Hitachi, Ltd.

Ikegami Tsushinki Co., Ltd.

Hitaci, Ltd.

Sumio Nakagawa

Toshio Tanaka

Kenzi Toudo

Motoshi Miyanaka

Kenji Todo

Seiichi Tachi

Masaya Oka

Motosi Miyanaka

Yoshinori Kudo

A circuit for measuring a carrier-to-noise ratio or a bit error rate of demodulated I and Q digital signals obtained by demodulating an input carrier wave which is modulated and transmitted under a carrier modulation transmission system including a discriminating circuit for producing a discrimination signal each time the demodulated digital signal comes within predetermined windows set on a signal space of the I and Q signals, a counter for counting the discrimination signals during a predetermined time interval, and a calculating circuit for calculating a carrier-to-noise ratio or bit error rate in accordance with a count value with reference to a previously stored relationship between count values and carrier-to-noise ratios or bit error rates.

Circuit for measuring transmission quality of demodulated digital signal

A three-dimensional image display system comprising a video information memory, storing video information in the form of a perspective view, a reading circuit for reading out the video information stored in the video information memory while scrolling the stored video information in an oblique direction with respect to the perspective view, and a display for displaying in perspective the read out video information in such a way that the displayed picture is obliquely scrolled as time elapses.

Three-dimensional image display system

Combustion control circuit

A combustion control apparatus in which a predetermined number of pre-purge and igniting cycles are repeated until ignition takes place successfully. A pre-purge time interval of the second and subsequent igniting cycles is selected shorter than that of the first igniting cycle. When an existing combustion control element which is capable of performing the igniting cycle only once is employed, the intended combustion control is performed by appropriately controlling a reset terminal of the existing combustion control element of signals representative of expirations of the pre-purge time interval and the ignition time interval. The number of the igniting cycles is counted by a counter for stopping operation of the combustion apparatus when a predetermined count value is attained. A novel circuit for the combustion control element is also disclosed.

Combustion control apparatus

A check circuit for checking operation of timers of a digital type combustion process control apparatus comprises flip-flops each having a preset terminal. The preset state of the flip-flops is inverted by an operation starting signal. The inversion is detected by a detector circuit the output signal of which is utilized for driving the control circuits for a combustion apparatus. The detector circuit is composed of a flip-flop circuit having input terminals applied with the operation initiating signal and the inverted output signal from the timer circuit.

Check circuit for combustion process control timer

Disclosed is a combustion control apparatus of digital type, in which a fault is warned of unless ignition resumes in a predetermined time after the start of igniting operation in the reignition when fuel flaming is extinguished during combustion. The predetermined time is called safety time and the combustion control apparatus can exactly obtain such a required time or period as the safety time. With such a digital type combustion control apparatus, the safety timer for establishing the safety time comprises flip-flops adapted to count reference clock pulses. In this apparatus, the circuit for generating the reference clock pulses is set and reset by the flame extinction signal to synchronize the clock pulses and the flame extinction signal so that the safety time may be free from error. This concept can be applied to determine the prepurge time.

A combustion control system applicable universally to various types of combustion apparatus operating with different control timing and different fuel is disclosed. The combustion control system includes a data selector circuit, a control circuit, and a control timer circuit using a counter as timing means. The data selector circuit includes a circuit section for providing pre-purge timing and another circuit section for providing ignition timing as required. The control circuit includes an R-S flip-flop controlled by the pre-purge timing produced by the data selector circuit section.

Growing community of inventors

Tokyo, Japan

Sumio Nakagawa