Fault detector for igniter testing using high frequency noise

Claim 3

A method of testing electrical resistance type igniters according to claim 1, comprising the steps of: filtering the operating voltage; and amplifying the generated high frequency noise before comprising the level of the noise with the reference level.

Claim 4

A method of testing electrical resistance type igniters according to claim 1, comprising the step of: activating an indicator in response to a high frequency noise level below the reference level as a positive indication of an operationally non-faulty igniter.

Claim 7

Apparatus for testing electrical resistance type igniters for defects, comprising: means connecting an igniter to an operational voltage supply to generate high frequency noise across a defective igniter; an impedance electrically connected to the igniter to sample the high frequency noise; an amplifier; a high pass filter connected between said impedance and said amplifier for receiving and filtering the noise for amplification; a signal level detection means connected to said amplifier for comparing the signal level of the high frequency noise with a reference signal level and operable to provide a first signal representing an igniter which is substantially free of defects when the noise level is below the reference level and a second signal representing an operationally defective igniter when the noise level is above the reference level; first and second indicators respectively representing defect free and defective igniters; and switch means connected between said signal level detection means and said indicators and operated by said first and second signals, respectively, to energize the respective first and second indicators.

Claim 8

Apparatus for testing electrical resistance type igniters for defects, comprising: means connecting an igniter to an operational voltage supply to generate high frequency noise across a defective igniter; an impedance electrically connected to the igniter to sample the high frequency noise; an amplifier; a high pass filter connected between said impedance and said amplifier for receiving and filtering the noise for amplification; a signal level detection means connected to said amplifier for comparing the signal level of the high frequency noise with a reference signal level and operable to provide a first signal representing an igniter which is substantially free of defects when the noise level is below the reference level and a second signal representing an operationally defective igniter when the noise level is above the reference level; first and second indicators respectively representing defect free and defective igniters; and switch means connected between said signal level detection means and said indicators and operated by said first and second signals, respectively, to energize the respective first and second indicators.

Claim 9

Apparatus for testing electrical resistance type igniters for operational faults, comprising: means for applying an operating voltage to an igniter to cause the generation of high frequency noise by a faulty igniter; an impedance connected to the igniter for sampling signals developed across the igniter; filter means connected to said impedance for passing high frequency noise; amplifying means connected to said filter means for amplifying the signal received therefrom; signal level detector means connected to said amplifying means for desensitizing the circuit with respect to high frequency noise signals below a reference level; and signal means connected to said signal level detector means and operative to indicate a faulty igniter.

Claim 10

Apparatus for testing electrical resistance type igniters for operational faults, comprising: means for applying an operating voltage to an igniter to cause the generation of high frequency noise by a faulty igniter; an impedance connected to the igniter for sampling signals developed across the igniter; filter means connected to said impedance for passing high frequency noise; amplifying means connected to said filter means for amplifying the signal received therefrom; signal level detector means connected to said amplifying means for desensitizing the circuit with respect to high frequency noise signals below a reference level; and signal means connected to said signal level detector means and operative to indicate a faulty igniter.

Claim 11

Apparatus according to claim 6, wherein said means for applying an operating voltage comprises a switch connected between the igniter and an electrical supply.

Claim 12

Apparatus according to claim 6, wherein said impedance comprises a resistor connected to the igniter and to said filter means.

Claim 13

Apparatus according to claim 6, wherein said signal level detector means comprises: a comparator circuit including an operational amplifier and a variable voltage divider, with a first input to the operational amplifier connected to said amplifying means and a second input to the operational amplifier connected to said variable voltage divider, said variable voltage divider providing a reference signal level at said second input, and said comparator circuit operative to provide a first signal in response to a signal level at said first input that is below the reference level and to provide a second signal in response to a signal level at said first input that is above the reference level; and said signal means comprises: first and second indicators for respectively indicating non-faulty and faulty igniters; and switch means connected between said comparator circuit and said indicators, said switch means operated by said first signal to energize said first indicator and by said second signal to energize said second indicator.

Claim 14

Apparatus according to claim 9, wherein said switch means comprises: a memory circuit connected between said comparator circuit and said indicators.

Claim 15

Apparatus according to claim 10, wherein said switch means further comprises: means for operating said memory circuit to a state wherein said first indicator is normally energized.

Claim 16

Apparatus according to claim 10, wherein each of said indicators comprises: a lamp; and the switch means includes a lamp driver connected between said memory circuit and said lamp.

Claim 17

Apparatus according to claim 10, wherein said second indicator comprises: an audible alarm means connected to said switch means.

Claim 18

Apparatus for testing electrical resistance type igniters for operational defects, comprising: means for connecting the igniter to an electrical supply for providing an operational voltage to the igniter, a defective igniter being responsive to the operational voltage to generate high frequency noise; an impedance connected to the igniter to sample signals developed across the igniter; a high pass filter connected to said impedance for passing high frequency noise; an amplifier connected to said high pass filter to amplify signals passed thereby; a comparator circuit including a first input connected to said amplifier, a second input, and a reference signal level circuit connected to said second input, said comparator circuit being operable to provide first and second signals when the signal level at said first input is above and below, respectively, the reference level; an inverter connected to said comparator circuit to invert the first and second signals; first and second indicating means including first and second drivers and first and second lamps connected to respective first and second drivers for identifying defective and sound igniters, respectively; a latching circuit including a first input and first and second outputs, said first input connected to said inverter, said first and second outputs connected to said first and second drivers, respectively, said latching circuit being responsive to the inverted first and second signals to operate said first and second drivers, respectively.

Claim 19

Apparatus for testing electrical resistance type igniters for operational defects, comprising: means for connecting the igniter to an electrical supply for providing an operational voltage to the igniter, a defective igniter being responsive to the operational voltage to generate high frequency noise; an impedance connected to the igniter to sample signals developed across the igniter; a high pass filter connected to said impedance for passing high frequency noise; an amplifier connected to said high pass filter to amplify signals passed thereby; a comparator circuit including a first input connected to said amplifier, a second input, and a reference signal level circuit connected to said second input, said comparator circuit being operable to provide first and second signals when the signal level at said first input is above and below, respectively, the reference level; an inverter connected to said comparator circuit to invert the first and second signals; first and second indicating means including first and second drivers and first and second lamps connected to respective first and second drivers for identifying defective and sound igniters, respectively; a latching circuit including a first input and first and second outputs, said first input connected to said inverter, said first and second outputs connected to said first and second drivers, respectively, said latching circuit being responsive to the inverted first and second signals to operate said first and second drivers, respectively.

Claim 20

ApparatUs according to claim 14, wherein said latching circuit includes a second input, and further comprising: a low voltage power supply connected to said latching circuit, to said inverter, and to said indicating means; and a preset circuit connected to said second input to preset said latching circuit to cause energization of said second lamp upon the application of low voltage power from said supply.

Claim 21

Apparatus according to claim 14, wherein said impedance comprises a resistor.

Claim 22

Apparatus according to claim 14, wherein said first indicating means comprises an audible alarm device connected to and operated by said first driver.

Claim 23

Apparatus for testing for a faulty connection of an electrical resistance type igniter, comprising: means for providing power to an igniter under test to cause the generation of high frequency electrical noise by a faulty igniter; detecting means electrically connected to said igniter for detecting the presence of high frequency electrical noise; and signal means responsive to the detecting means for indicating a faulty condition of the igniter under test.

Claim 24

Apparatus for testing for a faulty connection of an electrical resistance type igniter, comprising: means for providing power to an igniter under test to cause the generation of high frequency electrical noise by a faulty igniter; detecting means electrically connected to said igniter for detecting the presence of high frequency electrical noise; and signal means responsive to the detecting means for indicating a faulty condition of the igniter under test.

Claim 25

The testing apparatus defined in claim 18 wherein: the detecting means comprises filter means for passing only high frequency noise, a resistor connected between the igniter and the filter means in series relationship with the igniter and in parallel relationship with the filter means, amplification means electrically connected to the filter means for amplifying the high frequency electrical noise passed by the filter means, and comparator means electrically connected to the amplification means for providing a reference signal level, comparing the level of the amplified high frequency noise with the reference signal level, and passing only amplified high frequency noise above the reference level; and the signal means comprises switch means including a memory circuit electrically connected to the comparator means and responsive to the comparator means, and indicator means responsive to the switch means for demonstrating a faulty condition of the igniter under test.