JPH05289618A - Image display device - Google Patents

Abstract

PURPOSE:To obtain a bright image and also to faithfully reproduce image colors in an image display device utilizing optical fibers even when the visual field angle is increased and the image is made in high precision by suppressing the reflection of external light not only in front of a display board, but also on the tip surfaces of the optical fibers. CONSTITUTION:A transparent plate 5 is provided on the front surface side of the display board 4 of which the tip surfaces 3 of the optical fibers 2 are exposed, and light absorbing layers 6 are formed on the front surface side of the transparent plate 5 except on light projection surfaces 7. The light absorbing layers 6, therefore, interrupts the light made incident on the tip surfaces 3 of the optical fibers 2 and the front surface of the display board 4 positioned more inside than the light absorbing layers 6 to increase the contrast ratio of the image and also prevent the external light from being mixed with projected image light, thereby obtaining the bright image and accurate image colors.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention exposes the front end surface of an optical fiber on which image light is incident from a focused rear end surface to a front side of a display substrate with a gap, and the image light entering from the rear end surface of the optical fiber. The present invention relates to an image display device capable of enlarging and displaying an image by emitting light to an enlarged region. More specifically, it relates to expansion of the contrast ratio of an image in an image display device using such an optical fiber.

[0002]

2. Description of the Related Art Image display devices using optical fibers as described above have been proposed in, for example, JP-A-56-8370, JP-A-58-214188, and JP-A-58-168081, and have a large screen. Since it is relatively thin, it is expected to be widely used as a large wall-mounted display device used as a display for remote conferences, stations, airports, department stores, etc.

By the way, as a defect in the image quality of the image display device using the optical fiber, in addition to the narrow viewing angle, the image is dark.

Image darkness is a problem that is also related to the viewing angle. That is, as the viewing angle becomes wider and the image can be observed from a wider range, the observed image becomes darker due to the diffusion of light. Further, if the viewing angle is narrowed to obtain the brightness of the image, the position where the image can be observed is limited, and the practicality of the image display device using the optical fiber becomes low.

The brightness of an image is basically governed by the amount of image light. Therefore, in order to obtain a bright image, it is sufficient to make the image light strong and increase the light amount thereof, but there is a limit to making the image light strong. Further, even if the amount of image light is large, the image perceived by human eyes may not necessarily be perceived as bright.

The reason why an image may not appear bright even if the amount of image light is increased is that the brightness of the image perceived by humans is greatly affected by the contrast ratio. That is, if the contrast ratio of an image is small, even an image with a large amount of light looks dark to the human eye, and conversely, if the contrast ratio is large, an image with a small amount of light looks bright.

Therefore, in order to obtain a bright image for human beings, it is an important point to increase the contrast ratio because the increase in the amount of image light is limited.

The contrast ratio is the ratio of the brightness when the maximum amount of light is emitted from the optical fiber, that is, the maximum brightness, to the brightness when the light emitted from the optical fiber is zero, that is, the minimum brightness. The maximum brightness is determined by the intensity of light supplied from the light source, but the minimum brightness varies depending on the influence of external light. In other words, the minimum brightness appears as the sum of the brightness of the front end surface of the optical fiber and the brightness of the front surface of the display substrate, which is caused by the reflection of external light, even if the light emitted from the optical fiber is zero.

Conventionally, in order to reduce the minimum luminance and increase the contrast ratio, a light absorbing layer has been provided on the front surface of the display substrate excluding the exposed end surface of the optical fiber.

[0010]

Although the contrast ratio is certainly improved by providing a light absorbing layer on the front surface of the display substrate, this light absorbing layer does not block the incidence of external light on the tip surface of the optical fiber. However, there is a problem that the reflection of external light on the tip surface of the optical fiber cannot be prevented. In particular, recently, there has been a demand for higher definition of images, and for that purpose, it is necessary to increase the number of optical fibers and arrange them densely. Will increase and reduce the contrast ratio. In addition, the reflection of external light from the tip surface of the optical fiber
When the image light is emitted from the front end surface, it may cause discoloration of the image due to mixing of the reflected external light with the emitted image light.

According to the present invention, in an image display device using an optical fiber, the reflection of external light is suppressed not only on the front surface of the display substrate but also on the front end surface of the optical fiber to expand the viewing angle and increase the definition of the image. It is also intended to obtain a bright image and faithfully reproduce the image color.

[0012]

To this end, in the present invention,
As shown in FIG. 1, the front end side of the display base 4 is exposed at the front end side 3 of a large number of optical fibers 2 on which image light is incident from the focused rear end face 1 with a gap. Is provided with a transparent plate 5, and the front surface region of the transparent plate 5 in the range of the effective emission angle θ of the light emitted from the tip surface 3 of the optical fiber 2 is left as the light emitting surface 7 on the front surface side of the transparent plate 5. The means of forming the light absorption layer 6 is taken.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a first embodiment of the present invention. As shown in the drawing, the front ends of a large number of optical fibers 2 whose rear ends are focused are mounted on a display substrate 4 with a space P therebetween. ing. Rear end face 1 of focused optical fiber 2
Is irradiated with image light from, for example, a liquid crystal video projector, and the image light incident from the rear end face 1 is guided through the optical fiber 2 and emitted from the front end face 3.

As shown in FIG. 2A, the focusing state of the optical fiber 2, that is, the focusing state of the rear end face 1 of the optical fiber 2 is generally a horizontal stack and a staggered stack in the vertical direction. However, as shown in FIG. 2B, a vertical and horizontal serial state may be adopted.

The tip of the optical fiber 2 is attached to the display board 4 with its tip surface 3 exposed at the front side of the display board 4 with a space P (distance between the centers of the tip surfaces 3). It is inserted into the hole penetrating the display substrate 4 from the rear surface side. Even if the tip surface 3 of the optical fiber 2 is slightly retracted from the front surface of the display substrate 4, the display substrate 4
Even if it is located on the same surface as the front surface of the
May be slightly projected from the front surface of.

The arrangement state of the front end face 3 of the optical fiber 2 is as shown in FIG. 3, and the focusing state of the rear end face 1 is shown in FIG.
In the case of the state of (a), as shown in FIG. 3 (a), there is a horizontal zigzag arrangement in a zigzag pattern in the vertical direction, and the tip surfaces 3 adjacent to each other are on the vertices of an equilateral triangle with P on each side. It will be placed in the state. In addition, the focusing state of the rear end face 1 is shown in FIG.
In the case of the state of (b), as shown in FIG. 3 (b), the vertical and horizontal series are arranged, and the tip surfaces 3 adjacent to each other are arranged on the corners of a square with P on each side. Becomes

A transparent plate 5 is provided on the front side of the display substrate 4, and the front end surface 3 of the optical fiber 2 exposed on the front side of the display substrate 4 is close to or in contact with the rear surface of the transparent plate 5.
In addition, the transparent plate 5 in this embodiment has a smooth surface on both the front surface and the rear surface.

The front surface of the optical fiber 2 and the transparent plate 5 may be integrally bonded with a transparent adhesive, but the transparent plate 5
In order to facilitate the replacement of the above, it is preferable not to join them together. However, the tip surface 3 of the optical fiber 2 and the transparent plate 5
If the gaps are integrally joined with a transparent adhesive, the light emitted from the front end surface 3 of the optical fiber 2 is less likely to be reflected when entering the transparent plate 5, and there is an advantage that the image can be brightened accordingly.

The material of the transparent plate 5 is not particularly limited as long as it is transparent, and for example, transparent glass or synthetic resin is used. However, a transparent synthetic resin is preferable from the viewpoints of lightness, resistance to cracking, workability, and the like. As the transparent synthetic resin, for example, polyvinyl chloride, polyester, polycarbonate, polymethylmethacrylate (PMMA) and the like can be used. Among them, PMM is preferable in terms of weather resistance, transparency and processability.
A is preferred.

A light absorbing layer 6 is provided on the front surface of the transparent plate 5 except for the light emitting surface 7. The light absorption layer 6 is provided on the front surface of the transparent plate 5, so that the display substrate 4 is provided.
Is located in front of the front surface of the optical fiber 2 and the front end surface 3 of the optical fiber 2, and plays a role of a sun visor that protects them from direct sunlight.

The range in which the light absorption layer 6 is provided is a range excluding the front surface region of the transparent plate 5 in the range of the effective emission angle θ of the light emitted from the tip surface 3 of the optical fiber 2. If the front surface region of the transparent plate 5 in the range of the effective emission angle θ is covered with the light absorption layer 6, the amount of image light emitted through the transparent plate 5 becomes too small and it becomes difficult to obtain a bright image.

As shown in FIG. 4A, the light absorption layer 6 leaves only the front surface area of the transparent plate 5 within the range of the effective radiation angle θ as the light emission surface 7, and covers all other areas. Is most preferred. However, as shown in FIG.
As shown in (c) and (d), it has a band shape or a grid shape, and the area outside the effective radiation angle θ is to some extent the light emitting surface 7
The light absorption layer 6 may be provided in a state of being included in. However, when the light emitting surface 7 includes a region outside the range of the effective radiation angle θ, it is preferable that 1/2 or more of the region outside the range of the effective radiation angle θ is covered with the light absorption layer 6.

The effective radiation angle is an angle determined as follows.

With the transparent plate 5 not provided, that is, with the front end surface 3 of the optical fiber 2 exposed to the front, the rear end surface 1 of the optical fiber 2 is made perpendicular to the rear end surface 1 by using a light source such as a slide projector. The intensity (luminance) of the light emitted from the tip surface 3 of the optical fiber 2 is measured using a measuring device such as a luminance meter. This measurement is performed by using the front surface of the display substrate 4 with the tip end surface 3 of the optical fiber 2 exposed as a screen, at substantially the same distance with respect to this screen, and changing the angle with respect to the front facing direction with the screen.

When the measurement result is represented by the luminance on the vertical axis and the angle of the measurement position (viewing angle) on the horizontal axis, a curve as shown in FIG. 5 is usually obtained. The brightness at the apex of this curve is the peak brightness L _p , and in the case of the ordinary optical fiber 2, the peak brightness L _p is at the viewing angle of 0. The value of the viewing angle when the luminance is 1/2 the value of the peak luminance L _{p is} the value of the effective radiation angle θ.

The effective radiation angle θ is usually governed by the difference in the refractive index between the core material and the sheath material used in the optical fiber 2, and the larger the difference, the larger the effective radiation angle θ.
In the case of the optical fiber 2 made of synthetic resin, this value is generally around 10 degrees (about 5 to 15 degrees). Further, the value of the effective radiation angle θ is greatly influenced by the surface roughness and shape of the rear end face 1 and the front end face 3 of the optical fiber 2, and, for example, when the surface is rough, the effective radiation angle θ becomes large.

The effective radiation angle θ is preferably large in order to increase the viewing angle, but is preferably small in order to increase the contrast ratio. Particularly, in the present invention, as will be described later, the selection range of the thickness of the transparent plate 5 becomes wider as the effective radiation angle θ becomes smaller. Therefore, the effective radiation angle θ is preferably small. Therefore, the rear end face 1 of the optical fiber 2
It is preferable that the tip surface 3 is as close to a mirror surface as possible. Further, in this case, the viewing angle is enlarged by diffusing the light emitted from the transparent plate 5 on the front surface side of the transparent plate 5, as in the case where a lenticular lens 8 (see FIG. 6) described later is provided. be able to.

The light absorption layer 6 is made of, for example, black matte ink, paint, film, sheet or tape, and its attachment is, for example, printing or painting using black matte ink or paint, Transfer can be performed by hot stamping or the like using a black matte transfer film or sheet, and further by adhesion or adhesion using a black matte film, sheet or tape. Alternatively, the light absorbing layer 6 can be provided by so-called flocking, in which a region where the light absorbing layer 6 is provided is coated with an adhesive and black single fibers are planted by electrostatic flocking. In particular, the light absorption layer 6 provided by using the Flocky process is preferable because deep black with very little reflection can be obtained.

The light absorbing layer 6 may be provided on the smooth surface of the transparent plate 5, but the surface portion of the transparent plate 5 on which the light absorbing layer 6 is provided is roughened by sandblasting or the like in advance. It may be provided on a rough surface.

From the tip surface 3 of the optical fiber 2 to the transparent plate 5
The distance t to the light absorption layer 6 provided on the front surface of the optical fiber is substantially the thickness of the transparent plate 5, but a deep black color is obtained when light is not emitted from the tip surface 3 of the optical fiber 2. Therefore, it is preferable that the following conditions are satisfied.

That is, when the distance between the tip surfaces 3 of the adjacent optical fibers 2 is P and the effective emission angle of the light emitted from the tip surface of the optical fiber 2 is θ, P / (20 tan
θ) ≦ t ≦ P / (2 tan θ) is preferable.

When the value of t becomes larger than P / (2 tan θ), the area where the light emitted from the tip surface 3 of the optical fiber 2 and the light emitted from the tip surface 3 of another adjacent optical fiber 2 overlap becomes wider. The area in which the light absorption layer 6 can be provided is narrowed, and it becomes difficult to obtain the sun visor-like action of the light absorption layer 6. In addition, the value of t is P / (20ta
If it is smaller than nθ), the tip surface 3 of the optical fiber 2 and the light absorption layer 6 are too close to each other, and it becomes difficult to obtain the sun visor-like action of the light absorption layer 6 again.

P is determined by the size of the screen, the number of optical fibers 2, and the arrangement state of the tip surface 3 of the optical fiber 2. For example, the size of the screen is 90 inches (diagonal length),
When the number of the optical fibers 2 is 170,000 and the arrangement of the tip surface 3 of the optical fibers 2 is the arrangement of FIG. 3A, P is about 4
mm.

A light absorbing layer 9 is provided on the rear surface of the transparent plate 5 except for the portion facing the front end surface 3 of the optical fiber 2. This light absorption layer 9 is not essential, but is preferably provided because it can prevent external light entering from the light emission surface 7 from being reflected by the display substrate 4. Instead of the light absorbing layer 9, the back surface of the transparent plate 5 may be roughened by sandblasting, or the light absorbing layer 9 may be further provided on the roughened surface.

FIG. 6 shows a second embodiment of the present invention in which a lenticular lens 8 is provided on the front surface of a transparent plate 5. The lenticular lens 8 is for diffusing the light emitted from the transparent plate 5 to widen the viewing angle, and at least the tip surface 3 of the optical fiber 2.
It is preferable to form it in the front surface region of the transparent plate 5 within the range of the effective emission angle θ of the light emitted from the transparent plate 5.

The lenticular lens 8 is provided on the bottom surface of the emitting recess 10 provided on the front surface side of the transparent plate 5.

The lenticular lens 8 does not necessarily have to be provided on the bottom surface of the emitting recess 10. However, if the lenticular lens 8 is provided on the bottom surface of the emitting recessed portion 10, it is possible to prevent external light from directly hitting the front surface of the lenticular lens 8 due to the light absorption layer 6, so that the front surface of the lenticular lens 8 is exposed. It is possible to prevent discoloration of the image color due to the reflection of light. Of course, even when the lenticular lens 8 is not provided, such an emission recess 10 is formed in at least the front surface region of the transparent plate 5 within the range of the effective emission angle θ of the light emitted from the tip surface 3 of the optical fiber 2. In addition, it is possible to make it difficult for external light to directly hit the bottom surface of the emitting recess 10 that serves as the light emitting surface 7 (see FIG. 1).

When the lenticular lens 8 is provided, the light emitted from the lenticular lens 8 is diffused and emitted at an angle exceeding the effective radiation angle θ, and the viewing angle is expanded. Therefore, in order not to block this diffused and emitted light, the lenticular lens 8 is provided on the bottom.
The side walls of the recess 10 for emission provided with are the effective radiation angle θ.
It is preferable to have an inclination of an angle of more than.

On the rear surface of the transparent plate 5, a light receiving concave portion 11 is formed at a position facing the front end surface of the optical fiber 2, and the front end of the optical fiber 2 slightly protruding from the front surface of the display substrate 4 is used for receiving the light. It has entered the recess 11.

The light receiving recess 11 is effective when the light absorbing layer 9 is provided on the rear surface of the transparent plate 5. That is, the transparent plate 5
If the light receiving recess 11 is formed by a drilling device or a cutting device after the light absorbing layer 9 is provided on the entire rear surface of the optical absorbing layer 9, the light absorbing layer 9 at a position facing the front end surface 3 of the optical fiber 2 is formed.
It is possible to save the trouble of preventing the formation of masks by masking. Also,
If the side wall of the light receiving recess 11 is inclined as shown in the drawing, when the transparent plate 5 is attached to the front surface of the display substrate 4,
This acts as a guide surface and guides the tip of the optical fiber 2 into the light-receiving recess 11, so that the alignment becomes easy.

The advantage of providing the light receiving concave portion 11 is not only when the light absorbing layer 9 is provided, but also when the transparent plate 5 is provided.
The same applies to the case where the rear surface is a rough surface and the case where the light absorption layer 9 is further provided on the rough surface.

FIG. 7 shows a third embodiment of the present invention, in which a light receiving convex portion 12 is provided on the rear surface of the transparent plate 5 at a position facing the front end surface of the optical fiber 2. Further, a light absorbing layer 9 is provided on a region of the rear surface of the transparent plate 5 excluding the light receiving convex portion 12.

With this arrangement, the incident light from the front surface 3 of the optical fiber 2 is prevented from entering the light absorption layer 6 on the front side of the transparent plate 5.
Not only can it be blocked by the light absorption layer 9 on the rear surface side of the transparent plate 5, but the contrast ratio can be further expanded.

In this embodiment, the light-receiving convex portion 12
A light emitting recess 11 similar to that described with reference to FIG. 6 is provided on the top surface of the optical disk to facilitate positioning when mounting the transparent plate 5 on the front surface of the display substrate 4.
Without the provision of the above, the above-mentioned double sun visor action can be obtained.

FIG. 8 shows a fourth embodiment of the present invention, which uses a transparent plate 5 which is a combination of a rear transparent plate 5a and a front transparent plate 5b.

The rear transparent plate 5a has a light receiving recess 1 on the rear surface side.
1. It has a joining convex portion 13 on the front side.

The front transparent plate 5b is provided with a recess 1 for joining on the rear surface side.
4 and the light absorption layer 9 is formed in the region on the rear surface side excluding the bonding recess 14. Further, an emission recess 10 having a lenticular lens 8 formed on the bottom is provided on the front side, and a light absorption layer 6 is formed on a region excluding the emission recess 10 on the front side.

The light receiving recess 11 of the rear transparent plate 5a is provided at a position facing the front end surface 3 of the optical fiber 2, and the joining protrusion 13, the joining recess 14 and the emitting recess 1 are provided.
The 0s are located in a line. Further, the joining convex portion 13 and the joining concave portion 14 are fitted to each other, and the rear transparent plate 5a and the front transparent plate 5b are integrally joined by a transparent adhesive or the like to form the transparent plate 5.

With this arrangement, the incident light from the front surface 3 of the optical fiber 2 is prevented from entering the light absorption layer 6 on the front side of the transparent plate 5.
Not only can it be blocked by the light absorption layer 9 located in the middle of the transparent plate 5, but the contrast ratio can be further expanded.

By the way, in the case of a large image display device of 90 inches or 100 inches or more, it is difficult to cover the entire screen with one transparent plate 5. Particularly in the case of the transparent plate 5 having the lenticular lens 8, a plurality of transparent plates 5
There is no choice but to use by horizontally joining.

In the case of an image display device of about 100 inches,
The number of normally used transparent plates 5 is about 4 to 9 if a large size plate obtained by the compression molding method is used. However, in the case of business card format that is easily obtained by general injection molding, 1000 to 2
000 sheets will be joined and used.

When a plurality of transparent plates 5 are joined and used, it is preferable that the joint is located at the light absorbing layer 6. In this way, the light emitted from the transparent plate 5 is not affected by the joints and the image is not broken, so that a high quality image can be obtained. Further, it is preferable that the positions of the screw holes and the like for attaching the transparent plate 5 to the display substrate 4 are also provided at the position of the light absorption layer 6 so as not to affect the image.

Next, an image display device actually manufactured by the present inventors will be described.

The core material of the optical fiber 2 is PMMA.
-Based resin, sheath material is polyvinylidene fluoride-based resin, 0.7
5 mm diameter ("Luminous DB-75" manufactured by Asahi Kasei Corporation)
0 ") was used.

The number of optical fibers 2 is 400 horizontal and 330 vertical.
The total number of steps is 132,000, and the focusing state of the rear end face 1 is the bale stacking state of FIG. 2 (a). As shown in FIG. 3A, the tip surfaces 3 of the optical fibers 2 are arranged in a horizontal series and in a staggered manner, and the distances P between adjacent tip surfaces are all 4.
It was set to 5 mm.

The size of the screen thus obtained is 1350 mm in length and 1800 mm in width, and is a large screen equivalent to 90 inches (diagonal length).

When focusing and arranging the rear end portion of the optical fiber 2, 100 optical fibers 2 are closely arranged in the lateral direction in advance, and an adhesive is applied to the rear end portion of the arranged optical fiber 2 to form a strip-shaped sheet. 110 pieces were laminated while adhering the rear end of this strip-shaped sheet with an adhesive to form one small block.

Twelve small blocks were prepared, and these four small blocks were arranged side by side in a row, and their rear end portions were bonded with an adhesive to form a lower block.

Next, another four small blocks are bonded in the same manner, the lower block is overlapped and the rear end is bonded to form a middle block, and the remaining four blocks are similarly bonded. By stacking and adhering on the middle block to form the upper block, 132,000 optical fibers 2 were arranged and the rear end was converged.

A plate of PMMA having a thickness of 8 mm was prepared as the display substrate 4, and this plate was perforated by an NC drilling machine according to the arrangement state of the tip surface 3 of the optical fiber 2. The hole diameter is 0.85 mm, the arrangement is as shown in FIG. 3A, the center-to-center distance between the holes is 4.5 mm, and the number of holes is 330 rows vertically and 400 holes horizontally.

The front end of the optical fiber 2 having the rear end converged and arrayed is inserted into each hole of the display substrate 4 obtained as described above, and the optical fiber 2 is protruded to the front side of the display substrate 4 after being bonded with an adhesive. The tip 2 was cut, and the cut tip surface 3 was polished.

The transparent plate 5 has the lenticular lens 8 formed on the front side, and is produced by hot press-molding a transparent PMMA extruded plate having a thickness of 3 mm and containing no coloring agent or light diffusing agent. did.

The lenticular lens 8 formed on the front side of the transparent plate 5 has a shape as shown in FIG. 9, and has a convex top surface 15 provided at the depressed position and convex total reflections on both sides. Surface 16 and refraction surface 17 continuous with the total reflection surface
And a straight surface 18 between the refracting surface 17 and the top surface 15.

In this lenticular lens 8, the total reflection surface 16 is a convex surface, and the light is reflected and condensed toward the opposing linear surface 18. Therefore, all the light reflected by the total reflection surface 16 is emitted from the linear surface 18. It Therefore, the light reflected by the total reflection surface 16 and incident on the linear surface 18 is transmitted without being reflected by the linear surface 18, and there is an advantage that there is no light loss and a bright screen is easily obtained.

The lens units of the lenticular lens 8 are connected, and the pitch between the unit lenses is 0.
It was set to 25 mm. The size of the transparent plate 5 on which the lenticular lens 8 is formed is 675 mm long and 900 m wide.
The thickness of the transparent plate 5 on which the lenticular lens was formed was 2.0 mm.

As another transparent plate 5, both sides are smooth, and the thickness of P is 2.0 mm, the length is 675 mm, and the width is 900 mm.
An MMA plate was prepared.

Both the transparent plate 5 on which the lenticular lens 8 is formed and the transparent plate 5 having both smooth surfaces are placed at the central position between the tip surfaces 3 of the optical fibers 2 when mounted on the front surface of the display substrate 4 described above. A black tape having a width of 1.8 mm is attached, and as shown in FIG. 4 (a), a striped light absorption layer 6 is formed on the front surface and a striped light absorption layer 6 is not formed. did. Further, after black coating is applied to the back surface to form the light absorption layer 9, when the light absorption layer 9 is attached to the front surface of the display substrate 4, counterboring is performed at a position facing the front end surface 3 of the optical fiber 2 to form the light receiving recess 11. The prepared one and the one in which the light absorption layer 9 and the light receiving recess 11 were not formed were prepared.

Table 1 shows the types of samples of the prepared transparent plate 5 and their states.

[0069]

[Table 1] Of the samples A to G shown in Table 1, a total of 4 sheets, one for each of four types, were attached to the front surface of the display substrate 4, and the images obtained were compared and evaluated.

In the comparative evaluation, a liquid crystal projector ("XV-HIZ" 0.2 kw manufactured by Sharp Corporation) was used as a light source, a moving image was projected from the laser disk onto the rear end face 1 of the optical fiber 2, and the screen was observed with the naked eye. I went with that.

The results are shown in Table 2.

[0072]

[Table 2]

[0073]

The present invention is as described above, and it is possible to obtain a clear image with a high contrast ratio.
In particular, the practicality of a large-sized image display device can be significantly improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a first embodiment of the present invention.

FIG. 2 is a diagram showing an arrangement state of a rear end surface of a focused optical fiber.

FIG. 3 is a diagram showing an arrangement state of a front end surface of an optical fiber.

FIG. 4 is a diagram showing an arrangement example of a light absorption layer provided on the front surface side of a transparent plate.

FIG. 5 is a graph showing the relationship between the luminance and the viewing angle obtained by the measurement for determining the effective emission angle.

FIG. 6 is a cross sectional view showing a second embodiment of the present invention.

FIG. 7 is a cross sectional view showing a third embodiment of the present invention.

FIG. 8 is a cross sectional view showing a fourth embodiment of the present invention.

FIG. 9 is an explanatory diagram of a lenticular lens.

[Explanation of symbols]

 1 rear end face 2 optical fiber 3 front end face 4 display substrate 5 transparent plate 5a rear transparent plate 5b front transparent plate 6 light absorbing layer 7 light emitting surface 8 lenticular lens 9 light absorbing layer 10 light emitting recess 11 light receiving recess 12 light receiving convex 13 Convex portion for joining 14 Recessed portion for joining

Claims (3)

[Claims] 1. The front surfaces of a large number of optical fibers, on which image light is incident from the focused rear end surface, are exposed at a front side of a display substrate with a space therebetween, and a transparent plate is provided on the front side of the display substrate. A light absorption layer is formed on the front side of the transparent plate, leaving the front area of the transparent plate within the range of the effective emission angle θ of the light emitted from the tip end of the optical fiber as the light emission surface. An image display device characterized by. 2. When the distance t between the tip surface of the optical fiber and the light absorption layer is P, the distance between the tip surfaces of adjacent optical fibers is P, and the effective emission angle of the light emitted from the tip surface of the optical fiber is θ. , P / (20 tan θ) ≦ t ≦ P /
2. It is in the range of (2 tan θ).
Image display device. 3. The image display device according to claim 1, wherein a lenticular lens is formed on the front surface side of the transparent plate in the range of the effective emission angle θ of the light emitted from the front end surface of the optical fiber.