Display unit and electronic apparatus

Abstract

The invention provides a display unit that displays images on both the front and the rear surfaces and that displays images brightly without increasing the electrical power consumption. A liquid crystal display unit includes two liquid crystal cells, a backlight, which is interposed between the two liquid crystal cells and which emits light to the liquid crystal cells, and two reflective polarizers interposed between the backlight and each of the liquid crystal cells, respectively.

1 . A display device comprising: 
 a first transmissive polarization axis rotating device;    a second transmissive polarization axis rotating device having a display area size that is smaller than a display area size of the first transmissive polarization axis rotating device;    an illumination device disposed between the first transmissive polarization axis rotating device and the second transmissive polarization axis rotating device, the illumination device having a larger area in plan view than the display area of the first transmissive polarization axis rotating device, the illumination device being capable of illuminating the display area of the first transmissive polarization axis rotating device and the display area of the second transmissive polarization axis rotating device;    a reflective polarized light selecting device disposed between the illumination device and the second transmissive polarization axis rotating device; and    a light shielding layer interposed between the second transmissive polarization axis rotating device and the illumination device, the light shielding layer including an opening that enables the display area of the second transmissive polarization axis rotating device to be a light transmissive region.    
   
   
       2 . The display device according to  claim 1 , the light shielding layer being disposed on both sides of the opening with respect to a cross-sectional view of the display device.  
   
   
       3 . The display device according to  claim 1 , further comprising an absorptive polarized light selecting device disposed between the reflective polarized light selecting device and the second transmissive polarization axis rotating device, the absorptive polarized light selecting device absorbing light linearly polarized in one direction and transmitting light linearly polarized in direction that intersects the one direction.  
   
   
       4 . The display device according to  claim 1 , further comprising: 
 a scattering layer disposed between the illumination device and either the first transmissive polarization axis rotating device or the second transmissive polarization axis rotating device.    
   
   
       5 . The display device according to  claim 1 , the illumination device including: 
 a light source; and    a light guiding plate that guides light from the light source, the light guiding plate having a birefringence of about zero.    
   
   
       6 . The display device according to  claim 1 , the illumination device including an organic EL light that emits light from two opposite surfaces to radiate a surface of the first transmissive polarization axis rotating device and a surface of the second transmissive polarization axis rotating device with light.  
   
   
       7 . A foldable cellular phone, comprising: 
 the display device according to  claim 1;  and    a body paired with the display device.    
   
   
       8 . An electronic device comprising the display device according to  claim 1 .  
   
   
       9 . A display device comprising: 
 a first transmissive polarization axis rotating device;    a second transmissive polarization axis rotating device having a display area size that is smaller than a display area size of the first transmissive polarization axis rotating device;    an illumination device disposed between the first transmissive polarization axis rotating device and the second transmissive polarization axis rotating device, the illumination device having a larger area in plan view than the display area of the first transmissive polarization axis rotating device, the illumination device being capable of illuminating the display area of the first transmissive polarization axis rotating device and the display area of the second transmissive polarization axis rotating device;    a reflective polarized light selecting device disposed between the illumination device and the first transmissive polarization axis rotating device; and    a light shielding layer interposed between the second transmissive polarization axis rotating device and the illumination device, the light shielding layer including an opening that enables the display area of the second transmissive polarization axis rotating device to be a light transmissive region.    
   
   
       10 . The display device according to  claim 9 , the light shielding layer being disposed on both sides of the opening with respect to a cross-sectional view of the display device.  
   
   
       11 . The display device according to  claim 9 , further comprising an absorptive polarized light selecting device disposed between the reflective polarized light selecting device and the first transmissive polarization axis rotating device, the absorptive polarized light selecting device absorbing light linearly polarized in one direction and transmitting light linearly polarized in a direction that intersects the one direction.  
   
   
       12 . The display device according to  claim 9 , further comprising: 
 a scattering layer disposed between the illumination device and either the first transmissive polarization axis rotating device or the second transmissive polarization axis rotating device.    
   
   
       13 . The display device according to  claim 9 , the illumination device including: 
 a light source; and    a light guiding plate that guides light from the light source, the light guiding plate having a birefringence of about zero.    
   
   
       14 . The display device according to  claim 9 , the illumination device including an organic EL light that emits light from two opposite surfaces to radiate a surface of the first transmissive polarization axis rotating device and a surface of the second transmissive polarization axis rotating device with light.  
   
   
       15 . A foldable cellular phone, comprising: 
 the display device according to  claim 9;  and    a body paired with the display device.    
   
   
       16 . An electronic device comprising the display device according to  claim 9 .  
   
   
       17 . A display device comprising: 
 a first transmissive polarization axis rotating device;    a second transmissive polarization axis rotating device having a display area size that is smaller than a display area size of the first transmissive polarization axis rotating device;    an illumination device disposed between the first transmissive polarization axis rotating device and the second transmissive polarization axis rotating device, the illumination device having a larger area in plan view than the display area of the first transmissive polarization axis rotating device, the illumination device being capable of illuminating the display area of the first transmissive polarization axis rotating device and the display area of the second transmissive polarization axis rotating device;    a first reflective polarized light selecting device disposed between the illumination device and the first transmissive polarization axis rotating device;    a second reflective polarized light selecting device disposed between the illumination device and the second transmissive polarization axis rotating device; and    a light shielding layer interposed between the second transmissive polarization axis rotating device and the illumination device, the light shielding layer including an opening that enables the display area of the second transmissive polarization axis rotating device to be a light transmissive region.    
   
   
       18 . The display device according to  claim 17 , the light shielding layer being disposed on both sides of the opening with respect to a cross-sectional view of the display device.  
   
   
       19 . The display device according to  claim 17 , the first reflective polarized light selecting device reflecting light linearly polarized in a first direction and transmitting light linearly polarized in a second direction intersecting the first direction, the second reflective polarized light selecting device reflecting light linearly polarized in a third direction that intersects the first direction and transmitting light linearly polarized in a fourth direction intersecting the third direction.  
   
   
       20 . The display device according to  claim 17 , further comprising: 
 a first absorptive polarized light selecting device disposed between the first reflective polarized light selecting device and the first transmissive polarization axis rotating device, the first absorptive polarized light selecting device absorbing light linearly polarized in a first direction and transmitting light linearly polarized in a second direction that intersects the one direction, the first absorptive polarized light selecting device and the first reflective polarized light selecting device being arranged to bring the transmissive polarization axis of the first absorptive polarized light selecting device and a transmissive polarization axis of the first reflective polarized light selecting device in parallel with each other; and    a second absorptive polarized light selecting device disposed between the second reflective polarized light selecting device and the second transmissive polarization axis rotating device, the first absorptive polarized light selecting device absorbing light linearly polarized in a third direction and transmitting light linearly polarized in a fourth direction that intersects the third direction,    the second absorptive polarized light selecting device and the second reflective polarized light selecting device being arranged to bring the transmissive polarization axis of the second absorptive polarized light selecting device and a transmissive polarization axis of the second reflective polarized light selecting device in parallel with each other.    
   
   
       21 . The display device according to  claim 17 , further comprising: 
 a scattering layer disposed between the illumination device and either the first transmissive polarization axis rotating device or the second transmissive polarization axis rotating device.    
   
   
       22 . The display device according to  claim 17 , the illumination device including: 
 a light source; and    a light guiding plate that guides light from the light source, the light guiding plate having a birefringence of about zero.    
   
   
       23 . The display device according to  claim 17 , the illumination device including an organic EL light that emits light from two opposite surfaces to radiate a surface of the first transmissive polarization axis rotating device and a surface of the second transmissive polarization axis rotating device with light.  
   
   
       24 . The display device according to  claim 17 , the illumination device including: 
 a light source; and    a light guiding plate that guides light from the light source, the light guiding plate having a birefringence of λ/2 and a slow axis that forms an angle of about 45° with a reflective polarization axis of the first reflective polarized light selecting device and with a reflective polarization axis of the second reflective polarized light selecting device.    
   
   
       25 . The display device according to  claim 17 , the first and second reflective polarized light selecting devices being composed of a cholesteric liquid crystal, the first and second reflective polarized light selecting devices reflecting circularly polarized light that rotates in one direction and transmitting circularly polarized light that rotates in the opposite direction, the first and second reflective polarized light selecting devices being set to reflect circularly polarized light that rotates in the same rotative direction.  
   
   
       26 . The display device according to  claim 25 , further comprising a λ/4 retardation film disposed: 
 between the first transmissive polarization axis rotating device and the first reflective polarized light selecting device; or    between the second transmissive polarization axis rotating device and the second reflective polarized light selecting device.    
   
   
       27 . A foldable cellular phone, comprising: 
 the display device according to  claim 17;  and    a body paired with the display device.    
   
   
       28 . An electronic device comprising the display device according to  claim 17 .  
   
   
       29 . A display device comprising: 
 a first liquid crystal panel;    a second liquid crystal panel having a display area size that is smaller than a display area size of the first liquid crystal panel;    an illumination device disposed between the first liquid crystal panel and the second liquid crystal panel, the illumination device having a larger area in plan view than the display area of the first liquid crystal panel, the illumination device being capable of illuminating the display area of the first liquid crystal panel and the display area of the second liquid crystal panel;    a reflective polarizer disposed between the illumination device and the second liquid crystal panel; and    a light shielding layer interposed between the second liquid crystal panel and the illumination device, the light shielding layer including an opening that enables the display area of the second liquid crystal panel to be a light transmissive region.    
   
   
       30 . The display device according to  claim 29 , the light shielding layer being disposed on both sides of the opening in cross-sectional view of the display device.  
   
   
       31 . The display device according to  claim 29 , further comprising an absorptive polarizer disposed between the reflective polarizer and the second liquid crystal panel, the absorptive polarizer absorbing light linearly polarized in one direction and transmitting light linearly polarized in direction that intersects the one direction.  
   
   
       32 . The display device according to  claim 29 , further comprising: 
 a scattering layer disposed between the illumination device and either the first liquid crystal panel or the second liquid crystal panel.    
   
   
       33 . The display device according to  claim 32 , the scattering layer is composed of a film with a roughened surface or an adhesive film with a light scattering function.  
   
   
       34 . The display device according to  claim 29 , the illumination device including: 
 a light source; and    a light guiding plate that guides light from the light source, the light guiding plate having a birefringence of about zero.    
   
   
       35 . The display device according to  claim 29 , the illumination device including an organic EL light that emits light from two opposite surfaces to radiate a surface of the first liquid crystal panel and a surface of the second liquid crystal panel with light.  
   
   
       36 . A foldable cellular phone, comprising: 
 the display device according to  claim 29;  and    a body paired with the display device.    
   
   
       37 . An electronic device comprising the display device according to  claim 29 .  
   
   
       38 . A display device comprising: 
 a first liquid crystal panel;    a second liquid crystal panel having a display area size that is smaller than a display area size of the first liquid crystal panel;    an illumination device disposed between the first liquid crystal panel and the second liquid crystal panel, the illumination device having a larger area in plan view than the display area of the first liquid crystal panel, the illumination device being capable of illuminating the display area of the first liquid crystal panel and the display area of the second liquid crystal panel;    a reflective polarizer disposed between the illumination device and the first liquid crystal panel; and    a light shielding layer interposed between the second liquid crystal panel and the illumination device, the light shielding layer including an opening that enables the display area of the second liquid crystal panel to be a light transmissive region.    
   
   
       39 . The display device according to  claim 38 , the light shielding layer being disposed on both sides of the opening in cross-sectional view of the display device.  
   
   
       40 . The display device according to  claim 38 , further comprising an absorptive polarizer disposed between the reflective polarizer and the first liquid crystal panel, the absorptive polarizer absorbing light linearly polarized in one direction and transmitting light linearly polarized in a direction that intersects the one direction.  
   
   
       41 . The display device according to  claim 38 , further comprising: 
 a scattering layer disposed between the illumination device and either the first liquid crystal panel or the second liquid crystal panel.    
   
   
       42 . The display device according to  claim 41 , the scattering layer is composed of a film with a roughened surface or an adhesive film with a light scattering function.  
   
   
       43 . The display device according to  claim 38 , the illumination device including: 
 a light source; and    a light guiding plate that guides light from the light source, the light guiding plate having a birefringence of about zero.    
   
   
       44 . The display device according to  claim 38 , the illumination device including an organic EL light that emits light from two opposite surfaces to radiate a surface of the first liquid crystal panel and a surface of the second liquid crystal panel with light.  
   
   
       45 . A foldable cellular phone, comprising: 
 the display device according to  claim 38;  and    a body paired with the display device.    
   
   
       46 . An electronic device comprising the display device according to  claim 38 .  
   
   
       47 . A display device comprising: 
 a first liquid crystal panel;    a second liquid crystal panel having a display area size that is smaller than a display area size of the first liquid crystal panel;    an illumination device disposed between the first liquid crystal panel and the second liquid crystal panel, the illumination device having a larger area in plan view than the display area of the first liquid crystal panel, the illumination device being capable of illuminating the display area of the first liquid crystal panel and the display area of the second liquid crystal panel;    a first reflective polarizer disposed between the illumination device and the first liquid crystal panel;    a second reflective polarizer disposed between the illumination device and the second liquid crystal panel; and    a light shielding layer interposed between the second liquid crystal panel and the illumination device, the light shielding layer including an opening that enables the display area of the second liquid crystal panel to be a light transmissive region.    
   
   
       48 . The display device according to  claim 47 , the light shielding layer being disposed on both sides of the opening in cross-sectional view of the display device.  
   
   
       49 . The display device according to  claim 47 , further comprising: 
 a first absorptive polarizer disposed between the first reflective polarizer and the first liquid crystal panel, the first absorptive polarizer absorbing light linearly polarized in a first direction and transmitting light linearly polarized in a second direction that intersects the one direction, the first absorptive polarizer and the first reflective polarizer being arranged to bring the transmissive polarization axis of the first absorptive polarizer and a transmissive polarization axis of the first reflective polarizer in parallel with each other; and    a second absorptive polarizer disposed between the second reflective polarizer and the second liquid crystal panel, the first absorptive polarizer absorbing light linearly polarized in a third direction and transmitting light linearly polarized in a fourth direction that intersects the third direction,    the second absorptive polarizer and the second reflective polarizer being arranged to bring the transmissive polarization axis of the second absorptive polarizer and a transmissive polarization axis of the second reflective polarizer in parallel with each other.    
   
   
       50 . The display device according to  claim 47 , further comprising: 
 a scattering layer disposed between the illumination device and either the first liquid crystal panel or the second liquid crystal panel.    
   
   
       51 . The display device according to  claim 50 , the scattering layer is composed of a film with a roughened surface or an adhesive film with a light scattering function.  
   
   
       52 . The display device according to  claim 47 , the illumination device including: 
 a light source; and    a light guiding plate that guides light from the light source, the light guiding plate having a birefringence of about zero.    
   
   
       53 . The display device according to  claim 47 , the illumination device including an organic EL light that emits light from two opposite surfaces to radiate a surface of the first liquid crystal panel and a surface of the second liquid crystal panel with light.  
   
   
       54 . A foldable cellular phone, comprising: 
 the display device according to  claim 47;  and    a body paired with the display device.    
   
   
       55 . An electronic device comprising the display device according to  claim 47.