| 摘要 |
A visual warning system for a railway vehicle, particularly a locomotive, to illuminate the tracks or the right of way (sometimes called a ditch). The system has a first lamp and a second lamp. The first lamp is driven by a first lamp driver responsive to a first pulse width modulated signal, and the second lamp driver is driven by a second lamp driver responsive to a second pulse width modulated signal. A controller produces the first and second pulse width modulated signals in which the duty cycle of the first and second pulse width modulated signals is varied between high and low levels to alternatively turn the first and second lamps approximately fully on and approximately fully off. To turn each lamp approximately fully on, the controller increases, step-wise, the duty cycle of the lamp's respective pulse width modulated signal from the low level to the high level. The system may further include a switch for operating a horn on the vehicle. When this switch is not depressed, the controller maintains both the first and second pulse width modulated signals at either the low or high duty cycle level. When the horn switch is depressed, the controller varies the first and second pulse width modulated signals between the low and high duty cycle levels to alternatively turn the first and second lamps approximately fully on and off, and then after the horn switch is released, continues alternating the first and second lamps approximately fully on and off for a predefined period.
|
