JP2004102106A - Press forming apparatus and press forming method for light diffusion plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a light diffusion plate which is formed with fine rugged patterns as planned relating to press forming of the light diffusion plate disposed in parallel with a liquid crystal plate of a liquid crystal unit between the liquid crystal plate and a light source section and which can emit incident light from the light source section to the liquid crystal plate without unevenness. <P>SOLUTION: The light diffusion plate A consisting of a thermoplastic resin is disposed parallel with the liquid crystal plate 102 between the liquid crystal plate 102 and the light source section, diffuses the light of the light source section made incident from the incident surface A1 and emits the light from an exit surface A2 toward the liquid crystal plate 102. The above light diffusion plate is formed by heating and cooling the thermoplastic resin to its thermal deformation temperature or above while pressurizing the resin between a first die 3 which can form rugged patterns A5 restricted in the incidence of the light from the light source section as compared with another portions A4 in the vicinity around a portion A3 facing the light source section on the incident surface A1 and a second die 6 facing this die. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a press-forming apparatus and a press-forming method for a light diffusion plate provided between a liquid crystal plate of a liquid crystal unit and a light source unit in parallel to the liquid crystal plate.
[0002]
[Prior art]
In recent years, with the adoption of large-sized liquid crystal units in liquid crystal televisions and the like, liquid crystal units have been replaced with light guide plates that emit light from a light source unit on the side surface of the liquid crystal unit to the liquid crystal plate. Increasingly, a light diffusion plate that emits light from a light source unit on the back surface to a liquid crystal plate is used. In the method of manufacturing the light diffusion plate, various techniques are disclosed for uniformly emitting light incident from the light source unit to the liquid crystal plate without unevenness.
[0003]
For example, in Japanese Patent Application Laid-Open No. Hei 4-301351 (Patent Document 1), a light semi-transmissive film is formed on a light diffusion plate by printing, and the light semi-transmissive film is formed so as to gradually decrease as the distance from the light source increases. Is described. However, the method of printing on the light diffusing plate requires a drying step after printing, which complicates the process, and makes it difficult to adjust minute dots in screen printing, so that the boundary between the printing part and the part other than the printing part is difficult. And the problem that light unevenness appears on the surface of the liquid crystal plate.
In addition to the method of printing on a light diffusion plate, Japanese Patent Application Laid-Open No. 9-304623 (Patent Document 2) describes that a light diffusion plate having a groove on an exit surface or an entrance surface is formed by injection molding. I have. However, when molding a light diffusion plate by injection molding, there are problems such as poor flow of the molten resin in the cavity and parallelism of the mold of the mold clamping device. It was difficult to obtain a light diffusion plate having a uniform thickness and no warpage.
[0004]
As a solution to the above problem, Japanese Patent Application Laid-Open No. H10-282315 (Patent Document 3) describes that a concavo-convex pattern provided on an incident surface or the like of a light diffusion plate is formed by hot pressing. However, since the publication does not have a function of changing the temperature of the pressurizing mold during one molding cycle, the fine uneven pattern formed on the surface of the light diffusion plate by pressurization at the time of mold release is broken, and as intended. It was difficult to form a fine uneven pattern. Further, the above publication does not specifically disclose what manufacturing apparatus is used, under what molding conditions, and at what position on the light diffusion plate is provided with the concavo-convex pattern.
[0005]
[Patent Document 1]
Japanese Patent Application Laid-Open No. Hei 4-301351 (Claim 1, FIG. 1)
[0006]
[Patent Document 2]
JP-A-9-304623 ((0030), FIG. 1)
[0007]
[Patent Document 3]
JP-A-10-282315 ((0039), FIG. 3)
[0008]
[Problems to be solved by the invention]
The present invention has been made in view of the above-described problem, and a fine concave-convex pattern is intended for press-forming a light diffusion plate provided between a liquid crystal plate of a liquid crystal unit and a light source unit in parallel to the liquid crystal plate. It is an object of the present invention to obtain a light diffusion plate that can be formed as described above and that can emit light incident from a light source unit to a liquid crystal plate without unevenness. It is another object of the present invention to form a thin light diffusion plate having a large area which is difficult to be formed by injection molding, in particular, without unevenness of light emitted from the light diffusion plate and warpage of the light diffusion plate.
[0009]
[Means for Solving the Problems]
The apparatus for press-molding a light diffusing plate according to claim 1 is provided between the liquid crystal plate and the light source unit in parallel to the liquid crystal plate, and diffuses light from the light source unit incident from an incident surface to the light emitting unit from the exit surface. A light diffusing plate made of a thermoplastic resin that emits toward the liquid crystal plate is provided with a concavo-convex pattern that restricts the incidence of light from the light source unit from other portions in the vicinity of the part facing the light source unit on the incident surface. While forming the first mold and the second mold opposite to the first mold and heating the first mold and the second mold at a temperature equal to or higher than the thermal deformation temperature of the thermoplastic resin, It is characterized by pressure molding. Therefore, by performing heating and cooling while applying pressure, the molding time can be shortened, and the concavo-convex pattern formed when the light diffusion plate and the mold are released from the mold does not collapse.
[0010]
The press forming apparatus for a light diffusing plate according to claim 2 is the press forming apparatus according to claim 1, wherein the first mold has a light source portion near the center of a portion facing the light source portion on the incident surface and a light source portion other than the other portion. A first stamper capable of forming a fine concavo-convex pattern for restricting the incidence of light from the substrate. Therefore, a fine concavo-convex pattern can be freely formed on the stamper, and when the pattern is corrected or changed, only the stamper may be replaced without changing the entire mold.
[0011]
According to a third aspect of the present invention, there is provided the press-forming apparatus for a light diffusion plate according to the first or the second aspect, wherein the second mold has a fine uneven pattern substantially uniformly on an emission surface of the light diffusion plate to be molded. A second stamper capable of forming the second stamper is attached.
Therefore, a concavo-convex pattern can be simultaneously formed on both surfaces of the light diffusion plate to be formed.
[0012]
According to a fourth aspect of the present invention, there is provided a press forming apparatus for a light diffusion plate, wherein the heating means comprises a resistance heating plate provided to be separated from the cooling means. Therefore, heating and cooling of the stamper can be easily performed.
[0013]
According to a fifth aspect of the present invention, there is provided a method for press-molding a light diffusion plate using the light diffusion plate press-forming apparatus according to any one of the first to fourth aspects. It is characterized in that heating and cooling are performed while applying pressure to any one of a resin flat plate, a transparent polycarbonate resin flat plate, and a transparent cycloolefin resin flat plate.
Therefore, the manufacturing cost of the light diffusion plate can be reduced, and the light from the light source can be emitted to the liquid crystal plate without loss.
[0014]
According to a sixth aspect of the present invention, there is provided a method for press-molding a light diffusion plate, comprising the steps of: Alternatively, heating and cooling are performed while applying pressure to any of an acrylic resin flat plate, a polycarbonate resin flat plate, and a cycloolefin resin flat plate in which a pigment made of titanium oxide is mixed. Therefore, even if the concavo-convex pattern of the light diffusion plate is reduced, light unevenness does not occur.
[0015]
According to a seventh aspect of the present invention, there is provided a press-forming method for a light diffusion plate according to the fifth or sixth aspect, wherein the resin flat plate such as an acrylic resin has a substantially rectangular shape, and has a length in a diagonal direction with respect to a thickness. Is 200 to 400 times. Therefore, the thickness of the light diffusion plate used for a large liquid crystal television or the like can be reduced.
[0016]
The press-forming method for a light diffusion plate according to claim 8 uses the light-diffusion plate press-forming apparatus according to claim 1, in which the number of the light source units is previously determined in a portion of the incident surface that faces the light source unit. It is characterized in that heating and cooling are performed while applying pressure to any one of an acrylic resin flat plate, a polycarbonate resin flat plate, and a cycloolefin resin flat plate having a concave or convex portion corresponding to the above. Therefore, even if the concavo-convex pattern of the light diffusion plate is reduced, light unevenness does not occur.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a diagram showing a state where the light diffusing plate of the present invention is attached to a liquid crystal unit. FIG. 2 is a cross-sectional view of the light diffusion plate press-forming apparatus of the present invention. FIG. 3 is a diagram showing a concavo-convex pattern forming portion of the first stamper attached to the light diffusion plate press-forming apparatus of the present invention.
[0018]
As shown in FIG. 1, a substantially rectangular light diffusion plate A press-molded in the present invention is provided between a liquid crystal plate 102 of a liquid crystal unit 101 and a fluorescent tube 103 serving as a light source unit in parallel with the liquid crystal plate 102. Things. Then, the light incident on the incident surface A1 of the light diffusing plate A from the fluorescent tube 103 is diffused by the light diffusing plate A, and is emitted from the emitting surface A2 toward the liquid crystal plate 102 without unevenness of the light. Further, a prism sheet 104 may be provided between the light diffusing plate A and the liquid crystal plate 102 to further reduce unevenness of emitted light. The light diffusion plate A press-molded in this embodiment is used for a 21-inch liquid crystal television, and has a diagonal length of 580 mm and a thickness of 3 mm.
[0019]
As shown in FIG. 2, a press forming apparatus 1 for forming a light diffusing plate A according to the present invention includes a lower die 3 as a first die placed on a bed 2 and a pressing cylinder (not shown) as pressing means. There is provided an upper mold 6 which is a second mold attached to an upper movable platen 5 fixed to a ram 4 which is driven to move up and down. In the press molding apparatus 1, a first stamper 7 (details will be described later) is attached to the lower die 3, and a second stamper 8 (details will be described later) is attached to the upper die 6. Then, the first stamper 7 and the second stamper 8 press and heat the entrance surface A1 and the exit surface A2 of the substantially rectangular light diffusion plate A between the lower die 3 and the upper die 6, respectively. Transfer is performed, and press forming of the light diffusion plate A is performed. Note that the pressurizing means of the press forming apparatus 1 is not limited to the pressurizing cylinder, but may use a crank mechanism or a toggle mechanism driven by an electric motor, and use a combination of a servomotor and a ball screw. Pressurizing means may be used. Further, the press forming apparatus 1 may be one in which the lower die 3 as the first die is raised and lowered by the pressing means. Further, the light diffusion plate A which stands upright in the vertical direction may be press-formed by a first die and a second die provided on both sides.
[0020]
The lower mold 3 will be described. A flat cooling board 9 serving as a cooling means is attached to the lower mold 3. The cooling board 9 has a plurality of temperature control medium passages 10 formed therein, and the temperature is controlled to a predetermined temperature by flowing the temperature control medium from a temperature controller (not shown). A rubber sheet 12 which is an elastic body which is a first insulator capable of insulating between the cooling board 9 and a resistance heating plate 16 to be described later is stuck on the entire surface 11 of the cooling board 9 formed of a flat surface. I have.
[0021]
The cooling plate 9 is provided with concave portions 13 at a plurality of positions (four positions in this embodiment), and a hydraulic cylinder 14 serving as a separating means is attached to the concave portions 13 so that the rod 15 can protrude. A support portion 17 is fixed to the tip of the rod 15 of the hydraulic cylinder 14, and the support portion 17 is connected to a resistance heating plate 16 as a heating means via a rubber sheet 18 which is an insulator attached to the surface of the support portion 17. It is fixed to the back surface 23. A proximity switch (not shown) is attached to one side of the cooling board 9 so as to detect whether or not the resistance heating plate 16 and the cooling board 9 are in contact with each other via the rubber sheet 12.
[0022]
In this embodiment, the resistance heating plate 16 is a flat mirror plate made of a stainless steel plate having a thickness of 3 mm, a length of 550 mm in the longitudinal direction, and a width of 380 mm. Terminal portions 19a and 19b are provided at one end and the other end in the longitudinal direction of the resistance heating plate 16, respectively. The terminals 19a and 19b are provided with electric wires 20 and 20 from a DC power supply or an AC power supply (not shown). The resistance heating plate 16 is connected so as to be able to conduct electricity. In this embodiment, a current of 1.8 V and 4000 A is applied to the resistance heating plate 16 as a heating means. However, the present invention is not limited to this numerical value. The current value and the like may be reduced by using a resistance heating plate 16 having a small thickness.
[0023]
On the surface 21 of the resistance heating plate 16, a second insulating material capable of insulating the resistance heating plate 16 from the first stamper 7, which is a transfer plate for directly pressing the incident surface A1 of the substantially rectangular light diffusion plate A, is provided. A rubber sheet 22 as a body is provided. A temperature sensor 24 for measuring the temperature is attached to the resistance heating plate 16. Note that the heating means is not limited to the resistance heating plate 16, but may use a cartridge heater or a temperature control medium such as oil or steam. In these cases, a cartridge heater or a temperature control medium passage may be formed behind the concavo-convex pattern forming portion 7a or 7d in the first stamper 7, which will be described later, so that the temperature of that portion is higher than that of the other portions. Often, the cooling means of the corresponding part also has a high cooling capacity.
[0024]
On the surface 21 side of the resistance heating plate 16 to which the rubber sheet 22 as the second insulator is attached, a first stamper 7 as a flat transfer plate is attached.
Since the resistance heating plate 16 is flat, the first stamper 7 is provided so as to be easily replaceable according to the light diffusion plate A to be formed. The first stamper 7 is a nickel plate having a thickness of 0.1 mm to 1.0 mm on which the concave / convex pattern forming portions 7a or 7d are formed as shown in FIG. As shown in FIGS. 1 and 3, when the light diffusing plate A is mounted on the liquid crystal unit 101, the concave and convex pattern forming portion 7a of the first stamper 7 forms the fluorescent tube 103 as the light source portion on the incident surface A1. A portion of the uneven pattern A5 that restricts the incidence of light from the fluorescent tube 103 as compared with the other portion A4 is formed in the vicinity of the portion A3 opposite to the center. The band of the uneven pattern A5 of the light diffusion plate A is formed in the longitudinal direction at intervals of 30 mm to 40 mm according to the pitch of the fluorescent tubes 103 of the liquid crystal unit 101. In this embodiment, eight uneven patterns A5 are formed. Although bands are formed, the number and the like are not limited.
[0025]
As an example of the uneven pattern forming portion of the first stamper 7, as shown in FIG. 3A, the uneven pattern forming portion is provided only in the vicinity of a portion A3 of the light diffusing plate A facing the light source portion. 7a is formed, and an example in which a portion 7b without the concavo-convex pattern forming portion 7a is provided in a portion that presses against another portion A4 of the light diffusion plate A is illustrated.
The portion of the light diffusion plate A adjacent to the location of the fluorescent tube 103 at a predetermined distance can be formed so that the reflection of light from the fluorescent tube 103 is greater than that of the other portion A4.
[0026]
As another example of the concavo-convex pattern forming portion of the first stamper 7, a fine concavo-convex pattern forming portion 7c is formed on the entire surface of the stamper 7 (b) as shown in FIG. An example in which an uneven pattern forming portion 7d in which the density and / or the size of the uneven pattern is increased from the uneven pattern forming portion 7c in the vicinity of a portion A3 of the plate A facing the light source portion is exemplified. You. In both of the examples (a) and (b) of FIGS. 3A and 3B, the concave and convex pattern forming portion of the first stamper 7 is different only in the vicinity of the portion A3 facing the light source portion of the light diffusing plate A. It is desirable to reduce the density and / or size of the concavo-convex pattern in accordance with the distance between the light diffusion plate A and the fluorescent tube 103 instead of clearly distinguishing the portion from the above. Further, other than the illustration, a groove or a grain surface may be formed in the vicinity of the portion A3 of the light diffusion plate A facing the light source section as a center.
[0027]
Similarly to the lower mold 3, the upper mold 6 as the second mold has a flat cooling plate 9 whose temperature is controlled to a predetermined temperature, and a predetermined means during one molding cycle by a separating means from the cooling plate 9. A resistance heating plate 16 that can be separated at intervals and whose temperature is controlled at least at the time of separation, a rubber sheet 12 that is a first insulator that can insulate between the resistance heating plate 16 and the cooling plate 9, A rubber sheet 22 as a second insulator attached to the upper surface of the resistance heating plate 16 is provided. In this embodiment, a second stamper 8 is attached to the rubber sheet 22 of the upper die 6. The second stamper 8 is a stamper provided with a concavo-convex pattern forming portion over the entire surface and capable of transfer-molding a fine concavo-convex pattern almost uniformly on the emission surface A2 of the light diffusion plate A. However, the first stamper 7 may be attached to the upper die 6 as well. The upper die 6 may be provided with an uneven pattern forming portion by means other than the stamper 8. Further, in the press forming apparatus 1, the output surface A2 of the light diffusion plate A may not be processed.
Further, the first stamper 7 may be attached to the upper mold 6 as the first mold, and the second stamper 8 may be attached to the lower mold 3 as the second mold.
[0028]
In this embodiment, the press forming apparatus 1 includes the cylinders 27a and 27b provided between the bed 2 and the upper movable platen 5, and the lower space of the upper movable platen 5 fits the cylinders 27a and 27b to form the molding space 26. The molding space 26 is provided so as to be able to be isolated from the outside air, and the molding space 26 is capable of being depressurized by a vacuum pump (not shown).
However, press forming may be performed under atmospheric pressure without providing the press forming apparatus 1 with the cylinders 27a and 27b and the like.
[0029]
Next, a method of press-forming the light diffusing plate A of this embodiment will be described. In this embodiment, the substantially rectangular light diffusing plate A is press-formed from a transparent acrylic resin flat plate having no light diffusing material. Further, as the resin to be used, other thermoplastic resin plates such as a transparent polycarbonate resin flat plate and a transparent cycloolefin resin flat plate may be used. Further, a milk half plate in which fine particles of silicon resin or a pigment such as titanium oxide is mixed as a light diffusing material may be used for the resin flat plate. The resin flat plate for the light diffusing plate A is formed by extrusion molding or the like, and is cut by a cutting device such as a laser.
[0030]
As described above, in this embodiment, the size of the resin flat plate for the light diffusion plate A, which is press-molded, is for a 21-inch liquid crystal television and has a uniform thickness of 3 mm. The present invention mainly aims to press-mold a light diffusion plate A having a large area, and a resin flat plate for a light diffusion plate A having a uniform thickness of 4 mm for a 40-inch liquid crystal television. Press forming is also assumed. The resin flat plate for the light diffusion plate A, which is press-molded according to the present invention, has a length in a diagonal direction of 150 to 400 times the thickness. In the previous molding cycle, the upper mold 6 of the press molding apparatus 1 has been moved upward by the ram 4 which is moved up and down, and the resistance heating plate 16 attached to the lower mold 3 and the upper mold 6 is a separating means. It is at a position separated from the cooling boards 9, 9 by extension of the hydraulic cylinder 14. The cooling boards 9, 9 are controlled at 20 ° C. by water as a temperature control medium sent from a temperature controller (not shown).
[0031]
Then, a resin flat plate for the light diffusion plate A is placed on the first stamper 7 of the lower die 3 of the press forming apparatus 1. At this time, the resin flat plate for the light diffusion plate A is positioned at a regular pressing position by being guided by the frame 25. When it is detected by a not-shown photoelectric tube or the like whether or not the resin flat plate for the light diffusion plate A has been positioned at the normal pressing position, the molding space 26 is isolated from the outside air by the cylinders 27a and 27b, and is a decompression means not shown. The vacuum pump is turned on, and the pressure in the molding space 26 is reduced to 20 hPa. When a predetermined time elapses after the pressure in the molding space 26 is reduced by the vacuum pump, a pressurizing cylinder (not shown) is controlled, and the entire upper die 6 including the resistance heating plate 16 is lowered by the ram 4 so that the light diffusing plate A The second stamper 8 attached to the upper mold 6 is brought into close contact with the resin flat plate for use. At this time, the rod 15 of the hydraulic cylinder 14 is extended from the resin flat plate for the light diffusion plate A, and the resistance heating plate 16 and the cooling plate 9 are separated from each other. Is not done immediately.
[0032]
When the contact between the second stamper 8 and the resin flat plate for the light diffusing plate A is detected by a not-shown photoelectric tube or the like, the resistance heating plates 16 of the lower mold 3 and the upper mold 6 are energized, and the resistance heating is started. The temperature of the plate 16 is raised to 160 ° C. The temperature of the resistance heating plate 16 provided on the lower mold 3 reaches 160 ° C. in about 45 to 60 seconds, during which the temperature for the light diffusion plate A for the light diffusion plate A is passed through the first stamper 7 and the second stamper 8. The temperature of the resin plate is also increased. When it is confirmed by the temperature sensor 24 that the temperature has reached 160 ° C., the energization of the resistance heating plates 16 of the lower mold 3 and the upper mold 6 is terminated. However, actually, even after the current supply to the resistance heating plate 16 is terminated, the temperature of the resistance heating plate 16 further rises by overshooting from 160 ° C. due to residual heat for a while.
[0033]
Then, when the temperature of the resistance heating plate 16 reaches 160 ° C., the rod 15 of the hydraulic cylinder 14 which is a separating means for the lower die 3 and the upper die 6 is simultaneously contracted. When it is confirmed that the resistance heating plate 16 has come into contact with the cooling plate 9 via the insulator due to the contraction of the rod 15 of the hydraulic cylinder 14, the pressure cylinder (not shown) is controlled to lower the ram 4 again. Is started, and the resin flat plate for the light diffusion plate A is pressed at 3 MPa. Thereby, the resin flat plate for the light diffusion plate A is heated and cooled while being pressed by the first stamper 7 and the second stamper 8. Then, it is checked whether the temperature of the resistance heating plate 16 has reached 50 ° C., and when the temperature has reached 50 ° C., the pressurization is completed, the pressurizing cylinder (not shown) is controlled, the ram 4 is raised, and the light diffusing plate is raised. Release A. At about the same time, the pressure in the molding space 26 is released, and when the pressure of a barometer (not shown) becomes normal pressure, the molding space 26 is opened to the outside air, and the light diffusion plate A for which press molding has been completed is taken out.
[0034]
In the present invention, the temperature of the mold when the pressing and heating of the resin flat plate for the light diffusion plate A is started is determined by the heat deformation temperature (ASTM D638 (1)) of the resin flat plate for the light diffusion plate A to be press-molded. (Approximately 0.82 MPa): substantially the same as the glass transition temperature (Tg) of the resin flat plate). It is desirable to do. Therefore, since the thermal deformation temperature of the acrylic resin flat plate for the light diffusion plate A used in this embodiment is about 95 ° C., the temperature at which pressurization is started is preferably 105 ° C. to 175 ° C., more preferably 155 ° C. 165 ° C is preferred. When a polycarbonate resin plate is press-molded, its heat deformation temperature (ASTM D638 (1.82 MPa)) is about 135 ° C., and therefore, the temperature at which pressurization is started is preferably 145 ° C. to 215 ° C., and furthermore 195 ° C to 205 ° C is preferred. When the temperature at the beginning of pressurization is higher than the thermal deformation temperature, good transfer can be performed on the surface of the light diffusion plate A, and the temperature of the first stamper 7 and the second stamper 8 at the end of press molding is reduced. By dropping below the thermal deformation temperature, press molding is completed in a state where the shape of the formed concavo-convex pattern is stable.
[0035]
In the method for press-molding the light diffusion plate A of the present invention, the pressure applied to the resin flat plate for the light diffusion plate A is preferably in the range of about 0.5 MPa to 5 MPa, and the pressing time is 60 seconds to 150 seconds. The degree is a preferable range. The relationship between the heating temperature, the pressurizing time, and the pressing force is closely correlated. For example, when the heating temperature is reduced, the pressing force and / or the pressurizing time are increased. Further, the degree of vacuum when pressing the resin flat plate for the light diffusion plate A is preferably about 10 hPa to 50 hPa, but the pressure may be lower than the above or at a normal pressure. Further, the resin flat plate for the light diffusion plate A carried into the press forming apparatus 1 may be a pre-heated resin flat plate at a predetermined temperature, instead of using a normal temperature one. May be cut before the temperature of the resin does not drop, and may be carried into the press forming apparatus 1.
[0036]
The present invention is not limited to this embodiment, and various changes can be made within the scope of the technical idea. Next, another embodiment is shown in FIG. In the example shown in FIG. 4C, the shape of the die of the extruder is changed, and the number, direction, and pitch of the fluorescent tubes 103 are previously matched to the portion A3 of the light diffusion plate A facing the light source. This is an example in which a resin plate B for a light diffusion plate having a thick curved protruding portion B1 formed thereon is obtained, and press molding is performed on the resin plate B for the light diffusion plate. In this alternative embodiment, the resin plate used may be either a transparent plate or a milk plate mixed with a light diffusing material. In the example shown in FIG. 4, as shown in FIG. 4C, the first die 31 of the press forming apparatus 1 is provided with a nest 32 that follows the shape of the protruding portion B1. The insert 32 is formed so that it can be inserted into the dovetail groove 33 of the first mold 31 from the side, and the pressing surface 34 has an uneven pattern formed on a curved protruding portion B1 of the resin plate B for a light diffusion plate. Rough surface processing has been performed. In addition, a cartridge heater 35 is inserted inside the insert 32 in order to set the pressing surface 34 for forming a concavo-convex pattern to a higher temperature than the others.
[0037]
Further, as shown in FIG. 4D, a resin plate C for a light diffusion plate having a curved groove C1 formed in advance in a portion A3 of the light diffusion plate A facing the light source unit is obtained. Press molding may be performed on the resin plate C. Also in this case, similarly to the above, the first die 36 is provided with a nest 37 for forming a concavo-convex pattern particularly at the central portion C2 of the curved groove portion C1. Further, for pressing the curved protruding portion B1 of the resin plate B for the light diffusing plate and the curved groove C1 of the resin plate C for the light diffusing plate, the first stamper 7 which is not flat is used. The first stamper 7 is not limited to one for the first mold. Further, in another embodiment shown in FIG. 4, press forming may be performed by the second stamper 8 on the emission surface A2 of the light diffusion plate A.
[0038]
Further, the resin plate for the light diffusion plate A uses a resin plate having a uniform thickness, and the thickness and shape of the resin plate are changed by the first mold and the second mold to provide a curved uneven surface. You may. In this case, the resin flat plate for the light diffusion plate A is heated and pressurized by the press molding apparatus 1, so that the light diffusion plate A provided with a number of curved uneven surfaces corresponding to the fluorescent tubes 103 of the light diffusion plate A is provided. Is obtained. In this case, the first stamper 7 may be attached to the first mold, or the surface of the mold itself may be formed as a rough surface.
In the present invention, the first mold or the first stamper 7 forms on the incident surface A1 of the light diffusing plate A a concavo-convex pattern for restricting the incidence of light from the light source, but on the exit surface A2 side. An uneven pattern for making the light emitted from the light diffusion plate A uniform may be partially formed. In that case, it is desirable that an uneven pattern is formed on a portion of the light diffusion plate A between the back surface near the light source and the back near another light source.
[0039]
【The invention's effect】
According to the present invention, it is possible to form a light diffusion plate made of a thermoplastic resin on a portion of the light incident surface opposite to the light source portion arrangement position, in which a concavo-convex pattern in which the incidence of light from the light source portion is restricted as compared with other portions. By molding the first mold, the first mold and the second mold are heated while being pressed at a temperature equal to or higher than the thermal deformation temperature of the thermoplastic resin between the opposing second mold, and then cooled and molded. It is possible to form a light diffusing plate in which a fine concavo-convex pattern is formed as intended and light that is incident from the light source unit can be uniformly emitted to the liquid crystal plate. In addition, a light diffusion plate having a small thickness and a large area, which has been difficult particularly by injection molding, can be formed by press molding without unevenness of light emitted from the light diffusion plate and warpage of the light diffusion plate. Furthermore, by forming the concave / convex pattern with the stamper, a fine concave / convex pattern can be freely formed, and when modifying or changing the concave / convex pattern, it is easy to respond by replacing only the stamper without changing the entire mold. become.
[Brief description of the drawings]
FIG. 1 is a diagram showing a state where a light diffusing plate of the present invention is attached to a liquid crystal unit.
FIG. 2 is a cross-sectional view of the light diffusing plate press-forming apparatus of the present invention.
FIG. 3 is a view showing a concavo-convex pattern forming portion of a first stamper attached to the light diffusing plate forming apparatus of the present invention.
FIG. 4 is a diagram showing a resin plate for a light diffusion plate and a first mold according to another embodiment of the present invention.
[Explanation of symbols]
1 ... Press forming equipment
2 ...... Bed
3 ……… Lower mold
4 ……… Ram
5 Upper movable plate
6 ……… Upper mold
7 ...... First stamper
7a: Uneven pattern forming part
7b ...... Part without uneven pattern forming part
7c ...... fine uneven pattern forming part
7d: an uneven pattern forming portion with increased density and / or size
8 ……… Second stamper
9 Cooling board
10 Temperature control medium passage
11, 21 ...... Surface
12, 18, 22 ... rubber sheet
13 ... recess
14 …… Hydraulic cylinder
15 ...... Rod
16 ...... Resistance heating plate
17 ...... Support part
19a, 19b ... terminal part
20 ...... Wire
23 …… back side
24 ...... Temperature sensor
25 ... Frame
26 ...... Molding space
27a, 27b ... tube
31, 36… First type
32 ...... Nested
33 ... Dovetail
34 …… Pressing surface
35 ...... Cartridge heater
101 Liquid crystal unit
102 ...... Liquid crystal panel
103… Fluorescent tube
104 …… Prism sheet
A: Light diffusion plate
A1… incident surface
A2 ... Emission surface
A3 ... The part facing the light source unit
A4 ... other parts
A5: Uneven pattern
B, C: resin plate for light diffusion plate
B1 Projection
C1 Groove

Claims (8)

A light diffuser made of a thermoplastic resin which is provided between the liquid crystal plate and the light source unit in parallel with the liquid crystal plate, diffuses light of the light source unit incident from an incident surface, and emits the light from the emission surface toward the liquid crystal plate. A plate press forming apparatus,
In the vicinity of a portion facing the light source portion on the incident surface of the light diffusion plate,
A first mold capable of forming a concavo-convex pattern that restricts the incidence of light from the light source unit from other parts,
A second mold facing the first mold,
Heating means provided on the first mold and the second mold, respectively, for heating the mold to a temperature equal to or higher than the thermal deformation temperature of the thermoplastic resin,
Cooling means for cooling after heating the first mold and the second mold during one molding cycle by the heating means,
And a pressurizing means for pressing the light diffusion plate between the first and second dies by moving the first and second dies toward and away from each other. In the first type,
A first stamper capable of forming a fine concavo-convex pattern that restricts the incidence of light from the light source unit from other portions is attached in the vicinity of a portion facing the light source unit on the incident surface of the light diffusion plate. The press forming apparatus for a light diffusion plate according to claim 1, wherein: 3. The light according to claim 1, wherein a second stamper capable of forming a fine concavo-convex pattern substantially uniformly on an emission surface of the light diffusion plate is attached to the second mold. Diffusion plate press forming equipment. The apparatus according to claim 3, wherein the heating means comprises a resistance heating plate provided to be separated from the cooling means. A transparent acrylic resin flat plate, a transparent polycarbonate resin flat plate, and a transparent cycloolefin resin flat plate having no light diffusing material, using the light diffusing plate press forming apparatus according to any one of claims 1 to 4. A press-forming method for a light diffusion plate, wherein heating and cooling are performed while applying pressure to a crab. An acrylic resin using the light diffusion plate press-molding apparatus according to any one of claims 1 to 5, wherein at least fine particles made of a silicon resin or pigments made of titanium oxide are mixed as a light diffusion material. A method for press-molding a light diffusion plate, wherein heating and cooling are performed while applying pressure to any of a flat plate, a polycarbonate resin flat plate, and a cycloolefin resin flat plate. The resin flat plate of the acrylic resin or the like has a substantially rectangular shape in a plan view, and has a length in a diagonal direction of 150 to 400 times the thickness thereof. Press forming method of the light diffusing plate according to the above. An acrylic resin having a light diffusion plate press-molding device according to claim 1, wherein a groove or a protrusion corresponding to the number and direction of the light source units is formed in advance on a portion of the incident surface opposite to the arrangement position of the light source units. A method for press-molding a light diffusion plate, wherein heating and cooling are performed while applying pressure to any of a flat plate, a polycarbonate resin flat plate, and a cycloolefin resin flat plate.

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