Patent US4493643A successfully refreshed from Google Patents.
US4493643A
Expired / Lapsed
US
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Dental handpiece having non-contact rotational speed detection device
Assignee: J Morita Manufaturing Corp
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Filing: 1982-12-30
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Granted: 1985-01-15
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Expires: 2002-12-30
Abstract
Abstract A dental handpiece having therein a non-contact rotating speed detection device which includes an electromagnetic induction pulse generator including a permanent magnet provided close to the rotor in the head of a dental handpiece and a coil wound around the permanent magnet, and a rotor made of a magnetic material provided with recesses and/or projections around its circumference. The handpiece according to the invention facilitates to accurately detect rotor speed by detecting a pulse voltage proportionate to the rotation speed and therefore is useful for dental treatment and experiments.
Inventors
- 👤 Akifumi Tachibana
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 04:13
CPC Classifications
A; A61; A61C; A61C1/00; A61C1/0007; A61C1/0038; A61C1/08; A61C1/0015; A61C1/003
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
80 words
A dental handpiece having therein a non-contact rotational speed detection device, which device comprises: cylindrical rotor made of a magnetic material provided with discontinuities around its circumference: and an electromagnetic induction pulse generator comprising a permanent magnet provided close to said cylindrical rotor in a head of said dental handpiece and a coil wound around said permanent magnet, whereby the pulse generator generates an induction voltage proportionate to the product of the number of said discontinuities and the rotational speed;
Claim 2
Dependent Claim
80 words
A dental handpiece having therein a non-contact rotational speed detection device, which device comprises: cylindrical rotor made of a magnetic material provided with discontinuities around its circumference: and an electromagnetic induction pulse generator comprising a permanent magnet provided close to said cylindrical rotor in a head of said dental handpiece and a coil wound around said permanent magnet, whereby the pulse generator generates an induction voltage proportionate to the product of the number of said discontinuities and the rotational speed;
Claim 3
Dependent Claim
78 words
A dental handpiece as claimed in claim 1, wherein said discontinuities are a pair of chamfered sections formed symmetrically relative to the rotational axis center at a lower end portion of said cylindrical rotor and wherein said permanent magnet has a semicircular shape, includes said coil would around a central section so that the N and S poles are symmetrical relative to the rotor axis center, and is provided close to the circumference of said lower end portion.
Claim 4
Dependent Claim
69 words
A dental handpiece as claimed in claim 1, wherein projections are provided on a circumferential section of a lower end portion of said cylindrical rotor and wherein said permanent magnet has a semicircular shape, includes said coil wound around a central section so that the N and S poles are symmetrical relative to the rotor axis center, and is provided close to the circumference of said lower end portion.
Claim 5
Dependent Claim
22 words
A dental handpiece as claimed in claim 2 or 3, wherein said permanent magnet is fixed in the head with an adhesive.
Claim 6
Dependent Claim
24 words
A dental handpiece as claimed in claim 2 or 3, wherein said permanent magnet is fixed in the head by a coned disc spring.
References Cited (Backward Citations)
US4153993A
Cited
US4288746A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-01-15 | 1988-07-16 | 1989-01-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-01-15 | 1992-07-16 | 1993-01-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-01-15 | 1996-07-16 | 1997-01-15 | $7700.00 | Window Closed / Lapsed |