JP4178856B2 - Method for manufacturing roll stamper for microlens array sheet - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a microlens array sheet and a manufacturing method thereof.
[0002]
[Prior art]
A so-called microlens array sheet in which substantially hemispherical unit lenses are two-dimensionally arranged has been proposed as a lens sheet used in a transmission screen or the like.
[0003]
Such a microlens array sheet is generally formed by a mold having an embossed reverse mold corresponding to its outer shape. Such a mold can be engraved on the surface of the mold member, or a photosensitive resin is applied to the surface of the mold member as a photoresist, and ultraviolet light is applied through the glass mask on which the embossed pattern is drawn. The film is manufactured by a so-called photo-etching method in which only a portion irradiated with light is cured by irradiating the film and a mold member is immersed in a developing solution to expose the cured portion to a required pattern.
[0004]
However, any of the above-described conventional mold manufacturing methods is for producing a mold member (flat stamper) for sheet-fed molding.
[0005]
JP-A-2001-30273 proposes a method for producing a roll mold for continuous molding. In this method, a unit lens is directly formed on a cylindrical surface serving as a roll stamper with a large area by laser light or the like.
For this reason, although there is an advantage that a roll stamper can be directly produced, it is necessary to form a uniform and high-accuracy pattern over a large area, resulting in a very high processing difficulty. In addition, it is difficult to produce a highly accurate and inexpensive lens sheet.
[0006]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION In view of the above points, an object of the present invention is to easily and inexpensively manufacture a roll lens stamper for forming a microlens array sheet, and to easily manufacture a high-precision, large-area microlens array sheet produced using the roll stamper. An object of the present invention is to provide a manufacturing method capable of performing
[0007]
[Means for Solving the Problems]
In the present invention, an uneven surface (normal or reverse) corresponding to an element pattern of a lens array in which substantially hemispherical unit lenses are two-dimensionally arranged at a pitch of 100 μm or less on a plane smaller than the area of the microlens array sheet to be manufactured. A relatively small sized flat original plate having
By rolling the first transfer roll cylinder while pressing the first transfer roll cylinder into the flat plate original plate, the reverse shape (reverse or normal) of the flat plate surface is circular. Producing a first transfer roll transferred and formed on the surface;
Preparing a second transfer roll cylinder having a larger area of the circumferential portion than the first transfer roll;
By rolling the first transfer roll and the second transfer roll cylinder while relatively pushing them together, an uneven surface (reverse or forward) formed on the circumferential surface of the first transfer roll. The process of transferring and forming the reverse shape (normal or reverse) on the circumferential surface of the second transfer roll cylinder is repeated at least once, so that the reverse shape (normal or reverse) of the uneven surface (reverse or normal) is the surface. A step of producing a master roll formed by attaching,
By finally preparing a third transfer roll cylinder to be a roll stamper and rolling the third transfer roll cylinder and the original roll while relatively pushing them together, the circumference of the original roll Forming a reverse shape (reverse) of the uneven surface (forward) formed on the surface on the circumferential surface of the third transfer roll cylinder;
A method of manufacturing a roll stamper is provided.
[0008]
In the above, “the area of the circumferential portion is large” means that the circumferential length of the circumference (that is, indicates that the diameter is large) / or the length in the direction perpendicular to the above (that is, the length of the cylinder is Satisfying at least one of the above).
[0009]
When the uneven surface formed on the flat plate precursor as the starting point is the reverse type of the uneven surface of the pattern of the microlens array to be finally manufactured, in the above step, the second transfer roll cylinder A master roll formed using the above becomes a roll stamper.
[0010]
In the present invention, since a flat original plate having an engraved surface corresponding to a high-precision microlens array having a relatively small area obtained by known photoetching or the like is used, the high-precision uneven shape of the original plate is changed to a roll stamper. By reflecting in the above, a lens sheet with high accuracy is formed even in a large area.
When applying a microlens array sheet to a transmissive screen, when producing a molding stamper of a size corresponding to a large size lens sheet of 30 inches square or more, a fine unit over a large size Forming a lens reverse mold with high accuracy is an operation that requires enormous time, labor, and cost.
[0011]
In the present invention, since the original size smaller than the lens sheet to be manufactured is used as a starting point, it is possible to reduce time, labor, and cost. However, a size of 6 inches square or less is suitable as a high-precision original. is there.
[0012]
Of the accuracy required for the original plate, the surface roughness is preferably about 2.5 μm. In the case of the original plate having a surface roughness of 2.5 μm or less and good smoothness, the smoothness should be accurately reflected in the lens sheet. it can.
[0013]
The original plate is prepared, and the flat plate original plate is pressed into a cylinder for an original plate roll to be engraved, whereby the flat plate original plate is multi-faceted and rolled to produce an original plate roll, and a roll stamper is prepared using the original plate roll. A highly accurate roll stamper can be easily manufactured by pushing and engraving into the cylinder for use. For this reason, a large-area microlens array sheet can be manufactured at low cost.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0015]
FIG. 1 is a diagram for explaining an embodiment of the present invention.
First, for example, a flat master 1 having an engraved surface corresponding to an element pattern of a lens array in which a substantially hemispherical unit lens having a lens diameter of 100 μm or less is two-dimensionally arranged on a plane having a size of 6 inches square or less is prepared. .
[0016]
As a method for producing the flat original plate 1, a mechanical cutting method using a cutting tool having an arbitrary curve shape, a photo etching method, or the like can be used.
The smaller the size of the flat original plate 1, the easier it is to form with high accuracy.
[0017]
When considering use as a transmissive screen, a fine pitch is desired also in a lens sheet constituting the screen in order to provide high-resolution video image quality. For this reason, it is preferable that the lens array pattern engraved on the flat original plate has a unit lens arrangement pitch of 100 μm or less.
The lens array pattern engraving surface is desired to have high surface accuracy, and the surface roughness is preferably 2.5 μm or less.
[0018]
The material of the flat plate precursor is not particularly limited as long as it has a hardness capable of being pressed and engraved into the cylinder for the master roll. A metal having a Shore hardness of 70 ° or more such as iron or nickel is preferably used.
[0019]
Next, as shown in FIG. 1A, the flat master 1 is pushed into the first transfer roll cylinder 2 for engraving. In order to manufacture the first transfer roll 3 by pressing the engraving shape of the flat master 1 into the first transfer roll cylinder 2, the first transfer roll cylinder 2 is rotated in contact with the flat master 1. However, it is sent while shifting by several pitches per rotation.
[0020]
Next, as shown in FIG. 1B, the first transfer roll 3 is pushed into another second transfer roll cylinder 4 so that the surface shape of the first transfer roll 3 is the second transfer roll use. After repeating the process of transfer forming (transfer engraving) on the cylinder 4 several times, the roll produced last becomes the master roll.
In general, the transfer process is repeated four or five times to remove unevenness.
In FIG. 1B, the first transfer roll 3 and the second transfer roll cylinder 4 are shown to have the same size, but the latter has a larger circumferential area than the former. It is essential.
[0021]
Moreover, it is possible to select whether the final engraving mold on the roll stamper is a normal mold or a reverse mold with respect to the lens mold of the original plate on the flat plate, depending on whether the number of repetitions of the transfer process is even or odd.
For this reason, as the flat plate-shaped original plate 1, an original plate having a reverse type (not the normal type) of the emboss necessary for the roll stamper can be used.
[0022]
In forming a highly accurate original plate pattern, a flat plate shape is more effective than a roll shape. However, in the present invention, a roll original plate may be used instead of the flat plate original plate 1.
Naturally, the smaller the number of repetitions of the transfer process, the less the deterioration of the accuracy of the flat plate precursor 1 is reflected on the roll stamper and the manufactured lens sheet.
[0023]
Further, as shown in FIG. 2, the master roll 5 is pushed into the embossing roll cylinder 6 for engraving. In order to produce a roll stamper by pressing the engraving shape of the original roll 5 into the roll stamper cylinder 6 and engraving the roll stamper, the roll stamper cylinder is rotated while being in contact with the original roll, and is sent while being shifted by several pitches per rotation.
The material of the roll stamper cylinder is not particularly limited, and those generally used as a roll stamper cylinder can be used without any problem.
[0024]
In general, the roll temperature at the time of molding greatly affects the moldability, so that a structure that can be set to an appropriate temperature is preferably used. A roll having an internal structure that can be easily adjusted in temperature by a heat medium such as water or oil is preferred.
[0025]
Hereinafter, a method for producing a microlens array sheet by a method using a radiation curable resin (2P method) using the roll stamper produced by the above-described method will be described.
[0026]
First, a translucent resin base film coated with a radiation curable resin by a coating apparatus is nipped with a nip roll with respect to a roll stamper. Then, with the surface of the translucent resin base film in contact with the roll stamper, the radiation curable resin is cured by irradiating radiation from the back side of the translucent resin base film, and the roll surface of the roll stamper A lens array corresponding to the pattern is formed.
Through the above steps, a microlens sheet having a lens array element pattern in which substantially hemispherical unit lenses are two-dimensionally arranged with a pitch of 100 μm or less is produced.
[0027]
In the above-described embodiment, the microlens array is formed by the method using the radiation curable resin using the roll stamper having the above-described configuration. However, the base film is continuously supplied to the surface of the roll stamper. Any existing method can be used as long as it can continuously transfer the engraving. For example, a desired microlens array sheet is produced by embossing a thermoplastic resin or the like using the roll stamper having the above configuration.
[0028]
【The invention's effect】
As described above, according to the present invention, this plane can be obtained by using a small-sized flat original plate (or a roll-shaped original plate) having a high-precision engraving surface produced by using a known photoetching method or the like. By engraving the sculpture shape of the plate-shaped original plate directly onto the roll stamper via the original plate roll, a roll stamper with a fine pitch between the lens portion and the lens portion and high surface accuracy can be easily and inexpensively manufactured. A large-area microlens array sheet can be easily manufactured.
[0029]
[Brief description of the drawings]
FIG. 1 is a schematic view showing an embodiment of the present invention, in which FIG. 1 (a) is a step of producing a first transfer roll using a flat plate precursor, and FIG. 1 (b) is an unevenness removing step and an original plate roll. Explanatory drawing which shows the process of producing.
FIG. 2 is an explanatory view showing a process for producing a roll stamper using an original roll.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Flat master 2 ... 1st transfer roll cylinder 3 ... 1st transfer roll 4 ... Transfer roll cylinder (original roll)
5 ... Original roll 6 ... Cylinder for roll stamper

Claims (3)

A flat original plate having an uneven surface (positive) corresponding to an element pattern of a lens array in which substantially hemispherical unit lenses are two-dimensionally arranged at a pitch of 100 μm or less on a plane smaller than the area of the microlens array sheet to be manufactured. Prepare
Preparing a first transfer roll cylinder having an area of the circumferential portion substantially equal to the uneven surface of the flat plate-shaped original plate;
By rolling the first transfer roll cylinder while being pressed into the flat plate original plate, a first transfer roll is produced in which the reverse shape (reverse) of the uneven surface of the flat plate original plate is transferred and formed on the circumferential surface. And a process of
Preparing a second transfer roll cylinder having a larger area of the circumferential portion than the first transfer roll;
The reverse shape of the uneven surface (reverse) formed on the circumferential surface of the first transfer roll by rolling the first transfer roll and the second transfer roll cylinder while relatively pushing them together. The master roll formed by imposing the reverse shape (forward) of the concavo-convex surface (reverse) by repeating the process of transferring (forward) on the circumferential surface of the cylinder for the second transfer roll at least once or more. And a process of
By finally preparing a third transfer roll cylinder to be a roll stamper and rolling the third transfer roll cylinder and the original roll while relatively pushing them together, the circumference of the original roll Forming a reverse shape (reverse) of the uneven surface (forward) formed on the surface on the circumferential surface of the third transfer roll cylinder;
A method for manufacturing a roll stamper. An uneven surface (reverse) corresponding to the reverse shape of the element pattern of the lens array in which substantially hemispherical unit lenses are two-dimensionally arranged at a pitch of 100 μm or less on a plane smaller than the area of the microlens array sheet to be manufactured. Prepare a plate-shaped master
Preparing a first transfer roll cylinder having an area of the circumferential portion substantially equal to the uneven surface of the flat plate-shaped original plate;
Rolling the first transfer roll cylinder while being pressed into the flat plate-shaped original plate, thereby producing a first transfer roll in which the reverse shape (positive) of the uneven surface is transferred and formed on the circumferential surface;
The area of the circumferential portion is larger than that of the first transfer roll, and a second transfer roll cylinder, which finally becomes a roll stamper, is prepared,
By rolling the transfer roll and the second transfer roll cylinder while relatively pushing them together, the reverse shape (reverse) of the uneven surface (forward) formed on the circumferential surface of the transfer roll is obtained. A step of producing a roll stamper formed by imposing a reverse shape (reverse) of the concavo-convex surface (forward) by repeating the step of transferring and forming at least once on the circumferential surface of the second transfer roll cylinder;
A method for manufacturing a roll stamper. Concave and convex surface corresponding to the shape (or reverse shape) of the element pattern of a lens array in which substantially hemispherical unit lenses are two-dimensionally arranged with a pitch of 100 μm or less on a plane smaller than the area of the microlens array sheet to be manufactured. As a flat original plate having
The method for producing a roll stamper according to claim 1 or 2, wherein a surface roughness of the irregular surface is 2.5 µm or less.

Images