Light source device and liquid crystal display device

Abstract

In a backlight device ( 2 ), a substrate ( 21 ) on which LEDs ( 22 ) are mounted is fixed to a bottom section ( 32 ) of a case ( 31 ) from the outside of the case ( 31 ) with the LEDs ( 22 ) fitted in openings ( 32 a ) in the bottom section ( 32 ) of the case ( 31 ). As a result, that face of the rear surface of the substrate ( 21 ) which excludes a portion on which driver circuits ( 23 ) are mounted is in contact with outside air, and this allows heat generated by the LEDs ( 22 ) to be dissipated to the outside air through the substrate ( 21 ). Thus, the backlight device ( 2 ) can dissipate the heat of the LEDs ( 22 ) without requiring a conventional heat dissipating mechanism (heat dissipating plate, heat pipe, heat sink, and cooling fan) constituted with a large number of parts to be mounted below the LEDs ( 22 ). As a result, the backlight device ( 2 ) is reduced in thickness, weight, and cost, with a reduction in light-emitting efficiency of the LEDs ( 22 ) minimized.

1 . A light source device, comprising:
 a substrate having a surface on which a light-emitting diode is mounted; and   a case holding said substrate,   wherein a driver circuit for driving said light-emitting diode is mounted on a rear surface of said substrate,   wherein an opening corresponding to a size of said light-emitting diode is formed in a bottom section of said case, and   wherein said substrate is fixed to the bottom section of said case from outside of said case with said light-emitting diode fitted in said opening.   
     
     
         2 . The light source device according to  claim 1 , further comprising a heat conductive sheet that conducts heat of said light-emitting diode,
 wherein said substrate is fixed to the bottom section of said case through said heat conductive sheet.   
     
     
         3 . The light source device according to  claim 1 , further comprising a reflective sheet for reflecting incident light,
 wherein said reflective sheet includes a hole that is formed in a position corresponding to a light-emitting part of said light-emitting diode, and the reflective sheet is formed in the bottom section of said case on a surface opposite to a side to which said substrate is fixed so as to cover an entire region of the surface except for said light-emitting part.   
     
     
         4 . The light source device according to  claim 1 , wherein an outer surface of four side walls constituting an outer frame that is perpendicular to the bottom section of said case is a rough surface having recesses and projections. 
     
     
         5 . The light source device according to  claim 1 , wherein a coating material with an emissivity of equal to or higher than 0.9 and equal to or lower than 1.0 is applied to an outer surface of four side walls constituting an outer frame that is perpendicular to the bottom section of said case. 
     
     
         6 . The light source device according to  claim 1 , wherein the bottom section of said case as well as four side walls constituting an outer frame that is perpendicular to said bottom section are formed of aluminum alloy. 
     
     
         7 . The light source device according to  claim 1 , wherein there are a plurality of said light-emitting diodes, and said light-emitting diodes are disposed in a zigzag arrangement on a surface of said substrate. 
     
     
         8 . The light source device according to  claim 1 , wherein a formation pitch of the opening in the bottom section of said case is equivalent to an arrangement pitch of said light-emitting diode mounted on the surface of said substrate. 
     
     
         9 . The light source device according to  claim 1 , wherein said driver circuit is mounted on a rear surface of said substrate in a position corresponding to an area in which said light-emitting diodes is absent. 
     
     
         10 . A liquid crystal display device, comprising:
 the light source device according to  claim 1 ; and   a liquid crystal panel on which light is emitted by said light source device.