Force sensor with strain relief
First Claim
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1. A force sensor for detecting a force of a touch on a display surface of a device, the force sensor comprising:
- a first force-sensitive film and a second force-sensitive film, separated by at least one adhesive layer, each force-sensitive film having;
polymer chains substantially aligned in a primary direction in a plane of the respective force-sensitive film such that a strain in the primary direction results in a substantially reduced net charge; and
an array of slit features formed into the respective force-sensitive film and oriented in a first direction that is approximately 45 degrees to the primary direction;
wherein;
the array of slit features relieve strain in the respective force-sensitive film allowing the respective force-sensitive film to deflect in a second direction approximately 90 degrees to the first direction;
wherein;
the primary direction of the first force-sensitive film is different from the primary direction of the second force-sensitive film; and
the first and second force-sensitive films are transparent.
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Abstract
A transparent force sensor for detecting an applied force on a surface of a device. The transparent force sensor includes a transparent force-sensitive film having an array of strain-relief features oriented along a first direction. The transparent force-sensitive film is formed from a transparent piezoelectric material that exhibits a substantially reduced net charge when strained along a primary direction. The force sensor also includes a display element disposed on one side of the transparent force-sensitive film.
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Citations
20 Claims
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1. A force sensor for detecting a force of a touch on a display surface of a device, the force sensor comprising:
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a first force-sensitive film and a second force-sensitive film, separated by at least one adhesive layer, each force-sensitive film having; polymer chains substantially aligned in a primary direction in a plane of the respective force-sensitive film such that a strain in the primary direction results in a substantially reduced net charge; and an array of slit features formed into the respective force-sensitive film and oriented in a first direction that is approximately 45 degrees to the primary direction;
wherein;the array of slit features relieve strain in the respective force-sensitive film allowing the respective force-sensitive film to deflect in a second direction approximately 90 degrees to the first direction;
wherein;the primary direction of the first force-sensitive film is different from the primary direction of the second force-sensitive film; and the first and second force-sensitive films are transparent. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A force sensor for detecting a force applied to a display surface of a device, the force sensor comprising:
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a cover forming a portion of an exterior surface of the device; a first transparent force-sensitive film and a second transparent force-sensitive film with anisotropic strain properties disposed in a stack below the cover and each transparent force-sensitive film having; a primary direction oriented in a plane of the respective transparent force-sensitive film for which a strain in the primary direction results in a substantially reduced net charge; an array of strain-relief features formed into the respective transparent force-sensitive film and oriented in a first direction that is transverse to the primary direction thereby allowing the respective transparent force-sensitive film to deflect in a direction approximately perpendicular to the first direction; and a display element disposed below the stack of transparent force-sensitive films;
wherein;the primary direction of the first transparent force-sensitive film is different from the primary direction of the second transparent force-sensitive film. - View Dependent Claims (9, 10, 11, 12, 13)
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14. A force sensor for detecting a force of a touch on a display of a device, the force sensor comprising:
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a first transparent force-sensitive film having; polymer chains oriented in a first primary direction in a plane of the first transparent force-sensitive film, such that a strain in the first primary direction results in a substantially reduced net charge; an array of strain-relief features formed into the first transparent force-sensitive film and oriented in a first direction that is transverse to the first primary direction; and a second transparent force-sensitive film, separated from the first transparent force-sensitive film by an adhesive layer and having; polymer chains oriented in a second primary direction in a plane of the second transparent force-sensitive film, such that a strain in the second primary direction results in a substantially reduced net charge; and an array of strain-relief features formed into the second transparent force-sensitive film oriented in a second direction that is transverse to the second primary direction;
whereineach of the first and the second transparent force-sensitive films are formed from a material that exhibits a strain-direction dependent charge polarity; the first direction is substantially perpendicular to the second direction; and the first primary direction is different from the second primary direction. - View Dependent Claims (15, 16, 17, 18, 19, 20)
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Specification