Ink jet recording apparatus

An ink jet recording head includes a plurality of ink ejection outlets, a first member having a plurality of grooves in fluid communication with the ejection outlets, respectively, a second member having a plurality of energy generating elements for producing energy for ejecting ink in the grooves through the ejection outlets, and a clamping unit for clamping the first member with the second member to constitute ink passages with the grooves, wherein the clamping unit has a plurality of pressure regulating mechanism pressure regulating mechanisms, which are independently operable.

FIELD OF THE INVENTION AND RELATED ART 
 The present invention relates to an ink jet recording apparatus, an ink jet
 recording head and an ink jet recording head manufacturing method, in 
 which liquid droplets are ejected through ejection outlet to effect 
 printing. 
 In a recording apparatus such as a printer, copying machine, facsimile 
 machine or the like, an image consisting of dots is recorded on a 
 recording material such as paper, plastic resin thin sheet, cloth or the 
 like. 
 The recording apparatus can be classified into an ink jet type, a wire dot 
 type, a thermal type, an electrophotographic type and the like. Among 
 them, the ink jet type (ink jet recording apparatus) ejects the recording 
 liquid through the ejection outlets of an ink jet recording head to the 
 recording material. Among various types of ink jet method, the type using 
 thermal energy is advantageous in that the responsivity to the recording 
 signal is high and in that the ejection outlets can be manufactured at 
 high density. 
 Recently, the amount of data to be recorded is increased, more 
 particularly, graphic patterns or the like are printed with the result of 
 the greater amount of data to be printed, so that even higher high speed 
 recording is desired. 
 An ink jet recording apparatus of the above-described type and of a 
 so-called full line type having a long ink jet recording head having 
 ejection outlets over the recording material width, is expected as 
 increasing the recording speed. 
 Referring first to FIG. 10, there is schematically shown an example of a 
 conventional ink jet head. 
 As shown in FIG. 10, it is elongated to cover a length of a side of A4 size
 recording sheet (full-line type). 
 In this Figure, designated by a reference numeral 100 is a heater board of 
 Si or the like. On top of this, there are provided electrothermal 
 transducers functioning as ejection energy generating elements and 
 electrode wiring (not shown) for supplying the electric power thereto. 
 Designated by 200 is a top plate of glass or metal or the like. It has a 
 recess manufactured by machining or etching or the like to constitute an 
 ink inlet 209 for receiving recording liquid such as ink, and a common 
 liquid chamber in fluid communication with respective ink passages and 
 with the ink receiving port 209. 
 Each ink passage is provided corresponding to the ejection energy 
 generating element on the heater board 100. The top plate is bonded on the
 heater board 100, and the heater board 100 is bonded and fixed on the base
 plate 300. A confining member 500 functions to connecting and fixing the 
 top plate 200 and the heater board 100. It is threaded on the base plate 
 300 through the wiring board 400. On top of the confining member 500, an 
 end of a confining spring 600 is fixed by a screw. The other end thereof 
 is contacted to the top surface of the top plate 200 to elastically press 
 the top plate 200. By doing so, the top plate 200 can be mechanically 
 urged to the heater board 1. 
 With this structure, if the top plate involves warping or deformation, it 
 is not possible to press the top plate following the warping or 
 deformation, with the result of non-uniform urging force by the confining 
 spring in the direction of the length. If this occurs, gap may be formed 
 between adjacent passages. In the ink jet head of this type, there is a 
 possibility that the pressure wave upon ejecting the recording liquid may 
 be transmitted to the adjacent ink passages with the result of 
 cross-torque. If this occurs, non-uniformity occurs on the recorded image,
 and in addition, ejection failure may occur as a result of the reduction 
 of the ejection speed. Japanese Laid-Open Patent Application No. 
 126943/1994 proposes comb-like confining spring to make the spring urging 
 force uniform. 
 However, when the top plate is to be pressed, it is necessary to correctly 
 align the heater board and the top plate so that the ink passages 
 correspond to the associated ejection energy generating element, 
 respectively. However, with this structure, when the confining spring is 
 mounted before the top plate is mounted, the confining spring is present 
 at a part of the place to be taken by the top plate, and therefore, it is 
 not possible to align and connect the top plate after the confining spring
 is fixed. For this reason, the confining spring is mounted after the top 
 plate is aligned. In this case, however, if the fixing of the confining 
 spring is executed partially, the fixed portion (screw portion) involves 
 concentrated force with the result of the liability of the deformation of 
 the spring, because the urging force by the confining spring is several 
 tens kg in total. Therefore, the uniform urging is difficult. Therefore, 
 in order to apply the uniform urging force by the confining spring, the 
 fixing of the confining spring has to be uniform. In this case, a very 
 bulky apparatus is required with the result of increase manufacturing 
 cost. 
 SUMMARY OF THE INVENTION 
 Accordingly, it is a principal object of the present invention to provide 
 an ink jet recording head, an ink jet recording head manufacturing method,
 and an ink jet recording apparatus, wherein assembling is easy, and a 
 manufacturing apparatus can be downsized and simplified. 
 According to an aspect of present invention, a mechanism is provided to 
 maintain the released and actuated states of the pressure, thus permitting
 easy manufacturing, small size and simplified manufacturing apparatus, 
 easiness in the assembling and low manufacturing cost. 
 In another aspect of the present invention, the pressure can be applied in 
 divided manner, and therefore, the adjustment of the magnitude, order and 
 the load distribution in a direction in which the ejection outlet are 
 arranged, are enabled to assure the connection. 
 According to an aspect of the present invention, there is provided a ink 
 jet recording head comprising: a plurality of ink ejection outlets; a 
 first member having a plurality of grooves in fluid communication with 
 said ejection outlets, respectively; a second member having a plurality of
 energy generating elements for producing energy for ejecting ink in said 
 grooves through said ejection outlets; and a clamping unit for clamping 
 said first member with said second member to constitute ink passages with 
 said grooves, wherein said clamping unit has a plurality of pressure 
 regulating mechanisms, which are independently operable. 
 According to another aspect of the present invention, there is provided an 
 ink jet recording head comprising a plurality of ink ejection outlets; a 
 first member having a plurality of grooves in fluid communication with 
 said ejection outlets, respectively; a second member having a plurality of
 energy generating elements for producing energy for ejecting ink in said 
 grooves through said ejection outlets; and a clamping unit for clamping 
 said first member with said second member to constitute ink passages with 
 said grooves, wherein said clamping unit has a leaf spring member divided 
 into a plurality of urging sections by slits, each section having a 
 through openings, and a spring supporting member for supporting said 
 spring member along an array of said ejection outlets, wherein a pressure 
 regulating mechanism is provided for said urging sections. 
 According to a further aspect, there is provided a manufacturing method for
 manufacturing an ink jet recording head including a plurality of ink 
 ejection outlets; a first member having a plurality of grooves in fluid 
 communication with said ejection outlets, respectively; a second member 
 having a plurality of energy generating elements for producing energy for 
 ejecting ink in said grooves through said ejection outlets; and a clamping
 unit for clamping said first member with said second member to constitute 
 ink passages with said grooves, said method comprising the steps of: 
 connecting said clamping unit to said supporting member, wherein said 
 clamping unit has a leaf spring member divided into a plurality of urging 
 sections by slits, each section having a through openings, and a spring 
 supporting member for supporting said spring member along an array of said
 ejection outlets, wherein a pressure regulating mechanism is provided for 
 said urging sections; regulating pressures of said urging sections; 
 connecting said first member to said second member after said regulating 
 step; releasing the pressure to permit clamping between said first member 
 and said second member.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
 Referring to the accompanying drawings, the embodiments of the invention 
 will be described. 
 Referring to FIGS. 1 and 2, there are shown an ink jet recording head for a
 first embodiment of the present invention. In this embodiment, ink 
 ejection outlets are arranged at a density of 360 dpi (70.5 .mu.m). 
 In FIG. 2, a heater board 100 is provided with 128 ejection energy 
 generating elements 101 at the density of 360 dpi. It is provided with 
 signal pads for driving the ejection energy generating elements 101 at 
 proper timing by external electric signals and pads 102 for receiving 
 electric energy for the driving. 
 The heater board 100 is bonded and fixed on the surface of a base plate 
 300, and is of metal or ceramic material. 
 FIG. 3 illustrates the heater board 100 on the base plate 300. A plurality 
 of heater board 100 per mounted on the base plate 300, and are bonded and 
 fixed by a predetermined thickness of adhesive material 301 at 
 predetermined positions on the base plate 300. The heater board is 
 provided such that the intervals between adjacent ejection energy 
 generating elements at an end of the heater board are the same as the 
 intervals of 70.5 .mu.m at which the ejection energy generating elements 
 101 are arranged. The gaps between the heater boards occurring at this 
 time, are sealed by a sealant 302. The heater board 100 is not limited to 
 the one described above, but one integral heater board is usable. 
 Referring back to FIG. 2, the base plate 300 has a wiring board 400 bonded 
 in the similar manner as in the heater board 100. The plurality of pads 
 102 on the heater board 100 and a plurality of pads 401 on the wiring 
 board 400 for supplying the signal and electric energy, are made in a 
 predetermined corresponding relation. The wiring board 400 is provided 
 with a connection 402 for supplying external printing signals or driving 
 electric energy. 
 Referring to FIGS. 4(a-c) the top plate 200 will be described. In FIGS. 
 4(a-c) the top plate 200 is provided with a plurality of passages 202 
 corresponding to the ejection energy generating elements 100 on the heater
 board 100, orifices 203 in fluid communication with the corresponding 
 passages 202, respectively, to eject the ink toward the recording 
 material, a liquid chamber 201 connected with each of the passages 202 for
 supplying the ink to the liquid passages 202, an ink supply tube for 
 constituting an ink supply passage for supplying the ink from an ink 
 container (not shown) to the liquid chamber 201, an ink supply port 206 
 for supplying the ink to the liquid chamber through the ink supply tube 
 205. The top plate 200 has a length substantially covering the array of 
 the ejection energy generating elements constituted by arranging a 
 plurality of heater boards. 
 Referring back to FIG. 1, the top plate 200 is connected such that the 
 positional relationships between the passages 202 and the ejection energy 
 generating elements 101 on the heater board on the base plate 300, have 
 the predetermined corresponding relationships. 
 The method of connecting them is mechanical clamping using springs or the 
 like. 
 In FIG. 1, a clamping unit 700 for clamping the top plate and the heater 
 board with each other comprises a leaf spring member 600 and a spring 
 fixing member 500 for fixing the leaf spring member. 
 FIGS. 5(a) and 5(b) are a top plan view and a sectional view of the 
 clamping unit. The leaf spring member 600 is of phosphor bronze, stainless
 steel or the like, and it is in the form of an integral leaf spring 
 provided with slits 602. The portions of the leaf spring divided by the 
 slits 602 constitute the urging portion for urging the top plate. The 
 urging portion is provided with a bent portion to increase the spring 
 rigidity for each urging portion. At an end of the bent portion there is 
 provided a through opening 601. The end of the leaf spring adjacent the 
 urging side, has aprons 603 bent downward to effectively urge the top 
 plate 200, at the end of the leaf spring. The free ends of the aprons are 
 machined into an acute angle so that the contact or urging portion to the 
 top plate is within the upper part of the ink passage. By the concentrated
 urging to the ink passage portion, the ink passage walls between the 
 neighborhood of the ejection outlet and the heat generating portion, which
 is most influential to the cross-talk, can be assuredly urged to the 
 heater board. 
 The through openings 601 are effective to permit insertion of a tool for 
 regulating the urging force and also to be an inlet for a sealant for 
 sealing the top plate and the wire bonding portion. The sealing of the top
 plate is effected after it is fixed using the clamping unit. In this case,
 if the sealant is supplied from the opposite ends of the long top plate, 
 the sealant does not extend enough. In view of this, the sealant is 
 injected through the openings provided for the respective urging portions.
 The front end of the through opening is preferably close to the election 
 outlet to provide enough stroke of the spring. More particularly, it is 
 preferably disposed to correspond to a front half region from the center 
 of the depth of the top plate. In addition, the rear end of the through 
 opening is preferably close to the ejection outlet under the condition 
 that the wire bonding portion can be seen therethrough, since then the 
 sealing can be assuredly effected without reducing the spring rigidity. 
 The apron is effective to provide space between the leaf spring and the top
 plate, and the tool is received by the space. The length of the apron is 
 determined in consideration of the strength of the tool and the rigidity 
 of the spring. 
 According to this embodiment, the integral leaf spring is used, so that the
 position of the urging can be correctly aligned for the respective urging 
 portions, and in addition, the width of the slit can be reduced. 
 A spring fixing member 500 for supporting the leaf spring 600 is of resin 
 material such as PPS, and is integrally formed with the leaf spring member
 600 through insert molding or the like. At this time, in order to 
 reinforce the fixing portion of the leaf spring, the integral formed 
 portion of the leaf spring is provided with a through bore 604, as shown 
 in FIG. 5(b). The leaf spring is bent at this portion. The rear end of the
 leaf spring member is projected through the spring supporting member. The 
 tool is hooked to the rear end of the leaf spring member, so that the 
 urging force can be regulated by the leaf spring member and the spring 
 fixing member only. The clamping unit 700 is fixed on the base plate 300 
 by crimping or screws or the like to clamp the top plate 200 and the 
 heater board 100 by the urging force of the leaf spring member 600. The 
 urging force at this time is 0.2-0.4 kg/mm in this embodiment, although it
 is dependent on the rigidity of the top plate 200. Therefore, in the case 
 of the full line head, the urging force for the entire length, is as large
 as several tens kg. It is preferable that the slits are provided such that
 the urging forces of the respective urging portions are 4-5 kg. In this 
 embodiment, the slits are provided such that the urging portions of the 
 leaf spring member correspond to the respective heater boards. 
 The clamping unit is provided with a mechanism for permitting regulating 
 and releasing the urging force for the respective urging portions. 
 FIG. 6 illustrates the urging force regulating mechanism of the clamping 
 unit. 
 In FIG. 6, the clamping unit is provided with a tool 1000 for regulating 
 the urging force, a first engaging portion 1110 in the tool 1000. The 
 first engaging portion 1110 is inserted into a through opening 601 of the 
 leaf spring member 601, and is engaged with the end of the leaf spring 
 600. A second engaging portion 1210 of the tool 1000 is engaged to the 
 rear end of the fixing portion of the spring fixing member 500. Designated
 by 1300 is a screw for connecting a first member 1100 having the first 
 engaging portion 1110 and a second member 1200 having the second engaging 
 portion 1210. 
 The tool 1000 is in the form of a lever with the fulcrum at the portion 
 contacting the spring confining member 500 and with a operating point of 
 the first engaging portion. By lowering the rear end of the first member, 
 the urging force of the leaf spring urging portion can be regulated. With 
 this state maintained, the screw 1300 is fixed to fix the position of the 
 urging portion at the upper portion. When the top plate 200 is connected 
 with the heater board 100, all of the urging portions of the leaf spring 
 member 600 are fixed at the upper portion as described above, and in this 
 state, the top plate 200 is mounted. After the completion of the alignment
 of the top plate 200, the tool 100 is removed in the reversed order, by 
 which the urging force of the urging force is released so that the top 
 plate 200 is fixed. 
 As described above, by the use of the urging force regulating tool, the 
 regulation and release of the urging force can be easily carried out 
 between the top plate 200 and the heater board 100. 
 By disposing a leaf spring member between the top plate and the leaf 
 spring, it is possible to independently adjust the respective urging 
 forces of the urging portions so that better clamped state is provided. By
 effecting the regulation and release of the urging force using the 
 removable tool, the unit can be downsized, and the durability and 
 operativity are improved. 
 A manufacturing method of the ink jet recording head will be described in 
 conjunction with FIG. 7. 
 FIG. 7 shows the manufacturing steps for the ink jet head. In this 
 embodiment, the elongated multi-nozzle head comprises 11 heater boards 
 (HB) and one grooved top plate. 
 First, an aluminum base plate is manufactured through die cast molding to 
 provide a base plate having a heater board support and PCB positioning 
 projections. The supporting portion is provided with an opening for 
 sucking air for the purpose of temporarily fixing a recess for the bonding
 material ejection and the heater board. FIG. 8 schematically shows a base 
 plate die which has been cast molded. In this Figure, it comprises a 
 heater board support 310, a recess 311 in the heater board supporting 
 portion, an adhesive injection groove 312 in communication with the 
 recess, a sucking opening 313, and a positioning projection 314 for the 
 PCB. The hatched portion and the surface of the supporting portion of the 
 base plate are abraded to increase the surface property of the supporting 
 portion, thus reducing the error in the mounting of the heater board. The 
 end portions of the base plate function as the positioning portion for the
 apparatus, so that the manufacturing accuracy of the apparatus can be 
 improved. 
 On the other hand, a plurality of heater boards (HB) have the 
 electrothermal transducer elements through a thin film forming technique 
 on a silicon substrate. 
 Subsequently, the plurality of the heater boards are positioned with high 
 precision using a positioning tool onto the heater board supporting 
 portion of the base plate. The heater board thus correctly positioned is 
 temporarily fixed by sucking the air through the opening by a vacuum 
 system disposed below BP. In this manner, the heater boards are 
 sequentially positioned on the base plate (step a). 
 The adhesive material is supplied through the injection groove of the base 
 plate. The adhesive material extends to the respective recesses in 
 communication with the adhesive injection grooves by capillary force. 
 Thereafter, it is left for a predetermined period to dry the bonding 
 material, by which the heater board is completely secured. Thereafter, the
 vacuum sucking is stopped. If further strong securing is desired, the 
 adhesive material may be injected through the sucking opening (step b). 
 After the completion of the arrangement and fixing of the heater board, the
 base plate and the heater board are machined to remove the step at the 
 ejection side end of the heater board. By doing so, the top plate is 
 abutted to the ejection side end of the heater board, as will be described
 hereinafter, and the edge machining step is effective to avoid the 
 crosstalk (step c). 
 Subsequently, PCB (wiring board) is bonded to the base plate with the 
 correct positioning using the positioning projections described 
 hereinbefore. By doing so, the electrode pads on the PCB and the electrode
 pads on the heater board are aligned with a predetermined positional 
 relationship. Then, the electrode pad of the PCB and the electrode pad on 
 the heater board are electrically connected by wire bonding. In this step,
 the electroconductivity of the wire bonding is checked (step d). 
 Subsequently, a clamping unit for contacting the top plate to the heater 
 board on the BP (Base plate), is mounted. The clamping unit comprises a 
 leaf spring member for urging the top plate to the heater board and a 
 spring supporting member for supporting the leaf spring. The leaf spring 
 has a plurality of slits to provide a plurality of divided urging 
 portions. Each urging portion is provided with a through opening, through 
 which a tool is inserted to regulate and release the urging force for the 
 urging portions. 
 When the clamping unit is fixed to the PCB, a fixing member for the 
 clamping unit is connected to BP (Base plate) through the PCB, and it may 
 be fixed by screws or thermal crimp (step e). 
 In order to connect the top plate to the heater board, the urging forces of
 the urging portions are regulated by the tool (step f). 
 After sufficient space is assured on the heater board, the alignment 
 operation is carried out between the ink passages and the ejection energy 
 generating elements, and the top plate is connected with the heater board 
 (step g). 
 By releasing the urging force of the urging portion, the top plate is 
 securedly fixed. In the releasing step, the urging force is released from 
 the central portion toward the end portions. By doing so, the warp of the 
 top plate can be corrected, and the deformation escapes toward the other 
 side, by which the satisfactory clamping is assured over the entire length
 of the heater board. After the urging force is released, the tool is 
 removed from the recording head (step h). 
 The ink supply unit is fixed on the base plate by thermal fusing or the 
 like to the position where the ink supply tube is connected to each end of
 the top plate. By the ink supply unit, the ink is supplied to the top 
 plate. The ink may be supplied in both directions, or may be supplied one 
 way and the ink is circulated. In the connection portion with the ink 
 supply unit, a filter is provided to trap bubbles (step i). 
 Finally, a heat cover is mounted to cover the base plate, and a sealing 
 material is injected to the top plate connecting portion and the wire 
 bonding portion through windows provided at positions corresponding to the
 urging portions of the head cover (steps i and k). 
 Referring to FIGS. 11-14, a second embodiment of the present invention will
 be described. FIG. 11 is a schematic perspective view of an ink jet 
 recording head according to the second embodiment. FIG. 12 is a sectional 
 view thereof when the pressure between the top plate and the heater board 
 is released. FIG. 13 is a schematic perspective view of a charge pin. FIG.
 14 is a sectional view of the elements of FIG. 11. As shown in FIG. 11, a 
 confining spring 600 is mounted on a confining spring unit 500. The 
 confining spring unit 500 is fixed on the base plate 300 by crimping or 
 screws or the like. By the spring force of the confining spring 600, the 
 top plate 200 and the heater board 100 are clamped. The spring force for 
 this purpose is 0.2-0.4 kg/mm, although it is dependent on the rigidity of
 the top plate 200. 
 When the top plate 200 is fixed on the base plate 300, urging force 
 producing unit constituted by the confining spring unit 500, the confining
 spring 600 and the charge pin 700 shown in FIGS. 12 and 13, is used, so 
 that the spring force of the confining spring 600 is not imparted to the 
 top plate 200. The unit for producing the clamping force is provided with 
 a mechanism for releasing the urging force and for maintaining the 
 clamping state. 
 The confining spring unit 500 is provided with a plurality of through holes
 in the form of a key hole, as shown in FIG. 11. The confining spring 600, 
 as shown in FIG. 12, a plate-like member bent at two portions and a 
 U-shaped member connected thereto. It is accommodated below the through 
 opening in the confining spring unit 500 so that the plalte-like member is
 at the top. Only the plate-like member is projected to the outside of the 
 confining spring unit 500 to be capable of urging the top plate 200. 
 The charge pin 700 is inserted through the through opening in the confining
 spring unit 500. As shown in FIG. 13, the inserting portion is provided 
 with a locking portion 700b for maintaining the state of insertion. In the
 non-insertion portion, there is provided a stop 700a in the form of "L" 
 for rotation control. The stop 700a abuts the confining spring unit 500 
 when the charge pin 700 is rotated, so that the amount of rotation is 
 controlled. In order to determine the direction of the charge pin 700, a 
 D-cut portion is provided at the top, so that the correct insertion, 
 alignment and rotation are facilitated. 
 The charge pin 700 of the above structure is inserted into the spring unit 
 500 and is rotated, and is locked. By this, the contact portion between 
 the plate-like member and the U-shaped member, is changed to raise the end
 position of the plate-like member functioning as the portion for confining
 the top plate 200, so that the clamping force to the top plate 200 is 
 released. 
 When the top plate 200 and the heater board 100 are clamped, the charge pin
 700 is inserted into the confining spring unit 500, as shown in FIG. 12, 
 by which the clamping force to the top plate 200 is released. The 
 confining spring unit 500 and the base plate 300 are aligned with each 
 other and are fixed together. Thereafter, the charge pin 700 is rotated in
 the opposite direction, and is removed. By this, the end of the confining 
 spring 600 is brought into contact with the top plate 200, as shown in 
 FIG. 14, so that the top plate 200 and the heater board are clamped. 
 As described above, by the operation of the charge pin in the up and down 
 direction and the rotational direction, the top plate 200 and the heater 
 board 100 are clamped or released without difficulty. 
 In the line type head shown in this embodiment, the total clamping load is 
 as large as several tens of kilograms, and therefore, the division is 
 effected so that the spring force of a spring is 4-5 kg or lower. It is 
 preferable that the clamping is effected from the center toward the ends, 
 since then the top plate follows the warpage or curve or deflection of the
 base plate so as to provide the satisfactory clamping. Providing a member 
 between the comfining spring and the confining spring unit so as to permit
 independent adjustment of the respective confining forces is preferable. 
 As in this embodiment, by providing the clamping force controlling member 
 (charging pin) which is mountable and demountable, so that the unit is 
 downsized, and the durability and the operativity are improved. 
 Referring to FIGS. 15-17, a third embodiment will be described. FIG. 15 is 
 a schematic perspective view of an ink Jet recording head according to a 
 third embodiment of the present invention. FIG. 16 is a sectional view 
 when the top late 3200 and the heater board 3100 are clamped, and FIG. 17 
 shows them in the released state. 
 As shown in FIG. 15, a supporting plate 3510 having a L-shaped 
 cross-section, is fixed on the base plate 3300 by crimping or by screws. 
 An L-shaped confining member 3610 is fixed on a wiring board 3400 with its
 one end as a pivot. The other end (open end) is above the top plate 
 surface. It is urged by in adjusting screw 3520 at the top to transmit the
 clamping force for between the top plate 3200 and the heater board 3100. 
 The description will be made as to when the urging force released state 
 and the urging force applied state. 
 As shown in FIG. 16, in the released state (mounting process), it is fixed 
 to the supporting member 3510 by the charging screw 3530. 
 The adjusting screw 3520 is set so as to avoid abutment to the confining 
 member 3610. 
 With this state, the charge screw 3530 is rotated to release the threaded 
 state with the confining member 3610 is removed to free the confining 
 member 3610. The end of the confining member 3610 is contacted to the top 
 plate 3200 only by its weight, and therefore, without any clamping force. 
 By rotating the adjusting screw, as shown in FIG. 17, the confining member 
 3610 is urged to apply the clamping force between the top plate 3200 and 
 the heater board 3110. The clamping force can be adjusted by controlling 
 the torque of the adjusting screw 3520 and the screw rotational angle or 
 the like. 
 Thus, only by the control of the adjusting screw, the clamping force 
 between the top plate 3200 and the heater board 3100 can be controlled. 
 Thus, the structure of the apparatus is simple with reduced cost and easy 
 manufacturing. 
 FIG. 9 shows an example of an ink jet recording apparatus incorporating the
 ink jet recording head according to an embodiment of the present 
 invention. 
 As shown in FIG. 9, the ink jet recording apparatus is provided with 
 line-type heads 2201a-2201d. The line type heads 2201a-2201d, are fixed to
 be extended in parallel with each other with a predetermined gap in X 
 direction by a holder 2202. In the bottom surface of each of the recording
 heads 2201a-2201d, 3456 ejection outlets are provided directed downward 
 and arranged in one line at the density of 16 ejection outlets per 1 mm. 
 This permits the recording on the width of 218 mm. Each of the recording 
 heads 2201a-2201d is a type of using thermal energy, and the ejection is 
 controlled by a head driver 2220. 
 A head unit is constituted by heads 2201a-2201d and a holder 202. The head 
 unit is movable up and down by head moving means 224. 
 Below the heads 2201a-2201d, head cap 2203a-2203d are disposed adjacent to 
 each other and corresponding to the associated heads 2201a-2201d. In the 
 head caps 2203a-2203d, ink absorbing materials such as sponge material are
 provided. 
 The caps 2203a-2203d are fixed by an unshown holder, and the capping unit 
 includes the holder and the caps 2203a and 2203d. The cap unit is movable 
 in X direction by a cap moving means 2225. Each of the recording heads 
 2201a-2201d, is supplied with either of cyan, magenta, yellow and black 
 color ink through the associated ink supply tube 2205a-2205d from the 
 associated ink container 2204a-2204d to permit color recording. 
 The ink supply uses capillary force of the head ejection outlet, and the 
 liquid surface level in each of the ink containers 2204a-2204d is lower 
 than a predetermined amount than the ejection outlet position. 
 The apparatus is provided with an electrically chargeable seamless belt 
 2204 for carrying a recording sheet 227 (recording material). 
 The belt is extended through a predetermined path around a driving roller 
 2207, idler rollers 2209, 2209a and a tension roller 2210. The belt is 
 rotated by a belt driving motor 2208 connected to the driving roller 2207 
 and driven by a motor driver 2221. 
 The belt 2206 travels in the direction X immediately below the ejection 
 outlets of the heads 2201a-2201d. Here, the downward deviation is 
 suppressed by the fixing member 2226. 
 Designated by a reference numeral 2217 is a cleaning unit for removing 
 paper dust or the like from the surface of the belt 2202. 
 Reference numeral 2212 is a charger for electrically charging the belt 
 2206. The charger 2212 is actuated or deactuated by a charger driver 2222 
 so that the recording sheet is attracted on the belt 2206 by electrostatic
 attraction force. 
 Before and after the charger 2212, there are provided pinch rollers 2211 
 and 2211a to cooperate with the idler rollers 2209 and 2209a to urge the 
 recording sheet 2227 to the belt 2206. 
 Reference numeral 2232 designates a sheet feeding cassette. The recording 
 sheets 2227 in the cassette is fed out one-by-one by a pick up roller 2216
 driven by a motor driver 2223. It is further fed to a mountain like guide 
 2213 in X direction by feeding roller 2214 and a pinch roller 2215 driven 
 by the driver 2223. The guide 2213 defines a mountain like space to permit
 deformation of the recording sheet. 
 Reference numeral 2218 designates a sheet discharge tray to which the 
 recording sheet is discharged after the printing or recording operation. 
 The above-described head driver 2220, head moving means 2224, cap moving 
 means 2225, motor drivers 2221 and 2223 and the charger driver 2222 are 
 all controlled by a control circuit 2219. In the embodiments described 
 above, the ink is used as the liquid. In place thereof, however, the use 
 can be made with an ink which is solid under the room temperature or 
 lower, but softened or liquefied at the room temperature. In the ink jet 
 recording system, the ink itself is kept at the temperature of 30-70) 
 .degree. C. to stabilize the ink viscosity within a predetermined range. 
 Therefore, the ink is usable if it is in the form of liquid upon the 
 recording signal application. The ink may be solid if it is liquefied upon
 heating. 
 The present invention is applicable to a textile printer or to a textile 
 printing system incorporating the textile printer and the pre-processing 
 apparatus and a post-processing apparatus to which the long size ink jet 
 head is highly desirable. Therefore, fine and high quality print is 
 permitted in the textile printing apparatus and system. 
 In addition, the present invention is also applicable to a facsimile 
 machine, a copying machine, or printer, and in that case, the prints 
 without image disturbance can be formed. 
 The present invention is particularly suitably usable in an ink jet 
 recording head and recording apparatus wherein thermal energy by an 
 electrothermal transducer, laser beam or the like is used to cause a 
 change of state of the ink to eject or discharge the ink. This is because 
 the high density of the picture elements and the high resolution of the 
 recording are possible. 
 The typical structure and the operational principle are preferably the ones
 disclosed in U.S. Pat. Nos. 4,723,129 and 4,740,796. The principle and 
 structure are applicable to a so-called on-demand type recording system 
 and a continuous type recording system. Particularly, however, it is 
 suitable for the on-demand type because the principle is such that at 
 least one driving signal is applied to an electrothermal transducer 
 disposed on a liquid (ink) retaining sheet or liquid passage, the driving 
 signal being enough to provide such a quick temperature rise beyond a 
 departure from nucleation boiling point, by which the thermal energy is 
 provided by the electrothermal transducer to produce film boiling on the 
 heating portion of the recording head, whereby a bubble can be formed in 
 the liquid (ink) corresponding to each of the driving signals. By the 
 production, development and contraction of the the bubble, the liquid 
 (ink) is ejected through an ejection outlet to produce at least one 
 droplet. The driving signal is preferably in the form of a pulse, because 
 the development and contraction of the bubble can be effected 
 instantaneously, and therefore, the liquid (ink) is ejected with quick 
 response. The driving signal in the form of the pulse is preferably such 
 as disclosed in U.S. Pat. Nos. 4,463,359 and 4,345,262. In addition, the 
 temperature increasing rate of the heating surface is preferably such as 
 disclosed in U.S. Pat. No. 4,313,124. 
 The structure of the recording head may be as shown in U.S. Pat. Nos. 
 4,558,333 and 4,459,600 wherein the heating portion is disposed at a bent 
 portion, as well as the structure of the combination of the ejection 
 outlet, liquid passage and the electrothermal transducer as disclosed in 
 the above-mentioned patents. In addition, the present invention is 
 applicable to the structure disclosed in Japanese Laid-Open Patent 
 Application No. 123670/1984 wherein a common slit is used as the ejection 
 outlet for plural electrothermal transducers, and to the structure 
 disclosed in Japanese Laid-Open Patent Application No. 138461/1984 wherein
 an opening for absorbing pressure wave of the thermal energy is formed 
 corresponding to the ejecting portion. 
 The provisions of the recovery means and/or the auxiliary means for the 
 preliminary operation are preferable, because they can further stabilize 
 the effects of the present invention. As for such means, there are capping
 means for the recording head, cleaning means therefor, pressing or sucking
 means, preliminary heating means which may be the electrothermal 
 transducer, an additional heating element or a combination thereof. Also, 
 means for effecting preliminary ejection (not for the recording operation)
 can stabilize the recording operation. 
 The ink jet recording apparatus may be used as an output terminal of an 
 information processing apparatus such as computer or the like, as a 
 copying apparatus combined with an image reader or the like, or as a 
 facsimile machine having information sending and receiving functions. 
 While the invention has been described with reference to the structures 
 disclosed herein, it is not confined to the details set forth and this 
 application is intended to cover such modifications or changes as may come
 within the purposes of the improvements or the scope of the following 
 claims.