Abstract: A method for forming a conducting metal layer on an inorganic substrate is to heat the inorganic substrate accommodated in a vacuum vessel of sputtering device in which a high degree of vacuum is attained, to lead into the vacuum vessel a discharge gas as regulated to be at a predetermined pressure, to apply a high frequency power with the inorganic substrate made as a target, to interrupt the power to regulate the discharge gas to be at a predetermined pressure relatively low, and to apply DC power with a conductive metal member made as a target for thereby forming the conducting metal layer on the inorganic substrate. The metal layer formation on the inorganic substrate is thereby simplified enough for improving the producibility in industrial scale and is still capable of attaining a satisfactory bonding strength between the metal layer and the substrate.

Abstract: A gas detector for detecting the leak of fuel gases, such as hydrogen gas, methane gas, butane gas, with improved reliability in detecting the gas leak. Said gas detector includes a main gas sensing element showing the change in resistance to target gases, such as methane, butane, hydrogen, as well as to non-target gases, such as alcohol, steam, smoke; an auxiliary gas sensing element showing change in resistance rather to non-target gas than to target gas; the first comparator receiving the output induced by resistance change in main gas sensor, as input; the second comparator with reference voltage set at lower level than that for the first comparator; and a gate circuit for blocking the alarm driving signal of the second comparator by the output induced by resistance change in auxiliary gas sensor. The output obtained from either said gate circuit or the first comparator is used for alarm driving signal of alarm circuit.

Abstract: A gas detector comprising a main gas sensing element showing the resistance change to both the detection target gases, such as methane, butane, hydrogen gases, and non-target gases such as alcohol steam, smoke; an auxiliary gas sensing element showing the resistance change primarily to non-target gases along; the first comparator to which the output based on the resistance change of main gas sensing element is received as input in parallel form; the second comparator with lower reference electric power than that of the first comparator; a gate circuit to cut off the alarm actuating signal from the second comparator by means of output induced by the resistance change of auxiliary gas sensing element. Either the output from said gate circuit or the output from said first comparator is used for alarm actuating signal of alarm circuit.