Lighting device and projection display apparatus

Abstract

A lighting device of the present disclosure includes an excitation light source, a phosphor, a spreader, a reflective layer, and a reflective region. The excitation light source emits a polarized light. The phosphor receives the light as an excitation light from the excitation light source, and emits a fluorescent light, the phosphor including a plurality of phosphor pieces adjacently disposed on the reflective layer, the plurality of phosphor pieces having a same characteristic. The spreader supports the phosphor. The reflective layer is disposed between the phosphor and the spreader, and reflects the fluorescent light. The reflective region is disposed between the plurality of phosphor pieces, the reflective region reflecting the received excitation light while keeping a polarization characteristic of the received excitation light.

What is claimed is: 
     
         1 . A lighting device comprising:
 an excitation light source configured to emit a polarized light;   a phosphor configured to receive the polarized light as an excitation light from the excitation light source, and emit a fluorescent light, the phosphor including a plurality of phosphor pieces adjacently disposed on the reflective layer, the plurality of phosphor pieces having a same characteristic;   a spreader configured to support the phosphor;   a reflective layer disposed between the phosphor and the spreader, and configured to reflect the fluorescent light; and   a reflective region disposed between the plurality of phosphor pieces, the reflective region reflecting the received excitation light while keeping a polarization characteristic of the received excitation light.   
     
     
         2 . The lighting device according to  claim 1 , further comprising, between the excitation light source and the phosphor:
 an afocal optical system configured to convert the excitation light received from the excitation light source into collimated light;   a diffuser panel configured to diffuse the received excitation light while keeping the polarization characteristic;   a dichroic mirror disposed obliquely with respect to the received excitation light, and configured to reflect an S-polarized light of a waveform of the excitation light source and transmit a P-polarized light of the waveform of the excitation light source;   a quarter wavelength plate configured to receive the excitation light from the excitation light source; and   a condenser lens configured to collect the received excitation light onto the phosphor to form a spot.   
     
     
         3 . The lighting device according to  claim 1 , the light device further comprises:
 an adhesive layer disposed between the reflective layer and the spreader,   wherein   the reflective layer is disposed on a face of the phosphor.   
     
     
         4 . The lighting device according to  claim 1 , the light device further comprises:
 a light-transmitting adhesive layer is disposed between the phosphor and the reflective layer,   wherein   the reflective layer is disposed on a face of the spreader.   
     
     
         5 . The lighting device according to  claim 4 , wherein
 the reflective layer includes a reflective material in a light-transmitting adhesive material.   
     
     
         6 . The lighting device according to  claim 1 , wherein
 the phosphor includes an inorganic material.   
     
     
         7 . The lighting device according to  claim 6 , wherein
 the phosphor includes a ceramic plate including the inorganic material.   
     
     
         8 . The lighting device according to  claim 1 , wherein
 the spreader includes one of an aluminum material, a copper material, and a silicon carbide.   
     
     
         9 . The lighting device according to  claim 1 , wherein
 the excitation light source includes a blue laser, and the phosphor receives the excitation light and emits an yellow light.   
     
     
         10 . The lighting device according to  claim 1 , wherein
 the phosphor is fixed to the spreader via the reflective layer by diffusion bonding.   
     
     
         11 . The lighting device according to  claim 1 , wherein
 the spreader is fixed, and includes a cooling means inside the spreader or on a surface of the spreader, the phosphor being not on the surface.   
     
     
         12 . The lighting device according to  claim 1 , wherein
 a reflective surface of the reflective region configured to receive the excitation light has an uneven shape.   
     
     
         13 . The lighting device according to  claim 1 , wherein
 the reflective region includes:
 a light-transmitting member; and 
 the reflective layer disposed between the light-transmitting member and the spreader. 
   
     
     
         14 . The lighting device according to  claim 1 , wherein
 a reflective surface of the reflective region configured to receive the excitation light has a fine uneven portion on a projecting or recessed reference surface.   
     
     
         15 . The lighting device according to  claim 1 , wherein
 the reflective region includes a reflective surface configured to receive the excitation light,   the plurality of phosphor pieces include phosphor surfaces configured to receive the excitation light, and   an area ratio of the reflective surface to the phosphor surfaces is 10-20 to 100.   
     
     
         16 . The lighting device according to  claim 1 , wherein
 the reflective region includes a reflective surface configured to receive the excitation light,   the plurality of phosphor pieces include phosphor surfaces configured to receive the excitation light, and   when an area change rate of an effective range of the excitation light received by the phosphor is ±20% or less, a change rate of an area ratio of the reflective surface to the phosphor surfaces in the effective range is a half or less of the area change rate.   
     
     
         17 . The lighting device according to  claim 2 , wherein
 the quarter wavelength plate is disposed so that the polarized light perpendicularly enters the quarter wavelength plate, and   an angle of a phase axis with respect to a polarization axis of the polarized light is adjustable.   
     
     
         18 . The lighting device according to  claim 2 , wherein
 a distance from the phosphor to the condenser lens is adjustable.   
     
     
         19 . A projection display apparatus comprising:
 the lighting device according to  claim 1 ;   an image display element configured to modulate a light outgoing from the lighting device in response to a image signal, and generate an image light; and   a projection lens configured to enlarge and project the image light generated by the image display element.