Automatic spectrophotometer

Claim 2

A spectrophotometer comprising means for emitting a monochromatic light beam; means for alternatively inserting a reference sample and an unknown sample into the path of said light; transducer means positioned to receive the light from the samples for producing an electric output signal corresponding to the intensity of light transmitted through said samples, measuring means coupled to said electric signal producing means for measuring the intensity of the said output signal; a differential amplifier having a first input terminal to receive the output signal of the transducer means, means for periodically intercepting said monochromatic light beam; a first sampling means for sampling the output signal of the differential amplifier during the period of the interception of said light beam; circuit means including a pulse amplifier circuit and a smoothing circuit for supplying a D.C. control voltage to a second input terminal of said differential amplifier from the output signal of said first sampling means; a second sampling means for sampling the output signal of said differential amplifier during the period said light beam is received by said transducer means; means for detecting the interception timing to generate controlling pulse signals and supply where outputs of the transducer means and the standard voltage supply becomes equal, memory means for memorizing output voltage of the variable voltage si second controlling means for controlling said variable voltage supply to attain a second controlled condition where the output of the variable voltage supply becomes equal to the output memorized in said memory means, and switching means for switching from said first controlled condition to said second controlled condition.

Claim 3

A spectrophotometer comprising means for emitting monochromatic light; means for alternatively inserting a reference sample and an unknown sample into the path of said light; a photomultiplier for producing an electric output signal corresponding to the intensity of light directed into it and positioned in said light path to receive light from said samples; a first differential amplifier having a first input terminal to receive said output signal of said photomultiplier; indicating means coupled to said first differential amplifier for indicating the intensity of the output signal of said photomultiplier; means for periodically intercepting said monochromatic light beam; a first sampling means for sampling the output signal of said first differential amplifier during the period of the interception of said light beam; circuit means including a pulse amplifier circuit and a smoothing circuit for supplying a D.C. control voltage to a second input terminal of said first differential amplifier from the output signal of said first sampling means; a second sampling means for sampling the output signal o said first differential amplifier during the period said light beam is received by said photomultiplier; means for detecting the interception timing to generate controlling pulse signals and supply them to said first and second sampling means and said circuit means; a variable voltage supply for supplying high direct correct voltage to the dynodes of said photomultiplier and in which the supply voltage can be varied for the control of the sensitivity of the photomultiplier in accordance with a controlling signal, a second differential amplifier coupled to said voltage supply for supplying a control signal to said variable voltage supply in accordance with the difference between signals applied to input terminals thereof; a standard voltage source coupled to said second differential amplifier for supplying standard voltage to a First input terminal thereof for adjusting the sensitivity of said photomultiplier to a standard sensitivity when said reference sample is inserted in said light path; connecting means connecting the photomultiplier to a second terminal of said second differential amplifier for applying thereto a voltage based on the output of said photomultiplier during a calibration period when said standard voltage is applied to said first terminal thereof; capacitor means; and switching means connecting said capacitor means to the output terminal of said variable voltage supply during the calibration period for memorizing output voltage of the variable voltage supply during said calibration period and connecting said capacitor and the output terminal of said variable voltage supply to the input terminals of said second differential amplifier and disconnecting said standard voltage source and said connecting means from said terminals during the measuring period when said unknown sample is placed in the light path instead of the reference sample.

Claim 4

A spectrophotometer comprising means for emitting monochromatic light; means for alternatively inserting a reference sample and an unknown sample into the path of said light; a photomultiplier for producing an electric output signal corresponding to the intensity of light directed into it and positioned in said light path to receive light from said samples; a first differential amplifier having a first input terminal to receive said output signal of said photomultiplier; indicating means coupled to said first differential amplifier for indicating the intensity of the output signal of said photomultiplier; means for periodically intercepting said monochromatic light beam; a first sampling means for sampling the output signal of said first differential amplifier during the period of the interception of said light beam; circuit means including a pulse amplifier circuit and a smoothing circuit for supplying a D.C. control voltage to a second input terminal of said first differential amplifier from the output signal of said first sampling means; a second sampling means for sampling the output signal o said first differential amplifier during the period said light beam is received by said photomultiplier; means for detecting the interception timing to generate controlling pulse signals and supply them to said first and second sampling means and said circuit means; a variable voltage supply for supplying high direct correct voltage to the dynodes of said photomultiplier and in which the supply voltage can be varied for the control of the sensitivity of the photomultiplier in accordance with a controlling signal, a second differential amplifier coupled to said voltage supply for supplying a control signal to said variable voltage supply in accordance with the difference between signals applied to input terminals thereof; a standard voltage source coupled to said second differential amplifier for supplying standard voltage to a First input terminal thereof for adjusting the sensitivity of said photomultiplier to a standard sensitivity when said reference sample is inserted in said light path; connecting means connecting the photomultiplier to a second terminal of said second differential amplifier for applying thereto a voltage based on the output of said photomultiplier during a calibration period when said standard voltage is applied to said first terminal thereof; capacitor means; and switching means connecting said capacitor means to the output terminal of said variable voltage supply during the calibration period for memorizing output voltage of the variable voltage supply during said calibration period and connecting said capacitor and the output terminal of said variable voltage supply to the input terminals of said second differential amplifier and disconnecting said standard voltage source and said connecting means from said terminals during the measuring period when said unknown sample is placed in the light path instead of the reference sample.

Claim 5

A spectrophotometer as claimed in claim 2 wherein the variable voltage supply comprises a transistorized push-pull oscillator having a pair of transistors and an oscillation level controlling transistor inserted in the collector circuit of said pair of transistors.

Claim 6

A spectrophotometer as claimed in claim 2 wherein said means for alternately inserting said cells in the path of said light is connected with said switching means so that said switching means is actuated when said cells are changed. for coupled signal, amplifier having periodically of differential from sampling means, period transducer means,