JPS63136765A - Color picture forming device - Google Patents

Abstract

PURPOSE:To obtain a color picture with high quality by using plural dichroic mirrors so as to make a direct light and a reflected light from the dichroic mirrors irradiate an original symmetrically. CONSTITUTION:A dichroic mirror 8 reflecting a red color only is arranged adjacent to a green color fluorescent light 3 and similarly a dichroic mirror 9 reflecting a green color only and a dichroic mirror 10 reflecting a blue color only are arranged adjacent to a red fluorescent light 2. The light 3a from the green fluorescent light 3 transmits through the dichroic mirror 8 and radiates directly the original face 5 and a reflected light 3b reflected by the dichroic mirror 10 radiates the original face 5 in two directions. The light 4a from the blue fluorescent light 4 radiates directly the original face 5 and transmits through the dichroic mirror 10 and the reflected light reflected in the dichroic mirror 9 radiates the original face 5 in two directions.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a color image forming apparatus, and particularly to a color copying machine, a color facsimile, etc., which are equipped with an original illumination device consisting of a plurality of light sources and configured to read color images. The present invention relates to a color image forming apparatus that can be suitably implemented.

In recent years, color image forming apparatuses such as color copying machines and color facsimiles have been developed and commercialized. One of the important components of such a color image forming apparatus is a document reading device. The configuration of a document reading device that is currently frequently used is shown in FIGS. 3 and 4.

As shown in FIG. 3, document reading devices generally include:
An original O placed on an original table L made of a transparent glass plate
In order to irradiate the R original surface 5 in a slit shape with a predetermined width,
A plurality of light sources having different spectral characteristics, such as a red fluorescent lamp 2, a green fluorescent lamp 3, and a blue fluorescent lamp 4, are provided below the document table 1. The optical image of the original OR from the original surface 5 is transferred along the optical axis 0 to the image sensor 7 by the imaging lens 6. At this time, the red fluorescent lamp 2, the green fluorescent lamp 3, and the blue fluorescent lamp 4 are arranged close to the document surface 5 in order to improve illumination efficiency, but generally, due to space constraints, this example As such, three fluorescent lamps consisting of a red fluorescent lamp 2, a green fluorescent lamp 3, and a blue fluorescent lamp 4 are arranged asymmetrically on both sides with the optical axis O as the center.

The red fluorescent lamp 2, green fluorescent lamp 3, and blue fluorescent lamp 4, which have different spectral characteristics, sequentially detect the red, green, and blue components on the document surface by shifting their lighting timings and send them as optical images to the image sensor. However, because the light source is arranged asymmetrically with respect to the optical axis, it is necessary to illuminate the document with one of the fluorescent lamps when the document has a binding part that cannot be brought into close contact with the document table, such as a book. In this case, a shadowed area is likely to be created where the light emitted from the fluorescent lamp does not hit, and it may not be possible to illuminate the document with a good color balance for all three colors.

In order to solve this problem, six red fluorescent lamps 2, green fluorescent lamps 3, and six blue fluorescent lamps 4 are arranged symmetrically in pairs around the optical axis O, as shown in FIG. It was proposed to do so. However, since the six fluorescent lamps are arranged in a narrow space, the distance between each fluorescent lamp and the slit-shaped reading portion of the document becomes long, and the irradiation efficiency deteriorates. In particular, when a contact type image sensor is used as the image sensor 7, it is difficult to arrange it in the manner shown in Figure 4 because the exposure system consisting of a fluorescent lamp and the imaging lens are located close to each other. be.

l1211 An object of the present invention is to efficiently arrange a plurality of light sources with different spectral characteristics in a narrow space, to efficiently guide light from the plurality of light sources to the document surface, and to improve the binding area of the document. It is an object of the present invention to provide a color image forming apparatus capable of providing high-quality color images.

. The above object is achieved by a color image forming apparatus according to the present invention. To summarize, the present invention provides a color image forming apparatus in which a document is illuminated in a slit shape with a plurality of light sources having different spectral distributions, and a plurality of light sources having different spectral distributions arranged adjacent to the illuminated surface of the document. It is equipped with multiple light sources and multiple dichroic mirrors that reflect light from one light source and transmit light from other light sources. This is a color image forming apparatus characterized in that reflected light from the image forming apparatus is irradiated from symmetrical directions.

Next, the color image forming apparatus according to the present invention will be explained in more detail with reference to the drawings.

FIG. 1 shows an embodiment of a color image reading device when a color image forming apparatus according to the present invention is applied to an electrophotographic color copying device. Other image forming sections, such as the electrophotographic photoreceptor on which latent images are formed, charging section, developing section, transfer section, cleaning section, fixing section, etc., are well known to those skilled in the art, so detailed explanations will be omitted. .

In this embodiment, the irradiated surface of the original OR placed on the original table L made of a transparent glass plate, that is, the document surface 5, is placed below the document table 1 in order to irradiate it in the form of a slit with a predetermined width. A plurality of light sources having different spectral characteristics, such as a red fluorescent lamp 2, a green fluorescent lamp 3, and a blue fluorescent lamp 4, are arranged. Original side 5
The optical image of the original OR is transferred along the optical axis 0 to the image sensor 7 by the imaging lens 6. The image signal from the image sensor 7 is processed and exposed to a photoreceptor.

The red fluorescent lamp 2, green fluorescent lamp 3, and blue fluorescent lamp 4 are arranged close to the document surface 5 in order to improve illumination efficiency, but in this embodiment, the red fluorescent lamp 2, Three fluorescent lamps, each consisting of a green fluorescent lamp 3 and a blue fluorescent lamp 4, are arranged asymmetrically on both sides of the optical axis 0.

According to the present invention, a dichroic mirror 8 that reflects only red light is further arranged adjacent to the green fluorescent lamp 3, and a dichroic mirror 9 that reflects only green light is similarly arranged adjacent to the red fluorescent lamp 2. A dichroic mirror 10 that reflects only blue light is provided.

To explain further, the light 2a emitted from the red fluorescent lamp 2 passes through the dichroic mirror 9.10 and directly illuminates the document surface 5, and the reflected light 2b reflected by the dichroic mirror 8 illuminates the document from the opposite direction. Irradiate surface 5. Light 3a from the green fluorescent lamp 3 passes through the dichroic mirror 8 and directly illuminates the document surface 5, and the reflected light 3b reflected by the dichroic mirror 10 illuminates the document surface 5 from two directions. Light 4a from the blue fluorescent lamp 4 directly irradiates the original surface 5, and also passes through the dichroic mirror 10 and is reflected by the dichroic mirror 9. The reflected light irradiates the original surface 5 from two directions.

As described above, according to the present invention, although the space required for the light source that illuminates the document surface 5 is approximately the same size as the conventional device shown in FIG. Irradiation efficiency can be increased.

Furthermore, according to the present invention, since the illumination light from each fluorescent lamp 2.3.4 is irradiated onto the document surface 5 from both sides around the optical axis, it is possible to illuminate the document surface 5 from both sides with the optical axis as the center. Good illumination can also be achieved, eliminating shadows and producing images that are faithful to the original.

FIG. 2 shows another embodiment of the invention. According to this embodiment, the dichroic mirrors 8.9.10 in FIG. 3 are configured not in a flat shape but in a curved shape to improve the irradiation efficiency.

In the above embodiments, the light source is a fluorescent lamp, but the light source is not limited to a fluorescent lamp, and various other light sources such as a light emitting diode array light source, a cold cathode tube light source, etc. can be used. Furthermore, it is clear that a light source equipped with an ordinary reflective shade or the like can also be used.

Further, the present invention is not limited to a method of reading a document by sequentially blinking a plurality of light sources, but, for example, a light source having a specific spectral distribution that is a combination of several different types of light sources may be used as one light source. This can also be applied to other cases.

As explained above, according to the image forming apparatus according to the present invention, the irradiation efficiency is dramatically improved, and since the document can be illuminated from two directions, it is possible to illuminate the binding part of the document, etc. This has the advantage that shadows that tend to occur can be removed, high-quality images can be obtained, and the space required for document illumination can be small.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an embodiment of a color reading device portion of a color image forming apparatus according to the present invention. FIG. 2 is a sectional view of an embodiment of a color reading device portion of a color image forming apparatus according to the present invention. FIG. 3 is a sectional view of an example of a color reading device portion of a conventional color image forming apparatus. FIG. 4 is a sectional view of another example of a color reading device portion of a conventional color image forming apparatus. 1: Original table transparent glass 2: Red fluorescent lamp 3: Green fluorescent lamp 4: Blue fluorescent lamp 5: Original surface 8.9.1o: Dichroic mirror Figure 1 Figure 3 Figure 4 Figure 2 Approval

Claims (1)

[Claims] 1) A color image forming apparatus in which a document is illuminated in a slit shape with a plurality of light sources having different spectral distributions,
A plurality of light sources with different spectral distributions are arranged adjacent to the irradiated surface of the original, and a plurality of dichroic mirrors that reflect light from one light source and transmit light from other light sources, A color image forming apparatus characterized in that the illuminated surface of a document is irradiated with direct light from each light source and reflected light from a dichroic mirror from symmetrical directions. 2) The device according to claim 1, wherein the dichroic mirror is formed in a flat or curved shape.