Thermal protection apparatus for a secure electronic appliance, in particular a postage meter
First Claim
1. Apparatus for detecting that a predetermined temperature threshold has been crossed by circuits of a secure electronic appliance, in particular said circuits being of a postage meter or "franking machine", and for preventing any subsequent use of said appliance after said threshold has been crossed, said apparatus comprising the following elements disposed inside a protected enclosure:
- a reversible thermostatic switch (16;
35) changing from a first stable state to a second stable state when said predetermined threshold is crossed, and delivering an alarm signal when said switch is in said second stable state; and
control means co-operating with said switch to respond to said alarm signal by delivering a disable signal for preventing any use of said electronic appliance;
said apparatus further comprising;
a voltage source (15) delivering a DC voltage;
an electrical or electronic component (17;
21) connected in a loop with said voltage source and said switch, said component taking a first state corresponding to said first stable state and a second state corresponding to said second stable state so that a current passing through said switch causes said electrical or electronic component to go non-reversibly from said first state to said second state.
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Accused Products
Abstract
The apparatus detects the fact that a predetermined temperature threshold, in particular a low temperature threshold, has been crossed, and prevents any subsequent use of the appliance. The apparatus includes a reversible thermostatic switch capable of changing from a first stable state to a second stable state, and of delivering an alarm signal when it finds itself in the second state; and control means co-operating with the switch to respond to the alarm signal by delivering a disable signal for disabling the electronic appliance. According to the invention, the apparatus further includes a DC voltage source (15), an electrical or electronic component (17) capable of taking two states corresponding to said first and second stable states connected in a loop with the voltage source and the switch so that a current passing through the thermostatic switch causes a change from the first state to the second state.
164 Citations
15 Claims
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1. Apparatus for detecting that a predetermined temperature threshold has been crossed by circuits of a secure electronic appliance, in particular said circuits being of a postage meter or "franking machine", and for preventing any subsequent use of said appliance after said threshold has been crossed, said apparatus comprising the following elements disposed inside a protected enclosure:
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a reversible thermostatic switch (16;
35) changing from a first stable state to a second stable state when said predetermined threshold is crossed, and delivering an alarm signal when said switch is in said second stable state; andcontrol means co-operating with said switch to respond to said alarm signal by delivering a disable signal for preventing any use of said electronic appliance; said apparatus further comprising; a voltage source (15) delivering a DC voltage; an electrical or electronic component (17;
21) connected in a loop with said voltage source and said switch, said component taking a first state corresponding to said first stable state and a second state corresponding to said second stable state so that a current passing through said switch causes said electrical or electronic component to go non-reversibly from said first state to said second state. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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Specification