TW201326929A - Light guide plate, surface light source apparatus, transmission type image display apparatus, method of designing light distribution pattern for light guide plate, and method of manufacturing light guide plate - Google Patents

Abstract

The present invention provides a light guide plate that can reduce brightness unevenness in the vicinity of light-incidence part, a surface light source apparatus, a transmission type image display apparatus, a method of designing light distribution pattern for light guide plate, and a method of manufacturing light guide plate. The light guide plate comprises a light guide plate substrate 11 for light propagation, and a plurality of optical reflection points 12 formed on at least one surface of the light guide plate substrate. Surface that is formed with light reflection points, i.e. the point-forming surface S2, is imaginarily divided into a plurality of imaginary regions A at equal intervals, and a plurality of imaginary lattices g is regularly arranged in two-dimension. Light reflection points are formed at specific imaginary lattices in the plural imaginary lattices. The plural light reflection points are formed on the point-forming surface in such a light distribution pattern that the configuration of light reflection points in one of the plural imaginary regions is translational symmetric to the configuration of light reflection points in at least one of the remaining imaginary regions.

Description

Light guide plate, surface light source device, transmissive image display device, design method of light distribution pattern for light guide plate, and method for manufacturing light guide plate

The present invention relates to a light guide plate, a surface light source device, a transmissive image display device, a design method of a light distribution pattern for a light guide plate, and a method of manufacturing a light guide plate.

A transmissive image display device such as a liquid crystal display device generally has a surface light source device that supplies planar light by a light guide plate as a backlight. As for the surface light source device, there is a direct type in which a light source is disposed on the back side of the light guide plate, and an edge illumination method in which a light source is disposed along a side surface of the light guide plate. The edge illumination method is advantageous from the viewpoint of thinning of the image display device.

In the edge light source device, the light incident from the side surface of the light guide plate is reflected and diffused by the light distribution pattern (for example, the light distribution pattern including the light reflection point) provided on the back side of the light guide plate. (scattering), the light of the angular component above the critical angle is emitted from the exit surface of the light guide plate to supply the planar light. In order to make the brightness of the light-emitting surface uniform, the light guide plate described in Japanese Laid-Open Patent Publication No. 2004-240294, and the patent document 2: JP-A-2008-27609, The density of the light distribution pattern is self-drained to a dense gradation.

Further, Patent Document 1 also discloses a method of forming such a dot-like light distribution pattern by droplet discharge (for example, inkjet printing). For example, in the inkjet printing method, in order to shorten the printing tact, a plurality of inkjet heads are arranged to print ink.

Here, when the image display apparatus is further thinned, the number of times of reflection of light in the light guide plate is increased. Therefore, it is necessary to perform printing by setting the vicinity of the light source to a lower coverage ratio, for example, 0.1% or more and 30% or less.

Further, in order to reduce the cost, if the LEDs are arranged in the short-side direction and/or the light is incident only from one direction, the optical path becomes long. Therefore, similarly to the reduction in thickness, it is necessary to set the vicinity of the light source to be lower. The coverage rate is printed.

However, when the light reflection point is printed at a lower coverage ratio near the light entrance portion of the light from the light source, since the light reflection point is small, the difference between the printed area and the non-printed area is large. In the vicinity of the light part, uneven brightness such as smoke is generated.

In view of the above, an object of the present invention is to provide a light guide plate, a surface light source device, a transmissive image display device, and a light distribution pattern for a light guide plate which can be reduced in brightness unevenness in the vicinity of a light incident portion where light is incident. Method and method of manufacturing a light guide plate.

The light guide plate of the present invention comprises a light guide plate substrate that propagates light, and has a plurality of light reflection points formed on at least one side of the light guide plate substrate. In the light guide plate, each of a plurality of imaginary regions obtained by dividing a plurality of light reflection points, that is, a dot formation surface, at a predetermined interval and imaginarily dividing into a plurality of imaginary regions is regularly arranged two-dimensionally as a print target. The plurality of imaginary lattices are formed by imaginary lattices specified in a plurality of imaginary lattices arranged in two dimensions, and light reflection points are formed. The plurality of light reflecting points are formed on the dot forming surface by a light distribution pattern, that is, the light reflecting pattern is arranged from a plurality of imaginary regions in a selected one of the plurality of imaginary regions The configuration of the light reflection point in at least one of the remaining imaginary regions is translational symmetry (translational symmetry).

In this case, the light distribution pattern including the plurality of light reflection points has a regularity of arrangement of light reflection points in at least one of the plurality of imaginary regions remaining in the plurality of imaginary regions as translational symmetry. Therefore, even when a light reflection point is formed at a lower coverage ratio near the light source, the printing area of the light reflection point (the area where the light reflection point is formed) and the non-printing area (the light reflection point is not formed) can be reduced. The area is dark and dark. As a result, unevenness in brightness in the vicinity of the light incident portion where light is incident on the light guide plate can be suppressed.

In one embodiment, the arrangement of the light reflection points in the selected one of the imaginary regions and the light reflection points in the six or more imaginary regions of the 24 imaginary regions surrounding the selected one of the imaginary regions may be Configured to be translationally symmetric.

In this case, the regularity in the light distribution pattern including the plurality of light reflection points is improved, so that unevenness in brightness in the vicinity of the light incident portion can be suppressed.

In one embodiment, the arrangement of the light reflection points in the selected one of the imaginary regions and the light reflection in the imaginary regions of the four or more of the eight imaginary regions adjacent to the selected one of the imaginary regions may be The point configuration is translational symmetry.

In this case, the regularity in the light distribution pattern including the plurality of light reflection points is further improved, so that unevenness in brightness in the vicinity of the light incident portion can be further reduced.

In each of the plurality of imaginary regions in the embodiment, the maximum diameter among the plurality of light reflection points formed in the imaginary region is represented as D (μm), and the first arrangement in the two-dimensional array When the number of imaginary grids in the direction is expressed as L1 (number), and the number of imaginary grids in the second array direction intersecting the first array direction in the two-dimensional array is expressed as L2 (number), it may be 10 μm<D 300 μm, 2<L1 200 and 2<L2 200.

In each of the plurality of imaginary regions in one embodiment, the imaginary region can be divided into a plurality of small regions. In this case, the small area may be an area in which the number of light reflection points in the virtual area is represented as n (n>1), and the imaginary lattice of the first arrangement direction in the two-dimensional arrangement is The number is expressed as L1 (number), and the number of virtual squares in the second array direction intersecting the first array direction in the two-dimensional array is expressed as L2 (number), and the set including the common numbers of L1 and L2 is represented as N1 and N2, the elements constituting N1 and N2 are respectively denoted as N1e and N2e, X is defined as N1e×N2e-n, Y is defined as N1e+N2e, and X is 0 or more, X and Y. N1e and N2e which are the smallest are represented by N1e _min and N2e _min , and the number of virtual grids in the first array direction of the small region is expressed as M1 (number), and the number of virtual grids in the second array direction of the small region is expressed as M2. In the case of (one), M1 is L1/N1e _min and M2 is L2/N2e _min . In this embodiment, the ratio of the small region where the light reflection point is not formed in each of the plurality of imaginary regions may be 75% or less.

In each of the plurality of imaginary regions, when the ratio of the small region where the light reflection point is not formed is 75% or less, it is easy to uniformly arrange the light reflection points in the imaginary region. As a result, unevenness in brightness near the light incident portion is further lowered.

In one embodiment, the plurality of light reflection points formed on the dot formation surface may include two or more light reflection points having different sizes.

Another aspect of the invention is directed to a method of designing a light distribution pattern comprising a plurality of light reflecting points formed on at least one side of a substrate of a light guide. The design method includes a coating rate setting step of dividing a dot forming surface, which is a surface on which a light reflecting point is formed, on the light guide plate substrate at equal intervals and imaginarily dividing into a plurality of regions, and setting the covering for each imaginary region. a virtual grid setting step of setting a virtual grid to be a print target, that is, a virtual grid that is regularly arranged two-dimensionally for each virtual region; and a light reflection dot condition setting step for forming a hypothetical region based on a coverage ratio setting a size of a light reflection point on the imaginary grid and a number of light reflection points; and a light reflection point arrangement step of arranging the light reflection points in the imaginary area selected from the plurality of imaginary areas and the plurality of imaginary areas The light reflection points in at least one of the imaginary regions remaining in the middle are arranged in a translational symmetry manner, and the light reflection points are arranged on the virtual lattice in each of the imaginary regions, thereby obtaining a light distribution pattern.

In this case, the light distribution pattern including the plurality of light reflection points has a regularity of arrangement of light reflection points in at least one of the plurality of imaginary regions remaining in the plurality of imaginary regions as translational symmetry. Therefore, in the light guide plate substrate, a light guide plate having a plurality of light reflection points formed by the light distribution pattern is inserted into the light guide plate. In the vicinity of the light portion, even if the coverage of the light reflection point is set to a low coverage ratio, the difference in brightness between the printed area and the non-printed area of the light reflection point can be reduced. As a result, uneven brightness in the vicinity of the light incident portion can be reduced.

In one embodiment, in the light reflection point arrangement step, six of the 24 imaginary regions surrounding the selected one of the imaginary regions and the arrangement of the light reflection points in the selected one of the imaginary regions may be arranged. The light reflection points in the above imaginary area are arranged in a translational symmetry manner, and the light reflection points are arranged on the virtual lattice.

In this case, the regularity in the light distribution pattern including the plurality of light reflection points is improved. Therefore, in the light guide plate in which the plurality of light reflection points are formed on the light guide plate substrate by the light distribution pattern, the light entering can be reduced. The brightness near the part is uneven.

In one embodiment, in the step of arranging the light reflection points, the arrangement of the light reflection points in the selected one of the imaginary regions and the arrangement of the four imaginary regions adjacent to the selected one of the imaginary regions may be 4 The light reflection points in more than one imaginary area are arranged in a translational symmetry manner, and the light reflection points are arranged on the imaginary lattice.

In this case, the regularity of the light distribution pattern including the plurality of light reflection points is further improved, and therefore, the light guide plate in which the plurality of light reflection points are formed on the light guide plate substrate in the light distribution pattern can be further reduced. The brightness near the light entrance is uneven.

In one embodiment, after the virtual lattice setting step, a virtual region dividing step of dividing the virtual region into small regions may be provided in each of the plurality of virtual regions.

In this case, the small area may be an area in which the number of the light reflection points in the virtual area is represented as n (n>1), and the imaginary lattice of the first arrangement direction in the two-dimensional arrangement is The number is expressed as L1 (number), and the number of virtual squares in the second array direction intersecting the first array direction in the two-dimensional array is expressed as L2 (number), and the set including the common numbers of L1 and L2 is represented as N1 and N2, the elements constituting N1 and N2 are respectively denoted as N1e and N2e, X is defined as N1e×N2e-n, Y is defined as N1e+N2e, and X is 0 or more, X and Y. N1e and N2e which are the smallest are represented by N1e _min and N2e _min , and the number of the virtual grids in the first array direction of the small region is expressed as M1 (number), and the virtual grid of the second array direction in the small region is When the quantity is expressed as M2 (number), M1 is L1/N1e _min and M2 is L2/N2e _min .

By dividing the imaginary area into the small area as described above, it is possible to easily design a light distribution pattern of a plurality of light reflection points in the light guide plate which can further reduce unevenness in brightness near the light entrance portion.

In one embodiment, in the light reflection point arrangement step, the light reflection point may be disposed in the virtual lattice so that the ratio of the small area where the light reflection point is not formed may be 75% or less in each of the virtual regions.

In this case, in each of the plurality of imaginary regions, the ratio of the small region where the light reflection point is not formed is 75% or less. Therefore, it is easy to uniformly arrange the light reflection points in the imaginary region. Therefore, in the light guide plate in which the plurality of light reflection points are formed on the light guide plate substrate in the light distribution pattern, the unevenness in brightness in the vicinity of the light entrance portion can be further reduced.

In one embodiment, in the light reflection point condition setting step, the size of the light reflection point may be set to two or more. In this case, in the light reflection point arrangement step, two or more light reflection points having different sizes may be disposed.

Still another aspect of the present invention relates to a method of manufacturing a light guide plate having a light distribution pattern including a plurality of light reflection points on at least one surface of a light guide plate substrate using a printing device, the printing device having two or more arrangements There are a plurality of units for printing portions for printing, and the units are arranged in the direction in which the printing portions are arranged. The method includes a light distribution pattern designing step of designing a specific light distribution pattern by the above design method of the present invention, and a light reflection dot printing step of moving the unit to the light guide plate substrate while moving relative to the substrate The printed portion prints a light reflection point on the light guide plate substrate according to the light distribution pattern.

According to the method of manufacturing the light guide plate, a plurality of light reflection points are formed on the light guide plate substrate by the light distribution pattern designed by the design method of the present invention. Therefore, in the light guide plate manufactured by the above-described manufacturing method, even if the coverage of the light reflection point in the vicinity of the light incident portion is a low coverage ratio, the difference in brightness between the printed area and the non-printed area of the light reflection point can be reduced. As a result, uneven brightness in the vicinity of the light incident portion can be reduced.

In one embodiment, the printing portion is a nozzle, and the unit is a row An ink jet head in which a plurality of nozzles are arranged, and the light reflection point may be an ultraviolet curable inkjet ink for a light guide plate.

Still another aspect of the present invention relates to a light guide plate having a light distribution pattern designed by the above design method of the present invention. Still another aspect of the invention relates to a light guide plate manufactured by the above method for manufacturing a light guide plate of the invention.

Still another aspect of the present invention relates to an edge illumination type surface light source device comprising the light guide plate of the present invention and a light source for supplying light to a side surface of the light guide plate.

Since the surface light source device includes the light guide plate of the present invention, unevenness in brightness in the vicinity of the light incident portion can be reduced. Even if the coverage of the light reflection point near the light entrance portion is a low coverage ratio, the difference in brightness between the printed area and the non-printed area of the light reflection point can be reduced. As a result, light of a more uniform brightness can be emitted.

According to still another aspect of the present invention, a transmissive image display device includes the surface light source device of the present invention and a transmissive image display portion disposed to face an exit surface of the surface light source device.

Since the transmissive image display device includes the surface light source device of the present invention, the transmissive image display portion can be uniformly illuminated.

According to the present invention, it is possible to provide a light guide plate, a surface light source device, a transmissive image display device, a light distribution pattern design method for a light guide plate, and a light guide plate which can reduce unevenness of brightness generated in the vicinity of a light incident portion where light is incident. Production method.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Label the same symbol with the same symbol. Duplicate descriptions are omitted. The size ratio of the drawing does not necessarily match the size ratio of the description. In the description, the words "upper" and "lower" are used as convenience words based on the state shown in the drawing.

Fig. 1 is a cross-sectional view showing a transmissive image display device according to an embodiment of a light guide plate of the present invention. The transmissive image display device 100 shown in FIG. 1 mainly includes a surface light source device 20 and a transmissive image display portion 30. The surface light source device 20 is an edge illumination type surface light source device including a light guide plate 1 having a light guide plate substrate 11 and a light source 3 provided on the side of the light guide plate 1 and supplying light to the light guide plate 1.

The light guide plate substrate 11 has a substantially rectangular parallelepiped shape. The light guide plate substrate 11 has a rear surface S2 on the opposite side of the emission surface S1 and the emission surface S1, and four side surfaces S3 ₁ to S3 ₄ intersecting the emission surface S1 and the back surface S2 (see FIG. 2 ). In the present embodiment, the four side faces S3 ₁ to S3 _{4 are} substantially orthogonal to the exit surface S1 and the back surface S2. The planar shape of the light guide plate substrate 11 is not limited to a rectangular shape, and may be a square shape.

The light guide plate substrate 11 contains a light transmissive material. The material of the light guide plate substrate 11 is preferably a polyalkyl (meth) acrylate resin sheet, a polystyrene sheet or a polycarbonate resin sheet, and among them, a polymethyl methacrylate resin sheet is preferred. Material (PMMA resin sheet). The light guide plate substrate 11 may also contain diffusing particles. The surface (exit surface S1) of the light guide plate substrate 11 opposite to the surface (back surface S2) on which the light reflection point 12 is formed may be a flat surface as in the present embodiment, or may have a concavo-convex shape. Further, the thickness of the light guide plate substrate 11 is preferably 1.0 mm or more and 4.5 mm or less.

The back surface (point forming surface) S2 of the light guide plate substrate 11 may be a surface to which a liquid-repellent treatment is applied to almost the entire surface of the back surface S2. The liquid-repellent treatment applied to the back surface S2 is a liquid-repellent treatment in which the contact angle is 80 to 130 degrees when the water droplets are dropped onto the back surface S2, and preferably the liquid contact treatment is performed at a contact angle of 85 to 120 degrees, more preferably contact. The angle is from 90 degrees to 110 degrees. In this embodiment, the contact angle is static. State contact angle.

A plurality of light reflection points 12 are formed on the back surface S2 side of the light guide plate substrate 11. That is, the light guide plate 1 further has a plurality of light reflection points 12 provided on the side of the back surface S2. The maximum thickness of each of the light reflection points 12 is preferably 20 μm or less, more preferably 15 μm or less.

As shown in FIG. 2, a plurality of light reflection points 12 are arranged apart from each other on the back surface S2. The distance P between adjacent two light reflecting points 12 (for example, the distance between the top and the top of the light reflecting point 12) is larger than the diameter of the light reflecting point 12. An example of the distance between two adjacent light reflection points 12 is 10 μm or more and 1000 μm or less, preferably 25 μm or more and 500 μm or less, and more preferably 50 μm or more and 100 μm or less. Fig. 2 is a plan view showing a state in which the light guide plate is viewed from the back side. In Fig. 2, the light source 3 is shown together for convenience of explanation. As shown in FIG. 2, in order to allow the uniform planar light to be efficiently emitted from the exit surface S1, the light reflection point 12 is smaller toward the light incident portion side of the light source 3, and becomes larger as it goes away from the light source 3. The light reflection dots 12 are formed in an imaginary lattice which is regularly arranged two-dimensionally over the entire back surface S2. Therefore, the coverage of the light reflection dots 12 is lower toward the light incident portion side of the light source 3, and becomes higher as it goes away from the light source 3. Preferably, the light reflection points 12 are not connected to each other. For convenience of explanation, the size, number, and the like of the light reflection points 12 are changed in FIG. As will be described later, the number of light reflection points 12 and the light distribution pattern are adjusted so that the uniform planar light is efficiently emitted from the emission surface S1. Here, the light distribution pattern of the light reflection point 12 corresponds to the arrangement pattern of the plurality of light reflection points 12.

The light source 3 is disposed on one side of the pair of side faces S3 ₁ and S3 ₂ facing each other. The light source 3 may be a linear light source such as a Cold Cathode Fluorescent Lamp (CCFL), but is preferably a point light source such as an LED (Light Emitting Diode). In this case, as shown in FIG. 2, a plurality of point light sources are arranged along the two sides of the four sides of the light guide plate base material 11, for example, the back surface S2 of the rectangular shape. It is particularly advantageous to combine the light reflection dots 12 formed of the inkjet ink described later with the LEDs to obtain light of a natural hue.

As shown in FIG. 1, the transmissive image display unit 30 is disposed to face the light guide plate 1 on the exit surface S1 side of the light guide plate 1. The transmissive image display unit 30 is illuminated by the planar light emitted from the exit surface S1 to display an image. An example of the transmissive image display unit 30 is a liquid crystal display unit (or a liquid crystal panel) in which linear polarizing plates are disposed on both surfaces of a liquid crystal element.

In the above configuration, the light output from the light source 3 enters the light guide plate substrate 11 from the side faces S3 ₁ and S3 ₂ . The light incident on the light guide plate substrate 11 is diffused and reflected at the light reflection point 12, and is mainly emitted from the exit surface S1. The light emitted from the exit surface S1 is supplied to the transmissive image display unit 30. In order to allow the uniform planar light to be efficiently emitted from the exit surface S1, the number of light reflection points 12 and the light distribution pattern are adjusted.

Next, a light distribution pattern including a plurality of light reflection points 12 will be described. Fig. 3 is a diagram for explaining a light distribution pattern. Fig. 3 is an enlarged view of a portion of the back surface S2. In Fig. 3, in order to clearly show the light reflection point 12, the light reflection point 12 is indicated by a black dot for convenience.

As shown in FIG. 3, the back surface S2 is imaginarily divided into a plurality of imaginary areas A at equal intervals. In the present embodiment, as shown in FIG. 3, the first direction (first array direction) x and the second direction (second array direction) y which are orthogonal to each other are equal to each other. The back surface S2 is divided into intervals, whereby the back surface S2 is divided into a plurality of imaginary areas A. 3 is a view in which three × three imaginary regions A in a plurality of imaginary regions A after dividing the back surface S2 are extracted. In Fig. 3, the area distinguished by the thick solid line is the imaginary area A. Similarly, in other figures, the area distinguished by the thick solid line is also the imaginary area A.

The plurality of imaginary regions A have the same shape. In the present embodiment, the shape of the virtual area A will be described in a square shape. However, the shape of the imaginary area A may be a rectangle, or may be a parallelogram or a diamond.

Fig. 4 is a diagram for explaining a virtual area. FIG. 4 is a diagram in which one of the imaginary regions A in FIG. 3 is extracted. In each of the imaginary regions A, a plurality of imaginary lattices g (regions surrounded by broken lines) as printing targets are regularly two-dimensionally arranged. A light reflection point 12 is formed in a specific imaginary lattice g of a plurality of imaginary lattices g arranged in two dimensions. In FIG. 3, the virtual lattice g is arranged in the first direction x and the second direction y orthogonal to the first direction x, whereby the plurality of virtual lattices g constitute a two-dimensional array. One of the shapes of the imaginary lattice g is, for example, a square as shown in FIGS. 3 and 4, but may be a rectangle, and may be a parallelogram or a diamond. It is not limited to the case where the first direction x is orthogonal to the second direction y, and the first direction x may intersect with the second direction y.

The plurality of light reflection points 12 are disposed on the back surface S2 so as to satisfy the light distribution pattern of the following condition 1.

(Condition 1)

The arrangement of the light reflection points 12 in one of the imaginary areas A selected from the plurality of imaginary areas A and the arrangement of the light reflection points 12 in at least one of the remaining imaginary areas A are translationally symmetrical.

Preferably, the plurality of light reflecting points 12 are disposed on the back surface S2 so as to satisfy the light distribution pattern of the following condition 2.

(Condition 2)

Arrangement of the reflection points 12 in the imaginary area A selected from the plurality of imaginary areas A and the reflection points 12 in the imaginary area A of the six or more imaginary areas A around the imaginary area A Symmetrical for translation. The 24 imaginary areas A around the imaginary area A surround the 24 imaginary areas A of one imaginary area A by the width of two imaginary areas A.

More preferably, the plurality of light reflection points 12 are disposed on the back surface S2 so as to satisfy the following condition 3 light distribution pattern.

(Condition 3)

The arrangement of the light reflection points 12 in the imaginary area A selected from the plurality of imaginary areas A and the light reflection points 12 in the imaginary area A of the four imaginary areas A adjacent to the imaginary area A The configuration is translational symmetry.

The above-mentioned "translational symmetry" means a symmetry that overlaps with other imaginary regions A when the virtual region A of interest (or selection) is moved in parallel in the first direction x or the second direction y. In the following description, the number of imaginary regions A that are translationally symmetric with respect to the imaginary region A of interest is also referred to as a translational symmetry number. When the translational symmetry number is defined as such, the condition 2 corresponds to: in the 25 imaginary regions A arranged in a two-dimensional arrangement of 5×5, the imaginary area A in the center is assumed as the imaginary area A of interest, and 25 in two dimensions. In the imaginary area A, the number of translational symmetry with respect to the imaginary area A of interest is six or more. Similarly, the condition 3 corresponds to the imaginary area A in the center of the nine imaginary areas A arranged in two dimensions of 3 × 3 as the imaginary area A of interest. The number of translational symmetry of the imaginary area A of interest in the nine imaginary areas A of the two-dimensional arrangement is four or more.

In FIG. 3, a plurality of light reflecting points 12 are arranged such that the arrangement of the light reflecting points 12 in the imaginary area A and the arrangement of the light reflecting points 12 in all other imaginary areas A are translationally symmetrical. As a result, the above condition 3 is satisfied. Therefore, the mode shown in Fig. 3 also satisfies the conditions 1, 2.

An example of the relationship between the size of the imaginary area A and the size of the light reflection point 12 is as follows.

That is, in one embodiment, the largest diameter among the plurality of light reflection points 12 formed in the virtual area A is represented by D (μm), and the number of the virtual lattices g of the first direction x in the two-dimensional arrangement When the number of the virtual grids g in the second direction y in the two-dimensional array is expressed as L2 (number), the size of the light reflection point 12 and the size of the virtual area A satisfy the following three expressions ( 1a), (1b), (1c).

[Number 1] 10 μm<D≦300 μm (1a) 2<L1≦200...(1b) 2<L2≦200...(1c)

Further, the above D is preferably 20 μm or more and 200 μm or less, and more preferably 30 μm or more and 100 μm or less.

In the embodiment, when the virtual area A is divided into a plurality of small areas B, the ratio of the light reflection points 12 not formed in the small area B can be set to 75% or less. Here, the small area B is an element area constituting the virtual area A. The small area B is an area set as follows.

When the number of light reflection points 12 in the imaginary area A is represented by n (n>1), the number of imaginary lattices g in the first direction x is represented as L1 (number), and the number of imaginary lattices g in the second direction y Expressed as L2(s), the set of common divisors including L1 and L2 is denoted as N1 and N2, respectively. When the elements constituting N1 and N2 are represented as N1e and N2e, X is defined as N1e×N2e-n, and Y is defined. It is N1e+N2e. Further, under the condition that X is 0 or more, N1e and N2e where X and Y are the smallest are represented by N1e _min and N2e _min , and the number of virtual lattices g of the first direction x of the small region B is expressed as M1 (number). When the number of the imaginary lattices g in the second direction y of the small region B is expressed as M2 (number), M1 is L1/N1e _min and M2 is L2/N2e _min . Therefore, the number of the virtual lattices g in the small region B in the first direction x is M1 (number), and the number of the virtual lattices g in the second direction y is the region of M2 (number).

The configuration of the small area B will be specifically described with respect to the case of the virtual area A illustrated in Fig. 4 . In Fig. 4, the small area B is an area surrounded by thin solid lines. In the imaginary area A, n=9, and L1=L2=6. Therefore, N1=N2={1, 2, 3, 6}. The element N1e of N1 is the number selected from 1, 2, 3, and 6. The element N2e of N2 is the number selected from 1, 2, 3, and 6. In the combination of N1e and N2e selected from {1, 2, 3, 6}, the combination of N1e and N2e where X and Y are the smallest is N1e=N2e=3 under the condition that X is 0 or more. That is, N1e _min and N2e _min are 3. In this case, M1 and M2 are 2. Therefore, the small area B is a region in which the virtual lattices g in the first direction x and the second direction y are two. In the imaginary area A illustrated in FIG. 4, in order to indicate the size of the small area B, hatching is applied to one small area B, and the imaginary area A includes nine small areas B. In the imaginary area A illustrated in FIG. 4, each small area B includes the light reflection point 12, and therefore the ratio of the light reflection point 12 which is not formed in the small area B is 0%.

Next, an example of a method of manufacturing the light guide plate of the present embodiment will be described. Fig. 5 is a flow chart showing a method of manufacturing a light guide plate. As shown in FIG. 5, when manufacturing the light guide plate, the light distribution pattern designing step S10 of designing a light distribution pattern of a plurality of light reflection points formed on the light guide plate; and designing in the light distribution pattern design step S10 A light reflection dot printing step S20 of forming a plurality of light reflection points 12 on the light guide substrate 11 by the light distribution pattern. First, the light distribution pattern designing step S10 will be described.

In the light guide plate 1, the dot formation surface on which the light reflection point 12 is formed is imaginarily divided into a plurality of imaginary regions A at equal intervals, and the coverage ratio is set for each imaginary region A (the coverage ratio setting step S11). In the present embodiment, the dot formation surface is divided into a plurality of virtual regions A by dividing the first direction x and the second direction y which are orthogonal to each other at equal intervals as described above. In the present embodiment, the dot formation surface corresponds to the back surface S2. The number of imaginary areas A and the coverage ratio are set so as to emit uniform light from the exit surface S1.

Then, a virtual grid g serving as a print target, that is, a virtual grid g that is regularly two-dimensionally arranged is set for each virtual region A (hypothetical lattice setting step S12). In the present embodiment, the virtual region G is divided and further divided in the first direction x and the second direction y, and the virtual lattice g is set and obtained.

Then, for each imaginary area A, the size of the light reflection point 12 formed on the virtual lattice g and the number of light reflection points 12 are set based on the coverage ratio (light reflection point condition setting step S13). An example of the size of the light reflecting point 12 may be the diameter of the light reflecting point 12.

Then, an imaginary area A selected from a plurality of imaginary areas A The arrangement of the light reflection points 12 in the interior and the light reflection points 12 in at least one of the imaginary areas A of the remaining imaginary areas A are arranged in a translational symmetry manner, and light is emitted in each imaginary area A. The reflection point 12 is placed on the virtual lattice g, thereby obtaining a light distribution pattern (light reflection point arrangement step S14). In other words, the light reflection point 12 is placed on the virtual lattice g in each of the virtual regions A so as to satisfy the above condition 1. At this time, it is preferable to arrange the light reflection point 12 so as to satisfy the above condition 2. It is more preferable to arrange the light reflection point 12 so as to satisfy the above condition 3.

In one embodiment, after the virtual grid setting step S12, a virtual region dividing step of dividing the virtual region A into the small region B among the plurality of virtual regions A may be provided. The small area B is as described above, and the number of virtual grids g in the first direction x is M1 (number), and the number of virtual grids in the second direction is M2 (number). As described above, when the virtual area A is further divided into the small areas B, in the light reflection point arrangement step S14, the ratio of the small area B in which the light reflection points 12 are not formed may be 75 in the virtual area A. The light reflection point 12 is configured in the following manner. Furthermore, the virtual region dividing step may be performed after the virtual lattice setting step S12. For example, the hypothetical region segmentation step can be performed within the light reflection point configuration step.

In one embodiment, the size of the light reflecting point 12 and the size of the imaginary area A can be designed to satisfy the equations (1a) to (1c).

In the light reflection point condition setting step S13, the size of the light reflection point 12 may be set to two or more (two patterns) or more. In this case, in the light reflection point arrangement step S14, two or more kinds of light reflection points 12 having different sizes may be regularly arranged or irregularly arranged.

Then, a plurality of light reflection points 12 are printed on the dot formation surface S2 in accordance with the light distribution pattern obtained by the light distribution pattern designing step S10. Fig. 6 is a schematic view showing a manufacturing apparatus of a light guide plate 1 including a printing apparatus for printing a light reflection point.

The manufacturing apparatus 200 includes a transport mechanism 40 that transports the light guide plate substrate 11 , an inkjet head 5 , a UV lamp 7 , and an inspection device 9 . The ink jet head 5, the UV lamp 7, and the inspection device 9 are arranged in this order from the upstream side in the moving direction U of the light guide plate substrate 11. The ink jet head 5 and the UV lamp 7 correspond to a printing device of the light reflecting point 12.

The light guide plate substrate 11 is continuously or intermittently conveyed in the direction U by the transport mechanism 40. The light guide plate substrate 11 can also be previously cut according to the size of the light guide plate to be manufactured. Alternatively, the light reflection point 12 may be formed on the long light guide substrate 11 and then the light guide substrate 11 may be cut. The conveying mechanism 40 in the present embodiment is a table shuttle, but the conveying mechanism is not limited to the moving table. The transport mechanism may be, for example, a transport belt, a roller, or an air floating transport.

On the dot forming surface S0 of the light guide plate substrate 11 which forms the light reflection point 12, the inkjet ink 5 supported by the support portion 41, the inkjet ink of the droplet shape is designed in the design step S10. The light pattern is printed in a dot pattern. At this time, the pattern printing is performed in such a manner that the droplet-shaped inkjet ink dropped on the dot formation surface S0 is separated from each other.

The ink jet head 5 is formed over the entire width direction (the direction perpendicular to the direction U) of the region where the light reflecting point 12 of the spot forming surface S0 of the light guide plate substrate 11 is formed, and has a surface S0 with the point of the light guide substrate 11 (back S2) opposite to ground A plurality of nozzles of one or more columns are arranged in a fixed manner. The droplet-shaped ink ejected by the inkjet method from the specific nozzles of the plurality of nozzles is printed together at the same time in the width direction of the light guide substrate 11 as a whole. It is preferable to print the ink while continuously moving the light guide plate substrate 11 at a constant speed. Alternatively, the mode in which the ink is printed in a state where the light guide plate substrate 11 is stopped and the mode in which the light guide plate substrate 11 is moved to the next printing position are repeated, and the pattern including the dots of the plurality of columns can be efficiently printed. ink. The above specific nozzle for ejecting ink is controlled in accordance with the light distribution pattern.

The moving speed of the light guide plate substrate 11 is adjusted in such a manner as to appropriately print the ink. In the case of the present embodiment, as shown in Figs. 6 and 7, the ink jet head 5 includes a plurality of ink jet heads (units) 5a to 5c each having a plurality of nozzles 51. Fig. 7 is a view showing the ink jet head from the ejection side of the ink. The ink jet head 5a is illustrated in Fig. 7, but the ink jet heads 5b and 5c are also the same. The plurality of ink-jet heads 5a to 5c are arranged in a direction orthogonal to the direction U in which the light-guide plate substrate 11 is conveyed, and are connected to each other at the end portions in the transport direction U via the fixing member 52 (see FIG. 6). .

In the case of the present embodiment, the ink can be printed together in the entire width direction of the light guide plate substrate 11 in a state in which a plurality of nozzles of the ink jet head 5 are fixed. As a result, the productivity of the light guide plate 1 is drastically improved as compared with the case where the ink is sequentially printed while moving the movable nozzle along the width direction of the light guide plate substrate 11.

In particular, in the case of manufacturing a large light guide plate 1 having a short side of the light guide plate substrate 11 of 200 mm or more and 1000 mm or less, the method of the present embodiment The effect of improving productivity is greater. Further, according to the inkjet method, even a minute light reflection point 12 having a maximum diameter of 100 μm or less can be easily and accurately formed. When the light guide plate substrate 11 is thin, there is a possibility that the light reflection point 12 penetrates from the exit surface S1 side and is seen. By reducing the light reflection point 12, the light reflection point 12 can be prevented from being emitted from the exit surface S1. The situation where the side is penetrated and is seen.

The nozzle of the inkjet head 5 is coupled to the ink supply unit 50 via a conduit 55. The ink supply unit 50 has, for example, an ink tank that stores ink and a pump that sends out ink. The plurality of conduits 55 can be coupled to a single ink reservoir or to a plurality of ink reservoirs.

In order to form the light reflection dots 12, the inkjet ink used for inkjet printing may be an ultraviolet curable ink containing a pigment, a photopolymerizable component, or a photopolymerization initiator, or may be an aqueous ink or a solvent ink. Further, the inkjet ink may not necessarily contain a pigment.

The pigment is preferably at least any one of calcium carbonate particles, barium sulfate particles, and titanium dioxide particles. The cumulative 50% particle diameter D50 of each of the calcium carbonate particles, the barium sulfate particles, and the titanium dioxide particles is 50 to 3000 nm, more preferably 100 to 1,500 nm, and still more preferably 300 to 600 nm. Calcium carbonate particles, barium sulfate particles, and titanium dioxide particles having a cumulative 50% particle diameter D50 in the range of 50 to 3000 nm can be obtained by appropriately selecting a particle size distribution from a commercial product. The cumulative 50% particle diameter D50 is measured by measuring the particle diameter and volume of all the particles, and when the particles are sequentially accumulated from the small particle diameter, the particle diameter of the particles at the time when the cumulative volume is 50% with respect to the total volume of all the particles. The proportion of pigment in ink It is usually about 0.5 to 15.0% by mass based on the total mass of the ink. An ink using a pigment of at least one of calcium carbonate particles, barium sulfate particles, and titanium dioxide particles is an ink using an inorganic substance. In consideration of the storage stability of the inorganic ink, that is, the sedimentation property of the inorganic pigment, it is more preferable to use, as the ink, calcium carbonate particles having the smallest specific gravity among the three kinds of particles as the pigment.

The viscosity of the inkjet ink at 50 ± 10 ° C is preferably 5.0 to 15.0 mPa ‧ s, more preferably 8.0 to 12.0 mPa ‧ s. The viscosity of the inkjet ink can be adjusted, for example, by the weight average molecular weight and/or the content ratio of the aliphatic (meth) acrylate. When the weight average molecular weight and the content ratio of the aliphatic (meth)acrylic acid urethane are large, the viscosity of the ink tends to increase.

The surface tension of the inkjet ink at 25.0 ° C is preferably 25.0 to 45.0 mJ/m ² , more preferably 25.0 to 37.0 mJ/m ² . The surface tension of the inkjet ink can be adjusted, for example, by blending a surfactant such as a lanthanide system or a fluorine-based ink with an ink.

The printed ink is hardened in the region 70 by the UV lamp 7 supported by the support portion 42. Thereby, a light reflection point 12 including the cured ink is formed. That is, the light reflection point 12 is printed on the dot formation surface S0.

Thereafter, the light guide plate 1 is obtained by the step of inspecting the state of the formed light reflection point 12 by the inspection device 9 supported by the support portion 43. The light guide plate 1 is cut to a desired size as needed. As in the present embodiment, it is not always necessary to continuously inspect the light guide plate 1 by the inspection device 9 provided on the downstream side of the inkjet head 5, and the light guide plate can be inspected offline by using an inspection device prepared separately. Alternatively, the light guide plate executed by the inspection device may be omitted 1 check.

The plurality of light reflection points 12 included in the light guide plate 1 shown in FIG. 1 and FIG. 2 are disposed on the back surface S2 in the light distribution pattern designing in the light distribution pattern designing step S10. Therefore, as described with reference to FIG. 3, when the back surface S2 is divided into a plurality of imaginary areas A, a plurality of light reflection points 12 are arranged in the light distribution pattern satisfying the condition 1.

That is, the plurality of light reflecting points 12 are arranged such that the light reflecting point 12 in the imaginary area A arbitrarily selected from the plurality of imaginary areas A and the light reflecting point 12 in at least one of the imaginary areas A in the remaining imaginary area A The configuration is translational symmetry, and the regular light distribution pattern is formed on the back surface S2.

From the viewpoint of uniform brightness of the light emitted from the exit surface S1, generally, in the light guide plate 1, the coverage of the light reflection point 12 is set to be low, for example, in the vicinity of the light incident portion from which the light from the light source 3 is incident. It is about 5%. Therefore, as exemplified in Fig. 2, the diameter of the light reflection point 12 on the side of the side faces S3 ₁ and S3 ₂ (near the light entrance portion) is usually small. This is more apparent when the light reflection point 12 is formed by ink jet printing which can further reduce the diameter.

In this way, when the light reflection point 12 is arranged in a regular manner as described above in the vicinity of the light source 3 having a small coverage and a smaller diameter of the light reflection point 12, the printing area where the light reflection point 12 is printed and the non-printing are printed. The difference in the size of the area is reduced. Therefore, the difference in brightness between the printing area and the non-printing area is small, and as a result, unevenness in brightness such as smoke in the vicinity of the light entering portion where light from the light source 3 is incident can be suppressed.

The light distribution pattern satisfying the condition is configured in a pattern in which a plurality of light reflection points 12 are arranged. In the case of 2 and condition 3, the regularity in the light distribution pattern increases. Therefore, the difference in brightness between the printed area and the non-printed area is further reduced. For Condition 2 and Condition 3, the regularity in the light distribution pattern of the light distribution pattern satisfying Condition 3 is further improved. As a result, compared with the case of the condition 2, it is possible to suppress unevenness in luminance of the light guide plate 1 in which the plurality of light reflection points 12 are formed in the vicinity of the light source by using the light distribution pattern satisfying the condition 3.

When the virtual region A is further divided into a plurality of small regions B, the ratio of the small region B in which the light reflection dots 12 are not formed is 75% or less, and it is easy to uniformly arrange the light in the virtual region A. Reflection point 12. As a result, in the light guide plate 1, the unevenness in brightness in the vicinity of the light incident portion into which the light from the light source 3 is incident can be further reduced.

In the case where the light distribution pattern designing step S10 includes the step of dividing the virtual region A into the small region B, as described above, the light guide plate 1 can further reduce the plurality of lights having uneven brightness in the vicinity of the light incident portion. The design of the light distribution pattern of the reflection point 12 becomes easier.

Further, when there are two or more kinds of the light reflection dots 12, the luminance change caused by the light reflection dots 12 can be reduced. As a result, unevenness in brightness in a region of low coverage ratio in the vicinity of the light source 3 can be further suppressed.

As described above, in the light guide plate 1, the unevenness in brightness in the vicinity of the light incident portion is lowered, so that the surface light source device 20 shown in Fig. 1 can emit light having a more uniform brightness. Therefore, the transmissive image display portion 30 in the transmissive image display device 1 can be illuminated more uniformly.

[Examples]

The light guide plate 1 according to the embodiment of the present invention is tested as an embodiment. A comparison evaluation with the light guide plate of the comparative example was carried out. The light guide plates of the examples and the comparative examples are as follows.

(Example 1)

A 923 mm × 540 mm PMMA (polymenthyl methacrylate) resin sheet was prepared as a light-transmitting resin sheet, and a light-shielding plate was produced using a UV-curable inkjet ink containing calcium carbonate as a pigment.

Specifically, the light distribution pattern is designed according to the flowchart shown in FIG. In the coverage ratio setting step S11, the back surface S2 is divided into a plurality of imaginary regions A having a square of 507 μm on one side, and the coverage ratio of each imaginary region A is set to 3.4%. Then, in the lattice setting step S12, the virtual lattice g serving as the printing target of the light reflection point 12 is set to 6 × 6 for each virtual area A. In this step, 36 imaginary lattices g are regularly two-dimensionally arranged. In the virtual area A, the number (L1) of the virtual lattices g in the first direction x is six, and in the virtual area A, the number (L2) of the virtual lattices g in the second direction y is also six. Then, in the light reflection point condition setting step S13, the diameter of the light reflection point 12 is set to 35 μm based on the coverage ratio of 3.4%, and the number of light reflection points 12 is set to nine for each imaginary area A. . Then, in the light reflection point arrangement step S14, the light reflection point 12 is placed in the virtual area A such that the light reflection point 12 in each virtual area A is in the state shown in FIG. In this case, the light distribution pattern including the plurality of light reflection points 12 designed in Embodiment 1 corresponds to the light distribution pattern including the plurality of reflection points 12 shown in FIG.

In the first embodiment, in all the imaginary areas A, the light reflection points 12 are arranged as shown in FIG. Therefore, when focusing on a hypothetical area A, The number of translational symmetry in the eight imaginary regions A adjacent to the imaginary region A is 8. Further, the number of translational symmetry of the 24 imaginary regions A surrounding the virtual region A of interest with respect to the imaginary region A of interest is 24.

As described with reference to FIG. 4, when the concept of the small area B in which the virtual area A is further divided is introduced in the first embodiment, L1 = L2 = 6, and the number (n) of the light reflection points 12 is nine. Therefore, N1e _min = N2e _min = 3. In addition, as described above, N1e _min and N2e _min are under the condition that X (= N1e × N2e - n) of the elements N1e and N2e including the set N1 and N2 of the common divisors of L1 and L2 is 0 or more. , X and Y (=N1e+N2e) are the smallest N1e and N2e. Since L1 = L2 = 6, and N1e _min = N2e _min = 3, the number (M1) of the virtual lattices g constituting the first direction x of the small region B is two, and the imaginary lattice constituting the second direction y of the small region B The number of g (M2) is also two. Embodiment 1 has light reflection dots 12 formed in all of the small regions B. As a result, if the ratio of the small area B in which the light reflection point 12 is not formed is set to R (%), R=0. Hereinafter, the above "proportion" is also referred to as a ratio R.

Then, the mask film was peeled off from the PMMA resin sheet, and the light distribution pattern obtained on the surface on which the mask film was peeled off was ink-jet-printed by the ultraviolet curable inkjet ink. As the ink jet head, an ink jet head having an inter-nozzle distance d1 of about 84.5 μm was used (see Fig. 6). The light distribution pattern was printed on a 60 mm × 500 mm area of the 923 mm × 540 mm surface of the PMMA resin sheet.

Then, the inkjet ink after printing is irradiated with ultraviolet rays, and the ink is photohardened. Specifically, after the UV-curable inkjet ink is patterned on the PMMA resin sheet, the ultraviolet light is irradiated after 6 seconds, and the ink is lighted. hardening. As a result, the light guide plate of Example 1 in which the light distribution pattern in which the light reflection dots 12 are regularly arranged is obtained.

(Examples 2 to 5)

The light guide plates of Examples 2 to 5 were obtained in the same manner as in Example 1 except that the arrangement of the light reflection points 12 in the virtual area A was changed.

8(a) to 8(d) are diagrams showing the arrangement of the light reflection points 12 in the virtual region A in the second to fifth embodiments. The differences from Embodiment 1 in Embodiments 2 to 5 will be described using the concept of small area B. In FIGS. 8(a) to 8(d), in order to indicate the size of the small area B, a small area B is hatched in the same manner as in the case of FIG. In the other figures, a small area B is also hatched in the same manner.

In the second embodiment, the arrangement of the light reflection points 12 in the small area B is changed as shown in Fig. 8(a). In the second embodiment, the light reflection points 12 are disposed in all of the small areas B in the virtual area A. Therefore, in the same manner as in the first embodiment, the ratio R of the small region B in which the light reflection point 12 is not formed is 0%.

In the third embodiment, the arrangement of the light reflection points of the small area B in the virtual area A is changed as shown in Fig. 8(b). In the third embodiment, the ratio R of the small region B in which the light reflection point 12 is not formed is 33.3%.

In the fourth embodiment, the arrangement of the light reflection points of the small area B in the virtual area A is changed as shown in Fig. 8(c). In the fourth embodiment, the ratio R of the small region B in which the light reflection point 12 is not formed is 55.6%.

In the fifth embodiment, the arrangement of the light reflection points of the small area B in the virtual area A is changed as shown in Fig. 8(d). In the fifth embodiment, the ratio R of the small region B in which the light reflection point 12 is not formed is 66.7%.

(Comparative Example 1)

In the flowchart shown in FIG. 5, in the same manner as in the first embodiment, the coverage ratio setting step S11, the grid setting step S12, and the light reflection point condition setting step S13 are performed. Thereafter, the light distribution point of the light reflection point is designed by randomly assigning a light reflection point to the virtual lattice g by using a random number. A light guide plate was obtained in the same manner as in Example 1 except that the light distribution pattern of the light reflection point thus designed was used.

(Example 6)

In the sixth embodiment, the coverage ratio was changed to 1.9%, and the number (n) of the light reflection points 12 in the virtual area A was changed to five. As the number (n) of the light reflection points 12 is changed, the arrangement of the light reflection points 12 in the virtual area A is changed as shown in Fig. 9(a). Fig. 9(a) is a view showing the arrangement of the light reflection points 12 in the virtual area A in the sixth embodiment. In the sixth embodiment, the number (n) of light reflection points 12 in the virtual area A is five, and L1 and L2 are six in the same manner as in the first embodiment, so that the combination of N1e _min and N2e _min is (2, 3). ) or (3, 2). In Example 6, it is assumed that N1e _min = 2 and N2e _min = 3. Therefore, when the concept of the small area B is introduced in the same manner as in the first embodiment, the number (M1) of the virtual lattices g in the first direction x constituting the small area B in the sixth embodiment is three, and the second direction y is assumed. The number of lattices g (M2) is two. In Example 6, the ratio R of the small region B in which the light reflection point was not formed was 16.7%.

(Example 7)

The light guide plate of Example 7 was obtained in the same manner as in Example 6 except that the arrangement of the light reflection points 12 in the virtual area A was changed. The difference from the sixth embodiment will be explained using the concept of the small area B.

In the seventh embodiment, the arrangement of the light reflection points 12 of the small area B in the virtual area A is changed as shown in Fig. 9(b). Fig. 9(b) is a view showing the arrangement of the light reflection points 12 in the virtual area A in the seventh embodiment. In the seventh embodiment, the ratio R of the small region B in which the light reflection point 12 is not formed is 83.3%.

(Comparative Example 2)

In the same manner as in the first embodiment, in the case of the comparative example 1, the second comparative example 2 was obtained in the same manner as in the sixth embodiment except that the arrangement of the five light reflection points 12 in the virtual area A was randomly arranged using random numbers. Light guide plate.

(Example 8)

In the eighth embodiment, the coverage ratio was changed to 1.5%, and the number of light reflection points 12 in the virtual area A was changed to four. As the number of light reflection points 12 changes, the light distribution pattern of the light reflection point 12 is changed as shown in Fig. 10(a). Fig. 10(a) is a view showing the arrangement of the light reflection points 12 in the virtual area A in the eighth embodiment. In Example 8, N1e _min = N2e _min = 2. When the concept of the small area B is introduced in the same manner as in the first embodiment, the number (M1) of the virtual lattices g constituting the first direction x of the small area B in the eighth embodiment is three, and the second direction y The number of imaginary lattices g (M2) is also three. In the eighth embodiment, the ratio R of the small region B in which the light reflection point 12 is not formed is 0%. The light guide plate of Example 8 was obtained in the same manner as in Example 1 except that the coverage ratio and the light distribution pattern were changed.

(Example 9)

The light guide plate of Example 9 was obtained in the same manner as in Example 8 except that the arrangement of the light reflection points 12 in the imaginary area A was changed. For the difference from the eighth embodiment, the concept of the small area B will be described. In the embodiment 9 The arrangement of the light reflection points 12 of the small area B in the imaginary area A changes as shown in Fig. 10(b). Fig. 10(b) is a view showing the arrangement of the light reflection points 12 in the virtual area A in the ninth embodiment. In the ninth embodiment, the ratio R of the small region B in which the light reflection dots 12 were not formed was 75.0%.

(Comparative Example 3)

In the same manner as in the case of the first embodiment, the arrangement of the four light diffusion points in the virtual region A was randomly arranged using a random number, and the comparative example 3 was obtained in the same manner as in the eighth embodiment. Light guide plate.

(Embodiment 10)

In the tenth embodiment, the same as in the case of the first embodiment except that the nine virtual regions A shown in FIG. 11 are used as one unit and the cells are arranged in two dimensions to obtain a light distribution pattern. Light guide plate. In FIG. 11, the nine imaginary areas A are referred to as imaginary areas A _i,j (1) based on the upper left imaginary area A. i 3, 1 j 3). The imaginary regions A _1,1 , A _1,3 , A _2,2 , A _3,1 , A _3,3 are the same as the imaginary region A in the first embodiment. The other imaginary regions A ₁ , ₂ , A ₂ , ₁ , A ₂ , ₃ , and A ₃ , ₂ are designed under the same conditions as the imaginary region A of the first embodiment except that the arrangement of the light reflection points 12 is changed. The imaginary area. In the unit shown in FIG. 11, if attention is paid to the central imaginary area A ₂ , ₂ , the imaginary area A _{2, 2} and the four imaginary areas A _1,1 , A _1,3 , A _3,1 , A _{3, 3} is translational symmetry. Figure 11 comprising the nine cells of the virtual area A 2-dimensional arrayed embodiment of the light guide plate 10 of the embodiment, when the attention of the virtual area A in FIG. _{2,2 &} 11 As shown, in the region surrounding the virtual _{2,2 &} A In the 24 imaginary areas A, the imaginary area A _{2, 2} and the 16 imaginary areas A are translationally symmetric.

(Example 11)

In the eleventh embodiment, the virtual area A is designed as shown in Figs. 12(a) to 12(e). The virtual area A of Fig. 12(a) is the same as the virtual area A of the first embodiment. The imaginary area A shown in FIGS. 12(b) to 12(e) is different from the imaginary area A of the first embodiment except that the arrangement of the light reflection points 12 is different. For convenience of explanation, the virtual regions A of FIGS. 12(a) to 12(e) are referred to as virtual regions A1, A2, A3, A4, and A5, respectively. The light guide plate of the eleventh embodiment has a light distribution pattern in which three virtual regions A are arranged in the first direction x and the second direction y as a unit area, and the unit regions are arranged in two dimensions. In the light distribution pattern of the light guide plate of the eleventh embodiment, one virtual area A1, two imaginary areas A2, two imaginary areas A3, three imaginary areas A4, and one imaginary are randomly arranged in each unit area. Area A5.

Figure 13 is a diagram showing one of a plurality of unit areas. Similarly to the case of Fig. 11, the imaginary area A on the upper left is used as a reference, and the nine imaginary areas A are referred to as imaginary areas A _i,j (1, respectively). i 3, 1 j 3).

The correspondence relationship between the nine virtual regions A in the unit area shown in Fig. 13 and the virtual regions A1 to A5 shown in Figs. 12(a) to 12(e) is as follows. The imaginary area A _1,1 corresponds to the imaginary area A5. The imaginary areas A ₁ , ₂ , A ₃ , ₂ correspond to the imaginary area A2. The imaginary areas A ₁ , ₃ , A ₂ , ₃ , and A ₃ , ₁ correspond to the imaginary area A4. The imaginary areas A _2,1 , A _3,3 correspond to the imaginary area A3. The imaginary area A _{2, 2} corresponds to the imaginary area A1.

In each unit area, the imaginary areas A1 to A5 are randomly arranged in the above-described number. Therefore, for example, the light distribution pattern in the other unit area adjacent to the unit area shown in FIG. 13 is as shown in FIG. Light distribution map in the unit area The case is different.

(evaluation method and evaluation result)

In the present invention, a light guide plate of Examples 1 to 11 and Comparative Examples 1 to 3 was incorporated in a television unit using a LED as a light source (BRAVIA (KDL-40EX700) manufactured by Sony Corporation), instead of the light guide plate mounted on the television unit. . Further, in a state in which one of the diffusion films mounted on the television unit is provided on the light guide plate, the television unit is turned on, and the brightness unevenness in the vicinity of the light source (light entrance portion) is visually evaluated, and the luminance measurement is performed.

The brightness is measured by aligning the CA-2000 manufactured by Konica Minolta with the diffusion film and measuring it within a range of 400 × 300 pixels. With this measurement, a luminance distribution of 300 points of 400 points was obtained. The approximate distribution of the primary function is calculated for each luminance distribution. The slope of the approximation curve is fixed, and thus corresponds to an ideal luminance distribution in which luminance unevenness does not exist. In the evaluations of Examples 1 to 11 and Comparative Examples 1 to 3, the deviation between the calculated approximate curve and the luminance distribution as the measurement result was evaluated by the following equation.

In the formula (2), k is the number of the measurement point. Q _k is the measured value of the kth measurement point. q _k is the estimated value of the approximate curve based on the kth measurement point. When the deviation is defined by the formula (2), the larger the deviation, the greater the unevenness in brightness.

The evaluation results of Examples 1 to 5 and Comparative Example 1 are shown in Fig. 14 . The evaluation results of Examples 6, 7 and Comparative Example 2 are shown in Fig. 15. The evaluation results of Examples 8, 9 and Comparative Example 3 are shown in Fig. 16. Evaluation of Examples 10 and 11 The result is shown in Fig. 17. In the graphs shown in Figs. 14 to 17, the design conditions of the alignment patterns of the light reflection points of the above-described Examples 1 to 11 and Comparative Examples 1 to 3 are shown together.

The "n()" in the graphs of Figs. 14 to 17 is the number of light reflection points 12 in the imaginary area A. Chart 14 to 17 of in the "N1e _min" "N2e _min" and "M1", when "M2" and into which case the concept of the small region B is illustrated the "N1e _min" "N2e _min" and "M1" and "M2" are the same. "N ₈ " in the graphs of Figs. 14 to 17 indicates that a virtual area A is focused on, and the number of imaginary areas A in the imaginary area A adjacent to the imaginary area A and the imaginary area A of interest is translationally symmetrical. . "N ₂₄ " in the graphs of FIGS. 14 to 17 indicates the number of imaginary regions A that are concerned with one imaginary region A and the imaginary regions A surrounding the imaginary region A that are symmetrical with respect to the imaginary region A of interest. In the eleventh embodiment, in each of the plurality of unit regions, the virtual regions A1 to A5 shown in FIGS. 8(a) to 8(e) are randomly arranged in the above-described number, and thus N ₈ is omitted. Record of N ₂₄ . The "ratio R (%)" in the graphs of Figs. 14 to 17 indicates the ratio of the small region B in which the light reflection point is not formed. The "deviation" in the graphs of Figs. 14 to 17 is the deviation defined by the formula (2).

For the visual results shown in FIG. 14 to FIG. 17, in the vicinity of the light incident portion of the light guide plate, the case where the brightness of the soot-like shape is not visually observed is represented by "○", and the case where the brightness is uneven is visually observed. ×” to indicate.

As shown in the evaluation results shown in Figs. 14 to 17, the haze-like luminance unevenness was not visually observed in Examples 1 to 11, but luminance unevenness was apparently produced in Comparative Examples 1 to 3. In addition, the light distribution pattern at the light reflection point 12 is different. In 1 to 11, the deviation from the approximate curve was small as compared with the case of Comparative Examples 1 to 3. Therefore, it can be understood that by arranging the light reflection points 12 by the light distribution pattern designed by the light distribution pattern designing step S10 of FIG. 5, it is possible to reduce the haze-like brightness unevenness in the vicinity of the light entrance portion.

The embodiments and examples of the present invention have been described above, but the present invention is not limited to the above embodiments and examples. For example, in addition to inkjet printing, light reflection dots can also be formed by screen printing.

1‧‧‧Light guide plate

3‧‧‧Light source

5‧‧‧Inkjet head

5a, 5b, 5c‧‧‧ Inkjet nozzles (units)

7‧‧‧UV lamp

9‧‧‧Inspection device

11‧‧‧Light guide plate substrate

12‧‧‧Light reflection point

20‧‧‧ surface light source device

30‧‧‧Transmission type image display unit

40‧‧‧Transportation agency

41, 42, 43‧‧‧Supported Department

50‧‧‧Ink supply unit

51‧‧‧Nozzles

52‧‧‧Fixed components

55‧‧‧ catheter

70‧‧‧ area

100‧‧‧Transmissive image display device

200‧‧‧ manufacturing equipment

A, A1, A2, A3, A4, A5, A _1,1 , A _1,2 , A _1,3 , A _2,1 , A _2,2 , A _2,3 , A _3,1 , A _{3, 2} , A ₃ , ₃ ‧ ‧ imaginary area

B‧‧‧Small area

g‧‧‧Imaginary lattice

S0‧‧‧ point forming surface

S1‧‧‧ outgoing surface

S2‧‧‧Back

S3 ₁ , S3 ₂ , S3 ₃ , S3 ₄ ‧‧‧ side

P‧‧‧ spacing

U‧‧ Direction

X‧‧‧1st direction

Y‧‧‧2nd direction

Fig. 1 is a cross-sectional view showing a transmissive image display device according to an embodiment of a light guide plate of the present invention.

Fig. 2 is a plan view showing a state in which the light guide plate is viewed from the back side.

Figure 3 is a partially enlarged view of the back side of the light guide plate.

Figure 4 is a schematic diagram of a hypothetical area.

Fig. 5 is a flow chart showing an embodiment of a method of manufacturing a light guide plate of the present invention.

Fig. 6 is a schematic view showing a manufacturing apparatus of a light guide plate 1 including a printing apparatus for printing a light reflection point.

Fig. 7 is a view showing the ink jet head from the discharge side of the liquid droplet.

Fig. 8(a) is a view showing the arrangement of light reflection points in the imaginary region in the second embodiment. (b) is a diagram showing the arrangement of light reflection points in the imaginary region in the third embodiment. (c) is a diagram showing the arrangement of light reflection points in the imaginary area in the fourth embodiment. (d) is a diagram showing the arrangement of light reflection points in the imaginary region in the fifth embodiment.

Figure 9(a) shows the arrangement of light reflection points in the imaginary area in the sixth embodiment. The pattern. (b) is a diagram showing the arrangement of light reflection points in the imaginary region in the seventh embodiment.

Fig. 10 (a) is a view showing the arrangement of light reflection points in the imaginary region in the eighth embodiment. (b) is a diagram showing the arrangement of light reflection points in the imaginary area in the ninth embodiment.

Fig. 11 is a view showing a light distribution pattern of a plurality of light reflection points in the tenth embodiment.

12(a) to 12(e) are diagrams showing an arrangement example of light reflection points in a virtual region in the eleventh embodiment.

Fig. 13 is a view showing an example of the arrangement of the imaginary regions shown in Fig. 12 in the light distribution pattern of the eleventh embodiment.

Fig. 14 is a graph showing the evaluation results of Examples 1 to 5 and Comparative Example 1.

Fig. 15 is a graph showing the evaluation results of Examples 6, 7 and Comparative Example 2.

Fig. 16 is a graph showing the evaluation results of Examples 8, 9 and Comparative Example 3.

Fig. 17 is a graph showing the evaluation results of Examples 10 and 11.

12‧‧‧Light reflection point

A‧‧‧Imaginary area

B‧‧‧Small area

g‧‧‧Imaginary lattice

X‧‧‧1st direction

Y‧‧‧2nd direction

Claims (18)

A light guide plate comprising a light guide plate substrate that propagates light, and includes a plurality of light reflection points formed on at least one surface of the light guide plate substrate; and a dot formation surface that is formed on a surface on which the plurality of light reflection points are formed Each of a plurality of imaginary regions obtained by dividing into a plurality of imaginary intervals is regularly arranged two-dimensionally with a plurality of imaginary lattices as printing targets; and a plurality of imaginary lattices of the plurality of imaginary lattices arranged two-dimensionally The light reflection point is formed, and the plurality of light reflection points are arranged in at least one of the plurality of imaginary regions in an arrangement of the light reflection points in the imaginary region selected from the plurality of imaginary regions A light distribution pattern in which the light reflection points in the imaginary region are arranged in translational symmetry is formed on the dot formation surface. The light guide plate of claim 1, wherein the arrangement of the light reflection points in the selected one of the imaginary regions and the imaginary of six or more of the 24 imaginary regions surrounding the selected one of the imaginary regions The configuration of the above-mentioned light reflection points in the region is translational symmetry. The light guide plate of claim 1 or 2, wherein the arrangement of the light reflection points in the selected one of the imaginary regions is four out of eight imaginary regions adjacent to the selected one of the imaginary regions The arrangement of the light reflection points in the above imaginary area is translational symmetry. The light guide plate of any one of claims 1 to 3, In each of the plurality of imaginary regions, a maximum diameter among a plurality of diameters of the plurality of light reflection points formed in the imaginary region is represented as D (μm), and the first alignment in the two-dimensional array The number of the virtual grids in the direction is expressed as L1 (number), and when the number of the virtual grids in the second array direction intersecting the first array direction in the two-dimensional array is expressed as L2 (number), 10 μm< D≦300 μm, 2<L1≦200 and 2<L2≦200. The light guide plate according to any one of claims 1 to 4, wherein, in each of the plurality of imaginary regions, the imaginary region is divided into a plurality of small regions, and the small region is an area in which the imaginary region is The number of the light reflection points in the inside is represented by n (n>1), and the number of the virtual grids in the first array direction in the two-dimensional array is expressed as L1 (number), and the two-dimensional array is The number of the virtual grids in the second array direction intersecting with the first array direction is expressed as L2 (number), and the set including the common number of L1 and L2 is represented as N1 and N2, respectively, and the above-described N1 and the above are formed. The elements of N2 are denoted as N1e and N2e, respectively, X is defined as N1e×N2e-n, Y is defined as N1e+N2e, and under the condition that X is 0 or more, N1e and N2e indicating that X and Y are the smallest are represented. For N1e _min and N2e _min , the number of the virtual grids in the first array direction of the small area is expressed as M1 (number), and the number of the virtual grids in the second array direction of the small area is represented as M2 ( When M1 is L1/N1e _min , the above M2 is L 2/N2e _min ; in each of the plurality of imaginary regions, the ratio of the small region in which the light reflection point is not formed is 75% or less. The light guide plate according to any one of claims 1 to 5, wherein the plurality of light reflection points formed on the dot formation surface include two or more of the light reflection points having different sizes. A design method of a light distribution pattern for a light guide plate, comprising: a design method of a light distribution pattern formed on a plurality of light reflection points on at least one side of a light guide plate substrate, and comprising: a coverage ratio setting step, which is attached to the light guide plate a dot forming surface which is a surface on which the light reflection point is formed, is divided into a plurality of regions at equal intervals, and a coverage ratio is set for each of the virtual regions; and a virtual lattice setting step is performed for each of the above The virtual area is set as a virtual grid to be printed, that is, the above-described virtual grid which is regularly arranged two-dimensionally; and the light reflection point condition setting step is for each of the above-mentioned virtual regions. Setting a size of the light reflection point formed on the virtual grid and the number of the light reflection points based on the coverage ratio; and a light reflection point arrangement step of selecting one of the plurality of virtual regions selected from the plurality of virtual regions The arrangement of the light reflection points in the region and the arrangement of the light reflection points in at least one of the plurality of imaginary regions remaining in the plurality of imaginary regions are translationally symmetrical, and in each of the imaginary regions The light reflection point is disposed on the virtual lattice to obtain the light distribution pattern. The method for designing a light distribution pattern for a light guide plate according to claim 7, wherein in the light reflection point arrangement step, the light reflection point in the selected one of the imaginary regions is arranged and surrounding the selected one The arrangement of the light reflection points in the imaginary regions of the six or more of the 24 imaginary regions in the imaginary region is a translational symmetry, and the light reflection dots are arranged on the imaginary lattice. The method for designing a light distribution pattern for a light guide plate according to claim 7 or 8, wherein in the light reflection point arrangement step, the light reflection point in the selected one of the imaginary regions is arranged and selected as described above The arrangement of the light reflection points in the imaginary regions of four or more of the eight imaginary regions adjacent to the imaginary region is a translational symmetry, and the light reflection dots are arranged on the imaginary lattice. The method for designing a light distribution pattern for a light guide plate according to claim 8, wherein after the imaginary lattice setting step, the imaginary region dividing step of dividing the imaginary region into a small region in each of the plurality of imaginary regions is further included; The small area is a region in which the number of the light reflection points in the virtual region is represented as n (n>1), and the number of the virtual lattices in the first array direction in the two-dimensional array is represented In the case of L1 (number), the number of the virtual grids in the second array direction intersecting with the first array direction in the two-dimensional array is expressed as L2 (number), and the set of the common numbers including the above L1 and the above L2 is included. The elements N1 and N2 are respectively denoted as N1e and N2e, X is defined as N1e×N2e-n, Y is defined as N1e+N2e, and X is 0 or more. In the above, X1 and N are the smallest, and N1e and N2e are represented as N1e _min and N2e _min , and the number of the virtual grids in the first array direction of the small area is expressed as M1 (number), and the small area is The second arrangement direction When the number of imaginary lattices is expressed as M2 (number), the above M1 is L1/N1e _min , and the above M2 is L2/N2e _min . The method of designing a light distribution pattern for a light guide plate according to any one of claims 7 to 9, wherein in the light reflection point arrangement step, the small area in which the light reflection point is not formed in each of the imaginary regions is The ratio is 75% or less, the light reflection point is placed on the virtual lattice. The method of designing a light distribution pattern for a light guide plate according to any one of claims 7 to 11, wherein in the light reflection point condition setting step, the size of the light reflection point is set to two or more; In the above-described step of arranging the virtual grid, two or more kinds of the light reflection points having different sizes are arranged. A light guide plate comprising a light distribution pattern designed by the design method of any one of claims 7 to 12. A method for manufacturing a light guide plate, which is a method for manufacturing a light guide plate having a plurality of light reflection points formed on at least one surface of a light guide plate substrate by using a printing device, wherein the printing device includes a plurality of or more arranged for printing a unit for printing a portion, and arranging the unit along an arrangement direction of the printing portion, the method for manufacturing the light guide plate comprising: a light distribution pattern designing step, which is designed by the design method according to any one of claims 7 to 12 a light distribution pattern of the light reflection point; and a light reflection point printing step of moving the unit relative to the light guide plate substrate while the printing portion of the unit is used on the light guide plate substrate The light distribution pattern prints the light reflection point. The method of manufacturing a light guide plate according to claim 14, wherein the printing portion is a nozzle; the unit is an ink jet head in which a plurality of nozzles are arranged; and the light reflecting point is an ultraviolet curable inkjet ink for a light guide plate. A light guide plate manufactured by the method of manufacturing a light guide plate according to claim 14 or 15. An edge illumination type surface light source device comprising: a light guide plate according to any one of claims 1 to 6, claim item 13 and claim item 16; and a light source for supplying light to a side surface of the light guide plate. A transmissive image display device comprising: the surface light source device of claim 17; and a transmissive image display portion disposed to face the exit surface of the surface light source device.