Patent US4731591A successfully refreshed from Google Patents.
US4731591A
Expired / Lapsed
US
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Inductive proximity switch having switched capacitor for controlling hysteresis
Assignee: Siemens AG
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Filing: 1986-12-12
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Granted: 1988-03-15
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Expires: 2006-12-12
Abstract
Abstract An inductive proximity switch which consists of an oscillator with an externally controllable resonant circuit as well as of a switching amplifier controllable by the oscillator. It further has a feed or biasing circuit for the oscillator and the switching amplifier. Connected in parallel with the capacitor of the resonant circuit is a capacitor with an electronic switch, the electronic switch being responsive to the output of the switching amplifier. Thereby a simple switching hysteresis is obtained.
Inventors
- 👤 Reinhard Weigand
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 15:04
CPC Classifications
H; H03; H03K; H03K17/00; H03K17/94; H03K17/945; H03K17/95; H03K17/952; H03K17/9537; H03K17/954
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
78 words
An inductive proximity switch comprising: a resonator circuit having a resonator frequency and an output which changes in the proximity of an external object, said resonator circuit including a first capacitor; an oscillator coupled to said resonator output and having an oscillator output coupled to means for generating an amplifier output; a second capacitor; and switching means responsive to said amplifier output for switching said second capacitor in parallel with said first capacitor for changing said resonator frequency.
Claim 2
Dependent Claim
78 words
An inductive proximity switch comprising: a resonator circuit having a resonator frequency and an output which changes in the proximity of an external object, said resonator circuit including a first capacitor; an oscillator coupled to said resonator output and having an oscillator output coupled to means for generating an amplifier output; a second capacitor; and switching means responsive to said amplifier output for switching said second capacitor in parallel with said first capacitor for changing said resonator frequency.
Claim 3
Dependent Claim
19 words
The proximity switch of claim 1 wherein said switching means comprises a transistor operated in a common emitter mode.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-03-15 | 1991-09-14 | 1992-03-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-03-15 | 1995-09-14 | 1996-03-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-03-15 | 1999-09-14 | 2000-03-15 | $7700.00 | Window Closed / Lapsed |