Capacitive image sensor with noise reduction feature and method operating the same
First Claim
1. A capacitive image sensor, comprising:
- a plurality of capacitive sensing units, arranged in a form of an array, wherein each of the plurality of capacitive sensing units switches between three states;
sensing state, idle state, and emitting state; and
each of the plurality of capacitive sensing units comprises;
a sensing electrode; and
a voltage follower, having an input node connected to the sensing electrode;
a driving source, for providing a driving signal to an adjacent finger overlying the plurality of capacitive sensing units through the plurality of capacitive sensing units which are in the emitting state;
a plurality of driving switches, each connected between one of the plurality of capacitive sensing units and the driving source; and
a control and timing logic, connected to each of the plurality of driving switches, for controlling the state of each of the plurality of capacitive sensing units,wherein an electric potential of the sensing electrode is set to a predetermined voltage and changes in response to the driving signal provided to the adjacent finger while the capacitive sensing unit is in the sensing state;
the electric potential of the sensing electrode is driven by the driving source while the capacitive sensing unit is in the emitting state;
the electric potential of the sensing electrode is set to a constant voltage or left floating while the capacitive sensing unit is in the idle state;
the driving signal has a positive waveform or a negative waveform formed by a potential change or potential changes of the driving source;
the electric potential of each of the plurality of capacitive sensing units is reset before the driving signal is provided to the adjacent finger through the plurality of capacitive sensing units which are in the emitting state.
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Abstract
A capacitive image sensor with noise reduction feature and a method operating the capacitive image sensor are provided. The capacitive image sensor includes: a number of capacitive sensing units, arranged in a form of an array, wherein each of the number of capacitive sensing units switches between three states: sensing state, idle state, and emitting state; a driving source, for providing a driving signal to an adjacent finger overlying the number of capacitive sensing units through the number of capacitive sensing units which are in the emitting state; a number of driving switches, each connected between one of the number of capacitive sensing units and the driving source; and a control and timing logic, connected to each of the number of driving switches, for controlling the state of each of the number of capacitive sensing units.
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Citations
13 Claims
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1. A capacitive image sensor, comprising:
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a plurality of capacitive sensing units, arranged in a form of an array, wherein each of the plurality of capacitive sensing units switches between three states;
sensing state, idle state, and emitting state; and
each of the plurality of capacitive sensing units comprises;a sensing electrode; and a voltage follower, having an input node connected to the sensing electrode; a driving source, for providing a driving signal to an adjacent finger overlying the plurality of capacitive sensing units through the plurality of capacitive sensing units which are in the emitting state; a plurality of driving switches, each connected between one of the plurality of capacitive sensing units and the driving source; and a control and timing logic, connected to each of the plurality of driving switches, for controlling the state of each of the plurality of capacitive sensing units, wherein an electric potential of the sensing electrode is set to a predetermined voltage and changes in response to the driving signal provided to the adjacent finger while the capacitive sensing unit is in the sensing state;
the electric potential of the sensing electrode is driven by the driving source while the capacitive sensing unit is in the emitting state;
the electric potential of the sensing electrode is set to a constant voltage or left floating while the capacitive sensing unit is in the idle state;
the driving signal has a positive waveform or a negative waveform formed by a potential change or potential changes of the driving source;
the electric potential of each of the plurality of capacitive sensing units is reset before the driving signal is provided to the adjacent finger through the plurality of capacitive sensing units which are in the emitting state. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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Specification