Portable breath tester

• US 3,877,291 A
• Filed: 03/19/1973
• Issued: 04/15/1975
• Est. Priority Date: 08/15/1972
• Status: Expired due to Term

• Current Assignee: Alcohol Countermeasure Systems Corp.
• Original Assignee: Joseph P. Hoppesch, Stuart A. Schubert
• Inventors: Hoppesch, Joseph P., Schubert, Stuart A.
• Primary Examiner(s): Queisser, Richard C.
• Assistant Examiner(s): Kreitman, Stephen A.
• Application Number:
  US05/342,566
• Time in Patent Office: 757 Days
• Field of Search: 73/23,27R,421.5R 23/232R,232E,254R,254E 128/2.07 340/237R 324/71SN
• US Class Current: 73/23.3
• CPC Class Codes: G01N 27/122 Circuits particularly adapted therefor, e.g. linearising circuits
• CPC Class Codes: G01N 33/4972 Determining alcohol content for vehicle safety devices B60K28/06

Abstract

A breath tester, in two embodiments, employing an alcohol detecting element (e.g. a zinc oxide semiconductor element) which, prior to use, is purged by pumping ambient air across it and maintaining it at a higher than normal operating temperature. In use, after a purging period the air pumping is stopped and the detector heaters are turned off, while breath is directed to the detector and any resulting change in properties (conductivity/resistivity) is sensed and signaled. The first embodiment is largely manually operated and uses a meter to signal both the breath alcohol concentration, and also the purged state of the detecting element. The second embodiment is largely automatic, includes timers and interlocks to prevent misuse, and employs lights to signal its outputs ('"'"''"'"''"'"''"'"'fail,'"'"''"'"''"'"''"'"' for over one BAC level, '"'"''"'"''"'"''"'"'warn'"'"''"'"''"'"''"'"' for over a lower BAC level and '"'"''"'"''"'"''"'"'pass'"'"''"'"''"'"''"'"' for under that level) as well as its operational status ('"'"''"'"''"'"''"'"'power'"'"''"'"''"'"''"'"' on, '"'"''"'"''"'"''"'"'wait,'"'"''"'"''"'"''"'"' '"'"''"'"''"'"''"'"'ready,'"'"''"'"''"'"''"'"' '"'"''"'"''"'"''"'"'test'"'"''"'"''"'"''"'"'). Both embodiments may be battery powered and means for sensing and signaling the charge level on the batteries is disclosed.

Claims

1. The method of testing breath for alcohol content using a system including a semiconductor detecting unit, which unit has a semiconductor material exhibiting one electrical property after having been conditioned in an atmosphere essentially free of reducing substances and another property when exposed to a reducing atmosphere, such as breath entrained alcohol, and having means to heat the detector to at least two elevated temperatures, and means to sense the electrical property of the detector, comprising the steps of:

a. conditioning the detecting unit semiconductor material at a high temperature sufficient to rapidly diminish the alcohol from the space around the material for a period of time sufficient to cause the material to exhibit one electrical property state;

b. reducing the temperature to some lower value, and exposing a breath sample to the detector; and

c. sensiNg the change in the electrical property state which change is indicative of alcohol content.

2. The method of claim 1 wherein the semiconductor material is substantially enclosed in a cell and is heated by at least one heating element, comprising:

a. powering the heating element of the detecting unit to a temperature high enough to diminish any alcohol from the cell while causing the electrical conductance to become low;

b. reducing power to the detecting unit heating element to lower the detecting unit'"'"''"'"'s temperature;

c. exposing the detecting unit to a flow of breath while turning off all power to the heater of the detecting unit to allow the temperature of the detecting unit to fall; and

d. using the sensing means to sense the peak of the conductance of the detecting unit during and for a period after the flow of breath thereto and signaling this peak value as an indication of the breath alcohol concentration.

3. The method of claim 2 wherein during step (a) ambient air is flowed over the detecting unit.

4. The method of claim 2 wherein the detecting unit has two heaters embedded in the semiconductor material and both are turned on to achieve the higher temperature and only one is on to achieve the lower temperature.

5. A breath tester comprising:

a detector having a cell with a semiconductor detecting unit mounted therein, said unit being of the type that, after being conditioned in an essentially nonreducing atmosphere at an elevated temperature, decreases in resistivity in response to exposure to an alcohol containing atmosphere;

breath input means for allowing a gas sample to be supplied to said cell of said detector;

means for heating the detecting unit to at least two separate elevated temperatures;

pump means, for directing ambient air to and over the detecting unit;

sensing and signaling means for sensing the resistivity of said detecting unit and for signaling the sensed state of its resistivity; and

control means coupled to said sensing and signaling means, said pump means and said heating means for controlling said pump means flow of ambient air through the cell and for thereafter, stopping said pump means and controlling said heating means to lower the temperature of the detecting unit so that any resulting resistivity change may be sensed and signaled by said signaling means.

6. The breath tester of claim 5, wherein said control means controls said pump means to stop the flow over the detecting unit when the detecting unit resistivity reaches a preselected value.

7. The breath tester of claim 5, wherein said control means decreases the power supplied to said heating means when the detecting unit resistivity reaches a preselected value.

8. A breath tester comprising:

a detector having a semiconductor detecting unit of the type that, at an elevated temperature and after being conditioned in an essentially non-reducing atmosphere, decreases in resistivity in response to exposure to an alcohol containing atmosphere;

breath input means for allowing a gas sample to be supplied to said detector;

means for heating the detector to an elevated temperature;

pump means, for directing an essentially alcohol-free atmosphere containing oxygen to and over the detecting unit;

sensing and signaling means for sensing the resistivity of said detecting unit and for signaling the sensed state of its resistivity; and

control means coupled to said sensing and signaling means, said pump means and said heating means for controlling said pump means to purge the detector, and for thereafter stopping said pump means and controlling said heating means so that a breath sample may be then supplied to said breath input means and any resulting resistivity change is sensed annd signaled by said signaling means.

9. The breath tester of claim 8, wherein said control means controls said pump means to stop the flow over the detecting unit when the detecting unit resistivity reaches a prEselected value.

10. The breath tester of claim 8, wherein said control means decreases the power supplied to said heating means when the detecting unit resistivity reaches a preselected value.

11. The breath tester of claim 8, wherein said control means decreases the power supplied to said detecting unit when breath is received into the detector.

12. The method of testing breath for alcohol using a semiconductor material which can exhibit a marked drop in resistivity when exposed to at atmosphere containing alcohol or other reducing gases, comprising the steps of:

a. passing a stream of ambient air across the semiconductor material, while b. heating said material to an elevated temperature, for a period sufficient to cause the material to exhibit a high resistivity, and then;

c. after stopping steps (a) and (b) above, exposing the material to a breath sample and d. sensing and signaling any significant resultant drop in resistivity of the material, wherein said step (b) is performed by supplying electric power to resistance heaters, which power is supplied at a high rate in the presence of the air stream and at a lower rate during any period between the steps (b) and (c).

13. In a breath testing apparatus of the type having a semiconductor sensing means the method of testing a breath sample comprising the steps of:

a. heating the sensing means to an elevated temperature for a period sufficient to condition the element and b. thereafter allowing the sensing means to cool to a lower temperature and then c. exposing the sensing means to a breath sample.

14. The method of claim 13 wherein the sensing means is essentially SnO2 and said elevated temperature is approximately 340*C.

15. The method of claim 14 wherein the sensing means is cooled to below approximately 270*C as the lower temperature and in step (b) and during step (c) taking a reading of the conductivity of the sensing means exposed to the sample.

16. The method of testing a gas sample using a semiconductor detecting unit of the type that must be conditioned and to be maintained in the conditioned state must be maintained at an elevated first temperature, comprising the steps of:

a. conditioning the unit and keeping the unit at or about the first temperature until a gas sample is ready to be exposed to it;

b. lowering the temperature of the unit while at about the same time exposing the unit to the sample and, c. measuring and signaling the resulting change in conductivity of the unit.

17. The method of claim 16 wherein the semiconductor detecting unit is essentially SnO2, the elevated first temperature is approximately 270*C, and the temperature is lowered in step (b) to approximately the ambient temperature of the environment of use.