Manufacturing method for light guide plate

A method for manufacturing a light guide plate for guiding light that enters the light guide plate from a side surface of the light guide plate to output the light from two major surfaces of the light guide plate that are opposite each other, the method comprising:

• arranging fabrication dots in a matrix shape at a rectangular, outer surface of an ultrasonic fabrication horn;
• and
• forming, on both of the two major surfaces of the light guide plate that are opposite each other, reflection dots corresponding to the fabrication dots by
• pressing said outer surface of the ultrasonic fabrication horn to said major surfaces to form a group of the reflection dots, and
• moving the ultrasonic fabrication horn with respect to the light guide plate in a movement that correlates to the pressing, to form the remainder of the reflection dots,
• a subset of the reflection dots each having a depth so that the depths of respective reflection dots of the subset of the reflection dots increase in a stepwise manner as a distance of the respective reflection dots of the subset of the reflection dots from a light source increases.