JP2010184355A - Method for manufacturing liquid delivering apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a liquid delivering apparatus capable of decreasing the fluctuation of delivering characteristics such as the flying speed and the weight of a liquid caused by a difference in an inherent vibration period Tc, and preventing a high electric voltage risk. <P>SOLUTION: A delivery driving pulse is constituted by including at least an expansion element p1 for expanding a pressure generating room, an expansion keeping element p2 for keeping an expanding state for a definite time, and a contracting element p3 for contracting the expanded pressure generating room to deliver liquid. A delivery driving pulse correcting process to be performed includes a Tc measuring step for measuring the inherent vibration period Tc of ink in the pressure generating room, a deviation calculating step for obtaining deviation between the measured Tc and the reference Tc, and an expansion keeping element correcting step for correcting a generating time of the expansion keeping element based on the deviation obtained. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a liquid discharge apparatus such as an ink jet printer, and in particular, a liquid discharge apparatus capable of controlling liquid discharge by applying a discharge drive pulse included in a drive signal to a pressure generating element. It relates to a manufacturing method.

  The liquid ejection apparatus is an apparatus that includes a liquid ejection head capable of ejecting liquid and ejects various liquids from the liquid ejection head. As a representative example of this liquid ejection apparatus, for example, an ink jet recording head (hereinafter simply referred to as a recording head) as a liquid ejection head is provided, and liquid ink is ejected from the nozzle of this recording head to a recording medium such as recording paper. An image recording apparatus such as an ink jet printer (hereinafter simply referred to as a printer) that records an image or the like by discharging and landing on a (landing target) can be given. In recent years, liquid ejecting apparatuses have been applied not only to the image recording apparatus but also to various manufacturing apparatuses such as a manufacturing apparatus for a color filter such as a liquid crystal display.

  The printer applies a discharge drive pulse to a pressure generating element (for example, a piezoelectric element or a heating element) and drives it to apply a pressure change to the liquid in the pressure generating chamber, and the pressure change is used to generate a pressure. Some are configured to discharge liquid from a nozzle communicating with the generation chamber. This discharge drive pulse is an expansion element that preliminarily expands the pressure generation chamber (pressure generation chamber expansion process), an expansion maintenance element that maintains this expansion state (expansion maintenance process), and the pressure generation chamber rapidly contracts from the expansion state. Thus, it is configured to include a contraction element (pressure generation chamber contraction step) for discharging ink by increasing the internal pressure of the pressure generation chamber.

  Depending on the parameters of the ejection drive pulse, the ejection characteristics such as the liquid amount (weight / volume) of ink ejected from the nozzles and the flight speed change. Specific examples include the drive voltage of the ejection drive pulse (potential difference between the lowest potential and the highest potential), the inclination of the expansion element (generation time), the inclination of the contraction element (generation time), and the like. That is, the discharge characteristics change depending on the time for maintaining the expanded state of the pressure generating chamber. That is, when the pressure generating chamber is expanded by the expansion element and the meniscus is drawn to the pressure generating chamber side, pressure vibration is generated in the ink in the pressure generating chamber. The ejection characteristics vary according to the phase of the pressure vibration when the pressure generating chamber is contracted by the pressure generating / shrinking element, that is, the position of the meniscus in the nozzle. For this reason, at the time of manufacturing the printer, the parameters of the ejection drive pulse are set so that desired ejection characteristics can be obtained. For example, in the configuration of Patent Document 1, an example in which the generation time of the expansion maintaining element (supply time to the pressure generation element) is set to the natural vibration period Tc of the ink in the pressure generation chamber is disclosed.

  FIG. 9 is a graph for explaining the relationship of the ink flying speed with respect to the time width of the expansion maintaining element (expansion hold element) (hereinafter, Pwh1-Vm characteristic). The horizontal axis represents the expansion maintaining element generation time Pwh1, and the vertical axis represents the ink flying speed Vm. Further, in this example, some of the nozzles belonging to the same nozzle row are picked up as sample nozzles to show the respective Pwh1-Vm characteristics. As shown in the figure, when the generation time Pwh1 of the expansion maintaining element is changed, the ink flying speed Vm increases or decreases accordingly. The fluctuation period of the flying speed Vm substantially coincides with the period of pressure vibration (natural vibration period Tc) generated in the ink in the pressure generation chamber. The ink vibration period Tc in the pressure generation chamber can be expressed by the following equation (1) as disclosed in, for example, Japanese Patent Application Laid-Open No. 2003-11352.

Tc = 2π√ [[(Mn × Ms) / (Mn + Ms)] × Cc] (1)
In Equation (1), Mn is an inertance at the nozzle, Ms is an inertance at the ink supply port leading from the reservoir to the pressure generation chamber, and Cc is a compliance of the pressure generation chamber (volume change per unit pressure, degree of softness) .) In the above equation (1), inertance M indicates the ease of ink movement in the ink flow path, and is the mass of ink per unit cross-sectional area. Then, assuming that the density of the ink is ρ, the cross-sectional area of the surface orthogonal to the ink flow direction of the flow path is S, and the length of the flow path is L, the inertance M can be expressed by the following equation (2). it can.
Inertance M = (density ρ × length L) / cross-sectional area S (2)
In addition, Tc is not limited to the above formula (1), and may be any vibration cycle that the pressure generation chamber has.

JP 2004-001562 A

  As described above, the natural vibration period Tc is determined individually depending on the size of the ink flow path in the head including the pressure generating chamber, the structure of the pressure generating element, and the like. For this reason, the natural vibration periods Tc may be different between the same type of recording heads or between the nozzle rows provided in the same recording head. In particular, in a printer in which a pressure generating element (piezoelectric element) is provided for each pressure generating chamber, Tc may be different between nozzles belonging to the same nozzle row as shown in FIG. For this reason, in the configuration in which the ejection drive pulse having the same waveform is used in common for each nozzle, there is a possibility that the ejection characteristics are different for each nozzle.

  In the conventional printer, for example, the occurrence time Pwh1 of the expansion maintaining element is set to a value near the peak indicated by A in FIG. In this case, even if Tc is slightly different between the nozzles, the variation in the flying speed Vm of the ink is small, so that it has not been regarded as a problem. However, in recent years, in order to shorten the waveform length of the ejection drive pulse itself and cope with the high frequency drive of the printer, the generation time Pwh1 of the expansion maintaining element is shorter than before, for example, from the peak as shown by B in FIG. There has been a need to set values outside the range. For this reason, when the Tc is different, the variation in the flying speed Vm of the ink tends to increase. When the flying speed Vm of the ink deviates from the design value, it can be adjusted by changing the drive voltage of the ejection drive pulse. Risk becomes a problem. This high voltage risk means that a limit value that can be used for the drive voltage of the ejection drive pulse is set in relation to the IC used in the printer, and this upper limit value is exceeded. If the drive voltage exceeds the upper limit value, the printer will be treated as a defective product, and the yield will decrease.

  The present invention has been made in view of such circumstances, and an object of the present invention is to reduce variations in ejection characteristics such as liquid flight speed and weight due to differences in the natural vibration period Tc, thereby preventing a high voltage risk. An object of the present invention is to provide a method for manufacturing a liquid ejection device that can be used.

The present invention has been proposed in order to achieve the above object. By applying a discharge driving pulse to a pressure generating element, a pressure fluctuation is generated in the pressure generating chamber, and the liquid is discharged from the nozzle by the pressure fluctuation. A method for manufacturing a liquid ejection device, comprising:
The ejection drive pulse includes at least an expansion element that expands the pressure generation chamber, an expansion maintenance element that maintains the expanded state for a certain period of time, and a contraction element that contracts the expanded pressure generation chamber to discharge liquid.
A Tc measurement step of measuring the natural vibration period Tc of the liquid in the pressure generating chamber;
A deviation calculating step for obtaining a deviation between the measured Tc and the reference Tc;
An ejection driving pulse correction process including an expansion maintaining element correction step of correcting the generation time of the expansion maintaining element based on the obtained deviation is performed.

In the above configuration, a configuration in which the reference Tc is Tc corresponding to any nozzle belonging to the same nozzle row can be adopted.
In addition, it is possible to adopt a configuration in which the reference Tc is an average value of Tc of each nozzle constituting a nozzle row of a plurality of nozzle rows belonging to the same liquid ejection head.

  According to the present invention, the natural vibration period Tc of the liquid in the pressure generation chamber is measured, the deviation between the measured Tc and the reference Tc is obtained, and the generation time of the expansion maintaining element of the ejection drive pulse is set based on the deviation. Therefore, it is possible to reduce variations in ejection characteristics such as the flying speed and weight of the liquid due to the difference in Tc. Thereby, the setting range of the appropriate value of the drive voltage of the ejection drive pulse can be reduced, and the risk of high voltage can be reduced.

FIG. 2 is a block diagram illustrating an electrical configuration of an ink jet printer. It is a perspective view of a recording head. FIG. 3 is a cross-sectional view of a main part of the recording head. It is a wave form diagram explaining the structure of a drive signal. It is a wave form diagram explaining the structure of an ejection drive pulse. It is a flowchart explaining the flow of an ejection drive pulse correction process. It is a graph which shows a Pwh1-Vm characteristic. It is the graph which expanded the area | region X in FIG. It is a graph which shows a Pwh1-Vm characteristic. It is a graph which shows the difference in Tc for every nozzle.

  The best mode for carrying out the present invention will be described below with reference to the accompanying drawings. In the embodiments described below, various limitations are made as preferred specific examples of the present invention. However, the scope of the present invention is not limited to the following description unless otherwise specified. However, the present invention is not limited to these embodiments. In the following, an ink jet recording apparatus (hereinafter referred to as a printer) will be described as an example of the liquid ejection apparatus of the present invention.

  FIG. 1 is a block diagram illustrating the electrical configuration of the printer. The illustrated printer includes a printer controller 1 and a print engine 2. The printer controller 1 includes an external interface (external I / F) 3 that transmits and receives data to and from an external device such as a host computer (not shown), a RAM 4 that stores various data, and controls for various data processing. ROM 5 storing a program and the like, a control unit 6 including a CPU, an oscillation circuit 7 that generates a clock signal, a drive signal generation circuit 9 that generates a drive signal COM to be supplied to the recording head 8, pixel data SI and An internal interface 10 (internal I / F 10) for transmitting drive signals and the like to the print engine 2 is provided.

  The external I / F 3 receives print data such as image data from a host computer or the like. Further, the external I / F 3 outputs a status signal such as a busy signal or an acknowledge signal to the external device. The RAM 4 is used as a reception buffer, an intermediate buffer, an output buffer, a work memory, and the like. The ROM 5 stores various control programs executed by the control unit 6, font data and graphic functions, various procedures, and the like. The print data includes various command data in addition to image data to be printed. The command data is data for instructing the printer to execute a specific operation. The command data includes, for example, command data for instructing paper feed, command data for indicating the carry amount, and command data for instructing paper discharge.

  The control unit 6 outputs a head control signal for controlling the operation of the recording head 8 to the recording head 8 and outputs a control signal for generating the driving signal COM to the driving signal generation circuit 9. The head control signal is, for example, a transfer clock CLK, pixel data SI, a latch signal LAT, and a change signal CH. These latch signals and change signals define the supply timing of each drive pulse constituting the drive signal COM. The control signal for generating the drive signal COM is, for example, a DAC (Digital to Analog Converter) value. This DAC value is information for instructing a voltage to be output from the drive signal generation unit 9, and is updated every extremely short update period.

  Further, the control unit 6 performs color conversion processing from the RGB color system to the CMY color system, halftone processing for reducing multi-gradation data to a predetermined gradation, and halftoned data based on the print data. Then, pixel data (dot pattern data) SI used for ejection control of the recording head 8 is generated through a dot pattern development process or the like arranged in a predetermined arrangement for each ink type (for each nozzle array) and developed into dot pattern data. This pixel data SI is data relating to pixels of an image to be printed, and is a kind of ejection control information. Here, the pixel indicates a dot formation region that is virtually determined on a recording medium such as a recording paper that is a landing target. The pixel data SI in the print data includes data (tone values) relating to the presence / absence of dots formed on the paper (or presence / absence of ink ejection) and the size of the dots (or the amount of ink ejected). . In the present embodiment, the pixel data SI is composed of 2-bit gradation values. That is, the pixel data SI includes data [00] corresponding to no dot (slight vibration), data [01] corresponding to small dots, data [10] corresponding to formation of medium dots, and large dots. There is data [11] corresponding to. Therefore, this printer in this embodiment can form dots with four gradations.

  FIG. 4 is a diagram for explaining an example of the configuration of the drive signal COM generated by the drive signal generation circuit 9. The drive signal COM in the present embodiment is a series of signals having one fine vibration pulse and four ejection drive pulses within a predetermined generation period (recording period) T, and is repeatedly generated at the recording period T. In the present embodiment, one recording cycle T of the drive signal COM is divided into five periods (pulse generation periods) t1 to t5. Then, the first ejection driving pulse P11 is generated in the period t1, the second ejection driving pulse P12 is generated in the period t2, the slight vibration pulse VP is generated in the period t3, and the third ejection driving pulse P13 is generated in the period t4. In the period t5, the fourth ejection driving pulse P14 is generated.

  Next, the print engine 2 will be described. As shown in FIG. 1, the print engine 2 includes a recording head 8, a carriage moving mechanism 44, a paper feeding mechanism 45, a linear encoder 46, and the like. The carriage moving mechanism 44 includes a carriage to which a recording head 8 that is a kind of liquid ejection head is attached, a drive motor (for example, a DC motor) that travels the carriage via a timing belt or the like (both shown in the figure). The recording head 8 mounted on the carriage is moved in the main scanning direction. The paper feed mechanism 45 includes a paper feed motor, a paper feed roller, and the like, and sequentially feeds recording paper (one type of recording medium and one type of landing target) onto the platen to perform sub-scanning. The linear encoder 46 outputs an encoder pulse corresponding to the scanning position of the recording head 8 mounted on the carriage to the control unit 6 through the internal I / F 10 as position information in the main scanning direction. The control unit 6 can grasp the scanning position (current position) of the recording head 8 based on the encoder pulse received from the linear encoder 46 side.

  As shown in FIGS. 2 and 3, the recording head 8 is composed of a pressure generating unit 15 and a flow path unit 16, which are integrated in a superposed state. The pressure generating unit 15 includes a pressure generating chamber plate 18 for partitioning the pressure generating chamber 17, a communication port plate 19 having a supply side communication port 22 and a first communication port 24a, and a diaphragm mounted with a piezoelectric element 20. 21 are laminated and integrated by firing or the like. The flow path unit 16 includes a supply port plate 25 in which a supply port 23 and a second communication port 24b are formed, a reservoir plate 27 in which a reservoir 26 and a third communication port 24c are formed, and a nozzle plate in which nozzles 28 are formed. It is comprised by adhere | attaching the plate member which consists of 29 in a laminated state. The nozzle plate 29 includes a plurality of (for example, 180) nozzles 28 arranged in a row to form a nozzle row. This nozzle row is provided for each color of ink, for example.

  A piezoelectric element 20 is disposed on the outer surface of the diaphragm 21 on the side opposite to the pressure generation chamber 17 in correspondence with each pressure generation chamber 17. The illustrated piezoelectric element 20 is a vibrator in a flexural vibration mode, and is configured with a piezoelectric body 20c sandwiched between a drive electrode 20a and a common electrode 20b. When a drive signal (ejection drive pulse) is applied to the drive electrode of the piezoelectric element 20, an electric field corresponding to the potential difference is generated between the drive electrode 20a and the common electrode 20b. This electric field is applied to the piezoelectric body 20c, and deforms according to the strength of the electric field applied with the piezoelectric body 20c. That is, as the potential of the drive electrode 20a is increased, the piezoelectric layer 20c contracts in a direction orthogonal to the electric field, and the diaphragm 21 is deformed so that the volume of the pressure generating chamber 17 is reduced.

  Next, the electrical configuration of the recording head 8 will be described. As shown in FIG. 1, the recording head 8 includes a shift register (SR) circuit including a first shift register 33 and a second shift register 34, and a latch circuit including a first latch circuit 35 and a second latch circuit 36. A decoder 37, a control logic 38, a level shifter 39, a switch 41, and the piezoelectric element 20. Each shift register 33, 34, each latch circuit 35, 36, level shifter 39, switch 41, and piezoelectric element 20 are provided in a number corresponding to each nozzle 28. In FIG. 2, only the configuration for one nozzle is shown, and the configuration for the other nozzles is omitted.

  The recording head 8 performs ink ejection control based on the pixel data SI sent from the printer controller 1. In this embodiment, since the upper bit group of the pixel data SI composed of 2 bits and the lower bit group of the pixel data SI are sent to the recording head 8 in synchronization with the clock signal CLK, first, the pixel data SI Are set in the second shift register 34. When the upper bit group of the pixel data SI is set in the second shift register 34 for all the nozzles 28, the upper bit group is then shifted to the first shift register 33. At the same time, the lower bit group of the pixel data SI is set in the second shift register 34.

  A first latch circuit 35 is connected to the subsequent stage of the first shift register 33, and a second latch circuit 36 is connected to the subsequent stage of the second shift register 34. When a latch pulse from the printer controller 1 side is input to the latch circuits 35 and 36, the first latch circuit 35 latches the upper bit group of the pixel data SI, and the second latch circuit 36 receives the pixel data SI. Latch the lower bit group. The pixel data SI (upper bit group, lower bit group) latched by the latch circuits 35 and 36 is output to the decoder 37, respectively. The decoder 37 generates pulse selection data for selecting each pulse constituting the drive signal COM based on the upper bit group and the lower bit group of the pixel data SI. For example, in the case of the drive signal COM in FIG. 2, the pulse selection data includes the first ejection drive pulse P11 (period t1), the second ejection drive pulse P12 (period t2), the minute vibration pulse VP (period t3), the third The data is composed of data of a total of 5 bits corresponding to the ejection drive pulse P13 (period t4) and the fourth ejection drive pulse P14 (period t5).

  A timing signal from the control logic 38 is also input to the decoder 37. The control logic 38 generates a timing signal in synchronization with the input of a latch signal or a channel signal. Each pulse selection data generated by the decoder 37 is sequentially input to the level shifter 39 from the upper bit side at the timing defined by the timing signal. The level shifter 39 functions as a voltage amplifier. When the pulse selection data is [1], the level shifter 39 outputs an electric signal boosted to a voltage capable of driving the switch 41, for example, a voltage of about several tens of volts.

  A drive signal COM from the drive signal generator 9 is supplied to the input side of the switch 41. The piezoelectric element 20 is connected to the output side of the switch 41. That is, the switch 41 is configured to switch between supply and non-supply of the drive signal COM to the piezoelectric element 20. The switch 41 that operates in this manner functions as a selection supply unit. The above pulse selection data controls the operation of the switch 41. That is, during the period when the pulse selection data input to the switch 41 is [1], the switch 41 is in a conductive state, and the drive signal COM1 is supplied to the piezoelectric element 20. On the other hand, while the pulse selection data input to the switch 41 is [0], the switch 41 is in a disconnected state, and no drive signal is supplied to the piezoelectric element 20. In short, a pulse in a period in which [1] is set as pulse selection data is selectively supplied to the piezoelectric element 20. By such switch control, the ejection drive pulse included in the drive signal COM can be applied to the piezoelectric element 20. That is, a part of the drive signal COM can be selectively applied to the piezoelectric element 20. In this example, the piezoelectric element 20 is at the boundary timing (change pulse timing of the change signal CH) between t1 and t5 after the start timing (latching pulse timing of the latch signal LAT) of the repetition cycle (recording cycle) T. The pulse applied to can be switched.

  As shown in FIG. 5, each of the ejection drive pulses P11 to P14 included in the drive signal COM includes an expansion element p1, an expansion hold element p2 (expansion maintaining element), a contraction element p3, a vibration suppression hold element p4, It consists of damping element p5. The expansion element p1 is a waveform element that lowers the potential from the intermediate potential VB (reference potential) corresponding to the steady volume (volume serving as a reference for expansion or contraction) of the pressure generating chamber 17 to the expansion potential VL. The expansion hold element p2 Is a waveform element constant at the expansion potential VL. The contraction element p3 is a waveform element that increases the potential with a steep slope from the expansion potential VL to the contraction potential VH, and the vibration suppression hold element p4 is a waveform element that maintains the contraction potential VH for a predetermined period. The damping element p5 is a waveform element that lowers the potential from the contraction potential VH to the intermediate potential VB.

  When the ejection drive pulse configured as described above is supplied to the piezoelectric element 20, first, the piezoelectric element 20 is bent in a direction away from the pressure generating chamber 17 by the expansion element p1, and thereby the pressure generating chamber 17 is set to the intermediate potential VB. It expands from the steady volume corresponding to the expansion volume corresponding to the expansion potential VL. Due to this expansion, the meniscus is largely drawn to the pressure generating chamber 17 side, and ink is supplied into the pressure generating chamber 17 from the reservoir 26 side through the supply port. The expansion state of the pressure generation chamber 17 is maintained over the generation period (Pwh1) of the expansion hold element p2. Thereafter, the piezoelectric element 20 is bent toward the pressure generation chamber 17 by applying the contraction element p3. Due to the displacement of the piezoelectric element 20, the pressure generating chamber 17 is rapidly contracted from the expansion volume to the contraction volume corresponding to the contraction potential VH. The ink in the pressure generating chamber 17 is pressurized by the rapid contraction of the pressure generating chamber 17, and a predetermined amount (for example, several ng to several tens of ng) of ink is ejected from the nozzle 28. The contraction state of the pressure generation chamber 17 is maintained over the supply period of the vibration suppression hold element p4. During this period, the ink pressure in the pressure generation chamber 17 that has decreased due to ink ejection rises again due to its natural vibration. The damping element p5 is adjusted so as to be supplied in accordance with the rising timing. By supplying the damping element p5, the pressure generation chamber 17 expands and returns to the steady volume, and ink pressure fluctuation (residual vibration) in the pressure generation chamber 17 is absorbed.

  Here, when the printer is manufactured, the parameters of the ejection driving pulse are set so that desired ejection characteristics can be obtained. In general, the ejection driving pulse is commonly used for all the nozzles 28 of the recording head 8. However, the natural vibration period Tc generated in the ink in the pressure generation chamber may be different between the same type of print heads or between the nozzle rows provided in the same print head. In particular, like the printer in this embodiment. In the configuration in which the piezoelectric element 20 is provided for each pressure generation chamber 17, the Tc may be different between the nozzles 28 belonging to the same nozzle row. When Tc is different for each nozzle, there is a possibility that the ejection characteristics may be different for each nozzle in a configuration in which ejection drive pulses having the same waveform are commonly used for each nozzle 28. In a general printer, the drive voltage Vd of the ejection drive pulse (potential difference between the expansion potential VL which is the lowest potential and the contraction potential VH which is the highest potential) is also adjusted in order to align the ejection characteristics between the nozzles. If the difference in ejection characteristics is large, there is a concern that the high voltage risk that the drive voltage Vd exceeds the settable upper limit value.

  Therefore, in the printer according to the present invention, the above-described problem is solved by correcting the generation time Pwh1 of the expansion hold element p2 of the ejection drive pulse, in which the parameters are determined in advance, based on the natural vibration period Tc. That is, the natural vibration period Tc generated in the ink in the pressure generation chamber 17 in the manufacturing stage is measured, and the ejection drive pulse correction process for correcting the generation period Pwh1 of the expansion hold element p2 of the ejection drive pulse based on the measured Tc is performed. . Hereinafter, this point will be described.

  FIG. 6 is a flowchart for explaining the flow of the ejection drive pulse correction process. In the present embodiment, the ejection drive pulse correction process includes three steps: a Tc measurement step S1, a deviation calculation step S2, and a Pwh1 correction step S3 (expansion maintaining element correction step). In the Tc measurement step S1, for example, the nozzle row is divided into several blocks, a representative nozzle 28 is picked up as a sample nozzle for each block, and Tc for the picked up sample nozzle is measured (taken up as a sample nozzle). (The number can be set arbitrarily. Of course, 100% measurement may be adopted.) As a measuring method of Tc, while changing the generation time Pwh1 of the expansion hold element p2 within a predetermined range, the ink flying speed Vm and the ink weight when ink is ejected by the ejection driving pulse are measured, and the change is measured. It is possible to use existing techniques such as a method of observing and obtaining the interval between adjacent maximum values or minimum values of the change curve as Tc.

  FIG. 7 shows a case where Pwh1 is measured when Tc corresponding to the 30th and 90th nozzles 28 is measured when one nozzle row is composed of 100 nozzles 28 from 1st to 100th, for example. It is a graph which shows a Vm characteristic. FIG. 8 is a graph in which the region X in FIG. 7 is enlarged. As shown in these drawings, it can be seen that Tc is different between No. 30 and No. 90 nozzles 28 belonging to the same nozzle row. Specifically, Tc2 of the 30th nozzle 28 is shorter than Tc1 of the 90th nozzle 28. For this reason, these Pwh1-Vm appear to be out of phase.

  In the conventional printer, for example, the occurrence time Pwh1 of the expansion maintaining element is set to a value near the peak indicated by A in FIG. In this case, even if Tc is slightly different between the nozzles, the variation in the flying speed Vm of the ink is small, so that it has not been regarded as a problem. However, in recent years, in order to shorten the waveform length of the ejection drive pulse itself and cope with the high-frequency drive of the printer, the generation time Pwh1 of the expansion maintaining element is shorter than before, for example, as shown by B in FIG. There has been a need to set a value outside the range. In the present embodiment, Pwh1 of the expansion hold element p2 of the ejection drive pulse is preset to a value indicated by Pwx in FIG. For this reason, even if the difference in Tc is small, the variation in the flying speed Vm of the ink tends to increase. For example, the flying speed Vm2 when ink is ejected by the 30th nozzle 28 is greatly reduced compared to the flying speed Vm1 when ink is ejected by the 90th nozzle 28.

  In the deviation calculating step S2, a deviation from the reference Tc is obtained for Tc measured in the Tc measuring step. The reference Tc can be arbitrarily determined. For example, among the nozzles 28 belonging to the same nozzle row, a target special characteristic can be obtained when ink is ejected by an ejection driving pulse having a predetermined parameter. Tc corresponding to the nozzle 28 is used as a reference. In the present embodiment, Tc corresponding to the 90th nozzle 28 is set as the reference Tc. Therefore, in the deviation calculation step S2, the deviation α between Tc measured for the sample nozzles 28 other than the 90th nozzle 28 and the reference Tc is calculated. 7 and 8, the deviation between Tc1 of the 90th nozzle 28 and Tc2 of the 30th nozzle 28 is obtained (α = Tc1−Tc2). In the Pwh1 correction step S3, the generation time Pwh1 of the expansion hold element p2 of the ejection drive pulse used for the target nozzle 28 is corrected based on the deviation α obtained in the deviation calculation step S2. Specifically, the deviation α is subtracted from a preset value of Pwh1 (Pwh1-α). 7 and 8, Pwx is reduced by α (Pwx ′ = Pwx− (Tc1−Tc2)), and the calculated value Pwx ′ is set as the generation time Pwh1 of the expansion hold element p2 of the ejection drive pulse.

  Regarding the correction method of Pwh1, the absolute value of the deviation is taken (| α |), and when Tc of the target nozzle 28 is longer than the reference Tc, | α | is added to Pwh1, and If Tc is shorter than the reference Tc, | α | may be subtracted from Pwh1. The exemplified correction is for the case where Pwh1 is set in a range where the Pwh1-Vm characteristic is displaced from the maximum value to the minimum value, and Pwh1 is set in the range where the Pwh1-Vm characteristic is displaced from the minimum value to the maximum value. In this case, the addition / subtraction is reversed from the case of the present embodiment.

In this way, by correcting Pwh1 based on the measured Tc and using the corrected ejection drive pulse for the nozzle 28 corresponding to the Tc, the ejection characteristics of each nozzle 28 can be brought close to the target value. it can. That is, in the example of FIG. 8, the value of Pwh1 is corrected from Pwx to Pwx ′, and the corrected ejection drive pulse is used for each nozzle 28 of the block to which the 30th nozzle 28 belongs. The flying speed of the ink ejected from the nozzle 28 can be made equal to the flying speed Vm1 of the ink ejected from the 90th nozzle 28. Therefore, it is not necessary to adjust the drive voltage Vd of the ejection drive pulse, or even when the drive voltage Vd is adjusted, the adjustment range is narrower than before correction, so that a high voltage risk can be prevented.
The process of correcting Pwh1 according to the natural vibration period Tc described in the above embodiment may be performed at the time of manufacturing the printer, may be performed at the time of using the printer after manufacturing, or may be performed again at the time of maintenance of the printer. It may be performed as a setting.

  By the way, the present invention is not limited to the above-described embodiment, and various modifications can be made based on the description of the scope of claims.

  For example, the waveform configuration of the ejection drive pulse is not limited to that exemplified in the above embodiment, and the present invention can be applied to ejection drive pulses having various configurations. The point is an ejection driving pulse having at least an expansion element that expands the pressure generation chamber, an expansion maintenance element that maintains the expanded state for a certain period of time, and a contraction element that contracts the expanded pressure generation chamber to discharge liquid. I just need it.

  Moreover, in the said embodiment, although the structure which arranges the discharge characteristic between the nozzles which belong to the same nozzle row was illustrated, it is not restricted to this. For example, in a recording head having a plurality of nozzle rows, it is possible to make the ejection characteristics between the nozzle rows uniform. In this case, Tc is obtained for each nozzle row by calculating the average value of Tc of each nozzle constituting the nozzle row, and Pwh1 of the ejection drive pulse corresponding to each nozzle row is obtained based on Tc of any nozzle row. Can be corrected. Of course, as the reference Tc, it is not always necessary to adopt Tc of any nozzle row, and an ideal value in design can be adopted.

  Note that the present invention is not limited to a printer as long as it is a liquid ejection apparatus capable of controlling liquid ejection using a drive signal (ejection drive pulse), and various ink jet recording apparatuses such as a plotter, a facsimile machine, and a copier. It can also be applied to liquid ejection devices other than recording devices, such as display manufacturing devices, electrode manufacturing devices, chip manufacturing devices, and the like.

  DESCRIPTION OF SYMBOLS 1 ... Printer controller, 2 ... Print engine, 6 ... Control part, 8 ... Recording head, 9 ... Drive signal generation circuit, 20 ... Piezoelectric element

Claims (3)

A method of manufacturing a liquid ejection apparatus, in which a pressure fluctuation is generated in a pressure generation chamber by applying a ejection driving pulse to a pressure generating element, and a liquid is ejected from a nozzle by the pressure fluctuation,
The ejection drive pulse includes at least an expansion element that expands the pressure generation chamber, an expansion maintenance element that maintains the expanded state for a certain period of time, and a contraction element that contracts the expanded pressure generation chamber to discharge liquid. And
A Tc measurement step of measuring the natural vibration period Tc of the liquid in the pressure generating chamber;
A deviation calculating step for obtaining a deviation between the measured Tc and the reference Tc;
A method of manufacturing a liquid ejection device, comprising: performing an ejection drive pulse correction process including an expansion maintenance element correction step of correcting an occurrence time of the expansion maintenance element based on the obtained deviation.   The method of manufacturing a liquid ejection apparatus according to claim 1, wherein the reference Tc is Tc corresponding to any nozzle belonging to the same nozzle row.   2. The liquid ejection apparatus according to claim 1, wherein the reference Tc is an average value of Tc of each nozzle constituting one of the plurality of nozzle arrays belonging to the same liquid ejection head. Production method.

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