Abstract A gas-alarm device comprising a gas-detecting portion including an a.c. or d.c. power source, a semiconductor-type gas-detecting element consisting of a gas sensitive semiconductor substance, and an output resistor all connected in series so that a voltage depending on the concentration of the gas appears across the output resistor; a circuit portion for converting said voltage across the output resistor of the gas-detecting portion into a d.c. voltage, a saw-tooth wave oscillating portion including a capacitor, a current limiting resistor series connected to said capacitor, both connected across said d.c. voltage, and a discharge tube, such as a neon lamp, having a negative resistance characteristic and connected in parallel with said capacitor; and a sound emitting device, such as a speaker; whereby the frequency and intensity of the alarm output sound are made variable depending on the concentration of the gas and the adjustment of said current limiting resistor as desired.
Inventors
👤 Riichiro Kasahara
Bibliographic Details
Application Number—
JurisdictionUS
Data Sourcegoogle_patents
Last Synchronized2026-10-24 17:56
CPC Classifications
G; G08; G08B; G08B17/00; G08B17/10; G08B17/117
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
154 words
In a gas-alarm device including a gas-detecting portion including a semiconductor-type gas-detecting element consisting of a gas-sensitive semiconductor substance having at least one electrode embedded therein and an output resistor series connected to said electrode, and a power source connected across the series combination of said element and said resistor so that a voltage depending on the concentration of the gas appears thereacross, the improvement comprising a sounding device for producing an alarming signal and a saw-tooth wave oscillator portion connected to said sounding device and responsive to said voltage dependent on the concentration of the gas, including a capacitor, a current limiting resistor series connected to said capacitor, and a discharge tUbe having a negative-resistance characteristic connected in parallel to said capacitor, so that the intensity of the alarming sound emitted by said sounding device is made variable depending on the concentration of the gas detected in said gas-detecting portion of the device.
Claim 2
Dependent Claim
154 words
In a gas-alarm device including a gas-detecting portion including a semiconductor-type gas-detecting element consisting of a gas-sensitive semiconductor substance having at least one electrode embedded therein and an output resistor series connected to said electrode, and a power source connected across the series combination of said element and said resistor so that a voltage depending on the concentration of the gas appears thereacross, the improvement comprising a sounding device for producing an alarming signal and a saw-tooth wave oscillator portion connected to said sounding device and responsive to said voltage dependent on the concentration of the gas, including a capacitor, a current limiting resistor series connected to said capacitor, and a discharge tUbe having a negative-resistance characteristic connected in parallel to said capacitor, so that the intensity of the alarming sound emitted by said sounding device is made variable depending on the concentration of the gas detected in said gas-detecting portion of the device.
Claim 3
Dependent Claim
28 words
A gas-alarm device according to claim 1, wherein said gas-detecting element comprises a gas sensitive semiconductor substance, a heater electrode and another electrode embedded in said semiconductor substance.
Claim 4
Dependent Claim
65 words
A gas-alarm device according to claim 2 wherein both said element and said resistor are connected in series across an a.c. power source so that an a.c. voltage depending on the concentration of the gas appears across said output resistor, and said gas-detecting portion includes a rectifying and smoothing circuit for converting said a.c. voltage appearing across the output resistor into a smoothed d.c. voltage.
Claim 5
Dependent Claim
62 words
A gas-alarm device according to claim 2 wherein both said element and resistor are connected in series across a d.c. power source so that a d.c. voltage depending on the concentration of the gas appears across said output resistor, and the series connected current limiting resistor and said capacitor of said saw-tooth wave oscillator are connected in series across said output resistor.