Electrical generator or motor structure – Non-dynamoelectric – Thermal or pyromagnetic
Reexamination Certificate
2000-01-06
2001-06-05
Waks, Joseph (Department: 2834)
Electrical generator or motor structure
Non-dynamoelectric
Thermal or pyromagnetic
C310S307000, C310S0400MM, C060S527000, C060S528000
Reexamination Certificate
active
06242841
ABSTRACT:
FIELD OF THE INVENTION
The invention relates generally to the field of photography, and in particular to motors for cameras such as used for film winding purposes. More specifically, the invention relates to a stepper motor with a shaped memory alloy rotary-driver.
BACKGROUND OF THE INVENTION
Prior art U.S. Pat. No. 5,279,123 mentions that shaped memory alloy (abbreviated to SMA) devices are well known in the art to undergo a martensitic (diffusionless) transition dependent upon the temperature applied to the SMA device. The SMA device when heated above its transition temperature undergoes a shape change to a memorized shape and when cooled below its transition temperature reverses the shape change from the memorized shape to an original shape. This change in shape can be used to provide mechanical work.
Often, as disclosed in prior art U.S. Pat. No. 5,459,544 issued Oct. 17, 1995, the SMA device is a metallic wire. When electrical current is applied to lead wires connected to opposite ends of the SMA wire, the SMA wire is heated to due to electrical resistance and it shrinks or contacts, i.e. recovers, to a memorized shape. When the electrical current is cut, the SMA wire cools to extend, i.e. deform, to an original shape.
SUMMARY OF THE INVENTION
According to one aspect of the invention, a stepper motor comprises:
a rotatable hub;
a first shaped memory alloy (abbreviated to SMA) rotary-driver, which when heated undergoes a shape change to rotationally couple with the hub and rotate the hub in a predetermined direction, and which can be deformed to reverse the shape change to rotationally uncouple from the hub;
a first return spring connected with the first SMA rotary-driver for deforming the first SMA rotary-driver, when no longer heated, to reverse the shape change of the first SMA rotary-driver and rotationally uncouple the first SMA rotary driver from the hub;
a second SMA rotary-driver, which when heated undergoes a shape change to rotationally couple with the hub and rotate the hub in the predetermined direction, and which when can be deformed to reverse the shape change to rotationally uncouple from the hub;
a second return spring connected with the second SMA rotary-driver for deforming the second SMA rotary-driver, when no longer heated, to reverse the shape change of the second SMA rotary-driver and rotationally uncouple the second SMA rotary-driver from the hub; and
a control device for heating the first and second SMA rotary-drivers in succession and only one at a time, whereby the first and second SMA rotary-drivers can take turns to stepwise rotate the hub in the predetermined direction.
According to another aspect of the invention, a method of rotating a film spool in a film winding direction in a camera comprises the steps:
heating a first shaped memory alloy (abbreviated to SMA) rotary-driver to undergo a shape change, which rotationally couples the first SMA rotary-driver with the film spool and rotates the film spool a predetermined angle in the film winding direction;
discontinuing heating the first SMA rotary-driver to allow a first return spring to reverse the shape change of the first SMA rotary-driver, which rotationally uncouples the first SMA rotary-driver from the film spool;
heating a second shaped memory alloy (abbreviated to SMA) rotary-driver to undergo a shape change, which rotationally couples the second SMA rotary-driver with the film spool and rotates the film spool the predetermined angle in the film winding direction, ; and
discontinuing heating the first SMA rotary-driver to allow a first return spring to reverse the shape change of the first SMA rotary-driver, which rotationally uncouples the first SMA rotary-driver from the film spool.
According to another aspect of the invention, a motorized camera comprises:
a main body part including a chamber for a film spool having an engageable end portion;
a driven hub rotatable in a film winding direction, longitudinally extending into the chamber, and configured to coaxially engage the engageable end portion of the film spool in the chamber to rotate the film spool in the film winding direction;
a first drive ring which encircles the hub, is rotatable in the film winding direction to coaxial engage with the hub and rotate the hub in the film winding direction, and is rotatable in a reverse direction to disengage from the hub;
a first shaped memory alloy (abbreviated to SMA) rotary-driver having one end connected to the first drive ring and another end fixed to the main body part, which when heated undergoes a shape change to rotate the first drive ring in the film winding direction, and which can be deformed to reverse the shape change;
a first return spring having one end fixed to the main body part and another end connected with the first drive ring to rotate the first drive ring in the reverse direction to deform the first SMA rotary-driver, when no longer heated, to reverse the shape change of the first SMA rotary-driver;
a second drive ring which encircles the hub, is rotatable in the film winding direction to coaxial engage with the hub and rotate the hub in the film winding direction, and is rotatable in the reverse direction to disengage from the hub;
a second SMA rotary-driver having one end connected to the second drive ring and another end fixed to the main body part, which when heated undergoes a shape change to rotate the second drive ring in the film winding direction, and which can be deformed to reverse the shape change;
a second return spring having one end fixed to the main body part and another end connected with the second drive ring to rotate the second drive ring in the reverse direction to deform the second SMA rotary-driver, when no longer heated, to reverse the shape change of the second SMA rotary-driver; and
a control device for heating the first and second SMA rotary-drivers in succession and only one at a time, whereby the first and second SMA rotary-drivers can take turns to stepwise rotate the hub in the film winding direction.
REFERENCES:
patent: 3280550 (1966-10-01), Cassidy
patent: 4055955 (1977-11-01), Johnson
patent: 4275561 (1981-06-01), Wang
patent: 4434618 (1984-03-01), Dillon
patent: 4761955 (1988-08-01), Bloch
patent: 4785627 (1988-11-01), Al-Jaroudi
patent: 4860040 (1989-08-01), Tamamura et al.
patent: 4899543 (1990-02-01), Romanelli et al.
patent: 4965545 (1990-10-01), Johnson
patent: 4996842 (1991-03-01), Goldstein
patent: 5031711 (1991-07-01), Tanaka et al.
patent: 5086618 (1992-02-01), Tanaka
patent: 5279123 (1994-01-01), Wechsler et al.
patent: 5396769 (1995-03-01), Brudnicki
patent: 5459544 (1995-10-01), Emura
patent: 5955801 (1999-09-01), Romero et al.
patent: 6032549 (2000-03-01), Tokio et al.
patent: 6065934 (2000-05-01), Jacot et al.
patent: 6072639 (2000-06-01), Onda
Eastman Kodak Company
Fields Roger A.
Waks Joseph
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