WO2013145978A1

WO2013145978A1 - Light source module and liquid crystal display device

Info

Publication number: WO2013145978A1
Application number: PCT/JP2013/054477
Authority: WO
Inventors: 花野　雅昭; 和也生田; 栗本　英治; 翔太井上; 秀明名倉
Original assignee: シャープ株式会社
Priority date: 2012-03-30
Filing date: 2013-02-22
Publication date: 2013-10-03
Also published as: JP2013211215A

Abstract

Provided are a light source module and liquid crystal display device that, in a case where the emission surface has a cross-sectional shape, suppress light leak occurring at the edges and enable luminance distribution to be nonuniform. The light source module is provided with the following: a light guide plate for emitting from an emission surface light incident on an end surface in an orthogonal direction from at least one of a pair of opposing end surfaces; a plurality of LEDs (12) for projecting light onto the light guide plate; and a plurality of light path changing units for extracting light guided inside the light guide plate to a lower surface opposite the light emission surface of the light guide plate. On the emission surface of the light guide plate, a plurality of stripe-shaped uneven members are formed along the direction orthogonal to the end surface on which light is incident. The distribution of the light volume of the plurality of LEDs (12) is such that the light volume is greater in the center of the end surface on which light is incident than the edges thereof.

Description

Light source module and liquid crystal display device

The present invention relates to a light source module and a liquid crystal display device including a side edge (also referred to as a side light) type light guide plate that emits light from a light source in a planar shape by a light guide plate. The present invention relates to prevention of non-uniform luminance distribution when a light guide plate having a streak-like uneven shape is used.

In recent years, in a liquid crystal display device, in order to reduce the thickness, a backlight having a side edge type light guide plate that emits light from a light source in a planar shape by a light guide plate is frequently used.

As such a side edge type light guide plate, for example, a liquid crystal display device disclosed in Patent Document 1 is known. In the liquid crystal display device 100 of Patent Document 1, as shown in FIGS. 20A and 20B, the light guide 110 has a light diffusion pattern in which a plurality of grooves 111 having a substantially V-shaped cross section are formed on the emission surface. And a light reflection pattern in which a plurality of grooves 112 having a substantially V-shaped cross section are formed along a direction intersecting the traveling direction of the principal ray on the light reflection surface facing the emission surface. As a result, the light introduced into the light guide 110 is repeatedly diffused and reflected by the light diffusion pattern and the light reflection pattern, and a bright display screen in which the brightness balance and the brightness peak are freely adjusted is obtained. Yes.

Further, for example, as shown in FIG. 21, the backlight device 200 disclosed in Patent Document 2 includes light sources 210A and 210B in which a plurality of LED packages 201 are linearly arranged, and one flat surface portion is in the plane. The light guide plate 220 is a reflection surface on which a plurality of reflection portions 221... Are formed, and the other flat surface portion is an emission surface from which light is emitted. The light sources 210A and 210B are arranged along the

side surfaces

222A and 222B along the vertical direction of the light guide plate 220, and the arrangement intervals of the plurality of LED packages 201 of the light sources 210A and 210B are widened toward the upper side in the vertical direction, and reflected. The arrangement | positioning space | interval of the some reflection part 221 of a surface is so narrow that it goes to the upper side of a perpendicular direction.

With this configuration, the backlight device 200 is designed to improve the uniformity of the luminance distribution on the exit surface from which light is emitted in the edge light type backlight device 200.

That is, when the light guide plate 220 is erected in the vertical direction, the temperature on the upper side of the light guide plate 220 is increased due to convection, and the luminance of the light sources 210A and 210B on the upper side of the light guide plate 220 is increased. In this case, the luminance distribution becomes uneven. Therefore, in the backlight device 200, the arrangement pitch of the light sources 210A and 210B is increased toward the upper side of the light guide plate 220.

On the other hand, when the arrangement pitch of the light sources 210 </ b> A and 210 </ b> B is changed in this way, the amount of light emitted from the exit surface of the light guide plate 220 decreases as it goes to the upper side of the light guide plate 220. Therefore, in the backlight device 200, the arrangement interval of the reflecting portions 221 is narrowed toward the upper side in the vertical direction.

JP 2004-037982 A (published on April 05, 2004) JP 2010-282911 A (released on December 16, 2010)

Generally, in a liquid crystal display device, the brightness of the central portion is increased, and the brightness is gradually decreased toward the edge of the screen. That is, it is possible to feel a natural quality by making a mountain-shaped luminance distribution having a peak at the center. This is because a display device using a cathode ray tube has a distribution in which the luminance of the central portion is high, and the viewer is accustomed to the luminance distribution of the cathode ray tube. For this reason, the distribution in which the brightness is high in a strip shape at the center of the screen is uncomfortable and inferior in quality.

By the way, in the light guide 110 having a cross-sectional shape on the exit surface like the liquid crystal display device 100 disclosed in the above-mentioned conventional patent document 1, the straightness of the LED exit light is high, so the direction is parallel to the entrance surface. The spread of light to the can be suppressed.

However, when the LEDs are uniformly arranged, if the pattern density of the optical path changing unit is relatively increased in order to increase the luminance of the central portion of the light guide, light extraction is sufficiently performed in the central region, so that light is incident. Although light leakage at the opposite end face of the surface is small, as shown in FIGS. 9A and 9B, which are explanatory diagrams of the present embodiment, the pattern density of the optical path changing portion is lower in the both end regions than in the central region. For this reason, light extraction is not sufficient and leakage light is generated. As a result, the luminance distribution is disturbed.

In such a case, it is conceivable to change the arrangement pitch of the light sources. However, in the arrangement pitch of the light sources such as the backlight device 200 disclosed in Patent Document 2, the light guide having a cross-sectional shape on the exit surface. Since the body is not used and the problem is different, this problem cannot be solved.

The present invention has been made in view of the above-described conventional problems, and its purpose is to suppress the light leakage occurring at the end portion when the exit surface has a cross-sectional shape, and uneven luminance distribution. It is an object of the present invention to provide a light source module and a liquid crystal display device that can be realized.

In order to solve the above-described problems, the light source module of the present invention includes a light guide plate that emits light incident in a direction perpendicular to the end surface from at least one of a pair of opposed end surfaces, and light that is incident on the light guide plate. A light source module comprising: a plurality of light sources incident on the light guide plate; and a plurality of light path conversion units for extracting light guided inside the light guide plate on a surface opposite to the light exit surface of the light guide plate. In the light guide plate, a plurality of streaky irregularities are formed on a light exit surface of the light guide plate along a direction perpendicular to an end face on which the light is incident. The incident end face is characterized in that the center has a larger amount of light than the end.

According to the above invention, the light source module includes a light guide plate that emits light that has entered in a direction perpendicular to the end surface from at least one of a pair of opposing end surfaces, and a plurality of light that enters the light guide plate. A light source and a plurality of optical path conversion units for extracting light guided inside the light guide plate are provided on a surface of the light guide plate opposite to the light exit surface. A plurality of streak-like irregularities along the direction perpendicular to the end face on which the light is incident are formed on the exit surface of the light guide plate.

Thus, when a plurality of streaky irregularities along the direction perpendicular to the end surface on which light is incident is formed on the exit surface of the light guide plate, the straightness in the emitted light of the light source is high. The spread of light in a direction parallel to the incident surface can be suppressed.

However, when the light sources are uniformly arranged, if the pattern density of the optical path conversion unit is relatively increased in order to increase the luminance of the central portion of the light guide plate, light extraction is sufficiently performed in the central region, so that the light incident surface The light leakage at the opposite end face is small, but the pattern density is lower in the both end regions than in the central region, so that the light extraction is not sufficient and leakage light is generated. As a result, the luminance distribution is disturbed.

Therefore, in the present invention, in the distribution of the light quantity by the plurality of light sources, the light quantity at the center is larger than that at the end part at the end face where the light is incident. As a result, a light quantity distribution by a plurality of light sources is created in a direction parallel to the end face on which light is incident, and a natural luminance distribution can be realized on the exit surface of the light guide plate.

Therefore, when the exit surface has a cross-sectional shape, it is possible to provide a light source module capable of suppressing the light leakage generated at the end portion and making the luminance distribution non-uniform.

In the light source module of the present invention, it is preferable that the arrangement density per unit area in the plurality of light sources provided along the end face of the light guide plate is larger at the center than on the end side.

Thereby, as the light amount distribution adjustment, the arrangement density per unit area in the plurality of light sources is made larger at the center than at the end side. As a result, the luminance on the end side of the light guide plate can be reduced, so that light leakage generated at the end can be suppressed.

In the light source module of the present invention, the luminances emitted from the light sources can be the same.

Thereby, the arrangement density per unit area of the plurality of light sources is made larger at the center than at the end side under the condition that the luminances emitted from the respective light sources are the same.

Therefore, since the brightness of the light source is the same, the brightness on the end side of the light guide plate can be reduced with a simple configuration without controlling the light amount of the light source, and light leakage occurring at the end is suppressed. can do.

In the light source module of the present invention, the arrangement positions of the plurality of light sources provided along the end face of the light guide plate are arranged such that the arrangement pitch of each light source is at least one or more light sources as it moves from the center to the end side. Preferably, it is set to increase stepwise.

Thereby, it is possible to provide a specific arrangement position of a plurality of light sources for reducing the luminance on the end side of the light guide plate.

In the light source module of the present invention, it is preferable that the luminance of each light source is such that the central light source is the largest on the end face where the light is incident, and the light source is lighter on the end side.

This adjusts the light intensity distribution by changing the brightness of the light source. As a result, for example, even when the arrangement pitches of the light sources are equal, by adjusting the luminance of the light sources, the light amount at the center is larger than the end side at the end surface where light enters. A light amount distribution can be obtained.

In the light source module of the present invention, it is preferable that the power input to each light source in the plurality of light sources provided along the end face of the light guide plate is larger in the central light source than in the end light source.

This adjusts the light intensity distribution by adjusting the power input to the light source. As a result, for example, even when the arrangement pitches of the light sources are equal, by adjusting the power input to the light sources, the amount of light at the center is greater than the end side at the end surface where the light is incident. The distribution of the amount of light can be obtained.

In the light source module of the present invention, the position of W (width) / 9 from the center point of the light guide plate and the left and right end portions of the light guide plate at the vertical and horizontal center lines of the light guide plate or the upper and lower end portions 4 points at the position of V (vertical width) / 9 and 4 points at the position of W (horizontal width) / 9 from the left and right ends of the light guide plate and V (vertical width) / 9 from each of the upper and lower ends At least one of the arrangement density of the light sources, the luminance of each light source, and the power of each light source is set so that the ratio of the minimum luminance to the maximum luminance when each of the nine luminances is measured is 50% or more. It is preferable that it is set.

Thereby, it is possible to provide a light source module that can surely make the luminance distribution non-uniform on the exit surface of the light guide plate of the light source module.

In order to solve the above problems, a liquid crystal display device of the present invention is characterized by including the light source module described above.

According to the above invention, a liquid crystal display device provided with a light source module capable of suppressing the light leakage generated at the end and making the luminance distribution non-uniform when the exit surface has a cross-sectional shape is provided. Can do.

As described above, in the light source module of the present invention, a plurality of streak-like uneven shapes along the direction perpendicular to the end surface on which light is incident are formed on the exit surface of the light guide plate. The distribution of the amount of light by means that the amount of light at the center is larger than that at the end of the end surface where light enters.

The liquid crystal display device of the present invention includes the light source module described above as described above.

Therefore, there is an effect of providing a light source module and a liquid crystal display device capable of suppressing the light leakage generated at the end and making the luminance distribution non-uniform when the exit surface has a cross-sectional shape.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates an embodiment of a light source module according to the present invention, and is a diagram illustrating a light amount distribution and LED placement positions. It is a disassembled perspective view which shows the structure of the liquid crystal display device provided with the said light source module. It is principal part sectional drawing which shows the structure of the liquid crystal display device provided with the said light source module. It is a principal part perspective view which fractures | ruptures and shows the structure of the said light source module partially. It is sectional drawing which shows the emitted light from the uneven | corrugated shaped body formed in the output surface of the light-guide plate in the said light source module. (A)-(d) is sectional drawing which shows the various shapes of the uneven | corrugated shaped body formed in the output surface of the light-guide plate in the said light source module. (A) is a top view which shows the breadth of the propagation light in the light-guide plate which consists of flat plates, (b) is a front view which shows the spread of the propagation light in the light-guide plate which consists of flat plates. (A) is a top view which shows the breadth of the propagation light in the light-guide plate which has an uneven | corrugated shaped body, (b) is a front view which shows the spread of the propagation light in the light guide plate which has an uneven | corrugated shaped body. (A) is a top view which shows the luminance distribution of a light-guide plate when a light source is uniformly arrange | positioned in the light-guide plate which has an uneven | corrugated shaped body, (b) is optical path conversion in the light-guide plate which has an uneven | corrugated shaped body. It is a top view which shows the luminance distribution of the light-guide plate at the time of changing the pattern density of a part. It is a graph which shows an example of the arrangement | positioning density pattern of LED provided in the end surface of the light-guide plate in the said light source module. It is a graph which shows another example in the arrangement | positioning density pattern of LED provided in the end surface of the light-guide plate in the said light source module. It is a graph which shows another example of the arrangement | positioning density pattern of LED provided in the end surface of the light-guide plate in the said light source module. It is a graph which shows another example of the arrangement | positioning density pattern of LED provided in the end surface of the light-guide plate in the said light source module. It is a graph which shows another example of the arrangement | positioning density pattern of LED provided in the end surface of the light-guide plate in the said light source module. It is a graph which shows another example of the arrangement | positioning density pattern of LED provided in the end surface of the light-guide plate in the said light source module. (A) and (b) are top views which show the specific LED arrangement position of the LED arrangement density pattern shown in FIG. (A) is a graph which shows the arrangement | positioning density pattern when LED is provided in equal pitch to the left-right dimension +/- 25% of the end surface of the light-guide plate in the said light source module, (b) is the light-guide plate in the said light source module FIG. 6 is a graph showing an arrangement density pattern when LEDs are provided with an average arrangement density of 0.93 (pieces / unit length) up to ± 25% of the left and right dimensions of the end face of FIG. 5 is a graph showing an arrangement density pattern when LEDs are provided with an average arrangement density of 0.92 (pieces / unit length) up to ± 25% in the horizontal dimension of the end face of the light guide plate. It is a graph which shows the luminance distribution to the horizontal dimension +/- 25% of the light-guide plate in the arrangement | positioning density pattern of LED shown to Fig.17 (a) (b) (c). It is a top view which shows nine points on the light-guide plate for measuring the brightness nonuniformity of the said light-guide plate. (A) is a top view which shows the structure of the light guide plate in the conventional light source module, (b) is a bottom view which shows the structure of the said light guide plate. It is a top view which shows the structure of the light-guide plate in the other conventional light source module.

An embodiment of the present invention will be described with reference to FIGS. 1 to 19 as follows.

(Configuration of liquid crystal display device)
First, an overall configuration of a liquid crystal display device including the light source module according to the present embodiment will be described with reference to FIGS. FIG. 2 is an exploded perspective view showing a configuration of a liquid crystal display device provided with the light source module of the present embodiment. FIG. 3 is a cross-sectional view of the main part showing the configuration of the liquid crystal display device.

As shown in FIG. 2, the liquid crystal display device 1 including the light source module 10 according to the present embodiment includes a chassis 2, a light source module 10, a liquid crystal panel 3, and a bezel 4 in order from the rear. 10 includes a reflection sheet 11, a light guide plate 20, a lower diffusion sheet 17, and an upper diffusion sheet 18. Note that the configurations of the lower diffusion sheet 17 and the upper diffusion sheet 18 are examples, and for example, a so-called microlens sheet may be used.

As shown in FIG. 3, a light source provided with an LED 12, a LED substrate 13, and a reflector 14 on the side of at least one end face 20a of the pair of end faces 20a and 20a of the light guide plate 20 of the light source module 10 is provided. A unit 15 is provided. In addition, a plurality of optical path conversion units 16 for taking out light guided inside the light guide plate 20 is provided on the lower surface 20c as a surface opposite to the light exit surface 20b of the light guide plate 20. ing. The optical path conversion unit 16 is made of, for example, a scatterer formed by printing ink containing a microprism, a microlens, or a diffusing material.

Thus, the light from the LED 12 is incident on one end face 20a of the light guide plate 20, and the light is guided while being totally reflected inside the light guide plate 20, and a plurality of optical paths provided on the lower surface 20c of the light guide plate 20 The total reflection condition is broken by the conversion unit 16, and the liquid crystal panel 3 is irradiated with light from the emission surface 20 b of the light guide plate 20 through the lower diffusion sheet 17 and the upper diffusion sheet 18.

Therefore, the light source module 10 of the present embodiment employs a side edge (also referred to as side light) method. Note that light is emitted from the light guide plate 20 from surfaces other than the emission surface 20b. However, since the reflection sheet 11 is disposed on a surface other than the light exit surface 20b of the light guide plate 20 and the surface on which the LEDs 12 are disposed, and is incident on the light guide plate 20 again, most of the light is emitted from the light exit surface 20b. Emitted. Here, the light source unit 15 is provided on only one of the pair of end surfaces 20a along the longitudinal direction of the light guide plate 20, for example. However, the present invention is not necessarily limited thereto, and the light source unit 15 may be provided on both the pair of end surfaces 20 a along the longitudinal direction of the light guide plate 20. In addition, the light source unit 15 may be provided on at least one of the pair of end surfaces 20 a along the short direction of the light guide plate 20.

(Configuration of light source module)
As shown in FIG. 4, the light guide plate 20 in the light source module 10 according to the present embodiment has a shape of the emission surface 20 b along a direction perpendicular to the end surface 20 a on which light from the plurality of LEDs 12 in the light source unit 15 is incident. A plurality of streak-like uneven bodies T are formed. Specifically, the plurality of streak-like concavo-convex shapes T are formed by arranging a plurality of curved structures each having a curved surface having an arcuate cross section. This uneven | corrugated shaped body T ... is formed as a streak pattern along the transversal direction of the light-guide plate 20, for example. In other words, the light guide plate 20 includes a plurality of concave and convex shapes T each having a curved surface having a ridge line parallel to the short direction on the light emission surface 20b. The concavo-convex shaped body T is a structure formed on the emission surface 20 b of the light guide plate 20, and is not provided on the light guide plate 20 as a separate member from the light guide plate 20.

In the light guide plate 20 including the emission surface 20b having the plurality of streaky uneven shapes T, the light scattered by the optical path changing unit 16 is caused by the uneven shape T as shown in FIG. The emitted light is refracted toward the center of the concavo-convex shaped body T. For this reason, the uneven shape body T can suppress the spread of light to the side, and the straightness of the emitted light can be improved. That is, the light beam emitted from the light guide plate 20 is collected. As a result, the average luminance of the entire screen in the liquid crystal panel 3 can be improved.

By the way, in the case of a light guide plate having a conventional light exit surface, a prism sheet is provided between the lower diffusion sheet 17 and the upper diffusion sheet 18 to ensure the function of increasing the straightness of the emitted light. It was. However, in the light source module 10 according to the present embodiment, by providing the light guide plate 20 with a plurality of concavo-convex shaped bodies T, the average luminance of the entire screen in the liquid crystal panel 3 can be improved as compared with the case where a prism sheet is provided. It is possible. For this reason, in the light source module 10 of this Embodiment, the prism sheet is not provided. However, the present invention is not necessarily limited to this, and a prism sheet can be provided.

Here, in order to improve such straightness of the emitted light, as shown in FIG. 5, the height of the light guide plate 20 in the vertical direction is set to H, and the pitch between the concavo-convex shaped bodies T is set to P. The aspect ratio H / P is
0.1 <H / P <0.5
It is preferable to have a relationship satisfying This is because by setting the aspect ratio H / P in the range of 0.1 to 0.5, fluctuation due to light interference can be reduced and characteristic fluctuation of the light source module 10 can be suppressed.

The specific shape of the concavo-convex shape body T for providing such an effect is preferably a semicircular cross section as shown in FIG. In this case, the light can be efficiently extracted at various incident angles from the vertical light A rising vertically to the light C guided at a shallow angle, and the light can be emitted from the emission surface. Further, when the thickness of the light guide plate 20 is the same, the shape shown in FIG. 6A can easily ensure a larger cross-sectional area than the prism shape described later. As a result, in the configuration in which the uneven surface T having a semicircular cross section is formed on the light exit surface 20b of the light guide plate 20, the light coupling efficiency on the light incident surface from the LED 12 is high, and light leakage hardly occurs. Such a shape can be formed by extruding the light guide plate 20.

Here, the structure of the concavo-convex shaped body T is not necessarily the semicircular cross-section shown in FIG. 6A, but may be a shape shown in FIGS. 6B, 6C, and 6D.

6 (b) is a structure in which a prism with an apex angle of 90 ° is formed on the exit surface 20b of the light guide plate 20. In this case, the vertical light A becomes return light without breaking the total reflection condition. Further, the light C guided at a shallow angle is once emitted from the emission surface because the total reflection condition is broken. However, the light again enters the adjacent prism and returns to the light guide plate 20.

The concave / convex shaped body T shown in FIG. 6C is formed by forming a prism having an apex angle of 5 ° on the light exit surface of the light guide plate 20. In this case, the vertical light A and the light C guided at a shallow angle are both emitted from the emission surface because the total reflection conditions are broken. However, the probability that these lights will re-enter the adjacent prism increases.

Therefore, as shown in FIGS. 6B and 6C, when a prism is formed on the light emission surface 20b of the light guide plate 20, the efficiency of emitting light from the light guide plate 20 to confine light in the light guide plate 20 is reduced. May end up.

Further, the concavo-convex shaped body T shown in FIG. 6D has a structure having a concave cylinder surface that is recessed with respect to the emission surface 20 b of the light guide plate 20. In this case, the vertical light A does not become return light due to total reflection. Therefore, the concavo-convex shape body T shown in FIG. 6D can emit light from the light guide plate 20 more efficiently than the configuration shown in FIGS. 6B and 6C. .

(Measures against uneven luminance distribution)
In the light source module 10 using the light guide plate 20 having the emission surface 20b having the plurality of streaky uneven shapes T described above, the straightness of the emitted light is improved, so that the average of the entire screen in the liquid crystal panel 3 is improved. It has the merit that the luminance can be improved. However, on the contrary, there arises a new problem that non-uniformity of the luminance distribution occurs due to the use of the light guide plate 20 provided with the emission surface 20b having a plurality of streak-like uneven bodies T.

That is, as described above, the liquid crystal display device 1 such as a television is originally easy to see that the luminance at the center of the screen in the liquid crystal panel 3 is high and the luminance decreases toward the end side. ing.

Therefore, in a light source module that employs a side edge (also referred to as a side light) system, when the arrangement pitch of the LEDs 12 is made uniform, in a conventional light guide plate having a flat emission surface, an optical path conversion unit is arranged. The pattern is arranged so that the density is higher at the center of the lower surface of the light guide plate.

In this case, in a conventional light guide plate having a flat exit surface, as shown in FIG. 7A, light from the LED incident from the end face of the light guide plate is propagated in the light guide plate while spreading radially. The As a result, as shown in FIG. 7B, light leakage from the side surface of the light guide plate increases.

Therefore, in a conventional light guide plate having a flat emission surface, for example, by increasing the LED arrangement density, that is, by reducing the LED arrangement pitch in consideration of light leakage from the side surface of the light guide plate. The brightness at the center of the screen is increased.

However, when the LED arrangement density is increased by reducing the LED arrangement pitch, it is applied to the light guide plate 20 having the emission surface 20b having a plurality of streak-like uneven bodies T ... FIG. As shown in FIG. 8A, the light from the LED 12 of the light source unit 15 that has entered from the end face of the light guide plate 20 has high straightness, so that the light from the side surface of the light guide plate 20 is shown in FIG. Light leakage from the side surface of the light guide plate is reduced. That is, since the light rays are confined by the concavo-convex shape body T, the light rays reaching the side surface are reduced. As a result, the luminance of the emission surface 20b in the vicinity of the side surface of the light guide plate 20 increases, the luminance at the center of the screen of the liquid crystal panel 3 increases, and the ideal system of luminance distribution that the luminance decreases toward the end side is broken.

Therefore, when the optical path changing unit 16 at the center of the light guide plate 20 is increased in order to increase the brightness at the center of the screen in the liquid crystal panel 3, light leakage from the side surface is caused as shown in FIGS. Since the screen edge S becomes brighter, the luminance distribution is disturbed. That is, as shown in FIG. 9B, since the LED light has a straight traveling property, the LED light at both ends of the light guide plate 20 is hardly involved in the luminance of the central region. In addition, the ratio of light extraction between the both end regions and the central region of the light guide plate 20 is substantially proportional to the average pattern density of the optical path conversion unit 16 in each region. Furthermore, when producing a luminance distribution in which the luminance is highest at the center and lower at both side edges, light that is not extracted in both side edge regions is surely leaked light.

In this case, it is possible to block the light leakage with a light shielding tape or the like, but the efficiency with respect to the LED luminous flux decreases. Moreover, although it is possible to take the method of lowering the incident light beam at both ends of the light guide plate 20 by performing individual control of the LEDs, it causes an increase in cost. In other words, it goes against the spirit of effective and efficient use of energy.

Therefore, in the light source module 10 of the present embodiment, the distribution of the amount of light by the plurality of LEDs 12 is such that the center side is closer to the end side than the end side, as shown in FIG. The amount of light is increasing.

That is, in the present embodiment, the luminance distribution of the light guide plate 20 is adjusted by adjusting the LEDs 12 instead of the method of adjusting the pattern density of the optical path conversion unit 16. In this case, the brightness of each LED 12 is assumed to be the same. However, the present invention is not necessarily limited to this, and the brightness of each LED 12 can be different from each other.

Here, as a method of making the light amount distribution at the center larger than the end side in the light amount distribution by the plurality of LEDs 12..., There are a method of adjusting the arrangement density of the LEDs 12 and a method of adjusting the luminance of the LEDs 12.

First, a method for adjusting the distribution of the amount of light by adjusting the arrangement density of the LEDs 12 will be described with reference to FIGS. 10 to 15 and FIGS. 16 (a) and 16 (b). 10 to 15 are graphs showing an example of the arrangement density pattern of the LEDs 12 provided on the end surface 20a of the light guide plate 20 in the light source module 10. FIG. 16 (a) and 16 (b) are plan views showing specific LED 12 arrangement positions in the LED 12 arrangement density pattern shown in FIG. 10 to 15, the LED density on the vertical axis represents the LED arrangement density, and is defined by the number of LEDs 12 per unit length as the arrangement density of LEDs 12 per unit area. . Specifically, the unit of LED density on the vertical axis is pieces / cm. In addition, the horizontal axis indicates the horizontal dimension of the light guide plate 20 from 0 to ± 100% from the center to the left and right ends.

Here, in this embodiment, in any of FIGS. 10 to 15, the arrangement density of the LEDs 12 is basically larger in the center in the direction along the end surface 20a of the light guide plate 20 than in the end side. ing.

First, as shown in FIG. 10, the arrangement density of the LEDs 12 is a curve in which the arrangement pitch of each LED 12 becomes a gentle curve in the direction along the end surface 20 a of the light guide plate 20 from the center to the end side. It can be assumed that it decreases continuously. When such an arrangement density of the LEDs 12 is adopted, a luminance distribution reflecting the arrangement density distribution of the LEDs 12 in this graph can be obtained on the emission surface 20 b of the light guide plate 20.

Next, as shown in FIG. 11, the arrangement density of the LEDs 12 is such that the arrangement pitch of the LEDs 12 is gradually increased in the direction along the end surface 20 a of the light guide plate 20 from the center to the end side. It can be said that it is decreasing. Thus, when the number of LEDs 12 is small, such a step-like density distribution can be obtained.

Next, as shown in FIG. 12, the arrangement density of the LEDs 12 is such that the arrangement pitch of the LEDs 12 is gradually increased from the center to the end side in the direction along the end surface 20 a of the light guide plate 20. It can be said that it is decreasing. However, although the center is not the maximum density, the arrangement density pattern of the LEDs 12 is such that the central region has the maximum density. As described above, even in the light guide plate 20 having the concavo-convex shape body T, there is a certain amount of propagation of the propagation light. Therefore, if the center is not the maximum but has the maximum arrangement density in the vicinity of the center, the light guide plate 20 A luminance distribution having the maximum luminance at the center can be obtained.

Next, as shown in FIG. 13, the arrangement density of the LEDs 12 is such that the arrangement pitch of the LEDs 12 is continuously linear in the direction along the end surface 20 a of the light guide plate 20 from the center to the end side. It can be said that it is decreasing. In this example, the gradient of decrease in the arrangement density is stronger than the arrangement density pattern of the LEDs 12 shown in FIG. However, in the luminance distribution of the light guide plate 20, since the spread of the propagation light exists inside the light guide plate 20, the luminance distribution does not decrease linearly.

Next, as shown in FIG. 14, the arrangement density of the LEDs 12 is such that the center is the maximum density in the direction along the end surface 20 a of the light guide plate 20, and has a minimum value and a maximum value between both ends. The value can be an arrangement density pattern that does not exceed the center density.

When such an arrangement density of the LEDs 12 is adopted, the luminance in the vicinity of the end portion of the light guide plate 20 can be partially increased, so that the luminance at the end portion in the longitudinal direction should not be excessively decreased. Is possible.

For example, as will be described later, it is possible to create a distribution in accordance with a luminance standard that places importance on the luminance ratio at 1/9 points from the center and end of the light guide plate 20.

Next, as shown in FIG. 15, the arrangement density of the LEDs 12 has the maximum density in the central region in the direction along the end face 20a of the light guide plate 20, and the arrangement density of the LEDs 12 is reduced by about 10% in other cases. An arrangement density pattern can be obtained.

When such an arrangement density of the LEDs 12 is adopted, the density at the both ends decreases along the direction of the end face 20a of the light guide plate 20, and thus the opposite side to the light incident surface of the LEDs 12 at both ends. The amount of light leakage from the end face 20a is small.

As shown in FIG. 16 (a), the LED 12 is disposed at a uniform density at the same pitch in the arrangement density pattern of the LEDs 12, and the others are rough at the equal pitch. That is, the arrangement positions of the plurality of LEDs 12 provided along the end surface 20a of the light guide plate 20 are arranged such that the arrangement pitch of each LED 12 becomes closer to the end side from the center, and six LEDs 12 become dense at the center. The both ends are rougher than that, and are set so as to increase in two stages. In addition, the arrangement | positioning position of this LED12 is an illustration, Comprising: You may set so that it may become large in steps for every other one or more LED12.

In addition, as shown in FIG.16 (b), such arrangement | positioning of LED12 manufactures what divided LED board 13 which has the arrangement position of LED12 shown in FIG. You may wear it together. Thereby, an increase in the number of parts can be prevented.

Next, the relationship between the arrangement density pattern of the LEDs 12 and the luminance distribution of the light guide plate 20 will be described with reference to FIGS. 17 (a), (b), (c) and FIG. FIG. 17A is a graph showing an arrangement density pattern when the LEDs 12 are provided at equal pitches within ± 25% in the left-right dimension of the end face of the light guide plate 20 in the light source module 10, and FIG. It is a graph which shows the arrangement | positioning density pattern when it is provided by the average arrangement | positioning density of 0.93 (piece | unit / unit length), (c) is the LED12 with an average arrangement density of 0.92 (piece / unit) similarly. It is a graph which shows the arrangement | positioning density pattern when it is provided by (length). 18 is a graph showing the luminance distribution up to ± 25% in the left-right dimension of the light guide plate in the LED arrangement density pattern shown in FIGS. 17 (a), 17 (b), and 17 (c).

That is, the arrangement density pattern of the LEDs 12 in FIG. 17A is one LED 12 per unit length and is arranged at an equal pitch, so the average density in the arrangement density pattern of the LEDs 12 is It is 1. The unit length is, for example, 1 cm, and the pitch of the LEDs 12 is, for example, 10 mm. Also, in FIG. 17B, as in FIG. 11, the arrangement pitch of the LEDs 12 decreases continuously in stages from the center to the end side, and the average arrangement density of the LEDs 12 Is 0.93 (piece / unit length). Further, FIG. 17 (c) is a modified example of FIG. 10 or FIG. 10, in which the arrangement pitch of each LED 12 is continuously reduced step by step from the center to the end side. The average arrangement density of the LEDs 12 is 0.92 (pieces / unit length).

In these cases, as shown in FIG. 18, the luminance distribution on the light guide plate 20 has a decrease in luminance within −5% at the center of the light guide plate 20. On the other hand, at both ends of the light guide plate 20, in the case of the LEDs 12 having the same pitch, the brightness rapidly decreases as shown by the solid line in FIG. 18, whereas in the case of the LEDs 12 having the unequal pitch, the broken lines in FIG. Thus, the brightness | luminance fall in the both ends of the light-guide plate 20 is relieve | moderated. In this way, by arranging the LEDs 12 with unequal pitches, it is possible to create a luminance distribution in which the end of the light guide plate 20 does not become extremely dark while ensuring the luminance at the center of the light guide plate 20. For example, as shown in FIG. 9B, for example, when there is 10% leakage light in the B region, the incident light quantity of the LED 12 in the B region is reduced by 10% with respect to the A region. Also in the region, the maximum extraction pattern density of the optical path changing unit 16, that is, the pattern density with a small leakage light ratio can be formed, and the entire loss can be suppressed. Moreover, there is no need to increase the number of LEDs 12 unnecessarily, leading to a reduction in power consumption.

As described above, there is a method of adjusting the arrangement density of the LEDs 12 as a method of making the light amount distribution at the center larger than the end side of the distribution of the light amounts of the plurality of LEDs 12. Is also possible.

That is, for example, as the luminance of each LED 12, the luminance of the central LED 12 is the highest in the direction along the end surface where the light is incident, and the luminance can be decreased as the LED 12 becomes the end side. For example, the luminance of the central LED 12 is, for example, 500 cd / m 2, and the luminance of the LED 12 on the end side is, for example, 300 cd / m 2.

Thereby, it is possible to obtain a light amount distribution in which the light amount in the center is larger than that on the end side. As a result, it is possible to suppress light leakage generated at the screen edge of the liquid crystal panel 3 and to make the luminance distribution non-uniform.

Also, as a method of adjusting the brightness of the LED 12, it is possible to adjust the power input to the LED 12. Specifically, the power input to each LED 12 in the plurality of LEDs 12 provided along the end surface 20a of the light guide plate 20 is made larger at the center LED 12 than at the end LED 12.

In addition, when adjusting the brightness | luminance or electric power of LED12 like these, the arrangement | positioning pitch of LED12 may be equal pitch.

Here, the following criteria can be used as the luminance distribution of the entire light guide plate 20.

That is, as shown in FIG. 19, the position of W (horizontal width) / 9 from the center point of the light guide plate 20 and the left and right end portions of the light guide plate 20 at the vertical and horizontal center lines of the light guide plate 20 or the top and bottom 4 points at a position of V (vertical width) / 9 from each end of the light guide, W (horizontal width) / 9 from the left and right ends of the light guide plate 20, and V (vertical width) / 9 from each of the top and bottom ends Measure the luminance at 9 points with 4 points at the position.

At this time, the luminance of each of the nine points is set so that the ratio of the minimum luminance to the maximum luminance is 50% or more. In order to obtain such a luminance ratio, the arrangement pitch of the LEDs 12 may be adjusted to be 50% or more at the position of W (width) / 9, and the luminance of the LED 12 in the center is W ( You may set it high so that it may become 50% or more compared with the point of (width) / 9. Alternatively, the power may be adjusted similarly.

Thereby, it is possible to provide the light source module 10 that can surely make the luminance distribution non-uniform on the emission surface 20b of the light guide plate 20 of the light source module 10.

As described above, the light source module 10 according to the present embodiment includes the light guide plate 20 that emits the light incident in the direction perpendicular to the end surface 20a from at least one of the pair of opposed end surfaces 20a, and the light guide plate 20. And a plurality of optical path conversion units for extracting light guided inside the light guide plate 20 to the lower surface 20c of the light guide plate 20 opposite to the light exit surface 20b. 16. A plurality of streak-like uneven bodies T are formed on the exit surface 20b of the light guide plate 20 along a direction perpendicular to the end surface 20a on which light is incident.

As described above, in the case where a plurality of streaky uneven bodies T are formed on the exit surface 20b of the light guide plate 20 along the direction perpendicular to the end surface 20a on which light is incident, the LED 12 travels straight in the exit light. Therefore, the spread of light in a direction parallel to the incident surface can be suppressed.

However, when the LEDs 12 are uniformly arranged, if the pattern density of the optical path conversion unit 16 is relatively increased in order to increase the luminance of the central portion of the light guide plate 20, light extraction is sufficient in the central region of the light guide plate 20. Therefore, light leakage at the opposite end surface of the light incident surface is small, but since the pattern density is lower than the central region in both end regions, light extraction is not sufficient and leakage light is generated. As a result, the luminance distribution is disturbed.

Therefore, in the present embodiment, the distribution of the amount of light by the plurality of LEDs 12 is such that the amount of light at the center is larger than that at the end of the end surface 20a where light enters. As a result, in the direction parallel to the end face 20a on which the light is incident, a light quantity distribution is created by the plurality of LEDs 12... And a natural luminance distribution can be realized on the exit face 20b of the light guide plate 20.

Therefore, when the exit surface 20b has a cross-sectional shape, it is possible to provide the light source module 10 that can suppress the light leakage generated at the end portion and make the luminance distribution non-uniform.

Further, in the light source module 10 of the present embodiment, the arrangement density per unit area in the plurality of LEDs 12 provided along the end surface 20a of the light guide plate 20 is larger at the center than at the end side.

Thereby, as the light amount distribution adjustment, the arrangement density per unit area in the plurality of light sources is made larger at the center than at the end side. As a result, the luminance on the end side of the light guide plate 20 can be reduced, so that light leakage occurring at the end can be suppressed.

Further, in the light source module 10 of the present embodiment, the luminances emitted from the respective LEDs 12 are the same.

Thereby, the arrangement density per unit area of the plurality of LEDs 12 is made larger at the center than at the end side under the condition that the luminances emitted from the LEDs 12 are the same.

Therefore, since the brightness of the LEDs 12 is the same, the brightness on the end side of the light guide plate 20 can be reduced with a simple configuration without controlling the amount of light of the LEDs 12, and light leakage occurring at the ends can be prevented. Can be suppressed.

Moreover, in the light source module 10 of this Embodiment, the arrangement | positioning position of several LED12 provided along the end surface 20a of the light-guide plate 20 is at least the arrangement | positioning pitch of each LED12 as it becomes an edge part side from the center. One or more light sources are set to increase in steps.

Thereby, it is possible to provide a specific arrangement position of the plurality of LEDs 12 for reducing the luminance on the end portion side of the light guide plate 20.

In the light source module 10 of the present embodiment, the brightness of each LED 12 is preferably such that the center LED 12 is the largest on the end face 20a on which the light is incident and the LED 12 on the end side becomes smaller.

Thereby, the light quantity distribution is adjusted by changing the luminance of the LED 12. As a result, for example, even when the arrangement pitches of the LEDs 12 are equal, by adjusting the luminance of the LEDs 12, the light amount is larger at the center than at the end side on the end surface 20a on which light is incident. The distribution of the amount of light can be obtained.

In the light source module 10 of the present embodiment, the power input to each LED 12 in the plurality of LEDs 12 provided along the end surface 20a of the light guide plate 20 is larger in the central light source than in the end light source.

Thereby, the light quantity distribution is adjusted by adjusting the power input to the LED 12. As a result, for example, even when the arrangement pitches of the LEDs 12 are equal, by adjusting the electric power input to the LEDs 12, the amount of light at the center is larger than that at the ends on the end surface 20a where light enters. The distribution of the amount of light can be obtained.

In the light source module 10 of the present embodiment, the position of W (horizontal width) / 9 from the center point of the light guide plate 20 and the left and right ends of the light guide plate 20 at the vertical and horizontal center lines of the light guide plate 20 or Four points at the position of V (vertical width) / 9 from the upper and lower ends, W (horizontal width) / 9 from the left and right ends of the light guide plate, and V (vertical width) / 9 from the upper and lower ends Any of the arrangement density of LEDs 12, the brightness of each LED 12, or the power of each LED 12 is set so that the ratio of the minimum brightness to the maximum brightness when measuring each of the 9 brightnesses at 4 points is 50% or more. It is preferable that at least one is set.

Thereby, it is possible to provide the light source module 10 that can surely make the luminance distribution non-uniform on the emission surface of the light guide plate 20 of the light source module 10.

In addition, the liquid crystal display device 1 of the present embodiment includes an overlying light source module 10.

According to said structure, when it has the uneven | corrugated shaped body T in the output surface 20b of the light-guide plate 20, the light source module 10 which can suppress the light leakage which generate | occur | produces at an edge part and can aim at nonuniformity of luminance distribution is provided. The liquid crystal display device 1 can be provided.

The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and can be obtained by appropriately combining technical means disclosed in different embodiments. Embodiments are also included in the technical scope of the present invention.

The present invention relates to a light source module and a liquid crystal display device including a side edge (also referred to as a sidelight) type light guide plate that emits light from a light source in a planar shape by a light guide plate. For example, a light source module such as a backlight. In addition, the liquid crystal display device can be applied to a liquid crystal display device such as a monitor of a television, a tablet, or a personal computer.

DESCRIPTION OF SYMBOLS 1 Liquid crystal display device 3 Liquid crystal panel 10 Light source module 12 LED (light source)
DESCRIPTION OF SYMBOLS 15 Light source unit 16 Optical path conversion part 17 Lower diffusion sheet 18 Upper diffusion sheet 20 Light guide plate

20a End surface

20b Output surface 20c Lower surface (surface)
T Uneven shape body

Claims

A light guide plate that emits from the exit surface light incident in a direction perpendicular to the end surface from at least one of a pair of opposing end surfaces, a plurality of light sources that enter the light to the light guide plate, and a light exit surface of the light guide plate In a light source module comprising a plurality of optical path conversion units for extracting light guided inside the light guide plate on the opposite side surface,
On the exit surface of the light guide plate, a plurality of streaky irregularities along the direction perpendicular to the end surface on which the light is incident are formed, and
The light quantity distribution by the plurality of light sources is characterized in that the light quantity at the center is larger than the edge side at the end face where the light is incident.
2. The light source module according to claim 1, wherein the arrangement density per unit area in the plurality of light sources provided along the end face of the light guide plate is larger in the center than in the end side.
The light source module according to claim 2, wherein the luminances emitted from the light sources are the same.
As for the arrangement positions of the plurality of light sources provided along the end face of the light guide plate, the arrangement pitch of each light source is increased stepwise for at least one or more light sources as it moves from the center to the end side. The light source module according to claim 3, wherein the light source module is set as follows.
The light source module according to claim 1, wherein the brightness of each light source is such that the central light source is the largest at the end face where the light is incident, and decreases as the light source is on the end side.
6. The light source module according to claim 5, wherein the power input to each light source in the plurality of light sources provided along the end face of the light guide plate is larger in the central light source than in the end light source.
From the center point of the light guide plate and the left and right ends of the light guide plate at the vertical and horizontal center lines of the light guide plate, W (horizontal width) / 9 positions or V (vertical width) / 9 points of brightness, 4 points at 9 positions, and 4 points at W (horizontal width) / 9 from the left and right ends of the light guide plate and V (vertical width) / 9 from the top and bottom ends At least one of the arrangement density of the light sources, the luminance of each light source, and the power of each light source is set so that the ratio of the minimum luminance to the maximum luminance when measuring is 50% or more. The light source module according to any one of claims 1 to 6.
A liquid crystal display device comprising the light source module according to any one of claims 1 to 7.