{
  "$type": "site.standard.document",
  "description": "A compact head-up display device is provided. For that purpose, the head-up display device includes a projection optical system which includes an image forming unit to display image information and an ocular optical system to reflect light emitted from the image forming unit to display a virtual…",
  "path": "/patents/1236254",
  "publishedAt": "2019-06-13T00:00:00.000Z",
  "site": "at://did:plc:oql6ds5vnff4ugar6rruliwd/site.standard.publication/3mn3ohu7oxx5w",
  "tags": [
    "G02B27/0149",
    "MAXELL, LTD."
  ],
  "textContent": "A compact head-up display device is provided. For that purpose, the head-up display device includes a projection optical system which includes an image forming unit to display image information and an ocular optical system to reflect light emitted from the image forming unit to display a virtual image. In the ocular optical system, a free-form surface lens and a free-form surface concave mirror are arranged in order from the image forming unit. The shape of the free-form surface concave mirror is such that curvature radius RY in projection on a vertical cross section of the coordinate system of an eye-box is smaller than curvature radius RX in projection on a horizontal cross section.",
  "title": "PROJECTION OPTICAL SYSTEM, HEAD-UP DISPLAY DEVICE, AND VEHICLE"
}