JP2008262012A - Optical member and backlight unit, and display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical member and a backlight unit, and a display device, wherein production is attained at a low cost and luminance on front surface is drastically increased by suppressing leakage of light in oblique directions. <P>SOLUTION: The optical member has a lenticular lens member 3 which is formed by arranging a plurality of convex lenses 2 each having an arcuate cross-section in a matrix on a front surface, a light-absorbing layer 4 arranged on a back surface of the lenticular lens member 3 and a light-reflecting layer 5 arranged on a back surface of the light-absorbing layer 4. In the light-absorbing layer 4 and the light-reflecting layer 5, optical windows 6 are opened directly below ridge apexes of the corresponding convex lenses 2, wherein the optical windows 6 constitutes an imaging optical system where irradiation light emitted from a backlight part which is set as a focal position, passes through the optical windows 6 and exits from the convex lenses 2 as parallel rays of light. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical member having a high front luminance and suitable for a liquid crystal display device, a backlight unit including the same, and a display device.

  Liquid crystal display devices for displaying images are widely used in mobile phones, PDAs, ATMs (automated teller machines), personal computer displays, and the like. This liquid crystal display device uses a backlight unit that emits light from the back side of the liquid crystal display panel to increase the brightness of the display screen.

  In recent years, there is a demand to improve visibility from the front of the screen and limit visibility from the oblique side of the screen according to the usage environment of the liquid crystal display device. For example, on a liquid crystal display of a mobile phone or an operation screen of an ATM such as a bank, there is a demand for preventing a person from peeping at the displayed image or information from the side while using it.

  As a peep prevention sheet or film used for such a purpose, for example, in Patent Document 1, a white layer, a black layer, a transparent layer, an antiglare for an illuminated display body of a silicone rubber in which a black layer is repeatedly arranged A sheet has been proposed. In this antiglare sheet, light diffusion is suppressed by a light blocking effect by the black layer. Patent Document 2 proposes a peep prevention body for an information display body having an antiglare layer in which a plurality of transparent silicone rubber sheets and colored silicone rubber sheets are alternately arranged and integrated. In this peep prevention body, the anti-glare effect of the anti-glare layer prevents a third party from peeping from the side.

  Further, in Patent Document 3, a translucent resin base material that is used in place of a prism sheet of a backlight and has a convex lens shape continuously formed on one surface, and a translucent resin base. An optical member sheet having a reflective layer formed in a region including a boundary of a convex lens-shaped object on the other surface of the material has been proposed. In this optical member sheet, light rays are concentrated on the front of the screen by a plurality of convex lens shaped objects to improve the screen brightness.

Japanese Patent Laid-Open No. 5-94731 JP 2003-131202 A JP 2006-145653 A

However, the following problems remain in the conventional technology.
That is, in the techniques of Patent Documents 1 and 2, since a plurality of colored layers (colored sheets) and transparent layers (transparent sheets) are stacked and sliced in a direction perpendicular to the stacking direction, there is a disadvantage that the manufacturing cost is high. is there. In addition, since the light is shielded by the colored layers arranged at a predetermined interval, the light traveling obliquely between the adjacent colored layers causes leakage light in an oblique direction other than the front. Furthermore, in the technique of Patent Document 3, light beams are concentrated on the front side with a plurality of convex lens-shaped objects. However, like a normal plasma sheet, the light incident obliquely on the sheet changes its traveling direction to the front side. Therefore, there is a problem in that a significant improvement in front luminance cannot be expected compared to a normal plasma sheet and leakage light in an oblique direction is generated.

  The present invention has been made in view of the above-described problems, and can be manufactured at a low cost, and an optical member and a backlight unit capable of significantly improving front luminance by suppressing light leakage in an oblique direction. An object is to provide a side-by-side display device.

  The present invention employs the following configuration in order to solve the above problems. That is, the optical member of the present invention is arranged in parallel to the surface side of the surface light source and has a lenticular lens member formed by arranging a plurality of half-cylindrical convex lenses on the surface, and the back surface of the lenticular lens member. A light absorption layer portion disposed on the back surface of the light absorption layer portion, and the light absorption layer portion and the light reflection layer portion, with the surface light source as a focal position. Optical windows constituting an imaging optical system that converts the parallel light at the convex lens portion through the irradiation light from the surface light source are respectively opened directly below the ridge line top of the convex lens portion.

In this optical member, an optical window that forms an imaging optical system in which a surface light source is a focal position and light is radiated from the surface light source is converted into parallel light by a half-cylindrical convex lens portion on the light absorption layer portion and the light reflection layer portion. However, the irradiation light from the surface light source such as the backlight portion is condensed by the imaging optical system of the optical window and the convex lens portion to be parallel light. Therefore, leakage light can be suppressed and the front luminance can be greatly improved. In addition, since the light reflection layer portion blocks the incidence of oblique light other than in the front direction and the light absorption layer portion suppresses light scattering, leakage light in an oblique direction other than the front direction can be prevented. Therefore, the luminance in an oblique direction other than the front direction can be extremely reduced. In other words, light in the front direction from directly below the convex lens portion extending in a straight line is transmitted as it is, and oblique light from other than directly below the convex lens portion is blocked, so that light that is blocked according to the arrangement direction of the convex lens portions is blocked. The direction can be set.
Furthermore, by providing the light absorption layer part, it is possible to absorb the light reflected by the boundary surface of the convex lens part and incident on the light absorption layer part, and also in this respect, a high leakage light prevention effect can be obtained.
In addition, since the process of laminating | stacking many layers and slicing like the prior art is unnecessary, it can manufacture at low cost. The lenticular lens member is a so-called micro lenticular lens array in which minute halved cylindrical convex lens portions are one-dimensionally arranged, and is lower than a micro lens array in which minute hemispherical convex lens portions are two-dimensionally arranged. Cost, and the entire optical member can be manufactured inexpensively.

  The backlight unit of the present invention includes the above-described optical member of the present invention and a backlight unit that is the surface light source that emits irradiation light toward the optical member. In other words, the backlight unit includes a backlight unit as a surface light source that emits irradiation light toward the optical member. Therefore, the irradiation light toward the optical member is efficiently collected and the backlight has a high front luminance. You can get the light.

  The backlight unit of the present invention includes a light guide plate arranged in parallel to the optical member, a light source arranged at an end of the light guide plate to emit light into the light guide plate, the light guide plate, And a prism sheet that is disposed between the optical member and emits light incident from the light guide plate toward the optical member. That is, in this backlight unit, since the incident light from the light source passes through the prism sheet via the light guide plate, the incident light becomes irradiation light in the traveling direction toward the optical member by the prism sheet. Therefore, it is possible to efficiently emit the irradiation light toward the optical window of the optical member, and it is possible to improve the front luminance by increasing the light collection degree.

  The display device of the present invention includes an image display panel and the backlight unit of the present invention disposed on the back side of the image display panel. That is, since the display device includes the backlight unit of the present invention, an image having high front luminance is obtained by irradiating the image display panel with the irradiation light of the backlight condensed in the front direction. Display is possible. In particular, the effect of preventing peeping from the left and right can be obtained by arranging the optical member so as to increase the light collecting degree in the left-right direction among the upper, lower, left and right sides of the image display panel.

  In the display device of the present invention, the image display panel is a liquid crystal display panel. That is, since this display device is a liquid crystal display device using a liquid crystal display panel, it is possible to reduce the thickness and weight and reduce the cost, and to obtain a liquid crystal display having high front luminance.

The present invention has the following effects.
That is, according to the optical member and the backlight unit according to the present invention, the optical window constituting the imaging optical system in which the surface light source is the focal position and the parallel light is generated by the half-cylindrical convex lens portion through the irradiation light from the surface light source. However, since the irradiation light from the surface light source is condensed by the optical window and the imaging optical system of the convex lens part to be parallel light, the leakage light is reduced. It is possible to significantly improve the front luminance. Moreover, the light absorption layer portion and the light reflection layer portion can suppress leakage light in an oblique direction other than the front direction. Therefore, in the display device equipped with the optical member and the backlight unit of the present invention, high luminance display with high directivity to the front is possible by high front luminance and prevention of leakage light in an oblique direction. It is suitable for a liquid crystal display of a cellular phone, an ATM operation screen, etc. for peep prevention.

  Hereinafter, an optical member, a backlight unit, and a display device according to an embodiment of the present invention will be described with reference to FIGS. In each drawing used in the following description, the scale is appropriately changed to make each member a recognizable size.

  As shown in FIGS. 1 and 2, the optical member 1 in the present embodiment is in the form of a sheet, a film, or a plate, and a plurality of halved cylindrical convex lens portions 2 are arranged in an array on the surface. The formed lenticular lens member 3, the light absorption layer portion 4 disposed on the back surface of the lenticular lens member 3, and the light reflection layer portion 5 disposed on the back surface of the light absorption layer portion 4 are provided. In the light absorption layer portion 4 and the light reflection layer portion 5, optical windows 6 are respectively opened immediately below the ridgeline top of the convex lens portion 2.

  The lenticular lens member 3 is in the form of a sheet, film or plate formed of a light transmissive resin such as epoxy resin, polyester, polycarbonate, polyvinyl chloride or the like. The lenticular lens member 3 is a so-called micro lenticular lens array in which a plurality of convex lens portions 2 having a half columnar shape, that is, a substantially semicircular cross section and extending in one direction are arranged parallel to each other on the surface and are integrally molded. . The material (refractive index and the like) and thickness of the lenticular lens member 3 are appropriately set depending on the shape, lens characteristics, strength, and the like of the convex lens portion 2.

The light absorption layer 4 is a black layer of carbon or the like laminated on the back surface of the lenticular lens member 3.
The light reflection layer 5 is a metal plate, film, foil, or the like having a light reflection function of silver or white laminated on the back surface of the light absorption layer 4. In this embodiment, a silver vapor deposition film is provided. Film layer. Note that an aluminum metal vapor deposition film or the like may be employed instead of the silver vapor deposition film.

The backlight unit 7 of the present embodiment includes the optical member 1 and a backlight unit 8 that is a surface light source that emits irradiation light toward the optical member 1.
The backlight unit 8 includes a light guide plate 9 disposed in parallel to the optical member 1, a light source 10 disposed at an end of the light guide plate 9 to emit light into the light guide plate 9, the light guide plate 9, and the optical member. 1 and a prism sheet 11 that emits light incident from the light guide plate 9 as an upward irradiation light toward the optical member 1 and a reflection sheet 12 disposed on the lower surface of the light guide plate 9. I have.

  The optical window 6 is set so as to constitute an imaging optical system in which the backlight unit 8 which is a surface light source is a focal position and the light beam from the backlight unit 8 is converted into parallel light by the convex lens unit 2. The optical window 6 is formed in a linear shape (slit shape) with a certain width along the convex lens portion 2 at a position facing each convex lens portion 2, and the width is the distance from the backlight portion 8, It is determined as appropriate by the imaging optical system corresponding to the size and shape of the convex lens portion 2. Further, the center line of each optical window 6 is arranged immediately below the top of the corresponding ridgeline of the convex lens part 2.

  The prism sheet 11 is a transparent sheet-like member for condensing light from the light guide plate 9 on the upper surface side, and has a prism portion 14 having a plurality of parallel ridge lines 14a on the rear surface side. Further, the optical axis of the light source 10 is set at a position where the optical axis is twisted with respect to the ridge line 14a of the prism portion 14 in the prism sheet 11, and in particular, the direction of the prism portion 14 as a direction in which high directivity is obtained. It is set parallel to the direction orthogonal to the ridge line 14a.

The light guide plate 9 is made of transparent polycarbonate resin, acrylic resin, or the like.
The reflection sheet 12 is a metal plate, film, foil or the like having a light reflection function, and in this embodiment, a film provided with an aluminum metal vapor deposition film is employed.

The light source 10 is a plurality of white LEDs arranged at the side end of the light guide plate 9. This white LED is, for example, a semiconductor light emitting element on a substrate sealed with a resin material. As a semiconductor light emitting element, for example, a blue (wavelength λ: 470 to 490 nm) LED element or ultraviolet light (wavelength λ: less than 470 nm). An LED element is formed by laminating a plurality of semiconductor layers of a gallium nitride compound semiconductor (for example, an InGaN compound semiconductor) on an insulating substrate such as a sapphire substrate.
Further, the resin material for sealing the semiconductor light emitting element is mainly composed of a silicone resin and, for example, a YAG phosphor is added. This YAG phosphor converts white light or ultraviolet light from a semiconductor light emitting element into yellow light and generates white light by a color mixing effect. Various white LEDs other than those described above can be used.

The display device of the present embodiment is a liquid crystal display device applied to, for example, a mobile phone, a PDA, or an ATM liquid crystal display, and is disposed on the liquid crystal display panel (image display panel) 13 and the back side of the liquid crystal display panel 13. The backlight unit 7 is also provided.
In the present embodiment, the screen side of the liquid crystal display panel 13 and the light emission surface side of the backlight unit 7 are described as the surface side or the upper surface side.

  The liquid crystal display panel 13 is a transmissive or transflective liquid crystal display panel. For example, the liquid crystal display panel 13 of the present embodiment is a transflective type, and a panel body 25 in which liquid crystal L is sealed with a sealing material 24 in the gap between the upper substrate 22 and the lower substrate 23, and light is transmitted to the lower surface side thereof. And a transflective plate 26 having both functions of light and light reflectivity. As the liquid crystal L, a TN liquid crystal, an STN liquid crystal, or the like is used. The upper substrate 22 includes an upper transparent substrate 22a made of glass or the like, an upper transparent electrode 22b made of an ITO film provided on the lower surface of the upper transparent substrate 22a, and a transparent polyimide resin film provided on the lower surface of the upper transparent electrode 22b. And the like, and an upper polarizing film 22d provided on the upper surface of the upper transparent substrate 22a.

The lower substrate 23 includes a lower transparent substrate 23a made of glass or the like, a lower transparent electrode 23b made of an ITO film provided on the upper surface of the lower transparent substrate 23a, and a transparent polyimide resin film provided on the upper surface of the lower transparent electrode 23b. And the like, and a lower polarizing film 23d provided on the lower surface of the lower transparent substrate 23a.
As the transflective plate 26, an aluminum metal vapor-deposited film sheet or a reflective polarizing plate formed so as to have transparency is used. In the gap between the upper substrate 22 and the lower substrate 23, spacers (not shown) made of silica balls, plastic balls or the like are dispersed and secured to ensure a predetermined gap.

  In the optical member 1 and the backlight unit 7 of the present embodiment, as shown in FIG. 4, the irradiation light from the backlight unit 8 is collected by the convex lens unit 2 through the optical window 6 functioning like a slit. Thus, the light is collimated and emitted toward the upper liquid crystal display panel 13.

  Next, simulation results of the light directivity characteristics of the optical member, the backlight unit, and the display device according to the present embodiment will be described with reference to FIGS.

As a result of the simulation of the light directivity characteristics in the backlight unit 7 including the optical member 1 and the backlight unit 8 according to the present embodiment, as shown in FIG. 5, a surface orthogonal to the extending direction of the convex lens unit 2 (see FIG. 5). It can be seen that the medium ZY plane) has a very high directivity with respect to the front surface. In contrast, FIG. 6 shows the result of a similar simulation performed using the technique described in Patent Document 1 as a comparative example.
As can be seen from FIGS. 5 and 6, in the present embodiment, it can be seen that a narrower light directivity is obtained on the surface orthogonal to the extending direction of the convex lens portion 2 than in the comparative example.

  As described above, in the optical member 1 and the backlight unit 7 according to the present embodiment, the imaging unit that converts the parallel light into the half-cylindrical convex lens unit 2 through the irradiation light from the backlight unit 8 with the backlight unit 8 as the focal position. Since the optical windows 6 constituting the system are respectively opened immediately below the ridge-line top of the convex lens part 2, the irradiation light from the backlight part 8 is respectively lined by the imaging optical system by the convex lens part 2 and the optical window 6. The light is condensed into parallel light.

Therefore, it is possible to significantly improve the front luminance by suppressing the leakage light without reducing the light use efficiency. In addition, the light reflecting layer portion 5 blocks the incidence of oblique light other than the front direction, and the light absorption layer portion 5 suppresses light scattering, so that leakage light in an oblique direction other than the front direction can be prevented. The luminance in an oblique direction other than the front direction can be extremely reduced. That is, light from directly below the convex lens portion 2 extending in a straight line to the front direction is transmitted as it is, and oblique light from other than directly below the convex lens portion 2 is blocked, so that light is blocked according to the arrangement direction of the convex lens portions 2. The direction of the light to be set can be set.
Furthermore, by providing the light absorption layer part 4, it is possible to absorb the light reflected by the boundary surface of the convex lens part 2 and incident on the light absorption layer part 4, and also in this respect, a high light leakage prevention effect can be obtained. Can do.

  In addition, since the process of laminating | stacking many layers and slicing like the prior art is unnecessary, it can manufacture at low cost. Further, since the lenticular lens member 3 is a so-called micro lenticular lens array in which minute half-divided cylindrical convex lens portions 2 are arranged one-dimensionally, the microlens lens member 3 is a microlens array in which minute hemispherical convex lens portions are arranged two-dimensionally. The entire optical member can be manufactured at a low cost.

Therefore, in the backlight unit 7 of the present embodiment, since the irradiation light is emitted toward the optical member 1 by the backlight unit 8, the irradiation light toward the optical member 1 is efficiently condensed and the front luminance is increased. High backlight can be obtained.
That is, in the backlight unit 7, incident light from the light source 10 passes through the prism sheet via the light guide plate 9, and thus the incident light becomes irradiation light whose traveling direction is directed toward the optical member 1 by the prism sheet 11. Accordingly, the irradiation light can be efficiently incident on the optical window 6 of the optical member 1, and the degree of light collection can be increased and the front luminance can be further improved.

In the liquid crystal display device including the backlight unit 7 according to the present invention, the liquid crystal display panel 13 is irradiated with the irradiation light from the backlight unit 7 condensed in the front direction, thereby having high front luminance. Image display becomes possible.
For example, when the liquid crystal display panel 13 is vertically arranged, the lenticular is formed with the extending direction of the convex lens portion 2 being the vertical direction so as to block the light from the left and right diagonal directions of the liquid crystal display panel 13. By providing the lens member 3 and the optical member 1, it is possible to obtain a high front luminance and an effect of preventing peeping from the left and right directions.

  In addition, this invention is not limited to the said embodiment, A various change can be added in the range which does not deviate from the meaning of this invention.

For example, in the above embodiment, the light absorption layer portion 4 and the light reflection layer portion 5 are formed in a laminated state on the back side of the lenticular lens member 3, but the light absorption layer portion 4 and the light reflection layer portion 5 are separately provided. It may be formed as a body sheet-like or film-like member and arranged on the back surface of the lenticular lens member 3.
As described above, it is preferable to use a white LED for the light source 10, but a fluorescent tube of a linear light source may be adopted as the light source.

In the above embodiment, the liquid crystal display panel 13 is employed as the image display panel, but other image display panels may be used. For example, an image display panel such as electronic paper may be employed.
Various other configurations can be adopted as the backlight unit. For example, in the above embodiment, the diffusion sheet, which is a member that makes light emitted from the light guide plate more uniform, is omitted. However, a backlight unit in which this diffusion sheet is disposed on the light guide plate may be used. In the above-described embodiment, one prism sheet is used, but two prism sheets (two prism sheets in which the ridge lines of the prism portions are in a twisted relationship with each other) may be used.

1 is a cross-sectional view illustrating an optical member in an embodiment of an optical member, a backlight unit, and a display device according to the present invention. In this embodiment, it is a top view which shows an optical member. In this embodiment, it is a schematic sectional drawing which shows a backlight unit and a display apparatus. In this embodiment, it is an expanded sectional view of the principal part which shows a display apparatus. In this embodiment, it is a graph which shows the simulation result of a backlight directivity characteristic. It is a graph which shows the simulation result of a backlight directional characteristic in the prior art example which concerns on this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Optical member, 2 ... Convex lens part, 3 ... Lenticular lens member, 4 ... Light absorption layer part, 5 ... Light reflection layer part, 6 ... Optical window, 7 ... Backlight unit, 8 ... Backlight part (surface light source) , 9 Light guide plate, 10 Light source, 11 Prism sheet, 13 Liquid crystal display panel (image display panel)

Claims (5)

A lenticular lens member that is arranged in parallel to the surface side of the surface light source and is formed by arranging a plurality of half-cylindrical convex lens portions on the surface;
A light absorbing layer portion disposed on the back surface of the lenticular lens member;
A light reflecting layer portion disposed on the back surface of the light absorbing layer portion,
In the light absorption layer portion and the light reflection layer portion, an optical window that forms an imaging optical system in which the surface light source is a focal position and the parallel light is emitted from the surface light source through the light irradiated from the surface light source includes the convex lens. An optical member that is opened directly below the ridgeline top of each part. The optical member according to claim 1;
A backlight unit comprising: a backlight unit that is the surface light source that emits irradiation light toward the optical member. The backlight unit according to claim 2,
A light guide plate arranged in parallel with the optical member;
A light source arranged at an end of the light guide plate and emitting light into the light guide plate;
A backlight unit comprising: a prism sheet disposed between the light guide plate and the optical member and emitting light incident from the light guide plate toward the optical member. An image display panel;
A display device comprising: the backlight unit according to claim 2 disposed on a back surface side of the image display panel. The display device according to claim 4,
The display device, wherein the image display panel is a liquid crystal display panel.

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