Abstract: An auto-iris method for an imaging device includes the steps of obtaining a first signal indicating brightness of an object from a signal output from an imaging element; comparing a level of the first signal with a level of a reference signal; and enhancing a level of the reference signal more as the object becomes brighter and controlling an iris to path more quantity of light to the imaging element, based on the compared result.

Abstract: A diversity reception apparatus which has a plurality of antennas and in which one of the antennas having the best receiving condition is automatically selected and connected to a broadcasting signal receiver. The diversity reception apparatus has a feature in that after demodulated signals, obtained by the receiver respectively corresponding to the plurality of antennas, are converted into digital signals by an A/D converter, the best demodulated signal and the antenna corresponding thereto are selected by comparing the digital signals with each other, and that the width of a switch driving pulse from a switch driving pulse generator is made not more than 3 .mu.s.

Abstract: A time-dividing circuit including a first capacitor, a second capacitor, a current source for charging the first capacitor, circuitry for distributing the charge of the first capacitor to the second capacitor in a predetermined ratio, a compare for comparing the voltages on the first and second capacitors and producing a comparison output signal, circuitry for discharging the charges on the first and second capacitors, and a control circuit for producing control signals for controlling the time-dividing circuit. The time-dividing circuit can be utilized in an automatic white balance control circuit for a color television receiver.

Abstract: A video signal processing circuit is provided to display an image of a standard television signal on a display unit with a 6:9 aspect ratio by enlarging an image of a video signal in the horizontal and vertical directions by a magnification factor which depends on the feature of the standard television signal. The processing circuit includes a first memory circuit which reads out the stored video signal in response to a read clock different from the write clock and generated by a stable frequency source so that the image of the video signal is expanded in the vertical direction, a second memory circuit which implements time-base compression for the output of the first memory circuit and thereafter expands the signal, a spatial filter which implements filtering for the output of the second memory circuit, an enlargement control circuit which control the above-mentioned circuits, and a synchronizing processing circuit.

Abstract: An image control apparatus includes a waveform equalizer, a distorted waveform extraction control unit, a noise reduction circuit, and an image quality control unit. The waveform equalizer receives an input video signal, equalizes the waveform of the video signal, and outputs the waveform equalized video signal. The distorted waveform extraction control unit detects a distorted waveform from the output of the waveform equalizer and controls the waveform equalizer to perform waveform equalization suitable for the input video signal.

Abstract: A gradation conversion system comprising: a plurality of gradation conversion devices for converting color display data into gradation display data by different gradation conversion methods, respectively; and switching device for selectively activating one of the plurality of graduation conversion device. Accordingly, if a number of different colors are to be displayed in the same number of gradations when converting multi-color display data into gradation display data, it is possible to perform this gradation conversion. On the other hand, if different colors are to be displayed in gradations as exact to the brightnesses of colors as possible, it is possible to select one of plural gradation conversion methods so as to carry out this gradation conversion.

Abstract: There is provided the construction of a multiprojection apparatus composed of a plurality of projection units arranged in the vertical and horizontal directions, in which a transparent holding strip having an H-shaped cross section is inserted between screens each composed of a lenticular sheet and a Fresnel lens, and the right and left ends of a multiscreen are supported by elastic support members, or in which a receive member for receiving the screen in the direction of the optical axis and a screen holding device are provided, the receive member has such a shape as not to block projection light corresponding to an image on the screen and is located near a joint of the screen and another screen, and the holding device is disposed on a black stripe of the lenticular sheet and always pulled by an elastic member toward the receive member. Therefore, according to the present invention, it is possible to restrict the missing of information due to joints of the screens.

Abstract: The object of the invention is to provide a large-screen projection-type display using a transmission-type screen, wherein the transmission-type screen is formed of two or more sheets 4, 7, is tilted toward the viewer's side with a small gap kept between the sheets, and is stable relative to the temperature and moisture change of the environment. The front sheet 4 provided on the viewer's side and the Fresnel sheet 7 provided on the projection source side are tilted forward by about 7.degree. toward the viewers. The springs 10 are extended through wires 9 to exert the tension on the front sheet 4 in the vertical direction. At the same time, the springs exert a pressure on the Fresnel sheet 7 in the vertical direction.

Abstract: A phase locked loop IC comprising a voltage controlled oscillator which generates a clock signal in accordance with a control voltage, a first ECL input buffer which is an input buffer for a signal to be synchronized, a phase-lock capture circuit for producing a current determinative of the control voltage in accordance with the phase difference and the frequency difference between the signal to be synchronized and the clock signal, and a phase-lock follow-up circuit for producing a current determinative of the control voltage in accordance with the phase difference between the clock signal and the signal to be synchronized; wherein the supply voltage system of the first ECL input buffer is so disposed as to be isolated from any of the supply voltage systems of the voltage-controlled oscillator, the phase-lock capture circuit and the phase lock follow-up circuit, while the ground system of the first ECL input buffer is so disposed as to be insolated from any of the ground systems of the voltage-controlled osc