# US 5,708,915 A · Image-quality stabilizer for use in an electrophotographic apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,708,915 A - Document ID: US5708915A - Status: Granted - Kind: A - Application number: 08/636,914 - Filed: 1996-04-24 - Granted: 1998-01-13 - Earliest claimed: 1992-11-18 - Assignees: Sharp Kabushiki Kaisha - Inventors: Teruhiko Noguchi; Jitsuo Masuda; Katsushi Inoue - Web page: https://patentgrep.com/patent/US5708915A ## CPC - G03G 15/0266: {Arrangements for controlling the amount of charge} - G03G 15/5041: {Detecting a toner image, e.g. density, toner coverage, using a test patch (G03G15/553 takes precedence)} - G03G 2215/00042: Optical detection - G03G 2215/00054: Electrostatic image detection - G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY ## Abstract An image-quality stabilizer in a copying machine feedback-controls a charger output according to an amount of toner on a photoreceptor drum detected by a patch sensor during a rotation of the photoreceptor drum after a copying operation. The image-quality stabilizer counts time that the copying machine is unused, i.e., time that the photoreceptor drum is stopped being rotated using a timer, and one-way controls the charger output according to the time immediately before the next copying operation. With these controlling operations, it is possible to correct a change in the copy density which is caused when the copying machine is used or left unused without increasing the consumption of toner and impairing the responsiveness of the copying machine, thereby achieving stable image quality. ## Claims ### Claim 1 An image-quality stabilizer comprising: image forming means for forming an image using a photoreceptor; reference toner image forming means for forming on said photoreceptor a reference toner image for image-quality adjusting; detecting means for detecting an amount of the reference toner image formed on said photoreceptor; a first timer for counting time that said photoreceptor is inactive; image-quality adjusting means for controlling said reference toner image forming means, so as to form the reference toner image on said photoreceptor, and for controlling said detecting means so as to detect the amount of the reference toner image formed on said photoreceptor, the controlling being carried out using a rotation of said photoreceptor performed after an image formation by said image forming means, and for controlling, so as to maintain a predetermined relationship, said image forming means in accordance with (a) a value detected by said detecting means and (b) an inactive time, of said photoreceptor, counted by said first timer. ### Claim 2 (depends on 1) The image-quality stabilizer according to claim 1, further comprising memory means for storing a correct value of said image forming means, the correct value being determined to change gradually according to time that said photoreceptor is inactive, wherein said image-quality adjusting means controls said image forming means to have the correct value stored in said memory means according to time counted by said first timer. ### Claim 3 (depends on 1) The image-quality stabilizer according to claim 1, further comprising memory means for storing surface-potential recovery characteristics of said photoreceptor which is approximated as a function of time that said photoreceptor is inactive, wherein said image-quality adjusting means calculates a recovery of surface potential of said photoreceptor according to a value detected by said first timer using the function, and controls said image forming means so as to adjust the recovery. ### Claim 4 (depends on 1) The image-quality stabilizer according to claim 1, wherein said image forming means is charging means. ### Claim 5 (depends on 1) The image-quality stabilizer according to claim 1, wherein said image forming means is developing means. ### Claim 6 (depends on 1) The image-quality stabilizer according to claim 1, wherein said image forming means is discharging means. ### Claim 7 (depends on 1) The image-quality stabilizer according to claim 1, wherein said image forming means is exposure means. ### Claim 8 (depends on 1) The image-quality stabilizer according to claim 1, wherein said image-quality adjusting means includes control means which controls at least one of charging means, developing means; and discharging means as well as exposure means. ### Claim 9 An image-quality stabilizer for use in an electrophotographic apparatus including a photoreceptor, and image forming means for performing an image-forming operation using said photoreceptor, said image-quality stabilizer comprising: toner detecting means for detecting an amount of toner forming a reference toner image on said photoreceptor; a first timer for detecting time that said photoreceptor is inactive; and image-quality adjusting means for controlling said image forming means at predetermined intervals according to a value detected by said toner detecting means so as to cause the amount of toner forming the reference toner image to be equal to a predetermined reference value, and for controlling said image forming means according to a value detected by said first timer so as to maintain a predetermined relationship. ### Claim 10 (depends on 9) The image-quality stabilizer according to claim 9, wherein the predetermined intervals at which said image-quality adjusting means controls said image forming means are given by the number of times the image-forming operation is performed. ### Claim 11 (depends on 9) The image-quality stabilizer according to claim 9, wherein the predetermined intervals at which said image-quality adjusting means controls said image forming means are given by a period of time. ### Claim 12 (depends on 9) The image-quality stabilizer according to claim 9, further comprising memory means for storing a correct value which varies according to time that said photoreceptor is inactive, wherein said image-quality adjusting means controls said image forming means to have a correct value according to a value detected by said first timer. ### Claim 13 (depends on 9) The image-quality stabilizer according to claim 9, further comprising memory means for storing surface-potential recovery characteristics of said photoreceptor approximated as a function of time that said photoreceptor is inactive, wherein said image-quality adjusting means calculates a recovery of surface potential of said photoreceptor from the time detected by said first timer using the function, and controls said image forming means so as to adjust the recovery. ### Claim 14 (depends on 9) The image-quality stabilizer according to claim 9, wherein said image forming means is charging means. ### Claim 15 (depends on 9) The image-quality stabilizer according to claim 9, wherein said image forming means is developing means. ### Claim 16 (depends on 9) The image-quality stabilizer according to claim 9, wherein said image forming means is discharging means. ### Claim 17 (depends on 9) The image-quality stabilizer according to claim 9, wherein said image forming means is exposure means. ### Claim 18 (depends on 9) The image-quality stabilizer according to claim 9, wherein said image-quality adjusting means includes control means which controls at least one of charging means, developing means, and discharging means as well as exposure means. ### Claim 19 An image-quality stabilizer for use in an electrophotographic apparatus including a photoreceptor, and image forming means for forming an image using said photoreceptor, said image-quality stabilizer comprising: toner detecting means for detecting an amount of toner forming a reference toner image on said photoreceptor; a first timer for counting time that said photoreceptor is inactive; and a second timer for counting time that said photoreceptor is active; image-quality adjusting means for controlling said image forming means according to the time counted by said second timer by taking account of surface-potential lowering characteristics of said photoreceptor relating to fatigue of said photoreceptor, controlling said image forming means according to the time counted by said first timer by taking account of surface-potential recovery characteristics, and controlling said image forming means at predetermined intervals according to a value detected by said toner detecting means so as to cause the amount of toner forming the reference toner image to be equal to a predetermined reference value. ### Claim 20 (depends on 19) The image-quality stabilizer according to claim 19, wherein said image forming means is charging means. ### Claim 21 (depends on 19) The image-quality stabilizer according to claim 19, wherein said image forming means is developing means. ### Claim 22 (depends on 19) The image-quality stabilizer according to claim 19, wherein said image forming means is discharging means. ### Claim 23 (depends on 19) The image-quality stabilizer according to claim 19, wherein said image forming means is exposure means. ### Claim 24 (depends on 19) The image-quality stabilizer according to claim 19, wherein said image-quality adjusting means includes control means which controls at least one of charging means, developing means, and discharging means as well as exposure means. ### Claim 25 An image-quality stabilizer comprising: image forming means for forming an image using a photoreceptor; reference latent image forming means for forming on said photoreceptor a reference latent image for image-quality adjusting; detecting means for detecting an amount of charges forming the reference latent image formed on said photoreceptor; a first timer for counting time that said photoreceptor is inactive; image-quality adjusting means for controlling said reference latent image forming means so as to form the reference latent image on said photoreceptor and controlling said detecting means so as to detect the amount of charges forming the reference latent image formed on said photoreceptor, the controlling being carried out using a rotation of said photoreceptor performed after an image formation by said image forming means, and for controlling, so as to maintain a predetermined relationship, said image forming means in accordance with (a) a value detected by said detecting means and (b) an inactive time, of said photoreceptor, counted by said first timer. ### Claim 26 (depends on 25) The image-quality stabilizer according to claim 25, further comprising memory means for storing a correct value of said image forming means, the correct value being determined to change gradually according to the time that said photoreceptor is inactive, wherein said image-quality adjusting means controls said image forming means to have the correct value stored in said memory means according to the time counted by said first timer. ### Claim 27 (depends on 25) The image-quality stabilizer according to claim 25, further comprising memory means for storing surface-potential recovery characteristics of said photoreceptor which is approximated as a function of time that said photoreceptor is inactive, wherein said image-quality adjusting means calculates a recovery of surface potential of said photoreceptor from the time counted by said first timer using the function, and controls said image forming means so as to adjust the recovery. ### Claim 28 (depends on 25) The image-quality stabilizer according to claim 25, wherein said image forming means is charging means. ### Claim 29 (depends on 25) The image-quality stabilizer according to claim 25, wherein said image forming means is developing means. ### Claim 30 (depends on 25) The image-quality stabilizer according to claim 25, wherein said image forming means is discharging means. ### Claim 31 (depends on 25) The image-quality stabilizer according to claim 25, wherein said image forming means is exposure means. ### Claim 32 (depends on 25) The image-quality stabilizer according to claim 25, wherein said image-quality adjusting means includes control means which controls at least one of charging means, developing means, and discharging means as well as exposure means. ### Claim 33 An image-quality stabilizer for use in an electrophotographic apparatus including a photoreceptor and image forming means for performing an image-forming operation using said photoreceptor, said image-quality stabilizer comprising: charge detecting means for detecting an amount of charges forming a reference latent image on said photoreceptor; a first timer for detecting time that said photoreceptor is inactive; and image-quality adjusting means for controlling said image forming means at predetermined intervals according to a value detected by said charge detecting means so as to cause the amount of charges forming the reference latent image to be equal to a predetermined reference value, and for controlling said image forming means according to the time counted by said first timer so as to maintain a predetermined relationship. ### Claim 34 (depends on 33) The image-quality stabilizer according to claim 33, wherein the predetermined intervals at which said image-quality adjusting means controls said image forming means are given by the number of times the image-forming operation is performed. ### Claim 35 (depends on 33) The image-quality stabilizer according to claim 33, wherein the predetermined intervals at which said image-quality adjusting means controls said image forming means are given by a period of time. ### Claim 36 (depends on 33) The image-quality stabilizer according to claim 33, further comprising memory means for storing a correct value of said image forming means, the correct value being determined to change gradually according to the time that said photoreceptor is inactive, wherein said image-quality adjusting means controls said image forming means to have the correct value stored in said memory means according to the time counted by said first timer. ### Claim 37 (depends on 33) The image-quality stabilizer according to claim 33, further comprising memory means for storing surface-potential recovery characteristics of said photoreceptor which is approximated as a function of time that said photoreceptor is inactive, wherein said image-quality adjusting means calculates a recovery of surface potential of said photoreceptor from the time detected by said first timer using the function, and controls said image forming means so as to adjust the recovery. ### Claim 38 (depends on 33) The image-quality stabilizer according to claim 33, wherein said image forming means is charging means. ### Claim 39 (depends on 33) The image-quality stabilizer according to claim 33, wherein said image forming means is developing means. ### Claim 40 (depends on 33) The image-quality stabilizer according to claim 33, wherein said image forming means is discharging means. ### Claim 41 (depends on 33) The image-quality stabilizer according to claim 33, wherein said image forming means is exposure means. ### Claim 42 (depends on 33) The image-quality stabilizer according to claim 33, wherein said image-quality adjusting means includes control means which controls at least one of charging means, developing means, and discharging means as well as exposure means. ### Claim 43 An image-quality stabilizer for use in an electrophotographic apparatus including a photoreceptor and image forming means for performing an image-forming operation using said photoreceptor, said image-quality stabilizer comprising: charge detecting means for detecting an amount of charges forming a reference latent image on said photoreceptor; a first timer for detecting time that said photoreceptor is inactive; a second timer for detecting time that said photoreceptor is active; and image-quality adjusting means for controlling said image forming means according to a value detected by said charge detecting means by taking account of surface-potential lowering characteristics of said photoreceptor relating to fatigue of said photoreceptor, controlling said image forming means according to the time counted by said first timer by taking account of surface-potential recovery characteristics of said photoreceptor, and controlling said image forming means at predetermined intervals according to a value detected by said charge detecting means so as to cause the amount of charges forming a reference latent image on said photoreceptor to be equal to a predetermined reference value. ### Claim 44 (depends on 43) The image-quality stabilizer according to claim 43, wherein said image forming means is charging means. ### Claim 45 (depends on 43) The image-quality stabilizer according to claim 43, wherein said image forming means is developing means. ### Claim 46 (depends on 43) The image-quality stabilizer according to claim 43, wherein said image forming means is discharging means. ### Claim 47 (depends on 43) The image-quality stabilizer according to claim 43, wherein said image forming means is exposure means. ### Claim 48 (depends on 43) The image-quality stabilizer according to claim 43, wherein said image-quality adjusting means includes control means which controls at least one of charging means, developing means, and discharging means as well as exposure means. ### Claim 49 An image-quality stabilizer for use in an electrophotographic apparatus including a photoreceptor and image forming means for performing an image-forming operation using said photoreceptor, said image-quality stabilizer comprising: toner detecting means for detecting an amount of toner forming a reference toner image on said photoreceptor; a first timer for detecting time that said photoreceptor is inactive; a second timer for detecting an accumulated time of image-forming operations; and image-quality adjusting means for controlling said image forming means according to a value detected by said toner detecting means so as to cause an amount of toner forming the reference toner image to be equal to a predetermined reference value when the accumulated time counted by said second timer reaches a predetermined time, and controlling said image forming means according to time that said photoreceptor is inactive if the time counted by said first timer reaches a predetermined time. ### Claim 50 (depends on 49) The image-quality stabilizer according to claim 49, wherein said image forming means is charging means. ### Claim 51 (depends on 49) The image-quality stabilizer according to claim 49, wherein said image forming means is developing means. ### Claim 52 (depends on 49) The image-quality stabilizer according to claim 49, wherein said image forming means is discharging means. ### Claim 53 (depends on 49) The image-quality stabilizer according to claim 49, wherein said image forming means is exposure means. ### Claim 54 (depends on 49) The image-quality stabilizer according to claim 49, wherein said image-quality adjusting means includes control means which controls at least one of charging means, developing means, and discharging means as well as exposure means. ### Claim 55 An image-quality stabilizer for use in an electrophotographic apparatus including a photoreceptor and image forming means for performing an image-forming operation using said photoreceptor, said image-quality stabilizer comprising: charge detecting means for detecting an amount of charges forming a reference latent image on said photoreceptor; a first timer for detecting time that said photoreceptor is inactive; a second timer for detecting an accumulated time of image-forming operations; and image-quality adjusting means for controlling said image forming means according to a value detected by said charge detecting means so as to cause an amount of charges forming the reference latent image to be equal to a predetermined reference value when the accumulated time counted by said second timer reaches a predetermined time, and controlling said image forming means according to the time that said photoreceptor is inactive if the time counted by said first timer reaches a predetermined time. ### Claim 56 (depends on 55) The image-quality stabilizer according to claim 55, wherein said image forming means is charging means. ### Claim 57 (depends on 55) The image-quality stabilizer according to claim 55, wherein said image forming means is developing means. ### Claim 58 (depends on 55) The image-quality stabilizer according to claim 55, wherein said image forming means is discharging means. ### Claim 59 (depends on 55) The image-quality stabilizer according to claim 55, wherein said image forming means is exposure means. ### Claim 60 (depends on 55) The image-quality stabilizer according to claim 55, wherein said image-quality adjusting means includes control means which controls at least one of charging means, developing means, and discharging means as well as exposure means. ### Claim 61 A method of controlling image quality with an image-quality stabilizer in an electrophotographic apparatus including a photoreceptor and image forming means, comprising the steps of: forming a reference toner image on said photoreceptor during a rotation of said photoreceptor performed after an image-forming operation; detecting means for detecting an amount of toner forming the reference toner image; controlling said image forming means so as to cause a detected amount of toner on said photoreceptor to be equal to a predetermined reference value every port-rotation of said photoreceptor; detecting time that said photoreceptor is inactive if said photoreceptor is left unused after the image forming operation; and controlling said image forming means according to the detected time so as to maintain a predetermined relationship. ### Claim 62 A method of controlling image quality with an image-quality stabilizer in an electrophotographic apparatus including a photoreceptor and image forming means, comprising the steps of: forming a reference toner image on said photoreceptor at predetermined intervals; detecting an amount of toner forming the reference toner image; controlling said image forming means so as to cause a detected amount of toner on said photoreceptor to be equal to a predetermined reference value; detecting time that said photoreceptor is inactive if said photoreceptor is left unused after the image forming operation; and controlling said image forming means according to the detected time so as to maintain a predetermined relationship. ### Claim 63 A method of controlling image quality with an image-quality stabilizer in an electrophotographic apparatus including a photoreceptor and image forming means, comprising the steps of: detecting time that said photoreceptor is active; controlling said image forming means according to the detected time by taking account of surface-potential lowering characteristics of said photoreceptor relating to fatigue of said photoreceptor; detecting time that said photoreceptor is inactive; controlling said image forming means according to the detected time that said photoreceptor is inactive by taking account of surface-potential recovery characteristics; forming a reference toner image on said photoreceptor at predetermined intervals; detecting an amount of toner forming the reference toner image on said photoreceptor; and controlling said image forming means at predetermined intervals so as to cause the detected amount of toner to be equal to a predetermined reference value. ### Claim 64 A method of controlling image quality with an image-quality stabilizer in an electrophotographic apparatus including a photoreceptor and image forming means, comprising the steps of: forming a reference latent image on said photoreceptor during a rotation of said photoreceptor performed after an image-forming operation; detecting an amount of charges forming the reference latent image on said photoreceptor; controlling said image forming means so as to cause a detected amount of charges to be equal to a predetermined reference value every post-rotation of said photoreceptor; detecting time that said photoreceptor is inactive if said photoreceptor is inactive after the image forming operation; and controlling said image forming means according to the detected time that said photoreceptor is inactive so as to maintain a predetermined relationship. ### Claim 65 A method of controlling image quality with an image-quality stabilizer in an electrophotographic apparatus including a photoreceptor and image forming means, comprising the steps of: forming a reference latent image on said photoreceptor at predetermined intervals; detecting an amount of charges forming the reference latent image on said photoreceptor; controlling said image forming means so as to cause a detected amount of charges to be equal to a predetermined reference value; detecting time that said photoreceptor is inactive if said photoreceptor is left unused after the image forming operation; and controlling said image forming means according to the detected time that said photoreceptor is inactive so as to maintain a predetermined relationship. ### Claim 66 A method of controlling image quality with an image-quality stabilizer in an electrophotographic apparatus including a photoreceptor and image forming means, comprising the steps of: detecting time that said photoreceptor is active; controlling said image forming means according to the detected time by taking account of surface-potential lowering characteristics of said photoreceptor relating to fatigue of said photoreceptor; detecting time that said photoreceptor is inactive; controlling said image forming means according to the detected time that said photoreceptor is inactive by taking account of surface-potential recovery characteristics of said photoreceptor; forming a reference latent image on a photoreceptor at predetermined intervals; detecting an amount of charges forming the reference latent image on said photoreceptor; controlling said image forming means at predetermined intervals so as to cause a detected amount of charges to be equal to a predetermined reference value. ### Claim 67 A method of controlling image quality with an image-quality stabilizer in an electrophotographic apparatus including a photoreceptor and image forming means, comprising the steps of: detecting an accumulated time of image forming operations; forming a reference toner image on said photoreceptor when the accumulated time reaches a predetermined time; detecting an amount of toner forming the toner image; controlling said image forming means so as to cause the detected toner amount to be equal to a predetermined reference value; detecting time that said photoreceptor is inactive; and controlling said image forming means according to the detected time that said photoreceptor is inactive. ### Claim 68 A method of controlling image quality with an image-quality stabilizer in an electrophotographic apparatus including a photoreceptor and image forming means, comprising the steps of: detecting an accumulated time of image forming operations; forming a reference latent image on said photoreceptor when the accumulated time reaches a predetermined time; detecting an amount of charges forming the reference latent image; controlling said image forming means so as to cause the detected amount of charges to be equal to a predetermined reference value; detecting time that said photoreceptor is inactive; and controlling said image forming means according to the detected time that said photoreceptor is inactive.