Optical: systems and elements – Single channel simultaneously to or from plural channels – By partial reflection at beam splitting or combining surface
Reexamination Certificate
2003-03-07
2004-12-28
Mack, Ricky (Department: 2873)
Optical: systems and elements
Single channel simultaneously to or from plural channels
By partial reflection at beam splitting or combining surface
C359S640000, C359S634000
Reexamination Certificate
active
06836369
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a head-up display, more particularly, to a head-up display adaptable for use in vehicles or motorcars.
2. Description of the Related Art
Demand for human-machine interfaces of images that are excellently discernible and impose little burden on a driver is expected to increase due to the diversity in in-vehicle display information and the plentifulness thereof. In particular, the need for a field of safe driving aid in which view assistance information, visual information, and others are given as the contents of display is expected to increase. For effective communication of the information, preferably, a head-up display capable of presenting a large-size image far away, and superposing one image on another is expected to be adopted.
The head-up display includes an optical unit placed on an installment panel in a vehicle compartment. The optical unit consists mainly of a display device such as a liquid crystal display or a CRT, a reflecting mirror such as a concave mirror, and a dustproof cover. Light coming from the display device is reflected from the reflecting mirror. The light then passes through the dustproof cover that is laid over an opening, and falls on a windshield. The incident light is reflected from the windshield, whereby display information is presented as a virtual image, which is formed forwards beyond the windshield, to a driver. In order to increase the size of the virtual image displayed ahead of the driver, it is necessary to increase the width of a light path at the reflecting mirror and the width of a light path at the display device. This leads to an increase in the size of the optical unit.
However, the optical unit must be small in size in order to guarantee easy mounting of it on the installment panel.
Japanese Unexamined Patent Application Publication No. 6-55957 discloses a head-up display having an optical unit composed mainly of a display device and N (for example, three) deflecting means. A light path between the display device and the first deflecting means and a light path between the second and third deflecting means intersect on a horizontal plane.
The width of the path of light that is deflected by a deflecting means immediately before emerging from the optical unit must be equal to the width of a path of light formed by the conventional art. Furthermore, since a large number of deflecting means is employed, the requirement of a compact design cannot be met because of the space needed to accommodate the deflecting means.
Moreover, Japanese Unexamined Patent Application Publication No. 9-318906 discloses a head-up display having a resin or glass transparent member molded in the form of a block within which light is reciprocated.
However, even in this case, the width of the path of light at a deflecting means immediately before emerging from an optical unit must be equal to the width of a path of light formed by the conventional art. Furthermore, it is very difficult to mold the block so that the block is optically homogeneous.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a head-up display capable of displaying a large-size virtual image far from the view point without deterioration in display quality despite the compact design of the optical unit.
According to the first aspect of the present invention, there is provided a head-up display in which a prism is located on a light path between a display device, which emits light of a plurality of wavelength-bands, and a view point. Herein, the position in the display device which emits light of a certain wavelength-band and the position therein which emits light of another wavelength-band are made different from each other by a distance d determined in consideration of the difference between the paths of the light rays of different wavelengths.
The position of light having a certain range and the position of light having another range on the virtual image from the view point are made different from each other by an angle |&phgr;
01
−&phgr;
02
| which is within a permissible range.
Consequently, the problem wherein images formed with light rays having different wavelengths and having passed through a prism are seen at different points can be solved. Since the prism is located on a light path, an optical unit can be designed compactly. Consequently, a head-up display capable of presenting a large-size virtual image without deterioration in display definition can be realized at low cost.
When, for example, a typical color display or any other display device having pixels which emit light of a plurality of wavelength-bands is employed, a signal generator according to an aspect V of the present invention can be used. The signal generator generates a signal representing an image in which a pixel emitting light of a first wavelength-band and a pixel emitting light of a second wavelength-band are made different from each other. Thus, the head-up display according to an first aspect is realized. The signal generator according to the fifth aspect is realized with a computer such as a microcomputer including, for example, an LCD or CRT interface. When the feature of the signal generator is realized with a computer, the signal generator can be realized as a program that runs in the computer. In this case, the program is recorded in a computer-readable recording medium such as a flexible disk, a magneto-optical disk, a CD-ROM, a hard disk, a ROM, or a RAM. If necessary, the program is loaded from the recording medium into the computer. Alternatively, the program may be loaded over a network.
In order to design an optical unit compactly, according to the second aspect of the present invention, an optical element is included for changing a light path between a display device and a prism. In this case, the positions of virtual images formed with light rays, of a plurality of wavelength-bands and emitted from the display device, by the optical element are made different from each other by a distance d. In order to make different the positions from each other by the distance d, as described in relation to the first aspect, the position at which light is emitted having a first wavelength-band and the position at which light is emitted having a second wavelength-band, in the picture information displayed on the display device, is made different from each other. Consequently, the positions of the virtual images can be made different from each other. The optical element is, for example, a concave mirror.
Consequently, since the prism is located on the light path, the optical unit can be designed compactly. A head-up display capable of presenting a large-size virtual image without deterioration in display definition can be realized at a low cost.
The light of a plurality of wavelength-bands can be emitted from one or a plurality of display devices. When a plurality of display devices is used, according to a third aspect of the present invention, an optical unit includes a plurality of display devices that emits light rays of a plurality of wavelength-bands and an optical element that synthesizes light rays emitted from the plurality of display devices. The positions of virtual images of the plurality of display devices, which are formed by the optical element, are made different from each other by a distance d. The plurality of display devices that emit light rays having the plurality of wavelength-bands according to the third aspect means a plurality of display devices that emit light rays of different wavelength-bands. A preferable method for separating the positions of virtual images from each other will be described below. Similar to the first and second aspects, the optical unit is made compactly and a large-size virtual image can be displayed, because the prism is located on the light path. Accordingly, the problem wherein images which are formed with light rays of different wavelength-bands are seen at different points by passing through the prism can be solved. Co
Ando Hiroshi
Fujikawa Takayuki
Kakizaki Masaru
Yasuda Kazuya
Denso Corporation
Mack Ricky
Posz & Bethards, PLC
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