JP2000035519A - Optical transmission body, optical transmission body array and image sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical transmission body having a large lens diameter, a short conjugate length and a deep depth of focus. SOLUTION: This is a cylindrical optical transmission body 1 having a distribution approximated by a quadratic curve in which a radius r is 0.2 mm-0.45 mm and at least a refractive index distribution at 0.3r-0.7r from a center axis 4 is stipulated by n (L) =n0 1-(g2/2)L2} (provided that, n0 is a refractive index in the center axis of an optical transmission body, L is a distance (0<=L<=r) from the center axis of the optical transmission body; g is a refractive index distribution constant of the optical transmission body and n (L) is a refractive index at the position to a distance L from the center axis of the optical transmission body). The constant g satisfies 0.35 mm-1<=g<=0.5 mm-1 and 0.10<=g.r<=0.16 at a wave length of 570 nm. A photo-absorbent coexistence layer 2 having 50 μm or more thickness is formed in the region within 100 μm range from the outer circumference toward the center axis, within the range of 0.6r or more outside from the center axis and including the range of 0.8r-0.95r.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical transmission technique among optical techniques, and more particularly to a gradient index optical transmission body, an optical transmission array, and an image sensor using the same.

[0002]

2. Description of the Related Art A graded-index optical transmitter array (rod lens array) has features such as short conjugate length, brightness, and low cost.
It is used as a small, equal-size imaging element in X, LED printers and the like. However, the conventional rod lens array has a drawback that the depth of focus is shallow, except for some varieties that have a relatively long conjugate length and a small numerical aperture and are dark. For this reason, the rod lens array has conventionally been used in a contact type image sensor mainly used for a facsimile, a sheet feed scanner or the like in which a document surface is fixed.

In image scanners such as handy scanners and flatbed scanners, it is necessary to increase the depth of focus. Therefore, a glass rod lens array having a small aperture angle and a long conjugate length is used. System configuration has been done. For this reason, first, the apparatus must be large, and second, the amount of light that can be captured is very small, and it is necessary to supplement the brightness. In order to reduce the size of the apparatus, a glass rod lens with a smaller lens diameter and a shorter conjugate length has recently been sold, but this rod lens does not sufficiently improve the depth of focus characteristic.

For this reason, there is a demand for the development of a rod lens having a good depth of focus characteristic (that is, having a certain depth of focus) and a short conjugate length, which can be used for a handy scanner, a flatbed type scanner and the like. I have.

Japanese Patent Application Laid-Open No. Hei 6-291943 discloses a method of improving the depth of focus characteristic. In this publication, a light-blocking member is provided on at least one of the light incident end face and the light output end face of the rod lens array to block light having a large incident / exit angle, thereby reducing the amount of blur when defocusing occurs. Further, an image input device having a large depth of focus is shown.

On the other hand, techniques for introducing a light absorber into an optical transmission body are disclosed in Japanese Patent Application Laid-Open Nos. Hei 4-251805 and Hei 1-10.
It is disclosed in JP-A-5202. JP-A-4-2518
No. 05 describes a refractive index distribution type optical transmission body obtained by multilayer-spinning a plurality of spinning solutions having different dye concentrations, and the dye is present throughout the inside of the optical transmission body. JP-A-1-105202 describes an optical transmitter in which a layer containing a light absorbing substance is formed below the surface.
Japanese Patent Application Laid-Open No. Hei 9-127353 describes an optical transmitter in which a light absorber is contained at a uniform concentration within a predetermined range of 100 μm from the outer peripheral surface toward the center.

[0007]

However, in the image input apparatus described in Japanese Patent Application Laid-Open No. 6-291943, it is necessary to attach a light shielding member to the light input / output end face in addition to the rod lens array itself. There is a problem that it is difficult to manufacture it precisely and to attach it to the rod lens array precisely.

The optical transmitter disclosed in Japanese Patent Application Laid-Open No. Hei 4-251805 aims to make the light quantity distribution of the light emitted from the optical transmitter uniform, and the dye is provided with a concentration distribution inside the optical transmitter. To absorb light in the entire area of the optical transmission body. Therefore, this optical transmitter does not serve the purpose of simultaneously satisfying the short conjugate length and the brightness.

The optical transmitters described in JP-A-1-105202 and JP-A-9-127353 are intended to absorb flare light, and have a focusing parameter (refractive index distribution constant) g. It is too large and the conjugate length is short, but is insufficient in terms of depth of focus characteristics. That is, this 2
The two techniques do not contribute to improving the depth of focus characteristics.

In addition, the above-mentioned problems of the conventional image scanner using a combination of the light transmitter array and the LED light source or the white light source cannot be solved by the light transmitter or the light transmitter array of the two technologies.

In an actual glass rod lens array (Micro Opto, Selfoc lens array), SLA20, SLA12, SLA9 and SLA6 are used.
Such products are lined up, and Table 1 shows their conjugate length and depth of focus characteristics.

[0012]

[Table 1] The aperture angle determines the amount of light that can be captured by the lens. As the aperture angle increases, the light amount value increases and the conjugate length also decreases, but it can be seen that the depth of focus is shallow. Here, when forming a contact image sensor, the conjugate length is required to be 20 mm or less. The lenses having the aperture angles of 9 degrees and 6 degrees described above have a relatively large depth of focus but a too long conjugate length, and are difficult to apply to a contact image sensor. In the case of the SLA 12D having an aperture angle of 12 degrees, the conjugate length is not more than 20 mm, but the depth of focus is an insufficient value of ± 0.6 mm. The value that determines these opening angles is the value of gr.
When the same material is used to provide a refractive index distribution,
The value of r is the same. Therefore, in order to shorten the conjugate length, g is generally reduced by reducing the lens diameter.
G is increased using the constant r relationship. However, the depth of focus characteristic of the small-diameter lens thus obtained is almost the same as the original large-diameter lens. For this reason, a lens having a short conjugate length and a large depth of focus has been manufactured by using a lens material that reduces g · r and reducing the lens diameter. However, such a lens having a small diameter not only reduces the amount of light taken in, but also makes it extremely difficult to align the optical axis with a light source and a light receiving sensor when used in an image sensor. Having.

That is, conventionally, the lens diameter is somewhat large,
In addition, an optical transmitter and an optical transmitter array with a short conjugate length and a large depth of focus are not known. Also, there is no known image scanner that can clearly read an image even when the position of a document to be read is deeply shifted and does not require many light sources, and can be made compact.

[0014]

According to the present invention, as a solution to the above problems, there is provided a cylindrical optical transmission body whose refractive index decreases continuously from the central axis toward the outer periphery. And the radius r is between 0.2 mm and 0.45 mm,
Refractive index distribution following formula in the range of 0.3r~0.7r at least the central axis (1): n (L) = n 0 {1- (g 2/2) L 2} ····· (1 (Where n ₀ is the refractive index at the central axis of the optical transmitter, and L is the distance from the central axis of the optical transmitter (0 ≦ L ≦ r))
And g is the refractive index distribution constant of the optical transmitter, and n
(L) is a refractive index at a position at a distance L from the central axis of the optical transmission body), and has a distribution approximated by a quadratic curve defined by the following formula (1). Constant g
At a wavelength of 570 nm, 0.35 mm ^-1 ≤g≤
0.5 mm ⁻¹ , and 0.10 ≦ g · r ≦ 0.16, within a range of 100 μm from the outer peripheral surface toward the central axis and within a range of 0.6 r or more outside the central axis,
A light absorbing agent mixed layer having a thickness of 50 μm or more is formed in which a light absorbing agent that absorbs light in at least a part of the wavelength region of the visible light and the near infrared light is almost uniformly mixed. The agent mixture layer is at least 0.8 r to 0.9 from the central axis.
An optical transmitter characterized by being present in an area including the range of 5r.

In one embodiment of the present invention, a 4 Lp / mm lattice pattern is formed at a position where the MTF of the light transmitting body with respect to light having the maximum absorption wavelength of the light absorbing agent contained in the light absorbing agent mixed layer is maximized. When the body and the light receiving sensor are arranged in this order and only the lattice pattern is moved, the depth of focus characteristic defined as the width of the movement range of the lattice pattern at which the MTF is 40% or more is 1.35 mm or more, preferably 1.5 m.
m or more.

Further, according to the present invention, a plurality of the above-described optical transmitters are arranged in parallel with each other in a direction crossing the direction of the central axis of the optical transmitter. An optical transmitter array is provided.

Further, according to the present invention, there is provided an image sensor comprising the above-described light transmitter array and a light receiving sensor on which an image is formed by the light transmitter array.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the optical transmitter, optical transmitter array, and image sensor according to the present invention will be described.

In the present invention, an optical transmitter having specific characteristics is selected, and a light-absorbent mixed layer is arranged in a specific range in the radial direction. That is, the present invention includes a light absorber in a specific radial range of the light transmitting body, and narrows the effective element diameter of the light transmitting body for light in the absorption wavelength range of the light absorbing body to thereby reduce the wavelength of the light transmitting body. It is characterized by improving the resolution and increasing the depth of focus of the optical transmission body. When the absorption wavelength range of the light absorber is only a specific wavelength range of visible light and near-infrared light, the specific wavelength range is set to the emission wavelength of the light source used in combination with the optical transmitter. When the absorption wavelength range of the light absorber is the entire wavelength range of visible light and near-infrared light, the effective diameter of the optical transmission body can be narrowed down for light in the entire wavelength range.

Further, since the amount of light emitted from the light transmitting body can be adjusted by the concentration of the light absorbing agent and the size of the light absorbing agent mixed layer, it is necessary to adjust the concentration of these light absorbing agents and the size of the light absorbing agent mixed layer. Thus, a relatively large amount of emitted light can be maintained. The depth of focus is also determined by the concentration of the light absorbing agent and the size of the light absorbing agent mixed layer. That is, when the concentration of the light absorbing agent decreases, the amount of emitted light increases, but the depth of focus decreases. Also, when the concentration of the light absorbing agent increases, the amount of emitted light decreases, but the depth of focus increases. Further, as the size of the light absorbing agent mixed layer increases, the amount of emitted light decreases, but the depth of focus increases. Also, as the size of the light-absorbent mixed layer decreases, the amount of emitted light increases, but the depth of focus decreases.

The optical transmission body of the present invention is a columnar refractive index distribution type optical transmission body whose refractive index decreases continuously from the central axis toward the outer periphery. 1 and 2 are a cross-sectional view on a plane including a central axis and a cross-sectional view on a plane orthogonal to the central axis of an embodiment of a gradient index optical transmission body (hereinafter, appropriately referred to as a lens) according to the present invention. . When the refractive index on the central axis 4 is n ₀ and the refractive index distribution constant is g, the optical transmission body 1
Is a refractive index n (L) at a distance L in the radial direction from
Substantially following equation (1): with _{n (L) = n 0 {} 1- (g 2/2) L 2} ····· transparent cylinder having a refractive index distribution represented by the relationship (1) is there.

The optical transmitter according to the present invention has a refractive index distribution that can be approximated by equation (1) at least in the range of 0.3r to 0.7r from the center, where r is the radius. 1 and 2, the light-absorbing agent-mixed layer 2 is indicated by hatched portions. For light in the wavelength range absorbed by the light absorbing agent in the light absorbing agent mixed layer 2, the effective diameter of the lens is narrowed to a portion inside the light absorbing agent mixed layer 2 (a portion close to the central axis 4). I have.

The light absorbing agent is located on the outer peripheral surface side of the light transmitting body 1.
It is mixed in a predetermined portion within a range of 0 μm. By the way, the optical transmission body manufactured by the conventional method includes a portion having an irregular refractive index distribution in an outer peripheral portion. The portion to which the light absorber is added may include not only a portion having an irregular refractive index distribution at the outer peripheral portion but also a portion having a good refractive index distribution. However, it is not preferable to add the light absorbing agent from the outer peripheral surface to the center side beyond 100 μm because the amount of light transmitted through the optical transmission body is significantly reduced.

In the present invention, the thickness of the light absorbing agent mixed layer 2 is 50 μm or more. The thickness of the light absorbent mixed layer 2 is 50
When the thickness is less than μm, the effect of improving the depth of focus characteristic is small, which is not preferable.

The optical transmitter 1 has a wavelength of 570 nm and a wavelength of 0.1.
0 ≦ g · r ≦ 0.16. This value is related to the aperture angle as described above, and if this value is too small, the original aperture angle is narrowed, so that the depth of focus becomes good, but the optical transmission body has The amount of light decreases, and it becomes difficult to align the optical axis with the light source and the light receiving sensor. Also, g · r>
In the case of 0.16, it is not possible to obtain a good depth of focus characteristic which is the object of the present invention.

In the present invention, the radius r of the optical transmission body is
0.2 mm ≦ r ≦ 0.45 mm and wavelength 57
The g value at 0 nm is 0.35 mm ⁻¹ ≦ g ≦ 0.5 m
m ⁻¹ , preferably 0.25 mm ≦ r ≦ 0.35
mm and 0.4 mm ⁻¹ ≦ g ≦ 0.5 mm ⁻¹ .
When the refractive index distribution constant g is constant, the smaller the radius r, the narrower the viewing radius and the deeper the depth of focus. However, when the radius r is smaller than 0.2 mm, it is very difficult to handle when manufacturing a lens array. In addition, when the center of the light source and the light receiving sensor is deviated during the manufacturing of the image sensor, the image sensor is easily affected, so that the production control of the image sensor becomes difficult. Radius r is 0.2
If it is 5 mm or more, the easiness of handling and the adverse effect of the center shift at the time of manufacturing the image sensor are extremely reduced. Further, when the radius r is larger than 0.45 mm, the aperture angle of the optical transmission body increases and the degree of blurring of the image of the original optical transmission body increases. Is small. In order to obtain a greater effect of improving the depth of focus characteristic, the radius r is desirably 0.35 mm or less.

The light-absorbent mixed layer is disposed outside the center axis 4 by more than 0.6 r. The light-absorbent mixed layer is arranged so as to include at least the entire range of 0.8r to 0.95r from the central axis 4. The light absorbing agent should have a center axis 4
If it is contained on the side, the amount of emitted light decreases. Therefore, the light absorber is not contained on the central axis side of 0.6r or more. In the range outside the center axis 4 and less than 0.6r, the light absorbing agent-containing region is appropriately set according to the wavelength characteristics and the amount of emitted light required for the optical transmitter. On the other hand, with the current industrial production technology, it is difficult to manufacture the optical transmission body 1 whose refractive index distribution is approximated by the equation (1) over the entirety. Therefore, in the current optical transmission body, an irregular portion of the refractive index distribution is formed on the outer peripheral portion during manufacturing. The irregular portion of the outer refractive index distribution is a portion where the contribution to the imaging of the lens is low, and this portion may be introduced with a black light absorbing agent or a light diffusing agent for the purpose of removing flare light or the like. I can do it. Also, that part can be physically deleted.

Since the thickness of the light absorber mixed layer 2 of the light transmitter 1 is 50 μm or more, the MTF of the light transmitter with respect to the light having the maximum absorption wavelength of the light absorber contained in the light absorber mixed layer.
When the lattice pattern of 4 Lp / mm, the optical transmitter, and the light receiving sensor are arranged in this order at the position where the maximum value is obtained, and only the lattice pattern is moved, the width of the movement range of the lattice pattern at which the MTF becomes 40% or more is defined. The depth of focus characteristic is usually 1.35 mm or more. When a plurality of types of light absorbers are mixed and used in the light absorber mixed layer, the maximum absorption wavelength when measuring MTF is not the maximum absorption wavelength of each light absorber, but the mixed light. The maximum absorption wavelength of the absorber is used. By appropriately changing the amount of the light absorbing agent added and the thickness of the light absorbing agent mixed layer, it is possible to obtain a lens having a depth of focus of 1.5 mm or more.

In the MTF, a grating pattern is imaged on a light-receiving sensor by an optical transmitter and read, and the maximum value (i _MAX ) and the minimum value (i _MIN ) of the measured light amount are measured. %] = ｛(I _MAX −i _MIN ) / (i _MAX + i
_MIN )｝ × 100. The 4 Lp / mm grid pattern is a set of white lines and black lines (line pair [Lp]).
Indicates a grid pattern provided in four sets in a width of 1 mm.

As the light absorber, those that absorb only a specific wavelength range among visible light and near-infrared light can be used, and those that absorb the entire wavelength range can also be used. The range (wavelength width) of the specific wavelength region is not particularly limited, but is preferably in the range of 200 nm or less.
The range of 0 nm or less is more preferable. The specific wavelength region may be set to a plurality of discontinuous regions. For example, a specific wavelength range of 400 to 500 n to absorb red and blue light.
m and a wavelength of 600 to 700 nm. In that case, the width of each specific wavelength range is 200 nm.
It is preferably in the following range, and more preferably in the range of 100 nm or less.

The following are typical examples of the light absorbing agent that absorbs only a specific wavelength range. 600-700
Diaresin Blue manufactured by Mitsubishi Chemical with absorption in nm
e4G and similar products from other companies in the industry. 550-65
Kayaset Blu manufactured by Nippon Kayaku having absorption at 0 nm
e ACR and similar products from other companies in the industry. Light absorbers effective in other wavelength ranges include 400 to 5
As a material having an absorption at 00 nm, Nippon Kayaku Kaya
sorb Yellow 2G, Orange G, Y
MS Yel of Mitsui Toatsu Dye, an equivalent of yellow AG and Yellow EG and their respective competitors
low HD-180 and its competitors. Kayasorb Red G, Red 13 manufactured by Nippon Kayaku Co., Ltd.
0, Red B and its competitors, and Mitsui Toatsu Dye MS Magenta HM-1450 and its competitors. These dyes can be used alone or in combination of two or more.

As the light absorbing agent that absorbs the entire wavelength range, for example, a black dye can be used, and a light absorbing agent that absorbs only a specific wavelength range, and a light absorbing agent that absorbs different wavelength ranges is used. A mixture of a plurality of types can also be used.

In the light transmitting body of the present invention, the amount of the light absorbing agent used is proportional to the effect. Among the light passing through the light transmitting body containing the light absorbing agent, the light amount in the wavelength range absorbed by the light absorbing agent is at least compared with the light amount in the same wavelength range passing through the light transmitting body not containing the light absorbing agent. If it is reduced by about 30%, a practically sufficient effect can be obtained. However, preferably 5
It is desirable that it is reduced by 0% or more, more preferably 80% or more.

The optical transmitter array according to the present invention can be manufactured by a conventionally known method using the optical transmitter 1 described above. That is, as shown in FIG. 3, a plurality of optical transmission bodies 1 are arranged in a row in a direction crossing the direction of the central axis of the optical transmission body 1 and preferably in a direction orthogonal thereto, or a plurality of optical transmission bodies 1 are arranged in parallel. The shape, material, and the like of the array 5 are not limited as long as the rows are arranged so as to be parallel to each other. In FIG. 3, an adhesive for joining the optical transmission bodies 1, side plates for maintaining the array of the optical transmission bodies 1, and the like are omitted.

As shown in FIG. 4, the image sensor according to the present invention has the above-described optical transmitter array 5 and a light receiving sensor 32. It is preferable to arrange a light source 31 for illuminating the read document 33. While moving the read document 33 in the direction of the arrow relatively to the image sensor as described above (the document 33 may be stopped and the image sensor may be moved in the direction opposite to the arrow),
The image of the read document 33 illuminated by the light source 31 is formed on the light receiving sensor 32 by the optical transmitter array 5,
read. This image sensor has a deeper depth of focus than a conventional image sensor. Further, as the light source 31, an LED light source or a white light source can be used. A large number of LED light sources arranged in an array can be used, and a cold cathode tube or the like can be used as a white light source. Further, as the light receiving sensor 32, any of a monochrome sensor and a primary color sensor can be used regardless of whether an LED light source or a white light source is used.

The optical transmitter 1 of the present invention can be manufactured, for example, as follows.

After curing, _N uncured products having a refractive index of n ₁ , n ₂ ,..., _{N N} (N is an integer of 3 or more) are prepared. When laminating and shaping the uncured material in this order from the center to the outer periphery, layers on the outer periphery after the shaping, preferably N, N-1, N-2,.
The light absorbing agent is mixed into at least a layer of the second layer that includes a region in the range of 0.8r to 0.95r, where r is the radius of the light transmitting body 1 after shaping. These uncured materials are arranged in such a manner that the refractive index decreases sequentially from the center toward the outer peripheral surface, and are formed into an uncured laminate (hereinafter, appropriately referred to as a "filament") which is formed in a concentric multilayer structure. Shape. Next, the filamentous material is manufactured by performing a mutual diffusion process of a substance between adjacent layers so that a refractive index distribution between each layer becomes a continuous distribution, or after performing a mutual diffusion process, and then curing the filamentous material. You.

In order to make the refractive index distribution of the obtained optical transmission body close to the ideal distribution, N is preferably 4 or more. Also, considering the ease of manufacture, N is preferably about 6 or less. However, N can be set to 10 or more in order to obtain a high-performance optical transmission body 1. The thickness of each layer may be different or may be the same.

The uncured substance used in the present invention preferably has a viscosity of 10 ³ to 10 ⁸ poise and is curable. If the viscosity is too low, thread breakage occurs during shaping, and it is 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.

As the substance constituting the uncured product, a radical polymerizable vinyl monomer or a composition comprising the monomer and a polymer soluble in the monomer can be used.

Specific examples of the radical polymerizable vinyl monomer include methyl methacrylate (n = 1.49), styrene (n = 1.59), chlorostyrene (n = 1.61),
Vinyl acetate (n = 1.47), 2,2,3,3-tetrafluoropropyl (meth) acrylate, 2,2,3,3,4,4,5,5-octafluoropentyl (meth) acrylate, 2,2,3,4,4,
4-hexafluorobutyl (meth) acrylate, 2,2,2-
Fluorinated alkyl (meth) acrylates such as trifluoroethyl (meth) acrylate (n = 1.37 to 1.4
4), (meth) acrylates having a refractive index of 1.43 to 1.62, for example, ethyl (meth) acrylate, phenyl (meth) acrylate, benzyl (meth) acrylate, hydroxyalkyl (meth) acrylate, alkylene glycol (meth) acrylate , Trimethylolpropane di or tri (meth) acrylate, pentaerythritol di, tri or tetra (meth) acrylate,
Examples include diglycerin tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, diethylene glycol bisallyl carbonate, fluorinated alkylene glycol poly (meth) acrylate, and various (meth) acrylates having an alicyclic group.

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 vinyl monomer and a soluble polymer.

The polymer which can be used here must have good compatibility with the polymer produced from the above-mentioned radical polymerizable vinyl monomer. For example, polymethyl methacrylate (n = 1.49), polymethyl methacrylate System copolymer (n = 1.47-1.50), poly 4-methylpentene-1 (n = 1.46), ethylene / vinyl acetate copolymer (n = 1.46-1.50), polycarbonate ( n = 1.50 to 1.57), polyvinylidene fluoride (n = 1.42), vinylidene fluoride / tetrafluoroethylene copolymer (n = 1.42 to 1.46), vinylidene fluoride / tetrafluoro Examples include an ethylene / hexafluoropropene copolymer (n = 1.40 to 1.46), a polyfluoroalkyl (meth) acrylate polymer, and the like.

In order to adjust the viscosity, it is preferable to use a polymer having the same refractive index for each layer, since a plastic optical transmission body having a continuous refractive index distribution from the center toward the outer periphery can be obtained. In particular, since polymethyl methacrylate has excellent transparency and a high refractive index of itself, it is suitable as a polymer to be used for producing the gradient index optical transmission body of the present invention.

In order to cure the filamentous material formed from the uncured material, it is preferable to add a thermosetting catalyst or a photocuring catalyst to the uncured material. An azo-based catalyst is used. Photocuring catalysts include benzophenone, benzoin alkyl ether, 4'-isopropyl-2-hydroxy-2-methylpropiophenone, 1-hydroxycyclohexyl phenyl ketone, benzyl methyl ketal, 2,2-diethoxyacetophenone, chlorothioxanthone, and thioxanthone Compounds, benzophenone-based compounds, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, N-methyldiethanolamine, triethylamine and the like.

Next, in order to cure the uncured material, ultraviolet rays are preferably applied from the surroundings in the cured portion, and the filament containing the thermosetting catalyst and / or the photocuring catalyst is subjected to a thermosetting treatment or a photocuring treatment. .

In the method for producing the light transmitting body 1 of the present invention, the magnitude relationship between the molecular weights of the light absorbing agent and the monomer is not particularly limited.
However, when using a mixture of the monomer and the polymer as an uncured product and using the above as a light absorber, the light absorber has a much larger molecular weight than the monomer. Therefore, the diffusion rate in the uncured material is much lower. Therefore, in this case, the monomer can be diffused between the uncured material layers without substantially diffusing the light absorbing agent. That is, it is possible to obtain an optical transmitter having a substantially uniform uniformity of the substantial concentration of the light absorbing agent in the radial direction.

In the case of thermal polymerization which requires a long time for the polymerization and curing, the light absorber diffuses, the light absorber concentration in the light absorber mixed layer 2 becomes non-uniform, and the refractive index distribution is normal. There is a possibility that the light absorbing agent or the like moves to an undesired portion and the light transmitting function of the optical transmission body 1 is impaired. For this reason, it is desirable to cure by photopolymerization which can be polymerized in a short time.

To polymerize and cure by photopolymerization, it is necessary to transmit light for photopolymerization in the uncured material layer. However, there are many types of light absorbers, and the wavelength dependence of light absorption varies. That is, there is a light absorbing agent that absorbs the light transmitted by the light transmitting body 1 and absorbs the light used for polymerization at least as much as that. Therefore, in the case of carrying out the polymerization curing treatment by the photopolymerization method, it is desirable to use a light absorbing agent having a property of absorbing the transmission light of the optical transmission body 1 but transmitting the polymerization light as little as possible.

The light actually used as the transmission light of the optical transmitter 1 is usually in the range of visible light having a wavelength of 400 to 750 nm to near infrared light. On the other hand, the emission wavelength of light used for photopolymerization is usually ultraviolet light of 300 to 370 nm. Therefore, the absorbance coefficient in the wavelength range of 400 to 750 nm is 300
It is preferable to use a light absorbing agent having an absorbance coefficient at twice or more at 370 nm or more.

The optical transmission body 1 of the present invention can be manufactured by using, for example, a filament forming apparatus shown in FIG. FIG.
FIG. 1 is a schematic configuration diagram of a filament forming apparatus, showing an interdiffusion unit 1;
2 and only the hardening portion 13 are shown in a longitudinal sectional view. In the figure, reference numeral 10 is a concentric composite nozzle, 11 is an extruded uncured filament, 12 is a mutual diffusing part for diffusing monomers of each layer of the filament to give a refractive index distribution, 13 Is a curing section for curing the uncured material,
14 is a take-off roller, 15 is a manufactured optical transmission body,
Reference numeral 16 denotes a winding section, 17 denotes an inert gas inlet, and 18 denotes an inert gas outlet. In order to remove volatile substances released from the filament 11 from the interdiffusion section 12 and the hardening section 13, an inert gas such as nitrogen gas is introduced from the inert gas inlet 17.

The light source used for photopolymerization is 150 to 60
Examples thereof include 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, and a laser beam that generate light having a wavelength of 0 nm.

[0053]

The present invention will be described in detail with reference to the following examples. In the examples and comparative examples, the measurement of the refractive index distribution was performed by a known method using an Interfaco interference microscope manufactured by Carl Zeiss.

Example 1 Polymethyl methacrylate ([η] = 0.40, MEK
Medium, measured at 25 ° C .: [η] of polymethyl methacrylate is the same) 52 parts by weight, benzyl methacrylate 35 parts by weight, methyl methacrylate 13 parts by weight, 1-
0.25 parts by weight of hydroxycyclohexylphenyl ketone and 0.1 part by weight of hydroquinone were heated and kneaded at 70 ° C. to prepare a first layer forming stock solution. 51 parts by weight of polymethyl methacrylate, 33 parts by weight of benzyl methacrylate, 16 parts by weight of methyl methacrylate Parts, 1-hydroxycyclohexyl phenyl ketone 0.25 parts by weight, and hydroquinone 0.1 parts by weight were heated and kneaded at 70 ° C. to prepare a second layer forming stock solution, polymethyl methacrylate 50 parts by weight, benzyl methacrylate 30 parts by weight, 20 parts by weight of methyl methacrylate, 0.25 part by weight of 1-hydroxycyclohexyl phenyl ketone, 0.1 part by weight of hydroquinone
50 parts by weight of polymethyl methacrylate, 15 parts by weight of benzyl methacrylate, 35 parts by weight of methyl methacrylate, 0.25 parts by weight of 1-hydroxycyclohexyl phenyl ketone 0.25 parts by weight of hydroquinone 0.1 Parts by weight, dye B manufactured by Mitsubishi Chemical Corporation
lu4G 0.01 part by weight, Nippon Kayaku Co., Ltd. Dye B
lue ACR 0.01 parts by weight, Mitsui Toatsu Dye Co., Ltd.
Dye MS MS Yellow HD-180 0.01 parts by weight, Mitsui Toatsu Dye Co., Ltd. Dye MS Magenta
0.01 part by weight of HM-1450 was heated and kneaded at 70 ° C. to prepare a stock solution for forming a fourth layer, 42 parts by weight of polymethyl methacrylate, 18 parts by weight of methyl methacrylate, 2,2,
3,3,4,4,5,5-octafluoropentyl methacrylate 4
0 parts by weight, 0.25 parts by weight of 1-hydroxycyclohexyl phenyl ketone, and 0.1 parts by weight of hydroquinone
The mixture was heated and kneaded at a temperature of 5 ° C. to form a fifth layer forming stock solution. The five kinds of stock solutions were sequentially arranged from the center so that the refractive index of the uncured product became lower from the center by using a concentric five-layer composite nozzle, and were simultaneously extruded.

The temperature of the composite spinning nozzle was 48 ° C.
The discharge ratio of each layer is 48/14/16 /
21/1. Then, each layer is passed through a 30 cm-long interdiffusion treatment section, and then 12 chemical lamps each having a length of 120 cm and 40 W are passed through a strand fiber through the center of a light irradiation curing treatment section 13 which is arranged at equal intervals in a circular shape.
It was picked up by a nip roller at a speed of 0 cm / min.
The nitrogen flow rate in the mutual diffusion processing section 12 is 80 L / min.
Met.

The obtained optical transmitter has a radius r of 0.30 mm.
And the refractive index is 1.512 at the center and 1.5 at the outer periphery.
04. This optical transmission body is 0.15r to 0.75r.
It can be approximated by equation (1) in the range of r and g at 570 nm
= 0.43 mm ^-1 . The light-absorbing agent-mixed layer 2 in which the dye was present almost uniformly in the region of 0.78 r to 0.99 r from the central axis 4 of the light transmitting body 1 was formed with a thickness of about 63 μm.

Using a plurality of these optical transmission bodies, a phenol resin (1.2 mm thick) on both side plates, and an epiform (manufactured by Somar) containing 2 wt% of carbon black as an adhesive. The light transmitting bodies were arranged in parallel between the plates, filled with an adhesive, the adhesive was cured, and then both end faces were cut and polished to produce a light transmitting array 5 having a lens length of 8.9 mm. When the depth-of-focus characteristic of this optical transmitter array was measured, the width of the movement range of the grating pattern where the MTF at 570 nm was 40% or more with respect to the grating pattern of 4 Lp / mm was 1.40 mm. Also,
The conjugate length at a wavelength of 570 nm was 18.5 mm.

This optical transmitter array and 570 nm LED
Then, a 570 nm monochrome hand scanner was manufactured using the light receiving sensor. When newspaper articles were read using this hand scanner, fine letters could be clearly read. In addition, the characters could be read relatively clearly even in the portion where the document slightly floated.

Example 2 In Example 1, the dye added to the fourth layer was 0.03 parts by weight of dye Blue4G manufactured by Mitsubishi Chemical Corporation, 0.03 parts by weight of dye ACR manufactured by Nippon Kayaku Co., Ltd. Dye MS Yellow HD-18 manufactured by Mitsui Toatsu Dye Co., Ltd.
0 0.03 parts by weight, dye MS manufactured by Mitsui Toatsu Dye Co., Ltd.
An optical transmitter similar to that of Example 1 was obtained in the same manner as in Example 1 except that Magenta HM-1450 was changed to 0.03 part by weight.

An optical transmitter array was manufactured in the same manner as in Example 1 using a plurality of the optical transmitters. When the depth of focus characteristic of this optical transmitter array at 570 nm was measured, it was 1.65 mm.

When a Japanese-language dictionary was read using a hand scanner manufactured in the same manner as in Example 1 using this optical transmitter array, fine characters could be clearly read. In addition, the characters could be read relatively clearly even in the portion where the document slightly floated.

Example 3 The procedure of Example 1 was repeated, except that the dye to be added to the fourth layer was changed to 0.06 parts by weight of a dye, BlueACR manufactured by Nippon Kayaku Co., Ltd. An optical transmitter similar to that of Example 1 was obtained except for the dye.

An optical transmitter array was manufactured in the same manner as in Example 1 using a plurality of the optical transmitters. When the depth of focus characteristic of this optical transmitter array at 570 nm was measured, it was 1.60 mm.

When a newspaper article was read by using the optical scanner array and using a hand scanner manufactured in the same manner as in Example 1, fine characters could be clearly read. In addition, the characters could be read relatively clearly even in the portion where the document slightly floated.

Example 4 In Example 1, the dye to be added to the fourth layer was changed to 0.06 parts by weight of Dye BlueACR manufactured by Nippon Kayaku Co., Ltd., and the fifth layer was changed to Dye Blue manufactured by Nippon Kayaku Co., Ltd. ACR
An optical transmitter was obtained in the same manner as in Example 1 except that 0.06 parts by weight was added.

The obtained light transmitting body has the same radius r and refractive index distribution as those of the first embodiment, and the light in which the dye exists almost uniformly in the range of 0.78 r to r from the central axis 4 of the light transmitting body 1. The absorbent mixed layer 2 was formed with a thickness of about 66 μm.

An optical transmitter array was manufactured in the same manner as in Example 1 using a plurality of the optical transmitters. When the depth of focus characteristic of this optical transmitter array at 570 nm was measured, it was 1.60 mm.

When a newspaper article was read by using the optical scanner array and using a hand scanner manufactured in the same manner as in Example 1, fine characters could be clearly read. In addition, the characters could be read relatively clearly even in the portion where the document slightly floated.

Comparative Example 1 52 parts by weight of polymethyl methacrylate, 35 parts by weight of benzyl methacrylate, 13 parts by weight of methyl methacrylate, 0.1 part of 1-hydroxycyclohexylphenyl ketone.
25 parts by weight and 0.1 part by weight of hydroquinone were heated and kneaded at 70 ° C. to obtain a first layer forming stock solution, 48 parts by weight of polymethyl methacrylate, 10 parts by weight of benzyl methacrylate, 35 parts by weight of methyl methacrylate, 2,2, 3,3,4,4,
5,5-octafluoropentyl methacrylate 7 parts by weight,
1-hydroxycyclohexyl phenyl ketone 0.25
Parts by weight, 0.1 part by weight of hydroquinone was heated and kneaded at 70 ° C. to prepare a second layer forming stock solution, 47 parts by weight of polymethyl methacrylate, 30 parts by weight of methyl methacrylate,
23 parts by weight of 2,3,3,4,4,5,5-octafluoropentyl methacrylate, 0.25 parts by weight of 1-hydroxycyclohexyl phenyl ketone, 0.1 part by weight of hydroquinone
40 parts by weight of polymethyl methacrylate, 1 part of methyl methacrylate 1
8 parts by weight, 42 parts by weight of 2,2,3,3,4,4,5,5-octafluoropentyl methacrylate, 0.25 parts by weight of 1-hydroxycyclohexylphenyl ketone, 0.1 part of hydroquinone.
1 part by weight, Dye Blue ACR manufactured by Nippon Kayaku Co., Ltd.
0.06 parts by weight was heated and kneaded at 70 ° C. to obtain a stock solution for forming the fourth layer, which was 37 parts by weight of polymethyl methacrylate, 4 parts by weight of methyl methacrylate, 2,2,3,3,4,4,5,5. 59 parts by weight of -octafluoropentyl methacrylate, 0.25 parts by weight of 1-hydroxycyclohexyl phenyl ketone, and 0.1 part by weight of hydroquinone were kneaded at 70 ° C.
The five kinds of stock solutions, which were used as layer forming stock solutions, were sequentially arranged from the center so that the refractive index of the uncured material became lower from the center using a concentric five-layer composite nozzle, and were simultaneously extruded.

The temperature of the composite spinning nozzle was 42 ° C., and the discharge ratio of each layer was 36/37/20/6/1 in the ratio of the radial dimension. Next, a chemical lamp 12 having a length of 120 cm and a power of 40 W was passed through the interdiffusion treatment section of each layer having a length of 30 cm.
The book was passed through a strand fiber through the center of light irradiating portions arranged at equal intervals in a circular shape, and was taken out by a nip roller at a speed of 220 cm / min. The nitrogen flow rate in the interdiffusion processing section was 80 L / min.

The obtained optical transmitter has a radius r of 0.30 mm.
And the refractive index is 1.512 at the center and 1.4 at the outer periphery.
68. This optical transmission body is 0.22r to 0.78
It can be approximated by equation (1) in the range of r and g at 570 nm
= 0.89 mm ^-1 . 0. 0 from the central axis of the optical transmission body.
The light absorbent mixed layer in which the dye was present almost uniformly in the range of 93r to 0.99r was formed with a thickness of about 18 µm.

An optical transmitter array having a lens length of 4.2 mm was manufactured in the same manner as in Example 1 by using a plurality of the optical transmitters. When the depth of focus characteristic of this optical transmitter array at 570 nm was measured, it was 0.50 mm. The conjugation length at 570 nm was 9.5 mm.

When a newspaper article was read using this optical transmitter array and using a hand scanner manufactured in the same manner as in Example 1, fine characters were unclear, and portions where the original was slightly floating were blurred and almost completely unreadable. Could not read.

Comparative Example 2 In Comparative Example 1, the temperature of the composite spinning nozzle was 50 ° C., and the discharge ratio of each layer was 35/38/20/6 /
1 and change the pick-up speed with the nip roller to 120.
An optical transmitter was obtained in the same manner as in Comparative Example 1 except that cm / min and the radius of the optical transmitter were 0.47 mm.

The obtained optical transmitter has a radius r of 0.47 mm.
And the refractive index is 1.512 at the center and 1.4 at the outer periphery.
68. This optical transmission body is 0.22r to 0.78
It can be approximated by equation (1) in the range of r and g at 570 nm
= 0.57 mm ^-1 . 0. 0 from the central axis of the optical transmission body.
The light-absorbent mixed layer in which the dye was present almost uniformly in the range of 93r to 0.99r was formed with a thickness of about 28 µm.

An optical transmitter array having a lens length of 6.6 mm was manufactured in the same manner as in Example 1 by using a plurality of the optical transmitters. When the depth of focus characteristic of this optical transmitter array at 570 nm was measured, it was 0.60 mm. The conjugation length at 570 nm was 14.4 mm.

When a newspaper article was read by using the optical scanner array and using a hand scanner manufactured in the same manner as in Example 1, fine characters were unclear, and portions where the manuscript was slightly floated were almost blurred. Could not read.

Comparative Example 3 The procedure of Example 1 was repeated except that no dye was added to the fourth layer.
Dye Blue ACR 0.06 manufactured by Nippon Kayaku Co., Ltd.
An optical transmission body was obtained in the same manner as in Example 1 except that parts by weight were added.

The obtained optical transmitter has a radius r and a refractive index distribution similar to those of the first embodiment, and is 0.9 mm away from the central axis of the optical transmitter.
The light absorber mixed layer in which the dye was present almost uniformly in the range of 9r to r was formed with a thickness of about 3 µm.

An optical transmitter array having a lens length of 8.9 mm was manufactured in the same manner as in Example 1 using a plurality of these optical transmitters. The measured depth of focus characteristic of this optical transmitter array at 570 nm was 1.10 mm.

When a newspaper article was read using the optical transmitter array and using a hand scanner manufactured in the same manner as in Example 1, fine characters could be read, but portions where the manuscript slightly floated had little character. It was blurry.

Example 5 51 parts by weight of polymethyl methacrylate, 35 parts by weight of benzyl methacrylate, 14 parts by weight of methyl methacrylate, 0.1 part of 1-hydroxycyclohexylphenyl ketone.
25 parts by weight and 0.1 part by weight of hydroquinone were heated and kneaded at 70 ° C. to prepare a first layer forming stock solution. 50 parts by weight of polymethyl methacrylate, 27 parts by weight of benzyl methacrylate, 23 parts by weight of methyl methacrylate, 1-hydroxycyclohexyl 0.25 parts by weight of phenyl ketone and 0.1 part by weight of hydroquinone were heated and kneaded at 70 ° C. to prepare a stock solution for forming a second layer, 50 parts by weight of polymethyl methacrylate, 20 parts by weight of benzyl methacrylate, 30 parts by weight of methyl methacrylate, 0.25 parts by weight of 1-hydroxycyclohexyl phenyl ketone, 0.1 part by weight of hydroquinone, Nippon Kayaku Co., Ltd. dye Blue ACR 0.0
6 parts by weight were heated and kneaded at 70 ° C. to obtain a stock solution for forming the third layer, 50 parts by weight of polymethyl methacrylate, 10 parts by weight of benzyl methacrylate, 40 parts by weight of methyl methacrylate, 0.25 parts by weight of 1-hydroxycyclohexyl phenyl ketone. , 0.1 part by weight of hydroquinone, 70
42 weight parts of polymethyl methacrylate, methyl methacrylate 18
Parts by weight, 2,2,3,3,4,4,5,5-octafluoropentyl methacrylate 40 parts by weight, 1-hydroxycyclohexyl phenyl ketone 0.25 parts by weight, hydroquinone 0.1
The weight part was heated and kneaded at 70 ° C. to form a fifth layer forming stock solution. The five kinds of stock solutions were arranged using a concentric five-layer composite nozzle sequentially from the center so that the refractive index of the uncured material became lower, and simultaneously. Extruded.

The temperature of the composite spinning nozzle was 48 ° C.
The discharge ratio of each layer is 60/10/27 /
2/1.

An optical transmitter was obtained in the same manner as in Example 1 except for these conditions.

The obtained optical transmitter has a radius r of 0.30 mm.
And the refractive index is 1.512 at the center and 1.5 at the outer periphery.
04. This optical transmission body 1 has 0.15r to 0.7
Equation (1) can be approximated in the range of 5r, and g = 0.43 mm ^-1 at 570 nm. The light-absorbing agent-mixed layer 2 in which the dye was present almost uniformly in the region of 0.70 r to 0.97 r from the central axis 4 of the light transmitting body 1 was formed with a thickness of about 81 μm.

An optical transmitter array having a lens length of 8.9 mm was manufactured in the same manner as in Example 1 by using a plurality of these optical transmitters. When the depth of focus characteristic of this optical transmitter array at 570 nm was measured, it was 1.80 mm.

When a newspaper article was read by using the optical scanner array and using a hand scanner manufactured in the same manner as in Example 1, fine characters could be clearly read. In addition, the characters could be read relatively clearly even in the portion where the document slightly floated.

Example 6 47 parts by weight of polymethyl methacrylate, tricyclo [5
[ ^2.1.0.26 ] decanyl methacrylate, 30 parts by weight, 23 parts by weight of methyl methacrylate, 0.25 parts by weight of 1-hydroxycyclohexyl phenyl ketone and 0.1 part by weight of hydroquinone are heated and kneaded at 70 ° C. 48 parts by weight of polymethyl methacrylate, 23 parts by weight of tricyclo [ ^5.2.1.02,6 ] decanyl methacrylate, 29 parts by weight of methyl methacrylate, 0.1 part of 1-hydroxycyclohexyl phenyl ketone were used as a stock solution for forming one layer.
25 parts by weight and 0.1 part by weight of hydroquinone were heated and kneaded at 70 ° C. to prepare a stock solution for forming a second layer, 49 parts by weight of polymethyl methacrylate, tricyclo [5.2.1.0]
^2,6 ] decanyl methacrylate 15 parts by weight, methyl methacrylate 36 parts by weight, 1-hydroxycyclohexyl phenyl ketone 0.25 parts by weight, hydroquinone 0.1
50 parts by weight of polymethyl methacrylate, 10 parts by weight of tricyclo [ ^5.2.1.02,6 ] decanyl methacrylate, 30 parts by weight of methyl methacrylate Parts, 2,2,3,3,4,4,
5,5-octafluoropentyl methacrylate 10 parts by weight, 1-hydroxycyclohexyl phenyl ketone 0.
25 parts by weight Hydroquinone 0.1 part by weight, Mitsubishi Chemical Co., Ltd. dye 4G 0.06 parts by weight, Nippon Kayaku Co., Ltd. dye ACR 0.06 parts by weight, Mitsui Toatsu Dye Co., Ltd. dye MS Yellow HD-1
80 0.06 parts by weight, dye MS manufactured by Mitsui Toatsu Dye Co., Ltd.
0.06 parts by weight of Magenta HM-1450 was heated and kneaded at 70 ° C. to obtain a stock solution for forming a fourth layer, 42 parts by weight of polymethyl methacrylate, 18 parts by weight of methyl methacrylate, 2, 2, 3, 3, 4, 4 40 parts by weight of 5,5,5-octafluoropentyl methacrylate, 0.25 parts by weight of 1-hydroxycyclohexyl phenyl ketone, and 0.1 parts by weight of hydroquinone were heated and kneaded at 70 ° C. to form a stock solution for forming a fifth layer. Using a concentric five-layer composite nozzle, the undiluted solutions were sequentially arranged from the center so that the refractive index of the uncured material became lower, and were simultaneously extruded.

The temperature of the composite spinning nozzle was 48 ° C.
The discharge ratio of each layer is 49/9/16/2 in the ratio of the radial dimension.
4/2. An optical transmitter was obtained in the same manner as in Example 1 except for these conditions.

The obtained optical transmitter has a radius r of 0.30 mm.
And the refractive index is 1.501 at the center and 1.4 at the outer periphery.
90. This optical transmission body 1 has a thickness of 0.17r to 0.7.
Equation (1) was approximated within the range of 2r, and g at 570 nm was 0.49 mm ^-1 . The light-absorbent mixed layer 2 in which the dye was present almost uniformly in the range of 0.74r to 0.98r from the central axis 4 of the light transmitting body 1 was formed with a thickness of about 72 μm.

An optical transmitter array having a lens length of 7.8 mm was manufactured in the same manner as in Example 1 by using a plurality of these optical transmitters. When the depth of focus characteristic of this optical transmitter array at 570 nm was measured, it was 1.65 mm. The conjugation length at 570 nm was 16.4 mm.

This optical transmitter array and 470 nm, 525
A color hand scanner was prepared using an LED of 630 nm and 630 nm and a light receiving sensor. When an image of a photo book (color) was read using this hand scanner, a color image could be clearly read. In addition, a relatively clear image was obtained even in a portion where the document slightly floated.

[0093]

According to the present invention, an optical transmitter and an optical transmitter array having excellent focal depth characteristics are provided. Further, by using this optical transmitter array, an image sensor capable of reading a relatively clear image even when the distance from the document surface changes is provided.

In particular, since the optical transmitter of the present invention can obtain a good depth of focus characteristic and a relatively short conjugate length without making the radius so small, the optical transmitter array and the image sensor can be obtained by using the same. The workability when manufacturing is good.

[Brief description of the drawings]

FIG. 1 is a sectional view of an optical transmission body of the present invention.

FIG. 2 is a sectional view of the optical transmission body of the present invention.

FIG. 3 is a schematic perspective view of an optical transmitter array of the present invention.

FIG. 4 is a schematic configuration diagram of an image sensor of the present invention.

FIG. 5 is a schematic configuration diagram of a manufacturing apparatus for manufacturing the optical transmission body of the present invention.

[Brief description of reference numerals]

 DESCRIPTION OF SYMBOLS 1 Optical transmission body 2 Light absorber mixing layer 4 Central axis 5 Optical transmission body array 10 Concentric composite nozzle 11 Uncured thread 12 Mutual diffusion part 13 Curing processing part 14 Take-off roller 15 Light transmission body 16 Winding part 17 Non Active gas inlet 18 Inert gas outlet 31 Light source 32 Light receiving sensor 33 Original to be read

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) H04N 1/028 H04N 1/028 Z (72) Inventor Toshinori Sumi 20-1 Miyukicho, Otake City, Hiroshima Prefecture Mitsubishi Rayon Co., Ltd. (72) Inventor Keita Ishimaru 20-1 Miyukicho, Otake City, Hiroshima Prefecture Mitsubishi Rayon Co., Ltd. Central Research Laboratory F-term (reference) 2H046 AA06 AD09 AZ02 AZ08 2H050 AC06 AC07 AC72 AD03 5C051 AA01 BA04 DB01 DB22 DB25 DC04 DC07

Claims (5)

[Claims] 1. A cylindrical optical transmission body whose refractive index continuously decreases from a central axis toward an outer peripheral portion, wherein a radius r
There is 0.2Mm～0.45Mm, refractive index distribution in the range of 0.3r~0.7r at least the central axis is represented by the following formula (1): n (L) = n 0 {1- (g 2/2 ) L ² ｝ (1) (where n ₀ is the refractive index at the central axis of the optical transmitter, and L is the distance from the central axis of the optical transmitter (0 ≦ L ≦ r))
And g is the refractive index distribution constant of the optical transmitter, and n
(L) is a refractive index at a position at a distance L from the central axis of the optical transmission body), and has a distribution approximated by a quadratic curve defined by the following formula (1). Constant g
At a wavelength of 570 nm, 0.35 mm ^-1 ≤g≤
0.5 mm ⁻¹ , and 0.10 ≦ g · r ≦ 0.16.
A light absorbing agent mixed layer having a thickness of 50 μm or more is formed in which a light absorbing agent that absorbs light in at least a part of the wavelength region of the visible light and the near infrared light is almost uniformly mixed. The agent mixture layer is at least 0.8 r to 0.9 from the central axis.
An optical transmitter, wherein the optical transmitter is present in an area including a range of 5r. 2. A 4 Lp / mm lattice pattern, an optical transmitter and a light-receiving sensor are located at a position where the MTF of the optical transmitter for light having the maximum absorption wavelength of the optical absorber contained in the optical absorber mixed layer is maximized. When only the grid pattern is moved in order and the MTF is 40% or more, the depth of focus characteristic defined as the width of the moving range of the grid pattern is 1.35 m.
The optical transmission body according to claim 1, wherein m is equal to or greater than m. 3. The optical transmitter according to claim 2, wherein the depth of focus characteristic is 1.5 mm or more. 4. The optical transmission device according to claim 1, wherein a plurality of the optical transmission members are arranged in parallel to each other in a direction transverse to a direction of a center axis of the optical transmission members. Optical transmitter array. 5. An image sensor comprising: the optical transmitter array according to claim 4; and a light receiving sensor on which an image is formed by the optical transmitter array.