# US 12,179,483 B2 · Liquid ejection head > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,179,483 B2 - Document ID: US12179483B2 - Status: Granted - Kind: B2 - Application number: 18/160,910 - Filed: 2023-01-27 - Published: 2023-09-28 - Granted: 2024-12-31 - Earliest claimed: 2022-03-28 - Assignees: RISO Technologies Corporation - Applicants: RISO Technologies Corporation - Inventors: Yasuhito Kiji - Web page: https://patentgrep.com/patent/US12179483B2 ## CPC - B41J 2/04588: {using a specific waveform} - B41J 2/04581: {controlling heads based on piezoelectric elements} - B41J: TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS ## Abstract According to one embodiment, a liquid ejection head includes a nozzle plate, pressure chambers, actuators, and a drive circuit. The nozzle plate includes nozzles for ejecting liquid. The pressure chamber communicates with the nozzles. The actuator varies the volume of the pressure chamber according to a drive signal. The drive circuit generates the drive signal for driving the actuator. The ejection waveform in the drive signal includes an expansion potential difference changes that changes in stages and a contraction potential difference change that changes in stages. The drive circuit sets the timing of the stages to cancel the vibration of an acoustic resonance frequency in a frequency range higher than a main acoustic resonance frequency of the liquid in the pressure chamber. ## Claims ### Claim 1 A liquid ejection head, comprising: a nozzle plate including nozzles for ejecting liquid; a plurality of pressure chambers communicating with the nozzles; a plurality of actuators configured to vary the volume of the pressure chambers according to drive signals applied thereto; and a drive circuit configured to generates drive signals for driving the plurality of actuators, wherein the drive circuit generates a drive signal including an ejection waveform for an actuator with an expansion potential difference change that changes in stages and a contraction potential difference change that changes in stages, and sets the timing of the stages to cancels the vibration of an acoustic resonance frequency in a frequency range higher than a main acoustic resonance frequency of a liquid in the pressure chamber. ### Claim 2 (depends on 1) The liquid ejection head according to claim 1, wherein the number of stages in the expansion potential difference change is equal to the number of stages in the contraction potential difference change. ### Claim 3 (depends on 1) The liquid ejection head according to claim 1, wherein the magnitude of the expansion potential difference change is equal to the magnitude of the contraction potential difference change. ### Claim 4 (depends on 1) The liquid ejection head according to claim 1, wherein the stages are equal voltage increments in magnitude. ### Claim 5 (depends on 1) The liquid ejection head according to claim 1, wherein the number of stages in the expansion potential difference change is two, and the number of stages in the contraction potential difference change is two. ### Claim 6 (depends on 1) The liquid ejection head according to claim 1, wherein the number of stages in the expansion potential difference change is three, and the number of stages in the contraction potential difference change is three. ### Claim 7 (depends on 1) The liquid ejection head according to claim 1, wherein when the period of the acoustic resonance frequency is λn and the number of stages in each of the expansion and contraction potential difference changes is h, an i-th stage is any one of the h stages, and a j-th stage is another one of the h stages after the i-th stage, then the time interval Tij between the i-th potential difference change start time and the j-th potential difference change start time satisfies the relationship: (k/2−1/6)λn≤Tij≤(k/2+1/6) λn, when k is an odd number of 1 or more. ### Claim 8 (depends on 7) The liquid ejection head according to claim 7, wherein the time interval Tij satisfies the relationship: (k/2−1/6)λn≤Tij≤kλn/2. ### Claim 9 (depends on 1) The liquid ejection head according to claim 1, wherein the acoustic resonance frequency is an odd multiple of approximately three times or more of the main acoustic resonance frequency. ### Claim 10 (depends on 1) The liquid ejection head according to claim 1, wherein the drive circuit includes a switching circuit connecting electrodes of the actuator to a voltage source and generates the drive signal by switching of the switching circuit. ### Claim 11 A liquid ejection apparatus, comprising: an actuator configured to vary the volume of a pressure chamber according to drive signals applied thereto; and a drive circuit configured to supply drive signals for driving the actuator, wherein the drive circuit generates a drive signal including an ejection waveform for the actuator with an expansion potential difference change that changes in stages and a contraction potential difference change that changes in stages, and sets the timing of the stages to cancels the vibration of an acoustic resonance frequency in a frequency range higher than a main acoustic resonance frequency of a liquid in the pressure chamber. ### Claim 12 (depends on 11) The liquid ejection apparatus according to claim 11, wherein the number of stages in the expansion potential difference change is equal to the number of stages in the contraction potential difference change. ### Claim 13 (depends on 11) The liquid ejection apparatus according to claim 11, wherein the magnitude of the expansion potential difference change is equal to the magnitude of the contraction potential difference change. ### Claim 14 (depends on 11) The liquid ejection apparatus according to claim 11, wherein the stages are equal voltage increments in magnitude. ### Claim 15 (depends on 11) The liquid ejection apparatus according to claim 11, wherein the number of stages in the expansion potential difference change is two, and the number of stages in the contraction potential difference change is two. ### Claim 16 (depends on 11) The liquid ejection apparatus according to claim 11, wherein the number of stages in the expansion potential difference change is three, and the number of stages in the contraction potential difference change is three. ### Claim 17 (depends on 11) The liquid ejection apparatus according to claim 11, wherein when the period of the acoustic resonance frequency is λn and the number of stages in each of the expansion and contraction potential difference changes is h, an i-th stage is any one of the h stages, and a j-th stage is another one of the h stages after the i-th stage, then the time interval Tij between the i-th potential difference change start time and the j-th potential difference change start time satisfies the relationship: (k/2−1/6)λn≤Tij≤(k/2+1/6) λn, when k is an odd number of 1 or more. ### Claim 18 (depends on 17) The liquid ejection apparatus according to claim 17, wherein the time interval Tij satisfies the relationship: (k/2−1/6)λn≤Tij≤kλn/2. ### Claim 19 (depends on 11) The liquid ejection apparatus according to claim 11, wherein the acoustic resonance frequency is an odd multiple of approximately three times or more of the main acoustic resonance frequency. ### Claim 20 (depends on 11) The liquid ejection apparatus according to claim 11, wherein the drive circuit includes a switching circuit connecting electrodes of the actuator to a voltage source and generates the drive signal by switching of the switching circuit.