JP2013244717A - Optical sheet manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical sheet manufacturing method and an optical sheet processing device that can prevent turnings and chips from being mixed with and stuck on an optical sheet.SOLUTION: When a rugged part 9 is formed on a light incident end face 7a of a light guide plate 7 using an optical sheet processing device 20, a transfer mold 24 is heated first with the light guide plate 7 placed on a stage 21. Further, certain pressure is applied to the stage 21 to press a transfer surface 25a of a solid roll part 25 of the transfer mold 24 and the light incident surface 7a of the light guide plate 7 against each other. In this state, the stage 21 is moved to the transfer mold 24 at right angles to the pressure application direction and the solid roll part 25 is rotated to transfer a transfer rugged part 26 of the solid roll part 25 to the light incident end face 7a of the light guide plate 7. Consequently, the rugged part 9 corresponding to the transfer rugged part 26 is formed on the light incident end face 7a of the light guide plate 7.

Description

  The present invention relates to an optical sheet manufacturing method for manufacturing an optical sheet having an uneven portion on a light incident end surface, and an optical sheet processing apparatus for forming an uneven portion on a light incident end surface of an optical sheet.

  An example of the optical sheet is a light guide plate used in a backlight unit of a liquid crystal display device. In the edge-light type backlight unit, a plurality of light sources are arranged in an array facing the light incident end face of the light guide plate, and light incident from the light incident end face of the light guide plate is emitted from the light exit surface, thereby liquid crystal Illuminate the display panel. However, in the edge light type backlight unit, luminance unevenness occurs in the illumination light emitted from the vicinity of the light incident end surface of the light exit surface of the light guide plate.

  In order to solve such a problem, for example, as described in Patent Document 1, a technique in which a cut and polished surface is formed on a light incident end surface of a light guide plate is known. The cutting and polishing surface described in Patent Document 1 is a rough surface having a large number of fine vertical irregularities extending in a direction perpendicular to the light emitting surface of the light guide plate.

JP 2010-182478 A

  However, in the above prior art, the cutting and polishing surface is formed on the light incident end surface of the light guide plate by machining using a machine tool such as a milling machine, NC router, or planar, so that chips are generated by cutting. . For this reason, cutting powder mixes and adheres to the light guide plate, resulting in poor quality.

  The objective of this invention is providing the optical sheet manufacturing method and optical sheet processing apparatus which can prevent mixing and adhesion of the swarf to an optical sheet.

  The present invention is an optical sheet manufacturing method for manufacturing an optical sheet made of a thermoplastic resin and having an uneven portion on the light incident end surface, and has a transfer surface for providing the uneven portion on the light incident end surface of the optical sheet. The method includes a step of preparing a transfer mold and a step of forming an uneven portion on the light incident end surface by pressing the transfer surface and the light incident end surface with the transfer mold heated. is there.

  Thus, in the optical sheet manufacturing method of the present invention, the transfer mold of the transfer mold and the optical sheet of the optical sheet are heated in a state where the transfer mold having the transfer surface for imparting the uneven portion to the light incident end face of the optical sheet is heated. Unlike the case where the uneven portions are formed by cutting by forming the uneven portions on the light incident end surfaces of the optical sheet by pressing the light incident end surfaces to each other, chips are not generated. Thereby, mixing and adhesion of swarf to the optical sheet can be prevented. Further, when the uneven portion is formed by cutting, the processing time tends to be long. However, in the present invention using the transfer mold, the heating temperature of the transfer mold, the transfer surface of the transfer mold, and the optical sheet By adjusting the pressing pressure between the end faces, the processing time can be shortened.

  Preferably, in the step of forming the concavo-convex portion on the light incident end face, the transfer mold is heated to a temperature not lower than the Vicat softening temperature of the thermoplastic resin and not higher than the Vicat softening temperature of the thermoplastic resin + 50 ° C. By setting the heating temperature of the transfer mold to be equal to or higher than the Vicat softening temperature of the thermoplastic resin, the thermoplastic resin is moderately softened, so that the optical sheet is prevented from cracking and an uneven portion is formed on the light incident end face of the optical sheet. It can transfer well. In addition, by setting the heating temperature of the transfer mold to the Vicat softening temperature of the thermoplastic resin + 50 ° C. or less, the melt flow of the thermoplastic resin is prevented, so the elastic modulus of the thermoplastic resin is lowered and the optical sheet is deformed. And the transfer mold is hardly contaminated.

  Preferably, the transfer mold has a metal roll portion, and the peripheral surface of the roll portion is a transfer surface, and in the step of forming the uneven portion on the light incident end surface, the transfer surface and the light incident end surface The roll part is rotated in a state where they are pressed together, and the roll part is moved relative to the optical sheet along the light incident end face of the optical sheet to form an uneven part on the light incident end face. In this case, when the transfer surface of the transfer mold (the peripheral surface of the roll part) and the light incident end surfaces of the optical sheet are pressed against each other, they are not in surface contact but in line contact. The pressure can be reduced.

  More preferably, the transfer surface is provided with a convex or concave portion for transfer having a prism shape or a lenticular shape, the pitch of the concave and convex portion for transfer is 10 μm to 500 μm, and the height of the concave and convex portion for transfer is 10 μm to 300 μm. It is. By making the shape of the concavo-convex portion for transfer into a prism shape or a lenticular shape, a transfer surface having the concavo-convex portion for transfer can be made relatively easily. Also, by setting the pitch of the concavo-convex portion for transfer to 10 μm to 500 μm and adjusting the height of the concavo-convex portion for transfer to 10 μm to 300 μm, the concavo-convex portion is transferred to the light incident end face of the optical sheet at a desired transfer rate can do.

  Preferably, in the step of forming the concavo-convex portion on the light incident end surface, the transfer surface and the light incident end surface are pressed against each other with a pressure of 0.05 MPa to 50 MPa. By setting the pressing pressure to 0.05 MPa or more, the concavo-convex portion can be satisfactorily transferred to the light incident end face of the optical sheet. Moreover, the crack of an optical sheet can be prevented by making pressing pressure into 50 Mpa or less.

  As the thermoplastic resin, it is preferable to use an amorphous resin having high dimensional accuracy, impact strength, and transparency.

  The present invention also provides an optical sheet processing apparatus for forming an uneven portion on a light incident end surface of an optical sheet made of a thermoplastic resin, the stage supporting the optical sheet, and the light incident end surface of the optical sheet supported by the stage. A transfer mold having a transfer surface for providing an uneven portion, a heating means for heating the transfer mold, a pressure applying means for applying pressure so as to press the transfer surface and the light incident end surfaces, and a light incident end surface And a driving means for driving at least one of a stage and a transfer mold so as to form an uneven portion.

  By using such an optical sheet processing apparatus of the present invention, the above-described optical sheet manufacturing method can be carried out. As a result, chips are not generated as described above, and therefore, mixing and adhesion of chips to the optical sheet can be prevented. Further, as described above, the processing time can be shortened.

  Preferably, the transfer mold has a metal roll part, and the peripheral surface of the roll part is a transfer surface, and the driving means is provided along the light incident end face of the optical sheet and the means for rotating the roll part. And means for moving the roll portion relative to the stage. In this case, when the transfer surface of the transfer mold and the light incident end surfaces of the optical sheet are pressed against each other, both are in a line contact state, so that the pressing pressure can be reduced.

  Preferably, the apparatus further includes a clamping unit that clamps the optical sheet with respect to the stage. In this case, in a state where the optical sheet is clamped with respect to the stage by the clamping means, the pressure applied by the pressure applying means does not escape upward, so that the transfer surface of the transfer mold and the incident light of the optical sheet The end faces can be effectively pressed against each other.

  According to the present invention, it is possible to prevent chips from being mixed and adhered to the optical sheet. As a result, the quality of the optical sheet can be stabilized and the yield can be improved.

It is a schematic sectional drawing which shows the liquid crystal display device containing the light-guide plate as an optical sheet manufactured by one Embodiment of the optical sheet manufacturing method concerning this invention. It is a perspective view of the light-guide plate shown in FIG. It is a flowchart which shows the process of manufacturing the light-guide plate shown in FIG. It is a schematic block diagram which shows the optical sheet processing apparatus used when performing a thermal transfer process to the light-incidence end surface of the light-guide plate shown in FIG. It is a figure which shows the uneven | corrugated | grooved part formed in the surrounding surface of the rigid roll part of the transfer metal mold | die shown in FIG. It is a schematic block diagram which shows the modification of the optical sheet processing apparatus shown in FIG. It is a schematic block diagram which shows the other modification of the optical sheet processing apparatus shown in FIG. It is a schematic block diagram which shows the modification of the optical sheet processing apparatus shown in FIG. It is a figure which shows the other uneven | corrugated | grooved part formed in the surrounding surface of the rigid roll part of the transfer metal mold | die shown in FIG. It is a table | surface which shows the conditions and result when an uneven | corrugated | grooved part is heat-transfer-processed on the light-incidence end surface of a light-guide plate with a transfer metal mold | die.

  Hereinafter, an optical sheet manufacturing method and an optical sheet processing apparatus according to 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 reference numerals, and redundant description is omitted.

  FIG. 1 is a schematic cross-sectional view showing a liquid crystal display device including a light guide plate as an optical sheet manufactured by an embodiment of an optical sheet manufacturing method according to the present invention. In the figure, a liquid crystal display device 1 according to this embodiment is used for a liquid crystal television, for example. The liquid crystal display device 1 includes a liquid crystal panel 2 and an edge-type backlight unit 3 disposed on the back side of the liquid crystal panel 2. The thickness of the liquid crystal panel 2 is, for example, about 1.8 mm.

  The backlight unit 3 has a box-shaped metal backlight housing 4. A plurality of electronic components 5 are provided on the back surface (back surface) of the backlight housing 4 via a substrate (not shown). A plurality of LEDs 6 that irradiate light are attached to the opposing inner wall surfaces of the backlight housing 4.

  In the backlight housing 4, a light guide plate 7 having a rectangular cross section for guiding the light emitted from the LEDs 6 to the liquid crystal panel 2 is accommodated via a reflection sheet 8. The reflection sheet 8 is disposed on the back surface (back surface) side of the light guide plate 7. As shown in FIG. 2, the light incident end surface 7 a of the light guide plate 7 is provided with a concavo-convex portion 9 having a substantially corrugated cross section. The thickness of the light guide plate 7 is, for example, 3 mm.

  The light guide plate 7 is made of a thermoplastic resin. Specifically, the light guide plate 7 is made of an amorphous resin having high dimensional accuracy, impact strength, and transparency. Examples of the amorphous resin include polymethyl methacrylate resin (PMMA), polystyrene (PS), polycarbonate (PC), and cycloolefin polymer (COP).

  The light emitted from the LED 6 is incident on the light incident end surface 7 a of the light guide plate 7. The back surface of the light guide plate 7 is a reflective surface that reflects the light emitted from the LED 6, and the front surface of the light guide plate 7 is a light exit surface that emits the light emitted from the LED 6 and the light reflected by the reflective surface. It has become. The back surface (reflection surface) of the light guide plate 7 has a structure that easily reflects and scatters light, such as dot pattern printing with ink. Depending on the application, a lenticular shape, a prism shape, or the like may be formed on the light exit surface.

  On the front side of the light guide plate 7, an optical film group 10 formed by laminating a plurality of (here, three) optical films is disposed. The thickness of the optical film group 10 is, for example, about 0.2 mm. The edges of the light guide plate 7 and the optical film group 10 are fixed to the backlight housing 4 by a frame body 11 made of resin (for example, PC). The liquid crystal panel 2 is fixed to the backlight unit 3 by a metal frame body 12.

  FIG. 3 is a flowchart showing a process for manufacturing the light guide plate 7. In the figure, first, a light guide plate original plate is produced by a melt extrusion sheet forming process or the like (step S101). Subsequently, the light guide plate original plate is roughly cut with a panel saw, a running saw, or the like to obtain the light guide plate 7 (step S102). Subsequently, mirror processing is performed on the light incident end surface 7a of the light guide plate 7 using a mirror processing machine (step S103). Then, the uneven | corrugated | grooved part 9 is formed in the light-incidence end surface 7a by performing thermal transfer processing to the light-incidence end surface 7a of the light-guide plate 7 (step S104). Note that step S103 is not necessarily performed.

  FIG. 4 is a schematic configuration diagram illustrating the optical sheet processing apparatus 20 used when performing Step S104 of FIG. In the figure, an optical sheet processing apparatus 20 includes a stage 21 that supports the light guide plate 7, and a clamp plate 22 that presses and clamps the light guide plate 7 placed on the stage 21 against the stage 21 from above. It has. Two positioning projections 23 for projecting the light guide plate 7 are provided on the upper surface of the stage 21.

  The optical sheet processing apparatus 20 further includes a transfer mold 24 that performs thermal transfer on the light incident end surface 7 a of the light guide plate 7 placed on the stage 21. The transfer mold 24 has a rotatable metal rigid roll portion 25. On the peripheral surface of the rigid roll portion 25, a transfer uneven portion 26 is formed along the circumferential direction of the rigid roll portion 25. The peripheral surface of the rigid roll portion 25 is a transfer surface 25 a for providing the uneven portion 9 to the light incident end surface 7 a of the light guide plate 7. The transfer uneven portion 26 is formed in a prism shape (triangular prism shape) with respect to the axial direction of the rigid roll portion 25 (see FIG. 5).

  As shown in FIG. 5, the pitch (width) P of the concavo-convex portion for transfer 26 is preferably 10 μm to 500 μm, more preferably 10 μm to 200 μm. The height (depth) H of the concavo-convex portion for transfer 26 is preferably 10 μm to 300 μm according to the pitch P of the concavo-convex portion for transfer 26. In FIG. 5, for convenience, the transfer uneven portions 26 are shown to be linearly arranged.

  Further, the optical sheet processing apparatus 20 is configured to press the heating unit 27 that heats the transfer mold 24, the transfer surface 25 a of the rigid roll unit 25 of the transfer mold 24, and the light incident end surface 7 a of the light guide plate 7. A pressure applying unit 28 that applies pressure to the pressure 21, a moving drive unit 29 that moves the stage 21 in a direction perpendicular to the direction of pressure application (the direction of arrow A in FIG. 4), and a rotation that rotates the rigid roll unit 25. And a drive unit 30.

  When the uneven portion 9 is formed on the light incident end surface 7a of the light guide plate 7 using such an optical sheet processing apparatus 20, first, one light guide plate 7 is placed on the stage 21, and the clamp plate 22 is in that state. Thus, the light guide plate 7 is clamped. Note that a masking film may be bonded to the light guide plate 7 mounted on the stage 21 to prevent scratches.

  Then, the transfer mold 24 is heated by the heating unit 27. At this time, the heating temperature of the transfer mold 24 is preferably not less than the Vicat softening temperature of the thermoplastic resin forming the light guide plate 7 and not more than the Vicat softening temperature of the thermoplastic resin + 50 ° C. or less. It is more preferable that the Vicat softening temperature of the resin + 5 ° C. or higher and the Vicat softening temperature of the thermoplastic resin + 35 ° C. or lower. For example, when PMMA is used as the thermoplastic resin, the Vicat softening temperature of PMMA is 104 ° C. For this reason, the heating temperature of the transfer mold 24 is preferably 104 ° C to 154 ° C, more preferably 110 ° C to 140 ° C, and further preferably 120 ° C to 130 ° C.

  Further, by applying a constant pressure to the stage 21 by the pressure application unit 28, the transfer surface 25 a of the rigid roll unit 25 and the light incident end surface 7 a of the light guide plate 7 are pressed against each other. At this time, since the transfer surface 25a and the light incident end surface 7a are not in surface contact but in line contact, the pressing pressure can be reduced accordingly. The pressing pressure set at this time is preferably 0.05 MPa to 50 MPa, more preferably 0.2 MPa to 0.6 MPa. In addition, since the light guide plate 7 is clamped by the clamp plate 22, the pressing pressure does not escape above the light guide plate 7, and the transfer surface 25a and the light incident end surface 7a can be effectively pressed against each other.

  In this state, the stage 21 is moved in the direction perpendicular to the pressure application direction with respect to the transfer mold 24 by the movement drive unit 29, and the rigid roll unit 25 is rotated by the rotation drive unit 30. Is relatively moved along the light incident end surface 7 a of the light guide plate 7 while rotating, so that the transfer uneven portion 26 of the rigid roll portion 25 is transferred to the light incident end surface 7 a of the light guide plate 7. At this time, the movement of the stage 21 and the rotation of the rigid roll unit 25 are performed in synchronization. The transfer time is preferably 1 second to 10 seconds, and more preferably 1 second to 5 seconds. Thus, the uneven portion 9 corresponding to the transfer uneven portion 26 is formed on the light incident end surface 7 a of the light guide plate 7.

  In the optical sheet processing apparatus 20, by applying pressure to the stage 21, the transfer surface 25a of the rigid roll unit 25 and the light incident end surface 7a of the light guide plate 7 are pressed against each other. By applying pressure to the rigid roll unit 25, the transfer surface 25 a of the rigid roll unit 25 and the light incident end surface 7 a of the light guide plate 7 may be pressed against each other.

  FIG. 6 is a schematic configuration diagram illustrating a modified example of the optical sheet processing apparatus 20 illustrated in FIG. 4. In the figure, the optical sheet processing apparatus 20 of the present modification is configured in such a manner that the rigid roll unit 25 is perpendicular to the pressure application direction with respect to the stage 21 (in the direction of arrow B in FIG. 6) instead of the movement drive unit 29 described above. ) Is provided. Therefore, the rigid roll portion 25 itself moves along the light incident end surface 7a of the light guide plate 7 while rotating. Other configurations are the same as those shown in FIG. Even in this case, the transfer uneven portion 26 of the rigid roll portion 25 can be transferred to the light incident end surface 7 a of the light guide plate 7.

  FIG. 7 is a schematic configuration diagram illustrating another modification of the optical sheet processing apparatus 20 illustrated in FIG. 4. In this figure, the optical sheet processing apparatus 20 of this modification includes a stage 32 that supports a plurality of light guide plates 7 in a stacked state. Other configurations are the same as those shown in FIG. In this case, the concavo-convex portion for transfer 26 of the rigid roll portion 25 can be collectively transferred to the light incident end surfaces 7 a of the plurality of light guide plates 7. Therefore, productivity can be improved.

  FIG. 8 is a schematic configuration diagram illustrating a modified example of the optical sheet processing apparatus 20 illustrated in FIG. 7. In the same figure, in the optical sheet processing apparatus 20 of this modification, instead of the movement drive unit 29, the rigid roll unit 25 is moved in the direction perpendicular to the pressure application direction with respect to the stage 32 (the direction of arrow B in FIG. 8). A movement drive unit 31 for movement is provided. Other configurations are the same as those shown in FIG. Also in this case, the transfer concavo-convex portion 26 of the rigid roll portion 25 can be collectively transferred to the light incident end surfaces 7 a of the plurality of light guide plates 7.

  As described above, in the present embodiment, the transfer die 24 is heated and the transfer surface 25a of the rigid body roll portion 25 of the transfer die 24 and the light incident end surface 7a of the light guide plate 7 are pressed against each other to obtain the rigid body roll portion. Since the uneven portion for transfer 26 provided on the transfer surface 25a of 25 is transferred to the light incident end surface 7a of the light guide plate 7, the uneven portion 9 is formed on the light incident end surface 7a of the light guide plate 7. As in the case where the uneven portion 9 is formed on the light incident end surface 7a of the light guide plate 7 by mechanical cutting process or the like, chips are not generated. For this reason, since chips do not adhere to or mix in the light guide plate 7, the quality of the product is stabilized, and the yield can be improved.

  At this time, by setting the heating temperature of the transfer mold 24 to be equal to or higher than the Vicat softening temperature of the thermoplastic resin forming the light guide plate 7, the light incident end surface 7a of the light guide plate 7 is appropriately softened. The transfer uneven portion 26 can be satisfactorily transferred to the light incident end surface 7a of the light guide plate 7, and the light guide plate 7 can be prevented from being cracked. Further, since the heating temperature of the transfer mold 24 is set to the Vicat softening temperature of the thermoplastic resin forming the light guide plate 7 + 50 ° C. or less, the melt flow of the thermoplastic resin is prevented, so the elastic modulus of the thermoplastic resin. Is suppressed, and the light guide plate 7 is hardly deformed. In addition, significant contamination of the transfer mold 24 can be prevented.

  Further, by setting the pressing pressure of the transfer surface 25 a of the rigid roll portion 25 and the light incident end surface 7 a of the light guide plate 7 to 0.05 MPa or more, the transfer uneven portion 26 of the rigid roll portion 25 is made to be the light incident end surface of the light guide plate 7. 7a can be transferred more satisfactorily. Moreover, it can further prevent that the light guide plate 7 is cracked by setting the pressing pressure of the transfer surface 25a of the rigid roll portion 25 and the incident end surface 7a of the light guide plate 7 to 50 MPa or less.

  Furthermore, when the uneven portion 9 is formed on the light incident end surface 7a of the light guide plate 7 by cutting, it takes time to process the fine uneven portion 9, and it is difficult to reduce the pitch of the uneven portion 9. There is a problem that the uneven portion 9 is changed due to wear of the cutting tool. In this embodiment, since the uneven portion 9 is formed on the light incident end surface 7a of the light guide plate 7 by thermal transfer processing using the transfer mold 24, the heating temperature of the transfer mold 24, the transfer surface 25a of the rigid roll portion 25, and By controlling the pressing pressure and pressing time of the light incident end face 7a of the light guide plate 7, the processing time can be easily shortened. Further, by producing and using an arbitrary transfer mold, it is possible to form the uneven portions 9 having various shapes, and it is possible to reduce the pitch of the uneven portions 9.

  The present invention is not limited to the above embodiment. For example, in the above-described embodiment, the prism-shaped transfer uneven portion 26 is formed on the transfer surface 25a of the rigid roll portion 25. However, the shape of the transfer uneven portion 26 is not particularly limited to the prism shape, and FIG. A lenticular shape as shown in FIG. Even in this case, it is preferable that the pitch P of the uneven portions for transfer 26 is 10 μm to 500 μm and the height H of the uneven portions for transfer 26 is 10 μm to 300 μm. Moreover, as a shape of the uneven | corrugated | grooved part 9, a pyramid shape, a mat | matte, etc. may be sufficient besides that.

  In the above embodiment, the transfer mold 24 has the rigid roll portion 25, and the peripheral surface of the rigid roll portion 25 is the transfer surface 25 a for providing the uneven portion 9 to the light incident end surface 7 a of the light guide plate 7. However, the transfer mold to be used is not particularly limited thereto. For example, the shape of the transfer mold may be a flat plate shape, and one side surface of the transfer mold may be a transfer surface for providing the uneven portion 9 to the light incident end surface 7 a of the light guide plate 7.

  Furthermore, although the said embodiment manufactures the light-guide plate 7 comprised by the backlight unit 3 of the liquid crystal display device 1 used for a liquid crystal television, the optical sheet manufacturing method of this invention is for illumination, for example, It can also be applied to the production of an optical sheet as a decorative light guide plate.

  Hereinafter, an example of the optical sheet manufacturing method according to the present invention will be described.

  Using a transfer mold having a rigid roll portion, the uneven portion was thermally transferred to the light incident end face of the light guide plate. The used light guide plate is formed of PMMA (Vicat softening temperature: 104 ° C.). The temperature of the light guide plate is 25 ° C. On the peripheral surface of the rigid roll portion, a prism-shaped transfer uneven portion is provided. As the transfer mold, the apex angle θ (see FIG. 5) of the transfer uneven portion of the rigid roll portion is 110 degrees, and the pitch P of the transfer uneven portion is 100 μm, 200 μm, and 300 μm. . When the transfer unevenness pitch P is 100 μm, the transfer unevenness height H is 34.7 μm, and when the transfer unevenness pitch P is 200 μm, the transfer unevenness height. When H is 69.3 μm and the pitch P of the uneven portions for transfer is 300 μm, the height H of the uneven portions for transfer is 104.0 μm.

  As shown in FIG. 10, the heating temperature of the transfer mold was 110 ° C., 120 ° C., 130 ° C., and 140 ° C. The pressing pressure of the transfer surface of the rigid roll portion and the light incident end surface of the light guide plate was either 0.4 MPa or 0.6 MPa. The pressing time of the transfer surface of the rigid roll portion and the light incident end surface of the light guide plate was either 1 second or 5 seconds.

FIG. 10 shows the result of thermal transfer processing of the concavo-convex portion on the light incident end face of the light guide plate by the above transfer mold. FIG. 10 (a) is a table showing the results when a transfer mold having a transfer unevenness portion of the rigid roll portion having a pitch of 300 μm is used, and the pitches of the uneven portions of the light guide plate are all 300 μm. The height and the transfer rate are as shown in the table. FIG. 10 (b) shows the results when a transfer mold having a transfer uneven portion of the rigid roll portion having a pitch of 200 μm is used. The pitch of the uneven portion of the light guide plate is all 200 μm, and the height of the uneven portion. The transfer rate is as shown in the table. FIG. 10C shows the result when a transfer mold having a transfer unevenness portion of the rigid roll portion having a pitch of 100 μm is used. The unevenness portion pitches of the light guide plate are all 100 μm, and the height of the unevenness portion. The transfer rate is as shown in the table. The transfer rate is expressed by the following formula (see FIG. 5).
Transfer rate (%) = height / roughness height Hr of light guide plate / height / recession height H of rigid body roll portion

  As can be seen from FIG. 10, when a transfer mold having a transfer rugged portion pitch of 100 μm and 200 μm in the rigid roll portion is used, a transfer mold having a transfer rugged portion pitch of 300 μm in the rigid roll portion is used. Compared with the case, the transfer rate tends to be higher. Also, when the heating temperature of the transfer mold is 120 ° C. and 130 ° C., the transfer rate tends to be higher than when the heating temperature of the transfer mold is 110 ° C. and 140 ° C.

DESCRIPTION OF SYMBOLS 7 ... Light guide plate (optical sheet), 7a ... Light incident end surface, 9 ... Uneven part, 20 ... Optical sheet processing apparatus, 21 ... Stage, 22 ... Clamp plate (clamp means), 24 ... Transfer die, 25 ... Rigid body roll , 25a ... peripheral surface (transfer surface), 26 ... transfer uneven portion, 27 ... heating portion (heating means), 28 ... pressure application portion (pressure application means), 29 ... movement drive portion (drive means), 30 ... Rotation drive unit (drive unit), 31... Movement drive unit (drive unit), 32... Stage, P... Pitch, H.

Claims (9)

An optical sheet manufacturing method for manufacturing an optical sheet made of a thermoplastic resin and having an uneven portion on the light incident end face,
Preparing a transfer mold having a transfer surface for imparting the uneven portion to the light incident end surface of the optical sheet;
Forming the concave and convex portions on the light incident end surface by pressing the transfer surface and the light incident end surface with the transfer mold heated.   In the step of forming the concavo-convex portion on the light incident end face, the transfer mold is heated to a temperature not lower than the Vicat softening temperature of the thermoplastic resin and not higher than the Vicat softening temperature of the thermoplastic resin + 50 ° C. The method for producing an optical sheet according to claim 1. The transfer mold has a metal roll part,
The peripheral surface of the roll part is the transfer surface,
In the step of forming the concavo-convex portion on the light incident end surface, the roll portion is rotated along the light incident end surface of the optical sheet while rotating the roll portion with the transfer surface and the light incident end surfaces pressed against each other. The optical sheet manufacturing method according to claim 1, wherein the concavo-convex portion is formed on the light incident end surface by moving the illuminant relative to the optical sheet. The transfer surface is provided with a prism-shaped or lenticular-shaped concavo-convex portion for transfer,
The pitch of the uneven portions for transfer is 10 μm to 500 μm,
The optical sheet manufacturing method according to any one of claims 1 to 3, wherein a height of the concavo-convex portion for transfer is 10 µm to 300 µm.   5. The step of forming the concavo-convex portion on the light incident end surface presses the transfer surface and the light incident end surfaces with a pressure of 0.05 MPa to 50 MPa. Optical sheet manufacturing method.   The optical sheet manufacturing method according to claim 1, wherein an amorphous resin is used as the thermoplastic resin. An optical sheet processing apparatus for forming an uneven portion on a light incident end face of an optical sheet made of a thermoplastic resin,
A stage for supporting the optical sheet;
A transfer mold having a transfer surface for imparting the concavo-convex portion to the light incident end surface of the optical sheet supported by the stage;
Heating means for heating the transfer mold;
Pressure applying means for applying pressure so as to press the transfer surface and the light incident end surfaces;
An optical sheet processing apparatus comprising: a drive unit that drives at least one of the stage and the transfer mold so as to form the uneven portion on the light incident end surface. The transfer mold has a metal roll part,
The peripheral surface of the roll part is the transfer surface,
The said drive means has a means to rotate the said roll part, and a means to move the said roll part relatively with respect to the said stage along the light-incidence end surface of the said optical sheet, It is characterized by the above-mentioned. The optical sheet processing apparatus as described. 9. The optical sheet processing apparatus according to claim 7, further comprising clamping means for clamping the optical sheet to the stage.

Images