Temperature indicator
First Claim
1. A temperature indicating device comprising:
- a bimetallic element which is normally curved in a first direction, reverses its direction of curvature to a second direction of curvature when heated to a temperature above a predetermined upper threshold and returns to its normal first direction of curvature when it cools to a temperature below a predetermined lower threshold;
a housing having an internal recess within which said bimetallic element rests when in its first direction of curvature; and
a spring which exerts a force on said bimetallic element and which holds the bimetallic element securely in said internal recess when said bimetallic element has said first direction of curvature and which ejects said bimetallic element from said recess when said bimetallic element changes to said second direction of curvature.
1 Assignment
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Accused Products
Abstract
A low cost device which changes rapidly, significantly, irreversibly, and accurately when it is exposed to a predetermined temperature is disclosed. The device of the present invention employs a bimetallic disk which changes its configuration when it is exposed to a predetermined temperature. Before firing, the disk is captured by a recess in the device casing. When the disk is exposed to a predetermined temperature, it changes configuration and escapes its confinement from its orginal location in the recess. A spring propels the disk from its original location to a different location. Additionally, the spring ensures that the disk cannot return to its original location. This device has a minimal number of parts so that it is easily and inexpensively manufactured. It can be configured to sense either high temperature or low temperature. The low temperature device can be used in conjuction with irreversible temperature labels such that the combination records both a high and a low temperature exposure. Additionally, the device can be locked such that it does not register exposure to a predetermined temperature until the device is activated for use.
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Citations
33 Claims
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1. A temperature indicating device comprising:
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a bimetallic element which is normally curved in a first direction, reverses its direction of curvature to a second direction of curvature when heated to a temperature above a predetermined upper threshold and returns to its normal first direction of curvature when it cools to a temperature below a predetermined lower threshold; a housing having an internal recess within which said bimetallic element rests when in its first direction of curvature; and a spring which exerts a force on said bimetallic element and which holds the bimetallic element securely in said internal recess when said bimetallic element has said first direction of curvature and which ejects said bimetallic element from said recess when said bimetallic element changes to said second direction of curvature. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A temperature indicating device comprising:
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a housing, said housing having a top casing and a bottom casing; said bottom casing having an upper and lower surface, said bottom casing having a channel with a longitudinal axis, said channel leading into a circular recess, said circular recess having upstanding walls;
a bimetallic disk, having a forward portion and a rear portion, stressed such that it becomes convex when observed from said bottom casing, said disk configured to rest in said recess in an un-activated state, said disk being capable of inverting such that said convex surface becomes concave when said disk is activated by being exposed to a predetermined temperature;said top casing having an upper and lower surface, said top casing additionally having a viewing window located such that said disk cannot be seen in said viewing window when said device is un-activated and said disk can be seen in said viewing window when said device is activated; a spring which, when said device is in said unactivated state, contacts an edge of said bimetallic disk, thereby securing said disk against said recess wall; at least one forward leg located above said circular recess, protruding from a lower surface of said top casing, said one forward leg preventing said disk from exiting said circular recess before said disk inverts at said predetermined temperature; at least one rear leg protruding from said lower surface of said top casing, located in close proximity to said rear portion of said disk such that said rear leg and an upper portion of said bottom casing provide a slip fit retainer for said rear portion of said disk; and a locking tab having a handle and an extension, said extension entering said casing through a notch in said casing, said extension acting to ensure that said device can not activate prematurely.
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18. A temperature indicating device comprising:
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a bimetallic element which is normally curved in a first direction, reverses its direction of curvature to a second direction of curvature when heated to a temperature above a predetermined upper threshold and returns to its normal first direction of curvature when it cools to a temperature below a predetermined lower threshold; a housing having an internal recess within which said bimetallic element rests when in its first direction of curvature; and a biasing member having a first state which exerts a force on said bimetallic element and which holds said bimetallic element in said internal recess when said bimetallic element has said first direction of curvature. - View Dependent Claims (19, 20)
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21. A temperature indicating device comprising:
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a bimetallic element which is normally curved in a first direction, reverses its direction of curvature to a second direction of curvature when heated to a temperature above a predetermined upper threshold and returns to its normal first direction of curvature when it cools to a temperature below a predetermined lower threshold; a housing having a window; a spring which exerts a force on said bimetallic element, said spring having an semaphore which is visible through said window only when said bimetallic element has said second direction of curvature. - View Dependent Claims (22, 23, 24, 25)
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26. A temperature indicating device comprising:
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a housing having a window; a donut shaped bimetallic element defining a central hole, said element being normally curved in a first direction which changes to a second direction of curvature when heated to a temperature above a predetermined upper threshold temperature; a semaphore which is insertable in said hole of said bimetallic element and is held in a position by said element such that it is visible in said window when said bimetallic element has said first direction of curvature; and a spring which exerts a force on said semaphore, such that when said bimetallic element changes to said second direction of curvature, said semaphore is released from said hole and said spring force moves said semaphore to a position within said housing where said semaphore is not visible through said window and said spring holds said semaphore in said position. - View Dependent Claims (27, 28)
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29. A temperature indicating device comprising:
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a bimetallic element which is normally curved in a first direction, reverses its direction of curvature to a second direction of curvature when heated to a temperature above a predetermined upper threshold and returns to its normal first direction of curvature when it cools to a temperature below a predetermined lower threshold; a housing having an internal recess within which said bimetallic element rests when in its first direction of curvature; and a spring which exerts a force on said bimetallic element which holds said bimetallic element securely in said internal recess when said bimetallic element has said first direction of curvature.
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30. A temperature indicating device comprising:
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a bimetallic element which is normally curved in a first direction, reverses its direction of curvatures to a second direction of curvature when cooled to a temperature below a predetermined lower threshold and returns to its normal first direction of curvature when heated to a temperature above a predetermined upper threshold; a housing having an internal recess within which said bimetallic element rests when in its first direction of curvature; and a spring which exerts a force on said bimetallic element to hold said bimetallic element securely in said internal recess when said bimetallic element has said first direction curvature. - View Dependent Claims (31)
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32. A temperature indicating device comprising:
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a bimetallic element which is normally curved in a first direction, reverses its direction of curvature to a second direction of curvature when heated to a temperature above a predetermined upper threshold and returns to its normal first direction of curvature when it cools to a temperature below a predetermined lower threshold; a housing having an internal recess within which said bimetallic element rests when in its first direction of curvature; and a resilient biasing member which exerts a force on said bimetallic element which holds said bimetallic element securely in said internal recess when said bimetallic element has said first direction of curvature.
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33. A temperature indicating device comprising:
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a bimetallic element which is normally curved in a first direction, reverses its direction of curvature to a second direction of curvature when cooled to a temperature below a predetermine lower threshold and returns to its normal first direction of curvature when heated to a temperature above a predetermined upper threshold; a housing having an internal recess within which said bimetallic element rests when in its first direction of curvature; and a resilient biasing member which exerts a force on said bimetallic element to hold said bimetallic element securely in said internal recess when said bimetallic element has said first direction curvature.
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Specification