Sensor apparatus and safety apparatus for protecting approach to machines
US6376939B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 3, 2000 |
| Grant date | Apr 23, 2002 |
| Priority date | — |
| Expiry date | Apr 3, 2020 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03K2217/96075
- WIPO fieldMechanical elements
- WIPO sectorMechanical engineering
Abstract
A sensor apparatus and a safety apparatus which can ensure significantly enhanced safety by monitoring constantly whether the sensor apparatus is operating normally. An auxiliary electrode plate of a small area is disposed in parallel and in opposition to an electrode plate with a short distance therefrom. A switching element is turned on every second for a period of milliseconds repetitively. When the switching element is turned on under the control of a central processing unit, the auxiliary electrode plate is connected to the ground potential, as a result of which a capacitance &Dgr;C effective between the auxiliary electrode plate and the electrode plate is electrically connected in parallel with a capacitor C0 effective between the electrode plate and a machine component, resulting in that the capacitance C0 is increased by a proportion corresponding to the capacitance &Dgr;C. Consequently, change of the capacitance C0 comparable to that brought about upon detection of the human body takes place, whereby a substantially similar detection signal as the human body detection signal is made available. On the basis of this detection signal, it is possible to monitor whether or not …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.