JPH10322521A - Linear light generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To emit linear light from a spot light source unit while efficiently uniforming its illuminance distribution at a short distance. SOLUTION: A spot light source unit 20 for emitting linear light is formed by sequentially installing plural light emitting diodes 22 of spot light sources. Then, an illuminance uniforming means 30A is provided for reducing the illuminance distribution of line light in the linear direction at least. In that case, a refraction gracting 35A is formed on the relevant illuminance uniforming means 30A so as to refract incident line light in the linear direction. Thus, the linear light is refracted in the linear direction and the illuminance distribution is uniformed in the relevant line direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a line light generator capable of emitting uniform light in a line direction in a line light from a point light source unit.

[0002]

2. Description of the Related Art Conventionally, in an image reading apparatus or the like, line light from a line light generator is applied to a document, and information recorded on the document is read from the reflected light.

In such a line light generating device, a point light source unit in which light emitting elements such as light emitting diodes (LEDs), which are point light sources, are arranged in rows is used.

However, in a point light source unit in which point light sources are simply arranged, uneven illuminance distribution occurs in the line direction, and the reflected light from the original or the like includes the influence of the uneven illuminance distribution. There is a problem that it is difficult to accurately read the stored information.

Therefore, in order to cope with such a problem, the distance between the point light source unit and the irradiation position (position on a document or the like) is made sufficiently long so that light is sufficiently diverged to thereby make the illuminance distribution uniform. ing.

However, when the distance between the point light source unit and the illuminating position is increased, the line light generator becomes larger, and the space for installing the line light generator becomes more difficult. Occur.

Further, since the light emitting element is a point light source, the emitted light becomes divergent light. Therefore, as the distance between the point light source unit and the illumination position increases, the amount of light diverging in the direction perpendicular to the line direction also increases, and the efficiency of using the light decreases.

In order to solve the above-mentioned problems, it is necessary to increase the number of light emitting elements to generate line light with a small unevenness in the illuminance distribution. In this case, however, the cost of the line light generator is increased. I will invite you.

Therefore, in Japanese Patent Application Laid-Open No. Hei 7-162586, a light guide plate made of a plurality of transparent members having different refractive indexes is provided between a point light source unit and an illumination position, and light is transmitted from the point light source unit to the illumination position. In addition, the degree of divergence of light in the line direction is increased to achieve uniform illuminance distribution.

That is, in the above publication, as shown in FIG. 17, a transparent member 104 formed by laminating a member 102 having a large refractive index and a member 103 having a small refractive index in order in the emission direction of the light emitting element 101. Is provided.

Then, each member 102, 1 having a different refractive index.
By utilizing the fact that the divergence angle increases from φ1 to φ2 due to refraction when passing through the bonding surface of No. 03, the illuminance distribution in the line direction at the irradiation position is reduced and the light emitting element 101
The distance P1 between the lighting position and the lighting position is reduced.

As a method of increasing the divergence of light, there is a method using a lens array as shown in FIG. FIG. 20A is a side view, and FIG.
Is a perspective view thereof.

[0013]

However, in the configuration according to the above publication, as shown in FIG. 18, there is an advantage when the entire transparent member 105 is formed of the same material as the member 102 having a large refractive index. However, FIG.
As shown in the figure, the transparent member 106 is a member 1 having a small refractive index.
There is no merit when formed of the same material as 03.

That is, when the transparent member 106 is formed of the same material as the member 103 having a small refractive index, the transparent member 10
Since the divergence angle becomes φ2 when the light passes through the incident surface of No. 6, the same divergence effect can be obtained at a shorter distance P1 than the configuration shown in FIG. 17 by combining members having different refractive indexes. Therefore, it is not possible to achieve more uniformity than the uniformity of the illuminance distribution achieved in the case of FIG.

In the method using a lens array as shown in FIG. 20, the arrangement pitch of the lenses 111 and the arrangement pitch of the light emitting elements 110 are matched, and the optical axis of the corresponding lens and the optical axis of the light emitting element are matched. Therefore, there is a problem that high accuracy is required for component accuracy, assembly accuracy, and the like, which causes an increase in cost.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a line light generating device that efficiently and uniformly emits the illuminance distribution of line light from a point light source unit over a short distance.

[0017]

According to a first aspect of the present invention, there is provided a point light source unit in which a plurality of light emitting elements are arranged in a row and emits linear light, and a diffraction grating for diffracting linear light. Illuminance uniforming means for uniformizing the illuminance distribution at least in the line direction.

That is, a plurality of light-emitting elements as point light sources are arranged in line to form a point light source unit that emits linear light. In addition, an illuminance uniforming means provided with a diffraction grating for diffracting incident light in the line direction is provided. Then, the line light from the point light source unit enters the illuminance uniforming means and is diffracted in the line direction, whereby the illuminance distribution in the line direction is made uniform and emitted.

According to a second aspect of the present invention, the illuminance uniforming means is formed of a substantially plate-shaped transparent member, and the plate surface is disposed along the point light source unit. Then, a diffraction grating is formed on at least one of the entrance surface and the exit surface when the linear light passes through the transparent member, and the incident linear light is diffracted in the line direction and emitted to emit illuminance. It is characterized by having a uniform distribution.

According to a third aspect of the present invention, the illuminance uniforming means is formed by laminating a plurality of substantially plate-shaped transparent members, and the plate surface is arranged along the point light source unit. Then, a diffraction grating is formed on at least one of the incident surface, the outgoing surface, and the laminated surface when the linear light from the point light source unit passes through the transparent member, and the incident linear light is transmitted in the line direction. It is characterized in that the illuminance distribution is efficiently made uniform by diffracting and emitting.

According to a fourth aspect of the present invention, the illuminance uniforming means is formed of a substantially plate-shaped transparent member, and is disposed such that its plate thickness surface is along the point light source unit. Then, a diffraction grating is formed on at least one of the incident surface and the outgoing surface when the linear light passes through the transparent member, and the incident linear light is diffracted in the line direction. In addition to making the illuminance distribution uniform, the plate surface of the transparent member is formed as a reflective surface, so that light is reflected alternately on the opposing plate surfaces, and the incident light diverges in a direction orthogonal to the line direction. It is characterized by preventing.

According to a fifth aspect of the present invention, the transparent member has a trapezoidal cross section in which the plate thickness decreases toward the light exit surface. While preventing the light from diverging in a direction orthogonal to the line direction while alternately reflecting the incident light on the opposing plate surfaces, the diffraction grating on the incident surface or the output surface prevents the light from diffusing in the line direction. The illuminance distribution is made uniform.

According to a sixth aspect of the present invention, there are provided two side surfaces substantially perpendicular to the entrance surface and the exit surface in the illuminance uniforming means, which are formed in the line direction and substantially perpendicular to the entrance surface and the exit surface. At least one pair of two opposing end surfaces that are orthogonal to the line direction is a reflection surface. Further, a diffraction grating is formed on the reflection surface. And, it is characterized in that incident linear light is diffracted in the line direction.

According to a seventh aspect of the present invention, at least one of the incident surface and the outgoing surface is formed as a convex curved surface that converges divergent light so as to be substantially parallel light, and makes effective use of incident light. It is characterized in that the illuminance distribution is made uniform while aiming.

In the invention according to claim 8, the illuminance uniforming means has a reflecting surface arranged in parallel with the point light source unit, and the diffraction grating is formed on the reflecting surface. At the same time, the incident linear light is reflected, and at the same time, the linear light is diffracted in the line direction, so that the illuminance distribution is made uniform and the degree of freedom in layout is increased.

According to a ninth aspect of the present invention, the reflection surface is formed as a concave curved surface, and the reflected light is formed so as to be substantially parallel light, thereby making the illuminance distribution uniform while effectively utilizing the incident light. It is characterized by doing so.

According to a tenth aspect of the present invention, the illuminance uniforming means is formed of a substantially triangular prism-shaped transparent member juxtaposed with the point light source unit, wherein one side of the member forms a reflecting surface and the other two sides form a reflecting surface. Make an entrance surface and an exit surface. And at least one of the reflecting surface, the incident surface, and the outgoing surface.
A diffraction grating for diffracting light incident on one side surface in the line direction is formed to make the illuminance distribution uniform and increase the degree of freedom in layout.

According to an eleventh aspect of the present invention, at least one of the incident surface, the outgoing surface and the reflecting surface is formed as a convex or concave curved surface so that the light emitted from the outgoing surface becomes substantially parallel light. The present invention is characterized in that the illuminance distribution is made uniform while the incident light is effectively used, and the degree of freedom in layout is increased.

According to a twelfth aspect of the present invention, the illuminance uniforming means is formed of two reflecting members facing each other, and these are arranged along the point light source unit. Then, the opposing surface is made a reflection surface, and the linear light incident on the reflection surface is reflected while diffracting in the line direction so as to make the illuminance distribution uniform.

According to a thirteenth aspect of the present invention, there is provided a document plate on which a document is placed, and a point light source unit in which a plurality of light emitting elements disposed below the document plate are arranged in a row to emit linear light. In a line light generating device used in an image reading apparatus having a light receiving element for receiving light reflected by a document and performing photoelectric conversion on the document, a linear light applied to the document is transmitted through a document plate. A diffraction grating for diffracting the light in the line direction is formed on the surface, and the diffraction grating is formed so as not to diffract light reflected from a document incident on the light receiving element.

That is, the line light generator is constituted by a point light source unit and a document plate, and the light from the point light source unit incident on the document plate is diffracted in the line direction, and
It is characterized in that a diffraction grating is formed on the original plate so as to make the illuminance distribution uniform so that the reflected light from the original is not diffracted.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of a line light generating device 1 according to the present embodiment, and FIG. 2 is a side view as viewed from the direction of arrow A in FIG.

The line light generator 10A comprises a point light source unit 20 and illuminance uniforming means 30A.

The point light source unit 20 includes a substrate 21, and light emitting diodes 22 of point light sources arranged at predetermined intervals in the longitudinal direction of the substrate 21, and the longitudinal direction of the substrate 21 (the direction is defined as a line direction). (Indicated as "line light").

In this specification, the term “side view” means a side view as viewed in the line direction.

The illuminance uniforming means 30A includes a transparent member 31A made of a transparent resin, glass, or the like, and a diffraction grating 35A formed by engraving a grating on the incident surface 33A of the transparent member 31A in the direction of arrow A shown in FIG. Is shaped.

With such a configuration, the point light source unit 2
The line light from 0 is incident on the incident surface 33 of the illuminance uniforming means 30A.
A and the diffraction grating 3 formed on the incident surface 33A.
The light is diffracted at 5A and exits from the exit surface 34A.

Generally, a diffraction grating is formed by arranging a large number of linear gratings. When light is incident on the grating, the light is diffracted in a direction perpendicular to the direction of the grating (the direction in which the gratings are arranged). The resulting light has a characteristic of being emitted as diffracted light of ± n order light (n is an integer).

The 0th-order diffracted light travels straight without changing the optical path at a diffraction angle of zero, and the + order diffracted light and-
The diffracted light of the order is diffracted at a diffraction angle corresponding to the order. +
The diffraction directions of the diffracted light of the order and the diffracted light of the -order are on the same plane with respect to the diffracted light of the zero-order light and are opposite to each other.

The intensity distribution of each order shows a Gaussian distribution, and the peak intensity decreases as the order increases.

The light emitted from the light emitting diode 22 is a divergent light. In the following description, the light on the optical axis of the light emitting diode 22 is focused, and the diffracted light is reduced to 0,
The following description focuses on ± first order light. For example, in FIG. 2, light on the optical axis of the light emitting diode 22 is described as L, 0th-order light as La, + 1st-order light as Lb, and -1st-order light as Lc.

In the present invention, the diffraction grating 35A is provided as described above in order to increase the divergence of the line light in the line direction and suppress the illuminance distribution in the line direction by utilizing the characteristics of the diffraction grating.

The zero-order light travels straight on the optical axis of each light-emitting diode 22, and the ± first-order lights are diffracted in the line direction to reach the respective illumination positions, as shown in the illuminance distribution shown in FIG. become. The dashed lines in FIGS. 2 and 3 show the illuminance distribution at the irradiation position.

FIG. 3 is a diagram showing an illuminance distribution when the illuminance uniforming means 30A having the above configuration is not used. The illuminance on the optical axis of the light emitting diode 22 is extremely high, and
Is a distribution that directly reflects the illuminance distribution of the line light emitted from.

As can be easily understood from the comparison between FIG. 3 and FIG. 2, the provision of the illuminance uniforming means 30A according to the present invention makes it possible to reduce the illuminance distribution at the illuminating position. It is possible to obtain an illuminance distribution as when increasing the number of.

Next, a second embodiment of the present invention will be described with reference to the drawings. Note that the same components as those of the first embodiment are denoted by the same reference numerals and description thereof will be omitted as appropriate.

In the first embodiment, the incident surface 33
Although the diffraction grating 35A is formed only on the light incident surface A, the present invention is not limited to this, and as shown in FIG.
The illuminance uniforming means 30B may be provided with a diffraction grating 37B not only on 3A but also on the exit surface 34A.

In this case, the light from the point light source unit 20 is diffracted into ± n order light by the diffraction grating 35A provided on the incident surface 33A, and the light of each order is further ±± diffused by the diffraction grating 37B provided on the emission surface 34A. Diffracted into n-order light. Therefore, it is possible to further uniform the illuminance distribution at the irradiation position.

Next, a third embodiment of the present invention will be described with reference to the drawings. It is to be noted that the same components as those in the above embodiments are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

Although the illuminance uniforming means described so far is formed by one transparent member, the present invention is not limited to this. The transparent member may be formed by laminating a plurality of transparent members.

FIG. 5 shows a line light generator 10C using the illuminance uniforming means 30C formed of two transparent members from such a viewpoint.

Diffraction gratings 35C, 37C and 36 are provided on the entrance surface 33C, the exit surface 34C and the lamination surface of the illuminance uniforming means 30C.
C is formed, and the incident light is diffracted into ± n-order light and emitted.

Therefore, the line light is diffracted into ± n order light by the diffraction grating 35C formed on the incident surface 33C, and the ± n order light is converted into ± n order light by the diffraction grating 36C formed on the laminated surface. Diffracted. Further, the diffraction grating 3
The diffracted light from 6C is diffracted into ± n-order light by the diffraction grating 37C formed on the emission surface 34C, and is emitted.

As described above, it is possible to increase the uniformity of the illuminance distribution in the line direction by performing the diffraction many times.

It should be noted that the number of the transparent members to be regularly used is not limited to two, but can be set as appropriate.

Next, a fourth embodiment of the present invention will be described with reference to the drawings. It is to be noted that the same components as those in the above embodiments are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

The incident surface, the outgoing surface and the like in the illuminance uniforming means described above are all flat. However, the present invention is not limited to this, and may have a configuration as shown in FIG.

FIG. 6 is a side view of the line light generating device 10D.
A 1D entrance surface 33D is formed in a plane, and its exit surface 34
D is formed on a convex curved surface.

Thus, the illuminance uniforming means 30D acts as a cylindrical lens, and the light emitted from the emission surface 34D becomes substantially parallel light.

A diffraction grating (not shown) is provided on one of the incident surface 33D and the outgoing surface 34D, or on both surfaces.

As a result, while making the illuminance distribution in the line direction uniform, all the incident line light can be irradiated to the irradiation position, and the light can be used effectively.

It is needless to say that the incident surface 33D may be a convex curved surface and the exit surface 34D may be a flat surface.

Next, a fifth embodiment of the present invention will be described with reference to the drawings. It is to be noted that the same components as those in the above embodiments are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

FIG. 7 is a side sectional view of the line light generating apparatus according to the present embodiment. In the transparent member 31E of the illuminance uniforming means 30E in the line light generating device 10E shown in the figure, the entrance surface 33E and the exit surface 34E are each formed into a convex curved surface, and the entrance surface 33E or the exit surface 34E is formed.
A diffraction grating (not shown) is provided on at least one of them.

By adopting such a configuration, it is possible to effectively use light while making the illuminance distribution in the line direction uniform.

Next, a sixth embodiment of the present invention will be described with reference to the drawings. It is to be noted that the same components as those in the above embodiments are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

FIG. 8 is a perspective view of the line light generator 10F according to the present embodiment, and shows the illuminance uniforming means 3.
0F has a substantially triangular prism-shaped reflecting member 31F, and the light from the point light source unit 20 is reflected by the reflecting surface 32 of the reflecting member 31F.
The light is reflected by F and reaches the irradiation position.

A diffraction grating 33F is formed on the reflection surface 32F so as to reflect the incident line light and diffract it in the line direction.

Therefore, the illuminance distribution at the illuminating position can be reduced, and the illuminance distribution can be made as if the number of light emitting diodes 22 were increased.

Further, since the optical path can be deflected, the restrictions on the layout of the illuminance uniforming means 30F and the point light source unit 20 are relaxed, and the apparatus can be more compactly incorporated into the applicable device.

Next, a seventh embodiment of the present invention will be described with reference to the drawings. It is to be noted that the same components as those in the above embodiments are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

The line light generator 1 according to the present embodiment
The 0G illuminance uniforming means 30G has substantially the same shape as the illuminance uniforming means 30F according to the sixth embodiment, but is characterized in the arrangement direction and the like.

FIG. 9A is a perspective view of a line light generator 10G according to the present embodiment, and FIG. 9B is a sectional view thereof.

The reflecting member 31G of the illuminance uniforming means 30G in the line light generating device 10G shown in the figure is made of a transparent member, one short side surface being the entrance surface 32G, the other short side surface being the exit surface 33G, and the slope being the inclined surface. It forms a reflecting surface 34G.

Then, the line light incident from the incident surface 32G is reflected by the reflection surface 34G and deflected in the optical path, and then exits from the exit surface 33G. At this time, a diffraction grating (not shown) is formed on the entrance surface 32G, the exit surface 33G, and the reflection surface 34G so as to make the illuminance distribution of the line light uniform.

Needless to say, the diffraction grating has an entrance surface 32G and an exit surface 3G.
It is not necessary to provide it on all of the 3G and the reflecting surface 34G, and it is possible to arrange them arbitrarily according to the situation.

Next, an eighth embodiment of the present invention will be described with reference to the drawings. It is to be noted that the same components as those in the above embodiments are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

Since the diverging light is emitted from the light emitting diodes 22 and the like, when the line light is reflected by the reflecting surface in the seventh embodiment, the divergence angle becomes further larger, and the diverging angle in the direction perpendicular to the line direction is increased. In some cases, the illuminance is reduced, and the light use efficiency is reduced.

In such a case, as shown in FIG.
At least one of the incident surface, the reflecting surface, and the reflecting surface may have a convex or concave curved surface to converge the incident line light so as to enhance the light use efficiency.

The line light generator 10 shown in FIG.
The H illuminance uniforming means 30H has substantially the same configuration as that of FIG. 8 except that the reflection surface 31H is formed as a concave curved surface.
H shows a case where a diffraction grating (not shown) is formed.

The incident line light is reflected by the reflection surface 3
The light is reflected at 1H and converged to become substantially parallel light, which reaches the irradiation position. As a result, effective use of the incident light is achieved.

The illuminance uniforming means 30I of the line light generating apparatus 10I shown in FIG. 10B has substantially the same configuration as that of FIG. 9 except that the reflecting surface 32I is formed in a convex curved surface and the incident surface 31 is formed.
A diffraction grating (not shown) is formed on at least one of I, the reflection surface 32I, and the emission surface 33I.

Also in this case, similarly to the above, the incident line light is reflected by the reflection surface 32I and is converged into substantially parallel light, thereby effectively utilizing the incident light.

Further, the illuminance uniforming means 30J of the line light generating device 10J shown in FIG. 10C has substantially the same configuration as that of FIG. 9 except that the entrance surface 31J and the exit surface 33J are formed as convex curved surfaces. 31J, reflection surface 32J or emission surface 33J
A diffraction grating (not shown) is formed on at least one surface.

Then, the incident line light is transmitted to the incident surface 31J.
For effective use of the incident light and the reflection surface 3
The light reflected by the 2J is further converged on the exit surface 33J to be converted into substantially parallel light and emitted, thereby achieving effective use of the light.

In FIGS. 10A to 10C, since the diffraction grating (not shown) is provided as described above, the illuminance distribution in the line direction can be made uniform, and the illuminance distribution at the illumination position can be achieved. Can be reduced.

Next, a ninth embodiment of the present invention will be described with reference to the drawings. It is to be noted that the same components as those in the above embodiments are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

FIG. 11A is a perspective view of a line light generator 10K according to the present embodiment, and FIG. 11B is a sectional view of the same.

The illuminance uniforming means 30K is formed of a substantially plate-shaped transparent member 31K, and one of the plate thickness surfaces is the incident surface 32K,
The other plate surface is the emission surface 33K, and the opposite plate surface is the reflection surface 3.
4K.

The light incident on the illuminance uniforming means 33K from the incident surface 32K is alternately reflected on the opposing reflecting surfaces 34K and is emitted from the emitting surface 33K.

Therefore, the illuminance distribution in the direction orthogonal to the line direction (the thickness direction of the transparent member 31K) can be made uniform, and substantially all of the light incident on the incident surface 32K is applied to the irradiation position. And the light use efficiency can be improved.

Of course, also in this case, the entrance surface 32K and the exit surface 3
By providing a diffraction grating (not shown) on at least one of the 3K and the reflection surface 34K, it is possible to make the illuminance distribution in the line direction uniform.

Further, as shown in FIG. 12, if end faces 35K on both sides of a transparent member 31K formed in a plate shape are formed on a reflection surface, and a diffraction grating is provided on the side face 35K, the end face 35K is formed on the end face 35K. Effective use of incident light is achieved,
In addition, it is possible to make the illuminance distribution in the line direction uniform.

Next, a tenth embodiment of the present invention will be described with reference to the drawings. It is to be noted that the same components as those in the above embodiments are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

FIG. 13 is a side view of the line light generator 10L according to the present embodiment, and
0L is formed by a substantially plate-shaped transparent member 31L, one of the plate thickness surfaces is formed into a convex curved surface to form an entrance surface 32L, the other plate thickness surface is an emission surface 33L, and the opposite plate surface is a reflection surface. 34L.

The light incident on the illuminance uniforming means 33L from the incident surface 32L is converged and reflected by the opposing reflecting surface 3L.
The light is emitted from the emission surface 33L while being alternately reflected by 4L.

With this configuration, the degree of divergence of the light emitted from the emission surface 33L can be reduced, and the illumination position changes in the plate surface direction (the direction of arrow A in FIG. 13). This also makes it possible to suppress a change in illuminance at the illumination position.

Of course, also in this case, the entrance surface 32L and the exit surface 3
By providing a diffraction grating (not shown) on at least one surface of the 3L or the reflecting surface 34L, the illuminance distribution in the line direction can be made uniform, and the plate-shaped transparent member 31 can be provided.
If the end faces on both sides of L are formed as reflection surfaces and a diffraction grating is provided on the end face, the light incident on the end face can be effectively used and the illuminance distribution in the line direction can be made uniform. Becomes possible.

Next, an eleventh embodiment of the present invention will be described with reference to the drawings. It is to be noted that the same components as those in the above embodiments are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

FIG. 14 is a side view of a line light generating apparatus 10M according to the present embodiment, in which
0M is formed by a substantially plate-shaped transparent member 31M, one of the plate-thick surfaces is the entrance surface 32M, and the other plate-thick surface is the exit surface 33M.
M, the opposing plate surface forms a reflection surface 34M.

The light incident on the illuminance uniforming means 33M from the incident surface 32M is converged and reflected by the opposing reflecting surface 3M.
The light is emitted from the emission surface 33M while being alternately reflected at 4M.

With such a configuration, the emitted light can be focused and irradiated in a narrower range, and the illuminance at the irradiation position can be increased.

Of course, also in this case, the entrance surface 32M and the exit surface 3
By providing a diffraction grating (not shown) on at least one of the 3M and the reflection surface 34M, it is possible to make the illuminance distribution uniform in the line direction, and the plate-shaped transparent member 31 is provided.
If the end surfaces on both sides of M are formed as reflection surfaces and a diffraction grating is provided on the end surface, the light incident on the end surface can be effectively used and the illuminance distribution in the line direction can be made uniform. Becomes possible.

Next, a twelfth embodiment of the present invention will be described with reference to the drawings. It is to be noted that the same components as those in the above embodiments are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

FIG. 15 is a side view of the line light generating apparatus 10N according to the present embodiment, and
In 0N, two reflection plates 31N and 32N are disposed so as to face each other, a facing surface is formed on a reflection surface, and a diffraction grating (not shown) is formed.

The incident light is alternately reflected by the opposing reflecting surfaces and diffracted, so that substantially all of the incident light can be irradiated to the irradiation position, and the light can be irradiated in the line direction and the direction perpendicular to the line direction. It is possible to make the illuminance distribution uniform.

Next, a thirteenth embodiment of the present invention will be described with reference to the drawings. It is to be noted that the same components as those in the above embodiments are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

FIG. 16 is a schematic cross-sectional view of the image reading device 50. In the figure, a point light source unit 2
Reference numeral 0 denotes a rod lens array 5 which is disposed below the original plate 51 made of a transparent member and is adjacent to the point light source unit 20.
2 are provided. A sensor substrate 54 on which a sensor 53 is mounted is provided below the rod array lens 52. These are stored in the frame 55.

The point light source unit 20 is arranged so that the optical axis of the line light is at a predetermined angle with respect to the document surface 56, and the light emitted from the point light source unit 20 enters the document plate 51. , Are reflected by an original (not shown). After that, the reflected light passes through the rod lens array 52 and passes through the sensor 5.
3 is received.

A diffraction grating 58 is formed on the surface 57 of the original plate 51 on the point light source unit 20 side.
Is the horizontal direction in FIG. 16 and is a direction orthogonal to the line direction.

The area where the diffraction grating 58 is formed corresponds to the rod lens array 5 out of the reflected light from the original.
In order to prevent the diffraction grating 58 from performing a diffractive action on the reflected light incident on the light source 2, the diffraction grating 58 is formed so as to avoid a region where the reflected light passes.

Therefore, the line light from the point light source unit 20 is diffracted in the line direction by the diffraction grating 58,
Since the illuminance distribution in the line direction is made uniform to irradiate the original, the illuminance distribution on the original surface can be made uniform.

Also, since the reflected light from the original is not diffracted by the diffraction grating 58, it is possible to perform a good two-line reading.

The diffraction grating used in each of the embodiments described above eliminates the need for alignment between the light source 110 and the lens 111, which is required when using a lens array as shown in FIG. There is an advantage that high accuracy is not required for assembly accuracy.

[0115]

According to the first aspect of the present invention, since the linear light from the point light source unit is diffracted in the line direction by the diffraction grating by the illuminance uniforming means, the illuminance distribution in the line direction can be shortened. The distance can be made uniform.

According to the second aspect of the present invention, since the diffraction grating is formed on at least one of the entrance surface and the exit surface of the illuminance uniforming means, the linear light can be diffracted in the line direction and emitted. As a result, the illuminance distribution in the line direction can be made uniform.

According to the third aspect of the present invention, a plurality of transparent members are laminated to form an illuminance uniforming means, and the incident surface,
Since the diffraction grating is formed on at least one of the emission surface and the lamination surface, the illuminance distribution in the line direction can be efficiently made uniform.

According to the fourth aspect of the present invention, the plate-like transparent member is disposed along the point light source unit, and the diffraction grating is formed on at least one of the entrance surface and the exit surface. As a result, the incident line-shaped light is diffracted in the line direction, making it possible to make the illuminance distribution in that direction uniform, and alternately reflected by the opposing plate surfaces to be emitted. Thus, it is possible to prevent the incident linear light from diverging in the direction orthogonal to the line direction.

According to the fifth aspect of the invention, light incident on the transparent member having a trapezoidal cross section is alternately reflected on the plate surface and emitted, so that divergence in a direction orthogonal to the line direction is prevented. At the same time, the illuminance distribution in the line direction can be made uniform by the diffraction grating on the entrance surface or the exit surface.

According to the invention of claim 6, at least one of the two opposing plate surfaces and the two opposing end surfaces is formed as a reflection surface and a diffraction grating is formed. It is possible to make the illuminance distribution in the line direction uniform while effectively utilizing the line-shaped light.

According to the seventh aspect of the present invention, at least one of the incident surface and the outgoing surface is formed as a convex curved surface, so that the linear light that is the incident divergent light is converged into a substantially parallel light, and Can be effectively used.

According to the eighth aspect of the present invention, since the diffraction grating is formed on the reflecting surface arranged in parallel with the point light source unit,
At the same time as reflecting the incident linear light, the linear light is diffracted in the line direction, so that the illuminance distribution can be made uniform and the degree of freedom in layout can be increased.

According to the ninth aspect of the present invention, since the reflecting surface is formed as a concave curved surface, the reflected light can be made substantially parallel light and emitted, and the illuminance distribution can be made uniform while effectively utilizing the incident light. Will be possible.

According to the tenth aspect of the present invention, one side surface of the transparent member is used as a reflection surface, and the other two side surfaces are used as an entrance surface and an exit surface. By forming a diffraction grating for diffracting light incident on one side surface in the line direction, it is possible to make the illuminance distribution uniform and increase the degree of freedom in layout.

According to the eleventh aspect, at least one of the incident surface, the outgoing surface and the reflecting surface is formed as a convex or concave curved surface, so that the light emitted from the outgoing surface becomes substantially parallel light. Thus, it is possible to make the illuminance distribution uniform while effectively utilizing the incident light, and to increase the degree of freedom in layout.

According to the twelfth aspect of the present invention, since the two reflecting members whose opposing surfaces form a reflecting surface on which a diffraction grating is formed are arranged along the point light source unit, a line incident on the reflecting surface is provided. Light can be reflected while diffracting in the line direction, and the illuminance distribution can be made uniform while effectively utilizing the incident light.

According to the thirteenth aspect, the diffraction grating is formed on the original plate so that the light from the point light source unit incident on the original plate is diffracted in the line direction and the reflected light from the original is not diffracted. Therefore, it is possible to make the illuminance distribution uniform and to receive reflected light that is not affected by the diffraction grating.

[Brief description of the drawings]

FIG. 1 is a perspective view of a line light generation device applied to the description of a first embodiment of the present invention.

FIG. 2 is a side view as viewed from a line direction in FIG. 1;

FIG. 3 is a configuration diagram of a line light generating apparatus in a case where an illuminance uniforming unit is omitted in FIG.

FIG. 4 is a side view in a line direction of a line light generation device applied to the description of a second embodiment of the present invention.

FIG. 5 is a side view in a line direction of a line light generation device applied to the description of a third embodiment of the present invention.

FIG. 6 is a side view in a line direction of a line light generation device applied to the description of a fourth embodiment of the present invention.

FIG. 7 is a side view in a line direction of a line light generation device applied to the description of a fifth embodiment of the present invention.

FIG. 8 is a perspective view of a line light generating device applied to the description of a sixth embodiment of the present invention.

FIG. 9 is a configuration diagram of a line light generation device applied to the description of a seventh embodiment of the present invention.

FIG. 10 is a side view in the line direction of a line light generation device applied to the description of an eighth embodiment of the present invention.

FIG. 11 is a perspective view of a line light generator applied to the description of a ninth embodiment of the present invention.

FIG. 12 is a side view in the line direction of a line light generation device applied to the description of a ninth embodiment of the present invention.

FIG. 13 is a side view in the line direction of a line light generation device applied to the description of a tenth embodiment of the present invention.

FIG. 14 is a side view in the line direction of a line light generation device applied to the description of an eleventh embodiment of the present invention.

FIG. 15 is a perspective view of a line light generation device applied to the description of a twelfth embodiment of the present invention.

FIG. 16 is a side view of the image reading apparatus applied to the description of the thirteenth embodiment of the present invention.

FIG. 17 is a configuration diagram of a line light generation device applied to the description of a conventional technique.

FIG. 18 is a configuration diagram of a line light generation device applied to the description of a conventional technique.

FIG. 19 is a configuration diagram of a line light generation device applied to the description of a conventional technique.

FIG. 20 is a configuration diagram of a line light generation device applied to the description of a conventional technique.

[Explanation of symbols]

 10A to 10N Line light generator 20 Point light source unit 21 Substrate 22 Light emitting diode 30A to 30N Illumination uniformity means 33A, 37B, 36C Diffraction grating

Claims (13)

[Claims] 1. A point light source unit in which a plurality of light-emitting elements are arranged in a line to emit linear light, and a diffraction device for diffracting at least the linear light in a line direction to uniform an illuminance distribution in the line direction. A line light generator comprising: an illuminance uniforming means provided with a grating. 2. The illuminance uniforming means comprises a substantially plate-shaped transparent member having a plate surface disposed along the point light source unit, and an incident surface when the linear light is transmitted through the transparent member. 2. The line light generator according to claim 1, wherein the diffraction grating is formed on at least one of the emission surfaces. 3. The illuminance uniforming means is formed by laminating a plurality of substantially plate-shaped transparent members having a plate surface arranged along the point light source unit, and the transparent member is formed by the linear light source. 2. The line light generating device according to claim 1, wherein the diffraction grating is formed on at least one of an incident surface, an outgoing surface, and a laminated surface when the light is transmitted. 4. The illuminance uniforming means is formed of a substantially plate-shaped transparent member, and the plate-like surface of the transparent member is disposed along the point light source unit, and the linear light is transmitted by the transparent member. The diffraction grating is formed on at least one of the incident surface and the outgoing surface when transmitting the light, and the linear light that is incident is diffracted in the line direction to uniform the illuminance distribution in the line direction. The plate surface of the transparent member is formed on the reflection surface, and the linear light incident thereon is alternately reflected by the opposing plate surfaces to prevent divergence in a direction perpendicular to the line direction, thereby improving light use efficiency. The line light generating device according to claim 1, wherein: 5. The transparent member is formed to have a trapezoidal cross section in which the thickness of the transparent member decreases toward an emission surface, and the illuminance is increased while alternately reflecting incident light on opposite plate surfaces.
5. The line light generator according to claim 4, wherein the illuminance distribution of the light in the line direction is made uniform. 6. A side surface substantially orthogonal to the entrance surface and the exit surface in the illuminance uniforming means, and two opposite plate surfaces formed in the line direction and a side surface approximately orthogonal to the entrance surface and the exit surface. Wherein at least one pair of two opposing end surfaces orthogonal to the line direction is formed on a reflection surface, and the diffraction grating is formed on the reflection surface, so that incident linear light can be transmitted to a line. The line light generating device according to claim 4, wherein the light is diffracted in a direction. 7. The device according to claim 2, wherein at least one of the incident surface and the outgoing surface is formed as a convex curved surface that converges divergent light into substantially parallel light.
Item 7. A line light generating device according to item 1. 8. The illuminance uniforming means has a reflection surface arranged in parallel with the point light source unit, and the diffraction grating is formed on the reflection surface to reflect incident line light and to form the line-shaped light. 2. The line light generator according to claim 1, wherein the light is diffracted in a line direction. 9. The line light generating device according to claim 8, wherein the reflection surface is formed as a concave curved surface, and the reflected light is set to be substantially parallel light. 10. The illuminance uniforming means comprises a substantially triangular prism-shaped transparent member juxtaposed with the point light source unit.
One side surface of the transparent member forms a reflection surface, and the other two surfaces form an entrance surface and an exit surface, and light incident on at least one of the reflection surface, the entrance surface, and the exit surface is directed in a line direction. 2. The line light generating device according to claim 1, wherein a diffraction grating for diffracting the light is formed. 11. At least one of the incident surface, the outgoing surface, and the reflecting surface is formed as a convex or concave curved surface so that light emitted from the outgoing surface becomes substantially parallel light. The line light generator according to claim 10, wherein: 12. The illuminance uniforming means comprises two reflecting members arranged along the point light source unit such that reflecting surfaces face each other, and the diffraction grating is formed on the reflecting surface. 2. The line light generating apparatus according to claim 1, wherein the line light is reflected while diffracting the incident linear light in the line direction. 13. A document plate on which a document is placed, a point light source unit in which a plurality of light emitting elements disposed below the document plate are arranged in a row to emit linear light, and a light source reflected by the document. In a line light generating device used for an image reading device having a light receiving element for receiving light and performing photoelectric conversion, a linear light applied to an original is transmitted to a transmission surface through which the original plate is transmitted. A diffraction grating for diffracting light in a line direction, and the diffraction grating is formed so as not to diffract light reflected from a document incident on the light receiving element.