Eye-protection device having dual high voltage switching
View Patent ↗An auto darkening eye protection device comprising a shutter assembly and a control circuit. The shutter assembly is adjustable between a clear state and a dark state. The control circuit comprises a sensing circuit, a weld detect circuit, and a delivery circuit. The sensing circuit senses incident light and provides an output indicative of the incident light. The weld detect circuit receives the output of the sensing circuit, and enables a dark state drive signal to be delivered to the shutter assembly. The delivery circuit outputs the dark state drive signal to the shutter assembly to switch the shutter assembly from the clear state to the dark state upon enablement by the weld detect circuit. The dark state drive signal includes a high voltage pulse followed by a stable AC waveform. The high voltage pulse is formed by a positive voltage signal and a negative voltage signal.
1. An auto darkening eye protection device comprising:
a shutter assembly adjustable between a clear state and a dark state; and
a control circuit comprising:
a battery power supply having a voltage;
a sensing circuit sensing an occurrence of a welding arc and providing an output indicative of the occurrence of the welding arc;
a weld detect circuit receiving the output of the sensing circuit, the weld detect circuit enabling a dark state drive signal to be delivered to the shutter assembly; and
a delivery circuit receiving power from the battery power supply and outputting the dark state drive signal to the shutter assembly to switch the shutter assembly from the clear state to the dark state upon enablement by the weld detect circuit, the dark state drive signal including a high voltage pulse followed by a stable AC waveform, the high voltage pulse being formed by a positive voltage signal and a negative voltage signal, the positive voltage signal having a magnitude greater than the voltage of the battery power supply.
2. The auto darkening eye protection device of claim 1 wherein the positive voltage signal and the negative voltage signal are each referenced to ground.
3. The auto darkening eye protection device of claim 1 wherein the high voltage pulse has a voltage in a range from about 15 V to about 120 V, and a time period from about 10 microseconds to about 100 milliseconds.
4. The auto darkening eye protection device of claim 1 , wherein the positive and negative voltage signals having leading edges, and wherein the leading edges of the positive and negative voltage signals are synchronized.
5. The auto darkening eye protection device of claim 1 , further comprising:
a positive voltage generator generating the positive voltage signal; and
a negative voltage generator generating the negative voltage signal, the positive voltage signal and the negative voltage signal being provided to the delivery circuit to form the high voltage pulse.
6. The auto darkening eye protection device of claim 5 , wherein the positive voltage generator includes:
a switching circuit having a charging state and a discharging state;
at least two capacitors, each of the capacitors connected to the switching circuit and a reference voltage to establish charging of the capacitors in the charging state of the switching circuit, and a positive lead of one capacitor electrically connected to a negative lead of another one of the capacitors in the discharging state of the switching circuit;
a directional control circuit connected to the capacitors to permit the flow of current between the positive leads of the capacitors and the reference voltage in the charging state of the switching circuit, and to prevent the flow of current between the positive leads of the capacitors and the reference voltage in the discharging state of the switching circuit.
7. The auto darkening eye protection device of claim 6 , wherein the directional control circuit includes at least two diodes.
8. The auto darkening eye protection device of claim 5 , wherein the negative voltage generator includes:
a switching circuit having a charging state and a discharging state;
at least two capacitors, the capacitors connected to the switching circuit and a reference voltage to establish charging of the capacitors in the charging state of the switching circuit, and a positive lead of one capacitor electrically connected to a negative lead of another one of the capacitors in the discharging state of the switching circuit;
a directional control circuit connected to the capacitors to permit the flow of current between the negative leads of the capacitors and the reference voltage in the charging state of the switching circuit, and to prevent the flow of current between the negative leads of the capacitors and the reference voltage in the discharging state of the switching circuit.
9. The auto darkening eye protection device of claim 6 , wherein the directional control circuit includes at least two diodes.
10. An auto darkening eye protection device comprising:
a shutter assembly adjustable between a clear state and a dark state; and
a control circuit comprising:
a sensing circuit sensing an occurrence of a welding arc and providing an output indicative of the occurrence of the welding arc, the sensor circuit comprising;
a light sensor having a light sensor output;
an amplifier having an input coupled to the light sensor for amplifying the light sensor output to form the output of the sensing circuit, the output of the sensing circuit sufficient to trigger the weld detect circuit to enable the dark state drive signal when the light sensor receives a light input having an intensity indicative of a welding arc being present;
a high-pass filter circuit positioned between the light sensor and the amplifier for blocking DC voltage and passing high frequency signals; and
a non-reactive element positioned in parallel with the high-pass filter circuit for providing a DC bias to the input of the amplifier representative of the light sensor output;
a weld detect circuit receiving the output of the sensing circuit, the weld detect circuit enabling a dark state drive signal to be delivered to the shutter assembly; and
a delivery circuit outputting the dark state drive signal to the shutter assembly to switch the shutter assembly from the clear state to the dark state upon enablement by the weld detect circuit.
11. The auto darkening eye protection device of claim 10 wherein the amplifier comprises a closed loop non-inverting amplifier.
12. The auto darkening eye protection device of claim 10 wherein the high-pass filter circuit includes a capacitor in circuit between the light sensor and the amplifier.
13. The auto darkening eye protection device of claim 10 wherein the non-reactive element is a resistor.
14. An auto darkening eye protection device comprising:
a shutter assembly adjustable between a clear state and a dark state; and
a control circuit comprising:
a sensing circuit sensing an occurrence of a welding arc and providing an output indicative of the occurrence of the welding arc;
a weld detect circuit receiving the output of the sensing circuit, the weld detect circuit enabling a dark state drive signal to be delivered to the shutter assembly; and
a delivery circuit outputting the dark state drive signal to the shutter assembly to switch the shutter assembly from the clear state to the dark state upon enablement by the weld detect circuit, the dark state drive signal including a high voltage pulse followed by a stable AC waveform, the high voltage pulse being formed by a positive voltage signal and a negative voltage signal, the positive voltage signal being generated for a predetermined period of time.
15. The auto darkening eye protection device of claim 14 , wherein the positive voltage signal and the negative voltage signal are each referenced to ground.
16. The auto darkening eye protection device 14 wherein the high voltage pulse has a voltage in a range from about 15 V to about 120 V, and a time period from about 10 microseconds to about 100 milliseconds.
17. The auto darkening eye protection device of claim 14 wherein the positive and negative voltage signals having leading edges, and wherein the leading edges of the positive and negative voltage signals are synchronized.
18. The auto darkening eye protection device of claim 14 further comprising:
a positive voltage generator generating the positive voltage signal; and
a negative voltage generator generating the negative voltage signal, the positive voltage signal and the negative voltage signal being provided to the delivery circuit to form the high voltage pulse.
19. The auto darkening eye protection device of claim 18 , wherein the positive voltage generator includes:
a switching circuit having a charging state and a discharging state;
at least two capacitors, each of the capacitors connected to the switching circuit and a reference voltage to establish charging of the capacitors in the charging state of the switching circuit, and a positive lead of one capacitor electrically connected to a negative lead of another one of the capacitors in the discharging state of the switching circuit;
a directional control circuit connected to the capacitors to permit the flow of current between the positive leads of the capacitors and the reference voltage in the charging state of the switching circuit, and to prevent the flow of current between the positive leads of the capacitors and the reference voltage in the discharging state of the switching circuit.
20. The auto darkening eye protection device of claim 19 wherein the directional control circuit includes at least two diodes.
21. The auto darkening eye protection device of claim 18 , wherein the negative voltage generator includes:
a switching circuit having a charging state and a discharging-state;
at least two capacitors, the capacitors connected to the switching circuit and a reference voltage to establish charging of the capacitors in the charging state of the switching circuit, and a positive lead of one capacitor electrically connected to a negative lead of another one of the capacitors in the discharging state of the switching circuit;
a directional control circuit connected to the capacitors to permit the flow of current between the negative leads of the capacitors and the reference voltage in the charging state of the switching circuit, and to prevent the flow of current between the negative leads of the capacitors and the reference voltage in the discharging state of the switching circuit.
22. The auto darkening eye protection device of claim 19 , wherein the directional control circuit includes at least two diodes.