# US 2013/0278656 A1 · Determining an Issue with an Inkjet Nozzle Using an Impedance Difference > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0278656 A1 - Document ID: US20130278656A1 - Status: Published application - Kind: A1 - Application number: 13/450,620 - Filed: 2012-04-19 - Published: 2013-10-24 - Earliest claimed: 2012-04-19 - Assignees: Hewlett-Packard Development Company, L.P. - Inventors: Alexander Govyadinov; Andrew L. Van Brocklin; Eric T. Martin; David Maxfield - Web page: https://patentgrep.com/patent/US20130278656A1 ## CPC - B41J 2/2142: {Detection of malfunctioning nozzles (generating single droplets or particles on demand by pressure, e.g. electromechanical transducers B41J2/045, B41J2/05; jet deflection sensors B41J2/125; for cleaning purposes B41J2/16579)} - B41J 2/0451: {for detecting failure, e.g. clogging, malfunctioning actuator} - B41J 2/0458: {controlling heads based on heating elements forming bubbles} - B41J 2/14153: {Structures including a sensor} - B41J 2002/14354: {Sensor in each pressure chamber} - B41J: TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS ## Abstract A method for determining an issue with an inkjet nozzle using an impedance difference includes taking a first impedance measurement with a sensor to detect a drive bubble in an ink chamber after a drive bubble formation mechanism is activated; and subtracting the first impedance measurement from a reference. ## Claims ### Claim 1 A method for determining an issue with an inkjet nozzle using an impedance difference, the method comprising: taking a first impedance measurement with a sensor to detect a drive bubble in an ink chamber after a drive bubble formation mechanism is activated; and subtracting said first impedance measurement from a reference. ### Claim 2 (depends on 1) The method of claim 1, wherein said reference is an impedance value stored in memory. ### Claim 3 (depends on 1) The method of claim 1, wherein said reference is an impedance value derived from a second measurement taken with a second sensor and taken at substantially a same time as said first impedance measurement. ### Claim 4 (depends on 1) The method of claim 1, wherein said reference is an impedance value derived from an earlier measurement taken with said sensor and taken earlier than said first impedance measurement. ### Claim 5 (depends on 1) The method of claim 1, wherein said reference is an impedance value derived from a second measurement taken with a second sensor to detect a second drive bubble in a second ink chamber. ### Claim 6 (depends on 1) The method of claim 1, further comprising taking a second impedance measurement with a second sensor in said ink chamber at substantially a same time as said first impedance measurement; and subtracting said second measurement from said reference. ### Claim 7 (depends on 1) The method of claim 1, further comprising determining said issue exists based on a difference between said first impedance measurement and said reference. ### Claim 8 (depends on 7) The method of claim 7, further comprising compensating for said issue with a second inkjet nozzle. ### Claim 9 (depends on 1) The method of claim 1, wherein said issue is a blocked nozzle passage, a weak bubble formation, presence of a stray bubble, blocked ink chamber inlet, or combinations thereof. ### Claim 10 An ink jet print head, comprising, a first ink chamber comprising a drive bubble formation mechanism and an impedance sensor positioned to detect a presence of a drive bubble in said first ink chamber; and said impedance sensor being in communication with a processor programmed to determine a difference between an impedance measurement taken with said impedance sensor and an impedance reference value. ### Claim 11 (depends on 10) The print head of claim 10, wherein a second impedance sensor positioned to detect said drive bubble in said first ink chamber and is in communication with said processor and said processor is programmed to receive said impedance reference value from said second impedance sensor. ### Claim 12 (depends on 10) The print head of claim 10, wherein said processor is in communication with a second ink chamber in said print head. ### Claim 13 (depends on 12) The print head of claim 12, wherein said processor is programmed to instruct components within said second ink chamber to compensate for said first ink chamber when said processor determines that said first ink chamber has an issue based off of said difference between said impedance measurement and said impedance reference value. ### Claim 14 A printer, comprising, an ink chamber comprising a drive bubble formation mechanism and a first impedance sensor and a second impedance sensor positioned within said ink chamber to detect a presence of a bubble; and said first and second impedance sensors being in communication with a differential amplifier programmed to determine a difference between a first impedance measurement taken with said first impedance sensor and a second impedance measurement taken with said second impedance sensor. ### Claim 15 (depends on 14) The printer of claim 14, wherein said differential amplifier is in communication with logic programmed to determine if an issue exists in said ink chamber based on of said difference between said first impedance measurement said second impedance measurement.