Lens element

Abstract

The present invention relates to a lens element having both a color dividing function and a light collecting function, and provides a lens element having a novel configuration. The present invention pertains to a lens element having a substrate and a lens part, the lens part being provided with a plurality of microlenses disposed on the substrate so as to be separated from each other, the plurality of microlenses including two or more colors of microlenses having different spectral characteristics, the microlenses being formed from a photocurable resin composition, the surface not in contact with the substrate has a convex curved surface.

Description

Technical Field

[0001] The present invention relates to lens elements. Background Art

[0002] The solid-state imaging element applicable to the solid-state imaging device of a digital camera or a video camera has a plurality of photoelectric conversion elements that receive an optical image from an imaging object and convert the incident light into an electrical signal. As the photoelectric conversion element, known ones are: CCD (Charge Coupled Device) type, CDMOS (Complementary Metal Oxide Semiconductor) type, etc.

[0003] The solid-state imaging element can obtain the color information of the imaging object by using the color separation function of the color filter by providing a color filter that transmits light of a specific wavelength in the path of light incident to the photoelectric conversion element. In addition, it is known that in the solid-state imaging element, a micro lens is provided in order to efficiently guide light to the light receiving part of the photoelectric conversion element, and the micro lens focuses the light incident from the imaging object and guides it to the light receiving part of the photoelectric conversion element.

[0004] Conventionally, a color microlens having both the color separation function of the color filter and the light focusing function of the microlens is known. Patent Document 1 describes a solid-state imaging element having a color microlens obtained by coating a material including a photopolymerizable negative photosensitive resin and a pigment on a substrate and forming the color microlens into a lens shape by photolithography.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: International Publication No. 2019 / 220861 Summary of the invention

[0008] Problem that the invention aims to solve

[0009] The color microlens described in Patent Document 1 is configured such that the lens portions are in contact with each other, and further includes a light shielding film for suppressing color mixing between pixels and an inorganic film covering the lens portions.

[0010] An object of the present invention is to provide a lens element having a new structure and having both a color separation function and a light focusing function.

[0011] Solutions for solving problems

[0012] The present invention includes the following technical solutions.

[0013] [1] A lens element comprising a substrate and a lens portion,

[0014] The lens unit includes a plurality of micro lenses that are disposed separately from each other on the substrate.

[0015] The plurality of micro lenses include two or more micro lenses with different spectral characteristics.

[0016] The microlens is formed of a photocurable resin composition, and a surface not in contact with the substrate has a convex curved surface.

[0017] [2] The lens element according to [1], further comprising a cover layer,

[0018] The cover layer covers at least a portion of the curved surfaces of the plurality of microlenses.

[0019] [3] The lens element according to [2], wherein the cover layer fills a space between the microlenses that are arranged separately from each other.

[0020] [4] The lens element according to [3], wherein the cover layer covers all surfaces of the plurality of microlenses that are not in contact with the substrate, and the surface is flat.

[0021] [5] The lens element according to any one of [2] to [4], wherein the refractive index of the cover layer is lower than the refractive index of the microlens.

[0022] [6] The lens element according to any one of [2] to [5], wherein the refractive index of the cover layer is 1.1 or more.

[0023] [7] The lens element according to any one of [1] to [6], wherein the plurality of microlenses include green, blue, and red microlenses or include cyan, magenta, and yellow microlenses.

[0024] [8] The method for manufacturing a lens element according to any one of [2] to [7], comprising the following steps in order:

[0025] A step (a) of disposing the plurality of micro lenses on the substrate to form the lens portion;

[0026] A step (b1) of applying a cover layer-forming resin composition on the surface of the lens portion to form a coating film; and

[0027] A step (b2) of curing the coating film.

[0028] [9] The production method according to [8], wherein the step (a) comprises the following steps:

[0029] A step (a1) of coating the photocurable resin composition on the substrate to form a photocurable resin composition layer; and

[0030] step (a2) of selectively exposing the photocurable resin composition layer,

[0031] In the step (a2), the photocurable resin composition layer is exposed at an exposure amount that is 2.0 times or more of the saturated exposure amount.

[0032]

[10] A coating layer-forming resin composition used in the production method described in [8] or [9].

[0033]

[11] A solid-state imaging device comprising the lens element according to any one of [1] to [7].

[0034]

[12] A display device comprising the lens element according to any one of [1] to [7].

[0035] Effects of the Invention

[0036] The lens element according to the present invention has a lens portion including a plurality of micro lenses, presenting a structure in which the lens portion has both a color separation function and a light focusing function, and has a structure capable of suppressing color mixing between pixels. Therefore, it is possible to undertake multiple functions with a simple structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 is a cross-sectional view schematically showing a lens element according to the first embodiment.

[0038] Figure 2 This is a plan view showing a lens element according to the first embodiment.

[0039] Figure 3 is a cross-sectional view schematically showing the microlens according to the first embodiment.

[0040] Figure 4 is a cross-sectional view schematically showing a lens element according to the second embodiment.

[0041] Figure 5 It is a partial cross-sectional view showing each manufacturing step of the lens element according to the second embodiment.

[0042] Figure 6 This is a schematic diagram showing the propagation of light in a system in which a lens element is arranged on a solid-state imaging element and used.

[0043] Figure 7This is a schematic diagram showing the propagation of light in a system in which a lens assembly is arranged in a display device and used. DETAILED DESCRIPTION

[0044] The lens element of the present invention comprises a substrate and a lens portion, wherein the lens portion comprises a plurality of micro lenses separated from each other and arranged on the substrate, wherein the plurality of micro lenses include two or more micro lenses having different spectral characteristics, wherein the micro lenses are formed of a photocurable resin composition, and the surface not in contact with the substrate has a convex curved surface. Hereinafter, a mode for implementing the present invention will be described with reference to the accompanying drawings.

[0045] [Lens element]

[0046] <First Embodiment>

[0047] Figure 1 1 is a cross-sectional view schematically showing a lens element 1 according to the first embodiment. The lens element 1 has a substrate 10 and a lens portion 30. The lens portion 30 includes a plurality of micro lenses 31 arranged separately from each other on the substrate 10. The plurality of micro lenses 31 include two or more micro lenses having different spectral characteristics. The micro lenses 31 are formed of a photocurable resin composition, and the surface not in contact with the substrate 10 has a convex curved surface 31a.

[0048] The lens element 1 includes two or more micro lenses 31, and therefore has a function of a color filter, that is, a color separation function. In addition, the lens element 1 includes a plurality of micro lenses 31 having a convex curved surface 31a, and therefore has a focusing function of focusing light incident from the curved surface 31a. Furthermore, the lens element 1 presents a structure in which a plurality of micro lenses 31 are arranged separately from each other, and therefore has a function of suppressing color mixing. More specifically, in the lens portion 30, a plurality of micro lenses 31 are arranged separately from each other, and therefore, there is a gap (space between micro lenses) 30a between the micro lenses 31. Color mixing may occur when light passing through one micro lens 31 is incident on other micro lenses 31, but in the lens portion 30 of the present invention, light passing through one micro lens 31 needs to pass through the gap 30a between the micro lenses 31 before being incident on other micro lenses 31. That is, since the light passes through two boundaries (the boundary between the first microlens 31 and the gap 30a, and the boundary between the gap 30a and the second microlens 31), it is different from the structure described in Patent Document 1 which is arranged in contact with the microlens 31. Since the light passes through the gap 30a, it is possible to suppress the frequency of the light passing through the first microlens 31 from entering the other microlenses 31. Therefore, the lens element 1 has a function of suppressing color mixing. As described above, in the present invention, by presenting a structure in which the lens element 1 has multiple functions at the same time, it is possible to achieve multiple functions and thin film. In addition, it is possible to achieve multiple functions and simplify the structure.

[0049] The plurality of micro lenses 31 include micro lenses of two or more colors with different spectral characteristics. Examples of the plurality of micro lenses 31 include a configuration including three colors of green (G), blue (B), and red (R); a configuration including three colors of cyan (C), magenta (M), and yellow (Y); a configuration including four colors of cyan (C), magenta (M), yellow (Y), and green (G).

[0050] Figure 2 30. The top view shape of the microlens 31 can be adjusted according to the shape of the photomask used in the exposure step in the manufacturing method of the lens unit 30, and can be a rectangular shape such as a square or a rectangle (for example, Figure 2 ), round, oval.

[0051] Figure 3 A cross-sectional view of a microlens 31 in the lens portion 30 is shown. With respect to the microlens 31, in any cross-sectional view, the lens width W1 in contact with the substrate 10 is preferably 200 μm or less, more preferably 100 μm or less, and preferably 1 μm or more, more preferably 2 μm or more. The lens width W1 may be the same or different in all cross sections. When the microlens 31 is rectangular when viewed from above, the lens width W1 is a value that varies depending on the cross section. It is preferred that there is at least one cross section that satisfies the above-mentioned suitable numerical range of the lens width W1, and it is more preferred that it is satisfied in any cross section. The gap 30a ( Figure 1 ) can be appropriately designed according to the purpose of the lens element 1, but from the viewpoint of suppressing color mixing, in any cross-section, the cross-sectional length (width) of the gap 30a is preferably 0.1 times or more and 1 times or less, and more preferably 0.2 times or more and 0.8 times or less, relative to the cross-sectional length (width) of the microlens 31. The cross-sectional length (width) of the gap 30a is preferably 0.5 μm or more, and more preferably 1.0 μm or more. The cross-sectional length (width) of the gap 30a is, for example, 200 μm or less. The cross-sectional length (width) of the gap 30a may be the same or different in all cross-sections, and may be different in the same cross-section. For example, the cross-sectional length (width) may be different depending on the arrangement direction of the microlenses 31. Figure 2 , an example is shown in which the cross-sectional length (width) of the gap 30 a in the longitudinal arrangement of the microlenses 31 is longer than the cross-sectional length (width) of the gap 30 a in the lateral arrangement of the microlenses 31 .

[0052] Regarding the microlens 31, the ratio (W2 / W1) of the lens width W2 at a height H of 90% of the lens height from the substrate surface to the lens width W1 in contact with the substrate 10 is preferably 0.7 or less, more preferably 0.6 or less, and preferably 0.4 or more, more preferably 0.5 or more. By setting the ratio (W2 / W1) to the above range, the function as a microlens can be improved.

[0053] According to the manufacturing method described below, it is possible to obtain, by a simple method, a lens portion in which the lens width W1 and the ratio (W2 / W1) in each microlens are within the above range.

[0054] The lens element 1 of this embodiment can be used for the same purpose as the lens element with multiple micro lenses in the past. For example, it can be configured for use in a solid-state imaging element. In a solid-state imaging element, it can be used by being stacked on a photoelectric conversion element layer including multiple photoelectric conversion elements. Furthermore, by configuring the micro lenses in a manner corresponding to each photoelectric conversion element and configuring the photoelectric conversion element in a manner that incident light on the photoelectric conversion element with the aid of the micro lenses, it is possible to focus light of a desired color and make it incident on each photoelectric conversion element. There is no particular limitation on the specific form of the solid-state imaging element. For example, a plurality of photodiodes constituting the light receiving area of ​​the solid-state imaging element (CCD image sensor, CMOS image sensor or organic CMOS image sensor, etc.) and a plurality of photoelectric conversion elements made of polysilicon, etc. can be formed on a substrate, and the micro lenses can be configured in a manner corresponding to each photoelectric conversion element.

[0055] The lens element 1 of this embodiment can be configured in a display device for use, for example. In the display device, it can be used by stacking on a display element layer including a plurality of display elements, and further, by configuring micro lenses in a manner corresponding to each display element, and emitting light from the display element with the aid of the micro lenses, it is possible to achieve improved light utilization efficiency while generating a color image. The specific form of the display device is not particularly limited, and it can be used, for example, for a liquid crystal display device, an organic EL display device, etc., and can also be used for micro LEDs and micro OLEDs that magnify and project images for display.

[0056] <Second Embodiment>

[0057] Figure 4 2 is a cross-sectional view schematically showing a lens element 2 according to the second embodiment. The lens element 2 has a cover layer 40 in addition to the structure of the lens element 1 according to the first embodiment. The structure other than the cover layer 40 is the same as that of the lens element 1 according to the first embodiment, and thus the description thereof is omitted.

[0058] The cover layer 40 is a structure that covers at least a portion of the curved surface 31a of the plurality of micro lenses 31, and has a function of protecting the plurality of micro lenses 31 and the lens unit 30. In addition, the cover layer 40 is preferably a continuous layer that connects the plurality of micro lenses 31 to each other, and has a function of preventing the micro lenses 31 from peeling off from the substrate 10. In addition, as Figure 4 As shown in the figure, the cover layer 40 is preferably configured to fill the gaps 30a between the micro lenses 31 that are separated from each other and arranged on the substrate 10, and more preferably to cover the entire surface of the plurality of micro lenses 31 that is not in contact with the substrate 10. In this configuration, the contact area between the micro lenses 31 and the cover layer 40 can be increased, so it is easy to suppress the occurrence of peeling between the layers.

[0059] In this configuration, by appropriately adjusting the refractive index of the material forming the cover layer 40, the light incident efficiency in the curved surface 31a of the microlens 31 is improved and the light is prevented from leaking from the side of the microlens 31 to the cover layer 40. In addition, in this configuration, by appropriately adjusting the refractive index of the material forming the cover layer 40, for light incident on the microlens 31 from the lower surface opposite to the curved surface 31a in the microlens 31, the light is prevented from leaking from the side to the cover layer 40, and the light emission efficiency from the curved surface 31a can be improved. It should be noted that since the light can be prevented from leaking from the side of the microlens 31 to the cover layer 40, color mixing can be prevented.

[0060] The refractive index of the covering layer 40 is preferably lower than that of the microlens 31 (than any one of the multiple microlenses 31) and higher than that of air. By adjusting the refractive index in this way, light incident on the microlens 31 is easily totally reflected at the interface between the microlens 31 and the covering layer 40, which can improve the efficiency of light utilization. The refractive index of the covering layer 40 is preferably greater than 1.10, and more preferably greater than 1.20. The refractive index of the covering layer 40 is preferably less than 1.60, more preferably less than 1.49, and further preferably less than 1.45. It should be noted that in the present invention, the refractive index of the covering layer refers to the refractive index at a wavelength of 589 nm.

[0061] Figure 6 Schematically shows that the light leakage to the cover layer 40 can be suppressed in the mode in which the lens element 1 is arranged in a solid-state imaging element and used. In the mode in which the lens element 1 is arranged in a solid-state imaging element and used, light is incident from the curved surface 31a of the large lens 31. Even if there is a case in which light reaches the side surface 31b in the micro lens 31, the light is totally reflected at the interface between the micro lens 31 and the cover layer 40, thereby suppressing the light from leaking to the cover layer 40.

[0062] Figure 7Schematically shows that the light leakage to the cover layer 40 can be suppressed in the mode in which the lens element 1 is arranged in a display device and used. In the mode in which the lens element 1 is arranged in a display device and used, light is incident from the lower surface 31c of the microlens opposite to the curved surface 31a. Even if there is a case in which light reaches the side surface 31b in the microlens 31, the light is totally reflected at the interface between the microlens 31 and the cover layer 40, thereby suppressing the light from leaking to the cover layer 40.

[0063] The surface 40a of the cover layer 40 on the opposite side of the substrate 10 is preferably flat (small height difference). The higher the flatness, the lower the proportion of light reflected at the surface 40a of the cover layer 40, and the improvement of light utilization efficiency can be achieved. Regarding the degree of flatness, for example, when the distance from the surface of the substrate 10 to the surface 40a of the cover layer 40 is set to L, the minimum value of L is preferably more than 1 / 2 of the maximum value of L, and more preferably more than 2 / 3. In this specification, when the minimum value of L is more than 1 / 2 of the maximum value of L, the surface 40a of the cover layer 40 is considered to be flat. The surface roughness of the surface 40a of the cover layer 40 on the opposite side of the substrate 10 is preferably less than 20nm, and more preferably less than 10nm.

[0064] [Method for manufacturing lens element]

[0065] An example of a method for manufacturing the lens element 2 according to the second embodiment will be described. Figure 4The lens element 2 includes a lens portion 30 having three-color microlenses 31 (respectively referred to as "microlens 31A", "microlens 31B", and "microlens 31C"). A specific description is given of a manufacturing method for sequentially forming microlenses 31A, 31B, and 31C in the lens portion 30. The microlenses 31A, 31B, and 31C have different spectral characteristics and are formed by different photocurable resin compositions A, B, and C. The photocurable resin compositions A, B, and C can use, for example, resin compositions having the same composition except that only the type of colorant contained is different, and the types of colorant, resin, polymerizable compound, and photopolymerization initiator can all be different. The refractive index of the microlenses 31A, 31B, and 31C formed by the photocurable resin compositions A, B, and C is preferably greater than or equal to 1.50, and more preferably greater than or equal to 1.60. The refractive index of the microlenses 31A, 31B, and 31C is preferably less than or equal to 1.80. The refractive indexes of the microlenses 31A, 31B, and 31C may be the same or different. It should be noted that in the present invention, the refractive index of the microlens may refer to the refractive index at a wavelength where the transmittance in the visible light region of 380 nm to 780 nm reaches the maximum, and in order to be able to compare with the refractive index of the cover layer 40, it may also refer to the refractive index at a wavelength of 589 nm.

[0066] The lens element 2 sequentially includes: a step (a) of arranging a plurality of micro lenses 31A, 31B, and 31C on a substrate 10 to form a lens portion 30 ; and a step (b) of forming a cover layer 40 .

[0067] The lens element 1 of the first embodiment includes at least a step (a) of arranging a plurality of micro lenses 31A, 31B, and 31C on a substrate 10 to form a lens portion 30 .

[0068] <Lens Forming Step: Step (a)>

[0069] Step (a) includes a step of sequentially forming the microlens 31A, the microlens 31B, and the microlens 31C on the substrate 10. This step will be described.

[0070] First, if Figure 5 As shown in (a), the photocurable resin composition A is applied on the substrate 10 to form a photocurable resin composition layer 20A (photocurable resin composition layer forming step, step (a1)). The photocurable resin composition layer 20A is dried as needed. Figure 5 As shown in (b), the photocurable resin composition layer 20A is selectively exposed (exposure step, step (a2)). Figure 5In (b), the selectively exposed area in the photocurable resin composition layer 20A is shown as area 21A. The selective exposure of the photocurable resin composition layer 20A can be implemented by, for example, irradiating light through a photomask 50 or irradiating light using a spot. In the exposure process, the photocurable resin composition layer 20A is exposed to an exposure amount that is 2.0 times or more of the saturated exposure amount. Thereafter, the photocurable resin composition layer 21A is developed (development process). After the development process, there may be a post-baking process, and the post-baking process may be performed in succession to the development process. By going through the above-mentioned process, as Figure 5 As shown in (c) of FIG. 1 , a microlens 31A is formed on the substrate 10 .

[0071] Next, the microlens 31B is formed on the substrate 10. The microlens 31B can be formed by using a photocurable resin composition B on the substrate 10 on which the microlens 31A is formed, and performing a photocurable resin composition layer forming step, an exposure step, and a development step in sequence by the same method as the formation of the above-mentioned microlens 31A.

[0072] Next, a microlens 31C is formed on the substrate 10. The microlens 31C is formed by using a photocurable resin composition C on the substrate 10 on which the microlens 31A and the microlens 31B are formed, and the photocurable resin composition layer forming step, the exposure step, and the development step are sequentially performed in the same manner as the formation of the above-mentioned microlens 31A. The following will describe the various steps of forming the microlens 31A in more detail. The details of the various steps of forming the microlenses 31B and 31C are also the same.

[0073] <Photocurable resin composition layer forming step>

[0074] The photocurable resin composition is not limited as long as it has the property of being polymerized by light irradiation in the exposure step and having the unexposed portion being eluted by development in the development step. Specific examples of the photocurable resin composition will be described below.

[0075] As the substrate 10, a glass plate of quartz glass, borosilicate glass, alumina silicate glass, soda-lime glass coated with silicon dioxide on the surface, or the like; a resin plate of polycarbonate, polymethyl methacrylate, polyethylene terephthalate, or the like; a substrate of silicon, or a substrate having an aluminum, silver, or silver / copper / palladium alloy thin film formed on the above substrates, or the like can be used.

[0076] The coating method of the photocurable resin composition can be listed as extrusion coating, direct gravure coating, reverse gravure coating, CAP coating, die coating, etc. In addition, coating can be performed using a coating machine such as a dip coater, a rod coater, a spin coater, a slit & spin coater, a slit coater (sometimes also referred to as a die coater, a curtain coater, a non-spin coater), a roller, etc. Among them, it is preferred to use a spin coater for coating.

[0077] As a method for drying the photocurable resin composition layer 20A, natural drying, ventilation drying, reduced pressure drying, etc. can be listed. As a specific heating temperature, about 30 to 120°C can be listed, preferably about 60 to 100°C. As a heating time, it is suitable to be about 10 seconds to 60 minutes, preferably about 30 seconds to 30 minutes. Reduced pressure drying can be illustrated as being carried out under a pressure of about 50 to 150 Pa and in a temperature range of about 20 to 25°C. When the photocurable resin composition contains a solvent, the solvent can be removed by the above-mentioned drying.

[0078] The thickness of the photocurable resin composition layer 20A is not particularly limited and can be appropriately adjusted according to the material used, the purpose of the lens element, etc. For example, the thickness after drying can be exemplified as about 0.1 to 30 μm, preferably about 0.1 to 20 μm, more preferably about 0.3 to 10 μm, and further preferably about 0.5 to 10 μm.

[0079] <Exposure Process>

[0080] The selective exposure of the photocurable resin composition layer 20A can be carried out by, for example, exposing through a photomask 50. As the photomask 50, a mask having a light shielding portion formed corresponding to the part to be removed according to the target pattern is used. As the light source used in the exposure, it can be a light source having a wavelength exceeding 300nm, or it can be a light source having a wavelength below 300nm. For example, a filter that cuts off the wavelength range can be used to cut off the light less than 350nm, or a bandpass filter that takes out the wavelength range can be used to selectively take out the light near 436nm, near 408nm, and near 365nm. In addition, 248nm (KrF rays), 193nm (ArF rays) etc. can be used. As the light source, excimer lasers such as mercury lamps, light emitting diodes, metal halide lamps, halogen lamps, KrF excimer lasers, and ArF excimer lasers can be listed. It is preferable to use an exposure apparatus such as a mask aligner or a stepper because it is possible to uniformly irradiate the entire exposure surface with parallel light and accurately align the photomask 50 and the photocurable resin composition layer 20A.

[0081] Here, the photocurable resin composition layer 20A is exposed with an exposure amount of 2.0 times or more of the saturation exposure amount. The residual film rate of the photocurable resin composition layer 20A in the development process varies depending on the exposure amount in the exposure process. The residual film rate of the photocurable resin composition layer 20A increases as the exposure amount increases, and after the residual film rate reaches 100%, even if the exposure amount is increased, the residual film rate will be maintained at 100%. The residual film rate is calculated by the following formula (1).

[0082] Residual film rate (%) = (film thickness after development / film thickness before development) × 100 (1)

[0083] In this specification, the saturation exposure amount of the photocurable resin composition layer 20A is set as the minimum exposure amount at which the residual film rate becomes 95% or more and 100% or less (hereinafter also referred to as "absolute minimum exposure amount"). In actual measurement, the exposure amount is increased step by step, and the minimum exposure amount during measurement (hereinafter also referred to as "measurement minimum exposure amount") is measured. Specifically, when the exposure amount is increased step by step, after exposure with the exposure amount a, and then exposure with a larger exposure amount b, when the residual film rate first exceeds 95%, the measurement minimum exposure amount at which the residual film rate becomes 95% or more and 100% or less is measured as b, so it can be known that the absolute minimum exposure amount x is a value that satisfies a < x < b. By adjusting so that the exposure amount in the exposure process becomes 2 times or more of b, it is possible to achieve 2 times or more of x as the saturation exposure amount. That is, as long as the measurement minimum exposure amount b can be obtained, it is not necessarily necessary to determine the absolute minimum exposure amount x corresponding to the saturation exposure amount. The measurement minimum exposure amount b can be measured by, for example, the following method.

[0084] (Measurement of the measurement minimum exposure amount b)

[0085] For the photocurable resin composition layer with the same thickness obtained by coating the photocurable resin composition having the same composition as the photocurable resin composition layer 20A on the substrate by the same coating method and drying under the same conditions, using an exposure machine (TME-150RSK; manufactured by Topcon Corporation, light source; ultra-high pressure mercury lamp), in an atmospheric atmosphere, the exposure amount (based on 365 nm) is 1 mJ / cm 2 ~500 mJ / cm 2The light irradiation was performed in a range of 1, 10, 15, 20, 40, 60, 100, 150, 200, 300, 500, respectively. It should be noted that the light irradiation was performed by passing the radiated light from the ultra-high pressure mercury lamp through an optical filter (UV-31; manufactured by Asahi Techno Glass). The thickness of the photocurable resin composition layer after light irradiation was measured and set as the film thickness before development. The cured film was obtained by developing with the same developer and the same development conditions as the development process and post-baking. The thickness of the cured film was measured and set as the film thickness after development. The film thickness before development and the film thickness after development were measured using a contact film thickness measuring device (DEKT AK6M, manufactured by ULVAC).

[0086] In the above measurement, for example, the exposure amount is 60 mJ / cm 2 The residual film rate is 93% and the exposure dose is 100mJ / cm 2 When the residual film rate is 99%, the minimum exposure b for measuring the residual film rate to be 95% or more and 100% or less in actual measurement is 100 mJ / cm 2 .

[0087] Therefore, it can be known that when the minimum exposure b is measured to be 100 mJ / cm 2 In the case of 2 By exposing the photocurable resin composition layer 20A to the above exposure amount, it is possible to perform exposure at an exposure amount that is twice or more of the saturated exposure amount.

[0088] By adjusting the exposure amount of the photocurable resin composition layer 20A in the exposure process within a range exceeding the saturation exposure amount, the surface shape of each dot can be adjusted for the dot pattern obtained after the development process. When the exposure amount is set to 2.0 times or more of the saturation exposure amount, a dot having a convex surface that can function as a lens can be obtained.

[0089] The exposure amount of the photocurable resin composition layer 20A is not particularly limited as long as it is 2.0 times or more of the saturated exposure amount, and may be 2.1 times or more, 2.2 times or more, or 2.3 times or more of the saturated exposure amount, and is preferably 3.0 times or less of the saturated exposure amount.

[0090] <Development Process>

[0091] After the exposure process, a developing process is performed to develop the photocurable resin composition layer 20A. The photocurable resin composition layer 20A after exposure is contacted with a developer for development, so that the unexposed portion of the photocurable resin composition layer 20A is dissolved in the developer and removed, and a photocurable resin composition layer 20A with a pattern is formed on the substrate 10. As a developer, an aqueous solution of alkaline compounds such as potassium hydroxide, sodium bicarbonate, sodium carbonate, and tetramethylammonium hydroxide is preferably used. The concentration of these alkaline compounds in the aqueous solution is preferably 0.01 to 10% by mass, more preferably 0.03 to 5% by mass. Furthermore, the developer may contain a surfactant. The developing method may be any one of a paddle method, an immersion method, and a spray method. Furthermore, during development, the substrate 10 may be tilted to any angle. After development, it is preferably washed with water.

[0092] <Post-baking process>

[0093] After the development process, for example, a curing process can be performed by a post-exposure process using light with a wavelength of 254 to 350 nm, or a curing process can be performed by a post-baking process. It is preferred that the photocurable resin composition layer 20A is washed with water and a post-baking process is performed. From the viewpoint of being able to shorten the time required for manufacturing, the post-baking process is preferably performed in succession after the washing after the development process. By performing the post-baking process, the durability (solvent resistance) of the lens can be improved.

[0094] The post-baking process is a process for heating the photocurable resin composition layer 20A on the substrate. Heating is usually performed using a heating device such as an oven or a hot plate. The heating temperature is preferably 60 to 260° C. If the heating temperature is such a temperature, it is possible to prevent useless solvent from remaining in the film. The heating time is preferably 1 to 120 minutes, more preferably 10 to 60 minutes.

[0095] [Photocurable resin composition]

[0096] As described above, the photocurable resin composition used in the method for manufacturing the lens of the present invention is not limited as long as it has the property of being polymerized by light irradiation in the exposure process and the unexposed portion being dissolved by development in the development process, and has the desired spectral characteristics. Hereinafter, one form of the photocurable resin composition suitable for use in the present invention is described. The compounds exemplified as the components may be used alone or in combination of multiple types unless otherwise specified.

[0097] The photocurable resin composition of the present embodiment includes a resin (hereinafter referred to as resin (A)), a polymerizable compound (hereinafter referred to as polymerizable compound (C)), a photopolymerization initiator (hereinafter referred to as photopolymerization initiator (D)), a colorant, and a solvent (hereinafter referred to as solvent (E)). Furthermore, a polymerization initiator aid (hereinafter referred to as polymerization initiator aid (H)) may be included.

[0098] <Resin (A)>

[0099] Resin (A) is preferably an alkali-soluble resin, and more preferably a resin having a structural unit (Aa) (hereinafter referred to as "structural unit (Aa)") derived from at least one selected from the group consisting of unsaturated carboxylic acids and unsaturated carboxylic anhydrides. Resin (A) more preferably further comprises a structural unit (Ab) (hereinafter referred to as "structural unit (Ab)") having a carbazole ring. It should be noted that in this specification, "(meth)acrylic acid" means at least one compound selected from the group consisting of acrylic acid and methacrylic acid. Expressions such as "(meth)acryloyl" and "(meth)acrylate" also have the same meaning.

[0100] Specific examples of the monomer that realizes the structural unit (Aa) include:

[0101] Unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, o-vinylbenzoic acid, m-vinylbenzoic acid, and p-vinylbenzoic acid;

[0102] Unsaturated dicarboxylic acids such as maleic acid, fumaric acid, citraconic acid, mesaconic acid, itaconic acid, 3-vinylphthalic acid, 4-vinylphthalic acid, 3,4,5,6-tetrahydrophthalic acid, 1,2,3,6-tetrahydrophthalic acid, dimethyltetrahydrophthalic acid, 1,4-cyclohexenedicarboxylic acid, etc.;

[0103] Unsaturated dicarboxylic anhydrides such as maleic anhydride, citraconic anhydride, itaconic anhydride, vinylphthalic anhydride, tetrahydrophthalic anhydride, etc.;

[0104] Unsaturated acrylic acid esters containing a hydroxyl group and a carboxyl group in the same molecule, such as α-(hydroxymethyl)acrylic acid, etc.

[0105] Among these, acrylic acid, methacrylic acid, and the like are preferred from the viewpoint of copolymerization reactivity and solubility of the resulting resin in an aqueous alkali solution.

[0106] Specific examples of the monomer that realizes the structural unit (Ab) include unsaturated compounds having a carbazole ring. When the resin (A) contains the structural unit (Ab), the refractive index of the obtained film can be increased.

[0107] The unsaturated compound having a carbazole ring is preferably a compound represented by formula (III).

[0108]

[0109] [In formula (III), R 1 It represents a hydrogen atom, a methyl group or a hydroxymethyl group.

[0110] R 2 ~R 9 Each independently represents a hydrogen atom, a halogen atom, a saturated hydrocarbon group having 1 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms, and the hydrogen atom contained in the saturated hydrocarbon group may be substituted with an alkoxy group or an aryl group.

[0111] X represents a single bond, an alkanediyl group having 1 or more carbon atoms, or -CO(-OX 0 )m-(X 0 represents an alkanediyl group having 1 or more carbon atoms, and m represents an integer of 0 or more. ).

[0112] Examples of the compound represented by formula (III) include N-vinyl carbazole, N-allyl carbazole, N-(meth)acryloyl carbazole, 2-(9-carbazolyl)ethyl (meth)acrylate, 2-(9-carbazolyl)ethoxyethyl (meth)acrylate, 2-(9-carbazolyl)-2-methylethyl (meth)acrylate, and 2-(9-carbazolyl)-1-methylethyl (meth)acrylate.

[0113] The resin (A) may have a structural unit (Ac) different from the structural unit (Aa) and the structural unit (Ab).

[0114] Examples of the structural unit (Ac) include structural units derived from an unsaturated compound having a cyclic ether structure having 2 to 4 carbon atoms (e.g., at least one selected from the group consisting of an oxirane ring, an oxetane ring, and a tetrahydrofuran ring), structural units having an ethylenically unsaturated bond in a side chain, and other structural units.

[0115] Examples of the unsaturated compound having a cyclic ether structure having 2 to 4 carbon atoms (e.g., at least one selected from the group consisting of an oxirane ring, an oxetane ring, and a tetrahydrofuran ring) include, for example, glycidyl (meth)acrylate, β-methyl glycidyl (meth)acrylate, glycidyl vinyl ether, glycidyloxymethylstyrene; vinyl cyclohexene monoxide, 1,2-epoxy-4-vinylcyclohexane (e.g., CELLOXIDE 2000; manufactured by Daicel Corporation), 3,4-epoxycyclohexylmethyl (meth)acrylate (e.g., Cyclomer A400; manufactured by Daicel Corporation), 3,4-epoxycyclohexylmethyl (meth)acrylate (e.g., Cyclomer M100; manufactured by Daicel Corporation), 3,4-epoxytricyclo[5.2.1.0](meth)acrylate.2,6 ]decyl ester; 3-methyl-3-(meth)acryloyloxymethyloxetane, 3-ethyl-3-(meth)acryloyloxymethyloxetane; tetrahydrofurfuryl (meth)acrylate, etc.

[0116] The structural unit having an ethylenically unsaturated bond in the side chain can be produced by adding an unsaturated compound having a cyclic ether structure having 2 to 4 carbon atoms to a copolymer containing the structural unit (Aa), or by adding an unsaturated carboxylic acid to a copolymer containing a structural unit derived from an unsaturated compound having a cyclic ether structure having 2 to 4 carbon atoms. The latter resin may be further reacted with a carboxylic anhydride.

[0117] Examples of monomers that realize other structural units include:

[0118] Methyl (meth)acrylate, butyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-methylcyclohexyl (meth)acrylate, tricyclo[5.2.1.0 2,6 ] decane-8-yl ester, (meth) acrylic acid tricyclo[5.2.1.0 2,6 ]decen-8-yl ester, benzyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, N-phenylmaleimide, N-cyclohexylmaleimide, N-benzylmaleimide, styrene, vinyltoluene, etc.

[0119] The polystyrene-equivalent weight average molecular weight (Mw) of the resin (A) is preferably 3,000 to 100,000, more preferably 5,000 to 50,000, further preferably 5,000 to 20,000, and particularly preferably 5,000 to 10,000. When the weight average molecular weight (Mw) of the resin (A) is within the above range, the coating properties of the photocurable resin composition tend to be good.

[0120] The dispersion degree [weight average molecular weight (Mw) / number average molecular weight (Mn)] of the resin (A) is preferably 1.1 to 6.0, more preferably 1.2 to 4.0. When the dispersion degree is within the above range, the chemical resistance of the obtained film tends to be excellent.

[0121] The acid value of resin (A) is preferably 30 mg-KOH / g or more and 180 mg-KOH / g or less, more preferably 40 mg-KOH / g or more and 150 mg-KOH / g or less, and further preferably 50 mg-KOH / g or more and 135 mg-KOH / g or less. Here, the acid value is a value measured as the amount (mg) of potassium hydroxide required to neutralize 1 g of the resin, and can be obtained by titrating with a potassium hydroxide aqueous solution. If the acid value of resin (A) is within the above range, there is a tendency that the obtained film has excellent adhesion to the substrate.

[0122] The content of the resin (A) in the photocurable resin composition of the present invention is preferably 5% by mass or more and 70% by mass or less relative to the total amount of the solid content of the photocurable resin composition of the present invention, more preferably 10% by mass or more and 60% by mass or less, and further preferably 15% by mass or more and 55% by mass or less. If the content of the resin (A) is within the aforementioned range, there is a tendency that the obtained film has excellent heat resistance and excellent adhesion and chemical resistance to the substrate. Here, the solid content of the photocurable resin composition refers to: the amount obtained by removing the content of the solvent (E) from the total amount of the photocurable resin composition of the present invention.

[0123] <Polymerizable Compound (C)>

[0124] The polymerizable compound (C) is a monomer that reacts by the action of heat or a photopolymerization initiator (D), and examples of the monomer include compounds having an ethylenically unsaturated bond, and preferably include a (meth)acrylate compound.

[0125] The polymerizable compound is preferably a (meth)acrylic compound having three or more (meth)acryloyl groups, and more preferably trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, or dipentaerythritol hexa(meth)acrylate.

[0126] The weight average molecular weight of the polymerizable compound (C) is preferably 150 or more and 2,900 or less, and more preferably 250 or more and 1,500 or less.

[0127] The content of the polymerizable compound (C) in the photocurable resin composition of the present invention can be, for example, 1% by mass or more and 99% by mass or less, preferably 5% by mass or more and 90% by mass or less, more preferably 8% by mass or more and 80% by mass or less, and further preferably 10% by mass or more and 70% by mass or less relative to the total amount of the solid content of the photocurable resin composition. If the content of the polymerizable compound (C) is within the above range, the chemical resistance and mechanical strength of the obtained film can be improved.

[0128] <Photopolymerization Initiator (D)>

[0129] The photopolymerization initiator (D) is not particularly limited as long as it is a compound that can generate active free radicals, acids, etc. by the action of light and initiate the polymerization of the polymerizable compound (C), and a known photopolymerization initiator can be used. As the photopolymerization initiator (D), it is preferably a photopolymerization initiator comprising at least one selected from the group consisting of an O-acyl oxime compound, an alkyl phenone compound, a triazine compound, an acyl phosphine oxide compound, and a biimidazole compound, and more preferably a photopolymerization initiator comprising an O-acyl oxime compound. If it is these photopolymerization initiators, there is a tendency that the sensitivity is high and the transmittance in the visible light region becomes high.

[0130] Examples of such photopolymerization initiators include N-benzoyloxy-1-(4-phenylthiophenyl)butane-1-one-2-imine, N-benzoyloxy-1-(4-phenylthiophenyl)octane-1-one-2-imine, N-benzoyloxy-1-(4-phenylthiophenyl)-3-cyclopentylpropane-1-one-2-imine, 2-methyl-2-morpholino-1-(4-methylthiophenyl)propane-1-one, 2-dimethylamino-1-(4-morpholinophenyl)-2-benzylbutane-1-one, 1-hydroxycyclohexylphenyl ketone, 2,4-bis(trichloromethyl)-6-piperonyl-1,3,5-triazine, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, and 2,2′-bis(2-chlorophenyl)-4,4′,5,5′-tetraphenylbiimidazole.

[0131] The content of the photopolymerization initiator (D) in the photocurable resin composition of the present invention is preferably 0.1 parts by mass or more and 30 parts by mass or less, and more preferably 0.3 parts by mass or more and 20 parts by mass or less, relative to 100 parts by mass of the total amount of the resin (A) and the polymerizable compound (C). If the content of the photopolymerization initiator (D) is within the above range, the transmittance of the visible light transmission part of the obtained pattern tends to be high.

[0132] <Polymerization initiator aid (H)>

[0133] The polymerization initiator aid (H) is a compound or sensitizer used together with the photopolymerization initiator (D) to promote the polymerization of the polymerizable compound (C) which has been polymerized by the photopolymerization initiator (D). When the polymerization initiator aid (H) is included, it is usually used in combination with the photopolymerization initiator (D).

[0134] Examples of the polymerization initiator aid (H) include 4,4′-bis(dimethylamino)benzophenone (commonly known as Michler's ketone), 4,4′-bis(diethylamino)benzophenone, 9,10-dimethoxyanthracene, 2,4-diethylthioxanthone, and N-phenylglycine.

[0135] When the photocurable resin composition of the present invention contains a polymerization initiator aid (H), the content thereof is preferably 0.1 parts by mass or more and 30 parts by mass or less, and more preferably 0.2 parts by mass or more and 10 parts by mass or less, relative to 100 parts by mass of the total content of the resin (A) and the polymerizable compound (C). When the amount of the polymerization initiator aid (H) is within the above range, there is a tendency for the sensitivity to become higher when forming a pattern.

[0136] <Colorant>

[0137] The colorant includes at least one selected from the group consisting of dyes and pigments. The colorant preferably includes a combination of two dyes or a combination of at least one dye and at least one pigment, and more preferably includes a combination of two dyes or a combination of one dye and one pigment.

[0138] As dyes, known dyes can be used, and solvent dyes, acid dyes, direct dyes, mordant dyes, etc. can be listed. For example, compounds classified as solvents, acids, alkalis, reactive dyes, direct dyes, disperse dyes, mordant dyes or vat dyes in the Dye Index (published by The Society of Dyers and Colourists) can be listed; known dyes recorded in the Dyeing Notes (Color Dyeing Company). The dye can be appropriately selected according to the desired spectral characteristics of the microlens array. These dyes can be used alone or in combination of two or more. The dye is preferably an organic solvent-soluble dye. As pigments, organic pigments and inorganic pigments can be listed, and compounds classified as pigments in the Dye Index (published by The Society of Dyers and Colourists) can be listed.

[0139] <Solvent (E)>

[0140] The photocurable resin composition of the present invention contains a solvent (E). The solvent (E) is not particularly limited, and examples thereof include solvents commonly used in the art. Examples thereof include ester solvents (solvents containing -COO- but not containing -O- in the molecule), ether solvents (solvents containing -O- but not containing -COO- in the molecule), ether ester solvents (solvents containing -COO- and -O- in the molecule), ketone solvents (solvents containing -CO- but not containing -COO- in the molecule), alcohol solvents (solvents containing OH but not containing -O-, -CO- and -COO- in the molecule), aromatic hydrocarbon solvents, amide solvents, dimethyl sulfoxide, and the like.

[0141] Examples of the solvent include methyl lactate, ethyl lactate, butyl lactate, methyl 2-hydroxyisobutyrate, ethyl acetate, n-butyl acetate, isobutyl acetate, amyl formate, isoamyl acetate, butyl propionate, isopropyl butyrate, ethyl butyrate, butyl butyrate, methyl pyruvate, ethyl pyruvate, propyl pyruvate, methyl acetoacetate, ethyl acetoacetate, cyclohexanol acetate, and an ester solvent of γ-butyrolactone;

[0142] Ether solvents such as ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, 3-methoxy-3-methylbutanol diethylene glycol dimethyl ether, and diethylene glycol ethyl methyl ether; ether ester solvents such as ethyl 3-methoxypropionate, methyl 3-ethoxypropionate, 3-methoxybutyl acetate, propylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, and diethylene glycol monoethyl ether acetate; ketone solvents such as 4-hydroxy-4-methyl-2-pentanone, heptanone, 4-methyl-2-pentanone, cyclopentanone, and cyclohexanone; alcohol solvents such as butanol, hexanol, and propylene glycol; amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone, etc.

[0143] As the solvent, propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, ethyl lactate, ethyl 3-ethoxypropionate, and 4-hydroxy-4-methyl-2-pentanone are more preferred.

[0144] As the solvent, propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, ethyl 3-ethoxypropionate, ethyl lactate, ethylene glycol ethyl methyl ether, cyclohexanone, methoxybutanol, and methoxybutyl acetate are preferred, and propylene glycol monomethyl ether acetate is more preferred.

[0145] The content of the solvent (E) in the photocurable resin composition of the present invention is generally 99.99% by mass or less relative to the total amount of the photocurable resin composition, preferably 40% by mass or more and 99% by mass or less, more preferably 50% by mass or more and 97% by mass or less, further preferably 60% by mass or more and 95% by mass or less, and further preferably 65% ​​by mass or more and 90% by mass or less. In other words, the total amount of the solid content of the photocurable resin composition of the present invention is generally 0.01% by mass or more, preferably 1% by mass or more and 60% by mass or less, more preferably 3% by mass or more and 50% by mass or less, further preferably 5% by mass or more and 40% by mass or less, and further preferably 10% by mass or more and 35% by mass or less. If the content of the solvent (E) is within the above range, the flatness during coating becomes good, and in addition, when forming a color filter, the color concentration will not be insufficient, so there is a tendency for the display characteristics to become good.

[0146] <Other ingredients>

[0147] The photocurable resin composition of the present invention may contain additives known in the art such as a filler, other polymer compounds, a leveling agent, an antioxidant, a curing agent, an ultraviolet absorber, a chain transfer agent, and an adhesion promoter, as required.

[0148] <Method for producing photocurable resin composition>

[0149] The photocurable resin composition of the present embodiment can be prepared by mixing the resin (A), the polymerizable compound (C), the photopolymerization initiator (D), the colorant and the solvent (E), and other components such as the polymerization initiator aid (H) by a known method. After mixing, it is preferably filtered using a filter with a pore size of about 0.05 to 1.0 μm.

[0150] <Coating Layer Forming Resin Composition>

[0151] The covering layer 40 is formed of a covering layer-forming resin composition. The covering layer-forming resin composition includes a resin, a polymerizable compound, a photopolymerization initiator, and the like. The refractive index of the covering layer-forming resin composition can be lower than that of the photocurable resin composition, and the same resin, polymerizable compound, and photopolymerization initiator as those described in the photocurable resin composition can be used. The resin in the covering layer-forming resin composition preferably has the aforementioned structural unit (Aa) and structural unit (Ac).

[0152] As a method of laminating the cover layer forming resin composition on the substrate 10 , the cover layer forming resin composition may be applied on the surface of the lens portion 30 so as to completely cover the exposed surface of each microlens 31 , and then irradiated with active energy rays to cure.

[0153] The coating can be carried out by common methods such as micro gravure coating, roll coating, dip coating, spin coating, die coating, cast transfer, flow coating, spray coating, etc. From the viewpoint of easily improving the optical properties of the cover layer, it is preferred to laminate the cover layer forming composition by micro gravure coating or die coating.

[0154] Thereafter, by irradiating active energy rays, the composition for forming a covering layer is cured to obtain the target covering layer. As active energy rays, for example, electron beams, ultraviolet rays, visible rays, etc. can be listed, which are appropriately selected according to the type of the covering layer forming composition used. The intensity of the irradiated active energy rays, the irradiation time, etc. are appropriately selected according to the type of the covering layer forming composition used, the thickness of the covering layer, etc. The active energy rays can be irradiated in an inert gas atmosphere. In order to irradiate active energy rays in a nitrogen atmosphere, for example, as long as the active energy rays are irradiated in a container sealed with an inert gas, nitrogen, argon, etc. can be used as the inert gas.

[0155] Description of Reference Numerals

[0156] 1, 2 lens element, 10 substrate, 20 photocurable resin composition layer, 30 lens portion, 40 cover layer, 50 photomask.

Claims

1. A lens element comprising a substrate and a lens portion, The lens unit includes a plurality of micro lenses that are arranged separately from each other on the substrate. The plurality of micro lenses include two or more micro lenses with different spectral characteristics. The microlens is formed of a photocurable resin composition, and a surface not in contact with the substrate has a convex curved surface.

2. The lens element according to claim 1, further comprising a cover layer, The covering layer covers at least a portion of the curved surfaces of the plurality of micro lenses.

3. The lens element according to claim 2, wherein: The cover layer fills in spaces between the micro lenses that are arranged to be separated from each other.

4. The lens element according to claim 3, wherein: The covering layer covers all surfaces of the plurality of micro lenses that are not in contact with the substrate, and has a flat surface.

5. The lens element according to claim 4, wherein: The cover layer has a refractive index lower than that of the microlens.

6. The lens element according to claim 5, wherein: The refractive index of the cover layer is greater than 1.

1.

7. The lens element according to claim 1 or 2, wherein: The plurality of micro lenses include green, blue, and red micro lenses or include cyan, magenta, and yellow micro lenses.

8. The method for manufacturing a lens element according to claim 2 or 3, comprising the following steps in sequence: (a) disposing the plurality of micro lenses on the substrate to form the lens portion; a step (b1) of applying a cover layer-forming resin composition on the surface of the lens portion to form a coating film; and A step (b2) of curing the coating film.

9. The manufacturing method according to claim 8, wherein: The step (a) comprises the following steps: A step (a1) of coating the photocurable resin composition on the substrate to form a photocurable resin composition layer; and step (a2) of selectively exposing the photocurable resin composition layer, In the step (a2), the photocurable resin composition layer is exposed at an exposure amount that is 2.0 times or more of a saturated exposure amount. 10 . A coating layer-forming resin composition, which is used in the production method according to claim 8 . 11 . A solid-state imaging element comprising the lens element according to claim 1 . 12 . A display device comprising the lens element according to claim 1 .

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