# US 7,612,570 B2 · Surface-potential distribution measuring apparatus, image carrier, and image forming apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,612,570 B2 - Document ID: US7612570B2 - Status: Granted - Kind: B2 - Application number: 11/847,790 - Filed: 2007-08-30 - Published: 2008-03-06 - Granted: 2009-11-03 - Earliest claimed: 2006-08-30 - Assignees: Ricoh Company, Ltd. - Inventors: Hiroyuki Suhara - Web page: https://patentgrep.com/patent/US7612570B2 ## CPC - G01R 31/305: using electron beams {(investigating or analysing materials by measuring photoelectric effect G01N23/227)} - G03G 15/5037: {the characteristics being an electrical parameter, e.g. voltage} - H01J 37/244: Detectors; Associated components or circuits therefor - H01J 37/268: {with scanning beams} - G03G 2215/00033: on recording member - G03G 2215/00054: Electrostatic image detection - H01J 2237/0047: using electromagnetic radiations, e.g. UV, X-rays, light - H01J 2237/0048: Charging arrangements - H01J 2237/2444: Electron Multiplier - H01J 2237/24564: Measurements of electric or magnetic variables, e.g. voltage, current, frequency - H01J 2237/2594: Measuring electric fields or potentials - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) - G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY - H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H) ## Abstract A surface-potential distribution measuring apparatus includes an electron gun, an electron-beam optical system, an electron-emission panel, a detector, and a control system. The electron-beam optical system is located between the electron gun and a sample, and focuses a beam of electrons emitted from the electron gun to the surface of the sample. The electron-emission panel is located near the sample to be collided with at least part of the electrons via the sample, and emits secondary electrons corresponding to the number of collided electrons. The detector detects at least part of the secondary electrons. The control system obtains potential distribution on the surface of the sample based on a detection result obtained by the detector. ## Claims ### Claim 1 A surface-potential distribution measuring apparatus that measures a potential distribution of a latent image on a surface of a sample by scanning the surface with a beam of charged particles, the surface-potential distribution measuring apparatus comprising: an image forming unit that forms the latent image on the surface of the sample by distributing a charge potential on the surface of the sample; a beam generating unit that generates a beam of charged particles; an optical system that is located between the beam generating unit and the sample, and focuses the beam from the beam generating unit to the surface of the sample; a particle emitting member that is located near the sample to be collided with at least part of the charged particles via the sample, and emits secondary charged particles corresponding to number of collided charged particles; a detecting unit that detects at least part of the secondary charged particles; and a calculating unit that calculates the potential distribution of a latent image pattern formed on the surface of the sample by the image forming unit based on a detection result obtained by the detecting unit. ### Claim 2 (depends on 1) The surface-potential distribution measuring apparatus according to claim 1, wherein the particle emitting member faces the detecting unit. ### Claim 3 (depends on 1) The surface-potential distribution measuring apparatus according to claim 1, wherein the particle emitting member is located between the optical system and the sample, and includes an opening which the beam can pass through. ### Claim 4 (depends on 3) The surface-potential distribution measuring apparatus according to claim 3, wherein a diameter of the opening is equal to or smaller than 2 millimeters. ### Claim 5 (depends on 1) The surface-potential distribution measuring apparatus according to claim 1, wherein the particle emitting member has a smooth surface against which at least part of the charged particles collides. ### Claim 6 (depends on 1) The surface-potential distribution measuring apparatus according to claim 1, wherein the particle emitting member includes a first surface against which at least part of the charged particles collides, and a second surface on which a conductive film is formed, the second surface being opposite to the first surface. ### Claim 7 (depends on 1) The surface-potential distribution measuring apparatus according to claim 1, further comprising: a voltage applying unit that applies a voltage to the particle emitting member, and optimizes a ratio at which the particle emitting member emits the secondary charged particles. ### Claim 8 (depends on 1) The surface-potential distribution measuring apparatus according to claim 1, wherein the charged particles that collides with the particle emitting member via the sample have been repulsed near the surface of the sample before reaching the surface of the sample. ### Claim 9 (depends on 1) The surface-potential distribution measuring apparatus according to claim 1, further comprising: a latent-image forming unit that forms a latent image on the surface of the sample. ### Claim 10 A surface-potential distribution measuring apparatus that measures potential distribution on a surface of a sample by scanning the surface with a beam of charged particles, the surface-potential distribution measuring apparatus comprising: an image forming unit that forms a latent image on the surface of the sample by distributing a charge potential on the surface of the sample; a beam generating unit that generates a beam of charged particles; an optical system that is located between the beam generating unit and the sample, and focuses the beam from the beam generating unit to the surface of the sample; a reversed-particle detecting unit that is located near the sample and detects a repulsive particle which is in the beam of charged particles proceeding to the sample and is repulsed without reaching the sample; and a calculating unit that calculates potential distribution of a latent image pattern formed on the surface of the sample by the image forming unit based on a detection result obtained by the reversed-particle detecting unit. ### Claim 11 (depends on 10) The surface-potential distribution measuring apparatus according to claim 10, wherein the detecting unit is in a meshed configuration. ### Claim 12 (depends on 11) The surface-potential distribution measuring apparatus according to claim 11, wherein the detecting unit is made of nonmagnetic conductive material. ### Claim 13 (depends on 10) The surface-potential distribution measuring apparatus according to claim 10, wherein the detecting unit is located at least 0.1 millimeter above the surface of the sample. ### Claim 14 (depends on 10) The surface-potential distribution measuring apparatus according to claim 10, further comprising: a voltage control unit that changes an acceleration voltage of the beam. ### Claim 15 (depends on 10) The surface-potential distribution measuring apparatus according to claim 10, further comprising: a bias control unit that changes surface potential bias.