Abstract:
An apparatus for electrophotographic production of images on a printing medium, such as a printer or copier, has a printing unit fed with toner from a toner storage tank. Toner can be refilled into the tank through a closable opening without interrupting the printing operation.

Description:
BACKGROUND OF THE INVENTION 
     The invention is directed to an apparatus for the electrophotographic production of image patterns on a recording medium, particularly or printer or copier, comprising at least one printing unit to which toner is supplied from a toner reservoir. According to various inventive aspects, the invention is directed to devices for delivering the toner and/or for eliminating the toner in such an apparatus. 
     When the toner supply in the toner reservoir has just about run out, a signal is produced in a known printer that causes the printer to be arrested or stopped. An operator must then replenish toner from a standardized refilling container into the toner reservoir. After the end of the filling procedure, printing operations can be reassumed. The similar case is true for handling used toner that is collected by a cleaning station in the printer or copier. When a used toner container has reached a high filling level, an operator is informed of this by an alarm signal. The printing operations are interrupted and the full used toner container is replaced with an empty one. The described procedure reduces the availability, economic feasibility and user-friendliness of the printer or, respectively, copier. This is particularly felt given high-performance printers that should print or, respectively, copy optimally free of interruptions in order to achieve their full efficiency. 
     U.S. Pat. NO. 4,967,234 discloses a copier device whose device covers, for example device doors, are connected to an electrical safety means. When the device doors are opened, the copier device is turned off by this safety means. An opening that is not connected to the safety means is incorporated into the device covering. A toner container with fresh toner can be supplied to the copier device via this opening. The fresh toner is refilled into a container. The toner container emptied in this way is then filled with used toner. 
     U.S. Pat. No. 5,329,340 discloses an apparatus for the electrophotographic generation of image patterns on a recording medium. The apparatus contains two toner reservoirs. When the first toner reservoir is empty, a switch is made to the second toner reservoir. The used toner that arises is collected in a used toner container. When the used toner container is not available, the used toner is collected in an additionally provided container inside the apparatus or outside the apparatus. 
     WO-A-95 10074 discloses a color printer with a developing unit. Toner from a toner reservoir is supplied to this developing unit with a delivery conduit and a pump. 
     SUMMARY OF THE INVENTION 
     An object of the invention is to specify an apparatus for the electrographic production of image patterns on a recording medium, whereby the apparatus operation is possibly optimally continuous. In particular, it is an object of the invention to enable a toner delivery without interrupting the apparatus operations. 
     This object is achieved by an improvement in an apparatus for electrographically producing image patterns on a recording medium, such as a printer or copier, which apparatus comprises at least one printing unit to which toner is supplied from a toner reservoir that is essentially permanently installed within the apparatus and can be refilled at chronological intervals via a filling opening, an apparatus cover for covering internal parts of the apparatus as well as the toner reservoir, an electrical safety means that interrupts operation of the apparatus when the apparatus cover is opened, and an opening provided in the apparatus cover through which the toner reservoir can be refilled from the outside without interrupting the printing process. The improved apparatus has means for generating or creating a slight under-pressure or vacuum in the toner reservoir at least during a reflecting procedure. 
     Exemplary embodiments of the invention are explained below with reference to the drawing. Further features of various inventive aspects, advantageous effects and the combination of features of the invention are referred to in this explanation. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front view of a high-performance printer with closed flaps; 
     FIG. 2 is a front view of FIG. 1 with opened flaps. 
     FIG. 3 is a schematic view when refilling the toner reservoir; 
     FIG. 4 is a view of FIG. 3 with closed flaps; 
     FIG. 5 is a schematic view with a flap in the proximity of the upper edge of the printer in the condition wherein the refilling bottle is introduced; 
     FIG. 6 is a schematic view with the upper flap of FIG. 5 in its closed condition; 
     FIG. 7 is a schematic view of the toner reservoir with a cap removed from a mouthpiece; 
     FIG. 8 is a side view of the toner reservoir; 
     FIG. 9 is a view of the toner reservoir from the front; 
     FIG. 10 for the generation of an under-pressure in the toner reservoir; 
     FIG. 11 is a schematic view of the connection of a connecting hose; 
     FIG. 12 is a schematic view of the arrangement of a filter outside the toner reservoir; 
     FIG. 13 is a diagram of the decrease of the amount of toner over the operating time; 
     FIG. 14 is a schematic side view of the adapter unit connected to a used toner container; 
     FIGS. 15A,  15 B and  15 C are different vies of an adapter unit with FIG. 15A being a side view, FIG. 15B being a top plan view and FIG. 15C being a cross-sectional view; 
     FIG. 16A is a side view of the adapter in a relaxed state; 
     FIG. 16B is a side view of the adapter in a compressed state; 
     FIG. 17 is a side view of the adapter unit when replacing the used toner container; 
     FIG. 18 is a side view of the used toner container inserted into a drawer; 
     FIG. 19 is a diagram directed to the definition of various operating container; and 
     FIG. 20A is a schematic view of the drawer with a full, used toner container in an opened position to illustrate the condition Z1; 
     FIG. 20B is a schematic view of the drawer with the used toner container removed to illustrate the condition Z2; 
     FIG. 21A is a schematic view of the drawer with a partially filled, used toner container in the opened condition to illustrate the condition Z3; 
     FIG. 21B is a schematic view of the drawer in a closed position and the container no yet full to illustrate the condition Z4; and; 
     FIG. 22 further exemplary embodiments of a replacement of the used toner container without interrupting printing operations. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 schematically shows the front side of a high-performance printer  10  that can print single sheets at high speed. The high-performance printer  10  contains two printing units (not shown) to each of which a respective toner reservoir is allocated, and toner is supplied to the respective printing units from each of these reservoirs. The toner reservoirs are essentially permanently installed in the high-performance printer  10  and must be refilled via a filling opening  20  at chronological intervals dependent on the use. The two apparatus doors  12   a ,  12   b  pivotable toward the outside serve the purpose of covering internal parts of the high-performance printer  10  as well as of the toner reservoir. The device doors  12   a ,  12   b  are connected to an electrical security means that interrupts the operation of the high-performance printer and  12   b  are in an open condition. In order to avoid such an interruption and nonetheless enable a refilling with toner, an opening  20  respectively closeable by flaps  14 ,  16  that are not connected to the security system is provided in the region of each of the two toner reservoirs. A control panel  18  that, as shall be described later, can be pivoted out is arranged above the flap  16 . 
     FIG. 2 shows the front view of the high-performance printer  10  of FIG. 1 with opened flaps  14 ,  16 . In the opened condition of the flaps, the filling openings  20  of the toner reservoirs  22  become visible. Toner from a standardized refilling bottle can thus be refilled into the toner reservoirs  22  without opening the apparatus door  12   a ,  12   b  and interrupting the printing operations. In the closed condition of the flaps  14 ,  16 , the internal parts of the high-performance printer  10  are again completely protected against the outside world. 
     FIG. 3 shows the condition when refilling with a standardized toner refilling bottle  24 . The refilling bottle  24  has its bottle neck  26  introduced in an oblique attitude through an opening  28  in the metal paneling  30  and into an opening of the toner reservoir  22  to fill this reservoir with toner. After the filling, the flap  16  closes the opening  28 . 
     The flap  16  is shaped such that it defines an upwardly opened container space  32 . This container space  32  serves the purpose of collecting toner that may potentially be spilled during filling. The access to the toner reservoir  22  for the refilling bottle  24  is fashioned such that a spilling of toner when placing the refilling bottle  24  can be easily avoided and the emptying of the refilling bottle  24  can ensue unproblemmatically on the basis of gravity due to its oblique attitude. 
     It can be seen in the upper part of the FIG. that the control panel  18  can be pivoted. The filling opening of the toner reservoir  22  is fashioned so that, when refilling with the standardized refilling bottle  24 , this can be introduced with play at the swivelled-out control panel  18 . 
     To facilitate an understanding, FIG. 4 shows the flap  16  in the closed condition wherein the opening  28  is completely covered. 
     FIG. 5 shows another exemplary embodiment wherein the flap  14  is arranged in the upper edge region of the paneling of the high-performance printer  10 . According to FIG. 6, it can be seen that the cuboid-shaped housing form is again completed with the closed condition of the flap  14 . 
     The toner reservoir  22  is shown as a partial excerpt in FIG.  7 . The toner reservoir  22  holds the contents of two refilling bottles each respectively having 0.6 kg of toner. Accordingly, the toner reservoir  22  has a receptacle volume of approximately 3.6 liters, whereby the cone arising during the filling procedure is to be taken into consideration in the design of the toner reservoir  22  as an additionally required space. A mouthpiece  34  that is fixed by a spring element  35  is introduced into the toner reservoir  22 . The mouthpiece  34  has a funnel-shaped section  36  that assures that an optimally small annular gap arises between the opening of the mouthpiece  34  and the refilling bottle. The center axis of the opening of the mouthpiece  34  proceeds obliquely relative to the vertical, so that the refilling bottle can be attached in an oblique attitude and spilling of toner is avoided. The center axis of the opening of the mouthpiece  34  intersects, roughly, the center axis of the toner reservoir  22 , this assuring that the cone is built up in the middle of the toner reservoir  22 . The opening of the mouthpiece  34  is closed tight with a closure cover  37  after the refilling. The closure cover  37  has a spring snap  38  at its underside with which it engages into the mouthpiece  34  with a snap-in event after being introduced. The closure cover  37  has a handle  40  at its upper side. 
     FIG. 8 schematically shows the structure of the toner reservoir  22  viewed from the side. The center axis  44  of the mouthpiece  34  intersects the center axis  46  of the toner reservoir at roughly mid-height. A channel  50  via which toner  54  is conveyed off to the printing unit in the direction of the arrow  48  is located in the lower region of the toner reservoir. 
     FIG. 9 shows a view from the front. The mouthpiece  34  is located in the middle of the toner reservoir  22 , as a result whereof a uniform delivery and an optimum, uniform emptying of the toner reservoir  22  being assured. A filling level sensor  58  outputs an alarm signal when the toner  54  has reached the level  60  (hatched line). The remaining amount  56  is then still adequate in order to enable a refilling of the toner without an interruption of the printing having to ensue. Two pivot arms  52  that rotate oppositely relative to one another see to it that toner adhering to the inside wall of the toner reservoir  22  is scraped off and a dense bulk cone  42  arises. 
     FIGS. 10,  11  and  12  are directed to a further aspect of the invention according to which a slight or vacuum is generated in the toner reservoir. FIG. 10 illustrates the refilling of the toner reservoir  22 . Toner dust  62  that can also emerge from the annular gap opening at the mouthpiece  34  without further measures arises when refilling toner from the refilling bottle  24 . Inventively, air is extracted from the toner reservoir  22  via an air discharge opening  66  by a ventilator or fan  64  at least during the filling process, as a result whereof air is suctioned through the annular gap at the bottle neck in the direction of the arrows  68 . Toner dust  62  cannot emerge. The air outlet opening  66  is provided according to FIG. 10 with a filter  70  at the inside of the toner reservoir  22  and, this filter  70  retains toner. The air outlet opening  66  is arranged in the upper region of the toner reservoir  22 , preferably in the toner-free area. 
     FIG. 11 shows an alternative embodiment. A discharge nozzle  71  is connected to a connecting hoses  72  that leads into the inside  74  of the printer. In this version, the ventilator  64  is arranged in the interior  74  of the printer. FIG. 12 shows a development of the arrangement according to FIG.  11 . In this development, the filter  70  is arranged in the interior  74  of the printer and not in the toner reservoir  22 . 
     During operation of the printer, a control sees to it that the under-pressure is built up in the toner reservoir  22  no later than at the beginning of the toner refilling procedure; this under-pressure must be maintained until the end of the refilling procedure. For example, the start of the extraction can ensue with an electromechanical switch that is actuated when the toner reservoir  22  is opened. It is also possible to maintain the under-pressure in the toner reservoir  22  during the entire operation of the printer. 
     FIG. 13 shows a diagram with reference whereto the drop of the toner filling level in the toner reservoir  22  over the operating time of the printer is illustrated. The operating time is shown on the abscissa; the toner filling level is shown on the ordinate. The toner filling level  75  at which the filling level sensor  58  outputs an alarm signal is entered in the characteristic. This alarm signal means that the toner will soon run out and toner must be refilled. An operator must refill toner within the remaining time wherein adequate toner is still present in order to maintain printer operations. The position of the filling level sensor  58  can be modified, as a result whereof the range of remaining time shown by an arrow  76  within which the refilling can ensue without interrupting printing can be set. The alarm signal is preferably output when the filling level lies at 10-40% of the overall amount of toner in the toner reservoir  22 . When the remaining toner is used, then the control must generate an abort signal with which the printer operation is shut off. In addition to producing an abort signal after the lapse of a predetermined time, it can also be generated dependent on the consumption of the remaining toner. For example, the use of toner can be identified on the basis of a toner mark control in combination with a clocked toner replenishment. Given this toner marked control, a control pulse for a toner replenishment is output for a dosing shaft controlled step-by-step at every toner mark on the photoconductor drum of the printing unit that is inked too lightly. The time for a toner replenishment, i.e. for a specific toner amount, can be set in defined fashioned per control pulse. When the remaining amount of toner is used after the occurrence of the alarm signal can be identified from the addition of the conveying times and the dosing quantity per time unit. The abort signal can be accordingly generated. In this way, the overall time within which a refilling of toner must ensue can be optimally defined in order to maintain operations free of printing interruptions. 
     Another possibility of identifying the toner consumption and generating the abort signal is by determining the use of toner based on the printed picture elements and the printing contrast that has been set. Of course, it is also possible to define a specific number of pages that are still allowed to be printed after the occurrence of the alarm signal until the abort signal is generated. What is thereby disadvantageous is that the remaining time for the refilling can be extremely short since the toner consumption is highly dependent on the degree to which the printed pages are blackened. 
     It is also possible to continuously identify the actual filling level in the toner reservoir  22  on the basis of the current consumption of toner and the amount of replenished toner after the occurrence of the alarm signal. This actual filling level can then be displayed at the printer on a display. The level at which the filling level sensor  58  outputs its alarm signal then serves as measuring point for the actual toner filling level in the toner reservoir  22 . 
     The following FIGS. 14 through 22 refer to devices for discharging used toner that is collected by the cleaning system in the printing unit. FIG. 14 schematically shows the elimination of the used toner output by the cleaning station  80  via an adapter unit  82  into a used toner container  84 . When the fill level  86  in the used toner container  84  has reached a specific height, the used toner container  84  must be replaced with an empty one. In order to enable this in a simple way, the used toner container  84  is not connected directly to the cleaning station  80 ; rather, the adapter unit  82  is provided as a connecting member, which assures that the toner does not adhere to it or collect either due to its cohesion forces or due to the residual electrical charge, which can potentially lead to a blockage. 
     FIGS. 15A,  15 B and  15 C show the structure of the adapter unit  82  in a side view, a plan view and in a lateral cross-section. At the side of the cleaning unit  20 , the adapter unit  82  has a stable collar  88  that is fashioned as a rotary part. A further rotary part  90  that, as shall be explained later, is accepted in a locking plate is provided at the side of the used toner container  84 . A flexible hose  92  is arranged between the collar  88  and the rotary part  90 . This hose  92  is composed of silicone-containing plastic and is vulcanized into the parts  88 ,  90 . Due to the flexibility of the hose  92 , a horizontal compensation of design tolerances can ensue on the one hand; on the other hand, this hose  92  can execute vertical motions and deformation without retaining a deformation. The hose  92  expands in the direction toward the used toner container in the fashion of an explainding conical frustum. As a result thereof, a permanent collection of used toner in the hose  92  is avoided. 
     FIG. 16B illustrates the flexibility of the adapter unit  82 , whereby it can execute an angular motion of approximately 8° at both ends independently of one another. The principal descending channel  94  in which the used toner overcomes a drop distance of approximately 100 mm without a clumping of the used toner or an adhesion to the inside ensuing is entered with dash-double dot lines in FIG.  16 A. 
     Returning to FIG. 14, it can be seen that the adapter unit  82  is connected to a swivel arm  96  of the cleaning unit  80  by a clamped connection  98 . The rotary part  90  is accepted in a recess of a locking plate  100  that is seated in a peg  102  to rotate in a plane  104  that resides perpendicular to the paper plane. The locking plate  100  is pre-stressed in the direction of the used toner container  84  with a tension spring  106 . 
     FIG. 17 shows the adapter unit  82  and the locking plate  100  when replacing the used toner container (not shown in FIG.  17 ). For unlocking, the locking plate  100  is pressed up upon exertion of a force F of approximately 15 N, whereby the rotary part  90  has its inner surface releasing from the neck  108  (FIG. 14) of the used toner container  84  while compressing the hose  92 . In this condition, the used toner container  84  can be moved out, as explained in greater detail in the following FIG.  18 . 
     FIG. 18 shows a side view of the used toner container  84  introduced into a drawer  110 . The operating status wherein used toner is conducted into the used toner container  84  is shown. The drawer  110  is seated on telescoping rails  112  and can be pushed out in the direction of the arrow  114  in order to replace the used toner container  84 . The used toner container  84  is pressed against the back wall  115  of the door  110  with the force F by a swivel element  118  formed of sheet metal and is thus pressed against the acquisition surface of a capacitative filling level sensor  120 . The force F is derived from a tension spring  116 . The swivel element  118  is pivotably seated around a pivot bearing  119 . A micro-switch  122  acquires the position of the drawer  110 . Its signal is evaluated for monitoring, as shall be explained in greater detail later. 
     In the illustrated, introduced condition of the drawer  110 , the locking plate  100  engages into a stop edge  124  of a lateral panel of the drawer  110 . For changing the used toner container  84 , the locking plate  100 , as mentioned, is raised and pivoted out perpendicular to the paper plane, so tat the adapter unit  82  separates from the used toner container  84 . A ramp  126  serves the purpose that the adapter unit  82  remains in a compressed condition in the withdrawn condition of the drawer  110 . The hose  92  is bent off once or repeatedly in this hinged-up position and thereby seals the adapter unit with respect to the used toner. Toner particles cannot escape from the adapter unit in this condition; after the drawer has been withdrawn by about 300 mm, the full used toner container  84  can be replaced with an empty one. The new used toner container is pressed against the filling level sensor  120  by the swivel element  118 , so that a stable operating position is achieved. Subsequently, the drawer  110  is again closed, this being signaled by the micro-switch  122 . The locking plate  100  thereby lowers, the bend or, respectively, bends in the hose  92  are undone and used toner can again emerge from the adapter unit  82  into the used toner container  84 . A further micro-switch  200  detects the raised or, respectively lowered position of the locking plate. 
     The micro-switch  122 , the filling level sensor  120  and the micro-switch  200  are employed for signaling and for monitoring the various operating conditions when replacing the used toner container free of printing interruptions. The various operating conditions Z1through Z4 are shown in FIG. 19 dependent on the signals of the two detectors  120  and  122 . The filling level sensor  120  has a signal status F=0 when the used toner container  84  has a high filling level. It has the value F=1 when the filling level is low. The micro-switch  122  has the value M=0 when the drawer  110  is pulled out; it has the value M=1 when the drawer is completely pushed in. The signal of the micro-switch  200  is employed to check the respectively proper position of the locking plate  100 , for example whether the locking plate is lowered, after the drawer was pushed back in. A determination can be made with this information as to whether a toner transport from the adapter unit  82  through the hose  92  is possible. When a specific quantity of toner has arisen, then it must be assured that this can be disposed of from the adapter unit  82  into the used toner container. 
     The statuses Z1 through Z4 are defined according to the aforementioned signal statuses F and M. These various operating conditions Z1 through Z4 are graphically shown in FIGS. 20A,  20 B,  21 A and  21 B. In condition Z1 (FIG. 20A, left), the drawer  110  is withdrawn and the used toner level  130  is high, i.e. the used toner container should be replaced. In this operation condition, the used toner container  84  must be replaced within a predetermined changing time; otherwise, the control generates an abort signal and printing operations are suspended. Instead of the changing time, the amount of used toner that has actually arisen can also be evaluated, for example by determining the plurality of printed picture elements and the contrast thereby set or by determining the amount of conveyed toner. 
     In the condition Z2, the swivel element  118  pivoted against the filling level sensor  120  simulates a full used toner container. The drawer  110  is closed and the micro-switch  122  is actuated. When no used toner container is introduced within a predetermined given this operating condition, then printing operations are suspended. 
     In the operating condition Z3 according to FIG. 21A, the drawer  110  is opened and the filling level sensor  120  indicates that the used toner level  130  still lies below the full level. When the drawer is not closed within a predetermined time in this operating condition, then printing operations are suspended. 
     The operating condition Z4 defines the printer operation without malfunction. The drawer  110  is closed and the capacitative filling level sensor  120  indicates that the used toner level  130  is low and the used toner container  84  can still accept an adequate quantity of used toner. 
     By evaluating the signal statuses F and M of the sensors  120  and  122 , the control of the printer can reliably control the printer operation and monitor the replacement of the used toner container free of printing interruptions in all operating conditions. 
     FIG. 22 shows further possibilities for the replacement of the used toner container without having to interrupt printing operations. What is critical for the replacement of the used toner container free of printing operations is that the filling level sensor  120  outputs a full signal in a condition when adequate space is still present for toner and there is still enough time in order to undertake steps for the replacement of the used toner container  84 . When the time remaining until the full condition of the used toner container  84  is exceeded, then the control must immediately arrest printing operations in order to prevent an over-filling of the used toner container  84  and a possible toner jam. The remaining time can be identified on the basis of printed pages or the time can be defined dependent on the occurrence of used toner. The used toner occurrence derives from the transfer printing efficiency and can be exactly determined, for example, on the basis of the printed picture elements in combination with the transfer printing efficiency and the printing contrast, being identified by the control. In this version, the time until the replacement of the used toner container has been completed is maximum. 
     In order to be able to undertake the replacement of the used toner container during ongoing printing operations, the used toner that occurs must be collected in the interim. Various measures are shown in FIG. 22 as alternative or combined possibilities. The used toner conveyed by a conveyor  132  proceeds via an adapter hose  136  into the used toner container  84  in the normal operating condition. The conveyor  132  is driven by a drive  134 . When a control of a coupling is inserted between this drive  134  and the conveyor  132 , then the conveyor  132  can be at a standstill during the replacement of the used toner container  84 . The used toner occurring during the replacement then remains in the conveying channel of the conveyor  132 . 
     Another possibility is comprised in arranging a closure  138  at the level of the flexible adapter hose  136  that is actuated for replacing the used toner container. An intermediate container  142  can also be provided that takes place of the used toner container  84  when it is being replaced and collects the used toner. The operation of the controllable coupling, of the intermediate container  142  or of the closure  138  can be controlled via the micro-switch  122  that identifies when the drawer  110  has been withdrawn. Dependent on the signal of the micro-switch  122 , the corresponding actuator elements can be activated.