Capacitance measurement circuit module

Patent metadata

Field	Value
Publication number	US-2024302924-A1
Application number	US-202418586202-A
Country	US
Kind code	A1
Filing date	Feb 23, 2024
Priority date	Mar 6, 2023
Publication date	Sep 12, 2024
Grant date	—

Abstract

A capacitance measurement circuit module has: a sensor electrode, for input detection, disposed on a wiring board; a sensor-side shield electrode shielding the sensor electrode; board-side measurement terminals connected to the sensor electrode; a board-side shield terminal connected to the sensor-side shield electrode; a measurement integrated circuit having circuit-side measurement terminals connected to the board-side measurement terminals and a circuit-side shield terminal connected to the board-side shield terminal, the circuit outputting measurement signals from the circuit-side measurement terminals and outputting, from the circuit-side shield terminal, a shield signal having the same frequency and phase as the measurement signals, the circuit being disposed on the wiring board and measuring capacitance of the sensor electrode; and a circuit-side shield electrode that is positioned on the wiring board so as to face the measurement integrated circuit and to be adjacent to the board-side measurement terminals and is connected to the board-side shield terminal.

First claim

1 . A circuit module for measuring capacitance, comprising:
a wiring board having a first surface and a second surface opposite to the first surface; a sensor electrode disposed on the first surface of the wiring board and configured to detect a change in capacitance; a sensor-side shield electrode disposed on the first surface and configured to shield the sensor electrode; at least one board-side measurement terminal disposed on the second surface and connected to the sensor electrode via the wiring board; a board-side shield terminal disposed on the second surface and connected to the sensor-side shield electrode via the wiring board; a circuit-side shield electrode disposed on the second surface, adjacent to the board-side measurement terminal, and connected to the board-side shield terminal; and a measurement integrated circuit (IC) provided on the second surface so as to overlap a portion of the circuit-side shield electrode in plan view from a direction normal to the second surface, the measurement IC including:
at least one circuit-side measurement terminal connected to the at least one board-side measurement terminal; and
a circuit-side shield terminal connected to the board-side shield terminal,
wherein the measurement IC is configured to measure capacitance of the sensor electrode, by outputting a measurement signal from the at least one circuit-side measurement terminal and a shield signal from the circuit-side shield terminal, the shield signal having a frequency and a phase which are the same as that of the measurement signal.

2 . The circuit module according to claim 1 , further comprising:
a ground electrode disposed on the second surface of the wiring board and adjacent to the circuit-side shield electrode, wherein the measurement IC further includes:
a plurality of circuit-side ground terminals connected to the ground electrode; and
a plurality of circuit-side measurement terminals, each of which is positioned adjacent to another of the plurality of circuit-side measurement terminals or one of the plurality of circuit-side ground terminals.

3 . The circuit module according to claim 2 ,
wherein the measurement IC is in a rectangular shape in the plan view and having four sides in plan view which are a control side and three measurement sides, wherein the measurement IC further includes:
a power supply terminal disposed on the control side and connected to a power supply;
an output terminal disposed on the control side, from which a signal representing a capacitance value is output; and
a control terminal disposed on the control side, to and from which a digital signal is input or output,
wherein the plurality of circuit-side measurement terminals, the circuit-side shield terminal, and some of the plurality of circuit-side ground terminals are disposed on the three measurement sides, and at least one of the plurality of circuit-side ground terminals is disposed on the controls side, and wherein the ground electrode includes a first ground electrode portion extending along the control side and overlapping the measurement IC in the plan view.

4 . The circuit module according to claim 3 ,
wherein the plurality of circuit-side measurement terminals are divided into four circuit-side terminal groups and arranged on the three measurement sides of the measurement IC, such that a first circuit-side terminal group is disposed on a first measurement side, a second circuit-side terminal group is disposed on the first measurement side and a second measurement side adjacent to the first measurement side, a third circuit-side terminal group is disposed on the second measurement side and a third measurement side adjacent to the second measurement side, and a fourth circuit-side terminal group is disposed on the third measurement side, the control side being opposite to the second measurement side and adjacent to the first and third measurement side, wherein the measurement IC is further configured to output the measurement signal from the plurality of circuit-side measurement terminals group by group such that the four circuit-side terminal groups output the measurement signal at different times, while the circuit-side measurement terminals in a same group output the measurement signal at a same time, wherein the circuit-side shield terminal is disposed at an end of the first measurement side adjacent to the control side, and the plurality circuit-side ground terminals are disposed between the first circuit-side terminal group and the second circuit-side terminal group on the first measurement side, between the second circuit-side terminal group and the third circuit-side terminal group on the second measurement side, and between the third circuit-side terminal group and the fourth circuit-side terminal group on the third measurement side, wherein the ground electrode further includes:
a second ground electrode portion extending from the first ground electrode portion in parallel to and between the first measurement side and the third measurement side toward the second measurement side, and connected to the circuit-side ground terminal disposed between the second circuit-side terminal group and the third circuit-side terminal group on the second measurement side;
a third ground electrode portion extending from the second ground electrode portion in parallel to and between the control side and the second measurement side toward the first measurement side and connected to the circuit-side ground terminal disposed between the first circuit-side terminal group and the second circuit-side terminal group on the first measurement side; and
a fourth ground electrode portion extending from the second ground electrode portion in parallel to and between the control side and the second measurement side toward the third measurement side and connected to the circuit-side ground terminal disposed between the third circuit-side terminal group and the fourth circuit-side terminal group on the third measurement side,
and wherein the circuit-side shield electrode is disposed to have a predetermined spacing from the first ground electrode portion, the second ground electrode portion the third ground electrode portion, and the fourth ground electrode portion, respectively, in the plan view.

5 . The circuit module according to claim 4 ,
wherein the board-side measurement terminals are divided into four board-side terminal groups and arranged correspondingly to the four circuit-side terminal groups, wherein the circuit-side shield electrode includes:
a first shield portion disposed in a space between the first ground electrode portion and third ground electrode portion along the second ground electrode portion and arranged for a first board-side terminal group corresponding to the first circuit-side terminal group on the first measurement side;
a second shield portion disposed in a corner space between the second ground electrode portion and the third ground electrode portion and arranged for a second board-side terminal group corresponding to the second circuit-side terminal group on the first and second measurement sides;
a third shield portion disposed in a corner space between the second ground electrode portion and the fourth ground electrode portion and arranged for a third board-side terminal group corresponding to the third circuit-side terminal group on the second and third measurement sides; and
a fourth shield portion disposed in a space between the first ground electrode portion and the fourth ground electrode portion along the second ground electrode portion and arranged for a fourth board-side terminal group corresponding to the fourth circuit side terminal group on the third measurement side.

Assignees

• Alps Alpine Co Ltd

Inventors

• Takata Masahiro
• Shigetaka Hiroshi

Classifications

• H03K2217/960765

  Details of shielding arrangements · CPC title

• H03K17/955

  using a capacitive detector · CPC title

• H03K17/962

  Capacitive touch switches · CPC title

• G06F2203/04107

  Shielding in digitiser, i.e. guard or shielding arrangements, mostly for capacitive touchscreens, e.g. driven shields, driven grounds · CPC title

• G06F3/044 Primary

  by capacitive means · CPC title