Ink jet recording apparatus and pump mechanism for use therewith

Abstract: A pump mechanism of ink jet recording apparatus comprises a pump having a suction portion for sucking from a sucked member, said pump switching the suction or non-suction from said suction portion with a reciprocating motion of piston within a cylinder (24) without having a valve, a carrying member for carrying waste ink from said pump which is connected to said pump, said carrying member opening to the atmosphere and a prevention mechanism for preventing a backflow of ink within pump from said suction portion of said pump to the outside of said pump which is caused by the reciprocating motion of said cylinder (24) said prevention mechanism being an pump internal mechanism.

Description: The present invention relates to an ink jet recording apparatus, and more particularly to an ink jet recording apparatus comprising a pump mechanism for sucking waste ink. A recording apparatus such as a printer, a copying machine and a facsimile terminal equipment is constituted to record an image consisting of dot patterns onto a recording medium such as paper or plastic sheet, based on image information. The recording apparatus can be classified into the ink jet, wire dot-matrix, thermal and laser beam systems. According to the ink jet system (ink jet recording apparatus) the ink is discharged from a recording head for depositing ink onto a recording medium to record. This ink jet recording apparatus is a non-impact type having such features as low noise, high-density and high-speed recording ability, and the color image recording capability by use of color inks. In the ink jet recording apparatus as above described, wetting of waste ink may sometimes occur on a discharge port face of recording head due to a fine mist Of ink floating with a recording medium, or the splashing of discharged ink from the recording medium. If waste ink as above mentioned may adhere to the discharge port face of recording head, the ink discharge direction or speed may change, or the particle sizes of discharged ink droplets may be dispersed, so that the quality of recording may be sometimes decreased. As means for preventing such a phenomenon, an ink jet recording apparatus is provided with a suction station for sucking waste ink as above described. However, in a conventional ink jet recording apparatus, a pump for the suction station is provided with a valve which opens or closes, in which waste ink is sucked by a piston reciprocating within a cylinder. The pump with such a constitution had a problem that a repeating mechanism of valve might cause a malfunction due to fixing of ink. However, as few troubles originating from the problem occurred, a fundamental resolution was not achieved. Thus, the present inventors examined a constitution in which the contact members are used for the valve function, by elminating the open/close valve mechanism, but a new problem occurred. That is, there is an advantage that its construction is simple, but the fouling of ink becomes conspicuous within apparatus. This fouling was often seen particularly on a head surface within a cap. A detailed examination of this phenomenon by a present inventor showed that a back flow from the inside of pump toward the cap would be generated. EP-A-0 375 407 shows an ink jet recording apparatus having a pump mechanism for cleaning the discharge port surface of a recording head. The content of this document falls under Article 54, paragraph 3 with respect to the designated Contracting States DE, ES, FR, GB, IT and NL. Thus, the document is not relevant to the question of inventive step. The pump mechanism according to EP-A-0 375 407 has a suction portion for sucking waste ink from an ink jet recording head and a discharge portion for discharging the waste ink via a waste ink tube to an exhaust member which is constituted by a paper feed roller. The paper feed roller is provided with an ink absorbing member for absorbing the discharged ink. An object of the present invention is to provide a pump mechanism for an ink jet recording apparatus in which the backflow of waste ink in the vicinity of the exhausting port of the pump having no valve is prevented. The present invention provides a pump mechanism for an ink jet recording head according to claim 1. According to another aspect of the present invention an ink jet recording apparatus is provided comprising a pump mechanism according to claim 1 According to another aspect of the present invention an ink jet recording apparatus is provided comprising a recording head for recording onto a recording member, a plurality of consecutive waste ink absorbing members for absorbing the ink adhering to a cleaning member for cleaning a discharge port face of said recording head and a pump mechanism according to claim 1 BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view, partially broken away, showing a constitution for essential parts of an ink jet recording apparatus to which the present invention is preferably applicable. Fig. 2 is a perspective view of a set lever and a blade lever which bear on a set shaft as shown in Fig. 1. Fig. 3 is a perspective view of a timing gear as shown in Fig. 1. Fig. 4 is a partial perspective view typically showing the operation of a wiper as shown in Fig. 1. Fig. 5 is a perspective view showing a waste ink absorbing system as shown in Fig. 1. Fig. 6 is a longitudinal cross-sectional view of Fig. 5. Fig. 7 is a plan view of Fig. 5. Fig. 8 is an exploded perspective view of a recovery pump and a cap as shown in Fig. 1. Fig. 9 is a perspective view of a piston unit as shown in Fig. 8. Fig. 10 is a longitudinal cross-sectional view of the pump as shown in Fig. 8. Fig. 11 is a longitudinal cross-sectional view of the pump as shown in Fig. 8, when the piston is positioned at an upper dead center. Fig. 12 is a typical view for illustrating a configuration of a waste ink absorbing system where a plurality of waste ink absorbing members are used. Fig. 13 is an example of a covering member according to an embodiment of the present invention. Fig. 14 is an example of a covering member according to another embodiment of the present invention. Fig. 15 is an example of a covering member according to another embodiment of the present invention. Fig. 16A is an example of a pump according to an embodiment of the present invention. Fig. 16B is a cross-sectional view taken along a line K-K of Fig. 16A. Fig. 16C is a view according to the direction of an arrow L of Fig. 16A. Fig. 17A is an example of a pump according to another embodiment of the present invention. Fig. 17B is a view according to the direction of an arrow M of Fig. 14A. Fig. 18 is an example of a pump according to another embodiment of the present invention. Fig. 19 is an example of a pump according to another embodiment of the present invention. Fig. 20 is an example of a pump according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described specifically with reference to the drawings. Fig. 1 is a perspective view showing a constitution for essential parts of an ink jet recording apparatus to which the present invention is preferably applicable. In Fig. 1, 1 is a chassis backward of which are stood a left-hand plate 1a and a right-hand plate 1b which also serve as the guide for a recording medium 40, on a right-hand end portion of which is stood a front side plate 1c, and on a front portion of which is stood a carrier guide plate 1d. The carrier guide plate 1d as above described is formed with a long hole 1e for guiding a carrier 6, a guide roller 10 of which can slide by fitting into the long hole 1e. The chassis 1 as above described is formed with a motor mounting hole (not shown) on which a carrier motor 11 for driving the carrier 6 bears to be rotatable. At a predetermined position on a left-hand end portion of the chassis 11 as above described is fixed a lead arm 1h, at a tip portion of which is provided a bearing portion 1i for rotatably bearing a lead screw 2 for driving the carrier, as well as supporting it in the axial and radial directions. The lead screw 2 as above described is formed with a lead groove 2a of a predetermined pitch. A lead pulley 3a is fixed on a carrier home position side of the lead screw 2 as above described, and a circumferential groove (recovery groove) 3b perpendicular thereto useful for the recovery operation is formed at a capping position in the neighborhood of a home position of the lead screw 2, wherein the lead groove 2a and the recovery groove 3b as above described are connected via a lead-in groove 3c. Shanks 2g formed on both ends of the lead screw 2 are fitted into the bearing portion 1i of the load arm 1h in the chassis 1 and a bearing portion provided on the front side plate 1c, so as to bear thereon in free rotation. Note that the shanks 2g of the lead screw 2 are biased toward the thrust directions by leaf springs, not shown. Between the lead pulley 3a of the lead screw 2 and the recovery groove 3b, a clutch gear 4 is mounted integrally in the rotational direction, and slidably in the axial direction. The clutch gear 4 is urged toward the lead groove 2a by a clutch spring 5. The carrier 6 is slidingly mounted on the lead screw 2, and provided with a presser portion 6a for pressing an end face of the clutch gear 4, and a detector strip 6b for detecting a home position. A lead pin 7 is guided and supported in a guide hole (not shown) formed on the carrier 6 for the engagement with the lead groove 2a of the lead screw 2, and is biased into the lead groove 2a at a tip portion of a lead pin spring 8 attached to the carrier 6. A recording head 9 is mounted on the carrier 6, in which the recording head 9 as shown is a cartridge type integral with an ink tank, having a discharge port face 9a on which discharge ports 9c are formed and an ink tank portion 9b. The recording head 9 is an ink jet recording head for discharging ink by the use of the heat energy, comprising electricity-heat converters for generating the heat energy. Particularly, the ink jet recording head 9 as above described is one in which the recording is performed by discharging ink through discharge ports, by growth of bubble due to film boiling caused by the heat energy applied by the electricity-heat converters as above described. A carrier roller 10 is attached for free rotation on a front face of the carrier 6, and rotatably fitted into the long hole 1e on the chassis 1. The carrier motor 11, which is constituted of, for example, a pulse motor, bears on the chassis 1 by means of a pin 11a provided on a bottom portion thereof, and is mounted to be swingable in a direction as indicated by the arrow A around a bearing hole (not shown) of the chassis 11 bearing the pin 11a. Further, a spring shoe 11b is formed integrally with the carrier motor 11, which is urged in the direction A by a compression spring 14 attached between the spring shoe 11b and the lead arm 1h. A motor pulley 12 is secured on a motor shaft of the carrier motor 11, and a timing belt 13 is passed under tension between the motor pulley 12 and the lead pulley 3a secured onto the lead screw 2. The timing belt 13 is tensioned by a spring force of the compression spring 14. On the left side plate 1a of the chassis 1 is stood a set shaft 15 on which a blade lever 16 and a set lever 20 are rotatably mounted. Fig. 2 is a partial perspective view showing the blade lever 16 and the set lever 20 as above described. In Fig. 2, the blade lever 16 has a boss portion 16a rotatably mounted on the set shaft 15 (via a boss portion 20e of the set lever 20 in the example as shown). The set lever 20 is shaped like a bowed arm, with a top end of its arm portion 16b being formed with a hook portion 16c. In the neighborhood of the top end of the arm portion 16b rotatably bears a blade shaft 18, to which a wiping blade (wiper) 17 is secured. The wiper 17 is fabricated of an elastic material such as silicone rubber or CR rubber. At one end of the blade shaft 18 as above described, an engaging portion 18a with which the wiper 17 is driven for rotaton (wiping operation) is integrally formed. Immediately before an attaching portion for the wiper 17 in the arm portion 16b, an ink carrier 19, made of a hydrophilic porous material (plastic sintered compact, urethane foam, etc.), is mounted. The ink carrier 19 is to receive and absorb the ink from discharge ports 9c, when the recording head 9 is driven for predischarge at a position confronted to the ink carrier 19. Further before the arm portion 16b (almost intermediate portion in the example as shown), a long aperture 16d is formed. In the neighborhood of the boss portion of the set lever 20 are stood small arm portions 20a, 20b engaged by a cam portion of timing gear 21 (Figs. 1 and 3) as will be described later bearing on a shaft disposed parallel to the set shaft 15. A dowel 20d is provided in an intermediate portion of the set lever 20, and a hook portion 20c is formed in a top end of the set lever 20. If the set lever 20 is rotated in conjunction with the rotation of the timing bear 21 as will be described later, the hook portion 20c of the set lever 20 engages the engaging portion 18a of the blade shaft 18, and further, the dowel 20d of the set lever 20 fits into the long aperture 16d of the blade lever 16. Owing to the long aperture 16d, if the blade shaft 18 is rotated, the blade lever 16 is rotated around the set shaft 15, delayed by a predetermined time from the rotation of the set lever 20, so that a discharge port face 9a of the recording head 9 is wiped (wipe-over) by the movement of the wiper (wiping blade) 17 (in a direction as indicated by an arrow X in Fig. 4). Note that in the shown example, a rotation hole 20f of boss portion 20e in the set lever 20 is rotatably fitted onto the set shaft 15, the boss portion 16a (central portion for rotation) of blade lever 16 is rotatably fitted into the rotation hole 20f of the set lever 20, with each portion being rotated around the set shaft 15. On the chassis 1, a timing gear 21 engaged by a clutch gear 4 of the lead screw 2 is rotatably mounted around a shaft parallel thereto. Fig. 3 is a perspective view showing the timing gear 21. The timing gear 21 controls the timings for the rotation of the set lever 20 and the blade lever 16, and for the operation of a discharge recovery pump and a cap for enclosing a discharge port face, as will be described later. In Fig.3, around an external periphery of the timing gear 21, a blade cam 21a engaged by small arm portions 20a, 20b of the set lever 20, and driving teeth 21b some of which are omitted are formed. At a predetermined position of the timing gear 21, a cap cam A 21c and a cap cam B 21d for moving a cap lever 32 as will be described later, a piston get cam (end face cam) 21f for pressing a piston 28 of a pump (Fig. 8) as will be described later, and a piston reset cam 21g for resetting the piston 28 spaced by a predetermined distance from the piston set cam 21f are integrally formed. In Fig. 1, at a predetermined position in the neighborhood of a carrier home position of the chassis 1, an ink absorbing member spring 22 is attached, and at a top end thereof, an ink absorbing member 23 is attached which serves to pass the ink adhering to wiper (blade) 17, by the wiper 17 sliding in contact therewith. The ink absorbing member 23 is connected to at least one waste ink absorbing member 45 disposed in a space within the chassis 1, by way of ink transfer members 44 as will be described later. Fig. 4 is a partial perspective view showing an arrangement of a discharge port face 9a of recording head 9, a wiper 17, and an ink absorbing member 23, Fig. 5 is a typical partial perspective view showing an arrangement of the ink absorbing member 23, the ink transfer members 44a, 44b, and a waste ink absorbing member 45, Fig. 6 is a longitudinal cross-sectional view of Fig. 5, and Fig. 7 is a plan view of Fig. 5. The ink absorbing member spring 22 as above described is formed from a leaf spring of a predetermined length, fixed in a cantilevered state at its bottom portion 22 on the chassis 1, and a tap portion at which the ink absorbing member 23 is attached is able to deform elastically. An ink transfer member 44a is secured onto an upper face of the ink absorbing member spring 22 by adhesive or the like. The ink absorbing member 23 is fixed to a predetermined position in the state of abutting a front end portion of the ink transfer member 44a, by an absorbing member holding portion 22a formed on a front end portion of the ink absorbing member spring 22. On a surface of the carrier motor 11 on the left side plate 1a of the chassis 1, a waste ink absorbing member 45 is secured in a space between the left side plate 1a and the carrier motor 11, by adhesive or the like. Note that in the example as shown, a strip-like connection member 22b leading to the waste ink absorbing member 45 is connected at a trailing end portion of the ink absorbing member spring 22, and a second ink transfer member 44b, having one end contact with the ink transfer portion 44a and the other end contact with the waste ink absorbing member 45, is secured on a surface of the connection member 22b. Note that in the example as shown, the connection member 22b is connected twisted by approximately 90° with respect to the ink absorbing member spring 22, and the ink transfer members 44a, 44b are secured onto planar portions by adhesive or the like. The ink absorbing member 23 is fabricated of a hydrophilic porous material, like the ink carrier 19 as previously described (Fig. 2). The ink transfer members 44a, 44b and the waste ink absorbing member 45 are also fabricated of hydrophilic porous materials, for example, polyvinyl alcohol (PVA). The ink absorbing member 23, the ink transfer members 44a, 44b, and the waste ink absorbing member 45 can be fabricated of a same material with a superior ink absorbency. Thus, the ink imparted into the ink absorbing member 23 is transferred into the waste ink absorbing member 45, by the capillary action of the ink transfer members 44a, 44b, without saturating the ink absorbing member 23. The ink absorbing member 23 is formed with a wipe-over portion 23a of circular face with which the wiper 17 as previously described is brought into close contact, and in a lower portion thereof, further formed with an absorbing face 23b of circular surface for passing the ink adhering to the ink carrier 19 with which the ink carrier 19 as previously described (Fig. 2) for receiving predischarged ink is brought into close contact. Note that the absorbing member holding portion 22a of ink absorbing member spring 22 is urged upward by a slight amount of spring force, and made stationary at a predetermined position by a stopper, not shown. Thereby, when the wiper 17 and the ink carrier 19 are to be placed in close contact, the ink absorbing member 23 is always made contact by moving slightly downward with an elastic deformation of the ink absorbing member spring 22. Note that in this example, the ink transfer members 44a, 44b are connected in series, and the ink absorbing member 23 is connected to one waste ink absorbing member 45 so as to be able to transfer the ink, whereas with the ink transfer members 44 (generically showing 44a, 44b) connected in parallel or net as appropriate, the ink absorbing member 23 can be connected to a plurality of waste ink absorbing members 45 to be able to transfer the ink. Next, a recovery unit of ink jet recording apparatus as shown in Fig. 1 will be described in the following. Fig. 8 is an exploded perspective view showing a pump for recovering discharge as shown in Fig. 1, Fig. 9 is a perspective view of a piston unit as shown in Fig. 8, Fig. 10 is a longitudinal cross-sectional view of the pump as shown in Fig. 8, and Fig. 11 is a longitudinal cross-sectional view of the pump of Fig. 8, when a piston is located at an upper dead center. In Figs. 8 - 11, a cylinder 24 of pump comprises a cylinder portion 24a and a guide portion 24b for guiding a piston shaft 27, the guide portion 24b being formed with an ink flow path 24c consisting of an axial channel. The cylinder 24 has a cap lever carrier 24d projected therefrom, into which a lever seal 33 can fit, and an ink flow path 24e formed therein which opens to a predetermined position. Also, the cylinder 24 is integrally formed with a rotation lever 24f for receiving the rotation force (spring force) with a cap spring 43, in a direction where a cap 35 intimately encloses the discharge port face 9a. Further, at one end of the cylinder 24 is integrally formed a waste ink tube 24g inserted within the ink absorbing member 37 (Fig. 1) attached inside a feed roller 36 for conveying a recording medium 40. 24h indicates an ink flow path formed within the waste ink tube 24g as above mentioned. A piston seal 26 is fitted into an opening portion at other end of the cylinder 24, and outside thereof a cylinder cap 25 having a lever guide 25a is fitted by insertion under pressure. An internal diameter of the piston seal 26 is set at a slightly smaller dimension in order to obtain a predetermined pressure contact force against a peripheral face of the piston shaft 27. In order to reduce the sliding force of piston shaft 27, a lubrication coating may be applied on a surface of the piston seal 26. The piston shaft 27 is formed with an operation shaft 27a, a piston presser 27b, a piston carrier 27c, a connecting shaft 27d and a guide shaft 27c which are consecutive, and an axial channel 27f serving as an ink flow path leading to the ink flow path 24h. Note that the operation shaft 27a is formed with an axial channel 27g for preventing the rotation, and a bearing hole 27h is formed on a projection-side end portion of the operation shaft 27a. A piston 28 is slidably fitted into a cylinder portion 24a of the cylinder 24, where the piston 28 is made of a rubber material such as NBR, its outer diameter being formed slightly larger than an inner diameter of the cylinder portion 24a, and is adequately compressed when inserted into the cylinder portion 24a. A piston presser roller 29 and a piston return roller 30 are rotatably mounted via a roller shaft 31 on a projecting end portion (bearing hole 27h) of the piston shaft 27. On an upper side of the cylinder 24 is rotatably attached a cap lever 32 having its base ends carried by the cap lever carrier 24d and the lever guide 25a. The cap lever 32 is attached orthogonally to the cylinder 24. The cap lever 32 is carried by means of a rotation shaft 32a and an ink guide 32b projecting parallel to the cylinder 24 on both sides of its base ends. Also, on the base ends of the cap lever 32, a lever guide 32c having a guide opening guided into and engaged with the set shaft 15 is formed in projecting backward. Thus, the cap lever 32 is mounted for the approximate linear movement so as to enclose or uncover a discharge port face 9a of recording head 9 by rotation of the cylinder 24 around its shaft center. A convex spherical seal face 32d is provided on a top portion of the cap lever 32. Further, above and below the top portion of the cap lever 32, an engaging portion 32e engaged by a hook 34a of cap holder 34 is provided. An ink flow path 32f is formed inside the cap lever 32. The ink flow path 32f is formed to open to a central portion of the seal face 32d, passing through the inside of the lever 32, bent at right angles on the base ends of the lever 32, passing through a center of the ink guide 32b, and open to a top end face of the ink guide 32b. On a lower side of the ink guide 32b is formed a notch or communication aperture 32g loading to the ink flow path 32f. The ink guide 32b is fitted into a bottomed hole in the cap lever carrier 24d of the cylinder 24, a via a cylindrical lever seal 33 made of an elastic material such as a rubber. The lever seal 33 is fitted by pressure into both the ink guide 32b and the cap lever carrier 24d. The lever seal 33 is formed with a communication aperture 33a which communicates the notch 32g of the ink guide 32b with an ink flow path 24e formed almost radially in the cylinder 24. Therefore, the ink flow path 32f within the cap lever 32 communicates via the communication aperture 33a into the ink flow path 24e of the cylinder 24. The cap holder 34 is fixed on a top end portion of the cap lever 32, by means of engaging means composed of the hook 34a and the engaging portion 32e. At a central portion of the cap holder 34 is formed an opening 34b for attaching a cap 35. The cap 35, made of a rubber-like elastic material, is to prevent a normal ink from being dry, by enclosing a discharge port face 9a of the recording head 9 when not recording. A suction port 35a is formed within the cap35, and communicates via an ink flow path internally provided into an opening in a central portion at back side of the cap 35. At back side of the cap 35 is formed a flange portion for fixing the cap to the opening 34b of cap holder 34. In an assembled state where the cap 35 is attached to the cap holder 34, and the cap holder 34 is attached to the cap lever 32, a suction port 35a of the cap 35 is hermetically communicable to the ink flow path 32f of cap lever 32 opening to the seal face 32d. Returning to Fig. 1, a feed roller 36 for conveying a recording medium 40 is one in which, for example, an elastic coating (e.g., urethane resin) is applied on a surface of aluminum drawn tube. A waste ink absorbing member 37 is attached inside the feed roller 36. The waste ink absorbing member 37 is one made by filling an absorbing material of polyester cotton or the like into a plastic cylindrical case of polyethylene or EVA, with a better ink absorbency in the axial direction. The waste ink absorbing member 37 has the waste ink tube 24g of the cylinder 24 inserted and fixed therein, whereby waste ink exhausted from the pump is introduced into the waste ink absorbing member 37. The chassis 1 has a paper presser plate 38 mounted to closely press a recording medium 40 onto a peripheral face of the feed roller 36. The feed roller 36 is controlled and driven via a reduction gear of a predetermined ratio by a paper feed motor 39. At a predetermined position of the chassis 1, a home position detector 41 consisting of a transparent-type photointerrupter is installed, thereby enabling the detection of a home position of the carrier 6 with a detection stripe 6b intercepting a light path. Note that numeral 42 in Figs 10 and 11 indicates a pump chamber of recovery pump. Next, the operation of an ink jet recording apparatus with the above constitution will be described. First, in a normal recording operation, the lead screw 2 is rotated via the timing belt 13 by rotation of the carrier motor 11, and the carrier 6 is moved for scan in the recording column direction via the lead pin 7 engaging the lead groove 2a of lead screw 2. The carrier motor 11 is urged in the arrow A direction by the motor spring 14, so that the timing belt 13 is always tensioned. Though inertial force is exerted in moving, starting or stopping the carrier 6, the load of motor spring 14 and the motor load can be sufficient with the lesser amounts because the weight of carrier motor 11 generates an inertia. If an air or hydraulic damper is provided on a part of the motor spring 14, noise owing to the vibration of motor rotor in starting or stopping the carrier 6 can be reduced. Note that an overshoot of motor 11 can be reduced by appropriately selecting the weights of motor 11 and carrier 6, and the damping coefficient of motor spring 14, so that the noise can be lowered. In the discharge recovery operation, first, the carrier 6 is moved in the direction to a home position (direction as indicated by an arrow B) until the home position detector 41 detects a predischarge position immediately before the home position, and if detected, the ink is predischarged to discharge some slightly thickened ink with a discharge force of recording head 9 for the recovery operation. Note that at the predischarge position as above indicated, the lead pin 7 still engages the lead groove 2a, with discharge ports 9c being opposed to the ink carrier 19 (Fig. 2). Periodical predischarges performed during normal recording to remove thickened ink around discharge ports 9c not discharging ink are also carried out at the predischarge position. If the carrier 6 is moved in the arrow B direction by further rotating the lead screw 2, the presser portion 6a presses against the clutch gear 4, which thus moves in the arrow B direction, and mates with a driving gear 21b (Fig. 3) of the timing gear 21. The clutch gear 4 is rotated synchronously with the lead screw 2, the timing gear 21 is rotated in the arrow D direction (Figs. 1 and 3) by the lead screw 2 rotating in the arrow C direction. On the other hand, as the lead pin 7 passes through the lead-in groove 3c into the recovery groove 3b orthogonally disposed at a position where the clutch gear 4 and the timing gear 21 mate with each other, the rotation of lead screw 2 will not move the carrier 6. If the timing gear 21 is rotated in the arrow D direction, the set lever 20 is rotated in the arrow E direction (Fig. 2), because the blade cam 21a of the timing gear 21 engages between small arm portions 20a, 20b of the set lever 20. At this time, as the hook portion 16c of blade lever 16 (Fig. 2) engages a click portion of chassis 1, and the dowel 20d of set lever 20 fits into a long aperture 16d of blade lever 16 with a backlash, the rotational force is not immediately transmitted to the blade lever, whereby the set lever 20 only is rotated at early time with the blade lever 16 stopped. On the other hand, as the hook portion 21c of set lever 20 engages an engaging portion 18a of blade shaft 18 bearing on the blade lever 16, early rotation of the set lever 20 causes the blade shaft 18 to be lowered down in the arrow F direction, with the wiper (blade) 17 secured thereto being rotated in the G direction to be set at a wiping position. With the set lever 20 being rotated by a predetermined amount, the engagement between the hook portion 16c and the click portion of chassis 1 is released, and the dowel 20d is brought into contact with an end portion of the long aperture 16d, whereby the set lever 20 and the blade lever 16 are integrally rotated. Thus, with the timing gear 21 being further rotated in the D direction, the blade lever 16 as well as the set lever 20 is rotated in the arrow E direction, with the wiper 17 moving in the arrow X direction as shown in Fig. 4 to wipe and clean (wiping) a discharge port face 9s of recording head 9. With a further rotation, the wiper 17 slides in contact with a wipe-over portion 23a of the ink absorbing member 23 carried by the ink absorbing member spring 22 at a predetermined position of chassis 1, whereby ink, water droplets, and contaminants adhering to the wiper 17 are imparted to the ink absorbing member 23. Thus, foreign matters such as ink, water droplets and contaminants which are wiped away from the discharge port face 9a are imparted to the ink absorbing member 23, and the wiper 17 itself is again cleaned. Further, as the ink carrier 19 also slides in contact with an absorbing face 23 of ink absorbing member 23, ink or other matters existent thereon which may drop from the wiper 17 and adhere to the ink carrier 19 are imparted to the ink absorbing member 23 as well. Ink or water droplets adhering to the ink absorbing ember 23 are transferred from the ink absorbing member 23 through the ink transfer members 44a, 44b into the waste ink absorbing member 45 disposed in a desired space of chassis 1, due to the capillary action. Therefore, even when a comparatively small volume of ink absorbing member 23 is used, a period during which it is saturated with ink or water content can be largely lengthened. If the timing gear 21 is rotated in the arrow D direction, the engagement between the small arm portions 20a, 20b of set lever 20 and the blade cam 21a of timing gear 21 is disengaged, so that the small arm portion, 20a, 20b can move along an external periphery of the blade cam 21a, and the rotation of timing gear 21 is not transmitted to the set lever 20. Accordingly, the set lever 20 and the blade lever 16 are released from the timing gear. Subsequently, with a further rotation of the timing gear 21, the cap 35 is stopped first at a position away fro the recording head 9, because the cap cam A 21c restricts a rotation click 25b (Fig, 8) of cylinder cap 25 (Figs. 8, 10 and 11). Subsequently, with a further rotation of the timing gear 21 in the arrow D direction, as the cap cam A 21c leaves the rotation clock 25b, the cylinder 24 is rotated in the arrow G direction (Fig. 8) due to a biasing force of cap spring 43 tensioned between the chassis 1 and the rotation lever 24f of cylinder 24, and the cap lever 32 driven with the rotation of the cylinder 24 moves toward the discharge port face 9a, thereby causing the cap 35 to enclose the discharge port face 9a. Thus, the capping operation of recording head 9 can be completed. The above operations are cleaning (wiping) and capping operations, and normally, the operation stops here to wait for a next record start signal. If the next record start signal is issued, the reverse operations as above described are performed to enter the recording operation. On the other hand, if a rotation operation signal is issued in a waiting state as above mentioned, the suction operation with the pump is entered. Next, the pump operation will be explained. First, with a rotation of timing gear 21, as the piston set cam 21f (Fig. 3) pressed the piston presser roller 29 (Figs. 8 - 11) mounted on the piston shaft 27, the piston shaft 27 moves in the arrow H direction. With this movement of piston shaft 27, the piston 28 is also pressed to move in the arrow H direction, thereby causing the inside of pump chamber 42 to have a negative pressure. In this case, the ink flow path 24e of cylinder 24 opens to the cylinder portion 24a until a rib 28d of the piston 28 on the piston 28 on the piston shaft 27 reaches, communicating through the ink flow path 24h and the groove 27f, so that the negative pressure within the pump chamber 42 only increases, with the piston 28 being movable. On the other hand, after the piston shaft 27 is further forced in so that the piston rib 28d in contact with the cylinder portion 24a passes the ink flow path 24c, the ink flow path 24e opens again, and the ink from the recording head 9 is sucked via a suction port 35a. The ink sucked hereby passes through the ink flow path 32f within cap lever 32, through the communicating aperture 33a of lever seal 33 and the like flow path 24e of cylinder 24 into the pump chamber 42. With a further rotation of timing gear 21, the rotation shaft 32a of cap lever 32 is moved backward slightly with the cap cam B 21d (Fig. 3), the cap 35 is separated away from the discharge port face 9a slightly, to eliminate residual ink by sucking the ink on the discharge port face 9a and within the suction cap 35 by the use of a residual negative pressure of pump chamber 42. Next, if the timing gear 21 is rotated reversely (direction as indicated by an arrow I in Fig. 3), the piston reset cam 21g pulls the piston return roller 30 (Fig. 8) so as to move the piston shaft 27 in the arrow J direction. At this time, the piston 28 moves after the piston carrier 27c on the piston shaft 27 makes contact therewith, a clearance Δl is generated between an end face 28h of piston 28 and the piston presser 27b. With the movement of piston shaft 27 and piston 28 in the arrow J direction, waste ink sucked within the pump chamber 42 passes through the clearance Δl, further passing through the groove 27f of piston shaft 27, ink flow path 24c of cylinder 24, and ink flow path within waste ink tube 24g, and exhausted into a near central portion of waste ink absorbing member 37 attached to the inside of feed roller 36. An embodiment for resolving a phenomenon where waste ink once sucked flows backward, which is a technical problem associated with a conventional pump and ink absorbing system, will be described in the following. Referring now to Fig. 13, a plurality of opening portions 112a - 112n (total 14 in the present embodiment) is provided on a peripheral wall of coating member 112 within a conveying roller for conveying platen roller or a recording medium, wherein opening portions 112a - 112n, which are circular and have the same opening areas, are arranged in two rows parallel to the axial direction of coating member 112, in such a manner that intervals between adjacent ones are widen from a left side of waste ink absorbing member 108 as shown where waste ink absorption is started to a right upward side as shown. Next, another embodiment will be explained. In Fig. 14, around a peripheral wall of coating member 122, a plurality of circular opening portions 122a - 122g (seven in the present embodiment) having different opening areas are arranged in a row parallel to the axial direction of the coating portion 122, wherein the opening areas of opening portions 122a - 122g are smaller when going away from a side of waste ink absorbing member 128 where waste ink absorption is started. Opening portions provided on the coating members as shown in two embodiments as above described are all circular aperture having an advantage of being easily fabricated. The shape, number and positions of opening portions are not limited to those as shown in the embodiments as above described, but any opening portions communicating the waste ink absorbing member 128 to the atmosphere can be used. Next, other embodiment will be described. In Fig. 15, a plurality of waste ink absorbing members 138a - 138d (four in this embodiment), which are cylindrical and have the same outer diameter, are coated by cylindrical coating members 132a - 132d having both ends opened while leaving circumferential strip-like exposed portions 139a - 139f on both edges of the circumferential faces, respectively, for communicating waste ink absorbing member 128 to the atmosphere, with respect expose end faces being made contact and connected in the axial direction. However, an end face exposed n the right side of waste ink absorbing member 138d located rightmost as shown is aligned with an opening end of coating member 132d, while within the waste ink absorbing member 138a located leftmost as shown, a waste ink tube 137a connected to the pump unit, not shown, has been inserted by an appropriate length. The coating members 132a - 132d are secured on a holding member 131 having both ends fixed onto a second side plate (not shown) provided on the pump unit and chassis, whereby the waste ink absorbing members 138a - 138d are supported. However, the coating member 132d located at right end portion as shown is fixed to the second side plate as well as the holding member 131, while the coating member 132a located at left end as shown is fixed to the pump unit. While in the present embodiment, four waste ink absorbing members 138a - 138d are connected, any appropriate number of connections can be used according to the size of an ink jet recording apparatus. The coating members as shown in aforementioned three embodiments are all fixed, but they can be constituted to be rotatable along with roller for conveying a recording medium. According to the described embodiments, the waste ink absorbing member 108 is communicated to the atmosphere at multiple places through a plurality of opening portions provided on peripheral wall of coating member 112, so that the flow of waste ink within the waste ink absorbing member 108 due to reciprocation of piston can be made smoother. Further, these opening portions have an effect of promoting the evaporation of waste ink absorbed into the waste ink absorbing member 108. A further embodiment for resolving a phenomenon where waste ink flows backward will be described in the following. Fig. 16A is a cross-sectional view of a suction pump according to an embodiment of the present invention. In the figure, a waste ink tube 224g of cylinder 224 is inserted into the waste ink absorbing member 237 by its length l 1 . The waste ink absorbing member 237 is an absorbing member of polyester fibers aligned horizontally, and inserting the waste ink tube 224g as previously described will not be cause the absorbing member 237 to be entered into the ink flow path 224h. Accordingly, in the present embodiment, the ink is always absorbed into the absorbing member 244 within cylinder and carried thereon by embedding the absorbing member 244 within cylinder into the ink flow path 224h, without leaving the ink only within the ink flow path 224h. The ink carried on the absorbing member will migrate to the waste ink absorbing member 237, because an end face of the absorbing member 244 within cylinder and the waste ink absorbing member 237 are closely contact. Thereby, the absorbing member 244 within cylinder is always placed in a state of absorbing ink without being saturated with ink. In the present embodiment, the opening operation of cap 35 for the recording head 9 is carried out against the tension of cap spring, not shown, and the closing operation is performed with the tension of cap spring. Then, as the pressure contact force of cap 35 against the discharge port face of recording head 9 is decreased by the amount of a sliding resistance due to the sliding between a surface of waste ink tube 224g and waste ink absorbing member 237, the waste ink tube 224g of cylinder 224 is of a stepped-shape to reduce the gliding resistance as much as possible. In the present embodiment, as the waste ink tube 224g of cylinder 224 is stepped as above described, the ink may remain on that portion. Thereby, to remove the ink, as shown in Fig. 16B, which is a cross-sectional view taken along a line K-K in Fig. 16A, a V-groove 224i is provided to move the ink staying in that step portion to the absorbing member 244 within cylinder, with the capillary action of ink in that groove 224i. Thereby, even if there is any step within the cylinder, the ink will not stay on the step portion. Note that in the present embodiment, in order to be substantially in communication with the atmosphere during the capping, as shown in Fig. 16C which is a view according to the direction of the arrow L of Fig. 16A, a rib 224j is provided to form a clearance 224l within the ink flow path 244h even if the absorbing member 244 within cylinder is embedded. A material of absorbing member 244 within cylinder is inexpensive melamine foaming body, continuous foam. Fig. 17A is a cross-sectional view of a suction pump according to another embodiment of the present invention. In this embodiment, a waste ink tube 224g of cylinder 224 is not stepped, but of a straight shape. In this case, as the waste ink tube 224g is not stepped, the ink will not stay within the cylinder 224. Also in this case, as shown in Fig. 17B, which is a view according to the direction of the arrow M of Fig. 17A, like previous embodiments, as a clearance 224l is provided by a rib 224j of waste ink tube 224g, the inside of pump is substantially in communication with the atmosphere even during the caping. Fig. 18 is a cross-sectional view of a suction pump according to another embodiment of the present invention. As shown in the same figure, waste ink absorbing member 237 has a part 237a projected therefrom, and inserted into a cylinder flow path 224h, with the absorbing member 244 within cylinder and the waste ink absorbing member 237 being integrally formed. According to the embodiments as above described, a conventional problem that the ink is liable to fix at a position of an end face 244a of absorbing member 244 within cylinder, and waste ink is not absorbed smoothly into waste ink absorbing member 237 could be eliminated. That is, by providing an absorbing member within the cylinder, the above-mentioned phenomenon was resolved by making smoother the flow of waste ink passing from the absorbing member within cylinder maintained in a constant humidity condition to the waste ink absorbing member, with the capillary action of ink. Thereby, as waste ink is absorbed smoothly into the waste ink absorbing member and evaporated, a problem of ink backflow as previously described could be resolved. In the embodiments as above described, waste ink tubes 224g, 324g are both substantially in communication with the atmosphere. By communicating the waste ink tubes to the cap 35 even during the capping of recording head, the inside of cap could be substantially in communication with the atmosphere during the capping. With this constitution, an embodiment of the mechanism for preventing the meniscus from being depressed at the capping will be described in the following. Fig. 19 shows a state during the capping where a piston 328 reaches an upper dead center in the embodiment of the present invention. A rib portion 328d of piston 328 totally opens without closing an ink flow path 324e of cylinder 324. The placement of the piston rib portion 328d at this position is made possible by changing a cam lift diagram for a piston set cam 321f of timing gear 321 or piston reset cam 321g. When a waste ink tube 324g of cylinder 324 opens totally to the atmosphere, the inside of cap is not pressed at all even if cap 325 may deform. But in this state, the feature of preventing undischarge of ink due to fixing of ink in a nozzle 9c of recording head 9 is not achieved at all. Accordingly, in this embodiment, since an end portion of waste ink tube 324g within cylinder 324 has been inserted into a waste ink absorbing member 337 with certain gas permeability, the inside of cap 35 during the capping is substantially in communication with the atmosphere, and is not pressed even if the cap may deform, whereby the ink meniscus in the recording head 9 will not flow back into a tank portion 9b to break the meniscus and make the recording impossible. As waste ink has been absorbed into the waste ink absorbing member 337, the inside of cap is wetted adequately with ink, so that the nozzle 9c of recording head 9 may not have ink fixed. Fig. 20 shows another embodiment of the present invention, in which an object of the present invention can be accomplished by using a conventional timing gear 21 and with the exact same software control. That is a constitution in which a hole 328l provided in a rib 328b of piston 328 is made in communication with the inside of cylinder 324. With this constitution, it is substantially in communication with the atmosphere through a hole 328e of piston 328 during the capping. According to the example of an ink jet recording apparatus as above described, waste ink absorbing member 45 is appropriately disposed by using a clearance within the ink jet recording apparatus, and an ink absorbing member 23 for absorbing the ink wiped over by wiper 17 for cleaning a discharge port face 9a of recording head 9 and the waste ink absorbing member 45 are connected by means of ink transfer members 44a, 44b, so that the ink can be delivered into the waste ink absorbing member using the capillary action of ink within the ink transfer members 44a, 44b, whereby a period of being saturated with ink in the ink absorbing member 23 can be greatly increased without increasing a volume of the ink absorbing member 23, and thus, the ink absorbent capability can be significantly improved. Further, as waste ink can be evaporated from a surface of such continuous absorbing members, a waste ink backflow problem could be resolved by decreasing the amount of suction for a suction pump itself to increase the evaporation efficiency of waste ink absorbed by the pump. As the waste ink absorbing member 45 as above described is fixedly disposed using adhesive or the like in a space within recording apparatus, it can be disposed freely in accordance with the space, for example, by making the sheet-like shape, without any limitation of volume or number thereof, whereby an ink jet recording apparatus in which the waste ink absorbent ability is very high and thereby the number of sheets to be recorded is greatly increased can be obtained with a simple structure and without losing the compactness of recording apparatus. Note that the ink transfer members 44a, 44b are used to transfer the ink, and sufficiently effective even with a small cross section (e.g., a thickness of 1 mm), and the bridging function of ink can be fully exhibited even at a narrow place. Fig. 12 is a typical view showing an arrangement example where a plurality of waste ink absorbing members 45 (four in the example as shown) are connected by ink transfer members 44, for a single ink absorbing member 23. In this way, with the provision of a plurality of waste ink absorbing members 45, the ink absorbent ability of an ink absorbing member 23 can be further easily improved by the effective use of an internal space within recording apparatus. Note that the example as previously described shows a case where a cartridge-type recording head 9 integral with an ink tank 9b is used as a recording head, whereas the present invention is not limited to this one, but is also applicable to a case of using a recording head of the type without almost requiring the exchange, and can provide the same effect. In the example as above mentioned, the present invention is explained by illustrating an ink jet recording apparatus of the serial-scan type having a recording head 9 mounted on carrier 6, whereas the present invention is also applicabel to an ink jet recording apparatus with the other recording method, such as a line-type ink jet recording apparatus using a line-type recording head which covers a recording area in the paper-width direction of recording medium, and the same operation effect can be achieved. The present invention is also effective irrespective of the number of recording heads. The present invention brings about excellent effects particularly in an ink jet recording apparatus having an ink jet recording head of the ink jet system for recording by forming fine liquid droplets with that heat energy among the various ink jet recording systems. As to its representative constitution and principle, for example, one practiced by use of the basic principle disclosed in, for example, U.S. Patents 4,723,129 and 4,740,796 is preferred. This system is applicable to either of the so-called on-demand type and the continuous type. Particularly, the case of the on-demand type is effective because, by applying at least one driving signal which gives rapid temperature elevation exceeding nucleus boiling corresponding to the recording information on electricity-heat converters arranged corresponding to the sheets or liquid channels holding a liquid (ink), heat energy is generated at the electricity-heat converters to effect film boiling at the heat acting surface of the recording head, and consequently the bubbles within the liquid (ink) can be formed corresponding one by one to the driving signals. By discharging the liquid (ink) though an opening for discharging by growth and shrinkage of the bubble, at least one droplet is formed. By making the driving signals into pulse shapes, growth and shrinkage of the bubble can be effected instantly and adequately to accomplish more preferably discharging of the liquid (ink) particularly excellent in response characteristic. As the driving signals of such pulse shape, those as disclosed in U.S. Patents 4,463,359 and 4,345,262 are suitable. Further excellent recording can be performed by employment of the conditions described in U.S. Patent 4,313,124 of the invention concerning the temperature elevation rate of the above-mentioned heat acting surface. As the constitution of the recording head, in addition to the combination of the discharging orifice, liquid channel, and electricity-heat converter (linear liquid channel or right-angled liquid channel) as disclosed in the above-mentioned respective specifications, the constitution by use of U.S. Patent 4,558,333, or 4,459,600 disclosing the constitution having the heat acting portion arranged in the flexed region is also included in the present invention. In addition, the present invention can be also effectively made the constitution as disclosed in Japanese Laid-Open patent Application No. 59-123670 which discloses the constitution using a slit common to a plurality of electricity-heat converters as the discharging portion of the electricity-heat converter or Japanese Laid-Open Patent Applicatio No. 59-138461 which discloses the constitution having the opening for absorbing pressure wave of heat energy correspondent to the discharging portion. Further, as the recording head of the full line type having a length corresponding to the maximum width of a recording medium which can be recorded by the recording device, either the constitution which satisfies its length by a combination of a plurality of recording heads as disclosed in the above-mentioned specifications or the constitution as one recording head integrally formed may be used, and the present invention can exhibit the effects as described above further effectively. In addition, the present invention is effective for a recording head of the freely exchangeable chip type which enables electrical connection to the main device or supply of ink from the main device by being mounted on the main device, or a recording head of the cartridge type having an ink tank integrally provided on the recording head itself. Also, addition of a restoration means for the recording head, a preliminary auxiliary means, etc. provided as the constitution of the recording device of the present invention is preferable, because the effect of the present invention can be further stabilized. Specific examples of these may include, electricity-heat converters or another type of heating elements, or preliminary heating means according to a combination of these, and it is also effective for performing stable recording to perform preliminary mode which performs discharging separate from recording. Further, as the recording mode of the recording device, the present invention is extremely effective for not only the recording mode only of a primary color such as black etc., but also a device equipped with at least one of plural different colors or full color by color mixing, whether the recording head may be either integrally constituted or combined in plural number. Further, a recording apparatus according to the present invention is provided integrally or separately as an image output terminal for an information processing equipment such as a word processor or computer, a copying machine in combination with a reader, or a facsimile terminal equipment having the transmission and reception feature. According to the present invention, with a feature of preventing the ink within pump from a suction portion of pump to the outside of pump, an ink jet recording apparatus and a pump mechanism for use therewith which can prevent the ink from flowing backward to sucked member can be obtained. According to the present invention, an ink jet recording apparatus and a pump mechanism for use therewith in which ink meniscus is not depressed can be obtained.

Claims: A pump mechanism for an ink jet recording apparatus, said pump mechanism comprising: a pump having a suction portion (27, 27a, 42) for sucking from a sucked member (35), said pump having no valve associated with said suction portion (27, 27a, 42) to perform suction; an exhaust member (36) for exhausting waste ink from said pump, said exhaust member (36) being connected to said pump via a waste ink guiding member (24g, 224g, 324g); a prevention means for preventing a backflow of ink within said pump from said suction portion (27, 27a, 42) of said pump to the outside of said pump due to a suction operation by said suction portion (27, 27a, 42), wherein said prevention means comprises a waste ink absorbing member (224, 237a) which is provided at a portion of said waste ink guiding member (24g, 224g, 324g). A pump mechanism for an ink jet recording apparatus according to claim 1, wherein said waste ink guiding member (24g, 224g, 324g) is a waste ink tube and said waste ink absorbing member (224, 237a, 37) is inside said waste ink tube and inside said exhaust member (36). A pump mechanism for an ink jet recording apparatus according to claim 1 or 2, wherein said waste ink absorbing member (37) is opened to the atmosphere. A pump mechanism for an ink jet recording apparatus according to any of the preceding claims, wherein said sucked member is a cap (35) for enclosing a discharge port of an ink jet recording head (9), and wherein said prevention means is formed as an incomplete communicating path by using means having liquid absorbing properties as well as air permeating properties, so that the inside of said cap (35) is substantially in communication with the atmosphere via the inside of said pump. A pump mechanism for an ink jet recording apparatus according to claim 1 or 4, wherein said waste ink guiding member (24g, 224g, 324g) of said pump is embedded and carried in said waste ink absorbing member (37). An ink jet recording apparatus comprising: a recording head for recording onto a recording member; and a pump mechanism according to any of the preceding claims 1 to 5. An ink jet recording apparatus according to claim 6, further comprising a waste ink absorbing member for absorbing the ink adhering to a cleaning member (17) for cleaning a discharge port face of said recording head (9), said absorbing member being formed by a plurality of consecutive absorbing members (23, 44, 45). An ink jet recording apparatus according to claim 7, wherein said consecutive absorbing members (23, 44, 45) have a larger surface area in the absorbing member (45) farthest from said cleaning member (17) than in the absorbing member (23) nearest to said cleaning member (17). An ink jet recording apparatus according to claim 6, wherein an exhaust member (36) is formed by a conveying roller for conveying said recording medium (40) to a recording area, and said waste ink absorbing member (37, 108, 128, 138, 237) is provided for communicating with the atmosphere through a plurality of opening portions (112, 122, 139) inside said conveying roller. An ink jet recording apparatus according to claim 6, wherein said recording head has electricity-heat converters, and discharges the ink through said discharge ports (9c) by growth of bubbles due to film boiling caused by the heat energy generated by said electricity-heat converters. An ink jet recording apparatus according to claim 6, wherein said pump has a piston (28, 228, 328) which can communicate said pump to the inside of said cap (35) while said cap encloses said discharge port face.

Inventors: ARA YOJI, IKADO MASAHARU, ARA, YOJI, IKADO, MASAHARU, ARA, YOJI, CANON KABUSHIKI KAISHA, IKADO, MASAHARU, CANON KABUSHIKI KAISHA
Applicants: CANON KK, CANON KABUSHIKI KAISHA
Application year: 1991
Main classification: B41J2
IPC codes: B41J2