Thermal imager
A thermal imager includes a detector, a lens, a shutter disposed between the detector and the lens, and a motor operably connected to the shutter for moving the shutter between a first and a second position. There is a source of electrical energy operably connected to one or more of the detector, lens and motor by an electrical circuit. The electrical circuit includes one or more of a capacitor, a diode, and a resistor.
1. A thermal imager comprising:
a detector,
a lens,
a shutter disposed between the detector and the lens,
a motor operably connected to the shutter for moving the shutter between a first and a second position, the motor being a two-phase stepper motor, and
a source of electrical energy operably connected to one or more of the detector, lens and motor by an electrical circuit,
wherein the electrical circuit comprises one or more of a capacitor, a diode, and a resistor and the one or more of the capacitor, diode, and resistor reduce one or more of a capacitance, voltage, and inductance of the electrical energy in the electrical circuit to below a nonincendiary level required for intrinsic safety, and
wherein the two-phase stepper motor comprises at least two coils, each coil having a first and a second end and wherein the electrical circuit comprises four resistors, one resistor in electrical communication with each of the first and second ends of each of the at least two coils.
2. A thermal imager according to claim 1 , wherein the voltage is reduced from above or equal to 5 volts to below 5 volts, and thereby the reduced voltage is nonincendiary.
3. A thermal imager according to claim 1 , wherein the detector is a micro bolometer.
4. A thermal imager according to claim 3 , wherein the microbolometer is an infrared Focal Plane Array (FPA) detector comprising a plurality of light sensing pixels.
5. A thermal imager according to claim 4 , wherein the Focal Plane Array (FPA) detector comprises 320×240 pixels.
6. A thermal imager according to claim 1 , wherein the two-phase stepper motor is a 3.3 volt Direct Current (DC) two-phase stepper motor.
7. A thermal imager according to claim 1 , wherein each of the at least two coils has an inductance of from 2.4 to 3.6 mH.
8. A thermal imager according to claim 1 , wherein each of the at least two coils has a resistance of from 12 to 18 ohms.
9. A thermal imager according to claim 1 , wherein each of the at least two coils is a single coil inductor.
10. A thermal imager according to claim 1 , wherein each of the four resistors has a resistance of less than or equal to 12.7 ohms.
11. A thermal imager according to claim 1 , wherein each of the four resistors has a power rating of less than or equal to 0.75 W.
12. A thermal imager according to claim 1 , wherein each of the four resistors has a size of 2010.
13. A thermal imager according to claim 1 , wherein the voltage is reduced from 5 volts to below 5 volts, and thereby the reduced voltage is nonincendiary.
14. A method of obtaining a thermal image using a thermal imager in a hazardous environment, the method including the steps of:
providing a motor for operating a shutter in a thermal imager and a source of electrical energy for powering the motor, the motor being a two-phase stepper motor, wherein the two-phase stepper motor comprises at least two coils, each coil having a first and a second end and wherein the electrical circuit comprises four resistors, one resistor in electrical communication with each of the first and second ends of each of the at least two coils,
providing an electrical connection between the motor and the source of electrical energy,
providing one or more of a capacitor, a diode, and a resistor in the electrical connection, and
passing the electrical energy through one or more of a capacitor, a diode, and a resistor in the electrical connection between the motor and the source of electrical energy to reduce one or more of a capacitance, voltage, and inductance of the electrical energy in the electrical connection to below a nonincendiary level required for intrinsic safety.
15. A method of obtaining a thermal image according to claim 14 , wherein the method further includes using the diode to limit the resistance of the electrical energy to less than or equal to 12.7 ohms.
16. A method of obtaining a thermal image according to claim 14 , wherein the thermal imager includes a detector and a lens, the method including the step of moving the shutter between a first and a second position, wherein in the first position the shutter is between the detector and the lens, thereby inhibiting the transfer of infrared radiation between the lens and the detector.
17. A method of obtaining a thermal image according to claim 16 , wherein the method includes the step of using the detector to collect infrared data from infrared radiation passing through the lens when the shutter is in the second position.
18. A method of obtaining a thermal image according to claim 16 , wherein the method includes the step of using the detector to collect infrared data from infrared radiation emitted from a surface of the shutter when the shutter is in the first position.
19. A thermal imager comprising:
a casing holding a detector, a lens, a shutter disposed between the detector and the lens, and an electrical circuit operating the thermal imager at non-incendiary levels of electrical energy;
a motor operably connected to the shutter for moving the shutter between a first and a second position, the motor being a two-phase stepper motor, and
a source of electrical energy operably connected to the motor by the electrical circuit,
wherein the electrical circuit comprises one or more of a capacitor, a diode, and a resistor connected to the motor, and the one or more of the capacitor, diode, and resistor reduce one or more of a capacitance, voltage, and inductance of the electrical energy directed to the motor from the electrical circuit to below a non-incendiary level required for intrinsic safety.