Thermally caulked combined structure, method of thermal caulking, and image sensor unit and image reading apparatus using the same

Abstract

In an image reading apparatus incorporating a CIS unit warped by heat shrinkage of a thermoplastic resin molded product, the optical distances from a read line to a photoelectric conversion element in the center and the two end portions in the longitudinal direction of the photoelectric conversion element are different. A thermally caulked combined structure is obtained by fixing an object to be fixed by thermal caulking by thermally deforming a plurality of caulking projections formed in the longitudinal direction of a molded product made of a thermoplastic resin and having a rectangular parallelepiped outer shape. Antiwarping grooves ( 15 ) are formed apart from the proximal portion of each caulking projection ( 12 ) of the molded product ( 4 ) before thermal caulking so as to sandwich the projection.

1 . A thermally caulked combined structure obtained by fixing an object to be fixed by thermal caulking by thermally deforming a plurality of caulking projections formed in a longitudinal direction of a molded product made of a thermoplastic resin and having a rectangular parallelepiped outer shape,
 wherein on a surface of the molded product before thermal caulking, the plurality of caulking projections are almost linearly arranged in the longitudinal direction of the molded product, and an antiwarping groove is formed in a position apart from a proximal portion of each caulking projection.   
     
     
         2 . A thermally caulked combined structure according to  claim 1 , wherein the position apart from the proximal portion is determined on the basis of shapes of a caulking jig for use in caulking manufacture and the caulking projection. 
     
     
         3 . A thermally caulked combined structure according to  claim 1 , wherein the molded product has a frame surrounding end faces of the object to be fixed, and the plurality of caulking projections are formed on an upper surface of the frame. 
     
     
         4 . A thermally caulked combined structure according to  claim 1 , wherein
 the plurality of caulking projections are formed on a surface of the molded product, which is to be connected to the object to be fixed, and each caulking projection is thermally caulked after being inserted through and protruded from a hole formed in the object to be fixed.   
     
     
         5 . A thermally caulked combined structure according to  claim 4 , wherein the molded product has a frame surrounding end faces of the object to be fixed. 
     
     
         6 . A thermally caulked combined structure according to  claim 3 , wherein the caulking projection is deformed to be substantially leveled with an upper surface of the frame after the thermal caulking. 
     
     
         7 . A thermally caulked combined structure according to  claim 1 , wherein the antiwarping groove has a structure which reduces heat conduction from the caulking projection to a portion outside the antiwarping groove during the thermal caulking. 
     
     
         8 . A thermally caulked combined structure according to claim,  1 , wherein the thermoplastic resin is polycarbonate. 
     
     
         9 . An image sensor unit comprising:
 a thermally caulked combined structure as set forth in  claim 1  and having a hollow portion in which a substrate as an object to be fixed is fixed;   a light source which illuminates an original surface;   a lens array which forms an image reflected from the original surface; and   a photoelectric conversion element which converts light from said lens array into an electrical signal.   
     
     
         10 . An image reading apparatus comprising an image sensor unit cited in  claim 9 . 
     
     
         11 . A thermal caulking method of caulking an object to be fixed by thermally deforming a caulking projection formed on a surface of a molded product made of a thermoplastic resin and having a substantially rectangular parallelepiped outer shape said method comprising the steps of
 fitting the object to be fixed in a frame of the molded product having, on the surface, a plurality of caulking projections substantially linearly arranged in a longitudinal direction of the molded product, and an antiwarping groove formed in a position apart from a proximal portion of each caulking projection; and   caulking the object to be fixed by deforming the caulking projection by heat and pressure.   
     
     
         12 . A thermal caulking method according to  claim 11 , wherein the position apart from the proximal portion is determined on the basis of shapes of a caulking jig for use in caulking manufacture and the caulking projection. 
     
     
         13 . A thermal caulking method according to  claim 11 , wherein the frame is formed to surround end faces of the object to be fixed, and the plurality of caulking projections are formed on an upper surface of the frame. 
     
     
         14 . A thermal caulking method according to  claim 11 , wherein the caulking projection is formed on a surface of the molded product, which is to be connected to the object to be fixed, and the caulking projection is caulked after being inserted through and protruded from a caulking hole formed in the object to be fixed. 
     
     
         15 . A thermal caulking method according to  claim 13 , wherein the caulking projection is deformed to be substantially leveled with an upper surface of the frame after caulking. 
     
     
         16 . A thermal caulking method according to  claim 11 , wherein the antiwarping groove has a structure which reduces heat conduction from the caulking projection to the molded product outside the antiwarping groove during caulking. 
     
     
         17 . A thermal caulking method according to  claim 11 , wherein the thermoplastic resin is polycarbonate.