DISPOSITIF PERMETTANT D'ACTIONNER UNE SIRÈNE POUR PRODUIRE UNE PLURALITÉ DE SONS DIFFÉRENTS, ET PROCÉDÉ D'ACTIONNEMENT D'UNE SIRÈNE POUR PRODUIRE UNE PLURALITÉ DE SONS DIFFÉRENTS

摘要

A vehicle (1) such as a forklift truck, comprises an alarm system (2) for producing an alarm signal in response to reversing of the vehicle (1). The system (2) comprises a device (6) comprising a memory (9) for storing a plurality of selectable discrete digital data signals, each of which when applied to a sounder (3) of the system (2) operates the sounder (3) to produce a sound pattern which is different to the sound patterns produced by the other selectable discrete digital data signals when applied to the sounder (3). A microprocessor (8) controls the operation of the system (2). A pseudo-random number generator (10) generates random numbers so that the discrete digital data signals stored in the memory (9) can be randomly selected each time reverse gear is selected in the vehicle (1). A sensor (11) mounted on the gearbox (4) of the vehicle (1) produces an activation signal on a reverse gear being selected which is read by the microprocessor (8). The microprocessor (8) on detecting an activation signal operates the pseudo-random number generator (10) to generate a random number, and selects the one of the discrete digital data signals corresponding to the generated random number. The microprocessor (8) applies the digital data signal to the sounder (3) through a digital-to-analogue converter (12) and an amplifier (14) for producing an alarm signal to indicate reversing of the vehicle.