Vehicle surrounding viewing system

A vehicle surrounding viewing system comprising an image pick-up device including:

• a light shielding case provided on the outside of the vehicle;
• a pair of left and right transmit windows respectively disposed on right and left sides of the light shielding case;
• a prism having an isosceles triangle section shape, the prism disposed in the light shielding case so that a vertical angle of the prism is directed to a front portion of the light shielding case and left and right prism side surfaces of the prism facing to two equal sides of the isosceles triangle respectively are directed to the right and left transmit window sides respectively;
• an image pick-up element disposed at a rear portion of the prism, the image pick-up element having the image pick-up plane, the image pick-up element for receiving rays of light;
• and converting into image signals;
• a focusing lens for focusing onto the image pick-up plane the rays of light input from one surface of the left and right prism side surfaces, reflected at the other surface of the left and right prism side surfaces, and emitted from a prism rear surface of the prism;
• and
• a preventing structure arranged to cover portions of the left prism surface, the right prism surface, and the prism rear surface for preventing rays of reflected light, that pass through the right and left transmit windows and the left and right prism side surfaces in sequence respectively, then totally reflect at the prism rear surface, then pass through the left and right prism side surfaces on opposite sides, and then reflect at the right and left transmit window portions, from being focused onto the image pick-up plane.

A vehicle surrounding imaging system for picking-up simultaneously images around a vehicle in two mutually opposite directions, the system comprising:

• a prism formed as a triangular prism having an isosceles triangle sectional shape, and whose respective surfaces having first and second side surfaces that put a vertical angle of the isosceles triangle sectional shape between the first and second side surfaces, and a bottom surface opposing to the vertical angle, the prism causing the ray of light, that enters along one direction, out of rays of light that enter in two mutually opposite directions, to enter into the inside from the first side surface, then reflect toward the base surface at the second side surface, and then emit from the base surface to the outside, the prism causing the ray of light, that enters along the other direction, to enter into the inside from the second side surface, then reflect toward the base surface at the first side surface, and then emit from the base surface to the outside;
• and
• an image pick-up device for receiving the ray of light emitted from the base surface of the prism, and picking up images in above two directions;
• wherein a refractive index n of the prism, a half field angle θ of the image pick-up device, and the vertical angle δ of the prism are set to satisfy the following respective Inequalities:
• α = 90 - δ 2 - sin - 1 ⁢ ( 1 n · sin ⁢ ⁢ θ ) > sin - 1 ⁢ ( 1 n ) δ 2 - sin - 1 ⁢ { n · sin ⁢ ( δ - α ) } ≤ 0.

A prism angle setting method for a vehicle surrounding imaging system for picking-up simultaneously images around a vehicle in two mutually opposite directions, the system comprising:

• a prism formed as a triangular prism having an isosceles triangle sectional shape, and whose respective surfaces having first and second side surfaces that put a vertical angle of the isosceles triangle sectional shape between the first and second side surfaces, and a bottom surface opposing to the vertical angle, the prism causing the ray of light, that enters along one direction, out of rays of light that enter in two mutually opposite directions, to enter into the inside from the first side surface, then reflect toward the base surface at the second side surface, and then emit from the base surface to the outside, the prism causing the ray of light, that enters along the other direction, to enter into the inside from the second side surface, then reflect toward the base surface at the first side surface, and then emit from the base surface to the outside;
• and
• an image pick-up device for receiving the ray of light emitted from the base surface of the prism, and picking up images in above two directions;
• the method comprising:
• setting the vertical angle δ of the prism with respect to a refractive index n of the prism and a half field angle θ of the image pick-up device within a range to satisfy following respective Inequalities:
• α = 90 - δ 2 - sin - 1 ⁢ ( 1 n · sin ⁢ ⁢ θ ) > sin - 1 ⁢ ( 1 n ) δ 2 - sin - 1 ⁢ { n · sin ⁢ ( δ - α ) } ≤ 0.