JP2009113405A - Optical film-pressing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical film-pressing device enabling an optical film to be stretched to be held stably. <P>SOLUTION: The optical film-pressing device 30 has at least a frame part 34 and a belt unit 36. The frame part 34 is attachable to a stretching part 18. The belt unit is supported by the frame part 34 so as to contact a pressing roller 183 compressively. The belt unit 36 has an endless belt 38 arranged so as to contact the pressing roller compressively via the optical film 11, and a plurality of guide rollers (40, 42, 44, 46, 48, 50 and 52) tensed with the endless belt 38. As a result, the pressing rollers do not contact each other as nip rollers do, and the endless belt 38 becomes to contact the pressing roller 183 via the optical film 11. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical film that is arranged so as to press-contact with a pressure roller of a stretching section configured to contact an optical film via the optical film, and to apply pressure to the optical film to be stretched The present invention relates to a pressure device.

Conventionally, a nip roll method has been widely used as a method for stretching an optical film. Some prior arts employ a configuration in which an optical film is guided to a stretching portion and stretched by a plurality of sets of nip rollers in which the ratio of peripheral speeds is appropriately set in the stretching portion (for example, Patent Documents). 1). The invention according to Patent Document 1 employs a stretching technique that takes advantage of the advantages of the dry stretching method and the wet stretching method in the production of an optical film by the nip roll method.
JP 2002-350638 A

  One important factor in stretching the optical film is to stabilize the force that holds the optical film at the nip portion of a plurality of sets of nip rollers that apply tension to the optical film. This holding force is represented by the product of the surface pressure per unit area in the nip portion, the area of the nip portion, and the friction coefficient between the roller and the optical film. For this reason, in order to stabilize the above-mentioned holding force, it is important to stabilize the surface pressure per unit area, the area of the nip portion, and the friction coefficient between the roller and the optical film.

  However, in the conventional technique, the area of the narrow nip portion may fluctuate due to the rotation of the roller, and the holding force of the optical film in the nip portion may not be stable. For this reason, it is preferable to increase the area of the nip portion, but it was difficult to effectively increase the area of the nip portion even if conventional design changes such as an increase in the diameter of the roller and improvement of the surface member of the roller were performed. .

  An object of the present invention is to provide an optical film pressurizing apparatus that makes it possible to stably hold an optical film to be stretched.

  The optical film pressurizing apparatus according to the present invention is configured so as to press-contact with a pressurizing roller of a stretching unit configured so that an optical film to be stretched contacts with the optical film via the optical film. The optical film pressurizing device includes at least a frame portion and a belt unit. The frame part is configured to be attachable to the extending part. For example, in a stretching system that employs a dry stretching method, the frame portion is attached to a frame that defines the stretching portion, and in a stretching system that employs a wet stretching method, the frame portion is attached to a bathtub provided in the stretching portion. The shape, structure, size and the like of the frame portion are not particularly limited as long as the frame portion is stably fixed to the extending portion while supporting the belt unit.

  The belt unit is supported by the frame portion so as to be in pressure contact with the pressure roller. The belt unit includes an endless belt disposed so as to be in pressure contact with the pressure roller via an optical film, and a plurality of guide rollers that stretch the endless belt. The material of the endless belt is preferably polyurethane, but a steel belt can also be used.

  In this configuration, the pressure rollers are not brought into pressure contact with each other as in the nip roll method, but the endless belt is brought into pressure contact with the pressure roller. Because the endless belt can easily adjust the holding angle of the pressure contact surface with the pressure roller by changing the position of a plurality of guides that stretch the endless belt, the area of the pressure contact surface that presses the optical film can be greatly expanded. Is possible. For this reason, even if the area of the pressure contact surface may slightly vary, the ratio of the change in the total area of the pressure contact surface can be kept low. As a result, the influence due to the area variation of the pressure contact surface is suppressed to a low level, and the stability when holding the optical film is hardly impaired.

  The holding angle of the pressure contact surface of the endless belt with the pressure roller can be adjusted, for example, by changing the position of the guide roller. In addition, the tension of the endless belt can be adjusted by changing the position of the guide roller, whereby the pressure contact force between the endless belt and the pressure roller can be adjusted.

  According to this invention, it becomes possible to stably hold the optical film to be stretched.

  FIG. 1 shows an example of a stretching system to which a pressurizing apparatus of the present invention is applied. The stretching system 10 includes a cleaning unit 12, a swelling unit 14, a dyeing unit 16, a stretching unit 18, a water washing unit 20, and a drying unit 22. Since a known configuration can be applied to portions other than the stretching portion 18 in the stretching system 10, the description thereof is omitted here.

  In this embodiment, a polarizing film made of polyvinyl alcohol (PVA) is used as the optical film 11. In the stretching system 10, the optical film 11 passes through the cleaning unit 12, the swelling unit 14, the dyeing unit 16, the stretching unit 18, the water washing unit 20, and the drying unit 22 in this order, and then the triacetyl cellulose (TAC) film 110 and the like. The protective film is affixed and collected. This invention has a feature in the holding method of the optical film 11 in the extending portion 18, and the feature will be specifically described below.

  FIG. 2 is a diagram showing an outline of the extending portion 18. An optical film pressurizing device 30 is applied to the stretching unit 18. As shown in FIG. 2A, the optical film pressurizing device 30 is attached to the bathtub 32 of the extending portion 18. Specifically, the optical film pressurizing device 30 includes a frame portion 34 configured to be attachable to the bathtub 32 and a belt unit 36 supported by the frame portion 34. The belt unit 36 includes an endless belt 38 made of synthetic resin and a plurality of guide rollers (40, 42, 44, 46, 48, 50, 52) that stretch the endless belt 38. Here, a driving source (driving motor 190 in FIG. 6) is provided on the pressure roller 183 side, and the endless belt 38 is rotated with the rotation of the pressure roller 183. The reason for this is to simplify the configuration of the optical film pressurizing device 30 by not providing a drive source on the optical film pressurizing device 30 side. However, the endless belt 38 may be rotationally driven by providing a drive source on the optical film pressurizing device 30 side. In this embodiment, a synthetic resin (polyurethane) is used for the endless belt 38, but a metal (for example, stainless steel) can be used instead of the synthetic resin. The endless belt 38 is set to have a circumferential length of about 22000 mm, a width of 700 mm, a thickness of 4.0 mm, and a hardness of JIS-A 80 degrees, but is not limited to this setting.

  The optical film pressure device 30 is provided so as to be replaced with a pressure roller 182 shown in FIG. The endless belt 38 of the optical film pressing device 30 is disposed so as to be in pressure contact with the pressing roller 183 via the optical film 11. When the endless belt 38 and the pressure roller 183 are pressed against each other, the optical film 11 to be stretched is held with sufficient strength.

  The configuration of the optical film pressurizing device 30 will be further described with reference to FIG. In FIG. 3, reference numeral 120 indicates the water level of the bathtub. As shown in FIG. 3, the optical film pressurizing device 30 further includes a belt meandering correction mechanism 54, a belt tension adjusting mechanism 56, and a film holding angle adjusting mechanism 58.

  The belt meandering correction mechanism 54 is configured to prevent meandering of the endless belt 38 by adjusting the position of the end of the endless belt 38.

  The belt tension adjusting mechanism 56 supports the guide roller 50 so as to be able to reciprocate. In this embodiment, the guide roller 50 is supported so as to be movable in the horizontal direction, but the movement mode of the guide roller 50 is not limited to this. Further, the tension of the endless belt 38 may be adjusted using a guide roller other than the guide roller 50. The tension adjusting mechanism 56 includes a handle 57 that can be rotated, and displaces the guide roller 50 according to the rotation of the handle 57. The moving range of the guide roller 50 is a range indicated by an arrow 200 in FIG.

  The film holding angle adjusting mechanism 58 supports the guide roller 46 so as to be able to reciprocate. In this embodiment, the guide roller 46 is supported so as to be movable in the vertical direction, but the movement mode of the guide roller 46 is not limited to this. Similar to the tension adjusting mechanism 56 described above, the film holding angle adjusting mechanism 58 includes a handle 59 that can be rotated, and the guide roller 46 is displaced according to the rotation of the handle 59. The moving range of the guide roller 46 is a range indicated by an arrow 300 in FIG.

  The operation of the tension adjusting mechanism 56 and the film holding angle adjusting mechanism 58 will be described with reference to FIG. 4B, the film holding angle adjusting mechanism 58 raises the guide roller 46, so that the holding angle of the pressure contact surface of the endless belt 38 with the pressure roller 183 is changed as shown in FIG. 4C. Can be small. On the other hand, in the state of FIG. 4 (B), the film holding angle adjusting mechanism 58 lowers the guide roller 46, so that the pressure contact surface of the endless belt 38 with the pressure roller 183 as shown in FIG. 4 (D). The holding angle can be increased.

  Further, in the state shown in FIG. 4B, the tension adjusting mechanism 56 moves the guide roller 50 in a direction away from the endless belt 38, whereby the tension of the endless belt 38 can be relaxed. When the tension of the endless belt 38 is increased, the guide roller 50 may be pressed against the endless belt 38 by the tension adjusting mechanism 56.

  According to the above configuration, when the optical film 11 is sandwiched between the endless belt 38 and the pressure roller 183, the area of the pressure contact surface that pressurizes the optical film 11 can be increased. In particular, as shown in FIG. 2B, the area of the pressure contact surface can be increased to about 20 times compared to when the optical film 11 is sandwiched between the rollers 182 and 183. For this reason, even if the area of the pressure contact surface may slightly vary, the ratio of the change in the total area of the pressure contact surface can be kept low. As a result, the influence due to the area variation of the pressure contact surface is suppressed to a low level, and the stability when holding the optical film 11 is not easily lost. Actually, the optical performance of the PVA film was confirmed (stretching in liquid, draw ratio: 615%). As a result, the optical properties were not inferior to the nip roll method, and the film pressure distribution was less varied than the nip roll method.

  Further, as shown in FIG. 5, the tension of the endless belt 38 is adjusted by the tension adjusting mechanism 56, and the holding angle 400 is adjusted by the film holding angle adjusting mechanism 58, so that the endless belt 38 acts on the pressure roller 183. The magnitude of the force N can be adjusted. For this reason, according to the draw ratio of the optical film 11, it becomes possible to adjust the magnitude | size of the force holding the optical film 11 suitably.

  Here, a method for replacing the endless belt 38 will be described with reference to FIG. When exchanging the endless belt 38, the distance piece 60 is removed and the endless belt 38 is stretched around the belt exchanging unit 70, and the guide rollers (40, 42, 44, 46, 48, 50, 52) An endless belt 38 is introduced around the periphery.

  FIG. 7 shows an outline of the stretching system 102 according to the second embodiment. In the stretching system 102, the optical film pressurizing device 30 is applied at a position different from that of the stretching system 10.

  FIG. 8 is a diagram schematically illustrating the extending portion 18 according to the second embodiment. As shown in FIG. 8A, in the second embodiment, an optical film pressing device 30 is provided so as to be in pressure contact with the pressure roller 185. The optical film pressing device 30 is provided so as to be replaced with a roller 184 shown in FIG. The endless belt 38 of the optical film pressing device 30 is disposed so as to be in pressure contact with the pressing roller 185. When the endless belt 38 and the pressure roller 185 are in pressure contact with each other, a holding force necessary for stretching the optical film 11 is generated.

  As described above, the optical film pressurizing device 30 can be arranged at an arbitrary location by changing the mounting position of the optical film pressurizing device 30 with respect to the extending portion 18.

  In the above-described embodiment, an example in which the single optical film pressurizing device 30 is applied to the stretching system 10 or the stretching system 100 has been described. However, a plurality of pressing systems may be applied to the stretching system 10 or the stretching system 100. Is possible. For example, two optical film pressurizing devices 30 can be applied as shown in FIG. 9A, or three optical film pressurizing devices 30 can be applied as shown in FIG. 9B. .

  In the above-described embodiment, the wet stretching method has been described. However, the present invention can also be applied to a stretching system that adopts a dry stretching method.

  The description of the above-described embodiment is an example in all respects and should be considered as not restrictive. The scope of the present invention is shown not by the above embodiments but by the claims. Furthermore, the scope of the present invention is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

It is a figure which shows the example of the extending | stretching system to which an optical film pressurization apparatus is applied. It is a figure which shows the outline of an extending | stretching part. It is a figure which shows the structure of an optical film pressurization apparatus. It is a figure which shows operation | movement of an optical film pressurization apparatus. It is a figure which shows the effect | action of an optical film pressurization apparatus. It is a figure which shows the outline of replacement | exchange of an endless belt. It is a figure which shows the other example of an extending | stretching system. It is a figure which shows the other example of an extending | stretching part. It is a figure which shows the other example of an extending | stretching part.

Explanation of symbols

10-stretching system 18-stretching section 30-optical film pressurizer 34-frame section 36-belt unit 40, 42, 44, 46, 48, 50, 52-guide roller 54-belt meandering correction mechanism 56-belt tension adjustment Mechanism 58-Film holding angle adjustment mechanism

Claims (3)

An optical film pressurizing device configured to press-contact the pressurizing roller configured to contact an optical film to be stretched through the optical film,
A frame portion attachable to the extending portion;
A belt unit supported by the frame portion so as to be in pressure contact with the pressure roller;
With
The belt unit is an optical film pressure device including an endless belt disposed so as to be pressed against the optical pressure roller via the optical film, and a plurality of guide rollers that stretch the endless belt.   A first support portion that movably supports at least one of the plurality of guide rollers; and the endless belt on the pressure contact surface between the endless belt and the pressure roller by moving the first support portion. The optical film pressurizing apparatus according to claim 1, further comprising a holding angle adjusting mechanism having a first adjusting unit configured to adjust a holding angle.   A second support portion movably supporting at least one of the plurality of guide rollers; and a second adjustment configured to adjust the tension of the endless belt by moving the second support portion. The optical film pressurizing apparatus according to claim 1, further comprising a tension adjusting mechanism having a portion.

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