US4968953A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Oscillation circuit for proximity switch
Assignee: Omron Corp
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Filing: 1989-11-22
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Granted: 1990-11-06
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Expires: 2009-11-22
Abstract
Abstract An oscillation circuit of a proximity switch includes a parallel LC resonance circuit (L, C), an oscillation transistor (Tr6) controlled by an output voltage from the resonance circuit for switching a constant current and a feedback circuit (Tr2, Tr3) for feeding back a current flowing through the oscillation transistor to the resonance circuit. In the circuit, there is further disposed a feedback current increase circuit including a second transistor (Tr7) controlled by an output voltage from the resonance circuit and a resistor (R) connected in series to the second transistor. The resonance circuit is supplied via the feedback circuit with a feedback current obtained by adding a current flowing through the feedback current increase circuit and a current passing through the oscillation transistor, thereby developing a large change in the amplitude of the oscillation.
Inventors
- 👤 Yoshimi Kanda
- 👤 Akio Matsumoto
- 👤 Yasushi Matsuoka
- 👤 Tsutomu Ajioka
- 👤 Hirofumi Endo
- 👤 Satoshi Motouji
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 20:14
CPC Classifications
H; H03; H03K; H03K17/00; H03K17/94; H03K17/945; H03K17/95; H03K17/952; H03K17/9537; H03K17/9542; H03K17/9547; H03B; H03B5/00; H03B5/08; H03B5/12; H03B5/1203; H03B5/1231; H03B5/1237; H03B5/1293; H03B5/1296; H03B2200/00; H03B2200/003; H03B2200/0038
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
189 words
An oscillation circuit cf a proximity switch comprising: (a) a constant current mirror circuit; (b) an oscillation transistor for switching an output current from said constant current mirror circuit; (c) a parallel resonance circuit including a sense coil and a capacitor in parallel; (d) a current mirror circuit for feeding back a current flowing through said oscillation transistor to said parallel resonance circuit; (e) a direct-current bias generator circuit; (f) a bias circuit connected to said direct-current bias generator circuit and said parallel resonance circuit for supplying a bias voltage to said oscillation transistor, said oscillation transistor being controlled by a voltage developed by said bias circuit; and (g) a feedback current increase circuit including a feedback current increase transistor controlled by a voltage developed by said bias circuit and a resistor connected in series to said feedback current increase transistor, said feedback current increase circuit being connected in parallel to said oscillation transistor, a current obtained by adding a current flowing through said feedback current increase circuit to a current flowing through said oscillation transistor being fed back via said current mirror circuit to said parallel resonance circuit.
Claim 2
Dependent Claim
189 words
An oscillation circuit cf a proximity switch comprising: (a) a constant current mirror circuit; (b) an oscillation transistor for switching an output current from said constant current mirror circuit; (c) a parallel resonance circuit including a sense coil and a capacitor in parallel; (d) a current mirror circuit for feeding back a current flowing through said oscillation transistor to said parallel resonance circuit; (e) a direct-current bias generator circuit; (f) a bias circuit connected to said direct-current bias generator circuit and said parallel resonance circuit for supplying a bias voltage to said oscillation transistor, said oscillation transistor being controlled by a voltage developed by said bias circuit; and (g) a feedback current increase circuit including a feedback current increase transistor controlled by a voltage developed by said bias circuit and a resistor connected in series to said feedback current increase transistor, said feedback current increase circuit being connected in parallel to said oscillation transistor, a current obtained by adding a current flowing through said feedback current increase circuit to a current flowing through said oscillation transistor being fed back via said current mirror circuit to said parallel resonance circuit.
Claim 3
Dependent Claim
110 words
An oscillation circuit of a proximity switch comprising : a parallel LC resonance circuit; an oscillation transistor controlled by an output voltage from said resonance circuit for switching a constant current; a feedback circuit for feeding back a current flowing through said oscillation transistor to said resonance circuit; and a feedback current increase circuit including a second transistor controlled by an output voltage from said resonance circuit and a resistor connected in series to said second transistor; said resonance circuit being supplied via said feedback circuit with a feedback current obtained by adding a current flowing through said feedback current increase circuit and a current passing through said oscillation transistor.
Claim 4
Dependent Claim
110 words
An oscillation circuit of a proximity switch comprising : a parallel LC resonance circuit; an oscillation transistor controlled by an output voltage from said resonance circuit for switching a constant current; a feedback circuit for feeding back a current flowing through said oscillation transistor to said resonance circuit; and a feedback current increase circuit including a second transistor controlled by an output voltage from said resonance circuit and a resistor connected in series to said second transistor; said resonance circuit being supplied via said feedback circuit with a feedback current obtained by adding a current flowing through said feedback current increase circuit and a current passing through said oscillation transistor.
References Cited (Backward Citations)
US4761603A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1993-11-05 | 1994-05-07 | 1994-11-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-11-05 | 1998-05-07 | 1998-11-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-11-05 | 2002-05-07 | 2002-11-06 | $7700.00 | Window Closed / Lapsed |