Variable speed warning device
AssigneeFederal Signal Corporation
InventorsRichard G. Gibb, Paul D. Graham
Life of this patent
Estimating the term…
Abstract
Method and apparatus for increasing the effectiveness of emergency signalling devices on vehicles. An emergency signalling device such as a flashing light is repeatedly operated at a frequency rate that corresponds to the speed of the vehicle. A minimum repetition rate is employed when the vehicle is slow or stopped so that the signal is not similarly halted, and a maximum rate is employed above a certain speed so that the repetition rate is not at too high of a frequency to be perceived.
Claims22
An emergency lighting device for a motor vehicle, the device comprising, a flashing light, a light transmissive housing for and protecting the flashing light, a detector for detecting the speed of the vehicle, and circuitry responsive to the detector for controlling a flash rate of the flashing light so that the rate varies with both an increase and decrease in the speed of the vehicle in accordance with a predetermined relationship between minimum and maximum visibly discernable flash rates.
A method of operating emergency signalling devices secured to a motor vehicle, the method comprising the steps of, generating an emergency signal that is sensed by an observer as having a cyclical characteristic, maintaining a repetition rate of the cyclical characteristic of the emergency signal at a minimum value for speeds of the motor vehicle below a predetermined lower limit, maintaining the repetition rate of the cyclical characteristic of the emergency signal at a maximum value for speeds of the motor vehicle above a predetermined upper limit, where the cyclical characteristic is discernable to the observer at the maximum value, and adjusting the repetition rate of the emergency signal between the lower and upper limits in response to both increases and decreases in speed.
An emergency signalling device for a vehicle, comprising, a signalling device on the vehicle for broadcasting emergency signals, a detector for converting the speed of the vehicle to a DC voltage having an amplitude that varies with the speed of the vehicle, circuitry for converting the DC voltage to a second electrical signal having a repetition rate corresponding to the speed of the vehicle, circuitry for maintaining the repetition rate between maximum and minimum rates, and means connecting the second electrical signal to the signalling device for broadcasting emergency signals having a repetition rate that varies with both increases and decreases in the speed of the vehicle between maximum and minimum repetition rates.
Dependencies are inferred from the claim text.