JP5328551B2 - Illumination apparatus, image reading apparatus, image forming apparatus, and substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lighting system irradiating light from a plurality of light emitting elements arrayed on a substrate toward a light irradiation surface of an object to be irradiated, utilizing light emitting elements generally available on the market over a wide range of brightness ranks without drastically changing a structure of the lighting system, thereby allowing use of light emitting elements with reduced cost, and to provide an image reading device, an image forming device and a substrate. <P>SOLUTION: In a lighting system 210, light from a plurality of light emitting elements 212 arrayed on a substrate 213 is irradiated toward a light irradiation surface Gd of an irradiation object G. The plurality of light emitting elements 212 can be arranged so that at least either one of an optical axis distance H and a light irradiation position in a sub-scanning direction Y can be set based on a plurality of brightness ranks R1, ..., Rn, while the light emitting elements 212 are ranked in the brightness ranks R1, ..., Rn set in advance corresponding to the brightness of light emitted. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to an illumination device, an image reading device, an image forming apparatus, and a substrate that irradiate light from a plurality of light emitting elements arranged on a substrate toward a light irradiation surface of an irradiated object.

  As a conventional illumination device employed in an image reading apparatus provided in an image forming apparatus such as a copying machine, a facsimile machine, and a digital multifunction peripheral, or an image reading apparatus connected to a computer via a communication means such as a network, for example, There is one in which a plurality of light emitting elements such as a light emitting diode (LED) are arranged on a substrate.

  Such an illuminating device is employed in, for example, an image reading apparatus that scans an image of a document placed on a document placing table in a main scanning direction and a sub-scanning direction using an irradiated body as a document. In such an illuminating device, the plurality of light emitting elements are arranged in a line along the main scanning direction.

  FIG. 28 is a diagram showing a conventional illumination device A1 in which a plurality of light emitting elements A3,... Are arranged on a substrate A2. FIG. 28A shows a plan view of the illumination device A1, and FIG. 28B shows a side view of the illumination device A1 viewed from the main scanning direction X. In FIG. 28A, the document placing table 201 and the document G are also illustrated. 29 is a diagram for explaining uneven illuminance on the light irradiation surface Gd of the document G by the light emitting elements A3,... Shown in FIG. 29A shows a graph of illuminance with respect to the distance in the main scanning direction X on the light irradiation surface Gd of the original G corresponding to the arrangement configuration of the light emitting elements A3,... FIG. The arrangement configuration of the elements A3,.

  As shown in FIG. 28, an illuminating device A1 in which a plurality of light emitting elements A3,... Are arranged in a line on a substrate A2 is used to emit light L from each light emitting element A1,. Irradiation is directed toward the light irradiation surface Gd.

  By the way, in general light emitting elements such as LEDs that are commercially available, the luminance of emitted light is not always supplied at the same level, and has a certain luminance range.

  FIG. 30 is a graph illustrating an example of a luminance distribution of a light emitting element such as an LED. As shown in FIG. 30, since a light emitting element such as an LED has a certain luminance range, a specific luminance rank (signs R1,..., Rn (n is an integer of 2 or more in FIG. 30) depends on the luminance level. ))) Is generally ranked. By doing so, the user can understand how much luminance the light emitting element to be used has.

  As an illuminating device in which a plurality of light emitting elements are arranged on a substrate, in Patent Document 1 below, light emitting elements with high luminous intensity and light emitting elements with low luminous intensity are arranged so that the illuminance distribution is uniform, or the luminous intensity level is set. There has been proposed an illuminating device in which light emitting elements are arranged at a light emitting element pitch in a corresponding arrangement direction or the luminous intensity of the light emitting elements themselves is adjusted.

JP 2008-180842 A

  As shown in FIG. 30, light emitting elements such as LEDs used in such conventional lighting devices include light emitting elements that tend to be higher than the average brightness, and light emitting elements that tend to be lower than the average brightness. There is also. For this reason, when a light emitting element having a brightness rank far from the average brightness is used in the lighting device, there are the following disadvantages.

  For example, if the brightness rank is too low, the degree of freedom in design is reduced. Therefore, in order to secure a necessary minimum amount of light, a light emitting element having a certain brightness rank (bright) may be limited and used. .

  Then, among the light emitting elements of all luminance ranks that are commercially available, it is not possible to use (purchase) a light emitting element with a low luminance rank (for example, a relatively inexpensive light emitting element such as rank R1 indicated by the hatched portion in FIG. 30). Therefore, it becomes disadvantageous in price.

  Therefore, in order to use the light emitting element over a wide range of luminance ranks, for example, when using a light emitting element with a low luminance rank (darker), the substrate on which the light emitting element is mounted may be placed close to the document. Therefore, a significant change in the configuration of the lighting device is caused for each luminance rank. On the other hand, the light emitting element having a lower luminance rank may be located at that position. However, when a light emitting element having a higher luminance rank (brighter) is used, uneven illuminance (see FIG. 29) on the light irradiation surface of the document is conspicuous at that position.

  In this regard, as in the illumination device described in Patent Document 1, light emitting elements with high luminous intensity and light emitting elements with low luminous intensity are arranged so that the illuminance distribution is uniform, or light emission in the arrangement direction according to the luminous intensity level. Even if the light emitting elements are arranged at the element pitch, the illuminance on the light irradiation surface of the original does not change (for example, improve) as a whole, so use the ranked light emitting elements over a wide range of luminance ranks. I can't.

  Further, when the luminous intensity of the light emitting element itself is adjusted as in the lighting device described in Patent Document 1, for example, when a light emitting element having a lower luminance rank is used, the current value flowing through the light emitting element is increased. However, in this case, there is a limit in compensating for the shortage of light, and forcibly compensating for the shortage of light causes a reduction in the lifetime of the light emitting element.

  Therefore, the present invention is an illumination device that irradiates light from a plurality of light emitting elements arranged on a substrate toward a light irradiation surface of an object to be irradiated, and greatly changes the configuration of the illumination device. In general, a commercially available light-emitting element can be used over a wide range of luminance ranks, and thereby an illumination device that can use a light-emitting element that achieves cost reduction, an image reading apparatus, an image forming apparatus, and a substrate having the same The purpose is to provide.

In order to solve the above-described problems, the present invention provides the following lighting device according to the first aspect and the second aspect.
(1) A lighting device that irradiates light from a plurality of light emitting elements arranged on the lighting device substrate of the first aspect toward a light irradiation surface of an irradiated object, wherein the plurality of light emitting elements emit light. A plurality of brightness ranks set in advance with respect to the brightness of the light to be emitted are ranked, and based on the brightness rank, the optical axis distance to the irradiated object and the arrangement direction of the light emitting elements intersect. The light emitting element can be arranged so that at least one of the light irradiation positions in the direction can be set, and the substrate can be arranged based on the luminance rank. The substrate is formed with a plurality of arrangement pattern rows arranged in the arrangement direction for arranging the light emitting elements along the arrangement direction of the light emitting elements, along a direction intersecting the arrangement direction. The plurality of Among location pattern array, the illumination device characterized by light-emitting element of the luminance ranked set arrangement pattern string based on the luminance rank are disposed.
(2) Lighting device of the second aspect
An illumination device that irradiates light from a plurality of light emitting elements arranged on a substrate toward a light irradiation surface of an irradiated object, wherein the plurality of light emitting elements are set in advance with respect to luminance of emitted light. A plurality of brightness ranks, and based on the brightness rank, at least one of an optical axis distance to the irradiated body and a light irradiation position in a direction intersecting with an arrangement direction of the light emitting elements. The light emitting elements can be arranged so that one of them can be set, and the substrate is configured to be able to arrange the light emitting elements based on the luminance rank, and a plurality of types of substrates having different thicknesses from each other. Among these, the light emitting element of the said brightness rank is arrange | positioned on the board | substrate of the thickness set based on the said brightness rank, The illuminating device characterized by the above-mentioned.

The present invention also provides an image reading apparatus comprising the illumination device according to the first aspect or the second aspect of the present invention.

  The present invention also provides an image forming apparatus comprising the image reading apparatus according to the present invention.

In the illumination device, the image reading device, and the image forming device according to the first aspect or the second aspect of the present invention, based on the luminance rank, the optical axis distance to the irradiated body and the arrangement direction of the light emitting elements. Since the light emitting element can be arranged so that at least one of the light irradiation positions in the intersecting direction can be set, the light emitting element can be arranged without significantly changing the configuration of the illumination device. The optical axis distance to the irradiated object and / or the light irradiation position can be easily set only by disposing on the substrate. For example, in the case of using a light emitting element having a lower luminance rank, the light emitting element can be easily brought close to the irradiated body to the substrate to improve the illuminance on the light irradiation surface of the irradiated body as a whole. Can be arranged. In addition, when using a light emitting element having a high luminance rank, the light emitting element can be easily moved away from the irradiated body in order to make the illuminance unevenness (bright spot) on the light irradiated surface of the irradiated body inconspicuous. It can be placed on the substrate. Thereby, a commercially available light emitting element can be used over a wide range of luminance ranks.

The substrate is configured such that the light emitting element can be arranged based on the luminance rank, and the optical axis distance and / or the light irradiation position can be changed based on the luminance rank as the substrate. Can be used. In this way, by using the substrate that can change the optical axis distance and / or the light irradiation position based on the luminance rank, the optical axis distance and / or the light irradiation position can be easily set by the substrate. Can do.

In the illumination device according to the first aspect of the present invention , the substrate includes a plurality of arrangement pattern rows in which arrangement patterns for arranging the light emitting elements are respectively arranged along the arrangement direction of the light emitting elements. The light emitting elements having the brightness rank are arranged in a placement pattern row set based on the brightness rank among the plurality of placement pattern rows. Therefore, the light emitting elements can be arranged in any of the plurality of arrangement pattern rows according to the luminance rank. Thereby, the optical axis distance and / or the light irradiation position can be easily set with a simple configuration.

Moreover, this invention is a board | substrate with which the illuminating device of the 1st aspect which concerns on the said this invention is provided, Comprising: The arrangement | positioning pattern for arrange | positioning the said light emitting element is each arranged in multiple along the row direction of the said light emitting element The substrate is characterized in that the arrangement pattern row is formed along a direction intersecting (for example, orthogonal to) the row direction.

In the lighting device of the second embodiment according to the present invention, by different among a plurality of types of the substrate thickness, the light-emitting element of the luminance rank substrate of the set thickness on the basis of the luminance rank are disposed to each other, wherein The light emitting element can be arranged on any of the plurality of types of substrates according to a luminance rank. Thereby, the optical axis distance and / or the light irradiation position can be easily set with a simple configuration .

In the illumination device according to the first aspect and the second aspect of the present invention , among the plurality of light emitting elements, the light emitting element having the lower brightness rank is closer to the irradiated body than the light emitting element having the higher brightness rank. The mode arrange | positioned can be illustrated.

  In this specific matter, the illuminance on the light-irradiated surface of the irradiated object can be improved for the light emitting element with the lower brightness rank, and the irradiated object for the light emitting element with the higher brightness rank. Irradiance unevenness in the arrangement direction of the light emitting elements on the light irradiation surface of the body can be made inconspicuous.

In the illumination device according to the first aspect and the second aspect of the present invention , the plurality of light emitting elements are arranged along a slit for allowing reflected light from the irradiated object to pass therethrough, and the slit is used as a reference. Thus, a first light emitting element row composed of a plurality of first light emitting elements arranged on one side in the short direction of the slit, and a plurality of second light lines arranged on the other side in the short direction of the slit. You may be comprised with the 2nd light emitting element row | line | column which consists of a light emitting element.

  In this specific matter, since the first light emitting element row and the second light emitting element row are arranged on both sides in the short direction of the slit, as the light emitting element, for example, in one light emitting element row, a luminance rank is set. Even if a lower light emitting element is used, the lower luminance of the light emitting element can be compensated for by the light emitting element in the other light emitting element array facing the light emitting element. This makes it possible to use a commercially available light emitting element over a wider range of luminance ranks.

The illuminating device according to the first and second aspects of the present invention includes, for example, a document placing table on which the document is placed, and the image of the document placed on the document placing table. It may be provided in an image reading apparatus having a document fixing configuration that scans and reads in the main scanning direction and the sub-scanning direction, or includes an original conveying apparatus that automatically conveys an original, and an image of the original conveyed by the original conveying apparatus. It may be provided in an image reading apparatus having a document movement configuration that scans and reads in the main scanning direction and the sub-scanning direction. Alternatively, it may be provided in an image reading apparatus combining these.

When the illumination device of the first aspect and the second aspect according to the present invention is provided in an image reading apparatus having the original fixing configuration and an image reading apparatus combining the original moving configuration and the original fixing configuration, the slit is the main Arranged along the scanning direction, the illumination device is a scanning device that is fixedly arranged at a fixed position in the sub-scanning direction with respect to the document conveyed by the document conveying device when reading an image of the document. be able to.

When the illumination device according to the first aspect and the second aspect according to the present invention is provided in an image reading device having the document moving configuration and an image reading device combining the document moving configuration and the document fixing configuration, the slit is the main The illumination device is arranged along the scanning direction, and the illumination device is a scanning device that moves to one side in the sub-scanning direction with respect to the document placed on the document placement table when reading the image of the document. be able to.

By the way, when the illumination device of the first aspect and the second aspect according to the present invention is provided in an image reading apparatus having the document moving configuration and an image reading apparatus combining the document moving configuration and the document fixing configuration, When the light emitting element array and the second light emitting element array are arranged on both sides in the short direction of the slit, the sub-scan of the document is read when reading the image of the document placed on the document placing table. A shadow tends to appear at the upstream end in the direction toward one side of the direction. The occurrence of this shadow becomes remarkable particularly when the original is thick.

  From this point of view, in the direction toward the one side in the sub-scanning direction among the first light emitting element array and the second light emitting element array, the upstream light emitting element array is the upstream side light emitting element array. It is preferable that the illuminance on the light irradiation surface is greater than the illuminance on the light irradiation surface of the document by the downstream light emitting element array.

  With this specific matter, it is possible to reduce a shadow that tends to appear at the upstream end of the document (particularly a thick document) placed on the document placement table in the direction toward one side in the sub-scanning direction.

In the illumination device according to the first and second aspects of the present invention, preferably, the light emitting element pitch in the arrangement direction of the plurality of light emitting elements is P, and the optical axis distance of the plurality of light emitting elements to the irradiated body. When H is H, the light emitting element pitch P and the optical axis distance H can be exemplified to satisfy the relationship of P / H ≦ 0.83.

  In this specific matter, the relationship between the light emitting element pitch P and the optical axis distance H can be optimized in a state in which the illuminance unevenness on the light irradiation surface of the irradiated object is reduced.

In the illuminating device according to the first aspect and the second aspect of the present invention, it is more preferable that the light emitting element pitch P and the optical axis distance H satisfy the relationship of P / H ≦ 0.71.

  In this specific matter, the relationship between the light emitting element pitch P and the optical axis distance H can be optimized in a state where the illuminance unevenness on the light irradiation surface of the irradiated body is further reduced.

  The relational expression of P / H ≦ 0.83 and the relational expression of P / H ≦ 0.71 will be described in detail in [Analysis simulation] described later.

  As described above, according to the present invention, based on the luminance rank, at least one of an optical axis distance to the irradiated object and a light irradiation position in a direction intersecting with the arrangement direction of the light emitting elements is determined. Since the light emitting element can be arranged so that it can be set, a commercially available light emitting element can be used over a wide range of luminance ranks without significantly changing the structure of the lighting device. It is possible to use a light emitting element in which cost reduction is realized.

1 is a side view schematically showing an image forming apparatus including an image reading apparatus to which an embodiment of an illumination device according to the present invention is applied. It is a schematic longitudinal cross-sectional view of the image reading apparatus shown in FIG. It is a figure which shows schematic structure of the light source unit which concerns on embodiment of this invention, Comprising: The figure (a) is the perspective view, and the figure (b) is the exploded perspective view. It is a figure which shows schematic structure of the light source in a light source unit, Comprising: The figure (a) is a side view of a light source unit, and the figure (b) is a side view of a light source. It is a schematic plan view of the board | substrate which arranged the some light emitting element in a line. It is a schematic side view which shows an example in which the several light emitting element is arranged only in the one side of a subscanning direction on the basis of a light irradiation area | region. BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic side view which shows an example of the several light emitting element which has a light emission surface which performs top surface light emission, Comprising: Fig.1 (a) performs top surface light emission with the 1st light emitting element and 2nd light emitting element which were arranged on both sides. FIG. 4B is a diagram illustrating an example in which the light emitting elements arranged on only one side emit light from the top surface. It is a top view which shows schematic structure of the light source substrate of 1st Embodiment. In the light source substrate of 1st Embodiment, it is a figure which shows a part of state in which the light emitting element of a 1st brightness | luminance rank is arrange | positioned at the 1st arrangement pattern row | line | column corresponding to a 1st brightness | luminance rank. In the light source substrate of 1st Embodiment, it is a figure which shows a part of state in which the light emitting element of a 2nd brightness | luminance rank is arrange | positioned at the 2nd arrangement pattern row | line | column corresponding to a 2 brightness | luminance rank. It is a figure which shows a part of state in which the light emitting element of a 3rd brightness | luminance rank is arrange | positioned in the arrangement | sequence pattern row | line corresponding to a 3rd brightness | luminance rank in the light source board | substrate of 1st Embodiment. It is a figure which shows the state by which the light emitting element of a different brightness | luminance rank is arrange | positioned at each corresponding arrangement pattern row | line | column. It is a side view which shows schematic structure of the light source board | substrate of 2nd Embodiment, Comprising: FIG. (A) is a figure which shows several types of board | substrates with mutually different thickness, FIG. (B) respond | corresponds to a 1st brightness | luminance rank. FIG. 4C is a diagram showing a second light source substrate corresponding to the second luminance rank, and FIG. 4D is a diagram corresponding to the third luminance rank. It is a figure which shows the light source substrate of the 3rd thickness to do. It is a figure which shows the 1st example of a setting of the optical axis distance of the 1st and 2nd light emitting element when the light emitting element row | line | column along a main scanning direction is arranged in parallel by 2 rows in a subscanning direction. It is a figure which shows the 2nd example of a setting of the optical axis distance of the 1st and 2nd light emitting element in case the light emitting element row | line | column along a main scanning direction is arranged in parallel at 2 rows in a subscanning direction. FIG. 6 is an explanatory diagram for explaining a shadow that is likely to appear when an image of a document placed on a platen glass is read. It is a figure for demonstrating the nonuniformity [%] M and the nonuniformity distance [mm] N in the light irradiation surface of the original by a 1st light emitting element and a 2nd light emitting element, Comprising: It repeats light and dark in the illuminance period of a main scanning direction. FIG. It is the figure which represented the determination result of the illumination intensity period T, amplitude [%] K, the distance between unevenness [mm] N calculated from these values, unevenness [%] M, and the printed image. FIG. 19 is a graph created based on the values shown in FIG. 18 with the unevenness [%] M as the vertical axis and the unevenness distance [mm] N as the horizontal axis. It is a figure for demonstrating the conditions of analysis simulation. 10 is a graph illustrating the illuminance [lx] on the light irradiation surface of the document with respect to the distance [mm] in the main scanning direction at a part of the optical axis distance in a part of the LED pitch used in the analysis simulation. Figures (a) and (b) are graphs in which the LED pitch is 8 mm and 10 mm, respectively. 10 is a graph illustrating the illuminance [lx] on the light irradiation surface of the document with respect to the distance [mm] in the main scanning direction at a part of the optical axis distance in a part of the LED pitch used in the analysis simulation. Figures (a) and (b) are graphs in which the LED pitch is 12 mm and 14 mm, respectively. 10 is a graph illustrating the illuminance [lx] on the light irradiation surface of the document with respect to the distance [mm] in the main scanning direction at a part of the optical axis distance in a part of the LED pitch used in the analysis simulation. Figures (a) and (b) are graphs in which the LED pitch is 16 mm and 18 mm, respectively. It is a figure for demonstrating nonuniformity [%] M at the time of using the light emitting element of a single row | line | column structure by setting LED pitch to 16 mm and optical axis distance to 6 mm. It is a figure which shows the determination result of P / H when LED pitch is made into the value of 1 mm increments of 4 mm-11 mm, and the optical axis distance was made into the value of 1 mm increments of 4 mm-24 mm. It is a figure which shows the determination result of P / H when LED pitch is made into the value of 1 mm increments of 12 mm-19 mm, and the optical axis distance was made into the value of 1 mm increments of 4 mm-24 mm. 24 under the conditions of FIG. 24 where the LED pitch is 16 mm and the optical axis distance is 6 mm, unevenness [%] when using the light emitting element having the same pitch position configuration shown in FIG. 5 (the illuminance is twice that of the single row configuration) It is a figure for demonstrating M. FIG. 1A and 1B are diagrams showing a conventional illumination device in which a plurality of light emitting elements are arranged on a substrate, in which FIG. 1A is a plan view of the illumination device, and FIG. It is the side view seen from. FIG. 29A is a diagram for explaining uneven illuminance on the light irradiation surface of the document by the light emitting element shown in FIG. 28, and FIG. 9A is a main scanning direction on the light irradiation surface of the document corresponding to the arrangement configuration of the light emitting elements. Is a graph of the illuminance with respect to the distance, and FIG. (B) is a diagram showing the arrangement configuration of the light emitting elements. It is a graph which shows an example of the luminance distribution of light emitting elements, such as LED.

  Embodiments according to the present invention will be described below with reference to the drawings. The following embodiments are examples embodying the present invention, and are not of a nature that limits the technical scope of the present invention.

  FIG. 1 is a side view schematically showing an image forming apparatus D including an image reading apparatus 100 to which an embodiment of an illumination device according to the present invention is applied.

  An image forming apparatus D shown in FIG. 1 reads an image of an original G (see FIG. 2 described later) and an image of the original G read by the image reading apparatus 100 or an image received from the outside. An apparatus main body Dd for recording on a recording sheet such as plain paper in color or single color.

[Overall Configuration of Image Forming Apparatus]
The apparatus main body Dd of the image forming apparatus D includes an exposure apparatus 1, a developing apparatus 2 (2a, 2b, 2c, 2d), a photosensitive drum 3 (3a, 3b, 3c, 3d) that functions as an image carrier, and a charger 5. (5a, 5b, 5c, 5d), cleaner device 4 (4a, 4b, 4c, 4d), intermediate transfer belt device 8 including intermediate transfer roller 6 (6a, 6b, 6c, 6d) acting as a transfer unit, fixing The apparatus 12 includes a sheet conveying device 50, a paper feed tray 10 that functions as a paper feed unit, and a paper discharge tray 15 that functions as a paper discharge unit.

  The image data handled in the apparatus main body Dd of the image forming apparatus D corresponds to a color image using each color of black (K), cyan (C), magenta (M), yellow (Y), or a single color (for example, This corresponds to a monochrome image using (black). Accordingly, the developing device 2 (2a, 2b, 2c, 2d), the photosensitive drum 3 (3a, 3b, 3c, 3d), the charger 5 (5a, 5b, 5c, 5d), and the cleaner device 4 (4a, 4b, 4c, 4d) and four intermediate transfer rollers 6 (6a, 6b, 6c, 6d) are provided so as to form four types of images corresponding to the respective colors. Is associated with black, b with cyan, c with magenta, and d with yellow to form four image stations. Hereinafter, the description will be made with the suffixes a to d omitted.

  The photoconductive drum 3 is disposed substantially at the center in the vertical direction of the apparatus main body Dd. The charger 5 is a charging means for uniformly charging the surface of the photosensitive drum 3 to a predetermined potential. In addition to a contact type roller type or brush type charger, a charger type charger is used. .

  Here, the exposure apparatus 1 is a laser scanning unit (LSU) provided with a laser diode and a reflection mirror, and exposes the surface of the charged photosensitive drum 3 according to image data, and according to the image data on the surface. An electrostatic latent image is formed.

  The developing device 2 develops the electrostatic latent image formed on the photosensitive drum 3 with (K, C, M, Y) toner. The cleaner device 4 removes and collects toner remaining on the surface of the photosensitive drum 3 after development and image transfer.

  In addition to the intermediate transfer roller 6, the intermediate transfer belt device 8 disposed above the photosensitive drum 3 includes an intermediate transfer belt 7, an intermediate transfer belt drive roller 21, a driven roller 22, a tension roller 23, and an intermediate transfer belt. A cleaning device 9 is provided.

  Roller members such as the intermediate transfer belt drive roller 21, the intermediate transfer roller 6, the driven roller 22, and the tension roller 23 stretch and support the intermediate transfer belt 7, and the intermediate transfer belt 7 is supported in a predetermined sheet conveyance direction (in the drawing). Move around in the direction of the arrow).

  The intermediate transfer roller 6 is rotatably supported inside the intermediate transfer belt 7 and is pressed against the photosensitive drum 3 via the intermediate transfer belt 7.

  The intermediate transfer belt 7 is provided so as to be in contact with each photoconductive drum 3, and a color toner image (each color is transferred by sequentially superimposing and transferring the toner image on the surface of each photoconductive drum 3 onto the intermediate transfer belt 7. Toner image). Here, the transfer belt 7 is formed in an endless belt shape using a film having a thickness of about 100 μm to 150 μm.

  The transfer of the toner image from the photosensitive drum 3 to the intermediate transfer belt 7 is performed by the intermediate transfer roller 6 that is in pressure contact with the inner side (back surface) of the intermediate transfer belt 7. A high voltage transfer bias (for example, a high voltage having a polarity (+) opposite to the toner charging polarity (−)) is applied to the intermediate transfer roller 6 in order to transfer the toner image. Here, the intermediate transfer roller 6 is a roller based on a metal (for example, stainless steel) shaft having a diameter of 8 to 10 mm and whose surface is covered with a conductive elastic material (for example, EPDM, urethane foam, or the like). With this conductive elastic material, a high voltage can be uniformly applied to the recording sheet.

  The apparatus main body Dd of the image forming apparatus D further includes a secondary transfer apparatus 11 including a transfer roller 11a that functions as a transfer unit. The transfer roller 11a is in contact with the opposite side (outside) of the intermediate transfer belt 7 from the intermediate transfer belt drive roller 21.

  As described above, the toner images on the surfaces of the respective photosensitive drums 3 are stacked on the intermediate transfer belt 7 and become a color toner image indicated by the image data. The stacked toner images of the respective colors are transported together with the intermediate transfer belt 7 and transferred onto the recording sheet by the secondary transfer device 11.

  The intermediate transfer belt 7 and the transfer roller 11a of the secondary transfer device 11 are pressed against each other to form a nip region. The transfer roller 11a of the secondary transfer device 11 has a voltage (for example, a polarity (+) opposite to the toner charging polarity (-)) for transferring the toner image of each color on the intermediate transfer belt 7 to the recording sheet. Is applied). Further, in order to constantly obtain the nip region, either the transfer roller 11a of the secondary transfer device 11 or the intermediate transfer belt drive roller 21 is made of a hard material (metal or the like), and the other is a soft material such as an elastic roller. (Elastic rubber roller, foaming resin roller, etc.).

  In addition, the toner image on the intermediate transfer belt 7 may not be completely transferred onto the recording sheet by the secondary transfer device 11, and the toner may remain on the intermediate transfer belt 7. Causes color mixing. Therefore, the residual toner is removed and collected by the intermediate transfer belt cleaning device 9. The intermediate transfer belt cleaning device 9 includes, for example, a cleaning blade that comes into contact with the intermediate transfer belt 7 as a cleaning member, and residual toner can be removed and collected by the cleaning blade. The driven roller 22 supports the intermediate transfer belt 7 from the inside (back side), and the cleaning blade is in contact with the intermediate transfer belt 7 so as to press the driven roller 22 from the outside.

  The paper feed tray 10 is a tray for storing recording sheets, and is provided below the image forming unit of the apparatus main body Dd. A paper discharge tray 15 provided on the upper side of the image forming unit is a tray for placing printed recording sheets face down.

  In addition, the apparatus main body Dd is provided with a sheet conveying device 50 for sending the recording sheet on the paper feed tray 10 to the paper discharge tray 15 via the secondary transfer device 11 and the fixing device 12. The sheet conveying apparatus 50 has an S-shaped sheet conveying path S, and along the sheet conveying path S, a pickup roller 16, a roller roller 14a, a separation roller 14b, each conveying roller 13, a pre-registration roller pair 19, Conveying members such as the registration roller pair 106, the fixing device 12, and the paper discharge roller 17 are disposed.

  The pickup roller 16 is a pull-in roller that is provided at the downstream end of the sheet feeding tray 10 in the sheet conveying direction and supplies recording sheets from the sheet feeding tray 10 to the sheet conveying path S one by one. The separating roller 14a passes the recording sheet between the separating roller 14b and conveys it to the sheet conveying path S while separating the recording sheets one by one. Each conveyance roller 13 and the pre-registration roller pair 19 are small rollers for promoting and assisting conveyance of the recording sheet. Each conveying roller 13 is provided at a plurality of locations along the sheet conveying path S. The pre-registration roller pair 19 is provided in the immediate vicinity of the registration roller pair 106 on the upstream side in the sheet conveyance direction, and conveys the recording sheet to the registration roller pair 106.

  The registration roller 106 temporarily stops the recording material conveyed by the pre-registration roller 19, aligns the leading edge of the recording sheet, and moves on the intermediate transfer belt 7 in the nip region between the intermediate transfer belt 7 and the secondary transfer device 11. In order to transfer the color toner image onto the recording sheet, the recording material is conveyed in a timely manner as the photosensitive drum 3 and the intermediate transfer belt 7 rotate.

  For example, the registration roller 106 performs recording so that the leading end of the color toner image on the intermediate transfer belt 7 matches the leading end of the image forming range on the recording sheet in the nip region between the intermediate transfer belt 7 and the secondary transfer device 11. Transport the sheet.

  The fixing device 12 includes a heat roller 31 and a pressure roller 32. The heat roller 31 and the pressure roller 32 sandwich and convey the recording sheet.

  The temperature of the heat roller 31 is controlled so as to be a predetermined fixing temperature, and the recording sheet is thermocompression bonded together with the pressure roller 32 to melt, mix, and press the toner image transferred to the recording sheet. On the other hand, it has a function of heat fixing. The fixing device 12 is provided with an external heating belt 33 for heating the heat roller 31 from the outside.

  The recording sheet after fixing the toner images of the respective colors is discharged onto the paper discharge tray 15 by the paper discharge roller 17.

  It is also possible to form a monochrome image using at least one of the four image forming stations and transfer the monochrome image to the intermediate transfer belt 7 of the intermediate transfer belt device 8. Similarly to the color image, this monochrome image is also transferred from the intermediate transfer belt 7 to the recording sheet and fixed on the recording sheet.

  In addition, when performing image formation on both the front side and the front side of the recording sheet, the image on the surface of the recording sheet is fixed by the fixing device 12, and then the recording sheet is discharged on the sheet conveying path S in the sheet discharge roller 17. In the middle of the conveyance, the paper discharge roller 17 is stopped and then reversely rotated, the recording sheet is passed through the front / back reversing path Sr, the recording sheet is reversed, and the recording sheet is transferred to the registration roller pair 106 again. As in the case of the front surface of the recording sheet, the image is recorded and fixed on the back surface of the recording sheet, and the recording sheet is discharged to the paper discharge tray 15.

[Overall configuration of image reading apparatus]
FIG. 2 is a schematic longitudinal sectional view of the image reading apparatus 100 shown in FIG. The image reading apparatus 100 shown in FIGS. 1 and 2 is configured to read a document image by fixing the document G by a document fixing method and to read a document image by moving the document G by a document moving method. .

  In other words, the image reading apparatus 100 includes a document fixed reading configuration and a document moving reading configuration.

  In the document fixed reading configuration, a document G placed on a document table glass 201a, which is an example of a document table, is illuminated by a light source unit 210 (an example of an illumination device) through the glass 201a. While moving 210 in the sub-scanning direction (one side in the direction of arrow Y in the figure), the reflected light from the original G illuminated by the light source unit 210 is in the main scanning direction (the arrow in FIG. 3 to be described later) orthogonal to the sub-scanning direction Y. The original image is read by scanning in the X direction).

  In the document moving and reading configuration, the document reading unit 200 feeds a document G conveyed to one side in the sub-scanning direction Y so as to pass over a document reading glass 201b which is another example of a document table by the automatic document feeder 300. While the light source unit 210 located at the fixed position V is illuminated through the glass 201b, the reflected light from the original G illuminated by the light source unit 210 is scanned in the main scanning direction X to read the original image. FIG. 2 shows a state where the light source unit 210 is located at the fixed position V.

  Specifically, the document reading unit 200 includes a document table glass 201a, a light source unit 210, an optical system driving unit (not shown) that moves the light source unit 210, a mirror unit 203, a condensing lens 204, and an image sensor (CCD here). 205, and these members are accommodated in a metal frame 202. The light source unit 210 includes a light source 211 that irradiates light toward the original G, and a first mirror 230 that guides reflected light from the original G to the mirror unit 203. The light source unit 210 will be described in detail later.

  The document table glass 201 a is made of a transparent glass plate, and both ends in the main scanning direction X are placed on the frame body 202. The automatic document feeder 300 can be opened and closed with respect to the document reading unit 200 around an axis along the sub-scanning direction Y (for example, supported by a hinge), and the lower surface thereof is the document of the document reading unit 200. It also serves as a document pressing member that presses the document G placed on the table glass 201a from above.

  The mirror unit 203 includes a second mirror 203a, a third mirror 203b, and a support member (not shown). The support member supports the second mirror 203a so that light from the first mirror 230 in the light source unit 210 is reflected and guided to the third mirror 203b. Further, the support member supports the third mirror 203b so as to reflect the light from the second mirror 203a and guide it to the condenser lens 204. The condensing lens 204 condenses the light from the third mirror 203b on the image sensor 205. The image sensor 205 converts light (original image light) from the condenser lens 204 into an electrical signal as image data.

  The optical system driving unit moves the light source unit 210 in the sub-scanning direction Y at a constant speed, and similarly moves the mirror unit 203 in the sub-scanning direction Y at a moving speed that is ½ of the moving speed of the light source unit 210. It is configured to move.

  Here, the document reading unit 200 is compatible with a document moving method in addition to a document fixing method, and includes a document reading glass 201b. Accordingly, the optical system driving unit is further configured to position the light source unit 210 at a predetermined home position V below the document reading glass 201b.

  The automatic document feeder 300 includes a document tray 301 for placing the document G, a discharge tray 302 disposed below the document tray 301, and a first transport path 303 connecting the two. Two transport roller pairs including an upstream transport roller pair 304 and a downstream transport roller pair 305 are provided.

  The upstream side conveyance roller pair 304 conveys the original G on the upstream side in the conveyance direction Y1 of the original G with reference to the original reading glass 201b. The downstream conveying roller pair 305 conveys the document G on the downstream side in the conveyance direction Y1 of the document G with reference to the document reading glass 201b. That is, the upstream conveyance roller pair 304, the document reading glass 201b, and the downstream conveyance roller pair 305 are arranged in this order along the conveyance direction Y1. The document reading glass 201b is provided substantially horizontally so as to delineate the transport wall of the first transport path 303.

  The automatic document feeder 300 further includes a pickup roller 306, a roller roller 307, and a separation member 308 such as a separation pad.

  The pickup roller 306 feeds the document G placed on the document tray 301 from the document tray 301 into the first transport path 303 along the transport direction Y1. The suction roller 307 is disposed downstream of the pickup roller 306 in the conveyance direction Y1, and further conveys the original G sent by the pickup roller 306 together with the separating member 308 further downstream in the conveyance direction Y1. . The separating member 308 is configured to scoop (separate) the original G so that the original G conveyed between the separating roller 307 and the separating roller 307 is one sheet.

  In the automatic document feeder 300 having such a configuration, the document G is conveyed between the separating roller 307 and the separating member 308 by the pickup roller 306, and the document G is separated by being separated and the separating roller 307 is rotationally driven. As a result, the sheets are conveyed one by one. The document G conveyed by the roller roller 307 is guided along the first conveyance path 303 and is supplied one by one toward the upstream conveyance roller pair 304.

  Specifically, the pickup roller 306 can be brought into and out of contact with the original G loaded on the original tray 301 by a pickup roller driving unit (not shown). The pickup roller 306 is coupled to the roller roller 307 so as to rotate in the same direction as the roller roller 307 via a drive transmission means 309 including an endless belt. When a reading request for the document G is made, the pickup roller 306 and the roller 307 are rotationally driven in a direction (arrow W in FIG. 2) in which the document G is transported in the transport direction Y1 by a document supply driving unit (not shown). It has become.

  In the present embodiment, the automatic document feeder 300 can read one side of the original G by reversing the original G so that the front and back sides are reversed after conveying one side of the original G in a readable manner. It is comprised so that it may convey.

  Specifically, the automatic document feeder 300 further includes a reverse roller pair 310, a second conveyance path 311, and a switching claw 312 in addition to the above configuration.

  The first conveyance path 303 is formed in a loop shape so as to convey the original G from the suction roller 307 to the upstream side conveyance roller pair 304, the original reading glass 201 b, the downstream side conveyance roller pair 305, and the reverse roller pair 310. Has been. The reverse roller pair 310 is disposed on the downstream side in the transport direction Y1 with respect to the downstream transport roller pair 305, and the document G transported from the downstream transport roller pair 305 is rear end (upstream end in the transport direction Y1). ) For transporting in front. The second conveyance path 311 is branched from a branch portion Sd between the reverse roller pair 310 and the downstream-side conveyance roller pair 305, and the original conveyed by the reverse roller pair 310 so that the trailing edge is forward. In order to reverse G so that the front and back of the original G are reversed, the G is guided upstream in the transport direction Y1 from the upstream transport roller pair 304 of the first transport path 303. A switchback conveyance path 313 is formed between the reverse roller pair 310 of the first conveyance path 303 and the branch portion Sd. The switchback conveyance path 313 is a conveyance path that can convey the original G by rotating the reverse roller pair 310 in the forward direction (conveyance direction Y1 of the original G) and reversely convey the original G by rotating in the reverse direction. ing.

  The switching claw 312 is disposed at the branch portion Sd, and has a first switching posture for guiding the original G from the reverse roller pair 310 to the upstream conveying roller pair 304 via the second conveying path 311 and the original G on the downstream side. It is configured to be able to take a second switching posture that leads from the roller pair 305 to the reverse roller pair 310 via the switchback conveyance path 313.

  Here, in a normal state, the switching claw 312 is arranged in a form in which the switchback conveyance path 313 and the second conveyance path 311 are directly connected (first switching posture, see solid line in FIG. 2). When the document G on which the image has been read is transported in the transport direction Y1, the leading edge of the document G (the end on the downstream side in the transport direction Y1) pushes up the switching claw 312 to guide the document G to the switchback transport path 313. (Refer to the second switching posture, broken line in the figure). The branching claw 312 has a reversing roller such that the claw portion 312a falls by its own weight, closes the first conveying path 303 between the downstream conveying roller pair 305 and the reversing roller pair 310 and takes the first switching posture. It can be swung around a swing axis Q along the axial direction of the pair 311. Then, the switching claw 312 has the rear end of the document G positioned in the switchback transport path 313, and the reverse of the transport direction Y1 of the document G is reversed by the reverse roller pair 310 in which the document G rotates in the reverse direction. The document G is guided to the second transport path 311 when transported backward in the transport direction (arrow Y2 direction in the figure).

  Note that the size of the document G placed on the document tray 301 is detected by a document size sensor 314 disposed in the document placement portion of the document tray 301. Presence / absence of the document G placed on the document tray 301 is detected by a document presence / absence detection sensor 315 disposed in the vicinity of the pickup roller 306 of the document placement portion of the document tray 301. In addition, the upstream-side transport roller pair 304 is adapted to abut and align the leading edge of the document G transported by the roller roller 307 in the stopped state, and is driven to rotate in accordance with the read timing. The original G thus transported is detected by a transport sensor 316 disposed downstream of the second transport path 311 and downstream of the upstream transport roller pair 304 in the transport direction Y1 of the first transport path 303. It is like that. The document G discharged by the reverse roller pair 310 is detected by a discharge sensor 317 disposed near the reverse roller pair 310 on the discharge side of the reverse roller pair 310. The conveyance system rollers such as the conveyance roller pairs 304 and 305 and the reverse roller pair 310 are driven by a conveyance system drive unit (not shown).

  In the present embodiment, the document conveying section 200 further includes a reading guide 318 that faces the document reading glass 201b with the conveyed document G in between.

  In the image reading apparatus 100 described above, when an instruction to read the original image of the original G is given by the original fixing method, the light source unit 210 emits light to the original G placed on the original table glass 201a. While irradiating through 201 a, the image of the original G is scanned by moving to one side in the sub-scanning direction Y at a constant speed, and at the same time, the mirror unit 203 is moving at half the moving speed of the light source unit 210. Similarly, it moves to one side in the sub-scanning direction Y.

  The reflected light that is illuminated by the light source unit 210 and reflected from the original G is reflected by the first mirror 230 provided in the light source unit 210 and then 180 by the second and third mirrors 203 a and 203 b of the mirror unit 203. ° The optical path is changed. The light reflected from the third mirror 203b forms an image on the image sensor 205 via the condenser lens 204, where the original image light is read and converted into electrical image data.

  On the other hand, when an instruction to read the original image of the original G is given by the original moving method, the automatic original feeder 300 keeps the light source unit 210 and the mirror unit 203 stationary at the position V shown in FIG. Is conveyed to one side in the sub-scanning direction Y so as to pass the upper part of the position V shown in FIG. In other words, the original G placed on the original tray 301 is taken out by the pickup roller 306, separated one by one by the separating roller 307 and the separating member 308, and conveyed to the first conveying path 303. After the document G transported to the first transport path 303 is confirmed by the transport sensor 316 to transport the document G, the upstream transport roller pair 304 aligns the leading edge to prevent skew feeding and provides a prescribed reading. It is sent out at the timing, and the front and back sides are reversed and conveyed to the original reading glass 201b.

  Then, light from the light source unit 210 is applied to one surface of the original G that has passed over the original reading glass 201b through the original reading glass 201b and reflected by the one surface. The light reflected from one surface of the original G is reflected by the first mirror 230 in the same manner as the original fixing method described above, and then the optical path is changed by 180 ° by the second and third mirrors 203a and 203b of the mirror unit 203. Then, an image is formed on the image sensor 205 via the condenser lens 204, where the original image is read and converted into electrical image data. Note that the reading operation by the image sensor 205 is the same in the case of double-sided reading to be described later, and will not be described below.

  The document G that has been read is pulled out from the reading glass 201 b by the downstream conveying roller pair 305, and is discharged through the switchback conveying path 313 of the first conveying path 303 by the reversible roller pair 310 that can be rotated reversibly. Discharged to the top.

  Further, when reading both sides of one side and the other side of the original G, the original G on which one side is read is not discharged to the discharge tray 302, and the rear end of the original G is switched back. The reversing roller pair 310 that is transported so as to be positioned in the transport path 313, is reversely transported in the reverse transport direction Y2 by the pair of reverse rollers 310 that rotates in the reverse direction, and is guided to the second transport path 311 by the switching claw 312 in the first switching posture. It is burned. The original G guided to the second conveyance path 311 returns to the first conveyance path 303 again via the second conveyance path 311, so that the front and back are reversed and conveyed by the upstream conveyance roller pair 304. The other surface is read through the document reading glass 201b. The original G that has been read on both sides is returned to the first conveyance path 303 again, so that the front and back are reversed and conveyed by the conveyance roller pairs 304 and 305, and then the switchback conveyance of the first conveyance path 303 is performed. The paper passes through the path 313 and is discharged to the discharge tray 302 via the reverse roller pair 310 rotating in the forward direction.

  FIG. 3 is a diagram showing a schematic configuration of the light source unit 210 according to the embodiment of the present invention. FIG. 3 (a) shows a perspective view thereof, and FIG. 3 (b) shows an exploded perspective view thereof. 4A and 4B are diagrams showing a schematic configuration of the light source 211 in the light source unit 210. FIG. 4A shows a side view of the light source unit 210, and FIG. 4B shows a side view of the light source 211. Is shown. In FIG. 4, document tables 201a and 201b and document G are also shown.

  5 shows a schematic plan view of a substrate 213 in which a plurality of light emitting elements 212,.

  In the light source unit 210 according to the embodiment of the present invention, light from a plurality of light emitting elements 212 arranged on a substrate (hereinafter referred to as a light source substrate) 213 is irradiated with light from an object to be irradiated (here, the original G). Irradiation is directed toward the surface Gd.

  The light source 211 provided in the light source unit 210 includes a plurality of light emitting elements 212, and a light source substrate 213 on which the light emitting elements 212 are mounted. The plurality of light emitting elements 212,... Are all light emitting diode (LED) elements. Each of the light emitting elements 212,... Has a strong directional characteristic in a predetermined direction. The direction in which the luminous flux is the strongest among the light emitted from the light emitting elements 212,. Each light emitting element is of the same type (here, the same manufacturer).

  The plurality of light emitting elements 212,... Irradiate light toward a predetermined light irradiation region Ld side extending in a predetermined first direction (here, the main scanning direction X) in the document G. This light irradiation region Ld is set as a document reading position.

  In the present embodiment, the plurality of light emitting elements 212,... Are in the second direction (here, the sub-scanning direction Y) along the light irradiation surface Gd orthogonal to the main scanning direction X with reference to the light irradiation region Ld. It is lined up on both sides. The plurality of light emitting elements 212,... Are arranged such that each optical axis L is perpendicular to the main scanning direction X.

  Specifically, the plurality of light emitting elements 212,... Have a plurality of first light emitting elements 212a,... Arranged in the main scanning direction X on one side, and a plurality of second light emitting elements 212,. .. Are arranged in the main scanning direction X. That is, the plurality of light emitting elements 212,... Are a first light emitting element array 220a composed of the first light emitting elements 212a,... And a second light emitting element array 220b composed of the plurality of second light emitting elements 212b,. Arranged in two rows.

  The light source substrate 213 includes first and second light source substrates 213a and 213b extending in the main scanning direction X and parallel to each other. The plurality of first light emitting elements 212a,... Are mounted on the first light source substrate 213a, and the plurality of second light emitting elements 212b,.

  In the present embodiment, the light emitting element pitches (distances between element centers in the main scanning direction X) P of the plurality of first light emitting elements 212a,... And the plurality of second light emitting elements 212b,. It is said that the distance. Further, in the first light emitting element row and the second light emitting element row, the first light emitting elements 212a, ... and the second light emitting elements 212b, ... are arranged so that their pitch positions are aligned in the sub-scanning direction Y (same pitch position configuration). Are arranged). Here, the first light emitting elements 212a,... And the second light emitting elements 212b,.

  In the present embodiment, as shown in FIG. 4B, the plurality of first light emitting elements 212a,... And the plurality of second light emitting elements 212b,. The second light source substrate 213b has a light emitting surface E1 that performs side light emission for emitting light so that the optical axis L is parallel to the arrangement surface F of the light emitting elements. Specifically, the first light source substrate 213a on which the first light emitting elements 212a,... Are mounted and the second light source substrate 213b on which the second light emitting elements 212b,. It is arranged in a “C” shape with the side opposite to the original G side opened so as to face the irradiation region Ld side. Note that the light irradiation region Ld is located between the first light source substrate 213a and the second light source substrate 213b.

  In the configuration of the light source unit 210 described above, the plurality of light emitting elements 212,... Are arranged on both sides in the sub-scanning direction Y with reference to the light irradiation region Ld, but may be arranged only on one side. .

  FIG. 6 is a schematic side view showing an example in which the plurality of light emitting elements 212,... Are arranged only on one side in the sub-scanning direction Y with reference to the light irradiation region Ld.

  6 are mounted on a light source substrate 213 arranged on one side in the sub-scanning direction Y with respect to the light irradiation region Ld, and the optical axis L is parallel to the arrangement surface F. The light emitting elements 212,. It has the light emission surface E1 which performs side light emission which inject | emits light so that it may become. Specifically, the light source substrate 213 is inclined and disposed so that the direction of the optical axis L is directed to the light irradiation region Ld side.

  Further, regardless of whether the plurality of light emitting elements 212,... Are arranged on both sides or only on one side, the optical axis L is perpendicular to the arrangement surface F of the mounted light source substrate 213. You may perform top surface light emission which inject | emits light.

  FIG. 7 is a schematic side view showing an example of a plurality of light emitting elements 212,... Having a light emitting surface E2 that emits top surface light. 7A shows an example in which the first light emitting elements 212a,... And the second light emitting elements 212b,... Arranged on both sides emit top surface light, and FIG. An example is shown in which the light emitting elements 212,.

  As shown in FIG. 7A, when the first light emitting elements 212a,... And the second light emitting elements 212b,... Have the light emitting surface E2 that emits the top surface, the direction of the optical axis L is the light irradiation region Ld. The first light source substrate 213a and the second light source substrate 213b can be arranged in an inverted “C” shape with the document G side open so as to face the side. Note that the light irradiation region Ld is located between the first light source substrate 213a and the second light source substrate 213b.

  7B, when the light emitting elements 212,... Are arranged on only one side, the light source substrate 213 is inclined so that the direction of the optical axis L faces the light irradiation region Ld. can do.

  Thus, the light emitting elements can be arranged as shown in FIGS. 4 to 7. However, when the light emitting elements are arranged at the same pitch position on both sides as shown in FIG. 5, FIG. 6 and FIG. As shown in FIG. 7B, the illuminance can be doubled by doubling the number of light emitting elements as compared with the configuration in which the light emitting elements are arranged only on one side.

  In addition, when the light emitting element emits one of side light emission and top surface light emission, according to the arrangement configuration of the components in the light source unit 210, the side light emission structure and the top surface light emission structure By properly using these, the vacant space in the light source unit 210 can be used effectively.

  As shown in FIG. 3, the light source unit 210 includes a light emitting element array unit 215 and a mirror base unit 216 provided with the light emitting element array unit 215.

  The light emitting element array unit 215 includes a first light emitting element 212a, ..., a first light source substrate 213a, a second light emitting element 212b, ..., a second light source substrate 213b, a first light source substrate 213a, and a second light source substrate 213b. And a base 214 provided with.

  Specifically, the first light source substrate 213a and the second light source substrate 213b are arranged on the base 214 so that the longitudinal direction is directed to the main scanning direction X. The base 214 fixes the first and second light source substrates 213a and 213b with fixing members SC such as screws at both ends in the main scanning direction X at a predetermined interval in the sub scanning direction Y. Thus, the first light emitting elements 212a,... And the second light emitting elements 212b,... Are arranged in rows along the main scanning direction X on both sides in the sub-scanning direction Y with reference to the light irradiation region Ld.

  The base 214 is further formed with a slit R extending along the main scanning direction X for allowing the reflected light from the document G to pass between the first light source substrate 213a and the second light source substrate 213b. . The slit R is located below the light irradiation region Ld that is the document reading position. That is, the first light emitting element row 220a and the second light emitting element row 220b are arranged on both sides of the slit R in the short direction.

  The mirror base unit 216 is provided with a first mirror 230. Specifically, the first mirror 230 guides the light reflected from the light irradiation surface Gd of the document G to the second mirror 203a of the mirror unit 203 through the slit R provided on the base 214. It is supported in a state of being inserted through the opening 216a along the main scanning direction X.

[Description of Features of the Present Invention]
In the light source unit 210, the first and second light emitting elements (212a,...), (212b,...) Are light emitting elements ranked in a specific luminance rank set in advance with respect to the luminance of the emitted light. .

  As shown in FIG. 30, the first and second light emitting elements (212a,...), (212b,...) Have a certain luminance range, and a plurality of luminance ranks R1,. , Rn (n is an integer of 2 or more).

  The light source unit 210 has a plurality of lights as the optical axis distance H to the original G of the first and second light emitting elements (212a,...), (212b,...) Based on any of the plurality of luminance ranks R1,. The first and second light emitting elements (212a,...), (212b,...) Can be arranged so that any one of the axial distances H1,. Alternatively / further, the light source unit 210 sets any one of a plurality of light irradiation positions as a light irradiation position in the sub-scanning direction Y on the document G with the optical axis L based on any one of the plurality of luminance ranks R1,. The first and second light emitting elements (212a,...), (212b,...) Can be arranged so that they can be changed.

  Specifically, the first and second light source substrates 213a and 213b are substrates on which the first and second light emitting elements (212a,...), (212b,...) Can be arranged based on a plurality of luminance ranks R1,. Prepared in advance.

  Then, as in the first and second embodiments described below, the light irradiation position in the optical axis distance H and / or the sub-scanning direction Y is determined based on one of the plurality of luminance ranks R1,. 1 and the second light source substrates 213a and 213b. In the following first and second embodiments, the first light emitting elements 212a,... And the second light emitting elements 212b,. 213b will be described simply as the light source substrate 213.

(First embodiment)
In the first embodiment, as shown in FIGS. 4, 6, and 7, the light source substrate 213 has the arrangement surface F inclined with respect to the light irradiation surface Gd of the document G around an axis along the main scanning direction X. Are arranged as follows.

  The light source substrate 213 may be arranged such that the arrangement surface F is perpendicular to or parallel to the light irradiation surface Gd of the document G. In this case, the light emitting element 212 is preferably arranged on the light source substrate 213 so that the direction of the optical axis L is inclined with respect to the arrangement surface F of the light source substrate 213 (toward the light irradiation region Ld side).

  FIG. 8 is a plan view showing a schematic configuration of the light source substrate 213 of the first embodiment. On the light source substrate 213 shown in FIG. 8, a plurality of arrangement pattern rows PT1,..., PTn are sequentially formed along the sub-scanning direction Y according to the plurality of luminance ranks R1,.

  In the plurality of arrangement pattern rows PT1,..., PTn, a plurality of arrangement (electrode) patterns pt for arranging (mounting) the light emitting elements 212,. ) Are arranged along each. That is, the plurality of arrangement pattern rows PT1,..., PTn are formed in order along the short direction of the light source substrate 213.

  The light emitting elements 212,... Of the luminance ranks R1,..., Rn are arranged in the arrangement pattern rows P1,..., PTn corresponding to the luminance ranks R1,.

  The arrangement pattern pt constituting the plurality of arrangement pattern rows PT1,..., PTn is a matrix arrangement pattern (pt11) in which m (m is an integer of 2 or more) in the main scanning direction X and n in the sub scanning direction Y are arranged. , Pt21, ..., ptm1), ..., (pt1n, pt2n, ..., ptmn).

  As the arrangement pattern pt for placing the light emitting elements 212 and 212 adjacent to each other in the main scanning direction X (see the two-dot chain line in FIG. 8) on both sides, an H-shaped arrangement pattern formed in an H shape in plan view can be exemplified. In this H-shaped arrangement pattern, light emitting elements adjacent in the main scanning direction X can be placed with the area of the arrangement pattern being suppressed as much as possible.

  Specifically, the H-shaped arrangement pattern pt includes a first placement part pta to which one terminal of one light emitting element among the light emitting elements 212 and 212 adjacent in the main scanning direction X is electrically connected, and the other. It consists of a second mounting part ptb to which the other terminal of the light emitting element is electrically connected, and a connecting part ptc that electrically connects the first mounting part pta and the second mounting part ptb.

  In each arrangement pattern row PT, the remaining arrangement pattern pt excluding the arrangement patterns pt at both ends in the main scanning direction X can be set as an H-shaped arrangement pattern pt. Here, any one of the arrangement patterns pt at one end (the left end in FIG. 8) in the main scanning direction X is electrically connected to the first electrode wiring pattern ptd. In addition, the arrangement pattern pt at the other end (the right end in FIG. 8) in the main scanning direction X is electrically connected to the second electrode wiring pattern pte. The first electrode wiring pattern ptd and the second electrode wiring pattern pte are electrically connected to a drive circuit (not shown) for driving the light emitting elements 212,.

  In the light source substrate 213 having such a configuration, for example, when the optical axis L is parallel to the arrangement surface F as in the case of performing side light emission as shown in FIGS. One of the plurality of optical axis distances H1,..., Hn can be set and changed as the optical axis distance H while maintaining the position. That is, one of the plurality of optical axis distances H1,..., Hn is set as the optical axis distance H based on one of the plurality of luminance ranks R1,. Can be arranged in the arrangement pattern row. Further, when the optical axis L is not parallel to the arrangement surface F, at least the light irradiation position in the sub-scanning direction Y is changed among the optical axis distance H and the light irradiation position in the sub-scanning direction Y. be able to.

  For example, in the case where the plurality of luminance ranks R1,..., Rn are from the first luminance rank R1 to the third luminance rank R3, and the first to third arrangement pattern rows PT1 to PT3 are formed on the light source substrate 213 as an example. This will be described below. In this case, one of the first to third optical axis distances H1 to H3 (H1 <H2 <H3) is changed as the optical axis distance H according to the first to third luminance ranks R1 to R3. be able to.

  Here, among the first luminance rank R1 to the third luminance rank R3, the illuminance on the light irradiation surface Gd of the original G is set to an appropriate illuminance in the light emitting element 212 of the darkest first luminance rank R1, and The optical axis distance H that can make illuminance unevenness inconspicuous is defined as a first optical axis distance H1. Further, in the light emitting elements 212,... Of the second brightness rank R2 having intermediate brightness, the light that can make the illuminance on the light irradiation surface Gd of the original G appropriate illuminance and make the illuminance unevenness inconspicuous. The axial distance H is set as the second optical axis distance H2. Further, in the light emitting elements 212,... Of the brightest third luminance rank R3, the optical axis distance H that makes the illuminance on the light irradiation surface Gd of the document G appropriate illuminance and makes illuminance unevenness inconspicuous. The third optical axis distance is H3. The same applies to the second embodiment described later.

  FIG. 9 shows a part of the light source substrate 213 in a state where the light emitting elements 212 of the first luminance rank R1 are arranged in the first arrangement pattern row PT1 corresponding to the first luminance rank R1. FIG. 10 shows a part of the light source substrate 213 in which the light emitting elements 212,... Of the second luminance rank R2 are arranged in the second arrangement pattern row PT2 corresponding to the second luminance rank R2. 11 shows a part of the light source substrate 213 in which the light emitting elements 212,... Of the third luminance rank R3 are arranged in the arrangement pattern row PT3 corresponding to the third luminance rank R2. 9 to 12, the second electrode wiring pattern pte is not shown.

  As shown in FIG. 9, when the light emitting elements 212,... Having the darkest first luminance rank R1 are arranged in the first arrangement pattern row PT1 corresponding to the first luminance rank R1, the optical axes of the light emitting elements 212,. The distance H is the first optical axis distance H1. Therefore, the illuminance on the light irradiation surface Gd of the original G by the light emitting elements 212,... Arranged in the first arrangement pattern row PT1 can be set to an appropriate illuminance, and uneven illuminance can be made inconspicuous.

  As shown in FIG. 10, when the light emitting elements 212 of the second brightness rank R2 having intermediate brightness are arranged in the second arrangement pattern row PT2 corresponding to the second brightness rank R2, the light emitting elements 212, The optical axis distance H is a second optical axis distance H2. Therefore, the illuminance on the light irradiation surface Gd of the original G by the light emitting elements 212,... Arranged in the second arrangement pattern row PT2 can be set to an appropriate illuminance, and uneven illuminance can be made inconspicuous.

  11, when the light emitting elements 212,... Of the brightest third luminance rank R3 are arranged in the arrangement pattern row PT3 corresponding to the third luminance rank R2, the optical axes of the light emitting elements 212,. The distance H is the third optical axis distance H3. Therefore, the illuminance on the light irradiation surface Gd of the original G by the light emitting elements 212,... Arranged in the third arrangement pattern row PT3 can be set to an appropriate illuminance, and uneven illuminance can be made inconspicuous.

  In the first embodiment, as shown in FIGS. 9 to 11, the light emitting elements 212,... Having the same luminance rank may be arranged in a line corresponding to the same arrangement pattern, but the present invention is not limited thereto. Instead, the light emitting elements 212,... Having different luminance ranks may be arranged in the corresponding arrangement pattern rows.

  FIG. 12 shows a state in which the light emitting elements 212,... Having different luminance ranks are arranged in the corresponding arrangement pattern rows.

  In the example shown in FIG. 12, in one light source substrate 213, the light emitting elements 212 of the first rank R1 (the upper light emitting elements in the drawing) are arranged in the first arrangement pattern row PT1, and the light emitting elements 212 of the second rank R2 are arranged. (The light emitting elements in the middle in the figure) are arranged in the second arrangement pattern row PT2, and the light emitting elements 212 (the light emitting elements in the lower stage in the drawing) in the third rank R3 are arranged in the third arrangement pattern row PT3.

  In the first embodiment, a part of the H-shaped arrangement pattern pt (here, the connecting portion ptc) is electrically connected by the connecting portion ptf between the adjacent arrangement pattern rows PT and PT in the sub-scanning direction Y. Yes. By doing so, as shown in FIG. 12, even if the light emitting elements having different luminance ranks are arranged in the corresponding arrangement pattern rows, it is possible to energize each of the light emitting elements 212,. Of the arrangement patterns pt, the arrangement patterns pt at both ends in the main scanning direction X are electrically connected to the first electrode wiring pattern ptd and the second electrode wiring pattern pte. The connection part ptf can be omitted. Further, as shown in FIGS. 9 to 11, when the light emitting elements 212,... Having the same luminance rank are arranged in a line in the corresponding arrangement pattern row, the connecting portion ptf may be omitted.

(Second Embodiment)
In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  In the second embodiment, as in the first embodiment, as shown in FIGS. 4, 6, and 7, the light source substrate 213 has the arrangement surface F in the main scanning direction X with respect to the light irradiation surface Gd of the document G. It arrange | positions so that it may incline around the axis line which followed.

  The light source substrate 213 may be arranged such that the arrangement surface F is perpendicular to or parallel to the light irradiation surface Gd of the document G. In this case, the light emitting element 212 is preferably arranged on the light source substrate 213 so that the direction of the optical axis L is inclined with respect to the arrangement surface F of the light source substrate 213 (toward the light irradiation region Ld side).

  FIG. 13 is a side view illustrating a schematic configuration of the light source substrate 213 of the second embodiment. In the second embodiment, as shown in FIG. 13A, as the light source substrate 213, a plurality of types of substrates 2131 to 213n having different thicknesses d1,..., Dn according to a plurality of luminance ranks R1,. Is predetermined.

  The light emitting elements 212,... Of each of the brightness ranks R1,..., Rn are arranged on a substrate having a thickness corresponding to each of the brightness ranks R1,.

  In the light source substrate 213 having such a configuration, for example, when the optical axis L is perpendicular to the arrangement surface F as in the case of performing top surface light emission as shown in FIG. Any one of a plurality of optical axis distances H1,..., Hn can be set and changed as the optical axis distance H while maintaining. That is, among the plurality of types of substrates 213, a substrate having a thickness in which any of the plurality of optical axis distances H1,..., Hn is set as the optical axis distance H based on any of the plurality of luminance ranks R1,. The light emitting elements 212 of the brightness rank can be arranged. When the optical axis L is not perpendicular to the arrangement surface F, at least the light irradiation position in the sub-scanning direction Y is changed among the optical axis distance H and the light irradiation position in the sub-scanning direction Y. be able to.

  For example, the plurality of luminance ranks R1,..., Rn are set from the first luminance rank R1 to the third luminance rank R3, and the first to third substrates 2131 to 2133 having different thicknesses d1 to d3 as the light source substrate 213 in advance. The case where it is prepared will be described below as an example. In this case, any one of the first to third optical axis distances H1 to H3 can be set and changed as the optical axis distance H according to the first to third luminance ranks R1 to R3.

  FIG. 13B shows a light source substrate 2131 having a first thickness d1 corresponding to the first luminance rank R1, and FIG. 13C shows a light source substrate having a second thickness d2 corresponding to the second luminance rank R2. FIG. 13D shows a light source substrate 2133 having a third thickness d3 corresponding to the third luminance rank R3.

  As shown in FIG. 13B, when the light emitting elements 212,... Having the darkest first luminance rank R1 are arranged on the light source substrate 2131 having the first thickness d1 (for example, 6 mm) corresponding to the first luminance rank R1. The optical axis distance H of the light emitting elements 212,... Is the first optical axis distance H1. Therefore, the illuminance on the light irradiation surface Gd of the original G by the light emitting elements 212,... Arranged on the light source substrate 2131 having the first thickness d1 (for example, 6 mm) is set to an appropriate illuminance, and uneven illuminance is less noticeable. it can.

  As shown in FIG. 13C, the light emitting elements 212 of the second luminance rank R2 having intermediate brightness are arranged on the light source substrate 2132 having the second thickness d2 (for example, 4 mm) corresponding to the second luminance rank R2. In this case, the optical axis distance H of the light emitting elements 212,... Is the second optical axis distance H2. Therefore, the illuminance on the light irradiation surface Gd of the original G by the light emitting elements 212,... Arranged on the light source substrate 2132 having the second thickness d2 (for example, 4 mm) is set to an appropriate illuminance, and uneven illuminance is less noticeable. it can.

  As shown in FIG. 13D, the brightest light emitting elements 212 of the third luminance rank R3 are arranged on the light source substrate 2133 having a third thickness d3 (for example, 2 mm) corresponding to the third luminance rank R3. Sometimes, the optical axis distance H of the light emitting elements 212,... Is the third optical axis distance H3. Therefore, the illuminance on the light irradiation surface Gd of the document G by the light emitting elements 212,... Arranged on the light source substrate 2132 having the third thickness d3 (for example, 2 mm) is set to an appropriate illuminance, and uneven illuminance is less noticeable. it can.

  The thickness of the light source substrate 213 varies depending on design parameters such as the arrangement configuration of the light source substrate 213 in the light source unit 210 and the luminance level of the light emitting element, and can be set as appropriate. In addition, the increment of the thickness of the light source substrate 213 may be constant between continuous luminance ranks, or may be an arbitrary value.

  Examples of the light source substrate 213 include substrates that are generally used such as a paper phenol substrate, a paper epoxy substrate, and a glass epoxy substrate. In addition, you may use the board | substrate which provided the insulating layer in the metal plate for heat dissipation, such as aluminum and copper. However, the present invention is not limited to this, and any of the light source substrates 213 can be selected as appropriate.

(About 1st Embodiment and 2nd Embodiment)
As described above, in the first embodiment and the second embodiment, for example, the light emitting elements 212,... Can be arranged based on the first to third luminance ranks R1 to R3. Even if the configuration of the light source unit 210 is not significantly changed, the optical axis distance H and the light irradiation position can be easily set only by arranging the light emitting elements 212,... On the light source substrate 213. For example, in the case of using the light emitting elements 212,... Having a lower luminance rank (specifically, the first luminance rank R1), in order to improve the illuminance on the light irradiation surface Gd of the document G as a whole, the light emitting element 212 is used. ,... Can be easily placed close to the original G and placed on the light source substrate 213. In addition, in the case where the light emitting elements 212,... Having a high luminance rank (specifically, the third luminance rank R3) are used, it is difficult to make the illuminance unevenness (bright spot) on the light irradiation surface Gd of the original G inconspicuous. The light emitting elements 212,... Can be easily moved away from the original G and placed on the light source substrate 213. Thereby, a commercially available light emitting element can be used over a wide range of luminance ranks.

  As described above, according to the first and second embodiments, it is possible to use a commercially available light emitting element over a wide range of luminance ranks without significantly changing the configuration of the light source unit 210, thereby reducing the cost. A light-emitting element that has been realized can be used.

  Moreover, in 1st Embodiment and 2nd Embodiment, the board | substrate which can set and change optical-axis distances H1-H3 and a light irradiation position based on brightness | luminance rank R1-R3 is used as the light source board | substrate 213. FIG. By using such a substrate, the optical axis distance H and the light irradiation position can be easily set by the substrate.

  In the first embodiment, the light emitting elements 212,... Can be arranged in any of the first to third arrangement pattern rows PT1 to PT3 according to the first to third luminance ranks R1 to R3. Thereby, the optical axis distance H and the light irradiation position can be easily set with a simple configuration.

  In the second embodiment, the light emitting elements 212,... Can be arranged on any of the first to third substrates 2131 to 2133 according to the first to third luminance ranks R1 to R3. Thereby, the optical axis distance H and the light irradiation position can be easily set with a simple configuration.

  In the first embodiment and the second embodiment, among the light emitting elements 212,..., The light emitting element 212 having a low luminance rank (for example, the first luminance rank R1) has a high luminance rank (for example, the third luminance rank). It is arranged closer to the original G than the light emitting element 212 (of R3). By doing so, the illuminance on the light irradiation surface Gd of the original G can be improved for the light emitting elements 212,... Having a low luminance rank (for example, the first luminance rank R1), and the luminance rank is increased ( For the light emitting elements 212,... Of the third luminance rank R3, for example, the illuminance unevenness in the main scanning direction X on the light irradiation surface Gd of the original G can be made inconspicuous.

  By the way, in 1st Embodiment and 2nd Embodiment, since the 1st light emitting element row | line | column 220a and the 2nd light emitting element row | line | column 220b are arranged on the both sides of the transversal direction of the slit R, as the light emitting element 212, ..., for example, Even if the light emitting element 212 having a lower luminance rank (specifically, the first luminance rank R1) is used in one light emitting element row 220a, the lower luminance of the light emitting element 212 is opposed to the light emitting element 212. It can be supplemented by the light emitting element 212 in the other light emitting element row 220b. This makes it possible to use a commercially available light emitting element over a wider range of luminance ranks.

  As described above, when the light emitting elements 212,... Are arranged in two rows of the first light emitting element row 220a and the second light emitting element row 220b, the light emitting elements 212,. 212 (first light-emitting element 212a and second light-emitting element 212b) are opposed to each other so that the degree of illuminance on the light irradiation surface Gd of the document G and the illuminance unevenness are inconspicuous based on the luminance of both the first light-emitting element 212a and the second light-emitting element 212b. The optical axis distance H of the light emitting elements 212 and 212 (the first light emitting element 212a and the second light emitting element 212b) may be set. For example, the optical axis distance H of the first and second light emitting elements 212a and 212b facing each other can be set as follows.

  FIG. 14 shows the first setting of the optical axis distance H of the first and second light emitting elements 212a and 212b in the case where the light emitting element arrays 220a along the main scanning direction X are arranged in two lines in the sub scanning direction Y. It is a figure which shows an example. FIG. 15 shows the optical axis distance H of the first and second light emitting elements 212a and 212b when the light emitting element arrays 220a and 220b along the main scanning direction X are arranged in two lines in the sub scanning direction Y. It is a figure which shows 2 setting examples. 14 and 15, members such as the light source substrate 213 are not shown.

  In the first setting example shown in FIG. 14, the first and second light emitting elements 212a and 212b facing each other between the first light emitting element array 220a and the second light emitting element array 220b have different luminance ranks. Thus, although the brightness ranks of the first and second light emitting elements 212a and 212b facing each other are different from each other, it is possible to secure a state in which the illuminance level and the illuminance unevenness on the light irradiation surface Gd of the document G are inconspicuous. If present, the optical axis distance H of the opposing first and second light emitting elements 212a and 212b may be the same length (H3 in the illustrated example).

  In the second setting example shown in FIG. 15, the first and second light emitting elements 212a and 212b facing each other between the first light emitting element array 220a and the second light emitting element array 220b have the same brightness rank. It has become. Thus, although the brightness ranks of the first and second light emitting elements 212a and 212b facing each other are the same rank, the degree of illuminance on the light irradiation surface Gd of the original G and the illuminance unevenness are inconspicuous. If possible, the optical axis distance H of the opposing first and second light emitting elements 212a and 212b may be different from each other (H1 <H3 in the illustrated example).

  In the first and second embodiments, the luminance ranks assigned to the first and second light emitting elements 212a and 212b may be the luminance ranks ranked by the respective manufacturers as they are. Re-ranking may be performed based on the brightness rank ranked by the manufacturer. For example, when using light emitting elements from different manufacturers, the brightness ranks for use in common may be re-ranked with respect to the brightness ranks ranked by each manufacturer. Further, a plurality of ranked (for example, two or three) brightness ranks may be combined into one rank and re-ranked.

  In the first embodiment and the second embodiment, the light source unit 210 is configured as follows in order to suppress the occurrence of shadows that tend to appear when reading the image of the document G placed on the document table glass 201a. be able to.

  FIG. 16 is an explanatory diagram for explaining a shadow SD that is likely to appear when an image of the document G placed on the platen glass 201a is read.

  The light source unit 210 shown in FIG. 16 has a configuration shown in FIG. 4 in which the first light emitting element row 220a and the second light emitting element row 220b are arranged on both sides of the slit R in the short direction. Then, when reading the image of the document G placed on the document table glass 201a, the shadow SD tends to appear at the upstream end of the document G in the direction toward the one side Y3 in the sub-scanning direction Y. The occurrence of the shadow SD is particularly noticeable when the original G is thick.

  From this point of view, in the first light emitting element array 220a and the second light emitting element array 220b, in the direction toward the one side Y3 in the sub-scanning direction Y, the upstream light emitting element array 220a is the upstream light emitting element array 220a. The illuminance on the light irradiation surface Gd of the original G is made larger than the illuminance on the light irradiation surface Gd of the original G by the light emitting element array 220b on the downstream side. As a result, it is possible to suppress the occurrence of a shadow SD that tends to appear when the image of the document G placed on the document table glass 201a is read.

  Here, as the light source unit 210 for suppressing the occurrence of the shadow SD, the light source unit having the configuration shown in FIG. 4 is illustrated here, but the first light emitting element row 220a and the second light emitting element row 220b are arranged. For example, the present invention may be applied to a light source unit having the configuration shown in FIG.

  Incidentally, since light emitting elements such as LEDs have strong directivity characteristics in a predetermined direction, unevenness in illuminance corresponding to the pitch of the light emitting elements 212,...

  For example, the illuminance unevenness of the light irradiation surface Gd of the original G becomes more conspicuous as the pitch of the light emitting elements 212,. For this reason, although it is preferable to make the said pitch small, when the said pitch is made small, the number of required light emitting elements will increase, and it will cause a cost increase.

  Also, as the optical axis distance H of the light emitting elements 212,. For this reason, it is preferable to increase the optical axis distance H. However, if the optical axis distance H is increased, the illuminance on the light irradiation surface Gd of the original G decreases, so the light amount of the light emitting element needs to be increased accordingly. .

  Therefore, the light emitting elements 212,... Are efficiently irradiated with the light from the light emitting elements 212,... In the state where the illuminance unevenness on the light irradiation surface Gd of the original G is reduced. It is preferable that the relationship between the pitch of 212,... And the optical axis distance of the light emitting elements 212,.

  Therefore, the light source unit 210 of the first embodiment and the second embodiment is configured as follows.

  FIG. 17 is a diagram for explaining unevenness [%] M and unevenness distance [mm] N on the light irradiation surface Gd of the original G by the first light emitting elements 212a,... And the second light emitting elements 212b,. FIG. 6 is a diagram showing light and dark repetitions in an illuminance cycle T in the main scanning direction X.

  In this illuminance cycle T, the unevenness [%] M is the average (median) illuminance value L3 [lx] obtained by subtracting the minimum illuminance value L2 [lx] from the maximum illuminance value L1 [lx (lux)]. Divided by ((L1-L2) / L3 [%]), and the non-uniformity distance [mm] N is a half cycle T / 2 of the illumination cycle T. When the amplitude [%] is K, the amplitude [%] K is obtained by dividing a value obtained by subtracting the average illuminance value L3 [lx] from the maximum illuminance value L1 [lx] by the average illuminance value L3 [lx]. ((L1-L3) / L3 [%]).

  A light emitting element pitch P (hereinafter referred to as LED pitch P) [mm] and an optical axis distance H [mm] that is a distance of the optical axis L from the light emitting element to the light irradiation region Ld of the document G are M ≦ It is set so as to satisfy the relationship of N / 2−5.5, more preferably the relationship of M ≦ N / 2−7.5.

  Next, the illuminance unevenness determination evaluation from which these relationships are derived will be described below.

[Illuminance unevenness evaluation]
In the illuminance unevenness evaluation, 19 patterns of images in which the values of the illuminance period T and the amplitude [%] K were changed based on a sine curve as shown in FIG. Here, the image was created using a personal computer and printed using a printer. The color tone of the printed image was gray.

  The various printed images created in this manner were visually confirmed by a large number of subjects, and it was determined whether density unevenness (density unevenness corresponding to illumination unevenness) on the printed image was acceptable. The determination results are shown in FIGS.

  FIG. 18 is a table showing a list of the illumination cycle T, the amplitude [%] K, the unevenness distance [mm] N and the unevenness [%] M calculated from these values, and the determination result of the printed image. FIG. 19 is a graph created based on the values shown in FIG. 18 with the unevenness [%] M as the vertical axis and the unevenness distance [mm] N as the horizontal axis.

  In the determination column of FIG. 18 and the graph of FIG. 19, “◯” indicates “determination that can sufficiently allow density unevenness (illuminance unevenness)”, and “Δ” indicates “determination of a limit that can allow density unevenness (illuminance unevenness). "And" x "indicate" determination that density unevenness (illuminance unevenness) cannot be tolerated ".

  As shown in FIG. 19, a determination (“x” determination) in which density unevenness (illuminance unevenness) is not allowed is made in a range of N / 2−5.5 (see β in the figure) <M, and N / 2− 7.5 (refer to γ in the figure) <M ≦ N / 2−5.5 (see rough shading in the figure), a limit determination (“Δ” determination) that can permit density unevenness (illuminance unevenness) is made. Thus, a determination (“◯” determination) in which density unevenness (illuminance unevenness) is sufficiently allowed is made in a range of M ≦ N / 2−7.5 (see fine shading in the drawing).

  Accordingly, the LED pitch P and the optical axis distance H are set so as to satisfy the relationship of N / 2−7.5 <M ≦ N / 2−5.5. Irradiance unevenness can be suppressed to an acceptable level, and by setting so as to satisfy the relationship of M ≦ N / 2−7.5, uneven illumination on the light irradiation surface Gd of the document G can be effectively prevented. Moreover, it can be used for general purposes.

  In this state, the relationship between the light emitting element pitch P and the optical axis distance H can be optimized so that the light from the light emitting element is efficiently irradiated onto the light irradiation surface Gd of the original G. For example, the value of the light emitting element pitch P can be set so that the number of light emitting elements is as small as possible with respect to the optical axis distance H, or the light irradiation surface Gd of the original G with respect to the light emitting element pitch P can be set. Can be set to a value of the optical axis distance H at which the illuminance of becomes as large as possible.

  Next, an analysis simulation for analyzing the unevenness [%] M and the unevenness distance [mm] N and specifying the range of (LED pitch P) / (optical axis distance H) will be described below.

[Analysis simulation]
In the analysis simulation, a virtual image reading device is realized on a computer using analysis simulation software (Light Tools (registered trademark) manufactured by Optical Research Associates), and an LED pitch P (4 mm to 24 mm) and an optical axis distance H ( The values of 4 mm to 19 mm) are variously changed to analyze the unevenness [%] M and the distance between unevenness [mm] N. FIG. 19 shows the unevenness [%] M and the distance between unevenness [mm] N thus analyzed. The value of P / H was determined based on the determination criteria shown in FIG.

  It should be noted that when several values of the LED pitch P and the optical axis distance H used in the analysis simulation were set and confirmed by an actual image reading apparatus, the unevenness [%] M and almost the same as the analysis simulation were confirmed. A non-uniformity distance [mm] N was obtained. From this, it was confirmed that the virtual image reading apparatus realized on the computer using the analysis simulation software is almost equivalent to the actual image reading apparatus.

  FIG. 20 is a diagram for explaining the conditions of the analysis simulation. In this analysis simulation, as shown in FIG. 20, the light source 211 has a single-row configuration in which 20 LED elements 212 having a light-emitting surface E2 that emits top light are arranged in a line, and the optical axis L is a document. It was arranged so as to be perpendicular to the G light irradiation surface Gd. The single (one) luminous flux of the LED element 212 was 7.81 [lm (lumen)] (luminous intensity 1900 [mcd (millicandela)]).

  21 to 23, the light irradiation surface Gd of the original G with respect to the distance [mm] in the main scanning direction at a partial value of the optical axis distance H in a partial value of the LED pitch P used in the analysis simulation. It is the graph which illustrated illumination intensity [lx] in. FIGS. 21A and 21B show graphs in which the LED pitch P is 8 mm and 10 mm, respectively. FIGS. 22A and 22B show the LED pitch P of 12 mm and 14 mm, respectively. FIG. 23A and FIG. 23B show graphs in which the LED pitch P is 16 mm and 18 mm, respectively. In each graph from FIG. 21 to FIG. 23, the optical axis distance H is exemplified as 6 mm, 8 mm, 10 mm, 12 mm, 14 mm, 16 mm, and 18 mm. The other graphs are not shown.

  Of these, an example of automatically determining illuminance unevenness with an optical axis distance H of 6 mm will be described below using the graph of FIG. 23A in which the LED pitch P is 16 mm.

  FIG. 24 is a diagram for explaining unevenness [%] M in the case where a light emitting element having a single-row configuration is used with the LED pitch P being 16 mm and the optical axis distance H being 6 mm.

  When the LED pitch P is 16 mm and the optical axis distance H is 6 mm, the maximum value L1 of the illuminance on the light irradiation surface Gd of the original G is 40000 [lx], and the minimum value L2 is 20000 [lx] from the graph of FIG. The average value L3 is 30000 [lx]. By substituting these values into the formula (L1-L2) / L3 of the unevenness [%] M described in FIG. 17, the unevenness [%] M becomes 66.7 [%]. Further, since the LED pitch P is 16 mm, the distance between unevenness [mm] N is 8 mm.

  The unevenness [%] M = 66.7 [%] and the unevenness distance [mm] N = 8 mm obtained in this way indicate the relationship between the unevenness [%] M and the unevenness distance [mm] N shown in FIG. When applied to the graph, N / 2−5.5 (see β in the figure) <M. Therefore, P / H (16 mm / 6 mm = 2.67) is determined as a determination that the unevenness in illuminance cannot be tolerated (x determination). The results obtained in the same manner for other values in this way are shown in the tables in FIGS.

  FIG. 25 shows the determination result of P / H when the LED pitch P is a value in 1 mm increments of 4 mm to 11 mm and the optical axis distance H is a value in 1 mm increments of 4 mm to 24 mm. FIG. 26 shows the determination result of P / H when the LED pitch P is a value in 1 mm increments from 12 mm to 19 mm and the optical axis distance H is a value in 1 mm increments from 4 mm to 24 mm.

  As shown in FIGS. 25 and 26, when satisfying the relationship of P / H> 0.83, it is determined that the illuminance unevenness cannot be allowed (x determination), and the relationship of 0.71 <P / H ≦ 0.83 is satisfied. When it satisfies, it is determined as a limit determination (Δ determination) that can allow illuminance unevenness, and when it satisfies the relationship of P / H ≦ 0.71, it is determined as a determination that can sufficiently allow illuminance unevenness (◯ determination).

  From the above, it was found that the illuminance unevenness can be suppressed when the light emitting element pitch P and the optical axis distance H satisfy the relationship of P / H ≦ 0.83. Thus, in setting the light emitting element pitch P and the optical axis distance H, it is only necessary to substitute the light emitting element pitch P or the optical axis distance H into the relational expression of P / H ≦ 0.83, so that M ≦ N / 2. One of the light emitting element pitch P and the optical axis distance H can be easily set so as to satisfy the relationship of −5.5. For example, when the optical axis distance H is calculated by substituting the light emitting element pitch P, the optical axis distance H is (P / 0.83) from the viewpoint of increasing the illuminance on the light irradiation surface Gd of the original G as much as possible. ) Value or (P / 0.83) or more and as close as possible to the value. On the other hand, when the light-emitting element pitch P is obtained by substituting the optical axis distance H, the light-emitting element pitch P is a value of (H × 0.83) or (H × 0.83) or less and as close to the value as possible.

  Further, it has been found that when the light emitting element pitch P and the optical axis distance H satisfy the relationship of P / H ≦ 0.71, illuminance unevenness can be effectively prevented. Thus, in setting the light emitting element pitch P and the optical axis distance H, it is only necessary to substitute the light emitting element pitch P or the optical axis distance H into the relational expression of P / H ≦ 0.71, so that M ≦ N / 2. One of the light emitting element pitch P and the optical axis distance H can be easily set so as to satisfy the relationship of −7.5. For example, when the optical axis distance H is obtained by substituting the light emitting element pitch P, the optical axis distance H is (P / 0.71) from the viewpoint of increasing the illuminance on the light irradiation surface Gd of the original G as much as possible. ) Value or (P / 0.71) or more and as close as possible to the value. On the other hand, when the light-emitting element pitch P is calculated by substituting the optical axis distance H, the light-emitting element pitch P is a value of (H × 0.71) or (H X0.71) or less and as close as possible to the value.

  Note that the analysis simulation here was performed for a light emitting element having a single-row configuration as shown in FIG. 20. However, the light emitting element arrangement configuration that can form unevenness [%] M and uneven distance [mm] N is possible. Any one can be applied.

  Further, even if the analysis simulation is performed as a light emitting element having the same pitch position configuration as shown in FIG. 5 (the illuminance is twice that of the single row configuration), the simulation result does not change.

  FIG. 27 uses the light emitting element having the same pitch position configuration shown in FIG. 5 (the illuminance is twice that of the single-row configuration) shown in FIG. 5 under the conditions of FIG. It is a figure for demonstrating the nonuniformity [%] M in a case.

  As shown in FIG. 27, in the light emitting elements having the same pitch position configuration, the maximum illuminance value L1 on the light irradiation surface Gd of the document G is 80000 [lx], the minimum value L2 is 40000 [lx], and the average value L3 is 60000. [Lx]. By substituting these values into the formula (L1-L2) / L3 of the unevenness [%] M described in FIG. 17, the unevenness [%] M becomes 66.7 [%].

  Thus, even if the light emitting elements having the same pitch position configuration shown in FIG. 5 are used, the same unevenness [%] M as that of the light emitting elements having the single row configuration shown in FIG. Therefore, even if the analysis simulation is performed as a light emitting element having the same pitch position configuration as shown in FIG.

  In the analysis simulation, the single (one) luminous flux of the LED element 212 is set at 7.81 [lm] (luminous intensity 1900 [mcd]). Even in the case, the unevenness M (%) has the same result for the same reason as described above.

  In other words, regardless of the arrangement configuration of the light-emitting elements and the light amount, if P / H ≦ 0.83 is satisfied, it is possible to suppress uneven illuminance to a level that can withstand practical use, and P / H ≦ 0. If 71 is satisfied, illuminance unevenness can be effectively prevented.

  In the image reading apparatus 100 shown in FIGS. 1 and 2, the light source 211 can directly irradiate the original G through the original tables 201a and 201b. Therefore, the illuminance unevenness can be suppressed without providing a diffusing member that is provided between the original and the light source in the conventional illumination device, so that the manufacturing cost does not increase and the light from the light source 211 is not emitted. It is possible to avoid a loss of light amount when irradiating the original G, and for example, it can be applied to an image reading apparatus having a relatively high reading speed of the original G without increasing the light amount of the light emitting element. .

100 Image Reading Apparatus 201a Document Placement Table (Original Plate Glass)
210 Light source unit (an example of a lighting device)
212 Light-emitting element 212a First light-emitting element 212b Second light-emitting element 213 Light source substrate (an example of a substrate)
2131,..., 213n Light source substrate (an example of a substrate)
220a 1st light emitting element row | line | column 220b 2nd light emitting element row | line | column d1, ..., dn Thickness D Image forming apparatus G Manuscript (an example of to-be-irradiated body)
Gd Light irradiation surface H Optical axis distance P Light emitting element pitch PT1,..., PTn Arrangement pattern row pt11, ..., ptmn Arrangement pattern R Slit R1, ..., Rn Luminance rank X Main scanning direction Y Sub-scanning direction Y3 Sub-scanning direction Y One side

Claims (10)

An illumination device that irradiates light from a plurality of light emitting elements arranged on a substrate toward a light irradiation surface of an irradiated object,
The plurality of light emitting elements are ranked in a plurality of luminance ranks set in advance with respect to the luminance of light to be emitted,
Based on the brightness rank, the light emitting element can be arranged so that at least one of an optical axis distance to the irradiated object and a light irradiation position in a direction intersecting with the arrangement direction of the light emitting elements can be set. It is assumed that
The substrate is configured to be able to arrange the light emitting element based on the luminance rank,
The substrate is formed with a plurality of arrangement pattern rows arranged along the arrangement direction of the light emitting elements along a direction intersecting the arrangement direction for arranging the light emitting elements. ,
Among the plurality of arrangement pattern sequences, a lighting device having the luminance rank is arranged in an arrangement pattern sequence set based on the luminance rank . An illumination device that irradiates light from a plurality of light emitting elements arranged on a substrate toward a light irradiation surface of an irradiated object,
The plurality of light emitting elements are ranked in a plurality of luminance ranks set in advance with respect to the luminance of light to be emitted,
Based on the brightness rank, the light emitting element can be arranged so that at least one of an optical axis distance to the irradiated object and a light irradiation position in a direction intersecting with the arrangement direction of the light emitting elements can be set. It is assumed that
The substrate is configured to be able to arrange the light emitting element based on the luminance rank ,
A lighting device , wherein a light emitting element having a luminance rank is arranged on a substrate having a thickness set based on the luminance rank among a plurality of types of substrates having different thicknesses . The lighting device according to claim 1 or 2 ,
Of the plurality of light emitting elements, the light emitting element having a low luminance rank is disposed closer to the irradiated body than the light emitting element having a high luminance rank. It is an illuminating device as described in any one of Claim 1- Claim 3 , Comprising:
The plurality of light emitting elements are arranged along a slit for allowing reflected light from the irradiated object to pass therethrough, and are arranged on one side in the short direction of the slit with respect to the slit. A first light-emitting element array composed of a plurality of first light-emitting elements, and a second light-emitting element array composed of a plurality of second light-emitting elements arranged in the other side in the short direction of the slit. A lighting device characterized by the above. The lighting device according to claim 4 ,
Provided in an image reading apparatus that scans an image of a document placed on a document placement table in the main scanning direction and the sub-scanning direction using the irradiated body as a document,
The slit is disposed along the main scanning direction,
The illumination device is a scanning device that moves to one side in the sub-scanning direction with respect to the document placed on the document placement table when reading an image of the document,
Of the first light-emitting element array and the second light-emitting element array, the upstream light-emitting element array is a light irradiation surface of a document by the upstream light-emitting element array in the direction toward one side in the sub-scanning direction. Is set to be larger than the illuminance on the light irradiation surface of the document by the light emitting element array on the downstream side. It is an illuminating device as described in any one of Claim 1- Claim 5 , Comprising:
When the light emitting element pitch in the arrangement direction of the plurality of light emitting elements is P, and the optical axis distance to the irradiated body of the plurality of light emitting elements is H,
The light emitting element pitch P and the optical axis distance H are:
P / H ≦ 0.83
An illumination device characterized by satisfying the relationship: The lighting device according to claim 6 ,
The light emitting element pitch P and the optical axis distance H are:
P / H ≦ 0.71
An illumination device characterized by satisfying the relationship: An image reading apparatus comprising the illumination device according to any one of claims 1 to 7 . An image forming apparatus comprising the image reading apparatus according to claim 8 . A substrate provided in the lighting device according to claim 1 ,
A plurality of arrangement pattern rows in which arrangement patterns for arranging the light emitting elements are arranged along the arrangement direction of the light emitting elements are formed along a direction intersecting the arrangement direction. substrate.

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