Cambridge Touch Technologies Ltd.

Mojtaba Bagheri

Babak Bastani

Michael Robert Astley

Xiang Cheng

Jiahao Li

A device for touch panel pressure detection includes a plurality of first input/output terminals for a projected capacitance touch panel. The projected capacitance touch panel includes a layer of piezoelectric material disposed between a plurality of sensing electrodes and a common electrode. The device also includes one or more amplifiers. Each amplifier has an inverting input, a non-inverting input and an output. The non-inverting input of the or each amplifier is configured to be switched between a common mode voltage and a capacitance measurement signal. The inverting input of the or each amplifier is configured to drive an input/output terminal based on the capacitance measurement signal. The amplifier is configured such that, when an input/output terminal is connected to a sensing electrode, the amplifier output varies in dependence upon a pressure applied to the touch panel.

Touch panel pressure detection

A device () for processing signals from a projected capacitance touch panel () is described. The projected capacitance touch panel () includes a layer of piezoelectric material () disposed between a number of sensing electrodes () and at least one counter electrode (). The device () includes a capacitive touch controller () having a number of measurement ports (). The device () also includes a number of charge amplifiers (). The device () also includes a number of terminals (C, . . . , C, D, . . . , D) for connection to the sensing electrodes () of the projected capacitance touch panel (). Each terminal (C, . . . , C, D, . . . , D) is connected to one of the measurement ports (). Each terminal (C, . . . , C, D, . . . , D) is also connected to an input of one of the charge amplifiers () via a corresponding switch (SW) of a number of switches (). The device () also includes a controller () configured to synchronise the capacitive touch controller () and the number of switches (SW,) so that during a first portion ([t, t]) of a cycle the capacitive touch controller () outputs a capacitance measurement signal () to one or more of the terminals (C, . . . , C, D, . . . , D), and the plurality of charge amplifiers () are disconnected from the terminals (C, . . . , C, D, . . . , D) by the respective switches (SW,). The controller () is also configured to synchronise the capacitive touch controller () and the number of switches (SW,) so that during a second portion ([t, t]) of the cycle the capacitive touch controller () does not output the capacitance measurement signal (), and one or more of the charge amplifiers () are connected to the corresponding terminals (C, . . . , C, D, . . . , D) by the respective switches (SW,).

Device for processing signals from a pressure-sensing touch panel

A device () is provided for processing signals () from a projected capacitance touch panel (), the touch panel () including a layer of piezoelectric material () disposed between a plurality of first electrodes () and at least one second electrode (). The device is configured, in response to receiving input signals () from a given first electrode (), to generate a pressure signal () indicative of a pressure applied to the touch panel () proximate to the given first electrode () and a capacitance signal () indicative of a capacitance of the given first electrode (). The device () includes an amplifier () configured to generate an amplified signal () based on the input signals (). The device () also includes an analog-to-digital converter () configured to be synchronised () with the capacitance signal (), and to generate the pressure signal () by sampling the amplified signal () at times corresponding to the amplitude of the capacitance signal () being substantially equal to a ground, common mode or minimum value.

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Cambridge, United Kingdom

Mojtaba Bagheri