Electrostatic protection element

1. An electrostatic protection element comprising:

a substrate of a first conductivity type;

a first low-concentration diffusion region of a second conductivity type and a second low-concentration diffusion region of the first conductivity type which are formed on said substrate, the second conductivity type being different from the first conductivity type; a first high-concentration diffusion region of the second conductivity type and a second high-concentration diffusion region of the first conductivity type which are (i) formed in said first low-concentration diffusion region, and (ii) electrically connected with each other;

a third high-concentration diffusion region of the first conductivity type and a fourth high-concentration diffusion region of the second conductivity type which are (i) formed in said second low-concentration diffusion region, and (ii) electrically connected with each other;

a fifth high-concentration diffusion region of the first conductivity type formed in said first low-concentration diffusion region;

a sixth high-concentration diffusion region of the second conductivity type formed in said second low-concentration diffusion region; and a seventh high-concentration diffusion region which (i) is formed in one of said first low-concentration diffusion region and said second low-concentration diffusion region, and (ii) has a conductivity type different from the conductivity type of one of said first low-concentration diffusion region and said second low-concentration diffusion region in which said seventh high-concentration diffusion region is formed,

wherein said seventh high-concentration diffusion region is electrically connected with one of said second high-concentration diffusion region and said fourth high-concentration diffusion region whichever having the conductivity type different from the conductivity type of said seventh high-concentration diffusion region.

2. The electrostatic protection element according to claim 1 ,

wherein the first conductivity type is a p-type, and the second conductivity type is an n-type,

said first high-concentration diffusion region and said second high-concentration diffusion region are connected to a high potential, and

said third high-concentration diffusion region and said fourth high-concentration diffusion region are connected to a low potential.

3. The electrostatic protection element according to claim 1 ,

wherein the first conductivity type is an n-type, and the second conductivity type is a p-type,

said first high-concentration diffusion region and said second high-concentration diffusion region are connected to a low potential, and

said third high-concentration diffusion region and said fourth high-concentration diffusion region are connected to a high potential.

4. The electrostatic protection element according to claim 1 ,

wherein said fifth high-concentration diffusion region and said sixth high-concentration diffusion region are electrically connected with each other.

5. The electrostatic protection element according to claim 4 , further comprising

an external terminal which is electrically connected to a connection point between said fifth high-concentration diffusion region and said sixth high-concentration diffusion region.

6. The electrostatic protection element according to claim 4 ,

wherein said fifth high-concentration diffusion region and said sixth high-concentration diffusion region are electrically connected with each other via a resistive element.

7. A display apparatus comprising:

a control circuit which controls a signal line and a scanning line based on one or more signals provided from outside;

a signal line driving circuit;

a scanning line driving circuit; and

said one or more electrostatic protection elements according to claim 4 .

8. The display apparatus according to claim 7 ,

wherein said one or more electrostatic protection elements are implemented in one or more of said control circuit, said signal line driving unit, and said scanning line driving circuit.

9. The electrostatic protection element according to claim 1 , further comprising:

an external terminal which is electrically connected to said fifth high-concentration diffusion region; and

an external terminal which is electrically connected to said sixth high-concentration diffusion region.

10. A display apparatus comprising:

a control circuit which controls a signal line and a scanning line based on one or more signals provided from outside;

a signal line driving circuit;

a scanning line driving circuit; and

said one or more electrostatic protection elements according to claim 9 ,

wherein said one or more electrostatic protection elements are implemented in one or more of said control circuit, said signal line driving unit, and said scanning unit, and

said two external terminals of said electrostatic protection element are connected with each other via one or more resistive elements provided to said display apparatus.