JP2007290245A - Inkjet recording head and inkjet recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a structure of a recording head which facilitates removal of bubbles left in a passage between a filter and each recording element substrate in the full multi inkjet recording head having such a constitution that a plurality of the recording element substrates are arranged zigzag and the filter corresponding to each recording element substrate is installed, and to provide an inkjet recording head high in reliability of printing, and to provide its function recovery method. <P>SOLUTION: The inkjet recording head has both the recording element substrates, in which a plurality of nozzles for ejecting a liquid and a plurality of recording elements that generate an ejection energy are arranged, and a plate for supporting the recording element substrates. The plurality of the recording element substrates are arranged in a nozzle arrangement direction. A filter part corresponding to each recording element substrate is installed in the inkjet recording head. The passage is formed between the recording element substrate and the filter. A common liquid chamber which supplies ink to each recording element substrate is divided to a plurality of chambers, and an ink supply system is furnished for each liquid chamber. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an ink jet recording apparatus that performs a recording operation by discharging a liquid such as ink, and an ink jet recording head used in the recording apparatus. The present invention can be applied to a general printing apparatus, a copying machine, a facsimile having a communication system, an apparatus such as a word processor having a printing unit, or a multifunction recording apparatus combining these apparatuses. In particular, the present invention is suitably applied to a recording apparatus that performs high-speed and high-quality printing.

  Conventionally, an inkjet recording apparatus is low in running cost, can be downsized, and can easily support color image recording using a plurality of colors of ink. Widely used and commercialized.

  On the other hand, as an energy generating element that generates energy for ejecting ink from the ejection port of the recording head, an element that uses an electromechanical transducer such as a piezo element, or an electromagnetic wave such as a laser emits heat to generate heat. There are those that discharge ink droplets by the action of, and those that heat a liquid by an electrothermal conversion element having a heating resistor.

  Among them, an inkjet recording system head that uses thermal energy to eject ink droplets can arrange discharge ports at high density, and therefore can perform high-resolution recording. Among them, recording heads that use electrothermal transducers as energy generating elements are also available for miniaturization, and the advantages of IC technology and microfabrication technology that have made significant progress in technology and improved reliability in the recent semiconductor field. It is advantageous because it can be used in half, easy to mount with high density and inexpensive to manufacture.

  Recently, in order to perform higher-detail printing, a method of creating a nozzle for ejecting ink with high accuracy using a photolithographic technique has been used.

  In recent years, in order to realize high-detail image recording at higher speed, it is also desired to realize a recording head having a longer print width. Specifically, a head having a length of 4 inches to 12 inches has been required.

  Due to such an increase in the length of the head, the number of nozzles increases and the occurrence of ejection failure due to dust on the head becomes a serious problem. In view of this, a configuration is adopted in which one or two filters, which are conventionally provided at the ink supply inlet, are provided in correspondence with each recording element substrate. There are dust generation sources such as dust from each component and dust mixed in the process, but this configuration prevents dust generated from each component in a region where the area of the flow path between the filter and the recording element substrate is extremely small. In addition, a filter can be attached to the dust in the process at the initial stage of the process, and the defect rate due to the dust can be greatly reduced.

As another conventional example, Patent Literature 1 and Patent Literature 2 can be cited.
JP-A-2-000525 Japanese Patent Laid-Open No. 06-191020

  In such a configuration, it is difficult to remove bubbles between the individual filters and the recording element substrate when the ink is filled in the flow path, which causes a decrease in printing reliability.

  In a recording head having a long configuration, it is difficult to recover the function by suction, which is conventionally performed with a short head, in terms of the adhesion of the cap due to the increase in the cap area and the uniform suction recovery across the entire nozzle.

  Conventionally, in such a configuration, the entire supply system is decompressed, and then ink is supplied by supplying ink. However, the function recovery by the same method for a long head has a problem in that the reliability of the recovery is remarkably lowered due to the difficulty in the adhesion of the cap as described above.

  Further, when trying to increase the close contact of the capping, the capping pressure increases and the load on the head increases. This increases the burden on the head structure, which is disadvantageous for cost and reliability.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for recovering the function of an ink jet recording head that is highly reliable and has a low capping load.

In order to achieve the above object, the inkjet recording head of the present invention comprises:
Inkjet recording in which a plurality of recording element substrates in which a plurality of nozzles for discharging liquid and a plurality of recording elements for generating discharge energy are arranged are arranged in the nozzle arrangement direction, and a filter portion corresponding to each recording element substrate is provided In the head, the common liquid chamber for supplying ink to each recording element substrate is separated into a plurality of parts.

  The ink jet recording head of the present invention is a recording head in which a plurality of recording element substrates are arranged in the nozzle arrangement direction and a high printing speed can be achieved by achieving a long printing width. By performing recovery, bubbles between the recording element substrate and the filter can be reduced, and moderate bubbles that do not affect printing can be removed. This eliminates the need for high-level cap adhesion across the entire head, and enables more reliable function recovery.

  As described above, according to the present invention, a plurality of recording element substrates of an ink jet recording head are arranged in the nozzle row direction, and a liquid chamber is divided into a plurality of parts in a full multihead provided with a filter corresponding to each recording element substrate. By doing so, the pressure at the time of recovering the bubble between the filter and the recording element substrate can be reduced, the load on the head and the load on the recovery system can be reduced, and the reliability can be improved.

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

(First embodiment)
FIG. 1 to FIG. 9 are explanatory diagrams for explaining each of the suitable recording head, driving circuit, and ink jet recording apparatus to which the present invention is applied or applied, and their respective relationships. Hereinafter, the entire configuration will be described with reference to these drawings while describing the configuration of each part.

(1) Description of Recording Head As shown in FIG. 1, the recording head H1000 is an electrothermal transducer that generates thermal energy for generating thermal energy for causing film boiling to the ink in accordance with an electrical signal. The recording head is a bubble shooter (registered trademark) side shooter type that performs recording using the.

  As shown in the exploded perspective view of FIG. 2, the recording head H1000 includes a recording element unit H1001 and an ink supply member H1500 of an ink supply unit H1002. Further, as shown in the exploded perspective view of FIG. 3, the recording element unit H1001 includes a recording element substrate H1100, a first plate H1200, an electric wiring substrate H1300, a second plate H1400, and a filter member H1600.

(1-1) Recording Element Unit FIG. 4A is a diagram illustrating the configuration of the recording element substrate H1100, and FIG. 4B is a cross-sectional view taken along line AA shown in FIG. The recording element substrate H1100 has a thin film formed of, for example, a Si substrate H1108 having a thickness of 0.5 to 1 mm. Further, an ink supply port H1101 composed of a long groove-like through-hole is formed as an ink flow path, and electrothermal conversion elements H1102 are arranged in a staggered pattern on each side of the ink supply port H1101, respectively. The electric wiring such as the element H1102 and Al is formed by a film forming technique. An electrode H1103 is provided to supply power to the electrical wiring. The ink supply port H1101 performs anisotropic etching using the crystal orientation of the Si substrate H1108. When the wafer surface has a crystal orientation of <100> and a thickness direction of <111>, the etching proceeds at an angle of about 54.7 degrees by anisotropic etching (KOH, TMAH, humanradine, etc.) . Using this method, etching is performed to a desired depth. A nozzle plate H1110 is provided on the Si substrate H1108, and an ink flow path H1104, a nozzle H1105, and a foaming chamber H1107 corresponding to the electrothermal conversion element H1102 are formed by a photolithography technique. The nozzle H1105 is provided so as to face the electrothermal conversion element H1102, and causes the ink supplied from the ink supply port H1101 to generate bubbles by the electrothermal conversion element H1102 to discharge the ink. .

  The first plate H1200 is made of, for example, an alumina (Al2O3) material having a thickness of 0.5 to 10 mm. The material of the first plate is not limited to alumina, and has a linear expansion coefficient equivalent to that of the material of the recording element substrate H1100 and is equivalent to the thermal conductivity of the material of the recording element substrate H1100. Alternatively, it may be made of a material having an equivalent or higher thermal conductivity. The material of the first plate H1200 is, for example, any of silicon (Si), aluminum nitride (AlN), zirconia, silicon nitride (Si3N4), silicon carbide (SiC), molybdenum (Mo), and tungsten (W). May be. An ink supply port H1201 for supplying ink to the recording element substrate H1100 is formed in the first plate H1200, and the ink supply port H1101 of the recording element substrate H1100 is connected to the ink supply port H1201 of the first plate H1200. Correspondingly, the recording element substrate H1100 is bonded and fixed to the first plate H1200 with high positional accuracy. The adhesive is desirably, for example, a material having a low viscosity, a thin adhesive layer formed on the contact surface, a relatively high hardness after curing, and ink resistance. For example, it is a thermosetting adhesive mainly composed of an epoxy resin, or an ultraviolet curing combined thermosetting adhesive, and the thickness of the adhesive layer is desirably 50 μm or less. The first plate H1200 has an X-direction reference H1204, a Y-direction reference H1205, and a Z-direction reference H1206, which are positioning references.

  The recording element substrates H1100 are arranged in a staggered manner on the first plate H1200 as shown in FIG. 1, and wide recording with the same color is possible. For example, four recording element substrates H1100a, H1100b, H1100c, and H1100d each having a nozzle group length of 1 inch + α are arranged in a staggered manner to enable recording of a width of 4 inches.

  In addition, the end of each ejection element group of each recording element substrate is provided with a region (L) overlapping with the end of the nozzle group of the recording element board adjacent to the staggered pattern in the recording direction. Prevents gaps from being generated by printing. For example, overlapping regions H1109a and H1109b are provided in the nozzle group H1106a and the nozzle group H1106b.

  The electrical wiring substrate H1300 applies an electrical signal for ejecting ink to the recording element substrate H1100, has an opening for incorporating the recording element substrate H1100, and has a second surface on the back surface. The plate H1400 is bonded and fixed. The electric wiring board H1300 has an electrode terminal H1302 corresponding to the electrode H1103 of the recording element board H1100, and an external signal input terminal H1301 for receiving an electric signal from the recording apparatus main body located at the end of the wiring. Yes. The electrical wiring substrate H1300 and the recording element substrate H1100 are electrically connected. For example, the electrode H1103 of the recording element substrate H1100 and the electrode terminal H1302 of the electrical wiring substrate H1300 are connected to a gold wire H1303 (not shown). It is electrically connected by the wire bonding technique used. As a material of the electrical wiring board H1300, for example, a flexible wiring board having a two-layer structure is used, and a surface layer is covered with a polyimide film.

  The second plate H1400 is formed of a SUS plate having a thickness of 0.5 to 1 mm, for example. Note that the material of the second plate is not limited to SUS, and may be made of a material having ink resistance and good flatness. The second plate H1400 has a recording element substrate H1100 bonded and fixed to the first plate H1200 and an opening for taking in the recording element substrate, and is bonded and fixed to the first plate.

  A groove formed by the opening H1402 of the second plate and the side surface of the recording element substrate H1100 is filled with the first sealant H1304, and the electrical mounting portion of the electrical wiring substrate H1300 is sealed. Further, the electrode H1103 of the recording element substrate is sealed with a second sealant H1305 to protect the electrical connection portion from corrosion by ink and external impact.

  Further, a filter member H1600 for removing foreign matters mixed in the ink is bonded and fixed to the back surface side ink supply port H1201 of the first plate H1100.

(1-2) Ink Supply Unit The ink supply member H1500 is formed by resin molding, for example, and includes a common liquid chamber H1501 and a Z-direction reference surface H1502. The Z reference plane H1502 positions and fixes the recording element unit and serves as the Z reference for the recording head H1000.

(1-3) Coupling of Recording Element Unit and Ink Supply Unit As shown in FIG. 2 described above, the recording head H1000 is completed by coupling the recording element unit H1001 to the ink supply member H1500.

  The coupling is performed as follows.

  The opening of the ink supply member H1500 and the recording element unit H1001 are sealed with a third sealant (not shown), and the common liquid chamber H1501 is separated into two chambers and sealed. Then, the Z reference H1502 of the recording element unit H1001 is positioned and fixed to the Z reference H1502 of the ink supply member by, for example, a screw H1900. The third sealant is preferably a sealant that has ink resistance, is cured at room temperature, and is flexible enough to withstand the difference in linear expansion between different materials.

  Further, the external signal input terminal H1301 portion of the recording element unit H1001 is positioned and fixed on the back surface of the ink supply member H1501, for example.

(2) Description of Drive Circuit As shown in FIG. 1, in the recording head H1000 of the present application, four recording element substrates H1100 are accurately arranged on a chip plate H1200, and further, four recording element substrates H1100 are arranged on an electric wiring substrate H1300. It is wired with. FIG. 8 is a circuit diagram showing signal wiring between the four recording element substrates. In the figure, H1100a to H1100d each correspond to four printing element substrates, and each printing element substrate is composed of driving circuits for odd and even two nozzle rows shown in FIGS. HEATO, E and IDATAO, E are taken out separately for each element evenly and oddly, and are indicated by signal names HEAT1-8 and IDATA1-8 for each recording element substrate. Other signals are wired in common between the recording element substrates. LTCLK, DCLK, HEAT 1 to 8, and IDATA 1 to 8 are connected to an external signal input terminal H1301, and VH, GNDH, VDD, and GND that are power supply systems are connected to a power supply terminal H1302.

  FIG. 4 is a diagram showing the configuration of the recording element substrate H1100. On the both sides of the ink supply port H1101, odd-numbered and even-numbered nozzle rows are shifted by half the nozzle pitch. These two drive circuits are formed on the recording element substrate by a semiconductor process, and signals HEATO, E and IDATAO, E are wired independently in each drive circuit, but other signals (DCLK, LTCLK) and The power supplies (VDD, GND, VH, HGND) are common wirings in the recording element substrate. In both the odd and even nozzle rows, 640 nozzles are arranged at a pitch of 600 dpi and are shifted by a half pitch as described above, so that a 1200 dpi, 1280 nozzle is configured as the recording element substrate. Since the drive circuit of each nozzle row is exactly the same, the outline of the drive circuit will be described with reference to FIG. Each of the nozzles 640 is provided with discharge heaters H1102-1 to 1279, and by driving each discharge heater, the ink in the nozzles is foamed and ink droplets are discharged. The 20 discharge heaters are divided into 32 drive blocks, each of which is driven in a time division manner. The drive block is selected by signals BE0-31, and the 20 discharge heaters belonging to the drive block determine whether or not to discharge by turning ON / OFF the transistors E1006-1 to E1006-1.

  The drive of the recording head H1000 will be described with reference to the drive timing chart of FIG. 9 and FIG. The PRINT signal is a pulse signal that gives the timing for starting ejection of one column, and the operation of the drive circuit starts at the rise timing of the pulse. When the drive circuit starts operation, LTCLK is generated first, and several hundreds ps after that, the transfer clock DCLK is output for the transfer data, that is, 25 clocks. Transfer data is output to each signal of IDATA1 to 8 in synchronization with DCLK and serially transferred to a 25-bit shift register E1001. The data stored in the shift register E1001 is stored in the 25-bit latch E1002 at the timing of LTCLK output at the beginning of the next drive block. Therefore, the actual driving is performed according to the first transfer data at the timing when the next block is transferred. The data content transferred here is a total of 25 bits, ie, the drive block number BENB0-4 is 5 bits and the drive data of the electrothermal transducer H1102 driven in that block is 20 bits. The drive blocks BENB0-4 are decoded into BE0-31 by the 5 → 3 decoder E1003 and connected to the base electrodes of the transistors E1005-1-312. Therefore, only one of the 32 transistors E1005-1 to 32 is always driven, and the drive power supply (VH) is supplied only to one end of the electrothermal conversion element belonging to the designated block. . On the other hand, the other ends of the electrothermal transducers H1102-1 to 1279 are connected in parallel by 32 for each segment, and are connected to the collector electrodes of 20 transistors E1006-1 to 20, respectively. The driving of these transistors is controlled by the outputs of AND gates E1004-1 to 20 connected to the base electrode. A 20-bit drive data signal is connected to one input of the AND gate, and pulse signals HEAT1 to 8 for giving timing for actually driving the electrothermal transducer are connected to the other input. Therefore, the transistors E1006-1 to 20 are controlled by AND of the two signals, and as a result, the segment specified by the 20-bit drive data is driven at the pulse timing of HEAT1 to 8. . As described above, when the PRINT signal is activated, the drive circuit starts to operate, the first block is driven first, sequentially becomes 1, 2,..., And finally the 31st block is completely driven. The ejection of all nozzles on the printing element substrate is controlled.

(3) Description of Inkjet Recording Device As shown in FIG. 5, the inkjet recording device M4000 of the present invention includes, for example, recording heads for six colors corresponding to photographic image quality recording. The recording head H1000Bk is a recording head for black ink, the recording head H1000C is for cyan ink, the recording head H1000M is for magenta ink, the recording head H1000Y is for yellow ink, the recording head H1000LC is for light cyan ink, and the recording head H1000LM is light. For magenta ink. These recording heads H1000 are fixedly supported by positioning means and electrical contacts M4002 of a carriage M4001 mounted on the recording apparatus main body M4000.

  These recording heads are controlled by the drive circuit described above to perform recording on a recording medium. 5 is a full-line type in which the recording head has nozzles corresponding to the width of the recording medium, the recording head is fixed, and recording is performed by scanning the recording medium in the direction of the arrow.

  FIG. 10 is a diagram schematically showing a partial cross section of the recording head of the present invention, and FIG. 13 is a diagram showing a schematic diagram of an ink supply recovery system.

  In a full multi-head in which a plurality of recording element substrates are arranged, two liquid chambers common to the plurality of recording element substrates are provided. In this case, one liquid chamber supplies ink to two recording element substrates. Each liquid chamber is provided with two ink outlets at both ends for ink circulation / pressure application during recovery and ink supply during printing. The outline of the recovery procedure is described below. Ink is supplied from the sub tank by the pumps P1 and P2, flows through the liquid chamber, is discharged from the other ink supply port, removes bubbles in the liquid chamber, and is returned to the sub tank. At this time, as shown in FIG. 11, large bubbles stay in the flow path between the filter and the recording element substrate. Next, the valves V1 and V2 are closed, and the air bubbles are pushed out by the pumps P1 and P2 or pressurized from both sides (not shown), whereby the bubbles are pushed out and discharged from the nozzle as shown in FIG. Although the bubble removal state varies depending on the pressure condition and the flow resistance of the nozzle / filter, in the present invention, a good bubble was discharged by dividing the liquid chamber into a common liquid chamber of about 5,000 nozzles. .

  P3 is a pump that supplies ink from the main tank to the sub tank. The ink liquid level of the sub tank is adjusted to maintain the negative pressure on the head discharge port surface within an appropriate range. When the ink in the sub tank is insufficient, the ink is sent from the main tank by the pump P3.

  FIG. 12 schematically shows a partial cross section of a head having a wide print area in which nine recording element substrates are arranged. By dividing the common liquid chamber into three sections, it is possible to discharge the bubbles with good pressure recovery just as in the case of FIG.

  Thus, by separating the liquid chamber into a plurality of parts, the individual recoverability can be made equal, and particularly in the full multi-head, it is an effective structure in terms of obtaining reliable recovery.

FIG. 2 is an external perspective view of the recording head of the present invention. FIG. 3 is an exploded perspective view of the recording head of the present invention. FIG. 3 is an exploded perspective view of a recording element unit. FIG. 4A is a perspective view illustrating a recording element substrate, and FIG. FIG. 6 illustrates an ink jet recording apparatus (full line method). The figure explaining the drive circuit of an odd number nozzle row. The figure explaining the drive circuit of an even number nozzle row. FIG. 4 is a diagram for explaining signal wiring between four recording element substrates. The drive timing chart figure. The cross-sectional schematic diagram of this invention. The figure explaining this invention bubble state. The Example cross-sectional schematic diagram of the present invention. 1 is a schematic diagram of an ink supply recovery system of the present invention.

Explanation of symbols

H1000 recording head H1001 recording element unit H1002 ink supply unit H1100 recording element substrate H1101 ink supply port H1102 electrothermal conversion element H1103 electrode H1104 ink flow path H1105 nozzle H1106 nozzle group H1107 bubbling chamber H1108 Si substrate H1110 nozzle plate H1200 first plate H1201 Ink supply port H1204 X direction reference H1205 Y direction reference H1206 Z direction reference H1300 Electrical wiring board H1301 External signal input terminal H1302 Electrode terminal H1303 Gold wire (not shown)
H1304 First sealant H1305 Second sealant H1400 Second plate H1500 Ink supply member H1501 Liquid chamber (not shown)
H1502 Z reference plane H1504 Ink supply port (not shown)
H1800 Ink tank H1802 Tube H1900 Screw M4000 Inkjet recording device M4001 Carriage M4002 Electrical contact E1001 Shift register E1002 25-bit latch E1003 Decoder E1004 AND gate E1005 Transistor E1006 Transistor K1000 Recording medium

Claims (3)

  A recording element substrate having a plurality of nozzles for discharging liquid, a plurality of recording elements for generating discharge energy, and a plate for supporting the recording element substrate, and a plurality of recording element substrates in the nozzle arrangement direction A common liquid chamber for supplying ink to each recording element substrate is provided in an ink jet recording head that is arranged and has a filter portion corresponding to each recording element substrate and a flow path is formed between the recording element substrate and the filter. An ink jet recording head characterized in that the ink recording head is divided into a plurality of parts and ink outlets are provided at both ends of each liquid chamber.   An ink jet recording apparatus that performs recording using the ink jet recording head according to claim 1.   An ink jet recording apparatus comprising: the ink jet recording head according to claim 1; and function recovery means for circulating and pressurizing a liquid in an ink flow path of the ink jet recording head.

Images