Abstract: When gradation of a mixed video signal is equal to or less than a predetermined gradation, a subframe data generator generates subframe data so that an applied voltage to a display element is turned off during a first predetermined period from a start of the frame of a video signal for a visible light image or a video signal for an infrared light image. A light source controller turns on a visible light source after a lapse of a second predetermined period from a start of the frame of the video signal for a visible light image, and turns off the visible light source at the timing when the frame of the video signal for a visible light image is ended.

Abstract: When gradation of a mixed video signal is equal to or less than a predetermined gradation, a subframe data generator generates subframe data so that an applied voltage to a display element is turned off during a first predetermined period from a start of the frame of a video signal for a visible light image or a video signal for an infrared light image. A light source controller turns on a visible light source after a lapse of a second predetermined period from a start of the frame of the video signal for a visible light image, and turns off the visible light source at the timing when the frame of the video signal for a visible light image is ended.

Abstract: Data pieces representative of in-phase components and quadrature components of a digital-modulation-resultant signal are assigned to frequencies for inverse fast Fourier transform. The inverse fast Fourier transform is executed at a predetermined sampling frequency Fs to convert the data pieces into a real-part signal and an imaginary-part signal. Phases of the real-part signal and the imaginary-part signal are shifted. Each of the phase-shifted real-part signal and the phase-shifted imaginary-part signal is divided into a sequence of even-numbered samples and a sequence of odd-numbered samples. A digital quadrature-modulation-resultant signal is generated from further manipulation of the even-numbered and odd-numbered samples.

Abstract: A first orthogonal-multi-carrier signal is generated through N-point inverse discrete Fourier transform. The first orthogonal-multi-carrier signal has “N” or less orthogonal multiple carriers, where “N” denotes a predetermined natural number equal to or greater than 2. Every 1-unit time segment of the first orthogonal-multi-carrier signal is repeated “M” times to generate every 1-symbol time segment of a second orthogonal-multi-carrier signal. The second orthogonal-multi-carrier signal has a thinned set of “N” or less orthogonal multiple carriers spaced at M-carrier intervals, where “M” denotes a predetermined natural number equal to or greater than 2.

Abstract: High-frequency components are extracted from an OFDM signal. A symbol clock signal is generated in response to the extracted high-frequency components. Specifically, a sample clock signal is generated in response to the OFDM signal. A frequency of the sample clock signal is divided to generate the symbol clock signal from the sample clock signal. A timing of the frequency division is controlled in response to the extracted high-frequency components.