US 12,130,986 B2
Capacitance detection device and input device
Akihisa Iikura, Miyagi-ken (JP); and Tomoya Sasaki, Miyagi-ken (JP)
Assigned to Alps Alpine Co., Ltd., Tokyo (JP)
Filed by Alps Alpine Co., Ltd., Tokyo (JP)
Filed on Nov. 3, 2022, as Appl. No. 17/980,332.
Application 17/980,332 is a continuation of application No. PCT/JP2021/015293, filed on Apr. 13, 2021.
Claims priority of application No. 2020-081806 (JP), filed on May 7, 2020.
Prior Publication US 2023/0058404 A1, Feb. 23, 2023
Int. Cl. G06F 3/041 (2006.01); G01D 5/24 (2006.01); G06F 3/044 (2006.01)
CPC G06F 3/0418 (2013.01) [G01D 5/24 (2013.01); G06F 3/044 (2013.01); G06F 2203/04107 (2013.01)] 11 Claims
OG exemplary drawing
 
1. A capacitance detection device for detecting a capacitance between an object and a detection electrode, the device comprising:
a first node connected to the detection electrode;
a first capacitor disposed in a path between the first node and a second node;
a second capacitor disposed in a path between the first node and ground;
a third node connected to a shield electrode placed in proximity to the detection electrode;
a third capacitor disposed in a path between the first node and the third node;
an alternating-current voltage output circuit configured to output a first alternating-current voltage to the third node;
a first attenuation circuit connected to the third node and configured to output a second alternating-current voltage by attenuating an amplitude of the first alternating-current voltage; and
a charge amplifier connected to the first attenuation circuit and configured to supply an electric charge to the first capacitor through the second node such that a voltage generated at the second node approaches the second alternating-current voltage, the charge amplifier outputting a detection signal corresponding to the electric charge supplied to the first capacitor.