JPH05104979A - Head up display - Google Patents

Abstract

PURPOSE:To provide a head up display having a uniform light intensity distribution for backlight afor a relatively large-surface display. CONSTITUTION:For radiating light generated from a light source 14 to a light receiving display element 16 effectively as a light flux without a light intensity distribution, an integrater lens 15 is inserted between the light source 14 and the light receiving liquid crystal display element 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle head-up display (HUD).

[0002]

2. Description of the Related Art HUD has recently been used as a method of displaying information to a driver in a vehicle. This is because the optical information projected from an information display source such as a liquid crystal display device is projected on a combiner including a half mirror,
The driver can read the information from the driving state without moving the line of sight.

FIG. 3 is a conceptual diagram showing the structure of such a vehicle-mounted HUD. Here, 31 is a driver's observation position, 32 is a combiner, 33 is a light beam containing information, 34 is an image forming (virtual image) position for distant display, 35 is a transmissive liquid crystal display element as a display, and 36 is a halogen lamp. And the like, 37 is a windshield, and 38 is a vehicle body.

The light emitted from the light source 36 passes through the transmissive liquid crystal display element 35, is applied to the holographic combiner 32 provided on the windshield 37 of the vehicle, and is reflected (diffracted) to the driver at the observation position 31. To be seen. At this time, the display information is recognized by the driver as a virtual image at the position 34.

[0005]

The information display source irradiating the combiner has heretofore been composed of a light source such as a halogen lamp as a backlight and a display body such as a transmissive liquid crystal display element. A diffuser plate was provided between them to ensure uniformity of the light intensity distribution of the displayed image.

However, for the purpose of displaying a relatively small screen, this diffuser plate is easy to handle and inexpensive and therefore easy to use, but a relatively large display screen (about 40 m) is used.
In the case of a display screen having a light emitting area of about 1.5 m or more) or more than about 1.5 times the light emitting area of the light source, the use of the diffuser plate can maintain the uniformity of the light intensity distribution, but has the drawback of lowering the brightness.

In order to be used in a head-up display for a vehicle, the brightness of the road surface during the daytime (about 3000 cd / m
² ) The above brightness is required. Moreover, the lamp that can be used for the vehicle must be small because of the problem of the storage space, and then the brightness cannot be obtained.

An object of the present invention is to solve the above-mentioned drawbacks of the prior art, and to provide a head-up display having a structure that has not been known hitherto. Is.

[0009]

The present invention has been made to solve the above-mentioned problems, and an information display source that generates information to be displayed as a light beam, and the light beam is reflected toward a viewer. A head-up display having a combiner arranged in an appropriate manner, wherein the light-up includes an integrator lens in a path leading to the combiner.

The information to be displayed here is appropriately selected according to its display application, and examples thereof include a vehicle speedometer and a tachometer.

The viewer is mainly the driver of the vehicle,
In addition, passengers and other passengers, and all of these can be included.

FIG. 1 shows a sectional view of the basic structure of the present invention. 12 is a HU provided on the vehicle window glass 11.
It is a D combiner. The information from the information display source 13 is reflected by the combiner and irradiated to the viewer 17.

Here, as the combiner, one having a dielectric enhanced reflection film made of TiO ₂ , ZrO ₂ or, in addition to these, SiO ₂ or the like, or one provided with a hologram film on a vehicle window glass inner surface side There is.

In particular, because of the simplicity of the optical element and the abundance of added functions, the combiner is
Preference is given to using holograms. This holographic combiner can have not only a reflection function (diffraction function) but also a lens function, so that optical information can be diffracted in the driver's visual field direction, or an optical system such as a lens is used. Instead, it is possible to form an image at an arbitrary position. Another feature is that a large-screen display image can be obtained with high brightness without impairing the foreground brightness.

Although such a combiner may be provided separately from the window glass, it is preferably used by being attached to the window glass of the vehicle because of its simple structure. Particularly, from the viewpoint of protecting the film forming the combiner. It is better to use it by enclosing it inside a window glass which is a laminated glass.

The information display source in the present invention has a function of emitting light to display, and as a typical example, a so-called light-receiving type display element 16 such as a liquid crystal display element is provided in a hot cathode tube (HCT) or fluorescent. There is also a combined use of a light source 14 including a display tube (VF), a tungsten lamp, a halogen lamp, a metal halide lamp, and an LED.

As the liquid crystal display element, a transmission type twisted nematic type liquid crystal display element, a super twisted nematic type liquid crystal display element and the like can be preferably used. Alternatively, instead of using the light-receiving display element, a light-shielding mask having a specific shape and a light source may be combined.

In the present invention, the integrator lens 15 is provided between the light source 14 and the light-receiving display element 16 in order to irradiate the light-receiving display element with the light emitted from the light source efficiently and as a light flux without unevenness in light intensity. Insert. Here, the integrator lens is used to eliminate uneven light intensity of a lamp or the like, and refers to an optical system such as a lens or a mirror having a function of collecting a light flux within a predetermined range without causing light loss as much as possible. ..

For example, a plurality of columnar lenses made of a transparent material such as glass and plastic and having spherical end faces are bundled (common name: fly eye), or a plurality of cylindrical lenses are combined in parallel, and One with the arrangement directions orthogonal to each other on the lower surface (common name: micro-cylinder lens), one with random arrangement of optical fibers (common name: bundle fiber), one with a combination of multiple convex and concave lenses, and refraction in the optical axis cross section of the transparent body Examples thereof include various configurations such as a graded index type lens and an aspherical lens having different ratios.

Further, it is not limited to a transparent body, but may be a mirror or the like, and a parabolic integrator mirror having a plurality of inclinations is exemplified. Holograms can also be used as these lenses and mirrors. In the case of a hologram, either a transmission hologram or a reflection hologram can be used, and an image hologram recording an image of a diffusion plate is preferable in practice.

[0021]

EXAMPLES Examples will be described below according to the present invention.

FIG. 2 shows a sectional view of the display information source of the head-up display of the present invention. Reference numeral 21 denotes a housing, which also has a function of supporting each member. 22 is a lamp socket, 2
3 is a halogen lamp with an elliptical mirror (100W), 24 is a heat ray cut filter, 25 is an integrator lens,
26 is an interference filter for wavelength selection (λ = 543 nm), 2
Reference numeral 7 is a polarizing filter, and 28 is a super twisted nematic liquid crystal display element.

The light beam condensed to 15 mmφ from the light source is uniformly expanded to 70 mm square by the integrator lens 25, and is applied to the liquid crystal display element 28. The structure of the integrator lens used here has a cross section of 5 mm square and a length of 18 mm.
This is a bundle of nine mm-shaped columnar lenses (three in each of the vertical and horizontal directions). With this, the luminance immediately before the surface of the liquid crystal display element is 5000 cd / cm ² , and the light intensity unevenness is only 18%. In the past, instead of an integrator lens, a simple magnifying lens and a diffusing plate were used to create a uniform light beam. In that case,
For example, the unevenness of light intensity can be made equal to 18% by stacking three pieces of # 600 ground glass, but the brightness is reduced to about 1/8.

The heat ray cut filter 24 inserted between the halogen lamp 23 and the integrator lens 25 is required when the light source is an incandescent light source such as a halogen lamp, and is usually a heat ray absorbing glass. And glass with heat ray reflective coating is used.

Furthermore, when the wavelength selection interference filter 26 is inserted between the integrator lens 25 and the liquid crystal display element 28, the information to be displayed is given a specific color, which is effective for the viewer to easily recognize. In general, a glass substrate coated with a dielectric interference film is generally excellent in wavelength selectivity and easy to use, but since it is expensive, colored glass, resin film, hologram or the like can be used instead.

Although the liquid crystal display element 28 is provided with a polarization filter 27 on the light source side, it is usually preferable that a polarization filter film is closely attached to the liquid crystal display element substrate. When the unevenness of the light intensity distribution cannot be preferably improved by the integrator lens, a diffusing plate may be further placed at the place where the polarization filter 27 of FIG. 2 is inserted.

In this embodiment, the total length of the head-up display housing was about 250 mm. For automobiles, it is preferable to further reduce the size in order to mount it in the instrument panel. For this purpose, it is desirable to insert an optical component such as a lens, a mirror, or an optical fiber between the integrator lens and the liquid crystal display element to refract or reflect the optical path length to shorten the total length.

[0028]

According to the present invention, as an illuminating device for a display of a vehicle head-up display, an integrator lens is provided in the light path of the illuminating device, so that the backlight is a relatively large screen display image. It has an effect that the light intensity distribution can be made uniform.

[Brief description of drawings]

FIG. 1 is a sectional view showing a basic configuration of the present invention.

FIG. 2 is a sectional view of an embodiment according to the present invention.

FIG. 3 is a conceptual diagram showing a conventional HUD.

[Explanation of symbols]

 11 Vehicle window glass 12 Combiner 14 Light source 15,25 Integrator lens 16 Light-receiving display element 23 Halogen lamp 28 Liquid crystal display element

Claims (1)

[Claims] 1. A head-up display having an information display source for generating information to be displayed as a light beam, and a combiner arranged to reflect the light beam toward a viewer. A head-up display characterized by being equipped with an integrator lens in the route to the end.