Analytical centrifuge with improved signal/noise ratio

• US 4,226,537 A
• Filed: 03/30/1979
• Issued: 10/07/1980
• Est. Priority Date: 04/15/1978
• Status: Expired due to Term

• Current Assignee: Fisons Limited (Sanofi )
• Original Assignee: Fisons Limited (Sanofi )
• Inventors: Colley, Edward E. S.
• Primary Examiner(s): Corbin, John K.
• Assistant Examiner(s): Arnold, Bruce
• Application Number:
  US06/025,323
• Time in Patent Office: 557 Days
• Field of Search: 356/426-428, 356/151, 356/152, 422/72
• US Class Current: 356/427
• CPC Class Codes: B04B 13/00 Control arrangements specially designed for centrifuges; Programme control of centrifuges control arrangements for feed, charge, or discharge B04B11/00
• CPC Class Codes: G01D 18/00 Testing or calibrating apparatus or arrangements provided for in groups G01D1/00 - G01D15/00

Abstract

Valid signals from a cell in a centrifuge rotor are distinguished from extraneous signals by passing the signals through circuits which compare the amplitude and duration of the signal with the minimum expected values for those signals. Signals having the desired amplitude and duration are passed to the appropriate recorder which can be selected by a switching mechanism actuated by a circuit triggered at the release of the signal from the duration comparison circuit. The duration comparison circuit counts signals emitted from the rotor as it rotates and hence will operate over a wide range of speeds of rotation.

Claims

1. A centrifuge assembly provided with means for determining the speed of angular rotation of the rotor and the angular orientation of the rotor and for measuring a characteristic of a material in a cell carried by the rotor characterised in that it is provided with means for comparing the amplitude and duration of signals generated from a cell being scanned with a desired amplitude and with the angular length of the cell being scanned and for rejecting signals which are of smaller amplitude and of shorter angular duration than the signals expected for the cell being scanned.

2. A centrifuge assembly as claimed in claim 1 adapted for operation with split cells and wherein the comparison means is adapted to actuate means for separately recording the signals from each portion of the split cells.

3. A centrifuge assembly as claimed in claim 1 comprising a means for counting signals from the rotor to determine the time taken for the rotor to rotate through the angular duration of the cell whose signal is to be monitored, which means is capable of comparing that duration with the duration of the signal being monitored and of passing that signal to a recording or measurement means only if it is of the desired duration.

4. A centrifuge assembly as claimed in claim 1 wherein the rotor is provided with a series of marks and means for scanning the marks to provide a series of signals corresponding to the speed of angular rotation of the rotor;

means for multiplying these signals so as to provide a series of secondary signals each corresponding to an angular rotation which is a submultiple of the angular duration of the portion of the cell whose signal is to be monitored; and

counting means for counting the secondary signals up to a total corresponding to the angular duration and for comparing the duration of the observed signal from the cell with that count, the counting means being capable of actuating switch means to pass a signal from the cell having the desired amplitude and duration to a recording or measurement means.

5. A centrifuge as claimed in claim 4 wherein the counting means is a shift register receiving signals from the cell via an amplitude comparison means and from the rotor mark scanning means, which shift register is connected to a second shift register adapted to switch the signal from the cell to a second recording or measurement means upon termination of the signal from the first portion of a split cell.

6. A method for discriminating valid first signals from a sample carried by a component of a centrifuge rotating about an axis thereof, which method comprises generating a second series of signals having a duration proportional to the angular speed of rotation of the component and proportional to the duration of a valid first signal;

comparing the amplitude and duration of the first signals with the expected amplitude of a valid first signal and with the duration of a valid signal as expressed by said second series of signals; and

rejecting signals which are not of the desired duration and amplitude.

7. A method as claimed in claim 6 wherein the component is the rotor of the centrifuge.

8. A method as claimed in claim 6 wherein the centrifuge rotor carries two series of marks which are independently scanned by separate scanners, the first series of marks serving to trigger the scanning of the second series of marks at a given orientation of the rotor, the signals from the second series of marks providing said second series of signals and being passed to a counter mechanism which is adapted to count the number of said second signals corresponding to the angular duration of a valid first signal and which also counts the first signals for the same duration and which passes said first signals only if they satisy the count.

9. A method as claimed in claim 6 wherein the first series of signals are generated by the diffraction of a light beam passing through a cell carried by the rotor.