JP2004341510A - Method for manufacturing plastic rod lens and method for supplying unhardened viscous material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for efficiently and stably manufacturing a plastic rod lens having predetermined conjugate length. <P>SOLUTION: After a plurality of kinds of unhardened viscous material being the material of the plastic rod lens and having predetermined viscosity are preliminarily stirred, they are cooled and charged to the preliminary hopper 12 of a kneading unit 1 by a plurality of times in parts. Then, the unhardened viscous material moved from the hopper 12 to a hopper 11 is supplied to a kneading machine 10 while it is stirred by a stirring blade under predetermined stirring temperature in the hopper 11. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a plastic rod lens, a method for supplying an uncured viscous material that is a raw material for a rod lens, and a kneading unit for kneading the uncured viscous material, and particularly relates to a plastic having a predetermined conjugate length. The present invention relates to a technique for efficiently and stably manufacturing a rod lens.

  Conventionally, a glass rod lens having a continuous refractive index distribution inside has been proposed (for example, see Patent Document 1). Further, a plastic rod lens has also been proposed (for example, see Patent Documents 2, 3, or 4).

  In a conventional method of manufacturing a rod lens made of plastic, an uncured viscous material, which is a material of a rod lens, is supplied from a hopper tank to a kneading machine, kneaded by the kneading machine, and then supplied to a concentric composite spinning nozzle to form a filament ( (Strand fiber). Then, the spun filament is cut into a predetermined length to obtain a rod lens. Furthermore, usually, both end surfaces of the rod lens are mirror-polished so as to be a parallel plane perpendicular to the central axis.

  The rod lens is used alone as a micro lens, and is also used as an integrated rod lens array in which a plurality of rod lenses are adhered in a closely arranged state. A rod lens array is widely used as an optical component of a line sensor in a copying machine, a facsimile, a scanner, and the like, and is also widely used as an optical component such as a writing device of an LED printer.

JP-B-47-816 JP-B-47-28059 International Publication WO9105274 International Publication WO9105275 Proceedings of the 17th Summer Seminar of the Japan Society of Applied Physics / Optical Society, 1979, p. 1 to p. 27 “Design of Lens and Optical System”

  However, in the conventional manufacturing method, the conjugate length varies even if the rod lens is manufactured continuously. The conjugate length is a distance between an image plane positioned across the rod lens and an image plane of the same magnification. The larger the fluctuation width of the conjugate length of the rod lens, the lower the resolution of the rod lens array.

  On the other hand, in recent years, higher resolution has been required for rod lens arrays. In order to realize higher resolution, it is necessary to make the conjugate length of each rod lens constituting the rod lens array more uniform.

Here, the conjugate length Tc will be described with reference to Non-Patent Document 1.
The conjugate length Tc of the rod lens array is given by the following equation (1).
Tc = Z ₀ − (2 / (n ₀ * g)) * tan ((Z ₀ * g) / 2) (1)
Here, Z ₀ is the length of the rod lens.

Further, g in the above equation (1) is a focusing parameter, and the focusing parameter g of a square distribution medium such as a rod lens is given by the following equation (2).
_{^{g 2 = 2 * (n 0}} -n (L)) / (n 0 * L 2) ··· (2)
here,
L: distance in the radial direction from the optical axis n ₀ : refractive index on the optical axis n _(L) : refractive index at a position separated from the optical axis by a distance L in the radial direction.

According to the above equations (1) and (2), in order to adjust the conjugate length Tc, the length Z ₀ of the rod lens is changed, or the manufacturing parameters of the rod lens are changed to match the focusing parameter g. Can be considered. However, for this purpose, it is necessary to increase the number of processing steps for changing the cutting dimensions of the individual rod lenses, or to perform step management for frequently changing the manufacturing conditions of the rod lenses. For this reason, it is difficult to efficiently and stably continuously produce rod lenses having a uniform conjugate length Tc by such a manufacturing method.

  Therefore, an object of the present invention is to provide a method of manufacturing a plastic rod lens that can efficiently and stably manufacture a rod lens having a uniform conjugate length, and a method of supplying an uncured viscous material.

  In order to achieve the above object, the inventor of the present application has conducted various experiments and studies, and as a result, in the hopper of the kneading machine, the volatile component of the uncured viscous material is gradually reduced with time, particularly in the upper layer portion. For the first time, it was clarified that the composition of the uncured viscous material became non-uniform between the upper layer and the lower layer in the hopper. The present inventor has considered that the non-uniform composition of the uncured viscous material causes the refractive index distribution of the manufactured rod lens to fluctuate, which causes the conjugate length of the rod lens to fluctuate.

  Therefore, the method for producing a plastic rod lens of the present invention shows at least one kind of uncured viscous material of a plurality of kinds of uncured viscous materials having a predetermined viscosity, which shows different refractive indices after curing, in a hopper of a kneading machine. A stirring step of stirring at a predetermined stirring temperature, a kneading step of separately kneading a plurality of types of uncured viscous materials, and a kneading of each type of uncured viscous material, in which the refractive index after curing is outside the center. A spinning step of forming a filament by laminating concentrically so as to gradually lower toward the surface, a diffusion step of diffusing the components of the uncured viscous material between adjacent layers of the filament, and curing the filament. And a cutting step of cutting the hardened filamentous material.

  Thus, according to the present invention, the stirring step is provided before the kneading step. Thereby, even if the volatile component of the uncured viscous material volatilizes in the hopper, it is possible to suppress the composition from becoming non-uniform in the upper layer portion and the lower layer portion. Therefore, the composition of the uncured viscous material supplied to the kneader can be made uniform. As a result, variation in the refractive index distribution of the continuously produced rod lens array can be suppressed. Therefore, a rod lens having a uniform conjugate length can be efficiently and stably manufactured.

According to the present invention, preferably, in the stirring step, each of the plurality of types of uncured viscous materials is stirred in a hopper of a separate kneader.
As described above, by stirring the uncured viscous material for all the layers to be laminated in the spinning process, the composition of the uncured viscous material supplied to the kneader can be further uniformed.

According to the present invention, preferably, in the stirring step, the uncured viscous material laminated at least in the second layer from the center in the spinning step is stirred.
By stirring the uncured viscous material laminated on at least the second layer, it is possible to efficiently suppress the variation in the refractive index distribution of the rod lens array.

According to the present invention, preferably, the stirring temperature in the stirring step is in the range of 0C to 150C.
If the stirring temperature is too high, the components of the uncured viscous material evaporate or undergo thermal polymerization. On the other hand, if the stirring temperature is too low, the viscosity increases and stirring becomes difficult. Further, the stirring temperature is more preferably in the range of 50C to 100C.

According to the present invention, preferably, the predetermined viscosity in the stirring step is in the range of 10 ² to 10 ⁷ Pa · s (Pascal · second).
If the viscosity is too high, stirring becomes difficult. On the other hand, if the viscosity is too low, it is difficult to form a filament in the spinning process.

According to the present invention, preferably, in the stirring step, the uncured viscous material is stirred by rotating the stirring blade at a rotation speed in the range of 1 to 50 times per minute.
If the rotation speed of the stirring blade is too slow, it takes too much time for the composition of the uncured viscous material to be uniform, while if the stirring speed is too fast, depending on the viscosity of the uncured viscous material, Sufficient stirring becomes difficult due to rotation with the stirring blade. In addition, if the stirring speed is too high, the load on the motor that drives the stirring blades increases, and the motor capacity must be increased, resulting in an increase in cost.

According to the present invention, preferably, further, before the stirring step, a pre-stirring step of pre-stirring the uncured viscous material, a cooling step of cooling the pre-stirred uncured viscous material to a predetermined cooling temperature, Charging the uncured viscous material into a hopper of a kneading machine.
As described above, in the cooling step, if the pre-stirred uncured viscous material is cooled, volatilization of volatile components of the uncured viscous material can be suppressed.

  According to the present invention, preferably, the cooling temperature in the cooling step is a temperature in the range of 0C to 80C. Further, the range of 0 to 50 ° C. is more preferable.

According to the present invention, preferably, in the charging step, the cooled uncured viscous material is charged into the preliminary hopper a plurality of times, and is continuously supplied from the preliminary hopper to the hopper.
In this way, if the cooled uncured viscous material is charged in a plurality of times, the time during which the uncured viscous material stays in the preliminary hopper or hopper can be shortened. As a result, the amount of volatile components contained in the uncured viscous material can be reduced.

According to the present invention, preferably, the uncured viscous material contains, as components, a radical polymerizable vinyl monomer and a soluble polymer having good compatibility with a polymer formed from the radical polymerizable vinyl monomer. .
Thus, the viscosity of the uncured viscous material and the refractive index after curing can be easily adjusted.

According to the present invention, preferably, in the kneading step, the difference between the maximum value and the minimum value of the mass ratio of the composition of the radical polymerizable vinyl monomer and the soluble polymer of the uncured viscous material supplied to the kneader. Is within 2%.
If the variation is suppressed within 2% in this way, the variation of the conjugate length of the manufactured plastic rod lens can be suppressed within a range of, for example, ± 0.2 mm with respect to a predetermined conjugate length. By setting the variation of the conjugate length to ± 0.2 mm or less, high resolution can be substantially realized without adjusting the lens length and the like.

According to the present invention, preferably, the fluctuation range of the conjugate length of the continuously produced rod lens is within ± 0.2 mm.
As described above, if the variation width of the conjugate length is set to ± 0.2 mm or less, high resolution can be substantially realized without adjusting the lens length and the like.

  Further, the method of supplying the uncured viscous material of the present invention includes a stirring step of stirring a plurality of types of uncured viscous materials having a predetermined viscosity, which are to be materials of the plastic rod lens, in a hopper at a predetermined stirring temperature. And a kneading step of kneading the stirred uncured viscous material.

  Thus, according to the present invention, the stirring step is provided before the kneading step. Thereby, even if the volatile component of the uncured viscous material volatilizes in the hopper, it is possible to suppress the composition from becoming non-uniform in the upper layer portion and the lower layer portion. Therefore, the composition of the uncured viscous material supplied to the kneader can be made uniform.

  According to the present invention, a rod lens having a uniform conjugate length can be efficiently and stably manufactured.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
1. Manufacturing Steps After Kneading Step First, referring to FIG. 1, of the manufacturing steps of the plastic rod lens according to the present embodiment, steps after the kneading step will be described. FIG. 1 is a schematic view of a manufacturing process of a plastic rod lens in the present embodiment.

(1) Kneading Step In the kneading step, five types of uncured viscous materials having different refractive indices after curing are separately kneaded in five kneading units 1. Then, the five uncured viscous materials kneaded in each kneading unit 1 are sent to the spinning device 2.

  As shown in FIG. 1, the spinning apparatus 2 includes a spinning head 20, an interdiffusion unit 22, and a curing unit 23. In FIG. 1, the cross-diffusion part 22 and the hardening part 23 are schematically shown in cross section. An inert gas is introduced into the interdiffusion section 22 and the hardening section 23 in order to remove volatile substances released from the filament 3, and the inert gas is discharged together with the volatile substances.

(2) Spinning Step In the spinning step, the uncured viscous material is discharged from the composite spinning nozzle 21 in the spinning head 20 to generate the filament 3.

Here, FIG. 2A schematically shows a state where a filament is generated from the spinning nozzle 21.
As shown in FIG. 2 (A), the thread 3 has a quintuple concentric shape so that the refractive index n after curing gradually decreases from the center to the outside, such as n1>n2>...> N5. It is laminated and shaped.
It is preferable that the thickness of each layer of the filament 3 is set so as to satisfy the condition under which lens performance can be exhibited.

The viscosity of the uncured viscous material during shaping is preferably in the range of 10 ² to 10 ⁷ Pa · s. If the viscosity is too low, thread breakage is likely to occur during shaping, and it becomes difficult to form a thread. On the other hand, if the viscosity is too large, the operability at the time of shaping becomes poor, and concentric circles of the respective layers are impaired, or a thread having a large thickness unevenness is apt to be formed. The temperature at the time of shaping is preferably in the range of 0 ° C to 150 ° C.

  The filament discharged from the composite spinning nozzle is pulled up by the first nip roller 4 and sequentially passes through the mutual diffusion section 22 and the curing section 23 of the spinning device 2.

(3) Diffusion Step In the refractive index distribution of the filament immediately after being discharged from the composite spinning nozzle 21, as shown by the polygonal line I in FIG.
Therefore, in the diffusion step, while the filament 3 passes through the interdiffusion portion 22, the monomer component mainly of the uncured viscous material is mutually diffused between adjacent layers of the filament 3. As a result of the mutual diffusion, the refractive index distribution of the filament becomes a smooth and continuous distribution as shown by a curve II in FIG.
In this embodiment, the first ultraviolet irradiation device 24 irradiates the filament 3 passing through the mutual diffusion portion 22 with weak ultraviolet light.

(4) Curing Step Next, in the curing step, the designated filament is cured. In the present embodiment, the filament 3 passing through the curing processing section 23 is irradiated with strong ultraviolet rays from the surroundings by the second ultraviolet irradiation device 25 to photopolymerize and cure the filament 3.
As a light source of the second ultraviolet irradiation device 25, a carbon arc lamp, a high-pressure mercury lamp, a medium-pressure mercury lamp, a low-pressure mercury lamp, an ultra-high-pressure mercury lamp, a chemical lamp, a xenon lamp, a laser, or the like that generates light having a wavelength of 150 to 600 nm is used. Good.

In this embodiment, a photocuring catalyst is added to each uncured viscous material in order to perform photocuring treatment.
Note that a thermosetting catalyst may be added to the uncured viscous material, and the thread may be cured by heat treatment. In the heat treatment, for example, the filament is preferably heated for a predetermined time in a curing treatment unit such as a heating furnace controlled to a constant temperature.
Alternatively, both the light curing catalyst and the heat curing catalyst may be added to the uncured viscous material, and both the heat treatment and the light curing treatment may be performed to cure the thread.

  Further, the cured filamentous material may be subjected to a stretching treatment as necessary. The stretching process can be performed, for example, by controlling the peripheral speed ratio between the first nip roller 4 and the second nip roller 5 under an appropriate temperature condition between the first nip roller 4 and the second nip roller 5.

The stretching treatment may be performed continuously after the photocuring treatment, or may be performed after the cured thread is once wound around a winding section.
Moreover, you may perform a relaxation process as needed on the filamentous body which performed the drawing process. In the relaxation process, for example, under appropriate temperature conditions between the second nip roller 5 and the third nip roller, the peripheral speeds of the second nip roller 5 and the third nip roller are the same, or the peripheral speed of the third nip roller is slightly reduced. And set it up. The relaxation treatment may be performed continuously after the stretching treatment, or may be performed after the drawn filamentous material is once wound around the winding part.

(5) Cutting Step Next, in the cutting step, the cured filamentous material is cut into a predetermined length by a lens cutting machine.
In the present embodiment, the filaments that have passed through the second nip roller 5 are sequentially cut by the cutting machine 6, but the filaments may be once wound around the rollers, and then cut or stretched.
Further, after the rod lens array is formed from the cut rod lenses, both end surfaces of the rod lens may be mirror-polished.

2. Next, the components of the uncured viscous material will be described.
The uncured viscous material facilitates the adjustment of the viscosity during the formation of the filament and has a maximum refractive index at the center of the filament and a refractive index distribution that continuously decreases toward the outer periphery. It is preferred that the main composition be composed of a monomer and a soluble polymer soluble in the monomer.

  Examples of the radical polymerizable vinyl monomer include methyl methacrylate (n = 1.49), styrene (n = 1.59), chlorostyrene (n = 1.61), and vinyl acetate (n = 1.47). , 2,2,3,3-tetrafluoropropyl (meth) acrylate, 2,2,3,3,4,4,5,5-octafluoropentyl (meth) acrylate, 2,2,3,4,4 Fluorinated alkyl (meth) acrylates (n = 1.37 to 1.44) such as 1,4-hexafluorobutyl (meth) acrylate and 2,2,2-trifluoroethyl (meth) acrylate, refractive index 1.43 To 1.62 (meth) acrylates such as ethyl (meth) acrylate, phenyl (meth) acrylate, benzyl (meth) acrylate, alicyclic (meth) acrylate, hydroxyalkyl (meth) acrylate, alkylene glycol ( (T) acrylate, trimethylolpropane di or tri (meth) acrylate, pentaerythritol di, tri or tetra (meth) acrylate, diglycerin tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, etc. Also, diethylene glycol bisallyl carbonate, fluorinated alkylene glycol poly (meth) acrylate and the like can be mentioned.

  It is desirable that the soluble polymer has good compatibility with the polymer produced from the above-mentioned radical polymerizable vinyl monomer. Examples of such a soluble polymer include polymethyl methacrylate (n = 1.49), polymethyl methacrylate-based copolymer (n = 1.47 to 1.50), and poly-4-methylpentene-1 (n = 1). .46), ethylene / vinyl acetate copolymer (n = 1.46 to 1.50), polycarbonate (n = 1.50 to 1.57), polyvinylidene fluoride (n = 1.42), fluoride Vinylidene / tetrafluoroethylene copolymer (n = 1.42 to 1.46), vinylidene fluoride / tetrafluoroethylene / hexafluoropropene copolymer (n = 1.40 to 1.46), alkyl fluoride ( (Meth) acrylate polymers.

  Further, it is preferable to use a soluble polymer having the same refractive index for each layer, because the viscosity of the uncured viscous material is adjusted and a plastic rod lens having a continuous refractive index distribution from the center to the outside can be obtained. In particular, polymethyl methacrylate is excellent in transparency and has a high refractive index, so that it is suitable for use as a material for a refractive index distribution type plastic rod lens.

Further, it is preferable that a thermosetting catalyst or a photocuring catalyst is added to the uncured viscous material in order to cure the formed filamentous material.
Examples of the thermosetting catalyst include, for example, usually a peroxide-based catalyst or an azo-based catalyst.
Examples of light curing catalysts include, for example, benzophenone, benzoin alkyl ether, 4'-isopropyl-2-hydroxy-2-methylpropiophenone, 1-hydroxycyclohexylphenyl ketone, benzylmethyl ketal, 2,2-diethoxyacetophenone, chloro Thioxanthone, a thioxanthone-based compound, a benzophenone-based compound, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, N-methyldiethanolamine, triethylamine, and the like.
Note that both the thermosetting catalyst and the photocuring catalyst may be added to the uncured viscous material.

  Further, in the present invention, in order to remove the flare light and the crosstalk light and improve the lens performance, in the vicinity of the outer peripheral portion having an irregular refractive index distribution, at least a part of the visible light and near infrared light regions. A light-absorbing agent-containing layer containing a light absorbing agent that absorbs light in a wavelength range may be formed.

  As the light absorber, various dyes, pigments, and pigments capable of absorbing light having a wavelength used in an optical system using a rod lens can be used. These light absorbers are light absorbers that absorb only in a specific wavelength range, and two or more light absorbers having different absorption wavelengths may be used in combination. For example, when used as a lens array in a color scanner, a dye that absorbs light of each wavelength of RGB can be used in combination. Further, as the light absorbing agent in the present invention, those absorbing only a specific wavelength region among visible light (about 400 nm to 700 nm) and near infrared light (about 700 nm to 1000 nm) as described above may be used, Those that absorb the entire wavelength range may be used. In the case of forming a layer that absorbs all light in the visible light region, a black light absorber such as a mixture of a plurality of light absorbers and a black light absorber such as carbon black or graphite carbon can be used. .

  Further, the light absorbing agent is present almost uniformly in the light absorbing agent-containing layer, and is preferably present as uniformly as possible. At that time, it is preferable that the light absorber molecules are uniformly dispersed or bonded in the polymer constituting the light absorber containing layer. The content of the light absorbing agent in the light absorbing agent-containing layer is preferably 0.001 to 10% by mass, and more preferably 0.01 to 1% by mass.

3. Processing before Kneading Step Next, a step before kneading the uncured viscous material will be described.
In the present embodiment, in order to make the composition of the uncured viscous material supplied to the kneading machine uniform, before the kneading step, (1) a preliminary stirring step, (2) a cooling step, and (3) The charging step and (4) the stirring step are performed.

(1) Preliminary Stirring Step In this embodiment, the uncured viscous material is preliminarily stirred by a preliminary stirrer (not shown).
In the preliminary stirrer, the rotor is rotated to perform preliminary stirring. The rotation speed of the stirring blade may be a speed at which the composition of the uncured viscous material is sufficiently uniform, and is preferably in the range of 1 to 400 rotations / minute. The shape of the stirring blade may be any shape as long as the composition of the uncured viscous material such as a paddle blade can be sufficiently uniform.

  In this embodiment, the helical ribbon blade is used in consideration of the viscosity of the uncured viscous material. The stirring temperature of the uncured viscous material is preferably in the range of 0 ° C to 150 ° C, and more preferably in the range of 50 ° C to 100 ° C.

(2) Cooling Step After the preliminary stirring step, the uncured viscous material is cooled in order to prevent the monomer component of the uncured viscous material from volatilizing.
In the present embodiment, the uncured viscous material after the preliminary stirring is cooled at a temperature within the range of 0 to 80 ° C., and is stored under the cooling temperature until it is put into the kneading unit 1. The cooling temperature is more preferably in the range of 0 to 50C.

-About kneading unit Here, the schematic diagram of the kneading unit 1 is shown in FIG.
As shown in FIG. 1, the kneading unit 1 includes a kneader 10 for kneading the uncured viscous material, a hopper 11 for supplying the uncured viscous material to the kneader 10, and a preliminary hopper for supplying the uncured viscous material to the hopper. And a temperature controller 13 for controlling the temperature of the hopper 11.
In FIG. 1, the hopper 13 is shown in cross section.

The kneading unit 1 has a stirring blade 14 in the hopper 11 for stirring the uncured viscous material. The stirring blade 14 is connected to a motor 16 via a shaft 15 and rotates. Here, a helical ribbon blade is used as the stirring blade 14 in consideration of the viscosity of the uncured viscous material.
The shape of the stirring blade 14 may be any shape as long as the composition of the uncured viscous material can be sufficiently uniform.

(3) Inputting Step Subsequently, the cooled uncured viscous material is input into the hopper 11 of the kneader unit 1.
In the present embodiment, the uncured viscous material that has been cooled for 5 days is put into the preliminary hopper 12 five times every 24 hours.
The uncured viscous material charged into the preliminary hopper 12 continuously moves from the preliminary hopper 12 to the hopper 11 by its own weight.
Note that an inert gas or the like may be introduced into the preliminary hopper 12 and the uncured viscous material may be moved to the hopper 11 by the pressure.

(4) Stirring Step Next, the five uncured viscous materials are stirred in the hopper 11 of each kneading unit 1.
In the present embodiment, the uncured viscous material is supplied to the kneader 10 while being stirred by the stirring blade 14. The rotational speed of the stirring blade 14 may be a speed at which the composition of the pre-stirred uncured viscous material is sufficiently uniform. For example, it is preferable to stir within a range of 1 to 50 revolutions / minute. If the stirring speed is too slow, it takes time for the composition of the uncured viscous material to become uniform, and if the stirring speed is too fast, the uncured viscous material and the stirring blade rotate around depending on the viscosity of the uncured viscous material. This is because sufficient stirring becomes difficult. Further, if the stirring speed is too high, the load on the motor 16 for driving the stirring blade increases, and the motor capacity must be increased, which is not preferable from the viewpoint of cost.

  The shape of the stirring blade may be any shape as long as the composition of the uncured viscous material such as a paddle blade can be sufficiently uniform. In this embodiment, a helical ribbon blade is used in consideration of the viscosity of the uncured viscous material.

  The hopper 11 is maintained at a predetermined stirring temperature by the temperature controller 13. The stirring temperature is preferably in the range of 0 ° C to 150 ° C, and more preferably in the range of 50 ° C to 100 ° C. If the stirring temperature is too high, the components of the uncured viscous material evaporate or undergo thermal polymerization. On the other hand, if the stirring temperature is too low, the viscosity increases and stirring becomes difficult.

  As described above, before the kneading step, the step of stirring the uncured viscous material at a predetermined number of rotations to make the composition of the uncured viscous material uniform is provided, so that a change in the composition of the uncured viscous material can be suppressed. As a result, a rod lens having a conjugate length with a small variation width can be efficiently and stably manufactured in continuous production without adding a processing step such as a change in the rod lens length or a change in the radius ratio of each layer. .

  In addition, among the plurality of types of uncured viscous materials laminated in the spinning process, all types of uncured viscous materials may be stirred, or only some of them may be selectively agitated. May be. In addition, the preliminary stirring may be performed on each of the plurality of types of uncured viscous materials, may be selectively performed on the type of uncured viscous material to be stirred in the stirring process, or may be omitted. Good.

Hereinafter, the present invention will be specifically described with reference to examples.
In Example 1, the following composition was used as the uncured viscous material laminated on the first to fifth layers of the filament.

The composition of the uncured viscous material of the first layer was measured at 25 ° C. in polymethyl methacrylate (viscosity η = 0.40, MEK (methyl ethyl ketone). Hereinafter, polymethyl methacrylate in Examples and Comparative Examples was 47 parts by mass), 30 parts by mass of tricyclo [5.2.1.0 ^2,6 ] decanyl methacrylate, 23 parts by mass of methyl methacrylate, 0.25 parts by mass of 1-hydroxycyclohexyl phenyl ketone, and 0.1 of hydroquinone 0.1 Parts by weight.

The composition of the uncured viscous material of the second layer was as follows: 50 parts by mass of polymethyl methacrylate, 40 parts by mass of methyl methacrylate, 10 parts by mass of tricyclo [5.2.1.0 ^2,6 ] decanyl methacrylate, 1-hydroxycyclohexyl 0.25 parts by mass of phenyl ketone and 0.1 parts by mass of hydroquinone.

  The composition of the uncured viscous material of the third layer is polymethyl methacrylate 50 parts by mass, methyl methacrylate 40 parts by mass, 2,2,3,3,4,4,5,5-octafluoropentyl methacrylate 10 parts by mass, 0.25 parts by mass of 1-hydroxycyclohexyl phenyl ketone and 0.1 part by mass of hydroquinone.

  The composition of the uncured viscous material of the fourth layer is as follows: 50 parts by mass of polymethyl methacrylate, 40 parts by mass of methyl methacrylate, 10 parts by mass of 2,2,3,3,4,4,5,5-octafluoropentyl methacrylate, 0.25 parts by mass of 1-hydroxycyclohexyl phenyl ketone and 0.1 part by mass of hydroquinone.

The composition of the uncured viscous material of the fifth layer is 42 parts by mass of polymethyl methacrylate, 18 parts by mass of methyl methacrylate, 40 parts by mass of 2,2,3,3,4,4,5,5-octafluoropentyl methacrylate, 0.25 parts by mass of 1-hydroxycyclohexyl phenyl ketone and 0.1 part by mass of hydroquinone.
For the purpose of suppressing crosstalk light and flare light, the dye Blue ACR (manufactured by Nippon Kayaku Co., Ltd., maximum absorption) was added to each of the undiluted solutions for the fourth and fifth layers before heat kneading. 0.12% by mass of wavelength 576,616 nm), 0.10% by mass of dye MS Yellow HD-180 (manufactured by Mitsui Toatsu Dye Co., Ltd., maximum absorption wavelength 433 nm), dye MS Magenta HM-1450 (Mitsui Toatsu Dye ( Co., Ltd., maximum absorption wavelength: 520 nm) 0.08% by mass.

  Then, these uncured viscous materials were each preliminarily stirred at a temperature of 70 ° C., and then cooled to a temperature of 40 ° C. and stored.

  Next, the uncured viscous material was introduced into the preliminary hopper 12 of the kneading unit in an amount of 3 to 5 L (liter) every about 24 hours. The uncured viscous material charged into the preliminary hopper 12 was gradually moved by its own weight to the hopper 11 having a volume of 20 L. The temperature of the hopper 11 was maintained at a temperature of 50 ° C. by a temperature controller. Then, the uncured viscous material was sent to the spinning device 2 while stirring, and rod lenses were continuously produced for 5 days.

  In the spinning apparatus 2, five types of uncured viscous materials were simultaneously extruded from the composite spinning nozzle 21. In the present embodiment, the temperature of the composite spinning nozzle is set to 50 ° C., and the radius ratio of each layer is converted into the ratio of the thickness of each layer in the radial direction of the rod lens (the first layer is a radius). Layer / third / fourth / fifth layer = 18/50/29/2/1.

  Next, the filament 3 extruded from the composite spinning nozzle 21 is pulled up at a speed of 300 cm / min by the first nip roller 4 and passed through a 55 cm-long inter-diffusion processing section 22. The fibrous body 3 was passed through the center of a curing processing section (light irradiation section) 23 in which 18 chemical lamps of 60 cm and 20 W were stacked in two layers and arranged at equal intervals to be cured.

  The hardened filamentous material was taken up by a nip roller (300 cm / min), passed through a 30 cm long interdiffusion treatment section, and then 18 120 cm long, 40 W chemical lamps were arranged at regular intervals around the central axis. The center of the provided first curing processing unit (first light irradiation unit), and the second curing processing unit (second light irradiation unit) in which three 2KW high-pressure mercury lamps are arranged at equal intervals around the central axis. The thread was passed over and cured. The nitrogen flow rate in the interdiffusion processing section was 72 L / min. The radius of the obtained lens original yarn was 0.24 mm.

This lens fiber was stretched 2.2 times in an atmosphere of 135 ° C., and subjected to a relaxation treatment in an atmosphere of 150 ° C. so that the relaxation rate became 10/11.
The radius of the obtained rod lens was 0.17 mm, and the central refractive index was 1.497.

  In this way, the rod lens is produced continuously for 5 days, the variation of the composition of (1) the uncured viscous material in the hopper 11 is analyzed, and (2) the conjugate length and the rod lens of the manufactured rod lens are further analyzed. (3) MTF of the rod lens array constituted by the above was measured.

(1) Fluctuation of Composition In analyzing the composition of the uncured viscous material, 1 g of the uncured viscous material in the hopper was sampled every 8 hours for 5 days, and the composition was analyzed by a known gas chromatography method. Table 1 below shows the analysis results of the composition of the uncured viscous material laminated on the second layer of the filament.

However, in Table 1 above, “monomer 1” represents the mass ratio of the composition of methyl methacrylate, and “monomer 2” represents the mass of the composition of tricyclo [5.2.1.0 ^2,6 ] decanyl methacrylate. "Monomer 1" represents the total mass ratio of "monomer 1" and "monomer 2", and "polymer" represents the mass ratio of the composition of polymethyl methacrylate.

  As can be seen from Table 1 above, during continuous production for 5 days, the variation as the difference between the maximum value and the minimum value of the composition of each component is within 2%. In addition, for example, the fluctuation range of the conjugate length within an arbitrary 24 hours of 5 days is within 2%. Accordingly, it can be seen that the composition of the uncured viscous material was made uniform by stirring.

-Preparation of rod lens array Next, in this example, a rod lens array was prepared using the cut rod lenses.
In preparing a rod lens array, a plurality of rod lenses are arranged in a line between phenolic resin substrates (thickness: 1 mm), and an adhesive (a carbon black containing 0.5% by mass of carbon black) is provided in a gap. An adhesive was filled with a black-added Somar Epiform (trade name), and the adhesive was cured. Next, both end surfaces of the rod lens were mirror-polished perpendicularly to the optical axis to form a rod lens array having a lens length of 4.4 mm.

(2) Conjugation length Further, the conjugate length of the manufactured rod lens was measured. For the conjugate length, the conjugate length was changed at the time of MTF measurement described later, a conjugate length at which the MTF had a maximum value was found, and the value was used as the conjugate length of the rod lens.

  The measurement result of the conjugate length is shown in the graph of FIG. The horizontal axis of the graph represents the elapsed time from the start of continuous production, and the vertical axis represents the conjugate length. The broken line III in the graph connects the plots of the measured values. As shown by the polygonal line III, the fluctuation range of the conjugate length Tc of the rod lens continuously produced for five days is within ± 0.2 mm with respect to the predetermined conjugate length of 10.0 mm. Further, for example, the fluctuation width of the conjugation length within an arbitrary 24 hours of 5 days is within ± 0.2 mm. Therefore, it can be seen that a rod lens having a stable conjugate length could be manufactured.

(3) MTF
Then, the MTF indicating the resolution of the rod lens array was measured.
FIG. 5 shows an MTF measuring device. This measuring device includes a light source 71, a wavelength filter 72, a diffusion plate 73, a grating (test chart) 74, and a CCD line sensor 75 which are sequentially arranged. The grating 74 and the CCD line sensor 75 are separated by a predetermined conjugate length of the rod lens.
In the present embodiment, a grating 74 having a spatial frequency of 12 (line pair (Lp) / mm) is used. The spatial frequency indicates the number of lines in a width of 1 mm, with a combination of a transparent line and a light-shielded (black) line as one line.

In the measurement, a single lens or a rod lens array 70 is provided between the grating 74 and the CCD line sensor 75.
Then, the light amount of the image of the grating 74 is measured by the CCD line sensor 75 installed on the image forming surface, and the maximum value (iMAX) and the minimum value (iMIN) of the measured light amount as shown in FIG. , MTF were determined by the following equation (3).

  MTF (%) = ((iMAX−iMIN) / (iMAX + iMIN)) × 100 (3)

  The graph of FIG. 6A shows the result of MTF measured at 525 nm and 12 Lp / mm at a predetermined conjugate length (10.0 mm) of a lens array manufactured at a predetermined lens length (4.4 mm). The horizontal axis of the graph represents the elapsed time from the start of continuous production, and the vertical axis represents the MTF. A polygonal line V in the graph is obtained by connecting plots of measured values. As shown by the polygonal line V, the MTF of the rod lens produced continuously for 5 days was in the range of 68% to 73%, the fluctuation range of the MTF was very small at 5%, and the lens performance was very stable. In addition, none of the MTF was less than 60%, and the lens performance was good.

Next, a second embodiment will be described.
In Example 2, the same five uncured viscous materials as those used in Example 1 were used, and only the uncured viscous material laminated on the second layer of the filament having the largest radius ratio was placed in the hopper. A rod lens was manufactured in exactly the same manner as in Example 1 except that the other types of uncured viscous materials were not stirred in the hopper.

  In the second embodiment, the fluctuation of the composition of (1) the uncured viscous material in the hopper 11 is analyzed in the same manner as in the above-described embodiment. (3) MTF of the rod lens array composed of lenses was measured.

(1) Fluctuation of composition of uncured viscous material First, Table 2 below shows an analysis result of fluctuation of the composition of the uncured viscous material in the hopper laminated on the second layer of the filament. In addition, Table 3 shows the results of analysis of the variation in the composition of the uncured viscous material in the unstirred hopper laminated on the third layer of the filament.

  As shown in Table 2 above, in the uncured viscous material stirred in the hopper, for example, the fluctuation amount of the monomer 2 is as small as 0.3%, and the composition of the uncured viscous material is made uniform. You can see that. On the other hand, as shown in Table 3 above, in the uncured viscous material that is not stirred in the hopper, for example, the fluctuation amount is large at 4.3% for the material-2, and the composition of the uncured viscous material is large. Is not sufficiently uniform.

(2) Conjugate length The conjugate length of the rod lens manufactured in Example 2 was measured.
The measurement result of the conjugate length is shown in the graph of FIG. The broken line VII in the graph connects the plots of the measured values. As shown by the polygonal line VII, the fluctuation range of the conjugate length Tc of the rod lens continuously produced for five days was 0.6 mm from 9.7 mm to 10.3 mm.

(3) MTF
Further, the MTF of the rod lens array constituted by the rod lenses manufactured in Example 2 was measured.
The measurement results are shown in the graph of FIG. The line VIII in the graph connects the plots of the measured values. As shown by the polygonal line VIII, the MTF of the rod lens manufactured continuously for 5 days was in the range of 65% to 73%, the fluctuation range of the MTF was small, and the lens performance was stable. In addition, none of the MTF was less than 60%, and the lens performance was generally good.

  Thus, even when the uncured viscous material laminated on any one of the layers is agitated in the hopper, the plastic rod lens having a predetermined conjugate length, although having a slight amplitude as compared with Example 1, can be used. It can be manufactured efficiently and stably.

(Comparative example)
Next, a comparative example will be described.
In the comparative example, the same five kinds of uncured viscous materials as used in the example were used, and a rod lens was manufactured in exactly the same manner as in the example except that the uncured viscous material was not stirred in the hopper. did.

  In the comparative example, the composition of (1) the uncured viscous material in the hopper 11 was analyzed in the same manner as in the above example, and (2) the conjugate length and rod lens of the manufactured rod lens were analyzed. (3) MTF of the rod lens array constituted by the above was measured.

(1) Fluctuation of composition of uncured viscous material First, Table 4 below shows an analysis result of fluctuation of composition of uncured viscous material in the hopper.

  As shown in Table 4 above, in the comparative example, the fluctuation amount was as large as 4.6% for the monomer 2, and it can be seen that the composition of the uncured viscous material was not sufficiently uniform.

(2) Conjugate length The conjugate length of the rod lens manufactured in the comparative example was measured.
The measurement result of the conjugate length is shown in the graph of FIG. The broken line IV in the graph connects the plots of the measured values. As shown by the polygonal line IV, the fluctuation range of the conjugate length Tc of the rod lens manufactured continuously for 5 days is as large as 0.9 mm between 9.5 mm and 10.4 mm, and there is a large variation in the conjugate length. I understand.

(3) MTF
Further, the MTF of the rod lens array composed of the rod lenses manufactured in the comparative example was measured.
The measurement results are shown in the graph of FIG. A broken line VI in the graph connects the plots of the measured values. As shown by the polygonal line VI, the MTF of the rod lens continuously manufactured for 5 days was in the range of 52% to 73%, the fluctuation range of the MTF was as large as 21%, and the lens performance fluctuated greatly. Further, those having an MTF of less than 60% accounted for 10% or more of the whole, and many had insufficient lens performance.

  Thus, when the stirring step is omitted, it is difficult to efficiently and stably produce a plastic rod lens having a predetermined conjugate length.

In each of the embodiments described above, examples in which the present invention is configured under specific conditions have been described. However, the present invention can be variously changed and combined, and the present invention is not limited to this.
For example, in the above-described embodiment, an example in which a five-layered fibrous body is generated has been described. However, in the present invention, the number of layers of the fibrous body is not limited to five, and may be any suitable number of laminations. it can. However, in order to make the refractive index distribution of the rod lens close to the ideal distribution, it is desirable that the thread-like body has a range of, for example, 4 to 7 layers.

It is a schematic diagram of a plastic rod lens manufacturing process. (A) is a schematic cross-sectional view showing a configuration of a composite spinning nozzle used in a spinning step in a method of manufacturing a plastic rod lens, and (B) schematically shows a refractive index distribution of a filament before a diffusion step. It is a graph and (C) is a graph which shows typically the refractive index distribution of the filamentous body after a diffusion process. It is a schematic diagram of a kneading unit of the present invention. (A) is a graph showing the change in the conjugate length of the plastic rod lens manufactured in Example 1, and (B) is a graph showing the change in the conjugate length of the plastic rod lens manufactured in the comparative example. (A) is a schematic configuration diagram of a measuring device of a resolution (MTF) of a rod lens array, and (B) is a graph showing a measurement result of a bridge in a lattice image. (A) is a graph showing a change in MTF of a plastic rod lens array manufactured in Example 1, and (B) is a graph showing a change in MTF of a plastic rod lens array manufactured in a comparative example. 10 is a graph showing a change in conjugate length of a plastic rod lens manufactured in Example 2. 9 is a graph showing a change in MTF of a plastic rod lens array manufactured in Example 2.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 Kneading unit 2 Spinning device 3 Filament 4 First nip roller 5 Second nip roller 6 Lens cutter 10 Kneader 11 Hopper 12 Preliminary hopper 13 Temperature controller 14 Rotor blade 15 Shaft 16 Motor 20 Spinning head 21 Composite spinning nozzle 22 Mutual diffusion Unit 23 Curing unit 24 First ultraviolet irradiation device 25 Second ultraviolet irradiation device 70 Rod lens array 71 Light source 72 Filter 73 Diffusion plate 74 Lattice 75 CCD line sensor

Claims (13)

After curing, showing different refractive indices, at least one type of uncured viscous material of a plurality of types of uncured viscous materials having a predetermined viscosity, in a hopper of a kneader, a stirring step of stirring at a predetermined stirring temperature,
A kneading step of kneading a plurality of types of uncured viscous materials separately,
A spinning step of kneading each kind of uncured viscous material, concentrically laminating so that the refractive index after curing gradually decreases from the center toward the outside, and forming a filament.
A diffusion step of diffusing components of the uncured viscous material between adjacent layers of the filamentous body;
A curing step of curing the filamentous body,
A cutting step of cutting the cured filament,
A method for producing a plastic rod lens, comprising:   2. The method of manufacturing a plastic rod lens according to claim 1, wherein, in the stirring step, each of the plurality of types of uncured viscous materials is stirred in a hopper of a separate kneader.   The method of manufacturing a plastic rod lens according to claim 1, wherein in the stirring step, the uncured viscous material laminated at least as a second layer from the center in the spinning step is stirred.   The method for producing a plastic rod lens according to any one of claims 1 to 3, wherein the stirring temperature in the stirring step is in a range of 0 to 150 ° C. The method for producing a plastic rod lens according to any one of claims 1 to 4, wherein the predetermined viscosity in the stirring step is in a range of 10 ² to 10 ⁷ Pa · s.   The plastic rod lens according to any one of claims 1 to 5, wherein, in the stirring step, the uncured viscous material is stirred by rotating a stirring blade at a rotation speed within a range of 1 to 50 times per minute. Manufacturing method. Further, before the stirring step,
A pre-stirring step of pre-stirring the uncured viscous material,
A cooling step of cooling the pre-stirred uncured viscous material to a predetermined cooling temperature,
A charging step of charging the cooled uncured viscous material into a hopper of the kneading machine,
The method for manufacturing a plastic rod lens according to any one of claims 1 to 6, comprising:   The method for manufacturing a plastic rod lens according to claim 7, wherein the cooling temperature in the cooling step is a temperature within a range of 0 to 80C.   9. The method of manufacturing a plastic rod lens according to claim 7, wherein in the charging step, the cooled uncured viscous material is charged into the preliminary hopper a plurality of times and continuously supplied from the preliminary hopper to the hopper.   10. The method according to claim 1, wherein the uncured viscous material includes a radical polymerizable vinyl monomer and a soluble polymer having good compatibility with a polymer formed from the radical polymerizable vinyl monomer as components. The method for producing a plastic rod lens according to claim 1. In the kneading step, in the composition ratio of the radically polymerizable vinyl monomer and the soluble polymer of the uncured viscous material supplied to the kneader, a fluctuation as a difference between a maximum value and a minimum value of each mass ratio. The method for producing a plastic rod lens according to claim 10, wherein the amount is within 2%. The method of manufacturing a plastic rod lens according to any one of claims 1 to 11, wherein a fluctuation width of a conjugate length of the continuously produced rod lens is within ± 0.2 mm. A stirring step of stirring a plurality of types of uncured viscous materials having a predetermined viscosity as a material of the plastic rod lens in a hopper at a predetermined stirring temperature,
A kneading step of kneading the stirred uncured viscous material,
A method for supplying an uncured viscous material, comprising:

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