JP2002067058A - Method for manufacturing regular size lens sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a regular size lens sheet capable of cutting a long-sized lens sheet corresponding to a pattern accurately transferred by a lens mold for a long period. SOLUTION: The method for manufacturing the regular size lens sheet comprises the steps of running a distal end of the lens sheet 19 via a cutter 22 while continuing a formation of the long-sized lens sheet 19 in a cylindrical lens mold 7, temporarily stopping the lens sheet 19, and cutting to separate the sheet 19 by a cutter to obtain the regular size lens sheet 20 (A). In this case, a lens sheet slack amount H is changed by a running buffer unit 45 during a running route of the sheet 19. After the cutting, a drive to feed the sheet at a downstream side from the unit 45 of the sheet 19 is accelerated so that the slack amount becomes a predetermined value HD (B). Thereafter, the method also comprises the steps of feeding the distal end of the sheet 19 so that the slack amount maintains the predetermined value HD, stopping the drive to feed the distal end of the sheet when a rotary angle of the mold 7 becomes θO, and starting to cut the sheet by the cutter 22 (C). Thus, when the rotary angle of the mold 7 becomes θC, the cutting is completed (A).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens sheet such as a prism sheet used for improving the front luminance of a backlight or the like used as a surface light source element for illumination in a liquid crystal display device or the like, a projection television, or the like. The present invention relates to a method for manufacturing a lens sheet such as a lenticular lens sheet or a Fresnel lens sheet used for a projection screen used as a display screen of a microfilm reader or the like, and more specifically, requires a continuously formed long lens sheet. The present invention relates to a method of manufacturing a fixed-length lens sheet by cutting each length.

[0002]

2. Description of the Related Art In recent years,
A portable notebook computer with a color liquid crystal display,
In a portable liquid crystal television, a video integrated liquid crystal television, and the like, the large power consumption of the liquid crystal display device is an obstacle to extending the driving time by the battery. Above all, the ratio of the power consumption of the backlight used in the liquid crystal display device to the power consumption of the entire device is large, and keeping the power consumption of the backlight as low as possible extends the driving time of the device by the battery. This is an important issue in increasing the practical value of products. However, if the brightness of the backlight is reduced by suppressing the power consumption of the backlight, the liquid crystal display becomes difficult to see, which is not preferable. Therefore, 3-691
Japanese Patent Publication No. 84-84, etc. discloses a lens sheet in which a large number of lens units such as prism arrays are formed on the surface in order to reduce the power consumption without sacrificing the brightness of the backlight by improving the optical efficiency of the backlight. Is mounted on the light exit surface side of a light guide.

As such a lens sheet, as proposed in JP-A-5-196808 and JP-A-6-59129, from the viewpoint of accurate transfer of a lens pattern and productivity, etc. What formed the lens part using the active energy ray curable composition, such as an ultraviolet curable composition, is used. For example, a lens portion made of a cured product of an active energy ray-curable composition is integrally formed on a transparent substrate such as a transparent resin film or a transparent resin sheet.

On the other hand, in a projection screen such as a projection television or a microfilm reader, a lenticular lens sheet having lenticular lenses formed on both sides is used in order to obtain a good image.
Conventionally, for such a lenticular lens sheet, a method of injection molding or press molding a transparent resin material such as an acrylic resin, a polycarbonate resin, a vinyl chloride resin, and a styrene resin is known.

However, in the injection molding method, it is difficult to form a large-sized lenticular lens sheet, and only a relatively small-sized lenticular lens sheet can be formed. In addition, in the press molding method, since the heating and cooling cycle of the resin plate and the lens mold requires a long time, a large number of lens molds are required for mass production of the lenticular lens sheet, and a large lenticular lens sheet is manufactured. For this, the production equipment is very expensive.

On the other hand, there has been proposed a method of injecting an active energy ray-curable composition into a plate-shaped lens mold and then irradiating the composition with an active energy ray to cure and shape the composition. However, although the method using the active energy ray-curable composition can shorten the molding time and improve the productivity, it has problems such as entrapment of bubbles when the composition is injected into the lens mold. In order to solve this, it is necessary to separately perform defoaming treatment of the composition or adopt a method such as slowly injecting the composition, which is still insufficient for mass production. It was not something. In particular,
Depending on the shape of the lens-type transfer pattern, the bubbles are trapped in the grooves, so that the bubbles are likely to be generated, and the bubbles once generated cannot be easily removed, causing a lens defect due to the bubbles. Was.

As a method for preventing the generation of such bubbles, as described in JP-A-1-192529, after supplying an ultraviolet-curable composition to a lens mold so as to form a composition pool. A method of placing a base film on a composition reservoir, laminating the base film while leveling the composition on a lens mold with a pressure roll through the base film, and irradiating ultraviolet rays to cure, shape, and remove the mold. Has been proposed.

Further, the demand for higher definition of an image is increasing, and in order to respond to this demand, the lenticular lens is required to have a fine pitch.
No. 9627, Japanese Patent Application Laid-Open No. 3-64701, etc.
There has been proposed a method of continuously forming lenticular lenses on both surfaces of a light-transmitting substrate using an ultraviolet-curable composition and a cylindrical lens mold.

As described above, when producing a lens sheet having a fine lens portion using the ultraviolet curable composition, the lens sheet is continuously formed in a long shape.
In some cases, the long lens sheet is once wound up on a roll and stored. In such a case, the innermost part of the sheet is wound near the core (that is, inside the winding). A fold called a winding step is formed on the edge portion of. The influence of the fold extends to, for example, a portion of the long lens sheet having a length of 50 to 60 m, and the optical performance is deteriorated at the fold. Also, since a strong bending force acts on the sheet in the inner portion of the winding, when a portion of a required size in actual use is cut out from this portion, the cut portion is flattened to achieve desired optical performance. I need to correct it.

Therefore, in order to maintain the optical performance of the lens sheet continuously obtained in the form of a long sheet, the long sheet is cut into predetermined lengths and stored in the form of a fixed length sheet. Is preferred.

The cutting into the fixed length sheet is performed by temporarily stopping the leading end of the long sheet running immediately after the sheet is formed, and then cutting the sheet with a cutter. The timing of the cutting is preferably set to be an integral multiple of the length of the lens sheet transferred and formed by the lens mold when the lens mold makes one rotation. This is because, when a partial surface defect such as a scratch is generated in the lens mold, the surface defect in the fixed-length lens sheet formed thereby is present at the same predetermined position for a large number of fixed-length lens sheets. Accordingly, it is possible to perform the patterning for cutting out the lens sheet having the actual size from the fixed-length lens sheet in a certain manner based on the outer edge of the fixed-length lens sheet.

If the transfer pattern area formed on the outer peripheral surface of the cylindrical lens mold has a cut in the circumferential direction (ie, has a seam), the pattern seam formed on the long lens sheet is detected. Thus, the cutting timing can be determined. However, this method cannot be used when the cylindrical lens-type transfer pattern area is a continuous pattern having no seams.

On the other hand, there is a method in which cutting is performed at a predetermined timing in synchronization with, for example, a servomotor for running the long lens sheet so as to correspond to only the running of the long lens sheet. However, in this method, the sliding between the traveling lens system and the long lens sheet is performed between the actual traveling speed or distance of the long lens sheet and the driving speed or the driving distance of the sheet traveling driving system detected by the servomotor. If there is a shift based on the lens, even if the shift is slight each time the shift is accumulated, this shift will be accumulated. Will exist.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and is applicable to a pattern accurately transferred by a lens mold over a long period of time even when a cylindrical lens-shaped transfer pattern area is seamless. It is an object of the present invention to provide a method for manufacturing a fixed-length lens sheet that can cut a long lens sheet by using the method.

[0015]

According to the present invention, there is provided a cylindrical lens mold having an outer peripheral surface on which a lens portion transfer pattern is formed. An active energy ray-curable composition is supplied between the substrate and one surface of the substrate, and the composition is cured and shaped by irradiating the active energy ray through the light-transmitting substrate to form the lens portion transfer pattern. By forming a lens portion made of an active energy ray-curable resin having a shape corresponding to the above, by releasing the lens portion and the light-transmitting substrate integrally from the lens mold, at least the light-transmitting substrate A long lens sheet provided with the lens portion including a repetitive arrangement of lens units is continuously formed on one surface, and the long lens sheet is caused to travel so that the front end portion of the long lens sheet further advances through a cutting position. Required In the method of manufacturing a fixed length lens sheet by cutting every time, the long lens sheet is separated from the lens mold by a travel buffer located on the upper side of the cutting position in the travel path of the long lens sheet. The feed driving of the long lens sheet is performed so that the slack amount becomes a constant value, and the feed driving is stopped based on a synchronization signal generated in synchronization with the rotation of the lens mold, and the lower side of the travel buffer is moved downward. Cut the long lens sheet at the cutting position in a state where the running of the long lens sheet is stopped,
While the running of the long lens sheet is stopped, the slack amount of the long lens sheet is increased in the running buffer section, and after the cutting, the slack amount of the long lens sheet in the running buffer section is constant. A method for manufacturing a fixed-length lens sheet, wherein the speed of the feed drive is increased so as to decrease the value to a value.

In one embodiment of the present invention, the cutting is performed every integer number of rotations of the lens mold. In one embodiment of the present invention, a dancer roll is used in the running buffer to loosen the long lens sheet, and the amount of slack in the long lens sheet is detected by detecting the vertical position of the dancer roll. Is detected. In one aspect of the present invention, a protective film is continuously provided on both surfaces of the long lens sheet at a position before the long lens sheet reaches the travel buffer, and the long film is attached to the long lens. The sheet is cut at the same time as cutting the leading end of the sheet.

In one embodiment of the present invention, the lens portion transfer pattern is formed continuously in the circumferential direction on the outer peripheral surface of the lens mold. In one embodiment of the present invention, the lens-type lens portion transfer pattern is for forming a lens portion including a large number of prism rows or lenticular lens units having a substantially triangular cross section by transfer.

In one embodiment of the present invention, the active energy ray-curable composition is sandwiched between the light-transmitting substrate and the lens mold, and the active energy ray-curable composition is applied to the composition layer. Is irradiated. In one embodiment of the present invention, a nip roll is disposed so as to face the other surface of the light-transmitting substrate before forming the lens portion, and a nip pressure of the nip roll is adjusted by a pressure adjusting mechanism. ,
When forming the lens portion, a relaxation layer made of an active energy ray-curable resin is formed between the lens portion and the translucent substrate. In one embodiment of the present invention, the viscosity of the active energy ray-curable composition supplied between the outer peripheral surface of the lens mold and one surface of the translucent substrate has a viscosity of 20 to 30.
00 mPa · S.

[0019]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram for explaining the outline of the steps of the method for manufacturing a fixed-length lens sheet of the present invention. FIG.
In the above, the long translucent base material 9 unwound from the translucent base roll 9A passes through the cylindrical lens mold 7 along a predetermined traveling path.
, And runs on one side along the outer peripheral surface of the lens mold 7. The active energy ray-curable composition is supplied from the supply nozzle 13 between the lens mold 7 and the light-transmitting substrate 9 to be formed to a required thickness. Then, the active energy ray curable composition is irradiated with the active energy ray emitted from the active energy ray emission light source 14 via the translucent substrate 9. Thus, a long lens sheet 19 in which a lens portion made of an active energy ray-curable resin is formed on one surface of the translucent substrate 9 is formed.

The long lens sheet 19 further travels after being released from the lens mold 7, and protective films 21, 21 'made of, for example, polyethylene or polyethylene-propylene are adhered to both surfaces thereof to such an extent that they can be peeled off. . In this state, the long lens sheet 19 that has reached the cutting position where the cutter 22 is arranged is cut by the cutter 22 in a state where the leading end thereof is further moved a predetermined distance through the cutting position and then temporarily stopped. And separated. Thereafter, while continuing to form the long lens sheet 19 in the same manner, by repeating the procedure of cutting the front end portion of the long lens sheet out of the cutting position by a predetermined distance, the desired length of the long lens sheet 19 with the protective films 21 and 21 'is obtained. A fixed-length lens sheet 20 having dimensions is obtained.

In the traveling path of the long lens sheet 19, the supply of the long lens sheet 19 from the lens mold 7 is continued while the supply of the long lens sheet 19 from the cutting end of the long lens sheet 19 is continued. In order to make it possible to temporarily stop the traveling of the long lens sheet, a travel buffering section is provided which generates slack in the long lens sheet and changes the amount of the slack to buffer the sheet travel. Then, cutting is performed by the cutter 22 in synchronization with the rotation of the lens mold 7,
At the start of this cutting, the long lens sheet 1
9 is controlled so that the slack amount becomes a predetermined value. Details of these will be described later.

FIG. 2 shows a cylindrical lens type (roll type) 7.
FIG. 3 is an explanatory view of the formation of a long lens sheet by using FIG. 3, and FIG. 3 is a perspective view of a lens mold 7 used therein. FIG. 4 is a schematic diagram showing details of a step of obtaining a fixed length lens sheet 20 from the long lens sheet 19 by cutting. FIG.
FIG. 1 is a schematic cross-sectional view illustrating an example of a fixed length lens sheet 20 manufactured according to the present invention.

First, the fixed length lens sheet 20 will be described with reference to FIG. Here, illustration and description of the protective films 21 and 21 ′ provided on both sides in a releasable manner are omitted. The fixed length lens sheet 20 shown in FIG. 5 is a surface light source element such as a backlight of a portable notebook personal computer equipped with a color liquid crystal display device or a liquid crystal display device such as a portable liquid crystal television or a video integrated liquid crystal television. 1 shows a prism sheet used to improve the front luminance of the lens, and this prism sheet corresponds to the lens sheet in the present invention. As shown in FIG. 5, in the lens sheet 20, a large number of lens units are formed on one surface of the light-transmitting substrate 2 (formed by cutting the long light-transmitting substrate 9). A lens portion 3 composed of (prism rows) is formed of an active energy ray-curable resin, and a relaxation layer 1 is interposed between the light transmitting base material 2 and the lens portion 3.

The relaxation layer 1 is integrally formed of the same active energy ray curable resin as the lens portion 3. This relaxation layer 1
Is formed to a thickness of 1 to 30% of the lens height (H) of the lens portion 3, whereby the occurrence of a spot-like pattern due to polymerization shrinkage during curing of the active energy ray-curable composition can be suppressed. it can.

In the present invention, the surface shape of the lens portion 3 of the lens sheet 20 may be changed according to the purpose, in addition to the prism surface in which a large number of prism rows are formed parallel to each other as shown in FIG. The shape may be a lenticular lens surface or a wavy lens surface in which a large number of lenticular lenses having a semicircular or semielliptical shape are formed in parallel with each other.

Further, a lens portion comprising a large number of lens units can be formed on the other surface of the lens sheet of FIG. 5 to form a double-sided lens sheet. In FIG. 6 showing an example of such a double-sided lens sheet 30, a lens portion 4 composed of a large number of lens units (prism rows) is also formed on the other surface of the translucent substrate 2 by an active energy ray-curable resin.
The relaxation layer 1 ′ is interposed between the light-transmitting substrate 2 and the lens unit 4. The lens portions 3 and 4 are made of a transparent base material 2
The same type and size of lens shape may be formed on both surfaces, or different types and sizes of lens shapes may be formed. In the lens sheet of the present invention, the thickness of the lens portions 3 and 4 is preferably about 10 to 150 μm, and the pitch of the lens unit is preferably about 10 to 150 μm. In particular, in the present invention in which a lens portion is formed of an active energy ray-curable resin, the present invention is suitable for a fine-pitch lens sheet used for a surface light source element capable of responding to high definition such as a liquid crystal display device. Is preferably in the range of 10 to 100 μm, and more preferably in the range of 10 to 50 μm.

Further, when the lens unit is a prism array, the apex angle of the prism array is preferably in the range of 50 to 160 °. In general, a light source, a light guide having one side facing the light source as a light incident surface, and a light exit surface having one surface substantially perpendicular to the light incident surface, and disposed on a light exit surface of the light guide. In a surface light source element (edge light type) for a liquid crystal display device which is basically composed of a prism sheet, the prism sheet 20 is arranged such that the prism surface is on the liquid crystal panel side.
Are arranged, the apex angle of the prism array is 80 to 100.
範 囲, preferably in the range of 85 to 95 ゜. On the other hand, when the prism sheet 20 is arranged so that the prism surface is on the light guide side, the apex angle of the prism row is in a range of about 50 to 75 °, preferably 55 to 70 °.
範 囲 range. The lens portions 3 and 4 made of the active energy ray-curable resin are used to improve the brightness of the surface light source element.
Those having a relatively high refractive index are preferred, and specifically, the refractive index is preferably 1.50 or more.
In particular, when the prism sheet 20 is arranged such that the prism surface is on the liquid crystal panel side as in the former case, the refractive index is preferably 1.55 or more, more preferably 1.6 or more.

In the lens sheets 20 and 30 of the present invention, the relaxation layers 1 and 1 'have a lens height of 1 to 30 as described above.
% Is preferable. In the present invention, the lens height is the height (H, H ′) of the lens portions 3 and 4 as shown in FIGS. 5 and 6, and the relaxation layers 1 and 1 ′ are made of an active energy ray-curable resin. When formed integrally with the lens portion, the thickness refers to the thickness of the active energy ray-curable resin excluding the thickness of the relaxing layers 1 and 1 ′. The relief layers 1 and 1 ′ form the lens shape (surface shape of the lens portion) by supplementing the lack of resin in the lens mold due to polymerization shrinkage of the active energy ray-curable resin when forming the lens portions 3 and 4. When the thickness of the relaxing layers 1 and 1 'is less than 1% of the lens height, the effect of relaxing the deformation of the lens shape due to polymerization shrinkage in the relaxing layers 1 and 1' is reduced. Tends to be insufficient, and conversely, the lens height of 3
If it exceeds 0%, it becomes difficult to control the suppression of unevenness in the thickness of the relaxing layers 1 and 1 ′, and the optical characteristics tend to decrease due to unevenness in thickness (unevenness). The thickness of the relaxing layers 1, 1 'is preferably in the range of 1 to 25% of the lens height, and more preferably in the range of 3 to 15%. When forming a fine lens unit having a pitch or thickness of about several tens of μm, such as a prism sheet for a surface light source element of a liquid crystal display device as shown in FIGS. 1 ′ is preferably thin, for example, preferably in the range of about 1 to 10 μm, and more preferably in the range of 1 to 5 μm.
Further, in the double-sided lenticular lens sheet, for example, the thickness of the relaxation layers 1 and 1 ′ is preferably in the range of about 5 to 30 μm, and more preferably in the range of 5 to 15 μm.

The light-transmitting substrate 2 constituting the lens sheet is not particularly limited as long as it is a material that transmits active energy rays such as ultraviolet rays and electron beams. Polyester resins, acrylic resins, polycarbonate resins And a sheet or film of a transparent resin such as a vinyl chloride resin or a polymethacrylimide resin. In particular, polymethyl methacrylate having a lower refractive index than the refractive index of the lens parts 3 and 4 and having a low surface reflectance, a mixture of polymethyl acrylate and polyvinylidene fluoride resin, a polycarbonate resin,
Those made of a polyester resin such as polyethylene terephthalate are preferred. The thickness of the light-transmitting substrate 2 varies depending on the use of the lens sheet.
Those having a range of about μm are used. The light-transmissive substrate 2 includes a relaxation layer 1 made of an active energy ray-curable resin,
In order to improve the adhesion with 1 ′, it is preferable that the surface is subjected to an adhesion improving treatment such as an anchor coating treatment.

The active energy ray-curable resin forming the relaxation layers 1 and 1 'of the lens sheet and the lens portions 3 and 4 is not particularly limited as long as it is cured with an active energy ray such as an ultraviolet ray or an electron beam. Not something, for example
Examples include polyesters, epoxy resins, (meth) acrylate resins such as polyester (meth) acrylate, epoxy (meth) acrylate, and urethane (meth) acrylate. Among them, (meth) acrylate resins are particularly preferable from the viewpoint of their optical characteristics and the like. As the active energy ray-curable composition used for such a cured resin, polyhydric acrylate and / or polyhydric methacrylate (hereinafter, referred to as polyhydric (meth) acrylate) in terms of handleability, curability, and the like. , Monoacrylate and / or monomethacrylate (hereinafter, referred to as mono (meth) acrylate), and a photopolymerization initiator using active energy rays as a main component are preferable. Representative polyvalent (meth) acrylates include polyol poly (meth) acrylate, polyester poly (meth) acrylate, epoxy poly (meth) acrylate, urethane poly (meth) acrylate, and the like. These are used alone or as a mixture of two or more. Also,
Examples of the mono (meth) acrylate include a mono (meth) acrylate of a monoalcohol and a mono (meth) acrylate of a polyol. In the latter case, when a metal type is used, a hydroxyl group is used. In order to reduce the difficulty of demolding from the metal mold that seems to be the effect,
It is better to use it in small quantities. When a metal type is used, it is preferable to use a small amount of (meth) acrylic acid and its metal salt because they have high polarity.

In the cylindrical lens mold 7 shown in FIGS. 2 and 3, a large number of lens unit transfer portions corresponding to a large number of lens units of the lens sheet are formed on the outer peripheral surface of the cylindrical roll 16. It has a lens portion transfer pattern 18.
The lens mold 7 has a lens unit transfer portion made of a metal such as aluminum, brass, steel, or a synthetic resin such as a silicone resin, a polyurethane resin, an epoxy resin, an ABS resin, a fluorine resin, and a polymethylpentene resin. And
Those manufactured by Ni electroforming are used. From the viewpoint of heat resistance, strength, and the like, it is desirable to use a lens unit transfer portion or the like made of metal. In the present invention, as the cylindrical lens mold 7, a thin lens mold on which a lens portion transfer pattern is formed may be used by being wound around the outer peripheral surface of a cylindrical roll and fixed. In addition, the relaxation layer 1
In order to more uniformly form the lens, it is preferable to use a stepped lens mold in which a thick step is formed at both ends of the outer peripheral surface of the cylindrical lens mold 7 whose radial height is higher than the central part. . It is preferable to apply a plating of nickel, chromium or the like to the surface of such a lens mold in order to prevent various types of corrosion.

The lens mold 7 is supplied with a long translucent base material 9 (cut to form the translucent base material 2 of each fixed-length lens sheet 20) along the lens portion transfer pattern surface. The active energy ray-curable composition 10 is continuously supplied from the resin tank 12 through the supply nozzle 13 between the lens mold 7 and the translucent substrate 9. A nip roll 8 is provided outside the light-transmitting substrate 9 (on the side opposite to the lens mold 7 side) to make the supplied active energy ray-curable composition 10 uniform in thickness. As the nip roll 8, a metal roll, a rubber roll, or the like is used.
Further, in order to make the thickness of the active energy ray-curable composition 10 uniform, it is preferable that the nip roll 8 is processed with high accuracy in terms of roundness, surface roughness, and the like. In the case of a rubber roll, A rubber having a high hardness of 60 degrees or more is preferable. The nip roll 8 needs to accurately adjust the thickness of the active energy ray-curable composition 10, and the pressure adjustment mechanism 11 performs a pressure application operation. As the pressure adjusting mechanism 11, a hydraulic cylinder, a pneumatic cylinder, various screw mechanisms and the like can be used, but a pneumatic cylinder is preferable from the viewpoint of simplicity of the mechanism. The air pressure is controlled by a pressure regulating valve or the like.

The active energy ray-curable composition 10 supplied between the lens mold 7 and the translucent substrate 9 may be maintained at a constant viscosity in order to form the relaxation layer 1 to a constant thickness. preferable. Although the viscosity range varies depending on the thickness of the relaxation layer 1 to be formed, it is generally preferable to set the viscosity in the range of 20 to 3000 mPa · S under the temperature conditions (for example, 40 ° C.) at the time of production, and more preferably. Is 100-100
The range is 0 mPa · S. When the viscosity of the active energy ray-curable composition 10 is less than 20 mPa · S, it is necessary to set the nip pressure extremely low or to extremely increase the molding speed for forming the relaxation layer 1. .
However, when the nip pressure is extremely reduced, the pressure adjusting mechanism 11
Tends to be unable to operate stably, and the unevenness of the thickness of the relaxing layer 1 tends to be caused. Further, when the molding speed is extremely increased, the irradiation amount of the active energy ray is insufficient, and the curing of the active energy ray-curable composition 10 tends to be insufficient. On the other hand, when the viscosity of the active energy ray-curable composition 10 exceeds 3000 mPa · S, the active energy ray-curable composition 10 does not sufficiently spread to the details of the lens-shaped lens portion transfer pattern, and the lens shape is accurately transferred. This tends to be difficult, defects tend to occur due to the incorporation of bubbles, and productivity tends to deteriorate due to an extremely low molding speed. In order to maintain the viscosity of the active energy ray-curable composition 10 at a constant level in this manner, a sheath heater, hot water, or the like is provided outside or inside the resin tank 12 so that the temperature of the active energy ray-curable composition 10 can be controlled. It is preferable to install heat source equipment such as a jacket.

After the active energy ray-curable composition 10 is supplied between the lens mold 7 and the translucent substrate 9, the active energy ray-curable composition 10 is added to the lens mold 7 and the translucent substrate 9. The active energy ray emission light source 14 is sandwiched between
Irradiates an active energy ray through the light-transmitting substrate 9 to polymerize and cure the active energy ray-curable composition 10,
The transfer of the lens portion transfer pattern formed on the lens mold 7 is performed. As the active energy ray irradiation device 14, a chemical lamp for chemical reaction, a low-pressure mercury lamp, a high-pressure mercury lamp, a metal halide lamp, a visible light halogen lamp, or the like is used. The irradiation amount of the active energy ray is 20
The integrated energy at a wavelength of 0 to 600 nm is 0.01 to 5
It is preferable that the concentration be 0 J / cm ² . Also,
The irradiation atmosphere of the active energy ray may be air or an inert gas atmosphere such as nitrogen or argon. Next, the lens sheet in which the light-transmitting substrate 9 and the lens portion formed of the polymerized and cured active energy ray-curable resin are integrated is released from the lens mold 7.

FIG. 7 is an explanatory view of forming a long lens sheet for manufacturing the double-sided lens sheet 30 as shown in FIG. 6, and is basically a light-transmitting substrate as shown in FIG. A first step S1 of forming a lens portion on the material 9 on the first surface and a second step S2 of forming a lens portion on the second surface are sequentially performed. That is, the first step S1 is the same as FIG.
In the second step S2, a long sheet 19 having a prism portion formed on the first surface in the first step S1 is used as a light-transmitting base material, and a lens mold 7 'having a required lens portion transfer pattern is used. Except for this, it is the same as the first stage S1. In the second step S2, parts or members similar to the parts or members in the first step S1 are designated by the same reference numerals with the addition of “′”. The long double-sided lens sheet 29 is formed through the second step S2, and the fixed double-sided lens sheet 3 is cut by cutting the long double-sided lens sheet 29.
0 is obtained.

As shown in FIG. 2, the double-sided lens sheet 30 manufactured as described above has lens portions 3 disposed on both sides of the light-transmitting substrate 2 via the relaxation layers 1 and 1 ′, respectively. , 4, a large number of prism rows each having a substantially triangular cross section are arranged in parallel, and the apex angle of the prism row formed on one lens unit 3 is in the range of 50 ° to 75 °. It is preferable that the apex angle of the prism array formed on the other lens portion 4 be in the range of 110 ° to 160 °.

Next, a process of manufacturing the fixed-length lens sheet 20 by cutting from the long-length lens sheet 19 will be described with reference to FIG. In addition, also in this case, illustration and description of the protective films 21 and 21 ′ that are provided on both sides in a releasable manner are omitted as appropriate. The process of manufacturing the fixed-size double-sided lens sheet 30 by cutting the long double-sided lens sheet 29 can be performed in the same manner.

In FIG. 4, the long lens sheet 19 released from the lens mold 7 rotating at a constant angular velocity travels along a predetermined traveling path and reaches a pair of take-off rollers 41. The travel of the lens sheet 19 to the take-up roller 41 is performed at a constant speed by driving by a torque motor connected to the take-up roller 41. This torque motor is controlled by a controller 42, which
43. An ink jet printer 44 is disposed in the traveling path to the take-off roller 41, and the printer applies a protective film 21 and 21 'to each part of the long lens sheet 19 which is cut into a fixed length lens sheet. Record the product number and production lot number.

The lens sheet 19 is further moved from the take-up roller 41 via the running buffer 45 to the pair of intermittent feed rollers 4.
To 6. The running buffer 45 changes the amount of slack of the long lens sheet 19 by using the dancer roll 45 a, so that the intermittent feed roller 46 supplies the long lens sheet 19 at a constant speed from the take-up roller 41. This is a traveling buffer mechanism for enabling intermittent traveling of the long lens sheet 19. That is, when there is a difference between the traveling speed at the position of the take-up roller 41 and the traveling speed at the position of the intermittent feed roller 46, the dancer roll 45a moves in the vertical direction. A pulse motor is connected to the intermittent feed roller 46, and the pulse motor
7, and the controller is controlled by the CPU 43. The controller 47 is provided with a counter 48 for counting the number of driving pulses for the pulse motor, and a detection signal of the counter is input to the CPU 43. The number of drive pulses detected by the counter 48 corresponds to the amount by which the front end of the long lens sheet 19 is fed by the intermittent feed roller 46.

The travel buffer 45 has an optical displacement sensor 4 for detecting the vertical position of the dancer roll 45a.
9 are arranged. The signal of the vertical position of the dancer roll 45a detected by the optical displacement sensor 49 is CP
It is input to U43.

The long lens sheet 19 further advances from the intermittent feed roller 46 to a cutting position where the cutter 22 is arranged. An optical sensor 53 is disposed between the intermittent feed roller 46 and the cutting position, and the optical sensor reads a product number, a production lot number, and the like recorded on the protective films 21 and 21 ′ of the lens sheet 19, and The signal is input to the CPU 43 and used when creating product data.

On the other hand, a lens mold 7 rotating at a constant angular velocity
Is provided with a sensor 55 for detecting its rotation cycle. This sensor outputs a signal (synchronization signal) every time the lens mold 7 makes one rotation.
Can be used. The detection signal by the rotation cycle detection sensor 55 is a CPU
43 is input.

Next, the feed driving of the intermittent feed roller 46 and the control of cutting the lens sheet by the cutter 22 based on the command of the CPU 43 will be described with reference to FIG. FIG.
, The rotation angle (phase) of the lens mold 7 is indicated by θ, and the vertical position of the dancer roll 45a corresponding to the slack amount of the long lens sheet 19 in the travel buffer 45 is indicated by H, The distance that the leading end of the long lens sheet 19 advances from the cutting position is indicated by P. A force is constantly applied to the dancer roll 45a downward in the figure by a spring or the like.

FIG. 8A shows a state in which the end of the long lens sheet 19 is cut by the cutter 22 to form one fixed lens sheet 20. Here, the rotation angle θ of the lens mold 7 is θ _C , and the vertical position H of the dancer roll 45a is H _C. In this state, the driving of the intermittent feed roller 46 not shown in FIG. 8 is stopped, and the running of the long lens sheet 19 on the lower side of the running buffer 45 is stopped.

FIG. 8B shows a state after the state shown in FIG.
Move the dancer roll 45a to the predetermined position H _D Intermittent as
Driving the feed roller 46, the leading end of the long lens sheet 19
This shows a state in which a copy has been sent. Here, the lens type 7
Rotation angle θ is θ_D And a long length from the position of the cutter 22
The advance distance P of the front end of the lens sheet 19 is P_D It is.
The dancer roll 45a is moved from the position of FIG.
In order to raise quickly to the position (B), the travel buffer
The running speed of the long lens sheet 19 on the lower side of 45 runs
Travel of the long lens sheet 19 on the upper side of the row buffer 45
Increase the speed of the intermittent feed roller 46 so that it becomes larger than the speed.
Let The speed increase of the intermittent feed roller 46 is shown in FIG.
Dancer detected by an optical displacement sensor 49 that is not
The vertical position H of the roll 45a is the predetermined position H_D Below
Is controlled by a servomotor based on
You.

[0047] After the dancer roll 45a reaches a predetermined position H _D is to maintain the vertical position of dancer roll 45a is detected by the optical displacement sensor 49 always place H _D, the driving of the intermittent feed rollers 46 Controlled by servo motor. At this time, the speed of the outer periphery of the lens mold 7 and the speed of the leading end of the long lens sheet 19 match. This state is maintained until the next mold synchronization signal is obtained, and the formation of the long lens sheet 19 and the advance of the leading end thereof are continued. The rotation speed of the intermittent feed roller 46 during driving is controlled only by the position of the dancer roll 45a, and is independent of the rotation speed of the lens mold 7. However, even if the signal is obtained from the rotation speed of the lens mold 7 or other driving force, the present invention is not limited to the present invention as long as it controls the running of the long lens sheet based on the slack amount of the long lens sheet. Will be included.

FIG. 8C shows the state after the state shown in FIG.
This shows a state where the lens mold 7 continues to rotate and the rotation angle θ has reached a predetermined value θ ₀ . Here, the vertical position H of the dancer roll 45a is H _D , as in FIG. 8B, except that the forward distance P of the leading end of the long lens sheet 19 from the position of the cutter 22 is P ₀ (P ₀ > P _D ). A mold synchronization signal is generated at the rotation angle θ ₀ . Based on this synchronization signal, a stop signal is issued to the intermittent feed roller 46 to stop the feed drive. Thus, the cutting of the long lens sheet 19 by the cutter 22 is started in a state where the running of the long lens sheet 19 on the lower side of the running buffer 45 is stopped.

After that, the running of the long lens sheet 19 on the upper side of the running buffer 45 is continued, so that the slack amount of the long lens sheet 19 in the running buffer 45 gradually increases. That is, while the cutting operation by the cutter 22 is continued, the lens mold 7 is rotating at a constant angular velocity, the forming of the long lens sheet 19 is continuously performed, and the long lens sheet 19 formed during the cutting operation is It is stored as the amount of slack caused by the lowering of the dancer roll 45a of the travel buffer 45, and eventually the state of FIG. 8A is reached.

As described above, FIGS.
By repeating the operation of (C), the fixed-length lens sheet 2
0 is produced.

The control of the feed driving of the intermittent feed roller 46 by the CPU 43 and the control of the cutting of the long lens sheet 19 by the cutter 22 are not particularly limited to the above-described embodiment. What is necessary is to cut the long lens sheet 19 at a predetermined timing synchronized with the rotation of the lens type while keeping it constant.

In the production of the fixed-size double-sided lens sheet 30, the same method is applied by using the long double-sided lens sheet 29 shown in FIG. 7 instead of the long single-sided lens sheet 19 in FIG. Processing may be performed. The cutting of the lens sheet may be performed every one rotation of the lens mold 7, or may be performed every two or more rotations.

As described above, in the present embodiment, the feeding error of the leading end of the long lens sheet does not accumulate every time the cutting is performed. The arrangement is always the same in synchronization with the rotation of the mold.

FIG. 9 is a plan view showing the fixed-length lens sheet 20 obtained as described above. The illustrated fixed-length lens sheet shows an example in which the cutting is performed every two rotations of the lens mold 7, and the first region 20a is formed by the first rotation of the lens mold 7, and the second rotation is performed. The second region 20b is formed by the above rotation. When a defect such as a scratch is generated on the surface of the lens mold 7 by repeating the production of the fixed-length lens sheet, a defect DF is generated in the fixed-length lens sheet 20 at a position corresponding to each of the regions 20a and 20b. . In such a case, a similar defect exists at the same location in a fixed-length lens sheet manufactured thereafter. Accordingly, from the fixed-length lens sheet, sheets 20-1, 20-2, 20- having dimensions used in an actual product (for example, a backlight of a liquid crystal display device).
When cutting out No. 3, these defects can be avoided by performing the same cutting out.

Further, when the defect DF is minor, the defect is avoided when cutting out an application requiring high optical performance, and when extracting a defect not requiring high precision, the defect is avoided. By performing the cutout including the portion, the fixed-length lens sheet can be effectively used.

In the present embodiment, since such a use form is possible, even if a defect occurs on the outer peripheral surface of the lens mold 7 where the lens portion transfer pattern is formed, the defect is determined using the lens mold 7. It is possible to continue the manufacture of the length lens sheet, and the life of the lens mold 7 can be prolonged.

[0057]

As described above, according to the present invention, the slack amount of the long lens sheet is detected, and the running state of the long lens sheet is maintained so that the slack amount is constant. By cutting the long lens sheet based on the synchronization signal issued in synchronization with the rotation of the lens, the feeding error of the front end of the long lens sheet does not accumulate every time the cutting is performed. Even if the transfer pattern area of the lens mold is seamless, the long lens sheet can be cut accurately in accordance with the pattern transferred by the lens mold over a long period of time, and a large number of fixed-length lens sheets obtained thereby In the above, the lens unit patterns are always arranged in the same manner, and no pattern shift occurs.

[Brief description of the drawings]

FIG. 1 is a schematic view for explaining an outline of steps of a method for manufacturing a fixed length lens sheet of the present invention.

FIG. 2 is an explanatory view of forming a long lens sheet using a cylindrical lens mold.

FIG. 3 is a perspective view of a lens mold used for forming a long lens sheet.

FIG. 4 is a schematic view showing details of a step of obtaining a fixed length lens sheet by cutting a long lens sheet.

FIG. 5 is a schematic cross-sectional view showing an example of a fixed-size single-sided lens sheet manufactured according to the present invention.

FIG. 6 is a schematic sectional view showing an example of a fixed-size double-sided lens sheet manufactured according to the present invention.

FIG. 7 is an explanatory diagram of forming a long lens sheet for manufacturing a double-sided lens sheet.

FIG. 8 is an explanatory diagram of feed driving of an intermittent feed roller and control of lens sheet cutting by a cutter.

FIG. 9 is a plan view of a fixed-length lens sheet.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1, 1 'Relaxation layer 2 Translucent base material 3, 4 Lens part 7 Cylindrical lens type 8 Nip roll 9 Long translucent base material 9A Translucent base material roll 10 Active energy ray curable composition 11 Pressure regulation Mechanism 13 Supply nozzle 14 Active energy ray emission light source 16 Cylindrical roll 18 Lens portion transfer pattern 19 Long single-sided lens sheet 20 Fixed single-sided lens sheet 20a, 20b Transfer area of fixed-size lens sheet 20-1, 20-2, 20 -3 Cut-out area from fixed-size lens sheet 21, 21 'Protective film 22 Cutter 29 Long double-sided lens sheet 30 Fixed-size double-sided lens sheet 41 Pick-up roller 42 Controller 43 CPU 44 Ink-jet printer 45 Running buffer 45a Dancer roll 46 Intermittent feed Roller 47 controller 48 counter 49 light Advancing distance DF defects vertical position P long lens sheet leading end of the rotary angle H dancer roll position sensor 53 light sensor 55 rotation cycle detecting sensor θ lens type

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Makoto Okawa 20-1 Miyukicho, Otake City, Hiroshima Prefecture Inside Mitsubishi Rayon Co., Ltd. Central Research Laboratory (72) Inventor Muneo Yoneda 20-1 Miyukicho, Otake City, Hiroshima Prefecture No. Mitsubishi Rayon Co., Ltd. Central Research Laboratory (72) Inventor Yoshinobu Shiraishi 6-27-5 Saine, Kashiwa-shi, Chiba F-term (reference) 4F202 AA15 AA16 AA21 AA24 AA28 AA40 AH75 CA01 CA04 CB02 CB11 CB22 CD05 CD12 CN30 4F204 AA15 AA16 AA21 AA24 AA28 AA40 AH75 EA03 EB02 EB11 EB22 EB24 EF01 EF27 EF49 EK03 EK17 EK18 EK24 EL19 EW02 EW23 EW34

Claims (9)

[Claims] An active energy ray-curable composition is supplied between the outer peripheral surface of a cylindrical lens mold having an outer peripheral surface on which a lens portion transfer pattern is formed and one surface of a light-transmitting substrate. Irradiating active energy rays through the translucent base material to cure and shape the composition to form a lens portion made of an active energy ray-cured resin having a shape corresponding to the lens portion transfer pattern, By releasing the lens portion and the transparent substrate from the lens mold integrally,
A long lens sheet provided with the lens portion including a repetitive arrangement of lens units is continuously formed on at least one surface of the light-transmitting base material, and the cutting end position of the long lens sheet is set at the cutting position. In the method of manufacturing a fixed-length lens sheet by cutting to a required length by further traveling so as to further advance, a position on the upper side of the cutting position in the running path of the long lens sheet released from the lens mold The driving of the long lens sheet is performed so that the slack amount of the long lens sheet becomes a constant value in the running buffer unit, and the driving of the long lens sheet is performed based on a synchronization signal generated in synchronization with the rotation of the lens mold. The cutting of the long lens sheet is performed at the cutting position in a state where the running of the long lens sheet on the lower side from the running buffer is stopped, and the running of the long lens sheet is stopped. The running buffer increases the slack amount of the long lens sheet, and after the cutting is completed, the feed drive is performed so that the slack amount of the long lens sheet in the running buffer decreases to the constant value. Characterized by increasing speed,
Manufacturing method of fixed-length lens sheet. 2. The method according to claim 1, wherein the cutting is performed for every integral number of rotations of the lens mold. 3. A looseness of the long lens sheet is detected by detecting a vertical position of the dancer roll by using a dancer roll in the running buffer to loosen the long lens sheet. Characterized by the fact that
A method for manufacturing the fixed-length lens sheet according to claim 1. 4. A protective film is continuously provided on both surfaces of the long lens sheet at a position before the long lens sheet reaches the travel buffer, and the protective film is attached to the front end of the long lens sheet. The method for producing a fixed-length lens sheet according to any one of claims 1 to 3, wherein the cutting is performed at the same time when the part is cut. 5. The fixed length lens sheet according to claim 1, wherein the lens portion transfer pattern is formed continuously on an outer peripheral surface of the lens mold in a circumferential direction. Production method. 6. The lens-type lens portion transfer pattern is for forming a lens portion including a large number of prism rows or lenticular lens units having a substantially triangular cross section by transfer. Claim 1
5. The method for producing a fixed length lens sheet according to any one of 5. 7. In a state where the active energy ray-curable composition is sandwiched between the translucent substrate and the lens mold,
The method according to any one of claims 1 to 6, wherein the composition is irradiated with an active energy ray. 8. The method according to claim 1, wherein a nip roll is disposed so as to face the other surface of the light-transmitting substrate before forming the lens portion, and a nip pressure of the nip roll is adjusted by a pressure adjusting mechanism. The method according to any one of claims 1 to 7, wherein a relief layer made of an active energy ray-curable resin is formed between the lens portion and the light-transmitting substrate when forming the portion. A method for manufacturing a shading lens sheet. 9. The active energy ray-curable composition supplied between the outer peripheral surface of the lens mold and one surface of the translucent substrate has a viscosity of 20 to 3000 mPa · S. The method for producing a fixed length lens sheet according to claim 1.