US 11,942,285 B2
Strain sensing key membrane
Chia Chi Wu, Taipei (TW); Michael Vosgueritchian, San Francisco, CA (US); Ming Gao, Shanghai (CN); Nan Chen, Shanghai (CN); Vyom Sharma, Portland, OR (US); and Wenhao Wang, Shanghai (CN)
Assigned to APPLE INC., Cupertino, CA (US)
Filed by Apple Inc., Cupertino, CA (US)
Filed on Nov. 2, 2022, as Appl. No. 18/051,954.
Application 18/051,954 is a continuation of application No. 16/586,280, filed on Sep. 27, 2019, granted, now 11,501,933.
Prior Publication US 2023/0298834 A1, Sep. 21, 2023
This patent is subject to a terminal disclaimer.
Int. Cl. H01H 13/84 (2006.01); G01L 1/18 (2006.01); G01L 1/22 (2006.01); H01H 13/7065 (2006.01)
CPC H01H 13/84 (2013.01) [G01L 1/18 (2013.01); G01L 1/2287 (2013.01); H01H 13/7065 (2013.01); H01H 2221/002 (2013.01); H01H 2300/03 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A keyboard, comprising:
a base;
a keycap configured to translate relative to the base between a first position, a second position, and a third position; and
a membrane layer positioned between the keycap and the base, the membrane layer including:
a flexible sheet;
a first piezoresistor positioned on the flexible sheet between the keycap and the base and having a variable first resistance;
a second piezoresistor positioned on the flexible sheet between the keycap and the base and having a variable second resistance; and
a conductor connecting the first piezoresistor to the second piezoresistor;
wherein, in response to movement of the keycap between the first position and the second position, a voltage measured at the conductor, and influenced by a ratio of the variable first resistance and the variable second resistance, is less than a predetermined threshold value; and
wherein, in response to movement of the keycap between the second position and the third position, the voltage measured at the conductor, and influenced by the ratio of the variable first resistance to the variable second resistance, is greater than the predetermined threshold value due to deformation of at least the first piezoresistor.