Process parameter optimization for lenses designed with microlenses

Abstract

Injection compression molding apparatus and method for forming a lens in a mold insert by injecting a polymer into an internal cavity of the mold insert until a pressure of the internal cavity exceeds a predetermined force value, a first mold side is stationary and a second mold side is movable and configured to apply the force that creates the internal cavity pressure. The method includes controlling a first temperature of the first mold side to be 4 to 10 degrees Fahrenheit higher than a second temperature of the second mold side and controlling a final press compression distance of the second mold side to be in a range of 0.008 to 0.018 inches.

Description

Technical Field

[0001] A temperature-controlled injection molding process for use in lens manufacturing environments. Background Technology

[0002] The "Background Art" section provided herein is intended to provide an overall overview of the context of this disclosure. The work of the currently nominated inventors, to the extent described in this Background Art section, and in aspects of this description that might not have been considered prior art at the time of submission, does not expressly or implicitly acknowledge that it is prior art to this disclosure.

[0003] In the manufacture of curved lenses, injection molding can be used, in which the mold insert is compressed when material (e.g., plastic) is injected into the mold. However, in order to form microstructures (such as microlenses) on the surface of the lens, the temperature of the insert must be strictly controlled when it is under high compressive force. Summary of the Invention

[0004] This disclosure relates to a method for injection compression molding a lens in a mold insert, the mold insert including an internal cavity, sidewalls, and a gate. The method includes: injecting a polymer via the gate into the internal cavity of the mold insert, formed by a coupled first mold side and a second mold side, until the pressure in the internal cavity exceeds a predetermined force value, wherein the first mold side is fixed and the second mold side is movable and configured to apply a force that generates the internal cavity pressure; wherein the method further includes: controlling a first temperature on the first mold side to be 4 degrees Fahrenheit to 10 degrees Fahrenheit higher than a second temperature on the second mold side; and controlling the precision compression distance on the second mold side to be in the range of 0.008 inches to 0.018 inches. Advantageous aspects of the method according to this disclosure are disclosed in claims 2 to 7.

[0005] The method further includes controlling the temperature on the mold side by: allowing coolant to flow through a first coolant channel in the first mold side at a first temperature; and / or allowing coolant to flow through a second coolant channel in the second mold side at a second temperature. This disclosure also relates to an injection compression molding apparatus for forming lenses as disclosed in claim 8. Advantageous aspects of the injection compression molding apparatus for forming lenses according to this disclosure are disclosed in claims 9 to 13. This disclosure also relates to an injection compression molding system for forming lenses as disclosed in claim 14. Advantageous aspects of the injection compression molding system for forming lenses according to this disclosure are disclosed in claim 15.

[0006] It should be noted that this summary does not detail every feature and / or progressively novel aspect of this disclosure or the claimed invention. Rather, this summary provides only a preliminary discussion of different embodiments and corresponding novel points. For additional details and / or possible perspectives on the invention and embodiments, the reader may refer to the detailed description section of this disclosure and the corresponding drawings discussed further below. Attached Figure Description

[0007] To gain a more complete understanding of the descriptions and advantages provided herein, please refer now to the following brief description in conjunction with the accompanying drawings and detailed description, wherein the same reference numerals denote the same parts.

[0008] Figure 1A A block diagram depicting the general characteristics of an injection molding apparatus within the scope of this disclosure is provided.

[0009] Figure 1B A block diagram of the control system of an injection molding equipment within the scope of this disclosure is depicted.

[0010] Figure 2 A graph depicting the relationship between the surface radius of the base bend on side A of the mold insert within the scope of this disclosure and temperature is presented.

[0011] Figure 3 A graph depicting the relationship between the surface radius of the back curvature of the mold insert on side B and temperature is presented within the scope of this disclosure.

[0012] Figure 4 A graph depicting the global focal length versus temperature on both sides of the mold insert, A and B, within the scope of this disclosure. Detailed Implementation

[0013] Lenses with microstructures formed on their surface, such as microlenses (also called “small lenses”), can provide prescription correction through a single-vision zone and myopia correction through a series of ringed aspherical small lenses. This type of lens can generate a large number of signals to slow down the growth of the eye's axial length. The power of each ring can be designed to ensure that a certain amount of signal is always in front of the retina and follows its shape to achieve consistent myopia reduction. A non-limiting example of a lens with ringed aspherical small lenses is Stellest. TM Lens (see: "Essilor's Game-Changing Stellest") TMLensShown To Slow Down Myopia Progression in Children By More Than 60%, After One-Year Interim Clinical Trial [Essiloxane's epoch-making Stellest] TM "Lens, after a year-long interim clinical trial, has been shown to slow the progression of myopia in children by more than 60%", September 28, 2020; Newsletter, Essilor (which incorporates the full text of the article by reference).

[0014] For example, microlenses (such as those used with Stellest) TM During the manufacturing process of microstructures such as lens-associated microlenses, it is important to maintain and achieve an acceptable forward curvature design and target global power for the microlenses, while monitoring any potential deviations of the microlens array from acceptable standards to meet product specifications during and after the manufacturing process. Temperature control of the mold insert during injection molding is extremely important. However, previous work has not addressed the use of different temperatures for different areas of the mold insert.

[0015] This disclosure addresses shortcomings in the field, particularly with the solutions proposed in the claims.

[0016] In the following description, the drawings are not necessarily drawn to scale, and for clarity and conciseness or for informational purposes, certain features may be shown in a broad or schematic form. Furthermore, although various embodiments of manufacture and use are discussed in detail below, it should be understood that many inventive concepts, as described herein, can be embodied in a variety of contexts. The embodiments discussed herein are merely illustrative and do not limit the scope of the invention. It will also be apparent to those skilled in the art that all technical features defined relative to the method can be transposed individually or in combination to the device, and conversely, all technical features relative to the device can be transposed individually or in combination to the method.

[0017] The following disclosure provides numerous different variations or examples for achieving various features of the proposed subject matter. Specific examples of components and arrangements are described below to simplify this disclosure. These components and arrangements are merely examples and are not intended to be limiting, nor are they contingent on their ability to operate together in any arrangement. Unless otherwise indicated, the features and embodiments described herein can operate together in any arrangement. For example, forming a first feature on or on a second feature in the following description may include embodiments where the first and second features are in direct contact, and may also include embodiments where additional features can be formed between the first and second features, such that the first and second features are not in direct contact. Additionally, reference numerals and / or letters may be repeated in various examples throughout this disclosure. This repetition is for simplicity and clarity and does not in itself define the relationship between the various embodiments and / or configurations discussed. Furthermore, for ease of description, spatial relative terms such as “top,” “bottom,” “below,” “under,” “lower,” “above,” “upper,” etc., may be used herein to describe the relationship between one element or feature and another element(s) as shown in the figures. Spatial relative terms are intended to cover different orientations of the device during use or operation, in addition to the orientations depicted in the figures. The device of this invention can be oriented in other ways (rotated 90 degrees or otherwise) and the spatial relative descriptive terms used herein can also be interpreted accordingly.

[0018] For clarity, the order of discussion of the different steps described herein has been presented. Generally, these steps can be performed in any suitable order. Furthermore, although each of the different features, techniques, configurations, etc., herein may be discussed in different places within this disclosure, it is intended that each concept can be implemented independently of or in combination with each other. Accordingly, the invention can be practiced and observed in many different ways.

[0019] In this disclosure, the term "compression molding" refers to an injection compression molding process that expands injection molding capabilities by compressing an injection mold.

[0020] This disclosure describes a management system for injection molding process parameters (such as temperature, pressure, and precision pressing) during manufacturing that achieves both good forward curvature replication and a target average global focal length. These process parameters achieve acceptable forward curvature and global focal length for the microlens within the production capability value Cpk.

[0021] The mold insert has an anterior curvature and a posterior curvature, or base curve, which form the lens structure. The anterior curvature can include microlenses, such as those described above for, but not limited to, myopia correction. During pressure injection of resin (e.g., polycarbonate resin), half of the mold insert closes via mold locking. As the injection pressure increases and decreases, air is vented from the surface of the mold insert until the mold can be fully closed.

[0022] Unlike some other thermoplastics, polycarbonate can undergo significant plastic deformation without cracking or breaking. In a non-limiting example, the polycarbonate resin can be a mixture of polymers, such as polycarbonate, polycarbonate / copolyester blends, acrylic resins (e.g., PMMA), cyclic olefin copolymers, amorphous polyamides, polyesters, copolyesters, polyurethanes, etc. The resin can be manufactured according to color specifications, i.e., for use in tinted lenses. In another non-limiting example, the polycarbonate resin can be Teijin 1270ZT (see: Teijin Panlite 1250ZT, sold by Teijin Corporation, Osaka, Japan).

[0023] Semi-finished single vision (SFSV) lenses are lenses sold in bulk to opticians and eyewear manufacturers. The standard manufacturing parameters for SFSV lenses are relatively close to these parameters (i.e., temperature, pressure, and precision pressing), and they can potentially meet optical specifications (i.e., good forward curvature reproduction and target average global power), but the process stability and process capability (Cpk) may be lower than required for production needs. Cpk or Cp > 1.0 indicates good reproducibility.

[0024] Table 1 shows the manufacturing parameters for a standard SFSV lens.

[0025] Table 1. Standard process parameters for SFSV lenses

[0026]

[0027]

[0028]

[0029]

[0030] Experimental design (DoE) was conducted to determine the key process parameters affecting the base bend and the global focal length of the microlens.

[0031] Figure 1AThis is a general top sectional view depicting some features of an injection molding apparatus 100, which can be used, for example, to manufacture lenses. In this apparatus, during the injection and cooling of polycarbonate, a clamping mechanism compresses the surface of the mold insert. The clamping operation requires precise control of the clamping force. In in-mold clamping (IMC) operation, springs and shims provide movement, allowing the internal cavity of the mold insert to expand without opening the mold. This feature allows for improved replication of the front insert, typically a concave insert with microstructures (such as microlens designs) that will be replicated on the front surface of the lens. IMC helps to better replicate the concave insert design by generating additional force through the compression of the springs during the injection molding process. This force from the IMC imparts the clamping effect, improving the front curvature and the optical performance and replication of the microlens to achieve the lens's optical performance and global power.

[0032] Microstructures may include microlenses, or miniature lenses, or any other type of structure or element with a physical Z-deformation / height between 0.1 μm and 50 μm and a width / length between 0.5 μm and 1.5 mm. These structures preferably have a periodic or pseudo-periodic layout, but may also have random positions. Preferred layouts of the microstructures may include grids with a constant grid step size, honeycomb layouts, multiple concentric rings, or continuous structures, such as those without space between microstructures. These structures can provide wavefront modification in terms of intensity, curvature, or optical deviation, wherein the wavefront intensity is configured such that the structure can be absorbent and can locally absorb the wavefront intensity, ranging from 0% to 100%; the curvature is configured such that the structure can locally modify the wavefront curvature, ranging from + / -20 diopters; and the optical deviation is configured such that the structure can locally scatter light, with an angle ranging from + / -1° to + / -30°.

[0033] exist Figure 1A and Figure 1B In the diagram, sides A and B indicate the equipment associated with the mold inserts and the sides formed by mold plates 106 and 138. Mold plate 106 can be patterned according to a microstructure. An internal mold cavity 160 between side mold plate 106 (A-side) and side mold plate 138 (B-side) receives an injection of polycarbonate resin, which is injected from injection unit 150 through gate 152. Injection controller 154 controls the injection rate and injection pressure. Injection controller 154 includes a rate sensor and a pressure sensor for monitoring the injection rate and injection pressure. Injection unit 150 is connected to a resin reservoir, pressure lines, and a gas source. Injection unit 150 injects polycarbonate resin into internal mold cavity 160 through gate 152 at the injection rate and injection percentage set by injection controller 154. This injection controller may be a processing circuit system implemented by a CPU and memory.

[0034] The A-side mold plate 106 has an internal concave curved surface that forms the convex surface of the lens. The A-side of the mold is held in place within a cylindrical housing by a locking mechanism within the mold. A locking pin holds the A-side of the mold within the cylindrical housing and can be released to replace the A-side of the mold. The B-side mold plate 138 has a convex surface that forms the concave surface of the lens. Similarly, a locking pin holds the B-side of the mold within the cylindrical housing and can be released to replace the B-side of the mold. To release the lens, pressure is released from the movable B-side of the device.

[0035] like Figure 1A As shown, alignment post 134 is attached to springs 1401 and 1402, which are separated by a washer 142. Springs 1401 and 1402, along with washer 142, are attached to a cup retainer 136, which is operatively connected to an elbow body 130, which compresses the B-side mold plate 138 during in-mold compression (IMC) operation. As polycarbonate resin fills the lens cavity 160, springs 1401 and 1402 are compressed. As the polycarbonate material cures and shrinks, compression pressure is applied through the springs up to the B-side of the mold. The springs are compressed by the pressure generated during the injection cycle, at which point compression is performed to push the B-side of the mold back, thus providing the IMC operation that imparts the compression effect. Elbow body alignment post 164 is operatively connected to the elbow body 130 to guide the movement of the B-side mold plate 138 to achieve uniform compression. IMC support post 162 provides support and guidance to elbow body alignment post 164.

[0036] Even slight temperature variations in the mold insert during the molding process can affect lens quality. A temperature controller preheats the mold insert and maintains it at the set temperature by circulating coolant (water or oil) through the mold plate. Figure 1B As shown, coolant A can enter the first coolant line at 129, and / or coolant B can enter the second coolant line at 128. A first temperature controller A 126 monitors and controls the temperature of the coolant passing through the mold plate 106 on side A, and a second temperature controller B 124 monitors and controls the temperature passing through the mold plate 138 on side B. Temperature controllers A and B can be implemented in a single temperature controller. Alternatively, the temperature controller can control only one side. This control of the mold insert temperature results in smaller mold temperature variations and more stable molding.

[0037] Figure 2 The graph shows the relationship between the base bend surface radius of the mold plate on side A and the temperature (in Fahrenheit).

[0038] Figure 3The graph shows the relationship between the base bend surface radius of the B-side mold plate and temperature (Fahrenheit).

[0039] As in Figure 2 and Figure 3 As can be seen, the mold temperature on both the A-side mold plate and the B-side mold plate has a significant impact on the curvature of the front surface. Figure 2 and Figure 3 In both figures, the mold temperature on side B is 250 degrees Fahrenheit, and the precision pressing distance is 0.015 inches. A key result is that the temperature of the mold plate on side A should be 4 to 10 degrees Fahrenheit higher than that of the mold plate on side B, and this difference provides a crucial effect. The mold plate temperature on side A should preferably be in the range of 255 to 280 degrees Fahrenheit, but the range can be 240 to 280 degrees Fahrenheit. Most preferably, the temperature of the mold plate on side A should be 255 degrees Fahrenheit. The temperature of the mold plate on side B should preferably be in the range of 240 to 275 degrees Fahrenheit, more preferably in the range of 250 to 257 degrees Fahrenheit, and most preferably 250 degrees Fahrenheit.

[0040] Another important aspect is that fine pressing affects the average global microlensing (μL) deviation. Since there are a large number of microlenses on the lens surface, the average global microlensing deviation is calculated using the difference between the nominal expected global power of the microlenses and the measured value of the microlenses.

[0041] Figure 4 This is a graph showing the relationship between the average global microlens deviation (μL) (in diopters) and the B-side mold temperature. Specifically, it illustrates the interaction between the average global deviation and the B-side mold temperature at 250°F with precision presses of 0.013 inches (curve 380) and 0.017 inches (curve 382). If the precision and holding pressures are sufficiently high, such as 0.017 inches, the B-side mold temperature may not be as critical. However, if the precision and holding pressures decrease to the 0.013-inch range, the B-side mold temperature has a significant impact on the average global microlens deviation. Therefore, Figure 4 The results show the interaction between temperature and pressure, and the effects of temperature and pressure on the average global microlens deviation.

[0042] Lenses (such as Stellest) were developed through experimental design. TM The manufacturing process for the lens aims to achieve not only good front surface curvature but also global focal power of the microlens array to produce a lens that meets specifications. Experimental design indicates that mold temperature (on both side A and side B) plays a crucial role in achieving the lens's front curvature. For example... Figure 2 and Figure 3As shown, a higher temperature on side A and a lower temperature on side B of the mold resulted in a lens with a front curvature design closer to a radius of 167mm. Therefore, the process parameters need to be set so that the mold temperature on side A is 4 to 10 degrees Fahrenheit higher than that on side B. These results will help improve future lens production.

[0043] It has also been found that precision pressing during processing is a factor affecting the overall microlens focal length. For example, in Figure 4 As can be seen, higher precision pressure becomes more critical when the B-side mold temperature is below 250°F. Using a higher B-side mold temperature allows for the use of lower precision pressure. To minimize the deviation in the global focal length of the microlens, a higher precision pressure (0.017 inches) and a higher B-side mold temperature can be used. The precision pressure can range from 0.008 inches to 0.018 inches.

[0044] These process parameters are designed to guide injection molding production facilities in producing these specialized types of lenses (such as Stellest lenses). TM These specialized lenses, used in mass production environments, not only have a central forward curvature but also an array of microstructures, such as miniature lenses surrounding the central forward curvature.

[0045] This process will be implemented at the mass production facility for injection-molded ophthalmic lenses to support maintaining optical performance and global power compliance with specifications.

[0046] This process will be implemented at the mass production facility for injection-molded ophthalmic lenses to achieve good reproducibility by maintaining a production process capability value Cpk or Cp > 1.0.

[0047] This set of process parameters can be used to help manage more stringent specifications for optical performance / global focal length in future products.

[0048] If the manufacturing symbol of the insert is given specifications, then the development process parameters shown in Table 2 will achieve a lens that meets the optical performance and global power specifications.

[0049] Table 2-3.25B SFSV Optimal Molding Parameters

[0050]

[0051]

[0052] When inserts undergo mass production and exhibit physical wear, areas requiring improvement may include adjustments to process parameters. The design of experimental results can help identify which key factors can be potentially used and adjusted to produce lenses from worn inserts that still meet optical performance and microlens global power specifications.

[0053] Because the lens design consists of SFSV forward curvature and a microlens array designed around the center of the sphere, the standard SFSV process conditions shown in Table 1 have been considered for lens production.

[0054] In the foregoing description, specific details, such as the particular geometry of the injection molding system and the description of the various components and processes used therein, have been set forth. However, it should be understood that the techniques described herein can be practiced in other embodiments departing from these specific details, and such details are for illustrative purposes rather than limiting. The embodiments disclosed herein have been described with reference to the accompanying drawings. Similarly, specific figures, materials, and configurations have been set forth for illustrative purposes to provide a thorough understanding. However, embodiments can be practiced without such specific details. Components having substantially the same functional structure are denoted by the same reference numerals, and therefore any redundant description may be omitted.

[0055] Various techniques have been described as multiple discrete operations to aid in understanding the various embodiments. The order of the descriptions should not be construed as implying that these operations necessarily depend on a specific order. In fact, these operations do not need to be performed in the order presented. Unless otherwise expressly indicated, the described operations may be performed in a different order than specifically described. Various additional operations may be performed and / or the described operations may be omitted.

[0056] Those skilled in the art will also understand that many variations can be made to the operation of the above-described techniques while still achieving the same objectives of the invention. Such variations are intended to be covered by the scope of this disclosure. Therefore, the foregoing description of embodiments of the invention is not intended to be restrictive. Rather, any limitations on embodiments of the invention are set forth in the following claims.

[0057] Embodiments of this disclosure may also be described as follows (1) A method for injection compression molding a lens in a mold insert, the mold insert including an internal cavity 160, a sidewall 108, and a gate 152, the method comprising: injecting a polymer via the gate into the internal cavity of the mold insert formed by a coupled first mold side 106 and a second mold side 138 until the pressure in the internal cavity exceeds a predetermined force value, wherein the first mold side is fixed and the second mold side is movable and configured to apply a force that generates the pressure in the internal cavity; and wherein the method further comprises: controlling a first temperature of the first mold side to be 4 degrees Fahrenheit to 10 degrees Fahrenheit higher than a second temperature of the second mold side; and controlling a precision compression distance of the second mold side to be in the range of 0.008 inches to 0.018 inches.

[0058] (2) The method as described in (1) further includes: controlling a first temperature on the first mold side preferably in the range of 245 degrees Fahrenheit to 280 degrees Fahrenheit, more preferably in the range of 250 degrees Fahrenheit to 263 degrees Fahrenheit, and most preferably 255 degrees Fahrenheit; and controlling a second temperature on the second mold side preferably in the range of 240 degrees Fahrenheit to 275 degrees Fahrenheit, more preferably in the range of 250 degrees Fahrenheit to 257 degrees Fahrenheit, and most preferably 250 degrees Fahrenheit.

[0059] (3) The method as described in any one of (1) or (2), wherein the precision compression distance on the second mold side is negatively correlated with the second temperature on the second mold side. (e.g.) Figure 4 As shown, curve 380)

[0060] (4) The method of any one of (1) to (3) wherein the coolant flows through a first coolant channel in the first mold side at the first temperature; and the coolant flows through a second coolant channel in the second mold side at the second temperature.

[0061] (5) The method of any one of (1) to (4) further includes: selecting the predetermined force value, preferably in the range of 9,000 psi to 15,000 psi, more preferably in the range of 10,000 psi to 13,000 psi, and most preferably 12,000 psi.

[0062] (6) The method of any one of (1) to (5) further includes: injecting the polymer for an injection time of 20 to 80 seconds, preferably 52 seconds; and cooling the polymer for a cooling time of 200 to 260 seconds, preferably 240 seconds.

[0063] (7) The method of any one of (1) to (6) further includes: injecting and cooling the polymer in the internal cavity for an injection cycle time of 220 seconds to 330 seconds, preferably 315 seconds.

[0064] (8) An injection compression molding apparatus 100 for forming lenses, comprising: a mold insert having a first mold side 106, a second mold side 138, and an internal cavity 160 formed between the first mold side and the second mold side, the first mold side being fixed and the second mold side being movable; a gate 152 connected to the internal cavity; an injection unit 150 connected to the gate and configured to inject polymer into the internal cavity 160; coolant channels in the first mold side 106 and / or the second mold side 138; a temperature controller circuitry 126 connected to the coolant channels and configured to control the temperature of the coolant in the coolant channels; springs and washers configured to control a precision compression distance of the second mold side within the range of 0.008 inches to 0.018 inches.

[0065] (9) The injection compression molding apparatus as described in (8) further includes: a set of springs (1401, 1402) and metal gaskets (142), the set of springs and metal gaskets being enclosed by a cup retainer (136) and connected to a movable side of the mold via an elbow body.

[0066] (10) An injection compression molding apparatus as described in any one of (8) or (9), wherein the polymer is a polycarbonate resin.

[0067] (11) The injection compression molding apparatus of any one of (8) to (10) further includes: an injection pressure sensor connected to the internal cavity such that the injection pressure sensor is configured to measure the internal cavity pressure; and wherein the injection unit is configured to inject the polymer into the internal cavity until the internal cavity pressure exceeds a predetermined force value.

[0068] (12) The injection compression molding apparatus of any one of (8) to (11) further comprises: an injection controller configured to select the predetermined force value, preferably in the range of 9,000 psi to 15,000 psi, more preferably in the range of 10,000 psi to 13,000 psi, and most preferably 12,000 psi.

[0069] (13) The injection compression molding apparatus as described in any one of (8) to (12), wherein the coolant channel serves as a first coolant channel 129 in the first mold side 106 and as a second coolant channel 128 in the second mold side 138, and the first coolant channel has a first coolant 122 and the second coolant channel has a second coolant 120, the temperature controller circuitry is configured to control a first temperature of the first coolant 122 preferably in the range of 245 degrees Fahrenheit to 280 degrees Fahrenheit, more preferably in the range of 250 degrees Fahrenheit to 265 degrees Fahrenheit, and most preferably 255 degrees Fahrenheit; and the temperature controller is configured to control a second temperature of the second coolant 120 preferably in the range of 240 degrees Fahrenheit to 280 degrees Fahrenheit, more preferably in the range of 250 degrees Fahrenheit to 257 degrees Fahrenheit, and most preferably 250 degrees Fahrenheit.

[0070] (14) An injection compression molding system for forming lenses, comprising: a mold insert having a first mold side 106, a second mold side 138, and an internal cavity 160 formed between the first mold side and the second mold side, the first mold side being fixed and the second mold side being configured to be movable; an injection unit 150 configured to inject a polymer into the internal cavity; a temperature controller connected to the first mold side and the second mold side, wherein the temperature controller is configured to control a first temperature of the first mold side and a second temperature of the second mold side, wherein the first temperature is 4 degrees Fahrenheit to 10 degrees Fahrenheit higher than the second temperature; and spring and washer bodies configured to control a precision compression distance of the second mold side in the range of 0.008 inches to 0.018 inches.

[0071] (15) The injection compression molding system as described in (14), wherein the temperature controller is configured to control a first temperature of the first coolant (122) preferably in the range of 245 degrees Fahrenheit to 280 degrees Fahrenheit, more preferably in the range of 250 degrees Fahrenheit to 263 degrees Fahrenheit, and most preferably 255 degrees Fahrenheit; and the temperature controller is configured to control a second temperature of the second coolant 120 preferably in the range of 240 degrees Fahrenheit to 275 degrees Fahrenheit, more preferably in the range of 250 degrees Fahrenheit to 257 degrees Fahrenheit, and most preferably 250 degrees Fahrenheit.

[0072] Although representative methods and articles have been described in detail herein, those skilled in the art will recognize that various alternatives and modifications can be made without departing from the scope described and defined by the appended claims.

Claims

1. A method for injection compression molding a lens in a mold insert, the mold insert comprising an internal cavity (160), sidewalls (108), and a gate (152), the method comprising: The polymer is injected via the gate into the internal cavity of the mold insert, which is formed by a first mold side (106) and a second mold side (138) connected according to a microstructure pattern, until the pressure in the internal cavity exceeds a predetermined force value. The first mold side is fixed, and the second mold side is movable and configured to apply a force that generates the pressure in the internal cavity. and The method further includes: controlling a first temperature on the first mold side patterned according to the microstructure to be 4 to 10 degrees Fahrenheit higher than a second temperature on the second mold side; and controlling the precision compression distance on the second mold side to be in the range of 0.008 inches to 0.018 inches.

2. The method of claim 1, further comprising: The first temperature on the first mold side is controlled within the range of 245 degrees Fahrenheit to 280 degrees Fahrenheit; as well as The second temperature on the second mold side is controlled within the range of 240 degrees Fahrenheit to 275 degrees Fahrenheit.

3. The method as described in claim 2, wherein, The precision compression distance on the second mold side is negatively correlated with the second temperature on the second mold side (138).

4. The method of claim 1, further comprising: The coolant flows through the first coolant channel in the first mold side (106) at the first temperature; as well as The coolant flows through the second coolant channel in the second mold side (138) at the second temperature.

5. The method of claim 1, further comprising: Select the predetermined force value within the range of 9,000 psi to 15,000 psi.

6. The method of claim 1, further comprising: The injection of the polymer lasts for an injection time ranging from 20 seconds to 80 seconds; as well as The cooling time of the polymer is in the range of 200 to 260 seconds.

7. The method of claim 1, further comprising: The injection cycle time for injecting and cooling the polymer in the internal cavity (160) is in the range of 220 to 330 seconds.

8. An injection compression molding apparatus (100) for shaping lenses, comprising: A mold insert having a first mold side (106), a second mold side (138), and an internal cavity (160), the first mold side being patterned according to a microstructure, the internal cavity being formed between the first mold side (106) and the second mold side (138), the first mold side (106) being fixed, and the second mold side (138) being movable; A gate (152) is connected to the internal cavity (160); An injection unit (150) is connected to the gate (152) and is configured to inject polymer into the internal cavity (160); Coolant channels in the first mold side (106) and / or the second mold side (138); A temperature controller circuit system (126) is connected to the coolant channel and configured to control the temperature of the coolant in the coolant channel such that a first temperature on the microstructure-patterned first mold side is within a range of 4 to 10 degrees Fahrenheit higher than a second temperature on the second mold side; and A spring and a washer are configured to control the precision compression distance of the second mold side (138) within the range of 0.008 inches to 0.018 inches.

9. The injection compression molding apparatus (100) as described in claim 8, further comprising: A set of springs (1401, 1402) is connected to the second side of the mold insert, wherein the set of springs (1401, 1402) is configured to control the tension and relaxation of the precision compression distance during the injection cycle.

10. The injection compression molding apparatus (100) as described in claim 8, wherein, The polymer is a polycarbonate resin.

11. The injection compression molding apparatus (100) as claimed in claim 8, further comprising: An injection pressure sensor is connected to the internal cavity (160) such that the injection pressure sensor is configured to measure the internal cavity pressure. and The injection unit is configured to inject the polymer into the internal cavity until the pressure in the internal cavity exceeds a predetermined force value.

12. The injection compression molding apparatus (100) as claimed in claim 11, further comprising: An injection controller configured to select the predetermined force value within the range of 9,000 psi to 15,000 psi.

13. The injection compression molding apparatus (100) as described in claim 8, wherein, The coolant channel serves as a first coolant channel (129) on the first mold side (106) and as a second coolant channel (128) on the second mold side (138), with the first coolant channel (129) containing a first coolant (122) and the second coolant channel (128) containing a second coolant (120). The temperature controller circuitry is configured to control the first temperature of the first coolant (122) within the range of 245 degrees Fahrenheit to 280 degrees Fahrenheit; and The temperature controller is configured to control the second temperature of the second coolant (120) within the range of 240 degrees Fahrenheit to 275 degrees Fahrenheit.

14. An injection compression molding system for shaping lenses, comprising: A mold insert having a first mold side (106), a second mold side (138), and an internal cavity (160), the first mold side being patterned according to a microstructure, the internal cavity being formed between the first mold side (106) and the second mold side (138), the first mold side (106) being fixed, and the second mold side (138) being configured to be movable; An injection unit (150) configured to inject polymer into the internal cavity (160); A temperature controller connected to the first mold side (106) and the second mold side (138), wherein the temperature controller is configured to control a first temperature of the first mold side (106) and a second temperature of the second mold side (138), wherein the first temperature is 4 to 10 degrees Fahrenheit higher than the second temperature; and A spring and a washer are configured to control the precision compression distance on the second mold side within the range of 0.008 inches to 0.018 inches.

15. The injection compression molding system of claim 14, wherein, The temperature controller is configured to control the first temperature of the first coolant (122) within the range of 245 degrees Fahrenheit to 280 degrees Fahrenheit; and The temperature controller is configured to control the second temperature of the second coolant (120) within the range of 240 degrees Fahrenheit to 275 degrees Fahrenheit.

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