Method for capacitive image acquisition
First Claim
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1. A method for capacitive image acquisition, which comprises:
- a) dividing an area to be acquired as an image in a grid-shaped array into pixels assigned an assembly of electrical conductors comprising, for each pixel, a measuring conductor and a shielding conductor;
b) placing the area to be acquired as an image opposite the measuring conductors, so that a capacitance is present between the pixels and the measuring conductors in each case dependent on the relevant pixel;
c) at each pixel, connecting the measuring conductor and the shielding conductor to the same electrical potential and disconnecting from the potential;
d) at each pixel, discharging a charge present on one of the measuring conductor and the shielding conductor onto a respective collecting capacitor, and simultaneously compensating a potential difference between the measuring conductor and the shielding conductor; and
e) repeating steps c and d until the charges collected on the collecting capacitors have at least a value predetermined to be sufficient for a separate measurement of each collecting capacitor.
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Abstract
A grid-shaped array of conductor areas is used for capacitive image acquisition. Shielding conductors are disposed in each case between the conductors that are provided for measurement. During a plurality of charging and discharging cycles, the potential is always carried along on the conductors belonging to a respective pixel in order to prevent displacement currents between the shielding capacitors. By way of example, a compensation line with a feedback operational amplifier can be used for identically altering the electrical potentials on the conductors.
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Citations
3 Claims
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1. A method for capacitive image acquisition, which comprises:
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a) dividing an area to be acquired as an image in a grid-shaped array into pixels assigned an assembly of electrical conductors comprising, for each pixel, a measuring conductor and a shielding conductor;
b) placing the area to be acquired as an image opposite the measuring conductors, so that a capacitance is present between the pixels and the measuring conductors in each case dependent on the relevant pixel;
c) at each pixel, connecting the measuring conductor and the shielding conductor to the same electrical potential and disconnecting from the potential;
d) at each pixel, discharging a charge present on one of the measuring conductor and the shielding conductor onto a respective collecting capacitor, and simultaneously compensating a potential difference between the measuring conductor and the shielding conductor; and
e) repeating steps c and d until the charges collected on the collecting capacitors have at least a value predetermined to be sufficient for a separate measurement of each collecting capacitor. - View Dependent Claims (2, 3)
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Specification