JPS5875963A - Picture reader - Google Patents

Abstract

PURPOSE:To obtain an inexpensive and compact picture reader which eliminates unevenness of illumination, by using a Dach-mirror lens array and zigzag arranged solid-state scanning elements in combination. CONSTITUTION:Reflected light from an original 23 lighted by illumination light sources 24 and 25 is passed through the 1st mirror 26 for optical path splitting and a lens array 27, reflected by a Dach-mirror array 28, and passed through the lens array 27 again to strike the 2nd split mirrors 29 and 30. The 2nd mirrors 28 and 30 are divided equally and alternate divisions are grouped in one; and reflected light from the group 29 is guided to a solid scanning element 31, and that from the group 30 is guided to a soild-state scanning element 32 to perform photoelectric conversion. In this case, the 2nd mirrors 29 and 30 are narrower than photodetection parts of the solid-state scanning elements 31 and 32, so adjacent end parts of photodetection parts of the solid-state scanning element overlap each other, thus eliminating unevenness of illumination.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Background of the Invention The present invention relates to an image reading apparatus that reads an original by focusing an image of the original onto a solid-state scanning element.

For example, on the sending side of a facsimile, a document image is usually optically read, converted into an electrical signal, and sent to the receiving side. Photoelectric conversion of the image is performed by a solid-state scanning device such as a 3D image sensor or an amorphous semiconductor image sensor, and the original image is focused on such a solid-state scanning device. Since it has both a charge transfer function and a charge transfer function, an image of one line of the original is converted into a time-series electric signal and extracted.

Solid-state scanning elements cannot be manufactured in long lengths due to manufacturing technology problems. To avoid this problem, conventionally, the original image is reduced and focused on a plurality of solid-state scanning elements, thereby making the solid-state scanning elements substantially longer. However, since this method uses a reduction optical system, it is necessary to use high-performance microlenses, and the magnification error of each lens must be reduced to almost zero, resulting in high cost and adjustment. The disadvantage is that it is difficult and the equipment is large. On the other hand, there is also a method in which short solid-state scanning element packages are arranged in a line with the same length as the width of the original, and an image of the same size of the original is formed on this solid-state scanning element array. Although this method makes the apparatus compact and does not cause magnification errors, it has the disadvantage that no image is formed at the joints of the solid-state scanning element packages, that is, at the portions where the light-receiving portions do not exist. For this reason, the solid-state scanning element pancages are arranged in a staggered manner so that their light-receiving areas are substantially continuous, and one line of the document is divided into two to form an image on the elements in each row. is being carried out.

Along with consideration for such short solid-state scanning elements,
In order to make the apparatus more compact, efforts are being made to create a compact 1-magnification optical system. One known compact equal-magnification optical system uses a converging rod lens.

A focusing rod lens has a refractive index that changes quadratically from its center toward the outside in the radial direction, and has a short object distance, but has the drawback of high cost because it is produced as a single item. Another optical system is one in which three similar plate lenses each having a large number of microlenses arranged in a row are stacked at regular intervals. Although this method has a low cost because the plate lens can be manufactured by integral molding of resin, it has the disadvantage that the object image distance becomes long because it is necessary to form an intermediate image on the center plate lens. On the other hand, in a configuration in which a roof mirror array having a micromirror surface corresponding to each microlens is arranged behind a plate lens, both the plate lens and the roof mirror array can be integrally molded from resin. Moreover, since the light is used back and forth by the mirror, there is an advantage that the object-image distance can be shortened. However, there are some points in which it is not possible to effectively correct illuminance unevenness due to the amount of light at the periphery of each lens.

(2) Summary of the Invention The image reading device according to the present invention includes solid-state scanning element pancages arranged alternately in a staggered manner, and a life-size image of one line of a document divided into two parts on each row of solid-state scanning elements. and an optical system including a lens array and a roof mirror array for forming an image. This optical system also has
The first and second mirrors extend in the same direction as the array and are used to divide the object-side optical path and the image-side optical path, and the second mirror is divided into a plurality of different groups along the long direction. It is divided and arranged so that the angles of the reflecting surfaces in each group are different from each other. Each solid-state scanning element package is arranged in a staggered manner so as to correspond to each reflective surface of each group of the divided second mirror, and the light-receiving area of each solid-state scanning element package is smaller than the width of each reflective surface. is set so that the width of In this case, the light receiving parts of the solid-state scanning element packages that are alternately adjacent to each other overlap each other at their ends, and by electrically adding the output power of this overlapping part, the illuminance unevenness in the roof mirror lens array can be reduced. This is to compensate for this. As described above, since the image reading device according to the present invention uses a roof mirror lens array as the imaging optical system, it is possible to realize an inexpensive and compact device. By a good combination with a second mirror divided correspondingly, it is possible to realize a device with no uneven illuminance.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an improved image reading device using a combination of a roof mirror lens array and solid-state scanning elements arranged in a staggered manner.

A further object of the present invention is to provide the above-mentioned device which is inexpensive, compact and free from uneven illuminance.

Other objects and features of the invention will become apparent from the following description of an embodiment with reference to the drawings.

(3) Description of Embodiments FIG. 1 shows the basic configuration of a roof mirror lens array optical system used in an image reading apparatus according to the present invention. FIG. 2 is a front view of the top view of FIG. 1.

The lens array 1 is made up of a plurality of identical lens elements arranged in a row, and behind it, a roof mirror array 2 having a roof mirror surface corresponding to each lens element is arranged with the centers of both aligned. . Both the lens array 1 and the roof mirror array 2 are integrally molded from resin, and a reflective film of aluminum or the like is formed on each roof mirror surface by vapor deposition or the like. Image formation by such a roof mirror lens array is such that in the array direction shown in FIG. 1, the object 5 is formed as an erect real image 4, and in the direction perpendicular to the array shown in FIG. 2, the object 5 is formed as an inverted real image. The image is formed as a real image 6. Therefore, the images are continuous in the array direction, and can be used as a long imaging optical system.

However, as it is, the object plane and the image plane are located on the same plane and cannot be used, so in reality, as shown in FIG. 6, a roof mirror array 2 is arranged behind the lens array 1, and For example, a right-angle mirror 7 is disposed in front of the lens array 1 to divide the object side optical path and the image side optical path, and the entire lens array 1 is held by a housing 8. The right-angle mirror 7 is composed of a first mirror 9 and a second mirror 10 that face each other and are inclined at 45 degrees with respect to the lens optical axis. Place the original on the object plane 11, and place the original on the image plane 1.
If a photoreceptor is placed on the object surface 11 and the optical device is moved relative to the two, the exposure optical system of the electrophotographic device can be used to place a moving document on the object surface 11 and move the photoreceptor on the image surface 12. If the solid-state scanning element is left still, it becomes an optical system for a reading device such as a facsimile machine. Such an optical device is described in detail in Japanese Patent Application No. 112491/1983 filed by the same applicant as the present application.

FIG. 4 schematically shows an example of a reading device according to the invention. A contact glass 22 is disposed on the upper surface of the apparatus main body 21, and a document 26 is intermittently and continuously conveyed across the casing in the direction of the arrow by a document conveying device (not shown) over the contact glass 22. Below the contact glass 22,
Illumination light sources 24 and 25 are arranged to illuminate the document 23 on the contact glass 22 in a slit shape. As the illumination light sources 24 and 25, in addition to a light emitting diode array, a long fluorescent lamp, a halogen lamp, etc. are used. The reflected light from the illuminated original 23 is reflected by the first mirror 26 for optical path splitting, passes through the lens array 27, is reflected by the da mirror array 28, and passes through the lens array 27 again. The divided second
The light is reflected by mirrors 29 and 50 and enters solid-state scanning elements 31 and 32, which are arranged in a staggered manner, respectively.

As shown in FIG. 5, the second mirrors 29 and 30 are equally divided into a plurality of groups and are grouped every other group, and the angles of their reflecting surfaces are different between one group 29 and the other group 50. . Solid-state scanning elements 31 that receive reflected light from group 29 and solid-state scanning elements 32 that receive reflected light from group 30 are arranged in a staggered manner. Furthermore, a characteristic feature of this invention is that the width l of each second mirror 29 and 60 is also different from that of each solid state scanning element 31.
and 62, the width of the light receiving section is larger. In other words, each second mirror 29.30 is divided into a width l smaller than the width of the light receiving portion of the solid-state scanning elements 31 and 32 used, and each solid-state scanning element 31.32 is divided into
The solid-state scanning elements are arranged in a staggered manner so that the ends of the light-receiving parts of adjacent solid-state scanning elements overlap each other.

The reason for taking such measures is as follows. 6th
As shown in the figure, due to the aperture of each lens element of the lens array 27, the imaging range and the degree of overlapping of images on the image plane by each lens element and the roof mirror are indicated by reference numeral 36. When this optical system is used for line scanning, it is usually located at a location with the least unevenness in illuminance based on the aperture and arrangement pitch of each lens element, such as 34 or 35.
A location as shown in is selected as the line to be used, and the position of the second mirror is also determined according to the position of the selected line to be used. Although the illuminance unevenness on the usage line selected in this way cannot be completely eliminated, it is enough to cause no practical problem when this optical system is used as a reading device for a facsimile, an intelligent copier, or the like.

However, when the second mirror is divided and used as in the present invention, new illuminance unevenness occurs due to the division. That is, each second mirror 29. is divided into a width e. The maximum imaging range on the image plane covered by the filter 0 is el, which is larger than e, and the illuminance distribution is approximately flat in the center, as shown by reference numeral 36, and at both ends in line with the aperture of the lens. It has a trapezoidal shape, with the part decreasing to zero. Therefore, each solid state scanning element 31.
32 so that each fang 2 mirror 29. If the width l of the filter 0 is determined, the illuminance distribution will have valleys at the boundaries, resulting in large illuminance unevenness. Therefore, in the present invention, each second mirror 29. ! Of the imaging range e1 covered by 10, only the range 12 at both ends where the illuminance is reduced and overlaps each other is
By adding in the second hall, a substantially uniform illuminance distribution as shown by reference numeral 37 is obtained, thereby making it possible to realize a reading device with no uneven illuminance.

As described above, in this invention, since a roof mirror lens array is used as an imaging optical system, an inexpensive and compact image reading device can be realized. By cleverly combining the second mirror with the divided second mirror, it is possible to realize a device with no uneven illuminance.

[Brief Description of the Drawings] Figure 1 is a plan view showing the basic configuration of the roof mirror lens array optical system used in the image reading device according to the present invention, and Figure 2 is the optical system shown in Figure 1. The front view and bottom view are a sectional view showing an example of an imaging device using the optical system shown in FIG. 1, FIG. 4 is a schematic view showing an example of an image reading device according to the present invention, and FIG. 6 is a diagram showing the relationship between the divided fang 2 mirrors and the corresponding solid-state scanning elements arranged in a staggered manner in the device shown in FIG. 4, and FIG. FIG. 7 is a diagram showing the relationship between the illuminance distribution, the divided second mirrors, and the light receiving sections of the solid-state scanning elements arranged in a staggered manner. 22... Contact glass, 23... Original, 24.
25... Illumination light source, 26... First mirror, 27...
・Lens array, 28...Dach mirror array, 29.3
0...Second mirror, 31. Filter 2...Solid state scanning element number 4 Drawing 6 Opening, back

Claims (1)

[Claims] A lens array in which a plurality of lenses are arranged linearly, a roof mirror array arranged behind the lens array and having a Dono mirror surface corresponding to each of the plurality of lenses, and a roof mirror array arranged in front of the lens array. an optical path splitting mirror consisting of a first and second degree mirror extending in the same direction as the lens array; and the second mirror is divided into a plurality of different groups along its long extending direction, and each An image reading device comprising: solid-state scanning elements arranged such that the angles of the reflecting surfaces in the groups are different from each other, and solid-state scanning elements arranged in a staggered manner corresponding to the reflecting surfaces in each group, The width of the light-receiving portion of each of the solid-state scanning elements is longer than the width of each reflective surface of the divided second mirror, so that the light-receiving portion of each of the solid-state scanning elements that alternately adjoins the An image reading device that includes an overlapping portion and a device that electrically adds signals of the overlapping portion.