JP2006231779A - Liquid discharging head, and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid discharging head unit for which the cable connecting constitution is simplified, and of which the miniaturization and the cost reduction can be attained, and to provide an image forming device loaded with the liquid discharging head unit. <P>SOLUTION: Piezoelectric elements 12 and 12 for each row which are arranged on a supporting board 13 are respectively connected with flexible boards 18A and 18B. On respective flexible boards 18A and 18B, driving ICs (driver ICs) 19 and 19 for selectively applying a driving waveform to respective piezoelectric elements 12 are mounted. One flexible board 20 for relaying is connected with the two flexible boards 18A and 18B, and the driving ICs 19 and a control circuit board on the device main body side are connected through the flexible board 20 for relaying. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a liquid discharge head and an image forming apparatus.

  As an image forming apparatus such as a printer, a facsimile, a copying apparatus, and a multifunction machine of these, for example, an ink jet recording apparatus is known. The ink jet recording apparatus uses a liquid discharge head as a recording head, and is a recording medium such as recording paper (hereinafter referred to as “paper”, but the material is not limited to paper, and the recording medium, transfer paper, transfer material, Recording is also performed by ejecting ink droplets as a recording liquid onto the recording material, etc. (image formation, printing, printing, printing, etc. are also synonymous).

  In such an image forming apparatus, for example, when a liquid discharge head including a laminated piezoelectric element that is an electromechanical conversion element is used as a pressure generating unit, it is also referred to as a plurality of piezoelectric element arrays (hereinafter referred to as “piezoelectric element arrays”). ) Are arranged in two rows in a staggered manner, and a flexible substrate on which a driving IC for driving each piezoelectric element is mounted is connected to each piezoelectric element row, and each flexible substrate is controlled on the apparatus body side. Connected to the control unit (control circuit board).

In addition, as described in Patent Document 1, as a connection structure for connecting a conventional flexible substrate and a flexible flat cable, the surface of each electrode of the flexible flat cable and the flexible substrate is soldered to about 1 to 10 μm. The cover resin of the flexible flat cable is made of a thermoplastic resin and has a softening point lower than the melting point of the solder plating. At the time of connection, the electrodes of the flexible flat cable and the flexible substrate are overlapped to form a base resin for the flexible substrate. Heat and press with a thermocompression tool from the side, melt the solder plating, join the electrodes together, melt the cover resin at the same time, and weld to the flexible substrate so as to cover the periphery of the electrode, so that high quality with a fine pitch It is known that the connection structure can be obtained at low cost. It has been.
JP 2004-055400 A

  As described above, a flexible board on which a driving IC is mounted is connected to a liquid ejection head having a plurality of rows of pressure generating means in one liquid ejection head, and wiring to the circuit board of the apparatus main body is all flexible. When the board is extended and used, the number of heads (or the number of nozzle rows) to be mounted increases, especially with high image quality and high speed. As the number of connections increases, the structure becomes complicated and the size cannot be reduced. In addition, the workability of the assembly deteriorates, and the increase in the number of flexible substrates to be used increases the cost.

  In this case, the cost can be reduced by using a flexible flat cable as described in Patent Document 1, but as described above, a plurality of rows of pressure generating means are provided in one liquid discharge head. In such a case, the number of flexible flat cables to be pulled out does not change, so the problem that the configuration becomes complicated and the size cannot be reduced cannot be solved.

  The present invention has been made in view of the above problems, and provides a liquid discharge head unit capable of simplifying a cable connection configuration, reducing the size and reducing the cost, and an image forming apparatus equipped with the liquid discharge head unit. The purpose is to do.

  In order to solve the above-described problems, in the liquid discharge head according to the present invention, at least two rows of pressure generating means for changing the pressure in the liquid chamber communicating with the nozzle for discharging droplets are arranged, and the pressure generating means in each row And at least two flexible boards connected to each other, each of the flexible boards being mounted with a driving IC for driving pressure generating means, and further comprising one relay flexible board for connecting the two flexible boards did.

  Here, it is preferable that the two flexible substrates are fixed to a frame member constituting the head. Alternatively, it is preferable that the connection portion between the two flexible substrates and the relay flexible substrate is sandwiched and fixed by a frame member constituting the head and a pressing member that presses the connection portion.

  An image forming apparatus according to the present invention includes the liquid ejection head according to the present invention.

  According to the liquid ejection head and the image forming apparatus according to the present invention, since the apparatus includes one relay flexible board that connects at least two flexible boards connected to the pressure generating means in each row, The number of connection cables to the circuit board is reduced, the configuration is simplified, and the size and cost can be reduced.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. A first embodiment of a liquid discharge head according to the present invention will be described with reference to FIGS. 1 is a cross-sectional explanatory view along the longitudinal direction of the liquid chamber of the head, and FIG. 2 is a bottom explanatory view of the head.

  This liquid discharge head has, for example, a flow channel plate 1 formed of a single crystal silicon substrate, a vibration plate 2 bonded to the lower surface of the flow channel plate 1, and a nozzle plate 3 bonded to the upper surface of the flow channel plate 1. As a result, the nozzle 4 for ejecting ink droplets forms a pressurized liquid chamber 6 that communicates via the communication path 5, a fluid resistance portion 7, and a communication portion 9 that communicates with the liquid chamber 6 via the fluid resistance portion 7. The recording liquid (for example, ink) is supplied from a common liquid chamber (not shown) formed in the frame member 17 (described later) to the communication portion 9 via a supply port (not shown) formed in the diaphragm 2.

  A laminated piezoelectric element 12 serving as a plurality of pressure generating means is provided on the outer surface of the diaphragm 2 forming the wall surface of the liquid chamber 6 (on the side opposite to the liquid chamber 6) corresponding to each pressurized liquid chamber 6. The lower end portions of the stacked piezoelectric elements 12 are bonded and fixed to the support substrate 13. Two rows of the piezoelectric elements 12 are arranged on the support substrate 13. The piezoelectric element 12 is formed by alternately stacking piezoelectric material layers and internal electrodes as is well known, and the internal electrodes are alternately drawn out to the end face and connected to electrodes (end face electrodes) formed on the end face. .

  Further, the periphery of the flow path plate 1 and the vibration plate 2 is bonded and bonded to a frame member 17 formed by injection molding with, for example, epoxy resin or polyphenylene sulfite, and the frame member 17 and the support substrate 13 are bonded to a portion (not shown). They are fixed to each other with agents. The frame member 17 is formed with the above-described common liquid chamber and a supply path (communication pipe) (not shown) for supplying recording liquid from the outside to the common liquid chamber. The supply path is further illustrated. Not connected to a recording liquid supply source such as a recording liquid cartridge.

  Further, flexible substrates 18A and 18B are connected to the end face electrodes on one side of the piezoelectric elements 12 and 12 in each row by solder bonding, ACF (anisotropic conductive film) bonding or wire bonding in order to give a drive signal, Drive ICs (driver ICs) 19 and 19 for selectively applying drive waveforms to the piezoelectric elements 12 are mounted on the flexible substrates 18A and 18B.

  A single flexible relay board 20 is connected to the two flexible boards 18A and 18B. Specifically, the electrodes 18a and 18b of the flexible boards 18A and 18B and the electrodes 20a and 20b provided on one end side of one relay flexible board 20 are electrically connected by solder bonding or an anisotropic conductive film. ing. An input terminal 21 for connecting to the control circuit board of the apparatus main body is provided at the other end of the relay flexible board 20. Note that relaying means relaying between the flexible substrate of the liquid discharge head and the control circuit substrate of the apparatus main body.

  With this configuration, the flexible substrate drawn out from the liquid ejection head is the relay flexible substrate 20 only, and the wiring and connection to the control circuit board of the apparatus main body are simplified, thereby reducing the size and cost. Can do. The flexible substrate in the relay flexible substrate is used to include a flexible substrate and a flexible flat cable.

Next, a second embodiment of the liquid ejection head according to the present invention will be described with reference to FIG.
In this embodiment, the flexible boards 18 </ b> A and 18 </ b> B are bonded and fixed to the frame member 17 with an adhesive member 22 such as an adhesive or an adhesive. That is, when a force is applied, for example, when the relay flexible substrate 20 is pulled, the connection portion (joint portion) between the flexible substrates 18A and 18B and the relay flexible substrate 20 may be broken. By fixing to the frame member 17, it is made hard to produce the fracture | rupture in a junction part.

Next, a third embodiment of the liquid ejection head according to the present invention will be described with reference to FIG.
In this embodiment, the joint portions (connection portions) between the flexible substrates 18A and 18B and the relay flexible substrate 20 are sandwiched and fixed by the frame member 17 and a pressing member 23 that presses the connection portions. Even if it does in this way, when the relay flexible board | substrate 20 is pulled and force is applied, it is hard to produce the possibility that the connection part (joint part) of flexible board | substrate 18A, 18B and the relay flexible board | substrate 20 may fracture | rupture. Can do.

  Next, an example of the image forming apparatus according to the present invention provided with the liquid discharge head according to the present invention will be described with reference to FIGS. 5 is an explanatory side view for explaining the overall configuration of the image forming apparatus, and FIG.

  In this image forming apparatus, a carriage 104 is slidably held in a main scanning direction by a guide rod 102 and a stay 103, which are guide members horizontally mounted on left and right side plates 101A and 101B constituting a frame 101, and a main scanning motor. 105 moves and scans in the direction indicated by the arrow (main scanning direction) in FIG. 6 via the timing belt 107 spanned between the driving pulley 106A and the driven pulley 106B.

  The carriage 4 includes, for example, a recording head 11 composed of four droplet ejection heads that eject ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (Bk). The nozzle rows on the nozzle surface 111a on which the ejection ports (nozzles) are formed are arranged in a direction (sub-scanning direction) orthogonal to the main scanning direction, and are mounted with the ink ejection direction facing downward. Although an independent droplet discharge head is used here, a configuration in which one or a plurality of heads having a plurality of nozzle rows that discharge droplets of recording liquid of each color can be used. Further, the number of colors and the arrangement order are not limited to this.

  As an inkjet head constituting the recording head 111, a piezoelectric actuator such as a piezoelectric element, a thermal actuator that uses a phase change due to liquid film boiling using an electrothermal transducer such as a heating resistor, and a metal phase change due to a temperature change. It is possible to use a shape memory alloy actuator to be used, an electrostatic actuator using an electrostatic force, or the like provided as pressure generating means for generating a pressure for discharging a droplet.

  As described above, the drive IC 19 is mounted on the recording head 111 and connected to a control unit (control circuit board) on the apparatus main body side, which will be described later, via the relay flexible board 20.

  Also, the carriage 104 is equipped with a sub tank 115 for each color for supplying ink of each color to the recording head 111. Each color sub-tank 115 is replenished and supplied with each color ink from each color ink cartridge 110 mounted in the cartridge loading unit 109 via each color ink supply tube 116. The cartridge loading unit 109 is provided with a supply pump unit 117 for feeding ink in the ink cartridge 110, and the ink supply tube 116 is attached to the rear plate 101C constituting the frame 101 in the middle of turning. It is held by the locking member 118.

  On the other hand, as a paper feeding unit for feeding the paper 122 stacked on the paper stacking unit (pressure plate) 121 of the paper feeding tray 120, a half-moon roller (feeding) that separates and feeds the paper 122 one by one from the paper stacking unit 121. A separation pad 124 made of a material having a large friction coefficient is provided opposite to the sheet roller 123 and the sheet feeding roller 123, and the separation pad 124 is urged toward the sheet feeding roller 123 side.

  In order to feed the sheet 122 fed from the sheet feeding unit to the lower side of the recording head 111, a guide member 125 for guiding the sheet 122, a counter roller 126, a transport guide member 127, and a tip pressure roller. And a holding belt 128 which is a conveying means for electrostatically attracting the fed paper 122 and conveying it at a position facing the recording head 11.

  The transport belt 131 is an endless belt, is configured to be looped between the transport roller 132 and the tension roller 133 and to circulate in the belt transport direction (sub-scanning direction), and while being circulated, the charging roller It is charged (charged) by 134.

  The transport belt 131 may be a single-layer belt or a multi-layer (two or more layers) belt. In the case of the conveyance belt 131 having a one-layer structure, the entire layer is made of an insulating material because it contacts the paper 132 and the charging row 134. In the case of the multi-layered conveyance belt 131, it is preferable that the side that contacts the paper 122 and the charging roller 134 is formed of an insulating layer, and the side that does not contact the paper 122 and the charging roller 134 is formed of a conductive layer. .

The charging roller 134 is disposed so as to contact an insulating layer (in the case of a multilayered belt) forming the surface layer of the transport belt 131, and to rotate following the rotation of the transport belt 131. It is over. The charging roller 134 is formed of a conductive member having a volume resistivity of 10 ⁶ to 10 ⁹ Ω / □. As will be described later, for example, a 2 kV positive and negative AC bias (high voltage) is applied to the charging roller 134 from an AC bias supply unit (high voltage power supply). The AC bias may be a sine wave or a triangular wave, but a square wave is more preferable.

  In addition, a guide member 135 is disposed on the back side of the conveyance belt 131 so as to correspond to a printing area by the recording head 111. The guide member 135 has a top surface that protrudes toward the recording head 111 with respect to the tangent line of two rollers (the conveyance roller 132 and the tension roller 133) that support the conveyance belt 131, thereby maintaining high-precision flatness of the conveyance belt 131. Like to do.

  The transport belt 131 rotates in the belt transport direction of FIG. 6 when the transport roller 132 is rotationally driven by the sub-scanning motor 136 via the drive belt 137 and the timing roller 138. Although not shown, an encoder wheel having a slit is attached to the shaft of the transport roller 132, and a transmission type photo sensor for detecting the slit of the encoder wheel is provided, and the wheel encoder is configured by the encoder wheel and the photo sensor. It is composed.

  Further, as a paper discharge unit for discharging the paper 122 recorded by the recording head 111 to the paper discharge tray 140, a separation claw 141 for separating the paper 122 from the conveyance belt 131, a paper discharge roller 142, and paper discharge A roller 143.

  In addition, a double-sided unit 151 that is a means for inverting the paper 122 when performing double-sided printing is detachably mounted on the back surface of the apparatus main body. The duplex unit 151 takes in the paper 122 returned by the reverse rotation of the transport belt 131, reverses it, and feeds it again between the counter roller 126 and the transport belt 131.

  Further, a maintenance / recovery mechanism 161 for maintaining and recovering the state of the nozzles of the recording head 111 is disposed in a non-printing area on one side of the carriage 104 in the scanning direction. The maintenance / recovery mechanism 161 includes cap members (hereinafter referred to as “caps”) 162a to 162d (hereinafter referred to as “caps 162” when not distinguished from each other) for capping each nozzle surface 111a of the recording head 111, and nozzles. A wiper blade 163 that is a blade member for wiping the surface 111a, an empty discharge receiver 164 that receives liquid droplets when performing an empty discharge for discharging liquid droplets that do not contribute to recording in order to discharge the thickened recording liquid, and the like It has. Here, the cap 162a is a suction and moisture retention cap, and the other caps 162b to 162d are moisture retention caps.

  In addition, in the non-printing area on the other side of the carriage 104 in the scanning direction, there is an empty space for receiving a liquid droplet when performing an empty discharge for discharging a liquid droplet that does not contribute to recording in order to discharge the recording liquid thickened during recording or the like. An ejection receiver 168 is disposed, and the idle ejection receiver 168 is provided with an opening 169 along the nozzle row direction of the recording head 111 and the like.

  As shown in FIG. 5, an encoder scale 172 having slits is provided along the main scanning direction on the front side of the carriage 104, and a transmission type that detects the slits of the encoder scale 172 on the front side of the carriage 104. An encoder sensor 173 including a photo sensor is provided, and these constitute a linear encoder 174 for detecting the position of the carriage 104 in the main scanning direction (position relative to the home position).

  Further, a paper leading edge detection sensor 175 configured by a reflective photosensor that detects the presence or absence of the paper 122 conveyed by the conveyance belt 131 is provided on the side surface portion of the carriage 104 on the print area side. This paper leading edge detection sensor (paper sensor) 175 is provided at a position where the paper 122 can be detected upstream of the recording position (printing area) by the recording head 111 in the paper transport direction. The sheet sensor 175 is provided on the side positioned on the recording area side (conveying belt 131 side) when the carriage 103 is at the home position (position moved to the right end in FIG. 6).

  Further, a conveyance roller nip portion is formed by the conveyance roller 131 and the counter roller 126, and a sheet sensor 177 for detecting the sheet 122 is disposed at a predetermined position upstream of the conveyance roller nip portion in the sheet conveyance direction. The sheet sensor 177 detects the sheet 122 by displacing the detection lever 177a by the sheet 122 (the position indicated by the broken line in FIG. 5 is the ON position). The paper sensor 177 is for detecting the paper 122 being fed.

Next, an outline of the control unit of the image forming apparatus will be described with reference to the block diagram of FIG.
The control unit 200 includes a CPU 201 that controls the entire apparatus, a ROM 202 that stores programs executed by the CPU 201 and other fixed data, a RAM 203 that temporarily stores image data and the like, and a power source for the apparatus. A rewritable non-volatile memory 204 for holding data in between, an image processing for performing various signal processing and rearrangement on image data, and an ASIC 205 for processing input / output signals for controlling the entire apparatus. ing.

  The control unit 200 generates an I / F 206 for transmitting and receiving data and signals to and from the host side, and a drive waveform for driving the recording head 111, and selects a pressure generating means for the recording head 211. A head control unit 207 that outputs image data to be driven and various data accompanying the image data to the driving IC 19 (head driver 208), a main scanning motor driving unit 210 for driving the main scanning motor 105, and a sub-scanning motor 136 are driven. ON / OFF of a sub-scanning motor driving unit 211 for controlling the rotation, an AC bias supplying unit 212 for supplying an AC bias to the charging roller 134, and a sheet feeding clutch 216 for transmitting the rotation of the sub-scanning motor 136 to the sheet feeding roller 123 Detection pulse from the driver 215, the linear encoder 174, and the wheel encoder 217 Paper sensor 75 comprises the detection signal from the sheet sensor 77, and the like I / O213 to enter other detection signals from various sensors. The control unit 200 is connected to an operation panel 214 for inputting and displaying information necessary for the apparatus.

  Here, the control unit 200 transmits print data generated by a host printer driver such as an information processing apparatus such as a personal computer, an image reading apparatus such as an image scanner, an imaging apparatus such as a digital camera, etc. via a cable or a network. Received at / F206.

  Then, the CPU 201 of the control unit 200 reads and analyzes the print data in the reception buffer included in the I / F 206, performs necessary image processing, data rearrangement processing, and the like in the ASIC 205 and transfers them to the head control unit 207. Then, image data and a driving waveform are output from the head control unit 207 to the driving IC 19 (head driver 108) at a required timing. The drive waveform generation unit of the head control unit 207 includes a D / A converter and an amplifier that perform D / A conversion on drive pulse pattern data stored in the ROM 202 and read by the CPU 201, and includes one drive pulse or a plurality of drive pulses. A drive waveform composed of drive pulses is output to the head driver 208.

  The head driver 208 generates drive pulses constituting a drive waveform provided from the drive waveform generation unit of the head control unit 207 based on image data (dot pattern data) corresponding to one line of the recording head 211 input serially. The recording head 211 is driven by selectively applying to the pressure generating means of the recording head 211. The head driver 208, for example, shifts the level of the shift register that receives a clock signal and serial data that is image data, a latch circuit that latches the register value of the shift register using a latch signal, and the output value of the latch circuit. A level conversion circuit (level shifter) and an analog switch array (switch means) whose on / off is controlled by this level shifter, etc., and the required drive pulse included in the drive waveform by controlling the on / off of the analog switch array Is selectively applied to the pressure generating means of the recording head 211.

  In the image forming apparatus configured as described above, the sheet 122 is separated and fed one by one from the sheet feeding unit, and the sheet 122 fed substantially vertically upward is guided by the guide 125, and includes the conveyance belt 131 and the counter roller 126. The leading end is guided by the conveying guide 127 and pressed against the conveying belt 131 by the leading end pressing roller 129, and the conveying direction is changed by approximately 90 °.

  At this time, a positive output and a negative output are alternately repeated from the AC bias supply unit 212 to the charging roller 134, that is, an alternating voltage is applied, and a charging voltage pattern in which the conveying belt 131 alternates, that is, a rotating direction. In the sub-scanning direction, plus and minus are alternately charged in a band shape with a predetermined width. When the sheet 132 is fed onto the conveyance belt 131 that is alternately charged with plus and minus, the sheet 122 is attracted to the conveyance belt 131 by electrostatic force, and the sheet 122 is conveyed in the sub-scanning direction by the circular movement of the conveyance belt 131. Is done.

  Therefore, by driving the recording head 111 according to the image signal while moving the carriage 104, ink droplets are ejected onto the stopped sheet 122 to record one line, and after conveying the sheet 122 by a predetermined amount, Record the next line. Upon receiving a recording end signal or a signal that the trailing edge of the sheet 122 has reached the recording area, the recording operation is terminated and the sheet 122 is discharged onto the discharge tray 140.

  In the case of double-sided printing, when recording of the front surface (surface to be printed first) is completed, the recording belt 132 is fed into the double-sided paper feeding unit 151 by rotating the transport belt 131 in the reverse direction. The paper 122 is reversed (with the back surface being the printing surface), fed again between the counter roller 126 and the conveyor belt 131, controlled in timing, and conveyed by the conveyor bell 131 as described above. After recording on the back surface, the paper is discharged onto the paper discharge tray 140.

  As described above, in this image forming apparatus, the control unit 200 and the drive IC 19 (head driver 208) for driving the pressure generating unit of the recording head 111 including the liquid discharge head are connected to the flexible substrates 18A and 18B. Since the connection is made via the relay flexible substrate 20, the configuration is simplified.

  In the above embodiment, the printer configuration has been described as the image forming apparatus according to the present invention. However, the present invention is not limited to this, and can be applied to an image forming apparatus such as a printer / fax / copier multifunction machine. Further, the present invention can be applied to an image forming apparatus using a recording liquid or a fixing processing liquid that is a liquid other than ink.

1 is a cross-sectional explanatory diagram illustrating a first embodiment of a liquid ejection head according to the present invention. It is the plane explanatory view which looked at the head of Drawing 1 from the lower side. FIG. 6 is an explanatory cross-sectional view showing a second embodiment of the liquid ejection head according to the present invention. FIG. 6 is a cross-sectional explanatory view illustrating a third embodiment of the liquid ejection head according to the present invention. 1 is an overall configuration diagram illustrating an example of an image forming apparatus according to the present invention. Similarly it is principal part plane explanatory drawing. It is a block diagram which similarly shows the outline | summary of a control part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Flow path plate 2 ... Vibration board 3 ... Nozzle plate 4 ... Nozzle 6 ... Liquid chamber 12 ... Piezoelectric element 17 ... Frame member 18A, 18B ... Flexible substrate 19 ... Drive IC
20 ... Flexible substrate for relay 104 ... Carriage 111 ... Recording head

Claims (4)

  At least two rows of pressure generating means for changing the pressure in the liquid chamber that communicates with the nozzle that discharges droplets are arranged, and each flexible substrate includes at least two flexible substrates connected to the pressure generating means of each row. A liquid discharge head on which a driving IC for driving the pressure generating means is mounted, the liquid discharge head comprising one relay flexible substrate for connecting two flexible substrates.   The liquid discharge head according to claim 1, wherein the two flexible substrates are fixed to a frame member constituting the head.   2. The liquid discharge head according to claim 1, wherein a connection portion between the two flexible substrates and the relay flexible substrate is sandwiched and fixed by a frame member constituting the head and a pressing member that presses the connection portion. A liquid discharge head characterized by the above. 4. An image forming apparatus comprising: a liquid discharge head according to claim 1, wherein the liquid discharge head is mounted to form an image on a recording medium.

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