Photodetector and display device with light guide configured to face photodetector circuit and reflect light from a source

A photodetector comprising:

• a substrate;
• photodetector circuits arranged in a matrix on the substrate;
• a display circuit on the substrate;
• a light unit comprising a light source, a light guide plate, and a fixing member;
• and
• a data processing circuit,
• wherein the light guide plate comprises a first face, a second face opposite to the first face, and a third face, and is configured to be in contact with an object at a part of the first face and to reflect a light emitted from the light source at the part where the object contacts the first face,
• wherein the second face of the light guide plate is configured to face the photodetector circuits,
• wherein the fixing member is configured to fix the light source to the third face of the light guide plate and to overlap with the light source and a portion of the light guide plate, and
• wherein each of the photodetector circuits is configured to generate a data signal from the light reflected at the part.

A photodetector comprising:

• a substrate;
• display circuits arranged in a matrix on the substrate;
• photodetector circuits arranged in a matrix on the substrate;
• a light unit comprising a light source, a light guide plate, and a fixing member;
• and
• a data processing circuit,
• wherein each of the display circuits and each of the photodetector circuits are arranged periodically on a face of the substrate,
• wherein the light guide plate comprises a first face, a second face opposite to the first face, and a third face, and is configured to be in contact with an object at a part of the first face and to reflect a light emitted from the light source at the part where the object contacts the first face,
• wherein the second face of the light guide plate is configured to face the photodetector circuits,
• wherein the fixing member is configured to fix the light source to the third face of the light guide plate and to overlap with the light source and a portion of the light guide plate, and
• wherein each of the photodetector circuits generates a data signal from the light reflected at the part.