Inkjet recording device

Abstract

To provide an ink jet recording device which can detect an abnormality in an early stage.SOLUTION: An ink jet recording device includes: a printing head which receives supply of ink and performs printing; and a body which includes a control device and supplies ink to the printing head. The control device performs an automatic phase gain adjustment to adjust an automatic phase gain value of an amplifier circuit so as to adjust a maximum voltage of a waveform of an automatic phase signal for detecting a timing of applying a charge voltage for ink particles, for an abnormality determination during a period from ink injection to entering a standby state.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an inkjet recording apparatus. [Background Art]

[0002] An inkjet recording apparatus may be used continuously for a long period of time. In this case, in order to adjust the inkjet recording apparatus to a state where correct printing can be performed, it is important to confirm normal values through manual adjustment / operation check such as excitation adjustment and auto phase gain adjustment by operating an operation screen before incorrect printing results occur. When abnormal values are recorded in processes such as excitation adjustment and auto phase gain adjustment, various factors can be considered, such as deterioration of the used ink, contamination around the gutter section in the print head caused by ink or intensifying liquid, and failure of the substrate.

[0003] As a prior art related to the present invention, there is Patent Document 1. Patent Document 1 describes an inkjet recording apparatus that can easily identify the cause of ink deterioration by displaying a waveform result of the charging efficiency of ink particles on an operation panel screen. In the inkjet recording apparatus of Patent Document 1, a phase detection signal in the form of an analog signal output from a sensor, in which a voltage corresponding to the charge amount of ink particles charged by a charging voltage for phase search is induced, is converted into a digital signal by an A / D converter, stored and saved in a memory, and the result of waveform processing of the charging efficiency of ink particles is displayed on a display device such as an operation panel. The inkjet recording apparatus of Patent Document 1 can easily identify the cause of ink deterioration by displaying the waveform result of the charging efficiency of ink particles on the operation panel screen. [Prior Art Literature] [Patent Literature]

[0004] [Patent Document 1] Japanese Unexamined Patent Publication No. 2013-10229 [Summary of the Invention] [Problem to be Solved by the Invention]

[0005] Inkjet recording devices undergo adjustments and operational checks via screen operation, for example, during installation, factory shipment, circuit board replacement, or inspection by a service technician. These adjustments and operational checks performed by a service technician via screen operation include excitation adjustment, which adjusts the excitation voltage necessary for generating ink particles; auto-phase gain adjustment, which adjusts the maximum voltage of the auto-phase waveform used to apply the charging voltage to the ink particles; charging voltage confirmation, which verifies that the voltage for charging the ink particles is output from the circuit board; and phase margin testing, which checks whether there is sufficient phase margin by changing the phase at which the ink particles are charged and verifying the print output. Auto-phase gain adjustment involves adjusting the gain of the amplification circuit to adjust the maximum voltage of the auto-phase waveform used to detect the timing of applying the charging voltage to the ink particles.

[0006] When ink particles are in poor condition due to ink degradation or when droplets of ink particles colliding with the material being printed come into contact with the print head, if printing is performed for a long period of time without performing adjustments / operation checks such as excitation adjustment or auto-phase gain adjustment before printing, ink and supplemental fluid gradually adhere to and accumulate on the orifice, charged electrode, positive deflection electrode, negative deflection electrode, gutter, or head tip surface within the print head, causing a deterioration in print quality. Therefore, there is a need for an inkjet recording device that can detect such abnormal conditions (abnormalities) that cause deterioration in print quality at an early stage.

[0007] This invention was made to solve the above problems. Specifically, one of the objectives of this invention is to provide an inkjet recording device that can detect abnormalities at an early stage. [Means for solving the problem]

[0008] To solve the above problems, the inkjet recording apparatus comprises a print head that receives ink and performs printing, and a control device and a main body that supplies the ink to the print head, wherein the print head has a piezoelectric element for converting the ink into ink particles, a charging electrode for charging the ink particles, a deflection electrode for deflecting the charged ink particles, and an autophase sensor that induces a voltage corresponding to the amount of charge of the ink particles, and the main body has an amplification circuit that amplifies and outputs the autophase signal output from the autophase sensor, wherein the control device is configured to perform autophase gain adjustment, which adjusts the autophase gain value of the amplification circuit to adjust the maximum voltage of the waveform of the autophase signal for detecting the timing of applying the charging voltage to the ink particles for abnormality detection, after ink ejection has started and before the state of the inkjet recording apparatus enters a standby state. [Effects of the Invention]

[0009] According to the present invention, abnormalities can be detected at an early stage. The effects described herein are not necessarily limited, and any of the effects described in this disclosure may be present. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a block diagram showing the configuration of an inkjet recording device. [Figure 2] Figure 2 shows examples of various ink particle shapes formed by the voltage of the electrostrictive element in the print head. [Figure 3] Figure 3 is a diagram illustrating the charging signal used for phase search. [Figure 4] Figure 4 shows an example of an autophase signal waveform. [Figure 5A] Figure 5A is a diagram illustrating the case where the detection result of the autophase signal is abnormal. [Figure 5B] Figure 5B is a diagram illustrating the case where the detection result of the autophase signal is abnormal. [Figure 6] Figure 6 is a flowchart illustrating the operation of an inkjet recording device. [Modes for carrying out the invention]

[0011] Embodiments of the present invention will be described below with reference to the drawings. In all drawings of the embodiments, the same or corresponding parts may be denoted by the same reference numerals.

[0012] <<Embodiment>> Embodiments of the present invention will be described below with reference to the drawings. Figure 1 is a block diagram showing the configuration of an inkjet recording apparatus according to an embodiment of the present invention.

[0013] As shown in Figure 1, the inkjet recording device comprises an inkjet recording device body 100 and a print head 200. The print head 200 is installed facing the transport track of the object to be printed 400, which is transported by a conveyor 300 of the production line.

[0014] In the inkjet recording device body 100, the MPU 101 is a microprocessing unit (hereinafter referred to as MPU) that controls the entire inkjet recording device. The MPU 101 is an example of a control device and may also be referred to as a "control device" for convenience. The ROM 102 is a read-only memory that stores the control program and data necessary for the operation of the MPU 101. The RAM 103 is a rewritable memory that temporarily stores data required by the MPU 101 during program execution.

[0015] Furthermore, the inkjet recording device includes an input panel 104 for inputting print content and setting values, and a display device 105 for displaying the input data and print content. The input panel 104 and the display device 105 use a touch-input type display panel in which transparent touch switches are superimposed on the surface of a liquid crystal display screen. The bus line 106 (bus) transmits data signals, address signals, and control signals from the MPU 101.

[0016] The print head 200 ejects ink 109, which is supplied under pressure from an ink container 107 of an inkjet recording apparatus main body 100 by an ink supply pump 108, from a nozzle 201 in the form of an ink column 109a. An excitation voltage generation circuit 112 provided in the inkjet recording apparatus main body 100 applies an excitation signal to an electrostrictive element 202 of the nozzle 201 to vibrate the electrostrictive element at a constant period. Thereby, the ink column 109a is formed into ink particles 109b. The electrostrictive element 202 is also referred to as a "piezoelectric element".

[0017] The print head 200 includes a charging electrode 203 disposed so as to surround a position where the ink column 109a becomes the ink particles 109b. When regularly generated ink particles (ink droplets) 109b are separated from the ink column 109a, electric charges are imparted to the ink particles 109b by a voltage of the charging electrode 203.

[0018] The print head 200 includes a deflection electrode 204 that generates a deflection electric field for deflecting charged and flying ink particles 109b in accordance with the amount of charge, directing the ink particles to a printing medium 400 and performing printing. The print head 200 also includes a gutter 205 that captures ink particles 109b not used for printing, and an auto-phase sensor 206 that is a phase detection sensor generating a phase detection signal corresponding to the charge amount of the ink particles 109b captured by the gutter 205.

[0019] The inkjet recording apparatus main body 100 further includes a pump drive circuit 111 that controls the ink supply pump 108 and an ink recovery pump 110 that recovers the ink particles 109b captured by the gutter 205 into the ink container 107.

[0020] The inkjet recording apparatus main body 100 includes an excitation voltage generation circuit 112 for generating an excitation signal to excite the electrostrictive element 202 built in the print nozzle 201, so as to impart regularity to the timing at which the ink column 109a ejected from the print nozzle 201 is separated into the ink particles 109b.

[0021] Furthermore, the inkjet recording device body 100 includes a D / A converter 115 that converts the digital signal-type charge signals output from the printing charge signal generation circuit 113 and the phase search charge signal generation circuit 114 into analog voltage signals, and an amplification circuit 116 that amplifies the analog voltage signal output from the D / A converter 115 to generate a charge voltage to be applied to the charge electrode 203.

[0022] Furthermore, the inkjet recording device body 100 includes a deflection voltage generation circuit 117 that generates a deflection voltage to be applied to the deflection electrode 204, an amplification circuit 118 that amplifies the phase detection signal in analog signal form output from the auto phase sensor 206, a phase determination circuit 119 that receives the amplified phase detection signal and determines whether the charge is good or bad, and an A / D converter 120 that receives the amplified phase detection signal and performs A / D conversion.

[0023] In the inkjet recording device configured in this way, the MPU 101 controls the pump drive circuit 111 via the bus line 106 to operate the ink supply pump 108 and the ink recovery pump 110, thereby sucking up and pressurizing the ink 109 in the ink container 107 and supplying it to the print nozzle 201, causing the ink column 109a to be ejected from the print nozzle 201 in a columnar shape and separated into ink particles 109b. In order to deflect the ink particles 109b to a predetermined position, the printing charge signal generation circuit 113 generates a charge signal and applies a charge voltage to the charge electrode 203 according to the signal. The charged ink particles 109b pass through the deflection electrode 204 and adhere to a predetermined position on the object to be printed 400. The uncharged ink particles 109b are collected in the gutter 205. The inkjet recording device sucks up the ink particles 109b captured in the gutter 205 and collects them in the ink container 107.

[0024] An inkjet recording device requires an excitation signal, a charging signal, an automatic phase signal (also called an "auto-phase signal" or "phase detection signal"), and a deflection voltage to operate. Among these, the auto-phase signal controls the timing of ink particles by monitoring the charging state in response to changes in ink viscosity due to changes in ambient temperature, changes in physical properties due to ink degradation, and pressure changes due to vibrations from outside the inkjet recording device (print head and head cable), and detecting the optimal charging timing.

[0025] Figure 2 shows examples of the shapes of ink particles 109b formed by the voltage of the electrostrictive element 202 in the print head 200. The electrostrictive element 202 in the print nozzle 201 is subjected to mechanical vibration in the direction in which the ink column 109a is ejected. Due to the force of the vibration, the body 130 of the ink becomes rounded, the constricted portion 131 becomes thinner, and it eventually becomes an ink particle 109b. A voltage is applied to the electrostrictive element 202 according to the signal from the excitation voltage generation circuit 112. Due to the influence of pressure, temperature, changes in the ink material, etc., the timing of the cutting point of the ink column 109a may change, and the shape of the ink particles may also change. In order to perform high-quality printing, in addition to a normal ink particle formation state, it is necessary to apply a charging signal to the charging electrode 203 at the correct timing. In order to reliably charge the ink particles 109b, the inkjet recording device needs to accurately know the phase in which the current ink particles 109b are being generated. Based on the result of detecting this phase, the timing of applying the charging signal to the charging electrode 203 is adjusted to charge the ink particles 109b.

[0026] Figure 3 is a diagram illustrating the charging signal for phase search. According to the charging signal of the phase search charging signal generation circuit 114 in the inkjet recording device body 100, a phase search charging voltage is generated with a changed phase, by dividing one period of the excitation signal into 16 equal parts (this division is expressed as an electrical angle = phase, from phase 0 to F). This is repeated 16 times up to phase F. Each phase takes 10 [ms], and performing this for 16 phases takes 160 [ms], so the detection time for one auto-phase is defined as the auto-phase detection period. The charging signal is applied 30 times consecutively in phase 0 to charge the ink particles 109b. This is done for one period from phase 0 to phase F. The ink particles 109b charged with this phase search charging voltage are made to a size such that they do not jump over the gutter 205 (they can be captured by the gutter 205) The auto-phase signal output from the auto-phase sensor 206 is amplified by the amplification circuit 118 according to the amount of charge of the ink particles 109b charged with this phase-finding charging voltage, and input to the phase determination circuit 119.

[0027] The waveform of the autophase signal output from the amplification circuit 118 changes as shown in Figure 4 in accordance with the change in the generation phase of the phase-search charging voltage. The phase determination circuit 119 receives such autophase signals, compares the autophase signals of each input phase with a threshold value, binarizes them, and inputs them to the MPU 101. If the autophase signal is greater than the threshold value, it is set to "1", and if the autophase signal is less than the threshold value, it is set to "0". The MPU 101 determines that the phase obtained by subtracting 2 from the phase in which the binarized autophase signal changes from "1" to "0" is the optimal phase for generating the charging voltage that charges the ink particles 109b, and controls the printing charging signal to generate the printing charging voltage at that phase. This process is performed from ink ejection to the standby state, and is performed continuously while ink is ejecting.

[0028] Figures 5A and 5B show cases where the detection result of the auto-phase signal is abnormal. If the physical properties of the ink change due to ink degradation or other reasons, the ink particle formation state becomes abnormal, and the phase detection signal waveform changes as shown in Figure 5A. Figure 5B shows the case due to dirt inside the print head. The phase determination circuit 119 cannot search for the optimal phase because the auto-phase signal of each phase has a voltage lower than the threshold. In this state, the ink particles 109b cannot be charged properly, resulting in printing defects. In addition, the LED on the circuit board blinks according to the binarization result, repeatedly turning on and off in normal conditions, and remaining on or off without blinking in abnormal conditions.

[0029] Therefore, before printing, the operator can change the excitation voltage applied to the nozzle while observing the auto-phase signal waveform on the display device 105. If the waveform becomes abnormal and a message confirming ink degradation is displayed, the ink can be replaced, thereby preventing printing defects before production begins.

[0030] The inkjet recording apparatus according to this embodiment is configured to convert the auto-phase signals for each phase obtained in correspondence with the phase-search charging signals (charging voltages) for each phase in the phase search into digital signal-type phase detection data by the A / D converter 120, sample (acquire) them at appropriate intervals by the MPU 101 and store them in the RAM 103, and then read them from the RAM 103, process them into a waveform suitable for observation to identify the cause of printing defects, and display them on the display device 105. When the waveform of the auto-phase signal becomes abnormal while changing the excitation voltage applied to the nozzle, a message to confirm ink deterioration is displayed.

[0031] Next, an overview of the operation of the inkjet recording apparatus according to an embodiment of the present invention will be described with reference to the flowchart example in Figure 6. The inkjet recording apparatus starts operation from step 600, performs an appropriate process from among the processes described in steps 601 to 609 below, and then proceeds to step 610 to end this operation flow.

[0032] Step 601: The inkjet recording device unit 100 is turned on.

[0033] Step 602: When a specific operation is performed on the home screen (input panel 104) after startup, the MPU 101 controls the inkjet recording device to start ejecting ink.

[0034] Step 603: After the MPU 101 starts ink ejection, it automatically starts autophase gain adjustment. Autophase gain adjustment is the operation of adjusting the gain of the amplification circuit 118 to adjust the maximum voltage of the autophase waveform (autophase signal waveform) to (an appropriate voltage) for detecting the timing of applying the charging voltage to the ink particles 109b.

[0035] For example, the auto-phase gain adjustment adjusts the maximum voltage of the auto-phase waveform used to detect the timing of applying the charging voltage to the ink particles 109b. If at least one phase of the voltage detected from the APH sensor board (auto-phase sensor 206) with the ink particles 109b actually charged has a voltage of 7.5V or higher, the auto-phase gain value is lowered; otherwise, it is raised. Finally, if at least one phase of the acquired 16-phase APH voltage has a voltage of 2.5V or lower, the process is considered successful; otherwise, it is considered a failure. The auto-phase gain value is the gain value of the amplification circuit 118.

[0036] Step 604: MPU101 obtains the auto-phase gain value at a specific time (for example, when the auto-phase gain adjustment has been successfully completed).

[0037] Step 605: The MPU101 determines whether the auto-phase gain value is within a predetermined range. This determines whether the inkjet recording device is malfunctioning. If the auto-phase gain value is within the predetermined range, the inkjet recording device is likely to be functioning normally. Therefore, in this case, the MPU101 determines "YES" (determines it to be functioning normally) and proceeds to step 606. If the auto-phase gain value is outside the predetermined range, there is a possibility that the inkjet recording device is malfunctioning. Therefore, in this case, the MPU101 determines "NO" (determines it to be malfunctioning) and proceeds to step 608. The predetermined range is a range of auto-phase gain values ​​suitable for malfunction determination, and can be defined, for example, based on existing knowledge (data) or by conducting experiments.

[0038] Step 606: The MPU101 controls the inkjet recording device to enter a standby state. "Standby state" means that no deflection voltage is applied for printing, ink ejection and generation of ink particles 109b have been completed, and the appropriate voltage application timing (optimal charging timing) has been detected.

[0039] Step 607: The MPU101 controls the inkjet recording device to become printable, enabling printing. Note that "printable" means that "ink is being ejected and a deflection voltage is being applied."

[0040] Step 608: MPU101 controls the inkjet recording device to enter a warm-up state. The "warm-up state" is a state in which ink ejection and ink particle 109b generation are possible, but the appropriate voltage application timing (optimal charging timing) has not yet been detected.

[0041] Step 609: The MPU 101 displays a message indicating an abnormality on the inkjet recording device screen (display device 105). Examples of messages include, for example, "The ink being used may be degraded," "The inside of the print head may be dirty," or "There may be a malfunction in the circuit board." As shown in block BR1, the user (or service technician) who sees the message indicating an abnormality can resolve the cause of the abnormality by performing one of the following: ink replacement, cleaning, or circuit board replacement.

[0042] <Effects> As described above, the inkjet recording device according to the embodiment of the present invention automatically performs an auto-phase gain adjustment for abnormality detection when the power of the inkjet recording device is turned ON and ink ejection begins. If the auto-phase gain value of the auto-phase gain adjustment is outside a predetermined range, the inkjet recording device performs an action to notify the user (or service technician) of the abnormality before printing (such as displaying an abnormality message screen), thereby informing the user (or service technician) in advance and preventing deterioration of print quality.

[0043] <<Variation>> The present invention is not limited to the above embodiments, and various modifications can be adopted within the scope of the present invention. For example, in the above embodiments, abnormality determination was performed in two stages by determining either abnormal or normal based on the autophase gain value, but abnormality determination may be performed in three or more stages, such as normal, abnormal level 1, and abnormal level 2, based on the autophase gain value. In the above embodiments, the inkjet recording device may send a message indicating an abnormality to the user's (or service technician's) terminal via a network, and the message indicating an abnormality may be displayed on the display device of the user's (or service technician's) terminal. [Explanation of Symbols]

[0044] 100...Inkjet recording device main unit, 101...MPU, 102...ROM, 103...RAM, 104...Input panel, 105...Display device, 112...Excitation voltage generation circuit, 113...Charging signal generation circuit for printing, 114...Charging signal generation circuit for phase search, 119...Phase determination circuit, 200...Print head, 201...Print nozzle, 202...Electrostrictive element, 205...Gutter, 206...Auto phase sensor, 300...Conveyor

Claims

1. A print head that receives ink supply and performs printing, A control device is included, and the main body supplies the ink to the print head, Equipped with, The aforementioned print head is A piezoelectric element for converting the aforementioned ink into ink particles, A charging electrode for charging the ink particles, A deflection electrode that deflects the charged ink particles, An autophase sensor that induces a voltage corresponding to the charge amount of the ink particles, It has, The aforementioned main body is The system includes an amplification circuit that amplifies and outputs the autophase signal output from the autophase sensor. An inkjet recording device, The control device is After ink ejection has started and before the inkjet recording device enters a standby state, auto-phase gain adjustment is performed to adjust the auto-phase gain value of the amplification circuit in order to adjust the maximum voltage of the waveform of the auto-phase signal used to detect the timing of applying the charging voltage to the ink particles for abnormality detection. It is configured in such a way. Inkjet recording device.

2. In the inkjet recording apparatus according to claim 1, The control device is Based on the auto-phase gain value obtained by the auto-phase gain adjustment, the abnormality determination is performed. It is configured in such a way. Inkjet recording device.

3. In the inkjet recording apparatus according to claim 2, The control device is The abnormality determination is performed by determining whether or not the autophase gain value is within a predetermined range. If the autophase gain value is within the predetermined range, it is determined to be normal. If the autophase gain value is outside the predetermined range, it is determined to be abnormal. It is configured in such a way. Inkjet recording device.

4. In the inkjet recording apparatus according to claim 3, The control device is If the abnormality detection determines that the device is normal, the state of the inkjet recording device is controlled to be in the standby state. It is configured in such a way. Inkjet recording device.

5. In the inkjet recording apparatus according to claim 3, The control device is If the abnormality detection determines that an abnormality exists, the state of the inkjet recording device is controlled to enter a warm-up state. It is configured in such a way. Inkjet recording device.

6. In the inkjet recording apparatus according to claim 3, Equipped with a display device capable of displaying images, The control device is If the abnormality determination determines that an abnormality exists, a message indicating the abnormality will be displayed on the display device. It is configured in such a way. Inkjet recording device.

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