PURPOSE: To remove residual charge and to take out high output signal current in a signal read out field by reading out signals over n fields after numerical open/close field of an optical chopper.
CONSTITUTION: A relation between an open/close period of the optical chopper and the field is shown in Fig. a, which indicates that fields 1∼8 correspond to the open and fields 9∼16 correspond to the close. At the position of Fig. b, signal reading out is performed and a generated charge in each field becomes as shown in Fig. c, where an effective signal reading out field is set at the fields No.6 and No.14, and signal reading is performed up to the field immediately before the open/close chopper. In this method, residual charges +Q1, -Q1, +Q2, -Q2 are read out in the fields No.7, 8, and No.15 and 16 and then removed, remaining only the residual charges +Q3 and -Q3. These residual charges +Q3 and -Q3 are so slight that high output signal current will be obtained at the time of the open/close of the chopper.
FUMOTO TERUO
KANEKO AKIRA
NISHIDA JIYUN
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