JP2015118357A - Lens array optical system, image forming device having the same, and image reading device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lens array optical system which can prevent itself from blocking desired image light rays and generating unwanted ghost light.SOLUTION: A lens array optical system comprises a first lens array which includes a plurality of lenses arrayed in a first direction and forms an intermediate image of an object in a first cross-section parallel to the first direction and a direction of optical axes of the plurality of lenses, a second lens array which includes a plurality of lenses arrayed in the first direction and re-forms an intermediate image of the object in the first cross-section, a light shield located between optical axes of each pair of adjacent lenses of the first and second lens arrays. Each of the first and second lens arrays has a light scattering or absorptive part provided between each pair of adjacent lenses, each of the light scattering or absorptive part having a width in the first direction that is greater than a width of each light shield in the first direction.

Description

  The present invention relates to a lens array optical system, and is suitable, for example, for a lens array optical system used in an image forming apparatus or an image reading apparatus.

  In recent years, an image forming apparatus and an image reading apparatus using a lens array optical system composed of a small-diameter lens array have been developed. For example, an image forming apparatus and an image reading apparatus are known in which a lens array optical system is held together with an arrayed light source such as an LED, a line sensor, and the like and incorporated as a unit (optical apparatus). According to these apparatuses, it is possible to reduce the size and cost of the apparatus by using the lens array optical system.

  However, in a conventional lens array optical system, a light beam (imaging light beam) for forming a desired image on an image surface (refers to a sensor surface in an image reading device and a photosensitive surface in an image forming device). There is a problem that different unnecessary ghost light is generated.

  Patent Document 1 discloses a lens array optical system in which a light blocking member in which a light absorbing portion is formed is disposed between two lens arrays. With this configuration, light beams passing between adjacent lenses of the plurality of lenses constituting the lens array optical system are shielded, thereby preventing generation of unnecessary light (ghost light).

JP 2010-14824 A

  The lens array optical system disclosed in Patent Document 1 has an advantage that assembly is easy because the light shielding member is not fitted in the lens array. However, the relative position between the lens array and the light-shielding member may deviate from the ideal position when the environmental temperature fluctuates due to an arrangement error during assembly or because the linear expansion coefficient differs between the lens array and the light-shielding member. Can be considered. As a result, there is a problem that the light shielding member shields the imaging light beam or allows ghost light to pass therethrough.

  Accordingly, an object of the present invention is to provide a lens array optical system capable of suppressing the shielding of an imaging light beam and the generation of ghost light.

In order to achieve the above object, a lens array optical system according to one aspect of the present invention includes a plurality of lenses arranged in a first direction, and is parallel to the first direction and the optical axis direction of the plurality of lenses. A first lens array that forms an intermediate image of the object in the first cross section, and a plurality of lenses arranged in a first direction, and re-images the intermediate image of the object in the first cross section A second lens array; and a light shielding member disposed between optical axes of adjacent lenses in the first and second lens arrays, each of the first and second lens arrays being adjacent to each other. A scattering part or a light absorbing part is provided between the lenses, and the width of the scattering part or the light absorbing part in the first direction is larger than the width of the light shielding member in the first direction.
Further objects and other features of the present invention will become apparent from the preferred embodiments described below with reference to the accompanying drawings.

  According to the present invention, in a lens array optical system, an image forming light beam is blocked and ghost light is generated due to a relative positional variation between the lens array and the light shielding member due to an arrangement error during manufacturing and an environmental temperature variation, and the lens. Generation of ghost light due to the characteristic shape of the scattering portion provided therebetween can be suppressed.

1 is a schematic cross-sectional view of an optical device according to a first embodiment of the present invention, taken along (a) a main array section, (b) a sub-array section, and (c) a section perpendicular to the optical axis. FIG. 3 is a schematic cross-sectional view of a part of the main array section and the sub array section of the lens array optical system according to the first embodiment of the present invention. Typical sectional drawing in the main array section of the optical apparatus in a prior art. FIG. 3 is a schematic cross-sectional view of the lens array optical system according to the first embodiment of the present invention in a main array cross section. The expanded sectional view in the main arrangement section of the scattering part concerning a 1st embodiment of the present invention. FIG. 3 is a schematic cross-sectional view of the lens array optical system according to the first embodiment of the present invention in a main array cross section. FIG. 3 is a schematic cross-sectional view of the main array cross section of the scattering portion and the light shielding member of the lens array optical system according to the first embodiment of the present invention. The typical cross-sectional enlarged view in the main array cross section of the scattering part and light-shielding member of the lens array optical system which concerns on 1st Embodiment of this invention. The typical sectional view in the optical device concerning a 2nd embodiment of the present invention in (a) main arrangement section, (b) sub arrangement section, and (c) section perpendicular to the direction of an optical axis. FIG. 9 is a schematic cross-sectional view of a part of a main array section and a sub-array section of a lens array optical system according to a second embodiment of the present invention. The typical sectional view in the main array section of the lens array optical system concerning a 2nd embodiment of the present invention. 1 is a schematic cross-sectional view of an image forming apparatus including a lens array optical system according to an embodiment of the present invention. 1 is a schematic cross-sectional view of an image reading apparatus including a lens array optical system according to an embodiment of the present invention.

  Hereinafter, a lens array optical system (imaging optical system) according to the present invention will be described with reference to the drawings. It should be noted that the drawings shown below may be drawn at a scale different from the actual scale so that the present invention can be easily understood.

  1A, 1B, and 1C show an XY sectional view, an XZ sectional view, and a YZ sectional view of the optical device 100 according to the first embodiment of the present invention, respectively. In FIG. 1C, the black circles in the figure indicate the optical axes of the lenses constituting the lens array optical system.

  The optical device 100 includes a light source 101, a lens array optical system 102, and a photosensitive unit 103. The lens array optical system 102 includes a first lens array 107, a light shielding member 108, and a second lens array 109.

The light source 101 includes a plurality of light emitting points arranged at equal intervals along a Y direction (hereinafter, referred to as a main array direction) in which a plurality of lenses constituting the first lens array 107 are mainly arranged. ing. In this embodiment, an LED is used as each light emitting point of the light source 101. However, the present invention is not limited to this. For example, an organic EL element or the like may be used as each light emitting point.
In the lens array optical system 102, the lens arrays are arranged in a row in the Z direction (hereinafter referred to as the sub-array direction) perpendicular to the optical axis direction (X direction) and the main array direction (Y direction) of the lens array optical system 102. Has been configured. The lens array optical system 102 forms an erecting equal-magnification image in the main arrangement direction (first direction), and forms an inverted image in the sub-array direction (second direction). The arrangement pitch P of the lens array optical system 102 in the main arrangement direction is 0.76 mm.
For example, in the image forming apparatus, the photosensitive unit 103 is a photosensitive drum.

The distance between the LEDs of the light source 101 is several tens of μm, and at least several hundreds of μm is sufficiently smaller than the arrangement pitch P of the lens array optical system 102, so it can be considered that the LEDs are arranged almost continuously. it can.
Therefore, the light beam emitted from one LED in the light source 101 is condensed at one point on the photosensitive portion 103 even through a plurality of lenses arranged in the main array direction. For example, in FIG. 1A, the light beam emitted from the LED (P1) is collected on P1 ′, and the light beam emitted from the LED (P2) is collected on P2 ′. This characteristic enables exposure corresponding to light emission of the light source.

  Next, the lens array optical system 102 will be described.

  The first lens array 107 is configured such that a plurality of first lenses (hereinafter also referred to as G1) 107a, 107b,. Similarly, the second lens array 109 is configured such that a plurality of second lenses (hereinafter sometimes referred to as G2) 109a, 109b,. The lenses constituting each of the first lens array 107 and the second lens array 109 constitute a pair, and the optical axes of the lenses constituting the pair are configured to coincide with each other.

  2 shows a cross section parallel to the main array direction and the optical axis direction of a part 102a of the lens array optical system 102 (hereinafter referred to as a main array cross section), and a cross section parallel to the sub array direction and the optical axis direction (hereinafter referred to as a main array direction). Hereinafter, a schematic cross-sectional view of a sub-array cross-section) is shown.

A part 102a of the lens array optical system includes a first lens 107a, a part of the light shielding member 108, and a second lens 109a, which are arranged so as to be aligned with each other. The cross section perpendicular to the optical axis of the first lens 107a and the second lens 109a has a rectangular shape. The effective diameter of the surface on the light source 101 side (hereinafter referred to as G1R1 surface) of the first lens 107a and the surface on the photosensitive portion 103 side (hereinafter referred to as G2R2 surface) of the second lens 109a is 0.76 mm. is there. On the other hand, the effective diameter of the surface of the first lens 107a on the light shielding member 108 side (hereinafter referred to as G1R2 surface) and the surface of the second lens 109a on the light shielding member 108 side (hereinafter referred to as G2R1 surface). 0.69 mm. That is, the effective diameter is different for each surface of the lens.
A scattering portion is provided between adjacent lenses. Specifically, a scattering unit 110 is provided between the G1R2 surface of the first lens 107a and the G1R2 surface of the adjacent first lens (not shown). Similarly, the scattering portion 110 is also provided between the G2R1 surface of the second lens 109a and the G2R1 surfaces of the adjacent second lens (not shown). The light shielding member 108 of the present embodiment has a plurality of openings penetrating in the optical axis direction corresponding to the number of lenses constituting the lens array, and the light shielding wall between the adjacent openings is the optical axis of the adjacent lens. It is located in between and is arranged so as to match the scattering portion 110.
The light shielding member 108 is disposed between the optical axes of adjacent lenses in the main array section.
The light shielding member 108 may be configured to insert a light shielding plate at fixed intervals into a frame extending in the main arrangement direction and fix the light shielding plate to define a position in the main arrangement direction.
The first lenses 107a, 107b,... And the second lenses 109a, 109b,.

With respect to the main array direction, the light beam emitted from one LED in the light source 101 passes through the first lens 107 a and then forms an image on the intermediate image plane 105. Thereafter, the light passes through the second lens 109 a and forms an erecting equal-magnification image on the photosensitive portion 103.
Here, the light shielding member 108 and the scattering unit 110 play a role of reducing, for example, ghost light that passes through the first lens 107a and then travels toward the second lens 109b having a different optical axis.
The object plane (here, the light source 101) to the intermediate image plane 105 is referred to as a first optical system, and the area from the intermediate image plane 105 to the image plane (here, the photosensitive portion 103) is referred to as a second optical system. .
The first lens array forms an intermediate image of the object in the main array section, and the second lens array re-images the intermediate image of the object in the main array section.
Regarding the sub-array direction, the light beam emitted from the light source 101 passes through the first lens 107 a, passes through the second lens 109 a without being imaged on the intermediate imaging surface 105, and then enters the photosensitive portion 103. Inverted imaging.
As can be seen from FIG. 2, by adopting an inverted imaging system with respect to the sub-array direction, it is possible to increase the light capture angle in the sub-array direction while maintaining the imaging performance. And imaging performance can be achieved.

  The optical design values of the lens array optical system according to the present embodiment are as shown in Table 1 below.

Here, the intersection of each lens surface and the optical axis is the origin, and the optical axis direction is the X axis. In addition, the main arrangement direction is a Y axis and the sub arrangement direction is a Z axis. In Table 1, “E-x” means “× 10 ^−x ”.

  Each of the G1R1, G1R2, G2R1 and G2R2 surfaces is composed of an anamorphic aspheric surface, and the aspheric shape is represented by the following equation (1).

Here, C _{i, j} (i, j = 0, 1, 2,...) Is an aspheric coefficient.

  The lens array optical system disclosed in Patent Document 1 has an advantage that assembly is easy because the light shielding member is not fitted in the lens array. However, the relative position between the lens array and the light-shielding member is changed from the ideal position due to the difference in linear expansion coefficient between the lens array and the light-shielding member when an arrangement error occurs during assembly or the environmental temperature fluctuates. It is possible that it will shift. As a result, there is a possibility that the light shielding member blocks a desired imaging light beam, or conversely, unnecessary ghost light may pass therethrough.

  Specifically, this problem is illustrated by FIGS. 3 (a) and 3 (b) below.

  FIG. 3A is a schematic cross-sectional view along the main array direction in the case where the relative position between the lens array and the light shielding member of the optical device 200 according to the related art is ideal.

  When the relative position between the lens array and the light shielding member is ideal (arranged as designed), the imaging light beam K emitted from the light source 201 passes through the first lens array 207. Thereafter, the light is not blocked by the light blocking member 208, and passes through the second lens array 209 and forms an image on the photosensitive portion 103. On the other hand, ghost light G, which is a light beam that passes between the lenses of the lens array, is emitted from the light source 201, passes through the first lens array 207, and is shielded by the light shielding member 208.

  FIG. 3B is a schematic cross-sectional view along the main array direction in the case where the relative position between the lens array and the light shielding member is deviated from the ideal position in the optical device 200 according to the related art.

  As shown in FIG. 3B, when the relative position between the lens array and the light shielding member deviates from the ideal position, the imaging light beam K emitted from the light source 201 passes through the first lens array 207. After that, it can be seen that the light shielding member 208 is shielded from light. On the other hand, the ghost light G emitted from the light source 201 passes through the first lens array 207 and is not shielded by the light shielding member 208 but passes through the second lens array 209 and forms an image on the photosensitive portion 103. You can see that This leads to image degradation.

  An object of the present invention is to solve the above-described problems in the prior art. Specifically, even if the relative position between the lens array and the light shielding member is deviated from the ideal position, a lens array optical system that can prevent a desired imaged light beam from being shielded and unnecessary ghost light from being generated. The purpose is to provide.

  In order to solve the above-described problems in the prior art, in the lens array optical system according to the present invention, a scattering part or a light absorbing part is provided between the lenses of the lens array, and the width of the light shielding member is the scattering part or the light absorbing part. It is configured to be smaller than the width of. As a result, even if the relative position between the lens array and the light shielding member is deviated from the ideal position, it is possible to obtain an effect of preventing the shielding of a desired imaging light beam and the generation of unnecessary ghost light.

  Next, a specific configuration of the lens array optical system according to the present invention will be described.

  FIG. 4A is a schematic cross-sectional view along the main array direction of the lens array optical system 102 according to the first embodiment of the present invention.

Here, the width Bm of the scattering unit 110 in the main array direction is 0.17 mm, and the width Tm of the light shielding member 108 in the main array direction is 0.1 mm. That is, Bm and Tm satisfy the relationship represented by the following formula (2).
Bm> Tm (2)

  That is, the width Bm of the scattering portion 110 along the adjacent lenses is larger than the width Tm of the light shielding member 108 along the adjacent lenses.

  In the lens array optical system 102, a scattering unit 110 is provided. 4A, the light shielding member 108 is arranged so that the center position of each scattering portion 110 and the center position of the light shielding member 108 are aligned in the main array direction. As described above, when the relative positions of the lens arrays 107 and 109 and the light shielding member 108 are ideal, that is, when the relationship of the expression (2) is satisfied, the desired imaging light beam K is shielded. It is possible to prevent unnecessary ghost light G from being imaged.

  However, if the relative position between the lens array 107 or 109 and the light blocking member 108 is shifted so that the light blocking member 108 does not fall within the width of the scattering unit 110 in the main array direction in the main array direction, As shown in FIG. 3 (b), a desired imaging light beam K is shielded while unnecessary ghost light G is imaged.

Accordingly, an allowable amount ΔQm of relative positional deviation along the main array direction of the lens arrays 107 and 109 and the light shielding member 108 is expressed by the following expression (3).
ΔQm = (Bm−Tm) / 2 (3)

In this embodiment, since Bm = 0.17 mm and Tm = 0.1 mm, ΔQm = 0.035 mm.
Next, specific consideration will be given to the relative positional deviation along the main arrangement direction due to the thermal expansion difference between the lens arrays 107 and 109 and the light shielding member 108 when the environmental temperature fluctuates.

First, the linear expansion coefficient Xl in the main array direction of the first lens array 107 and the second lens array 109 is 10.0 × 10 ⁻⁵ (/ ° C.), and the linear expansion coefficient Xs in the main array direction of the light shielding member 108 is It is 9.0 × 10 ⁻⁵ (/ ° C.). These values are standard values when the lens array and the light shielding member are made of resin.
Note that the linear expansion coefficients of the first lens array 107 and the second lens array 109 in the main array direction may be different from each other.
The lens array optical system 102 is configured to expose over an A4 width (210 mm width). That is, the total length L in the main array direction of the first lens array 107, the second lens array 109, and the light shielding member 108 is 210 mm.
Furthermore, the first lens array 107, the second lens array 109, and the light shielding member 108 are positioned at the respective central portions in the main arrangement direction.
In addition, the operation compensation environment temperature of the lens array optical system 102 is 30 ° C. ± 30 ° C. This is a standard specification.

  Here, a case where the environmental temperature rises by ΔT = 30 ° C. is considered. At this time, when the center in the main array direction is used as a reference, the relative position maximum deviation ΔYmax between the lens arrays 107 and 109 and the light shielding member 108 generated at both ends of the lens array optical system 102 in the main array direction is as follows. It is expressed as equation (4).

ΔYmax = (L / 2) × ΔT × (X1-Xs)
= (210mm / 2) × 30 ℃ × (10.0 × 10 -5 /℃-9.0×10 -5 / ℃)
= 105mm × 30 ℃ × (10.0 × 10 -5 /℃-9.0×10 -5 / ℃)
= 0.0315mm (4)

  Therefore, the relative positional deviation ΔY between the lens arrays 107 and 109 and the light shielding member 108 is 0 mm at the center and 0.0315 mm at both ends. The center portion and both end portions are shifted by any value from 0 to 0.0315 mm depending on the position, and the shift amount increases as the distance from the center portion which is the reference position increases. Proportional to distance from The state of this relative position shift is shown in FIG.

From equations (3) and (4), the maximum relative displacement ΔYmax between the lens arrays 107 and 109 and the light shielding member 108 is within the range of the relative displacement ΔQm relative to the main array direction. I understand.
Therefore, it can be seen that the lens array optical system 102 can prevent a desired image-forming light beam K from being shielded and unnecessary ghost light G from being generated even if such environmental temperature fluctuations occur.

The above relationship can be generally expressed as the following formula (5).
ΔL × ΔT × ΔX ≦ ΔW / 2 (5)

  Here, ΔL is the distance from the position where the lens arrays 107 and 109 and the light shielding member 108 are positioned to the farthest position in the lens array optical system 102. In other words, the most distant position of the light shielding member 108 is the most distant position within the portion functioning as the light shielding member in the light shielding member 108. ΔT is the difference between the temperature when the lens arrays 107 and 109 and the light shielding member 108 are positioned and the temperature when the lens array optical system 102 is used. ΔX is the absolute value of the difference between the linear expansion coefficient of the lens array 107 and the linear expansion coefficient of the member that defines the positions of the light shielding members 108 in the main array direction and the sub array direction, and the linear expansion coefficient of the lens array 109. This is the larger value of the absolute values of the differences from the linear expansion coefficients of the members that define the positions of the light shielding members 108 in the main array direction and the sub array direction. ΔW is a difference (Bm−Tm) between the width Bm of the scattering portion 110 along the adjacent lenses and the width Tm of the light shielding member 108 along the adjacent lenses.

  At this time, as shown in FIG.4 (c), the light beam S which goes to the scattering part 110 increases. Although such scattered light S is not a desired imaging light beam, the scattered light 110 is scattered by the scattering unit 110, so that the intensity is sufficiently reduced at each position on the image plane.

  5A and 5B respectively show a main array direction cross-sectional view of the first lens array 107 and the scattering unit 110 and an enlarged cross-sectional view of the scattering unit 110 according to this embodiment.

As shown in FIGS. 5A and 5B, the scattering unit 110 of the present embodiment has a shape in which, for example, 17 triangular prisms having a base a = 10 μm and a height h = 10 μm are arranged. By adopting such a triangular prism configuration, it is possible to obtain an effect that the scattering portion 110 can be easily processed and the manufacturing cost can be reduced.
In addition, as a result of examination by the inventors, it was found that if the ratio of the height h to the base a of the triangular prism (aspect ratio) h / a is 0.7 or more, the scattering portion 110 exhibits a sufficient scattering effect. Therefore, in this embodiment, an example of the scattering unit 110 is illustrated using a triangular prism having an aspect ratio h / a of 1.

  In the above, the relationship between the width of the light shielding member 108 and the scattering portion 110 in the main array direction has been discussed. Next, the length of the light shielding member 108 in the optical axis direction will be discussed.

  FIG. 6 is a schematic cross-sectional view along the main array direction of the lens array optical system 102 according to the present embodiment.

  In the following description, it is assumed that the scattering unit 110 is not provided and unnecessary ghost light G is shielded by the light shielding member 108.

As shown in FIG. 6, the ghost light G emitted from a light source (not shown) passes through a lens 107a and is blocked by a light blocking member. After the ghost light G passes through the lens 107a, the point Y1 on the surface of the light shielding member 108a on the lens array 107 side, the point Y2 on the surface of the light shielding member 108a on the light shielding member 108b side, and the lens 109b. It is assumed that the point is toward the point Y3 that is the end of the.
Assuming that the distance along the main array direction from the point Y1 to the point Y3 is α and the distance along the main array direction from the point Y2 to the point Y3 is β, the ghost light is satisfied as long as the relationship of the following expression (6) is satisfied. G can be shielded by the shielding member 108.
α ≧ β (6)

If the width of the connecting portion between the lenses, for example, the lens 107a and the lens 107b in the main array direction is Bm, the width of the light shielding member 108a in the main array direction is Tm, and the lens array period of the lens arrays 107 and 109 is P, the distance β Satisfies the relationship of the following formula (7).
β = P− (Bm / 2−Tm / 2) −Tm
= P-Bm / 2-Tm / 2 (7)

  The angle formed by the straight line connecting the points Y1, Y2, and Y3 and the optical axis is θ, and the length of the light shielding member 108 in the optical axis direction is Ls. Then, a distance between an end of a certain lens of the lens array 107, for example, 107b and a lens of the lens array 109 facing the certain lens, for example, 109b (the first lens array 107 and the second lens array 109 are opposed to each other). When the maximum distance between the surfaces in the optical axis direction) is Lmax, the distance α is expressed as in the following formula (8).

α = (Lmax / 2 + Ls / 2) × tan θ
= (Lmax / 2 + Ls / 2) × (P / Lmax)
= P / 2 + (P / 2) × (Ls / Lmax) (8)

Therefore, the relationship expressed by the following equation (9) is obtained from the equations (6), (7), and (8).
Bm + Tm ≧ P × (1− (Ls / Lmax)) (9)

For example, the lens array optical system 102 according to the present embodiment is designed so that Bm is 0.17 mm, Tm is 0.10 mm, P is 0.76 mm, Ls is 1.90 mm, and Lmax is 2.33 mm. ing.
Therefore,
Bm + Tm = 0.27mm
P × (1− (Ls / Lmax)) = 0.14 mm
Thus, it can be seen that the lens array optical system 102 according to the present embodiment satisfies the relationship of Expression (9).
That is, in the lens array optical system 102 according to the present embodiment, it can be seen that the light blocking member 108 can block the ghost light G as shown in FIG.

Further, a minimum surface interval between a certain lens of the lens array 107, for example, a lens 107a facing the lens array 109, for example, 109a (light between the opposed surfaces of the first lens array 107 and the second lens array 109). Lmin is the shortest distance in the axial direction). In that case, it is preferable that the lengths Ls and Lmin of the light shielding member 108 in the optical axis direction satisfy the relationship of the following formula (10).
Ls <Lmin (10)

  That is, the length Ls of the light shielding member in the optical axis direction is preferably smaller than the minimum surface distance Lmin between a certain lens of the first lens array and a lens facing the certain lens of the second lens array. .

  By preparing the lens arrays 107 and 109 and the light shielding member 108 so as to satisfy the relationship of Expression (10), both the lens array and the light shielding member can be assembled while sliding with respect to the main arrangement direction. There is no interference with the lens array. Therefore, the lens array optical system 102 can be easily assembled. On the other hand, if the relationship of the expression (10) is not satisfied, the lens array and the light shielding member interfere with each other when the two members of the lens array and the light shielding member are slid together in the main array direction. Therefore, there is a possibility that problems such as breakage may occur.

  So far, the width of the light shielding member 108 and the scattering portion 110 in the main array direction and the length of the light shielding member 108 in the optical axis direction have been discussed. Next, an effective arrangement of the scattering portion 108 and the light shielding member 110 of the present embodiment will be discussed.

  FIG. 7 is a schematic cross-sectional view of the main array cross section of the lens array optical system 102 according to the first embodiment of the present invention including the scattering portion 110 and the light shielding member 108.

  In the following, it is assumed that the scattering portion 110 is provided with a triangular prism having an aspect ratio of 0.7 or more as shown in FIG.

  First, the triangular prism of the scattering section 110 is rounded by the edge-like ridgeline at the top and bottom, the ridgeline intentionally provided with a flat part for manufacturing advantages, and the transfer and replication processes such as injection molding. A ridgeline may be formed. For this reason, the light transmitted through the vicinity of the ridge line of the triangular prism may spread radially, and it is necessary to prevent unnecessary ghost light from being generated.

For example, as a case where the scattered light is incident on the opposite lens without being blocked, the light is transmitted through the scattering portion 110ab between the lenses 107a and 107b of the first lens array 107 in FIG. Consider the scattered light toward the lens 109a.
A light beam emitted from a light source (not shown) passes through the vicinity of the prism ridge line of the scattering section 110ab between the lens array 107 and the lenses 107a and 107b, and light is emitted radially. Such light is shielded by the short side surface and the long side surface of the light shielding member 108ab facing in the optical axis direction, straddling the lens 109a, shielded by the adjacent light shielding member, or incident again on the scattering portion and scattered. As a result, the strength is sufficiently reduced. Therefore, with such a light beam, the scattered light is shielded, so that the image is not deteriorated.

  However, there may be a case where scattered light is incident on a facing lens without being blocked. As such a case, consider scattered light that passes through the scattering portion 110bc between the lenses 107b and 107c of the first lens array 107 in FIG. 7 and travels toward the lens 109b of the second lens array 109.

A light beam emitted from a light source (not shown) passes through the vicinity of the prism ridge line of the scattering portion 110bc between the lens array 107 and the lenses 107b and 107c, and the light is emitted radially. At this time, there is a possibility that the light is not shielded by the light shielding member 108bc facing the scattering portion 110bc but is incident on the lens surface of the facing lens 109b and becomes unnecessary ghost light SG. Specifically, when the corner portion on the lens 107 side of the light shielding member 108 in FIG. 7 is Y4 and both end portions of the lens 109 are Y5 and Y6, the light shielding member 108bc facing the scattering portion 110bc is not shielded, and Y4 In the region between the line segment connecting Y5 and Y5 and the line segment connecting Y4 and Y6, the light incident on the lens surface of the lens 109b facing each other becomes unnecessary ghost light SG.
That is, it is only necessary to consider a condition in which light enters a predetermined region starting from the corner Y4 of the light shielding member 108.

The line segment connecting Y4 and Y5 has a critical angle θ1 as shown in Expression (11) with respect to the optical axis.
θ1 = tan ⁻¹ (ΔQm / ((Lmax + Ls) / 2)) (11)
Further, the line segment connecting Y4 and Y6 has a critical angle θ2 as shown in Expression (12) with respect to the optical axis.
θ2 = tan ⁻¹ ((P−ΔQm) / ((Lmax + Ls) / 2)) (12)

In this embodiment, the lens array optical system 102 has Bm of 0.17 mm, Tm of 0.10 mm, P of 0.76 mm, Ls of 1.90 mm, Lmax of 2.33 mm, and ΔQm = 0.035 mm. Designed to be
Therefore,
θ1 = 0.95 °
θ2 = 20.6 °
It is obtained.

  In order to suppress unnecessary ghost light SG generated from the vicinity of the prism ridge line of the scatterer 110, it is desirable to avoid the incidence of light rays from the scatterer 110 in the region defined by the critical angles θ1 and θ2.

  FIG. 8 shows an enlarged view of the scattering portion 110 and the light shielding member 108.

  Bm is the width of the scattering portion 110, and Tm is the width of the light shielding member 108. Further, Be is the distance between the ridgelines of the first prism from both ends in the scattering unit 110. That is, it means that the prism ridgeline formed in the scattering portion 110 is included only in the width Be.

  8A, 8B, and 8C, an effective arrangement of the scattering unit 110 and the light shielding member 108 for suppressing unnecessary ghost light SG that is incident on a lens (not shown) that faces each other will be described. .

  FIG. 8A shows a case where the width Be is larger than the width Tm of the light shielding member 108. In FIG. 8, a region indicated by a dotted line is a region where the light becomes the ghost light SG. Thus, it can be seen that various light spreading radially from the scattering unit 110 is generated, and ghost light SG is generated.

Next, FIG. 8B shows a case where the width Be is smaller than the width Tm of the light shielding member 108. In order to satisfy this condition, the triangular prism of the scattering portion 110 is formed close to the light shielding member 108. As shown in FIG. 8B, compared to the case of FIG. 8A, the light that enters the region indicated by the dotted line, that is, the light beam that becomes the ghost light SG is greatly suppressed. I understand. This is because by arranging the prism ridge line close to the light shielding member 110, the short side surface of the light shielding member 110 can receive and shield light. Thus, as a result of examination by the inventors, it was found that the ghost light SG can be effectively suppressed by making the width Be smaller than the width Tm of the light shielding member 108.
That is, the ghost light SG can be effectively suppressed by satisfying the relationship of Expression (13).
Tm ≧ Be (13)
In the present embodiment, since Tm is 0.10 mm, Be may be 0.10 mm or less.

Further, the scattering surface and the light shielding member need to satisfy the relationship represented by Expression (10) in the distance in the optical axis direction.
In the present embodiment, since the aspect ratio h / a of the triangular prism is 1, the maximum height of the triangular prism needs to be at least twice as large as ΔQm. That is, since ΔQm = 0.035 mm, the maximum height of the triangular prism needs to be 0.07 mm. In this embodiment, since Ls is 1.90 mm and Lmax is 2.33 mm, the maximum height of the triangular prism can be up to 0.215 mm. Therefore, the triangular prism can be arranged without interference in the optical axis direction.

  Further, FIG. 8C shows an arrangement relationship between the ideal scattering portion 110 and the light shielding member 108. Here, the width Be is smaller than the width Tm of the light shielding member 108, and a triangle is formed in a region surrounded by a line segment corresponding to the critical angle θ2 on both sides of the light shielding member 108 and the short side surface of the light shielding member 108. The scattering part 110 is formed so that the ridgeline of the prism enters. Thereby, the light beam Sh emitted from the scattering unit 110 is blocked by the short side surface of the light shielding member 108, and the light beam Sh that passes through the corner of the light shielding member 108 is also shielded by the long side surface of the adjacent light shielding member 108. Can do.

  In the lens array optical system according to the present embodiment, as shown in FIG. 5, the base a of the triangular prism to be formed is 10 μm. However, the present invention is not limited to this as long as the aspect ratio is maintained. By widening the prism interval, the number of prism ridge lines formed is reduced, so that light rays that pass through the vicinity of the prism ridge line of the scattering portion are also reduced, and ghost light can be suppressed.

  The lens array optical system according to the present embodiment has a configuration in which the lens array is arranged in one line in the sub-array direction. However, it is not necessary to be limited to a single row, and even if the configuration is a plurality of rows, the effect of the present invention can be obtained as long as the configuration of the present invention is provided in at least one row.

  The lens array optical system according to the present embodiment performs erecting equal-magnification imaging in the main array direction, but the present invention is not limited to this. The lens array optical system of the present embodiment performs inverted imaging in the sub-array direction, but the present invention is not limited to this.

The lens array optical system according to this embodiment includes two lens arrays and one light shielding member, but the number of lens arrays and light shielding members is not limited to this as long as the configuration of the present invention is satisfied.
For example, in addition to the first lens array that forms an intermediate image of the object in the main array section and the second lens array that re-images the intermediate image of the object in the main array section, along the intermediate image plane An embodiment in which a third lens array is provided can also be considered.

  In the lens array optical system according to the present embodiment, the lens array and the light shielding member are positioned at the center of each in the main arrangement direction. However, it is not necessary to position at each central portion, and for example, the lens array and the light shielding member may be positioned at each end as long as the configuration of the present invention is satisfied.

  In the lens array optical system according to the present embodiment, one light shielding member is provided between two lens arrays, and a scattering portion is provided on the surface of each lens array on the light shielding member side. However, the present invention need not be limited to this configuration. For example, if the configuration of the present invention is satisfied, a scattering portion may be provided on the surface opposite to the light shielding member side of each lens array, or a scattering portion may be provided only on the surface of the one lens array on the light shielding member side. May be.

  FIGS. 9A, 9B, and 9C are respectively an XY sectional view, an XZ sectional view, and a YZ sectional view of an optical device 300 according to the second embodiment of the present invention.

  The optical device 300 of the present embodiment takes the form of an image reading device. That is, the optical apparatus 300 includes a document 301 that is an object plane, a lens array optical system 302, a sensor unit 303 that is an image plane, and a document table 304. The lens array optical system 302 includes a first light shielding member 308a, a first lens array 307, a second lens array 309, and a second light shielding member 308b. That is, in this embodiment, the light shielding member 308a (308b) is disposed on the incident side or the emission side of the lens array optical system 302. In other words, the light shielding member 308a is disposed closer to the object side than the first lens array 307, and the light shielding member 308b is disposed closer to the image side than the second lens array 309. In other words, it can be said that at least one of the lens array 307 and the lens array 309 is disposed on the side not facing the other lens array 309 (307).

The lens array optical system 302 is configured by arranging a plurality of lenses with a period of 1.50 mm in the main arrangement direction. The lens array optical system 302 has two rows of lenses with an interval of 1.50 mm in the sub-array direction (Z direction) perpendicular to the optical axis direction (X direction) of the lens array optical system 302 and the main array direction (Y direction). It is configured to be a staggered array. In the following, only the lower column (the B column in FIG. 9C) of the two columns in the sub-array direction will be considered. The other column (column A in FIG. 9C) has the same configuration.
The lens array optical system 302 forms an erect image with respect to the main arrangement direction, and forms an erect image with respect to the sub arrangement direction.

  A light beam emitted from an illuminating unit (not shown) passes through the document table 304, enters the document 301, and is then reflected. The light beam reflected by the original 301 passes through the lens array optical system 302 and enters the sensor unit 303 to be detected. The light beam reflected by the document 301 is condensed at one point on the sensor unit 303 even through a plurality of lenses arranged in the main array direction. For example, in FIG. 9A, the light beam emitted from the light emitting point C is collected on C ′, and the light beam emitted from the light emitting point D is collected on D ′.

  Next, the lens array optical system 302 will be described.

  The first lens array 307 is configured such that a plurality of first lenses (hereinafter also referred to as G1) 307a, 307b,. Similarly, the second lens array 309 is configured such that a plurality of second lenses (hereinafter also referred to as G2) 309a, 309b,.

  FIG. 10 is a schematic cross-sectional view of the part 302a of the lens array optical system 302 along the main array direction and the sub array direction.

A part 302a of the lens array optical system is a part of the first light shielding member 308a, the first lens 307a, the second lens 309a, and the second light shielding member 308b arranged on the same optical axis. Contains parts. In the sub-array direction, a case where a light shielding member is arranged between two rows of lens arrays is considered. That is, in the present embodiment, only the lower row of the two rows in the sub-array direction is considered, and therefore, in the cross-sectional view in the sub-array direction, the light shielding members 308a and 308b are the upper side of the lenses 307a and 309a in the drawing. Will be placed only. All lens surfaces are circular. The effective diameter of the surface of the first lens 307a on the side of the original 301 (hereinafter referred to as G1R1 surface) and the surface of the second lens 309a on the side of the sensor unit 303 (hereinafter referred to as G2R2 surface) is 1.20 mm. is there. Similarly, the surface of the first lens 307a on the second lens 309a side (hereinafter referred to as G1R2 surface) and the surface of the second lens 309a on the first lens 307a side (hereinafter referred to as G2R1 surface). The effective diameter is also 1.20 mm. The opening cross section of all the light shielding members is circular, and the opening diameters of both surfaces of the first light shielding member 308a and both surfaces of the second light shielding member 308b are 1.30 mm.
A scattering portion 310 is provided between the G1R1 surface of the first lens 307a and the G1R1 surface of the adjacent first lens (not shown). A scattering unit 310 is also provided between the G1R2 surface of the first lens 307a and the G1R2 surface of the adjacent first lens (not shown). Similarly, a scattering portion 310 is also provided between the G2R1 surface of the second lens 309a and the G2R1 surface of the adjacent second lens (not shown). The scattering unit 310 is also provided between the G2R2 surface of the second lens 309a and the G2R2 surface of the adjacent second lens (not shown).
The first lenses 307a, 307b, ... and the second lenses 309a, 309b, ... are combined to form a lens array 307, 309, respectively.

In the main arrangement direction, the light beam reflected by the document 301 passes through the document table 304 and the first lens 307 a and then forms an image on the intermediate image plane 305. Thereafter, the light passes through the second lens 309 a and forms an erecting equal-magnification image on the sensor unit 303.
Also in the sub-array direction, the light beam reflected by the document 301 passes through the document table 304 and the first lens 307a, and then forms an image on the intermediate image plane 305 once. Thereafter, the light passes through the second lens 309 a and forms an erect image on the sensor unit 303.
Here, the light shielding members 308a and 308b and the scattering unit 310 play a role of reducing a light beam, that is, ghost light, which passes through the first lens 307a and then travels toward the second lens having a different optical axis.
Note that the object plane (here, the original 301) to the intermediate image plane 305 is referred to as a first optical system, and the area from the intermediate image plane 305 to the image plane (here, the sensor unit 303) is referred to as a second optical system. .

  The optical design values of the lens array optical system according to this embodiment are as shown in Table 2 below.

Here, the intersection of each lens surface and the optical axis is the origin, and the optical axis direction is the X axis. In addition, the main arrangement direction is a Y axis and the sub arrangement direction is a Z axis. In Table 1, “E-x” means “× 10 ^−x ”.

  The G1R1, G1R2, G2R1 and G2R2 surfaces are each composed of an anamorphic aspheric surface, and the aspheric shape is expressed by the following equation (14).

ここで、Ｒｙ、Ｒｚは曲率半径、ｋｙ、ｋｚは円錐定数、Ｂｉ、Ｃｉ（ｉ＝１，２，３，４，５・・・）は非球面係数である。

Here, Ry and Rz are curvature radii, ky and kz are conic constants, and Bi and Ci (i = 1, 2, 3, 4, 5...) Are aspheric coefficients.

  Similarly to the lens array optical system 102 according to the first embodiment, the lens array optical system 302 according to the second embodiment also includes a scattering unit or a light absorption unit between the lenses of the lens array. And the width | variety of the light shielding member is taken as the structure smaller than the width | variety of a scattering part or a light absorption part. As a result, even if the relative position between the lens array and the light shielding member is deviated from the ideal position, it is possible to obtain an effect of preventing the shielding of a desired imaging light beam and the generation of unnecessary ghost light.

  Next, a specific configuration of the lens array optical system according to the present embodiment will be described.

  FIG. 11A shows a sectional view in the main array direction of the lens array optical system 302 according to the second embodiment of the present invention. In FIG. 11A, the second light shielding member 308b is not shown.

  As in the present embodiment, when the openings of the light shielding members 308a and 308b are not rectangular, the width Bm of the scattering portion 310 in the main arrangement direction and the width Tm of the light shielding member 308a in the main arrangement direction are the lens surface and the light shielding member. Is defined by a cross section perpendicular to the sub array direction in which the distance in the main array direction is closest. That is, it is defined by a cross section perpendicular to the sub-array direction including the optical axis of the upper lens array, as indicated by a chain line L1 in FIG.

Here, the width Bm of the scattering portion 310 in the main array direction is 0.30 mm, and the width Tm of the light shielding member 308a in the main array direction is 0.10 mm. That is, Bm and Tm satisfy the relationship represented by the following formula (15).
Bm> Tm (15)

  That is, the width Bm of the scattering portion 310 between adjacent lenses is larger than the width Tm of the light shielding member 308a along the adjacent lenses.

  In the lens array optical system 302, a scattering unit 310 is provided. Then, as shown in FIG. 11A, the light shielding member 308 a is arranged so as to be aligned with the center position of each scattering portion 310. As described above, when the relative positions of the lens arrays 307 and 309 and the light shielding member 308a are ideal, if the relationship of the expression (12) is satisfied, the desired imaging light beam K is shielded or unnecessary. It is possible to prevent the ghost light G from being imaged.

  However, if the relative position between the lens array 307 or 309 and the light shielding member is shifted so that the light shielding member 308a exceeds the width of the scattering portion 310 in the main array direction, the desired imaging light beam K is shielded. Unnecessary ghost light G is imaged.

Therefore, an allowable amount ΔQm of relative positional deviation along the main array direction of the lens arrays 307 and 309 and the light shielding member 308a is expressed as the following Expression (16).
ΔQm = (Bm−Tm) /2=0.10 mm (16)

  Next, the relative positional deviation along the main array direction accompanying the expansion of the lens arrays 307 and 309 and the light shielding member 308a when the environmental temperature fluctuates will be specifically considered.

First, the linear expansion coefficient Xl in the main array direction of the first lens array 307 and the second lens array 309 is 10.0 × 10 ⁻⁵ (/ ° C.), and the linear expansion coefficient Xs in the main array direction of the light shielding member 308a is It is 9.0 × 10 ⁻⁵ (/ ° C.). These values are standard values when the lens array and the light shielding member are made of resin.
The lens array optical system 302 is configured to expose over an A4 width (210 mm width). That is, the total length L in the main array direction of the first lens array 307, the second lens array 309, and the light shielding member 308a is 210 mm.
Furthermore, the first lens array 307, the second lens array 309, and the light shielding member 308a are positioned at one end in the main arrangement direction.
In addition, the operation compensation environmental temperature of the lens array optical system 302 is 30 ° C. ± 30 ° C. This is a standard specification.

  Here, a case where the environmental temperature rises by ΔT = 30 ° C. is considered. At this time, the relative positional maximum deviation amount ΔYmax between the lens arrays 307 and 309 and the light shielding member 308a generated at the end opposite to the end positioned in the main array direction of the lens array optical system 302 is as follows. It is expressed as equation (17).

ΔYmax = L × ΔT × (X1-Xs)
= 210mm × 30 ℃ × (10.0 × 10 -5 /℃-9.0×10 -5 / ℃)
= 0.063mm (17)

  Accordingly, the relative positional deviation ΔY between the lens arrays 307 and 309 and the light shielding member 308a is 0 mm at the positioned end and 0.063 mm at the opposite end. And between the edge part on the opposite side and the edge part located, it has shifted | deviated only by the value of 0 thru | or 0.063mm according to the position, The deviation | shift amount is from the edge part located. The distance increases as the distance increases, and is proportional to the distance from the positioned end. The state of this relative position shift is shown in FIG.

From Expressions (16) and (17), the relative positional maximum deviation amount ΔYmax between the lens arrays 307 and 309 and the light shielding member 308a is within the range of the relative positional deviation allowable amount ΔQm along the main array direction. I understand.
Therefore, it can be seen that the lens array optical system 302 can prevent a desired image-forming light beam K from being shielded and unnecessary ghost light G from being generated even if such environmental temperature fluctuations occur.

The lens array optical system 302 according to the present embodiment is configured such that the lenses are arranged in two rows in a staggered arrangement in the sub-array direction (Z direction).
Therefore, it is possible to consider relative positional deviation along the sub-array direction of the lens array and the light shielding member.

  When the opening shape of the light shielding members 308a and 308b is not rectangular as in this embodiment, the width Bs of the scattering portion in the sub-array direction is defined as follows. That is, the scattering portion is arranged at a position where the distance between the lens in the A row and the lens in the B row adjacent to the lens is the smallest, and the width Bs in the sub-array direction of the scattering portion is the sub-array cross section of the scattering portion. Defined by the component in the sub-array direction projected onto That is, the width Bs of the scattering portion in the sub-array direction and the width Ts of the light shielding member in the sub-array direction are defined by a cross section perpendicular to the main array direction. That is, it is defined by a section (sub array section) perpendicular to the main array direction including the optical axis of the upper lens array as indicated by a chain line L2 in FIG.

Here, the width Bs of the scattering portion in the sub-array direction is 0.30 mm, and the width Ts of the light shielding member in the sub-array direction is 0.10 mm. That is, Bs and Ts satisfy the relationship represented by the following formula (18).
Bs> Ts (18)

Therefore, similarly to the discussion of Expression (16), if the light shielding member is disposed at the center of the scattering portion, the relative displacement ΔQs along the sub-array direction of the lens array and the light shielding member is expressed by the following expression. It is expressed as (19).
ΔQs = (Bs−Ts) /2=0.10 mm (19)

  It is assumed that a relative displacement ΔZ along the sub-array direction of the lens array and the light shielding member occurs due to an arrangement error or the like during assembly. Even in this case, as long as ΔZ ≦ ΔQs is satisfied, it is possible to obtain an effect of blocking the desired imaging light beam and preventing unnecessary ghost light in the sub-array direction.

  The optical device 300 according to the present embodiment has been in the form of an image reading device, but can of course be applied to an image forming device.

  In the lens array optical system 302 according to the present embodiment, two light shielding members 308 a and 308 b are provided between the first lens array 307 and the original 301 and between the second lens array 309 and the sensor unit 303. Each has a configuration. However, the lens array optical system 302 according to the present embodiment need not be limited to such a configuration. For example, if the lens array optical system 302 satisfies the configuration of the present invention, the lens array optical system 302 has only one light shielding member. However, the effect of the present invention can be obtained.

  In the lens array optical system 302 according to the present embodiment, the configuration of the present invention is discussed for only one of the two columns in the sub-array direction, and the same configuration is assumed for the other column. However, the lens array optical system 302 according to the present embodiment need not be limited to such a configuration, and even if only one column satisfies the configuration of the present invention, the effects of the present invention can be obtained. it can.

  Finally, a monochrome image forming apparatus, a color image forming apparatus and an image reading apparatus provided with the lens array optical system according to the present invention will be described.

  FIG. 12A is a schematic cross-sectional view of a monochrome image forming apparatus 5 including the lens array optical system according to the present invention.

  Code data Dc is input to the image forming apparatus 5 from an external device 15 such as a personal computer. The code data Dc is converted into image data (dot data) Di by the printer controller 10 in the apparatus. The image data Di is input to the exposure unit 1 provided with the lens array optical system according to the present invention. The exposure unit 1 emits exposure light 4 modulated in accordance with the image data Di, and the exposure surface 4 exposes the photosensitive surface of the photosensitive drum 2.

  The photosensitive drum 2 serving as an electrostatic latent image carrier (photoconductor) is rotated clockwise by a motor 13. Above the photosensitive drum 2, a charging roller 3 that uniformly charges the surface of the photosensitive drum 2 is provided so as to contact the surface of the photosensitive drum 2. The exposure unit 4 irradiates the surface of the photosensitive drum 2 charged by the charging roller 3 with exposure light 4.

  As described above, the exposure light 4 is modulated based on the image data Di, and an electrostatic latent image is formed on the photosensitive surface of the photosensitive drum 2 by irradiating the exposure light 4. The formed electrostatic latent image is developed as a toner image by a developing device 6 disposed so as to come into contact with the photosensitive drum 2 further downstream in the rotation direction of the photosensitive drum 2 than the irradiation position of the exposure light 4. The

  The toner image developed by the developing unit 6 is transferred onto a sheet 11 as a transfer material by a transfer roller 7 (transfer unit) disposed below the photosensitive drum 2 so as to face the photosensitive drum 2. The paper 11 is stored in the paper cassette 8 in front of the photosensitive drum 2 (on the right side in FIG. 12A), but can be fed manually. A paper feed roller 9 is disposed at the end of the paper cassette 8, and feeds the paper 11 in the paper cassette 8 into the transport path.

  As described above, the sheet 11 on which the unfixed toner image is transferred is further conveyed to the fixing device 16 behind the photosensitive drum 2 (left side in FIG. 12A). The fixing device 16 includes a fixing roller 12 having a fixing heater (not shown) therein, and a pressure roller 18 disposed so as to be in pressure contact with the fixing roller 12. The unfixed toner image on the sheet 11 is fixed by heating the sheet 11 conveyed from the transfer unit 17 while being pressed by the press contact portion between the fixing roller 12 and the pressure roller 14. Further, a paper discharge roller 14 is disposed behind the fixing device 16, and the fixed paper 11 is discharged out of the image forming apparatus 5.

  The print controller 10 not only converts data but also controls each part in the image forming apparatus 5 including the motor 13.

  By using the lens array optical system according to the present invention, it is possible to make the exposure unit compact, thereby obtaining the effect of making the entire image forming apparatus compact.

  FIG. 12B is a schematic cross-sectional view of a color image forming apparatus 33 provided with a lens array optical system according to the present invention.

  The color image forming apparatus 33 is a tandem type color image forming apparatus in which four optical devices are arranged in parallel and image information is recorded on a photosensitive drum surface as an image carrier. The color image forming apparatus 33 includes optical devices 17, 18, 19, and 20 including the lens array optical system according to the present invention, and photosensitive drums 21, 22, 23, and 24 as image carriers. , Developing devices 25, 26, 27, and 28, and a conveyor belt 34.

  The color image forming apparatus 33 receives R (red), G (green), and B (blue) color signals from an external device 35 such as a personal computer. These color signals are converted into C (cyan), M (magenta), Y (yellow), and K (black) image data (dot data) by a printer controller 36 in the apparatus. These image data are input to the optical devices 17, 18, 19, and 20, respectively. These optical devices emit exposure light 29, 30, 31, 32 modulated according to each image data, and the exposure surfaces of the photosensitive drums 21, 22, 23, 24 are exposed by these exposure light. Is done.

  These exposure lights are modulated based on the image data, and electrostatic latent images are formed on the surfaces of the photosensitive drums 21, 22, 23, 24 charged by a charging device (not shown) by irradiating the exposure light. Let me. The formed electrostatic latent image is further converted into a toner image by developing units 25, 26, 27, and 28 arranged so as to come into contact with the photosensitive drum, further downstream of the exposure light irradiation position in the rotational direction of the photosensitive drum. As developed.

  The toner images developed by the developing device are sequentially transferred onto a sheet 39 as a transfer material. The sheet 39 is stored in the sheet cassette 38 in front of the photosensitive drum (on the right side in FIG. 12B), but can be fed manually.

  As described above, the sheet 39 on which the unfixed toner image is transferred is further conveyed to the fixing unit 37 behind the photosensitive drum 2 (left side in FIG. 12B). The fixing device 37 includes a fixing roller having a fixing heater (not shown) therein, and a pressure roller arranged so as to be in pressure contact with the fixing roller. The sheet 39 that has been conveyed is heated while being pressed by a pressure contact portion between the fixing roller and the pressure roller, thereby fixing the unfixed toner image on the sheet 39. Then, the fixed sheet 39 is discharged out of the image forming apparatus 33.

  As the external device 35, for example, a color image reading apparatus including a CCD sensor may be used. In this case, the color image reading apparatus and the color image forming apparatus 33 constitute a color digital copying machine. The lens array optical system according to the present invention may be used in this color image reading apparatus.

  FIG. 13 is a schematic cross-sectional view of an image reading apparatus 50 including a lens array optical system according to the present invention.

The image reading device 50 includes an image reading unit 41, a frame 42, and a document table 43. The document table 43 is made of a transmissive member and is supported by the frame 42. A document 40 is disposed on the upper surface of the document table 43.
The image reading unit 41 reads the image data of the document 40 by moving in the arrow direction in the figure. The image reading unit 41 includes an illumination unit that illuminates the document 40 through the document table 43, an imaging unit that forms an image of a light beam reflected from the document 40, and a sensor that receives the imaged light beam and uses it as image data. It consists of a unit (light receiving part).

  By using the lens array optical system according to the present invention, the image forming unit can be made compact, thereby obtaining an effect that the entire image reading apparatus can be made compact.

  The lens array optical system according to the present invention has a configuration in which a scattering portion is provided between a lens surface of a lens array and an adjacent lens surface. However, it is not necessary to be limited to the scattering portion, and the effect of the present invention can be obtained even if a light absorption portion is provided instead of the scattering portion.

  The light shielding member in the lens array optical system according to the present invention has a plurality of openings penetrating in the optical axis direction corresponding to the number of lenses constituting the lens array, and the light shielding walls between the adjacent openings are adjacent lenses. It is described as an integrally molded member that is positioned between the two optical axes and arranged to align with the scattering portion. However, the light-shielding member is not necessarily limited to such an integrally molded member. For example, a plurality of plate-like members capable of shielding ghost light are arranged in the main arrangement of the plurality of plate-like members. It is good also as a light shielding member unit obtained when a frame member hold | maintains so that the position in a direction and a subarray direction may be defined.

  The lens array optical system according to the present invention is configured to have an overall length of A4 width (210 mm width). However, it is not necessary to be limited to the A4 width, and it may be configured to have a total length of an arbitrary width.

The lens array optical system according to the present invention has the configuration of the present invention over the entire length of the A4 width. However, it is not necessary to have the configuration of the present invention over the entire length of the lens array optical system, and the effects of the present invention can be obtained even when only a part of the lens array optical system has the configuration of the present invention. Can do.
For example, in the lens array optical system according to the first embodiment, the lens is positioned at the center in the main arrangement direction. Therefore, even if the environmental temperature fluctuates, the relative positional deviation between the lens array and the light shielding member near the center is small. Therefore, the effects of the present invention can be obtained as long as at least lenses near both ends of the lens array optical system have the configuration of the present invention.

  In the lens array optical system according to the present invention, the linear expansion coefficients of the lens array and the light shielding member are different. However, both linear expansion coefficients may be the same. When both linear expansion coefficients are the same, there is no relative displacement between the lens array and the light shielding member when the environmental temperature fluctuates, but there is no relative displacement between the lens array and the light shielding member due to an arrangement error during assembly. Always exists. Therefore, the present invention is effective even when the linear expansion coefficients of the lens array and the light shielding member are the same.

102 Lens array optical system 107 Lens array (first lens array)
108 light shielding member 109 lens array (second lens array)
110 Scattering part

Claims (12)

A first lens array including a plurality of lenses arranged in a first direction and forming an intermediate image of an object in a first cross section parallel to the first direction and the optical axis direction of the plurality of lenses A second lens array that includes a plurality of lenses arranged in the first direction and re-images an intermediate image of the object in the first cross section;
A light shielding member disposed between optical axes of adjacent lenses in the first and second lens arrays;
With
Each of the first and second lens arrays has a scattering part or a light absorbing part between the adjacent lenses,
The lens array optical system according to claim 1, wherein a width of the scattering portion or the light absorption portion in the first direction is larger than a width of the light shielding member in the first direction. In a first cross section including a plurality of lenses arranged in a first direction and a second direction perpendicular to the first direction, and parallel to the first direction and the optical axis direction of the plurality of lenses A first lens array for forming an intermediate image of the object at
A second lens array including a plurality of lenses arranged in the first direction and the second direction, and re-images an intermediate image of the object in the first cross section;
A light shielding member disposed between optical axes of adjacent lenses in the first and second lens arrays;
With
Each of the first and second lens arrays has a scattering part or a light absorbing part between the adjacent lenses,
The lens array optical system according to claim 1, wherein a width of the scattering portion or the light absorbing portion in the second direction is larger than a width of the light shielding member in the second direction. Each of the first and second lens arrays includes a plurality of lenses arranged in the first direction and a second direction perpendicular to the first direction;
2. The lens array optical system according to claim 1, wherein a width of the scattering portion or the light absorption portion in the second direction is larger than a width of the light shielding member in the second direction. ΔL is the distance from the position where the first lens array, the second lens array, and the light shielding member are positioned to the farthest position in the lens array optical system, and ΔT is the first lens. The difference between the temperature when the array, the second lens array and the light shielding member are positioned and the temperature when the lens array optical system is used, ΔX, is the linear expansion of the first lens array. The absolute value of the difference between the coefficient and the linear expansion coefficient of the member defining the position of the light blocking member in the first direction and the second direction, and the linear expansion coefficient of the second lens array and the light blocking member Of the absolute value of the difference from the coefficient of linear expansion of the member defining the position in the first direction and the second direction, ΔW, the scattering along the adjacent lenses Part or suck When parts and width Bm of the difference between the width Tm of the light blocking member along between the adjacent lenses, that,
ΔL × ΔT × ΔX ≦ ΔW / 2
The lens array optical system according to claim 1, wherein: The light shielding member is disposed between the first lens array and the second lens array,
P is the lens arrangement period of the first lens array and the second lens array, Ls is the length of the light shielding member in the optical axis direction, and Lmax is the distance between the first lens array and the second lens array. When the longest distance in the optical axis direction between the opposing faces,
Bm + Tm ≧ P × (1− (Ls / Lmax))
The lens array optical system according to claim 4, wherein:   The length of the light shielding member in the optical axis direction is smaller than the shortest distance in the optical axis direction between the opposing surfaces of the first lens array and the second lens array. 5. The lens array optical system according to 5.   5. The light shielding member according to claim 1, wherein the light shielding member is disposed on at least one of an object side with respect to the first lens array and an image side with respect to the second lens array. The lens array optical system according to 1.   The lens array optical system according to claim 1, wherein the scattering unit includes a plurality of prisms. When Be is the distance between the ridgelines of the first prism from both ends of the scattering part,
Tm ≧ Be
The lens array optical system according to claim 8, wherein: ΔL = 105mm, ΔT = 30 ° C. ΔL × ΔT × ΔX ≦ ΔW / 2
The lens array optical system according to claim 4, wherein:   A lens array optical system according to any one of claims 1 to 10, a light source having a plurality of light emitting points, and a photoreceptor in which the lens array optical system is arranged on an image plane by a light beam emitted from the light source. A developing device that develops the electrostatic latent image formed on the photosensitive surface as a toner image, a transfer device that transfers the developed toner image to a transfer material, and the transferred toner image on the transfer material An image forming apparatus comprising: a fixing device for fixing.   11. The lens array optical system according to claim 1, an illumination unit that irradiates a document, and a plurality of light receiving units that receive light beams from the document collected by the lens array optical system; An image reading apparatus comprising:

Images