KR101385041B1 - Backlight unit for autostereoscopic 3-dimension image display device - Google Patents

Abstract

According to an aspect of the present invention, there is provided a backlight for an autostereoscopic 3D display, comprising: a light guide plate having a first surface and a second surface opposite thereto, and configured to change a path of light incident from a light source at a side toward the first surface; A first prism film laminated on the first surface of the light guide plate; And a second prism film laminated on the first prism film, wherein the second prism film forms a variable prism pattern on an emission surface, and the variable prism pattern has a plurality of unit prisms arranged in a line. The first unit prism is different from the neighboring second unit prism and the left and right bottom angles, and when defining the left and right bottom angles of each unit prism constituting the variable prism pattern as α and β, respectively, the α and β fluctuate according to the following equation. It is characterized by.
[Formula 1]

Description

BACKLIGHT UNIT FOR AUTOSTEREOSCOPIC 3-DIMENSION IMAGE DISPLAY DEVICE}

The present invention relates to a backlight for an autostereoscopic three-dimensional display. More specifically, the present invention relates to a backlight for an autostereoscopic 3D display which does not require alignment by introducing a prism film having a variable prism pattern.

The three-dimensional display is a display device for displaying an image having a three-dimensional (depth) feeling to the user. As one of the next generation display technologies to replace the current flat panel display (FPD), three-dimensional display is receiving great attention. Current flat panel displays basically display image information only on a two-dimensional plane, that is, the display surface thereof, and thus have a limitation in that it is impossible to express three-dimensional images.

The stereoscopic image is made by the principle of stereo vision through the human eyes. The binocular parallax that appears because the eyes are about 65 mm apart is an important factor of the stereoscopic sense. The three-dimensional display using binocular disparity includes a spectroscopic method and an autostereoscopic method. There are polarizing glasses method and shutter glasses method in the glasses method, and there are fundamental constraints on wearing glasses. Recently, studies on the glasses-free method have been actively conducted. The non-glasses type includes a lenticular lens method, a parallax barrier method, a liquid crystal shutter method, and the like.

The lenticular method was already patented by H.E.Ives in 1932 for lenticular stereo but had not been activated for a long time due to lack of processing or material technology. Since then, the lenticular method has attracted attention as the precision processing technology, the plastics industry, and the photo / print technology have developed.

US Patent Nos. 7,417,798 and 7,528,893 disclose three-dimensional displays in which a lenticular lens and a prism pattern are combined. 1 is a conceptual diagram illustrating the operation principle of a three-dimensional display according to the prior art. Referring to FIG. 1, in the conventional autostereoscopic 3D display, a first light source 310a and a second light source 310b are positioned at both sides of the light guide plate 300, and a lenticular lens and a prism pattern are formed on the light guide plate 300. The combined 3D film 180 is positioned, and the liquid crystal panel 200 is positioned again above. The light emitted from the first light source 310a and the second light source 310b passes through the light guide plate 300 and the 3D film 180, and its path is changed and refracted, so that the image is displayed on the left eye E1 and the right eye E2, respectively. Will make

The three-dimensional display according to the prior art has a problem in that the lenticular lens and the prism pattern integrated film must be produced very precisely, and as the size of the display becomes larger, the manufacturing tolerance increases, making alignment difficult. In addition, there is a problem of a complicated structure and a poor resolution. One of the important performance parameters in autostereoscopic 3D displays is crosstalk between viewpoints. Crosstalk means that an unintentional viewpoint image is partially seen even when observed from a designated viewpoint position. This crosstalk acts as a major cause of impairing the stereoscopic sense of the observer. The three-dimensional display according to the prior art described above may be vulnerable to crosstalk problems. In addition, a moire phenomenon may occur due to interference between a lenticular lens having a very regular pattern in front of and behind the display panel, a prism pattern, and a regular pixel pattern of the display panel.

One object of the present invention is to provide a backlight for an autostereoscopic 3D display having a simple structure and a manufacturing method and requiring no alignment.

Another object of the present invention is to provide a backlight for an autostereoscopic three-dimensional display that is easy to large area and low cost.

Still another object of the present invention is to provide a backlight for an autostereoscopic 3D display that can prevent crosstalk and moiré phenomena and provide high quality images.

The technical objects to be achieved by the present invention are not limited to the above-mentioned technical problems, and other technical subjects which are not mentioned can be understood by those skilled in the art from the following description.

One aspect of the invention relates to a backlight for autostereoscopic three-dimensional displays. The backlight for an autostereoscopic 3D display includes a light guide plate having a first surface and a second surface opposite thereto, and configured to change a path of light incident from a light source at a side toward the first surface; A first prism film laminated on the first surface of the light guide plate; And a second prism film laminated on the first prism film, wherein the second prism film forms a variable prism pattern on an emission surface, and the variable prism pattern has a plurality of unit prisms arranged in a line. The first unit prism is different from the neighboring second unit prism and the left and right bottom angles, and when defining the left and right bottom angles of each unit prism constituting the variable prism pattern as α and β, respectively, the α and β fluctuate according to the following equation. It is characterized by:

[Formula 1]

In the above,

Where α is the bottom left angle of the unit prism, β is the right bottom angle of the unit prism, L is the viewing distance, W _eye is the distance between both eyes, n _c is the refractive index of the variable prism, and Θ _iL is variable when the left light source is turned on. The incident angle incident on the prism film, Θ _iR is the incident angle incident on the variable prism film when the right light source is turned on, x is the position away from the center unit prism)

In embodiments, the α value is characterized in that in the range of 20 ° to 75 °.

In an embodiment, the variable prism pattern is characterized in that each unit prism has the same pitch, and the height between the neighboring unit prism is different.

In an embodiment, the variable prism pattern is characterized in that each unit prism has the same height, and the pitch between neighboring unit prism is different.

In embodiments, the incident surface of the first prism film and the second prism film is characterized in that the pattern is not formed.

In embodiments, the light guide plate may have a prism pattern formed on a second surface thereof. The prism pattern on the second surface may have a pitch of 5 μm to 300 μm.

The first prism film is characterized in that the prism pattern is formed on the exit surface.

In embodiments, the first prism may have a vertex angle of 50 ° to 150 degrees.

In embodiments, the first prism has a pitch of 5 ㎛ to 300 ㎛ pitch.

In embodiments, left and right light sources are provided on both side surfaces of the light guide plate, respectively, when the left light source is turned on, the first and second prism films are sequentially directed to the left eye, and the first and second light sources are turned on. The prism film is sequentially directed to the right eye.

The backlight for the autostereoscopic 3D display of the present invention does not require alignment, and can easily align the lenticular film, the barrier film, and the like, and thus, the manufacturing method is simple and the large area can be easily increased. In addition, crosstalk can be prevented by the structure, arrangement, and barrier film of the prism, and the moiré phenomenon can be prevented. In addition, high resolution is possible and high quality images can be provided.

1 is a conceptual diagram illustrating the operation principle of a three-dimensional display according to the prior art.
2 is a schematic cross-sectional view showing a backlight for autostereoscopic 3D display according to an embodiment of the present invention.
3 is a schematic cross-sectional view showing a backlight for autostereoscopic 3D display according to another embodiment of the present invention.
4 is a schematic cross-sectional view showing a unit prism of a variable prism according to an embodiment of the present invention.
5 is a schematic cross-sectional view illustrating a variable prism pattern according to an embodiment of the present invention.
Figure 6 is a graph showing the α, β values for each position in Example 1.
Figure 7 shows the distribution of the emission angle for each position in Example 1.
8 compares the distribution of the exit angle for each position and the required angle in Example 1;
Figure 9 is a graph showing the α, β values for each position in Example 2.
FIG. 10 shows the distribution of emission angles according to positions in Example 2. FIG.
FIG. 11 compares the distribution of the exit angle for each position and the required angle in Example 2. FIG.
FIG. 12 is a graph showing α and β values according to positions in Example 3. FIG.
Figure 13 shows the distribution of the emission angle for each position in Example 3.
FIG. 14 compares the distribution of the exit angle for each position and the required angle in Example 3. FIG.

As used herein, the term "prism" refers to a triangular pattern in cross section, and the term "pitch" refers to the width of bone and bone in the prism.

2 is a schematic cross-sectional view showing a backlight for autostereoscopic 3D display according to an embodiment of the present invention. As shown, the backlight for autostereoscopic 3D display of the present invention has a structure in which the light guide plate 30, the first prism film 20, and the second prism film 10 are sequentially stacked. Both side surfaces of the light guide plate 30 are provided with left and right light sources 31a and 31b. The light source may be a light source such as a light emitting diode or a cold cathode fluorescent lamp (CCFL).

In the following description, the left eye, right eye, left light source and right light source are named left and right for convenience of description and may not necessarily coincide with the observer's left eye and right eye.

The light guide plate 30 has a first surface 30a and a second surface 30b, and the path of the light introduced from the light sources 31a and 31b on the side surface is changed toward the first surface 30a. Preferably, the light guide plate 30 may have a prism pattern formed on a second surface thereof, as shown in FIG. 3. As such, since the prism pattern is formed on the second surface, the light guide plate exit half-angle angle can be limited to focus on a desired position. In an embodiment, the prism pattern on the second surface may have a pitch of about 5 μm to about 500 μm. There is an advantage in that it can adjust the exit angle and uniformity of the light guide plate in the above range.

In addition, the prism height of the second surface (length from the valley of the prism to the vertex) may be 0.5㎛ to 45㎛. There is an advantage that can control the exit angle and uniformity in the above range.

The light guide plate 30 may or may not have a constant thickness t3. The thickness may have a thickness of about several mm, but the thickness of the light guide plate 30 is not limited. The light guide plate 30 may be manufactured by injection molding, extrusion, etc. of polymethyl methacrylate (PMMA), but the material and manufacturing method thereof are not limited.

Although not shown in the drawings, a reflector may be present under the light guide plate 30. The reflective plate may serve to reflect light emitted downward from the light guide plate 30 toward the light guide plate 30 again. In addition, antireflection coating (ARC) may be present on the first surface 30a of the light guide plate 30.

The first prism film 20 is stacked on the first surface 30a of the light guide plate 30.

The first prism film is characterized in that the prism pattern is formed on the exit surface. As the prism pattern is formed on the exit surface, the light guide plate exiting at an angle can be adjusted at an angle (20 ° to 50 degrees) suitable for use by the variable prism, and the light guide plate exit light distribution is further narrowed to increase final 3D performance. There are advantages to it. Hereinafter, when the prism pattern is formed on the exit surface, it is called a prismatic, and when the prism pattern is formed on the incident surface, it is called an inverted prism.

In an embodiment, the first prism film 20 may have a constant pitch P20. Preferably, the first prism has a pitch of 5 μm to 300 μm. There is an advantage to facilitate the workability in the above range and not to directly catch the pitch.

In addition, the first prism may have a vertex angle θ1 of 50 ° to 150 degrees. Easy to manufacture in the above range, there is an advantage that can be adjusted to a suitable angle to use the variable prism. The first prism film has a refractive index of 1.48 to 1.58. There is an advantage of facilitating film forming in the above range.

The second prism film 10 is stacked on the first prism film 20. In the present invention, the second prism film 10 forms a variable prism pattern on the emission surface. That is, each unit prism constituting the second prism film 10 has a shape and size different from that of the neighboring unit prism, and the distance from the screen, the distance between the eyes, the position of the unit prism, the size of the panel, and the lower prism It is determined by factors such as the exit angle of the and the refractive index of the variable prism portion.

4 is a cross-sectional view illustrating angles α and β in a unit prism of a variable prism according to an embodiment of the present invention.

3 is a schematic cross-sectional view showing a backlight for autostereoscopic 3D display according to another embodiment of the present invention.

As shown, when the left light source is turned on, the light is directed to the left eye sequentially through the first and second prism films, and when the right light source is turned on, it is directed to the right eye through the first and second prism films.

Preferably, the incident surface of the first prism film 20 and the second prism film 10 is characterized in that the pattern is not formed. In this case, it is possible to prevent surface scratches due to the inter-film interference, and there is an advantage of properly focusing the desired eye position.

The second prism film forms a variable prism pattern on an exit surface. In the variable prism pattern, a plurality of unit prisms are arranged in a line, and the first unit prism is different from the neighboring second unit prism at the left and right bottom angles. In an embodiment, when the left and right bottom angles of the unit prisms constituting the variable prism pattern are defined as α and β, respectively, the α and β may vary according to the following equation:

[Formula 1]

In the above,

Where α is the bottom left angle of the unit prism, β is the right bottom angle of the unit prism, L is the viewing distance, W _eye is the distance between both eyes, n _c is the refractive index of the variable prism, and Θ _iL is variable when the left light source is turned on. The incident angle incident on the prism film, Θ _iR is the incident angle incident on the variable prism film when the right light source is turned on, x is the position away from the center unit prism)

That is, as shown in Figure 3, when the vertical extension in the eye and the eye center, it is in contact with the central unit prism (CP) of the second prism. At this time, the vertex of the central unit prism is x is 0, and the distance away from the point where x is 0 is defined as "location away from the central unit prism". From the central unit prism, x has a negative value on the left side and a positive value on the right side.

In embodiments, the α value is characterized in that in the range of 20 ° to 75 °.

5 shows embodiments of a variable prism pattern according to the present invention. The pitch of the variable prism composed of a plurality of unit prisms on the light incident surface is called P1, P2, P3, P4, P5, ... Pn, and the lower left angles are respectively α1, α2, α3, α4. , α5, ..... αn, and the lower right angle is represented by β1, β2, β3, β4, β5 .... βn, and each height is h1, h2, h3, h4, h5, .... hn It is defined as. The height here means the height from the valley of the unit prism to the prism vertex.

In one embodiment, the variable prism pattern may have the same pitch for each unit prism, and in this case, heights between neighboring unit prisms may be different. That is, as shown in FIG. 5A, P1 = P2 = P3 = P4 = P5 = ,, ...... = Pn, and h1, h2, h3, h4, h5, ... .hn can be different.

In another embodiment, each of the unit prisms may have the same height, and in this case, pitches of neighboring unit prisms may be different from each other. That is, as shown in FIG. 5 (b), h1 = h2 = h3 = h4 = h5 =, ...... = hn, and P1, P2, P3, P4, P5, .. .... Pn may be different.

The α and β angles have different values depending on positions, which can be obtained from Equation 1 above.

3 is a schematic cross-sectional view showing a backlight for autostereoscopic 3D display according to another embodiment of the present invention.

As shown, when the left light source is turned on, the light is directed to the left eye sequentially through the first and second prism films, and when the right light source is turned on, it is directed to the right eye through the first and second prism films.

Preferably, in the embodiment, the incident surface of the first prism film 20 and the second prism film 10 is characterized in that the pattern is not formed. In this case, it is possible to prevent surface scratches due to the inter-film interference, and there is an advantage of properly focusing the desired eye position.

A liquid crystal panel (not shown) may exist above the second prism film 10. The liquid crystal panel is a panel in which liquid crystals, such as twisted nematic (TN) and optically compensated bend (OCB) liquid crystals, are injected between an upper substrate and a lower substrate, and are driven by thin film transistors (TFTs) and thin film diodes (TFDs). It may be an active matrix liquid crystal panel or a passive matrix liquid crystal panel. The upper substrate and the lower substrate may be made of a glass substrate or a plastic substrate.

The above-described autostereoscopic 3D display backlight may display a 3D image in a viewing area by time division driving. That is, the left view light and the right view light may be alternately passed through the liquid crystal panel, and the viewer may view the 3D image in synchronization with the image (image) of the liquid crystal panel.

 Hereinafter, the configuration and operation of the present invention through the preferred embodiment of the present invention will be described in more detail. It is to be understood, however, that the same is by way of illustration and example only and is not to be construed in a limiting sense.

Details that are not described herein will be omitted since those skilled in the art can sufficiently infer technically.

Example

Example  One

The simulation was performed under the conditions as shown in Table 1 below. Α and β values for each position are shown in FIG. 6.

Light guide plate prism 3D film material PMMA shape Reverse prism Α, β by position 6 Main
Exit angle +63 ^o : Left light source On
-63 ^o : Right light source On Refractive index 1.492 Refractive index 1.492 FWHM
(Half angle) ± 16 ^o pitch 0.03mm pitch 0.03mm - - Tip angle 30 ^o Focus position Left light source On → Left eye
Right light source On → Right eye

The emission angle distribution for each position is shown in FIG. 7. The result is when the left light source is turned on. When the right light source is turned on, the result will be left and right symmetrical. As shown in FIG. 7, the main peak is divided, and the result of shifting from the angle necessary for actual focus is shown from FIG. 8.

Example 2

The simulation was performed under the conditions as shown in Table 2 below. Α and β values for each position are shown in FIG. 9.

Light guide plate prism 3D film material PMMA shape Prism α, β 9 Main
Exit angle +70 ^o : Left light source On
-70 ^o : Right light source On Refractive index 1.492 Refractive index 1.492 FWHM
(Half angle) ± 9 ^o pitch 0.03mm pitch 0.03mm - - Tip angle 70 ^o Focus position Left light source On → Right eye
Right light source On → Left eye

The emission angle distribution for each position is shown in FIG. 10. The result is when the left light source is turned on. When the right light source is turned on, the result will be left and right symmetrical. As shown in FIG. 11, it can be seen that the exit angle for each position coincides well with the angle value necessary for focusing on the right eye.

Example 3

The simulation was performed under the conditions as shown in Table 3 below. Α and β values for each position are shown in FIG. 12.

Light guide plate prism 3D film material PMMA shape Prism α, β 12 Main
Exit angle +70 ^o : Left light source On
-70 ^o : Right light source On Refractive index 1.492 Refractive index 1.492 FWHM
(Half angle) ± 9 ^o pitch 0.03mm pitch 0.03mm - - Tip angle 70 ^o Focus position Left light source On → Left eye
Right light source On → Right eye

The emission angle distribution for each position is shown in FIG. 13. The result is when the left light source is turned on. When the right light source is turned on, the result will be left and right symmetrical. As shown in FIG. 14, it can be seen that the exit angle for each position coincides well with the angle value required for focusing on the left eye.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. It is therefore to be understood that the embodiments described above are in all respects illustrative and not restrictive.

10: second prism film 20: first prism film
30: light guide plate 31a, 31b: light source

Claims (11)

A light guide plate having a first surface and a second surface opposite thereto, the light guide plate configured to change a path of light incident from a light source on the side toward the first surface;
A first prism film laminated on the first surface of the light guide plate; And
A second prism film laminated on the first prism film;
The second prism film is formed to form a variable prism pattern on the exit surface,
In the variable prism pattern, a plurality of unit prisms are arranged in a line, and the first unit prism is different from the neighboring second unit prism and the left and right bottom angles,
When the left and right bottom angles of the unit prisms constituting the variable prism pattern are defined as α and β, respectively, α and β are changed according to Equation 1 below:
[Formula 1]

In the above,

Where α is the bottom left angle of the unit prism, β is the right bottom angle of the unit prism, L is the viewing distance, W _eye is the distance between both eyes, n _c is the refractive index of the variable prism, and Θ _iL is variable when the left light source is turned on. The incident angle incident on the prism film, Θ _iR is the incident angle incident on the variable prism film when the right light source is turned on, x is the position away from the center unit prism)

The backlight for autostereoscopic 3D display according to claim 1, wherein the? Varies in a range of 20 ° to 75 °.
The backlight for autostereoscopic 3D display according to claim 1, wherein each of the unit prisms has the same pitch and the heights of neighboring unit prisms are different from each other.
The backlight for autostereoscopic 3D display of claim 1, wherein each of the unit prisms has the same height, and pitches of adjacent unit prisms are different from each other.
The backlight for autostereoscopic 3D display according to claim 1, wherein the incident surfaces of the first prism film and the second prism film have no pattern.
The backlight of claim 1, wherein the light guide plate has a prism pattern formed on a second surface thereof.
7. The backlight of claim 6, wherein the prism pattern on the second surface has a pitch of 5 µm to 300 µm.
The backlight for autostereoscopic 3D display according to claim 1, wherein the first prism film has a prism pattern formed on an emission surface.
The backlight of claim 1, wherein the first prism film has a vertex angle of 50 ° to 150 °.
The backlight of claim 1, wherein the first prism film has a pitch of a prism pattern of about 5 μm to about 300 μm.
According to claim 1, Left and right light sources are provided on both sides of the light guide plate, respectively
When the left light source is turned on, the first and second prism films are sequentially directed to the left eye, and when the right light source is turned on, the first and second prism films are sequentially directed to the right eye. Dragon backlight.

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