KR100461558B1 - Process and device for manufacturing networks of microlenses - Google Patents

Abstract

The device of the invention comprises at least one group 9 _i composed of a housing 1 and a plate 24 _i made of a malleable material under pressure at the temperature set in the housing heating means 2 and the housing 1. Means for supporting the inside of the housing. In addition, the group 9 _i comprises molds 25 _i , 25 ₁ ′, 25 ₂ ′ which are substantially planar, each mold comprising at least one non-conductive pit face under pressure at this temperature. The molds 25 _i , 25 ₁ ′, 25 ₂ ′ are inserted between the plates 24 _i . Means 13, 15, 19, 20, 21 are provided for providing an almost uniform pressure to the entire group 9 _{i in} a direction perpendicular to the surface of the plate 24 _i . The pressure is suitable for causing the microlens convex surface to appear on the surface of the plate 24 _i opposite the pit surface of the molds 25 _i , 25 ₁ ′, 25 ₂ ′.

Description

Microlens network manufacturing method and apparatus {PROCESS AND DEVICE FOR MANUFACTURING NETWORKS OF MICROLENSES}

Referring to French Patent No. 9,408,420, filed July 7, 1994, the applicant can see that this network can be created by the method of the type mentioned in the preamble of the present specification. According to the method, the plate made of the malleable material is pressed against the non-conductive pit surface, with both sides of the plate subjected to different pressures. The pressure on the surface facing the pit surface is less than the pressure applied to the other surface of the plate. The depth of the pit is greater than the thickness of the convex portion of the microlens formed by permanently bending the plate with respect to the pit surface. Contactless between the bottom of the pit and the convex portion of the microlens preserves the "optical" processing for these parts.

In order to carry out the method, the aforementioned French patent application has proposed a device comprising a waterproof sheet for a fluid, a rigid support having a plate support means and an pit face made of optical material. They are parallel to and close to each other. Thus, the plate constitutes part of the housing wall. In addition, the patent application proposes a means for setting the hydraulic pressure at a different level than the surface hydraulic pressure of the plate opposite the plate defining the housing, so that the plate fits at the moment when the means used for pressure setting is actuated. Squeezed against the face. In order to improve the productivity of the device, the device may comprise a plurality of overlapping housings. Each housing is defined by two optical plates lying on opposing faces, each of which lies next to the corresponding pit face. The means for setting hydraulic pressure in these housings are operated simultaneously.

By producing multiple microlens networks at the same time, the desired productivity gains are achieved. Nevertheless, the device must include a plurality of overlapping housings with complex laminate appearance of optics, seats with pit faces, supports, crossbars and sealing gaskets. Assembly and disassembly of such complex devices limits the productivity of the device.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for fabricating a network of microlenses, and more particularly to a grooved nonmalleable surface of a constant pits network whose openings correspond to the convex contours of the microlenses. A method of compressing a plate made of a malleable material, the opening being formed by permanently pressing the plate against a pitted surface. The invention also relates to an apparatus for carrying out the method.

Recently, optical microlens networks have been used in various ways, in particular, for image acquisition and reproduction. In this art, video image projectors are known that operate by projecting light across a two dimensional matrix of liquid crystal cells representing a projected image. Such an image projector has a low luminous rate due to various levels of light absorption by polarizers (polarization filters) placed on both sides of the matrix, opaque edges of the matrix cells, projection screens, and the like. For this reason, it is possible to improve the current emission rate (about 1%) by two or three times by concentrating the light source in the effective area of the liquid crystal cell in which the state is selectively changed to opaque and transparent. Thus, absorption by the opaque edge of the cell is avoided. This absorption problem is also found in other devices such as backlight liquid crystal screens used for data processing for information display.

Considering the matrix size of the liquid crystal cell currently in use and the high resolution of the popular video image, the two-dimensional network of the microlenses should be arranged to be distributed about 100 μm. One example would be between hundreds of thousands and millions of lens networks.

1 is a schematic vertical cross-sectional view of a device according to the invention,

2 to 4 are views showing various structures of a plate and a mold group pressed in the apparatus of FIG.

FIG. 5 shows a method for marking two molds in the same plate and mold group as in FIG. 4, FIG.

6 is a vertical sectional view of the pressure providing means which is part of the device of FIG.

7 is a schematic illustration of a transmission means suitable for ensuring automatic and continuous power supply to the device of FIG.

It is an object of the present invention to provide a microlens network manufacturing apparatus and method which is suitable for low manufacturing cost and mass industrial production and designed to ensure high productivity.

The object of the present invention is achieved by a method of manufacturing a microlens network of the type described in the preamble of the present specification, along with other features which will be appreciated while reading the following description. It is characterized in that it forms a group consisting of a plurality of molds comprising at least one non-conductive pit face. The mold is inserted between the plates such that at least one surface in each plate is disposed opposite the pit surface of the mold. When the group is created, a very uniform pressure is applied to the whole group, which is directed perpendicular to the surface of the plate.

Plate and mold groups are quickly assembled and disassembled. This can be done automatically. Continuous pressure setting for the plate group can also be automated, which allows to achieve high productivity.

The following other features of the method according to the invention ensure the isostatic pressing of the plate and mold groups in order to produce a microlens network with uniform optical properties on the entire surface of the network.

Other features and advantages of the method and apparatus according to the invention will be appreciated from the following description and the accompanying drawings.

Referring to the accompanying FIG. 1, the drawing shows, for example, a heat-insulating housing 1 made of a refractory alloy such as Nilimpi® (trademark) of Imp. Limited, and an inner space part 3 of the housing 1. An apparatus comprising a means 2 for doing this is shown. The housing 1 may be insulated with a blanket 4 made of an insulating fibrous material. The space 3 is sealed by a sliding door 6 and an insulating shield 5 mounted on the groove 7.

A horizontal rail 8 is mounted to the space 3 to accommodate a plate made of a malleable material and a group of flat molds 9 ₁ , 9 ₂ ,... Inserted between the plates. As described below, this allows the group to be sent to the crimp post 10 and allows for the extraction of the post. The rail is firmly coupled with the blanket 4 of the support frame 11 for the device.

The door 6 intersects an adjusting rod 12 which can slide horizontally into the door. The rod makes it possible to continuously move and mark different groups 9 ₁ to 9 ₃ in the heating, pressing and cooling positions.

As is well known in an oven for heat treatment, means (not shown) are provided for maintaining an inert nitrogen environment in the space of the input post 10.

The crimp post 10 includes a bottom plate 13 and a mold 14, which is shown in more detail in FIG. 6. The mold 14 is mounted on the vertical axis of the support 15 by the joint 16, and the axis of the joint is perpendicular to the vertical axis of the support 15 for the reasons described below. The mold 14 is brought into contact with the corresponding support region 17 ₁ (17 ₂ ) of the group 9 _i ( _i in the embodiment shown in FIG. 1) 1 to 3 arranged in the crimp post 10. It has two protrusions 14 ₁ and 14 ₂ arranged.

The bottom plate 13 is mounted on the shaft 18 so as to move vertically to form a joint with the tip of the lever 19 (see FIG. 1), the lever being provided by a jack (actuator) 20. It is operated to rotate about the shaft 21 to bring the bottom plate 13 close to the mold 14 and then to continuously move the mold while the group 9 _i is pressed in the post 10.

Referring to FIG. 2 to explain the configuration of such a group, the group defines a grooved surface formed of a regular pit network between two thick metallic blocks 22 and 23 constituting a corresponding bottom plate and a corresponding mold. And a layer of glass plate or sheet 24 _i interposed between the excitation metallic sheet 25 _i . Each sheet 25 _i constitutes a substantially planar mold, which becomes a non-conductive pit face.

The plate group is finished with a sheet 26 made of a compressible material which is a good thermal conductor, such as graphite, placed in one of the blocks 22, 23 (here block 22) for the purpose described below. The sheet 26 is separated from the neighboring glass plates of the group by the insertion sheet 27 whose function is described below.

The construction and manufacture of the glass plate 24 _i and the mold 25 _i (referred to above as sheets) are described in the aforementioned French patent application and in French Patent Application No. 9,502,983 filed March 15, 1995 by the present applicant. Exactly the same as the description. More details on this can be found in the above application. This shows how a glass of Corning Incorporated's catalog reference number 7059 can be used to produce a plate 24 _i , for example 9 × 12 cm, the thickness being selected from a large range from 0.2 mm to 5 mm. Can be. In the present invention, it is generally preferred to use glass at low hammering and high softening temperatures (eg 630 ° C. or higher) by compression in the thermal cycle between liquid crystal display production processes. 25 _i ) can be made, for example, of the NiCrimpy 600 metal alloy sheet described above, the thickness being for example from 0.2 mm to 0.3 mm. It is not malleable under the temperature (up to 750 ° C.) and pressure conditions of the process according to the invention. Nevertheless, the thin thickness of the mold contributes to the transfer of pressure without disturbing the pressure field as described below.

Pieces of the pits are performed by photolithography as described in the aforementioned patent application. As described in detail in the foregoing patent application, the printing depth is naturally larger than the thickness of the convex portion of the lens formed by pressing the glass plate to provide an optical finish on the convex surface of the lens.

Preferably, the mold 25 _i is covered with an adhesive such as boron nitride or soot in order to avoid physicochemical interaction between the plate and the mold such as adhesion during the pressing operation of the plate group 9 _i .

The pressing gear, the bottom plate 13, the mold 14, the corresponding bottom plate 22, and the corresponding mold 23 have a high temperature (set in the space portion 3) to change the glass plate into a plastic state suitable for the passage of the plate. Sufficient mechanical properties at approximately 750 ° C.). NS 30 (AFNORZ12CN25-20) is suitable for manufacturing crimped gears under these conditions.

The following describes the useful features of the present invention. The sheet 26 is used to eliminate the surface non-uniformity of the corresponding bottom plate 22 due to its compressibility, and to suppress the concentrating concentration region during the pressing process so as to achieve an advantageous excellent pressing uniformity of the glass plate group 9 _i . The uniformity along with the glass temperature depends on the constant of the optical properties of the microlenses formed on the entire surface of each plate. For this purpose, the sheet 26 may be made of a graphite sheet having a thickness of 0.8 mm. It is sold by SL Carbon Carbon GmbH, under the name Siggraphplex V 10010C4. Its excellent thermal conductivity allows the metallic mass constituent counterplate 22 to play an important role in standardizing glass temperatures across the entire group thickness.

The insert sheet 27 may be made of an unprinted nicklepi 600 sheet and may be covered with an adhesive as described above. This prevents the graphite sheet from touching the adjacent glass plate 24 _i .

The method of manufacturing a microlens network according to the present invention, which is carried out with the aid of the apparatus shown in FIG. 1 and the group as shown in FIG. 2, is made in the following manner.

After inducing one or several groups 9 _i to the space 3, the first group () between the mold 14 of the crimp post 10 and the bottom plate 13 using the adjusting rod 12 is used. 9 ₁ ) Push in. In order for the ambient temperature of the glass plate to reach approximately 750 ° C. at an intermediate level of 450 ° C., the electrical heating means is operated to regulate the thermal cycle behavior in the onve. When the glass is stabilized at 750 ° C., the jack 20 is activated for approximately tens of seconds to apply several tons of pressure to the group. The jack is then released to allow the group 9 ₁ to leave the crimp post 10 and to push the group 9 ₂ out by the rod 12. The above described pressing operation is repeated in this group and the next group 9 ₃ . The group treated in this way is transferred back to the oven's ambient temperature and disassembled in order to remove the glass plate 24 ₁ , which is subjected to "no contact" during the crimping operation as described in French Patent Application No. 9,408,420. "Support the formed microlens network.

Since the properties of the device according to the invention ensure isostatic pressing of the glass plates, the optical properties and structure of the microlenses formed in this way are perfectly uniform over the entire surface of the network. The isostatic pressing may, on the one hand, be carried out due to the presence of the graphite sheet 13 for the reasons mentioned above, on the other hand, by the mold being jointed to the support 15. These two devices allow the pressure generated by the jack 20 to be evenly distributed over the entire volume of the group being compressed. In addition, the thin thickness of the molding sheet provides the sheet with weak inertia that does not disturb the transfer of pressure given to the sheet. However, the high mechanical properties of the nickel crimp at high temperatures ensure local pits and relative positions of the pits.

Of course, the joint of the mold to the support 15 may be replaced by a joint of the bottom plate 13 on the shaft 18.

By the way, it has been found that the rails are isolated from the conditions set by the jacks 20 by raising the group 9 _i over the support rails 8 in the pressing process.

Glass sheets and mold groups arranged differently than those shown in FIG. 2 can be pressed in the apparatus according to the invention. Another possible stack is shown in FIGS. 3 and 4. In FIG. 3, the stack includes four plates 24 _i and two molding sheets 25 ₁ ′ 25 ₂ ′. Each of these sheets is printed on both sides with a pit network. Molds 25 ₁ ′ and 25 ₂ ′ are respectively located between the plates 24 ₁ and 24 ₂ and the plates 24 ₃ and 24 ₄ . The insert sheet 27 separates the plates 24 ₂ and 24 ₃ , and the other insert sheet has two tip faces of the enclosed group as shown in FIG. 2 between the corresponding bottom plate and the corresponding mold (not shown). Are connected to each. It is clear that this arrangement allows the production of many microlens networks as in FIG. 2 with two molding sheets instead of four.

In FIG. 4, the group comprises four glass plates 24 _i and five molds 25 ₁ to 25 ₅ ; Each of these is printed on only one side. The plate 24 ₁ is enclosed between two molds 25 ₁ and 25 ₂ which form a convex lens network on each of both sides of the plate 24 ₁ after pressing. Other plates (24 ₂ to 24 ₄₎ is a plate, such as 2 and of the groups shown in Figure 3, has only one microlens network.

It can be seen that the configuration of FIG. 4 allows each network to form a biconvex microlens network with stronger concentration than planar convex lenses, which is interesting in certain applications. In addition, the microlens of one of the networks supported by the plate 24 ₁ need to be perfectly centered on one of the lenses of the other network. For this purpose, the two molds must be arranged with respect to one another, for example along the markings schematically represented in FIG. 5. The positions of the circular hole 28 and the long hole 29 are simultaneously printed on each mold. Perforation of the holes is often made of self-centered micromilling. In the process of squeezing the network to the plate, very precise (± 5 μm) pins 30 and 31 maintain the two pit networks at the marking locations on both sides of the plate.

As a variant, the marking can be formed in the micromilling process by means of small spheres (not shown) placed between two pit networks. Centering is accomplished by placing each ball on two feet opposite each other, so that the feet are perfectly centered with respect to each other.

It can be seen that the present invention ensures microlens network mass production by compressing several networks simultaneously. Since the molds used can be produced by photolithography, which is now a fully mastered mass production method, manufacturing costs are kept low. For example, if excellent resistance to the oxidation of materials used in mold production, such as Ni cream p 600, it can be crimped in a free environment up to 850 ℃. Nevertheless, the life of the mold is increased by setting an inert nitrogen environment in the space 3 by conventional means (not shown).

Isocompression molding according to the invention ensures the production of microlens networks with uniform optical properties over the entire surface. Preferably such compaction occurs at a strong glass viscosity, ie, at a viscosity of approximately 10 ¹⁰ poise for 1 to 2 minutes at a pressure of 20 to 50 bar depending on the desired type of microlens to ensure the relationship of the dimensional error. The heat cycle of the glass rough in the space 3 ensures tempering of the glass, which ensures hammering by homogeneous consolidation during the cooling of the glass. The cooling ramp may preferably be low speed and adjusted to ensure microlens size reproducibility of greater than ± 5 μm per 100 mm. Controlled modifications to the cooling lamp allow for fine size adjustment without degrading either the surface condition of the network or the optical properties of the lens.

The method according to the invention is suitable for automation in network fabrication which further increases the productivity of the device according to the invention. For this reason, in FIG. 7 schematically showing an embodiment of the device according to the invention, a delivery means is provided which ensures an automatic continuous passage of the group 9 _i to the device. The apparatus comprises, for example, a tunnel 32 in which a conveyor of group 9 _i is disposed with a gas cushion. The conveyor receives a preformed group 9 _i from a charging terminal 34. The group is moved on the conveyor to the crimp post 10 and removed with a draining terminal 35. The heating means 2 _j distributed along the length of the tunnel establish the above-described heat cycle. Various forms of planar product (not shown) processing means well known in the art can ensure the automatic production of groups and the automatic extraction of microlens networks excluding groups from the device according to the invention.

Of course, the present invention is not limited to the embodiments and detailed description shown by way of example only for explanation. In particular, like ultrasonic waves, the present invention can be applied to fabricate microlens networks by concentrating sound waves rather than light waves. The invention also extends to the compression of the microlens network in contact between the plate made of the malleable material and the pit bottom of the mold. Thus, the material fills the pit, which is not the case when there are processes described in more detail in the two French patent applications Nos. 9,408,420 and 9,502,983 described above and mentioned in the preamble of the present description. At this time, the device according to the invention must be provided with means for vacuum forming in the space 3 in order to prevent the gas bubbles from being suppressed so that the malleable material does not completely fill the pit of the mold.

Claims (17)

Ft grooved vision the surfaces of the network _{(25 i, 25 1 ',} 25 2') of the plate (24 _i) pit, jidoe is a compression plate (24 _i) made of a conductive material surface in (25 _i, 25 ₁ in ', 25 _2'), the micro lens manufacturing method of opening a network corresponds to the contour line projections of the micro-lens formed by permanently bending with respect to, Forming a group 9 _i consisting of a plurality of planar molds 25 _i , 25 ₁ ′, 25 ₂ ′ each having at least one non-conductive pit face, and a plurality of plates 24 _i made of a malleable material Wow; Inserting at least one of the mold between the plates (24 _i) such that at least one side is disposed opposite to the pit surface of the mold _{(25 i, 25 1 ',} 25 2') of each of the plates (24 _i); And And when the entire group has been produced, applying a uniform pressure to the group (9 _i ) in a direction perpendicular to the surface of the plate (24 _i ). 2. A method according to claim ₁ , which ensures isostatic pressing of the plate (24 _i ) and the mold (25 _i , 25 ₁ ', 25 ₂ ') group (9 _i ). The at least one mold (25 ₁ ) according to any one of the preceding claims, wherein the group is located between two plates (24 _i ) made of malleable material and printed with a pit network on two sides. ′, 25 ₂ ′) is derived. The method of claim 1, wherein at least one plate 24 _i of the group is positioned between two pit faces of two different molds 25 ₁ , 25 ₂ ; And the two faces coincide with each other, and after pressing, the two faces are aligned and arranged according to a mark for aligning the positions of the biconvex microlens networks. The pressure applied to the group is suitable for forming a microlens convex surface on the surface of the plate 24 _i , the plate being directed toward the pit surface of the mold without contact between the pit surface and the convex surface. Microlens network manufacturing method characterized in that. In a device comprising a heat insulating housing (1) and an inner space (3) heating means (2, 2 _j ) of the housing, a) a plurality of substantially planar molds 25 _i , 25 ₁ ′, 25 consisting of a plurality of plates 24 _i made of a malleable material under pressure at a temperature set by the heating means 2, 2 _j . ₂ ′), each mold comprising at least one non-conductive pit face under pressure at the temperature, wherein the molds 25 _i , 25 ₁ ′, 25 ₂ ′ are at least one side of each plate. Means (8) for supporting in the housing at least one group (9 _i ) inserted between the plates (24 _i ) so as to face towards the pit surface of the mold; b) when the group is created, further means (13,14,19,20,21) for providing a nearly uniform pressure on the entire group (9 _i ) facing perpendicular to the surface of the plate (24 _i ). Apparatus for implementing the method of claim 1 comprising a. 7. The mold according to claim 6, wherein the mold (25 _i , 25 ₁ ', 25 ₂ ') is thin in thickness so as not to severely disturb the transmission of pressure; Wherein the material forming the mold has mechanical properties that ensure local locality and relative position of the pit with respect to heat. 8. The bottom plate (13) according to claim 6 or 7, wherein said pressure providing means is designed to receive a plate (24 _i ) and a mold (25 _i , 25 ₁ ', 25 ₂ ') group 9 _i therebetween. And the mold 14, the power unit 20 which brings the bottom plate 13 close to the mold 14 when the group 9 _i is mounted between the bottom plate and the mold under isostatic pressing. Means (16,26) for assuring that it is to be ensured. 9. The device according to claim 8, wherein the means for placing under isostatic pressing comprises a sheet (26) made of a compressive material positioned between the mold (13) and the bottom plate (14) and the group (9 _i ). Device. 10. An apparatus according to claim 9, wherein said sheet (26) is made of graphite. 9. An apparatus according to claim 8, wherein the means for positioning under isostatic pressing comprises means for connecting a mold (14) or a bottom plate (13) around an axis perpendicular to the direction in which the pressure is applied. 7. Device according to claim 6, characterized in that it comprises delivery means (33,34,35) for automatically loading and discharging the device. 13. Apparatus according to claim 12, characterized in that the apparatus further comprises means for automatically producing a group (9 _i ) and means for automatically extracting the pit network formed after compression. 7. A plate (10) according to claim 6, wherein said means (13,14,19,20,21) is a plate facing the pit surface of the mold (25 _i , 25 ₁ ', 25 ₂ ') without contacting the surface of the pit with the convex surface. 24 _i ) pressure to create a microlens convex surface. 7. The apparatus according to claim 6, wherein the device is provided with a means for vacuum forming in the space (3) and a pressure suitable for completely filling the pits of the molds (25 _i , 25 ₁ ', 25 ₂ ') with the material of the plate. Means (13,14,19,20,21) for applying to said plate (24 _i ). 7. Device according to claim 6, characterized in that an intermediate sheet (27) is inserted into the group of plates (9 _i ) to prevent two neighboring plates (24 _i ) from adhering to each other. Microlens network obtained through the device according to any one of claims 6, 7 and 9-15.