JP2685191B2 - Image information reader - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical system used in a reflective original reading unit such as a facsimile and an image reading apparatus. 2. Description of the Related Art Facsimile machines and other devices are provided with an image reading device for reading the information of an original document. As a conventional example of such an image reading device, for example, Japanese Patent Laid-Open No. 61-129961 or No. 3 is used. Some are shown in the figure. This image reading apparatus includes a light source 2 that illuminates an original 1 sent to a reading position, a mirror 3 that regulates an optical path of light diffusely reflected from the original in a certain direction, and a light reflected by the mirror 3. A lens 4 for forming an image and a photoelectric conversion element 5 for converting an image formed by the lens 4 into an electric signal are incorporated. In reading the original, the light from the light source 2 is reflected on the surface of the original 1, and the reflected light is imaged on the photoelectric conversion element 5 by the lens 4 to read the original. DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in such a conventional image reading apparatus, since the light source 2 is disposed relatively close to and exposed in the housing of the document reading unit, When the light emitted from the light source 1 is diffusely reflected on the surface of the document 1, a part of the reflected light is generated on the surface of a light emitting member such as a fluorescent tube constituting the light source 1,
In some cases, it may hit the member around the document reading section and be reflected again, and may reach the surface of the document 1 twice. As a result, the amount of light on the surface of the document 1 becomes non-uniform, which appears as uneven output after photoelectric conversion. The present invention has been made in view of the above problems, and an object of the present invention is to provide an image reading apparatus capable of reducing unevenness in the amount of light in a document reading unit and performing highly accurate document reading. Means for Solving the Problems In order to achieve the above object, the gist of the present invention is to provide a reflected light regulating member between a document illumination light source of an image reading apparatus and a document. The light emitted from the light source passes through the reflected light restricting member, reaches the surface of the original document, and is irregularly reflected, and a part of the irregularly reflected light is reflected by the mirror and enters the lens and the photoelectric conversion element. Further, a part of the diffused reflected light from the surface of the original goes toward the light source, but since the reflected light regulating member is arranged between the light source and the original, the diffused reflected light is blocked and a fluorescent tube or the like is provided. You cannot reach the light source of. Therefore, the illumination light does not reach the surface of the document twice, and the document reading unit can read the document with a uniform light amount. Embodiment FIG. 1 and FIG. 2 are views showing an embodiment of an image reading apparatus according to the present invention. The image reading apparatus according to this embodiment includes a light source 12 that illuminates a document 11 sent to a reading position P.
And a mirror for reflecting a part of the light diffusely reflected by the original 11 and changing its optical path to a predetermined angle (90 degrees in this embodiment).
A lens 14 for forming an image of the light reflected by 13, a photoelectric conversion element or linear image sensor 15 arranged at an image forming point of the lens 14 for converting an image formed by the lens 14 into an electric signal, and a light source 12. It is provided with a reflected light restricting member, that is, a beam splitter 16, which is arranged between the original 11 and the original 11. The light source 12 comprises a fluorescent tube 17 extending in the longitudinal direction and a cover member 18 having a slit-shaped window and covering the outer periphery of the fluorescent tube 17, and the window of the cover member 18 is opened to the original reading position P. Are arranged to form a linear light source facing the reading position P. The beam splitter 16 is formed by molding glass or other light-transmissive material into a plate shape, and reflects light on the surface 16a on the side of the document 11 when the glass splitter 16 is installed between the light source 12 and the document 11. While being coated, the surface 16b on the light source 12 side is an uncoated surface. In the image reading apparatus having such a configuration, when the fluorescent tube 17 is turned on when reading a document, the light L1 emitted from the fluorescent tube 17 does not pass through the beam splitter 16 as shown in FIG. From coating surface 16b side to coating surface 16a
Almost all the light is transmitted to the side and reaches the 11th surface of the original. The light L1 irradiated on the original 11 is diffusely reflected, and a part of the light L2 is reflected light L2 toward the light source 12, but the reflected light L2 hits the coating surface 16 of the beam splitter 16 and a half amount (numerically When you see
About 60%) is reflected in the direction A in FIG. As a result, the re-illumination of the original 11 due to the irregularly reflected light does not occur, and the irregularly reflected light L3 having a uniform brightness is always obtained from the original 11.
Then, this light L3 is reflected by the mirror 13 and the lens
The light enters the image sensor 14 and is imaged on the linear image sensor 15 by the lens 14. In the linear image sensor 15, photoelectric conversion is performed on the formed image to create image information. EFFECTS OF THE INVENTION As described above, according to the present invention, in the reading unit of the image reading apparatus, since the regulating member that blocks the diffusely reflected light from the original is provided between the light source and the original, unnecessary reflection from the original surface is prevented. It is possible to eliminate light and keep the illumination light amount on the document surface uniform. As a result, it is possible to obtain an effect such as highly accurate document reading.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic side view showing an embodiment of an image information reading apparatus according to the present invention, FIG. 2 is a view showing a main part of the embodiment shown in FIG. 1, and FIG. It is a figure which shows the conventional image information reader. 11 …… Original, 12 …… Light source, 13 …… Mirror, 14 …… Lens, 15 …… Linear image sensor (photoelectric conversion element), 16
...... Beam splitter (reflected light control member), 17 ...... Fluorescent tube, 18 …… Cover.

Claims (1)

(57) [Claims] A light source that emits light onto the surface of the original, a lens that forms an image of the light reflected from the original, a photoelectric conversion element that is arranged at the image forming point of the lens and that converts the formed image into an electric signal, and the reading of the original. Reflected light regulation, which is arranged on a line connecting a point and the light source, transmits light traveling from the light source to the reading point, and directs diffused reflected light traveling from the reading point of the document toward the light source in a direction opposite to the document. An image information reading device including a member.