Abstract: A projection-type display apparatus for projecting an image onto a screen includes a light source, a signal processing unit for processing an input image signal to output a first image signal representing first primary-color information R1, G1, and B1 representing values of red, green, and blue components of an image to be projected, a signal conversion unit for converting the first image signal into a second image signal representing a coefficient M which depends on luminance of the image to be projected defined by the first primary-color information R1, G1, and B1, and into a third image signal representing second primary-color information R2=R1/M, G2=G1/M, and B2=B1/M.

Abstract: The illumination optical system for guiding a light emitted from a light source to an object to be illuminated along an optical path includes a first reflecting mirror reflecting a part of a light which is moving in a forward direction along the optical path to move away from the light source and a second reflecting mirror reflecting a part of a light which is reflected from the first reflecting mirror and moving in a reverse direction along the optical path to approach the light source. The first reflecting mirror has an opening facing a light-entering surface of the object to be illuminated, and the second reflecting mirror has a window that allows the light emitted from the light source to pass therethrough, whereby an optical cavity is constituted by the first and second reflecting mirrors.

Abstract: A projection-type display apparatus that has enhanced the sense of being present by adaptively adjusting, with a simple constitution, projection illumination, depending on an image signal, without causing color changes and by increasing apparent contrast. The projection-type display apparatus includes a light source, a liquid crystal light valve that modulates light emitted from the light source by turning its light polarization plane, and a projection lens that projects the light modulated by the liquid crystal light valve onto a projection surface, wherein a pivotable light polarizer is arranged between the light source and the liquid crystal light valve. The black level of an image is adjusted by adaptively pivoting the light polarizer in response to the image signal.

Abstract: A protection panel is provided that enhances the color quality and/or contrast of a rear projection television set. The protection panel has a spectral transmittance that peaks at dominant wavelengths of red, green, and blue light, and that is reduced at wavelengths between red and green light and between green and blue light. The spectral transmittance at the dominant wavelengths is between sixty and eighty percent. Preferably, the spectral transmittance at the wavelengths between red and green light and between green and blue light are at least five percent less than at the dominant wavelengths. In addition, the spectral transmittance at a dominant wavelength of red light is about five percent less than at a dominant wavelength of blue light to reduce blue color saturation.

Abstract: A projection television has a unit for reflecting OFF light not advancing toward a screen of light emitted by a reflection type light modulating element and a unit for controlling the amount of the reflecting OFF light and returns the OFF light which has not been used in a conventional device to the light source to reuse the OFF light. This configuration increases the utilization efficiency of the light and, as a result, can realize a powerful projection television having a bright projection image.

Abstract: In a color image projection apparatus using a color wheel 51 to illuminate a spatial optical modulator 8 with light in color sequence, light reflected from the color wheel 51 is added to light having passed through the color wheel, and the combined light is spatially modulated by the spatial optical modulator 8 to form an image. If the light reflected at the incident surface 60a of the color wheel 51 is guided to the exit surface 60b of the color wheel 51, and combined with the light having passed through the color wheel, the light utilization efficiently is improved. Any type of images can be projected with improved brightness.

Abstract: Data separating means extracts intra-frame or intra-field encoded blocks from an intra-frame or intra-field encoded, and inter-frame or inter-field encoded digital video signal, and a digital audio signal contained in an input bit stream. Error correction code appending means appends error correction codes to the extracted intra-encoded blocks. Recording means records the data having the error correction code appended, in special replay data recording areas predefined on the magnetic recording tape. During fast replay or slow replay, error correction is achieved even for the replay signal with a low output level and a poor symbol rate.

Abstract: A screen-noise eliminating apparatus including beam-spot-length control means for increasing or decreasing the vertical length of a beam spot on a display screen generated by an electron of a cathode-ray tube for displaying a TV signal; vertical enhancement means for enhancing a given vertical-direction spatial frequency characteristic of said TV signal; and noised elimination control means for controlling said beam-spot-length control means and said vertical enhancement means so as to compensate according to the increase of decrease of said beam spot length.

Abstract: Data separating means extracts intra-frame or intra-field encoded blocks from an intra-frame or intra-field encoded, and inter-frame or inter-field encoded digital video signal, and a digital audio signal contained in an input bit stream. Error correction code appending means appends error correction codes to the extracted intra-encoded blocks. Recording means records the data having the error correction code appended, in special replay data recording areas predefined on the magnetic recording tape. During fast replay or slow replay, error correction is achieved even for the replay signal with a low output level and a poor symbol rate.

Abstract: In a beam current limiting circuit for a video projector, an average current is limited under closed loop control containing an anode current detection circuit 5. On the other hand, a cathode current detection circuit 107 comprises a first resistor and a second resistor in series to a cathode current circuit and detects a cutoff current at the voltage across the first resistor and an average current at the voltage across the second resistor. An offset addition circuit 11 is provided for correcting the detection value of the average current based on the maximum value of detected cathode current, and beam current is limited. Further, means 15 for detecting time change of anode current is provided and if the current value does not change for a long time, the beam current is limited to a smaller value.

Abstract: Data seperating means extracts intra-frame or intra-field encoded blocks from an intra-frame or inter-field encoded digital encoded, and inter-frame or inter-field encoded digital video signal, and a digital audio signal contained in an input bit stream. Error correction code appending means appends error correction codes to the extracted intra-encoded blocks. Recording means records the data having the error correction code appended, in special replay data recording areas predefined on the magnetic recording tape. During fast replay or slow replay, error correction is achieved even for tile replay signal with a low output level and a poor symbol rate.

Abstract: A digital VTR for magnetically recording and replaying a bit stream, includes a detector, an extractor, a mode designator, and an output unit. The detector detects intra-picture data in the bit stream being replayed from tracks in a magnetic medium. The extractor extracts the intra-picture data from the bit stream based on output from the detector. The mode designator designates one of a normal replay and a slow replay as a replay mode. The slow replay is replay performed at a speed slower than normal replay. The output unit stores the extracted intra-picture data, and outputs only the extracted intra-picture data as replay picture data when the slow replay mode is designated.

Abstract: A tracking error signal is detected using an error detector, from cross-talk components at a point in each of the regions of several duplication areas from which reproduction is possible, and tracking control is performed using a servo circuit, based on the average value of the error signals or the average of the maximum and minimum of the peak values of the error signals from the respective areas during one scan. Even when a large amount of fast playback data is recorded, and track non-linearity is present, the fast playback can be reproduced without fail, and signals in fast playback data regions at a plurality of locations can be obtained without fail.

Abstract: The digital VTR includes an extractor, variable-length decoder, quantizer and variable-length encoder. The extractor receives digital data divided into blocks, and which is quantized and variable-length coded on a block-by-block basis. Portions of the digital data are encoded according to a first type of encodation, and other portions of the digital data are encoded according to a second type of encodation. The extractor identifies and extracts the digital data encoded according to the first type of encodation. The variable-length decoder variable-length decodes the extracted portions of the digital data, while the quantizer quantizes the decoded data output by the variable length decoder. The variable length encoder variable-length encodes the quantized decoded data to form special-playback data. Alternatively, a convertor converts the extracted portions of the digital data into variable-length coded data having different quantization steps to form the special-playback data.

Abstract: A data separating device extracts intra-frame or intra-field encoded blocks from an intra-frame or intra-field encoded, and inter-frame or inter-field encoded digital video signal, and a digital audio signal contained in an input bit stream. An error correction code appending device appends error correction codes to the extracted intra-encoded blocks. A recording device records the data having the error correction code appended, in special replay data recording areas predefined on the magnetic recording tape. During fast replay or slow replay, error correction is achieved even for the replay signal with a low output level and a poor symbol rate.

Abstract: A video signal is divided into blocks, and an orthogonal transform is performed on each block to obtain transformed coefficients. Of the transformed coefficients thus obtained, dominant transformed coefficients are selected from a low-frequency area and a high-frequency area, and based on the dominant transformed coefficients, an evaluation value is calculated, using which value a specific pattern in the video signal is detected. Based on the specific pattern thus detected, an optimum quantization step size is decided, and the transformed coefficients are adaptively quantized, thus preventing image quality degradation.

Abstract: Data separating means extracts intra-frame or intra-field encoded blocks from an intra-frame or intra-field encoded, and inter-frame or inter-field encoded digital video signal, and a digital audio signal contained in an input bit stream. Error correction code appending means appends error correction codes to the extracted intra-encoded blocks. Recording means records the data having the error correction code appended, in special replay data recording areas predefined on the magnetic recording tape. During fast replay or slow replay, error correction is achieved even for the replay signal with a low output level and a poor symbol rate.

Abstract: In program retrieval using a magnetic tape in which programs are classified by index signals recorded on the tape, an image at the beginning of each program is displayed in a list on a multi-screen, and a desired program is directly selected using a count value of index signals. In recording, an index signal is recorded at a starting point of recording. When preparing a multi-screen at the time of reproducing, an image reproduced a predetermined time after detection of an index signal is reduced and stored in a memory.

Abstract: Codewords with CDS=0 are mapped in corresponding relationship to datawords, and codewords with CDS>0 and codewords with CDS<0 are paired together and mapped in corresponding relationship to the remaining datawords, and further, codewords with CDS.noteq.0, left unmapped, are mapped in corresponding relationship to the datawords to which the codewords with CDS=0 have been mapped, thus reducing the probability of occurrence of codewords with large DSV in absolute value terms and thereby achieving a further suppression of low-frequency components. Based on the least significant bit of the codeword corresponding to the last dataword and on the current and next datawords, a codeword corresponding to the current dataword is selected, thus realizing high-density recording with good overwrite characteristics.