TECHNICAL FIELD

The present invention relates to a head-up display apparatus.

BACKGROUND ART

The driver of a vehicle performs driving while carefully viewing the front through a windshield, and visually observing meters on an instrument panel. That is, the line of sight of the driver moves toward the front and the meters below. When the driver can view the meters while viewing the front, the movement of the line of sight does not occur, and hence an improvement in drivability (finally safety) can be expected. In view of the finding, a head-up display apparatus has started to be developed and put into practical use. In the head-up display apparatus, a cover member configured to cover the opening portion of an optical path is arranged for preventing the entry of foreign matter, such as dust, into a housing in which an optical system is stored. Further, a polarizing plate may be bonded to the cover member for preventing an increase in temperature in the housing (specifically for preventing the incidence of sunlight) (e.g., Patent Literature 1). However, such head-up display apparatus involves a problem in that when the driver wears a pair of polarized sunglasses, its viewability remarkably reduces (in the worst case, a blackout occurs). In addition, a related-art head-up display apparatus involves a problem in that its heat resistance is insufficient.

CITATION LIST

Patent Literature

[PTL 1] JP 2008-70504 A

SUMMARY OF INVENTION

Technical Problem

The present invention has been made to solve the conventional problems, and an object of the present invention is to provide a head-up display apparatus that is excellent in viewability when a display screen is viewed through a pair of polarized sunglasses, and that is excellent in heat resistance.

Solution to Problem

According to one embodiment of the present invention, there is provided a head-up display apparatus, including: a display unit configured to output projection light; at least one reflector configured to reflect the projection light; a housing, which has an opening portion, and is configured to store the display unit and the reflector therein; a cover member configured to cover the opening portion; and a polarizing plate with a retardation layer, which is arranged on a housing inner side of the cover member, and includes a retardation layer and a polarizer in the stated order from a cover member side. The retardation layer has an in-plane retardation Re(550) of from 100 nm to 200 nm, or from 220 nm to 320 nm. The head-up display apparatus according to the one embodiment of the present invention is configured so that an angle of reflection of the projection light output from the housing through the opening portion with respect to a windshield is 30° or less, or is 40° or more.

In one embodiment, the polarizer contains an aromatic disazo compound represented by the formula (1) to be described later.

In one embodiment, the cover member contains a polycarbonate-based resin.

In one embodiment, the cover member has a thickness of from 10 μm to 1,000 μm.

In one embodiment, the polarizer has a thickness of from 100 nm to 1,000 nm.

Advantageous Effects of Invention

According to the embodiment of the present invention, in the head-up display apparatus, the polarizing plate with a retardation layer is laminated on the housing inner side of the cover member configured to cover the opening portion of the housing, and the angle of reflection of the projection light output from the housing through the opening portion with respect to the windshield is set within a predetermined range. Accordingly, the head-up display apparatus that is excellent in viewability when the display screen is viewed through a pair of polarized sunglasses, and that is excellent in heat resistance can be achieved.

