Solid state bidirectional light sheet for general illumination

A bidirectional lighting device comprising:

• a reflective substrate having a first surface and a second surface opposing the first surface;
• a plurality of non-packaged light emitting dies having electrodes;
• a first transparent substrate sandwiching a first subset of the plurality of dies between the first surface of the reflective substrate and the first transparent substrate, an outer surface of the first transparent substrate forming a first light emitting surface of the bidirectional lighting device through which light is emitted from the bidirectional lighting device in a first direction;
• a second transparent substrate sandwiching a second subset of the plurality of dies between the second surface of the reflective substrate and the second transparent substrate, an outer surface of the second transparent substrate forming a second light emitting surface of the bidirectional lighting device through which light is emitted from the bidirectional lighting device in a second direction opposing the first direction;
• first and second conductors formed on the respective first and second surfaces of the reflective substrate connected to the electrodes of the respective first and second sets of light emitting dies without wires for connecting the plurality of light emitting dies to a source of power;
• a first intermediate sheet between the first and reflective substrates, the first intermediate sheet having holes corresponding to locations of the dies of the first set on the first surface of the reflective substrate, such that each of the first set of dies is surrounded by walls of an associated hole of the first intermediate sheet;
• and
• a second intermediate sheet between the second and reflective substrates, the second intermediate sheet having holes corresponding to locations of the dies of the second set on the second surface of the reflective substrate, such that each of the second set of dies is surrounded by walls of an associated hole of the second intermediate sheet,
• wherein
• each die of the first set has a primary light output surface facing the first light emitting surface of the bidirectional lighting device, and each die of the second set has the primary light output surface facing the second light emitting surface of the bidirectional lighting device, wherein each die of the first and second sets have side walls perpendicular to the primary light output surface,
• the electrodes of the first set of dies are electrically connected to the first conductors on the first surface of the reflective substrate without wire bonds, and the electrodes of the second set of dies are electrically connected to the second conductors on the second surface of the reflective substrate without wire bonds,
• the first intermediate sheet has a first plurality of prisms on a surface of the first intermediate sheet adjacent to the reflective substrate to reflect light emitted through side walls of the first set of dies, the light reflected by the first plurality of prisms being directed in the first direction and output from the bidirectional lighting device through the first light emitting surface, and
• the second intermediate sheet has a second plurality of prisms on a surface of the second intermediate sheet adjacent to the reflective substrate to reflect light emitted through side walls of the second set of dies, the light reflected by the second plurality of prisms being directed in the second direction and output from the bidirectional lighting device through the second light emitting surface.