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;
a positive voltage generator generating a positive voltage signal; and
a negative voltage generator generating a negative voltage signal, the voltage of at least one of the positive voltage signal and the negative voltage signal having an absolute value higher than an absolute value of the voltage of the battery power supply, the positive voltage signal and the negative voltage signal cooperating to form a high voltage pulse in the dark state drive signal.
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 leading edges of the positive and negative voltage signals are synchronized.
5. The auto darkening eye protection device of claim 1 , 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.
6. The auto darkening eye protection device of claim 5 , wherein the directional control circuit includes at least two diodes.
7. The auto darkening eye protection device of claim 1 , 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.
8. The auto darkening eye protection device of claim 7 , wherein the directional control circuit includes at least two diodes.