Patent Publication Number: US-9417550-B2

Title: Image forming apparatus that indicates operating status using luminous body

Description:
INCORPORATION BY REFERENCE 
     This application is a continuation of U.S. application Ser. No. 14/635,016, filed on Mar. 2, 2015, which is a continuation of U.S. application Ser. No. 13/854,359, filed on Apr. 1, 2013, now U.S. Pat. No. 8,989,612, which is based upon and claims the benefit of priority from Japanese Patent Application No. 2012-085335, filed on Apr. 4, 2012, the entire contents of each of which are incorporated herein by reference. 
    
    
     BACKGROUND 
     Unless otherwise indicated herein, the description in this section is not prior art to the claims in this application and is not admitted to be prior art by inclusion in this section. 
     The present disclosure relates to an image forming apparatus that indicates operating status using a luminous body. 
     In image forming apparatuses, such as printers, copiers, facsimiles, and multifunction peripherals that combine these capabilities, an apparatus is known which has an indicator for indicating status information of the apparatus to the user. The status information is, for example, information about the status of a connection with a local area network, the status of reception of image data from an external device, or occurrence of trouble in the apparatus, such as a sheet jam or running out of toner. The indicator is typically formed by a luminous body, such as a light emitting diode (LED). In accordance with the status information, the luminous body illuminates in a predetermined pattern. Viewing the illumination of the luminous body allows the user to recognize the status information of the image forming apparatus. 
     In such an image forming apparatus of the related art, an indicator indicating status information is positioned based on the assumption that it will be viewed from a specific direction relative to a main body of the apparatus. Since such an indicator has a low level of visibility from directions other than the specific direction, the user may not be able to recognize the status information. For example, if the luminous portion of the indicator is located at the front of the apparatus, the luminous portion cannot be clearly viewed from the side or back of the apparatus. 
     SUMMARY 
     An image forming apparatus according to an embodiment of the present disclosure includes an image forming section, a body housing, a protruding housing, a light diffusing portion, a light source, a light guide path, and a control unit. The image forming section is configured to perform image formation on a sheet. The body housing is formed by a box body with a top surface, and configured to contain the image forming section. The protruding housing is located on the top surface, and has a top portion protruding upwardly above the top surface. The light diffusing portion is located in or near the top portion of the protruding housing. The light source is located inside the body housing or the protruding housing, and configured to emit light. The light guide path is configured to guide light emitted by the light source to the light diffusing portion. The control unit is configured to control illumination of the light source based on the information related to the image formation. 
     Additional features and advantages are described herein, and will be apparent from the following Detailed Description and the figures. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  is an external perspective view of an image forming apparatus according to an embodiment of the present disclosure; 
         FIG. 2  is a cross-sectional view illustrating an internal structure of the image forming apparatus; 
         FIG. 3  is a perspective view of an operation section cover; 
         FIG. 4  is a top view of an operation section unit; 
         FIG. 5  is a cross-sectional view taken along line V-V of  FIG. 4 ; 
         FIG. 6  is a top view of an operation-section substrate unit; 
         FIG. 7A  and  FIG. 7B  are perspective views of the operation-section substrate unit; 
         FIG. 8  is an enlarged perspective view of a major part of the operation-section substrate unit; 
         FIG. 9  is a perspective view of the operation-section substrate unit illustrated in  FIG. 8  and a light guide unit attached thereto; 
         FIG. 10A  to  FIG. 10D  are perspective views of the light guide unit; 
         FIG. 11  is an enlarged perspective view of an operation section; 
         FIG. 12  is an enlarged perspective view of a status indicator; 
         FIG. 13  is a cross-sectional view of the operation section; 
         FIG. 14  is an enlarged cross-sectional view of the status indicator, and provides a further enlarged cross-sectional view of an end portion of a light guide in a dotted circle; and 
         FIG. 15  is a block diagram illustrating an electrical configuration of the image forming apparatus. 
     
    
    
     DETAILED DESCRIPTION 
     An example of the apparatus is described herein. Other example embodiments or features may further be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented herein. In the following detailed description, reference is made to the accompanying drawings, which form a part thereof. 
     The example embodiments described herein are not meant to be limiting. It will be readily understood that the aspects of the present disclosure, as generally described herein, and illustrated in the drawings, can be arranged, substituted, combined, separated, and designed in a wide variety of different configurations, all of which are explicitly contemplated herein. 
     An image forming apparatus  10  according to an embodiment of the present disclosure will now be described with reference to the drawings. In this embodiment, a tandem color printer will be described as an example of the image forming apparatus. The image forming apparatus may be, for example, a monochrome printer, a copier, a facsimile, or a multifunction peripheral that combines their capabilities. 
       FIG. 1  is an external perspective view of the image forming apparatus  10 . The image forming apparatus  10  includes a body housing  11  that contains devices, such as an image forming section  13  and other components described below. The body housing  11  is in the shape of a substantially cubic box. The body housing  11  has a bottom surface  11 B, four side surfaces  11 S that extend vertically from the respective four sides of the bottom surface  11 B, and a top surface  11 T that covers the top of the space defined by the side surfaces  11 S. 
     The top surface  11 T includes a paper ejection unit  17  to which a sheet on which an image has been formed is ejected, an ejection portion  111 E from which the sheet is ejected to the paper ejection unit  17 , and an operation section OP. The paper ejection unit  17  includes a paper output tray  171  that receives the sheet ejected from the ejection portion  111 E. The operation section OP is located at the upper right front of the body housing  11 . The operation section OP includes an operation key portion  31 , a display panel portion  32 , and a state indicator  33 . 
     The operation key portion  31  includes a numeric keypad, a start key, and various operation buttons. The operation key portion  31  accepts an operation instruction for the image forming apparatus  10  from the user. The display panel portion  32  includes a liquid-crystal display panel  42  (see  FIG. 5 ) and displays, for example, printing-related information, operation guidance, and error information. 
     The status indicator  33  uses an LED lamp unit  43  (see  FIG. 6 ) as a light source. The status indicator  33  lights the LED lamp unit  43  in accordance with predetermined patterns to present various types of state information indicating the status of the image forming apparatus  10 . In an embodiment, the status indicator  33  includes three luminous portions (light diffusing portions or end portions  53  illustrated in  FIG. 9  etc.). The status indicator  33  turns on, turns off, or intermittently turns on the luminous portions to generate status information. The status information is, for example, information about status of the connection of the image forming apparatus  10  with a local area network, status of the reception of image data from an external device, or the occurrence of trouble in the image forming apparatus  10 , such as a sheet jam or running out of toner. 
     Although the top surface  11 T is a flat surface, the paper output tray  171  slopes downwardly toward the ejection portion  111 E. The operation section OP partially protrudes upwardly from the top surface  11 T. Specifically, a convex portion (protruding housing) having a cross-sectional mountain-like shape in the front-back direction is located at the upper right front of the top surface  11 T. The liquid-crystal display panel  42  is located along a forward inclined surface of the convex portion, and the status indicator  33  is located at the top of the convex portion. The front part of the top surface  11 T is formed by an operation section unit  30  (operation section cover  300 ). The operation section unit  30  will be described in detail below. 
       FIG. 2  is a cross-sectional view illustrating an internal structure of the image forming apparatus  10 . The body housing  11  includes a paper feed section  12  that feeds a sheet P, the image forming section  13  that forms a toner image to be transferred onto the sheet P fed from the paper feed section  12 , an intermediate transfer unit  14  where the toner image is primary-transferred, a toner supply unit  15  that supplies toner to the image forming section  13 , and a fixing unit  16  that fixes an unfixed toner image on the sheet P. After being subjected to the fixing operation by the fixing unit  16 , the sheet P is ejected to the paper ejection unit  17 . 
     The body housing  11  further includes a sheet conveying path  111  to the right of the image forming section  13 . The sheet conveying path  111  extends in the up-down direction. The sheet conveying path  111  is provided with a conveying roller pair  112  that feed a sheet to an appropriate place. The sheet conveying path  111  is also provided with a registration roller pair  113  that not only performs skew correction of the sheet, but also feeds the sheet into a nip portion for secondary transfer (described below) at predetermined timing. The registration roller pair  113  is located upstream of the nip portion in the sheet conveying path  111 . The sheet conveying path  111  is a feeding path for feeding the sheet P from the paper feed section  12 , through the image forming section  13  and the fixing unit  16 , to the paper ejection unit  17  (ejection portion  111 E). 
     The paper feed section  12  includes a paper feed tray  121 , a pickup roller  122 , and a paper-feed roller pair  123 . The paper feed tray  121  is removably mounted in the lower part of the body housing  11 . The paper feed tray  121  holds a sheet stack P 1  formed by stacking a plurality of sheets P. The pickup roller  122  picks up each sheet P at the top of the sheet stack P 1  held in the paper feed tray  121 . The paper-feed roller pair  123  feeds the sheet P picked up by the pickup roller  122  to the sheet conveying path  111 . 
     The paper feed section  12  includes a manual paper-feed unit on the front side of the body housing  11 . The manual paper-feed unit includes a manual feed tray  124 , a pickup roller  125 , and a paper-feed roller pair  126 . The manual feed tray  124  is a tray on which a sheet P to be manually fed is placed. For manually feeding of the sheet P, the manual feed tray  124  opens from one side of the body housing  11  as illustrated in  FIG. 2 . The pickup roller  125  picks up the sheet P placed on the manual feed tray  124 . The paper-feed roller pair  126  feeds the sheet P picked up by the pickup roller  125  to the sheet conveying path  111 . 
     The image forming section  13  forms a toner image to be transferred to the sheet P. The image forming section  13  includes a plurality of image forming units that form toner images of different colors. In an embodiment, the image forming units are a magenta unit  13 M using a magenta (M) developer, a cyan unit  13 C using a cyan (C) developer, a yellow unit  13 Y using a yellow (Y) developer, and a black unit  13 Bk using a black (Bk) developer, which are sequentially arranged from the upstream side to the downstream side (i.e., from the front side to the back side shown in  FIG. 2 ) in the running direction of an intermediate transfer belt  141  (described below). Each of the units  13 M,  13 C,  13 Y, and  13 Bk includes a photosensitive drum  20  and a charging device  21 , a developing device  23 , a primary transfer roller  24 , and a cleaning device  25  disposed around the photosensitive drum  20 . An exposure device  22  common to the image forming units  13 M,  13 C,  13 Y, and  13 Bk is located below the units. 
     The photosensitive drum  20  rotates about its axis, so that an electrostatic latent image and a toner image are formed on the periphery of the photosensitive drum  20 . A photosensitive drum made of amorphous silicon (a-Si)-based material may be used as the photosensitive drum  20 . The charging device  21  uniformly charges the surface of the photosensitive drum  20 . A contact charging device including a charging roller and a charge cleaning brush for removing toner adhering to the charging roller may be used as the charging device  21 . The exposure device  22  includes a light source and various optical units, such as a polygonal mirror, a reflecting mirror, and a deflecting mirror. The exposure device  22  forms an electrostatic latent image by irradiating the uniformly charged periphery of the photosensitive drum  20  with light outputted based on the image data. 
     The developing device  23  supplies toner to the periphery of the photosensitive drum  20  to develop the electrostatic latent image formed on the photosensitive drum  20 . The primary transfer roller  24  and the photosensitive drum  20  form a nip portion, with the intermediate transfer belt  141  of the intermediate transfer unit  14  interposed therebetween. The primary transfer roller  24  primary-transfers the toner image from the photosensitive drum  20  onto the intermediate transfer belt  141 . The cleaning device  25  cleans the periphery of the photosensitive drum  20  after the transfer of the toner image. 
     The intermediate transfer unit  14  is located in a space between the image forming section  13  and the toner supply unit  15 . The intermediate transfer unit  14  includes the intermediate transfer belt  141 , and a driving roller  142  and a driven roller  143  rotatably supported by a unit frame (not shown). The intermediate transfer belt  141  is an endless belt that runs between the driving roller  142  and the driven roller  143  such that the periphery of the intermediate transfer belt  141  is in contact with the periphery of each of the photosensitive drums  20 . The driving roller  142  is given a rotary driving force, and the intermediate transfer belt  141  is driven to run by rotation of the driving roller  142 . A belt cleaning device  144 , that removes toner remaining on the periphery of the intermediate transfer belt  141 , is positioned near the driven roller  143 . 
     A secondary transfer roller  145  is positioned to face the driving roller  142 . The secondary transfer roller  145  is pressed against the periphery of the intermediate transfer belt  141  to form a secondary-transfer nip portion. A toner image primary-transferred onto the intermediate transfer belt  141  is secondary-transferred, at the secondary-transfer nip portion, onto a sheet P fed from the paper feed section  12 . 
     The toner supply unit  15  stores toners for use in image formation. In an embodiment, the toner supply unit  15  includes a magenta toner container  15 M, a cyan toner container  15 C, a yellow toner container  15 Y, and a black toner container  15 Bk. The toner containers  15 M,  15 C,  15 Y, and  15 Bk store toners of MCYBk colors to be supplied. The toner containers  15 M,  15 C,  15 Y, and  15 Bk supply the toners of the respective MCYBk colors, through a toner conveying unit (not shown), to the corresponding developing devices  23  of the image forming units  13 M,  13 C,  13 Y, and  13 Bk. 
     The fixing unit  16  includes a heating roller  161  having an internal heat source, a fixing roller  162  positioned to face the heating roller  161 , a fixing belt  163  extending between the fixing roller  162  and the heating roller  161 , and a pressure roller  164  positioned to face the fixing roller  162  with the fixing belt  163  interposed therebetween. The fixing roller  162  and the pressure roller  164  form a fixing nip portion therebetween. The sheet P fed to the fixing unit  16  is subjected to heat and pressure by passing through the fixing nip portion. Thus, the toner image transferred onto the sheet P at the secondary-transfer nip portion is fixed to the sheet P. After being subjected to the fixing operation, the sheet P is fed through the sheet conveying path  111  running from the upper part of the fixing unit  16 , and ejected through the ejection portion  111 E toward the paper output tray  171 . 
     The operation section unit  30  located in the front part of the top surface  11 T of the body housing  11  will now be described. The operation section unit  30  includes the operation section cover  300  that forms part of the top surface  11 T.  FIG. 3  is a perspective view of the operation section cover  300 . The operation section cover  300  is located on the front side of the top surface  11 T. The outer surface of the operation section cover  300  forms part of the outer body of the image forming apparatus  10 . 
     The operation section cover  300  includes a top plate  301 T, a side plate  301 S extended from the front, right, and left edges of the top plate  301 T downward, and a rectangular cover body  301  longer in the right-left direction. The cover body  301  includes a paper output recess  302  formed in the central region, an arm  303  jutting out of a left part of the back edge, an operation key housing  304  at the right front, and a protruding housing  305  at the right back. 
     The paper output recess  302  is a shallow recess that forms a front end portion of the paper ejection unit  17  (paper output tray  171 ). The paper output recess  302  has a recessed portion  302 R in the center in the right-left direction. The user can insert fingers into the recessed portion  302 R to remove a sheet. The arm  303  pivotably connects the operation section cover  300  to the body housing  11  (see  FIG. 4  and  FIG. 5 ). The arm  303  is provided with a pivot supporting point  303 S jutting to the right. The operation section cover  300  pivots, about the pivot supporting point  303 S, between open and closed positions relative to the body housing  11 . The operation key housing  304  covers the operation key portion  31 . The operation key housing  304  includes a plurality of windows  304 W that allow various keys to be exposed. 
     The protruding housing  305  contains the display panel portion  32  and the state indicator  33 . The protruding housing  305  is located on the top plate  301 T (top surface  11 T) and has a top portion  305 T protruding upwardly above the top plate  301 T. In side view in the right-left direction, the protruding housing  305  has an upward slope  305 U rising from the front to the back, the top portion  305 T formed by a convex curved surface, and a downward slope  305 D falling from the front to the back. The upward slope  305 U is provided with a rectangular opening  306  that allows the liquid-crystal display panel  42  (see  FIG. 5 ) to be exposed. The top portion  305 T is provided with three grooves (notches)  307  extending in the front-back direction. To circumferentially diffuse light emitted from the end portions  53  of a light guide unit  50  (described below), the grooves  307  are formed by notching parts of the top portion  305 T, which is formed by a convex curved surface, to be recessed downwardly (see  FIG. 12 ). 
       FIG. 4  is a top view of the operation section unit  30 , and  FIG. 5  is a cross-sectional view taken along line V-V of  FIG. 4 . The operation section unit  30  includes the operation section cover  300  and an operation-section substrate unit  40  assembled to the operation section cover  300 . The operation-section substrate unit  40  includes a printed circuit board  40 P, key switches  41  mounted on the printed circuit board  40 P, the liquid-crystal display panel  42 , and the LED lamp unit  43  (light source). 
       FIG. 6  is a top view of the operation-section substrate unit  40 , and  FIG. 7A  and  FIG. 7B  are perspective views of the operation-section substrate unit  40 .  FIG. 7B  is an inverted perspective view of  FIG. 7A . 
     The printed circuit board  40 P has a switch pattern portion  401  having a predetermined circuit pattern and extending from the front to the center thereof, a panel supporting portion  402  adjacent to the switch pattern portion  401 , and a back portion  403  having the LED lamp unit  43  mounted thereon. 
     The key switches  41  correspond to respective key buttons  311  (see  FIG. 4  and  FIG. 5 ) actually touched by the user. The key switches  41  are mounted on the switch pattern portion  401  of the printed circuit board  40 P. When one of the key buttons  311  is pressed down, the corresponding key switch  41  is activated and a switch pattern immediately below the key switch  41  conducts, so that a key controller (not shown) acquires a press-down signal. The key buttons  311  serve as keys of the numeric keypad and the start key described above. 
     The liquid-crystal display panel  42  is rectangular in shape and is assembled to a frame  421  having an opening that allows the display panel portion  32  to be exposed. The frame  421  is supported by supporting plates  422  and  423  vertically extending at both ends of the panel supporting portion  402  of the printed circuit board  40 P. The frame  421  is supported at an angle of inclination of the upward slope  305 U of the protruding housing  305 . 
     The LED lamp unit  43  is a luminous member formed by molding a LED chip with transparent resin. The LED lamp unit  43  is mounted on the back portion  403  of the printed circuit board  40 P. In an embodiment, first, second, and third LED lamps  43 A,  43 B, and  43 C are provided as light sources. However, it is only necessary that at least one LED lamp be provided. For providing more information based on the illumination state of the lamp, it is preferable to provide more than one LED lamp. 
     The first and second LED lamps  43 A and  43 B each contain a green LED chip, whereas the third LED lamp  43 C contains a yellow LED chip. Partition plates  404  are provided between the first and second LED lamps  43 A and  43 B and between the second and third LED lamps  43 B and  43 C to prevent leakage of light. The partition plates  404  also serve to support the back surface of the center portion of the frame  421  that holds the liquid-crystal display panel  42 . 
     In an embodiment, light emitted from the LED lamp unit  43  is diffused outward from the top portion  305 T of the protruding housing  305 , which is at the highest position in the image forming apparatus  10 . A light guide path (light guide unit  50 ) is used to guide the light from the top surface (light emitting portion) of the LED lamp unit  43  to the top portion  305 T (see  FIG. 9 ). A configuration related to the light guide unit  50  will now be described in detail. 
       FIG. 8  is an enlarged perspective view of a major part of the operation-section substrate unit  40 ,  FIG. 9  is a perspective view of the operation-section substrate unit  40  illustrated in  FIG. 8  and the light guide unit  50  attached thereto, and  FIG. 10A  to  FIG. 10D  are perspective views of the light guide unit  50 .  FIG. 10A  to  FIG. 10D  illustrate the light guide unit  50  as viewed from different directions. The light guide unit  50  includes first, second, and third unit light guides  51 A,  51 B, and  51 C arranged side by side, and connecting ribs  50 L (joint members) that connect them to form a single unit. The first, second, and third unit light guides  51 A,  51 B, and  51 C correspond to the first, second, and third LED lamps  43 A,  43 B, and  43 C, respectively. The unit light guides  51 A,  51 B, and  51 C serve as light guide paths that guide light emitted from the LED lamps  43 A,  43 B, and  43 C to the top portion  305 T. 
     Since the three unit light guides  51 A,  51 B, and  51 C have the same structure, the structure of only the first unit light guide  51 A (light guide) will be described. The first unit light guide  51 A is a rod-like member made of transparent resin material and extending in an up-down direction. The first unit light guide  51 A has a base portion  52 , the end portion  53 , a body portion  54 , and a supporting member  55 . The base portion  52  is located at a lower end of a rod-like portion of the first unit light guide  51 A. Light emitted from the first LED lamp  43 A travels into the base portion  52 . The end portion  53  (light diffusing portion) is located at an upper end of the rod-like portion of the first unit light guide  51 A. The light is diffused outward from the end portion  53 . The body portion  54  (light guide path) forms a main body of the rod-like portion of the first unit light guide  51 A, and connects the base portion  52  to the end portion  53 . The supporting member  55  is connected to the lower end of the base portion  52 . 
     The body portion  54  has a substantially rectangular horizontal cross-section. In contrast, the supporting member  55  is a cylindrical body internally provided with a cavity  56  and having a diameter decreasing toward an upward position (see  FIG. 13  and  FIG. 14 ). The upper end of the supporting member  55  is integrally connected to the base portion  52  to hold the base portion  52 . The supporting member  55  is open at the lower end to allow the cavity  56  to be exposed. The cavity  56  has an inner diameter and a height that accommodates the first LED lamp  43 A. 
     The first and third unit light guides  51 A and  51 C each are provided with a retaining portion  57  jutting out of the front surface of the body portion  54  at a position near the upper end of the body portion  54 . The retaining portion  57  is a protrusion for positioning the light guide unit  50  in the up-down direction. The second unit light guide  51 B is provided with ridges  58  jutting from the front and back surfaces of the body portion  54  and extending in the up-down direction. The ridges  58  are protrusions for positioning the light guide unit  50  in the right-left direction. The third unit light guide  51 C is provided with ridges  59  jutting from the right side surface of the body portion  54  and extending in the up-down direction. The ridges  59  are protrusions for positioning the light guide unit  50  in the front-back direction. 
     In substantially the center of the body portions  54  in the up-down direction, one of the connecting ribs  50 L connects the first and second unit light guides  51 A and  51 B to each other, and the other of the connecting ribs  50 L connects the second and third unit light guides  51 B and  51 C to each other. The connecting ribs  50 L are each a plate-like member having a slit  50 S extending in the up-down direction. 
     As illustrated in  FIG. 9 , the light guide unit  50  is located on the back portion  403  of the printed circuit board  40 P such that the lower ends of the supporting members  55  are in contact with the mounting surface of the printed circuit board  40 P. The first, second, and third LED lamps  43 A,  43 B, and  43 C are contained in the respective cavities  56  of the light guide unit  50 . The partition plates  404  are positioned in the respective slits  50 S of the connecting ribs  50 L. With this configuration, the light guide unit  50  can be supported by using the mounting surface of the printed circuit board  40 P. At the same time, the light guide unit  50  can be positioned by using the partition plates  404  and the first, second, and third LED lamps  43 A,  43 B, and  43 C mounted on the printed circuit board  40 P. It is thus possible to improve work efficiency during manufacture and maintenance of the image forming apparatus  10 . 
       FIG. 11  is an enlarged perspective view of the operation section OP.  FIG. 12  is an enlarged perspective view of the status indicator  33 .  FIG. 13  is a cross-sectional view of the operation section OP.  FIG. 14  is an enlarged cross-sectional view of the status indicator  33  and its vicinity, and provides a further enlarged cross-sectional view of the end portion  53  of the first unit light guide  51 A in a dotted circle. As described above, the top portion  305 T of the protruding housing  305  is provided with the three grooves  307  formed by recessing parts of the top portion  305 T. Each of the grooves  307  has a bottom portion  308  and an opening  309  formed in the bottom portion  308 . 
     The printed circuit board  40 P is covered by the protruding housing  305 , with the mounting surface having the first, second, and third LED lamps  43 A,  43 B, and  43 C thereon facing upward. The three openings  309  of the grooves  307  are located directly above the respective mounting positions of the LED lamps  43 A,  43 B, and  43 C on the printed circuit board  40 P. The end portions  53  of the first, second, and third unit light guides  51 A,  51 B, and  51 C fitted onto the LED lamps  43 A,  43 B, and  43 C are exposed outwardly through the openings  309 , whereas the body portions  54  and other lower parts are covered by the protruding housing  305 . The end portions  53  protrude above the bottom portions  308 , but are contained in the grooves  307 . With this configuration, where the end portions  53  (light diffusing portions) are positioned inside the grooves  307 , the end portions  53  can be protected from external force. Additionally, since light emitted from the end portions  53  can be diffused through the openings  309  of the grooves  307 , it is possible to improve visibility of the illumination information. 
     Referring to  FIG. 14 , the end portion  53  of the first unit light guide  51 A has first and second cut surfaces  531  and  532  for refracting light and diffusing the light outwardly. The cut surfaces  531  and  532  are inclined surfaces formed by cutting the upper end of the body portion at an angle. With the cut surfaces  531  and  532 , the end portion  53  has a mountain-like cross-sectional shape with a peak  533  in the front-back direction. The base portion  52  and a top portion  43 T of the mold of the LED lamp unit  43  face each other, with a small gap therebetween. The supporting member  55  is connected to the outer surface of the base portion  52 , and the periphery of the first LED lamp  43 A is surrounded by the cylindrical wall of the supporting member  55 . The same applies to the second and third unit light guides  51 B and  51 C. 
     Light emitted from the first LED lamp  43 A travels from the base portion  52  into the first unit light guide  51 A. The incident light propagates through the body portion  54  to reach the end portion  53 . Then, the light is diffused outward from the end portion  53 . The diffused light includes light L 1  that has passed through the peak  533  and its vicinity and emitted upward, light L 2  that has been refracted (or reflected) by the second cut surface  532  and emitted from the first cut surface  531 , and light L 3  that has been refracted (or reflected) by the first cut surface  531  and emitted from the second cut surface  532 . Obviously, the diffused light includes light that has been refracted by the first cut surface  531  and emitted from the first cut surface  531 , and light that has been refracted by the second cut surface  532  and emitted from the second cut surface  532 . 
     As described above, light that has reached the end portion  53  is not only emitted from the peak  533  and its vicinity, but is also diffused circumferentially by being refracted by the first and second cut surfaces  531  and  532 . In the present specification, reflection is described as a mode of refraction. Since the first and second cut surfaces  531  and  532  face the flat bottom portion  308  of each of the grooves  307 , it is possible to provide a wide angle of view from the direction facing the cut surfaces  531  and  532 . Additionally, since the end portions  53 , which serve as light diffusing portions, are located near the top portion  305 T of the protruding housing  305 , the illumination of the end portions  53  can be easily viewed by the user from any direction relative to the image forming apparatus  10 . 
     As illustrated in  FIG. 13  and  FIG. 14 , the retaining portion  57  of the first unit light guide  51 A (or third unit light guide  51 C) is pressed by a pressing portion  305 P inside the protruding housing  305 , with the light guide unit  50  internally assembled to the protruding housing  305 . Thus, the up-down movement of the light guide unit  50  is regulated by the pressing portion  305 P and the back portion  403  of the printed circuit board  40 P. Although not shown in the drawings, the protruding housing  305  is internally provided with engaging portions that engage with the ridges  58  on the second unit light guide  51 B and the ridges  59  on the third unit light guide  51 C. This regulates the movement of the light guide unit  50  in the right-left direction and the front-back direction. 
     As described above, in an embodiment, light emitted from the first, second, and third LED lamps  43 A,  43 B, and  43 C passes through the body portions  54  of the unit light guides  51 A,  51 B, and  51 C of the light guide unit  50  and is guided to the end portions  53  serving as light diffusing portions. The light guide unit  50  is mostly contained inside the protruding housing  305 . However, since the end portions  53  are exposed outwardly through the openings  309  in the top portion  305 T of the protruding housing  305 , light can be diffused outwardly from the end portions  53 . Since the top portion  305 T protrudes upwardly above the top surface  11 T of the body housing  11 , light emitted from the end portions  53  can be easily viewed from any direction relative to the image forming apparatus  10 . 
     Through the use of the light guide unit  50 , the number of substrates to be used can be reduced. Specifically, if the LED lamp unit  43  is located at the top portion  305 T of the protruding housing  305 , a substrate for mounting the LED lamp unit  43  needs to be placed immediately below the top portion  305 T. Since it is difficult to secure a space near the top portion  305 T, the substrate has to be a dedicated substrate specifically designed for mounting the LED lamp unit  43 . This results in an increase in the number of substrates. However, in an embodiment, where light is guided by the light guide unit  50  to the top portion  305 T, the LED lamp unit  43  can be mounted on the printed circuit board  40 P where other electronic devices (e.g., the key switches  41  and the liquid-crystal display panel  42 ) are mounted. This means that the LED lamp unit  43  does not require a dedicated substrate. Since the unit light guides  51 A,  51 B, and  51 C can be formed by simple linear rod-like members, it is possible to simplify the structure. 
     An electrical configuration of the image forming apparatus  10  will now be described.  FIG. 15  is a block diagram illustrating an electrical configuration of the image forming apparatus  10 . The image forming apparatus  10  includes a controller  60  that controls the overall operation of the image forming section  13  and other components of the image forming apparatus  10 . The controller  60  includes a central processing unit (CPU), a read only memory (ROM) that stores control programs, and a random access memory (RAM) that is used as a work area for the CPU. In addition to the components described with reference to  FIG. 1  to  FIG. 14 , the image forming apparatus  10  includes an interface (I/F)  71 , an image memory  72 , a jam sensor  73 , a toner sensor  74 , and a sheet sensor  75 . 
     The I/F  71  is an interface circuit for realizing data communication with an external device. For example, the I/F  71  not only generates a communication signal in accordance with a network communication protocol for connecting the image forming apparatus  10  to the external device, but also converts a communication signal from the network into data having a format that can be processed by the image forming apparatus  10 . A print instruction signal transmitted from a personal computer or the like is given through the I/F  71  to the controller  60 , whereas image data is transmitted through the I/F  71  and stored in the image memory  72 . The image memory  72  temporarily stores print image data given from an external device, such as a personal computer. 
     The jam sensor  73  is formed, for example, by a photo-interrupter. The jam sensor  73  is placed at an appropriate position in the sheet conveying path  111  and detects a jam of a sheet fed along the sheet conveying path  111 . The toner sensor  74  is formed, for example, by a magnetic sensor mounted on the wall surface of each of the toner containers  15 M,  15 C,  15 Y, and  15 Bk. The toner sensor  74  outputs an electric signal based on the amount of toner remaining in the container. The sheet sensor  75  is formed, for example, by a light reflective sensor positioned to face the paper feed tray  121 . The sheet sensor  75  outputs an electric signal based on the presence or absence of a sheet in the paper feed tray  121 . 
     In the controller  60 , the CPU executes a control program stored in the ROM to control the operation of each component of the image forming apparatus  10  for image formation. In an embodiment, for controlling illumination of the LED lamp unit  43 , the controller  60  further includes a data-communication control unit  61 , a status-information acquiring unit  62 , and an illumination control unit  63 . 
     The data-communication control unit  61  controls the connection with an external device or network through the I/F  71 , and controls data communication with the external device through the I/F  71 . 
     The status-information acquiring unit  62  receives an electric signal outputted from the jam sensor  73 , the toner sensor  74 , or the sheet sensor  75  to detect whether there is a sheet jam, toner has run out, or sheets have run out. That is, the status-information acquiring unit  62  acquires status information of the image forming apparatus  10  based on the information related to image formation received from various sensors. 
     The illumination control unit  63  controls the illumination of the LED lamp unit  43  (first, second, and third LED lamps  43 A,  43 B, and  43 C). For controlling the illumination, the illumination control unit  63  refers to a data-communication control status of the data-communication control unit  61 , and status information acquired by the status-information acquiring unit  62 . For example, the first LED lamp  43 A is controlled to blink at predetermined intervals while image data is being received from an external device through the I/F  71 . The second LED lamp  43 B is controlled to illuminate when the image forming apparatus  10  is connected to a predetermined network (i.e., when the image forming apparatus  10  is online). The third LED lamp  43 C is controlled to illuminate when the status-information acquiring unit  62  detects the occurrence of trouble in the apparatus, such as a sheet jam, toner has run out, or sheets have run out. 
     The user views the illumination status of the first, second, and third LED lamps  43 A,  43 B, and  43 C of the status indicator  33  to recognize the status information of the image forming apparatus  10 . As described above, light emitted from the LED lamps  43 A,  43 B, and  43 C is passed through the light guide unit  50  and diffused from the top portion  305 T of the protruding housing  305  higher than the top surface  11 T of the body housing  11 . Therefore, the user can easily view the status indicator  33  from any direction. The user can thus reliably recognize the status information indicated by the illumination of the LED lamps  43 A,  43 B, and  43 C. 
     Although an embodiment of the present invention has been described in detail, the present invention is not limited to this. For example, the embodiment of the present invention may be modified as described below. 
     (1) In the embodiment described above, the light guide unit  50  (body portion  54 ) has been described as a light guide path. Alternatively, the light guide path may be a flexible light guide, such as an optical fiber. In this embodiment, an optical component having cut surfaces similar to those of the end portion  53  is provided, as a light diffusing portion, near the top portion  305 T of the protruding housing  305 . Then, the optical fiber is positioned to face an LED lamp at one end, and to face the lower surface of the optical component at the other end. 
     (2) Alternatively, the light guide path may be formed by a light guide space without specifically using a solid component. In this embodiment, a tubular member is used to define the light guide space, and a light reflective coating is applied to the inner wall of the tubular member. An opening at the lower end of the light guide space is positioned to face an LED lamp, and an opening at the upper end of the light guide space is positioned to face the lower surface of the optical component serving as a light diffusing portion. 
     (3) In the embodiment described above, the grooves  307  extending in the front-back direction have been described as notches at the top portion  305 T of the protruding housing  305 . Alternatively, the notches may be bowl-shaped notches, each having an opening at the bottom which allows protrusion of the corresponding end portion  53  of the light guide unit  50 . In this embodiment, the end portion  53  preferably has a quadrangular pyramid shape or a dome shape so that light can be substantially uniformly diffused in the circumferential direction. 
     (4) In the embodiment described above, the end portions  53  serving as light diffusing portions are located in the top portion  305 T of the protruding housing  305 . As long as the visibility of the image forming apparatus  10  from its surroundings is ensured, the light diffusing portions may be located near the top portion  305 T, not in the top portion  305 T. In the embodiment above, the top portion  305 T formed by a convex curved surface has been described as an example. However, the top portion of the protruding housing may be a flat surface. In other words, for example, the protruding housing may be in the shape of a trapezoid or a rectangular parallelepiped. 
     (5) In the embodiment above, the LED lamp unit  43  has been described as a light source. However, the light source is not particularly limited, and may be an incandescent lamp, an electroluminescent (EL) lamp, or other known small light sources. 
     The present disclosure is not to be limited in terms of the particular embodiments described in this application, which are intended as illustrations of various aspects. Many modifications and variations can be made without departing from its spirit and scope, as will be apparent to those skilled in the art. Functionally equivalent apparatuses within the scope of the disclosure, in addition to those enumerated herein, will be apparent to those skilled in the art from the foregoing descriptions. Such modifications and variations are intended to fall within the scope of the appended claims.