Glass lens, method for manufacturing glass lens, and optical system

Abstract

A method for manufacturing a glass lens according to an embodiment of the present invention comprises the steps of: mixing glass particles, a polymer filled in between the glass particles, and an additive to provide a mixture; injection-molding the mixture by using a mold assembly having a lens shape; removing the polymer from a lens molded product injection-molded into the lens shape; sintering glass particles of the molded product removed of the polymer; and processing the sintered molded product to provide a glass lens, wherein at least one of the object-side surface or the sensor-side surface of the glass lens may have a critical point.

Description

Glass lens, glass lens manufacturing method and optical system

[0001] Embodiments of the invention relate to a glass lens and a method for manufacturing the same. Embodiments of the invention relate to an optical system having a glass lens.

[0002] Glass is transparent, strong, and has excellent thermal and chemical stability, making it a versatile material for a wide range of industries, including glass windows, solar panels, optical lenses, medical devices, and chemical and life science applications. In the field of optical lenses, glass offers significant advantages, including a wide refractive index range, low thermal expansion, and excellent durability. When processing glass optical lenses, pressure is applied to the glass at high temperatures to form it into the desired shape or it is processed using a grinder. However, glass has a melting point of approximately 1700 degrees Celsius, which affects the lifespan of the mold when melted and processed. Furthermore, its high durability makes physical forming difficult. These conventional techniques are unsuitable for mass production and are problematic due to the high processing costs.

[0003] Embodiments of the invention provide a glass lens comprising a glass material mixed with a polymer and an additive, and a method for manufacturing the same. Embodiments of the invention also provide a method for manufacturing a glass lens comprising a glass material mixed with a polymer and an additive, injection-molding the material through a heat treatment process, degreasing the polymer within the molded material, and then molding the glass lens. Embodiments of the invention can provide an optical system comprising a glass lens having a critical point.

[0004] An embodiment of the invention provides a method for manufacturing a glass lens, comprising the steps of: providing a mixture by mixing glass particles, a polymer filled between the glass particles, and an additive; injection-molding the mixture by a mold assembly having a lens shape; degreasing the polymer from a lens molded article injection-molded into the lens shape; sintering glass particles of the molded article from which the polymer has been degreasing; and processing the sintered molded article to provide a glass lens, wherein at least one of an object-side surface and a sensor-side surface of the glass lens may have a critical point.

[0005] According to an embodiment of the invention, the temperature for injection molding the molded article may be lower than the temperature for debinding the polymer. The sintering temperature of the glass particles may be higher than the temperature for debinding the polymer and the temperature for injection molding the molded article. The glass particles may include silica particles, and the polymer may include a thermoplastic resin material. Each of the glass particles has a size ranging from 10 nm to 500 nm, and the glass particles may be mixed in an amount of 40 wt% to 60 wt% with respect to the mixed material.

[0006] According to an embodiment of the invention, the mold assembly may have multiple gates to allow the mixture to be injected into the inner cavity.

[0007] A glass lens according to an embodiment of the invention comprises: glass particles; and a glass lens having a mixed material filled between the glass particles and having a refractive index different from that of the glass particles, wherein at least one of an object-side surface and a sensor-side surface of the glass lens has a critical point, and the glass lens may have cut surfaces arranged on the outside symmetrically to each other. According to an embodiment of the invention, the number of cut surfaces may be in the range of 2 to 4.

[0008] An optical system according to an embodiment of the invention comprises a plurality of lenses aligned along an optical axis from an object toward an image sensor, wherein at least one of the object-side lens and the last lens among the plurality of lenses is a glass lens as disclosed above, and the glass lens may be disposed at a position closest to the image sensor or at a position closest to the object.

[0009] According to embodiments of the invention, since the injection molding process of plastic lenses is utilized to manufacture glass lenses, limitations in processing shapes can be reduced. Specifically, the injection molding temperature of glass lenses can be low, manufacturing time can be shortened, mass production can be facilitated, and production and processing costs can be reduced. Furthermore, since the invention manufactures glass lenses based on a plastic injection process, it has the advantage of being easy to process critical points, spherical surfaces, aspherical surfaces, and free-form shapes depending on the shape of the injection mold. Furthermore, by forming critical points on the surface of the effective area of ​​the glass lens, changes in the optical path can be introduced.

[0010] By injection molding glass lenses, sintering times can be reduced. Specifically, the sintering process utilizes low-pressure spark plasma, reducing sintering time to approximately 30 minutes. This reduces manufacturing costs and improves productivity for glass lenses.

[0011] Embodiments of the invention can enhance the price competitiveness of materials for optical lenses or glass lenses produced therefrom, and improve the reliability of the glass lenses. Embodiments of the invention can provide glass lenses having a critical point, thereby improving the thermal and optical reliability of an optical system.

[0012] FIG. 1 is a schematic drawing showing a lens manufacturing process using a glass material according to an embodiment of the invention.

[0013] FIG. 2 is a drawing showing a lens manufacturing process using a glass lens material according to an embodiment of the invention.

[0014] Figure 3 is a flowchart showing the manufacturing process of the glass lens of Figure 2.

[0015] FIG. 4 is a drawing illustrating a process of manufacturing a glass lens using a mold assembly according to an embodiment of the invention.

[0016] Fig. 5 is a drawing illustrating an example of processing a lens from the shape of a glass lens manufactured by Fig. 4.

[0017] FIG. 6 is an example of a side cross-section of a glass lens having a critical point according to an embodiment of the invention.

[0018] Figures 7 (A)(B)(C) are drawings showing examples of the manufacturing process of the glass lens of Figure 6.

[0019] Fig. 8 (A) is a cross-sectional side view of a glass lens manufactured by Fig. 7, and (B) is an example of a manufactured glass lens.

[0020] Figures 9 (A)-(D) are drawings showing examples of glass lenses having critical points.

[0021] FIG. 10(A)(B) are examples of core and valve connections having a single gate for manufacturing a glass lens of the invention.

[0022] Figures 11(A)(B) are examples of core and valve connections having multiple gates for manufacturing a glass lens of the invention.

[0023] FIG. 12 is an example of a core having multiple gates and multiple cavities for manufacturing a glass lens of the invention.

[0024] FIG. 13 is an example of an optical system having a glass lens according to an embodiment of the invention.

[0025] FIG. 14 is another example of an optical system having a glass lens according to an embodiment of the invention.

[0026] Figure 15 is a graph comparing the sintering times of the lenses of the invention and comparative examples.

[0027] Hereinafter, preferred embodiments of the invention will be described in detail with reference to the attached drawings.

[0028] The technical idea of ​​the present invention is not limited to some of the embodiments described, but can be implemented in various different forms, and within the scope of the technical idea of ​​the present invention, one or more of the components between the embodiments can be selectively combined or substituted and used. In addition, the terms (including technical and scientific terms) used in the embodiments of the present invention can be interpreted as having a meaning that can be generally understood by a person of ordinary skill in the technical field to which the present invention belongs, unless explicitly and specifically defined and described, and the meaning of commonly used terms, such as terms defined in a dictionary, can be interpreted in consideration of the contextual meaning of the related technology. In addition, the terminology used in the embodiments of the present invention is for the purpose of describing the embodiments and is not intended to limit the present invention. In this specification, the singular may also include the plural unless specifically stated in the phrase, and when it is described as "A and (or at least one (or more than one) of B, C," it may include one or more of all combinations that can be combined with A, B, and C. In addition, when describing components of embodiments of the present invention, terms such as first, second, A, B, (a), (b), etc. may be used. These terms are only intended to distinguish the components from other components, and the nature, order, or sequence of the components are not determined by the terms. In addition, when it is described that a component is 'connected', 'coupled', or 'connected' to another component, the component may include not only cases where the component is directly connected, coupled, or connected to the other component, but also cases where the component is 'connected', 'coupled', or 'connected' by another component between the component and the other component.Additionally, when it is described as being formed or arranged "above or below" each component, "above" or "below" includes not only cases where the two components are in direct contact with each other, but also cases where one or more other components are formed or arranged between the two components. Furthermore, when it is expressed as "above" or "below", it can include the meaning of a downward direction as well as an upward direction based on one component.

[0029] FIG. 1 is a drawing schematically showing a process for manufacturing a lens using a glass material according to an embodiment of the invention, FIG. 2 is a drawing showing a process for manufacturing a lens using a glass lens material according to an embodiment of the invention, FIG. 3 is a flowchart showing a process for manufacturing a glass lens of FIG. 2, FIG. 4 is a drawing explaining a process for manufacturing a glass lens using a mold assembly according to an embodiment of the invention, and FIG. 5 is a drawing explaining an example of processing a lens from the shape of a glass lens manufactured by FIG. 4.

[0030] Referring to FIGS. 1 to 3, the material of the glass lens may be a mixture of glass particles (110) and at least one type of other material. The material of the glass lens includes a mixture, and may be, for example, glass particles (110) and at least one type of polymer (120) or a space from which the polymer (120) is removed. The mixture may be a space or a plastic material having a refractive index different from that of the glass particles (110) and may be a material that comes into contact with the glass particles (110). The material of the glass lens may include a mixture of the glass particles (110) and the polymer (120), and an additive (105). The additive (105) may be added for mixing and stability of the mixture. The material of the glass lens may include a material obtained by injection molding the mixture. The material of the glass lens may include a material obtained by degreasing or sintering the mixture after it has been injection molded. Here, the material of the glass lens may include a material having glass particles (110) and empty spaces between the glass particles from which the polymer (120) has been removed.

[0031]

[0032] The manufacturing process of the above glass lens may include a step (S1) of mixing materials of glass particles (110), polymer (120), and additive (105), a step (S3) of injection-molding the material mixed by the material mixing step (S1) into a lens shape, and a step (S6) of providing the material as a glass lens after the injection-molding step (S3). After the injection-molding step (S3) and before providing the lens, the process may further include a step (S4) of degreasing at least one material of the polymer (120) and additive (105), and a step (S5) of sintering the glass material molded product. Here, the temperature during the injection-molding may be a first temperature, the temperature during the degreasing may be a second temperature, and the temperature during the sintering may be a third temperature. The first temperature may be lower or higher than the second temperature, for example, may be lower than the second temperature. The third temperature may be higher than the first and second temperatures. The above first temperature may be a temperature range for plastic molding, and the above third temperature may be a temperature range for glass transition.

[0033]

[0034] In the material mixing step (S1), the glass particles (110) and the polymer (120) are mixed, and an additive (105) is added to the mixed material. The additive (105) can connect between the polymer (120) and the glass particles (110), between the polymers (120), and between the glass particles (110). The glass particles (110) are a transparent glass material, and the width or diameter of each particle is 800 nm or less, and may be in the range of, for example, 50 nm to 800 nm. The glass particles (110) may include spherical particles. As another example, the glass particles (110) may include at least one or both of spherical particles and irregular particles. Depending on the size and shape of the glass particles (110), the change in the shrinkage ratio of the glass lens can be controlled or selected.

[0035] The above glass material can be used as a base for manufacturing a quartz material lens using silica particles (SiO2). As another example, the particles can use other transparent materials that can determine the refractive index and Abbe number of the glass material. For example, when applying a borosilicate glass lens, the glass particles can include a composition of 80.6 wt% silica (SiO2), 13 wt% boron oxide (B2O3), 4 wt% sodium oxide (Na2O), and 2.3 wt% alumina (Al2O3). In order to manufacture a glass lens of a high refractive index material, the glass particles can include a material to which an oxidized heavy metal, such as lanthanum oxide (La2O3) or titanium dioxide (TiO2), is added. Such a glass material can be applied as a material having various refractive indices, such as not only fused silica, but also lime soda glass, borosilicate glass, and aluminosilicate glass. Additionally, glass materials can be applied to various transparent glass materials, such as glass containing heavy metals and glass with added oxides.

[0036] The polymer (120) may include a plastic material or a thermoplastic plastic resin. The polymer (120) may be nano-sized particles smaller than the size of the glass particles (110). As another example, the polymer (120) may be provided in the form of a solution. As another example, the polymer may include monomer particles instead of the polymer. The polymer (120) may be particles or a solution smaller than the glass particles (110) so as to fill the spaces between the glass particles (110). The size of the glass particles may be 500 nm or less, for example, 10 nm to 500 nm.

[0037] The type of polymer (120) or monomer that fills between and connects the glass particles (110) may be one or more, for example, a plurality of types of resins may be mixed. The polymer or monomer fills the empty space between the glass particles, and thereafter, a heat treatment or ultraviolet treatment process may be performed, or the glass particles may be more firmly fixed through an extrusion process (S2). Since the polymer (or monomer) exists between the glass particles, even if the glass particles are included, the mixed material may be provided as a polymer, i.e., a plastic material. The polymer (120) or monomer may include at least one of a material that can fill between the glass particles (110), for example, polyvinyl butyral, polyethylene glycol, 2-hydroxyethyl methacrylate, and 2-phenoxyethanol.

[0038]

[0039] The additive (105) of the glass lens material may include various materials such as a curing agent for polymerization and a linking agent for strong bonding between particles. The additive (105) may include at least one of 2,2'-Azobis(2-methylpropionitrile) and Tetra(ethylene glycol) diacrylate. The content of the glass particles (110) in the polymer (120) or mixed material may be mixed at 70 wt% or less, for example, 20 wt% to 70 wt% or 40 wt% to 60 wt%. That is, the mass ratio of the glass particles (110) in the mixture may be equal to or less than the mass of the polymer (120). Conversely, the mass ratio of the glass particles (110) in the mixture may be equal to or greater than the amount of the polymer (120). The content of the above glass particles (110) can be set by controlling the shrinkage rate of the final product, the isotropy of the shrinkage, and defects in the debinding and sintering processes. After mixing, the material may further include a liquid solvent, which may be removed through an oven process or at room temperature. If a material other than the glass material is not dried or removed, defects may occur in the debinding and sintering processes.

[0040]

[0041] After the above mixture is extruded (S2), the extruded mixture (112 in FIG. 1) is molded into an injection molded article having a lens shape (113A, 113B) at the same temperature as the injection molding temperature of the plastic material, and then, through a degreasing process (S3) and a sintering process, the polymer (120) present in the injection molded article (113 in FIG. 2) is degreasing through a degreasing process (S4), and the article (114 in FIG. 2) having an empty space (120A) from which the polymer has been removed can be provided as a lens molded article (115) made of glass material without an empty space inside through a sintering process.

[0042] The sintered material from which the polymer (120) has been removed can be provided as individual glass lenses through cutting and processing. The additive can be removed during the above process. That is, when the material for the glass lens is synthesized, the polymer (120) exists in the spaces between the glass particles (110) within the material, so that the injection molding process is performed in the shape of a lens at a temperature lower than the melting point of glass, 1700 degrees. In addition, the injection molded material undergoes a degreasing process at a temperature of 250 degrees or higher, for example, in the range of 250 to 700 degrees or in the range of 400 to 600 degrees. The degreasing process is a process of removing the polymer from between the molded glass particles. That is, the polymer (120) can react with oxygen in the air at about 300 degrees and be removed as a gas containing carbon dioxide.

[0043] The material from which the polymer (120) has been removed has glass particles in a lens shape, and empty spaces exist in the spaces where the polymer (120) has been removed. To remove these empty spaces, the molded product is sintered near the transition temperature of the glass material. At this time, the glass particles are melted by high-temperature energy, transition to a slightly viscous state, and combine with surrounding particles to fill the empty spaces. By removing the empty spaces between the glass particles through this sintering process and increasing the density of the glass material, the material becomes glassy and can be manufactured into glass having a lens shape.

[0044]

[0045] Hereinafter, the specific injection molding process, polymer debinding process, and sintering process will be described.

[0046] <Injection molding process of the mixture (S2)>

[0047] The monomer or polymer in the mixture (111 in FIG. 2) is cured. At this time, the mixture can be cured in various ways, such as with light or heat, depending on the additive (105). In addition, since the size of the mixture is greatly reduced after the degreasing and sintering processes, the size of the injection-molded mixture can be mixed and extruded to a larger size considering the shrinkage. The shrinkage of the mixture can occur in an isotropic or anisotropic shape depending on the shape, diameter, and thickness of the lens. The shape of the injection mold can be corrected to compensate for this shrinkage.

[0048] Conditions for injection molding of the above mixture, such as injection pressure, time, and temperature, can be adjusted depending on the polymer material added to the synthesis of the mixture. For example, the injection pressure for molding an injection-molded product can be within the range of 5 to 20 bar. The injection temperature can be within the range of 100 to 170 degrees. The time required for injection can be within the range of 4 to 15 seconds. Here, since the concentration of glass particles (110), i.e., silica particles, in the mixture changes the viscosity and elasticity of the polymer (120), the injection conditions can be adjusted within a reasonable range taking this into consideration.

[0049]

[0050] As shown in Fig. 4, the injection-molded mold assembly may include a first core (101) and a second core (102). The first and second cores (101, 102) may be made of a metal material capable of injection-molding a glass material. The second core (102) may include a mold (103) having a second cavity (R2). The mold (103) may be made of a metal material and faces the first core (101). The first core (101) has a plurality of first cavities (R1) spaced apart from each other in an area facing the mold (103), and the mold (103) may have a second cavity (R2) arranged in each area facing the first cavity (R1). The combined shape of the first and second cavities (R1, R2) can form a cavity having a lens shape to be manufactured. The lens shape can include at least one of a shape in which one surface of the lens is concave and the other surface is concave, a shape in which one surface is concave and the other surface is convex, a shape in which one surface is convex and the other surface is convex, or a shape in which one surface is convex and the other surface is concave. One surface of the lens can be an incident surface of light, and the other surface can be an exit surface of light. At least one of the one surface and the other surface can be a spherical surface. As another example, at least one of the one surface and the other surface can be an aspherical surface.

[0051] The number of cavities for lenses within the first and second cores (101, 102) may be one or more, but may include eight or twelve cavities, etc., to increase productivity. Considering the injection speed and pressure of the mixture filled in each cavity, the first and second cavities (R1, R2) may be provided in a symmetrical shape with respect to each other. The second core (102) is provided with a gate (105), and the gate (105) is provided in a size that allows nano glass particles to be introduced or a size that allows the mixture to be introduced, and the mixture can be injected through the gate (105). For the introduction of the mixture, a runner, which is a flow path between the first and second cores (101, 102), may have a size or diameter that does not affect the fluidity of the nano glass particles. When the mixture is filled in the cavities (R1, R2), an injection molded article (153) having a lens shape (151, 152) can be provided. The injected mixture is formed into a lens shape, and the shape is a shape in which a polymer is filled between glass particles. At this time, the lens shapes (151, 152) may be connected to each other by a connecting part (154). Here, the first core (101) may be a fixed part, and the second core (102) may be a moving part that is coupled to or separated from the first core (101). The extrusion process before the injection molding may be performed by injecting the mixture and then applying pressure through the gate (105) to extrude it. As another example, the mixture may be placed in the lower cavity, and then the upper core may be pressurized and injection molded.

[0052]

[0053] <Polymer degreasing process (S4)>

[0054] The injected mixture is formed into a lens shape, and the shape is such that the polymer is filled between the glass particles. In order to extract pure glass material, a polymer degreasing process (S4) is performed to remove the polymer (120) existing between the glass particles. The polymer degreasing process (S4) is performed by a high-temperature degreasing method after solvent degreasing depending on the type, particle size, and chemical properties of the polymer existing between the glass particles. The solvent degreasing method is a method of degreasing by slowly dissolving the polymer (120) in a solvent. The solvent for degreasing may include at least one of distilled water (H2O), ethanol (EtOH), and isopropyl alcohol (IPA), and may include all solvents that dissolve the polymer (120) slowly rather than rapidly. In addition, for efficient degreasing, the solvent degreasing temperature may be 50 degrees or less, for example, in the range of 30 to 50 degrees, and the degreasing time may be 10 hours or less, for example, 1 to 10 hours, depending on the type of polymer. Depending on the polymer type, solvent degreasing may be omitted to increase productivity efficiency.

[0055] After the solvent degreasing, the injection-molded article is completely dried to remove the solvent, and then high-temperature degreasing is performed. This is because if any solvent remains during the high-temperature degreasing process, defects may occur in the injection-molded article, and sudden solvent vaporization may cause the injection-molded article to explode. High-temperature degreasing is a process for removing polymers between glass particles from the injection-molded article at high temperatures. Most polymers can react with oxygen in the air and be removed as carbon dioxide gas within about 300 degrees Celsius. In addition, to completely remove organic substances in the injection-molded article, high-temperature degreasing is performed at about 500 degrees Celsius or higher, for example, in the range of 500 to 700 degrees Celsius, and degreasing may be performed in the range of 550 to 650 degrees Celsius. Here, rapid temperature control during heating for the degreasing process may cause defects in the injection-molded article. For example, a rapid temperature increase to the degreasing temperature may cause strong fluidity of the polymer between the glass particles or generate a large amount of gas, which may cause cracks. Accordingly, the heating and cooling speeds from room temperature to the degreasing temperature can be 20 degrees / minute or less, for example, in the range of 0.5 to 20 degrees / minute. The holding time at the temperature for degreasing can be 5 hours or less, for example, in the range of 1 to 5 hours.

[0056]

[0057] <Sintering process of the mixture (S5)>

[0058] The polymer-degreased injection-molded article is a shape in which only the glass particles remain, as the polymer between the glass particles has been removed. The empty spaces between the glass particles are defects that cause light scattering, so the shape after degreasing may be opaque even though only the glass particles remain. Accordingly, a high-temperature sintering process is performed (S5) to remove the empty spaces within the injection-molded article and increase the density of the injection-molded article. During the sintering process (S5), the glass particles become glassy and bond with each other. This fills the empty spaces between the glass particles to form perfect glass. The sintering temperature during the sintering process may be 1500 degrees Celsius or lower, for example, in the range of 1000 to 1500 degrees Celsius, depending on the material of the glass particles. The sintering temperature may be determined near the glass transition temperature of the material. For example, the sintering temperature for producing a quartz (SiO2) lens may be approximately 1300 degrees Celsius or 1250 to 1350 degrees Celsius.

[0059] In addition, the isothermal and cooling rates from room temperature to the sintering temperature can be 500 degrees / min or less, for example, in the range of 5 to 500 degrees / min. The holding time at the sintering temperature can be 3 hours or less, for example, in the range of 5 to 3 hours. In addition, when applying low-pressure spark plasma sintering technology (Pressure less SPS), the sintering time can be shortened to less than 1 hour, and can be carried out in 30 minutes or less as shown in (A) of Fig. 7. Although this may vary depending on the material, the sintering process can be carried out within 1 hour, which can reduce manufacturing costs and improve productivity. A comparative example such as (B) of Fig. 7 is sintered through an oven process, which takes about 10 hours, which can result in decreased productivity and increased manufacturing costs.

[0060]

[0061] During the above sintering process, the degree of crystallization of the glass may vary depending on the sintering temperature, holding time, heating and cooling rates. In order to manufacture transparent glass lenses, sintering conditions that suppress glass crystallization must be utilized. For example, low-pressure spark plasma sintering conditions for manufacturing lenses made of quartz (SiO2) may include a heating rate of 225 degrees / min, holding at 1300 degrees for 5 minutes, and a cooling rate of 60 degrees / min, and these conditions may vary depending on the material of the glass particles. In this sintering process (S5), voids within the lens molding are removed, resulting in shrinkage of the injection lens. Although compensation for shrinkage is performed within the injection mold, it can be compensated for by the surface shape of the first and second cores (101, 102) or the first core (101) and the mold (103) having a shape-retaining metal during the sintering process for isotropic shrinkage. The shape-retaining metal can maintain the shape of the injection-molded product during sintering, and can induce isotropic shrinkage through even heat transfer to the injection-molded product. One surface of the sintered lens may be a light incident surface, and the other surface may be a light exit surface. At least one of the one surface and the other surface may be a spherical surface. As another example, at least one of the one surface and the other surface may be an aspherical surface.

[0062] At least one of the surfaces of the first and second cores (101, 102) and the surface of the mold (103) may be provided in a shape having a critical point. In this case, the molded product of the manufactured glass lens may have a critical point. The refractive index of the glass lens may be 1.4 or higher, for example, in the range of 1.4 to 2.1 or in the range of 1.7 to 2.1.

[0063]

[0064] As shown in Fig. 5, the gate portion (153A) remaining in the molded article (153) having the lens shape (151, 152) can be cut and manufactured into an injection-molded article of an individual glass lens (150). The cutting of the gate portion (153A) can include various methods such as a high-temperature blade, laser cutting, or ultrasonic cutting to minimize changes in the lens shape. The connecting portion (154) remaining after injection can be used to extract glass material by removing the polymer with a specific solvent. That is, the glass particles can be recycled. Since the molding mold of the aspherical lens has an upper core and a lower core formed of a material with excellent moldability, it has the advantage of preventing wear of the grinding tool during mold manufacturing, thereby reducing the defect rate, and increasing the service life of the grinding tool. By forming a coating layer such as a mold on the surface of the first and second cores, it is possible to prevent the core from wearing out or being damaged, thereby increasing the service life of the core. Additionally, the temperature within the cavity proceeds at the injection molding temperature disclosed above, and the degreasing and sintering processes also proceed at the temperatures disclosed above. To this end, a heating unit (not shown) having a temperature sensor (not shown) is provided outside the mold assembly, and the measured temperature can be controlled through a control unit (not shown).

[0065]

[0066] Referring to FIGS. 6 to 8, the glass lens (250) may be formed using the glass material disclosed above. That is, the glass lens (250) is provided by an injection molding method using a composite of a polymer and glass particles, and may be provided as a glass lens of various shapes without any restrictions on the surface shape of the lens. The size of the glass particles may be 10 nm or more, for example, 10 nm to 500 nm.

[0067] The glass lens (250) has an object-side surface (S11) and a sensor-side surface (S12). The object-side surface (S11) is the surface opposite the sensor-side surface (S12) and is adjacent to the object. The sensor-side surface (S12) is the surface opposite the object-side surface (S11) and is adjacent to the image sensor. The centers of the object-side surface (S11) and the sensor-side surface (S12) of the glass lens (250) are aligned with the optical axis (OA). On the optical axis (OA), the object-side surface (S11) may have a convex shape, and the sensor-side surface (S12) may have a concave shape. As another example, on the optical axis (OA), the object-side surface (S11) may have a concave shape, and the sensor-side surface (S12) may have a convex shape. As another example, the object-side surface (S11) and the sensor-side surface (S12) on the optical axis may be provided in a convex shape. As another example, the object-side surface (S11) and the sensor-side surface (S12) on the optical axis may be provided in a concave shape.

[0068] The glass lens (250) may include an effective area and an ineffective area. The effective area may be an area through which incident light passes. That is, the effective area may be defined as an effective area or effective diameter through which incident light is refracted to implement optical characteristics. The ineffective area may be arranged around the periphery of the effective area. The ineffective area may be an area where effective light is not incident. That is, the ineffective area is an area unrelated to the optical characteristics and may be defined as a flange portion. In addition, an end of the ineffective area may be an area fixed to a lens barrel (not shown) that accommodates the lens(es). The outer side surface (S13) of the glass lens (250) may be provided as a vertical surface or an inclined surface and may be in contact with the lens barrel. The lens (250) may be provided without a ineffective area.

[0069]

[0070] At least one of the object-side surface (S11) and the sensor-side surface (S12) of the glass lens (250) may have at least one critical point or inflection point (hereinafter referred to as a critical point) between the optical axis and the end of the effective area. The critical point is a point where the sign of the slope value with respect to the direction perpendicular to the optical axis (OA) with respect to the optical axis changes from positive (+) to negative (-) or from negative (-) to positive (+), and may mean a point where the slope value is 0. In addition, the critical point may be a point where the slope value of a tangent line passing through the lens surface increases and then decreases, or decreases and then increases. The object-side surface (S11) of the glass lens (250) may have a first critical point and may change the light path that proceeds from the optical axis (OA) to the inner region between the first critical point (P1) and the sensor-side surface (S12) to the end of the effective area.

[0071] The sensor-side surface (S12) of the glass lens (250) has a second critical point (P2) and can change the light path that progresses from the optical axis (OA) to the inner region between the second critical point (P2) and the outer region between the end of the effective region and the second critical point (P2). Light incident on the inner region of the object-side surface (S11) by the first critical point (P1) is refracted toward the optical axis (OA), and light incident on the outer region can be refracted in a direction away from the optical axis (OA). In addition, light transmitted through the inner region of the sensor-side surface (S12) by the second critical point (P2) is refracted in the direction of the optical axis, and light incident on the outer region can be refracted in a direction away from the optical axis (OA). Accordingly, the gap between two adjacent lenses can be adjusted by the glass lens (250) having the critical points (P1, P2), and the effective diameter of the sensor-side lens arranged on the sensor side relative to the glass lens (250) can be increased or decreased. In addition, the effective diameter of the object-side lens arranged on the object side relative to the glass lens (250) or the gap between the lenses can be adjusted. The lens can be provided as a free-form lens in which the object-side surface (S11) and / or the sensor-side surface (S12) have critical points. Accordingly, the invention uses the glass lens (250) so that the object-side surface (S11) or the sensor-side surface (S12) can be provided in a convex or concave shape on the optical axis (OA), and can have at least one critical point (P1, P2).

[0072] The manufacturing process of the above glass lens will be described with reference to FIGS. 7 and 8. As shown in (A) and (B) of FIG. 7, the first core (201) and the second core (202) are placed opposite each other and then moved to adhere to each other. The first cavity (R11) of the first core (201) has a first surface (S21) corresponding to the shape of the object-side surface of the lens, and the second cavity (R12) of the second core (202) has a second surface (S22) corresponding to the shape of the sensor-side surface of the lens. The area of ​​the first and second cavities (R11, R12) can be defined as a cavity (R10) of the mold assembly. At least one or both of the first surface (S21) and the second surface (S22) can have a critical point. That is, the critical point may be a point where the concave surface changes to a convex surface or a point where the convex surface changes to a concave surface.

[0073] When the first and second cores (201, 202) are in close contact, gates (205, 206) are provided. The gates (205, 206) are connected to the cavity (R10) and may be provided one by one or in multiple numbers. The plurality of gates (205, 206) may be arranged on opposite sides of the cavity (R10) or in positions symmetrical to each other, in which case the injection efficiency of the glass lens material may be improved.

[0074] As shown in (B)(C) of Fig. 7, the glass lens material is injected into the cavity (R10) through the gates (205, 206). The gates (205, 206) are provided in a size that allows nano-sized glass particles or a size that allows a mixture to be injected, and the mixture can be injected through the gates (205, 206). The extrusion process before the injection molding can be performed by injecting the mixture and then applying pressure through the gates (205, 206) to extrude it. When the glass lens material is filled in the cavity (R10), the material of the glass lens (250A) has a shape in which polymers are filled between the glass particles. After the extruded glass lens material is injection molded (S3 of Fig. 3), the polymer is degreased from the injection molded material (S4 of Fig. 3), and the material from which the polymer is degreased is sintered (S5 of Fig. 3). Thereafter, as shown in (A) of Fig. 8, the gate protrusions (251, 252) remaining in the gate portion of the sintered glass lens (250A) are cut and removed, and a glass lens can be provided as shown in (B) of Fig. 8 (S6 of Fig. 3). Steps S3-S5 of Fig. 3 refer to the description disclosed above. The manufactured glass lens (250) may have a first critical point (P1) on the object-side surface (S11) and / or a second critical point (P2) on the sensor-side surface (S12). The positions of the first and second critical points (P1, P2) may be changed depending on the optical design.

[0075] The diameter of the glass lens (250) manufactured by the injection molding method disclosed above may be provided as 2 mm or more, for example, in a shape of 2 mm to 100 mm or in a range of 2 mm to 40 mm. The minimum center thickness of the glass lens (250) may be 0.1 mm or more, for example, in a range of 0.1 mm to 5 mm. The edge thickness or flange thickness of the glass lens may be 0.1 mm or more, for example, in a range of 0.1 mm to 5 mm. The glass lens (250) manufactured by the injection molding method disclosed above may have a surface roughness of 5 nm or more, for example, in a range of 5 nm to 15 nm. The surface of the glass lens (250) may be polished using various methods such as sandpaper or slurry to further improve the surface roughness.

[0076]

[0077] Depending on the shape of the first and second cores (201, 202) and the cavity (R10) of the mold assembly, various glass lens shapes can be provided. As shown in (A) of Fig. 9, the glass lens (230) may have a concave object-side surface (S31) on the optical axis (OA) and a convex sensor-side surface (S32). The object-side surface (S31) may have a first critical point (P3). As shown in (B) of Fig. 9, the glass lens (231) may have a concave object-side surface (S33) on the optical axis (OA) and a concave sensor-side surface (S34). The object-side surface (S33) may have a first critical point (P5) closer to the edge than the optical axis (OA). The sensor-side surface (S34) may have a second critical point (P6) closer to the optical axis (OA) than the first critical point (P5). As shown in (C) of Fig. 9, the glass lens (232) may have a convex object-side surface (S35) on the optical axis (OA) and a concave sensor-side surface (S36). The object-side surface (S35) may have a plurality of critical points, for example, a first-first critical point (P7A) and a first-second critical point (P7B). The sensor-side surface (S36) may have a second critical point (P8). The first-first critical point (P7A) may be arranged at a position corresponding to the second critical point (P8) in the optical axis direction or may be arranged further adjacent to the optical axis (OA).

[0078] As shown in (D) of Fig. 9, the glass lens (233) may have a concave object-side surface (S37) on the optical axis (OA) and a convex sensor-side surface (S38). The object-side surface (S37) may have a critical point (P9) adjacent to the optical axis (OA). The sensor-side surface (S38) may be provided without a critical point from the optical axis (OA) to the edge.

[0079]

[0080] As shown in Fig. 10, the mold assembly (200) having the first and second cores has a cavity (250B) or a lens region therein, a single gate (212) is connected, and the gate (212) is connected to a supply valve (215) through a runner (211). As shown in Fig. 11, the mold assembly (200) having the first and second cores has a cavity (250B) or a lens region therein, a plurality of gates (212) are connected, and each of the plurality of gates (212) is connected to a supply valve (215) through a runner (211). Each of the mold assemblies (200) can be connected to the cavity (250B) through two gates (212) located on opposite sides. As shown in (A)(B) of Fig. 12, a plurality of mold assemblies (200) having first and second cores have cavities (250B) or lens regions therein, and a plurality of gates (212) are connected, and each of the plurality of gates (212) is connected to a supply valve (215) through a runner (211). Each of the mold assemblies (200) can be connected to the cavity (250B) by four gates (212).

[0081] In order to uniformly distribute the glass particles and polymer injected into the cavity (250B), two, three, or four or more gates may be connected along the periphery of the cavity (250B). That is, one or more gates, for example, one to eight, for forming a glass lens may be connected to the cavity (250B). The positions of the two or more multiple gates may be arranged symmetrically or asymmetrically so as to uniformly fill the distribution of the glass particles according to the lens shape. The diameter of the multiple gates (211) is adjusted according to the flowability of the raw material composite, and preferably includes a range of 0.1 mm or more, for example, 0.1 mm to 2 mm. The shape of the gates (211) may include any one of a circle, a square, a rectangle, and a trapezoidal shape depending on the properties of the composite.

[0082] The mold assembly for injection molding the above glass lens may be applied with gates such as ring, tab, side, overlap, disk, edge, and pin point to ensure uniform filling of glass particle powder, and open, valve, and semi-valve gates of a heart runner system may be applied to consider the shrinkage of the glass lens product. In addition, a gate system having multiple mold assemblies may be applied with multiple cavities, preferably at least 4, for example, 4 to 24 cavities, so as to ensure uniform filling of the distribution of glass particles. In addition, the gate protrusion remaining on the glass lens due to the gate may be provided as a lens removed mechanically, chemically, or optically. For example, the gate protrusion can be removed physically with a high-temperature blade, or can be removed through etching using a chemical agent. In addition, the gate can be removed using a high-power laser. After the gate is removed, the shape of the side surface (i.e., the cut surface) of the lens may have various shapes such as a D-cut shape, a double D-cut shape, a square-cut shape, etc. The glass lens of the invention may have two to four multiple cutting surfaces. The number of cutting surfaces may be equal to the number of gates. Previously, it was difficult to compensate for the lens surface having a critical point due to shrinkage during injection molding of glass lenses, making it difficult to implement. The invention solves the above-mentioned problem and provides a glass lens having a lens surface having a critical point. Since the invention molds the shape of a glass lens through injection molding using a polymer-glass particle composite, it can be molded into various lens surfaces, such as a critical point, a spherical surface, an aspherical surface, a spherical surface or an aspherical surface having a critical point, etc. The glass lens has little change in temperature, so it is used in highly reliable vehicle camera modules, military optical equipment, precision microscopes, or telescopes. The invention provides various shapes of glass lenses that were previously impossible to manufacture, so it can be used in the field of highly reliable precision optics.

[0083]

[0084] Fig. 13 is a drawing showing an example of an optical system having a glass lens of the invention.

[0085] As shown in Fig. 13, the optical system may include a plurality of lenses aligned along the optical axis (OA) from the object toward the image sensor (266). The number of the plurality of lenses may be three, four, or five or more. The plurality of lenses may be first to fourth lenses (261, 262, 263, and 264). The first lens (261) is closest to the object and may have a convex object-side surface and a convex sensor-side surface on the optical axis (OA). The second lens (262) is disposed between the first lens (261) and the third lens (263) and may have a concave object-side surface and a concave sensor-side surface on the optical axis (OA). The third lens (263) is disposed between the second lens (262) and the fourth lens (264) and may have a convex object-side surface and a convex sensor-side surface on the optical axis (OA). The object-side surface and the sensor-side surface of the first to third lenses (261, 262, 263) may be provided in different shapes. At least one or all of the first to third lenses (261, 262, 263) may be made of plastic or glass.

[0086] An aperture (ST) may be placed on the periphery between the second lens (262) and the third lens (263). The aperture (ST) may control the amount of light incident on the third lens (263).

[0087] The fourth lens (264) may be arranged between the third lens (263) and the image sensor (266). The fourth lens (264) may include a convex object-side surface (S41) and a concave sensor-side surface (S42) on the optical axis (OA). The object-side surface (S41) may have a first critical point (P11), and the sensor-side surface (S42) may have a second critical point (P12). The fourth lens (264) may refract light incident through the critical points (P11, P12) to the center and periphery of the image sensor (266). Accordingly, the resolution of the optical system may be improved.

[0088] The optical system may include an optical filter (not shown). The optical filter may be disposed between the fourth lens (264) and the image sensor (266). The optical filter may include an infrared filter or an infrared cut-off filter (IR cut-off). The optical filter may pass light of a set wavelength band and filter light of a different wavelength band. When the optical filter includes an infrared filter, it may block radiant heat emitted from external light from being transmitted to the image sensor (266). In addition, the optical filter may transmit visible light and reflect infrared light. The image sensor (266) may detect light that has sequentially passed through the lenses. The image sensor (266) may include a device capable of detecting incident light, such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor).

[0089]

[0090] Fig. 14 is a drawing showing another example of an optical system having a glass lens of the invention.

[0091] As shown in FIG. 14, the optical system may include a plurality of lenses aligned along the optical axis (OA) from the object toward the image sensor (281). The plurality of lenses may be five or more, for example, five to fifteen. The plurality of lenses may be first to tenth lenses (271-280).

[0092] The first lens (271) is closest to the object and may have a convex object-side surface and a concave sensor-side surface on the optical axis (OA). The first lens (271) may be provided with the glass material disclosed above. Since the first lens (271) is provided with a material having strong heat resistance, it is closest to the object and shrinkage or expansion of the lens due to the external environment can be suppressed. This prevents the optical axis of the lens from shifting and prevents a decrease in optical reliability. The object-side surface of the first lens (271) may have the largest effective diameter among the lenses. At least one of the object-side surface and the sensor-side surface of the first lens (271) may have a critical point.

[0093] The second lens (272) is positioned between the first lens (271) and the third lens (273), and may have a convex object-side surface and a concave sensor-side surface on the optical axis (OA).

[0094] The third lens (273) and the fourth lens (274) may be provided as cemented lenses. The object-side surface of the cemented lens may have a convex shape and the sensor-side surface may have a flat or concave shape. The object-side surface of the fifth lens (275) may be convex and the sensor-side surface may be flat, or concave or convex. The object-side surface of the sixth lens (276) may be convex, concave or flat, and the sensor-side surface may be flat, or concave or convex. The sixth lens (276) may have the smallest effective diameter among the lenses. The seventh lens (277) and the eighth lens (278) may be cemented together, and the object-side surface of the cemented lens may have a concave shape and the sensor-side surface may have a convex shape. The ninth lens (279) and the tenth lens (280) may be joined together, and the object-side surface of the joined lenses may have a convex shape and the sensor-side surface may have a convex shape. Except for the center spacing between the joined lenses, the center spacing between the eighth and ninth lenses (278, 279) among adjacent lenses may be the smallest.

[0095] An aperture (ST) may be arranged on the periphery between the sixth lens (276) and the seventh lens (277). The aperture (ST) may adjust the amount of light incident on the seventh lens (277). The optical system may include an optical filter (not shown) and / or a cover glass. The optical filter and the cover glass may be arranged between the last lens and the image sensor (281). The diagonal length of the image sensor (281) may be greater than the effective diameters of the fifth to eighth lenses (275-278).

[0096]

[0097] An optical system having these lenses can provide various camera modules, such as wide-angle, zoom, and small TTL, by increasing the degree of freedom in the shape of the glass lens. TTL is the optical axis distance from the center of the object-side surface of the first lens (261) to the image sensor (266). If this TTL is increased, the size of the camera module can be increased.

[0098]

[0099] An embodiment of the invention relates to a method for manufacturing a glass lens, comprising: mixing glass particles, a polymer, and an additive; injection-molding the mixture; degreasing the polymer; and sintering the glass material to form a lens. Furthermore, the glass lens material may be a mixture of polymer and glass particles, or glass particles with empty spaces where the polymer has been removed. Furthermore, the glass lens material may be a material in which the glass particles are connected or fixed to each other through heat treatment, ultraviolet treatment, or extrusion. Although these mixed and extruded materials contain glass particles, the polymer exists in the spaces between the particles, allowing for the use of manufacturing processes identical or similar to those for plastic materials. Furthermore, the extruded mixture is injection-molded into a lens shape through a mold assembly; heat treatment is used to degreasing the polymer; and the degreasing material is sintered near the glass transition temperature to remove the empty spaces, which are polymer regions, in the degreasing lens molded product. At this time, the glass particles transition to a slightly viscous state due to the high temperature energy, and combine with surrounding particles to fill the empty spaces. By removing voids between particles and increasing density through sintering, the material becomes glassy, ​​allowing the creation of lens-shaped glass. Furthermore, glass lenses can be manufactured with critical points on either the object-side or sensor-side surfaces.

[0100] The invention can increase productivity and reduce processing costs because the lens is manufactured without the need for high-temperature glass molding or glass polishing. Furthermore, because it utilizes injection molding, a common plastic lens processing technique, there are no restrictions on the shape of the processed lens. Furthermore, depending on the shape of the injection mold, the lens can have a critical point, spherical, aspherical, or freely shaped lens surface.

[0101]

[0102] The features, structures, effects, etc. described in the embodiments above are included in at least one embodiment of the present invention, and are not necessarily limited to just one embodiment. Furthermore, the features, structures, effects, etc. illustrated in each embodiment can be combined or modified and implemented in other embodiments by a person having ordinary skill in the art to which the embodiments pertain. Therefore, the contents related to such combinations and modifications should be interpreted as being included in the scope of the present invention. In addition, although the embodiments have been described above, these are merely examples and do not limit the present invention. Those having ordinary skill in the art to which the present invention pertains will appreciate that various modifications and applications not illustrated above are possible without departing from the essential characteristics of the embodiments. For example, each component specifically shown in the embodiments can be modified and implemented. In addition, the differences related to such modifications and applications should be interpreted as being included in the scope of the present invention defined in the appended claims.

Claims

1. A step of providing a mixture by mixing glass particles, a polymer filled between the glass particles, and an additive; A step of injection molding the above mixture by a mold assembly having a lens shape; A step of degreasing the polymer from a lens molded article injection-molded in the above lens shape; A step of sintering glass particles of a degreased molded article by the polymer; A step of processing the above sintered molded product to provide a glass lens, A method for manufacturing a glass lens, wherein at least one of the object-side surface and the sensor-side surface of the glass lens has a critical point.

2. In paragraph 1, A method for manufacturing a glass lens, wherein the temperature for injection molding the above-mentioned molded product is lower than the temperature for degreasing the polymer.

3. In paragraph 1, A method for manufacturing a glass lens, wherein the sintering temperature of the glass particles is higher than the temperature for debinding the polymer and the temperature for injection molding the molded product.

4. In any one of paragraphs 1 to 3, The above glass particles include silica particles, The above polymer is a method for manufacturing a glass lens including a thermoplastic plastic resin material.

5. In any one of paragraphs 1 to 3, Each of the above glass particles has a range of 10 nm to 500 nm, A method for manufacturing a glass lens, wherein the glass particles are mixed in an amount of 40 wt% to 60 wt% with respect to the mixed material.

6. In any one of paragraphs 1 to 3, A method for manufacturing a glass lens, wherein the mold assembly has multiple gates to inject the mixture into the inner cavity.

7. In any one of paragraphs 1 to 3, Glass particles; and a glass lens having a mixed material filled between the glass particles and having a refractive index different from that of the glass particles, The above glass lens has at least one critical point on the object side and the sensor side, The above glass lens is a glass lens having cut surfaces arranged on the outer sides symmetrically to each other.

8. A glass lens according to claim 7, wherein the number of cut surfaces is in the range of 2 to 4.

9. Includes a plurality of lenses aligned along the optical axis toward the image sensor from the object, At least one of the object-side lens and the last lens among the above plurality of lenses is a glass lens according to claim 7, An optical system having a glass lens, wherein the glass lens is positioned closest to the image sensor or closest to the object.

Images