Abstract: The present invention provides an automatic identification level control circuit, an identification level control method, an automatic identification phase control circuit, an identification phase control method, and an optical receiver, capable of stably setting an optimal identification level or identification phase. An automatic identification level control circuit of the present invention includes a coupling capacitor, an identification circuit, a level fluctuation detection circuit, an identification voltage control circuit, and a low-pass filter. The identification circuit includes limiter amplifiers and flip flops. The level fluctuation detection circuit includes exclusive OR circuits.

Abstract: A photo receiver branches a data signal obtained by photoelectric conversion and supplies the signal to a signal cutoff detector. Depending on the degree of an autocorrelation of a data signal obtained by an autocorrelation detector, the signal cutoff detector detects abnormality/normality. Depending on a level of a control signal to a VCO contained in a frequency phase-locked loop for use in clock generation, an out-of-synchronization detector makes determination of abnormality/normality. Outputs of both the detectors are ORed at an alarm processor and when at least one of the detectors detects abnormality, the detector generates an alarm.

Abstract: A heat transfer tube for an absorber, including a plurality of crest portions and trough portions extending in parallel to each other in an axial direction of the tube and arranged alternately in a circumferential direction of the tube. The ratio d/P of a depth d of each of the trough portions to a pitch P of the crest portions defined as P=.pi.D/n is set in the range of 0.1 to 0.4; the depth d is set in the range of 1.50 to 2.00 mm; the ratio R.sub.2 /d is set in the range of 2.5 to 6.0; the ratio R.sub.1 /R.sub.2 is set larger than 1, where n represents a positive integer, R.sub.1 represents a radius of curvature of an outer top surface of each crest portion, R.sub.2 represents a radius of curvature of an outer bottom surface of each trough portion, and D represents a diameter of a circumscribed circle of the crest portions.

Abstract: A picture element data density conversion apparatus, enabling arbitrary amounts of data density reduction to be independently selected for the horizontal (i.e. main) and vertical (i.e. secondary) scanning directions of a picture field, executes processing along a continuous path in which horizontally successive input values along each line of the field are first periodically selected and horizontal weighted averaging between specific pairs of these selected values is executed, then periodic selection of successive lines of the horizontal weighted average values thus obtained is executed, and vertical weighting averaging between vertically corresponding pairs of values in the selected line pairs is performed, to obtain density-reduced output data.

Abstract: A first set of different color signals represented in a colorimetric system is converted into a second set of different color signals represented in another colorimetric system. Predetermined main parts of the second set of the color signals are determined in response to predetermined first portions of the first set of the color signals. Calculation coefficients are determined in response to the first portions of the first set of the color signals. Predetermined subordinate parts of the second set of the color signals are calculated from predetermined second portions of the first set of the color signals and the calculation coefficients according to an interpolation. The determined main parts of the second set of the color signals and the calculated subordinate parts of the second set of the color signals are combined into a whole of the second set of the color signals.

Abstract: There is provided an improved image reader. In the image reader, light from an object is converted into an analog signal by a photoelectric converter. The signal is quantized by an A/D converter on the basis of top and bottom reference voltages to produce a digital picture signal. A digital picture signal corresponding to a dark current flowing to the photoelectric converter is stored in a memory as a dark current data. Also a digital picture signal corresponding to the optical strength of predetermined level is stored in another memory as a white level data. Then, the top and bottom reference voltages are produced which correspond to the top and bottom quantization-threshold values on the basis of the dark current and white level data, respectively. The top and bottom reference voltages are then respectively applied to the A/D converter to produce the digital picture signal without signal distortion.

Abstract: An apparatus for scanning an image, comprising a main unit body casing, a first original platen having a transparent surface on which a light-reflective original is placed, a second original platen movable in a horizontal direction inside the main unit body casing upon which platen a light-transmissive original is placed, a light source that irradiates light to the first and second original platens, an image sensor, and an optical apparatus disposed inside the body casing, and which respectively passes reflected light from the original placed on the first original platen and light transmitted through the original placed on the second original platen to the image sensor.

Abstract: A frame of photographic film is optoelectronically scanned after development to produce an electronic image which is analayzed to determine the exposure and development conditions of the film. Tone conversion signals are generated in accordance with the analyzed conditions to convert the tone characteristics of the electronic image to optimal values and thereby compensate for non-standard exposure and development. The electronic image of the entire frame, or alternatively only a part of the electronic image corresponding to an unexposed area of the frame, may be used to determine the development conditions.

Abstract: A color image pickup device comprises an image pickup tube, a color stripe filter comprising a plurality of stripes, a circuit for obtaining a color multiplexed signal by sampling color information from the color stripe filter and multiplexing color components obtained by the sampling in a direction perpendicular to the scanning direction, and a circuit for producing a color demodulated signal by subjecting the color multiplexed signal to a color demodulation. The color stripe filter may be arranged on the image pickup tube so that a longitudinal direction of the stripes is approximately parallel to a scanning direction of the image pickup tube, and the sampling may be performed at sampling points which are deviated in the scanning direction for each scanning line.

Abstract: A color image pickup device comprises an image pickup tube, a color stripe filter comprising a plurality of stripes, a circuit for obtaining a color multiplexed signal by multiplexing color components obtained via the color stripe filter in a direction perpendicular to a scanning direction of the image pickup tube, and a circuit for producing a color demodulated signal by subjecting the color multiplexed signal to a color demodulation. The color stripe filter is arranged on the image pickup tube so that a longitudinal direction of the stripes thereof is substantially parallel to the scanning direction.

Abstract: A color image pickup device comprises an image pickup tube, a color stripe filter comprising a plurality of stripe groups each having a plurality of stripes, and a circuit for obtaining a color multiplexed signal by multiplexing color components obtained via the color stripe filter in a direction perpendicular to the scanning direction for every one stripe group. The color stripe filter is arranged on the image pickup tube so that a longitudinal direction of the stripes of the color stripe filter is substantially parallel to a scanning direction of the image pickup tube. A color demodulated signal and/or a luminance signal are/is produced from the color multiplexed signal.

Abstract: In a color imaging apparatus, an optical image is focused on a photoelectrical conversion target of a color image pickup tube through a color stripe filter and converted to an electrostatic image, the latter being scanned line-by-line in rectangular raster form by an electron beam to generate a color multiplexed video signal. First and second index stripe electrodes are located adjacent to edges of the raster area to be scanned at the beginning of each field and at the beginning of each line. A memory is provided to store field and line index signals generated by the index electrodes as well as a reference video signal generated by the target illuminated with light of a predetermined color.

Abstract: In a color imaging apparatus, an optical image is focused on a photoelectrical conversion target of a color image pickup tube through a color stripe filter having a plurality of successively arranged recurrent groups of different color stripes and converted to an electrostatic image which is scanned in rectangular raster form by an electron beam to generate a luminance signal and a color-multiplexed video signal. The leading and trailing edges of the luminance signal are detected by an edge detector to generate a control signal having first and second polarities in response to the detection of the leading and trailing edges, respectively. The color multiplexed signal is phase-controlled with respect to the leading and trailing edges of the luminance signal in accordance with the control signal by a variable delay line or by a pair of beam deflection plates.

Abstract: In a single-tube color image pickup apparatus, an optical image is passed through a color stripe filter having recurrent groups of different color stripes to a photoelectrical conversion target, which is scanned by an electron beam to generate a video signal comprising a carrier having a frequency inversely proportional to the intervals at which the recurrent groups of filter strips are arranged. The carrier is modulated in phase with the stripes of each group and in amplitude with the intensity of the optical image. Prior to operation, the target is uniformly illuminated with light of a predetermined color to generate the carrier, which is stored into a field memory. During operation the memory is repeatedly addressed to generate a reference signal. The frequency of the reference signal is converted so that the video signal and the frequency-converted reference signal have a frequency ratio of 1:2 and an opposite phase relationship therebetween.

Abstract: A phase-locked loop is supplied with a random two-level code sequence derived from a clock pulse having a frequency f.sub.0 to generate a local clock pulse which is in phase and frequency synchronization with the clock pulse. The local clock pulse is supplied by means of a voltage control oscillator controlled in accordance with a phase difference signal and a phase supplement signal. The phase difference signal is indicative of the difference in phase between an input signal and a discrimination signal. The phase supplement signal is derived by a signal generator responsive to the phase difference signal and the local clock pulses.

Abstract: A luminance signal and a chroma signal of a color video signal are processed respectively such that first and second signals are generated, where the first signal indicates the contour line of images represented by the video signal and the second signal includes noise included in the chroma signal and a signal component having an amplitude substantially equal to the peak to peak value of the noise. These first and second signals are then fed to either a switching circuit or a multiplier so that a resultant output signal having only the noise is obtained. The noise components are then subtracted, by way of a subtractor, from the chroma signal so that a chroma signal having no noise will be obtained.

Abstract: A color video signal processing device for a color image pickup apparatus which allows the saturation of a particular primary color to be enhanced with a good S/N ratio and without affecting the other colors. The image pickup apparatus generates a multiplex color signal which is made up of a low frequency range signal containing all the three primary color signal components and a high frequency range carrier signal modulated with first and second primary color signal components, which are predetermined by the colors of a color stripe filter installed in the image pickup apparatus, and in turn these signals and processed and transformed generally to three primary color video signals and a luminance signal. The low frequency range and high frequency range signals are separated from the color multiplex signal. The separated high frequency range signal contains a fundamental component and a harmonic component. The fundamental component is subjected to envelope detection.

Abstract: In a single-tube color imaging apparatus, the pickup tube includes a photoelectrical conversion target and a filter having recurrent groups of different color stripes through which an optical image is passed to the target. The target is scanned by an electron beam to produce a video signal having a frequency inversely proportional to the intervals at which the recurrent groups are arranged. The video signal varies in phase with the relative values of primary color components contained in the image passing through the stripes of each group and in amplitude with the intensity of the primary color components. Prior to normal operation, the target is uniformly illuminated with light of a predetermined color to generate a reference video signal, which is stored in a field memory. During normal operation, the reference signal is repeatedly read out of the memory and compared by frequency and phase comparators with the video signal from the target.

Abstract: A color TV imaging apparatus has a color TV imaging device which generates a multiplex color TV video signal by means of a photoelectric transducer section equipped with a color separation stripe filter. A first bias light supply device is located in a front portion of the imaging device where the transducer section is formed, in order to apply first bias light which improves color reproducibility in dark scenes. Disposed in a rear portion of the imaging device is a second bias light supply device which applies second bias light to the transducer section which reduces afterimages. The quantity of the second bias light is predetermined to be larger than that of the first bias light.

Abstract: A noise reduction circuit is designed to eliminate noise in a color signal of a color video signal without introducing distortion in the waveform of the color signal. The noise reduction circuit is especially designed to eliminate the noise included in a high-frequency component of the color signal. A first circuit passes as an output thereof a signal obtained from the high-frequency component during a time period which is in accordance with a point in a luminance signal of the color video signal where a change in luminance occurs. A second circuit adds the output of the first circuit with the color signal from which the high-frequency component has been eliminated, so as to produce a color signal from which the noise has been substantially eliminated.