Ink jet recording head, cartridge and apparatus

Abstract: An ink jet recording head comprising: a substrate (7) and a ceiling plate (4) constituting discharge ports (13a) for discharging ink and ink passages (13) which become pathways for the ink discharged from the discharge ports (13a), said substrate having a heat energy generating member (3) for generating heat energy to be utilized for discharging of ink; and an ink storage portion which stores ink discharged from said discharge ports, and also is equipped with said substrate at a part thereof, said ink storage portion and said substrate being insert molded to be constituted integrally.

Description: BACKGROUND OF THE INVENTION Field of the invention This invention relates to ink jet apparatus having an ink jet cartridge housing an ink jet head for ejecting droplets of ink. Related background art In recent years, an ink jet head having electrothermal transducers for imparting energy to the ink, has been attracting attention because it is suitably adapted for colour formation and it can be incorporated into a disposable cartridge. In such a head, the electrothermal transducer heats the ink causing an abrupt change of state and the formation of bubbles. These bubbles then cause the ink adjacent to the discharge port to be ejected from the head. Such a structure can be made compact in size and light in weight. Consequently, the density of the discharge ports can be high, thereby increasing the precision of the head. However, when high speed recording has been done by such a head, the heat energy not directly utilised may accumulate. This might, undesirably heat the ink in fine liquid passages resulting in a change of viscosity of the ink. Or may even be enough to release the dissolved gas held within the ink thereby generating unwanted fine bubbles. Accordingly, the present inventors have proposed at the stage of research and development to transmit the heat accumulated in the substrate to the ink storage tank thereby reducing the influence of such unnecessary heating. This type of ink jet head, for example as shown in Fig. 6 and Fig. 7, is known. In such a head a heat transmission member 3 is adhered to the second ink tank 1 with an ink-resistant adhesive 9, then the substrate 2 with a heat generating resistive layer formed thereon, is similarly adhered with adhesive 9. This enables the transmittal of the heat accumulated in the substrate 2 to the second tank. However, to prevent the leakage of ink at the adhered surfaces, a thick layer of adhesive with no gaps is required. In addition, for high efficiency of heat transfer, the heater board 2 and the heat transmitting member 3 must be completely adhered to each other. However, in order to enhance the shooting precision of the discharged ink, particularly in shade recording or full colour recording by use of a plurality of heads, the thickness of the adhesive layer must be controlled to ensure the assembly precision of the heater board. However, it has been very difficult to control the amount and position of the adhesive coating, in order to satisfy both the objects of maintaining the positional precision of the heater board 2 relative to the second ink tank after adhesion and preventing ink leakage. In other words, for ensuring the positional precision of the heater board 2, it is preferable that the adhesive 9 should not be coated too thick. In contrast, for the purpose of preventing ink leakage, it is preferable that the adhesive 9 should be coated rather thicker. If it is coated too thick, there is a possibility that superfluous adhesive may swell out into the liquid passages or the ink tank, thereby restricting the flow. SUMMARY OF THE INVENTION The present invention provides an ink jet recording head (IJH) for discharging ink by utilizing thermal energy in order to form a desired image, the head comprising: a substrate having a discharge port for discharging ink and an ink passage serving an ink path for ink to be discharged from the discharge port, and provided with an energy generating element for generating the thermal energy; an ink storage portion for storing ink; and a heat transmitting member constituting a part of a path communicating the ink storage portion with the ink passage to transmit heat to the ink storage portion, characterized in that the heat transmitting member is insert-molded between the ink storage portion and the substrate. Thereby excess heat generated in the heater board is efficiently transmitted to an ink storage portion of the ink jet recording head. Another advantage of the present invention is that the use of adhesive can be avoided. Thus, the potential problem of adhesive flowing into the ink path thereby restricting the flow is eliminated. Yet another advantage of the present invention is that such an ink jet head can be prepared by a simplified production process. Typically, in such an ink jet head the substrate is also insert molded such that at least a part of the heat transmitting member is contactable with ink within the ink storage portion, thus improving the positional precision of the heater board at the head. Therefore, high quality recording can be accomplished by using a number of recording heads. Also by insert molding, ink leakage from the bonded surface can be prevented. Typically, an ink jet head according to the present invention is housed in an ink jet cartridge capable of being attached to a recording apparatus and further comprising an ink tank for storing ink to be supplied to the recording head. Preferably this ink tank has an absorbing member for storing ink therein. The invention further provides an ink jet recording apparatus comprising an ink jet recording head or an ink jet cartridge in accordance with the invention as set forth above and further comprising means for conveying a recording medium so as to allow an image to be formed on the medium by ink discharged from the recording head. Preferably, this ink jet recording apparatus is equipped with a carriage for freely detachably mounting the ink jet head or the ink jet cartridge. Furthermore, the present invention provides a method of manufacturing an ink jet recording head (IJH) which discharges ink using thermal energy in order to form a desired image, the method comprising the steps of: forming a discharge part having a discharge port for discharging ink; providing an energy generating element for generating the thermal energy for discharging ink from the discharge port; forming an ink storage part for storing ink to be discharged from the discharge port; and forming an ink passage from the storage part to the discharge part, a portion of the passage comprising a heat transmitting member positioned to transmit heat generated by the energy generating element to the storage part, characterised in that the heat transmitting member is insert-molded between the ink storage part and the discharge port. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a side sectional view of the ink jet head according to the present invention. Fig. 2 is a sectional view taken along the A-A' surface in Fig. 1. Fig. 3 is a perspective view of appearance showing an example of the ink jet cartridge according to the present invention. Fig. 4 is a perspective view of appearance showing an example of the ink jet recording apparatus according to the present invention. Fig. 5 is a perspective view of a prior art example before assembling. Fig. 6 is a side sectional view of a prior art example. Fig. 7 is a sectional view taken along the plane B-B' in Fig. 6. DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, the present invention is described in detail. Fig. 1 and Fig. 2 show a constitutional sample of the ink jet head to which the present invention can be suitably applied. Fig. 1 shows a side sectional side view, and Fig. 2 a sectional view taken along the A-A' plane in Fig. 1. The ink jet head IJH to which the present invention is applicable is a head of the bubble jet system which performs recording by use of an electrothermal transducer which generates heat energy for forming film boiling to ink corresponding to electrical signals. In Fig. 1, Fig. 2, 2 is a heater board comprising electothermal transducers (discharging heaters), (not shown) arranged in a plural number of arrays arranged on the Si substrate and electrical wirings (not shown) for feeding power thereto formed by film formation technique. 7 is a wiring substrate for the heater board 2, having a wiring corresponding to the heater board (for example, connected with wire bonding 8), and a pad (not shown) receiving the electrical signals of the main apparatus. The mode of electrical connection is not limited to this, but can take a constitution connected through an anisotropic material or the conventional modes of electrical connection. 4 is a grooved ceiling plate provided with partitioning walls for sectionalizing respectively a plurality of ink passages 13 and the common liquid chamber 14 for housing ink for giving ink to the respective ink passages 13. The second ink tank 1 becomes the structure of the whole ink jet head IJH, with the back lid 6 being adhered or solvent welded, to form the first ink tank 10. Ink from the first tank 10 passes through the ink feeding portion 11 to be led into the ink reservoir portion 12 provided with the filter 5. The filter 5 removes impurities such as dust, etc. which may be mixed in the ink, and when the ink already passed through a filter is introduced, it is not necessarily provided. Ink passes through the filter 5 and then through the ink conduction hole 3a provided at the heat transmitting member 3. Further, ink contacts the lower surface of the heater board and, turning around the side surface, is led to the ink chamber 14, the ink passage 13 formed by bonding of the heater board 2 and the ceiling 4. And, based on the desired signals, ink is heated by the heater (heat-generating resistance member, not shown) provided on the heater board 2 corresponding to the ink passage 13 to form bubbles, which are discharged forwardly of the discharge opening 13 formed at the tip of the ink passage 13 to form a desired image on the recording medium. Here, the heat transmitting member 3 is a member having the effect of transmitting the heat generated at the heater board 2 during performing recording and accumulated without utilization for discharging into ink, and from the standpoint of transmission of heat, it may be preferably a material made of a metal. The ink feeding route from the first ink tank 10 to the ink passage 13 of the recording head is not limited to the above example, but a hole may be formed at the liquid chamber portion of the heater board 2 to make an ink introduction inlet, or alternatively the constitution may be made such that an ink feeding passage may be specially provided from the ink storage portion 12, and a hole formed at the ceiling plate 4 to form an introducing inlet for introducing ink from the ceiling plate side. As shown in Fig. 1 and Fig. 2, in the ink jet head of the present invention, during molding of the second ink tank 1 with a moldable resin forming the second ink tank 1, the heater board 2 and the heat transmission member 3 are insert molded at a part within the ink passage from the ink reservoir portion 12 to the common chamber 14. By thus insert molding the heater board 2 and the heat transmission member 3, the positional precision of the heater board at the head can be improved, whereby there is no variance between a plural number of recording heads in the case of performing shade recording or full-color recording to enable recording of high precision. Also, by insert molding, ink leakage from the bonded surface between the ink passage portion and the heat transmission member or the heater board can be prevented. The resin for forming the second ink tank in this case is filled after registration of the heater board 2 and the heat transmission member 3 so as to be closely contacted with each other. Since the heater board 2 and the heat transmission member 3 are subjected to registration under close contact, the heat accumulated in the heater board 2 can be transmitted with good efficiency to the heat tansmission member 3. Also, by making the constitution of the heat transmission member in direct contact with ink as in this example, the heat can be transmitted into ink to transmit the heat accumulation in the heater board, and also utilized for control of the ink temperature by preventing lowering of ink temperature. The moldable resin for forming the second ink tank 1 may include polyether sulfone, polysulfone, polyether ketone, polyphenylene sulfide, polyethylene terephthalate, polybutylene terephthalate, Noryl, ABS resin, acrylic resin, polycarbon, polyethylene, polypropylene etc. as representative materials. Otherwise, those obtained by synthesizing various materials so as to give materials to obtain desired characteristics may be employed. As the heat transmission member 3 for transmitting the heat accumulated in the heater board 2 to another region, those of the material having ink resistance when directly contacted with ink and/or affecting no deleterious influence on ink, and also having good thermal conductivity, for example, metal materials, specifically titanium or noble metals (gold, silver, platinum, palladium, etc.) and alloys containing these atoms, stainless steel, etc. can be used. Fig. 3 and Fig. 4 are illustrations for explanation of the ink jet cartridge IJC and the main ink jet recording apparatus IJRA, respectively, suitable for practice or application of the ink jet head IJH as described above. In the following, description is made by use of these drawings. The ink jet cartridge IJC in this example, as can be seen from the perspective view in Fig. 3, has a shape having the tip portion of the ink jet head IJH slightly protruded from the front surface of the ink tank IT. The ink jet cartridge IJC is fixed and supported on the carriage mounted on the main ink jet recording apparatus IJRA and also is of the disposable type detachable relative to said carriage. The first ink tank IT 10 storing the ink to be fed to the ink jet head IJH is constituted of a vessel for inserting an ink absorbing member and a lid member for sealing this (both not shown). In the ink tank IT 10 is filled ink, and ink is fed successively to the ink jet head side corresponding to discharging of ink. In this example, the ceiling plate 4 uses a resin excellent in ink resistance, such as polysulfone, polyether sulfone, polyphenylene oxide, polypropylene, etc. The ink jet cartridge IJC constituted as described above is mounted freely detachably according to a predetermined method on the carriage HC of the ink jet recording apparatus IJRA as described below, and controls relative movement of the carriage HC and the recording medium by the predetermined recording signals, to form desired recorded images. As described above, Fig. 4 is a perspective view of appearance showing an example of the ink jet recording apparatus IJRA equipped with the mechanism for the above treatment. In the Figure, 20 is the ink jet head cartridge IJC equipped with the group of nozzles for performing ink discharging as opposed to the recording surface of a recording paper fed onto the platen 24. 16 is the carriage HC for holding the recording head 20, and by connecting to a part of the driving belt 18 which transmits the driving force of the driving motor 17, and being made slidable with the two guide shafts 19A and 19B arranged in parallel to each other, reciprocal movement of the recording head 20 over the entire width of the recording paper is rendered possible. 26 is a head restoring device, and is arranged at one end of the moving route of the recording head 20, for example, at the position opposed to the home position. By the driving force of the motor 22 through the transmission mechanism 23, the head restoring device 26 is actuated to perform capping of the recording head 20. In connection with the capping onto the recording head 20 by the cap portion 26A of the head restoring device 26, ink aspiration by a suitable aspiration means provided in the head restoring device 26 or ink pressure delivery by a suitable pressurization means provided in the ink feeding route to the recording head 20 is peformed to discharge compulsorily ink through the discharge ports, thereby effecting discharge restoration treatment such as removal of thickened ink in the nozzles, etc. Also, the recording head can be protected by application of capping on completion of recording, etc. 31 is a blade as the wiping member formed of a silicone rubber arranged at the side surface of the head restoring device 26. The blade 31 is held in the form of cantilever by the blade holding member 31A, actuated by the motor 22 and the transmission mechanism 23 similarly as the head restoring device 26, whereby engagement of the recording head 20 with the discharge surface becomes possible. By this, at an adequate timing in the recording actuation of the recording head 20, or after the discharge restoration treatment by use of the head restoring device 26, by protruding the blade 31 into the movement route of the recording head, dews formed, wetting or dust, etc. at the discharge surface of the head 20 is wiped off as accompanied with the movement actuation of the head 20. During insert molding, it is preferable to perform molding while ensuring the ink passage by supporting the heater board from above and the heat transmission member from below. Also, the ink jet head may have a constitution equipped only with the second ink tank as the ink storage portion for leading ink to the common liquid chamber, with the first ink tank which is the main as separate body. In other words, the ink reservoir portion 12 forming the heater board 2 and the heat transmission member 3 by insert molding may be constituted as the main tank (first tank) or sub-ink tank (second tank), and the effect of the present invention can be sufficiently obtained. The present invention is described in more detail by referring to Examples. Example 1 While supporting the upper surface, the discharging surface and the rear end of the heater board 2 (7 x 4.7 x 0.5 mm) from above, and the center hold (1.2 mm) of the heat transmission member made of SUS (7 x 5 x 3 mm) and the surface in contact with the ink passage so that the heater board and the heat transmission member may be closely contacted with each other, a polysulfone resin was filled and insert molding was performed to form the second ink tank 1, thus preparing an ink jet head of the head-tank integral form. Comparative example 1 By use of the same heater board and the heat transmission member as in Example 1, the both were fixed by adhesion by use of an epoxy type adhesive for the first ink tank 1 as shown in Fig. 3 to prepare an ink jet head of the head-tank integral form. By use of 50 each of the ink jet heads prepared as described above, the following evaluation tests were conducted. Thermostat storage test: 50 each of the ink jet heads of Example 1 and comparative example 1 were stored in a thermostat storage vessel controlled to 60 °C for one month, and ink leakage of the ink jet head was observed. The results of evaluation are shown in Table 1. Ink leakage among 50 Example 1 0 Comparative example 1 5 As described above, according to the present invention, in a recording head of the type forming a heater board and a heat transmission member in an ink tank, since the heater board and the heat transmission are sealed with the resin constituting the ink tank without use of an adhesive, it has become possible to prevent completely ink leakage from the bonded face. Further, since registration is made directly to the ink tank without use of an adhesive, the positional precision of the heater board is improved very much. Therefore, high quality recording can be accomplished in performing recording by use of a plural number of recording heads (ink jet unit). In addition, no use of an adhesive has made it possible to simplify the production steps. The present invention brings about excellent effects, particularly in the recording head, the recording apparatus of the bubble jet system among the ink jet recording systems. Concerning its representative constitutions and principles, for example, those practiced by use of the basic principle disclosed in U.S. Patents 4,723,129 and 4,740,796 are preferred. This system is applicable to both of the so called on-demand type and continous type, but particularly in the case of the on-demand type, by applying at least one driving signal which gives abrupt temperature elevation in excess of nuclear boiling corresponding to the recording information to the electrothermal transducer arranged corresponding to the sheet or the liquid passage where liquid (ink) is held, heat energy is generated in the electrothermal transducer, thereby causing film boiling to occur on the heat acting surface of the recording head, consequently forming effectively the bubble in the liquid (ink) corresponding one by one to the driving signal. By discharging the liquid (ink) through the opening for discharging by growth, shrinkage of the bubble, at least one droplet is formed. By making the driving signal shaped in pulse, growth and shrinkage of the bubble can be effected instantly and adequately, discharging of the liquid (ink) particularly excellent in response can be more preferably accomplished. As the driving signal shaped in such pulse, those disclosed in U.S. Patents 4,463,359 and 4,345,262 are suitable. Further excellent recording could be performed by employment of the conditions disclosed in U.S. Patent 4,313,124 concerning the temperature elevation rate of the above-mentioned heat acting surface. As the constitution of the recording head, in addition to the combination constitution of discharge port, liquid passage, electrothermal transducer (linear liquid passage or right angle liquid passage), the U.S. Patent 4,558,333 disclosing the constitution having heat acting section arranged at the flexed region, and the constitution by use of U.S. Patent 4,459,600 are also included in the present invention. In addition, the effects of the present invention are effective even when the constitution may be made based on Japanese Laid-open Patent Application No. 59-123670 disclosing the constitution having the common slit as the discharge portion of the electrothermal transducer or Japanese Laid-open Patent Application No. 59-138461 disclosing the constitution having the opening for absorbing the pressure wave of heat energy corresponded to the discharge portion. Further, as the recording head of the full line type having the length corresponding to the width of the maximum recording medium which can be recorded by the recording apparatus, either of the constitution in which its length is satisfied by the combination of a plural number of recording heads as disclosed in the specifications as mentioned above or the constitution as one recording head integrally formed may be employed, but the present invention can further effectively exhibit the effects as described above. In addition, by being mounted on the main apparatus, the present invention is also effective in the case of a recording head of the freely exchangeable chip type which enables electrical connection to the main apparatus and feeding of ink from the main apparatus, or in the case by use of a recording head of the cartridge type provided integrally on the recording head itself. Also, addition of restoration means, preliminary auxiliary means, etc. for the recording head is preferable, because the effects of the present invention can be further stabilized. Specific examples of these may include the capping means, the cleaning means, the pressurization or aspiration means, preliminary heating means by means of electrothermal transducer, another heating element or a combination of these, preliminary discharging mode which performs discharging separate from recording, as effective means for performing stable recording. Further, as the recording mode of the recording apparatus, not only the recording of black, etc. as the main color, but also the recording head may be integrally constituted or a combination of a plurality of heads may be used, but the present invention is also very effective for an apparatus equipped with at least one of plural colors of different colors or full-color by color mixing.

Claims: An ink jet recording head (IJH) for discharging ink by utilizing thermal energy in order to form a desired image, said head comprising: a substrate (2) having a discharge port (13a) for discharging ink and an ink passage (13) serving an ink path for ink to be discharged from said discharge port, and provided with an energy generating element for generating said thermal energy; an ink storage portion (12) for storing ink; and a heat transmitting member (3) constituting a part of a path (3a) communicating said ink storage portion with said ink passage to transmit heat to said ink storage portion, characterized in that said heat transmitting member (3) is insert-molded between said ink storage portion (12) and said substrate (2). An ink jet recording head according to claim 1, wherein said substrate (2) and said heat transmitting member (3) are insert molded such that at least a part of said heat transmitting member is contactable with ink within said ink storage portion (12). An ink jet cartridge (IJC) capable of being attached to a recording apparatus (IJRA), the cartridge having: an ink jet recording head (IJH) as defined in claim 1 or 2, and an ink tank (10) for storing ink to be supplied to said recording head. An ink jet cartridge according to claim 3, wherein said ink tank (10) is equipped with an absorbing member for storing ink therein. An ink jet recording apparatus (IJRA) comprising: an ink jet recording head (IJH) as defined in claim 1 or 2, or an ink jet cartridge (IJC) according to claim 3 or 4, and means (22, 23) for conveying a recording medium so as to allow an image to be formed on the medium by ink discharged from said recording head. An ink jet recording apparatus according to claim 5, wherein said ink jet recording apparatus is equipped with a carriage (16HC) for freely detachably mounting said ink jet head (IJH) or said ink jet cartridge (IJC). A method of manufacturing an ink jet recording head (IJH) which discharges ink using thermal energy in order to form a desired image, the method comprising the steps of: forming a discharge part having a discharge port for discharging ink; providing an energy generating element for generating the thermal energy for discharging ink from said discharge port; forming an ink storage part for storing ink to be discharged from the discharge port; and forming an ink passage from said storage part to said discharge part, a portion of said passage comprising a heat transmitting member positioned to transmit heat generated by said energy generating element to said storage part, characterised in that said heat transmitting member is insert-molded between said ink storage part and said discharge part.

Inventors: KARITA SEIICHIRO, MAEOKA KUNIHIKO, NAKAGOMI HIROSHI, SATOI TSUNENOBU, KARITA, SEIICHIRO, MAEOKA, KUNIHIKO, NAKAGOMI, HIROSHI, SATOI, TSUNENOBU
Applicants: CANON KK, CANON KABUSHIKI KAISHA
Application year: 1990
Main classification: B41J2
IPC codes: B41J2, B41J29