US 7,489,135 B2
	Electric potential measuring instrument and image forming apparatus
Yoshikatsu Ichimura, Tokyo (Japan)
Assigned to Canon Kabushiki Kaisha, Tokyo (Japan)
Appl. No. 11/579,769 PCT Filed Jun. 07, 2005, PCT No. PCT/JP2005/010758 § 371(c)(1), (2), (4) Date Nov. 08, 2006, PCT Pub. No. WO2005/121819, PCT Pub. Date Dec. 22, 2005.
Claims priority of application No. 2004-169274 (JP), filed on Jun. 08, 2004.
Prior Publication US 2007/0229086 A1, Oct. 04, 2007
Int. Cl. G01R 29/12 (2006.01)

U.S. Cl. 324—457  [324/72; 324/663; 324/458; 318/652; 399/73; 257/314]

8 Claims

1. An electric potential measuring instrument comprising a semiconductor substrate arranged at a position opposite to an object of measurement, an electrode arranged on said semiconductor substrate, and modulation means for modulating the coupling capacitance between the object of measurement and said electrode, wherein said electrode is the gate electrode of a field effect type transistor formed on said semiconductor substrate.