Oki Electric Industry Co., Ltd.

Fuji Photo Optical Co., Ltd.

Nippon Hoso' Kyokai

Victor Company

Oki Electric

Hirohisa Shishikura

Iwao Sagara

Osamu Yamada

Saburo Numata

Ichiro Sase

Akio Yanagimachi

Ikuo Anada

Shigeharu Ueguri

In a combination of a printed wiring board and a memory device selecting circuit provided on the printed wiring board, the printed wiring board is provided with a predetermined number of device mount areas and a conductor pattern for connection with memory devices in the device mount areas. The number of the memory devices actually mounted in the mount areas is set in a device-number setting device, and in accordance with a predetermined bits of address code and on the basis of the number set, device select signals are produced, and are distributed over the conductor pattern. Identical printed wiring boards and memory device selecting circuits can be used, without alteration or re-designing, for forming electronic devices having different memory capacities or different number of memory devices.

Combination of a printed wiring board and a memory device selecting

An error correction system for a difference set cyclic (272,190) code with 190 data bits and 82 test bits in a coded transmission teletext system which transmits character information on the vertical blanking interval of a television signal has been improved in peripheral circuits for operating an error correction circuit. A first improvement is to correct only designated packets which are in frame synchronization condition and/or designated by an index register. A second improvement is to handle shortened (L,k) code where L is less than 272, using common hardware. A third improvement is selection of three operational modes of data to be corrected. In the first mode, uncorrected data is supplied by an external circuit, and said uncorrected data is stored temporarily in a buffer memory, and corrected data is stored in said buffer memory again to supply external circuit corrected data. Transfer of data between the buffer memory and the error correction circuit is handled by wired logic hardware apparatus. In a second mode, uncorrected data and corrected data are provided in a buffer memory but no external circuit is concerned in operation of the present system. In a third mode, no buffer memory is used, and an external circuit supplies uncorrected data to an error correction circuit directly and receives corrected data directly from the error correction circuit.

Error correction system for difference set cyclic code in a teletext

An error correction system for a difference set cyclic (272, 190) code with 190 data bits and 82 test bits in a packet which is transmitted on a vertical blanking interval of a television signal has been improved. The present system comprises a buffer memory for storing an original data which is subject to correction and corrected data, and an error correction circuit having at least a syndrome register, a majority circuit and a data register. The data transfer between the buffer memory and the error correction circuit is effected by wired logic hardware means without using software operation time of a programmed computer so that computer operation time is not wasted merely for error correction. A correction number counter is provided for counting the number of corrected bits for adjusting the threshold level for determining 1 or 0 of a reception signal, adjusting criterion of operation of the majority circuit in the error correction circuit, and the stopping of error correction operation in case of too many errors.

Error correction system in a teletext system

Light emitting elements such as light emitting diodes provided in the viewfinder of a camera are connected with a light measuring circuit including a photodetector through an A-D converter, a decoder and a gate circuit so that the light emitting elements may indicate exposure information in a digital form in accordance with the output of the light measuring circuit. An oscillator is connected with the A-D converter and the gate circuit for giving sampling pulses to the A-D converter and clock pulses to the gate circuit. Between the oscillator and the gate circuit is provided a duty modulator to change the duty cycle of the square wave transmitted from the oscillator to the gate circuit. The duty modulator is connected with the light measuring circuit or the A-D converter so as to control the duty cycle of the square wave in accordance with the output from the light measuring circuit. the brightness of the light emitting elements in the viewfinder is controlled so as to be proportional to the brightness of the image viewed through the viewfinder.

Device for indicating exposure information in the viewfinder of a camera

An exposure indicating means comprising a plurality of light emitting elements which are selectively energized to indicate exposure information in a digital form is connected with an exposure measuring circuit. The light emitting elements are connected with a warning circuit. The warning circuit comprises a warning signal generator which generates a warning signal when a warning is required, a square wave generator which constantly generates a square wave and an AND circuit which transmits the square wave to the light emitting elements when the warning signal is transmitted thereto. The light emitting elements are intermittently turned off by the square wave coming from the AND circuit. The frequency of the square wave is selected so that the intermittent turning off of the light emitting elements is sensed by the photographer viewing through the viewfinder of the camera.

Warning device for photographic cameras

An accurate, simple and compact analog-to-digital converter has been found. The converter comprises

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Tokyo, Japan

Hirohisa Shishikura