WO2018016691A1 - Backlight unit and liquid crystal display apparatus including same, and backlight unit dimming method - Google Patents

Abstract

The present invention relates to a backlight unit and a liquid crystal display apparatus including same. The backlight unit can realize a more subdivided and precise local dimming when compared to the related art, and can further improve power consumption, luminance, visibility, a contrast ratio, or the like when compared to the related art. The backlight unit according to the present invention comprises: a light source part; and a light guide plate part onto which light is incident from the light source part. The light guide plate part comprises: a light guide plate main body; a first light incident part which is formed on one side surface portion of the light guide plate main body and onto which light is incident; and a second light incident part which is formed on the other side surface portion of the light guide plate main body and onto which light is incident. The light source part is characterized by including a first array made of a plurality of light emitting devices and disposed on the first light incident part side, and a second array made of another plurality of light emitting devices and disposed on the second light incident part side.

Description

Backlight unit, liquid crystal display including the same, and backlight unit dimming method

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display, and more particularly, to a backlight unit and a dimming method thereof for realizing finer and more precise local dimming in the conventional local dimming of the liquid crystal display.

Currently, smart phones are actively researching and developing technologies for keeping battery power long due to portability, and there is a great demand for reducing power consumption of consumers.

In the current display market, liquid crystal displays (LCDs) are dominant, and these LCD displays are continuously developed and have a clearer effect on people through technology such as having 3D-like functions or increasing the number of pixels such as UHD. Technological advances are being made to deliver image quality. This development requires that the backlight, which plays a role of emitting light from the back side, also has a differentiating technology.

While current LCDs require low power consumption technology for backlights, which account for 70% of the power consumption, notebooks, tablets, and smartphones that use small and medium-sized displays require edge type (Edge) due to the demand for portability and light weight. type of backlight is mainly used.

Current liquid crystal display divides the backlight into multiple areas for efficient power consumption of the backlight, and the brightness is linked with the image signal, so that the dark areas of the image are turned off or the light is reduced, and the bright areas are increased. In this case, a local dimming method that significantly improves the contrast ratio and power consumption has been applied.

In order to implement such a local dimming technology more effectively, the backlight driving area needs to be subdivided into a larger number, and in particular, the driving of the upper area and the lower area of the LGP must be controlled separately.

However, in the conventional liquid crystal display, due to problems such as an increase in the bezel size and an optical length of the backlight unit, a light source is disposed only on one side of the light guide plate to implement local dimming using only one light source, as in the first patent. Conventional and for this reason, there is a limitation in the current backlight unit structure that it is difficult to implement more precise and fine local dimming.

Prior Art Documents Korean Patent Publication No. 2015-0062857 (2015.06.08)

The present invention has been made to solve the above problems, and an object of the present invention is to provide a backlight unit capable of realizing more precise and finely divided local dimming.

It is still another object of the present invention to provide a backlight unit that can overcome the optical length reduction limit of the conventional backlight unit and can eventually reduce the bezel size of the liquid crystal display device.

Still another object of the present invention is to provide a backlight unit capable of further improving performances such as power consumption, brightness, visibility, contrast ratio, and the like.

The backlight unit according to the present invention for achieving the above object is a light source; And a light guide plate portion through which light is incident from the light source portion.

The light guide plate portion includes a light guide plate body, a first light incident portion formed at one side of the light guide plate body to receive light, and a second light incident portion formed at the other side portion of the light guide plate body to receive light.

The light source unit includes a first array composed of a plurality of light emitting elements and disposed on the side of the first light incident unit, and a second array composed of another plurality of light emitting elements and disposed on the side of the second incident light unit.

Preferably, each of the first light incident portion and the second light incident portion includes a serration pattern formed in a sawtooth shape, and the backlight unit has a first separation distance of 3.2 mm between the light emitting screen of the light guide plate body and the light emitting elements of the first array. It is formed less than, the second separation distance between the light-emitting screen of the light guide plate body and the light emitting device of the second array is formed less than 3.2mm, the serration pattern is formed the pitch of the tooth is less than 0.06mm.

According to an embodiment of the present invention, a backlight unit may include a driver configured to adjust brightness of a plurality of unit light emitters, respectively; And receiving the image data signal, analyzing the image data signal for each unit driving region, finding the brightest reference pixel for each unit driving region, and determining a reference value for each unit driving region based on the position and brightness of the reference pixel. It may include a control unit for generating a control signal according to the reference value for each unit driving region and transmits the control signal.

The controller is further configured to find a brightest reference pixel for each unit driving region by analyzing a receiver for receiving an image data signal and the image data signal for each unit driving region, and for each unit driving region based on the position and brightness of the reference pixel. And a signal generator for generating a control signal according to the determined reference value for each unit driving region.

According to the backlight unit and the liquid crystal display device according to the present invention, it is possible to implement more detailed and precise local dimming compared to the conventional dimming, to further improve the brightness, contrast ratio, visibility, etc. of the display device, power consumption 5 ~ compared to the conventional 20% more can be saved.

According to the backlight unit and the liquid crystal display device according to the present invention, it is possible to manufacture a backlight unit having an optical length shorter than the conventional optical length threshold, so that the bezel into a further improved one-side bezel size compared to the conventional There is an advantage that can be implemented.

1 is an exploded perspective view of a liquid crystal display according to the present invention.

2 is a plan view of a backlight unit according to the present invention;

3 is a side view of the backlight unit according to the present invention;

4 is a sectional view of a backlight unit according to the present invention;

5 is a perspective view of the light guide plate portion according to the present invention.

6 is a cross-sectional view showing a serration pattern in accordance with the present invention.

7 is a plan view showing a unit light emitter and a unit driving region according to the present invention.

8 is a simulation data showing a hot spot phenomenon for each pitch of the serration pattern of the present invention.

9a and 9b are comparative graphs showing the relative sizes of hot spots for each pitch of the serration patterns of the present invention.

10 is an exemplary view for explaining local dimming according to the present invention.

11 is a view schematically showing an embodiment of a backlight unit according to the present invention.

12 is a diagram illustrating an example of reference values for respective unit driving regions of the present invention.

FIG. 13 is a view illustrating luminance by location of the entire light guide plate when the unit light emitting unit of the present invention is driven.

FIG. 14 is a view illustrating luminance by position of a light guide plate when a corresponding unit light emitter is driven such that the luminance of a reference pixel of the reference unit driving region of the present invention is 100;

[Description of the code]

10: light guide plate body 20: first array

21: light emitting device of the first array 22: second array

23: light emitting element of the second array 31: first light incident part

32: second light incident portion 35: light incident surface of the first light incident portion

37: Light incident surface of the second light incident portion 40: Shielding layer

50: frame 60: drive part

70: control unit 100: liquid crystal display panel

110: prism sheet 120: diffusion sheet

130: light source unit 140: backlight unit

145: Light guide plate 150: Reflective sheet

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. As used herein, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, action, component, part, or combination thereof described on the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

In addition, in the present specification, "on or above" means to be located above or below the target portion, and does not necessarily mean to be located above the gravity direction. In addition, when a portion such as an area, a plate, etc. is said "on or on top of" another part, it is not only in contact with or spaced apart from another part, but also in the middle of another part. It also includes cases where there is.

In addition, in the present specification, when one component is referred to as "connected" or "connected" with another component, the one component may be directly connected or directly connected to the other component, but in particular It is to be understood that, unless there is an opposite substrate, it may be connected or connected via another component in the middle.

Also, in this specification, terms such as first and second may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment, advantages and features of the present invention.

1 is an exploded perspective view of a liquid crystal display according to the present invention, FIG. 2 is a plan view of a backlight unit according to the present invention, FIG. 3 is a side view of the backlight unit according to the present invention, and FIG. 4 is a backlight unit according to the present invention. 5 is a perspective view of a light guide plate portion according to the present invention.

1 to 5, the liquid crystal display according to the present invention includes a liquid crystal display panel 100 on which an image is displayed and a backlight unit 140 for providing light to the liquid crystal display panel 100.

The liquid crystal display panel 100 includes a pair of substrates disposed to face each other and a liquid crystal layer interposed between the pair of substrates, and a pixel region is defined by a plurality of gate lines and data lines arranged in a matrix form on the substrate. do. A thin film transistor for controlling a signal supplied to each pixel and a pixel electrode connected to the thin film transistor are formed on a substrate where the gate line and the data line cross each other, and a color filter and a common electrode are formed on the other substrate. In addition, polarizers may be provided on the rear surfaces of the two substrates, respectively.

The backlight unit 140 may include a light source unit 130 for emitting light, a light guide plate unit 145 for changing a distribution of light provided from the light source unit 130, and a light guide unit 145. The optical sheets 110 and 120 to uniform the luminance distribution and improve the vertical incidence, and the reflective sheet 150 for injecting light emitted to the rear of the light guide plate body 10 into the light guide plate.

The light source unit 130 includes a plurality of light emitting devices disposed on both side surfaces of the light guide plate 145, and a reflecting plate reflecting light emitted from the light emitting device toward the light guide plate. The light emitting device is preferably composed of a point light source such as an LED (Light Emitting Diode (LED)), but may be a tube light source such as a cold cathode tube (fluorescent lamp) that emits white light.

The light source unit 130 may be divided into a first array 20 disposed on one side of the light guide plate 145 and a second array 22 disposed on the other side.

The first array 20 is composed of a plurality of light emitting elements 21, and the light emitting elements 21 are arranged in a line at a distance from each other on the same axis. The first array 20 is disposed on the first light incident part 31 side of the light guide plate 145. More specifically, in the first array 20, the light emitting device 21 configuring the same is disposed to face the light incident surface 35 of the first light incident portion 31, that is, the serration pattern SP to be described later. Preferably, the light exit surface of the light emitting element 21 is disposed in contact with the light incident surface 35.

The second array 22 is made up of another plurality of light emitting elements 23, and the light emitting elements 23 are arranged in a row at a distance from each other on the same axis. The second array 22 is disposed on the second light incident part 32 side of the light guide plate 145. More specifically, in the second array 22, the light emitting device 23 configuring the same is disposed to face the light incident surface 37 of the second light incident part 32, that is, the serration pattern SP to be described later. Preferably, the light exit surface of the light emitting element 23 is disposed in contact with the light incident surface 37.

The optical sheet may include a diffusion sheet 120 for diffusing light incident from the light guide plate body 10 toward the liquid crystal display panel 100 and a prism sheet 110 for condensing the diffused light to improve vertical incidence. Can be.

Reflective sheet 150 is for reflecting the light emitted to the lower portion of the light guide plate body 10 to be re-incident into the light guide plate body 10, any conventional reflective sheet used in the art can be used without particular limitation. .

The light guide plate 145 includes a light guide plate body 10 and light receiving parts 31 and 32, and the light guide parts 31 and 32 are formed on both side surfaces of the light guide plate body 10, respectively.

The light guide plate body 10 is configured to uniformly change the optical distribution concentrated in a narrow area over a large area. The surface light source having uniform luminance by repeating total reflection and refraction of point light or linear light incident from the light source unit 130 inside After converting to the outside, exiting.

In this case, the surface light source emission area of the light guide plate body 10 is referred to as an "effective screen or effective area of the backlight unit 140". In the present invention, such an effective screen or an effective area (Light Area) of the backlight unit 140 will be referred to as a light output screen (L / A). The light exit screen L / A may correspond to the remaining areas of the entire upper surface of the light guide plate except for the area where the light exit is shielded by the shielding layer 40.

On the other hand, in contrast to the light exit screen L / A, there is an active area (A / A). The active area A / A refers to an effective area in which an image is substantially displayed on the liquid crystal display panel 100. In general, a portion of the light exit screen L / A is used as the active area A / A. .

That is, the liquid crystal display generally has a larger size of the light exit screen L / A than the active area A / A, and typically has the active area A / A several mm on one side K1. For example, an area grown 0.3 mm corresponds to the light exit screen L / A.

The light guide plate body 10 is a thin plate or film member formed of a transparent resin material, the shape of which may be formed in a rectangular shape, and as a usable resin material, an acrylic resin such as polymethyl methacrylate (PMMA) is typically used. In addition, polycarbonate resin, styrene resin, olefin resin, polyester resin, etc. can be used besides this.

In addition, the light guide plate body 10 may have light scattering patterns 11 and 13 formed on at least one surface to supply a uniform surface light source. The light scattering patterns 11 and 13 may be formed in an embossed pattern such as a dot / round-prism / triangular-prism pattern / lenticular pattern or in an intaglio pattern such as a U cut / V cut / lenticular pattern. .

The light scattering patterns 11 and 13 may be provided for light scattering and may be integrally formed on the light guide plate body 10, and may be formed by a direct processing method, an etching method, a laser processing method, or a sand blasting method.

The light scattering patterns 11 and 13 are configured to have a structure in which the spacing between neighboring intaglios (or reliefs) decreases toward the central portion C1 and is gradually densely arranged. In other words, as the distance from the light source unit 130 increases, the gap becomes dense.

Accordingly, in the backlight unit 140 of the present invention, the light source portions 130 are provided at both sides of the light guide plate body 10, and the left light scattering pattern 11 based on the central portion C1 is the first array as shown in FIG. 3. The pattern spacing gradually becomes denser as it faces from the 20 to the center portion C1, and the pattern spacing gradually becomes denser as the other light scattering pattern 13 faces the center portion C1 from the second array 22, so that the light guide plate body 10 In the center of the c).

On the other hand, the light scattering pattern may be configured to gradually increase the size of the embossed (or intaglio pattern) toward the central portion (C1) of the light guide plate body 10.

The light incident part is an area in which light emitted from the light source part 130 is incident, and is formed in one side part (lower side part in FIG. 2) of the light guide plate body 10 to receive light emitted from the first array 20. The first light incident part 31 and the second light incident part 32 formed on the other side part of the light guide plate main body 10 (upper side part in FIG. 2) to which light emitted from the second array 22 is incident are formed. . For reference, the "lower side part" refers to one side edge portion of the light guide plate body 10, and the "upper side part" refers to the opposite edge portion of the "lower side portion".

The first light incidence part 31 and the second light incidence part 32 may be integrally formed on the light guide plate body 10, or may be separately molded to have a lens shape adjacent to or in contact with both sides of the light guide plate body 10. It can also be configured.

Meanwhile, serration patterns in the form of saw teeth are formed on the light incident surface 35 of the first light incident portion 31 and the light incident surface 37 of the second light incident portion 32. The serration pattern increases the angle at which light enters and widens the scattering range.

6 is a cross-sectional view showing a serration pattern according to the present invention. Referring to Figure 6 will be described in detail with respect to the features of the serration (Serration) pattern of the present invention.

Even though the light incident on the first and second light incident portions 31 and 32 is respectively refracted according to the refractive index of the light guide plate body 10, near the light incident portion, a matt portion where the incident light does not overlap each other will appear.

When the serration patterns are provided on the light receiving surfaces 35 and 37, the light radiated radially from the light source unit 130 is incident on the light guide plate 145, and is then refracted and diffused while passing through the serration pattern SP. Will be minimized. The serration pattern SP may be formed in a sawtooth shape or a semicircular cross-sectional shape along the length direction of the light incident surface.

However, according to the serration pattern of the conventional backlight unit, when the optical length of the backlight unit is reduced to less than 3.2 mm, the light emitted from the light source unit 130 is not diffused in the light guide plate body 10 and the front surface of the BLU screen. The phenomenon to be irradiated, that is, a hot spot phenomenon occurs.

Here, the optical length of the backlight unit is a distance L1 between the light emitting screen L / A of the light guide plate body 10 and the light emitting elements 21 and 23 of the light source unit 130 as shown in FIG. 4. L2). In other words, the optical lengths L1 and L2 are the distances from the ends of the light emitting elements 21 and 23 (that is, the light emitting element portions in contact with the light receiving surfaces 35 and 37) to one end of the shielding layer 40. It may be defined as. Here, the "shielding layer 40" refers to a portion located in the vertical upper portion of the light guide plate body 10 of the bezel (Bezel) region, the "one end of the shielding layer 40" is such a shielding layer 40 ) Means the lengthwise end.

This will be described in more detail as follows. In the conventional LCD, a light source is installed only on one side of the light guide plate, and accordingly, a bezel region of about 5.5 mm is formed. In other words, in order to guarantee the minimum luminance performance required for the liquid crystal display device, a light emitting device having a capacity corresponding thereto should be configured. In order to install all the light emitting devices configured on one side of the light guide plate, a bezel of about 5.5 mm may be used. Area is required. As described above, when a bezel region of about 5.5 mm was formed, an optical length of 3.2 mm or more was provided along with this. This is because, according to the conventional backlight unit structure, when the optical length is less than 3.2 mm, a hot spot phenomenon is strongly generated and the display performance is drastically degraded.

However, in the liquid crystal display of the present invention, the light source unit 130 is divided into two (that is, the first and second arrays), and each of the two light source units 130 is one on each side of the light guide plate unit 145. It is made of a structure that is installed. Accordingly, the first array 20 may be configured as a light emitting device having a smaller capacity than the conventional light source, thereby reducing the bezel area to a value smaller than that of the conventional 5.5 mm, and specifically, a bezel area of about 3.0 mm. It can be configured to have. In addition to the bezel region of about 3.0 mm, the optical lengths L1 and L2 may also be smaller than the conventional values, that is, less than 3.2 mm.

However, when the optical lengths L1 and L2 are less than 3.2 mm, a hot spot phenomenon occurs as described above. The present inventors set the pitch P1 of the serration pattern SP. When it is reduced below the threshold and the inclination angle of the serration pattern SP is formed within a predetermined angle range, it has been found that the hot spot phenomenon due to the reduction of the optical lengths L1 and L2 can be improved.

Specifically, according to the present invention, the optical length of the backlight unit 140, that is, the light exit screen L / A of the light guide plate main body 10 may be defined by the light source unit structure which is separated into two conditions and a condition to be described below of the serration pattern SP. And the separation distance L1 between the light emitting devices of the first array 20 may be less than 3.2 mm, and may be reduced to a maximum of 1.35 mm. Similarly, the separation distance L2 between the light emitting screen L / A of the light guide plate body 10 and the light emitting devices of the second array 22 may also be reduced to a range of 3.2 mm to 1.35 mm.

In order to remove the hot spot phenomenon caused by the provision of the optical length (L1, L2), the first light incident portion 31 and the second light incident portion 32 of the present invention are respectively applied to the corresponding light incident surfaces (35, 37) A serration pattern that satisfies the condition is formed.

That is, in the serration pattern SP of the present invention, the pitch P1 of the teeth is formed to be 0.06 mm or less, and the angle θ1 between the neighboring teeth is 85 ° to 95 °. Here, the "pitch pitch P1 of the teeth" means the maximum width of one tooth, which may also be expressed as the distance between the center of the first tooth and the center of the second tooth immediately adjacent thereto. In addition, the "interval between teeth (θ1)" means an angle between a pair of teeth adjacent to each other. Accordingly, when the angle θ1 between the teeth is formed at 90 °, one tooth is configured to have an upwardly inclined surface of 45 °.

8 is experimental data showing a hot spot phenomenon for each pitch of the serration pattern SP when the aforementioned optical lengths L1 and L2 are formed to be less than 3.2 mm (1.35 mm in FIG. 8), and FIGS. 9A and 9B. Is a comparison graph showing the relative magnitudes of the hot spots for each pitch of FIG. 8.

For reference, in FIG. 9A, the smaller the length of the bar is, the lower the hot spot number is. In FIG. 9B, the lower the hot spot value is, the lower the hot spot number is, and the experimental data of FIG. The angle θ1 of the liver is formed at 90 °.

As shown in Figs. 8A, 8B and 9A, 9B, when the tooth pitch P1 of the serration pattern SP is formed at the same numerical value as that of the conventional art (that is, 0.1 mm or more), the optical length Under the condition that (L1, L2) is smaller than the conventional 3.2 mm, hot spot phenomenon occurs strongly, so that the display performance required for a conventional liquid crystal display device cannot be satisfied.

By the way, the inventors of the present invention make the tooth pitch P1 of the serration pattern SP less than 0.1 mm (that is, 0,08 mm) even when the optical lengths L1 and L2 are configured to be 1.35 mm, which is considerably smaller than the conventional 3.2 mm. When formed as a result, the hot spot phenomenon is slightly improved (see Fig. 8 (c)), and in particular, when formed at 0.06 mm or less (preferably 0.04 mm or less), the hot spot value is reduced to the level required for a conventional liquid crystal display. And it was found.

That is, when the tooth pitch P1 of the serration pattern SP is formed to be 0.06 mm or less, as shown in FIGS. 8D and 9A and 9B, the hot spot value starts to drop sharply, most preferably. When formed to 0.04 mm or less, the hot spot phenomenon is drastically improved as shown in FIG. 8 (e), thereby satisfying the normal display performance required for the liquid crystal display device.

As a result, according to the backlight unit 140 according to the present invention, by separating the light source unit into two, the size of the lower bezel of the display device can be further reduced, and in particular, the optical length ( Even if L1 and L2 are also reduced, the above-described serration pattern (SP) structure can improve the hot spot value to a level suitable for a normal display device.

Hereinafter, local dimming of the present invention driven by the above-described backlight unit configuration will be described.

The backlight unit 140 of the present invention is configured such that the first array 20 and the second array 22 can be controlled to be turned on independently of each other, and the driving region is at least an upper region and a lower region of the light guide plate body 10. It is characterized by being divided.

According to a preferred embodiment, the first array 20 is composed of N light emitting elements, and the N light emitting elements are grouped by M units, and N / M (where N≥M, where N / M is a natural number) first A unit light emitter is formed, and each of the N / M first unit light emitters is configured so that its lighting and light amount are individually controlled.

Similarly, the second array 22 is composed of N 'light emitting elements, and N' light emitting elements are grouped by M 'units, and N' / M '(where N'≥M' and N '/ M' Natural unit) second unit light emitters, and the N '/ M' second unit light emitters are configured so that their lighting and light amount are individually controlled.

Accordingly, the lower region of the light guide plate body 10 of the backlight unit 140 is divided into N / M driving regions (ie, lighting regions) by N / M first unit emitters, and the upper region is N '. The driving area (i.e., the lighting area) is divided into N '/ M' pieces by the / M 'second unit light emitters, respectively, so that the display screen (i.e., the light guide plate body 10) is totally "N / M + N'. / M '' drive area (hereinafter, referred to as 'unit drive area').

The N / M first unit emitters and the N '/ M' second unit emitters have a predetermined luminance determined according to a value of current / voltage applied to each unit emitter, and local dimming is performed based on the values. It is composed.

7 is a plan view illustrating a unit light emitter and a unit driving area according to the present invention. For example, local dimming of the present invention will be described in more detail with reference to FIG. 7. The light source unit 130 of FIG. 7 includes a first array 20 of 12 (N) light emitting devices and a second array 22 of 12 (N ′) light emitting devices. In addition, the first array 20 is configured to have a first unit emitter composed of a total of 4 (N / M) and grouped into 3 (M) units, and the second array 22 is grouped into 3 (M ') units. It was configured to have a second unit light-emitting body consisting of a total of 4 (N '/ M').

In this case, the driving area of the display screen (that is, the light guide plate body 10) is largely divided into an upper area controlled by the first array 20 and a lower area controlled by the second array 22.

In addition, the lower region is divided into four unit driving regions (① to ④ of FIG. 7) in detail, and the upper region is divided into four unit driving regions (⑤ to ⑧ of FIG. 7) in detail.

More specifically, the driving (ie, lighting and luminance) of the first unit driving region ① is controlled by the first unit light emitting body including a plurality of '21a' light emitting elements, and the second unit driving region ② ) Is driven by the first unit light emitting body consisting of a plurality of '21b' light emitting devices (ie, lighting and luminance), and the third unit driving region ③ is the first unit consisting of a plurality of '21c' light emitting devices. The driving (i.e., lighting and luminance) is controlled by the unit light emitting body, and the fourth unit driving region (4) is driving (i.e., lighting and luminance) by the first unit light emitting body composed of a plurality of '21d' light emitting elements. This is controlled.

In addition, the driving of the fifth unit driving area ⑤ is controlled by a second unit light emitting body including a plurality of '23a' light emitting devices (that is, lighting and luminance), and the sixth unit driving area ⑥ includes a plurality of driving units. Its driving (i.e., lighting and luminance) is controlled by the second unit light-emitting device made up of the '23b' light emitting element, and the seventh unit driving region ⑦ is controlled by the second unit light-emitting body made up of the plurality of '23c' light emitting devices The driving (i.e., lighting and luminance) is controlled, and the driving (i.e., lighting and luminance) is controlled in the eighth unit driving region (8) by a second unit light emitting body composed of a plurality of '23d' light emitting elements.

Hereinafter, as described above, a method of realizing finer and more precise local dimming using a plurality of first and second unit light emitters and a plurality of unit driving regions will be described.

The backlight unit 140 of the present invention analyzes an image signal in a program to control brightness of a certain portion of the screen and compares and calculates the cell light amount in each unit driving region, and calculates the light amount in each unit driving region. It is configured to finally convert the screen dimming by converting the power value applied to the light emitter.

In more detail, in order to implement local dimming, the LCD is configured to compare and calculate brightness values for each unit driving region divided into a plurality, as illustrated in FIGS. 7 and 10. Here, the brightness value may be calculated as a relative ratio (%) with respect to the maximum brightness (that is, the maximum amount of light) of the light emitting device.

For example, in the dual view screen as shown in FIG. 10A, the right display area is displayed as a screen having normal brightness, and the brightness value is calculated as '100%'. The left display area is displayed as a darker screen than the right display area. In this case, the brightness value is less than the maximum light amount (eg, 20%). Here, the brightness value of '100%' means that the unit light emitter, that is, the light emitting device is turned on at the maximum amount of light.

For reference, the brightness value of each display area (ie, the unit driving area) may be calculated by analyzing an image data signal by an image analyzer, the image analyzer may be provided in a controller, and the controller may be a CPU or MCU. Can be configured.

As such, when the brightness value of each region of the display image is calculated, the backlight unit 140 is controlled to calculate the power value to be applied to each unit light emitter.

For example, when image data is input, the brightness values are compared and calculated for each unit driving region. In the example of FIG. 10 (a), the unit driving regions corresponding to ③, ④, ⑦, and ⑧ of FIG. The value is 100%, and the unit driving area corresponding to 1, 2, 5, and 6 may have a brightness value of 20%.

The brightness value of each unit driving region calculated as described above is converted into a power value of the corresponding unit driving region. Here, the "power value of the unit driving region" means a power value to be applied to the unit light emitting body in charge of the corresponding unit driving region in order to implement the brightness value calculated through image data analysis.

When the power value for each unit driving region is calculated through the above process, the controller is configured to implement local dimming by individually controlling each unit light emitter according to the power value.

For example, in the case of FIGS. 10A and 10B, the maximum power for the maximum amount of light (ie, 100% of the brightness value) of the unit light emitter may be defined as 0.21 mW (10.5v, 20mA), in which case, ③ 0.21mW of power is supplied to each unit illuminant in the unit driving regions of ④, ⑦, and ⑧, and 0.042 (0.21mW × 20%) to each unit illuminant in the unit driving regions of ①, ②, ⑤ and ⑥. By controlling the power supply of mW, it is possible to implement divided driving, that is, local dimming.

By the configuration as described above, it is possible to implement a more detailed and precise local dimming compared to the conventional dimming, thereby further reducing the power consumption by 5 to 20%, and further improve the brightness, contrast ratio, visibility, etc. It became.

By the way, the backlight unit of the present invention is uniform in the amount of light in a direction away from the light source due to the gradation effect caused by the change in the amount of light, especially when performing partial dimming (e.g., dividing dimming) in which only some of the unit emitters are turned on and other units are not lit. The problem of deterioration may occur.

In order to solve this problem, the backlight unit of the present invention is configured so that the opposite unit light emitter opposite to the light unit light emitter also emits weak light to compensate for the change in the amount of light of the light unit light emitter.

In detail, the controller of the backlight unit includes a unit driving region corresponding to the brightness value '0' (hereinafter, referred to as a 'black region') among brightness values calculated by analyzing brightness values of unit driving regions of the input image data. At the same time, when the brightness value corresponding to another unit driving region (hereinafter, referred to as a “lighting region”) positioned vertically above or below the black region is greater than at least “0”, the unit light emitter may be defined as follows. Configured to control.

That is, when the condition is satisfied, the control unit is configured to apply power for turning on the first light amount to the first unit light emitter (or the second unit light emitter) in charge of the lighting area, and to display the second unit light emitter in charge of the black area ( Alternatively, the first unit light emitter controls to apply power for turning on the second light amount less than the first light amount.

For example, with reference to FIG. 7, the brightness value of the image corresponding to the second unit driving region ② is '0' (that is, a black image) and is positioned on the vertical upper portion of the second unit driving region ②. Assume that the brightness value of the image corresponding to the 6 unit driving region ⑥ is '100' (that is, the display image).

In this case, the second unit light emitter 23b that is in charge of the sixth unit driving area ⑥ is supplied with power for the first light amount corresponding to the brightness value '100', and is in charge of the second unit driving area ②. The first unit light emitter 21b is applied with power so as to emit less light than the first light amount.

As described above, when dimming an image having a black region into two divisions, the unit illuminant in charge of the unit driving region corresponding to the black image is also controlled to be lit with a relatively small amount of light, thereby correcting light quantity non-uniformity due to lighting of some screens. I can do it.

11 is a view schematically showing an embodiment of a backlight unit according to the present invention. As shown in FIG. 11, one embodiment of a backlight unit according to the present invention includes a light guide plate body 10, a light source unit including a first array 20 and a second array 22, a driver 60, and a controller ( 70).

As described above, the light guide plate body 10 is divided into a plurality of unit driving regions. In the embodiment of FIG. 11, the unit driving regions are divided into a total of eight unit driving regions ① to ⑧, but the number of unit driving regions may be adjusted as necessary.

The light source unit includes a first array 20 and a second array 22, and each of the first array 20 and the second array 22 includes a plurality of unit light emitters 20a to 20d and 22a to 22d, respectively. Include.

In the embodiment of FIG. 11, the light source unit includes a first array 20 and a second array 22, and the first array 20 includes four first unit emitters 20a, 20b, 20c, and 20d. Each of the first unit light emitters 20a, 20b, 20c, and 20d includes a plurality of light emitting devices. The second array 22 includes four second unit emitters 22a, 22b, 22c, and 22d, and each of the second unit emitters 22a, 22b, 22c, and 22d includes a plurality of light emitting devices. . The first unit light emitter and the second unit light emitter correspond to the plurality of unit driving regions in one-to-one correspondence.

The driver 60 controls the brightness of each of the first unit light emitters 20a, 20b, 20c and 20d and the second unit light emitters 22a, 22b, 22c and 22d. The driver 60 supplies power to each of the first unit light emitters 20a, 20b, 20c, and 20d and the second unit light emitters 22a, 22b, 22c, and 22d according to the control signal received from the controller 70. Adjust the brightness of each unit illuminant.

According to an embodiment, the controller 70 includes a receiver, an analyzer, and a signal generator. The receiver receives an image data signal to be displayed on the display unit.

The analysis unit analyzes the image data signal by frame unit for each unit driving region (① to ⑧), compares the luminance value of each pixel in the corresponding frame for each unit driving region (① to ⑧), and compares the luminance of the pixel having the highest luminance. The position and the luminance value of the pixel are calculated as the reference value of the unit driving area.

12 is a diagram illustrating reference values for respective unit driving regions. As shown in FIG. 12, the reference value may be represented by an X, Y coordinate value and a luminance value of the pixel. In the example of FIG. 12, the right two unit driving regions ④ and ⑧ are unlit regions, and the luminance values of the pixels (x4 and y4) of the first unit driving region ① in the lower row are the brightest at 100.

The signal generator generates a control signal through reference values for each unit driving area (① ~ ⑧).

The control signal can be generated by directly using the reference value of each unit driving region. That is, control to adjust the power applied to the first unit light emitters 20a, 20b, 20c, and 20d and the second unit light emitters 22a, 22b, 22c, and 22d so that the pixel of the reference value has a corresponding luminance value. You can generate a signal.

In order to further reduce power consumption, a signal generator including a memory unit, a reference region selector, a first control signal generator, and a second control signal generator may be used to generate a control signal in the following manner. It may be.

First, when each of the first unit light emitters 20a, 20b, 20c, and 20d and the second unit light emitters 22a, 22b, 22c, and 22d is driven, luminance of each position of the light guide plate main body 10 is applied to each unit light emitter. Measure or simulate by varying the amount of power applied. The measurement or simulation information is stored in a memory unit or in a table in the form of a contour graph as shown in FIG. 13.

Since the light guide plate body 10 is not divided into several pieces, when the light emitting element belonging to any one unit light emitter is turned on, the unit driving region of the light guide plate body 10 is brightened. Referring to FIGS. 11 and 13, when the first unit light emitter 20a at the lower left is driven, the lower left near the first unit light emitter 20a is the brightest and becomes darker as it is farther away.

The reference region selector sets one of the plurality of unit driving regions ① to ⑧ as the reference unit driving region. The controller generates a control signal of the corresponding unit light emitter according to the reference value of the unit driving region analyzed by the analyzer.

That is, the first control signal generator generates the first or second unit light emitter control signal so that the pixel having the highest luminance in the reference unit driving region has the corresponding luminance value. As the reference unit driving region, a unit driving region including a pixel having the largest luminance value may be selected.

Next, the second control signal generator generates a control signal of the first or second unit light emitter corresponding to the unit driving regions disposed around the reference unit driving region. In detail, the second control signal generator subtracts the luminance value of the corresponding pixel due to the light emission of the unit emitter corresponding to the reference unit driving region from the luminance value of the pixel having the highest luminance of the unit driving region around the reference unit driving region. The control signal for driving the first or second unit light emitting body corresponding to the corresponding unit driving region is generated based on the difference by the subtraction, that is, the remaining value.

11, 12, and 14, when the first unit light emitter 20a corresponding to the luminance of the (x4, y4) pixel, which is the reference pixel of the reference unit driving region ① on the lower left, becomes 100, is driven. The luminance of the pixels (x1, y1), which are the reference pixels of the unit driving region ⑤ in the upper left corner, is about 60.

Therefore, in order to make the luminance of the (x1, y1) pixel become the reference value of 80, the luminance applied to the (x1, y1) pixel by driving the second unit light emitter 22a corresponding to the unit driving region (⑤) in the upper left corner. It is sufficient to drive the second unit light emitter 22a so that is approximately 20.

Since the (x5, y5) pixels, which are the reference pixels of the unit driving region ② adjacent to the right side of the reference unit driving region ①, have a luminance of about 65 by turning on the reference unit driving region ①, the luminance It has a brightness over 30 which is the reference value of.

Therefore, it is not necessary to apply power to the first unit light emitting body 20b corresponding to the unit driving region ②.

In some cases, the control signals of the first or second unit light emitters corresponding to the unit driving regions spaced one space from the reference unit driving region may be generated in the same manner. In this case, the control signal is generated in consideration of the luminance value caused by the lighting of the adjacent unit driving region instead of the reference unit driving region. Also, the pixel of the reference unit driving region may be brightened by the lighting of the peripheral unit driving region.

On the other hand, the backlight unit of the present invention may cause a problem that the light quantity uniformity may be lowered due to the gradation effect caused by the light quantity change, particularly when dividing dimming is performed in which only some unit light emitters are turned on and other unit light emitters are not lit. .

In order to solve this problem, the backlight unit of the present invention is configured such that the opposite unit light emitter facing the light unit light emitter also lights up a relatively small amount of light so as to correct luminance uniformity for image display.

Specifically, as a result of analyzing the image data signal, there is a unit driving region (hereinafter referred to as a “black region”) corresponding to the pixel brightness '0' and at the same time, another unit located vertically above or below the black region. When the pixel brightness corresponding to the driving area (hereinafter, referred to as a "lighting area") is greater than at least "0", the backlight unit of the present invention is configured to control as follows.

That is, when the condition is satisfied, the backlight unit of the present invention is applied to the unit light emitter in charge of the lighting area for the first light amount is turned on, the unit light emitter in charge of the black area is less than the first light amount It is controlled so that electric power for turning on the second light amount is applied.

While the preferred embodiments of the present invention have been described and illustrated using specific terms, such terms are only for clarity of the present invention, and the embodiments and the described terms of the present invention are defined and the technical spirit and scope of the following claims. It is obvious that various changes and changes can be made without departing from the scope. Such modified embodiments should not be understood individually from the spirit and scope of the present invention, but should fall within the claims of the present invention.

Claims (19)

1. A light source unit; And a light guide plate unit through which light is incident from the light source unit.

   The light guide plate portion,

   A light guide plate body; A first light incident part formed at one side of the light guide plate body to receive light; And a second light incident part formed on the other side surface portion of the light guide plate body to which light is incident.

   The light source unit,

   A first array consisting of a plurality of light emitting elements and disposed on the first light incident part side; And a second array including a plurality of light emitting elements and disposed on the second light incident part side.
2. According to claim 1,

   Each of the first light incident portion and the second light incident portion includes a serration pattern formed in a sawtooth shape,

   The backlight unit,

   The separation distance L1 between the light emitting screen L / A of the light guide plate body and the light emitting devices of the first array is less than 3.2 mm,

   The separation distance L2 between the light emitting screen L / A of the light guide plate body and the light emitting devices of the second array is less than 3.2 mm,

   The serration pattern is

   The pitch unit P1 of the tooth is formed to 0.06 mm or less.
3. The method of claim 2,

   The separation distance (L1, L2) is formed to 1.35mm,

   Backlight unit, characterized in that the pitch (P1) of the tooth is formed to 0.04mm.
4. The method of claim 2,

   The first array is composed of N light emitting elements, and the N light emitting elements are configured to form N / M (where N ≧ M) first unit light emitters, grouped by M units,

   The second array is composed of N 'light emitting elements, and the N' light emitting elements are grouped by M 'units to form N' / M '(here, N'≥M') second unit light emitters. ,

   The N / M first unit light emitters are configured to be individually controlled, and a lower region of the light guide plate main body is divided into N / M driving regions by the N / M first unit light emitters,

   The N '/ M' second unit light emitters are configured to be individually controlled, and the upper region of the light guide plate body is N '/ M' drive area by the N '/ M' second unit light emitters. Divided into

   The backlight unit is configured to have a driving region (hereinafter referred to as a 'unit driving region') divided into a total of N / M + N '/ M' pieces.
5. The method of claim 4, wherein

   A control unit for analyzing input image data and controlling driving of the first unit light emitter and the second unit light emitter;

   The control unit,

   A first function of calculating brightness values of the unit driving regions based on input image data;

   A second function of converting the brightness value calculated by the first function into a power value to be applied to the first unit light emitting body or the second unit light emitting body in charge of the corresponding unit driving region; And

   And a third function of controlling the amount of light of the first unit light emitter or the second unit light emitter according to the power value derived by the second function.
6. The method of claim 5,

   The control unit,

   There is a unit driving region (hereinafter referred to as a 'black region') in which the brightness value calculated by the first function corresponds to '0', and another unit located at the top or bottom of the black region at the same time. When the brightness value corresponding to the driving area (hereinafter, referred to as 'lighting area') is greater than at least '0',

   The first unit emitter or the second unit emitter in charge of the lighting area is supplied with power for turning on a first light amount, and the second unit emitter or first unit emitter in charge of the black area is less than the first light amount. And a fourth function of controlling to apply power for turning on the second light amount.
7. The method of claim 5,

   And the brightness value is calculated as a relative ratio (%) to the maximum amount of light of the light emitting device.
8. The method of claim 2,

   Further comprising a light scattering pattern formed in an intaglio or embossed form on the upper or lower surface of the light guide plate body,

   And the light scattering pattern is densely arranged closer to the center of the light guide plate.
9. The method of claim 2,

   The serration pattern is a backlight unit, characterized in that the angle (θ1) between the neighboring teeth is configured to form a 85 ° ~ 95 °.
10. The method of claim 2,

    And the first light incident portion and the second light incident portion are integrally formed with the light guide plate body or separately formed and formed in the form of a lens disposed adjacent to both sides of the light guide plate body.
11. According to claim 1,

    The light guide plate main body includes a unit driving region in which a lighting region is divided into a plurality, and each of the first array and the second array includes a plurality of unit light emitters, and each of the unit light emitters respectively corresponds to the unit driving area. ,

    A driver configured to adjust brightness of the plurality of light emitters, respectively; And receiving an image data signal, analyzing the image data signal for each unit driving region, finding the brightest reference pixel for each unit driving region, and determining a reference value for each unit driving region based on the position and brightness of the reference pixel. And a control unit which generates a control signal according to the determined reference value for each unit driving region and transmits the control signal to the driving unit.
12. The method of claim 11, wherein

    The control unit,

    A receiver for receiving an image data signal;

    An analysis unit which analyzes the image data signal for each unit driving region, finds the brightest reference pixel for each unit driving region, and determines a reference value for each unit driving region based on the position and brightness of the reference pixel; And

    And a signal generator configured to generate a control signal according to the determined reference value for each unit driving region.
13. The method of claim 12,

    The signal generation unit,

    A memory unit in which luminance of each position of the entire light guide plate is stored according to a change in the size of power applied to each unit light emitter;

    A reference region selection unit to select a reference unit driving region;

    A first control signal generator configured to generate a driving control signal of a unit light emitter corresponding to the reference pixel having the highest luminance in the reference unit driving region to have a corresponding luminance value; And

    Based on the luminance value of the reference pixel having the highest luminance of the unit driving region around the reference unit driving region, the unit is calculated based on the remaining value obtained by subtracting the luminance value of the pixel corresponding to the emission of the unit light emitting body corresponding to the reference unit driving region. And a second control signal generator configured to generate a driving control signal of the unit light emitter corresponding to the driving region.
14. The method of claim 13,

    And the reference region selector selects the unit driving region including the pixel having the largest luminance value as the reference unit driving region.
15. A liquid crystal display panel comprising a pair of substrates disposed to face each other and a liquid crystal layer interposed between the pair of substrates; And a backlight unit selected from any one of claims 1 to 13.
16. A light guide plate portion including a light guide plate body, a first light incident portion formed at one side of the light guide plate body to receive light, and a second light incident portion formed at the other side portion of the light guide plate body to receive light; And a light source unit including a first array consisting of a plurality of light emitting elements and disposed on the first light incident part side, and a second array made of another plurality of light emitting elements and disposed on the second light incident part side; The light guide plate main body includes a unit driving region in which a lighting region is divided into a plurality, and the first array and the second array each include a plurality of unit emitters, and each of the unit emitters corresponds to the unit driving region, respectively. As a dimming method of a backlight unit,

    Receiving an image data signal;

    Analyzing the image data signal for each unit driving region to find the brightest reference pixel for each unit driving region;

    Determining a reference value for each unit driving region based on the position and brightness of the brightest reference pixel; And

    And controlling unit light emitters corresponding to each of the unit driving regions according to the determined reference value for each of the unit driving regions.
17. The method of claim 16,

    Controlling the respective unit light emitters,

    Determining a reference unit driving region;

    Generating a driving control signal of a unit light emitter corresponding to the reference pixel having the highest luminance in the reference unit driving region to have a corresponding luminance value; And

    The unit driving is performed based on the luminance value of the reference pixel having the highest luminance of the unit driving region around the reference unit driving region minus the luminance value of the pixel corresponding to the emission of the unit light emitting body corresponding to the reference unit driving region. And generating a driving control signal of the unit light emitter corresponding to the region.
18. The method of claim 17,

    The determining of the reference unit driving region may include determining a unit driving region including a reference pixel having the highest luminance as the reference unit driving region.
19. The method of claim 16,

    As a result of analyzing the image data signal, there is a unit driving region corresponding to pixel brightness '0' (hereinafter referred to as 'black region'), and at the same time, another unit driving region positioned vertically above or below the black region. If the pixel brightness corresponding to (hereinafter referred to as 'lighting area') is greater than at least '0',

    Controlling the unit light emitter in charge of the lighting area to receive power for turning on a first light amount, and the unit light emitter in charge of the black area applying power for turning on the second light amount less than the first light amount. The backlight unit dimming method further comprises.

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