JPH0879447A - Optical device - Google Patents

Abstract

PURPOSE: To prevent crosstalk, to miniaturize the device and to reduce the price by arranging two lens arrays and a light shielding film between them. CONSTITUTION: This device is provided with a first lens array 50 composed of plural lenses 51, 52... for forming a reduced real image inverting an object, second lens array 80 composed of plural lenses 81, 82... arranged at positions corresponding to the respective lenses 51, 52... of the first lens array 50 to enlarge the reduced real image with a prescribed magnification and to turn it to an erected image, and one or plural light shielding films 34 and 38 arranged between the first and second lens arrays 50 and 80 and forming holes 61, 71... at positions facing the respective lenses 51, 52... to pass emitted beams from the respective lenses 51, 52... of the first lens array 50.

Description

Detailed Description of the Invention

[0001]

The present invention relates to an image scanner and an L
The present invention relates to an optical device for image reading or image formation used in an ED printer or the like.

As an optical device for reading an image, a reduction optical system for forming a reduced image of an original on an image sensor such as a CCD by an ordinary convex lens, and a gradient index lens array or rod lens array are used. There is a unit of a unit size optical system that forms a unit size image of a document on a long image sensor. The latter is usually called a contact optical system because the document surface and the image sensor are in a state of being extremely close to each other.

A contact optical system is advantageous when it is necessary to downsize the device, but when it is used for a portable image scanner, for example, the contact optical system is further downsized. It is necessary to plan.

[0004]

2. Description of the Related Art With a gradient index lens array or rod lens array used in an optical device of a conventional contact optical system, it is difficult to set the focal length to about several mm or less, and the actual optical path length is It requires about 15 to 20 mm.

A microlens array in which a large number of microlenses are formed on a substrate makes it possible to manufacture a short-distance focusing lens relatively easily by selecting a manufacturing process, and by using a plurality of lens arrays. It is also possible to form an erect image of the original size. Therefore, it has been proposed to project a display image of a liquid crystal display on a protective glass arranged in front of the liquid crystal display, thereby eliminating parallax due to a difference in viewing angle (Japanese Patent Laid-Open No. 63-263520).
issue).

[0006]

In order to miniaturize the above optical device, it is necessary to shorten the optical path length, but the gradient index lens array used in the conventional contact optical system. With a rod lens array, it is practically impossible to fabricate an optical path length of 10 mm or less.

Therefore, in order to apply to, for example, an ultra-compact card-type image scanner for reading a business card-sized original, miniaturization is insufficient with the conventional one, and a gradient index lens array or rod lens is used. Since the array is expensive, there is a problem that the price cannot be sufficiently low as a device for personal use.

Further, in the conventional microlens array,
It is difficult to remove the crosstalk light from the adjacent lenses, and there is a problem in that a lens array having three or more stages is required to increase the light utilization efficiency and the structure becomes complicated.

That is, as shown in FIG. 21A, when the magnification of the intermediate image is set to 1 and a lens having a two-stage structure is used, a considerable part of the light other than the central portion of the intermediate image is on the lower side. Since it goes out of the aperture of the lens, the brightness of the formed image becomes uneven. Also, crosstalk is inevitable. In order to improve this, as shown in FIG.
When the third stage intermediate lens is inserted at the position of the intermediate image (see Japanese Patent Laid-Open No. 63-263520), the uneven brightness of the image can be solved, but the structure becomes complicated and the crossing from the adjacent lens is still present. Talk is inevitable.

Instead of the conventional rod lens, it is conceivable to use an ordinary convex lens in combination with a light-shielding tubular body for preventing crosstalk. However, in such a case, since it is necessary to absorb light on the inner peripheral surface of the cylindrical body, it is difficult to manufacture it,
There is a problem that it is not suitable for mass production.

The present invention has been made in consideration of the above circumstances. By disposing two lens arrays and a light shielding film between them, crosstalk is prevented as much as possible, and the size is reduced. It is also an object of the present invention to provide an optical device that can be manufactured at low cost.

Further, according to the present invention, a single or a plurality of layers of light-shielding films are provided, and the relative positional relationship between the lens array and the light-shielding films is devised to reduce crosstalk and make the image brightness uniform. The purpose is to It is also an object of the present invention to reduce the crosstalk and improve the contrast by devising the arrangement and shape of each lens of the lens array.

Another object of the present invention is to reduce the size of the image reading device and the like by applying this optical device to the image reading device and the like. Furthermore, it is an object of the present invention to reduce the cost of an image reading device or the like using the optical device by mass-producing the optical device.

[0014]

SUMMARY OF THE INVENTION According to the present invention, there is provided a first lens array comprising a plurality of lenses forming a reduced real image that is inverted with respect to an object, and the reduced real image is magnified at a predetermined magnification and an erect image. And a second lens array formed of a plurality of lenses arranged at positions corresponding to the respective lenses of the first lens array, and between the first lens array and the second lens array. One or a plurality of light-shielding films that are arranged and have a through hole formed at a position facing each lens so that light emitted from each lens of the first lens array can pass therethrough. And an optical device for performing the same.

Here, when there is one light-shielding film, this light-shielding film may be arranged at the position of the image plane of the reduced real image formed by each lens of the first lens array. Also, the first lens array and the second lens array may be arranged substantially in the middle.

Further, in the present invention, the light-shielding film does not substantially limit the optical path of each lens of the first lens array to the corresponding lens of the second lens array, but the first lens array is used. And an optical device having an aperture width capable of substantially blocking the optical path from each lens to the adjacent lens of the corresponding lens of the second lens array.

Also, in the case where there is one light-shielding film, the present invention provides that the first lens array and one of the light-shielding films are formed on two surfaces of the first substrate, respectively.
Is formed on one surface of the second substrate, and is fixed with the surface of the first substrate on which the light shielding film is formed and the surface of the second substrate on which the second lens array is not formed facing each other. An optical device is provided.

When the light shielding film is composed of the first light shielding film and the second light shielding film, the second light shielding film is arranged between the first light shielding film and the first lens array. When the light-shielding film is composed of two light-shielding films as described above, the first light-shielding film is arranged at the position of the image plane of the reduced real image formed by each lens of the first lens array. The distance between the first light-shielding film and the second lens array, the distance between the second light-shielding film and the first lens array, the first light-shielding film and the first light-shielding film, The intervals between the two light-shielding films may be substantially equal to each other.

Further, in the case of comprising two light shielding films, according to the present invention, the first lens array and the second light shielding film are respectively formed on two surfaces of the substrate, and the second lens array is formed. An optical device in which the first light-shielding film is formed on each of two surfaces of a substrate, and the substrates are opposed to each other on the surface on which the light-shielding film is formed and fixed with a transparent spacer plate interposed therebetween. I will provide a.

Further, according to the present invention, the first lens array and the second lens array are respectively formed on a substrate, and the respective lenses of the first and second lens arrays are located on the substrate surface. Provided is an optical device having a light-shielding property on the surface excluding the portion to be covered.

Further, the lenses of the first and second lens arrays are aligned at equal intervals, and the width of at least one of the lenses of the first and second lens arrays in the alignment direction is between the lenses. It may be set to be an even multiple of the product of the pitch and the reduction ratio of the reduced real image formed by each lens, and the lenses of the first and second lens arrays have a rectangular shape. It may be configured as follows.

Here, as the material of the light-shielding film, Cr, T
A metal such as i can be used, but in order to further provide an antireflection effect, a dielectric such as Cr ₂ O ₃ and any one of these may be stacked to form a multilayer film. Also,
Black paint or the like can also be used. As each of the lenses forming the first lens array and the second lens array, a refraction type optical lens which is normally used may be used, but a Fresnel lens is particularly used in view of downsizing. preferable. Further, a binary lens having a plurality of stepped convex surfaces on its surface may be used. It is preferable to use quartz as the material of the lens, but in addition,
Acrylic resin, polymethylmethacrylate resin (PMM
An optical synthetic resin such as A resin) can be used.
Further, each lens of the second lens array may be formed by decentering the center of its shape and the optical center, and the optical center is located on the edge of the lens shape. Alternatively, it may be located outside thereof.

According to the present invention, the first lens array and the second lens array are composed of two rows of lens groups aligned at the same pitch, and real images obtained from the respective lens groups are combined to form one real image. And an optical device configured to form the optical device.

The present invention also includes an optical device as described above, a light irradiation device, and an image sensor for photoelectrically exchanging a real image formed by light emitted from the light irradiation device and passing through the optical device. An image reading device characterized by being provided. Here, the light irradiation device comprises a light source, a light source, and a light guide device that is disposed between the image to be read and the optical device and guides and irradiates light from the light source to the image. You may comprise.

Further, the light guide device is made of a light-transmissive substance, and has a light receiving port for receiving the light from the light source into the substance, and the light from the light source received by the light receiving port. A first reflector that reflects inside, a second reflector that reflects the light reflected by the first reflector inside the substance, and a light that is reflected by the second reflector are transmitted to irradiate the image. The light guide plate may be provided with an irradiation port for controlling the image and a transmission port for transmitting the reflected light reflected from the image and passing through the irradiation port to the optical device.

The present invention also provides an optical device according to claim 1, a light emitting device for emitting a desired light emitting pattern, and a light emitting pattern image formed by light emitted from the light emitting device and passing through the optical device. The present invention provides an optical printer including a photoconductor on which a latent image is formed and a printing mechanism for transferring a real image formed on the photoconductor onto a sheet.

[0027]

According to the present invention, the inverted reduced real image formed by the first lens array is arranged at a position corresponding to each lens of the first lens array so as to be an erecting equal-magnification image, for example. A second lens array composed of a plurality of lenses, arranged between the first lens array and the second lens array, and arranged to pass the light emitted from each lens of the first lens array. Since the optical device has one or a plurality of light-shielding films each having a through hole formed at a position facing the lens, it is possible to reduce the size and cost of the optical device by preventing crosstalk as much as possible. Can be provided.

Further, by constructing the optical device having only one light-shielding film, the manufacture of the optical device can be facilitated and the cost can be reduced. When the number of the light-shielding films is two, the second light-shielding film is arranged between the first light-shielding film and the first lens array, so that the crosstalk can be further reduced. it can. Further, the light shielding film is arranged at the position of the image plane of the reduced real image formed by each lens of the first lens array, or is arranged substantially in the middle of the first lens array and the second lens array. Since the optical device is configured as described above, it is possible to further reduce crosstalk.

Further, although the light-shielding film does not substantially limit the optical path from each lens of the first lens array to the corresponding lens of the second lens array,
Since each of the lenses of the lens array has a through hole having an opening width capable of substantially blocking the optical path from the corresponding lens of the second lens array to the adjacent lens, the brightness of the image formed is reduced. Can be made uniform.

Further, when the light-shielding film is composed of two, the substrate on which the first lens array and the light-shielding film are formed on different surfaces, and the light-shielding film and the second lens array are different from each other. The substrate formed on the surface is fixed with the transparent spacer plate sandwiched so that the surfaces of the both substrates on which the light shielding film is formed face each other, facilitating the manufacture of the optical device. In addition, the price can be reduced.

Further, according to the present invention, the first lens array and the second lens array are respectively formed on a substrate, and the surface of the substrate is the respective lenses of the first and second lens arrays. Since the surface excluding the position where is present has a light-shielding property, it is possible to further suppress crosstalk, and the lenses of the first and second lens arrays are arranged at equal intervals. At least one of the width in the alignment direction of each lens of the first lens array and the width in the alignment direction of each lens of the second lens array is
Since the adjustment is made to be an even multiple of the product of the pitch between the lenses and the reduction ratio of the reduced real image formed by each lens, the brightness of the image formed can be made more uniform. .

In the above optical device, by using the Fresnel lens or the binary lens as the first lens array and the second lens array, mass production becomes possible, and therefore the cost can be further reduced. be able to. When a binary lens is used, each lens of the second lens array is formed by decentering the shape center and the optical center, and each lens of the second lens array. By having the optical center of the light source be on or outside the edge of the lens shape, the light utilization efficiency can be increased and the image contrast can be improved.

Further, the first lens array and the second lens array are composed of two rows of lens groups aligned at the same pitch, and real images obtained from the respective lens groups are combined to form one real image. If you configure it to
The contrast can be kept good and the brightness of the image can be increased. Further, by using the optical device according to the present invention for an image reading device or an optical printer, it is possible to reduce the size and cost of these devices.

[0034]

1 is a cross-sectional view of a part of an image reading device 1 using an optical device 22 according to the present invention.

The image reading device 1 includes a band-shaped image sensor 12 including a CCD, an optical device 22, and
It comprises a drive mechanism (not shown), a housing, a control circuit, a signal processing circuit, and the like.

The image sensor 12 and the optical device 22 are integrally connected to each other, and a light source (not shown) for illuminating the document DM is integrally attached to them.
This constitutes a scanner that extends in the left-right direction in FIG. The scanner moves in the direction perpendicular to the paper surface of FIG. 1 to scan the surface of the document DM arranged above the optical device 22, read the image drawn on the document DM, and convert it into an electric signal. To do. At that time, the optical device 22 guides the reflected light from the document DM to the image sensor 12, and forms an erecting equal-magnification image of the image of the document DM on the image sensor 12.

The thickness L2 of the optical device 22 is, for example, about 1.
275 mm, the distance L1 between the optical device 22 and the document DM is, for example, about 1.6 mm, the optical device 22 and the image sensor 1
The distance L3 from 2 is, for example, about 1.8 mm.

Example 1 FIG. 2 shows an optical device 2 according to the present invention.
It is a figure which shows a part of 2 cross-section. The optical device 22 includes a first substrate 31, a spacer plate 35, and a second substrate 36.
Are integrally attached to each other.

The base material 32, which is the main part of the first substrate 31, is
A transparent synthetic resin such as acrylic resin or PMMA resin is formed into a thin strip plate having a thickness of about 300 μm, and a plurality of thin strips arranged in a row in the left-right direction of FIG. A first lens array 50 including lenses 51, 52, 53, ... Is formed. here,
As a lens, an optical lens (op
tical lens), Fresnel lens (Fresnel lens), a binary lens which is a thin lens having a stepped surface can be used.

FIG. 10 shows sectional views showing the shapes of various lenses. In the figure, (a) is a refraction type optical lens which is normally used. (B) is a diffractive Fresnel lens, which is an example of a diffractive optical element, and is formed by removing a portion that does not affect the wavefront conversion function from the refractive lens. (C) is a binary lens used in Examples described later, and is a lens formed by approximating the spherical surface portion of the diffractive Fresnel lens of (b) in a stepwise pattern. The efficiency of diffraction differs depending on the number of steps (levels), and the higher the number of levels, the better the efficiency. This (c) shows a 4-level binary lens.
Each lens 51, 52, 53 of the first lens array 50 ...
Have the same shape as each other, the opening diameter is 75 μm, and the focal length is 480 in the base material 32 (that is, in the synthetic resin).
μm, and the pitch between the lenses is 350 μm.

Substrate 32 with first lens array 50
Is manufactured by, for example, manufacturing a prototype by etching a glass plate, manufacturing a mold based on the master, and pouring a synthetic resin into the mold to mold the mold. As described above, by using the synthetic resin as the material of the base material 32, mass production with a mold is easy. However, it is also possible to use glass as the material of the base material 32. In that case, it is excellent in transparency,
Since the thickness of the base material 32 is small, the superiority or inferiority of the transparency does not matter so much. In addition, acrylic resin and PM are used as synthetic resin.
When MA resin is used, its refractive index is about 1.5.

A light-shielding film 33 is provided on the surface of the substrate 32 on the side where the first lens array 50 is formed, where the lenses 51, 52, 53 ... Are not formed. The light-shielding film 33 is for blocking the light from the outside and for preventing the light from being reflected inside the base material 32. It is formed by a non-reflective coating which is suppressed to a certain degree, application of black paint or printing. For example, the metal is Cr,
Cr ₂ O ₃ is used as the oxide.

On the other surface of the substrate 32 (the lower surface in FIG. 2), the second light-shielding film 34 is provided, and the above-mentioned light-shielding film 3 is formed.
The same material and method as those of No. 3 are used. The second light-shielding film 34 has a circular aperture 61 having an opening diameter of 85 μm at a position facing each of the lenses 51, 52, 53, ... In order to pass the light emitted from the lenses 51, 52, 53.
62, 63 ... Are formed.

The base material 37, which is the main part of the second substrate 36, is
The same material as that of the base material 32 is formed into a strip plate shape having a thickness of about 675 μm, and on the lower surface of FIG. 2, a plurality of lenses 81 arranged in a row in the left-right direction at equal pitches. , 82, 83 ... A second lens array 80 is formed.

Each lens 81 of the second lens array 80,
82, 83, ... Have the same shape and have an opening diameter of 2
70 μm, the focal length is 540 μm in the base material 37, and the pitch between the lenses is the above-mentioned lenses 51, 52, 5
Like 3 ... 350 μm. Second lens array 8
The base material 37 having 0 is manufactured by the same manufacturing method as the base material 32 described above.

On the lower surface of the base material 37 on which the second lens array 80 is formed, a fourth light shielding film 39 is provided in a portion where the lenses 81, 82, 83 ... Are not formed. . This light-shielding film 39 is for blocking the light from the outside and preventing the reflection of the light inside the base material 37. As with the third light-shielding film 33, a metal vapor deposition film or a black paint film is used. It is formed by coating or printing.

A first light-shielding film 38 is formed on the surface of the base material 37 (upper surface in FIG. 2) by the same method as the above-mentioned light-shielding film 39. The first light-shielding film 38 has
In order to allow the light emitted from the apertures 61, 62, 63, ... Of the second light shielding film 34 to pass therethrough, the lenses 51, 52, 5
Circular apertures 71, 72, 73 having an opening diameter of 87.5 μm are formed at positions facing 3 ...

The spacer plate 35 is made of acrylic resin or PM.
Made of transparent synthetic resin such as MA resin, the thickness is 300
It is formed in the shape of a thin strip of about μm. The first substrate 31 and the second substrate 36 are interposed via the spacer plate 35.
However, they are adhered by an adhesive and fixed integrally.

Using the optical device 22 configured as described above, as shown in FIG.
When arranged at a distance of 6 mm, the lens 51,
The inverted real image in which the image of the document DM is reduced to 1/4 by 52, 53, is formed at the position of the first light shielding film 38, that is, the positions of the apertures 71, 72, 73. At this time, the aperture diameter (87.5 μm) of the apertures 71, 72, 73, ... Is the lens pitch (350 μm).
Since it is one-fourth of that, each aperture 71, 7
The images of 350 μm in front of the lenses 51, 52, 53, ... Are cut out by 2, 73 ,.

Then, the apertures 71, 72, 73
The inverted real image formed at the position of ...
By passing through 82, 83, ..., an erect real image is formed on the image sensor 12. At this time, the distance between the lenses 81, 82, 83, ... And the image sensor 12 is 1.8 mm, and the images are magnified four times by the lenses 81, 82, 83 ,.
An erect image of the same size as that of the original document DM is formed on 2. By the apertures 71, 72, 73, ..., the respective lenses 51, 5
Since the images of 2, 53, ... Are cut out without excess or deficiency, the image of the document DM is faithfully reproduced on the image sensor 12.

In such an optical device 22, as shown in FIG. 1, the total distance (thickness) from the document DM to the image sensor 12 is 5 mm or less (L1 + L2 + L3 = about 4.
675 mm), which is a short conjugate length that cannot be obtained by the conventional optical device, and the size of the device is greatly reduced.

Next, how the optical device 22 prevents crosstalk will be described with reference to FIG.
It is a figure which shows the state of the incident light to the optical apparatus 22 in FIG.

Light RY incident on the lens 51 from the document DM
1 passes through the apertures 61 and 71, exits from the lens 81, and reaches the image sensor 12. Lens 5
The light RY2, 3, 4 incident from 2, 53, 54 is
Since it is shielded by the light shielding film 34, it does not reach the lens 81. The light RY5 incident from the lens 55 may reach the lens 81 through the apertures 64 and 73, but even in that case, the incident angle θ on the lens 81 exceeds the critical angle θc, so that the lens 81 It is totally reflected and does not exit from the lens 81, and therefore does not reach the image sensor 12. In this way, the lens 5
Taking 1 as an example, the light RY2, 3, 4, ... Entered from other than the lens 51 never reaches the image sensor 12. Therefore, crosstalk from the adjacent lenses becomes zero, and the image of the document DM can be clearly read without lowering the contrast of the image formed on the image sensor 12.

Next, the light utilization efficiency of the optical device 22 will be described. In FIG. 3, for example, the light emitted from one point PT1 on the document DM (the point PT1 corresponds to the edge portion of the image formed by the lens 53) is the point PT of the lens 53.
After entering from 2 to the point PT3 and forming a reduced intermediate image at the point PT4, the point PT5 to the point PT6 of the lens 83 is formed.
Then, the image is formed on the image sensor 12.

As described above, since all the part of the light that has entered the lens 53 that contributes to image formation enters the lens 83, the light utilization efficiency is good and the image sensor 12
The brightness of the image formed above becomes uniform. In order to establish such an optical system, it is necessary that the reduction ratio of the intermediate image is less than 1/2, and practically it is about 1/4 or less. It is desirable in terms of utilization efficiency.
As described above, the reduction ratio of the intermediate image is 1/4 in this embodiment.

As described above, the lenses 51, 52, 53
Since the first light-shielding film 38 having the apertures 71, 72, 73 with an aperture diameter that is a reduction ratio times the lens pitch is provided at the position of the image plane of the reduced inverted real image formed by. It is possible to prevent the overlap between the images formed by the individual lenses 51, 52, 53 .... However, strictly speaking, the first image is placed at the image plane position of the inverted reduced real image.
It is not necessary to provide the light-shielding film 38, and if the light-shielding film 38 is provided in the vicinity of the image plane of the inverted reduced real image, substantially the same effect can be obtained. Here, the vicinity position may be within a range of ± 100 μm from the position of the image plane of the inverted reduced real image, for example.

Further, since the second light-shielding film 34 is provided between the lenses 51, 52, 53, ... And the first light-shielding film 38, the images formed by the lenses 51, 52, 53 ,. It is possible to prevent the formation of an image in the adjacent openings of the apertures 71, 72, 73 ... Of the film 38, and to obtain an erecting equal-magnification image without crosstalk.

Even if the intermediate lens is not provided at the positions of the apertures 71, 72, 73, ...
Since the reduced intermediate images are formed at the positions 1, 72, 73, ..., The lenses 51, 52, 5 of the first lens array 50 are formed.
All of the effective portion of the light incident on 3 ... Can be guided to the lenses 81, 82, 83 ... Of the second lens array 80,
There is no reduction in light utilization efficiency.

Example 2: Next, the lenses 51, 52, 53
, And lenses 81, 82, 83, ..., An optical device 22a will be described as an example in which a binary lens, which is one form of a Fresnel lens, is used. FIG. 4 is a cross-sectional view showing a part of an optical device 22a of the present invention using a binary lens.

In FIG. 4, the light shielding films 34a, 38a, 3
3a and 39a are for blocking the light from the outside and preventing the reflection of the light inside. Lens 51a
(Lenses 51a, 52a, 53a ...) And lens 81a
(Lenses 81a, 82a, 83a ...) Are binary lenses. Of the Fresnel lenses, the diffractive Fresnel lens is an ordinary refraction type lens except that a portion that gives an optical path difference of an integral multiple of the wavelength that does not affect the focusing effect of the lens is removed. The surface shape of this diffractive Fresnel lens is approximated to a step shape. The shape of the binary lens is easy to control, and the reproducibility of the focal length is good. However, since the binary lens is a diffractive type lens, the reduction in contrast due to the non-diffracted light that is the direct light is more problematic than that due to the crosstalk.

Therefore, in order to separate the real image obtained by the lens 81a and the non-diffracted light, the center of the opening of the lens 81a and the optical center OL are largely decentered, and the optical center OL of the opening is set. It is located outside the edge. Here, the optical center of the lens 51a and the optical center of the lens 81a are arranged so as to substantially face each other as in the first embodiment. As a result, the opening of the lens 81a is
It is arranged at a position displaced from the opening of a. As a result, the real image formed by the lens 81a is formed on the image sensor 12a on the axis connecting the optical centers of the two lenses, but the non-diffracted light does not reach the image sensor 12a. The contrast of the real image is improved.

If necessary, the optical center of the lens 51a may be decentered from the center of the opening to further improve the contrast. As described above, by using the binary lens, the mold can be easily manufactured, and the cost can be further reduced by mass production. That is, it is difficult to manufacture a three-dimensional object such as a conventional rod lens array, but since the optical device 22 of the present invention is manufactured by combining planar elements, it is relatively easy to manufacture and mass production is easy. . An example of the manufacturing process of the binary lens used in the present invention will be described later.

In the above embodiment, the first substrate 31
And the second substrate 36 are produced, and these are used as the spacer plate 35.
The second light-shielding film 3 is fixed since it is fixed with an adhesive agent.
4, the first light-shielding film 38 and the like are easily formed, arranged, and positioned, and the optical device 22 is easily manufactured.
However, the structure of the substrate can be variously changed. For example, a first substrate having the first lens array 50 and the light shielding film 33 formed on one surface thereof, a second substrate having the second lens array 80 and the light shielding film 39 formed on one surface thereof, and a second substrate The light-shielding film 34 and the other substrate having the first light-shielding film 38 formed on both surfaces may be fixed by an adhesive while sandwiching two kinds of spacer plates between them.

In the above embodiment, the second light shielding film 34 is used.
Is preferably near the intermediate position between the first lens array 50 and the first light shielding film 38 as shown in FIG.
As the second light shielding film 34 moves away from the vicinity of the intermediate position, the crosstalk preventing effect decreases. Further, the constants such as the aperture diameter and the lens pitch of each lens may be determined so that there is no problem in forming an image.

In the above-described embodiment, lenses may be arranged at the positions of the apertures 71, 72, 73 ... Of the first light shielding film 38 of FIG. 2 to form a third lens array. In this case, the reduction rate of the image by the first lens array 50 can be reduced (close to 1) to increase the amount of light to be captured, and the brightness of the image can be increased. Further, by providing such a third lens array, it is possible to suppress the spread of light on the emission side. Therefore, the aperture diameters of the lenses 81, 82, 83, ... Can be reduced to facilitate their manufacture, the light utilization efficiency can be further improved, and the unevenness in image brightness can be further reduced. You can

Third Embodiment Next, an optical device 22b, which is an embodiment in which the first substrate 31, the spacer plate 35, and the second substrate 36 have substantially the same thickness, will be described. FIG. 5 is a cross-sectional view showing a part of the optical device 22b.

The thicknesses of the first substrate 31b, the spacer plate 35b, and the second substrate 36b are all 500 μm.
Each lens 51b, 52b of the first lens array 50b,
53b ... Binary lenses in which all the light-transmitting portions of the light-shielding film 33b have rectangular openings of the same shape, and the opening width is 135 μm in the column direction of the lens array and 102 μm in the orthogonal direction. The focal length is 607 μm in the base material 32b.
And the pitch between the lenses is 545 μm.

Each lens 81 of the second lens array 80b
Also, b, 82b, 83b ... Are binary lenses in which the light-transmitting portions of the light-shielding film 39b all have rectangular openings of the same shape, and the opening width is 256 μm in the column direction of the lens array and 192 μm in the orthogonal direction. The focal length and the pitch between the lenses are the first
Lenses 51b, 52b, 53 of the lens array 50b of
It is the same as b ...

The second light-shielding film 34b has lenses 51b,
In order to allow the light emitted from the lenses 52b, 53b, ... To pass through the lenses 51b, 52b, 53b, ..., Rectangular apertures 61b, 62b, 63b, ... 215 .mu.m in the column direction and 500 .mu.m in the orthogonal direction are formed. ing. Further, the first light-shielding film 38b is arranged in a column direction at a position facing each lens 51b, 52b, 53b ... In order to pass the light emitted from the apertures 61b, 62b, 63b ... Of the second light-shielding film 34b. Is 255 μm, orthogonal direction is 500 μm
m rectangular apertures 71b, 72b, 73b ... Are formed.

When the original DM is placed at a distance of 2.2 mm from the optical device 22b as shown in FIG. 1 using the optical device 22b having the above-described structure, the lens 5
The inverted real image obtained by reducing the image of the original document DM by 0.235 times by 1b, 52b, 53b, ...
8b and the second light-shielding film 34b are formed in the vicinity of an intermediate position.

The inverted real image formed near the middle of the first light-shielding film 38b and the second light-shielding film 34b further passes through the lenses 81b, 82b, 83b ... The image is formed as an erect real image on the top. At this time, the lenses 81b, 82b, 83b
The distance between the image sensor 12 and the image sensor 12 is 2.2 mm, and the image is magnified to the original size by the lenses 81b, 82b, 83b.
An erect image of the same size as the original is formed on the top.

However, the apertures 61b, 62b, 63
b and the apertures 71b, 72b, 73b, ..., The lens 8 facing each lens 51b, 52b, 53b.
Since the optical path to 1b, 82b, 83b ... is not blocked at all,
The image formed by each lens is the average value of the aperture width of the first lens 135 μm and the aperture width of the second lens 256 μm (195.5
832μ divided by the magnification of the intermediate image (0.235)
It has a width of m. Since the lens pitch is 545 μm, the images formed by the respective lenses will overlap each other in the column direction. Here, since the illuminance of the image by each lens gradually becomes darker in the peripheral portion of the image, there is little change in the illuminance in the column direction of the composite image, and the images smoothly overlap.

In particular, in the above-mentioned embodiment, the light shielding film 3
9b, each lens 81 of the second lens array 80b
b, 82b, 83b ... Aperture width in the column direction (256 μm)
However, since it is twice the product of the pitch of the lens array (545 μm) and the reduction ratio of the intermediate image (0.235), the brightness of the overlapped images becomes uniform.

Here, the fact that the brightness of the overlapped images becomes uniform will be described with reference to FIG. In FIG. 6, when the aperture width in the column direction of the lenses 81b, 82b, 83b of the second lens array 80b by the light shielding film 39b is twice the product of the pitch of the lens array and the reduction ratio of the intermediate image,
The illuminance distribution of the image formed by each lens 81b, 82b, 83b ... Is calculated. The illuminance of the image formed by each lens is high at the center and becomes lower toward the periphery. The shape of the illuminance distribution in the column direction of the image by each lens is the same as that of each lens 51b, 52 of the first lens array 50b.
Depending on the size relationship between the column-direction opening widths of b, 53b, ... And the column-direction opening widths of the lenses 81b, 82b, 83b, ... Of the second lens array 80b, there are three types of patterns shown in the drawing. It can be seen that the illuminance of the overlapping images has a constant value regardless of the position in the column direction in any case.

Thus, in order to make the illuminance of the combined image uniform in the column direction, the aperture width in the column direction of either one of the lens arrays is the product of the pitch of the lens array and the reduction ratio of the intermediate image. It can be found from the same calculation that even multiples are required.

In the above-mentioned embodiment, since each lens of the lens array has a rectangular aperture, the illuminance distribution in the column direction of the lens array and the illuminance distribution in the orthogonal direction are independently obtained. Regarding the illuminance distribution in the orthogonal direction of the columns, for each of the lenses 51b, 52b, 53b of the first lens array 50b,
The absolute value of 1/2 of the difference between the opening width (h1) in the column in the orthogonal direction and the opening width (h2) in the column in the orthogonal direction of the lenses 81b, 82b, 83b, ... Of the second lens array 80b. To
A value divided by the reduction ratio (r) of the intermediate image, that is, | h1-h
It has a uniform width of 2 | / (2r) near the center. Therefore,
In the above embodiment, | 102-192 | / (2 ×
0.235) = 191, that is, the illuminance distribution is uniform in the region of 191 μm near the center and gradually decreases outside the region.

As described above, the image of the original document DM obtained by the optical device 22b has a width of 191 μm and a uniform illuminance distribution in the column direction of the lens array. Therefore, it is possible to obtain an image with uniform brightness without uneven brightness. Further, in the above-described embodiment, the aperture width of the light-shielding film is about 40 μm larger than the width of the optical path from each lens 51b, 52b, 53b ... To the opposing lenses 81b, 82b, 83b. A tolerance of ± 20 μm can be secured for the alignment accuracy of the and.

Example 4: Next, the first lens array 5
The optical device 2 which is an example in which the 0 and the second lens array 80 are each composed of two lens rows.
2c will be described. FIG. 7 shows the lens arrays 50c and 80c that form the optical device 22c, the light shielding film 34c,
It is a figure which shows the shape and arrangement of 38c. FIG. 9 is an enlarged layout view of a part of the lens arrays 50c and 80c.

The thicknesses of the first substrate 31c, the spacer plate 35c, and the second substrate 36c are all 500 μm, as in the previous embodiment. The first lens array 50c has 2
.. and 51c-2, 52c-2, 53c-2 .. Each lens 51c-1, 52c-1, 53c-1, ...,
And 51c-2, 52c-2, 53c-2 ... Are binary lenses having rectangular openings of the same shape due to the light shielding film 33c, and the opening width is 2 in the column direction of the lens array.
62 μm and 183 μm in the orthogonal direction. The focal length is 607 μm in the base material 32b, and the pitch b1 between the lenses is 558 μm. Lens 51c-1,5
2c-1, 53c-1, ... And 51c-2, 52c-
The optical centers of 2, 53c-2, ... Align with the center of the rectangular aperture, and the center-to-center distance a1 of the two rows of lenses is also the pitch b.
It is 558 μm, which is the same as No. 1.

Each lens of the second lens array 80c is also
Two rows of lenses 81c-1, 82c-1, 83c-1, ...,
And 81c-2, 82c-2, 83c-2, ..., All of which are lens-shading films 39c and have a rectangular aperture of the same shape. The aperture width is 183 μm in the column direction of the lens array and 131 μm in the orthogonal direction. Is. The focal length and the pitch between the lenses are the same as in the first lens array. However, since the lenses of the second lens array decenter the center of the opening and the optical center,
The optical center of the lens is located at the center of the inner edge of the two rows of rectangular openings. Center-to-center distance a2 of two rows of lenses
Is 558 μm, which is the same as the pitch b2.

The second light-shielding film 34c has a lens 51c-
1, 52c-1, 53c-1, ..., And 51c-2, 5
2c-2, 53c-2, ... To pass the light emitted from 2c-2, 53c-2.
And 52c-2, 53c-1 and 53c-2, ... at a position of 275 μm in the column direction and 1000 μm in the orthogonal direction.
Rectangular apertures 61c, 62c, 63c ... Are formed.

Further, in order to pass the light emitted from the apertures 61c, 62c, 63c of the second light-shielding film 34c through the first light-shielding film 38c, each lens group: 51c-1 and 51c-2, 52c. -1 and 52c-2, 53c-1 and 5
3c-2, ... at a position facing the 3c-2, ...
Rectangular apertures 71c, 7 having an orthogonal direction of 1000 μm
2c, 73c ... Are formed.

FIG. 8 is a cross-sectional view showing a part of the above-mentioned optical device 22c. Since the optical centers of the lenses are located at the inner edges of the openings of the lenses 81c-1 and 81c-2, the non-diffracted light deviates to the outside, and the real images are equidistant from the lenses 81c-1 and 81c-2. An image is formed on the image sensor 12c at. Each lens 81c-1, 81c-2
Although the illuminance of the image formed by the lens decreases as the distance from the lens increases, the lens 81c-
By combining the two images of 1 and 81c-2, it is possible to prevent a decrease in illuminance at the intermediate position and to secure a region of uniform illuminance distribution.

Since the aperture has a slit shape, the light from the lens 51c-1 (51c-2) enters the lens 81c-2 (81c-1) to form an unnecessary image. Forms an image at a position sufficiently distant from the image sensor 12c, so that it does not affect the contrast.

In the above-described embodiment, the shapes, dimensions, positions, materials, numbers, etc. of the first lens array 50, the first light-shielding film 38, the second light-shielding film 34, the second lens array 80, etc. The overall configuration, shape, size, etc. of the first substrate 31, the second substrate 36, the spacer plate 35, or the optical device 22 or the image reading device 1 can be variously changed in accordance with the spirit of the present invention.

Embodiment 5: Further, the light shielding film is the first light shielding film 3
8 and the second light-shielding film 34, the single layer of light-shielding film can be used instead. 11 and 12 show an example of an optical device having one light-shielding film. FIG. 11 shows a first substrate 31 and a second substrate 36.
Is an example in which the thicknesses of the optical devices 22a and 22b are made substantially equal, and a part of the optical device 22b is shown in cross section. In FIG. 11, the thicknesses of the first substrate 31b and the second substrate 36b are all 500 μm.

Each lens 51 of the first lens ray 50b
b, 52b, 53b ... Are binary lenses in which the light-transmitting portions of the light-shielding film 33b all have rectangular openings of the same shape, and the opening width is 100 μm in the column direction of the lens array and 75 μm in the orthogonal direction. The focal length is 429 μm in the base material 32b, and the pitch between the lenses is 550 μm.

Each lens 81 of the second lens array 80b
Also, b, 82b, 83b ... Are binary lenses in which the light transmitting portions of the light shielding film 39b all have rectangular openings of the same shape, and the opening width is 181 μm in the column direction of the lens array and 138 μm in the orthogonal direction. The focal length and the pitch between the lenses are the first
Lenses 51b, 52b, 53 of the lens array 50b of
It is the same as b ...

The first light-shielding film 38b has lenses 51b,
In order to pass the light emitted from the light emitting elements 52b, 53b, ..., Rectangular apertures 71b, 72b, 73b ... Which are 180 .mu.m in the column direction and 500 .mu.m in the orthogonal direction are formed at positions facing the lenses 51b, 52b, 53b. ing.

When the original DM is placed at a distance of 2.1 mm from the optical device 22b as shown in FIG.
By 1b, 52b, 53b ..., an inverted real image obtained by reducing the image of the original document DM by 0.165 times is formed at a position near the middle of the first lens array 50b and the second lens array 80b. Become.

The inverted reduced real image formed in the vicinity of the middle of the first lens array 50b and the second lens array 80b is further reflected by the lenses 81b, 82b, 8b.
By passing through 3b ...
The image is formed as an erect real image on the top. At this time, the lens 81
The distance between b, 82b, 83b ... And the image sensor 12 is 2.1 mm, and the lenses 81b, 82b, 83b.
Since the image is enlarged to the original size by the above, an erect image of the same size as the original DM is eventually formed on the image sensor 12.

However, the apertures 71b, 72b, 73
b does not block the optical paths from the lenses 51b, 52b, 53b, ... To the opposing lenses 81b, 82b, 83b .., the image formed by each lens has an aperture width of 1 for the first lens.
It has a width of 852 μm obtained by dividing the average value (140.5 μm) of 00 μm and the aperture width 181 μm of the second lens by the magnification (0.165) of the intermediate image. Lens pitch is 550μ
Therefore, the images formed by the respective lenses overlap each other in the column direction. Here, the illuminance of the image by each lens is
Since it gradually becomes darker in the peripheral portion of the image, the illuminance change in the column direction of the combined image is small, and the images smoothly overlap.

In particular, also in this embodiment, the light shielding film 39
b, each lens 81 of the second lens array 80b
Since the aperture widths in the column direction of b, 82b, 83b ... Are twice the product of the pitch of the lens array and the reduction ratio of the intermediate image, the brightness of the overlapped images becomes uniform.

FIG. 12 shows an optical device having a configuration in which the second light shielding film is removed from the optical device described in FIG. In this embodiment, the first lens array 50 is formed on the upper surface of the first substrate 32, the second lens array 80 is formed on the lower surface of the second substrate 37, and the first light shielding film is formed on the upper surface. 38 is formed. First substrate 31
The total thickness of the optical device including the second substrate 32 and the second substrate 32 can be about 1.35 mm. Therefore, the optical device of the present invention can be further downsized.

Here, the lenses 51, 52, 53, ... Of the first lens array 50 have an aperture diameter of 100 μm and a focal length of 360 μm, and the lenses 81, 82, 83, ... The aperture diameter is 325 μm, the focal length is 720 μm, and the pitch between each lens is 50.
It is 0 μm. In addition, the aperture 7 of the first light shielding film 38
Are located at positions facing the respective lenses 51, 52, 53, and have an opening diameter of 125 μm.

By using the optical device constructed as described above,
When the original document DM is arranged at a distance of 1.2 mm from the optical device, the inverted real image reduced to a quarter of the image of the original document DM is located near the first light shielding film 38, that is, the aperture 71. , 72, 73, ... In the case of this embodiment, each lens of the second lens array further forms an erect image of the same size as the original DM on the image sensor 12 at a position 2.4 mm away from the lower surface of the second substrate. To be done.

When the optical device is composed of one light-shielding film as described above, either the crosstalk prevention effect or the light utilization efficiency is sacrificed, but it can be constructed with only two substrates, so that the cost is low. It is advantageous for the conversion.

Although the above-mentioned embodiment shows the case where one or two light-shielding films are formed on the surface having no lens,
The present invention is not limited to this, and the optical device may be configured using three or more light shielding films. In this case, it is disadvantageous in terms of downsizing, but it is advantageous in terms of preventing crosstalk and improving light utilization efficiency.

Sixth Embodiment: (Binary Lens and Light Shielding Film Making Step) Next, the step of making a binary lens used in the present invention will be described with reference to FIGS. 13, 14, 15 and 16. Steps 1) to 16) are steps for forming a lens, and steps 17) to 27) are steps for forming a light shielding film.

1) First, the substrate for forming the lens and the light-shielding film is washed with a commonly used washing liquid. Here, although the drawing shows a cross-sectional view of the substrate, a disk-shaped quartz substrate having a diameter of 76 mm is used as the substrate. From this quartz substrate, a plurality of binary lenses arranged in a row are formed by a predetermined number of rows.

2) Since the quartz substrate is transparent, titanium (Ti) as a metal for recognizing the position of the surface of the substrate is vapor-deposited on one surface to a thickness of 500Å. 3) A reference point, that is, a marker for determining the positions of the lens and the light shielding film to be formed is formed on a part of the edge of the substrate by etching. The drawings used to describe the following steps are enlarged views showing only a part of one binary lens.

4) In order to form a lens pattern on the quartz substrate, resist coating, pre-baking and exposure are performed in this order. As the resist, for example, THMR-ip3000-15CP manufactured by Tokyo Ohka can be used. The resist coating step is performed by rotating the substrate at a speed of 4000 rpm. Pre-baking process, the substrate at 90 ℃
Is maintained for 90 seconds, and the resist is dried by this. In the next exposure step, reduction projection exposure is performed for 400 msec using a mask plate having a desired lens pattern.

5) In order to remove the resist at the exposed position, the steps of peb, developing and post-baking are performed in this order. In the peb process, the substrate is kept at 110 ° C. for 90 seconds. In the developing step, the substrate is developed for 60 seconds using, for example, NMD-W, which is a developer manufactured by Tokyo Ohka, and the resist is removed. In the post-baking step, the substrate is kept at 120 ° C. for 20 minutes to fix the remaining resist.

6) The quartz surface at the position where the resist is removed is removed by RIE (Reactive Ion Eching). In this RIE step, while supplying 100 sccm of CF ₄ gas into the vacuum chamber, a plasma discharge of 150 w was performed for 12 hours.
It is done for a minute. 7) The substrate is washed to remove the resist remaining except the quartz removal portion. 8) Since the marker is used also in the next step, a resist for protecting the marker is formed. That is, a protective resist coating step and a baking step (90 ° C., 20 minutes) are performed.

9) Titanium (Ti) other than the marker portion is
It is removed by etching (5 minutes) as in the marker forming step. The above 1) to 9) are the first lens forming step, and by performing the following 10) to 16), the surface shape of the lens for the second time is further formed. 10) In the same manner as 2) described above, Ti vapor deposition is performed on the substrate surface, and cleaning is performed to remove the protective resist on the marker portion. 11) The same step as 4) above is performed using another mask plate. As this other mask plate, one having a pattern in which a position where quartz is desired to be removed deeper is exposed is used. The conditions of each step may be the same as in 4).

12) The same step (peb, phenomenon, post-baking) as 5) above is performed. 13) Perform the RIE process for 20 minutes in the same manner as 6) above. 14) In the same manner as 7) above, cleaning for removing the resist is performed. 15) Similar to the above 8), the step of protecting the marker (application of protective resist / baking) is performed.

16) The step of removing titanium (Ti) is performed in the same manner as 9) above. As a result, a binary lens having a stepped surface is formed as shown in the figure. here,
When a green light emitting LED is used as the light source of the image reading device, the height of this binary lens, that is, the depth of scraping the surface of the quartz substrate is 0.8 μm, and the width of the peak of the outermost binary lens is It is set to about 0.4 μm. The drawing shown in the step 16) is an enlarged view showing only the two outermost peaks of the binary lens, and one binary lens has a plurality of such peaks as shown in FIG. Formed by. Therefore, although not shown,
By the steps 1) to 16), a plurality of binary lenses are formed on one quartz substrate.

In the steps 1) to 16), an example of forming the surface of a 4-level binary lens having 4 steps by two lens forming steps is shown. When forming, the number of lens forming steps may be increased.

Next, FIGS. 15 and 16 show steps 17) to 28) of forming a light shielding film. Here, 17) to 21) is a step of forming a light-shielding film (for example, 33c and 39c in FIG. 7) on the surface side on which the binary lens has been formed, and 22) to 27) does not form a binary lens. This is a step of forming a light shielding film (for example, 34c and 38c in FIG. 7) on the side surface. Further, the cross-sectional view of the quartz substrate shown in FIG.
FIG. 6 is a diagram of a substrate showing three binary lenses.

17) First, vapor deposition of a light shielding film and cleaning of the surface are performed on the surface of the substrate on which the lens is formed. here,
The light-shielding film is composed of two layers of a 500 Å Cr ₂ O ₃ layer and a 1500 Å Ti formed thereon. The Cr ₂ O ₃ layer contributes to absorption of reflected light generated inside the quartz substrate, and the Ti layer is a layer for shielding incident light on the substrate.
The vapor deposition is performed in the same manner as in 2) above, and the cleaning is performed in the same manner as in 1) above.

18) Next, similar to the above 4), the resist coating step and the pre-baking step are performed in this order to coat the surface with the resist. 19) Further, similarly to the above 4) and 5), each process of exposure, peb, development and post-baking is performed under the same conditions, and the resist in the lens portion is removed. 20) Light-shielding film exposed on the glass surface, that is, Cr ₂
The O ₃ layer and the Ti layer are removed by wet etching. Wet etching is performed by immersing the substrate in a Ti etchant for 15 minutes and in a Cr ₂ O ₃ etchant for 1 minute.

21) Thereafter, the remaining resist is removed by using acetone. Through the above steps, the light shielding film (33c, 39c in FIG. 7) is formed on the surface on the side where the piny lens is formed.
c) is formed. 22) Thereafter, by the steps up to 27), the light-shielding film (34c, 38c in FIG. 7) and the apertures (61c-6) are formed on the other surface (aperture surface) where the piny lens is not formed.
6c, 71c to 76c) are formed. First, here, in order to form a window for confirming the marker formed in 3) above through the substrate, resist is applied only to a part of the upper portion of the marker. That is, the protective resist coating and baking steps are performed.

23) In the same manner as in 17) above, a light-shielding film is deposited and washed on the aperture surface. Here, the light shielding film is 50
0Å Cr ₂ O ₃ layer, 1500Å Cr layer, 500Å
Is formed from _three layers of Cr ₂ O ₃ layer. 24) As in the above 18), the steps of resist coating and pre-baking are performed. Here, ONPR830-10CP manufactured by Tokyo Ohka Co., Ltd. is used as the resist, and the coating is performed at a rotation speed of the substrate of 5000 rpm. Prebaked at 90 ° C
It is performed under the condition of leaving for 30 minutes.

25) Similar to the above 19), the steps of exposure, development and post-baking are performed in this order. Where the exposure is 1
Unlike 9), contact exposure is preferable. The exposure conditions are 3.0 seconds, the development conditions are 80 seconds, and the post-baking conditions are 120 ° C. and 30 minutes. 26) By the above development, wet etching is performed by immersing in a Cr etchant for 5 minutes to remove the light-shielding film in the exposed portion.

27) Finally, the remaining resist is removed in the same manner as 21) above. As described above, the light shielding film (34c, 38c in FIG. 7) on the aperture surface is formed. 28) The quartz substrate completed by the above 1) to 27) is the first and second quartz substrates 31 and 36 shown in FIG.
Used as the substrates 31c and 36c. Further, the two completed substrates and the spacer are bonded together with an adhesive, whereby the optical device used in the present invention shown in FIG. 2 or FIG. 7 is produced.

As described above, an optical device using a binary lens is manufactured. However, since it can be manufactured by the same steps as the semiconductor process when manufacturing an LSI, mass production is possible, facilitating manufacturing, and reducing manufacturing cost. The price can be increased. Further, since the lens and the light-shielding film are integrally formed, it is possible to improve the positional accuracy as compared with the case where the separately prepared lens and the light-shielding film are bonded together, and therefore, the occurrence rate of defective products can be suppressed. .

Embodiment 7: Next, an embodiment to which the optical device of the present invention is applied will be described. FIG. 17 shows an image scanner which is an application example of the image reading apparatus.

FIG. 18 is an enlarged side sectional view of the main part of FIG. The image reading apparatus 101 includes a light source 104 provided above the original 108 for irradiating the original 108 to be read with light, and two lens arrays 109 which are provided above the original 108 and overlap each other. The optical device 107 that collects the reflected light from the original 108
The one-dimensional image sensor 105, which is provided above the optical device 107 and photoelectrically converts the brightness of a real image obtained on the light receiving surface 106 by the optical device 107, and the original document 10.
8 between the light source 104 and the optical device 107,
A light guide plate 103 for guiding and irradiating the light from the light source 104 to the original 108 is provided.

As the optical device 107, for example, the optical device of the present invention shown in FIGS. 2 and 7 can be used.
The lens array 109 is an array of the above-mentioned binary lenses arranged in a line. The light source 104, the lens array 109, the light receiving surface 106 of the image sensor, and the light guide plate 103 described above each have a depth in the array direction of the lens array 109 (a depth direction of the paper surface), which is approximately the same as the required document reading width. are doing.

An image is scanned by moving the image reading device 101 in the direction perpendicular to the array direction of the lens array 109. At this time, a control unit (not shown)
Image sensor 1 according to the clock given from
Reference numeral 05 photoelectrically converts the reflected light from the original 108 and stores the photoelectrically converted electric signal in a storage unit (not shown) to perform reading.

FIG. 19 is an enlarged side sectional view for explaining the structure of the light guide plate. The light guide plate 103 has a parallelogram shape in a side view, and is long and flat in the depth direction of the paper (thickness 1.
It is made of transparent parallelepiped-shaped transparent plastic material or glass and has a structure in which a reflector is provided inward on each surface.

This light guide plate 103 has a light source 10 on its upper surface.
A light receiving port 115 for receiving light from the light source 104 is provided at a portion immediately below the light source 104 and a portion directly below the optical device 107, respectively.
And a transmission opening 117 for transmitting the reflected light from the document 108 to the optical device 107. Light receiving port 115
The first reflector 111 that reflects the light from the light source 104 is provided on the side surface adjacent to, and the light reflected by the first reflector 111 is reflected on the parallel side surface of the first reflector 111. A second reflector 112 that irradiates the original 108 is provided.

On the lower surface of the light guide plate 103, an irradiation opening 116 for transmitting the light reflected by the second reflector 112 and irradiating the original 108 is provided directly below the transmission opening 117. A portion other than the light receiving port 115 and the transmitting port 117 on the upper surface is provided with a third reflecting body 113 so that the light reflected by the first reflecting body 111 does not leak to the outside. The portion is provided with a fourth reflector 114 so that the light reflected by the first reflector 111 does not leak to the outside. In addition, the first reflector 111 and the second reflector 11
The side surface not provided with 2 is also provided with a reflector so that the light reflected by the first reflector 111 does not leak to the outside.

The light from the light source 104 is received by the light receiving port 115 provided on the upper surface of the light guide plate 103, reflected by the first and second reflectors 111 and 112, and the path thereof is laterally displaced and guided. Irradiation port 11 provided on the lower surface of light plate 103
The surface of the manuscript 108 is irradiated with light from 6. The light reflected on the surface of the original document 108 has an irradiation opening 116 and a transmission opening 117 provided above the irradiation opening 116 (the upper surface of the light guide plate 103).
And is incident on the optical device 107 provided above the transmission opening 117.

In the optical system of the image reading apparatus having such a structure, since the optical apparatus of the present invention as described above is used, the thickness can be greatly reduced and the image forming distance (original 108- The distance between the image sensor light receiving surfaces 106) can be set to 7.1 mm or less. In particular,
The distance from the document 108 to the optical device 107 is 3.1 mm
(The thickness of the protective glass on the original reading surface is 1.0 mm and the thickness of the light guide plate 103 is 1.8 mm), the thickness of the optical device 107 is 1.5 mm, the optical device 107 to the image sensor 1
The distance to 05 is 2.5 mm (including the thickness of the protective glass of the image sensor of 1.0 mm). Further, in general, when the image forming distance is shortened, it is difficult to secure the position of the light source capable of directly irradiating the original with light, but the light guide plate 103 as shown in FIG. Since the path of the irradiation light from the light source 104 is laterally displaced by being provided between them, it is possible to guide the illumination light onto the original 108 while maintaining a short imaging distance.

In the above-described embodiments, the case where the optical device of the present invention is applied to the image reading device is shown, but it is also possible to apply the optical device to an image forming device such as an image forming system of an LED printer. . In this case, by disposing the LED array at the position of the document DM and disposing the photosensitive drum at the position of the image sensor 12, an image corresponding to the lighting pattern of the LED array can be formed on the photosensitive drum. As described above, even when the optical device 22 is applied to an image forming apparatus, it is possible to realize a small-sized and low-priced device with low crosstalk.

FIG. 20 shows an example in which the optical device of the present invention is used in an image forming apparatus of an LED optical printer. As shown in the figure, the LED optical printer exposes a cassette for storing paper, a transfer device, a fixing device, a stacker, a photosensitive drum, a developing device, a charger, a cleaning device and an erasing lamp, and a light emission pattern image to be printed. It is composed of an optical print head (including an LED array and an imaging lens) for forming on a drum. By using the optical device of the present invention for the image forming lens of the optical print head, the optical print head can be thinned and the printer can be downsized. A liquid crystal shutter may be used instead of the LED array. In the above-described embodiment, the case has been described in which an erect image of the object upright is obtained.
It is also possible to change the magnification of the second lens array so as to obtain an erect reduced image smaller than the equi-magnified image or a large erect enlarged image larger than the equal magnification image.

[0128]

According to the present invention, the first lens array including a plurality of lenses forming a reduced real image inverted from the object and the reduced real image are magnified at a predetermined magnification to form an erect image. A second lens array having a plurality of lenses arranged in such a manner, and a light-shielding film having a through hole formed between the lens arrays for allowing light emitted from each lens of the first lens array to pass therethrough. Therefore, it is possible to provide an optical device which can prevent crosstalk as much as possible, and can be reduced in size and price.

Further, by constructing the optical device provided with only one light-shielding film, the manufacturing of the optical device can be facilitated and the cost can be reduced. When the number of the light-shielding films is two, the second light-shielding film is arranged between the first light-shielding film and the first lens array, so that the crosstalk can be further reduced. it can.

When the light-shielding film is composed of two, the first
And a substrate on which the first light-shielding film and the second lens array are formed on different surfaces, and a substrate on which the lens array and the second light-shielding film are formed on different surfaces, respectively. Since the transparent spacer plates are sandwiched so that the surfaces on which the light-shielding film is formed face each other, they are fixed.
The manufacture of the optical device can be facilitated and the cost can be reduced.

Further, by using the optical device according to the present invention in an image reading device or an image forming device, it is possible to reduce the size and cost of these devices.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a part of an image reading apparatus using an optical device according to the present invention.

FIG. 2 is a cross-sectional view showing a part of an optical device according to the present invention.

FIG. 3 is a diagram showing a state of incident light on an optical device according to the present invention.

FIG. 4 is a cross-sectional view showing a part of an optical device of the present invention using a binary lens.

FIG. 5 is a cross-sectional view showing a part of an optical device of another configuration example according to the present invention.

6 is a diagram showing an illuminance distribution of an image formed by the optical device of FIG.

FIG. 7 is a diagram showing a configuration example of still another optical device according to the present invention.

8 is a cross-sectional view showing a part of the optical device of FIG.

FIG. 9 is a lens array (50c, 80c) shown in FIG.
It is an enlarged layout drawing of a part of.

FIG. 10 is a cross-sectional view showing the shapes of various lenses.

FIG. 11 is a diagram showing a configuration of an example in which the optical device according to the present invention has one light shielding film.

FIG. 12 is a diagram showing a configuration of an example in which the optical device according to the present invention has one light-shielding film.

FIG. 13 is a diagram showing a production process of a binary lens used in the optical device of the present invention.

FIG. 14 is a diagram showing a manufacturing process of a binary lens used in the optical device of the present invention.

FIG. 15 is a diagram showing a process of forming a light shielding film of the optical device of the present invention.

FIG. 16 is a diagram showing a step of forming a light shielding film of the optical device of the present invention.

FIG. 17 is a diagram showing a configuration of an image scanner which is an application example of the present invention.

FIG. 18 is an enlarged view of a main part of FIG.

FIG. 19 is an enlarged side sectional view of the light guide plate of FIG.

FIG. 20 is a diagram showing a configuration of an optical printer using the present invention.

FIG. 21 is a diagram showing a configuration of an optical device using a conventional microlens array.

[Explanation of symbols]

 22 Optical Device 31 First Substrate 33 Light-shielding Film 34 Second Light-shielding Film 35 Spacer Plate 36 Second Substrate 38 First Light-shielding Film 39 Light-shielding Film 50 First Lens Array 51, 52, 53 ... Lenses 61, 62 .63 ... Aperture (through hole) 71, 72, 73 ... Aperture (through hole) 80 Second lens array 81, 82, 83 ... Lens

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical display location B41J 2/455 G06T 1/00 H04N 1/036 A (72) Inventor Fumitaka Abe Kamitadanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Address 1015 within Fujitsu Limited

Claims (22)

[Claims] 1. A first lens array including a plurality of lenses forming a reduced real image that is inverted with respect to an object; and the first lens array for enlarging the reduced real image at a predetermined magnification to form an erect image. A second lens array composed of a plurality of lenses arranged at positions corresponding to the respective lenses of the first lens array; and the first lens array arranged between the first lens array and the second lens array. An optical device comprising one or a plurality of light-shielding films each having a through hole formed at a position facing each lens so as to allow light emitted from each lens of the array to pass therethrough. 2. The light shielding film is composed of one light shielding film,
The optical device according to claim 1, wherein the optical device is arranged at a position of an image plane of a reduced real image formed by each lens of the first lens array. 3. The light-shielding film comprises one light-shielding film,
The optical device according to claim 1, wherein the optical device is arranged substantially at an intermediate position between the first lens array and the second lens array. 4. The light-shielding film does not substantially limit the optical path from each lens of the first lens array to the corresponding lens of the second lens array, but each lens of the first lens array. 4. The optical device according to claim 3, wherein the optical device has a through hole having an opening width capable of substantially blocking an optical path from a corresponding lens of the second lens array to an adjacent lens of the second lens array. 5. The first lens array and one light-shielding film are formed on two surfaces of a first substrate respectively, and the second lens array is formed on one surface of a second substrate. The surface of the first substrate on which the light shielding film is formed and the second substrate of the second substrate.
The optical device according to claim 2, 3 or 4, wherein the optical device is fixed so as to face a surface on which the lens array is not formed. 6. The light shielding film comprises a first light shielding film and a second light shielding film, and the second light shielding film is arranged between the first light shielding film and the first lens array. The optical device according to claim 1, wherein 7. The optical device according to claim 6, wherein the first light-shielding film is arranged at a position of an image plane of a reduced real image formed by each lens of the first lens array. 8. A distance between the first light shielding film and the second lens array, a distance between the second light shielding film and the first lens array, and the first light shielding film and the second lens array. 7. The optical device according to claim 6, wherein the light-shielding film and the light-shielding film have a substantially equal interval. 9. The first light-shielding film and the second light-shielding film are formed from each lens of the first lens array to the second light-shielding film.
Does not substantially limit the optical path to the corresponding lens of the second lens array, but substantially blocks the optical path from each lens of the first lens array to an adjacent lens of the corresponding lens of the second lens array. 9. The optical device according to claim 8, wherein each of the through holes has such an opening width. 10. The first lens array and the second light-shielding film are respectively formed on two surfaces of a first substrate, and the second lens array and the first light-shielding film are second layers. Formed on each of two surfaces of the substrate, the first substrate and the second substrate are opposed to each other on the surface on which the light shielding film is formed, and are fixed with a transparent spacer plate sandwiched therebetween. The optical device according to claim 6, 7, 8 or 9. 11. The first lens array and the second lens array are formed on a surface of a substrate, respectively.
The optical device according to claim 1, wherein the substrate surface portion where each lens of the second lens array does not exist has a light shielding property. 12. The lenses of the first and second lens arrays are aligned at equal intervals, and the width of each lens of at least one of the first lens array and the second lens array in the alignment direction is , The pitch between each lens and the reduction ratio of the reduced real image formed by each lens are set to be even multiples.
The optical device described. 13. The optical device according to claim 12, wherein each of the lenses of the first and second lens arrays has a rectangular shape. 14. The first lens array and the second lens array.
14. The optical device according to claim 1, wherein each lens of the lens array is a Fresnel lens. 15. The optical device according to claim 14, wherein the Fresnel lens is constituted by a binary lens having a plurality of stepped convex surfaces on the surface. 16. The optical device according to claim 15, wherein each lens of the second lens array is formed by decentering the center of its shape and the optical center. 17. The optical device of claim 16, wherein the optical center of each lens of the second lens array is on or outside the edge of the lens shape. 18. The first lens array and the second lens array are composed of two rows of lens groups aligned at the same pitch, and real images obtained from the respective lens groups are combined to form one real image. The optical device according to claim 17, wherein the optical device is configured to: 19. An optical device according to any one of claims 1 to 18, a light irradiation device, and a real image formed by light emitted from the light irradiation device and passing through the optical device is photoelectrically exchanged. An image reading device comprising an image sensor. 20. The light irradiation device comprises a light source and a light guide device which is disposed between the image to be read and the optical device and guides and irradiates the light from the light source to the image. 20. The image reading device according to claim 19, wherein 21. The light guide device is made of a light-transmitting substance, and has a light receiving port for receiving the light from the light source into the substance, and the light from the light source received by the light receiving port. A first reflector that reflects inside, a second reflector that reflects the light reflected by the first reflector inside the substance, and a light that is reflected by the second reflector are transmitted to irradiate the image. 21. The image reading apparatus according to claim 20, further comprising: a light guide plate having an irradiation opening for transmitting light, and a transmission opening for transmitting reflected light reflected from the image and passing through the irradiation opening to the optical device. . 22. The optical device according to any one of claims 1 to 18, a light irradiation device for irradiating a desired light emission pattern, and light emitted from the light irradiation device and passing through the optical device are formed. An image forming apparatus comprising: a photoconductor on which a latent image is formed by a light emission pattern image.