JPH099006A - Lighting device for image input device - Google Patents

Abstract

(57) [Abstract] [Purpose] It enables linear illumination with uniform brightness using light emitting diodes. [Structure] A highly transparent cylindrical light guide portion 31 is provided, and a substrate 11 on which a plurality of light emitting diode elements 15 are arranged is fixed to one end of the light guide portion 31 via a tubular connection member 21. An end reflection member 47 is fixed to the other end of the light guide section 31, and a band-shaped diffuse reflection section 35 for irregularly reflecting light is provided on the surface of the light guide section 31 along the axial direction. Cylindrical reflector around 31
The illuminating device 10 has a structure that includes 41 and has a gap 43 along the axial direction in the reflecting member 41 at a position facing the diffuse reflection part 35.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image input device for illuminating a document to be read using a light emitting diode and reading the document with a line sensor such as a one-dimensional solid-state image sensor to form an image signal representing the image surface of the document. More specifically, the present invention relates to a lighting device of the image input device.

[0002]

2. Description of the Related Art Today, various image input devices such as facsimiles, image scanners, and copying machines that read an image of a document and use it as an image signal are used. Then, the image signal formed by this image input device is transmitted to another device such as a computer for signal processing, or the image signal formed by this image input device is processed by the image input device. Therefore, various kinds of image processing are performed.

In this image input device, a read document is set on a transparent plate called platen glass, and an image reading unit incorporating an illuminating device, a line sensor and the like is moved along the platen glass, or By fixing the image reading unit and moving the original, an image signal representing a two-dimensional image is formed by the one-dimensional solid-state image pickup device which is a line sensor.

In many cases, in this image input device, a fluorescent lamp is used as a light source for illuminating a read document. Further, in an image input device such as a film scanner or a small facsimile which reads a read original having a relatively small width, there are some which use a light emitting diode as a light source of an illumination device. In an image input device using this light emitting diode as a light source of an illumination device, as shown in FIGS. 5 and 6, light emitting diode elements 15 are bonded on a substrate 11 and arranged in a row at a predetermined interval P. There is a device in which a cylindrical transparent member 51 called a lot lens is arranged above the light emitting diode element 15. In many cases,
The transparent member 51 is fixed to the substrate 11 by a supporting member 55 as appropriate.

In the illuminating device in which the transparent member 51 is arranged on the light emitting diode element 15, the light radiated from the light emitting diode element 15 by the transparent member 51 is reflected on the image surface 63 of the read original 60.
The image plane 63 can be brightly illuminated by condensing light on the image plane 63. A line sensor, which is a one-dimensional solid-state image pickup device using a CCD or the like used in an image input device, has a reading range of about 10 μm in width, and is not suitable for an image to be reduced and projected by an optical system. An image pickup unit having a required length as a reading range is used according to the reduction ratio of the optical system. Then, the reading width of the read original 60 is a linear shape having a width of about 0.1 mm on the image surface 63 of the read original 60 when an image is formed on the image pickup means using an optical system such as a lens. Without reading the image directly by bringing the image pickup means such as a line sensor close to the read document 60, the reading width of the document is extremely narrow.

As described above, since the range of the read document 60 that needs to be illuminated with the illumination light by the illumination device is a very elongated linear range, it is more than the required range when using a fluorescent lamp with a large amount of light emission as a light source. The area can be illuminated sufficiently brightly. In a lighting device using a light emitting diode as a light source, the light emitting diode element 15 alone emits less light than a fluorescent lamp.
Light is condensed by using the transparent member 51 so as to increase the illuminance at the reading position in 63, and the substrate 11 on which the light emitting diode elements 15 are arranged is placed in the vicinity of the read original 60 together with the image pickup means which is a line sensor. I was trying to place it.

[0007]

As described above, the fluorescent lamp has an extremely large amount of light emission as compared with the light emitting diode, and is widely used in various image input devices today. However, fluorescent lamps have a shorter lifespan than light emitting diodes,
It requires maintenance and replacement of lighting equipment. Further, in an image input device using an illuminating device using a light emitting diode as a light source, the light emitting diode element may be arranged close to the read document because the light emitting amount of the light emitting diode element is small.
In this case, when the read original becomes large, the light emitting diode elements must be arranged according to the size of the original, and a large number of light emitting diode elements are required.

Even when the light of the light emitting diode is condensed by using the transparent member, the number of the light emitting diode elements is increased in accordance with the size of the read document as the read document becomes larger. Further, when the light emitting diode elements are linearly arranged and the image surface of the read original is directly illuminated by the light emitting diode elements, or when the image surface is illuminated by using a transparent member, as shown in FIG. There is a drawback that the illumination is high near the elements and uneven illumination occurs at the pitch of the interval P between the light emitting diode elements so that the light emitting diode elements are slightly darkened.

[0009]

According to the present invention, a columnar light guide portion having high transparency is used, and a substrate on which a plurality of light emitting diode elements are arranged is provided with a cylindrical connecting member at one end of the light guide portion. It is provided so as to be fixed through, and an end reflection member is attached to the other end of the light guide section, and a band-shaped diffuse reflection section that diffusely reflects light is linearly formed on the surface of the light guide section along the axial direction. Then, a cylindrical reflecting member is provided around the light guide portion, and a gap along the axial direction is formed in the reflecting member at a position facing the diffuse reflecting portion.

In some cases, the outer tubular portion having an inner diameter larger than the outer diameter of the light guiding portion serves as a reflecting member, and the light guiding portion is housed inside the outer tubular portion. In addition, a reflective coating may be formed on the outer surface of the light guide portion, and the reflective coating may be used as a reflective member. The width of the gap formed in the reflecting member is not more than half the circumference of the reflecting member.

The inner surface of the cylindrical connecting member may be a mirror surface. Further, the surface of the substrate may also be a mirror surface. Further, as the light emitting diode element arranged on the substrate, a red light emitting diode element, a green light emitting diode element and a blue light emitting diode element may be mixed.

[0012]

[Operation] According to the present invention, since the substrate on which the plurality of light emitting diode elements are arranged is provided at one end of the cylindrical light guide portion, the light from the light emitting diode element can be incident on the inside of the light guide portion. . And having an end reflection member at the other end of the light guide section,
Moreover, since the cylindrical reflecting member is provided around the light guide portion, it is possible to reflect the light entering the inside of the light guide portion and to advance the light in the axial direction of the light guide portion.

Further, since the strip-shaped diffuse reflection portion is provided on the surface of the light guide portion, the light radiated to the diffuse reflection portion out of the light traveling inside the light guide portion by repeating reflection is diffusely reflected. You can Since the gap of the reflecting member is located at a position facing the diffuse reflection part, a part of the light diffusely reflected by the diffuse reflection part can be radiated to the outside through the gap.

When the outer tube portion is used as the reflecting member, it is easy to store the light guide section inside the reflecting member, and the light leaked from the light guide section to the outside is reflected on the inner surface of the outer tube section. It can be returned to the light guide. When the reflective coating formed on the surface of the light guide section is used as the reflection member, the light incident on the light guide section from the end of the light guide section is exposed to the outside of the light guide section from a place other than the gap. It is possible to reduce the attenuation of light and cause the light to be reflected and propagate in the axial direction of the light guide portion without leaking.

Further, by setting the width of the gap to be less than a half circumference of the reflecting member, the light radiated from the gap to the outside of the light guide portion is deviated from the center of the light guide portion to one side, and the light radiated from the gap. Can be irradiated onto the image surface of the read document. If the inner surface of the connection member is a mirror surface, the light from the light emitting diode element can be effectively guided to the end portion of the light guide portion and can be incident inside the light guide portion.

If the surface of the substrate is a mirror surface, it travels in the axial direction of the light guide portion, is reflected at the other end and returns to the end portion of the light guide portion, and is emitted from the end portion of the light guide portion toward the substrate. The emitted light can be returned to the inside of the light guide portion. If a substrate in which a red light emitting diode element, a green light emitting diode element, and a blue light emitting diode element are arranged in combination is used as the light emitting diode element, it is possible to illuminate the original document with the three primary colors or illuminate the original document with white light.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First illumination device for image input device according to the present invention
In the embodiment, as shown in FIGS. 1 and 2, a cylindrical outer cylinder portion 41 is attached to the substrate 11 by using a cylindrical connecting member 21 which covers the substrate 11 to which the light emitting diode element 15 is bonded. It is fixed substantially vertically, and the cylindrical light guide 31 is provided inside the outer cylinder 41.
Is to be stored. The light guide 31 is a spacer.
It is fixed to the connecting member 21 by 37. In addition, the end of the outer cylindrical portion 41, which is the tip 19 of the illuminating device 10, is sealed with an end reflecting member 47.

A linear gap 43 is formed in the outer cylinder portion 41 along the axial direction, and a linear diffuse reflection portion 35 is provided on the surface of the light guide portion 31 along the axial direction. The light guide section 31 is provided with the outer cylinder section 41 with the position of the gap 43 facing the diffuse reflection section 35.
It is stored and fixed inside. The light guide section 31 is formed into a columnar shape using a material having a high transparency. Further, the diffuse reflection section 35 is formed by applying a coating material to the surface of the light guide section 31 in a band shape that is a straight line in the axial direction of the light guide section 31, or a band-shaped reflection tape that diffusely reflects on the surface or inside. It is formed by linear attachment.

The connecting member 21 has a substantially quadrangular pyramidal cylindrical shape, one of which is a quadrangle matching the shape of the substrate 11 and the other of which is a circular shape matching the outer cylinder portion 41 and the light guide portion 31, and the inner surface is a mirror surface. It is what Therefore, as shown in FIG. 2, the light from each light emitting diode element 15 attached to the surface 13 of the substrate 11 is directly incident on the inside of the light guide portion 31 from the end 33 of the light guide portion 31, or The light is reflected by the inner surface of the tubular connecting member 21 and enters the inside of the light guide portion 31 from the end 33 of the light guide portion 31.

As described above, a part of the light incident on the inside of the highly transparent light guide portion 31 is refracted and transmitted from the surface of the light guide portion 31 to the outside, and a part of the light is reflected on the surface of the light guide portion 31. The light is reflected inside the light guide section 31. Then, the light leaked from the surface of the light guide portion 31 to the outside should be reflected on the inner surface of the outer tubular portion 41 arranged as a reflection member on the outer periphery of the light guide portion 31 and returned to the inside of the light guide portion 31 again. become.

The inner surface of the pipe-shaped outer cylinder portion 41 is preferably mirror-finished. In this way, the light that has entered the inside of the light guide portion 31 from the end portion of the light guide portion 31 is reflected by the surface of the light guide portion 31 and the inner surface of the outer tubular portion 41 that is a reflecting member, and the light guide portion When it reaches the other end of the light guide portion 31, it travels in the axial direction of the light guide portion 31, is reflected by the end reflection member 47, and returns to the inside of the light guide portion 31 in the axial direction of the light guide portion 31.

Of the light that repeats reflection and travels inside the light guide portion 31, the light reflected by the diffuse reflection portion 35 causes irregular reflection with various reflection directions with respect to the incident direction, As shown in FIGS. 2 and 3, a part of the light reflected by the diffuse reflection part 35 is reflected so as to be emitted to the outside of the light guide part 31. Further, since the gap 43 is provided in the cylindrical outer cylinder part 41 at a position facing the diffuse reflection part 35, the light guide part 31 is directed toward the gap 43 in the light diffusely reflected by the diffuse reflection part 35. The light radiated to the outside is radiated from the gap 43 to the outside of the outer cylinder portion 41, and irradiates the read document 60.

The width of the diffusive reflector 35 is such that the light reading original 60 is read.
In order to irradiate the light, the outer circumference of the light guide portion 31 is half or less.
If the width of the diffuse reflection section 35 is increased, the amount of light emitted from the light guide section 31 toward the gap 43 due to irregular reflection can be increased. Further, if the width is made narrower, the light diffusedly reflected in the light traveling in the axial direction inside the light guide portion 31 can be reduced, and the amount of light repeatedly reflected inside the light guide portion 31 can be increased.

The width of the gap 43 formed in the outer cylindrical portion 41 serving as a reflecting member is not more than half the circumference of the outer cylindrical portion 41, and the gap 43 in the light radiated from the surface of the light guide portion 31 to the outside is defined by the gap 43. All the transmitted light irradiates the surface of the read document 60, and the light emitted from the surface of the light guide section 31 to the outside in the direction in which the read document 60 is not irradiated is reflected by the inner surface of the outer tube section 41 and guided. Try to set it back to 31. Further, by setting the outer cylinder portion 41 to have a half circumference or more, it is possible to prevent light from the outside from entering the light guide portion 31 and prevent it from hitting the illuminated portion of the read document 60 by the illumination device 10. it can.

Therefore, if the widths of the diffuse reflection part 35 and the gap 43 are narrowed, the light which is repeatedly reflected in the light guide part 31 and the like is emitted from the linear gap 43 to the outside, and the light is emitted from the gap 43. The intensity of light applied to the image surface 63 of the read document 60 can be made more uniform as a whole. The reading width on the document is about 0.1 mm, but if tolerances such as mechanical displacement between the reading position and the illumination range are taken into consideration,
It is preferable to set the width of the diffuse reflection portion 35 and the width of the gap 43 so that the illumination width on the document is about several mm.

Further, in the above embodiment, the outer cylindrical portion is used as the reflecting member.
Although 41 is used, as shown in FIG.
A band-shaped diffuse reflection part 35 is formed on a part of 31 and a reflection film 45 such as aluminum vapor deposition is formed so as to form an opening as a gap 43 at a position facing the diffuse reflection part 35 and a reflection member. I have something to do. The second embodiment is a diffuse reflector.
The light guide portion 31 having the surface 35 and the reflection film 45 formed thereon is fixed to the tip of the connecting member 21 by using a spacer 37 and the like as in the first embodiment shown in FIG. On the end reflection member
If 47 is fitted, the end portion 33 of the light guide portion 31 is similar to the above-mentioned embodiment.
It is possible to reflect the light incident from the inside of the light guide portion 31 and to advance it, and irradiate a part of the light diffusely reflected by the diffuse reflection portion 35 to the outside through the gap 43.

As described above, the reflective film 45 is formed on the surface of the light guide section 31.
If the reflecting member is formed, the light can be repeatedly reflected inside the light guide section 31 to reduce light attenuation, and the lighting device 10 can be made thin and downsized easily. However, when the reflecting member is formed by using the outer tubular portion 41, it is possible to prevent the light guiding portion 31 and the reflecting member that is the inner surface of the outer tubular portion 41 from being easily scratched, and the lighting device 10 can be easily handled. Is what you can do.

In the embodiment shown in FIGS. 1 and 2, the substrate 11 has a rectangular shape that is large in the vertical and horizontal directions with respect to the diameter of the light guide section 31.
Using a pyramid-shaped connecting member 21 in which the position of the base portion 23 is enlarged so as to connect the substrate 11 and the light guide section 31 by using, the length of the substrate 11 in the vertical direction is equal to that of the light guide section 31. The diameter may be substantially equal to the diameter, and the lateral length of the substrate 11 may be larger than the diameter of the light guide portion 31.

In this case, as the connecting member 21, two substantially parallel plate-shaped upper and lower plate portions and a base portion 23 are formed so that the distance between them is wide. The shape may be a tubular shape close to a quadrangular pyramid formed by the section. In this case, the connection member 21 can be easily formed and manufactured, and the height of the lighting device 10 can be reduced. The substrate 11 is not limited to a rectangle but may be a circle. In this case, the connection member 21 has a conical cylindrical shape.

Further, the light emitting diode elements 15 are arranged on the inner surface 13 of the substrate 11 so as to be as close to each other as possible, but the gaps between the light emitting diode elements 15 are appropriately formed with a mirror-like reflective coating to form a light guiding portion. It is preferable that the light leaked from the end 33 of 31 is reflected and returned to the light guide 31 again. The substrate
An appropriate heat dissipation plate 17 is provided on the outer surface of 11 to dissipate the heat generated by the densely packed light emitting diode elements 15.

Further, the light emitting diode element 15 is not limited to the one that emits light of a specific wavelength according to the characteristics of the image pickup device in the image input device. That is, the red light emitting diode element, the green light emitting diode element, and the blue light emitting diode element may be mixed and used.
In this case, the lighting device 10 can illuminate with white light, and can also turn on the light emitting diode element 15
By limiting the above, it becomes possible to illuminate with the three primary colors of red light, green light and blue light.

[0032]

EFFECTS OF THE INVENTION Since the present invention is a lighting device using a light emitting diode element, it has a long life and enables quick and stable lighting, and a part of light repeatedly reflected inside the light guide portion is emitted from the gap. Therefore, linear illumination with uniform illuminance can be achieved. Further, in the invention described in claim 2, since the light guide part is housed inside the outer cylinder part 41, the light guide part and the outer cylinder part are attached to the connecting member to facilitate the manufacture,
The outer cylinder portion can block ambient light and perform good illumination.

The invention described in claim 3 uses the reflective coating formed on the surface of the light guide section as the reflecting member, and therefore can be easily manufactured by attaching the light guide section to the connecting member. The diameter of the device can be reduced, and the lighting device can be made compact and lightweight. Further, according to the invention described in claim 4, it is possible to irradiate the reading original with all of the light emitted from the gap, and to efficiently irradiate the original with the light emitted from the light emitting diode element.

According to the invention described in claim 5, the light emitted from the light emitting diode element can be guided to the inside of the light guide portion without wasting, and the invention described in claim 6,
The light leaked from the end of the light guide is returned to the inside of the light guide,
Light can be efficiently emitted from the gap. The invention described in claim 7 is an illuminating device capable of illuminating with white light or three primary colors, and is suitable for forming color image data.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view showing a first embodiment of a lighting device according to the present invention.

FIG. 2 is a vertical cross-sectional front view of the first embodiment of the lighting device according to the present invention.

FIG. 3 is a vertical sectional side view in the first embodiment of the lighting device according to the present invention.

FIG. 4 is a vertical cross-sectional side view showing another embodiment of the lighting device according to the present invention.

FIG. 5 is a side view showing an example of a conventional lighting device.

FIG. 6 is a front view showing an example of a conventional lighting device.

FIG. 7 is a diagram showing an illuminance distribution in a conventional lighting device.

[Explanation of symbols]

 10 Lighting Device 11 Substrate 13 Substrate Surface 15 Light Emitting Diode Element 17 Heat Dissipating Plate 19 Tip 21 Connection Member 23 Base 25 Tip 31 Light Guide 33 End 35 Diffuse Reflector 37 Spacer 41 Outer Cylinder 43 Gap 45 Reflective Film 47 Edge Reflection Member 51 Transparent member 55 Support member 60 Read original 63 Image surface

Claims (7)

[Claims] 1. A columnar light guide portion having high transparency is provided, and a substrate on which a plurality of light emitting diode elements are arranged is fixed to one end of the light guide portion through a tubular connecting member, An end reflection member is fixed to the other end of the light section, and a band-shaped diffuse reflection section that diffusely reflects light is linearly provided along the axial direction on the surface of the light guide section. A lighting device for an image input device, characterized in that it has a cylindrical reflecting member around its periphery, and has a linear gap along the axial direction in the reflecting member at a position facing the diffuse reflection portion. apparatus. 2. The pipe-shaped outer cylinder having an inner diameter larger than the outer diameter of the light guide is used as the reflection member, and the light guide is housed inside the outer cylinder. The lighting device for an image input device according to claim 1. 3. The illumination device for an image input device according to claim 1, wherein a reflective coating is formed on an outer surface of the light guide portion, and the reflective coating serves as the reflecting member. 4. The illumination for an image input device according to claim 1, wherein a width of the gap formed in the reflecting member is equal to or less than a half circumference of the reflecting member. apparatus. 5. The illumination device for an image input device according to claim 1, wherein an inner surface of the connection member is a mirror surface. 6. The illumination device for an image input device according to claim 1, wherein the surface of the substrate is a mirror surface. 7. The light emitting diode element arranged on the substrate is a mixture of a red light emitting diode element, a green light emitting diode element and a blue light emitting diode element. An illumination device for an image input device as described above.