X-ray system

X-ray or gamma ray systems or devices – Accessory – Object holder or support

Reexamination Certificate

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Details

C378S019000

Reexamination Certificate

active

06672761

ABSTRACT:

This invention relates to an x-ray system, particularly a system for viewing the internal structure of miniature electrical devices.
Miniature electrical devices are known with external electrical bonds whereby an electrical lead is soldered to the device. These kind of bonds are visually inspected, usually with a magnification device because they are too small to be seen by the naked eye. Typically such bonds may be a few microns in diameter.
More recently such devices have included electrical bonds formed at a planar interface of two electrical components. Such bonds are of course hidden from the naked eye by the face to face contact, and it has been proposed to inspect such bonds using an x-ray inspection device.
The aim of the present invention is to provide an x-ray inspection device which has improvements in design, manufacture and use.
A first aspect of the invention relates to a cabinet for an x-ray inspection system. In general terms the cabinet comprises a frame to provide mechanical support for the system components, and an enclosure to provide protection against mechanical, electrical and radiation hazards.
A known cabinet comprises a skeletal frame to which are attached infill panels, and which is designed to support the x-ray system and associated mechanical and electrical equipment. Lead sheet is applied to the frame to contain radiation, followed by external cladding panels.
A significant problem with this kind of construction is that it is very time consuming and expensive to manufacture and assemble the elements of the frame, and the infill and cladding panels to be attached to the frame. It is also problematic to ensure that the lead shielding fits closely to the frame, and is thus fully effective. An additional problem is that it is very difficult to shield that portion of the frame which protrudes to the exterior to provide an attachment for the external cladding panels. Furthermore, a skeletal frame has spaced frame members which may not be adaptable to a different internal configuration of components, without the use of adapter plates, sub-frames or the like.
According to a first aspect of the present invention, a cabinet for an x-ray system comprises an inner housing having an open mouth and being fully insertable with a clearance in an outer housing having an open mouth, the inner and outer housings having attachment means to secure and space the housings in a predetermined relationship, wherein lead shielding comprises a substantially complete intermediate layer extending between the inner and outer housings, and wherein the open mouth is provided with a lead lined closure.
Such a construction provides a relatively light and inherently stiff cabinet by virtue of the spacing of the inner and outer housings. The intermediate lead shielding is preferably applied to substantially the whole exterior of the inner housing before assembly of the outer housing, and is relatively easy to apply because the prior art frame is absent. Special shielding measures need to be taken in the region of attachments of the inner and outer housings, but these are less of a problem than with the prior cabinet construction, in which the skeletal frame protrudes to the exterior; these attachments may in any event be formed after application of the lead shielding in the inner housing. The cabinet according to this aspect of the invention is significantly less expensive to manufacture and assemble than the prior cabinet.
The cabinet of the invention has the particular virtue that the outer housing, which replaces the prior art external cladding, contributes to the strength and rigidity of the cabinet whilst completely enclosing the lead shielding. Furthermore the outer housing comprises an unitary shell for the lead shielding, and can maintain the shielding in place in the event of, for example, a failure of means attaching the shielding to the inner housing. The shielding is preferably restrained by inwardly protruding bosses of the outer housing. The number of fasteners for the cabinet is substantially reduced over the prior construction because separate infill and cladding panels are not required, and the weight of the cabinet is also substantially reduced.
The inner housing comprises a load bearing enclosure capable of supporting components at any location; such a cabinet is accordingly adaptable to many internal configurations of components, and can be re-used in the case of an alternative configuration without adapter plates and the like.
An x-ray inspection device comprises an x-ray source from which an x-ray beam is emitted, and an image intensifier which receives the beam and causes an image to be formed. An object placed between the source and the intensifier may absorb x-rays, and cause a shadow to appear as the image. By moving the object and intensifier relative to the source, the image may be magnified. A video camera provides real time display of the image on a monitor external to the inspection device.
The object may be placed on a manipulator movable in the X, Y and Z axes, and the intensifier is typically placed on the Z axis in line with the x-ray beam. Such an arrangement permits the object to be moved along the Z axis towards and away from the source, and traversed in the X Y plane. Devices for moving a manipulator in the desired three axes are known.
It would be useful to be able to inspect an object other than along the Z axis, and the present invention provides a compact and relatively simple solution to this requirement.
According to a second aspect of the invention, a movable support of an x-ray inspection device comprises a planar frame, a primary carriage mounted on the frame and movable in the plane of the frame from side to side in a first direction, and drive means to move the carriage with respect to the frame, wherein the carriage is pivotable in said plane about an axis perpendicular to said first direction.
Such an arrangement permits an image intensifier to be mounted on the carriage and be tilted towards a relatively fixed x-ray source as the carriage moves sideways in the frame away from nominal position.
Thus, in the nominal position an x-ray source and an image intensifier are aligned on the Z axis with an object therebetween. By moving the intensifier sideways, and tilting it towards the source, the object may be viewed at an angle, so permitting non-perpendicular inspection at e.g. up to 45°. The object may also be moved sideways in order that the image of a particular feature is in the centre of the field of view, and the object may be moved towards or away from the intensifier in order to change magnification.
Preferably the carriage is pivotable on both sides of the nominal position so as to permit inspection at ±45°, In a preferred embodiment the primary carriage is itself mounted on a secondary carriage which permits tilting in a plane at right angles to the tilting plane of the primary carriage. This arrangement permits all round viewing of an object
In an alternative embodiment, the carriage is movable linearly, and is tiltable so as to permit inspection at 0-45°, and a rotary table is provided on the manipulator to support an object. This arrangement also permits all round viewing of an object by rotating the table by up to 360° so that the object is in the line of sight of the image intensifier.
The carriages and manipulator are preferably servo controlled to ensure precise alignment. The rotary table, where provided, is also preferably servo controlled in order to ensure a precise angular displacement from the datum position.
In the preferred embodiment the or each carriage is mounted on upper and lower linear bearings extending across the frame, and is driven in a manner which ensures higher relative velocity in one bearing than the other, preferably by toothed belt drive. This arrangement ensures precise pivoting with respect to the nominal (vertical) position, and ensures that the intensifier axis remains centred.
A single motor may provide toothed belt drive to both the upper and lower bearings, the differential velo

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