Film strip for rapid test of a film processor

Details

Inventors: Shaber, Gary S.; Buenzli, Jr., Charles W.;
Assignee: Probex, Inc. (Villanova, PA)
Primary Examiner: Turk; Arnold
Assistant Examiner:
Attorney, Agent or Firm: Ratner & Prestia

Apparatus and test film strip for evaluation of a film processor, particularly an x-ray film processor, based on a photodetector signal sequentially indicating the optical density of graded density test areas on a developed film and comparing the output thereof to a preselected voltage relating to the acceptable/too dark threshold of an unexposed or base fog area, the acceptable or too light threshold of a maximum density or dark area and the acceptable/too light and acceptable/too dark threshold of a medium density test area. Sequence testing of the graded density areas is functionally related on a single film strip to timing marks, adapted to be read by photodetector and timing circuitry, the timing marks and graded density test areas being linearly spaced and relatively disposed along the length of film strip.

DETAILED DESCRIPTION OF THE INVENTION FIG.
1 is a layout view of a film test strip in accordance with the present invention; FIG.
2 is a circuit diagram depicting, for explanation purposes, an elementary version of the analog circuitry of the actual photodetector circuit shown in the schematic diagram of FIG.
5; FIG.
3 illustrates the circuit of FIG.
2 in the sample mode; FIG.
4 shows the circuit of FIG.
2 in the hold mode; FIG.
5, as indicated previously, is a schematic diagram of the photodetector circuit of the present invention; FIG.
6 is a schematic diagram showing the major components of the sequencing circuitry in the x-ray processor test apparatus of the preferred embodiment of the present invention; FIG.
7 is a schematic diagram of the decode logic and circuitry for the output indications in the apparatus of the preferred form of the present invention; and FIG.
8 is a circuit diagram of the power supply circuit in the preferred embodiment shown in the previous figures.
In general, the x-ray film processor checker of the present invention, also referred to as an x-ray densitometer, in the preferred embodiment of the present invention, measures three exposed areas on a strip of x-ray film and compares their density with pre-set limits.
Combinations of these comparisons illuminate appropriate combinations of light emitting diodes on the front panel of the unit indicating the operational status of the processor used in developing the film.
The range of densities covers approximately three orders of magnitude and the desired precision of measurement is approximately 1/2 of 1% of the density measured.
In accordance with the present invention, this is accomplished by a unique ratiometric measurement system.
This ratiometric x-ray densitometer continuously establishes a 100% transmission point when no film is in the reader.
When a film strip is detected entering the reader, the 100% transmission level is stored by a sample and hold circuit.
The four density levels are established by a precision resistor divider from the 100% transmission reference

Related patents

	Novel palladium-based alloys containing tin and their use in the glass industry What is claimed is: 1. A spinneret for contacting molten glass free from oxides less stable than tin oxide, in a glass processing installation, a part of said spinneret ...
	Cell lines and their use for the production plasminogen activators OF THE INVENTION Production of serum-independent human cell lines The present invention provides new human cell lines which grow in the absence of serum or of any ...

0.034
Archive: All patents - Links Copyright (c)2006 Eipa-patents.org - All rights reserved