Image display device

1. An image display device comprising:

a projection port that projects image display light generated based on an image signal; and

a combiner that presents a virtual image by reflecting the image display light projected from the projection port;

wherein: with respect to a specific direction along a reflection surface of the combiner, the curvature of the combiner in the specific direction becomes smaller as a distance from the projection port becomes larger; and the reflection surface of the combiner is formed by a biconic surface,

wherein, when a visual-line direction in which the virtual image is visually recognized via the combiner is set to be a z-axis direction, a direction that is perpendicular to the z-axis direction is set to be an x-axis direction, and a direction that is perpendicular to the z-axis direction and the x-axis direction is set to be a y-axis direction,

the combiner is provided at a position where a projection position at which a projection axis of the image display light projected from the projection port intersects with the reflection surface is different from a vertex position at which both the curvature in the x-axis direction and the curvature in the y-axis direction of the biconic surface forming the reflection surface become maximum, and

wherein the combiner is shaped into a form such that a line of intersection of the biconic surface forming the reflection surface and the x-z plane is an ellipsoid line and such that a line of intersection of the biconic surface forming the reflection surface and the y-z plane is a hyperbolic curve.

2. The image display device according to claim 1 wherein the projection position on the reflection surface and the vertex position on the reflection surface are different from each other in the y-axis direction in the combiner.

3. The image display device according to claim 1 ,

wherein the reflection surface of the combiner is formed by a shape that is asymmetrical using the lower half of a biconic surface.