Printer with floating print head with alignment surfaces to position printhead

Abstract

A printhead assembly for a printer with the printhead mounted in the lid of the printer and the platen mounted in the body of the printer. The printhead is spring loaded, permitting it to float in both the vertical and horizontal directions within the lid assembly. Guideposts are located in the body of the printer with a defined positional relationship to the platen. When the lid is closed, the guideposts position the printhead in its correct position with respect to the platen. Mounting the printhead in the lid and the platen in the printer body permits new paper to be loaded quickly and easily by simply pulling the paper past the platen and closing the lid. The cumbersome paper-threading procedure of conventional inexpensive printers is avoided.

What is claimed is:  
     
       1. A printer, comprising: 
       a base; 
       a lid pivotally coupled to the a base, the lid and having an open position and a closed position, the pivotal coupling defining a longitudinal axis;  
       a platen rotatably coupled to the said base;  
       a floating printhead assembly resiliently coupled to the mechanism carried by said lid and , said floating printhead mechanism having an t least one alignment surface rigidly connected to the assembly, said printhead assembly being adapted to resiliently press against said platen disposed approximately at an oblique angle from a reference plane defined by said longitudinal axis and a point on the bottom of said floating printhead mechanism when said lid is in the said closed position; and  
       at least one guidepost fixedly coupled to alignment surface on said base, said guidepost having an oblique guidepost alignment edge adapted to make parallel contact with said at least one alignment surface of said floating printhead mechanism assembly alignment surface when said lid is being closed, whereby the contact between the oblique guidepost alignment edge and the printer alignment surface to causes the said floating printhead assembly mechanism to resiliently align with said platen.  
     
     
       2. The printer of  claim 1 , wherein the said platen includes is a cylindrical roller rotatably coupled to the said base. 
     
     
       3. The printer of  claim 1 , wherein said floating printhead assembly mechanism comprises a plurality of print elements arranged in a linear pattern, said guidepost being adapted to align said printhead assembly with said platen in a position that the print elements are positioned in a predetermined distance from and positioned away from a line of contact defined as the area of maximum pressure between said floating printhead assembly mechanism and said platen when the said lid is in the said closed position. 
     
     
       4. The printer of  claim 3 , wherein the plurality of said print elements are a plurality of thermal print elements. 
     
     
       5. The printer of  claim 3 , wherein the predetermined distance is between about 2 and about 22 thousandths of an inch said print elements are positioned  0 . 012 ± 0 . 010  inches forward of said line of contact. 
     
     
       6. The printer of  claim 1 , wherein the printhead assembly includes a spring further comprising means for biasing the said floating printhead assembly mechanism towards the said platen and for adjusting orientation of the printhead assembly when the said lid is in the said closed position. 
     
     
       7. The printer of  claim 6 , wherein the spring is a leaf said biasing means includes at least one spring coupled between said lid and said printhead mechanism. 
     
     
       8. The printer of  claim 1 , further comprising a pair of latches respectively coupled to means for latching said lid near opposite ends, said pair of latches being adapted to latch said lid with to said base by inserting said pair of latches into corresponding latch holes on the base . 
     
     
       9. The printer of  claim 8 , further comprising wherein said latching means includes a pair of latches coupled to said lid and adapted to engage a corresponding pair of latch recesses on said base when said lid is in said closed position and a latch release coupled to said pair of latches for turning said latches to release said lid from said base . 
     
     
       10. The A printer of  claim 1 , wherein: , comprising: 
       
         a base; 
       
       thea lid is pivotally coupled to the said base with by way of a hinge having a longitudinal axis, said lid having an open position and a closed position;  
       the printhead assembly alignment surface defines an oblique angle from a horizontal plane when the lid is in the closed position; and  
       the guidepost alignment edge has approximately the same oblique angle from the horizontal plane  
       a platen rotatably coupled to said base;  
       
         a printhead resiliently coupled to said lid and having an alignment surface disposed at an oblique angle from a reference plane defined by said longitudinal axis and a point on the bottom of said printhead when said lid is in said closed position; and  
       
       
         at least one guidepost coupled to said base and having an alignment surface disposed approximately at the same oblique angle from said reference plane and adapted to contact said printhead alignment surface when said lid is being closed to cause said resiliently coupled printhead to align with said platen.  
       
     
     
       11. The printer of  claim 10 , wherein: the oblique angle is between about 77-83 degrees and about 83 degrees when measured from the horizontal said reference plane. 
     
     
       12. The printer of  claim 1 , wherein the printer comprises two guideposts respectively positioned on said base near opposite ends of said printhead assembly when said lid is closed, said guideposts each having an oblique guidepost alignment edge respectively contacting and aligning said printhead assembly against said platen. 
     
     
       13. A method of aligning a printhead with a platen in a printer, comprising the steps of: 
       closing a printer lid onto a printer base;  
       moving a printhead towards a platen when the lid is being closed;  
       contacting a printhead alignment edge with a guidepost alignment edge before the lid closes; and  
       aligning the printhead with the platen by the step of contacting.  
     
     
       14. A printhead alignment system, comprising: 
       ( a )  a base;    
       ( b )  a lid adapted to close onto said base;    
       ( c )  a platen operatively coupled to said base;    
       ( d )  a printhead assembly adapted to float within said lid, said floating printhead assembly adapted to descend over said platen in a substantially linear direction of travel immediately before said lid closes onto said base; said floating printhead assembly including at least one alignment surface disposed at an oblique angle relative to said direction of travel, said printer base being adapted to make parallel contact with said at least one alignment surface to cause said printhead assembly to align with said platen.   
     
     
       15. A printhead alignment system, comprising: 
       ( a )  a base;    
       ( b )  a lid adapted to close onto said base;    
       ( c )  a platen operatively coupled to said base;    
       ( d )  a printhead assembly adapted to float within said lid, said floating printhead assembly adapted to descend over said platen in a substantially linear direction of travel immediately before said lid closes onto said base, said floating printhead assembly including a first alignment surface disposed at an oblique angle relative to said direction of travel, said printer base including a second alignment surface adapted to make parallel contact with said first alignment surface to cause said printhead assembly to align with said platen.   
     
     
       16. A printhead alignment system, comprising: 
       
         a base;  
       
       
         a lid pivotally coupled at one end to said base by way of a hinge having a longitudinal axis, said lid having an open position and a closed position;  
       
       
         a platen rotatably coupled to said base;  
       
       
         a printhead resiliently coupled to said lid and having a first surface facing away from said pivotally coupled end and being disposed at an oblique angle from a reference plane defined by said longitudinal axis and a point on the bottom of said printhead when said lid is in said closed position; and  
       
       
         at least one printhead alignment surface on said base disposed approximately at the same oblique angle from said reference plane and adapted to contact said first surface of said printhead as said lid is being closed to cause said resiliently coupled printhead to align with said platen. 
       
     
     
       17. A printhead alignment system, comprising: 
       
         a base;  
       
       
         a lid pivotally coupled at one end to said base by way of a hinge having a longitudinal axis, said lid having an open position and a closed position;  
       
       
         a platen rotatably coupled to said base;  
       
       
         a printhead resiliently coupled to said lid and having a first surface facing away from said pivotally coupled end and being disposed at an oblique angle from a reference plane defined by said longitudinal axis and a point on the bottom of said printhead when said lid is in said closed position; and  
       
       
         at least two printhead alignment surfaces on said base disposed respectively near opposite ends of said printhead when said lid is in said closed position and approximately at the same oblique angle from said reference plane and adapted to contact said first surface of said printhead as said lid is being closed to cause said resiliently coupled printhead to align with said platen. 
       
     
     
       18. The printer of  claim 3 , wherein the positioning of said print elements with respect to said platen is controlled by the distance between said print elements and said at least one alignment surface of said floating printhead mechanism, and the distance between said at least one alignment surface on said base and said line of contact.