JPH10138833A - Visibility magnifying device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a clouding phenomenon of a lens and to improve visibility by constituting at least a part in the vertical direction of a Fresnel concave lens having a side surface shape formed curved or bent in a concave shape to the front side of a vehicle. SOLUTION: A Fresnel concave lens 22 is formed in a shape curving a side surface shape in a concave shape to the front side of a vehicle in the vertical direction. A front surface 22a of the Fresnel concave lens 22 is formed in an irregular surface forming a lens, and a back surface 22b is formed in a flat surface. A prism 32 is formed in a concentric circle around an optical axis center 24 of the lens as its center on the irregular surface. The optical axis center 24 of the lens is set at a central position in the cross direction of the Fresnel concave lens 22 and on a position upward in the vertical direction. Width D of a non-lens surface 22c is made longer toward a lens lower part. Consequently, it is possible to reduce a clouding phenomenon and to improve visibility.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle field-of-view expanding device for mounting a concave Fresnel lens on a rear window of a vehicle to enlarge a rear field of view, and relates to a clouding phenomenon of a lens caused by mounting a concave Fresnel lens on an inclined rear window. Is prevented and visibility is improved.

[0002]

2. Description of the Related Art There has been proposed a vehicle view enlarging device in which a rear view is widened by mounting a Fresnel concave lens on a rear window of a vehicle (for example, Japanese Utility Model Application Laid-Open No. HEI-5-115).
No. 7-153302). As shown in FIG. 2, by attaching a Fresnel concave lens 14 made of resin or the like along the inner surface of the rear window 12 of the vehicle 10 as shown in FIG. A portion that becomes a blind spot in a direct view (a portion immediately below the vehicle, etc.) can be visually recognized through the Fresnel concave lens 14.

[0003]

Since the rear window of the vehicle is inclined, the non-lens surface 14a (FIG. 3 (b)) of the Fresnel concave lens 14 can be seen from the driver's viewpoint 16 as shown in FIG. Positional relationship, non-lens surface 14a
The diffused reflection line 18 from the lens is seen as a clouding phenomenon in the lens field of view, which deteriorates the visibility. In particular, in a general Fresnel concave lens having a constant plate thickness and a constant prism pitch, the width D of the non-lens surface 14a increases as the prism angle θ increases below the lens away from the optical axis center 14b of the Fresnel concave lens 14. Became inevitably longer and the cloudiness increased.

An object of the present invention is to solve the problems in the prior art and to provide a vehicular field-of-view enlargement device which improves the visibility by preventing the clouding phenomenon of the lens.

[0005]

A vehicle view enlarging device according to the present invention is constituted by a Fresnel concave lens having a side surface shape formed such that at least a part of the vertical direction is curved or bent concavely toward the front of the vehicle. The upper portion is mounted along a surface of the rear window of the vehicle, which is inclined obliquely downward toward the inside of the vehicle, and the lower portion is disposed so as to hang down from the rear window.

According to the present invention, the Fresnel concave lens is curved or bent in the vertical direction, and the lower part of the lens having a large prism angle is disposed so as to hang downward. It becomes hard to see from the viewpoint, and the cloudiness is reduced, so that the visibility can be improved. In addition, as shown in FIG. 4, the Fresnel concave lens is curved or bent in the vehicle cabin as compared with a case where the entire Fresnel concave lens is formed in a flat plate shape and is disposed in a state of hanging downward (two-dot chain line). The protrusion amount of the lens can be reduced, and the Fresnel concave lens can be arranged so as not to interfere.

The radius of curvature when the Fresnel concave lens is curved uses a constant radius of curvature or a combination of a plurality of radii of curvature (for example, an upper radius of curvature is shortened and a lower radius of curvature is lengthened). And so on).

[0008]

FIG. 1 shows an embodiment of the present invention. The vehicle view enlarging device 20 is configured by a Fresnel concave lens 22 made of a transparent resin or the like. Fresnel concave lens 2
Reference numeral 2 has a constant plate thickness d, a front shape is formed in, for example, a horizontally long rectangular shape, and a side shape is formed to be concavely curved toward the vehicle front side over the entire vertical direction. The Fresnel concave lens 22 has a front surface (a surface on the front side of the vehicle) 22a formed on an uneven surface forming a lens, and a rear surface 22b formed on a smooth surface. On the uneven surface, a prism 32 is formed concentrically around the optical axis center 24 of the lens. The prism pitch P is constant. The center 24 of the optical axis of the lens is set at the center position in the width direction of the Fresnel concave lens 22 and at an upper position in the vertical direction. The prism angle θ increases toward the lower part of the lens away from the center of the optical axis, and accordingly, the width D of the non-lens surface 22c increases toward the lower part of the lens.

The concave shape of the Fresnel concave lens 22 may be formed by bending a flat Fresnel concave lens, or by simultaneously forming the Fresnel concave lens using a mold having a curved shape. Can be.

The Fresnel concave lens 22 having the above-described configuration has an upper portion disposed along the inner surface 12a of the rear window 12 and attached with a transparent double-sided adhesive tape 26, and a lower portion hanging down from the rear window 12 (see FIG. 1). In the example of FIG. 1, the lower end of the Fresnel concave lens 22 hangs substantially vertically downward.) FIG. 5 shows a state in which the vehicle view enlarging device 20 is viewed from the vehicle interior side. (A) is Fresnel concave lens 2
2 attached to the rear window 12 using fasteners 38, 40 (double-sided adhesive tape is attached to the entire back surface) attached to the left and right of the upper part of FIG. Attached fastener 3
6 (a double-sided adhesive tape is attached on the entire back surface) to the rear window 12.

The Fresnel concave lens 22 has a thickness of 2 to 2.
If the outer shape is 3 mm and the outer shape is about 200 mm wide x 150 mm long, the weight is about 100 g, so as shown in Figs. 1 and 5, only the upper part is adhered with double-sided adhesive tape of an appropriate width, and the lower part is unsupported. But it can be supported enough. However, if necessary, anti-swaying measures such as supporting the lower portion of the Fresnel concave lens 22 on the rear window 12 with a support member can be taken.

According to the structure and arrangement of the Fresnel concave lens 22 as described above, the lower part of the Fresnel concave lens 22, which is liable to cause cloudiness, is separated from the rear window 12 and hangs downward. As shown, the non-lens surface 22c is arranged in a posture close to the horizontal plane, making it difficult to see from the driver's point of view, reducing the cloudiness and improving the visibility.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS When the entire Fresnel concave lens 22 is curved with a constant radius of curvature as in the embodiment of FIG. 1, if the radius of curvature is short, aberrations below the lens may increase. . FIG. 6 shows an embodiment of the present invention which solves this problem. This vehicle view enlarging device 34 includes:
The radius of curvature of the Fresnel concave lens 22 is set shorter on the upper side and longer on the lower side. In this example, the radius of curvature is changed in two steps, but may be changed in more steps or even steplessly. By changing the radius of curvature in this way, aberrations at the lower part of the lens are reduced. Also, compared to the case where the whole is curved with a constant radius of curvature,
The amount of protrusion of the lens in the vehicle interior can be reduced.

FIG. 7 shows still another embodiment of the present invention. In the vehicle view enlarging device 28, only the upper portion of the Fresnel concave lens 22 is curved, and the lower portion is formed in a flat plate shape and hangs downward. The radius of curvature of the upper curved portion can be changed in the same way as in FIG.

Even with such a structure and arrangement of the Fresnel concave lens 22, the lower part of the Fresnel concave lens 22, which is liable to cause the clouding phenomenon, is in a state of hanging downward.
The non-lens surface is arranged in a posture close to the horizontal plane, making it hard to see from the driver's viewpoint, and the white turbidity phenomenon is reduced and the visibility is improved. Further, the amount of protrusion of the lens in the vehicle compartment can be reduced as compared with the embodiment of FIG.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As a specific example of the Fresnel concave lens 22 shown in FIGS. 1, 6 and 7, as shown in FIG.
A Fresnel concave lens having a length of 120 mm, an optical axis center 24 at a position 17 mm from the upper end in the width direction, and a focal length of -217 mm was manufactured, and an experiment of a visual recognition state was performed by variously setting a curved state. The results are shown below. (Experiment 1) In the configuration of FIG. 1, when the whole was curved with a radius of 150 mm in the vertical direction, the amount of white turbidity was reduced. (Experiment 2) In the configuration of FIG.
Curving at 0 mm and curving the lower half with a radius of 250 mm reduced the cloudiness. (Experiment 3) In the configuration of FIG.
Curving at 0 mm and flattening the remaining 2/3 portion reduced the cloudiness.

In the above embodiment, the case where the whole or a part of the Fresnel concave lens is curved is shown. However, as shown in the vehicle view enlarging device 30 of FIG. It can also be formed in a side shape bent in the middle of the direction. Further, in the above-described embodiment, the case where the lower part of the Fresnel concave lens is arranged in a state of hanging vertically downward is shown. However, it is not always necessary to arrange the lower part of the Fresnel lens in a state of hanging vertically downward. You may.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of the present invention in which a Fresnel concave lens is entirely curved in a vertical direction, and is a cross-sectional side view taken along the optical axis of the Fresnel concave lens.

FIG. 2 is a view showing a field of view by a Fresnel concave lens.

FIG. 3 is a cross-sectional side view showing a conventional device and a partially enlarged view thereof.

FIG. 4 is a view for explaining a difference in the amount of protrusion of the Fresnel concave lens in the vehicle compartment between the case where the Fresnel concave lens according to the present invention is used and the case where the flat Fresnel lens is disposed vertically.

FIG. 5 is a perspective view showing an arrangement state of the vehicle view enlarging device 20 of FIG. 1 as viewed from the vehicle interior side.

FIG. 6 is a view showing another embodiment of the present invention in which the curvature radius of the curvature of the Fresnel concave lens is set to be shorter at the upper part and longer at the lower part, and is a cross-sectional side view taken along the optical axis of the concave Fresnel lens.

FIG. 7 is a view showing another embodiment of the present invention in which only the upper part of the Fresnel concave lens is curved, and is a cross-sectional side view taken along the optical axis of the Fresnel concave lens.

FIG. 8 is a perspective view showing an example of dimensions of a Fresnel concave lens used in the present invention.

FIG. 9 is a view showing another embodiment of the present invention in which a flat Fresnel concave lens is bent in the middle, and is a cross-sectional side view taken along the optical axis of the Fresnel concave lens.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Vehicle 20,28,30,34 View expansion device for vehicles 22 Fresnel concave lens

Claims (1)

[Claims] 1. A fresnel concave lens having a side surface shape formed by curving or bending concavely toward the front of the vehicle at least partially in the vertical direction, the upper part of which is directed obliquely downward inside the rear window of the vehicle. A view expanding device for a vehicle, which is mounted along an inclined surface and has a lower part disposed downwardly away from the rear window.