Ink jet recording head

Abstract

An ink jet recording head is provided with a flow path structure capable of enhancing the discharge power, filtering performance, and discharge frequency characteristics even with liquid droplets being made small. The flow path structure thus provided in a supply path makes the flow path sectional area right angled to the liquid flow direction small, and changes the area (shape) thereof at the same time. The flow path structure is formed by a flat square column serving as a first structure for closing a part of the supply path, and plural columns serving as a second structure for closing a part of the supply path. The square column is formed on the base plate in the entire width thereof to close the supply path on the base plate side. The plural columns are arranged on the square column symmetrically with respect to the center of the supply path, and extended from the square column to the discharge port plate in the height direction of the supply path.

1. An ink jet recording head comprising:
 an element base plate provided with plural discharge energy-generating elements for generating bubbles in liquid by thermal energy, and a through-opening becoming a supply chamber for leading liquid to said discharge energy-generating elements; and  
 a flow-path-forming base plate (i) for forming (a) plural bubbling chambers containing said discharge energy-generating elements, respectively, on a surface of said element base plate having said discharge energy-generating elements formed thereon, and (b) plural supply paths for leading liquid to said bubbling chambers, respectively, and (ii) having plural nozzles provided therefor corresponding to said bubbling chambers, respectively, to enable said bubbling chambers to be communicated with the outside of the head, wherein  
 a diameter of each of said nozzles is not greater than a distance between the surface of said element base plate on which said discharge energy-generating elements are formed and a surface of said flow-path-forming base plate opposed to the surface on which said discharge energy-generating elements are formed in said respective supply path,  
 said ink jet recording head is provided with a flow path structure so configured that, for each of said supply paths, a cross-sectional area thereof perpendicular to a liquid flow direction is smallest between said respective bubbling chamber and the through-opening,  
 and said flow path structure is provided with (i) a first structure for closing a part of each of said supply paths, said first structure being formed on the surface of said element base plate having said discharge energy-generating elements formed thereon, and (ii) a second structure formed on said flow-path-forming base plate to be a columnar structure extending from said first structure, said second structure also being for closing a part of each of said supply paths.  
 
     
     
       2. An ink jet recording head according to  claim 1 , wherein a shape of a portion of a supply path cross-section perpendicular to the liquid flow direction having the smallest cross-sectional area is square. 
     
     
       3. An ink jet recording head according to  claim 1 , wherein said first structure comprises one or more square columns, and said second structure comprises one or more columns. 
     
     
       4. An ink jet recording head according to  claim 1 , wherein the bubbles generated by said discharge energy-generating elements are communicated with the air outside for discharging liquid droplets. 
     
     
       5. An ink jet recording head comprising:
 an element substrate having a plurality of discharge energy-generating elements for generating bubbles in liquid by thermal energy and a through-opening becoming a supply chamber for leading liquid to said discharge energy-generating elements;  
 a discharge port plate opposed to said element substrate and having a plurality of discharge ports opposed to said plurality of discharge energy-generating elements, respectively;  
 a plurality of supply paths provided in a space sandwiched by said element substrate and said discharge port plate, for supplying liquid to said plurality of discharge ports, respectively, from said through-opening;  
 a plurality of columnar structures provided for said plurality of supply paths, respectively, and extending from a side of said element substrate to a side of said discharge port plate,  
 wherein, for each of said supply paths, a diameter of said discharge port is not greater than a height of said supply path, and  
 for each of said supply paths, one end of said respective columnar structure is provided on a structural member formed in said supply path to extend across an entire width of the supply path observed from a cross-section of the supply path perpendicular to a direction in which said supply path extends, so that a length of a gap between adjacent columns of said columnar structure, in a height direction of said supply path, is shorter than a diameter of said discharge port.  
 
     
     
       6. An ink jet recording head comprising:
 an element substrate having a plurality of discharge energy-generating elements for generating bubbles in liquid by thermal energy and a through-opening becoming a supply chamber for leading liquid to said discharge energy-generating elements;  
 a discharge port plate opposed to said element substrate and having a plurality of discharge ports opposed to said plurality of discharge energy-generating elements, respectively;  
 a plurality of supply paths provided in a space sandwiched by said element substrate and said discharge port plate, for supplying liquid to said plurality of discharge ports, respectively, from said through-opening;  
 a plurality of columnar structures provided corresponding to said plurality of supply paths, respectively, each of said columnar structures being disposed between an end portion of a respective supply path at a side of said through-opening and said through-opening, said columnar structures extending from a side of said element substrate to a side of said discharge port plate,  
 wherein, for each of said supply paths, a diameter of said discharge port is not greater than a height of said supply path, and  
 for each of said supply paths, one end of said respective columnar structure is formed on a structural member that has a width larger  greater than a width of said supply path, observed from a cross-section of said supply path perpendicular to a direction in which said supply path extends, and is formed on a  said structural member being formed between a side  the end portion of said supply path at the side of said through- opening  and said through-opening, so that a length of a gap between adjacent columns of said columnar structure, in a height direction of said supply path, is shorter than a diameter of said discharge port.