Abstract:
An ink jet recording head in which a flat plate section has a recess section in its surface and an orifice plate having a plurality of openings grouped and disposed for ejecting a liquid is placed in the recess section, with the flat plate section being cleaned by a cleaning member movable perpendicularly to a direction of the disposition of the ejecting openings in a state brought into contact with a surface of the flat plate section. The recess section includes a combined curved surface made in a manner that a first curved surface having a first curvature and a second curved surface having a second curvature smaller than the first curvature are combined at a position corresponding to the deepest portion of the recess section. At this time, the first curved surface is located on the upstream side of the second curved surface in a cleaning direction of the cleaning member, and the combined curved surface extends in the disposition direction of said ejecting openings. The recess section further includes two inclined surfaces formed at both end portions of the combined curved surface to develop from the surface of the flat plate section. The two inclined surfaces are positioned to be separated by predetermined distances from both end portions of the grouped ejecting openings, respectively. This construction can reduce the ink residual on the recording head after the wiping by the cleaning member.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an ink jet recording head and an ink jet recording apparatus which perform recording by ejecting (discharging) an ink toward a record material. The invention is applicable to systems such as a word processor having a facsimile and printer section equipped with a printer, a copying machine and a communication system, which conducts the recording on record mediums such as paper, yarns, fibers, dishcloth, leather, metals, plastics, glasses and ceramics, and additionally applicable to an industrial recording apparatus involving a composite combination thereof with various types of processing units. In the invention, the “recording” signifies not only that meaningful images such as letters and figures are recorded on a record medium, but also that unmeaningful images such as patterns are recorded thereon. 
     2. Description of the Related Art 
     An ink jet recording apparatus is made to form an image of an ink dot pattern by supplying an ink to an ink jet recording head (which will be referred to hereinafter as a head) and by driving an ink droplet ejecting means such as a piezo device or an electrothermal converter, situated on the head, in accordance with image data. 
     In the case of color printing, a head is provided, for example, for each of yellow, Magenta, cyanogen and block inks, and in the case of a scanning type recording apparatus, these heads are mounted on a carriage which reciprocates along a record medium in predetermined directions. In a color recording apparatus, the heads for the respective colors are disposed in carriage moving directions (main scanning directions). 
     There is a problem which arises with the above-mentioned construction, however, in that the number of heads for the color recording increases so that the cost of the head unit increases and, additionally, so that the recording apparatus tends to increase in size. 
     FIG. 11 is a perspective view showing, as one example, a group of heads of a conventional ink jet color recording apparatus using inks different in density or consistency. 
     In this recording apparatus, a black (BK) ink head  311 BK, a first cyanogen (C 1 ) ink head  311 C 1 , a second cyanogen (C 2 ) ink head  311 C 2 , a first Magenta (M 1 ) ink head  311 M 1 , a second Magenta (M 2 ) ink head  311 M 2  and a yellow (Y) ink head  311 Y are arranged in parallel. 
     In the case of a head group having such a construction, since there is a need for the positional accuracy of adjacent nozzles of the heads to be set up on the order of microns, its manufacturing process becomes complicated, and additionally, installation of a head for each of ink colors leads to a relatively high head cost and makes difficult the size reduction of the head unit itself. Accordingly, the recording apparatus itself tends to increase in size and additionally to become costly. 
     In addition, since the plurality of heads are in a separated condition, there is a need to prepare, for each of the heads, an ink suction/pressurization receiving means for removing bubbles in the interiors of the nozzles or for recovering the ink from the increasing viscosity due to its being left for a long time. 
     One possible solution to these problems may be that a plurality of ink jet recording heads are formed integrally on the same substrate and disposed along the main scanning directions for conducting multivalued printing. 
     However, the point to be improved in the recording apparatus in which each of four color inks, namely, yellow, Magenta, cyanogen and block inks, existing in the main scanning directions has different densities is that four colors×two heads, namely, inks of eight colors., are necessary. 
     Meanwhile, it was found that yellow and block images are sufficiently expressible in color appearance through printing density or the like, and do not require variation of the ink density. On the other hand, the ink density has relatively great influence on color images based on Magenta and cyanogen in color appearance. Hence, a multivalued color recording apparatus using the needed minimum number of inks is desirable. 
     Accordingly, a recording apparatus can be designed such that one type is used as each of yellow and black inks and two types are taken as each of Magenta and cyanogen inks, that is, six color inks are put to use. 
     FIG. 12 is an illustration of one example in which nozzles for six colors are disposed separately in two heads. 
     In FIG. 12, a group of nozzles comprising a nozzle group  400 Y for ejecting an yellow ink, a nozzle group  400 M 1  for ejecting a first Magenta ink and a nozzle group  400 C 1  for ejecting a first cyanogen ink is formed in a recess section  357  made in a face  356  of an orifice plate  403  attached to a head  301 A. 
     In addition, a group of nozzles comprising a nozzle group  400 BK for ejecting a black ink, a nozzle group  400 M 2  for ejecting a second Magenta ink and a nozzle group  400 C 2  for ejecting a second cyanogen ink is formed in a recess section  357  made in a face  356  of an orifice plate  403  attached to a head  301 B. Still additionally, in the case of an apparatus employing different ink densities, since the dot formation order or time lag has influence when different inks are mixed to produce a secondary color, it is preferable that the different inks to be mixed are adjacent to each other in the main scanning directions of printing. 
     The disposition shown in FIG. 12, however, creates the following problems if two heads are disposed in the main scanning directions of printing. 
     That is, if the two heads are disposed in parallel as shown in FIG. 12, the yellow nozzle group and the black nozzle group assume an adjacent condition, and the two-color printing are required to be conduct simultaneously. 
     At this time, it was found that two types of inks interfere with each other on the record material to come to the boundary portion between images, that is, the so-called bleeding occurs, which degrades the print quality. Particularly, it can occur remarkably between yellow and black between which a great color difference exists. 
     Therefore, it is considered that nozzle groups discharging two different inks are disposed so as not to be adjacent to each other in the main scanning directions. That is, as shown in FIG. 13, a first nozzle of a nozzle group  200 M 1  of a head  301 A and a first nozzle of a nozzle group  200 M 2  thereof are placed on a line A—A. 
     However, in this case, a wasteful space  340  comes about in the head section so that the head itself increases in size to cause the size increase of the recording apparatus itself. 
     One possible solution to these problems would be that the wasteful space is removed from the head in FIG. 13 as disclosed in Japanese Unexamined Patent Publication No. (HEI) 7-132619. That is, as shown in FIG. 14, the head  301 A and the head  301 B are disposed and density-different inks are used to enable high-quality multivalued color recording, and additionally, the nozzles of adjacent nozzle groups are disposed in a state shifted substantially by ½ of a nozzle pitch from each other in directions different from the main scanning directions to double the resolution for formation of a color image with a high gradation. 
     Furthermore, as shown in FIG. 15, the employment of a head  391 B having a nozzle group holding only a black ink can accomplish higher-speed printing of a black image. Additionally, in this case, by using a B section of a nozzle group of a head  391  for ejecting a black ink, a nozzle group  490 Y of a head  391 A for ejecting an yellow ink, a nozzle group  490 M thereof for ejecting a Magenta ink and a nozzle group  490 C thereof for ejecting a cyanogen ink, a color image is also printable. 
     Secondly, a description will be given hereinbelow of an orifice plate  403  with nozzle groups in the aforesaid heads. 
     FIG. 16 is a perspective view showing a conventional orifice plate  403 , FIG. 17 is a cross-sectional view showing the orifice plate  403 , taken along a line B—B, and FIG. 18 is a cross-sectional view showing the orifice plate  403 , taken along a line E—E. 
     In a face  356  of the orifice plate  403 , there is made a recess section  357  which has a plurality of nozzles arranged therein. 
     The recess section  357  has a recessed configuration comprising a curved surface formed by a combination or connection of a first surface  351  and a second surface  352  at the deepest portion L′ of the recess section  357 , and further comprising a third surface  353  and a fourth surface  354  provided on both sides of this curved surface. 
     In comparison with the second surface  352 , the first surface  351  forms a curved surface having a relatively steep inclination, whereas, in comparison with the first surface  351 , the second surface  352  constitutes a gentler curved surface. Accordingly, the deepest portion L′ where the first surface  351  and the second surface  352  are combined is positioned above a nozzle  400 , that is, on the upstream side thereof in an arrow W direction indicative of a running direction of a blade  319  for wiping out an ink attached onto the recess section  357 . 
     Of heads manufactured so far, as shown in FIG. 17, there is a recording head using a member in which formed integrally are an orifice plate  403  having a number of common ink droplet discharging nozzles  400  and a top board  100  having groove portions forming ink passages corresponding respectively to the nozzles  400 . 
     In an ink jet recording apparatus employing such a recording head, there is a case that wet ink is attached onto the recess section  357  due to ink mist occurring when an ink is ejected from the recording head or due to satellite ink occurring at the refilling of the ink. Additionally, for example, when the ink is sucked from the nozzle  400  for restoration processing, the ink left at the suction can be attached to the recess section  357 . 
     Therefore, a restoring unit has been provided to remove such attached ink from an ejection surface. This restoring unit is principally made up of a suction device for discharging ink forcedly from the nozzle  400  and a wiping device for wiping and cleaning the recess section  357 . 
     For example, the wiping device is designed to make a blade  319 , made from an elastic material or the like and shown in FIG. 19, come directly into contact with the face  356  and the recess section  357  and to make the blade  319  move relatively to slide on or rub against the face  356  and the recess section  357 , thereby cleaning the plurality of nozzles  400  and the portions around them for securing the ejection stability. 
     However, it was found that a construction in which a head  301 A and a head  301 B are disposed in a state shifted from each other as shown in FIG. 19 can create a problem when the blade  319  wipes and cleans (wiping) the face  356  and the recess section  357 . 
     That is, since there is a need for the face of the orifice plate composed of a conventional top board with grooves to be as thin as possible in the vicinity of the nozzles but for the entire face to be thick sufficient to increase its strength, naturally, the entire face does not have a flat configuration but it has a recess portion. 
     In addition, in order to prevent the dries of the nozzles of the head, there is a need for the face to have a configuration to be covered with a cap installed commonly in a printer body; therefore, it is preferable that, in the face having the aforesaid recess portion, a part which comes into contact with the cap exists on the plane including a surface other than the recess portion. 
     In consequence, as shown in FIG. 17, the recess section  357  is formed at a substantially central portion of the entire face  356 . 
     Meanwhile, in recent years, with the increasing requirements of high image quality, high density and high resistance to light, the versatility of ink in kind has taken place, so that there has existed an increasing need to handle dispersive pigment based inks in addition to a conventional water soluble dye based inks. 
     If a pigment ink is used in a cartridge with a conventional configuration, when the residual ink on an orifice plate is wiped out by a blade, ink accumulation occurred in the vicinity of the third surface  353  and the fourth surface  354  of the recess section  357  as shown in FIG.  16 . 
     In general, the pigment-based ink has large molecules and has a fixedly attaching property. 
     For this reason, if some ink is yet left on the orifice plate after being wiped off, there is a possibility that the reception of the ink ejected becomes unstable. 
     In addition, the pigment ink left after wiped off can enter the nozzles due to the subsequent wiping operation by the blade, thereby causing an ejection-impossible condition. 
     Still additionally, in addition to the ink accumulation  500  shown in FIG. 16, the residual or leavings after the wiping can also occur slightly around the nozzles  400 , which can cause the deflection of ink ejected or the ejection-impossible condition. 
     A conventional means to solve this problem relates to the improvement of the wiping way using a blade placed in the printer body. Since the ink used so far has been an dye ink, this conventional means has worked successfully. However, when a pigment ink is used for a higher resistance to light and higher concentration, further improvement becomes necessary. 
     Moreover, in addition to the aforesaid problems arising with the recess section, the following problems will arise. 
     That is, when sliding on the face  356  and the recess section  357 , the blade  319  also slides simultaneously on a chip tank  302 A and a chip tank  302 B which have a flow passage for supplying the ink into a nozzle liquid chamber. The repetition of this operation can cause the ridgelines of the chip tanks  302 A and  302 B along the main scanning directions to damage the points A to D of the blade  319  as shown in FIG.  19 . If the wiping is done in this state, the point B of the blade  319  can induce the ink leavings on the head  301 A while the point C thereof can induce the ink leavings on the head  301 B; whereupon the nozzles  400  become a wet condition to lead to record contortion or ejection failure. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is a first object of the present invention to provide an ink jet recording head, an ink jet cartridge and an ink jet recording apparatus which can reduce the ink leavings or residual after wiping. 
     A second object of this invention is to provide an ink jet recording head, an ink jet cartridge and an ink jet recording apparatus which are capable of maintaining an excellent condition even if a pigment ink is put to use. 
     A third object of this invention is to provide an ink jet recording head, an ink jet cartridge and an ink jet recording apparatus which are capable of accomplishing less damages to a wiping blade. 
     For achieving these objects, in accordance with this invention, there is provided an ink jet recording head comprising a flat plate section having a recess section in its surface and an orifice plate having a plurality of openings made to eject a liquid and disposed linearly to be grouped in the recess section, with the surface of the flat plate section being cleaned by a cleaning member movable relative to the flat plate section in a direction perpendicular to a direction of the disposition of the ejecting openings in a state brought into contact with the surface of the flat plate section, wherein the recess section includes a combined curved surface made in a manner that a first curved surface having a first curvature and a second curved surface having a second curvature smaller than the first curvature are combined at a position corresponding to the deepest portion of the recess section so that the first curved surface is on the upstream side of the second curved surface in a cleaning direction of the cleaning member and made to extend in the disposition direction of the ejecting openings and further includes two inclined surfaces formed at both end portions of the combined curved surface to develop from the surface of the flat plate section in a state respectively separated from both end portions of the grouped ejecting openings existing in the vicinity of the deepest portion. 
     In an ink jet recording head thus constructed according to this invention, since the ejecting opening group is formed in the vicinity of the deepest portion of the recess section made in the orifice plate, the depth of the recess section assumes the minimum needed, thus making no sharp angle with respect to first and second inclined surfaces forming both end portions of the combined curved surface. Accordingly, the angles made at areas connecting the combined curved surface and the first and second inclined surfaces become blunt so that the liquid is hard to stay after the cleaning by the cleaning member. 
     It is also appropriate that the ejecting opening group is formed on the downstream side in the cleaning direction with respect to the deepest portion, that the surface in which the ejecting opening group is made is a general plane formed substantially perpendicularly to directions of liquid ejection by the ejecting openings, or that each of areas existing connectively between the first curved surface, the second curved surface, the two inclined surfaces and the general plane is formed as a smooth curved surface. 
     It is also possible that the ink jet recording head according to this invention includes an equipment body formed integrally with the orifice plate in a state where the surface of the flat plate section is used as one of component surfaces. 
     It is also possible that, in the equipment body, a radius of a curved surface formed on a first ridgeline portion defined by a surface, with which the cleaning member comes initially into contact with at the relative movement of the cleaning member, and the surface of the flat plate section to extend in a direction perpendicular substantially to the relatively moving direction of the cleaning member is below 0.1 mm, or that, in a second ridgeline portion defined by a surface including the recess section and a surface of the equipment body substantially perpendicular to the surface including recess section and substantially parallel with the relatively moving direction of the cleaning member, the radius of a curved surface formed on a portion on which the cleaning member slides at the relative movement is equal to or more than 0.2 mm. 
     Furthermore, it is also acceptable that the radius of a curved surface formed on a corner portion of the equipment body defined by the first and second ridgeline portions is equal to or more than 0.2 mm, that the starting position of the curved surface of the second ridgeline portion is separated by more than 0.1 mm from the ejecting opening closest to the second ridgeline portion, or that the liquid is a pigment ink. 
     Still furthermore, it is also appropriate that the ink jet recording head according to this invention is equipped with an electrothermal converter for generating thermal energy to be used for ink ejection, or that the ink jet recording head is of a type that an ink is ejected from the ejecting openings utilizing the film boiling occurring in the ink due to thermal energy from an electrothermal converter. 
     An ink jet cartridge according to this invention comprises the ink jet recording head according to this invention and a liquid container for holding an liquid to be supplied to the ink jet recording head. 
     An ink jet recording apparatus according to this invention comprises the ink jet cartridge according to this invention and a record medium conveying means for conveying a record medium onto which the liquid ejected from the ink jet recording head is adhered for recording. 
     In addition, the ink jet recording apparatus comprises the aforesaid ink jet recording apparatus according to this invention and a cleaning member moved relatively in a direction perpendicular to an arranging direction of ejecting openings while being brought into contact with a surface of a flat plate section of the ink jet recording head to clean the surface of the flat plate section. 
     According to this invention, since the ejecting opening group is formed in the vicinity of the deepest portion of the recess section made in the orifice plate, the depth of the recess section becomes at the minimum needed so that the angles made with respect to the first and second inclined surfaces forming both the end portions of the combined curved surface do not become sharp. Accordingly, the angles of the areas between the combined curved surface and the first and second inclined surfaces become blunt so that the liquid is hard to stay, and even if a pigment ink, easy to fix, is used, it is possible to maintain an excellent ink ejection condition for a long time. 
     Moreover, the first ridgeline portion, the second ridgeline portion and the corner portions of the equipment body formed integrally with the orifice plate are made to have a radius R, which enables less damage to the cleaning member and secures the certain cleaning of the recess section. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows schematically a construction of a color ink jet recording apparatus according to a first embodiment of the present invention; 
     FIG. 2 is an illustration useful for describing an ink jet recording head in the first embodiment of this invention; 
     FIG. 3 is an illustration for describing a wiping state in the first embodiment of this invention; 
     FIG. 4 is an illustration for explaining a head disposing position. 
     FIG. 5 is a perspective view for explaining a recess section made in a face of an orifice plate in the first embodiment of this invention; 
     FIG. 6 is a cross-sectional view taken along a line C—C in the orifice plate shown in FIG. 5; 
     FIG  7  is a cross-sectional view taken along a line D—D in the orifice plate shown in FIG. 5; 
     FIG. 8 is an illustration for describing a wiping state in a second embodiment of this invention; 
     FIG. 9 is an enlarged perspective view showing a head in the second embodiment of this invention; 
     FIG. 10 is an illustration for explaining a portion having a ridgeline portion radius R made on a chip tank and a starting position of the ridgeline portion with the radius R; 
     FIG. 11 is a perspective view showing a group of heads of a conventional; ink jet color recording apparatus; 
     FIG. 12 is an illustration of one example of conventional head disposing positions; 
     FIG. 13 is an illustration of one example of conventional head disposing positions; 
     FIG. 14 is an illustration of one example of conventional head disposing positions; 
     FIG. 15 is an illustration of one example of conventional head disposing positions; 
     FIG. 16 is a perspective view for describing a recess section made in a face of a conventional orifice plate; 
     FIG. 17 is a cross-sectional view taken along a line B—B in the orifice plate shown in FIG. 16; 
     FIG. 18 is a cross-sectional view taken along a line B—B in the orifice plate shown in FIG. 16; and 
     FIG. 19 is an illustration for describing a conventional wiping state. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Embodiments of the present invention will be described hereinbelow with reference to the drawings. 
     (First Embodiment) 
     FIG. 1 shows schematically a construction of a color ink jet recording apparatus according to a first embodiment of the present invention. 
     A recording apparatus, designated generally at reference numeral  100 , is composed of a carriage  102  carrying two heads  101 A and  101 B and further detachably holding ink tanks  110 A and  110 B for supplying inks to the heads  101 A and  101 A, guide shafts  104  and  104  serving as a guide for the reciprocation of the carriage  102 , a paper-feeding roller  107  for feeding record paper  106 , a paper conveying roller  108  for conveying the record paper  106 , and a blade  111  forming a component of a wiping device for restoring the printing functions of the heads  101 A and  101 B. 
     Secondly, a description will be given hereinbelow of the printing onto the record paper  106  by the recording apparatus  100 . 
     Upon receipt of a print signal from a non-shown host computer, the record paper  106  is fed by the paper conveying roller  108  and the paper feeding roller  107  to be set at a printing position. Subsequently, the heads  101 A and  101 B are released from a non-shown cap, and the carriage  102  carrying the heads  101 A and  101 B are moved to reciprocate along the guide shaft  104  and the guide shaft  105  to conduct a printing operation on the record paper  106 . 
     In the head  101 A, a plurality of ejecting openings for discharging three kinds of inks, namely, a yellow ink, a first Magenta (M 1 ) ink and a first cyanogen (C 1 ) ink, supplied from the ink tank  110 A are disposed linearly to form nozzle groups  200 Y,  200 M 1  and  200 C 1  (see FIG.  2 ). Likewise, in the head  101 B, a plurality of ejecting openings for discharging a black (BK) ink, a second Magenta (M 2 ) ink and a second cyanogen (C 2 ) ink supplied from the ink tank  110 B are disposed linearly to form nozzle groups  200 BK,  200 M 2  and  200 C 2  (see FIG.  2 ). 
     For the first Magenta and the second Magenta or the first cyanogen and the second cyanogen, a variable-density ink or different kinds of dyes can be put to use. 
     In addition, although the heads  101 A and  101 B arranged have the same construction, it is also acceptable to use different kinds of heads, for instance, different in nozzle diameter. 
     The construction of the heads  101 A and  101 B will be described in detail later. 
     The ink tanks  110 A and  110 B are for storing the aforesaid color inks, and three kinds of inks are put in each of the ink tanks  110 A and  110 B. When pushed into insertion openings separately provided in the cartridge  103 , the ink tanks  110 A and  110 B are coupled to rubber seal portions (not shown) placed thereunder and further to stainless pipes or the like set in the heads  101 A and  101 B, respectively, so that the respective inks are supplied from the ink tanks  110 A and  110 B to the corresponding nozzles. 
     When the heads  101 A and  101 B are released from the non-shown cap or capped therewith, the blade  111  is moved to slide on or rub against the ink ejecting surfaces of the heads  101 A and  101 B, thereby removing (wiping off) the residual ink on the ejecting surfaces. 
     Furthermore, referring to FIG. 2, a description will be given hereinbelow of the heads  101 A and  101 B forming an ink jet recording head according to a first embodiment of this invention. 
     In the construction of each of the heads  101 A and  101 B, a chip tank  204  having an orifice plate  203  and a printed circuit board (PCB)  202  having a connector section  202   a  are fitted onto an aluminium-made base plate  201 . 
     In a recess section  157  made in a face  156  of the orifice plate  203  attached to the head  101 A, there are linearly formed a nozzle group  200 Y for discharging an yellow ink, a nozzle group  200 M 1  for ejecting a first Magenta ink and a nozzle group  200 C 1  for ejecting a first cyanogen ink. 
     Likewise, in a recess section  157  made in a face  156  of the orifice plate  203  attached to the head  101 B, there are linearly formed a nozzle group  200 M 2  for ejecting a second Magenta ink, a nozzle group  200 C 2  for ejecting a second cyanogen ink and a nozzle group  200 BK for ejecting a black ink. Each of nozzle group is made by disposing 48 nozzles linearly, and the respective nozzle groups are arranged at an interval more than the nozzle pitch. 
     For each of the nozzle groups, a non-shown ink passage is formed to supply each color ink, and for each of the nozzles, a non-shown electrothermal converter is provided to eject ink droplets. In accordance with the input of a print signal from a non-shown print signal generating means, the electrothermal converter is heated to foam the ink so that the discharge of the ink droplets from each of the nozzles is controlled by that foaming force. 
     In this construction, two heads  101 A and  101 B are placed and, for each of yellow and black, one kind of ink is used while, for each of Magenta and cyanogen, two kinds of inks are employed. This construction can offer sufficient gradation, and for the following reason. 
     It is well known that, if a variable-density ink is used for yellow and black, the gradation further improves. In the case in which each of inks is used singly, the consistency is changeable according to the printing density. However, in the case of cyanogen and Magenta, its color tone has great influence on the saturation and the actual appearance differs. That is, in this embodiment, on the inks affected greatly by the color tome of the color print, consistency variation is taken for achieving high gradation. 
     The heads  101 A and  101 B are arranged in a state shifted from each other in a direction different from the main scanning direction for printing so as to form a step, with the step being established by shifting the heads  101 A and  101 B by a distance corresponding to the width of the nozzle group for one color plus the separation for partition between the nozzle groups in the direction different from the main scanning direction (see FIG.  4 ). 
     The printed circuit board  202  is connected through its connector section  202   a  to a body side connector for receiving a power supply for the drive of the heads  101 A and  101 B for the ink ejection, a print signal and others. 
     FIG. 3 shows a state of wiping the heads  101 A and  101 B. 
     The relative movement of the blade  111  with respect to the heads  101 A and  101 B accomplishes the wiping in a direction indicated by an arrow W. 
     FIG. 4 is an illustration useful for explaining a disposing position of the heads  101 A and  101 B. 
     The adjacent nozzles in the main scanning direction of the arrow W are arranged at positions along a line A—A, that is, they are disposed so that the first nozzle of the nozzle group  200 M 1  of the head  101 A and the first nozzle of the nozzle group  200 M 2  of the head  101 B coincide or are aligned with each other. 
     Still furthermore, a description will be given hereinbelow of the recess section  157  made in the face  156  of each of the heads  101 A and  101 B. 
     In this embodiment, the recess sections  157  of the heads  101 A and  101 B have the same configuration, and the description will be made representatively of only the head  101 A. 
     FIG. 5 is a perspective view showing the recess section  157  made in the face  156  of the orifice plate  203 , FIG. 6 is a cross-sectional view showing the orifice plate  203 , taken along a line C—C of FIG. 5, and FIG. 7 is a cross-sectional view of the orifice plate  203 , taken along a line D—D of FIG.  5 . In FIG. 6, reference character H represents a position of the location of an electrothermal converter which generates thermal energy to be used for the ink ejection. 
     The recess section  157  has a concave configuration comprising a curved surface made by combining or coupling a first surface  151  and a second surface  152  at the deepest portion M of the recess section  157  as shown in FIG. 6, and further comprising third surface  153  and a fourth surface  154  formed both sides of this curved surface. 
     As compared with the second surface  152 , the first surface  151  is formed as a curved surface having a gentler or slower curve, while, as compared with the first surface  151 , the second surface  152  is formed as a curved surface having a relatively steep or high inclination. Accordingly, the deepest portion M at which the first surface  1512  and the second surface  152  are combined with each other is located under a central portion  158  of the recess section  157  made in the face  156 , that is, on the downstream side of the central portion  158  in the arrow W indicative of the advancing direction of the blade  111 . 
     Furthermore, by forming the curved surface configuration including the first surface  151  and the second surface  152  so that the deepest portion M is in the vicinity of the nozzles  200 , a more optimal recess section  157  is attainable. 
     Still furthermore, a flat fifth surface can also be formed at a portion of the connection of the first surface  151  and the second surface  152  to limit the angle of the recess section  157  with respect to the nozzles  200 , which can more preferably secure the stabilization of the ejection of the ink. 
     Yet furthermore, it is more desirable that a curved surface is formed at the connection between the first surface  151 , the second surface  152 , the third surface  153 , the fourth surface  154  and the fifth surface so as to prevent the occurrence of distinct bending points. 
     The above-described construction can improve the configuration of the recess section  157  in depth, and can solve the two problems causing ink to be left after wiping, that is, the position of the deepest portion deeper than the nozzles  200  exists on the upstream side of the positions of the nozzles  200  in the blade advancing direction and the outcome is that the inclinations of both the sides (the conventional third surface  353  and the conventional fourth surface  354  in FIG. 16) of the recess section  157  become steep. 
     Thus, it is possible to eliminate the problems on the ink leavings after wiping (ink accumulation  500  in FIG. 16) which will occur in the case of the use of a pigment ink, which allows the use of a pigment ink for high consistency, high resistance to light and high image quality, so that the quality of an image to be recorded on a record material is improvable. 
     In addition, the recess section  157  in this embodiment can offer the following effects. 
     In the case in which the two heads  101 A and  101 B are disposed in a state shifted from each other as shown in FIG. 4, if the recess section has a configuration equal or similar to that of the conventional recess section  357  in FIG. 17, in wiping by the blade  111 , as compared with a single-cartridge construction, the advance and inclination of the blade  111  with respect to the recess section  357  are required to be set with higher precision. 
     One reason is that, in the case of the head construction in FIG. 3 in which the nozzle groups for ejecting two different inks are disposed without being adjacent to each other in the main scanning direction, when the residual ink on the orifice plate  203  is wiped off by the blade  111 , the blade  111  vibrates after the wiping of the head  101 A so that irregular wiping can come about at the wiping of the head  101 B to cause the ink leavings even after the wiping. 
     On the other hand, the recess section  157  in this embodiment improves the wiping ability of the blade  111  to the recess section  157 , so that the margin on the advance and inclination of the blade  111  with respect to the recess section  157  increases considerably and the irregular wiping is eliminable, which permits the use in a high-speed high-image-quality printer. 
     As described above, the recess section in this embodiment, having the foregoing configuration, accomplishes less ink residual after wiping and permits the head to employ a pigment ink. 
     (Second Embodiment) 
     FIG. 8 shows wiping states of heads  601 A and  601 B in a second embodiment of this invention, and FIG. 9 is an enlarged perspective illustration of an appearance of a chip tank  602  of the head  601 A shown in FIG.  8 . 
     The heads  601 A and  601 B basically have the same construction as that of the head  101 A or  101 B in the first embodiment shown in FIG. 2, and the detailed description thereof will be omitted for brevity. 
     As FIG. 8 shows, in wiping, a portion between points A and C of a blade  711  is first brought into contact with a front edge portion  604  forming a first ridgeline portion of a chip tank  602  of the head  601 A and points A and C thereof are immediately brought into contact with front edge end portions  605  forming corner portions existing at both end portions of the front edge portion  604 , respectively. Following this, the portion between the points A and C of the blade  711  wipes off the ink on a face  656  and a recess section  657  while the points A and C of the blade  711  slides a ridgeline  603  forming a second ridgeline portion. Subsequently, likewise, in the blade  711 , the point B instead of the point A and the point D in place of the point C are brought into contact with a front edge portion  604  forming a first ridgeline portion of a chip tank  602  of the head  601 B to wipe off the ink on a face  656  and a recess section  657  while the blade  711  slides on a ridgeline  603  forming a second ridgeline portion, then terminating the wiping operation. 
     In the chip tanks  602 A and  602 B, the front edge portions  604 , the front edge end portions  605  and the ridgelines  603  are formed to have a curved surface or roundness whose radius is R, thereby presenting a smooth configuration. 
     Incidentally, the recess section of each of the heads  601 A and  601 B can also be identical to that in the above-described first embodiment. 
     In addition, for the purpose of use in common, it is also appropriate that the chip tanks  602  of the head  601 A and the head  601 B have the same configuration. 
     Still additionally, because the width of the blade  711  is determined to wipe the recess section  657  holding the orifice nozzles, there is no need for the width to be larger than the length between the points A and D as shown in FIG. 8, and it is also possible that the width is larger than the length between the points B and C but smaller than the length between the points A and C. In this case, the ridgeline curved surface of the radius R to be formed on the front edge end portions  605  and the ridgelines  603  can be limited to only those with which the points B and C of the blade  711  come into contact. 
     As described above, according to this embodiment, the hip tanks  602  are constructed such that a ridgeline curved surface whose radius is R is formed on the portions with or on which the blade  711  comes into contact or slides, that is, the front edge portions  604 , the front edge end portions  605  and the ridgelines  603 , which prevents the damages to the blade  711 . 
     Moreover, a description will be given hereinbelow of first to fourth study examples in the above-described embodiments. 
     The first to third study examples relate to a study about damages to the blade  711  and the record contortion and ejection failure which occurred in the actual printing when the radius R of the front edge end portions  603  and the ridgeline portion  603  was changed, while the fourth example relates to a study about these problems in the case in which the starting position of the ridgeline curved surface of the radius R on the ridgelines  603  was changed. 
     In the first study example, the ridgeline radiuses R of the front portion  604 , front edge end portions  605  and ridgelines  603  of the chip tank  602  was set to R=0.05 mm, R=0.3 mm and R=0.03, respectively, and the wiping operation was repeated two hundred thousands times. 
     In consequence, the points A and B of the blade  711  was damaged or cut by the ridgeline  603  shown in FIG.  8 . In this case, the guaranteed printing quantity of the main body was approximately fifty thousands, and the number of times of wiping was approximately two hundred thousands. 
     When the wiping was done in a state where the points A and B were damaged, the point A caused the ink residual on the head  601 B while the point B caused the ink residual on the head  601 A, so that the ejecting openings were wet to cause the record contortion and ejection failure. 
     Only the value of the radius R of the ridgeline  603  of the chip tank  602  was changed and the wiping operation was repeated two hundred thousands times. In this case, the examination results on the damages to the blade  711  and the record contortion and ejection failure in the actual printing are shown in Table 1. 
     
       
         
               
               
               
               
               
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
             
             
               
                   
                 R[mm] 
                 0.03 
                 0.1 
                 0.2 
                 0.3 
                 0.4 
                 0.5 
               
               
                   
                 Print Result 
                 x 
                 x 
                 ∘ 
                 ∘ 
                 ∘ 
                 ∘ 
               
               
                   
                   
               
             
          
         
       
     
     Thus, when the ridgeline  603  assumes R=0.2 mm or more as a minimum, we can consider that the blade  711  is subjected to less damage so that the record contortion or ejection failure does not occur easily. 
     In the second study example, the ridgeline radiuses R of the front portion  604 , front edge end portions  605  and ridgelines  603  of the chip tank  602  was set to R=0.05 mm, R=0.03 mm and R=0.5 mm, respectively, and the wiping operation was conducted in this condition. 
     In consequence, the point A caused the ink residual on the head  601 B after wiping, while the point B caused the ink residual on the head  601 A after wiping; whereupon, the ejecting openings were wet and the record contortion or the ejection failure occurred. 
     Table 2 shows the examination results on the damage to the blade  711  and the record contortion and the ejection failure in the actual printing in the case in which the value of the ridgeline curved surface radius R of the front edge end portion  605  was changed and the wiping operation was repeated two hundred thousands times. 
     
       
         
               
               
               
               
               
               
               
               
             
           
               
                   
                 TABLE 2 
               
               
                   
                   
               
             
             
               
                   
                 R[mm] 
                 0.03 
                 0.1 
                 0.2 
                 0.3 
                 0.4 
                 0.5 
               
               
                   
                 Print Result 
                 x 
                 x 
                 ∘ 
                 ∘ 
                 ∘ 
                 ∘ 
               
               
                   
                   
               
             
          
         
       
     
     Thus, when the front edge end portion  605  assumes at least R=0.2 mm or more, we can consider that the blade  711  is subjected to less damage so that the record contortion or ejection failure does not occur easily. 
     In the third study example, the ridgeline radiuses R of the front portion  604 , front edge end portions  605  and ridgelines  603  was set to R=0.3 mm, R=0.3 mm and R=0.5 mm, respectively, and the wiping operation was conducted in this condition. 
     In consequence, after the wiping of the ejecting opening surface, dust and viscosity-increasing ink attached onto the blade  711  sliding surface could not be removed at the chip tank end portions, and when the wiping was conducted in this state, the dust and the viscosity-increasing ink entered the ejecting openings or adhered to the periphery of the ejecting openings, thereby further caused the record contortion or the ejection failure. 
     Table 3 shows the examination results about the record contortion and the ejection failure in the actual printing when the value of the ridgeline curved surface radius R of the front edge portion  604  was changed and the wiping operation was conducted in this radius R changing condition. 
     
       
         
               
               
               
               
               
               
               
               
             
           
               
                   
                 TABLE 3 
               
               
                   
                   
               
             
             
               
                   
                 R[mm] 
                 0.03 
                 0.05 
                 0.1 
                 0.2 
                 0.3 
                 0.4 
               
               
                   
                 Print Result 
                 ∘ 
                 ∘ 
                 ∘ 
                 x 
                 x 
                 x 
               
               
                   
                   
               
             
          
         
       
     
     Thus, if the ridgeline radius R of the front edge portion  604  is below at least R=0.05, it is considered that the dust and the viscosity-increasing ink attached onto the blade  711  sliding surface can be wiped off at the aforesaid chip tank end portions, so that the record contortion and the ejection failure are hard to occur. 
     In the fourth study example, the ridgeline radiuses R of the front portion  604 , front edge end portions  605  and ridgelines  603  was set to R=0.05 mm, R=0.3 mm and R=0.5 mm, respectively, and the ridgeline radius R of the ridgeline  603  was started from a position separated by L 1 =0.03 mm from the end portion of the nozzle group as shown in FIG.  10 . 
     In consequence, a suction device for discharging an ink forcedly from the ejecting openings could not accomplish the suction because of no complete sealing so that difficulty was encountered in removing the ink attached onto the ejecting opening surface. When the wiping was further conducted in this state, the dust (paper fuzz and others) or the viscosity-increasing ink (ink after volatile components are evaporated) entered the ejecting openings or adhered to the periphery of the ejecting openings, which caused further record contortion and ejection failure. 
     Table 4 shows the examination results about the record contortion and the ejection failure in the actual printing in the case in which the starting position of the curved surface, whose radius is R, with respect to the end portion of the nozzle group was changed and the wiping operation was conducted in this starting position changing state. 
     
       
         
               
               
               
               
               
               
               
               
             
           
               
                   
                 TABLE 4 
               
               
                   
                   
               
             
             
               
                   
                 L1[mm] 
                 0.03 
                 0.05 
                 0.1 
                 0.2 
                 0.3 
                 0.4 
               
               
                   
                 Print Result 
                 x 
                 x 
                 ∘ 
                 ∘ 
                 ∘ 
                 ∘ 
               
               
                   
                   
               
             
          
         
       
     
     Thus, if the starting position of the curved surface of the radius R on the ridgeline  603  is set to a position separated by at least 0.1 mm or more from the end portion of the nozzle group, it is considered that the suction device can be sealed hermetically to secure sufficient suction so that the record contortion and the ejection failure are hard to occur. 
     As described above, if the radius R of the curved surface of the ridgelines  603  is set to be more than R=0.2 mm, the radius R of the front edge end portions  605  is set to be more than R=0.2 mm and the radius R of the front edge portion  604  is set to be less than R=0.05 mm, the damage to the blade  711  is substantially preventable so that it is possible to surely clean the portions around the ejecting openings by the wiping. 
     In addition, if the starting position of the curved surface of the radius R on the ridgelines  603  is set at a position separated by at least more than 0.1 mm from the end portion of the nozzle group, it is possible to certainly clean the portions around the ejecting openings by the suction device. 
     Accordingly, less occurrence of the record contortion and the ejection failure becomes possible.