Near-infrared sensor cover

1. A near-infrared sensor cover configured to cover a transmitting unit and a receiving unit for near-infrared rays in a near-infrared sensor, the near-infrared sensor cover comprising:

a cover body having transmissiveness to near-infrared rays, wherein

the cover body includes:

a base made of a plastic, and

a heater unit that is arranged rearward of the base in a transmission direction of the near-infrared rays and includes a wire-like heating element, the heating element configured to generate heat when energized,

the base includes a rear portion that includes a rear surface of the base in the transmission direction,

in the rear portion of the base, at least part of a section that is different from a section in which the heater unit is provided is formed by a reflection suppression structure including asperities, and

the asperities include a reflection suppression surface that is inclined relative to the transmission direction and reduces reflection of the near-infrared rays.

2. The near-infrared sensor cover according to claim 1 , wherein

the reflection suppression structure includes protrusions,

the protrusions each include the reflection suppression surface and are adjacent to and parallel with each other, and

each protrusion has a triangular cross section.

3. The near-infrared sensor cover according to claim 2 , wherein

a height of each protrusion from a base to a vertex is constant in a direction in which the protrusion extends,

the height of each protrusion is set to be in a range from 150 nm to 400 nm, and

a measurement of the base of each protrusion in an arrangement direction of the protrusions is set to be in a range from 170 nm to 200 nm.

4. The near-infrared sensor cover according to claim 2 , wherein

each protrusion includes concavities that are connected together in a direction in which the protrusion extends,

each concavity is arcuately recessed from a vertex toward a base of the protrusion, and a depth of the concavity varies in the direction in which the protrusion extends,

a height of each protrusion from the base to a highest position in the vertex is set to be in a range from 150 nm to 400 nm,

a measurement of the base of each protrusion in an arrangement direction of the protrusions is set to be in a range from 150 nm to 400 nm,

a radius of each concavity is set to be in a range from 1 mm to 10 mm,

a pick feed, which is a measurement of each concavity in a direction in which the protrusions extend, is set to be in a range from 30 μm to 90 μm, and

a scallop, which is a depth of each concavity, is set to be in a range from 0.01 μm to 0.1 μm.

5. The near-infrared sensor cover according to claim 1 , wherein

the reflection suppression structure includes projections each having a shape of a polygonal pyramid and the reflection suppression surface, and

the projections are arranged in two intersecting directions, while being adjacent to each other.

6. The near-infrared sensor cover according to claim 5 , wherein

each projection has a shape of a quadrangular pyramid and includes first and second base edges that are adjacent to each other,

a length of the first base edge is set to be in a range from 170 nm to 200 nm,

a length of the second base edge is set to be in a range from 170 nm to 200 nm,

the projections are arranged such that the first base edges are arranged linearly and the second base edges are arranged linearly, and

a height of each projection is set to be in a range from 150 nm to 400 nm.

7. The near-infrared sensor cover according to claim 1 , comprising:

a hydrophilization film that is provided rearward in the transmission direction of the reflection suppression structure,

wherein the reflection suppression structure is covered with the hydrophilization film.