JP2006187932A - Head data transfer device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the following problem that the number of signal wires is increased even if data transfer for driving a recording head is performed by serial data transfer, or that electromagnetic interference is easily caused by turning a transfer clock into a higher frequency. <P>SOLUTION: Serial data S21-S24, which alternately include two transfer clocks S10 and S20 different in phase and data on each nozzle array of the same head for each channel, are transferred to driver ICs 311-318 corresponding to respective print heads 301-308, mounted on the recording head 11, from a print-head data transfer device 300 via an FPC cable 12, so that the plurality of data can be transferred in one transfer cycle. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a head data transfer apparatus and an image forming apparatus.

  As various image forming apparatuses such as printers, facsimiles, copying machines, plotters, printer / fax / copier multifunction machines, etc., recording heads (printing heads) constituted by droplet discharging heads that discharge recording liquid (for example, ink) droplets are used. ) Is mounted on a carriage, and the carriage is a recording medium (hereinafter referred to as “paper”, but the material is not limited to paper, and is also referred to as recording medium, recording paper, transfer material, etc.). In addition to serial scanning in a direction orthogonal to the conveyance direction, the recording medium is intermittently conveyed according to the recording width, and an image is formed on the recording medium by repeating conveyance and recording (recording, printing, Printing and printing are also used synonymously.) There is a serial type image forming apparatus or a line type image forming apparatus equipped with a line type recording head.

  In an image forming apparatus equipped with such a recording head, actuator means (for example, a piezoelectric element in a piezoelectric head, a heating resistor in a thermal head, and an opposing electrode in an electrostatic head) provided in the recording head are driven. In general, serial data transfer is used as a head data transfer device for transferring data to the driver on the print head side from the control unit side.

The configuration of a head data transfer apparatus that performs such serial transfer will be briefly described with reference to FIGS.
Here, on the carriage 500, four print heads from the first head to the fourth head are provided, and each print head has two nozzle rows A and B in which a plurality of nozzles are arranged in rows. The nozzle rows of the A and B rows of the first to fourth heads are designated as print heads 501 to 508, and actuator means (means for generating pressure for ejecting droplets) corresponding to the eight print heads 501 to 508. The driver ICs 511 to 518 are mounted.

  A print head data transfer device 520 is provided on the control unit side, and the print head data transfer device 520 and driver ICs 511 to 518 on the carriage 500 side are connected via an FPC cable 530.

  Here, as shown in FIG. 15, the print head data transfer device 520 outputs a transfer clock S510 to each of the driver ICs 511 to 518 and serial data S511 for driving the print heads 501 to 508. To S518 are output to the driver ICs 511 to 518, respectively.

  As shown in FIG. 16 (enlarged explanatory diagram of the period T5 in FIG. 15), the driver ICs 511 to 518 receive the serial data S511 to S518 at the rising edge of the transfer clock S510 (the edge to which an arrow is added in the figure). Is sent to the print heads 501 to 508. Further, as shown in FIG. 16, the serial data S511 to S518 include data in the order of each nozzle channel (head 1 / nozzle row A / nozzle ch1, head 1 / nozzle row A / nozzle ch2,...). It will be output.

  Note that “nozzle channel” means each nozzle from the first nozzle to the m-th nozzle when one nozzle row is formed by m nozzles. Further, “head 1” in FIG. 13 means the first head, “nozzle row A” means the nozzle row of the A row, and “nozzle ch1” means the first nozzle channel (the same applies to others).

  In such a serial transfer configuration, when the total number of signal lines on the FPC cable necessary for data transfer is nine and the transfer clock frequency is 8 MHz, the transfer rate for all heads and all nozzles is 64 Mbps. .

Conventionally, in order to efficiently perform such serial transfer, for example, the following image forming apparatus, head driving apparatus, serial data transfer apparatus, and the like are known. That is, as described in Patent Document 1, in order to shorten the transfer time of image data without increasing the transfer frequency of image data, a plurality of recording elements are provided, and according to data input serially according to a clock signal. A recording head that performs recording by driving each recording element, and when a plurality of data is input in each cycle of the clock signal, generates a timing signal having a period of a multiple of the signal from the clock signal. There is provided a timing signal generating means, a shift register for inputting each of a plurality of data inputted in each cycle in accordance with the timing signal, and a data output means for outputting data in parallel from the shift register.
JP 2002-066732 A

As described in Patent Document 2, a plurality of recording elements and a drive circuit for driving the recording elements are the same in order to cope with high-speed data transfer even when the power supply voltage is lowered. A recording head provided on an element substrate, wherein a drive circuit includes a double clock generation circuit that generates a second clock signal having a frequency twice that of the input first clock signal, and an input serial Some include a shift register that sequentially stores data in synchronization with one of the edges of the second clock signal.
JP 2002-370361 A

Similarly, as described in Patent Document 3, a plurality of recording elements and a driving circuit for driving the recording elements are provided in order to cope with a high data transfer speed even when the power supply voltage is lowered. A recording head provided on the same element substrate, which generates a first signal having a frequency twice that of the input clock signal and a second signal obtained by delaying the first signal. A generation circuit, a selection circuit that selects one of the first and second signals according to the state of the serially input data signal, and data that is input as a data signal according to the signal selected by the selection circuit And a shift register for sequentially storing the.
JP 2002-370361 A

As described in Patent Document 4, in order to reduce the number of signal lines by sharing signal lines for transmitting signals for driving a plurality of print heads, serial data that is provided for each print head and is print data A drive circuit in which a serial data signal line that transmits a signal and a transfer clock signal line that transmits a transfer clock signal of the serial data signal are wired, and each of the drive circuits shares a serial data signal line, Some serial data signals on serial data signal lines are transmitted to respective drive circuits based on transfer clock signals on transfer clock signal lines.
JP 2003-145726 A

As described in Patent Document 5, in order to simplify the structure of the recording head unit and reduce the number of signal lines to the recording head, a plurality of recording element groups corresponding to a plurality of colors and corresponding to each recording color Including a recording unit equipped with a recording head, storing and holding means for storing and holding recording data smaller in number than all the recording elements, transfer means for serially transferring data to be recorded to the storing and holding means, and storing and holding There is a drive unit that divides the data stored and held in the unit into a plurality of blocks, selects data in each divided block in a time division manner, and drives the drive corresponding to the recording element group.
Japanese Patent No. 3142698

As described in Japanese Patent Laid-Open No. 2004-260, data transfer is performed serially so that one signal line is used, and dummy data is not required to be transferred to reduce data transfer time. Serial input shift register means for receiving 1-bit serial print data having a maximum n-bit gradation per pixel, determining a drive waveform for driving the head according to the received print data, and shifting the received 1-bit serial print data And a means for changing the shift path of the shift register means according to the number of bits m of the gradation to be received (where 1 ≦ m ≦ n).
Japanese Patent Laid-Open No. 11-263042

As described in Patent Document 7, in order to prevent the data transfer speed of the integrated circuit for driving the thermal head from being lowered and to reduce the bonding pads and current consumption, the heating resistor is energized in accordance with the data signal. An integrated circuit for driving a thermal head to be controlled, wherein shift registers for sequentially transferring and storing serially supplied data signals are arranged in at least two stages in series, and the stored data signals are read in a batch And a data signal input terminal and output terminal for the preceding shift register, a data signal input terminal and output terminal for the subsequent shift register, and an output terminal and subsequent stage of the preceding shift register. Switch means interposed between the input terminal of the shift register and the switch means. There is a connection with the separation of the shift register arranged in series those to be selected.
Japanese Patent No. 3169932

As described in Patent Document 8, in order to reduce the number of signal lines connecting a movable object such as a carriage and a fixed object such as a control unit as much as possible, and to reduce the size and cost of the apparatus. In a printer device that scans a carriage mounted with a plurality of ink jet heads and ink cartridges and prints on a recording sheet, various information of the ink jet heads and ink cartridges mounted on the movable carriage are fixed to the main body by serial data transfer Some of them are transmitted to the control unit.
JP 2001-191511 A

  However, in any case, in the conventional serial data transfer configuration, the number of heads or nozzle rows increases because serial data is transferred to each head or each nozzle row by one transfer clock signal. As a result, the number of data signal lines also increases, which makes it difficult to reduce the size and cost of the data transfer device and the head.

  Also, in order to increase the data transfer rate in order to meet the demand for higher printing speeds, the transfer clock frequency must be increased, resulting in lower signal stability and electromagnetic interference (EMI) due to higher transfer clock frequencies. There is a problem in that there is a risk of an increase in environmental load.

  The present invention has been made in view of the above-described problems, and provides a head data transfer device that suppresses an increase in the number of signal lines with a simple configuration or achieves a high transfer rate, and an image forming apparatus including the head data transfer device. For the purpose.

  In order to solve the above problems, a head data transfer device according to the present invention is a head data transfer device that transfers data for driving the print head to a print head composed of a plurality of nozzle rows or heads. The apparatus includes a means for transferring a plurality of data for driving the recording head during one transfer cycle by using a plurality of transfer clocks having different phases.

  Here, the plurality of transfer clocks are preferably two transfer clocks having inverted phases. Further, the plurality of data may be data for a plurality of different nozzle rows provided in the same head, or the plurality of data may be data for different channels of the same nozzle row provided in the same head. preferable.

  An image forming apparatus according to the present invention includes any one of the data transfer apparatuses according to the present invention.

  The data transfer apparatus and image forming apparatus according to the present invention include means for transferring a plurality of data for driving the recording head during one transfer cycle using a plurality of transfer clocks having different phases. Therefore, the increase in the number of signal lines can be suppressed to reduce the size and cost of the apparatus, or the transfer rate can be increased with the transfer clock having the same frequency.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. First, an example of a mechanism part of the image forming apparatus according to the present invention will be described with reference to FIGS. FIG. 1 is an explanatory side view for explaining the overall structure of the mechanism section, and FIG. 2 is a plan explanatory view of the mechanism section.

  In this image forming apparatus, a carriage 4 is slidably held in a main scanning direction by a guide rod 2 and a stay 3 which are guide members horizontally mounted on left and right side plates 1A and 1B constituting a frame 1, and a main scanning motor. 5 is moved and scanned in the direction indicated by the arrow (main scanning direction) in FIG. 2 via the timing belt 7 spanned between the driving pulley 6A and the driven pulley 6B.

  The carriage 4 includes, for example, four droplet ejection heads 11k, 11c, 11m, and 11y that eject ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (Bk). The recording head 11 is mounted with the nozzle row of the nozzle surface 11a on which a plurality of ink discharge ports (nozzles) are formed arranged in a direction (sub-scanning direction) orthogonal to the main scanning direction, and the ink discharging direction is directed 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.

  Here, as described above, the recording head 11 is composed of four separate heads 11k, 11c, 11m, and 11y that discharge droplets of the respective colors, and the heads 11k, 11c, 11m, and 11y are shown in FIG. As described above, the nozzle array is formed by arranging two nozzles n for discharging droplets side by side (each nozzle array is referred to as nozzle arrays NA and NB). Not limited to this, as shown in FIG. 4, two nozzle rows 11 kA, 11 kB, 11 cA, 11 cB, 11 mA, 11 mB, 11 yA, and 11 yB that discharge droplets of each color are arranged in one recording head 11. It can also be constituted by a head having one or a plurality of nozzle rows that eject black ink and a head having one or a plurality of nozzle rows for each color that ejects color ink.

  As an inkjet head constituting the recording head 11, a piezoelectric actuator such as a piezoelectric element, a thermal actuator that uses a phase change caused by film boiling of a liquid using an electrothermal transducer such as a heating resistor, and a metal phase change caused by 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.

  A driver IC is mounted on the recording head 11 and connected to a control unit (not shown) via a harness (flexible print cable: FPC cable) 12.

  In addition, the carriage 4 is equipped with a sub tank 15 for each color for supplying ink of each color to the recording head 11. Each color sub-tank 15 is supplementarily supplied with ink of each color from the ink cartridge 10 of each color mounted in the cartridge loading unit 9 via the ink supply tube 16 of each color. The cartridge loading 9 is provided with a supply pump unit 17 for feeding ink in the ink cartridge 10, and the ink supply tube 16 is engaged with the rear plate 1C constituting the frame 1 in the middle of turning. It is held by a stop member 18.

  On the other hand, as a paper feed unit for feeding the paper 22 stacked on the paper stacking unit (pressure plate) 21 of the paper feed tray 20, a half-moon roller (feed) that separates and feeds the paper 22 one by one from the paper stacking unit 21. A separation pad 24 made of a material having a large friction coefficient is provided opposite to the sheet roller 23 and the sheet feeding roller 23, and the separation pad 24 is biased toward the sheet feeding roller 23 side.

  In order to feed the paper 22 fed from the paper feeding unit to the lower side of the recording head 11, a guide member 25 for guiding the paper 22, a counter roller 26, a conveyance guide member 27, and a tip pressure roller. And a holding belt 28 as a conveying means for electrostatically attracting the fed paper 22 and conveying it at a position facing the recording head 11.

  The conveyance belt 31 is an endless belt, is configured to wrap around the conveyance roller 32 and the tension roller 33 and circulate in the belt conveyance direction (sub-scanning direction). 34 is charged (charged).

  The transport belt 31 may be a single-layer belt or a multi-layer (two or more layers) belt. In the case of the conveyance belt 31 having a one-layer structure, the entire layer is formed of an insulating material because it contacts the paper 32 and the charging row 34. In the case of the transport belt 31 having a multi-layer structure, the side that contacts the paper 22 and the charging roller 34 is preferably formed of an insulating layer, and the side that does not contact the paper 22 and the charging roller 34 is preferably formed of a conductive layer. .

As an insulating material for forming the transport belt 31 having a single layer structure and an insulating material for forming the insulating layer of the transport belt 31 having a multi-layer structure, for example, a conductive material such as PET, PEI, PVDF, PC, ETFE, or PTFE is used. It is preferable that the material does not contain a control material, and the volume resistivity is 10 ¹² Ωcm or more, preferably 10 ¹⁵ Ωcm. Further, as a material for forming the conductive layer of the transport belt 31 having a multi-layer structure, it is preferable that carbon is contained in the resin or elastomer so that the volume resistivity is 10 ⁵ to 10 ⁷ Ωcm.

The charging roller 34 is disposed so as to come into contact with an insulating layer (in the case of a multilayer belt) that forms the surface layer of the transport belt 31 and to rotate following the rotation of the transport belt 31. It is over. The charging roller 34 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 / negative AC bias (high voltage) is applied to the charging roller 34 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 35 is disposed on the back side of the conveyance belt 31 so as to correspond to a printing area by the recording head 11. The guide member 35 has an upper surface that protrudes toward the recording head 11 from the tangent line of the two rollers (the conveyance roller 32 and the tension roller 33) that support the conveyance belt 31, thereby maintaining high-precision flatness of the conveyance belt 31. Like to do.

  The transport belt 31 rotates in the belt transport direction of FIG. 2 when the transport roller 32 is rotationally driven by the sub-scanning motor 36 via the drive belt 37 and the timing roller 38. Although not shown, an encoder wheel having a slit is attached to the shaft of the conveying roller 32, and a transmission type photosensor for detecting the slit of the encoder wheel is provided, and the wheel encoder is configured by the encoder wheel and the photosensor. It is composed.

  Further, as a paper discharge unit for discharging the paper 22 recorded by the recording head 11 to the paper discharge tray 40, a separation claw 41 for separating the paper 22 from the transport belt 31, a paper discharge roller 42, and paper discharge The roller 43 is provided.

  A duplex unit 51 is detachably mounted on the back surface of the apparatus body 1. The duplex unit 51 takes in the paper 22 returned by the reverse rotation of the transport belt 31, reverses it, and feeds it again between the counter roller 26 and the transport belt 31. The upper surface of the duplex unit 51 is a manual feed tray 52.

  Further, a maintenance / recovery mechanism 61 for maintaining and recovering the state of the nozzles of the recording head 11 is disposed in a non-printing area on one side in the scanning direction of the carriage 4. The maintenance / recovery mechanism 61 includes cap members (hereinafter referred to as “caps”) 62 a to 62 d (hereinafter referred to as “caps 62” when not distinguished) and nozzles for capping the nozzle surfaces 11 a of the recording head 11. A wiper blade 63 that is a blade member for wiping the surface 11a, an empty discharge receiver 64 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 62a is a suction and moisture retention cap, and the other caps 62b to 62d are moisture retention caps.

  Further, in the non-printing area on the other side of the scanning direction of the carriage 4, 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. A discharge receiver 68 is disposed, and the idle discharge receiver 68 is provided with an opening 69 along the nozzle row direction of the recording head 11.

  Further, as shown in FIG. 1, a density sensor 71 including an infrared sensor (a type of sensor is not limited to the infrared sensor) which is a medium detecting unit for detecting the presence or absence of the paper 22 in the carriage 4. Is provided. The density sensor 71 is provided on the recording area (image forming area) side (conveying belt 31 side) side of the carriage 4 at the home position and upstream of the recording head 11 in the paper conveying direction. .

  Further, an encoder scale 72 having slits is provided on the front side of the carriage 4 along the main scanning direction, and an encoder sensor 73 including a transmission type photosensor for detecting the slits of the encoder scale 72 is provided on the front side of the carriage 4. These components constitute a linear encoder 74 for detecting the position of the carriage 4 in the main scanning direction.

  Next, an example of a droplet discharge head constituting the recording head in this image forming apparatus will be described with reference to FIGS. 5 is a cross-sectional explanatory view along the longitudinal direction of the liquid chamber of the head, and FIG. 6 is a cross-sectional explanatory view of the head along the lateral direction of the liquid chamber (nozzle arrangement direction).

  The droplet discharge head includes a flow channel plate 101 formed by anisotropic etching of a single crystal silicon substrate, a vibration plate 102 formed by nickel electroforming, for example, bonded to the lower surface of the flow channel plate 101, and a flow plate. A nozzle plate 103 bonded to the upper surface of the path plate 101 is bonded and stacked, and a nozzle communication path 105, a liquid chamber 106, and a liquid chamber, which are channels through which the nozzles 104 that discharge liquid droplets (ink droplets) communicate with each other. An ink supply port 109 communicating with a common liquid chamber 108 for supplying ink to 106 is formed.

  In addition, two rows (only one row is shown in FIG. 6) of stacked piezoelectric elements as electromechanical conversion elements that are pressure generating means (actuator means) for pressurizing ink in the liquid chamber 106 by deforming the diaphragm 102. An element 121 and a base substrate 122 to which the piezoelectric element 121 is bonded and fixed are provided. Note that a column portion 123 is provided between the piezoelectric elements 121. This support portion 123 is a portion formed simultaneously with the piezoelectric element 121 by dividing and processing the piezoelectric element member. However, since the drive voltage is not applied, the support portion 123 becomes a simple support.

  Further, an FPC cable 12 equipped with a drive circuit (drive IC) (not shown) is connected to the piezoelectric element 121.

  The peripheral edge of the diaphragm 102 is joined to a frame member 130, and the frame member 130 serves as a through-hole 131 and a common liquid chamber 108 that house an actuator unit composed of the piezoelectric element 121 and the base substrate 122. A recess and an ink supply hole 132 for supplying ink from the outside to the common liquid chamber 108 are formed. The frame member 130 is formed by injection molding with a thermosetting resin such as an epoxy resin or polyphenylene sulfite, for example.

  Here, the flow path plate 101 is formed by, for example, subjecting the single crystal silicon substrate having a crystal plane orientation (110) to anisotropic etching using an alkaline etching solution such as an aqueous potassium hydroxide solution (KOH), so that the nozzle communication path 105, Although a recess or a hole serving as the liquid chamber 106 is formed, the invention is not limited to a single crystal silicon substrate, and other stainless steel substrates, photosensitive resins, and the like can also be used.

  The vibration plate 102 is formed from a nickel metal plate, and is manufactured by, for example, an electroforming method (electroforming method). Alternatively, a metal plate or a joining member between a metal and a resin plate may be used. it can. The piezoelectric element 121 and the support post 123 are bonded to the diaphragm 102 with an adhesive, and the frame member 130 is further bonded with an adhesive.

  The nozzle plate 103 forms a nozzle 104 having a diameter of 10 to 30 μm corresponding to each liquid chamber 106 and is bonded to the flow path plate 101 with an adhesive. The nozzle plate 103 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 surface of the nozzle plate 103 is the nozzle surface 34a described above.

  The piezoelectric element 121 is a stacked piezoelectric element (here, PZT) in which piezoelectric materials 151 and internal electrodes 152 are alternately stacked. An individual electrode 153 and a common electrode 154 are connected to each internal electrode 152 drawn out to different end faces of the piezoelectric element 121 alternately. In this embodiment, the ink in the liquid chamber 106 is pressurized using the displacement in the d33 direction as the piezoelectric direction of the piezoelectric element 121. However, the pressure in the d31 direction is used as the piezoelectric direction of the piezoelectric element 121. The ink in the liquid chamber 106 may be pressurized. Alternatively, a structure in which one row of piezoelectric elements 121 is provided on one substrate 122 may be employed.

  In the droplet discharge head configured as described above, for example, by lowering the voltage applied to the piezoelectric element 121 from the reference potential, the piezoelectric element 121 contracts, and the vibration plate 102 descends to expand the volume of the liquid chamber 106. As a result, the ink flows into the liquid chamber 106, and then the voltage applied to the piezoelectric element 121 is increased to extend the piezoelectric element 121 in the stacking direction, and the diaphragm 102 is deformed in the direction of the nozzle 104 to change the volume of the liquid chamber 106. / By contracting the volume, the recording liquid in the liquid chamber 106 is pressurized, and droplets of the recording liquid are ejected (jetted) from the nozzle 104.

  Then, by returning the voltage applied to the piezoelectric element 121 to the reference potential, the diaphragm 102 is restored to the initial position, and the liquid chamber 106 expands to generate a negative pressure. The recording liquid is filled in 106. Therefore, after the vibration of the meniscus surface of the nozzle 104 is attenuated and stabilized, the operation proceeds to the next droplet discharge.

  Note that the driving method of the head is not limited to the above example (pulling-pushing), and it is also possible to perform striking or pushing depending on the direction to which the driving waveform is given.

  In the image forming apparatus configured as described above, the sheets 22 are separated and fed one by one from the sheet feeding unit, and the sheets 22 fed substantially vertically upward are guided by the guide 25, and the conveyance belt 31 and the counter roller 26, and the leading end is guided by a conveying guide 27 and pressed against the conveying belt 31 by a leading end pressing roller 29, and the conveying direction is changed by approximately 90 °.

  At this time, a positive output and a negative output are alternately and repeatedly applied to the charging roller 34 from an AC bias supply unit, which will be described later, that is, an alternating voltage is applied, and a charging voltage pattern in which the conveying belt 31 alternates, that is, a loop In the sub-scanning direction, which is the direction, plus and minus are alternately charged in a band shape with a predetermined width. When the paper 32 is fed onto the conveying belt 31 that is alternately charged with plus and minus, the paper 22 is attracted to the conveying belt 31 by electrostatic force, and the paper 22 is conveyed in the sub-scanning direction by the circular movement of the conveying belt 31. Is done.

  Therefore, by driving the recording head 11 according to the image signal while moving the carriage 4, ink droplets are ejected onto the stopped paper 22 to record one line, and after the paper 22 is conveyed by a predetermined amount, Record the next line. Upon receiving a recording end signal or a signal that the trailing edge of the paper 22 has reached the recording area, the recording operation is finished and the paper 22 is discharged onto the paper discharge tray 40.

  In the case of double-sided printing, when recording on the front surface (surface to be printed first) is completed, the recording belt 32 is fed into the double-sided paper feeding unit 51 by rotating the conveyor belt 31 in reverse. The paper 22 is reversed (with the back surface being the printing surface), fed again between the counter roller 26 and the conveyor belt 31, controlled in timing, and conveyed by the conveyor bell 31 as described above. After recording on the back surface, the paper is discharged onto the paper discharge tray 40.

Next, an outline of the control unit of the image forming apparatus will be described with reference to the block diagram of FIG.
In the control unit 200, the CPU 211 that controls the entire apparatus, the ROM 202 that stores programs executed by the CPU 211 and other fixed data, the RAM 203 that temporarily stores image data and the like, and the power supply of the apparatus are cut off. 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 includes an I / F 206 for transmitting and receiving data and signals to and from the host side, and a head drive control unit 207 including the head data transfer apparatus according to the present invention for driving and controlling the recording head 11. A head driver (driver IC) 208 for driving the recording head 11 provided on the carriage 4 side, a main scanning motor driving unit 210 for driving the main scanning motor 5, and a sub scanning motor 36 are driven. A sub-scanning motor drive unit 211, an AC bias supply unit 212 that supplies an AC bias to the charging roller 34, detection pulses from the linear encoder 74 and the wheel encoder 236, a detection signal from the temperature sensor 215 that detects the environmental temperature, and An I / O 213 for inputting detection signals from other various sensors is provided. 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 from the host side such as an information processing device such as a personal computer, an image reading device such as an image scanner, an imaging device such as a digital camera, etc. via an I / F 206 via a cable or a network. Receive.

  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 this image data is head-driven. The data is transferred from the control unit 207 to the head driver 208. The dot pattern data for image output may be generated by storing font data in the ROM 202, for example, or the image data is developed into bitmap data by a host-side printer driver and transferred to this apparatus. You may do it.

  The head drive control unit 207 transfers the above-described image data as serial data, and outputs the transfer clock to the head driver 208. In addition to outputting the transfer clock to the head driver 208, the head drive control unit 207 outputs drive pulse pattern data stored in the ROM 202 and read out by the CPU 201. A drive waveform generation unit including a D / A converter for conversion and an amplifier is included, and a drive waveform including one drive pulse or a plurality of drive pulses is output to the head driver 208.

  The head driver 208 selectively selects the drive pulse constituting the drive waveform supplied from the head drive control 207 based on the image data corresponding to one line of the print head 11 inputted serially (actuator means of the print head 11 ( In the head configuration described above, the head 11 is driven by being applied to the piezoelectric element 121). The head driver 208 includes, for example, a shift register for inputting a transfer clock signal and serial data as image data, a latch circuit for latching a resist value of the shift register with a latch signal, and an output value of the latch circuit changing the level. Drive from the head drive control unit 107 by controlling the on / off state of the analog switch array. A required drive pulse included in the waveform is selectively applied to the actuator means of the recording head 11.

  The main scanning motor driving unit 210 calculates a control value based on a target value given from the CPU 201 side and a speed detection value obtained by sampling a detection pulse from the linear encoder 74, and performs main scanning via an internal motor driver. The motor 5 is driven.

  Similarly, the sub-scanning motor drive control unit 211 calculates a control value based on a target value given from the CPU 101 side and a speed detection value obtained by sampling a detection pulse from the wheel encoder 136 to determine an internal motor driver. And the sub-scanning motor 36 is driven.

  Therefore, a first embodiment of a head data transfer apparatus related to data transfer from the head drive control unit 207 to the head driver 208 in this image forming apparatus will be described with reference to FIGS. FIG. 8 is a block diagram for explaining the part related to data transfer, FIG. 9 is a timing chart for data transfer, and FIG. 10 is a diagram for explaining the details of the period T1 in FIG.

  Here, the print heads 301 to 308 are described for each of the nozzle arrays NA and NB of the heads 11k, 11c, 11m, and 11y described above. That is, the print head (first head A row) 301 is the nozzle row NA of the head 11k, the print head (first head B row) 301 is the nozzle row NB of the head 11k, and the print head (second head A row) 303 is the head. 11c nozzle array NA, print head (second head B array) 304 is nozzle array NB of head 11c, print head (third head A array) 305 is nozzle array NA of head 11m, print head (third head B array) ) 306 means the nozzle row NB of the head 11m, the print head (fourth head A row) 307 means the nozzle row NA of the head 11y, and the print head (fourth head B row) 308 means the nozzle row NB of the head 11y.

  From the print head data transfer device 300 that controls data transfer to the recording head 11 in the head drive control 207, each of the print heads 301 to 308 mounted on the recording head 11 via the FPC cable 12. Two transfer clocks S10 and S20 and serial data S21 to S24 are transferred to driver ICs 311 to 318 constituting the head driver 208.

  Here, the transfer clock S10 is input to the driver IC corresponding to the nozzle row A of the same different head. That is, the transfer clock S10 is input to the driver ICs 311, 313, 315, and 317 corresponding to the print heads 301, 303, 305, and 307. The transfer clock S20 is an inverted version of the transfer clock S10. This transfer clock S20 is input to the driver IC corresponding to the nozzle row B of the same different head. That is, the transfer clock S20 is input to the driver ICs 312, 314, 316, and 318 corresponding to the print heads 302, 304, 306, and 308.

  Further, as shown in FIG. 10, the serial data S21 to S24 are data that alternately include data of each nozzle row of the same head for each channel. For example, the serial data S21 includes data for the first nozzle (head 1 / nozzle row A / ch1) of the print head 301, data for the first nozzle (head 2 / nozzle row B / ch1) of the print head 302, and the print head 301. Data for the second nozzle (head 1 / nozzle row A / ch2) are transferred as follows. The same applies to the other serial data S22 to S24.

  With this configuration, as shown in FIG. 10, the driver ICs 301, 313, 315, and 317 receive the data for the nozzle row A of the serial data S21 to S24 at the rising edge (edge with an arrow) of the transfer clock S10. The capture and driver ICs 302, 314, 316, and 318 capture the data of the nozzle row B of the corresponding head at the rising edge of the transfer clock S20.

  At this time, the total number of signal lines on the FPC cable 12 necessary for data transfer is six. Compared with the conventional head data transfer apparatus described with reference to FIGS. The number of lines is greatly reduced.

  As described above, by using a plurality of transfer clocks having different phases, a means for transferring a plurality of data for driving the recording head during one transfer cycle is provided, so that a plurality of data is provided in the same head. By using data for a plurality of different nozzle arrays, the number of signal lines can be reduced, and the size and cost of the apparatus and head can be reduced. In addition, since there is no change in the data capture method of capturing data at the rising edge of the transfer clock, no special circuit change of the driver IC is required, and an increase in cost due to the circuit change can be suppressed.

  In this case, a plurality of transfer clocks having different phases can be generated with a simple configuration by using one transfer clock and a transfer clock obtained by inverting the transfer clocks.

  Next, a second embodiment of the head data transfer apparatus will be described with reference to FIGS. FIG. 11 is a block diagram for explaining a portion related to data transfer, FIG. 12 is a timing chart for data transfer, and FIG. 13 is a diagram for explaining details of a period T2 in FIG.

  In this embodiment, the print head data transfer device 400 that controls data transfer to the recording head 11 in the head drive control 207 sends the print heads 301 to 308 mounted on the recording head 11 via the FPC cable 12. The two transfer clocks S10 and S20 and the serial data S31 to S38 are transferred to the driver ICs 411 to 418 constituting the corresponding head drivers 208.

  Here, the transfer clock S10 and the transfer clock S20 are input to the driver ICs 411 to 418 corresponding to the print heads 301 to 308, respectively.

  Further, the serial data S31 to S38 are data of each channel of the same nozzle row of the same head as shown in FIG. For example, the serial data S31 is data for the first nozzle (head 1 / nozzle row A / ch1) of the print head 301, data for the second nozzle (head 1 / nozzle row A / ch2) of the print head 301, Data for the third nozzle (head 1 / nozzle row A / ch3) of the head 301 is transferred. The same applies to the other serial data S32 to S38.

  With this configuration, as shown in FIG. 13, the driver ICs 401 to 408 take in the data for the odd nozzle channels of the serial data S31 to S38 at the rising edge (edge with an arrow) of the transfer clock S10, and transfer clock. The data of the even nozzle channels of the serial data S31 to S38 corresponding to the rising edge of S20 is taken.

  At this time, when the frequency of the transfer clocks S10 and S20 is 8 mHz, the transfer rate for all heads and all nozzles is 128 Mbps, which is twice that of the transfer clock having the same frequency as the conventional head data transfer device described above. The transfer rate can be realized. In other words, when the required transfer rate is 64 Mbps, the required transfer clock frequency is 4 MHz, and the required transfer rate can be secured with a low transfer clock frequency.

  As described above, by using a plurality of transfer clocks having different phases, a means for transferring a plurality of data for driving the recording head during one transfer cycle is provided, so that a plurality of data is provided in the same head. By using data for the same nozzle channel, it is possible to increase the recording speed by increasing the transfer rate if the transfer clock has the same frequency, and to reduce the transfer clock frequency if the transfer rate is the same. It is possible to improve the stability of the signal and reduce the environmental load such as electromagnetic interference (EMI) caused by the high frequency signal.

1 is an explanatory side view illustrating an overall configuration of a mechanism unit of an image forming apparatus according to the present invention. It is a plane explanatory view of the mechanism part. FIG. 3 is an explanatory diagram illustrating an example of a recording head configuration of the image forming apparatus. FIG. 6 is an explanatory diagram illustrating another example of the recording head configuration. FIG. 6 is a cross-sectional explanatory view along the longitudinal direction of the liquid chamber showing an example of a droplet discharge head that also constitutes a recording head. FIG. 5 is a cross-sectional explanatory view along the lateral direction of the liquid chamber showing an example of a droplet discharge head that also constitutes a recording head. FIG. 2 is a block explanatory diagram illustrating an overview of a control unit in the image forming apparatus. FIG. 3 is a block explanatory diagram of a portion related to data transfer for explaining a first embodiment of a head data transfer device in the control unit. It is a timing chart of data transfer similarly. Similarly, it is an explanatory diagram for explaining the details of the period T1 of FIG. It is a block explanatory drawing of the part concerned in the data transfer explaining 2nd Embodiment of the head data transfer apparatus in the same control part. It is a timing chart of data transfer similarly. Similarly, it is an explanatory view for explaining the details of the period T2 in FIG. It is a block explanatory drawing of the part concerned in the data transfer explaining the conventional head data transfer apparatus. It is a timing chart of data transfer similarly. FIG. 16 is also an explanatory diagram for explaining details of a period T5 in FIG. 15.

Explanation of symbols

DESCRIPTION OF SYMBOLS 4 ... Carriage 5 ... Main scanning motor 11 ... Recording head 11k, 11c, 11m, 11y ... Head NA, NB ... Nozzle row 12 ... FPC cable 22 ... Recording medium (paper)
DESCRIPTION OF SYMBOLS 31 ... Conveyance belt 32 ... Conveyance roller 36 ... Sub-scanning motor 121 ... Piezoelectric element 200 ... Control part 207 ... Head drive control part 208 ... Head driver 300, 400 ... Head data transfer device 301-308 ... Print head 311-318, 411 418 Driver IC

Claims (5)

  In a head data transfer apparatus for transferring data for driving a recording head to a recording head constituted by a plurality of nozzle rows or heads, the plurality of transfer clocks having different phases are used in one transfer cycle. A data transfer apparatus comprising means for transferring a plurality of data for driving a recording head.   2. The data transfer device according to claim 1, wherein the plurality of transfer clocks are two transfer clocks having phases inverted.   3. The data transfer apparatus according to claim 1, wherein the plurality of data are data for a plurality of different nozzle arrays provided in the same head.   3. The data transfer apparatus according to claim 1, wherein the plurality of data are data for different channels of the same nozzle row provided in the same head. 5. An image forming apparatus comprising a recording head composed of a plurality of nozzle rows or heads and forming an image on a recording medium by discharging recording liquid droplets from the recording head. An image forming apparatus comprising the head data transfer device described above.

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