Abstract: A mount for a radiotherapy apparatus comprises a cylindrical bearing surface to allow the mount to be supported in a rotatable manner, a housing extending from the bearing surface and having an extent in a direction along an axis of the cylindrical bearing surface, the mount having an axial through-hole which encompasses the axis of the cylinder, the housing having at least one opening communicating with the through-hole and extending in a direction transverse to the axis of the cylinder. This mount can be used as the basis for a number of different radiotherapy systems.

Abstract: A radiation delivery system generally includes either a synchrotron source or a support frame and a plurality of microbeam delivery devices supported on the support frame, both to deliver a beam in a hemispherical arrangement. Each of the microbeam delivery devices or synchrotron irradiation ports is adapted to deliver at least one microbeam of radiation along a microbeam delivery axis, wherein the microbeam delivery axes of the plurality of microbeam delivery devices cross within a common target volume.

Abstract: A unit for acquiring dental radiographic images of a patient is provided with an x-ray head coupled to a respective supporting arm via a ball joint.

Abstract: An X-ray CT apparatus, wherein a drum type rotation frame is rotatably supported by a fixed circular frame so as to surround an outer surface of the drum type rotation frame through a plurality of bearings provided between an inner surface of the fixing circular frame and an outer surface of the drum type rotation frame, for example in ring-like configuration. When the drum type rotation frame receives a large centrifugal acceleration due to a high speed rotation, outside expansion of the drum type rotation frame can be constrained due to both the rigidity of the fixed frame and the rigidity of the plurality of bearings provided on the outer surface of the rotation frame, thereby to maintain the relative positions of the X-ray tube and the X-ray detector and prevent deterioration of reconstructed images.

Abstract: The invention relates to an X-ray device, in which an X-ray source and an X-ray detector are attached, in an opposed arrangement oriented toward a rotational axis, to a common holder capable of rotating about the rotational axis. To simplify the design of the X-ray device, it is proposed that the holder is attached to the hand of a robot displaying six axes of rotation.

Abstract: An x-ray computed tomography apparatus has a rotor on which are mounted at least one x-ray source and one detector. To avoid unwanted deformations of the rotor at high rotation speeds, the rotor is produced at least in segments from a fiber-reinforced composite material with a metal matrix.

Abstract: A robotically controlled five degree-of-freedom x-ray gantry positioning apparatus, which is connected to a mobile cart, ceiling, floor, wall, or patient table, is being disclosed. The positioning system can be attached to a cantilevered o-shaped or c-shaped gantry. The positioning system can precisely translate the attached gantry in the three orthogonal axes X-Y-Z and orient the gantry about the X-axis and Y-axis while keeping the center of the gantry fixed, (see FIG. 1). The positioning apparatus provides both iso-centric and non iso-centric “Tilt” and “Wag” rotations of the gantry around the X-axis and Y-axis respectively. The iso-centric “Wag” rotation is a multi-axis combination of two translations and one rotation. Additionally, a field of view larger than that provided by the detector is provided in pure AP (anterior/posterior) and lateral detector positions through additional combinations of multi-axis coordinated motion.

Abstract: A rotary mechanism uses a rolling element, an outer-ring housing member and an inner-ring housing member. The outer-ring housing member or the inner-ring housing member is divided thicknesswise into two parts, to have a gap at between the two-divided parts of the housing member. Due to this, slide resistance can be caused by deforming the rolling element received in the outer-ring and inner-ring housing members.

Abstract: The invention relates to a mounting device for mounting a beam manipulating device of an X-ray apparatus to a radiation source of the X-ray apparatus, said mounting device comprising a first mounting flange (10) associated with the radiation source, a second mounting flange (20) associated with the beam manipulating device, and fastening means (60) for fixing the first mounting flange (10) and the second mounting flange (20) to each other. It is an object of the invention to facilitate the alignment of the X-ray beam manipulating device with respect to an X-ray beam path or an X-ray beam focus of the radiation source. To achieve this, the alignment means (30) are adapted to be fastened to the first mounting flange (10), the first mounting flange having a first reference surface (31) which is in a predetermined spaced relationship with respect to the X-ray beam path. The first reference surface (31) corresponds with a second reference surface (34) of the second mounting flange (20).

Abstract: The disclosure relates to a localizing unit for an X-ray diagnostic system covered with a sterile drape. In one embodiment, the localizing unit can be sterilized and has an adapter, which includes a means for puncturing the sterile drape and a means for temporarily securing the sterile drape on a housing of the X-ray diagnostic system. The adapter may be detachably held in predetermined holders on the housing of the X-ray diagnostic system and may be positioned on the housing in a reproducible manner. In some embodiments, the means for temporarily securing the sterile drape on the housing includes an elastically deformable, surrounding seal, which upon positioning the adapter, produces a force on the sterile drape in a direction perpendicular to the surface of the housing.

Abstract: The invention relates to a ceiling support for a medico-technical radiation source. The inventive support comprises a telescopic element (2) consisting of several tubes (3) which fit in each other and are connected to a compensation weight device of the radiation source connected to the free end (E) of said telescopic element (2) with the aid of a first cable (12). The inventive weight compensation device comprises a cable drum (11) for winding and unwinding said first cable (12), a helical winch (15) associated thereto and connected to a sliding element (8) by means a second cable, said sliding element being displaceable against a pressure spring (6). The radius of said helical winch (15) gradually reduces according to the increasing force of the pressure spring (6) in such a way that the compensation couple of the weight remains identical aside from the respective length of the telescopic element (2).

Abstract: A system and method for X-ray diagnosis of an examination object is provided. The system includes a component that is movable relative to a stretcher for the examination object and at least one predeterminable set stop position for the component. A position ascertaining device is operative to ascertain a position of the component. A braking device is operative to brake the movable component. A control unit is connected to the position-ascertaining device and to the braking device. The braking device is activatable as a function of the position of the component relative to the stop position.

Abstract: An x-ray tube includes a stationary base and a passage therein. The x-ray tube includes an anode frame having an anode positioned adjacent to a first end and having a neck at a second end, the neck extends into the passage, wherein the anode frame is configured to rotate about a longitudinal axis of the passage. A hermetic seal is positioned about the neck between the neck and the stationary base.

Abstract: A C-arm system is disclosed herein. The C-arm system includes a support assembly, and a C-extension connected to the support assembly. The C-extension is selectively rotatable relative to the support assembly in both a clockwise and a counterclockwise direction. The C-arm system also includes a C-gantry connected to the C-extension. The C-gantry is adapted to retain an x-ray source and an x-ray detector. The C-gantry is selectively rotatable relative to the C-extension in both a clockwise and a counterclockwise direction. The C-extension is operable to extend the range of C-gantry rotation in both clockwise and counter clockwise directions. A corresponding method for operating a C-arm system is also provided.

Abstract: With a view to providing an X-ray irradiator capable of detecting a relative rotational angle of a collimator box with respect to an X-ray tube, the X-ray irradiator comprises: an X-ray tube having a flange formed around an X-ray output window; a collimator box having an entry plate formed with an X-ray incidence window, the collimator box accommodating a collimator in the interior thereof; a ring provided on the entry plate so as to surround the X-ray incidence window, the ring receiving therein the flange of the X-ray tube and having a plurality of slots formed radially through the ring; a plurality of tongue pieces being inserted through the slots from outside to inside of the ring and holding down a back side of the flange; and sensor device provided inside the flange to detect a relative rotational angle of the collimator box with respect to the flange.

Abstract: A support cradle for a computer tomorgraph, in which the rotating body together with the X-ray emitter and the X-ray detector, which is situated opposite said emitter, can be ratably mounted. The support cradle includes a suitable pedestal that has two vertical supports, in addition to a gantry, which is mounted between the vertical supports and can be rotated about a horizontal transverse axis. According to the invention, the support cradle comprises a cooling device that is simple to manufacture. Said device is configured at least partially as a hollow section. A cavity in the support cradle acts as a conduit for supplying or evacuating a coolant.

Abstract: Alpha and X radiation source, PIXE-XRF analysis device using this source, and method for making the source. The source according to the invention comprises a support (2), consisting of a chemical element for which the atomic number is less than 10 or of a plurality of chemical elements each having an atomic number less than 10, which support is covered with a layer (4) of noble metal, having a thickness less than 0.2 ?m, and on which a layer of a material selected from actinides is deposited. According to the method, the layer of the material is formed by electrochemical deposition, from an organic electrolyte based on dimethyl formamide and containing ions of the material.

Abstract: A volume change absorber simple in construction and wide in application range, an X-ray generator having such a volume change absorber, and an X-ray imaging apparatus having such an X-ray generator, are to be provided. The volume change absorber includes a rigid pipe-like member capable of being mounted in an airtight manner through a wall of a vessel into which liquid is sealed and a flexible tube having one end portion mounted so as to cover in an airtight manner an end portion of the portion of the pipe-like member which portion lies inside the vessel and also having an opposite end portion which is sealed in a crushed state.

Abstract: A radical imaging system for use in radical medicine using a movable pallet for moving the patient during radical imaging. With the movable pallet, the patient can be moved, such as rotated to a position such that signal attenuation and scattering can be decreased. The imaging system may also incorporate a collimator with finite focal length, or a collimator whose focal length and/or spatial resolution can be adjusted dynamically.

Abstract: A radiation scanning system comprises a radiation source and a radiation detector that are proximate a crane system that moves objects between the source and the detector for scanning. The source and/or detector may be supported by the crane system or may be near to the crane system. Preferably, the source and detector are supported by the crane system or they are within a profile defined by the crane system. The radiation scanning system is particularly suited to scan cargo conveyances, such as sea cargo conveyances, as they are being removed from or loaded onto a ship. Methods of examining objects are disclosed, as well.

Abstract: In a method for operating an x-ray device, an x-ray beam is generated at a focal spot of a rotary anode that is rotatable around a rotation axis, and the x-ray beam is gated with a slit-shaped diaphragm to produce a fan-shaped x-ray beam, that is moved through an examination region in the manner of a scan. To improve the image resolution, the fan-shaped x-ray beam can be moved over the examination region essentially in the direction of the rotational axis of the rotary anode by tilting the x-ray tube on the focal spot, with the x-ray tube being tilted on the focal spot so that the fan-shaped x-ray beam is always gated from the region of the overall emitted x-ray beam having the highest image resolution or the highest image definition in the movement through the examination region.

Abstract: A radiation therapy/surgery device optimised to meet the needs of the Neurosurgeon is provided, i.e. one for the treatment of tumours in the brain. It combines the qualities of a good penumbra and accuracy, simple prescription and operation, together with high reliability and minimal technical support. The device comprises a rotateable support, on which is provided a mount extending from the support out of the plane of the circle, and a radiation source attached to the mount via a pivot, the pivot having an axis which passes through the axis of rotation of the support, the radiation source being aligned so as to produce a beam which passes through the co-incidence of the rotation axis and the pivot. It will generally be easier to engineer the apparatus if the rotateable support is planar, and more convenient if the rotateable support is disposed in an upright position. The rotation of the rotateable support will be eased if this part of the apparatus is circular.

Abstract: A mounting assembly for supporting an evacuated enclosure within an outer housing of an x-ray tube is disclosed. The mounting assembly comprises a clamp portion having a C-shaped configuration, and a bracket portion having a circular recess that receives at least a portion of the clamp portion therein. The clamp portion includes an aperture that frictionally attaches to a window assembly of the evacuated enclosure. The clamp portion is in turn mechanically attached to the bracket portion such that an aperture in the bracket portion is aligned both with the clamp portion aperture and a window disposed in the window assembly. The bracket portion further includes a concave surface that is shaped to mechanically mate with an exterior portion of the outer housing, thereby securably supporting the evacuated enclosure within the outer housing. The mounting assembly further includes structures for securing the x-ray tube within an x-ray generating device.

Abstract: An x-ray device includes an x-ray tube for generation of an x-ray emanating from a focal spot of a rotary anode rotatable around a rotation axis and a slit-shaped diaphragm for generation of a fan-shaped x-ray beam that is gated from the x-ray and emission is moved through an examination region in the manner of a scan. To improve the image resolution, the fan-shaped x-ray beam can be moved over the examination region essentially in the direction of the rotational axis of the rotary anode by tilting the x-ray tube on the focal spot, with the x-ray tube being tilted on the focal spot so that the fan-shaped x-ray beam is always gated from the region of the overall emitted x-ray beam having the highest image resolution or the highest image definition in the movement through the examination region.

Abstract: An imaging assembly is provided comprising an x-ray tube housing having a tube mounting hub and formed from a lightweight material. A rotating gantry assembly includes a gantry mounting surface adapted to engage said tube mounting hub. A plurality of barrel nut fasteners secure the tube mounting hub to the gantry mounting surface while reducing stress in said x-ray tube housing.

Abstract: A technique is disclosed for presenting a sample to a radiation interface of an analysis engine employing x-ray, neutron ray, gamma ray or particle-beam radiation to analyze the sample. A protective barrier, transparent to the radiation, and separating the sample from the engine, is moveable relative to the radiation interface, using a barrier movement system. The barrier in one embodiment is a film movable over a cavity in which the sample placed, and moveable with a system of reels to provide and retrieve a generally continuous supply of film over the cavity. The cavity may form a portion of a sample path through which the sample is moveable. If the sample path is pressurized, the film maintains the pressure during analysis of the sample by the analysis engine.

Abstract: An x-ray source provides both a line focus output and a point focus output, and is mounted on a rotatable support to allow easy changing between the two. A housing has ports at different angular positions relative to an anode, and each port has an associated optic appropriate for an x-ray beam passing through that port. Three or four ports may also be used to allow for different types of beam conditioning. The different beam optics may also do conditioning based on wavelength, and the anode may be of a composite material to provide different wavelength ranges. The rotatable support may be manual or motorized, and a lockout mechanism may be used to ensure that only one port is active at a time. The support may also be located on a movable table that is movable in multiple perpendicular directions.

Abstract: An X-ray diagnostic apparatus includes two photographic systems, a control circuit controlling a movement of the second photographic system. A control circuit which controls movement of a photography system can move the photographic system to a temporary evacuation position closer to a photography position than an evacuation position, according to an instruction from an operator.

Abstract: An x-ray source assembly (2700) and method of operation are provided having enhanced output stability. The assembly includes an anode (2125) having a source spot upon which electrons (2120) impinge and a control system (2715/2720) for controlling position of the anode source spot relative to an output structure. The control system can maintain the anode source spot location relative to the output structure (2710) notwithstanding a change in one or more operating conditions of the x-ray source assembly. One aspect of the disclosed invention is most amenable to the analysis of sulfur in petroleum-based fuels.

Abstract: A novel image capture device, system and method are disclosed for use in capturing dental images. A novel collimator tube includes one or more devices integrated within its wall, such as a radio frequency transmitter, a camera, a frame grabber, or a transilluminator light. The integrated devices are used instead of or in addition to an x-ray generator, which is coupled to the collimator tube. The camera is used to capture digital images. The camera is either a camera port for plugging in an external camera, such as an intra-oral camera, or is wholly contained within the collimator tube. The radio frequency transmitter transmits digital data to a remote computer. The frame grabber captures digital data for display on a display device. The transilluminator light can illuminate an area for digital capture. A novel receptor holder includes a docking port for docking a sensor that is used for digital x-ray capture.

Abstract: There is described an X-ray system having at least one component (12, 2, 31, 32) that is shiftable (moveable) or pivotable along at least one traverse path to at least one predeterminable locking position (Bx). Components of this kind are in particular the moving parts of a stand such as the moving parts of a ceiling stand (1), floor stand or wall stand for an X-ray generator (2, 21), and the X-ray generator (2, 21) that is fastened to the stand in such a way as to be capable of being pivoted and extended or retracted. Such components also include the shiftable (moveable) or pivotable top of a patient table and a film cassette that is displaceably or pivotably mounted in the table or on a wall stand.

Abstract: A motor-adjustable X-ray system comprises a C-arm, which has two degrees of freedom and is adjustable with a motor support. The motor support has a force pickup device which is provided to detect a force exerted by an operator when manipulating the C-arm. The force pickup device is configured to detect a plurality of directional components of the exerted force and to cooperate with an evaluation unit, by which as a function of the plurality of the directional components of the exerted force, different amounts of motor support of the C-arm in the two degrees of freedom are established via the evaluation unit.

Abstract: A sterilizing drape which can be used to cover a C-arm machine in combination with a small surgical table. The invention assumes that a small surgical table has been affixed to the lower portion of a C-arm machine. The sterilizing drape covers the exposed portions of the C-arm machine as well as the small surgical table. An integrated version is disclosed which covers the C-arm machine, the small surgical table, and the patient. Other embodiments are disclosed which cover these areas using separate pieces.

Abstract: An x-ray emitting window is formed at a front end face, and a taper surface tilted with respect to the x-ray emitting direction is formed near the emitting window, whereby an object to be inspected can be prevented from abutting against the front end face even if the object is pivoted about an axis intersecting the emitting direction while the object is disposed closer to the x-ray emitting window. As a consequence, while the object is disposed closer to the x-ray emitting position, the orientation of the object can be changed. Therefore, when inspecting the internal structure of the object and the like by irradiating the object with x-rays and detecting the x-rays transmitted through the object, not only a magnified penetration image of the object with a high magnification rate is obtained, but also the internal structure of the object and the like can be verified in detail by changing the orientation of the object.

Abstract: With a view to providing an X-ray irradiator superior in workability in mounting a collimator box to an X-ray tube, the X-ray irradiator includes: a ring provided on an entry plate of the collimator box so as to surround an X-ray incidence window, the ring receiving therein a flange of the X-ray tube and having plural slots formed radially through the ring; plural tongue pieces inserted through the slots from outside to inside of the ring and holding down the back side of the flange; and a pair of half-rings which holds the plural tongue pieces at positions outside the ring and which, when one ends and opposite ends thereof are respectively opposed to each other, surrounds the ring with the plural tongue pieces inserted respectively into the plural slots.

Abstract: A container to secure an x-ray source is provided. The container includes a base and a cover each having an inside surface. The base and cover are assembled together forming a fluid tight chamber defined by the inside surfaces of the base and cover to secure x-ray source components to positions along the inside surface of the base. A plurality of these positions are machinable to provide a precision arrangement of at least a portion of the x-ray source components and at least one fluid tight seal between x-ray source components and the base. During fabrication of the base, each position of the inside surface required to provide a precise arrangement of at least a portion of the x-ray source components and at least one fluid tight seal between the x-ray source components and the base being accessible from exterior of the base by a substantially straight tool.

Abstract: The gantry of a tomography apparatus has a drum that is rotatable around an axis. The drum carries at least one component mounted thereon. The component is mounted on the drum by a mounting arrangement that resolves a centrifugal force acting on the component into a radial force vector and a substantially axially proceeding force vector. The mounting of the component is thereby made less susceptible to breakage due to the high centrifugal forces that occur upon rotation of the gantry.

Abstract: An X-ray apparatus has hollow motors providing hinge joints for a mobile part in rotation relative to a reference part. Each of the motors includes a rotor fixed to the mobile part as well as a stator fixed to the reference part. The axis of these motors is indistinguishable from the axis around which the mobile part can go into rotation. The motors facilitate an assembling of the parts of the apparatus in permitting cables or wires to cross through the hollow motors. The hinge joints provide a direct transmission between the mobile and reference parts.

Abstract: An x-ray generating assembly is provided comprising an x-ray source assembly mounted to a mounting element. The assembly further includes a support assembly comprising a motor element and a gear assembly in communication with the motor element. An output shaft is in communication with the gear assembly such that the output shaft rotates in response to the motor element. The mounting element is positioned around the output shaft. An electromechanical lock is engaged to the mounting element such that the electromechanical lock rotates in concert with the mounting element. The electromechanical lock has an engaged condition and a disengaged condition. The electromechanical lock engages the mounting element when the electromechanical lock is in the engaged condition such that the mounting element rotates with the output shaft. The mounting element is free to rotate when the electromechanical lock is in the disengaged condition.

Abstract: The invention concerns a C-arm x-ray device with a non-isocentric C-arm on which an x-ray source is positioned and that can be orbitally or angularly rotated, whereby the C-arm x-ray device comprises a device fashioned to horizontally adjust the C-arm (which enables an adjustment of the C-arm within the plane of the C-arm) and a device fashioned to vertically adjust the C-arm, where the horizontal adjustment device and the vertical adjustment device are fashioned such that they can automatically move the central x-ray beam of the x-ray source back into the isocenter, given an orbital or angulatory rotation of the C-arm via the horizontal and vertical adjustment device. An appertaining method is also provided.

Abstract: An above table transillumination device has an X ray radiator that can be rotated around the horizontal axis of the radiator stand and that has a swivel lock having a manually actuatable unlocking lever. The unlocking lever is arranged at the front side of the radiator carrier facing away from the radiator stand and is connected to the lever of the swivel lock via a transmission device.

Abstract: A dental x-ray apparatus (10) includes a tube head (11) formed from a cast zinc material. Structural components of tube head (11) include such component (20) formed from a plastic material impregnated with a high molecular weight substance, such as barium sulfite. X-ray apparatus 10 has a control panel (15) in close proximity to the tube head (11), and is preferably DC powered.

Abstract: A modular X-ray diagnostic appliance has as a first module, a base support, as second module, at least one support for the base support, as a third module, at least one component of an X-ray imaging device, as a fourth module, a support device for an object to be examined, and, as a fifth module, a longitudinal carriage which is arranged above the base support and on which the component is mounted. The base support has support-device coupling elements for coupling the support device thereto, support-coupling elements for coupling the support thereto and component-coupling elements for coupling the component thereto. The component-coupling elements have a fixed and/or floating bearing arranged on the base support and connected to the longitudinal carriage. In a method for producing different series of X-ray diagnostic appliances, in which a structurally identical modular base support and a structurally identical modular support device are used for all series.

Abstract: The invention relates to an X-ray device which includes an X-ray source and an X-ray detector which are mounted at a respective end of a common holding device. The holding device being attached to the room by way of a supporting device. In order to realize a more flexible construction of such X-ray devices that are widely used and are usually provided with a holding device in the form of a C-arm and nevertheless maintain a high positioning accuracy. The invention further relates to a supporting device constructed with a plurality of hinged, serially interconnected supporting members. The supporting device is formed notably by a serial manipulator, for example, a conventional robot arm.

Abstract: A radiographic device includes a platform defining a lateral and longitudinal directions and a mounting assembly having a first end pivotably coupled to the platform and a second end, wherein the second end is movable in the lateral and longitudinal directions. A yoke has a first bracket with a cross support coupled to the mounting assembly second end for pivoting about a Y axis extending parallel to the longitudinal direction, and spaced first and second arms are coupled to the cross support. A radiographic head is pivotably coupled to the first and second arms of the first bracket at points along an X axis extending parallel to the lateral direction, wherein the radiographic head is pivotable about the X axis.

Abstract: An object of the present invention is to provide an X-ray generator capable of compensating for the volume expansion of an insulating oil without the necessity of labor-intensive maintenance. A tubular body is included to penetrate through a tank that is sealed while accommodating a high-voltage assembly and an X-ray tube assembly and having an insulating oil poured thereinto. The lumen of the tubular body opens onto the ambient space at both ends of the tubular body. The tubular body expands or contracts depending on a difference between the pressure in the lumen and the internal pressure of the tank.

Abstract: A non-invasive method and apparatus are described for inspecting a cargo container. The method includes the steps of disposing an X-ray source and an X-ray detector on opposing ends of a rotatable boom, rotating the boom in a horizontal plane so that the X-ray source and X-ray detector straddle the cargo container and providing translational relative movement between the boom and cargo container while the X-ray source irradiates the container and the X-ray detector detects and measures X-ray energy passing through the container from the X-ray source.

Abstract: It is an object to provide an X-ray generating apparatus which permits easy alignment of an X-ray tube and easy insulation against high voltages. A screw through hole and pin through holes corresponding respectively to a screw hole and plural pin holes formed in an end face of a base portion of an X-ray tube are formed in an abutment face of a bracket against which the end face of the base portion of the X-ray tube comes into abutment, and a screw and plural pins are inserted respectively from the bracket side into the screw hole and plural pin holes in the X-ray tube through the screw through hole and the pin through holes, thereby mounting the X-ray tube to the bracket. The bracket is formed by an integral structure of FR 4.

Abstract: A description is given of a method and a device for the calibration of an image pick-up device which is sensitive to gravity. Also described are a method and a device for imaging by means of such an image pick-up device; they are used in particular in X-ray systems, for example, systems provided with a C-arm. Calibration is performed essentially by forming and storing a look-up table whereby the calibration data required for the correction of distortions due to the supporting construction is associated with a plurality of position data of the supporting construction. During imaging the direction of the force of gravity relative to the supporting construction is measured; therefrom the position data is calculated and the calibration data associated with this data in the table is read out and used for the correction of the acquired image.

Abstract: A variable friction disc brake for use with a C-arm x-ray imaging apparatus interposed between the support arm and yoke of the imaging apparatus. The variable friction disc is generally comprised of ring having a gap, width both sides of said gap having apertures therethrough such that a bolt may be inserted into said apertures and used to adjust the width of the gap, and the tension on the ring.