| 摘要 |
PROBLEM TO BE SOLVED: To reduce a measuring error of a potential measuring apparatus, to rectify a line of electric force from a photoconductor, to reduce the change in an output from a probe due to a change in a measuring distance, and to make a visual field circular. SOLUTION: A detecting window 46 in a probe 12 is arranged so as to face a photoconductor 14. A line of electric force E which is passed through the detecting window 46 is detected by a detecting electrode 56 which is housed inside, is sent to an ESV circuit board as a detection signal, and the surface potential of the photoconductor 14 is measured. A guard electrode part 44 is connected electrically to the probe 12, and when a measuring potential is given to the probe 12, the same measuring potential is applied also to the guard electrode 44. As a result, a space whose potential is identical to that of the photoconductor 14 is spread in the probe 12 and the guard electrode part 44. The line of electric force from a cover 24 which is charged with electricity due to an ionic wind or the like does not reach the detecting window. The line of electric force E from the cover 24 is shielded. |
