Automatic turn-on and turn-off control for battery-powered headsets

Abstract

Some workers wear headsets to protect their hearing from loud persistent noises, such as airplane engines and construction equipment. These headsets are generally passive or active, with the active ones including ear speakers and automatic noise-reduction (ANR) circuitry to cancel or suppress certain types of loud persistent noises. One problem with active headsets, particulary those that are battery-powered, concerns battery life. Workers often take the headset off or store them without turning them off and thus wasting costly battery life. Accordingly, the inventor devised active headsets with automatic turn-on and/or turn-off circuits. One exemplary embodiment senses a condition of the headsets, for example, the light, pressure, or temperature within one earcup, and then turns the headset on or off in response to the sensed condition.

1 - 8 . (Canceled)  
     
     
         9 . An active headset having at least two operating states and comprising: 
 one or more earcups;    means for sensing a condition that is within at least one of the earcups; and    means, responsive to a perceived absence of the condition, for changing the operating state of the headset.    
     
     
         10 . The active headset of  claim 9  wherein the condition is inaudible.  
     
     
         11 . The active headset of  claim 10  wherein the means for sensing a condition within at least one of the earcups includes a microphone coupled to a bandpass filter, the bandpass filter coupled to a threshold detector, the threshold detector coupled to a processor, and the processor coupled to a power switch.  
     
     
         12 . The active headset of  claim 9  wherein one of the two operating states is an on state and the other is an off or standby state, and wherein the means for changing the operating state of the headset is responsive to the sensed condition to change from the on state to the off or standby state.  
     
     
         13 . The active headset of  claim 9  wherein the means for sensing a condition includes an audio transducer, light sensor, a pressure sensor, or a temperature sensor.  
     
     
         14 . The active headset of  claim 9  wherein the means for sensing a condition senses movement or acceleration.  
     
     
         15 . An ANR headset having at least two operating states and comprising: 
 one or more earcups;    means for sensing a condition based on user jaw movements or blood movement within a user's head; and    means for changing the operating state of the headset from an on state to an off state in response to a perceived absence of the condition.    
     
     
         16 . The headset of  claim 15  wherein the predetermined period of time is at least one minute.  
     
     
         17 . An ANR headset having at least two operating states and comprising: 
 one or more earcups;    means for sensing a condition based on user jaw movements or blood movement, wherein the means for sensing includes a first audio transducer within one of the earcups; and    means, coupled to the means for sensing the condition, for changing the operating state of the headset from an on state to an off or standby state, wherein the means for changing the operating state includes a bandpass filter, a threshold detector, a processor, and a power switch, with the bandpass filter coupled between the threshold detector and the first audio transducer and the processor coupled between the threshold detector and the power switch.    
     
     
         18 . The headset of  claim 17 , wherein the means for changing the operating state of the headset changes the operating state from the on state to the off state in response to perceived absence of the condition for at least one minute.  
     
     
         19 . The headset of  claim 17  further including means for changing the operating state of the headset from the off state to the on state.  
     
     
         20 . The headset of  claim 17 , wherein the one earcup engages the head of a user to define a volume and the means for sensing senses changes of the volume.  
     
     
         21 . An ANR headset having at least an active operating state and an inactive or standby operating state and comprising: 
 one or more earcups;    an ANR microphone for sensing a condition based on user jaw movements or blood movement within the user's head;    a timer circuit for measuring duration of a perceived absence of the condition; and    a switch coupled to the timer circuit for switching the ANR headset from one of the active and inactive operating states to the other of the active and inactive operating states.    
     
     
         22 . The ANR headset of  claim 21 , wherein the timer circuit comprises: 
 a threshold detector; and    a microprocessor coupled to the threshold detector and to the switch.    
     
     
         23 . The ANR headset of  claim 21 , wherein the predetermined amount of time is at least one minute.  
     
     
         24 . A method of operating an ANR headset including an audio transducer attached to an earcup for engaging the ear of a user, the method comprising: 
 sensing a condition; and    switching at least a portion of the ANR headset from an active state to an inactive or standby state in response to a perceived absence of the condition for at least a predetermined amount of time.    
     
     
         25 . The method of  claim 24 , wherein switching at least the portion of the ANR headset comprises switching in response to sensing an absence of certain frequency content from the output of an audio transducer within the cavity for an amount of time of at least one minute.  
     
     
         26 . The method of  claim 24 , wherein the ANR headset includes an ANR driver within the cavity and ANR circuitry coupled to the ANR driver; and wherein the method further comprises switching the ANR circuitry from the inactive state to the active state in response to sensing deflection of a portion of the ANR driver.  
     
     
         27 . The method of  claim 24 , wherein the certain frequency content is no greater than five Hertz.  
     
     
         28 . The method of  claim 27 , wherein switching at least a portion of the ANR headset from an active state to an inactive state in response to a perceived absence of the condition comprises: 
 starting a timer in response to sensing the condition, with the timer configured to expire after measuring the predetermined amount of time; and    switching at least the portion of the ANR headset from the active state to the inactive state in response to expiration of the timer.    
     
     
         29 . An ANR headset comprising: 
 an input node for receiving an electrical signal correlated with a user wearing the headset; and    a digital processor coupled to the input node and configured to issue a turn-off command signal for at least a portion of the ANR headset after perceiving an absence of the electrical signal at the input node for at least a predetermined period of time.    
     
     
         30 . The ANR headset of  claim 29 , wherein the electrical signal has a frequency less than 5 Hertz.  
     
     
         31 . The ANR headset of  claim 29 , further comprising: 
 circuitry, coupled to the input node, for detecting and indicating detection of a condition based on user jaw movements or blood movement.    
     
     
         32 . The ANR headset of  claim 31 , wherein the circuitry for detecting and indicating detection of the condition, includes a microphone, a bandpass filter, and a threshold detector, with the bandpass filter coupled between the threshold detector and the microphone.  
     
     
         33 . The ANR headset of  claim 29 , further comprising a switch coupled to receive the turn-off signal from the processor.  
     
     
         34 . The ANR headset of  claim 33 , further comprising: 
 a plurality of battery connection terminals for coupling to one or more batteries; and    a switching regulator circuit coupled to the plurality of battery terminals, with the regulator circuit having a shutdown pin coupled to a terminal of the switch.    
     
     
         35 . An ANR headset comprising: 
 at least one audio transducer for placement adjacent an ear of a user;    circuitry for sensing a low-frequency electrical signal having a frequency no greater than five Hertz; and    circuitry responsive to a perceived absence of the low-frequency electrical signal to reduce power usage of the headset.    
     
     
         36 . The ANR headset of  claim 35 , wherein the circuitry for sensing a low-frequency electrical signal comprises: 
 a bandpass filter; and    a threshold detector coupled to the bandpass filter.    
     
     
         37 . The ANR headset of  claim 35 , wherein the circuitry responsive to a perceived absence of the low-frequency electrical signal, to reduce power usage of the headset, comprises: 
 means, responsive to the perceived absence of the low-frequency electrical signal, for reducing power usage of the headset.    
     
     
         38 . The ANR headset of  claim 35 , wherein the circuitry responsive to a perceived absence of the low-frequency electrical signal to reduce power usage of the headset, comprises: 
 circuitry for determining whether the perceived absence has lasted at least a predetermined amount of time; and    circuitry for reducing power supplied from a power supply circuit to a portion of the ANR headset in response to determining the perceived absence has lasted at least the predetermined amount of time.    
     
     
         39 . The ANR headset of  claim 38 , wherein the circuitry for reducing power supplied from the power supply circuit, comprises: 
 a processor having an output pin; and    a transistor coupled to the output pin of the processor.    
     
     
         40 . The ANR headset of  claim 38 , wherein the predetermined period of time is at least one minute.