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JP-2026076092-A - Droplet discharge device

JP2026076092AJP 2026076092 AJP2026076092 AJP 2026076092AJP-2026076092-A

Abstract

[Problem] To provide a droplet dispensing device that can suppress misjudgments in the detection process of dispensing defects. [Solution] The droplet dispensing device includes a control device that performs the following steps: detecting noise based on a first signal output from a light receiving unit based on light emitted from a light source before detecting whether there is a nozzle dispensing defect; determining the amount of noise to be subtracted based on a first spectrum relating to the first signal, which shows the relationship between signal intensity and frequency, before detecting whether there is a nozzle dispensing defect; obtaining a second spectrum relating to a second signal output from a light receiving unit based on light emitted from a light source when droplets are dispensed by the nozzle; subtracting the determined amount of subtraction from the second spectrum; and detecting whether there is a nozzle dispensing defect based on the second spectrum after the subtraction. [Selection Diagram] Figure 6

Inventors

  • 伊藤 敦
  • 加藤 雄哉
  • 高山 治久

Assignees

  • ブラザー工業株式会社

Dates

Publication Date
20260511
Application Date
20250123
Priority Date
20241023

Claims (13)

  1. A dispensing head having multiple nozzles for dispensing droplets onto the printing medium, A light source that emits light toward the flight space in which the droplet ejected from the nozzle is flying, A light receiving unit that detects the amount of light received after the light emitted from the light source has passed through the flight space and outputs a signal, A control device is provided, The control device is Before detecting whether or not there is a nozzle discharge defect, a process is performed to detect noise based on a first signal output from the light receiving unit based on the light emitted from the light source, Before detecting whether or not there is a nozzle discharge defect, a process is performed to determine the amount of noise to be subtracted based on the first spectrum relating to the first signal, which shows the relationship between signal intensity and frequency. A process to obtain a second spectrum relating to a second signal output from the light receiving unit based on the light emitted from the light source when the droplet is ejected by the nozzle, A process of subtracting the determined subtraction amount from the second spectrum, A droplet dispensing device that performs a process to detect whether or not there is a nozzle dispensing defect based on the second spectrum after subtraction.
  2. The droplet dispensing apparatus according to claim 1, wherein the control device performs a Fast Fourier Transform on the first signal to obtain a first FFT spectrum as the first spectrum, and determines the first FFT spectrum as the subtraction amount.
  3. The droplet dispensing apparatus according to claim 1, wherein the control device performs a Fast Fourier Transform on the first signal to obtain a first FFT spectrum as the first spectrum, and determines a predetermined constant value obtained from the first FFT spectrum as the subtraction amount.
  4. The control device is The process of performing a Fast Fourier Transform on the first signal to obtain a first FFT spectrum as the first spectrum is performed, and the process of performing a Fast Fourier Transform on the second signal to obtain a second FFT spectrum as the second spectrum is performed. A reference value obtained from the first FFT spectrum for each frequency region is determined as the subtraction amount for each frequency region. The droplet dispensing device according to claim 1, wherein each of the subtraction amounts determined for each frequency region is subtracted from each portion of the second FFT spectrum corresponding to each of the frequency regions.
  5. In the process of detecting the noise, the control device, A process of ejecting the liquid droplet from the nozzle at a position where it does not intersect with the light emitted from the light source, A droplet dispensing device according to claim 1, which performs a process of detecting noise based on the first signal output from the light receiving unit based on the light emitted from the light source.
  6. The control device is A process to obtain the subtraction amount based on the first FFT spectrum, which is the first spectrum obtained by performing a fast Fourier transform on a portion of the first signal output from the light receiving unit within a predetermined frequency range, The process involves performing a Fast Fourier Transform on the second signal to obtain a second FFT spectrum as the second spectrum, The droplet dispensing device according to claim 1, which performs a process of subtracting the subtraction amount from the portion of the second FFT spectrum corresponding to the predetermined frequency range.
  7. The droplet dispensing device according to claim 6, wherein the control device obtains a frequency within a predetermined range based on the diameter of the light, the velocity of the droplets ejected from the nozzle, the droplet dispensing interval, and the number of droplets ejected.
  8. A dispensing head having multiple nozzles for dispensing droplets onto the printing medium, A light source that emits light toward the flight space in which the droplet ejected from the nozzle is flying, A light receiving unit that detects the amount of light received after the light emitted from the light source has passed through the flight space when the droplet is ejected by the nozzle, and outputs a detection signal. A control device is provided, The control device is A process of discharging the liquid droplet from the nozzle, The process of receiving the detection signal corresponding to the ejected droplet from the light receiving unit, A process to obtain the number of peak waveforms in the detection signal whose maximum amplitude is greater than or equal to a threshold, A process to identify a target peak waveform, which is one of the peak waveforms to be targeted, based on the number of peak waveforms, A process to obtain the timing of the appearance of the peak in the target peak waveform, A droplet dispensing device that performs a process to determine whether or not there is a nozzle dispensing defect based on a comparison between the voltage of the peak based on the timing of appearance and the voltage of a reference peak in a predetermined reference waveform.
  9. The droplet dispensing apparatus according to claim 8, wherein the control device, when comparing the peak voltage with the reference peak voltage, obtains a voltage difference which is the difference between the peak voltage and the maximum voltage in the target peak waveform, and the difference between the reference peak voltage and the maximum voltage in the reference waveform.
  10. The aforementioned peak waveform includes a first peak waveform corresponding to a large droplet and a second peak waveform corresponding to a small droplet. The droplet dispensing device according to claim 8, wherein the control device acquires the timing of the appearance of the maximum amplitude in the first peak waveform as the timing of the appearance of the peak.
  11. The aforementioned peak waveform includes a first peak waveform corresponding to a large droplet and a second peak waveform corresponding to a small droplet. The droplet dispensing device according to claim 8, wherein the control device acquires the timing at which the derivative of the voltage value in the first peak waveform becomes zero as the timing of the appearance of the peak.
  12. The aforementioned peak waveform includes a first peak waveform corresponding to a large droplet and a second peak waveform corresponding to a small droplet. The droplet dispensing device according to claim 8, wherein the control device uses the voltage value corresponding to the amount of light received when the droplet is not being dispensed as the reference for integration, acquires a decreasing region which is the portion of the integrated waveform with respect to the voltage value in the first peak waveform in which the integrated value decreases, and acquires the appearance timing on the first peak waveform corresponding to the midpoint of the integrated values before and after the decreasing region as the appearance timing of the peak.
  13. The aforementioned peak waveform includes a first peak waveform corresponding to a large droplet and a second peak waveform corresponding to a small droplet. The droplet dispensing device according to claim 8, wherein the control device acquires a slope portion which is the portion where the approximate straight line of the integral waveform with respect to the voltage value in the first peak waveform is greater than or equal to a predetermined slope, and acquires the timing on the first peak waveform corresponding to the midpoint in the slope portion as the timing of the appearance of the peak.

Description

This disclosure relates to a droplet ejection device used in printing devices such as inkjet printers. Conventionally, a liquid dispensing failure detection device is known that comprises a dispensing head with a nozzle, a light-emitting element, and a light-receiving unit (Patent Document 1). The light-receiving unit includes a light-receiving element, a current-voltage conversion circuit, and a high-pass filter. The light-receiving element outputs a current corresponding to the intensity of the received light. The current-voltage conversion circuit converts the current output by the light-receiving element into a voltage and outputs it. The high-pass filter removes noise components from the voltage output by the current-voltage conversion circuit. For example, the high-pass filter removes the offset voltage that occurs when a liquid droplet does not pass through the beam. Furthermore, a liquid dispensing failure detection device is also known that detects dispensing failures using the average value of multiple peak values as a feature quantity of the waveform data acquired by the light-receiving unit (Patent Document 2). Japanese Patent Publication No. 2012-218258Japanese Patent Publication No. 2012-086478 This is a plan view showing a droplet dispensing device according to one embodiment of the present disclosure.Figure 1 is a cross-sectional view showing the configuration of the discharge head.This is a block diagram showing the components of a printing apparatus equipped with a droplet ejection device, as shown in Figure 1.This is a block diagram showing the functional configuration of the control device in Figure 3.This diagram shows how a laser beam is shone onto ink droplets being ejected from the ejection head while they are in flight.Figure 6A shows an example of the first FFT spectrum, Figure 6B shows an example of the second FFT spectrum, and Figure 6C shows an example of the second FFT spectrum after noise reduction.Figure 7A shows an example of the first FFT spectrum, Figure 7B shows an example of the second FFT spectrum, and Figure 7C shows an example of the second FFT spectrum after noise reduction.Figure 8A shows an example of the first FFT spectrum, Figure 8B shows an example of the second FFT spectrum, and Figure 8C shows an example of the second FFT spectrum after noise reduction.This diagram shows how ink droplets ejected from the ejection head pass through a laser beam.This table explains the frequency range of signals on which the Fast Fourier Transform (FFT) should be performed by the FFT unit.Figure 11A shows a configuration in which ink droplets are ejected from a nozzle at a position where they do not intersect with the laser beam emitted from the light source, and Figure 11B shows a configuration in which ink droplets are ejected from a nozzle at a position where they intersect with the laser beam emitted from the light source.This is a block diagram showing the functional configuration of a control device in one embodiment of the present disclosure.This figure shows the detection waveform when small droplets are separated from a large droplet that has been dispensed.Figure 14A shows the peak waveform of the detected waveform, and Figure 14B shows the integrated waveform of the detected waveform in Figure 14A.This diagram illustrates the minimum voltage value in the peak waveform.This figure shows the derivative waveform of the peak waveform.This figure shows the integral waveform of the peak waveform.Figure 18A shows the detected waveform, and Figure 18B shows the integrated waveform of the detected waveform in Figure 18A.This diagram illustrates the comparison process between the peak voltage in the averaged waveform obtained from the detected waveform and the reference peak voltage in the reference waveform.Figures 20A to 20C illustrate the process of obtaining an averaged waveform from multiple detected waveforms.Figures 21A to 21E illustrate an example of a process for identifying the timing of peak appearance. The droplet dispensing apparatus according to the embodiments of this disclosure will be described below with reference to the drawings. The droplet dispensing apparatus described below is merely one embodiment of this disclosure. Therefore, this disclosure is not limited to the following embodiments, and additions, deletions, and modifications are permitted without departing from the spirit of this disclosure. (First Embodiment) Figure 1 is a perspective view showing a droplet ejection device 100 according to one embodiment of the present disclosure. Figure 2 is a cross-sectional view showing the configuration of the ejection head 10 of Figure 1. Figure 3 is a block diagram showing the components of a printing apparatus 1 equipped with the droplet ejection device 100 of Figure 1. Figure 4 is a block diagram showing the functional configuration of the control device 20 of Figure 3. In Figures 1 and 2, mutually orthogonal directions are referred to as the first directi