JP-7855286-B1 - printing device

JP7855286B1JP 7855286 B1JP7855286 B1JP 7855286B1JP-7855286-B1

Abstract

[Problem] Maintain the piezoelectric voltage at an appropriate value while the image printing process is underway. [Solution] In a continuous inkjet printer 5, when an electric field is generated by the deflection electrode 15, when the piezoelectric voltage VA is changed from a first voltage value VA1, it is determined whether the maximum value at detection time t has moved to the high voltage side or the low voltage side of the piezoelectric voltage VA based on the change in the amount of charge of ink droplets ID corresponding to the change in the timing of the application of the charging voltage, and the piezoelectric voltage VA is brought closer to the second voltage value which is the destination of the maximum value at detection time t. [Selection Diagram] Figure 2

Inventors

野下祐介
奥谷将之
寺西佑介

Assignees

紀州技研工業株式会社

Dates

Publication Date: 20260508
Application Date: 20251202

Claims (2)

A printing apparatus that ejects ink onto an object and prints an image onto the object, The ink nozzle that ejects the aforementioned ink, A piezoelectric element that applies vibrations of a frequency corresponding to the applied piezoelectric voltage to the ink ejected from the ink nozzle, thereby separating the ink into a plurality of consecutive ink droplets, A charging electrode that charges the ink droplet by applying a charging voltage, A deflection electrode that generates an electric field in a predetermined direction and deflects the direction of movement of the ink droplet charged by the charging electrode, A detection electrode for detecting the amount of charge of the aforementioned ink droplet, The system comprises the ink nozzle, the piezoelectric element, the charging electrode, and the deflection electrode, and a control unit for controlling them. The control unit, A piezoelectric voltage setting unit sets the piezoelectric voltage to a first voltage value corresponding to the maximum value of the detection time, based on the correlation between the detection time from when the charging voltage is applied to the charging electrode until the amount of charge of the ink droplet is detected by the detection electrode and the piezoelectric voltage. A charging setting unit that sets the timing for applying the charging voltage to the charging electrode, The system includes an adjustment unit that adjusts the piezoelectric voltage to a value other than the first voltage value based on the amount of charge detected by the detection electrode, In a state in which the electric field is generated by the deflection electrode, the adjustment unit, when the piezoelectric voltage is changed, determines whether the maximum value of the detection time has moved to the high voltage side or the low voltage side of the piezoelectric voltage based on the change in the amount of charge corresponding to the change in the application timing by the charge setting unit, and adjusts the piezoelectric voltage to approach the second voltage value which is the destination of the maximum value of the detection time.
The aforementioned piezoelectric voltage is an AC voltage. The printing apparatus according to claim 1, wherein the application period of the charging voltage is shorter than one cycle of the piezoelectric voltage.

Description

This invention relates to a printing apparatus. To manage the manufacturing date, production lot number, and expiration date (best before date, use-by date) of products, this information is printed directly on the product or on the packaging container during the manufacturing and logistics lines. In recent years, inkjet printers (hereinafter abbreviated as "IJP") have become popular as a printing method because they are ideal for printing text that changes constantly, such as dates and lot numbers. In particular, in continuous inkjet printers (IJPs) that form characters and other shapes by changing the direction of movement of ink droplets generated and continuously ejected by an oscillator such as a piezoelectric element using a deflection electrode, it is necessary to adjust the excitation voltage applied to the piezoelectric element to an appropriate value in order to generate ink droplets with the correct droplet shape, in order to improve print quality. A known method for setting the excitation voltage value to an appropriate value involves sweeping the excitation voltage value while the deflection electrode is not energized, dividing one period of the excitation voltage applied to the piezoelectric element into multiple phases, and synchronizing the timing of the charging voltage application with the divided phases. Based on the correspondence between the excitation voltage application timing (printing phase) obtained by this synchronization with the amount of charge applied to the ink droplet, a printing phase that allows for normal charging is identified for each excitation voltage value, and the excitation voltage value immediately after the direction of increase or decrease of the printing phase value reverses from increasing to decreasing is considered the appropriate value (for example, Patent Document 1). Japanese Patent Publication No. 2023-25327 This figure shows the configuration of a printing system according to one embodiment of the present invention.This is a functional block diagram of a printing device used in a printing system.This is a schematic diagram showing the configuration of the print head.This figure shows an example of the correlation between detection time and piezoelectric voltage.This figure shows an example of the relationship between the timing of applying the charging voltage and the amount of charge on an ink droplet.This figure shows the relationship between changes in piezoelectric voltage characteristics and changes in charge information associated with changes in piezoelectric voltage.This is a flowchart showing a piezoelectric voltage adjustment method according to one embodiment of the present invention. A printing apparatus according to one embodiment of the present invention will be described below with reference to the drawings. However, the present invention is not limited to the following embodiment. Figure 1 shows the configuration of a printing system 1 according to one embodiment of the present invention. Figure 2 is a functional block diagram of the inkjet printer (IJP) 5 used in the printing system 1. The IJP 5 is an example of a printing device. The printing system 1 prints an image on the side surface (printing surface) 31 of a workpiece 3 transported by the conveyor C, using the IJP 5 installed adjacent to the conveyor C. The workpiece 3 is an example of an object. As shown in Figures 1 and 2, the IJP5 comprises a controller unit 51, a print head 55, and a photoelectric sensor 57. The print head 55 ejects ink onto the workpiece 3 to print an image on it. The photoelectric sensor 57 is installed, for example, near the conveyor C upstream of the print head 55, as shown in Figure 1, and generates a signal when the workpiece 3 passes in front of the photoelectric sensor 57. The output signal from the photoelectric sensor 57 is input to the controller unit 51 and used as a trigger signal when generating a timing signal. Based on this signal, the position at which printing begins on the print surface 31 is determined. The controller unit 51 controls the operation of the print head 55. Specifically, the controller unit 51 includes a control unit 52, an operation unit 53, a display 54, and a storage unit 56. The operation unit 53 and the display 54 are composed of, for example, a touch-panel type liquid crystal display. The operation unit 53 accepts user input. The display 54 is used to display the print content, etc., to be printed on the print surface 31 of the workpiece 3. Note that the operation unit 53 and the display 54 are not limited to a touch-panel type liquid crystal display; they may each be independent operation switches and various types of displays. The control unit 52 includes a processor such as a CPU (Central Processing Unit), and by reading and executing a program stored in the memory unit 56 (described later), it generates drive signals and timing signals for controlling the print head 55 according to the operations input to the operation