JP2001013451A - Magnified display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress an unnecessary picture from being formed and to enhance visibility. SOLUTION: This magnified display device is constituted so that the inclined part 11a of a Fresnel lens 11 having positive power in front of a display unit 12 is formed to be aspherical and the optical axis J thereof is positioned outside the edge part. Then, the lens 11 is disposed by being inclined in a front and a back direction so that the optical axis J side is positioned at the upper side of the edge part when the lower end of the lens 11 is near to a viewer and positioned at the lower side of the edge part when the upper end of the lens 11 is near to the viewer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an enlarged display device in which a Fresnel lens having a positive power is arranged in front of a display to enlarge and display the display content of the display.

[0002]

2. Description of the Related Art Conventionally, for example, an instrument for a vehicle is shown in FIG.
As shown in FIG. 0 (A), a Fresnel lens 1 having a positive power is arranged such that its optical axis J coincides with substantially the center of a display surface 2 a of a display 2.

As shown in FIGS. 11A and 11B, a Fresnel lens 1 has a structure in which a basic curved surface R centered on an optical axis J is finely divided and joined, as is well known. It is composed of a slope portion 1a having a surface shape substantially equal to the divided basic curved surface, and a vertical portion 1b for joining the adjacent slope portions 1a, and is substantially equivalent to an ordinary thick magnifying lens. Performance can be realized in a planar manner with a smaller thickness.

[0004] The driver D looks through the Fresnel lens 1 and looks at the display surface 2a of the display device 2 to obtain a display device shown in FIG.
The image F of the display content on the display surface 2a shown in FIG.
As shown in (C), the enlarged display image (virtual image) F is enlarged.
'Can be seen.

[0005]

By the way, in such a conventional enlarged display, as shown in FIG. 12, an unnecessary image is reflected on the Fresnel lens 1 (a stripe pattern is not shown). However, there is a problem that the visibility of the display is reduced due to the reflection phenomenon.

The reflection of the unnecessary image means that the driver and the steering wheel facing the display 2 and a part of the glass of the front side window glass or the rear window glass are the driver image d and the steering wheel image h. Is a phenomenon that is reflected on the Fresnel lens 1 as a glass image g.

The unnecessary images d, h, and g are
Since the display is superimposed on the enlarged display image F ′, the visibility of the display is reduced. In particular, when the vehicle is running in the daytime or under a relatively bright outdoor light, the driver and the steering wheel are steered. Since the brightness of the wheel, each glass, and the scenery seen through it is high, a bright unnecessary image is superimposed on the enlarged display image F ′, and the visibility is significantly reduced.

Therefore, in order to clarify the mechanism of such unnecessary images d, h, and g, ray tracing was performed on a light ray that generates an image near the driver D in the optical system arrangement shown in FIG.

By this ray tracing, the unnecessary images d,
h and g indicate that the image PQ near the driver D is the Fresnel lens 1
Is reflected on the slope portion 1a and forms an image, which is visually recognized by the driver D.

For example, an example of ray tracing when the Fresnel lens 1 is a plano-convex lens and is arranged so that a plane faces the driver D will be described. In the drawing, only the chief ray portion among the rays emitted from the object point is shown.

The image PQ in the vicinity of the driver D is an inverted image P'Q on the front side of the Fresnel lens 1 because the inclined surface 1a of the Fresnel lens 1 reflects light rays back and functions as if it were a concave mirror. ′, And this image P
'Q' is visually recognized by the driver D as an unnecessary image.

SUMMARY OF THE INVENTION The present invention has been made in view of such conventional problems, and has as its object to provide an enlarged display image capable of suppressing generation of an unnecessary image and improving visibility.

[0013]

In order to achieve the above object, according to the first aspect of the present invention, a Fresnel lens having a positive power is disposed in front of a display to enlarge the display content of the display. In the enlarged display device, the optical axis of the Fresnel lens is located outside including the edge of the Fresnel lens, and when the lower end of the Fresnel lens is close to the viewer, the optical axis side of the Fresnel lens has the edge. On the upper side,
When the upper end of the Fresnel lens is close to the viewer, the Fresnel lens is inclined in the front-rear direction so that the optical axis side is located below the edge, and the inclined portion of the Fresnel lens is formed as an aspheric surface. Is the gist.

According to a second aspect of the present invention, the curvature of the Fresnel lens is such that the curvature at the place where the distance between the Fresnel lens and the display surface of the display is large is smaller than the curvature at the place where the distance is small. Make a summary.

Further, the invention according to claim 3 is characterized in that the Fresnel lens is arranged so as to be attached to the surface of a protective cover obliquely provided in the front-rear direction in front of the display. .

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of an enlarged display device according to the present invention will be described with reference to the drawings, applied to a vehicle display.

In FIG. 1A, 11 is a Fresnel lens, and 12 is a display surface 12a facing the Fresnel lens 11.
Is a visual axis of the driver D toward the center of the display surface 12a, and the Fresnel lens 11 and the display 12
Is unitized by a housing (not shown),
On the display surface 12a, for example, an image F such as road information of a navigation system as shown in FIG.
As shown in FIG. 1 (C), an enlarged display image F ′ obtained by enlarging by the Fresnel lens 11 is obtained.

The Fresnel lens 11 is shown in FIG.
As shown in (B), it is composed of a slope portion 11a and a vertical portion 11b joining the adjacent slope portions 11a, and has a positive power in front of the display 12. Also, the optical axis J
(Rotation center of Fresnel lens 11) is Fresnel lens 1
One that is located outside in the sense including one edge is used.
Further, the Fresnel lens 11 is arranged to be inclined in the front-rear direction (upward).
Is arranged so that the optical axis J is located above the Fresnel lens 11 when the lower part of the lens is closer to the viewer (driver D), and when the upper part of the Fresnel lens 11 is closer to the viewer.
Are located below the Fresnel lens 11. Further, the inclined portion 11a of the Fresnel lens 11 has a surface shape in which an aspherical surface R 'whose curvature decreases from the upper side to the lower side of the Fresnel lens 11 is finely divided and joined.

When the slope 11a of the Fresnel lens 11 has the normal direction of all the slopes 11a facing upward as shown in FIG. 3, for example, an arbitrary point N on the image PQ near the driver D Is reflected on the slope 11a,
An upward one as shown by rays n1 and n2, and a ray n3
As shown in (1), since the light is reflected in any direction in which light is guided while totally reflecting inside the Fresnel lens 11, the light beams n1, n2, and n3 do not reach the driver D side. Can prevent generation of an unnecessary image.

Further, when the image near the driver D, which is an unnecessary image, is small, that is, the vehicle window is small and the painted color of the ceiling is a dark color under actual use conditions, so that it is practically acceptable even if the image is reflected as an unnecessary image. In such a case, or when an eave-shaped hood is provided on the front surface of the display 12, the optical axis J of the Fresnel lens 11 is
1 can be provided on the upper edge of the Fresnel lens 11 instead of on the upper side. In FIG. 4, no unnecessary image is generated on the slope 11a below the optical axis J of the Fresnel lens 11 for the reason described above. 4
As shown in the ray tracing, it is the point S that is not on the image PQ that emits reflected light that reaches the driver D side, and light rays from the image PQ near the driver are not allowed to reach the driver D side. For,
No unnecessary image is generated.

On the other hand, if the Fresnel lens 11 is tilted in the front-rear direction, the distance between the display surface 12a and the Fresnel lens 11 becomes non-uniform, which causes the distortion of the enlarged display image F 'to be enlarged.

This is because when the object inside the focal point of the Fresnel lens 11 is magnified and observed through the Fresnel lens 11 having a positive power, the Fresnel lens 1
This is because the larger the curvature of 1 and the larger the distance between the Fresnel lens 11 and the object, the larger the magnification.

Therefore, as shown in FIG. 5 (A), when the driver D observes the display contents by arranging the Fresnel lens 11 based on a curved surface having a constant curvature = spherical surface in a forward and backward direction as shown in FIG. The image F on the display surface 12a shown in FIG.
As shown in (C), the Fresnel lens 11 and the display surface 12
On the lower side where the distance to a is large, the enlarged display image F 'becomes larger, so that a distortion occurs such that the lower side expands, and the visibility of display is impaired.

Therefore, an aspherical surface R 'having an aspheric surface R' whose curvature becomes smaller from the upper side to the lower side of the Fresnel lens 11 is finely divided and joined to each other.
By doing so, it is possible to suppress distortion to a level that causes no practical problem.

That is, the slope 11a of the Fresnel lens 11
Display surface 12a and Fresnel lens 1
The enlargement magnification can be made substantially constant by making the curvature at the place where the distance from the distance 1 is large as compared with the curvature at the place where the distance is small, and the occurrence of distortion can be suppressed to a level that causes no practical problem. .

[0026]

Embodiment 1 Next, Embodiment 1 of the enlarged display device of the present invention will be described below.

FIG. 6 is an enlarged view of the 2 inch liquid crystal display 12, and the distance from the display surface 12a to the driver D is 8 points.
00 mm, Inclined surface 1 having an aspheric surface R 'represented by the following equation as a basic curved surface:
The Fresnel lens 11 having 1a was used. In the above equation, Z = sag of a plane parallel to the optical axis J, h = distance from the optical axis J, cuy = 0.00445, K = −9.672, A =
-0.455E-8 and B = 0.699E-11.

FIG. 7A shows an image of the display surface 12a, and FIG. 7B shows an enlarged display image F 'of the display surface 12a enlarged by such a Fresnel lens 11.

As a result, an enlarged display image F 'having an average magnification of about 1.15 times was obtained. At this time, strictly speaking, there is a distortion that the vertical direction is slightly longer than the horizontal direction, but actually, the driver D does not notice it. In addition, no unnecessary image was observed, and an enlarged display image F ′ having good visibility was obtained.

[0030]

Embodiment 2 Next, Embodiment 2 of the enlarged display device of the present invention will be described below.

FIG. 8 shows a circular meter (speedometer or the like) having a diameter of 50 mm as a display 12 and a scale thereof on a display surface 1.
2a, the driver D and the display surface 12
The distance to a is 800 mm, Inclined surface 11a having an aspherical surface R 'represented by
Was used. As shown in FIG. 8, the Fresnel lens 11 is arranged along the driver-side surface of the protective cover 12b of the display device 12. In the above equation, Z = sag of a plane parallel to the optical axis J, h = distance from the optical axis, cuy = 0.00681, K = -1.84.
3, A = -0.773E-7, B = 0.185E-11
And

FIG. 9A shows an image corresponding to the shape of the display surface 12a, and FIG.
1 shows an enlarged display image F ′ corresponding to the shape of the display surface 12a enlarged by 1.

As a result, an average magnification of about 1.15 was obtained. In this case, similarly to the first embodiment, there is a distortion that the vertical direction is slightly longer than the horizontal direction, but the driver D does not actually notice. Also,
No unnecessary image was observed, and an enlarged display image F ′ with good visibility was obtained.

As described above, in the enlarged display device of the present invention, the optical axis J is positioned outside the meaning including the edge of the Fresnel lens 11, and the Fresnel lens 11 is arranged to be inclined in the front-rear direction. If the lower part of the Fresnel lens 11 is close to the viewer (driver D) as shown in FIG. 1C, the optical axis J is tilted as shown in FIG.
Are arranged above the Fresnel lens 11, and when the upper part of the Fresnel lens 11 is close to the viewer, the optical axis J is arranged so as to be located below the Fresnel lens 11. Eleven unnecessary images are prevented from being generated. Also, the curvature of the Fresnel lens 11 is
By making the curvature where the distance between the Fresnel lens 11 and the display surface 12a of the display 12 is large smaller than the curvature where the distance is small, it is possible to reduce the distortion of the enlarged display image F '.

At this time, the Fresnel lens 11 is designed in any way with the conventional Fresnel lens 11 and other magnifying lenses.
The problem can be solved without difficulty in manufacturing and using. In the first and second embodiments, the application to a display for a vehicle is described. However, it is needless to say that the present invention is also useful for other industrial enlarged display devices such as a display for an information device. .

[0036]

As described above, in the enlarged display device of the present invention, the Fresnel lens is located outside the edge of the Fresnel lens, and when the lower end of the Fresnel lens is close to the viewer, the Fresnel lens is closed. When the optical axis side of the lens is above the edge and the upper end of the Fresnel lens is close to the viewer, the Fresnel lens is tilted in the front-rear direction so that the optical axis side is located below the edge, and the inclination of the Fresnel lens By forming the portion with an aspherical surface, generation of an unnecessary image can be suppressed and visibility can be improved.

[Brief description of the drawings]

FIGS. 1A and 1B show an enlarged display device according to an embodiment of the present invention, in which FIG. 1A is an optical arrangement diagram of the enlarged display device, FIG. 1B is a partially enlarged view in which a Fresnel lens is arranged, and FIG. FIG. 4D is a front view of a Fresnel lens showing an example of an enlarged display image, showing a front view of a display surface showing an example of an image.

FIG. 2A is a cross-sectional view of a Fresnel lens,
(B) is a rear view of the Fresnel lens.

FIG. 3 is an optical explanatory diagram for explaining a principle of preventing unnecessary image generation.

FIG. 4 is an optical explanatory diagram for explaining that an image near the driver is not an unnecessary image.

5A is an optical explanatory diagram for explaining a factor that causes distortion in an enlarged display image, FIG. 5B is a front view of the image before enlarged display, and FIG. 5C is an image in an enlarged display state; FIG.

FIG. 6 shows an enlarged display device according to Embodiment 1 of the present invention, and is an optical layout diagram of the enlarged display device.

FIG. 7A is a front view of an image before enlarged display.
(B) is a front view of the image in the enlarged display state.

FIG. 8 shows an enlarged display device according to a second embodiment of the present invention, and is an optical layout diagram of the enlarged display device.

FIG. 9A is a front view of an image before enlarged display.
(B) is a front view of the image in the enlarged display state.

10A and 10B show a conventional enlarged display device, FIG. 10A is an optical layout diagram of the enlarged display device, FIG. 10B is a front view of a display surface showing an example of a display image, and FIG. 10C is an example of an enlarged display image. It is a front view of the Fresnel lens shown.

FIG. 11A is a sectional view of a Fresnel lens.
(B) is a rear view of the Fresnel lens.

FIG. 12 is also a front view of the Fresnel lens in a state where an unnecessary image is reflected.

13A is an optical explanatory view showing the principle of generation of an unnecessary image, FIG. 13B is an optical path diagram inside a Fresnel lens in which a portion surrounded by FIG. 13A is enlarged, and FIG. Figure 1)
FIG. 3 is an optical path diagram inside a Fresnel lens in which a portion surrounded by (a) of FIG.

[Explanation of symbols]

 11 Fresnel lens 11a Slope 12 Indicator J Optical axis

Continued on the front page (72) Inventor Shuichi Ogawa 2-1910 Nisshincho, Omiya-shi, Saitama Kansai Co., Ltd. 72) Inventor Toshihisa Higuchi 5-9-1, Minami-Nagasaki, Toshima-ku, Tokyo F-term in Fujii Optical Co., Ltd. 5G435 AA01 DD02 DD11 GG05

Claims (3)

[Claims] 1. A magnifying display device in which a Fresnel lens having a positive power is disposed in front of a display to magnify and display the display content of the display, wherein the optical axis of the Fresnel lens is an edge of the Fresnel lens. When the lower end of the Fresnel lens is closer to the viewer, the optical axis side of the Fresnel lens is above the edge, and when the upper end of the Fresnel lens is closer to the viewer, the optical axis is An enlarged display device, wherein the Fresnel lens is inclined in the front-rear direction so that the side is located below the edge, and the inclined portion of the Fresnel lens is formed by an aspheric surface. 2. The curvature according to claim 1, wherein the curvature of the Fresnel lens is smaller when the distance between the Fresnel lens and the display surface of the display is large than when the distance is small. Magnifying display. 3. The device according to claim 1, wherein the Fresnel lens is disposed so as to be attached to a surface of a protective cover obliquely provided in a front-rear direction in front of the display. Display device.