JP2005001313A - Production method for optical element with projection for gap control - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a production method for an optical element in which a gap between the substrates can highly precisely be controlled. <P>SOLUTION: This optical element comprises the first and second substrates 2 and 8 and a resin retained between both substrates. The method for production thereof includes a process for forming, on the periphery of effective portion 1 of the first substrate 2, the projections 3 which abut on the outermost surface of the second substrate 8 to control the gap between the substrates, and a process for laminating both substrates 2 and 8. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing an optical element using a microlens array used in an LCD panel mounted on an optical apparatus such as a liquid crystal projector.
[0002]
[Prior art]
A microlens array is an assembly of two-dimensionally arrayed microscopic lenses having submicron order accuracy. By using a microlens, a liquid crystal projector is focused on a pixel aperture of a liquid crystal panel. It is an indispensable technology for optical devices in recent years, such as the improvement of the brightness of the laser beam and the ability to couple the light emitted from the semiconductor laser array to the fiber array with high accuracy.
[0003]
Here, the conventional method of forming a convex microlens is a convex lens shape in which a photosensitive monomer is polymerized by ultraviolet rays, and the exposed portion is swollen by the difference in osmotic pressure generated between the exposed portion and the non-exposed portion. And a method of obtaining a lens shape by surface tension after the photosensitive resin film is patterned in a circular shape and then heated and melted to a temperature higher than the melting point of the photosensitive resin.
The concave microlens is formed by a glass etching method or a base material in which a mask is formed on a glass substrate, and the glass substrate surface is etched using hydrofluoric acid or the like from the mask opening to form a hemispherical recess. There was a machining method for forming an uneven lens shape by machining.
Furthermore, there is a method of forming a microlens by forming a concave or convex original plate by the above-described method and then performing reverse transfer of the unevenness using this original plate.
[0004]
A substrate having a microlens obtained as described above and a counter substrate (a substrate having a microlens or a substrate having no microlens) are bonded together using a sealant, and two substrates are used for the purpose of adjusting the focal length, etc. An optical element can be obtained by injecting a resin into the gap of the resin and curing it. However, if there are bubbles in the injected resin, the refractive index of air and the refractive index of the resin are different. It becomes a fatal problem.
[0005]
Here, as an adhesion method for eliminating bubbles in the resin, both the flat plate in which the resin hangs down from a part of the lower surface and another flat plate in which the resin is applied to a part of or the entire upper surface are overlapped. A method of bonding flat plates to each other has been proposed (see, for example, Patent Document 1).
In this method, the resin adhering to the lower surface of the upper flat plate to be bonded hangs down to one, the lower end surface becomes a smooth curved surface due to surface tension, and contacts the resin adhering to the upper surface of the lower flat plate at one point, Resins in contact with each other will gradually spread from the point-like contact state to the surroundings due to the surface tension. In this way, the contact surfaces of the resins are bonded together and spread over the entire surface, and the two flat plates are joined by the resin. In this way, since the resin gradually spreads between the two flat plates from a dotted shape to a planar shape, there is no space between the resin and the flat plate to be bonded as in the conventional case, and bubbles are formed in the resin. This is an adhesion method that does not occur.
[0006]
As another bonding method, a spin coater in which a substrate fixed by a spin coater is spun at a constant speed, a resin is dropped from directly above the center position, the resin is uniformly applied by centrifugal force, and then the substrates are overlapped. And a DVD (Digital Versatile Disc) manufacturing method in which a resin is applied to the center of two disc substrates, spun while pressing from above and below, the resin is uniformly applied, and then the resin is cured and bonded to the substrate. There are laws.
[0007]
[Patent Document 1]
JP-A-8-209076 (page 2-6, FIG. 1)
[0008]
[Problems to be solved by the invention]
However, any of the above bonding methods has a problem that it is difficult to control the gap between the substrates.
[0009]
The present invention has been made in view of the above points, and an object of the present invention is to provide a method for manufacturing an optical element capable of controlling a gap between substrates with high accuracy.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, according to the method of manufacturing an optical element having a protrusion for gap control according to the present invention, a first substrate having a plurality of effective portions on which microlens arrays are formed, Manufacturing of optical element having protrusion for controlling gap holding resin in gap between first substrate and second substrate, and second substrate arranged facing one substrate with predetermined gap A method for providing a predetermined gap between the first substrate and the second substrate in contact with the outermost surface of the second substrate at the periphery of the effective portion of the first substrate. A seal pattern on the periphery of the first substrate or the second substrate so that at least one opening is formed when the first substrate and the second substrate are bonded together. And bonding the first substrate and the second substrate together Comprises that the step, and curing the seal pattern, a step of filling the resin from the opening, and curing the resin.
[0011]
Here, by forming a protrusion that is in contact with the outermost surface of the second substrate and provides a predetermined gap between the first substrate and the second substrate at the periphery of the effective portion of the first substrate. The gap between the first substrate and the second substrate can be controlled with high accuracy.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings to provide an understanding of the present invention. FIG. 6 is a process flow for explaining an example of an optical element manufacturing method to which the present invention is applied.
[0013]
FIG. 1 is a schematic diagram for explaining an example of a manufacturing method of an optical element to which the present invention is applied. First, an example of a manufacturing method of an optical element to which the present invention is applied is shown in FIG. Similarly, general-purpose photolithography technology and etching technology are used for the base glass 2 having a plurality of effective portions 1 patterned in the shape of the microlens array and capable of transmitting light having a wavelength of 400 nm to 700 nm for 60% or more. Then, as shown in FIG. 1B, a protrusion 3 made of resin whose height is finally equal to the substrate gap is formed in the peripheral area of the effective portion, that is, the area where the microlens array shape is not patterned. To do.
[0014]
Here, it is sufficient that the effective portion can function as a microlens by laminating a cover glass and injecting resin in a process described later, and the shape of the microlens array is a base glass as shown in FIG. Spherical or aspherical concave shape, spherical or aspherical convex shape protruding from the surface of the base glass as shown in FIG. 2 (b) and no projection from the surface of the base glass as shown in FIG. 2 (c) A spherical or aspherical convex shape of the state can be considered. Further, it is not always necessary to form the microlens array shape by patterning the base glass. As shown in FIG. 2D, the organic body (1) 4 formed on the upper layer of the base glass has a spherical or aspherical surface. As shown in FIG. 2E, the organic body (2) 5 formed on the upper layer of the base glass may be subjected to spherical or aspherical concave patterning as shown in FIG.
[0015]
The use of a base glass capable of transmitting light having a wavelength of 400 nm to 700 nm for 60% or more requires that light having a wavelength of 400 nm to 700 nm be transmitted for 60% or more in order to be an optical element. Because it is done.
[0016]
The protrusion is formed so that its height is finally equal to the gap between the substrates, and it is sufficient if the gap between the substrates can be adjusted. Although it may be formed, some gap correction is possible at the time of bonding, and in order to reduce damage to the cover glass due to the protruding portion at the time of bonding, it is better to form the protruding portion with an organic substance. preferable.
[0017]
Next, as shown in FIG.1 (c), the seal pattern which has the opening part 6 is made into the filler which consists of a 0.5-20 mass% gap control material (not shown) and the inorganic material for moisture permeability control. (Not shown) epoxy-based, acrylic-based, or mixed epoxy-acrylic-based seal resin 7 cured by light mixed with light, heat, or both. It is applied around the base glass by a dispensing method in which a pattern is drawn while being extruded by nitrogen or by screen printing.
[0018]
Here, when the gap between the base glass and the cover glass can be sufficiently adjusted by the protrusion formed in the peripheral region of the effective portion, it is not always necessary to mix the gap control material with the sealing resin, It is preferable that a gap control material is mixed with the sealing resin so that the gap between the base glass and the cover glass can be adjusted with higher accuracy.
[0019]
Subsequently, as shown in FIG. 1 (d), alignment is performed with the alignment mark 9 and the external shape provided on the base glass and the cover glass 8, so that the protrusions formed on the base glass come into contact with the cover glass. A base glass and a cover glass are bonded together. As described above, in order to be an optical element, it is necessary to transmit light having a wavelength of 400 nm to 700 nm by 60% or more, and therefore, a cover glass that satisfies this condition is used.
[0020]
Here, it is sufficient for the cover glass to be bonded to the base glass to function as a microlens by injecting a resin into the gap between the base glass and the cover glass in a process described later, and the shape of the cover glass is a flat plate. Alternatively, the microlens array shape may be patterned similarly to the base glass. As shown in FIG. 2, the shape of the micro lens array of the cover glass is similar to the above-described base glass. The cover glass has a spherical or aspherical concave shape, and the spherical or aspherical surface protrudes from the surface of the cover glass. Convex shapes and spherical or aspherical convex shapes that do not protrude from the surface of the cover glass are conceivable, and the organic substance (1) formed in the upper layer of the cover glass may be subjected to convex patterning. A concave shape may be applied to the organic body (2) formed in the upper layer of the cover glass.
[0021]
Further, when the microlens array shape is patterned on the cover glass as in the case of the base glass, the size and number of pixels in the optical effective area are the same, and the overlay accuracy is preferably within ± 1 μm. .
[0022]
Next, after the sealing resin is cured by light or heat, or both, a resin that has been subjected to defoaming treatment by leaving it in a reduced-pressure atmosphere or the like is placed in the gap between the base glass and the cover glass. Use and fill using the pressure difference.
[0023]
Here, as shown in FIG. 3A, the vacuum chamber 11 forming the vacuum injecting apparatus is depressurized by a vacuum pump 12, and a base glass and a cover are placed inside the vacuum chamber so that the opening portion faces downward. A table for setting a required number of cells 13 bonded with glass is provided. In this table, as shown in FIG. 3B, a resin port 14 in which molten resin 10 is stored in a heaped state is installed so that it can be moved up and down by an elevator 15. Note that a valve (not shown) is provided in the vacuum chamber, and nitrogen gas similar to an inert gas enters and exits to prevent oxidation of the resin and the cell.
[0024]
When injecting the resin using the vacuum chamber as described above, the resin port is raised by an elevator in an environment where the pressure is reduced to 100 Pa or less so that the molten resin is in contact with the opening of the cell, Thereafter, the vacuum pump is operated to increase the pressure inside the vacuum chamber, and the resin enters from the opening of the cell due to the pressure difference, and fills the gap between the base glass and the cover glass.
[0025]
In addition, the resin is injected from a reduced pressure state of 100 Pa or less, which is sufficient to fill the gap with the resin, at least once and maintained at an arbitrary pressure for an arbitrary time (for example, 1 minute or more), and thereafter By adopting a multi-stage boosting method in which the pressure is increased to the pressure, the resin can be gradually and reliably filled.
[0026]
Here, as long as the resin can be filled in the gap portion between the base glass and the cover glass, the method may be any method such as a dispense method, and the filling method using the above-described vacuum chamber and utilizing the atmospheric pressure difference. Of course, it is not limited to.
[0027]
The resin filled in the gap between the base glass and the cover glass has a higher refractive index than the refractive index of the organic substance (1) or the organic substance (2) formed in the upper layer of the base glass or the cover glass. It has a low refractive index, and the difference in refractive index between the two with a pattern portion formed in the base glass, cover glass, organic substance (1) or organic substance (2) as a boundary is 0.05 or more. The resin is selectively filled and the focal length is adjusted. This resin is cured by light, heat, or both.
[0028]
That is, when a flat cover glass is bonded to a base glass patterned with a spherical or aspherical concave shape as shown in FIG. 4 (a), or a spherical or aspherical concave shape as shown in FIG. 5 (a). The refractive index of the resin (c) 16 filled in the gap between the base glass and the cover glass when the cover glass patterned with a spherical or aspherical concave shape is bonded to the base glass patterned with nc is _denoted by nc. When a flat cover glass is bonded to a base glass patterned with a spherical or aspherical convex shape protruding from the surface of the base glass as shown in FIG. 4B, the base glass as shown in FIG. FIG. 5B shows a case where a flat cover glass is bonded to a base glass patterned with a spherical or aspherical convex shape that does not protrude from the surface of the substrate. When a cover glass with a spherical or aspherical convex part protruding from the surface of the cover glass is pasted on a base glass patterned with a spherical or aspherical convex part protruding from the surface of such a base glass Alternatively, as shown in FIG. 5C, a cover glass in which a spherical or aspherical convex portion that does not protrude from the surface of the cover glass is patterned on a base glass patterned with a spherical or aspherical convex portion that does not protrude from the surface of the base glass. filled into a lamination gap of the base glass and the cover glass in the case and the refractive index of the resin (d) 17 and n _d, patterned into a spherical or aspherical convex shape as shown in FIG. 4 (d) is facilities In the case where a flat cover glass is bonded to the base glass formed in the upper layer of the organic body (1), or in FIG. A base glass having a spherical or aspherical convex shape patterned as shown in the figure, and an inorganic body 18 having a spherical or aspherical convex shape patterned thereon is formed on the upper layer. filling the gap in the base glass and the cover glass in the case of bonding a cover glass formed on the refractive index of the resin (e) 19 and n _e, FIG. 4 (e), such a spherical or aspherical as shown in When a flat cover glass is pasted on the base glass formed on the upper layer of the organic material (2) patterned in the concave shape, or in a spherical or aspherical concave shape as shown in FIG. The organic glass (2) subjected to the patterning is bonded to the base glass formed on the upper layer thereof and the cover glass formed on the upper layer of the inorganic substance patterned on the spherical or aspherical concave shape. The refractive index of the resin (f) 20 to fill in the gap of the base glass and the cover glass when an n _f, based glass and the refractive index of the cover glass and n _0, the refractive index of the organism (1) n _a and the refractive index of the organism (2) and _{n b,
n b, n e, n d} <n 0 <n a, n f, n c
The resin is selectively filled so that the above relationship is established.
[0029]
In an example of a method for manufacturing an optical element to which the present invention is applied, the protrusion formed on the base glass contacts the cover glass to form a predetermined gap between the base glass and the cover glass. Since the uniformity of the gap with the glass can be maintained, the yield and quality can be improved.
[0030]
That is, if the gap material is only mixed in the sealing resin, the position for controlling the gap of the substrate is separated from the effective portion, so that it is difficult to control the gap of the substrate at a position away from the seal pattern. On the other hand, in the method of manufacturing an optical element to which the present invention is applied, high-precision uniformity can be ensured because the gap of the substrate is controlled in the vicinity of the effective portion.
[0031]
The gap control material is mixed not only in the seal resin but also in the resin that fills the gap between the base glass and the cover glass. It is considered that the gap of the substrate can be controlled in the inner region of the substrate, but if the resin mixed with the gap control material is filled in the gap between the base glass and the cover glass, the gap control material may enter the effective portion. On the other hand, in the example of the manufacturing method of the optical element to which the present invention is applied, since the convex portion is formed in the peripheral portion of the effective portion, the gap between the substrates is controlled without causing the above-described problems. can do.
[0032]
Further, by filling a resin subjected to defoaming treatment in advance by adopting a multi-stage pressurization method, it is possible to obtain a high quality and uniform optical element with less bubbles.
[0033]
【The invention's effect】
As described above, according to the method for manufacturing an optical element of the present invention, the gap between the substrates can be controlled with high accuracy, and the yield and quality can be improved.
[Brief description of the drawings]
FIG. 1 is a schematic diagram for explaining an example of a process of an optical element manufacturing method to which the present invention is applied.
FIG. 2 is a schematic cross-sectional view for explaining the shape of a microlens array.
FIG. 3 is a schematic diagram for explaining a vacuum chamber.
FIG. 4 is a schematic cross-sectional view (1) of an optical element.
FIG. 5 is a schematic cross-sectional view (2) of the optical element.
FIG. 6 is a process flow schematic diagram.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Effective part 2 Base glass 3 Protrusion part 4 Organism (1)
5 Organism (2)
6 Opening 7 Seal resin 8 Cover glass 9 Alignment mark 10 Resin 11 Vacuum chamber 12 Vacuum pump 13 Cell 14 Resin port 15 Elevator 16 Resin (c)
17 Resin (d)
18 Inorganic 19 Resin (e)
20 Resin (f)

Claims (6)

A first substrate having a plurality of effective portions on which a microlens array is formed; a second substrate disposed opposite to the first substrate with a predetermined gap; and the first substrate and the second substrate. A method of manufacturing an optical element having a protrusion for controlling a gap while holding a resin in the gap,
Forming a protrusion that is in contact with the outermost surface of the second substrate at the periphery of the effective portion of the first substrate to provide a predetermined gap between the first substrate and the second substrate; ,
Forming a seal pattern on the periphery of the first substrate or the second substrate so that at least one opening is formed when the first substrate and the second substrate are bonded together;
Bonding the first substrate and the second substrate;
Curing the seal pattern;
Filling the resin from the opening;
A method of manufacturing an optical element having a protrusion for controlling a gap, comprising a step of curing the resin. The method of manufacturing an optical element having a protrusion for gap control according to claim 1, further comprising a step of cutting the first substrate, the second substrate, and the resin. The second substrate has a plurality of effective portions on which a microlens array is formed,
The method of manufacturing an optical element having a protrusion for gap control according to claim 1, wherein the protrusion is in contact with a peripheral portion of an effective portion of the second substrate. 4. The method of manufacturing an optical element having a protrusion for gap control according to claim 1, wherein the protrusion is made of an organic material. 5. The gap control according to claim 1, claim 2, claim 3, or claim 4, wherein the first substrate is made of an inorganic material or an organic material that transmits at least 60% of light having a wavelength of 400 nm to 700 nm. Of manufacturing an optical element having a protrusion. The said 2nd board | substrate consists of an inorganic body or an organic body which permeate | transmits 60% or more of the light which has a wavelength of 400 nm-700 nm, The claim 1, Claim 3, Claim 4 or Claim 5 A method for manufacturing an optical element having protrusions for controlling a gap.

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