Contact probe and signal transmission method
A contact probe includes a first plunger, a second plunger, a coil spring, and a pipe; the first plunger includes a first slide portion that slides along the inner periphery of the pipe; the second plunger includes a second slide portion that slides along the inner periphery of the pipe; and the coil spring includes: a first attachment portion that is attached to the first plunger and tightly wound; a second attachment portion that is attached to the second plunger and tightly wound; a coarsely wound portion; a first contact portion including one end connected to the first attachment portion and another end connected to the coarsely wound portion and contacting the pipe; and a second contact portion including one end connected to the coarsely wound portion and another end connected to the second attachment portion and contacting to the pipe.
1. A contact probe for contacting with electrodes at both ends of a longitudinal length of the contact probe and transmitting a signal, the contact probe comprising:
a first plunger configured to contact a first electrode at one end of the longitudinal length;
a second plunger configured to contact a second electrode different from the first electrode at another end of the longitudinal length;
a coil spring connected to the first plunger at one end of the coil spring and connected to the second plunger at another end of the coil spring; and
a pipe provided inside the coil spring, wherein
the first plunger includes a first slide portion provided at another end of the first plunger opposite to the one end of the first plunger contacting the first electrode, the first slide portion being configured to slide along an inner periphery of the pipe,
the second plunger includes a second slide portion provided at another end of the second plunger opposite to the one end of the second plunger contacting the second electrode, the second slide portion being configured to slide along the inner periphery of the pipe, and
the coil spring includes:
a first attachment portion that is tightly wound, the first attachment portion being provided at the one end of the coil spring and attached to the first plunger;
a second attachment portion that is tightly wound, the second attachment portion being provided at the other end of the coil spring and attached to the second plunger;
a coarsely wound portion wound at preset pitches;
a first contact portion including one end connected to the first attachment portion and another end connected to the coarsely wound portion, the first contact portion contacting the pipe, the first contact portion being tightly wound in a natural state; and
a second contact portion including one end connected to the coarsely wound portion and another end connected to the second attachment portion, the second contact portion contacting the pipe, the second contact portion being tightly wound in the natural state.
2. The contact probe according to claim 1 , wherein in a natural state where no load other than gravity is being applied to the contact probe, the first slide portion and the second slide portion are positioned inside the pipe regardless of a position of the pipe along an axial direction of the contact probe.
3. A signal transmission method for transmitting a signal, via the contact probe according to claim 1 , from the second electrode to the first electrode, the signal transmission method comprising
transmitting the signal input from the second electrode to the second plunger to the first electrode via at least one of:
a first path through which the signal reaches the first electrode via the second attachment portion, the second contact portion, the pipe, the first contact portion, and the first attachment portion; and
a second path through which the signal reaches the first electrode via the second slide portion, the pipe, and the first slide portion.
4. The contact probe according to claim 1 , wherein
a part of the coarsely wound portion connected to the first contact portion or to the second contact portion becomes tightly wound as a load applies to the contact probe, and
the part of the coarsely portion functions as the first contact portion or the second contact portion.