Abstract:
A recording device wherein ink is deposited on recording materials to effect recording including first and second feeders for feeding the recording materials to a recorder, and a discharger for discharging the recording materials from the recorder such that the recording device can be placed horizontally and vertically in use. When the device is placed horizontally the recording materials are conveyed in a generally U-shaped path, and when the device is placed vertically the recording materials are conveyed in a generally rectilinear path.

Description:
This application is a continuation of application Ser. No. 07/583,305 filed Sep. 17, 1990, abandoned. 
    
    
     FIELD OF THE INVENTION AND RELATED ART 
     The present invention relates to an ink jet recording apparatus, more particularly to a recording medium conveying system usable with the ink jet recording apparatus. 
     The ink jet recording apparatus includes not only the elements directly related to the recording operation but also various elements peculiar to the ink ejection type recording. 
     When the liquid ejection is not carried out for a long period of time in a particular ejection outlet or outlets, depending on the nature of the data to be recorded, or when the recording apparatus is left unused for a long period of time, the water content of the ink in the ejection outlet on the ink passage communicating the ejection outlets is evaporated, so that the viscosity of the ink is increased. This can result in failure of ink ejection. When a droplet or droplets of ink or water or foreign matter are deposited on a surface in which the ejection outlets are formed, the ink droplet ejected is influenced by the deposited material with the result of deflection of the ink ejecting direction. To avoid these problems, the ink jet recording apparatus is equipped with various structures for so-called ejection recovery to prevent the ejection failure or the deflection of the ejecting direction. 
     In order to prevent the ejection failure, the ejection recovery system includes the structure for preliminary ejection of the ink for driving out high viscosity ink into an ink receptor material, the structure for sucking the ink through the ejection outlet or an ink chamber to remove the high viscosity ink, and the structure for capping the ejection side surface to prevent evaporation of water content of the ink through the ejection outlets. 
     In order to prevent the deflection of the ejecting direction, there is a structure for wiping the ejecting side surface to remove the foreign matter or the ink droplet deposited adjacent to the ejection outlet. 
     Recently, the ink jet recording apparatus is generally required to effect recording on various recording mediums such as a usual paper envelope. To meet this requirement, a particular structure is used to be responsive to different thicknesses of the recording medium. 
     More particularly, the gap between the recording head and the recording medium during the recording operation is adjusted by an adjusting mechanism to provide an appropriate gap in accordance with the recording medium used. 
     On the other hand, the ink jet recording apparatus, inter alia, the recording head, is recently manufactured through a thin film process or microprocessing as in a semiconductor chip manufacturing, and therefore, a small size and low cost recording head is going to be manufactured. Accordingly, a disposable type recording head having an integral ink container, for example, has been proposed. Under the circumstances, a small size and low cost apparatus easily usable by the users is desired. 
     However, the reduction of the size of the apparatus necessitates reduction of the sizes of various parts and reduction of the space for disposing and operating various constituent elements. As a result, it is desired that the structures of those parts or other parts and the structures among them, are different from those of a relatively large apparatus. 
     Among various parts, a sheet confining plate or plates for regulating the surface of the recording sheet to receive the record onto a platen, are subjected to various limitations when the size of the apparatus is to be reduced. 
     The conventional sheet confining plates themselves are usually made of elastic material constituting leaf springs. If the size of the sheet feeding roller functioning also as a platen is to be reduced, the size of the sheet confining plate is required to be reduced. If, however, the size thereof is simply reduced, the elastic force of the sheet confining plate is increased to such an extent that the elastic force thereby is too strong to properly feed the recording sheet. 
     The elastic member is fatigued in a long term use, with the result that it does not provide the initial set proper urging force. Otherwise, because of the difference in the degree of fatigue, the urging forces of the different sheet confining plates are different with the result of unstable sheet conveyance. 
     The necessity occurs to release the urging force by the sheet confining plates when the recording sheet is removed from the sheet feed passage or when the recording position of the sheet is to be adjusted. Conventionally, the release is effected by rotating the sheet confining plate to be away from the platen. 
     However, if the size of the apparatus is reduced, the space for permitting the rotation without interference with the moving path of the recording head becomes difficult. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide an ink jet recording apparatus having a small size sheet confining plate without necessity of particular space for means for applying urging force thereto, wherein when the sheet confining force by the sheet confining plate is released, there is no interference between the recording head and the sheet confining plate. 
     According to an aspect of the present invention, there is provided an ink jet recording apparatus wherein the ink droplets are ejected to the recording medium to effect the recording, comprising a platen for regulating a recording surface of a recording medium, a sheet confining plate contactable to the platen and an elastic member disposed along a bottom of the apparatus to apply urging force to the sheet member to confine the recording medium on the platen. 
     It is another object of the present invention to provide an ink jet recording apparatus in which the confining force by the sheet confining member can be released. 
     According to another aspect of the present invention, the sheet confining member for directly contacting the platen and the means for applying an urging force thereto are constituted by separate elements, and the urging force applying means is disposed on the bottom of the apparatus, so that the size of the sheet confining member can be reduced, and in addition, no particular space for the force applying means is required. In an embodiment of the present invention, the urging force may be released by releasing the urging force to the sheet confining member. When, for example, the urging force of the sheet confining member to the platen is removed to pull the recording medium from between the sheet confining member and the platen, the sheet confining member does not change its position to a large extent. 
     It is a further object of the present invention to provide a small size ink jet recording apparatus capable of stably feeding the recording medium. 
     According to an aspect of the present invention, a covering member for covering the inside of the apparatus when the apparatus is not used, is utilized as a supporting member for rowels for applying urging force to a sheet discharging roller, and the cover member is urged in a predetermined direction to maintain a constant positional relation between the sheet discharging roller and the rowel. 
     According to an embodiment of the present invention, there is provided an ink jet recording apparatus comprising a discharging roller for discharging recording paper, a rowel for urging the recording paper to the discharging roller to permit recording paper discharging force by the discharging roller to be applied to the recording paper, a member for rotatably supporting the rowel, the supporting member being movable relative to the apparatus, a positioning member engageable with a part of the supporting member and disposed with a predetermined fixed positional relation with the axis of the discharging roller, and urging means for urging the supporting member to the positioning member through the engagement. 
     In the preferred embodiment, the supporting member is the covering member covering the inside of the apparatus. 
     According to this structure, the supporting member for supporting the rowel is press-contacted to the positioning member, and therefore, the constant positional relation is maintained between the rowel and the discharging roller. Since the supporting member and rowel is mounted on the cover member, the size and the required space can be reduced. In addition, the reduction of the number of parts, the accuracy in the manufacturing of the apparatus is increased, so that the good sheet conveying operation is accomplished. 
     It is a further object of the present invention to provide an ink jet recording apparatus wherein a rowel is urged to another member without requiring large space. 
     According to this aspect of the present invention, a rotational shaft of the rowel or the like is made of coil spring, and the urging force is provided by the bending resiliency of the coil spring. 
     According to an embodiment of the present invention, there is provided an ink jet recording apparatus comprising a main rotatable member for feeding a recording medium by its rotation, a follower rotatable member contacted to the main rotatable member with an urging force to rotate following the main rotatable member, wherein the recording operation is effected while the sheet is conveyed by the main and follower rotatable members, a shaft made of coil spring for rotatably supporting the follower rotatable member, by which the shaft provides the urging force by its bending resiliency. 
     According to this structure, when the rowel (follower rotatable member) urges the recording medium onto the sheet discharging roller (main rotatable member), the shaft supporting the follower rotatable member itself provides the urging force, and therefore no additional particular mechanism is required to provide the urging force. Since the shaft of the rowel itself functions as the urging force generating member, so that the size of the apparatus can be reduced without influencing the stability in the sheet conveyance. 
     It is a further object of the present invention to provide a low cost conveying roller usable with an ink jet recording apparatus. 
     According to this aspect of the present invention, a conveying roller comprises a core member having a predetermined shape and a rubber tube covering it. 
     According to an embodiment of the present invention, there is provided a conveying roller for conveying a recording medium in an ink jet recording apparatus, comprising a core member having a predetermined configuration and a tube of elastic material covering the core metal. 
     According to an embodiment of the present invention, there is provided an ink jet recording apparatus wherein a relative movement is imparted between a recording medium and recording means, and an image is formed on the recording medium by ink ejected from the recording means, wherein conveying means for conveying the recording medium includes a stepped core member having a smaller diameter at the longitudinal central portion and elastic material covering the surface of the core member including the central portion. 
     According to the structure, the core member can be produced at relatively low cost, and the elastic tube made of rubber or the like is relatively low in the cost, so that the cost of the conveying roller can be reduced. In addition, the manufacturing process is relatively easy, and a highly accurate conveying roller can be produced. 
     It is a further object of the present invention to provide a small size recording apparatus capable of being used in horizontal and vertical positions. 
     According to this aspect of the present invention, a cover for covering the inside of the apparatus when it is not used, is utilized as a sheet discharge tray, and by properly determining the length or position of the discharge tray, the discharged recording sheets can be stacked in good order, when it is used vertically. 
     According to an embodiment of the present invention, there is provided an ink jet recording apparatus provided with a sheet discharge tray for receiving the discharged recording sheets, wherein the top end of the tray is disposed adjacent to an extension of the sheet discharging line, and the bottom thereof is disposed below the sheet discharge outlet, and in addition, the length of the tray is shorter than the length of the recording sheet discharged. 
     Preferably, the cover member covering the apparatus is used as the tray. 
     According to another embodiment of the present invention, there is provided an ink jet recording apparatus comprising a recording head for forming image record on a recording medium by applying ink thereto, conveying means for conveying the recording medium from a recording medium supply position through the recording head to the medium discharging position, wherein said conveying means includes supplying means for supplying the recording medium to the supply position, moving means for moving the recording medium relative to the recording head at the recording position to convey the medium from the supply position to the discharge position and stacking means for stacking at the sheet discharge position the recording medium on which the recording operation has been performed, wherein said apparatus is operable in a first position wherein the ink is ejected from the recording head substantially horizontally and in a second position wherein the ink is ejected from the recording head substantially vertically, wherein in the first position, the supply means and discharge means are both above the position of the recording head, and in the second position, the supply means and discharge means are at the opposite sides of the recording head, and wherein in the second position, the discharge means is upwardly inclined relative to the horizontal direction, and the stacking means is inclined upwardly relative to the horizontal line, and the engaging position thereof with the main assembly of the apparatus is below a discharge outlet of the recording medium, and the free end of the stacking means is above the engaging portion but is below an extension of a horizontal line of the sheet discharge outlet. 
     In an embodiment, the length of the stacking means is 70-80% of the length of the recording medium. 
     According to this structure, the recording sheet discharged is first brought into contact with the top of the tray after it is conveyed through the air, and it slides on the top end thereof. Thereafter, when the trailing edge of the recording sheet is discharged through the discharge outlet, the sliding movement stops, and the trailing edge of the recording sheet falls downwardly. Therefore, it is stably stacked. Since the discharged recording sheet is not rubbed with the end of the next discharged recording sheet, immediately after the first sheet is discharged, so that the recording surface can be prevented from the contamination. 
     These and other objects, features and advantages of the present invention will become more apparent upon a consideration of the following description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of an ink jet recording apparatus according to an embodiment of the present invention, illustrating an outer appearance thereof. 
     FIG. 2 is a perspective view of the apparatus of FIG. 1, illustrating the major portion of the apparatus without a cover. 
     FIG. 3A is a perspective view of the apparatus of FIG. 1, illustrating a sheet discharging system. 
     FIG. 3B is a side view of the sheet discharging system of FIG. 3A. 
     FIGS. 4A and 4B are side views illustrating different positions of a recording head relative to different recording materials. 
     FIGS. 5A and 5B are rear views of a recording head at its home position in different states. 
     FIG. 6 is a partly broken perspective view of a base for a recovery system mechanism engaged with a base frame. 
     FIGS. 7A, 7B and 7C are perspective views showing a recording head wiping blade and an ink carrier. 
     FIGS. 8 and 9 are an exploded perspective view and a sectional view of a sucking and recovery system for the recording head. 
     FIG. 10 is a timing chart of operations of various parts of the apparatus according to this embodiment. 
     FIG. 11 is a perspective view of a clutch mechanism for transmitting driving force to the recovery system mechanism, in the apparatus of this embodiment. 
     FIGS. 12A, 12B and 12C are side views illustrating engagement among the clutch gear of FIG. 11, a hook and a timing gear. 
     FIGS. 13A and 13B are front views showing engagement among the clutch gear, the hook and the timing gear shown in FIGS. 12A, 12B and 12C. 
     FIGS. 14, 14B, 14C and 14D are side views illustrating sequential operations of the blade and the ink carrier. 
     FIGS. 15A, 15B and 15C are side views illustrating sequential operations of a cap. 
     FIGS. 16A and 16B are side sectional views illustrating an operation of a pump for a recovery sucking operation. 
     FIG. 17 is a timing chart illustrating sequential operations of a preliminary ejection operation or a sucking recovery operation in the apparatus of the embodiment and partly anotherembodiment. 
     FIGS. 18A and 18B are side views of a sheet confining mechanism, according to an embodiment of the present invention. 
     FIG. 19 is a perspective view of a rowel in a sheet discharging system, according to an embodiment of the present invention. 
     FIG. 20 is a front view of a sheet discharging roller according to an embodiment of the present invention. 
     FIG. 21 is a perspective view of an apparatus according to the embodiment of the present invention, used in another position. 
     FIG. 22 is a side sectional view of the apparatus situated as shown in FIG. 21. 
     FIG. 23 is a perspective view illustrating an outer appearance of the recording head. 
     FIGS. 24A and 24B are an exploded perspective view and an outer appearance perspective view of a recording head, according to an embodiment of the present invention. 
     FIGS. 25A, 25B and 25C are a top plan view, a left side view and a right side view of a carrier (carriage) according to an embodiment of the present invention. 
     FIGS. 26A and 26B are a top plan view and a right side view of the carrier shown in FIGS. 25A, 25B and 25C, when it carries the recording head. 
     FIG. 27 is a top plan view of the carrier before the recording head is mounted thereon. 
     FIGS. 28A, 28B and 28C are top plan views of the carrier when the recording head is being mounted thereon. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the accompanying drawings, the preferred embodiments of the invention will be described. 
     In FIG. 1, there is shown an ink jet recording apparatus 100 according to an embodiment of the present invention. The apparatus 100 is used selectively in a generally horizontal setting shown in FIG. 1 or in a vertical setting, as will be described hereinafter. The apparatus 100 is small and light. 
     The apparatus 100 comprises a casing 101, an outer cover 102 and an inner cover 103. When the apparatus 100 is not used, the outer cover 102 covers the inner cover 103, and therefore, the apparatus is compact. The user can accommodate the apparatus in a dedicated case and can carry it around. 
     When the apparatus 100 is used in the horizontal setting, as shown in this FIG., the part indicated by the reference numeral 106 functions as the recording material inlet. The outer cover 102 can be used as the discharge tray. 
     In either of the above cases, the part indicated by a reference numeral 107 functions as a sheet discharge outlet. 
     A positioning hook 105 functions to fix the position of the outer cover 102. Designated by a reference numeral 104 are the operation keys and displays. 
     Referring to FIG. 2, the major part of the apparatus will be described. 
     The apparatus comprises a base frame 1, a left side plate 1a functioning as a guide for a recording medium such as paper and a right side plate 1b. The base frame 1 is provided with an opening (not shown) for rotatably supporting the carrier motor, which will be described hereinafter. 
     A lead arm 1h is for supporting a lead screw 2 in the longitudinal and diametrical direction. The lead screw 2 is rotatably supported on a bearing of the lead arm 1h. The lead arm 1h is securedly fixed on a recovery system base 50 through an unshown plate. 
     The lead screw 2 is provided with lead groove 2a at a predetermined pitch throughout a recording range. The lead screw 2 is provided, at a carrier home position side, with a positioning groove 3b for the positioning at the time of a capping operation by a cap and an operation for correcting improper ink ejection and for preventing improper ejection. The positioning groove 3b is formed along the circumference of the screw shaft. The positioning groove 3b is continuously and smoothly extended from the lead groove 2a through an introduction groove 3c. 
     The lead screw 2 has at its right end a shaft 2g provided coaxially with the lead screw 2, and has a shaft at the left side. The shafts are supported by bearings provided on a front part 1c of the side plate 1b and on the lead arm 1h, respectively. The shafts are rotatably supported by the bearings. A lead pulley 3 is mounted on the lead screw 2 and is provided with the above-described grooves 3b and 3c and a pulley 3a at its end. The pulley 3a receives driving force from a motor 11 through a timing belt 13. 
     The shaft 2g of the lead screw 2 is slidably engaged in a slit of the plate 1c functioning as a guide plate connected to the right side plate 1b and to the base frame 1. It is pushed in its thrust direction by a tongue 10a of a leaf spring 10 and is engaged with a cam slot of a cam plate 50a rotatably supported on a pin fixed on the guide plate 1c. Around the circumferential periphery of the cam plate 50a, meshing teeth are formed which are engageable with a ratchet 10c of the leaf spring 10, by which the cam plate 50a can be locked at a desired rotational position. By the rotation and the locking of the cam plate 50a, the position, in the slot of the guide plate 1c, of the shaft 2g engaging with the cam slot is determined, so that the position of the lead screw 2 at the right end is determined. This adjusting structure is used for adjusting a gap between the recording head and the platen, which will be described hereinafter. 
     A clutch gear 4 is supported for sliding movement in the longitudinal direction on the lead pulley 3. It is fixed on the lead pulley 3 in the rotational direction by a key formed in the lead pulley 3, which will be described hereinafter in conjunction with FIG. 11, so that the rotation of the lead screw 2 is transmitted thereto. A clutch spring 5 is a compression spring to urge the clutch gear 4 toward the lead groove. A limiting member is provided between the clutch gear 4 and the lead pulley 3 to limit the moving range of the clutch gear 4 in the axial direction within a predetermined range. 
     A carrier 6 is supported on the lead screw 2 and is movable along the length of the lead screw 2. The carrier 6 is provided with an urging portion for pushing an end surface of the clutch gear 4 and is formed integrally with a left side of the carrier. The carrier 6 has a lead pin 7 engaging with a lead groove 2a of the lead screw 2 and further has a guiding opening (not shown) to accommodate the lead screw. A lead pin spring 8 has an end mounted to the carrier 6 and has the other end urging the lead pin 7. 
     A recording head 9 is mounted on the carrier 6. In this embodiment, the recording head is in the form of a cartridge containing as a unit a recording head element 9a and an ink container 9b (ink supply source). The cartridge is detachably mountable on the carrier 6, and is disposable when the ink therein is used up. In place of the electrothermal transducer, an electro-mechanical transducer element is usable. The former is preferable since then the ink ejection outlet can be manufactured at a high density and since the manufacturing process is simple. 
     A hook 6c is fixed to a part of the carrier 6 to securely stop the recording head 9 at a capping position or the like. 
     A carrier guiding shaft 51 is slidably engaged with a guiding pin 6b formed on a rear end of the carrier 6. As will be described in conjunction with FIG. 4, the guiding shaft 51 has an eccentric shaft 51a, which is rotatably supported on side plate 51b and 51c provided at the opposite ends of the base frame 1. An end of the shaft 51a adjacent the side plate 51c is fixed to a positioning knob 51d. The positioning knob 51d is generally in the form of a circular disk and is provided, substantially at its center, with a leaf spring 51h in the form of a canti-lever having a channel configuration. The leaf spring 51h is formed by lancing the part of the disk into the channel configuration. The end of the shaft 51a is fixed substantially at the center of the leaf spring 51h. The free end of the leaf spring 51h is provided with a projection 51i for fixing the rotational position of the knob 51d. The rotational position of the shaft 51 is fixed by the engagement between the projection 51i of the leaf spring 51h of the knob 51d and an opening 51e formed in the side plate 51c with the aid of the resilient force of the leaf spring 51h. 
     As shown in FIGS. 4A and 4B, this structure is used to properly adjusting the gap between the recording surface of the recording sheet 40 and ink ejection outlets of the recording head element 9a in accordance with the material of the recording sheet 40. More particularly, the knob 51d is manually rotated, by which the distance between the shaft 51a and the pin 6b is minimum when the shaft 51 takes the position shown in FIG. 4A, and the distance may be maximum when the shaft 51 takes the position shown in FIG. 4B. By doing so, the recording head 9 rotates about the lead screw 2, so that the distance can be fixed to match a relatively thin plain paper (FIG. 4A) or a relatively thick recording paper such as envelopes (larger distance, as shown in FIG. 4B). 
     It should be noted that the above structure is to meet the materials of the recording sheet during the recording operation. The situation is different when the recording head 9 is moved to the recovery system at the left end of FIG. 2 when the recovery process is to be performed. More particularly, at this time, the positional relation has to be constant between the recording head 9 and the recovery system. 
     FIGS. 5A and 5B show the structure for providing the constant positional relation between the recording head and the recovery system during the recovery operation. FIGS. 5A and 5B corresponds to FIGS. 4A and 4B. In FIG. 5A, the engagement between the shaft 51a and the pin 6b is effected without change in the height of the engagement position between the shaft 51 and the pin 6b. In order to maintain the constant height of the engaging position, one of the parallel surfaces of a trapezoidal cam 51g is engaged to the pin 6b. 
     In FIG. 5B, when the recording head 9 moves in the direction that the pin 6b is engaged to the shaft 51a, the height of the engaging position of the pin 6b changes. In consideration of this, the shaft 51 is provided with a tapered portion 51f, and correspondingly, the trapezoidal cam 51g has a tapered surface. Therefore, the height of the engagement between the pin 6b and the shaft 51 is changed by the tapered portion 51f, so that the constant height is maintained when the pin 6b engages to the portion 51a of the shaft. 
     With the structure described above, when the recording head 9 comes to the ejection recovery system, the height of the recording head 9 is always constant, by which the predetermined positional relationship can be maintained between the recovery system and the recording head 9. 
     The number of rotational positions of the recording head 9 is not limited to two, but may be larger with the positions therebetween to meet a larger number of thicknesses of the recording paper. In order to accomplish this, the number of engagement positions between the projection of the knob 51d and the hole 51e of the side plate 51c may be increased. 
     The rotation of the knob 51d is not limited to the manual rotation, but may be automatically effected by rotation the knob 51d in response to a key input corresponding to the recording sheet to be used, for example, utilizing the driving force of a sheet feeding motor or the like. 
     Referring back to FIG. 2, a carrier motor 11 for driving the carrier 6 is in the form of a pulse motor, for example. The left and right surfaces of the motor 11 are provided with pins 11a at aligned positions. The pins 11a (the right side one is not shown) is rotatably mounted in motor mounting holes of a recovery system base 50 movable on the base frame 1. It is a possible alternative that the pins are provided on the recovery system base 50, and the holes are formed in the side of the motor. The carrier motor 11 is, therefore, rotatable about the pins 11a. A projection 11b is extended integrally from the carrier motor 11 in parallel with the output shaft 12 of the motor. The projection 11b is abutted by a motor spring 14. The projection 11b is provided with a columnar projection, to which an end of the motor spring 14 in the form of a coil is fixed. 
     A motor pulley 12 is fixed to the output shaft of the carrier motor 11. The timing belt 13 is stretched between the motor pulley 12 and the pulley 3a mounted on the shaft of the lead screw 2. The motor spring 14 is in the form of a compression spring in this embodiment and is compressed between an end of the lead arm 1h and the spring receiving projection 11b of the carrier motor 11, by which the carrier motor 11 is urged in a direction A to apply tension to the timing belt 13. Designated by a reference numeral 15 is setting shaft, to which the recovery mechanism is mounted. The recovery mechanism includes means, projected from an unshown side plate fixed on the base 50, for cleaning the ejection outlet forming surface, the cap and the other means contributable to the recovery from and the prevention of the improper ejection. 
     As described hereinbefore, the positional relation between the recovery mechanism and the recording head 9 is important. More particularly, the positional relation between the ejection side surface of the recording head 9 and the blade for wiping the ejection side surface is important to maintain the desirable wiping performance, and the distance between the cap and the ejection side surface is important to maintain the capping performance. Therefore, it is desirable that the positional relation is maintained constant between the recovery mechanism and the recording head 9. 
     On the other hand, the recording head 9 effects its recording operation while moving along the lead screw 2 by the driving force transmitted through the lead screw 2. During the recording operation, the distance between the recording sheet 40 and the recovery head 9 is desirably the same irrespective of the position in the movable range of the recording head 9. Therefore, an adjusting mechanism is desirably provided to adjust the distance between the recording head 9 and the recording paper, by which the recording head is shiftable, while maintaining the parallelism relative to the recording paper. However, such an adjusting mechanism may influence the constant positional relation with the recovery system. 
     Accordingly, in this embodiment, the carrier motor 11, the recovery system base 50 mounting the recovery system which will be described in detail hereinafter and the lead screw 2 are movable relative to the base frame 1. 
     The position of the lead screw 2 is adjusted at the opposite ends thereof by moving the base 50 and by moving the cam plate 50a. By the adjustment, the recording head 9 is made movable in parallel with the recording sheet 40. 
     Referring to FIG. 6, there is shown a mechanism in the base 50 for accomplishing this. FIG. 6 is a perspective view of the recovery system base 50 as seen from the opposite side from FIG. 2 and is partly broken away. A guide member 50e is fixed to a side of a groove formed in a backside of the base 50. A groove of the member 50e is engaged with a guide portion of a guiding member 1k having an L-shape, fixed on the base frame 1, by which the movement direction of the base 50 is limited, and in addition, the base 50 is prevented from rising from the base frame 1. 
     As will be understood from FIG. 2, when the cam plate 50b is rotated about a pin 50d mounted on the base 50, the cam surface contacts to a certain part of the surface of the cam slot 1l of the base frame 1 to urge the contact surface. By doing so, the base 50 is moved by the reaction in the direction guided by the member 50e and the member 1k. 
     The cam structure may be modified so that the cam plate is rotated about a predetermined axis by operating a pin engageable with a cam slot formed in the cam plate. 
     By the movement, the carrier motor 11 on the base 50 and the driving system associated with the motor 11, more particularly, the timing belt 13, the pulleys 3 and 12 and the lead screw 2, and the recovery system mechanism mounted on the base 50, are moved, by which the position of the lead screw 2 at the recovery system side is adjusted. 
     On the other hand, a fine adjustment of the other end of the lead screw 2 is accomplished by rotating the cam plate 50a. 
     By the above adjusting operations, the lead screw 2 is made parallel with the recording paper, and the recording head can be adjusted for the movement parallel with the recording sheet. 
     The adjusting operations are performed in this embodiment during the manufacturing of the recording apparatus, using an assembling robot. However, the adjusting operations can be performed by a user after the apparatus is used for a long period of time, or at the time of the other repairing operations. 
     Referring to FIGS. 7A, 7B and 7C with continued reference to FIG. 2, the description will be made as to means for cleaning the ejection side surface of the recording head, which is a part of the recovery system. 
     In FIG. 7A, a blade lever 16 has a boss 16a rotatably mounted on a setting shaft 15. The blade lever 16 has an arm 16b and a hook 16c. A blade 17 serves to wipe the surface of the recording head at which the ink ejection outlets are formed. The blade is made of silicone rubber, chloroprene rubber or hydrogen containing nitrile butadiene rubber or another elastic material. A blade shaft 18 clamps at its central position the blade 17 in the manner that the blade 17 extends parallel to the shaft 15. The blade shaft 18 is rotatably mounted on the blade lever 16. A rotatable member 18a is formed integrally with the blade shaft 18. An ink carrier 19 is made of sintered plastic material, urethane foam material or the like, which is hydrophilic and porous and is fixed to the blade lever 16 at a position below the blade 17. The blade 17 and the ink carrier 19 are placed at such a position that they are overlapped with the cap 35 which will be described hereinafter, as seen from the head element 9a, so that they are actable on the head element 9a at the same position. The overlapping positional relation is advantageous because it can reduce the width of the apparatus in the scanning direction. 
     A setting lever 20 is rotatably mounted on the setting shaft 15. The set lever 20 is provided with stopping teeth 20a and 20b, a starting tooth 20c and a rotating tooth 20d. The starting tooth 20c has a thickness (measured in the longitudinal direction of the lead screw 2) which is approximately one half of the width of the other teeth. An arm 20e of the setting lever 20 is partly cut-away in the direction of its thickness, by which a setting surface 20f and a resetting surface 20g are provided. The surfaces 20f and 20g are effective to provide an accommodation for the rotating member 18a of the blade shaft 18 mounted to the blade lever 16, in which the blade 17 is movable between a projected position and a suspending position by the selective engagement of the rotatable member 18a with the surface 20f or the surface 20g. 
     A timing gear 21 is rotatably mounted on the base 20 by an unshown supporting member. 
     As shown in FIG. 7B, the timing gear 21 is provided with a stopping cam 21a for engagement with the stopping teeth 20a and 20b of the setting lever 20 described above, at a part of the periphery of the timing gear 21. It is further provided with three sets of driving teeth 21b1, 21b2 and 21b3 which are partly cut away. It is further provided with a capping cam 21c at a predetermined position to swing a capping lever which will be described hereinafter. Furthermore, it is provided with a piston setting cam 21f for urging a piston of a pump which will be described hereinafter. The piston setting cam 21f is in the form of a face cam. Also provided is a piston resetting cam 21g at a predetermined distance from and correspondingly to the piston resetting cam 21f. 
     A spring 22 functions to support an ink absorbing material 23 and is fixed to the base 50 at the position shown in FIG. 2, that is, at the position below the capping position by the cap 35. As shown in FIG. 7C, it has an absorbing material supporting portion 22a and a spring 22b for rotating the pump which will be described hereinafter. The ink absorbing material 23 is made of material which is hydrophilic and porous, similarly to the ink carrier 19. The ink absorbing material 23 has a cleaning portion 23a to which the blade 17 is contactable when it moves down. The lower portion of the ink absorbing material 23 is formed into an absorbing surface 23b to which the ink carrier 19 is contacted to transfer the ink. The absorbing material supporting portion of the supporting spring 22 is urged upwardly with small resilient force, so that it is locked at a predetermined position by an unshown stopper. Therefore, when the ink carrier 19 is contacted to the ink absorbing material 23, the ink absorbing material 23 displaces downwardly to flex the ink absorbing material spring 22 to secure the contact therebetween. 
     Referring to FIGS. 8 and 9 mainly, the description will be made as to a recovery system unit which is a part of the recovery system mechanism. In FIGS. 8 and 9, a cylinder 24 has a cylinder portion 24a and a guide portion 24b for guiding a piston shaft 27 which will be described hereinafter. The inner side of the guide portion 24b is partly cut-away in its longitudinal direction to provide an ink passage 24c for residual ink. A projection 24d functions to receive a cap lever and has a lever seal 33 engaged therewith. An ink passage 24e is opened at a predetermined position in the cylinder 24a. A rotating lever 24f is formed integral with the cylinder 24 and is urged in the rotational direction by the spring portion 22b of the ink absorbing member supporting spring 22. A residual ink pipe 24g is integrally formed with the cylinder 24, and an end thereof is cut into an acute angle, so that it can be easily inserted into residual ink absorbing material which will be described hereinafter. An ink passage 24h is formed in the residual ink pipe 24g. 
     A cylinder cap 25 is press-fitted into an end of the cylinder 24. A lever guide 25a is disposed at a position faced to the cap lever receiver 24d of the cylinder 24. 
     A piston seal 26 is inserted into the cylinder 24, and it has a smaller inside diameter to provide a predetermined contact pressure relative to the piston shaft which will be described below. The surface thereof may be coated with lubricating material to reduce the force required to slide the piston. 
     The piston shaft 27 has an operating shaft 27a, a piston confining collar 27b, a piston receptor 27c, a connecting rod 27d and a guide 27e. A groove 27f functioning as an ink passage is formed along the connecting rod 27d and the guide shaft 27e. A rotation stopper 27g is formed as a groove in the operating shaft 27a. A bearing 27h is provided at an end of the operating shaft 27a. 
     A piston 28 has a main portion as an inner layer as seen from the cylinder side, which is made of elastic and porous material. It may be a foam material (sponge or the like) having independent pores or a porous material having fine continuous pores. The porous material having the continuous pores such as urethane foam is preferable. It may be such that plural continuous pores exist in a direction crossing with the direction of elastic deformation. The outside diameter thereof is larger than the inside diameter of the cylinder 24 by a predetermined degree so that it is compressed to a proper extent when it is inserted into the cylinder 24. The foam material is so oriented that the solid (skin) layer of the material is at the outer periphery 28a and an end surface 28b contacted to the piston confining collar 27b of the piston shaft 27. Even if the material of the piston is of communicating foam type, the skin film does not allow the liquid communication, and therefore, the skin film provides the function of the piston. If the material without skin film is used, a coating layer may be provided. 
     Designated by a reference 42 is a pumping chamber. A piston pressing roller 29 is rotatably mounted at an end of the piston shaft 27. A piston resetting roller 30 is rotatably mounted at the end of the piston shaft 27. These rollers are supported on a pin 31. 
     A cap lever 32 has a rotational shaft 32a, an ink guide 32b and a lever guide 32c. At an end thereof, a sealing surface 32d which is spherical convex is provided. The cap lever 32 is provided with a vertical pair of engaging members 32e for engagement with pawls of the cap holder 34. An ink passage 32f extends from the sealing surface 32d, through the inside of the lever 32, deflected at 90 degrees, through the center of the ink guide 32b. The passage opens at the end thereof. At a lower position of the ink guide 32b, a cut-away portion 32g is formed. The cut-away portion 32g is effective to connect the ink passage 24e through the communicating hole 33a of the lever seal 33 to the inside of the cylinder 24a. 
     A lever seal 33 is mounted on the ink guide 32b and is press-fitted into the cap lever receptor 24d. A communication hole 33a provides liquid communication between the cut-away portion 32g of the ink guide 32b and the ink passage 24e. 
     A cap holder 34 is faced to a hook 34a for engagement with an engaging portion 32e of the cap lever 32. An opening 34b is for mounting the cap 35. 
     The cap 35 functions both to close the recording head so as to prevent the ink from drying and to seal the recording head when the ink is sucked therefrom. The cap 35 has a capping portion in which a sucking port 35b is formed, and therefore, opens toward the cap holder 34 through the center of the cap 35. 
     A flange 35c functions as a latch when mounted on the cap holder. The flange 35c has a cap seal 35d which is spherically concave to conform the sealing surface 32d of the cap lever 32. When it is urged to the cap lever 32, only the central port 32h communicates, and the other portion is sealed. Since the seal portions 32d and 35d are spherical, they are conformed to each other excellently. The recording head element 9a has a step on the ejection side surface, and even if so, the cap can accommodate the step to provide the stabilized sealing condition. 
     Referring back to FIG. 2, a sheet feeding roller 36 for conveying a recording medium such as paper or a sheet of paper, is provided. It can be produced by, for example, applying elastic paint (urethane resin or acrylic resin material) on the surface of a drawn aluminum pipe. The roller 36 functions as a platen for limiting the surface of the recording medium on which the recording is effected, by its outer surface, and also functions to accommodate the residual ink at the inside thereof. Residual ink absorbing material 37 is within the roller 36, and it comprises a thin pipe made of plastic material such as vinylchloride or the like and polyester fibers or another absorbing material to enhance the ink absorption in the longitudinal direction. Into the residual ink absorbing material 37, a residual ink pipe 24g of the cylinder 24 is inserted. Even if the recovery system mechanism movable by the movement of the base 50, the pipe 24g is supported in the absorber 37 in the manner that the movement is impeded. The fibers of the absorbing material are not liquid absorbing, such as resin or metal, but may be of slightly liquid absorbing nature. 
     A sheet confining plate 38 is made of fluorinated resin or a material to which carbon fibers are mixed, for example. As shown in FIG. 3, it is divided into four portions, which are mounted on the base frame 1. A shaft 38A is provided to release the confining force of the confining plate 38. To an end of the shaft 38A, a gear 38B is fixed, and the other end thereof is engaged with a bearing 38C for supporting the shaft 38A. The bearing 38C is fixed on the base frame 1. The gear 38B is meshed with a gear of a release lever, which is not shown. A sheet feeding motor 39 is coupled with the sheet feeding roller 36 through a reduction mechanism having a predetermined reduction ratio. 
     Designated by a reference numeral 40 is a recording medium such as paper or film. 
     The operation will be described. 
     In normal recording operation, the rotation of the shaft of the carrier motor 11 rotates the lead screw 2 through the timing belt. Then, the carrier 6 moves in the scanning direction through the engagement between the lead groove 2a and the lead pin 7. Since the carrier motor 11 is urged by the motor spring 14, the timing belt is always stretched, to provide good drive transmission. 
     The inertia exists upon movement of carrier 6, upon start and upon termination, but the weight of the motor 11 absorbs the inertia, so that the force applied to the motor spring 14 is small. The load on the motor is also small. If an air damper or an oil cylinder is used in association with the motor spring 14, the noise attributable to the vibration of the rotor of the motor can be reduced upon the start and stop of the carrier. By properly selecting the weights of the motor and the carrier and the damper coefficient, the overshooting of the motor can be reduced, so that the noise can be reduced. 
     Referring to FIGS. 10 and 16, the operation of the apparatus when the apparatus is not performing the recording operation is described. 
     FIG. 10 is a timing chart, wherein it will be understood that the operational timing of various parts can be determined on the basis of the number of pulses supplied to the motor. 
     FIG. 11 is a perspective view showing the structure of the clutch gear 4 and the timing gear 21. The key groove 4d of the clutch gear 4 is engaged with the key 2h of the lead screw 2, by which the clutch gear is slidable on the lead screw, while it is rotatable together with the lead screw 2. The clutch gear 4 is urged by the spring 5 toward the carrier 6, so that during the recording operation, it is at a predetermined position along the groove 2i of the lead screw 2 and rotates together with the lead screw 2. When the recording head 9 moves to the home position, the clutch gear 4 is urged by the carrier 6 to be engaged with the timing gear 21. 
     The clutch gear 4 has a starting tooth 4c1 and driving teeth 4c2 which are formed at different positions of the clutch gear in the direction of the width thereof. In addition, the driving teeth 4c2 are not formed uniformly over the entire circumferential periphery, has a curved surface position 4b at a part thereof. The clutch gear 4 has a flange 4a along the entire circumferential periphery thereof. 
     The timing gear 21, as has been described in conjunction with FIG. 7B, is provided with the starting teeth 21b1 and two different driving teeth 21b2 and 21b3. The teeth 21b1, 21b2 and 21b3 are formed at different positions of the gear 21 in the direction of the width thereof. 
     FIGS. 12A, 12B and 12C and FIGS. 13A and 13B show various states of engagement between the clutch gear 4 and the timing gear 21. FIGS. 12A and 12B show the states which is assumed during the normal recording operation. In the state of FIG. 13A, the lead pin 7 is not at this position, though. Above the ink absorber 23, the blade 17 and ink carrier 19 are disposed, although not shown in the Figure. 
     At this time, the clutch gear 4 rotates together with the rotation of the lead screw 2. Since, however, the starting tooth 4c1 and the starting tooth 21b1 are out of engageable positional relation (FIG. 13A), the timing gear 21 does not rotate. In addition, since the driving teeth 21b2 at the left end of the timing gear 21 and the flange 21h are at the engageable (interferable) positions with a small clearance from the flange 4a, the timing gear 21 is prevented from rotation in any direction. 
     Therefore, the timing gear 21 does not rotate unintentionally even if an erroneous manual force is applied or an unexpected rotational force is applied to the timing gear 21. Thus, the operating position of the recovery system is prevented from deviation. 
     When the recording head 9 is moved toward the home position to such an extent that the carrier 6 urges the clutch gear 4, the positional relation between the clutch gear 4 and the timing gear 21 becomes finally as shown in FIG. 13B. During the process, the engageable positional relation is established between the starting tooth 4c1 and the starting tooth 21b1 (at this time, however, the lead pin 7 is not yet at this position). 
     Then, with the movement of the lead pin 7 of the carriage 6 from the groove 3c to the groove 3b of the lead screw 2 (FIG. 2), the clutch gear 4 rotates in the clockwise direction in FIG. 12A, by which the positional relation changes from the state shown in FIG. 12A to the state shown in FIG. 12C. Until the starting tooth 4c1 is engaged with the starting tooth 21b1, the timing gear does not move unintentionally to engage first the other teeth, since the curved surface portion 4b (non-engaging portion) shown in FIG. 11 is closest to the timing gear 21. 
     Therefore, the engagement between the clutch gear 4 and the timing gear 21 always starts by the engagement between the starting teeth thereof, so that the rotation of the timing gear 21 starts from the correct position at all times. 
     This assures the correct operation of the recovery system driven through the timing gear 21. 
     An additional advantage is that the mounting positional accuracies of the clutch gear 4 and the timing gear 21 are not required to be very high. 
     The driving tooth 21b3 of the timing gear 21 provided at the different position shown in FIG. 7B is brought into engagement when the curved surface portion 4b is contacted again to the timing gear 21. If these driving teeth are at the same position as the driving gear 21b2, they are contacted to the curved portion 4b. Therefore, the driving teeth are engaged at the deviated position. 
     As long as the timing gear 21 is rotated by the engagement of the driving teeth, the hook 6c of the carrier 6 slides on the surface of the timing gear 21 opposite from the recording region. 
     By doing so, the recording head 9 is prevented from aparting from the home position (it may occur when the lead pin 7 is away from the groove 3b before the engagement between the predetermined teeth, for example). This is because the lead screw 2 rotates during the recovery processing operation with the recording head 9 at the home position, so that the lead pin 7 can move to the groove 3c. 
     In the foregoing embodiment, the recovery operation is effected by two rotations of the lead screw, but this is not limiting, and the degree of the rotation may be properly selected by one skilled in the art. Thus, the latitude in the design of the clutch mechanism or the like can be increased. 
     Referring to FIGS. 14A, 14B, 14C, 14D, 15A, 15B, 15C, 16A and 16B, and also referring to FIGS. 12A, 12B, 12C, 13A and 13B, the operation will be described. FIGS. 14A, 14B, 14C and 14D illustrate various operational states of the mechanism including the blade 17 or the like; FIGS. 15A, 15B and 15C illustrate sequential operational states of the mechanism including the cap 35; and FIGS. 16A and 16B illustrate operation of a mechanism for introducing the residual ink into a residual ink container 37 within the roller 36. 
     First, the carrier 6 moves to the home position in the direction indicated by an arrow B. At this time, as shown in FIG. 13A, the lead pin 7 is engaged with the lead groove 2a, and the ejection outlets 9c of the head element 9a are at a position facing to the ink carrier 19 (FIG. 14A). At this position, all of the energy generating elements of the head element 9a for producing the energy contributable to ejecting the ink are driven to eject the ink therethrough (preliminary ejection) by which the ink having a slightly increased viscosity or the like is ejected. Then, the recovery operation using the preliminary ejection is terminated. Also, the preliminary ejection may be effected at this position periodically in order to prevent the viscosity of the ink from increasing adjacent such ejection outlets as are not used in the normal recording operation. FIG. 14A is a side view at this position. 
     As shown in FIG. 13B, when the rotation of the lead screw 2 moves the carrier 6 in the direction B, the clutch gear 4 is pushed by the urging portion 6a, so that the clutch gear 4 is moved in the same direction (B) to shift the start tooth 4c1 to a position for engagement with the start tooth 21b1 of the timing gear 21. Thereafter, the clutch gear 4 rotates in synchronism with the lead screw 2, by which the start teeth are engaged with each other, so that the timing gear 21 rotates in the direction D, as shown in FIG. 14B. On the other hand, the lead pin 7 is in the positioning groove 3b from the introduction groove 3c, and therefore, the carrier 6 does not move even if the lead screw 2 rotates. 
     When the timing gear 21 rotates in the direction B, the setting lever 20 starts to rotate in a direction E, since the gear of the timing gear 21 is meshed with the gear of the set lever 20. Until this point of time, the blade lever 16 has not been moved since the hook 16c of the blade lever 16 is engaged with a pawl of the base frame, and only the set lever 20 rotates. Sooner or later, the setting surface 20f of the setting lever 20 rotates in a direction F, while pushing down the rotatable member 18a of the blade shaft 18, and therefore, the blade 17 rotates in a direction G to be set into a state engageable to the ejection side surface. 
     When the timing gear 21 further rotates in the direction D, the hook 16c of the blade lever 16 is released from the pawl of the base frame 1, and the setting lever 20 and the blade lever 16 also rotate further. As shown in FIG. 14C, the blade 17 wipes the ejection side surface of the recording head element 9. The residual ink or the like removed by the blade 17 is directed only in one direction, that is, downwardly, in this embodiment. The ink liquid or the like thus removed is absorbed by or retained on the top portion of the ink carrier 19. At this time, the ink carrier 19 begins to contact the ink absorber 23. When the setting lever 20 rotates further, the ink carrier 19 and the blade 17 slide on the surface of the cleaner 23a of the ink absorber 23, by which the ink received by the ink carrier 19 during the preliminary ejection, the foreign matter removed by the blade 17 from the ejection outlet side surface or the like are received by the cleaner 23a, and in addition, the droplets of ink deposited on the ejection side surface can be absorbed. Accordingly, the ink absorbing power of the ink carrier 19 can be maintained for a long period of time. 
     The timing gear 21 rotates further in the direction D. Since, however, the stopping teeth 20a and 20b of the setting lever 20 are faced to and contacted to the stop cam 21a of the timing gear 21, the rotation of the setting lever 20 is stopped, and simultaneously, the driving teeth absent portion of the timing gear 21 is presented, and therefore, the rotating drive is not applied. 
     As described, since the absorber for retaining the ink or the like removed by the blade also functions as an ink receptor for the preliminary ejection, the size of the apparatus can be reduced, and also, the time required for the recovery operation can be reduced. 
     The timing gear 21 further rotates. Since the cap cam 21c of the timing gear 21 controls the rotational shaft 32a of the cap lever 32c shown in FIG. 8, at the initial stage, the cap 35 is at rest at a position away from the ejection side surface of the head element 9a, as shown in FIG. 15A. When the timing gear 21 further rotates in the direction D, the cap cam 21c is released, so that, as shown in FIG. 15B, the rotating lever 24f of the cylinder 24 is urged by the spring 22b of the ink absorbing spring 22. This rotates the cylinder 24 in the direction F. Then, the capping portion 35a of the cap 35 is brought into press-contact with the ejection side surface, thus accomplishing the capping operation. As will be understood, the capping portion 35a is brought into contact to the ejection side surface gradually from the bottom portion. By doing so, the air in the space between the capping portion 35a and the ejection side surface can be pushed out without pushing back the meniscus of the ink in the ink ejection passages of the recording head. FIG. 13B is a top plan view in this state. As will be understood, the urging force by the cap closely contacts the sealing surface 32d to the cap seal portion 35d. 
     The foregoing is the cleaning and capping operation for the ejection side surface. Normally, the operation stops here, and in response to the subsequent production of the recording signal, the reverse operation is performed, and then the recording operation is started. 
     Now, the description will be made as to a sucking recovery operation which is performed when satisfactory ejection is not accomplished even by the preliminary ejection. 
     When this is started, the timing gear 21 is further rotated from the capping position, by which the cap lever 32 is urged by the cap cam 21f to displace the cap 35 slightly away from the ejection side surface, as shown in FIG. 15C. 
     When the timing gear 21 rotates further in the direction D, it is released from the cap cam 21f, again, so that the capping portion 35a is press-contacted to the ejection side surface. 
     The pumping action will be described. When the recovery operation is started after the completion of the capping operation, the sucking operation is started. 
     The rotation of the timing gear 21 causes the piston setting cam 21g to push the piston urging roller 29 mounted on the piston shaft 27, by which the piston shaft 27 moves in a direction H, as shown in FIG. 16A. The piston 28 is pushed by the piston confining collar 27b and is moved in the direction H. Then, the groove 27f is closed, so that a level of vacuum is established in the pumping chamber 42. Since a skin layer is provided at the outer periphery of the piston 28 and at the contact surface with the piston confining collar 27b, the ink is prevented from leaking through the continuous pores of the foam material. 
     Since the ink passage 24e of the cylinder 24 is closed by the piston 28, the piston 28 is movable only to increase the vacuum of the pumping chamber 42. On the other hand, after the recapping operation described above, the ink passage 24e is opened, as shown in FIG. 16A, so that the ink is sucked from the head 9 through the sucking port 35b of the cap 35. The sucked ink flows through the ink passage 32f formed within the cap lever 32, the communicating hole of the lever seal 33 and through the ink passage 24e of the cylinder 24 into the pumping chamber 42. 
     With the continued rotation of the timing gear 21, the cap 35 is again slightly moved away from the ejection side surface of the recording head by the cap cam 21h, upon which the ink is sucked from the ejection side surface and from the inside of the cap 35a by the vacuum remaining in the pumping chamber 42 to remove the residual ink from these portions. 
     Then, the timing gear 21 is rotated in the reverse direction (opposite from the direction shown by the arrow in FIG. 14D), the piston resetting cam 21i pulls the piston resetting roller 30, by which, as shown in FIG. 16B, the piston shaft 27 is moved in a direction indicated by an arrow J. When this occurs, since the piston 28 moves only after it is contacted to the piston receiving portion 27c of the piston shaft 27, a clearance Δl is provided between an end surface 28b of the piston 28 and the piston confining collar 27b. Then, by the movement of the piston shaft 27 and the piston 28, the residual ink absorbed in the pumping chamber 42 is discharged to the neighborhood of a center of the residual ink absorbing material 37 through the above-described clearance Δl, the groove 27f of the piston shaft 27, the ink passage 24c of the cylinder 24, and the ink passage 24h of the residual ink tube 24b. Here, the ink passage 24e of the cylinder 24 is closed by the piston 28 at the initial stage of the piston 28 operation, and therefore, the residual ink does not flow reversely toward the cap 35. 
     FIG. 17 shows in summary the sequential operations for the preliminary ejection and the sucking recovery. However, the shown sequence is for the case in which the blade 17 is awaited in the operable state (setting state shown in FIG. 14B); then, the blade 17 becomes inclined with respect to the absorber 23 after the wiping operation (reset state shown in FIG. 14A); and thereafter, the blade 17 is set to the operative position immediately before the setting lever 20 restores its original position. 
     Referring to FIGS. 3A and 3B, the description will be made as to the recording medium feeding mechanism from the recording operation to the sheet discharge operation. 
     In these Figures, the sheet confining plate is made of fluorinated resin or a material in which carbon fibers are mixed. It urges the supplied recording sheet or paper to maintain a predetermined gap between the recording sheet and the ejection side surface of the recording head 9. The confining force of the sheet confining plates 38 is provided by the spring 38D. FIGS. 18A and 18B show details of the mechanism. 
     In FIG. 18A, the sheet confining plates 38 apply the confining force to the sheet feeding roller. A shaft 38A has a &#34;D&#34; shape (a part of its circumference is cutaway into a straight surface) and is in slidable relation with the sheet confining plates 38 in the rotational direction. In the state of this Figure, the straight portion of the shaft 38A is at such a position that it is contacted to the end 38F of the spring plate 38D. Therefore, the end 38E of the plate 38D is urged upwardly by the spring plate 38D. Accordingly, the confining plate 38 is urged to rotate in the clockwise direction about an axis of the shaft 38A to apply the confining force to the sheet feeding roller 36. 
     On the other hand, FIG. 18B shows the state wherein the urging force by the sheet confining plate 38 is released. When the shaft 38A rotates so that the arcuate portion of the shaft urges the end 38F, the spring plate 38D is entirely urged downwardly, and therefore, the end 38E is not urged by the spring plate 38D. 
     In this released state, the shaft 38A and the sheet confining plate 38 are engaged with each other with a certain degree of friction, so that the sheet confining plate 38 is prevented from changing the rotational position to a large extent. Therefore, even when the necessity occurs to release the urging by the sheet confining plate 38, the movement of the recording head or the like is not obstructed by the sheet confining plate 38. 
     The sheet confining mechanism described above is capable of providing such urging force as not to prevent the proper conveyance of the recording sheet by the sheet feeding roller 36 within a limited space. 
     More particularly, the sheet confining plates themselves are not made of elastic material, and the urging force is provided by the leaf springs disposed on the bottom base frame 1 which is usually an empty space, and therefore, the latitude for the urging force adjustment accomplished by the adjustment of the length of the leaf spring is increased. In addition, the size of the sheet confining members can be reduced. 
     The leaf spring 38D is mounted on the base frame 1 by an unshown mounting member. 
     Referring back to FIGS. 3A and 3B, a sheet discharging roller functions to discharge the recording sheet having been subjected to the recording operation. Rowels 61 function to confine the recording sheet conveyed by the discharging roller 60 to confine the sheet discharge direction of the recording sheet and to provide conveying force therefor. 
     A transmission roller 62 is disposed between the sheet discharging roller 60 and the sheet feeding roller 36 to transmit the rotation of the sheet feeding roller 36 to the sheet discharging roller 60. The transmission of the rotation is effected by the friction force provided by the contact therebetween. The sheet discharging roller 60 is generally cylindrical, but the diameter at the opposite end portions thereof is different from that at the central portion. The transmission roller is contacted to the central portion of the discharging roller 60 which has the smaller diameter. Therefore, the opposite end portions having the large diameter and functioning to convey the recording sheet rotates at a larger peripheral speed than that of the sheet conveying roller 36. Thus, when the sheet is discharged, the recording sheet is slightly stretched, so that the recording surface can be maintained in good order. 
     The rotational shafts of the transmission roller 62 and the rowels 61 are made of coil spring having a proper elasticity coefficient. The mechanism will be described in detail, taking the rowel 61 as an example, referring to FIG. 19. 
     In FIG. 19, a shaft 61A is made of coil spring extending through the center of the rowels 61 at the opposite sides thereof, and is rotatably engaged with the rowels 61. Bearings 103B support opposite ends of shaft 61A, and are formed as a part of the inner cover 103 shown in FIG. 1. The bearings 103B support the shaft 61A for sliding movement in the longitudinal direction. Limiting members 103C limit movement of the rowel 61 in the direction of the rotational axis and in the direction perpendicular thereto. They are disposed at opposite sides of the rowel 61, and are formed as a part of the inner cover 103. 
     By the structure described above, the shaft 61A supports the rowels 61, and simultaneously, provides an urging force of the rowels 61 to the discharging rollers 60 by its resilient force. 
     The inner cover 103 has a spring 103A formed at the rear end thereof, as shown in FIG. 3A to receive an urging force toward the sheet discharging roller by reaction force from the case 101. By the cooperation between the urging force and the resilient force of the rotational shaft 61A, the rowels 61 provide proper urging force to the sheet discharging rollers 60. 
     Since the inner cover 103 receives the urging force, the engagement is assured between the fixing member 103D of the inner cover 103 and the rotational shaft 60C of the discharging rollers 60, as shown in FIG. 3A. As a result, the positional relation between the rowels 61 and the discharging roller 60 are maintained constant at all times. Alternatively, by abutting and fixing the rotational shaft 60C to a locking member or the like, the highly accurate relation can be maintained irrespective of the accuracy of the inner cover. 
     The function of the rotation shaft 62A made of coil spring is the same as in the transmission roller 62. More particularly, by the resilient force of the shaft 62A, the contact pressure to the sheet feeding roller 36 and the sheet discharging roller 60 is provided. 
     As described in the foregoing, the discharging roller 60 has a smaller diameter in the longitudinal central portion than in the opposite portions. This will be described in detail in conjunction with FIG. 20. 
     In FIG. 20, a cover member 60A is made of rubber material. A core member 60D is cylindrical, but the diameter at its opposite ends is larger than that at the center. The sheet discharging roller 60 is produced by covering the core member 60D with a cylindrical cover member 60A. 
     Therefore, it is not necessary to integrally form rubber material or the like into the shape, and therefore, the sheet discharging roller can be produced relatively easily and at lower cost. 
     A groove 60B continuously formed adjacent an end of the sheet discharging roller 60 is effective to lock an end portion of the recording sheet when the recording sheet is discharged by the discharging roller 60, so that the sheet discharging operation is assured even when the position of the recording sheet is deviated. 
     The configuration of the core member 60D is not limited to that described above. For example, it may be an extension of grooves 60B having a smaller central portion, if it is formed into a cylinder by covering it with rubber material. 
     Referring to FIGS. 21 and 22, the description will be made as to the case in which the ink jet recording apparatus of this embodiment is vertically placed and operated. 
     When the apparatus is placed vertically, it can be used with an automatic cut sheet feeder 200 or can be used with a thick material such as an envelope supplied through a supply inlet at the backside of the apparatus. 
     When the normal recording sheets usable with the automatic feeder are used, the top cover 102 can be used as a stacking tray for the recording sheets. In this case, the top cover 102 is fixed at an angle which is different from the angle when the top cover 102 is used as a sheet guide for the supply sheet. 
     The use of the top cover 102 as the stacker will be considered. 
     The top cover 102 is situated in such a manner that the discharged recording sheet is conveyed in the air to a certain extent due to the rigidity thereof and is first contacted to the top cover 102 or the top of the stacked sheets, adjacent a top end 102A of the top cover 102. By doing so, the sheet being discharged slides on the topmost of the already stacked sheets only within a limited range, that is, in the neighborhood of the leading edge of the recording sheet. This minimizes the sliding movement of the recording sheet, so that the contamination of the recording sheet by the insufficiently fixed ink can be prevented. 
     To accomplish this, in this embodiment, the top end portion 102A is placed adjacent to the sheet discharging line, that is adjacent to the common tangent line between the sheet feeding roller 36 and the sheet discharging roller 60, and in addition, the bottom end portion 102B is lower than the top end portion 102A. 
     Additionally, the arrangement is such that when the trailing edge of the recording sheet stopped on the top end portion 102A is completely discharged, the sheet falls at the position without sliding on the stack. 
     To accomplish this, the length of the top cover 102 measured in the sheet discharge direction, that is, the length from the top end 102A to the bottom end 102B, is important. Where the recording sheet is a usual sheet, and where the sheet is discharged substantially horizontally, the length is 60-90%, preferably 70-80% of the length of the recording sheet. 
     If the structure of the recording apparatus is different, if the using conditions are different, or if the sheet discharging direction is different, the length of the stacking tray is determined in consideration of the above by one skilled in the art. 
     In FIGS. 21 and 22, designated by a reference numeral 108 is a tongue for preventing the stacked recording sheets from being introduced into the sheet feeding inlet 106. 
     Referring to FIGS. 23-28, the recording head 9 and the carrier 6 will be described in detail. 
     FIG. 23 is a perspective view showing an outer appearance of the recording head 9 comprising as a unit an ejection element 9a and an ink container 9b. A pawl 906e is engaged with a hook of a carrier when the recording head 9 is mounted on the carrier 6. As will be understood from the Figure, the pawl 906e is located within the longest length of the recording head. Adjacent the ejection element 9a at the front side of the recording head 9, an abutment positioning portion is provided, although not shown in this Figure. An opening 906f is formed in the head for receiving a supporting plate which is projected from the carrier 6 to support a flexible substrate and a rubber pad. 
     FIGS. 24A and 24B are an exploded perspective and an outer appearance perspective view of the ink Jet recording head shown in FIG. 23. As described in the foregoing, it is a disposable type recording head having an integral ink container (ink supply source). 
     In FIG. 24A, designated by a reference numeral 110 is a heater board having a Si substrate, electrothermal transducer elements (ejection heaters) and aluminum or the like lead lines for supplying electric power thereto, wherein the transducer elements and the lead lines are produced by a thin film process. The heater board 110 is electrically connected with a wiring board 210, and the corresponding lines are connected by wire bonding. 
     The recording head is provided with a top plate 400 having partition walls for defining ink passages and an ink chamber. In this embodiment, the top plate 400 is made of resin material having an integral orifice plate. 
     A supporting member 300 made of metal and a confining spring 500 are engaged with each other with the heater board 110 and the top plate 400 sandwiched therebetween, so that the heater board 100 and the top plate 400 are clamped by the urging force provided by the confining spring 500. To the supporting member 300, the wiring board 210 may be bonded, and the supporting member 300 may provide a positioning reference relative to the carrier 6. The supporting member 300 also functions as an element for irradiating the heat of the heater board 100 resulting from the driving of the electrothermal transducer. An ink supply chamber 600 receives ink from the ink container 9b (ink supply source), and functions as a subordinate container for supplying ink to the common chamber defined by bonding the top plate 400 to the heater board 110. A filter 700 is disposed in the supply chamber 600 adjacent the ink supply port to the common chamber. The supply chamber 600 is covered by a cover 800. 
     The ink container 9b contains an ink absorbing material 900. An ink supply port 1200 supplies ink to the ejection unit 9a, having the various parts 110-800. Before the ejection unit 9a is mounted to the portion 1010 of the ink container 9b, the ink is injected through the supply port 1200, by which the ink is absorbed by the absorbing material 900. 
     The cartridge has a cover 1100 which is provided with a hole 1301 for providing communication between the inside of the cartridge and the atmosphere. In the hole 1301, there is water repellent material, by which the ink is prevented from leaking through the hole 1301. 
     When the ink is filled in the ink container 9b through the supply port 1200, the ejection unit 9a comprising various elements 110-800 is positioned relative to the portion 1010. The correct positioning therebetween is accomplished by the projections 1012 of the ink container 9b and the corresponding openings 312 formed in the supporting member 300. Thus, the recording head 9 in the form of a cartridge as shown in FIG. 24b is manufactured. 
     The ink is supplied to the supply chamber 600 from the inside of the cartridge through a supply port 1200, a hole 320 of the supporting member 300 and an inlet opening of the supply container 600 at the backside in FIG. 24A. From the supply chamber 600, the ink is supplied into the common chamber through a supply pipe and an ink inlet 420 of the top plate 400. In the connecting portions in the ink supply line, a suitable gasket made of silicone rubber or butyl rubber or the like is mounted for the sealing to assure the ink supply. 
     FIGS. 25A, 25B and 25C are a top plan view, a left side view and right side view of the carrier 6. 
     A supporting plate 606 is projected from the bottom of the carrier 6. It supports a flexible substrate 604, and a rubber pad 605 which has projections 605A corresponding to contact pads formed on the substrate 604. 
     An abutment member 607 is projected from the bottom of the carrier 6 adjacent its front end. The thickness of the abutment member 607 is desirably as small as possible in order to provide maximum volume for the ink container within the limited space on the carrier 6. Therefore, the member 607 has three ribs 608 to provide mechanical strength thereof. The ribs 608 extend in a direction of carrier 6 movement to provide a strength against the rotational direction upon the mounting or dismounting of the recording head relative to the carrier 6. In addition, each rib 608 has a dimension such that it is approximately 0.1 mm beyond the ejection side surface when the recording head 9 is mounted. By doing so, the recording sheet is prevented from rubbing the ejection side surface, and therefore, from damaging the ejection side surface, even if the recording sheet is present in the recording head moving path for some reason or another. 
     A contact lever 602 is operated when the recording head is mounted on or dismounted from the carrier 6. It is rotatably supported on a shaft 601d of the carrier 6. A contact hook 603 is partly contactable to the recording head 9 for the mounting and dismounting of the recording head 9 by operation in engagement with a part of the contact lever 602. The hook 603 has an elongated slot 603c which is guided by a guide pin 601c mounted on the carrier 6 in the mounting and dismounting operation. 
     The mounting and dismounting mechanism including the contact lever 602, the contact hook 603 or the like is disposed at a side of the carrier 6, that is, at a side in the carrier 6 movement direction, and therefore, the mechanism does not require a large dead space to permit movement of the carrier. 
     The description will be made as to the abutment portions for the positioning of the recording head. The abutment portions 601A are effective to the positioning in the left-right direction, and two of them are at a side of the abutment member 607. As for the left-right direction positioning, an abutment portion 601f on the supporting plate 606 is used in addition to the abutment portions 601a. 
     An abutment portion 601b is formed at a side and bottom portion of the abutment member 607 to position the recording head in a front-rear direction. 
     The abutment portions 601c are for the positioning in the vertical direction, and two of them are formed at a side and bottom of the abutment member 607 and at a side bottom portion of the supporting plate, respectively. 
     FIGS. 26A and 26B are top plan view and a side view when the recording head 9 is mounted on the carrier 6. 
     An abutment portion 906a is formed on the recording head 9 for the abutment to the carrier 6, and the abutment portions 906b and 906c corresponds to the abutment portions 601b and 601c, respectively. 
     Referring to FIG. 26A, the engagements in the various portions will be described when the recording head is mounted on the carrier. 
     The abutment portion 906a of the recording head 9 abuts the abutment portion 601a of the carrier 6, and simultaneously, the pawl 906e of the recording head 9 is urged toward left in the Figure by the urging force of the coil spring 607a through the hook 603 engaged therewith. Thus, the recording head 9 receives a moment about the abutment portion. At this time, the substrate 906d of the recording head is abutted to the abutment portion 601f, by which the recording head 9 is correctly positioned in the left-right direction, and the position is retained. 
     Also, at this time, the projections 605A of the rubber pad 605 are compressed and deformed by the abutment with the substrate 906d. By the deformation, press-contact force is produced between the contact pads of the flexible substrate 604 and the contacts of the board 906d . In this case, since the substrate 906d is contacted to the abutment portions 601f, the amount of deformation of the projections 605A is constant, so that the press-contact force is stable. 
     In the Figure, the compressed and deformed state of the projections 605A is not shown. 
     As will be described hereinafter, the positioning of the recording head 9 in the front-rear direction and the vertical direction has already been accomplished during the mounting process. 
     FIG. 27 is a top plan view of the carrier 6 before the recording head is mounted, the contact lever 602 being omitted in this Figure for sake of simplicity. 
     In the state shown in this Figure, the contact lever 602 is retracted (toward rear) (FIG. 25B), and at this time, the position of the contact hook is as shown in FIG. 27. The carrier waits for the recording head 9 to be mounted with this position. 
     FIGS. 28A, 28B and 28C are top plan views showing the process of the recording head being mounted. The recording head 9 is moved close to the carrier 6 from above the carrier 6 so that the opening 906f receives the supporting plate 606. At this time, as shown in FIG. 28A, the recording head 9 is mounted on the carrier 6 with inclination because of the positional relationship among the abutment member 607, the supporting plate 606 and the contact hook 603 and because of the relation between the total length of the recording head 9 and the opening 906f. 
     When the contact lever 602 is rotated in the counterclockwise direction (FIG. 25D), the contact hook 603 rotates in the counterclockwise direction about the shaft 601c, and thereafter, when it becomes horizontal, it moves toward left into the state shown in FIG. 28B. 
     In compliance with this movement of the contact hook 603, the recording head 9 is urged in the upper left part in this Figure by the engagement with the contact hook 603. Then, the abutment portion 906a of the recording head slides to become on the abutment portion 601a, and the contact portion 906b is abutted to the abutment portion 601b. In this state, the substrate 906d and the flexible substrate 604 are not contacted. 
     With the further counterclockwise rotation of the contact lever 602, the contact hook 603 is moved further leftwardly. During this, it moves the engaging pawl 906c, and therefore, the recording head 9 rotates in the clockwise direction about the abutment between the abutment portions 906a and 906b into the state shown in FIG. 28C, by which the position of the recording head 9 on the carrier 6 is determined. 
     The front-rear and vertical positions are determined during the process of the mounting. 
     In the state shown in FIG. 28C, the contact lever 602 is urged toward left by the coil spring 607a in the inside of the rotational shaft, as described hereinbefore, and the urging force is effective to fix the recording head 9 onto the carrier 6 through the contact hook 603. 
     As will be understood from the foregoing, the mounting of the recording head in this embodiment includes a translational movement and a rotational movement of the recording head, and the angle of rotation is approximately 5 degrees. 
     Since the recording head is mounted with the small rotational angle, no particular space is required for the mounting of the recording head. 
     Referring to FIGS. 25A and 26A, the relationship will be described between the contact lever and the contact hook. 
     As shown in these Figures, the contact lever 602 is provided with two flat surfaces 602a and 602b and a single slanted surface (cam surface) 602c. When the recording head 9 is fixed (FIG. 28C), the surface 602A is engaged to a portion 603a of the contact hook 603 to apply an urging force to the hook 603. 
     The relationship between the lever 602 and the hook 603 during the recording head dismounting process will be described. The contact lever 602 is rotated from the state shown in FIG. 26A in a direction opposite from that in the mounting process, the cam surface 602c of the contact lever rotates in contact with the cam surface 603b of the contact hook. Then, the contact hook 603 moves toward the right until the left end of the elongate slot 603c abuts the shaft 601c of the carrier 6. Thereafter, it rotates in the clockwise direction about the shaft 601c. When the abutment surface of the contact lever 602 reaches the flat surface 602b, it abuts an end of the cam surface 603b of the contact hook 103, so that the state shown in FIG. 25A is reached. 
     In the process from the state of FIG. 26A to the state of FIG. 25A, the recording head 9 is pushed out by the portion 603d of the contact hook. 
     The present invention is particularly suitable for use with a bubble jet recording head and a bubble jet recording apparatus proposed by Canon Kabushiki Kaisha, Japan. 
     Preferably, the recording head and the apparatus is of the type disclosed in U.S. Pat. Nos. 4,723,129 and 4,740,796 which disclose a typical structure and the operational principle. The structure and the principle are applicable to a so-called on-demand type recording system and a so-called continuous type recording system. Particularly, however, the bubble jet structure and principle are suitable for the on-demand type because the principle is, in brief, such that at least one driving signal is applied to an electrothermal transducer disposed on a liquid (ink) retaining sheet or 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 to produce the film boiling at the heating portion of the recording head, upon which a bubble can be formed in response to the driving signal. By the development and contraction of the bubble, the liquid 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 occur instantaneously, and therefore, the liquid is ejected with quick response. The driving signal in the form of a 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 as disclosed in U.S. Pat. No. 4,313,124. 
     The structure of the recording head may comprise the combination of the ejection outlet, the liquid passage and the electrothermal transducer as disclosed in the above mentioned U.S. Patents (linear liquid passage or rectangular liquid passage), or may be the one disclosed in U.S. Pat. Nos. 4,558,333 and 4,459,600 wherein the heating portion is disposed at a bent portion. The present invention is also applicable to the structure disclosed in Japanese Laid-Open Patent Application No. 123670/1984 wherein a common slit is used as the ejection outlets for plural electrothermal transducers, and also to the structure disclosed in Japanese Laid-Open Patent Application No. 138 461/1984 wherein an opening for absorbing pressure wave of the thermal energy is formed corresponding to the ejecting portion. 
     The present invention is effectively applicable to a so-called full-line type recording head having a length covering the maximum recording width. Such a recording head may comprise a long single recording head or plural recording heads combined to cover the entire width. 
     The present invention is also effectively applicable to a recording head in the form of an exchangeable chip which is electrically connected with and supplied with ink from the main assembly of the recording apparatus when mounted on the main assembly, or in the form of a cartridge type recording head integrally mounted. 
     The provision of the recovery means or the auxiliary means for the preliminary operation is preferable, because it can further stabilize the advantageous effects of the present invention. As for examples of such means, there are capping means for capping the recording head, cleaning means for cleaning the recording head, pressure applying means or sucking means for applying pressure to or sucking the liquid in the passage, preliminary heating means using the ejecting electrothermal transducers or by a combination of the ejecting thermal transducer and additional heating means, and means for effecting preliminary ejection of the liquid not for the recording operation. These recovery means can stabilize the recording operation. 
     As regards the recording mode of the recording apparatus, it is not limited to the record only by a main color such as black. The present invention is effectively applicable to a recording apparatus having an integral recording head or a combination of plural recording heads for the recording operation at least one of the multi-color mode using different colors and a full-color mode using color mixture. 
     In the foregoing embodiment, the ink has been described as liquid. However, it may be an ink material which is solid at the room temperature or an ink material which is softened at the room temperature. Since in the ink jet recording system, the ink is usually controlled within the temperature not lower than 30 ° C. and not higher than 70 ° C. to stabilize the viscosity of the ink to stabilize the ejection, the ink may be such that it is liquid when the recording signal is applied in use. The present invention is applicable to the ink which is liquefied by application of the thermal energy thereto. In an example of such a type, the thermal energy is positively consumed for the phase change from the solid state to the liquid state so as to suppress the temperature rise by the thermal energy. In another example, ink is provided which is solidified when left as it is, for the purpose of preventing the evaporation. In these examples, the ink is liquefied by the application of the thermal energy thereto in response to the recording signal, and the liquefied ink is ejected. In one example, the ink already starts to be solidified when reaching the recording medium. Such an ink material may be retained as liquid or solid ink in holes or recesses formed in a porous sheet as disclosed in Japanese Laid-Open Patent Application Nos. 56847/1989 and 71260/1985. In this case, the sheet is faces to the electrothermal transducers. 
     The most effective actuation of the above-described ink is to cause film boiling thereof. 
     As will be understood from the foregoing, according to the present invention, the sheet confining member for directly pressing the platen, and the means for providing the urging force, are separate means. In addition, the urging force producing means is disposed on or along the bottom of the apparatus, by which the size of the sheet confining member can be reduced, no special space is required for the urging force generating means. 
     By removing the urging force to the sheet confining member, the sheet can be released, and the sheet confining member is not moved to a great extent, when, for example, the recording medium is pulled out from the nip between the sheet confining member and the platen, while releasing the urging of the sheet confining member to the platen. 
     As a result, the size of the apparatus can be reduced, and in addition, the possibility of the interference between the sheet confining member and the recording head or the like can be prevented when the urging force to the platen is released. 
     Further according to the present invention, the movable member for supporting the rowel is press-contacted to a positioning member, and therefore, the constant positional relation can be maintained between the rowel and the discharging roller. 
     Therefore, if the movable member is a cover member of the apparatus, it can be used also as a supporting member for the rowel, and therefore, the size of the apparatus can be reduced. In addition, the number of parts can be reduced, thus permitting high accuracy assembling of the apparatus, by which the operation of the sheet discharging system can be maintained in good order. 
     According to a further aspect of the present invention, when the rowel functioning as a follower rotatable member urges the recording medium to the sheet discharging roller functioning as the main rotatable member, for example, the shaft supporting the rowel provides the urging force for the press-contact, no additional means or mechanism is required to provide the urging force. 
     As a result, the size of the apparatus can be reduced, and the structure is simplified, and the accuracy of the apparatus can be increased. By the use of the coil spring as the shaft, the sheet conveying properties can be improved with lower cost maintained. 
     According to a further aspect of the present invention, the core member of the roller can be produced at relatively low cost, and in addition, the tube of the elastic material such as rubber is relatively inexpensive, so that the cost of the conveying roller can be reduced. 
     As a result, the cost of the ink jet recording apparatus can be reduced. 
     According to a further aspect of the present invention, the recording sheet discharged is first conveyed through the air, and then is contacted to the top end of the tray, and slides on the top end. Subsequently, when the trailing edge of the recording sheet is discharged through the discharge port, the sliding movement stops, and the trailing edge of the recording sheet falls substantially vertically. 
     As a result, the recording sheet discharged is stacked on the tray with minimum sliding contact with the tray or the topmost sheet on the tray. In addition, the sliding contact portion of the topmost sheet on the tray is the portion where the ink is more fixed, so that the contamination by the sliding movement can be prevented. 
     Furthermore, at the trailing end portion of the recording sheet, the sheet falls through the air without relative sliding movement between the sheets, so that the contamination by the ink can be prevented. 
     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.