Panoramic tomography X-ray apparatus particularly for dental photography

Claim 1

A panoramic tomography X-ray apparatus particularly for dental photography, which apparatus comprises a fixed frame (30), to which another frame (rotary frame) (11), having an X-ray tube (10) at one end and a film cartridge device (20) for X-ray film (RF) at the other end, is suspended with bearings (12a, 12b, 53a, 53b), and between which X-ray tube (10) and film cartridge (20) the patient's (P) object to be photographed can be positioned, and which apparatus has a drive mechanism by means of which said suspended rotary frame (11) is rotated in a plane, preferably in the horizontal plane, for taking a panoramic X-ray photograph, characterized in that said drive device comprises a drive and guide groove (31) or a corresponding rail system, which is symmetrical with respect to the center plane (C-C) of the apparatus, and which has essentially straight side sections (31S) and a curved section (31R) which connects the side sections together, that a drive unit (33) is installed to interact with said drive and guide groove (31) or similar, which drive unit comprises a drive wheel (40) which, rotated by the drive unit (33), turns said rotary frame (11), that said rotary frame (11) is suspended to said fixed frame (30) by means of a crank mechanism (13, 50, 51) which is, at the X-ray-tube (10) end, jointed to the rotary frame (11) by means of a bearing (12a, 12b), and at the opposite end, jointed to the fixed frame (30) by means of another bearing (53a, 53b) so that, when the rotary frame (11) is in the middle position (figure 4), the two opposite jointing axes (journal pins) (O 1 , 0 2 ) of the crank (50) are positioned in the vertical center plane (C-C) of the apparatus, and that said drive and guide mechanism (33-41) and said crank mechanism are arranged to interact in such a way that, in the front area of the dental arch or similar, i.e. when the corresponding section (31R) of the guide and drive groove (31) is in operation, the rotary frame (11) turns around the front journal pin (51), i.e. the journal pin located on the side of the X-ray film cartridge (20), and in the side areas, when guided by the straight sections (31S) of the drive and guide groove (31), the rotary frame (11) simulataneously turns around both journal pins (13, 51) or similar of the crank mechanism (13, 50, 51).

Claim 4

An apparatus in accordance with claims 1 or 2, characterized in that a guiding block, preferably a guide wheel (39), is installed to interact with said drive wheel (40), which guide wheel (39) is installed in association with the rotary frame (11), preferably coaxially with the rotary axis of the drive wheel (40), and that said guiding block (39) is arranged to lean against that side of the drive and guide groove (31) which is opposite to the driving point (D) of the drive wheel (40).

Claim 5

An apparatus in accordance with one of claims 1 to 3, characterized in that both opposite journal pins (13, 51) of said crank (50) have two opposite bevelled ball bearings (12a, 12b; 53a, 53b) or equivalent conical ball bearings, preferably preloaded to be completely play-free in such a way as to simultaneously carry both the axial loadings due to the weight of the equipment and the radial forces during the rotation.

Claim 6

An apparatus in accordance with one of claims 1 to 4, characterized in that said guide and drive groove (31) is arranged to open to the underside of said fixed frame (30), and that for interaction with said groove (31) such a drive and guide device is arranged into the rotary frame (11) that comprises a drive unit (33) turning around a vertical axis (38), in which drive unit (33) there is a spring element (35) or similar for loading the drive wheel (40) against the outer edge of said groove (31), and that a protruding part (llc) is fastened to the rotary frame (11), to which protruding part a guide wheel (39), coaxial with said drive wheel (40), is fastened, said guide wheel (39) being installed to lean against the vertical side of the drive and guide groove opposite to the touching point (D) of the drive wheel (40).

Claim 7

An apparatus in accordance with one of claims 1 to 5, characterized in that in said drive and guide groove (31) there is a bottom section (31b) functioning as the guide groove and a broader outer section (mouth section) (31a), which functions as the drive groove and is slightly broader than the diameter of the drive wheel (40).

Claim 8

An apparatus in accordance with one of claims 1 to 6, characterized in that the journal pin (38) and the spring element (35) of said drive unit (33) are arranged on the opposite sides of the passing point of the X-ray (X) so that said spring element (35) loads said unit (33) towards the X-ray film cartridge (20) and towards the outer side of the guide groove (31a).

Claim 9

An apparatus in accordance with one of claims 1 to 7, characterized in that said crank mechanism (13, 50, 51) comprises a counter-profile (42) fastened to the top side of the rotary frame (11) that turns, when the crank is in its middle position, under the crank, and a guide profile (43) fastened to the opposite bottom side of the fixed frame (30), which profiles (42, 43) have symmetrical guide surfaces (42a, 42b) being in the center position of the rotary frame (11) and in said center plane (C-C), symmetrically with regard to said center plane (C-C), which guide surfaces (42a, 42b) are, in the above positon, concentric with the rotary axis (0 2 ) of the X-ray-film-side journal pin (51), and which guide surfaces precicely determine the position of the instantaneous rotary centre in the curved middle area of the drive and guide groove (31), and that the straight side (42b) of said counter-profile (42) and the curved side of said guide profile (43), when touching each other, move the rotary centre thus increasing the turning radius of the rotary frame (11).

Claim 10

An apparatus in accordance with one of claims 1 to 8, characterized in that said crank (50) is connected to a spring element (55), which ensures the mutual supporting contact between the guiding surface (42b) of the counter-profile (42) and the curved guiding surface of the guide profile (43) and the exact location and smooth moving of the rotary centre of the rotary frame (11) from the front journal pin (51) of the crank towards the side.

Claim 12

An apparatus in accordance with one of claims 1 to 10, characterized in that said drive wheel (40) and guide wheel (39) are coaxially positioned on the same vertical shaft so that the rotary frame (11) may move without any axial loading disturbing the smooth, play-free and jerkless drive of the drive wheel (40).

Claim 13

An apparatus in accordance with one of claims 1 to 11, characterized in that said drive device and said crank mechanism are so interassembled that the turning mechanism of the rotary frame (11) operate without practically any play or jerks.