JP2008193448A - Reading module, image reader, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reading module in which a light source and a CCD being an imaging element are differently configured, and which eliminates the problem to be an expensive device to be made compact and inexpensive. <P>SOLUTION: The reading module reducingly forms an image on the imaging element from reflected light from an illuminated original by an image forming lens system, reads the image one-dimensionally and reads two-dimensional image by scanning the image. A three-line color CCD is arranged at a board 12, the reflected light from the original is made to advance and return a plurality of times by a mirror group 8, an image forming lens 9 makes an image on the CCD 11, and the image is read one-dimensionally. A light emitter 4 using an LED is arranged on a rear board surface opposite from the surface with the CCD 11 on the board 12. The LED belonging to the light emitter 4 and the CCD 11 are arranged so as not to overlap on each other even when projected. Consequently, an image can be read while maintaining operating environment satisfactorily without making emitted heat affect each other so that the improvement of image quality can be achieved. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a document reading module used in a copying machine, a facsimile, a printer, an image scanner, and a multifunction peripheral (MFP) having two or more of these functions, and in particular, a digital such as a digital copying machine or a digital laboratory (?). BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reading module such as a manuscript that can be used in a reading device used in a system apparatus, and an image reading device and an image forming apparatus using the same.

  In recent years, a light emitting diode (hereinafter referred to as an LED) has been actively developed, and the brightness of the LED element has been rapidly increased. LEDs generally have advantages such as long life, high efficiency, high G resistance, and monochromatic light emission, and are expected to be applied in many lighting fields. One of the applications is a document illumination device of an image reading apparatus such as a digital copying machine or an image scanner.

  Conventionally, as a configuration for use in an image reading apparatus, a contact image sensor in which an LED chip as a light source and a sensor IC as a light receiving element are arranged on a substrate is known. However, this type of sensor is effective when the distance from the object to be read to the light receiving element is short. In the reduced CCD reading system (see Patent Document 1, etc.), the light source is placed on the original surface in order to increase the illumination efficiency. It was difficult to arrange them on the same substrate as the CCD.

  Therefore, a method of illuminating from a distance has been proposed even with a reduced CCD reading method (see, for example, Patent Document 2).

  In the barcode reader, there is an example in which a laser diode as a light source and a photodiode as a light receiving element are arranged on a substrate (see, for example, Patent Document 3).

Japanese Patent Laid-Open No. 10-136158 JP 2006-25403 A JP 2003-196581 A JP-A-10-126572

  However, in the conventional techniques described above, there is a problem that both the light source and the CCD as the image sensor are separately configured, resulting in an expensive device.

  Accordingly, the present invention aims to reduce the size and cost of this type of apparatus.

  According to the first aspect of the reading module of the present invention, the reflected light from the illuminated original is reduced and formed on the image sensor by the imaging lens system, and the image is read one-dimensionally and scanned. Accordingly, in the reading module for reading a two-dimensional image, the illumination light source is provided on a substrate on which the imaging element is mounted.

  According to a second aspect of the present invention, in the reading module of the first aspect, a plurality of the light sources are provided.

  According to a third aspect of the present invention, in the reading module according to the second aspect, a condensing function member that condenses a plurality of light beams emitted from the plurality of light sources on the document surface is provided.

  According to a fourth aspect of the present invention, in the reading module according to the second aspect, an optical system is provided that superimposes a plurality of light beams emitted from the plurality of light sources on the document surface.

  According to a fifth aspect of the present invention, in the reading module according to any one of the first to fourth aspects, an LED is used as the light source.

  According to a sixth aspect of the present invention, in the reading module of the fifth aspect, at least one of three colors of red, green, and blue can be emitted using at least three LEDs as the light source. To do.

  According to a seventh aspect of the present invention, in the reading module of the sixth aspect, the number of the red, green, and blue LEDs is set so that the number of reds ≦ the number of blues ≦ the number of greens.

  According to an eighth aspect of the present invention, in the reading module of the sixth or seventh aspect, the power supplied to the red, green, and blue LEDs is set such that power to red ≦ power to blue ≦ power to green A reading module.

  According to a ninth aspect of the present invention, in the reading module according to any one of the first to eighth aspects, the light source is mounted on a substrate surface on the back side of the substrate surface on which the imaging element is mounted.

  According to a tenth aspect of the present invention, there is provided the reading module according to the ninth aspect, wherein the image pickup device and the light source are mounted at a position that does not overlap with a projection position on the substrate surface.

  According to an eleventh aspect of the present invention, in the reading module according to any one of the first to tenth aspects of the present invention, the reading module includes a mirror that reflects the illumination light emitted from the light source and guides the illumination light to the document surface. A reading module which can be adjusted by moving a position.

  According to a twelfth aspect of the present invention, in the reading module according to the eleventh aspect, the illumination position can be adjusted after adjusting the reading optical axis of the image sensor.

  According to a thirteenth aspect of the present invention, in the reading module according to any one of the first to tenth aspects, the illumination light emitted from the light source is parallel light or substantially parallel light, and the read optical axis immediately before entering the image sensor and the reading light A reading module, wherein an optical axis of the illumination light immediately after being emitted from a light source is parallel or substantially parallel.

  According to a fourteenth aspect of the present invention, in the reading module according to any one of the eleventh to thirteenth aspects, the mirror that reflects the illumination light emitted from the light source and guides it to the document surface, and a plurality of light beams emitted from the light sources A sub-module is formed by integrating an optical system for superimposing on the original surface and a condensing function member for condensing a plurality of light beams emitted from the respective light sources on the original surface, and at the time of adjusting the optical axis of the illumination light A reading module characterized in that the sub-module can be moved together.

  According to a fifteenth aspect of the present invention, in the reading module according to any one of the first to fourteenth aspects, the image pickup device is a CCD.

  An image reading apparatus according to a sixteenth aspect includes the reading module according to the first to fifteenth aspects.

  An image forming apparatus according to a seventeenth aspect includes the image reading apparatus according to the sixteenth aspect.

  In the present invention, the reflected light from the illuminated original is reduced and imaged on the image sensor by the imaging lens system, the image is read one-dimensionally, and the two-dimensional image is read by scanning the image. , A light source such as an LED is provided on a substrate on which an image sensor such as a CCD is mounted, so that a small and low-priced reading module can be provided, thereby reducing the size of the image reading apparatus and the image forming apparatus. The price can also be reduced.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a cross-sectional view showing an outline of an image forming apparatus to which a reading module and an image reading apparatus according to the present invention are used. This apparatus can transmit an image read by a communication module (not shown) by facsimile. In the figure, reference numeral 100 denotes an image forming unit, 200 denotes a paper feeding unit, 300 denotes an image reading apparatus of the present invention, and 400 denotes a document feeding unit. The image reading apparatus 300 can read a two-dimensional image by scanning the above-described reading module in a sub-scanning direction by a driving device (not shown).

  Then, the document feeder 400 automatically or manually feeds the document directly above the image reading unit. The image forming unit 100 forms a color image on a plurality of photoconductors based on the color-separated information of the read image, and superimposes and transfers the image on a transfer sheet sent from the paper feeding unit 200. Make a full color hard copy.

  FIG. 2 is a perspective view showing a configuration of an embodiment of the reading module according to the present invention, and FIG. 3 is an enlarged cross-sectional view of a main part. In the illustrated reading module 1, reference numeral 2 denotes a contact glass, which is a transparent glass, which is also called a document table, and a document such as a sheet or a book is placed on the upper surface. In the figure, reference numeral 3 denotes an illumination unit. Although the detailed explanation of the interior is omitted here, the reading area is illuminated through a light emitter 4 using an LED, an adjustment mirror 5, an illumination lens group 6, and a condenser reflector 7 (details). Will be described later).

  Reflected light by irradiating the original on the contact glass 2 with the condensing reflecting mirror 7 passes through a mirror group 8 composed of a plurality of reflecting mirrors and an imaging lens 9, and the one-dimensional CCD (hereinafter simply referred to as CCD) of the reading unit 10. Read at 11). In the figure, reference numeral 12 denotes a substrate.

  The imaging lens 9 is generally configured by integrating a plurality of lenses with a lens barrel, and forms an image of the reading region on the CCD 11. The CCD 11 converts image light in the reading area obtained through the imaging lens 9 into an electric signal. The reading unit 10 is configured by integrating an imaging lens 9 and a CCD 11. In the present specification, the main scanning direction refers to the direction read by the CCD, and the sub-scanning direction refers to the direction perpendicular to the same direction as the direction read by the CCD 11.

  The various elements described above are provided in the traveling body 13 except for the contact glass 2. In other words, the illumination unit 3, the reading unit 10, each lens and mirror are integrated, and parallel to the contact glass 2. The vehicle is driven in the sub-scanning direction (left-right direction in FIG. 3) by a driving device (not shown). The entire reading area X is an area obtained by multiplying the range read by the CCD 11 and the range in which the traveling body 13 moves. In FIG. 2, reference numeral 14 denotes a reading module housing.

  Here, the structure of the illumination unit used for a present Example is demonstrated. FIG. 4A is a top view, which is a developed view of the optical axis as viewed from the contact glass 2 side when mounted on the image reading apparatus, and FIG. 4B is a front view of the front view.

First, a description will be given with reference to FIG. This figure is a diagram for explaining the illumination state in the main scanning direction.
The LED array 15 is a light emitting diode and uses three colors of R (red), G (green), and B (blue). Thereby, an inexpensive lighting device can be provided. Although only four are shown in the figure, it is sufficient that there are at least three of each color, and even an integer multiple thereof may increase only the colors with a small amount of emitted light in consideration of the color balance. In this embodiment, illumination with good color balance is realized using one R (red), two G (green), and one B (blue) (that is, the number of R (red) ≦ B The number of (blue) ≦ the number of G (green) In the case of using the same number of each color, the illumination with good color balance can be obtained by adjusting the input current value as follows, and R (red) ≦ B ( Blue) ≦ G (green).

  The rotary parabolic mirror PR places an LED at a focal position and reflects a light beam emitted from the LED to make parallel light. However, since the light emitting surface of the LED has a certain area, not a point, the luminous flux emitted from other than the focal position diverges from the parallel light and diverges and deviates from the parallel light as the focal point shifts. The main illumination lens CA2 is a cylinder (lens) array that illuminates an irradiation target surface (reading region) by expanding a light beam that has been converted into parallel light by the rotary parabolic mirror PR. The shape is such that cylinders (lenses) are arranged as shown in FIG. The focal length is preferably f2 = 1 / ((1 / a) + (1 / c)). The main condensing lens CA1 is a cylinder (lens) array for efficiently putting parallel light including divergent light into the main illumination lens CA2. The shape is the same as that of the main illumination lens CA2 and the focal length is preferably f1 = c. However, even if the same f2 as that of the main illumination lens CA2 is used, the efficiency is hardly lowered. If the main condenser lens CA1 and the main illumination lens CA2 are the same, the management burden during manufacturing, sales, service, etc. can be reduced.

  The main integrated lens L matches the sub-optical axis of the light beam divided by the main condenser lens CA1 and the main illumination lens CA2 with the center of the illumination target surface, and the light beam illuminated by each cylinder of the main illumination lens CA2 on the illumination target surface. Superimpose. The focal length is F = a. The shape is obtained by cutting an unnecessary portion of a general circular convex lens in the sub-scanning direction. By superimposing, color unevenness can be eliminated, and more efficient illumination can be achieved. Moreover, illumination ripple can be reduced.

  With this configuration, all the light beams that pass through the width m of the cylinder (lens) that is each element of the main condenser lens CA1 and the main illumination lens CA2 that are the cylinder (lens) array are in the reading area of the illumination target surface. Irradiate within the width M. In this case, if the number of LEDs does not match the number of cylinders in the cylinder array, the influence of the profile formed by the LEDs and the rotary parabolic mirror PR is eliminated, and the illumination target surface can be made uniform. However, when the number of cylinders exceeds twice the number of LEDs, it may be an integer multiple.

  Next, a description will be given with reference to FIG. This is a diagram for explaining the illumination state in the sub-scanning direction. The behavior of the top view shown in FIG. 4A is the same until the luminous flux emitted from the LED exits the rotary parabolic mirror PR. However, the main condensing lens CA1 and the main illumination lens CA2 behave in the same way as there are parallel plates when viewed from this surface, and therefore pass through the parallel light without being affected.

  The main integrated lens CL1 uses the main integrated lens L in FIG. 4B as a cylinder. The main scanning direction is a cylinder (lens) having the same curvature as the focal length of the main integrated lens L and the sub-scanning direction being straight. Again, the sub-scanning direction passes through the parallel light without being affected.

  The condensing reflection mirror CL2 has a condensing function in the sub-scanning direction on a concave mirror placed near the illumination target surface. The focal length is f (CL2) = a ′.

  With this configuration, the light beam emitted from the rotary parabolic mirror PR reaches the condensing / reflecting mirror CL2 while remaining as a parallel light beam (including a divergent light beam), and the above-described LED chip image magnification is a. It becomes' / F (PR), and it is suppressed to several times, and efficient illumination can be realized.

  Referring also to FIG. 3, a three-line color CCD is disposed on the substrate 12, and the reflected light from the original is reflected a plurality of times by the mirror group 8, and is imaged on the CCD 11 by the imaging lens 9. The image is read. The light emitting body 4 using LEDs is disposed on the substrate surface on the back side of the substrate 12 on which the CCD 11 is disposed. Further, FIG. 5 shows a layout of the substrate as viewed from the direction of light emission from the LEDs of the light emitter 4. The CCD 11 and the LED are arranged at positions where they do not overlap even when projected. As a result, it is possible to read an image while maintaining a good operating environment without the influence of heat generated from each other, and image quality can be improved. A plurality of illumination units 3 using LEDs (4 units in this embodiment) are arranged in the main scanning direction so that a sufficient amount of illumination light can be secured, thereby obtaining a good image. .

  Illumination light emitted from the LED and reflected by the parabolic mirror PR to become parallel light is emitted in the opposite direction in parallel or substantially parallel to the reading optical axis. Then, it is folded back by the adjusting mirror 5, passes through the illumination lens group, and is condensed and reflected by the condenser mirror to illuminate the original surface. Efficient illumination can be achieved by condensing light.

  FIG. 6 shows a method for adjusting the illumination position. The illumination position can be changed by moving the adjustment mirror 5 as shown in FIG. As a result, the illumination optical axis can be adjusted independently of the reading optical axis, and the adjustment time can be shortened and simplified. Further, efficient reading can be performed by aligning a portion with a high illumination light amount with the reading optical axis. Further, since the illumination optical axis is adjusted after adjusting the reading optical axis, readjustment of the optical axis is unnecessary, and the adjustment time can be shortened. Note that if the reading optical axis is adjusted after the illumination optical axis is determined, the illumination optical axis may not necessarily coincide with the adjustment of the tip skew, and there is a problem that the readjustment of the illumination optical axis is necessary.

  Furthermore, since the illumination light reflected from the LED to the rotary parabolic mirror PR and converted into parallel light is parallel to the reading optical axis, the adjustment mirror 5 can be adjusted and moved in that direction to simplify the mechanism. Therefore, the adjustment time can be shortened and simplified.

  Further, the adjustment mirror 5, the illumination lens group 6, and the condensing / reflecting mirror 7 can be formed as a sub-module by a side plate or bracket (not shown) so that the illumination optical axis can be adjusted without changing the illumination distribution in the main scanning direction. Can do.

  That is, in this embodiment, the optical information reader of Patent Document 3, the contact type image sensor, the image read / write head, and the image read / write apparatus of Patent Document 4 cannot be used in a reduction optical system (CCD reading method). The distance problem is solved by using an optical system that superimposes light from a long-distance light source on the document surface.

  Further, as described in the light source for document illumination of the color image reading apparatus of Patent Document 1, “the LED light source is arranged near the document and a dedicated substrate for the light source is raised, resulting in an expensive device”, patent The substrate on which the CCD 11 is mounted in the image reading apparatus and the image forming apparatus disclosed in Document 2 "the light source is arranged at a location far away from the original, but the dedicated substrate for the light source is raised to become an expensive apparatus" This is solved by disposing the light-emitting body 4 as a light source on the (SBU) 12 and eliminating the dedicated light source substrate.

  Furthermore, since a plurality of illumination light sources are provided to ensure a sufficient amount of light and a clear image can be obtained, the MTF (Modulation Transfer Function) can be further improved.

  Of course, an image reading apparatus provided with the above-described reading module can obtain a high-quality image at low cost, and an image forming apparatus provided with such an image reading apparatus is also inexpensive and has high image quality. An image can be formed.

  Furthermore, even when an image transmission / reception apparatus (FAX) is used, it is possible to transmit an inexpensive and high-quality image.

Sectional drawing which shows the outline | summary of the image forming apparatus used as the object which uses the reading module and image reading apparatus which concern on this invention The perspective view which shows the structure of one Example of the reading module which concerns on this invention. Similarly, an enlarged sectional view of the main part Top view (a) and front view (b) of lighting unit Arrangement of the substrate as seen from the direction of light emission from the LED of the light emitter Diagram showing how to adjust the lighting position

Explanation of symbols

1: Reading module 2: Contact glass 3: Illumination unit 4: Light emitter 5: Adjustment mirror 6: Illumination lens group 7: Condensing reflection mirror 8: Mirror group 9: Imaging lens 10: Reading unit 11: One-dimensional CCD
DESCRIPTION OF SYMBOLS 12: Board | substrate 13: Running body 14: Case of reading module 15: LED array 100: Image forming part 200: Paper feeding part 300: Image reading apparatus 400 of this invention 400: Original paper feeding part PR: Rotary parabolic mirror CA2 : Main illumination lens CA1: Main condenser lens M: Reading area width L: Main integrated lens

Claims (17)

In the reading module, the reflected light from the illuminated original is reduced and imaged on an image sensor by an imaging lens system, the image is read one-dimensionally, and a two-dimensional image is read by scanning the image. A reading module comprising the light source for illumination on a substrate on which is mounted. The reading module according to claim 1, comprising a plurality of the light sources. 3. The reading module according to claim 2, further comprising a condensing function member that condenses a plurality of light beams emitted from the plurality of light sources on the document surface. 3. The reading module according to claim 2, further comprising an optical system for superimposing a plurality of light beams emitted from the plurality of light sources on the document surface. 5. The reading module according to claim 1, wherein an LED is used as the light source. 6. The reading module according to claim 5, wherein at least one of three colors of light of red, green and blue can be emitted by using at least three LEDs as the light source. 7. The reading module according to claim 6, wherein the number of LEDs of the three colors red, green, and blue is such that the number of reds ≦ the number of blues ≦ the number of greens. 8. The reading module according to claim 6, wherein power supplied to the red, green, and blue LEDs is set such that power to red ≦ power to blue ≦ power to green. 9. 9. The reading module according to claim 1, wherein the light source is mounted on a substrate surface on the back side of the substrate surface on which the imaging element is mounted. 10. The reading module according to claim 9, wherein the image sensor and the light source are mounted at a position that does not overlap with a projection position of the substrate surface. 11. The reading module according to claim 1, further comprising a mirror that reflects the illumination light emitted from the light source and guides the illumination light to the original surface, and the adjustment of the illumination position can be adjusted by moving the mirror. A reading module. 12. The reading module according to claim 11, wherein the illumination position can be adjusted after adjusting the reading optical axis of the image sensor. 11. The reading module according to claim 1, wherein the illumination light emitted from the light source is parallel light or substantially parallel light, and the illumination immediately after being emitted from the read optical axis immediately before entering the image sensor and the light source. A reading module characterized in that the optical axis of light is parallel or substantially parallel. 14. The reading module according to claim 11, wherein a mirror that reflects illumination light emitted from the light source and guides it to the document surface, and an optical system that superimposes a plurality of light beams emitted from the light sources on the document surface. And a condensing function member that condenses a plurality of light beams emitted from each light source on the original surface, and forms a sub module, and the sub module can be moved together when adjusting the optical axis of the illumination light A reading module characterized by comprising: 15. The reading module according to claim 1, wherein the image pickup device is a CCD. An image reading apparatus comprising the reading module according to claim 1. An image forming apparatus comprising the image reading apparatus according to claim 16.