JP5471494B2 - Optical element sheet continuous double-sided forming method and optical element sheet forming apparatus - Google Patents

Description

  The present invention relates to a method for continuously forming both sides of an optical element sheet, in which a plurality of optical elements are successively formed on the front surface and the back surface of a base film, and the optical element sheet forming apparatus.

  The optical element in the present invention includes a lens, a prism, a mirror element, a diffraction element, a diffraction mirror, a grism, a Fresnel lens, a lenticular sheet, a lens sheet, a microlens array, and the like. Includes black ink. In the present invention, a plurality of these optical elements are formed on both sides of the base film, and the formed product is called an optical element sheet. The optical elements formed on the front surface and the back surface of the base film need not be the same type of optical elements. For example, a lens may be formed on one surface and a diaphragm formed on the other surface.

  Optical elements such as lenses are formed in a matrix on an optical element sheet, and are separated after completion and used as individual optical elements. On the other hand, lenticular sheets and the like are not individually separated on the optical element sheet, but are used after being cut into a predetermined size after completion. It is included.

  The present invention sequentially forms a plurality of such optical elements on both sides of the base film. Here, the optical element forming method includes “molding”, “molding”, and “printing”. Collectively called “formation”. “Molding” refers to a process in which a solid workpiece is softened by heating or pressurization and is brought into close contact with the transfer surface of the mold to transfer it. “Molding” is a process in which a liquid workpiece is placed in the mold. It is a process in which it is poured into a film, cured by heating or UV light irradiation, and transferred. “Printing” refers to a process in which a printing material (ink) is attached to a roll-shaped plate and the printing material is transferred to a base film.

  Such an optical element sheet forming method can form a large number of optical elements continuously, and in recent years, a strobe lens for a mobile phone or a digital camera, a diffusion lens for LED illumination, or a lens sheet for a backlight of a liquid crystal display device. It has come to be used for forming various optical elements.

  As a method for forming an optical element sheet, Patent Document 1 discloses that a lens sheet, in particular, a prism sheet, a lenticular lens sheet, and a Fresnel lens sheet are continuously formed on one side of a base film by transferring an energy ray curable resin using a roll die. In particular, a method for forming the lens sheet is proposed, which eliminates the warp of the lens sheet by temperature control before and during curing.

  In Patent Document 2, an ultraviolet curable resin is applied to one surface of a base film, and this is introduced between a roll mold for forming a lenticular lens array and a pressure roll, pressurized, cured by ultraviolet irradiation, and lenticular. After forming a lens array, a second ultraviolet curable resin is applied to the other surface of the base film, and this is introduced between a roll mold for forming a convex portion and a pressure roll, and pressurized. It discloses a method of forming a transmissive rear screen by forming a convex part by curing by irradiation and applying a light-shielding ink to the top surface of the convex part.

  Further, Patent Document 2 provides an alignment mark forming mold portion in a blank portion of a lenticular lens array forming roll mold to form an alignment mark at the same time as forming the lenticular lens array, while a convex portion forming roll. Alignment of optical elements formed on both sides of the sheet by forming the same alignment mark on the mold and aligning the marks on the convex mold roll mold with the alignment marks formed on the resin layer We are proposing a technology to do this.

JP 2009-292060 A JP 2007-264184 A

  Since the alignment technique of Patent Document 2 has not been specifically described, it is not clear, but the alignment mark of the convex mold forming roll mold matches the alignment mark formed on the resin layer. It is considered that the rotational phase of the convex part forming roll mold is adjusted, and this adjustment is considered to be performed in the initial stage of formation.

  However, when performing optical element formation on the other side following optical element formation on one side of the base film, if there is a temperature change in the base film between these two steps, expansion and contraction in the length direction occurs. Vertical misalignment occurs when the optical element on the other side is formed. Since the optical element is formed on the base film by continuously conveying the base film, the length change of the base film is accumulated, and if left as it is, a very large value is obtained.

  For example, when the sheet material is polyethylene terephthalate (PET), the linear expansion coefficient is about 70 ppm / ° C., but if the temperature changes by 1 ° C. during transfer formation between one side and the other side, the length is 70 μm per meter. It becomes a change. In addition, when 100 m is fed in this state, the accumulated length changes to 7 mm, and the optical elements on the one surface and the other surface are misaligned and cannot be used.

  When the sheet material is non-alkali glass with a thickness of about 100 μm, the amount of vertical misalignment is 300 μm when it is fed under the same conditions, although the linear expansion coefficient is as small as about 3 ppm / ° C. It is not an acceptable value.

  In view of such problems, the present invention provides an optical element formed on the front and back surfaces when forming a plurality of optical elements by an optical element forming step on the surface of the base film and a subsequent optical element forming step on the back surface. It is an object of the present invention to provide an optical element sheet continuous surface forming method and an optical element sheet forming apparatus capable of forming an optical element having no decentration between the front and back by reliably correcting the deviation.

  The above object is achieved by the following method.

1. A first optical element forming step of forming, molding or printing a plurality of optical elements and alignment marks on one side of the base film using a roll mold;
Continuously performing a second optical element forming step of forming, molding or printing a plurality of optical elements on the other side of the base film using a roll mold,
The alignment mark is detected between the first optical element formation step and the second optical element formation step, and the rotational speed of the roll mold in the second optical element formation step based on the detection result, or A method for continuously forming both sides of an optical element sheet, wherein the conveyance speed of the optical element sheet is sequentially corrected.

  2. 2. The first optical element forming step or the second optical element forming step is performed by supplying an ultraviolet curable resin to the roll mold and curing the resin with ultraviolet rays. A method for continuously forming both sides of an optical element sheet.

  3. 3. The method for continuously forming both sides of an optical element sheet according to 1 or 2, wherein the correction of the speed in the second optical element forming step is performed every time the mark of the roll mold is detected.

4 . A base film supply unit;
Using a first roll mold having a plurality of optical elements and alignment mark molds, a plurality of optical elements and alignment marks are molded, molded or formed on one surface of the base film supplied from the base film supply unit. A first optical element forming unit for printing;
A mark detection unit for detecting an alignment mark formed on the base film in the first optical element formation unit;
A second optical element forming unit that is arranged downstream of the mark detection unit and that molds, molds, or prints a plurality of optical elements on the other surface of the base film using a second roll mold having a plurality of optical element molds. When,
An optical element sheet forming apparatus, comprising: a correction unit that corrects the rotation speed of the second roll mold or the conveyance speed of the optical element sheet based on a detection result of the mark detection unit.

5 . The first optical element forming section or the second optical element forming section supplies an ultraviolet ray curable resin to the first roll mold or the second roll mold, and the resin is cured with ultraviolet rays. 5. The optical element sheet forming apparatus as described in 4 above.

6 . 6. The optical element sheet forming apparatus according to 4 or 5 , wherein the correction unit performs speed correction for each mark detection.

7 . A conveying roller that contacts and conveys the optical element side formed in the first optical element forming portion or the second optical element forming portion, a grooved roller having a circumferential groove corresponding to the optical element forming portion, or 7. The optical element sheet forming apparatus according to any one of 4 to 6 , wherein the roller is a hollow roller having a hollow corresponding to the optical element forming portion.

  According to the present invention described above, when forming a plurality of optical elements by the optical element forming step on the surface of the base film and the subsequent optical element forming step on the back surface, the optical elements formed on the front surface and the back surface are displaced. It is possible to provide a method for continuously forming both sides of an optical element sheet and an optical element sheet forming apparatus capable of forming an optical element having no decentration between the front and back by reliably correcting the above.

The schematic diagram which shows the optical element sheet | seat formation apparatus of this invention. The schematic diagram which expand | deployed and showed the surface formation roll metal mold | die 3. FIG. The partial schematic diagram which shows the modification which makes the position of the optical element of a surface side and a back surface side correspond. The perspective view which shows the conveyance roller by the side of the optical element formation of this invention.

  Hereinafter, the present invention will be described with reference to the drawings. FIG. 1 is a schematic view showing an optical element sheet forming apparatus of the present invention.

  In FIG. 1, a base film F is wound around a base film supply roller 1 and is drawn out as shown by an arrow. The UV curable resin supply for supplying the UV curable resin between the base roller F and the transport roller pair 2, the surface forming roll mold 3, and the upstream side of the surface forming roll mold 3 in order. Unit 4, conveyance roller pair 5, conveyance roller pair 6, back surface forming roll die 7, ultraviolet curable resin supply unit 8 for supplying ultraviolet curable resin between the upstream side of back surface forming roll die 7 and base film F, A pair of conveying rollers 10 and a pair of conveying rollers 11 are arranged. Finally, the spacer sheet S supplied from the spacer sheet supply roller 12 is sandwiched between the molded optical element sheets and both are wound around the molded product roller 13.

  On the peripheral surfaces of the front surface forming roll die 3 and the back surface forming roll die 7, optical element molds to be formed are formed in a matrix shape, and heaters are provided in each of the molds, and UV curing is performed. It is comprised so that the temperature of resin may be managed uniformly.

  The ultraviolet curable resin supplied between the surface molding roll mold 3 and the base film F is irradiated with the ultraviolet irradiation lamps UV1 and UV2 from the side of the base film F to start curing. Further, the curing is completed by the ultraviolet irradiation lamps UV3 and UV4 arranged on the optical element forming side between the conveying roller pair 5 and the conveying roller pair 6.

  Similarly, the ultraviolet curable resin supplied between the back surface forming roll mold 7 and the base film F is irradiated with ultraviolet irradiation lamps UV5 and UV6 from the side of the optical element formed by the surface forming roll mold 3. Start curing. Next, the curing is completed by the ultraviolet irradiation lamps UV7 and UV8 arranged on the optical element forming side formed on the back side between the conveying roller pair 10 and the conveying roller pair 11.

  In the example of FIG. 1, as shown in an enlarged view, a convex lens La is formed on the front side and a concave lens Lb is formed on the back side.

  Thus, the optical elements formed on the front surface side and the back surface side must be formed so that their optical axes coincide. For this alignment, an alignment mark is formed at the side of the peripheral surface of the surface forming roll mold 3 simultaneously with the optical element formation.

  FIG. 2 is a schematic view showing the surface forming roll mold 3 in a developed state, and shows a part of the mold for forming optical elements arranged in a matrix form in the figure. A mold M for forming alignment marks is formed on one side of the surface forming roll mold 3. In the example shown in the figure, the mark forming mold M is arranged for every two rows of the mold for the optical element, but may be for every row or for every plurality of rows. Further, in order to see the detection reliability and the state of the base film in detail, there may be a plurality of detection marks M in place of one in the roll width direction.

  A mark detection unit 9 is provided downstream of the conveying roller pair 6 in FIG. 1 to detect an alignment mark formed on the base film F. The mark detection unit 9 includes a light source and a sensor. As described in the problem to be solved by the invention, since the positional deviation is in the micron order, the mark detection unit 9 also detects the mark with a resolution in the submicron order. Use what you can.

  In the embodiment of FIG. 1, the front surface forming roll mold 3 and the back surface forming roll mold 7 are configured to be driven by separate drive sources, and the back surface forming is performed based on the mark information detected by the mark detection unit 9. The rotational speed of the back surface forming roll mold 7 is controlled by controlling the drive source of the roll mold 7 so that the positions of the optical elements on the front surface side and the optical elements on the back surface side coincide. In addition, the conveyance speed of the base film F at this time is constant, and when the rotational speed of the back surface forming roll mold 7 is changed, the back surface forming roll mold 7 is slightly slipped with respect to the base film F and correct. It is adjusted to the optical element formation position. Since the slip amount at this time is very small, it does not hinder the optical element formation. Although a control means for performing this control is not shown, a known speed control configuration can be used.

  In order to match the position of the optical element on the front surface side and the optical element on the back surface side, in addition to controlling the rotational speed of the back surface forming roll mold 7 as described above, the conveyance speed on the downstream side of the base film F is set to It can also be changed. FIG. 3 is a partial schematic diagram showing this configuration.

  In FIG. 3, a position-fixed conveyance roller 21, a position-variable conveyance roller 22, and a position-fixed conveyance roller 23 are arranged between the mark detection unit 9 and the back surface forming roll mold 7, and the base film F Between these transport rollers.

  In the configuration of FIG. 3, control is performed so that the position of the transport roller 22 is moved based on information detected by the mark detection unit 9. A known configuration can be used as the configuration for holding and moving the conveyance roller 22 in a variable position. When the transport speed of the base film F on the upstream side of the transport roller 21 is V, when the transport roller 22 is moved in the positive or negative direction at the speed v, the transport speed of the base film F on the downstream side is V ± 2v. Thus, the position of the optical element to be formed on the back side is corrected.

  Thus, by correcting the rotational speed of the back surface forming roll mold 7 or the downstream transport speed of the base film F, the formation positions of the front surface side optical element and the back surface side optical element can be matched. Either mold rotation speed correction or base film conveyance speed correction may be used, or both may be used in combination.

  In the above embodiment, the mark is formed on the surface molding roll mold 3 and the speed of the back surface molding roll mold 7 or the conveyance speed of the downstream optical element sheet is corrected. Formed on both the mold 3 and the back surface forming roll mold 7, both marks are detected after the second optical element forming step, and the second optical is detected based on the detection result of the relative position on the base film. It is also possible to sequentially correct the rotational speed of the roll mold in the element forming step or the conveyance speed of the optical element sheet. In this case, the eccentricity cannot be corrected until the mark detection is completed, but the front and back eccentricity of the optical element can be corrected after the detection is completed.

  In the above description, the roll mold is precisely manufactured, and it is assumed that there is no shaft eccentricity or roll shape deviation, but it is difficult to completely eliminate these eccentricity and deviation, and the optical element to be formed The smaller the is, the greater these effects. Therefore, the shaft eccentricity and roll shape of the roll mold are measured in advance, the measured values are stored, and correction is performed using the stored eccentricity measured values and roll shape measured values when performing speed correction. You can do it. At this time, since rotational position information of the back surface forming roll mold 7 is required, the back surface forming roll mold 7 is marked and measured, or a rotary encoder is provided on the shaft to obtain rotational position information. Like that.

  In FIG. 1, the roller on the optical element forming side of the pair of transport rollers 5, 6, 10, and 11 is in contact with the formed optical element, and therefore, a rubber roller that does not damage the optical element can be used. For this, a roller that does not contact the optical element but contacts a portion between the optical elements is preferable. FIG. 4 shows such a roller. FIG. 4A shows a grooved roller having a structure in which a groove is formed in the circumferential direction and an optical element forming portion enters the groove. FIG. 4B shows an optical element. The hollow with a hollow in which the hollow corresponding to the formation part was formed in the matrix form in the surrounding surface is shown. In FIG. 1, a conveyance roller indicated by a double circle is a portion that employs the grooved roller or the recessed roller.

  A roller on the side opposite to the optical element forming side is not necessarily required. However, in order to prevent occurrence of slipping or the like, it is preferable to provide a transport roller on the opposite side and transport the paper as a pair of transport rollers.

  In the embodiments of the present invention described above, an ultraviolet curable resin is used as a material for forming the optical element. However, the ultraviolet curable resin is appropriately selected according to the performance of the optical element such as urethane acrylate, epoxy acrylate, or unsaturated acid polyester. it can. Further, instead of the ultraviolet curable resin, an energy ray curable resin such as visible light or an electron beam, or a thermosetting resin such as diethylene glycol diallyl carbonate or siloxanyl methacrylate may be used.

  As the ultraviolet irradiation lamp, a high pressure mercury lamp, a metal halide lamp, or the like can be used, and an LED type ultraviolet irradiation lamp developed in recent years can also be used.

  As described above, in the present invention, optical elements of various forms can be formed as optical elements in addition to lenses, and the forming method is “molding”, “molding”, and “printing”. Can do.

  The above-mentioned embodiment is “molding”, but in the case of “molding”, the resin is heated and softened, poured into a roll mold, and molded by heating and pressing. In the case of “printing”, the roll mold is an intaglio, and ink is put into the depressions of the mold and transferred to the base film by pressing. Of course, different methods can be used for the front side and the back side.

DESCRIPTION OF SYMBOLS 1 Base film supply roller 2, 5, 6, 10, 11 Conveyance roller pair 3 Surface forming roll metal mold 7 Back surface forming roll metal mold 4, 8 UV curable resin supply part 9 Mark detection part 12 Spacer sheet supply roller 13 Molded article roller F Base film S Spacer sheet M Mark forming mold UV1 to UV8 UV irradiation lamp 21, 23 Position-fixed transport roller 22 Position-variable transport roller

Claims (7)

A first optical element forming step of forming, molding or printing a plurality of optical elements and alignment marks on one side of the base film using a roll mold;
Continuously performing a second optical element forming step of forming, molding or printing a plurality of optical elements on the other side of the base film using a roll mold,
The alignment mark is detected between the first optical element formation step and the second optical element formation step, and the rotational speed of the roll mold in the second optical element formation step based on the detection result, or A method for continuously forming both sides of an optical element sheet, wherein the conveyance speed of the optical element sheet is sequentially corrected.   The first optical element forming step or the second optical element forming step is performed by supplying an ultraviolet curable resin to the roll mold and curing the resin with ultraviolet rays. The continuous double-sided formation method of the optical element sheet | seat.   The method for continuously forming both sides of an optical element sheet according to claim 1 or 2, wherein the speed correction in the second optical element forming step is performed every time the mark of the roll mold is detected. A base film supply unit;
Using a first roll mold having a plurality of optical elements and alignment mark molds, a plurality of optical elements and alignment marks are molded, molded or formed on one surface of the base film supplied from the base film supply unit. A first optical element forming unit for printing;
A mark detection unit for detecting an alignment mark formed on the base film in the first optical element formation unit;
A second optical element forming unit that is arranged downstream of the mark detection unit and that molds, molds, or prints a plurality of optical elements on the other surface of the base film using a second roll mold having a plurality of optical element molds. When,
An optical element sheet forming apparatus, comprising: a correction unit that corrects the rotation speed of the second roll mold or the conveyance speed of the optical element sheet based on a detection result of the mark detection unit. The first optical element forming section or the second optical element forming section supplies an ultraviolet ray curable resin to the first roll mold or the second roll mold, and the resin is cured with ultraviolet rays. The optical element sheet forming apparatus according to claim 4 , wherein Wherein the correction means is an optical element sheet forming apparatus according to claim 4 or 5, characterized in that the speed correction for each mark detection. A conveying roller that contacts and conveys the optical element side formed in the first optical element forming portion or the second optical element forming portion, a grooved roller having a circumferential groove corresponding to the optical element forming portion, or The optical element sheet forming apparatus according to any one of claims 4 to 6 , wherein the optical element sheet forming apparatus is a roller with a dent having a dent corresponding to the optical element forming portion.

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