JP2010139959A - Plastic rod lens, method of manufacturing the same, and plastic rod lens array - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lens array having heat resistance which has high resolution and suppresses change in a conjugate length even if the lens array is used under a high temperature environment, and to provide a rod lens used for the array. <P>SOLUTION: A plastic rod lens has a columnar shape, and has a refractive index that continuously decreases from the center to the outer circumference. The lens material includes a polymer substance produced by polymerizing a mixture of polymer (A) mainly made of maleimido-based monomer and a radical polymerizable vinyl monomer (B) compatible with the polymer (A) mainly made of maleimido-based monomer. In the plastic rod lens that has a columnar shape and has a refractive index that continuously decreases from the center to the outer circumference, the content of the polymer substance is more in the center of the rod lens than in the outer circumference thereof. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a plastic rod lens array used as an optical transmission body of a scanner, an image sensor, a printer or the like, and a plastic rod lens used therefor.

  A plastic rod lens (hereinafter simply referred to as a “rod lens”) is a cylindrical lens having a refractive index distribution in which the refractive index continuously decreases from the center toward the outer peripheral portion. A rod lens array (hereinafter, simply referred to as “lens array”) made of plastic rods is arranged and bonded and fixed in one or more rows so that the central axes of the rod lenses are substantially parallel to each other between the two substrates. Are widely used in various scanners such as hand scanners, parts for image sensors in copiers and facsimiles, writing devices such as LED printers, and the like.

  Polymethyl methacrylate is generally used as the main material for plastic rod lenses, but since polymethyl methacrylate has a low glass transition temperature (Tg), the conjugation length easily changes in a high temperature environment. The heat resistance of the lens is insufficient.

  In order to facilitate handling of the rod lens at the time of manufacturing the lens array, it is required to increase the mechanical strength of the rod lens. In order to improve this, Patent Documents 1 and 2 disclose a method of heating and relaxing the rod lens by heating. However, a rod lens that has been heat-stretched and relaxed has a large thermal shrinkage, and when used in a high temperature environment, the rod lens shrinks due to heat and the conjugate length changes, so the resolution (MTF: Moderation Transfer Function) There was a risk of falling.

  In particular, when such a rod lens is used as a lens array in an image sensor or LED printer having a high resolution of 600 dpi or more, this problem becomes serious.

Therefore, as a method for providing a rod lens array that has heat resistance that hardly causes a change in conjugate length even when used in a high temperature environment and has excellent resolution, in Patent Document 3, heat treatment is performed after relaxing and stretching the rod lens. A method is disclosed. However, even with this method, the heat resistance of the obtained rod lens was not sufficient.
Japanese Patent Laid-Open No. 8-21242 JP 2001-337244 A JP 2007-34259 A

  An object of the present invention is to provide a lens array having heat resistance that hardly causes a change in conjugate length even when used in a high temperature environment, and excellent in resolution, and a rod lens used therefor.

  The inventors of the present invention shaped an uncured material containing a polymer (A) containing a maleimide monomer as a main component into a filamentous material in such an arrangement that the refractive index gradually decreases from the center toward the outer periphery. Then, after performing the interdiffusion treatment of the material between the adjacent layers so that the refractive index distribution between the respective layers in the thread state is continuous, by using a plastic rod lens obtained by curing the filamentous body, The inventors have found that the problem can be solved and have reached the present invention.

  That is, the present invention forms an uncured material containing a polymer (A) containing a maleimide monomer as a main component into a filamentous material in such an arrangement that the refractive index decreases sequentially from the center toward the outer periphery. This is a plastic rod lens obtained by performing a mutual diffusion treatment of materials between adjacent layers so that the refractive index distribution between the respective layers in the thread state is continuous, and then curing the filamentous body under a high temperature environment. Even when used in the above, the resolution can be kept high since the contraction of the rod lens and the change in conjugate length due to heat are small.

  Furthermore, the present invention can provide a lens array having excellent heat resistance characteristics that does not deteriorate optical characteristics such as resolution even when used in a high temperature environment in an image sensor or LED printer having a high resolution of 600 dpi or more. .

  The rod lens array according to the present invention is excellent in heat resistance because deterioration and variation in optical characteristics such as resolution are suppressed even when used in a high temperature environment.

  Hereinafter, preferred embodiments of the present invention will be described in detail.

The plastic rod lens of the present invention is a cylindrical lens having a refractive index distribution in which the refractive index continuously decreases from the center toward the outer periphery. As the refractive index distribution, when the radius of the rod lens is r in a cross section perpendicular to the central axis of the rod lens, the refractive index distribution in the range of 0.3r to 0.7r at least from the central axis toward the outer periphery is as follows. It is preferable to approximate a quadratic curve distribution defined by the following formula (1).
^{_{n (L) = n 0 {}} 1- (g 2/2) L 2} (1)
(Where n ₀ is the refractive index (central refractive index) at the central axis of the rod lens, L is the distance from the central axis of the rod lens (0 ≦ L ≦ r), and g is the refractive index of the rod lens. (It is a distribution constant, and n (L) is a refractive index at a position of a distance L from the central axis of the rod lens.)
The radius r of the rod lens is not particularly limited, but the radius r is preferably small from the viewpoint of compacting the optical system, and the radius r is preferably large from the viewpoint of handling during processing of the rod lens. For this reason, the radius r of the rod lens is preferably in the range of 0.05 to 1 mm, more preferably in the range of 0.1 to 0.5 mm.

Further, by setting the refractive index n ₀ of the central axis of the rod lens to 1.4 to 1.6, the choice of materials constituting the rod lens can be widened, and a favorable refractive index distribution can be easily formed. Become.

Further, the refractive index distribution constant g of the rod lens is not particularly limited, but is in the range of 0.2 to 3 mm ⁻¹ from the viewpoint of compacting the optical system, ensuring the working distance of the optical system, and handling. More preferably, it is the range of 0.5-2 mm < ^-1 >.

  Moreover, it is preferable that the rod lens is provided with a light absorption layer containing a light absorber that absorbs at least a part of light transmitted through the rod lens on an outer peripheral portion of 0.6r or more from the central axis. In general, with a rod lens, an irregular portion in which the refractive index distribution deviates from the ideal distribution tends to be formed as the distance from the central axis increases, and the optical characteristics due to this are absorbed by the outer periphery of the rod lens. This is because it is suppressed by providing a layer. The thickness of the light absorption layer is preferably 50 μm or more and 100 μm or less. By setting the thickness of the light absorption layer within this range, flare light and crosstalk light can be sufficiently removed and a sufficient amount of transmitted light can be secured.

  As a light absorber to be used, a light source that emits light having a wavelength of 400 to 900 nm is generally used as a light source in an image sensor, an LED printer, or the like, and light in at least a part of the wavelength region of 400 to 900 nm. It is preferable to use one that absorbs. As such a light absorber, for example, Kayasorb CY-10 manufactured by Nippon Kayaku which absorbs in the 600 nm to near infrared region, Diaresin Blue 4G manufactured by Mitsubishi Chemical which absorbs at 600 to 700 nm, and the like are absorbed at 550 to 650 nm. Examples include Kayset Blue ACR made by Nippon Kayaku, etc., Mitsui Toatsu dye MS Magenta HM-1450, which absorbs at 500 to 600 nm, Mitsui Toatsu dye MS Yellow HD-180, which absorbs at 400 to 500 nm, etc. Can do. Moreover, a black dye etc. can be mentioned as a light absorber which absorbs the light of all the wavelength ranges among 400-900 nm. These light absorbers may be used alone or in combination of two or more.

  Next, a method for manufacturing the above rod lens will be described.

  There is no limitation on the method of forming the refractive index distribution of the rod lens, and any method such as an addition reaction method, a copolymerization method, a gel polymerization method, a monomer volatilization method, and an interdiffusion method may be used. In this respect, the interdiffusion method is preferable. The mutual diffusion method will be described below.

First, N uncured products having a refractive index n after curing satisfying n ₁ > n ₂ >...> _{N N} (N ≧ 3) are gradually decreased from the center toward the outer periphery. In such an arrangement, it is shaped into an uncured laminated body (hereinafter referred to as “filamentous body”) that is concentrically laminated, and adjacent so that the refractive index distribution between each layer of the filamentous body is continuous. While performing the interdiffusion treatment of the substances between the layers or after the mutual diffusion treatment, the filamentous body is cured to obtain a rod lens raw yarn (spinning step). The interdiffusion treatment refers to giving the filament a thermal history of several seconds to several minutes at 10 to 60 ° C., more preferably 20 to 50 ° C., under a nitrogen atmosphere.

  Examples of the substance constituting the uncured product include a mixture containing at least a polymer (A) containing a maleimide monomer as a main component and a radical polymerizable vinyl monomer (B).

  Specific examples of the polymer (A) based on maleimide monomers include N-phenylmaleimide monomer, N-phenylmaleimide and styrene / methyl methacrylate copolymer, N-phenylmaleimide and styrene copolymer. Polymer, copolymer of N-phenylmaleimide and styrene and acrylonitrile, monomer of N-cyclohexylmaleimide, copolymer of N-cyclohexylmaleimide and styrene and methyl methacrylate, copolymer of N-cyclohexylmaleimide and styrene , A copolymer of N-cyclohexylmaleimide and styrene and acrylonitrile.

  Moreover, the ratio contained in the said mixture of the polymer (A) which has a maleimide-type monomer as a main component is 30-70 mass parts with respect to 100 mass parts of mixtures from a viewpoint of the viscosity for obtaining a rod lens raw yarn. It is preferable that

  Specific examples of the radical polymerizable vinyl monomer (B) include methyl methacrylate (n = 1.49), styrene (n = 1.59), chlorostyrene (n = 1.61), vinyl acetate (n = 1). .47), 2,2,3,3-tetrafluoropropyl (meth) acrylate, 2,2,3,3,4,4,5,5-octafluoropentyl (meth) acrylate, 2,2,3, Fluorinated alkyl (meth) acrylates such as 4,4,4-hexafluorobutyl (meth) acrylate and 2,2,2-trifluoroethyl (meth) acrylate (n = 1.37 to 1.44), refractive index 1.43-1.62 (meth) acrylates such as ethyl (meth) acrylate, phenyl (meth) acrylate, benzyl (meth) acrylate, hydroxyalkyl (meth) acrylate Rate, alkylene glycol (meth) acrylate, trimethylolpropane di- or tri (meth) acrylate, pentaerythritol di, tri- or tetra (meth) acrylate, diglycerin tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, etc. Other diethylene glycol bisallyl carbonates, fluorinated alkylene glycol poly (meth) acrylates and the like can be mentioned.

  The radical polymerizable vinyl monomer (B) to be used must be compatible with the polymer (A) mainly composed of a maleimide monomer, and the radical polymerizable vinyl monomer constituting the polymer is used. It is more preferable to use at least one kind of (B).

  In order to easily adjust the viscosity of the uncured material when forming the filament from these uncured materials, and to have a continuous refractive index distribution from the center to the outer periphery of the filament, The product is preferably composed of the polymer and a vinyl monomer.

  In order to adjust the viscosity, it is preferable to use a polymer having the same refractive index in each layer as the polymer because a plastic optical transmission body having a continuous refractive index distribution from the center toward the outer periphery can be obtained.

  In order to cure the filament formed from the uncured product, a thermosetting catalyst or a photocuring catalyst is added to the uncured product, and a thermosetting process and / or a photocuring process is performed. As the thermosetting catalyst, a peroxide-based or azo-based catalyst or the like is used. Photocuring catalysts include benzophenone, benzoin alkyl ether, 4'-isopropyl-2-hydroxy-2-methylpropiophenone, 1-hydroxycyclohexyl phenyl ketone, benzyl methyl ketal, 2,2-diethoxyacetophenone, chlorothioxanthone, thioxanthone Compounds, benzophenone compounds, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, N-methyldiethanolamine, triethylamine and the like.

  The photocuring treatment can be performed by irradiating an uncured material containing a photocuring catalyst with ultraviolet rays from the surroundings. Examples of the light source used for the photocuring treatment include a carbon arc lamp that generates light having a wavelength of 150 to 600 nm, a high-pressure mercury lamp, a medium-pressure mercury lamp, a low-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a chemical lamp, a xenon lamp, and a laser beam. Further, these light sources may be used in appropriate combination in order to increase the polymerization rate. Thus, a rod lens containing a polymer of a mixture containing a polymer (A) containing a maleimide monomer as a main component and a radical polymerizable vinyl monomer (B) can be obtained.

  The thermosetting treatment is preferably performed by heating an uncured product containing a thermosetting catalyst for a predetermined time in a curing processing section such as a heating furnace controlled at a constant temperature. The rod lens yarn obtained in this way becomes a first plastic rod lens through a stretching process and a relaxation process. Stretching can be performed by a known method. For example, the rod lens raw yarn obtained by curing is supplied to a heating furnace with a first nip roller, and the rod lens that has passed through the heating furnace is drawn with a second nip roller at a higher speed than the first nip roller and drawn. Methods and the like.

  The atmospheric temperature (stretching temperature) in the stretching step is set according to the material of the rod lens and the like, but the glass transition temperature (Tg) of the rod lens yarn is preferably + 20 ° C. or more, and preferably Tg + 60 ° C. or less. In addition, when a rod lens is comprised with multiple types of material, let the maximum value of those Tg be Tg of a rod lens.

  Moreover, although a draw ratio is determined by a desired rod lens diameter and can be adjusted by a speed ratio of the first and second nip rollers, 1.1 to 10 times is preferable, and 2 to 6 times is more preferable.

  The relaxation can be performed by a known method. For example, there is a method in which the drawn rod lens yarn is supplied to a heating furnace with a third nip roller, and the rod lens that has passed through the heating furnace is pulled off with a fourth nip roller at a slower speed than the third nip roller, etc. Can be mentioned.

  The ambient temperature (relaxation temperature) in the relaxation process is set according to the material of the rod lens and the like, but considering the optical characteristics of the rod lens array using the obtained rod lens, it is preferably Tg or more and Tg + 60 ° C. or less. Tg or more and a stretching temperature of −5 ° C. or less are more preferable.

  Further, the relaxation magnification is determined by the desired rod lens diameter and can be adjusted by the speed ratio of the third and fourth nip rollers, but is preferably 0.5 or more and less than 1 time, 0.6 to 0.9 Double is more preferred.

  The stretching step may be performed in a batch manner or continuously. Further, the stretching step and the relaxation step may be performed continuously, or may be performed separately for each step. From the viewpoint of productivity, it is preferable to carry out continuously.

  The first rod lens having a desired diameter through the stretching and relaxation processes may be continuously cut to a desired length, or may be cut after being wound around a bobbin or the like.

  The substrate constituting the lens array of the present invention may have a flat plate shape, or may have a U-shaped or V-shaped groove for arranging and storing rod lenses at a constant interval. Although the material of a board | substrate is not specifically limited, It is preferable that it is a material easy to process in the process of producing a lens array. As the material for the substrate, various thermoplastic resins, various thermosetting resins, and the like are preferable, and acrylic resins, ABS resins, polyimide resins, liquid crystal polymers, epoxy resins, and the like are particularly preferable. Further, fibers or paper may be used as the base material and reinforcing material of the substrate, and a release agent, a dye, a pigment, and the like may be added to the substrate.

  The adhesive is not particularly limited as long as it has an adhesive strength enough to attach the lens array and the substrate or between the lens arrays. A melt-type pressure-sensitive adhesive or the like can be used. In addition, as a method of applying the adhesive to the substrate or the lens array, a known coating method such as a screen printing method or a spray coating method can be used depending on the type of the adhesive.

Hereinafter, the present invention will be described specifically by way of examples.
<Refractive index distribution>
The measurement was performed using an Interfaco interference microscope manufactured by Carl Zeiss.
<Conjugate length and resolution (average MTF, MTF standard deviation)>
Using a grating pattern having a spatial frequency of 12 (line pair / mm, Lp / mm), light (525 nm) from a light source is incident on the rod lens array whose both ends perpendicular to the optical axis are polished through the grating pattern to form an image. The lattice image is read by a CCD line sensor installed on the surface, the maximum (imax) and minimum (imin) of the measured light intensity are measured, and the MTF (moderation transfer function) is obtained by the following equation (2). It was.
MTF (%) = {(imax−imin) / (imax + imin)} × 100 (2)
At that time, the distance between the grating pattern and the entrance end of the rod lens array and the distance between the exit end of the rod lens array and the CCD line sensor were made equal. Then, the MTF was measured by moving the grating pattern and the CCD line sensor symmetrically with respect to the rod lens array, and the distance between the grating pattern and the CCD line sensor when the MTF was the best was defined as the conjugate length.

The distance between the lattice pattern and the CCD line sensor was fixed at a conjugate length, and the entire width of the rod lens array was scanned to measure 50 MTFs, and the average value and standard deviation were obtained to obtain resolution and its variation index. Here, the spatial frequency indicates a combination of white lines and black lines as one line, and indicates how many combinations of these lines are provided within a width of 1 mm.
<Heat resistance test>
The rod lens array was placed in a dryer set at 80 ° C. (relative humidity of 30% or less) and held for 1000 hours. The conjugate length, MTF average value, and standard deviation before and after the test were determined. The case where the change in the conjugate length [mm] after the test was within ± 0.2 mm was evaluated as ◎, the case where ± 0.3 mm to ± 0.4 mm was given, and the case where it was ± 0.5 mm or more were evaluated as ×. Further, the case where the average MTF [%] after the test was 70% or more was evaluated as ◎, the case of 60 to 70% was evaluated as ○, and the case of 60% or less was evaluated as ×. Further, the case where the MTF standard deviation [%] after the test was 4% or less was evaluated as ◎, the case where it was 5 to 6% was evaluated as ○, and the case where it was 7% or more was evaluated as ×.
<Example 1>
37 parts by mass of a copolymer consisting of 30 parts by mass of N-phenylmaleimide, 40 parts by mass of methyl methacrylate and 30 parts by mass of styrene, tricyclo [5.2.1.0 ^2, represented by the following formula (Formula 1) ⁶ ] 30 parts by mass of decanyl-8-methacrylate (TCDMA), 33 parts by mass of methyl methacrylate (MMA), 0.25 part by mass of 1-hydroxycyclohexyl phenyl ketone and 0.1 part by mass of hydroquinone (HQ) are heated and kneaded at 70 ° C. Thus, a first layer forming stock solution was obtained.

Ｎ‐フェニルマレイミド３０質量部、メタクリル酸メチル４０質量部、スチレン３０質量部から成る共重合ポリマー４０質量部、ＴＣＤＭＡ１０質量部、ＭＭＡ５０質量部、１−ヒドロキシシクロヘキシルフェニルケトン０．２５質量部及びＨＱ０．１質量部を７０℃に加熱混練して第２層形成用原液とした。

30 parts by mass of N-phenylmaleimide, 40 parts by mass of methyl methacrylate, 40 parts by mass of a copolymer consisting of 30 parts by mass of styrene, 10 parts by mass of TCDMA, 50 parts by mass of MMA, 0.25 parts by mass of 1-hydroxycyclohexyl phenyl ketone and HQ0. One part by mass was heated and kneaded at 70 ° C. to obtain a second layer forming stock solution.

  Copolymer polymer composed of 30 parts by weight of N-phenylmaleimide, 40 parts by weight of methyl methacrylate and 30 parts by weight of styrene, 2,2,3,3,4,4,5,5-octafluoropentyl methacrylate (8FM) ) 10 parts by mass, MMA 50 parts by mass, 1-hydroxycyclohexyl phenyl ketone 0.25 part by mass, and HQ 0.1 part by mass were heated and kneaded at 70 ° C. to obtain a third layer forming stock solution.

  30 parts by mass of N-phenylmaleimide, 40 parts by mass of methyl methacrylate, 40 parts by mass of copolymer, 30 parts by mass of styrene, 10 parts by mass of 8FM, 50 parts by mass of MMA, 0.25 parts by mass of 1-hydroxycyclohexyl phenyl ketone, HQ0. 1 part by mass was heated and kneaded at 70 ° C. to obtain a fourth layer forming stock solution.

  30 parts by mass of N-phenylmaleimide, 40 parts by mass of methyl methacrylate, 32 parts by mass of a copolymer consisting of 30 parts by mass of styrene, 28 parts by mass of MMA, 40 parts by mass of 8FM, 0.25 parts by mass of 1-hydroxycyclohexyl phenyl ketone, HQ0. One part by mass was heated and kneaded at 70 ° C. to obtain a fifth layer forming stock solution.

  In addition, in order to suppress crosstalk light and flare light, dye Blue ACR (manufactured by Nippon Kayaku Co., Ltd.) 0. 57% by mass, dyes MS Yellow HD-180 (Mitsui Toatsu Dye Co., Ltd.) and MS Magenta HM-1450 (Mitsui Toatsu Dye Co., Ltd.) 0.14% by mass, dye Diaresin Blue 4G (Mitsubishi) Chemical Co., Ltd.) and Kayasorb CY-10 (Nippon Kayaku Co., Ltd.) were added in an amount of 0.02% by mass.

  These five types of stock solutions were sequentially arranged from the center so that the refractive index after curing was lowered and simultaneously extruded from a concentric five-layer composite spinning nozzle. The temperature of the composite spinning nozzle was 54 ° C. The ejection ratio of each layer is converted into the ratio of the thickness of each layer in the diameter direction of the lens (the radius in the first layer). First layer / 2nd layer / 3rd layer / 4th layer / 5th layer = 18/50/29/2/1.

  Next, the filaments extruded from the composite spinning nozzle are taken up by a nip roller (200 cm / min), passed through an interdiffusion treatment section having a length of 30 cm, and subsequently, 18 chemical lamps having a length of 120 cm and 40 W have a central axis. A first curing processing unit (light irradiation unit) disposed at equal intervals around the periphery and a second curing processing unit (light irradiation unit) in which three 2 KW high-pressure mercury lamps are disposed at equal intervals around the central axis. The filament was passed through the center and cured. The nitrogen flow rate in the interdiffusion treatment part was 72 L / min. The radius of the obtained lens yarn was 0.30 mm, and Tg was 130 ° C.

  This lens raw yarn is continuously stretched 3.8 times in a 160 ° C. atmosphere (stretching roller speed of 750 cm / min) from the spinning process, and the relaxation rate becomes 12/15 in a 135 ° C. atmosphere. In this manner, relaxation treatment (relaxation roller speed 600 cm / min) was performed, and the cutting process was performed to cut a length of 166 mm to obtain a large number of rod lenses (first rod lenses) having a length of 166 mm.

The obtained first rod lens has a radius of 0.17 mm, a central refractive index of 1.5120, and a refractive index distribution that approximates Equation (1) in the range of 0.2r to 0.8r from the central axis toward the outer periphery. The refractive index distribution constant g was 0.84 mm ⁻¹ at a wavelength of 525 nm. In addition, a layer having a thickness of about 5 μm from the outer peripheral surface of the first rod lens toward the center and a substantially uniform mixture of dyes was formed.

A number of the first rod lenses were used to produce a single-row rod lens array (lens length 4.4 mm) with an arrangement pitch of 0.36 mm (gap between adjacent lenses 20 μm). The conjugate length, MTF average value, and standard deviation at 525 nm of the prepared rod lens array were measured before and after the heat resistance test, and are summarized in Table 1.
<Example 2>
Copolymer polymer 37 parts by weight of N-cyclohexylmaleimide 30 parts by weight, methyl methacrylate 40 parts by weight, styrene 30 parts by weight, tricyclo [5.2.1.0 ^2,6 ] decanyl-8-methacrylate (TCDMA) 30 Mass parts, 33 parts by mass of methyl methacrylate (MMA), 0.25 parts by mass of 1-hydroxycyclohexyl phenyl ketone and 0.1 parts by mass of hydroquinone (HQ) were heated and kneaded at 70 ° C. to obtain a stock solution for forming the first layer.

  30 parts by mass of N-cyclohexylmaleimide, 40 parts by mass of methyl methacrylate, 40 parts by mass of a copolymer consisting of 30 parts by mass of styrene, 10 parts by mass of TCDMA, 50 parts by mass of MMA, 0.25 parts by mass of 1-hydroxycyclohexyl phenyl ketone and HQ0. One part by mass was heated and kneaded at 70 ° C. to obtain a second layer forming stock solution.

  Copolymer polymer composed of 30 parts by mass of N-cyclohexylmaleimide, 40 parts by mass of methyl methacrylate and 30 parts by mass of styrene, 2,2,3,3,4,4,5,5-octafluoropentyl methacrylate (8FM ) 10 parts by mass, MMA 50 parts by mass, 1-hydroxycyclohexyl phenyl ketone 0.25 part by mass, and HQ 0.1 part by mass were heated and kneaded at 70 ° C. to obtain a third layer forming stock solution.

  30 parts by mass of N-cyclohexylmaleimide, 40 parts by mass of methyl methacrylate, 40 parts by mass of copolymer consisting of 30 parts by mass of styrene, 10 parts by mass of 8FM, 50 parts by mass of MMA, 0.25 parts by mass of 1-hydroxycyclohexyl phenyl ketone, HQ0. 1 part by mass was heated and kneaded at 70 ° C. to obtain a fourth layer forming stock solution.

  30 parts by mass of N-cyclohexylmaleimide, 40 parts by mass of methyl methacrylate, 32 parts by mass of a copolymer consisting of 30 parts by mass of styrene, 28 parts by mass of MMA, 40 parts by mass of 8FM, 0.25 parts by mass of 1-hydroxycyclohexyl phenyl ketone, HQ0. One part by mass was heated and kneaded at 70 ° C. to obtain a fifth layer forming stock solution.

  In addition, in order to suppress crosstalk light and flare light, dye Blue ACR (manufactured by Nippon Kayaku Co., Ltd.) 0. 57% by mass, dyes MS Yellow HD-180 (Mitsui Toatsu Dye Co., Ltd.) and MS Magenta HM-1450 (Mitsui Toatsu Dye Co., Ltd.) 0.14% by mass, dye Diaresin Blue 4G (Mitsubishi) Chemical Co., Ltd.) and Kayasorb CY-10 (Nippon Kayaku Co., Ltd.) were added in an amount of 0.02% by mass.

  These five types of stock solutions were sequentially arranged from the center so that the refractive index after curing was lowered and simultaneously extruded from a concentric five-layer composite spinning nozzle. The temperature of the composite spinning nozzle was 54 ° C. The ejection ratio of each layer is converted into the ratio of the thickness of each layer in the diameter direction of the lens (the radius in the first layer). First layer / 2nd layer / 3rd layer / 4th layer / 5th layer = 18/50/29/2/1.

  Next, the filaments extruded from the composite spinning nozzle are taken up by a nip roller (200 cm / min), passed through an interdiffusion treatment section having a length of 30 cm, and subsequently, 18 chemical lamps having a length of 120 cm and 40 W have a central axis. A first curing processing unit (light irradiation unit) disposed at equal intervals around the periphery and a second curing processing unit (light irradiation unit) in which three 2 KW high-pressure mercury lamps are disposed at equal intervals around the central axis. The filament was passed through the center and cured. The nitrogen flow rate in the interdiffusion treatment part was 72 L / min. The radius of the obtained lens yarn was 0.30 mm, and Tg was 130 ° C.

  This lens raw yarn is continuously stretched 3.8 times in a 160 ° C. atmosphere (stretching roller speed of 750 cm / min) from the spinning process, and the relaxation rate becomes 12/15 in a 135 ° C. atmosphere. In this manner, relaxation treatment (relaxation roller speed 600 cm / min) was performed, and in the cutting step, a length of 166 mm was cut to obtain many 166 mm length rod lenses (first rod lenses).

The obtained first rod lens has a radius of 0.17 mm, a central refractive index of 1.5120, and a refractive index distribution that approximates Equation (1) in the range of 0.2r to 0.8r from the central axis toward the outer periphery. The refractive index distribution constant g was 0.84 mm ⁻¹ at a wavelength of 525 nm. In addition, a layer having a thickness of about 5 μm from the outer peripheral surface of the first rod lens toward the center and a substantially uniform mixture of dyes was formed.

A number of the first rod lenses were used to produce a single-row rod lens array (lens length 4.4 mm) with an arrangement pitch of 0.36 mm (gap between adjacent lenses 20 μm). The conjugate length, MTF average value, and standard deviation at 525 nm of the prepared rod lens array were measured before and after the heat resistance test, and are summarized in Table 1.
<Comparative Example 1>
Polymethyl methacrylate (PMMA, [η] = 0.40, measured in MEK at 25 ° C.) 47 parts by mass, tricyclo [5.2.1.0 ^2,6 ] decanyl-8-methacrylate (TCDMA) 30 Mass parts, 23 parts by mass of methyl methacrylate (MMA), 0.25 parts by mass of 1-hydroxycyclohexyl phenyl ketone and 0.1 parts by mass of hydroquinone (HQ) were heated and kneaded at 70 ° C. to obtain a stock solution for forming the first layer.

  50 parts by mass of PMMA, 10 parts by mass of TCDMA, 40 parts by mass of MMA, 0.25 part by mass of 1-hydroxycyclohexyl phenyl ketone and 0.1 part by mass of HQ were heated and kneaded at 70 ° C. to obtain a stock solution for forming the second layer.

  50 parts by mass of PMMA, 10 parts by mass of 2,2,3,3,4,4,5,5-octafluoropentyl methacrylate (8FM), 40 parts by mass of MMA, 0.25 parts by mass of 1-hydroxycyclohexyl phenyl ketone, HQ0.1 A mass part was heated and kneaded at 70 ° C. to obtain a third layer forming stock solution.

  50 parts by mass of PMMA, 10 parts by mass of 8FM, 40 parts by mass of MMA, 0.25 part by mass of 1-hydroxycyclohexyl phenyl ketone, and 0.1 part by mass of HQ were heated and kneaded at 70 ° C. to obtain a fourth layer forming stock solution.

  42 parts by mass of PMMA, 18 parts by mass of MMA, 40 parts by mass of 8FM, 0.25 part by mass of 1-hydroxycyclohexyl phenyl ketone and 0.1 part by mass of HQ were heated and kneaded at 70 ° C. to obtain a stock solution for forming the fifth layer.

  In addition, in order to suppress crosstalk light and flare light, dye Blue ACR (manufactured by Nippon Kayaku Co., Ltd.) 0. 57% by mass, dyes MS Yellow HD-180 (Mitsui Toatsu Dye Co., Ltd.) and MS Magenta HM-1450 (Mitsui Toatsu Dye Co., Ltd.) 0.14% by mass, dye Diaresin Blue 4G (Mitsubishi) Chemical Co., Ltd.) and Kayasorb CY-10 (Nippon Kayaku Co., Ltd.) were added in an amount of 0.02% by mass.

  These five types of stock solutions were sequentially arranged from the center so that the refractive index after curing was lowered and simultaneously extruded from a concentric five-layer composite spinning nozzle. The temperature of the composite spinning nozzle was 54 ° C. The ejection ratio of each layer is converted into the ratio of the thickness of each layer in the diameter direction of the lens (the radius in the first layer). First layer / 2nd layer / 3rd layer / 4th layer / 5th layer = 18/50/29/2/1.

  Next, the filaments extruded from the composite spinning nozzle are taken up by a nip roller (200 cm / min), passed through an interdiffusion treatment section having a length of 30 cm, and subsequently, 18 chemical lamps having a length of 120 cm and 40 W have a central axis. A first curing processing unit (light irradiation unit) disposed at equal intervals around the periphery and a second curing processing unit (light irradiation unit) in which three 2 KW high-pressure mercury lamps are disposed at equal intervals around the central axis. The filament was passed through the center and cured. The nitrogen flow rate in the interdiffusion treatment part was 72 L / min. The radius of the obtained lens yarn was 0.30 mm, and Tg was 110 ° C.

  This lens yarn is continuously stretched 3.8 times in a 140 ° C. atmosphere from the spinning step (stretching roller speed 750 cm / min), and the relaxation rate becomes 12/15 in a 115 ° C. atmosphere. In this manner, relaxation treatment (relaxation roller speed 600 cm / min) was performed, and the cutting process was performed to cut a length of 166 mm to obtain a large number of rod lenses (first rod lenses) having a length of 166 mm.

The obtained first rod lens has a radius of 0.17 mm, a central refractive index of 1.497, and a refractive index distribution that approximates Equation (1) in the range of 0.2r to 0.8r from the central axis toward the outer periphery. The refractive index distribution constant g was 0.84 mm ⁻¹ at a wavelength of 525 nm. In addition, a layer having a thickness of about 5 μm from the outer peripheral surface of the first rod lens toward the center and a substantially uniform mixture of dyes was formed.

  A large number of the second rod lenses were used to produce a single-row rod lens array with a pitch of 0.36 mm (gap 20 μm between adjacent lenses) (lens length 4.4 mm). The conjugate length, MTF average value, and standard deviation at 525 nm of the prepared rod lens array were measured before and after the heat resistance test, and are summarized in Table 1.

実施例１及び実施例２のロッドレンズアレイはいずれも耐熱試験後においても共役長、平均ＭＴＦ値、ＭＴＦ標準偏差が良好であった。

Both the rod lens arrays of Example 1 and Example 2 had good conjugate length, average MTF value, and MTF standard deviation even after the heat test.

  In contrast, the rod lens array of Comparative Example 1 did not have the above properties after the heat resistance test.

Claims (3)

  A plastic rod lens obtained by polymerization with a mixture of a polymer (A) containing a maleimide monomer as a main component and a radical polymerizable vinyl monomer (B). A cylindrical rod lens whose refractive index decreases from the center toward the outer periphery,
The rod lens includes a polymer of a mixture containing a polymer (A) containing a maleimide monomer as a main component and a radical polymerizable vinyl monomer (B) having compatibility with the maleimide monomer,
The maleimide monomer is contained in an amount of 30 to 70 parts by mass with respect to 100 parts by mass of the mixture.
The rod lens, wherein the polymer is contained more in the center of the optical transmission body than the outer periphery of the rod lens.   A rod lens array in which a plurality of the plastic rod lenses according to claim 1 are arranged and fixed between two substrates so that the central axes of the rod lenses are substantially parallel to each other. A plastic rod lens array comprising at least one row.