Abstract:
A device for the electrophotographic production of image patterns has at least one printing unit to which toner is supplied and has an arrangement for transferring used toner from a cleaning station of the printing unit to a used toner container. The arrangement for transferring can be interrupted to enable changing the used toner container without interrupting the printing operation of the device.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application is a National Stage filed under 35 USC 371 of PCT/DE97/02385, filed Oct. 15, 1997, which claimed priority from German Application 196 42 570.0 filed Oct. 15, 1996. 
   BACKGROUND OF THE INVENTION 
   The invention is directed to a device for the electrographic generation of image patterns on a recording medium, particularly printer or copier, having at least one printing unit to which toner is supplied from a toner reservoir. According to various aspects of the invention, the invention is directed to means for delivering the toner and/or for eliminating the toner in such a device. 
   When the toner&#39;s supply in the toner reservoir in a known printer is running out, a signal is generated that causes the printer to be arrested or stopped. An operator must then refill toner from a standardized refilling container into the toner reservoir. After the end of the filling procedure, printing operations can be re-assumed. A similar case applies for handling used toner that is collected from 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 with an alarm signal. 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 felt particularly given high-performance printers that should print or, respectively, copy optimally interruption-free in order to achieve their full efficiency. 
   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. 
   DE-A-39 21 806 discloses a dry copier device wherein the excess toner is collected in a collecting container that is arranged outside the copier device. The collecting container is connected to the copier device with a conveyor conduit. The conveyor conduit contains a downpipe, so that the toner is further-conveyed due to the influence of gravity. The elimination of the toner in the direction of the collecting container ensues with the assistance of a worm conveyor. 
   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 shut off by this safety device. An opening that is not connected to the safety device is incorporated into the device cover. 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. 5,309,211 describes a laser printer. The used toner output by a cleaning station is conveyed to a used toner container with the assistance of an intermittently operating worm conveyor. 
   SUMMARY OF THE INVENTION 
   An object of the invention is to specify a device for the electrographic generation of image patterns on a recording medium wherein the apparatus operation is as continuous as possible. In particular, it is an object of the invention to enable the continuous elimination of used toner without interruption of apparatus operations. 
   This object is achieved by an improvement in an apparatus for electrographically producng 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 and has means for elimination of used toner collected at the cleaning station by transferring the used toner to a used toner container. The improvement is that the means is interruptible to allow replacing or changing of the used toner container without interrupting the printing operation and the means has a controllable coupling that can be actuated between a drive and conveyor shaft for the transfer of the toner from the cleaning station. 
   According to an exemplary embodiment of the invention, an opening is provided in a device cover through which the toner reservoir can be refilled from the outside without interrupting operations. In particular, a closeable opening through which the toner reservoir can be refilled is provided in the apparatus store in the region of a filling opening of the toner reservoir. For safety reasons, the device door can be connected to an electrical safety means that interrupts operation of the device when the device door is opened. In order to be nonetheless able to refill toner, an opening can be inserted in this device door whose condition, i.e. whether open or closed, is not evaluated for the operation of the printer. The toner reservoir can then be filled through this closeable opening. An opening of the device door with the result that the security means shuts the device off is not required. 
   As a result of the invention, an electrophotographic device can work interruption-free with high efficiency, even when the toner consumption is extremely high. 
   Exemplary embodiments of the invention are explained below with reference to the drawing. In this explanation, further features of various aspects of the invention, advantageous effects and the combination of inventive features are described. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a front view of a high-performance printer with closed flaps; 
       FIG. 2  is the front view of  FIG. 1  with open flaps; 
       FIG. 3  is a schematic view when refilling the toner reservoir; 
       FIG. 4  is the 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 with the refilling bottle inserted; 
       FIG. 6  is a schematic view with the upper flap of  FIG. 5  in the closed condition; 
       FIG. 7  is a schematic view of a toner reservoir with mouthpiece and a cap removed from the mouthpiece of the toner reservoir. 
       FIG. 8  is a side view of the toner reservoir; 
       FIG. 9  is a view of the toner reservoir from the front; 
       FIG. 10  is a schematic view of an arrangement for the generation of an under-pressure in the toner reservoir; 
       FIG. 11  is the connection of a connecting hose, shown schematically; 
       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 introduced into a drawer; 
       FIG. 19  is a diagram for defining various operating conditions; 
       FIG. 20A  is a schematic view of the drawer with a full, used toner container in an opened position to illustrate the condition Z 1 ; 
       FIG. 20B  is a schematic view of the drawer with the used toner container removed to illustrate the condition Z 2 ; 
       FIG. 21A  is a schematic view of the drawer with a partially filled, used toner container in the opened condition to illustrate the condition Z 3 ; 
       FIG. 21B  is a schematic view of the drawer in a closed position and the container no yet full to illustrate the condition Z 4 ; and 
       FIG. 22  is a schematic side view of further exemplary embodiments for 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 from which toner is supplied to the respective printing unit is allocated. The toner reservoir essentially permanently installed in the high-performance printer  10  and must be refilled at time intervals via a filling opening  20  depended on the use. The two device 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 the toner reservoir. The device doors  12   a ,  12   b  are connected to an electrical security means that interrupts operations of the high-performance printer  10  when either of the doors  12   a  and  12   b  are in an open condition. In order to avoid such an interruption and nonetheless enable a refilling with toner, a respective opening closeable by flaps  14 ,  16  is provided in the region of the respective filling opening  20  of the two toner reservoirs, said openings not being connected to the safety system. A control panel  18  that, as 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 device door  12   a ,  12   b  and interrupting the printing operations. In the closed condition of the flap  14 ,  16 , the internal parts of the high-performance printer  10  are again completely protected from the outside world. 
     FIG. 3  shows the condition when refilling with a standardized toner refilling bottle  24 . The refilling bottle  24  is introduced into an opening of the toner reservoir  22  through an opening  28  in the cladding panels  30  with its bottleneck  26  in an oblique position and the toner reservoir  22  is filled 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 is potentially spilled during filling. The access to the toner reservoir  22  for the refilling bottle  24  is fashioned such that a spilling of toner when the refilling bottle  24  is applied can be easily avoided, and the emptying of the refilling bottle  24  can ensue unproblemmatically by the force of gravity as a result of its oblique attitude. 
   It can be seen in the upper part of the Figure that the operating panel  18  can be pivoted. A filling opening of the toner reservoir  22  is fashioned such that, when filling with the standardized refilling bottle  24 , this can be introduced with play at the swivelled-out operating 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 reading of the cladding of the high-performance printer  10 . According to  FIG. 6 , it can be seen that the cuboid-shaped housing form is again completed in the closed condition of the flap  14 . 
     FIG. 7  shows the toner reservoir  22  as a partial excerpt. The toner reservoir  22  holds the contents of two refilling bottles each having respectively 0.6 kg of toner. Accordingly, the toner reservoir  22  has a receptacle volume of approximately 3.6 liters, whereby the tone arising during the filling procedure is to be taken into consideration as an additionally required space when designing the toner reservoir  22 . 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 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 applied in an oblique attitude and a spilling of toner is avoided. The center axis of the opening of the mouthpiece  34  approximately intersects 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 tightly closed with a closure cover  37  after the refilling. The closure cover  37  has a spring snap  38  at its underside with which, after being introduced, it engages into the mouthpiece  34  with a snap-in event. The closure cover  37  has a handle  40  at its upper side. 
     FIG. 8  schematically shows the structure of the toner reservoir  22  from the side. The center axis  44  of the mouthpiece  34  intersects the center axis  46  of the toner reservoir at approximately half height. A channel  50  via which toner  54  is conveyed off in the direction of the arrow  48  to the printing unit 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  is assured. A filling level sensor  58  emits 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 printing having to ensue. Two pivot arms  52  that turn oppositely toward one another see to it that toner adhering to the inside wall of the toner reservoir  22  is scraped off and a dense cone  42  arises. 
     FIGS. 10 ,  11  and  12  are directed to a further aspect of the invention in accord wherewith a slight vacuum or under-pressure is generated in the toner reservoir.  FIG. 10  illustrates the refilling of the toner reservoir  22 . When refilling toner from the refilling bottle  24 , toner dust  62  arises that can emerge from the annular gap opening at the mouthpiece  34  without further measures. Inventively, air is extracted from the toner reservoir  22  via an air elimination opening  66  with a ventilator or fan  64 , at least during the filling procedure, as a result whereof air is suctioned through the annular gap at the bottleneck in the direction of the arrows  68 . Toner dust  62  cannot emerge. The air elimination opening  66 , according to  FIG. 10 , is provided with a filter  70  at the inside of the toner reservoir  22  that retains toner. The air elimination 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 connector  71  is connected to a connecting hose  72  that leads into the inside  74  of the printer. The ventilator  64  in this version is arranged in the inside  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 inside  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 in the toner reservoir  22  is built up no later than the beginning of the toner refilling event, this having to be retained until the end of the refilling event. 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 decrease in 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 into the characteristic. This alarm signal means that the toner will soon run out and toner must be refilled. Within the remaining time wherein there is still adequate toner in order to maintain printing operations, an operator must replenish the toner. The position of the printing level sensor  58  can be modified, as a result whereof the range of remaining time within which the refilling can ensue without interrupting printing operations illustrated by an arrow  76  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 printing operations are shut off. In addition to generating an abort signal after a predetermined time has elapsed, it can also be generated dependent on the use of the remaining toner. For example, the use of toner can be determined on the basis of a toner mark regulation in conjunction with a clock toner conveying. Given this toner mark regulation, a control pulse for toner conveying is output for a dosing shaft controlled step-by-step given every toner mark on the photoconductor drum of the printing unit that is inked too lightly. The time for a toner delivery, i.e. for a specific amount of toner, can be set in defined fashion per control pulse. When the remaining amount of toner will be 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 in order to maintain operations free of printing operations can be optimally determined. 
   Another possibility of determining the toner use and generating the abort signal is by determining the use of toner on the basis of the printed picture elements and of the printing contrast that has been set. Of course, it is also possible to determine 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 can be extremely short for the refilling, since the toner consumption is highly dependent on the degree of blackening of the printed pages. 
   On the basis of the current consumption of toner and the amount of refilled toner after the occurrence of the alarm signal, it is also possible to continuously determine the actual filling level in the toner reservoir  22 . This actual filling level can then be displayed on a display at the printer. 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. 14–22  are directed to means for eliminating used toner that is collected by the cleaning system in the printing unit.  FIG. 14  schematically shows the elimination of the used toner output from the cleaning station  80  via an adapter unit  82  into a used toner container  84 . When the bulk 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 piece, which assures that the toner does not adhere to it or collect at it either due to its coercive forces or due to the residual electrical charge, which can lead to a blockage. 
   The structure of the adapter unit  82  is shown in  FIGS. 15A ,  15 B and  15 C in a side view, a plan view and in a side cross-section. The adapter unit  82  has a stable collar  88  at the side of the cleaning unit  20  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 movements and deformations without a permanent deformation remaining. The hose  92  expands in the fashion of a conical frustum in the direction toward the used toner container. 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 independent of one another. In  FIG. 16A , the principal; descending channel  94  wherein the used toner overcomes a descending path of approximately 100 mm is entered with dash-double dot lines, and the toner descends without a clumping of the used toner or an adhesion thereof to the inside ensuing. 
   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 the used toner container (not shown in  FIG. 17 ) is being replaced. 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 inside surface separating from the neck  108  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 condition 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 drawer  110  with the force F by a pivot 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 pivot element  118  is pivotably seated around a pivot bearing  119 . A microswitch  122  acquires the position of the drawer  110 . Its signal is evaluated for monitoring, as explained in greater detail below. 
   In the illustrated, retracted condition of the drawer  110 , the locking plate  100  engages into a stop edge  124  of a side panel of the drawer  110 . For replacing the used toner container  84 , as mentioned, the locking plate  100  is raised and pivoted out perpendicular to the paper plane, so that the adapter unit  82  detaches from the used toner container  84 . A ramp  126  serves the purpose of assuring that the adapter unit  82  remains in a compressed condition in the withdrawn condition of the drawer  110 . In this hinged-up position, the hose  92  is bent off once or repeatedly and thereby seals the adapter unit in view of 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 microswitch  122 . The locking plate  100  thereby again lowers, the bend or, respectively, bends in the hose  92  released and used toner can again emerge from the adapter unit  82  into the used toner container  84 . A further microswitch  200  detects the raised or, respectively, lower position of the locking plate. 
   For monitoring the various operating conditions during replacement of the used toner container free of printing operations, the microswitch  122 , the filling level sensor  120  and the microswitch  200  are employed for signaling. The various operating conditions Z 1  through Z 4  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 microswitch  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 microswitch  200  is employed for checking the respectively proper position of the locking plate  100 , for example whether the locking plate has been 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 certain amount of toner has arisen, then it must be assured that this can be eliminated from the adapter unit  82  into the used toner container. 
   The statuses Z 1  through Z 4  are defined according to the aforementioned signal statuses F and M. These various operating statuses Z 1  through Z 4  are graphically illustrated in  FIGS. 20A ,  20 B,  21 A and  21 B In the condition Z 1  ( FIG. 20A ), the drawer  110  is withdrawn and the used toner level  130  is high, i.e. the used toner container is to be replaced. In this operating 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 interpreted, for example by determining the plurality of printed picture elements and of the contrast that is thereby set or by determining the amount of conveyed toner. 
   In the status Z 2 , the pivot element  118  swivelled against the filling level sensor  120  simulates a full used toner container. The drawer  110  is closed and the microswitch  122  is actuated. When no used toner container is introduced within a predetermined time given this operating condition, then printer operations are suspended. 
   In the operating status Z 3  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 given this operating condition, then printer operations are suspended. 
   The operating status Z 4  defines the printing mode 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 printing operations and monitor the replacement of the used toner container free of printing operations 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 at a status when there is still adequate space for toner and there is still adequate time remaining in order to undertake steps for the replacement of the used toner container  84 . When the remaining time until the full condition of the used toner container  84  is exceeded, then the control must immediately arrest printer operations in order to prevent an overfilling of the used toner container  84  and a possible toner jam. The remaining time can be determined on the basis of printed pages or the time can be fixed dependent on the occurrence of used toner. The occurrence of used toner derives from the transfer printing efficiency and can be exactly determined by the control, for example, on the basis of the printed picture elements in conjunction with the transfer printing efficiency and the printing contrast. 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 printer operation, the used toner that arises must be collected in the interim.  FIG. 22  shows various measures as alternative or combined possibilities. The used toner conveyed by a conveyor  132  proceeds into the used toner container  84  via an adapter hose  136  in the normal operating condition. The conveyor  132  is driven by a drive  134 . When a controllable coupling is inserted between this drive  134  and the conveyor  132 , the conveyor  132  can be at a standstill during the replacement of the used toner container  84 . The used toner arising 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 , this closure  138  being actuated for replacing the used toner container. Further, an intermediate container  142  can be provided that replaces the used toner container  84  while the used toner container  84  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 microswitch  122  that determines the withdrawal of the drawer  110 . Dependent on the signal of the microswitch  122 , the corresponding actuators can then be activated.