Backlight for liquid crystal devices

An LCD lighting system including an LCD element, said system being compatible with night vision equipment comprising:

• a generally rectangular block consisting of a transparent material, said block having
• a top display surface having a recess that increases in depth toward a center of said block;
• two end surfaces opposite each other and adjacent to an edge of said top display surface wherein said recess is at a minimum;
• first light source means capable of emitting a full spectrum of visible light, said first light source means being adjacent a surface such that light from said first light source means enters said block through said surface and is emitted through said display surface;
• second light source means including selecting means to limit the emission of infrared and near infrared light, said second light source means being adjacent to at least one of said end surfaces such that light from said second light source means enters said block through an end surface and is emitted through said display surface;
• means for disabling said first light source means during night viewing;
• and
• light diffusion means between said rectangular block and the LCD for diffusing light emitting from said block before reaching the LCD display.

An LCD lighting system compatible with night vision equipment comprising:

• a back lit LCD display element;
• first and second truncated, wedge-shaped blocks of light transmitting material, said block having a planar display surface and a planar under surface which converge at an acute optimum angle, said block having an end surface at said truncation;
• and
• first light source means including selecting means for limiting the emission of infrared and near infrared light, said first light source means being adjacent to said end surface of said first block such that light from said first light source means enters said first block through said end surface of said first block, said acute angle of said first block being chosen to optimize the amount and quality of light from said first light source means emitted from said planar display surface of said first block;
• second light source means capable of emitting a full spectrum of visible light, said second light source means being adjacent to said end surface of said second block such that light from said second light source means enters said second block through said end surface of said second block, said acute angle of said second block being chosen to optimize the amount and quality of light from said second light source means emitted from said planar display surface of said second block;
• and
• reflective means adjacent to said planar under surface of said second wedge-shaped block,
• said first and second wedge-shaped blocks being arranged so that light from said first and second light sources is able to emit from said emission surface of said first block.

An LCD lighting system compatible with day and night vision equipment comprising:

• a block of light transmitting material, having a display surface and an under surface and an end surface;
• a first light source, capable of emitting full spectrum visible light, said first light source being adjacent to said under surface such that light from said first light source enters said block through said under surface;
• a second light source, including selecting means for limiting the emission of infrared light, said second light source being adjacent to said end surface such that light from said second light source enters said block through said end surface;
• and
• means for disabling said first light source during night viewing.