Hitachi, Ltd.

Kiwao Seki

Tsuyoshi Nishitarumizu

Koji Tsutsuta

Taro Nogami

Sadabumi Ohnuma

Koji Nishiwaki

Touhachi Yoshihara

In a liquid chromatographic analyzer apparatus, there is possibility that a flow cell is damaged when a flow passage is blocked and the inner pressure is increased. In order to prevent damage to the apparatus, liquid is prevented from leaking inside the apparatus. The liquid is discharged externally through a liquid discharging tube. A spring member is provided between the flow cell and the seal in a tube connecting portion to allow liquid to leak when the pressure is increased. Further, a light-proof tube for blocking light is connected to the flow cell to allow the leaked liquid to flow through the light-proof tube.

Liquid analyzing apparatus

An electrical conductivity measuring apparatus for measuring the electrical conductivity of liquid has a plurality of electrodes disposed in the liquid contained in a measuring cell, with an a.c. voltage being applied between the electrodes, thereby measuring the electrical conductivity by measuring a current flowing between the electrodes. The apparatus includes a reference a.c. voltage source including adjustment means for varying the magnitude and phase of the signal current, and is designed to cancel the conductivity of background by adding the current from the reference a.c. voltage source to the current from the electrodes.

Apparatus for measuring electrical conductivity

A conductivity detector includes an A.C. voltage supply and control circuit for applying a pair of electrodes disposed within a cell filled with electrolyte with a predetermined A.C. voltage and a correction signal generating circuit for generating a A.C. reference signal. At an auto zero adjustment operation, an output A.C. current signal flowing through the electrolyte is detected and the A.C. current is added to the A.C. reference signal. In advance of measuring conductivity, the amplitude of the A.C. reference signal is corrected until the resultant signal of the A.C. output current and the A.C. reference signal reduces to zero.

Conductivity detector

A low pulsation displacement pump has a pair of plungers and motor driven-cams or feed screws for reciprocating the plungers. In order to cause the pump to stably discharge a liquid so that variation in discharge due to machining errors of the plungers or the feed screws is eliminated, the pump discharge pressure is measured at each of a plurality of predetermined operative positions of the plungers before delivery of the pump from a manufacturing plant, and machining errors are obtained in accordance with the thus-measured discharge pressure. Then, the speed correction factor for the motor is calculated for each of the plurality of predetermined positions of the plungers in accordance with the thus-obtained errors to store the results of the calculation in a memory. When the pump is used, the motor is operated while the speed of the motor is compensated for at each of the plurality of predetermined positions of the plungers in accordance with the speed correction factor stored in the memory, whereby the rate of discharge of pump can be kept substantially constant by preventing speed variation of the plungers due to machining error of the cams.

Low pulsation displacement pump

A low pulsation pump device has a pulse motor, two plungers adapted to be driven by the pulse motor, a pressure sensor disposed on the output side of the plungers, a storage for storing values of pressures detected by the pressure sensor during each of a number of periods, a high speed region during which the rotational speed of the pulse motor is increased. The pulse control has an optimization function which determines, on the basis of pressure information which was obtained during the last period, the location of a high speed region in each period in such a manner as to reduce pulsations.

Low pulsation pump device

The present invention divides the light to be measured, which is incident to a photo-detector having a plurality of photo-cells from a light source through a specimen to be measured and through a dispersion element, into a wavelength of a high sensitivity region and a wavelength of a low sensitivity region, reads out the light of the high sensitivity wavelength region with a quicker period than the light of the low sensitivity wavelength region, and adds the signals thus read out for each wavelength region in order to obtain spectra for the full wavelength.

Spectrophotometer

The data processing apparatus according to this invention comprises a microprocessor and a dot printer. The printer is of such a type that the printing paper is stepwise advanced each time a line of characters are printed. The analog signal from the detector of a chromatograph is converted to a corresponding digital signal. A block of data values to be printed on one line, separated from the digital signal corresponding to the waveform pattern varying with time, is stored in a print buffer memory. The stored data values are printed out in dot matrix form. The emptied buffer memory then stores another block of data values to be plotted on the next line. Thereafter, the plotting and storing operations are repeated until a chromatogram is completed. The concentrations of the components corresponding to the peaks of the chromatogram are also calculated by processing the digital signal and the result of the calculation is printed out in the form of characters each composed of plural dots by the same printer. Thus, the chromatogram consisting of the respective component peaks and the annotating characters representing the calculated concentrations of the components can be printed on the same paper by the same printing means.

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Katsuta, Japan

Kiwao Seki