Radiant energy – Invisible radiant energy responsive electric signalling – Semiconductor system
Reexamination Certificate
1998-07-20
2001-08-28
Epps, Georgia (Department: 2873)
Radiant energy
Invisible radiant energy responsive electric signalling
Semiconductor system
C250S370080
Reexamination Certificate
active
06281506
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an X-ray imaging apparatus incorporating a camera from which electric image signals are picked up, more specifically to an improvement of a camera section having a function of rotating an image.
BACKGROUND ART
An X-ray imaging apparatus is useful in examining VISCUS of a human body or the interior of an object. X-rays radiated to a human body or an object are detected as an X-ray transmission concentration distribution, i.e., an X-ray image, and this X-ray image is converted into a visible-light image. The visible-light image is further converted into electric image signals, and the X-ray transmission concentration distribution or the X-ray image is displayed on a monitor or the like in real time. Image information is stored in a storage of a computer or the like, for later use.
An X-ray imaging apparatus is provided with: an X-ray generator for generating X-rays; an X-ray image intensifier for intensifying and converting an X-ray image, i.e., the X-rays which are output from the X-ray generator and have passed through an object, into a visible-light image; and a monitor device for displaying an output image which is a visible image obtained by conversion by the X-ray image intensifier. The monitor device can display the output image in real time, since it uses a camera that images the output image of the X-ray image intensifier and outputs electric image signals.
X-rays radiated from the X-ray generator pass through an object and are incident on the X-ray image intensifier in the form of an X-ray image. This X-ray image is first intensified by the X-ray image intensifier and is then converted into a visible-light image. This visible-light image is displayed on the output surface of the X-ray image intensifier as an output image.
The output image on the output surface of the X-ray image intensifier is projected through a lens on the imaging surface of the imaging device of the camera. The image projected on the imaging surface of the imaging device is converted into electric image signals by the imaging device, and is displayed on the monitor device.
In the X-ray imaging apparatus, the imaging device, including the X-ray image intensifier and the camera which are arranged to oppose the X-ray generator, with the object located therebetween, is revolved around the object in an arbitrary direction and moved to an arbitrary position.
In this type of X-ray imaging apparatus, the camera has to be revolved around the object in the opposite direction so that the observer can rotate the image in an arbitrary direction, for the correction of the image direction.
In the above X-ray imaging apparatus, the camera can be revolved, for example, in the following method. A board, on which the camera is mounted along with a circuit for driving the camera and a signal circuit for processing video signals output from the camera, is fixed to a disk-shaped flange. Then, this flange is fixed to a lens support frame secured to the X-ray image intensifier by means of a bearing. In this manner, the camera is allowed to revolve relative to the X-ray image intensifier.
However, this method is disadvantageous in that the signal lines and power supply lines led from the board may be easily twisted when the camera incorporating the imaging device is revolved. In this case, the angle of revolution of the camera must be restricted so as to prevent the signal lines and power supply lines from being twisted. During the observation of the object, therefore, the camera may have to be revolved in the opposite direction so as to move the camera to the intended revolving position, which lengthens the time needed for observation.
FIG. 15
is a schematic illustration showing an example of a presently-available X-ray imaging apparatus capable of rotating an image.
As shown in
FIG. 15
, the X-ray imaging apparatus
101
comprises: an X-ray image intensifier
111
for intensifying and converting an X-ray image, i.e., X-rays output from the X-ray generator and passing through an object to be imaged, into a visible-light image; and a camera
121
, i.e., an imaging device, for imaging the output image produced on the output surface and converting the output image into image signals, thereby enabling a video image to be displayed on a monitor device (not shown).
A support frame
123
a
is secured on the output side of a housing
115
in which the X-ray image intensifier
111
is arranged.
The camera
121
is made up of: a lens
123
supported by means of the support frame
123
a
and spaced from the output image
114
of the X-ray image intensifier
111
by a predetermined distance; a CCD imaging device
127
having a disk shape and positioned at the image focus position on a rotatable circuit board
125
; a motor
129
for rotating the circuit board
125
; and a signal transmission mechanism
131
for transmitting output signals of the imaging device
127
, which are sent thereto from the circuit board
125
, to an external circuit, and for applying driving power to the imaging device
127
. By the circuit board
125
, the imaging device
127
is allowed to revolve around the central axis A of a visible-light image transmitted through the lens
123
. The circuit board
125
is rotatably held by support frame
125
a
fixed to the support frame
123
a.
The signal transmission mechanism
131
includes: a gear
133
for revolving the imaging device
127
and circuit board
125
in such a manner that the center of the visible-light image output from the lens
123
coincides with the axis of revolution; an electrode drum
137
which is coaxial with the support frame
125
a
, is supported by a bearing
135
to be rotatable with reference to an auxiliary frame
125
b
inserted into the support frame
125
a
, and permits the output signal from the imaging device
127
to be led to an external circuit; and a plurality of brushes
139
which are fixed to the auxiliary frame
125
b
of the cylindrical support frame
125
a
and electrically connect ring electrodes
136
of the electrode drum
137
to the signal lines and power supply lines. The electrode drum
137
is coaxial with the center of rotation on which the circuit board
125
and gear
133
are rotated, i.e., with the central axis A of the visible-light image output from the lens
123
.
In the X-ray imaging apparatus
101
shown in
FIG. 15
, the output signals of the imaging device
127
, which are output by way of the circuit board
125
, are sent to an external device (not shown) by means of the electrode drum
137
and brushes
139
of the signal transmission mechanism
131
.
With this structure, the signal lines and power supply lines attached to the circuit board
125
do not impose any limit on the angle of revolution of the imaging device
127
.
In the apparatus shown in
FIG. 15
, however, the electrode drum
137
is used. Due to the use of this drum, the camera
121
is inevitably long in the direction of the axis around which the camera
121
is revolved.
In addition, the image formed by the camera
121
must be displayed in the center of the display screen without reference to the position of revolution of the camera
121
. Since the center of the image which the lens
123
forms based on the output image
114
of the X-ray image intensifier
111
must coincide with the center of the imaging surface of the imaging device
127
, the axis of revolution defined by the revolution of the imaging device
127
and the center of the imaging surface of the imaging device
127
must coincide with each other. Further, in order to prevent the resolution from becoming low in the peripheral portions of the image, the plane in which the lens
123
forms an image by the output image
114
must be exactly the same as the imaging surface of the imaging device
127
. It is therefore required that the central axis of the lens
123
and the axis defined by the revolution of the imaging device
127
coincide with each other. When the electrode drum
137
is coupled to the bearing
135
and when the bearing
135
is coupled to the auxil
Fujita Terutoshi
Itoh Katsutoshi
Epps Georgia
Hanig Richard
Kabushiki Kaisha Toshiba
Pillsbury & Winthrop LLP
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