JP2005043611A - Optical sheet, surface light source device, and transmission-type display device - Google Patents

Optical sheet, surface light source device, and transmission-type display device Download PDF

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Publication number
JP2005043611A
JP2005043611A JP2003202361A JP2003202361A JP2005043611A JP 2005043611 A JP2005043611 A JP 2005043611A JP 2003202361 A JP2003202361 A JP 2003202361A JP 2003202361 A JP2003202361 A JP 2003202361A JP 2005043611 A JP2005043611 A JP 2005043611A
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Japan
Prior art keywords
optical sheet
total reflection
unit
light source
optical
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
JP2003202361A
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Japanese (ja)
Inventor
Masahiro Goto
Makoto Honda
正浩 後藤
本田  誠
Original Assignee
Dainippon Printing Co Ltd
大日本印刷株式会社
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Priority to JP2003202361A priority Critical patent/JP2005043611A/en
Publication of JP2005043611A publication Critical patent/JP2005043611A/en
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Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical sheet for uniformly illuminating the whole screen, even when light is introduced by using parallel cathode-ray tubes from the rear face, and to provide a surface light source device and a transmission display device. <P>SOLUTION: The optical sheet has the total reflection faces 122a and 122b causing total reflection of the illumination light from a light source part incident, by having a prescribed or larger incident angle to a sheet face of a base material sheet 121. The optical sheet 12 is provided between an LCD panel 11 and a cathode-ray tube 13 as an optical axis correction part 122, one-dimensionally or two-dimensionally arranging a plurality of unit correction shapes which correct the optical axis at a side opposite to the cathode-ray tube 13 of at least the base material sheet 121 so as to emit toward the LCD panel 11 at an angle smaller than the incident angle. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical sheet used for a backlight such as a liquid crystal display, a surface light source device used as a backlight, and a transmissive display device using them.
[0002]
[Prior art]
In a backlight used for a liquid crystal display or the like, light is introduced from the side by using a cathode ray tube or a cathode ray tube is arranged in parallel on the back side.
However, when light is introduced from the side, there is a problem that the intensity of light cannot be increased more than a certain degree because the number of usable cathode ray tubes is limited.
[0003]
Conventionally, when light is introduced using a parallel cathode ray tube from the back side, the distance between the cathode ray tube and the LCD panel (transmission type display unit) is increased, and a diffusion plate is used between them. Illumination light emitted from the LCD panel can uniformly illuminate the LCD panel.
However, when light is introduced from the back side, in order to suppress unevenness of the light intensity between the gap portion of the cathode ray tube and immediately below, or in order to suppress this, the interval between the cathode ray tube and the LCD panel is largely separated. However, there has been a problem that the amount of light used can be reduced by increasing the thickness of the display, increasing diffusion to suppress unevenness, or limiting the amount of transmission.
[0004]
For these problems, for example, various methods for maintaining uniformity by providing a light-shielding portion as in Patent Document 1 and Patent Document 2 have been proposed.
Further, for example, Patent Document 3 proposes a method using a sheet provided with lenticular lenses on both sides.
[0005]
[Patent Document 1]
Japanese Patent Laid-Open No. 05-119703 [Patent Document 2]
Japanese Patent Laid-Open No. 11-242219 [Patent Document 3]
Japanese Patent Laid-Open No. 06-347613
[Problems to be solved by the invention]
However, the methods described in Patent Documents 1 and 2 have a problem in that the light utilization rate decreases because the light shielding portion is provided.
The method described in Patent Document 3 is a configuration for performing diffusion control in two directions, and has no function of correcting the optical axis. Therefore, if the optical axis varies depending on the position of the LCD due to the positional relationship with the cathode ray tube, there is a problem that brightness spots occur at each position of the screen depending on the position where the screen is observed.
[0007]
An object of the present invention is to provide an optical sheet, a surface light source device, and a transmissive display device that can perform uniform illumination over the entire screen even when light is introduced from the back using a parallel cathode ray tube. It is to be.
[0008]
[Means for Solving the Problems]
The present invention solves the above problems by the following means. In addition, in order to make an understanding easy, although the code | symbol corresponding to embodiment of this invention is attached | subjected and demonstrated, it is not limited to this. That is, the invention of claim 1 is an optical sheet (12, 22) provided between a transmissive display section (11) and a light source section in which a plurality of light sources (13) are arranged in parallel, and is a base sheet. (121, 221) and total reflection surfaces (122a, 122b, 222a, 222b) that totally reflect illumination light from the light source unit incident at a predetermined incident angle or more with respect to the sheet surface of the base sheet And a unit correction shape for correcting the optical axis so as to be emitted toward the transmissive display unit at an angle smaller than the incident angle, at least one-dimensionally on the side of the base sheet facing the light source unit Or it is an optical sheet (12, 22) provided with the optical-axis correction | amendment part (122, 222) formed by arranging two or more two-dimensionally.
[0009]
According to a second aspect of the present invention, in the optical sheet according to the first aspect, the unit correction shapes are arranged in substantially the same direction as the direction in which the light sources (13) are arranged in parallel. Sheet (12, 22).
[0010]
The invention according to claim 3 is the optical sheet according to claim 1 or 2, wherein the unit correction shape is different depending on a distance to the light source (13) when combined with the light source unit. It is an optical sheet (12, 22) characterized by these.
[0011]
According to a fourth aspect of the present invention, in the optical sheet according to any one of the first to third aspects, the unit correction shape is such that the total reflection surfaces (122a, 122b, 222a, 222b) are line symmetric. The optical sheet (12, 22) is characterized in that it is a polygonal shape having a cross-sectional shape arranged so that the interior angles of the polygonal shape are 180 ° or less.
[0012]
According to a fifth aspect of the present invention, in the optical sheet according to any one of the first to fourth aspects, the unit correction shape has two cross-sectional shapes that do not contact the base sheet (121, 221). A pentagonal shape having a first total reflection surface (122a, 222a) comprising a gentle slope and a second total reflection surface (122b, 222b) comprising two steep slopes in contact with the base sheet, or the first In addition to the total reflection surface and the second total reflection surface, a flat surface substantially parallel to the base sheet is provided between the two gentle slopes forming the pentagonal first total reflection surface. It is an optical sheet (12, 22) characterized by having a hexagonal shape.
[0013]
According to a sixth aspect of the present invention, in the optical sheet according to the fifth aspect, when the angle formed by the two gentle slopes is the apex angle θ °, and the angle formed by the steep slope and the base sheet is the base angle φ ° The optical sheet is characterized by having a relationship of θ / 2> (90 ° −φ).
[0014]
The invention according to claim 7 is the optical sheet according to claim 6, wherein the apex angle θ ° is 10 ° or more and 90 ° or less.
[0015]
The invention according to claim 8 is the optical sheet according to claim 5, wherein the base angle φ ° is not less than 60 ° and not more than 85 °.
[0016]
According to a ninth aspect of the present invention, in the optical sheet according to the fourth aspect, the cross-sectional shape of the total reflection surface is a curve, and the total reflection surface intersects on the axis of symmetry in the cross section. The optical sheet (see FIG. 9) is characterized in that an angle formed by tangents of the curve at the apex portion is 30 ° or more and 45 ° or less.
[0017]
The invention according to claim 10 is the optical sheet according to claim 4, wherein the cross-sectional shape of the total reflection surface is a curve, and the cross section of the cross section of the total reflection surface and the base sheet is the cross section. The optical sheet (see FIG. 9) is characterized in that an angle formed between a tangent line of the curve and the surface of the base sheet is 60 ° to 85 °.
[0018]
The invention according to claim 11 is the optical sheet according to any one of claims 1 to 10, wherein the side facing the light source unit has a surface on which the base sheet becomes a surface, or The optical sheet (12) is characterized in that a surface (122c) parallel to the base sheet is formed.
[0019]
According to a twelfth aspect of the present invention, in the optical sheet according to any one of the first to eleventh aspects, a lenticular lens portion (123) is formed on a side facing the transmissive display portion. This is an optical sheet characterized by the above.
[0020]
A thirteenth aspect of the invention is an optical sheet according to any one of the first to twelfth aspects, wherein at least a part of the optical sheet contains fine particles for light diffusion. is there.
[0021]
The invention of claim 14 is a surface light source device for illuminating the transmissive display unit (11) from the back, and a light source unit in which a plurality of light sources (13) are arranged in parallel, and claims 1 to 13 A surface light source device comprising the optical sheet (12, 22) according to any one of the above items.
[0022]
A fifteenth aspect of the invention is a transmissive display device including the transmissive display unit (11) and the surface light source device (12, 13, 22) according to the fourteenth aspect.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings.
(First embodiment)
FIG. 1 is a diagram showing a transmissive display device according to a first embodiment of the present invention. In addition, each figure shown below including FIG. 1 is the figure shown typically, and the magnitude | size and shape of each part are exaggerated suitably for easy understanding.
The transmissive display device 10 according to the present embodiment includes an LCD panel 11, an optical sheet 12, a cathode ray tube 13, and the like, and image information formed on the LCD panel 11 is backed by a surface light source device including the optical sheet 12 and the cathode ray tube 13. It is a transmissive liquid crystal display device which illuminates from.
[0024]
The LCD panel 11 is a so-called transmissive liquid crystal display element, and can display a 30-inch size and 800 × 600 dots.
The cathode ray tube 13 is a line light source that forms a light source unit of a backlight. In this embodiment, six cathode ray tubes 13 are arranged in parallel at regular intervals of about 75 mm.
A reflection plate (not shown) is provided on the back surface of the cathode ray tube 13, and the design makes it possible to make the incident light illuminance to each part of the screen uniform.
The distance between the cathode ray tube 13 and the optical sheet 12 is 25 mm.
[0025]
The optical sheet 12 is provided between the cathode ray tube 13 and the LCD panel 11, corrects the optical axis so that illumination light emitted from the cathode ray tube 13 is emitted substantially perpendicularly to the LCD panel 11, and It is a sheet provided so as to have a uniform illuminance distribution regardless of the position.
The transmissive display device according to this embodiment has the above-described configuration and a thickness of 70 mm.
[0026]
FIG. 2 is a diagram showing the optical sheet 12. FIG. 2A shows the entire optical sheet 12, and FIG. 2B is a cross-sectional view taken along the line AA 'shown in FIG.
The optical sheet 12 in this embodiment includes a base sheet 121, an optical axis correction unit 122, and a lenticular lens unit 123.
The base material sheet 121 is a transparent base material formed in a sheet shape with a thickness of about 1 to 3 mm. The base sheet 121 is made of, for example, acrylic resin, polystyrene, polycarbonate, epoxy resin, or the like.
[0027]
The optical axis correction unit 122 is provided on the incident side (cathode ray tube 13 side) of the base sheet 121, and has an incident angle greater than a predetermined angle with respect to the sheet surface of the base sheet 121 (incident light forms a perpendicular to the sheet surface. The unit correction shape has a total reflection surface that totally reflects the illumination light from the cathode ray tube 13 incident at an angle (hereinafter, the same applies to the emission angle). This unit correction shape is a columnar portion extending in a direction parallel to the cathode ray tube 13, and the cross-sectional shape in the direction orthogonal to the longitudinal direction is a first composed of two gentle slopes not in contact with the base sheet 121. It has a pentagonal shape having a total reflection surface 122a and a second total reflection surface 122b composed of two steep slopes in contact with the base sheet 121.
[0028]
FIG. 3 is an enlarged view of the cross-sectional shape of the optical axis correction unit 122.
The optical axis correction unit 122 has an apex angle θ of the intersection (vertex) of the two first total reflection surfaces 122a = 35 °, and a base angle φ that is an angle formed between the base sheet 121 and the second total reflection surface 122b. = 82 °, and the height of the isosceles triangle formed by the two first total reflection surfaces 122a is 0.02 mm.
Here, the apex angle θ ° is preferably 10 ° or more and 90 ° or less, and the base angle φ ° is preferably 60 ° or more and 85 ° or less, and further has a relationship of θ / 2> (90 ° −φ). In this embodiment, this relationship is satisfied. By satisfying this condition, all the internal angles of the unit correction shape become 180 ° or less, and the effect of optical axis correction described later can be sufficiently exhibited.
[0029]
In the optical axis correction unit 122, the unit correction shape having the above pentagonal cross-sectional shape is arranged in parallel at a pitch of 0.03 mm in a direction substantially the same as the direction in which the cathode ray tubes 13 are arranged in parallel. It has a function of correcting the optical axis so that the light is emitted toward the transmissive display unit at a smaller angle.
Further, a flat portion 122 c is provided between the adjacent optical axis correction units 122. The flat portion 122c is provided with a width of about 3 μm, and the light passing through this portion is emitted as it is with little optical axis correction.
[0030]
The lenticular lens portion 123 has a unit lens whose cross section is a part of an ellipse, and is formed of, for example, acrylic resin, polystyrene, polycarbonate, epoxy resin, or the like. The cross-sectional shape of the unit lens of the lenticular lens 123 is not limited to an ellipse, but may be other shapes such as a parabola or a part of a hyperbola.
In the present embodiment, the optical axis correction unit 122 and the lenticular lens unit 123 are arranged such that unit lenses are arranged substantially in parallel at a pitch P = 0.1 mm. The direction in which the lenticular lens portions 123 are arranged is arranged in substantially the same direction as the unit correction shape of the optical axis correction unit 122 and the direction in which the cathode ray tubes 13 are arranged in parallel.
[0031]
Here, the lens pitch P of the optical axis correction unit 122 and the lenticular lens unit 123 is in any one of the following conditions in relation to the video pitch D of the matrix video in order to prevent moire from the matrix video of the LCD panel 11 or the like. It is recommended that the above be satisfied. That is, condition 1: (D / P) = 2 / (2n + 1) or (D / P) = (2n + 1) / 2 (where n is a natural number) or (where n is a non-negative integer). Condition 2: (D / P)> 3.5 or (P / D)> 3.5, more preferably (D / P)> 4.5 or (P / D)> 4.5 The lens pitch P may be determined so as to satisfy any of the following.
[0032]
(Manufacturing method of the optical sheet 12)
Here, the manufacturing method of the optical sheet 12 in this embodiment is demonstrated.
In the present embodiment, the optical sheet 12 is manufactured by a so-called 2P method using an ultraviolet curable resin for forming the optical axis correction unit 122 and the lenticular lens unit 123.
First, a mold corresponding to the shapes of the optical axis correction unit 122 and the lenticular lens unit 123 is filled with an ultraviolet curable resin by a roll coating method, a gravure method, a dispenser method, a die coating method, or the like. After the mold is filled with the ultraviolet curable resin, a base sheet is laminated on the ultraviolet curable resin filled in the mold and is pressed by a pressure roller so that the ultraviolet curable resin and the base sheet are brought into close contact with each other. When the ultraviolet curable resin and the base sheet are brought into close contact with each other, the ultraviolet curable resin is irradiated with ultraviolet rays from the base sheet to cure the ultraviolet curable resin. Finally, the cured ultraviolet curable resin is released from the mold. The optical sheet 12 is completed by performing this operation on both sides.
The optical sheet 12 manufactured in this way is cut into a predetermined size as necessary and used as an optical sheet 12 for a backlight.
[0033]
The production of the optical sheet 12 is not limited to the 2P method using the ultraviolet curable resin described above, and corresponds to the optical sheet 12 using a resin material such as acrylic resin, polystyrene, polycarbonate, epoxy resin, or the like. A method of filling a mold with a resin material in a monomer state, polymerizing and curing, and then releasing the mold (casting method), or a method of releasing a mold after filling a similar resin mold with a heated resin material and pressurizing ( It can be manufactured by a hot press method).
[0034]
FIG. 4 is a diagram for explaining how the optical sheet 12 works in the transmissive display device of the present embodiment. FIG. 4 shows a cross section similar to that of FIG.
In the cross section shown in FIG. 4, the illumination light emitted from the cathode ray tube 13 spreads in all directions around the cathode ray tube 13 and enters the optical sheet 12 at various angles.
Illumination light that is incident from a direction substantially orthogonal to the sheet surface of the optical sheet 12 (incident at an incident angle of approximately zero) is reflected by the first total reflection surface 122a and the second total reflection surface 122b and is emitted. Or is incident on the flat portion 122c of the optical axis correction unit 122 and hardly undergoes correction of the optical axis, and then refracted and exits when exiting the lenticular lens unit 123. All of these illumination lights are emitted from the optical sheet 12 so as to enter the LCD panel 11 substantially perpendicularly.
[0035]
In addition, the illumination light that is incident on the optical sheet 12 at a relatively large incident angle is incident on the optical axis correction unit 122, then is reflected by the first total reflection surface 122a and the second total reflection surface 122b, and thereafter The light is refracted and emitted when exiting from the lenticular lens portion 123.
Therefore, even if the illumination light is incident on the optical sheet 12 from the cathode ray tube 13 at a relatively large incident angle, the incident light is incident on the LCD panel 11 with a small incident angle (nearly perpendicular). Become.
[0036]
Here, the effect of setting the cross-sectional shape of the unit correction shape of the optical axis correction unit 122 to a substantially pentagon will be described. If the cross-sectional shape of the unit correction shape is a simple shape, an isosceles triangle can be considered.
FIG. 5 is a diagram comparing the case where the unit correction shape of the optical axis correction unit 122 is an isosceles triangle and a pentagon as a cross-sectional shape.
FIG. 5A is an example in which the cross-sectional shape of the unit correction shape of the optical axis correction unit 122 is an isosceles triangle (optical axis correction unit 122 ′), and FIG. 5B is the cross-sectional shape of the unit correction shape. Is an example of a pentagon (optical axis correction unit 122 of the present embodiment).
[0037]
As is clear by comparing FIG. 5A and FIG. 5B, the optical sheet 12 of this embodiment is particularly advantageous when the incident angle is steep compared to the case of an isosceles triangle. It is. In the case of an isosceles triangle, when the angle is 45 ° or more (when the base angle is about 10 °), the light that is first incident on the lens is refracted without being totally reflected, so that it does not satisfy the total reflection condition. The correction effect may be significantly reduced. On the other hand, if the shape of the top of the pentagonal cross section is a gentle slope, total reflection is easy for light from an oblique direction. Further, since the light from obliquely selectively hits the vicinity of the top of the lens, a higher effect can be expected.
By such an effect, it is possible to correct up to an emission angle of about ± 30 ° up to an incident angle of about 70 °.
[0038]
In this way, by making the cross-sectional shape of the unit correction shape a pentagon, the optical axis correction effect is enhanced, and even if the illumination light is incident on the optical sheet 12 at a large incident angle, the LCD panel 11 is affected. Can be emitted at an angle close to a right angle.
Also, by providing a lenticular lens on the exit side, the optical axis is corrected and moderately diffused, and the light that could not be corrected sufficiently is returned to the light source side by the total reflection effect of the lenticular lens, thereby illuminating light. Can be used effectively.
As described above, in the transmissive display device according to the present embodiment, the optical axis of the illumination light is corrected by the optical sheet 12. Therefore, the luminance difference of the display image depending on the location is within 20%, and the luminance unevenness is practically used. Cannot be confirmed, and uniform brightness can be obtained.
[0039]
(Comparative example)
In order to confirm the effect of the optical sheet 12 in the present embodiment, the following transmissive display device was created.
FIG. 6 is a diagram showing a transmissive display device created as a comparative example. FIG. 6 shows the same as FIG.
In the comparative example shown in FIG. 6, the LCD panel 11 capable of displaying the same 30-inch size and 800 × 600 dots as in the above-described embodiment is used. Further, the cathode ray tube 13 is the same as that in the above-described embodiment, and six cathode ray tubes 13 are arranged on the back surface of the LCD panel 11 at approximately 75 mm intervals and approximately in parallel at equal intervals. In the comparative example shown in FIG. 6, a diffusion plate 14 is arranged between the LCD panel 11 and the cathode ray tube 13. The distance between the diffusion plate 14 and the cathode ray tube 13 is 70 mm. This interval is such that the difference in luminance of the illumination light is minimized depending on the position on the LCD panel 11.
The transmission type display device in this comparative example has the above-described configuration, and its thickness is 120 mm.
[0040]
When the transmissive display device of the completed comparative example was operated and observed, the luminance difference of the display image depending on the location was 50% at maximum in this comparative example.
Further, in this comparative example, the luminance unevenness when observed from the front can be corrected, but when the viewpoint is moved, the luminance unevenness corresponding to the position of the cathode ray tube has been confirmed.
Further, the transmittance decrease due to the diffusion plate 14 is about 20%, and furthermore, the transmittance decrease due to the diffusion of the incident light to the LCD panel 11 occurs 30% compared to the above-described embodiment. .
[0041]
As described above, in the transmissive display device of the comparative example, although the thickness of the device is increased, the brightness difference of the display image is large, uneven, and the transmittance is low, so that the brightness is low. Compared with the transmissive display device of the embodiment of the present invention, it was clearly inferior in all aspects.
[0042]
According to the present embodiment, since the optical sheet 12 having the base sheet 121, the optical axis correction unit 122, and the lenticular lens unit 123 is inserted into the gap between the cathode ray tube 13 and the LCD panel 11, the cathode ray tube 13 and the LCD panel are inserted. 11 is corrected by the positional relationship with the cathode ray tube 13 in the incident direction of the light to the light source 11, and can enter the LCD panel 11 substantially vertically. Therefore, it is possible to ensure a uniform direction and intensity of incident light at any position on the LCD panel 11, suppress unevenness in the intensity of the image, and suppress a loss of light amount by obtaining an appropriate diffusion characteristic. The transmittance in the panel 11 can also be increased.
[0043]
In the transmissive display device configured as described above, the incident angle of the illumination light from the cathode ray tube 13 to the LCD panel 11 is substantially zero (substantially perpendicularly incident) by the action of the optical sheet 12 as described above. Therefore, the observer can observe the image on the LCD panel 11 with high brightness and without unevenness.
[0044]
Moreover, in this embodiment, since the optical sheet 12 has the optical axis correction part 122 and the lenticular lens part 123 formed on both surfaces of the base sheet 121 with an ultraviolet curable resin, the optical sheet 12 can be easily manufactured. it can.
[0045]
(Second Embodiment)
FIG. 7 is a diagram showing a transmissive display device according to a second embodiment of the present invention.
The second embodiment is the same as the first embodiment except that the optical sheet 12 is changed to the optical sheet 22 in the first embodiment. Therefore, the second embodiment has the same functions as those of the first embodiment. The same reference numerals are given to the parts fulfilled, and the repeated description will be omitted as appropriate.
[0046]
FIG. 8 is a diagram showing the optical sheet 22. Fig.8 (a) shows the whole optical sheet 12, FIG.8 (b) is the figure which expanded a part of Fig.8 (a). In FIG. 8, unlike FIG. 2, the incident side is shown upward.
In the optical sheet 22 in the second embodiment, the optical axis correction unit 122 of the optical sheet 12 in the first embodiment is formed in a columnar shape, whereas the optical axis correction unit 122 in the second embodiment is formed in a cone shape. The point that I did is very different. Specifically, the cross-sectional shape (illustrated by hatching in FIG. 8B) passing through the apex of the optical axis correction unit 222 and orthogonal to the base material sheet 221 is two gentle slopes that do not contact the base material sheet 221. The pentagonal shape has a first total reflection surface 222a made of the second total reflection surface 222b made of two steep slopes in contact with the base material sheet 221, and a rotating body (weight-like shape) obtained by rotating the pentagonal shape. ) Is the unit correction shape.
[0047]
The dimensions of the pentagonal shape in the present embodiment are the same as the cross-sectional shape of the optical axis correction unit 122 in the first embodiment, and the preferred ranges of the apex angle θ ° and the base angle φ ° are also the same.
Furthermore, in the optical axis correction unit 222, the above-mentioned unit correction shape having a pentagonal cross section is arranged in parallel at a pitch of 0.03 mm in the same direction as the direction in which the cathode ray tubes 13 are arranged in parallel. And has a function of correcting the optical axis so that the light is emitted toward the transmissive display unit at an angle smaller than the incident angle.
[0048]
The lenticular lens portion formed in the first embodiment is not formed on the emission side of the optical sheet 22 in the present embodiment. If necessary, a lenticular lens portion and a lens array (so-called fly-eye lens) may be added to this surface.
[0049]
The optical sheet 22 in the present embodiment can be manufactured by the 2P method using an ultraviolet curable resin, as in the first embodiment. Then, according to the 2P method using this ultraviolet curable resin, the cone-shaped optical axis correction unit 222 having a sharp tip can be molded with good reproducibility.
As in the first embodiment, the optical sheet 22 can be manufactured by a casting method, a hot press method, or the like.
[0050]
In the optical sheet 12 in the first embodiment, the optical path of the illumination light is mainly adjusted in a plane perpendicular to the longitudinal direction of the optical axis correction unit 122, whereas in the optical sheet 22, the unit correction shape is rotated. Considering a certain plane (cross section) including the axis, the optical path of the illumination light is adjusted in the same manner as in the first embodiment, and the plane exists in all directions around the rotation axis.
Therefore, the optical sheet 22 according to the present embodiment causes the illumination light incident on an arbitrary point to be incident on the plane including the point and the rotation axis of the unit correction shape of the optical axis correction unit 222 by the same action as in the first embodiment. Since it is emitted, illumination light incident at any incident angle can be emitted as illumination light in a direction substantially orthogonal to the LCD panel 11.
[0051]
As described above, in this embodiment, the optical axis correction unit 222 has a configuration in which spindle-shaped rotating bodies are assembled. Therefore, the direction in which the optical axis is corrected is not limited to one cross-sectional direction, and the light is corrected in all directions. The axis can be corrected. Therefore, in the present embodiment, an example in which the cathode ray tubes 13 that are line light sources are arranged in parallel is shown. However, for example, even when point light sources are arranged, it is uniform at any position on the LCD panel 11. The direction and intensity of the incident light can be ensured, the intensity unevenness of the image can be suppressed, the loss of light amount can be suppressed by obtaining appropriate diffusion characteristics, and the transmittance of the LCD panel 11 can be increased.
[0052]
(Deformation)
The present invention is not limited to the embodiment described above, and various modifications and changes are possible, and these are also within the equivalent scope of the present invention.
(1) In each embodiment, in the cross section of the unit correction shape, the example in which the portion forming the total reflection surface is a straight cross section is shown. However, the present invention is not limited to this. For example, the unit correction shape shown in FIG. Like 322, the total reflection surface may have a cross-sectional shape defined by a curve.
In this case, the angle formed by the tangents of the curves at the apex portion formed by the total reflection surfaces intersecting on the symmetry axis may be 30 ° or more and 45 ° or less, and the total reflection surface and the substrate sheet The angle formed between the tangent line of the curved line at the intersection and the surface of the base sheet is preferably 60 ° to 85 °.
By doing so, the optical axis correction effect can be changed smoothly.
[0053]
(2) In the first embodiment, the example in which the unit correction shapes are arranged slightly apart and the flat portion 122c is provided is shown (FIG. 10A). However, the present invention is not limited to this. For example, FIG. As shown in b), a flat portion 122c ′ may be provided at the tip of the pentagon (near the apex).
[0054]
(3) In each embodiment, although the cross-sectional shape of the optical axis correction | amendment parts 122 and 222 showed the example equal in all the positions, it is not restricted to this, For example, according to the positional relationship with the cathode ray tube 13 (cathode ray | wire) The unevenness in illuminance may be adjusted by changing the shape of the unit lens (depending on the distance to the tube 13).
[0055]
(4) In each embodiment, an appropriate diffusion effect may be imparted to a part of the optical sheet by including fine particles for light diffusion.
[0056]
【The invention's effect】
As described above in detail, according to the present invention, the following effects can be obtained.
(1) A transmissive display unit having a total reflection surface that totally reflects illumination light from a light source unit that is incident on the sheet surface of the substrate sheet with a predetermined incident angle or more and having an angle smaller than the incident angle Since the optical axis correction unit is formed by arranging a plurality of unit correction shapes for correcting the optical axis so as to be emitted toward the light source unit at least on the side facing the light source unit of the base sheet, at any position of the transmissive display unit In addition, it is possible to ensure a uniform direction and intensity of incident light, and to suppress unevenness in the intensity of the image.
[0057]
(2) Since the unit correction shapes are arranged in substantially the same direction as the direction in which the light sources are arranged in parallel, the unit correction shape should be the most effective arrangement for correcting the optical axis of the illumination light emitted from the light sources. It is possible to increase the optical axis correction effect.
[0058]
(3) Since the unit correction shape varies depending on the distance to the light source when combined with the light source unit, the illuminance unevenness can be adjusted regardless of the distance from the light source.
[0059]
(4) The unit correction shape is a polygonal shape having a cross-sectional shape arranged so that the total reflection surface is line-symmetric, and the interior angle of each polygonal shape is 180 ° or less. A unit correction shape effective for obtaining an axis correction effect can be obtained.
[0060]
(5) The cross-sectional shape of the unit correction shape is a pentagonal shape having a first total reflection surface consisting of two gentle slopes and a second total reflection surface consisting of two steep slopes, or the first total reflection surface and Since the hexagonal shape has a flat surface in addition to the second total reflection surface, the optical axis can be effectively corrected even with a simple shape that is easy to manufacture.
[0061]
(6) Since the angle between the two gentle slopes is the apex angle θ ° and the angle between the steep slope and the base sheet is the base angle φ °, there is a relationship of θ / 2> (90 ° −φ). The unit correction shape effective for obtaining the optical axis correction effect can be obtained.
[0062]
(7) Since the apex angle θ ° is not less than 10 ° and not more than 90 °, the effect of correcting the optical axis can be sufficiently obtained, and the manufacturing can be easily performed.
[0063]
(8) Since the base angle φ ° is not less than 60 ° and not more than 85 °, a sufficient optical axis correction effect can be obtained.
[0064]
(9) The cross-sectional shape of the total reflection surface is a curve, and the angle formed by the tangents of the curves at the apex portion formed by the cross-section of the total reflection surfaces on the axis of symmetry is 30 ° or more and 45 °. Since it is below, the correction effect of an optical axis can fully be acquired and manufacture can be performed easily.
[0065]
(10) The cross-sectional shape of the total reflection surface is a curve, and the angle formed by the tangent of the curve at the intersection of the total reflection surface and the base sheet in the cross section is 60 ° or more and 85 Since it is less than or equal to 0 °, a sufficient optical axis correction effect can be obtained.
[0066]
(11) On the side facing the light source part, a surface that is the surface of the base sheet or a surface that is parallel to the base sheet is formed, so that the surface is substantially orthogonal to the optical sheet. The incident illumination light can be emitted without correcting the optical axis.
[0067]
(12) Since the lenticular lens portion is formed on the side facing the transmissive display portion, the effect of optical axis correction can be further obtained, and uniform illumination light can be obtained by obtaining appropriate diffusion characteristics. Sex can be made higher.
[0068]
(13) Since at least a portion contains the light diffusing fine particles, the uniformity of the illumination light can be further increased by obtaining appropriate diffusion characteristics.
[Brief description of the drawings]
FIG. 1 is a diagram showing a transmissive display device according to a first embodiment of the present invention.
FIG. 2 is a view showing an optical sheet 12;
3 is an enlarged view of a cross-sectional shape of an optical axis correction unit 122. FIG.
FIG. 4 is a diagram for explaining how the optical sheet 12 acts in the transmissive display device of the present embodiment.
FIG. 5 is a diagram showing a comparison between a case where an isosceles triangle is used as a cross-sectional shape of a unit correction shape of the optical axis correction unit 122 and a case where a pentagon is used.
FIG. 6 is a diagram showing a transmissive display device created as a comparative example.
FIG. 7 is a diagram showing a transmissive display device according to a second embodiment of the invention.
8 is a view showing an optical sheet 22. FIG.
FIG. 9 is a diagram showing a modification in which the total reflection surface is a curve.
FIG. 10 is a diagram showing a modified form of a flat portion.
[Explanation of symbols]
10, 20 Transmission type display device 11 LCD panel 12, 22 Optical sheet 13 Cathode ray tube 14 Diffusion plate 121 Base sheet 122, 222, 322, 122 'Optical axis correction unit 122a, 222a First total reflection surface 122b, 222b 2 total reflection surfaces 122c, 122c ′ flat portion 123 lenticular lens portion

Claims (15)

  1. An optical sheet provided between a transmissive display unit and a light source unit in which a plurality of light sources are arranged in parallel,
    A base sheet;
    The transmissive display has a total reflection surface that totally reflects the illumination light from the light source unit that is incident on the sheet surface of the base sheet with an incident angle greater than or equal to a predetermined angle, and is less than the incident angle. An optical axis correction unit formed by aligning a plurality of one-dimensional or two-dimensional unit correction shapes for correcting the optical axis so as to be emitted toward the unit at least on the side of the base sheet facing the light source unit;
    An optical sheet comprising:
  2. The optical sheet according to claim 1,
    The unit correction shapes are arranged in substantially the same direction as the direction in which the light sources are arranged in parallel;
    An optical sheet characterized by
  3. In the optical sheet according to claim 1 or 2,
    The unit correction shape is different depending on the distance to the light source when combined with the light source unit,
    An optical sheet characterized by
  4. In the optical sheet according to any one of claims 1 to 3,
    The unit correction shape is a polygonal shape having a cross-sectional shape arranged so that the total reflection surface is line symmetric,
    The interior angles of the polygonal shape are all 180 ° or less,
    An optical sheet characterized by
  5. In the optical sheet according to any one of claims 1 to 4,
    The cross-sectional shape of the unit correction shape is a pentagon having a first total reflection surface consisting of two gentle slopes not in contact with the base sheet and a second total reflection surface consisting of two steep slopes in contact with the base sheet. Shape or the base sheet between two gentle slopes forming the pentagonal first total reflection surface in addition to the first total reflection surface and the second total reflection surface A hexagonal shape with a substantially parallel flat surface,
    An optical sheet characterized by
  6. The optical sheet according to claim 5,
    When the angle between the two gentle slopes is the apex angle θ °, and the angle between the steep slope and the base sheet is the base angle φ °, there is a relationship of θ / 2> (90 ° −φ). ,
    An optical sheet characterized by
  7. The optical sheet according to claim 6,
    The apex angle θ ° is 10 ° or more and 90 ° or less,
    An optical sheet characterized by
  8. The optical sheet according to claim 5,
    The base angle φ ° is 60 ° or more and 85 ° or less,
    An optical sheet characterized by
  9. The optical sheet according to claim 4,
    The cross-sectional shape of the total reflection surface is a curve,
    In the cross section, the angle formed by the tangents of the curve at the apex portion formed by the total reflection surfaces intersecting on the symmetry axis is 30 ° or more and 45 ° or less,
    An optical sheet characterized by
  10. The optical sheet according to claim 4,
    The cross-sectional shape of the total reflection surface is a curve,
    In the cross section, an angle formed between a tangent line of the curve at the intersection of the total reflection surface and the base sheet and the surface of the base sheet is 60 ° to 85 °,
    An optical sheet characterized by
  11. In the optical sheet according to any one of claims 1 to 10,
    On the side facing the light source unit, a surface that is the surface of the base sheet, or a surface that is parallel to the base sheet is formed,
    An optical sheet characterized by
  12. In the optical sheet according to any one of claims 1 to 11,
    A lenticular lens portion is formed on the side facing the transmissive display portion;
    An optical sheet characterized by
  13. In the optical sheet according to any one of claims 1 to 12,
    Contain at least a part of light diffusion particles,
    An optical sheet characterized by
  14. A surface light source device that illuminates a transmissive display unit from the back,
    A light source unit in which a plurality of light sources are arranged in parallel;
    The optical sheet according to any one of claims 1 to 13,
    A surface light source device comprising:
  15. A transmissive display;
    A surface light source device according to claim 14,
    A transmissive display device.
JP2003202361A 2003-07-28 2003-07-28 Optical sheet, surface light source device, and transmission-type display device Pending JP2005043611A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2003202361A JP2005043611A (en) 2003-07-28 2003-07-28 Optical sheet, surface light source device, and transmission-type display device

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2003202361A JP2005043611A (en) 2003-07-28 2003-07-28 Optical sheet, surface light source device, and transmission-type display device

Publications (1)

Publication Number Publication Date
JP2005043611A true JP2005043611A (en) 2005-02-17

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Cited By (14)

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JP2005326819A (en) * 2004-04-12 2005-11-24 Kuraray Co Ltd Light diffusion plate
JP2006302622A (en) * 2005-04-19 2006-11-02 Cheil Ind Co Ltd Surface light source device
JP2007095386A (en) * 2005-09-27 2007-04-12 Nippon Zeon Co Ltd Direct backlight device
JP2007114587A (en) * 2005-10-21 2007-05-10 Takiron Co Ltd Light diffusion sheet
WO2007066729A1 (en) * 2005-12-09 2007-06-14 Sony Corporation Surface light emission device and liquid crystal display
JP2008122656A (en) * 2006-11-13 2008-05-29 Sumitomo Chemical Co Ltd Transmission type image display device
WO2009044701A1 (en) * 2007-10-01 2009-04-09 Dai Nippon Printing Co., Ltd. Optical sheet, molding, production method of molding and production method of optical sheet
US7719635B2 (en) * 2006-06-21 2010-05-18 Fujifilm Corporation Optical sheet and manufacturing method thereof, backlight, liquid crystal display
JP2010250987A (en) * 2009-04-13 2010-11-04 Toppan Printing Co Ltd Light uniforming element, optical sheet, backlight unit and display device
JP2011503643A (en) * 2007-11-06 2011-01-27 エルエムエス・カンパニー・リミテッドLMS Co.,Ltd. Optical film and illumination device including the same
WO2012005135A1 (en) * 2010-07-07 2012-01-12 シャープ株式会社 Light diffusion sheet and display device provided with the light diffusion sheet
JP2012185508A (en) * 2012-04-27 2012-09-27 Sumitomo Chemical Co Ltd Transmission type image display device
KR101291938B1 (en) * 2005-12-30 2013-07-31 엘지디스플레이 주식회사 Backlight assembly and liquid crystal display device having the same
JP2013242516A (en) * 2012-05-21 2013-12-05 Samsung Display Co Ltd Display panel

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005326819A (en) * 2004-04-12 2005-11-24 Kuraray Co Ltd Light diffusion plate
JP4638752B2 (en) * 2004-04-12 2011-02-23 株式会社クラレ Light diffusion plate
JP2006302622A (en) * 2005-04-19 2006-11-02 Cheil Ind Co Ltd Surface light source device
JP2007095386A (en) * 2005-09-27 2007-04-12 Nippon Zeon Co Ltd Direct backlight device
JP2007114587A (en) * 2005-10-21 2007-05-10 Takiron Co Ltd Light diffusion sheet
JP4992721B2 (en) * 2005-12-09 2012-08-08 ソニー株式会社 Surface light emitting device and liquid crystal display device
WO2007066729A1 (en) * 2005-12-09 2007-06-14 Sony Corporation Surface light emission device and liquid crystal display
KR101291938B1 (en) * 2005-12-30 2013-07-31 엘지디스플레이 주식회사 Backlight assembly and liquid crystal display device having the same
US7719635B2 (en) * 2006-06-21 2010-05-18 Fujifilm Corporation Optical sheet and manufacturing method thereof, backlight, liquid crystal display
JP2008122656A (en) * 2006-11-13 2008-05-29 Sumitomo Chemical Co Ltd Transmission type image display device
WO2009044701A1 (en) * 2007-10-01 2009-04-09 Dai Nippon Printing Co., Ltd. Optical sheet, molding, production method of molding and production method of optical sheet
JP2011503643A (en) * 2007-11-06 2011-01-27 エルエムエス・カンパニー・リミテッドLMS Co.,Ltd. Optical film and illumination device including the same
JP2010250987A (en) * 2009-04-13 2010-11-04 Toppan Printing Co Ltd Light uniforming element, optical sheet, backlight unit and display device
WO2012005135A1 (en) * 2010-07-07 2012-01-12 シャープ株式会社 Light diffusion sheet and display device provided with the light diffusion sheet
JP2012185508A (en) * 2012-04-27 2012-09-27 Sumitomo Chemical Co Ltd Transmission type image display device
JP2013242516A (en) * 2012-05-21 2013-12-05 Samsung Display Co Ltd Display panel

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