JP6048098B2 - Method for driving liquid discharge head and image forming apparatus - Google Patents

Description

  The present invention relates to a liquid ejection head driving method and an image forming apparatus.

  As an image forming apparatus such as a printer, a facsimile, a copying apparatus, a plotter, and a complex machine of these, for example, a liquid discharge recording type image forming apparatus using a recording head composed of a liquid discharge head (droplet discharge head) for discharging droplets An ink jet recording apparatus or the like is known.

  By the way, since the liquid discharge head used in the image forming apparatus performs recording by discharging droplets from the nozzles, if the state in which no droplets are discharged continues, the viscosity of the liquid in the nozzles may evaporate the solvent, etc. Increase by.

  If the droplet discharge operation is performed in a state where the liquid in the nozzle is thickened in this way, the discharge state is disturbed, the discharge state becomes impossible, and the printing quality deteriorates.

  Therefore, a fine driving (also referred to as fine vibration, non-ejection driving, etc.) operation is performed in which the nozzle meniscus is shaken and stirred to such an extent that droplets are not discharged, and the viscosity of the liquid in the nozzle is prevented from increasing.

  Conventionally, for example, a drive signal line for supplying a drive waveform, and a first switch connected between the drive signal line and the drive element and capable of discharging the charge stored in the drive element A circuit, a second switch circuit connected in parallel with the first switch circuit and capable of charging the drive element with electric charge, and the first and second switch circuits with the first and second A switch control circuit for supplying a switching signal, and the first rectifier circuit includes a first switch and a first rectifier circuit connected in series with each other, and the first rectifier circuit includes: A configuration is known in which the direction of current from the drive element to the drive signal line is set to be the forward direction, and avoids inconvenience due to natural discharge when a piezoelectric element is used as the pressure generating means ( Patent Document 1)

JP 2001-113695 A

  As described above, when a piezoelectric element is used as the pressure generating means and a fine drive signal having an intermediate potential as a reference potential is given, a voltage drop due to spontaneous discharge of the piezoelectric element occurs between the fine drive signals. For this reason, when the interval until the next fine drive signal is applied is long, when the next fine drive signal is applied, the droplet is accidentally ejected by returning to the intermediate potential from the potential lowered by the natural discharge. May be.

  For this reason, the provision of a special switch control circuit as disclosed in Patent Document 1 causes a problem that the configuration becomes complicated and the cost increases.

  The present invention has been made in view of the above problems, and an object thereof is to prevent erroneous ejection with a simple configuration without providing a special switch control circuit.

In order to solve the above problems, a method for driving a liquid ejection head according to claim 1 of the present invention includes:
A driving method for driving a liquid discharge head having a nozzle for discharging a droplet and a pressure generating means for generating a pressure for discharging the droplet,
Give a fine driving waveform to the pressure generating means, and perform a fine driving operation to vibrate the meniscus of the nozzle without discharging droplets from the nozzle,
The fine drive waveform is
A waveform element that rises from a potential lower than the falling potential of the fine drive signal to the intermediate potential before and after a fine drive signal that rises to at least the intermediate potential after falling from the intermediate potential, and from the intermediate potential to the fine drive signal A waveform element that falls to a potential lower than the falling potential of
The waveform element that rises to the intermediate potential is a waveform element that does not discharge the droplet from the nozzle.

  According to the present invention, erroneous ejection can be prevented with a simple configuration without providing a special switch control circuit.

1 is an external perspective view illustrating an example of an image forming apparatus according to the present invention. 2 is a schematic side view of the apparatus. FIG. 2 is an explanatory plan view of a main part of an image forming unit of the apparatus. FIG. It is block explanatory drawing with which the outline | summary of the control part of the apparatus is provided. FIG. 6 is an explanatory cross-sectional view along a direction orthogonal to a nozzle arrangement direction of an example of a liquid discharge head. It is sectional explanatory drawing of the direction along the nozzle arrangement direction of the head. It is a block explanatory drawing with which it demonstrates to an example of a head drive control part. It is explanatory drawing with which it uses for description of an example of the fine drive waveform in this embodiment. It is explanatory drawing with which it uses for description of the fine drive waveform of a comparative example.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. An example of an image forming apparatus according to the present invention will be described with reference to FIGS. FIG. 1 is a perspective explanatory view of the image forming apparatus, FIG. 2 is a schematic side view of the image forming apparatus, and FIG.

  This image forming apparatus is a serial type image forming apparatus, and includes an apparatus main body 101 and a paper feeding device 102 disposed below the apparatus main body 101. The paper feeder 102 is separate from the apparatus main body 101 and is disposed below the apparatus main body 101. However, FIG.

  Inside the apparatus main body 101, an image forming unit (printing mechanism unit) 103 that forms an image on a roll paper 120 that is a roll-shaped medium fed from the paper feeding device 102 is disposed.

  In the image forming unit 103, a guide rod 1 and a guide stay 2, which are guide members, are spanned between the side plates 51 and 52, and the carriage 5 is moved in the arrow A direction (main scanning direction, It is held so as to be movable in the carriage movement direction). A subsidiary guide receiver 15 is movably engaged with the guide stay 2.

  A main scanning motor 8 as a drive source for reciprocating the carriage 5 is disposed on one side in the main scanning direction. A timing belt 11 is wound around a driving pulley 9 that is rotationally driven by the main scanning motor 8 and a driven pulley 10 disposed on the other side in the main scanning direction. The belt holding portion 16 of the carriage 5 is fixed to the timing belt 11, and the carriage 5 is reciprocated in the main scanning direction by driving the main scanning motor 8.

  The carriage 5 is equipped with a plurality of (here, four) recording heads 6a to 6d (referred to as “recording head 6” when not distinguished), which are integrated with a liquid discharge head and a head tank that supplies liquid to the head. ing.

  Here, the recording head 6a and the recording heads 6b to 6d are arranged with their positions shifted by one head (one nozzle row) in the sub-scanning direction, which is a direction orthogonal to the main scanning direction. The recording head 6 is mounted with a nozzle row composed of a plurality of nozzles that discharge droplets arranged in the sub-scanning direction orthogonal to the main scanning direction, with the droplet discharging direction facing downward.

  Each of the recording heads 6a to 6d has two nozzle rows. Then, the recording heads 6a and 6b discharge black (black (K)) droplets having the same color from any nozzle row. The recording head 6c discharges cyan (C) droplets from one nozzle row, and the other nozzle row is an unused nozzle row. The recording head 6d ejects yellow (Y) droplets from one nozzle row and magenta (M) droplets from the other nozzle row.

  As a result, monochrome images can be formed with a width of two heads in one scan (main scanning) using the recording heads 6a and 6b, and color images are formed using, for example, the recording heads 6b to 6d. be able to. The head configuration is not limited to this, and a plurality of recording heads may be arranged side by side in the main scanning direction.

  Ink of each color is supplied to the head tank of the recording head 6 from an ink cartridge as a main tank that is replaceably mounted on the apparatus main body 101 via a supply tube.

  An encoder sheet 40 is arranged along the moving direction of the carriage 5, and an encoder sensor 41 that reads the encoder sheet 40 is provided on the carriage 5. The encoder sheet 40 and the encoder sensor 41 constitute a linear encoder 42, and the position and speed of the carriage 5 are detected from the output of the linear encoder 42.

  On the other hand, in the recording area of the main scanning area of the carriage 5, the roll paper 120 is fed from the paper feeding device 102, and the direction perpendicular to the main scanning direction of the carriage 5 (sub-scanning direction, paper conveyance direction) is conveyed by the conveying means 21. : In the direction of arrow B).

  The transport unit 21 includes a transport roller 23 that transports a roll paper 120 that is a roll-shaped medium fed from the paper feeder 102, and a pressure roller 24 that is disposed opposite the transport roller 23. A conveyance guide member 25 having a plurality of suction holes and a suction fan 26 as a suction unit that performs suction from the suction holes of the conveyance guide member 25 are provided on the downstream side of the conveyance roller 23.

  As shown in FIG. 2, a cutter 27 serving as a cutting unit for cutting the roll paper 120 on which an image is formed by the recording head 6 at a predetermined length is disposed on the downstream side of the conveying unit 21.

  Further, on one side of the carriage 5 in the main scanning direction, a maintenance / recovery mechanism 80 that performs maintenance / recovery of the recording head 6 is disposed on the side of the conveyance guide member 25.

  The paper feeding device 102 has a roll body 112. The roll body 112 is obtained by winding a sheet 120 (which is referred to as “roll paper” as described above) 120 in a roll shape around a tube 114 which is a core member.

  Here, in this embodiment, as the roll body 112, the end of the roll paper 120 is fixed to the tube 114 by adhesion such as gluing, and the end of the roll paper 120 is not fixed to the tube 114 by gluing or the like. Any of these can be installed.

  On the apparatus main body 101 side, a guide member 130 that guides the roll body 112 of the paper feeding apparatus 102 and a pair of conveying rollers 131 that curves and feeds the roll paper 120 are disposed.

  By rotating the conveyance roller pair 131, the roll paper 120 fed out from the roll body 112 is conveyed in a stretched state between the conveyance roller pair 131 and the roll body 112. Then, the roll paper 120 is fed between the conveyance roller 23 and the pressure roller 24 of the conveyance unit 21 through the conveyance roller pair 131.

  In the image forming apparatus configured as described above, the carriage 5 is moved in the main scanning direction, and the roll paper 120 fed from the paper feeding device 102 is intermittently fed by the conveying means 21. Then, the recording head 6 is driven according to image information (printing information) to discharge droplets, whereby a required image is formed on the roll paper 120. The roll paper 120 on which the image is formed is cut to a predetermined length by the cutter 27, guided to a paper discharge guide member (not shown) disposed on the front side of the apparatus main body 101, and discharged into the bucket for storage. The

  Next, an outline of the control unit of the image forming apparatus will be described with reference to the block explanatory diagram of FIG.

  The control unit 400 includes a CPU 401, an FPGA (Field Programmable Gate Array) 403, a RAM 411, a ROM 412, an NVRAM 413, a motor driver 414, and the like.

  A calculation unit 402 of the CPU 401 communicates with each unit of the FPGA 403.

  In the FPGA 403, a CPU control unit 404 that communicates with the CPU 401, a memory control unit 405 for accessing a memory such as the ROM 412 and the RAM 411, an I2C control unit 406 that communicates with the NVRAM 413, and a drive control of the recording head 6 are performed. A head control unit 409 and the like are configured.

  In addition, the FPGA 403 includes a sensor processing unit 407 that processes sensor signals such as a temperature / humidity sensor, which is a means for detecting the ambient temperature and ambient humidity of the apparatus, and the encoder sensor 416. The sensor processing unit 407 includes means for generating the position signal and speed signal of the carriage 5 from the output signal of the linear encoder 42 and means for generating the position signal and speed signal of the transport roller 23 from the output signal of the rotary encoder of the transport means 21. Also serves as.

  In addition, a motor control unit 408 that drives and controls the motors 417 of the respective units including the main scanning motor 8 is configured.

  The encoder sensor 416 includes the encoder sensor 41 of the linear encoder 42 that detects the position and speed of the carriage 5 described above, an encoder sensor that constitutes a rotary encoder (not shown) that detects the rotation amount of the transport roller 23, and the like.

  In addition to the main scanning motor 8 described above, the motor 417 includes a sub-scanning motor that rotationally drives the transport roller 23, a paper feed motor that rotationally drives the transport roller pair 131, and the like. For example, a DC motor or a stepping motor can be used as the motor.

  Next, an example of the liquid discharge head constituting the recording head 6 will be described with reference to FIGS. FIG. 5 is a cross-sectional explanatory view along a direction orthogonal to the nozzle arrangement direction of the head, and FIG. 6 is a cross-sectional explanatory view in a direction along the nozzle arrangement direction of the head.

  In the liquid discharge head, a flow path plate 1101, a vibration plate member 1102 bonded to the lower surface of the flow path plate 1101, and a nozzle plate 1103 bonded to the upper surface of the flow path plate 1101 are bonded and stacked.

  Thus, an ink supply port 1109 leading to a common liquid chamber 1108 for supplying ink through a fluid resistance portion (supply path) 1107 to a pressure generating chamber 1106 to which a nozzle 1104 for discharging droplets communicates is formed. Each pressure generating chamber 1106 is separated by a partition wall 1106a.

  Further, two (as shown in FIG. 5, only one row) are stacked as electromechanical conversion elements which are pressure generating means (actuator means) for pressurizing ink in the pressure generating chamber 1106 by deforming the diaphragm member 1102. A type piezoelectric member 1121 is included. The piezoelectric member 1121 is bonded and fixed to the base member 1122.

  The piezoelectric member 1121 is formed with a plurality of columnar piezoelectric elements 1121A and 1121B by forming grooves by slit processing that is not divided. In this example, the piezoelectric column 1121A is a driving piezoelectric column that applies a driving waveform, and the piezoelectric column 1121B is a non-driving piezoelectric column that does not apply a driving waveform. Further, an FPC cable 1126 equipped with a drive circuit (drive IC) (not shown) is connected to the drive piezoelectric column 1121A of the piezoelectric member 1121.

  The peripheral edge of the diaphragm member 1102 is joined to the frame member 1130. The frame member 1130 includes a penetrating portion that houses an actuator unit including a piezoelectric member 1121 and a base member 1122, a concave portion that becomes a common liquid chamber 1108, and a liquid for supplying ink to the common liquid chamber 1108 from the outside. An ink supply hole 1132 which is a supply port is formed.

  Here, the channel plate 1101 is formed by, for example, anisotropically etching a single crystal silicon substrate having a crystal plane orientation (110) with an alkaline etching solution such as an aqueous potassium hydroxide solution (KOH), thereby generating a passage 1105 and pressure generation. A recess or a hole to be the chamber 1106 is formed. However, the present invention is not limited to this, and other stainless steel substrates and photosensitive resins can also be used.

  The diaphragm member 1102 is formed from a nickel metal plate, and is manufactured by, for example, an electroforming method (electroforming method). In addition, a metal plate or a joining member between a metal and a resin plate is used. You can also. Piezoelectric columns 1121A and 1121B of the piezoelectric member 1121 are adhesively bonded to the diaphragm member 1102, and further the frame member 1130 is adhesively bonded.

  The nozzle plate 1103 forms a nozzle 1104 having a diameter of 10 to 30 μm corresponding to each pressure generation chamber 1106 and is bonded to the flow path plate 1101 with an adhesive. This nozzle plate 1103 is formed by forming a water repellent layer on the outermost surface of a nozzle forming member made of a metal member via a required layer.

  The piezoelectric member 1121 is a stacked piezoelectric element (here, PZT) in which piezoelectric materials 1151 and internal electrodes 1152 are alternately stacked. An individual electrode 1153 and a common electrode 1154 are connected to each internal electrode 1152 drawn to alternately different end faces of the piezoelectric member 1121.

  In this embodiment, the ink in the pressure generation chamber 1106 is pressurized using displacement in the d33 direction as the piezoelectric direction of the piezoelectric member 1121, but the present invention is not limited to this. For example, the ink in the pressure generation chamber 1106 may be pressurized using a displacement in the d31 direction as the piezoelectric direction of the piezoelectric member 1121.

  In the liquid ejection head configured as described above, for example, the driving piezoelectric column 1121A contracts by lowering the voltage applied to the driving piezoelectric column 1121A from the reference potential Ve, which is an intermediate potential, and the diaphragm member 1102 descends to generate pressure. The volume of the chamber 1106 expands. As a result, ink flows into the pressure generation chamber 1106. Thereafter, the voltage applied to the driving piezoelectric column 1121A is increased to extend the driving piezoelectric column 1121A in the stacking direction, and the diaphragm member 1102 is deformed in the nozzle 1104 direction to contract the volume of the pressure generating chamber 1106. As a result, the ink in the pressure generation chamber 1106 is pressurized, and ink droplets are ejected (jetted) from the nozzle 1104.

  Then, by returning the voltage applied to the drive piezoelectric column 1121A to the reference potential, the diaphragm member 1102 is restored to the initial position, and the pressure generation chamber 1106 expands to generate negative pressure. At this time, the common liquid chamber 1108 From this, ink is filled into the pressure generation chamber 1106. Therefore, after the vibration of the meniscus surface of the nozzle 1104 is attenuated and stabilized, the operation proceeds to the next droplet discharge operation.

  Next, an example of the head drive control unit will be described with reference to the block diagram of FIG.

  The head drive control unit includes the above-described head control unit 409 and a head driver (driver IC) 509 mounted on the carriage 5 side.

  The head controller 409 generates a drive waveform (common drive waveform) Vcom composed of a plurality of pulses (drive signals) within a predetermined drive cycle and outputs the drive waveform 701, and 2 bits corresponding to the print image Data transfer unit 702 for outputting image data (gradation signals 0 and 1), a clock signal, a latch signal (LAT), and droplet control signals M0 to M3.

  The droplet control signal is a 2-bit signal that instructs each droplet to open and close an analog switch 715 that is a switch unit of the head driver 509 described later. This droplet control signal makes a state transition to the H level (ON) at a pulse or waveform element to be selected in accordance with the drive cycle of the common drive waveform Vcom, and makes a state transition to the L level (OFF) when not selected.

  The head driver 509 receives a transfer clock (shift clock) from the data transfer unit 702 and serial image data (gradation data: 2 bits / 1 channel (1 nozzle)), and register values of the shift register 711. The latch circuit 712 for latching the signal with the latch signal, the decoder 713 for decoding the gradation data and the droplet control signals M0 to M3 and outputting the result, and the logic level voltage signal of the decoder 713 can operate the analog switch 715. A level shifter 714 that performs level conversion to a level and an analog switch 715 that is turned on / off (opened / closed) by the output of the decoder 713 provided through the level shifter 714 are provided.

  The analog switch 715 is connected to a selection electrode (individual electrode) 1153 of each drive piezoelectric column 1121A, and the common drive waveform Vcom from the drive waveform generation unit 701 is input thereto. Accordingly, the analog switch 715 is turned on in accordance with the result of decoding the serially transferred image data (gradation data) and the droplet control signals M0 to M3 by the decoder 713, so that the required pulses constituting the common drive waveform Vcom are generated. (Or a waveform element) is passed (selected) and applied to the driving piezoelectric column 1121A.

  Here, when performing the fine drive operation, the head controller 409 generates a fine drive waveform by the drive waveform generator 701 and outputs this as a common drive waveform Vcom.

  The drive waveform generation unit 701 reads drive waveform data (including fine drive waveform data) stored and held in advance in the ROM 412 or the ROM in the head control unit 409, performs D / A conversion, and performs necessary amplification. And output as a common drive waveform Vcom.

  Next, an example of the fine drive waveform in the present embodiment will be described with reference to FIG.

  The fine drive waveform falls between the fine drive signal P1 that falls from the intermediate potential and then rises to at least the intermediate potential, and the potential lower than the fall potential of the fine drive signal P1 arranged before and after the fine drive signal P1. The waveform includes a waveform element a rising to the potential and a waveform element b falling from the intermediate potential to a potential lower than the falling potential of the fine drive signal P1.

  That is, for each fine drive signal P1, between the fine drive signal P1 and the fine drive signal P1, the waveform element b falls from the intermediate potential to a potential lower than the falling potential of the fine drive signal P1, and the waveform element a Thus, the waveform rises from a potential lower than the falling potential of the fine drive signal P1 to an intermediate potential.

  Note that the intermediate potential of the fine driving waveform may be the same as or different from the intermediate potential of the driving waveform for printing (the reference potential Ve described above).

  Here, the fine drive signal P1 is a signal (non-ejection drive waveform) that vibrates the meniscus of the nozzle without ejecting droplets from the nozzle. The fine drive signal P1 has a waveform that rises after a required hold time (hold time) after falling from the intermediate potential.

  In addition, the waveform element a that rises from a potential lower than the falling potential of the fine drive signal P1 to the intermediate potential is a waveform element that does not discharge a droplet from the nozzle.

  Here, the waveform element a is a waveform element that rises from the ground level (GND) to the intermediate potential, and the waveform element b is a waveform element that falls from the intermediate potential to the ground level. Here, the ground level (GND) is the ground level (for example, 2.3 V) on the drive waveform generation unit (the circuit that generates the fine drive waveform), but may be 0 V.

  In other words, when the fine drive waveform is composed of only the fine drive signal P1 that rises from the intermediate potential and then rises to at least the intermediate potential, as shown in FIG. 9, after adding the fine drive signal P1, Until the drive signal P1 is applied, a potential drop (ΔV) occurs due to spontaneous discharge of the piezoelectric element. For this reason, when the next fine driving signal P1 is applied, the potential returns to the intermediate potential, so that the piezoelectric element is driven and a droplet may be erroneously ejected.

  In particular, when performing printing in the low frequency range, there is a possibility that the waiting time between printing may be long, and if there is another loop in which current flows due to an abnormality in the piezoelectric element, as a result The effect of potential drop due to spontaneous discharge of the piezoelectric element is increased.

  Therefore, in the present embodiment, by inserting the waveform elements b and a for reducing the potential from the intermediate potential to 0 V and then returning to the intermediate potential between the fine drive signals P1 and P1, the potential drop due to the natural discharge of the piezoelectric element is reduced. It suppresses and prevents erroneous ejection.

  In this case, since a fine drive waveform can be used, a switch control circuit is not required as before, and erroneous discharge can be prevented with a simple configuration.

  The fine driving operation using such a fine driving waveform is an operation of detecting the leading edge and the width of the roll paper 120 by moving the carriage 5 and using a paper sensor (not shown) mounted on the carriage 5. It is preferably performed during (roll forming).

  At the time of roll forming, the carriage 5 scans the roll paper 120 as a recording medium, but the moving speed of the carriage 5 is slower than the moving speed at the time of normal printing in order to perform accurate detection. . On the other hand, the drive waveform generation unit 701 generates and outputs a fine drive waveform based on the position signal from the encoder sensor 42 according to the moving speed of the carriage 5.

  Therefore, particularly in an apparatus that uses a wide recording medium such as the roll paper 120, it takes time to scan. Therefore, in order to prevent the nozzles of the recording head 6 in the decap state from being dried, fine scanning during scanning is performed. Driving is required.

  At this time, since the fine drive cycle becomes long, erroneous ejection is likely to occur due to a potential drop due to natural discharge of the piezoelectric element between the fine drive signal and the fine drive signal as described above.

  Therefore, by using the fine drive waveform in the above-described embodiment, erroneous ejection during roll forming can be reliably prevented.

  Note that the fine driving operation using the fine driving signal of the present embodiment is not limited to roll forming. For example, from the start of carriage movement during printing operation to the start of printing (previous fine print area non-printing), during carriage movement without printing (fine carriage drive at previous carriage return), from the end of printing during printing operation Until the carriage stops moving, during carriage movement for pre-printing empty discharge, from paper edge detection to first scan, during paper cutting, during foreign matter check, during recording head up / down, moving to the carriage home position During the calibration of the sensor, it can also be performed between driving waveforms (printing waveforms) in the acceleration / deceleration area.

  That is, when the fine drive waveform is generated and output following the carriage movement speed, if the carriage speed is low, the period for giving the fine drive signal becomes long. Even in this case, by using the fine drive waveform in the present embodiment, it is possible to reduce the influence of the intermediate potential drop regardless of the carriage moving speed, and to prevent erroneous ejection in any frequency region. it can.

  In the present application, “paper” is not limited to paper, but includes OHP, cloth, glass, a substrate, and the like, and means that ink droplets, other liquids, and the like can adhere to the recording medium, recording medium, and recording medium. This includes media, recording paper, and recording paper. In addition, image formation, recording, printing, printing, and printing are all synonymous.

  The “image forming apparatus” means an apparatus that forms an image by discharging a liquid onto a medium such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics or the like. In addition, “image formation” not only applies an image having a meaning such as a character or a figure to a medium but also applies an image having no meaning such as a pattern to the medium (simply applying a droplet to the medium). It also means to land on.

  The “ink” is not limited to an ink unless otherwise specified, but includes any liquid that can form an image, such as a recording liquid, a fixing processing liquid, or a liquid. Used generically, for example, includes DNA samples, resists, pattern materials, resins, and the like.

  In addition, the “image” is not limited to a planar image, and includes an image given to a three-dimensionally formed image and an image formed by three-dimensionally modeling a solid itself.

  In the above-described embodiment, the present invention is applied to an image forming apparatus that uses roll paper. However, the present invention can be similarly applied to an image forming apparatus that uses sheets.

5 Carriage 6 Recording head (Liquid ejection head)
8 Main scanning motor (drive source)
DESCRIPTION OF SYMBOLS 21 Conveyance means 101 Apparatus main body 102 Paper feeding apparatus 112 Roll body 120 Roll paper (sheet, roll-shaped medium)
400 control unit 409 head control unit 509 head driver

Claims (6)

A driving method for driving a liquid discharge head having a nozzle for discharging a droplet and a pressure generating means for generating a pressure for discharging the droplet,
Give a fine driving waveform to the pressure generating means, and perform a fine driving operation to vibrate the meniscus of the nozzle without discharging droplets from the nozzle,
The fine drive waveform is
A waveform element that rises from a potential lower than the falling potential of the fine drive signal to the intermediate potential before and after the fine drive signal that rises to at least the intermediate potential after falling from the intermediate potential, and from the intermediate potential to the fine drive signal A waveform element that falls to a potential lower than the falling potential of
The method of driving a liquid ejection head, wherein the waveform element rising to the intermediate potential is a waveform element that does not eject the droplet from the nozzle.   2. The method of driving a liquid ejection head according to claim 1, wherein the potential lower than the falling potential of the fine drive signal is a ground level on a circuit that generates the fine drive waveform.   The fine drive operation is performed when the liquid discharge head is mounted and a carriage is moved to detect at least one of the leading end and the width of a recording medium on which an image is formed by the liquid discharge head. The method of driving a liquid ejection head according to claim 1 or 2. A liquid ejection head having a nozzle for ejecting liquid droplets, and pressure generating means for generating pressure for ejecting the liquid droplets;
A head drive control means for driving and controlling the liquid discharge head,
The head drive control means includes
Give a fine driving waveform to the pressure generating means, and perform a fine driving operation to vibrate the meniscus of the nozzle without discharging droplets from the nozzle,
The fine drive waveform is
A waveform element that rises from a potential lower than the falling potential of the fine drive signal to the intermediate potential before and after the fine drive signal that rises to at least the intermediate potential after falling from the intermediate potential, and from the intermediate potential to the fine drive signal A waveform element that falls to a potential lower than the falling potential of
The image forming apparatus according to claim 1, wherein the waveform element that rises to the intermediate potential is a waveform element that does not discharge the droplet from the nozzle. 5. The image forming apparatus according to claim 4 , wherein a potential lower than a falling potential of the fine drive signal is a ground level on a circuit that generates the fine drive waveform.   The fine drive operation is performed when the liquid discharge head is mounted and a carriage is moved to detect at least one of the leading end and the width of a recording medium on which an image is formed by the liquid discharge head. The image forming apparatus according to claim 4 or 5.

Images