Detection device having contacting variable resistor portion with contact area varying correspondingly to load for improved linearity of output voltage

1. A detection device comprising:

a first electrode;

a second electrode;

a variable resistor portion formed between first electrode and the second electrode; and

a contact member that is elastically deformable and has a contact area with the variable resistor portion,

wherein the contact area increases according to a load that is applied to the contact member in a direction toward the variable resistor portion,

wherein the variable resistor portion includes an output varying region that varies an output voltage from the second electrode according to the contact area, and

wherein the output varying region is formed so that a contact distance between the variable resistor portion and an outer peripheral portion of the contact member becomes longer as the contact area becomes larger.

2. The detection device as claimed in claim 1 , wherein the output varying region includes a first portion having a width that becomes narrower in a direction separated more from the first electrode.

3. The detection device as claimed in claim 2 , wherein a shape of the contact area varies correspondingly according to the load.

4. The detection device as claimed in claim 2 , wherein the contact member has a truncated cone shape.

5. The detection device as claimed in claim 2 , wherein the output varying region includes a second portion having a width that becomes narrower in a direction separated more from the second electrode.

6. The detection device as claimed in claim 5 , wherein

the variable resistor portion includes a contact portion connecting the first portion and the second portion, and

the contact member is arranged to make contact with the contact portion.

7. The detection device as claimed in claim 6 , wherein the first portion and the second portion are arranged to oppose each other via the contact portion.

8. The detection device as claimed in claim 6 , wherein the contact portion includes a low-resistance portion having a resistivity lower than resistivities of the first portion and the second portion.

9. The detection device as claimed in claim 8 , wherein the low-resistance portion is formed by a silver pattern.

10. The detection device as claimed in claim 5 , wherein the contact member has a resistivity lower than resistivities of the first portion and the second portion.

11. The detection device as claimed in claim 5 , wherein the first portion and the second portion have the same shape.

12. The detection device as claimed in claim 5 , wherein at least one of the first portion and the second portion has a shape selected from a group consisting of a fan shape, a trapezoidal shape, and a bell shape.

13. The detection device as claimed in claim 5 , wherein a shape of the contact area varies correspondingly according to the load.

14. The detection device as claimed in claim 5 , wherein the contact member has a truncated cone shape.

15. The detection device as claimed in claim 1 , further comprising:

a third electrode; and

a fixed resistor portion formed between the second electrode and the third electrode.

16. The detection device as claimed in claim 15 , wherein the variable resistor portion and the fixed resistor portion have the same resistivity.

17. The detection device as claimed in claim 1 , wherein a shape of the contact area varies correspondingly according to the load.

18. The detection device as claimed in claim 1 , wherein the contact member has a truncated cone shape.