Optical barrier for detecting moving objects

Claim 2

A barrier as claimed in Claim 1, characterized by the fact that said processing unit (14) comprises: first means for each said photoreceiver (7) for enabling reception of a number of analog signals at least equal in number to said diodes (5); second means (18) for converting said analog signals into digital signals on the basis of a second reference value (Vref) selected from a number of predetermined second values (Vref) stored in a memory block of said processing unit (14); third means (71) for computing, for each said photoreceiver (7), a third value (Sm) defined by the mean of all said signals supplied and converted into digital signals; for computing a fourth value (Stm) defined by the mean of all said third values (Sm); and for computing, by means of said fourth value (Stm), the maximum and minimum values of a range of fifth values; fourth means (72) for determining whether said third values (Sm) are within said range processed by said third means (72); fifth means (73) for computing said first value (Vf) for each said photoreceiver (7), said first value (Vf) being defined by a percentage value of the corresponding third value (Sm); and sixth means (74, 75, 76) for selecting a new second value (Vref) in the event at least one of said third values (Sm) is outside said range of fifth values; for converting said analog signals into digital signals, on the basis of said new second value (Vref); for computing, for each said photoreceiver (7), a new third value (Sm) defined by the mean of all said signals supplied and converted into digital signals; for computing a new fourth value (Stm) defined by the mean of all said new third values (Sm); and for computing, by means of said new fourth value (Stm), a new maximum and minimum value of said range of fifth values.

Claim 3

A barrier as claimed in Claim 2, characterized by the fact that said processing unit (14) comprises seventh means (54) which, in the case of a first operating cycle, provides for automatically determining said first reference value (Vf) of each said photoreceiver (7).

Claim 4

A barrier as claimed in Claim 2 and/or 3, characterized by the fact that said equipment (8) comprises manually operated eighth means (25) for controlling said processing unit (14) and automatically determining said first reference value (Vf) of each said photoreceiver (7).

Claim 5

A barrier as claimed in at least one of the foregoing Claims, characterized by the fact that said processing unit (14) comprises ninth means (52) for computing how many of said photoreceivers (7) are operative; tenth means (61) for determining whether any one of said photoreceivers (7) is faulty, by virtue of generating, in excess of a predetermined time period, a signal whose value is constantly below a predetermined value; and eleventh means (62) for excluding said faulty photoreceiver (7) from the computation performed by said ninth means (52), so that said equipment (8) may function even in the event of impaired operation of said receiving unit (6), in the sense that the number of operative photoreceivers (7) is less than the number of photoreceivers (7) actually installed in said receiving unit (6).

Claim 6

A barrier as claimed in Claim 5, characterized by the fact that said equipment (8) comprises: a first electric block (16) having a number of first indicator lights, one for each said photoreceiver (7); a second indicator light for indicating the barrier is engaged, i.e. for indicating the presence of an object along said path; and a third indicator light for indicating impaired operation of said receiving unit (6); and twelfth means (64) for providing a number of indications, such as constant electrical supply of said first indicator lights corresponding to said photoreceivers (7) dimmed for less than said predetermined time and so indicating the presence of an object along said path; and electrical supply of said second indicator light; said third indicator light being activated by said eleventh means (62).

Claim 7

A barrier as claimed in Claim 6, characterized by the fact that said twelfth means provide for flashing said first indicator lights relative to said faulty photoreceivers (7) excluded from the count performed by said ninth means (52).

Claim 8

A barrier as claimed in Claim 7, characterized by the fact that it comprises a second electric block (22) connected to said equipment (8) and preferably remote from the same for enabling viewing by an operator; said second block (22) presenting a first element (28), activated by said twelfth means (64), for indicating the barrier is engaged, and a second element (29), activated by said eleventh means (62), for indicating impaired operation of said receiving unit (6).

Claim 9

A barrier as claimed in Claim 8, characterized by the fact that said equipment (8) comprises a sound alarm (21) activated by said ninth means (52) upon said ninth means (52) determining that only one of said photoreceivers (7) is operative.

Claim 10

A barrier as claimed in at least one of the foregoing Claims, characterized by the fact that said equipment (8) comprises thirteenth means (26, 27) for evaluating impaired operation of said transmitting unit (4) as a function of the signals generated by said receiving unit (6); a third element (30), activated by said evaluating means (26, 27), for indicating impaired operation of said transmitting unit (4); and a block, activated by said evaluating means (26, 27), for indicating impaired operation of said barrier.

Claim 11

A barrier as claimed in Claim 10, characterized by the fact that said evaluating means comprise: an adding block (26) for adding the signals generated by said photoreceivers (7) in the course of a complete scan of said diodes (5); a comparing block (27), which, depending on the total of the signals generated by said photoreceivers (7), provides for comparing the value of the output signal from said adding block (26) with a predetermined electric reference signal; a block (36) for checking whether all of said photoreceivers (7) are dimmed; a wait block (35) for activating said check block (36) after a predetermined wait time; and a block (37) for indicating impaired operation of said transmitting unit (4) and said barrier, in the event said check block (36) determines said photoreceivers (7) are all dimmed for less than said predetermined wait time.