Abstract:
The invention provides an ink jet color recording apparatus capable of forming a good image by preventing solidification of ink. The ink jet color recording apparatus has a recovery step of recovering the injection function of a black nozzle by recovering black ink (pigment ink) remaining in the black nozzle into a black cap, and a supply step of supplying color ink (dye ink) to the black cap after the recovery step. Thus, the pigment ink recovered into the black cap by the recovery step can be made into mixed ink hard to dry, and further ink adhering to the inner wall of a suction hose connected to the black cap can be made into mixed ink residue hard to dry.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a small-sized ink jet color recording apparatus adapted to fly ink to a recording medium by an ink jet method to form a color image. 
     2. Description of the Related Art 
     As shown in FIG. 11, the conventional ink jet color recording apparatus  80  is so constructed that a recording head  82  (hereinafter simply referred to as head  82 ) is reciprocated along a guide  84  and with recording paper P transported in the direction U intersecting perpendicularly to the reciprocating direction W of the head, dye ink is flown according to the image information to form an image. 
     As shown in FIG. 12, the head  82  is provided with a storing part  86 B for storing black ink, a storing part  86 C for storing color ink, a nozzle  88 B for discharging black ink, and a nozzle  88 C for discharging color ink. 
     As the nozzles  88 B,  88 C have a small diameter, ink is dried to easily cause clogging. Therefore, frequently the ink is jammed not to be flown so that a desired image cannot be formed. As a countermeasure, generally, a maintenance part  89  (see FIGS. 11 and 12) having a suction system is provided, whereby when the image quality is lowered, ink in the nozzles  88 B,  88 C is sucked and removed to recover the injection function of the nozzles  88 B,  88 C. 
     The inventors have, as shown in FIG. 13, invented an ink jet color recording apparatus  90  adapted to suck ink by one small-sized suction pump  92  and filed an application for it. The contents of the invention are disclosed in Japanese Published Unexamined Patent Application No. Hei 10-067121. 
     The apparatus  90  is provided with a cap member  94 B corresponding to the nozzle  88 B and a cap member  94 C corresponding to the nozzle  88 C. Hoses  96 B,  96 C as an ink suction path are respectively connected to the bottoms of the cap members  94 B and  94 C, and the other ends of the hoses  96 B,  96 C are respectively connected to a first suction port  98  and a second suction port  99  of the suction pump  92 . 
     The ink jet color recording apparatus  90  is so constructed that suction of the nozzle  88 B and suction of the nozzle  88   c  are individually performed by the small-sized suction pump  92 . 
     Recently, however, ink (pigment ink) mainly including pigment ingredients has been used to strengthen the water resisting property of ink. The pigment ink is more liable to dry than the dye ink used heretofore. Consequently, it has a disadvantage in that ink is solidified in the cap members  94 B,  94 C, so ink in the nozzles  88 B,  88 C is not sufficiently removed. Further, in sucking, ink adheres to the inner wall or the like of the hoses  96 B,  96 C to become solid ink residue  100 , which results in the disadvantage that the function of the maintenance part  89  is not exhibited sufficiently. 
     SUMMARY OF THE INVENTION 
     The present invention has been made in view of the above circumstances and provides an ink jet color recording apparatus capable of forming a favorable image by preventing solidification. 
     According to an aspect of the present invention, the ink jet color recording apparatus has plural ink tanks for respectively storing ink different in composition; plural recording heads each having a nozzle for injecting ink in the ink tanks; and a cap member for recovering ink in the nozzle, wherein the ink jet color recording apparatus comprises: a recovery step of recovering the injection function of the nozzle by recovering ink in the nozzle into the cap member; and the supply step of supplying ink different in composition from the ink in the nozzle to the same cap member after the recovery step. 
     The ink in the nozzle is recovered into the cap member by the recovery step. Then, ink different in composition from the ink is supplied to the same cap member by the supply step to mix the ink in the cap member. 
     Thus, the ink recovered in the cap member is made into the mixed ink hard to dry so that the ink is hard to be solidified. 
     According to another aspect of the invention, the ink jet color recording apparatus is characterized in that ink of different compositions is pigment ink and dye ink. 
     The pigment ink which is easy to dry so that it is liable to be solidified is mixed with the dye ink in the cap member so that the density is lowered. Thus, the ink is made into mixed ink hard to dry, that is, hard to be solidified. 
     According to another aspect of the invention, the ink jet color recording apparatus is characterized in that the recovery step is the step of sucking ink from the nozzle. 
     This suction is frequently performed when an abnormal image is formed. 
     The injection function of the nozzle can be surely recovered. 
     In the ink jet color recording apparatus of the invention, however, when the recovery step is performed, sometimes ink adheres to the inner wall of the suction system used in suction and such adhering ink (hereinafter referred to as adhering ink) is easy to dry. Accordingly, after the supply step, the suction step of sucking ink staying in the cap member is performed, whereby the staying ink and the adhering ink are mixed so that the composition of the adhering ink is made into mixed ink hard to dry so as to sufficiently secure the sucking force of the suction system. 
     According to another aspect of the invention, the ink jet color recording apparatus is characterized in that the recovery step is the step of blank-injecting ink from the nozzle. 
     This blank injection is often performed periodically. 
     After the supply step performed after the recovery step, the suction step of sucking ink staying in the cap member may be performed. Thus, the mixed ink staying in the cap member can be immediately removed. 
     According to another aspect of the invention, the method for recovering ink-jet recording head having the following steps: vacuuming a pigment-base liquid ink form a nozzle into a cap member having a ink guide tube (hose);and supplying a dye-base liquid ink into the ink guide tube through the cap member. 
     According to another aspect of the invention, the ink-jet recording apparatus having a recording head having a nozzle for injecting an pigment-base ink; a cap member for recovering the ink in the nozzle; an ink guide tube (hose) connected to the cap member; and an ink supplying device that supply a dye-base ink into the ink guide tube through the cap member. 
     The ink supplying device may be a second recording head having the dye-base ink. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Preferred embodiments of the present invention will be described in detail based on the followings, wherein. 
     FIG. 1 is a perspective view of an ink jet color recording apparatus according to a first embodiment of the invention; 
     FIG. 2 is an enlarged perspective view of a maintenance part of the ink jet color recording apparatus according to the first embodiment of the invention; 
     FIG. 3 is a sectional view showing the constitution of the ink jet color recording apparatus according to the first embodiment of the invention; 
     FIG. 4 is a flowchart showing the procedure of performing maintenance on a nozzle in the first embodiment; 
     FIG. 5 is a sectional view showing the condition where black ink in a black nozzle is sucked and discharged in the first embodiment; 
     FIG. 6 is a sectional view showing that color ink is blank-discharged to a black cap in the first and second embodiments; 
     FIG. 7 is a sectional view showing the condition where a color nozzle part is positioned right over the black cap in the first and second embodiments; 
     FIG. 8 is a sectional view showing that mixed ink staying in the black cap is sucked and discharged in the first and second embodiments; 
     FIG. 9 is a flowchart showing the procedure of performing maintenance on a nozzle in the second embodiment; 
     FIG. 10 is a sectional view showing that black ink is blank-discharged to the black cap in the second embodiment; 
     FIG. 11 is a perspective view of the conventional ink jet color recording apparatus; 
     FIG. 12 is a sectional view showing the constitution of the conventional ink jet color recording apparatus; and 
     FIG. 13 is a sectional view showing the constitution of the conventional ink jet color recording apparatus. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     As shown in FIG. 1, a first embodiment of an ink jet color recording apparatus is provided with a recording head  22  (hereinafter referred to as head  22  simply) adapted to reciprocate along a guide  21  while injecting ink, a transport mechanism  26  for transporting recording paper P in the direction U intersecting perpendicularly to the reciprocating direction W, and a maintenance part  28  (see FIG. 2) for recovering the function of the head  22 . 
     The head  22  has black pigment ink (hereinafter referred to as black ink) stored in a black ink storing container  32  and color dye ink (hereinafter referred to as color ink) stored in a color ink storing container  34 . 
     As shown in FIG. 3, the color ink storing container  34  is provided with storing parts  34 Y,  34 M,  34 S for respectively storing color ink of yellow, magenta and cyan and a nozzle part  36 C (hereinafter referred to as color nozzle part  36 C) for discharging color ink fed from each storing part. A nozzle  38 C for discharging color ink (hereinafter referred to as color nozzle  38 C) is formed on the color nozzle part  36 C. 
     A black ink storing container  32  is also similarly provided with a storing part  32 B for storing black ink and a nozzle part  36 B for discharging black ink (hereinafter referred to as black nozzle part  36 B) fed from the storing part  32 B, and a nozzle  38 B for discharging black ink (hereinafter referred to as black nozzle part  38 B) is formed on the black nozzle part  36 B. 
     The color nozzle  38 C and the black nozzle  38 B are both constituted by forming plural nozzles in line. 
     On the other hand, a maintenance part  28  is so constructed that when an abnormal image is formed in recording paper P (see FIG.  1 ), ink clogging of the head  22  is eliminated by the maintenance part  28 . 
     As shown in FIG. 3, the maintenance part  28  is provided with a black cap  50 B and a color cap  50 C which respectively collect black ink blank-discharged from the black nozzle part  36 B and color ink blank-discharged from the color nozzle part  36 C as a cap member, and both caps are both held on a cap carriage  52  with an opening thereof upward. The cap carriage  52  is capable of moving in the vertical direction V. 
     The black cap  50 B and the color cap  50 C respectively accommodate a sponge body  54 B and a sponge body  54 C for absorbing ink and retaining it. 
     Further, the maintenance part  28  includes a suction pump  60  disposed below the black cap  50 B and the color cap  50 C for discharging ink. An ink discharge port  51 B formed in the cap bottom of the black cap  50 B and a first suction port  62 B of the suction pump  60  are connected to each other by a hose  66 B, and sucked ink is discharged and absorbed in a discharged ink absorber  70 . Similarly in the color cap  50 C, an ink discharge port  51 C of the cap bottom and a second suction port  52 C of the suction pump  60  are connected to each other by a hose  66 C. 
     When an abnormal image is formed on recording paper P (see FIG.  1 ), a user of the ink jet color recording apparatus  20  gives the command of maintenance on the black nozzle part  36 B to the apparatus  20 . In response to the command, according to the procedure of the flowchart shown in FIG. 4, the maintenance on the black nozzle part  36 B is performed. 
     First, the instruction that black ink is sucked is given from the ink jet color recording apparatus  20 . Consequently the head  22  is moved to locate the black nozzle part  36 B right above the black cap  50 B and stopped, and further the cap carriage  52  is moved upward so that the black cap  50 B is sealed by the black nozzle part  36 B (see FIG.  5 ). 
     Subsequently, by the suction operation of the suction pump  60 , black ink in the black nozzle  38 B is discharged through the black cap  50 B, the hose  66 B and further the suction pump  60  (recovery step of FIG.  4 ), and absorbed in the discharged ink absorber  70 . In the state of ending the recovery step, as shown in FIG. 5, residue of black ink (hereinafter referred to as black ink residue) remains in the sponge body  54 B, and also black ink residue  72 B adheres to the inner all of the hose  66 B. 
     After the end of the recovery step, the black cap  50   b  is opened to the air, and the cap carriage  52  is moved downward to return to its original position. 
     Next, the instruction that color ink is blank-discharged to the black cap  50 B is given. Consequently, the head  22  is moved to locate the color nozzle  38 C in the center of the black cap  50 B and stopped, and subsequently, as shown in FIG. 6, color ink which is dye ink is blank-discharged from the color nozzle  38 C (supply step of FIG.  4 ). The blank discharge amount is set to a suitable amount in advance. 
     The blank-discharged color ink is absorbed in the sponge body  54 B, and the black ink residue in the sponge body  54   b  is mixed with the color ink to become mixed ink. The mixed ink is hard to dry in the sponge body  50 B because the density of black ink is low. 
     Further, given is the instruction that the black cap  50 B is sealed by the color nozzle part  36 C to absorb ink. Consequently, as shown in FIG. 7, the head  22  is a little moved to locate the color nozzle part  36 C right above the black cap  50 B and stopped. 
     The cap carriage  52  is moved upward, and the black cap  50 B is sealed by the color nozzle part  36 C (see FIG.  8 ). 
     Subsequently, the mixed ink absorbed in the sponge body  54 B is absorbed through the hose  66 B and the black cap  50 B by the suction pump  60  (suction step of FIG.  4 ). 
     Thus, the mixed ink is removed from the sponge body  54 B, and the black ink residue  72 B (FIGS. 5 to  7 ) adhering to the inner wall of the hose  66 B is diluted with the mixed ink and simultaneously sucked and discharged. Accordingly, the ink adhering to the inner wall of the hose  66 B becomes mixed ink residue  72 M instead of the black ink residue  72 B (see FIG.  8 ). 
     The mixed ink residue  72 M is hard to dry because the density of black ink is low. 
     Since the black ink is sucked from the sponge body  54 B by the recovery step in the first embodiment, the supply amount of color ink supplied at the supply step may be remarkably smaller as compared with that in a second embodiment to be mentioned later. 
     A second embodiment will now be described. The ink jet color recording apparatus of the second embodiment is so constructed that as maintenance on the nozzle, ink (especially black ink which is pigment ink) is periodically and automatically blank-discharged from the nozzle to prevent clogging of the nozzle. The apparatus is different from the first embodiment of the ink jet color recording apparatus  20  (see FIGS. 1 to  3 ) in command in performing maintenance, but they have the basically same components. Therefore, in the second embodiment, the same reference numerals designate the same components as those of the first embodiment, so the description will be omitted. 
     The following description deals with the operation at the time of giving the command (periodic command) that black ink is blank-discharged from the black nozzle part  36 B from the ink jet color recording apparatus of the second embodiment as maintenance on the nozzle as shown in FIG.  9 . 
     When this command is given, first, the black ink blank discharge instruction is given. Consequently, as shown in FIG. 10, the head  22  is moved to locate the black nozzle  38 B right above the black cap  50 B and stopped, and further black ink (pigment ink) is blank-discharged from the black nozzle  38 B (recovery step of FIG.  9 ). The blank discharge amount of black ink is set to a suitable amount in advance. 
     The blank-discharged black ink is absorbed in the sponge body  54 B. 
     Secondly, the instruction that color ink is blank-discharged to the black cap  50 B is given. Consequently, the head  22  is moved to locate the color nozzle  38 C at the center of the black cap  50 B and stopped, and subsequently, as shown in FIG. 6, color ink which is dye ink is blank-discharged from the color nozzle  38 C (supply step of FIG.  9 ). The blank-discharged color ink is absorbed in the sponge body  54 B of the black cap  50 B. 
     Thus, the black ink (pigment ink) absorbed in the sponge body  54 B is mixed with color ink (dye ink) to lower the density, so that the mixed ink hard to dry is made. The blank discharge amount of color ink is set in advance to a suitable amount so that the black ink density in the mixed ink is equal to or lower than a designated density. 
     After that, given is the instruction that the black cap  50 B is sealed by the color nozzle part  36 C to absorb ink. Consequently, the head  22  is a little moved to locate the color nozzle part  36 C right above the black cap  50 B and stopped (see FIG.  7 ). 
     Then, the cap carriage  52  is moved upward, and the black cap  50 B is sealed by the color nozzle part  36 C (see FIG.  8 ). 
     Subsequently, the mixed ink staying in the sponge body  54 B is sucked through the hose  66 B and the black cap  50 B by the suction pump  60  (suction step of FIG.  9 ). 
     Since this mixed ink is hard to dry, the mixed ink residue  72 M adhered to the inner wall of the hose  66 B by the suction is hard to be solidified. Accordingly, the function of the maintenance part  28  can be kept sufficiently. 
     Though the description of the first and the second embodiments deals with maintenance on the black nozzle part  36 B only, the ink jet color recording apparatus described in the embodiments of the invention is adapted to also perform maintenance on the color nozzle part  36 C. 
     In performing maintenance on the color nozzle part  36 C, color ink is periodically blank-discharged from the color nozzle part  36 C toward the color cap  50 C (see FIG.  3 ). The blank-discharged color ink is absorbed in the sponge body  54 C of the color cap  50 C. After that, the color cap  50 C is sealed by the color nozzle part  36 C, and the color ink absorbed in the sponge body  54 C is sucked and discharged through the hose  66 C by the suction pump  60 . 
     Since black ink (pigment ink) will not be discharged to the color cap  50 C, it is not necessary to fear that ink may be rapidly solidified in the color cap  50 C or on the inner wall of the hose  66 C (see FIG.  3 ). 
     The entire disclosure of Japanese Patent Application No. 2000-65974 filed on Mar. 10, 2000 including specification, claims, drawings and abstract is incorporated herein by reference in its entirety.