Ink jet 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 technology]

[0002] Inkjet recording devices may be used for long periods of time. In this case, in order to make the inkjet recording device in a state where it can print correctly, it is important to check normal values ​​by performing manual adjustments / operation checks on the operation screen and by performing excitation adjustments and auto phase gain adjustments before incorrect print results appear. If abnormal values ​​are recorded during excitation adjustments or auto phase gain adjustments, various factors may be considered, such as deterioration of the ink used, stains caused by ink or intensifying liquid around the gutter part in the print head, and defects in the board.

[0003] Patent Document 1 is a prior art related to the present invention. Patent Document 1 describes an inkjet recording device that can easily identify the cause of ink deterioration by displaying the result of the charging efficiency of ink particles in a waveform on an operation panel screen. The inkjet recording device of Patent Document 1 converts a phase detection signal in an analog signal form output from a sensor in which a voltage corresponding to the charge amount of ink particles charged with a phase search charging voltage is induced, into a digital signal form by an A / D converter, stores and saves the signal in a memory, and displays the result of the charging efficiency of ink particles in a waveform on a display device such as an operation panel. The inkjet recording device of Patent Document 1 can easily identify the cause of ink deterioration by displaying the result of the charging efficiency of ink particles in a waveform on an operation panel screen. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2013-10229 A Summary of the Invention [Problem to be solved by the invention]

[0005] The inkjet recording device is adjusted / operated by operating the screen when, for example, it is installed, shipped from the factory, when the board is replaced, or when the serviceman inspects it. The adjustment / operation check by operating the screen performed by the serviceman includes an excitation adjustment for adjusting the excitation voltage required to generate ink particles, an auto phase gain adjustment for adjusting the maximum voltage of the auto phase waveform for applying the charging voltage to the ink particles, a charging voltage check for checking that the voltage for charging the ink particles is output from the board, and a phase margin test for checking whether there is a phase margin by changing the phase for charging the ink particles and checking the printing. The auto phase gain adjustment adjusts the gain of the amplifier circuit in order to adjust the maximum voltage of the auto phase waveform for detecting the timing for applying the charging voltage to the ink particles.

[0006] When the condition of ink particles is poor due to ink deterioration or the like, or when droplets of print particles colliding with the print target are splashed onto the print head, if printing is continued for a long time without adjustments / operation checks such as excitation adjustment and auto phase gain adjustment before printing, ink and intensifying liquid gradually adhere to and accumulate on the orifice, charging electrode, positive deflection electrode, negative deflection electrode, gutter, or head tip surface in the print head, causing deterioration of print quality. Therefore, there is a demand for an inkjet recording device that can detect abnormal conditions (abnormalities) that cause deterioration of such print quality at an early stage.

[0007] The present invention has been made to solve the above problems, and it is an object of the present invention to provide an inkjet recording apparatus capable of detecting an abnormality at an early stage. [Means for solving the problem]

[0008] In order to solve the above problem, an inkjet recording device includes a print head that receives a supply of ink and prints, and a main body that includes a control device and 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 in which a voltage corresponding to the amount of charge of the ink particles is induced, and the main body has an amplifier circuit that amplifies and outputs an autophase signal output from the autophase sensor, and the control device is configured to perform autophase gain adjustment to adjust the autophase gain value of the amplifier circuit to adjust the maximum voltage of the waveform of the autophase signal to detect the timing of applying a charging voltage to the ink particles for abnormality judgment after ink ejection has started and before the inkjet recording device enters a standby state. Effect of the Invention

[0009] According to the present invention, it is possible to detect an abnormality at an early stage. Note that the effects described herein are not necessarily limited to those described herein, and may be any of the effects described in this disclosure. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a block diagram showing the configuration of an inkjet recording apparatus. [Diagram 2] FIG. 2 shows examples of ink droplet shapes formed by the voltage across the electrostrictive element in the print head. [Diagram 3] FIG. 3 is a diagram for explaining the phase search electrification signal. [Figure 4] FIG. 4 is a diagram showing an example of a waveform of the autophase signal. [Figure 5A] FIG. 5A is a diagram for explaining a case where the detection result of the autophase signal is abnormal. [Figure 5B] FIG. 5B is a diagram for explaining a case where the detection result of the autophase signal is abnormal. [Figure 6] FIG. 6 is a flow chart for explaining the operation of the inkjet recording apparatus. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In addition, in all the drawings of the embodiment, the same or corresponding parts may be denoted by the same reference numerals.

[0012] <<Embodiment>> DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a block diagram showing the configuration of an inkjet recording apparatus according to an embodiment of the present invention.

[0013] 1, the inkjet recording device includes an inkjet recording device main body 100 and a print head 200. The print head 200 is installed so as to face the transport path of a print target 400 transported by a conveyor 300 of a production line.

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

[0015] Furthermore, the inkjet recording device is equipped with an input panel 104 for inputting print contents, setting values, etc., and a display device 105 for displaying the input data and print contents, etc. The input panel 104 and 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. A bus line 106 (bus) transmits data signals, address signals, control signals, etc. of the MPU 101.

[0016] The print head 200 ejects ink 109, which is pressurized and supplied by an ink supply pump 108 from an ink container 107 in the inkjet recording apparatus main body 100, from a nozzle 201 in the form of an ink pillar 109a. An excitation signal is applied to an electrostrictive element 202 in the nozzle 201 by an excitation voltage generating circuit 112 in the inkjet recording apparatus main body 100, causing it to vibrate at a constant cycle. This causes the ink pillar 109a to become an ink droplet 109b. The electrostrictive element 202 is also called a "piezoelectric element."

[0017] The print head 200 is provided with a charging electrode 203 that surrounds the position where the ink pillar 109a becomes an ink drop 109b. When a regularly occurring ink drop (ink droplet) 109b separates from the ink pillar 109a, an electric charge is imparted to the ink drop 109b by the voltage of the charging electrode 203.

[0018] The print head 200 is equipped with a deflection electrode 204 that generates a deflection electric field that deflects the flying charged ink droplets 109b according to the amount of charge and directs them toward the print target 400 for printing. The print head 200 also has a gutter 205 that captures ink droplets 109b that were not used for printing, and an auto phase sensor 206 that is a phase detection sensor that generates a phase detection signal according to the amount of charge of the ink droplets 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 109 b captured by the gutter 205 into the ink container 107 .

[0020] The inkjet recording device main body 100 is equipped with an excitation voltage generating circuit 112 for generating an excitation signal for exciting an electrostrictive element 202 built into the print nozzle 201 in order to impart regularity to the timing at which the ink column 109a ejected from the print nozzle 201 separates into ink droplets 109b.

[0021] Furthermore, the inkjet recording apparatus main body 100 is equipped with a D / A converter 115 which converts the digital signal-type charging signals output from the printing charging signal generating circuit 113 and the phase search charging signal generating circuit 114 into analog voltage signals, and an amplifier circuit 116 which amplifies the analog voltage signal output from the D / A converter 115 to generate a charging voltage to be applied to the charging electrode 203.

[0022] Furthermore, the inkjet recording apparatus main body 100 includes a deflection voltage generating circuit 117 which generates a deflection voltage to be applied to the deflection electrode 204, an amplifier circuit 118 which amplifies a phase detection signal in the form of an analog signal output from the auto phase sensor 206, a phase determination circuit 119 which inputs the amplified phase detection signal and determines whether charging is good or bad, and an A / D converter 120 which inputs the amplified phase detection signal and performs A / D conversion.

[0023] The MPU 101 in the inkjet recording device configured as described above 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 and pressurizing the ink 109 in the ink container 107 and supplying it to the print nozzle 201, and ejecting an ink column 109a from the print nozzle 201 in a columnar shape, which is then separated into ink droplets 109b. In order to deflect the ink droplets 109b to a predetermined position, the print charging signal generating circuit 113 generates a charging signal and applies a charging voltage to the charging electrode 203 in accordance with the signal. The charged ink droplets 109b pass through the deflection electrode 204 and adhere to a predetermined position on the print target 400. The uncharged ink droplets 109b are collected in the gutter 205. The inkjet recording device sucks the ink droplets 109b captured by the gutter 205 and collects them in the ink container 107.

[0024] To operate an inkjet recording device, there are excitation signals, charging signals, automatic phase signals (also called "auto-phase signals" or "phase detection signals"), and deflection voltages. Among these, the auto-phase signal monitors the charging state in response to changes in ink particle timing caused by changes in ink viscosity due to changes in ambient temperature, changes in physical properties due to ink deterioration, and pressure changes due to vibrations from outside the inkjet recording device (print head or head cable), and controls the device to detect the optimal charging timing.

[0025] FIG. 2 shows examples of the shapes of ink droplets 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 mechanically vibrated in the direction in which the ink column 109a is ejected. The force of the vibration makes the ink belly 130 round and the constricted portion 131 narrow, eventually becoming an ink droplet 109b. A voltage is applied to the electrostrictive element 202 according to a signal from the excitation voltage generating circuit 112. The timing of the break point of the ink column 109a may change due to the influence of changes in pressure, temperature, ink substance, etc., and the ink droplet shape may change. In order to perform high-quality printing, it is necessary to apply a charging signal to the charging electrode 203 at the correct timing in addition to a normal ink droplet formation state. In order to reliably charge the ink droplets 109b, the inkjet recording device needs to accurately grasp the phase in which the ink droplets 109b are currently generated. Based on the result of detecting this phase, the timing of applying a charging signal to the charging electrode 203 is adjusted to charge the ink droplets 109b.

[0026] FIG. 3 is a diagram for explaining the phase search charging signal. According to the charging signal of the phase search charging signal generating circuit 114 in the inkjet recording apparatus main body 100, a phase search charging voltage is generated by dividing one period of the excitation signal into 16 equal parts (dividing equally is expressed as an electrical angle=phase, 0 to F phases). This is repeated 16 times up to the F phase. Note that it takes 10 [ms] per phase, and 16 phases take 160 [ms] to detect one auto phase, and the detection time is the auto phase detection period. A charging signal is applied 30 times continuously in the 0 phase to charge the ink particle 109b. This is performed for one period from the 0 phase to the F phase. The ink particle 109b charged by this phase search charging voltage is made large enough to deflect to such an extent that it does not jump over the gutter 205 (it can be captured by the gutter 205). An autophase signal output from the autophase sensor 206 in accordance with the charge amount of the ink droplet 109 b charged with this phase search charging voltage is amplified by an amplifier circuit 118 and input to a phase determination circuit 119 .

[0027] The waveform of the autophase signal output from the amplifier circuit 118 changes as shown in FIG. 4 with the change in the generation phase of the phase search charging voltage. The phase determination circuit 119 receives such an autophase signal, compares the input autophase signal of each phase with a threshold value, binarizes it, and inputs it 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 smaller than the threshold value, it is set to "0." The MPU 101 determines that the phase when the binarized autophase signal is further decreased by 2 from the phase where it changes from "1" to "0" is the optimal phase for generating the charging voltage for charging the ink particles 109b, and controls the printing charging signal so that the printing charging voltage is generated at that phase. This process is performed from the time ink is ejected until the standby state, and is performed continuously during ink ejection.

[0028] Cases where the detection result of the auto phase signal is abnormal are shown in Figures 5A and 5B. When the ink properties change due to deterioration of the ink, etc., and the ink droplet formation state becomes abnormal, the phase detection signal waveform changes as shown in Figure 5A. Figure 5B shows an example caused by 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 value. In such a state, the ink droplets 109b cannot be charged correctly, resulting in printing defects. In addition, the LED on the board blinks according to the binarized result, and if it is normal, it alternates between turning on and off, and if it is abnormal, it remains on or off and does not blink.

[0029] Therefore, before printing, the operator can observe the autophase signal waveform on the display device 105 while changing the excitation voltage applied to the nozzles, and if the waveform becomes abnormal and a message is displayed confirming ink deterioration, the operator can replace the ink and avoid printing defects before production.

[0030] The inkjet recording apparatus according to this embodiment is configured so that the autophase signal of each phase obtained in response to the phase search charging signal (charging voltage) of each phase in the phase search is converted into phase detection data in the form of a digital signal by the A / D converter 120, sampled (acquired) at appropriate intervals by the MPU 101, stored and saved in the RAM 103, and then read out from the RAM 103, processed into a waveform suitable for observation to identify the cause of a printing defect, and displayed on the display device 105. While changing the excitation voltage applied to the nozzle, if the waveform of the autophase signal becomes abnormal, a message to confirm ink deterioration is displayed.

[0031] Next, an outline of the operation of the inkjet recording apparatus according to the embodiment of the present invention will be described with reference to an example of a flowchart in Fig. 6. The inkjet recording apparatus starts its operation from step 600, and after executing an appropriate process among the processes of steps 601 to 609 described below, proceeds to step 610 and ends this operation flow.

[0032] Step 601: The inkjet recording apparatus main body 100 is powered 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 starting ink ejection, the MPU 101 automatically starts auto phase gain adjustment. The auto phase gain adjustment is an operation for adjusting the gain of the amplifier circuit 118 in order to adjust (to an appropriate voltage) the maximum voltage of the auto phase waveform (the waveform of the auto phase signal) for detecting the timing of applying the charging voltage to the ink droplets 109b.

[0035] For example, the auto phase gain adjustment adjusts the maximum voltage of the auto phase waveform for detecting the timing of applying the charging voltage to the ink particles 109b, and if there is a voltage of 7.5V or more in at least one phase of the voltage value detected by the APH sensor board (auto phase sensor 206) that actually charges the ink particles 109b, the auto phase gain value is lowered, and if there is no voltage, the auto phase gain value is raised. If there is a voltage of 2.5V or less in at least one phase of the last acquired APH voltages for 16 phases, the process ends normally, and if not, the process fails. The auto phase gain value is the gain value of the amplifier circuit 118.

[0036] Step 604: The MPU 101 acquires an auto phase gain value at a specific timing (eg, a time when the auto phase gain adjustment is normally completed).

[0037] Step 605: The MPU 101 judges whether the auto phase gain value is within a predetermined range (within a predetermined range). This performs an abnormality judgment to judge whether the inkjet recording device is abnormal. If the auto phase gain value is within the predetermined range, the inkjet recording device is highly likely to be normal. Therefore, in this case, the MPU 101 judges "YES" (determines that it is normal) and proceeds to step 606. If the auto phase gain value is outside the predetermined range, there is a possibility that an abnormality has occurred in the inkjet recording device. Therefore, in this case, the MPU 101 judges "NO" (determines that it is abnormal) and proceeds to step 608. The predetermined range is a range of auto phase gain values ​​suitable for abnormality judgment, and can be defined, for example, based on past knowledge (data) or by conducting experiments.

[0038] Step 606: The MPU 101 controls the inkjet recording device to enter a standby state. The "standby state" refers to a state in which no deflection voltage is applied for printing, ink is ejected, ink droplets 109b are generated, and the appropriate voltage application timing (optimum charging timing) has been detected.

[0039] Step 607: The MPU 101 controls the inkjet recording apparatus to be in a printable state, and printing is possible. The printable state is a state in which "ink is being ejected and a deflection voltage is being applied."

[0040] Step 608: The MPU 101 controls the inkjet recording apparatus to enter a warm-up state. The "warm-up state" is a state in which no deflection voltage is applied for printing, and ink is ejected and ink droplets 109b are generated, but the appropriate voltage application timing (optimum charging timing) has not 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 "The ink used may have deteriorated," "The inside of the print head may be dirty," "The board may be faulty," etc. As shown in block BR1, a user (or a serviceman) who has confirmed the message indicating an abnormality can eliminate the cause of the abnormality by replacing the ink, cleaning, or replacing the board.

[0042] <Effects> As described above, the inkjet recording device according to the embodiment of the present invention automatically performs auto phase gain adjustment for abnormality judgment when the inkjet recording device is turned on and starts ejecting ink. If the auto phase gain value of the auto phase gain adjustment is outside a predetermined range, the inkjet recording device performs an operation for notifying the user (or service person) of the abnormality (such as displaying an abnormality message screen) before printing, thereby notifying the user (or service person) in advance and preventing deterioration of print quality.

[0043] <<Modifications>> The present invention is not limited to the above embodiment, and various modified examples can be adopted within the scope of the present invention. For example, in the above embodiment, the abnormality determination is performed in two stages by determining either abnormality or normality based on the auto phase gain value, but the abnormality determination may be performed in three or more stages, such as normality, abnormality level 1, and abnormality level 2, based on the auto phase gain value. In the above embodiment, the inkjet recording apparatus may transmit a message indicating an abnormality to a terminal of a user (or a serviceman) via a network, and display the message indicating an abnormality on a display device of the terminal of the user (or the serviceman). [Explanation of symbols]

[0044] 100... inkjet recording device main body, 101... MPU, 102... ROM, 103... RAM, 104... input panel, 105... display device, 112... excitation voltage generating circuit, 113... print charge signal generating circuit, 114... phase search charge signal generating circuit, 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 a supply of ink and performs printing; a main body including a control device and configured to supply the ink to the print head; Equipped with The print head includes: a piezoelectric element for forming ink droplets from the ink; a charging electrode for charging the ink particles; a deflection electrode for deflecting the charged ink droplets; an autophase sensor in which a voltage is induced according to the amount of charge of the ink droplet; having The body includes: an amplifier circuit for amplifying and outputting the autophase signal output from the autophase sensor; An inkjet recording apparatus, The control device includes: performing an auto phase gain adjustment for adjusting an auto phase gain value of the amplifier circuit in order to adjust a maximum voltage of a waveform of the auto phase signal for detecting a timing for applying a charging voltage to the ink droplets in order to judge an abnormality after starting ink ejection and before the ink jet recording apparatus goes into a standby state; It was configured as follows: Inkjet recording device.

2. 2. The inkjet recording apparatus according to claim 1, The control device includes: performing the abnormality determination based on the auto phase gain value acquired by the auto phase gain adjustment; It was configured as follows: Inkjet recording device.

3. 3. The ink jet recording apparatus according to claim 2, The control device includes: performing the abnormality determination by determining whether the auto phase gain value is within a predetermined range; If the auto phase gain value is within the predetermined range, it is determined to be normal; If the auto phase gain value is outside the predetermined range, it is determined that the auto phase gain value is abnormal. It was configured as follows: Inkjet recording device.

4. 4. The ink jet recording apparatus according to claim 3, The control device includes: When it is determined that the inkjet recording apparatus is normal as a result of the abnormality determination, the inkjet recording apparatus is controlled so that the inkjet recording apparatus is in the standby state. It was configured as follows: Inkjet recording device.

5. 4. The ink jet recording apparatus according to claim 3, The control device includes: When it is determined that an abnormality has occurred as a result of the abnormality determination, the inkjet recording apparatus is controlled so that the state of the inkjet recording apparatus is in a warm-up state. It was configured as follows: Inkjet recording device.

6. 4. The ink jet recording apparatus according to claim 3, A display device capable of displaying an image is provided, The control device includes: When it is determined that an abnormality exists as a result of the abnormality determination, a message indicating the abnormality is displayed on the display device. It was configured as follows: Inkjet recording device.

Images