WO2014185120A1

WO2014185120A1 - Illuminator and display device

Info

Publication number: WO2014185120A1
Application number: PCT/JP2014/054827
Authority: WO
Inventors: 角田　行広
Original assignee: シャープ株式会社
Priority date: 2013-05-14
Filing date: 2014-02-27
Publication date: 2014-11-20

Abstract

A backlight device (30) is provided with: a light-guide plate (20) formed from a plate of glass, the light-guide plate (20) having, towards one end face, a step section (22) comprising a step bottom surface (22a) provided following the plate surface of the light-guide plate (20) and a step side surface (22b) provided following the end face of the light-guide plate (20), the step side surface (22b) serving as a light entry side; and, on the step bottom surface (22a), side-emitting LED light sources (26) arranged in a form wherein the entirety of the light-emitting surface of each faces the step side surface (22b). Since the LED light sources (26) are arranged on a portion of the light-guide plate (20), the LED light sources (26) can be positioned precisely relative to the light-guide plate (20). In addition, since the LED light sources (26) are arranged in a form wherein the entirety of the light-emitting surface of each faces the light entry surface, satisfactory entry efficiency can be maintained.

Description

Lighting device and display device

The present invention relates to a lighting device and a display device.

2. Description of the Related Art Display devices including a display panel such as a liquid crystal panel are used for portable information terminal devices such as mobile phones, smartphones, and tablet laptop computers, and electronic devices such as computers. Since the liquid crystal panel used for the display device does not emit light, the display device requires a backlight device as a separate illumination device. Backlight devices are roughly classified into direct type and edge light type according to the mechanism, and it is preferable to use an edge light type backlight device in order to realize further thinning of the liquid crystal display device. ing.

In an edge light type backlight device, a light guide plate that guides light emitted from a light source such as an LED (Light Emitting Diode) to a light emitting surface provided on one of the plate surfaces is accommodated in the housing. The The light guide plate is provided with a light incident surface on at least one end surface side thereof, and a light source is arranged to face the light incident surface. In this type of backlight device, it is required to improve the incident efficiency of the light emitted from the light source with respect to the light incident surface of the light guide plate in order to increase the luminance and the uniformity of the luminance on the display surface. For example, Patent Document 1 discloses a liquid crystal display device including a backlight in which the incidence efficiency is improved.

JP 2010-72262 A

(Problems to be solved by the invention)
However, in the liquid crystal display device described in Patent Document 1, the LED light source block on which the LED light source is mounted is fixed to a panel frame that forms a part of the housing and is arranged apart from the light guide plate. Has been. For this reason, when manufacturing a backlight or when receiving an impact from the outside, the LED light source may be displaced with respect to the light incident surface in the thickness direction of the light guide plate. When the LED light source is displaced with respect to the light incident surface, the incident efficiency of the light from the light source on the light incident surface may be reduced. In particular, in a backlight device in which the light guide plate is thinned, the amount of reduction in incident efficiency due to a positional shift with respect to the light incident surface of the LED light source is significant.

The technology disclosed in this specification has been created in view of the above problems. In this specification, it aims at providing the technique which can improve the positioning accuracy of the LED light source with respect to a light-guide plate, maintaining favorable incident efficiency.

(Means for solving the problem)
The technology disclosed in the present specification is a plate-shaped glass light guide plate, on at least one end surface side, a step bottom surface provided along the plate surface of the light guide plate, and the light guide plate A light guide plate having a stepped side surface provided along the end surface, the stepped side surface being a light incident surface, and the entire light emitting surface of the stepped bottom surface facing the stepped side surface. And a side-emitting LED light source arranged in a shape.

According to the illuminating device described above, the LED light source is arranged directly on the step portion provided on the light guide plate. Therefore, even when the light guide plate is thinned, the LED light source is not attached to the light guide plate. Positioning can be performed with high accuracy. Further, since the LED light source is arranged in such a manner that the entire light emitting surface faces the light incident surface, it is possible to maintain good incident efficiency with respect to the light incident surface of the light guide plate. Furthermore, since the light guide plate is made of glass, the coefficient of expansion due to heat or the like is smaller than when the light guide plate is made of resin or the like, and even when heat or the like is generated from the LED light source, the LED light source is It is difficult to shift. As described above, in the illumination device described above, the positioning accuracy of the LED light source with respect to the light guide plate can be improved while maintaining good incident efficiency.

A wiring pattern for supplying power to the LED light source may be formed on the step bottom surface.
According to this configuration, the space for arranging the wiring for the LED light source can be saved, and thus the light guide plate can be thinned.

The LED light source may include an LED element and a sealing resin that seals the LED element.
According to this configuration, the wiring pattern can be simplified as compared with the case where the LED element is exposed and disposed on the bottom surface of the step.

The LED light source may be configured such that the entire surface directed to the step side surface faces the step side surface.
According to this structure, the incident efficiency with respect to the light-incidence surface of a light-guide plate can be improved compared with the case where a part of sealing resin of a LED light source is not facing the level | step difference side surface.

A first diffusion pattern that imparts an optical action to the light emitted from the LED light source may be formed on the light incident surface.
According to this configuration, the distribution of light incident on the light incident surface can be relaxed by the first diffusion pattern, and the incident efficiency with respect to the light incident surface of the light guide plate can be increased.

A second diffusion pattern that imparts an optical action to the light emitted from the LED light source may be formed on one plate surface of the light guide plate.
According to this configuration, the point-shaped light can be converted into planar light by the second diffusion pattern, and uneven brightness of the light emitted from the light guide plate can be prevented or suppressed.

A plate surface on which the second diffusion pattern of the light guide plate is formed may be a rough surface, and the second diffusion pattern may be increased as the distance from the LED light source is increased.
According to this configuration, an effective pattern shape for making the light amount distribution of the light emitted from the light guide plate uniform can be formed on the plate surface of the light guide plate for the second wiring pattern.

The LED light source may be arranged such that the height of the center position of the light emitting surface is equal to the height of the center position of the step side surface in the thickness direction of the light guide plate.
According to this configuration, since the light emitted from the LED light source is efficiently incident on the light incident surface, the incident efficiency with respect to the light incident surface of the light guide plate can be further increased.

The light guide plate may have a wedge shape whose thickness decreases from an end surface side where the step portion is provided to an end surface side opposite thereto.
According to this structure, illumination efficiency can be improved compared with the case where the light-guide plate is made flat.

The step portion may be formed by a processing process for cutting a part of the light guide plate that is plate-shaped.
According to this structure, the specific manufacturing method for forming a level | step difference in a light-guide plate can be provided.

The technology disclosed in this specification can also be expressed as a display device including the above-described illumination device and a display panel that performs display using light from the illumination device. A display device in which the display panel is a liquid crystal panel in which liquid crystal is sealed between a pair of substrates is also novel and useful.

(The invention's effect)
According to the technique disclosed in this specification, the positioning accuracy of the LED light source with respect to the light guide plate can be improved while maintaining good incident efficiency.

1 is an exploded perspective view of a liquid crystal display device according to Embodiment 1. FIG. Cross section of liquid crystal display An enlarged cross-sectional view of a light guide plate on which an LED light source is mounted Plan view of light guide plate and LED light source Side view of the light guide plate in the process of manufacturing the light guide plate on which the LED light source is mounted and preparing the light guide plate Side view of the light guide plate in the manufacturing process of the light guide plate on which the LED light source is mounted and forming the stepped portion Side view of the light guide plate after the step portion is formed in the manufacturing process of the light guide plate on which the LED light source is mounted The side view of the said light-guide plate of the manufacturing process of the light-guide plate in which an LED light source is mounted, and the process of forming a 2nd diffused pattern in the light-projection surface of a light-guide plate is shown. Plan view of the second mask The top view of the said light-guide plate after it is a manufacturing process of the light-guide plate in which an LED light source is mounted, and forms the 2nd diffusion pattern Side view of the light guide plate in the manufacturing process of the light guide plate on which the LED light source is mounted, wherein the metal film is formed on the step bottom surface of the light guide plate. Side view of the light guide plate after a metal film is formed on the step bottom surface of the light guide plate in the manufacturing process of the light guide plate on which the LED light source is mounted Side view of the light guide plate in the manufacturing process of the light guide plate on which the LED light source is mounted, wherein the wiring pattern is formed on the step bottom surface of the light guide plate The top view which was the manufacturing process of the light-guide plate in which a LED light source is mounted, and expanded the step bottom vicinity after forming a wiring pattern in the step bottom of a light-guide plate A plan view of a manufacturing process of a light guide plate on which an LED light source is mounted, in which the vicinity of a step bottom surface after the LED light source is mounted on a wiring pattern is enlarged. The expanded sectional view which expanded the light-guide plate in which the LED light source was mounted in Embodiment 2. The expanded sectional view which expanded the light-guide plate in which the LED light source was mounted in Embodiment 3. An enlarged plan view of the vicinity of the bottom of the step where the LED light source is mounted The expanded sectional view which expanded the light-guide plate in which the LED light source was mounted in Embodiment 4. Table showing the relationship between the thickness of the light guide plate and the incident efficiency with respect to the positional deviation of the LED light source

<Embodiment 1>
Embodiment 1 will be described with reference to the drawings. In this embodiment, the liquid crystal display device 10 including the cover panel 12 is illustrated. In addition, a part of each drawing shows an X axis, a Y axis, and a Z axis, and each axis direction is drawn to be a direction shown in each drawing. Further, with respect to the vertical direction, FIGS. 1 and 2 are used as a reference, and the upper side of the figure is the front side and the lower side of the figure is the back side.

As shown in FIG. 1, the liquid crystal display device 10 has a vertically long rectangular shape as a whole, and a liquid crystal panel (an example of a display panel) 14 whose front side plate surface is a display surface for displaying an image, and a liquid crystal A cover panel 12 arranged to face the display surface of the panel 14 and an external light source arranged on the opposite side of the cover panel 12 with the liquid crystal panel 14 interposed therebetween and supplying light to the liquid crystal panel 14 And a backlight device (an example of a lighting device) 30. The liquid crystal display device 10 further includes a casing 36 that houses the cover panel 12, the liquid crystal panel 14, and the backlight device 30. Of the components of the liquid crystal display device 10, the cover panel 12 and the casing 36 constitute the appearance of the liquid crystal display device 10. The liquid crystal display device 10 according to the present embodiment includes a portable information terminal (such as a mobile phone, a smartphone, and a tablet notebook computer), an in-vehicle information terminal (such as a stationary car navigation system and a portable car navigation system), and a portable game. It is used for various electronic devices such as a machine. For this reason, the screen sizes of the liquid crystal panel 14 and the cover panel 12 constituting the liquid crystal display device 10 are about several inches to several tens of inches, and are generally classified into small or medium-sized.

First, the liquid crystal panel 14 will be described. As shown in FIG. 1, the liquid crystal panel 14 has a vertically long rectangular shape as a whole, and is formed between a pair of transparent (translucent)

glass substrates

14a and 14b and both the

substrates

14a and 14b. And a liquid crystal layer (not shown) including liquid crystal molecules which are interposed and whose optical characteristics change with application of an electric field. Both the

substrates

14a and 14b are bonded together by a sealing agent (not shown) while maintaining a gap corresponding to the thickness of the liquid crystal layer. Of the two

substrates

14a and 14b, the back side (back side) is the array substrate 14b, and the front side (front side) is the CF substrate 14a. The array substrate 11b is provided with a switching element (for example, TFT) connected to the source wiring and the gate wiring orthogonal to each other, a pixel electrode connected to the switching element, an alignment film, and the like. Are provided with a color filter in which colored portions such as R (red), G (green), and B (blue) are arranged in a predetermined arrangement, a counter electrode, and an alignment film. Among these, as shown in FIG. 1, the CF substrate 14a has a short side dimension substantially the same as the array substrate 14b, but has a long side dimension smaller than that of the array substrate 11b. Then, they are bonded together with one end in the long side direction aligned. Accordingly, the other end of the array substrate 14b in the long side direction is in a state where both the front and back plate surfaces are exposed to the outside, and a driver 15 for driving the liquid crystal panel 14 and a panel side flexible A mounting area for a substrate (not shown) is secured. As a result, image data and various control signals necessary for displaying an image from a drive circuit board (not shown) are supplied to the source wiring, the gate wiring, the counter electrode, and the like. A polarizing plate (not shown) is disposed outside both substrates.

The cover panel 12 is arranged so as to cover the entire area of the liquid crystal panel 14 from the front side, whereby the liquid crystal panel 14 can be protected. A liquid crystal panel 14 is attached to the center side portion of the cover panel 12 via an adhesive (not shown) on the plate surface on the back side. The cover panel 12 has a vertically long rectangular shape, similar to the liquid crystal panel 14, and the size of the cover panel 12 as viewed in a plane is slightly larger than the

substrates

14 a and 14 b forming the liquid crystal panel 14. Almost the same level. Therefore, the outer peripheral side portion of the cover panel 12 protrudes outward in a bowl shape from the outer peripheral end of the liquid crystal panel 14. The cover panel 12 is formed with a light shielding portion 12a that shields light around it. The light shielding portion 12a is provided by printing means such as screen printing or ink jet printing. The light shielding portion 12a is also formed on the outer peripheral side portion that protrudes outward from the outer peripheral end of the liquid crystal panel 14, thereby forming a vertically long substantially frame shape (substantially frame shape), and thereby the backlight device 30. Can be shielded by the light shielding portion 12a before entering the plate surface on the back side of the cover panel 12 around the liquid crystal panel.

The casing 36 is made of a synthetic resin material or a metal material, and has a substantially bowl shape opened toward the front side, as shown in FIG. The cover panel 12, the liquid crystal panel 14, and the backlight device 30 are accommodated in an accommodation space held inside the casing 36. Therefore, the casing 36 covers the backlight device 30 from the back side, and covers the backlight device 30 and the cover panel 12 from the side over the entire circumference, thereby configuring the appearance of the back side and the side surface side of the liquid crystal display device 10. ing. In addition, the casing 36 has a substantially stepped outer peripheral portion, and has the lowest first step portion 36a and the second lowest second step portion 36b. Of the casing 36, between the second step portion 34 b facing the frame 32 constituting the backlight device 30 and the back surface of the frame 32, a casing adhesive tape 35 that adheres to both is interposed. It is arranged in a form.

The casing adhesive tape 35 has a flexible tape-like base material, and an adhesive is applied to both the front and back surfaces of the base material. The casing 36 and the frame 22 are kept in an attached state by the casing adhesive tape 35. Moreover, since the casing adhesive tape 35 is formed in a substantially vertically long frame shape as a whole in accordance with the shape of the frame 32 to be adhered, the casing 36 and the frame 32 are fixed substantially over the entire circumference. A part of the casing adhesive tape 35 is also affixed to an outer peripheral end of a reflection sheet 34 to be described later. Further, in the space left between the first step portion 36 a of the casing 36 and the back side of the backlight device 30, driving power is supplied to a control board for controlling the driving of the liquid crystal panel 14 and an LED light source 26 described later. A substrate (not shown) such as an LED drive substrate to be supplied is accommodated.

Next, the backlight device 30 will be described. The backlight device 30 includes an LED light source 26 mounted thereon, a light guide plate 20 that guides light from the LED light source 26, an optical member 18 that is stacked on the light guide plate 20, and a stack below the light guide plate 20. The reflection sheet 34 to be disposed, and a frame-like frame 32 that surrounds the light guide plate 20 and the optical member 18 and supports the liquid crystal panel 14 from the back side (the side opposite to the cover panel 12 side). The backlight device 30 is a so-called edge light type (side light type) in which the LED light source 26 is unevenly distributed at the outer peripheral end of the liquid crystal panel 14. Hereinafter, each component of the backlight device 30 will be described.

As shown in FIG. 2, the optical member 18 has a horizontally long rectangular shape as viewed in a plane, like the liquid crystal panel 14. The optical member 18 is slightly smaller than the plate surface of the light guide plate 20 described later, and the entire optical member 18 is placed on the front side (light emission side) of the light guide plate 20 and between the liquid crystal panel 14 and the light guide plate 20. Accordingly, the light emitted from the light guide plate 20 is transmitted and emitted toward the liquid crystal panel 14 while applying a predetermined optical action to the transmitted light. The optical member 18 is composed of a plurality of sheet-like members stacked on each other. Specifically, the optical member 18 includes, in order from the light guide plate 20 side, a diffusion sheet 18a that diffuses light emitted from the light guide plate 20, a first lens sheet 18b that collects light transmitted through the diffusion sheet 18a, and The second lens sheet 18c is used.

The reflection sheet 34 has a rectangular sheet shape, is made of synthetic resin, and has a white surface with excellent light reflectivity. Most of the reflection sheet 34 is in surface contact with the opposite plate surface 20c of the light guide plate 20 to be described later, and its edge is also in contact with the back side of the frame 22 to be described later. As described above, the casing adhesive tape 35 is used. The outer periphery of the casing 36 is supported by the second step portion 36 b of the casing 36. In the reflection sheet 34, both end portions in the long side direction (Y-axis direction) extend outward from both end surfaces forming the short side of the light guide plate 20.

The frame 32 is made of a synthetic resin, and as shown in FIG. 1, the frame 32 has a vertically long substantially frame shape whose outer shape is substantially the same as that of the cover panel 12, and the liquid crystal panel 14, the light guide plate 20, and the optical member are disposed inside the frame 32. 18 is accommodated. The frame 32 includes a pair of short side portions that extend along the X-axis direction and a pair of long side portions that extend along the Y-axis direction. The frame 32 is opposed to the outer peripheral end portion of the cover panel 12 where the light shielding portion 12a is formed and the plate surface on the back side of the liquid crystal panel 14 and can support the plate surface from the back side over the entire circumference. . As shown in FIGS. 1 and 2, the frame 32 has a substantially stepped shape with a three-dimensional cross section, and the second lowest step supports the outer peripheral end of the liquid crystal panel 14 from the back side, and is the highest. The step portion supports the outer peripheral end of the cover panel 12 from the back side. A substantially frame-shaped panel adhesive tape 16 that adheres to the frame 32 and the liquid crystal panel 14 is disposed between the frame 32 and the liquid crystal panel 14, and the liquid crystal panel 14 and the frame 32 are disposed by the panel adhesive tape 16. It is designed to be kept in a state where the space between is attached. On the other hand, a slightly recessed step is provided on the back side of the frame 32, so that a slight gap is formed between the casing 36 and the frame 32. As shown in FIG. 2, the outer peripheral end of the reflection sheet 35 is accommodated in this gap.

The light guide plate 20 is a plate-shaped member having a rectangular shape and a thickness greater than that of the optical member 18, and is made of glass having a refractive index higher than that of air and being transparent (excellent in translucency). The glass material forming the light guide plate 20 is, for example, aluminosilicate glass. In the light guide plate 20, the short side direction on the plate surface coincides with the X-axis direction, the long side direction coincides with the Y-axis direction, and the plate thickness direction orthogonal to the plate surface coincides with the Z-axis direction. As shown in FIGS. 1 and 2, the light guide plate 20 is disposed immediately below the liquid crystal panel 14 and the optical member 18 in a state surrounded by a frame 32 described later. Of the plate surfaces of the light guide plate 20, the surface facing the front side (the surface facing the liquid crystal panel 14 and the optical member 18) transmits the internal light to the optical member 18 and the liquid crystal panel 14 as shown in FIGS. 1 and 2. It becomes the light-projection surface 20b radiate | emitted toward the side. On the other hand, the plate surface (back surface) opposite to the light emitting surface 20b is an opposite plate surface 20c. A step portion 22 described below is provided on one end face 20a side (the left side shown in FIGS. 1 and 2) of both end faces provided along the X-axis direction in the light guide plate 20. The other end face among the both end faces provided along the X-axis direction in the light guide plate 20 is an opposite end face 20d.

As shown in FIG. 2, the stepped portion 22 provided on one end surface 20 a side of the light guide plate 20 is provided in a shape that forms a step with respect to the light emitting surface 20 b, and is formed on the plate surface of the light guide plate 20. A step bottom surface 22 a provided along the step and a step side surface 22 b provided along the end surface of the light guide plate 20 are provided. A wiring pattern 28 is provided on most of the step bottom surface 22 a in the step portion 22. A plurality of LED light sources 26 to be described later are mounted on the wiring pattern 28 such that the light emitting surface 24a faces the step side surface 22b. The step side surface 22 b is opposed to the light emitting surface 24 a of the LED light source 26, thereby forming a light incident surface 22 b on which light emitted from each LED light source 28 is incident. Therefore, hereinafter, the step side surface 22b is also referred to as a light incident surface 22b, and the light incident surface 22b is also referred to as a step side surface 22b. The light guide plate 20 introduces the light emitted from each LED 28 from the light incident surface 20a and rises toward the optical member 18 side (front side, light emission side) while propagating the light inside, thereby emitting the light. It has the function to emit from 20b. As shown in FIG. 3, a diffusion sheet (an example of a first diffusion pattern) 51 is bonded to the light incident surface 22b of the light guide plate 20, thereby distributing the light incident on the light incident surface 22b. The incident efficiency with respect to the light incident surface 22b of the light guide plate 20 can be increased. Further, a diffusion pattern (an example of a second diffusion pattern) 21 (see FIG. 10, not shown in FIG. 4) is formed on the light emitting surface 20 b of the light guide plate 20. The diffusion pattern 21 is composed of a plurality of

circular patterns

21a, 21b, and 21c whose diameter, that is, the area is increased stepwise as the distance from the step portion 22 (LED light source 26) increases. Thus, the light amount distribution in the surface of the light emitted from the light emitting surface 20a is controlled to be uniform.

As shown in FIGS. 3 and 4, the plurality of LED light sources 26 are mounted in parallel on the wiring pattern 28 formed on the step bottom surface 22 a along the short side direction (X-axis direction) of the light guide plate 20. The LED element 24 is sealed with a sealing resin 25. Each LED light source 26 is mounted on the wiring pattern 28 so that driving power is supplied via the wiring pattern 28. The LED element 24 has a single main emission wavelength, and specifically, one that emits blue in a single color is used. On the other hand, the resin material that seals the LED element 24 is dispersed and blended with phosphors that are excited by the blue light emitted from the LED element 24 and emit a predetermined color, and generally emit white light. It is supposed to be emitted. In addition, as the phosphor, for example, a yellow phosphor that emits yellow light, a green phosphor that emits green light, and a red phosphor that emits red light are used in appropriate combination, or any one of them is used. It can be used alone. These LED light sources 26 are of a so-called side light emitting type in which one side surface is a light emitting surface 24a when the surface mounted on the wiring pattern 28 is the front surface (or the back surface). Each LED light source 26 has a light emitting surface 24a on the step bottom surface 22a that forms the step portion 22 as described above, and the light emitting plate 24 is close to the light incident surface 20a that forms the step portion 22 of the light guide plate 20. A plurality are arranged in a row (linearly) in parallel along a short side direction (X-axis direction) of 20 with a predetermined interval.

As shown in FIG. 3, each LED light source 26 has a shape in which the entire surface (including the light emitting surface 24a) including the sealing resin 25 among the surfaces directed toward the light incident surface 22b faces the light incident surface 22b. It is arranged with. Specifically, the thickness (Z-axis direction dimension) T1 of the light incident surface 22b of the light guide plate 20 is substantially equal to the height (Z-axis direction dimension) of the LED light source 26. Further, each LED light source 26 is configured such that, in the thickness direction (Z-axis direction) of the light guide plate 20, the height of the central position of the light emitting surface 24a is equal to the height of the central position of the step side surface (light incident surface) 22b. It is arranged. Therefore, in this embodiment, the positional deviation distance of the LED light source 26 with respect to the light incident surface 22b of the light guide plate 20 is ± 0 in the thickness direction (Z-axis direction) of the light guide plate 20. For this reason, most of the light emitted from each LED light source 26 is incident on the light incident surface 22b, and the incident efficiency is extremely high.

Subsequently, a method for manufacturing the light guide plate 20 on which the LED light source 26 according to this embodiment is mounted will be described with reference to FIGS. First, as shown in FIG. 5, a glass substrate 50 having a rectangular plate shape is used as a light emitting surface 20 b (hereinafter referred to as a front side plate surface) 50 b with the light emitting surface 20 b A plate surface (hereinafter referred to as a back side plate surface) 50c to be prepared is prepared with the back side facing. Next, as shown in FIG. 6, the first mask 40 is placed on a portion of the front side plate surface 50 b of the substrate 50 excluding the end surface 50 a side on which the light incident surface 22 b is formed. The first mask 40 is a mask in which a pattern such as an opening is not formed. Next, a portion of the front side plate surface 50b where the first mask 40 is not placed is excavated to a predetermined depth along the thickness direction (Z-axis direction) of the light guide plate 20 by sandblasting. As a result, as shown in FIG. 7, a stepped portion 22 forming a step is formed in a portion of the front side plate surface 50b that is not covered with the first mask 40. By forming the stepped portion 22, the portion of the front side plate surface 50b covered with the first mask 40 is the light emitting surface 20b, and the stepped side surface 22b that forms the stepped portion 22 is the light incident surface 22b. The

Next, as shown in FIG. 8, the second mask 41 is placed on the light emitting surface 20b. As shown in FIG. 9, the second mask 41 is formed with an opening pattern 41 composed of a plurality of

circular opening groups

41a, 41b, 41c. The plurality of

aperture groups

41 a, 41 b, 41 c have shapes and arrangements corresponding to the second diffusion pattern 21 formed on the light emitting surface 20 b of the light guide plate 20. Specifically, the opening diameters of the

opening groups

41a, 41b, and 41c increase in three stages from one end side of the second mask 41 toward the opposite side. And when mounting the 2nd mask 41 on the light-projection surface 20b, the state which orient | assigned the side with a small opening diameter to the side in which the level | step-difference part 22 was formed among several opening

groups

41a, 41b, and 41c. Place in. Next, the diffusion pattern 21 corresponding to the opening pattern 41 of the second mask 41 is formed on the light emitting surface 20b by sandblasting. As a result, as shown in FIG. 10, a diffusion pattern 21 composed of a plurality of

circular patterns

21 a, 21 b, 21 c whose diameter gradually increases as the distance from the stepped portion 22 increases is formed on the light emitting surface 20 b. It is formed.

Next, as shown in FIG. 11, a third mask 42 is placed on the light emitting surface 20b. The third mask 42 is a mask in which a pattern such as an opening is not formed as in the first mask 40. Next, as shown in FIG. 12, a metal film 29 is formed on the step bottom surface 22a of the step portion 22 by the sputtering method, that is, the portion on which the front side third mask 42 is not placed. Next, as shown in FIG. 13, a fourth mask having a pattern corresponding to the wiring pattern 28 formed on the step bottom surface 22a is placed on the metal film 29 on the step bottom surface 22a. Next, the wiring pattern 28 is formed from the metal film 29 formed on the step bottom surface 22a by photolithography.

Here, FIG. 14 shows a plan view of the wiring pattern 28 formed on the step bottom surface 22a as viewed from the front side. As shown in FIG. 14, the wiring pattern 28 includes an anode terminal 28a and a cathode terminal 28b formed on one end side in the short side direction (X-axis direction) of the light guide plate 20 on the step bottom surface 22a, and an LED light source. 26 comprises a pair of electrode groups 28c formed at locations corresponding to the locations where 26 is mounted, and connection wirings 28d connecting them. After the wiring pattern 28 is formed, the diffusion sheet 31 is disposed on the surface of the step side surface 22b and fixed by adhesion or the like.

Next, as shown in FIG. 15, solder paste is applied to portions corresponding to the pair of electrode groups 28 c on the wiring pattern 28, and the LED light source 26 is mounted. Through the above steps, the light guide plate 20 on which the LED light source 26 is mounted can be manufactured. In addition, one end side of the wiring is electrically connected to the anode terminal 28a and the cathode terminal 28b formed on the wiring pattern 28, and the above-described LED driving board and the like are electrically connected to the other end side of the wiring. . As a result, power is supplied from the LED drive board to each LED light source 26 via the wiring pattern 28, and the drive of each LED light source 26 is controlled.

Now, since each LED light source 26 is directly mounted on the step portion 22 formed in a part of the light guide plate 20 manufactured as described above, the backlight device 30 is impacted from the manufacturing process or from the outside. When received, each LED light source 26 is not easily displaced with respect to the light incident surface 22b formed in the stepped portion 22. Specifically, if the LED light source 26 is mounted on a flexible flexible substrate and the flexible substrate is incorporated in the backlight device 30, the flexible substrate is deformed by bending or the like. Therefore, there is a concern that the LED light source is displaced in the thickness direction of the light guide plate 20 with respect to the light guide plate 20. On the other hand, the light guide plate 20 according to the present embodiment is made of glass that is higher in rigidity (rigid) than a flexible substrate and the like, and a step portion 22 on which the LED light source 26 is mounted is formed in a part thereof. Thus, the LED light source 26 mounted on the stepped portion 22 is extremely unlikely to be displaced in the thickness direction of the light guide plate 20 with respect to the light incident surface 22b.

Here, FIG. 20 shows the position of the LED light source with respect to the light incident surface when the thickness of the light incident surface formed on the light guide plate (the dimension along the thickness direction of the light guide plate) is t (mm). The table | surface which represented the difference in the incident efficiency by the difference in the position shift distance (mm) along the thickness direction of an optical plate in percentage. As shown in the table of FIG. 20, the incident efficiency is more easily affected by the positional deviation of the LED light source as the light guide plate is thinner. In this regard, in the backlight device 30 of the present embodiment, each LED light source 26 is arranged such that the entire surface directed toward the light incident surface 22b is opposed to the light incident surface 22b. The positional shift distance along the thickness direction (Z-axis direction) of the light guide plate 20 with respect to the light incident surface 22b is ± 0 mm, and an incident efficiency close to 100% can be obtained. Therefore, in the backlight device 30 of the present embodiment, a configuration in which the LED light source 26 is not easily displaced with respect to the light incident surface 22b while maintaining an incident efficiency close to 100% is realized.

As described above, in the backlight device 30 according to the present embodiment, the LED light source 26 is directly disposed on the step portion 22 provided in the light guide plate 20, so that the light guide plate 20 is thinned. Even if it exists, the LED light source 26 can be accurately positioned with respect to the light guide plate 20. In addition, since the LED light source 26 is disposed so that the entire light emitting surface 24 a faces the light incident surface 20, it is possible to maintain good incident efficiency with respect to the light incident surface 22 b of the light guide plate 20. Furthermore, since the light guide plate 20 is made of glass, the coefficient of expansion due to heat or the like is small compared to the case where the light guide plate 20 is made of resin or the like, and the LED light source 26 emits light even when heat or the like is generated from the LED light source 26. It is difficult to be displaced with respect to the incident surface 22b. As described above, in the backlight device 30 of the present embodiment, the positioning accuracy of the LED light source 26 with respect to the light guide plate 20 can be improved while maintaining good incident efficiency.

In the present embodiment, the wiring pattern 28 for supplying power to the LED light source 26 is formed on the step bottom surface 22 a of the step portion 22. With such a configuration, it is possible to save the space for arranging the wiring for the LED light source 26, thereby reducing the thickness of the light guide plate 20.

In the present embodiment, each LED light source 26 includes an LED element 24 and a sealing resin 25 that seals the LED element 24. Furthermore, each LED light source 26 is configured such that the entire surface directed toward the step side surface 22b faces the step side surface 22b. With such a configuration, the wiring pattern 28 can be simplified as compared with the case where the LED element 24 is exposed and disposed on the step bottom surface 22a. Moreover, the incident efficiency with respect to the light-incidence surface 22b of the light-guide plate 20 can be improved compared with the case where some sealing resin 25 of the LED light source 26 is not facing the level | step difference side surface 22b.

In the present embodiment, a diffusion sheet that gives an optical action to the light emitted from the LED light source 26 is bonded to the light incident surface 20. Furthermore, a diffusion pattern that imparts an optical action to the light emitted from the LED light source 26 is formed on the light emitting surface 20 b of the light guide plate 20. With such a configuration, the distribution of light incident on the light incident surface 22b can be relaxed by the diffusion sheet, and the incident efficiency with respect to the light incident surface 22b of the light guide plate 20 can be increased. Further, the diffused pattern can convert the spot light into the planar light, and the luminance unevenness of the light emitted from the light guide plate 20 can be prevented or suppressed.

In the present embodiment, each LED light source 26 has a height at the center position of the light emitting surface 24a in the thickness direction (Z-axis direction) of the light guide plate 20 and a height at the center position of the step side surface (light incident surface) 22b. It is arranged to be equal. With such a configuration, the light emitted from each LED light source 26 is efficiently incident on the light incident surface 22b, so that the incident efficiency with respect to the light incident surface 22b of the light guide plate 20 is further increased. be able to.

In addition, the incident efficiency with respect to the light incident surface 22b also affects the distance between the light incident surface 22b and the LED light source 26. Here, in the conventional configuration in which the LED light source is arranged on the flexible substrate, the mounting accuracy of the flexible substrate on the chassis or the like affects the distance between the light incident surface and the LED light source. In this regard, in the present embodiment, the LED light source 26 is directly disposed on the light guide plate 20, so that the mounting accuracy of such a flexible substrate does not become a problem with respect to the incident efficiency. For this reason, incident efficiency can be improved compared with the conventional structure by which the LED light source was distribute | arranged on the flexible substrate.

<Modification of Embodiment 1>
Subsequently, a modification of the first embodiment will be described. In this modification, a part of the manufacturing process of the light guide plate 20 on which the LED light source 26 is mounted is different from that of the first embodiment, and the configuration of the backlight device 30 is the same as that of the first embodiment. In this modification, in the manufacturing process of the light guide plate 20 on which the LED light source 26 is mounted, a mask is formed on the step bottom surface 22a by photolithography before the diffusion pattern 21 is formed on the light emitting surface 20b, and sandblasting is performed. The light emitting surface 22b is roughened by a method or the like. Thereafter, the diffusion pattern 21 is formed on the roughened light emitting surface 22b. By forming the diffusion pattern 21 in this way, an effective pattern shape for making the light quantity distribution of the light emitted from the light guide plate 20 uniform for the diffusion pattern 21 is the light emission surface 20b of the light guide plate 20. Can be formed on top.

<Embodiment 2>
A second embodiment will be described with reference to the drawings. In the second embodiment, the shape of the light guide plate 120 is different from that of the first embodiment. Since the other configuration is the same as that of the first embodiment, the description of the structure, operation, and effect is omitted. In FIG. 16, the part obtained by adding the numeral 100 to the reference numeral in FIG. 3 is the same as the part described in the first embodiment.

In the backlight device according to Embodiment 2, the light guide plate 120 has a wedge shape, as shown in FIG. Specifically, the light guide plate 120 has a shape in which the thickness decreases from the end surface 120a side where the stepped portion 122 is provided toward the opposite end surface 120d side by making the opposite plate surface 120c an inclined surface. It has become. Since the light guide plate 20 has such a shape, the uniformity of the light amount distribution of the light emitted from the light guide plate 20 can be improved, and illumination is performed as compared with the case where the light guide plate 20 has a flat plate shape. Efficiency can be increased.

<Embodiment 3>
Embodiment 3 will be described with reference to the drawings. The third embodiment is different from the first embodiment in the configuration of the LED light source 226 and the mounting mode on the step bottom surface 222a. Since the other configuration is the same as that of the first embodiment, the description of the structure, operation, and effect is omitted. In FIGS. 17 and 18, the portions obtained by adding the numeral 200 to the reference numerals in FIGS. 3 and 14 are the same as the portions described in the first embodiment.

In the backlight device according to the third embodiment, as shown in FIGS. 17 and 18, each LED light source 226 is composed of only the LED element 224 exposed. Specifically, each LED light source 226 includes three LED

elements

224R, 224G, and 224B arranged adjacent to each other. That is, each LED light source 226 is configured to obtain white light as one light source using three LED

elements

224R, 224G, and 224B including a red LED element 224R, a green LED element 224G, and a blue LED element 224B. . Here, the three

LED elements

224R, 224G, and 224B that constitute each LED light source 226 have different required voltages. Therefore, as shown in FIG. 18, with respect to the wiring pattern 228 formed on the step bottom surface 222a, Three systems of connection wirings 228d corresponding to the red LED element 224R, the green LED element 224G, and the blue LED element 224B are required. For this reason, the

LED elements

224R, 224G, and 224B are mounted on the step bottom surface 222a so that the distances from the light incident surface 222b are shifted from each other.

Further, each

LED element

224R, 224G, 224B constituting each LED light source 226 is provided with

lens members

246R, 246G, 246B so as to cover the light emitting surface. As described above, since the

LED elements

224R, 224G, and 224B are displaced from each other from the light incident surface 222b, as shown in FIG. 18, the thickness of the

lens members

246R, 246G, and 246B is set to the respective LED elements. By adjusting for each of 224R, 224G, and 224B, the distance from the light incident surface 222b is made constant for each of the

lens members

246R, 246G, and 246B. For this reason, in this embodiment, even if each LED light source 226 is configured to include three

LED elements

224R, 224G, and 224B, the incident efficiencies of light emitted from the

LED elements

224R, 224G, and 224B are made equal. As a result, the LED light source 226 as a whole can obtain good incident efficiency.

<Embodiment 4>
Embodiment 4 will be described with reference to the drawings. In the fourth embodiment, the thickness of the portion of the light guide plate 320 where the step 322 is formed is different from that of the first embodiment. Since the other configuration is the same as that of the first embodiment, the description of the structure, operation, and effect is omitted. In FIG. 19, the part obtained by adding the numeral 300 to the reference numeral in FIG. 3 is the same as the part described in the first embodiment.

In the backlight device according to the fourth embodiment, when the step portion 322 is formed in the manufacturing process of the light guide plate 320 on which the LED light source 326 is mounted, the portion where the step portion 322 is formed has a deeper depth than that of the first embodiment. It has been excavated. Thereby, as shown in FIG. 19, the thickness of the site | part in which the level | step-difference part 322 of the light-guide plate 320 was formed is a thing thinner than the thing of Embodiment 1. FIG. With such a configuration, the upper surface 326a of the LED light source 326 is located at a position closer to the lower side than the upper end of the light incident surface 322b, in other words, lower than the light emitting surface 320b. For this reason, the incident efficiency with respect to the light incident surface 322b of the LED light source 326 can be further enhanced while realizing a configuration in which the LED light source 326 is not easily displaced with respect to the light incident surface 322b.

The modifications of the above embodiments are listed below.
(1) In the above embodiments, the configuration in which the stepped portion is formed on one end side of the light guide plate is illustrated, but the configuration in which the stepped portion is formed on a plurality of end portions of the light guide plate may be employed.

(2) In each of the above embodiments, an example in which the step portion is formed on the light guide plate by the sand blast method has been shown. However, the step portion may be formed on the light guide plate by other methods such as etching or glass polishing.

(3) In each of the above-described embodiments, the configuration in which the diffusion sheet is bonded to the light incident surface is exemplified. However, a configuration in which a prism sheet or the like is bonded to the light incident surface may be used. Moreover, it is not limited to adhesion | attachment, You may fix a diffusion sheet to a light-incidence surface by another method.

(4) In each of the above embodiments, an example in which the diffusion sheet is bonded to the side surface of the step after forming the wiring pattern on the bottom surface of the step is shown. However, after the step portion is formed, the diffusion sheet is bonded to the side surface of the step. There is no limitation on the order to be performed.

(5) In each of the above embodiments, an example in which the diffusion pattern is formed on the light emission surface by the sandblast method has been described. However, the diffusion pattern may be formed on the light emission surface by other methods such as printing.

(6) In each of the above embodiments, the configuration in which the diffusion pattern is formed on the light emission surface is illustrated, but the configuration in which the diffusion pattern is formed on the opposite plate surface may be used, or on the light emission surface. And a configuration in which a diffusion pattern is formed on both of the opposite plate surfaces. When a diffusion pattern is formed on both the light output surface and the opposite plate surface, the density of the diffusion pattern is halved in the light guide plate manufacturing process, and each of the patterns is distributed between the light output surface and the opposite plate surface. Good.

(7) In the above embodiment, each LED light source has exemplified the configuration in which the entire surface directed toward the light incident surface side is mounted on the bottom surface of the step so as to face the light incident surface. The light source may be mounted on the bottom surface of the step so that at least the entire light emitting surface faces the light incident surface.

(8) In each of the above-described embodiments, the optical sheet is configured to include two prism sheets and one diffusion sheet. However, the number and types of optical sheets used can be changed as appropriate. For example, a reflective polarizing sheet or the like can be added.

(9) In each of the above embodiments, the backlight device constituting the liquid crystal display device including the liquid crystal panel having a size classified as small or medium-sized is exemplified. However, the liquid crystal panel having a size classified as a large size is used. The present invention is also applicable to a backlight device constituting a liquid crystal display device provided.

(10) In each of the above embodiments, a liquid crystal display device using a liquid crystal panel as the display panel has been illustrated, but the present invention can also be applied to a display device using another type of display panel.

As mentioned above, although each embodiment of this invention was described in detail, these are only illustrations and do not limit a claim. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.

Next, the present invention will be specifically described with reference to examples. First, as a substrate used for manufacturing the light guide plate, a 4.3-inch size substrate, specifically, a vertical direction (long side direction) dimension of 96.5 mm, a horizontal direction (short side direction) dimension of 54.4 mm, A 0.7 mm thick glass substrate (AN100 manufactured by Asahi Glass Co., Ltd.) was used.

In the step of forming the stepped portion, the thickness of the portion where the stepped portion is formed is 0.3 mm, that is, the depth of excavation is 0.4 mm, and the width (the light incident surface from the end surface on the stepped portion side of the light guide plate). The step portion was formed so that the dimension of the step was 3.0 mm. Thereby, a light incident surface having a thickness of 0.4 mm was formed.

Regarding the diffusion pattern to be formed on the light emitting surface, the pattern formation region has a vertical dimension of 90.5 mm and a horizontal dimension of 54 mm. In the diffusion pattern, the diameter of the circular pattern on the side where the step portion is formed is about 0.0022 mm, and the diameter of the circular pattern on the side opposite to the side where the step portion is formed is about 0.02 mm. Formed as follows.

A white LED (NSSE206) manufactured by Nichia Corporation was used as the LED light source to be mounted on the step bottom surface of the step portion. In addition, Thin-BEF films manufactured by 3M were used for the two lens sheets constituting the optical member, and HBS-706 manufactured by Eiwa Co., Ltd. was used for the diffusion sheet.

Moreover, the mounting accuracy of the LED light source on the wiring pattern was set within a range of ± 0.05 mm in the direction in which the step side surface and the LED light source are arranged (Y-axis direction). Thereby, the distance between the step side surface (light incident surface) and the LED light source is made highly uniform for each LED light source.

As described above, the LED light source is directly mounted on the stepped portion formed on the light guide plate as compared with the backlight device having a configuration in which the LED light source is mounted on the flexible substrate separated from the light guide plate. Even when the light source plate is less likely to be displaced and the light guide plate is made thinner, a backlight device capable of obtaining a highly uniform luminance can be manufactured without lowering the incident efficiency.

DESCRIPTION OF SYMBOLS 10 ... Liquid crystal display device, 14 ... Liquid crystal panel, 18 ... Optical member, 20, 120, 220, 320 ... Light guide plate, 22, 122, 222, 322 ... Step part, 22a, 122a, 222a, 322a ... Step bottom surface, 22b , 122b, 222b, 322b ... step side surface (light incident surface), 26, 126, 226, 326 ... LED light source, 28, 128, 228, 328 ... wiring pattern, 30 ... backlight device, 32 ... frame, 36 ... casing

Claims

A glass-made light guide plate having a plate shape, a step bottom surface provided along the plate surface of the light guide plate on at least one end surface side, and a step side surface provided along the end surface of the light guide plate A light guide plate provided with a stepped portion, wherein the step side surface is a light incident surface,
A side-emitting LED light source disposed on the bottom surface of the step so that the entire light emitting surface faces the step side surface;
A lighting device comprising:
The lighting device according to claim 1, wherein a wiring pattern for supplying power to the LED light source is formed on the bottom surface of the step.
The lighting device according to claim 2, wherein the LED light source includes an LED element and a sealing resin that seals the LED element.
The lighting device according to claim 3, wherein the entire surface of the LED light source facing the step side is opposed to the step side.
The lighting device according to any one of claims 1 to 4, wherein a first diffusion pattern that imparts an optical action to light emitted from the LED light source is formed on the light incident surface.
The illumination according to any one of claims 1 to 5, wherein a second diffusion pattern that imparts an optical action to the light emitted from the LED light source is formed on one plate surface of the light guide plate. apparatus.
The plate surface on which the second diffusion pattern of the light guide plate is formed is a rough surface,
The lighting device according to claim 6, wherein the second diffusion pattern is increased as the distance from the LED light source is increased.
The said LED light source is distribute | arranged so that the height of the center position of the said light emission surface may become equal to the height of the center position of the said level | step difference side surface in the thickness direction of the said light-guide plate. The lighting device according to claim 1.
9. The light guide plate according to claim 1, wherein the light guide plate has a wedge shape that decreases in thickness from an end surface side on which the stepped portion is provided to an opposite end surface side. Lighting device.
The lighting device according to any one of claims 1 to 9, wherein the stepped portion is formed by a processing process for cutting a part of the plate-shaped light guide plate.
A display device comprising: the illumination device according to any one of claims 1 to 10; and a display panel that performs display using light from the illumination device.
The display device according to claim 11, wherein the display panel is a liquid crystal panel in which liquid crystal is sealed between a pair of substrates.