Abstract:
An image-forming apparatus is of upright construction and includes a medium-feeding section, an image-forming section, and stacker. The medium-feeding section accommodates a stack of print medium in an upright origatation. The image-forming section is disposed in vertical alignment with the medium-feeding section, and prints information on a page of the print medium fed from the medium-feeding section. The stacker is disposed in vertical alignment with the image forming section, and receives the printed page of the print medium and accommodates the page of the print medium in an upright orientation. The image-forming section is above the medium feeding section and the stacker is above the image-forming section. The stacker may have a sensor that generates a detection signal of the print medium when the print medium is received therein. The detection signal is used to provide a visible indication, i.e., an alarm that informs the user of the presence and absence of the print medium.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to art image-forming apparatus. 
     2. Description of the Related art 
     An image-forming apparatus for personal use, including a copying machine and a printer, is usually of small size and is placed on a desk. Such an apparatus incorporates a sheet feeder that holds a stack of print medium such as paper in an inclined position. The paper is fed from the sheet feeder and then information is printed on the paper. The paper is then discharged to a paper stack at either the front end or the rear end of the image-forming apparatus. 
     An image-forming apparatus for office use is of large size and incorporates a paper-feeding section having paper cassettes that hold a stack of print medium lying horizontal, or has paper cassettes that hold a stack of print medium therein and obliquely project outwardly from the main body of the apparatus. Such paper cassettes usually take up as large an area as one complete desk or a half of it. 
     An apparatus for personal use occupies a considerable area on the desk, leaving only a limited space where the user can do deskwork. This makes the clerical work inefficient. A large-size apparatus occupies a relatively large area at a corner in the office, making the remaining office space small. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention was made in view of the aforementioned drawbacks of the conventional apparatus. An image-forming apparatus is of upright construction. A medium-feeding section accommodates a stack of print medium. An image-forming section is disposed in vertical alignment with the medium-feeding section, the image-forming section printing information on a page of the print medium fed from the medium-feeding section. A stacker is disposed in vertical alignment with the image-forming section. The stacker receives the page of the print medium that has been printed and accommodates the page of the print medium in an upright orientation. 
     The image-forming section is above the medium-feeding section and the stacker is above the image-forming section. 
     The stacker may have a visible indicator by which a user can detect the presence and absence of the print medium. 
     The stacker may have a sensor that generates a detection signal when the print medium is received therein. The visible indication is an alarm that informs the user of the presence and absence of the print medium in the stacker according to the detection signal. 
     The stacker may have a transparent portion that serves as the visible indicator. 
     The medium-feeding section accommodates the stack of print medium that is at least partly curved. 
     The image-forming section is a tandem type electrophotographic apparatus with a plurality of image drum cartridges that are disposed in vertical alignment with one another. 
     Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limiting the present invention, and wherein: 
     FIG. 1 is a cross-sectional view of a printer according to a first embodiment of the invention; 
     FIG. 2 is a front view of the printer; 
     FIG. 3A is a perspective view of a guide plate; 
     FIG. 3B is an exploded perspective view of a paper-feeding section; 
     FIG. 3C is a cross-sectional top view of the paper-feeding section taken along lines III—III of FIG. 2; 
     FIG. 4 illustrates a relevant portion of a print engine when the print engine takes the form of a tandem type electrophotographic printer; 
     FIG. 5 is a cross-sectional view of a printer according to a second embodiment; and 
     FIGS. 6A-6C illustrate the flow of the print medium in the printer of FIG.  5 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention will be described in detail by way of example. 
     First Embodiment 
     FIG. 1 is a cross-sectional view of a printer according to a first embodiment of the invention. 
     FIG. 2 is a front view of the printer. 
     FIG. 3 is a cross-sectional view taken along lines III—III of FIG.  2 . 
     A printer according to the present invention will be described as being installed on the floor of an office. Referring to FIG. 1, a paper-feeding section  10 , an image-forming section  20 , and a transporting section  40  are disposed in vertical alignment with one another. The image-forming section is disposed over the paper-feeding section  10 . Above the image-forming section  20  are a stacker  30  and a transporting section  40  disposed side by side. The transporting section  40  transports a print medium such as paper from the image-forming section  20  to the stacker  30 . These sections  10 ,  20 ,  30 , and  40  are housed in a main body  1 . 
     The overall structure of the image-forming apparatus will be described. 
     A stack of print medium is accommodated in an upright position and each page of the print medium is fed in an upright position from the paper-feeding section  10 . The image-forming section  20  has a display  2  which displays the status of the image-forming section. The stacker  30  has a display  3  that displays whether the printed medium is present in or absent from the stacker  30 . The respective sections will be described in detail. 
     {Paper-feeding Section} 
     FIG. 1 illustrates the paper-feeding section  10  when it is opened. The paper-feeding section  10  is of a structure in which a stack of print medium is accommodated in an upright position. The paper-feeding section  10  includes a movable part and a stationary part. The movable part includes a print medium cassette  11  whose lower end is hingedly mounted to the main body so that when the cassette  11  is inclined outwardly the cassette  11  opens at an upward end thereof. The cassette  11  includes a guide plate  12 , a spring  13  that urges the guide plate  12  in a direction shown by arrow B against the main body  1 , a guide  14 , and a stopper  15  that guides the cassette  11  such that the cassette  11  is not disengaged from the main body. 
     The stationary part of the paper-feeding section  10  is fixed to the main body  1  and includes a guide  16 , a hopping roller  17 , a separator  18 , and a registry roller  19 . 
     The paper-feeding section  10  will be described in more detail with reference to FIGS.  1  and  3 A- 3 C. 
     FIG. 3A is a perspective view of a guide plate; 
     FIG. 3B is an exploded perspective view of a paper-feeding section; 
     FIG. 3C is a cross-sectional top view of the paper-feeding section taken along lines III—III of FIG. 2; 
     Referring to FIG. 3A, the guide  14  is in the shape of a part of a circular cone in which a cone has been partially cut away in a plane parallel to a center axis thereof. Thus, the guide  14  is convex whose diameter becomes smaller nearer a higher end portion of the guide  14 . The guide  14  is attached to the guide plate  12 . 
     Referring to FIG. 3B, the guide  16  is concave at a lower end portion thereof and is flat at a higher end portion thereof. The lower portion  41  of the print medium  4  is sandwiched by the guides  14  and  16  such that the print medium  4  is curved at its lower end portion. Therefore, the print medium  4  can withstand vertical stress exerted thereon and can be held in the upright position. Alternatively, the guide  14  may be provided on the main body  1  and the guide  16  on the guide plate  12 , while still holding the print medium in the upright position. Still alternatively, a spring  21  may be provided to urge the guide  16  in a direction shown by arrow C against the stack of print medium  4  so that when remaining number of pages of the print medium becomes small, the stack of print medium still maintains its curved position at its lower end portion. Thus, the print medium may be oriented substantially vertical regardless of the remaining number of pages of print medium. 
     As shown in FIGS. 3B and 3C, the guide  12  is urged by the spring  132  against the stack of the print medium  4  in the upright position such that the guide  12  urges the top end portion  42  toward the hopping roller  17 . The hopping roller  17  is in the shape of a cylinder, cut by a plane parallel to a longitudinal axis of the cylinder such that the hopping roller  17  has a D-shaped cross section. Therefore, the hopping roller  17  projects outwardly from the guide  16  toward the print medium  4  only when feeding the print medium  4  from the cassette  11 , thereby not imposing a frictional load on the print medium  4 . When the hopping roller  17  makes one complete rotation with the cassette  11  of FIG. 1 closed, the print medium  4  is fed out of the cassette  11  to the separator  8  and then to the registry roller  19 . The separator  18  separates the top page from multiple pages of the print medium  4  if the hopping roller  17  simultaneously feeds more than one page to the separator inadvertently. 
     There is provided a sensor, not shown, in front of the registry roller  19  in order to detect the print medium  4  when the print medium  4  arrives at the registry roller  19 . The registry roller  19  obstructs the print medium  4  eliminate the skew of the print medium  4 . The registry roller  19  then rotates slightly and then stops, thereby firmly holding the leading end portion of the print medium  4 . 
     {Image-forming Section} 
     The image-forming section  20  may take the form of an ink jet print engine, a plurality of electrophotographic print engines, or a plurality of thermal print engines. The display  2  of FIG. 2 indicates the operational status of the image-forming section. 
     When the image-forming section  20  of FIG. 1 is fully ready for a printing operation, the registry roller  19  feeds the print medium  4  in the upright position so that information is printed on the print medium  4  oriented in the upright position. 
     {Transporting section} 
     The transporting section  40  includes rollers  41  and carrier belts  42 . One of the rollers  41  is connected to a drive source such as a motor. After information has been printed on the print medium, the carrier belts  42  upwardly transport the print medium  4  sandwiched therebetween. The print medium  4  is then redirected by the redirecting section  43  and discharged to the stacker  30 . 
     {Stacker} 
     When the stacker  30  is opened, it takes up the dotted line position. The stacker  30  includes a stacker box  31 , a stack guide plate  32 , a sensor plate  33 , a switch  34 , a stopper  35 , and a handle  36 . The stopper  35  prevents the stacker box  31  from disengaging from the main body  1  when the top of the stacker box  31  is opened. The stack guide plate  32  is lightly urged by a torsion spring, not shown, outwardly from the apparatus, and yieldably guides the print medium  4 . The urging force is selected such that when the print medium enters between the stack guide plate  32  and the front side of the stacker box  31 , the print medium  4  is not suspended therebetween. The stack guide  32  holds the print medium  4  upright. The sensor plate  33  is disposed on the floor of the stacker box  31  and supports the print medium  4  in the stacker box  31 . The sensor plate  33  is urged upward by a torsion spring such that the weight of a single page of the print medium  4  causes the switch  34  to close. The switch  34  takes the form of a micro switch or a photo-sensor that detects the upward and downward movements of the sensor plate  33 . 
     {Operation} 
     When the image-forming section  20  receives a print instruction from a host apparatus such as a work station and a personal computer, not shown, the hopping roller operates to pick up the top page of the print medium  4  from the cassette  11 . The top page of the print medium  4  passes through the separator  17  and then through the registry roller  19  to the image-forming section  20  located above the paper-feeding section  10 . After the printing operation, the print medium  4  is transported further upwardly by the transporting section  40 , so that the print medium  4  is then redirected by the redirecting section  43  into the stacker box  31 . The inwardly projecting handle  36  serves to guide the print medium  4  to enter between the stack guide plate  32  so that the print medium  4  leans against the stack guide  32  with the printed surface facing the stack guide  32 . 
     The handle  36  guides the following page to enter between the preceding page and the handle  36  so that the pages of print medium are stacked in the order in which they are printed. 
     When pages of the print medium  4  are stacked in the stacker box  31 , the total weight of the pages pushes down the sensor plate  33 . Thus, the switch  34  shifts to its ON position so that the LED of the display  3  of FIG. 2 lights up to indicate the presence of the print medium  4 . 
     Upon completion of the printing operation, the user checks the LED on the display  3 . If the LED has lit up, the user draws the handle  36  in a direction shown by arrow A and takes out the printed medium  4  from the stacker  30 . 
     As mentioned above, the apparatus is relatively high but is of thin construction that occupies a smaller area on the floor of the office. 
     The present invention will be further described with respect to a case where the image-forming section  20  is a tandem type electrophotographic printer. 
     FIG. 4 illustrates a relevant portion of a print engine. 
     Referring to FIG. 4, a tandem type electrcophotographic printer incorporates four print engines stacked upwardly in order: a yellow image drum cartridge 60Y, a magenta image drum cartridge 60M, a cyan image drum cartridge 60C, and a black image drum cartridge 60K. 
     The yellow image drum cartridge 60Y includes the following mechanisms: a photoconductive drum 61Y; a charging device 62Y with, for example a charging roller; an exposing unit 63Y in the form of, for example, an LED head; and a developing unit 64Y with, for example, a developing roller and a toner chamber. 
     The other image drum cartridges are of the same construction as the yellow image drum cartridge 60Y and differ only in the color of toner. 
     A carrier belt  65  is disposed to oppose the image drum cartridges 60Y-60K. A belt charging roller  66  is located at the lower end of the carrier belt  65  and causes the carrier belt  65  to be charged so that the carrier belt  65  attracts the print medium  4  electrostatically thereto and transports the print medium  4  upward. 
     Transfer rollers 67Y, 67M, 67C, and 67K are disposed such that the carrier belt  65  is sandwiched between the transfer rollers and corresponding photoconductive drums 61Y, 61M, 61C, and 61K. 
     Just as in known electrophotographic printers, the charging device charges the surface of the photoconductive drum. The exposing unit illuminates the charged surface of the photoconductive drum to form an electrostatic latent image thereon. Then, the developing unit applies toner to the electrostatic latent image to develop the electrostatic latent image with the toner into a toner image. Then, the transfer roller transfers the toner image onto the print medium. 
     Each of auxiliary fixing units 68Y, 68M, and 68C are disposed directly over a corresponding one of the transfer rollers 67Y, 67M, and 67C. The auxiliary fixing units 68Y, 68M, and 38C weakly fix the respective toner images on the print medium  4  at a lower temperature than a final fixing operation so that the toner images just remain transferred on the print medium. There is provided a fixing roller  69  over the transfer roller 67K and fully fixes the toner images on the print medium  4 . 
     Since the toner images are weakly fixed by the respective auxiliary fixing units, the toner images will not come off the print medium  4  despite the fact that the print medium  4  is transported with the print medium  4  extending vertically. The auxiliary fixing operation requires only a low temperature, being advantageous in prolonging the life of the carrier belt as well as in saving overall power consumption. 
     As mentioned above, the present invention provides a board type image-forming apparatus of thin construction. 
     The image-forming apparatus according to the present invention occupies a small area on the floor of the office and can be used just like a part of a partition between departments in the office, allowing efficient utilization of office space. 
     Incorporating vertically stacked tandem type print engines is advantageous since the area occupied by the image-forming apparatus remains the same, while still allowing a highspeed color printing operation. 
     Second Embodiment 
     FIG. 5 is a cross-sectional view of a printer according to a second embodiment. 
     Referring to FIG. 5, the image-forming apparatus includes a paper-feeding section  10 , an image-forming section  20  disposed over the paper-feeding section  10 , a stacker  30  disposed over the image-forming section  20 , and a transporting section  40 . The paper-feeding section  10  and the image-forming section  20  are of the same construction as the first embodiment and the description thereof is omitted. 
     The stacker  30  according to the second embodiment has a transparent stacker box  31 . In addition to the transporting roller  41  and carrier belt  42 , the transporting section  40  is provided with a medium-orienting guide  44 , rear end shifting guide  45 , and fall guide  46 . 
     The aforementioned construction of the second embodiment allows the print medium to be stacked with the printed surface facing outside, so that the printed surface is visible from outside of the main body  1 . 
     {Operation and Construction of Transporting Section} 
     The operation and specific construction of the transporting section  40  will be described. 
     After printing, the medium-orienting guide  44  guides the print medium  4  so that the print medium  4  maintains its substantially vertical position and will not fall rightward of FIG.  5 . For this purpose, the medium-orienting guide  44  is disposed over the carrier belts  42  such that the leading end of the print medium  4  is oriented only in a limited range of direction. The rear end shifting guide  45  guides the leading end of the print medium  4  rightward. For this purpose, the rear end shifting guide  45  is near the top of the carrier belt  42  so as to cause the leading end portion of the print medium to flex rightward toward the medium-orienting guide  44 . The fall guide  46  guides the print medium  4  such that the leading end of the print medium  4  falls right downward. For smoothly guiding the print medium  4 , the fall guide  46  is disposed with its upper end in close contact with the top end of the carrier belts  42  and with its lower end extending right downward. 
     FIGS. 6A-6C illustrate the flow of the print medium. 
     The print medium  4  is guided by the aforementioned guides as follows: 
     When the leading end of the print medium  4  appears at the top end of the carrier belts as shown in FIG. 6A, the rear shifting guide  45  guides the leading end of the print medium  4  so that the print medium  4  advances along the medium-orienting guide  44 . When the print medium  4  is further advanced, the trailing end of the print medium  4  leaves the carrier belts  42  as shown in FIG. 6B, while at the same time the print medium  4  is pushed rightward by the rear end shifting guide  45 . As a result, the trailing end of the print medium  4  moves rightward and falls along the stack guide plate  32  as shown in FIG.  6 C. 
     The printed surface of the print medium  4  is not turned over as opposed to the first embodiment. The print medium  4  is received in the stacker box. The print medium  4  extends substantially vertically though somewhat declining against the stack guide plate  32  with the printed surface facing rightward of FIG.  5 . The pages of the print medium  4  are stacked one over the other. 
     Just as in the first embodiment, the sensor plate  33  and switch  34  cooperate to detect the stack of the print medium, so that when the print medium  4  is received in the stacker  30 , an LED or the like lights up to indicate the presence of the print medium  4  to the user. 
     In the second embodiment, the vertically extending print medium  4  in the stacker box  31  is visible through the transparent stacker box  31 . The visibility of the print medium  4  through the stacker box  31  eliminates the need of a visible indicator such as an LED to indicate the presence of the print medium in the stacker box  31 . 
     If the image-forming section  20  is implemented in the form of a thermal printer, the overall size of the printer can be even thinner, so that the printed medium  4  in the transparent stacker box  31  can directly serve as a “poster” or a “bulletin board”. When the printed medium  4  is posted, it does not require electric power as opposed to a CRT display or a plasma display that requires electric power. Thus, the image-forming apparatus according to the second embodiment can be used as an energy saving type display. 
     The recording apparatus according to the present invention has a paper-feeding section at a lower end of the apparatus and a paper stacker above the image-forming section. It is quite common that the paper cassette is usually supplied with a stack of 500 pages of print medium at a time. The stack of 500 pages is quite heavy and therefore it is desirable that the paper cassette is disposed at a relatively lower end of the apparatus in order to provide an easy-to-use apparatus. 
     Alternatively, the paper cassette may be disposed above the image-forming section and the paper stacker below the image-forming section. Then, the print medium is transported downwardly so that the print medium extends vertically due to its own weight. This may allow easy transportation of the print medium. Further, the downward transportation of the print medium allows feeding rollers to be used and eliminates the need for using carrier belts that were required to hold the print medium upright if the print medium was to be transported upwardly. Thus, the downward transportation of the print medium simplifies the construction of paper-transporting mechanism. 
     The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art intended to be included within the scope of the following claims.