Abstract: A projection system includes a screen, a projection display apparatus for projecting a video image on the screen, and a mount base provided below a projection surface of the screen, for carrying a subject on its upper surface. The projection display apparatus is mechanically coupled to the screen such that video image light from the projection display apparatus is displayed on the screen. Projection display apparatus includes a light source, an imaging portion including the upper surface of the mount base at least in an imaging area, a light modulation portion for modulating light from the light source to generate the video image light based on an input video image or a video image picked up by the imaging portion, and a projection portion for projecting the video image light generated by the light modulation portion.

Abstract: A Y/C separation circuit includes a glass delay line for delaying an input composite video signal. A luminance signal and a chrominance signal are separated from each other by an adding circuit and a subtracting circuit each of which receives the input signal and an output signal from the glass delay line. The output signal from the glass delay line is phase-shifted by a 90.degree. phase shifting circuit and then inputted to a multiplier which further receives the input signal. The multiplier outputs an error signal according to a phase difference between color burst signals included in the both signals, and a control voltage according to the error signal is outputted from a low-pass filter. The control voltage is applied to gyrators which terminate an input and an output of the glass delay line, respectively, whereby an inductance value of each of the gyrators is controlled by the control voltage such that a delay time of the glass delay line can be exactly adjusted at one horizontal period.

Abstract: A frequency of a chrominance signal including a jitter component and separated from a color video signal is converted from a first frequency to a second frequency by first frequency converting device. Then, the chrominance signal which frequency is converted to the second frequency is converted to have the original frequency by second frequency converting device. Each of the first frequency converting device and the second frequency converting device includes a multiplier and a bandpass filter. One multiplier of the first and the second frequency converting devices and receives a frequency signal corresponding to a phase difference between a reference frequency signal and a color burst signal separated from the chrominance signal. As a result, the jitter component is removed from the chrominance signal either in the first or the second frequency converting.