JP2006121555A - Illuminating device, image reading device and image formation apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the number of components, and to increase the generation efficiency of components to be used, and to obtain whitened rays of light at low costs as the illuminating light source of an illuminating device. <P>SOLUTION: The illuminating light source of an illuminating light source 18 which emits the rays of light to the original surface of an original positioned on a contact glass 12 is configured to emit whitened rays of light by a light emitting diode 40 which emits homogeneous rays of light by an electroluminescence phenomenon and translucent members containing substances for generating a photoluminescence phenomenon to be excited by the rays of light to be emitted from the light emitting diode 40 to emit the rays of light for covering the light emitting face of the light emitting diode. Also, this illuminating light source is configured to emit the whitened rays of light by composing both the substances by using the same substance. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an illumination device, an image reading device, and an image forming apparatus.

  2. Description of the Related Art Conventionally, an image reading device such as a scanner has a light source that is positioned on a contact glass and emits light toward a document surface of a document to be scanned, and is reflected along the scanning optical axis after being reflected by the document surface. The traveling reading light is coupled to a photoelectric conversion element such as a CCD (Charge Coupled Device) via optical means such as a mirror or a lens to read a document image.

  As a light source of such an image reading apparatus, a light source such as a fluorescent lamp or a xenon lamp is used. For example, this xenon lamp has little blue output with a short wavelength. Therefore, in order to increase the blue output, it is necessary to increase the amount of light of the entire illumination light source. However, if the amount of light of the entire illumination light source is increased, for example, the output of long wavelength red and the like also increases.

  Here, the CCD as the photoelectric conversion element is highly sensitive to, for example, red having a long wavelength, and also sensitive to an infrared region that is not necessary for reading a document image. For this reason, when the amount of light in the red or infrared region increases as the blue output increases, the light of red or the like is received together with the blue light, so that the temperature of the CCD rises and causes heat generation. For this reason, when a xenon lamp is used as an illumination device, a member (for example, an infrared cut filter) or the like for excluding unnecessary light in the infrared region while increasing the amount of light of the xenon lamp is used. However, this increases costs for measures against temperature and measures for receiving necessary light. In consideration of these points, an example in which white light is obtained using an LED (Light Emitting Diode) in recent years and this white light is used as a light source can be seen (see Patent Document 1).

JP 11-317108 A

  As a method for obtaining white light, first, there is a method in which each color LED of R (red), B (blue), and G (green) is caused to emit light simultaneously. By emitting the three colors simultaneously, the colors are mixed and become white. However, color unevenness tends to occur and it is difficult to maintain white light.

  The method described in Patent Document 1 is composed of a fluorescent resin prism in which a blue LED and a fluorescent dye are dissolved in a transparent resin, and white light is obtained by this combination. When the blue LED emits light, the light irradiates the fluorescent dye of the fluorescent resin prism, and light is emitted by the fluorescent dye. This light and the light of the blue LED that has passed through the fluorescent resin prism without colliding with the fluorescent dye are mixed and emitted as white light.

  However, in order to emit white light, the configuration of the blue LED and the fluorescent resin prism is required, so that the number of parts constituting the illumination device becomes plural, the part cost increases, and plural parts are added. Because of the combination, the variation in assembly accuracy increases.

  In addition, depending on the distance between the blue LED and the fluorescent resin prism, part of the light emitted from the blue LED may not enter the fluorescent resin prism, and the light emission of the blue LED may not be fully utilized. . For this reason, the blue LED used in combination with the fluorescent resin prism must be a blue LED with higher directivity, and the range of component selection is narrowed.

  Further, since the fluorescent resin prism here is one in which red and green fluorescent dyes are dissolved in a transparent resin, variations occur in the blending of the red and green fluorescent dyes.

  The object of the present invention is to eliminate the light emission members of the three primary colors of R (red), B (blue), and G (green), reduce the number of components, and minimize the light emission loss of the blue LED, thereby improving the light emission efficiency. The white light can be obtained at low cost.

  The illumination device according to claim 1 is an illumination device including an illumination light source that is located on the contact glass and emits light toward a document surface of a document to be read, wherein the illumination light source includes electroluminescence. A light-emitting diode that emits a single color by a phenomenon, a light-transmitting member that covers a light-emitting surface of the light-emitting diode, containing a substance that generates a photoluminescence phenomenon that is excited by light emitted from the light-emitting diode to emit light; The whitened light is emitted.

  According to a second aspect of the present invention, in the illuminating device according to the first aspect, of the illumination light source, the light emitting diode is formed of a GaN-based material, and the substance causing the photoluminescence phenomenon is formed of a YAG-based material. It is a phosphor.

  The illumination device according to claim 3 is an illumination device including an illumination light source that is positioned on the contact glass and emits light toward a document surface of a document to be read, wherein the illumination light source is a photoluminescence The whitened light is emitted by a substance that causes the phenomenon and a light emitting diode that is the same substance as the above substance and emits a single color by the electroluminescence phenomenon.

  According to a fourth aspect of the present invention, in the illumination device according to the third aspect, the illumination light source is formed of a ZnSe-based light emitting diode and a ZnSe single crystal substrate.

  According to a fifth aspect of the present invention, in the illuminating device according to any one of the first to fourth aspects, a plurality of the illumination light sources are provided along a main scanning direction during document reading.

  According to a sixth aspect of the present invention, there is provided an illumination device according to any one of the first to fifth aspects, a plurality of optical means for receiving and reflecting light reflected from a document of light emitted from the illumination device, and a document. And a photoelectric conversion element that receives the reflected light.

  According to a seventh aspect of the present invention, in the image reading device according to the sixth aspect, the light emitted from the illumination light source of the illuminating device is positioned in front of the emission direction, and the light emitted from the illumination light source is placed on the contact glass. A light guide member that guides light toward the original along the main scanning direction.

  According to an eighth aspect of the present invention, there is provided an image forming apparatus comprising the image reading apparatus according to the sixth or seventh aspect.

  According to the invention of claim 1, as a configuration for obtaining the white light necessary for the lighting device, a configuration is adopted in which the light emitting surface of the light emitting diode is covered with a translucent member containing a substance that causes a photoluminescence phenomenon. R (red), B (blue), and G (green) are not required for the light emitting members of the three primary colors, the number of components is small, and the light emission loss of the blue LED is minimized, and therefore the light emission efficiency is good. White light can be obtained at low cost.

  According to a second aspect of the present invention, in the illumination light source in the illuminating device according to the first aspect, the light emitting diode is formed of a GaN-based material, and is a photo that emits light when excited by light emitted from the light emitting diode. Since the phosphor, which is a substance that causes the luminescence phenomenon, is made of a YAG-based material, the output of the short wavelength of blue can be increased without increasing the output of long wavelength such as red. Can be prevented.

  According to the invention of claim 3, since the light emitting diode necessary for obtaining the white light necessary for the lighting device and the material that causes the photoluminescence phenomenon are formed of the same material, R (red) B ( Blue) G (green) three primary colors of light-emitting members are not required, the number of components is small, and the light emission loss of blue LEDs is minimized. Can be obtained.

  According to the invention of claim 4, since the illumination light source in the illumination device of claim 3 is formed of a ZnSe-based light emitting diode and a ZnSe single crystal substrate, the output of a long wavelength such as red is not increased. Since the output of the blue short wavelength can be increased, the heat generation of the CCD can be prevented.

  According to a fifth aspect of the present invention, in the illumination device according to any one of the first to fourth aspects, a plurality of the illumination light sources are provided along the main scanning direction at the time of document reading. All of the light emitted from is effectively used to illuminate the document surface.

  According to an image reading apparatus of a sixth aspect of the present invention, the illumination apparatus according to any one of the first to fifth aspects, and a plurality of light beams reflected and reflected from the original of the light emitted from the illumination apparatus are received and reflected. Since the optical means and the photoelectric conversion element that receives the reflected light from the original are included, it is possible to read an image under stable illumination performance.

  According to a seventh aspect of the present invention, in the image reading apparatus according to the sixth aspect, the light emitted from the illumination light source of the illumination device is positioned in front of the emission direction, and the light emitted from the illumination light source is the contact. Since the light guide member that guides light along the main scanning direction toward the original on the glass is provided, all light emitted from the light source and passing through the light guide member illuminates the original surface. It is used effectively.

  According to the image forming apparatus of the eighth aspect of the invention, since the image reading apparatus according to the sixth or seventh aspect is provided, an image can be formed according to a stable image reading result by the image reading apparatus. .

  A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a schematic front view showing the internal structure of a full-color copying machine 1 which is an image forming apparatus to which the present invention is applied.

  An image forming unit 3 for forming a color image is provided at the center in the apparatus main body 2 of the copying machine 1. The image forming unit 3 includes four drum-shaped photoconductors 4 that are spaced apart at equal intervals and arranged in parallel in the horizontal direction. The image forming units 3 are arranged on the outer periphery of each photoconductor 4 and are electrophotographic. An electrostatic latent image is formed by exposing the outer peripheral surface of the charging roller 5, the developing device 6, the cleaning device 7, and the uniformly charged photoreceptor 4 that forms a toner image on the outer peripheral surface with a laser beam corresponding to the image data. An exposure device 8 to be formed, an intermediate transfer belt 9 on which a color toner image is formed by sequentially transferring toner images formed on the outer peripheral surface of each photoconductor 4, and a color toner image on the intermediate transfer belt 9 as a recording medium The transfer roller 10 is configured to transfer to S. The four photoreceptors 4 respectively form Y (yellow), M (magenta), C (cyan), and B (black) toner images.

  An ADF 11 that automatically feeds a document to be read and an image reading device 13 that reads a document automatically fed by the ADF 11 or a document placed on the contact glass 12 are arranged on the upper part of the apparatus main body 2. . The image reading device 13 includes first and second traveling bodies 14 and 15 that can travel at a speed of 2: 1 in parallel with the contact glass 12, a lens 16, a CCD 17 that is a photoelectric conversion element, and the like. The first traveling body 14 includes an illuminating device 18 for illuminating the document surface of the document placed on the contact glass 12 or the document conveyed by the ADF 11, and is reflected on the document surface to be a reading optical axis. A first mirror 19 that reflects the light traveling along is mounted. The second traveling body 15 is equipped with a second mirror 20 and a third mirror 21 that further reflect the light reflected by the first mirror 19. A lens 16 and a CCD 17 are arranged in front of the traveling direction of the reading light sequentially reflected by the first to third mirrors 19, 20, and 21.

  A plurality of, for example, four-stage paper cassettes 24 for storing the recording medium S are provided at the lower part of the apparatus main body 2. The recording media S stored in these paper cassettes 24 are separated and fed one by one by a pickup roller 25 and a feed roller 26, and the separated and fed paper is a paper transport path 27 provided in the apparatus main body 2. It is conveyed along. A registration roller 28, a transfer roller 10, a fixing device 29, a paper discharge roller 30, and the like are disposed along the paper conveyance path 27.

  In such a configuration, laser light corresponding to the image data of each color (yellow Y, magenta M, cyan C, and black B) is emitted from the semiconductor laser of the exposure device 8 according to the reading result of the image reading device 13, An electrostatic latent image is formed by exposing the outer peripheral surface of each photoreceptor 4 to which the laser light is uniformly charged by the charging roller 5. By supplying each color toner from each developing device 6 to the electrostatic latent image, each color toner image is formed. The toner images on the respective photoconductors 4 are sequentially transferred onto an intermediate transfer belt 9 that moves in synchronization with the photoconductors 4, and a color toner image is formed on the intermediate transfer belt 9.

  On the other hand, before and after the start of the image forming operation in the image forming unit 3, the separation and feeding of the sheet is started from the sheet cassette 24, and the sheet that is separated and fed through the sheet conveyance path 27 is intermittent. The registration roller 28 is driven to rotate at the timing when the color toner image on the intermediate transfer belt 9 is transferred to an appropriate position on the recording medium S.

  The color toner image on the intermediate transfer belt 9 is transferred onto the recording medium S when the recording medium S conveyed by the rotation of the registration roller 28 passes between the intermediate transfer belt 9 and the transfer roller 10. Is done. The color toner image transferred onto the recording medium S is fixed on the recording medium S in the process of passing through the fixing device 29, and the recording medium on which the color toner image is fixed is discharged onto the discharge tray 31 by the discharge roller 30. Paper.

  Under such a configuration, characteristic portions of the present embodiment will be described in order.

  FIG. 2 is an enlarged front view of the lighting device 18 and the first mirror 19 mounted on the first traveling body 14. FIG. 3 is a perspective view showing the lighting device 18. The illumination device 18 includes a rectangular white LED 40 and a long substrate 41 that are a plurality of light sources.

  The white LEDs 40 are linearly arranged on the substrate 41 at substantially equal intervals, and this arrangement direction coincides with the main scanning direction of the original when the illumination device 18 is incorporated in the image reading device 13 and image reading is performed. Yes. In addition, a wiring pattern (not shown) is formed on the substrate 41 so as to connect the fixed white LED 40 so that energization is possible. Further, although not shown, peripheral circuit elements including a current limiting resistor and the like are connected to the wiring pattern and fixed to the substrate 41. In the present embodiment, the case where the white LED 40 is provided in a straight line is described as an example, but a plurality of lines of white LEDs along a direction that coincides with the main scanning direction of the document at the time of image reading is described. May be provided.

  The light emitted from the white LED 40 irradiates a part of the contact glass 12, is reflected by the document surface of the document placed on the contact glass 12, travels along the reading optical axis, and is reflected by the first mirror 19. Reflected.

  FIG. 4 is a schematic view showing the white LED 40 cut along the line AA. The white LED 40 includes a blue LED 42 formed of a GaN-based material and a fluorescent resin 44 in which a YAG phosphor 43 is dispersed and melted. That is, the blue LED 42 is placed on the bottom of the depression provided in the white LED 40, and the depression is filled with the fluorescent resin 44 so as to cover the blue LED 42. Thus, since the illumination device is integrated and configured by covering the blue LED 42 with the fluorescent resin 44, the number of components is small, and the light emission loss of the blue LED can be minimized. Luminous efficiency is good and white light can be obtained at low cost.

  Next, a process in which the white LED 40 emits light will be described. An electric field is applied to the blue LED 42 using a wiring (not shown). The blue LED 42 emits light by an applied electric field (electroluminescence phenomenon). The emitted light passes through the fluorescent resin 44 as it is and is emitted to the outside as blue light 45 (light represented by a solid line arrow in FIG. 4) and the YAG phosphor melted in the fluorescent resin 44. The light is absorbed into the light 43 and converted into yellow light 46 (light represented by a dotted arrow in FIG. 4) (photoluminescence phenomenon), which is emitted to the outside. These blue light and yellow light are mixed to become white light 47.

  In FIG. 4, only two of the YAG phosphors 43 that are normally melted in the fluorescent resin 44 are taken out and shown in a large scale in order to facilitate understanding of the explanation.

  FIG. 5 is a schematic view showing another form of the white LED, cut like the white LED described in FIG.

  The white LED 50 is placed on a substrate 41 and is composed of a ZnSe substrate 51 and a light emitting structure (thin film) 52 thereon. The ZnSe substrate 51 is doped with, for example, iodine or aluminum, and these dopants 53 emit light by applying predetermined light. The thin film 52 is a ZnSe film grown on the ZnSe substrate 51 and becomes a blue LED.

  In the light emission process of the white LED 50, first, when an electric field is applied to the thin film 52 (blue LED) using a wiring (not shown), the thin film 52 (blue LED) emits light. The emitted light 54 is emitted to the outside, and a part of the light enters the ZnSe substrate 51 and prompts the dopant 53 to emit light. The light 55 thus emitted is reflected on the bottom surface or directly emitted to the outside beyond the thin film 52. The light 54 of the thin film 52 (blue LED) and the light 55 emitted from the dopant 53 are mixed to produce white light 56. That is, the ZnSe substrate 51 plays the same role as the phosphor, and the same substance ZnSe is used for both the light emitter and the phosphor.

  Therefore, by adopting the white LED 50 as the lighting device, the number of parts is small and the light emission loss of the blue LED can be minimized, so that the light emission efficiency is good and white light can be obtained at low cost. it can.

  Note that in FIG. 5, a dopant 53 such as iodine doped in the ZnSe substrate 51 is shown so as to help understand the explanation.

  A second embodiment of the present invention will be described with reference to FIGS. FIG. 6 is an enlarged front view of the lighting device 18, the first mirror 19, and the light guide member 60 mounted on the first traveling body 14. FIG. 7 is a perspective view showing the lighting device 18 in an exploded manner into the substrate 41, the white LEDs 40 and 50, and the light guide member 60. In addition, since the member which attached | subjected the same code | symbol as 1st Embodiment has already demonstrated, it abbreviate | omits here.

The light guide member 60 is made of, for example, a transparent resin (acrylic, polycarbonate, or the like) or glass, and is positioned forward of the light emitted from the white LEDs 40 and 50 toward the original. Light emitted from the white LEDs 40 and 50 in a diffused state enters the light guide member 60 and travels through the light guide member 60 to prevent further light from diffusing. Irradiated toward the document surface. By using the light guide member 60, the light emitted from the white LEDs 40, 50 can be led to the direction in which the light is collected as much as possible, that is, the original surface.

1 is a schematic front view showing an internal structure of a full-color copying machine which is an image forming apparatus to which the present invention is applied. It is the front view which expanded and represented the illuminating device and 1st mirror which are mounted in the 1st traveling body. It is a perspective view which shows an illuminating device. It is the schematic diagram which cut | disconnected and showed white LED along the AA line. It is a schematic diagram which cut | disconnects and shows another form of white LED. It is the front view which expanded and represented the illuminating device, the 1st mirror, and light guide member which are mounted in the 1st traveling body. It is a perspective view which decomposes | disassembles and shows an illuminating device to a board | substrate, white LED, and a light guide member.

Explanation of symbols

12 Contact glass 14 1st traveling body 18 Illumination device 19 1st mirror 40 White LED
41 Substrate 50 White LED
60 Light guide member

Claims (8)

An illumination device having an illumination light source that emits light toward a document surface of a document to be read located on a contact glass,
The illumination light source is
A light emitting diode that emits a single color by electroluminescence, and
Containing a substance that generates a photoluminescence phenomenon that is excited by light emitted from the light emitting diode to emit light, and covers a light emitting surface of the light emitting diode;
A lighting device characterized in that it emits whitened light.   2. The illumination according to claim 1, wherein, among the illumination light sources, the light emitting diode is formed of a GaN-based material, and a substance that causes a photoluminescence phenomenon is a phosphor formed of a YAG-based material. apparatus. An illumination device having an illumination light source that emits light toward a document surface of a document to be read located on a contact glass,
The illumination light source is
A substance that causes a photoluminescence phenomenon;
A light-emitting diode that is the same substance as the substance and emits a single color by an electroluminescence phenomenon;
A lighting device characterized in that it emits whitened light.   4. The illumination device according to claim 3, wherein the illumination light source is formed of a ZnSe-based light emitting diode and a ZnSe single crystal substrate.   5. The illumination device according to claim 1, wherein a plurality of illumination light sources are provided along a main scanning direction during document reading. A lighting device according to any one of claims 1 to 5;
A plurality of optical means for receiving and reflecting reflected light from the original of the light emitted from the illumination device;
A photoelectric conversion element that receives the reflected light through the optical device;
An image reading apparatus.   The illumination device is positioned in front of the emission direction of the light emitted from the illumination light source, and guides the light emitted from the illumination light source so as to illuminate the original on the contact glass along the main scanning direction. The image reading apparatus according to claim 6, further comprising a light guide member. An image forming apparatus comprising the image reading apparatus according to claim 6.

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