A distributed feedback semiconductor laser which is characterized in that periodic corrugations are performed in the surface of an InGaAsP quaternary layer so that an InP layer is grown thereon so as to overcome difficulties in prior arts.

A distributed feedback semiconductor laser which has, in an active layer or an adjoining layer, first corrugations causing periodic refractive index variations in the travelling direction of light and performs laser oscillation by the injection of a current into said active layer portion. In accordance with the present invention, second corrugations are formed to be aligned obliquely to said first corrugations, thereby causing additional loss to the TM mode to permit oscillation in the TE mode a...

Apparatus for providing the operator of a light projector suitable for performance lighting and capable of beam azimuth and elevation control with data as to the current values of the projector's adjustable parameters. Current azimuth and elevation data is presented both visually, by means of a viewfinder mounted on the projector, and numerically, by means of digital displays. Alternatively, visual feedback may be provided with an imaging device having a field of view substantially the same as t...

Positive feedback of an acoustic signal from a loud speaker to a microphone of a loud speaker system, i.e., howling, is prevented by randomly phase shifting an electric signal containing audio information supplied to the speaker. The random phase shifting is provided by variably delaying the electric signal in a serial analog register having a shift rate determined by an output signal of a pseudo random code generator.

This invention is directed to a digital feedback control system. The control system includes a controlled device which generates an output signal representative of the operation of that device, with that output signal being a relatively high frequency carrier signal having a relatively slowly varying (compared to the carrier signal) envelope. The control system further includes a difference network for generating an error signal representative of the difference between an input command signal an...

The switching power supply has pulse width modulation controller 51 isolated by transformer 35, which is connected by line 33 to the output, VO, across lines 27 and 29. An alternating input is obtained from transistor 19 acting as a switch controlled by alternating signals on line 15 connected to node C. Diode 37 in series with resistor 39 provides damping. Response is very fast and effective, and the input elements, including controller 51, are fully isolated.

An improved bootstrapped shunt feedback amplifier is provided in which a minimum number of transistors are arranged to provide a higher slew rate of output voltage at lower power, while minimizing distortion and thus providing a more precise signal replication. Features include the use of three-terminal composite transistors to increase bandwidth and bootstrapping to improve amplifier response while reducing voltage stress on the active devices.

A tactile feedback switch having a contactor element having a curvilinear portion which temporarily changes from a substantially convex shape to a substantially concave shape upon movement of the contactor element into engagement with an electrical contact. An indentation in the contactor element reduces the force otherwise needed to be applied to the top portion of the contactor element in order to maintain the contactor element in engagement with the electrical contact.

A positive feedback amplifier circuit for possible use with a semiconductor memory device includes first and second MOS transistors whose current paths are connected together between two power source terminals, the gate of the first MOS transistor being connected to a clock. A third MOS transistor has a current path connected between one of the power source terminals and the gate of the second MOS transistor and also has a gate connected to the junction between the first and second MOS transisto...

A method and apparatus by which the output value of a resolver position detection system is compensated for systematic phase shift errors produced by signal conditioning circuitry through which the signal passes.