Ink jet recording apparatus

Abstract: An ink jet recording apparatus and an ink cartridge (61, 62) for use in this apparatus. The recording apparatus has a transport unit (A) for transporting the recording medium (2b), a recording unit (B) having a carriage portion on which a recording head (39 to 42) capable of dis­ charging an ink supplied from an ink containing portion to effect recording is mounted, a recovery unit (C) capable of restoring the function of discharging the ink through the discharge port. The transport unit (A), the recording unit (B) and the recovery unit (C) are independently separable from each other. Ink passage for communication between the ink containing portion and the recording head (39 to 42) can be disconnected while being shutting off in each unit. The ink cartridge (61, 62) has a casing, a plurality of ink containers disposed in the casing, and positioning members formed on the ink containers. The ink containers are positioned by engaging the positioning members with each other.

Description: BACKGROUND OF THE INVENTION Field of the Invention This invention relates to an ink jet recording apparatus for effecting recording on a recording medium by discharging ink through a discharge opening. More particularly, this invention relates to an apparatus having separable units having different functions and independently attached to the apparatus. Related Background Art Conventionally, a type of ink jet recording apparatus for effecting recording by jetting droplets of ink through an opening or a nozzle of a recording head according to recording data has a section for transporting a recording medium, a section on which the recording head is mounted, a recovery unit for preventing an ink supply passage and the nozzle from clogging and for recovering each of the passage and the nozzle from a clogged state. Referring to Fig. 1 which is a schematic perspective view of a conventional ink jet recording apparatus of this type, a transport roller 504 for transporting a recording medium is axially supported through a shaft 503 on chassis 501 and 502 and is driven by a driving source (not shown) through a belt transmission mechanism 505. The recording medium is transported while being guided by a paper pan 506 and a guide plate 507. Recording heads 508 to 511 having a plurality of ink discharge port are mounted on a carriage 512 which are supported and guided by a pair of guide rails 513 fixed between the chassis 501 and 502 and which are moved for scanning by a driving source (not shown) through a belt 514. An interchangeable ink cartridge 515 is connected to the carriage 512 by a supply pipe 516 to supply ink to the recording heads 508 to 511. A recovery unit 517 has caps 518 to 521 reciprocatively moved by a driving source (not shown), and a pump for producing a pressure by the driving source. The transport portion, the head mount portion, the recovery unit 517 and so on are integrally assembled on the chassis 501 and 502 and chassis 522 and 523. This conventional apparatus, however, can be actually used for recording to confirm whether or not the apparatus works correctly only after the overall assembly has been completed. If a malfunction takes place, troublesome operations for dismounting the components for repair of the malfunctioning portion and thereafter reassembling the components are required. It is also required to inspect the reassembled components again. Moreover, once the ink flow into the ink supply passages, it is necessary to employ means for copying with the outflow of the ink during the operation of disconnecting intermediate portions of the passage. This operation is very difficult in respect of maintenance also. It is sometimes necessary to interchange the whole of the recording unit, which is very wasteful. In the field of electrophotography, US-A-4,386,838 discloses an arrangement using independently separable units. In this arrangement, each of the units, e.g., a developing device and a cleaning device is made separable. However, the invention disclosed in that publication relates to the field of electrophotography different from that of ink jet recording and therefore any consideration is paid to use of ink including supply of ink to the recording head. An ink jet recording apparatus according to the pre-characterizing clause of claim 1 is known from GB-A-1582781. The recording unit of this known ink jet apparatus is connected to the transport unit by means of a hinge between the chassis of the transport unit and the frame of the recording unit. The recovery unit is integrated into the recording unit. The construction of this known ink jet recording apparatus makes it difficult to assemble and to inspect the units thereof. Therefore, the maintenance service is difficult and the costs of production and of maintenance are high. It is an object of the present invention to provide an ink jet recording apparatus according to the pre-characterizing clause of claim 1 which is remarkably improved in producibility, reliability and facility of maintenance service. This object is achieved by the ink jet recording apparatus according to claim 1. The features of this invention will become obvious upon an understanding of the illustrative embodiments about to be described or will be indicated in the appended claims, and various advantages not referred to herein will occur to one skilled in the art upon employment of the invention in practice. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic perspective view of an example of a conventional ink jet recording apparatus; Fig. 2 is a perspective view of an ink jet recording apparatus in accordance with an embodiment of the present invention; Fig. 3A is a perspective view of a transport unit in accordance with the embodiment of the invention; Fig. 3B is a diagram of a connection method in accordance with the embodiment of the invention; Figs. 3C and 3D are diagrams of another example of the connection method; Fig. 4 is a diagram of a recording unit in accordance with the embodiment of the invention; Fig. 5 is a diagram of a recovery unit in accordance with the embodiment of the invention; Fig. 6 is a perspective view of the recording unit and the recovery unit in a connected state in accordance with the embodiment of the invention; Fig. 7 is a sectional side view of a transport unit having a means for constantly maintaining the distance between the recording head and the recording surface in accordance another embodiment of the invention; Figs. 8A and 8B are diagram of an ink passage shutting off method; Figs. 8C and 8D are diagram of another example of the ink passage shutting off method; Fig. 8E is a diagram of an ink passage connection method. DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. First, an ink jet recording apparatus will be described below in which independently separable units are connected and which thereby effects recording on a recording medium. The ink jet recording apparatus described below has a transport unit including transport means for transporting a recording medium and a driving source for driving this transport means; a recording unit including a carriage on which recording heads are mounted and which effects scanning on the recording medium, and a carriage scanning driving source; and a recovery unit including caps, a pressure generation source and a driving source for driving the caps and the pressure generation source. In this apparatus, the transport unit, the recording unit and the recovery unit are independently separable, and ink supply passages can be closed off in each single unit. Details of the present invention will be described below with reference to an embodiment illustrated in the following figures. Fig. 2 is a perspective view of an ink jet recording apparatus which represents an embodiment of the present invention; Fig. 3A is a perspective view of a transport unit; Fig. 4 is a perspective view of a recording unit; Fig. 5 is a perspective view of a recovery unit; and Fig. 6 is a perspective view of the recording unit and the recovery unit, showing a connected state of these units. Referring to Fig. 2, the ink jet recording apparatus has a transport unit A which places, supplies, transports and exhausts a recording medium, a recording unit (hereinafter referred to as "carriage unit") B on which recording heads are mounted and which effects scanning, and a recovery unit C which supplies ink, prevents ink clogging and recovers components from a clogged state. First, the transport unit A of the ink jet recording apparatus in accordance with the embodiment of the present invention will be described below. Referring to Figs. 2 and 3A, the transport unit A has a chassis 24 and a cassette 25 on which recording medium 26 (recording paper or the like) are mounted. In this embodiment, two transport routes for cassette feed and manual feed are formed. The recording medium 26 on the cassette 25 are successively in the downstream direction supplied to transport rollers 27 by rollers R. A placement table 28 is used for manual feed. Feed rollers 29 serve to transport the recording medium 26. Separator pieces 30 abut against the feed rollers 29 by a spring (not shown) to separate the recording medium 26 one after another. Sheet guide plates 31 and 32, a press plate 33 for pressing the recording medium 26 downward, and a guide plate 34 are provided as sheet guide means. The guide plate 34 is rotatably supported on a shaft of the feed rollers 29. The guide plate 34 has a bearing portion 34a and rotatably supports contact rollers 36. The contact rollers 36 contact the transport rollers 27. Each recording medium sheet 26 is transported by the transport rollers 27 and the contact rollers 36. Pairs of exhaust rollers 37 and 38 serve to exhaust each recording medium 26 by pinching it after recording has been effected on the medium. The feed rollers 29, the transport rollers 27 and the exhaust rollers 37 and 38 form a transport means for transporting the recording medium 26 and are driven by a driving source comprising a motor (not shown) and a transmission mechanism (not shown) provided on the chassis 24. Tapped holes 24a and U-shaped grooves 24b for detachably connecting the carriage unit B and the recovery unit C in a connected state (a main body unit D) to the transport unit A are formed in the chassis 24. The way of detachably connecting a frame 45 of the carriage unit B to the U-shaped grooves 24b is as described below in detail with reference to Fig. 3B. The recovery unit C described later is also detachably connected to the carriage unit B in the same way. The frame 45, which also forms the frame of the main body unit D after the carriage unit B and the recovery unit C have been connected, is obliquely inserted into each of the U-shaped grooves 24b (to a position a shown in Fig. 3B) and is thereafter rotated counterclockwise (in the direction of the arrow c ) to a horizontal position (a position b ). In this position, an upper surface of the frame 45 is restrained by a projection 24c forming a part of the U-shaped groove 24b while a lower surface of the frame 45 is restrained by an upper surface 24d of the frame 24. Thus, the main body unit D is mounted while positioned on the transport unit A in the vertical direction. Next, the carriage unit B will be described below. Referring to Figs. 2, 4 and 6, recording heads 39 to 42 for printing of, for example, four colors (yellow, magenta, cyan and black) are mounted on a carriage 43 forming a mount portion for mounting the recording heads. A carriage shaft 44 on which the carriage 43 travels is supported on the frame 45. A motor 46 is disposed under a lower surface of the frame 45. A belt 47 is engaged with the carriage 43 and is stretched between pulleys 48 and 49 to move the carriage 43 by the rotation of the motor 46 through a belt 50. A lengthwise film 51 has a multiplicity of slits arranged in the longitudinal direction. The position of the film 51 is detected by a sensor provided on the carriage to control the motor 46. A cover 52 is provided to protect flexible tubes 53 for supplying the inks to the recording heads 39 to 42. More specifically, the flexible tubes 53 serve to supply the respective color inks from an ink containing portion comprising a black ink cartridge 62 and a color cartridge 61 to the recording heads 39 to 42 on the carriage 43. Other ends of the tubes 53 are connected to a joint 54 and another end of the joint 54 is connected to needles 55. The tubes 53 and the needles 55 form ink supply passages for supplying ink to the recording heads 39 to 42. Two attachment holes 45a to which the transport unit A is detachably connected are formed in the frame 45. Next, the recovery unit C will be described below. Referring to Figs. 2, 5 and 6, the recovery unit C has a recovery device 56 including caps 57 to 60 formed of a flexible material and a suction pump (not shown), the interchangeable replenishment ink cartridges 61 and 62 having internal sections for receiving waste ink discharged from the recovery device 56 through a tube 63 and a joint 64. Outlets 65 corresponding to the respective inks are provided on the joint 64. The recovery device 56, the joint 64 and the ink cartridges 61 and 62 are integrally held on a frame 66. The frame 66 has a tapped hole 66a and U-shaped grooves 66b for detachably connecting the recovery unit to the carriage unit B. The operation of the thus-constructed recording apparatus will be described below with reference to Fig. 2. The recording medium 26 provided in the cassette 25 is supplied to the nip between the transport rollers 27 and the contact rollers 36 by the forwarding rollers R, and is transported to a position P as indicated in Fig. 2 by the transport rollers 27. At the time of recording, the inks are supplied from the ink cartridges 61 and 62 to the recording heads 39 to 42. Energy generating elements provided in the recording heads upstream of their discharge openings are driven according to the recording information to make the inks fly out of the openings. Droplets of the inks are thereby attached to and absorbed into the surface of the recording medium 26 to fix recording dots, thereby successively effecting recording. As the recording proceeds, the motor 46 is rotated to reciprocatively move the carriage 42 in the main scanning direction. During this operation, a portion of the carriage 43 slides on the guide plate 34 for scanning along the carriage shaft 44. The carriage 43 is moved to a position at which it is superposed on the recovery device 56 (hereinafter referred as "recovery position") if a discharge malfunction takes place owing to ink clogging in the openings of the recording heads 39 to 42 or attachment of dust to the openings, or this movement is effected periodically. At this time, the caps 57 to 60 are in a retracted position and do not obstruct the movement of the carriage 43. When the carriage 43 is at the recovery position, projections 43a formed on the carriage 43 are positioned so as to be engaged with holes (not shown) formed in the recovery device 56. After the carriage 43 has been stopped at the recovery position, the caps 57 to 60 are placed on the faces of the recording heads 39 to 42 so as to form closed systems, the suction pump is operated to draw the attached impurities or dust together with ink, and the waste ink is exhausted into the ink cartridge 61 or 62 through the tube 63. The way of assembly of this recording apparatus will now be described below. The way of detachably connecting the recovery unit C to the carriage unit B will be first described. Referring to Figs. 4, 5 and 6, the U-shaped grooves 66b of the recovery unit C are positioned at engaging portions 45b of the chassis 45 of the carriage unit B and detachably fitted to the same. Then, a screw 67 is inserted into a hole 67a of in the chassis 45 corresponding to the tapped hole 66a of the recovery unit C and is screwed into this hole to fix the carriage unit B and the recovery unit C to each other. The carriage unit B and the recovery unit C are thereby integrally connected to form the main body unit D. Next, the joint 54 of the carriage unit B and the joint 64 of the recovery unit C are connected to make the needles 55 and the outlets 65 communicate with each other, thereby forming the ink supply passages. Thus, the ink supply passages for supplying inks from the ink cartridges 61 and 62 to the recording heads 39 to 42 and the ink passage for collecting ink in the ink cartridge via caps 57 to 60 can be disposed in the same unit based on integrally connecting the carriage unit B and the recovery unit C to form the main body unit. It is thereby possible to markedly reduce the leakage of the inks. The carriage unit B and the recovery unit C thereby assembled (main body unit D) are combined with the transport unit A shown in Fig. 3A. The main body unit D is detachably connected to the transport unit A as described below. Engaging end portions 45c of the frame 45 of the carriage unit B are positioned in the two U-shaped cuts 24b formed in the chassis 24 as shown in Fig. 3A and are detachably fitted therein. Then, screws 67 are inserted into the two holes 45a of the frame 45 corresponding to the tapped holes 24a and are screwed into the same, thereby fixing the main body unit D and the transport unit. The assembly of the ink jet recording apparatus is thereby completed to enable recording. It is possible to modify the transport unit A to constantly maintain the accuracy with which the distance between the discharge openings of the recording heads and the recording surface of the recording medium is determined after the units have been assembled by being connected, even though the transport unit A, the carriage unit B and the recovery unit C are separable from each other or the main body unit D and the transport unit A are separable. A transport unit Aa designed for this effect in accordance with another embodiment of the present invention will be described below. A transport unit Aa is independently separable from the main body unit D or from the carriage unit B and the recovery unit C as in the case of the transport unit A. Portions for connection to each of the other units are omitted in Fig. 7, but they may be of the same type as those of the above-described embodiment. For ease of understanding of this embodiment, a carriage 43 and recording heads 39 to 42 are also illustrated, which are provided in the carriage unit B as in the case of the above-described embodiment. Fig. 7 shows a state in which recording medium sheets 26 are placed on a cassette 25. A slider 128 is provided on a carriage 43. The slider 128 slides on a guide plate 125 while supporting a moment acting on the carriage 43 on a carriage shaft 44 (in the direction of the arrow W). Feed rollers 126 serves to transport each recording medium 26. Separator pieces 138 abut against the feed rollers 126 by a spring 139 to separate the recording medium sheets one after another. Sheet guide plates 123 and 130 are provided as a sheet guide means for guiding the recording medium 26. A press-down plate 33 serves to press the recording medium 26 downward. The guide plate 125 is rotatably supported on a shaft 127 of the feed rollers 126, has bearing portions for rotatably supporting contact rollers 131. The contact rollers 131 contact the guide plate 130. When the recording medium 26 is transported between the guide plate 130 and the contact rollers 131, the guide plate 125 rotates on the shaft 127 according to the thickness of the sheet. With this rotation the carriage 43 is rotated clockwise on the shaft 44 with the slider 128 contacting the guide plate 125. Accordingly, the distance between the jet holes of the recording heads 39 to 42 and the recording surface can be constantly maintained irrespective of the thickness of the recording medium 26. Thus, the transport unit Aa of this embodiment is capable of maintaining the desired distance between the discharge openings of the recording heads and the recording surface of the recording medium even though some attachment error occurs when, for example, the transport unit Aa is connected to the main body unit D. According to the above description, the apparatus units are assembled in order of the carriage unit B, the recovery unit C and the transport unit A. However, the assembly order is not limited to this. For example, these units can be assembled in order of the transport unit A, the carriage unit B and the recovery unit C. Because the units are constructed separately as described above, each of the transport unit A, the carriage unit B and the recovery unit C can be assembled and checked on a separate production line. In this case, there is no possibility of a malfunction of one of the units A to C influencing the other units. Even if occurrence of a malfunction of, for example, the transport unit A is found after the assembly of the whole of the apparatus has been completed, the unit can be separated by only removing two screws 67; there is no need for an operation which may cause a leak of ink, e.g., disconnecting the ink supply pipes. It is also possible to prevent an ink leak in the carriage unit B and the recovery unit C during disassembly in the case of a malfunction of the carriage unit B or the recovery unit C. That is, the ink supply passages are connected through the joints 54 and 64 between the carriage unit B and the recovery unit C, and these joints may be constructed in such a manner that the outlets 65 are formed of flexible members which are closed by itself but are opened for communication through the supply passages only when the needles 5 are inserted, thereby preventing an ink leak in each of the carriage unit B and the recovery unit C. Arrangements for shutting off the ink supply passages will be described below. Referring to Figs. 8A and 8B, an example of a shut-of structure is illustrated. When the carriage unit B and the recovery unit C are detached from each other, the needles 55 are disconnected from the outlets 65. The needles disconnected from the outlets 65 are fitted to a sealing means formed by projections 55a formed on a side plate 70 of the carriage unit B (as shown in Fig. 8A). The end openings of the needles 55 are thereby closed by the projections 55a to prevent the inks from leaking out. Referring to Figs. 8C and 8D, another example of the shut-off structure is illustrated. In this example, the needles 55 are restrained by engaging portions 55b formed on the side plate 70 with their openigns facing upward and maintained at substantially the same height as the jet holes of the recording heads 39 to 42. Substantially equal water heads are thereby maintained in the needles and the recording heads, thereby preventing the inks from leaking out. Referring to Fig. 8E, another example of each outlet 65 is illustrated. A spring member 65b is set inside an outlet 65 so as to urge a sealing ball 65c toward the opening 65d. The diameter of the opening 65d is smaller than that of the sealing ball 65c. The opening 65d is therefore completely sealed with the sealing ball 65c. A corresponding needle 55 having a cut-out portion 55d formed at its extreme end is inserted into this opening, and the needle 55 is pressed against the outlet 65 until the needle 55 and the outlet 65 are connected by engagement between small protrusions 55c and 65a, thereby providing a communication between the ink supply passages of the needle 55 and the outlet 65 through an opening formed by the sealing ball 65c and the cut-out portion 55d. In the above-described embodiments, the carriage unit B and the recovery unit C are integrally combined before they are mounted on the transport unit A. However, the present invention can also be achieved by a construction in which the carriage unit B and the recovery unit C are respectively attached to the transport unit A. The number of recording heads is not necessarily be plural. The ink cartridges may be of a type mounted on the carriage. In the above-described embodiments, each unit is connected by fastening with screws. However, the connection means in accordance with the present invention is not limited to this type; another means for detachably connecting the units may be adopted, which will be described below with respect to connection between the transport unit A and the main body unit D. As shown in Fig. 3D, a cylindrical portion 24f having a head 24e (diameter of head 24e > diameter of cylindrical portion 24f) is formed on the frame 24 of the transport unit A. On the other hand, as shown in Fig. 3C, a hole 45d is formed in the frame 45 of the main body unit D, and an elastic member 45c is provided on the inner peripheral surface of the hole 45d. The diameter of the hole 45d is approximately equal to that of the cylindrical portion 24f, and the diameter of the elastic member 45c is approximately equal to that of the head 24e. To connect the transport unit A and the main body unit D, the head 24e of the transport unit A of the transport unit A is formed into the frame 45 of the main body unit D. The elastic member 45c is thereby deformed outwardly and is engaged with the cylindrical portion 24f (in a position shown in Fig. 3D). To disconnect these units, the frame 45 of the main unit D is moved upwardly as viewed in Fig. 3D until the cylindrical portion 24f and the elastic member 45c are disengaged. Thus, the main body unit D and the transport unit A can be detachably connected. The above-described transport unit is provided with the cassette, the feed rollers, the transport rollers, the manual feed placement table, the paper guide and so on. However, the transport unit of the present invention may have the feed rollers alone. The above-described recording unit is provided with the recording head mount portion, the carriage, the belt for reciprocatively moving the carriage, the motor for driving the belt, and so on. However, the recording unit of the present invention may have the recording head mount portion alone. The above-described recovery unit is provided with the caps, the ink cartridges, the tube, the pump and so on. However, the recovery unit of the present invention may have only a function of removing ink attached in the vicinity of the discharge openings by using an absorbing member or the like, provided that the function of jetting inks through the discharge openings can be restored. In accordance with the above-described embodiments, the recording medium transport unit, the carriage unit and the recovery unit are constructed as independently separable units, and each unit can be assembled and checked separately. It is thereby possible to greatly improve the apparatus in both producibility and reliability. Since the ink supply passages can be shut off in each single unit, there is no possibility of a leak of the ink in each unit even if the unit is dismounted after the ink has been filled. The maintainability is thereby improved remarkably. Further, the present invention enables interchange of carriage units differing in recording density to improve the extendability of the recording apparatus, i.e., to grade up the apparatus. The present invention can be applied to any other type of ink jet recording system, e.g., one using electromechanical converters such as piezo-electric elements. However, the present invention is specifically effective when applied to the bubble jet type ink jet recording head or recording apparatus proposed by Canon Inc, because this type of apparatus enables improvements in recording density resolution. For a typical construction and a principle of this type of apparatus, a basic principle disclosed in, for example, US-A-4,723,129 and US-A-4,740,796 is preferably used. The system disclosed therein can be applied to each of an on-demand type and a continuous type. Specifically, in the case of the on-demand type, it is effective because film boiling can be effected on a heat application surface of a recording head by producing thermal energy in an electrothermal energy converter disposed to face a seat or liquid passage in which a liquid (ink) is retained based on applying at least one driving signal for effecting an abrupt increase in temperature sufficient for nucleate boiling according to recording information, thereby forming bubbles in the liquid (ink) in one-to-one correspondence with the driving signal. The liquid (ink) is discharged through a discharge opening by the growth/contraction of the bubbles to form at least one droplet. If this driving signal is provided in the form of pulses, growth/contraction of bubbles can be suitably effected instantaneously, thereby achieving jetting of the liquid (ink) with improved response. The use of a pulse driving signal is therefore more preferable. Preferably, pulse driving signals such as those disclosed in US-A-4,463,359 and US-A-4,345,262 may be used. It is possible to further improve the recording performance by adopting conditions disclosed in 4,313,124 relating to the rate of increase in the temperature of the heat application surface. The present invention also includes recording head arrangements in which heat application portions are disposed on bending regions as disclosed in US-A-4,558,333 and US-A-4,459,600, as well as arrangements based on a combination of jetting holes, liquid passages (linear liquid passages or perpendicular liquid passages) and electrothermal converters as disclosed in the above-mentioned specifications. In addition, the present invention is also effective when applied to an apparatus based on an arrangement, such as the one disclosed in JP-A-59-123670, in which a common slit is provided for a jetting portion of a plurality of electrothermal converters, or an arrangement, such as the one disclosed in JP-A-59-138461, in which an opening for absorbing pressure waves is formed so as to face a jetting portion. That is, according to the present invention, the reliability and the efficiency of recording can be improved irrespective of the construction of recording head. Further, the present invention can be effectively applied to a full-line type recording head having a length corresponding to the maximum width of the recording medium which can be used for the recording apparatus. Such a recording head may be arranged to obtain the suitable length by using on the combination of a plurality of heads or an integrally formed one recording head. The present invention is effective with respect to any other types of recording heads, including the above-mentioned serial type, a recording head fixed to the main apparatus body, an interchangeable tip type recording head which can be electrically connected to the main apparatus body and to which an ink can be supplied from the main body when attached to the main body, and a cartridge type recording head on which an ink tank is integrally mounted. It is preferable to add, as a recording apparatus component, auxiliary means for a preliminary operation for the recording head and so on, because it enables an improvement in the stability of the effects of the present invention. More specifically, these additional means are, for example, a means for capping the recording head, a means for cleaning the recording head, a pressurizing or absorbing means, and a preliminary heating means based on an electrothermal converter or any other type of heating element or a combination of these elements. Using a preliminary jetting mode separately from recording is also effective in performing recording with stability. The kind of recording head or the number of recording heads to be mounted may be limited to one for single color ink or may be plural in correspondence with a plurality of inks differing in recording color or density. For example, the present invention is very effective when applied to an apparatus having a recording mode of using a multiplicity of different colors or full-color mode based on color mixing with one integrally formed recording head or a plurality of recording heads combined, as well as a mode of recording in a main color such as black. In the description of the above-described embodiments, the ink is referred to as a liquid. However, the ink in accordance with the present invention may be an ink solidified at a temperature generally equal to or lower than room temperature and softened or liquefied at room temperature, or an ink liquefied when an operating recording signal is applied, since, in ink jet recording systems, the temperature of the ink is controlled in a range of 30 to 70°C to set the viscosity of the ink to a stable jetting range. The present invention is also applicable with respect to other types of ink or other kinds of use. That is, an ink which is solidified under an ordinary condition may be used for the purpose of preventing the temperature of the ink from excessively increasing by the applied thermal energy based on using the applied energy as the energy for a phase change of the ink from a solid state to a liquid state or for the purpose of preventing evaporation of the ink. In either case, the ink is liquefied by the application of thermal energy according to the recording signal to be jetted in the liquefied state, and. Also, an ink which is liquefied only when it receives thermal energy is controlled so as to start solidifying when it reaches the recording medium. Such an ink may be used in such a manner that it faces an electrothermal element while being retained in a liquid or solid state in a recessed portion or a through holes of a porous seat, as disclsoed in JP-A-54-56847 JP-A-60-71260. According to the present invention, the above-described film boiling system is most effective in using each of these inks. The ink jet recording apparatus in accordance with the present invention may be an image output terminal of an information processing system such as a computer, a copier combined with a reader or the like, or a facsimile apparatus having transmitting and receiving functions. As described above in detail, the ink jet recording apparatus in accordance with the present invention is composed of independently separable units detachably connected to each other.

Claims: An ink jet recording apparatus for effecting recording on a recording medium (26) by discharging ink through a discharge opening, comprising: a transport unit (A, Aa) having transport means for transporting the recording medium (26) and having a chassis (24) on which the transport means is mounted; a recording unit (B) having a mount portion (43) on which a recording head (39 to 42) capable of discharging ink supplied from an ink containing portion (61, 62) to effect recording is mounted and having a frame (45) on which the mount portion is mounted; and a recovery unit (C) having a recovery device (56) for restoring the function of discharging the ink through the discharge opening; characterized in that said transport unit (A, Aa), said recording unit (B), and said recovery unit (C) are separable from each other; in that said recovery unit (C) comprises a frame (66) on which the recovery device (56) is mounted; and in that said chassis (24) of said transport unit (A, Aa), said frame (45) of said recording unit (B), and said frame (66) of said recovery unit (C) are detachably connected with each other to form said ink jet recording apparatus. An ink jet recording apparatus according to claim 1, wherein said transport unit (A, Aa), said recording unit (B) and said recovery unit (C) are connected by fastening screw members inserted in holes (24a, 45a, 66a, 67a) formed in said frames (45, 66) and said chassis (24). An ink jet recording apparatus according to claim 1, wherein said frames (45, 66) and said chassis (24) are connected by engaging projections (45b) engaging portions (24b, 66b) engageable with said projections. An ink jet recording apparatus according to claim 1, wherein said recording head (39 to 42) has an electrothermal converter capable of generating thermal energy according to a recording signal, and discharges the ink by using this thermal energy. An ink jet recording apparatus according to claim 1, wherein said transport unit (A) comprises a cassette (25), a feed roller (29, 126), a transport roller (27), a manual feed placement table (28), and a sheet guide means (31 to 34, 123, 130). An ink jet recording apparatus according to claim 1, wherein said transport unit (A, Aa) comprises a driving source for driving said transport means. An ink jet recording apparatus according to claim 1, wherein said recording unit (B) comprises, a carriage (43) forming said recording head mount portion, a belt (47) for reciprocatively moving the carriage, and a motor (46) for driving said belt. An ink jet recording apparatus according to claim 1, wherein said recovery unit (C) comprises an ink cartridge (61, 62) forming said ink containing portion and wherein said recovery device (56) comprises a cap (57 to 60), a tube (63) and a pump. An ink jet recording apparatus according to claim 8, wherein said recovery device (56) comprises a driving source for driving said cap (57) and said pump. An ink jet recording apparatus according to claim 1, wherein said recovery device includes an ink absorbing member. An ink jet recording recording apparatus according to claim 1, further comprising means for maintaining a constant distance between said recording head (39 to 42) and the recording surface of the recording medium (26) irrespective of the thickness of the recording medium (26), said means comprising a slider (128) provided on said mount portion (43) and sliding on a guide plate (125) rotatable according to the thickness of the recording medium (26). An ink jet recording apparatus according to claim 11, wherein, by its rotation, said guide plate (125) causes said recording head (39 to 42) to swing so that the distance between the discharge opening of said recording head (39 to 42) and the recording surface of the recording medium (26) is maintained constant. An ink jet recording apparatus according to claim 1, further comprising at least one ink supply passage (53, 55) through which said ink containing portion (61, 62) and said recording head (39 to 42) communicate with each other, and disconnection means (54, 64) for disconnecting said ink passage between said ink containing portion (61, 62) and said recording unit (B). An ink jet recording apparatus according to claim 13, wherein said carriage unit (B) as a support member (55b) for supporting the ink passage (53, 55) at one disconnected end of the same so that the end opening therefore faces upward and is substantially flush with the discharge opening of said recording head (39 to 42). An ink jet recording apparatus according to claim 13, wherein said carriage unit (B) has sealing means (55a) for closing the opening of the disconnected end of said ink passage (53, 55). An ink jet recording apparatus according to claim 1, wherein the transport unit (A, A a ) is mounted on a body of the ink jet recording apparatus and wherein the recording unit (B) is positioned to the transport unit (A,A a ) by a mechanical connection.

Inventors: NOJIMA TAKASHI, TAKEMURA MAKOTO, TERASAWA KOJI, YOKOI KATSUYUKI, NOJIMA, TAKASHI, TAKEMURA, MAKOTO, TERASAWA, KOJI, YOKOI, KATSUYUKI
Applicants: CANON KK, CANON KABUSHIKI KAISHA
Application year: 1990
Main classification: B41J2
IPC codes: B41J2, B41J13, B41J19, B41J29