Abstract:
An exposure device includes a long board, plural light emitting elements arranged along a longitudinal direction of the board on one face of the board, plural inspection electrodes arranged along the longitudinal direction of the board on the other face of the board, and plural electrical wirings each electrically connects between one of the plural light emitting elements and one of the plural inspection electrodes that is not positioned nearest to the one of the plural light emitting elements.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2011-016560 filed Jan. 28, 2011. 
       BACKGROUND 
     Technical Field 
       [0002]    The present invention relates to an exposure device and an image forming apparatus. 
       SUMMARY 
       [0003]    According to an aspect of the invention, there is provided an exposure device including a long board, plural light emitting elements arranged along a longitudinal direction of the board on one face of the board, plural inspection electrodes arranged along the longitudinal direction of the board on the other face of the board, and plural electrical wirings each electrically connects between one of the plural light emitting elements and one of the plural inspection electrodes that is not positioned nearest to the one of the plural light emitting elements. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0004]    Exemplary embodiments of the present invention will be described in detail based on the following figures, wherein: 
           [0005]      FIG. 1  is an overall configuration view showing the configuration of an image forming apparatus related to an exemplary embodiment of the invention overall; 
           [0006]      FIG. 2  is a perspective view of an exposure device shown in  FIG. 1 ; 
           [0007]      FIG. 3  is a cross-sectional view of the exposure device shown in  FIG. 1 ; 
           [0008]      FIG. 4  is a bottom view of the exposure device shown in  FIG. 1 ; 
           [0009]      FIG. 5  is a side view when a printed wiring board shown in  FIG. 2  is seen from its lateral direction, and is an explanatory view showing an aspect when LED arrays are inspected; 
           [0010]      FIG. 6  is an explanatory view showing an aspect when the LED arrays are inspected, which is shown as a comparative example of  FIG. 5 ; and 
           [0011]      FIG. 7  is an explanatory view similar to  FIG. 5 , showing another aspect of the printed wiring board of  FIG. 5 . 
       
    
    
     DETAILED DESCRIPTION 
       [0012]    An exemplary embodiment of an exposure device and an image forming apparatus related to the invention will be described below with reference to the accompanying drawings. 
         [0013]    (Overall Configuration) 
         [0014]      FIG. 1  shows an example of the configuration of an image forming apparatus that has an exposure device related to the exemplary embodiment of the invention. 
         [0015]    As shown in  FIG. 1 , an apparatus body  10 A of an image forming apparatus  10  is provided with an intermediate transfer body belt  14  serving as an example of an endless belt-shaped body to be transferred, which is stretched over plural rollers  12  and conveyed in the direction of an arrow A by the driving of a motor (not shown). 
         [0016]    The image forming apparatus  10  supports formation of a color image, and has image forming units  28 Y,  28 M,  28 C, and  28 K that form toner images corresponding to four colors of yellow (Y), magenta (M), cyan (C), and black (K). The image forming units  28 Y,  28 M,  28 C, and  28 K are arranged along the longitudinal direction of the intermediate transfer body belt  14 , and are detachably supported by the apparatus body  10 A. 
         [0017]    In addition, members provided for the respective colors are designated by adding letters (Y/M/C/K) indicating the colors to the ends of reference numerals, respectively. Particularly when description is made without distinguishing the colors, the letters at the ends of the reference numerals are omitted. 
         [0018]    The image forming units  28 Y,  28 M,  28 C, and  28 K respectively include photoreceptor drums  16 Y,  16 M,  16 C, and  16 K serving as examples of image carriers that are rotated in the clockwise direction by a driving unit composed of a motor and gears that are not shown. 
         [0019]    A charging roller  18  for uniformly charging a surface of the photoreceptor drum  16  with given potential is arranged at a peripheral surface of each photoreceptor drum  16 . The charging roller  18  is a conductive roller, and a peripheral surface thereof comes into contact with the peripheral surface of the photoreceptor drum  16 . The charging roller  18  is arranged such that the axis direction of the charging roller  18  and the axis direction of the photoreceptor drum  16  become parallel to each other. 
         [0020]    An LED print head (hereinafter referred to as “LPH”)  20  serving as an example of an exposure device is arranged at the peripheral surface of each photoreceptor drum  16  on the downstream side of the charging roller  18  in the rotational direction of the photoreceptor drum. The LPH  20  is long, and is arranged along the axial direction of the photoreceptor drum  16 . The LPH  20  has an LED (light-emitting diode) array serving as an example of a light emitting element, as a light source. The LPH  20  irradiates the photoreceptor drum  16  with light beams according to image data, thereby forming an electrostatic latent image on the surface of the photoreceptor drum  16 . The LPH  20  will be described below in detail. 
         [0021]    A developing device  22  is arranged at the peripheral surface of each photoreceptor drum  16  on the downstream side of the LPH  20  in the rotational direction of the photoreceptor drum. The developing device  22  is provided to develop the electrostatic latent image formed on the surface of the photoreceptor drum  16  with a toner for each color (yellow/magenta/cyan/black) so as to form a toner image. 
         [0022]    Specifically, the developing device  22  has a cylindrical developing roller  24  that is arranged in close proximity to the photoreceptor drum  16 , and is rotatably provided. A development bias is applied to the developing roller  24 , and a toner loaded into the developing device  22  is adhered to a peripheral surface of the developing roller. By the rotation of the developing roller  24 , the toner adhered to the developing roller  24  is conveyed to the surface of the photoreceptor drum  16 , the toner is rubbed against the photoreceptor drum  16 , and the electrostatic latent image formed on the surface of the photoreceptor drum  16  is developed as a toner image. 
         [0023]    A transfer roller  30  serving as an example of a transfer device that transfers the toner image on each photoreceptor drum  16  to the intermediate transfer body belt  14  is provided at the peripheral surface of each photoreceptor drum  16  on the downstream side of the developing device  22  in the rotational direction of the photoreceptor drum. The transfer roller  30  is charged with a given potential and rotated counterclockwise to convey the intermediate transfer body belt  14  at a given speed and presses the intermediate transfer body belt  14  against the photoreceptor drum  16 . Thereby, the toner image on the surface of the photoreceptor drum  16  is transferred onto the intermediate transfer body belt  14 . 
         [0024]    A cleaning blade  26  is arranged on the peripheral surface of each photoreceptor drum  16  on the downstream side of the transfer roller  30 . The cleaning blade  26  is disposed such that one end thereof comes into contact with the surface of the photoreceptor drum  16 , and recovers the toner remaining on the photoreceptor drum  16  without being transferred to the intermediate transfer body belt  14 , and scrapes off and recovers other color toners that have adhered onto the photoreceptor drum  16  at the time of transfer. 
         [0025]    The respective toner images formed by the respective image forming units  28  are transferred so as to overlap each other on a belt surface of the intermediate transfer body belt  14 . Thereby, a color toner image is formed on the intermediate transfer body belt  14 . Hereinafter, a toner image to which four color toner images are transferred in an overlapping manner is referred to as a “final toner image”. 
         [0026]    A secondary transfer device  34  configured to include two facing rollers  34 A and  343  is disposed on the downstream side of the four photoreceptor drums  16  in the conveying direction of the intermediate transfer body belt  14 . In the secondary transfer device  34 , the final toner image formed on the intermediate transfer body belt  14  is transferred to a recording paper P that has been taken out from a paper tray  36  provided at the bottom of the image forming apparatus  10  and has been conveyed to between the rollers  34 A and  34 B. 
         [0027]    A fixing device  40  configured to include a heating roller  40 A and a pressurizing roller  40 B is disposed at a conveying path for the recording paper P to which the final toner image has been transferred. The recording paper P conveyed to the fixing device  40  is conveyed while pinched between the heating roller  40 A and the pressurizing roller  40 B. Thereby, the toner on the recording paper P is melted, is brought into pressure contact with the recording paper  2 , and is fixed on the recording paper P. 
         [0028]    On the other hand, in an outer peripheral surface of the intermediate transfer body belt  14 , a cleaning device  42  that recovers the toner remaining on the intermediate transfer body belt  14  without being transferred to the recording paper P by the secondary transfer device  34  is disposed on the downstream side of the secondary transfer device  34  in the conveying direction of the intermediate transfer body belt  14 . The cleaning device  42  has a blade  44  that comes into contact with the intermediate transfer body belt  14 , and rubs off the toner remaining on the intermediate transfer body belt  14  to recover the toner. 
         [0029]    In the image forming apparatus  10  configured as above, an image is formed as follows. 
         [0030]    First, the surface of the photoreceptor drum  16  is uniformly negatively-charged by the charging roller  18 . Next, exposure is performed on the surface of the charged photoreceptor drum  16 , on the basis of image data to be printed by the LHP  20 , and an electrostatic latent image is formed on the surface of the photoreceptor drum  16 . 
         [0031]    Next, when the electrostatic latent image of the photoreceptor drum  16  surface passes by the developing roller of the developing device  22 , a toner adheres to the electrostatic latent image due to an electrostatic force, whereby the electrostatic latent image is visualized as a toner image. 
         [0032]    Next, respective visualized color toner images are sequentially transferred to the intermediate transfer body belt  14  by the transfer rollers  30 , and a final toner image is formed in color on the intermediate transfer body belt  14 . 
         [0033]    Next, the final toner image on the intermediate transfer body belt  14  is sent to between the rollers  34 A and  34 B of the secondary transfer device  34 , and the final toner image is transferred to the recording paper P that is taken out from the paper tray  36 , and similarly conveyed to between the rollers  34 A and  34 B. 
         [0034]    Next, the toner image transferred to the recording paper P is fixed as a permanent image by the fixing device  40 . The recording paper P that has passed through the fixing device  40  is ejected to the outside of the apparatus. 
         [0035]    (Configuration of LPH  20 ) 
         [0036]    Next, the LPH  20  will be described in detail. 
         [0037]    As shown in  FIGS. 2 ,  3 , and  4 , the LPH  20  includes a printed wiring board  52  as an example of a board, a lens array  54  arranged so as to face the printed wiring board  52 , and a housing  58  that houses the printed wiring board  52  and the lens array  54 . 
         [0038]    The printed wiring board  52  has a long plate shape, and plural (specifically, twenty) LED arrays  62  are alternately arranged along the longitudinal direction of the printed wiring board  52  on a top face of the printed wiring board  52 . Although not shown, plural (specifically, 256) light emitting points composed of LEDs are arranged in one row along the longitudinal direction at each LED array  62 . Each LED array  62  radiates a light beam toward the lens array  54 . 
         [0039]    The lens array  54  is pinched and fixed to the housing  58  above the printed wiring board  52 , and the light beam radiated from each LED array  62  is focused on the surface of the photoreceptor drum  16 . 
         [0040]    The printed wiring board  52  is attached to the housing  58  by adhesive members (adhesive)  60  (schematically shown in a triangular shape in the drawing) serving as an example of a fixing section. The adhesive members  60  are arranged in pairs with the LED arrays  62  therebetween on the top face of the printed wiring board  52 , and are provided in plural places so as to be dotted along the longitudinal direction of the printed wiring board  52 . In addition, the fixing section is not limited to the adhesive members  60 , and may be configured, for example, by an engaging claw provided on the housing  58 , and an engaging hole having the engaging claw inserted thereinto and engaged therewith, and provided in the printed wiring board  52 . 
         [0041]    As shown in  FIGS. 3 and 4 , plural inspection electrodes  64  are arranged along the longitudinal direction of the printed wiring board  52  on a bottom face of the printed wiring board  52 . The same number of (twenty) inspection electrodes  64  as the LED arrays  62  are provided, and each inspection electrode  64  is arranged so as to correspond to a central portion of each LED array  62  in the longitudinal direction thereof. That is, each inspection electrode  64  is arranged at a position that faces each LED array  62  with the printed wiring board  52  therebetween. The inspection electrodes  64  are electrodes (test pads) used in light emission inspection of the LED arrays  62 . In addition, the inspection electrodes  64  are very thin because the inspection electrodes are formed using metallic foils, such as the same copper foil as a circuit pattern (not shown) of the printed wiring board  52 . However, the inspection electrodes are shown thickly in  FIGS. 3 , and  5  to  7  in order to make description easily understood. 
         [0042]    (Light Emission Inspection) 
         [0043]    Light emission inspection will be described below.  FIG. 5  is a side view when the printed wiring board  52  is seen from its lateral direction, showing an aspect in regard to light emission inspection of the LED arrays  62 . In the light emission inspection, inspection probes  66  are sequentially pressed against the inspection electrodes  64 , the electric power for making the LED arrays  62  emit light is supplied to the electrodes, and a control signal for making each LED array  62  actually emit light is transmitted. Then, a CCD camera  68  is arranged above the LED arrays  62  to perform scanning (movement) in the longitudinal direction, and sequentially performs the light emission inspection of the LED arrays  62  one by one from one end side (the left side in  FIG. 5 ). The light emission inspection is to confirm the presence of light emission of 256 light emitting points of each LED array, the light emission intensity when a given current is made to flow, the light emission positions of the respective light emitting points, and the like. In addition, the plural inspection probes  66  are provided so as to correspond to the inspection electrodes  64 , respectively. Additionally, illustration of the lens array  54  and the housing  58  is omitted in  FIG. 5 , and actual light emission inspection is performed on a finished product of the LPH  20  that is assembled and finished. 
         [0044]    Here, in the printed wiring board  52 , a first LED array  62  (shown as “SLED 1 ” in the drawing) from the left in the drawing is connected to the inspection electrode  64  (shown as “PAD 1 ” in the drawing) arranged directly below a third LED array  62  (shown as “SLED 3 ” in the drawing). Additionally, a second LED array  62  (shown as “SLED 2 ” in the drawing) is connected to the inspection electrode  64  (shown as “PGD 2 ” in the drawing) arranged directly below a fourth LED array  62  (shown as “SLED 4 ” in the drawing). Additionally, the third LED array  62  (shown as “SLED 3 ” in the drawing) is connected to the inspection electrode  64  (shown as “PAD 3 ” in the drawing) arranged directly below the first LED array  62  (shown as “SLED 1 ” in the drawing). Additionally, the fourth LED array  62  (shown as “SLED 4 ” in the drawing) is connected to the inspection electrode  64  (shown as “PAD 4 ” in the drawing) arranged directly below the second LED array  62  (shown as “SLED 2 ” in the drawing). After that, the same is true on fifth to eighth LED arrays  62  and the inspection electrodes  64 , ninth to twelfth LED arrays  62  and the inspection electrodes  64 , thirteenth to sixteenth LED arrays  62  and the inspection electrodes  64 , and seventeenth to twentieth LED arrays  62  and the inspection electrodes  64 . In addition, SLED is short for Self Scanning Light Emitting Diode. 
         [0045]    In this way, in the printed wiring board  52 , each LED array  62  is connected to the inspection electrode  64  that is not arranged directly therebelow. Only the inspection probe corresponding to the inspection electrode  64  (PAD 1 ) connected to the first LED array  62  among the plural inspection probes  66  is pressed against the inspection electrode  64  (PAD 1 ). Next, only the inspection probe  66  corresponding to the inspection electrode  64  (PAD 2 ) connected to the second LED array  62  among the plural inspection probes  66  is pressed against the inspection electrode  64  (PAD 2 ). Thereafter, similarly, the inspection probes  66  to be pressed are sequentially switched up to the inspection probe  66  corresponding to the twentieth LED array  62 . Thereby, the first LED array  62  to the twentieth LED array  62  emit light sequentially. Scanning of the CCD camera  68  is performed from the first LED array  62  toward the twentieth LED array  62  and light emission inspection of all the LED arrays  62  is performed, so as to interlock with this sequential light emission. 
         [0046]      FIG. 6  shows an aspect of light emission inspection shown as a comparative example in respect to  FIG. 5 . In a printed wiring board  100  shown in  FIG. 6 , each LED array  62  is connected to the inspection electrode  64  arranged directly therebelow as shown. Additionally, at the time of light emission inspection, the plural inspection probes  66  are all pressed against the inspection electrodes  64  simultaneously. On the basis of such a configuration, control signals for making the first to twentieth LED arrays  62  emit light sequentially are transmitted to the respective LED arrays  62  through the respective inspection probes  66 , and the first to twentieth LED arrays  62  are made to emit light sequentially. Then, scanning of the CCD camera  68  is performed from the first LED array  62  toward the twentieth LED array  62 , thereby performing the light emission inspection of all the LED arrays  62 . 
         [0047]    In the printed wiring board  100  of the comparative example shown in  FIG. 6 , each LED array  62  is connected to the inspection electrode  64  arranged directly therebelow. Thus, strain  70  of the printed wiring board  100  originating from a pressing force pressed by the inspection probe  66  will exert an influence on each LED array  62  to be subjected to the light emission inspection. That is, the light emission inspection is performed in the state where the strain  70  exerts an influence on the LED array  62  to be subjected to the light emission inspection, and an optical axis of the light emitting points of the LED array  62  deviates, so that the light emission inspection may not be performed with high precision. In addition, if the pressure that the inspection probe  66  applies is made small, poor contact occurs between the inspection probe and the inspection electrodes  64 , which causes poor inspection. Additionally, in the comparative example shown in  FIG. 6 , even if the plural inspection probes  66  are pushed against the inspection electrodes  64  sequentially at the time of light emission inspection, the strain  70  of the printed wiring board  100  originating from the pressing force pressed by the inspection probe  66  exerts an influence on the LED array  62  to be subjected to the light emission inspection. This is because each LED array  62  is connected to the inspection electrode  64  arranged directly therebelow. 
         [0048]    In contrast, in the light emission inspection in the present exemplary embodiment shown in  FIG. 5 , each LED array  62  is connected to the inspection electrode  64  that is not arranged directly therebelow, and the inspection probes  66  are pressed against the inspection electrodes  64  sequentially. Thus, the strain  70  of the printed wiring board  52  resulting from the pressing force of the inspection probe  66  does not easily exert an influence on the LED array  62  to be subjected to the light emission inspection. Accordingly, deviation of the optical axis of the light emitting points of the LED array  62  to be subjected to the light emission inspection may be suppressed, and the light emission inspection may be performed with high precision. 
         [0049]      FIG. 7  shows a modification aspect of the printed wiring board  52  in the present exemplary embodiment shown in  FIG. 5 . Here, in a printed wiring board  52   a  shown in  FIG. 7 , a first LED array  62  (SLED 1 ) from the left in the drawing is connected to the inspection electrode  64  (PAD 1 ) arranged directly below a second LED array  62  (SLED 2 ). Additionally, the second LED array  62  (SLED 2 ) is connected to the inspection electrode  64  (PAD 2 ) arranged directly below the first LED array  62  (SLED 1 ). The same is true of the third to fourth LED arrays  62  and the inspection electrodes  64 , fifth to sixth LED arrays  62  and the inspection electrodes  64 , . . . , and nineteenth to twentieth LED arrays  62  and the inspection electrodes  64 . That is, each LED array  62  is connected to the inspection electrode  64  arranged directly below its adjacent LED array  62 . 
         [0050]    Additionally, in  FIG. 7 , when description is made including the arrangement relationship of the plural dotted adhesive members  60  mentioned above, the adhesive members  60  are respectively arranged so as to be interposed between the first LED array  62  (SLED 1 ) and the second LED array  62  (SLED 2 ), between the third LED array  62  (SLEDS) and the fourth LED array  62  (SLED 4 ), . . . , and between the nineteenth LED array  62  and the twentieth LED array  62 , in side view shown in  FIG. 7 . 
         [0051]    Here, for example, in a case where each LED array  62  is connected to the inspection electrode  64  arranged directly below its adjacent LED array  62 , and the adhesive member  60  is not interposed between its adjacent LED array  62 , the same effects as the exemplary embodiment described with reference to  FIG. 5  may be obtained. However, there is a case in which a higher-precision light emission inspection may be required, such as a case where a high-precision image is formed. 
         [0052]    Thus, in the printed wiring board  52   a , although each LED array  62  is connected to the inspection electrode  64  arranged directly below its adjacent LED array  62 , the LED array is connected to the inspection electrode  64  at a position over the adhesive member  60 . Since the arrangement point of the adhesive member  60  is considered as a fixed end, the strain  70  does not easily exert an influence on the LED array  62  to be subjected to the light emission inspection. Accordingly, even if each LED array  62  is connected to the inspection electrode  64  arranged directly below its adjacent LED array  62 , the light emission inspection may be performed with high precision. Additionally, in the printed wiring board  52   a , each LED array  62  is connected to the inspection electrode  64  arranged directly below its adjacent LED array  62 . Thus, a wiring path that connects the LED array  62  and the inspection electrode  64  is shortened compared to the printed wiring board  52  shown in  FIG. 5 . 
         [0053]    In addition, although the plural LED arrays  62  have been alternately arranged in the LPH  20  related to the present exemplary embodiment, the LED arrays may simply be arranged linearly in one row. Additionally, although the above-described exemplary embodiment shows that there are 20 LED arrays  62  and there are 256 light emitting points of each LED array  62 , the invention is not meant to be limited to these numbers. 
         [0054]    The foregoing description of the exemplary embodiments of the present invention has been provided for the purposes 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 understand the invention for various embodiments and with the various modifications as 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.