TW201337361A - Light guide plate, surface light source device, transmission type image display device, and manufacturing method of light guide plate - Google Patents

Abstract

One embodiment of the light guide plate 1 in the present invention is to use a printing apparatus arranged with two or more inkjet heads (5a, 5b) at the arrangement direction of a plurality of nozzles 51; at least one side of a light guide plate substrate is formed with a light guide plate with a light distribution pattern including a plurality of light reflection points (12a, 12b), and adjacent inkjet heads (5a, 5b) are configured in such a way that part of the plurality of nozzles 51 are overlapped at the direction of intersecting the arrangement direction; in a region Ro of the light distribution pattern and the region formed therein by the overlapping portion of adjacent inkjet heads, there is a mixture of light reflection point 12a formed by the inkjet head 5a and light reflection point 12b formed by another inkjet head 5b.

Description

Light guide plate, surface light source device, transmissive image display device, and method of manufacturing light guide plate

The present invention relates to a light guide plate, a surface light source device, a transmissive image display device, 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 a method of the surface light source device, there is a direct light type in which a light source is provided on the back side of the light guide plate, and an edge light method in which a light source is provided 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), and light of an angular component above the critical angle is emitted from the exit surface of the light guide plate, thereby supplying planar light. In order to make the luminance of the light-emitting surface uniform, gradation is performed in the light guide plates described in Patent Documents 1 and 2, and the gray scale causes the density of the light distribution pattern to become dense and dense as it separates from the light source.

Further, Patent Document 1 discloses a method of forming a dot-like light distribution pattern by droplet discharge (for example, inkjet printing). For example, in the inkjet printing method, there are cases where the inkjet head is printed in plural arrays in order to shorten the printing interval.

Patent Document 1: Japanese Patent Laid-Open Publication No. 2004-240294

Patent Document 2: Japanese Patent Laid-Open Publication No. 2008-27609

However, when the ink jet head is arranged in plural numbers and printed, linear brightness unevenness (streak unevenness) occurs in the connection portion between the ink jet heads due to the mounting accuracy and the position adjustment accuracy. In this regard, if the position of the ink jet head is to be adjusted with higher precision, a large amount of time and labor are required.

Accordingly, 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 method of manufacturing a light guide plate which are capable of reducing linear brightness unevenness of a connection portion between inkjet heads.

As a result of intensive research, the inventors of the present invention found that adjacent inkjet heads are arranged in such a manner that one of the nozzles is partially overlapped, and light formed by an inkjet head is mixed in a region of the light distribution pattern formed by the overlapping portions. The reflection point and the light reflection point formed by the other ink-jet head can reduce the linear brightness unevenness of the joint portion of the ink-jet heads with each other. The reason for this is that it is possible to prevent a portion where the distance between the light reflection points becomes larger or a smaller portion due to the mounting accuracy and the position adjustment accuracy of the ink jet heads, and the narrow portion is arranged in a narrow range in the scanning direction of the ink jet head. .

Therefore, in the light guide plate of the present invention, a light distribution pattern including a plurality of light reflection points is formed on at least one surface of the light guide plate substrate by using a printing device, and the printing device includes two or more ink jet heads in which a plurality of nozzles are arranged. And the inkjet head is arranged in a direction in which the plurality of nozzles are arranged; and the adjacent inkjet heads in the printing device are arranged such that one of the plurality of nozzles overlaps in a direction intersecting the arrangement direction, in the light distribution pattern In the region formed by the overlapping portion of the adjacent ink-jet heads, a light reflection point formed by one ink-jet head and a light reflection point formed by the other ink-jet head are mixed.

Moreover, the method of manufacturing a light guide plate of the present invention is a method of manufacturing a light guide plate in which a light distribution pattern including a plurality of light reflection points is formed on at least one surface of a light guide plate substrate by using a printing device, and the printing device has two or more arrangements. An ink jet head having a plurality of nozzles, and the ink jet head is arranged in a direction in which a plurality of nozzles are arranged; and an adjacent ink jet head in the printing apparatus Arranging in a manner that one of the plurality of nozzles overlaps in a direction crossing the alignment direction, and is mixed in the region in the light distribution pattern and formed by the overlapping portion of the adjacent inkjet heads by an inkjet A light distribution pattern is printed on the light guide plate substrate in such a manner that the light reflecting point formed by the head and the light reflecting point formed by the other ink jet head.

According to the method of manufacturing the light guide plate and the light guide plate, adjacent ink jet heads are arranged such that one of the nozzles partially overlaps, and light formed by one ink jet head is mixed in a region of the light distribution pattern formed by the overlapping portion The reflection point and the light reflection point formed by the other inkjet head, so that it is possible to prevent a portion where the distance between the light reflection points becomes larger or a smaller portion due to the mounting accuracy and the position adjustment accuracy of the inkjet heads. The scanning direction of the head is lined up in a narrow range. Therefore, it is possible to reduce linear brightness unevenness of the joint portion of the ink jet heads.

Preferably, the light reflection point of the region of the light distribution pattern is formed by ink ejected from a nozzle of either one of the ink jet heads. Thereby, it is possible to prevent confusion (deviation) in the shape or size of the light reflection point due to slight deviation of the nozzle positions of the two ink jet heads.

Further, in the region of the light distribution pattern, the light reflection point formed by one inkjet head and the light reflection point formed by the other inkjet head may be regularly arranged in a direction crossing the arrangement direction, or may be The arrangement direction is irregularly arranged in the direction in which the directions intersect. Therefore, there is no case where the distance between the light reflection points becomes larger or the smaller portion is aligned in the scanning direction of the inkjet head due to the mounting accuracy and the position adjustment accuracy of the inkjet heads, and thus it is possible to reduce the number of the inkjet heads in the scanning direction of the inkjet head. The linear brightness of the joint portion of the ink jet heads is not uniform.

The surface light source device of the present invention is an edge illumination type surface light source device, and includes the light guide plate and a light source that supplies light to a side surface of the light guide plate. According to the surface light source device, since the light guide plate is provided, unevenness in brightness of the edge illumination type surface light source device can be reduced.

A transmissive image display device according to the present invention includes the surface light source device and a transmissive image display unit that faces the emission of the surface light source device. According to the transmissive image Since the display device includes the surface light source device having the above-described light guide plate, it is possible to reduce unevenness in brightness of the transmissive image display device.

According to the present invention, it is possible to easily reduce the linear brightness unevenness of the joint portion of the ink jet heads. Further, it is possible to reduce the unevenness in brightness of the transmissive image display device using the edge illumination type having the light guide plate and the transmissive image display device using the edge illumination type surface light source device.

1‧‧‧Light guide plate

3‧‧‧Light source

5‧‧‧Inkjet head

5a‧‧‧Inkjet head

5b‧‧‧Inkjet head

5c‧‧‧Inkjet head

7‧‧‧UV lamp

9‧‧‧Inspection device

11‧‧‧Light guide plate substrate

12‧‧‧Light reflection point

12a‧‧‧Light reflection point

12b‧‧‧Light reflection point

13a‧‧‧Light reflection point

13b‧‧‧Light reflection point

20‧‧‧ surface light source device

30‧‧‧Transmission type image display unit

40‧‧‧Transportation agency

41‧‧‧Support Department

42‧‧‧Support Department

43‧‧‧Support Department

50‧‧‧Ink supply unit

51‧‧‧Nozzles

52‧‧‧Fixed parts

55‧‧‧ catheter

70‧‧‧ area

100‧‧‧Transmissive image display device

200‧‧‧ manufacturing equipment

A‧‧‧ moving direction

C‧‧‧ link section

Ro‧‧‧Overlapping area

S0‧‧‧ surface

S1‧‧‧ outgoing surface

S2‧‧‧Back

S3 ₁ ‧‧‧ end face

S3 ₂ ‧‧‧ end face

S3 ₃ ‧‧‧ end face

S3 ₄ ‧‧‧ end face

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 the light guide plate of the embodiment as seen from the back side.

Fig. 3 is a perspective view showing an embodiment of a method of manufacturing a light guide plate of the present invention.

4 is a schematic view showing a part of a method of manufacturing a light guide plate and a light distribution pattern of a prior light guide plate.

Fig. 5 is a view showing a part of the method of manufacturing the light guide plate of the embodiment and the light distribution pattern of the light guide plate of the embodiment.

Fig. 6 is a view showing a part of a light distribution plate of a modification of the present invention and a light distribution pattern of a light guide plate according to a modification of the present invention.

Fig. 7 is a view showing a part of a light guide plate of a modification of the present invention and a light distribution pattern of a light guide plate according to a modification of the present invention.

Fig. 8 is a view showing a part of a light distribution plate of a light guide plate according to a modification of the present invention and a light distribution pattern of a light guide plate according to a modification of the present invention.

Fig. 9 is a view showing a part of a light distribution plate of a light guide plate according to a modification of the present invention and a light distribution pattern of a light guide plate according to a modification of the present invention.

Fig. 10 is a schematic view showing a part of a light distribution plate of a light guide plate according to a modification of the present invention and a light distribution pattern of a light guide plate according to a modification of the present invention.

Figure 11 is a view showing a part of a light distribution pattern of a light guide plate according to a variation of the present invention; Figure.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or equivalent elements are denoted by the same symbols.

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 unit 30. The surface light source device 20 includes a light guide plate 1 having a light guide plate base material 11 and an edge illumination type surface light source device provided on the side of the light guide plate 1 and supplying the light source 3 to the light guide plate 1.

The light guide plate base material 11 has a substantially rectangular parallelepiped shape and has a rear surface S2 on the opposite side of the emission surface S1 and the emission surface S1, and four end surfaces S3 ₁ to S3 ₄ intersecting the emission surface S1 and the back surface S2. In the present embodiment, the four end faces S3 ₁ to S3 _{4 are} substantially orthogonal to the exit surface S1 and the back surface S2.

The light guide plate substrate 11 comprises a light transmissive material, preferably a polyalkyl (meth) acrylate resin sheet, a polystyrene sheet or a polycarbonate resin sheet, among which polymethacrylic acid is preferred. Methyl ester resin sheet (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 S2 of the light guide plate substrate 11 may be a surface on which the liquid repellent treatment is performed on substantially the entire surface of the back surface S2. The liquid-repellent treatment performed on the back surface S2 is a liquid-repellent treatment in such a manner that the contact angle when water droplets are dropped onto the back surface S2 is 80 to 130 degrees, and it is preferable that the contact angle is 85 to 120 degrees, more preferably The contact angle is a liquid treatment of 90 degrees to 110 degrees. In the present embodiment, the contact angle means a static 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, for example, 20 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. Fig. 2 is a plan view showing the light guide plate viewed from the back side. In Fig. 2, a light source 3 is also shown for convenience of explanation. As shown in FIG. 2, the light reflection point 12 becomes 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 point 12 is formed as a lattice point which is regularly two-dimensionally arranged over the entire back surface S2. Therefore, the coverage of the light reflection point 12 becomes lower toward the light incident portion side of the light source 3, and becomes higher as it goes away from the light source 3. It is preferable that the light reflection points 12 are not connected to each other, but actually there are cases where they are connected. In FIG. 2, the size and number of the light reflection points 12 are changed for convenience of explanation. As described below, the number of light reflection points 12 and the arrangement pattern are uniformly emitted from the exit surface S1 with uniform planar light. The way to adjust.

The light source 3 is disposed on the side opposite to the pair of end 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 two sides of the four sides of the back surface S2 of the rectangular shape, which constitutes the light-transmitting resin sheet 11, for example. In order to obtain a natural tone of light, it is particularly advantageous to combine the light reflecting dots 12 formed by the inkjet ink described below with the LEDs.

As shown in FIG. 1, the transmissive image display unit 30 is disposed opposite to the light guide plate 1 on the exit surface S1 side of the light guide plate 1. The transmissive image display unit 30 is, for example, a liquid crystal display unit having a liquid crystal cell.

In the above configuration, the light output from the light source 3 enters the light guide plate substrate 11 from the end faces S3 ₁ and S3 ₂ . The light incident on the light guide substrate 11 is mainly emitted from the exit surface S1 by diffuse reflection at the light reflection point 12. The light emitted from the exit surface S1 is supplied to the transmissive image display unit 30. The number of light reflection dots 12 and the arrangement pattern are adjusted such that uniform planar light can be efficiently emitted from the exit surface S1.

Next, a method of manufacturing the light guide plate 1 will be described.

The manufacturing apparatus 200 of the light guide plate 1 shown in FIG. 3 includes a conveyance mechanism 40 that conveys the light guide plate substrate 11, an inkjet head 5, and a UV (Ultraviolet) lamp 7. Can also be set as needed The inspection device 9 is placed. The ink jet head 5, the UV lamp 7, and the inspection device 9 are arranged in order from the upstream side in the moving direction A of the light guide plate substrate 11.

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

On the surface S0 of the light guide substrate 11 , a droplet-shaped inkjet ink pattern is printed in a dot shape by the ink jet head 5 supported by the support portion 41. At this time, the pattern printing is performed in such a manner that the ink droplets of the droplets dropped to the surface S0 are separated from each other.

The ink jet head 5 includes a plurality of nozzles of one line or more, and the nozzles are entirely in the width direction (direction perpendicular to A) of the region where the light reflection point 12 of the surface S0 of the light guide plate substrate 11 is formed. The surface S0 (back surface S2) of the light guide plate substrate 11 is aligned and fixed. The liquid droplets ejected from the plurality of nozzles by the ink jet method are uniformly printed in the entire width direction of the light guide substrate 11 at the same time. Preferably, the ink is printed while continuously moving the light guide plate substrate 11 at a constant speed. Alternatively, the ink may be printed in a state where the light guide plate substrate 11 is stopped, and the light guide plate substrate 11 may be moved to the next printing position, and then stopped, and the ink may be efficiently printed in a pattern including a plurality of dots.

The moving speed of the light guide plate substrate 11 is adjusted in such a manner that the ink can be appropriately printed. In the case of this embodiment, as shown in FIGS. 3 to 5, the ink jet head 5 includes a plurality of ink jet heads 5a to 5c each having a plurality of nozzles 51. The plurality of inkjet heads 5a to 5c are arranged in a direction orthogonal to the direction A of the conveyance of the light guide plate substrate 11, and are connected via the fixing member 52 so as to overlap each other at the end portions in the conveyance direction A. Further, in order to clarify the features of the present invention, only the adjacent ink jet heads 5a, 5b are shown in Figs. 4 and 5.

In the case of the present embodiment, the ink can be uniformly printed over 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. thus, The productivity of the light guide plate 1 is 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, when the large-sized 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 is produced, the effect of improving the productivity by the method of the present embodiment is large. 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 is transmitted from the exit surface S1 side, but this can be prevented by making the light reflection point 12 small.

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 cartridge that contains ink and a pump that sends ink. A plurality of conduits 55 can be coupled to a single ink cartridge or to a plurality of ink cartridges.

In order to form the light reflection point 12, the inkjet ink used for inkjet printing may be an ultraviolet curable ink containing a pigment, a photopolymerizable component, and a photopolymerization initiator, and 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 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 oxide particles is preferably from 50 to 3,000 nm, more preferably from 100 to 1,500 nm, and still more preferably from 150 to 600 nm. The calcium carbonate particles, the barium sulfate particles, and the titanium oxide particles having a cumulative 50% particle diameter D50 in the range of 50 to 3000 nm can be obtained by appropriately selecting according to the particle size distribution from a commercial product. The content ratio of the pigment to the ink is usually about 0.5 to 15.0% by mass based on the total mass of the ink. An ink using an inorganic material using an ink of at least one of calcium carbonate particles, barium sulfate particles, and titanium dioxide particles. When considering the storage stability of the inorganic ink, that is, the inorganic pigment precipitation property, it is more preferable to use the calcium carbonate particles having the smallest specific gravity among the three 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 8.0~12.0 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 (meth)acrylic aliphatic urethane. When the weight average molecular weight and the content ratio of the (meth)acrylic aliphatic 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 or a fluorine-based ink to the 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 containing the hardened ink is formed.

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. Alternatively, the light guide plate may be continuously inspected by an inspection device provided on the downstream side of the ink jet head as in the present embodiment, and the light guide plate may be inspected offline by a separately prepared inspection device. Alternatively, the inspection of the light guide plate by the inspection device may be omitted.

Generally, the printing pattern of the ink which should be the light reflecting point 12 is designed such that the uniform planar light can be efficiently emitted from the exit surface S1 as desired. In this case, since the arrangement pattern of the plurality of light reflection points 12 is substantially the desired pattern, the light supplied from the light source 3 to the light-transmitting resin sheet 11 can be efficiently extracted from the light exit surface S1. As a result, light can be emitted from the light exit surface S1 of the light guide plate 1 with higher brightness. Moreover, since the arrangement pattern of the light reflection points 12 is a desired pattern as described above, it is possible to emit light substantially uniformly from the light exit surface S1.

Since the surface light source device 20 is provided with the light guide plate 1, it is possible to emit light with higher brightness. Further, since the transmissive image display device 100 is illuminated by light having a higher luminance emitted from the surface light source device 20, it is possible to display an image having a better display quality with a clearer contrast.

Here, as shown in FIG. 4, when the inkjet heads 5a and 5b are arranged in plural numbers and printed, In the connection portion C between the inkjet heads 5a and 5b, the linear brightness unevenness (streak unevenness) occurs due to the mounting accuracy and the positional adjustment accuracy.

Therefore, in the present embodiment, as shown in Fig. 5, the adjacent ink-jet heads 5a and 5b are partially disposed in the transport direction A (the scanning direction and the direction intersecting the nozzle arrangement direction) in one of the plurality of nozzles 51. Coincident configuration. Further, the light distribution pattern is printed such that the light reflection point 12a formed by the ink jet head 5a and the light reflection point 12b formed by the ink jet head 5b are mixed in the overlapping region Ro of the light distribution pattern formed by the overlapping portions.

Specifically, in the overlapping area Ro of the light distribution pattern, the line of the light reflection point 12a along the conveyance direction A and the line of the light reflection point 12b are alternately arranged in the direction intersecting the conveyance direction A (the arrangement direction of the nozzles). The pattern is printed in a manner. In other words, in the present embodiment, the light reflection points 12a and 12b are regularly arranged in the transport direction A in the overlapping area Ro of the light distribution pattern. Furthermore, the row of the light reflecting point 12a and the row of the light reflecting point 12b may be alternately arranged for each row as shown in FIG. 5, or may be alternately arranged in plural units.

As described above, according to the method of manufacturing the light guide plate 1 and the light guide plate 1 of the present embodiment, as shown in FIG. 5, the adjacent ink jet heads 5a and 5b are partially in the transport direction A (the direction in which the nozzles are arranged). The direction of the intersection is arranged in a superimposed manner, and the light reflection point 12a formed by one inkjet head 5a and the light reflection formed by the other inkjet head 5b are mixed in the overlapping area Ro of the light distribution pattern formed by the overlapping portion. With the point 12b, it is possible to prevent the portion where the distance between the light reflection points 12a and 12b is increased or the smaller portion in the conveyance direction A due to the mounting accuracy and the position adjustment accuracy of the inkjet heads 5a and 5b (the inkjet head 5a, The scanning direction of 5b is arranged in a row. Therefore, the linear brightness unevenness of the connection portion C between the inkjet heads 5a and 5b can be reduced.

However, if the light reflection point in the overlap region Ro of the light distribution pattern is formed by the ink ejected from the nozzles of the adjacent ink jet heads 5a, 5b, there is a mounting accuracy and position adjustment due to the ink jet head. Accuracy makes the size of the light reflection point larger or deforms the shape of the light reflection point. However, according to the embodiment, in the overlapping area Ro of the light distribution pattern The light reflection point is formed by the ink ejected from the nozzle of either one of the ink jet head 5a and the other ink jet head 5b, so that it is possible to prevent a slight deviation of the nozzle positions of the two ink jet heads 5a, 5b. The light reflects the shape (or deviation) of the shape or size of the dots.

Further, the present invention is not limited to the above-described embodiment and can be variously modified. For example, in the present embodiment, the overlapping area Ro of the light distribution pattern is alternately arranged in the direction in which the light reflection point 12a along the conveyance direction A and the light reflection point 12a intersect in the direction of the conveyance direction A. In the manner of printing the light distribution pattern, as shown in FIG. 6, in the overlapping area Ro of the light distribution pattern, the light reflection point 12a and the light reflection point 12b in the direction intersecting the conveyance direction A The light distribution pattern is printed so as to be alternately arranged in the transport direction A. In this modification, also in the overlap region Ro of the light distribution pattern, the light reflection points 12a and 12b are regularly arranged in the conveyance direction A. Further, the row of the light reflecting point 12a and the row of the light reflecting point 12b may be alternately arranged in each row as shown in FIG. 6, or may be alternately arranged in a plurality of rows.

Further, as shown in FIG. 7, in the overlapping region Ro of the light distribution pattern, the light reflection point 12a and the light reflection point 12b are alternately arranged in the conveyance direction A, and also in the direction intersecting the conveyance direction A. The light distribution pattern is printed in an alternately arranged manner. In this modification, also in the overlap region Ro of the light distribution pattern, the light reflection points 12a and 12b are regularly arranged in the conveyance direction A. Further, the light reflection point 12a and the light reflection point 12b may be alternately arranged as shown in FIG. 7, or may be alternately arranged in plural units.

Further, as shown in FIG. 8, in the overlapping region Ro of the light distribution pattern, the light reflection point 12a and the light reflection point 12b are irregularly arranged in the conveyance direction A, and also intersect with the conveyance direction A. The light distribution pattern is printed in a manner that is irregularly arranged in the direction.

Further, as shown in FIG. 9, in the overlapping region Ro of the light distribution pattern, the light reflection point 12a and the light reflection point 12b are regularly arranged in the conveyance direction A, and also in the direction intersecting the conveyance direction A. The light distribution pattern is printed in a regularly arranged manner.

Further, in the above-described embodiment and modifications, the ink jet head 5a is formed in the same manner. The light reflecting point 12a and the ink jet head 5b form the same light reflecting point 12b, but the ink jet head 5a may be formed with different light reflecting points 12a, 13a as shown in Fig. 10 and the ink jet head 5b is formed differently. The features of the present invention are applied in the form of light reflecting points 12b, 13b. For example, in FIG. 10, the ink jet head 5a alternately forms the line of the light reflection point 12a in the conveyance direction A and the line of the light reflection point 13a in the direction crossing the conveyance direction A, and similarly, the inkjet head 5b. The line of the light reflection point 12b in the conveyance direction A and the line of the light reflection point 13b are alternately formed in a direction crossing the conveyance direction A. In this case, the light reflection point 12a, the light reflection point 13a, the light reflection point 12b, and the light reflection point 13b may be regularly (or irregularly) arranged in the transport direction A in the overlap region Ro of the light distribution pattern. And the light distribution pattern is printed in a regular (or irregularly) arrangement in a direction crossing the transport direction A. This method can also be achieved by arranging the ink jet heads in two or more rows or by using an ink jet head having two or more nozzle rows.

Further, in the above-described embodiments and modifications, a light distribution pattern formed of light reflection points 12a and 12b (and 13a and 13b) having one size is exemplified, but it may have 2 as shown in FIG. Light reflection points of various sizes are arranged in an irregular order, and light reflection points having three or more sizes may be arranged in an irregular order.

As described above, when light reflection points having two or more sizes are arranged in an irregular order, the gray scale change caused by the light reflection point can be reduced. As a result, unevenness in luminance can be reduced in a region where the coverage of the light distribution pattern is low as close to the light incident portion side of the light source. In particular, it is effective to form a region in which a contrast ratio of 50% or less is formed by a plurality of light reflection points.

Further, in the present embodiment, the case where the light source 3 is disposed on each of the side faces S3 ₁ and S3 ₂ facing each other is exemplified. However, the light source 3 may be disposed on the side of at least one end surface that intersects the light exit surface S1 (or the back surface S2) of the light-transmitting resin sheet 11.

[Examples]

The light guide plate 1 according to the embodiment of the present invention was experimentally produced as an example, and a comparative example The light guide plate was compared and evaluated. The light guide plates of the examples and comparative examples are as follows.

(Example 1)

A PMMA resin sheet of 600 mm × 345 mm was prepared as a translucent resin sheet, and a light-shielding plate was produced using an ultraviolet curable inkjet ink containing no pigment.

Specifically, the mask film is peeled off from the PMMA resin sheet, and the light distribution pattern shown in FIG. 5 is ink-jet-printed on the peeled surface by the ultraviolet curable inkjet ink. As the ink jet head, an ink jet head having a nozzle-to-nozzle distance of about 84.5 μm was used. Further, the mounting accuracy and the position adjustment accuracy when a plurality of the ink jet heads are arranged and connected are about 15 μm. Second, the printed inkjet ink is irradiated with ultraviolet light to harden the ink. Specifically, after the ultraviolet curable inkjet ink pattern was printed on the PMMA resin sheet, the ink was light-cured by irradiating ultraviolet rays after 6 seconds. As a result, the light guide plate of Example 1 in which a uniform light distribution pattern having a coverage ratio of 48% was formed was obtained.

(Example 2)

The light guide plate of Example 2 was obtained in the same manner as in Example 1 except that the light distribution pattern shown in Fig. 6 was formed.

(Example 3)

The light guide plate of Example 3 was obtained in the same manner as in Example 1 except that the light distribution pattern shown in Fig. 7 was formed.

(Example 4)

The light guide plate of Example 4 was obtained in the same manner as in Example 1 except that the light distribution pattern shown in Fig. 8 was formed.

(Example 5)

The light guide plate of Example 5 was obtained in the same manner as in Example 1 except that the light distribution pattern shown in Fig. 9 was formed.

(Example 6)

The light guide plate of Example 6 was obtained in the same manner as in Example 1 except that the light distribution pattern shown in Fig. 10 was formed.

(Comparative Example 1)

The light guide plate of Comparative Example 1 was obtained in the same manner as in Example 1 except that the light distribution pattern shown in FIG. 4 was formed.

In the present evaluation, in the television unit using the LED as the light source, the diffusion film, the ruthenium film, the DBEF (Dual Brightness Enhancement Film), and the embodiment 1 to 6 instead of the light guide plate are respectively incorporated. And the light guide plate of Comparative Example 1. Further, the television units are illuminated to visually evaluate the unevenness of the stripes (the linear brightness is not uniform) (the film of the diffusion film, the ruthenium film, and the DBEF is not present). Further, it was also visually evaluated that unevenness (film) was used when a diffusion film was used. The evaluation results of these are shown in Table 1.

According to the evaluation result, it is known that adjacent inkjet heads are partially overlapped by one of the nozzles, and in the overlapping region of the light distribution pattern formed by the overlapping portions, the light reflection point formed by one inkjet head is mixed and The light reflection point formed by the other ink jet head can reduce the unevenness of the streaks of the ink jet heads (the linear brightness unevenness).

5‧‧‧Inkjet head

5a‧‧‧Inkjet head

5b‧‧‧Inkjet head

12a‧‧‧Light reflection point

12b‧‧‧Light reflection point

51‧‧‧Nozzles

A‧‧‧ moving direction

C‧‧‧ link section

Ro‧‧‧Overlapping area

Claims (8)

A light guide plate in which a light distribution pattern including a plurality of light reflection points is formed on at least one surface of a light guide plate substrate by using a printing device, and the printing device includes two or more ink jet heads in which a plurality of nozzles are arranged, and The inkjet head is arranged in an arrangement direction of the plurality of nozzles; and an adjacent inkjet head of the printing device is disposed such that one of the plurality of nozzles overlaps in a direction crossing the arrangement direction; In the region of the light distribution pattern and formed by the overlapping portions of the adjacent ink jet heads, a light reflection point formed by one ink jet head and a light reflection point formed by the other ink jet head are mixed. The light guide plate of claim 1, wherein the light reflection point of the region in the light distribution pattern is formed by ink ejected from a nozzle of any one of the one and the other ink jet heads. The light guide plate of claim 1 or 2, wherein in the above region in the light distribution pattern, a light reflection point formed by one inkjet head and a light reflection point formed by the other inkjet head are intersected in the alignment direction Regularly configured in the direction. The light guide plate of claim 1 or 2, wherein in the above region in the light distribution pattern, a light reflection point formed by one inkjet head and a light reflection point formed by the other inkjet head are intersected in the alignment direction Irregularly configured in the direction. A method for manufacturing a light guide plate, which is a method for 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 by using a printing device, wherein the printing device has two or more arrays An ink jet head of a plurality of nozzles, wherein the ink jet head is arranged in an arrangement direction of the plurality of nozzles; and an adjacent one of the plurality of nozzles in the printing apparatus is partially intersected with the array direction Aligned in the direction of the direction; In the region where the region of the light distribution pattern is formed by the overlapping portion of the adjacent inkjet heads, a light reflection point formed by one inkjet head and a light reflection point formed by the other inkjet head are mixed. In one embodiment, the light distribution pattern is printed on the light guide plate substrate. A light guide plate manufactured by the method of manufacturing a light guide plate according to claim 5. An edge illumination type surface light source device comprising: the light guide plate of claim 1; and a light source that supplies light to a side of the light guide plate. A transmissive image display device comprising: the surface light source device of claim 7; and a transmissive image display portion disposed to face the emission of the surface light source device.