Tube pump and liquid ejecting apparatus

Abstract

A tube pump including a housing with a cylindrical inner circumferential surface, wherein a portion of a flexible tube is wound with an upstream portion and a downstream portion of the tube overlapping at a overlapping section, and a pressing member capable of pressing the tube which is movably housed along the inner circumferential surface. The housing includes a relief portion for releasing either the upstream portion or the downstream portion from the pressing of the pressing member, wherein the relief portion is formed on the inner circumferential surface at a position which corresponds to the position of tube overlapping section.

1 . A tube pump comprising:
 a housing with cylindrical inner surface wherein a portion of a flexible tube is wound along the cylindrical inner surface of the housing with an upstream portion and a downstream portion of the tube partially overlapping at a tube overlapping portion, the housing including a pressing member for compressing the portion of the tube along the inner circumferential surface;   wherein the housing includes a relief portion for releasing either the upstream portion or the downstream portion from the pressing of the pressing member located along the cylindrical inner surface at a position which corresponds to the location of the overlapping tube.   
   
   
       2 . The tube pump according to  claim 1 , wherein the relief portion includes an upstream relief portion and a downstream relief portion which correspond to the upstream portion and the downstream portion of the tube overlapping portion. 
   
   
       3 . The tube pump according to  claim 2 , wherein the upstream relief portion and the downstream relief portion are formed in the inner circumferential surface. 
   
   
       4 . The tube pump according to  claim 1 , wherein the overlapping portion of the flexible tube is more flexible than other portions of the flexible tube. 
   
   
       5 . The tube pump according to  claim 1 , further comprising a rotating body which is capable of rotating about an axis passing through the center of the housing,
 wherein the rotating body has a cam surface that comes into contact with the pressing member when the pressing member moves between a pump operating position wherein the tube is compressed in order to generate a negative pressure and a pump non-operating position wherein the tube is compressed so as not to generate the negative pressure, and   wherein the frictional resistance of the cam surface varies.   
   
   
       6 . The tube pump according to  claim 5 , wherein the pressing member has a shaft that comes into contact with the cam surface of the rotating body, and
 wherein the frictional resistance of the portion of the shaft which comes in sliding contact with the cam surface is lower than other portions of the shaft.   
   
   
       7 . A liquid ejecting apparatus comprising:
 a liquid ejecting head which is capable of ejecting a liquid from a nozzle formed on a nozzle formation surface;   a cap which is capable of sealing the nozzle formation surface; and   a sucking mechanism which is capable of sucking the liquid from the cap,   wherein the sucking mechanism includes the tube pump according to  claim 1 .   
   
   
       8 . A liquid ejecting apparatus comprising:
 a liquid ejecting head which is capable of ejecting a liquid from a nozzle formed on a nozzle formation surface;   a cap which is capable of sealing the nozzle formation surface; and   a sucking mechanism which is capable of sucking the liquid from the cap, a flexible tube and tube pump located near the middle of the flexible tube;   wherein the tube pump comprises a housing with cylindrical inner surface wherein a portion of the flexible tube is wound along the cylindrical inner surface of the housing with an upstream portion and a downstream portion of the tube partially overlapping at a overlapping portion, and a pressing member for compressing the portion of the tube along the inner circumferential surface;   wherein the housing includes a relief portion including a upstream relief portion and a downstream relief portion for releasing either the upstream portion or the downstream portion from the pressing of the pressing member, the relief portions being located along the cylindrical inner surface at positions which correspond to the location of the upstream portion and downstream portion of the overlapping portion.   
   
   
       9 . The apparatus according to  claim 8 , wherein the overlapping portion of the flexible tube is more flexible than other portions of the flexible tube. 
   
   
       10 . The apparatus according to  claim 8 , further comprising a rotating body which is capable of rotating about an axis passing through the center of the housing,
 wherein the rotating body has a cam surface that comes into contact with the pressing member when the pressing member moves between a pump operating position wherein the tube is compressed in order to generate a negative pressure and a pump non-operating position wherein the tube is compressed so as not to generate the negative pressure, and   wherein the frictional resistance of the cam surface varies.   
   
   
       11 . The apparatus according to  claim 10 , wherein the pressing member has a shaft that comes into contact with the cam surface of the rotating body, and
 wherein the frictional resistance of the portion of the shaft which comes in sliding contact with the cam surface is lower than other portions of the shaft.