Fingerprint sensors using membrane switch arrays
First Claim
1. A method of making an integrated texture sensor for sensing a texture that is protected from external contaminating particulates and will self-equalize using air from outside the sensor, comprising:
- a) forming a plurality of conductive row lines and a plurality of conductive column lines on a substrate, each of the row lines being insulated from each other and each of the column lines being insulated from each other, the row lines and column lines intersecting to form a switch area between adjacent row lines and adjacent column lines;
b) forming a lower electrode in each of a plurality of switch areas;
c) forming a sacrificial area directly over each lower electrode and a non-sacrificial area around each sacrificial area;
d) forming an individual membrane above each sacrificial area, the individual membrane being anchored to the non-sacrificial area, the individual membrane comprising an upper electrode disposed directly above the sacrificial area, wherein the individual membrane does not cover a channel area adjacent to the sacrificial area and is separate from individual membranes formed above other sacrificial areas;
e) removing each sacrificial area by introducing a sacrificial etchant through the channel area, thereby forming a cavity region at each sacrificial area; and
f) sealing the channel area adjacent to each sacrificial area by forming a vent seal having a thickness selected to close each cavity region from the external contaminating particulates while permitting self-equalization of air pressure within the each cavity region with air that is external to the sensor.
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Accused Products
Abstract
A method of making an integrated texture sensor for sensing a texture is described. In one embodiment, the method is directed to a sensor that that is protected from external contaminating particulates and will self-equalize using air from outside the sensor. Further combinations of such protection among various membrane switches, in combination with various types of membranes, is described. In another embodiment, a method of making a skin-texture sensor for sensing a skin texture having a plurality of ridges and a plurality of valleys is described, such that when completed, applying a ridge of the texture to a membrane switch will cause flexure of the membrane resulting in a contact between the lower electrode and the upper electrode, the contact establishing an electrical communication between said one of the row lines and said one of the column lines, whereas disposing a valley of the texture over said each membrane switch will not result in the contact between the lower electrode and the upper electrode.
61 Citations
25 Claims
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1. A method of making an integrated texture sensor for sensing a texture that is protected from external contaminating particulates and will self-equalize using air from outside the sensor, comprising:
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a) forming a plurality of conductive row lines and a plurality of conductive column lines on a substrate, each of the row lines being insulated from each other and each of the column lines being insulated from each other, the row lines and column lines intersecting to form a switch area between adjacent row lines and adjacent column lines; b) forming a lower electrode in each of a plurality of switch areas; c) forming a sacrificial area directly over each lower electrode and a non-sacrificial area around each sacrificial area; d) forming an individual membrane above each sacrificial area, the individual membrane being anchored to the non-sacrificial area, the individual membrane comprising an upper electrode disposed directly above the sacrificial area, wherein the individual membrane does not cover a channel area adjacent to the sacrificial area and is separate from individual membranes formed above other sacrificial areas; e) removing each sacrificial area by introducing a sacrificial etchant through the channel area, thereby forming a cavity region at each sacrificial area; and f) sealing the channel area adjacent to each sacrificial area by forming a vent seal having a thickness selected to close each cavity region from the external contaminating particulates while permitting self-equalization of air pressure within the each cavity region with air that is external to the sensor. - View Dependent Claims (2, 3, 4, 5, 6, 12, 13, 14, 15, 24, 25)
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7. A method of making a skin-texture sensor for sensing a skin texture having a plurality of ridges and a plurality of valleys, comprising:
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a) establishing a base; b) disposing a plurality of conductive row lines on the base; c) disposing a plurality of conductive column lines on the base, the column lines being insulated from the row lines; and d) forming an array of membrane switches on the base such that a spacing between adjacent switches in the array is less than one half of a spacing between adjacent ridges, each membrane switch corresponding to a pair of one of the row lines and one of the column lines, wherein forming each membrane switch of the array comprises; disposing a lower electrode on the base, electrically connecting the lower electrode to said one of the row lines, disposing a flexible upper membrane structure over the lower electrode, comprising an upper electrode disposed facing the lower electrode separated from the lower electrode by a cavity and connected to said one of the column lines, the flexible upper membrane structure being separate from the flexible upper membrane structures of the other membrane switches in the array, wherein applying a ridge of the texture to said each membrane switch causes a flexure of the membrane resulting in a contact between the lower electrode and the upper electrode, the contact establishing an electrical communication between said one of the row lines and said one of the column lines, and wherein disposing a valley of the texture over said each membrane switch does not result in the contact between the lower electrode and the upper electrode. - View Dependent Claims (8, 9, 10, 11, 16, 17, 18, 19, 20, 21, 22, 23)
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Specification