Light-emitting unit and illumination device and image reading device using light-emitting unit

Abstract

A light-emitting unit 20 has a light-emitting unit board 21 made of resin provided with a lead frame 22. The light-emitting unit board 21 is also provided with an open window 21 a for mounting a light-emitting device. The lead frame 22 comprises a lead terminal section 22 a, an inner lead section 22 c, and a light-emitting device mounting and connecting section 22 b which is exposed within the open window 21 a. The light-emitting devices 23 a, 23 b, and 23 c are bonded with the light-emitting device mounting and connecting section 22 b, and electrodes of the light-emitting devices and the lead frame are connected by a metal wire 24, wherein the open window 21 a is sealed by transparent resin. The lead frame 22 is made of iron-containing copper to improve heat radiation performance of the light-emitting unit board. By increasing maximum current to be supplied to the light-emitting diodes, it is possible to increase illumination brightness and to attain speedup of image reading.

1 . A light-emitting unit having a light-emitting device mounted on a light-emitting unit board which is provided with a lead frame, wherein the lead frame is made of a copper alloy or an aluminum alloy of which the heat conductivity is 250 W/(m·K) or more.  
   
   
       2 . The light-emitting unit according to  claim 1 , wherein the copper alloy is iron-containing copper having composition of Fe: 0.02 ˜ 0.5 wt %; P: 0.005 ˜ 0.10 wt %; and the rest: Cu  
   
   
       3 . A light-emitting unit having a light-emitting device mounted on a light-emitting unit board which is provided with a lead frame, wherein the light-emitting unit board is made of resin of which the heat resistant temperature is higher than a melting point of lead-free solder which is used when the lead frame is soldered onto an electric circuit.  
   
   
       4 . The light-emitting unit according to  claim 3 , wherein the resin is polyphthalamide resin, polyphenylene sulfide resin, or liquid crystal polymer.  
   
   
       5 . An illumination device designed to emit light incident from a light-emitting unit which is provided on an end face of a bar-shaped light guide in the longitudinal direction from a light-emitting surface provided along the longitudinal direction while reflecting the light by the inner surface of the bar-shaped light guide, wherein the light-emitting unit is specified by  claim 1 .  
   
   
       6 . An illumination device designed to emit light incident from a light-emitting unit which is provided on a side of a plate-shaped light guide in the direction of the thickness from the upper or lower surface of the plate-shaped light guide while reflecting the light by the inner surface of the plate-shaped light guide, wherein the light-emitting unit is specified by  claim 1 .  
   
   
       7 . An image reading device comprising the illumination device according to  claim 5 , a line image sensor, and a rod lens array for converging the reflected light or transmitted light from a document on the line image sensor, wherein each of them is incorporated within a frame.  
   
   
       8 . An image reading device comprising the illumination device according to  claim 6 , a line image sensor, and a rod lens array for converging the reflected light or transmitted light from a document on the line image sensor, wherein each of them is incorporated within a frame.  
   
   
       9 . An illumination device designed to emit light incident from a light-emitting unit which is provided on an end face of a bar-shaped light guide in the longitudinal direction from a light-emitting surface provided along the longitudinal direction while reflecting the light by the inner surface of the bar-shaped light guide, wherein the light-emitting unit is specified by  claim 3 .  
   
   
       10 . An illumination device designed to emit light incident from a light-emitting unit which is provided on a side of a plate-shaped light guide in the direction of the thickness from the upper or lower surface of the plate-shaped light guide while reflecting the light by the inner surface of the plate-shaped light guide, wherein the light-emitting unit is specified by  claim 3.