JP2013102419A - Document illumination unit, document reading device, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize reduction in thickness of a document illumination unit and improvement of illumination efficiency thereof.SOLUTION: In a document illumination unit 20, light radiated from plural light emitting elements 4 arrayed in a x direction is entered and transmitted from an incident surface 3 of a light guide body 1, part thereof is emit from an emission surface 9 facing the incident surface 3 and reflected by a facing reflex board 11 for illuminating an area to be read A on a document platen 10 (beam of light 23 to 25). On a side close to the light emitting element 4 on a horizontal plane 5 of the light guide body 1, a deflection reflection surface 6 is provided, on a side far from the light emitting elements 4 on a horizontal plane 7, a deflection reflection surface 8 is provided, the part of light entered and transmitted in the light guide body 1 is reflected by the deflection reflection surface 8 and caused to transmit the horizontal plane 5 to illuminate the area to be read area A (beam of light 22). The part of light entered and transmitted in the light guide body 1 is reflected by the deflection reflection surface 6, reflected by the deflection reflection surface 8 and caused to transmit the horizontal plane 5 to illuminate the area to be read A (beam of light 21).

Description

  The present invention relates to a document illumination unit, a document reading device, and an image forming apparatus. More specifically, the present invention relates to a document illumination unit used in a reading device such as a digital copying machine or an image scanner, various document reading devices including the document lighting unit, and an image forming apparatus including the document reading device. The forming apparatus can be applied to a copying machine, a facsimile machine, a printer, and a multifunction machine combining some of them.

  In recent years, development of light emitting diodes (hereinafter referred to as LEDs) has been actively conducted. The brightness of the LED element is rapidly increasing, and the cost is decreasing. 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 unit (document illumination device) of an image reading apparatus such as a digital copying machine or an image scanner. For example, the emission spectrum of a white light emitting LED element covers a visible wavelength band, and can be used for a document illumination unit of a color image reading apparatus. For this reason, a wide variety of document illumination units using white LEDs have been proposed.

  Conventionally, a reading illumination system using an LED as a light source employs a configuration method in which a light guide is disposed obliquely with respect to a document table. In this method, the reading light system is configured to be thin in a direction perpendicular to the document table ( It is difficult to save space. On the other hand, when the light guide is arranged horizontally with the document table, the thickness of the apparatus can be reduced, and space can be saved.

  However, when the light guide is arranged horizontally with the document table, it is necessary to emit light from the end of the light guide and guide the light to the reading area on the document table. For example, Patent Document 1 discloses a configuration in which a light emitting plate side surface of the light guide plate 90 is inclined to deflect the optical path toward the document reading position (FIG. 17).

  Further, Patent Document 2 discloses an image reading apparatus aiming at space saving (FIG. 18). Further, Patent Document 3 discloses an image reading apparatus that can form a plurality of light guide paths and can easily align the irradiation position of the irradiation light on the document (FIG. 19).

  On the other hand, in Patent Document 4, light from an LED chip is optically coupled to a thin light guide having a multilayer structure, and light is leaked to the upper portion of the light guide by a fine uneven structure provided in one layer. A lighting device for illuminating the upper part of the lighting device is disclosed.

  However, as in Patent Document 1, if the surface on the light emission end side of the light guide plate is inclined, the light guide becomes thick in order to secure the inclined reflection surface (reference numeral 91 in FIG. 17). There is. Further, in Patent Document 2, two LED units 92 and two light guides 90 are required (two-lamp facing illumination), which increases the cost, and the light guide needs to be slightly thicker on the light exit surface side. was there. Similarly, Patent Document 3 has a problem that it is necessary to project the light exit surface side of the light guide 90 upward, and the light guide 90 becomes thick.

  Thus, conventionally, it has been impossible to reduce the thickness of the document illumination unit (space saving) by sufficiently thinning the light guide. According to Patent Document 4, it is possible to make the light guide thin, but the leaked light irradiates the upper surface of the region where the light guide is arranged, and the light guide is arranged. There was a problem that it was not possible to illuminate a diagonally upward area.

  SUMMARY An advantage of some aspects of the invention is that it provides a document illumination unit, a document reading apparatus, and an image forming apparatus capable of reducing the thickness of the document illumination unit and improving the illumination efficiency.

  In order to achieve such an object, the document illumination unit according to the present invention has a sub-scanning direction as a Z direction, a main scanning direction as an X direction, a direction orthogonal to the X and Z directions as a Y direction, and a length Lx in the X direction, When a length Ly in the Y direction and a length Lz in the Z direction are set, a light guide that satisfies the relationship of Lx> Lz> Ly and the light guide that is disposed across the read area in the Z direction A manuscript illumination unit having a reflex plate and a manuscript table arranged in parallel with the XZ plane of the light guide to form a read area, and radiated from a plurality of light emitting elements arranged in the X direction Is incident and propagated from the incident surface, which is the XY plane of the light guide, into the light guide body, and a part of the light is emitted from the exit surface, which is the XY plane facing the incident surface, to the outside of the light guide, and then the emission surface. Illuminates the area to be read on the platen by reflecting off the counter-reflective plate placed opposite In both of the XZ planes of the light guide, a first light deflecting / reflecting region having an incident angle or a reflection angle larger than that of the other surfaces of the first XZ plane is provided on the side of the first XZ plane close to the document table close to the light emitting element. A second light deflection / reflection region having a smaller incident angle or reflection angle than the other surface of the second XZ surface is provided on the side farther from the light emitting device of the second XZ surface facing the first XZ surface, A part of the light incident on and propagated is reflected by the second light deflecting / reflecting area, then transmitted through the first XZ plane to illuminate the read area on the document table, and from the light emitting element into the light guide. A part of the incident and propagated light is reflected by the first light deflection / reflection area, then reflected by the second light deflection / reflection area, and transmitted through the first XZ surface to make the read area on the document table Illuminate.

  According to the present invention, it is possible to reduce the thickness of the original illumination unit and improve the illumination efficiency.

It is a schematic sectional drawing (YZ surface) of the original illumination unit concerning this embodiment. It is a schematic sectional drawing (XZ surface) of a document illumination unit. It is explanatory drawing of the light beam when not providing a 1st light deflection | deviation reflection area | region. It is explanatory drawing of the light beam when not providing a 3rd light deflection | deviation reflection area | region. It is explanatory drawing of the light beam at the time of providing a 3rd light deflection reflection area. It is explanatory drawing of the light ray at the time of changing the inclination of each reflective surface in a 1st light deflection | deviation reflection area | region. It is explanatory drawing of the light ray at the time of changing the inclination of each reflective surface in the 2nd light deflection reflection area. An example of the partial enlarged view of the 2nd light deflection reflection area is shown. The other example of the partially enlarged view of the 2nd light deflection reflection area is shown. It is explanatory drawing of the light ray in a 1st light deflection | deviation reflection area | region. It is explanatory drawing of a light ray when it has a reflective surface from which an inclination direction differs in a 1st light deflection | deviation reflection area | region. It is explanatory drawing of the light ray in a 2nd light deflection | deviation reflection area | region. It is explanatory drawing of the light ray in case it has a surface from which an inclination direction differs in a 2nd light deflection | deviation reflection area | region. 1 is a schematic cross-sectional view showing an embodiment of a document reading apparatus. It is a schematic sectional drawing which shows other embodiment of a document reader. 1 is a schematic configuration diagram of an image forming apparatus. It is a structural example of the conventional image reading apparatus (patent document 1). It is a structural example of the conventional image reading apparatus (patent document 2). It is a structural example of the conventional image reading apparatus (patent document 3).

  Hereinafter, a configuration according to the present invention will be described in detail based on the embodiment shown in FIGS.

(Original lighting unit)
[First embodiment]
In the document illumination unit according to the present embodiment, the sub-scanning direction is the Z direction, the main scanning direction is the X direction, the direction orthogonal to the X and Z directions is the Y direction, the length Lx in the X direction, and the length Ly in the Y direction. When the length Lz in the Z direction is set, the light guide (light guide 1) satisfying the relationship of Lx>Lz> Ly, and the light guide and the opposing surface arranged with the read area in the Z direction A document illumination unit (contact glass 10) having a reflex plate (opposing reflex plate 11) and a document table (contact glass 10) which is arranged in parallel with the XZ plane of the light guide and on which a read area (document reading area A) is formed. The light is emitted from a plurality of light emitting elements (light emitting elements 4) arranged in the X direction from the incident surface (incident surface 3) which is the XY plane of the light guide into the light guide. Incident and propagated, and part of the exit surface is an XY plane facing the incident surface After exiting from the light guide from the exit surface 9), it is reflected by a counter-reflective plate disposed opposite to the exit surface to illuminate the read area on the document table (light rays 23 to 25), and the light guide A first light deflecting / reflecting region (deflecting / reflecting) having an incident angle or a reflection angle larger than that of the other surface of the first XZ surface on the side close to the light emitting element of the first XZ surface (horizontal plane 5) close to the document table. The second light deflecting / reflecting region (surface 6) is formed on the side farther from the light emitting element of the second XZ surface (horizontal plane 7) opposite to the first XZ surface than the other surface of the second XZ surface has a smaller incident angle or reflection angle. A deflecting / reflecting surface 8) is provided, and a portion of the light incident and propagated from the light emitting element into the light guide is reflected by the second light deflecting / reflecting region and then transmitted through the first XZ surface to be read on the document table. The area was illuminated (light ray 22), and was incident and propagated from the light emitting element into the light guide. Is reflected by the first light deflection / reflection area, then reflected by the second light deflection / reflection area, and transmitted through the first XZ plane to illuminate the read area on the document table (light beam 21). Is.

  FIG. 1 shows a schematic cross-sectional view (YZ plane) of a document illumination unit 20 according to the present embodiment. The document illumination unit 20 is a document reading apparatus that irradiates at least a predetermined illumination width including a document reading area having a predetermined reading width extending long in the main scanning direction of the document, and reads reflected light from the document by an image reading element. It is used.

  FIG. 2 is a schematic sectional view (XZ plane) of the document illumination unit 20 shown in FIG. A plurality of light emitting elements 4 as light sources are arranged regularly spaced in the X direction on the mounting substrate 12 via a holding member (not shown). As the light emitting element 4, for example, a white LED in which a blue light emitting LED element is covered with a phosphor can be used.

  In the example of FIG. 2, the light emitting elements 4 are arranged at an equal pitch in the X direction, but it is also preferable to shorten the arrangement interval (pitch) of the light emitting elements at both ends from the center in the X direction. Even if the original is illuminated uniformly by the illumination system, the illuminance decreases around the screen due to the COS fourth law (cosine fourth law) depending on the angle of view of the imaging optical system. By configuring the light amount distribution to be the reciprocal of the law, it is possible to correct the decrease in the peripheral light amount.

  As shown in FIG. 2, the radiated light from the light emitting element 4 propagates inside the light guide plate 1, and a part of the light beam travels by being totally internally reflected at the side surface, and radiates from the left end (exit surface 9) in the figure. Is done. Further, as will be described later, a part of the light beam is reflected by the deflecting / reflecting region 6 or the deflecting / reflecting regions 6 and 8, and is emitted to the front side (horizontal plane 5) of the drawing.

  As shown in FIG. 1, a light beam emitted from the light emitting surface 4 </ b> A of the light emitting element 4 enters the light guide from the incident surface 3 of the light guide (light guide plate) 1 and propagates while being reflected and refracted. The light guide 1 is held by a holding member (not shown). The light guide 1 is made of acrylic resin, silicon resin, polycarbonate, or the like. Further, the size of the light guide 1 is appropriately set in the X direction according to the document size, for example, about several hundred millimeters, the thickness in the Y direction is, for example, several mm, and the length in the Z direction is For example, it is several millimeters to several tens of millimeters. Further, the distance between the light emitting element 4 and the incident surface 3 is, for example, about 0.5 mm.

  A part of the light beam propagating through the light guide is emitted from the emission surface 9 (light rays 23, 24, 25). In addition, the entrance plane 3, the exit plane 9, and the horizontal planes 5 and 7 (except for the deflection reflection planes 6 and 8 described later) of the light guide 1 are flat planes.

  A counter-reflective plate 11 as a reflecting member is disposed in the traveling direction of the light beams 23, 24, 25 in the center of the radiation angle (Z direction) of the radiated light from the emission surface 9, and reflected by the counter-reflective plate 11 The luminous flux illuminates the original placed on the original surface 2 of the contact glass 10 through the contact glass (original table) 10. In addition, as the opposing reflex board 11, the mirror made from aluminum which has a curvature around a plane or a X direction, an aluminum vapor deposition mirror, etc. can be used.

  In the document illumination unit 20 according to this embodiment, the light guide 1 is a parallel plate, and the horizontal surfaces 5 and 7 are positioned horizontally with the document surface 2. Further, the deflecting reflecting surface 6 is incident on the horizontal surface 5 near the original surface 2 of the light guide 1 and is closer to the light emitting element 4 of the horizontal surface 5 closer to the original surface 2 than the other surfaces of the horizontal surface 5. Is provided.

  The deflecting / reflecting surface 6 is configured by inclining the deflecting / reflecting surface with respect to the document surface 2 as shown in FIG. As a result, the angle formed with the original surface 2 is deflected so as to be smaller than when reflected by the horizontal surface 5. Therefore, the incident angle to the deflecting / reflecting surface 8 to be described next is also increased.

  Further, the deflecting reflecting surface 8 is incident on the horizontal surface 7 that is parallel to the original surface 2 of the light guide 1 and far from the light emitting element 4 of the horizontal surface 7 that is far from the original surface 2, and has a smaller reflection angle than the other surfaces of the horizontal surface 7. Is provided.

  The deflecting / reflecting surface 8 is formed by inclining the deflecting / reflecting surface with respect to the document surface 2 as shown in FIG. As a result, the angle formed with the document surface 2 is deflected so as to be larger than when reflected by the horizontal plane 7. Therefore, the angle at which the reflected light of the deflecting / reflecting surface 8 is incident on the horizontal plane 5 is smaller than when the position of the deflecting / reflecting surface 8 is horizontal to the document surface, that is, when there is no deflecting action.

  At this time, the inclination of the deflecting reflecting surface 8 can be appropriately selected so that the angle of incidence on the horizontal plane 5 is smaller than the total reflection angle. By making it smaller than the total reflection angle, the light beam 21 is transmitted from the horizontal plane 5. The inclination of the deflecting / reflecting surface 8 can be appropriately selected so that the transmitted light (light beam 21) reaches the document reading area A. In this way, the light beam 21 that reaches the incident surface 3 from the light emitting element 4, is reflected by the deflecting / reflecting surface 6 from the incident surface 3, and further reflected by the deflecting / reflecting surface 8 is a light beam 21.

  If the deflecting / reflecting surface 6 is not provided, the light beam corresponding to the light beam 21 is transmitted without being totally reflected by the deflecting / reflecting surface 8 as shown in FIG. 3, and the light beam does not reach the document reading area A. End up.

  In addition to the light beam 21, there is a light beam 22 that reaches the incident surface 3 from the light emitting element 4 and directly enters the deflecting / reflecting surface 8 from the incident surface 3. Here, the inclination of the deflecting / reflecting surface 8 can be appropriately selected so that the incident angle of the light beam 22 reflected by the deflecting / reflecting surface 8 to the horizontal plane 5 becomes smaller than the total reflection angle. By making it smaller than the total reflection angle, the light beam 22 is transmitted from the horizontal surface 5. The inclination of the deflecting / reflecting surface 8 can be appropriately selected so that the transmitted light (light beam 22) reaches the document reading area A.

  According to the configuration of the light guide 1 described above, both the light beam 21 and the light beam 22 can illuminate the document reading area A.

  Further, in addition to the light beams 21 and 22, there is a light beam 23 from the light emitting element 4 to the incident surface 3 and to the output surface 9 facing the incident surface 3. The light beam 23 is reflected by the counter reflex plate 11 disposed so as to face the exit surface 9 and reaches the document reading area A.

  In addition, there is a light beam 24 from the light emitting element 4 to the incident surface 3 and from the incident surface 3 to the horizontal surface 5. The light beam 24 is totally reflected by the horizontal plane 5 and reaches the exit surface 9, and is reflected by the counter reflector 11 from the exit surface 9 and reaches the document reading area A.

  Further, there is a light beam 25 from the light emitting element 4 to the incident surface 3 and from the incident surface 3 to the horizontal surface 7. The light beam 25 is totally reflected by the horizontal plane 7 and reaches the horizontal plane 5, is totally reflected by the horizontal plane 5 and reaches the exit surface 9, is reflected from the exit surface 9 by the counter reflector 11, and reaches the document reading area A.

  Here, as shown in FIG. 4, it is prevented that a part of the light beam reflected from the light emitting element 4 through the incident surface 3 on the horizontal plane 7 and the horizontal plane 5 cannot be received by the counter-reflective plate 11. In order to realize the optical path, as shown in FIG. 5, a deflecting / reflecting surface 13 (third light deflecting / reflecting region) may be added also on the side of the horizontal plane 7 close to the light emitting element 4. As described above, by further adjusting the optical path using a part of the horizontal plane 7 as the deflecting reflection surface 13, the light beam 25 can be reliably guided to the opposing reflex plate 11, and the illumination efficiency can be further improved. Can do.

  Although not shown in the drawings, a cover member is appropriately provided between the light guide 1 and the contact glass 10 in order to shield the direct radiated light beam from the light emitting surface and the light beam leaked from the light guide 1 from moving toward the document surface 2. May be arranged. Further, a diffusion sheet may be disposed between the illumination optical system and the contact glass 10 in order to further reduce chromaticity variation on the document surface 2, to reduce ripples in the illuminance distribution, and to prevent flare.

  According to the document illuminating unit according to the present embodiment described above, the document in which the light beam (light beam 22) deflected and reflected by the deflecting / reflecting surface 8 (second light deflecting / reflecting region) is positioned obliquely above the light guide 1. Since the reading area A can be illuminated, the light guide 1 that is thin in the direction perpendicular to the original surface can be arranged horizontally with respect to the original surface. For this reason, a thin document illumination unit can be configured in the direction perpendicular to the document surface.

  Further, the light beam (light beam 21) deflected and reflected by the deflecting / reflecting surface 6 (first light deflecting / reflecting region) is also deflected and reflected by the deflecting / reflecting surface 8, and the original reading region A located obliquely above the light guide 1 is read. Therefore, the light utilization efficiency can be improved.

  Furthermore, counter illumination is realized by light rays (light rays 23 to 25) which are emitted from the light exit surface 9 of the light guide 1 and reflected by the counter reflex plate 11 and reach the document reading area A, thereby improving light use efficiency. Is possible.

[Second Embodiment]
Hereinafter, other embodiments of the document illumination unit according to the present invention will be described. In addition, the description about the same point as the said embodiment is abbreviate | omitted.

  When the light beam 21 and the light beam 22 are reflected by the deflecting / reflecting surface 8, the inclination angles of the deflecting surface reflection 6 and the deflecting / reflecting surface 8 are appropriately selected so that the incident or reflection angle on the deflecting / reflecting surface 8 satisfies the total reflection condition. Is preferred. As a result, the reflectance can be maximized (transmission loss is eliminated) and the original reading area A can be illuminated, so that the light utilization efficiency can be improved.

[Third embodiment]
Further, as described above, the deflecting / reflecting surface 6 and the deflecting / reflecting surface 8 of the document illumination unit 20 are configured to be inclined with respect to the document surface 2, but the deflecting / reflecting surface 6 is configured as shown in FIG. It is preferably divided into a plurality of deflecting reflecting surfaces in the Z direction. Similarly, the deflecting / reflecting surface 8 is preferably divided into a plurality of deflecting / reflecting surfaces in the Z direction as shown in FIG.

  Thus, by dividing the reflecting surface into a plurality in the Z direction, even if the deflecting reflecting surface having a desired inclination is elongated in the Z direction (giving a width of several millimeters), it does not become thick in the Y direction. The lighting unit 20 can be thinned. Further, as will be described later (fourth embodiment), it is possible to improve illumination efficiency by changing the inclination of each of the divided surfaces.

[Fourth Embodiment]
It is also preferable to change the inclination of each surface of the deflecting reflecting surfaces 6 and 8 in which the reflecting surface described in the third embodiment is divided into a plurality of pieces in the Z direction. This will be described below.

  For example, as shown in FIG. 6, the deflection reflection surface 6 has a larger inclination of the surface (6a) closer to the light emitting element 4 than the side far from the light emitting element (6b), that is, the deflection reflection divided into a plurality of portions in the Z direction. It is preferable to reduce the inclination of the surface on the left side of the surface 6. As a result, the position at which the light beam reflected by the deflecting / reflecting surface 6b enters the deflecting / reflecting surface 8 can be on the right side (the side closer to the light emitting element 4).

  On the other hand, if the angle of the surface of the deflecting / reflecting surface 6 on the side far from the light emitting element 4 (6b) is the same as the angle of the surface on the near side (6a), the light beam reflected from the surface on the far side (6b) enters the deflecting / reflecting surface 8. Since the position to be moved moves to the left side (the side far from the light emitting element 4), it is necessary to lengthen the light guide 1 in the Z direction.

  Thus, the inclination of the deflecting / reflecting surface 6 is adjusted so that the light incident angle on the deflecting / reflecting surface 6a on the side closer to the light emitting element 4 is small and the light incident angle on the deflecting / reflecting surface 6b on the far side is increased. The reflection direction can be appropriately controlled, and light can be efficiently guided to the illumination area obliquely above the light guide. Further, the length of the light guide 1 in the Z direction can be shortened.

  Further, for example, as shown in FIG. 7, the deflecting / reflecting surface 8 has a larger inclination of the surface (8b) farther than the side (8a) closer to the light emitting element 4, that is, divided in the Z direction. It is preferable to increase the inclination of the surface on the left side of the deflecting reflecting surface 8.

  Thereby, it is possible to reflect the light beams on the deflecting reflecting surfaces 8a and 8b in a substantially parallel manner without expanding the reflection direction, and the width of the illumination through the horizontal surface 5 is not widened, and is obliquely above the light guide 1. Light can be efficiently guided to the illumination area. Further, it is possible to illuminate the light condensing by further increasing the angle difference.

  On the other hand, if the angles of the surfaces of the deflecting / reflecting surface 8 near the light emitting element 4 (8a) and the far side (8b) are the same, the light beam reflected by the near deflecting / reflecting surface 8a enters the horizontal surface 5. Even if the angle is further increased and the light passes through the horizontal plane 5, the light beam spreads, resulting in a lower illumination efficiency.

  The above will be described with reference to FIG. A light ray 26 that is incident on the deflection reflection surface 6 at a position farther from the light emitting element 4 in the Z direction than the light ray 21 has an incident angle on the deflection reflection surface 6 larger than that of the light ray 21. Is further away from the light emitting element 4 in the Z direction than the light beam 21, and the incident angle to the deflecting / reflecting surface 8 is slightly larger.

  Therefore, as described above, the light beam 26 reflected by the deflecting reflection surface 8 passes through the horizontal plane 5 and reaches the document reading area A. The inclination is adjusted appropriately.

  Further, if the deflection reflection surface 6 is tilted with respect to the light beam 26 so that the light beam 21 reflected by the deflection reflection surface 6 and the light beam 26 are substantially parallel to each other, Z of the incident positions of the light beam 21 and the light beam 26 on the deflection reflection surface 8 is obtained. Since the distance in the direction does not increase, the document illumination unit 20 can be reduced in size. In this case, since the incident angles are also the same, the inclination of the deflecting reflecting surface 8 with respect to the light beam 21 and the light beam 26 can be made the same.

[Fifth Embodiment]
Moreover, it is preferable that the deflecting reflecting surfaces 6 and 8 are divided into a plurality of parts in the X direction in addition to the Z direction. Hereinafter, the deflection reflection surface 8 will be described as an example.

  FIG. 8 shows a partially enlarged view of the deflecting / reflecting surface 8. The deflection reflection surfaces 81 to 84 are each deflection reflection surface that constitutes a part of the deflection reflection surface 8. Here, the deflection reflection surface 81 and the deflection reflection surface 82 are spaced apart in the X direction. Similarly, the deflection reflection surface 83 and the deflection reflection surface 84 are also spaced apart in the X direction. Here, the distance in the X direction between the deflecting reflecting surface 81 and the deflecting reflecting surface 82 is equal to the distance in the X direction between the deflecting reflecting surface 83 and the deflecting reflecting surface 84.

  By the way, in the case of the configuration of the deflecting / reflecting surface 8 as shown in FIG. 8, when vignetting occurs in a light beam incident on a part of the deflecting / reflecting surface 81 and the deflecting / reflecting surface 82, a part of the light rays enter the document reading area A. Since it will not reach, the area will be dark. Further, since the darkened area is the end of the deflecting / reflecting surface in the Z direction, when the deflecting / reflecting surface 81 and the deflecting / reflecting surface 82 have the same position in the Z direction, they become dark in a state of being pinched in the X direction. An area can arise. As a result, a phenomenon may occur in which the original reading area A becomes darker in a line shape continuously in the main scanning direction.

  Therefore, each of the deflection reflection surfaces 8 of the deflection reflection surface 8 is divided into a plurality of deflection reflection surfaces in the X direction and the Z direction so as to be spaced apart and arranged in parallel in the Z direction. It is preferable to arrange each deflecting reflecting surface so that is in a position shifted in the Z direction. For example, as shown in FIG. 9, the deflection reflection surface 85 is a position between the deflection reflection surface 81 and the deflection reflection surface 82 in the X direction, and the deflection reflection surface 81 and the deflection reflection surface in the Z direction. Although it is arrange | positioned in the position between 83 (it arranges in zigzag form), it should just be shifted | deviated and arrange | positioned at least to a Z direction.

  Here, by providing the deflecting / reflecting surface 85 at a position shifted in the Z direction from the deflecting / reflecting surface 81 and the deflecting / reflecting surface 82, the position where the influence of vignetting is also shifted. In addition, since the angle of the light beam incident on the deflecting / reflecting surface 85 is not uniform, the light beam composed of the deflected and reflected light group spreads to illuminate the document reading area A. At this time, the deflecting / reflecting surface 81 and the deflecting / reflecting surface are illuminated. Illumination is performed by superimposing on the darkened area of 82. Therefore, the light flux from the deflection reflection surface 85 is illuminated in the region where the illuminance is lowered due to the light beam generated on part of the surfaces of the deflection reflection surface 81 and the deflection reflection surface 82, and the reduced illuminance is compensated.

  In this way, the original reading area A is illuminated by the light beams deflected and reflected by the deflecting reflection surfaces 81 and 82, and the light beams deflected and reflected by the deflecting reflection surface 85 are superimposed and illuminated. Even when vignetting occurs in a part of the light flux incident on the light beam and a pattern in which the illuminance decreases in a line shape in the main scanning direction is generated, the illuminance reduction is improved and the line-shaped dark area continuously in the main scanning direction. Can be prevented.

  In addition, as described in the fourth embodiment, each deflecting / reflecting surface preferably has a larger inclination of the surface (8b) farther than the side (8a) closer to the light emitting element 4 (FIG. 7). That is, the inclination of the deflection reflection surface 81 and the deflection reflection surface 82 with respect to the horizontal plane 7 and the inclination of the deflection reflection surface 83 and the deflection reflection surface 84 with respect to the horizontal plane 7 are equal, and the inclination of the deflection reflection surface 81 with respect to the horizontal plane 7 is The inclination of the deflecting / reflecting surface 83 with respect to the horizontal plane 7 is larger, the inclination of the deflecting / reflecting surface 85 with respect to the horizontal plane 7 is smaller than the inclination of the deflecting / reflecting surface 81 with respect to the horizontal plane 7, and the inclination of the deflecting / reflecting surface 85 with respect to the horizontal plane 7 is It is preferable that the inclination of the deflecting / reflecting surface 83 with respect to the horizontal plane 7 is larger.

  8 and 9 show a part of the deflection reflection surface 8, and each deflection reflection surface is arranged in a staggered manner over the entire deflection reflection surface 8 in the X and Z directions. . In the present embodiment, the deflecting / reflecting surface 8 has been described, but the same applies to the deflecting / reflecting surface 6 (the state in which FIGS. 8 and 9 are inverted up and down).

[Sixth Embodiment]
Further, the deflecting reflecting surfaces 6 and 8 divided into a plurality in the Z direction have inclined surfaces in a direction different from the deflecting reflecting surfaces 6 and 8 between the deflecting reflecting surfaces 6 and 8 in the Z direction. It is also preferable.

  As shown in FIG. 10, depending on the position where the light beam L is incident on the deflecting / reflecting surface 6c constituting the deflecting / reflecting surface 6, the deflected / reflected light beam L may be vignetted by the adjacent reflecting surface 6d. Therefore, as shown in FIG. 11, the reflection surface 6d between the plurality of deflection reflection surfaces 6c in the Z direction is inclined in a direction different from the deflection reflection surface 6c in the Z direction (that is, the reverse direction). The light beam L can be prevented from being vignetted on the reflecting surface 6d. Thereby, since the vignetting light can be used as illumination light, the light use efficiency can be further improved.

  The same applies to the deflecting / reflecting surface 8. That is, as shown in FIG. 12, a dead zone D in which the light beam L does not enter is generated in a part of the deflection reflection surface 8 c constituting the deflection reflection surface 8. Therefore, as shown in FIG. 13, by making the surface 8d between the plurality of deflection reflection surfaces 8c in the Z direction an inclined surface in a direction different from the deflection reflection surface 8c in the Z direction (that is, the reverse direction), It is possible to prevent the dead zone D from occurring on the deflecting reflecting surface 8c. Thereby, it becomes possible to further improve the light utilization efficiency.

[Seventh Embodiment]
In addition, it is preferable that the light guide 1 is disposed on the side closer to the light emitting element 4 in the Z direction than the halation line, and the opposing reflex plate 11 is disposed on the side farther from the light emitting element 4 in the Z direction than the halation line.

  If the position of the exit surface 9 of the light guide 1 is on the inner side of the halation line, halation occurs when the document surface is inclined. For example, when the document surface is tilted by 10 degrees, the angle of light rays that are regularly reflected from the document is 20 degrees.

  In FIG. 1, a line of light that is regularly reflected at 20 degrees from the document reading area A is shown as a halation line 15. For this reason, the position of the exit surface 9 of the light guide 1 is preferably arranged so as to be farther from the optical axis 14 in the Z direction than the halation line 15.

  Thereby, since the reflected light of 20 degrees reflected from the reading area A does not hit the light guide 1, halation does not occur. Specifically, when a part of the document surface 2 is floating, it is reflected by the document surface 2 and returned to the light guide 1 side, reflected by the light guide 1 and returned to the document surface 2 again. It is possible to avoid the halation that occurs when the light is reflected again at 2 and received by the image sensor via the reading optical system.

  Similarly, if the counter reflex plate 11 is located inside the halation line 16, halation occurs when the document surface 2 is inclined. The inclination of the halation line 16 is indicated by −20 degrees.

  For this reason, the position of the opposing reflex plate 11 is on the side farther from the light emitting element 4 in the Z direction than the light guide plate 1 across the optical axis 14, and in a direction farther from the optical axis 14 in the Z direction than the halation line 16. It is preferable to arrange the opposing reflex plate 11.

  As a result, the reflected light of 20 degrees reflected from the reading area A does not hit the counter-reflective plate 11, and therefore halation does not occur. Specifically, when a part of the document surface 2 is floating, it is reflected by the document surface 2 and returned to the counter reflex plate 11, is reflected by the counter reflex plate 11 and returns to the document surface 2 again, and the document surface 2 In this case, it is possible to avoid halation caused by reflection again and receiving light on the image sensor via the reading optical system.

  The positions and angles of the halation lines 15 and 16 may be set as appropriate according to the inclination angle of the original, the width of the original reading area A in the Z direction, and the like.

(Original reading device)
By using the document reading apparatus provided with the document illumination unit 20 described above, the illumination device section can be made much thinner than the conventional one, and the reading optical system section does not become thick thereby, so the document reading apparatus. However, it can be made thinner than before.

  FIG. 14 is a schematic sectional view showing an embodiment of a document reading apparatus according to the present invention. The document reading device 30 includes an image sensor 31, a document table (contact glass) 10 on which a document 35 is placed, a document illumination unit 20, and reflected light from the document 35 illuminated in a line by the document illumination unit 20. An imaging optical system that forms an image on the image sensor 31. The illumination optical system of the document illumination unit 20 is shown as 20A, and the counter illumination optical system is shown as 20B.

  As the image sensor 31, for example, a CCD can be used. In the CCD 31, an optical signal of document surface information is photoelectrically converted into an electric signal, and the document surface 2 of the document 35 can be read.

  The imaging optical system includes a first reflecting mirror 33A, a second reflecting mirror 34B, a third reflecting mirror 34C, a first traveling body 33, a second traveling body 34, and an imaging lens 32. And have. The first traveling body 33 travels while holding the document illumination device 20 and the first reflecting mirror 33A. The second traveling body 34 travels while holding the second reflecting mirror 34B and the third reflecting mirror 34C. At this time, a speed ratio V1: V2 between the traveling speed V1 of the first traveling body 33 and the traveling speed V2 of the second traveling body 34 is 2: 1.

  As shown in FIG. 14, when the displacement width in the Z direction of the first traveling body 33 is z, the optical path length, which is the distance between the document reading area 5 and the CCD 31, varies by z. On the other hand, as shown in FIG. 14, when the displacement width of the second traveling body 34 in the Z direction is similarly z, the optical path length, which is the distance between the document reading area A and the CCD 31, varies by 2 × z. Therefore, when the speed ratio V1: V2 is 2: 1, reading scanning can be performed while keeping the optical path length from the document reading area A to the CCD 31, in other words, the conjugate length of the imaging optical system constant.

  According to the document reading device 30 of the present embodiment, since the document illumination unit 20 is thinned, the document reading device 30 can also be configured to be thin and compact. In addition, the installation error of the optical elements such as the reflection surfaces, the reflection mirrors, and the imaging lens 32 and the dynamic fluctuations associated with the scanning drive are allowed, and the stability of the light reception signal on the light reception surface of the image sensor 31 is improved. An excellent device can be realized. Alternatively, the tolerances of these optical elements can be relaxed. That is, it is resistant to fluctuations in the received light signal on the light receiving surface of the image sensor 31 due to static positional deviation in the document reading device 30 and dynamic position fluctuation.

  FIG. 15 is a schematic cross-sectional view showing another embodiment of the document reading apparatus according to the present invention. In addition, the description about the same point as the said embodiment is abbreviate | omitted.

  The imaging optical system in the document reading apparatus 30 shown in FIG. 15 includes a reflection mirror 37D and an imaging lens 32. The imaging element 31, the document illumination unit 20, the reflection mirror 37D, and the imaging lens 32 are provided. Is run as a unit. The information on the document 35 can be read by driving the single traveling body 37 in the sub-scanning direction.

  According to the document reading device 30 of the present embodiment, since the document illumination unit 20 is thinned, the document reading device 30 can also be configured to be thin and compact. Further, since it is not necessary to separately drive the reflection mirror 37D during scanning, it is possible to simplify the drive mechanism device and to reduce the size and weight of the entire document reading device. Further, even if vibration or the like occurs when the traveling body is driven to scan, relative positional fluctuations of the document illumination device 30, the reflection mirror 37D, the imaging lens 32, and the imaging element 31 are compared with the example shown in FIG. As a result, the signal noise associated with the read scanning drive is reduced, and the optical signal characteristics received on the light receiving surface of the image sensor 31 are stabilized.

(Image forming device)
By using the image forming apparatus including the document illumination unit 20 or the document reading device 30 described above, the document reading unit can be made thinner than the conventional one, and accordingly, other parts of the image forming apparatus Since it is not necessary to increase the thickness, the image forming apparatus can be made thinner than before.

  FIG. 16 is a schematic front view showing the internal structure of the full-color copying machine 100. An image forming unit 103 for forming a color image is provided at the center of the apparatus main body 102 of the copying machine 100. The image forming unit 103 includes four drum-shaped photosensitive members 104 that are spaced apart at equal intervals and arranged in parallel in the horizontal direction, a charging roller 105 that uniformly charges the outer peripheral surface of the photosensitive member 104, and a charging roller 105. An exposure device 106 that forms an electrostatic latent image by exposing the outer peripheral surface of each of the photosensitive members 104 charged in accordance with the image data, and supplying the toner to the electrostatic latent image to convert the electrostatic latent image into a toner image A developing device 107 that visualizes the toner image, an intermediate transfer belt 108 onto which the toner image on the photoconductor 104 is sequentially transferred, and a cleaning that removes toner remaining on the photoconductor 104 after the transfer of the toner image onto the intermediate transfer belt 108. The apparatus 109 includes a transfer roller 110 that transfers the toner image transferred onto the intermediate transfer belt 108 to the recording medium S, and the like. Note that toner images of different colors (Y: yellow, M: magenta, C: cyan, K: black) are formed on the four photoconductors 104, and the toner images of these colors are formed on the intermediate transfer belt 108. By being transferred, a color toner image is formed on the intermediate transfer belt 108, and this color toner image is transferred to the recording medium S.

  On the upper part of the apparatus main body 102, an ADF 111 that automatically feeds a document that is an object to be illuminated by the document illumination unit 20, a contact glass 10 on which the document is placed, and a document or contact glass 10 that is automatically fed by the ADF 11 A document reading device 30 that reads the placed document is disposed.

  The document reading device 30 includes first and second traveling bodies 114 and 115 capable of traveling at a speed of 2: 1 in parallel with the contact glass 10, a lens 116, a CCD 117 serving as a document reading unit, and the like. The first traveling body 114 includes a document illumination unit 20 for illuminating a document surface of a document placed on the contact glass 10 or a document conveyed by the ADF 111, and a reading optical axis reflected by the document surface. And a first mirror 119 that reflects the reading light that travels along. A second mirror 120 and a third mirror 121 that further reflect the light reflected by the first mirror 119 are mounted on the second traveling body 115. A lens 116 and a CCD 117 are disposed in front of the reading light sequentially reflected by the first to third mirrors 119, 120, and 121 in the traveling direction. The document reading device 30 can also be operated independently as a scanner device.

  A plurality of, for example, four-stage paper cassettes 124 for storing the recording medium S are provided at the lower part of the apparatus main body 102. The recording media S stored in these paper cassettes 124 are separated and fed one by one by the pick-up roller 125 and the feed roller 126, and the separated and fed recording media S are conveyed by the paper provided in the apparatus main body 102. It is conveyed along the path 127. On the sheet conveyance path 127, a registration roller 128, a transfer roller 110, a fixing device 129, a paper discharge roller 130, and the like are arranged.

  In such a configuration, laser light corresponding to the image data of each color (yellow Y, magenta M, cyan C, black K) is emitted from the semiconductor laser of the exposure device 106 in accordance with the reading result of the document reading device 30, An electrostatic latent image is formed by exposing the outer peripheral surface of each photoconductor 104 to which the laser light is uniformly charged by the charging roller 105. Each color toner is supplied from each developing device 107 to the electrostatic latent image, whereby a toner image of each color is formed. The toner image on each photoconductor 104 is sequentially transferred onto an intermediate transfer belt 108 that moves in synchronization with the photoconductor 104, and a color toner image is formed on the intermediate transfer belt 108.

  On the other hand, when the image forming operation in the image forming unit 103 is started, the recording medium S starts to be separated and fed from the sheet cassette 124 and is separated and fed on the sheet conveyance path 127. Is transferred to a transfer position between the intermediate transfer belt 108 and the transfer roller 110 by a registration roller 128 that is driven to rotate intermittently.

  Next, the registration roller 128 is rotated and the recording medium S is fed between the intermediate transfer belt 108 and the transfer roller 110, whereby the color toner image on the intermediate transfer belt 8 is transferred onto the recording medium S. The color toner image transferred onto the recording medium S is fixed to the recording medium S while the recording medium S passes through the fixing device 129, and the recording medium S on which the color toner image is fixed is discharged by the paper discharge roller 130. The paper is discharged onto the tray 131.

  The above-described embodiment is a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 Light guide 2 Original surface 3 Incident surface 4 Light emitting element 4A Light emitting surface 5 Horizontal surface (1st XZ surface)
6 Deflection reflection surface (first light deflection reflection area)
6a Deflection reflecting surface (side closer to the light emitting element)
6b Deflection reflecting surface (the side far from the light emitting element)
6c Deflection reflection surface 6d Reflection surface 7 with different inclinations Horizontal surface (second XZ surface)
8 Deflection / Reflection Surface (Second Light Deflection / Reflection Area)
8a Deflection / reflection surface (side closer to the light emitting element)
8b Deflection / reflection surface (the side far from the light emitting element)
8c deflection reflection surface 8d surfaces 81 to 85 each deflection reflection surface 9 exit surface 10 contact glass (original table)
11 Counter-reflective plate 12 Mounting substrate 13 Deflection reflection surface (third light deflection reflection region)
14 optical axis 15 halation line 16 halation line 20 original illumination unit 21 light 22 light 23 light 24 light 25 light 26 light 30 original reading device 100 image forming apparatus A original reading area D dead zone L light

JP 2010-252340 A JP 2010-16496 A JP 2010-191397 A Special table 2007-535790 gazette

Claims (11)

The sub-scanning direction is the Z direction, the main scanning direction is the X direction, and the direction orthogonal to the X and Z directions is the Y direction.
When the length Lx in the X direction, the length Ly in the Y direction, and the length Lz in the Z direction, a light guide that satisfies the relationship of Lx>Lz> Ly,
An opposing reflex plate disposed across the read area in the Z direction with the light guide;
A document illumination unit having a document table disposed in parallel with the XZ plane of the light guide and on which the read area is formed,
Light emitted from a plurality of light emitting elements arranged in the X direction is caused to enter and propagate from the incident surface, which is the XY plane of the light guide, into the light guide, and a part of the light is opposed to the incident surface. After exiting the light guide from the exit surface that is a surface and illuminating the read area on the document table by being reflected by the opposing reflex plate disposed facing the exit surface,
A first light deflecting / reflecting region having an incident angle or a reflection angle larger than that of the other surface of the first XZ surface on the side of the first XZ surface close to the document table near the light emitting element in the XZ surface of the light guide. The
A second light deflection / reflection region having a smaller incident angle or reflection angle than the other surface of the second XZ surface is provided on a side farther from the light emitting element of the second XZ surface facing the first XZ surface;
Part of the light incident and propagated from the light emitting element into the light guide is reflected by the second light deflecting / reflecting area, and then transmitted through the first XZ surface, thereby allowing the read area on the document table to pass through. Illuminate and
In addition, a part of the light incident and propagated from the light emitting element into the light guide is reflected by the first light deflecting / reflecting region and then reflected by the second light deflecting / reflecting region. A document illumination unit that illuminates the read area on the document table through the 1XZ plane. The inclinations of the deflection reflection surfaces of the first light deflection reflection area and the second light deflection reflection area are:
A light beam reflected from the first light deflection reflection region and reaching the second light deflection reflection region and a light beam from the light emitting element to the second light deflection reflection region both satisfy an internal total reflection condition. The document illumination unit according to claim 1.   3. The deflection reflection surface of the first light deflection reflection region and / or the second light deflection reflection region is divided into a plurality of deflection reflection surfaces in the Z direction. Document lighting unit.   The deflecting / reflecting surface of the first light deflecting / reflecting area is divided into a plurality of deflecting / reflecting surfaces in the X direction and the Z direction and spaced apart, and each row of the deflecting / reflecting surfaces arranged in parallel in the Z direction is Z. 4. The document illumination unit according to claim 1, wherein the document illumination unit is in a position shifted in the direction.   The deflecting / reflecting surface of the second light deflecting / reflecting area is divided into a plurality of deflecting / reflecting surfaces in the X direction and the Z direction, and each of the deflection reflecting surfaces arranged in parallel in the Z direction is Z. 5. The document illumination unit according to claim 1, wherein the document illumination unit is in a position shifted in the direction.   5. The document illumination unit according to claim 3, wherein a reflection surface of the first light deflection reflection region has a larger inclination of a surface closer to a side farther than the light emitting element.   6. The document illumination unit according to claim 3, wherein a reflection surface of the second light deflection reflection region has a smaller inclination of a surface closer to a side farther than the light emitting element.   8. The document illumination unit according to claim 3, wherein an inclined surface having a direction different from the plurality of deflection reflection surfaces is provided between the plurality of deflection reflection surfaces in the Z direction. 9.   The light guide is disposed on the side closer to the light emitting element in the Z direction than the halation line and / or the counter reflector is disposed on the side farther from the light emitting element in the Z direction than the halation line. The document illumination unit according to claim 1.   An original reading apparatus comprising the original illumination unit according to claim 1.   An image forming apparatus comprising the document illumination unit according to claim 1 or the document reading device according to claim 10.

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