公开(公告)号：US3552863A

公开(公告)日：1971-01-05

申请号：US3552863D

申请日：1967-07-28

Applicant: BECKMAN INSTRUMENTS INC

Inventor： SMITH DOUGLAS H

IPC: G01N21/59 ,  G01J1/16 ,  G01N21/22

CPC classification number: G01J1/1626

Abstract: A TRANSMITTANCE TO FREQUENCY CONVERTER WHERE A COMMON LIGHT SOURCE ILLUMINATES A SAMPLE CUVETTE AND A REFERENCE CUVETTE. THE TRANSMITTED LIGHT IS INDIVIDUALLY MEASURED BY TWO PHOTOTUBES. THE TIME AVERAGE OUTPUT CURRENTS OF THE TWO PHOTOTUBES ARE OF OPPOSITE POLARITIES AND ARE COMBINED IN AN INTEGRATING CAPACITOR COUPLED TO A COMPARATOR. THE COMPARATOR IS PART OF FEEDBACK CONTROL LOOP WHICH PROVIDES FOR CONTROL OF THE TIME AVERAGE OF THE REFERENCE CURRENT TO MAKE IT EQUAL TO THE AVERAGE SAMPLE CURRENT. A TRANSISTOR SWITCH CONTROLS THE "ON" TIME OF THE REFERENCE PHOTOTUBE TO THEREBY CONTROL OF THE TIME AVERAGE OF THE REFEENCE CURRENT. THE DUTY CYCLE

OF THE SWITCH IS PROPORTIONAL TO THE TRANSMITTANCE OF THE SAMPLE.

公开(公告)号：US3506818A

公开(公告)日：1970-04-14

申请号：US3506818D

申请日：1966-06-06

Applicant: BECKMAN INSTRUMENTS INC

Inventor： SMITH DOUGLAS H

IPC: G06F17/00 ,  G06G7/186 ,  H03M1/00 ,  G06G7/18 ,  G06F15/20

CPC classification number: G06K9/0053 ,  G06G7/186 ,  H03M1/00 ,  H03M1/124

公开(公告)号：US3335385A

公开(公告)日：1967-08-08

申请号：US38583964

申请日：1964-07-29

Applicant: BECKMAN INSTRUMENTS INC

Inventor： MOWER WILFORD E ,  PEPPER JAMES H ,  SMITH DOUGLAS H

IPC: H01C10/38

CPC classification number: H01C10/38