Position indicating device for dental x-ray machines

Claim 1

In a position indicating device for x-ray machines, wherein said device includes a tubular member that is rectilinear axially of same, with said member defining a bore of rectangular transverse cross-sectional configuration that extends the length of same and having its internal surfacing lined for x-ray absorption and defining an x-ray receiving end and an x-ray emitting end, and an adapter member for securing said tubular member to an x-ray machine and secured to said x-ray receiving end of said tubular member, the improvement wherein: said tubular member at said x-ray receiving end of same is formed to define a round hub portion having a peripheral rib integral therewith and thereabout defining annular bearing surfaces on either side of same that lie in parallel planes extending normally of said tubular member, with one of said bearing surfaces facing in the direction of said tubular member x-ray emitting end and the other of said bearing surfaces facing in the direction of said tubular member x-ray receiving end, said member hub portion being formed with a circular counterbore that faces oppositely of said x-ray emitting end of said member and lies at said x-ray receiving end thereof, said counterbore defining a side wall that is in circumambient relation about said tubular member bore, collimating material received in said counterbore and extending from said counterbore side wall across said tubular member bore and being formed to define an x-ray collimating opening centered within said tubular member bore and being of a shape complementing that of said tubular member emitting end, said member hub portion being formed to define between said counterbore and said other bearing surface an annular face that forms the terminal end surface of said tubular member at said x-ray receiving end of same, with an annular retaining disc being received in said counterbore about the portion of said collimating material adjacent said counterbore side wall, means for fixing said retaining disc to said tubular member to secure said collimating material to said tubular member within said counterbore, said disc extending short of said tubular member end surface axially of said tubular member and being separated from said adapter member, said adapter member further comprising: a hub portion including means for securing same to the x-ray machine in the mounted position of said device, said adapter member hub portion defining a radial flange having a bearing surface and an axially extending rim wall defining a socket in which said tubular member hub portion is received with said peripheral rib being encompassed by said adapter member rim wall and said adapter member flange bearing surface opposing said rib other bearing surface, a securing collar received over said adapter member rim wall and defining a radial flange directed radially inwardly of said collar and having a bearing surface that opposes said rib one bearing surface, a first antifriction ring interposed between said one bearing surface of said rib and said collar flange bearing surface in face to face engagement therewith, a second antifriction ring interposed between said rib other bearing surface and said adapter member flange bearing surface in face to face engagement therewith, said collar and said adapter member rim wall having threaded engagement for clamping said rings against said tubular member rib under predetermined compression to journal said tubular member in said adapter member, and means for keying said collar and adapter member rim wall together for maintaining said predetermined compression of said rings, said first antifriction ring being proportioned axially of said tubular member to space said collar flange from said adapter member rim wall when said first ring is clamped between said rib one bearing surface and said collar flange bearing surface, said second antifriction ring being proportioned axially of said tubular member to space said adapter member flange from said tubular member end surface when said second ring is clamped between said rib other bearing surface and said adapter member flange bearing surface, said rib defining a peripheral surface that is spaced from said adapter member rim wall radially inwardly of said adapter member rim wall, said collar flange defining a bore having an internal diameter proportioned to space said collar flange from said tubular member, whereby, on rotation of said tubular member relative to said adapter member for adjustment of said tubular member relative to said adapter member, said collimating opening remains stationary axially of said adapter member for 360 degrees of such rotation, and said collar and said adapter member are free of engagement with said tubular member whereBy said rotational movement of said tubular member relative to said adapter member is opposed by frictional forces only at said bearing surfaces.