Light absorber and method for manufacturing the same

Abstract

To provide an optical absorber having high optical absorbency without generating scattered light, and a method for manufacturing the same.SOLUTION: An optical absorber being a projection film 11 formed to project on the surface of a substrate 10 and consisting of a black matrix formation resist has a thickness t of 500 μm or less and preferably, 100 μm or less from the surface of the substrate and an optical density (an OD value) in a range of 350-1350 nm of 3.0 or more. A method for manufacturing the optical absorber comprises: exposing the surface of the substrate 10 to which the black matrix formation resist is applied; and forming a sunspot-shaped projection film having the thickness of 500 μm or less from the surface of the substrate 10 and the optical density (the OD value) of 3.0 or more in the range of 350-1350 nm. The optical absorber is used for the optical elements of medical equipment and spectacle equipment.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a light absorber used for optical elements of medical devices and spectacle devices, and a method for manufacturing the same.

Background Art

[0002] In an apparatus that obtains information using light, a light absorber may be required for adjusting the amount of light and the optical path, and removing reflected light that causes ghosting and flare. This film is produced by physical and chemical methods such as vapor deposition and coating on glass or plastic materials. Particularly in applications related to medical and spectacle devices, an optical element is formed that absorbs and removes harmful reflected light and scattered light that occurs in the cornea and lens of the eye, and is referred to as black dots, black spots, black speckles, etc. (see, for example, Patent Document 1).

[0003] Specifically, ultraviolet exposure is performed through a photomask with a pattern formed thereon by photolithography technology on the surface of a substrate of glass or plastic material coated with a black photosensitive material such as black resist, etc., and regular protrusions that perform functions such as scales, encoders, and diffraction elements are generally formed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Disclosure of the Invention

Problems to be Solved by the Invention

[0005] By the way, in the formed protrusions, as shown in Fig. 7(a), they swelled elliptically, or as shown in Fig. 7(b), inclinations were likely to exist at the top and the like, which was the cause of scattered light.

[0006] Here, if the black resist is thinly coated, it becomes difficult for inclinations to exist, and thus it is also conceivable to prevent the generation of scattered light thereby.

[0007] However, black photosensitive materials such as black resist used for forming conventional protrusions tended to have a lower optical density as the wavelength dependence became longer. Therefore, in order to block light, a corresponding thickness was required depending on the optical density at the required wavelength.

[0008] That is, simply thinning the protrusions may reduce the light absorptivity, and it may not be possible to use them in applications that require high light absorptivity such as medical and ophthalmic equipment related applications.

[0009] An object of the present invention is to provide a method for manufacturing a light absorber and a light absorber that do not generate scattered light and have high light absorptivity.

Means for Solving the Problems

[0010] As a result of intensive studies to solve the above problems, the present inventor obtained the following findings. That is, when a protrusion-shaped black dot film is formed using a resist for forming a black matrix, it is possible to produce a light absorber having high light absorptivity even at 500 μm or less.

[0011] Based on the findings of the present inventor, the means for solving the above problems of the present invention are as follows.

[0012] <1> A light absorber used for optical elements of medical equipment and ophthalmic equipment, which is a protrusion film formed to protrude from the substrate surface, is made of a resist for forming a black matrix, has a thickness of 500 μm or less from the substrate surface, and has an optical density (OD value) between 350 and 1,350 nm of 3.0 or more. A light absorber characterized by that.

[0013] <2> The light absorber according to <1>, wherein the thickness from the substrate surface is 100 μm or less.

[0014] <3> A method for manufacturing a light absorber used in optical elements of medical devices and spectacle devices, comprising exposing the surface of a substrate coated with a resist for forming a black matrix with at least one of ultraviolet light and laser light to form a black dot-like protrusion film having a thickness of 500 μm or less from the surface of the substrate and an optical density (OD value) between 350 and 1,350 nm of 3.0 or more.

Advantages of the Invention

[0015] Since the light absorber of the present invention is made of a resist for forming a black matrix, even a protrusion film with a thickness of 500 μm or less has high light absorption with an optical density (OD value) between 350 and 1,350 nm of 3.0 or more. Also, since the thickness is 500 μm or less, generation of scattered light can be prevented.

[0016] In the method for manufacturing the light absorber of the present invention, since a black dot-like protrusion film is manufactured by exposing a resist for forming a black matrix, even a protrusion film with a thickness of 500 μm or less can be formed to have high light absorption with an optical density (OD value) between 350 and 1,350 nm of 3.0 or more. Also, since the thickness is 500 μm or less, generation of scattered light can be prevented.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

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Figure 7

Embodiments for Carrying Out the Invention

[0018] The light absorber of the present invention is composed of a resist for forming a black matrix (hereinafter also referred to as "black matrix resist") used when forming a black matrix of a color filter.

[0019] As such a black matrix resist, commercially available products can be appropriately selected and used. For example, CFPK (registered trademark) BK series, WTP BK series manufactured by Tokyo Ohka Kogyo Co., Ltd., and "Espfine" (registered trademark), a black resist manufactured by Nippon Steel Chemical & Material Co., Ltd., are preferably mentioned.

[0020] The black matrix resist appropriately contains components usually used to obtain a photosensitive resin, such as a binder, a polymerizable compound, and a photoinitiator, as necessary. It may also contain a thermal crosslinking agent for forming a solder resist.

[0021] In addition, various known additives such as an antioxidant, an antistatic agent, a surfactant, a flame retardant, and a dispersant may be blended in the black matrix resist within a range that does not inhibit the effects of the present invention.

[0022] In the present invention, a black dot-shaped protrusion film for preventing light reflection is formed by this black matrix resist. Since this protrusion film has light-shielding properties, it functions as a light absorber.

[0023] Specifically, as shown in FIG. 1(a), exposure is performed on the surface of the substrate 10 coated with the black matrix resist to form the protrusion film 11.

[0024] The application of the resist is not particularly limited, and it may be appropriately selected from those commonly used for applying resists, such as spin coaters and spray coaters.

[0025] After performing pre-baking to evaporate the solvent of this resist, the surface of the substrate 10 is exposed. Regarding this pre-baking as well, there is no particular limitation, and it may be appropriately selected from the commonly used apparatuses and methods and carried out.

[0026] Also, the exposure may be ultraviolet (UV) exposure through a photomask, or laser light may be irradiated directly onto the surface of the substrate 10 or through a photomask.

[0027] Among these exposure means, as the photomask, a mask capable of forming a pattern, such as a chromium mask, is preferable. In the case of a chromium mask, it may be a single chromium layer or an antireflection film of chromium oxide (Cr2O3) may be deposited on the chromium layer. Also, a film mask may be used. On the other hand, the laser light may be light of any color, such as white, red, green, or blue.

[0028] On the other hand, as the substrate 10, it may be a glass plate or a transparent resin plate, and usually, the substrate commonly used when exposing the resist may be appropriately selected.

[0029] When using a mask capable of forming a pattern, it can be formed singly as in the example on the right side of Fig. 1(a), or a plurality of protrusion films 11... can be formed regularly as in the example on the left side of the same figure. This regularly formed film can be applied as a scale, an encoder, a diffraction element, etc.

[0030] Also, the light amount can be adjusted. As shown in Fig. 1(b), the light transmittance can be made uniform over the entire surface, for example, 50%. Or, as shown in Fig. 1(c), the light transmittance can be adjusted to be, for example, 50 to 100% by passing through a photomask with different film thicknesses.

[0031] In addition, development and post-baking (fixing) are performed on the protrusion film obtained by exposure. In this case, the methods of development and fixing are not particularly limited, and appropriate conditions may be selected according to the photosensitive material such as the black matrix resist used. At this time, it is preferable to form black dots (also referred to as black spots or black speckles) on a thin glass or transparent resin plate and then attach it to the substrate or lens, as this facilitates the development process.

[0032] As shown in FIGS. 2 and 3, the protrusion film 11 thus obtained is made to have a protrusion thickness t protruding from the surface of the substrate 10 of 500 μm or less. When the thickness t exceeds 500 μm, the protrusion film is likely to have an inclination, which may increase the concern of generating scattered light. That is, since the protrusion film 11 is a thin protrusion film with a protrusion thickness of 500 μm or less, the generation of scattered light can be prevented.

[0033] In addition, the thickness t of the protrusion film 11 is preferably as thin as possible because it can further suppress the generation of scattered light and reduce material costs. It is preferably 100 μm or less, more preferably 10 μm or less, still more preferably 5 μm or less, and extremely preferably 0.3 μm or more and less than 5 μm. However, if it is less than 0.3 μm, it may be difficult to manage the thickness uniformity, etc. If it can be made as thin as about 0.3 μm, it is sufficient as an effect of reducing material costs, and there is no need to make it thinner.

[0034] Here, the thickness t is not particularly limited as long as it is measured by a method known as a film thickness measurement method capable of measuring the thickness in μm units. For example, using an electromagnetic induction (capacitance type) film thickness gauge, the magnetic flux generated by the primary coil in the probe changes the current induced in the secondary coil according to the thickness of the film, and the film thickness of the protrusion film can be measured. Examples of such an apparatus include the film thickness gauge SP-1100D manufactured by Sanko Electronics Laboratory.

[0035] On the other hand, the optical density of the protrusion film 11 is consistently 3.0 or more between 350 and 1,350 nm, preferably 4.0 or more, more preferably 4.5 or more, still more preferably 5.0 or more, and extremely preferably 5.5 or more. If the optical density is less than 3.0, it is insufficient as a performance for use in applications that require high light absorbency, such as medical and ophthalmic equipment-related applications. Also, if it is not consistently 3.0 or more between 350 and 1,350 nm, there will be wavelength dependence where the light absorbency varies depending on the wavelength. In that case, it is also insufficient as a performance for use in applications that require high light absorbency.

[0036] In general black resists, to achieve this optical density, it is necessary to increase the thickness. Then, the film is likely to have an inclination, increasing the risk of generating scattered light, and the material cost also increases. Also, even if the thickness is increased, there is wavelength dependence, and sufficient high light absorbency cannot be achieved depending on the wavelength.

[0037] On the other hand, in the present invention, since the protrusion film is formed using a black matrix resist, a high optical density can be obtained without wavelength dependence even when formed thinly, the risk of generating scattered light is small, and a light absorber that can be used in applications requiring high light absorbency can be obtained at low cost.

[0038] The optical density can be obtained by calculating the OD (Optical Density) value using the following formula from the transmitted light amount and incident light amount at each wavelength using a commercially available optical density meter. Examples of such a device include the ultraviolet-visible spectrophotometer UV-3100 manufactured by Shimadzu Corporation. (Formula) OD(λ) = Log 10 [T(λ) / I(λ)] = Log 10 T(λ) - Log 10 I(λ) In the formula, (λ) is the wavelength, T(λ) is the transmitted light amount in the wavelength band, and I(λ) is the incident light amount in the wavelength band.

[0039] [Other Forms] In addition, the formation of the protruding film may be performed using an inkjet printing technique (inkjet method). As shown in FIG. 4(a), on the surface of the surface-treated substrate 10, an inkjet head H is used to draw an inkjet liquid pattern P using the above-described black matrix resist ink, and then this is cured (dried) to produce a black dot-shaped protruding film 11 that functions as a light absorber, as shown in FIG. 4(b). When the inkjet method is used, since unnecessary materials are not removed, it is possible to produce a light absorber while having no material loss and with further consideration for the environment.

[0040] In addition, as the printing technique, it is not limited to the inkjet method, and for example, a screen printing technique may be used. As shown in FIG. 5(a), through a screen plate S, while applying pressure in the direction of the arrow in the illustrated example with a squeegee (spatula) Q, the ink I of the black matrix resist is extruded, and as shown in FIG. 5(b), the ink I that has passed through the holes of the screen plate S is transferred to the surface of the substrate 10 to produce a protruding film 11. Also in this screen printing, from the viewpoint that unnecessary materials are not removed, it can be preferably used in the same manner as the inkjet method.

[0041] [Examples] In order to verify the difference in light absorption between the present invention and the conventional example, a protruding film having the following thickness was formed, and the optical density (OD) at wavelengths of 350 to 1,400 nm was measured. The results are shown in the graph of FIG. 6. The thickness of each protruding film was measured using a film thickness meter SP-1100D manufactured by Sanko Electronics Laboratory. Also, the OD of each protruding film was measured using an ultraviolet-visible spectrophotometer UV-3100 manufactured by Shimadzu Corporation.

[0042] (The present invention) As the black matrix resist, CFPK (registered trademark) BK series manufactured by Tokyo Ohka Kogyo Co., Ltd. was applied to the surface of the substrate under the conditions of spin coating at 500 rpm for 30 seconds, and the surface of the substrate was exposed to laser light (see FIG. 1(a) etc.), and a protruding film as the light absorber of the present invention having a thickness t (see FIG. 3) of 1 μm from the substrate surface was formed.

[0043] (Conventional Example) Projection films as conventional examples with thicknesses of 20 μm and 50 μm from the substrate surface were formed in the same manner from black resist manufactured by other companies, respectively.

[0044] As shown in FIG. 6, in the projection film of the light absorber of the present invention, despite being extremely thin with a thickness of 1 μm, it had an extremely high light absorbency with an optical density (OD) of 5.5 or more at any wavelength from 350 to 1,400 nm. Therefore, it was found that the light absorber of the present invention is suitable for applications that require high light absorbency, such as medical and ophthalmic equipment-related applications.

[0045] On the other hand, for the light absorber of the projection film of the conventional example, when the thickness was 20 μm, the optical density (OD) was only about 2 even at the wavelength of 350 nm where the optical density was the highest. By increasing the thickness to 50 μm, it was only possible to show 3.0 or more at wavelengths of about 700 nm or less. Also, as the wavelength increased, the optical density decreased and there was a wavelength dependence. Therefore, even if the thickness was increased to 100 μm, it was difficult to show OD 3.0 or more between 350 and 1,400 nm, and it was presumed to be difficult even if the thickness was increased to 500 μm. Therefore, it was found that it could not be used for applications that require high light absorbency at the same thickness as the present invention.

[0046] Thus, since the light absorber of the present invention has high light-shielding properties, it can be suitably used for devices that obtain information using light that requires adjustment of the light amount and optical path, removal of reflected light that causes ghosting and flare, etc., that is, for applications of optical devices. In particular, it can be more suitably used for medical and ophthalmic equipment-related applications that require optical elements that absorb and remove harmful reflected light and scattered light, such as those referred to as black dots, black spots, and speckles, which occur in the cornea and lens of the eye.

[0047] As described above, the embodiments of the present invention have been described in detail. However, the light absorber of the present invention is not limited to the above embodiments and may include any technical idea assumed within the scope thereof. [Industrial Applicability]

[0048] The present invention can be widely used in applications of optical devices such as medical devices that require adjustment of the amount of light and the optical path, and removal of reflected light that causes ghosting and flare.

Explanation of Signs

[0049] 10 Substrate 11 Protrusion film t (thickness of the protrusion film)

Claims

1. A light absorber used for optical elements of medical devices and spectacle devices, The light absorber comprises a substrate and a protruding film formed to protrude on the surface of the substrate, The substrate is made of a glass plate or a transparent resin plate having no relatively large unevenness on the surface compared to the scale of the substrate, The protruding film is formed to protrude only on the central portion along the horizontal direction of the surface of the substrate, and is made of a resist for forming a black matrix which is a black photosensitive resin. The thickness from the substrate surface is 100 μm or less, and the optical density (OD value) between wavelengths of 350 to 1,350 nm is 3.0 or more. The light absorber is characterized in that by forming the protruding film only on the central portion of the substrate surface, it can be applied to the optical element that absorbs and removes harmful reflected light or scattered light generated by the eyes.

2. A method for manufacturing a light absorber used for optical elements of medical devices and spectacle devices, Only the central portion along the horizontal direction of the surface of a substrate made of a glass plate or a transparent resin plate having no relatively large unevenness on the surface, on which a resist for forming a black matrix which is a black photosensitive resin is applied, is exposed by at least one of ultraviolet light and laser light to form a black dot-shaped protruding film on the substrate that functions as a light absorber with a thickness from the substrate surface of 100 μm or less and an optical density (OD value) between wavelengths of 350 to 1,350 nm of 3.0 or more. The method for manufacturing a light absorber is characterized in that by forming the protruding film only on the central portion of the substrate surface, it can be applied to the optical element that absorbs and removes harmful reflected light or scattered light generated by the eyes.

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