Patent Publication Number: US-6712447-B2

Title: Ink jet recording apparatus

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The Present invention relates to an ink jet recording apparatus for effecting recording by using recording means for discharging plural different color inks. 
     2. Related Background Art 
     A recording apparatus having a function such as a printer function, a copier function, a facsimile function and the like, a composite electronic equipment or work station including a computer, a word processor and the like, and a recording apparatus used as an output device of an industrial recording apparatus compositely combined with various types of processing equipments are designed so that an image (including a character and/or a symbol) is recorded (or printed) on a recording medium (recording material) such as a paper, cloth, a plastic sheet, an OHP sheet or the like on the basis of recording information. Such recording apparatuses can be grouped into an ink jet type, a wire dot type, a thermal type, a laser beam type and the like in dependence upon a recording system. 
     In a recording apparatus of serial type in which the recording is effected while performing main scanning along a direction transverse to a conveying direction (paper feeding direction or sub-scanning direction) of a recording medium, an image is recorded by a recording head (as recording means) mounted on a carriage shifted (main-scanned) along the recording medium. In the apparatus, by repeating such an operation that a predetermined amount of sheet feeding (pitch conveyance as sub-scanning) is effected after one-line recording is finished, and then a next line image is recorded (main scanning) on the recording medium which is now stopped, the recording is performed with respect to the entire recording medium. On the other hand, in a recording apparatus of line type in which the recording is effected only by the sub-scanning in the conveying direction of the recording medium (recording material), the recording medium is set at a predetermined recording position, and, by repeating such an operation that a predetermined amount of sheet feeding (pitch feeding) is effected after one-line recording is performed collectively and then next one-line recording is performed collectively, the recording is performed with respect to the entire recording medium. 
     Among such recording apparatuses, a recording apparatus of ink jet type (ink jet recording apparatus) performs the recording by discharging ink from a recording head as recording means toward a recording medium. The ink jet recording apparatus has the following advantages. That is to say, the recording means can easily be made compact, a highly fine image can be recorded at a high speed, an image can be recorded on a plain paper without special treatment, and a running cost is low. Further, since the apparatus is of non-impact type, noise is small, and a color image can easily be recorded by using plural color inks. Further, according to an ink jet recording apparatus of line type using a recording head of line type in which a large number of discharge ports are disposed along a width-wise direction of the recording paper, the recording can be effected at a higher speed. 
     Particularly, in recording means (recording head) of ink jet type for discharging ink by utilizing thermal energy, since high density arrangement of liquid paths (discharge port arrangement or nozzle arrangement) can be realized by means of electrical/thermal converters, electrodes and liquid path walls and a top plate formed on a substrate by a semiconductor manufacturing process such as etching, deposition and/or spattering, further compactness can be achieved. Further, in the ink jet recording apparatus, there have been various requests for the material quality of the recording medium (recording material), and, in recent years, development for such request has been progressed, and, thus, cloth, leather, non-woven fabric, metal and the like has been used as the recording medium, as well as normal recording media such as paper (including a thin paper and a processed or converted paper) and a plastic thin board (OHP and others). 
     In the ink jet recording apparatus, the image is recorded on the recording medium by discharging the ink from a discharge port in response to an electrical signal. In some cases, due to penetration of air into the discharge port or increase in viscosity of the ink by drying, the ink droplet may not be discharged from the discharge port in response to the electrical signal. As one of methods for restoring a normal discharging condition from such ink non-discharging condition (including a poor discharging condition), there is a method (suction recovery means) in which ink not contributing to the image recording is sucked and discharged from the discharge port. In such suction recovery means, in many cases, as one of means (pressure generating devices) for generating ink sucking negative pressure, a tube pump in which a negative pressure is generated in a pump tube by rotating a pump roller while urging the pump roller against the pump tube, i.e., by squeezing the pump tube, has been used. As suction recovery means, for example, there is an arrangement in which a suction hole is formed in a cap capable of capping the recording head and the tube pump is connected to the suction hole. 
     In some cases, the cap and the tube pump are designed to be driven cooperatively in accordance with a rotational direction of a driving source (for example, a purge motor) of a recovery unit. That is to say, first of all, the cap is urged against an ink discharge port forming face (discharge port face) of the recording head by a normal rotation of the purge motor, thereby capping the recording head. Then, the tube pump is driven reversely by a reverse rotation of the purge motor. When driven reversely, in the tube pump, the pump roller is rotated while being urged against the pump tube to squeeze the pump tube, thereby generating the negative pressure. The negative pressure is introduced into the cap through the suction hole. In this case, since the recording head is capped by the cap, the viscosity increased ink and/or bubbles unsuitable for the recording are sucked from the discharge ports of the recording head by the negative pressure introduced into the cap, and the different color inks flow toward the single suction hole of the cap through a cap absorbing body provided upwardly, thereby discharging the inks forcibly. Thereafter, by rotating the purge motor in the normal direction, the cap is separated from the ink discharge port forming face of the recording head to thereby release the capping. In this way, the suction recovery operation is completed. 
     However, in the recovery unit used in the conventional ink discharge recovery device including the above-mentioned arrangement, there is the following technical problem to be solved. That is to say, due to recent colorization, high image quality and high resolution, since the number of ink discharge ports has been increased, the number of ink colors has been increased and a size of the discharged ink droplet has been decreased, the handling of the recording head becomes more delicate. Thus, there is caused such trouble that different color inks enter into different color discharge ports to cause mixing of color (color mixing) in recording, with the result that a correct color recorded image cannot be obtained. This trouble frequently occurs in the suction recording operation. To cope with this, although a technique in which respective color discharge ports (or nozzles) are sucked by respective suction caps or a technique in which respective color discharge ports are successively sucked by a single cap, can be considered, such techniques make the mechanism more complicated and more bulky, and increase the cost and increase the suction recovery time. Further, in the technique in which the suction is effected by using the single cap, there is an apparatus having the technique in which, from after the suction recovery to immediately before the recording (printing), by discharging and discarding the ink in the vicinity of the discharge ports of the recording head, the inks in the respective color discharge ports (respective color nozzles) are made pure and then the recording is started. Also in this apparatus, as the number of discharge ports (nozzles) is increased, an amount of ink to be discarded tends to increase, and, thus, there still remains a technical problem (to be solved) that consumption of ink is hastened. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide an ink jet recording apparatus which can prevent different ink from entering into different discharge port even when plural different inks are sucked by using a single cap and which can recover a normal image recording condition of recording means having no color mixing with a simple and cheap construction and with a short time pre-ejection operation having low consumption of ink, and can prevent ink contamination within the apparatus by reducing generation of ink mist caused by the pre-ejection. 
     Another object of the present invention is to provide an ink jet recording apparatus for effecting recording by using recording means for discharging plural different inks, which comprises a cap for covering a plurality of discharge ports for discharging the different inks and a pump connected to a suction hole of the cap and adapted to generate negative pressure within the cap, and in which the discharge ports and the suction hole are arranged so that an ink flow path from the discharge ports to the suction hole when the inks are sucked from the discharge ports by operating the pump are not passed through the different ink discharge ports. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic perspective view showing an appearance of an embodiment of an ink jet recording apparatus to which the present invention is applied; 
     FIG. 2 is a schematic perspective view showing an internal structure of the ink jet recording apparatus according to the embodiment, with an outer frame member, recording means and ink tanks removed; 
     FIG. 3 is a schematic longitudinal sectional view showing main parts of the ink jet recording apparatus of FIG. 2; 
     FIG. 4 is a schematic perspective view showing an entire construction of a recording head ink cartridge in which ink tanks are mounted to recording heads as recording means used in the ink jet recording apparatus according to the embodiment; 
     FIG. 5 is a schematic perspective view showing the recording heads and the ink tanks decomposed from the recording head cartridge of FIG. 4; 
     FIG. 6 is a schematic exploded perspective view showing constructural parts of the recording head as the recording means of FIG. 5; 
     FIG. 7 is a schematic perspective view showing a carriage used in the ink jet recording apparatus according to the embodiment, looked at from a front side; 
     FIG. 8 is a schematic perspective view of the carriage of FIG. 7, looked at from a rear side; 
     FIG. 9 is a schematic perspective view showing an entire construction of a recovery unit mounted to the ink jet recording apparatus according to the embodiment; 
     FIG. 10 is a schematic perspective view showing the entire construction of the recovery unit, looked at from another side; 
     FIG. 11 is a block diagram showing an entire construction of an electrical circuit of the ink jet recording apparatus according to the embodiment; 
     FIG. 12 is a flow chart showing a recording operation sequence of the ink jet recording apparatus according to the embodiment; 
     FIG. 13 is a schematic perspective view showing a structure of a cap unit according to a first embodiment used in the recovery unit of the ink jet recording apparatus to which the present invention; 
     FIG. 14 is an exploded perspective view of the cap unit, looked at from the above; 
     FIG. 15 is an exploded perspective view of the cap unit, looked at from the below; 
     FIG. 16 is a schematic explanatory view showing a positional relationship between discharge port arrays and suction holes of the cap when the recording head is capped by the cap unit of FIG. 13; 
     FIG. 17 is a schematic perspective view of a cap unit according to a second embodiment used in the recovery unit of the ink jet recording apparatus to which the present invention is applied; 
     FIG. 18 is an exploded perspective view of the cap unit of FIG. 17, looked at from the above; 
     FIG. 19 is an exploded perspective view of the cap unit of FIG. 17, looked at from the below; 
     FIGS. 20A,  20 B,  20 C and  20 D are views showing examples of a positional relationship between discharge port arrays and suction holes of the cap in a cap unit according to a third embodiment used in the recovery unit of the ink jet recording apparatus to which the present invention is applied; 
     FIGS. 21A,  21 B and  21 C are views showing examples of a positional relationship between discharge port arrays and suction holes of the cap in a cap unit according to a fourth embodiment used in the recovery unit of the ink jet recording apparatus to which the present invention is applied; 
     FIG. 22 is a view showing an alteration of the positional relationship between discharge port arrays and suction holes of the cap in the fourth embodiment shown in FIGS. 21A to  21 C; 
     FIG. 23 is a flow chart showing an operation sequence of recovery processing of the ink jet recording apparatus according to the embodiment; and 
     FIG. 24 is a partial perspective view schematically showing a structure of an ink discharge portion of the recording means of FIG.  4 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention will now be fully explained in connection with embodiments thereof with reference to the accompanying drawings. Incidentally, in the drawings, the same or corresponding elements are designated by the same reference numerals. Further, in the specification, a term “recording” (also referred to as “print(ing)”) means that not only meaningful information such as a character and/or a figure is formed, but also an image, figure, pattern or the like (which may be or may not be visualized to be visually recognized by human being) is formed on a print medium or the medium is processed or converted, regardless of meaningful and meaningless. Here, the “print medium” includes not only a paper used in general printing apparatus but also any members capable of receiving ink, such as cloth, plastics, film, metallic plate, glass, ceramics, wood material, leather and the like. Further, a term “ink” (also referred to as “liquid”) should be construed widely similar to the definition of the above-mentioned “print(ing)” and means any liquid applied to formation of the image, figure, pattern by being attached to the print medium or the like or applied to processing or conversion of the print medium or treatment of ink (for example, solidification or insolubility of coloring material ink applied to the print medium). 
     In embodiments which will be described later, a printer will be described as an example of a recording apparatus using an ink jet recording system. Now, a fundamental construction of the printer will be explained with reference to FIGS. 1 to  12 . FIG. 1 is a schematic perspective view showing an appearance of an embodiment of an ink jet recording apparatus to which the present invention is applied, FIG. 2 is a schematic perspective view showing an internal structure of the ink jet recording apparatus according to the embodiment, with an outer frame member, recording means and ink tanks removed, and FIG. 3 is a schematic longitudinal sectional view showing main parts of the ink jet recording apparatus of FIG.  2 . 
     First of all, a main body of the ink jet recording apparatus will be explained with reference to FIGS. 1 to  3 . In FIG. 1, a main body M 1000  of the ink jet recording apparatus to which the present invention is applied is constituted by an outer frame members such as a lower case M 1001 , an upper case M 1002 , an access cover M 1003  and a paper discharge tray M 1004 , and a chassis M 3019  (refer to FIG. 2) housed within the outer frame member. The chassis M 3019  is constituted by a plurality of plate-shaped metallic members having predetermined rigidity and constitutes a frame-work of the recording apparatus and serves to support (or hold) the above-mentioned various recording mechanisms and recovery operation mechanism. Further, the lower case M 1001  forms a substantially lower half of the main body M 1000 , and the upper case M 1002  forms a substantially upper half of the main body M 1000 , and, by combining these cases M 1001  and M 1002 , a hollow structure for containing various mechanisms which will be described later therein is defined, and openings are formed in an upper surface and a front surface of the hollow structure, respectively. 
     Further, the paper discharge tray M 1004  has one end rotatably held onto the lower case M 1001  so that the opening formed in the front surface of the lower case can be opened and closed by rotation of the tray. Thus, when the recording operation is carried out, the paper discharge tray M 1004  is rotated forwardly to open the opening, so that a recording sheet as a recording medium can be discharged through the opening and the recording sheets P can be stacked onto the tray successively. Further, two auxiliary trays M 1004   a,  M 1004   b  are contained in the paper discharge tray M 1004  so that a supporting area for the paper (recording medium, recording sheet) can be increased or decreased with three stages by extending or retracting these auxiliary trays. 
     The access cover M 1003  has one end rotatably held onto the upper case M 1002  so that an access opening formed in an upper surface of the upper case can be opened and closed. With this arrangement, by opening the access cover M 1003 , a recording head cartridge H 1000  as recording means or ink tanks H 1900  contained within the main body can be exchanged. Incidentally, when the access cover M 1003  is opened or closed, a projection (not shown) formed on a back surface of the cover rotates a cover opening/closing lever (not shown) so that, by detecting a rotated position of the lever by a microswitch or the like, an open condition or a closed condition of the access cover can be detected. 
     Further, on an upper rear surface of the upper case M 1002 , there are provided a power source key E 0018  and a resume key E 0019  which can be depressed and there is also provided an LED E 0020 , so that, when the power source key E 0018  is depressed, the LED E 0020  is turned ON to inform the operator of the fact that the recording operation can be performed. Further, the LED E 0020  has various displaying functions, for example, for changing a flashing manner or changing color or actuating a buzzer E 0021  (FIG. 11) to inform the operator of trouble of the printer. Incidentally, when the trouble is eliminated, the recording operation is re-started by depressing the resume key E 0019 . 
     Next, a recording operation mechanism according to the illustrated embodiment, contained and held in the main body M 1000  of the recording apparatus will be explained. The recording operation mechanism according to the illustrated embodiment comprises an automatic feeding portion M 3022  for automatically feeding the recording sheet P into the main body, a conveying portion M 3029  (FIG. 3) for directing the recording sheet P successively fed out from the automatic feeding portion to a desired recording position and for directing the recording sheet P from the recording position to a discharging portion M 3030  (FIG.  3 ), a recording portion M 4000  for effecting desired recording on the recording sheet P conveyed by the conveying portion, and a recovery portion (recovery unit) M 5000  (FIGS. 9 and 10) for effecting recovery process with respect to the recording portion M 4000  and the like. 
     First of all, the automatic feeding portion M 3022  will be fully described with reference to FIGS. 2 and 3. The automatic feeding portion M 3022  according to the illustrated embodiment is designed so that recording sheets P stacked in a condition inclined with respect to a horizontal plane by an angle of about 30 to 60 degrees, may be fed out in a horizontal posture, and fed into the main body M 1000  through a feed opening (not shown) while maintaining the recording sheet in the horizontal posture. That is to say, the automatic feeding portion M 3022  is provided with a feed roller portion M 3026 , side guides M  3024 , a pressure plate M 3025 , an ASF (auto sheet feeder) base M 3023 , separation sheets M 3027 , and a separation pawl (not shown). Among them, the ASF base M 3023  substantially constitutes an outer frame of the automatic feeding portion M 3022  and is provided at a back surface side of the main body M 1000 . Further, at a front surface side of the ASF, the pressure plate M 3025  for supporting the recording sheet P is attached to be inclined with respect to the horizontal plane by an angle of about 30 to 60 degrees, and a pair of sheet guides (side guides) M 3024   a,  M 3024   b  are protruded from the pressure plate. One (M 3024   b ) of the sheet guides can be slid in a horizontal direction so that a distance between the sheet guides can be adjusted to accommodate a horizontal side (width) of the recording sheet. 
     Further, at left and right sides of the ASF base M 3023 , a drive shaft M 3026   a  driven in synchronous with a purge motor E 0003  via a transmission gear (not shown) is rotatably supported, and a plurality of feed rollers M 3026  having an irregular circumference shape are secured to the drive shaft M 3026   a.  By rotating the feed roller portion M 3026  by driving the purge motor E 0003  (FIGS.  10  and  11 ), the recording sheets P stacked on the pressure plate M 3025  are separated and fed out one by one from an uppermost recording sheet on the sheet stack by a separation action of the separation sheets M 3027  and the separation pawl, and the separated recording sheet is conveyed to the conveying portion (sheet feeding portion) M 3029 . Incidentally, since a lower end of the pressure plate M 3025  is elastically supported by pressure plate springs M 3028  disposed between the plate and the ASF base M 3023 , an abutting force between the feed roller portion M  3026  and the recording sheet P can be kept constant regardless of the number of stacked recording sheets P. 
     Further, in a conveying path extending from the automatic feeding portion M 3022  to the conveying portion M 3029 , an PE (paper end) lever M 3020  biased in a clockwise direction (FIG. 3) by an PE (paper end) lever spring M 3021  is rotatably supported onto a chassis M 3019  comprised of a plate-shaped metallic member having predetermined rigidity and secured to the main body M 1000 . When the recording sheet P separated and fed from the automatic feeding portion M 3022  passes through the conveying path and one end of the recording sheet urges one end of the lever M 3020  to rotate the latter, an PE sensor (not shown) detects rotation of the PE lever M 3020 , so that the fact that the recording sheet P enters into the conveying path is detected. After the penetration of the recording sheet P into the conveying path is detected, the recording sheet P is conveyed by means of the feed roller portion M 3026  toward a downstream direction by a predetermined distance. In the conveying operation of the feed roller portion M 3026 , after the end of the recording sheet P abuts against a nip between a line feed roller (conveying roller) M 3001  (now stopped) and a pinch roller portion M 3014  which are provided in the conveying portion M 3029  (described later), the recording sheet P is stopped to have a loop of about 3 mm. 
     Next, the conveying portion M 3029  will be fully described with reference to FIGS. 2 and 3. The conveying portion M 3029  according to the illustrated embodiment includes the LF (line feed) roller (conveying roller) M 3001 , the pinch roller portion M 3014  and a platen M 2001 . The LF roller M 3001  is secured to a drive shaft rotatably supported onto the chassis M 3019 , and an LF intermediate gear M 3012  is driven in synchronous with a drive gear provided on a drive shaft of an LF motor E 0002  (described later) and is rotated by a driving force of the LF motor E 0002 . Incidentally, an LF gear cover M 3002  is mounted on one end of the drive shaft to which the LF roller M 3001  is secured. The LF gear cover M 3002  serves to protect an LF gear train for driving the LF roller M 3001 . That is to say, the LF gear train is in synchronous with the drive gear provided on the drive shaft of the LF motor (conveying motor) E 0002  and is rotated by the driving force of the LF motor E 0002 . 
     Further, the pinch roller portion M 3014  is rotatably supported onto a tip end portion of a pinch roller holder M 3015  rotatably supported by the chassis M 3019  and is urged against the LF roller M 3001  by a pinch roller coil spring M 3016  for biasing the pinch roller holder M 3015 , and is rotatingly driven by the rotation of the LF roller M 3001  so that it cooperates with the LF roller M 3001  to pinch the recording sheet P which is now stopped in the looped condition therebetween and to convey the recording sheet forwardly. In the conveying portion M 3029  constructed in this way, when a predetermined time period is elapsed after the conveying operation of the feed roller portion M 3026  of the automatic feeding portion M 3022  is stopped, the driving of the LF motor E 0002  is started, and the driving force of the LF motor E 0002  is transmitted to the LF roller M 3001  via the LF intermediate gear M 3012  and LF gear M 3003 , with the result that the recording sheet the leading end of which abuts against the nip between the LF roller M 3001  and the pinch roller portion M 3014  is conveyed to a record starting position on the platen M 2001  by the rotation of the LF roller M 3001 . In this case, since the feed roller portion M 3026  starts to rotate again simultaneously with the LF roller M 3001 , the recording sheet P is conveyed in the downstream conveying direction for a predetermined time period by the cooperation between the feed roller portion M 3026  and the LF roller M 3001 . 
     FIG. 4 is a schematic perspective view showing an entire construction of a recording head cartridge which ink tanks are mounted to a recording head as recording means used in the ink jet recording apparatus according to the illustrated embodiment. FIG. 5 is a schematic perspective view of the recording head cartridge of FIG. 4 which is decomposed into the recording head and the ink tanks. FIG. 6 is a schematic exploded perspective view showing constructural elements of the recording head as the recording means of FIG.  5 . The recording head cartridge H 1000  as the recording means is detachably mounted to a carriage M 4001 . That is to say, the recording head cartridge H 1000  is shifted together with the carriage M 4001  reciprocally shifted in a direction (scanning direction) transverse to the conveying direction of the recording sheet P along a carriage shaft M 4012  having both ends secured to the chassis M 3019  and serves to record an ink image on the recording sheet P waited at the recording start position by discharging ink on the basis of predetermined image information. 
     After the ink image is recorded, predetermined amount conveyance (for example, conveyance of the recording sheet P at a line unit of 5.42 mm conveyance) is effected by the rotation of the LF roller M 3001 , and, after such conveyance is finished, the carriage M 4001  effects the scanning along the carriage shaft M 4012 . By repeating such recording and conveyance, the recording of the ink image is carried out with respect to the recording sheet P positioned on the platen M 2001 . Further, regarding the carriage shaft M 4012 , one end thereof is mounted to a sheet-to-sheet adjusting plate (not shown) via a sheet-to-sheet adjusting lever M 2015  and the other end is mounted to the other sheet-to-sheet adjusting plate M 2012  via a carriage shaft cam M 2011  in a biased condition provided by a carriage shaft spring M 2014 . The sheet-to-sheet adjusting plate M 2012  and the sheet-to-sheet adjusting plate (not shown) are adjusted to provide a proper distance between a discharge port face of the recording head cartridge H 1000  and a record supporting surface M 2001   a  of the platen M 2001  and then are secured to the chassis M 3019 . 
     Further, the sheet-to-sheet adjusting lever M 2015  can selectively be set at two stop positions, i.e., an upper end position shown in FIG. 1 and a lower end position (not shown), by the action of a sheet-to-sheet lever spring (not shown). When the sheet-to-sheet adjusting lever M 2015  is shifted to the lower end position, the carriage M 4001  is shifted in a direction away from the platen M 2001  by about 0.6 mm. When the recording sheet P is a thick sheet such as an envelope, the sheet-to-sheet adjusting lever M 2015  is previously shifted to the lower end position and then the feeding operation of the automatic feeding portion M 3022  is started. Further, when the sheet-to-sheet adjusting lever M 2015  has already been shifted to the lower end position, since a sheet-to-sheet sensor (gap sensor) E 0008  (refer to FIG. 11) detects such a condition, when the feeding operation of the automatic feeding portion M 3022  for the recording sheet P is started, it is judged whether the position setting of the sheet-to-sheet adjusting lever M 2015  is proper or not. If an improper condition is detected, alarm is issued by displaying a message or operating a buzzer, thereby preventing the recording operation from being performed in the improper condition. 
     Next, the paper discharge portion M 3030  will be fully described with reference to FIGS. 2 and 3. As shown in FIG. 3, the paper discharge portion M 3030  according to the illustrated embodiment includes a paper discharge roller M 2003 , a paper discharge gear M 3013  mounted to the paper discharge roller M 2003  and adapted to transmit the driving force of the LF motor E 0002  to the paper discharge roller M 2003  via the LF intermediate gear M 3012 , a first spur roller M 2004  urged against the paper discharge roller M 2003  by a biasing force of a spur spring shaft M 2009  attached to a first spur holder M 2007  mounted to a spur stay M 2006  and rotatingly driven by rotation of the paper discharge roller M 2003  and adapted to convey the recording sheet P while pinching the recording sheet between the first spur roller and the paper discharge roller M 2003 , and a paper discharge tray M 1004  on which the discharge recording sheets P are stacked. 
     Although the recording sheet conveyed to the paper discharge portion M 3030  is subjected to a conveying force of the paper discharge roller M 2003  and the first spur roller M 2004 , since the rotational center of the first spur roller M 2004  is offset from the rotational center of the paper discharge roller M 2003  by about 2 mm upstream in the conveying direction, the recording sheet P conveyed by the paper discharge roller M 2003  and the first spur roller M 2004  is lightly contacted with the recording sheet supporting surface M 2001   a  of the platen M 2001  without any gap therebetween, thereby conveying the recording sheet properly and smoothly. 
     Further, in order to prevent the slack of the recording sheet P, the conveying force of the paper discharge roller M 2003  and the first spur roller M 2004  is set to be slightly greater than a conveying force of the LF roller M 3001  and the pinch roller portion M 3014 . Further, the spur stay M 2006  holds a second spur roller M 2005  disposed at a downstream side of the first spur roller M 2004  and mounted to a second spur holder M 2008 , thereby preventing the recording sheet P from being slidingly contacted with the spur stay M 2006 . After the ink image is recorded on the recording sheet P, when the trailing end of the recording sheet P leaves the nip between the LF roller M 3001  and the Pinch roller portion M 3014 , the recording sheet P is conveyed only by the paper discharge roller M 2003  and the first spur roller M 2004 , and the discharging of the recording sheet P is completed. 
     Next, the recording portion M 4000  will be fully described. The recording portion M 4000  comprises the carriage M 4001  shiftably guided and supported by the carriage shaft M 4012 , and the recording head cartridge H 1000  as the recording means detachably mounted to the carriage M 4001 . First of all, the recording head cartridge H 1000  will be explained with reference to FIGS. 4 to  6 . As shown in FIG. 4, the recording head cartridge H 1000  according to the illustrated embodiment has ink tanks H 1900  for storing inks and a recording head H 1001  for discharging the ink supplied from the ink tank H 1900  in response to recording information, and the recording head H 1001  is of so-called cartridge type detachably mounted to the carriage M 4001  which will be described later. 
     In the recording head cartridge H 1000  disclosed here, in order to permit high quality color recording like photograph, as the ink tanks, for example, there are prepared color ink tanks for independent colors such as black, light cyan, light magenta, cyan, magenta and yellow, and, as shown in FIG. 7, the respective ink tanks are detachable with respect to the recording head H 1001 . As shown in the exploded perspective view of FIG. 6, the recording head H 1001  is constituted by a recording element substrate H 1100 , a first plate H 1200 , an electrical wiring substrate H 1300 , a second plate H 1400 , a tank holder H 1500 , a flow path forming member H 1600 , filters H 1700  and rubber seals H 1800 . A plurality of recording elements for discharging the ink and Al (aluminum) electrical wirings for supplying electric power to the recording elements are formed on one surface of an Si substrate (silicon substrate) of the recording element substrate H 1100  by a film forming technique. A plurality of ink flow paths and a plurality of discharge ports H 1100 T (discharge ports  1182 ) which corresponds to the recording elements are formed by a photo-lithography technique, and ink supply ports for supplying the inks to the plural ink flow paths are formed to be opened to the back surface of the substrate. 
     Further, the recording element substrate H 1000  is securely welded to the first plate H 1200 , and ink supply ports H 1201  for supplying the inks to the recording element substrate H 1100  are formed in the first plate H 1200 . Further, the second plate H 1400  having an opening is securely welded to the first plate H 1200 , and the second plate H 1400  holds the electrical wiring substrate H 1300  so that the electrical wiring substrate H 1300  is electrically connected to the recording element substrate H 1100 . The electrical wiring substrate H 1300  serves to apply to the recording element substrate H 1100  an electrical signal for causing the discharging of the ink and has electrical wirings corresponding to the recording element substrate H 1100 , and external signal input terminals (contact portions) H 1301 , disposed at ends of the electrical wirings, for receiving electrical signals from the main body. The external signal input terminals H 1301  are positioned and secured to the back surface of the tank holder H 1500 . 
     On the other hand, the flow path forming member H 1600  is welded to the tank holder H 1500  for detachably holding the ink tanks H 1900 , by ultrasonic welding, so that ink paths H 1501  extending from the ink tanks H 1900  to the first plate H 1200  is formed. Further, the filters H 1700  are provided at ink tank side ends of the ink flow paths H 1501  engaged by the ink tanks H 1900 , thereby preventing external dirt and contaminants from entering into the flow paths. Further, the rubber seals H 1800  are provided at the engagement portions with the ink tanks H 1900 , thereby preventing the ink from being evaporated through the engagement portions. Further, by joining the tank holder portion comprised of the tank holder H 1500 , the flow path forming member H 1600 , the filters H 1700  and the rubber seals H 1800  as mentioned above to the recording element portion (ink discharge portion) comprised of the recording element substrate H 1100 , the first plate H 1200 , the electrical wiring substrate H 1300  and the second plate H 1400  by welding, the recording head H 1001  is formed. 
     FIG. 7 is a schematic perspective view showing a front side of the carriage mounted to the ink jet recording apparatus according to an embodiment of the present invention, and FIG. 8 is a schematic perspective view showing a back side of the carriage of FIG.  7 . Next, the carriage M 4001  will be described with reference to FIGS. 2,  7  and  8 . As shown in these drawings, the carriage M 4001  is provided with a carriage cover M 4002  engaged by the carriage and adapted to guide the recording head H 1001  to a mounting position on the carriage, and a head set lever M 4007  engaged by the tank holder H 1500  of the recording head H 1001  and adapted to urge the recording head to set the recording head at a predetermined mounting position. 
     That is to say, the head set lever M 4007  is rotatably provided on a head set lever shaft M 4008  at an upper part of the carriage M 4001 , and a head set plate (not shown) is mounted to an engagement portion with the recording head H 1001  via a spring. With this arrangement, the recording head H 1001  is mounted to the carriage M 4001  while being urged by a spring force of the spring. Further, another engagement portion (of the carriage) with the recording head H 1001  of the carriage M 4001  is provided with a contact flexible print cable (referred to as “contact FPC” hereinafter) E 0011 , and, by electrically contacting contact portions E 0011   b  on the contact FPC E 0011  with the contact portions (external signal input terminals) H 1301  of the recording head H 1001 , the receiving of various informations for the recording and the supplying of the electric power to the recording head H 1001  can be effected. 
     Here, an elastic member (not shown) such as rubber is provided between the contact portions E 0011   a  of the contact flexible print cable (contact FPC) E 0011  and the carriage M 4001 , so that the contact portions E 0011   a  are positively contacted with the carriage M 4001  by an elastic force of the elastic member and an urging force of the head set lever spring. Further, the contact FPC E 0011  is extended beyond both sides of the carriage M 4001 , and, as shown in FIGS. 7 and 8, both end portions of the cable are pinched and secured to the both sides of the carriage M 4001  by a pair of FPC pressing members M 4003 , M 4006  and are connected to a carriage substrate E 0013  (refer to FIG. 8) mounted to the back surface of the carriage. 
     Further, as shown in FIG. 8, the carriage substrate E 0013  is electrically connected to a main substrate E 0014  provided on the chassis M 3019  via a carriage flexible flat cable (CRFFC) E 0012 . Further, the other end of the carriage flexible flat cable E 0012  is secured to the chassis M 3019  (FIG. 2) by an FFC pressing member M 4028 , and is extended toward the back surface side through a hole (not shown) formed in the chassis to be connected to the main substrate E 0014  (FIG.  11 ). As shown in FIGS. 8 and 11, the carriage substrate E 0013  is provided with an encoder sensor E 0004 . By detecting information on an encoder scale E 0005  provided, in parallel with the carriage shaft M 4012 , between both side surfaces of the chassis M 3019 , the position and scanning speed of the carriage M 4001  can be detected. 
     In the illustrated embodiment, the encoder sensor E 0004  is an optical sensor of permeable type, and the encoder scale E 0005  is formed by alternately and at a predetermined pitch printing light shielding portions for shielding detection light from the encoder sensor E 0004  and light permeable portions for permitting the passage of the detection light on a film made of resin such as polyester by a technique such as photographic process. Accordingly, the position of the carriage M 4001  shifted along the carriage shaft M 4012  can be detected at any time by using, as a reference, a position of the carriage at the time when the carriage abuts against one of side plates of the chassis M 3019  provided at ends on the scanning track of the carriage M 4001 , and counting the number of patterns formed on the encoder scale E 0005  by the encoder sensor E 0004  as the carriage M 4001  scans. 
     Further, the carriage M 4001  performs the scanning while being guided by the carriage shaft M 4012  and a carriage rail M 4013  provided between both sides of the chassis M 3019 , and a pair of carriage bearings M 4029  obtained by impregnating lubricant such as oil into sintered metal are integrally formed with a bearing portions of the carriage shaft M 4012  by insert-molding or the like. Further, at an abutting portion between the carriage M 4001  and the carriage rail M 4013 , there is provided a carriage slider (CR slider) M 4014  as an abutting member made of resin having excellent sliding ability and anti-wear property, which slider cooperates with the carriage bearings (CR bearings) M 4029  to permit smooth scanning of the carriage M 4001 . 
     Further, the carriage M 4001  is connected to a carriage belt (timing belt) M 4018  provided in substantially parallel with the carriage shaft M 4012  between an idler pulley M 4020  (FIG. 2) and a carriage motor pulley M 4024  (FIG.  2 ), so that, by shifting the carriage belt M 4018  in a forward or rearward direction by driving the carriage motor pulley M 4024  by means of the carriage motor E 0001  (FIGS.  2  and  11 ), the carriage M 4001  can be scanned along the carriage shaft M 4012 . Further, the carriage motor pulley M 4024  is held at a fixed position by the chassis M 3019 ; whereas, the idler pulley M 4020  is shiftably held together with a pulley holder M 4021  with respect to the chassis M 3019  and is biased toward a direction away from the motor pulley M 4024  by a spring force. Thus, proper or moderate tension is always applied to the carriage belt M 4018  mounted between the pulleys M 4020  and M 4024 , thereby maintaining a good mounting condition having no slack. 
     Incidentally, a carriage belt stop M 4019  is provided at an attachment portion between the carriage M 4001  and the carriage belt M 4018 , so that the carriage M 4001  can positively be connected (attached) to the carriage belt M 4018 . Further, in the scanning track or path of the carriage M 4001  on the spur stay M 2006 , there is provided an ink end sensor E 0006  (FIG. 11) exposed and opposed with respect to the ink tanks in order to detect the remaining amount of inks stored in the ink tanks H 1900  of the recording head cartridge H 1000  mounted to the carriage. 
     The recording head H 1001  as the recording means according to the illustrated embodiment is ink jet recording means adapted to discharge the ink by utilizing thermal energy and having electrical/thermal converters for generating the thermal energy. Further, the head H 1001  serves to effect the recording (printing) by discharging the ink from the discharge port by utilizing change in pressure due to growth and contraction of a bubble generated by film boiling caused in the ink by the thermal energy applied by the electrical/thermal converter. 
     FIG. 24 is a partial perspective view schematically showing a structure of the ink discharge portion including a discharge port array of the recording head H 1001 . In FIG. 24, in a discharge port face  1181  (corresponding to the recording element substrate H 1100 ) opposed to the recording medium P such as the recording paper with a predetermined gap (for example, about 0.2 mm to about 2.0 mm) therebetween, a plurality of discharge ports  1182  (corresponding to the discharge ports H 1100 T) are formed with a predetermined pitch, and electrical/thermal converters (such as heat generating resistance bodies)  1185  for generating ink discharging energy are disposed along wall surfaces of liquid paths  1184  communicating a common liquid chamber  1183  with the discharge ports  1182 . The recording head H 1001  is mounted to the carriage M 4001  in such a manner that the discharge ports  1182  are positioned side by side in a direction transverse to the main scanning direction (shifting direction of the carriage M 4001 ). As such, there is provided the recording head (recording means) H 1001  of ink jet type in which the electrical/thermal converter  1185  is driven in response to an image signal or a discharge signal to cause the film boiling in the ink within the liquid path  1184  and the ink is discharged from the discharge port  1182  by the pressure generated by the film boiling. 
     FIG. 9 is a schematic perspective view showing an entire construction of the recovery unit mounted to the ink jet recording apparatus according to the embodiment of the present invention, and FIG. 10 is a schematic perspective view showing the entire construction of the recovery unit of FIG. 9, looked at from a different direction. Next, the recovery unit M 5000  constituting the recovery portion for effecting recovery process for recovering and maintaining ink discharging performance of the recording head cartridge H 1000  will be explained with reference to FIGS. 9 and 10. The recovery portion (recovery unit) M 5000  according to the illustrated embodiment is designed to be detachable with respect to the main body M 1000  independently. The recovery unit M 5000  is constituted by recovery process means comprising a cleaning mechanism for removing foreign matters adhered to the recording element substrate (discharge port forming face) of the recording head H 1001 , and a discharging mechanism for effecting suction discharge or pressurized discharge (pre-ejection) for discharging the ink in order to normalize (refresh the ink) the ink flow paths extending from the ink tanks H 1900  to the recording element substrate H 1100  of the recording head H 1001  (flow paths extending from the ink flow paths H 1501  to the second plate H 1400  through the flow path forming member H 1600 ). 
     In FIGS. 9 and 10, the purge motor E 0003  serves as a recovery driving source for driving a cap M 5001 , a pump M 5100  and wiper blades M 5011 , M 5012   a,  M 5012   b  which will be described later. Incidentally, in the illustrated embodiment, the purge motor E 0003  also serves as a driving source for driving the automatic feeding portion M 3022 . In the purge motor E 0003 , a driving force is picked up from both sides of a motor shaft, and the driving force at one side drives the pump M 5100  or the automatic feeding portion M 3022  via drive switching means (described later) and the driving force at the other side drives the cap M 5001  and the wiper blades M 5011 , M 5012   a,  M 5012   b  via a one-way clutch M 5041 . In this case, only when the purge motor E 0003  is rotated in a specific rotational direction (referred to as “normal direction” hereinafter; whereas, an opposite direction is referred to as “reverse direction”), the one-way clutch M 5041  is engaged to drive the cap M 5001  and the wiper blades M 5011 , M 5012   a,  M 5012   b.  Accordingly, when the purge motor E 0003  is being rotated in the reverse direction, since the one-way clutch M 5041  is rotated idly not to transmit the driving force, the cap M 5001  and the wiper blades M 5011 , M 5012   a,  M 5012   b  are not driven. 
     The cap M 5001  is formed from rubber material and is attached to a cap lever M 5004  rotatable around an axis. The cap M 5001  is shifted in directions shown by the arrow A (FIG. 9) via the one-way clutch M 5041 , a cap drive transmission gear train M 5110 , a cap cam and the cap lever M 5004  so that the cap can abut against the recording element substrate H 1100  of the recording head H 1001  to cover the plural discharge ports H 1100 T (discharge ports  1182 ) or the cap can be separated from the recording element substrate. The cap M 5001  is provided with a cap absorbing member M 5002 , and the cap absorbing member M 5002  is disposed to be opposed to the recording element substrate H 1100  with a predetermined gap therebetween in a capping condition. 
     By providing the cap absorbing member M 5002 , during the suction operation, the ink discharged from the discharge ports H 1100 T (discharge ports  1182 ) of the recording head cartridge H 1000  can be received. A cap tube M 5009  is connected to the cap M 5001 , and the cap tube M 5009  is connected to a pump tube M 5019  of the pump M 5100  (described later) to discharge the ink from a cap suction port M 5001   a  (refer to FIGS. 14 to  16 ). 
     Further, the wiper blades M 5011 , M 5012   a,  M 5012   b  are formed from flexible members made of rubber and are attached to a blade holder M 5013  in such a manner that end edge portions of the blades are protruded upwardly. Further, a lead screw M 5031  is inserted through the blade holder M 5013 , and a projection (not shown) of the blade holder M 5013  is shiftably engaged by a helical groove M 5031   a  formed in the lead screw. Thus, as the lead screw M 5031  is rotated to rotate the blade holder M 5013 , the blade holder M 5013  is reciprocally shifted in directions shown by the arrows B 1  and B 2  (FIG.  9 ), with the result that the wiper blades M 5011 , M 5012   a,  M 5012   b  wipe and clean (wiping) the recording element substrate H 1100  (discharge port face  1181 ) of the recording head cartridge H 1000 . The lead screw M 5031  is connected to the purge motor E 0003  via the one-way clutch M 5041  and a wiper driving transmitting gear train M 5120 . 
     The pump M 5100  is a suction pump for generating pressure (negative pressure) by squeezing the pump tube M 5019  by means of a pump roller M 5018 . The pump M 5100  is connected to the other side of the purge motor E 0003  via drive switching means for switching a driving force transmitting path between the automatic feeding portion M 3022  and the pump M 5100  and a pump drive transmitting gear train M 5130 . Further, although not described in detail, the pump M 5100  is provided with a mechanism capable of releasing an urging force of the pump roller M 5018  (against the pump tube) for squeezing the pump tube M 5019 , so that, when the purge motor E 0003  is rotated in the normal direction, the urging force of the pump roller M 5018  is released not to squeeze the pump tube M 5019 , and, when the purge motor E 0003  is rotated, in the reverse direction, the urging force of the pump roller M 5018  squeezes the pump tube M 5019 . Further, one end of the pump tube M 5019  is connected to the cap M 5001  via the cap tube M 5009 . 
     The driving switching means comprises a pendulum arm M 5026  and a switching lever M 5043 . The pendulum arm M 5026  is designed to rotate in a direction shown by the arrow C 1  (FIG. 10) or a direction shown by the arrow C 2  around a shaft M 5026   a  in accordance with the rotational direction of the purge motor E 0003 . Further, the switching lever M 5043  is switched in accordance with the position of the carriage M 4001 . That is to say, when the carriage M 4001  is shifted above the recovery unit M 5000 , a part of the switching lever M 5043  abuts against a part of the carriage M 4001  to shift the switching lever M 5043  in a direction shown by the arrow D 1  (FIG. 10) or in a direction shown by the arrow D 2  in accordance with the position of the carriage M 4001 , with the result that a lock pin M 5043   a  of the switching lever M 5043  can be fitted into a lock hole M 5026   b  of the pendulum arm M 5026 . Incidentally, a purge sensor E 0010  serves to detect the position of the cap M 5001 . 
     Next, an operation of the recovery unit M 5000  having the above-mentioned construction will be explained. First of all, an operation of the automatic feeding portion M 3022  effected also by using the purge motor as the driving source of the recovery unit M 5000  will be described. In a condition that the carriage M 4001  is in a retard (or retired) position where the carriage does not abut against the switching lever M 5043 , when the purge motor E 0003  is rotated in the reverse direction, the pendulum arm M 5026  is rocked in the direction C 1  (FIG. 10) via a pendulum drive transmitting gear train M 5150 , with the result that a switching output gear M 5027  attached to the pendulum arm M 5026  is engaged with an ASF gear M 5064  provided at one end of ASF drive transmitting gear train M 5160 . In this condition, when the purge motor E 0003  continues to rotate in the reverse direction, the automatic feeding portion M 3022  is driven via the ASF drive transmitting gear train M 5160 . In this case, since the driving force is not transmitted to the cap M 5001  and the wiper blades M 5011 , M 5012   a,  M 5012   b  due to the idle rotation of the one-way clutch M 5041 , the wiper blades are not driven. 
     Next, a suction recovery operation which is one of recovery processes of the recovery unit M 5000  having the above-mentioned construction will be explained. The suction recovery operation is performed by using the pump M 5100 . First of all, in the condition that the carriage M 4001  is in the retard position where the carriage does not abut against the switching lever M 5043 , when the purge motor E 0003  is rotated in the normal direction, the pendulum arm M 5026  is rocked in the direction C 2  via the pendulum drive transmitting gear train M 5150 , with the result that the switching output gear M 5027  attached to the pendulum arm M 5026  is engaged with the pump gear M 5053  provided at one end of the pump drive transmitting gear train M 5130 . Thereafter, when the carriage M 4001  is shifted to a capping position (carriage position where the recording element substrate (discharge port face) H 1100  of the recording head cartridge H 1000  is opposed to the cap M 5001 ), a part of the carriage M 4001  abuts against a part of the switching lever M 5043  to rotate the switching lever M 5043  in the direction D 1 . As a result, since the lock pin M 5043   a  of the switching lever M 5043  is fitted into the lock hole M 5026   b  of the pendulum arm M 5026 , the pendulum arm M 5026  is locked in a condition that it is connected to the pump. 
     Here, when the purge motor E 0003  is rotated in the reverse direction to squeeze the pump tube M 5019  by the urging force of the pump roller M 5018 , the negative pressure is applied to the recording element substrate H 1100  (discharge port face  1181 ) of the recording head cartridge H 1000 , with the result that ink not suitable for the recording (ink including solidified ink and the like) and bubbles are forcibly sucked from the discharge ports  1102  of the recording element substrate. Thereafter, when the purge motor E 0003  is rotated in the inverse direction, the pressure in the cap tube M 5009  and the cap M 5001  is returned to the atmospheric pressure, and the forcible suction operation from the ink discharge ports  1182  of the recording element substrate H 1100  of the recording head cartridge H 1000  is stopped, thereby finishing the suction operation. 
     Next, a wiping operation of the recovery unit M 5000  having the above-mentioned construction will be explained. In the wiping operation, the purge motor E 0003  is firstly rotated in the normal direction. Due to the normal rotation of the purge motor E 0003 , the wiper blades M 5011 , M 5012   a,  M 5012   b  are shifted to a wiping start position (position where the wiper blades M 5011 , M 5012   a,  M 5012   b  are positioned at an upstream side of the recording head cartridge (in the recording operation) in a condition that the cap M 5001  is spaced apart from the recording head cartridge H 1000  (recording head H 1001 )). 
     Then, the carriage M 4001  is shifted to the wiping position. The wiping position is a position where the wiper blades M 5011 , M 5012   a,  M 5012   b  are opposed to the recording element substrate H 1100  forming the discharge port face (discharge port forming face)  1181 . In this case, the carriage M 4001  does not abut against the switching lever M 5043 , and the pendulum arm M 5026  is not locked. Here, the purge motor E 0003  is rotated in the normal direction, with the result that the wiper blades M 5011 , M 5012   a,  M 5012   b  wipe and clean (cleaning) the recording element substrate H 1100  of the recording head cartridge H 1000  while shifting in the direction B 1  (FIG.  9 ). Further, contaminants adhered to the wiper blades M 5011 , M 5012   a,  M 5012   b  are removed (cleaned) by wiper blade cleaning means (not shown) provided at a downstream side of the recording element substrate H 1100  of the recording head cartridge H 1000  in the recording operation direction. In this case, the cap M 5001  is maintained (held) in the spaced apart condition. 
     When the wiper blades M 5011 , M 5012   a,  M 5012   b  reach a wiping finish position (downstream end position in the recording operation direction), the purge motor E 0003  is stopped, and the carriage M 4001  is shifted to a wiping retard position (out of a range through which the wiper blades M 5011 , M 5012   a,  M 5012   b  are shifted). Thereafter, the purge motor E 0003  is rotated in the normal direction to shift the wiper blades M 5011 , M 5012   a,  M 5012   b  to the wiping finish position. Incidentally, also in this case, the cap M 5001  is maintained in the spaced apart condition. In this way, the wiping operation of the recovery unit M 5000  is finished. 
     Next, pre-ejection which is one of the recovery processes of the ink jet recording apparatus according to the illustrated embodiment will be explained. If the suction operation and/or the wiping operation are effected with respect to the recording head for effecting the recording by discharging plural color inks, there may arise a problem regarding mixing of inks. For example, when the suction operation is finished, there may arise a phenomenon that the inks sucked from the ink discharge ports by the suction flow reversely with respect to the recording head H 1001  being under the negative pressure due to the suction, and, in this case, other color ink may enter into different color discharge port  1182  or various color inks adhered around the discharge ports during the wiping operation may be pushed into different color discharge ports by the wipers. Due to such factors, when the next recording is started, initial ink may be color-changed (color-mixed), thereby deteriorating the image. 
     An operation for in advance ejecting (discharging) the color-mixed ink immediately before the recording in order to prevent the color mixing is referred to as pre-ejection. In the illustrated embodiment, as shown in FIG. 10, a pre-ejection port (pre-ejection receiver) M 5045  for receiving the ink discharged by the pre-ejection is disposed in the vicinity of the cap M 5001 , and, after the recording element substrate H 1100  of the recording head H 1001  is shifted to be opposed to the pre-ejection port M 5045  immediately before the recording, the pre-ejection is carried out. Incidentally, the pre-ejection port M 5045  is defined by a pre-ejection absorbing body M 5046  and a pre-ejection cover M 5047 , and the pre-ejection absorbing body M 5046  is connected to an ink containing portion (waste ink absorbing portion)(not shown). 
     FIG. 11 is a block diagram showing an entire construction of an electrical circuit of the ink jet recording apparatus according to an embodiment of the present invention. Next, the construction of the electrical circuit of the ink jet recording apparatus according to the illustrated embodiment will be explained with reference to FIG.  11 . The electrical circuit of the ink jet recording apparatus according to the illustrated embodiment is mainly constituted by a carriage substrate (CRPCB; CR printed circuit board) E 0013 , a main substrate (main PCB) E 0014 , a power source unit E 0015 , etc. Here, the power source unit E 0015  is connected to the main substrate (main PCB) E 0014  and serves to supply various driving sources. Further, the carriage substrate E 0013  is a print substrate unit mounted to the carriage M 4001  (FIG. 8) and acts as an interface for sending/receiving a signal with respect to the recording head H 1001  via a contact FPC E 0011 . Further, this substrate serves to detect change in positional relationship between the encoder scale E 0005  and the encoder sensor E 0004  on the basis of a pulse signal outputted from the encoder sensor E 0004  as the carriage M 4001  is shifted, and to output an output signal (detection signal) to the main substrate E 0014  through the carriage flexible flat cable (CRFFC) E 0012 . 
     Further, the main substrate (main PCB) E 0014  is a print substrate unit for controlling the driving of various parts of the ink jet recording apparatus according to the illustrated embodiment, and, on this substrate, there are provided I/O ports corresponding to a sheet end detection sensor (PE sensor) E 0007 , an auto sheet feed sensor (ASF sensor) E 0009 , a cover sensor E 0022 , a parallel interface (parallel I/F) E 0016 , a serial interface (serial I/F) E 0017 , a resume key E 0019 , an LED (light emitting element) E 0020 , a power source key E 0018  and a buzzer E 0021 . Further, the main substrate (main PCB) E 0014  is connected to the carriage motor E 0001 , LF motor E 0002  and purge motor E 0003  to control the driving of such motors, and has connection interfaces for connection to the sheet-to-sheet sensor (GAP sensor) E 0008 , purge sensor E 0010 , carriage flexible flat cable (CRFFC) E 0012  and power source unit E 0015 . 
     FIG. 12 is a flow chart showing the operation of the ink jet recording apparatus according to the embodiment of the present invention. Next, the operation of the ink jet recording apparatus as constructed above will be explained with reference to FIG.  12 . In FIG. 12, when the ink jet recording apparatus is connected to an AC power source, first of all, a first initialization process of the apparatus is executed in a step S 1 . In this initialization process, an electric circuit system such as a ROM and a RAM of the apparatus is checked to ascertain that the apparatus can correctly be operated electrically. Then, in a step S 2 , it is judged whether the power source key E 0018  provided on the upper case M 1002  of the main body M 1000  is turned ON or not. If the power source key E 0018  is turned ON, the program goes to a next step S 3 , where a second initialization process is executed. In this second initialization process, various driving mechanisms and head system of the apparatus are checked. That is to say, it is ascertained whether the apparatus is operated correctly when the various motors are initialized and the head information is read in. 
     Then, in a step S 4 , waiting for event is effected. That is to say, command event from an external I/F, panel key event effected by user&#39;s manipulation, internal control event, etc. are monitored with respect to the apparatus, and, when such event is generated, a process corresponding to such event is executed. For example, in the step S 4 , if recording (print) command event is received from the external I/F, the program goes to a step S 5 . In the step S 5 , if power source key event effected by the user&#39;s manipulation is generated, the program goes to a step S 10 . In the step S 10 , if other event is generated, the program goes to a step S 11 . Here, in the step S 5 , a record command from the external I/F is analyzed to judge designated paper type, paper size, recording quality and paper feed method, data representing a judged result is stored in a RAM E 2005  of the apparatus, and then, the program goes to a step S 6 . Then, in the step S 6 , the paper feeding is started by the paper feeding method designated in the step S 5  to send the paper to the recording start position, and then, the program goes to a step S 7 . 
     In the step S 7 , the recording operation is performed. In the recording operation, recording data sent from the external I/F is temporarily stored in a print buffer, and then, the carriage motor E 0001  is driven to start the shifting of the carriage M 4001  in the scanning direction and to supply the recording data stored in the print buffer to the recording head H 1001 , thereby effecting one-line recording. When the one-line recording of the recording data is finished, the LF motor E 0002  is driven to rotate the LF roller M 3001 , thereby conveying the paper as the recording medium in the sub-scanning direction. Thereafter, the above operations are executed repeatedly. When one page recording of the recording data is finished, the program goes to a step S 8 . In the step S 8 , the LF motor E 0002  is driven to drive the paper discharge roller M 2003 , thereby effecting the paper feeding until it is judged that the paper is fed out from the apparatus completely. When the paper feeding is finished, the paper is discharged onto the paper discharge tray M 1004   a  completely. 
     Then, in a step S 9 , it is judged whether the recording operation for all pages to be recorded is finished or not. If there is any page(s) to be recorded, the program is returned to the step S 5 , from which the operations in the steps S 5  to S 9  are repeated. At a time when the recording operation for all pages to be recorded is finished, the recording operation is completed, and, thereafter, the program is returned to the step S 4 , where next event is waited. On the other hand, in a step S 10 , a process for ending a printer is executed to stop the present apparatus. That is to say, after the power source is shifted to a turn-off allowable condition to disenable the power of the motors, the head, etc., the power source is turned OFF and the program is returned to the step S 4  to wait for next event. Further, in the step S 11 , a process for other event than the above is executed. For example, a process corresponding to a recovery process command of the recording head from the various panel keys or the external I/F or internally generated recovery event is executed. Incidentally, after the process is finished, the program is returned to the step S 4 , where next event is waited. 
     FIG. 23 is a flow chart showing operation sequence of the recovery process effected by the recovery unit M 5000  of the ink jet recording apparatus to which the present invention is applied. Here, while the ink discharging according to the illustrated embodiment will be explained, the ink discharging is effected in accordance with the recovery process of the recording head H 1001 . The recovery process of the recording head H 1001  is executed, for example, under a circumstance generated when the recording head H 1001  is mounted to the recording apparatus, when the ink tank H 1900  is mounted or exchanged, when a predetermined time period is elapsed after the recording head H 1001  and the ink tanks H 1900  are mounted, when predetermined amount recording is carried out or when the operator judges that trouble such as deterioration of image quality of the recorded result occurs. 
     In FIG. 23, in a step S 100 , if the CPU E 1001  judges that there is such a circumstance, the program goes to a next step S 101 , where a mode of the recovery process to be executed in accordance with that circumstance is analyzed. In the illustrated embodiment, the recovery process generically includes suction process, wiping process and pre-ejection process. The suction process is a process operation in which the ink is sucked and discharged from the discharge ports of the recording head by generating the negative pressure within the cap by driving the pump M 5100  of the recovery unit M 5000  in a condition that the discharge ports H 1100 T (or  1182 ) of the recording head H 1001  is closely sealed by the cap M 5001 . Further, the wiping process is a process operation in which the wiper blades M 5011 , M 5012   a, M 5012   b  of the recovery unit M 5000  are driven to wipe and clean the surface of the discharge port face  1181  (or recording element substrate H 1100 ) of the recording head H 1001 . Further, the pre-ejection process is a process operation in which the inks in the discharge ports are refreshed by discharging the inks from the discharge ports of the recording head H 1001 , thereby restoring and maintaining the ink discharging performance of the recording head in the condition suitable for the recording. 
     In FIG. 23, in the step S 101 , if the type of the desired recovery process operation is suction process, the program goes to a step S 102 . The suction process is executed, for example, when the recording head H 1001  is mounted to the recording apparatus or when the ink tank H 1900  is mounted or exchanged or when the operator judges that the trouble of the recorded result occurs. In the step S 102 , when the suction process is commanded, first of all, the carriage M 4001  is driven and scanned up to the position where the cap M 5001  of the recovery unit M 5000  is opposed to the recording head H 1001 . Thereafter, the cap M 5001  of the recovery unit M 5000  is urged against the discharge port face  1181  (recording element substrate M 1100 ) of the recording head H 1001  to create the capping condition, and then the pump M 5100  is driven (step S 105 ). 
     By this operation, the ink is sucked from the recording head H 1001  via the cap M 5001 , and the sucked ink is directed from the suction port of the cap to the pump tube M 5019  and is discharged into the waste ink absorbing body (not shown) as the ink containing portion provided in the lower case M 1001 . When the suction operation is finished, the program goes to a step S 106 , where the wiping process is executed. The wiping process is a process operation in which the ink adhered to the discharge port face  1181  (recording element substrate M 1100 ) during the suction process is cleaned and removed by driving the wiper blades M 5011 , M 5012   a,  M 5012   b.  After the wiping process, the program goes to a step S 107 , where the pre-ejection process is executed. The pre-ejection process is a process operation in which the carriage M 4001  is driven and scanned up to a position where the discharge port face  1181  of the recording head H 1001  is opposed to a pre-ejection port M 5045  provided in the recovery unit M 5000 , and, in this condition, the inks in the discharge ports  1182  are refreshed by preliminarily discharging the inks by driving the recording head H 1001 . The ink discharged by the pre-ejection process is directed to and collected in an ink containing portion (for example, waste ink absorbing body M 5200  shown in FIG. 9) arranged at a predetermined position through the pre-ejection port M 5045 . 
     Further, in the step S 101 , if the desired recovery process is the wiping process, the program goes to a step S 108 , where only the wiping process is executed; whereas, if the desired recovery process is the pre-ejection process, the program goes to a step S 111 . In the illustrated embodiment, a condition that only the wiping process is desired or requested is, for example, a case where the ink greater than a predetermined amount is discharged during the recording. Further, a condition that only the pre-ejection is desired or requested is, for example, a case where a time period during which the ink is not discharged is elapsed for a predetermined time or more. Incidentally, the driving of the recovery unit M 5000  (step S 109 ) and the pre-ejection process (step S 110 ) effected during the wiping process in the step S 108 , and, the driving of the carriage M 4001  (step S 112 ) and ink discharging caused by driving the recording head (step S 113 ) effected during the pre-ejection process in the step S 111  are carried out substantially in the same manner as the aforementioned corresponding operations. 
     Next, various embodiments of a cap unit of a recovery unit M 5000  having most characteristic constructions in the ink jet recording apparatus to which the present invention is applied and in the suction method fo the apparatus will be explained. FIGS. 13 to  16  show main parts of the recovery portion in a first embodiment of the ink jet recording head to which the present invention is applied, and the recovery portion (recovery unit) M 5000  according to the illustrated embodiment is designed to include a cap M 5001 . FIG. 13 is a perspective view showing a condition that the cap M 5001 , cap absorbing body M 5002  and flow path forming member M 5005  are incorporated into a cap holder M 5003 . FIG. 14 is an exploded perspective view of FIG. 13, and FIG. 15 is an exploded perspective view showing an exploded condition of FIG. 14, looked at from another direction. FIG. 16 is a view showing a relative positional relationship between the discharge ports H 1100 T (discharge ports  1182 —see FIG. 24) and suction ports M 5005   a  of the flow path forming member M 5005  of the cap M 5001  when the cap M 5001  abuts against the recording element substrate H 1100  (discharge port face  1181 ), and ink flows until the inks flown from the discharge ports H 1100 T reach the suction ports M 5005   a  during the suction recovery process operation. 
     As shown in FIG. 14, during the suction recovery operation of the recovery unit (recovery portion) M 5000  of the present invention, when the negative pressure condition is established within the cap M 5001  due to the negative pressure generated by the pump M 5100 , the ink is flown from the discharge ports H 1100 T of the recording element substrate H 1100  of the recording head H 1001  and then is discharged from the suction port M 5001   a  of the cap through the plurality (three in the illustrated example) of suction ports M 5005   a  provided in the flow path forming member M 5005  constituting a part of the cap through the cap absorbing body M 5002 . As shown in FIG. 16, each of the three suction ports M 5005   a  provided in the flow path forming member M 5005  of the cap M 5001  is disposed at a center between a pair of discharge port arrays among a plurality of discharge port arrays each including plural discharge ports H 1100 T, and the inks flown out from the discharge ports H 1100 T of each discharge port array reach the corresponding suction port M 5005   a  through paths shown by the arrows. 
     By such an action, the amount of ink flown out from other discharge port array and passing by each discharge port is decreased. Consequently, amounts of different color inks stayed in the vicinity of each discharge port H 1100 T immediately after the suction operation are decreased, with the result that a rate of different color ink flowing into the discharge port H 1100 T due to the ink back flow generated when the negative pressure in the recording head H 1001  (caused by the suction operation) is released, is decreased. Thus, while the amount of inks discharged from the discharge ports H 1001 T in the pre-ejection operation executed after the subsequent wiping operation is reduced, the problem regarding the color mixing (in which different color inks are mixed) due to the back flow of the inks into the discharge ports can be eliminated. 
     FIGS. 17 to  19  show main parts of a recovery portion according to a second embodiment of an ink jet recording apparatus to which the present invention is applied, and the recovery portion (recovery unit) M 5000  according to this embodiment also includes a cap M 5001 . FIG. 17 is a perspective view showing a condition that the cap M 5001 , cap absorbing body M 5002  and flow path forming member M 5005  are incorporated into the cap holder M 5003 , FIG. 18 is an exploded perspective view of FIG. 17, and FIG. 19 is an exploded perspective view showing the exploded condition of FIG. 18, looked at from a different direction. As shown in FIGS. 17 to  19 , by providing a plurality (three in the illustrated example) of suction ports M 5001   a  in the cap M 5001 , the same effects as the first embodiment can be achieved. Further, the discharged inks may be joined in a path extending from the cap holder M 5003  to the pump M 5100  or the cap suction ports may be connected to respective pumps M 5100 . 
     FIGS. 20A to  20 D are views showing several examples of a positional relationships between the discharge port arrays of the recording head and the cap suction ports in a third embodiment of a cap unit used in the recovery unit of the ink jet recording apparatus to which the present invention is applied. As shown in FIGS. 20A to  20 D, even when relative positional relationships between the plural cap suction ports M 5001   a  and the plural discharge port arrays are selected as shown in FIGS. 20A to  20 D, respectively, the same or more effects as the first and second embodiments can be achieved. FIG. 20A shows an arrangement in which each suction port is positioned at ends of the discharge port arrays so that ink flows from the discharge ports to the cap suction ports M 5001   a  are prevented from being crossed. This is one example of the positional relationship between the discharge port arrays of the recording head and the cap suction ports when the arrangement of the cap suction ports M 5001   a  is restricted or limited by the construction of the apparatus. If the arrangement is limited in this way, the arrangement may be selected in accordance with the limitation. FIGS. 20B,  20 C and  20 D show examples of the positional relationship between the discharge port arrays and the cap suction ports, in which the number of cap suction ports M 5001   a  is increased (greater in order of FIG. 20B to FIG. 20D) as comparison with the first and second embodiment of the present invention, so that the concentration of inks flown from the discharge port arrays is avoided and paths between the discharge ports and the cap suction port M 5001   a  are shortened, thereby enhancing efficiency. FIG. 20B shows an arrangement in which the number of cap suction ports M 5001   a  is increased by one as comparison with the positional relationship between the discharge port arrays of the recording head and the cap suction ports in the first embodiment. Although this arrangement becomes more complicated, respective ink flows are more spaced apart from each other, thereby achieving more excellent effect. FIG. 20C shows an arrangement in which the cap suction ports M 5001   a  are disposed between adjacent discharge port arrays regarding all of the discharge port arrays. This is more effective in the point that the inks from the discharge port arrays are not mixed. FIG. 20D shows an arrangement in which the cap suction port M 5001   a  is disposed at a middle position of each discharge port array. This is more effective in the point that the inks from the discharge port arrays are not mixed. 
     FIGS. 21A to  21 C are views showing several examples of a positional relationships between the discharge port arrays of the recording head and the cap suction ports in a fourth embodiment of a cap unit used in the recovery unit of the ink jet recording apparatus to which the present invention is applied, and FIG. 22 is a view showing an alteration of the positional relationship between the discharge port arrays and the cap suction port in the fourth embodiments shown in FIGS. 21A to  21 C. 
     Here, not only when the discharge port arrays are in parallel, but also even when the discharge port arrays are in serial, by arranging them as shown in FIGS. 21A,  21 B and  21 C, the same effects as the aforementioned embodiments can be achieved. 
     Further, as shown in FIG. 22, by arranging a single cap suction port M 5001   a  at a center of six (in total) discharge port arrays comprised of two rows (two discharge port arrays in serial) and three columns three discharge port arrays side by side), six discharge port arrays can be associated with the single suction port. 
     Incidentally, in the above-mentioned embodiments, the same ink is discharged from the plural discharge ports constituting one discharge port array, and the plural inks are discharged by providing a plurality of discharge port arrays. However, as the case may be, one type ink may be discharged by using one discharge port and plural different inks may be discharged from plural discharge ports. The present invention can similarly be applied to an ink jet recording apparatus having such recording means, thereby achieving the same effects. Such an ink jet recording apparatus is also included within the scope of the invention. 
     According to the above-mentioned embodiments, in the ink jet recording apparatus in which the recording is effected by using the recording means (recording head H 1001 ) for discharging the plural different inks, there is provided the suction recovery mechanism comprising the cap M 5001  for covering the plural discharge ports H 1100 T (or  1182 ) for discharging the different inks, and the pump M 5100  connected to the suction port M 5001   a  of the cap (or suction ports M 5005   a  of the flow path forming member M 5005  constituting the part of the cap) to apply negative pressure in the cap, and, as shown in FIG. 16, FIGS. 20A to  20 D, FIGS. 21A to  21 C, and FIG. 22, the discharge port and the suction port(s) are arranged in such a manner that flow paths of the ink flowing from each discharge port to the suction port when the ink is sucked from each discharge port by driving the pump does not pass by the discharge ports for different inks. 
     Further, in the above-mentioned embodiments, the plurality of suction ports M 5001   a  or M 5005   a  are formed, and a flow path of the ink flowing from each discharge port H 1100 T of the recording head H 1001  to at least one suction port is arranged not to pass by the discharge ports for the different inks. Further, in the above-mentioned embodiments, an arrangement in which the discharge ports for different inks are not disposed on the same line connecting between each discharge port and the suction port, or an arrangement in which a plurality of suction ports are formed in the cap and the discharge ports for the different inks are not disposed on the same line connecting between each discharge port, and at least one suction port is adopted. Further, in the above-mentioned embodiments, the plural different inks may be different color inks or inks having the same color but different densities. Furthermore, in the above-mentioned embodiments, the recording head H 1001  as the recording means has a plurality of discharge port arrays for discharging plural different inks, and each discharge port array includes a plurality of discharge ports for discharging the same ink. 
     According to the above-mentioned embodiments, since the inks sucked from the discharge ports H 1100 T (or  1182 ) can be sent out of the cap in such a manner that each ink does not pass by the different ink discharge ports, even when the plural different inks are sucked by using the single cap M 5001 , the ink can be prevented from entering into the different ink discharge ports. Thus, the recording means can be recovered to the normal or correct image recording condition without any color mixing with simple and cheap construction and with pre-ejection operation having low consumption of ink for a short time. Further, an ink jet recording apparatus in which generation of ink mist due to the pre-ejection can be reduced to prevent contamination of the interior of the apparatus and a suction recovery method for such an apparatus are provided. 
     Incidentally, in the above-mentioned embodiments, while an example that the ink jet recording apparatus of serial type in which the recording is effected while shifting the recording head as the recording means in the main scanning direction has been explained, the present invention can similarly be applied to an ink jet recording apparatus of line type in which the recording is effected only by the sub-scanning by using an ink jet head of line type having a length to cover a whole width or a part of the width of the recording medium, thereby achieving the same effects. Further, the present invention can similarly be applied regardless of the number of recording heads and regardless of the number of discharge port arrays or discharge ports provided in the single recording head, such as a recording head having a plurality of discharge port arrays or discharge ports in the same discharge port face, and, further, can similarly be applied to a color ink jet recording apparatus in which the recording is effected with plural different colors by using a single recording head or plural recording heads, or a gradation record ink jet recording apparatus in which the recording is effected with the same color but different densities, or an ink jet recording apparatus having a combination thereof, thereby achieving the same effects. 
     Further, the present invention can similarly be applied to any arrangement having any positional relationship between a recording head and an ink tank, such as an arrangement using an exchangeable ink jet cartridge in which a recording head and an ink tank are formed integrally, or an arrangement using recording means in which an ink tank is detachably mounted to a recording head or an arrangement in which a recording head and an ink tank are separately provided and the recording head and the ink tank are interconnected by an ink supply path, thereby achieving the same effects. Further, in the above-mentioned embodiments, while an example that the recording head in which the liquid ink is discharged from the recording head has been explained, the present invention can similarly be applied to an ink jet recording apparatus in which the recording is effected by liquidizing solid ink and discharging the liquidized ink, and such an ink jet recording apparatus is also included in the scope of the invention. 
     Further, for example, while the present invention can be applied to an apparatus utilizing electrical/thermal converters such as piezo-electric elements, among them, in an ink jet recording apparatus using a recording head of type in which ink is discharged by utilizing thermal energy, the present invention provides excellent effects. According to such a type, high density recording and highly fine recording can be achieved.