Modulation Responsive Anti-evasion System For Breath Testers

Abstract

An anti-evasion system is disclosed for breath alcohol testers including a sound transducer and filter network that distinguishes between the presence and absence of human modulation of the breath sample (such as humming) and prevents a gas sample not obtained in conjunction with such modulation from indicating a "pass".

Description

FIELD OF THE INVENTION

The present invention relates to an anti-deception system for breath alcohol testers.

REFERENCE TO RELATED APPLICATIONS

The present invention finds special utility in the environment of use of the breath testers described and claimed in the following U.S. patent applications:

Serial No. Filing Date Title Inventors 136,921 April 23, 1971 Vehicle Breath D. Collier, Testing System J. Hoppesch and A. Mamo 136,778 April 23, 1971 Breath Testing D. Collier, System J. Hoppesch and A. Mamo

BACKGROUND OF THE INVENTION

The general background is given in the above applications. The particular problem that this invention deals with is that of evasion of the unsupervised tester, such as that disclosed in Ser. No. 136,921, by the subject using a bellows or bag of air instead of blowing his breath into the tester.

SUMMARY OF THE INVENTION

An anti-evasion system for use with a breath tester constructed in accordance with the present invention includes a transducer positioned to receive sound waves transmitted at the breath input of the tester and transforms those sound waves into an electrical signal, means (e.g., a filter) coupled to the transducer for distinguishing between the presence and absence of audio frequencies and control means for preventing passing of the test in the absence of pre-selected frequencies.

Additional features of the present invention which are believed to be novel are set forth hereinafter. The invention, together with the further advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawings, in the several figures of which like reference numerals identify like elements.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a breath input unit, of a breath tester incorporating the present invention, with parts broken away to show interior parts;

FIG. 2 is a block diagram of the inventive system; and

FIG. 3 is a detailed diagram, partly in block form and partly in circuit form, of a part of the system of FIGS. 1 and 2.

DETAILED DESCRIPTION

In FIG. 1 a breath input unit 10 is shown having, downstream of its breath opening 12, in accordance with the present invention, a sound transducer 14 connected by wires 16 to the remainder of the inventive system. This sytem is illustrated in FIG. 2 and generally designated 20. The output signal of transducer 14 is amplified by an amplifier 18 and fed to a filter 22 which serves as means for distinguishing between the presence and absence of required frequencies. For example, the filter may substantially attenuate audio frequency signals below 50 hz and above 500 hz and a low hum be required of the user of the breath tester. In this case absence of such a hum would mean that essentially no signal is passed by the filter 22. The signals passed by filter 22 are amplified by the amplifier 24 and coupled to a control circuit 26 which serves to prevent a "pass" output signal from being produced by the tester.

The circuit 26 preferably includes an indicator 28, such as a light, which indicates the presence of a proper sound.

Reference should be had to the aforementioned Ser. No. 136,921 application for the general system in which this system 20 may operate that system includes a pressure switch and timer. A portion of FIG. 5 thereof is depicted in FIG. 3 hereof. Referring to FIG. 3, it can be seen that the blowing timer 62 and pressure switch 60 are unchanged, but that the base of that switch is, in accordance with this invention, connected to ground through the circuit 26, specifically through the collector-emitter circuit of an NPN transistor 26A. The collector of transistor 26A is also connected to one side of the lamp 28 whose other side is connected by a line 260 to the line connecting K4B and K2 (a convenient source of positive potential).

The base of transistor 26A is connected through a parallel-connected resistor 26B and capacitor 26C to ground and through a diode 26D to the signal from the amplifier 24.

The remainder of the circuit and operation of the embodiment of the 136,778 application may be unchanged, and for completeness of this disclosure the description and drawings of the aforementioned Ser. No. 136,921 patent application are hereby incorporated by reference under the procedure approved by the Commissioner of Patents in 34 Federal Register 833 on Jan. 18, 1969 (859 Official Gazette 346).

The presence of the proper pressure for a sufficient length of time (e.g., 5 seconds) is used to obtain a sample of deep lung breath from a human user. The present exemplary system adds the requirement that the anti-evasion output signal from circuit 26 be also present for that period. In the absence of both such signals for the period the test is aborted and no pass signal may be obtained.

Although here illustrated as a simple filter more elaborate means may be employed and more complex sound signals required without departing from at least the broader aspects of the present invention. For example, interruptions for preselected intervals (e.g., as indicated by another signal light) might be added.

While a particular embodiment of the invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspects and, therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of the invention.

Claims

1. A breath tester system for administering a test to a human subject to evaluate the alcohol concentration in the subject's breath, comprising:

a breath tester;

a breath input unit connected to the tester, such that the subject can blow breath into said input unit for evaluation by the tester;

transducer means, positioned within said breath input unit, for translating received audio-frequency sounds into electrical signals;

filter means, coupled to said transducer, for passing only electrical signals within a preselected band of frequencies as determined by the filter characteristics; and

control circuit means, coupled both to said filter and to said breath tester, operative to prevent the breath tester from indicating the subject has passed the test in the absence of receipt from said filter of signals

2. A breath tester system as claimed in claim 1, and further comprising an indicator means, coupled to said control circuit, for signalling receipt by said control circuit of a signal within said preselected band of frequencies.