JPH02180465A - Color picture reader - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a color image reading device such as a color facsimile or a color scanner that separates and reads the color information of a document.

[Prior Art and Problems to be Solved by the Invention] Conventionally used color image fs reading devices include those shown in FIGS. 5 to 8.

The apparatus shown in Fig. 5 consists of red (R), green (G), Ft (
B) has lights 1111a, lb, and lc that emit light of each wavelength, and slit illumination is performed by switching the original 3 placed on the cover glass 2 for each color. The reflected light having information for each color reflected by the original 3 is passed through the f-elephant lens 4.
The light is focused onto the light receiving element 5 in a line shape.

The light-receiving element 5 is a one-dimensional sensor such as a COD line sensor, and detects information contained in the document for each predetermined line.

The original [3] is scanned relative to the optical system, and information on the entire original is read.

There is a method of switching the lighting three times for each line,
There is a method of repeating scanning for one page for each color.

However, when using the former method, it is necessary to take into account the afterglow of the fluorescent tube used as a light source and secure switching time, and when using the latter method, it is necessary to ensure that the scanning of the document is
Each page must be flipped three times, which takes three times as long as black and white. Therefore, in either case, the time required for reading increases.

The device shown in Figure 6 emits white light that almost covers the visible range! I! The original 3 is illuminated by Jl, and the original and the imaging lens 4 are illuminated.
The reflected light is color-separated by a wavelength-selective filter 6 provided between the light-receiving element and a line image of the document is formed on the light-receiving element. Filters 6 are provided for each color of RGB, and are supported by a disc-shaped holder 68. There is a method of changing the filter for each line or for each page, similar to the above-mentioned changing of the light source.

However, even when this device is used, the former method requires a sufficient amount of time for the filter to stabilize, while the latter method has the same problems as described above.

On the other hand, the apparatus shown in FIG. 7 illuminates the document 3 using a white light source, and separates the reflected light into each color by a color separation prism 7 provided on the output side of the imaging lens. Each light is received by an independent light receiving element 5.

With such a configuration, the above-mentioned problem of reduced reading speed can be solved.

However, it is necessary to arrange the three light receiving elements 5 at optically equivalent positions, and high positioning accuracy between the elements is required. In addition, since the pitch between pixels of the light-receiving element itself varies depending on the individual product, the image of the same point on the document may be formed on pixels at different addresses depending on the element, and when reproducing the read/jr1 information, There is a risk of color misalignment.

In FIG. 8, in order to eliminate each of the above-mentioned problems, a configuration is adopted so that reading can be completed in one scan using one light receiving element 5. That is, the light receiving element 5 has an RGB filter for each Iil'1g arranged on the line, and 3
Color information of a document can be read pixel by pixel.

However, in such a configuration, the amount of information to be read is 173 for each of the above-mentioned images, and the image quality when reproduced is degraded.

[Objective] The present invention has been made in view of the above-mentioned problems, and aims to provide a color rB1 image reading device that reduces the time required for reading and does not reduce image quality.

[Means for Solving the Problem] A color image reading device according to claim ii includes a light source, an imaging lens that focuses reflected light from a JJR manuscript illuminated by the light source, and a plurality of one-dimensional sensors on an l chip. It is characterized by having a light-receiving element in which pixel elements (1) are formed in parallel, and a color separation means for color-separating the reflected light and separating and condensing each color of luminous flux onto the pixel rows on the light-receiving element. Claim 2 is characterized in that the luminous flux of the light source includes almost the entire visible wavelength range and illuminates the document with slits. Claim 3 is characterized in that the -dimensional pixel rows are three rows, and the light is received after being separated into three primary colors. A fourth aspect of the present invention is characterized in that the pixel array of the light receiving element is two-dimensional, and three of the pixel arrays are used for reading.

[Example] The present invention will be described below based on the drawings. 1 and 2 show an embodiment of a color image reading device according to the present invention.

This device includes a white light source 10 whose luminous flux includes almost the entire visible wavelength range, and a cover glass 21 on which a document 20 is placed.
and an imaging lens 30 that focuses reflected light from the original 20.
, two two-layer dichroic mirrors 40.50 as color separation means for separating the reflected light into three primary color information, and a light receiving element 60 that receives the reflected light and outputs the information of the document as an electric fi number. The first dichroic mirror 40 has a dichroic mirror for reflecting the B component on the outermost surface 41 on the side where the light beam enters, and a coating for reflecting the G component on the bonded surface 42 of the two layers. The R component transmitted through each surface is the back surface 4.
It is configured so that it is reflected at 3.

Further, the second dichroic mirror 50 has an outermost surface 51
The bonding surface 52 is coated to reflect the R component, and the bonding surface 52 is coated to reflect the G component, so that the transmitted B component is reflected by the back surface 53.

As shown in FIG. 2, the light receiving element 60 includes three one-dimensional pixel rows 61. ．． 62.63, and is arranged so that each of the three primary color components color-separated by the dichroic mirror 40.50 is focused on each pixel column. ■By forming pixel rows in parallel on the chip, it is possible to prevent pixel pitch deviation.

When the light beam is deflected by 45 degrees as in this example, the thickness of each layer of the dichroic mirror is set so that the first layer and the second layer are equal, thereby increasing the optical path length followed by the light beam of each color component. can be made equal. Further, the thickness of each layer of the dichroic mirror may be set in consideration of the vertical color difference on the light receiving element 60 so as to cancel this difference.

Next, the operation of the above-mentioned color image reading device will be explained.

The light beam emitted from the light source 0 illuminates a part of the document by the action of a slit (not shown).

The reflected light from the illuminated source [20] is focused by the imaging lens 30, and is focused by the first dichroic mirror 40.
It is deflected downward in the figure. At this time, the B component is the outermost surface 41
．． The G component is reflected by the bonding surface 42, and the R component is reflected by the back surface 43.

The deflected light beam is deflected toward the light receiving element 60 by the second dichroic mirror 50. At this time, the R component is the outermost surface 51, the G component is the bonding surface 52, and the B component is the back surface 5.
It is reflected at 3.

The color-separated light beams are respectively focused on separate pixel rows 61, 62, and 63 on the light receiving element 60, and an image of the document is formed on these pixel rows.

Each pixel column of the light-receiving element 60 transmits information for one line of the document. It is output as an image signal corresponding to each OB component.

Here, the original 20 is scanned relative to the optical system in a direction orthogonal to the reading line, and information on the original 20 is continuously read.

Note that the color separation means does not necessarily need to be provided closer to the light receiving element 60 than the imaging lens 30 as in the above example;
As shown in the figure, it may be provided closer to the document 20 than the imaging lens 30. Since this optical system is a reduction system, very high positional accuracy is not required when inserting a member closer to the original than the lens, but the overall configuration becomes larger.

When the color separation means is provided closer to the document than the imaging lens 30, the optical axis of each color is shifted before it enters the imaging lens 30, so in principle the action of the imaging lens is different for each color. It happens. However, since the direction of the deviation is in the scanning direction of the document and the amount thereof is small compared to the width of the reading line, the deviation does not occur so large as to affect the operation of the lens as well.

Further, in each of the above examples, two sets of dichroic mirrors are used as color separation means, but color separation may be performed using fractions of prisms.

FIG. 4 shows an example of a pond of light receiving elements.

This light-receiving element 70 is an area sensor having two-dimensional pixel rows, and three rows 71, 72, and 73 shown with diagonal lines in the figure among these II pixel rows are used for reading.

The output of the pixel row in the pond is used as a dummy and is not used for reading.

[Effects] As explained above, according to the present invention, MTS can be read in one scan using one light source, compared to conventional devices that perform reading by switching filters and light sources. can increase reading speed.

Furthermore, since a light receiving element with multiple pixel arrays formed on one chip is used, it is necessary to consider the mutual positional relationship between the elements compared to the conventional configuration in which color-separated light beams are received by multiple independent light receiving elements. This also makes it possible to suppress pitch deviations between pixel columns. Therefore, positioning of the light-receiving element becomes easy, and color shift in the reproduced image can also be prevented.

Furthermore, the amount of information to be read can be increased compared to the conventional apparatus which detects the three primary colors using a plurality of pixel rows, thereby preventing deterioration in reproduced image quality.

[Brief explanation of the drawing]

1 to 4 show an embodiment of a color image reading device according to the present invention, in which FIG. 1 is an explanatory diagram of the entire optical system, and FIG. 2 is a perspective view of a light receiving element. FIG. 3 is an explanatory diagram showing a modification of the optical system, and FIG. 4 is an explanatory diagram showing a modification of the light receiving element. 5 to 8 are explanatory diagrams of an optical system showing a conventional color image reading device. 10... Light source 20... Original [30... Imaging lens 4050... Dichroic mirror (color separation means)
60.70...Photo-receiving element Figure 2 procedural amendment (issued) Patent application title (052) filed on December 29, 1988 4, 1-13-125 Kakigara-cho, Nihonbashi, Chuo-ku, Tokyo , Target of correction FIG. 7 FIG. 8 (1) In the 20th line of page 9 of the specification, the phrase ``affects reading'' is corrected to ``impacts reading performance.'' (2) On page 10, line 3 to line 4 of page 10 of the specification, the phrase "dispersion of a prism" is corrected to "refraction of light by a prism."that's all

Claims (4)

[Claims] (1) A light source, an imaging lens that collects reflected light from a document illuminated by the light source, a light receiving element in which a plurality of one-dimensional pixel arrays are formed in parallel on one chip, and a light receiving element that collects the reflected light. 1. A color image reading device comprising: color separation means for color-separating light beams of each color to separate and focus them on pixel rows on the light receiving element. (2) The color image reading device according to claim 1, wherein the light source emits a luminous flux that includes almost the entire visible wavelength range and illuminates the document with a slit. (3) The color image reading device according to claim 1, wherein the light receiving element has three one-dimensional pixel arrays, and the color separation means separates the reflected light into three primary colors. (4) The color image reading device according to claim 1, wherein the light receiving element has a two-dimensional pixel array, and a plurality of the pixel arrays are used for reading.