# US 10,500,844 B2 · Waveform generating device and ink jet recording apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,500,844 B2 - Document ID: US10500844B2 - Status: Granted - Kind: B2 - Application number: 16/057,218 - Filed: 2018-08-07 - Published: 2019-03-28 - Granted: 2019-12-10 - Earliest claimed: 2017-09-22 - Assignees: Toshiba Tec Kabushiki Kaisha - Applicants: Toshiba Tec Kabushiki Kaisha - Inventors: Hiroyuki Watanabe; Jun Takamura; Noboru Nitta - Web page: https://patentgrep.com/patent/US10500844B2 ## CPC - B41J 2/0452: {reducing demand in current or voltage} - B41J 2/04573: {Timing; Delays} - B41J 2/04581: {controlling heads based on piezoelectric elements} - B41J 2/04588: {using a specific waveform} - B41J 2/0459: {Height of the driving signal being adjusted} - B41J 2202/10: Finger type piezoelectric elements - B41J 2202/12: with ink circulating through the whole print head - B41J: TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS ## Abstract According to one embodiment, a waveform generating device includes a head driver configured to apply a driving signal to an actuator to discharge ink from a pressure chamber connected to a nozzle, the driving signal including a first portion for reducing an ink pressure in the pressure chamber and a second portion for increasing the ink pressure in the pressure chamber. The second portion is increased in potential by a first potential increase when ink pressure in the pressure chamber is at a maxima and the second portion is further increased in potential by a second potential increase when the ink pressure of the pressure chamber is at a negative value after the first potential increase. ## Claims ### Claim 1 A waveform generating device, comprising: a head driver configured to apply a driving signal to an actuator to discharge ink from a pressure chamber connected to a nozzle, the driving signal including a first portion for reducing an ink pressure in the pressure chamber and a second portion for increasing the ink pressure in the pressure chamber, wherein the second portion is increased in potential by a first potential increase when ink pressure in the pressure chamber is at a maxima, and the second portion is further increased in potential by a second potential increase when the ink pressure of the pressure chamber is at a negative value after the first potential increase. ### Claim 2 (depends on 1) The waveform generating device according to claim 1, wherein the second portion is reduced in potential in a first stage by a first potential reduction and then again in a second stage by a second potential reduction. ### Claim 3 (depends on 2) The waveform generating device according to claim 2, wherein, when a time from a start of the second portion to the first potential reduction is set to P, and a time from the first potential reduction to the second potential reduction is set to v, the driving signal satisfies the following: P=−0.6v+2.63. ### Claim 4 (depends on 1) The waveform generating device according to claim 1, wherein the driving signal includes applying a zero potential for an interval between an end of the first portion and a start of the second portion. ### Claim 5 (depends on 1) The waveform generating device according to claim 1, wherein the pressure chamber is fluidly connected to an ink chamber, and a time length of the first portion is equal to a half time of a natural vibration period of ink in the ink chamber. ### Claim 6 (depends on 5) The waveform generating device according to claim 5, wherein the second portion is increased in potential by the second potential increase after a time equal to the half time of the natural vibration period elapses after the second potential increase. ### Claim 7 (depends on 5) The waveform generating device according to claim 5, wherein the second portion is reduced in potential by a first potential reduction after between 1.3 times and 1.6 times the half time of the natural vibration period of the ink in the ink chamber from a start of the second portion. ### Claim 8 An ink jet recording apparatus, comprising: a nozzle plate having a nozzle; an actuator configured to change a pressure of a pressure chamber connected to the nozzle; and a head driver configured to apply a driving signal to an actuator to discharge ink from the pressure chamber connected to the nozzle, the driving signal including a first portion for reducing an ink pressure in the pressure chamber and a second portion for increasing the ink pressure in the pressure chamber, wherein the second portion is increased in potential by a first potential increase when ink pressure in the pressure chamber is at a maxima, and the second portion is further increased in potential by a second potential increase when the ink pressure of the pressure chamber is at a negative value after the first potential increase. ### Claim 9 (depends on 8) The ink jet recording apparatus according to claim 8, wherein the second portion is reduced in potential in a first stage by a first potential reduction and then again in a second stage by a second potential reduction. ### Claim 10 (depends on 9) The ink jet recording apparatus according to claim 9, wherein, when a time from a start of the second portion to the first potential reduction is set to P, and a time from the first potential reduction to the second potential reduction is set to v, the driving signal satisfies the following: P=−0.6v+2.63. ### Claim 11 (depends on 8) The ink jet recording apparatus according to claim 8, wherein the driving signal includes applying a zero potential for an interval between an end of the first portion and a start of the second portion. ### Claim 12 (depends on 8) The ink jet recording apparatus according to claim 8, wherein the pressure chamber is fluidly connected to an ink chamber, and a time length of the first portion is equal to a half time of a natural vibration period of ink in the ink chamber. ### Claim 13 (depends on 12) The ink jet recording apparatus according to claim 12, wherein the second portion is increased in potential by the second potential increase after a time equal to the half time of the natural vibration period elapses after the second potential increase. ### Claim 14 (depends on 12) The ink jet recording apparatus according to claim 12, wherein the second portion is reduced in potential by a first potential reduction after between 1.3 times and 1.6 times the half time of the natural vibration period of the ink in the ink chamber from a start of the second portion. ### Claim 15 An inkjet head driving method, comprising: applying a driving signal to an actuator to discharge ink from a pressure chamber connected to a nozzle, the driving signal including a first portion for reducing an ink pressure in the pressure chamber and a second portion for increasing the ink pressure in the pressure chamber, wherein the second portion is increased in potential by a first potential increase when ink pressure in the pressure chamber is at a maxima, and the second portion is further increased in potential by a second potential increase when the ink pressure of the pressure chamber is at a negative value after the first potential increase. ### Claim 16 (depends on 15) The inkjet head driving method according to claim 15, wherein the second portion is reduced in potential in a first stage by a first potential reduction and then again in a second stage by a second potential reduction. ### Claim 17 (depends on 16) The inkjet head driving method according to claim 16, wherein, when a time from a start of the second portion to the first potential reduction is set to P, and a time from the first potential reduction to the second potential reduction is set to v, the driving signal satisfies the following: P=−0.6v+2.63. ### Claim 18 (depends on 15) The inkjet head driving method according to claim 15, wherein the driving signal includes applying a zero potential for an interval between an end of the first portion and a start of the second portion. ### Claim 19 (depends on 15) The inkjet head driving method according to claim 15, wherein the pressure chamber is fluidly connected to an ink chamber, and a time length of the first portion is equal to a half time of a natural vibration period of ink in the ink chamber. ### Claim 20 (depends on 19) The inkjet head driving method according to claim 19, wherein the second portion is increased in potential by the second potential increase after a time equal to the half time of the natural vibration period elapses after the second potential increase.