Beam steering backlight unit and holographic display apparatus including the same

A holographic display apparatus comprising:

• a spatial light modulator configured to reproduce a hologram image by diffracting incident light;
• a backlight unit configured to provide light to the spatial light modulator;
• and
• a field lens configured to focus the hologram image reproduced by the spatial light modulator on a predetermined space,
• wherein the backlight unit comprises:
• a light source array comprising a plurality of two-dimensionally arranged light sources;
• a micro lens array comprising a plurality of two-dimensionally arranged micro lenses;
• and
• a controller configured to control the plurality of light sources,
• wherein the light source array comprises a plurality of light source blocks, wherein each of the plurality of light source blocks respectively corresponds to one of the plurality of micro lenses, and wherein each of the plurality of light source blocks comprises a plurality of the light sources,
• wherein the light source array is configured such that each of the plurality of light sources arranged in each of the plurality of light source blocks is independently driven,
• wherein the controller is configured to select and turn on only a subset of light sources and turn off light sources other than the subset of light sources, wherein each of the subset of light sources is disposed at a same respective position within each of the plurality of light source blocks, and
• wherein a location of the hologram image reproduced by the spatial light modulator on the predetermined space varies depending on the respective position of the light sources of the subset in each of the plurality of light source blocks.

A heads-up display apparatus comprising:

• a spatial light modulator configured to reproduce an image by diffracting incident light;
• a backlight unit configured to provide light to the spatial light modulator;
• a field lens configured to focus an image reproduced by the spatial light modulator on a predetermined space;
• and
• an eye tracker configured to track locations of an observer's pupils,
• wherein the backlight unit comprises:
• a light source array comprising a plurality of two-dimensionally arranged light sources;
• a micro lens array comprising a plurality of two-dimensionally arranged micro lenses;
• and
• a controller configured to control the plurality of light sources,
• wherein the light source array comprises a plurality of light source blocks, wherein each of the plurality of light source blocks respectively corresponds to one of the plurality of micro lenses, and wherein each of the plurality of light source blocks comprises a plurality of the light sources,
• wherein the light source array is configured such that each of the plurality of light sources arranged in each of the plurality of light source blocks if independently driven,
• wherein the controller is configured to select and turn on only a subset of light sources and turn off light sources other than the subset of light sources, wherein each of the subset of light sources is disposed at a same respective position within each of the plurality of light source blocks,
• wherein a location of the image reproduced by the spatial light modulator on the predetermined space varies depending on the respective positions of the light sources of the subset, and
• wherein the controller selects the respective positions of the light sources of the subset in order to provide the image to the locations of the observer's pupils received from the eye tracker.