Patent US3838324A successfully refreshed from Google Patents.
US3838324A
Expired / Lapsed
US
⏱️ 0.0 years remaining
System for controlling the rotational speed of a micromotor for use in medical instruments
Assignee: J Morita Manufaturing Corp
•
Filing: 1972-01-02
•
Granted: 1974-09-24
•
Expires: 1992-01-02
Abstract
Abstract A system for controlling the rotational speed of a micromotor for use in medical instruments such as a dental handpiece comprises a first transistor connected in series between said motor and a source of electric energy; a second transistor Darlington-connected to said first transistor; a third transistor through which part of the base current of said second transistor flows; circuit means for supplying to said third transistor a base current from the terminal voltage of said motor; a fourth transistor to which part of the current flowing through said second transistor is applied as a base current; and a variable resistor through which both the current caused by the source voltage to flow through said fourth transistor and the current flowing through said third transistor flow, said variable resistor providing a reference voltage for setting the rotational speed of said motor to a predetermined value.
Inventors
- 👤 Y Watanabe
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 19:08
CPC Classifications
H; H02; H02P; H02P7/00; H02P7/06; H02P7/18; H02P7/24; H02P7/28; H02P7/285; H02P7/288; H02P7/2885
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
323 words
A system for controlling the rotational speed of a micromotor which micromotor is responsive to a motor voltage applied to its terminals, comprising: a first transistor connected between said micromotor and a power source, said first transistor controlling the supply of power to said motor; a second transistor Darlington-connected to said first transistor so that upon firing of said second transistor, said first transistor fires, the firing of said second transistor establishing a second transistor collector voltage and the firing of said first transistor establishing a first transistor collector voltage; a third transistor, to which is applied in the base-emitter path the motor voltage applied to said motor, which motor voltage establishes a third transistor base current; a variable resistor coupled at one end thereof to the emitter of said third transistor, the voltage across said resistor being a variable reference voltage; circuit means having a first current flowing therein for providing a base current for said second transistor, which second transistor base current is a portion of said first current, the remaining portion of said first current flowing to the collector of said third transistor, a change in the motor voltage applied to said motor relative to said variable reference voltage causing a corresponding change in the base current of said third transistor and Consequently the base current and collector current of said second transistor, thereby changing the collector current of said first transistor, and hence the motor voltage applied to said motor; and a fourth transistor, having a fourth transistor collector current when conducting, connected between said power source and said one end of said variable resistance, to the base of which fourth transistor is applied a portion of the collector current of said second transistor, said fourth transistor collector current changing accordingly as the load on said motor changes, with a resulting change in said variable reference voltage, thereby resulting in a change in the rotational speed of said motor.
Claim 2
Independent Claim
323 words
A system for controlling the rotational speed of a micromotor which micromotor is responsive to a motor voltage applied to its terminals, comprising: a first transistor connected between said micromotor and a power source, said first transistor controlling the supply of power to said motor; a second transistor Darlington-connected to said first transistor so that upon firing of said second transistor, said first transistor fires, the firing of said second transistor establishing a second transistor collector voltage and the firing of said first transistor establishing a first transistor collector voltage; a third transistor, to which is applied in the base-emitter path the motor voltage applied to said motor, which motor voltage establishes a third transistor base current; a variable resistor coupled at one end thereof to the emitter of said third transistor, the voltage across said resistor being a variable reference voltage; circuit means having a first current flowing therein for providing a base current for said second transistor, which second transistor base current is a portion of said first current, the remaining portion of said first current flowing to the collector of said third transistor, a change in the motor voltage applied to said motor relative to said variable reference voltage causing a corresponding change in the base current of said third transistor and Consequently the base current and collector current of said second transistor, thereby changing the collector current of said first transistor, and hence the motor voltage applied to said motor; and a fourth transistor, having a fourth transistor collector current when conducting, connected between said power source and said one end of said variable resistance, to the base of which fourth transistor is applied a portion of the collector current of said second transistor, said fourth transistor collector current changing accordingly as the load on said motor changes, with a resulting change in said variable reference voltage, thereby resulting in a change in the rotational speed of said motor.
Claim 3
Dependent Claim
143 words
A circuit for controlling the rotational speed of a micromotor which micromotor is responsive to a motor voltage applied to its terminals, comprising: current passage means coupled to one terminal of a two-terminal source of direct voltage and operative to provide said micromotor with a variable current; means including a variable resistance, for establishing an automatically variable reference voltage; means for detecting the motor voltage applied to said micromotor; means for comparing said detected voltage with said variable reference voltage; first control means responsive to the magnitude of said variable current and connected to said comparing means for automatically controlling said variable reference voltage; and second control means responsive to said comparing means for controlling said current passage means to provide said variable current and the motor voltage to said micromotor such that the speed of said micromotor remains constant under varying loads.
Claim 4
Dependent Claim
143 words
A circuit for controlling the rotational speed of a micromotor which micromotor is responsive to a motor voltage applied to its terminals, comprising: current passage means coupled to one terminal of a two-terminal source of direct voltage and operative to provide said micromotor with a variable current; means including a variable resistance, for establishing an automatically variable reference voltage; means for detecting the motor voltage applied to said micromotor; means for comparing said detected voltage with said variable reference voltage; first control means responsive to the magnitude of said variable current and connected to said comparing means for automatically controlling said variable reference voltage; and second control means responsive to said comparing means for controlling said current passage means to provide said variable current and the motor voltage to said micromotor such that the speed of said micromotor remains constant under varying loads.
Claim 5
Dependent Claim
73 words
A circuit according to claim 2, wherein said first control means comprises a first transistor the emitter-collector circuit of said first transistor being connected between said one terminal of said source of direct voltage and one end of said variable resistance, the other end of said variable resistance being coupled to the other terminal of said source of direct voltage, the base of said first transistor being connected to said second control means.
Claim 6
Dependent Claim
29 words
A circuit according to claim 3, wherein the base of said first transistor is coupled to said one terminal of said source of direct voltage through a given resistance.
Claim 7
Dependent Claim
64 words
A circuit according to claim 4, wherein said comparing means is a second transistor, the collector of said second transistor being coupled to said second control means and said one terminal of said voltage source, the emitter of said second transistor being coupled to said one side of said variable resistance and the base of said second transistor being coupled to said detecting means.
Claim 8
Dependent Claim
70 words
A circuit in accordance with claim 5, wherein said second control means is a third transistor, the collector of said third transistor being coupled to said one terminal of said source of direct voltage, and the base of said first transistor, the emitter of said third transistor being coupled to said current passage means, and the base of said third transistor being coupled to said collector of said second transistor.
References Cited (Backward Citations)
US3309596A
Cited
US3348112A
Cited
US3440511A
Cited
US3422331A
Cited
US3566229A
Cited
US3617846A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-09-23 | 1978-03-25 | 1978-09-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-09-23 | 1982-03-25 | 1982-09-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-09-23 | 1986-03-25 | 1986-09-24 | $7700.00 | Window Closed / Lapsed |