SAFETY APPARATUS AND FAULT DETECTION METHODS
First Claim
1. A safety apparatus comprising:
- an input signal determination unit for determining whether input signals from a plurality of sensors each detecting a safety state of equipment are all in an ON state, all in an OFF state, or in an inconsistent state between the sensors;
a first latch storage unit for retaining an inconsistent state record if the input signal determination unit determines that the input signals from the plurality of sensors are in an inconsistent state, and freeing the inconsistent state record if the input signal determination unit determines that the input signals from the plurality of sensors are all in an OFF state;
a sensor fault determination unit for performing a sensor fault determination at first timing when the input signal determination unit determines that the input signals from the plurality of sensors are all in an ON state, the sensor fault determination including determining that at least one of the plurality of sensors is failed if the first latch storage unit retains the inconsistent state record and determining that none of the plurality of the sensors is failed if the first latch storage unit does not retain the inconsistent state record; and
an operation enable/disable unit for enabling/disabling an operation of the equipment based on the input signals from the plurality of sensors and a determination result of the sensor fault determination by the sensor fault determination unit.
1 Assignment
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Accused Products
Abstract
A safety apparatus includes: a latch circuit which retains an inconsistent state record when input signals from a plurality of sensors are in an inconsistent state, and frees the inconsistent state record when the input signals from the plurality of sensors are all in an OFF state; and an AND circuit which performs a sensor fault determination at timing when the input signals from the plurality of sensors are all in an ON state, the sensor fault determination including determining that at least one of the plurality of sensors is failed if the latch circuit retains the inconsistent state record and determining that none of the plurality of the sensors is failed if the latch circuit retains no inconsistent state record.
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Citations
10 Claims
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1. A safety apparatus comprising:
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an input signal determination unit for determining whether input signals from a plurality of sensors each detecting a safety state of equipment are all in an ON state, all in an OFF state, or in an inconsistent state between the sensors; a first latch storage unit for retaining an inconsistent state record if the input signal determination unit determines that the input signals from the plurality of sensors are in an inconsistent state, and freeing the inconsistent state record if the input signal determination unit determines that the input signals from the plurality of sensors are all in an OFF state; a sensor fault determination unit for performing a sensor fault determination at first timing when the input signal determination unit determines that the input signals from the plurality of sensors are all in an ON state, the sensor fault determination including determining that at least one of the plurality of sensors is failed if the first latch storage unit retains the inconsistent state record and determining that none of the plurality of the sensors is failed if the first latch storage unit does not retain the inconsistent state record; and an operation enable/disable unit for enabling/disabling an operation of the equipment based on the input signals from the plurality of sensors and a determination result of the sensor fault determination by the sensor fault determination unit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A fault detection method by which a safety apparatus that enables/disables an operation of equipment based on input signals from a plurality of sensors each detecting a safety state of the equipment detects a fault of the plurality of sensors, the fault detection method comprising:
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a first step of acquiring the input signals from the plurality of sensors; a second step of determining whether the acquired input signals are all in an ON state, all in an OFF state, or in an inconsistent state between the sensors; a third step of storing a first state into a first storage unit if a determination result of the second step indicates an inconsistent state, the first storage unit being configured to store either one of the first state and a second state; a fourth step of storing the second state into the first storage unit if the determination result of the second step indicates all being in an OFF state; and a fifth step of determining that at least one of the plurality of sensors is failed when the first storage unit contains the first state and determining that none of the plurality of sensor is failed when the first storage unit contains the second state if the determination result of the second step indicates all being in an ON state.
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10. A fault detection method by which a safety apparatus that enables/disables an operation of equipment based on input signals from a plurality of sensors each detecting a safety state of the equipment detects a fault of the plurality of sensors, the fault detection method comprising:
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a first step of acquiring the input signals from the plurality of sensors; a second step of determining whether the acquired input signals are all in an ON state, all in an OFF state, or in an inconsistent state between the sensors; a third step of storing a first state into a first storage unit and storing a third state into a second storage unit if a determination result of the second step indicates all being in an OFF state, the first storage unit being configured to store either one of the first state and a second state, the second storage unit being configured to store either one of the third state and a fourth state; a fourth step of storing the second state into the first storage unit when the second storage unit contains the fourth state if the determination result of the second step indicates an inconsistent state; and a fifth step of storing the fourth state into the second storage unit when the first storage unit contains the first state and determining that at least one of the plurality of sensor is failed when the first storage unit contains the second state if the determination result of the second step indicates all being in an ON state.
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Specification