Ink jet recording apparatus and cap for such apparatus

Abstract: The present invention provides an ink jet recording apparatus comprising a cap member (6b) capable of sealing a discharge port for discharging ink and being provided at its bottom with an ink suction opening (6c) and an atmosphere communicating opening (6d), an ink absorbing member (20) disposed within the cap member (6b), a suction pump (11-14) communicated with the ink suction opening, and an atmosphere communicating valve (17) communicated with the atmosphere communicating opening (6d), and wherein areas of the ink absorbing member (20) opposed to the ink suction opening (6c) and the atmosphere communicating opening (6d) are thinner than the other area and the ink absorbing member (20) abuts against the ink suction opening.

Description: BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to an ink jet recording apparatus for effecting recording on a recording medium by discharging ink from a recording means, and a cap for such an apparatus. The present invention can be applied to an apparatus such as a printer, a copying machine, a facsimile having a communication system or a word processor having a printer portion for effecting recording on a recording medium such as a paper sheet, thread, fibers, cloth leather, metal, plastic, glass, wood or ceramics and to an industrial recording apparatus in which various processing devices are combined in a composite manner. Here, the word "recording" means not only to afford an image such as characters or figures which are meaningful to a recording medium but also to afford an image such as a pattern which is meaningless to a recording medium. Related Background Art An ink jet recording system has been used with printers and copying machines because of low noise, low running cost, easiness of compactness and easiness of colorization. In the past, in ink jet recording apparatus, for the purpose of preventing ink clogging of discharge ports of a recording head due to solidification of ink or increase in ink viscosity caused by the drying of ink, the discharge ports of the recording head have been shielded from atmosphere, or, for the purpose of recovering clogging of discharge ports due to solidification of ink or increase in ink viscosity or bubbles or foreign matters generated in liquid passages, a suction recovering operation for forcibly discharging ink by generating pressure at the discharge openings has been performed. For example, as an example of such a suction recovering operation, a cap member is closely contacted with a discharge port surface of a recording head and ink is sucked from the recording head by generating negative pressure within the cap member and thereafter the ink remaining in the cap is sucked (idle suction) by communicating the interior of the cap with the atmosphere. Further, as another example, in order to prevent scattering of ink from the cap to the discharge ports of the recording head during the suction and to such the ink remaining around the discharge ports of the recording head, an ink absorbing member made of porous material for absorbing the ink is disposed within the cap member. However, recently, in the ink jet recording systems, high quality recorded images have been requested and improvement in water-resistance and light-resistance of ink has been made. For example, various inks such as ink which becomes water-soluble (to water) after drying or ink including pigment as coloring agent have been used. Some of such inks increases its viscosity to loose fluidity (for example, becomes gel) after it is dried due to vaporization. After an image was printed on a recording sheet by using the recording head utilizing the above-mentioned ink, if next recording is not effected for a long term, i..e, if the discharge ports of the recording head are kept in the sealed condition by the cap for a long term, small amount of ink remaining in the ink absorbing member after the previous suction recovery may be solidified in the ink absorbing member or may cause clogging. As a result, even when the suction recovery is effected to prepare for next recording, predetermined pressure does not act on the recording head not to suck the ink from the recording head sufficiently or the interior of the cap becomes hard to be communicated with the atmosphere not to achieve the suction of ink (idle suction), thereby not realizing the normal or optimum suction recovery. EP 0 744 294 shows an ink jet apparatus according to the preamble of claim 1 and a cap according to the preamble of claim 9. SUMMARY OF THE INVENTION An object of the present invention is to provide an ink jet recording apparatus and a cap for such an apparatus, in which, even when discharge ports of a recording head are sealed for a long term, a recovering operation for the recording head can surely be effected. Another object of the present invention is to provide an ink jet recording apparatus comprising a cap member capable of sealing discharge ports of a recording head and being provided at its bottom with an ink suction opening and an atmosphere communicating opening, an ink absorbing member disposed within the cap member, a suction pump communicated with the ink suction opening, and an atmosphere opening valve communicated with the atmosphere communicating opening, and wherein areas of the ink absorbing member opposed to the ink suction opening and the atmosphere communicating opening are thinner than the other area and the ink absorbing member abuts against the ink suction opening. A further object of the present invention is to provide a cap for an ink jet recording apparatus comprising a cap member capable of sealing discharge ports of a recording head and being provided at its bottom with an ink suction opening for communication with a suction pump and an atmosphere communicating opening for communication with an atmosphere opening valve, and an ink absorbing member disposed within the cap member, and wherein areas of the ink absorbing member opposed to the ink suction opening and the atmosphere communicating opening are thinner than the other area and the ink absorbing member abuts against the ink suction opening. In the present invention, when ink is sucked from the recording head, an amount of ink remaining in the ink absorbing member can be reduced. Even when the apparats is left as it is for a long term without recording, occurrence of ink solidification and clogging of the ink absorbing member can be reduced. If ink solidification or clogging should be partially generated in the ink absorbing member, after the ink starts to flow once, solidified or clogged ink becomes apt to be solved again from the thinner area of the ink absorbing member. Further, after the ink suction from the recording head, when the interior of the cap member is communicated with the atmosphere, the atmosphere can easily be communicated with the interior of the ink absorbing member, thereby effecting the suction of the residual ink (idle suction) positively. As a result, the recovering operation for the recording head can be effected positively. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view showing the entire construction of an ink jet recording apparatus according to a first embodiment of the present invention: Fig. 2 is a perspective view showing a carriage of Fig. 1 and a recovering unit for a recording head mounted on the carriage; Fig. 3 is a perspective view showing the entire construction of the recovering unit of Fig. 2; Fig. 4 is a sectional view showing a main portion of the recovering unit of Fig. 2; Fig. 5 is a sectional view showing a main portion of the recovering unit of Fig. 2; Fig. 6 is a schematic side view of the recovering unit of Fig. 2; Fig. 7 is an explanatory view for explaining a recovering operation of the recovering unit of Fig. 2; Fig. 8 is a top view of a cap in the recovering unit of Fig. 2; Fig. 9 is a sectional view taken along the line 9 - 9 in Fig. 8; Fig. 10 is a top view of a cap in a recovering unit of an ink jet recording apparatus according to a second embodiment of the present invention; Fig. 11 is a sectional view taken along the line 11 - 11 in Fig. 10; and Fig. 12 is a sectional perspective view showing an ink jet recording head available to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be explained in connection with embodiments thereof with reference to the accompanying drawings. [First embodiment] Fig. 1 is a perspective view showing the entire construction of an ink jet recording apparatus according to a first embodiment of the present invention, Fig. 2 is a perspective view showing a carriage of Fig. 1 and a recovering unit for a recording head mounted on the carriage, and Fig. 3 is a perspective view showing the entire construction of the recovering unit of Fig. 2. Figs. 4 and 5 are sectional views showing a main portion of the recovering unit of Fig. 2, Fig. 6 is a schematic side view of the recovering unit of Fig. 2, Fig. 7 is an explanatory view for explaining a recovering operation of the recovering unit of Fig. 2, Fig. 8 is a top view of a cap in the recovering unit of Fig. 2, and Fig. 9 is a sectional view taken along the line 9 - 9 in Fig. 8. First of all, a fundamental construction of the recording apparatus according to the first embodiment. In Figs. 1 to 3, a carriage 2 can be shifted along a guide shaft 101 in a main scanning direction perpendicular to a recording sheet conveying direction. The carriage 2 is mounted on the guide shaft 101 by inserting a bearing 100 at a rear part of the carriage onto the guide shaft. Two heads of different type are mounted on the carriage 2, and such two heads are deviated from each other, for example by about 4 mm, in the recording sheet conveying direction. One of two heads is a photo-head 111 having tanks for magenta and cyan inks having low density and an ink tank for black ink, and a color head 112 capable of discharging yellow, magenta and cyan inks. By combination of these heads, the recording apparatus can effect printing with six color inks, thereby permitting sharp photograph like printing. Alternatively, by replacing the photo-head 111 by a black head having only an ink tank for black color, text printing can be effected at a high speed or business color can be printed at a high speed. Further, the ink jet recording apparatus is provided with a recovery base 12 having a cap slider 8 (Fig. 3) for capping two heads mounted on the carriage 2 to effect recovering treatment, which recovery base is located at a predetermined position within a main body of the apparatus near a right side thereof (near the arrow A2). As shown in Figs. 2 and 3, the cap slider 8 on the recovery base 12 can be slidingly shifted together with the carriage 2 when a projection 8a of the slider is pushed by the moving carriage 2. The cap slider 8 is provided with a cap holder 7 holding caps 6a, 6b for covering discharge port forming surfaces of two recording heads 111, 112. The cap holder 7 can be shifted in the direction A2 while being lifted, with the result that the discharge port forming surfaces of the recording heads 111, 112 are capped by the caps 6a, 6b. Further, there is provided a suction pump (recovery treating means) 11 for generating negative pressure in the caps 6a, 6b contacted with two recording heads 111, 112 when capped, so that recovering treatment for sucking the ink which does not contribute to image recording from the discharge ports of the recording heads by negative pressure is effected. Further, the recovery base 12 is provided with a wiper holder base 5, and a wiper 3 is held by a wiper holder 4 provided on the wiper holder base 5. The wiper 3 can clean the discharge port forming surfaces of two recording heads 111, 112. While the wiper holder base 5 is being slid in synchronous with the cap slider 8, it is lifted by a guiding action between a guide groove 5a of the base and a pin 12c of the recovery base 12. In the illustrated embodiment, the wiper 3 is formed from rubber sheet. According to the illustrated embodiment, in the recording heads 111, 112, inks can be discharged from discharge ports (discharge downwardly) formed in the discharge port forming surfaces thereof. A plurality of discharge ports are arranged in a line on each discharge port forming surface along a direction transverse to the main scanning direction (shown by the double-headed arrow A1, A2). By repeating the shifting movement of the recording heads 111, 112 in the main scanning direction (A1, A2) and the conveyance of the recording medium (not shown) in a direction perpendicular to the main scanning direction, an image is formed on the recording medium by ink dots. The recording heads 111, 112 may be designed to have electrical/thermal converters for applying thermal energy to discharge the ink from the discharge ports, for example. A home position HP(6) (Fig. 7) for the recording heads is located at a position rightwardly (toward the direction A2) of and out of a recording area of the recording medium, and predetermined recovering operation is effected in an area between an idle suction position (1) and a wiper turn position (7) including the home position (6). The recording area is located leftwardly (toward the direction A1) of the position (7). In Fig. 7, "DISTANCE (mm)" indicates a shifting distance of the carriage and "NUMBER OF PULSE(S)" indicates the number of pulses of a pulse motor for shifting the carriage. Operating contents in various positions will be described later. Next, a suction pump 11 for generating negative pressure in the caps contacted with the heads when two recording heads 111, 112 are capped by the caps 6a, 6b of the cap slider 8 will be explained. For example, the suction pump 11 is a tube pump disclosed in Japanese Patent Laid-Open No. 8-318624 (1996). In the illustrated embodiment, as shown in Figs. 4 and 5, has sub-roller holders (roller holding means) 14a, 14b for two systems. As the sub-roller holders 14a, 14b are rotated, sub-rollers (rollers) 13a, 13b of the sub-roller holders 14a, 14b are shifted while squeezing suction tubes (elastic tubes) 10a, 10b connected to the caps 6a, 6b to generate negative pressures in the caps 6a, 6b, thereby effecting the suction recovery of the recording heads 111, 112. A construction of the suction pump will be described with reference to Figs. 4 and 5. As shown in Fig. 4, a tube guide surface (guide member) 12a of the recovery base 12 has a semi-circular shape. When the sub-roller holder 14a is rotated in a direction shown by the arrow a, the suction sub-roller 13a is relatively shifted along a cam 14c of the sub-roller holder 14a in a direction shown by the arrow b and is held near an outer periphery of the sub-roller holder 14a by an end (directing toward the direction b) of the cam 14c. In this condition, the suction sub-roller 13a is rotated in the direction a together with the sub-roller holder 14a. In this case, the suction sub-roller 13a squeezes the suction tube 10a disposed between the tube guide surface 12a of the recovery base 12 and the suction sub-roller 13a, thereby generating the negative pressure in the cap 6b to which the suction tube 10a is connected. In order to ensure that the suction sub-roller 13a is positively held near the outer periphery of the cam 14c, i.e., that the suction sub-roller 13a positively squeezes the suction tube 10a, dampers (elastic members) 18a, 18b are provided in a confronting relation to the tube guide surface 12a. The dampers 18a, 18b are mounted to a pump cover 19 which is supported by the recovery base 12. Further, the dampers 18a, 18b are located on a rotation path of the sub-roller 13a. With this arrangement, as the sub-roller holder 14a is rotated in the direction a in Fig. 4, when the suction sub-roller 13a contacts with the damper 18a or 18b, the suction sub-roller 13a is always biased toward the outer periphery of the cam 14c by an elastic force of the damper to urge the tube 10a. When the suction sub-roller 13a is released from the suction tube 10a, the suction sub-roller tries to shift inwardly from the outer periphery of the cam 14c by an elastic force (repelling force) of the suction tube 10a. In this case, the suction sub-roller 13a may abut against an inner peripheral end of the cam 14c to generate collision noise. To avoid this, the damper 18b is provided so that the suction sub-roller 13a is prevented from shifting up to the inner peripheral end of the cam 14c. However, even by adopting such an arrangement, if a position where the suction sub-roller 13a is released from the suction tube 10a is spaced apart from a position of the damper 18b, after the suction sub-roller 13a abuts against the damper 18b, shock may not be absorbed to generate tremble noise between the suction sub-roller and the cam 14c. In the illustrated embodiment, the tube guide surface 12a is extended toward a direction perpendicular to a line connecting between the rotation center of the sub-roller holder 14a and the position where the suction sub-roller 13a is released from the suction tube 10a. With this arrangement, a timing for releasing the suction sub-roller 13a from the suction tube 10a can be delayed, with the result that a distance through which the suction sub-roller 13a strikes against the damper 18b can be shortened, thereby minimizing the collision noise of the suction sub-roller 13a. Further, the other sub-roller holder 14b is rotated in the direction a in Fig. 5, and the suction sub-roller 13b is shifted inwardly along a groove-shaped cam 14d of the sub-roller holder 14b and is rotated together with the sub-roller holder 14b at a position where the suction tube 10b is not sealingly closed. Accordingly, the interior of the cap 6a communicated with the suction tube 10b is communicated with the atmosphere. Conversely, when the sub-roller holder 14b is rotated in the direction b in Fig. 5, the suction sub-roller 13b is relatively shifted along the cam 14b in the direction a and is held near an outer periphery of the sub-roller holder 14b by an end (directing toward the direction a) of the cam 14d. In this condition, the suction sub-roller 13b is rotated in the direction b together with the sub-roller holder 14b. In this case, the suction sub-roller 13b squeezes the suction tube 10b disposed between the tube guide surface 12a of the recovery base 12 and the suction sub-roller 13b, thereby generating the negative pressure in the cap 6a to which the suction tube 10b is connected. In order to ensure that the suction sub-roller 13b is positively held near the outer periphery of the cam 14d, i.e., that the suction sub-roller 13b positively squeezes the suction tube 10b, dampers (elastic members) 18c, 18d are provided in a confronting relation to the tube guide surface 12a. Similar to the dampers 18a, 18b shown in Fig. 4, the dampers 18c, 18d are mounted to the pump cover 19 and are located on a rotation path of the sub-roller 13b. With this arrangement, as the sub-roller holder 14b is rotated in the direction b in Fig. 5, when the suction sub-roller 13b contacts with the damper 18c or 18d, the suction sub-roller 13b is always biased toward the outer periphery of the cam 14d by an elastic force of the damper to urge the tube 10b. When the suction sub-roller 13b is released from the suction tube 10b, the suction sub-roller tries to shift inwardly from the outer periphery of the cam 14d by an elastic force of the suction tube 10b. In this case, the suction sub-roller 13b may abut against an inner peripheral end of the cam 14d to generate collision noise. To avoid this, the damper 18d is provided so that the suction sub-roller 13b is prevented from shifting up to the inner peripheral end of the cam 14d. However, even by adopting such an arrangement, if a position where the suction sub-roller 13b is released from the suction tube 10b is spaced apart from a position of the damper 18d, after the suction sub-roller 13b abuts against the damper 18d, shock may not be absorbed to generate tremble noise between the suction sub-roller and the cam 14d. Similar to the above, in the illustrated embodiment, the tube guide surface 12a is extended toward a direction perpendicular to a line connecting between the rotation center of the sub-roller holder 14b and the position where the suction sub-roller 13b is released from the suction tube 10b. With this arrangement, a timing for releasing the suction sub-roller 13b from the suction tube 10b can be delayed, with the result that a distance through which the suction sub-roller 13b strikes against the damper 18d can be shortened, thereby minimizing the collision noise of the suction sub-roller 13b. The other sub-roller holder 14a is rotated in the direction b in Fig. 4, and the suction sub-roller 13a is shifted along the cam 14c of the sub-roller holder 14a and is held radially inwardly of the sub-roller holder 14a by an end (directing toward the direction a in Fig. 4) of the cam 14c. In this condition, the suction sub-roller is rotated together with the sub-roller holder 14a in the direction b in Fig. 4. In this case, the suction sub-roller 13a is rotated to a position where the suction tube 10a is not sealingly closed, with the result that the suction tube 10a is not squeezed. Thus, the negative pressure is not generated in the suction tube 10a and the interior of the cap 6b communicated with the suction tube 10a is communicated with the atmosphere. Further, when the suction pump 11 is operated in a normal direction (direction b in Figs. 4 to 6), a carriage lock 15 shown in Fig. 6 is lifted via a friction member 15a to lock movement of the carriage 2, and, when the suction pump 11 is operated in a reverse direction (direction a in Figs. 4 to 6), the carriage lock is lowered via the friction member 15a to unlock the movement of the carriage 2. Next, an arrangement around the caps 6a, 6b will be explained. As shown in Fig. 3, the caps 6a, 6b are held by the cap holder 7, and the cap holder 7 is held by the cap slider 8 via a cap spring (not shown). When the carriage 2 is shifted rightwardly (toward the direction A2) beyond the position shown in Fig. 3 (corresponding to the position (3) (CAP) in Fig. 7), the cap holder 7 is lifted to cause the caps 6a, 6b to cap the recording heads 111, 112. Each of the caps 6a, 6b is provided with two holes, and one of two holes in the cap 6a is connected to one end of the suction tube 10b, and the other hole is connected to one end of an atmosphere communicating tube 9b. One of two holes in the cap 6b is connected to one end of the suction tube 10a, and the other hole is connected to one end of an atmosphere communicating tube 9a. The other ends of the atmosphere communicating tube 9a, 9b are inserted into the cap slider 8, and valves 17 are attached to such the other ends via packing members 17a. Each valve 17 is opened and closed by its sliding movement when it is pushed by the cap slider 8, so that it is closed at a position (2) in Fig. 7 and is opened at a position (1). Accordingly, in the position (position (2) in Fig. 7) where the heads are capped and the atmosphere communicating tube 9a, 9b are closed, in accordance with the rotational directions of the sub-roller holders 14a, 14b obtained by the suction pump 11, the recovering operation for sucking the ink from the discharge ports of the recording heads 111, 112 through the suction tubes 10a, 10b is permitted. Further, in the position (position (1) in Fig. 7) where the heads are capped and the atmosphere communicating tube 9a, 9b are opened, in accordance with the rotational direction of the suction pump 11, the idle suction for sucking the residual ink in the caps 6a, 6b and the suction tubes 10a, 10b through the suction tubes 10a, 10b is permitted. The other ends of the suction tubes 10a, 10b act as ink discharge ends 10-la, 10-1b, and the ink discharged from the ink discharge ends 10-1a, 10-1b is sent to a waste ink processing member 210 disposed below the ink discharge ends and are processed there. Figs. 8 and 9 show the caps 6a, 6b in detail, where Fig. 8 is a top view and Fig. 9 is a sectional view taken along the line 9 - 9 in Fig. 8, showing a condition that the discharge ports of the recording heads 111, 112 are sealingly closed by the caps (elastic members) 6a, 6b. As mentioned above, each of the caps 6a, 6b is provided at its bottom with two communication holes which act as an ink suction opening 6c and an atmosphere communicating opening 6d, respectively. In order to prevent scattering of the ink toward the discharge ports of the recording heads 111, 112 and to suck the ink remaining around the discharge ports of the recording heads 111, 112, an ink absorbing members 20 made of porous material are disposed within the caps 6a, 6b. The ink absorbing members 20 are disposed to contact with inner surfaces of the caps 6a, 6b and abut against the ink suction openings 6c and the atmosphere communicating openings 6d. Areas of each ink absorbing member 20 opposed to the ink suction hole and the atmosphere communicating hole of the cap 6a or 5b have thicknesses thinner than the other area. The ink suction openings have substantially the same diameters at areas thereof contacted with the ink absorbing members. The ink suction opening and the atmosphere communicating opening are symmetrically arranged in the vicinity of both longitudinal ends of the cap member. A central area of the ink absorbing member with respect to the longitudinal direction of the cap member has a thickness greater than those of other areas. The longitudinal direction of the cap member substantially coincides with a direction along which the plurality of discharge ports are arranged in a line. In the illustrated embodiment, the thickness of the ink absorbing member is selected to 2.6 mm, and thickness of the areas of the ink absorbing member opposed to the ink suction hole and the atmosphere communicating hole of the cap member is selected to 1.3 mm. With this arrangement, when the ink is absorbed from the recording heads 111, 112, the amount of residual ink in the ink absorbing member 20 is decreased. Even when the apparatus are left as it is for a long term without effecting the recording, occurrence of ink solidification and clogging of the ink absorbing members 20 can be suppressed. If ink solidification or clogging should be partially generated in the ink absorbing members, after the ink starts to flow once, solidified or clogged ink becomes apt to be solved again from the thinner areas of the ink absorbing members. Further, after the ink suction from the recording heads 111, 112, when the interior of the caps 6a, 6b are communicated with the atmosphere, the atmosphere can easily be communicated with the interior of the ink absorbing members 20, thereby effecting the suction of the residual ink (idle suction) positively. In a position (position (5) in Fig. 7) where the caps 6a, 6b are spaced apart from and disposed below the recording heads 111, 112, pre-discharge for discharging the ink not contributing the recording from the recording heads 111, 112 can be performed. Further, in a position (4) a in Fig. 7 ASF (auto sheet feeder) trigger for automatically feeding the recording media can be outputted. Further, the cap slider 8 and the wiper holder base 5 are operated in synchronous with each other, so that, when the carriage 2 is situated rightwardly (toward the direction A2) beyond the position (4) in Fig. 7, the wiper holder base 5 is lifted, by the guide groove 5a and the pin 12c of the recovery base 12, up to a position where the wiper holder base can abut against the recording heads 111, 112, with the result that the wiper lock 16 is engaged by the pawl of the recovery base 12. That is to say, when the carriage 2 is shifted from the left to the right beyond the position (4) in Fig. 7, at his position (4), the wiper 3 is held at a position where the wiper can abut against the head. On the other hand, when the carriage 2 is shifted from the right to the left beyond the position (7) in Fig. 7, at his position (7), the wiper lock 16 is unlocked, with the result that the wiper 3 does not contact with the heads 111, 112. Next, a series wiping operation will be explained. First of all, when the recording apparatus is powered ON, in the locking condition of the carriage lock 15 as shown in Fig. 6, the suction pump 11 is rotated in the normal direction (direction a) by a drive source (not shown), with the result that the locking condition of the carriage 2 attained by the carriage lock 15 is released or unlocked. After the locking condition of the carriage lock 15 is released, the carriage 2 is shifted to the wiper turn position (7) in Fig. 7. The wiping start (trigger) position (4) is located between the cap position (3) and the recording waiting position (PII) 5. While the carriage 2 is being shifted to the recording waiting position (6), the caps 6a, 6b are opened and the wiping operation for the recording heads 111, 112 is effected by the wiper 3. Further, when the carriage 2 is shifted up to the position (7) in Fig. 7, the projection of the carriage 2 abuts against the wiper lock lever 16a to disengage the wiper lock 16 from the pawl of the recovery base 12, with the result that the wiper 3 is shifted downwardly to be retarded from the recording heads 111, 112. In this condition, the wiper 3 does not abut against the recording heads 111, 112. As shown in Fig. 3, the wiper 3 is provided with four slits 3a, 3b, 3c, 3d. The slit 3a is formed at a position corresponding to one of opposed sides of the recording head 112, the slit 3c is formed at a position corresponding to the other of opposed sides of the recording head 112, the slit 3b is formed at a position corresponding to one of opposed sides of the recording head 111, the slit 3c is formed at a position corresponding to the other of opposed sides of the recording head 111. In the illustrated embodiment, the slits 3a, 3b, 3c, 3d are straightly formed in a predetermined area of the sheet-shaped wiper 3 directing from an upper end to a lower end thereof at a position opposed to the opposed sides of the recording head 112 and the opposed sides of the recording head 111. [Second embodiment] Now, a second embodiment of the present invention will be explained with reference to Figs. 10 and 11, regarding features different from those in the first embodiment. Figs. 10 and 11 show a cap of a recovering unit of an ink jet recording apparatus according to the second embodiment of the present invention, where Fig. 10 is a top view of the cap and Fig. 11 is a sectional view taken along the line 11 - 11 in Fig. 10. As shown in Figs. 10 and 11, in the recovering unit of the ink jet recording apparatus according to the second embodiment, only the configuration of the ink absorbing member differs from that in the first embodiment. That is to say, in the first embodiment, while an example that the ink absorbing members 20 abut against the ink suction holes and the atmosphere communicating holes formed in the bottoms of the caps 6a, 6b was explained, in the second embodiment, as shown in Fig. 11, an ink absorbing member 21 abuts against the ink suction hole but does not abut against the atmosphere communicating hole. Further, similar to the first embodiment, a thickness of areas of the ink absorbing member 21 opposed to the ink suction hole and the atmosphere communicating hole of the cap 6a or 6b is thinner than a thickness of the other area. With the arrangement as mentioned above, after the sucking of ink, when the ink remaining in the caps is sucked (idle suction) by communicating the interior of the caps with the atmosphere, since an area of each ink absorbing member 21 directly contacted with the atmosphere is increased, more effective ink absorption can be achieved. Now, a general construction of the above-mentioned ink jet recording head will be described with reference to Fig. 12. A top plate 1100 forming a part of the ink jet recording head H is formed from resin material and integrally includes a top plate member having a liquid chamber 1104 for reserving recording liquid and a plurality of liquid passages 1103, a discharge port forming member 1101 having a plurality of discharge ports (orifices) 1102 communicated with the plurality of liquid passages 1103, respectively, and a recording liquid supplying port member 1105. Further, in a heater board (element substrate) 1107, a plurality of heaters (electrical/thermal converters) 1106 disposed on a silicone substrate and electrical wirings (not shown) made of aluminum or the like for supplying electricity to the heaters are formed by a well-known film forming technique, and the heater board is positioned and secured onto a base plate 1110 by a well-known die-bonding technique. A wiring substrate 1108 is provided with wirings connected to the wirings of the heaters board 1107 by a well-known wire-bonding technique, and a plurality of pads 1109 disposed at ends of the wirings and adapted to receive electrical signals from a main body of the image forming apparatus. The top plate 1100 and the heater board 1107 are joined together in such a manner that the liquid passages 1103 are opposed to the heaters 1106 to form an assembly, and the assembly is secured to the base plate 1110 together with the wiring substrate 1108, thereby forming the ink jet recording head H.

Claims: An ink jet recording apparatus comprising: a cap member capable of sealing a discharge port for discharging ink and being provided at its bottom with an ink suction opening and an atmosphere communicating opening; an ink absorbing member disposed within said cap member; a suction pump communicated with said ink suction opening; and an atmosphere communicating valve communicated with said atmosphere communicating opening; characterised in areas of said ink absorbing member opposed to said ink suction opening and said atmosphere communicating opening are thinner than the other area and said ink absorbing member abuts against said ink suction opening. An ink jet recording apparatus according to claim 1, wherein said ink absorbing member abuts against said atmosphere communicating opening. An ink jet recording apparatus according to claim 1, wherein said ink absorbing member does not abut against said atmosphere communicating opening. An ink jet recording apparatus according to claim 1, wherein said ink suction opening has substantially the same diameter in the vicinity of an area where said ink suction opening abuts against said ink absorbing member. An ink jet recording apparatus according to claim 1, wherein said ink suction opening and said atmosphere communicating opening are disposed symmetrically in the vicinity of both longitudinal ends of said cap member. An ink jet recording apparatus according to claim 1, wherein a central area of said ink absorbing member in a longitudinal direction of said cap member has a thickness greater than those of other areas. An ink jet recording apparatus according to claim 5 or 6, wherein the longitudinal direction of said cap member substantially coincides with a direction along which a plurality of discharge ports are arranged. An ink jet recording apparatus according to claim 1, further comprising an electrical/thermal converter for generating thermal energy used for discharging the ink from said discharge port. A cap for an ink jet recording apparatus, comprising: a cap member capable of sealing a discharge port for discharging ink and being provided at its bottom with an ink suction opening for communication with a suction pump and an atmosphere communicating opening for communication with an atmosphere communicating valve; and an ink absorbing member disposed within said cap member; characterised in areas of said ink absorbing member opposed to said ink suction opening and said atmosphere communicating opening are thinner than the other area and said ink absorbing member abuts against said ink suction opening. A cap according to claim 9, wherein said ink absorbing member abuts against said atmosphere communicating opening. A cap according to claim 9, wherein said ink absorbing member does not abut against said atmosphere communicating opening. A cap according to claim 9, wherein said ink suction opening has substantially the same diameter in the vicinity of an area where said ink suction opening abuts against said ink absorbing member. A cap according to claim 9, wherein said ink suction opening and said atmosphere communicating opening are disposed symmetrically in the vicinity of both longitudinal ends of said cap member. A cap according to claim 9, wherein a central area of said ink absorbing member in a longitudinal direction of said cap member has a thickness greater that those of other areas.

Inventors: KAWARAMA MAKOTO, SUGIMOTO HITOSHI, KAWARAMA, MAKOTO, SUGIMOTO, HITOSHI
Applicants: CANON KK, CANON KABUSHIKI KAISHA
Application year: 1999
Main classification: B41J2
IPC codes: B41J2