Computer graphics processing and selective visual display system – Image superposition by optical means
Reexamination Certificate
1997-06-30
2003-01-07
Lieu, Julie (Department: 2632)
Computer graphics processing and selective visual display system
Image superposition by optical means
C345S008000, C359S600000, C359S631000, C359S632000, C359S633000, C340S980000
Reexamination Certificate
active
06504518
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a head-up display suited for mounting on vehicles such as cars and vessels.
DESCRIPTION OF RELATED ART
To provide navigation information or the like for a car driver (observer), there is used a head-up display comprising a combiner to be arranged in front of the observer and a display element which projects image displaying light from its image displaying face. By changing the optical path of the image displaying light by the combiner, a virtual image, that is a subject of observation, is formed in front of the combiner. A landscape in front of the combiner can be visually recognized by the light which passes through the combiner.
When the optical path of the image displaying light from the display element is changed directly by the combiner, the distance from the observer to the position, at where the virtual image is formed, shortens, because the optical path of the image displaying light between the display element and the observer's pupil shortens. This extends the time required to change the observer's condition from watching the actual landscape in front of the car to recognizing the virtual image. This is undesirable for vehicle driving. When the distance between the display element and the combiner is increased to lengthen the optical path of the image displaying light from the display element to the observer's pupil, the problem of increased size of the head-up display is generated.
To resolve this problem, a mirror facing the image displaying face can be provided. By introducing image displaying light to the combiner by reflecting the image displaying light by the mirror's reflecting surface, the optical path of the image displaying light can be lengthened in a given space without increasing the size of the head-up display.
However, the reflecting surfaces of the conventional mirrors are flat or concave. Therefore, the external light, such as solar light, which passes through the combiner, is focused in a narrow range on the image displaying face by being reflected by the mirror. The infrared rays contained in the external light are then absorbed in the image displaying face, resulting in heat concentration on the image displaying face and hence the problems of displaying performance reduction etc are generated.
The object of the present invention is to provide a head-up display free of the above-described problems.
SUMMARY OF THE INVENTION
The present invention relates to a head-up display comprising a combiner to be arranged in front of an observer; and a display element which projects image displaying light from its image displaying face; wherein a virtual image, that is a subject of observation, is formed in front of the combiner by changing the optical path of the image displaying light by the combiner; and wherein an optical component facing the image displaying face is provided so that the image displaying light can be introduced to the combiner by changing the optical path of the image displaying light.
The present invention is characterized in that the optical component is capable of diverging incident light.
According to the constitution of the present invention, the external light, such as solar light, which passes through the combiner, is diverged on the optical path changing face of the optical component. Therefore, the external light does not focus in a narrow range, so that heat concentration on the image displaying face by the infrared rays contained in the external light is mitigated.
In the head-up display of the present invention, it is preferable that the optical path changing face of the optical component is arranged so as to be inclined with respect to the vertical direction to allow the image displaying light to ascend as the light goes forward by changing the optical path; and that the image displaying face is arranged so as to be inclined with respect to the vertical direction to allow itself to depart from the optical component as it descends.
By this constitution, the external light, such as solar light, which passes through the combiner, can be prevented from going toward the observer after its optical path is changed on the image displaying face.
In the head-up display of the present invention, it is preferable that the optical path changing face of the optical component change the optical path of the external light, which passes through the combiner, so that the external light does not again go to the combiner.
By this constitution, the external light can be prevented from reaching the observer's pupil.
According to the present invention, a head-up display of good visibility, which can reduce the amount of infrared rays contained in the external light absorbed in the image displaying face and can prevent the displaying performance reduction, can be provided.
In the head-up display of the present invention, it is preferable that the optical path of the image displaying light, which is projected from any one point of the display element, from the optical component to the combiner is located above the optical path of the image displaying light from the projection point to the optical component and also below the optical path of the image displaying light from the combiner to the observer's pupil.
By this constitution, the display element can be placed as close to the combiner as possible. Therefore, the head-up display can be made more compact, so that it is suited for installation in the narrow space inside a car compartment.
In the head-up display of the present invention, it is preferable that the combiner comprises a body, and a reflecting layer which covers one face of the body, that at least one side of the body is configured with a platy material made of synthetic resin, that the platy material is covered with a coating which is harder and smaller in thermal expansion coefficient than the platy material, that the reflecting layer is formed on the coating, that the reflecting layer is configured with a plurality of laminated films, which are smaller in thermal expansion coefficient than the platy material and have mutually different refractive indexes, and that each of the films has residual compressive stress at normal temperature.
According to the above-described constitution, the deterioration of the combiner due to swelling and solar light exposure can be prevented by covering the platy material of synthetic resin constituting the body by a coating which is harder and smaller in thermal expansion coefficient than the platy material. Because the reflecting layer, which is configured with a plurality of films, is formed on the coating, the reflecting layer can be prevented from cracking and peeling from the body. Thereby, the combiner is of high reflectance and high transparency. Moreover, because each of the films constituting the reflecting layer has residual compressive stress at normal temperature, internal tensile stress can be prevented from being exerted on the reflecting layer, even if the body is expanded, whereby the reflecting layer can be prevented from peeling and cracking.
In the head-up display of the present invention, it is preferable that the image displaying light is projected from a liquid crystal display element having a backlight device, that the light source for backlight of the liquid crystal display device has a fluorescent tube, a driving circuit for the fluorescent tube, a lead which connects the fluorescent tube to the driving circuit, and a support portion, that the light source for backlight is made as a unit attachable to, and detachable from a housing which houses the liquid crystal display element, that the fluorescent tube is supported by the support portion so that it is arranged in a space outside the support portion, that the driving circuit and the lead are arranged in a space inside the support portion, and that the outer surface of the support portion serves as a backlight reflecting surface which reflects the light beam for backlight generated by the fluorescent tube.
According to this constitution, replace
Kuwayama Yukiko
Nasu Ryutaro
Sugibuchi Toshihiko
Lieu Julie
Rader & Fishman & Grauer, PLLC
Shimadzu Corporation
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