Patent Publication Number: US-2013250606-A1

Title: Backlight module and liquid crystal display

Description:
FIELD OF THE INVENTION 
     The present invention relates to a field of liquid crystal display technology, and more particularly to a backlight module and a liquid crystal display (LCD). 
     BACKGROUND OF THE INVENTION 
     With the continuous development of liquid crystal technology, the requirement for the internal components of a liquid crystal display (LCD) is higher and higher. 
     Referring now to  FIG. 1 , a structural schematic view of a backlight module in a traditional technology is illustrated in  FIG. 1 . 
     A backlight module comprises a light source  11  and a light guide plate  12 , wherein the light guide plate  12  comprises a light in surface  121  and a light out surface  122 . A lights emitted from the light source  11  are through the light in surface  121  of the light guide plate  12  entering into the light guide plate  12 , and are emitted out of the light out surface  122  of the light guide plate  12  by reflecting of the light guide plate  12 . 
     To prevent the lights from producing a total internal reflection when they are through the light out surface  122 , the traditional technology is generally provided with a plurality of micro structures  123  on the light out surface  122  of the light guide plate  12 , and the micro structures  123  can prevent the lights from producing a total internal reflection on the light out surface  122 . 
     Referring now to  FIG. 2 , a side view of the backlight module in  FIG. 1  is illustrated in  FIG. 2 . 
     A Light in direction “A” is along a direction which is from the light source  11  and perpendicularly enters into the light guide plate  12 . Along the Light in direction “A”, and with the increasing of distance between the micro structures  123  and the light source  11 , pitches P′i between the adjoining micro structures  123  are gradually decrease, so that it can make the lights entering into the light guide plate  12  are uniformly emitted out, so as to avoid a phenomenon of “Mura”. 
     However, with the increasing of requirement of the LCD size, the size of the backlight module is correspondingly increased, so that it is necessary to need a light guide plate  12  with bigger size. While the size of the light guide plate  12  is increased, the transmission distances of the lights in the light guide plate  12  are increased. Along the direction “A”, the pitches P′i between the adjoining micro structures  123  are also smaller and smaller. Because the limit of manufacture technology, the pitches P′i between the adjoining micro structures  123  has a minimum value, such as 50 μm. When the pitches P′i are smaller than 50 μm, the adjoining micro structures  123  can not be smaller any more, and the adjoining micro structures  123  are only arranged by 50 μm, uniformly, so that the lights can not be uniformly emitted out, and then cause the “Mura” phenomenon. 
     Besides, if the pitch P′i is too small, such as smaller than the width of the micro structures  123 , it will cause the interference between the micro structures  123 , so as to influence the light out effect of the backlight module, and further influence the display quality of the LCD image. 
     As described above, how to solve the technologic problem influencing the image display effect, which is that the micro structures  123  of the light out surface  122  of the light guide plate  12  can not be smaller without limit causing the lights can not be uniformly emitted out of the light out surface  122  of the light guide plate  12 , is become one of the research directions of the field of liquid crystal manufacture technologies. 
     SUMMARY OF THE INVENTION 
     One of the objects of the present invention is to provide a backlight module to solve the technology problem influencing the image display effect, which is that the micro structures of the light out surface of the light guide plate can not be smaller without limit causing the lights can not be uniformly emitted out of the light out surface of the light guide plate. 
     For solving the above-mentioned technology problem, the present invention is provided with a backlight module, which comprises at least one light source and a light guide plate, wherein the light guide plate comprises a light out surface and a light in surface disposed on at least one side of the light out surface; the light source is closer to the light in surface, and the light out surface is provided with a plurality of strip-shaped micro structures; 
     wherein a light in direction is a direction which is perpendicular with the light in surface; a longitude direction of the micro structures is parallel with a horizontal plane of the light out surface of the light guide plate, and is perpendicular with the light in direction; each of the micro structures comprises a first light out surface and a second light out surface, which extend along the longitude direction and correspondingly incline to each other; the first light out surface has a first oblique angle with a horizontal plane of the light guide plate; the second light out surface has a second oblique angle with the horizontal plane of the light guide plate; and the oblique direction of the first oblique angle and the second oblique angle are opposite to each other; and 
     wherein with the distance increasing along the light in direction, the first oblique angle gradually decreases to a first low value, and then gradually increases to a first high value, so that the lights can be uniformly emitted out through the micro structures; and the first oblique angle is smaller than 25 degree. 
     In the backlight module of the present invention, with the distance increasing along the light in direction, the second oblique angle is gradually increases to a second high value, and then gradually decreases to a second low value. 
     In the backlight module of the present invention, the micro structures has a protrude height from the horizontal plane of the light guide plate; the protrude height of the micro structures has a variation trend as shown in follows: along the perpendicular direction, the height of the micro structures gradually increases to a first high value, and then gradually decreases to a first low value. 
     In the backlight module of the present invention, along the light in direction and with increasing of distance from the light source, the first oblique angles are changed, but the second oblique angles are fixed. 
     In the backlight module of the present invention, the first oblique angle is smaller than 25 degree. 
     Another one of the objects of the present invention is to provide a backlight module to solve the technology problem influencing the image display effect, which is the micro structures of the light out surface of the light guide plate can not be smaller without limit causing the light can not be uniformly emitted out of the light out surface of the light guide plate. 
     For solving the above-mentioned technology problem, the present invention is provided with a backlight module, which comprises at least one light source and a light guide plate, wherein the light guide plate comprises a light out surface and a light in surface disposed on at least one side of the light out surface; the light source is closer to the light in surface, and the light out surface is provided with a plurality of strip-shaped micro structures; 
     wherein a light in direction is a direction which is perpendicular with the light in surface; a longitude direction of the micro structures is parallel with a horizontal plane of the light out surface of the light guide plate, and is perpendicular with the light in direction; each of the micro structures comprises a first light out surface and a second light out surface, which extend along the longitude direction and correspondingly incline to each other; the first light out surface has a first oblique angle with a horizontal plane of the light guide plate; the second light out surface has a second oblique angle with the horizontal plane of the light guide plate; and the oblique direction of the first oblique angle and the second oblique angle are opposite to each other; and 
     wherein along the light in direction, one of the first oblique angle or the second oblique angle is changed with the distance increasing of the light source, so that the lights can be uniformly emitted out through the micro structures. 
     In the backlight module of the present invention, with the distance increasing along the light in direction, the first oblique angle is gradually decreases to a first low value, and then gradually increases to a first high value; and the second oblique angle is gradually increases to a second high value, and then gradually decreases to a second low value. 
     In the backlight module of the present invention, the micro structures has a protrude height from the horizontal plane of the light guide plate; the protrude height of the micro structures has a variation trend as shown in follows: along the perpendicular direction, the height of the micro structures gradually increases to a first high value, and then gradually decreases to a first low value. 
     In the backlight module of the present invention, along the light in direction and with increasing of distance from the light source, the first oblique angles are changed, but the second oblique angles are fixed. 
     In the backlight module of the present invention, along the light in direction and with increasing of distance from the light source, the second oblique angles are changed, but the first oblique angles are fixed. 
     In the backlight module of the present invention, the first oblique angle and the second oblique angle are both smaller than 25 degree. 
     Further, another one of the objects of the present invention is to provide a liquid crystal display (LCD) to solve the technology problem influencing the image display effect, which is the micro structures of the light out surface of the light guide plate can not be smaller without limit causing the light can not be uniformly emitted out of the light out surface of the light guide plate. 
     For solving the above-mentioned technology problem, the present invention is provided with an LCD comprising a backlight module, wherein the backlight module comprises at least one light source and a light guide plate; the light guide plate comprises a light out surface and a light in surface disposed on at least one side of the light out surface; the light source is closer to the light in surface, and the light out surface is provided with a plurality of strip-shaped micro structures; 
     wherein a light in direction is a direction which is perpendicular with the light in surface; a longitude direction of the micro structures is parallel with a horizontal plane of the light out surface of the light guide plate, and is perpendicular with the light in direction; each of the micro structures comprises a first light out surface and a second light out surface, which extend along the longitude direction and correspondingly incline to each other; the first light out surface has a first oblique angle with a horizontal plane of the light guide plate; the second light out surface has a second oblique angle with the horizontal plane of the light guide plate; and the oblique direction of the first oblique angle and the second oblique angle are opposite to each other; and 
     wherein along the light in direction, one of the first oblique angle or the second oblique angle is changed with the distance increasing of the light source, so that the lights can be uniformly emitted out through the micro structures. 
     In the LCD of the present invention, with the distance increasing along the light in direction, the first oblique angle is gradually decreases to a first low value, and then gradually increases to a first high value; and the second oblique angle is gradually increases to a second high value, and then gradually decreases to a second low value. 
     In the LCD of the present invention, the micro structures has a protrude height from the horizontal plane of the light guide plate; the protrude height of the micro structures has a variation trend as shown in follows: along the perpendicular direction, the height of the micro structures gradually increases to a first high value, and then gradually decreases to a first low value. 
     In the LCD of the present invention, along the light in direction and with increasing of distance from the light source, the first oblique angles are changed, but the second oblique angles are fixed. 
     In the LCD of the present invention, along the light in direction and with increasing of distance from the light source, the second oblique angles are changed, but the first oblique angles are fixed. 
     In the LCD of the present invention, the first oblique angle and the second oblique angle are both smaller than 25 degree. 
     In comparison with the traditional technologies, in the present invention, by fixed the width and pitch of the micro structure, along the light in direction which is perpendicular with light in surface and according to the different distance from the light source, it can changes at least one of the first oblique angle and second oblique angle, so that the lights can be uniformly emitted out of the light out surface. It is unnecessary to change the pitch of the micro structures, and can make the lights are uniformly emitted out of the light out surface, so as to increase the display quality of image. 
     For above-mention contents of the present invention can be best understood by referring to the following detailed description of the preferred embodiments and the accompanying drawings. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a structural schematic view of a backlight module in a traditional technology; 
         FIG. 2  is a side view of the backlight module in  FIG. 1 ; 
         FIG. 3  is a structural schematic view of a backlight module of a first preferred embodiment according to the present invention; 
         FIG. 4  is a side view of the light guide plate in  FIG. 3 ; 
         FIG. 5  is a variation trend schematic view of the first oblique angle of the micro structures; 
         FIG. 6  is a variation trend schematic view of the second oblique angle of the micro structures; and 
         FIG. 7  is a variation trend schematic view of the protrude height of the micro structures. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The description of the preferred embodiments refers to the drawings, so as to illustrate the specific embodiments of the present invention which can be carried out. 
     Referring now to  FIG. 3 , a structural schematic view of a backlight module of a first preferred embodiment according to the present invention is illustrated in  FIG. 3 . 
     A backlight module comprises at least one light source  10  and a light guide plate  20 , wherein the light guide plate  20  comprises a light out surface  21  and a light in surface  22  disposed on at least one side of the light out surface  21 , and the light source  10  is closer to the light in surface  22 . While the embodiment is in operation, the lights emitted from the light source  10  are through the light in surface  22  entering into the light guide plate  20 , and are emitted out of the light out surface  21  by reflecting of the light guide plate  20 . 
     Referring to  FIG. 4 , a side view of the light guide plate in  FIG. 3  is illustrated in  FIG. 4 . 
     The light out surface  21  is provided with a plurality of strip-shaped micro structures  23 , wherein the micro structures  23  have the same pitches therebetween and the same widths W. 
     A light in direction “B” is a direction which is perpendicular with the light in surface  22 . A longitude direction “C” of the micro structures  23  is parallel with a horizontal plane “D” of the light out surface  21  of the light guide plate  20 , and is perpendicular with the light in direction “B”. Besides, each of the micro structures  23  extends along the longitude direction “C”, and has corresponding inclined planes. 
     The micro structure  23  comprises a first light out surface  231  and a second light out surface  232 . There is a first oblique angle δi between Each of the first light out surface  231  of the micro structures  23  and the horizontal plane “D” of the light guide plate  20  (i is a natural number); and there is a second oblique angle θi between Each of the second light out surface  232  of the micro structures  23  and the horizontal plane “D” of the light guide plate  20  (i is a natural number). For example, along the light in direction “B”, one of the micro structures  23 , which is the closest one to the light source  10  has a first oblique angle δ 1  and a second oblique angle θ 1 ; the next micro structure  23  has a first oblique angle δ 2  and a second oblique angle θ 2 ; and then the others are by analogy. 
     The oblique direction of the first oblique angle δi and the second oblique angle θi are opposite to each other. Specifically speaking, the first oblique angle δi is rotated in clockwise direction, and the second oblique angle θi is rotated in counter clockwise direction. 
     In this embodiment, along the light in direction “B”, at least one of the first oblique angle δi and the second oblique angle θi is changed with the distance increasing from the light source  10 , so that the lights can be uniformly emitted out through the micro structures  23 . 
     For example, please refer  FIGS. 5 and 6 . 
       FIG. 5  is a variation trend schematic view of the first oblique angle δi of the micro structures  23  along the light in direction “B”, wherein X-axis means the distance from the light source  10 , and the Y-axis means the first oblique angle δi. With the distance increasing along the light in direction “B”, the value of the first oblique angle δi is from a first start point value “a” gradually decreases to a first low value “b”, and then gradually increases to a first high value “c”. For example, the first oblique angle δ 2  is larger than the first oblique angle δ 1 ; and the first oblique angle δ 5  is larger than the first oblique angle δ 2 . 
     A variation relation equation of the first oblique angle δi is as follow: 
       δ( x )=3.8621343+1.6164448 ·x+ 5.0190765 ·x 2+1.3845206 ·x 3
 
     (in this equation, X means the distance from the light source  10 ) 
       FIG. 6  is a variation trend schematic view of the second oblique angle θi of the micro structures  23  along the light in direction “B”, wherein X-axis means the distance from the light source  10 , and the Y-axis means the second oblique angle θi. A variation relation equation of the second oblique angle θi is as follow: 
       θ( x )=10.021987+4.9999959 ·x− 4.807639 ·x 2−2.6291689 ·x 3;
 
     (in this equation, X means the distance from the light source  10 ) 
     With the distance increasing along the light in direction “B”, the value of the second oblique angle θi is from second start point value “d” gradually increases to a second high value “e”, and then gradually decreases to a second low value “f”. For example, the second oblique angle θ 2  is larger than the second oblique angle θ 1 ; and the second oblique angle θ 5  is larger than the second oblique angle θ 2 . 
     While the embodiment is in operation, the first oblique angle δi and the second oblique angle θi are both smaller than 25 degree. 
     Referring to  FIG. 4 , the micro structure  23  has a protrude height Hi from the horizontal plane “D” of the light guide plate  20 . For example, one of the micro structures  23  which is the closest one to the light source  10  has a protrude height H 1 ; the next one has a protrude height H 2 ; and then the others are by analogy. 
     Referring to  FIG. 7 ,  FIG. 7  is a variation trend schematic view of the protrude height of the micro structures  23  along the light in direction “B”. The protrude height Hi of the micro structures  23  has a variation trend as shown in follows: along the light in direction “B”, the value of the protrude height Hi of the micro structures  23  is from a third start point value “g” gradually increases to a first high value “h”, and then gradually decreases to a first low value “j”. Certainly, the variation trend of the protrude height Hi of the micro structures  23  is base on the fixed pitches between the micro structures  23 . 
     The pitch P between the micro structures  23  and the width of the micro structures  23  are fixed; the first oblique angle θi of the micro structures  23  have a variation trend as shown in  FIG. 5 ; and the second oblique angle δi of the micro structures  23  have a variation trend as shown in  FIG. 6 . Hence, the protrude height Hi of the micro structures  23  has a variation trend as shown in  FIG. 7 . Because the protrude heights Hi of the micro structures  23  according to the present invention have a variation trend as shown in  FIG. 6 , the heights of the entire micro structures  23  of the light guide plate  20  are lower, so as to decrease the entire thickness of light guide plate  20 , so that it can decrease the used quantity of material, and lower the manufacture cost. 
     As shown in  FIGS. 3 to 7 , the working principle of the first preferred embodiment of the backlight module is described as follow: 
     For example, the pitch P of the micro structures  23  is 150 mm, and the width W thereof is 50 mm. The first oblique angle ei of the micro structures  23  have a variation trend as shown in  FIG. 4 ; and the second oblique angle δi of the micro structures  23  have a variation trend as shown in  FIG. 5 . 
     In the above-mentioned variation trends, along the light in direction “B”, the lights enter into the light guide plate  20 , and are emitted out of the light out surface  21  by the reflecting of the light guide plate  20 . Besides, along the light in direction “B”, the light-near-end portion of the light out surface  21  which is closer to the light source  10  gets the more illumination by the deflection light of the light source  10 , and then it is decreased by the increasing of the distance. Hence, the value of the first oblique angle ei is from first start point value “a” gradually decreases to a first low value “b”. 
     In the light-far-end portion of the light out surface  21  which is the farther from the light source  10  is influenced by the reflection of the end of the light guide plate  20 , so it can gets the more illumination by the deflection light of the light source  10 , so that the value of the first oblique angle θi is from first low value “b” gradually increases to a first high value “c”. By above-mentioned arrangement, it makes the first light out surfaces  231  can get and reflect the lights, so that the lights can be uniformly emitted out of the light out surface  21 . 
     The second light out surface  232  and the second oblique angle δi have the similar principle, so do not describe again. 
     As a second preferred embodiment of the present invention, the second oblique angle δi is a fixed value, and then along the light in direction “B” and with increasing of distance from the light source  10 , the first oblique angles θi are changed, so that the lights can be uniformly emitted out of the light out surface  21 . 
     As a third preferred embodiment of the present invention, the first oblique angle θi is a fixed value, and then along the light in direction “B” and with increasing of distance from the light source  10 , the second oblique angles δi are changed, so that the lights can be uniformly emitted out of the light out surface  21 . 
     The working principles of the second and third preferred embodiment are similar to the first preferred embodiment, so do not describe again. 
     The present invention also provides a liquid crystal display (LCD), the LCD comprises the backlight module of the present invention. According to the detail description in above text, so do not describe again. 
     In the present invention, by fixed the width and pitch of the micro structure, along the light in direction which is perpendicular with light in surface and according to the different distance from the light source, it can changes at least one of the first oblique angle and second oblique angle, so that the lights can be uniformly emitted out of the light out surface. It is unnecessary to change the pitch of the micro structures, and can make the lights are uniformly emitted out of the light out surface, so as to increase the display quality of image. 
     As described above, the present invention has been described with a preferred embodiment thereof and it is understood that many changes and modifications to the described embodiment can be carried out without departing from the scope and the spirit of the invention that is intended to be limited only by the appended claims.