Defect inspection device, defect inspection method, method for producing separator roll, and separator roll

1. A defect inspection device, comprising:

a radiation source section having an emitting surface and configured to emit an electromagnetic wave to a separator roll including (i) a core in a cylindrical shape and having a central axis and (ii) a separator for use in a battery which separator is wound around the core, the electromagnetic wave being capable of passing through the separator roll;

a sensor section having a detecting surface and configured to detect the electromagnetic wave having been emitted by the radiation source section and passed through the separator roll in order to inspect the separator roll for a defect; and

a holding mechanism configured to hold the separator roll such that the central axis of the core of the separator roll is oriented parallel to a center line connecting a center of the emitting surface of the radiation source section to the detecting surface of the sensor section in a direction perpendicular to the detecting surface.

2. The defect inspection device according to claim 1 ,

wherein

the separator roll and the detecting surface of the sensor section are not separated from each other by a structure.

3. The defect inspection device according to claim 1 ,

wherein

D 2 /D 1 is more than 1 and not more than 40, where D 1 is a distance from the emitting surface of the radiation source section to a second side surface of the separator roll which second side surface is one of opposite side surfaces of the separator roll and which second side surface faces the sensor section, and D 2 is a distance from the emitting surface of the radiation source section to the detecting surface of the sensor section.

4. The defect inspection device according to claim 1 ,

wherein

the radiation source section is configured to emit the electromagnetic wave to the separator roll from a side of a side surface of the separator roll.

5. The defect inspection device according to claim 1 ,

wherein:

the radiation source section is configured to emit the electromagnetic wave to the separator roll in such a manner that the electromagnetic wave arrives at both the separator and the core; and

the sensor section is configured to detect the electromagnetic wave so as to capture an image that includes both an image of the separator and an image of the core.

6. The defect inspection device according to claim 1 ,

wherein

the electromagnetic wave is an X ray.

7. The defect inspection device according to claim 6 ,

wherein

the center of the emitting surface of the radiation source section faces a portion of a side surface of the separator roll which portion does not correspond to the separator.

8. The defect inspection device according to claim 6 ,

wherein

the center of the emitting surface of the radiation source section faces a portion of a side surface of the separator roll which portion corresponds to a side surface of the core.

9. A defect inspection method, comprising the steps of:

causing a radiation source section having an emitting surface to emit an electromagnetic wave to a separator roll including (i) a core in a cylindrical shape and having a central axis and (ii) a separator for use in a battery which separator is wound around the core, the electromagnetic wave being capable of passing through the separator roll; and

detecting, by a sensor section having a detecting surface, the electromagnetic wave having passed through the separator roll in order to inspect the separator roll for a defect,

wherein the central axis of the core of the separator roll is oriented parallel to a center line connecting a center of the emitting surface of the radiation source section to the detecting surface of the sensor section in a direction perpendicular to the detecting surface.

10. A method for producing a separator roll, the method comprising the step of:

(a) inspecting, by the defect inspection method according to claim 9 , a separator roll for a defect, the separator roll including (i) a core in a cylindrical shape and (ii) a separator for use in a battery which separator is wound around the core, the defect being present inside the separator.

11. The method according to claim 10 , further comprising the steps of:

(b) slitting an original sheet so as to prepare the separator, the original sheet having a width larger than a width of the separator;

(c) winding the separator, prepared in the step (b), around the core so as to produce the separator roll; and

(d) packaging the separator roll, produced in the step (c),

wherein

the step (a) is carried out after the step (b) and before the step (d).

12. The method according to claim 10 ,

wherein

the step (a) is carried out in order to inspect the separator roll for a foreign object that is not less than 100 μm.