Lens, optical device, imaging device, electronic device, method of manufacturing lens, and mold

Abstract

The present application relates to a lens, an optical apparatus, an imaging apparatus, an electronic apparatus, a method of manufacturing a lens, and a mold. A lens including a resin is provided, wherein the lens includes a lens surface having a shape including a curved surface on a central portion of the lens and including a cusp on an outer side of the central portion, and wherein the lens surface is rougher at a position of the cusp than the curved surface on the central portion.

Description

Technical Field

[0001] This disclosure relates to lenses, optical devices, imaging devices, electronic devices, methods for manufacturing lenses, and molds. Background Technology

[0002] In recent years, smartphone optical systems have trended towards larger sensor sizes, and the number of lenses has been continuously increasing to suppress aberrations. When the number of lenses increases while the lens thickness remains the same as that of lenses in existing technologies, the amount of lens unit protruding from the smartphone body becomes larger.

[0003] On the other hand, as lenses become even thinner in the future, it is expected that manufacturing lenses using conventional injection molding will become difficult. Therefore, manufacturing methods other than injection molding are needed.

[0004] Japanese Patent Application Publication No. 2005-511367 discloses the preparation of a preform of thermoplastic resin, which is then pressed to form a lens.

[0005] International publication WO00 / 012291 discloses a method for manufacturing lenses by pressing thermoplastic resin sheets together. Summary of the Invention

[0006] This disclosure relates to providing lenses with high precision that are free of any appearance defects.

[0007] To address the aforementioned problems, a lens comprising resin is provided, wherein the lens includes a lens surface having a shape comprising a curved surface on a central portion of the lens and an inflection point on an outer side of the central portion, and wherein the lens surface is rougher at the location of the inflection point than the curved surface on the central portion. Furthermore, an optical device is provided, comprising: an optical system including the aforementioned lens; and a housing configured to encapsulate the optical system. Furthermore, a camera device is provided, comprising: an optical system including the aforementioned lens; and an imaging element configured to receive light that has passed through the optical system. Furthermore, an electronic device is provided, comprising: an optical system including the aforementioned lens; an imaging element configured to receive light that has passed through the optical system; and a display element configured to display an image captured by the imaging element. Furthermore, an electronic device is provided, comprising: an optical system including the aforementioned lens; an imaging element configured to receive light that has passed through the optical system; and a light-emitting element configured to illuminate a photographic object.

[0008] Furthermore, a method for manufacturing a lens is provided, the method comprising: preparing a sheet containing resin; and shaping the sheet into a lens shape by pressing it with a mold, wherein, during the shaping process, after pressing a first portion of the sheet corresponding to a central portion of the lens with the mold, a second portion of the sheet corresponding to an outer portion of the central portion is pressed with the mold. Additionally, a mold for pressing a resin-containing sheet to shape the sheet into a lens shape is provided, the mold comprising: a portion for pressing a first portion of the sheet, the first portion of the sheet corresponding to a central portion of the lens; and a portion for pressing a second portion of the sheet, the second portion of the sheet corresponding to an outer portion of the central portion, wherein the portion for pressing the first portion of the sheet is shaped to protrude beyond the portion for pressing the second portion of the sheet.

[0009] The features of this disclosure will become apparent from the following description of embodiments with reference to the accompanying drawings. The following description of the embodiments is given by way of example. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of sheet forming using existing technology.

[0011] Figure 2 This is a schematic diagram illustrating an example of a lens according to this disclosure.

[0012] Figure 3A This is a schematic diagram illustrating the state of the sheet forming process prior to the start of forming in the first embodiment of this disclosure.

[0013] Figure 3B This is a schematic diagram illustrating the initial portion of sheet forming in a first embodiment of the present disclosure.

[0014] Figure 3C This is a schematic diagram illustrating the intermediate portion of sheet forming in the first embodiment of this disclosure.

[0015] Figure 3D This is a schematic diagram illustrating the final part of sheet forming in the first embodiment of this disclosure.

[0016] Figure 4A This is a schematic diagram illustrating the state of the sheet forming process prior to the start of forming in the first embodiment of this disclosure.

[0017] Figure 4B This is a schematic diagram illustrating the initial separation of the sheet forming process in the first embodiment of this disclosure.

[0018] Figure 4CThis is a schematic diagram illustrating the final separation of the sheet forming process in the first embodiment of this disclosure.

[0019] Figure 5A This is a schematic diagram illustrating the state of the sheet forming process before the start of forming in the second embodiment of this disclosure.

[0020] Figure 5B This is a schematic diagram illustrating the intermediate portion of sheet forming in a second embodiment of the present disclosure.

[0021] Figure 5C This is a schematic diagram illustrating the final part of sheet forming in a second embodiment of this disclosure. Detailed Implementation

[0022] In the following description, embodiments for carrying out this disclosure are illustrated with reference to the accompanying drawings. However, the embodiments described below are merely exemplary embodiments of this disclosure, and the disclosure is not limited thereto. Common configurations are described with reference to several accompanying drawings, and descriptions of configurations indicated by the same reference numerals are appropriately omitted. Different items with the same name can be distinguished from each other by adding ordinal numbers to the item names (e.g., "first item", "second item", etc.).

[0023] When manufacturing lenses with concave surfaces having large aperture angles and large thickness variations by pressing sheets (e.g., lenses found in smartphone optics systems), wrinkled appearance defects may occur because the elongation of the sheet is suppressed at its central portion.

[0024] In the configurations disclosed in Japanese Patent Application Publication No. 2005-511367 and International Publication No. WO00 / 012291, thin lenses can be manufactured by press forming. However, for lenses (especially lenses with concave surfaces having large aperture angles and large thickness variations), the formation of wrinkles cannot be suppressed.

[0025] refer to Figure 1 A method for manufacturing lenses using sheet forming based on prior art is described. A sheet 11 of thermoplastic resin is placed between a heated upper mold 12 and a lower mold 13. The upper mold 12 is driven, causing the sheet 11 to be clamped between the upper mold 12 and the lower mold 13. The sheet 11 is plastically deformed by pressing under heat. After cooling, the sheet 11 is released from the mold. The mold is heated, for example, with a heater, and cooled by passing cooling water through the mold after the heater is turned off. This method allows for the formation of a desired lens shape according to the mold. However, elongation occurs in the portions of the sheet 11 that interfere with the mold, resulting in wrinkles forming in the sheet 11 at the locations where the elongated portions contact. This disclosure relates to suppressing the formation of wrinkles to provide lenses without any appearance defects. <Example>

[0026] The lens according to this disclosure is a resin-containing lens. The lens has the following characteristics: The lens includes a lens surface having a shape that includes a curved surface on the central portion of the lens and an inflection point on the outer side of the central portion. The lens surface is rougher at the location of the inflection point than the curved surface on the central portion. Figure 2 This is a cross-sectional view illustrating an example of a lens according to the present disclosure. The central portion 21 has a curved surface (concave surface), and an inflection point 22 is located on the outer side of the central portion 21. In the embodiments described herein, an inflection point is defined as the point where the sign of the curvature of the lens surface changes (including points where the sign changes from positive to negative, from positive to 0, and from negative to 0). In the embodiments described herein, the central portion of the lens serves as the optical portion (optically effective area). However, the central portion and the optical portion do not always need to be perfectly aligned with each other, and only need to be aligned with each other to the extent that the effects of the present disclosure are achieved.

[0027] The method for manufacturing a lens according to this disclosure includes: preparing a sheet containing resin; and shaping the sheet into a lens shape by pressing the sheet with a mold. During the shaping process, after pressing a first portion of the sheet corresponding to the central portion of the lens with a mold, a second portion of the sheet corresponding to the outer side of the central portion is pressed with a mold.

[0028] refer to Figures 3A to 3D The pressing and forming of the lens in the first embodiment is described. First, as preparation, a sheet containing resin is prepared. Figures 3A to 3D This is a schematic diagram illustrating a sheet 31 of thermoplastic resin placed between the upper mold 32 and the lower mold 33. As a material for the sheet 31, for example, a cycloolefin resin can be used. Besides thermoplastic resins, the sheet 31 can be made of any material, such as thermosetting resins, that can be deformed by pressing with a mold and has the desired optical properties.

[0029] The mold for pressing the sheet 31 includes: a first portion 31-1 for pressing the sheet 31 corresponding to the center portion of the lens; and a second portion 31-2 for pressing the sheet 31 corresponding to the outer side of the center portion of the lens. The mold can be configured such that the first portion 31-1 of the sheet 31 protrudes beyond the second portion 31-2 of the sheet 31. Furthermore, the first portion 31-1 of the sheet 31 can be configured such that its protrusion decreases as pressing proceeds. Additionally, the first portion of the sheet 31 can be held in place by an elastic medium. The use of the mold as described above allows for efficient forming without separating the first and second portions. In this embodiment, the insert 34 for forming the center portion of the lens is connected to the upper mold 32 by a spring therebetween. The upper mold 32 and the lower mold 33 are heated, for example, by a heater.

[0030] Before the forming process begins, such as Figure 3A As shown, the spring is in the extended state. Therefore, during the forming process, as... Figure 3B As shown, the insert 34 first contacts the sheet 31 as the upper mold 32 moves downward. Then, as... Figure 3C As shown, as the spring gradually compresses, the upper mold 32 gradually moves downward. As a result, the upper mold 32 comes into contact with the second portion of the sheet 31, which corresponds to the area on the outer side of the first portion. Finally, as... Figure 3D As shown, when the insert 34 contacts the upper mold 32, the movement of the insert 34 caused by the spring stops. As a result, the desired lens shape is obtained. After forming, cooling water is passed through the mold to release the sheet from the mold.

[0031] In existing press forming techniques, when the elongation of the first portion of the sheet corresponding to the optical portion is suppressed by the elongation of the second portion of the sheet corresponding to the non-optical portion located outside the optical portion, there is a risk of wrinkling in the first portion of the sheet. In this embodiment, the insert 34 first presses the sheet 31, so the elongation of the first portion 31-1 of the sheet 31 is not suppressed. Even when the elongation occurs in the second portion 31-2 outside the first portion 31-1 and interferes with the elongation that has already occurred, wrinkles are formed in the second portion 31-2. That is, forming can be performed while the wrinkles formed in the first portion 31-1 are extending toward the second portion. In this way, a lens with a lens surface that is rougher at the inflection point than at the center portion can be obtained.

[0032] This method is particularly advantageous, for example, when shaping a form with a concave central portion as a curved surface. For instance, it can shape a lens corresponding to a lens having a central portion with a concave surface and a thickness of 0.3 mm or less at the central portion. Furthermore, the method is particularly advantageous when the lens to be formed includes a central portion with a convex surface, in shaping, for example, a sheet with a convex surface into a lens shape with a smoother (smaller curvature) convex surface.

[0033] The size of the lens is not limited to any particular size. The use of this disclosure enables the precise forming of small-sized lenses. The lens size can be set to a diameter, for example, greater than 10 mm and less than 20 mm. As for the lens shape, the thickness at the central portion of the lens can be set to be less than the thickness at a location on the outer side of the central portion (e.g., at the inflection point). Furthermore, as for the thickness, the thickness at the central portion of the lens can be set to 0.3 mm or less.

[0034] Furthermore, the method may also include separating the sheet into individual lenses after forming. For example... Figure 4A As shown, multiple inserts 34 are provided, and the upper mold 32 and lower mold 33 are each formed as an integral structure, thereby forming a large number of lenses in one step. After the upper mold 32 moves upward and the sheet 31 is released from the mold, as... Figure 4B As shown, a stamping die 35 with a structure for cutting sheet 31 is arranged opposite to the lower die 33 instead of the upper die 32, and as... Figure 4C The sheet is moved downwards as shown, thereby separating it into individual lenses, each with a lens shape. Cutting marks can be retained after separation, and thus the lenses can have a protruding shape at their outer peripheral ends throughout the circumference.

[0035] Next, refer to Figures 5A to 5C The pressing and forming of the lens in the second embodiment is described. For example... Figure 5A As shown, in this embodiment, the sheet 41 has a greater thickness at the first portion 41-1 corresponding to the optical portion (center portion) than at the portion on its outer side (second portion 41-2). In... Figure 5B After the sheet 41 is sandwiched between the upper die 42 and the lower die 43, the upper die 42 gradually moves downward. Then, the upper die 42 first presses down on the first portion 41-1 of the sheet 41. The upper die 42 then moves further downward, thus... Figure 5C The desired lens shape is formed as shown. In this embodiment, a first portion of the sheet is first pressed with a mold to form the central portion (optical portion) of the lens. Consequently, the sheet is elongated to the second portion. As a result, as in the first embodiment, wrinkles are prevented from forming in the central portion of the lens.

[0036] The other configurations and effects are the same as those in the first embodiment.

[0037] Optical devices can be configured by encapsulating an optical system including a lens according to the present disclosure in a housing. Furthermore, imaging devices can be configured by combining an optical system including a lens according to the present disclosure with an imaging element configured to receive light that has passed through the optical system. Additionally, electronic devices such as smartphones can be configured by combining an optical system including a lens according to the present disclosure, an imaging element configured to receive light that has passed through the optical system, and a display element configured to display an image captured by the imaging element. Furthermore, electronic devices such as endoscopes can be configured by combining an optical system including a lens according to the present disclosure, an imaging element configured to receive light that has passed through the optical system, and a light-emitting element configured to illuminate a photographic object.

[0038] This disclosure is not limited to the above embodiments, and many modifications can be made within the technical concept of this disclosure. Furthermore, the effects described in the embodiments are merely examples of the most suitable effects produced by this disclosure, and the effects of this disclosure are not limited to those described in the embodiments.

[0039] The embodiments described above can be appropriately modified without departing from the technical concept. For example, multiple embodiments can be combined. Furthermore, at least one part of an embodiment can be deleted or replaced.

[0040] Furthermore, new items may be added to at least one embodiment. The disclosure in this specification includes not only what is explicitly described herein, but also all matters that can be understood from this specification and the accompanying drawings.

[0041] According to this disclosure, lenses without any appearance defects can be provided with high precision.

[0042] While this disclosure has been described with reference to embodiments, it should be understood that this disclosure is not limited to the disclosed embodiments. The scope of the appended claims should be given the broadest interpretation to cover all such modifications and equivalent structures and functions.

Claims

1. A lens comprising resin, wherein The lens includes a lens surface having a shape that includes a curved surface on the central portion of the lens and an inflection point on the outer side of the central portion. The lens surface is rougher at the inflection point than the curved surface at the center portion.

2. The lens of claim 1, wherein, The curved surface on the central portion is a concave surface.

3. The lens according to claim 1, wherein, The lens has a protruding shape at its outer peripheral end that extends across the entire circumference.

4. The lens according to claim 1, wherein, The resin is a thermoplastic resin.

5. The lens according to claim 1, wherein, The thickness of the lens at the central portion is less than the thickness of the lens at the inflection point.

6. The lens according to claim 1, wherein, The thickness of the lens at the central portion is 0.3 mm or less.

7. The lens according to claim 1, wherein, The resin is a cyclic olefin resin.

8. An optical device, comprising: An optical system comprising a lens according to any one of claims 1 to 7; as well as A housing configured to encapsulate the optical system.

9. A camera device, comprising: An optical system comprising a lens according to any one of claims 1 to 7; as well as A camera element is configured to receive light that has passed through the optical system.

10. An electronic device comprising: An optical system comprising a lens according to any one of claims 1 to 7; A camera element configured to receive light that has passed through the optical system; as well as A display element is configured to display an image captured by the camera element.

11. An electronic device comprising: An optical system comprising a lens according to any one of claims 1 to 7; A camera element configured to receive light that has passed through the optical system; as well as A light-emitting element, configured to illuminate the object being photographed.

12. A method of manufacturing a lens, the method comprising: Prepare sheets containing resin; as well as The sheet is shaped into a lens shape by pressing it with a mold. During the forming process, after pressing the first portion of the sheet corresponding to the center portion of the lens with the mold, the second portion of the sheet corresponding to the outer side of the center portion is pressed with the mold.

13. The method of manufacturing a lens according to claim 12, wherein, The forming process is performed while the sheet is being heated.

14. The method of manufacturing a lens according to claim 12, wherein, During the forming process, the sheet is shaped such that the thickness of the lens at the central portion is less than the thickness of the lens at the position on the outer side of the central portion.

15. The method of manufacturing a lens according to claim 12, wherein, During the forming process, the lens shape corresponds to a lens having a central portion with a concave surface and a thickness of 0.3 mm or less at the central portion.

16. The method of manufacturing a lens according to claim 12, further comprising separating the sheet into pieces each having the lens shape after the forming process.

17. A mold for pressing a resin-containing sheet to form the sheet into a lens shape, the mold comprising: The portion used to press the first part of the sheet, the first part of the sheet corresponding to the central portion of the lens; as well as The portion used to press the second part of the sheet, the second part of the sheet corresponding to the outer side of the central portion, The portion of the first part used to press the sheet is shaped to protrude beyond the portion used to press the second part of the sheet.

18. The mold according to claim 17, wherein, The portion used to press the first part of the sheet is shaped such that the protrusion decreases as the pressing proceeds.

19. The mold according to claim 18, wherein, The portion of the first part used to press the sheet is held in place by an elastomer.

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