Apparatus for detecting surface potential distribution

Claim 1

An apparatus for detecting a distribution of a surface potential on a measured object, comprising: a light source emitting light; a sensing head opposing the measured object and including an optical modulator layer for modulating the light emitted from the light source and outputting light, a transparent electrode for applying an electric field to the optical modulator layer, and a dielectric mirror for reflecting the light after the light passes through the optical modulator layer; means for applying the light from the light source to the sensing head; means for detecting the light outputted from the sensing head; means for periodically moving the sensing head relative to the measured object between a first position and a second position separated from the measured object by different distances respectively; a line memory; means for enabling the sensing head to scan one line of the measured object while the sensing head is in the first position; means for writing an output signal from the light-detecting means into the line memory while the sensing head is in the first position; means for enabling the sensing head to scan said line of the measured object while the sensing head is in the second position; means for reading out the written signal from the line memory while the sensing head is in the second position; and means for subtracting the output signal from the light-detecting means from the read out signal while the sensing head is in the second position.

Claim 2

An apparatus for detecting a distribution of a surface potential on a measured object, comprising: a light source emitting light; a sensing head opposing the measured object and including an optical modulator layer for modulating the light emitted from the light source and outputting light, a transparent electrode for applying an electric field to the optical modulator layer, and a dielectric mirror for reflecting the light after the light passes through the optical modulator layer; means for applying the light from the light source to the sensing head; means for detecting the light outputted from the sensing head; means for periodically moving the sensing head relative to the measured object between a first position and a second position separated from the measured object by different distances respectively; a line memory; means for enabling the sensing head to scan one line of the measured object while the sensing head is in the first position; means for writing an output signal from the light-detecting means into the line memory while the sensing head is in the first position; means for enabling the sensing head to scan said line of the measured object while the sensing head is in the second position; means for reading out the written signal from the line memory while the sensing head is in the second position; and means for subtracting the output signal from the light-detecting means from the read out signal while the sensing head is in the second position.

Claim 3

An apparatus comprising: a recording member having first regions and second regions alternating with each other, the first regions having first-type potentials and the second regions having second-type potentials different from the first-type potentials; means for forming a charge latent image on the recording member in accordance with an information signal; a reading head opposing the recording member and including an optical modulator subjected to an electric field representative of the charge latent image; and means for reciprocating the reading head relative to the recording member along a surface of the recording member to vary the electric field applied to the optical modulator in an alternating manner.

Claim 4

An apparatus comprising: a recording member having first regions and second regions alternating with each other, the first regions having first-type potentials and the second regions having second-type potentials different from the first-type potentials; means for forming a charge latent image on the recording member in accordance with an information signal; a reading head opposing the recording member and including an optical modulator subjected to an electric field representative of the charge latent image; and means for reciprocating the reading head relative to the recording member along a surface of the recording member to vary the electric field applied to the optical modulator in an alternating manner.