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US 5,493,078 AGranted
Electronic balance and its application to a thermal analyzer
AssigneeShimadzu Corporation
InventorMitsumasa Uchiike
Life of this patent
Estimating the term…
Abstract
An electronic balance provided with a correcting circuit for canceling a thermal drift in the output of a photoreceiver. The photoreceiver is composed of two photosensitive areas and the shadow of a shutter moving with the beam of the balance is cast on the two photosensitive areas. The outputs of the two photosensitive areas are sent to a first subtracting circuit and an adding circuit. The output of the first subtracting circuit is corrected by the output of the adding circuit to produce signal independent of temperature change and corresponding only to the turn of the beam of the electronic balance.
Claims12
An electronic balance comprising:
- a beam sustained by a fulcrum and supporting a sample at a first arm of the beam;
- an electromagnetic device for electromagnetically exerting a force on the beam;
- a shutter fixed to the beam;
- a photoemitter;
- a photoreceiver placed opposing the photoemitter and including a first photosensitive area and a
- second photosensitive area aligned along a movement direction of the shutter so that a shadow of the shutter is cast on a portion of each of the first and second photosensitive areas;
- a controller for receiving a first output and a second output from the first and second photosensitive areas, respectively and for sending a control signal to the electromagnetic device so that a difference between the first and second outputs is constant at a temperature, the control signal representing a mass of the sample;
- and
- correcting means responsive to the first and second outputs of the first and second photosensitive areas for correcting variations in the difference between the first and second outputs based on a sum of the first and second outputs, the variations resulting from changes in the temperature.
6 more elements
An electronic balance comprising:
- a beam sustained by a fulcrum and supporting a sample at a first arm of the beam;
- an electromagnetic device for electromagnetically exerting a force on the beam;
- a shutter fixed to the beam;
- a photoemitter;
- a photoreceiver placed opposing the photoemitter and including a first photosensitive area, a second photosensitive area, and a third photosensitive area in which the first and second photosensitive areas are aligned along a movement direction of the shutter so that a shadow of the shutter is cast on a portion of each of the first and second photosensitive areas and the third photosensitive area is placed out of the shadow;
- a controller for receiving a first output and a second output from the first and second photosensitive areas, respectively and for sending a control signal to the electromagnetic device so that a difference between the first and second outputs is constant at a temperature, the control signal representing a mass of the sample;
- and
- correcting means responsive to an output of the third photosensitive area for correcting the control signal to compensate for variations in the difference between the first and second outputs resulting from changes in the temperature, based on the output of the third photosensitive area.
5 more elements
A thermal analyzer comprising:
- a beam sustained by a fulcrum and supporting a sample at a first arm of the beam;
- at least one of a heater and a cooler placed around the sample;
- an electromagnetic device for electromagnetically exerting a force on the beam;
- a shutter fixed to the beam;
- a photoemitter;
- a photoreceiver placed opposing the photoemitter and including a first photosensitive area and a second photosensitive area aligned along a movement of the shutter so that a shadow of the shutter is cast on a portion of each of the first and second photosensitive areas;
- a controller for controlling the at least one of a heater and a cooler, for receiving a first output and a second output from the first and second photosensitive areas, respectively and for sending a control signal to the electromagnetic device so that a difference between the first and second outputs is constant at a temperature, the control signal representing a mass of the sample;
- and
- correcting means responsive to the first and second outputs of the first and second photosensitive areas for correcting the control signal to compensate for variations in the difference between the first and second outputs resulting from changes in the temperature, based on a sum of the first and second outputs.
6 more elements
A thermal analyzer comprising:
- a beam sustained by a fulcrum and supporting a sample at a first arm of the beam;
- at least one of a heater and a cooler placed around the sample;
- an electromagnetic device for electromagnetically exerting a force on the beam;
- a shutter fixed to the beam;
- a photoemitter;
- a photoreceiver placed opposing the photoemitter and including a first photosensitive area, a second photosensitive area, and a third photosensitive area in which the first and second photosensitive areas are aligned along a movement direction of the shutter so that a shadow of the shutter is cast on a portion of each of the first and second photosensitive areas and the third photosensitive area is placed out of the shadow;
- a controller for controlling the at least one of a heater and a cooler, for receiving a first output and a second output from the first and second photosensitive areas, respectively and for sending a control signal to the electromagnetic device so that a difference between the first and second outputs is constant at a temperature, the control signal representing a mass of the sample;
- and
- correcting means responsive to an output of the third photosensitive area for correcting the control signal to compensate for variations in the difference between the first and second outputs resulting from changes in the temperature, based on the output of the third photosensitive area.
6 more elements
Dependencies are inferred from the claim text.