TWI445615B - Press molding method for making lens array - Google Patents

Description

Method of imprinting a lens array

The present invention relates to the field of manufacturing optical components, and more particularly to a method of embossing a lens array.

Use thermosetting plastics, such as phenolic plastics, aminoplasts, unsaturated polyester plastics, polyimides, etc. to make lenses, especially one-time manufacturing of a large number of small lenses suitable for mounting on portable electronic devices. In the following manner, please refer to FIG. 1: A substrate 10, a mold core 11, is provided. The mold core 11 has a replica structure 110, and the replica structure 110 has a concave shape. First, the molding material 12 is coated on the substrate 10, the mold core 11 is pressed onto the molding material 12, the molding material 12 is heated to be flow-formed, and the cavity formed by the entire replica structure 110 and the substrate 10 is filled and then cured. Transformed into a convex lens.

The disadvantage of this method is that it is not easy to obtain a plastic product with a precise size, especially the thickness of a thick portion is inaccurate, because the thermosetting plastic has a shrinkage of about 5% during the imprinting process, and the thickness is higher. The more significant the effect of the thickness, the result is that the preform of the thermosetting plastic does not replicate the features of the replica structure of the mold, such as curvature, depth, etc., and therefore the accuracy in shape and size is low, if not in subsequent processing. Correction will affect the quality of the lens.

In view of this, it is necessary to provide an embossed lens array with high molding accuracy. The method.

A method of embossing a lens array, comprising the steps of: providing a substrate having a bearing surface; providing a mold core having an array of replica structures opposite the shape of the lens array, the replica structure array comprising a plurality of replica structures; coating a molding material on the bearing surface, the volume of the molding material being greater than a sum of volumes of all the lenses in the lens array; pressing the mold core to the molding material on the bearing surface to make the molding material According to the contour distribution of the replication structure; the molding material is initially pressurized, and the molding material is cured under a first temperature condition to form a preform close to the structure of the lens, and the molding material is shrunk so as to be in the mold a gap is formed between the kernel and the preform; the preform is again pressurized, and the first temperature is raised to a second temperature, and the preform is cured under the second temperature condition to further fill the molding material a gap; separating the mold core from the substrate to obtain a lens array.

The method for imprinting a lens array provided by the present invention reproduces the structure of the mold body by applying an excessive amount of the molding material and performing two pressurization on the molding material and curing at different temperatures, so that the formed lens array more accurately replicates the structure of the mold core. Features improve the precision of the molding and improve the quality of the lens.

10, 20, 40‧‧‧ substrates

11, 24, 44‧‧‧Men

12, 30, 50‧‧‧ molding materials

110, 260, 460‧‧‧ copy structure

21, 41‧‧‧ bearing surface

22‧‧‧ Groove

26, 46‧‧‧Copy Structure Array

27‧‧‧ Pressurized plate

29‧‧‧Flexible components

32‧‧‧Preforms

2‧‧‧ lens array

25‧‧‧ gap

FIG. 1 is a schematic view showing the effect of an embossed lens provided by the prior art.

2 is a perspective view of a substrate according to a first embodiment of the present invention.

3 is a schematic view showing the steps of curing a molding material under a first temperature condition according to a first embodiment of the present invention.

Figure 4 is a cross-sectional view of the pre-shaped body after contraction.

Figure 5 is a view showing the curing of the preform under the second temperature condition according to the first embodiment of the present invention. Step diagram.

FIG. 6 is a schematic perspective view of a convex lens array according to a first embodiment of the present invention.

Figure 7 is a schematic view showing the steps of curing a molding material under a first temperature condition according to a second embodiment of the present invention.

The invention will now be described in further detail with reference to the accompanying drawings.

Referring to FIG. 2 to FIG. 6 , the method for imprinting the lens array 2 provided by the embodiment of the present invention includes the following steps:

(1) A substrate 20 having a bearing surface 21 is provided.

The substrate 20 is a transparent substrate, for example, a substrate which has a diameter of 8 吋 (about 20.32 mm), but other sizes of substrates, such as 12 吋, may be used as long as the pressure applied thereto can be controlled uniformly. Just fine.

The bearing surface 21 is one surface of the substrate 20. Preferably, a plurality of grooves 22 are formed on the bearing surface 21, and the depth of the groove 22 is much smaller than the thickness of the substrate 20, which is used to define the molding position of each lens, and is convenient for subsequent dispensing or Quasi-equal action.

The groove 22 can be processed by etching, laser direct writing or the like.

(2) A mold core 24 is provided which has an array of replica structures 26 opposite the shape of the lens array 2.

The lens array 2 to be imprinted in this embodiment is a convex lens array. Thus, the replicated structure is a concave replica surface 260, and a plurality of concave replica surfaces 260 form a replica structure array 26.

(3) The molding material 30 is applied to the bearing surface 21, and the volume of the molding material 30 is larger than the sum of the volumes of all the lenses in the lens array.

Preferably, the molding material 30 is a thermosetting material such as phenolic plastic, aminoplast, unsaturated polyester plastic, polyimine, etc.; of course, it may also be a thermoplastic material.

The molding material 30 is melted and uniformly applied to the bearing surface 21 by spin coating or inkjet method. Note that even if the bearing surface 21 has the recess 22, uniform coating of the molding material 30 is not hindered because the depth of the recess 22 is small enough to affect the fluidity of the molding material 30.

Of course, the molding material 30 can also be applied to each molding position by dispensing, and if there is a groove 22, it is coated in the groove 22.

Whether it is the above uniform coating or spot coating, the volume of the molding material 30 is estimated in advance. The total volume of the molding material 30 is greater than the sum of the volumes of all the lenses in the lens array 2 to be formed.

Specifically, if the volume of each lens is required to be V, and there are n lenses in the entire lens array 2, the volume of the molding material required is nV, and the volume of the molding material 30 is larger than nV; if point coating is used, The volume of the molding material applied at each molding position is greater than V.

Generally, the excess volume range of the molding material is estimated based on the shrinkage ratio of the molding material itself. For example, when the shrinkage ratio of the molding material is about 6%, the volume of the molding material 30 is at least 10% larger than the sum of the volumes of all the lenses in the lens array 2. In addition, in consideration of the material overflow during the extrusion process, an excess volume is added to the excess of the molding material, for example, an additional 1% by volume of the molding material.

(4) pressing the mold core 24 against the molding material 30 on the bearing surface 21 to form the molding material The material 30 is distributed according to the contour of the replication structure 260.

The outline of the replica structure 260 is specifically a concave surface which may be a spherical concave surface or a non-spherical concave surface.

Note that a plurality of replica structures are provided on the entire mold core 24 to ensure an average pressure applied to the molding material at each molding position. The pressure plate 27 and the elastic member 29 between the pressure plate 27 and the mold core 24 can be used to accurately control the height of the plane of the mold core 24 and the strength of the depression.

Since the volume of the previously applied molding material 30 is larger than the sum of the volumes of all the lenses in the lens array, and the volume of the cavity formed by the replica structure 260 and the bearing surface 21 is smaller than the molding material applied at each molding position, Therefore, the replica structure 260 does not completely contain the molding material into the cavity, and the excess molding material 30 is filled around the periphery of the cavity, so that the die 24 cannot reach the bearing surface 21, so there is a gap between the two, but this The profile material is not hindered from filling the contour distribution of the entire replica structure 260.

(5) Referring to 3-4, the molding material 30 is initially pressurized, and the molding material 30 is cured under a first temperature condition, so that the molding material 30 forms a preform 32 close to the structure of the lens, and The molding material 30 is shrunk to create a gap 25 between the mold core and the preform 32, particularly in a thicker region, such as a central portion of the convex lens, the thickness of which is more conspicuous.

The pressure applied to the molding material 30 varies depending on the shape, material, and size of the molding structure. Generally, the unit pressure is several megapascals to several tens of megapascals.

After curing at the first temperature, the structure of the preform 32 is similar to the structure of the lens to be finalized.

Generally, the "first temperature" ranges between 50 degrees Celsius and 70 degrees Celsius.

The solidification at the first temperature causes the internal fluidity of the preform 32 to decrease, so that a partial region shrinks.

(6) The preform 32 is again pressurized to raise the first temperature to a second temperature, and the preform 32 is cured under the second temperature condition to further fill the gap 25 with the molding material 30.

Although some portions of the preform 32 are shrunk, the process of "repressurizing the preform 32 and curing the preform 32 at a second temperature condition" causes the preform 32 to re-enter the process of melt plasticization. The molding material which is still between the mold core 24 and the bearing surface 21 and does not completely enter the cavity is entered into the cavity due to the contraction and re-pressurization of the inner preform 32, and between the die 24 and the bearing surface 21 The gap 25 is further reduced or even absent. It should be noted that in actual production, some of the molding material may remain on the parting surface and become a flash. This is not shown in Figure 5.

Under the new conditions, the fluidity inside the preform 32 is further reduced until the effect of complete curing is achieved; moreover, since the preform 32 itself is formed by embossing a molding material having an excessive volume, the shrinkage rate has been estimated to be a molding material. The excess volume is considered, so that the volume of shrinkage caused by curing at the first temperature is corrected by the excess of the molding material at the second pressurization and the second temperature condition.

Typically, the pressure of the repressurization is greater than the pressure of the initial pressurization, and the "second temperature" ranges between 90 degrees Celsius and 110 degrees Celsius.

(7) The mold core 24 is separated from the substrate 20 to obtain a convex lens array 2.

Finally, the convex lens array 2 can be cut along the previously reserved scribe lines to obtain a separate convex lens.

The molding method provided by the embodiment more accurately replicates the structural features of the mold core 24, improves the precision of the molding, and improves the quality of the lens.

Referring to FIG. 7, a method of imprinting a lens array according to a second embodiment of the present invention manufactures a concave lens array.

Similar to the fabrication of the lenticular lens array 2, first, a substrate 40 having a bearing surface 41 is provided; a mold core 44 is provided, the mold core 44 having a replica structure array 46 opposite the shape of the concave lens array, the replica structure array 46 a plurality of replica structures 460 are included; a molding material 50 is coated on the bearing surface 41, the volume of the molding material 50 is greater than the sum of the volumes of all the concave lenses in the concave lens array; and the mold is closed, and the mold core 44 is pressed against the bearing surface. The molding material 50 on the 41 is such that the molding material 50 is distributed according to the contour of the replication structure 460; the molding material 50 is pressurized, and the molding material 50 is cured under the first temperature condition to cure the molding material 50. The structure of the concave lens is close to the preform, and shrinks in a thicker region, so that a gap is formed between the preform and the mold core 44; the preform is again pressurized, and the pressure of the repressurization is greater than the pressure of the first pressurization. And raising the first temperature to the second temperature and curing the preform under the second temperature condition; separating the mold core from the substrate to obtain a concave lens array.

In addition, it will be appreciated that the thicker regions of the concave lens are located outside of the center of the lens, particularly at the edge portions, so that shrinkage will occur in areas outside the center of the lens.

20‧‧‧Substrate

21‧‧‧ bearing surface

24‧‧‧Men

26‧‧‧Replicated Structure Array

260‧‧‧Copying structure

27‧‧‧ Pressurized plate

29‧‧‧Flexible components

30‧‧‧ molding materials

Claims (8)

A method of embossing a lens array, comprising the steps of: providing a substrate having a bearing surface; providing a mold core having an array of replica structures opposite the shape of the lens array, the replica structure array comprising a plurality of replica structures; coating a molding material on the bearing surface, the volume of the molding material being greater than a sum of volumes of all the lenses in the lens array; pressing the mold core to the molding material on the bearing surface to make the molding material According to the contour distribution of the replication structure; the molding material is initially pressurized, and the molding material is cured under a first temperature condition to form a preform close to the structure of the lens, and the molding material is shrunk so as to be in the mold a gap is formed between the kernel and the preform; the preform is again pressurized, and the first temperature is raised to a second temperature, and the preform is cured under the second temperature condition to further fill the molding material a gap; separating the mold core from the substrate to obtain a lens array. The method of imprinting a lens array according to claim 1, wherein: the volume of the molding material is at least 10% greater than the sum of the volumes of all the lenses in the lens array. The method of embossing a lens array according to claim 1, wherein: before the molding surface is coated with the molding material, a plurality of grooves are formed on the bearing surface, and each groove is used for defining a lens shape. position. The method of imprinting a lens array according to claim 1, wherein the first temperature ranges from 50 degrees Celsius to 70 degrees Celsius, and the second temperature ranges from 90 degrees Celsius to 110 degrees Celsius. The method of imprinting a lens array according to claim 4, wherein the molding material is a thermosetting material. The method of imprinting a lens array according to claim 1, wherein the lens array is a concave lens array. The method of imprinting a lens array according to claim 1, wherein the lens array is a convex lens array. The method of imprinting a lens array according to claim 1, wherein the pressure of the repressurization is greater than the pressure of the initial pressurization.