PURPOSE: To enable appropriate correction of variation in light quantity to be constantly performed irrespective of changes with time or the like, by reading correction range data and energization time data from a memory according to the quantity of light emitted from LED elements corresponding to an image signal, and supplying the LED element with an image signal based on the data.

CONSTITUTION: An LED array 16 comprises a plurality of LED elements arranged in an array. A memory 15 stores correction range data obtained by dividing an estimated quantity of light emitted from the LED elements for each predetermined range, and energization time data calculated in accordance with the correction range data. A driving circuit 14 takes out the correction range data and the energization time data from the memory 15 according to the quantity of light emitted from the LED elements. Based on the correction range data and the energization time data thus taken out, an image signal is supplied to the corresponding LED elements, thereby driving the LED elements to emit light. Accordingly, correction of variation in light quantity can be performed within an arbitrary correction range, so that optimum correction of variation in light quantity can be constantly performed irrespective of changes with time.