JP2001119530A - Linear image sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a linear image sensor that can realize a long focal depth, miniaturization, thinning and low power consumption. SOLUTION: The linear image sensor consists of a light source section 14 that includes an LED array where a plurality of LEDs 16 are arranged in a line, an optical reflection plate 18 that is placed on each LED 16 to limit the emitting direction of the light source section 14 in a prescribed direction, a plurality of micro lenses 11 arranged in a line, a light guide array 10 consisting of a plurality of light guides 10a placed on each micro lens 11, a line sensor 12 detecting a reflected light led from the light guide array 10, an enclosure 15 to fix the components above, and a glass plate 19 that protects the inside of the enclosure or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a one-dimensional image sensor device used for a scanner, a facsimile, etc., for reading an image of a document line by line and converting it into an electric signal.

[0002]

2. Description of the Related Art In recent years, with the spread of home-use facsimile, there has been a demand for a one-dimensional image sensor unit for converting image information of a document into an electric signal with higher performance, smaller size and lower price. When such a reading unit is reduced in size, it can be incorporated into a handy scanner. The handy scanner has an advantage that it can read not only a manuscript of a flat shape but also a book in a spread state. in this case,
When the book becomes thicker, the handy scanner hardly comes into close contact with the paper in the vicinity of the binding portion. Therefore, a handy scanner with a large depth of focus is demanded.

As a conventional one-dimensional image sensor, a) the reflected light from the original surface is turned back by a mirror, and the reflected light from the main scanning line on the original surface is collected using a single imaging lens;
A lens-reduced optical image sensor that forms an image on the photoelectric conversion element, or b) a contact image that condenses reflected light from the main scanning line on the original surface with a selfoc lens array and forms an image on the photoelectric conversion element at the same magnification. Sensors, etc. In the former lens-reduced optical image sensor, the object-side space of the imaging lens becomes large, and it is difficult to reduce the size. The latter contact type image sensor is not suitable for reading an original having an uneven shape because the depth of focus is small as a characteristic of the selfoc lens array itself.

[0004] As a related prior art, Japanese Patent Laid-Open No. 7-30 is disclosed.
No. 1730, JP-A-9-37038, JP-A-10-7
No. 0259, there is proposed an optical waveguide reduced image sensor in which reflected light from a document is condensed by a microlens array and further reduced and guided to a photoelectric conversion element using an optical waveguide array. This optical waveguide reduced image sensor has the advantage that the depth of focus is increased by the microlens and the miniaturization is facilitated by the optical waveguide array, making it suitable for incorporation into a handy scanner.

FIG. 6 is a sectional view showing an example of a conventional contact type image sensor. LED (l
ight emitting diode) array 64, selfoc lens array 61, photoelectric conversion element 62
A glass plate 66 is attached to the opening 5, and the dimension in the longitudinal direction (perpendicular to the paper surface) is substantially the same as the width of the document. When the LED array 64 irradiates light along the main scanning line on the document surface, the reflected light from the main scanning line is condensed by the selfoc lens array 61 and forms an image at the same size on the photoelectric conversion element 62.

FIG. 7 is a cross-sectional view showing an example of a conventional optical waveguide reduced image sensor. Inside the housing 75,
An LED array 74, a microlens array 71, an optical waveguide array 70, and a photoelectric conversion element 72 are attached, a glass plate 76 is attached to an opening of a housing 75, and a dimension in a longitudinal direction (perpendicular to the paper surface) is substantially the same as the width of the document. become. LE
When the D array 74 irradiates light along the main scanning line on the document surface, the reflected light from the main scanning line is condensed by the microlens array 71 and further reduced and guided to the photoelectric conversion element 72 by the optical waveguide array 70. . For example, when reading the width of a B4 size document at a resolution of 200 dpi (dots per inch), the size of the photoelectric conversion element 72 is 28.7 mm.

[0007] The irradiation light of the LED array 74 is distributed in a range from a dashed line a to a dashed line c around the dashed line b in FIG.
It is emitted with a certain spread angle. When the document surface is at a position X that is in close contact with the glass plate 76, the document reading position x
Is reflected by the microlens array 71 and is converted into one-dimensional image information by the photoelectric conversion element 72. The irradiation direction of the LED array 74 is set so as to ensure a sufficient contrast in the read image, and the irradiation angle formed by the normal direction N of the document surface and the irradiation light center (dashed line b) is set to about 45 °. You. LED array 74
Is composed of a plurality of chip-type LEDs arranged at a pitch of about 5 mm to 10 mm along the main scanning direction of the image sensor (perpendicular to the paper surface). The distance from the LED to the LED is about 5
mm to about 10 mm.

[0008]

In the conventional image sensor, if the image sensor is far from the document surface, it becomes difficult to read the document properly due to uneven distribution of irradiation light and defocus of the image forming optical system. For example, in FIG.
If the document surface is located at a position Y distant from the original, the dashed line c, which is the limit of the irradiation area, and the document surface intersect at the reading position y, which causes a decrease in illuminance and a defocus, but the reading of the document itself is possible. However, when the document surface is further away from the glass plate 76 and located at the position Z, the reading of the document becomes impossible because the illuminance at the reading position z is insufficient.

As a countermeasure, (1) a structure in which an LED array having a small directivity and a large irradiation angle is used to arrange an LED array capable of irradiating as much as possible, (2) an LED array for short-range irradiation and an LED for long-range irradiation A structure in which the array is arranged and (3) a structure in which a light guide plate for correcting the illuminance distribution is installed on the front surface of the LED array, and the like can be considered.

However, in the structure (1), when the spread angle of the illuminating light increases, the illuminance greatly changes in accordance with the change in the position of the original document. Problems such as a decrease in utilization efficiency and a decrease in the contrast of the read image occur because the irradiation angle with respect to the document surface becomes closer to the vertical as the document surface is farther away. In the structure (2), since the number of components of the LED array increases, there is a concern about an increase in product cost and an increase in power consumption, and the size of the entire image sensor is increased. In the structure of (3), the light guide plate requires an extremely complicated surface shape, and the mounting accuracy of the light guide plate becomes strict. Therefore, the cost of parts and assembly increases, and the space of the light source unit becomes large.

An object of the present invention is to achieve a long focal depth,
An object of the present invention is to provide a one-dimensional image sensor device that can be reduced in size, thickness, and power consumption.

[0012]

According to the present invention, there is provided a light source unit for irradiating light along a main scanning line on a document surface, and a unit for detecting reflected light from the main scanning line and converting the reflected light into an electric signal. A photoelectric conversion element, and an irradiation direction limiting member interposed between the light source unit and the document for limiting the irradiation direction of the light source unit to a predetermined direction.

According to the present invention, the irradiation distribution of the light source unit can be adjusted to a desired distribution by providing the irradiation direction restricting member for restricting the irradiation direction of the light source unit to a predetermined direction. For example, by blocking or attenuating the irradiation light incident in a direction close to the direction perpendicular to the document surface, a) the scattered light incident on the photoelectric conversion element can be reduced, so that the contrast of the read image can be maintained high. Since the distribution directivity can be relaxed and corrected to a distribution close to non-directivity, even if the distance from the sensor body to the document surface changes, the change in illuminance on the document surface is reduced, and the depth of focus can be increased.

According to the present invention, there is provided a light source for irradiating light along a main scanning line on a document surface, a plurality of microlenses for condensing light reflected from the main scanning line, and a plurality of microlenses. An optical waveguide array composed of a plurality of optical waveguides for individually guiding the emitted light, a photoelectric conversion element array for detecting reflected light guided by the optical waveguide array and converting the reflected light into an electric signal, and a light source unit And a radiation direction restricting member for restricting the radiation direction of the light source unit to a predetermined direction.

According to the present invention, the depth of focus of the optical system is increased by using a microlens, and the size of the optical system is reduced by using an optical waveguide array.

Further, by providing an irradiation direction restricting member for restricting the irradiation direction of the light source unit to a predetermined direction, the irradiation distribution of the light source unit can be adjusted to a desired distribution. For example, by blocking or attenuating the irradiation light incident in a direction close to the direction perpendicular to the document surface, a) the scattered light incident on the photoelectric conversion element can be reduced, so that the contrast of the read image can be maintained high. Since the distribution directivity can be relaxed and corrected to a distribution close to non-directivity, even if the distance from the sensor body to the document surface changes, the change in illuminance on the document surface is reduced, and the depth of focus can be increased.

Further, according to the present invention, the irradiation direction restricting member includes:
It is characterized in that irradiation light whose irradiation angle is less than 30 ° with respect to the normal direction of the document surface is blocked.

According to the present invention, the original surface is illuminated with light obliquely incident at 30 ° or more by blocking the irradiation light having an irradiation angle of less than 30 ° with respect to the normal direction of the original surface. High contrast can be maintained.

Further, in the present invention, the irradiation angle of the irradiation light defined by the irradiation direction restricting member is in the range of 30 ° to 60 ° with respect to the normal direction in a plane including the normal direction and the main scanning direction of the document surface. And in the plane including the normal direction and the sub-scanning direction of the document surface,
It is characterized by a range of 0 ° or less.

According to the present invention, in the plane including the normal direction and the main scanning direction of the document surface, 45
Since the document surface is illuminated with light obliquely incident at an irradiation angle of ± 15 °, the contrast of the read image can be kept high.

The original surface is illuminated with light incident at an irradiation angle of 0 ° to 30 ° with respect to the normal direction in a plane including the normal direction and the sub-scanning direction of the original surface. The change in illuminance on the document surface is reduced even if the distance to the original fluctuates, and the depth of focus can be increased. Furthermore, since the position of the light source unit can be made closer to the photoelectric conversion element in a plane including the normal direction and the sub-scanning direction of the document surface, the sensor main body can be thinned in the sub-scanning direction.

Also, in the present invention, the light source unit is constituted by an LED array composed of a plurality of LEDs, and the irradiation direction restricting member is constituted by a plurality of light reflecting plates provided close to each LED. Features.

According to the present invention, by arranging a plurality of LEDs and light reflecting plates in an array, it is possible to realize high-contrast line illumination with a small incident component perpendicular to the document surface at a small size and at low cost.

Further, the present invention is characterized in that the LED has a light emitting chip sealed in a resin mold, and the irradiation direction limiting member is formed of a light reflecting plate integrally formed with the resin mold. .

According to the present invention, the number of parts is reduced and the cost is reduced by integrally forming the light reflecting plate with the resin mold.

Further, in the present invention, the LED has a light emitting chip sealed in a resin mold, and the irradiation direction limiting member is constituted by a light refracting portion formed by forming the resin mold into a concave shape. I do.

According to the present invention, since the irradiation direction can be restricted only by forming the resin mold in a concave shape, the number of parts is reduced and the cost is reduced.

Further, in the present invention, in the LED, the light emitting chip is sealed in a resin mold, the resin mold is formed in a cylindrical lens shape, and the irradiation light directivity is in the direction perpendicular to the LED array rather than in the LED array direction. Is small.

According to the present invention, the irradiation light directivity of the LED is elongated in the main scanning direction, so that the light use efficiency is improved and the power consumption of the light source unit is reduced.

[0030]

FIG. 1 is a sectional view taken along a main scanning direction of a structure according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along a sub-scanning direction. The one-dimensional image sensor device includes: a light source unit 14 including an LED array in which a plurality of LEDs 16 are arranged in a line;
A light reflecting plate 18 provided for each of the optical waveguides, a plurality of micro-lenses 11 arranged in a line, a plurality of optical waveguides 10a provided for each of the micro-lenses 11, an optical waveguide array 10; , A line sensor 12 for detecting the reflected light guided by the above, a housing 15 for fixing these components, a glass plate 19 for protecting the inside of the housing 15, and the like.

The light source unit 14 has an LE
D16 is attached at a constant pitch to form an LED array. The light emitted from each LED 16 forms an elongated line illumination along the main scanning direction of the document surface. As shown in FIG. 2, a pedestal is formed inside the housing 15 so as to be oblique to the normal direction N of the document surface, and the substrate 17 of the light source unit 14 is fixed to this pedestal. Each LED
Light 16 is applied obliquely to the normal direction N of the document surface. When the main scanning line on the document surface is illuminated, the intensity of the reflected light changes according to the document image.

The microlens 11 is integrally fixed to the incident surface of the optical waveguide 10a, condenses the reflected light from the main scanning line, and transmits it to the corresponding optical waveguide 10a. As shown in FIG. 2, the optical axes of the microlens 11 and the optical waveguide array 10 are fixed inside the housing 15 such that they substantially coincide with the normal direction N of the document surface.

The optical waveguide array 10 includes a micro lens 11
The light condensed by the above is individually guided and transmitted to the line sensor 12. The pitch of the optical waveguide 10a changes on the incident side and the output side of the optical waveguide array 10, and constitutes a reduced imaging optical system in which the output side pitch is smaller than the incident side pitch.

The line sensor 12 is constituted by a linear CCD sensor or the like having a plurality of light receiving pixels, detects light guided by the optical waveguide array 10, converts the light into an electric signal, and outputs the signal as a read signal of a document image. .

For example, if the width of a B4 size document is
When reading at 00 dpi (dots per inch), the line length of the microlens 11 substantially matches the B4 size (256 mm), and the size of the line sensor 12 becomes 28.7 mm due to the reduced light guide of the optical waveguide array 10. Also, the pitch on the incident side of the optical waveguide 10a is 125 μm, and the pitch on the exit side is 1
4 μm, and the light receiving pixel size of the line sensor 12 is 1
2 μm × 14 μm, the light receiving pixel pitch is 14 μm, and the number of light receiving pixels is 2048. The diameter of the micro lens 11 is 120 μm, the numerical aperture NA is 0.210, and the micro lens 11 has a pitch of 125 μm, which is the same as the pitch on the incident side of the optical waveguide 10a.
Forty-eight are formed. The microlens 11 and the optical waveguide array 10 are simultaneously formed of the same material, for example, PMMA by integral injection molding.

Regarding the method of manufacturing the optical waveguide array 10,
After forming a micro-groove having a cross section of 8 μm square on the substrate by injection molding of the array substrate, an ultraviolet curable resin as a core material is dropped into the micro-groove, and unnecessary resin protruding from the micro-groove is removed by a squeegee method. Next, the resin in the fine groove is cured by ultraviolet irradiation to form a core portion of the optical waveguide. Thereafter, an ultraviolet curable resin, which is a clad material, is dropped so as to cover the core portion, and is cured by irradiation with ultraviolet light to form a clad portion of the optical waveguide.

Each microlens 11, optical waveguide 10
a and the light receiving pixels of the line sensor 12 are connected in a one-to-one correspondence, and one of these systems is in charge of one read pixel in the main scanning line on the document surface. When light of another system is mixed via the microlens 11, the optical waveguide 10a, and the like and reaches the line sensor 12, crosstalk between pixels occurs to deteriorate the resolution.

As a countermeasure, it is preferable that the numerical aperture of the microlens 11 and the numerical aperture of the optical waveguide 10a are made substantially the same, so that light that cannot be condensed by the microlens 11 is not guided by the optical waveguide 10a.
Crosstalk between pixels can be prevented. In addition, since the light condensed by the microlens 11 can be guided through the optical waveguide 10a, the transmission loss of the light is reduced. In addition, even when the document surface is far away, the light can be efficiently collected and guided. Readable distance, that is, the depth of focus can be increased. For example, assuming that the refractive index of the core portion of the optical waveguide 10a is 1.506 and the refractive index of the cladding portion is 1.492, the numerical aperture of the optical waveguide 10a is 0.205, and the numerical aperture of the microlens 11 is approximately 0.210. Matches.

FIG. 3 is an explanatory diagram showing the irradiation direction of the light source unit 14. As shown in FIG. LED 16 is a chip type LED with side emission
And is linearly arranged on the substrate 17 at a pitch of about 5 mm to 10 mm, and emits light substantially parallel to the surface of the substrate 17 and along the lateral direction. The distance between the LED 16 and the document is set to about 5 mm to 10 mm to ensure uniform illuminance in the main scanning direction. Chip type LED
16 is approximately ± in the main scanning direction with the LED front direction as the center.
Emit light in a range of 60 °.

The light reflecting plate 18 has a structure in which two rectangular reflecting surfaces are formed into a triangle having an apex angle of about 60 °, and the substrate 17 has an apex angle located in front of the LED 16.
Is fixed on the The light reflection plate 18 is positioned between the LED 16 and the document so as to block direct light having an irradiation angle of less than 30 ° with respect to the normal direction N of the document surface and to reflect sideways.

Therefore, as shown in FIG. 3, the area where one LED 16 irradiates the original is an area L of about 30 ° to about 60 ° on the left side and an area R of about 30 ° to about 60 ° on the right side. . The region D between the regions L and R is shielded from light by the nearest light reflection plate 18, but the adjacent LED 16
Illuminated by illumination light from

With this configuration, the document surface is illuminated with light obliquely incident at an irradiation angle of 45 ° ± 15 ° with respect to the normal direction of the document surface in a plane including the normal direction and the main scanning direction of the document surface. Therefore, the contrast of the read image can be kept high.

Next, referring to FIG. 2, the chip type L in the plane including the normal direction and the sub-scanning direction of the original surface will be described.
In the ED 16, the light emitting chip is sealed in a resin mold, the shape of the resin mold is formed in a cylindrical lens shape, and the irradiation light directivity is set to be smaller in the LED array orthogonal direction than in the LED array direction. Therefore, the light emitted from the chip is condensed in the sub-scanning direction by the action of the cylindrical lens, and emits light in a range of ± 15 ° in the sub-scanning direction with the LED front direction as the center.

Irradiation light incident on the document surface is distributed in a range from a dashed line a to a dashed line c around the optical axis (dashed line b). The incident angle of the optical axis with respect to the normal direction N of the document surface can be adjusted by the inclination of the pedestal of the housing 15. Therefore, by setting the irradiation angle of 0 ° to 30 ° with respect to the normal direction N in the plane including the normal direction N and the sub-scanning direction of the document surface, the contrast of the read image can be maintained high, and the sensor main body can be maintained. Even if the distance to the document surface changes, the change in illuminance on the document surface is reduced, and a longer focal depth is achieved.

Next, the operation will be described. The light source unit 14 irradiates the original surface, and the reflected light from the original surface is condensed by the microlens 11, further guided by the optical waveguide array 10, and enters the line sensor 12. Here, as shown in FIG. 2, when the document surface is at the position X where the document surface is in close contact with the glass plate 19, the position where the broken line a and the position X intersect is the document reading position x, and an appropriate illuminance is obtained. The reflected light from the reading position x is condensed by the microlens 11 and converted into one-dimensional image information by the line sensor 12.

Even when the document surface is at the position Y 5 mm away from the glass plate 19, the position where the optical axis (dashed line b) and the position Y intersect is the document reading position y, so that an appropriate illuminance can be obtained. The reflected light from the reading position y is the micro lens 1
The light is condensed by 1 and is converted into one-dimensional image information by the line sensor 12.

Even when the original surface is at the position Z which is 10 mm away from the glass plate 19, the position where the broken line c and the position Z intersect is the original reading position z, and an appropriate illuminance is obtained. Is reflected by the microlens 11 and is converted into one-dimensional image information by the line sensor 12.

As described above, even when the document surface is far from the sensor main body, a sufficient illuminance can be secured at the document reading position, so that the sensor has a long focal depth.

In the above description, an example of the configuration of an optical waveguide reduced image sensor combining a microlens and an optical waveguide array has been described. However, the present invention is directed to a lens reduced optical image combining a folding mirror and a single imaging lens. The present invention can be applied to a sensor. In this case, the present invention is effective because the depth of focus of the imaging lens system is long.

The present invention is also applicable to a contact type image sensor using a selfoc lens array. In this case, an image sensor having a long depth of focus is being developed by improvement of the selfoc lens array. The overall size can be reduced in thickness and size by the combination of.

FIG. 4 is a configuration diagram showing another example of the light source unit 14. As shown in FIG. The chip type LED 46 includes a light emitting chip 47
The light reflecting plate 48 having a triangular shape is sealed in a resin mold. By integrally forming the light emitting chip 47 and the light reflecting plate 48, the positional accuracy between them is improved, the variation of the irradiation light distribution is reduced, the light source characteristics are stabilized, and the number of parts is reduced, so that the light source unit is reduced. 14
Can be easily manufactured. The light emitting surface 4 of the resin mold
The shape of 6a may be formed in a cylindrical lens shape, whereby a light condensing action in the sub-scanning direction is obtained.

FIG. 5 is a configuration diagram showing still another example of the light source unit 14. As shown in FIG. The chip type LED 56 has a light emitting chip 57 sealed in a resin mold, and the light emitting surface of the resin mold is formed in a concave shape. As shown in FIG. 5, the light exit surface is composed of a plurality of planes having different angles with respect to the LED optical axis.
8 and the outside thereof becomes the light refraction surface 59. When the light from the light emitting chip 57 reaches the light reflecting surface 58, the incident angle becomes larger than the critical angle, so that the light is totally reflected sideways. When the light from the light emitting chip 57 reaches the light refraction surface 59, it passes through according to the law of refraction and is emitted to the outside. Therefore, by appropriately setting the angles and the sizes of the light reflecting surface 58 and the light refracting surface 59, the irradiation angle on the document surface can be adjusted.

By integrally forming the light reflecting surface 58 and the light refracting surface 59 on the resin mold of the light emitting chip 57, the positional accuracy between the two is improved, and the distribution of the irradiation light is reduced and the light source characteristic is reduced. Is stabilized, and the number of components is reduced, so that the light source unit 14 is easily manufactured. The light emitting surface of the resin mold may be formed in a cylindrical lens shape, whereby a light condensing action in the sub-scanning direction is obtained.

In the above description, a configuration example using an LED array as the light source unit 14 has been described. However, a combination of a cathode ray tube and a light reflecting plate can be used as a light source of a one-dimensional image sensor.

[0055]

As described above in detail, according to the present invention, the irradiation distribution of the light source can be adjusted to a desired distribution by providing the irradiation direction restricting member for restricting the irradiation direction of the light source to a predetermined direction. it can. For example, by blocking or attenuating the irradiating light incident in a direction near perpendicular to the document surface, a) since the scattered light incident on the photoelectric conversion element can be reduced, the contrast of the read image can be kept high, and further,
b) Since the directivity of the irradiation distribution can be relaxed and corrected to a distribution close to non-directivity, even if the distance from the sensor body to the document surface fluctuates, the illuminance change on the document surface is reduced, and the depth of focus can be increased. Can be

Further, the depth of focus of the optical system is increased by using the microlenses, and the size of the optical system is reduced by using the optical waveguide array.

Further, by using the irradiation direction restricting member to block irradiation light having an irradiation angle of less than 30 ° with respect to the normal direction of the document surface, the document surface is illuminated with light obliquely incident at 30 ° or more. Thus, the contrast of the read image can be kept high.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a configuration according to an embodiment of the present invention, taken along a main scanning direction.

FIG. 2 is a cross-sectional view of the configuration of the embodiment of the present invention, taken along a sub-scanning direction.

FIG. 3 is an explanatory diagram showing an irradiation direction of a light source unit 14.

FIG. 4 is a configuration diagram showing another example of the light source unit 14.

FIG. 5 is a configuration diagram showing still another example of the light source unit 14.

FIG. 6 is a cross-sectional view illustrating an example of a conventional contact image sensor.

FIG. 7 is a cross-sectional view illustrating an example of a conventional optical waveguide reduced image sensor.

[Explanation of symbols]

 Reference Signs List 10 optical waveguide array 10a optical waveguide 11 micro lens 12 line sensor 14 light source unit 15 housing 16, 46, 56 LED 17 substrate 18 light reflecting plate 19 glass plate 47, 57 light emitting chip 48 light reflecting plate 58 light reflecting surface 59 light refraction surface

Claims (8)

[Claims] 1. A light source unit for irradiating light along a main scanning line on a document surface, a photoelectric conversion element for detecting reflected light from the main scanning line and converting the reflected light into an electric signal, and a light source unit A radiation direction restricting member interposed between the light source unit and the document, for restricting the radiation direction of the light source unit to a predetermined direction. 2. A light source unit for irradiating light along a main scanning line on a document surface, a plurality of microlenses for condensing reflected light from the main scanning line, and light condensed by each microlens. An optical waveguide array comprising a plurality of optical waveguides for individually guiding light, a photoelectric conversion element array for detecting reflected light guided by the optical waveguide array and converting the reflected light into an electric signal, a light source unit, and a document. And a radiation direction restricting member for restricting the radiation direction of the light source section to a predetermined direction. 3. The one-dimensional image sensor device according to claim 1, wherein the irradiation direction restricting member blocks irradiation light having an irradiation angle of less than 30 ° with respect to a normal direction of a document surface. 4. The irradiation angle of the irradiation light defined by the irradiation direction limiting member is 30 ° to 60 ° with respect to the normal direction in a plane including the normal direction and the main scanning direction of the document surface.
4. The one-dimensional image sensor device according to claim 3, wherein the angle is within a range of 30 degrees with respect to the normal direction in a plane including the normal direction and the sub-scanning direction of the document surface. 5. The light source unit comprises an LED comprising a plurality of LEDs.
The one-dimensional image sensor according to any one of claims 1 to 4, wherein the one-dimensional image sensor is configured by an array, and the irradiation direction limiting member is configured by a plurality of light reflection plates provided in proximity to each LED. apparatus. 6. The LED according to claim 5, wherein the light emitting chip is sealed in a resin mold, and the irradiation direction restricting member is formed of a light reflecting plate integrally formed with the resin mold. A one-dimensional image sensor device according to claim 1. 7. The LED according to claim 1, wherein the light emitting chip is sealed in a resin mold, and the irradiation direction restricting member is formed of a light refracting portion having the resin mold formed in a concave shape. 5. The one-dimensional image sensor device according to 5. 8. The LED has a light emitting chip sealed in a resin mold, the resin mold is formed in a cylindrical lens shape, and the irradiation light directivity is lower than the LED array direction.
6. The one-dimensional image sensor device according to claim 5, wherein the direction in the direction perpendicular to the ED array is smaller.