KR20220022509A - Backlight unit of display device and display device having the same for vehicle - Google Patents

Abstract

The present invention discloses a backlight unit for a display device capable of controlling a viewing angle and a vehicle display device having the same. The backlight unit of the embodiment comprises: a light guide plate having a pair of long sides facing each other in a shape of a rectangular plate and another pair of short sides facing between the pair of long sides; a first light source disposed on one side of a long side of the light guide plate; a second light source disposed on both short sides of the light guide plate; and an optical sheet disposed on the front surface of the light guide plate. The viewing angle is limited in the front direction by driving the first light source, and expands in the lateral direction by driving the second light source.

Description

A backlight unit for a display device capable of controlling a viewing angle, and a vehicle display device having the same

Disclosed are a backlight unit for a display device capable of controlling a viewing angle, and a vehicle display device having the same.

In general, a liquid crystal display device is a display device in which a desired image can be displayed by individually supplying data signals according to image information to pixels arranged in a matrix form, and adjusting the light transmittance of the pixels. Since the liquid crystal display does not emit light by itself and is a light-receiving element that displays an image by controlling the transmittance of light coming from the outside, a separate device for irradiating light to the liquid crystal panel, that is, a backlight unit is required.

The backlight unit includes a light source, a light guide plate, a reflection plate, and a plurality of optical sheets. The light source may be disposed on the side of the region corresponding to the side surface of the light guide plate, and the reflection plate may be disposed on the rear surface of the light guide plate. The plurality of optical sheets may be disposed on the light guide plate. In addition, the plurality of optical sheets may include a viewing angle control sheet for controlling the viewing angle.

In a general viewing angle control sheet, a louver pattern made of black carbon is disposed between two base films made of polycarbonate (PC) material to block light incident in an oblique direction to reduce the vertical viewing angle. giving role. Specifically, the viewing angle control sheet transmits light perpendicular to the louver pattern and blocks light incident in the oblique direction, so that the viewing angle in the louver pattern formation direction and the vertical direction can be adjusted.

The viewing angle control of the liquid crystal display may be controlled by a viewing angle control sheet, which is combined with factors such as an incident angle and an incident direction of a light source incident into the light guide plate.

On the other hand, a display device such as a liquid crystal display device is applied to various fields, and recently, a display device for a co-driver installed in a vehicle has been introduced. A display device for a co-driver is a display device installed in the passenger seat of a vehicle. When the vehicle is driving, the image is not visible to the driver, but only to the assistant. This should be controlled.

The present invention is a display device for a co-driver installed in a vehicle, wherein the viewing angle is controlled so that the image is not recognized by the driver while the vehicle is driving and the image is visible only to the driver when the vehicle is stopped, and a backlight for the display device The task is to provide units.

Another object of the present invention is to provide a display device for a vehicle that provides a surface light source of uniform luminance while controlling a viewing angle and a backlight unit therefor.

In order to achieve the above object, the backlight unit of this embodiment includes a light guide plate having a pair of long sides facing each other in a rectangular plate shape and another pair of short sides facing between the pair of long sides, and one side of the long side of the light guide plate. a first light source disposed on the light guide plate, a second light source disposed on both sides of the short side of the light guide plate, and an optical sheet disposed on the front surface of the light guide plate, wherein a viewing angle is limited in the front direction by driving of the first light source; It is configured to extend the viewing angle in the lateral direction by driving the light source.

In this embodiment, the second light source may be driven with a lower current than the first light source.

In this embodiment, the second light source may be driven with an amount of 30 to 40% of that of the first light source.

In this embodiment, the second light source may be disposed to be spaced apart from the first light source in the longitudinal direction of the short side of the light guide plate.

In this embodiment, the second light source may be disposed at a position shifted by an interval of 2 to 10% with respect to the entire length of the short side of the light guide plate.

In this embodiment, the optical sheet may include a viewing angle control sheet.

In addition, the vehicle display device of the present embodiment for solving the above problems includes a light guide plate having a pair of long sides facing each other in a rectangular plate shape and another pair of short sides facing between the pair of long sides, and a long side of the light guide plate A backlight unit including a first light source disposed on one side, a second light source disposed on both short sides of the light guide plate, and an optical sheet disposed on the front surface of the light guide plate, and disposed on the front surface of the backlight unit in the backlight unit It includes a liquid crystal panel for realizing an image by using a provided surface light source, the image is limited in the front direction by driving the first light source, and the image is expanded in the lateral direction by driving the second light source configured to be provided.

In this embodiment, the first light source and the second light source are driven by turning on only the first light source when the vehicle is driving, and both the first light source and the second light source are turned on and driven when the vehicle is not driving It can be configured to be

In the present embodiment, the driving sensor may further include a driving sensor configured to control on/off of the second light source by detecting whether the vehicle is being driven.

The present invention is a display device for a co-driver installed in a vehicle. When the vehicle is running, an image is provided only to the front co-driver, and the driver's viewing angle is limited, thereby improving driving safety.

In addition, the present invention can improve the convenience of use by providing an image to the driver when the vehicle is not driving.

Also, according to the present invention, even if the image is provided only on the front side or extended to the left and right sides, the image is provided with uniform luminance to provide a high-quality image.

1 is an exploded view showing the main configuration of a backlight unit according to the present embodiment;
Figure 2 is a plan view showing an example of the main configuration of the backlight unit of Figure 1;
3A and 3B are views showing an example of driving the display device according to the present embodiment;
4 is a plan view showing another example of the main configuration of the backlight unit according to the present embodiment.

The present invention and the technical problems achieved by the practice of the present invention will be made clear by the preferred embodiments described below. Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

It should be understood that the differences between the embodiments described below are not mutually exclusive. That is, without departing from the spirit and scope of the present invention, the specific shapes, structures and characteristics described may be implemented in other embodiments with respect to one embodiment, and the location of individual components within each disclosed embodiment Or it should be understood that the arrangement may be changed, and similar reference numerals in the drawings refer to the same or similar functions over several aspects, and the length, area and thickness, etc., may be exaggerated for convenience. In the description of this embodiment, top, bottom. Expressions such as left, right, first, second, etc. indicate relative positions, directions, and sequences, and their technical meanings are not limited by dictionary meanings.

1 is an exploded view illustrating a main configuration of a backlight unit according to an exemplary embodiment, and FIG. 2 is a plan view illustrating an example of a main configuration of the backlight unit of FIG. 1 .

Referring to these drawings, the backlight unit of the present embodiment includes a light guide plate 100 , a light source module 200 disposed on the side of the light guide plate, and an optical sheet 300 disposed on the light guide plate. They are assembled while being accommodated in the cover bottom (not shown), and then assembly is fixed by a guide panel (not shown) fastened to the cover bottom. In addition, a liquid crystal panel (not shown) is seated on the guide panel to constitute a display device.

Specifically, the light guide plate 100 is a light conversion device that converts light from a plurality of point light sources incident from the light source module 200 into a planar light source through total internal reflection and provides the light to the liquid crystal panel. The light guide plate 130 is made of a transparent acrylic resin having a predetermined refractive index. can

The light guide plate 100 has a rectangular plate shape having a predetermined thickness, a rear surface constitutes a reflective surface, and a front surface constitutes a light exit surface for emitting light. In addition, the light guide plate 100 has four side surfaces, and the four side surfaces include a pair of long sides 100a facing each other and another pair of short sides 100b facing each other between the pair of long sides. Accordingly, the light guide plate 100 is configured as a rectangular plate having a pair of long sides 100a and another pair of short sides 100b.

The long side of one side of the light guide plate 100, for example, the upper long side 100a and the short side 100b on the left and right sides of the long side, constitute a light incident surface. Accordingly, the light source module 200 is disposed on the side of the upper long side 100a and the short side 100b on the left and right sides of the long side. The light incident into the light guide plate 100 through three light incident surfaces is emitted through the front light exit surface while undergoing total internal reflection.

A light pattern (not shown) for controlling an emission angle may be formed on the rear surface or the front surface of the light guide plate 100 . Accordingly, the light guide plate 100 may be configured to emit light in a viewing angle direction of one side. In addition, the light pattern is designed to have an optimized pattern shape in response to the driving of the first light source 200a disposed on the upper long side. Accordingly, as the distance from the first light source 200a increases, the density ratio of the light pattern may increase or the diameter of the pattern may decrease.

The light source module 200 is a light emitting source of a backlight unit that provides light to the inside of the light guide plate 100 , and may be configured as an LED array in which a plurality of LEDs 220 are mounted on a substrate 210 . The light source module 200 is disposed such that the light output surface of the LED 220 faces the light input surface of the light guide plate 100 .

In addition, the light source module 200 is disposed on one side long side 100a and opposite side short sides 100b of the light guide plate 100 . Accordingly, the light source module 200 includes a first light source 200a disposed on one long side of the light guide plate 100 and a second light source 200b disposed on both short sides of the light guide plate 100 . The first light source 200a and the second light source 200b may be driven simultaneously or may be driven independently. The first light source 200a injects light in a single direction of the light guide plate 100 , and a pair of second light sources 200b injects light in a long direction of the light guide plate 100 .

The optical sheet 300 condenses and diffuses light emitted from the light guide plate 100 to improve luminance and luminance uniformity of the backlight unit. The optical sheet 300 may be composed of a plurality of light control sheets including a prism sheet and a diffusion sheet. In addition, the optical sheet 300 may include a viewing angle control sheet as necessary, and depending on the direction of light passing through the sheet, light may or may not be emitted in a specific direction.

In the backlight unit having the above configuration, the image of the liquid crystal panel may or may not be viewed in a specific direction depending on whether the second light source 200b is driven. In the present embodiment, when the second light source 200b is not driven, for example, when only the first light source 200a is driven, the viewing angle is limited only in the front direction, so that the image is not viewed in the side direction. In addition, when both the first light source 200a and the second light source 200b are driven, the overall light amount of the backlight unit increases and the viewing angle is enlarged in the lateral direction, so that the image is viewed from both the front and the side.

Therefore, the backlight unit of the present embodiment is used as a display device for a co-driver of a vehicle, and the viewing angle can be controlled so that the driver can or cannot view the image depending on whether the vehicle is driving.

3A and 3B are diagrams illustrating an example of driving the display device according to the present embodiment.

First, as shown in FIG. 3A , when the backlight unit is driven only by the first light source 200a, the image of the display device is viewed only at the Co-Driver position and not at the Driver position. Accordingly, when the vehicle is in the driving mode, the first light source 200a is turned on and the second light source 200b is turned off so that the image of the display device does not interfere with the driver.

Also, as shown in FIG. 3B , when the backlight unit is driven by both the first light source 200a and the second light source 200b, the image of the display device is viewed at both the co-driver and driver positions. Therefore, when the vehicle is not driving, that is, in the stop mode, both the first light source 200a and the second light source 200b are turned on so that the driver can also view the image of the display device.

In this case, the on-off of the second light source 200b may be configured to be manually controlled according to a user's manipulation. In addition, it will be preferable for safe driving that the on-off of the second light source 200b is configured such that a sensor for detecting whether the vehicle is being driven is separately provided and automatically controlled by the sensor.

Meanwhile, in the light source module 200 , the first light source 200a and the second light source 200b have different driving currents. That is, the first light source 200a is driven with a current of 100% according to the original function of the light source module 200, and the second light source 200b has a current of 30% to 40% compared to the first light source 200a. is driven by That is, the second light source 200b provides light having a luminance of 30% to 40% compared to that of the first light source 200a.

Light from the second light source 200b is incident from both side light incident surfaces of the light guide plate 100 and overlaps with light incident from the upper light incident surface. In this case, the luminance increases in the vicinity of the second light source 200b on both sides and the luminance is relatively low in the central region of the light guide plate 100 , resulting in a luminance imbalance. Therefore, it is preferable that the second light source 200b, which injects light through both side light incident surfaces of the light guide plate 100, is driven with a current of 30% to 40% compared to the first light source 200a. When the second light source 200b is driven with an amount of current less than 30%, the effect of increasing the luminance is not large, so the image may not be recognized by the driver, and when the amount of current exceeds 40%, a hot spot may appear. .

4 is a plan view showing another example of the main configuration of the backlight unit of the present embodiment.

In the backlight device according to the present embodiment, the second light source 200b is disposed by being moved in the short axis direction. That is, as shown, the position of the second light source 200b is moved to be spaced apart from the first light source 200a by a predetermined distance (L). In this case, the second light source 200b is positioned to move downward by a distance L corresponding to 2% to 10% of the entire length of the short side 100b of the light guide plate 100 .

When the second light source 200b of the short side 100b is disposed on the side of the light guide plate 100 so that the second light source 200b of the long side 100a is in contact with the first light source 200a of the long side 100a, the light is concentrated in the corner region of the light guide plate 100 in contact with them. A hot spot such as a light splashing phenomenon may occur. Accordingly, when the second light source 200b is spaced apart from the first light source 200a in the corner region of the light guide plate 100, such a hot spot can be improved.

Table 1 shows experiments and measurements of light distribution data according to the separation distance L of the second light source 200b. In this experiment, the second light source 200b was driven with a current of 33%.

division distance traveled
(compared to shortened length) drive current
(Compared to the first light source) Light distribution data judgment One 2% 33%

Good 2 4% 33%

Good 3 6% 33%

Good 4 8% 33%

Good 5 10% 33%

error

As can be seen from Table 1 above, the second light source is preferably moved at a distance of 2% to 10% of the total length with respect to the short side of the light guide plate. This is because, when the movement distance L of the second light source is less than 2%, the light splashing phenomenon due to the overlapping of the light is not improved, and when the movement distance L of the second light source is greater than 10%, dark dark areas are generated in the corner area.

Accordingly, the second light source 200b is disposed to be moved at a distance of 2% or more and less than 10% of the short side length of the light guide plate 100 , and uniform luminance can be maintained as a whole regardless of whether the second light source 200b is driven. In the present embodiment, when the second light source 200b is disposed and driven at the above position, it was possible to maintain uniformity of 85% or more as a whole.

As described above, although exemplary embodiments of the present invention have been illustrated and described, various modifications and other embodiments may be made by those skilled in the art. All such modifications and other embodiments are intended to be contemplated and included in the appended claims without departing from the true spirit and scope of the present invention.

100: light guide plate
100a: long side 100b: short side
200: light source module
200a: first light source 200b: second light source
300: optical sheet

Claims (9)

a light guide plate having a rectangular plate shape and having a pair of facing long sides and another pair of short sides facing between the pair of long sides;
a first light source disposed on one side of a long side of the light guide plate;
a second light source disposed on both short sides of the light guide plate;
Including; an optical sheet disposed on the front surface of the light guide plate;
and a viewing angle is limited in a front direction by driving of the first light source, and a viewing angle is extended in a lateral direction by driving of the second light source. The method of claim 1,
The second light source is driven with a lower current than the first light source, a backlight unit for a display device. In claim 2,
The second light source is driven by an amount of 30 to 40% of that of the first light source, the backlight unit for a display device. The method of claim 1,
The second light source is disposed to be spaced apart from the first light source in a longitudinal direction of a short side of the light guide plate. 5. The method of claim 4,
The second light source is disposed at a position shifted by an interval of 2 to 10% with respect to an entire length of a short side of the light guide plate. The method of claim 1,
The optical sheet includes a viewing angle control sheet, a backlight unit for a display device. A light guide plate having a pair of long sides facing each other in a rectangular plate shape and another pair of short sides facing between the pair of long sides, a first light source disposed on one side of the long side of the light guide plate, and both short sides of the light guide plate A backlight unit comprising: a second light source disposed on
a liquid crystal panel disposed on the front surface of the backlight unit to realize an image using a surface light source provided from the backlight unit;
The display device for a vehicle is configured to provide the image limited in the front direction by driving the first light source, and to expand and provide the image in the lateral direction by driving the second light source. 8. The method of claim 7,
The first light source and the second light source are
When the vehicle is driving, only the first light source is turned on and driven, and when the vehicle is not driving, both the first light source and the second light source are turned on and driven. 9. The method of claim 8,
The display apparatus for a vehicle further comprising a driving sensor configured to control on/off of the second light source by detecting whether the vehicle is being driven.

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