JP2007044878A - Liquid jet apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink-jet recorder, widely a liquid jet apparatus which can start a next printing period even in a state wherein a meniscus swells by ejection of ink droplets in the preceding printing period, and which can accordingly achieve speed-up of the recording action. <P>SOLUTION: The driving pulse generating means generates for every unit region of a medium to which a liquid is jetted, a driving pulse train on the basis of tone data for the subject unit region, an ejection drive signal, and information on whether or not the driving pulse train generated for the unit region one precedent of the subject unit region includes the last pulse waveform within one period of the ejection drive signal. A pressure variation means is driven on the basis of the driving pulse. One period of the ejection drive signal corresponds to one unit region of the medium. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a liquid ejecting apparatus that ejects liquid droplets from nozzle openings, and more particularly, to a liquid ejecting apparatus that can eject liquid drops from nozzle openings based on drive pulses.

  An ink jet recording apparatus (a type of liquid ejecting apparatus) such as an ink jet printer or an ink jet plotter moves a recording head (head member) along the main scanning direction and also transfers a recording paper (a type of liquid ejected medium) An image (character) is recorded on the recording paper by moving along the scanning direction and ejecting ink droplets from the nozzle openings of the recording head in conjunction with the movement. The ink droplets are ejected, for example, by expanding and contracting a pressure generating chamber that communicates with the nozzle opening.

  The expansion / contraction of the pressure generating chamber is performed using, for example, deformation of the piezoelectric vibrator. In such a recording head, the piezoelectric vibrator is deformed in accordance with the supplied driving pulse, thereby changing the volume of the pressure chamber, and this volume change causes a pressure fluctuation in the ink in the pressure chamber, and the nozzle opening. Ink droplets are ejected.

  In such a recording apparatus, a drive signal that is a periodic signal having a pulse waveform is generated. On the other hand, ejection data (gradation data) is transmitted to the recording head. Then, based on the transmitted ejection data, only a necessary pulse waveform is selected from the drive signal and supplied to the piezoelectric vibrator. That is, whether or not ink droplets are ejected from the nozzle openings is controlled by ejection data.

  Here, if ink droplets are ejected while the recording head is stationary, the ink droplets land at a position directly below the nozzle opening. However, in general, in order to perform high-speed recording, ink droplets are ejected while the recording head is moving. Thus, the ink droplets ejected from the moving recording head are subjected to inertia caused by the movement of the recording head and land at a position shifted from a position immediately below the nozzle opening at the time of ink droplet ejection.

The present inventor has already invented Japanese Patent Application No. 2001-65307 as a prior art in which the recording accuracy is improved in consideration of such deviation of the landing position (Japanese Patent Laid-Open No. 2002-264307). In the prior application, the present inventor paid attention to the deviation of the landing position, and for the purpose of remarkably improving the recording accuracy, the ink which is an actually measured value obtained corresponding to the characteristics of each ink and the piezoelectric vibrator of each nozzle opening. It has been proposed to adjust the phase of each drive pulse based on the droplet ejection speed.
JP 2002-264307 A

  However, the present inventor found that the ink characteristics and the ejection speed of the ink droplets obtained corresponding to the piezoelectric vibrators of the respective nozzle openings are ejected to the previous pixel (ejection in the previous printing cycle). It has been found that it changes depending on the state of. The inventor of the present invention has intensively studied the cause and analyzed as follows. That is, after the ink droplet is ejected, the meniscus at the nozzle opening after ejecting the ink droplet exhibits a vibration state as shown in FIG. Here, when the meniscus is swollen outside the nozzle opening (A region in FIG. 10), a large amount of ink droplets are ejected at a high speed when the next ink droplet ejection pressure is applied. In particular, when the pressure of the next ink droplet ejection is received when the first meniscus is expanded to the outside of the nozzle opening immediately after ejecting the ink droplet, a larger amount of ink droplet is ejected at a higher speed.

  In order to avoid such a phenomenon, it can be proposed that when the meniscus is swollen outside the nozzle opening (region A in FIG. 10), a signal for discharging the next ink droplet is not given. . However, if such a condition is imposed, a high-speed recording operation cannot be realized. In other words, in order to realize a high-speed recording operation, it is effective to start the next printing cycle even if there is a state where the meniscus is swollen.

  The present invention has been made in consideration of such points, and even in a state where the ink droplets are ejected and the meniscus is swollen in the previous printing cycle, the ink droplets are ejected excessively or excessively. It is an object of the present invention to provide an ink jet recording apparatus, broadly a liquid ejecting apparatus, which can start the next printing cycle while suppressing the discharge amount, and thereby realize a high speed recording operation.

  The present invention includes a head member having a nozzle opening, pressure changing means for changing the pressure of the liquid in the nozzle opening portion to discharge a liquid drop, and facing the nozzle opening of the head member and being substantially equidistant from the nozzle opening. An ejected medium holding unit that holds the liquid ejected medium so as to be separated; a moving mechanism that moves the head member relative to the liquid ejected medium; and an ejection drive signal that is a periodic signal having a plurality of pulse waveforms. For each unit area of the liquid ejection medium to be generated, the gradation data for the unit area, the ejection drive signal, and the unit area immediately before the unit area are generated. Drive pulse generation means for generating a drive pulse train based on information on whether or not the drive pulse train includes the last pulse waveform within one cycle of the ejection drive signal, and the drive pulse Includes a main control unit for driving the pressure change means based on the scan, and one period of the ejection driving signal, it is liquid-jet apparatus characterized correspond to one unit area of the liquid ejection target medium.

  According to the present invention, the drive pulse train is based on the information whether the drive pulse train generated for the previous unit region (for example, pixel) includes the last pulse waveform in one cycle of the ejection drive signal. Therefore, it is possible to realize generation of a driving pulse train in consideration of the residual vibration of the liquid meniscus of the nozzle opening that ejects the liquid droplet by the last pulse waveform.

  Here, the influence of the residual vibration of the liquid meniscus is considered to be large when ejecting liquid droplets of a relatively small size.

  For example, when the gradation data includes small dot data for forming small dots on the liquid ejection medium, and the gradation data for the unit area is the small dot data, the unit area At least the first pulse waveform of the drive pulse train generated by the drive pulse generator when the drive pulse train generated for the unit region immediately before the first drive pulse train includes the last pulse waveform within one cycle of the ejection drive signal is , At least the first drive pulse train generated by the drive pulse generator when the drive pulse train generated for the unit region immediately before the unit region does not include the last pulse waveform in one cycle of the ejection drive signal. It is preferable that the pulse waveform of FIG.

  The reason is as follows. That is, at the nozzle opening that ejects the liquid droplet by the last pulse waveform in one cycle of the ejection drive signal in the previous unit area, the ejection is performed for the current unit area due to the influence of the residual vibration of the liquid meniscus. There is a tendency that the speed of the liquid droplets is increased (this increases the landing speed). Therefore, it is extremely effective to cancel the tendency by shifting at least the first pulse waveform of the drive pulse train for the current unit region backward in time (thus delaying landing).

  For example, the ejection drive signal is a periodic signal having a plurality of pulse waveforms having the same shape within one period.

  More specifically, for example, the ejection drive signal is a periodic signal having five pulse waveforms having the same shape within one period. In this case, for example, the gradation data includes small dot data for forming small dots on the liquid ejection medium and minimal dot data for forming minimal dots on the liquid ejection medium. When the gradation data for the unit area is data for small dots, the drive pulse train generated for the unit area immediately before the unit area is the last pulse in one cycle of the ejection drive signal. In the case where the waveform is included, at least the first pulse waveform of the drive pulse train generated by the drive pulse generator means that the drive pulse train generated for the unit region immediately before the unit region is within one cycle of the ejection drive signal. In the case where the last pulse waveform is not included, at least the first pulse waveform of the drive pulse train generated by the drive pulse generation means is in a relationship shifted backward in time, Even when the gradation data for the unit region is the data for the minimum dot, the drive pulse train generated for the unit region immediately before the unit region has the last pulse waveform in one cycle of the ejection drive signal. In the case where it is included, at least the first pulse waveform of the drive pulse train generated by the drive pulse generator means that the drive pulse train generated for the unit region immediately before the unit region is the last in one cycle of the ejection drive signal. Preferably, at least the first pulse waveform of the drive pulse train generated by the drive pulse generation means is shifted backward in time when the pulse waveform is not included.

  More specifically, for example, when the gradation data for the unit area is small dot data, the drive pulse train generated for the unit area immediately before the unit area is one of the ejection drive signals. The drive pulse train generated by the drive pulse generator when the last pulse waveform in the cycle is included is a drive pulse train including the third and fifth pulse waveforms in one cycle, and is one of the unit regions. When the drive pulse train generated for the previous unit region does not include the last pulse waveform in one cycle of the ejection drive signal, the drive pulse train generated by the drive pulse generating means is the second and fourth drive pulse trains in one cycle. A drive pulse train including a second pulse waveform, and when the grayscale data for the unit region is data for minimal dots, the drive pulse train generated for the unit region immediately before the unit region is The drive pulse train generated by the drive pulse generator when the last pulse waveform in one cycle of the ejection drive signal is included is a drive pulse train including the fourth pulse waveform in one cycle. The drive pulse train generated by the drive pulse generator when the drive pulse train generated for the previous unit region does not include the last pulse waveform in one cycle of the ejection drive signal is the third pulse pulse in the cycle. It is a drive pulse train including the pulse waveform of.

  The concept of the present invention can also be applied to a mode using a so-called multi-common waveform. That is, the present invention includes a head member having a nozzle opening, pressure changing means for changing the pressure of the liquid in the nozzle opening portion to discharge a liquid droplet, and the nozzle opening of the head member facing and substantially from the nozzle opening. An ejected medium holding unit that holds the liquid ejected medium so as to be separated by a distance; a moving mechanism that moves the head member relative to the liquid ejected medium; and a plurality of different pulse waveforms and the same cycle. Drive signal generating means for generating a plurality of ejection drive signals that are periodic signals, gradation data for the unit area for each unit area of the liquid ejection medium, the plurality of ejection drive signals, and the unit area Based on information on whether or not the drive pulse train generated for the previous unit area includes the last pulse waveform in one cycle of the plurality of ejection drive signals. Drive pulse generation means for generating a drive pulse train, and a control main body for driving pressure fluctuation means based on the drive pulse, wherein one period of the plurality of ejection drive signals is a unit of the liquid ejection medium The liquid ejecting apparatus corresponds to a region.

  According to the present invention, information on whether or not the drive pulse train generated for the previous unit region (for example, pixel) includes the last pulse waveform in one cycle of the plurality of ejection drive signals. Since the drive pulse train is generated based on this, it is possible to realize the generation of the drive pulse train in consideration of the residual vibration of the liquid meniscus of the nozzle opening that ejects the liquid droplet by the last pulse waveform.

  For example, the gradation data includes small dot data for forming small dots on the liquid ejection medium, and when the gradation data for the unit area is the small dot data, the unit The drive pulse train generated by the drive pulse generator when the drive pulse train generated for the unit region immediately before the region includes the last pulse waveform in one cycle of the plurality of ejection drive signals. At least the first pulse waveform is driven when the drive pulse train generated for the unit area immediately before the unit area does not include the last pulse waveform in one cycle of the plurality of ejection drive signals. It is preferable to have a backward shifted relationship with respect to at least the first pulse waveform of the drive pulse train generated by the pulse generation means.

  In addition, the present invention provides a head member having a nozzle opening, pressure changing means for changing the pressure of the liquid in the nozzle opening portion to discharge a liquid drop, and facing the nozzle opening of the head member and is substantially equal to the nozzle opening. Control for controlling a liquid ejecting apparatus comprising: an ejected medium holding unit that retains the liquid ejected medium so as to be separated by a distance; and a moving mechanism that moves the head member relative to the liquid ejected medium. An apparatus for generating a discharge drive signal that is a periodic signal having a plurality of pulse waveforms; for each unit region of the liquid ejection medium, gradation data for the unit region; Based on the drive signal and information on whether or not the drive pulse train generated for the unit area immediately before the unit area includes the last pulse waveform in one cycle of the ejection drive signal. Drive pulse generation means for generating a drive pulse train, and a control main body for driving the pressure fluctuation means based on the drive pulse, and one period of the ejection drive signal corresponds to one unit region of the liquid ejection medium It is the control apparatus characterized by having carried out.

  Alternatively, the present invention provides a head member having a nozzle opening, pressure changing means for changing the pressure of the liquid in the nozzle opening portion to discharge liquid droplets, and the nozzle opening of the head member facing the nozzle opening and substantially equal to the nozzle opening. Control for controlling a liquid ejecting apparatus comprising: an ejected medium holding unit that retains the liquid ejected medium so as to be separated by a distance; and a moving mechanism that moves the head member relative to the liquid ejected medium. An apparatus for generating a plurality of ejection drive signals, which are periodic signals having a plurality of different pulse waveforms and the same period, and a unit area for each unit area of the liquid ejection medium The drive pulse train generated for the gradation data, the plurality of ejection drive signals, and the unit region immediately before the unit region is within one cycle of the plurality of ejection drive signals. Drive pulse generation means for generating a drive pulse train based on whether or not a subsequent pulse waveform is included, and a control main body for driving the pressure fluctuation means based on the drive pulse, the plurality One period of the ejection drive signal corresponds to one unit region of the liquid ejection medium.

  Each control device or each component of the control device may be realized by a computer system.

  Further, a program for causing the computer system to realize each control device or each component of the control device and a computer-readable recording medium storing the program are also subject to protection in this case.

  Here, the recording medium includes not only a floppy disk or the like that can be recognized as a single unit, but also a network that propagates various signals.

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

  FIG. 1 is a schematic perspective view of an ink jet printer 1 which is a liquid ejecting apparatus according to a first embodiment of the present invention. In the inkjet printer 1, a carriage 2 is movably attached to a guide member 3. The carriage 2 is connected to a timing belt 6 that is stretched between a drive pulley 4 and an idle pulley 5. The drive pulley 4 is joined to the rotating shaft of the pulse motor 7. With the above configuration, the carriage 2 is moved (main scanning) in the width direction of the recording paper 8 by driving the pulse motor 7.

  A recording head 10 (head member) is attached to the surface (lower surface) of the carriage 2 facing the recording paper 8.

  As shown in FIG. 2, the recording head 10 includes a comb-like piezoelectric vibrator 15 inserted into a storage chamber 72 of a box-like case 71 made of plastic, for example, through one opening, and a comb-like tip portion. 15a faces the other opening. The flow path unit 74 is joined to the surface (lower surface) of the case 71 on the other opening side, and the comb-shaped tip portions 15 a are in contact with and fixed to predetermined portions of the flow path unit 74.

  The piezoelectric vibrator 15 is configured by cutting a plate-like vibrator plate in which common internal electrodes 15c and individual internal electrodes 15d are alternately stacked with a piezoelectric body 15b interposed therebetween, and cutting them into comb-like shapes corresponding to the dot formation density. It is. Then, by applying a potential difference between the common internal electrode 15c and the individual internal electrode 15d, each piezoelectric vibrator 15 expands and contracts in the vibrator longitudinal direction orthogonal to the stacking direction.

  The channel unit 74 is configured by laminating the nozzle plate 14 and the elastic plate 77 on both sides with the channel forming plate 75 interposed therebetween.

  The flow path forming plate 75 communicates with a plurality of nozzle openings 13 provided in the nozzle plate 14 and is arranged at least at one end of each pressure generating chamber 16 and a plurality of pressure generating chambers 16 arranged with a pressure generating chamber partition therebetween. This is a plate material on which a plurality of ink supply portions 82 communicating with each other and an elongated common ink chamber 83 communicating with all the ink supply portions 82 are formed. For example, an elongated common ink chamber 83 is formed by etching a silicon wafer, and pressure generating chambers 16 are formed along the longitudinal direction of the common ink chamber 83 in accordance with the pitch of the nozzle openings 13. A groove-shaped ink supply part 82 may be formed between the ink 16 and the common ink chamber 83. In this case, the ink supply unit 82 is connected to one end of the pressure generating chamber 16, and the nozzle opening 13 is disposed in the vicinity of the end opposite to the ink supply unit 82. The common ink chamber 83 is a chamber for supplying the ink stored in the ink cartridge to the pressure generating chamber 16, and an ink supply pipe 84 is communicated with substantially the center in the longitudinal direction.

  The elastic plate 77 is laminated on the surface of the flow path forming plate 75 opposite to the nozzle plate 14, and a double structure in which a polymer film such as PPS is laminated on the lower surface side of the stainless steel plate 87 as an elastic film 88. It is. An island portion 89 for abutting and fixing the piezoelectric vibrator 15 is formed by etching a portion of the stainless plate 87 corresponding to the pressure generating chamber 16.

  In the recording head 10 having the above configuration, by extending the piezoelectric vibrator 15 in the longitudinal direction of the vibrator, the island portion 89 is pressed toward the nozzle plate 14 and the elastic film 88 around the island portion 89 is deformed. The pressure generation chamber 16 contracts. When the piezoelectric vibrator 15 is contracted in the longitudinal direction from the contracted state of the pressure generating chamber 16, the pressure generating chamber 16 expands due to the elasticity of the elastic film 88. When the pressure generation chamber 16 is once expanded and then contracted, the ink pressure in the pressure generation chamber 16 is increased and ink droplets are ejected from the nozzle openings 13.

  That is, in the recording head 10, the capacity of the corresponding pressure chamber 16 changes as the piezoelectric vibrator 15 is charged / discharged. By utilizing such pressure fluctuations in the pressure chamber 16, ink droplets can be ejected from the nozzle openings 13, or the meniscus (the free surface of the ink exposed at the nozzle openings 13) can be finely vibrated.

  In place of the longitudinal vibration vibration mode piezoelectric vibrator 15, a so-called flexural vibration mode piezoelectric vibrator may be used. The piezoelectric vibrator in the flexural vibration mode is a piezoelectric vibrator that contracts the pressure chamber by deformation due to charging and expands the pressure chamber by deformation due to discharge. When a flexural vibration mode piezoelectric vibrator is used, the relationship between the rise and fall of a waveform signal, which will be described later, is reversed as compared with the case where a longitudinal vibration mode piezoelectric vibrator 15 is used (the polarity is reversed). Become).

  The recording head 10 is preferably a multicolor recording head capable of recording a plurality of different types of colors. The multicolor recording head includes a plurality of head units, and the type of ink used for each head unit is set.

  For example, a recording head having six head units includes a black head unit capable of ejecting black ink, a cyan head unit capable of ejecting cyan ink, a light cyan head unit capable of ejecting light cyan ink, and magenta ink. A magenta head unit capable of ejecting light, a light magenta head unit capable of ejecting light magenta ink, and a yellow head unit capable of ejecting yellow ink.

  The printer 1 configured as described above ejects ink from the recording head 10 as ink droplets in synchronization with the main scanning of the carriage 2 during the recording operation. On the other hand, the platen is rotated in conjunction with the reciprocating movement of the carriage 2 to move the recording paper 8 in the paper feed direction (ie, sub-scanning). As a result, images, characters and the like based on the recording data are recorded on the recording paper 8.

  Next, the electrical configuration of the ink jet printer will be described. As shown in FIG. 3, the printer 1 includes a printer controller 23 and a print engine 24.

  The printer controller 23 includes an external interface (external I / F) 25, a RAM 26 that temporarily stores various data, a ROM 27 that stores a control program, a control unit 28 that includes a CPU, a clock, and the like. Based on the oscillation circuit 29 that generates the signal (CK), the discharge drive signal generation circuit 30 that generates the discharge drive signal (COM) to be supplied to the recording head 10, and the drive signal and print data (discharge data). And an internal interface (internal I / F) 31 that transmits the developed dot pattern data (bitmap data) and the like to the print engine 24.

  The external I / F 25 receives print data including, for example, a character code, a graphic function, image data, and the like from a host computer (not shown). Also, a busy signal (BUSY) and an acknowledge signal (ACK) are output to the host computer or the like through the external I / F 25.

  The RAM 26 includes a reception buffer, an intermediate buffer, an output buffer, and a work memory (not shown). The reception buffer temporarily stores print data received via the external I / F 25, the intermediate buffer stores intermediate code data converted by the control unit 28, and the output buffer stores dot pattern data. Remember. Here, the dot pattern data is print data obtained by decoding (translating) the intermediate code data.

  The ROM 27 stores font data, graphic functions, and the like in addition to a control program (control routine) for performing various data processing.

  The control unit 28 performs various controls according to the control program stored in the ROM 27. For example, the print data in the reception buffer is read and the print data is converted into intermediate code data, and the intermediate code data is stored in the intermediate buffer. In addition, the control unit 28 analyzes the intermediate code data read from the intermediate buffer and develops (decodes) it into dot pattern data with reference to the font data and graphic functions stored in the ROM 27. Then, the control unit 28 stores the dot pattern data in the output buffer after performing necessary decoration processing. Each dot pattern data is composed of 3-bit data in this case as gradation data (print data).

  If dot pattern data for one line that can be recorded by one main scan of the recording head 10 is obtained, the dot pattern data for one line is sequentially transferred from the output buffer to the recording head 10 through the internal I / F 31. Is output. When dot pattern data for one line is output from the output buffer, the developed intermediate code data is erased from the intermediate buffer, and the development process for the next intermediate code data is performed.

  Further, the control unit 28 constitutes a part of the timing signal generating means, and supplies a latch signal (LAT) and channel signals (CH1, CH2) to the recording head 10 through the internal I / F 31. These latch signals and channel signals define the supply start timing of each waveform element of the pulse signal constituting the ejection drive signal (COM).

  On the other hand, the print engine 24 includes a paper feed motor 35 as a paper feed mechanism, a pulse motor 7 as a carriage feed mechanism, and an electric drive system 33 of the recording head 10. The paper feed motor 35 rotates the platen 34 (see FIG. 1) to move the recording paper 8, and the pulse motor 7 causes the carriage 2 to travel via the timing belt 6.

  As shown in FIG. 3, the electric drive system 33 of the recording head 10 includes a shift register circuit including a first shift register 36, a second shift register 37, and a third shift register 38, a first latch circuit 39, and a second latch. A latch circuit including a circuit 40 and a third latch circuit 41, a decoder 42, a control logic 43, a level shifter 44, a switch circuit 46, and the piezoelectric vibrator 15 are provided.

  Each of these shift registers, latch circuits, decoders, switch circuits, and piezoelectric vibrators are provided as first shift registers 36A to 36N provided for each nozzle opening 13 of the recording head 10, as shown in FIG. 2 shift registers 37A-37N, third shift registers 38A-38N, first latch circuits 39A-39N, second latch circuits 40A-40N, third latch circuits 41A-41N, recorders 42A-42N, switch circuits 46A-46N, and The piezoelectric vibrators 15A to 15N are configured.

  With such an electric drive system 33, the recording head 10 ejects ink droplets based on the gradation data from the printer controller 23. The grayscale data (SI) from the print controller 23 is synchronized with the clock signal (CK) from the oscillation circuit 29, and from the internal I / F 31 to the first shift register 36, the second shift register 37, and the third shift register 38. Serially transmitted.

  Here, the gradation data from the printer controller 23 is 3-bit data as described above. Specifically, in the case of the present embodiment, non-recording is (000) and minimal dots are (001) for six gradations composed of non-recording, minimal dots, small dots, medium dots, large dots, and maximal dots. ), The small dot is (011), the medium dot is (101), the large dot is (110), and the maximum dot is (111).

  Such gradation data is set for each dot, that is, for each nozzle opening 13. Then, the lower bit data of the gradation data for all the nozzle openings 13 is input to the first shift register 36 (36A to 36N), and the middle bit data of the 3-bit data for all the nozzle openings 13 is the first bit data. 2 is input to the shift register 37 (37A to 37N), and the upper bit data of the 3-bit data is input to the third shift register 38 (38A to 38N) for all the nozzle openings 13.

  As shown in FIGS. 3 and 4, a first latch circuit 39 is electrically connected to the first shift register 36. Similarly, a second latch circuit 40 is electrically connected to the second shift register 37. Similarly, a third latch circuit 41 is electrically connected to the third shift register 38. When a latch signal (LAT) from the print controller 23 is input to each of the latch circuits 39 to 41, the first latch circuit 39 latches the lower bit data of the 3-bit data, and the second latch circuit 40 Latches the middle bit of the 3-bit data, and the third latch circuit 41 latches the upper bit of the 3-bit data.

  Thus, from the circuit unit composed of the first shift register 36 and the first latch circuit 39, the circuit unit composed of the second shift register 37 and the second latch circuit 40, the third shift register 38 and the third latch circuit 41. Each circuit unit functions as a memory circuit. That is, these circuit units temporarily store the gradation data before being input to the decoder 42 every 3 bits.

  The bit data latched by the latch circuits 39, 40, 41 is input to the decoders 42A to 42N. The decoder 42 translates 3-bit data (gradation data) to generate pulse selection data (pulse selection information). In this embodiment, the pulse selection data is composed of 5 bits, and each bit corresponds to each waveform element constituting the drive signal (COM). The supply / non-supply of the waveform element to the piezoelectric vibrator 15 is selected according to the contents of each bit (for example, (0), (1)). The details of the drive signal (COM) and the supply of the waveform elements will be described later.

  On the other hand, a timing signal from the control logic 43 is also input to the decoder 42. The control logic 43 functions as a timing signal generation unit together with the control unit 28, and generates a timing signal based on the latch signal (LAT) and the channel signals (CH1, CH2, CH3, CH4, CH5).

  The pulse selection data translated by the decoder 42 is input to the level shifter 44 every time the timing defined by the timing signal comes in order from the higher bit side. For example, the most significant bit data of the pulse selection data is input to the level shifter 44 at the first timing in the recording cycle, and the second bit data of the pulse selection data is input to the level shifter 44 at the second timing.

  The level shifter 44 functions as a voltage amplifier. When the pulse selection data is “1”, the level shifter 44 outputs an electric signal boosted to a voltage capable of driving the switch circuit 46, for example, a voltage of about several tens of volts.

  The pulse selection data “1” boosted by the level shifter 44 is supplied to a switch circuit 46 that functions as drive pulse generation means. The switch circuit 46 generates a drive pulse by selecting a waveform element included in the ejection drive signal (COM) based on the pulse selection data generated by translating the print data, and outputs the drive pulse to the piezoelectric vibrator 15. To supply. Therefore, the drive signal (COM) from the ejection drive signal generation circuit 30 is supplied to the input side of the switch circuit 46, and the piezoelectric vibrator 15 is connected to the output side thereof.

  The pulse selection data controls the operation of the switch circuit 46. For example, during the period when the pulse selection data applied to the switch circuit 46 is “1”, the switch circuit 46 is in a connected state, and the drive pulse of the ejection drive signal COM is supplied to the piezoelectric vibrator 15. As a result, the potential level of the piezoelectric vibrator 15 changes.

  On the other hand, while the pulse selection data applied to the switch circuit 46 is “0”, the level shifter 44 does not output an electrical signal for operating the switch circuit 46. For this reason, the switch circuit 46 is disconnected and the drive pulse of the drive signal is not supplied to the piezoelectric vibrator 15.

  Next, an ejection drive signal (COM) generated by the ejection drive signal generation circuit 30 and ink droplet ejection control based on the drive signal will be described in detail.

  The ejection drive signal COM shown in FIG. 5 includes a first pulse waveform signal PS1 arranged in the period T1, a second pulse waveform signal PS2 arranged in the period T2, and a third pulse waveform signal PS3 arranged in the period T3. And a fourth pulse waveform signal PS4 arranged in the period T4 and a fifth pulse waveform signal PS5 arranged in the period T5 are connected in series, and are pulse train waveform signals repeatedly generated at the recording period TA. . In the present embodiment, the periods T1, T2, T3, T4, and T5 are set as the same time.

  The first pulse waveform signal PS1 to the fifth pulse waveform signal PS5 have the same waveform shape, and are signals for ejecting about 6 ng of ink droplets independently.

  Specifically, each of the pulse waveform signals PS1, PS2, PS3, PS4, and PS5 has a first charging element P1 that increases the potential from the intermediate potential VM to the maximum potential VH along the gradient θ1, and the maximum potential VH is short. A first hold element P2 that maintains time, a first discharge element P3 that drops the potential from the highest potential VH to the lowest potential VL along the steep slope θ2, and a second hold element P4 that maintains the lowest potential. And a second charging element P5 that increases the potential from the lowest potential VL to the intermediate potential VM along the gradient θ3.

  When the first charging element P1 is supplied and the piezoelectric vibrator 15 is charged from the intermediate potential VM, the volume of the pressure generating chamber 16 expands from the reference volume to the maximum volume. And the pressure generating chamber 16 contracts rapidly to the minimum volume by the first discharge element P3. The contracted state of the pressure generating chamber 16 is maintained over a period during which the second hold element P4 is supplied. By abruptly contracting the pressure generating chamber 16 and maintaining the contracted state, the ink pressure in the pressure generating chamber 16 is rapidly increased, and ink droplets are ejected from the nozzle openings 13. The amount of ink droplets ejected at this time is about 6 ng. Then, the pressure generating chamber 16 is expanded and restored by the second charging element P5 in order to converge the meniscus vibration in a short time.

  As shown in FIG. 6, gradation control can be performed by appropriately selecting a pulse waveform signal to be supplied to the piezoelectric vibrator 15. That is, non-recording is realized by not supplying any waveform signal as a drive pulse, and recording of a minimum dot is performed by supplying the third pulse waveform signal PS3 as a drive pulse, and the second pulse waveform signal PS2 and the fourth pulse are recorded. Small dots are recorded by supplying the pulse waveform signal PS4 as a drive pulse, and medium dots are recorded by supplying the second pulse waveform signal PS2, the third pulse waveform signal PS3, and the fourth pulse waveform signal PS4 as drive pulses. Recording is performed, large dots are recorded by supplying the second pulse waveform signal PS2 to the fifth pulse waveform signal PS5 as drive pulses, and the first pulse waveform signal PS1 to the fifth pulse waveform signal PS5 are supplied as drive pulses. By doing so, it is possible to record maximum dots. At this time, the five pulse waveform signals PS1, PS2, PS3, PS4, and PS5 appear at equal intervals.

  The gradation control is gradation control for the first pixel (unit region) in each row. For the second and subsequent pixels in each row, as a feature of the present invention, the drive pulse train generated for the previous pixel is the fifth pulse waveform signal PS5 (the last pulse waveform in one cycle of the ejection drive signal COM). The mode of gradation control changes depending on whether it is included or not.

  When the drive pulse train generated for the immediately preceding pixel does not include the fifth pulse waveform signal PS5, the same gradation control as that described above is performed.

  When the drive pulse train generated for the immediately preceding pixel includes the fifth pulse waveform signal PS5, the gradation control mode changes only for the recording of the very small dots and the recording of the small dots. Specifically, by recording the fourth pulse waveform signal PS4 as a drive pulse, recording of a minimum dot is performed (minimum dot (2)), and the third pulse waveform signal PS3 and the fifth pulse waveform signal PS5 are used as a drive pulse. Gradation control is performed in which small dots are recorded (small dots (2)). That is, these drive pulse trains (including at least the first pulse waveform of the drive pulse train) have a relationship shifted backward in time with respect to the case of the gradation control.

  Here, non-ejection (non-recording) dot pattern data (gradation information (000)), dot pattern data of extremely small dots (gradation information (001)), dot pattern data of small dots (gradation information (011)) ), Dot pattern data for medium dots (gradation information (101)), dot pattern data for large dots (gradation information (110)), and dot pattern data for maximum dots (gradation information (111)). The pulse selection data to be performed will be specifically described.

  The decoder 42 generates 5-bit pulse selection data according to 3-bit data of each dot pattern data. Specifically, when the drive pulse train generated for the immediately preceding pixel does not include the fifth pulse waveform signal PS5, when the dot pattern data is (000), pulse selection data (00000) is generated, When the dot pattern data is (001), pulse selection data (00100) is generated. When the dot pattern data is (011), pulse selection data (01010) is generated. When the dot pattern data is (101), When the pulse selection data (01110) is generated and the dot pattern data is (110), the pulse selection data (01111) is generated. When the dot pattern data is (111), the pulse selection data (11111) is generated. .

  When the drive pulse train generated for the immediately preceding pixel includes the fifth pulse waveform signal PS5, when the dot pattern data is (000), pulse selection data (00000) is generated and the dot pattern data is In the case of (001), pulse selection data (00010) is generated, in the case of dot pattern data (011), pulse selection data (00101) is generated, and in the case of dot pattern data (101), pulse selection data ( When the dot pattern data is (110), pulse selection data (01111) is generated. When the dot pattern data is (111), pulse selection data (11111) is generated.

  The most significant bit of the 5-bit pulse selection data corresponds to the first pulse waveform signal PS1, the second bit corresponds to the second pulse waveform signal PS2, and the third bit corresponds to the third pulse waveform signal PS3. The fourth bit corresponds to the fourth pulse waveform signal PS4, and the fifth bit corresponds to the fifth pulse waveform signal PS5.

  When the most significant bit of the pulse selection data is “1”, from the first timing signal (latch signal) corresponding to the beginning of the period T1 to the second timing signal (CH signal) corresponding to the beginning of the period T2. During this period, the switch circuit 46 (driving pulse supply means) is connected. When the second bit is “1”, the switch circuit 46 is in the connected state from the second timing signal to the third timing signal (CH signal) corresponding to the beginning of the period T3. Similarly, when the third bit is “1”, the switch circuit 46 is in a connected state from the third timing signal to the fourth timing signal (latch signal) corresponding to the start end of the period T4. When the fourth bit is “1”, the switch circuit 46 is in a connected state from the fourth timing signal to the fifth timing signal (CH signal) corresponding to the beginning of the period T5. When the fifth bit is “1”, the switch circuit 46 is in a connected state from the fifth timing signal to the timing signal (latch signal) corresponding to the beginning of the period T1 in the next printing cycle TA.

  Thereby, the pulse waveform signal is not supplied to the corresponding piezoelectric vibrator 15 based on the non-recorded dot pattern data. Further, the second pulse waveform signal PS2, the third pulse waveform signal PS3, and the fourth pulse waveform signal PS4 are supplied based on the dot pattern data of medium dots. The second pulse waveform signal PS2, the third pulse waveform signal PS3, the fourth pulse waveform signal PS4, and the fifth pulse waveform signal PS5 are supplied based on the dot pattern data of large dots. The first pulse waveform signal PS1, the second pulse waveform signal PS2, the third pulse waveform signal PS3, the fourth pulse waveform signal PS4, and the fifth pulse waveform signal PS5 are supplied based on the dot pattern data of the maximum dots. .

  As a result, corresponding to the dot pattern data of medium dots, approximately 6 ng of ink droplets are ejected from the nozzle opening 13 three times, and medium dots are formed on the recording paper 8. Corresponding to the dot pattern data for large dots, approximately 6 ng of ink droplets are ejected four times from the nozzle openings 13 to form large dots on the recording paper 8. Corresponding to the dot pattern data of maximal dots, approximately 6 ng of ink droplets are ejected from the nozzle opening 13 five times, and large dots are formed on the recording paper 8.

  Furthermore, in the case where the drive pulse train generated for the immediately preceding pixel does not include the fifth pulse waveform signal PS5, the third pulse waveform is applied to the corresponding piezoelectric vibrator 15 based on the dot pattern data of the minimum dots. The signal PS3 is supplied, and the second pulse waveform signal PS2 and the fourth pulse waveform signal PS4 are supplied to the corresponding piezoelectric vibrator 15 based on the dot pattern data of the small dots.

  Alternatively, when the drive pulse train generated for the immediately preceding pixel includes the fifth pulse waveform signal PS5, the corresponding piezoelectric vibrator 15 has the fourth pulse waveform based on the dot pattern data of the minimum dots. The signal PS4 is supplied, and the third pulse waveform signal PS3 and the fifth pulse waveform signal PS5 are supplied to the corresponding piezoelectric vibrator 15 based on the dot pattern data of the small dots.

  As a result, an ink droplet of about 6 ng is ejected once from the nozzle opening 13 corresponding to the dot pattern data of the minimal dot, and a minimal dot is formed on the recording paper 8. Corresponding to the dot pattern data of small dots, approximately 6 ng of ink droplets are ejected twice from the nozzle openings 13 to form small dots on the recording paper 8.

  In the present embodiment, when the drive pulse train for the previous pixel includes the fifth pulse waveform signal PS5, the ink droplets ejected for the current pixel are affected by the residual vibration of the liquid meniscus. There is a tendency that the speed is increased (this increases the landing speed). In such a case, as described above, the driving pulse train for the current pixel is selected so as to shift backward in time (thus delaying landing), thereby canceling the tendency. It has become. Specifically, the drive pulse selection mode is made different between the dot pattern data of extremely small dots and the dot pattern data of small dots. Accordingly, it is possible to generate a drive pulse train in consideration of the residual vibration of the ink meniscus in the nozzle opening 13 that ejects ink droplets by the fifth pulse waveform signal PS5.

  The ejection drive signal generation circuit 30 may be formed by a DAC circuit or an analog circuit.

  In the above description, the decoding mode of the decoder 42 changes depending on whether or not the drive pulse train for the previous pixel includes the fifth pulse waveform signal PS5. The gradation data is changed depending on whether or not the drive pulse train for the previous pixel includes the fifth pulse waveform signal PS5 (for example, the drive pulse train for the previous pixel has the fifth pulse waveform). In the case of including the signal PS5, (001) → (010), (011) → (100)), it is also possible to fix the decoding mode itself corresponding to each gradation data.

  Next, a second embodiment of the present invention will be described. In the present embodiment, as shown in FIG. 7, instead of the drive signal generation circuit 30, a first discharge drive signal generation circuit 30a that generates a first discharge drive signal (COM1) to be supplied to the recording head 10; And a second ejection drive signal generation circuit 30b that generates a second ejection drive signal (COM2) to be supplied to the recording head 10.

  The decoder 42 'translates 3-bit data (gradation data) to generate first pulse selection data and second pulse selection data (pulse selection information). In the present embodiment, the first pulse selection data and the second pulse selection data are each composed of 3 bits, and each bit corresponds to each waveform element constituting each drive signal (COM1, COM2). The supply / non-supply of the waveform element to the piezoelectric vibrator 15 is selected according to the contents of each bit (for example, (0), (1)).

  The first pulse selection data translated by the decoder 42 'is input to the first level shifter 44' every time the timing defined by the timing signal comes in order from the higher bit side. For example, the most significant bit data of the first pulse selection data is input to the first level shifter 44 ′ at the first timing in the recording cycle, and the second bit data in the first pulse selection data is the first at the second timing. Input to level shifter 44 '.

  Similarly, the second pulse selection data translated by the decoder 42 'is input to the second level shifter 45' every time the timing defined by the timing signal comes in order from the higher bit side. For example, the most significant bit data of the second pulse selection data is input to the second level shifter 45 ′ at the first timing in the recording cycle, and the second bit data in the second pulse selection data is the second at the second timing. Input to level shifter 45 '.

  The first level shifter 44 ′ and the second level shifter 45 ′ function as voltage amplifiers. When the pulse selection data is “1”, voltages that can drive the first switch circuit 46 ′ and the second switch circuit 47 ′, for example, An electric signal boosted to a voltage of about several tens of volts is output.

  The pulse selection data “1” boosted by the first level shifter 44 ′ is supplied to the first switch circuit 46 ′ that functions as drive pulse generation means. The first switch circuit 46 ′ generates a drive pulse by selecting a waveform element included in the first ejection drive signal (COM1) based on the first pulse selection data generated by translating the print data. A drive pulse is supplied to the piezoelectric vibrator 15. Accordingly, the drive signal (COM1) from the first ejection drive signal generation circuit 30a is supplied to the input side of the first switch circuit 46 ′, and the piezoelectric vibrator 15 is connected to the output side thereof. Has been.

  The first pulse selection data controls the operation of the first switch circuit 46 '. For example, during the period when the pulse selection data applied to the first switch circuit 46 ′ is “1”, the first switch circuit 46 ′ is in a connected state, and the drive pulse of the first ejection drive signal COM 1 is applied to the piezoelectric vibrator 15. Supplied. As a result, the potential level of the piezoelectric vibrator 15 changes.

  On the other hand, during the period when the pulse selection data applied to the first switch circuit 46 ′ is “0”, the electric signal for operating the first switch circuit 46 ′ is not output from the first level shifter 44 ′. For this reason, the first switch circuit 46 ′ is disconnected and the drive pulse of the drive signal is not supplied to the piezoelectric vibrator 15.

  On the other hand, the pulse selection data “1” boosted by the second level shifter 45 ′ is supplied to the second switch circuit 47 ′ functioning as drive pulse generation means. The second switch circuit 47 ′ selects a waveform element included in the second ejection drive signal (COM2) based on the second pulse selection data generated by the translation of the print data and generates a drive pulse. A drive pulse is supplied to the piezoelectric vibrator 15. Accordingly, the drive signal (COM2) from the second ejection drive signal generation circuit 30b is supplied to the input side of the second switch circuit 47 ′, and the piezoelectric vibrator 15 is connected to the output side thereof. Has been.

  The second pulse selection data controls the operation of the second switch circuit 47 '. For example, during a period in which the pulse selection data applied to the second switch circuit 47 ′ is “1”, the second switch circuit 47 ′ is in a connected state, and the drive pulse of the second ejection drive signal COM2 is applied to the piezoelectric vibrator 15. Supplied. As a result, the potential level of the piezoelectric vibrator 15 changes.

  On the other hand, during the period when the pulse selection data applied to the second switch circuit 47 'is "0", the electric signal for operating the second switch circuit 47' is not output from the second level shifter 45 '. For this reason, the second switch circuit 47 ′ is disconnected and the drive pulse of the drive signal is not supplied to the piezoelectric vibrator 15.

  Since the other configuration of the present embodiment is substantially the same as that of the first embodiment, description thereof is omitted.

  Next, the first ejection drive signal (COM1) generated by the first ejection drive signal generation circuit 30a, the second ejection drive signal (COM2) generated by the second ejection drive signal generation circuit 30b, and the drive signals Ink droplet ejection control will be described in detail.

  The first ejection drive signal COM1 shown in FIG. 8 includes a first pulse waveform signal PS11 arranged in the period T11, a second pulse waveform signal PS12 arranged in the period T12, and a third pulse waveform arranged in the period T13. The signal PS13 is connected in series and is a pulse train waveform signal repeatedly generated at the recording period TB. In the present embodiment, the periods T11, T12, and T13 are set as the same time.

  Each of the first pulse waveform signal PS11 and the second pulse waveform signal PS12 has the same waveform shape, and is a signal for ejecting a small amount of ink droplets.

  That is, each of these pulse waveform signals PS11 and PS12 includes a first charging element P11 that increases the potential from the intermediate potential VM to the maximum potential VH along the gradient θ11, and a first hold element that maintains the maximum potential VH1 for a short time. P12, a first discharge element P13 that drops the potential from the highest potential VH to the lowest potential VL along the steep slope θ12 in a very short time, a second hold element P14 that maintains the lowest potential, and a slope from the lowest potential VL1 The second charging element P15 is configured to increase the potential to the intermediate potential VM along θ13.

  When the pulse waveform signals PS11 and PS12 are supplied to the piezoelectric vibrator 15, approximately 3 pl of ink droplets are ejected from the nozzle openings 13.

  More specifically, when the first charging element P11 is supplied and the piezoelectric vibrator 15 is charged from the intermediate potential VM, the volume of the pressure generating chamber 16 expands from the reference volume to the maximum volume. And the pressure generation chamber 16 contracts rapidly to the minimum volume by the first discharge element P13. The contracted state of the pressure generating chamber 16 is maintained over a period during which the second hold element P14 is supplied. By abruptly contracting the pressure generating chamber 16 and maintaining the contracted state, the ink pressure in the pressure generating chamber 16 is rapidly increased, and ink droplets are ejected from the nozzle openings 13. The amount of ink droplets ejected at this time is about 3 pl. Then, the pressure generating chamber 16 is expanded and restored by the second charging element P15 in order to converge the meniscus vibration in a short time.

  On the other hand, the third pulse waveform signal PS13 is a signal for ejecting a medium amount of ink droplets.

  That is, the pulse waveform signal PS13 includes a first charging element P21 that increases the potential from the intermediate potential VM to the maximum potential VH2 (> VH1) along the gradient θ21, and a first hold element P22 that maintains the maximum potential VH2 for a short time. A first discharge element P23 that drops the potential from the highest potential VH2 to the lowest potential VL2 (<VH1) along the steep slope θ22 in a very short time, a second hold element P24 that maintains the lowest potential, and the lowest potential The second charging element P25 is configured to increase the potential from VL2 to the intermediate potential VM along the gradient θ23.

  When the first charging element P21 is supplied and the piezoelectric vibrator 15 is charged from the intermediate potential VM, the volume of the pressure generating chamber 16 expands from the reference volume to the maximum volume. And the pressure generation chamber 16 contracts rapidly to the minimum volume by the first discharge element P23. The contracted state of the pressure generating chamber 16 is maintained over a period during which the second hold element P24 is supplied. By abruptly contracting the pressure generating chamber 16 and maintaining the contracted state, the ink pressure in the pressure generating chamber 16 is rapidly increased, and ink droplets are ejected from the nozzle openings 13. The amount of ink droplets ejected at this time is about 7 pl. Then, the pressure generating chamber 16 is expanded and restored by the second charging element P25 so as to converge the meniscus vibration in a short time.

  On the other hand, the second ejection drive signal COM2 shown in FIG. 8 is arranged in the fourth pulse waveform signal PS14 arranged in the period T11, the fifth pulse waveform signal PS15 arranged in the period T12, and the period T13. The sixth pulse waveform signal PS16 is connected in series and is a pulse train waveform signal repeatedly generated at the recording cycle TB.

  Both the fourth pulse waveform signal PS14 and the fifth pulse waveform signal PS15 have the same waveform as the third pulse waveform signal PS13.

  The sixth pulse waveform signal PS16 has the same waveform as the first pulse waveform signal PS11 and the second pulse waveform signal PS12.

  Then, as shown in FIG. 9, gradation control can be performed by appropriately selecting a pulse waveform signal to be supplied to the piezoelectric vibrator 15. That is, recording a very small dot by supplying the second pulse waveform signal PS12 as a driving pulse, recording a small dot by supplying the fifth pulse waveform signal PS15 as a driving pulse, and the first pulse waveform signal PS11. By recording the second pulse waveform signal PS12 and the sixth pulse waveform signal PS16 as drive pulses, medium dots are recorded, and by supplying the fourth pulse waveform signal PS14 and the third pulse waveform signal PS13 as drive pulses. By recording a large dot and supplying the fourth pulse waveform signal PS14, the fifth pulse waveform signal PS15, and the third pulse waveform signal PS13 as drive pulses, the maximum dot can be recorded.

  Here, non-ejection (non-recording) dot pattern data (gradation information (000)), dot pattern data of extremely small dots (gradation information (001)), dot pattern data of small dots (gradation information (011)) ), Dot pattern data for medium dots (gradation information (101)), dot pattern data for large dots (gradation information (110)), and dot pattern data for maximum dots (gradation information (111)). The pulse selection data to be performed will be specifically described.

  In this case, the decoder 42 'generates the first pulse selection data and the second pulse selection data of 3 bits each according to the 3 bits of the dot pattern data. Specifically, when the dot pattern data is (000), the first pulse selection data (000) and the second pulse selection data (000) are generated, and when the dot pattern data is (011), the first pulse selection data (000) is generated. When the data (000) and the second pulse selection data (010) are generated and the dot pattern data is (101), the first pulse selection data (110) and the second pulse selection data (001) are generated, and the dot pattern When the data is (110), the first pulse selection data (001) and the second pulse selection data (100) are generated. When the dot pattern data is (111), the first pulse selection data (001) and the second pulse selection data (100) are generated. Pulse selection data (110) is generated.

  In the case where the dot pattern data is (001), whether the drive pulse train generated for the immediately preceding pixel includes the third pulse waveform signal PS13 or the sixth pulse waveform signal PS16 depends on the decoding mode. Is different. That is, when the drive pulse train generated for the immediately preceding pixel does not include the third pulse waveform signal PS13 or the sixth pulse waveform signal PS16, the first pulse selection data (010) and the second pulse selection data ( 000) and the drive pulse train generated for the previous pixel includes the third pulse waveform signal PS13 or the sixth pulse waveform signal PS16, the first pulse selection data (000) and the second pulse selection data (000) Pulse selection data (001) is generated.

  The most significant bit of the 3-bit first pulse selection data corresponds to the first pulse waveform signal PS11, the second bit corresponds to the second pulse waveform signal PS12, and the third bit corresponds to the third pulse waveform signal PS13. It corresponds.

  In addition, the most significant bit of the 3-bit second pulse selection data corresponds to the fourth pulse waveform signal PS14, the second bit corresponds to the fifth pulse waveform signal PS15, and the third bit corresponds to the sixth pulse waveform signal. It corresponds to PS16.

  When the most significant bit of the first pulse selection data is “1”, the second timing signal (CH signal) corresponding to the start end of the period T12 is changed from the first timing signal (latch signal) corresponding to the start end of the period T11. ) Until the first switch circuit 46 ′ (drive pulse supply means) is connected. When the second bit is “1”, the first switch circuit 46 ′ is in the connected state from the second timing signal to the third timing signal (CH signal) corresponding to the start end of the period T 13. Become. Similarly, when the third bit is “1”, the first switch circuit 46 ′ from the third timing signal to the timing signal (latch signal) corresponding to the start end of the period T11 in the next printing cycle TB. Is connected.

  On the other hand, when the most significant bit of the second pulse selection data is “1”, the second timing signal (CH signal) corresponding to the start end of the period T12 is changed from the first timing signal (latch signal) corresponding to the start end of the period T11. ) Until the second switch circuit 47 ′ (drive pulse supply means) is connected. When the second bit is “1”, the second switch circuit 47 ′ is in the connected state from the second timing signal to the third timing signal (CH signal) corresponding to the beginning of the period T13. Become. Similarly, when the third bit is “1”, the second switch circuit 47 ′ from the third timing signal to the timing signal (latch signal) corresponding to the start end of the period T11 in the next printing cycle TB. Is connected.

  Thereby, the pulse waveform signal is not supplied to the corresponding piezoelectric vibrator 15 based on the non-recorded dot pattern data. The fifth pulse waveform signal PS15 is supplied based on the dot pattern data of small dots. Further, the first pulse waveform signal PS11, the second pulse waveform signal PS12, and the sixth pulse waveform signal PS16 are supplied based on the dot pattern data of medium dots. The fourth pulse waveform signal PS14 and the third pulse waveform signal PS13 are supplied based on the dot pattern data of large dots. The fourth pulse waveform signal PS14, the fifth pulse waveform signal PS15, and the third pulse waveform signal PS13 are supplied based on the dot pattern data of the maximum dots.

  As a result, corresponding to the dot pattern data of small dots, about 7 pl of ink droplets are ejected once from the nozzle openings 13, and small dots are formed on the recording paper 8. Corresponding to the dot pattern data of medium dots, approximately 3 pl of ink droplets are ejected from the nozzle opening 13 three times, and medium dots are formed on the recording paper 8. Corresponding to the dot pattern data of large dots, approximately 7 pl of ink droplets are ejected twice from the nozzle openings 13 to form large dots on the recording paper 8. Corresponding to the dot pattern data of the maximal dots, approximately 7 pl of ink droplets are ejected three times from the nozzle openings 13 to form large dots on the recording paper 8.

  Further, when the drive pulse train generated for the immediately preceding pixel does not include the third pulse waveform signal PS13 or the sixth pulse waveform PS16, the corresponding piezoelectric vibrator 15 is applied to the corresponding piezoelectric vibrator 15 based on the dot pattern data of the extremely small dots. The second pulse waveform signal PS12 is supplied.

  Alternatively, when the drive pulse train generated for the immediately preceding pixel includes the third pulse waveform signal PS13 or the sixth pulse waveform PS16, the corresponding piezoelectric vibrator 15 is applied to the corresponding piezoelectric vibrator 15 based on the dot pattern data of the minimum dots. The sixth pulse waveform signal PS16 is supplied.

  As a result, an ink droplet of about 3 pl is ejected once from the nozzle opening 13 corresponding to the dot pattern data of the minimal dot, and a minimal dot is formed on the recording paper 8.

  In the present embodiment, when the drive pulse train for the previous pixel includes the third pulse waveform signal PS13 or the sixth pulse waveform signal PS16, the current pixel is affected by the residual vibration of the ink meniscus. There is a tendency that the speed of the ink droplets discharged to the ink increases. Therefore, in such a case, as described above, the drive pulse train for the current pixel (including at least the first pulse waveform of the drive pulse train) is selected so as to shift backward in time. Trends are offset. Specifically, the drive pulse selection mode is different for the dot pattern data of the minimal dots. Accordingly, it is possible to generate a drive pulse train in consideration of the residual vibration of the ink meniscus of the nozzle opening 13 that ejects ink droplets by the third pulse waveform signal PS13 or the sixth pulse waveform signal PS16.

  Note that the first ejection drive signal COM1 and the second ejection drive signal COM2 in the example of FIG. 8 are periodic signals each having three pulse waveforms in one cycle, but are periodic signals having a larger number of pulse waveforms. Of course there may be.

  The first ejection drive signal generation circuit 30a and the second ejection drive signal generation circuit 30b may be formed by a DAC circuit or an analog circuit.

  In the above description, the decoding mode of the decoder 42 ′ changes depending on whether the drive pulse train for the previous pixel includes the third pulse waveform signal PS13 or the sixth pulse waveform signal PS16. However, the gradation data is changed depending on whether the drive pulse train for the previous pixel includes the third pulse waveform signal PS13 or the sixth pulse waveform signal PS16 (for example, When the drive pulse train for the previous pixel includes the third pulse waveform signal PS13 or the sixth pulse waveform signal PS16 (as (001) → (010)), decoding corresponding to each gradation data is performed. It is possible that the embodiment itself is fixed.

  Further, in each of the above embodiments, the pressure fluctuation means is constituted by the piezoelectric vibrator 15, but the pressure fluctuation means for changing the pressure in the pressure chamber 16 is not limited to the piezoelectric vibrator 15. For example, a magnetostrictive element may be used as a pressure generating element, and the pressure chamber 16 may be expanded and contracted by the magnetostrictive element to cause pressure fluctuations, or a heating element may be used as the pressure generating element. You may comprise so that a pressure fluctuation may be produced in the pressure chamber 16 with the bubble which expands / contracts with heat.

  Further, as described above, the printer controller 23 is configured by a computer system. However, a program for causing the computer system to realize each element and a computer-readable recording medium 201 on which the program is recorded are also protected in this case. It is a target.

  Further, when each of the above elements is realized by a program such as an OS that operates on a computer system, a program including various instructions for controlling the program such as the OS and a recording medium 202 that records the program are also included in the present invention. It is a protection target.

  Here, the recording media 201 and 202 include not only a floppy disk (flexible disk) that can be recognized as a single unit but also a network that propagates various signals.

  Although the above description has been made with respect to an ink jet recording apparatus, the present invention broadly covers liquid ejecting apparatuses in general. As an example of the liquid, in addition to ink, glue, nail polish, liquid electrode material, bioorganic liquid, and the like can be used. Furthermore, the present invention can also be applied to an apparatus for manufacturing a color filter in a display body such as a liquid crystal.

1 is a schematic perspective view of an ink jet printer according to an embodiment of the present invention. 2 is a cross-sectional view illustrating an internal structure of a recording head. FIG. 2 is a block diagram illustrating an electrical configuration of a printer. FIG. 2 is a block diagram illustrating an electric drive system of a recording head. FIG. It is a figure which shows an example of a drive signal. It is a figure explaining the drive pulse which can be produced | generated based on the drive signal of FIG. It is a block diagram explaining the electric constitution of the printer in the 2nd Embodiment of this invention. It is a figure which shows an example of a multi-common drive signal. It is a figure explaining the drive pulse produced | generated based on the drive signal of FIG. It is a figure which shows the state of the residual vibration of an ink meniscus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inkjet printer 2 Carriage 3 Guide member 4 Drive pulley 5 Free pulley 6 Timing belt 7 Pulse motor 8 Recording paper 10 Recording head 11 Ink cartridge 12 Ink chamber 13 Nozzle opening 14 Nozzle plate 15 Piezoelectric vibrator 15a Comb-like tip 15b Piezoelectric body 15c Common internal electrode 15d Individual internal electrode 16 Pressure chamber 23 Printer controller 24 Print engine 25 External interface 26 RAM
27 ROM
28 Control Unit 29 Oscillation Circuit 30 Ejection Drive Signal Generation Circuit 30a First Ejection Drive Signal Generation Circuit 30b Second Ejection Drive Signal Generation Circuit 31 Internal Interface 33 Printhead Electric Drive System 34 Platen 35 Paper Feed Motor 36 First Shift Register 37 Second shift register 38 Third shift register 39 First latch circuit 40 Second latch circuit 41 Third latch circuit 42, 42 'Decoder 43 Control logic 44 Level shifter 44' First level shifter 45 'Second level shifter 46 Switch circuit 46' First 1 switch circuit 47 ′ second switch circuit 71 case 72 storage chamber 74 channel unit 75 channel forming plate 77 elastic plate 82 ink supply unit 83 common ink chamber 84 ink supply tube 87 stainless steel plate 88 elastic film 89 island unit

Claims (18)

A head member having a nozzle opening;
Pressure fluctuation means for changing the pressure of the liquid in the nozzle opening to discharge liquid droplets;
An ejected medium holding unit that holds the liquid ejected medium so as to face the nozzle openings of the head member and be separated from the nozzle openings by a substantially equal distance;
A moving mechanism for moving the head member relative to the liquid ejection medium;
Drive signal generating means for generating an ejection drive signal which is a periodic signal having a plurality of pulse waveforms;
For each unit area of the liquid ejection medium, the gradation data for the unit area, the ejection drive signal, and the drive pulse train generated for the unit area immediately before the unit area are represented by the ejection drive signal. Drive pulse generating means for generating a drive pulse train based on whether or not the last pulse waveform in one cycle is included; and
A control body for driving the pressure fluctuation means based on the drive pulse;
With
One period of the ejection drive signal corresponds to one unit region of the liquid ejection medium. The gradation data includes data for small dots for forming small dots on the liquid ejection medium,
When the gradation data for the unit area is small dot data,
When the drive pulse train generated for the unit region immediately before the unit region includes the last pulse waveform within one cycle of the ejection drive signal, at least the first drive pulse train generated by the drive pulse generator The pulse waveform is a drive pulse train generated by the drive pulse generator when the drive pulse train generated for the unit region immediately before the unit region does not include the last pulse waveform in one cycle of the ejection drive signal. 2. The liquid ejecting apparatus according to claim 1, wherein the liquid ejecting apparatus is in a relationship shifted backward in time with respect to at least a first pulse waveform of the first and second pulse waveforms. The liquid ejecting apparatus according to claim 1, wherein the ejection drive signal is a periodic signal having a plurality of pulse waveforms having the same shape within one period. The liquid ejecting apparatus according to claim 3, wherein the ejection driving signal is a periodic signal having five pulse waveforms having the same shape within one period. The gradation data includes data for small dots for forming small dots on the liquid ejection medium, and data for minimal dots for forming minimal dots on the liquid ejection medium,
When the gradation data for the unit area is small dot data,
When the drive pulse train generated for the unit region immediately before the unit region includes the last pulse waveform within one cycle of the ejection drive signal, at least the first drive pulse train generated by the drive pulse generator The pulse waveform is a drive pulse train generated by the drive pulse generator when the drive pulse train generated for the unit region immediately before the unit region does not include the last pulse waveform in one cycle of the ejection drive signal. In relation to at least the first pulse waveform of
When the gradation data for the unit area is data for minimal dots,
When the drive pulse train generated for the unit region immediately before the unit region includes the last pulse waveform within one cycle of the ejection drive signal, at least the first drive pulse train generated by the drive pulse generator The pulse waveform is a drive pulse train generated by the drive pulse generator when the drive pulse train generated for the unit region immediately before the unit region does not include the last pulse waveform in one cycle of the ejection drive signal. 5. The liquid ejecting apparatus according to claim 4, wherein the liquid ejecting apparatus is in a relationship shifted backward in time with respect to at least a first pulse waveform of the liquid crystal. When the gradation data for the unit area is small dot data,
When the drive pulse train generated for the unit region immediately before the unit region includes the last pulse waveform within one cycle of the ejection drive signal, the drive pulse train generated by the drive pulse generator is one cycle. Drive pulse train including the third and fifth pulse waveforms,
When the drive pulse train generated for the unit region immediately before the unit region does not include the last pulse waveform in one cycle of the ejection drive signal, the drive pulse train generated by the drive pulse generator is one cycle. Drive pulse train including the second and fourth pulse waveforms,
When the gradation data for the unit area is data for minimal dots,
When the drive pulse train generated for the unit region immediately before the unit region includes the last pulse waveform within one cycle of the ejection drive signal, the drive pulse train generated by the drive pulse generator is one cycle. Drive pulse train including the fourth pulse waveform of
When the drive pulse train generated for the unit region immediately before the unit region does not include the last pulse waveform in one cycle of the ejection drive signal, the drive pulse train generated by the drive pulse generator is one cycle. The liquid ejecting apparatus according to claim 5, wherein the driving pulse train includes a third pulse waveform. A head member having a nozzle opening;
Pressure fluctuation means for changing the pressure of the liquid in the nozzle opening to discharge liquid droplets;
An ejected medium holding unit that holds the liquid ejected medium so as to face the nozzle openings of the head member and be separated from the nozzle openings by a substantially equal distance;
A moving mechanism for moving the head member relative to the liquid ejection medium;
Drive signal generating means for generating a plurality of ejection drive signals which are periodic signals having different pulse waveforms and the same period;
For each unit region of the liquid ejection medium, gradation data for the unit region, the plurality of ejection drive signals, and a drive pulse train generated for the unit region immediately before the unit region are the plurality of units. Drive pulse generation means for generating a drive pulse train based on information on whether or not it includes the last pulse waveform in any one cycle of the ejection drive signal;
A control body for driving the pressure fluctuation means based on the drive pulse;
With
One period of the plurality of ejection drive signals corresponds to one unit region of the liquid ejection medium. The gradation data includes data for small dots for forming small dots on the liquid ejection medium,
When the gradation data for the unit area is small dot data,
Drive generated by the drive pulse generation means when the drive pulse train generated for the unit area immediately before the unit area includes the last pulse waveform in one cycle of the plurality of ejection drive signals. When the pulse train includes at least the first pulse waveform of the drive pulse train generated for the unit region immediately before the unit region not including the last pulse waveform in one cycle of the plurality of ejection drive signals. 8. The liquid ejecting apparatus according to claim 7, wherein at least a first pulse waveform of a drive pulse train generated by the drive pulse generating unit is shifted backward in time. A head member having a nozzle opening;
Pressure fluctuation means for changing the pressure of the liquid in the nozzle opening to discharge liquid droplets;
An ejected medium holding unit that holds the liquid ejected medium so as to face the nozzle openings of the head member and be separated from the nozzle openings by a substantially equal distance;
A moving mechanism for moving the head member relative to the liquid ejection medium;
A control device for controlling a liquid ejecting apparatus comprising:
Drive signal generating means for generating an ejection drive signal which is a periodic signal having a plurality of pulse waveforms;
For each unit area of the liquid ejection medium, the gradation data for the unit area, the ejection drive signal, and the drive pulse train generated for the unit area immediately before the unit area are represented by the ejection drive signal. Drive pulse generating means for generating a drive pulse train based on whether or not the last pulse waveform in one cycle is included; and
A control body for driving the pressure fluctuation means based on the drive pulse;
With
One period of the ejection drive signal corresponds to one unit region of the liquid ejection medium. The gradation data includes data for small dots for forming small dots on the liquid ejection medium,
When the gradation data for the unit area is small dot data,
When the drive pulse train generated for the unit region immediately before the unit region includes the last pulse waveform within one cycle of the ejection drive signal, at least the first drive pulse train generated by the drive pulse generator The pulse waveform is a drive pulse train generated by the drive pulse generator when the drive pulse train generated for the unit region immediately before the unit region does not include the last pulse waveform in one cycle of the ejection drive signal. The control device according to claim 9, wherein the control device is in a relationship shifted backward in time with respect to at least the first pulse waveform. The control apparatus according to claim 9 or 10, wherein the ejection drive signal is a periodic signal having a plurality of pulse waveforms having the same shape within one period. The control apparatus according to claim 11, wherein the ejection driving signal is a periodic signal having five pulse waveforms having the same shape within one period. The gradation data includes data for small dots for forming small dots on the liquid ejection medium, and data for minimal dots for forming minimal dots on the liquid ejection medium,
When the gradation data for the unit area is small dot data,
When the drive pulse train generated for the unit region immediately before the unit region includes the last pulse waveform within one cycle of the ejection drive signal, at least the first drive pulse train generated by the drive pulse generator The pulse waveform is a drive pulse train generated by the drive pulse generator when the drive pulse train generated for the unit region immediately before the unit region does not include the last pulse waveform in one cycle of the ejection drive signal. In relation to at least the first pulse waveform of
When the gradation data for the unit area is data for minimal dots,
When the drive pulse train generated for the unit region immediately before the unit region includes the last pulse waveform within one cycle of the ejection drive signal, at least the first drive pulse train generated by the drive pulse generator The pulse waveform is a drive pulse train generated by the drive pulse generator when the drive pulse train generated for the unit region immediately before the unit region does not include the last pulse waveform in one cycle of the ejection drive signal. The control device according to claim 12, wherein at least the first pulse waveform is in a relationship shifted backward in time. When the gradation data for the unit area is small dot data,
When the drive pulse train generated for the unit region immediately before the unit region includes the last pulse waveform within one cycle of the ejection drive signal, the drive pulse train generated by the drive pulse generator is one cycle. Drive pulse train including the third and fifth pulse waveforms,
When the drive pulse train generated for the unit region immediately before the unit region does not include the last pulse waveform in one cycle of the ejection drive signal, the drive pulse train generated by the drive pulse generator is one cycle. Drive pulse train including the second and fourth pulse waveforms,
When the gradation data for the unit area is data for minimal dots,
When the drive pulse train generated for the unit region immediately before the unit region includes the last pulse waveform within one cycle of the ejection drive signal, the drive pulse train generated by the drive pulse generator is one cycle. Drive pulse train including the fourth pulse waveform of
When the drive pulse train generated for the unit region immediately before the unit region does not include the last pulse waveform in one cycle of the ejection drive signal, the drive pulse train generated by the drive pulse generator is one cycle. The control device according to claim 13, wherein the control pulse train includes a third pulse waveform. A head member having a nozzle opening;
Pressure fluctuation means for changing the pressure of the liquid in the nozzle opening to discharge liquid droplets;
An ejected medium holding unit that holds the liquid ejected medium so as to face the nozzle openings of the head member and be separated from the nozzle openings by a substantially equal distance;
A moving mechanism for moving the head member relative to the liquid ejection medium;
A control device for controlling a liquid ejecting apparatus comprising:
Drive signal generating means for generating a plurality of ejection drive signals which are periodic signals having different pulse waveforms and the same period;
For each unit region of the liquid ejection medium, gradation data for the unit region, the plurality of ejection drive signals, and a drive pulse train generated for the unit region immediately before the unit region are the plurality of units. Drive pulse generation means for generating a drive pulse train based on information on whether or not it includes the last pulse waveform in any one cycle of the ejection drive signal;
A control body for driving the pressure fluctuation means based on the drive pulse;
With
One period of the plurality of ejection drive signals corresponds to one unit region of the liquid ejection medium. The gradation data includes data for small dots for forming small dots on the liquid ejection medium,
When the gradation data for the unit area is small dot data,
Drive generated by the drive pulse generation means when the drive pulse train generated for the unit area immediately before the unit area includes the last pulse waveform in one cycle of the plurality of ejection drive signals. When at least the first pulse waveform of the pulse train does not include the last pulse waveform in one cycle of any of the plurality of ejection drive signals, the drive pulse train generated for the unit region immediately preceding the unit region 16. The control device according to claim 15, wherein the control device has a relationship shifted backward in time with respect to at least the first pulse waveform of the drive pulse train generated by the drive pulse generator.   A program that is executed by a computer system including at least one computer to cause the computer system to implement the control device according to any one of claims 9 to 16. Instructions for controlling a second program running on a computer system including at least one computer,
A program that is executed by the computer system to control the second program to cause the computer system to implement the control device according to any one of claims 9 to 16.

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