JPS6256070A - Original reader - Google Patents

Abstract

PURPOSE:To miniaturize a light source and to obtain a clear image by reflecting and condensing light from the light source at each area of an original corresponding to an optical image image-formed on each photoelectric transducer group. CONSTITUTION:Luminous flux emitted from a light source 5, after it is reflected directly or by the first reflecting shade 6 and becomes a parallel ray, is made incident on the second reflecting shades 71, 72.... These second reflecting shades 71, 72... reflect and condense the light on each of parts. A and B on the original corresponding to the optical image image-formed on each of the photoelectric transducer groups 21, 22.... The optical image of each of the parts A and B on the original is image-formed on each of the photoelectric transducer groups 21, 22... by an image-forming lens 3, being converted to an electrical signal. Afterwards, the whole surface of the original is read out by the movement in the direction of an original reader C. Thereby, the read outpart of the original can be irradiated efficiently and the light source can be miniaturized, and also, since the light is not irradiated so much on the part other than the read out one, little flare light is generated, obtaining the clear image.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a document reading device used in copying machines, facsimile machines, and the like.

(Prior Art) Conventionally, there is a document reading device using a photoelectric conversion element such as a CCD as shown in FIG. ” Bipedal CC
D image sensor array 211.

Since it is difficult to manufacture a long one, as shown in FIG. 6, the CCD image sensor arrays 211, 212...
2... optical TLF conversion element group 221.

222... are arranged so that there is no gap in the longitudinal direction and so that they do not face each other in the east. Manuscript! ! An optical image of the document (not shown) on the table 23 is formed on the CCD image sensor arrays 211, 212, . . . via the lens 24. However, these CCD image sensor arrays 2
The light from the light source 25 is reflected by the reflective shades 26 and 27 to uniformly illuminate the entire area E of the document corresponding to the optical images formed on the optical images 11, 212, . . . . Note that the document reading device configured as shown in 1: scans in the direction C in the figure to read the entire surface of the document.

(Problems to be Solved by the Invention) However, in the case of this prior art, the CCD image sensor array 211 is arranged in two rows.

The entire area E of the document corresponding to the optical image formed at 212 . . . is uniformly illuminated. Therefore, the areas other than those corresponding to the photoelectric conversion element groups 221, 222, . . . of each CCD image sensor array 211, 212, .
1, the light from the light source 25 is dispersed over the entire region @E of the document, and the amount of light irradiated to the regions F, H of the document corresponding to each charge conversion element group 221, 222, . . . is small.

Therefore, there is a problem in that the light source 25 must be enlarged in order to obtain a sufficient amount of light in each photoelectric conversion element n22x, 222, . . . . In particular, in a device that reads documents at high speed, the amount of light received during the opening time at I'n is further reduced, so a light source 25 with a large amount of light emission is required, and the amount of heat generated increases accordingly. There is a problem that stages are required and the device becomes larger. Furthermore, in the case of reading a color image, the image must be formed on a group of photoelectric conversion elements through a filter, so a larger light source is required as the amount of light is reduced by the filter, which increases power consumption. Furthermore, since there is a large amount of illumination light in areas other than those required for reading, flare light tends to enter the imaging lens 24, making it difficult to obtain a clear image.

The present invention was made in order to solve the problems of the prior art described in (1). An object of the present invention is to provide a document reading device that can obtain clear images.

(Means for solving problems) Tree 95. In order to achieve the above object, Kawa has developed photoelectric conversion element groups arranged in multiple rows, optical means for forming an optical image of a document onto these photoelectric conversion element groups, and optical means for focusing an optical image of a document on each of the photoelectric conversion element groups. The document illumination means includes document illumination means that reflects and focuses light from a light source on each area of the document corresponding to the optical image to be imaged.

(Example) The present invention will be explained below based on the illustrated example. 1st
In the figure and FIG. 2, 11, 12... are CCD image sensor arrays, and these CCD image sensors
As shown in FIG.
Each CCD image sensor is arranged in two rows in E.
Optical city conversion element group 21 of arrays 11, 12... 2
2... are arranged so that there is no gap in the longitudinal direction and that they do not overlap each other. Reference numeral 3 denotes an imaging lens for forming an optical image of a document (not shown) placed on the document table 4 onto the photoelectric conversion element groups 21, 22, . . . .

5 is the original on the manuscript table 4! This is a light source for illuminating A (not shown). 6 is a first reflective shade, and as shown in the figure, its cross section is a parabola, and the light source 5 is located at its focal point. Therefore, the light emitted from the light source 5 that is reflected by the reflective shade 6 becomes substantially parallel light. 71, 72, . . . are second reflecting shades, each having a focal point at A, H on the document surface, and directs substantially parallel light reflected by the first reflecting shade 6 to A, H on the document surface -L. It is made up of a part of a paraboloid that almost condenses light into H.

Points A and B on the document surface are located at each of the photoelectric conversion element groups 21.
．． This is the area of the document corresponding to the optical image formed on 22.... To explain in more detail, the second reflective shade 71.72.
... and CCD image sensor array tl, t2...
are arranged in the positional relationship shown in FIG. That is, the second reflective shade 71.

72... is also a CCD image sensor array 11.

12... are arranged alternately in two rows.

Therefore, the light emitted from the light source 5 passes through the first reflective shade 6.
After being reflected by and becoming parallel light, the second reflective shade 71
．． 72..., each CCD image sensor array 11.12... photoelectric conversion element group 21.22...
The light is focused on each area of the document corresponding to the optical image formed on the image.

Note that the light source 5, the first reflective shade 6, and the second reflective shade 71
．． 72..., the imaging lens 3 and the CCD image sensor array 11.1□... are integrally scanned in the direction C in the figure to read the entire surface of the original. In this case, the above-mentioned original reading device The components may be fixed and the original may be moved.

In the above configuration, the document reading device for the unissued month I reads the document as follows. That is, the luminous flux emitted from the light source 5 is reflected directly or by the first reflective shade 6 to become parallel light beams, and then passes through the second reflective shade 7.
1. 72... These second reflective shades 71
．． 72... is a group of elements 21, 22... that convert the respective lights.
1: The light described in 1: is reflected and focused on each portion A and B of the document corresponding to the optical image formed in . Each part of this manuscript A
, B are focused by the imaging lens 3 onto the respective optical 'trL conversion element groups 21, 22, . . . 1-, and converted into electrical signals. Thereafter, by moving the document reading device in the direction C in FIG. 1, the entire surface of the document is read.

” - As shown in the figure, the luminous flux from the light source 5 is reflected by the second reflective shade 71.
．． 72..., each photoelectric conversion element group 21.2.・
Each part A, H of the original corresponding to the optical image formed on...
Since the light is focused on the light source 5, the light flux from the light sources 5 can be used efficiently, and even a small light source can illuminate the document with a sufficient amount of light.

3 and 4 show another embodiment of the document reading device according to the present invention, and the same parts as in the previous embodiment are denoted by the same reference numerals. It is designed to read originals. That is, as shown in FIG. 4, the CCD image sensor array 8 includes a photoelectric conversion element 8-21 having several to several thousand optical conversion elements r- in one row.

22, 23 are provided 3 days a week, and the element group 21 [-
A color reading sensor is constructed by inserting a blue filter 9 into the element group 221, a green filter 10 into the element group 221-, and a red filter 11 into the element group 23. Therefore, the second
Reflective shade 71. 72. 73 has three curved surfaces, and the reflective shade 7E is designed to focus light almost on the part of the document that can be imaged on the photoelectric conversion element group 23 provided with the red filter 11.
The 6 or 2 reflective shades 72, which are composed of paraboloids having a focal point approximately at the portion H of the X draft 4121 unit 4, correspond to the photoelectric conversion element group 22 provided with the green filter 10. In the 1G/1 reflection shade 71, the blue filter 9 is constituted by a paraboloid having a focal point at a position B corresponding to the sunken photoelectric conversion element group 21, respectively. In this example.

A telecentric optical system is used for the imaging lens 3.

The principal rays of the optical image reflected from the R, G, and B positions of the original travel to the optical axis of the lens 3 and the f line, and enter the lens 3, where the aperture is placed at the focal position of the lens 3. 12 and is imaged onto each photoelectric conversion element group 23.22.2x, j-, where it is converted into an electrical signal. The document reading station St configured as described above is moved in the direction of the arrow mark relative to the document placing table 4 to read the document.
Spectral distribution of photoelectric conversion element group 21. Although it varies depending on the spectral sensitivity of 22.23, the characteristics of filters 9.10.11, etc., blue sensitivity is generally poor and red sensitivity is good. In such a case, the amount of light illuminating the original can be changed depending on the color by changing the ratio of the reflective areas of the second reflective shade 71, 72° 73, making the area of the reflective shade 73 larger than the area of the reflective shade 71, etc. It is also possible to make the sensitivity of each color uniform.

In addition, in the illustrated embodiment, the second reflective shade 71.

72...and 71. 72. 73 is formed into a parabolic shape [J1 type, but is not limited to this, a case where a plurality of cylindrical lenses are arranged on the surface of a flat reflective shade as a second reflective shade is also considered. The light converging point may be fixed at each position on the document as described above.

(Effect of emission II) The non-emission 1!1 has the following configuration and operation, and the light '7 that is imaged through the optical L stage on the photoelectric conversion element group arranged in multiple rows. - The light from the light source is reflected and focused on each part of the document that corresponds to the image, so the reading area of the document can be efficiently illuminated, making it possible to downsize the light source and Since not much light is applied to areas other than the reading area, there is less flare light and a clear image can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional front view showing an embodiment of the document reading device according to Unpublished '[1, FIG. 2 is a view taken in the X direction of FIG.
4 is a top view showing the CCD image sensor array of FIG. 3, FIG. 5 is a longitudinal sectional front view showing a conventional document reading device, and FIG. This figure is a top view showing the arrangement of the CCD image sensor array of FIG. 5. Explanation of sign

Claims (1)

[Claims] A group of photoelectric conversion elements arranged in a plurality of rows, an optical means for forming an optical image of a document on these photoelectric conversion element groups, and each portion of the document corresponding to the optical image formed on each of the photoelectric conversion element groups. A document reading device comprising: document illumination means for reflecting and condensing light from a light source.