JP2827273B2 - Image reading device - Google Patents

Description

The present invention relates to the field of information processing and office equipment, and more particularly to an image reading device and a copying machine.

2. Description of the Related Art An image reading device is used as a means for inputting image information to an information processing device. In general, the optical information of a document from which image information is to be obtained is converted into electromagnetic information by a photoelectric conversion unit, that is, an image sensor, so that the information processing device can process the image information.

As a typical image reading device, there is an image reading device that illuminates a document using a fluorescent tube, a halogen lamp, an LED, or the like as a light source, forms a reduced real image of the document on an image sensor using a lens, and reads the image. Was. The optical system of such an image reading apparatus is called a reduction optical system.

[Problems and Object to be Solved by the Invention] FIG. 3 is a sectional view showing the arrangement of optical system elements in an image reading apparatus using a conventional reduction optical system. Light emitted from the light source 1 is reflected on the surface of the document 2 and is reflected on the surfaces of the first reflecting mirror 3, the second reflecting mirror 4, and the third reflecting mirror 5, and then reaches the line image sensor 7 through the lens 6. The image of the document 2 is reduced and formed on the light receiving pixels of the line image sensor 7. Image reading includes main scanning and sub-scanning. In FIG. 3, the main scanning direction is perpendicular to the paper surface. The light receiving pixel rows of the line image sensor 7 are arranged in the main scanning direction, and the main scanning is performed by the electrical operation of the line image sensor 7. The sub-scan is performed in the vertical direction with respect to the main scan, and is performed by relatively moving the original 2 and the reading optical system.

The optical imaging performance of the lens 6 is anisotropic,
There is a direction in which the resolution becomes highest in the image plane.
Since the main scanning line is one of the rays centered on the optical axis on the image plane, the direction with the highest resolution can be represented by one point on the circumference when the lens 6 is regarded as a cylinder,
A mark indicating the direction of the highest resolution (hereinafter, referred to as a use direction) is written on the end surface of the lens barrel by means of paint or the like on most of the lenses used in the image reading apparatus. When the reading optical system as shown in FIG. 3 is assembled and adjusted, it is necessary to confirm that the use direction of the lens 6 is at an appropriate position. However, the lens 6 is a structural member (not shown) of the reading optical system. It is difficult to directly see the mark indicating the direction of use of the end surface of the lens barrel in the state of being incorporated in the parentheses. SUMMARY OF THE INVENTION An object of the present invention is to provide an image reading apparatus capable of easily confirming a position in a use direction of a lens during assembly adjustment.

[Means for Solving the Problems] In order to solve the problems described above, in the present invention, the position of the reflecting mirror of the image reading apparatus is specified, and the position of the lens in the use direction can be confirmed.

[Operation] The position of the lens in the use direction can be confirmed by visually observing the virtual image on the end surface of the lens barrel using the back reflection of the reflecting mirror.

[Example] A detailed description of the present invention will be given according to an example.

FIG. 1 is a sectional view of a reading optical system of an image reading apparatus according to an embodiment of the present invention. The light traveling order and the basic components are the same as those in FIG. In this embodiment, the second reflecting mirror 4 is disposed immediately before the lens 6. FIG. 2 is an enlarged sectional view of the vicinity of the second reflecting mirror 4 and the lens 6 of FIG. A use direction indicating mark 8 is marked on the end surface of the lens barrel 6a of the lens 6. The reflecting mirror 4 has a reflecting surface 4a formed by evaporating aluminum on the surface. Although this reflecting mirror is used as a front reflecting mirror, the back surface of the reflecting surface also has a reflecting ability. Therefore, a virtual image 8 'of the use direction indicating mark 8 is formed at the position shown in the drawing due to the reflection of the back surface of the reflection surface 4a, and the virtual image 8' can be visually observed within the range of the angle α in the drawing. Thus, the lens 6
The user can easily check the direction of use. If there is no use direction in the normal range, the adjustment can be easily made by adjusting while looking at the virtual image 8 '. If a mark indicating the range in which the use direction indicating mark 8 of the lens 6 is to be formed is formed on the structural member holding the optical system element, it is easier to confirm and adjust.

[Effects of the Invention] As described above, according to the present invention, the maximum resolution direction of the lens can be easily confirmed by adding specific conditions to the arrangement of the reflecting mirror, and the process of assembling and adjusting the image reading apparatus can be greatly improved. Can be reduced. In addition, since only a condition is added to the arrangement of the reflector, no special parts are required, and the arrangement can be realized without increasing the cost by considering the arrangement of the reflector from the design stage.

[Brief description of the drawings]

FIG. 1 is an arrangement sectional view of an optical system element of an image reading apparatus according to an embodiment of the present invention. FIG. 2 is a partially enlarged view of FIG.
FIG. 3 is a sectional view showing the arrangement of optical system elements in a conventional image reading apparatus. DESCRIPTION OF SYMBOLS 1 ... Light source 2 ... Original document 3 ... First reflecting mirror 4 ... Second reflecting mirror 4a ... Reflecting surface 5 ... Third reflecting mirror 6 ... Lens 6a ... Barrel 7 ... Line image sensor 8 …… Use direction indication mark 8 ′ …… Virtual image

Claims (1)

(57) [Claims] An image reading apparatus for forming a reduced real image of a document on a solid-state imaging device using a reflecting surface of a reflecting mirror and a lens to read an image, wherein a back surface of one of the reflecting surfaces is provided. An image reading apparatus which is configured to be capable of reflecting light, and wherein the back surface of the reflecting surface is located in an optical path connecting an end face of the lens barrel and an external viewing portion for confirming the position of the end face.