JP2005161633A - Inkjet recording head and inkjet recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize high image quality recording and stable discharge operation by curbing the dispersion of a temperature distribution of a liquid inside an ink reservoir and checking a temperature rise in the liquid. <P>SOLUTION: The full line-type inkjet recording head 20 has a recording element substrate 10 equipped with a plurality of discharge apertures 2a arranged in a row and a heater 3 for heating intended for discharging the ink from the discharge apertures 2a. The ink reservoir part 15a is formed along the arranged discharge apertures 2a so as to allow the supply of an ink to each discharge aperture 2. A supply flow path 13a for supplying the ink to the ink reservoir 15a communicates with the side part of the ink reservoir part 15a and the distance between the communications part and each arranged discharge aperture 2a is almost equal . <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an ink jet recording head and an ink jet recording apparatus that perform recording by discharging a liquid such as ink onto a recording surface of a recording material.

  The ink jet recording apparatus is a so-called non-impact recording type recording apparatus, which can record on high-speed recording and various recording media (recording materials), and hardly generates noise during recording. Have. For this reason, it is widely adopted as a device that bears a recording mechanism such as a printer, a word processor, a facsimile machine, and a copying machine.

  Recently, images with a large amount of data such as graphics have been recorded, and higher-speed recording has been demanded. On the other hand, a so-called full-line type ink jet recording head in which ejection openings are arranged over the entire width of the recording material and a recording apparatus including the ink jet recording head are greatly expected to improve the recording speed. .

  Recording by an ink jet recording apparatus is performed by ejecting ink as fine droplets from an ejection port and adhering to a recording material, and there is a method using an electrothermal conversion element to give the ejection energy. In an ink jet recording head using an electrothermal conversion element, an electrothermal conversion element is provided in a nozzle, and an electric pulse serving as a recording signal is applied thereto to give thermal energy to the ink, which is caused by a phase change of the ink at that time. The bubble pressure at the time of foaming (boiling) is used for ink ejection.

  5 and 6 show an example of a conventional ink jet recording head. FIG. 5 is a perspective view showing an example of the peripheral structure of the ejection opening of the ink jet recording head, and FIG. 6 is a cross-sectional view taken along line YY of FIG.

  An inkjet recording head 220 shown in FIGS. 5 and 6 includes a discharge port plate 202 having a plurality of discharge ports 202a arranged over the entire width of the recording material, and supports the recording element substrate 210 that discharges ink and the recording element substrate 210. So-called full-line type ink jet recording head, comprising: a supporting substrate 208 that is arranged; a circuit substrate 207 that is disposed adjacent to the recording element substrate 210; and a substrate holding member 211 that holds the recording element substrate 210, the circuit substrate 207, and the like. It is.

  The recording element substrate 210 is configured by laminating a discharge port plate 202 on a substrate 201 made of a rectangular plate member. The discharge port plate 202 has an outer shape smaller than that of the substrate 201, and is bonded and fixed to the surface side near the center of the substrate 201. In the discharge port plate 202, a plurality of discharge ports 202 a are arranged in two parallel rows, and the arrangement direction thereof coincides with the longitudinal direction of the substrate 201. As shown in FIG. 6, a space is formed between the ejection port plate 202 and the substrate 201 so as to communicate with the ejection port 202a and an ink storage unit 215a described later. The heater 203 for bubbling the ink is disposed as a discharge energy generating means at a position corresponding to each discharge port 202a in the space. The heater 203 may be composed of an electrothermal conversion element.

  Referring to FIG. 5 again, a plurality of drive elements 205 are arranged in a line on each side of the substrate 201 in the longitudinal direction. The drive element 205 includes a transistor circuit and a logic circuit that drives the transistor circuit, and is electrically connected to the heater 203 to drive and control the heater. The arrangement of the driving element 205 on the substrate 201 may be based on a COB (chip on board) connection method using an anisotropic conductive film, a solder bump, or the like. The recording element substrate 210 configured as described above is fixed on the substrate holding member 211 via a support substrate 208 made of a plate-like member having substantially the same shape as the substrate 201.

  One circuit board 207 is disposed on each side surface of the substrate holding member 211, and the circuit board 207 and the recording element substrate 210 are electrically connected by a flexible substrate 206. Specifically, the flexible substrate 206 is bonded and fixed on the substrate 201 so as to be electrically connected to the drive element 205. An electrical connection portion between the flexible substrate 206 and the driving element 205 is covered and sealed with a sealing agent 212 (see FIG. 6). The sealing material 212 is preferably excellent in sealing properties and ion blocking properties, and may be, for example, an epoxy resin, fluorine resin, or silicon resin. The circuit board 207 is made of a composite material such as glass epoxy, and has an electrical connector (not shown) for inputting an external electrical signal.

  The ink storage unit 215a that supplies ink to each ejection port 202a will be described below.

  As shown in FIG. 6, the ink storage unit 215 a includes a member channel 211 a formed in the substrate holding member 211, a slit 208 s formed in the support substrate 208, and a slit 201 s formed in the substrate 201. The recording element substrate 210 is provided on the back side. The ink reservoir 215a is formed along the arrangement of the ejection ports 202a (see FIG. 5), and the length thereof is substantially equal to the length of the ejection ports 202a in the arrangement direction.

  Referring to FIG. 6 again, the member flow path 211a is formed by grooves formed along the arrangement of the ejection ports 202a, and communicates with ink supply means (not shown) such as an ink tank (not shown) to receive ink. It is configured to be supplied. That is, a channel (not shown) for supplying ink communicates with one end of the member channel 211a, so that ink is supplied into the member channel 211a. The slit 208s is formed as a slit penetrating the support substrate 208, and is formed on the member channel 211a along the member channel 211a. Two slits 201 s are formed on the slit 208 s as slits penetrating the substrate 201. The two slits 201s are parallel to each other and are formed along the arrangement of the discharge ports 202a in the same manner as the member flow paths 211a and the slits 208. The slits 208s and the discharge ports 202a communicate with each other.

  The ink reservoir 215a is configured in this way, and can supply ink to all the ejection ports 202a. At the time of recording, the ink in the ink reservoir 215a is sent from the upstream side to the downstream side in the arrangement direction of the ejection ports 202a and supplied to the respective ejection ports 202a as indicated by arrows in FIG.

Such a configuration of an ink reservoir (ink flow path) that supplies ink to a plurality of ejection ports is disclosed in, for example, Patent Document 1.
Japanese Patent Laid-Open No. 2001-171123

  However, in the ink jet recording head as described above, the ink reservoir is formed so that the ink flows in the direction of arrangement of the ejection openings (nozzle row direction), and therefore the distance of the flow path to each ejection opening becomes non-uniform. As a result, a temperature difference may occur between the upstream side and the downstream side of the ink reservoir. That is, since the ink supplied into the ink storage part is heated by a heater or the like, the temperature becomes higher toward the downstream side. As described above, when the temperature distribution of the ink varies in the ink storage portion, the discharge amount discharged from each discharge port becomes non-uniform, and this causes the density distribution to cause an image with deteriorated image quality. . Such a problem of image quality deterioration is particularly noticeable when a high-duty image is recorded.

  Further, not only the ink itself but also the structure that discharges the ink by the heated ink is heated, and the temperature becomes higher at the downstream side. The structure that ejects ink may become unstable as the temperature increases.

  Accordingly, an object of the present invention is to provide an inkjet recording head that suppresses variations in the temperature distribution of the ink in the ink reservoir and prevents an increase in the temperature of the ink, thereby realizing high-quality recording and stable ejection operation, and the inkjet recording head. It is to provide a recording apparatus provided.

  In order to achieve the above object, the inkjet recording head of the present invention has a plurality of ejection openings for ejecting liquid on a recording material, and a plurality of ejection energy generating means for imparting ejection energy to the liquid corresponds to the ejection opening. At least one recording element substrate provided on the back surface of the recording element substrate, and an ink storage portion that stores liquid supplied to the plurality of discharge ports formed along the array of the discharge ports on the back side of the recording element substrate. In the ink jet recording head having an ink flow path including a supply flow path that communicates with the ink storage section for supplying a liquid to the section, the communication section between the ink storage section and the supply flow path is a discharge port. An intermediate position of the ink storage part in the arrangement direction is included.

  According to the present invention, the communication part between the ink storage part formed along the arrangement of the ejection ports and the flow path for supplying a liquid such as ink to the ink storage part is provided in the ink storage part in the arrangement direction of the ejection ports. By forming it so as to include at least the intermediate position, the distance between the communicating portion and each discharge port is made uniform, so that variation in the liquid temperature distribution in the arrangement direction of the discharge ports can be suppressed. In addition, in such a configuration, since the liquid is not supplied toward the downstream side in the arrangement direction of the discharge ports, it is possible to prevent the liquid from being heated cumulatively and to prevent the liquid from being compared with the conventional configuration. The maximum temperature reached is kept low.

  In the ink jet recording head of the present invention, the communication part between the ink storage part and the flow path may be provided over the whole of the ink storage part in the arrangement direction of the ejection ports. Further, the ink in the ink reservoir may be flowed in a direction substantially orthogonal to the arrangement direction of the ejection ports along the back surface of the recording element substrate. The supply flow path may have a portion that is substantially orthogonal to the arrangement direction of the ejection ports along the back surface of the recording element substrate, and that portion may communicate with the ink storage portion. The ink flow path may be a circulation flow path further including a flow path for guiding the liquid from the ink reservoir to the supply flow path.

  The ink jet recording apparatus of the present invention performs recording using the ink jet recording head of the present invention as described above. In addition, when the ink flow path is a circulation flow path as described above, pump means for circulating the liquid in the flow path may be further provided.

  According to the ink jet recording head and the ink jet recording apparatus of the present invention, variation in the temperature distribution of the liquid in the ink reservoir is suppressed, so that the amount of liquid discharged from each discharge port is made uniform, and high-quality recording is realized. It becomes possible. In addition, since the maximum temperature reached by the liquid is kept low, the structure for ejecting ink is not excessively heated, and a stable ejection operation is realized.

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

  FIG. 1 is a perspective view showing a structure around a discharge port of an inkjet recording head 20 according to an embodiment of the present invention, and FIG. 2A is a cross-sectional view taken along line YY of FIG.

  The ink jet recording head 20 in FIGS. 1 and 2 is obtained by changing the shape of the ink flow path of the ink jet recording head 220 shown in FIGS. 5 and 6, and has the ink flow path 15 as a characteristic part. Other configurations are the same as those of the ink jet recording head 220 in FIGS.

  The ink flow path 15 includes an ink storage portion 15a formed along the arrangement of the ejection ports 2a, and supply flow paths 13a and 13b communicating with the ink storage portion 15a.

  As with the ink storage portion 215a of FIG. 6, the ink storage portion 15a includes a part of the substrate holding member 11, a slit 8s formed on the support substrate 8, and a slit 1s formed on the substrate 1. It is formed along the arrangement of the discharge ports 2a on the back side of the substrate 10 and communicates with each discharge port 2a.

  The flow path 13a is located upstream of the ink reservoir 15a and communicates with ink supply means (not shown) such as an ink tank. In the vicinity of the ink reservoir 15a, the supply channel 13a has a portion that is substantially orthogonal to the arrangement direction of the ejection ports 2a along the back surface of the recording element substrate 10, and this portion communicates with the ink reservoir 15a. Yes. FIG. 2B is a diagram for explaining the arrangement of the flow path 13a, and shows the ink storage portion 15a and the flow path 13a viewed from the upper surface side (discharge port side). As illustrated in FIGS. 2B (a) to 2 (c), the arrangement of the flow path 13a with respect to the ink storage section 15a can be variously changed. In the longitudinal direction of the ink storage section 15a, that is, in the arrangement direction of the ejection ports 2a, 13a may be formed so as to communicate with the entirety of the ink reservoir 15a (see FIG. 2B (a)), a plurality of flow paths 13a may be formed (see FIG. 2B (b)), or One channel 13a may be formed so as to communicate with substantially the center of the ink reservoir 15a (see FIG. 2B (c)). In any case, the communication portion between the flow path 13a and the ink storage portion 15a includes the intermediate position of the ink storage portion 15a, thereby comparing with the conventional configuration in which ink is supplied from one end of the ink storage portion. Thus, the distance from the communication portion to each discharge port 2a is made uniform. That is, in the conventional configuration, since the communication portion is formed at one end of the ink storage portion, a difference in distance from the communication portion to each ejection port 202a (see FIG. 5) is large. However, in this embodiment, the communication portion The difference in distance from each discharge port 2a is relatively small. Accordingly, the temperature of the ink at each ejection port 2a is made uniform, and further, the ink is prevented from being heated cumulatively, so that the temperature rise of the ink can be suppressed. More preferably, as shown in FIG. 2B (a), the flow path 13a is formed so as to communicate with the entire longitudinal direction of the ink storage portion 15a, thereby eliminating the difference in distance from the communication portion to each ejection port 2a. The ink in the ink reservoir 15a may flow along the back surface of the recording element substrate 10 in a direction substantially perpendicular to the arrangement direction of the ejection ports 2a.

  Referring to FIG. 2A again, the flow path 13b is provided on the downstream side of the ink reservoir 15a, and is configured to rejoin the flow path 13a via, for example, pump means (not shown). Thereby, the ink flow path 15 is a circulation flow path. The pump means (not shown) may be provided in the ink jet recording head 20 or may be provided separately from the ink jet recording head 20.

  The ink flow path 15 is configured as described above, and ink from an ink supply means (not shown) passes through the flow path 13a and is supplied to the ink storage portion 15a, and further supplied to each ejection port 2a. Further, by driving a pump means (not shown), the ink circulates in the ink flow path 15 in the directions of arrows a and b in FIG. 2A.

  FIG. 3 is a graph showing the temperature distribution of ink in the ink reservoir 15a. In the graph, the temperature distribution of the ink jet recording head 20 of the present embodiment is indicated by a solid line and a dotted line. The solid line indicates the temperature distribution when the pump means (not shown) is not driven, and the dotted line indicates the pump means ( The temperature distribution when the ink is circulated by driving (not shown) is shown. On the other hand, the alternate long and short dash line indicates the temperature distribution of the conventional inkjet recording head 220.

  As shown in FIG. 3, in the temperature distribution of the conventional inkjet recording head 220, the temperature of the ink is higher toward the downstream side, whereas the temperature distribution of the inkjet recording head 20 according to the present embodiment is It is almost constant and variation in temperature distribution is suppressed. Further, in the case where the ink is circulated by driving the pump means (not shown), the temperature of the ink is generally kept low as compared with the case where the ink is not circulated. Further, the temperature of the ink of the present embodiment on the downstream side is lower than the temperature of the conventional example regardless of the driving of the pump means (not shown).

  As described above, in the ink jet recording head 20 of the present embodiment, the ink flow path 15 is provided so that the ink flows in a direction orthogonal to the arrangement direction of the ejection ports 2a, and the ink reservoir 15a and the flow path 13a are arranged. By making the distances of the flow paths from the communication portion to the respective ejection ports 2a substantially equal, variations in the ink temperature distribution in the arrangement range of the ejection ports 2a can be suppressed. In particular, the temperature of the ink can be kept lower by driving the pump means (not shown) to circulate the ink in the ink flow path 15.

  An ink jet recording apparatus including a plurality of ink jet recording heads 20 according to the present embodiment will be described below. FIG. 4 is a schematic diagram of an inkjet recording apparatus 50 according to an embodiment of the present invention.

  The ink jet recording apparatus 50 discharges the recording paper P fed from the paper feeding unit 50a that feeds the recording paper P that is a recording material, the transport unit 50b that transports the fed recording paper P, and the transport unit 50b. This is a full multi-ink jet printer including a discharge unit 50c and a recording unit 50d that performs recording on the recording paper P.

  The paper feed unit 50a includes a cassette paper feed mechanism 41, a manual paper feed mechanism 42, and a conveyance path 43 and registration rollers that convey the recording paper P fed from the paper feed mechanisms 41 and 42 to the recording unit 50d. 30.

  The cassette paper feeding mechanism 41 and the manual paper feeding mechanism 42 are each provided with a paper tray for holding the recording paper P and feeding rollers 41a and 42a for feeding the recording paper P from the paper tray. By rotating the paper feed rollers 41a and 42a, the recording paper can be separated from the paper tray one by one. Such a mechanism may be a claw separation method or a retard method.

  The feed path 43 is formed so that the transport path from the cassette paper feed mechanism 41 and the transport path from the manual paper feed mechanism 42 merge, and includes a pair of rollers on the downstream side of the feed path 43. A registration roller 30 is disposed. The registration roller 30 is a mechanism for transporting the recording paper P to the recording unit 50d, and a photo sensor (not shown) is disposed in the vicinity of the registration roller 30. The recording paper P is conveyed by, for example, detecting that the recording paper P has hit the nip of the registration roller 30 with a photo sensor and driving the registration roller 30 based on the detection signal. Note that the timing of ink ejection from the inkjet recording head 20 may be adjusted using the start of rotation of the registration roller 30 as a trigger.

  The conveyance of the recording paper P by the registration roller 30 and the feeding roller 42a (or 41a) may be controlled as follows. That is, the feeding roller 42 a is rotated while the registration roller 30 is stopped, and the leading edge of the recording paper P is brought into contact with the nip of the registration roller 30. Here, the feeding roller 42a is further rotated to cause the recording paper P to sag between the registration roller 30 and the feeding roller 42a. Driving the registration roller 30 in this state prevents the recording paper P from being conveyed in an inclined manner.

  The transport unit 50b includes rollers 35a and 35b that are rotatably arranged at a predetermined interval, and a transport belt 37 that is stretched over the rollers 35a and 35b and transports the recording paper P.

  The rollers 35a and 35b are arranged at substantially the same height, the roller 35b located on the downstream side in the conveyance direction of the recording paper P is a driving roller, and one roller 35a is a driven roller. A pulse motor (not shown) or the like is used as a driving source for the driving roller 35b. The conveyor belt 37 is placed between the rollers 35 a and 35 b, and the upper surface thereof is a horizontal recording surface that holds the recording paper P.

  A pressure roller 35c for adjusting the tension of the conveyance belt 37 is disposed between the rollers 35a and 35b. The pressure roller 35 c is biased downward by a spring 36 and applies tension to the conveyor belt 37. On the upper side between the rollers 35a and 35b, a pair of pinch rollers 31 that sandwich the conveyance belt 37 are disposed. Among the pair of pinch rollers 31, a high voltage is applied to the one arranged in the conveyance belt 37, while the one arranged outside the conveyance belt 37 is at the ground potential. The conveyance belt 37 is charged by conveying the recording paper P while the conveyance belt 37 is held between the pinch rollers 31 configured as described above, and the recording paper P is electrostatically adsorbed on the conveyance belt 37.

  The paper discharge unit 50 c includes a paper discharge roller 32 and a paper discharge tray 34 that holds the recording paper P discharged by the paper discharge roller 32. The paper discharge roller 32 is composed of a pair of spurs, and is configured to be able to sandwich and transport the recorded recording paper P. Of the pair of spurs, the spur on the side that transfers the upper surface of the recording paper P, to which the ink has adhered, is formed so that the outer peripheral portion is pointed so that the ink does not adhere.

  The recording unit 50d is configured by holding four inkjet recording heads 20 (20K, 20Y, 20M, and 20C) with a head holder 22. The inkjet recording heads 20K (black), 20Y (yellow), 20M (magenta), and 20C (cyan) are all full-line type recording heads in which ejection openings are arranged over the entire width of the recording area of the recording paper P. The discharge belt is disposed at a predetermined interval at a position where the discharge port faces the upper surface of the conveyance belt 37. Moreover, the arrangement | positioning is 20K, 20Y, 20M, 20C in order from the upstream of a conveyance direction.

  In the ink jet recording apparatus 50 configured as described above, the recording paper P supplied from the paper supply unit 50 a onto the transport belt 37 is electrostatically adsorbed on the transport belt 37, and ink is received from each ink jet recording head 20. An image is recorded by being discharged. Since the inkjet recording apparatus 50 performs recording using the inkjet recording head 20 according to an example of the present invention, the recorded image quality is further improved, and the ejection operation is stabilized.

  The inkjet head 220 and the inkjet recording apparatus 50 of the present embodiment have been described above, but these can be changed as appropriate. For example, the inkjet recording head 20 in FIGS. 1 and 2A has only one recording element substrate 10, but the number of the recording element substrates 10 is not particularly limited. For example, K, Y, It may have four recording element substrates so as to correspond to each color of M and C.

  In FIG. 2A, the configuration of the circulation flow path including the flow path 13c and the pump unit (not shown) has been described. However, the ink flow path 15 is not limited to the circulation flow path. For example, the flow path may be configured by only the ink storage portion 15a and the flow path 13b without providing the flow path 13c and pump means (not shown). Further, the flow path 13a can be variously modified. For example, if the flow path 13a is configured to open and communicate with the lower surface of the ink storage portion 15a (see FIG. 2A) at an intermediate position between the ejection ports 2a, The distance from the communication part to each discharge port 2a becomes more equal. Therefore, the temperature of the ink discharged from each discharge port 2a is made more uniform.

  The ink jet recording head 20 is not limited to the full line type. That is, the arrangement length of the ejection ports 2a (see FIG. 1) may be shorter than the width of the recording material. Further, the number of the discharge ports 2a is not limited to two, and may be one or three or more.

FIG. 2 is a perspective view showing a structure around an ejection port of an inkjet recording head according to an embodiment of the present invention. It is sectional drawing along the YY line of FIG. It is a figure for demonstrating arrangement | positioning of the flow path connected to an ink storage part. 6 is a graph showing the temperature distribution of ink within the arrangement range of ejection openings. 1 is a schematic view of an ink jet recording apparatus according to an embodiment of the present invention. A perspective view showing an example of a structure around a discharge port of a conventional inkjet recording head FIG. 6 is a cross-sectional view taken along line YY of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 Discharge port plate 2a Discharge port 3 Heating heater 5 Drive element 6 Flexible substrate 7 Circuit substrate 8 Support substrate 10 Recording element substrate 11 Substrate holding member 11a Member channel 12 Sealing material 13a, 13b Channel 20 Inkjet recording head 22 Head holder 31 Pinch roller 32 Paper discharge roller 34 Paper discharge tray 35a, 35b Roller 35c Pressure roller 36 Spring 37 Transport belt 41 Cassette paper feed mechanism 41a Feed roller 42 Manual paper feed mechanism 42a Feed roller 43 Transport path 50 Inkjet recording device 50a Paper feed unit 50b Transport unit 50c Paper discharge unit 50d Recording unit

Claims (7)

A plurality of ejection openings for ejecting liquid on the recording material; and at least one recording element substrate provided with a plurality of ejection energy generating means for imparting ejection energy to the liquid corresponding to the ejection openings;
An ink reservoir that stores liquid supplied to the plurality of ejection ports formed along the array of ejection ports on the back side of the recording element substrate, and the ink reservoir for supplying liquid to the ink reservoir In an inkjet recording head having an ink flow path including a supply flow path communicating with
The ink jet recording head, wherein the communication portion between the ink storage portion and the supply flow path includes an intermediate position of the ink storage portion in the arrangement direction of the ejection ports. 2. The ink jet recording head according to claim 1, wherein the communication portion is provided over the whole of the ink storage portion in the arrangement direction of the ejection ports. 3. The ink jet recording head according to claim 1, wherein the ink in the ink reservoir flows in a direction substantially perpendicular to the arrangement direction of the ejection ports along the back surface of the recording element substrate. The supply flow path has a portion substantially perpendicular to the arrangement direction of the ejection ports along the back surface of the recording element substrate, and the portion communicates with the ink storage portion. The inkjet recording head according to any one of claims 1 to 3. The said ink flow path is a circulation flow path further provided with the flow path which guide | induces the said liquid from the said ink storage part to the said supply flow path, The any one of Claim 1 thru | or 4 characterized by the above-mentioned. Inkjet recording head. An ink jet recording apparatus that performs recording using the ink jet recording head according to claim 1. 6. An ink jet recording apparatus comprising: the ink jet recording head according to claim 5; and pump means for circulating a liquid in an ink flow path of the ink jet recording head.

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