JPH04112557U - Image reading device light source - Google Patents

Abstract

(57) [Summary] [Purpose] The light intensity distribution when the light reflected from the document surface is projected onto the image sensor through the lens becomes uniform, and a lens with relatively strong power, that is, a short focal length, can also be used. To shorten the distance between a document and an image sensor. [Structure] The light source 15 includes a flexible substrate 10 on the surface of which a plurality of light emitting elements 9 are arranged at equal intervals, and a metal plate 11 that is bonded to the back surface of the flexible substrate 10 to hold the flexible substrate 10 in a curved state. Consists of.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

The present invention relates to a light source for an image reading device used in an image scanner, etc. It is something.

0002

[Conventional technology]

Conventionally, image scanners etc. read images on the surface of large documents, for example. When taking images, an image reading device as shown in FIG. 5 is used. That is, the image reading device 1 uses the paper feed roller 2 to move the original 3 onto a plate such as a glass plate. While moving relatively in one direction (direction of arrow X in Figure 5) on Latin 4, Line-shaped illumination by bar-shaped light source 5 extending in the direction perpendicular to the moving direction (X direction) Light is irradiated onto the original 3, and the light reflected by the original 3 is sent to the CCD via the lens 6. etc., and repeat the above operation as the document 3 moves. The system now reads image information on the surface of the document.

0003

[Problem that the idea aims to solve]

However, the bar-shaped light source 5, as shown in FIG. Since it was made up of light emitting elements 9 such as LEDs arranged at equal intervals, The light intensity distribution of the generated illumination light on the document surface is as shown in Figure 7. Although the light is relatively uniform, the reflected light from the document surface is projected onto the image sensor 7 through the lens 6. Due to the convergence effect of the lens 6, the light intensity distribution when shadowed is centered in the center as shown in FIG. There is a problem in that the distribution is strong in some parts and weak in both ends, that is, the distribution becomes non-uniform. This tendency becomes more pronounced as the power of the lens 6 becomes stronger, so there is an imbalance in the light intensity distribution. In order to make the uniformity as small as possible, the lens 6 should have a weak power, that is, a focal length As a result, the distance d between the document 3 and the image sensor 7 has to be relatively long. It may be difficult to make the entire device more compact due to the length of the If the optical path is bent by bending the optical path, a mirror, etc. will be required, which increases manufacturing costs. There was a problem that it became.

0004 In view of the above-mentioned problems, the present invention was designed to allow light reflected from the document surface to pass through the lens and onto the image sensor. The light intensity distribution becomes uniform when projected onto Image capture that allows the use of lenses with short focal lengths and shortens the distance between the document and the image sensor. It is intended to provide a light source for the reading device.

[0005]

[Means to solve the problem]

In order to achieve the above object, the light source of the image reading device according to the present invention includes: A flexible substrate with multiple light emitting elements arranged at equal intervals on its surface, and this flexible substrate. It is adhered to the back side of the flexible substrate to hold the flexible substrate in a curved state. It is characterized by being made of sheet metal.

[0006]

[Effect]

According to the above configuration, there is no difference in the intensity distribution of the light projected onto the image sensor through the lens. By bending the flexible substrate in a direction that eliminates the uniformity, Even if a relatively powerful lens is used, a uniform light intensity distribution can be obtained on the image sensor. Ru.

[0007]

【Example】

Hereinafter, based on the illustrated embodiment, the same members as in the conventional example described above are designated by the same reference numerals. The present invention will now be explained in detail. FIG. 1 is a side view of an embodiment of a light source 15 of an image reading device according to the present invention. 10 is a flexible board on which a plurality of light emitting elements 9 such as LEDs are arranged at equal intervals. The flexible substrate 11 is bonded to the back surface of the flexible substrate 10. It is a sheet metal that holds the metal in a curved state.

[0008] Since this embodiment is configured as described above, the irradiated light is As shown in Figure 2, the light intensity distribution is strong at both ends and weak in the center. Become. Then, the reflected light from the document surface is projected onto the image sensor 7 through the lens 6. Due to the convergence effect of the lens 6, the light intensity distribution is almost uniform as shown in Fig. 3. Become. Therefore, the intensity distribution of the light projected onto the image sensor 7 via the lens 6 is non-uniform. By bending the flexible substrate 10 in a direction that eliminates the Even if a lens 6 with relatively strong power is used, a uniform light intensity distribution can be obtained on the image sensor 7. That will happen.

[0009] Moreover, as a result, the lens 6 has a strong power, that is, a relatively short focal length. As shown in FIG. 4, the distance D between the original 3 and the image sensor 7 is shortened. The entire device can be easily made compact, and the optical path can be bent to make it more compact. This eliminates the need for mirrors and the like, resulting in lower manufacturing costs.

0010

[Effect of the idea]

As explained above, according to the light source of the image reading device according to this invention, the document surface When the reflected light is projected onto the image sensor through the lens, the light intensity distribution is uniform. This also makes it possible to use lenses with relatively strong power, that is, short focal lengths, to improve original image quality. An important practical advantage is that the distance between the camera and the image sensor can be shortened, and manufacturing costs can be reduced. have.

[Brief explanation of drawings]

FIG. 1 is a side view of an embodiment of a light source of an image reading device according to the present invention.

FIG. 2 is a diagram showing a light intensity distribution of irradiation light on a document surface according to the above embodiment.

FIG. 3 is a diagram showing a light intensity distribution when reflected light of the irradiation light on the document surface is projected onto an image sensor through a lens according to the above embodiment.

FIG. 4 is a schematic diagram of an image reading device including the above embodiment.

FIG. 5 is a schematic diagram of a conventional image reading device.

FIG. 6 is a side view of a conventional example.

FIG. 7 is a diagram showing a light intensity distribution of irradiation light on a document surface according to a conventional example.

FIG. 8 is a diagram showing the light intensity distribution when the reflected light of the irradiation light on the document surface is projected onto the image sensor through the lens according to the conventional example.

[Explanation of symbols]

3 Manuscript 6 Lens 7 Image sensor 9 Light emitting element 10 Flexible board 11 Sheet metal 15 Light source

Claims (1)

[Scope of utility model registration request] Claim 1: An image reading device in which reflected light of light irradiated on a document surface is projected onto an image sensor through a lens, comprising: a flexible substrate having a plurality of light emitting elements arranged at equal intervals on its surface; , a sheet metal bonded to the back surface of the flexible substrate to hold the flexible substrate in a curved state.