JP2003046718A - Image reader and imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reader by which color images can be read at a high speed, even if LEDs of several colors simultaneously emit light, and the electrical power can be saved. SOLUTION: The image reader is provided with a LED array 1, having several LEDs exhibiting different emission wavelengths, an imaging optical system 6 for imaging the reflection from a document and a photoreceptor 7 for receiving image information. The photoreceptor 7 has the function of color separation for spatially separating the imaging light by wavelength distribution. When a document is illuminated by all the LEDs of the LED array 1 which simultaneously emit light, the imaging light of different colors is color-separated simultaneously.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus and an image forming apparatus such as a digital copying machine and an MFP.

[0002]

2. Description of the Related Art A color image reading apparatus using an LED as a light source is well known, for example, Japanese Patent Laid-Open No. 10-136159. The color image reading apparatus shown in the publication uses a light source having an LED for emitting light for each color of red, green and blue. When reading an image, each color is sequentially turned on and the image information for each color is read. Because of this, 1
This means that one document is read three times.

[0003]

The LED has advantages such as power saving and long life, and is a device which is currently drawing attention in various industrial fields. An image reading device using an LED as a light source has been conventionally proposed as described above. However, in the conventional image reading apparatus using the LED as the light source, the color separation is performed by sequentially lighting the LEDs of each color, which increases the number of times of reading the image information.
There is a problem that reading takes time.

The present invention has been made in view of the above problems, and it is possible to read a color image at a high speed even when the LEDs for a plurality of color lights are simultaneously emitted, and a power saving image reading apparatus and image are provided. An object is to provide a forming device.

[0005]

In order to achieve the above object, the invention according to claim 1 provides a plurality of LEs having different emission wavelengths.
In an image reading apparatus including a light source including an LED array having D, an image forming optical system that forms an image of reflected light from a document, and a light receiving unit that receives the image information of the formed image, the light receiving unit is , Which has a color separation function that spatially separates the imaged light for each wavelength distribution, and simultaneously illuminates the original by simultaneously emitting all the LEDs in the LED array, image reading that simultaneously separates the tie light of each color The device is the most important feature.

According to a second aspect of the present invention, a light source including an LED array having a plurality of LEDs having different emission wavelengths, an image forming optical system for forming an image of reflected light from a document, and receiving image information of the formed image. In the image reading apparatus including a light receiving unit for performing the above, a color separation unit, which is independent of the light receiving unit and spatially separates image-forming light for each wavelength distribution, is provided in an optical path on the upstream side of the light receiving unit. The most important feature is an image reading device that simultaneously separates the tie light of each color when the originals are illuminated by simultaneously emitting all the LEDs in the array.

The invention according to claim 3 is characterized mainly in the image reading device according to claim 1 or 2, wherein the light source uses LEDs of at least three colors.

According to a fourth aspect of the present invention, the light source has a plurality of Ls each having a different emission wavelength for at least one color.
The image reading apparatus according to claim 3 using an ED is a main feature.

The fifth aspect of the present invention is most characterized by an image forming apparatus equipped with the image reading apparatus according to the first or second aspect.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of an image reading apparatus according to a first embodiment of the present invention. As the light source, the LED array 1 in which LEDs of three colors of red, green and blue are linearly arranged in the direction perpendicular to the paper surface is used. The color original 2 is illuminated by the LED array 1. The reflected light of the color original 2 enters the image forming optical system 6 through the reflecting mirrors 3, 4, 5 and is imaged by the light receiving section 7.

FIG. 2 is an array diagram of the LED array in the first embodiment. R, G and B in the figure are red, green and blue LEDs, respectively. Returning to FIG. 1 again, the light receiving unit 4 uses a three-line sensor. Each line of the line sensor has on-chip color filters having different transmission wavelength regions.

Next, the operation will be described. Color original 2
When reading, all the LEDs on the LED array 1 are made to emit light at the same time, and the color original 2 is illuminated. FIG. 3 shows the light emission distribution of the irradiation light from the LED array. R, G, and B in the figure show the emission wavelength distributions from the red, green, and blue LEDs, respectively. The output of the light emission intensity of each LED is adjusted so that the signal intensity of each color is substantially equal. Each color light emitted simultaneously from the LED array 1 is reflected on the original surface. The reflected light is guided to the imaging optical system 6 via the reflection mirrors 3, 4, 5, and then, in the light receiving section 7, color separation is performed by an on-chip color filter, and photoelectric conversion is performed for each color component. After that, the signals of the respective color components are combined into color image information.

In this way, in this embodiment, even when LEDs having a plurality of wavelength distributions simultaneously emit light,
The image information for each color component can be read.
Therefore, the reading time can be shortened. Also,
Since the LED array 1 is used as the light source, the emission intensity for each color can be adjusted more easily than the conventionally used light source such as a xenon lamp or a cold cathode tube.

Here, another feature of the present embodiment will be described. FIG. 4 shows the relationship between the emission wavelength distribution of the LED and the transmission wavelength of the color filter. R, G, in the figure
B shows the emission wavelength distributions from the red, green, and blue LEDs, respectively, and r, g, and b show the transmission wavelength regions of the color filters used in the red, green, and blue light receiving portions, respectively.

Since the wavelength distribution of the LED array 1 is discrete, there are many areas where no light is emitted. Within that area, the quality of the color filters varies, and as shown by b and g in the figure, the transmissive areas are shown. Even if they overlap with each other, or conversely, if the transmissive regions are separated from each other like g and r, there is no difference in reading the image information. That is, the use of the LED array 1 having a discrete wavelength distribution has a feature that the degree of freedom in designing the color separation means (color filter) is increased.

FIG. 5 is a block diagram of an image reading apparatus according to the second embodiment of the present invention. Further, FIG. 6 is an array diagram of the LED array in the second embodiment. As the light source, the LED array 1 in which LEDs of three colors of red, green, and blue are linearly arranged in the direction perpendicular to the paper surface is used. The color original 2 is illuminated by the LED array 1. The reflected light of the color original 2 enters the image forming optical system 6 through the reflecting mirrors 3, 4, 5 and is imaged by the light receiving section 7.

In the first embodiment, the light receiving section 7 has a color filter, but in the second embodiment, the color separation means is provided independently of the light receiving section 7 in the optical path on the front side thereof. 8 are provided.

The color separation means 8 provided in the optical path is for performing spatial color separation of the reflected light for each wavelength.
The color separation means 8 may be a dichroic mirror or a diffraction grating. The light receiving unit 7 has three line sensors,
They are arranged at intervals in the sub-scanning direction.

Next, the operation will be described. Color original 2
When reading, all the LEDs on the LED array 1 are made to emit light at the same time, and the color original 2 is illuminated. FIG. 7 shows a light emission distribution of irradiation light from the LED array. R in the figure
LE is red, G1 and G2 are both green, and B is blue.
The emission wavelength distribution from D is shown. Both G1 and G2 are light emitted from green LEDs having different emission wavelengths, and G is a sum spectrum of G1 and G2. Each color light emitted simultaneously from the LED array 1 is reflected on the original surface. The reflected light is guided to the image forming optical system 6 through the reflecting mirrors 3, 4 and 5, and then is separated into three components of red, green and blue used for color reading by the color separation means 8 and then in the sub-scanning direction. Spatial color separation. Then, photoelectric conversion is performed by the light receiving unit 7 for each color component. After that, the signals of the respective color components are combined into color image information.

In this way, in this embodiment, even when LEDs having a plurality of wavelength distributions simultaneously emit light,
The image information for each color component can be read.
Therefore, the reading time can be shortened.

Two green LEDs having different emission wavelengths
By using, the irradiation light is distributed in a relatively wide band in the green region. Therefore, the color reproducibility of image information for green can be improved. In the present embodiment, LEDs having different emission wavelengths are used only for green, but of course, LEDs having different emission wavelengths for red and blue are also used.
Can be used.

FIG. 8 is a block diagram of the image forming apparatus according to the embodiment of the present invention. The image forming apparatus is equipped with the above-described image reading apparatus of the present invention. In this example, the image reading apparatus of the first embodiment shown in FIG. 1 is installed.

The image information read by the image reading device is transferred to the optical writing optical device 11, the LD in the optical writing optical device 11 repeats ON / OFF based on the image signal, and the LD on the photosensitive drum 12 is transferred. The light spot scans. The photoconductor drum 12 is charged by a charger 13, and an electrostatic latent image is formed by optically scanning the charged photoconductor drum 12, and the electrostatic latent image is developed by a developing device 14 as a toner image. Is developed as. Paper is guided from the paper feed tray 15 to the photoconductor drum 12 by the paper feed roller 16,
The transfer roller 17 transfers the toner image onto the paper. The toner image on the paper is fixed by the fixing device 18, and the paper is ejected to the paper ejection tray 20 by the paper ejection roller 19. The photoconductor drum 12 is destaticized and cleaned by the destaticizing cleaner 21, and the process from charging is repeated again.

[0024]

According to the first or second aspect of the present invention, there is provided an image reading apparatus which can read a color image at a high speed and save power even if LEDs for a plurality of color lights are simultaneously emitted. Can be provided.

According to the third aspect of the invention, the image reading apparatus according to the first and second aspects can enable full-color image reading.

According to the invention described in claim 4, in the image reading apparatus described in claims 1 and 2, color reproducibility can be improved.

According to the invention described in claim 5, it is possible to provide an image forming apparatus capable of reading a color image at a high speed and saving power even if LEDs of a plurality of color lights are simultaneously emitted.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an image reading apparatus according to a first embodiment of the present invention.

FIG. 2 is an array diagram of an LED array according to the first embodiment.

FIG. 3 is a diagram showing a light emission intensity spectrum distribution of the LED array in the first embodiment.

FIG. 4 is a diagram showing a light emission intensity spectrum distribution of the LED array and a transmission characteristic of a color filter of a light receiving unit in the first embodiment.

FIG. 5 is a configuration diagram of an image reading apparatus according to a second embodiment of the present invention.

FIG. 6 is an array diagram of an LED array according to a second embodiment.

FIG. 7 is a diagram showing a light emission intensity spectrum distribution of the LED array according to the second embodiment.

FIG. 8 is a configuration diagram of an image forming apparatus according to an embodiment of the present invention.

[Explanation of symbols]

1 LED array (light source) 2 color manuscript 6 Imaging optical system 7 Light receiving part

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H04N 1/04 101 H04N 1/04 DF term (reference) 2H108 AA01 CA01 CB01 2H109 AA13 AA26 5B047 AA01 AB04 BB02 BC01 BC05 BC07 BC11 BC14 CA19 5C051 AA01 BA03 DA03 DB01 DB22 DB23 DB29 DB31 DC04 DC07 EA01 FA01 5C072 AA01 BA03 CA05 CA07 CA12 DA02 DA09 EA04 FA07 QA10 XA01

Claims (5)

[Claims] 1. A light source comprising an LED array having a plurality of LEDs having different emission wavelengths, an image forming optical system for forming an image of reflected light from a document, and a light receiving section for receiving the formed image information. In the image reading apparatus including the above, the light receiving unit has a color separation function of spatially separating the image-forming light for each wavelength distribution, and when all the LEDs in the LED array are simultaneously illuminated to illuminate the original document, An image reading apparatus that simultaneously separates the tying light of the image. 2. A light source comprising an LED array having a plurality of LEDs having different emission wavelengths, an image forming optical system for forming an image of reflected light from a document, and a light receiving section for receiving the formed image information. In the image reading apparatus including the above, a color separation unit, which is independent of the light receiving unit and spatially decomposes image-forming light for each wavelength distribution, is provided in the optical path on the upstream side of the light receiving unit, and all the LEDs in the LED array are provided. An image reading apparatus that simultaneously separates the synthesizing light of each color when illuminating a document by simultaneously emitting light. 3. The image reading apparatus according to claim 1, wherein the light source uses LEDs of at least three colors. 4. The image reading apparatus according to claim 3, wherein the light source uses a plurality of LEDs each having a different emission wavelength for at least one color. 5. An image forming apparatus comprising the image reading device according to claim 1 or 2.