Breath measurement instrument and breath alcohol interlock device incorporating same

• US 20030183437A1
• Filed: 03/28/2002
• Published: 10/02/2003
• Est. Priority Date: 03/28/2002
• Status: Active Grant

• Current Assignee: Ignition Interlock International
• Original Assignee: Ignition Interlock International
• Inventors: Mendoza, Joaquin L.
• Granted Patent: US 6,792,793 B2
• Time in Patent Office: Days
• US Class Current: 180/272
• CPC Class Codes: G01N 33/4972 Determining alcohol content for vehicle safety devices B60K28/06
• CPC Class Codes: Y10S 436/90 Breath testing
• CPC Class Codes: Y10T 436/204165 Ethanol

Abstract

A breath instrument using a combination of breath pressure, temperature, and humidity measurements to determine whether or not breath samples are human and properly delivered. Valid samples require maintenance of a threshold dynamic pressure of a sample being introduced for a predetermined time, a valid temperature of the sample and a valid humidity of the sample, wherein the range of valid sample temperatures is adjusted according to a measured sample humidity. Also disclosed is a breath alcohol instrument having an alcohol-specific fuel cell and a fuel cell circuit for generating a breath alcohol signal. Further disclosed is an interlock system for inhibiting operation of machinery such as a vehicle, and a method for screening breath samples and determining an alcohol content thereof.

Claims

1. A breath measurement instrument comprising:

(a) means for receiving a breath sample; and

(b) means for validating the sample, comprising;

(i) means for detecting the breath sample based on maintenance of a predetermined minimum dynamic pressure over a predetermined minimum sample interval;

(ii) means for determining a sample temperature of the sample;

(iii) means for determining a sample moisture content of the sample;

(iv) means for measuring at least one of an ambient temperature and an ambient humidity; and

(v) means for comparing the determined sample temperature and moisture content with a predetermined profile of valid temperatures and moisture contents, validation being blocked unless the determined temperature and moisture content is within the predetermined profile, wherein the predetermined profile includes a valid temperature range of the determined sample temperature and a valid humidity range of the determined sample humidity, at least one of the valid ranges being dependent on at least one of the ambient temperature and the ambient humidity.

2. The instrument of claim 1, wherein the means for receiving the breath sample comprises a tubular conduit having a mouthpiece extremity, the conduit defining a sample passage.

3. The instrument of claim 2, wherein the means for determining the sample temperature comprises a sample temperature sensor supported relative to the tubular conduit and projecting into the sample passage, and a sample temperature circuit having a sample temperature output, the sample temperature sensor and the sample temperature circuit together having a sample temperature response time.

4. The instrument of claim 3, wherein the valid range of the determined sample temperature is a first temperature range when the ambient temperature is within a predetermined ambient temperature range, the valid temperature range being otherwise a second temperature range, the first temperature range being within the second temperature range.

5. The instrument of claim 4, wherein the first temperature range is from approximately 32.5°

C. to approximately 36.5°

C., the second temperature range is from approximately 30.5°

C. to approximately 38.5°

C., and the ambient temperature range is from approximately 29.5°

C. to approximately 39.5°

.

6. The instrument of claim 3, wherein the valid range of the determined sample temperature is a first temperature range when the ambient temperature is not greater than a predetermined threshold ambient temperature, the valid temperature range being otherwise a second temperature range, the first temperature range being within the second temperature range.

7. The instrument of claim 6, wherein the threshold ambient temperature is approximately 80°

F. (26.6°

C.).

8. The instrument of claim 3, further comprising means for signifying at least an out-of-limit temperature, and an in-limit temperature of the breath sample.

9. The instrument of claim 3, wherein the sample temperature response time is not greater than approximately 1 second.

10. The instrument of claim 3, wherein the means for measuring ambient temperature comprises an ambient temperature sensor located externally of the sample passage and an ambient temperature circuit having an ambient temperature output, the ambient temperature sensor and the ambient temperature circuit together having an ambient temperature response time being greater than the sample temperature response time.

11. The instrument of claim 10, wherein the sample temperature response time is not greater than approximately 1 second and the ambient temperature response time is not less than approximately 1 minute.

12. The instrument of claim 2, wherein the means for determining humidity comprises a humidity sensor supported relative to the tubular conduit and projecting into the sample passage, and a humidity circuit having a sample humidity output.

13. The instrument of claim 12, wherein the valid range of the determined sample moisture content is a first moisture range when the ambient humidity is less than the sample moisture content, the valid moisture content range otherwise being a second moisture range, the first moisture range being within the second moisture range.

14. The instrument of claim 13, wherein the first moisture range is from approximately 67% RH to approximately 73% RH, and the second temperature range is from approximately 65% RH to approximately 75% RH.

15. The instrument of claim 12, further comprising means for signifying at least an out-of-limit humidity, and an in-limit humidity of the breath sample.

16. The instrument of claim 12, wherein the means for measuring the ambient humidity comprises means for sampling the sample humidity output as an ambient humidity output prior to receiving a breath sample.

17. The instrument of claim 1, wherein the valid range of the determined sample temperature is dependent on the ambient temperature and the valid range of the sample moisture content is dependent on the ambient humidity.

18. A breath alcohol instrument comprising the breath measurement instrument of claim 1 in combination with means for determining an alcohol content of the sample.

19. The breath alcohol instrument of claim 18, wherein the means for determining the alcohol content comprises an alcohol-specific fuel cell.

20. The breath alcohol instrument of claim 19, further comprising a fuel cell circuit for producing a breath alcohol signal, and means for compensating the breath alcohol signal in response to variations in one or more variables of the set consisting of ambient temperature, ambient pressure, sample temperature, and sample humidity.

21. The breath alcohol instrument of claim 20, wherein the means for receiving the breath sample comprises a tubular conduit having a mouthpiece extremity, the conduit defining a sample passage, wherein the means for measuring ambient temperature comprises an ambient temperature sensor located proximate the fuel cell and the tubular conduit for sensing a locally ambient temperature, the instrument further comprising a heater element in thermal communication with the tubular conduit, and wherein the means for compensating the breath alcohol signal comprises means for controllably powering the heater element in response to the ambient temperature sensor.

22. A breath alcohol interlock device for preventing use of a machine by an intoxicated operator, comprising the breath alcohol instrument of claim 18 in combination with an interlock circuit for disabling the machine except upon validation of a breath sample having an alcohol content below a predetermined amount.

23. A breath alcohol interlock device for preventing use of a machine by an intoxicated operator, comprising:

(a) means for receiving a breath sample, comprising a tubular conduit having a mouthpiece extremity, the conduit defining a sample passage;

(b) means for validating the sample, comprising;

(i) a pressure transducer including an actuator projecting into the sample passage and apparatus converting for generating a sample pressure signal in response to dynamic gas pressure against the actuator for detecting the breath sample based on maintenance of a predetermined minimum dynamic pressure over a predetermined minimum sample interval;

(ii) means for determining a sample temperature of the sample, comprising a sample temperature sensor supported relative to the tubular conduit and projecting into the sample passage, and a sample temperature circuit having a sample temperature output;

(iii) means for determining a sample moisture content of the sample, comprising a humidity sensor supported relative to the tubular conduit and projecting into the sample passage, and a humidity circuit having a sample humidity output, the humidity sensor and humidity circuit output being operative for providing an ambient humidity measurement prior to receipt of the breath sample;

(iv) an ambient temperature sensor located proximate the tubular conduit and an ambient temperature circuit responsive thereto and having an ambient temperature output;

(v) a heater element in thermal communication with the tubular conduit; and

(vi) a processor for comparing the determined sample temperature and moisture content with a predetermined profile of valid temperatures and moisture contents in response to the sample temperature and humidity outputs and the ambient temperature output, validation being blocked unless the sample temperature and the sample moisture content are within the predetermined profile, wherein the predetermined profile includes a valid range of the determined sample temperature that is dependent on the ambient temperature and a valid humidity range of the sample moisture content that is dependent on the ambient humidity;

(c) an alcohol-specific fuel cell and a fuel cell circuit for producing a breath alcohol signal, the processor being operative for activating the heater element in response to the ambient temperature sensor to selectively maintain a predetermined minimum ambient temperature proximate the sample passage for compensating the breath alcohol signal in response to ambient temperature, the processor also determining an alcohol content of the sample; and

(d) an interlock circuit for disabling the machine in response to the processor except upon validation of a breath sample having an alcohol content below a predetermined amount.

24. A method for screening breath samples and determining an alcohol content thereof, comprising:

(a) receiving a breath sample;

(b) validating the sample, comprising;

(i) determining a sample temperature of the sample;

(ii) determining a moisture content of the sample;

(iii) measuring at least one of an ambient temperature and an ambient humidity;

(iv) comparing the determined sample temperature and moisture content with a predetermined profile of valid temperatures and moisture contents; and

(v) blocking the validation unless the determined temperature and moisture content is within the predetermined profile, wherein the predetermined profile includes a valid temperature range of the sample temperature that is dependent on the ambient temperature, and a valid determined sample moisture content that is dependent on ambient humidity;

(c) determining an alcohol content of the sample, comprising producing a breath alcohol signal responsive to the alcohol content of the sample; and

(d) compensating the breath alcohol signal in response to variations in one or more variables of the set consisting of ambient temperature, ambient pressure, sample temperature, and sample humidity.

25. The method of claim 24, wherein the means for determining the alcohol content comprises an alcohol-specific fuel cell.