Helena Laboratories Corporation

Samuel Rhine

Gene A Butts

An optical system is disclosed for a densitometer which scans an electrophoretically separated sample and provides an output signal for graphical display indicative of the optical density of the scanned sample. The optical system provides storage for a plurality of filter assemblies selectively used depending on the mode of densitometry scanning. It includes a turret assembly, a detector housing, and a lamp support to permit an operator convenient selection capability of a desired filter when scanning in either visible or fluorescent modes of operation. A plurality of optical density and blocking filters are sandwiched between turret plates at spaced radial positions. The plates have aligned openings adjacent to the filter areas to permit light to pass through the filters for detection. Turret barrels and slit assemblies are mounted on one of the plates above the filters to protect the photo-responsive detector from stray light which may be present and to optimize the sensitivity and resolution of the electrophoresis patterns. The plate-filter sandwich unit is rotatably mounted above the detector such that the individual filters are selectively rotated into a position directly above and in alignment with the detector. The turret assembly includes an indexing mechanism and control arrangement to insure that only the visible light source is on when certain filters are above the detector and only the ultra-violet light source is on when other filters are above the detector. A sight alignment and override feature is provided in the optical system such that when the door to the densitometer is open, both the visible and fluorescent light sources are on. Under these conditions, light sources assist the operator in aligning the sample for scanning. Another part of the invention resides in the collimating slit assemblies mounted on the turret assembly which are used for defining the amount of light and the area of the sample seen by the detector in the fluorescent mode.

Optical system for densitometer

An improved paper tensioning device, for use with a chart recorder or densitometer of the type where the paper is tightly wound around a hollow core, which paper tensioning device prevents the chart paper from unwinding too fast. The paper tensioning device comprises a rod and plug combination with the plug secured to one end of the hollow core and with the rod being inserted through the hollow core, from the other end thereof, to mate with the plug. Axial pressure on the rod is maintained to cause a constant drag on the hollow core and on the chart paper. The plug and hollow core may be an integrally formed unit onto which the paper is wound. Optionally, the rod and plug may be a one piece unit or the rod, plug and core may be a one piece unit.

Paper tensioning device

In a chart recorder where a print head is used to record data on a moving strip of chart paper, an improved apparatus for biasing the print head against the moving chart paper. The biasing apparatus provided includes a cantilevered leaf spring to maintain a constant and preset pressure between the print head and the moving chart paper. The distal or fixed end of the leaf spring is anchored to the frame of the chart recorder and the print head is mounted on the free end of the cantilevered leaf spring so that the leaf spring maintains a constant pressure between the print head and the moving chart paper. The cantilevered spring is adjustable to provide the desired amount of pressure between the print head and the moving chart paper. When a new roll of chart paper is inserted into the chart recorder, the cantilever spring re-establishes and maintains the pressure between the print head and the new roll of chart paper.

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Beaumont, TX, United States of America

Samuel Rhine