Abstract:
A wiping unit for wiping a nozzle formation face of a recording head of an ink jet recording apparatus includes a slider reciprocally moving in a direction parallel with the nozzle formation face. A wiper is supported by the slider. One end of the wiper is pressed against the nozzle formation face as a wiping operation when the slider moves in a first direction, while as a rubbing operation when the slider moves in a second direction opposed to the first direction. A supporter rotatably supports the other end of the wiper on the slider. A spring urges the wiper toward the nozzle formation face while keeping an attitude of the wiper directed by a reaction force generated when the wiping operation is executed. A rotation limitter restricts the rotation of the wiper such that the wiper is rigidly supported by the slider when the rubbing operation is executed.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to an ink jet recording apparatus comprising a head maintenance unit for maintaining the jetting characteristic of a recording head. 
     An ink jet recording apparatus comprises: a recording head mounted on a carriage reciprocating in a main scanning direction; and recording medium feeder for feeding a recording medium such as a recording sheet intermittently a predetermined amount in a subscanning direction at one time for jetting ink drops from the recording head to the opposed recording medium for recording while moving the recording head in the main scanning direction. 
     A monochrome ink jet recording apparatus normally is equipped with one recording head. A full-color ink jet recording apparatus is equipped with a black ink recording head for jetting black ink and color recording heads for jetting color inks of yellow, cyan, magenta, etc. Such a configuration is disclosed in Japanese Patent Publication No. 7-132615A, for example. 
     The principle of jetting ink from each recording head of the ink jet recording apparatus is as follows: As well known, ink is pressurized by a predetermined pressure in a pressure generating chamber and based on the pressure, ink is jetted as an ink drop of controlled size to the recording medium from each nozzle orifice in a nozzle formation face. Therefore, the ink jetting characteristic from each nozzle orifice of the recording head needs to be maintained constant and if the ink jetting characteristic varies, degradation of the record quality results. 
     The ink jetting characteristic of the recording head varies because of a rise in viscosity caused by evaporation and drying of ink in the nozzle orifices, ink hardening, clogging, deposition of dust, mixing of air bubbles, etc. Thus, the ink jet recording apparatus is provided with a head maintenance unit for excluding the variation causes of the ink jetting characteristic to maintain the ink jetting characteristic of the recording head constant for maintaining the jetting characteristic of the recording head. 
     First, the head maintenance unit comprises a capping unit. At the non-recording time, the capping unit seals the nozzle formation face for isolating the nozzle orifices from the outside, thereby suppressing drying of ink and arise in ink viscosity. 
     If the capping unit seals the nozzle formation face, clogging the nozzle orifices, mixing air bubbles into an ink flow passage, etc., cannot completely be prevented. Then; second the head maintenance unit comprises a suction pump capable of forcibly sucking and discharging ink from the nozzle orifices to remove clogging of the nozzle orifice and the mixed air bubbles. With the suction pump, negative pressure is made to act on the nozzle orifices in a state in which the capping unit seals the nozzle formation face, and ink is forcibly sucked and discharged from the nozzle orifices for removing the clogging, the mixed air bubbles, etc. Normally, the forcible ink sucking and discharging processing with the suction pump is executed when the record operation is restarted after the recorder halts for a long time or the user, who recognizes degradation of the record image quality, operates a dedicated switch on an operation panel. 
     If the forcible ink sucking and discharging processing with the suction pump is executed as described above, ink may be scattered and deposited on the nozzle formation face of the recording head and a meniscus of ink in each nozzle orifice is disordered. A foreign substance easily adheres to the nozzle orifices of the recording head over time. Then, third the head maintenance unit comprises a wiper for wiping the nozzle formation face as required. 
     The wiper has a plate-like wiping member made of a composite material comprising a wiping material made of an elastic plate of rubber, etc., on one side and a rubbing member having the same shape as the wiping material, made of felt, etc., on an opposite side and a holder for pinching and supporting the base end side of the wiping member. While the margin of the tip side of the wiping member is pressed elastically against the nozzle formation face, the wiping member is relatively reciprocated for cleaning the nozzle formation face. For example, the wiping material is pressed against the nozzle formation face at the forth or back motion time, and the rubbing material is pressed against the nozzle formation face at the back or forth motion time, thereby cleaning the nozzle formation face. 
     The cleaning operation with the wiping material of the wiping member is called “wiping operation.” The “wiping operation” takes an important role of uniforming, namely, stabilizing a meniscus of ink in each nozzle orifice in addition to wiping ink deposited on the nozzle formation face. Thus, the force of elastically pressing the margin of the wiping material against the nozzle formation face must be set to a soft and appropriate strength to such an extent that the meniscus can be stabilized reliably; this is a first technical demand. 
     The cleaning operation with the rubbing member of the wiper is called “rubbing operation.” The “rubbing operation” has a role of scraping off a foreign substance fixedly secured to the nozzle formation face. Thus, the force of pressing the margin of the rubbing material against the nozzle formation face must be set large to such an extent that the foreign substance fixedly secured to the nozzle formation face can be scraped off; this is a second technical demand. 
     However, hitherto, to meet the first and second technical demands for the wiper, a wiping member easily bent and a rubbing member harder to bend than the wiping member have been used only in combination. Thus, naturally there is a limit and both the technical demands are not easy to meet sufficiently. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the invention to provide an ink jet recording apparatus which has a head maintenance unit for maintaining the jetting characteristic of a recording head and can easily and sufficiently meet the first and second technical demands for the wiping member of the wiper, one of the head maintenance units. 
     To the end, according to a first aspect of the invention, there is provided an ink jet recording apparatus comprising: 
     a recording head; and 
     a wiping unit for wiping a nozzle formation face of the recording head including: 
     a slider reciprocally moving in a direction parallel with the nozzle formation face; 
     a wiper supported by the slider, one end of which is pressed against the nozzle formation face as a wiping operation when the slider moves in a first direction, while as a rubbing operation when the slider moves in a second direction opposed to the first direction; 
     a supporter for rotatably supporting the other end of the wiper on the slider; 
     a spring for urging the wiper toward the nozzle formation face while keeping an attitude of the wiper directed by a reaction force generated when the wiping operation is executed; and a rotation limitter for restricting the rotation of the wiper such that the wiper is rigidly supported by the slider when the rubbing operation is executed. 
     According to the configuration, during the wiping operation, the wiper is pressed against the nozzle formation face of the recording head using the elastic forces of both the wiper itself and the spring, so that the first technical demand that the wiper must be pressed against the nozzle formation face with a soft and appropriate strength to such an extent that a meniscus of ink in the nozzle orifice can be stabilized reliably as compared with the structure in the related art wherein the wiper is pressed by the elastic force of only the wiper itself can be met easily and sufficiently. 
     During the rubbing operation, the rotation limitter restricts rotation of the wiper for placing the wiper in a rigid support state, so that the wiper is strongly pressed against the nozzle formation face and thus the foreign substances fixedly secured to the nozzle formation face can be scraped off reliably; the second technical demand can be met easily and sufficiently. 
     Preferably, the wiper is composite member made of a wiping member which is an elastic plate and a rubbing member made of a material having a higher bending resistance than the wiping member. 
     According to the configuration, the wiping operation is performed with the wiping material appropriate for wiping and the rubbing operation is performed with the rubbing material appropriate for rubbing, so that the spring is also used, whereby the first and second technical demands can be met easily and sufficiently all the more. 
     Preferably, the wiping unit includes: 
     a holder for holding the other end of the wiper and rotatably supported by the slider through the supporter; and 
     an arm member one end of which supports the holder, and the other end of which is-engaged with the slider with a play of a predetermined stroke for absorbing the elastic force of the spring. 
     According to the configuration, the first technical demand can be met as a simple structures. 
     Preferably, the slider has a shaft member fitted into a slot formed at the other end of the arm member so as to be movable within the slot. The movable range of the shaft member corresponds to the play. 
     According to the configuration, the play of the predetermined stroke is provided in the movable range of the slot relative to the shaft body, namely, the spring action range is limited, so that the urging force of the spring can be used stably with a predetermined strength. 
     Preferably, the rotation limitter holds the wiper at one rotational limit position to execute the rubbing operation. 
     According to the configuration, when the wiper is at one rotational limit position, the rubbing operation is performed, so that the wiper cannot be rotated during the rubbing operation and thus a strong press strength can be provided according to a mechanically simple structure. 
     Preferably, the slider includes: 
     a main rack extending in a longitudinal direction of the slider; and 
     a pinion meshed with the main rack and rotating back and forth to reciprocally moving the slider. 
     According to the configuration, the slider is reciprocated by the rack-pinion mechanism, so that the stability of reciprocating the slider can be enhanced as a simple structure. 
     Preferably, the slider indudes a differential rack extending parallel with the main rack and having a first portion and a second portion. The pinion meshes both of the main rack and the differential rack in the first portion to move the slider cooperationally. The pinion meshes only the differential rack in the second portion to reciprocally tilting the wiper. 
     According to another aspect of the invention, the ink jet recording apparatus further indudes a differential rack being placed slidably in the longitudinal direction of the slider, wherein the differential rack is reciprocated in step with the main rack by rotating a pinion meshing with the differential rack in forward and backward directions and wherein at the move termination part of the slider in the forth motion direction, only the differential rack is further pushed out by the pinion and is moved in the forth motion direction, whereby the wiper is tilted in the forth motion direction. 
     Preferably, pitches of the main rack and the differential rack are substantially the same. The number of teeth of the differential rack is larger than the number of teeth of the main rack. 
     According to the configurations, the differential rack enables the wiper to be easily tilted in the forth motion direction after the termination of the wiping operation, whereby the wiper can be restored to the former position without bringing the wiper into contact with the nozzle formation face of the recording head after the termination of the wiping operation. 
     Preferably, the wiping unit includes: 
     a holder for holding the other end of the wiper and rotatably supported by the slider through the supporter; and 
     an arm member one end of which supports the holder, and the other end of which is engaged with the slider with a play of a predetermined stroke for absorbing the elastic force of the spring. 
     According to the configuration, the first technical demand can also be met as a simple structure in the structure using the differential rack. 
     Preferably, the slider has a member fitted into a slot formed at the other end of the arm member so as to be movable within the slot. The movable range of the shaft member corresponds to the play. 
     According to the configuration, the play of the predetermined stroke is also provided in the movable range of the slot relative to the shaft body in the structure using the differential rack, so that the urging force of the spring can be used stably. 
     Preferably, the rotation limitter is established by meshing the pinion with the differential rack. 
     According to the configuration, the differential rack and the main rack are moved in one piece by the pinion in the state in which the pinion, the differential rack, and the main rack mesh with each other at the same time, so that the wiper is restricted in rotation in the forth motion direction. Therefore, the strong press strength during the rubbing operation can also be provided as a simple structure in the structure using the differential rack. 
     Preferably, the ink jet recording apparatus further comprises an ink remover for removing ink adhered onto the wiper after the wiping operation has been executed. A front face of the ink remover is formed such that the wiper is brought into contact therewith gradually when the slider is moved toward the first direction. A rear face of the ink remover is formed such that a force for elastically bending the wiper applied by the front face is released and thereby the wiper is restored rapidly. 
     According to the configuration, ink is removed from the wiper by the ink remover, so that the capability of the wiper can be easily recovered. Preferably, the recovery operation is performed for each wiping operation. Since the ink remover has the front of the shape to allow the wiper to gradually start to come in contact with, splashing of ink can be decreased if the wiper with ink strikes the ink remover. Further, the ink remover has the rear of the shape to allow the wiper to be detached in a stroke after the wiper is bent in an opposite direction to the move direction as it is pressed against the front of the ink remover, so that ink can be splashed from the wiper at the instant at which the wiper is detached, and the capability of the wiper can be recovered reliably. 
     The front shape of the ink remover may be a slope, a face having a large number of asperities, a face formed with an opening at a position opposed to the end margin of the wiper, etc., for example. 
     Preferably, the ink jet recording apparatus further comprises an ink absorber for receiving ink removed and splashed from the wiper by the ink remover. 
     According to the configuration, the ink splashed instantaneously from the wiper can be reliably caught without being leaked to other parts. 
     Preferably, the ink jet recording apparatus further comprises: 
     a capping unit having a capping state in which the capping unit moves toward the recording head to seal the nozzle formation face and a non-capping state in which the capping unit moves away from the recording head to release the sealing of the nozzle formation face; and 
     a unit frame for retaining the wiping unit and the capping unit. 
     The wiping unit reciprocally moves in a space defined between the recording head and the capping unit in the non-capping state. 
     According to the configuration, the wiper is reciprocated in the space in the non-capping state of the capping unit, so that the recorder can be made compact. 
     Preferably, the ink jet recording apparatus further comprises: 
     a cap drive cam for changing a rotational movement thereof into the reciprocal movement of the capping unit between the capping state and the non-capping state; 
     a main rack extending in a longitudinal direction of the slider; 
     a pinion meshed with the main rack and rotating back and forth to reciprocally moving the wiping unit; 
     a drive gear meshed with the pinion to rotate the same; and 
     a shaft member for coaxially supporting the cap drive cam and the drive gear such that the reciprocal movements of the capping unit and the wiping unit are conducted at a predetermined timing. 
     According to the configuration, the drive gear for meshing with the pinion and rotating the pinion and the cap drive cam are placed on one support shaft member for timing reciprocal movement of the wiper and the capping unit, so that control can be simplified. 
     Preferably, the ink jet recording apparatus further comprises: 
     a subframe engaged with a part of the unit frame in a cantilevered manner; and 
     a cam follower, which is to be abutted against the cap drive cam, attached to the subframe. 
     The capping unit is disposed in a free end side of the subframe. 
     According to the configuration, the reciprocal movement of the capping unit can be performed by simple cam control. 
     Preferably, ink jet recording apparatus further comprises a valve drive cam supported by the shaft member coaxially with the drive gear and the cap drive cam. The capping unit includes: 
     a valve member for opening and dosing an internal space of the capping unit; and 
     an operator for operating the open/close state of the valve member, which is operated by the valve drive cam. 
     According to the configuration, the valve member for opening and closing the internal space of the capping unit can be opened and closed as a simple structure by simple cam control. 
     Preferably, ink jet recording apparatus further comprises a suction pump for applying negative pressure in the internal space of the capping unit, and provided in the unit frame to constitute a head cleaning unit together with the wiping unit and the capping unit. 
     According to the configuration, the suction pump, the wiper, and the capping unit make up the head cleaning unit in one piece, so that the head cleaning unit can be made compact and can be easily assembled. 
     Preferably, the wiping unit includes a plurality of units arranged parallel with each other, each composed of a pair of slider and a wiper. The recording apparatus further comprises a selector for selecting one out of all available combinations of the wiping units to be driven. 
     According to the configuration, the ink jet recording apparatus comprises the selector capable of selecting the wiping units to be driven, so that both or either of the wiping operation and the rubbing operation can be executed only for the nozzle array requiring both or either of the wiping operation and the rubbing operation; the efficient operation with no waste can be performed. 
     Preferably, the ink jet recording apparatus further comprises a select cam supported by the shaft member coaxially with the drive gear, the cap drive cam and the valve drive cam. The selector is cooperated with the select cam to execute the selecting operation when the select cam is moved in a first direction which is opposed to a second direction in which the cap drive cam and the valve drive cam operates the capping member and the valve member respectively. The shaft member is rotated in the second direction after the selecting operation has been conducted to drive the selected wiping unit. 
     According to the configuration, selecting a wiping unit and both or either of the wiping operation and the rubbing operation of the selected wiping unit can be easily accomplished by backward and forward rotating one cam support shaft. 
     Preferably, the moving direction of the slider is parallel with an extending direction of an nozzle array on the nozzle formation face. 
     According to the configuration, the wiper is moved in the subscanning direction rather than in the main scanning direction, so that it is less feared that ink may be scattered in the main scanning direction accompanying the wiping operation, and even with a recording apparatus adopting a multicolor head, it is less feared that color inks may be mixed by performing the wiping operation. 
     Preferably, the ink jet recording apparatus further comprises a passage through which a recording medium is transported to be subjected to the recording by the recording head, the passage extending obliquely from a top part of the apparatus to a bottom part of the apparatus. The moving direction of the slider is parallel with the passage and the first direction directs toward the end of the passage. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the accompanying drawings: 
     FIG. 1 is a perspective view to show an ink jet recording apparatus according to the invention; 
     FIG. 2 is a perspective view to show a head maintenance unit according to the invention; 
     FIG. 3 is a schematic side view of the inside of the head maintenance unit with a partly sectioned view and shows a state in which a cam is at a reference position for a home position; 
     FIG. 4 is a schematic plan view of the inside of the head maintenance unit with a partly sectioned view; 
     FIG. 5 is a perspective view of a wiping unit according to the invention to show that a wiping member is in a perpendicular state; 
     FIG. 6 is a bottom plan view of the wiping unit of FIG. 5; 
     FIG. 7 is a perspective view of the wiping according to the invention to show that the wiping member is tilted; 
     FIG. 8 is a bottom plan view of the wiping unit of FIG. 7; 
     FIG. 9 is a bottom perspective view showing a state wherein the wiping unit meshes with a pinion; 
     FIG. 10 is a side view of the inside of the same head maintenance unit as in FIG. 3 to show a state in which a cam shaft is a little rotated from a reference position; 
     FIG. 11 is a side view of the inside of the same head maintenance unit as in FIG. 10 to show a state in which the cam shaft is further a little rotated; 
     FIG. 12 is a side view of the inside of the same head maintenance unit as in FIG. 11 to show a state in which the cam shaft is further a lime rotated; 
     FIG. 13 is a side view of the inside of the same head maintenance unit as in FIG. 12 to show a state in which the cam shaft is further a little rotated; 
     FIG. 14 is a side view of the inside of the same head maintenance unit as in FIG. 13 to show a state in which the cam shaft is further a little rotated; 
     FIG. 15 is a side view of the inside of the same head maintenance unit as in FIG. 14 to show a state in which the cam shaft is further a little rotated; 
     FIG. 16 is a side view of the inside of the same head maintenance unit as in FIG. 15 to show a state in which the cam shaft is a little rotated backward; 
     FIG. 17 is a side view of the inside of the same head maintenance unit as in FIG. 15 to show a state in which the cam shaft is rotated to a point near the termination point; 
     FIG. 18 is a side view of the inside of the same head maintenance unit as in FIG. 17 to show a state in which the cam shaft is rotated to the termination point; 
     FIG. 19 is a side view of the inside of the same head maintenance unit as in FIG. 18 to show a state in which the cam shaft is a little rotated backward from the state in FIG. 18; 
     FIG. 20 is a side view of the inside of the same head maintenance unit as in FIG. 19 to show a state in which the cam shaft is further a little rotated backward from the state in FIG. 19; 
     FIG. 21 is an exploded perspective view of the portion of a drive mechanism section and a capping unit according to the invention; 
     FIG. 22 is a side view of the main part of an ink remover according to the invention; 
     FIG. 23 is a transverse sectional view of the main part of the ink remover according to the invention; 
     FIG. 24 is a transverse sectional view of the main part of different ink remover according to the invention; 
     FIG. 25 is a side view of the main part of different ink remover according to the invention; 
     FIG. 26 is a schematic side view to show selector according to the invention; 
     FIG. 27 is a schematic side view the to show a selector according to the invention in a state in which a selection cam is further rotated; 
     FIG. 28 is an exploded perspective view to show the selector according to the invention; 
     FIG. 29 is a perspective view of selection cam according to the invention viewed from the arrow direction in FIG. 28; 
     FIG. 30 is a rear view to show the selector according to the invention; 
     FIG. 31 is a side view of the main part of the selector according to the invention; 
     FIG. 32 is a perspective view to show the portion of a drive gear and a pinion according to the invention; 
     FIG. 33 is a side view of the main part of the selector according to the invention; 
     FIG. 34 is a side view of the main part of the selector according to the invention; 
     FIG. 35 is a side view of the main part of the selector according to the invention; and 
     FIG. 36 is a side view of the main part of the selector according to the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the accompanying drawings, there are shown preferred embodiments of the invention. FIG. 1 is a perspective view to show an ink jet recording apparatus according to the invention. FIG. 2 is a perspective view to show a head maintenance unit according to the invention. FIG. 3 is a schematic side view with a partly sectioned view of the inside of the head maintenance unit. FIG. 4 is a schematic plan view with a partly sectioned view of the inside of the head maintenance unit. 
     The ink jet recording apparatus is a largesized printer that can also print paper of a comparatively large size such as the paper width 594 mm (A1 in the JIS) or 728 mm (B1 in the JIS). Of course, the invention can be applied not only to such a large-sized printer, but also to a standard-sized printer. 
     As shown in FIG. 1, the ink jet recording apparatus comprises a paper feeder  1 ; a recording section  2 , and a paper discharger  3  positioned from the top to the bottom front. Predetermined printing is executed on paper of a recording medium while the paper is sent from the pap feeder  1  to the recording section  2  to the paper discharger  3 , and ten the paper is discharged to the outside. A paper transport passage  8  at the printing time is formed at an inclination angle of 65 degrees with respect to the horizontal plane. A nozzle formation face of a recording head  54  mounted on a carriage  4  and reciprocated in a main scanning direction along a guide shaft  6  is also disposed at an inclination angle of 65 degrees so as to become parallel with the paper transport passage  8 . The invention is not limited to the recorder of such an inclination structure, of course. 
     A head maintenance unit  30  for maintaining the jetting characteristic of the recording head  54  is disposed in a portion including a home position of the carriage  4 . When the carriage  4  is at the home position, the head maintenance unit  30  performs processing of maintaining the jetting characteristic of the recording head  54 . In FIG. 1, numeral  7  denotes a driving belt for reciprocating the carriage  4  in the main scanning direction, numeral  9  denotes an ink cartridge holder, and numeral  10  denotes a front cover in an open state. 
     As shown in FIG. 2, the head maintenance unit  30  comprises a unit frame  31  made up of both side frames  32  and  33 , an upper frame  34 , etc., and shaped almost like a box. That is, the unit frame  31  contains a wiping unit  35  for wiping the nozzle formation face as required, a capping unit  37  pressed against the nozzle formation face of the recording head  54  at the non-recording time for sealing nozzle orifices, a drive mechanism section  200  for driving the wiping unit  35  and the capping unit  37 , a suction pump  75  for forcibly sucking and discharging ink to remove clogging of the nozzle orifices and mixed air bubbles, an ink remover  55  not shown in FIG.  2  and shown in FIGS. 3 and 4, a selector  300  (FIG.  3 ); etc. The ink remover  55  is adapted to recover the capability of the wiping unit  35  and the selector  300  is adapted to allow the wiping operation, etc., to be performed only for a necessary nozzle array if a multicolor head is adopted. 
     A drive motor  43  for operating the capping unit  37  and a pump motor  44  for operating the suction pump  75  are attached to the side frame  32 . Numeral  45  denotes a gear for transmitting power of the pump motor  44  to the suction pump  75 . 
     The internal structure of the unit frame  31  will be discussed with reference to FIGS. 3 and 4. As shown here, the wiping unit  35 , the capping unit  37 , and the ink remover  66  are disposed in order. The direction in which they are disposed is a direction in which a slider  46  of the wiping unit  35  is reciprocated, and the ink remover  65  is disposed at the termination point of the forth motion. The reciprocating direction of the slider  46  in the embodiment is made slant so as to be compatible with a nozzle formation face  94 ; particularly the forth motion direction of the slider  46  is made parallel with the nozzle formation face  94  and is tilted downward. 
     As shown in FIG. 3, the suction pump  75  and the drive mechanism section  200  are placed below the wiping unit  35 . The roughly whole structure of the drive mechanism section  200  is shown in FIG. 21 as a perspective view in a disassembly state into large element units together with the capping unit  37 . The drive mechanism section  200  uses the drive motor  43  as a power source for enabling the capping unit  37  to take a capping state in which the capping unit  37  goes to the side of the recording head  54  for sealing the nozzle formation face  94  (the state in FIG. 3) and a non-capping state in which the capping unit  37  retreats from the capping state for unsealing the nozzle formation face  94  (the state in FIGS.  11  and  12 ). Further, the drive mechanism section  200  opens and doses a valve  56  in the capping unit  37 , reciprocates the slider  46  of the wiping unit  35 , and controls the selection operation of the selector  300 . 
     As shown in FIG. 4, in the embodiment, to handle a multicolor head, the wiping unit  35  comprises three wiping units each consisting of a pair of one wiper  36  and a slider  46  corresponding thereto. The three wiping units are disposed so that the sides of the wiping members  36  can be swung up and down with the base end side as a supporting point, and the side of each wiper  36  is urged downward by a plate spring (not shown) all the time. The wiping unit is pressed and retained by the plate spring at a constant position where a rack placed on the bottom face of the wiping unit (described later) meshes with a pinion supported on a pinion support frame  130  (described later), separate from the wiping unit. Three ink removers  55  are provided corresponding to the three wiping units and further three sealing caps  38  of the capping unit  37  are also provided. 
     Next the structure of the wiping unit  35  will be discussed in detail with reference to FIGS. 5 to  8 . FIG. 5 is a perspective view of the wiper according to the invention to show that the wiper  36  is supported in an orthogonal state to the reciprocating direction of the slider  46 . The wiper  36  is made of a composite material provided by joining a wiping member  47  made of an elastic plate of rubber, etc., and a rubbing member  48  made of felt, etc., having larger resistance to bend than the wiping member  47 . The base end side of the wiper  36  is strongly clamped by a holder  80  and is attached to a supporter  81  at the tip of the slider  46  via the holder  80  for rotation. 
     The free end side of the holder  80  is supported by an arm  77  and an opposite end part of the arm  77  is retained in a shaft body  82  of a separate body with play of a predetermined stroke. This retention structure is provided by loosely engaging a slot  78  made in the opposite end part of the arm  77  in the shaft body  82 . Therefore, the arm  77  has the play of the predetermined stroke in the limited move range of the slot  78  relative to the shaft body  82 , whereby the wiper  36  can be rotated in the range corresponding to the movable distance of the slot  78  relative to the shaft body  82 . 
     If the shaft body  82  is fixed to the slider  46 , the range in which the wiper  36  can be rotated is limited to the move range of the slot  78  relative to the shaft body  82 . Specifically, the wiper  36  is mechanically restricted in rotation in the forth motion direction from the orthogonal state to the slider  46  shown in FIG.  5  and cannot be tilted, and this position becomes the rotation limit in the forth motion direction. This state is used in the rubbing operation described later. 
     A coil spring  49  is placed in a compression state between a base body  84  to which the shaft body  82  is fixed and a coupling part  83  of the left and right of the arm  77 , and the wiper  36  receives the urging force of the coil spring  49  in the move range of the slot  78  relative to the shaft body  82 , namely, the range in which the wiper  36  can be rotated. The strength of the coil spring  49  is set so that at the wiping operation time, the wiper  36  receiving the reaction involved in pressing the wiper  36  against the nozzle formation face  94  and rotated in the direction of the reaction is urged in the pressing direction in the state intact and is supported by both the elastic force of the wiper  36  itself and the elastic force of the coil spring  49 . 
     In the embodiment, the base body  84  to which the shaft body  82  is fixed is not fixed to the slider  46  and is fixed to a base body  50  (FIG. 6) of a differential rack  86  that can be moved relatively to the slider  46 . Therefore, the differential rack  86  can be moved with respect to the slider  46 , so that the wiper  36  can be further moved in the forth motion direction of the slider  46 . FIG. 7 shows a state in which the wiper  36  is rotated further largely exceeding the rotation range of the wiper  36  corresponding to the move range of the slot  78  relative to the shaft body  82 . That is, the differential rack  86  is further moved with the slider  46  stopped, whereby the wiper  36  can be tilted largely in the forth motion direction. 
     FIG. 6 is a bottom plan view of the wiping unit  35  when the wiping unit  35  in the state in FIG.  5 . The slider  46  is formed with a main rack  85  along the longitudinal direction of the slider  46  and is reciprocated as a pinion  52   a,    52   b,    52   c  (see FIG. 9) meshing with the main rack  85  is rotated in forward and backward directions. 
     The base  50  having the differential rack  86  is further provided so that the wiping unit becomes slidable in the longitudinal direction of the slider  46 . The differential rack  86  is reciprocated in step with the main rack  85  as the pinion  52   a,    52   b,    52   c  meshing with the differential rack  86  is rotated in the forward or backward directions. The mesh state of the pinion  52   a,    52   b,    52   c  with the main rack  85  terminates in the move termination part of the slider  46  in the forth motion direction and after the slider  46  stops, the differential rack  86  still maintains the mesh state with the pinion,  52   a,    52   b,    52   c  and only the differential rack  86  is further pushed out and is moved in the forth motion direction. 
     Specifically, the rack pitches in the main rack  85  and the differential rack  86  we almost the same as shown in FIG.  6  and the number of rack teeth made in the differential rack  86  is greater than that of rack, teeth made in the main rack  85  by three. FIG. 6 shows a state in which the differential rack  86  is not pushed out with respect to the main rack  85 , and a tooth  88  positioned at the extreme tip on the side of the differential rack  86  is arranged at the same position as a tooth positioned at the extreme tip on the side of the main rack  85 . On the other hand, a tooth  87  positioned at the extreme rear end on the side of the differential rack  86  extends off a tooth positioned at the extreme rear end on the side of the main rack  85  by three pitches backward. Thus, after the slider moves to and stops at the position where the mesh of the tooth at the extreme rear end of the main rack  85  with the opinion is released, the differential rack  86  can be further moved by the distance corresponding to the three teeth at the termination part. As only the differential rack  86  is moved, the wiper  36  is rotated and can be tilted largely in the forth motion direction as shown in FIG.  7 . 
     FIG. 8 is a bottom plan view of the wiping unit of the wiping unit  35  when the wiping unit in the state in FIG.  7 . The differential rack  86  is pushed out with respect to the main rack  85  and the tooth  88  positioned at the extreme tip on the side of the differential rack  86  extends off the tooth positioned at the extreme tip on the side of the main rack  85  by three pitches forward. On the other hand, the tooth  87  positioned at the extreme rear end on the side of the differential rack  86  is arranged at the same position as the tooth positioned at the extreme rear end on the side of the main rack  85 . 
     In this state, if the pinion is meshed with the main rack  85  and the differential rack  86  and is rotated backward, the corresponding wiping unit is moved back with the wiper  36  tilted as shown in FIG.  7 . After the slider is moved back to and stops at the position where the mesh of the tooth at the extreme tip of the main rack  85  with the opinion is released, the differential rack  86  can be further moved by the distance corresponding to the three teeth extending to the tip end side including the tooth  88  at the extreme tip (FIG.  8 ). As only the differential rack  86  is moved back, the wiper  36  is rotated in the back motion direction and is restored to the orthogonal state to the slider  46  as shown in FIG.  5 . 
     If the pinion  52   a,    52   b,    52   c  meshes with both the racks  85  and  86  in the state shown in FIG. 5, namely, FIG. 6 in the structure in the embodiment wherein the base body  84  to which the shaft body  82  is fixed is fixed to the base body  50  of the differential rack  86 , the wiping member is restricted in rotation in the forth motion direction from the orthogonal state. The reason is that as both the racks and the pinion mesh with each other simultaneously, both the racks are moved in one piece and a move of only the differential rack is not made. Therefore, the position becomes the rotation limit in the forth motion direction. This state is used in the rubbing operation. 
     FIG. 9 is a perspective view of the wiping unit  35  when the wiping unit  35  meshing with the pinion is viewed from the bottom. The three pinions  52   a,    452   b,  and  52   c  are provided in a one to one correspondence with the three wiping units (see FIG.  4 ). 
     Next, referring again to FIGS. 3 and 4, the ink remover will be discussed. The ink remover  56  for removing ink from the wiper  36  is placed at a position immediately after the wiping operation range. The ink remover  55  has a front  107  of a shape to allow the wiper  36  to gradually start to come in contact with when the slider  46  is moved in the wiping operation direction and a rear  108  of a shape to allow the wiper  36  to be detached in a stroke after the wiper  36  is bent in an opposite direction to the move direction as it is pressed against the front  107 . 
     As the shape of the front  107  of the ink remover  55 , a face  109  having a large number of asperities shown in FIG. 24, a face formed with an opening at a position opposed to the end margin of the wiper  36 , and the like are named in addition to slopes shown in FIGS. 4,  22 , and  23 . 
     In any case, the shape of the rear  108  is made a flat shape orthogonal to the travel direction of the wiper  36 . 
     Since the ink remover  55  removes ink  106  from the wiper  36 , the capability of the wiper  36  can be recovered. Preferably, the recovery operation is performed for each wiping operation. The ink remover  55  has the front  107 ,  109 ,  110  of the shape to allow the wiper  36  to gradually start to come in contact with. Thus, if the wiper  36  on which the ink  106  is deposited strikes the ink remover  55 , scattering of the ink  106  can be decreased. Further, the ink remover  55  has the rear  108  of the shape to allow the wiper  36  to be detached in a stroke after the wiper  36  is bent in the opposite direction to the move direction as it is pressed against the front  107 ,  109 ,  110  of the ink remover  55 , so that the ink  106  can be splashed from the wiper  36  at the instant at which the wiper  36  is detached, and the capability of the wiper  36  can be recovered reliably. 
     Further, in the embodiment, as shown in FIGS. 3 and 4, an ink absorber  41  is provided for receiving ink drops splashed from the wiper  36  by the ink remover  55 . The ink absorber  41  is held in a holder  40 . According to the invention, the ink splashed instantaneously from the wiper  36  can be reliably caught without being leaked to other parts. 
     Next, the capping unit  37  and the drive mechanism section  200  will be discussed with reference to FIGS. 3,  10 ,  12 , and  21 . 
     First, the capping unit  37  comprises sealing caps  38  on the top of a main body  141  and can be moved to and from the recording head  54  with a pair of left and right guides  142  (FIG. 21) guided on a pair of guide receptacles  39  provided on the side frames  32  and  33 . The capping unit  37  also comprises the valve  56  for opening and closing the internal space of the main body  141 , and a valve actuator  67  placed in the bottom part of the main body  141  is pulled in a direction away from the bottom of the main body, whereby the valve  56  is changed tom a dosed valve state to an open valve state. The valve actuator  57  is driven by a valve drive cam  62  described later. 
     The drive mechanism section  200  for controlling moving the capping unit  37  to and from the recording head  54  and opening and closing the valve  56  is made up of a cam body  143  and a subframe  92  swung up and down with the base end as a supporting point by the action of the cam body  143 , as shown in FIG.  21 . 
     The cam body  143  comprises a valve drive cam  62  having a short perimeter and a cap drive cam  64  having a long perimeter, the valve drive cam  62  and the cap drive cam  64  placed contiguously in the circumferential direction on an outer peripheral surface  61  of a small-diameter shaft  60  shaped like a cylinder. The valve drive cam  62  and the cap drive cam  64  are shifted in position in the axial direction of the small-diameter shaft  60 , as shown in FIG. 21. A convex curved surface  63  to the cap drive cam  64  from the termination positions of the valve drive cam  62  is also a cam face having one function described later. A position on the outer peripheral surface  61  of the small-diameter shaft  60  and just before the valve drive cam  62  is used as a cam control reference position  65  and when the reference position  65  is placed as shown in FIG. 3, the cam body  143  is set to the initial position on control of the cam body  143 . 
     The subframe  92  is attached on a base end  105  to the lower part of the base end of the unit frame  31  shown in FIG. 2 (portion pointed to by an arrow  500 ) so that it can be swung up and down across both the side frames  32  and  33  with an opposite end side as a free end  140  with the base end  105  as a supporting point. The subframe  92  has the free end  140  urged upward by a long coil spring  42 , as shown in FIG.  21 . 
     A cam follower  91  of the cap drive cam  64  is provided at the center of the bottom portion of the subframe  92 . The cam follower  91  is formed as a roller structure rotated freely. A lever  66  which has a supporting point  67  at a position to the base end of the bottom portion of the subframe  92  and can be  6  rotated up and down is provided. A cam follower  71  of the valve drive cam  62  is placed at a position adjacent to the cam follower  91  of the lever  66 . Further, a hand part  70  is placed at the tip of the lever  66 . 
     The capping unit  37  is coupled at the bottom integrally with a coupling frame  144  provided on the side of the free end  140  of the subframe  92 , whereby the capping unit  37  moves in association with swinging of the subframe  92  and is moved to and retracted from the recording head  54 . In the couple state, the hand part  70  of the lever  66  is retained in the valve actuator  57  of the capping unit  37  and in this state, the lever  66  is pushed down for making a pull down force act on an actuated part  58  of the valve actuator  57 , whereby the valve unit  56  is changed from a closed valve state to an open valve state. Numeral  68  denotes the tip of the lever  66  and the tip  68  is joined to the base end side by a joint part  69  for rotation. 
     Next, the relationship between the wiping unit  35  and the drive mechanism section  200  will be discussed with reference to FIGS. 3,  14 ,  21 , and  32 . The slider  46  of the wiping unit  35  is reciprocated by the rack-pinion mechanism of the pinion  52   a,    52   b,    52   c,  the main rack  85 , and the differential rack  86 , as described above. In the embodiment, the pinion  52   a,    52   b,    52   c  is rotated by the drive mechanism section  200 . 
     Rotation power is transmitted to the pinion  52   a,    52   b,    52   c  from a drive gear  100  formed in a part on the outer peripheral surface of a drive wheel  101 . The drive wheel  101  is attached to the unit frame  31  coaxially with the cam body  143 , as shown in FIGS. 3 and 14. Specifically, the cam body  143  shown in FIG. 21 is fitted to a shaft  129  of the drive wheel  101  shown in FIG. 32 in one piece and the cam body  143  and the drive wheel  101  are rotated in one piece around a common shaft with the motor  43  as a drive source. 
     FIG. 3 shows a state in which the drive gear  100  does not mesh with the pinion  52   a,    52   b,    52   c  and FIG. 14 shows a state in which the drive gear  100  meshes with the pinion  52   a,    52   b,    52   c.  If the drive wheel  101  is rotated in the state in which the drive gear  100  meshes with the pinion  52   a,    52   b,    52   c,  the slider  46  of the wiping unit  35  is reciprocated; if the drive wheel  101  is rotated in the state in which the drive gear  100  does not mesh with the pinion  52   a,    52   b,    52   c,  the slider  46  stops. 
     In the embodiment, as the phase in the rotation direction with both the cam body  143  and the drive wheel  101  in one piece, as shown in FIG. 14, when the subframe  92  is pushed downward by the cap drive cam  64  and the capping unit  37  is retreated from the recording head, the drive gear  100  and the pinion  52   a,    52   b,    52   c  are meshed with each other. Therefore, a space  93  produced below the nozzle formation face  94  of the recording head  54  as the capping unit  37  is retreated from the recording head  54  can be used effectively as a space for the wiping operation. 
     As shown in FIG. 32, the pinions  52   a,    52   b,  and  52   c  use a common shaft  135  and the shaft  135  is journaled at both ends by the pinion support frame  130 , whereby the shaft  135  is supported on the pinion support frame  130  for rotation. Further, the pinion support frame  130  is attached around the common shaft to the cam body  143  and the drive wheel  101  so that it can be pulled and a little rotated by contact friction with rotation of the cam body  143  and the drive wheel  101 . The pinion support frame  130  is formed on one side with a projection  131  and the projection  131  is inserted and held in a hole (not shown) made in the side frame  33  with a slight clearance in the rotation direction of the pinion support frame  130 . 
     Therefore, the pinion  52   a,    52   b,    52   c  can be moved as the pinion support frame  130  is a little rotated. The reason is as follows: When the pinion  52   a,    52   b,    52   c  is meshed with the main rack  85  and the differential rack  86  and is sent in one direction, if it is sent also using the last tooth of the rack, the pinion is detached from the last tooth of the rack at the sending termination time. Therefore, if the pinion is rotated backward, it cannot be meshed with the rack and thus the back motion cannot be made. Then, the pinion is moved a little, so that it can be meshed with the last tooth of the rack, whereby if the pinion is sent also using the last tooth of the rack, the back motion can be made easily. 
     Next, the wiping operation and the rubbing operation in the ink jet recording apparatus will be discussed with reference to FIGS. 3 and 10 to  20 . FIG. 3 shows a state in which the capping unit  37  goes to the recording head  54  and seals the nozzle formation face  94 . The drive mechanism section  200  is at the initial position. The drive motor  43  is driven for rotating the cam body  143  and the drive wheel  101  around the command shaft in one piece. 
     FIG. 10 shows the first cam control state in which the cam body  143  is a little rotated from the initial position and the valve drive cam  62  pushes down the lever  66  through the cam follower  71 , whereby the valve  56  is changed from a closed state to an opened state. At this time, the subframe  92  does not move and thus the capping unit  37  remains sealing the nozzle formation face  94  of the recording head  54 . 
     FIG. 11 shows a state in which the cam body  143  is further a little rotated and the convex curved surface  63  existing before the cap drive cam  64  abuts against the cam follower  91 , thereby lowering the subframe  92  a little. Thus, the capping unit  37  comes off the nozzle formation face  94  of the recording head  54 . In this state, the record operation is executed in the recording section  2 . At this time, the valve drive cam  62  is detached from the cam follower  71  and thus the valve  56  is restored to the closed valve state. 
     FIG. 12 shows a state in which the cam body  143  is further a little rotated and the tip of the cap drive cam  64  abuts the cam follower  91 , thereby further lowering the subframe  92 . Thus, the capping unit  37  is retreated largely from the recording head  54  and the space  93  that can be used for the wiping operation is produced below the nozzle formation face  94 . 
     FIG. 13 shows a state in which the drive gear  100  of the drive wheel  101  starts to mesh with the pinion  52   a,    52   b,    52   c  and the slider  46  starts to move in the forth motion direction. 
     FIG. 14 show a state in which the drive wheel  101  is further rotated, the slider  46  is further moved, and the wiping operation is performed for the nozzle formation face  94  of the recording head  54 . 
     As previously described with reference to FIGS. 5 to  8 , the wiper  36  is pressed against the nozzle formation face  94  of the recording head  54  using the elastic forces of both the wiper  36  and the coil spring  49 , so that the wiper  36  can be pressed against the nozzle formation face  94  with a soft and appropriate strength to such an extent that a meniscus of ink in the nozzle orifice can be stabilized reliably as compared with the structure in the related art wherein the wiping member is pressed by the elastic force of only the wiping member itself. 
     FIG. 15 shows a state in which the wiping operation terminates and further the capability of the wiper  36  is recovered by the ink remover  55 . The capability recovery operation of the wiper  36  executed by the ink remover  55  was previously described with reference to FIGS. 22 to  25 . 
     FIG. 16 shows a state in which the drive gear  100  is rotated backward from the state shown in FIG. 15 for moving the slider  46  back and the rubbing operation is performed for the nozzle formation face  94 . 
     At this time, as previously described with reference to FIGS. 5 to  8 , rotation of the wiper  36  is restricted by the rotation limitter and is supported rigidly, so that the tip margin of the wiping member is strongly pressed against the nozzle formation face  94  in a perpendicular state and the foreign substances fixedly secured to the nozzle formation face  94  can be scraped off reliably. The rubbing operation is not always executed following the wiping operation and can be executed whenever necessary. 
     FIG. 17 shows a state in which the drive gear  100  is further rotated forward from the state shown in FIG.  15  and the slider  46  is sent to the position at which the mesh state of the main rack  85  with the pinion terminates, and stops, then only the differential rack  86  is moved forth because of the mesh of the differential rack  86  with the pinion for largely rotating and tilting the wiper  36  in the forth motion direction. 
     FIG. 18 shows a state in which the drive wheel  101  is further a little rotated forward and a selection cam of the selector  300  (described later) is reset. 
     FIG. 19 shows a state in which the drive wheel  101  is rotated backward from the state in FIG.  18  and continues to be rotated backward by meshing the drive gear  100  with the pinion, thereby moving the slider  46  back with the wiper  36  tilted as shown in the figure. The reason why the slider  46  can be moved back with the wiper  36  tilted is that the number of the teeth of the differential rack  86  is made greater than that of the teeth of the main rack  85 , as shown in FIGS. 6 and 8. That is, as shown in FIG. 8, if the pinion is rotated backward with the differential rack  86  sent ahead of the main rack  85 , both the racks  85  and  86  are sent back together by the common opinion in the relation intact, thus the wiper  36  is moved back as it remains tilted, whereby the wiping operation can be terminated without bringing the wiper  36  into contact with the nozzle formation face  94  where the wiping operation is complete. 
     FIG. 20 shows a state in which the wiper  36  passes through below the recording head  36  and is being restored to the orthogonal state to the slider  46 . As shown in FIG. 19, the slider  46  and the differential rack  86  are moved back together, when the slider  46  moves over the distance as much as the full length of the main rack  85  and the mesh of the termination of the main rack  85  with the pinion is terminated, the slider  46  stops moving. At this point in time, however, the differential rack  86  still meshes with the pinion, as seen in FIG.  8 . Therefore, only the differential rack  86  continues moving back as the slider  46  stops. As only the differential rack  86  moves back, the tilted wiper  36  rotates with the supporter  81  as the supporting point and is restored to the orthogonal state. When the wiper  36  has been restored to the orthogonal state, the mesh of the tooth  88  at the termination of the differential rack  86  with the pinion terminates and the differential rack  86  stops moving. At this point in time, the mesh state of the drive gear  100  with the pinion also terminates. After this, the drive wheel  101  rotates, but the pinion does not rotate. Since the cam body  143  also rotates integrally with the drive wheel  101 , the transition from the state in FIG. 13 to the state in FIG. 10 is made reversing the cam operation previously with reference to FIGS. 10 to  13 , and finally a return is made to the initial state shown in FIG.  3 . 
     Next, the relationship between the selector  300  and the drive mechanism section  200  will be discussed with reference to FIGS. 26 to  31 ,  33  to  36 . As already described, in the embodiment, to handle a multicolor heed, the wiping unit  35  comprises three units each consisting of a pair of one wiper  36  and a slider  46  corresponding thereto, as shown in FIG.  4 . Since variations in the jetting characteristics of the three wiping units normally are not uniform, the timing at which the wiping operation becomes necessary varies. Therefore, if only the wiping unit having the wiper  36  corresponding to the head part of the nozzle train requiring the wiping operation is reciprocated and others are stopped, waste is eliminated. 
     The selector  300  can select and drive only the necessary wiping unit; it can be select one to three wiping units to be drive in any combination. 
     As shown in FIG. 28, which is an exploded perspective view, the selector  300  comprises the above-described drive wheel  101 , a selection cam  111  journaled by the shaft  129  of the drive wheel  101  (FIG.  32 ), three selection levers  72 ,  172 , and  272  each having a cam follower corresponding to the selection cam  111 , and a reset lever  122  for resetting the selection levers  72 ,  172 , and  272 . In FIG. 28, the shaft  129  is not shown. 
     As shown in FIG. 28, the selection cam  111  has a first cam part  126 , a second cam part  127 , and a third cam part  128  into which the outer peripheral surface shaped like a cylinder is divided functionally in the circumferential direction. As shown in FIG. 28, the first cam part  126  corresponds to the selection lever  72 , the second cam part  127  corresponds to the selection lever  172 , and the third cam part  128  corresponds to the selection lever  272 . 
     The first cam part  126  has three cam grooves  112 ,  113 , and  114  spaced from each other in the circumferential direction. The second cam part  127  has cam grooves  123  and  124  spaced from each other in the circumferential direction. The third cam part  128  has a cam groove  125 . The cam groove  124  is formed on one end side in the circumferential direction partially at the position as the cam groove  112  and is formed on an opposite end side partially at the same position as one end side of the cam groove  125 . The center of the cam groove  125  in the circumferential direction is formed at the same position as the cam groove  113  and an opposite end part of the cam groove  125  is formed solely at a different position from other grooves. As shown in FIG. 29, the cam grooves  114  and  123  are also solely at different positions from other grooves. The cam grooves are thus placed, whereby any one of the wiping units can be selected or the wiping units can be selected in any combination with the cam follower (described later) in combination, so that the wiping unit to be driven can be selected whenever necessary. 
     The selection cam  111  is journaled by the shaft  129  of the drive wheel  101  (FIG.  32 ), and is disposed between the drive wheel  101  and the cam body  143 . In FIG. 3, the selection cam  111  is at a position behind the cam body  143  and is hidden. 
     As shown in FIG. 28, a rib  115  for retention is projected on the face of the selection cam  111  opposed to the drive wheel  101 , and a projection  117  is formed on the drive wheel  101 . As the drive wheel  101  is rotated counterclockwise in FIGS. 26 and 28, the projection  117  is retained in the rib  115  of the selection cam  111  and presses the rib  115 , whereby the selection cam  111  is rotated together with the drive wheel  101 . 
     A projection  116  for retention is formed on the outer peripheral surface of the selection cam  111 . A stopper  119  provided at the tip of an arm (not shown) fixed to the inner face of the side frame  33  is placed at a position shown in FIG.  26 . When the selection cam  111  is rotated clockwise in FIG. 26, the projection  116  for retention is retained in the stopper  119  and the selection cam  111  is stopped at the retention position in the stopper  119  in the clockwise rotation. 
     The cam grooves made in the first cam part  126 , the second cam part  127 , and the third cam part  128  of the selection cam  111  are shaped so that when the selection cam  111  is rotated counterclockwise, retention parts of cam followers  120 ,  220 , and  320  of the selection levers  72 ,  172 , and  272  (described later) abut and engage the cam grooves and the outer peripheral surface of the selection cam  111  in order to allow the selection cam  111  to be rotated and so that when the selection cam  111  is rotated clockwise, the selection cam  111  is restricted in rotation in a state in which the retention part of each cam follower  120 ,  220 ,  320  engages the cam groove. At this time, the selection cam  111  is stopped and only the drive wheel  101  is rotated clockwise. 
     Further, the selection cam  111  comprises a return spring (not shown) and is assembled in a state in which it receives a clockwise urging force in FIG. 26 by the return spring. Therefore, when the selection cam  111  is released from the restriction force to the rotation position by the rotation force from the projection  117  of the drive wheel  101  and the cam follower of the selection lever  72 ,  172 ,  272  (described later), the selection cam  111  is rotated clockwise in FIG. 26 by the spring force of the return spring, the projection  116  for retention is retained in the stopper  119 , and the selection cam  111  is held in the state. FIG. 26 shows this state. The state in which the retention projection  116  of the selection cam  111  is retained in the stopper  119  and the projection  117  of the drive wheel  101  is retained in the rib  116  on the selection cam  111  is the reference position on operation control of the selection cam  111 , namely, the initial position. 
     As shown in FIGS. 28 to  30 , the selection levers  772 ,  172 , and  272  comprise the first cam follower  120 , the second cam follower  220 , and the third cam follower  320  engaging the cam grooves of the first cam part  126 , the second cam part  127 , and the third cam part  128  of the selection cam  111 . The selection levers  72 ,  172 , and  272  can be swung around a support point shaft  73  placed on the side frames  32  and  33  and each tip operation part  74  receives an upward force produced by the urging force of a spring  76  placed on the base end side. 
     FIG. 26 shows a state in which all the retention parts of the first cam follower  120 , the second cam follower  220 , and the third cam follower  320  of the selection levers  72 ,  172 , and  272  are detached from the cam grooves of the selection cam  111  and abut and engage the uniform outer peripheral surface. This state is a state in which the tip operation part  74  of each of the selection levers  72 ,  172 , and  272  is retreated downward against the urging force of the spring  76 . This retreat state corresponds to a state in which the tip operation part  74  does not abut the bottom face of each wiping unit of the wiping unit  35  (in the embodiment, the bottom face of the slider). 
     Therefore, in this state, the wiper  36  of each wiping unit is lowered to a downward restriction position by a plate spring (not shown), thus the main rack  85  and the differential rack  86  of the wiping unit maintain the mesh state with the pinion  52   a,    52   b,    52   c.  This corresponds to a state in which all the three wiping units shown in FIG. 4 are actuated from the viewpoint of the wiping operation. 
     FIG. 27 shows a state in which a retention part  121  of the first cam follower  120  of the selection lever  72  and a retention part of the second cam follower  220  of the selection lever  172  (in FIG. 27, the retention part overlaps the retention part  121  and does not appear) are engaged in the am groove,  112  of the first cam part  126  and the cam groove  124  of the second cam part  127  at the same position as the cam groove  112  at the same time, whereby the tip actuation parts  74  of the selection levers  72  and  172  are advanced upward by the urging forces of the springs  76 . The advance distance corresponds to the distance of the retention part  121  entering the cam groove. On the other hand, the selection lever  272  has a retention part  321  engaged on the outer peripheral surface rather than in the cam groove of the selection cam  111 , thus the tip operation part  74  corresponding to the selection lever  272  does not abut the bottom face of the corresponding wiping unit as described above. 
     In this state, the main rack  85  and the differential rack  86  of the wiping unit corresponding to each of the selection levers  72  and  172  do not mesh the pinion  52   a,    52   b,  thus only the wiping unit corresponding to the selection lever  272  is operated and reciprocated and other wiping units do not operate from the viewpoint of the wiping operation. 
     The positions of the first cam follower  120 , the second cam follower  220 , and the third cam follower  320  differ from the relative positions of the selection levers  72 ,  172 , and  272 , and are localized side by side to the drive wheel  101 , as shown in FIG. 30 The positions of the localized cam followers correspond to the occupation widths of the first cam part  126 , the second cam part  127 , and the third cam part  128  of the selection cam  111 , making it possible to design the width of the selection cam  111  small. 
     Further, at a position most to the side of the drive wheel  101 , the reset lever  122  is placed on the support point shaft  73  formation, as shown in FIG.  30 . The reset lever  122  is provided for resetting the selection state of the selection lever  72 ,  172 ,  272 . In the embodiment, the reset state is the state shown in FIG. 26 in which the first cam follower  120 , the second cam follower  220 , and the third cam follower  320  are detached from the cam grooves of the selection cam  111  and abut and engage the uniform outer peripheral surface. Therefore, the reset state corresponds to the selection state in which all the three wiping units are actuated from the viewpoint of the wiping operation. 
     The initial position of the selection operation of the selector  300  is set where the selection cam  111  and the drive wheel  101  are placed in the state shown in FIG. 26, as described above. That is, the state in which the retention projection  116  of the selection cam  111  is retained in the stopper  119  and the projection  117  of the drive wheel  101  is retained in the rib  115  on the selection cam  111  is the initial position on selection operation control of the selection cam  111 . 
     The selector  300  in the initial position state shown in FIG. 26 is fitted to the drive mechanism section  200  with the selection cam  111  positioned behind the cam body  143  of the drive mechanism section  200  in the initial position state shown in FIG.  3 . Since the selector  300  is thus fitted to the drive mechanism section  200 , if the cam body  143  is rotated in an opposite direction to the forward rotation direction (clockwise) for actuating the valve drive cam  62  and the cap drive cam  64  from the initial position of the cam body  143  shown in FIG. 3, the selection cam  111  is pressed by the projection  117  of the drive wheel  101  and is rotated in association. At this time, the valve drive cam  62  and the cap drive cam  64  do not abut or engage the cam follower  71 ,  91 , so that a non-actuation state is entered. 
     Therefore, the wiping unit selection operation can be executed by using other portions than the portion of the valve drive cam  62  and the cap drive cam  64  of one cam body  143  with no waste and actuating only the selection cam  111  without actuating the valve drive cam  62  or the cap drive cam  64 . 
     Specifically, the initial position state in FIGS. 3 and 26 is a state in which the three wiping units perform the wiping operation. If the cam body  143  is rotated clockwise in the state, the three wiping units start the wiping operation following the retreat operation of the capping unit  37 , etc., as previously described with reference to FIGS. 3 and 10 to  20 . On the other hand, if the cam body  143  is first rotated counterclockwise from the initial position state in FIGS. 3 and 26, the selection operation is executed preceding the wiping operation. 
     After predetermined selection operation is performed by the selection cam  111 , the cam body  143  is forward rotated clockwise. At this time, the selection cam  111  is restricted in clockwise rotation by engagement with any one or two of the cam followers  120 ,  220 , and  320  of the selection levers  72 ,  172 , and  272 , so that the selection state is maintained. Only the wiping unit thus selected executes the wiping operation. 
     Next, the function of the selector  300  will be discussed with reference to FIGS. 31 and 33 to  36 . FIG. 31 shows the selector  300  in the same initial position state as in FIG.  26 . The selector  300  corresponds to the initial position state for the wiping operation of the cam body  143  shown in FIG. 3 in the relationship with the cam body  143 . 
     If the cam body  143  is rotated counterclockwise in the state, the projection  117  of the drive wheel  101  rotated integrally with the cam body  143  presses the rib  115  on the side of the selection cam  111  for counterclockwise rotating the selection cam  111  against the urging force of the return spring (not shown), whereby any one or two of the cam followers  120 ,  220 , and  320  of the selection levers  72 ,  172 , and  272  previously selected are engaged in the cam grooves of the selection cam  111 . 
     FIG. 33 shows a state in which the cam followers  120  and  220  of the selection levers  72  and  172  are engaged in the cam grooves  112  and  124  at the same time and only the cam follower  320  of the selection lever  272  abuts and engages the outer peripheral surface of the selection cam  111 . The tip operation parts  74  of the selection levers  72  and  172  rise, pushing up the wipers  36  of the corresponding wiping units  35 , whereby the rack-pinion mesh state is released. Thus, if the pinion is rotated, the corresponding wiping unit is placed in a non actuation state. 
     On the other hand, in FIG. 33, only the wiping unit corresponding to the selection lever  272  having the cam follower  320  not engaging the cam groove of the selection cam  111  executes the wiping operation because the rack-pinion mesh state is maintained. 
     Upon completion of the selection operation, the cam body  143  and the drive wheel  101  are rotated clockwise. FIG. 34 shows this state. Thus, the cam body  143  returns to the initial position shown in FIG.  3  and if the cam body  143  is further rotated clockwise, opening/closing the valve  56 , the suction operation of the suction pump  75 , the retreat operation of the capping unit  37  from the recording head  54 , the wiping operation, and the ink removal operation of the ink remover  55  from the wiper  36  are executed and further the rubbing operation is executed as required, as previously described with reference to FIGS. 3 and 10 to  20 . 
     In the embodiment, as shown in FIG. 35, the selection lever  72 ,  172  is reset with the reset lever  122  as follows: The drive wheel  101  is provided with a reset cam  118  as shown in FIG.  28 . If the drive wheel  101  is further rotated clockwise together with the cam body  143  from the state shown in FIG. 17 in which the wiping unit is moved forth for performing the wiping operation and the wiper  36  is tilted in the forth motion direction, the reset cam  118  presses and turns the reset lever  122 . 
     As the reset lever  122  is turned by the reset cam  118 , the cam follower  120 ,  220  is released from the retention state in the cam groove, whereby the selection cam  111  has the retention projection  116  returned instantaneously to the position abutting the stopper  119  by an urging force  132  of the return spring (not shown). FIG. 35 shows this state. 
     After this, the drive wheel  101  is rotated counterclockwise and the projection  117  is abutted against the rib  115  of the selection cam  111  returned to the former position and is stopped. FIG. 36 shows this state. Thus, the drive mechanism section  200  and the selector  300  return to the initial position state shown in FIGS. 3 and 26. 
     Although the present invention has been shown and described with reference to specific preferred embodiments, various changes and modifications will be apparent to those skilled in the art from the teachings herein. Such changes and modifications as are obvious are deemed to come within the spirit, scope and contemplation of the invention as defined in the appended claims.