# US 2016/0355014 A1 · Ink jet head and ink jet apparatus having the same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2016/0355014 A1 - Document ID: US20160355014A1 - Status: Published application - Kind: A1 - Application number: 15/176,265 - Filed: 2016-06-08 - Published: 2016-12-08 - Earliest claimed: 2015-06-08 - Assignees: Toshiba Tec Kabushiki Kaisha - Applicants: Toshiba Tec Kabushiki Kaisha - Inventors: Ryutaro KUSUNOKI; Shuhei YOKOHAMA; Meng Fei WONG - Web page: https://patentgrep.com/patent/US20160355014A1 ## CPC - B41J 2/14201: {Structure of print heads with piezoelectric elements} - B41J 2/04581: {controlling heads based on piezoelectric elements} - B41J 2/04588: {using a specific waveform} - B41J 2/14298: {of disc type} - B41J 2002/1437: {Back shooter} - B41J 2202/15: Moving nozzle or nozzle plate - B41J: TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS ## Abstract An ink jet head includes a pressure chamber connected to a nozzle, an actuator configured to cause liquid in the pressure chamber to be ejected from the nozzle by deforming a wall of the pressure chamber, and a drive circuit configured to apply voltage to the actuator to drive the actuator. When a droplet of the liquid is ejected from the nozzle, the voltage applied to the actuator is changed from a first value to a second value that causes the pressure chamber to expand, and then changed from a third value that is equal to the second value or between the first value and the second value to the first value after a time period λ, which is a primary natural oscillation period of the actuator when the pressure chamber and the nozzle are filled with the liquid. ## Claims ### Claim 1 An ink jet head, comprising: a pressure chamber connected to a nozzle; an actuator configured to cause liquid in the pressure chamber to be ejected from the nozzle by deforming a wall of the pressure chamber; and a drive circuit configured to apply voltage to the actuator to drive the actuator, wherein when a droplet of the liquid is ejected from the nozzle, the voltage applied to the actuator is changed from a first value to a second value that causes the pressure chamber to expand, and then changed from a third value that is equal to the second value, or between the first value and the second value, to the first value after a time period λ, which is a primary natural oscillation period of the actuator when the pressure chamber and the nozzle are filled with the liquid. ### Claim 2 (depends on 1) The ink jet head according to claim 1, wherein after the voltage is changed from the first value to the second value, the voltage is maintained at the second value for a time period λ/2, then changed to the third value, and then maintained at the third value for the time period λ/2. ### Claim 3 (depends on 1) The ink jet head according to claim 1, wherein after the voltage is changed from the first value to the second value, the voltage is continuously changed from the second value to the third value throughout the time period λ. ### Claim 4 (depends on 1) The ink jet head according to claim 1, wherein after the voltage is changed from the first value to the second value, the voltage is linearly changed from the second value to the third value throughout the time period λ. ### Claim 5 (depends on 1) The ink jet head according to claim 1, wherein a volume of the pressure chamber when the voltage is at the first value is smaller than the one when no voltage is applied to the actuator. ### Claim 6 (depends on 5) The ink jet head according to claim 5, wherein when the ink jet head is in a ready state during which no liquid is ejected from the nozzle, the voltage is maintained at the first value. ### Claim 7 (depends on 1) The ink jet head according to claim 1, wherein the third value is between the first value and the second value, and when a predetermined number of droplets of the liquid is ejected from the nozzle in a liquid ejection operation, the voltage is changed from the first value to the second value, repeatedly changed from the third value to the second value each time period λ the predetermined number of times, and then changed from the third value to the first value. ### Claim 8 (depends on 7) The ink jet head according to claim 7, wherein in each time period λ, the voltage is maintained at the second value for a time period λ/2, then changed to the third value, and then maintained at the third value for another time period λ/2. ### Claim 9 (depends on 7) The ink jet head according to claim 7, wherein in each time period λ, the voltage is continuously changed from the second value to the third value throughout the time period λ. ### Claim 10 (depends on 7) The ink jet head according to claim 7, wherein in each time period λ, the voltage is linearly changed from the second value to the third value throughout the time period λ. ### Claim 11 An ink jet head, comprising: a pressure chamber connected to a nozzle; an actuator configured to cause liquid in the pressure chamber to be ejected from the nozzle by deforming a wall of the pressure chamber; and a drive circuit configured to apply voltage to the actuator to drive the actuator, wherein when a predetermined number of droplets of the liquid is ejected from the nozzle, the voltage applied to the actuator is changed from a first value to a second value that causes the pressure chamber to expand, repeatedly changed from a third value that is between the first value and the second value to the second value each time period λ the predetermined number of times, and then changed from the third value to the first value, the time period λ being a primary natural oscillation period of the actuator when the pressure chamber and the nozzle are filled with the liquid. ### Claim 12 (depends on 11) The ink jet head according to claim 11, wherein in each time period λ, the voltage is maintained at the second value for a time period λ/2, then changed to the third value, and then maintained at the third value for the time period λ/2. ### Claim 13 (depends on 11) The ink jet head according to claim 11, wherein in said each time period λ, the voltage is continuously changed from the second value to the third value throughout the time period λ. ### Claim 14 (depends on 11) The ink jet head according to claim 11, wherein in said each time period λ, the voltage is linearly changed from the second value to the third value throughout the time period λ. ### Claim 15 (depends on 11) The ink jet head according to claim 11, wherein a volume of the pressure chamber when the voltage is at the first value is smaller than the one when no voltage is applied to the actuator. ### Claim 16 (depends on 11) The ink jet head according to claim 11, wherein when the ink jet head is in a ready state during which no liquid is ejected from the nozzle, the voltage is maintained at the first value. ### Claim 17 An ink jet apparatus, comprising: an ink jet head configured to eject ink; and a conveying device configured to convey a sheet as the ink jet head ejects the ink, to form an image on the sheet, wherein the ink jet head includes: a pressure chamber connected to a nozzle; an actuator configured to cause liquid in the pressure chamber to be ejected from the nozzle by deforming a wall of the pressure chamber; and a drive circuit configured to apply voltage to the actuator to drive the actuator, wherein when a droplet of the liquid is ejected from the nozzle, the voltage applied to the actuator is changed from a first value to a second value that causes the pressure chamber to expand, and then changed from a third value that is equal to the second value or between the first value and the second value to the first value after a time period λ, which is a primary natural oscillation period of the actuator when the pressure chamber and the nozzle are filled with the liquid. ### Claim 18 (depends on 17) The ink jet apparatus according to claim 17, wherein after the voltage is changed from the first value to the second value, the voltage is maintained at the second value for a time period λ/2, then changed to the third value, and then maintained at the third value for another time period λ/2. ### Claim 19 (depends on 17) The ink jet apparatus according to claim 17, wherein after the voltage is changed from the first value to the second value, the voltage is continuously changed from the second value to the third value throughout the time period λ. ### Claim 20 (depends on 17) The ink jet apparatus according to claim 17, wherein after the voltage is changed from the first value to the second value, the voltage is linearly changed from the second value to the third value throughout the time period λ.