Particulate matter detection circuit and filter processing device
AssigneeFujitsu Limited
InventorTatsuya Hirose
Life of this patent
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Abstract
A particulate matter detection circuit includes, a negative resistance circuit that couples to a first antenna inserted in a housing accommodating a first filter that filters an exhaust gas, couples to a second antenna inserted in the housing via a matching circuit that performs an impedance matching and a second filter that narrows the frequency band of a passing signal, and oscillates at a resonance frequency of the housing, and a detection circuit that outputs a voltage value corresponding to a signal strength of a radio wave received by a third antenna or the second antenna inserted in the housing. The resonance frequency of the housing varies depending on an amount of matter adhered to the first filter.
Claims7
A particulate matter detection circuit comprising:
- a negative resistance circuit configured to:
- couple to a first antenna arranged in a housing accommodating a first filter that filters an exhaust gas,
- couple to a second antenna arranged in the housing via a matching circuit that performs an impedance matching and a second filter that narrows the frequency band of a passing signal, and
- oscillate at a resonance frequency of the housing, the resonance frequency of the housing varying depending on an amount of matter adhered to the first filter;
- and
- a detection circuit configured to output a voltage value corresponding to a signal strength of a radio wave received by a third antenna or the second antenna inserted in the housing.
A filter processing device comprising:
- a particulate matter detection circuit including a negative resistance circuit and a detection circuit;
- and
- a signal processing circuit,
- wherein the negative resistance circuit is configured to:
- couple to a first antenna arranged in a housing accommodating a first filter that filters an exhaust gas,
- couple to a second antenna arranged in the housing via a matching circuit that performs an impedance matching and a second filter that narrows the frequency band of a passing signal, and
- oscillate at a resonance frequency of the housing, the resonance frequency of the housing varying depending on an amount of matter adhered to the first filter,
- wherein the detection circuit is configured to output a voltage value corresponding to a signal strength of a radio wave received by a third antenna or the second antenna inserted in the housing, and
- wherein the signal processing circuit is configured to measure the voltage value and the frequency of an output signal of the negative resistance circuit and output results of the measurement.
Dependencies are inferred from the claim text.