Patent Publication Number: US-2007109395-A1

Title: Led array head and image recording device

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
      This application claims priority under 35 USC 119 from Japanese Patent Application No. 2005-330305, the disclosure of which is incorporated by reference herein.  
     BACKGROUND  
      1. Technical Field  
      The present invention relates to an LED array head having plural LEDs, and to an image recording device.  
      2. Related Art  
      Conventionally, an LED array, which is used in an LED array head or the like as a light-emitting device, and a printed board are connected by bonding wires. At the portions where the bonding wires are joined on the LED array, the light from the light-emitting points of the LEDs is reflected by the balls or the wires or the like of the bonding wires, and it is easy for scattered light and stray light to arise.  
      Because photoreceptors are exposed by this scattered light or stray light at exposure amounts which are greater than or equal to their original exposure amounts, a problem arises in that image stripes are formed and the image quality deteriorates.  
     SUMMARY  
      In consideration of the above circumstances, the present invention provides an LED array head and an image recording device.  
      A first aspect of the present invention is an LED array head including: LED arrays at which plural LEDs are positioned; a substrate on which the LED arrays are staggered; first electrode pads provided at end portions of the LED arrays and positioned facing LEDs of adjacent LED arrays; second electrode pads provided on the substrate at a side opposite the adjacent LED arrays and connected to the first electrode pads electrically by wires; and light-blocking elements that block light, which is emitted from the LEDs of the adjacent LED arrays, from reaching the wires. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      Embodiments of the present invention will be described in detail based on the following figures, wherein:  
       FIG. 1  is a schematic structural diagram showing the structure of an image recording device to which an LED array head relating to an exemplary embodiment of the present invention is applied;  
       FIG. 2  is a perspective view explaining the relationship between a photoreceptor and the LED array head relating to the exemplary embodiment of the present invention;  
       FIG. 3  is a plan view showing the LED array head relating to the exemplary embodiment of the present invention;  
       FIG. 4  is a cross-sectional view showing a state in which a bonding wire of an LED array relating to the exemplary embodiment of the present invention is covered by a light-blocking insulator;  
       FIG. 5A  is a schematic diagram showing a state in which stray light due to light from light-emitting points of LEDs arises, and  FIG. 5B  is a schematic diagram corresponding to  FIG. 5A  and showing results of an example;  
       FIG. 6  is a cross-sectional view showing a state in which the LED array relating to the exemplary embodiment of the present invention is bonded by BSOB;  
       FIG. 7A  is an explanatory diagram showing a shape of a bonding wire in accordance with standard bonding,  FIG. 7B  is an explanatory diagram showing a shape of a bonding wire in accordance with BSOB,  FIG. 7C  is an explanatory diagram showing a shape of a bonding wire in accordance with an ultra-low loop, and  FIG. 7D  is an explanatory diagram showing a shape of a bonding wire in accordance with STCB;  
       FIG. 8B  is an enlarged plan view showing the LED array head, and  FIG. 8A  is a side view showing the shapes of respective bonding wires at positions corresponding to  FIG. 8B ;  
       FIG. 9  is a cross-sectional view showing an example in which a light-blocking wall is provided between bonding wires of the LED array relating to the exemplary embodiment of the present invention and LEDs of an adjacent LED array;  
       FIG. 10  is a cross-sectional view showing an example in which the heights of LED arrays relating to the exemplary embodiment of the present invention are changed;  
       FIG. 11  is a cross-sectional view showing another example in which the heights of LED arrays relating to the exemplary embodiment of the present invention are changed; and  
       FIG. 12  is a cross-sectional view showing a comparative example of  FIG. 4 . 
    
    
     DETAILED DESCRIPTION  
      An image recording device  10 , to which an LED array head  20  relating to an exemplary embodiment of the present invention is applied, is shown in  FIG. 1 . The image recording device  10  is a so-called tandem-type image recording device. The image recording device  10  has an intermediate transfer belt  12  which spans substantially horizontally. Four image recording sections  14 , which correspond to respectively different developing colors, are disposed beneath the intermediate transfer belt  12 .  
      A sheet tray  11  is provided beneath the image recording sections  14 . A conveying path  13 , which extends upward from the sheet feeding side of the sheet tray  11 , passes through a secondary transfer section  15  which contacts the intermediate transfer belt  12 , and a fixing section  17  which has a fixing device, and reaches a discharge opening. The outer side of the discharge opening is a sheet discharge tray  19 .  
      Each of the image recording sections  14  has a photoreceptor  16 , a charger  18 , an LED array head  20 , a developing device  40 , and a cleaner  42 .  
      The photoreceptor  16  is shaped as a cylindrical tube, and the outer peripheral surface thereof is a light-receiving surface  16 A. An electrostatic latent image can be formed on the light-receiving surface  16 A. The light-receiving surface  16 A contacts the intermediate transfer belt at the downstream side, in the direction of rotation of the photoreceptor (the direction of arrow R), of the developing device  40  (hereinafter simply called “downstream side”).  
      The charger  18  is an electrically conductive roller. The core of the charger  18  is formed of metal, and is covered by an elastic layer made of a synthetic resin. Negative-polarity voltage is applied by a power source (not shown). The LED array head  20  is disposed at the downstream side of the charger  18 . The LED array head  20  irradiates a light-image onto the light-receiving surface  16 A (photosensitive surface) of the photoreceptor  16 . In this way, the photoreceptor  16 , which is charged by the charger  18 , is exposed, and an electrostatic latent image is formed thereon.  
      The developing device  40  is disposed at the downstream side of the LED array head  20 . A two-component developing agent, in which a toner and a carrier are mixed together, is filled in the developing device  40 . The toner and the carrier filled in the developing device  40  are stirred, frictionally-charged, and mixed together uniformly. The toner is thereby electrostatically attracted to the carrier.  
      The carrier, which is a magnetic powder, is attracted by the magnetic force of a magnet roller  44  which is disposed so as to oppose the photoreceptor  16 . The toner, which adheres to the carrier on the magnet roller  44 , electrostatically adheres to the photoreceptor  16  due to the potential difference (the developing potential) between the potential (—200 V) at which the photoreceptor  16  is exposed and the developing bias potential (—550 V).  
      In this way, the developing device  40  causes the toner to adhere to and develop the electrostatic latent image formed on the photoreceptor  16 , so as to form a toner image. Then, the toner image is transferred onto the intermediate transfer belt  12 , and the toner images of all of the colors are ultimately superposed one on top of another on the intermediate transfer belt  12 .  
      On the other hand, the cleaner  42 , which is disposed at the downstream side of the developing device  40 , abuts the light-receiving surface  16 A of the photoreceptor  16  and removes adhering matter (waste toner, waste carrier, and the like) which adheres to the photoreceptor  16 .  
      The LED array head relating to the first exemplary embodiment of the present invention will be described.  
      As shown in  FIG. 2 , the LED array head  20  has an elongated printed board  22 . Circuits, which are for supplying various types of signals which control the driving of the LED array head  20  (respective LEDs  28 ), are formed on the printed board  22 . Image data of an amount corresponding to one line can be processed successively.  
      LED arrays (also called LED chips)  26 ,  27  are lined-up in a staggered manner, adjacent to one another on the printed board  22  such that longitudinal direction end portions thereof partially overlap one another. The plural LEDs  28 , which are lined-up one-dimensionally along the longitudinal direction of the LED arrays  26 ,  27 , are provided on the top surfaces of the LED arrays  26 ,  27 . The LEDs  28  of a number which is the number of pixels (number of dots) corresponding to the resolution are provided.  
      On the other hand, a lens holder  23  is provided at a position opposing the printed board  22 . Rod lens arrays (SLAs)  30  serving as collecting lenses (an optical system) are lined-up along the same direction as the longitudinal direction of the printed board  22 . The light from the LEDs  28  of the LED arrays  26 ,  27  is imaged onto the photoreceptor  16  by the rod lens arrays  30 .  
      Here, in the present exemplary embodiment, self-scanning LED (SLED) arrays are used as the LED arrays  26 ,  27 . An SLED array can selectively make the on/off timing of a switch emit light in accordance with two signal wires. Therefore, the data wire can be used in common, and the wiring can be simplified. The structure disclosed in Japanese Patent Application Laid-Open (JP-A) No. 8-216448, for example, can be used as the SLED array.  
      With these self-scanning LEDs, the number of first electrode pads  32  (see  FIG. 3 ), which electrically connect the LED arrays  26 ,  27  to the printed board  22 , can be greatly reduced as compared with a conventional LED array. Therefore, the first electrode pads  32  can be concentrated at the end portions, in the direction in which the LEDs  28  are lined-up, of the LED arrays  26 ,  27 .  
      Accordingly, as shown in  FIG. 3 , the first electrode pads  32  are disposed at the longitudinal direction both end sides of the LED arrays  26 ,  27 . Second electrode pads  24  are disposed on the printed board  22  at positions corresponding to the first electrode pads  32 . The first electrode pads  32  and the second electrode pads  24  are connected by bonding wires  34  which are formed from metal wires.  
      By making the number of first electrode pads  32  much smaller than in a conventional LED array, the LED arrays  26 ,  27  can be made to be more compact. Therefore, the number of chips procured from one wafer can be greatly increased, and the cost per chip can be decreased.  
      There are no LEDs  28  at the positions where the first electrode pads  32  are disposed. Therefore, in order to carry out exposure without gaps along the axial direction of the photoreceptor  16  (see  FIG. 1 ), the portions where the first electrode pads  32  are disposed at the LED array  27  (or at the LED array  26 ) are disposed so as to oppose the LEDs  28  of the adjacent LED array  26  (or LED array  27 ).  
      Thus, the first electrode pads  32  of the LED array  27  are disposed at positions in vicinities of the LEDs  28  of the adjacent LED array  26 . In the case of  FIG. 12 , at the portion where a bonding wire  35  is joined to the first electrode pad  32  on the LED array  27 , light from the light-emitting points of the LEDs  28  of the LED array  26  is reflected by a wire  35 A or the like of the bonding wire  35 , and it is easy for scattered light or stray light to arise. (Note that same holds for the LED array  27  with respect to the first electrode pads  32  of the LED array  26 , but, for convenience, only the LED array  27  side is explained.)  
      Accordingly, in the present exemplary embodiment, as shown in  FIG. 4 , a wire  34 A and a ball portion  34 B at the first electrode pad  32  side of the bonding wire  34  are covered by a light-blocking insulator  50 . Here, a silicon or epoxy material is used for the light-blocking insulator  50 , and a blackish color which is difficult to reflect the light of the LEDs  28  is used for the light-blocking insulator  50 . Further, the light-blocking insulator  50  is made to be matte which is difficult to regularly reflect the light of the LEDs  28 .  
      By covering the wire  34 A and the ball portion  34 B at the first electrode pad  32  side of the bonding wire  34  with the light-blocking insulator  50 , the light from the light-emitting points of the LEDs  28  which are disposed at the adjacent LED array  26  is blocked. Therefore, light is not reflected by the wire  34 A at the interior of the light-blocking insulator  50 , and the occurrence of scattered light and stray light can be prevented.  
      Here,  FIGS. 5A and 5B  schematically show experimental results, photographed through a CCD, of light which is emitted from the LEDs  28  and passes through the rod lens arrays  30 . In the comparative example, as shown in  FIG. 5A , stray light (the points shaped like white ovals) arises. In contrast, in the example of the present exemplary embodiment, as shown in  FIG. 5B , stray light does not arise.  
      The generating of stray light can be prevented by covering the first electrode pad  32  side of the bonding wire  34  by the light-blocking insulator  50 . Therefore, it suffices to not carry out STCB (so-called stitch bonding which will be described later) at the first electrode pad  32  as a countermeasure to stray light.  
      Thus, the pad strength (so-called pull strength) of the first electrode pad  32  on the LED array  27  can be lowered, and the size of the first electrode pad  32  can be made smaller. Moreover, because stray light does not arise even though the first electrode pad  32  is small, the LED arrays  26 ,  27  which are compact can be manufactured, and it is possible to make the image recording device  10  compact.  
      Concretely, the dimension, in the shorter-side direction, of the LED arrays  26 ,  27  can be made to be less than or equal to 130 μm. (The size is generally 300 μm.)  
      Further, the first run rate of production is improved because it suffices to not carry out stitch bonding on the first electrode pad  32  as a countermeasure to stray light. Namely, because the force of bonding to the first electrode pad  32  can be made to be small, there is less damage such as cracking and the like to the LED arrays  26 ,  27 , and an improvement in the yield of the manufactured product can be anticipated.  
      Here, the wire  34 A and the ball portion  34 B at the first electrode pad  32  side of the bonding wire  34  are covered by the light-blocking insulator  50 , such that the light from the light-emitting points of the LEDs  28  disposed at the adjacent LED array  26  is blocked. However, the present invention is not limited to the same because it suffices to be able to prevent stray light.  
      For example, as shown in  FIG. 6 , the following may be carried out. After producing a ball on the first electrode pad  32 , a bonding wire  52  is bonded to the second electrode pad  24  (first bonding), and bonding onto the ball on the first electrode pad  32  is carried out (second bonding). In this way, the ball on the first electrode pad  32  is crushed (so-called BSOB (Bond Stitch on Ball)). The first electrode pad  32  and the second electrode pad  24  are thereby connected electrically. Namely, no ball portion is formed on the first electrode pad  32 , and the bonding wire  52  is connected by a low loop.  
      In this way, the light from the light-emitting points of the LEDs  28  can be made to not reach the bonding wire  52 , by connecting the bonding wire  52  by a low loop (H 2 &lt;H 1 ) and making the height of the bonding wire  52  be outside of the light-emitting region of the LEDs  28  disposed at the adjacent LED array  26  (the region shown by the so-called directional angle θ (the spread angle of the light with respect to the optical axis of the LED)). Note that, other than BSOB, an FJ loop (a bonding method by Kaijo Corporation) which is a so-called ultra-low loop also can be applied.  
      The bonding wire  34  in accordance with standard bonding is shown in  FIG. 7A , the bonding wire  52  in accordance with BSOB is shown in  FIG. 7B , a bonding wire  54  in accordance with an ultra-low loop is shown in  FIG. 7C , and a bonding wire  56  in accordance with STCB (stitch bonding) is shown in  FIG. 7D .  
       FIG. 8B  is an enlarged diagram of the LED arrays  26 ,  27 . A side view of bonding wires connected to the LED array  26  is shown in  FIG. 8A . The bonding wire  34  by standard bonding is shown by the solid line, the bonding wire  52  by BSOB is shown by the one-dot chain line, the bonding wire  54  by an ultra-low loop is shown by the dotted line, and the bonding wire  56  by STCB is shown by the fine dotted line. As can be understood from this figure, the loop heights becomes lower in the order of standard bonding, ultra-low loop, BSOB, and STCB.  
      Here, with standard bonding (see  FIG. 7A ), if an attempt is made to lower the loop height, problems arise in that the neck (the base) of the ball portion  34 B is damaged and becomes easy to break, and the like. Therefore, the bonding specifications must be changed. Further, when the loop height is lowered, the bonding diameter of the ball portion  34 B must be made to be small, or the thickness of the ball portion  34 B must be made to be thin, and problems arise in terms of strength.  
      Therefore, a method which does not form the ball portion  34 B is desirably used at the first electrode pad  32  side. Accordingly, BSOB (see  FIG. 7B ), an ultra-low loop (see  FIG. 7C ), and STCB (see  FIG. 7D ) are suitable.  
      With BSOB, the loop can be made sufficiently low, and the pull strength can be ensured sufficiently. Further, an FJ loop eliminates the concern with regard to neck strength. The loop height of an FJ loop is slightly higher than that with BSOB. However, with an FJ loop, the electrode pad can be made even smaller than with BSOB, without changing the bonding specifications.  
      On the other hand, with STCB, the loop height of the bonding wire  56  is the lowest, and the problem of stray light does not arise. However, because STCB requires a large pad surface area, the widths of the LED arrays  26 ,  27  become large. Therefore, in a case in which the widths of the LED arrays  26 ,  27  are only about 125 μm, the pad surface area is small, and there is the concern that the pad may break at the time of bonding.  
      Accordingly, by not carrying out STCB at the first electrode pads  32  as a countermeasure to stray light, the pad strength of the first electrode pads  32  on the LED arrays  26 ,  27  can be made to be low, and the size of the first electrode pads  32  can be made to be small.  
      Namely, by using BSOB or an ultra-low loop as the method of bonding for electrically connecting the first electrode pads  32  and the second electrode pads  24 , stray light from the light-emitting points of the LEDs  28  disposed at the adjacent LED array  26  can be prevented, and the LED arrays  26 ,  27  which are compact can be manufactured.  
      Further, BSOB or an ultra-low loop may be used as the method of bonding for electrically connecting the first electrode pads  32  and the second electrode pads  24 , and further, the connected first electrode pad  32  sides at the bonding wires  52  or the bonding wires  54  may be covered by the light-blocking insulators  50 .  
      An LED array head relating to a second exemplary embodiment of the present invention will be described next.  
      As shown in  FIG. 9 , the following structure may be employed: by disposing a light-blocking wall  60 , which is formed of a silicon or epoxy material, between the LED arrays  26 ,  27  which are disposed adjacent to one another, the light-blocking wall  60  blocks the light from the light-emitting points of the LEDs  28  on the adjacent LED array  26 , and the light does not reach the bonding wires  34 .  
      Further, because it suffices for the light from the light-emitting points of the LEDs  28  on the adjacent LED array  26  to not reach the bonding wires  34 , the present invention is not limited to the same, and the light-blocking wall may be provided in a vicinity of the first electrode pads  32  on the LED array  27 .  
      Further, the present invention is not limited to a light-blocking wall, and the following structure shown in  FIG. 10  may be employed: by making the top surfaces of the LEDs  28  disposed at the adjacent LED array  26  lower than the top surfaces of the first electrode pads  32 , the light from the light-emitting points of the LEDs  28  disposed at the adjacent LED array  26  is blocked by a side wall  27 A of the LED array  27  at which the first electrode pads  32  are disposed. The light from the light-emitting points of these LEDs  28  does not reach the bonding wires  34 .  
      Further, the following structure shown in  FIG. 11  may be employed: by making the top surfaces of the LEDs  28  disposed at the adjacent LED array  26  higher than the top surfaces of the first electrode pads  32 , the bonding wires  34  are outside of the light-emitting region of these LEDs  28  (the region shown by the directional angle θ). The light from the light-emitting points of the LEDs  28  does not reach the bonding wires  34 .  
      In addition, the first electrode pad  32  sides of the bonding wires  34  may be covered by the light-blocking insulators  50 . In this case, not only is stray light due to the bonding wires  34  prevented, but also, the light-blocking insulators can be prevented from flowing toward the LEDs  28  at the time when the first electrode pads  32  are sealed by the light-blocking insulators.  
      Exemplary embodiments of the present invention are described above, but the present invention is not limited to the embodiment as will be clear to those skilled in the art. Namely, a first aspect of the present invention is an LED array head including: LED arrays at which plural LEDs are positioned; a substrate on which the LED arrays are staggered; first electrode pads provided at end portions of the LED arrays and positioned facing LEDs of adjacent LED arrays; second electrode pads provided on the substrate at a side opposite the adjacent LED arrays and connected to the first electrode pads electrically by wires; and light-blocking elements that block light, which is emitted from the LEDs of the adjacent LED arrays, from reaching the wires.  
      In the first aspect of the present invention, the first electrode pads are disposed at the end portions of the first LED arrays, and are disposed so as to oppose the LEDs disposed at the adjacent LED arrays. Further, the second electrode pads are disposed on the substrate at the side opposite the adjacent LED arrays, and are electrically connected to the first electrode pads by the wires.  
      Here, by providing the light-blocking elements which block the light, which is emitted from the LEDs of the adjacent LED arrays, from reaching the wires, the light from these LEDs is not reflected by the wires, and the occurrence of scattered light and stray light can be prevented.  
      Therefore, it suffices to not carry out stitch bonding at the first electrode pads as a countermeasure to stray light. Thus, the pad strength of the first electrode pads on the LED arrays can be made to be low, and the size of the first electrode pads can be made to be small.  
      Accordingly, because the LED chips are small and the number thereof which can be procured from one wafer is increased, the cost of the LED chip can be decreased. Moreover, because stray light is not generated even though the first electrode pads are small, compact LED arrays can be manufactured, and it is possible to make the image recording device more compact.  
      Further, because it suffices to not carry out stitch bonding at the first electrode pads as a countermeasure to stray light, the first run rate of production is improved. Namely, because the force of bonding to the first electrode pads can be made to be small, there is less damage such as cracking and the like to the LED arrays, and an improvement in the yield of the manufactured product can be anticipated.  
      In the above-described first aspect, the light-blocking elements may include light-blocking insulators covering first electrode pad sides of the wires.  
      In accordance with the above-described structure, the light from the light-emitting points of the LEDs disposed at the adjacent LED arrays is blocked by covering the first electrode pad sides of the wires by the light-blocking insulators. Thus, light is not reflected by the wires within the light-blocking insulators, and the occurrence of scattered light and stray light can be prevented. In this way, substantially the same effects as those of the above-described first aspect can be achieved.  
      In the above-described structure, at least surfaces of the light-blocking insulators may be a blackish color which does not substantially reflect the light from the LEDs.  
      Further, surfaces of the light-blocking insulators may be matte which does not substantially reflect the light from the LEDs.  
      Moreover, in the above-described first aspect, the light-blocking elements may include light-blocking walls provided between the first electrode pads and LEDs which are disposed facing to the first electrode pads.  
      In accordance with the above-described structure, by providing the light-blocking walls between the first electrode pads and the LEDs which are disposed facing to the first electrode pads, the light from the light-emitting points of the LEDs disposed at the adjacent LED arrays is blocked. Therefore, substantially the same effects as those of the above-described first aspect can be achieved.  
      In the above-described structure, the light-blocking walls may be provided in vicinities of the first electrode pads.  
      Further, the light-blocking walls may be disposed between the LED arrays which are adjacent each other.  
      Moreover, the top surfaces of the LEDs of the adjacent LED arrays and top surfaces of the first electrode pads may be different in heights so that light emitted from the LEDs of the adjacent LED arrays does not reach the wires.  
      In the above-described structure, due to the difference in heights between the top surfaces of the first electrode pads and the top surfaces of the LEDs disposed at the adjacent LED arrays, it is possible to make the light emitted from the light-emitting points of the LEDs disposed at the adjacent LED arrays not reach the wires. In this way, substantially the same effects as those of the first aspect of the present invention can be achieved.  
      In the above-described structure, the top surfaces of the LEDs disposed at the adjacent LED arrays may be higher than the top surfaces of the first electrode pads.  
      The top surfaces of the LEDs disposed at the adjacent LED arrays are made to be higher than the top surfaces of the first electrode pads. In this way, in addition to substantially the same effects as the first aspect of the present invention, the light-blocking insulators can be prevented from flowing toward the LEDs at the time when the first electrode pad portions are sealed by the light-blocking insulators.  
      In the above-described structure, the top surfaces of the LEDs disposed at the adjacent LED arrays may be lower than the top surfaces of the first electrode pads.  
      The top surfaces of the LEDs disposed at the adjacent LED arrays are made to be lower than the top surfaces of the first electrode pads. In this way, the light from the light-emitting points of the LEDs disposed at the adjacent LED arrays is blocked by the side wall of the LED array at which the first electrode pads are disposed, and substantially the same effects as the first aspect of the present invention can be achieved.  
      Moreover, the wires may be provided outside of light-emitting regions of the LEDs disposed at the adjacent LED arrays.  
      In accordance with this structure, by providing the wires to be outside of the light-emitting regions of the LEDs disposed at the adjacent LED arrays, the light from the light-emitting points of these LEDs does not reach the wires. In this way, substantially the same effects as those of the first aspect of the present invention can be achieved.  
      In the first aspect of the present invention, the wires may be provided by a low-loop bonding such as Bond Stitch on Ball or the like.  
      In the first aspect of the present invention, a dimension, in a short-side direction, of the LED arrays may be less than or equal to 130 μm. In accordance with this structure, by making the dimension, in the short-side direction, of the LED arrays be less than or equal to 130 μm (it is generally 300 μm), it is possible to make an image recording device more compact.  
      A second aspect of the present invention is an image recording device including an LED array head which includes: LED arrays at which plural LEDs are positioned; a substrate on which the LED arrays are staggered; first electrode pads provided at end portions of the LED arrays and positioned facing LEDs of adjacent LED arrays; second electrode pads provided on the substrate at a side opposite the adjacent LED arrays and connected to the first electrode pads electrically by wires; and light-blocking elements that block light, which is emitted from the LEDs of the adjacent LED arrays, from reaching the wires.  
      Because the present invention is structured as described above, the occurrence of scattered light and stray light can be prevented. Moreover, because it suffices to not carry out stitch bonding at the first electrode pads as a countermeasure to stray light, the pad strength of the first electrode pads on the LED arrays can be made to be low, and the size of the first electrode pads can be made to be small. Therefore, because the LED chips are small and the number thereof which can be procured from one wafer is increased, the cost of the LED chip can be decreased. In addition, because stray light is not generated even though the first electrode pads are small, compact LED arrays can be manufactured, and it is possible to make the image recording device more compact. Still further, because it suffices to not carry out stitch bonding at the first electrode pads as a countermeasure to stray light, the first run rate of production is improved. Namely, because the force of bonding to the first electrode pads can be made to be small, there is less damage such as cracking and the like to the LED arrays, and an improvement in the yield of the manufactured product can be anticipated.  
      The foregoing description of the embodiments of the present invention has been provided for the purpose of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, thereby enabling others skilled in the art to are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents.