Monitoring apparatus
First Claim
1. Apparatus for moditoring the temperature inside a refrigeration unit that experiences periodic defrost cycles of a known duration, said apparatus includinga temperature sensor located within the refrigeration unit for providing an electrical output signal indicative of the temperature level inside the unit,a comparator means for comparing the sensor output signal level with a preset signal level and providing a first output signal when the sensed temperature level is above the preset level and a second output signal when the sensed temperature level is below the preset level,a timer means connected to the output of the comparator means which is enabled when the comparator means produces said first output signal whereby the timer means generates a continuous chain of timing pulses and is disabled when the comparator means produces said second output signal,counter means being coupled to the timer means for counting the number of pulses generated by the timer means and producing a counter output signal when a preset count is reached, the duration of the counter means cycle being greater than the duration of the defrost cycle, andan audio means coupled to the output of both the timer means and the counter means and including an audio transducer means providing a first audible alert signal any time the timer means is enabled and a second audible alarm signal when the counter means reaches the preset count,said audio means including time constant circuit means for actuating said audio transducer means for leading edge portions of said pulses to produce audible ticks as said first audible alert signal, and gating means enabled by said counter output signal for actuating said audio transducer means to produce an audible tone as said second audible alarm signal.
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Accused Products
Abstract
Monitoring apparatus for sensing the temperature within a refrigeration unit that experiences periodic defrosting cycles. The apparatus is capable of discerning the differences between a normal defrost cycle and system failure and provides a warning signal when a failure occurs.
16 Citations
19 Claims
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1. Apparatus for moditoring the temperature inside a refrigeration unit that experiences periodic defrost cycles of a known duration, said apparatus including
a temperature sensor located within the refrigeration unit for providing an electrical output signal indicative of the temperature level inside the unit, a comparator means for comparing the sensor output signal level with a preset signal level and providing a first output signal when the sensed temperature level is above the preset level and a second output signal when the sensed temperature level is below the preset level, a timer means connected to the output of the comparator means which is enabled when the comparator means produces said first output signal whereby the timer means generates a continuous chain of timing pulses and is disabled when the comparator means produces said second output signal, counter means being coupled to the timer means for counting the number of pulses generated by the timer means and producing a counter output signal when a preset count is reached, the duration of the counter means cycle being greater than the duration of the defrost cycle, and an audio means coupled to the output of both the timer means and the counter means and including an audio transducer means providing a first audible alert signal any time the timer means is enabled and a second audible alarm signal when the counter means reaches the preset count, said audio means including time constant circuit means for actuating said audio transducer means for leading edge portions of said pulses to produce audible ticks as said first audible alert signal, and gating means enabled by said counter output signal for actuating said audio transducer means to produce an audible tone as said second audible alarm signal.
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8. Apparatus for monitoring a variable parameter inside an enclosed unit that experiences periodic cycles of a known duration during which time the variable parameter will change, said apparatus including
a sensor located within the enclosed unit for providing an electrical output signal indicative of the parameter level inside the unit, a comparator means for comparing the sensor output signal level with a preset signal level and providing a first output signal when the sensed parameter level is above the preset level and a second output signal when the sensed parameter level is below the preset level, a timer means connected to the output of the comparator means which is enabled when the comparator means produces said first output signal whereby the timer means generates a continuous chain of timing pulses and is disabled when the comparator produces said second output signal, counter means being coupled to the timer means for counting the number of pulses generated by the timer means and producing a counter output signal when a preset count is reached, the duration of the counter means cycle being greater than the duration of the periodic cycle, and an audio means coupled to the output of both the timer means and the counter means and including an audio transducer means providing a first audible alert signal any time the timer means is enabled and second audible alarm signal when the counter means reaches the preset count, said audio means including time constant circuit means for actuating said audio transducer means for leading edge portions of said pulses to produce audible ticks as said first audible alert signal, and logic means enabled by said counter output signal for actuating said audio transducer means to produce an audible tone as said second audible alarm signal.
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13. Apparatus for monitoring the temperature inside a refrigeration unit that experiences periodic defrost cycles of a known duration, said apparatus including
a temperature sensor located within the refrigeration unit for providing an electrical output signal indicative of the temperature level inside the unit, a comparator means for comparing the sensor output signal level with a preset signal level and providing a first output signal when the sensed temperature level is above the preset level and a second output signal when the sensed temperature level is below the preset level, a timer means connected to the output of the comparator means which is enabled when the comparator means produces said first output signal whereby the timer means generates a continuous chain of timing pulses and is disabled when the comparator means produces said second output signal, counter means being coupled to the timer means for counting the number of pulses generated by the timer means and producing a counter output signal when a preset count is reached, the duration of the counter means cycle being greater than the duration of the defrost cycle, an audio means coupled to the output of both the timer means and the counter means and including an audio transducer means providing a first audible alert signal any time the timer means is enabled and a second audible alarm signal when the counter means reaches the preset count, and reset means including automatic reset circuit means for automatically resetting the counter means to zero and disabling the timer means when the sensed temperature level falls to or below said preset level before said preset count is reached thus terminating said first audible alert signal, and manual reset circuit means having a manual reset switch and holding circuit means for holding said audio means on to produce said second audible alarm signal once said preset has been reached, notwithstanding a return of said sensed temperature level to or below said preset level, until said manual reset switch has been actuated.
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17. Apparatus for monitoring a variable parameter inside an enclosed unit that experiences periodic cycles of a known duration during which time the variable parameter will change, said apparatus including
a sensor located within the enclosed unit for providing an electrical output signal indicative of the parameter level inside the unit, a comparator means for comparing the sensor output signal level with a preset signal level and providing a first output signal when the sensed parameter level is above the preset level and a second output signal when the sensed parameter level is below the preset level, a timer means connected to the output of the comparator means which is enabled when the comparator means produces said first output signal whereby the timer means generates a continuous chain of timing pulses and is disabled when the comparator means produces said second output signal, counter means being coupled to the timer means for counting the number of pulses generated by the timer means and producing a counter output signal when a preset count if reached, the duration of the counter means cycle being less than the duration of the periodic cycle, an audio means coupled to the output of both the timer means and the counter means and including an audio transducer means providing a first audible alert signal when the timer means is enabled and second audible alarm signal when the counter means reaches the preset count, and reset means including automatic reset curcuit means for automatically resetting the counter means to zero and disabling the timer means in response to occurrence of the second output signal of said comparator means before said counter attains said preset count thus terminating said first audible alert signal, and manual reset circuit means having a manual reset switch and holding circuit means for holding said audio means on to produce said second audible alarm signal once said preset count has been attained, notwithstanding a return of said comparator means from said second output signal to said first output signal, until said manual reset switch has been actuated.
Specification