KR20110096849A - Front light film having a paper texture and display employing the same - Google Patents

Abstract

Disclosed are a front light film and a display having the same.
The disclosed front light film includes a light guide plate, a rear outgoing light forming unit, and a paper texture forming unit, and allows light to be emitted to the rear side of the light guide plate and to feel a paper texture when a character or a picture is input to the screen.

Description

Front light film having a paper texture and a display having the same {Front light film having a paper texture and display employing the same}

It relates to a front light film having a paper texture and a display having the same.

Recently, a lot of media using touch panels have been developed. For example, there is an increasing demand for e-books that can be written using a touch panel. E-books are being developed in the form of reflective displays that use a backlight or external light such as sunlight or external illumination light. Books are usually viewed for a long time, and often do not switch screens, e-books often adopt a reflective display method that consumes less power. However, when using an external light source, there is a limitation that the display cannot be used in a dark environment. In order to compensate for this limitation, it may be provided with a front light unit installed in front of the panel as a lighting means of the reflective display.

Meanwhile, a writing input device using a touch panel is widely used in an e-book. When reading e-books, such as when reading a paper book, there are times when you want to underline the contents or take notes. Therefore, various handwriting input devices have been developed to satisfy the needs of these users. However, if the user can create a texture such as paper when writing a line or writing a memo using a writing input device, the user may be more satisfied.

It provides a front light film having a paper texture.

A display employing a front light film having a paper texture is provided.

Front light film having a paper texture according to an embodiment of the present invention, the light guide plate provided in front of the panel; And a protrusion pattern in which protrusions are disposed on a front surface of the light guide plate.

When the radius of the protrusion is R and the total reflection angle of the light guide plate is θc, the protrusion pattern has a height of R (1-cosθc) or less from the front surface of the light guide plate.

According to another aspect of the present invention, the protrusion may have a spherical shape or some shape of a spherical shape.

According to another aspect of the invention, the protruding pattern may be formed integrally with the light guide plate.

According to another aspect of the invention, the protruding pattern may comprise a bead.

According to another aspect of the present invention, an adhesive layer is further provided on the light guide plate, and the beads may be distributed to partially protrude from the adhesive layer.

Front light film according to another embodiment of the present invention, the light guide plate provided in front of the panel; A layer provided on the front surface of the light guide plate and having a refractive index smaller than that of the light guide plate; A light emitting array provided on a rear surface of the light guide plate to emit light toward the panel; And a protrusion pattern in which protrusions are disposed on a front surface of the layer.

According to another aspect of the invention, the light exit array may comprise a projecting array.

According to another aspect of the invention, the light exit array may have a cross section of any one of a curved shape, a triangle, a square, a trapezoidal shape.

According to another aspect of the invention, the layer may comprise a polymethylmethacrylate (PMMA) or an adhesive layer.

Front light film according to another embodiment of the present invention, the light guide plate provided in front of the panel; A diffuse reflection part provided on a front surface of the light guide plate to be spaced apart from each other; And a black cover layer provided on the surface of the diffuse reflector.

According to another aspect of the present invention, a layer may be provided on the front surface of the light guide plate, and a protruding pattern may be further provided on the front surface of the layer.

According to another aspect of the invention, the layer may have a refractive index smaller than the refractive index of the light guide plate.

A display according to an embodiment of the present invention, the panel for forming an image; A front light film provided in front of the panel; And a light source for irradiating light to the front light film, wherein the front light film includes:

A light guide plate provided in front of the panel, and a protrusion pattern having protrusions disposed on a front surface of the light guide plate, wherein the radius of the protrusion is R and the total reflection angle of the light guide plate is θ c. It has a height of (1-cosθc) or less.

According to another embodiment of the present invention, a display includes a panel for forming an image; A front light film provided in front of the panel; And a light source for irradiating light to the front light film, wherein the front light film includes:

A light guide plate provided in front of the panel; A layer provided on the front surface of the light guide plate and having a refractive index smaller than that of the light guide plate; A light emitting array provided on a rear surface of the light guide plate to emit light toward the panel; And a protrusion pattern in which protrusions are disposed on a front surface of the layer.

According to another embodiment of the present invention, a display includes a panel for forming an image; A front light film provided in front of the panel; And a light source for irradiating light to the front light film, wherein the front light film includes:

A light guide plate provided in front of the panel; A diffuse reflection part provided on a front surface of the light guide plate to be spaced apart from each other; And a black cover layer provided on the surface of the diffuse reflector.

1 schematically illustrates a display with a front light film according to an embodiment of the present invention.
FIG. 2A illustrates a change in the path of propagation of light when the height of the protrusion pattern of the front light film shown in FIG. 1 is changed.
FIG. 2B is an enlarged view of a protrusion of the front light film shown in FIG. 1.
3A to 3F illustrate a change in the light output pattern according to the height change of the protruding pattern of the front light film shown in FIG. 1.
4 illustrates a modification of the display shown in FIG. 1.
Figure 5 shows a display with a front light film according to another embodiment of the present invention.
FIG. 6 illustrates the light output pattern of the front light film shown in FIG. 5.
Figure 7 shows a display with a front light film according to another embodiment of the present invention.
FIG. 8 shows a modification of the display shown in FIG. 7.

Hereinafter, a front light film and a display having the same according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. The embodiments illustrated below are not intended to limit the scope of the present invention, but are provided to fully explain the present invention to those skilled in the art. In the drawings, like reference numerals refer to like elements, and the size of each element in the drawings may be exaggerated for clarity and convenience of description.

1 shows a display with a front light film 15 according to one embodiment of the invention. The display illustrated in FIG. 1 may include a panel 10 forming an image and a front light film 15 provided in front of the panel 10. The front light film 15 may include a light guide plate 20 and a protruding pattern 22 provided on the front surface of the light guide plate 20. It may include a light source 30 for irradiating light to at least one side of the light guide plate 20. The light source 30 may include a point light source or a line light source. For example, a light emitting diode (LED) may be used as the point light source, and a cold cathode fluorescent light (CCFL) may be employed as the linear light source. The light guide plate 20 may convert light from the light source 30 into a shape of surface light. The light source 30 may be selectively used when it is difficult to display an image by only external light.

The protruding patterns 22 are protrusions 22a arranged on the front surface 20a of the light guide plate 20 to form a paper texture and to receive light from the light source 30 from the rear surface 20b of the light guide plate 20. Can be output as Hereinafter, the front surface 20a of the light guide plate 20 is the surface in the direction of the viewer 40 viewing the display, and the rear surface 20b of the light guide plate 20 represents the surface in the direction in which the panel 10 is located. . The front of the panel 10 indicates the direction in which the viewer 40 looking at the display is located.

 The panel 10 may be a reflective panel that forms an image using external light or light from the light source 30, and may include, for example, an e-ink panel or an LCD panel for an e-book. have. When it is possible to display an image using only external light, power consumption may be reduced by not using the light source 30. In addition, a detection layer 5 may be provided at the rear of the panel 10 to detect a touch by an input means such as a fan. The detection layer 5 may detect a position touched by an input means and transmit the detected position to the panel 10, and the panel 10 may display a letter or a shape as it is touched. The detection layer 5 may be disposed between the panel 10 and the light guide plate 20 as well as the rear of the panel 10. Since the detection layer 5 is known in various ways such as an induction method, a resistive film method, and a reduced pressure method, a detailed description thereof will be omitted. Meanwhile, the light guide plate may be configured to serve as a touch panel such as a resistive film method and a pressure sensitive method.

The front light film 15 guides the light emitted from the light source 30 to be output toward the panel 10, and has a light exit pattern forming unit for having a rear light exit pattern suitable for the front light type, and writing on a screen. It may include a paper texture forming unit that makes the paper feel the texture when drawing or lining. In the display illustrated in FIG. 1, the protruding pattern 22 may form a backside light pattern and a paper texture. The protrusion 22a of the protruding pattern 22 may have a spherical shape or a part of a spherical shape, and the light output pattern may change according to the height of the protrusion 22a. 2A shows that the light output pattern may be different when the height h of the protrusions 21a, 21b, 21c changes to h1> h2> h3. The protruding pattern 22 may adjust the height h of the protruding portion 22a in order to implement a rear light exit pattern.

 2B is an enlarged view of the protrusion 22a protruding from the front surface 20a of the light guide plate 20. When there is no protruding pattern in the light guide plate 20, the light within the critical angle θc in the light guide plate 20 does not exit the light guide plate. However, the incident angle of light along the surface of the protrusion 22a may be out of the critical angle. When the incident angle of the light is outside the critical angle, the light is emitted outside the light guide plate. Here, when the angle θ between the normal line P of the incident surface I and the vertical center line C of the protrusion 22a has an angle equal to or less than the critical angle θc, the light emitted to the outside is the vertical center line ( Since light is emitted in a direction close to the front surface 20a of the light guide plate with a large angle with respect to C), substantially no light enters the viewer's eyes. On the other hand, when the angle θ between the normal line P of the incident surface I and the vertical center line C of the protrusion 22a is greater than the critical angle θc, the light emitted to the outside is directed upward of the light guide plate. Light is directed toward the viewer's eyes, which can reduce contrast. That is, when the angle θ between the normal line I and the vertical center line C of the incident surface is larger than the critical angle θc, the light emitted to the outside enters the viewer's eyes to decrease the contrast and improve the back light emission efficiency of the light guide plate. Can be reduced. Therefore, in order to increase the contrast and increase the rear light output efficiency of the light guide plate, the angle θ between the normal line I and the vertical center line C of the incident surface has an angle below the critical angle θc as follows. .

cosθ≥cosθc ...... (Equation 1)

Referring to FIG. 2B, since cos θ = (R−h) / R is established, Equation 1 may be expressed as follows.

h≤R (1-cosθc) ... (Equation 2)

Here, R represents the radius of the protrusion 22a, and θc represents the total reflection angle of the light guide plate 20. The height h of the protrusion 22a satisfies Equation 2 so that the light from the light source is emitted to the rear side of the light guide plate so as to be suitable for the front light type. In addition, since the protrusion pattern 22 is exposed to the outside, a paper texture may be felt when writing.

3A to 3F show the light output pattern coming out toward the viewer's eye and the light exit pattern coming out to the panel when the height h of the protrusion 22a is 7 μm, 10 μm, 20 μm, 30 μm, 50 μm, 70 μm, respectively. Will be shown. When h is 7 µm or 10 µm, a light exit pattern of a high angle range is displayed on the panel side. The protrusion 22a may have a height of 10 μm or less so that the front light film has a rear light exit pattern. The protrusion pattern 22 may provide a paper texture when inputting a letter or a picture as well as realizing a rear light output pattern by adjusting a height. In addition, the size and density of the protruding pattern 22 can be adjusted according to the degree of paper texture.

The protrusion 22a may be integrally formed with the light guide plate 20. For example, the light guide plate 20 and the protrusion pattern 22 may be integrally manufactured by a mold. Alternatively, the protrusion 22a may be formed of beads. For example, as illustrated in FIG. 4, an adhesive layer 24 may be provided on the entire surface of the light guide plate 20, and the beads 25 may be partially exposed on the adhesive layer 24. The adhesive layer 24 may have a refractive index equal to that of the light guide plate 20. The height of the bead 25 exposed to the outside of the adhesive layer 24 may be arranged to satisfy the equation (2).

The display illustrated in FIG. 5 may include a panel 50, a front light film 65 provided in front of the panel 50, and a light source 55 irradiating light to the front light film 65. Can be. The front light film 65 may include a light guide plate 60, a first layer 70 provided on the front surface 60a of the light guide plate 60, and a protruding pattern provided on the front surface of the first layer 70. 75). The first layer 70 may have a refractive index n2 smaller than the refractive index n1 of the light guide plate 60. When the refractive index of the first layer 70 is smaller than the refractive index of the light guide plate 60, light is guided to travel in the light guide plate 60 by the total reflection principle due to the difference in refractive index. For example, the light guide plate 60 may include polyethylene terephthalate (PET), and the rear light emitting layer 70 may include a polymethylmethacrylate (PMMA) or an adhesive layer. In FIG. 5, the touch detection layer is omitted.

The paper texture may be realized by providing the protrusion pattern 65 having the protrusions 65a arranged on the front surface of the first layer 70. Here, the protruding pattern 65 only needs to have a volume for paper texture, and there is no need to specifically limit the height. For example, the protrusion 65a may have a curved cross section. However, the shape of the protruding portion 65a is not limited thereto. The protrusion 65a may be formed of beads.

The light exit array 63 may be provided on the rear surface 60b of the light guide plate 60 to send light toward the panel 50. The light exit array 63 is provided to increase rear light exit efficiency and may be formed integrally with the light guide plate 60 or separately. The light exit array 63 may have a cross section of any one of a curved shape, a triangle, a square, and a trapezoidal shape. The light exit array 63 may include various patterns such as a dot pattern or a pillar pattern. Light emitted from the light source 55 may proceed in the light guide plate 60 by the first layer 70, and may be emitted toward the panel 50 by the light exit array 63.

FIG. 6 illustrates a light exit pattern coming out toward the viewer's eye and a light exit pattern coming out toward the panel in the front light film 65 shown in FIG. 5. The amount of light emitted toward the panel is greater than the amount of light emitted toward the viewer's eyes, and the emission angle of light emitted toward the panel is higher than that of the light emitted toward the viewer's eyes. The emission angle of the light is based on the front side (or back side) of the light guide plate.

The display illustrated in FIG. 7 includes a panel 100 forming an image, a front light film 105 provided in front of the panel 100, and a light source 115 irradiating light to the front light film 105. ) May be included. Since the panel 100 and the light source 115 have substantially the same configuration and function as the panel 10 and the light source 30 of the display illustrated in FIG. 1, detailed descriptions thereof will be omitted. The front light film 105 includes a light guide plate 110, a paper texture forming unit and a rear light exit pattern forming unit provided on the front surface 110a of the light guide plate 110. Diffusing reflectors 120 are provided on the front surface of the light guide plate 110 to be spaced apart from each other. The diffusion reflector 120 may include a dot pattern formed by a printing method. The diffuse reflector 120 may be used as a paper texture forming unit and a rear light exit pattern forming unit. When the light emitted from the light source 115 travels through the light guide plate 110, the light may be diffused from the diffuse reflector 120 and output toward the rear surface 110b of the light guide plate. In addition, the diffuse reflector 120 may protrude on the front surface of the light guide plate to implement paper texture.

Meanwhile, a black cover layer 123 may be provided on the surface of the diffuse reflector 120. The black cover layer 123 may prevent some of the light diffused from the diffuse reflection part in the front direction from being output to the front of the light guide plate. In addition, the paper texture may be increased by the black cover layer 123. The diffusion reflector 120 and the black cover layer 123 may have a curved shape, but the shape is not limited thereto.

FIG. 8 illustrates an example in which the second layer 130 is further provided on the display illustrated in FIG. 7. A protruding pattern 135 is provided on the entire surface of the second layer 130. Although it is possible to implement a paper texture with the diffuse reflector 120, the second layer 130 and the protruding pattern 135 are further provided to compensate for the adhesion of the diffuse reflector 120 and improve the paper texture. It can be further reinforced. The second layer 130 may have a refractive index smaller than that of the light guide plate 110. As a result, the light may be guided to propagate into the light guide plate 110. The second layer 130 may include a PMMA or an adhesive layer.

 The front light film according to the embodiment of the present invention includes a back exit light forming unit and a paper texture forming unit, and the back out light forming unit and the paper texture forming unit may be implemented by one means or two means, respectively.

The display according to the embodiment of the present invention may display an image by using external light or a light source by using a reflection type. In the case of using the external light, the external light is incident on the panel through the front light film, and the image is displayed by controlling the external light on-off and reflecting the pixel for each pixel in the panel. In the case of using the light irradiated from the light source, light from the light source is emitted toward the panel in the front light film, and the image formed in the panel is reflected by this light and emitted to the outside to display the image. The front light film allows the light from the light source to be emitted at a higher angle to the rear than the front of the front light film so as to be used to make an image, so that the front light film has a light output pattern suitable for the front light type. In addition, it is also possible to perform a function to feel the paper texture when inputting characters or pictures using the input device.

The above embodiments are merely exemplary, and various modifications and equivalent other embodiments are possible to those skilled in the art. Accordingly, the true scope of protection of the present invention should be determined by the technical idea of the invention described in the following claims.

5 ... touch detection layer, 10,50,100 ... panel
15,65,105 ... front light film, 20,60,110 ... light guide plate
22,75,135 ... extrusion pattern, 30,55,115 ... light source,
120 ... diffused reflector, 123 ... black cover layer

Claims (16)

A light guide plate provided in front of the panel;
And a protrusion pattern in which protrusions are disposed on a front surface of the light guide plate.
A front light film having a height of R (1-cosθc) or less from the front surface of the light guide plate when the radius of the protrusion is R and the total reflection angle of the light guide plate is θc. The method of claim 1,
The protrusion portion has a spherical or spherical front light film. The method of claim 1,
The protruding pattern is a front light film formed integrally with the light guide plate. The method of claim 1,
The protruding pattern comprises a front light film. The method of claim 4, wherein
An adhesive layer is further provided on the light guide plate, and the front light film is distributed such that the beads partially protrude from the adhesive layer. A light guide plate provided in front of the panel;
A layer provided on the front surface of the light guide plate and having a refractive index smaller than that of the light guide plate;
A light emitting array provided on a rear surface of the light guide plate to emit light toward the panel; And
And a protrusion pattern in which protrusions are disposed in front of the layer. The method of claim 6,
And the light exit array comprises a projecting array. The method of claim 7, wherein
The light exit array is a front light film having a cross section of any one of a curved, triangular, square, trapezoidal shape. The method of claim 6,
The layer is a front light film including polymethylmethacrylate (PMMA) or an adhesive layer. The method of claim 6,
The protruding pattern is a front light film including a bead A light guide plate provided in front of the panel;
A diffuse reflection part provided on a front surface of the light guide plate to be spaced apart from each other; And
And a black cover layer provided on a surface of the diffuse reflection part. 12. The method of claim 11,
The front light film is provided with a layer on the front of the light guide plate, the projection pattern is further provided on the front of the layer. The method of claim 12,
And the layer has a refractive index less than that of the light guide plate. The method of claim 13,
The front light film of the layer comprises a polymethylmethacrylate (PMMA) or an adhesive layer. A panel forming an image;
The front light film according to any one of claims 1 to 14; And
And a light source for irradiating light to the front light film. 16. The method of claim 15,
And said panel comprises an e-ink panel or an LCD panel.

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