X-ray or gamma ray systems or devices – Photographic detector support – For movable film or plate
Patent
1989-11-08
1991-09-17
Fields, Carolyn E.
X-ray or gamma ray systems or devices
Photographic detector support
For movable film or plate
378167, 378182, G03B 4204
Patent
active
050502034
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a device for positioning X-ray film cassettes of different widths by means of two parallelly guided members movable toward and away from each other in a cassette loading and unloading apparatus.
BACKGROUND ART
A centering device of this general type is disclosed in U.S. Pat. No. 3,150,263, issued Sept. 22, 1964 (FIG. 5). The centering device therein disclosed comprises two pneumatically operated crank disks connected together and rotating in opposite directions, each disk being associated with a guide by means of a pair of parallelly pivoted links.
In another cassette positioning device as disclosed in DE-OS 30 00 760, Offenlegungstag July 16, 1981, shifting movement of guide members is accomplished by a motor driven worm gear.
Both of these prior devices are disadvantageous in that the centering and alignment of a film cassette is effected by an abrupt and unabsorbed impact of the guides against the side walls of the cassette. Furthermore, there is no provision for compensating for overtravel of an electric motor in the second device. Moreover, in the case of the first-mentioned device, cassettes of larger sizes can only be precisely and reliably aligned and centered by means of an additional sliding guide engaging the rear end of the cassette and transporting the cassette over the last portion of its path to the loading and unloading station.
DISCLOSURE OF THE INVENTION
The present invention provides a centering device of simple construction that is reliable and precise in operation, in which the impact of the guides against the edges of the cassette is attenuated and wherein the motor moving the bars is switched off at a given point and overtravel of the motor is compensated, such that undue pressure against the edges of the cassette is avoided.
Such operation is achieved by a lever arrangement for moving the guide members, said arrangement being actuated by a power driven link pivotally attached to it and consisting of link portions movable with respect to each other in a telescoping manner, with a force absorbing connection between the link portions, for example, a spring, which urges the link portions to maximum extended position with respect to each other.
In further detail, the link portions telescope together when the guide members abut against the edges of a cassette, the telescoping taking place against the resistance of biasing means. The telescoping movement is arranged such that in a first section of this movement, control means for the power source is actuated, while continued movement to a second section compensates for overtravel of the power source.
As a result of this ingenious arrangement, the bias resisted telescoping of the link portions buffers the impact of the guide members against the edges of the cassette when aligning and centering takes place, yet the cassette is precisely aligned, free from play. The power source is switched off while the guide members are still being shifted together and overtravel of the motor is compensated, thus avoiding clamping the guide elements too tightly against the cassette.
The guide members are conveniently made at least as long as a cassette of maximum size, and the members are guided in their movement by a guide rod as well as guide rails. The free ends of the guide members extend into the interior of the apparatus and are provided with guide grooves.
The invention is shown in a preferred embodiment in the appended drawings which are described below. In the drawings;
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1 and 2 are plan views showing the apparatus in two functional positions;
FIG. 3 shows a detail of the construction in a sectional view along line II--II;
FIGS. 4 and 5 are plan veiws corresponding to portions of FIGS. 1 and 2, respectively; and
FIG. 6 is a sectional view taken on line IV--IV of FIG. 4.
MODES OF CARRYING OUT THE INVENTION
Referring now to FIG. 1, there is shown apparatus 1 for unloading film sheets from X-ray film cassettes of different sizes and loading such cassettes wit
REFERENCES:
patent: 2097402 (1937-10-01), Flarsheim
patent: 3150263 (1964-09-01), Catlin
patent: 4538293 (1985-08-01), Cutter
patent: 4539696 (1985-09-01), Walling et al.
patent: 4675894 (1987-06-01), Ohlson
patent: 4760589 (1988-07-01), Siczek
Killguss Heinz
Mirlieb Bernd
Childress G. Herman
Eastman Kodak Company
Fields Carolyn E.
Porta David P.
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