Protection device for hammer driving circuits

Claim 1

A device for protecting current pulse circuits coupled to a voltage source by a controllable switching means, comprising: circuit means for checking a voltage level of said switching means, an alarm and cut off means for producing an alarm signal and cutting off said voltage source, whenever said voltage level of said switching means is not between an upper and a lower threshold value during predetermined time intervals.

Claim 2

A device for protecting current pulse circuits coupled to a voltage source by a controllable switching means, comprising: circuit means for checking a voltage level of said switching means, an alarm and cut off means for producing an alarm signal and cutting off said voltage source, whenever said voltage level of said switching means is not between an upper and a lower threshold value during predetermined time intervals.

Claim 5

A device for protecting a plurality of firing circuits of a high speed printer, each firing circuit comprising a storage capacitor, a print electromagnet and an electronic switch connected in series with said print electromagnet, said storage capacitor being charged at recurrent time intervals by a cyclic charging circuit unit, the protecting device com-prising a supervisor circuit having an input terminal and an output terminal, the input terminal being connected to the anodes of an associated plurality of diodes, the cathode of each one of said diodes being connected to the connection between said print electromagnet and said electronic switch of an associated print circuit, said supervisor circuit delivering at its output terminal in succession a first and a second binary level, said first binary level being delivered when the voltage of at least one of said leads connected to said cathodes of said diodes is not between predetermined threshold values.

Claim 6

A device for protecting a plurality of firing circuits of a high speed printer, each firing circuit comprising a storage capacitor, a print electromagnet and an electronic switch connected in series with said print electromagnet, said storage capacitor being charged at recurrent time intervals by a cyclic charging circuit unit, the protecting device com-prising a supervisor circuit having an input terminal and an output terminal, the input terminal being connected to the anodes of an associated plurality of diodes, the cathode of each one of said diodes being connected to the connection between said print electromagnet and said electronic switch of an associated print circuit, said supervisor circuit delivering at its output terminal in succession a first and a second binary level, said first binary level being delivered when the voltage of at least one of said leads connected to said cathodes of said diodes is not between predetermined threshold values.

Claim 7

A device for protecting current pulse circuits, comprising circuit means for checking the voltage of suitable points of said circuits, and alarm and cut-off means for producing an alarm signal and cutting off said circuits, whenever the voltage of any one of said points is not between an upper and a lower threshold value during predetermined time intervals, whereby said alarm signal is given out and said circuits are cut-off whenever the voltage of any one said points remains lower than a predetermined value for a time interval longer than a predetermined value, and whereby a cyclic charging unit delivers a Test Charge signal after the end of the charging of storage capacitors, comprising a bistable, binary switching means having at least a first and a second input lead, and at least an output lead, for delivering on said output lead an alarm and cut-off signal in response to the coincident application of the Test Charge signal to said first input lead of a first binary level signal to said second input lead.

Claim 8

A device for protecting current pulse circuits, comprising circuit means for checking the voltage of suitable points of said circuits, and alarm and cut-off means for producing an alarm signal and cutting off said circuits, whenever the voltage of any one of said points is not between an upper and a lower threshold value during predetermined time intervals, whereby said alarm signal is given out and said circuits are cut-off whenever the voltage of any one said points remains lower than a predetermined value for a time interval longer than a predetermined value, and whereby a cyclic charging unit delivers a Test Charge signal after the end of the charging of storage capacitors, comprising a bistable, binary switching means having at least a first and a second input lead, and at least an output lead, for delivering on said output lead an alarm and cut-off signal in response to the coincident application of the Test Charge signal to said first input lead of a first binary level signal to said second input lead.

Claim 9

A device for protecting current pulse circuits, comprising circuit means for checking the voltage of suitable points of said circuits, and alarm and cut-off means for producing an alarm signal and cutting off said circuits, whenever the voltage of any one of said points is not between an upper and a lower threshold value during predetermined time intervals, whereby said current pulse circuits are charged at recurrent intervals of a temporal cycle by a cyclic device, said alarm signals being gIven out and said circuits being cut-off whenever the voltage of any one of said points is not between said threshold values during predetermined recurrent time intervals of said cycle, and whereby a validation signal is deivered at a short predetermined time after activating said cyclic charger, comprising a bistable switching means, having at least a first and a second input lead, and at least an output lead, for delivering on said output lead an alarm and cut-off signal in response to the coincident application of said validation signal to said second input lead and of said first binary level signal to said second input lead.

Claim 10

A device for protecting current pulse circuits, comprising circuit means for checking the voltage of suitable points of said circuits, and alarm and cut-off means for producing an alarm signal and cutting off said circuits, whenever the voltage of any one of said points is not between an upper and a lower threshold value during predetermined time intervals, whereby said current pulse circuits are charged at recurrent intervals of a temporal cycle by a cyclic device, said alarm signals being gIven out and said circuits being cut-off whenever the voltage of any one of said points is not between said threshold values during predetermined recurrent time intervals of said cycle, and whereby a validation signal is deivered at a short predetermined time after activating said cyclic charger, comprising a bistable switching means, having at least a first and a second input lead, and at least an output lead, for delivering on said output lead an alarm and cut-off signal in response to the coincident application of said validation signal to said second input lead and of said first binary level signal to said second input lead.

Claim 11

A device for protecting a plurality of printing firing circuits of a high speed printer, each firing circuit comprising a storage capacitor, a print electromagnet, and an electronic switch connected in series with said print electromagnet, said storage capacitors being steadily maintained at a predetermined voltage by a stabilized direct-current power supply, the device comprising a supervisor circuit having an input terminal and an output terminal, the input terminal being connected to the anodes of an associated plurality of diodes, the cathode of each said diode being connected to the output lead of an integrating circuit comprising a resistor and a capacitor series connected, the input lead of each integrated circuit being connected to the connection lead between said print electromagnet and said electronic switch of an associated print circuit said supervisor circuit delivering at its output terminal an alarm and cut-off signal whenever the voltage of the output lead of at least one of said integrating circuit decreases under a predetermined value.

Claim 12

A device for protecting a plurality of printing firing circuits of a high speed printer, each firing circuit comprising a storage capacitor, a print electromagnet, and an electronic switch connected in series with said print electromagnet, said storage capacitors being steadily maintained at a predetermined voltage by a stabilized direct-current power supply, the device comprising a supervisor circuit having an input terminal and an output terminal, the input terminal being connected to the anodes of an associated plurality of diodes, the cathode of each said diode being connected to the output lead of an integrating circuit comprising a resistor and a capacitor series connected, the input lead of each integrated circuit being connected to the connection lead between said print electromagnet and said electronic switch of an associated print circuit said supervisor circuit delivering at its output terminal an alarm and cut-off signal whenever the voltage of the output lead of at least one of said integrating circuit decreases under a predetermined value.