Apparatus to register the quantity of sebum secreted by a skin
US4480921A · kind A · utility
10Cited by
7References
12Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Apr 6, 1979 |
| Grant date | Nov 6, 1984 |
| Priority date | — |
| Expiry date | Apr 6, 1999 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N21/274
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Method and apparatus to measure the quantity of sebum secreted by the skin, by passing light through the specimen. The light passed through the specimen is modulated at a predetermined frequency, and only light of the same modulated frequency is measured by a receiver. The apparatus includes automatic zero calibration, and several embodiments of stabilized phototransistor circuits.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.