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US 2003/0142305 A1Published application
Spectrophotometer
AssigneeShimadzu Corporation
InventorHajime Bungo
Life of this patent
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Abstract
In a spectrophotometer, a photodiode detects light transmitted through a sample in a cell. A pre-amplifier and a feedback resistance are connected to the photodiode to convert a small electric current from the photodiode and amplify a voltage thereof. The voltage is read at a CPU after converted to a digital signal at an A/D converter. A sample component is determined from information based on the signal in the CPU. The spectrophotometer includes a circuit for changing the feedback resistance so that the feedback resistance can be adjusted according to the input voltage to the A/D converter.
Claims4
A spectrophotometer, comprising
- a photodiode for detecting light transmitted through a sample in a cell to produce an electric current,
- a pre-amplifier and a feedback resistance, which are connected to the photodiode to convert the electric current from the photodiode to a voltage;
- an A/D converter connected to the pre-amplifier and the feedback resistance for converting the voltage to a digital signal;
- a CPU connected to the A/D converter for reading the digital signal to identify a sample component;
- and
- a circuit connected to the feedback resistance for changing a resistivity of the feedback resistance according to the voltage input to the A/D converter.
3 more elements
Dependencies are inferred from the claim text.