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EP-4245422-B1 - LIQUID DISCHARGE APPARATUS, LIQUID DISCHARGE METHOD, AND CARRIER MEDIUM

EP4245422B1EP 4245422 B1EP4245422 B1EP 4245422B1EP-4245422-B1

Inventors

  • OMURA, TAITO

Dates

Publication Date
20260506
Application Date
20230314

Claims (8)

  1. A liquid discharge apparatus (200) comprising: a liquid discharge head (10) having a nozzle hole (N) from which a liquid (3) is discharged, the liquid discharge head (10) including: a valve (12) configured to open and close the nozzle hole (N); and a valve driver (13) configured to drive the valve (12); and a circuitry (500) configured to: cause the valve driver (13) to drive the valve (12) to open the nozzle hole (N) for a valve opening time to discharge the liquid (3) onto an object (3000); and change the valve opening time based on a head pressure applied to the liquid (3) in the liquid discharge head (10), the liquid discharge apparatus (200) being characterized in that the circuitry (500) is further configured to shorten a switching interval of the valve (12) to open and close the nozzle hole (N) if a change rate of the head pressure over time increases.
  2. The liquid discharge apparatus (200) according to claim 1, wherein the circuitry (500) is further configured to increase the valve opening time if the head pressure decreases.
  3. The liquid discharge apparatus (200) according to claim 1, wherein the circuitry (500) is further configured to: cause the valve driver (13) to drive the valve (12) to open the nozzle hole (N) for a first valve opening time to discharge the liquid (3) onto a first area of the object (3000) at a first pressure of the head pressure; and cause the valve driver (13) to drive the valve (12) to open the nozzle hole (N) for a second valve opening time longer than the first valve opening time to discharge the liquid (3) onto a second area of the object (3000) at a second pressure lower than the first pressure of the head pressure.
  4. The liquid discharge apparatus (200) according to claim 1 or 3, wherein the circuitry (500) is further configured to: apply a drive waveform having a voltage duty to the valve driver (13) to drive the valve (12); and change the voltage duty to change the valve opening time.
  5. A liquid discharge method comprising: driving a valve (12) to open and close a nozzle hole (N) for a valve opening time to discharge a liquid (3) onto an object (3000); and changing the valve opening time based on a head pressure applied to the liquid (3) to be discharged from the nozzle hole (N), the liquid discharge method being characterized by shortening a switching interval of the valve (12) to open and close the nozzle hole (N) if a change rate of the head pressure over time increases.
  6. The liquid discharge method according to claim 5, wherein the changing increases the valve opening time if the head pressure decreases.
  7. A carrier medium carrying computer readable code for controlling a liquid discharge apparatus to carry out a method, comprising: controlling a valve opening time of a valve (12) configured to open and close a nozzle hole (N) to discharge a liquid (3) onto an object (3000); and changing the valve opening time based on a head pressure applied to the liquid (3) to be discharged from the nozzle hole (N), the computer readable code being characterized in that it further comprises shortening a switching interval of the valve (12) to open and close the nozzle hole (N) if a change rate of the head pressure over time increases.
  8. The carrier medium according to claim 7, wherein the changing increases the valve opening time if the head pressure decreases.

Description

BACKGROUND Technical Field Embodiments of the present disclosure relate to a liquid discharge apparatus, a liquid discharge method, and a carrier medium carrying computer readable code. Related Art In the related art, a liquid discharge apparatus includes a discharge head that discharges a liquid and applies the liquid to an object. Such a liquid discharge apparatus is used for various applications such as coating of the object and image formation on a recording medium. For example, Japanese Patent No. 4123897 discloses a liquid discharge apparatus that has a nozzle hole from which a liquid such as ink is discharged and includes an ink chamber to supply pressurized liquid (ink) to the nozzle hole, a needle valve disposed in the ink chamber to open and close the nozzle hole, and a driver to drive the needle valve. However, with the configuration described in Japanese Patent No. 4123897, a discharge amount of the liquid discharged from the discharge head decreases immediately after the start of discharge of the liquid or when the number of the nozzle holes from which the liquid is discharged is changed. As a result, a liquid application quality (coating quality) of the liquid discharge apparatus to the object may deteriorate. EP 0 480 080 A1 discloses a coating apparatus having a valve disposed in a paint supply path extended from a coating supply source to a coating machine for controlling the flow rate of a paint in accordance with the amount of a paint discharged from the coating machine. SUMMARY An object of the present disclosure is to provide a liquid discharge apparatus that prevents the liquid application quality to an object from deteriorating. Embodiments of the present disclosure describe an improved liquid discharge apparatus that includes a liquid discharge head and circuitry. The liquid discharge head has a nozzle hole from which a liquid is discharged and includes a valve to open and close the nozzle hole and a valve driver to drive the valve. The circuitry causes the valve driver to drive the valve to open the nozzle hole for a valve opening time to discharge the liquid onto an object, and changes the valve opening time based on a head pressure applied to the liquid in the liquid discharge head. According to other embodiments of the present disclosure, there are provided a liquid discharge method and a carrier medium carrying computer readable code for controlling a computer system to carry out the liquid discharge method. The method includes driving a valve to open and close the nozzle hole for a valve opening time to discharge a liquid onto an object, and changing the valve opening time based on a head pressure applied to the liquid to be discharged from the nozzle hole. As a result, according to an embodiment of the present disclosure, a liquid application quality to the object can be enhanced. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS A more complete appreciation of the disclosure and many of the attendant advantages and features thereof can be readily obtained and understood from the following detailed description with reference to the accompanying drawings, wherein: FIG. 1 is a schematic view of a coating robot including a liquid discharge apparatus according to an embodiment of the present disclosure;FIG. 2 is a schematic view of the liquid discharge apparatus according to the present embodiment;FIG. 3 is a schematic perspective view of a discharge head of the liquid discharge apparatus according to the present embodiment;FIG. 4 is a block diagram illustrating a hardware configuration of the liquid discharge apparatus according to the present embodiment;FIG. 5 is a functional block diagram of the liquid discharge apparatus according to the present embodiment;FIG. 6 is a graph illustrating a change in a liquid pressure in the discharge head over time;FIG. 7 is a graph illustrating a change in a discharge amount of liquid discharged from the discharge head over time;FIG. 8 is a graph illustrating the change in the liquid pressure in the discharge head, illustrating a difference depending on the number of nozzles to be driven;FIG. 9 is a diagram illustrating an example of a drive waveform applied to the discharge head;FIG. 10 is a graph illustrating a relation between a valve opening time and the discharge amount;FIG. 11 is graphs illustrating an example of the liquid pressure in the discharge head, the valve opening time, and the discharge amount; andFIG. 12 is graphs illustrating another example of the liquid pressure in the discharge head, the valve opening time, and the discharge amount. The accompanying drawings are intended to depict embodiments of the present invention and should not be interpreted to limit the scope thereof. The accompanying drawings are not to be considered as drawn to scale unless explicitly noted. Also, identical or similar reference numerals designate identical or similar components throughout the several views. DETAILED DESCRIPTION In describing e