Abstract:
A printing apparatus to form an image on a recording medium is provided. The printing apparatus includes a first recording head, which is movable in a main scanning direction and ejects a specific-colored ink onto the recording medium, a first ink cartridge to store the specific-colored ink, a first ink conveyer, which connects the first recording head and the first ink cartridge to convey the specific-colored ink, and a first conveyer retainer, which is movable along with the first recording head and holds the first ink conveyer to extend there-along. The first conveyer retainer is arranged in a position higher than a connecting portion of the first ink conveyer with the first recording head and holds the first ink conveyer in a vertical range between a top level of the first conveyer retainer and a bottom level of the first ink cartridge.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims priority from Japanese Patent Application No. 2008-093059, filed on Mar. 31, 2008, the entire subject matter of which is incorporated herein by reference. 
     BACKGROUND 
     1. Technical Field 
     An aspect of the present invention relates to a printing apparatus, specifically to a printing apparatus having a print head for ejecting white ink, an ink supplying system for the white ink, and an ink supplying system retainer. 
     2. Related Art 
     Conventionally, an inkjet printer to form an image in colors has been suggested. One example of such an inkjet printer is disclosed in Japanese Patent Provisional Publication No. 2005-199506. According to the above publication, the inkjet printer is configured such that the tubes to supply colored inks from ink cartridges to the inkjet heads are supported by retainer members, which are mounted on carriages to drive the inkjet heads, and guided by guiding members, which are located rear sides of the carriages. According to this configuration, postures of the tubes extending from the guide members to the inkjet heads are maintained to be substantially steady so that pressure to the inks in the tubes can be less fluctuated. Additionally, with the ink cartridges being fixed to the body of the inkjet printer, the carriages can be driven in smaller space in the inkjet printer to carry the inkjet heads. 
     In the above inkjet printer, however, the retainer members are arranged in positions higher than the carriages; therefore, level differences between portions of the tubes being held by the retainer members and connecting positions of the inkjet heads and the tubes and between the portions of the tubes being held by the retainer members and portions of the tubes at the guide members can be large. 
     SUMMARY 
     It is to be noted that CMYK (cyan, magenta, yellow, and black) colored inks can be used without difficulties over such level differences. However, W (white) ink, containing oxidized titanium and therefore having higher density of colorant with respect to densities of colorants in the other colored inks, and a particle size thereof being larger, can easily settle out in the tubes. 
     Accordingly, the densities of the white ink may vary within the tube, and troubles such as irregular ejection of the ink from the inkjet head, insufficient flow of the ink flow to the inkjet head, or uneven densities of the color in a formed image can be caused due to the uneven distribution of the ink within the tube. 
     In view of the above drawbacks, the present invention is advantageous in that a printing apparatus, in which unevenness of the white ink in the tube can be reduced and concentration gradient of the white ink within the tube can be smaller, is provided. 
     According to an aspect of the present invention, a printing apparatus to form an image on a recording medium, including a first recording head, which is movable in a main scanning direction of the printing apparatus and ejects a specific-colored ink onto the recording medium, a first ink cartridge to store the specific-colored ink, a first ink conveyer, which connects the first recording head and the first ink cartridge to convey the specific-colored ink from the first ink cartridge to the first recording head, and a first conveyer retainer, which is movable along with the first recording head and holds the first ink conveyer to extend there-along is provided. The first conveyer retainer is arranged in a position higher than a connecting portion of the first ink conveyer with the first recording head and holds the first ink conveyer in a vertical range between a top level of the first conveyer retainer and a bottom level of the first ink cartridge. 
     According to the above configuration, entire height of the first ink conveyer can be minimized, and the first ink conveyer can be maintained in a horizontally close range. Therefore, concentration gradient of the specific-colored ink within the first ink conveyer can be smaller. 
    
    
     
       BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS 
         FIG. 1  is a plane view of an inkjet printer according to an embodiment of the present invention. 
         FIG. 2  is a front view of the inkjet printer according to the embodiment of the present invention. 
         FIG. 3  is a side view of the inkjet printer according to the embodiment of the present invention. 
         FIG. 4  is a block diagram to illustrate an electrical configuration of the inkjet printer according to the embodiment of the present invention. 
         FIGS. 5A-5E  are schematic top views of the inkjet printer to illustrate movements of an ink supplier holder in the inkjet printer  1  according to the embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, an embodiment according to an aspect of the present invention will be described with reference to the accompanying drawings.  FIG. 1  is a plane view of an inkjet printer  1  according to the embodiment of the present invention.  FIG. 2  is a front view of the inkjet printer  1  according to the embodiment of the present invention.  FIG. 3  is a side view of the inkjet printer  1  according to the embodiment of the present invention.  FIG. 4  is a block diagram to illustrate an electrical configuration of the inkjet printer  1  according to the embodiment of the present invention.  FIGS. 5A-5E  are schematic top views of the inkjet printer  1  to illustrate movements of an ink supplier holder in the inkjet printer  1  according to the embodiment of the present invention. 
     The inkjet printer  1  in the present embodiment is configured to be a known inkjet printer having first inkjet heads  21  and second inkjet heads  22  to form an image on a recording medium in inks ejected from nozzle surfaces of the first and the second inkjet heads  21 ,  22  according to image data. In the inkjet printer  1 , a piece of fabric can be used as a recording medium, and the piece of fabric may be, for example, a T-shirt. As shown in  FIGS. 1 and 2 , the inkjet printer  1  is provided with a flat base plate  2  at a bottom and a chassis  10  to cover the entire body of the inkjet printer  1 . 
     The first inkjet heads  21  are mounted on a carriage  13 , which is reciprocated in a right-and-left direction in  FIG. 1  along a guide rail  11 . In the vicinity of a right-hand end of the guide rail  11 , a first carriage motor  24  ( FIG. 4 ) to carry the first inkjet heads  21  is provided. Further, a pulley (not shown) is provided in the vicinity of a left-hand end of the guide rail  11 , and a carriage belt (not shown) is drawn between the first carriage motor  24  and the pulley. The carriage belt is fixed to the carriage  13  so that the carriage  13  is reciprocated along the guide rail  11  in the right-and-left direction (i.e., the main scanning direction) when the first carriage motor  24  is activated. At one of the right-hand end and the left-hand end of the reciprocative range of the carriage  13 , a maintenance mechanism (not shown) such as a capping unit and a purge unit for the first inkjet heads  21  is provided. 
     On the right-hand end of the chassis  10 , first ink cartridges  31  containing white ink therein are detachably attached. The first ink cartridges  31  are connected to each of the inkjet heads  21  by flexible ink conveyer tubes  34  so that the inks stored in the first ink cartridges  31  are conveyed to each channel of the inkjet heads  21 . According to the present embodiment, all of the inkjet heads  21  are provided to discharge white ink therefrom, and the first ink cartridges  31  respectively contain white ink. 
     The ink conveyer tubes  34  to supply the ink to the first inkjet heads  21  are moved along with first inkjet heads  21  when the carriage  13  with the first inkjet heads  21  is reciprocated in the main scanning direction. Therefore, the ink conveyer tubes  34  are formed to be longer than a length of the guide rail  11 . The ink conveyer tubes  34  with the length are held by a first arm  36  to extend there-along so that the ink conveyer tubes  34  can smoothly move to follow the carriage  13 . 
     The first arm  36  includes a rear portion, which is a thin and elongated plate rotatable about a supporting point  36   a , and a supporting point  36   b  is provided at an end of the rear portion. The first arm  36  further includes a front portion, which is a thin and elongated plate rotatable about the supporting point  36   b  and is coupled to the carriage  13  at a supporting point  36   c . Movements of the first arm  36  will be described hereinbelow with reference to  FIGS. 5A-5E . 
     When the carriage  13  is at the left end on the guide rail  11 , as shown in  FIG. 5A , an interior angle between the rear portion and the front portion of the first arm  36  is an acute angle. As the carriage  13  is driven toward the left-hand side of the inkjet printer  1  in a direction indicated by an upper arrow (i.e., toward the upper side in  FIG. 5B ), the front portion and the rear portion of the first arm  36  are rotated about the supporting point  36   b  and the supporting point  36   a  respectively, and the interior angle between the front portion and the rear portion transits to be widened. When the carriage  13  is moved to the left-hand end (i.e., the upper end in  FIG. 5C ), the interior angle between the front portion and the rear portion of the first arm  36  becomes an obtuse angle. Thereafter, when the carriage  13  makes a turn at the left-hand end of the guide rail  11  and returns in a direction indicated by downward arrows in  FIGS. 5D and 5E  (i.e., toward the lower side), the interior angle between the front portion and the rear portion of the first arm  36  becomes acute once again as shown in  FIG. 5E . As shown in  FIGS. 1 and 2 , the ink conveyer tubes  34  are bound up to the first arm  36  at portions corresponding to the front portion and the rear portion respectively. Therefore, throughout these movements shown in  FIGS. 5A-5E , horizontal levels of the front portion and the rear portion of the first arm  36  are maintained substantially steady in a same horizontal plane. Features of arrangement of the first arm  36  and the ink conveyer tubes  34  will be described later in detail. 
     The inkjet printer  1  according to the embodiment is equipped with a guide rail  12  ( FIG. 1 ), which is arranged in parallel with the guide rail  11 , to guide a carriage  14  with a second inkjet head  22  being mounted. As shown in  FIG. 2 , the guide rail  12  is arranged in a position higher than the guide rail  11 . 
     In the vicinity of a left-hand end of the guide rail  12 , a second carriage motor  25  ( FIG. 4 ) to carry the second inkjet heads  22  is provided. Further, a pulley (not shown) is provided in the vicinity of the right-hand end of the guide rail  12 , and a carriage belt (not shown) is drawn between the second carriage motor  25  and the pulley. The carriage belt is fixed to the carriage  14  so that the carriage  14  is reciprocated along the guide rail  12  in the left-and-right direction (i.e., the main scanning direction) when the second carriage motor  25  is activated. At one of the right-hand end and the left-hand end of the reciprocative range of the carriage  14 , a maintenance mechanism (not shown) such as a capping unit and a purge unit for the second inkjet heads  22  is provided. 
     On the left-hand end of the chassis  10 , second ink cartridges  32  containing CMYK inks respectively therein are detachably attached. The second ink cartridges  32  are connected to each of the inkjet heads  22  by flexible ink conveyer tubes  35  so that the inks stored in the second ink cartridges  32  are conveyed to each channel of the inkjet heads  22 . 
     The ink conveyer tubes  35  to supply the ink to the second inkjet heads  22  are moved along with second inkjet heads  22  when the carriage  14  with the second inkjet heads  22  is reciprocated in the main scanning direction. Therefore, the ink conveyer tubes  35  are formed to be longer than a length of the guide rail  12 . The ink conveyer tubes  35  with the length are held by a second arm  37  to extend there-along so that the ink conveyer tubes  35  can smoothly move to follow the carriage  14 . 
     The second arm  37  includes a rear portion, which is a thin and elongated plate, rotatable about a supporting point  37   a , and a supporting point  37   b  is provided at an end of the rear portion. The second arm  37  further includes a front portion, which is a thin and elongated plate, rotatable about the supporting point  37   b  and is coupled to the carriage  14  at a supporting point  37   c . Movements of the second arm  37  with the ink conveyer tubes  35  are, as shown in  FIGS. 5A-5E , similar but only bilaterally symmetrical to the movements of the first arm  36  with the ink conveyer tubes  36  as described above. Therefore, description of the movements of the second arm  37  with the ink conveyer tubes  35  are omitted herein. 
     As shown in  FIGS. 1 and 2 , the ink conveyer tubes  35  are bound up to the second arm  37  at portions corresponding to the front portion and the rear portion respectively. Therefore, throughout the movements shown in  FIGS. 5A-5E , horizontal levels of the front portion and the rear portion of the second arm  37  are maintained substantially steady in a same horizontal plane. 
     It is to be noted that the guide rail  12  is arranged in the position vertically higher than the guide rail  11 ; therefore, movements of the first arm  36  and the second arm  37  as shown in  FIGS. 5A-5E  do not interfere each other even when the second arm  37  moves to cross over the first arm  36 . 
     The inkjet printer  1  is equipped with a platen  5 . The platen  5  is formed to have a substantially rectangular-shaped plate, on which the recording medium (e.g., a T-shirt) is placed in a printable posture in the inkjet printer  1 . The platen  5  is supported by a platen feed unit  7 , which includes a guide rail (not shown) and a platen feed motor  40  ( FIG. 4 ) being a stepping motor arranged at a rear end portion (i.e., upper end in  FIG. 1 ) of the guide rail. When the platen feed motor  40  is activated, the platen  5  is reciprocated along the guide rail in the front- and-rear direction (i.e., up-and-down direction) in  FIG. 1 . The inkjet printer  1  may have a plurality of sizes of platen  5 , which can be selected according to, for example, sizes and shapes of the recording media. 
     At right-hand front of the inkjet printer  1  is provided an operation panel  28 , through which a user inputs an instruction for the inkjet printer  1 . The operation panel  28  includes print buttons  29  and a display  30 . 
     Next, referring to  FIG. 4 , an electrical configuration of the inkjet printer  1  will be described.  FIG. 4  is a block diagram showing the electrical configuration of the inkjet printer  1  according to the present embodiment of the invention. As shown in  FIG. 4 , the inkjet printer  1  is provided with a control unit  100 , and the control unit  100  includes a CPU  110  that controls the entire operation in the inkjet printer  1 . The CPU  110  is connected with a ROM  120 , a RAM  130  through a bus  115 . The ROM  120  stores various controlling programs to be executed in the CPU  110 . The RAM  130  temporarily stores data concerning the operations in the inkjet printer  1 . 
     A print control unit  140  includes a head controller  139 , which drives piezoelectric actuators for each of the channels in the first inkjet heads  21  and the second inkjet heads  22 . The print control unit  140  further includes a first head drive controller  141  to activate the first carriage motor  24 , a second head drive controller  142  to activate the second carriage motor  25 , and a platen feed motor controller  143  to activate the platen feed motor  40 . 
     The print control unit  140  further includes a sensor input unit  144 , which receives input signals provided from a print start key  29   a , a cancel key  29   b , and a maintenance key  29   c . The print start key  29   a , the cancel key  29   b , and the maintenance key  29   c  are provided on the operation panel  28 . The operation panel  28  further includes a data reception indicator  30   a , an error indicator  30   b , and the display  30 , which are controlled by a display control unit  145 . 
     The inkjet printer  1  in the present embedment includes a first maintenance mechanism and a second maintenance mechanism respectively on either (right or left) side of the guide rail  11  and the guide rail  12 . The first and the second maintenance mechanisms serve to maintain operating conditions of the first inkjet heads  21  and the second inkjet heads  22  respectively. The first maintenance mechanism includes a first maintenance motor  41 , and the second maintenance mechanism includes a second maintenance motor  42 . The print control unit  140  is provided with a first maintenance controller  146  to activate the first maintenance motor  41  and a second maintenance controller  147  to activate the second maintenance motor  42 . 
     Next, arrangement of the ink conveyer tubes  34  to supply white ink to the first inkjet heads  21  according to the embodiment of the present invention will be described. The inkjet printer  1  in the present embodiment is equipped with the first inkjet heads  21  to eject white ink and the second inkjet heads  22  to eject CMYK colored inks. As has been described above, the white ink contains oxidized titanium and has higher density of pigment with respect to densities of pigments in the other colored inks; therefore, a particle size of the white ink is larger. In consideration of these features of the white ink, the inkjet printer  1  is configured such that the vertical level of the ink conveyer tubes  34  for the white ink is substantially constant to be in a horizontal plane throughout the length between the first cartridges  31  and the first inkjet heads  21 . 
     More specifically, as shown in  FIG. 3 , segments of the ink conveyer tubes  34  between a bound portion A, in which the ink conveyer tubes  34  are bound to the first arm  36 , and a connected portion B, in which the ink conveyer tubes  34  are connected to the first inkjet heads  21 , are held in substantially an even level by the first arm  36 . Therefore, the ink conveyer tubes  34  can be maintained within the same horizontal plane regardless of the operating motions of the first inkjet heads  21 . 
     It is to be noted, in  FIG. 1 , the ink conveyer tubes  34  being held by the first arm  36  are indicated in solid lines for simplicity in description; however, in the present embodiment, the ink conveyer tubes  34  are held along a downward surface of the first arm  36 . 
     Further, as shown in  FIG. 3 , the ink conveyer tubes  34  are arranged within a vertical range between a top surface of the first arm  36  and a bottom level of the first cartridges  31  so that the level differences to be caused in the ink conveyer tubes  34  can be maintained small. 
     Furthermore, as shown in  FIG. 2 , the first arm  36  to hold the ink conveyer tubes  34  for the white ink are in a lower position than the second arm  37  to hold the ink conveyer tubes  35  for the CMYK colored inks. Therefore, the level differences which may be caused in the ink conveyer tubes  34  can be maintained to be smaller than the level differences which may be caused in the ink conveyer tubes  35 . Because the first arm  36  is arranged in the lower position than the second arm  37 , a length in the ink conveyer tubes  34  from the first cartridges  31  to the first inkjet heads  21  can be shorter than a length in the ink conveyer tubes  35  from the second cartridges  32  to the second inkjet heads  22  so that the distance in which the white ink travels within the ink conveyer tubes  34  can be shorter. 
     According to the above configuration, uneven distribution of the white ink in the ink conveyer tubes  34  can be reduced even when the white ink contains oxidized titanium and therefore has higher density of pigment with respect to densities of pigments in the other colored inks. Thus, uneven concentration of the colorants can be prevented from occurring, and concentration gradient of the white ink within the ink conveyer tubes can be smaller. Accordingly, irregular ejection of the white ink from the first inkjet heads  21 , insufficient flow of the ink flow to the first inkjet heads  21 , or uneven densities of the color in a formed image can be prevented. 
     Additionally, in the present embodiment, the first arm  36  to hold the first inkjet heads  21  for white ink and the second arm  37  to hold the second inkjet heads  22  for CMYK colored inks are separately arranged in the respective (right or left) sides within the chassis  10 ; therefore, even without the guide rails  11 ,  12  being not separated apart from each other, the ink conveyer tubes  34  and  35  can be prevented from interfering each other when the carriages  13  and  14  are respectively driven. 
     When an image is printed in the inkjet printer  1  according to the embodiment, and the first and the second arms  36 ,  37  are operated as shown in  FIGS. 5A-5E , the recording medium is fed from the rear side toward the front side of the inkjet printer  1  (i.e., from the right-hand side toward the left-hand side in  FIGS. 5A-5E ). Simultaneously, the carriage  13  is moved from the lower side to the upper side in  FIGS. 5A-5E , and the carriage  14  is moved from the upper side to the lower side in  FIGS. 5A-5E . Therefore, the image is formed on the recording medium firstly in the white ink and in the CMYK inks thereafter over the white layer. During the above operation shown in  FIGS. 5B and 5C , the second arm  37  crosses over the first arm  36  in the plan views; however the first arm  36  and the second arm  37  are arranged in vertically different levels so that the ink conveyer tubes  34  and  35  do not interfere each other. 
     Although an example of carrying out the invention has been described, those skilled in the art will appreciate that there are numerous variations and permutations of the printing apparatus that fall within the spirit and scope of the invention as set forth in the appended claims. It is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or act described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims. 
     In the above embodiment, the first and the second arms  36 ,  37  include two-segmented portions; however, the arms may include more than two segments as long as each of the arms are deformable according to movements of the inkjet heads  21 ,  22  within a same horizontal plane. For example, the arms may be extended and contracted in a caterpillar style or an accordion-folded style.