Autozeroing apparatus and method for a computerized tomography data acquisition system
US5177697A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 31, 1990 |
| Grant date | Jan 5, 1993 |
| Priority date | — |
| Expiry date | Aug 31, 2010 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03M1/186
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
An autozeroing apparatus is disclosed for correcting the offset error in a computerized axial tomography (CAT) scanner data acquisition subsystem (DAS). The DAS includes a floating point amplifier for applying discrete amplification factors, or gain range segments, to an analog input before conversion to digital in an A/D converter. A digital autozero circuit is connected to the output of the A/D converter and adds a digital offset value to each A/D converter sample during data acquisition to correct for the net offset errors throughout the DAS. Separate storage latches are included for storing offset values corresponding to each gain range segment, and the offset value used for each sample correction corresponds to the gain range segment used for that sample. During an autozero reference interval, a reference voltage is applied to the DAS and the offset values are updated so as to force the corrected A/D converter output to agree with the reference voltage.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.