# US 10,768,418 B2 · Head-up display device

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- Number: US 10,768,418 B2
- Document ID: US10768418B2
- Status: Granted
- Kind: B2
- Application number: 16/177,246
- Filed: 2018-10-31
- Published: 2019-05-02
- Granted: 2020-09-08
- Earliest claimed: 2017-11-02
- Assignees: Yazaki Corporation
- Applicants: Yazaki Corporation
- Inventors: Noriaki Narushima
- Web page: https://patentgrep.com/patent/US10768418B2

## CPC

- G02B 27/0101: {characterised by optical features (G02B27/0172 takes precedence)}
- B60K 35/22: Display screens
- B60K 35/23: Head-up displays [HUD] (optical aspects of head-up displays G02B27/01)
- G02B 27/0927: {Systems for changing the beam intensity distribution, e.g. Gaussian to top-hat}
- G02F 1/133603: {with LEDs}
- B60K 2360/1523: Matrix displays
- B60R 2300/205: using a head-up display
- G02B 2027/0118: {comprising devices for improving the contrast of the display / brillance control visibility}
- G02F 1/133607: {the light controlling member including light directing or refracting elements, e.g. prisms or lenses}
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- B60K: ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
- G02F: OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- B60R: VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR

## Abstract

A head-up display device has a backlight unit configured to illuminate a liquid crystal panel from a back side. The backlight unit has an optical condenser configured to condense the light emitted from a light source toward the liquid crystal panel, and a microlens array arranged in an optical path between the optical condenser and the liquid crystal panel to diffuse the light condensed by the optical condenser. The microlens array has a light emission face arranged in a position optically conjugated with an eyebox to emit the light incident from the optical condenser.

## Claims

### Claim 1

A head-up display device comprising:
a display that emits a display light corresponding to a display image, the head-up display device allowing a driver to visually recognize a virtual image displayed in front of a display member depending on the display image in a driver's visible area in a vehicle by projecting the display image displayed on the display onto the display member through an optical system of the vehicle, wherein
the display has a transmission type liquid-crystal display element, and a backlight unit that illuminates the liquid-crystal display element from a back side thereof,
the backlight unit has a single light source, an optical condenser that condenses light emitted from the light source toward the liquid-crystal display element, and an optical member arranged in an optical path between the optical condenser and the liquid-crystal display element to diffuse the light condensed by the optical condenser,
the optical member has a light emission face arranged in a position optically conjugated with the visible area to emit the light incident from the optical condenser, and the light emission face has a center axis, and
the optical condenser is asymmetric with respect to the center axis such that illuminance distribution of light emitted from the light emission face varies in a vertical direction of the light emission face in order to provide a constant luminance distribution in the vertical direction of the visible area, and has a single lens face which is a convex free curved surface.

### Claim 2 (depends on 1)

The head-up display device according to claim 1, wherein
the optical condenser is formed such that an optical length from the light source to the curved surface is shortened by reducing a curvature of the lens face corresponding to a position for decreasing illuminance of the light emission face in order to decrease the illuminance of the light emission face in a side optically conjugated with an upper side in the vertical direction of the visible area.

### Claim 3 (depends on 1)

The head-up display device according to claim 1, wherein
the optical condenser is formed such that an optical length from the light source to the curved surface is lengthened by increasing a curvature of the lens face corresponding to a position for increasing illuminance of the light emission face in order to increase the illuminance of the light emission face in a side optically conjugated with a lower side in the vertical direction of the visible area.

### Claim 4 (depends on 1)

The head-up display device according to claim 1, wherein
the optical condenser is an optical condensing lens having an incident face concaved toward a side of the light source, and a light emission face formed at a side of the optical member and emitting the light incident from the incident face to diffuse in a direction separated from an optical axis direction, and is formed such that the incident face has a center axis positioned in a lower side of the vertical direction of the light emission face.

### Claim 5 (depends on 1)

The head-up display device according to claim 1, wherein
the optical member has a plurality of microlenses arranged in a grid shape, and
each of the microlenses has a lens face which is a convex or concave curved surface.

### Claim 6 (depends on 2)

The head-up display device according to claim 2, wherein
the optical member has a plurality of microlenses arranged in a grid shape, and
each of the microlenses has a lens face which is a convex or concave curved surface.

### Claim 7 (depends on 3)

The head-up display device according to claim 3, wherein
the optical member has a plurality of microlenses arranged in a grid shape, and
each of the microlenses has a lens face which is a convex or concave curved surface.

### Claim 8 (depends on 4)

The head-up display device according to claim 4, wherein
the optical member has a plurality of microlenses arranged in a grid shape, and
each of the microlenses has a lens face which is a convex or concave curved surface.

### Claim 9

A head-up display device comprising:
a display that emits a display light corresponding to a display image, the head-up display device allowing a driver to visually recognize a virtual image displayed in front of a display member depending on the display image in a driver's visible area in a vehicle by projecting the display image displayed on the display onto the display member through an optical system of the vehicle, wherein
the display has a transmission type liquid-crystal display element, and a backlight unit that illuminates the liquid-crystal display element from a back side thereof,
the backlight unit has a single light source, an optical condenser that condenses light emitted from the light source toward the liquid-crystal display element, and a diffuser arranged in an optical path between the optical condenser and the liquid-crystal display element to diffuse the light condensed by the optical condenser, and
the diffuser has a light emission face arranged in a position optically conjugated with the visible area to emit the light incident from the optical condenser, and is arranged with an inclination against an optical axis direction of the light emission face such that illuminance distribution of light emitted from the light emission face varies in a vertical direction in order to provide a constant luminance distribution in a vertical direction of the visible area.