Measuring device, measuring system, and measuring method

1 . A measuring device which measures a state of a plurality of weld zones formed when a weldment is welded to a workpiece at a plurality of locations, the measuring device comprising:

a plurality of application circuits configured to apply a current to each of one or more weld zones exclusively selected among the plurality of weld zones;

a detection circuit configured to detect a voltage obtained by combining voltages indicating magnitudes of voltage drops generated respectively by the plurality of weld zones due to the application of the current; and

a processor configured to output information indicating the state of the plurality of weld zones on the basis of the voltages combined.

2 . The measuring device according to claim 1 , comprising:

a plurality of pairs of contacts connected to both ends of each of the application circuits; and

another pair of contacts connected to both ends of the detection circuit, wherein

each contact of the plurality of pairs of contacts comes into contact with a corresponding one of a plurality of first areas of the weldment or the workpiece in the vicinity of a weld zone of the plurality of weld zones, and

each contact of the other pair of contacts comes into contact with a corresponding one of a plurality of second areas of the weldment or the workpiece farther from the plurality of weld zones than the plurality of first areas with which the plurality of pairs of contacts come into contact.

3 . The measuring device according to claim 2 , wherein

the other pair of contacts come into contact with the plurality of second areas of the weldment or the workpiece positioned on or in the vicinity of any one line passing through a center of gravity of a polygon formed by the plurality of weld zones and midpoints of respective sides of the polygon.

4 . The measuring device according to claim 2 , wherein

the other pair of contacts come into contact with the plurality of second areas of the weldment and the workpiece positioned at substantially equal distances from each of the plurality of weld zones.

5 . The measuring device according to claim 2 , wherein

each one pair of the plurality of pairs of contacts come into contact with the plurality of first areas positioned in the vicinity of any one weld zone exclusively selected from first N weld zones among 2N weld zones (where N is a natural number of 2 or greater) among the plurality of weld zones, and

each other pair of the plurality of pairs of contacts come into contact with the plurality of first areas positioned in the vicinity of any one weld zone exclusively selected from remaining N weld zones among the 2N weld zones.

6 . The measuring device according to claim 1 , further comprising:

a holding circuit configured to hold a threshold value for determining the state, wherein

when the voltage detected by the detection circuit exceeds the threshold value, the processor generates, as the information, state information indicating that the state of the plurality of weld zones is good.

7 . The measuring device according to claim 1 , wherein

each of the plurality of application circuits applies the current in the same direction to the one or more weld zones, the weld zones being different from each other.

8 . A measuring method for measuring a state of a plurality of weld zones formed when a weldment is welded to a workpiece at a plurality of locations, the measuring method comprising:

applying a current to one or more weld zones exclusively selected among the plurality of weld zones;

detecting a voltage obtained by combining voltages indicating magnitudes of voltage drops generated by each of the one or more weld zones due to the application of the current; and

outputting information indicating the state of the plurality of weld zones on the basis of the voltages combined.

9 . A measuring system which measures a state of a plurality of weld zones formed when a weldment is welded to a workpiece at a plurality of locations, the measuring system comprising:

one or more current application devices configured to apply a current to each of one or more weld zones exclusively selected among the plurality of weld zones;

a voltage detection device configured to detect a voltage obtained by combining voltages indicating magnitudes of voltage drops generated respectively by the plurality of weld zones due to the application of the current; and

an information processing device configured to output information indicating the state of the plurality of weld zones on the basis of the voltages combined.