PULSE STRETCHER FOR A RECEIVER OF A PNEUMATIC TIRE LOW PRESSURE MONITORING AND WARNING SYSTEM

• US 3,835,451 A
• Filed: 09/15/1972
• Issued: 09/10/1974
• Est. Priority Date: 09/15/1972
• Status: Expired due to Term

• Current Assignee: Donald E. Church
• Original Assignee: Donald E. Church
• Inventors: Church, Donald E.
• Primary Examiner(s): Waring, Alvin H.
• Application Number:
  US05/289,540
• Time in Patent Office: 725 Days
• Field of Search: 340/58 325/15,111,117 200/61.22,61.25
• US Class Current: 340/447
• CPC Class Codes: B60C 23/0433 Radio signals

Abstract

An electrical apparatus provides a reliable indication which is readily identifiable once a plurality of useable electrical signals are supplied thereto as a result of a low pressure condition in a pneumatic tire of an associated vehicle. The apparatus employs an electrical device which increases the effective time duration of a useable signal and an indicator which provides the indication during the increased time duration of the useable signal and such indicator operates to automatically cease to provide an indication after a time period to thereby define the identifiable indication by a repeated activation of the indicator.

Claims

1. An electrical apparatus for providing a reliable indication when a repetitive series of effective output pulse signals of short time duration are supplied thereto as the result of a low pressure condition in a pneumatic tire of as associated vehicle, said effective pulses being separated by ineffective intervals of much greater time duration than the effective pulses, said electrical apparatus comprising a first electrical device which extends the time periods of said effective output pulses from said electrical apparatus indefinitely when activated by one of said short duration effective pulses;

indicating means displaying an inadequate indication when the pulse signal of short time duration is used to control said indicating means directly; and

a second electrical device associated with said indicating means for terminating the extended effective output pulses generated by said first electrical device after a preselected time interval and thereby generating effective control pulses of much longer time duration than the short time duration effective output pulses.

2. In a pneumatic tire low pressure monitoring and warning system having;

means sensing a low pressure condition in a pneumatic tire supported on an associated vehicle by a rotatable support;

a transmitter carried off center by said rotatable support and being rotatable therewith at a distance from the central axis of rotation, said transmitter being actuated by said sensing means and generating output signals at a radio frequency in response to said low pressure condition;

a receiving antenna attached at a fixed position adjacent said tire within the near field of said transmitter, the coupling between said transmitter and said receiving antenna being subject to variations resulting from differences in distance, orientation and shielding between said transmitter and said receiving antenna;

said receiving antenna receiving usable radio frequency signals only during a relatively small portion of each complete rotation of said transmitter therepast when the coupling is maximized;

a receiver; and

means operatively connecting said receiving antenna to said receiver;

said transmitted radio frequency signal generating in said receiver a discontinuous control signal comprising a repetitive series of effective pulse signals of short duration, said effective pulses being separated by ineffective intervals of much greater time duration than said effective pulses;

the improvement comprising a first electrical device which extends the time periods of the effective output pulses indefinitely when activated by one of said short duration effective pulses;

indicating means providing an inadequate indication when said pulse signal of short time duration is used to control said indicating means directly; and

a second electrical device associated with said indicating means for terminating said extended effective output pulses generated by said first electrical device after a preselected time interval and thereby generating effective control pulses of much longer time duration than the short time duration effective pulses wherein the long duration control pulses control said indicating means to thereby define the identifiable indication by a repeated activation of said firSt electrical device.

3. An apparatus as set forth in claim 1 in which said first electrical device is an SCR.

4. An apparatus as set forth in claim 3 in which said indicating means is a filament lamp.

5. An apparatus as set forth in claim 4 in which said second electrical device is a bimetallic strip, and in which said indicating means is a flasher filament lamp wherein said second electrical device is combined with said indicating means.

6. In a pneumatic tire low pressure monitoring and warning system as set forth in claim 2 the further improvement wherein said first electrical device is an SCR.

7. In a pneumatic tire low pressure monitoring and warning system as set forth in claim 6 the further improvement wherein said indicating means is a filament lamp.

8. In a pneumatic tire low pressure monitoring and warning system as set forth in claim 7 the further improvement wherein said second electrical device is a bimetal strip and in which said indicating means is a flasher filament lamp wherein said second electrical device is combined with said indicating means.

9. In a pneumatic tire low pressure monitoring and warning system as set forth in claim 8 the further improvement comprising an RC filter and a current limiting resistor connected to said SCR.

10. In a pneumatic tire low pressure monitoring and warning system as set forth in claim 6 in which each of said transmitters comprises a self-pulsed oscillator.