# US 12,759,285 B2 · Printing apparatus, method for controlling printing apparatus, and storage medium > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,759,285 B2 - Document ID: US12759285B2 - Status: Granted - Kind: B2 - Application number: 18/544,581 - Filed: 2023-12-19 - Published: 2024-06-20 - Granted: 2026-10-13 - Earliest claimed: 2022-12-20 - Assignees: Canon Kabushiki Kaisha - Applicants: Canon Kabushiki Kaisha - Inventors: Keisuke Ujiie - Web page: https://patentgrep.com/patent/US12759285B2 ## CPC - B41J 2/0451: {for detecting failure, e.g. clogging, malfunctioning actuator} - B41J 29/393: Devices for controlling or analysing the entire machine {; Controlling or analysing mechanical parameters involving printing of test patterns} - B41J: TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS ## Abstract A printing apparatus includes a selection unit configured to select a predetermined number of nozzles from nozzles of a printhead including a plurality of nozzles configured to discharge a liquid droplet; and a detection unit configured to detect a discharge state of a liquid droplet by using the predetermined number of nozzles being selected. The selection unit selects the predetermined number of nozzles such that a nozzle having a discharge abnormality is not included in the predetermined number of nozzles. ## Claims ### Claim 1 A printing apparatus comprising: a selection unit configured to select a predetermined number of nozzles from nozzles of a printhead including a plurality of nozzles configured to discharge a liquid droplet; and a detection unit configured to detect a discharge state of a liquid droplet by using the predetermined number of nozzles being selected, wherein the selection unit selects the predetermined number of nozzles such that a nozzle having a discharge abnormality is not included in the predetermined number of nozzles, the selection unit selects the predetermined number of nozzles from nozzle groups having a same drive timing among the nozzles of the printhead, and when the predetermined number of nozzles being selected include a nozzle having a discharge abnormality, the selection unit replaces the nozzle having the discharge abnormality with a normal nozzle in the nozzle group from which the predetermined number of nozzles are selected. ### Claim 2 (depends on 1) The printing apparatus according to claim 1, wherein the selection unit selects the predetermined number of nozzles from a nozzle group, among the nozzle groups, that has a lowest number of nozzles having a discharge abnormality. ### Claim 3 (depends on 1) The printing apparatus according to claim 1, wherein the selection unit replaces the nozzle having the discharge abnormality with a normal nozzle having a use frequency equivalent to that of the nozzle having the discharge abnormality. ### Claim 4 (depends on 1) The printing apparatus according to claim 1, wherein the selection unit selects, as a spare group, a nozzle group of drive order being anterior or posterior with respect to the nozzle group. ### Claim 5 (depends on 4) The printing apparatus according to claim 4, wherein, when there is no normal nozzle in the nozzle group from which the predetermined number of nozzles are selected, the selection unit replaces the nozzle having the discharge abnormality with a normal nozzle in the nozzles in the spare group. ### Claim 6 (depends on 5) The printing apparatus according to claim 5, wherein the selection unit replaces the nozzle having the discharge abnormality with a normal nozzle among the nozzles in the spare group, the normal nozzle having a use frequency equivalent to that of the nozzle having the discharge abnormality. ### Claim 7 (depends on 4) The printing apparatus according to claim 4, wherein, when a number of nozzles having a discharge abnormality is greater than a predetermined value with respect to a candidate nozzle group in the spare group, the selection unit selects, as the spare group, a nozzle group in which the number of nozzles having a discharge abnormality is equal to or less than the predetermined value, and the drive order is changed. ### Claim 8 (depends on 1) The printing apparatus according to claim 1, wherein the detection unit includes a light-emitting unit configured to emit a light flux in a direction parallel to a discharge surface of the printhead, and a light-receiving unit configured to receive the light flux. ### Claim 9 (depends on 8) The printing apparatus according to claim 8, wherein the detection unit detects a discharge state of a liquid droplet, based on a change of an output signal of the light-receiving unit when the liquid droplet discharged from the nozzle crosses the light flux. ### Claim 10 (depends on 9) The printing apparatus according to claim 9, wherein the detection unit detects a discharge amount of the liquid droplet, based on a degree of a change of an output signal of the light-receiving unit. ### Claim 11 (depends on 9) The printing apparatus according to claim 9, wherein the detection unit detects a discharge speed of the liquid droplet based on a timing of a change of an output signal of the light-receiving unit. ### Claim 12 A method of controlling a printing apparatus, the method comprising: selecting a predetermined number of nozzles from nozzles of a printhead including a plurality of nozzles configured to discharge a liquid droplet; and detecting a discharge state of a liquid droplet by using the predetermined number of nozzles being selected, wherein the selecting selects the predetermined number of nozzles such that a nozzle having a discharge abnormality is not included in the predetermined number of nozzles, in the selecting, the predetermined number of nozzles are selected from nozzle groups having a same drive timing among the nozzles of the printhead, and when the predetermined number of nozzles being selected include a nozzle having a discharge abnormality, the nozzle having the discharge abnormality is replaced with a normal nozzle in the nozzle group from which the predetermined number of nozzles are selected. ### Claim 13 A non-transitory computer-readable storage medium storing a program for causing a computer to execute a method of controlling a printing apparatus, the method comprising: selecting a predetermined number of nozzles from nozzles of a printhead including a plurality of nozzles configured to discharge a liquid droplet; and detecting a discharge state of a liquid droplet by using the predetermined number of nozzles being selected, wherein the selecting selects the predetermined number of nozzles such that a nozzle having a discharge abnormality is not included in the predetermined number of nozzles, in the selecting, the predetermined number of nozzles are selected from nozzle groups having a same drive timing among the nozzles of the printhead, and when the predetermined number of nozzles being selected include a nozzle having a discharge abnormality, the nozzle having the discharge abnormality is replaced with a normal nozzle in the nozzle group from which the predetermined number of nozzles are selected.