Apparatus for measuring the alcohol content in human breath
AssigneeC.S.S. Container Storage Service Establishment
InventorsBob Kok, Erhardt Krause
Life of this patent
Estimating the term…
Abstract
An individual blows into a chamber having a predetermined volume. In the chamber is mounted a gas cell including a heating conductor for catalytic burning of the alcohol and a probe at a predetermined distance from the heating conductor, both embedded in a ceramic porous shell. The lead-in conductor for the probe is connected to the base of a transistor in a threshold circuit which is responsive to the resistance of the gas cell which in turn decreases with increasing alcohol content. When the resistance is less than a predetermined resistance a relay in the transistor circuit operates, lighting an indicator lamp and, in one embodiment, deenergizing the ignition circuit of a vehicle in which the device is mounted.
Claims1
A portable hand-held apparatus for determining the alcohol content in the breath of a human subject, comprising, in combination, a gas chamber having an inlet into which the human subject can breathe and having at least one outlet;
- a low-voltage battery having first and second battery output terminals;
- first and second D.C. supply lines connected to said first and second battery output terminals;
- a gas cell mounted in said gas chamber and comprised of a porous semiconductor shell, a heating conductor embedded in said shell and connected to at least one of said supply lines, a probe embedded in said shell at a predetermined distance from said heating conductor, and a probe lead-in conductor connected to said probe, the resistance of said gas cell decreasing with increasing alcohol content of the gas present in said gas chamber;
- a milliammeter connected between said probe lead-in conductor and said first supply line for measuring and indicating the valve of the alcohol content in said gas;
- at least one transistor circuit each comprising a transistor and a relay, said transistor having a base connected to said probe lead-in conductor, an emitter connected to said first supply line, and a collector, said relay having a relay coil connected to said collector and said second supply line, at least one pair of relay contacts and at least one switch arm operated by said relay coil;
- at least one control circuit comprising a control lamp, one pair of said relay contacts being opened and closed by the corresponding relay switch arm and connected to cause said control lamp to light up when the current in the probe lead-in conductor exceeds a value corresponding to a predetermined alcohol content;
- and an adjustment resistor connected between said probe lead-in conductor and said first supply line and operative for adjusting the value of the probe lead-in conductor current at which said control lamp lights up, whereby a traffic officer or the like operating at night, in the rain, or in other low-visibility conditions, is informed by the control lamp that he should bother to take a precise alcohol content reading and is enabled by the milliammeter to thereafter actually take the reading.
Dependencies are inferred from the claim text.