Projection display device and method of controlling projection display device

A projection display device comprising:

• a re-entry illumination light intensity calculation unit configured, for each pixel constituting a target frame for analyzing a video among frames in video data to be displayed on a reflective liquid crystal display element, to calculate an intensity of re-entry illumination light, which is a first polarized light that, among first polarized lights of illumination light including first and second polarized lights entering the reflective liquid crystal display element via a polarizing plate, is reflected without being modulated by the reflective liquid crystal display element and returns to a light source unit side of the polarizing plate, is reflected by an optical element located on the light source unit side of the polarizing plate or by the light source unit, and re-enters the reflective liquid crystal display element via the polarizing plate, and to calculate a summed value obtained by summing the intensity of the re-entry illumination light calculated for all pixels constituting the target frame;
• a reference re-entry illumination light intensity storage unit configured to store a reference summed value obtained by summing the intensity of the re-entry illumination light at all pixels when reference frame images from a minimum gray level to a maximum gray level are displayed on the reflective liquid crystal display element;
• and
• a light source control unit configured to control a light emission amount from a light source included in the light source unit by selecting a reference summed value corresponding to any one of the reference frame images based on the target frame, and comparing the summed value calculated by the re-entry illumination light intensity calculation unit with the selected reference summed value.