Abstract: A stereoscopic image display system has a left/right stereoscopic image signal generator for alternately generating left-eye and right-eye image signals at every field, a screen for projecting image light, a liquid crystal shutter. The liquid crystal shutter has a response speed of 1 ms or less, and a contrast between black and white of 100 to 1 or more at a central wavelength of an emission spectrum of a CRT in both parallel and crossing modes of the polarizing plates of the shutter, and a cell gap of 3 .mu.m or less. The screen comprises a Fresnel lens and a lenticular sheet, and the lenticular sheet is disposed in a direction so that a polarizing condition does not generate a phase difference based on the lenticular sheet.

Abstract: An electric motor control system has a motor driver comprising a bridge of switching elements, a pair of failure detectors, and a microcomputer. The motor driver is connected between a battery and an electric motor that is connected between the switching elements. The switching elements are turned on and off according to drive pulse signals supplied from the microcomputer for supplying a pulsed current to the electric motor. The failure detectors monitor the electric energy supplied to the electric motor to detect a period of time in which the supplied electric energy is free of pulses, and supply a signal indicative of the detected period of time to the microcomputer. Based on the signal from the failure detectors, the microcomputer detects a failure when the detected period of time exceeds a predetermined period of time.

Abstract: A four wheel steering system for a motor vehicle with steerable front and rear road wheels, a steering angle sensor for detecting a front wheel steering angle through which the front road wheels are steered, a vehicle speed sensor for detecting a vehicle speed of the motor vehicle, a rear wheel steering mechanism for steering the rear wheels, and a controller for controlling the rear wheel steering mechanism to steer the rear road wheels based on the detected front wheel steering angle and the detected vehicle speed when the front road wheels are steering. The controller controls the rear wheel steering mechanism to steer the rear road wheels in a direction which is opposite to the front road wheels if the detected vehicle speed is relatively low, and also controls the rear wheel steering mechanism to steer the rear road wheels in a direction which is the same as the front road wheels if the detected vehicle speed is relatively high.

Abstract: A liquid crystal display device comprises a converging reflector, a liquid crystal panel, a condenser lens and a projection lens, wherein a correlation between these optical parts and structure of sizes of the optical parts is considered. Accordingly, a convergence efficiency of the device as whole system can be improved. A converging reflector comprises a light source and a reflecting mirror reflecting a light from the light source, wherein a curved plane shape of the mirror is offset radially to the same length as a radius of a light emitting tube of the light source. Accordingly, a convergence efficiency of the converging reflector can be improved.

Abstract: A liquid crystal projector is obliquely disposed in a lower front portion of a cabinet. A first mirror for reflecting light beams of R, G and B coming from the liquid crystal projector is disposed obliquely with respect to the top-bottom, right-left and front-rear directions of the cabinet. A second mirror is disposed so as to be inclined toward a screen. With this configuration, the optical axis of the light beams that extends from the liquid crystal projector to the screen is folded back three-dimensionally. In the liquid crystal projector, the optical axis of a condensing reflector may be slightly inclined from the central axis of a projection lens.

Abstract: A four-wheel steering system on an automobile has front road wheels steerable by a steering wheel and rear road wheels steerable by an electric motor and normally biased to a neutral steering position by a spring. The electric motor is energized by a motor driver to steer the rear road wheels through an angle depending on running conditions of the automobile. The electric motor has a winding and two sets of brushes or connecting terminals connected to opposite terminals of the winding. One of the two sets of connecting terminals is connected to the motor driver. The other of the two sets of connecting terminals is connected to a short-circuiting circuit parallel to the motor driver. In the event of a failure, a controller controls the short-circuiting circuit to short-circuit the winding of the motor through the other set of connecting terminals. The short-circuiting circuit comprises a plurality of relays having respective contacts connected in series between the connecting terminals of the other set.

Abstract: A three color separation/synthesis mirror device for a liquid crystal projector comprises four dichroic mirrors whose joint part has a V-shaped notch in which a higher refractive index is filled thereby to eliminate stray lights. The device may have a prism at the joint part for causing an emitted light to be parallel with an incident light.

Abstract: A front and rear wheel steering system for a motor vehicle with steerable front and rear road wheels includes a front wheel steering mechanism for steering the front road wheels in response to a steering action effected by a steering wheel of the motor vehicle, a neutral positioning mechanism for normally urging the rear road wheels under a resilient force to a steering neutral position, a rear wheel steering mechanism having an electric motor for steering the rear road wheels out of the steering neutral position, and a controller for controlling an electric current supplied to the electric motor depending on the steering action of the steering wheel. The controller reduces the electric current supplied to the electric motor and subsequently holds the reduced electric current while the motor vehicle is at rest and no steering action is effected by the steering wheel.

Abstract: A PWM motor drive control circuit for an electric power steering system, comprising: a bridge circuit having four arms each defined by a transistor; a main control unit for producing a continual direction control signal and a torque control signal of a variable duty ratio to activate the electric motor in a desired direction at a desired torque according to a steering command signal supplied thereto; a sub control unit for producing a second direction control signal according to the steering command signal; and a gate drive control circuit for transmitting the first direction control signal and the torque control signal to the transistors only when the first direction control signal produced by the primary control unit coincides with the second direction control signal produced by the sub control unit.

Abstract: A converging reflector comprises a linear light source having two end points located with a predetermined spacing therebetween, a first reflection surface having a curvature so as to have a focal point at one of the two end points, and a second reflection surface having another curvature so as to have a focal point at the other of the two end points. Accordingly, a light from the linear light source is incident onto the first and second reflection surfaces. Thus, this reflector can project a light as an ideal plane of projection, resulting in improved projection efficiency.

Abstract: A four-wheel steering system for a motor vehicle steers motor vehicle rear wheels based on a steering angle ratio between front and rear wheels based on a vehicle speed, and a front wheel steering angle. The steering angle ratio is of a negative value or a relatively small positive value when the vehicle speed is in a medium speed range or a high speed range and the front wheel steering angle is in a relatively small range. The motor vehicle is controlled to turn well when the front wheel steering angle is in the relative small range while the motor vehicle is running in the medium and high speed ranges.

Abstract: The steering operation of a motor vehicle with steerable front and rear road wheels is controlled by steering the rear road wheels with an actuator such as an electric motor which produces a steering force dependent on a deviation of the actual rear wheel steering angle from a target rear wheel steering angle. The rear road wheels are thus controlled with a characteristic dependent on the coefficient of friction of a road on which the motor vehicle travels and the steering speed at which the motor vehicle is steered.