JP2002243911A - Rod lens, rod lens array, led printer and scanner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rod lens and a lens array improved in electrifying performance without spoiling lens characteristics, and an LED printer and a scanner having excellent image characteristics and maintainability. SOLUTION: This rod lens has a refractive index distribution where a refractive index is continuously decreased from the center to the outer peripheral part, and is constituted to incorporate an electrification preventing agent inside.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rod lens and a rod lens array that can be used as various light transmission paths, and an LED printer and a scanner using the same.

[0002]

2. Description of the Related Art As a rod lens having a continuous refractive index distribution inside, a glass lens has already been proposed in Japanese Patent Publication No. 47-816. Plastics are proposed in Japanese Patent Publication No. 47-28059.

Generally, a rod lens has both end faces
The mirror surface is polished so as to be a parallel plane perpendicular to the central axis, and is used alone as a micro lens. Further, many of them are closely arranged and bonded and integrated, and are widely used in the form of a lens array as line sensor components for copying machines, facsimile machines, scanners, etc., and also for writing devices of LED printers.

[0004]

In an LED printer or scanner using a plastic rod lens, toner or dust easily adheres to the lens end surface during manufacturing or during long-term use due to the chargeability of the lens material. Therefore, a problem that image characteristics are degraded in high-resolution printing or reading is likely to occur. Further, it is necessary to wipe off toner particles, dust, and the like attached to the lens end face. In particular, when toner particles are attached to an LED printer, it is necessary to wipe off the lens surface with a solvent or the like, and maintenance is troublesome.

[0005] In order to improve the chargeability of a plastic rod lens, there is a method in which a hydrophilic coating is applied to the lens surface. However, problems such as unevenness in the thickness of the coating film and lens characteristics due to uniformity tend to occur. Practical use is difficult in applications requiring high resolution.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a rod lens and a lens array having improved chargeability without impairing the lens characteristics, and an LED printer and a scanner excellent in image characteristics and maintenance.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a rod lens having a refractive index distribution in which the refractive index decreases continuously from the center toward the outer peripheral portion and containing an antistatic agent.

The present invention also relates to a rod lens array having the above-mentioned rod lenses arranged.

The present invention also relates to an LED printer provided with the above-mentioned rod lens array.

The present invention further relates to a scanner provided with the above-mentioned rod lens array.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail.

FIG. 1 is a perspective view of a gradient index lens which is an example of the rod lens of the present invention. Assuming that the refractive index on the central axis 2 is N ₀ and the refractive index distribution constant is A, the lens 1 has a refractive index N at a distance r from the central axis in a radial direction (in a cross section perpendicular to the central axis). (R) is a transparent cylinder having a refractive index distribution substantially represented by the following equation.

N (r) = N ₀ (1-Ar ² ) (1) The rod lens of the present invention is preferably made of plastic, and contains an antistatic agent inside.

The antistatic agent in the present invention may be present uniformly or partially in the entire rod lens, but may be present partially. It is preferable that an antistatic agent is present in a region containing In order to enhance the antistatic effect of the entire rod lens, it is preferable that the antistatic agent is dispersed throughout the rod lens, but the rod lens is easily manufactured and the amount of the antistatic agent used is reduced. In order to achieve this, it is preferable that the antistatic agent is partially present.

At this time, when the main purpose is to improve the charging property of the side surface (curved surface of the outer periphery) of the rod lens, for example, when the purpose is to improve the arrangement accuracy of the lenses at the time of manufacturing a rod lens array as described below, Assuming that the radius of the rod lens is R, it is preferable that an antistatic agent is contained in a predetermined region of the outer periphery of the rod lens, particularly, a region where the distance r from the center axis of the rod lens is 0.6R or more. Is preferably a region including the outermost peripheral portion (side surface) of the rod lens.

When the main purpose is to improve the chargeability of the end surface (circular flat surface) of the rod lens, particularly when the rod lens is used for an LED printer application in which adhesion of toner particles and dust to the end surface is a problem, the rod In order to prevent toner particles and dust from adhering to the center of the end surface where the amount of emitted light is particularly large at the lens end surface, it is preferable to include an antistatic agent in a cylindrical region around the center axis of the rod lens. It is preferable that the antistatic agent is contained in a predetermined region including a region where the distance r from the central axis is 0.3R or less. It is more preferable to include an antistatic agent in a predetermined region including a region having a distance r from the central axis of 0.5R or less,
It is particularly preferable to include an antistatic agent in a predetermined region including a region where the distance r from the central axis is 0.7R or less.

Examples of the antistatic agent in the present invention include polyoxyethylene alkylamine, polyoxyethylene olein ether, polyglycerin fatty acid ester, potassium polyoxyethylene alkyl ether phosphate, polyoxyethylene phenyl ether phosphate, stearyltrimethylammonium chloride. , Mono or dialkyl ammonium chloride, stearyl betaine, alkylamine oxide, polyoxyethylene nonylpropenyl phenyl ether, polyoxyethylene nonyl propenyl phenyl ether sulfate ammonium chloride and the like.

In the present invention, the content of the antistatic agent contained in the plastic rod lens is determined based on 100 parts by mass of the plastic material in the antistatic agent-containing region in order to obtain a sufficient antistatic effect. 0.01 parts by mass or more is preferable. Further, if the content is too large, the transparency is lowered due to phase separation.
It is preferably at most 20 parts by mass, more preferably at most 2 parts by mass with respect to parts by mass.

The rod lens of the present invention having the above-described structure can suppress the adhesion of charged particles such as dust and toner to the surface of the rod lens by the antistatic agent contained therein. Since the polymethyl methacrylate-based polymer is excellent in transparency and mechanical strength while having a high chargeability, the rod lens of the present invention has a polymethyl methacrylate-based polymer in at least a part of the region. In particular, when the polymethyl methacrylate-based polymer is contained in the entire rod lens, it has a particularly large antistatic effect.

In the rod lens of the present invention, a plurality of the rod lenses are arranged in parallel between the substrates, fixed by bonding, cut on a surface perpendicular to the axial direction of the rod lens, and mirror-finished on the end surface to obtain a predetermined rod lens. By setting the length of the lens, a rod lens array can be obtained.

Since the rod lens of the present invention contains an antistatic agent therein, it is difficult for charged particles such as dust to adhere to the rod lens array when the rod lens array is manufactured, and the arrangement disorder due to the adhesion of the charged particles to the rod lens is reduced. Therefore, a rod lens array with high alignment accuracy can be obtained. For this reason, the rod lens array of the present invention has small performance unevenness and can be used for applications such as scanners and printers having a high resolution of, for example, 600 dpi or more.

The rod lens array of the present invention has a high resolution of, for example, 600 dpi or more when used in an image sensor such as a scanner since charged particles such as dust and dirt do not adhere to the end surface of the mirror-finished rod lens. Reading can be performed stably.

Further, the rod lens array of the present invention is
When used in the optical system of a D printer, the frequency of occurrence of troubles due to toner adherence to the end surface of the rod lens is greatly reduced.

In the present invention, a plastic rod lens can be manufactured as follows. An antistatic agent is mixed into one or more uncured materials among the N uncured materials having a refractive index n1>n2>...> NN (N ≧ 3) of the cured material. In such an arrangement, the refractive index of these uncured materials gradually decreases from the center toward the outer peripheral surface,
Further, it is shaped into an uncured laminate (hereinafter, appropriately referred to as a "filament") in which a plurality of layers are concentrically laminated, and the refractive index distribution between the respective layers of the filament becomes a continuous distribution. It is manufactured by performing a hardening treatment on the filament while performing the interdiffusion treatment of the substance or after performing the interdiffusion treatment.
In order to make the refractive index distribution of the obtained rod lens close to the ideal distribution, N is desirably in the range of 4 to 6.

The thickness of each layer of the uncured laminate at the time of manufacturing the rod lens in the present invention is set to a condition that allows the lens performance to be exhibited. The antistatic effect of the lens can be achieved by introducing the antistatic agent into the uncured material of all the layers or any of the layers and allowing the antistatic agent to be present in the lens.

The uncured material has a viscosity at the time of shaping of 10 ² to 1
It is preferably a curable material at 0 ⁷ Pa · s. If the viscosity is too low, thread breakage will occur during shaping, making it difficult to form a thread. On the other hand, if the viscosity is too high, the operability during shaping is poor, and concentricity of each layer is impaired, or a thread having a large thickness unevenness is apt to be formed, which is not preferable. The shaping is preferably performed at a temperature of 0 ° C to 150 ° C.

The substance constituting the uncured product includes a radically polymerizable vinyl monomer, or a radically polymerizable vinyl monomer and a polymer soluble in the monomer (hereinafter referred to as "soluble polymer" as appropriate). And the like.

Specific examples of the radical polymerizable vinyl monomer include methyl methacrylate (n = 1.49), styrene (n = 1.59), and chlorostyrene (n = 1.6).
1), 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,
3,4,4,4-hexafluorobutyl (meth) acrylate,
Fluorinated alkyl (meth) acrylates such as 2,2,2-trifluoroethyl (meth) acrylate (n = 1.37 to
1.44), (meth) acrylates having a refractive index of 1.43 to 1.62 such as ethyl (meth) acrylate, phenyl (meth) acrylate, benzyl (meth) acrylate, alicyclic (meth) acrylate, and hydroxyalkyl ( (Meth) acrylate, 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 Other examples include diethylene glycol bisallyl carbonate, fluorinated alkylene glycol poly (meth) acrylate, and the like.

In order to facilitate the adjustment of the viscosity of the uncured material when forming the filament from the uncured material, and to have a continuous refractive index distribution from the center to the outer periphery of the filament, The uncured product is preferably composed of a radical polymerizable vinyl monomer and a soluble polymer.

The soluble polymers that can be used here include:
A polymer having good compatibility with the polymer produced from the radical polymerizable vinyl monomer is used. For example, polymethyl methacrylate (n = 1.49), polymethyl methacrylate copolymer (n = 1.47 to 1) .50), 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), vinylidene fluoride / tetrafluoroethylene copolymer (n = 1.42 to 1.46),
Vinylidene fluoride / tetrafluoroethylene / hexafluoropropene copolymer (n = 1.40 to 1.46),
An alkyl fluoride (meth) acrylate-based polymer is exemplified.

In order to adjust the viscosity of the uncured material, when a soluble polymer having the same refractive index is used for each layer,
This is preferable because a plastic rod lens having a continuous refractive index distribution from the center to the outer periphery can be easily obtained. In particular, since polymethyl methacrylate has excellent transparency and a high refractive index itself, it is suitable as a soluble polymer used for forming the gradient index rod lens of the present invention.

In order to cure the thread formed from the uncured material, it is preferable to add a thermosetting catalyst or a photocuring catalyst to the uncured material. As a thermosetting catalyst,
Usually, a peroxide-based or azo-based catalyst is used. As the photo-curing catalyst, benzophenone, benzoin alkyl ether, 4'-isopropyl-2-hydroxy-2-
Methyl propiophenone, 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.

In order to cure the uncured material, the filament containing the thermosetting catalyst and / or the photocuring catalyst is subjected to a heat treatment or a photocuring treatment. When the uncured material contains both a thermosetting catalyst and a photocuring catalyst, both heat treatment and photocuring treatment can be performed. As the curing treatment, it is preferable that the uncured material containing the photocuring catalyst is irradiated with ultraviolet rays from the surroundings.

The rod lens of the present invention can be manufactured by using, for example, a thread forming apparatus shown in FIG. FIG.
FIG. 1 is a schematic schematic configuration diagram of a filament forming apparatus, and shows a cross-sectional view of a mutual diffusion unit 12 and a curing processing unit 13.
In the figure, reference numeral 10 is a concentric composite spinning nozzle, 11 is an extruded uncured filament, 12 is an interdiffusion unit for diffusing monomers of each layer of the filament mutually to give a refractive index distribution, 13 is a curing processing unit for curing the uncured material,
14 is a take-off roller, 15 is a manufactured rod lens, 16 is a winding section, 17 is an inert gas inlet, 18
Is an inert gas outlet.

The filament 11 discharged from the composite spinning nozzle 10 is taken up by a take-up roller 14, passes through a mutual diffusion section 12 and a curing section 13, and is finally taken up by a take-up section 16. At this time, an inert gas such as a nitrogen gas is introduced from the inert gas inlet 17 to remove volatile substances released from the filament 11 from the interdiffusion section 12 and the curing section 13. Volatile substances are discharged from the inert gas outlet 18.

The cured filamentous material may be subjected to a stretching treatment if necessary. The stretching process can be performed, for example, by controlling the peripheral speed ratio between the take-up roller 14 and the take-up unit 16 between the take-up roller 14 and the take-up unit 16 under appropriate temperature conditions. Also, after being wound once on the winding section, a stretching process may be performed,
Further, a relaxation process may be performed.

When a photocuring catalyst is contained in the uncured material, the light source used for photopolymerization in the photocuring treatment of the uncured material is a carbon arc lamp or a high-pressure mercury lamp that generates light having a wavelength of 150 to 600 nm. , Medium pressure mercury lamp, low pressure mercury lamp,
An ultra-high pressure mercury lamp, a chemical lamp, a xenon lamp, a laser beam and the like can be mentioned.

When a thermosetting catalyst is contained in the uncured product, the thermosetting process of the uncured product is performed by performing heat treatment for a predetermined time in a curing process section such as a heating furnace controlled at a constant temperature. be able to.

The rod lens thus obtained is
It is cut to a predetermined length, and a rod lens array having the following structure can be manufactured.

FIG. 3 is a perspective view of one embodiment of the rod lens array of the present invention. The rod lens array of the present embodiment has a structure in which a plurality of cylindrical rod lenses 19 are arranged in parallel between two substrates 20. The arrangement of the rod-shaped rod lenses may be a single layer arranged in one stage,
As shown in FIG. 3, two layers may be stacked in two layers, or three or more layers (three layers) may be stacked. It is preferable that adjacent rod lenses are arranged in parallel so that they are in contact with each other, and when two or more layers are stacked and stacked, they should be stacked in a bale stack so that the gap between the rod lenses is minimized. Is preferred.

The LED printer and scanner of the present invention
It is configured using the rod lens array as described above.
Therefore, printing spots and spots on a read image due to adhesion of dust, dust, toner, and the like are suppressed, and the image has excellent image characteristics.

The structure of the LED printer can be a publicly known one. Usually, an LED head including an LED light emitting element array, a rod lens array and a photosensitive drum, and a toner based on light information detected on the photosensitive drum are used. And a printing unit for transferring the image to paper.

The structure of the scanner may be a known one, and is assembled by sequentially arranging a light source, a rod lens array, and a light receiving sensor. The scanner of the present invention can be used for both monochrome and color scanners. As a light source, an LED light source of RGB three primary colors or a white light source is used. In addition, the light receiving sensor is LE of RGB three primary colors.
When using the D light source, any of a monochrome sensor and a light receiving sensor for primary colors can be used. When a white light source is used, a light receiving sensor for three primary colors can be used.

[0044]

The present invention will be described in detail with reference to the following examples.

In the examples and comparative examples, the refractive index distribution and the lens performance (MTF) were measured by the following methods.

(Measurement of Refractive Index Distribution) The refractive index distribution was measured by a known method using an Interfaco interference microscope manufactured by Carl Zeiss.

(Measurement of Lens Performance (MTF)) The MTF indicating the resolution of the rod lens is represented by the light source 21 and the filter 2.
2, diffusion plate 23, spatial frequency 12 (line pair (Lp)
/ Mm), a single lens or rod lens array 25 polished on both end surfaces perpendicular to the optical axis, and a CCD
Using a device in which the line sensors 26 are arranged in this order as shown in FIG. 4, a grid image (FIG. 5) is read by a CCD line sensor installed on the image plane, and the maximum value (iMAX) of the measured light amount is obtained. Measure the minimum value (iMIN),
It was determined by the following equation.

MTF (%) = ((iMAX−iMIN) / (iMAX
+ IMIN)) × 100 Here, as shown in the grid of FIG. 4, the spatial frequency is a combination of a transparent line and a light-shielded (black) line as one line, and how many combinations of this line are provided within a width of 1 mm. It shows whether it is.

(Example 1) Polymethyl methacrylate ([η] = 0.40, measured in MEK at 25 ° C., the same polymethyl methacrylate was used in the following Examples and Comparative Examples) 50 Parts by mass, benzyl methacrylate 36 parts by mass, methyl methacrylate 14
Parts by mass, 0.25 parts by mass of 1-hydroxycyclohexyl phenyl ketone, 0.2 polyoxyethylene alkylamine (surfactant "Amate 320" manufactured by Kao Corporation) 0.2
Parts by mass and 0.1 parts by mass of hydroquinone were heated and kneaded at 70 ° C. to prepare a first layer forming stock solution.

51 parts by mass of polymethyl methacrylate, 49 parts by mass of methyl methacrylate, 0.25 parts by mass of 1-hydroxycyclohexyl phenyl ketone, 0.2 of polyoxyethylene alkylamine (surfactant "Amate 320" manufactured by Kao Corporation) 0.2 Parts by mass and hydroquinone 0.1
The mass part was heated and kneaded at 70 ° C. to prepare a stock solution for forming a second layer.

48 parts by weight of polymethyl methacrylate, 37 parts by weight of methyl methacrylate, 15 parts by weight of 2,2,3,3,4,4,5,5-octafluoropentyl methacrylate, 0.25 part by weight of 1-hydroxycyclohexyl phenyl ketone Parts, 0.2 parts by mass of polyoxyethylene alkylamine (surfactant “Amate 320” manufactured by Kao Corporation) and 0.1 parts by mass of hydroquinone were heated and kneaded at 70 ° C. to obtain a stock solution for forming a third layer.

45 parts by weight of polymethyl methacrylate, 25 parts by weight of methyl methacrylate, 30 parts by weight of 2,2,3,3,4,4,5,5-octafluoropentyl methacrylate, 0.25 part by weight of 1-hydroxycyclohexylphenyl ketone Parts, 0.2 parts by mass of polyoxyethylene alkylamine (surfactant "Amate 320" manufactured by Kao Corporation) and 0.1 parts by mass of hydroquinone, infrared absorption dye "CY-10" 0 manufactured by Nippon Kayaku Co., Ltd. 0.015 parts by mass was heated and kneaded at 70 ° C. to prepare a stock solution for forming a fourth layer.

42 parts by weight of polymethyl methacrylate, 15 parts by weight of methyl methacrylate, 43 parts by weight of 2,2,3,3,4,4,5,5-octafluoropentyl methacrylate, 0.25 part by weight of 1-hydroxycyclohexylphenyl ketone Parts, 0.2 parts by mass of polyoxyethylene alkylamine (Surfactant “Amate 320” manufactured by Kao Corporation) and 0.1 parts by mass of hydroquinone were heated and kneaded at 70 ° C. to prepare a fifth layer forming stock solution.

The five kinds of stock solutions were sequentially arranged from the center so that the refractive index after curing became lower, and were simultaneously extruded from a concentric five-layer composite spinning nozzle. The temperature of the composite spinning nozzle is 50 ° C., and the discharge ratio of each layer is the ratio of the thickness (first layer is radius) of each layer in the radial direction of the rod lens, the first layer / second layer / third layer. / 4th layer / 5th layer = 35/38/20
/ 6/1.

Next, the filament extruded from the composite spinning nozzle was taken up by a nip roller (120 cm /
Minute), passing through a 55 cm long interdiffusion treatment part, and then above the center of a curing treatment part (light irradiation part) in which twelve 120 cm long, 40 W chemical lamps are arranged at equal intervals around the central axis. The mixture was hardened by passing through a fibrous body and wound around a winding section.

The radius (r) of the obtained rod lens is 0.5.
The refractive index was 1.512 at the center and 1.468 at the outer periphery.

The 245 rod lenses were arranged in a row between phenolic resin substrates (thickness: 1 mm), and an adhesive (carbon black was added so as to contain 0.5% by mass of carbon black) in the gap. Epiform (product name,
Somar))) and the adhesive was cured. Thereafter, both ends are cut and polished, and the lens length is 6.8 mm.
Was manufactured.

12 Lp / m of this rod lens array
When the characteristics at m and a wavelength of 740 nm were measured, the conjugate length was 14.0 mm, and the average value of the MTF at the conjugate length was 48%.

740n using this rod lens array
600 dpi using an LED having an emission wavelength of m as a light source
LED printer was assembled. Using this LED printer, a continuous printing test was performed on 1000 sheets of A4 size paper, and the first and last printings were compared. As a result, there was no change in the image, and a printing without spots was obtained. After taking out the rod lens array after the test and observing the lens end face,
No adhesion of toner or the like was observed.

Example 2 In the preparation of the stock solution for forming the first to fifth layers, instead of polyoxyethylene alkylamine (surfactant “Amate 320” manufactured by Kao Corporation), polyoxyethylene olein ether (Kao) was used. A rod lens was produced in the same manner as in Example 1 except that 0.1 part by mass of “Emulgen 404” manufactured by K.K. was added.

The radius (r) of the obtained rod lens is 0.5.
The refractive index distribution was 1.512 at the center and 1.468 at the outer periphery.

A rod lens array was manufactured in the same manner as in Example 1 using the obtained rod lens.

When the characteristics of this lens array at 12 Lp / mm and a wavelength of 740 nm were measured, the conjugate length was 14.0 mm, and the average value of the MTF at the conjugate length was 48%.

740n using this rod lens array
An LED printer using an LED having a light emission wavelength of m as a light source was assembled. Using this LED printer, a continuous printing test was performed on 1000 sheets of A4 size paper, and the first and last printings were compared. As a result, there was no change in the image, and a printing without spots was obtained. After the test, the rod lens array was taken out and the lens end face was observed. No adhesion of toner or the like was observed.

Example 3 In preparing the stock solution for forming the first to fifth layers, polyoxyethylene alkyl ether phosphoric acid was used instead of polyoxyethylene alkylamine (surfactant "Amate 320" manufactured by Kao Corporation). Potassium salt ("Electro-Strapper F" manufactured by Kao Corporation) was added to 0.
A rod lens was produced in the same manner as in Example 1 except that 05 parts by mass was added.

The radius (r) of the obtained rod lens is 0.
The refractive index distribution was 1.512 at the center and 1.468 at the outer periphery.

Using the obtained rod lens, a rod lens array was produced in the same manner as in Example 1.

When the characteristics of this lens array at 12 Lp / mm and a wavelength of 740 nm were measured, the conjugate length was 14.0 mm, and the average value of the MTF at the conjugate length was 48%.

740n using this rod lens array
An LED printer using an LED having a light emission wavelength of m as a light source was assembled. Using this LED printer, a continuous printing test was performed on 1000 sheets of A4 size paper, and the first and last printings were compared. As a result, there was no change in the image, and a printing without spots was obtained. After the test, the rod lens array was taken out and the lens end face was observed. No adhesion of toner or the like was observed.

Example 4 In the preparation of the stock solution for forming the first to fifth layers, instead of polyoxyethylene alkylamine (surfactant “Amate 320” manufactured by Kao Corporation), stearyl trimethylammonium chloride (Kao (Kao)) was used. A rod lens was produced in the same manner as in Example 1 except that 0.2 part by mass of “Coatamine 86P Conc” manufactured by KK was added.

The radius (r) of the obtained rod lens is 0.5.
The refractive index distribution was 1.512 at the center and 1.468 at the outer periphery.

Using the obtained rod lens, a rod lens array was produced in the same manner as in Example 1.

When the characteristics of this lens array at 12 Lp / mm and a wavelength of 740 nm were measured, the conjugate length was 14.0 mm, and the average value of the MTF at the conjugate length was 48%.

740n using this rod lens array
An LED printer using an LED having a light emission wavelength of m as a light source was assembled. Using this LED printer, a continuous printing test was performed on 1000 sheets of A4 size paper, and the first and last printings were compared. As a result, there was no change in the image, and a printing without spots was obtained. After the test, the rod lens array was taken out and the lens end face was observed. No adhesion of toner or the like was observed.

Example 5 In the preparation of the stock solution for forming the first to fifth layers, instead of polyoxyethylene alkylamine (surfactant "Amate 320" manufactured by Kao Corporation), stearyl betaine (Kao Corporation) was used instead. "Amphitol 86
B ") was added to produce a rod lens in the same manner as in Example 1 except that 0.05 parts by mass was added.

The radius (r) of the obtained rod lens is 0.
The refractive index distribution was 1.512 at the center and 1.468 at the outer periphery.

Using the obtained rod lens, a rod lens array was produced in the same manner as in Example 1.

When the characteristics of this lens array at 12 Lp / mm and a wavelength of 740 nm were measured, the conjugate length was 14.0 mm, and the average value of the MTF at the conjugate length was 48%.

740n using this rod lens array
An LED printer using an LED having a light emission wavelength of m as a light source was assembled. Using this LED printer, a continuous printing test was performed on 1000 sheets of A4 size paper, and the first and last printings were compared. As a result, there was no change in the image, and a printing without spots was obtained. After the test, the rod lens array was taken out and the lens end face was observed. No adhesion of toner or the like was observed.

Example 6 Example 1 was repeated except that polyoxyethylene alkylamine (surfactant “Amate 320” manufactured by Kao Corporation) was not added to the first to third layers.
A rod lens was produced in the same manner as described above.

The radius (r) of the obtained rod lens is 0.5.
The refractive index distribution was 1.512 at the center and 1.468 at the outer periphery.

Using the obtained rod lens, a rod lens array was produced in the same manner as in Example 1.

When the characteristics of this lens array at 12 Lp / mm and a wavelength of 740 nm were measured, the conjugate length was 14.0 mm, and the average value of the MTF at the conjugate length was 48%.

740n using this rod lens array
An LED printer using an LED having a light emission wavelength of m as a light source was assembled. Using this LED printer, a continuous printing test was performed on 1000 sheets of A4 size paper, and the first and last printings were compared. As a result, there was no change in the image, and a printing without spots was obtained. After the test, the rod lens array was taken out and the lens end face was observed. No adhesion of toner or the like was observed.

Comparative Example 1 Same as Example 1 except that polyoxyethylene alkylamine (surfactant “Amate 320” manufactured by Kao Corporation) was not added in the preparation of the first to fifth layer forming stock solutions. To produce a rod lens.

The radius (r) of the obtained rod lens is 0.
The refractive index distribution was 1.512 at the center and 1.468 at the outer periphery.

Using the obtained rod lens, a rod lens array was produced in the same manner as in Example 1.

When the characteristics of this lens array at 12 Lp / mm and a wavelength of 740 nm were measured, the conjugate length was 14.0 mm, and the average value of the MTF at the conjugate length was 48%.

740n using this rod lens array
An LED printer using an LED having a light emission wavelength of m as a light source was assembled. Using this LED printer, a continuous printing test was performed on 1,000 sheets of A4 size paper, and the first and last printings were compared. The first print had no problem, but the last image had irregular prints and spots.
After the test, the rod lens array was taken out and the lens end face was observed. As a result, toner adhesion was observed.

(Example 7) Polymethyl methacrylate 4
7 parts by mass, 30 parts by mass of tricyclo [5.2.1.0 ^2,6 ] decanyl methacrylate, 23 parts of methyl methacrylate
Parts by mass, 0.25 parts by mass of 1-hydroxycyclohexyl phenyl ketone, 0.2 polyoxyethylene alkylamine (surfactant "Amate 320" manufactured by Kao Corporation) 0.2
Parts by mass and 0.1 parts by mass of hydroquinone were heated and kneaded at 70 ° C. to prepare a first layer forming stock solution.

50 parts by mass of polymethyl methacrylate, 10 parts by mass of tricyclo [5.2.1.0 ^2,6 ] decanyl methacrylate, 40 parts by mass of methyl methacrylate,
0.25 parts by mass of hydroxycyclohexyl phenyl ketone, 0.2 parts by mass of polyoxyethylene alkylamine (surfactant "Amate 320" manufactured by Kao Corporation) and 0.1 parts by mass of hydroquinone were heated and kneaded at 70 ° C. This was used as a stock solution for forming two layers.

50 parts by weight of polymethyl methacrylate, 40 parts by weight of methyl methacrylate, 10 parts by weight of 2,2,3,3,4,4,5,5-octafluoropentyl methacrylate, 0.25 part by weight of 1-hydroxycyclohexyl phenyl ketone Parts, 0.2 parts by mass of polyoxyethylene alkylamine (surfactant “Amate 320” manufactured by Kao Corporation) and 0.1 parts by mass of hydroquinone were heated and kneaded at 70 ° C. to obtain a stock solution for forming a third layer.

50 parts by weight of polymethyl methacrylate, 40 parts by weight of methyl methacrylate, 10 parts by weight of 2,2,3,3,4,4,5,5-octafluoropentyl methacrylate, 0.25 part by weight of 1-hydroxycyclohexyl phenyl ketone Parts, polyoxyethylene alkylamine (surfactant "Amate 320" manufactured by Kao Corporation) 0.2 parts by mass, hydroquinone 0.1 parts by mass, dye Blue ACR (Nippon Kayaku Co., Ltd.) 0.12 parts by mass Part, Dye MS Yellow
0.10 parts by mass of HD-180 (manufactured by Mitsui Toatsu Dye Co., Ltd.) and 0.08 parts by mass of dye MS Magenta HM-1450 (manufactured by Mitsui Toatsu Dye Co., Ltd.) are heated and kneaded at 70 ° C. This was used as a stock solution for forming a layer.

42 parts by weight of polymethyl methacrylate, 18 parts by weight of methyl methacrylate, 40 parts by weight of 2,2,3,3,4,4,5,5-octafluoropentyl methacrylate, 0.25 part by weight of 1-hydroxycyclohexyl phenyl ketone Parts, 0.2 parts by mass of polyoxyethylene alkylamine (Surfactant “Amate 320” manufactured by Kao Corporation) and 0.1 parts by mass of hydroquinone were heated and kneaded at 70 ° C. to prepare a fifth layer forming stock solution.

The five stock solutions were sequentially arranged from the center so that the refractive index after curing became lower, and were simultaneously extruded from a concentric five-layer composite spinning nozzle. The temperature of the composite spinning nozzle is 56 ° C., and the discharge ratio of each layer is the ratio of the thickness (first layer is radius) of each layer in the radial direction of the rod lens, and the first layer / second layer / third layer / 4th layer / 5th layer = 18/50/26
/ 5/1.

Next, the state of the yarn extruded from the composite spinning nozzle is taken up by a nip roller (200 cm /
Minute), passing through a 55 cm long interdiffusion treatment part, and then above the center of a curing treatment part (light irradiation part) in which twelve 120 cm long, 40 W chemical lamps are arranged at equal intervals around the central axis. The mixture was hardened by passing through a fibrous body and wound around a winding section. The radius of the obtained yarn of the rod lens is 0.3.
It was 0 mm. The raw yarn was stretched 4 times at 130 ° C. and relaxed at 150 ° C. by 20% to obtain a plastic rod lens.

The radius of the obtained rod lens is 0.17 m
m, the refractive index is 1.497 at the center and 1.486 at the outer periphery
Met.

The 678 rod lenses were arranged in a row between phenolic resin substrates (thickness: 0.5 mm), and an adhesive (carbon black was added so as to contain 2% by mass of carbon black) in the gap. Epiform (product name,
Somar))) and the adhesive was cured. Then, both ends are cut and polished, and the lens length is 4.4 mm.
Was manufactured.

The wavelength of this rod lens array is 525 nm.
The conjugate length in was 10.0 mm. The average value of the 12 Lp / mm MTF at the conjugate length is 65% at a wavelength of 470 nm, 75% at a wavelength of 525 nm, and 6% at a wavelength of 630 nm.
3%.

This plastic rod lens array was
A 600 dpi color scanner was fabricated by assembling into a 00 dpi color image sensor head. When an image was read in 600 dpi color using this color scanner, a clear read image without bleeding or spots was obtained. Using this color scanner, 1000 sheets were scanned, and the scanned image after scanning was a clear image without spots. When the rod lens array was taken out of the color scanner and the lens end face was observed, no adhesion of dust or the like was observed.

[0101]

The rod lens of the present invention contains an antistatic agent therein and thus has a small charge amount. For this reason,
The rod lens array of the present invention has little adhesion of toner and dust to the lens end surface, and can obtain a printed image and a read image with less spots for a long period of time even when used in a high-resolution LED printer or scanner. Also, maintenance work is reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view of a rod lens of the present invention.

FIG. 2 is a schematic configuration diagram of a molding apparatus for manufacturing the rod lens of the present invention.

FIG. 3 is a perspective view of one embodiment of a rod lens array of the present invention.

FIG. 4 is a schematic configuration diagram of an apparatus for measuring the resolution (MTF) of a rod lens array.

FIG. 5 is a diagram showing a grid image of an optical transmitter array read by a CCD line sensor of a resolution measuring device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lens 2 Central axis 10 Concentric composite spinning nozzle 11 Uncured filament 12 Mutual diffusion part 13 Curing part 14 Take-off roller 15 Rod lens 16 Winding part 17 Inert gas inlet 18 Inert gas outlet 19 Rod lens Reference Signs List 20 substrate 21 light source 22 filter 23 diffusion plate 24 lattice 25 rod lens array 26 CCD line sensor

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 1/028 1/036 (72) Inventor Takashi Saeki 20-1 Miyukicho, Otake City, Hiroshima Prefecture Mitsubishi Rayon Central Technical Research Institute, Inc. F-term (reference) 2C162 AE28 FA04 FA17 FA45 FA50 5C051 AA01 AA02 BA04 CA08 DB01 DB02 DB22 EA08 FA01 FA06

Claims (4)

[Claims] 1. A rod lens having a refractive index distribution in which a refractive index decreases continuously from a center to an outer peripheral portion and containing an antistatic agent. 2. A rod lens array in which the rod lenses according to claim 1 are arranged. 3. An LED printer comprising the rod lens array according to claim 2. 4. A scanner comprising the rod lens array according to claim 2.