KR102595280B1 - Light Coupler Controlling Viewing-Mode, Backlight Unit and Display Controlling Viewing-Mode Using the Same - Google Patents

Abstract

The present invention relates to an optical coupler for controlling a viewing mode capable of electronically controlling a privacy mode and a wide viewing angle mode, a backlight unit using the same, and a display for controlling a viewing mode using the same. The optical coupler for controlling the viewing mode of the present invention and a backlight unit using the same; The display can selectively implement a privacy mode and a wide viewing angle mode by selectively driving the first and second light sources and configuring a light entrance portion adjacent to the first and second light sources in a specific shape.

Description

Optical coupler for controlling viewing mode, backlight unit using same, and display for controlling viewing mode {Light Coupler Controlling Viewing-Mode, Backlight Unit and Display Controlling Viewing-Mode Using the Same}

The present invention relates to a display device, and particularly to a viewing mode control optical coupler capable of electronically controlling a privacy mode and a wide viewing angle mode, a backlight unit using the same, and a display for viewing mode control using the same.

Specific examples of flat panel displays include Liquid Crystal Display device (LCD), Organic Emitting Display Device, Plasma Display Panel device (PDP), and Quantum Dot Display Device. ), Field Emission Display device (FED), and Electrophoretic Display Device (EPD), etc., which commonly have a flat display panel that implements images as an essential component, A flat display panel has a structure in which a pair of transparent insulating substrates are bonded together with an inherent light-emitting, polarizing, or other optical material layer in between.

In particular, a light-receiving display device such as a liquid crystal display device has a liquid crystal panel that adjusts the light emission range by controlling the orientation direction of the liquid crystal, but has no light-emitting element itself. Therefore, a backlight unit is placed at the bottom to determine the intensity of light coming from the bottom, etc. Perform the display by adjusting .

A typical backlight unit places a light source on the side, positions a light guide plate on the side corresponding to the display panel, and performs a general function of transmitting light from the light source to the light guide plate and transmitting it to the display panel. In most cases, such a general backlight unit has a direction in which light is emitted from a display panel that requires surface light emission, and allows viewers in a specific range of the emitted light direction to view the display panel. This conventional backlight unit, in contrast to the privacy mode that allows certain viewers to view but prevents others from viewing, does not guarantee exposure of the screen to others, and has a wide viewing angle that allows multiple viewers to view without distinction. There are limitations to the mode, and once designed, the backlight unit has the disadvantage of not being able to adjust the light output range.

Therefore, in the conventional privacy mode, a transition from normal mode to privacy mode is attempted by selectively applying a privacy film.

Figure 1 is a diagram showing a privacy mode implemented using a conventional privacy film.

As shown in FIG. 1, the privacy mode using a conventional privacy film involves inserting a separate privacy film 10 on the screen of the display device 20 only in a specific privacy mode, and the mode can be changed by attaching and detaching the privacy film 10. distinguish between

However, this conventional privacy mode requires a manual process of attaching and detaching the privacy film 10 according to mode switching, so the user's action is required for mode switching. In addition, there is a problem that the outer design of the product is damaged due to the detachable structure.

In addition, although the privacy film 10 functions to prevent others from viewing, it is provided with multiple layers of plastic film, an optical coating layer, and a micro louver inside, so that it is itself placed on the upper part of the display device 20. It acts as a factor that reduces the transmittance when positioned, so viewers watching in privacy mode can perceive a decrease in luminance.

Additionally, the conventional privacy mode has a limitation in that the viewer must carry the privacy film 10 to view the video in privacy mode.

The present invention was made to solve the above-mentioned problems, and its purpose is to provide a backlight unit capable of electronically controlling privacy mode and wide viewing angle mode, and a display for controlling viewing mode using the same.

In order to achieve the above object, the optical coupler for viewing mode control of the present invention and the backlight unit and display using the same include selective driving of first and second light sources and a light incident portion adjacent to the first and second light sources in a specific shape. The configuration allows for selective implementation of privacy mode and wide viewing angle mode.

As an example, the optical coupler for viewing mode control of the present invention has a light emitting surface of a first width, a light emitting surface of a second width longer than the first width, and includes a first light source and a second light source alternately arranged in the same row. , a first side corresponding to the light emitting surface of the first width, and opposite to the first side, a second side of a third width greater than or equal to the second width, and having a second side of a third width greater than or equal to the second width. It includes a trapezoidal first light incident part and a second light incident part adjacent to second sides of the first light incident part corresponding to the first light source.

Here, the first light incident parts and the second light incident parts may be filled with a first medium having a first refractive index.

A space between the first light incident parts and the second light source in a plan view is defined as a third light incident part, and may be a triangle in the plan view.

The third light incident portion may be empty or may be filled with a medium having a second refractive index lower than the first refractive index.

First and second reflectors may be further provided above and below the first light incident part and the third light incident part.

Here, when the first light source is turned on, the light emitted through the light emitting surface of the first light source goes straight through the first light incident part and is transmitted to the second light incident part, and when the second light source is turned on, the light is emitted through the light emitting surface of the first light source. Light emitted through the light emitting surface of the second light source may pass through the third light incident part, be emitted to the first light incident part, and be transmitted to the second light incident part.

Also, the first light incident portion may have the same height as the trapezoid in plan.

The second light incident part has a rectangular shape in plan and may be at the same height as the first light incident part.

The second light incident portion is rectangular in plan, and its height may gradually decrease from the side adjacent to the first light incident portion to the opposite side.

In addition, the backlight unit of the present invention for achieving the same purpose each has a light emitting surface of a first width and a light emitting surface of a second width longer than the first width, and includes first and second light sources arranged alternately in the same row. It has a light source, a first side corresponding to a light emitting surface of the first width, and a second side opposite the first side that is equal to or larger than a third width obtained by adding the first and second widths, A light incident area including a trapezoidal first light incident unit and a second light incident unit in contact with second sides of the first light incident unit corresponding to the first light source, a light guide plate in contact with the second light incident unit and parallel to the light guide plate, and a light guide plate on the light guide plate. It may include an inverted prism sheet located and a reflector located below the light guide plate.

Here, the upper surface of the light guide plate faces the prism surface of the inverted prism sheet, the lower surface of the light guide plate has a plurality of straight light extraction patterns crossing the light guide plate, and one side of the light guide plate can be in contact with the light incident area. there is.

Also, the area between the first light incident parts may have a lower refractive index than the first light incident part.

In this case, the linear light extraction pattern is provided by removing a portion of the thickness of the lower surface of the light guide plate.

In addition, light is transmitted in parallel from the light incident area to the light guide plate, and the light guide plate scatters the light up and down through the linear light extraction pattern and transmits it to the inverted prism sheet to transmit it upward.

Meanwhile, when the first light source is turned on, the light emitted through the light emitting surface of the first light source in the light incident area passes straight through the first light incident part and is transmitted to the second light incident part, and the second light source When turned on, the light emitted through the light emitting surface of the second light emitting source in the light incident area may pass through the areas between the first light incident areas, radiate to the first light incident unit, and be transmitted to the second light incident unit. there is.

In addition, the first light incident part may be trapezoidal in plan and have the same height, and the second light incident part may be rectangular in plan and have the same height as the first light incident part, or the second light incident part may be rectangular in plan. , and the height may gradually decrease from the side in contact with the first light incident portion to the side opposite the light guide plate.

Meanwhile, the light incident area may be located above the light guide plate, and in this structure, reflectors may be further provided above and below the light incident area.

In addition, the light guide plate is in contact with the side of the light incident area, and the light guide plate has the same height as the light incident area on the side adjacent to the light incident area, and may gradually decrease in height toward the opposite side.

Meanwhile, a first medium layer having a lower refractive index than the light guide plate may be provided on the light guide plate, and a light extraction pattern in the form of a regular groove that transmits light upward in the direction of light may be further provided on the first medium layer.

In addition, the display for viewing mode control of the present invention may include the above-described backlight unit and a light-receiving image panel located on the backlight unit.

The optical coupler for viewing mode control of the present invention, the backlight unit using the same, and the display for controlling viewing mode have the following effects.

First, switching between privacy mode and wide viewing angle mode is possible electronically, so manual operation by the viewer is not required, providing convenience.

Second, a clean and stylish appearance of the product can be secured without a structure for attaching or detaching the privacy film.

Third, the switching function allows switching between privacy mode and wide viewing angle mode, and since there is no film covering the display panel in a specific mode, it is possible to implement that mode without reducing resolution.

Figure 1 is a diagram showing a privacy mode implemented using a conventional privacy film.
Figure 2 is a perspective view showing an optical coupler for viewing mode control according to a first embodiment of the present invention.
Figure 3 is a perspective view showing an optical coupler for viewing mode control according to a second embodiment of the present invention.
4A and 4B are diagrams showing a privacy mode and a wide viewing angle mode of the optical coupler for controlling the viewing mode of the present invention.
Figure 5 is a perspective view showing an optical coupler for viewing mode control according to a third embodiment of the present invention.
FIGS. 6A and 6B are diagrams showing a privacy mode and a wide viewing angle mode of the optical coupler for controlling the viewing mode of FIG. 5.
Figure 7 is a perspective view showing an optical coupler for controlling a viewing mode according to a fourth embodiment of the present invention.
8A to 8C are perspective views showing a tapered coupler in a region that is turned on in the privacy mode of the optical coupler for viewing mode control of the present invention, a wide viewing angle characteristic thereof, and a graph showing luminance characteristics by angle.
9A to 9C are perspective views showing a wedge-shaped coupler in a region that is turned on in the privacy mode of the optical coupler for viewing mode control of the present invention, a wide viewing angle characteristic thereof, and a graph showing luminance characteristics by angle.
10A to 10D are plan views of an experiment when the tapered optical coupler of the optical coupler for viewing mode control of the present invention is aligned with the opening of a light source, and photos taken from the front and left and right sides.
11A to 11D are plan views of an experiment when the tapered optical coupler of the optical coupler for viewing mode control of the present invention is partially aligned with the opening of the light source, and photos taken from the front and left and right sides.
12A to 12D are plan views of an experiment when the tapered optical coupler of the optical coupler for viewing mode control of the present invention does not match the opening of the light source, and photos taken from the front and left and right sides.
Figure 13 is a cross-sectional view showing a liquid crystal display device according to the first embodiment of the present invention.
FIG. 14 is a diagram showing the optical path of the light guide plate of FIG. 13 in privacy mode.
FIG. 15 is a diagram showing the optical path of the light guide plate of FIG. 13 in a wide viewing angle mode.
Figure 16 is a plan view showing a liquid crystal display device according to a second embodiment of the present invention.
FIG. 17 is a cross-sectional view taken along line I to I' of FIG. 16.
Figure 18 is a cross-sectional view showing the configuration of a backlight unit used in a liquid crystal display device according to a second embodiment of the present invention.
Figures 19a and 19b are graphs showing light intensity according to angle for each region during an experiment using Figure 18.
Figure 20 is a plan view showing a liquid crystal display device according to a third embodiment of the present invention.
Figure 21 is a cross-sectional view taken along line II to II' of Figure 20.
Figure 22 is a graph showing luminance characteristics by angle in privacy mode and wide viewing angle mode during an experiment using the liquid crystal display device of the present invention.

Hereinafter, preferred embodiments of the present invention will be described with reference to the attached drawings. Like reference numerals refer to substantially the same elements throughout the specification. In the following description, if it is determined that a detailed description of a known technology or configuration related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description will be omitted. Additionally, the component names used in the following description were selected in consideration of the ease of writing specifications and may be different from the component names of the actual product.

Figure 2 is a perspective view showing an optical coupler for viewing mode control according to a first embodiment of the present invention.

As shown in FIG. 2, the optical coupler for viewing mode control according to the first embodiment of the present invention has a light emitting surface with a first width (w1) and a light emitting surface with a second width (w2) that is longer than the first width, A first light source 110 and a second light source 120 arranged alternately in the same row, a first side corresponding to the light emitting surface of the first width w1, and opposite to the first side, the second light source 110 It has a second side of a third width greater than or equal to the width, and includes a first light incident portion 210a that is trapezoidal in plan and a second light incident portion 210b in contact with the second sides of the first light incident portion corresponding to the first light source. do.

Here, the third width may be equivalent to the second width, may be equivalent to the width obtained by adding the first and second widths, or may be larger than the width obtained by adding the first and second widths. When the third width is larger than the sum of the first and second widths, in addition to the first and second widths (w1, w2), which are the widths of the light emitting surfaces of the first and second light sources 110 and 120, This includes the gap between the first and second light sources 110 and 120, and in this case, the second sides of the first light incident portions 210a are in contact with each other.

In the optical coupler for viewing mode control according to the first embodiment of the present invention, the space between the first light incident parts 210a and the second light source 120 is empty. Therefore, the empty space corresponds to the refractive index of air, that is, 1, and the first and second light incident parts 210a and 210b are filled with a medium greater than the refractive index of air, and the first and second light incident parts 210a , 210b) is preferably integrated and made of the same material for the continuous propagation of light. And, the area including the first and second light incident areas 210a and 210b is referred to as the horizontal light incident area 210.

The area between the first light incident parts 210a and the second light source 120 in a plan view is defined as a third light incident part 300, and is triangular in plan or has the shape of the first light incident parts 210a. It may be a trapezoid of the same shape as . Additionally, the height of the first light incident portion 210a is the same. Note that, in the case of the optical coupler for viewing mode control according to the first embodiment of the present invention, the first light incident part 210a and the third light incident part 300 may have the same shape, and in this case, the first light incident part ( The second side of 210a) will have a length corresponding to the second width w2, and the short side of the trapezoid of the third light incident unit 300 is located between the second sides of the first light incident unit 210a. Accordingly, in terms of actual structure, the third light incident unit 300 is a trapezoid-shaped empty space in which the first and second sides of the first light incident unit 210a, which has a medium with a higher refractive index than air, are flipped up and down on a plane. .

Here, the first light incident parts 210a maintain a uniform height from the first side to the second side, and may have the same height as the height of the first light source 210 to reduce light loss. Three-dimensionally, each first light incident portion 210a is a hexahedron, the upper and lower surfaces of which are long trapezoids, and the remaining sides all have a rectangular shape, and the first side of the trapezoid corresponds to the first width and is opposite to this. The second surface is at least equal to or larger than the second width of the light emitting surface of the second light source 120. Additionally, the rectangles on the sides all have the same height, and a total of four rectangles are located on the sides. Also, the plurality of first light incident portions 210a have the same height. In this case, the light travels in the horizontal direction.

In addition, the first light incident part 210a and the third light incident part 300 have a width that is the sum of the first and second widths (w1, w2) of the first and second light sources 110 and 120. Forming it to be longer (making the length in the direction of light propagation longer) will be more effective for internal light guiding.

The first light incident parts 210a and the second light incident parts 210b are filled with a first medium having a first refractive index. That is, the first light incident parts 210a and the second light incident parts 210b are formed of a medium having at least the same refractive index. The same material as the first light incident portions 210a and the second light incident portion 210b may be used, or a different material but with the same refractive index may be used. In this case, in the privacy mode, light traveling through a limited area in the first light incident parts 210a passes through the second light incident part 210b with the width defined in the first light incident parts 210a, and has a wide viewing angle. In this mode, the light emitted from the third light incident unit 300 travels through the entire area including the first light incident unit 210a and the third light incident unit 300, and in a diverged state, the light enters the second light incident unit 210b. ) passes through. Additionally, the first and second light incident portions 210a and 210b may be of the same height.

Also, it will be optically advantageous for the first light source 110 and the second light source 120 to be in contact with the first and third light incident parts 210a and 300. Meanwhile, the third light incident portion 300 is an empty space, so it will not be difficult to bring the second light source 120 into contact with the third area 300, but the first light source 110 and the first mouth When coming into contact with the light source 210a, a material that does not yellow even when the light source is driven for a long period of time can be selected so that the first light incident part 210a on the surface that the light source touches does not deteriorate. Alternatively, the first light source 110 may be spaced apart from the first light incident part 210a by a predetermined distance, but the separation distance is such that the light from the first light source 110 is spaced at a certain width within the first light incident part 210a. It is determined at a level that does not interfere with guiding limited parallel light. In some cases, the first light source 110 may be attached to the first light incident portion 210a through an adhesive layer (not shown).

Meanwhile, in order to indicate the positions of the first and second light sources 110 and 120, the PCB (Printed Circuit Board) for driving the light source is omitted from the illustration, but the first and second light sources 110 and 120 are optionally turned on. For /off driving, a light source driving PCB may be provided on the bottom of the first and second light sources 110 and 120 or on the side that does not correspond to the first light incident parts 210a.

The optical coupler for viewing mode control according to the first embodiment of the present invention described above is implemented in a privacy mode when guiding parallel light limited to only the first light incident portion 210a, and the first and third When both light incident parts 210a and 300 are used for light guiding, they are implemented in light emission mode.

Figure 3 is a perspective view showing an optical coupler for viewing mode control according to a second embodiment of the present invention.

As shown in FIG. 3, the optical coupler for viewing mode control according to the second embodiment of the present invention includes the third light incident part 310 corresponding to the empty space in the first embodiment as the first and second light incident parts 210a and 210b. It is filled with a material with a low refractive index. That is, the first and second light incident parts 210a and 210b are filled with a material having a refractive index of n1, and the third light incident part 310 is filled with a material having a lower refractive index of n2 (<n1).

Here, since the same reference numerals as in the first embodiment have the same function, description thereof will be omitted.

Figures 4a and 4b are diagrams showing the privacy mode and wide viewing angle mode of the optical coupler for viewing mode control of the present invention.

As shown in FIG. 4A, the optical couplers for viewing mode control in the first and second embodiments described above are turned on by applying a first voltage V1 to the first light sources 110 in common, and the second voltage V1 is applied to the first light sources 110. When the light source 120 is turned off, light is transmitted from the first light source 110 to the first light incident part 210a that is in contact with or adjacent to the light emitting surface of the first light source 110, and the first light source 110 with a high refractive index Within the light incident part 210a, the light is totally reflected and travels, and the light passing through the first light incident part 210a is collimated and emitted from the second light incident part 210b in a straight-line form. .

In this case, the area between the first light incident parts 210a is empty or filled with a low refractive index material with a lower refractive index than the first light incident parts 210a, and is transmitted primarily through the first light source 110. , the light entering the first light incident parts 210a does not escape to the third light incident parts 300 or 310, and total internal reflection can be maintained.

In addition, in the first light incident parts 210a, light is transmitted as parallel light only at the divergence angle of the first light source 110, and therefore, the light substantially reaching the second light incident part 210b is the first light incident part 210b. 1 The width is limited to a portion of the second side of the light incident portion 210a, and as a result, parallel light is not transmitted throughout the entire area of the second light incident portion 210b, but is transmitted only to a portion of the width ( semi-collimation). This is because it is difficult to transmit light from a high refractive index medium to a low refractive index medium, and when the divergence angle of the first light source 110 is limited, even if it is totally reflected within the first light incident portion 210a, the emission area is limited. It's about using the enemy. Through this, privacy mode is implemented.

As shown in FIG. 4B, when the first light sources 110 are turned off and the second light sources 120 are turned on by common application of a second voltage V2, the light passing through the second light sources 120 proceeds along the third light incident portion 300 or 310 and has the characteristic of diverging at the same time. Accordingly, the light travels while diverging through the third light incident unit 300 or 310 and the first light incident unit 210a located in the same plane, and the light maintains divergence and is transmitted to the second light incident unit 210b. Through this, a wide viewing angle mode is implemented.

Figure 5 is a perspective view showing an optical coupler for viewing mode control according to a third embodiment of the present invention, and Figures 6a and 6b are diagrams showing the privacy mode and wide viewing angle mode of the optical coupler for controlling viewing mode of Figure 5.

Meanwhile, in the above-described first embodiment, in order to prevent light from escaping above or below the first to third light incident portions 210a, 210b, and 300, the third embodiment of the present invention is at least as shown in FIG. 5. , shows an example in which reflectors 410a and 410b are further provided above and below the first and third light incident parts 210a and 300, respectively.

Here, only the surfaces of the reflectors 410a and 410b that contact the first and third light incident portions 210a and 300 may be treated to be reflective, or the material itself may be made of a reflective metal, so that the first and third light incident portions (210a, 300) may be treated to be reflective. Light leakage in 210a, 300) can be prevented.

In particular, the reflectors 410a and 410b or the sheet can prevent random divergence of light in the vertical direction when the second light sources 120 are selectively turned on, as shown in FIG. 6B, and the upper and lower reflectors 410a and 410b It is possible to help the planar progress of light within the first and third light incident parts 210b, 300, or 310 by reflecting or guiding the progress of light therebetween.

Meanwhile, the reflectors 410a and 410b or the sheet may operate in the same manner as the first and second embodiments described above when selectively turning on the first light sources 110 as shown in FIG. 6A, and may operate in the same manner as the first and second embodiments of the divergent light. By helping internal light progress, light transmission efficiency is relatively higher than that of the first and second embodiments.

The light coupler described in the present invention is one that horizontally propagates light from a predetermined light source and transmits it to the light guide plate. A privacy mode and a wide viewing angle mode can be distinguished depending on the propagation width of the light.

As shown in FIG. 6A, when the first light sources 110 are commonly turned on with the first voltage V1 and the second light sources 120 are commonly turned off, the light emitting surface of the first light source 110 is in contact with the first light source 110. Alternatively, light is transmitted from the first light source 110 to the adjacent first light incident part 210a, and within the first light incident part 210a of high refractive index, the light is totally reflected and proceeds, and this first light incident part 210a The light that has passed through is collimated and is emitted to the second light incident portion 210b in a straight line.

In this case, the area between the first light incident parts 210a is empty with a lower refractive index than the first light incident parts 210a, and primarily passes through the first light source 110 to the first light incident parts 210a. The light entering through (210a) does not escape to the third light incident unit 300, maintains total internal reflection, and transmits parallel light of a limited width to the second light incident unit 210b.

In addition, as shown in FIG. 6B, when the first light sources 110 are commonly turned off and the second light sources 120 are commonly turned on by applying the second voltage V2, the second light sources 120 The light that has passed through proceeds along the third light incident portion 300 and has the characteristic of being diverged at the same time. Accordingly, the light travels while diverging through the third light incident unit 300 and the first light incident unit 210a located in the same plane, and the light maintains divergence and is transmitted to the second light incident unit 210b. Through this, a wide viewing angle mode is implemented. In this case, the divergent light is emitted by the reflectors 410a and 410b located above and below the third light incident unit 300 and the first light incident unit 210a, and is transmitted to the first light incident unit 210a between the reflectors 410a and 410b. ) is induced to proceed horizontally within the thickness.

Figure 7 is a perspective view showing an optical coupler for controlling a viewing mode according to a fourth embodiment of the present invention.

Meanwhile, as shown in FIG. 7, the optical coupler for viewing mode control according to the fourth embodiment of the present invention replaces the empty third light incident part 310 with the first light incident part 210a, compared to the above-described third embodiment. It is filled with a medium with a refractive index (n2) lower than ). In addition, compared to the second embodiment, first and second reflectors 410a and 410b are further provided above and below, or an insulating sheet with a low refractive index is further provided.

The top and bottom of the first and third light incident parts 210a and 310 may be formed by commonly disposing a reflector or an insulating sheet with a low refractive index (n3) (n3<n2<n1). Through this, the reflectors 410a and 410b can maintain horizontal progress between the low refractive index insulating sheets without external loss of light.

On the other hand, when replacing the reflectors 410a and 410b with low refractive index insulating sheets, it is generally difficult to find a material with a refractive index smaller than that of air, so as in the fourth embodiment, the first light incident part 210a and the second light incident part 210a (210b) is filled with a material with a second refractive index (n2<n1) smaller than the first refractive index, and the third light incident portion 310 is filled with a material with a second refractive index (n2<n1), as shown in FIG. 3, as shown in FIG. An optical coupler for switching viewing modes can be provided by placing an insulating sheet with a third refractive index (n3) (n3<n2<n1) smaller than the first and second refractive indexes at the positions (410a, 410b).

Hereinafter, the optical characteristics of the optical coupler for viewing mode control according to the present invention will be examined through experiments when applied to a backlight unit.

Figures 8a to 8c are a perspective view showing a tapered coupler in a region that is turned on during the privacy mode of the optical coupler for viewing mode control of the present invention, a wide viewing angle characteristic thereof, and a graph showing luminance characteristics by angle.

FIG. 8A schematically shows a case in which only the first light source 110 is selectively turned on in the optical coupler for viewing mode control according to the above-described first to fourth embodiments, and shows the first light incident portion 210a and the optical coupler integrated therewith. Only the second light incident portion 210b is shown located on the light guide plate side. Since there is no light transmission from the other second light source 120 or to the third light incident unit, this is a rough perspective view showing only the elements used for light propagation. Representatively, only one first light incident portion 210a is shown, but this shape is repeatedly located on one side of the light guide plate.

In this experiment, the light guide plate had a thickness of 1 mm, and a material with a refractive index of 1.5 was used. Additionally, the size of the first light source was set to 1x1 mm, the refractive index of the first light incident portion 210a was 1.67, and its thickness was set to 1 mm. The total bezel area is equivalent to 10mm.

In this structure, as shown in Figures 8b and 8c, the light traveling through the light guide plate has a peak at 0° with respect to the center of the light source and has a full width at half maximum (FWHM) of 18°, from -9° to +9° from the center of the light source. has a luminance of 50% or more of the peak luminance. That is, when only the first light source is driven, parallel light propagates selectively only in some areas of the first light incident portion 210a, and light is guided in the light guide plate to follow this light propagation characteristic, so that the light is emitted in the form of semi-collimation, Therefore, it is possible to implement privacy mode.

9A to 9C are perspective views showing a wedge-shaped coupler in a region that is turned on in the privacy mode of the viewing mode control optical coupler of the present invention, a wide viewing angle characteristic thereof, and a graph showing luminance characteristics by angle.

9A, in the optical coupler for viewing mode control according to the above-described first to fourth embodiments, a case in which only the second light source 120 is selectively turned on is schematically shown, and the second light source 120 is in contact with the second light source 120. Since the first light incident part 210a between the third light incident part 300 or 310 is commonly used as a light guiding member, it is shown as integrated with the light guide plate.

In this case, as shown in FIGS. 9B and 9C, there are two peaks at an angle of ±14° from the center of the second light source, and their half width angles are each 13°, relatively compared to the results of FIGS. 8A to 8C. , the range of the emission angle from the optical coupler to the light guide plate is increased, making it possible to implement a wide viewing angle.

In the experiments of FIGS. 9A to 9C, the light guide plate had a thickness of 1 mm, and a material with a refractive index of 1.5 was used. Additionally, the size of the second light source was set to 1x1 mm, the refractive index of the first light incident portion 210a was 1.67, and its thickness was set to 1 mm. The total bezel area is equivalent to 10mm. In this case, it was confirmed that the emission angle increases even when the size of the second light source is set to the same size as the first light source. Therefore, as in the first to fourth embodiments of the present invention, when the length of the second light source is increased, the emitted emission increases. The angle of light can also be expected to increase.

Hereinafter, we will examine through experiments whether the first light incident part and the third light incident part correspond to the light source and the light guiding form.

10A to 10D are plan views of an experiment when the tapered optical coupler (first light incident part) of the optical coupler for viewing mode control of the present invention is aligned with the opening of the light source, and photos taken from the front and left and right sides.

For example, when the first light incident portion of the above-described embodiments is aligned with the center of the light source, as shown in FIG. 10C, light progresses significantly in a certain angle range from the center of the light source, and as shown in FIGS. 10B and 10D, the light source It can be seen that almost no light progresses in areas located on the left and right sides of .

In this experiment, the opening of the light source used a mask with an opening for a width limited to a portion of the width of the light source. In reality, the mask is not used in the optical coupler, but was used to examine the directionality and concentration of light guiding. This is the structure chosen.

11A to 11D are plan views of an experiment when the tapered optical coupler (first light incident part) of the optical coupler for viewing mode control of the present invention is partially aligned with the opening of the light source, and photos taken from the front and left and right sides.

As shown in Figure 11a, if the first light incident part is positioned to partially overlap the opening of the light source, it can be confirmed that a certain portion of light is guided in the center and on the left and right sides of the light source, respectively, as shown in Figures 11b to 11d. However, in this case, it can be seen that the luminance is not strong even in a specific direction, and although there is guiding of light in multiple directions, the efficiency is low.

Figures 12a to 12d are plan views of an experiment when the tapered optical coupler (first light incident part) of the optical coupler for viewing mode control of the present invention is not aligned with the opening of the light source, and photos taken from the front and left and right sides.

As shown in Figure 12a, the optical coupler for viewing mode control of the present invention corresponds between the first light incident parts and the opening to the center of the light source, thereby significantly lowering the intensity of the light emitted from the center of the light source and increasing the intensity of the light emitted to the left and right. It has been increased.

Through these experiments, it was confirmed that the guiding direction of light can be adjusted to the degree of correspondence with the center of the light source.

Hereinafter, a display device to which the optical coupler for viewing mode control of the present invention described above is applied will be described. The display device described later is a liquid crystal display device, which is a type of light-receiving display device, but if it is a light-receiving display device, it may also be applied to other types of display panels. In addition, the above-described optical coupler is used as a light receiving part of a light-receiving display device and is provided in a form corresponding to one side of the light guide plate, and the above-described embodiment can be selectively applied.

FIG. 13 is a cross-sectional view showing a liquid crystal display device according to the first embodiment of the present invention, FIG. 15 is a view showing the optical path of the privacy mode of the light guide plate of FIG. 13, and FIG. 15 is a view showing the optical path of the light guide plate of FIG. 13 in the wide viewing angle mode. This is a diagram showing the optical path.

13 to 15, the liquid crystal display device according to the first embodiment of the present invention, like the first to fourth embodiments described above, has a light emitting surface of a first width and a second width longer than the first width, respectively. A first light source 110 and a second light source 120 having a light emitting surface of a wide width and arranged alternately in the same row, a first side corresponding to the light emitting surface of the first width, and opposite to the first side. , a second light incident portion having a second side of a third width greater than or equal to the second width, and contacting the first light incident portion 210a of a trapezoid in plan and the second sides of the first light incident portion corresponding to the first light source ( It includes a light incident area including 210b), a light guide plate 600 parallel to and in contact with the second light incident portion, an inverted prism sheet 550 located on the light guide plate, and a reflector plate 700 located below the light guide plate.

In the area between the first light incident parts 210a, an empty third light incident part 300 is defined, as in the first and third embodiments described above, or as in the second and fourth embodiments, the third light incident part 300 is defined. A third light incident portion 310 defined by being filled with a medium having a lower refractive index than the first light incident portions 210a may be included.

Meanwhile, even if the light passing through the first light incident part 210a, the second light incident part 210b, and the third light incident part 300 or 310 travels horizontally, the light may escape from the bottom or outside of the light guide plate 600. In order to guide this upward, a reflector 700 may be further provided on the lower side of the light guide plate 600, and the lower surface of the light guide plate 600 has a light extraction pattern 610 in the form of a regular groove. is further provided, so that the light exiting the lower side of the light guide plate 600 can be deflected and transmitted to the upper side.

Meanwhile, in the enlarged view of the light incident area shown on the lower right side of FIG. 13, the third light incident area 310 is shown to be filled, but this is not limited to this and can also be applied when it is empty. In addition, by extension, it can also be applied when reflectors (see 410a and 410b in FIGS. 5 and 7) are provided above and below the first and third light incident portions 210a, 300, or 310. That is, the liquid crystal display device according to the first embodiment of the present invention can be applied to any embodiment of the optical coupler for viewing mode control according to the first to fourth embodiments described above.

In addition, the inverted prism sheet 550 is provided with an inverted prism pattern 550 on the lower side, allowing light coming from the lower side in a diagonal direction to be guided toward the upper direction.

Here, the image panel 500 is positioned on the optical member such as the inverted prism sheet 550 at a certain interval. Although not shown, a bezel may be included to support and be spaced apart from lower components such as the image panel 500 and the inverted prism sheet 500. In addition, components other than the image panel 500 and the bezel are called backlight units in the sense that they transmit light to the light-receiving image panel 500.

Here, the image panel 500, like a liquid crystal panel, cannot emit light on its own, and receives light from the bottom, top, or side and uses it for display.

In addition to the optical couplers of the first to fourth embodiments described above, the backlight unit of the present invention includes a light guide plate 600 formed on the side, reverse pliss sheets 550 above and below the light guide plate, and a reflector 700. The image panel 500 allows different types of light transmission depending on the privacy mode and wide viewing angle mode. That is, through a switchable optical coupler, in privacy mode, semi-collimated light is transmitted upward through the optical coupler, enabling display only in a certain area, and in wide viewing angle mode, divergent light is transmitted through the optical coupler. It is possible to implement a wide viewing angle mode by emitting light through the light guide plate 600 and the inverted prism sheet 550 above it to diverge the light emitted to the image panel 500.

Meanwhile, as shown in FIGS. 14 and 15, the groove-shaped light extraction pattern 610 provided in the light guide plate 600 of the present invention is elongated in a straight line and transmits horizontally transmitted light by collimating it upward. .

Figure 14 shows the privacy mode, in which the semi-collimated and horizontally transmitted light is transmitted upward through each light extraction pattern 610 with only the direction of parallel light changed, and Figure 15 shows the wide viewing angle mode, in this case. The light is transmitted by diverging toward the light guide plate 600, and the transmitted light meets the light extraction pattern 610 and maintains its divergence upward to emit light.

Here, the upper surface of the light guide plate 600 faces the prism surface of the inverted prism sheet 550, and the lower surface of the light guide plate 600 is provided with a plurality of straight light extraction patterns crossing the light guide plate, and the light guide plate ( One side of 600) may be in contact with the light incident area.

In this case, the linear light extraction pattern 610 is provided by removing a portion of the thickness of the lower surface of the light guide plate 600.

In addition, light is transmitted in parallel from the light incident area to the light guide plate 600, and the light guide plate 600 scatters the light up and down through the linear light extraction pattern 610 to form the inverted prism sheet 550. It can be transmitted to the upper side.

Meanwhile, like the liquid crystal display device of the first embodiment described above, the first and second light incident portions 210a and 210b may have the same height, but the height of the second light incident portion on the side that does not correspond to the light source may be adjusted. will be. In this case, when the first light incident part 210a and the second light incident part 210b are the same, both the privacy mode and the wide viewing angle mode in the light incident area are horizontal in the direction of light travel.

This is explained in the second embodiment of the present invention.

FIG. 16 is a plan view showing a liquid crystal display device according to a second embodiment of the present invention, and FIG. 17 is a cross-sectional view taken along line I to I' of FIG. 16.

16 and 17, the liquid crystal display device according to the second embodiment of the present invention extends the light guide plate 650 to the lower side of the light incident area to form the first and second light incident portions 220a and 220b and the third light incident area. The light receiving part 300 or 310 may be raised above the light guide plate 650. In this case as well, for guiding light, the first and second light sources 110 and 120 are placed only on the sides of the first light incident part 220a and the third light incident part 300 or 310.

In this case, the second light incident portion 220b is rectangular in plan, and its height may gradually decrease from the side adjacent to the first light incident portion 220b toward the opposite side.

In this case, looking at the path of light, the light source passing through the first light source 110 selectively passes through the first light incident portion 220a, moves horizontally, and bends downward through the inclined second light incident portion 220b. It is incident on the light guide plate 650, is propagated within the light guide plate 650, and passes through the film-shaped light extraction pattern 800 provided on the exit surface of the light guide plate 650 to the upper image panel 500. It can be transmitted as . In this structure, since the light incident part (optical coupler) is placed on the light guide plate 650, a second light incident part (light coupler) is provided so that the light guided in the horizontal direction from the light source 110 or 120 can be bent toward the light guide plate 650. A slope was given to the 220b) side.

Here, the light extraction film 800 is a type of optical film, and has a regular groove-shaped light extraction pattern to transmit light traveling from the light guide plate 650 in the upward direction.

Hereinafter, we will look at data testing the optical effects of the display for viewing mode control of the present invention.

Figure 18 is a cross-sectional view showing the configuration of a backlight unit used in a liquid crystal display device according to a second embodiment of the present invention, and Figures 19a and 19b show the light intensity according to angle for each region during an experiment using Figure 18. It's a graph.

Figure 18 shows the configuration of the backlight unit below the image panel provided on the upper side as a liquid crystal panel (not shown), including the above-described first and second light incident portions 220a and 220b and the adhesive layer 230. ) is attached to the light guide plate 650. If the third light incident part 310 is made of a specific medium other than air, the third light incident part 310 is also attached to the light guide plate 650.

In the above experiment, the first light incident part 220a and the second light incident part 220b were formed of a specific medium, and the first light incident part 220a and the second light incident part 220b had a refractive index of 1.4244, for example. The thickness was set to 0.5mm, and the inclination angle was set to 5°.

In addition, the light guide plate 650 is made of the same material as the first and second light incident portions 220a and 220b, and only has a different thickness of 1 mm, and the light extraction film 800 on the upper side of the light guide plate 650 is slightly thicker than them. It was made of a material with a high refractive index of 1.5, and its thickness was 0.1 mm. In addition, the adhesive layer 230 had a thickness of 0.1 mm, and a material with a refractive index of 1.3407, which was lower than that of the first light incident portion 220a, was used.

In the above experiment, an absorbing portion 660 was placed on the lower side of the light guide plate 650 corresponding to the first light incident portion 220a, which had a width of 10 mm and a thickness of 0.1 mm, and the first and first light sources 110 and 120 ), in the longitudinal direction corresponding to the first light incident portions 220a, to prevent light from escaping to the lower side of the light guide plate 650.

In this structure, the light source had an illuminance of 100 lm and an effective area of 0.4 mm x 0.4 mm.

In this case, as shown in FIG. 19B, the light passing through the first light incident portion 220a had a peak value around 0° with respect to the center of the light source, and the full width at half maximum was equivalent to 16°. The light passing through the first light incident part 220a and transmitted to the light guide plate 650 is deflected at the inclined second light incident part 220b and is totally reflected up and down within the light guide plate 650, resulting in the transmission of light as shown in Figure 19a. Likewise, the peak occurs at 58°, and its half width corresponds to 7.2°. That is, it can be confirmed that the light passing through the light guide plate 650 has a narrower width and the emission angle has been reduced, thereby confirming that the privacy mode can be implemented.

FIG. 20 is a plan view showing a liquid crystal display device according to a third embodiment of the present invention, and FIG. 21 is a cross-sectional view taken along line II to II' of FIG. 20.

20 and 21, in the liquid crystal display device according to the third embodiment of the present invention, the shape of the light guide plate 670 located on the lower side of the image panel 500 is wedge-shaped, and the thickness of the light incident area is was thickened and implemented in a form with a thickness that gradually decreases toward the opposite side of the light entrance. In this case, like the liquid crystal display device of the first embodiment described above, the first and second light incident portions 210a and 210b maintain the same thickness, and the thickness at this time is equal to the light incident portion of the light guide plate 670. It was made the same as the side thickness.

In this case, the first and second light incident parts 210a and 210b are provided with reflectors 410a and 410b above and below, thereby preventing light from escaping in the vertical direction. Here, the reflectors 410a and 410b may also be provided between the first light incident parts 210a, and as a result, the reflectors 410a and 410b are located above and below the light incident parts in a sheet form corresponding to the horizontal surface of the light incident parts. can do.

In the third embodiment of the present invention, the first light source 110 is located corresponding to the first light incident portion 210a.

Additionally, a low refractive index layer 810 and a light extraction film 850 having a lower refractive index than that of the light guide plate 670 are provided on the upper side of the light guide plate 670. In this case, the light extraction film 850 has the same configuration as the second embodiment described above. In this case, a first medium layer 810 with a lower refractive index than the light guide plate and a regular groove-shaped light extraction pattern layer 850 are located on the light guide plate at the light emitting portion (upper side of the light guide plate excluding the light incident area). , extraction of light to the upper side is possible. Here, the light extraction pattern layer 850 may be defined by forming a regular groove pattern in a medium layer with a higher refractive index on the first medium layer 810, or on the surface of the first medium layer 810. It may also be defined by forming a physical groove.

In addition, the second light source 120 is placed in the same row between the first light sources 110, and the privacy mode and wide viewing angle mode can be selectively controlled by selectively driving them.

Figure 22 is a graph showing luminance characteristics by angle in privacy mode and wide viewing angle mode during an experiment using the liquid crystal display device according to the present invention.

As shown in Figure 22, when forming a liquid crystal display device by providing the optical coupler for controlling the viewing mode of the present invention on the side of the light guide plate, in the privacy mode, light is emitted within 20° of the half width in the peak area, and the light is limited to a certain area. This means that exposure is possible, which indicates that privacy mode is possible. Additionally, in the wide viewing angle mode, the range of output light is distributed from the center of the light to ±90° around, confirming that the wide viewing angle mode is possible.

That is, when equipped with the optical coupler for controlling the viewing mode of the present invention, it is possible to selectively implement the privacy mode and the wide viewing angle mode.

Meanwhile, the above-described liquid crystal display device is a light-receiving video panel, and shows an example of using a liquid crystal panel. If it is a light-receiving video panel that requires a backlight unit in addition to the liquid crystal panel, a backlight unit of the above-described configuration can be configured on the lower side of the display panel. You will be able to.

Meanwhile, the present invention described above is not limited to the above-described embodiments and the accompanying drawings, and various substitutions, modifications, and changes are possible without departing from the technical spirit of the present invention. It will be clear to a person with ordinary knowledge.

110: first light source 120: second light source
210a, 220a: first light entrance part 210b, 220b: second light entrance part
230: Adhesive layer 300, 310: Third light entrance
410a, 410b: Reflector 500: Image panel
550: Inverted prism sheet 600, 650, 670: Light guide plate
610: Light extraction pattern 700: Reflector
800: Light extraction film 660: Absorption unit

Claims (22)

first and second light sources each having a light emitting surface of a first width and a light emitting surface of a second width longer than the first width, and arranged alternately in the same row;
first light incident portions having a first side corresponding to the light emitting surface of the first width and, opposite to the first side, a second side of a third width greater than or equal to the second width, and being trapezoidal in plan; and
and a second light incident portion adjacent to second sides of the first light incident portion corresponding to the first light source,
When the first light source is turned on, the light emitted through the light emitting surface of the first light source travels straight through the first light incident parts and is transmitted to the second light incident parts,
When the second light source is turned on, the light emitted through the light emitting surface of the second light source passes through the third light incident part between the first light incident parts and is emitted to the first light incident parts, and the second light incident part Optocoupler for viewing mode control delivered to . According to clause 1,
An optical coupler for viewing mode control, wherein the first light incident parts and the second light incident parts are filled with a first medium having a first refractive index. According to clause 2,
An optical coupler for viewing mode control is defined as a third light incident part between the first light incident parts and the second light source in a plan view, and is triangular in plan view. According to clause 3,
An optical coupler for viewing mode control in which the third light incident part is empty. According to clause 3,
The third light incident portion is filled with a medium having a second refractive index lower than the first refractive index. According to claim 4 or 5,
An optical coupler for viewing mode control further comprising a first reflector above the first light incident portion and the third light incident portion, and a second reflector below the first light incident portion. delete According to clause 3,
The first light incident part is an optical coupler for viewing mode control in which the trapezoid in plan has the same height. According to clause 8,
The second light incident portion is rectangular in plan and has the same height as the first light incident portion. According to clause 8,
The second light incident portion is rectangular in plan, and the height gradually decreases from the side adjacent to the first light incident portion to the opposite side. first and second light sources each having a light emitting surface of a first width and a light emitting surface of a second width longer than the first width, and arranged alternately in the same row;
First light incident portions having a first side corresponding to the light emitting surface of the first width and, opposite to the first side, a second side of a third width greater than or equal to the second width, and being trapezoidal in plan, and the first light receiving portions a light incident area including a second light incident unit adjacent to second sides of the first light incident unit corresponding to one light source;
a light guide plate in contact with the second light incident portion;
an inverted prism sheet located on the light guide plate; and
It includes a reflector located below the light guide plate,
When the first light source is turned on, the light emitted through the light emitting surface of the first light source travels straight through the first light incident parts and is transmitted to the second light incident parts,
When the second light source is turned on, the light emitted through the light emitting surface of the second light source passes through the third light incident part between the first light incident parts and is emitted to the first light incident parts, and the second light incident part Backlight unit delivered to. According to clause 11,
The upper surface of the light guide plate faces the prism surface of the inverted prism sheet,
The lower surface of the light guide plate has a plurality of straight light extraction patterns parallel to the second light incident portion,
A backlight unit in which one side of the light guide plate is in contact with the light incident area. According to claim 11,
A backlight unit in which an area between the first light incident parts has a lower refractive index than the first light incident parts. According to clause 12,
The straight light extraction pattern is a backlight unit provided concavely on the lower surface of the light guide plate. According to clause 12,
A backlight unit in which light is transmitted in parallel from the light incident area to the light guide plate, and the light guide plate scatters the light up and down through the light extraction pattern and transmits the light to the inverted prism sheet to the upper side. delete According to clause 11,
The first light incident portion is a backlight unit in which the trapezoid in plan has the same height. According to clause 11,
The light incident area is a backlight unit located above the light guide plate. According to clause 18,
The second light incident portion is rectangular in plan, and the height of the backlight unit gradually decreases from the side adjacent to the first light incident portion to the side opposite the light guide plate. According to clause 11,
The light guide plate is in contact with the side of the light incident area,
The light guide plate has the same height as the light incident area on the side adjacent to the light incident area, and gradually decreases in height toward the opposite side. According to clause 20,
a first medium layer having a lower refractive index than the light guide plate on the light guide plate;
A backlight unit further comprising a regular groove-shaped light extraction pattern on the first medium layer that transmits light upward in the direction of light. The backlight unit of any one of claims 11 to 15 and 17 to 21; and
A display for viewing mode control including a light-receiving image panel located on the backlight unit.