Phototiming control method and apparatus
US4748649A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 4, 1986 |
| Grant date | May 31, 1988 |
| Priority date | — |
| Expiry date | Aug 4, 2006 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH05G1/46
- WIPO fieldMedical technology
- WIPO sectorInstruments
Abstract
An improved phototimer control and compensation scheme is provided. The control monitors electrical signals produced by a plurality of photomultiplier tubes. PMT dark current is sampled prior to exposure and is compensated for as exposure begins. Each PMT produces a signal proportional to incident radiation which is integrated by separate integrator means to produce first ramp signals. Switching means are provided for selecting any one or combination of first ramp signals. Mixing means combines selected first ramp signals. Amplifier means amplifies mixed signals as a function signals selected to produce a second ramp signal. Gain selection means compensates the gain of the second ramp signal to the speed with the film-screen combination chosen. An exposure compensation scheme produces an exposure reference signal defining the net effect of system variables. Equations defining kV reference curves are stored in a first storage means. Digital data values representing characteristics of different film-screen combination are stored in a second storage means. A processor develops a kV ramp reference signal base on one of the kV reference curves and data values. Scaling factor equations a…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.