Protection device, protection method using the same, method for processing signal using the same, and method for detecting quantity of electricity using the same

1. A protection device for detecting a temperature, a voltage, or a current in a predetermined monitoring place in an electronic apparatus supplied with electric power from an external power source to protect the electronic apparatus from an excessive temperature, an overvoltage, or an overcurrent, the protection device comprising:

a detection element arranged in the monitoring place for detecting the temperature, the voltage, or the current of the electronic apparatus to output an electric signal;

an oscillating circuit for generating a clock signal having a predetermined cycle and a predetermined ON time; and

a detection circuit for detecting the electric signal generated in the detection element, the detection circuit including a first switching circuit and the detection element, where the first switching circuit is connected to the detection element and switches the detection element between an active state and an inactive state,

wherein during the ON time of the clock signal, the first switching circuit is in an ON state to switch the detection element to the active state, whereas during an OFF time of the clock signal, the first switching circuit is in an OFF state to switch the detection element to the inactive state, and

supply of the electric power to the electronic apparatus is shut off according to an output signal output from the detection circuit.

2. The protection device of claim 1 , further comprising a second switching circuit for controlling the supply of the electric power to the electronic apparatus, the second switching circuit being provided for an electric power supply line between the external power source and the electronic apparatus, wherein

the detection element is a temperature detection element for detecting a temperature of the second switching circuit to output the electric signal according to the detected temperature, and

the second switching circuit is turned off according to the output signal of the detection circuit.

3. The protection device of claim 1 , further comprising a second switching circuit for controlling the supply of the electric power to the electronic apparatus, the second switching circuit being provided for an electric power supply line between the external power source and the electronic apparatus, wherein

the detection element is a temperature detection element for detecting a temperature of an element constituting the electronic apparatus to output the electric signal according to the detected temperature, and

the second switching circuit is turned off according to the output signal of the detection circuit.

4. The protection device of claim 1 , further comprising a second switching circuit for controlling the supply of the electric power to the electronic apparatus, the second switching circuit being provided for an electric power supply line between the external power source and the electronic apparatus, wherein

the detection element is a voltage detection element which is connected to the electric power supply line for detecting a voltage of the electric power supply line to output the electric signal according to the detected voltage, and

the second switching circuit is turned off according to the output signal of the detection circuit.

5. The protection device of claim 1 , further comprising a second switching circuit for controlling the supply of the electric power to the electronic apparatus, the second switching circuit being provided for an electric power supply line between the external power source and the electronic apparatus, wherein

the detection element is a current detection element which is connected to the electric power supply line for detecting a current responsive to an output current of the external power source to output the electric signal according to the detected current, and

the second switching circuit is turned off according to the output signal of the detection circuit.

6. The protection device of claim 1 , further comprising a protection control circuit for generating an input signal during the ON time of the clock signal, the input signal being input to the detection element, wherein

the detection element includes a plurality of detection elements arranged in N (N is an integer greater than or equal to 2) detection places, and

the protection control circuit drives the detection elements according to N different phases synchronous with the clock signal.

7. The protection device of claim 6 , wherein the protection control circuit includes a divider circuit for dividing the clock signal by at least N.

8. The protection device of claim 1 , further comprising a judging circuit which includes a comparison circuit for comparing the output signal of the detection circuit with a reference signal serving as a reference and outputting a result of the comparison, wherein

the judging circuit counts an output signal of the comparison circuit, and when a result of the count exceeds a predetermined number of times, the judging circuit shuts off the supply of the electric power to the electronic apparatus.

9. The protection device of claim 8 , wherein the judging circuit further includes:

a delay circuit for outputting a signal obtained by delaying the clock signal for a predetermined time;

the detection circuit for intermittently supplying a current to the detection element according to the clock signal to output the signal generated in the detection element;

a logical circuit for performing logical AND operation of the output signal of the comparison circuit and the signal output from the delay circuit; and

a counter circuit whose reset terminal receives an output signal of the logical circuit and whose clock input terminal receives the output signal of the comparison circuit for count operation, wherein

the supply of the electric power to the electronic apparatus is shut off according to an output signal of the counter circuit.

10. The protection device of claim 1 , further comprising recording means for recording a temperature, a voltage, or a current at which the supply of the electric power to the electronic apparatus is shut off.

11. The protection device of claim 10 , wherein the recording means records a bigger one of data detected by the detection circuit and data in the recording means.

12. The protection device of claim 10 , further comprising a central processing unit, wherein the recording means operates according to a signal given from the central processing unit.

13. The protection device of claim 12 , further comprising transmission means for externally transmitting an internal signal held in the central processing unit.

14. The protection device of claim 12 , wherein

the central processing unit is connected to a first power source which is detachably provided, and

the recording means is connected to a second power source which is provided independently of the first power source.

15. A protection method using a protection device for detecting a temperature, a voltage, or a current in a predetermined monitoring place in an electronic apparatus to protect the electronic apparatus from an excessive temperature, an overvoltage, or an overcurrent,

the protection device including: a detection element arranged in the monitoring place for detecting a value of the temperature, the voltage, or the current in the monitoring place; a clock generation circuit for generating a clock signal which is output from the clock generation circuit, the clock signal having a predetermined cycle and a predetermined ON time; and a current source for outputting a signal current during the ON time of the clock signal,

the protection method comprising the steps of:

switching the detection element to an active state during the ON time of the clock signal, and collecting a quantity of electricity generated by applying the signal current to the detection element;

switching the detection element to an inactive state during the OFF time of the clock signal; and

protecting the electronic apparatus according to the collected quantity of the electricity.

16. A method for processing a signal using a protection device for detecting a temperature, a voltage, or a current in a predetermined monitoring place in an electronic apparatus to protect the electronic apparatus from an excessive temperature, an overvoltage, or an overcurrent, the method comprising the steps of:

generating a clock signal having a predetermined cycle and a predetermined ON time;

detecting the temperature, the voltage, or the current in the monitoring place during the ON time of the clock signal, but not detecting the temperature, the voltage, or the current in the monitoring place during an OFF time of the clock signal;

shutting off supply of electric power to the electronic apparatus according to an output signal of a detection circuit; and

recording output data from temperature detection means, voltage detection means, or current detection means at a time when the supply of the electric power is shut off according to the output signal of the detection circuit,

wherein a detection element utilized to detect the temperature is switched off during the OFF time of the clock signal.

17. The method of claim 16 , further comprising the step of transferring the output data to a central processing unit provided outside.

18. A method for detecting a quantity of electricity using a protection device for detecting a temperature, a voltage, or a current in a predetermined monitoring place in an electronic apparatus to protect the electronic apparatus from an excessive temperature, an overvoltage, or an overcurrent,

the protection device including: a detection element arranged in the monitoring place for detecting a value of the temperature, the voltage, or the current in the monitoring place; a clock generation circuit for generating a clock signal which is output from the clock generation circuit, the clock signal having a predetermined cycle and a predetermined ON time; and a current source for outputting a signal current during the ON time of the clock signal,

the method comprising the steps of:

(a) switching the detection element to an active state during the ON time of the clock signal, and applying the signal current to the detection element;

(b) during the OFF time of the clock signal, the signal current applied to the detection element is shut off to switch the detection element to an inactive state; and

(c) detecting the quantity of the electricity generated from the detection element due to the application of the signal current.

19. The method of claim 18 , wherein

the monitoring place includes a plurality of monitoring places provided in the electronic apparatus,

the detection element includes a plurality of detection elements respectively arranged in the plurality of monitoring places,

step (a) includes sequentially applying the signal current from the current source to the plurality of the detection elements; and

step (b) includes sequentially detecting the quantity of the electricity generated from each of the detection elements due to the sequential application of the signal current.