Various devices and systems such as computing devices (e.g., notebook computers, tablets, personal digital assistants, smartwatches, mapping devices, audio players), mobile communication devices (e.g., smartphones, cellphones), automotive equipment (e.g., cars, trucks, motorcycles), industrial equipment (e.g., machinery, tools), home white goods (e.g., appliances, security systems), and entry systems (e.g., home entry, automotive entry, secure area entry) may require an authentication method to protect against unauthorized access. Fingerprint authentication using fingerprint sensors may protect an apparatus or system against unauthorized access.
Fingerprint sensors may use various capacitive sensing methods to image a fingerprint pattern, where imaging a fingerprint means detecting a fingerprint and generating a set of data values, or “fingerprint data,” that represents the fingerprint in digital format. The fingerprint data may be an image or other information specific to a fingerprint. This method requires direct contact or close proximity of the portion of the finger comprising the fingerprint, or “finger pad,” with the sensor surface. A very thin cover, or overlay, may be disposed over the sensor surface. Overlays may typically be less than 150 μm in thickness. Thick covers or overlays between the fingerprint and the fingerprint sensor may obscure fingerprint features.
There may be a variety of situations when a user wearing a glove or other hand enclosure may want to image a fingerprint. A glove may protect the hand against harmful environmental factors, such as cold and water, and harmful physical factors, such as sharp objects and corrosive chemicals. A glove may be fabricated using material such as, but not limited to, fabric, latex, or rubber. Current fingerprint sensors cannot image fingerprints through glove materials. Using glove materials that are thin enough to enable fingerprint sensing may limit the protective effectiveness of the materials. If using thick glove materials, the user may have to remove the glove to image a fingerprint, which may be inconvenient and/or dangerous. It is desirable to create a glove or other hand enclosure using materials that are thick enough for protection but enable a fingerprint sensor to accurately image a fingerprint.
Similarly, devices with fingerprint sensors are often enclosed in a protective enclosure, or the front face of the device is covered by a protective cover. A protective enclosure or cover protects the device and/or sensor against harmful environmental factors, such as cold and water, and harmful physical factors, such as sharp objects and corrosive chemicals. A protective enclosure or cover may be fabricated with rigid material, such as, but not limited to, glass or plastic, or flexible material, such as, but not limited to, fabric or film. A protective enclosure may completely enclose a device or may partially enclose a device. Current fingerprint sensors cannot image fingerprints through thick material. Using an enclosure or cover material that is thin enough to enable fingerprint sensing may limit the protective effectiveness of the enclosure or film. If using a thick enclosure or cover material, the user may have to remove the device from the enclosure or cover to enable fingerprint sensing. Removing the cover or enclosure may be inconvenient for the user and and/or may risk damaging the device. It is desirable to create a protective enclosure or cover made of material that is thick enough for protection but enables a fingerprint sensor to accurately image a fingerprint.