JP4141992B2 - Inkjet recording apparatus and recording method - Google Patents

Description

  The present invention relates to an ink jet recording apparatus and a recording method, and more particularly, to an ink jet recording apparatus and a recording method for preventing an increase in ink viscosity by imparting vibration to the ink to such an extent that ink droplets are not ejected.

  The ink jet printer has a print head having a large number of nozzles in the sub-scanning direction (vertical direction), and the print head is moved in the main scanning direction (horizontal direction) by a carriage mechanism to feed a predetermined paper. To obtain a desired print result. Based on dot pattern data obtained by developing print data input from the host computer, ink droplets are ejected from each nozzle of the print head at a predetermined timing, and these ink droplets are printed on paper, OHP sheets, etc. Printing is performed by landing and adhering to the recording medium.

  Here, in order to prevent printing blur or the like, it is preferable that the ink droplets adhering to the paper are quickly dried and solidified. Therefore, in general, the ink components are prepared so that the ink solvent volatilizes quickly. However, ink droplets are rarely ejected from all nozzles at all times, and each nozzle ejects ink droplets at a predetermined position during main scanning. That is, during the entire period in which one main scan is performed, each nozzle has an ejection period in which ink droplets are ejected and a non-ejection period in which ink droplets are not ejected. Therefore, during a period when ink droplets are not ejected, water and the like evaporate from the nozzle openings, and the ink viscosity increases (hereinafter also referred to as “thickening”). In particular, since the nozzles positioned at the upper and lower ends of the print head have fewer opportunities to use than the nozzles near the center, the non-ejection period is lengthened and the ink viscosity is likely to increase. When the ink viscosity increases, not only the flying stability of the ink droplets is impaired, but the nozzles are eventually clogged and the print quality is deteriorated.

  Therefore, in order to prevent clogging of the nozzle, the flushing operation is performed under a predetermined condition. That is, periodically, the print head is retreated to the cleaning area to forcibly eject a small amount of ink droplets from all the nozzles, and the ink in the vicinity of the nozzle opening is replaced.

  If the flushing operation is performed, the ink in the vicinity of the nozzle opening can be forcibly replaced with a new one, but the ink that is forcibly discarded is wasted, resulting in an increase in printing cost. Further, since printing must be interrupted during the flushing operation, the printing speed per page decreases and the printing time increases. In particular, since color printing has become widespread in recent years, the above-described problem related to increase in ink viscosity occurs for each color nozzle.

For this reason, for example, Japanese Patent Application Laid-Open No. H10-228707 proposes a technique for exchanging ink by slightly vibrating a meniscus during main scanning, instead of interrupting printing and forcibly ejecting ink. In other words, in this type of technology, a minute pulse signal is applied to the piezoelectric vibrator during main scanning, so that the meniscus is vibrated to the extent that ink droplets are not ejected, and new ink in the vicinity of the nozzle opening is renewed. It is designed to be replaced with a new ink.
JP-A-57-61576

  In the prior art described in the above publication, the meniscus is vibrated slightly to prevent the ink viscosity from increasing. However, if the meniscus is vibrated frequently, the evaporation of the solvent or the like is caused, and the ink viscosity increases. May end up. Further, since it takes some time until the vibration of the meniscus is sufficiently attenuated, for example, when the meniscus is slightly vibrated immediately before ejecting the ink droplet, the amount, shape, flight path, etc. of the ejected ink droplet are It may fluctuate, resulting in a decrease in print quality. In addition, the influence of the slight vibration of the meniscus on the ink viscosity in the vicinity of the nozzle opening varies depending on the ambient temperature and changes with time of the ink. Therefore, the meniscus is uniform as various parameters change every moment. If the ink is slightly vibrated, excessive fine vibration is applied, and the ink viscosity may increase. In other words, in the prior art, the relationship between the operating state of each nozzle (when and where ink droplets are ejected), the surrounding environment, and the fine vibration applied to the meniscus is insufficient, and the increase in ink is not always sufficient. Cannot prevent stickiness.

  The present invention has been made in view of the above problems, and its purpose is to slightly increase the meniscus according to the operating state of each nozzle, thereby preventing an increase in ink viscosity and preventing ink droplets from flying. The present invention relates to an ink jet recording apparatus and a recording method that can be stabilized.

In the invention which concerns on Claim 1, it has a print head provided with a pressure generating element corresponding to each of a plurality of nozzles, and by operating each of the pressure generating elements based on input data, In the ink jet recording apparatus for ejecting ink droplets, drive signal generating means for generating a printing drive signal for ejecting ink droplets and a micro-vibration drive signal for operating the pressure generating element to such an extent that ink droplets are not ejected Pattern data comprising: print bit data for selecting the print drive signal and fine vibration bit data for selecting the fine vibration drive signal based on the input print data Data generating means for generating the print drive based on the dot pattern data input from the data generating means Respect No. and the micro-vibration drive signal and the pressure generating element, and an input can switch means in one printing period is one period which can form a printed dot of said data generating means, said selects a predetermined pattern of the corresponding to the discharge state of each nozzle to be analyzed on the basis of the print data, in accordance with the predetermined pattern, the micro-vibration for micro-vibration performed before each ejection data for ejecting ink The dot pattern data is generated by setting the working bit data at a predetermined position.

  Here, the “pressure generating element” means an element that causes a pressure change in ink according to an input signal, and preferably employs a piezoelectric vibrator that expands and contracts according to the input signal as shown in claim 12. can do. However, the present invention is not limited to this, and for example, a heat generating element that generates a bubble by heat generation and causes a pressure change of the ink by the bubble can be included in the pressure generating element. Further, the “fine vibration drive signal” means a signal for causing the meniscus to vibrate to such an extent that no ink droplet is ejected from the nozzle, and does not indicate the shape or voltage level of the signal itself. The bit data for printing and the bit data for micro vibration are typically expressed by binary values of “1” or “0”. When “1” is set in the print bit data, an ink droplet is ejected, and when “0” is set, no ink droplet is ejected. When “1” is set in the bit data for fine vibration, fine vibration is given to the meniscus, and when “0” is set, fine vibration is not given to the meniscus. The “operating state of each nozzle” indicates a forming state of printing dots by each nozzle, that is, in which printing cycle ink droplets are ejected.

  For example, when print data is input from a device that generates print data, such as a word processor, personal computer, workstation, or digital still camera, the data generation unit analyzes the operating state of each nozzle based on the print data, A predetermined pattern is selected according to the operating state of each nozzle. One or a plurality of predetermined patterns can be registered in advance. The data generating means sets the minute vibration bit data at a predetermined position according to a predetermined pattern, and generates dot pattern data. That is, in a large number of printing cycles constituting one main scan, the bit data for fine vibration is set to “1” in a printing cycle where fine vibration should be given, and “0” is set in a printing cycle where fine vibration should not be given. "Is set.

  The dot pattern data generated in this way is input to the switch means. When the bit data for fine vibration is set to “1”, the switch means inputs the drive signal for fine vibration generated by the drive signal generating means to the pressure generating element. As a result, the pressure generating element vibrates to the extent that ink droplets are not ejected, the meniscus slightly vibrates, and the ink is replaced. On the other hand, when the fine vibration data is set to “0”, the switch means does not input the fine vibration drive signal to the pressure generating element. In addition, when the printing bit data is set to “1”, the switch means inputs a printing driving signal to the pressure generating element to eject ink droplets, and the printing bit data is set to “0”. If it is set, the printing drive signal is not input to the pressure generating element.

  In this way, the meniscus can be given as much fine vibration as necessary according to the operating state of each nozzle, so that the increase in ink viscosity can be prevented and the flight of ink droplets can be stabilized. .

  According to a second aspect of the present invention, a first pattern is set as the predetermined pattern in the data generating means, and the first pattern is in a predetermined period immediately before ejecting ink droplets. The fine vibration bit data can be set so that the fine vibration drive signal is not selected in the print cycle, and the fine vibration drive signal is selected at a predetermined ratio in the other print cycles.

  That is, in the first pattern, when a certain nozzle discharges ink droplets at a predetermined location, the meniscus is not slightly oscillated for a predetermined period immediately before the printing cycle for discharging ink droplets, and is predetermined at other printing cycles. This gives a slight vibration to the meniscus. Specifically, for example, if the total number of printing cycles constituting a single main scan is N and the predetermined period is a time corresponding to three printing cycles, ink droplets are ejected in the nth printing cycle. In the case of (n-1) th, (n-2) th, and (n-3) th consecutive printing cycles, the meniscus is not vibrated and the other printing cycles, that is, In each of the first to (n-4) th printing cycles and the nth to Nth printing cycles, a slight vibration is applied to the meniscus at a predetermined ratio. However, this example is a case where a printing drive signal appears first and then a fine vibration drive signal appears in one printing cycle. On the other hand, if a drive signal for micro-vibration appears first and then a drive signal for printing appears in one printing cycle, the same printing cycle as the printing drive signal selected to eject ink droplets The minute vibration is not started from the middle vibration driving signal, that is, the (n) th printing cycle. Thereby, the fine vibration of the meniscus can be attenuated before ejecting the ink droplet, and the flight of the ink droplet can be stabilized. Note that “select at a predetermined ratio” means that the meniscus is finely vibrated at all printing cycles in which selection of the fine vibration drive signal is permitted (when the ratio is 100%), for example, 1 This means that it is possible to give a slight vibration to the meniscus at every other printing cycle (when the ratio is 50%).

  According to a third aspect of the present invention, a second pattern is set as the predetermined pattern in the data generation means, and the second pattern is in a first period immediately before ejecting ink droplets. The fine vibration bit data is selected so that the fine vibration drive signal is not selected in the print cycle, and the fine vibration drive signal is selected at a predetermined ratio in the print cycle in the second period immediately before the first period. Can also be set.

  In the second pattern, when a certain nozzle ejects an ink droplet at a predetermined location, the meniscus is not slightly vibrated in the printing cycle during the first period immediately before ejecting the ink droplet, and the second pattern continues immediately before the first period. In the printing cycle during the two periods, the meniscus is slightly vibrated. For example, the case where the first period is a time corresponding to three printing cycles, the second period is a time corresponding to five printing cycles, and ink droplets are ejected in the nth printing cycle will be described as an example. In this case, in the (n-1) th to (n-3) th consecutive printing cycles included in the first period, the meniscus is not subjected to slight vibration and is included in the second period (n- In the 4th to (n-8) th continuous printing cycles, the meniscus is slightly vibrated at a predetermined ratio. In each of the first to (n-9) th printing cycles and the nth to Nth printing cycles, no fine vibration is applied to the meniscus. As a result, it is possible to prevent the flying of the ink droplets from becoming unstable and to impart unnecessary fine vibrations to the meniscus.

  As in the invention according to claim 4, the first period and the second period can be set even in an acceleration region where the print head accelerates.

  The print head starts accelerating travel from a standby position outside the print area by the carriage mechanism, and moves to constant speed travel when the print reference position is reached. By applying the invention according to claim 2 to the acceleration region located outside the printing region, it is possible to prevent an increase in ink viscosity and the like even when ink droplets are ejected in the first printing cycle.

  According to a fifth aspect of the present invention, a third pattern is set as the predetermined pattern in the data generation unit, and the third pattern is in a first period immediately after ink droplets are ejected. The fine vibration bit is selected so that the fine vibration drive signal is not selected in the print cycle, and the fine vibration drive signal is selected at a predetermined ratio in the print period in the second period immediately after the first period. Data can also be set.

  The third pattern gives a slight vibration to the meniscus only in the second period after the ink droplet is ejected and after a first period. Specifically, assuming that the first period is a time corresponding to three printing cycles and the second period is a time corresponding to five printing cycles, when ink droplets are ejected in the nth printing cycle, the nth to (n + 2) The meniscus is not slightly oscillated in the three consecutive printing cycles up to the nth, and the meniscus is applied at a predetermined ratio in the five consecutive printing cycles from the (n + 3) th to the (n + 7) th. Gives slight vibration. As a result, it is possible to prevent unnecessary fine vibrations immediately after the ink droplets are discharged and the inks are replaced, and the meniscus is slightly vibrated when the solvent of the replaced inks evaporates. It can be replaced with new ink again.

  According to a sixth aspect of the present invention, a fourth pattern is set as the predetermined pattern in the data generation means, and the fourth pattern relates to a nozzle that does not eject ink droplets during main scanning. The fine vibration bit data may be set so that the fine vibration drive signal is selected at a predetermined ratio every predetermined period.

  The fourth pattern gives a fine vibration to the meniscus at a predetermined ratio for each predetermined period with respect to a nozzle that does not eject ink droplets even once during main scanning. Such idle nozzles are likely to occur in the nozzles located at the upper and lower ends of the print head. Typically, in so-called interlaced driving, idle nozzles are generated in the upper nozzle in the upper end process and the lower nozzle in the lower end process. Easy to do. Since the upper nozzle in the upper end process and the lower nozzle in the lower end process are often located outside the print area, ink droplets are often not ejected once during the main scan. Ink viscosity tends to increase. Therefore, the meniscus is periodically vibrated in the idle nozzle to prevent an increase in ink viscosity.

  As in the invention according to claim 7, at least one of a length of a period for setting the bit data for fine vibration so as to select the drive signal for fine vibration and the predetermined ratio depends on an environmental temperature. May be set variable.

  For example, parameters such as ink viscosity vary depending on the environmental temperature, so the period and ratio of fine vibration required by each nozzle differ depending on the environmental temperature. Therefore, for example, the adjustment is made according to the environmental temperature, such as reducing the ratio of giving micro-vibration in a high-temperature environment. The environmental temperature can be directly detected by a temperature detection element such as a thermistor provided on the main control board or the print head, for example, and can also be obtained indirectly from the accumulated operation time or the like.

  As in the invention according to claim 8, at least one of the length of the period for setting the bit data for fine vibration so as to select the drive signal for fine vibration and the predetermined ratio depends on the ink viscosity. Can be set to be variable.

  The ink viscosity increases as a solvent or the like evaporates from ink in the ink cartridge (or ink tank). A normal ink cartridge is formed from a material having water vapor permeability such as polyethylene resin, polyacetal resin, ABS resin and the like. Accordingly, as time passes after a new ink cartridge is mounted, the solvent inside the cartridge gradually evaporates to the outside, and the ink viscosity increases. Therefore, if the relationship between the elapsed time and the ink viscosity is obtained in advance by experiments or the like, the ink viscosity can be indirectly detected. The period and ratio of the fine vibration given to each nozzle are adjusted by the estimated ink viscosity. For example, as the ink viscosity in the cartridge rises, the period during which the minute vibration is applied can be lengthened, or the ratio at which the minute vibration is applied can be increased.

  That is, as in the invention according to claim 9, it is possible to set so that the period for setting the bit data for fine vibration becomes longer as the elapsed time after mounting the ink cartridge becomes longer. Further, as in the invention according to claim 10, the predetermined ratio can be set to be higher as the elapsed time after the ink cartridge is mounted becomes longer.

  According to the eleventh aspect of the present invention, at least one of the length of the period for setting the bit data for fine vibration so as to select the drive signal for fine vibration and the predetermined ratio is the solid content of the ink. It can also be set variably according to the concentration.

  The “solid content concentration” indicates the concentration of the color material component constituting the ink. Although it depends on the components of the color material, in general, an ink of a color that requires dark printing, typically a black ink, has a higher solid content concentration than other color inks, and yellow, light cyan, A light or light color such as light magenta has a low solid content concentration. Ink with a relatively high solid content concentration is considered to have a higher degree of thickening than an ink with a relatively low solid content concentration, and the required period and ratio of microvibration differ depending on the solid content concentration. To do. Therefore, if the solid content concentration for each color is obtained in advance, the period / ratio of fine vibration applied to each nozzle can be adjusted for each color.

  In the invention according to claim 13, in the ink jet recording method in which ink droplets are ejected from each nozzle by operating pressure generating elements provided corresponding to the plurality of nozzles, respectively, based on input print data Analyzing the operating state of each nozzle, selecting a predetermined pattern based on the analyzed operating state, and setting bit data for fine vibration at a predetermined position according to the selected predetermined pattern, When dot pattern data for print output is generated and the fine vibration bit data is set, a fine vibration drive signal that does not eject ink droplets is input to the pressure generating element. Yes.

  Thereby, the same effect as that of the invention according to claim 1 can be obtained.

  As described above, according to the ink jet recording apparatus and the recording method according to the present invention, by analyzing the print data, the print cycle to be given the minute vibration is determined and the dot pattern data is generated. Appropriate fine vibration can be given according to the operating state. Therefore, it is possible to prevent the ink viscosity from increasing and keep the ink droplets flying well, to improve the flushing efficiency and to consume ink without waste.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a functional block diagram of an ink jet printer as an ink jet recording apparatus to which the first embodiment of the present invention is applied.

1-1 Overall Configuration An ink jet printer includes a printer controller 1 and a print engine 2. The printer controller 1 includes an interface (hereinafter referred to as “I / F”) 3 that receives print data from a host computer (not shown), a RAM 4 that stores various data, a program for various data processing, and the like. ROM 5, a control unit 6 including a CPU, an oscillation circuit 7, a drive signal generation circuit 8 as “drive signal generation means” for generating a drive signal to the print head 20 described later, and dot pattern data And an I / F 9 for transmitting print data expanded in (bit map data), a drive signal, and the like to the print engine 2.

  The I / F 3 receives print data including, for example, any one or more of character code, graphic function, and image data from a host computer or the like. The I / F 3 can output a busy signal (BUSY), an acknowledge signal (ACK), and the like to the host computer.

  The RAM 4 is used as a reception buffer 4A, an intermediate buffer 4B, an output buffer 4C, a work memory (not shown), and the like. Print data from the host computer received by the I / F 3 is temporarily stored in the reception buffer 4A. In the intermediate buffer 4B, intermediate code data converted into an intermediate code by the control unit 6 is stored. In the output buffer 4C, as will be described later, ejection data as “print bit data” for ejecting ink droplets from each nozzle of the print head 20 and “fine vibration bit data” for giving a slight vibration to the meniscus. The dot pattern data composed of the minute vibration data is developed. The ROM 5 stores various control routines executed by the control unit 6, font data, graphic functions, various procedures, and the like.

  The control unit 6 as “data generation means” reads the print data in the reception buffer 4A, converts it into an intermediate code, and stores this intermediate code data in the intermediate buffer 4B. Next, the control unit 6 analyzes the intermediate code data read from the intermediate buffer 4B, and expands the intermediate code data into dot pattern data by referring to the font data and graphic functions in the ROM 5. Here, as the internal function, the control unit 6 analyzes the print data and detects the operating state of each nozzle, and the fine vibration to apply the fine vibration at a predetermined position according to the analysis result. And a micro-vibration data setting unit 12 for setting data. That is, for each main scan, the control unit 6 analyzes in advance the dot formation positions formed by the respective color nozzles, and determines the fine vibration to be applied to the meniscus of each nozzle based on the dot formation state of each color. . The dot pattern data generated by the control unit 6 is set with ejection data and microvibration data for each printing cycle, and is stored in the output buffer 4C.

  When dot pattern data corresponding to one line of the print head 20 is obtained, the dot pattern data for one line is serially transmitted to the print head 20 via the I / F 9. When dot pattern data for one line is output from the output buffer 4C, the contents of the intermediate buffer 4B are erased and the next intermediate code conversion is performed.

  The print engine 2 includes a print head 20, a paper feed mechanism 21, and a carriage mechanism 22. The paper feed mechanism 21 includes a paper feed motor, a paper feed roller, and the like, and sequentially feeds a print recording medium such as recording paper to perform sub-scanning. The carriage mechanism 22 includes a carriage on which the print head 20 is mounted and a carriage motor that travels the carriage via a timing belt or the like, and causes the print head 20 to perform main scanning.

  The print head 20 has a large number of nozzles arranged in the sub-scanning direction, and ejects ink droplets from each nozzle at a predetermined timing. The print data developed into the dot pattern data is serially transmitted from the I / F 9 to the shift register 23 in synchronization with the clock signal (CK) from the oscillation circuit 7. The serially transferred print data (SI) is once latched by the latch circuit 24. The latched print data is boosted to a voltage that can drive the switch circuit 26 by a level shifter 25 that is a voltage amplifier, for example, a predetermined voltage value of about several tens of volts. The print data boosted to a predetermined voltage value is given to a switch circuit 26 as “switch means”. A drive signal (COM) from the drive signal generation circuit 8 is applied to the input side of the switch circuit 26, and a piezoelectric vibrator 27 as a “pressure generation element” is connected to the output side of the switch circuit 26. ing.

  The print data controls the operation of the switch circuit 26. For example, during a period when the data applied to the switch circuit 26 is “1”, a drive signal is applied to the piezoelectric vibrator 27, and the piezoelectric vibrator expands and contracts in accordance with the drive signal. On the other hand, while the data applied to the switch circuit 26 is “0”, the supply of the drive signal to the piezoelectric vibrator 27 is interrupted.

1-2 Specific Configuration of Print Head FIG. 2 is a circuit diagram specifically showing the configuration of the print head 20. The shift register circuit 13, the latch circuit 24, the level shifter 25, the switch circuit 26, and the piezoelectric vibrator 27 in FIG. 1 are elements 23A to 23N, 24A to 24N, 25A to 25N, and 26A corresponding to the nozzles of the print head 20, respectively. To 26N and 27A to 27N. The print data is composed of 2-bit data for each nozzle, such as (10), (01), and the like. The upper bits are ejection data for ejecting ink droplets, and the lower bits are microvibration data for microvibrating the meniscus. Then, bit data of each digit for all the nozzles is input to the shift registers 23A to 23N within one printing cycle.

  That is, after the most significant bit data for all nozzles is serially transferred to the shift registers 23A to 23N, the upper bit data for all nozzles is latched by the latch elements 24A to 24N. With this latch, the lower bit data for all nozzles is then transferred to the shift registers 23A to 23N.

  For example, when the bit data applied to the switch elements 26A to 26N configured as analog switches is “1”, the drive signal (COM) is directly applied to the piezoelectric vibrators 27A to 27N, and the piezoelectric vibrators 27A to 27N are applied. 27N is displaced according to the signal waveform of the drive signal. Conversely, when the bit data applied to each switch element 26A to 26N is “0”, the drive signal to each piezoelectric vibrator 27A to 27N is cut off, and each piezoelectric vibrator 27A to 27N holds the previous charge. .

1-3 Example of Mechanical Structure of Print Head FIG. 3 shows an example of the mechanical structure of the print head 20. The substrate unit 31 is configured by sandwiching a flow path forming plate 34 between a nozzle plate 32 in which nozzle holes 32A are formed and a diaphragm 33 in which island portions 33A are formed. In the flow path forming plate 34, an ink chamber 35, an ink supply port 36, and a pressure generating chamber 37 are formed.

  A storage chamber 39 is formed in the base 38, and a piezoelectric vibrator 27 (exactly one of the piezoelectric vibrators 27 </ b> A to 27 </ b> N) is attached in the storage chamber 39. The piezoelectric vibrator 27 is fixed via a fixed substrate 40 so that the tip of the piezoelectric vibrator 27 is in contact with the island portion 33 </ b> A of the vibration plate 33. Here, for example, PZT having a longitudinal vibration lateral effect is used for the piezoelectric vibrator 27, and contracts when charged and expands when discharged. Charging / discharging of the piezoelectric vibrator 27 is performed via the lead wire 41.

  The piezoelectric vibrator 27 is not limited to the longitudinal vibration / lateral effect PZT but may be a flexural vibration type PZT. In this case, it expands when charged and shrinks when discharged. Further, the pressure generating element is not limited to the piezoelectric vibrator, and other elements such as a magnetostrictive element may be used. Alternatively, the ink may be heated by a heat source such as a heater, and the pressure may be changed by bubbles generated by the heating. In short, any element that causes a pressure fluctuation in the pressure generating chamber 37 according to a signal given from the outside can be used.

  When the piezoelectric vibrator 27 is charged, the piezoelectric vibrator 27 contracts and the pressure generation chamber 37 expands, the pressure in the pressure generation chamber 37 decreases, and ink flows from the ink chamber 35 into the pressure generation chamber 37. When the piezoelectric vibrator 27 is discharged, the piezoelectric vibrator 27 expands and the pressure generating chamber 37 contracts, the pressure in the pressure generating chamber 37 rises, and the ink in the pressure generating chamber 37 passes through the nozzle hole 32A. It is discharged outside.

1-4 Relationship between Drive Signal and Meniscus Change FIG. 4 shows the relationship between the drive signal input to the piezoelectric vibrator 27 and the state of the meniscus changed by the drive signal. As shown in the uppermost stage in FIG. 4, the drive signal output from the drive signal generation circuit 8 includes a print pulse as a “print drive signal” and a “fine vibration pulse” as a “fine vibration drive signal”. It is configured.

  The print pulse rises from the intermediate potential Vm to the maximum potential VPM, maintains the maximum potential VPM for a short time, then decreases to the minimum potential VL, maintains the minimum potential VL for a short time, and then returns to the intermediate potential Vm again. It has become. In order to prevent polarization inversion of the piezoelectric vibrator 27, the lowest potential VL is preferably set to be the same as the ground level or a positive potential. Further, it is preferable to set the voltage gradient (VPM → VL) at the time of discharging to be larger than the voltage gradient (Vm → VPM) at the time of charging. When such a printing pulse is input to the piezoelectric vibrator 27, the piezoelectric vibrator 27 expands and contracts according to the pulse shape as shown on the left side of the lowermost stage in FIG. It is discharged from.

  On the other hand, the fine vibration pulse has a shape that rises from the intermediate potential Vm to the second maximum potential VPS, maintains the second maximum potential VPS for a short time, and then returns to the intermediate potential Vm. Here, the second maximum potential VPS is set to be lower than the maximum potential VPM of the printing pulse, and the voltage gradient during charging (Vm → VPS) and the voltage gradient during discharging (VPS → Vm) Are set to be substantially the same. When such a fine vibration pulse is input to the piezoelectric vibrator 27, as shown on the right side of the lowermost stage in FIG. 4, the meniscus is slightly pulled into the nozzle hole 32A and then pushed back, and no ink droplet is ejected. That is, since the micro vibration pulse is for charging / discharging the piezoelectric vibrator 27 shallowly, the pressure change in the pressure generating chamber 37 becomes relatively gradual and causes the meniscus to vibrate slightly without ejecting ink droplets. Can do. Thereby, the ink in the vicinity of the nozzle hole 32A is replaced with new ink, and an increase in ink viscosity is prevented.

  Next, the transfer timing of the print data (dot pattern data) will be described. By synchronizing the generation timing of the printing pulse and the micro-vibration pulse with the transfer timing of the ejection data and the micro-vibration data, the ink droplets are discharged at a desired position. It can be discharged or given a slight vibration. That is, at the time before the printing pulse is generated, the upper bit data (ejection data) D1 of each nozzle of each color is transferred to the print head 20 to be latched, and the switch circuit 26 is activated when the printing pulse starts. As a result, ejection data of “1” or “0” is input to the switch circuit 26 corresponding to each nozzle, ink droplets are ejected from the nozzles to be ejected, and nozzles that should not be ejected are placed in a resting state. . Similarly, before the fine vibration pulse is generated, the lower bit data (fine vibration data) D2 of each nozzle of each color is transferred and latched, and the fine vibration data is input to the switch circuit 26 simultaneously with the start of the generation of the fine vibration pulse. To operate. As a result, fine vibration is performed in the nozzles that are given “1” as the fine vibration data, and fine vibrations are not performed in the nozzles that are given “0” as the fine vibration data.

  As shown in FIG. 5, when the data of one printing cycle is (11), both the printing pulse and the fine vibration pulse are input to the piezoelectric vibrator 27. In this printing cycle, ink droplets are ejected from the nozzles, and a slight vibration is applied to the meniscus. When the data of one printing cycle is (10), only the printing pulse is input to the piezoelectric vibrator 27, so that ink droplets are ejected but no fine vibration is performed. Similarly, when data (01) is input, only slight vibration is performed, and when data (00) is input, neither ink droplet ejection nor slight vibration is performed.

1-5 Operation Next, the operation of the present embodiment will be described with reference to FIGS. The flowchart of FIG. 6 shows a fine vibration setting process for giving a fine vibration to the meniscus of each nozzle based on the print data for each line.

  First, in step (hereinafter abbreviated as “S”) 1, the first nozzle, that is, the first line is set, and raster image data of the set line is read (S2). Next, by analyzing the image data for one line, it is detected in which printing cycle the print dots are formed, and fine vibration data is set based on the analysis result (S3). That is, the minute vibration data is set so that the minute vibration is not applied in the predetermined period immediately before the formation of the printing dots, and the minute vibration is performed in the other printing periods. The setting of the minute vibration data in S3 will be described later with reference to FIG.

  Then, it is determined whether or not fine vibration on / off has been set for all nozzles (S4). If the setting has not been completed for all nozzles, the next nozzle number is set (S5), and the process returns to S2. If the fine vibration data is set for all the nozzles by repeating S2 to S5, the process is terminated. Thereby, a predetermined fine vibration is given to each nozzle for each main scanning.

  Next, the flowchart of FIG. 7 shows a specific example of the data setting process shown as S3 in FIG.

  First, the print buffer for one line is Dnx (where x = 1, 2, 3,... M (m is an even number)). Discharge data for discharging ink droplets is stored at a place where x is an odd number, and fine vibration data is stored at a place where x is an even number. When the data Dnx is “1”, it indicates driving, and when it is “0”, it indicates non-driving. Referring to FIG. 8 first, FIG. 8 schematically shows a print buffer of three nozzles # 1 to # 3. Each print buffer stores data from 1 to 34. In this case, m = 34. The odd-numbered data 1, 3, 5, 7,... 33 stores ejection data, and the even-numbered data 2, 4, 6, 8,. The A black circle indicates that the data is “1”, and a white circle indicates that the data is “0”. Therefore, for example, the discharge data of x = 3 in nozzle number # 1 is set to “1”, and the fine vibration data of x = 34 is set to “0”.

  Returning to FIG. First, the data reading position is set to x = m−1, the discharge flag F indicating that the discharge data is set to “1” is set to 0, and 3 is set to a period T1 for prohibiting slight vibration. Set (S11). Next, it is determined whether or not the data reading position x is less than 1, that is, whether or not there is no discharge data to be read (S12). Here, it should be noted that this processing is performed from the last data in the print buffer. It should be noted that fine vibration data is set by analyzing sequentially from the last discharge data to the first discharge data.

  Next, the data Dnx is read from the print buffer (S13), and it is determined whether or not “1” is set in the data Dnx (S14). When “1” is set in the read discharge data Dnx, the discharge flag F is set to 1, and the counter C is initialized and set to 1 (S15), and the process proceeds to S16. If “0” is set in the ejection data Dnx, S15 is skipped and the process proceeds to S16.

  In S16, it is determined whether or not the discharge flag F is set to “0”. If the discharge flag F is set to “0”, the process proceeds to S18 described later, and the discharge flag F is set to “1”. If set, the process proceeds to S17. In S17, it is determined whether or not the value of the counter C exceeds the period T1 (= 3). Until the value of the counter C becomes “4” and exceeds the period T1, the data located immediately before the ejection data Dnx being inspected, that is, the minute vibration data Dn (x−1) is “0” in S19. Is set. On the other hand, when the value of the counter C exceeds the period T1, “1” is set to the minute vibration data Dn (x−1) (S18). After “1” or “0” is set to the micro vibration data in S18 or S19, the value of the counter C is advanced by “1”, and the data reading position x is decreased by “2”, and the next ejection data is set. Prepare for reading (S20).

  In other words, in the flowchart shown in FIG. 7, when the analysis is performed from the last ejection data in the print buffer and “1” is set in the ejection data, the three printing cycles that are immediately before the ejection printing cycle are fine. The fine vibration data is set to “0” so as not to vibrate (S14: YES, S15, S16: NO, S17: NO, S19, S20). On the other hand, when “0” is set in the ejection data, “1” is set in the micro vibration data located immediately before the ejection data (S14: N0, S16: YES, S18, S20).

  FIG. 8 is an explanatory diagram showing a state in which microvibration data is set, and 17 print cycles are shown. For example, “1” is set in the last ejection data Dn33 of the nozzle number # 1. Accordingly, “0” is set in the fine vibration data Dn32, Dn30, and Dn28 in the three printing cycles immediately before Dn33. Then, “1” is set in each micro-vibration data Dn26, Dn24, Dn22, Dn20, Dn18 until the next inspection of Dn17 where the ejection data is “1”.

  Here, “1” is set in both of the two continuous discharge data Dn17 and Dn15 in the discharge data. If “1” is set only in the discharge data Dn17 and “0” is set in the data Dn15, “1” is set in the micro vibration data Dn10 located four print cycles before the discharge data Dn17. However, since “1” is also set in the discharge data Dn15, fine vibration is prohibited in Dn16, Dn14, Dn12, and Dn10.

  In nozzle number # 2, since “1” is set only for the discharge data after Dn19, “1” is set for each fine vibration data from the fine vibration data Dn12 four print cycles before the discharge data Dn19. Is done. Accordingly, in the period before the formation of the print dots, the # 2 nozzle is slightly vibrated, and the fine vibration is prohibited in the three printing cycles immediately before the ink droplets are ejected. In nozzle number # 3, since the minute vibration prohibition sections defined in period T1 overlap, as a result, fine vibration is not performed in nozzle # 3.

According to the present embodiment configured as described above, the following effects can be obtained.
First, the dot pattern data to be supplied to the print head 20 is generated by analyzing the print data and setting the fine vibration data at a predetermined position in advance. Thus, it is possible to apply a minute vibration as much as necessary to the meniscus of each nozzle. That is, according to the present invention, fine vibration is given to each nozzle in consideration of not only a specific printing dot but also the formation state of all the printing dots in one line. Accordingly, it is possible to prevent an increase in ink viscosity, stabilize the flight of ink droplets, and maintain high print quality. Further, since the increase in the ink viscosity can be delayed by giving an appropriate fine vibration, the flushing interval can be set long. Therefore, the amount of ink discarded by flushing can be reduced and ink can be consumed without waste, and the running cost of printing can be reduced.

  Secondly, in the three printing cycles immediately before ejecting ink droplets, fine vibration is not given, so that the ink droplets can be ejected after the meniscus is sufficiently settled, and the ink droplets are kept in good flight. Can do. That is, when the meniscus is finely vibrated, it depends on the magnitude of the vibration, but it takes time for the fine vibration to attenuate and the meniscus state to settle. Therefore, if ink droplets are ejected before the meniscus settles, the weight, shape, flight path, etc. of the ink droplets may fluctuate, and the landing position, print dot diameter, etc. may become unstable. However, in the present embodiment, fine vibration is not performed in the three printing cycles immediately before the ink droplets are ejected, so that the ink droplets can be ejected after the meniscus is sufficiently settled.

  Thirdly, since fine vibration is performed during printing, the printing time is not reduced and the printing time can be shortened.

  Next, a second embodiment of the present invention will be described based on FIG. 9 and FIG. In the following embodiments, the same components as those in the first embodiment described above are denoted by the same reference numerals, and description thereof is omitted. A feature of the present embodiment is that, as the second pattern for setting the micro-vibration data, the micro-vibration is not performed in the first period immediately before ejecting the ink droplet, and the micro-vibration is performed in the second period immediately before the first period. It is in the point which made it vibrate.

  FIG. 9 is a flowchart of data setting processing according to the present embodiment. This processing includes S12 to S15 and S18 to S20 shown in FIG. 7, and S31 to S33 are unique steps.

  In S31 for initialization, the data reading position x is set to m−1 and the discharge flag F is set to “0”. Further, in S31, the value of the first period T1 is set to “3”, and the value of the second period T2 is set to “5”. As shown in FIG. 10, the first period T1 is a parameter that defines a period during which fine vibration is prohibited, and “0” is set in the fine vibration data for three printing periods positioned immediately before the ejection printing period. The The second period T2 is a parameter that defines a period during which the minute vibration is applied, and “1” is set in the minute vibration data for five printing cycles located immediately before the first period T1. That is, in the present embodiment, before the printing cycle for ejecting ink droplets, a fine vibration pattern is set that “stops micro-vibration three times continuously after applying micro-vibration five times continuously”. .

  Now, after performing initialization (S31), the process proceeds to S32 through S12 to S14. In S32, it is determined whether or not the discharge flag F is set to “0”. Moving to S19, “0” is set to the fine vibration data Dn (x−1) located immediately before the ejection data Dnx related to the inspection. In other words, in the present embodiment, the fine vibration data is not set to “1” unless the ejection data in which “1” is set is detected.

  When F = 1, it is determined as “NO” in S32, and in S33, it is determined whether or not the value of the counter C exceeds T1 and is equal to or smaller than the total value of T1 + T2 (T1 + T2 ≧ C). > T1). Therefore, until the value of the counter C reaches “4”, it is determined as “NO” in S33, and “0” is set in the minute vibration data in S19. While the value of the counter C is in the range of “4” to “8”, “YES” is determined in S33, and “1” is set in the micro vibration data in S18. If the value of the counter C is equal to or greater than “9”, “NO” is determined in S33, and “0” is set in the minute vibration data in S19.

  FIG. 9 is an explanatory diagram showing a setting state of micro vibration data according to the present embodiment. Focusing on the nozzle # 1, since “1” is set in the discharge data Dn17, in the three printing periods belonging to the first period T1 immediately before the discharge data Dn17, the fine vibration data Dn16, Dn14, and Dn12 are “ 0 "is set. Then, in the five printing cycles belonging to the second period T2 immediately before the first period T1, the fine vibration data Dn10, Dn8, Dn6, Dn4, Dn2 are set to “1”. Next, since the discharge data Dn27 is set to “1” for the nozzle # 2, “0” is set to the three micro-vibration data Dn26, Dn24, and Dn22 belonging to the first period. “1” is set in each of the three micro-vibration data Dn20, Dn18, and Dn16 belonging to T2a. Here, the reason why the second period T2a is as short as three printing periods instead of the standard five printing periods is set to “1” in the ejection data Dn15, and is limited by the first period T1 set for the ejection data Dn15. It is for receiving. Further, as shown in the nozzle # 3, the fine vibration is performed for five printing cycles belonging to the second period T2, and the fine vibration is not performed in the other printing cycles (Dn10, Dn8, Dn6, Dn4, Dn2). = 0). This is different from the first embodiment.

  Also in the present embodiment configured as described above, the same effects as those of the first embodiment described above can be obtained. In addition to this, in the present embodiment, the fine vibration is not performed in the first period T1 immediately before ejecting the ink droplets, and the second period T2 immediately before the first period T1 is performed. Without giving too much fine vibration, it is possible to efficiently give fine vibration to prevent an increase in ink viscosity and to reduce power consumption.

  Next, a third embodiment of the present invention will be described with reference to FIGS. A feature of the present embodiment is that, as in the second embodiment, slight vibration is performed in the acceleration travel range from the standby position to the start position of the print area.

  FIG. 11 shows a data setting process according to the present embodiment, and this process includes all steps shown in FIG. 9 except for S12. This embodiment is different from the second embodiment in that S41 is adopted instead of S12. In the present embodiment, the print buffer is expanded so as to cover the acceleration traveling area where the carriage travels at an accelerated speed. That is, when the data position related to the start point of the print area is “1”, the print buffer is expanded so that the data can be stored up to a set reference value of about −100, for example. Therefore, in S41, the data Dnx is read from the print buffer until the set reference value SP set in the acceleration travel area before the start point of the print area is reached.

  FIG. 12 is an explanatory diagram showing the setting state of the micro vibration data according to the present embodiment. As shown in the figure, the print buffer is expanded before the start position of the print area. In addition, since printing is not performed in the acceleration travel area, a cross mark is given to the ejection data. In addition, the signs of the data reading positions 1 to 9 shown in the acceleration region are all negative.

  As shown in the # 1 nozzle, when printing dots are formed from the start position (x = 1) of the printing area (Dn1 = 1), the first period T1 in which no fine vibration is performed and the second period T2 in which the fine vibration is performed. Both belong to the carriage acceleration travel area. Therefore, before the print head 20 reaches the print start position, an appropriate fine vibration is already given to the corresponding nozzle. As shown in the # 2 nozzle, depending on the position at which the first print dot is formed, part or all of the first period T1 belongs to the constant speed running area (printing area), and as shown in the # 3 nozzle. In addition, a part of the second period T2 may belong to the constant speed traveling region. In any case, in the constant speed traveling region, as in the second embodiment, the slight vibration is not performed before the three printing cycles immediately before the ink droplets are ejected, and the minute vibration is performed at the five preceding printing cycles. Is done.

  Even in the present embodiment configured as described above, the fine vibration is prohibited immediately before printing and the fine vibration is performed only for the predetermined period T2, so that the ink viscosity is prevented from increasing and the ink is kept waiting for the meniscus to settle. Drops can be ejected, and the same effects as in the second embodiment described above can be obtained. In addition, in the present embodiment, since the print head 20 can give an appropriate fine vibration before reaching the start position of the print area, the ink viscosity can be obtained even when printing is performed from the start position of the print area. Can be prevented and the flight of ink droplets can be stabilized.

  Next, a fourth embodiment of the present invention will be described with reference to FIGS. A feature of the present embodiment is that a minute vibration is given to the meniscus of the nozzle when a predetermined time elapses after the ink droplet is ejected.

  The flowchart in FIG. 13 shows a data setting process according to the present embodiment. This process is different from the above processes in that the ejection data is read and analyzed from the head of the print buffer. Therefore, in S51 for initialization, the data reading position x is set to “1”. In S51, the discharge flag F is set to “0”, the first period T3 is set to “3”, and the second period T4 is set to “5”. In S52, it is determined whether or not the data reading position x has exceeded “m−1”, that is, whether or not the final ejection data has been read. In this way, in this process, reading is sequentially performed from the first discharge data to the final discharge data in the print buffer.

  If the value of the read ejection data Dnx is “0”, “YES” is determined in S32, the process proceeds to S19, and the data for fine vibration is set to “0”. Then, the value of the counter C is increased by “1” and the data read position x is increased by “2” to prepare for the next data read (S56).

  When the value of the read ejection data Dnx is “1”, the value of the counter C is set to “1”, and the ejection flag F is set to “1” (S15). Then, “NO” is determined in S32, and the process proceeds to S53, in which it is determined whether or not the value of the counter C is equal to or smaller than the total value of the first period T3 and the second period T4. When the value of the counter C is equal to or smaller than T3 + T4, the process proceeds to S54, and it is determined whether or not the value of the counter C is larger than the first period T3. If the value of the counter C is equal to or shorter than the first period T3, it is determined as “NO” in S54 and the process proceeds to S19. Therefore, the minute vibration data is set to “0” in the first period T3 immediately after the ink droplet is ejected. It is set and does not vibrate slightly.

  On the other hand, when the value of the counter C exceeds the first period T3, it is determined as “YES” in S54 and the process proceeds to S18. Therefore, the minute vibration data is set to “1” immediately after the end of the first period T3. The Until the value of the counter C exceeds the total value of the first period T3 and the second period T4, it is determined as “YES” in S53 and S54, and the minute vibration data is set to “1”. When the value of the counter C exceeds T3 + T4, it is determined as “NO” in S53, and the value of the counter C is reset to “1” (S55).

  Therefore, as shown in the explanatory diagram of FIG. 14, in this process, when a nozzle that has paused for the first period T3 or more after ink droplet ejection is detected, a slight vibration is applied only during the second period T4 to increase the ink viscosity. Is preventing. As indicated by the nozzle # 1, after the first ink droplet is ejected at Dn3, the microvibration data is "1" for the printing period belonging to the second period T4 after the printing period belonging to the first period T3 has elapsed. "Is set. Thereafter, the pattern in which the minute vibration is stopped only during the first period T3 and the minute vibration is performed only during the second period T4 is periodically repeated. Further, as shown by the nozzle # 2, the fine vibration data is not set to “1” unless the first ejection is detected.

  Also in the present embodiment configured as described above, the same effects as those of the first embodiment described above can be obtained. In addition to this, in the present embodiment, when there is a nozzle that pauses for a predetermined period T3 after ejecting ink droplets, a minute vibration is given only during the period T4. Thus, increase in ink viscosity can be prevented. That is, immediately after the ink droplet is ejected, the ink in the vicinity of the nozzle hole has already been replaced with a new ink by ejecting the ink droplet, so that it is not necessary to give a slight vibration. Therefore, in this embodiment, it is possible to prevent useless microvibration immediately after ejection, and to give necessary microvibration when a predetermined period T3 elapses and the influence of volatilization of a solvent or the like can occur. it can.

  Next, a fifth embodiment of the present invention will be described with reference to FIGS. The feature of this embodiment is that the idle nozzle is periodically subjected to fine vibration.

  FIG. 15 is a flowchart of data setting processing according to this embodiment. First, in S61, it is determined whether or not there is data for ejecting ink droplets in one dot line, that is, whether or not there is ejection data for which “1” is set. If there is even one ejection data set with “1”, it is not an idle nozzle, and the process is terminated.

  If “YES” is determined in S61, the parameter is initialized in S62 because it is an idle nozzle that does not perform printing. That is, the data reading position x = 1, the counter C = 1, the first period T3 = 3, and the second period T4 = 5 are set. Then, the process is started from the first ejection data to the final ejection data (S52), and the pattern in which the minute vibration is stopped only for the first period T3 and then the minute vibration is given only for the second period T4 is periodically repeated. .

  As shown in the explanatory diagram of FIG. 16, the idle nozzles # 1 and # 3 that do not discharge ink droplets once in the main scanning are periodically given a minute vibration only during the second period T4. Ink viscosity is prevented from increasing.

  Next, a sixth embodiment of the present invention will be described with reference to FIGS. The feature of this embodiment is that the period during which the minute vibration is performed and the ratio at which the minute vibration is performed can be variably set based on the environmental temperature (ambient temperature).

  FIG. 17 shows a flowchart of the fine vibration setting process according to this embodiment, and this process includes all S1 to S5 shown in FIG. However, all the patterns described in the above embodiments can be appropriately adopted as the setting pattern of the micro vibration data executed in S3. In addition to this, in this process, first, the environmental temperature is detected based on a signal from a temperature sensor provided on the print head 20 or the main control board (S71), and then the detected environmental temperature is reached. Based on the map described later, a ratio for performing fine vibration (S72) and a period for performing fine vibration (S73) are set.

  FIG. 18 is an explanatory diagram showing the ratio α for performing minute vibration, the period Ts for performing minute vibration, and the like. 18A and 18B show only micro vibration data. As shown in FIG. 18 (a), the ratio α indicates the ratio at which the minute vibration is applied during the minute vibration period Ts. When the ratio α = 100%, “1” is set in all the minute vibration data. . When the ratio α = 50%, “1” is set in the minute vibration data every other piece.

  As shown in FIG. 18B, the minute vibration period Ts defines a period during which the minute vibration is performed. As shown in FIG. 18C, for example, if the micro-vibration period Ts = 100 and the ratio α = 100%, “1” is set in all micro-vibration data in 100 continuous printing cycles. become. Further, for example, assuming that the minute vibration period Ts = 60 and the ratio α = 50%, “1” is set to every other minute vibration data in 60 consecutive printing cycles.

  FIG. 19 shows a ratio map for setting the ratio α and a period map for setting the fine vibration period Ts. As shown in FIG. 19A, the ratio map stores characteristics such that the ratio α decreases stepwise as the temperature increases. Similarly, as shown in FIG. 19B, the period map stores a characteristic that the micro-vibration period Ts decreases stepwise as the temperature increases. Note that the shape of the characteristic line is not limited to a stepped shape. Linear or curved characteristics may be used. In FIG. 19, α1 is a ratio at low temperature, α2 is a ratio at normal temperature, α3 is a ratio at high temperature, Ts1 is a microvibration period at low temperature, Ts2 is a microvibration period at normal temperature, and Ts3 is high temperature. Although it can be taken as a minute vibration period of time, it is not limited to this. This is because the ratio at low temperature may be 100%.

  FIG. 20 shows the setting state of the micro-vibration data according to the present embodiment. At a low temperature, the micro-vibration period Ts is set longer than the normal time, and the ratio α is set larger than the normal value. Therefore, a slight vibration is applied to the meniscus for a long period, and an increase in ink viscosity is prevented. At a high temperature, the fine vibration period Ts is set shorter than the normal time, and the ratio α is set smaller than the normal time. Therefore, the opportunity to be given a slight vibration is reduced.

  According to the present embodiment, since the fine vibration period Ts and the ratio α are set based on the environmental temperature, appropriate fine vibration according to the temperature can be given, and an increase in ink viscosity can be prevented. . For example, it is considered that the volatilization of the solvent is promoted at a high temperature due to the saturation vapor pressure, etc., but the volatilization of the solvent is promoted at a high temperature if a slight vibration is given at the same rate for the same period as the normal time. This may increase the ink viscosity. On the other hand, in the present embodiment, since the opportunity to give fine vibration according to the temperature is adjusted, the extra fine vibration is not performed, and the ink viscosity is prevented from increasing and the ink droplet flying is stabilized. be able to.

  Next, a seventh embodiment of the present invention will be described with reference to FIGS. The feature of this embodiment is that the fine vibration period Ts and the ratio α are set based on the ink viscosity in the ink cartridge.

  FIG. 21 shows a flowchart of the fine vibration setting process according to the present embodiment. In this process, S81 to S83 are adopted instead of S71 to S73 in FIG. That is, first, the ink viscosity in the ink cartridge is detected (S81), and a ratio α (S82) and a fine vibration period Ts (S83) are set by referring to a map to be described later based on the ink viscosity. .

  FIG. 22 is an explanatory diagram showing a viscosity map, a ratio map, and a period map for setting the viscosity. Although the ink cartridge has water vapor permeability, the ink viscosity gradually increases as time elapses after a new ink cartridge is mounted, although it varies depending on the material and the like. Therefore, the viscosity map shown in FIG. 22A can be created by obtaining the relationship between the elapsed time after the mounting and the ink viscosity in the ink cartridge in advance through experiments or the like. The current ink viscosity can be estimated by referring to the viscosity map based on the elapsed time since the ink cartridge was mounted.

  As shown in FIG. 22B, the ratio map is stored as a characteristic in which the value gradually increases as the mounting time of the ink cartridge becomes longer. The period map is stored as a characteristic such that the micro-vibration period Ts increases as the mounting time of the ink cartridge becomes longer as shown in FIG. Therefore, as the ink viscosity increases, the fine vibration period Ts and the ratio α increase, and the opportunity to give the fine vibration increases.

  According to the present embodiment, since the fine vibration period Ts and the ratio α that gives the fine vibration can be set based on the ink viscosity in the ink cartridge, the same effect as in the sixth embodiment can be obtained.

  Next, an eighth embodiment of the present invention will be described with reference to FIGS. The feature of the present embodiment is that the fine vibration period Ts and the ratio α are set according to the solid content concentration while paying attention to the solid content concentration of the ink.

  FIG. 23 is a flowchart showing the fine vibration setting process according to the present embodiment. In this process, S91 to S93 are adopted instead of S81 to S83 shown in FIG. That is, the solid content concentration of each ink different depending on the ink color is detected (S91), and the ratio α (S92) and the fine vibration period Ts (S93) are referred to based on the detected solid content concentration. And are set respectively.

  FIG. 24 is an explanatory diagram showing each map. As shown in FIG. 24A, in the concentration map, the solid content concentration is divided into three stages of “high”, “medium”, and “low”, and ink colors belonging to the respective sections are stored in advance. . That is, black ink is included in high-density ink, cyan and magenta are included in medium-density ink, and yellow, light cyan, and light magenta are included in low-density ink. Light cyan and light magenta indicate lighter (brighter) colors than cyan and magenta. In a color ink jet printer, each color ink is ejected from a dedicated print head, so it can be understood that the solid content concentration is preset for each color head.

  As shown in FIG. 24B, the ratio map is stored as a characteristic such that the ratio α increases stepwise as the solid content concentration increases. As shown in FIG. 24C, the period map is stored as a characteristic such that the fine vibration period Ts increases stepwise as the solid content concentration increases. Therefore, as the solid content concentration of the ink increases, the fine vibration period Ts becomes longer and the ratio α increases, so that the opportunity for giving the fine vibration increases.

  In this embodiment configured as described above, the fine vibration period Ts and the ratio α are set according to the solid content concentration of the ink, so that an appropriate fine vibration according to the solid content concentration is given as shown in FIG. be able to. In addition, since the solid content concentration is determined in advance for each ink color, it is not necessary to provide a concentration sensor or the like, and without complicating the overall configuration, the increase in ink viscosity is prevented and the ink droplet flying is stabilized. , Useless flushing can be prevented.

  Next, a ninth embodiment of the present invention will be described with reference to FIGS. A feature of the present embodiment is that a plurality of setting patterns for micro-vibration data described in the respective embodiments are introduced.

  The flowchart of FIG. 26 shows the fine vibration setting process according to the present embodiment. In this process, the fine vibration data is set according to three patterns by analyzing the image data for one line. That is, in S101, as described in the fifth embodiment, when an idle nozzle is detected, the minute vibration data is periodically set to “1” (fourth pattern). In S102, as described in the fourth embodiment, when the time has elapsed for the first period T3 after ejection, the micro vibration data is set to “1” only for the second period T4 (third pattern). ). In S103, as described in the third embodiment, in consideration of the area where the print head 20 travels at an accelerated speed, fine vibration is not performed in the first period T1 immediately before ink droplets are ejected, and the first period T1. Micro-vibration data is set so as to perform micro-vibration only in the second period T2 immediately before (second pattern).

  FIG. 27 is an explanatory diagram showing the setting state of the fine vibration data according to the present embodiment. Since the nozzle # 1 is an idle nozzle, periodic fine vibration is given. In each of the nozzles # 2 and # 3, fine vibration is performed at a predetermined position by the second and third patterns. Therefore, in the present embodiment, appropriate fine vibration can be given in accordance with the operating state of each nozzle.

  Next, a tenth embodiment of the present invention will be described with reference to FIGS. In the present embodiment, as shown in the fine vibration setting process of FIG. 28, S104 is adopted instead of S103 in FIG. That is, in S104, as described in the first embodiment, the fine vibration data is set so that the fine vibration is performed except for the period T1 immediately before the ink droplet is ejected (first pattern). Thereby, the same effect as that of the ninth embodiment can be obtained.

  It should be noted that those skilled in the art can make various additions, changes, etc., or combine the embodiments within the scope of the gist of the invention described in the embodiments. For example, the values of the above-described periods T1 to T4 are all examples, and the present invention is not limited to this. However, it is possible to adopt each numerical value as a preferable example.

  Further, as in the first modification shown in FIG. 30, the printing drive signal may be composed of a plurality of drive pulses. The first pulse and the third pulse are for ejecting medium ink droplets, respectively, and the second pulse is for ejecting minute ink droplets. By appropriately selecting each pulse, four types of ink droplets can be ejected.

  Furthermore, as in the second modification shown in FIG. 31, some of the pulses can be inverted. In the present invention, it is obvious that drive signals other than those shown in each embodiment and each modification can be adopted.

  Further, the present invention can be realized by storing the program shown in each flowchart in a recording medium such as a memory and reading the program into a computer mounted on a printer.

Furthermore, based on each embodiment mentioned above, this invention can also be expressed as follows.
Expression 1. 4. The ink jet recording apparatus according to claim 2, wherein a predetermined period (or the first period) immediately before ejecting the ink droplets is before the pressure fluctuation caused by the slight vibration is attenuated. An ink jet recording apparatus that is set longer than the time required.
Expression 2. 8. The ink jet recording apparatus according to claim 7, wherein the period for setting the bit data for fine vibration becomes shorter as the environmental temperature becomes higher.
Expression 3. 8. The ink jet recording apparatus according to claim 7, wherein the predetermined ratio is set lower as the environmental temperature becomes higher.
Expression 4. 9. The ink jet recording apparatus according to claim 8, wherein a period for setting the fine vibration bit data is set longer as the ink viscosity increases.
Expression 5. The ink jet recording apparatus according to claim 8, wherein the predetermined ratio is set higher as the ink viscosity increases.
Expression 6. The ink jet recording apparatus according to claim 11, wherein the period for setting the bit data for fine vibration becomes longer as the solid content concentration of the ink increases.
Expression 7. The ink jet recording apparatus according to claim 11, wherein the predetermined ratio is set higher as the solid content concentration of the ink increases.

1 is a configuration explanatory diagram illustrating an overall configuration of an inkjet printer to which an embodiment of the present invention is applied. FIG. 3 is a circuit diagram illustrating a main part of a print head driving circuit. FIG. 3 is an explanatory diagram illustrating a mechanical structure of a print head. It is explanatory drawing which shows the relationship between the drive signal used for the 1st Embodiment of this invention, meniscus, etc. FIG. It is explanatory drawing which shows the state which selects a pulse with the data in one printing period. It is a flowchart which shows a fine vibration setting process. It is a flowchart of the data setting process which sets micro vibration data. It is explanatory drawing which shows the setting state of micro vibration data. It is a flowchart of the data setting process which concerns on the 2nd Embodiment of this invention. It is explanatory drawing which shows the setting state of micro vibration data. It is a flowchart of the data setting process which concerns on the 3rd Embodiment of this invention. It is explanatory drawing which shows the setting state of micro vibration data. It is a flowchart of the data setting process which concerns on the 4th Embodiment of this invention. It is explanatory drawing which shows the setting state of micro vibration data. It is a flowchart of the data setting process which concerns on the 5th Embodiment of this invention. It is explanatory drawing which shows the setting state of micro vibration data. It is a flowchart of the fine vibration setting process which concerns on the 6th Embodiment of this invention. It is explanatory drawing which shows the relationship between a slight vibration period and a ratio. It is explanatory drawing which shows a ratio map and a period map, respectively. It is explanatory drawing which shows the setting state of micro vibration data. It is a flowchart of the fine vibration setting process which concerns on the 7th Embodiment of this invention. It is explanatory drawing which shows a viscosity map, a ratio map, and a period map, respectively. It is a flowchart of the fine vibration setting process which concerns on the 8th Embodiment of this invention. It is explanatory drawing which shows a density map, a ratio map, and a period map, respectively. It is explanatory drawing which shows the setting state of micro vibration data. It is a flowchart of the fine vibration setting process which concerns on the 9th Embodiment of this invention. It is explanatory drawing which shows the setting state of micro vibration data. It is a flowchart of the fine vibration setting process which concerns on the 10th Embodiment of this invention. It is explanatory drawing which shows the setting state of micro vibration data. It is explanatory drawing which shows the drive signal which concerns on the 1st modification of this invention. It is explanatory drawing which shows the drive signal which concerns on the 2nd modification of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Printer controller 2 Print engine 6 Control part 8 Drive signal generation circuit 11 Print data analysis part 12 Slight vibration data setting part 20 Print head 26 Switch circuit 27 Piezoelectric vibrator 32A Nozzle hole

Claims (10)

Inkjet recording that has a print head provided with a pressure generating element corresponding to each of a plurality of nozzles, and discharges ink droplets from each nozzle by operating each pressure generating element based on input data In the device
Drive signal generating means for generating a drive signal for printing for ejecting ink droplets and a drive signal for fine vibration for operating the pressure generating element to such an extent that ink droplets are not ejected;
Generate dot pattern data including bit data for printing for selecting the drive signal for printing and bit data for fine vibration for selecting the drive signal for fine vibration based on the input print data Data generation means for
Based on the dot pattern data input from the data generation means, the print drive signal and the fine vibration drive signal are periods that can form one print dot for the pressure generating element. Switch means capable of inputting within the printing cycle,
Said data generating means selects a predetermined pattern, wherein according to the discharge state of each nozzle to be analyzed on the basis of the print data, in accordance with the predetermined pattern, finely performed before each ejection data for ejecting ink An ink jet recording apparatus that generates the dot pattern data by setting the minute vibration bit data for vibration at a predetermined position. In the data generation means, a second pattern is set as the predetermined pattern,
In the second pattern, the fine vibration drive signal is not selected in the printing period in the first period immediately before ejecting the ink droplets, and the fine vibration is not used in the printing period in the second period immediately before the first period. 2. The ink jet recording apparatus according to claim 1, wherein the fine vibration bit data is set so as to select a drive signal at a predetermined ratio. The inkjet recording apparatus according to claim 2 , wherein the first period and the second period can be set also in an acceleration region where the print head is accelerated. Wherein at least one of the length and the predetermined ratio of the period for setting the micro-vibrating-bit data to select the micro-vibration drive signal, according to claim 2 or are variably set corresponding to the environmental temperature The ink jet recording apparatus according to claim 3 . Wherein at least one of the length and the predetermined ratio of the period for setting the micro-vibrating-bit data to select the micro-vibration drive signal, according to claim 2 or is variably set in accordance with the ink viscosity The ink jet recording apparatus according to claim 3 . The ink jet recording apparatus according to claim 5 , wherein the period for setting the fine vibration bit data is set longer as the elapsed time after the ink cartridge is mounted. The ink jet recording apparatus according to claim 5 , wherein the predetermined ratio is set to be higher as the elapsed time after the ink cartridge is installed becomes longer. At least one of the length of the period for setting the bit data for fine vibration and the predetermined ratio so as to select the drive signal for fine vibration is variably set according to the solid content concentration of the ink. The ink jet recording apparatus according to claim 2 or 3 . The pressure generating element, an ink jet recording apparatus according to any one of claims 1 to 8 is a piezoelectric vibrator. In an ink jet recording method of ejecting ink droplets from each nozzle by operating pressure generating elements provided corresponding to the plurality of nozzles,
Analyzing the discharge state of each nozzle based on the input print data,
Select a predetermined pattern based on the analyzed discharge state,
According to a predetermined pattern that the selected, by setting the micro-vibrating-bit data for a slight vibration performed before each ejection data for ejecting ink to a predetermined position, generates dot pattern data for printing output And
When the fine vibration bit data is set, an ink jet recording method is characterized in that a drive signal for fine vibration that does not eject ink droplets is input to the pressure generating element.

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