WO2022149359A1

WO2022149359A1 - Display device

Info

Publication number: WO2022149359A1
Application number: PCT/JP2021/042655
Authority: WO
Inventors: 隆大田
Original assignee: 株式会社ジャパンディスプレイ
Priority date: 2021-01-08
Filing date: 2021-11-19
Publication date: 2022-07-14
Also published as: JP2024033019A

Abstract

The purpose of the present invention is to achieve a display device which has high accuracy and high contrast by using accurate local dimming. A configuration for achieving this is as follows. That is, provided is a display device having a display panel and a backlight, the display device characterized in that: the backlight has a light source and an optical sheet group; the light source has a light source board 61 and an LED 60 disposed on the light source board; the light source 60 is divided into segments when viewed in a plane view and at least one of the LED 60 is present in the segments; the light source board 61 is covered with a protective film excluding the LED; the segments are partitioned into a wall shape by a partitioning plate 70 formed of a resin; the partitioning plate 70 is placed on the protective film 63; and a convex lens 45 is formed between the partitioning plate 70 and the optical sheet group.

Description

Display device

The present invention relates to a display device having a backlight, and more particularly to a display device that enables a high-contrast screen by using local dimming.

In a liquid crystal display device, a TFT substrate in which pixel electrodes and thin film transistors (TFTs) are formed in a matrix, and a facing substrate are arranged facing the TFT substrate, and a liquid crystal layer is sandwiched between the TFT substrate and the facing substrate. There is. Then, the image is formed by controlling the transmittance of light by the liquid crystal molecules for each pixel.

On the other hand, in the organic EL display device, pixels having a light emitting element, a driving TFT, a switching TFT, and the like formed by the organic EL layer are formed in a matrix, and an image is formed by controlling the light emitting intensity of the organic EL layer for each pixel. .. Since the organic EL display device is a self-luminous element, the contrast of the image is excellent.

However, since the size of the pixels can be made smaller in the liquid crystal display device, the definition is superior in the liquid crystal display device. Therefore, local dimming has been developed as a method for improving the contrast of the liquid crystal display device. For example, Patent Document 1 exists as a prior art relating to local dimming.

JP-A-2017-116683

VR (Virtual Reality) display devices and medical display devices require higher-definition and higher-contrast images. When local dimming is used in such a display device, finer control is required for local dimming as well.

In order to perform local dimming more effectively and improve the contrast in such a display device, for example, the area of the segment that is the unit of local dimming is reduced, and the light of each segment is placed in the adjacent segment. It needs to be out of reach.

Also, if the area of the segment is reduced, it becomes difficult to arrange multiple LEDs in the segment. On the other hand, when only one LED is arranged in each segment, uniform brightness distribution becomes a problem, and there arises a problem that the LED can be seen from the screen side. If, for example, a diffusion sheet is arranged to deal with this, there arises a problem that the light of each segment leaks to the adjacent segment due to the influence of the diffusion sheet.

An object of the present invention is to solve such a problem, effectively perform local dimming, and realize a high-definition and high-contrast screen in a display device having a backlight.

The present invention solves the above problems, and the main specific means are as follows.

(1) A display device having a display panel and a backlight, wherein the backlight has a light source and an optical sheet group, the light source has a light source substrate and LEDs arranged on the light source substrate, and the light source is , The segment is divided into segments when viewed in a plane, in which at least one LED is present, the light source substrate is covered with a protective film except for the LED, and the segment is formed of resin. The display is characterized in that it is partitioned into a wall shape by a partition plate, the partition plate is placed on the protective film, and a convex lens is formed between the partition plate and the optical sheet group. Device.

(2) A display device having a display panel and a backlight, wherein the backlight has a light source and an optical sheet group, the light source has a light source substrate and an LED arranged on the light source substrate, and the light source has a light source. The segment is divided into segments when viewed in a plane, in which at least one LED is present, the light source substrate is covered with a protective film except for the LED, and the segment is covered with a protective film of the protective film. A second lens is formed on the top and so as to surround the LED, and the diameter of the second lens is larger on the optical sheet group side than on the LED side, and is between the second lens and the optical sheet group. Is a display device characterized in that a first lens is formed therein.

(3) A display device having a display panel and a backlight, wherein the backlight has a light source and an optical sheet group, the light source has a light source substrate and LEDs arranged on the light source substrate, and the light source is , The segment is divided into segments when viewed in a plane, the segment has at least one LED, the light source substrate is covered with a protective film except for the LED, and the segment is partitioned by a partition resin. A through hole is formed in the partition resin, and the cross-sectional shape of the through hole is an outwardly convex curved surface. When viewed in a plane, the diameter of the through hole is larger than that of the light source substrate on the optical sheet group side. The display device is also large, and is characterized in that a convex lens is formed between the partition resin and the optical sheet group.

It is a top view of the liquid crystal display device. It is sectional drawing of the liquid crystal display device. It is a top view which shows the example of the segment in the case of the local dimming operation in the liquid crystal display device. It is a top view of the comparative example 1 when a blue LED is used as a light source. It is sectional drawing of the comparative example 1 in the case of using a blue LED as a light source. It is a top view of the comparative example 2 when a white LED is used as a light source. It is sectional drawing of the comparative example 2 when a white LED is used as a light source. It is a top view which shows the segment of Example 1. FIG. It is sectional drawing which shows the segment of Example 1. FIG. It is a perspective view of a partition plate. It is a top view of a partition plate. 11 is a cross-sectional view taken along the line AA of FIG. It is a perspective view of the 1st lens. It is sectional drawing which shows the manufacturing method of the 1st lens. It is a graph which shows the transmittance of the exposure mask in the manufacturing method of the 1st lens. It is sectional drawing which follows FIG. 15 which shows the manufacturing method of the 1st lens. It is sectional drawing which follows FIG. 16 which shows the manufacturing method of the 1st lens. It is sectional drawing which shows the state which the partition plate is attached to the 1st lens, and this is placed on the light source substrate. It is sectional drawing of the blue LED in Comparative Examples 1 and 2 and the periphery thereof. It is sectional drawing of the blue LED in this invention and its periphery. It is sectional drawing of Example 2. FIG. It is a top view of Example 2. FIG. It is another plan view of Example 2. FIG. It is sectional drawing which shows the manufacturing method of the 2nd lens. It is a graph which shows the transmittance of the exposure mask in the manufacturing method of the 2nd lens. It is sectional drawing which follows FIG. 24 which shows the manufacturing method of the 2nd lens. It is sectional drawing which follows FIG. 25 which shows the manufacturing method of the 2nd lens. It is sectional drawing which shows the state which the 2nd lens is attached to the 1st lens, and this is placed on the light source substrate. It is sectional drawing of Example 3. FIG. It is sectional drawing which shows the manufacturing method of the convex lens of Example 3. FIG. It is sectional drawing which follows FIG. 29 which shows the manufacturing method of the convex lens of Example 3. FIG. It is sectional drawing which follows FIG. 30, which shows the manufacturing method of the convex lens of Example 3. FIG. It is sectional drawing following FIG. 31 which shows the manufacturing method of the convex lens of Example 3. FIG. It is sectional drawing which follows FIG. 32 which shows the manufacturing method of the convex lens of Example 3. FIG. It is sectional drawing of Example 4. FIG. It is a top view of Example 4. FIG. It is another plan view of Example 4. FIG. It is sectional drawing which shows the manufacturing method of Example 4. FIG. It is sectional drawing which follows FIG. 36 which shows the manufacturing method of Example 4. FIG. It is sectional drawing which follows FIG. 37 which shows the manufacturing method of Example 4. FIG. It is sectional drawing which follows FIG. 38 which shows the manufacturing method of Example 4. FIG. It is sectional drawing which shows the state which puts the assembly of the partition resin including a 1st lens and a reflection layer on a light source substrate. It is sectional drawing of Example 5. FIG. It is a top view of Example 5. FIG. It is a plan view of Example 6. It is sectional drawing of Example 6. It is sectional drawing of the white LED used in Comparative Examples 1 and 2 and the periphery thereof. It is sectional drawing of the white LED used in this invention and its periphery.

The present invention will be described in detail below with reference to examples.

FIG. 1 is a plan view showing an example of a liquid crystal display device. In FIG. 1, the TFT substrate 100 and the facing substrate 200 are adhered to each other by the sealing material 16, and the liquid crystal is sandwiched inside. A display region 14 is formed in a portion where the TFT substrate 100 and the facing substrate 200 overlap. In the display area 14, the scanning lines 11 extend in the horizontal direction (x direction) and are arranged in the vertical direction (y direction). Further, the video signal lines 12 extend in the vertical direction and are arranged in the horizontal direction. Pixels 13 are formed in a region surrounded by scanning lines 11 and video signal lines 12.

In FIG. 1, the portion where the TFT substrate 100 does not overlap with the facing substrate 200 is the terminal region 15. A flexible wiring board 17 is connected to the terminal area 15 in order to supply power and signals to the liquid crystal display panel. The driver IC that drives the liquid crystal display panel is mounted on the flexible wiring board 17. A backlight is arranged on the back surface of the TFT as shown in FIG.

FIG. 2 is a cross-sectional view of the liquid crystal display device. In FIG. 2, the backlight 20 is arranged on the back surface of the liquid crystal display panel 10. The liquid crystal display panel 10 has the following configuration. That is, the facing substrate 200 on which the black matrix and the color filter are formed is arranged so as to face the TFT substrate 100 on which the pixel electrodes, common electrodes, TFTs, scanning lines, video signal lines and the like are formed. The TFT substrate 100 and the facing substrate 200 are adhered to each other by a sealing material 16 at the periphery, and a liquid crystal 300 is enclosed inside.

The liquid crystal molecules are initially oriented by the alignment film formed on the TFT substrate 100 and the facing substrate 200. When a voltage is applied between the pixel electrode and the common electrode, the liquid crystal molecules rotate and form an image by controlling the light from the backlight 20 for each pixel. Since the liquid crystal 300 can control only the deflected light, the lower polarizing plate 101 is arranged under the TFT substrate 100, and only the deflected light is incident on the liquid crystal 300. The light modulated by the liquid crystal 300 is detected by the upper polarizing plate 201, and the image is visually recognized.

In FIG. 2, the backlight 20 is arranged on the back surface of the liquid crystal display panel. The backlight 20 has a configuration in which the light guide plate 40 is arranged on the light source 30, and the optical sheet group 50 is arranged on the light guide plate 40. The backlight 20 of the display device includes a side light system in which a light source such as an LED is arranged on the side surface of the light guide plate and a direct type in which a light source such as an LED is arranged on the lower surface of the light guide plate. Use a direct-type backlight.

In FIG. 2, the light guide plate 40 is arranged on the light source 30. The light guide plate 40 is made of a transparent resin. The light guide plate 40 in FIG. 2 has a role of making the light from the LED, which is a point light source, uniform by reflecting the light incident on the light guide plate 40 at the interface.

The optical sheet group 50 is arranged on the light guide plate 40. A prism sheet, a diffusion sheet, or the like is used for the optical sheet group 50. In addition, in order to obtain white light by using a blue LED or the like as a light source, a color conversion sheet in which a phosphor is dispersed in a resin sheet may be used. As the color conversion sheet, a QD sheet using quantum dots may be used. Further, in order to improve the utilization efficiency of the light from the backlight 20, a deflection reflection sheet may be used. What kind of optical sheet is used or how many such optical sheets are used is determined by the display device.

When displaying an image on a liquid crystal display device, the bright part transmits the light from the backlight, and the dark part shields the light from the backlight. Image contrast is defined by the ratio of bright to dark areas. In the liquid crystal display device, the dark portion is formed by shielding the light from the backlight by the liquid crystal. However, the shielding of the backlight by the liquid crystal is not perfect, and some light leaks. This will reduce the contrast.

Local dimming enables deep black display by not irradiating the dark part with the light from the backlight. Therefore, high contrast can be realized. FIG. 3 is an example of a liquid crystal display device showing a form of local dimming. FIG. 3 is a plan view of the liquid crystal display device, and the configuration is the same as that described with reference to FIG. In FIG. 3, the display area 14 is divided by segments 141. The dotted line in FIG. 3 is the boundary of the segment 141, but this is described for convenience, and the liquid crystal display panel does not have such a boundary. The light source in the backlight is arranged at the position corresponding to each segment.

In FIG. 3, it is assumed that the segment (4, 2) is a bright part and the segment (5, 2) is a dark part. In local dimming, the light source of the segment (4, 2) portion, that is, the LED is turned on, and the light source of the segment (5, 2) portion, that is, the LED is not turned on. Then, the black formed in the segment (5, 2) becomes a deep black display, and high contrast is realized.

However, since there is no boundary between the segments, for example, depending on the luminance distribution of the segment, the light of the segment (4, 2) may reach the segment (5, 2). Then, the backlight is also illuminated on the segments (5, 2) that should be displayed in black, and the effect of local dimming cannot be fully exerted.

4 and 5 are Comparative Example 1 showing the configuration of the backlight that enables local dimming. In FIGS. 4 and 5, a blue LED 60 is used as a light source. FIG. 4 is a plan view showing the arrangement of the LED 60, which is a light source, in each segment 141 of the backlight. In FIG. 4, each segment 141 is partitioned by a dotted line. However, this dotted line is for convenience only and does not actually have a partition. The size of each segment is 4 mm □ (length 4 mm, width 4 mm) or less, and in the case of FIG. 5, it is, for example, 2 mm □. The size of the segment 141 in the following example is also the same.

In FIG. 4, one LED 60 is arranged in each segment 141. FIG. 5 is a cross-sectional view of the backlight in Comparative Example 1. In FIG. 5, the LED 60 is arranged on the light source substrate 61, and the transparent resin 62 is formed so as to cover the LED 60. A blue LED is used for the LED 60. An example of the configuration of the LED 60 and its vicinity is shown in FIG. For the transparent resin 62, for example, an acrylic resin or a silicone resin is used. The transparent resin 62 is for protecting the electrodes and wiring formed on the LED 60 and the light source substrate 61. The dotted line shown on the light source substrate 61 in FIG. 5 indicates the boundary of the segment for convenience.

The light guide plate 40 is arranged on the transparent resin 62. Although the light guide plate 40 is transparent, it has a function of reflecting the light incident on the light guide plate 40 at the interface and making the light from the LED 60 uniform. The color conversion sheet 51 is arranged on the light guide plate 40. The color conversion sheet 51 is a transparent resin sheet in which a phosphor that receives blue light and develops yellow light is dispersed, and the light that has passed through the color conversion sheet 51 is white light. The thickness of the color conversion sheet 51 is, for example, 50 microns to 500 microns.

A diffusion sheet 53 is arranged on the color conversion sheet 51. The diffusion sheet 53 is for diffusing the light from the light source 60 to make the brightness uniform. The thickness of the diffusion sheet 53 is, for example, 50 microns to 70 microns. A prism sheet 52 is arranged on the diffusion sheet 53. The prism sheet 52 is formed by extending prisms having a triangular cross section in the y direction and arranging them in the x direction. The role of the prism sheet 52 is to increase the light utilization efficiency by directing the light emitted obliquely from the main surface of the color conversion sheet 51 in the direction perpendicular to the main surface of the color conversion sheet 51. In FIG. 5, the number of prism sheets 52 is one, but a prism sheet having a prism array extending in a direction perpendicular to the prism array of the prism sheet 52 in FIG. 5 may be added. The thickness of the prism sheet is, for example, 50 microns in the portion of the prism array (that is, the height of the prism) and 70 microns in the thickness of the base material portion, for a total of about 120 microns.

6 and 7 are comparative examples 2 when a white LED 65 is used as a light source. FIG. 6 is the same as FIG. 4 except that the LED as a light source is a white LED 65. FIG. 7 is a cross-sectional view of the backlight in Comparative Example 2. In FIG. 7, the white LED 65 is arranged on the light source substrate 61, and the transparent resin 62 is formed so as to cover the white LED 65. An example of the configuration of the white LED 65 and its vicinity is shown in FIG. 45.

The light guide plate 40 is arranged on the transparent resin 62. The role of the light guide plate 40 is the same as that described in Comparative Example 1. The diffusion sheet 53 exists on the light guide plate 40, and the color conversion sheet 51 does not exist. This is because the white LED 65 is used, so there is no need for color conversion. The role of the diffusion sheet 53 is the same as described in FIG. The prism sheet 52 is arranged on the diffusion sheet 53. The structure and operation of the prism sheet are the same as those described in FIG.

The problem of Comparative Examples 1 and 2 is that the light from the

LED

60 or 65 leaks from the transparent resin 63 covering the

LEDs

60 and 65, the light guide plate 40, the color conversion sheet 51 and the diffusion sheet 53 to the adjacent segments. be. In particular, light leakage to the adjacent segment via the transparent resin 62 and the light guide plate 40, which are close to the light source, is large. Therefore, accurate local dimming cannot be performed.

The present invention shown below solves the above problems. The present invention can be applied regardless of whether the LED is blue or white. The case where the blue LED 60 is used will be described in Examples 1 to 5 below, and the case where the white LED 65 is used in Example 6 will be described.

8 and 9 are the configurations of the backlight according to the first embodiment of the present invention. FIG. 8 is a plan view showing the arrangement of the LED 60, which is a light source, in each segment 141 of the backlight. The LED 60 is a blue LED. In FIG. 8, each segment 141 is partitioned by a partition plate 70. As shown in FIG. 10, the partition plate 70 is a thin plate made of resin assembled in a grid shape. The size of each segment 141 is 4 mm □ or less, for example, 2 mm □.

In FIG. 8, one LED 60 is arranged in each segment 141. Therefore, although the brightness of the LED 60 is high, in the configuration of the first embodiment, as will be described later, the amount of light leaking from the LED 60 to the adjacent segment is small, so that the brightness of the LED is higher than that of the LED in the case of the comparative example 1. It can be made smaller.

FIG. 9 is a cross-sectional view of the backlight in the first embodiment. In FIG. 9, the LED 60 is arranged on the light source substrate 61. The configuration of the LED60 portion will be described with reference to FIG. In FIG. 9, the protective film 63 is formed so as to cover the wiring and the electrodes formed on the light source substrate 61. This configuration is significantly different from Comparative Examples 1 and 2. That is, in the configuration of the first embodiment, the LED 60 is not covered with the transparent resin 62, and the light emitting region from the LED 60 exists above the protective film 63. Therefore, the protective film 63 does not have to be transparent. That is, in Example 1, the transparent resin 62 in Comparative Examples 1 and 2 does not exist.

In the configuration of FIG. 9, the protective sheet 63 should be formed of, for example, a white resin and have a high reflectance. Such a resin can be formed of, for example, a silicone resin. That is, a part of the light emitted from the LED 60 is reflected by the partition plate 70 and is incident on the protective film 63 side, but if the reflectance of the protective film 63 is large, this light is reflected again and the liquid crystal display panel. You can turn it in the direction.

In FIG. 9, a partition plate 70 exists at the boundary of the segment, and the partition plate 70 is arranged on the protective sheet 63. The partition plate 70 is made of white PET (Polyethylene terephthalate). In this embodiment, PET is used for the partition plate 70, but a white PC (polycarbonate) may be used. Further, the partition plate 70 may be integrally formed, or a plurality of divided partition plates 70 may be arranged side by side. The light emitted obliquely from the LED 60 is reflected by the partition plate 70 and heads toward the first lens 45.

In Comparative Examples 1 and 2, the light from the LED 60 leaks to the adjacent segment through the transparent resin 62 covering the LED, but in the first embodiment, as shown in FIG. 9, the light emitted from the LED 60 is a partition plate. It is configured so that it is reflected by 70 and does not leak to adjacent segments.

In FIG. 9, the first lens 45 is arranged on the partition plate 70 instead of the light guide plate. The first lens 45 has a configuration in which one convex lens is formed for each segment. The light incident on the first lens 45 does not go to the adjacent segment, but converges in the direction of the liquid crystal display panel. Therefore, light leakage to adjacent segments can be reduced.

In FIG. 9, a color conversion sheet 51 is arranged on the first lens 45. The configuration and operation of the color conversion sheet 51 are the same as those described in Comparative Example 1. A diffusion sheet 53 is arranged on the color conversion sheet 51. The role of the diffusion sheet 53 is the same as described in Comparative Example 1. In FIG. 9, the prism sheet 52 is arranged on the diffusion sheet 53, which is the same as in Comparative Examples 1 and 2. Further, the configuration and operation of the prism sheet 52 are the same as those described in Comparative Examples 1 and 2. The optical sheet group in FIG. 9 is an example, and other optical sheets may be used.

FIG. 10 is a perspective view of the partition plate 70. The partition plate 70 is a combination of white PET plates having a thickness of about 0.2 mm in a grid shape. The segment 141 is formed in the region surrounded by the partition plate 70. The size of the segment 141 is, for example, 2 mm □ (2 mm × 2 mm), and the height of the partition plate 70 is, for example, 1 mm (in the Z-axis direction).

FIG. 11 is a plan view of the partition plate 70. The plate thickness sw of the partition plate 70 is about 0.2 mm. The sizes sx and sy of the segment 141 are 4 mm or less, for example, about 2 mm. FIG. 12 is a sectional view taken along the line AA of FIG. The height sh of the partition plate 70 is 0.5 mm to 2 mm, for example, 1 mm.

FIG. 13 is a perspective view of the first lens array 45. One first lens 45 is formed for each segment. The thickness of the lens is, for example, 1 mm to 2 mm at the central portion t11. The lens is, for example, a spherical surface, and the thickness t12 around the lens is determined by the curved surface of the lens. As the lens material, for example, acrylic resin which is a transparent resin, silicone resin polycarbonate, or the like is used.

14 to 17 are sectional views showing a process of manufacturing the first lens 45. There are various methods for manufacturing a microlens array, but in this embodiment, an example of manufacturing using photolithography will be shown. As the material of the first lens 45, a transparent photosensitive resin as described above is used. In Example 1, an example using a positive photosensitive resin will be described.

FIG. 14 shows a state in which a positive type photosensitive resin 451 that constitutes the first lens is applied to a glass substrate 500, and the photosensitive resin 451 is exposed using an exposure mask 400. The arrow in FIG. 14 is the light for exposure. FIG. 15 is a graph showing the light transmittance of the exposure mask 400. The vertical axis is the transmittance and the horizontal axis is the position. The light transmittance profile is symmetrical with the cross-sectional shape of the first lens. That is, since it is a positive photosensitive resin, it has a profile that allows a large amount of exposure to a portion to be thinned.

FIG. 16 is a cross-sectional view showing the shape of the first lens 45 after development. The developed first lens 45 is formed on the glass substrate 500. That is, the portion corresponding to the apex of the convex lens is hardly exposed to light, so that it is insoluble in the developing solution. It will melt away. As a result, the lens shape is as shown in FIG. After that, as shown in FIG. 17, when the glass substrate 500 is removed, the first lens 45 is completed.

As shown in FIG. 10, since the partition plate 70 is a combination of thin white PET plates in a grid shape, its shape is unstable. Therefore, as shown in FIG. 18, it is efficient to first fix the partition plate 70 to the first lens 45 with an adhesive or the like, and then combine it with the light source substrate 61 side on which the LED 60 and the protective film 63 are arranged. ..

FIG. 18 is a cross-sectional view showing a state in which the partition plate 70 attached to the first lens 45 is arranged on the protective film 63 on the light source substrate 61 side. In FIG. 18, the LED 60 is mounted on the light source substrate 61, and the light source substrate 61 is covered with a protective film 63 except for the LED. The protective film 63 also has a role as a reflective film. In FIG. 18, the plane of the LED is rectangular, and the width lx of the LED is 0.1 mm to 0.5 mm. In this embodiment, an LED having a square plane is used, but an LED having a rectangular plane may be used. The height lh of the LED is, for example, 0.5 mm. The thickness fh of the protective film is, for example, 0.3 mm. The light emitting portion of the LED 60 exists on the upper side of the upper surface of the protective film 63, that is, on the first lens 45 side.

19 and 20 are cross-sectional views of the light source portion. FIG. 19 is a configuration of a light source portion according to Comparative Examples 1 and 2, and FIG. 20 is a configuration of a light source portion according to the first embodiment. The LED configuration is the same in both FIGS. 19 and 20. The difference between FIGS. 19 and 20 is that in FIG. 19, the transparent resin 62 is formed so as to cover the LED 60, whereas in FIG. 20, the white protective film 63 is formed so as to cover the portion other than the LED 60. That is.

FIG. 19 is a detailed cross-sectional view showing an LED 60, a transparent resin 62, electrodes, and the like. The LED 60 is a blue LED. In FIG. 19, the light source substrate 61 is made of, for example, an epoxy resin. On the light source substrate 61, an electrode pad 612 connected to the anode 601 of the LED 60 and an electrode pad 613 connected to the cathode 602 of the LED 60 are formed of metal. Various other wirings are formed on the light source substrate 61, but they are omitted in FIG. The LED 60 is flip-chip bonded to the

electrode pads

612 and 613 of the light source substrate 61. That is, the

terminal electrodes

601 and 602 of the LED 60 and the

electrode pads

612 and 613 of the light source substrate 61 face each other and are connected via the solder 615. The LED 60 is formed by joining a p-type semiconductor and an n-type semiconductor, but in reality, various layers are formed in order to increase the luminous efficiency.

The LED 60 is covered with a transparent resin 62 and protected. When a voltage is applied to the LED, it emits light at the boundary between the p-type layer and the n-type layer. Light is emitted not only in the upward direction but also in the lateral direction. This situation is indicated by an arrow in FIG. The problem with the configuration in FIG. 19 is that the light emitted laterally is incident on adjacent segments. Therefore, accurate local dimming cannot be performed.

FIG. 20 is a cross-sectional view of the light source portion in the first embodiment. The configuration of the light source substrate 61 and the configuration of the LED 60 in FIG. 20 are the same as those described in FIG. The difference between FIG. 20 and FIG. 19 is that in FIG. 20, the transparent resin that covers the entire LED 60 does not exist and does not cover the LED 60, but the white protective film 63 that covers the electrodes and the like formed on the light source substrate 61. Is formed. The joint portion between the p-type layer and the n-type layer, which is the light emitting portion of the LED 60, is not covered by the protective film 63.

Therefore, the light from the LED 60 will be emitted directly into the space. As shown by the arrow in FIG. 20, the light from the LED 60 is also emitted in the lateral direction, but this light is reflected by the partition plate 70 arranged at the boundary of the segment as shown in FIG. 9, and is therefore adjacent. It does not enter the segment. The light reflected from the first lens 45 and the partition plate 70 and heading downward is reflected by the white protective film 63 having a role as a reflective layer, and is directed to the first lens 45 side again. As described above, the light source shown in FIG. 20 has excellent light utilization efficiency of the LED 60 and has a configuration in which light does not leak to adjacent segments, so that accurate local dimming is possible.

As described above, in the first embodiment, the light emitted from the LED 60 can be suppressed from leaking to the adjacent segment by the structure of the light source substrate and the partition plate 70. Further, since the first lens 45 arranged on the partition plate 70 converges in the direction of the display panel, light leakage to the adjacent segment can be further reduced.

FIG. 21 is a cross-sectional view of the backlight in Example 2, and FIG. 22 is a plan view including the second lens 80 used in Example 2 and the LED 60 as a light source. In FIG. 21, the configuration from the first lens 45 to the prism sheet 52 is the same as that of the first embodiment. Further, the blue LED 60 as a light source is the same as that in the first embodiment. The feature of the second embodiment is that the second lens 80 is used instead of the partition plate 70 in order to prevent light leakage to the adjacent segment. It is desirable that the cross-sectional shape of the second lens 80 is convex outward and conforms to a hyperbola.

In FIG. 21, a recess 81 is formed on the lower surface of the second lens 80, and the tip of the LED 60 is fitted into the recess 81. In FIG. 21, the light emitted from the LED 60 is incident on the second lens 80. Here, the second lens 80 forms a concave lens with respect to the LED 60. Therefore, it is possible to improve the incident efficiency of light from the LED 60 to the second lens 80. The light incident on the second lens 80 from the LED 60 spreads once, but is totally reflected at the interface of the second lens 80 and heads toward the first lens 45. This situation is indicated by an arrow in FIG. Therefore, the light from the LED does not leak to the adjacent pixels.

As shown in FIG. 21, the cross-sectional shape of the second lens 80 is a shape according to a hyperbola, but the planar shape is a circle as shown in FIG. 22A and a square shape as shown in FIG. 22B. There are cases. Further, as shown in FIGS. 22A and 22B, the concave portion 81 formed on the lower surface of the second lens 80 may have a circular shape or a square shape. In FIGS. 22A and 22B, the boundaries between the segments are shown by dotted lines, but this is for convenience only and there are no actual boundaries. However, unlike the cases of FIGS. 4 and 6, the light from the LED 60 is confined in the second lens 80, so that the light does not leak to the adjacent segment. The planar shape of the second lens 80 and the recess 81 is not limited to a circle or a square, but may be a polygon.

23 to 26 are sectional views showing a process of manufacturing the second lens 80. In FIG. 23, the photosensitive resin 801 that constitutes the second lens 80 is applied to the glass substrate 500, and this is exposed using the exposure mask 400. The arrow in FIG. 23 represents the exposure light. As for the second lens 80, for example, a positive photosensitive resin made of acrylic resin, silicone resin, polycarbonate or the like is used.

FIG. 24 is a graph showing the light transmittance of the exposure mask 400. The vertical axis is the transmittance and the horizontal axis is the position. The light transmittance profile is symmetrical with the cross-sectional shape of the second lens 80. That is, since it is a positive photosensitive resin, it has a profile that allows a large amount of exposure to a portion to be thinned.

FIG. 25 is a cross-sectional view showing the shape of the second lens 80 after development. That is, since a positive photosensitive material is used, the shape of the second lens 80 is substantially symmetrical to the transmittance profile of the exposure mask shown in FIG. 24. Then, as shown in FIG. 26, the glass substrate 500 is removed to complete the second lens 80.

As shown in FIG. 26, the second lens 80 is not separated individually, but is connected at a portion having a large aperture. However, since the plate thickness of the connected portion is small, the rigidity of the second lens array 80 as a whole is not high. Therefore, it is rational to attach the first lens 45 and the second lens 80 to each other and then attach them to the light source substrate 61 side.

FIG. 27 is a cross-sectional view showing a state in which the configuration in which the first lens 45 and the second lens 80 are bonded is arranged on the protective film 63 on the first substrate side 61 side. The LED 60 arranged on the light source substrate 61 is housed in the recess 81 of the second lens 80. The other configurations on the light source substrate 61 side and the configurations of the LED 60 are the same as those described with reference to FIG. 20 of the first embodiment.

As described above, in the second embodiment, by using the two

lenses

45 and 80 formed of the resin, the light from the LED 60 is confined in the lens, and the light converged by the lens effect is diffused by the color conversion sheet. Since it is incident on an optical sheet group composed of sheets or the like, it is possible to effectively prevent light leakage to adjacent segments.

FIG. 28 is a cross-sectional view showing the configuration of the backlight according to the third embodiment. The feature of the third embodiment is that the first lens 45 and the second lens 80 in the second embodiment are integrated to form a convex lens 85. It is the same as in Example 2 that the concave portion 81 is formed on the lower surface of the convex lens 85 to accommodate the LED 60. The planar shape of the convex lens 85 is the same as that of FIG. 22 in the second embodiment. The operation in the third embodiment is the same as that described in the second embodiment. However, in the third embodiment, since the first lens 45 and the second lens 80 in the second embodiment are integrally formed, the step of bonding the first lens 45 and the second lens 80 can be omitted.

29 to 33 are cross-sectional views showing the process of forming the convex lens 85. In FIG. 29, the base layer 510 for forming the lens curved surface of the first lens 45 on the convex lens 85 is formed on the glass substrate 500. The base layer 510 can also be formed by photolithography using a resin. That is, it can be manufactured in the same process as the manufacturing of the first lens 45 in the first embodiment. However, the curved surface is opposite to that of the first lens of the first embodiment. The base layer 510 can be used repeatedly if the resin constituting the convex lens 45 formed on the base layer 510 and a material having good releasability are used.

FIG. 30 is a cross-sectional view showing a state in which the resin 801 which is the material of the convex lens 85 is applied on the base layer 510. FIG. 31 is a cross-sectional view showing a state in which the resin 801 which is the material of the convex lens 85 is exposed by using the exposure mask 400. In FIG. 31, the arrow represents the light to be exposed. The light transmittance of the exposure mask 400 is the same as that of FIG. 24 in Example 2.

FIG. 32 is a cross-sectional view showing the shape of the convex lens 85 after development. The shape of the convex lens 85 after development is the same as that of the combination of the first lens 45 and the second lens 80 in the second embodiment. After that, as shown in FIG. 33, the glass substrate 500 and the base layer 510 formed on the glass substrate 500 are separated from the convex lens 85. If the convex lens 85 and a material having good releasability are used for the base layer 510, the combination of the glass substrate 500 and the base layer 510 can be repeatedly used.

Combining the convex lens 85 with the light source substrate 81 on which the LED 60 and the like are formed is the same as in FIG. 27 in the second embodiment. As described above, in the third embodiment, the first lens 45 and the second lens 80 in the second embodiment are formed at the same time, so that the manufacturing process can be simplified. The effect of Example 3 is the same as that of Example 2.

FIG. 34 is a cross-sectional shape of the backlight of the fourth embodiment. In FIG. 34, a reflective layer 91 is formed on the inner wall of the through hole formed in the partition resin 90 that partitions the segments, thereby reliably preventing the light from the LED 60 from leaking to the adjacent segment. The curved surface of the reflective layer 91 has a shape conforming to a hyperbola, and the reflected light is efficiently directed to the first lens 45 side. In other words, the partition resin 90 is formed with through holes having an inner wall having a shape conforming to a hyperbola, and as a result, an efficient reflective layer 91 is formed.

The light reflected by the reflective layer 91 and incident on the first lens 45 is converged by the first lens 45 and incident on an optical sheet group such as a color conversion sheet. Therefore, in the optical sheet group, light leakage to adjacent segments is further suppressed. In FIG. 34, from the first lens 45 to the upper prism sheet 52 is the same as in FIG. 9 of the first embodiment.

35A and 35B are plan views showing the reflective layer 91 and the partition resin 90. FIG. 35A is a case where the plan view of the reflective layer 91 is a circle, and FIG. 35B is a case where the plan view of the reflective layer 91 is a square. The reflective layer 91 is formed by coating the inner wall of the through hole formed in the partition resin 90 with a material having a high reflectance such as metal by vapor deposition, sputtering, or the like. As the metal, for example, Al or an alloy thereof is suitable. The planar shape of the through hole formed in the partition resin 90 is a circle in FIG. 35A and a square in FIG. 35B. The dotted lines shown in FIGS. 35A and 35B indicate the boundaries of the segments for convenience, but such lines do not actually exist. However, since the light from the LED 60 is confined in the through hole having the reflective layer 91, the light does not leak to the adjacent segment.

36 to 39 are cross-sectional views showing the process of forming the reflective layer 91 in the fourth embodiment. FIG. 36 is a cross-sectional view showing a state in which the material 901 of the partition resin 90 applied on the glass substrate 500 is exposed through the exposure mask 400. Arrows in FIG. 36 indicate light for exposure. As the material 901 of the partition resin 90, for example, a positive type material is used. As the light transmittance profile of the exposure mask 400, a pattern forming a normal through hole may be applied.

FIG. 37 is a cross-sectional view showing a state in which a through hole 92 is formed in the material 901 of the partition resin 90 to form the partition resin 90. FIG. 38 is a cross-sectional view showing a state in which a metal as a reflective material is formed in a portion of a through hole 92 of a partition resin 90 by vapor deposition or sputtering in order to form a reflective layer 91 via a vapor deposition mask 450. Is. Arrows in FIG. 37 indicate the orientation of the deposited atoms. The vapor deposition mask 450 is for preventing the reflective layer 91 from being attached to the upper surface of the partition resin 90. However, if there is no problem even if the reflective layer 91 is formed on the upper surface of the partition resin 90, the vapor deposition mask 450 can be omitted.

After that, as shown in FIG. 39, if the glass substrate 500 is removed from the compartment resin 90, the compartment resin 90 on which the reflective layer 91 is formed is completed. If the reflective layer material 91 adhering to the glass substrate 500 is removed by etching, the glass substrate 500 can be used repeatedly.

FIG. 40 is a cross-sectional view showing a state in which a partition resin 90 on which a reflective layer 91 is formed is bonded to a first lens 45 separately formed, and a light source substrate 61 having an LED 60 or the like is combined. The LED 60 will be fitted into a small hole of the through hole 92 formed in the partition resin 90. The structures of the light source substrate 61, the LED 60, and the like in FIG. 40 are the same as those described in the first embodiment.

As described above, in the fourth embodiment, the reflective layer 91 is used to prevent the light from the LED 60 from leaking to other segments. Further, since the light from the reflective layer 91 is converged by the first lens 45, it is possible to reduce the diffusion of light from the optical sheet group arranged above the first lens 45 to the adjacent segment.

FIG. 41 is a cross-sectional view showing the fifth embodiment, and FIG. 42 is a plan view showing the partition resin 90 and the LED 60 in the fifth embodiment. Example 5 is a modification of Example 4, and the reflective layer made of metal is not formed on the inner wall of the through hole 92 formed in the partition resin 90. Instead, the partition resin 90 itself is formed of a resin having a high reflectance. For example, white resins such as white PET and polyester have high reflectance.

As shown in FIG. 41, since the cross-sectional shape of the inner wall of the through hole 92 of the partition resin 90 is a curve conforming to a hyperbola, much light from the LED 60 is reflected by the side wall of the through hole 92 and is parallel. It becomes close to light and is incident on the first lens 45. The configuration above the first lens 45 in FIG. 41 is the same as that of the first embodiment or the fourth embodiment.

FIG. 42 is a plan view showing the shapes of the partition resin 90 and the through hole 92. As shown in FIG. 42, the planar shape of the through hole 92 is a circle. The LED 60 is arranged in the small hole portion of the through hole 92. The dotted line shown in FIG. 42 indicates the boundary of the segment for convenience, but such a line does not actually exist. However, since the light from the LED 60 is confined in the through hole 92, the light does not leak to the adjacent segment.

The method for forming the through hole 92 of the compartment resin 90 in FIG. 41 is the same as that described in the fourth embodiment. That is, in the manufacturing method of Example 4, the formation of the metal film for the reflective layer 91 is omitted. Therefore, in the fifth embodiment, the manufacturing cost of the backlight can be reduced as compared with the case of the fourth embodiment. The operation of Example 5 is that in Example 5, the light from the LED 60 is reflected by the inner wall of the through hole 92 of the partition resin 90 formed of the reflective resin and directed toward the first lens 45, except that the light is directed to the first lens 45. Is the same as.

Although the planar shape of the through hole 92 shown in FIG. 42 is a circle, the present embodiment is not limited to this, and the planar shape of the through hole 92 may be a square or a polygon.

Examples 1 to 5 are cases where a blue LED 60 is used as a light source. However, the present invention can be similarly applied when the white LED 65 is used as the light source. FIG. 44 is a cross-sectional view showing an example of the sixth embodiment. FIG. 44 is different from FIG. 9 of the first embodiment in that the light source is a white LED 65 and the optical sheet group does not include a color conversion sheet. That is, since the light source is originally white, there is no need to perform color conversion.

FIG. 43 is a plan view including the partition plate 70 in FIG. 44 and the white LED 65 as a light source. The configuration of FIG. 43 is the same as that of FIG. 8 of the first embodiment except that the light source is the white LED 65.

FIG. 46 is a cross-sectional view showing the configuration of the white LED 65 used in the sixth embodiment and its surroundings. The structure of FIG. 46 is the same as that of FIG. 20, except that the LED is a white LED 65. FIG. 45 is a configuration of the white LED 65 and its surroundings used in Comparative Example 2 shown in FIGS. 6 and 7. In FIG. 45, the entire white LED 65 is covered with the transparent resin 62. As described with reference to FIG. 19, in the structure of FIG. 45, there arises a problem that light leaks to adjacent pixels through the transparent resin 62. In that respect, since the configuration of FIG. 46 does not use a transparent resin as described with reference to FIG. 20, such a problem does not occur.

43 and 44 are examples of the case where the white LED 65 is used for the configuration of the first embodiment, but the white LED 65 can be similarly applied to the second to fifth embodiments.

In the above embodiment, the number of blue LEDs 60 or white LEDs 65 is one per segment, but even when a plurality of blue LEDs 60 or white LEDs 65 are present, the present invention can be applied by modifying the second lens, the partition resin, the reflective layer, or the like. Can be done.

Further, even when a light guide plate is used instead of the first lens, the configuration of the second lens, the partition resin, the reflective layer, the light source substrate, or the like can be applied, and the effect can be obtained. ..

10 ... Display panel, 11 ... Scanning line, 12 ... Video signal line, 13 ... Pixel, 14 ... Display area, 15 ... Terminal area, 16 ... Sealing material, 17 ... Flexible wiring board, 20 ... Backlight, 30 ... Light source, 40 ... light guide plate, 45 ... first lens, 50 ... optical sheet group, 60 ... blue LED, 61 ... light source substrate, 62 ... transparent resin, 63 ... white protective film, 65 ... white LED, 70 ... partition plate, 80 ... 2nd lens, 81 ... concave, 90 ... partition resin, 91 ... reflective layer, 92 ... through hole, 100 ... TFT substrate, 101 ... lower polarizing plate, 200 ... opposed substrate, 201 ... upper polarizing plate, 300 ... liquid crystal, 400 ... exposure mask, 451 ... resin for first lens, 450 ... vapor deposition mask, 500 ... glass substrate, 510 ... base layer, 601 ... terminal electrode, 602 ... terminal electrode, 612 ... electrode pad, 613 ... electrode pad, 615 ... solder , 801 ... Resin for the second lens, 901 ... Material for compartment resin

Claims

A display device having a display panel and a backlight.
The backlight has a light source and a group of optical sheets.
The light source has a light source substrate and LEDs arranged on the light source substrate.
The light source is divided into segments when viewed in a plane.
At least one LED is present in the segment.
The light source substrate is covered with a protective film except for the LED, and the light source substrate is covered with a protective film.
The segment is partitioned in a wall shape by a partition plate made of resin.
The partition plate is placed on the protective film, and the partition plate is placed on the protective film.
A display device characterized in that a convex lens is formed between the partition plate and the optical sheet group.
The display device according to claim 1, wherein the light emitting portion of the LED is located closer to the optical sheet group than the upper surface of the protective film.
The display device according to claim 1, wherein the area surrounded by the partition plate is a space.
The display device according to claim 1, wherein the partition plate is made of white PET resin.
The display device according to claim 1, wherein the protective film is made of a white resin.
The display device according to claim 1, wherein the LED is a blue LED, and the optical sheet group includes a color conversion sheet.
A display device having a display panel and a backlight.
The backlight has a light source and a group of optical sheets.
The light source has a light source substrate and LEDs arranged on the light source substrate.
The light source is divided into segments when viewed in a plane.
At least one LED is present in the segment.
The light source substrate is covered with a protective film except for the LED, and the light source substrate is covered with a protective film.
In the segment, a second lens is formed on the protective film and so as to surround the LED.
The aperture of the second lens is larger on the optical sheet group side than on the LED side.
A display device characterized in that a first lens is formed between the second lens and the optical sheet group.
The display device according to claim 7, wherein the outer cross-sectional shape of the second lens is convex outward.
The display device according to claim 7, wherein the second lens is a circle when viewed in a plane.
The display device according to claim 7, wherein the upper surface of the second lens is a flat surface, and the first lens is arranged on the flat surface.
The display device according to claim 7, wherein the curved surface of the second lens surrounding the LED forms a concave lens.
The display device according to claim 7, wherein the first lens and the second lens are integrated.
The display device according to claim 7, wherein the light emitting portion of the LED is located closer to the optical sheet group than the upper surface of the protective film.
The display device according to claim 1, wherein the protective film is made of a white resin.
A display device having a display panel and a backlight.
The backlight has a light source and a group of optical sheets.
The light source has a light source substrate and LEDs arranged on the light source substrate.
The light source is divided into segments when viewed in a plane.
At least one LED is present in the segment.
The light source substrate is covered with a protective film except for the LED, and the light source substrate is covered with a protective film.
The segments are partitioned by a compartment resin and
Through holes are formed in the partition resin, and through holes are formed.
The cross-sectional shape of the through hole is an outwardly convex curved surface.
When viewed in a plane, the diameter of the through hole is larger on the optical sheet group side than on the light source substrate side.
A display device characterized in that a convex lens is formed between the partition resin and the optical sheet group.
The display device according to claim 15, wherein the shape of the through hole is a circle when viewed in a plane.
The display device according to claim 15, wherein the compartment resin is made of an opaque white resin.
The display device according to claim 17, wherein a reflective layer made of metal or alloy is formed on the inner wall of the through hole.
The display device according to claim 15, wherein the through hole and the convex lens correspond to each other.
The display device according to any one of claims 1 to 19, wherein the display panel is a liquid crystal display panel.