Exercise System With Headphone Detection Circuitry

Abstract

Described is a circuit arrangement for detection of a tone whose presence indicates insertion of a headphone plug into a jack. The circuit includes a receptacle having contacts configured to receive a plug inserted into the receptacle, a current sense circuit, an amplifier coupled to the current sense circuit and a band pass filter coupled to an output of the amplifier, the band pass filter configured to pass a signal having a frequency in a range of about 2 Hz to 20 Hz. Circuitry converts the passed signal into a digital signal to provide an input signal to a controller to indicate that a headphone plug was inserted into the receptacle.

1 . A circuit arrangement, comprises:
 a current sense circuit configured to couple between a signal source and a plug receptacle;   a voltage amplifier coupled to the current sense circuit;   a band pass filter coupled to an output of the amplifier, the band pass filter configured to pass a signal having a frequency in a range of about 2 Hz to 20 Hz; and   circuitry to convert the passed signal into a digital signal to provide an input signal to a controller to indicate the presence of a plug inserted into the plug receptacle.   
     
     
         2 . The circuit arrangement of  claim 1 , wherein the circuitry to convert further comprises:
 a rectifier circuit coupled to the output of the band pass filter to convert the signal having the frequency into a DC signal.   
     
     
         3 . The circuit arrangement of  claim 2 , wherein the circuitry to convert further comprises:
 a comparator circuit coupled to the rectifier circuit.   
     
     
         4 . The circuit arrangement of  claim 3 , wherein the circuitry to convert further comprises:
 a driver circuit.   
     
     
         5 . The circuit arrangement of  claim 1 , wherein the pass band of the filter is 2 Hz to 20 Hz. 
     
     
         6 . The circuit arrangement of  claim 1 , wherein the pass band of the filter is a range of about 8 Hz to 18 Hz. 
     
     
         7 . The circuit arrangement of  claim 1 , wherein the pass band of the filter is about 15 Hz. 
     
     
         8 . The circuit arrangement of  claim 1 , further comprising:
 a receptacle having contacts configured to receive a plug inserted into the receptacle.   
     
     
         9 . A system comprises:
 a cardio exercise machine having a first receptacle having contacts configured to receive a plug inserted into the first receptacle, with the first receptacle affixed to a portion of the cardio exercise machine, and having a second receptacle that receives input audio from an audio source;   a controller that superimposes a sub-audio signal on the input audio and feeds the superimposed sub-audio signal on the audio to the first receptacle;   a plug insertion detector circuit coupled to the first receptacle, the plug detection circuit comprising:
 a current sense circuit coupled to the first receptacle to receive the superimposed sub-audio signal on the audio; 
 an amplifier coupled to the current sense circuit; 
 a band pass filter coupled to an output of the amplifier, the band pass filter configured to pass a signal having a frequency in a range of about 2 Hz to 20 Hz; and 
 circuitry to convert the passed signal into a digital signal to provide an input signal to the controller to indicate the presence of a plug inserted into the receptacle. 
   
     
     
         10 . The system of  claim 9  wherein the controller is configured to receive the digital signal to control generation of audio direction to a user of the cardio exercise machine, and to
 generate audio direction at least partially based on at least one of the user's operation of the cardio exercise machine and the selected workout program and the assertion of the digital signal. 
 
     
     
         11 . The system of  claim 9  wherein the exercise machine comprises a treadmill, stationary bicycle, stair-climber, elliptical trainer, ski-trainer, or rowing machine. 
     
     
         12 . The system of  claim 9  wherein the pass band of the filter is 2 Hz to 20 Hz. 
     
     
         13 . The system of  claim 9  wherein the pass band of the filter is a range of about 8 Hz to 18 Hz. 
     
     
         14 . The system of  claim 9  wherein the pass band of the filter is about 15 Hz. 
     
     
         15 . The system of  claim 9  wherein the circuitry to convert further comprises:
 a rectifier circuit coupled to the output of the band pass filter to convert the output into a DC signal; 
 a comparator circuit coupled to the rectifier circuit that produces an assertion of a detected signal when the signal from the rectifier circuit exceeds a fixed reference value to indicates that the superimposed signal in the pass band of about 2 Hz to 20 Hz was received by the plug detection circuit. 
 
     
     
         16 . A machine, comprises:
 a user interface module having a first receptacle configured to receive a plug inserted into the first receptacle, with the first receptacle affixed to a portion of the machine and a second receptacle that receives input audio from an audio source;   a controller that superimposes a sub-audio signal on the received audio and feeds the received audio with the superimposed sub-audio signal to the first receptacle;   a plug insertion detector circuit coupled to the first receptacle, the plug detection circuit comprising:
 a current sense circuit coupled to the first receptacle to receive the superimposed sub-audio signal on the audio; 
 an amplifier coupled to the current sense circuit; 
 a band pass filter coupled to an output of the amplifier, the band pass filter configured to pass a signal having a frequency in a range of about 2 Hz to 20 Hz; and 
   circuitry to convert the passed signal into a digital signal to provide an input signal to the controller to indicate the presence of a plug inserted into the receptacle.   
     
     
         17 . The machine of  claim 16  wherein the second receptacle is configured to receive audio from an audio source that is internal to the machine. 
     
     
         18 . The machine of  claim 16  wherein the second receptacle is configured to receive audio from user supplied audio source. 
     
     
         19 . The machine of  claim 16  wherein the second receptacle is configured to receive audio from a remote audio source. 
     
     
         20 . The machine of  claim 16  wherein the plug insertion detector circuit further comprises:
 a rectifier circuit coupled to the output of the band pass filter to convert the output into a DC signal; 
 a comparator circuit coupled to the rectifier circuit that produces an assertion of a detected signal when the signal from the rectifier circuit exceeds a fixed reference value to indicates that the superimposed signal in the pass band of about 2 Hz to 20 Hz was received by the plug detection circuit.