Controlled temperature hair dryer
US4260875A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 19, 1978 |
| Grant date | Apr 7, 1981 |
| Priority date | — |
| Expiry date | Jun 19, 1998 |
Classification
- Technology area (CPC A)Human Necessities
- CPC primaryA45D20/12
- WIPO fieldOther consumer goods
- WIPO sectorOther fields
Abstract
A hair dryer, the temperature of the air stream from which is automatically controlled by the temperature of the hair being dried, is provided. The dryer includes a primary air inlet, a fan for blowing inlet air out of the dryer, and a heater by which the blown air is heated before it is directed against a user's hair. The dryer also includes a feedback air duct and a thermistor positioned in the duct to sense the temperature of the air being reflected off the user's hair as it is dried. In accordance with the temperature of the reflected air, the thermistor changes resistance, which change is sensed by an integrated circuit zero crossing switch that electronically signals a thyristor causing the thyristor either to switch off or proportionally reduce the power to the heater, and therefore the amount of heat energy input in the blown air. Consequently, the temperature of the air being blown against the user's hair is continuously monitored as the hair dries to avoid the hair and scalp from becoming overheated.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.