Phase plate and fabrication method for color-separated laser backlight in display systems
According to examples, a phase plate may include a transparent substrate and a photopolymer layer attached to the transparent substrate. The photopolymer layer may adjust a backlight via a phase adjustment and focusing. The phase plate may focus a plurality of red, green, and blue components of the backlight onto respective red, green, and blue subpixels of a thin-film-transistor (TFT) layer deposited thereon. A distance between the photopolymer layer of the phase plate and the plurality of red, green, and blue subpixels of the thin-film-transistor (TFT) layer may be in a range from about 200 μm to about 500 μm. In some examples, the phase plate may be part of a liquid crystal display (LCD) apparatus along with a red, green, blue (RGB) laser to provide backlight; a grating light guide to transmit the backlight; and a liquid crystal display (LCD) layer on the thin-film-transistor (TFT) layer.
1. A liquid crystal display (LCD) apparatus, comprising:
a red, green, blue (RGB) laser to provide backlight;
a grating light guide to transmit the backlight;
a phase plate comprising a transparent substrate and a photopolymer layer to adjust the backlight via a phase adjustment and focusing;
a thin-film-transistor (TFT) layer on the phase plate, wherein the phase plate is to focus a plurality of red, green, and blue components of the backlight onto respective red, green, and blue subpixels of the thin-film-transistor (TFT) layer; and
a liquid crystal display (LCD) layer on the thin-film-transistor (TFT) layer.
2. The liquid crystal display (LCD) apparatus of claim 1 , further comprising at least one or more of:
a first polarizer layer between the phase plate and the thin-film-transistor (TFT) layer;
a color filter on the liquid crystal display (LCD) layer; or
a second polarizer layer on the color filter.
3. The liquid crystal display (LCD) apparatus of claim 1 , wherein the phase plate is to focus the plurality of red, green, and blue components of the backlight onto the respective red, green, and blue subpixels of the thin-film-transistor (TFT) layer to cause each of the plurality of red, green, and blue subpixels transmit light at a full width at half maximum (FWHM) cone angle of about 40 degrees.
4. The liquid crystal display (LCD) apparatus of claim 1 , wherein each of the plurality of red, green, and blue subpixels has a width in a range from about 2 micrometers to about 5 micrometers, and each pixel has a width in a range from about 10 micrometers to about 25 micrometers.
5. The liquid crystal display (LCD) apparatus of claim 1 , wherein the photopolymer layer of the phase plate has a thickness that is in a range from about 3 micrometers to about 50 micrometers.
6. The liquid crystal display (LCD) apparatus of claim 1 , wherein the photopolymer layer of the phase plate is fabricated via an exposure technique that exposes the photopolymer layer to a collimated laser light.
7. The liquid crystal display (LCD) apparatus of claim 6 , wherein a thickness of the photopolymer layer is selected, at least in part, based on the exposure technique.
8. The liquid crystal display (LCD) apparatus of claim 1 , wherein a distance between the photopolymer layer of the phase plate and the plurality of red, green, and blue subpixels of the thin-film-transistor (TFT) layer is in a range from about 200 micrometers to about 500 micrometers.
9. The liquid crystal display (LCD) apparatus of claim 1 , wherein photopolymer layer is fabricated by exposure to a collimated laser light through an exposure mask.
10. The liquid crystal display (LCD) apparatus of claim 9 , wherein
the collimated laser light is passed through at least one of the exposure mask itself to create a collimated beam or a plurality of pinholes to create a spherical wavefront.
11. The liquid crystal display (LCD) apparatus of claim 9 , wherein
a surface of the exposure mask is covered with 1% chrome, or
a size of the exposure mask is in a range from about 5 cm×5 cm to about 8 cm×8 cm.
12. The liquid crystal display (LCD) apparatus of claim 9 , wherein the photopolymer layer comprises a plurality of films and is fabricated by:
exposure of each film to the collimated laser light through the exposure mask; and
lamination of each film on another exposed film.