JPS60134556A - Color original reader - Google Patents

Abstract

PURPOSE:To attain miniaturization of a reader by arranging a color separation device to an object side of an image forming lens so as to use a lens short in back focus. CONSTITUTION:A reflected light from an original 0 is made incident on a reflecting element 3, a red light component is reflected by a dichroic mirror 3A and the light of the other colors is reflected on a totally reflection mirror 3B. Then the light reflected by the mirrors 3A, 3B is made incident on a reflecting element 4, the blue light component is reflected by a dichroic mirror 4A, the light of the other colors is reflected on a totally reflection mirror 4B and the light reflected on the element 4 is reflected further on a flat mirror 5. Then the light reflected on the flat mirror 5 is fed respectively to solid-state image sensors 9, 10, 11 via image forming lenses 6, 7, 8, where the light is converted into an electric signal. Thus, the color original 0 is read as an electric signal.

Description

[Detailed description of the invention] (Technical field) The present invention relates to a color document reading device.

(Prior Art) Various types of color document reading devices are known in the past that separate color documents into three primary colors and read them.

Conventionally known color document reading devices generally use a single imaging lens to form an image of the color document reading section, and divide the optical path of the imaging light beam into three parts on the image side of the imaging lens. Then, each of the three divided imaging light beams is guided to the corresponding solid-state image sensor, and an image is formed on the light receiving area of the sensor, and each of the three divided imaging light beams is subjected to color separation. . Such conventional color document reading devices have the following problems.

That is, the light reception growth of the circumferential image sensor is smaller than the reading width of the document. Therefore, the image formed by the imaging lens has a reduced magnification. Therefore, the optical path length between the imaging lens and the solid-state image sensor is shorter than the optical path length on the object side of the imaging lens. However, on the image side of the imaging lens,
Since it is necessary to provide an optical system for splitting the optical path and a color separation means, it is necessary to use a lens with a long tl bank focus for the imaging lens, and as a result, the optical path length becomes large and the device becomes large. .

Furthermore, because images are formed on a plurality of solid-state image sensors using one imaging lens, focus adjustment is extremely troublesome.

(Objective) Therefore, an object of the present invention is to provide a novel color document reading device that effectively solves the above-mentioned problems.

(composition) The present invention will be explained below.

The color document reading device of the present invention is a device that separates and reads a color document into three primary colors α, β, and γ. It has a lens and color separation means.

The illumination scanning means illuminates and scans a document, that is, a color document to be read.

One of the three solid-state image sensors photoelectrically converts an image separated into alpha colors. Another one photoelectrically converts the image separated into β colors, and one of the saws is
The image separated into γ colors is photoelectrically converted.

The three imaging lenses include three solid-state image sensors,
The image of the color document reading unit is formed on the light receiving area of the corresponding solid-state image sensor.

The color separation means separates the light from the color original into three primary colors α.

Color separation into β and γ. This color separation means is arranged on the object side of the three imaging lenses.

Illumination scanning of the original may be performed by moving the illumination optical system with respect to a fixed color original, or conversely, by moving the color original with respect to the illumination optical system, or
It is also possible to move both the illumination optical system and the color original and perform illumination scanning using the relative displacement of the two.

As the solid-state image sensor, a so-called CCD, BBD, etc. can be used.

The color separation means has two types of reflective elements. These two types of reflective elements are formed by forming a dichroic mirror on the front surface of a transparent plate and a total reflection mirror on the back surface.

Furthermore, the two types of reflective elements described above have a thickness sufficient to separate the color-separated light beams from each other.

Hereinafter, description will be given based on specific examples.

In the embodiment shown in FIG. 1, 0 is a color original, 1 is a document mounting glass, 2 is an illumination lamp, 3 and 4 are reflective elements, 5 is a plane mirror, and 6, 7, and 8 are connectors. Image lenses, reference numerals 9, 10 and 11 indicate solid-state image sensors, respectively.

A color document 0 having color information to be read is placed flatly on a document placement glass 1 with the surface having the edge information facing downward.

In this example, it is assumed that the three primary colors α, β, and γ are red, green, and blue, respectively.

Now, when the illumination lamp 2 is turned on in the state shown in FIG. It is illuminated through the glass 1 in the form of a slit whose longitudinal direction is orthogonal to the drawing.

The reflected light from the original O first enters the reflective element 3.

This reflective element 3 is formed by forming a dichroic mirror 3A on the front surface of a transparent plate such as glass, and a total reflection mirror 3B on the back surface. The dichroic mirror 3A has an optical property of reflecting red light components and transmitting light of other colors. Therefore, of the light incident on the reflective element 3, the red light component is reflected by the microink mirror 3A, and the light of other colors is reflected by the total reflection mirror 3B.

The light reflected by the dichroic mirror 3A and the total reflection mirror 3B of the reflective element 3 is then reflected by the reflective element 4.
incident on .

The reflective element 4 is formed by forming a dichroic mirror 4A on the front surface of a transparent plate such as glass, and a total reflection mirror 4B on the back surface. Dichroic ink mirror 4A reflects blue light,
It has the optical property of transmitting light of other colors.

Reflection elements 3, 4 and - are two types of reflection elements. These reflective elements 3 and 4 are referred to as two types of reflective elements because the dichroic ink mirrors formed in each reflective element have different optical properties.

Now, of the light incident on the reflective element 4, the blue light component is
The light of other colors is reflected by the total reflection mirror 4A, and the light of other colors is reflected by the total reflection mirror 4B.

The light reflected by the reflective element 4 is then reflected by the plane mirror 5.

Here, considering the red light component of the light reflected from the color original O, this red light component is first reflected by the dichroic mirror 3A of the reflective element 3. The light component is separated into a green light component, is reflected by the total reflection mirror 4B of the reflection element 4, is reflected by the plane mirror 5, and then enters the imaging lens 7, which converts the color original 4 ( A reduced image of the illuminated area of :ho is formed. A solid-state image sensor 1o is placed at the image plane of this reduced image.

On the other hand, the blue light component and the green light component separated from the red light component by the reflective element 3 are separated from each other by the dichroic mirror 4AiC of the reflective element 4.

That is, the blue light component is reflected by the dichroic mirror 4A and then enters the imaging lens 8 via the plane mirror 5. The solid-state image sensor 11 has an imaging lens 8
The light-receiving area is aligned with the imaging plane of the

Further, the green light component transmitted through the dichroic ink mirror 4A is reflected by the total reflection mirror 4B, and then enters the imaging lens 6 via the plane mirror 5. solid state image sensor
9 is arranged so that its light receiving area coincides with the imaging surface of the imaging lens 6.

The solid-state image sensors 9', 10, and 1.1 have the same structure, and are integrated by arranging seven rays of minute light-receiving elements in one row at minute intervals in one direction, giving them a self-scanning function. It becomes. In these solid-state image sensors, the light-receiving area is the area beyond the array of microscopic light-receiving elements.

Further, the direction in which the light receiving elements are arranged is referred to as the longitudinal direction of the light receiving area.

Since the light-receiving element is extremely small, the light-receiving area is linear, and as shown in FIG.
The light receiving area No. 11 has its longitudinal direction perpendicular to the drawing.

As mentioned above, the solid-state image sensors 9, 10, 11 are
Color originals are placed on the imaging lenses 6, 7, and 8, respectively.
As is clear from FIG. 1, the solid-state image sensors 9, 10,
Each of the light-receiving areas 11 corresponds to a portion of the color original O indicated by the symbol P.

This portion P is a linear region whose longitudinal direction is perpendicular to the drawing. As can be easily understood from the explanation in this section, the reduced image of this linear region P is for each solid-state image sensor ~9.1.0. The image is focused on 11 light receiving areas. Therefore, the linear area pf is called a reading section.

Now, as mentioned earlier, the imaging lenses 6, 7.8 have
Since the green light component, red light component, and blue light component of the reflected light from the non-original original O are respectively incident, the reduced images formed in the light receiving areas of the solid-state image sensors 9 and 10° 11 are as follows. This is a color-separated image of green, red, and blue of color document 0 in reading section P. Therefore, by driving each solid-state image sensor 9°10.11, it is possible to convert the color separation images described in 2 into electrical signals, and scan the color original 0 to the right in Fig. 1. At the same time, by repeatedly driving the solid-state image sensors 9, 10, and 11, the color original 0 can be separated into three primary colors and read.

As mentioned above, there are various methods for scanning the color original O, but in this embodiment, scanning is performed by moving an optical system. That is, the illumination lamp 2 and the reflection element 3 are integrated and sent to the right in Figure 1 at a speed of ■, and at the same time, the reflection element 4 and the plane mirror 5 are integrated and sent 1/2 to the right. Send at a speed of 2v. In this case, the illumination lamp 2, the reflective elements 3 and 4, the plane mirror 5, and the mechanism (not shown) for moving these constitute the illumination scanning means.

Instead of moving the optical system, move the color original O to the left in FIG. Good too. In this case, the document conveying means and illumination lamp 2 (not shown) constitute illumination scanning means.

Regardless of the illumination scanning method for the original O, the color separation means in the example shown in FIG.
4. Consists of a plane mirror 5.

In FIG. 1, reflected light from a color original O is color-separated by reflective elements 3 and 4 as color separation means and a plane mirror 5, and separated into red, blue, and green color component light beams. The color component light beams separated from each other in this way must be shifted and incident on the imaging lenses 6, 7.8 so as not to overlap each other.

For this purpose, it is necessary to separate the color separation beams from each other by at least the pupil of the imaging lens 6, 7.8. This separation of color-separated luminous fluxes is performed in the following way:
This is done by utilizing the thickness of the reflective elements 3 and 4.

That is, in the example shown in FIG. 1, the thickness of the reflective element 3 is used to shift the red component luminous flux and the luminous flux of other colors by the above-mentioned pupil, and the thickness of the reflective element 4 is utilized to shift the red component luminous flux and the luminous flux of other colors. , the blue component light flux and the green component light flux are separated from each other by twice the pupil.

FIG. 2 shows another embodiment of the invention. To avoid confusion, please refer to the first page for items that are considered to have no risk of confusion.
The same symbol as in the figure is 4=j.

To explain the newly appeared symbols in FIG. 2, the symbol 4
0 indicates a reflective element, and numeral 41 indicates a plane mirror. Dichroic mirror 4O formed on the surface of the reflective element 40
A has the same optical properties as the dichroic mirror 4A of the reflective element 4 shown in FIG.

Therefore, in this example, the green component light flux, the blue component light flux, and the red component light flux enter the imaging lenses 6 and 7.8, respectively. In this example, the red light component is transferred to the plane mirror 41.
Since the reflective element 40 is used exclusively to separate the blue light component and the green light component, the reflective element 40 can be smaller and thinner than the reflective element 4 (FIG. 1).

FIG. 3 shows yet another embodiment of the invention.

In this example as well, if there is no risk of confusion,
The same symbols as in FIG. 1 are used.

To explain the newly appeared symbols in FIG. 3, the symbol 30
indicates a plane mirror, and numerals 31 and 41 indicate a reflective element. The dichroic mirror 31A of the reflective element 31 reflects red light and transmits light of other colors.

Furthermore, the dichroic mirror 41A of the reflective element 41 is T
Reflects r color light and transmits light of other colors.

In this example, solid-state image sensors 9, 10, 11 are
Each color separation image of blue, green, and red is converted into an electrical signal. In the example shown in FIG. 3, the color separation is performed by a reflective element;
Since this is done after 31, the height of the mounting section 16' in the vertical direction in FIG. 3 can be reduced accordingly.

Note that in both the embodiments shown in FIGS. 2 and 3, the color original 4'
The scanning of i":5o is also possible with the IJX document movement method and the chair 7L with the optical system movement method.

(Effects) Hereinafter, according to the present invention, a novel color document reading device can be provided. In this color document reading device, the color separation means is provided on the object side of the imaging lens, so there is no need to use an imaging lens with a long back focus. Therefore, the reading device can be downsized. In particular, as an imaging lens, one with a short back focus, which has been conventionally used for reading black and white originals, can be used as is.

Still, since focusing is performed separately for each imaging lens, it is extremely easy to perform focusing.

[Brief explanation of the drawing]

FIG. 1 is a front view schematically showing only the essential parts of one embodiment of the present invention, FIG. 2 is a front view schematically showing only the essential parts of another embodiment of the present invention, and FIG. 3 is a front view schematically showing only the essential parts of an embodiment of the present invention. FIG. 7 is a front view schematically showing only the main parts of still another embodiment. 0...Color original, 1.Original placement glass, 2...Illumination lamp, 3.4.31.40.41 Reflective element, 3A,
40A, 31A, 41A-dichroic mirror, 3B, 4B... total reflection mirror, 6.7.8 imaging lens, 9.10. 11. Solid-state image sensor.

Claims (1)

[Claims] An apparatus for reading a color original by separating it into three primary colors α, β, and γ, comprising: an illumination scanning means for illuminating and scanning the original; three solid-state image sensors; Three imaging lenses are installed corresponding to each image sensor, and focus the reduced image of the reading section onto the light receiving area of each corresponding solid-state image sensor, and the three primary colors of light from the color document are used. a color separation means for separating colors into α, β, and γ; and the color separation means is provided on the object side of the three imaging lenses, and the two types of reflective elements have a thickness sufficient to separate the color separation light beams from each other;
A color document reading device featuring: