JP2009239434A - Lighting device for reading document image, image reading unit, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce useless power consumption while controlling deterioration in the image quality of a read-out document image. <P>SOLUTION: A lighting device (A1, A1', A1") for reading a document image comprises a light source (1, 1') emitting irradiation light with which the entire region of a document (Gi) on which an image is recorded is irradiated in the width direction, wherein the light source (1, 1') has a planar light-emitting portion (1a, 1a') and the light-emitting area (Sb) of the light-emitting portion (1a, 1a') corresponding to the opposite ends of the document (Gi) in the width direction is larger than the light-emitting area (Sa) of the light-emitting portion (1a, 1a') corresponding to the central part of the document in the width direction. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

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

Conventionally, the irradiation light emitted from the light source is reflected by the original on the platen glass, the reflected light reflected is reflected by the reflecting mirror, converged by the imaging lens, and imaged by the solid-state imaging device, 2. Description of the Related Art An image reading device that reads an image of a document, a so-called scanner is known.
In the image reading apparatus, since the reflected light from the original is focused by the imaging lens, the amount of the reflected light decreases as it approaches the both ends of the original in the width direction according to the cosine fourth law. It is known that images are taken in a dark state. Note that the cosine fourth power law is an incident angle incident on the solid-state imaging device, that is, a so-called angle of view, θ, an illuminance of light before incidence is L _0, and an illuminance of light after incidence is L, The said illuminance L is a law shown by the following formula | equation (1).
L = L ₀ cos ⁴ θ (1)

For this reason, in the image reading apparatus, by integrating a constant to the illuminance L of the reflected light at both ends in the width direction, the illuminance L of the reflected light at the both ends in the width direction and the central portion in the width direction is made the same. A so-called shading process or a light-shielding plate is disposed upstream of the reflected light in the incident direction with respect to the imaging lens, and the reflected light at the central portion in the width direction is shielded, thereby both ends in the width direction. In general, a process of making the illuminances L of the reflected light at the central portion and the central portion in the width direction the same, so-called sagittal stop, is generally performed.
That is, in the conventionally known image reading device, the imaged noise component may be amplified by the constant, and the reflected light is shielded to reduce the absolute light amount in the central portion in the width direction. By performing the sagittal stop that generates waste of energy of the light source, the image is corrected so that both ends in the width direction do not become dark.

Further, in recent years, in the image reading apparatus, organic electroluminescence, so-called organic EL light source using organic EL, has begun to be adopted in order to reduce the size of the light source and reduce the power consumption and heat generation amount of the light source.
As for the image reading apparatus having the organic EL light source, for example, a technique described in Patent Document 1 below is known.

  In Japanese Patent Laid-Open No. 2000-115470 as Patent Document 1, the irradiation light irradiated from a light source is reflected by the document (1) on the document table glass (2), and the reflected light is reflected by a reflection mirror ( 6, 7), the light is reflected by the imaging lens (8), and is read by the photoelectric conversion element (9). The light source is made up of two light emitting regions facing the document (1). Describes a technique comprising a so-called EL lamp (11), a U-shaped electroluminescence lamp having a light emitting surface (12) having a slit and a slit portion (13) as a sandwiching portion between the two light emitting regions. ing.

In Patent Document 1, the light emitting surface (12) is arranged in parallel to the document (1) and the document table glass (2), and the reflected light is transmitted from the slit portion (13) to the document. By leading out to the reflection mirror (6) provided vertically below the slit portion (13), in the original (1), the center portion of the slit portion (13) is uniform over a wide area. A technique for forming a light quantity distribution is described.
That is, Patent Document 1 describes a technique for irradiating a wide range in the width direction and the length direction of the document (1) with the same amount of light by using the two light emitting regions without considering the cosine fourth power law. .

JP 2000-115470 A ("0003", "0004", "0014" to "0018", FIGS. 1 to 3, 6, and 7)

  It is a technical object of the present invention to reduce wasteful power consumption while reducing deterioration in image quality of a read original image.

In order to solve the technical problem, an illumination device for reading a document image according to claim 1 comprises:
A light source that emits irradiation light that is applied to the entire width direction of a document on which an image is recorded, the light source having a planar light-emitting portion that emits light, and light emission of the light-emitting portion corresponding to both ends in the width direction of the document The light source having the light emitting portion having an area larger than a light emitting area of the light emitting portion corresponding to a central portion in the width direction of the document;
It is provided with.

According to a second aspect of the present invention, in the document image reading illumination device according to the first aspect,
In accordance with the cosine fourth power law, the light source set so that the light emitting area increases from the width direction central portion of the light emitting portion toward the both ends in the width direction,
It is provided with.

According to a third aspect of the present invention, in the document image reading illumination device according to the first or second aspect,
The light source having the light emitting portion in which organic electroluminescence elements as light emitting elements that emit light are arranged in a plane,
It is provided with.

According to a fourth aspect of the present invention, in the illumination device for reading a document image according to any one of the first to third aspects,
A transparent, planar transparent substrate that supports the light source;
A transparent opening formed along an outer edge of the light emitting portion and transmitting the irradiation light emitted from the light emitting portion; a light shielding portion provided along an outer shape of the transparent substrate; and A light-shielding member disposed between the document and
It is provided with.

The invention according to claim 5 is the illumination device for reading a document image according to any one of claims 1 to 4,
A planar base for supporting the light source, wherein the base is formed along an outer edge of the light emitting part and transmits the irradiation light emitted from the light emitting part; The base having the light leakage prevention part formed along the outer shape and preventing light leakage from the outer edge of the light emitting part to the outside,
It is provided with.

In order to solve the technical problem, an image reading apparatus according to claim 6 is provided.
The document image reading illumination device according to any one of claims 1 to 5, wherein the irradiation light is applied to the entire width direction of the document on which the image is recorded.
An imaging member that forms an image of reflected light reflected from the document irradiated with the irradiation light;
An imaging member that images the reflected light imaged by the imaging member;
It is provided with.

In order to solve the technical problem, an image forming apparatus according to claim 7 is provided.
The image reading apparatus according to claim 6, wherein the image is read by irradiating the irradiation light over the entire width direction of the document on which the image is recorded;
An image recording apparatus for recording the read image on a medium;
A medium conveying device for conveying the medium;
It is provided with.

According to the first aspect of the present invention, it is possible to reduce wasteful power consumption while reducing deterioration in image quality of a read document image, compared to a case where the configuration of the present invention is not provided.
According to the second aspect of the present invention, when the reflected light reflected from the original is imaged, the image in the entire width direction of the original can be read more clearly than when the configuration of the present invention is not provided. it can.

According to the third aspect of the present invention, the light source can be reduced in size, reduced in power consumption, and reduced in calorific value, while maintaining the light quantity of the irradiation light, compared with the case where the configuration of the present invention is not provided.
According to the fourth aspect of the present invention, it is possible to prevent the light leaked outward from the outer edge of the light emitting portion from being diffusely reflected and the like, and to be applied to the original, and the light quantity distribution in the entire width direction of the original is obtained. And a distribution corresponding to the shape of the light emitting part.
According to the fifth aspect of the present invention, compared to the case without the configuration of the present invention, it is possible to reduce the light leaked outward from the outer edge of the light emitting unit from being irregularly reflected and irradiating the original. The light amount distribution in the entire width direction of the document can be easily made to correspond to the shape of the light emitting portion.

According to the sixth aspect of the present invention, it is possible to reduce wasteful power consumption while reducing deterioration in the image quality of the read document image as compared with the case where the configuration of the present invention is not provided.
According to the seventh aspect of the present invention, it is possible to reduce wasteful power consumption while reducing the deterioration of the image quality of the image recorded on the medium as compared with the case where the configuration of the present invention is not provided.

Next, examples which are specific examples of embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following examples.
In order to facilitate understanding of the following description, in the drawings, the front-rear direction is the X-axis direction, the left-right direction is the Y-axis direction, the up-down direction is the Z-axis direction, and arrows X, -X, Y, -Y, The direction indicated by Z and -Z or the indicated side is defined as the front side, the rear side, the right side, the left side, the upper side, the lower side, or the front side, the rear side, the right side, the left side, the upper side, and the lower side, respectively.
In the figure, “•” in “○” means an arrow heading from the back of the page to the front, and “×” in “○” is the front of the page. It means an arrow pointing from the back to the back.
In the following description using the drawings, illustrations other than members necessary for the description are omitted as appropriate for easy understanding.

FIG. 1 is an overall explanatory view of an image forming apparatus according to Embodiment 1 of the present invention.
In FIG. 1, the image forming apparatus U includes an automatic document feeder U1 and an image forming apparatus body U2 that supports the automatic document feeder U1 and has a transparent document reading surface PG at the upper end.
The automatic document feeder U1 includes a document feeding unit TG1 that accommodates a plurality of documents Gi to be copied and a document feeding position TG1 that is fed from the document feeding unit TG1 and passes through a document reading position on the document reading surface PG. And a document discharge portion TG2 from which the document Gi conveyed is discharged.
The image forming apparatus main body U2 includes an operation unit UI through which a user inputs an operation command signal for starting an image forming operation, an exposure optical system A, and the like.

Reflected light from the document Gi conveyed on the document reading surface PG by the automatic document feeder U1 or the document Gi manually placed on the document reading surface PG passes through the exposure optical system A to the imaging member. The image is picked up by a solid-state image pickup device CCD as an example, and is converted into electric signals of red R, green G, and blue B.
The image information conversion unit IPS converts the RGB electrical signals input from the solid-state imaging device CCD into black K, yellow Y, magenta M, and cyan C image information and temporarily stores them, and stores the image information in a predetermined manner. Is output to the latent image forming apparatus driving circuit DL as image information for forming a latent image.
When the original image is a single color image, so-called monochrome, image information of only black K is input to the latent image forming device driving circuit DL.

The latent image forming device drive circuit DL has drive circuits for respective colors Y, M, C, and K (not shown), and signals corresponding to input image information are arranged for each color at a predetermined time. Output to the image forming apparatuses LHy, LHm, LHc, and LHk.
The automatic document feeder U1, the document reading surface PG, the exposure optical system A, the solid-state imaging device CCD, the image information conversion unit IPS, and the like constitute the image reading device (U1 + PG + A + CCD + IPS) of the first embodiment.

FIG. 2 is an enlarged explanatory view of a main part of the image forming apparatus according to the first embodiment.
Visible image forming devices Uy, Um, Uc, and Uk arranged at the center of the image forming device U in the gravitational direction are devices that form visible images of colors Y, M, C, and K, respectively.
The Y, M, C, and K latent image writing lights (not shown) emitted from the latent image writing light sources of the latent image forming devices LHy to LHk respectively enter the rotating image carriers PRy, PRm, PRc, and PRk. To do. In Example 1, the latent image forming apparatuses LHy to LHk are configured by a so-called LED: Light Emitting Diode array.
The Y visible image forming device Uy includes a rotating image carrier PRy, a charger CRy, a latent image forming device LHy, a developing device Gy, a transfer device T1y, and an image carrier cleaner CLy. In the first exemplary embodiment, the image carrier PRy, the charger CRy, and the image carrier cleaner CLy are configured as an image carrier unit that can be integrally attached to and detached from the image forming apparatus main body U2.
The visible image forming apparatuses Um, Uc, Uk are all configured in the same manner as the Y visible image forming apparatus Uy.

1 and 2, the image carriers PRy, PRm, PRc, and PRk are charged by their respective chargers CRy, CRm, CRc, and CRk, and then at image writing positions Q1y, Q1m, Q1c, and Q1k. An electrostatic latent image is formed on the surface of the latent image writing light. The electrostatic latent images on the surfaces of the image carriers PRy, PRm, PRc, and PRk are developed in the developing regions Q2y, Q2m, Q2c, and Q2k as a developer roll as an example of a developer carrier of the developing devices Gy, Gm, Gc, and Gk. A toner image as an example of a visible image is developed with the developer held in R0y, R0m, R0c, and R0k.
The developed toner image is conveyed to primary transfer regions Q3y, Q3m, Q3c, and Q3k that are in contact with an intermediate transfer belt B as an example of an intermediate transfer member. The primary transfer units T1y, T1m, T1c, and T1k disposed on the back side of the intermediate transfer belt B in the primary transfer regions Q3y, Q3m, Q3c, and Q3k are supplied with a predetermined value from a power supply circuit E controlled by the control unit C. At this time, a primary transfer voltage having a polarity opposite to the charging polarity of the toner is applied.

  The toner images on the image carriers PRy to PRk are primarily transferred onto the intermediate transfer belt B by the primary transfer devices T1y, T1m, T1c, and T1k. Residues and deposits on the surface of the image carrier PRy, PRm, PRc, PRk after the primary transfer are cleaned by the image carrier cleaner CLy, CLm, CLc, CLk. The cleaned surfaces of the image carriers PRy, PRm, PRc, and PRk are recharged by the chargers CRy, CRm, CRc, and CRk.

  Above the image carriers PRy to PRk, a belt module BM as an example of an intermediate transfer device that can move up and down and can be pulled out forward is disposed. The belt module BM includes the intermediate transfer belt B, a belt drive roll Rd as an example of an intermediate transfer body drive member, a tension roll Rt as an example of an intermediate transfer body stretching member, and a walking roll as an example of a meandering prevention member. Rw, an idler roll Rf as an example of a driven member, a backup roll T2a as an example of a secondary transfer region facing member, and the primary transfer units T1y, T1m, T1c, T1k. The intermediate transfer belt B can be rotated by belt support rolls Rd, Rt, Rw, Rf, T2a as an example of an intermediate transfer member support member constituted by the rolls Rd, Rt, Rw, Rf, T2a. It is supported by.

A secondary transfer roll T2b as an example of a secondary transfer member is disposed facing the surface of the intermediate transfer belt B in contact with the backup roll T2a, and a secondary transfer device T2 is configured by the rolls T2a and T2b. ing. Further, a secondary transfer region Q4 is formed in a region where the secondary transfer roll T2b and the intermediate transfer belt B are opposed to each other.
The single-color or multi-color toner images transferred in sequence on the intermediate transfer belt B by the primary transfer units T1y, T1m, T1c, and T1k in the primary transfer areas Q3y, Q3m, Q3c, and Q3k are the secondary transfer areas. Transported to Q4.
The primary transfer units T1y to T1k, the intermediate transfer belt B, the secondary transfer unit T2, and the like constitute a transfer device T1 + T2 + B according to the first exemplary embodiment.
The image holders PRy to PRk, the developing devices Gy to Gk, the transfer device T1 + T2 + B, and the like constitute the image recording device (PRy to PRk + Gy to Gk + T1 + T2 + B) of Example 1.

  Below the visible image forming devices Uy to Uk, a pair of left and right guide rails GR as an example of a guide member is provided, and the guide rails GR are fed as an example of a paper feed container. The trays TR1 to TR3 are supported so as to be able to enter and exit in the front-rear direction. A recording sheet S as an example of a medium accommodated in the paper feed trays TR1 to TR3 is taken out by a pickup roll Rp as an example of a medium takeout member and separated one by one by a separating roll Rs as an example of a medium separating member. The The recording sheet S is transported along a sheet transport path SH, which is an example of a medium transport path, by a plurality of transport rolls Ra, which is an example of a medium transport member, and is disposed upstream of the secondary transfer region Q4 in the sheet transport direction. Is sent to a registration roll Rr as an example of the transferred transfer area conveyance timing adjusting member. The sheet conveying path SH, the sheet conveying roll Ra, the registration roll Rr, and the like constitute a medium conveying apparatus (SH + Ra + Rr).

The registration roll Rr conveys the recording sheet S to the secondary transfer area Q4 in time for the toner image formed on the intermediate transfer belt B to be conveyed to the secondary transfer area Q4. When the recording sheet S passes through the secondary transfer region Q4, the backup roll T2a is grounded, and the secondary transfer unit T2b has a polarity opposite to the toner charging polarity from the power supply circuit E controlled by the control unit C. A secondary transfer voltage is applied. At this time, the toner image on the intermediate transfer belt B is transferred to the recording sheet S by the secondary transfer device T2.
The intermediate transfer belt B after the secondary transfer is cleaned by a belt cleaner CLb as an example of an intermediate transfer body cleaner.

The recording sheet S on which the toner image is secondarily transferred has a fixing region Q5 which is a pressure contact region of a heating roll Fh as an example of a heating fixing member of the fixing device F and a pressure roll Fp as an example of a pressing fixing member. And heated and fixed when passing through the fixing region. The heat-fixed recording sheet S is discharged from a discharge roller Rh as an example of a medium discharge member to a discharge tray TRh as an example of a medium discharge portion.
Note that a release agent for improving the releasability of the recording sheet S from the heating roll Fh is applied to the surface of the heating roll Fh by a release agent coating device Fa.

  Above the belt module BM, developer cartridges Ky, Km, Kc, and Kk are disposed as an example of a developer supply container that stores yellow Y, magenta M, cyan C, and black K developers. The developers contained in the developer cartridges Ky, Km, Kc, and Kk are supplied from the developer supply path (not shown) to the developing devices Gy according to the consumption of the developer in the developing devices Gy, Gm, Gc, and Gk. , Gm, Gc, Gk. In Example 1, the developer is composed of a two-component developer including a magnetic carrier and a toner provided with an external additive.

In FIG. 1, the image forming apparatus U includes an upper frame UF and a lower frame LF, and the upper frame UF includes the visible image forming apparatuses Uy to Uk and the visible image forming apparatus Uy. A member arranged above -Uk, that is, a belt module BM and the like are supported.
The lower frame LF includes a guide rail GR that supports the paper feed trays TR1 to TR3 and the paper feed members that feed paper from the trays TR1 to TR3, that is, a pickup roll Rp, a separation roll Rs, A sheet conveying roll Ra and the like are supported.

FIG. 3 is an enlarged explanatory diagram of the image reading apparatus according to the first embodiment.
FIG. 4 is an enlarged explanatory view of the document image reading illumination device according to the first embodiment.
FIG. 5 is an enlarged explanatory view of an organic EL light source and a light shielding member of Example 1.
3 to 5, the exposure optical system A according to the first embodiment is reflected by a document image reading illumination device A <b> 1 that irradiates irradiation light over the entire width direction of the document Gi and the document Gi at the document reading position. A document image reading reflection device A2 that reflects the reflected light of the irradiation light, and an imaging optical system A3 as an example of an imaging member that forms an image of the reflected light.

  The document image reading illumination device A1 according to the first exemplary embodiment is slidable from the left end portion to the right end portion in the length direction of the document Gi, that is, in the left-right direction, as shown by the solid and broken lines in FIGS. A full-rate carriage FRC as an example of a light source support member supported by the motor. A transparent and flat transparent substrate K is supported inside the full rate carriage FRC of the first embodiment. An organic EL light source 1 as an example of a light source that emits the irradiation light is supported on the lower surface of the transparent substrate K.

In FIG. 5, the organic EL light source 1 of Example 1 has a light emitting portion 1a in which organic EL elements as examples of light emitting elements emitting light are arranged in a planar shape. The light emitting unit 1a according to the first exemplary embodiment is arranged in a state of extending in the front-rear direction, that is, the width direction of the document. In addition, about the structure of the said organic EL element, it describes in the patent document 1 etc., for example, Since it is well-known, detailed description is abbreviate | omitted.
Further, the light emitting unit 1a according to the first embodiment has a length in the left-right direction, that is, the length direction of the document Gi, as it goes from the central portion in the width direction of the light emitting unit 1a to both ends in the width direction. It is set in advance so as to be linearly long.

That is, as shown in FIG. 5, the light emitting unit 1 a has LA as the shortest central portion distance that is the shortest distance in the longitudinal direction at the central portion in the width direction of the light emitting portion 1 a, and the width direction of the light emitting portion 1 a. When the longest distance between both ends, which is the longest distance in the length direction at both ends, is LB, LB> LA is set in advance.
Therefore, in the light emitting unit 1a according to the first exemplary embodiment, the light emitting area Sb per unit length L0 in the width direction of the light emitting unit 1a corresponding to both ends in the width direction of the document Gi corresponds to the central portion in the width direction of the document Gi. The light emitting area 1a is larger than the light emitting area Sa per unit length L0 in the width direction.

Further, a light shielding member 2 that shields the irradiation light is supported on the upper surface side of the transparent substrate K of the first embodiment. The light shielding member 2 according to the first embodiment is provided along the outer periphery of the transparent substrate K, and a transmission port 2a that is formed along the outer edge of the light emitting unit 1a and transmits the irradiation light emitted from the light emitting unit 1a. A light shielding portion 2b.
The full rate carriage FRC has an angle at which the irradiation light diffused rightward without being irradiated on the original Gi facing the right side of the transparent substrate K is reflected toward the upper original Gi. The irradiation light reflecting plate 3 is supported. Further, a reflected light transmission port 4 is formed at an intermediate portion between the transparent substrate K and the light shielding member 2, and the irradiation light reflected by the document Gi is below the reflected light transmission port 4. A first reflecting mirror 6 is supported as an example of a first reflecting optical system that reflects the reflected light toward the left-side document image reading reflecting device A2.

Further, as shown by the solid line and the broken line in FIGS. 1 and 3, the document image reading reflection device A2 according to the first embodiment moves from the left end to the center in the left-right direction, that is, half of the full rate carriage FRC. A half-rate carriage HRC is provided as an example of a reflection optical system support member that is slidably supported by a distance. The half-rate carriage HRC according to the first exemplary embodiment includes a second reflecting mirror 7 as an example of a second reflecting optical system that reflects the reflected light reflected by the first reflecting mirror 6 downward, and the second reflecting mirror 7. A third example of a third reflecting optical system that is disposed below the reflecting mirror 7 and reflects the reflected light reflected by the second reflecting mirror 7 toward the imaging optical system A3 on the right side. A reflection mirror 8 is supported.
Further, the imaging optical system A3 according to the first exemplary embodiment includes a so-called imaging lens, and causes the reflected light thus formed to be incident on the right solid-state imaging device CCD.

(Operation of Example 1)
In the image reading apparatus (U1 + PG + A + CCD + IPS) of Embodiment 1 having the above-described configuration, when the document Gi is transported on the document reading surface PG by the automatic document transport device U1, the carriages FRC and HRC are stopped. In this state, the irradiation light is irradiated from the light emitting portion 1a of the organic EL light source 1 to the entire width direction of the document Gi. The reflected light corresponding to the image of the document Gi being conveyed passes through the reflected light transmitting port 4 and is reduced and imaged by the imaging optical system A3 via the reflecting mirrors 6 to 8, The image is picked up by the solid-state image sensor CCD.

  In the image reading apparatus (U1 + PG + A + CCD + IPS) of the first embodiment, when an image is manually read from the original Gi placed on the original reading surface PG, the width of the original Gi from the light emitting portion 1a of the organic EL light source 1 is read. The carriages FRC and HRC are slid in the longitudinal direction of the document Gi, that is, scanned, while irradiating the irradiation light over the entire direction. At this time, the full rate carriage FRC that supports the organic EL light source 1 is slid from the left end portion to the right end portion in the length direction of the document Gi so that the optical path lengths of the reflected light are the same, and The half-rate carriage HRC is slid from the left end portion in the length direction of the document Gi, which is a half of the movement distance of the full-rate carriage FRC, to the center portion. The solid-state image sensor CCD sequentially captures images of areas irradiated with irradiation light that moves in accordance with the slide movement of the carriages FRC and HRC.

  Therefore, in the solid-state imaging device CCD, the reflected light from the document Gi is imaged by the imaging lens A3, that is, the light flux of the reflected light is focused. In the image reading apparatus (U1 + PG + A + CCD + IPS) of the first embodiment, in the light emitting portion 1a of the organic EL light source 1, the width direction unit of the light emitting portion 1a corresponding to both widthwise ends of the document Gi shown in FIG. The light emitting area Sb per length L0 is larger than the light emitting area Sa per width direction unit length L0 of the light emitting section 1a corresponding to the central part in the width direction of the document Gi.

  Therefore, in the image reading apparatus (U1 + PG + A + CCD + IPS) according to the first embodiment, the light emission unit 1a irradiates the central portion in the width direction of the document Gi with the light amount irradiated to both ends in the width direction of the document Gi. It is larger than the amount of the irradiated light. As a result, even if the image reading apparatus (U1 + PG + A + CCD + IPS) of the first embodiment is influenced by the cosine fourth law by forming the reflected light from the document Gi by the imaging lens A3, The images at both ends in the width direction of the document Gi are picked up in a bright state, similar to the image at the center in the width direction of the document Gi. As a result, in the image forming apparatus U according to the first exemplary embodiment, compared with the conventionally known shading process, Japanese Patent Application Laid-Open No. H10-335, and the like, the image quality deterioration of the read image is reduced.

  In the image forming apparatus U of Example 1 having the above-described configuration, the organic EL element is arranged in a planar shape in the light emitting portion 1 a of the organic EL light source 1. Therefore, in the image reading apparatus (U1 + PG + A + CCD + IPS) of the first embodiment, the organic EL light source 1 is composed of the organic EL element, so that the amount of irradiation light is larger than that of a conventionally known tubular light source such as a fluorescent tube. It is possible to reduce the size of the light source, reduce power consumption, and reduce the amount of heat generated while maintaining

  In the image forming apparatus U of Example 1 having the above-described configuration, the light-emitting portion 1a can be configured as long as the organic EL elements are arranged in a planar shape. Therefore, the light-emitting areas Sa and Sb can be configured. As for Sb> Sa, the shape of the light emitting portion 1a can be freely modified. As a result, the image reading apparatus (U1 + PG + A + CCD + IPS) according to the first exemplary embodiment sets the shape of the light emitting unit 1a so that the amount of light increases from the central portion in the width direction of the document Gi toward both ends in the width direction. As a result, wasteful power consumption is reduced as compared with the conventionally known sagittal stop.

  Further, in the image forming apparatus U of Example 1 having the above-described configuration, the organic EL light source 1 is supported on the transparent substrate K. For this reason, the irradiation light emitted from the light emitting unit 1a may be irregularly reflected between the transparent substrate K and the original reading surface PG or within the transparent substrate K. In the document image reading illumination device A1, the light shielding member 2 shown in FIGS. 4 and 5 is supported on the transparent substrate K. That is, in the image reading apparatus (U1 + PG + A + CCD + IPS) according to the first embodiment, the irradiation light that has passed through the transmission port 2a is transmitted by the light shielding member 2 disposed between the transparent substrate K and the document reading surface PG. Light that irradiates the document Gi and leaks outward from the outer edge of the light emitting unit 1a is blocked by the light blocking unit 2b.

As a result, the light leaked outward from the outer edge of the light emitting unit 1a is prevented from being diffusely reflected and applied to the original document Gi, and the light amount distribution in the entire width direction of the original document Gi is The distribution corresponds to the shape. In other words, the light-emitting portions 1a are distributed so as to increase from the central portion in the width direction toward the both end portions in the width direction.
Therefore, in the image reading apparatus (U1 + PG + A + CCD + IPS) of Example 1, the light shielding member 2 disposed between the transparent substrate K and the original document Gi is not provided by the light shielding portion 2b of the light shielding member 2. Compared to the above, the image quality deterioration of the image to be read is reduced.

FIG. 6 is an enlarged explanatory view of the document image reading illumination apparatus according to the second embodiment and corresponds to FIG. 4 according to the first embodiment.
Next, the image forming apparatus U according to the second embodiment of the present invention will be described. In the description of the second embodiment, the same reference numerals are given to the components corresponding to the components of the first embodiment, and Detailed description is omitted. The second embodiment is different from the first embodiment in the following points, but is configured in the same manner as the first embodiment in other points.
In FIG. 6, the exposure optical system A according to the second embodiment includes a document image reading illumination device A1 ′ instead of the document image reading illumination device A1 according to the first embodiment.

The document image reading illumination device A1 ′ according to the second embodiment has a full-rate carriage FRC ′ whose upper end surface is formed in a planar shape along the lower surface of the document reading surface PG, instead of the full-rate carriage FRC according to the first embodiment. .
The full-rate carriage FRC ′ according to the second embodiment is different from the full-rate carriage FRC according to the first embodiment with the transparent substrate K and the organic EL light source 1 that are opposed to each other with the reflected light transmission port 4 interposed therebetween, and the irradiation light reflector. 3 is omitted, and the bases K ′ and K ′ and the organic EL light sources 1 ′ and 1 ′ of Example 2 are supported so as to be symmetrical in the left-right direction across the reflected light transmission port 4 of Example 2. Yes.

FIG. 7 is an enlarged explanatory view of the organic EL light source and the base of Example 2.
In FIG. 7, the organic EL light sources 1 ′ and 1 ′ according to the second embodiment have light emitting portions 1 a ′ and 1 a ′ instead of the light emitting portion 1 a according to the first embodiment. The light emitting portions 1a ′ and 1a ′ of the second embodiment are curved according to the cosine fourth law as they go from the central portion in the width direction of the light emitting portions 1a ′ and 1a ′ to both ends in the width direction. It is set to be long. Further, the light shielding member 2 of the first embodiment is omitted from the bases K ′ and K ′ of the second embodiment, and is formed along the outer edges of the light emitting sections 1a ′ and 1a ′ and the light emitting section 1a. Transmitting portions 11, 11 that transmit the irradiation light emitted from ', 1a' and light that leaks outward from the outer edges of the light emitting portions 1a ', 1a' outside the transmitting portions 11, 11 are prevented. The light leakage prevention units 12 and 12 are provided.
In addition, the said light leakage prevention parts 12 and 12 of Example 2 can be comprised by what is called a frosted glass by which surface processing of transparent glass was carried out, for example. For example, it is also possible to configure by blackening by black silk printing.

  In the organic EL light sources 1 ′ and 1 ′ of Example 2, the light emitting units 1 a ′ and 1 a ′ irradiate the irradiation light upward. Further, a reflection position AR1 that is a position above the first reflection mirror 6 and an intermediate position between the light emitting portions 1a ′ and 1a ′ is disposed on the original document Gi of the second embodiment.

In Example 2, the first distance L1 as the distance between the light emitting units 1a ′ and 1a ′ is set in advance to 3.0 [mm]. In addition, the second distance L2 and the third distance L3 as distances from the ends of the bases K ′ and K ′ on the reflected light transmitting port 4 side to the light emitting parts 1a ′ and 1a ′ are 0.5 [mm]. It is set in advance. Further, a fourth distance L4 as a distance from the light emitting units 1a ′ and 1a ′ to the lower end surface of the document reading surface PG is preset to 3.0 [mm]. Further, the distance from the upper end surface to the lower end surface of the document reading surface PG, that is, the thickness L5 of the document reading surface PG is preset to 4.0 [mm].
Furthermore, in Example 2, the shortest distance in the central portion, which is the shortest distance in the length direction at the central portion in the width direction of the light emitting portion 1a, is LA ′, and the longest length in the length direction at both widthwise ends of the light emitting portion 1a. The longest distance between both ends, which is the distance, is set in advance to LB ′.

FIG. 8 is an enlarged explanatory view of the optical path of the reflected light by the reflecting mirror and the imaging optical system.
FIG. 9 is a development explanatory view of the optical path of the reflected light in FIG.
Further, in the exposure optical system A of Example 2, a range that is imaged by the solid-state imaging device CCD via the reflecting mirrors 6 to 8 and the imaging lens A3, which is indicated by a one-dot chain line in FIGS. That is, the length L6 in the width direction of the reflection position AR1 of the document Gi is preset to 300 [mm] in accordance with 297 [mm] which is the length of the A3 sheet. An optical path length L7 from the original reading surface PG to the solid-state image sensor CCD is preset to 410 [mm]. Furthermore, a straight line connecting the imaging lens A3 with the outer edge in the width direction of the reflection position AR1 of the document Gi, which is indicated by a one-dot chain line in FIG. 9, and a reflection of the document Gi, which is indicated by a two-dot chain line in FIG. An angle θ formed by the optical axis of the reflected light, which is a straight line connecting the central portion of the position AR1 in the width direction and the imaging lens A3, is preset to 21.5 °.

(Operation of Example 2)
In the image reading apparatus (U1 + PG + A + CCD + IPS) of Example 2 having the above-described configuration, the light emitting portions 1a 'and 1a' of the organic EL light sources 1 'and 1' irradiate the irradiation light upward. For this reason, in the original document Gi, the amount of light applied to the reflection position AR1, which is the image reading position, is maximized. The reflected light corresponding to the image at the reflection position AR1 of the document Gi passes through the reflected light transmission port 4 and is reduced and imaged by the imaging optical system A3 via the reflection mirrors 6-8. Then, the image is picked up by the solid-state image pickup device CCD.

Here, in the image reading apparatus (U1 + PG + A + CCD + IPS) according to the second embodiment, the reflected light from the document Gi is focused by the imaging lens A3, so that the width of the document Gi approaches the both ends in the width direction. As a result, the amount of reflected light to be imaged decreases due to the influence of the cosine fourth law. For example, at both ends in the width direction of the reflection position AR1 of the document Gi, the amount of light after entering the imaging optical system A3 is expressed by the following equation (2) before entering the imaging optical system A3. It turns out that it becomes about 75 [%].
cos ⁴ θ = (cos (21.5 °)) ⁴ ≈0.75 (2)
Therefore, in order for the images at both ends in the width direction to be imaged in a bright state like the image at the center in the width direction that is not affected by the cosine fourth law, the width is expressed by the following equation (3). It can be seen that the amount of light at both ends in the direction needs to be about 1.33 [times] the amount of light at the central portion in the width direction.
0.75 × 1.33≈1 (3)

FIG. 10 is an explanatory diagram of an experimental result of an optical simulation experiment in the image reading apparatus of Example 2, and is a relationship explanatory diagram illustrating a relationship between the distance of the light emitting unit in the length direction of the document and the illuminance at the reflection position of the document. When the illuminance ratio, which is the ratio of the illuminance at each distance of 2 mm or more to the illuminance of 2 mm, when the illuminance at the distance of the light emitting part is 1 on the vertical axis and the illuminance at the distance of the light emitting part is 1 on the vertical axis It is explanatory drawing of a graph.
As shown in FIG. 10, in the image reading apparatus (U1 + PG + A + CCD + IPS) according to the second embodiment, the distance between the light emitting portions 1a 'and 1a' in the length direction of the document Gi, that is, the so-called light emission dimension is x, and x = 2. When the illuminance ratio in the case of [mm] is 1 and the illuminance ratio, which is the ratio of the illuminance at an arbitrary distance x of x ≧ 2 to the illuminance of x = 2 [mm], is y, the distance x and the illuminance ratio For y, the following approximate expression (4) holds. Here, ln (x) is a natural logarithm log _e x of the distance x.
y≈0.8 × ln (x) +0.462 (4)

As a result, for example, when the center shortest distance LA ′ is set to 2.0 [mm], the both end longest distance LB ′ is set to about 3 at which the illuminance ratio y is about 1.33. By setting to 0.0 [mm], the images at both ends in the width direction are picked up in a bright state as with the image at the center in the width direction.
In addition, the image reading apparatus (U1 + PG + A + CCD + IPS) of the second embodiment has the same effects as the image reading apparatus (U1 + PG + A + CCD + IPS) of the first embodiment.

FIG. 11 is an enlarged explanatory diagram of the document image reading illumination device according to the third embodiment, and is an explanatory diagram corresponding to FIG. 6 according to the second embodiment.
Next, the image forming apparatus U according to the third embodiment of the present invention will be described. In the description of the third embodiment, the same reference numerals are given to the components corresponding to the components of the second embodiment, and Detailed description is omitted. The third embodiment is different from the second embodiment in the following points, but is configured in the same manner as the second embodiment in other points.
In FIG. 11, the exposure optical system A according to the third embodiment includes a document image reading illumination device A1 ″ instead of the document image reading illumination device A1 ′ according to the second embodiment.

The document image reading illuminating device A1 ″ according to the third embodiment replaces the full-rate carriage FRC ′ according to the second embodiment, and supports the substrates K ′ and K ′ and the organic EL light sources 1 ′ and 1 ′ internally. It has a carriage FRC ″.
The bases K ′ and K ′ and the organic EL light sources 1 ′ and 1 ′ of Example 3 are supported so as to face each other with the reflection light transmitting port 4 side end inclined downward. In the organic EL light sources 1 ′ and 1 ′ of the third embodiment, the light emitting units 1a ′ and 1a ′ irradiate the irradiation light toward the reflection position AR1.

  In Example 3, the angles formed by the substrates K ′ and K ′ and the organic EL light sources 1 ′ and 1 ′ and the document reading surface PG, that is, the substrates K ′ and K ′ and the organic EL light sources The inclination angle α of 1 ′ and 1 ′ is preset to 20 °. In the third embodiment, the light emitting units 1a ′ and 1a ′ are inclined at the fourth distance L4 as the distance from the light emitting units 1a ′ and 1a ′ to the lower end surface of the document reading surface PG. , And varies depending on the distance x between the light emitting portions 1a ′ and 1a ′. For this reason, the fourth distance L4 of the third embodiment is set in advance to be 3.0 [mm] when x = 3.0 [mm]. That is, the fourth distance L4 is 3.0 [mm] or less when x ≦ 3.0 [mm], and 3.0 [mm] when x ≧ 3.0 [mm]. It is set in advance so as to be above.

(Operation of Example 3)
In the image reading apparatus (U1 + PG + A + CCD + IPS) of Example 3 having the above-described configuration, the light emitting portions 1a ′ and 1a ′ of the organic EL light sources 1 ′ and 1 ′ send the irradiation light to the reflection position AR1 that is the image reading position. Irradiate toward. The reflected light corresponding to the image at the reflection position AR1 of the document Gi passes through the reflected light transmission port 4 and is reduced and imaged by the imaging optical system A3 via the reflection mirrors 6-8. Then, the image is picked up by the solid-state image pickup device CCD.

FIG. 12 is an explanatory diagram of an experimental result of an optical simulation experiment in the image reading apparatus of Example 3, and is a relationship explanatory diagram illustrating a relationship between the distance of the light emitting unit in the length direction of the document and the illuminance at the reflection position of the document. When the illuminance ratio, which is the ratio of the illuminance at each distance of 2 mm or more to the illuminance of 2 mm, when the illuminance at the distance of the light emitting part is 1 on the vertical axis and the illuminance is 2 mm on the vertical axis, It is explanatory drawing of a graph and is a figure corresponding to FIG.
As shown in FIG. 12, in the image reading apparatus (U1 + PG + A + CCD + IPS) of Example 3, the following approximate expression (5) is established for the distance x and the illuminance ratio y.
y≈0.74 × ln (x) +0.52 (5)

As a result, for example, when the center shortest distance LA ′ is set to 2.0 [mm], the both end longest distance LB ′ is set to about 3 at which the illuminance ratio y is about 1.33. By setting to 0.0 [mm], the images at both ends in the width direction are picked up in a bright state as with the image at the center in the width direction.
In addition, the image reading apparatus (U1 + PG + A + CCD + IPS) of the third embodiment has the same effects as the image reading apparatus (U1 + PG + A + CCD + IPS) of the first and second embodiments.

(Example of change)
As mentioned above, although the Example of this invention was explained in full detail, this invention is not limited to the said Example, A various change is performed within the range of the summary of this invention described in the claim. It is possible. Modification examples (H01) to (H06) of the present invention are exemplified below.
(H01) The present invention is not limited to an electrophotographic image forming apparatus, and can also be applied to an inkjet recording image forming apparatus.
(H02) The image recording apparatus (PRy to PRk + Gy to Gk + T1 + T2 + B) of the present invention is not limited to the application to the image forming apparatus U of the first embodiment having the above-described configuration. For example, a printer, a FAX, or a plurality of these It is also possible to apply to a multifunction machine having a function.

(H03) In the first embodiment, the organic EL light source 1 is not limited to the light emitting section 1a, and can be replaced with the light emitting section 1a ′ of the second embodiment, for example.
(H04) In the first embodiment, the light emitting unit 1a of the organic EL light source 1 is supported by the transparent substrate K, but is not limited thereto, and is supported by, for example, the substrate K ′ of the second embodiment. It is also possible.

(H05) In the first embodiment, it is preferable to provide the light shielding member 2 between the transparent substrate K and the original document Gi. However, this may be omitted.
(H06) In the embodiment, the light source that emits the irradiation light irradiated to the entire width direction of the original document Gi is configured by the organic EL light sources 1 and 1 'having the planar light emitting portions 1a and 1a'. However, it is not limited to this, For example, it is also possible to comprise by the inorganic EL light source which has a planar light emission part, or by arranging several LED in a planar form.

FIG. 1 is an overall explanatory view of an image forming apparatus according to Embodiment 1 of the present invention. FIG. 2 is an enlarged explanatory view of a main part of the image forming apparatus according to the first embodiment. FIG. 3 is an enlarged explanatory diagram of the image reading apparatus according to the first embodiment. FIG. 4 is an enlarged explanatory view of the document image reading illumination device according to the first embodiment. FIG. 5 is an enlarged explanatory view of an organic EL light source and a light shielding member of Example 1. FIG. 6 is an enlarged explanatory view of the document image reading illumination device according to the second embodiment and corresponds to FIG. 4 according to the first embodiment. FIG. 7 is an enlarged explanatory view of the organic EL light source and the base of Example 2. FIG. 8 is an enlarged explanatory view of the optical path of reflected light by the reflecting mirror and the imaging optical system. FIG. 9 is a development explanatory view of the optical path of the reflected light in FIG. FIG. 10 is an explanatory diagram of an experimental result of an optical simulation experiment in the image reading apparatus of Example 2, and is a relationship explanatory diagram illustrating a relationship between the distance of the light emitting unit in the length direction of the document and the illuminance at the reflection position of the document. When the illuminance ratio, which is the ratio of the illuminance at each distance of 2 mm or more to the illuminance of 2 mm, when the illuminance at the distance of the light emitting section is 1 on the vertical axis and the illuminance at the distance of the light emitting section is 2 mm on the vertical axis, It is explanatory drawing of a graph. FIG. 11 is an enlarged explanatory diagram of the document image reading illumination device according to the third embodiment, and is an explanatory diagram corresponding to FIG. 6 according to the second embodiment. FIG. 12 is an explanatory diagram of an experimental result of an optical simulation experiment in the image reading apparatus of Example 3, and is a relationship explanatory diagram illustrating a relationship between the distance of the light emitting unit in the length direction of the document and the illuminance at the reflection position of the document. When the illuminance ratio, which is the ratio of the illuminance at each distance of 2 mm or more to the illuminance of 2 mm, when the illuminance at the distance of the light emitting part is 1 on the vertical axis and the illuminance is 2 mm on the vertical axis, It is explanatory drawing of a graph and is a figure corresponding to FIG.

Explanation of symbols

1,1 '... light source,
1a, 1a '... light emitting part,
11 ... transmission part,
12 ... Light leakage prevention part,
2a: Permeation port,
2b: a light shielding part,
2 ... light shielding member,
A1, A1 ′, A1 ″... Document image reading illumination device,
A3: Imaging member,
CCD: Imaging member,
Gi ... manuscript,
K ... Transparent substrate, light leakage prevention member,
K '... the base,
(PRy˜PRk + Gy˜Gk + T1 + T2 + B)... Image recording device,
S ... medium
Sa, Sb ... emission area,
Sa: The light emitting area of the light emitting unit corresponding to the center in the width direction of the document,
Sb: Light emitting area of the light emitting portion corresponding to both ends in the width direction of the document,
(SH + Ra + Rr) ... medium transport device,
U: Image forming apparatus,
(U1 + PG + A + CCD + IPS): Image reading device.

Claims (7)

A light source that emits irradiation light that is applied to the entire width direction of a document on which an image is recorded, the light source having a planar light-emitting portion that emits light, and light emission of the light-emitting portion corresponding to both ends in the width direction of the document The light source having the light emitting portion having an area larger than a light emitting area of the light emitting portion corresponding to a central portion in the width direction of the document;
An illumination apparatus for reading a document image, comprising: In accordance with the cosine fourth power law, the light source set so that the light emitting area increases from the width direction central portion of the light emitting portion toward the both ends in the width direction,
The illumination device for reading a document image according to claim 1, further comprising: The light source having the light emitting portion in which organic electroluminescence elements as light emitting elements that emit light are arranged in a plane,
The illumination device for reading a document image according to claim 1, further comprising: A transparent, planar transparent substrate that supports the light source;
A transparent opening formed along an outer edge of the light emitting portion and transmitting the irradiation light emitted from the light emitting portion; a light shielding portion provided along an outer shape of the transparent substrate; and A light-shielding member disposed between the document and
The illumination device for reading a document image according to any one of claims 1 to 3, further comprising: A planar base for supporting the light source, wherein the base is formed along an outer edge of the light emitting part and transmits the irradiation light emitted from the light emitting part; The base having the light leakage prevention part formed along the outer shape and preventing light leakage from the outer edge of the light emitting part to the outside,
An illumination apparatus for reading a document image according to any one of claims 1 to 4, further comprising: The document image reading illumination device according to any one of claims 1 to 5, wherein the irradiation light is applied to the entire width direction of the document on which the image is recorded.
An imaging member that forms an image of reflected light reflected from the document irradiated with the irradiation light;
An imaging member that images the reflected light imaged by the imaging member;
An image reading apparatus comprising: The image reading apparatus according to claim 6, wherein the image is read by irradiating the irradiation light over the entire width direction of the document on which the image is recorded;
An image recording apparatus for recording the read image on a medium;
A medium conveying device for conveying the medium;
An image forming apparatus comprising: