JP2008119840A - Liquid jet apparatus and its control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid jet apparatus which can prevent generation of mist in frameless recording, and to provide its control method. <P>SOLUTION: A drive signal generating circuit is constituted to generate a first drive signal COM1 which includes a first ejection pulse DP1, and a second drive signal COM2 which includes a second ejection pulse DP2 set to make a flying speed of ejected ink droplets different from that of the first ejection pulse. The first ejection pulse DP1 in the first drive signal COM1 is selected and supplied to a piezoelectric vibrator at the ejection of the ink droplets to a theoretical recording region on a sheet of recording paper. Further, the second ejection pulse DP2 in the second drive signal COM2 is selected and supplied to the piezoelectric vibrator at the time of ejection of the ink droplets to a protruding region set exceeding an end of the recording region outside. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a liquid ejecting apparatus such as an ink jet printer, and a control method thereof, and in particular, a liquid ejecting apparatus capable of so-called borderless recording that performs recording without a margin on a recording surface of a recording medium, and It relates to the control method.

  The liquid ejecting apparatus is an apparatus that includes a liquid ejecting head capable of ejecting liquid as droplets and ejects various liquids from the liquid ejecting head. As a typical example of this liquid ejecting apparatus, for example, an ink jet printer (hereinafter referred to as an ink jet printer) that performs recording by forming dots by ejecting and landing liquid ink as ink droplets on recording paper or the like as a recording medium. And an image recording apparatus such as a printer. In recent years, the present invention is applied not only to this image recording apparatus but also to various manufacturing apparatuses such as a display manufacturing apparatus.

  Here, a recording method (so-called borderless recording) is proposed for the above-described ink jet printer (hereinafter simply abbreviated as “printer”) on a recording surface of a recording medium (for example, recording paper) with no margin. (For example, refer to Patent Document 1). In borderless recording, image data is developed and recorded (ink droplet ejection operation) in an image development area (recording area virtually set for the recording medium) of the same size as the actual size of the recording medium. Then, a margin is generated in a part of the recording surface due to a conveyance error or an inclination of the recording medium. Therefore, in borderless recording, recording is executed by developing digital image data in an image development area slightly larger than the size of the recording medium.

Japanese Patent Laid-Open No. 2002-103586

  In the above configuration, an area for collecting unnecessary ink droplets ejected outside the recording surface of the recording paper in borderless recording (for example, on the platen that supports the recording paper so as to face the recording head (for example, A portion filled with an ink absorbing material).

  However, the amount of ink droplets for small dots used to achieve high image quality is as small as several pL, for example. This very small amount of ink droplets is strongly subjected to the viscous resistance of air, so that the flightable distance is very short. For this reason, if only the ink absorbing material is provided on the platen, there is a possibility that some ink droplets do not reach the ink absorbing material and become mist in borderless recording. In addition to the ink droplets for the small dots described above, there are cases where minute ink droplets called satellite ink droplets are generated accompanying the ink droplets in the main body, and these satellite ink droplets are used as ink absorbers. There is also the possibility of mist without reaching. The misted ink not only contaminates the inside of the recording paper and the printer, but also adheres to electronic parts such as a circuit board and may cause a failure such as a short circuit.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a liquid ejecting apparatus capable of preventing the occurrence of mist in borderless recording, and a control method thereof. .

The liquid ejecting apparatus of the present invention has been proposed in order to achieve the above object, and a series of liquid flow paths including a pressure chamber and a nozzle opening, and pressure generation that causes pressure fluctuation in the liquid in the pressure chamber. A liquid ejecting head that ejects liquid droplets from the nozzle openings by driving the pressure generating means;
A drive signal generating means capable of repeatedly generating a plurality of drive signals including discharge pulses for driving the pressure generating means to discharge droplets;
Drive control means for selecting a discharge pulse in the drive signal generated by the drive signal generating means and supplying the selected discharge pulse to the pressure generating means;
A liquid ejecting apparatus comprising:
The drive signal generating means includes
Generating a first drive signal including a first discharge pulse, and a second drive signal including a second discharge pulse set so that a flying speed of a discharged droplet is different from the first discharge pulse;
The drive control means selects and supplies the first ejection pulse in the first drive signal to the pressure generating means when ejecting droplets to the theoretical recording area of the recording medium, while the outside of the recording area The second ejection pulse in the second drive signal is selected and supplied to the pressure generating means when ejecting droplets to the protruding region set to.
Note that the “theoretical recording area” means a recording area on a virtual (designed) recording medium assuming that no positional deviation occurs.

  According to this configuration, the first ejection pulse is used when the droplet is ejected to the theoretical recording area of the recording medium, while the second ejection pulse is used when the droplet is ejected to the ejection area. The generation of mist can be suppressed when the liquid droplets are discharged. For example, if the second ejection pulse is set so that the droplet flying speed when the droplet is ejected using the second ejection pulse can be reliably landed by the droplet absorber, It is possible to suppress the occurrence of mist when discharging droplets beyond the edge.

  In the above configuration, it is desirable that the first ejection pulse and the second ejection pulse are set so that the amount of ejected droplets is uniform.

  According to this configuration, since the amount of liquid droplets ejected in the protruding area and the theoretical recording area is uniform, it is possible to prevent the image quality of the recorded image from greatly differing between the two.

  Further, in the above configuration, the second ejection pulse has a configuration in which the level of the droplet flying speed relative to the droplet flying speed during ejection by the first ejection pulse is determined according to the size of the droplet during ejection. It is desirable to adopt.

  According to this configuration, for example, when the size of the ejected droplet is relatively small and the droplet itself is likely to mist, the droplet flying speed during ejection by the second ejection pulse is determined to be high. In this case, the droplet can be landed on the droplet absorbing material provided at the position corresponding to the protruding region without being misted. On the other hand, when using large droplets that can sufficiently land on the droplet absorbing material provided at the position corresponding to the protruding region without increasing the flying speed, the liquid at the time of ejection by the second ejection pulse is used. By setting the droplet flying speed low, the generation of satellite droplets can be suppressed. Thereby, mist can be suppressed irrespective of the size of the droplets at the time of ejection.

In the above-described configuration, an end detection means for detecting an end in a direction orthogonal to the conveyance direction of the recording medium is provided,
The drive control unit may employ a configuration for determining the protruding region based on a detection signal from the end detection unit.

  Further, a configuration may be adopted in which the drive control unit determines the protrusion area based on data corresponding to the protrusion area in the discharge data developed for discharging a droplet.

Further, the control method of the liquid ejecting apparatus of the present invention includes a series of liquid flow paths including a pressure chamber and a nozzle opening, and pressure generating means for causing pressure fluctuation in the liquid in the pressure chamber, and the pressure generating means A liquid jet head that discharges droplets from the nozzle openings by driving
A drive signal generating means capable of repeatedly generating a plurality of drive signals including discharge pulses for driving the pressure generating means to discharge droplets;
Drive control means for selecting a discharge pulse in the drive signal generated by the drive signal generating means and supplying the selected discharge pulse to the pressure generating means;
A control method of a liquid ejecting apparatus comprising:
Including the first ejection pulse in the first drive signal, and the second drive signal including the second ejection pulse set so that the flying speed of the ejected droplet is different from the first ejection pulse;
The first ejection pulse in the first drive signal is selected and supplied to the pressure generating means when ejecting droplets to the theoretical recording area in the recording medium, while the protruding area set outside the recording area The second ejection pulse in the second drive signal is selected and supplied to the pressure generating means when the droplet is ejected to the pressure.

  According to this configuration, the first ejection pulse is used when the droplet is ejected to the theoretical recording area of the recording medium, while the second ejection pulse is used when the droplet is ejected to the ejection area. The generation of mist can be suppressed when the liquid droplets are discharged. For example, if the second ejection pulse is set so that the droplet flying speed when the droplet is ejected using the second ejection pulse can be reliably landed by the droplet absorber, It is possible to suppress the occurrence of mist when discharging droplets beyond the edge.

  In the above configuration, it is desirable that the first ejection pulse and the second ejection pulse are set so that the amount of ejected droplets is uniform.

  According to this configuration, since the amount of liquid droplets ejected in the protruding area and the theoretical recording area is uniform, it is possible to prevent the image quality of the recorded image from greatly differing between the two.

  Further, in the above configuration, the second ejection pulse has a configuration in which the level of the droplet flying speed relative to the droplet flying speed during ejection by the first ejection pulse is determined according to the size of the droplet during ejection. It is desirable to adopt.

  According to this configuration, for example, when the size of the ejected droplet is relatively small and the droplet itself is likely to mist, the droplet flying speed during ejection by the second ejection pulse is determined to be high. In this case, the droplet can be landed on the droplet absorbing material provided at the position corresponding to the protruding region without being misted. On the other hand, when using large droplets that can sufficiently land on the droplet absorbing material provided at the position corresponding to the protruding region without increasing the flying speed, the liquid at the time of ejection by the second ejection pulse is used. By setting the droplet flying speed low, the generation of satellite droplets can be suppressed. Thereby, mist can be suppressed irrespective of the size of the droplets at the time of ejection.

  In the above configuration, it is possible to employ a configuration in which the protruding area is determined based on a detection signal of an end detection means for detecting an end in a direction orthogonal to the conveyance direction of the recording medium.

  Further, a configuration may be adopted in which the protruding area is determined based on data corresponding to the protruding area in the discharge data developed for discharging the droplet.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings. In the following, an ink jet printer (hereinafter abbreviated as a printer) shown in FIG. 1 is illustrated as an example of the liquid ejecting apparatus of the present invention.

  First, the overall configuration of the printer will be described. Here, FIG. 1 is a plan view showing a schematic structure of the printer, and FIG. 2 is a schematic side view of the inside of the printer. As shown in these drawings, the printer 1 includes a paper feeding unit 3 that feeds a recording paper 2 that is a kind of recording medium (a droplet discharge target), and an image or the like on the fed recording paper 2. A recording unit 4 that performs recording and a paper discharge unit 5 that transports the recorded recording paper 2 in the paper discharge direction are provided.

  The paper feeding unit 3 is provided in the rear portion of the printer 1. The paper feed unit 3 includes a support plate 6 that can support a plurality of recording papers 2 in a stacked state, a paper feed roller 7 that feeds the recording paper 2 on the support plate 6 to the recording unit 4 side by friction, And a guide plate 8 for guiding the recording paper 2 fed by the paper feeding roller 7 to the recording unit 4 side. Note that so-called roll paper wound around the surface of the cylindrical core material can also be supplied from the paper supply unit 3. In this case, for example, a separate roll paper holder (not shown) is attached to the paper feeding unit 3.

  The support plate 6 is provided with a pair of left and right edge guides 9 that regulate the position in the width direction of the recording paper 2 by contacting the left and right side edges (that is, the left and right edge portions) of the recording paper 2. . That is, the edge guide 9 includes a right edge guide 9A located on the right side when viewed from the front of the printer 1 and a left edge guide 9B located on the left side.

  In the present embodiment, the right edge guide 9A is provided integrally with the support plate 6 at the right end of the support plate 6, and the left edge guide 9B is disposed so as to be movable in the left-right direction, which is the recording width direction. For this reason, the support plate 6 is provided with a guide groove portion 10 in which a mounting base portion (not shown) of the left edge guide 9B is fitted in the left-right direction, and the left edge guide 9B extends along the guide groove portion 10. It is attached so as to be movable in the recording width direction. Then, the user moves the left edge guide 9B in the left-right direction according to the paper width of the recording paper 2 to be used, and the guide surfaces of both edge guides 9A, 9B are brought into contact with the side edges of the recording paper 2, thereby supporting The left and right positions of the recording paper 2 supported on the plate 6 are restricted. Accordingly, the position of the recording paper 2 with a plurality of sizes standardized from a postcard size to an A4 size, for example, can be regulated by the pair of edge guides 9A and 9B.

  A rotation shaft of a paper feed motor 11 (see FIG. 3) is connected to the paper feed roller 7, and the paper feed roller 7 is rotated by a driving force of the paper feed motor 11. When the paper feeding roller 7 rotates, the recording paper 2 positioned at the top of the plurality of recording papers 2 supported on the support plate 6 comes into contact with the surface of the paper feeding roller 7, and the paper feeding roller 7 7 is rotated and supplied to the recording unit 4.

  The recording unit 4 is provided with a holding unit that detachably holds a liquid supply source such as an ink cartridge and the carriage 17 to which the recording head 16 is attached, and the carriage 17 along the main scanning direction that is the recording width direction. A guide shaft 18 for guiding, a paper feeding mechanism for transporting the recording paper 2, a carriage scanning mechanism for moving the carriage 17 along the guide shaft 18, and the recording paper 2 fed by the paper feeding mechanism opposite to the recording surface A platen 20 supported from the side and opposed to the nozzle surface of the recording head 16, and an ink droplet absorber 21 (droplet) provided on the surface of the platen 20 for absorbing ink droplets ejected outside the recording paper Absorber).

  FIG. 4 is a cross-sectional view of a main part for explaining the configuration of the recording head 16. The recording head 16 in the present embodiment includes a vibrator unit 26 in which the piezoelectric vibrator 23, the fixing plate 24, the flexible cable 25, and the like are unitized, a case 27 that can store the vibrator unit 26, And a flow path unit 28 joined to the bottom surface.

  The case 27 is a hollow block-shaped member made of synthetic resin in which an empty portion for housing the vibrator unit 26 is formed. The vibrator unit 26 is housed and fixed in the housing space of the case 27 by bonding the fixing plate 24 to the inner wall surface. In this stored state, the front end surface of the piezoelectric vibrator 23 faces the opening on the bottom surface side of the empty portion, and is joined to the island portion 29 of the flow path unit 28 as described later.

  The piezoelectric vibrator 23 is a kind of pressure generating means in the present invention, and in this embodiment, it is formed in a comb-teeth shape cut into an extremely narrow width of about several tens of μm to 100 μm. Each piezoelectric vibrator 23 is attached in a cantilever state in which a free end portion is projected outward from the edge of the fixed plate 24. The piezoelectric vibrator 23 is a laminated piezoelectric vibrator configured by alternately laminating piezoelectric bodies and internal electrodes, and is a type of piezoelectric vibrator capable of expanding and contracting in a vertical direction perpendicular to the electric field direction. . Then, the free end of the piezoelectric vibrator 23 contracts in the longitudinal direction of the vibrator by charging, and the free end shrinks in the longitudinal direction of the element by discharging. The flexible cable 25 is electrically connected to each piezoelectric vibrator 23 at the base end of the vibrator, and supplies a drive signal from the printer controller 12 side to each piezoelectric vibrator 23.

  The flow path unit 28 has a nozzle plate (nozzle forming substrate) 30 disposed on one surface of the flow path forming substrate 31 and a vibration plate 32 disposed on the other surface opposite to the nozzle plate 30 for bonding or the like. It is comprised by integrating by. The nozzle plate 30 is a thin plate made of stainless steel in which a plurality of nozzle openings 33 are opened in a row at a pitch corresponding to the dot formation density. In the present embodiment, 360 nozzle openings 33 are opened at a pitch of 360 dpi, and these nozzle openings 33 constitute a nozzle row.

  The flow path forming substrate 31 is a plate-like member that is formed in a plurality in a state in which empty portions that become the pressure chambers 34 are partitioned by partition walls so as to correspond to the respective nozzle openings 33 of the nozzle plate 30. Further, in the flow path forming substrate 31 in the present embodiment, in addition to the empty portion that becomes the pressure chamber 34, the empty portion that becomes the ink supply port 35 and the reservoir 36 is formed. The flow path forming substrate 31 is produced, for example, by etching a silicon wafer or plastic processing a metal plate such as nickel. The pressure chamber 34 is configured as an elongated chamber in a direction orthogonal to the direction in which the nozzle openings 33 are arranged (nozzle row direction). A nozzle communication port 37 is provided at one end in the longitudinal direction of the pressure chamber 34 far from the reservoir 36 so as to penetrate the plate thickness direction, and the pressure chamber 34 and the nozzle opening 33 communicate with each other. The ink supply port 35 is a groove-like portion formed between the other end in the longitudinal direction of the pressure chamber 34 and the reservoir 36, and the flow path width thereof is sufficiently narrower than that of the pressure chamber 34.

  The diaphragm 32 has a double structure in which an elastic film made of a resin film such as PPS (polyphenylene sulfide) is laminated on a support plate such as stainless steel, and a diaphragm portion that seals one opening surface of the pressure chamber 34. And a compliance portion that seals one opening surface of the reservoir 36. The diaphragm portion is produced by etching the portion of the support plate 22 corresponding to the pressure chamber 34 in an annular shape, and an island portion 29 is formed in the ring. Further, the compliance portion is manufactured by removing the portion of the support plate 22 corresponding to the reservoir 36 by etching so that only the elastic film is formed.

  In the recording head 16 configured as described above, the island portion 29 is pressed toward the nozzle plate 30 by extending the piezoelectric vibrator 23 in the longitudinal direction of the vibrator. By this pressing, the elastic film constituting the diaphragm portion is deformed and the pressure chamber 34 is contracted. When the piezoelectric vibrator 23 is contracted in the longitudinal direction of the vibrator, the pressure chamber 34 expands due to the elasticity of the elastic film. Since the internal ink pressure fluctuates due to expansion and contraction of the pressure chamber 34, an ink droplet (a kind of droplet of the present invention) can be ejected from the nozzle opening 33 by controlling the expansion and contraction.

  The liquid ejecting head in the present invention is not limited to the exemplified recording head 1, and various configurations can be employed. For example, in the illustrated recording head 1, a so-called longitudinal vibration mode piezoelectric vibrator 23 is used as a pressure generating unit. Instead of the piezoelectric vibrator 23, a so-called flexural vibration mode piezoelectric vibrator is used. The recording head to be used can also be adopted. Further, for example, a recording head configured to eject an ink droplet by elastically deforming an elastic surface that partitions the pressure chamber by an electrostatic force generated between the counter electrodes may be employed.

  In the printer 1, the paper feed mechanism for transporting the recording paper 2 in the paper feed direction perpendicular to the recording width direction includes a paper feed roller 40 shown in FIG. 2, a paper feed motor 41 shown in FIG. The printer controller 12 shown in FIG. As shown in FIG. 2, the paper feed roller 40 includes a driving roller 40A positioned on the lower side and a driven roller 40B positioned on the upper side. A rotation shaft of a paper feed motor 41 (see FIG. 3) is connected to the drive roller 40A, and the drive roller 40A is rotated by a driving force of the paper feed motor 41. The driven roller 40B rotates following the rotation of the drive roller 40A. The paper feed motor 41 is electrically connected to the printer controller 12, and the operation is controlled by a drive signal from the printer controller 12.

  The carriage scanning mechanism moves the carriage 17 in the main scanning direction. The carriage scanning mechanism of the present embodiment includes a pulse motor 42 shown in FIG. 3, a power transmission unit that moves the carriage 17 by the rotation of the pulse motor 42, and a printer controller 12 that controls the operation of the pulse motor 42. The The power transmission unit can have any configuration, but is provided on one end of the printer 1 on the left and right ends, for example, and connected to the rotating shaft of the pulse motor 42 and on the other end on the left and right of the printer 1. And a timing belt that is spanned between the drive pulley and the idle pulley and connected to the carriage 17. In this carriage scanning mechanism, the recording head 16 can be moved in a range wider than the width of the maximum recordable recording paper 2.

  The ink droplet absorbing material 21 is disposed on the back side of the recording paper 2 immediately below the scanning area of the recording head 16. The ink droplet absorbing material 21 is disposed on the surface of the platen 20 that supports the recording paper 2 from below, and on the rear side (upstream side in the paper feed direction) of the platen 20 is a paper feed roller 40 of the paper feed mechanism. (40A, 40B) are arranged, and on the front side of the platen 20 (downstream in the paper feeding direction), a driving roller 43A and a paper pressing roller 43B that constitute the paper discharge roller 43 of the paper discharge unit 5 are arranged. ing. That is, the recording paper 2 is guided from the paper supply unit 3 to the platen 20 of the recording unit 4 by the paper feed roller 40, and after the printing operation of the recording head 16 on the platen 20 is completed, the recording unit 4 is output by the paper discharge roller 43. The platen 20 is sequentially guided to the paper discharge unit 3. The ink droplet absorbing material 21 is disposed at a position lower than the height through which the recording paper 2 passes.

  The recording head 16 in the present embodiment is provided with a paper width sensor 45 (a kind of edge detection means; see FIG. 3). The recording width of the recording paper 2 supplied onto the platen 20 by the paper width sensor 45 is provided. The positions of both ends in the main scanning direction are detected. The paper width sensor 45 is composed of a non-contact optical sensor, and the detection signal is output to the control unit 55 of the printer controller 12 shown in FIG. The control unit 55 can recognize the paper width of the recording paper 2 based on the detection signal from the paper width sensor 45.

  The platen 20 is a plate-like member, and a plurality of diamond ribs 46 functioning as support protrusions are provided in parallel on the surface of the platen 20 at predetermined intervals along the moving direction of the recording head 16. Each diamond rib 46 protrudes upward from the platen surface, and the upper surface thereof serves as a contact surface for supporting the recording paper 2, and the recording paper 2 is partially supported by each diamond rib 46.

  The ink droplet absorbing material 21 includes a front end ink droplet absorbing material 21a laid on the downstream side of the row of diamond ribs 46 in the paper feed direction on the platen 20, and a trailing edge ink droplet absorbing material 21b laid on the upstream side. , And side edge ink droplet absorbers 21c, 21d, and 21e arranged at positions corresponding to the left and right side edges of the recording paper with standardized left and right widths. As the ink droplet absorbing material 21, for example, a porous member having good liquid absorbability made of felt, sponge, or the like can be used.

  The arrangement of the side edge ink droplet absorbing materials 21c, 21d, and 21e will be described in detail. Portions corresponding to the sheet width edges (right edge and left edge) of the recording sheets 2A and 2B having different sizes; That is, the side edge ink droplet absorbing material 21c is elongated along the paper feed direction (the side edge direction of the recording paper) on the outer side (right side in FIG. 1) of the diamond rib 46A that supports the right edge of each recording paper 2A, 2B. The side edge ink droplet absorbing material 21d is elongated along the paper feed direction outside the diamond rib 46B that supports the left side edge of the narrow recording paper 2A (to the left in FIG. 1), and wide recording is performed. A side edge ink droplet absorbent 21e is elongated along the paper feed direction on the outer side (left side in FIG. 1) of the diamond rib 46C that supports the left side edge of the paper 2B.

  FIG. 3 is a block diagram showing an electrical configuration of the printer 1. The printer 1 is roughly composed of a printer controller 12 and a print engine 51. The printer controller 12 includes an external interface (external I / F) 52 that exchanges data with an external device such as a host computer, a RAM 53 that stores various data, a control routine for various data processing, and the like. The stored ROM 54, a control unit 55 for controlling each unit, an oscillation circuit 56 for generating a clock signal, a drive signal generation circuit 58 for generating a drive signal to be supplied to the recording head 16, dot pattern data, a drive signal, etc. Is provided to the recording head 16 and an internal interface (internal I / F) 57 is provided.

  The control unit 55 controls each unit, converts print data received from the external device through the external I / F 52 into dot pattern data, and outputs the dot pattern data to the recording head 16 side through the internal I / F 57. . This dot pattern data is constituted by print data obtained by decoding (translating) gradation data. The control unit 55 supplies a latch signal, a channel signal, and the like to the recording head 16 based on a clock signal from the oscillation circuit 56. The latch pulses and channel pulses included in these latch signals and channel signals define the supply timing of each pulse constituting the drive signal.

  The drive signal generation circuit 58 (drive signal generation means) is controlled by the control unit 55 and generates a drive signal for driving the piezoelectric vibrator 23. The drive signal generation circuit 58 in the present embodiment includes a drive signal (first drive signal COM1) that includes an ejection pulse for ejecting ink droplets to form dots on the recording paper 2 within one recording period (one ejection period). , The second drive signal COM2). As shown in FIG. 5, the first drive signal COM1 is a signal having a first ejection pulse DP1, and is repeatedly generated at every recording cycle. On the other hand, the second drive signal COM2 is a signal having a second ejection pulse DP2 set so that the flying speed of the ejected ink droplet is different from the first ejection pulse DP1. The drive signals COM1 and COM2 will be described in detail later.

  Next, the configuration on the print engine 51 side will be described. The print engine 51 includes a recording head 16, a paper feed motor 11, a paper discharge motor 30, a paper feed motor 41, a pulse motor 42, and a paper width sensor 45. The recording head 16 includes a shift register (SR) 60, a latch 61, a decoder 62, a level shifter 63, a switch 64, and the piezoelectric vibrator 23. The dot pattern data (SI) from the printer controller 12 is serially transmitted to the shift register 60 in synchronization with the clock signal (CK) from the oscillation circuit 56.

  A latch 61 is electrically connected to the shift register 60. When a latch signal (LAT) from the printer controller 12 is input to the latch 61, the dot pattern data in the shift register 60 is latched. The dot pattern data latched by the latch 61 is input to the decoder 62. The decoder 62 translates 2-bit dot pattern data to generate pulse selection data. This pulse selection data is constituted by associating each bit with each pulse constituting the drive signal COM. Then, supply or non-supply of the ejection pulse to the piezoelectric vibrator 23 is selected according to the contents of each bit, for example, “0” and “1”.

  Then, the decoder 62 outputs pulse selection data to the level shifter 63 when receiving the latch signal (LAT) or the channel signal (CH). In this case, the pulse selection data is input to the level shifter 63 in order from the upper bit. The level shifter 63 functions as a voltage amplifier. When the pulse selection data is “1”, the level shifter 63 outputs an electric signal boosted to a voltage capable of driving the switch 64, for example, a voltage of about several tens of volts. The pulse selection data “1” boosted by the level shifter 63 is supplied to the switch 64. The drive signal COM from the drive signal generation circuit 58 is supplied to the input side of the switch 64, and the piezoelectric vibrator 23 is connected to the output side of the switch 64.

  The pulse selection data controls the operation of the switch 64, that is, the supply of the drive pulse in the drive signal to the piezoelectric vibrator 23. For example, during a period in which the pulse selection data input to the switch 64 is “1”, the switch 64 is in a connected state, and the corresponding ejection pulse is supplied to the piezoelectric vibrator 23 and follows the waveform of the ejection pulse. Thus, the potential level of the piezoelectric vibrator 23 changes. On the other hand, during the period when the pulse selection data is “0”, the level shifter 63 does not output an electrical signal for operating the switch 64. For this reason, the switch 64 is in a disconnected state, and no ejection pulse is supplied to the piezoelectric vibrator 23. The first drive signal COM1 and the second drive signal COM2 are supplied to the input side of the switch 64, and switching between supply / non-supply of the first drive signal COM1 or the second drive signal COM2 to the piezoelectric vibrator 23 is performed. It is configured as follows.

  The decoder 62, the level shifter 63, the switch 64, and the control unit 55 that perform such an operation function as drive control means in the invention, and based on the dot pattern data, the first drive signal COM1 or the second drive signal COM2 is selected. A required ejection pulse DP is selected and applied (supplied) to the piezoelectric vibrator 23. As a result, the piezoelectric vibrator 23 expands or contracts, and the pressure chamber 34 (see FIG. 2) expands or contracts in accordance with the expansion / contraction of the piezoelectric vibrator 23, so that it corresponds to the gradation information constituting the dot pattern data. A sufficient amount of ink droplets are ejected from the nozzle openings.

Next, borderless recording in which the printer 1 records an image with no margin on the recording surface of the recording paper 2 will be described.
FIG. 6 is a schematic diagram showing a theoretical recording area (hereinafter simply referred to as a recording area) PF during borderless recording and a protruding area OF set outside the recording area PF. The recording area PF is an area that is set after discriminating the standard sizes such as A4 and B5 of the recording paper 2 to be recorded according to the detection signal of the paper width sensor 45. In this embodiment, the recording area PF It is aligned to the actual size. Here, in the case of borderless recording, when dot pattern data is developed and recorded in the same size as the actual size of the recording paper (in this embodiment, the same size as the recording area PF), FIG. As indicated by the broken line, if the recording paper 2 is conveyed onto the platen 20 in an inclined state, a margin may be generated on a part of the recording surface. Therefore, in the printer 1, when performing borderless recording, the dot pattern data is developed in an area (image development area) slightly larger than the actual size of the recording paper. In the present embodiment, an area set beyond the end of the recording area PF is defined as a protruding area OF. The size (the amount of protrusion) of the protrusion area OF at the time of borderless recording can be automatically set to, for example, a predetermined specified amount, or a printer on the personal computer side connected to the printer 1 It is possible for the user to arbitrarily adjust with a driver or the like.

  In borderless recording, the protruding area OF is set as described above, and control is performed so that ink droplets are ejected also to the protruding area OF, so that there is no margin on the recording surface even when the recording paper 2 is slightly inclined. Images can be recorded. In this case, ink droplets are partially ejected toward the ink droplet absorbing material 21 beyond the end portion of the recording paper 2. In this marginless recording, the control unit 55 can determine the scanning position of the head corresponding to the protruding area OF based on the detection signal of the paper width sensor 45. Note that the scanning position corresponding to the protruding area OF can also be determined based on the data corresponding to the protruding area in the dot pattern data. That is, when discharging is performed based on the data, the control unit 55 can recognize that the discharging operation is performed on the protruding area OF.

  By the way, as shown in FIG. 7, when ink droplets are ejected from the recording head 16 onto the recording surface of the recording paper 2, the ink droplets are directed toward the ink droplet absorbing material 21 beyond the end of the recording paper 2. The flying distance of ink droplets differs from the case of ejection. That is, the distance D2 from the nozzle formation surface of the recording head 16 to the ink droplet absorbing material 21 is longer than the distance D1 from the nozzle formation surface (nozzle plate 30) of the recording head 16 to the recording surface of the recording paper 2. Usually, the flying speed of the ink droplets ejected from the recording head 16 is determined so as to be able to land on the recording surface of the recording paper 2, so that it is directed toward the ink droplet absorbing material 21 beyond the end of the recording paper 2. In the case of ejecting ink droplets, the ink droplets or satellite ink droplets (satellite droplets) accompanying the ink droplets may be misted before landing on the ink droplet absorbent 21. However, simply increasing the speed of the ink droplets as a whole to prevent mist formation will result in a decrease in ejection stability, such as the possibility of flying bends at high ink droplet speeds. In the case of continuous printing, the image quality of the recorded image may be deteriorated.

  Therefore, in the printer 1 according to the present invention, the above problem is solved by using different ejection pulses DP for ejecting ink droplets in the recording area PF and the protruding area OF. Hereinafter, this point will be described.

  FIG. 5 is a waveform diagram illustrating the configuration of the ejection pulses of the drive signals COM1 and COM2 generated by the drive signal generation circuit 58. In FIG. The first ejection pulse DP1 included in the first drive signal COM1 is a first preliminary expansion element P11 that increases the potential with a constant gradient from the reference potential VB to the maximum potential VH, and a rear end potential of the first preliminary expansion element P11. A first expansion hold element P12 that maintains the maximum potential VH for a certain period of time, a first discharge element P13 that drops the potential with a relatively steep gradient from the maximum potential VH to the minimum potential VL, and a first expansion element that maintains the minimum potential VL for a certain period of time. 1 contraction hold element P14 and 1st return expansion element P15 which returns an electric potential with a fixed gradient from lowest electric potential VL to reference electric potential VB.

  The second ejection pulse DP2 of the second drive signal COM2 is composed of the same waveform elements as the first ejection pulse DP1, and is a second preliminary that raises the potential with a constant gradient from the reference potential VB to the maximum potential VH. The expansion element P21, the second expansion hold element P22 that maintains the maximum potential VH that is the rear end potential of the second preliminary expansion element P21 for a certain time, and the potential with a relatively steep gradient from the maximum potential VH to the minimum potential VL. The second discharge element P23 to be lowered, the second contraction hold element P24 that maintains the minimum potential VL for a certain period of time, and the second return expansion element P25 that returns the potential with a constant gradient from the minimum potential VL to the reference potential VB. ing.

  When the ejection pulses DP1 and DP2 are supplied to the piezoelectric vibrator 23, they operate as follows. First, when the pre-expansion elements P11 and P21 are supplied to the piezoelectric vibrator 23, the piezoelectric vibrator 23 contracts, and accordingly, the pressure chamber 34 rises from the reference volume corresponding to the reference potential VB to the highest potential VH (VH). ) To a volume corresponding to. As a result, the meniscus is drawn into the pressure chamber and ink is supplied from the reservoir 36 into the pressure chamber 34 through the ink supply port 35. The expansion state of the pressure chamber 34 is maintained constant throughout the supply period of the expansion hold elements P12 and P22.

  When the discharge elements P13 and P23 are supplied to the piezoelectric vibrator 23 subsequent to the expansion hold elements P12 and P22, the piezoelectric vibrator 23 expands, so that the pressure chamber 34 reaches the minimum from the volume corresponding to the maximum potential VH. It contracts rapidly to the volume corresponding to the potential VL. The ink in the pressure chamber 34 is pressurized by the rapid contraction of the pressure chamber 34, and thereby ink droplets of several pl to several tens of pl are ejected. The contraction state of the pressure chamber 34 is maintained for a short time over the supply period of the contraction hold elements P14 and P24, and then the return expansion elements P15 and P25 are supplied to the piezoelectric vibrator 23 so that the pressure chamber 34 has the lowest potential. It returns from the volume corresponding to VL to the reference volume corresponding to the reference potential VB.

  As described above, the first discharge pulse DP1 and the second discharge pulse DP2 have the same basic function for discharging ink droplets. However, the two are set so that the flying speeds of the ink droplets discharged by supplying the piezoelectric vibrator 23 are different. In the present embodiment, in order to surely land the ink droplet when ejected using the second ejection pulse DP2 in borderless recording by the ink droplet absorber 21, the flying speed of the ink droplet is the first ejection pulse DP1. Is set so as to be faster than the flying speed of the ink droplets when ejected using. The drive control means selects the first ejection pulse DP1 when ejecting ink droplets to the recording area PF, and selects the second ejection pulse when ejecting ink drops to the protruding area OF. To do. Thereby, when ejecting ink droplets beyond the recording paper 2, the ink droplets can be landed reliably by the ink droplet absorbing material 21, and as a result, generation of mist can be suppressed. Further, by limiting the use of the second ejection pulse having a high ink droplet flying speed only to the protruding area OF, ejection stability can be ensured in ejecting ink droplets to the recording area PF.

  Here, the second ejection pulse DP2 is set so that only the flying speed is different from the first ejection pulse DP1 without changing the liquid amount (weight / volume) of the ejected ink droplets. In the present embodiment, the ratio between the generation time (supply time to the piezoelectric vibrator 23) t21 of the second preliminary expansion element P21 and the generation time t22 of the second expansion hold element P22 is set as the first preliminary pulse DP1. The flying speed of the ink droplets is adjusted by changing the generation times t21 and t22 while keeping the ratio between the generation time t11 of the expansion element P11 and the generation time t22 of the first expansion hold element P12.

  Specifically, as shown in FIG. 8A, the generation time t11 of the first preliminary expansion element P11 of the first ejection pulse DP1 is 2.7 (μs), and the first expansion hold element of the first ejection pulse DP1. While the generation time t12 of P12 is set to 3.0 (μs), the generation time t21 of the second preliminary expansion element P21 of the second discharge pulse DP2 is 2.5 (μs), and the second discharge pulse DP2 The generation time t22 of the second expansion hold element P22 is set to 2.8 (μs). In this example, the sum of the generation time t11 of the first preliminary expansion element P11 and the generation time t12 of the first expansion hold element P12 is 5.7 (μs), whereas the generation time t21 of the second preliminary expansion element P21. The total generation time t22 of the second expansion hold element P22 is as short as 5.3 (μs). Further, the ratio between the generation time of the preliminary expansion element and the expansion hold element, that is, t11: t12 and t21: t22 are both 9:10.

  After setting in this way, the appropriate drive voltage Va (the appropriate drive voltage Va1 of the first discharge pulse DP1 and the first drive pulse Va1 and the second discharge pulse DP2) are adjusted so that the liquid amounts of the ink droplets discharged are equalized. The appropriate driving voltage Va2) of the two ejection pulses DP2 is determined. Thus, the flying speed Vm2 of the ink droplet by the second ejection pulse DP2 can be increased by about 14% with respect to the flying speed Vm1 of the ink droplet by the first ejection pulse DP1. Further, since the liquid amounts of the ink droplets ejected in the protruding area OF and the recording area PF are uniform, it is possible to prevent the image quality of the recorded image from changing between the two. The appropriate drive voltages Va1 and Va2 are drive voltages set so that a prescribed amount of ink droplets are ejected, and are the potential difference between the highest potential VH and the lowest potential VL. The appropriate drive voltages Va1 and Va2 are determined based on the ink weight when ink droplets are actually ejected using each ejection pulse.

  By the way, depending on the size of the ink droplets to be ejected, in contrast to the above example, there may be a case where a better result is obtained when the flying speed is reduced. For example, in the case of an ink droplet of a large size that can be sufficiently landed on the ink droplet absorbing material 21 without increasing the flying speed, satellite ink droplets are likely to be generated if the flying speed is increased. In this case, it is preferable to keep the flying speed of the ink droplets low. For example, as illustrated in FIG. 8B, t21 is set to 2.9 (μs) and t22 is set to 3.2 (μs) while maintaining the ratio of t21 and t22 at 9:10 (t21 + t22 = 6.1 (μs)), when the appropriate drive voltage Va2 is determined, the flying speed Vm2 can be lowered by about 19% with respect to the flying speed Vm1. This can suppress the occurrence of satellite ink droplets when performing borderless recording by ejecting the large ink droplets. Therefore, it is possible to prevent the occurrence of mist based on the satellite ink droplets.

  As described above, when the size of the ejected ink droplet itself is relatively small and easily misted, the ink droplet flying speed Vm2 when ejected by the second ejection pulse DP2 is equal to the ink when ejecting by the first ejection pulse DP1. While the droplet flying speed Vm1 is set to be higher than the flying speed Vm1, the flying speed Vm2 is set when using a large-sized ink droplet that can sufficiently land on the ink droplet absorbent 21 without increasing the flying speed. By setting it to be low, mist at the time of borderless recording can be suppressed regardless of the size of the ink droplet at the time of ejection.

  By the way, in order to change the flying speed without changing the liquid amount of the ejected ink droplet, the configuration exemplified in the above embodiment is not limited. For example, the flying speed is adjusted by changing only the ratio of the generation time of the preliminary expansion element and the expansion hold element while keeping the total time of the generation time of the preliminary expansion element and the generation time of the expansion hold element constant. It is also possible (second embodiment).

  In the example shown in FIG. 9A, the generation time t11 of the first preliminary expansion element P11 of the first discharge pulse DP1 is 2.7 (μs), and the generation time t12 of the first expansion hold element P12 of the first discharge pulse DP1. Is set to 3.0 (μs), while the generation time t21 of the second preliminary expansion element P21 of the second ejection pulse DP2 is 3.7 (μs), and the second expansion hold of the second ejection pulse DP1 The generation time t22 of the element P22 is set to 2.0 (μs). In this example, the total time of t11 and t12 and the total time of t21 and t22 are both set to 5.7 (μs). In this way, by setting the second ejection pulse DP2 and determining the appropriate drive voltage Va2, the ink droplet flying speed Vm2 by the second ejection pulse DP2 is set to the first while aligning the liquid amount of the ejected ink droplet. The ink droplet flying speed Vm1 by the ejection pulse DP1 can be increased by about 27%. Also, as shown in FIG. 9B, t21 is set to 1.7 (μs) and t22 is set to 4.0 (μs) without changing the total time of t21 and t22 at 5.7 (μs). In addition, when the appropriate drive voltage Va2 is determined, the flying speed Vm2 can be reduced by 32% with respect to the flying speed Vm1 without changing the liquid amount of the ejected ink droplets.

  Also, the flying speed can be adjusted by changing only the ejection element generation time (third embodiment). For example, as shown in FIG. 10A, the generation time t13 of the first discharge element P13 of the first discharge pulse DP1 is set to 2.7 (μs), while the second discharge element P23 of the second discharge pulse DP2 is set. Is set to 2.2 (μs) and the appropriate drive voltage Va2 is determined, the ink droplet flying speed Vm2 by the second ejection pulse DP2 is set as the ink droplet flying speed by the first ejection pulse DP1. It was possible to increase 25% with respect to Vm1. Further, as shown in FIG. 10B, when the generation time t23 of the second ejection element P23 of the second ejection pulse DP2 is set to 3.2 (μs) and the appropriate drive voltage Va2 is determined, the flight speed Vm2 can be about 23% lower than the flight speed Vm1.

  Furthermore, only the generation time of the expansion hold element may be changed (fourth embodiment). For example, as shown in FIG. 11A, the generation time t12 of the first expansion hold element P12 of the first discharge pulse DP1 is set to 3.0 (μs), while the second expansion hold of the second discharge pulse DP2 is set. When the appropriate drive voltage Va2 is determined after setting the generation time t22 of the element P22 to 2.5 (μs), the flying speed Vm2 of the ink droplet by the second ejection pulse DP2 is set to the ink by the first ejection pulse DP1. The drop flying speed Vm1 can be increased by about 25%. Further, as shown in FIG. 11B, when the appropriate drive voltage Va2 is determined after setting the generation time t22 of the second expansion hold element P22 of the second ejection pulse DP2 to 3.5 (μs). The flying speed Vm2 can be reduced by about 31% with respect to the flying speed Vm1.

  It is also possible to adjust the flight speed by changing the reference potential without changing the generation time of each element (fifth embodiment). In the fifth embodiment, for example, as shown in FIGS. 12 and 13A, the reference potential VB of the first ejection pulse DP1 is set to 8.8 (V), whereas the second ejection is performed. The appropriate driving voltage Va2 is determined after raising the reference potential VB 'of the pulse DP2 to 12.5 (V). In this example, the ink droplet flying speed Vm2 by the second ejection pulse DP2 can be increased by about 3% with respect to the ink droplet flying speed Vm1 by the first ejection pulse DP1. On the other hand, as shown in FIG. 13B, when the appropriate drive voltage Va2 is determined with the intermediate potential VB 'set to 6.3 (V), the flying speed Vm2 is about 6% of the flying speed Vm1. Can be lowered.

  In addition, each numerical value quoted by each said embodiment is an illustration to the last, Comprising: It is not limited to these. By appropriately determining the generation time of the waveform element, the reference potential, and the like, it is possible to arbitrarily set the level of the ink droplet flying speed Vm2 by the second ejection pulse DP2 with respect to the ink droplet flying speed Vm1 by the first ejection pulse DP1. Is possible.

  In each of the above embodiments, the ejection pulses DP1 and DP2 shown in FIG. 5 are given as an example of the ejection pulse in the present invention, but the shape of the ejection pulse is not limited to this. Any discharge pulse having at least a preliminary expansion element, an expansion hold element, and a discharge element can be used.

  In the above embodiment, an example in which the theoretical recording area PF is aligned with the size of the recording paper is shown. However, the present invention is not limited to this, and the recording area PF having an arbitrary size is set based on the size of the recording paper. It is possible. For example, the protruding area OF can be increased by making the recording area PF smaller than the size of the recording paper. That is, in this case, since the area where the second ejection pulse DP2 used in the protruding area OF is used is widened, the generation of mist can be more reliably suppressed even if the recording paper is tilted.

  Furthermore, the present invention can be applied to apparatuses other than the above printer as long as the flying distance of the droplet (distance until landing on the discharge target) may change during the discharge operation. For example, the present invention can be applied to a display manufacturing apparatus, an electrode manufacturing apparatus, a chip manufacturing apparatus, and the like.

FIG. 2 is a plan view illustrating a configuration of a printer. It is a schematic side view inside a printer. 2 is a block diagram illustrating an electrical configuration of a printer. FIG. FIG. 3 is a cross-sectional view of a main part illustrating the configuration of a recording head. It is a wave form diagram explaining the structure of an ejection pulse. It is a schematic diagram explaining the theoretical recording area at the time of borderless recording, and the protrusion area set outside the recording area. FIG. 6 is a schematic diagram illustrating a difference between a distance from a nozzle surface of a recording head to a recording sheet and a distance from a nozzle surface of the recording head to an ink droplet absorbing material. (A), (b) is a figure explaining the experiment example in 1st Embodiment. (A), (b) is a figure explaining the experiment example in 2nd Embodiment. (A), (b) is a figure explaining the experiment example in 3rd Embodiment. (A), (b) is a figure explaining the experiment example in 4th Embodiment. It is a wave form diagram explaining the structure of the ejection pulse in 5th Embodiment. (A), (b) is a figure explaining the experiment example in 5th Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Printer, 2 ... Recording paper, 16 ... Recording head, 20 ... Platen, 21 ... Ink drop absorber, 23 ... Piezoelectric vibrator, 30 ... Nozzle plate, 45 ... Paper width sensor, 55 ... Control part, 58 ... Drive signal Generating circuit, 60 ... shift register, 61 ... latch, 62 ... decoder, 63 ... level shifter, 64 ... switch

Claims (10)

A liquid having a series of liquid flow paths including a pressure chamber and a nozzle opening, and pressure generating means for causing a pressure fluctuation in the liquid in the pressure chamber, and ejecting droplets from the nozzle opening by driving the pressure generating means An ejection head;
A drive signal generating means capable of repeatedly generating a plurality of drive signals including discharge pulses for driving the pressure generating means to discharge droplets;
Drive control means for selecting a discharge pulse in the drive signal generated by the drive signal generating means and supplying the selected discharge pulse to the pressure generating means;
A liquid ejecting apparatus comprising:
The drive signal generating means includes
Generating a first drive signal including a first discharge pulse and a second drive signal including a second discharge pulse set so that the flying speed of the discharged droplets is different from the first discharge pulse;
The drive control means selects and supplies the first ejection pulse in the first drive signal to the pressure generating means when ejecting droplets to a theoretical recording area on the recording medium, while the outside of the recording area The liquid ejecting apparatus according to claim 1, wherein the second ejection pulse in the second drive signal is selected and supplied to the pressure generating means when ejecting a droplet to the protruding region.   The liquid ejecting apparatus according to claim 1, wherein the first ejection pulse and the second ejection pulse are set so that the amount of ejected droplets is uniform.   The height of the droplet ejection speed of the second ejection pulse relative to the droplet ejection speed during ejection by the first ejection pulse is determined according to the size of the droplet during ejection. The liquid ejecting apparatus according to claim 1 or 2. Comprising an end detection means for detecting an end in a direction perpendicular to the conveyance direction of the recording medium,
4. The liquid ejecting apparatus according to claim 1, wherein the drive control unit determines the protruding region based on a detection signal from the end detection unit. 5.   4. The method according to claim 1, wherein the drive control unit determines the protrusion area based on data corresponding to the protrusion area in the discharge data developed for discharging a droplet. 5. The liquid ejecting apparatus according to claim 1. A liquid having a series of liquid flow paths including a pressure chamber and a nozzle opening, and pressure generating means for causing a pressure fluctuation in the liquid in the pressure chamber, and ejecting droplets from the nozzle opening by driving the pressure generating means An ejection head;
A drive signal generating means capable of repeatedly generating a plurality of drive signals including discharge pulses for driving the pressure generating means to discharge droplets;
Drive control means for selecting a discharge pulse in the drive signal generated by the drive signal generating means and supplying the selected discharge pulse to the pressure generating means;
A control method of a liquid ejecting apparatus comprising:
Including the first ejection pulse in the first drive signal, and the second drive signal including the second ejection pulse set so that the flying speed of the ejected droplet is different from the first ejection pulse;
The first ejection pulse in the first drive signal is selected and supplied to the pressure generating means when ejecting droplets to the theoretical recording area in the recording medium, while the protruding area set outside the recording area A control method for a liquid ejecting apparatus, wherein the second ejection pulse in the second drive signal is selected and supplied to the pressure generating means when ejecting a droplet to the pressure.   The method of controlling a liquid ejecting apparatus according to claim 6, wherein the first ejection pulse and the second ejection pulse are set so that the amount of ejected droplets is uniform.   The height of the droplet ejection speed of the second ejection pulse relative to the droplet ejection speed during ejection by the first ejection pulse is determined according to the size of the droplet during ejection. The control method of the liquid ejecting apparatus according to claim 6 or 7.   9. The protruding area is determined based on a detection signal from an end detection unit for detecting an end in a direction orthogonal to the conveyance direction of the recording medium. A control method for a liquid ejecting apparatus according to claim 1. 9. The protruding region is determined based on data corresponding to the protruding region in the discharge data developed for discharging a droplet. 10. Control method of liquid ejecting apparatus.

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