Abstract:
An image forming device including a casing having a front wall formed with a first opening and an upper wall continuous to the front wall and formed with a second opening. The first and second openings together form a single opening. The device further includes a door for covering the single opening, a belt unit, and a guide member. The belt unit includes first and second rollers, and a conveyer belt. The drawer is configured to accommodate a plurality of cartridges. The guide member is configured to movably guide the drawer. The first roller is disposed nearer to the single opening than the second roller to the single opening. In a state where the door is opened and the drawer is inside the casing, one of the plurality of cartridges closest to the door is detachably attachable to the drawer through the single opening.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a continuation of co-pending U.S. patent application Ser. No. 13/747,975 filed Jan. 23, 2013, which is a continuation of U.S. application Ser. No. 13/274,273 filed Oct. 14, 2011, now U.S. Pat. No. 8,401,427 issued Mar. 19, 2013, which is a continuation of U.S. application Ser. No. 13/105,076 filed May 11, 2011, now U.S. Pat. No. 8,064,794 issued Nov. 22, 2011, which is a continuation of U.S. application Ser. No. 12/781,568 filed May 17, 2010, now U.S. Pat. No. 7,962,062, issued Jun. 14, 2011, which is a continuation of Ser. No. 11/401,295, filed Apr. 11, 2006, which is now U.S. Pat. No. 7,747,190, issued Jun. 29, 2010, which claims priority from Japanese Patent Application No. 2005-113104 filed Apr. 11, 2005, the entire content of which is incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The disclosure relates to an electrographic image forming device such as a laser printer. 
     BACKGROUND 
     U.S. Pat. Nos. 5,182,595 and 5,210,573 disclose a laser printer having a main body and a cartridge. A plurality of image forming units are provided within the cartridge. The cartridge is drawn out from the main body so that a user can execute an inspection and maintenance of the image forming units and replacement of parts in the image forming units. 
     SUMMARY 
     It is conceivable that operations such as inspection of the image forming units are executed in the state where the cartridge is drawn out from the main body to the maximum so that the plurality of image forming units are exposed outside. However, when the cartridge is drawn out from the main body by a large amount, the cartridge largely projects outwards. Moreover, the center of gravity of the overall device moves towards the drawing side, allowing the device to be easily tilted. Thus, it will be difficult to perform operations such as inspection and replacement. 
     In view of the foregoing, it is an object of the invention to provide an image forming device capable of improving operability in making operations such as inspection, maintenance and replacement of image forming units. 
     In order to attain the above and other objects, the invention provides an image forming device of electronic photography including a casing, a door, a belt unit, a drawer, and a guide member. The a casing includes a front wall formed with a first opening, and an upper wall continuous to the front wall and formed with a second opening. The first opening and the second opening together forms a single opening. The door is configured to cover the single opening. The belt unit is disposed in the casing and includes a first roller, a second roller, and a conveyer belt stretched over the first roller and the second roller. The drawer is coupled to the casing and is configured to accommodate a plurality of cartridges. The guide member is disposed in the casing and is configured to movably guide the drawer. The first roller is disposed nearer to the single opening of the casing than the second roller to the single opening. In a state where the door is opened and the drawer is inside the casing, one of the plurality of cartridges closest to the door is detachably attachable to the drawer through the single opening. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings: 
         FIG. 1  is a schematic side sectional view showing the state where a drawer is located at a storage position in a laser printer in accordance with a first embodiment of the invention; 
         FIGS. 2(A) and 2(B)  are schematic sectional views of a guide groove when viewed from the side of an opening, wherein  FIG. 2(A)  is a schematic sectional view of the guide groove in a state where an engaging member is located at a release position and  FIG. 2(B)  is a schematic sectional view of the guide groove in a state where the engaging member is located at an engagement position; 
         FIG. 3  is a schematic side sectional view of the drawer and guide groove in a state where the drawer is located at a storage position; 
         FIG. 4  is a schematic side sectional view of the drawer and guide groove in a state where the drawer is located at a first drawing position; 
         FIG. 5  is a schematic side sectional view of the laser printer in the state where the drawer is located at the first drawing position; 
         FIG. 6  is a schematic side sectional view of the laser printer in a state where the drawer is located at a second drawing position; 
         FIG. 7  is a schematic side sectional view of the laser printer in a state where the drawer is located at a third drawing position; 
         FIG. 8  is a schematic side sectional view of the laser printer in a state where the drawer is located at a fourth drawing position; 
         FIG. 9  is a schematic side sectional view of the drawer and guide groove in a state where the drawer is detached; 
         FIG. 10  is a schematic side sectional view of the laser printer in the state where the drawer is detached; 
         FIG. 11  is a schematic side sectional view of a laser printer in accordance with a second embodiment; and 
         FIG. 12  is a schematic side sectional view of the drawer and guide groove in a state where the drawer is located at the third drawing position according to the second embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     An image forming device according to embodiments of the invention will be described while referring to the accompanying drawings wherein like parts and components are designated by the same reference numerals to avoid duplicating description. 
     &lt;First Embodiment&gt; 
     A tandem-type color laser printer according to a first embodiment will be described with reference to  FIGS. 1 to 10 . 
     (Overall Configuration of the Laser Printer) 
       FIG. 1  is a schematic side sectional view of the laser printer  1 . 
     The terms “upward”, “downward”, “upper”, “lower”, “above”, “below”, “beneath”, “right”, “left”, “front”, “rear” and the like will be used throughout the description assuming that the laser printer  1  is disposed in an orientation in which it is intended to be used. In use, the laser printer  1  is disposed as shown in  FIG. 1 . 
     The laser printer  1  has a main body casing  2 . A sheet feed cassette  4  is provided on the bottom of the main body casing  2  and can be drawn out of the main body casing  2  forward in the horizontal direction. Sheets of paper or other kinds of sheet material can be mounted in the sheet feed cassette  4 . A paper feed roller  5  is mounted in the main body casing  2  at a front upper end of the sheet feed cassette  4 . Sheets  3  mounted on the sheet feed cassette  4  are sent upwards one at a time by the paper feed roller  5  from the sheet feed cassette  4  along a conveyance path that is represented by a chain line in  FIG. 1 . 
     A pair of conveyance rollers  6  are provided above the sheet feed roller  5 . The sheet  3  is conveyed by the rollers  6  to a conveying belt  7 . The conveying belt  7  is located at the rear of the conveyance rollers  6 . The conveying belt  7  is of an endless shape and is stretched on a pair of support rollers  8  and  8 . The conveying belt  7  is inclined upwardly toward the front end along a predetermined drawing direction D which will be described later. The conveying belt  7  is for conveying the sheet  3  on its top face in a rearward direction. 
     The main body casing  2  is formed with an opening  9 . The opening  9  is formed over a region extending from the upper portion of the front surface of the main body casing  2  to the front end of the upper surface of the main body casing  2 . A cover  10  is mounted on the main body casing  2  to cover the opening  9 . The cover  10  is openable and closable. 
     The main body casing  2  accommodates a drawer  11  therein. As shown in  FIG. 1 , the drawer  11  can be stored within the main body casing  2  at a storage position above the conveying belt  7 . A user can open the cover  10 , and pull the drawer  11  from the storage position in a direction parallel to the top face of the conveying belt  7 , that is, in the drawing direction D. Thus, the user can draw the drawer  11  obliquely upwardly toward the front. As a result, the drawer  11  is drawn out of the main body casing  2  through the opening  9 . After the drawer  11  is drawn out of the main body casing  2 , the user can press the drawer  11  in a storing direction S that is opposite to the drawing direction D. Thus, the drawer  11  can return back to the storage position in the main body casing  2 . 
     The drawer  11  is of an elongated box shape, whose top and bottom faces are partially opened. The drawer  11  is kept in an orientation, in which the drawer  11  is inclined upwardly toward the front, with its bottom face being parallel to the top face of the conveying belt  7 . A handle  12  is provided on the front face of the drawer  11 . A user grips the handle  12  to draw the drawer  11  from the main body casing  2 . 
     The drawer  11  is oriented with its elongated direction being along the drawing direction D. the drawer  11  holds therein four process cartridges  13 Y,  13 M,  13 C and  13 K that are aligned in the longitudinal direction, that is, in the drawing direction D. The process cartridges  13 Y,  13 M,  13 C and  13 K correspond to yellow, magenta, cyan and black, respectively. Each process cartridge  13 : has a toner case  14  for storing a toner therein; a photosensitive drum  15  for carrying an electrostatic latent image; and a developing device  19  for developing the electrostatic latent image into a visible toner image. The developing device  19  includes: a supply roller  19   a  for supplying toner from the toner case  14  to a developing roller  19   b;  and the developing roller  19   b  for developing the electrostatic latent image carried on the photosensitive drum  15  into a visible toner image. Each process cartridge  13  is mounted in the drawer  11 , with its photosensitive drum  15  being exposed through the opening section of the bottom face of the drawer  11  and facing the top face of the conveying belt  7 . Each process cartridge  13  can be detached from the drawer  11  by lifting up the process cartridge  13  through the opening section of the top face of the drawer  11 . 
     A scanner  16  is mounted in the main body casing  2  at a location above the drawer  11 . The scanner  16  irradiates each photosensitive drum  15  with a laser light L corresponding to image data of a corresponding color to form a corresponding electrostatic latent image on the surface of the photosensitive drum  15 . The developing device  19  develops the electrostatic latent image into a visible toner image by using toner. The toner images carried on the photosensitive drums  15  are sequentially transferred onto a sheet of paper  3  as being superposed one on another, while the sheet of paper  3  is being conveyed on the top face of the conveying belt  7 . As a result, a full-color image is formed on the sheet of paper  3 . 
     A sheet of paper  3 , on which a full-color image has been formed as described above, is then conveyed to a fixing part  17 , which is mounted in the main body casing  2  at the rear of the conveying belt  7 . The fixing part  17  thermally fixes the full-color image onto the sheet  3 . After having passed through the fixing part  17 , the sheet  3  is discharged out of the main body casing  2 . The sheet  3  may be discharged to the rear of the main body casing  2  or on a sheet output tray  18  that is provided on the top face of the main body casing  2 . 
     (Engagement Structure of Drawer) 
     The main body casing  2  has a pair of side walls (right-side wall and left-side wall)  2 A that are disposed on the right-side and left-side of the main body casing  2 , respectively. When the drawer  11  is mounted in the laser printer  1 , the drawer  11  is located between the pair of opposite side walls  2 A in the widthwise direction (right-to-left direction) of the laser printer  1 . 
       FIGS. 2(A) and 2(B)  are schematic sectional views of a right-side end portion of the drawer  11  and a right-side wall  2 A viewed from the side of the opening  9 , that is, from the front side. 
     A pair of guide protrusions (right-side and left-side guide protrusions)  20  are formed on the lower ends of the right- and left-side surfaces of the drawer  11 . The guide protrusions  20  protrude outwardly in the widthwise direction from the drawer  11 . That is, the right-side guide protrusion  20  protrudes rightwardly from the drawer  11 , while the left-side guide protrusion  20  protrudes leftwardly from the drawer  11 . The right-side guide protrusion  20  is shown in  FIGS. 2(A) and 2(B) . Each guide protrusion  20  is elongated along the longitudinal direction of the drawer  11 , that is, along the drawing direction D of the drawer  11 . Each guide protrusion  20  has a bottom surface  20   a  and a top surface  20   b , both of which extend in the drawing direction D. 
     A guide groove  21  is formed on the inner side surface of each side wall  2 A. That is, a guide groove  21  is formed on the left-side surface of the right-side wall  2 A, and another guide groove  21  is formed on the right-side surface of the left-side wall  2 A. The guide groove  21  formed on the right-side wall  2 A is shown in  FIGS. 2(A) and 2(B) . The guide groove  21  extends parallel with the stretching direction of the conveying belt  7 . In other words, the guide groove  21  extends in the drawing direction D.  FIG. 3  is a schematic side sectional view showing the guide groove  21  formed on the right-side wall  2 A. The guide groove  21  has a floor surface  21   a  and a ceiling surface  21   b , both of which extend in the drawing direction D. 
     The guide protrusion  20  protruding from the right-side of the drawer  11  is fitted into the guide groove  21  on the right-side wall  2 A, while the guide protrusion  20  protruding from the left-side of the drawer  11  is fitted into the guide groove  21  formed on the left-side wall  2 A. The drawer  11  can move backward and forward along the guide grooves  21 , with the guide protrusions  20  moving along the guide grooves  21 . That is, the top surface  20   b  of each guide protrusion  20  slides against the ceiling surface  21   b  of the corresponding guide groove  21 , while the bottom surface  20   a  of each guide protrusion  20  slides against the floor surface  21   a  of the corresponding guide groove  21 . Thus, the drawer  11  is guided along the guide grooves  21  on the right- and left-side walls  2 A. The drawer  11  can be drawn out from the main body casing  2  and can be pressed into the main body casing  2 . 
     Each side wall  2 A is further formed with a bore  24 . The bore  24  is located in the vicinity of the front end of the side wall  2 A, near to the opening  9 . The bore  24  is elongated in a direction perpendicular to the drawing direction D. In other words, the bore  24  has a longitudinal axis that extends perpendicularly to the drawing direction D. The bore  24  is opened through the ceiling surface  21   b  of the guide groove  21  and is in fluid communication with the guide groove  21 . Thus, the bore  24  is connected to the guide groove  21  at the vicinity of the front end of the guide groove  21 . 
     An engaging member  22  is mounted inside the bore  24 . The engaging member  22  is movable along the longitudinal axis of the bore  24 . Thus, the engaging member  22  is capable of moving or displacing in the direction perpendicular to the guide groove  21 . As shown in  FIG. 3 , a tip end of the engaging member  22  is formed in the shape of a substantially semi-circular arc when viewed from the side. The engaging member  22  can move between an engagement position where its tip end protrudes in the guide groove  21  as shown in  FIG. 2(B)  and a release position where the tip end retracts from the guide groove  21  as shown in  FIG. 2(A) . 
     A coil spring  23  is also mounted in the bore  24  to urge the engaging member  22  along the longitudinal axis of the bore  24  in a direction toward the floor surface  21   a  of the guide groove  21 . In other words, the engaging member  22  is urged by the coil spring  23  in a direction from the release position toward the engagement position. 
     A front-end inclined surface  25  is formed at a front end of the top surface  20   b  of the guide protrusion  20 . The front-end inclined surface  25  slopes downwardly to the front. When the drawer  11  is located at the storage position shown in  FIG. 3 , the engaging member  22  located at the engagement position engages with the front-end inclined surface  25 . 
     Four engagement recesses  26 A to  26 D are formed on the top surface  20   b  of the guide protrusion  20 . The engagement recesses  26 A to  26 D are aligned at a regular interval along the drawing direction D on the top surface  20   b  of the guide protrusion  20 . The engaging member  22  can engage with each of the engagement recesses  26 A to  26 D. 
     Each of the engagement recesses  26 A to  26 D is substantially of a v-shaped cross-section viewed from the side. Each engagement recess  26 A,  26 B,  26 C, or  26 D has: a rear-side inclined surface  27 A which slopes downwardly toward the front; and a front-side inclined surface  27 B which slopes upwardly toward the front from the front end of the rear-side inclined surface  27 A. As shown in  FIG. 4 , an angle θB of greater than zero degree is defined between the front-side inclined surface  27 B and the top surface  20   b , and an angle θA of greater than zero degree is defined between the rear-side inclined surface  27 A and the top surface  20   b.    
     Now assume that an engaging force of an amount F 1  is exerted from the coil spring  23  to the engaging member  22  when the engaging member  22  is in the engagement position and is engaged with each engagement recess  26 A,  26 B,  26 C, or  26 D. Further assume that the slope of the floor surface  21   a  relative to the horizontal direction (an angle defined between the floor surface  21   a  and the horizontal) is θ 0  (greater than zero degree), that the total weight of the drawer  11  and all the process cartridges  13 Y- 13 K is m, and that the gravitational acceleration is g. According to the present embodiment, the values F 1 , θB, θ 0 , m, and g satisfy the following inequality (1):
 
 F 1≧{mg(sin θ0)}/(tan θ B )  (1)
 
     Accordingly, when the engaging member  22  is in engagement with each engagement recess  26 A,  26 B,  26 C, or  26 D, it is ensured that the engagement between the engaging member  22  and the engagement recess  26 A,  26 B,  26 C, or  26 D can prevent the drawer  11  from returning back to the storage position due to the weight of the drawer  11  and the process cartridges  13 Y- 13 K. In other words, it is ensured that the drawer  11  will not slide along the floor surface  20   a  downwardly to the rear, even if there is no friction between the bottom surface  20   a  of the guide protrusion  20  and the floor surface  21   a  of the guide groove  21 . 
     More specifically, if the values F 1 , θB, θ 0 , m, and g fail to satisfy the above inequality (1) and if there is no friction between the bottom surface  20   a  and the floor surface  21   a , even when the engaging member  22  is engaged with one of the engagement recesses  26 A- 26 D, the drawer  11  will slide along the floor surface  21   a  of the guide groove  21  downwardly to the rear due to the weight of the drawer  11  and the process cartridges  13 Y- 13 K, while allowing the engaging member  22  to slide along the front-side inclined surface  27 B upwardly to the front and to be disengaged from the engagement recess  26 A,  26 B,  26 C, or  26 D. 
     Additionally, according to the present embodiment, the angle θA formed between the rear-side inclined surface  27 A and the top surface  20   b  is smaller than the angle θB formed between the front-side inclined surface  27 B and the top surface  20   b . In other words, the slope of the rear-side inclined surface  27 A relative to the top surface  20   b  is smaller than the slope of the front-side inclined surface  27 B relative to the top surface  20   b.    
     In the state where the engaging member  22  is in engagement with one of the engagement recesses  26 A to  26 D, when the user presses or pushes the drawer  11  in the storing direction S, the engagement between the engaging member  22  and the engagement recess  26 A,  26 B,  26 C, or  26 D exhibits a first type of engaging force against the user&#39;s action of pushing the drawer  11  in the storing direction S. Similarly, in the state where the engaging member  22  is in engagement with one of the engagement recesses  26 A to  26 D, when the user pulls or draws the drawer  11  in the drawing direction D, the engagement between the engaging member  22  and the engagement recess  26 A,  26 B,  26 C, or  26 D exhibits a second type of engaging force against the user&#39;s action of drawing the drawer  11  in the drawing direction D. Because the angle θA is smaller than the angle θB, the amount of the second type of engaging force against the user&#39;s drawing action is smaller than the amount of the first type of engaging force against the user&#39;s pushing action. 
     A rear-end inclined surface  28  is formed at a rear end of the top surface  20   b  of the guide protrusion  20 . The rear-end inclined surface  28  slopes downwards toward the rear. As described later, the rear-end inclined surface  28  guides the engaging member  22  when the rear end of the guide protrusion  20  is fitted into the front end of the guide groove  21 . 
       FIGS. 3, 4 and 9  show the positional relationship between the drawer  11  and guide groove  21  in distinct positions.  FIGS. 5 to 8 and 10  show how the position of the drawer  11  is successively varied. 
     In order to draw the drawer  11  out of the main body casing  2  from the storage position shown in  FIGS. 1 and 3 , first, the user opens the cover  10  and then grips the handle  12  and pulls the drawer  11  forward in the drawing direction D. As a result, the engaging member  22  that is originally engaged with the front-end inclined surface  25  as shown in  FIG. 3  is guided by the front-end inclined surface  25 , moves to the release position while compressing the coil spring  23  and finally runs onto the top surface  20   b  of the guide protrusion  20  as shown in  FIG. 2(A) . 
     Subsequently, when the engaging member  22  arrives at the foremost engagement recess  26 A, the coil spring  23  is restored to the original state, and the engaging member  22  is displaced from the release position to the engagement position and engages with the engagement recess  26 A at its tip end as shown in  FIGS. 2(B)  and  4 . The engaging force of the engaging member  22  against the engagement recess  26 A is sufficiently large that prevents the drawer  11  from returning back to the storage position due to the total weight of the drawer  11  and all the process cartridges  13 Y- 13 K. Accordingly, when the engaging member  22  reaches the engagement recess  26 A, if the user stops his/her drawing operation, the drawer  11  will be held at a first drawing position shown in  FIG. 5  without returning to the storage position. At the first drawing position, the foremost process cartridge  13 Y is exposed to the outside. The user can inspect and perform maintaining operation on the process cartridge  13 Y as well as detach the process cartridge  13 Y from the drawer  11 . On the contrary, since the other process cartridges  13 M,  13 C and  13 K are still located within the main body casing  2 , not exposed, inspection and maintenance of the cartridge  13 M,  13 C or  13 K cannot be made. 
     When the drawer  11  is further drawn from the first drawing position, the engaging member  22  is guided by the rear-side inclined surface  27 A of the engagement recess  26 A and is displaced from the engagement position to the release position. Subsequently, when the engaging member  22  arrives at the engagement recess  26 B located at the second position and engaged therewith, the drawer  11  is engaged at a second drawing position shown in  FIG. 6 . At the second drawing position, since the front two process cartridges  13 Y and  13 M are exposed to the outside, inspection and maintenance of these cartridges can be carried out. 
     Similarly, when the drawer  11  is further drawn out from the second drawing position, the engaging member  22  disengages from the engagement recess  26 B. When the engaging member  22  engages with the engagement recess  26 C located at the third position, the drawer  11  is held at a third drawing position shown in  FIG. 7 . At the third drawing position, since the front three process cartridges  13 Y,  13 M and  13 C are exposed to the outside, inspection and maintenance of these cartridges can be carried out. 
     When the drawer  11  is further drawn out from the third drawing position, the engaging member  22  disengages from the engagement recess  26 C. When the engaging member  22  engages with the engagement recess  26 D located at the fourth position, the drawer  11  is held at a fourth drawing position shown in  FIG. 8 . At the fourth drawing position, all of the process cartridges  13 Y to  13 K are exposed to the outside, and therefore inspection and maintenance of all of these cartridges can be performed. 
     Thus, by drawing out the drawer  11  in this manner, the drawer  11  sequentially reaches the first through fourth drawing positions, while moving in the drawing direction D. While the drawer  11  sequentially reaches the first through fourth drawing positions, the process cartridges  13 Y to  13 K are sequentially exposed to the outside. Each time the drawer  11  reaches one of the first through fourth drawing positions, the drawer  11  is engaged at the subject drawing position. Thus, by drawing out the drawer  11  to the position where one or more process cartridges  13 Y to  13 K desired to be inspected are exposed and engaging the drawer  11  at the position, the drawing amount can be minimized. 
     In order to return the drawer  11  from each of the first through fourth drawing positions back to the storage position, the user presses the drawer  11  in the storing direction S toward the storage position. As a result, the engaging member  22  that is now in engagement with the corresponding engagement recess  26 A,  26 B,  26 C, or  26 D is shifted to the release position along the front-side inclined surface  27 B so as to release the engagement from the engagement recess  26 A,  26 B,  26 C, or  26 D. The drawer  11  moves in the storing direction S as being pressed by the user. Even when the engaging member  22  engages with another engagement recess  26 B,  26 C, or  26 D while the drawer  11  is moving in the storing direction S, the engagement is released again when the user continues his/her pressing operation. Therefore, the drawer  11  can successfully reach the storage position of  FIGS. 1 and 3 . 
     In order to completely detach the drawer  11  from the main body casing  2 , the user draws the drawer  11  further forwards from the fourth drawing position shown in  FIG. 8 . As a result, the guide protrusion  20  is separated from the guide groove  21  as shown in  FIGS. 9 and 10 . The drawer  11  is completely detached from the main body casing  2 . In this state, the user can cope with a sheet jam within the main body casing  2 . 
     To attach the detached drawer  11  back to the main body casing  2 , the user fits the guide protrusion  20  into the guide groove  21 . It is noted that when the drawer  11  is in the detached state, the engaging member  22  protrudes inside the guide groove  21  as shown in  FIG. 9 . When the user fits the rear end of the guide protrusion  20  into the front end of the guide groove  21 , the engaging member  22  is guided by the rear-end inclined surface  28  to retract from the guide groove  21  to the release position. Accordingly, the guide protrusion  20  can be smoothly fitted into the guide groove  21 . Then, the user presses the drawer  11  in the storing direction S into the main body casing  2 . 
     As described above, in this embodiment, when desiring to perform inspection and maintenance as well as replacement of desired one or more process cartridge  13 Y to  13 K, the drawer  11  is drawn to the drawing position where the desired one or more process cartridge  13 Y to  13 K is exposed, and the drawer  11  is held at the drawing position by the engagement between the engaging member  22  and the corresponding engagement recess  26 A to  26 D. Accordingly, the drawing amount can be minimized. Thus, the protruding amount of the drawer  11  can be controlled. Moreover, the laser printer  1  can be stabilized due to reduction in lateral movement of the center of gravity thereof. Operability is improved. 
     When desiring to replace some toner case  14  with a new one, the drawer  11  is drawn to the drawing position where at least a process cartridge  13 Y,  13 M,  13 C, or  13 K that has the desired toner case  14  is exposed, and the drawer  11  is engaged to the main body casing  2  at the subject drawing position. Thus, the drawing amount can be minimized and operability can be improved. 
     Engagement and disengagement of the engaging member  22  to and from the engagement recess  26 A,  26 B,  26 C, or  26 D is executed in association with the drawing operation of the drawer  11 . Operability is more excellent compared to the case where an additional operation were required to engage and disengage the engaging member  22  to and from the engagement recess  26 A,  26 B,  26 C, or  26 D separately from the drawing operation of the drawer  11 . 
     The plurality of engagement recesses  26 A to  26 D are aligned in the drawing direction D on the guide protrusion  20 . The engaging member  22  can be displaced between the engagement position and release position. The engaging member  22  is urged by the coil spring  23  from the release position toward the engagement position. The combination of the engagement recesses  26 A to  26 D and the engaging member  22  has a simple configuration. 
     Engagement of the engaging member  22  with the front-end inclined surface  25  of the guide protrusion  20  can prevent the drawer  11  from being improperly drawn out of the storage position. Since the engaging member  22  properly holds the drawer  11  at the storage position, the configuration of the entire device  1  can be simplified. 
     Since the drawer  11  is drawn out diagonally upwards relative to the main body casing  2 , lateral movement of the center of gravity is reduced, compared to the case where the drawer  11  is drawn out in the horizontal direction. This further stabilizes the overall device  1 . 
     Moreover, the engaging force of the engaging member  22  against the engagement recesses  26 A to  26 D is sufficiently large that can prevent the drawer  11  from returning to the storage position due to the weight of the drawer  11  and the process cartridges  13 Y- 13 K. Accordingly, when the drawer  11  is at the drawing position, the drawer  11  is prevented from returning to the storage position due to the weight of the drawer  11  and process cartridges  13 . 
     &lt;Second Embodiment&gt; 
     Next, referring to  FIGS. 11 and 12 , a second embodiment of the invention will be described. 
     A laser printer  30  according to the second embodiment is the same as the laser printer  1  according to the first embodiment except for the points described below. 
       FIG. 11  is a schematic side sectional view of the laser printer  30 , and  FIG. 12  is a schematic side sectional view of the drawer  11  and guide groove  21  in the state where the drawer  11  is drawn out to the third drawing position. 
     In the laser printer  30  of this embodiment, the guide groove  21  extends in the horizontal direction, and therefore the drawer  11  is drawn out in the horizontal direction with respect to the main body casing  2 . In other words, according to the present embodiment, the drawing direction D and the storing direction S are defined along the horizontal. 
     As shown in  FIG. 12 , the guide protrusion  20  of the present embodiment is formed with four engagement recesses  31 A to  31 D in place of the four engagement recesses  26 A to  26 D in the first embodiment. Each engagement recess  31 A,  31 B,  31 C, or  31 D has a rear-side inclined surface  32 A and a front-side inclined surface  32 B. A slope of the rear-side inclined surface  32 A relative to the top surface  20   b  is larger than a slope of the front-side inclined surface  32 B relative to the top surface  20   b . More specifically, an angle φA (greater than zero degree) defined between the rear-side inclined surface  32 A and the top surface  20   b  is greater than an angle φB (greater than zero degree) defined between the front-side inclined surface  32 B and the top surface  20   b.    
     In the state where the engaging member  22  is in engagement with one of the engagement recesses  31 A to  31 D, when the user presses or pushes the drawer  11  in the storing direction S, the engagement between the engaging member  22  and the engagement recess  31 A,  31 B,  31 C, or  31 D exhibits a first type of engaging force against the user&#39;s action of pushing the drawer  11  in the storing direction S. Similarly, in the state where the engaging member  22  is in engagement with one of the engagement recesses  31 A to  31 D, when the user pulls or draws the drawer  11  in the drawing direction D, the engagement between the engaging member  22  and the engagement recess  31 A,  31 B,  31 C, or  31 D exhibits a second type of engaging force against the user&#39;s action of drawing the drawer  11  in the drawing direction D. Because the angle φA is greater than the angle φB, the amount of the first type of engaging force against the user&#39;s pushing action is smaller than the amount of the second type of engaging force against the user&#39;s drawing action. Thus, an operating force required for disengaging the engaging member  22  from the engagement recess  31 A,  31 B,  31 C, or  31 D by pushing the drawer  11  to the storage position is smaller than an operating force required for disengaging the engaging member  22  from the engagement recess  31 A,  31 B,  31 C, or  31 D by drawing the drawer  11  in the drawing direction D. Therefore, the drawer  11  can be moved with a smaller force during the pressing than during the drawing, resulting in improvement in operability. 
     While the invention has been described in detail with reference to the above-described embodiments thereof, it would be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention. 
     In the above description, each process cartridge  13  can be detached from the drawer  11 . However, each process cartridge  13  may be fixed to the drawer  11  and may not be detached from the drawer  11 . 
     In the above description, the entire part of each process cartridge  13  can be detached from the drawer  11 . However, only a part of the process cartridge  13  may be detached from the drawer  11 . For example, only a part of the process cartridge  13  that includes the toner case  14  may be detached from the drawer  11 . Only the toner caser  14  may be detached from the drawer  11 . 
     In the above description, the engaging member  22  is engaged to and disengaged from the engagement recesses  26 A to  26 D or the engagement recesses  31 A to  31 D in association with the drawing or pushing action of the drawer  11 . However, engagement and disengagement of the engaging member  22  to and from the engagement recesses  26 A to  26 D or the engagement recesses  31 A to  31 D may be carried out by a separate operation other than the movement of the drawer  11 . For example, an operating part for operating the engaging member  22  may be provided on the drawer  11  side or on the main body  2  side. The user can move the drawer  11  while operating the operating part to maintain the engaging member  22  at the release position. 
     In the above description, the engaging member  22  is provided on the main body casing  2  side, and the engagement recesses  26 A to  26 D or the engagement recesses  31 A to  31 D are provided on the drawer  11  side. However, the engaging member  22  may be provided on the drawer  11  side, and the engagement recesses  26 A to  26 D or the engagement recesses  31 A to  31 D may be provided on the main body casing  2  side. 
     In the above description, the bore  24  extends perpendicularly to the predetermined drawing direction D. However, the bore  24  may not extend perpendicularly to the predetermined drawing direction D as long as the bore  24  extends in a direction intersecting with the predetermined drawing direction D. In this case, the engaging member  22  and coil spring  23  are provided in the bore  24  so that the coil spring  23  urges the engaging member  22  along the longitudinal axis of the bore  24 , that is, in the direction intersecting the drawing direction D. 
     The engaging force F 1  may be smaller than the value of {mg(sin θ 0 )}/(tan θB) when there is some amount of friction between the bottom surface  20   a  of the guide protrusion  20  and the floor surface  21   a  of the guide groove  21 .