
Conductive rubber rings 16 are located in the holes 30 in the
insulating layer 29.
[0033] Good electrical connection between each tile contact 5 on
the imaging device mount 4 and the corresponding support contact 7
on the circuit board 9 may be ensured by separate conductive rubber
rings 16. These are placed in appropriate holes of the insulating
layer 29, which is aligned and glued on top of the circuit board 9.
The use of conductive rubber rings (i.e. with holes) is not
essential, and conductive flexible pads may be used instead.
However, the use of a ring structure with a central hole may be
advantageous for aiding alignment of the imaging device.
Alternatives to the conductive rubber rings 16, such as conductive
polymers or metal springs, may also be used. A screw 31 may be
glued into a hole 34 in the imaging device mount 4. This screw is
pushed through the hole 32 in the circuit board 9 of the imaging
support and is secured by the nut 33. The nut is tightened to press
the tile contacts 5 of the imaging device mount 4 against the
rubber rings 16, which in turn are pressed against the support
contacts 7 of the imaging support circuit board 9, ensuring good
electrical contact.
[0034] The embodiment illustrated in FIGS. 1A-1D is particularly
suitable for providing an imaging area having a plurality of easily
removable semiconductor pixel imaging devices as described in the
assignee's published International patent application WO 95/33332,
or other types of pixel semiconductor imaging devices. If a
particular example, such as mammography, is considered, an imaging
surface of 30 cm by 30 cm (about 600 imaging devices of the type
described in the assignee's published International patent
application WO 95/33332) will be needed. The 600 imaging devices
will be mounted on a printed circuit board 9 of the imaging
support.
[0035] Since individual imaging devices may be removed and
re-positioned any number of times, the same imaging devices can be
used in a number of applications. For example, imaging devices used
for mammography can be quickly transferred on a different imaging
support for chest X-rays. A variety of imaging supports can have
different sizes and shapes but only one set of imaging devices is
needed. Additionally, replacing an imaging device can be done by a
non-expert and maintenance costs are minimized. Accordingly,
contrary to prior approaches where large imaging areas have
monolithic imaging means or a fixed tiled imaging plane,
embodiments of the present invention provide a new large area
imaging system where the imaging mosaic is made of removable
imaging devices allowing for multi-purpose use and re-use of the
individual imaging devices, while also allowing cost effective
maintenance of the imaging areas.
[0036] By means of the screws and nuts it is also possible
individually to adjust the mounting force for each imaging device
to ensure good alignment and good electrical contact using flexible
contact elements such as the conductive rubber rings. Alternatives
to the specific example of the nuts and screws are possible while
still retaining the advantages of this mounting approach. For
example, wing nuts can be used to aid tightening and subsequent
release of nuts. Also, the nuts could be provided with an elongate
form on the screws, and the holes in the support plane could be in
the form of slits, so that the elongate nuts could be inserted
through the slots and then tightened so that the elongate nut
engages with the rear surface of the support plane. By suitably
configuring the dimensions of the nut and the slot, a desirable
range of rotary adjustment may be provided. As a farther
alternative, a rotatably mounted pin may be provided on the rear of
the mount for the imaging device, which pin is provided with at
least two perpendicular projections to be passed through an
equivalently shaped key hold in the support plane, the pin then
being turned after insertion through the keyhole so that the
projections engage behind support plane to secure the imaging
device.
[0037] Another example of an approach to the reversible and
non-destructive mounting of imaging devices using screws is
illustrated in FIGS. 2A-2D. The four schematic views 2A, 2B, 2C and
2D correspond generally to those of FIGS. 1A-1D, except that in
this case the mount 4 of the imaging device is provided with a
threaded hole 35 into which a screw 36, which is rotatably mounted
at an imaging device location on the support plane 9, could be
engaged to secure the imaging device to the support plane. The
screw 36 could be inserted through a hole 32 in the support plane 9
at the imaging device location when it is desired to attach an
imaging device at the location.
[0038] Alternatively, and as shown in FIGS. 2A-2D, the imaging
device could be permanently mounted, in a rotatable manner, at the
imaging device location. For example a neck on the screw could be
mounted in a collar 37, which collar is then attached over the hole
32 in the support plane at an imaging device location so that the
screw 36 is rotatably mounted at that location. In this example,
the imaging device support will have an array of upstanding screws
36 to which the imaging devices with threaded holes can be
attached. This example provides advantages as regards ease of use.
As an alternative to a screw 36 and threaded hole 35 in this
embodiment, other similar arrangements, for example a stud with
bayonet pins rotatably mounted in the support plane 9 and
cooperating hole with bayonet pin receiving structures on the mount
4 could be provided.
[0039] Now that examples of techniques for the non-destructive
mounting of imaging devices has been described, the use of such
techniques in an embodiment of the invention will be described. It
will be noted in FIGS. 1B and 2B, that there are two steps at the
left hand end of the imaging device. The first step 12 is between
the detector layer 1 and the readout layer 3, and the second step
14 is between the readout layer 3 and the mount 4. The purpose of
these steps is to enable the connection of bond wires (not shown)
between contact pads on the readout chip and respective contact
pads on the mount 4. This provides for the external electrical
interface of the readout chip to the tile contacts 5 mentioned
previously. In the readout chip, all internal electrical
connections are brought to a single end of the chip to facilitate
this connection and also to reduce the amount of dead imaging area
for a mosaic of imaging device tiles. It will be appreciated that
when the imaging devices tiles are arranged side-by-side and
end-to-end, dead spaces (i.e., areas over which the detector does
not extend) occur at the stepped region described above. Also, in
conventional tiled arrays, spaces between adjacent imaging devices
arranged side-by-side occur as the supports are wider than the
detector surfaces. Approaches to dealing with this problem have
been proposed which involve staggering adjacent rows of imaging
devices on an imaging array and then providing for relative
movement between an object to be imaged and the imaging array. This
means that the effect of the dead spaces can be at least
substantially eliminated, but this does require the provision of a
mechanism for the relative movement and appropriate software for
processing the resultant multi-exposure image. Embodiments of the
present invention provide a mechanism which can mitigate or
completely eliminate the disadvantages of such prior
approaches.
[0040] Part of another embodiment of the present invention is
illustrated schematically in FIGS. 3A-3C. In this embodiment the
structure of the individual tiles is modified to enable adjacent
tiles to be mounted very close to or even touching each other. The
tiles can be connected both electrically and mechanically to the
support plane in, for example, one of the ways described above,
although other suitable mounting techniques could be employed.
[0041] In the particular embodiment shown in FIGS. 3A-3C,
electrical connection between an imaging device mount (e.g., tile
PCB) 41 and a support plane 42 is achieved by the contact between
conductive (e.g., metal) balls 44 on the imaging device mount 41
and conductive rings 45 (e.g., of rubber), placed in appropriate
holes in an electrically insulating intermediate plane 46, which is
aligned and glued on top of the support plane 42 so that the rings
45 overlie contact pads (e.g., of metal) on the support plane 42.
Mechanical connection is assured by means of a screw 48, which is
glued into a hole in the imaging device mount 41. This screw is
pushed through a hole in the support plane and secured by a nut 47.
The nut 47 is tightened to press the conductive balls 44 of the
imaging device mount 41 against the rings 45 which in turn are
pressed against the metal pads of the support plane ensuring good
electrical contact.
[0042] In this embodiment, the signal detecting element (i.e., the
detector 38 and the readout chip 39) is tilted, or angled, by
applying a support structure 40 of triangular or wedge shape
between the imaging device mount 41 and the readout chip 39. One
edge of the detector 38 and the readout chip 39 can then be
extended to cover the wire bond pads and the bond wires 43 of the
neighbouring imaging tile. The wire bond pads are provided on the
imaging device mount 41 for the attachment of bond wires 43, which
enable the pixel circuits on the readout chip 39 to be electrically
connected to the imaging device mount 41. In this way the dead
space which would otherwise be present between the imaging tiles
when mounted on the support plane 42 is minimized or even
completely eliminated. The elimination of this dead space means
that alternative techniques to provide complete image coverage (for
example, moving the support plane 42 and taking multiple exposures)
are not required.
[0043] In this embodiment a rectangular shape of individual imaging
tiles with one elongated side (preferably as long as possible) is
chosen to minimize any parallax error which may be caused by the
tilting (i.e., minimize the tilting angle). For example, the
dimensions of the detector 38 and the readout chip 39 can be 18 mm
by 10 mm, but many other dimensions are possible depending on the
processing of the readout chip 39 and the detector 38. FIG. 3A
shows a planar view of the tile arrangement (four tiles in this
example, although there will typically be many more tiles in an
array). FIG. 3B is a cross-sectional view at B-B. FIG. 3C is an end
view in the direction of the arrow C.
[0044] In FIG. 3A, the bonding wires 43 and the stepped uppermost
end 50 of the uppermost imaging device tiles 52, 54 (as viewed in
FIG. 3A) can be seen. However, the bonding wires 43 and the stepped
uppermost end 50 of the lowermost imaging device tiles 56, 58 (as
viewed in FIG. 3A) cannot be seen as these are covered by the
lowermost end 60 of the uppermost imaging device tiles 52, 54 when
viewed from above (i.e., looking down on the plane of FIG. 3A).
This is a result of the tilting of the signal detecting elements
comprising the detector 38 and the readout chip 39 as can be seen
in the cross-sectional view of FIG. 3B. In the particular example
shown in FIGS. 3A-3C, where the detector 38 and the readout chip 39
are approximately 18 mm by 10 mm, and the tilt provides a
difference in the "height" (i.e., the horizontal distance D as
viewed in FIG. 3B) of the imaging device over the support board
between the ends of the imaging device of about 1 mm, the angle of
tilt of the imaging device and the imaging surface is about
3.degree..
[0045] The space between tiles in the direction orthogonal to the
tilting direction (which corresponds to the section line B-B) may
be minimized by ensuring that the width of the imaging surface of
the detector 38 (i.e., in the horizontal direction as viewed in
FIG. 3A) is the same as or greater than that of the readout chip 39
and the imaging device mount 41. In this manner, the tiles can be
mounted so that the detectors actually touch or are separated by a
very small amount in that direction.
[0046] With an embodiment of this type, the dead space introduced
by the bonding pads, bonding wires and readout buffers (e.g.,
decoders, multiplexers, etc.) on the readout chip 39 and the dead
space introduced by the imaging device mount 41 is eliminated
because there is overlap of the total dead region with the
detecting element 38 of the adjacent tile. Also, there is minimal
or no dead space at all between tiles in the other direction since
tiles are configured to be substantially proximate to or to touch
each other and the detector elements 38 may indeed be configured to
be precisely equal or extend slightly beyond the dimensions of the
readout chip 39.
[0047] While in FIGS. 3A-3C an arrangement of four tiles is shown
it can be appreciated that any number of tiles can be arranged to
provide an imaging area with any practically useful size, for
example 45 cm by 40 cm. Also, although in the above described
embodiments reference is made to a support plane, this need not in
fact be planar, but could be curved or shaped to fit form a desired
imaging plane. For example the imaging support could be shaped as
part or the whole of a ring for certain applications.
[0048] The contacts on the imaging support may be connected in turn
to control electronics and output electronics (not shown) for the
imaging array. The output electronics may include one or more
analog to digital converters for converting analog signals from the
imaging devices into digital signals for processing and displaying
image data. An example of suitable control and output electronics
and an image processor is described in the assignee's published
International patent application WO 95/33332. This International
patent application also describes examples of semiconductor pixel
imaging devices suitable for use with the present invention. Thus
the signal detecting elements referred to above can, for example,
be an imaging device which provides an array of imaging cells (or
pixels), each including a radiation detector cell and corresponding
charge storage for storing charge directly resulting from radiation
incident on the radiation detector cell, the charge storage of
respective imaging cells being individually addressable for charge
readout and/or resetting. However, it should be noted that imaging
devices other than semiconductor pixel devices may be used, such as
removable CCDs, NaI crystals or small scale wire gas chambers.
[0049] Embodiments of the present invention thus provide a
stationary tiled imaging area with minimum or indeed no dead space
at all. Such embodiments provide tilting of the tiles in the
direction of maximum dead space and allowing for overlap between
the detecting element of one tile and the dead area of an adjacent
tile. In the other orthogonal direction, tiles are arranged as
proximate to each other as possible or even touching each other.
All tiles are individually removable as previously described, thus
offering an ideal digital imaging plane that can be maintained in
parts without compromising performance.
[0050] Although in the embodiment of FIGS. 3A-3C, a wedge-shaped
support structure is shown between a planar detecting element and a
planar PCB mount, it will be appreciated that alternative
constructions may be employed to provide an angled arrangement of
the imaging surface of the detecting element. For example, blocks
along one edge, rather than a wedge-shaped structure, may be used.
Also, the imaging device or the mount may be wedge shaped, or
provided with integral supports at one edge for an angled mounting.
Alternatively, the mounting locations of the imaging support could
be angled (tilted), or wedge-shaped, at each mounting location for
the imaging devices to provide the angled and overlapping mounting
of those devices.
[0051] Using an embodiment of the invention, for example with the
mounting techniques described above, it is possible to configure a
variety of clinical equipment with the imaging supports ready and
mounted on the corresponding systems awaiting the imaging devices.
Imaging devices can be properly packaged and supplied separately
from the rest of the imaging system and any average technical
employee can handle them and relocate them from one plane to
another. In this way, the use of the relatively expensive pixel
semiconductor imaging devices is optimized by requiring less
imaging devices than are needed simultaneously to equip all
systems. In addition, maintenance becomes cost effective. A
defective imaging device can be substituted rather than the whole
imaging surface (mosaic) and this can be done easily by an average
technical employee.
[0052] The removable securing can be achieved in a non-destructive
way such that an imaging devices may be secured to and removed from
an imaging support a plurality of times leaving the imaging device,
the board(s) and corresponding contacts in substantially the same
state. An arrangement for mounting imaging devices in a removable
manner may be implemented using any of a wide variety of
techniques, including:
[0053] reduced air pressure or vacuum, whereby the imaging devices
are effectively "sucked" into position;
[0054] screws glued to the PCBs or other mounting means of the
imaging devices and then pushed through corresponding holes in the
support plane (e.g., the circuit board of the imaging support), the
screws being then secured by nuts on the opposite side of the
support plane;
[0055] a socket configuration (e.g., zero-insertion force socket
means) whereby the imaging devices have pins that plug into
corresponding sockets on the support plane;
[0056] clips, whereby the imaging devices are kept in position with
mechanical clips, strings or the like;
[0057] magnets, whereby small magnets, either on the imaging
support or on the imaging devices, or both, secure the imaging
devices to the imaging plane; and
[0058] other mechanical arrangements.
[0059] Embodiments of the present invention may be used for any
radiation type in any radiation imaging field where areas larger
than a few square mm are needed. In particular, such embodiments
find application in medical diagnosis imaging with X-rays and
gamma-rays, in biotechnology imaging with beta-rays (where isotopes
are used as labels on the samples to be image) and in industrial
applications for non-destructive testing and product quality
control.
[0060] Although illustrative embodiments of the invention have been
described in detail herein with reference to the accompanying
drawings, it is to be understood that the invention is not limited
to those precise embodiments, and that various changes and
modifications can be effected therein by one skilled in the art
without departing from the scope and spirit of the invention as
defined by the appended claims.
[0061] For example, in the embodiment described with reference to
FIGS. 3A-3C, the tiles are tilted with respect to one axis (one
direction) with adjacent rows of tiles being arranged so that the
detector areas substantially touch each other. However, in an
alternative embodiment, it is possible for the tiles to be tilted
with respect to two axes (i.e., about two orthogonal directions,
each parallel a respective side of a square tile or about a single
axis which passes through two opposite comers of a tile) so that
dead regions along two adjacent edges of one tile may be covered by
the detector imaging surface of two adjacent tiles which meet at
the corner between those adjacent edges. In order to visualise this
embodiment, it is helpful to think of the tiles being arranged like
the scales of a fish or in diamond shapes rather than as a
rectangular array of rows and columns of tiles. In other words, for
any one tile, two edges which have dead spaces either side of a
first corner will be lower than the two opposite edges either side
of the opposite corner. Thus the dead spaces of the two lower edges
of the tile in question will be covered by the detector imaging
surface at the higher edges of two respective adjacent tiles. Also,
the opposite, higher edges of detector imaging surfaces of the tile
in question will overlie part of the dead space at the edges of two
further adjacent tiles. For such an alternative embodiment, it is
advantageous for the tiles to be substantially square as opposed to
being elongated rectangles. This embodiment if useful for imaging
devices having bond wire connections or other dead spaces along two
edges, rather than along a single edge as in the preferred
embodiment of FIG. 3.
* * * * *