Abstract:
In order to replace out-of-date flowing medium in a system, where the medium comprises a component which ages, out-of-date flowing medium is removed and a quantity of fresh flowing medium or a fresh component are added while maintaining a given level of the flowing medium.

Description:
RELATED APPLICATION  
       [0001]     The present continuation application is related to application Ser. No. 10/468,237 “DEVICE AND METHOD FOR THE REPLACEMENT OF EXPIRED DEVELOPER”, filed Feb. 2, 2004, Bernhard Schlageter and Uwe Höllig, inventors. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     The invention concerns a device and a method to replace at least one component of a pourable medium. Furthermore, the invention concerns the use of such a device in a printer or copier.  
         [0003]     Examples of systems in which pourable medium are used are electro-photographic or ionographic printers or copiers. The pourable medium used therein is a developer, especially a two-component developer that contains a toner and a magnetic carrier respectively in particle form.  
         [0004]     In printers or copiers operating according to the electro-photographic principle, charge images of characters (such as texts or drawings) to be printed are generated on an intermediate carrier, for example a drum with an electro-photographic layer. The intermediate carrier with the charge images is directed into a development station in which the charge images are developed and thereby made visible. Upon the development, the toner particles of a two-component developer are conveyed in the direction of the intermediate carrier and are electrically attracted onto the intermediate carrier by the charge carrier. The carrier particles are conveyed back to the development station. The developed charge images are transferred and fixed upon a recording medium, for example a paper web. The toner material within the two-component developer is used in the development valve. Fresh toner material is refilled corresponding to this use. The carrier material conveyed back is subject to an aging process, whereby the print quality or copy quality can suffer. Therefore, it is also necessary to renew the carrier material little by little.  
         [0005]     A printer device or copier device is specified in WO 98/39691 (of which reference is made here to its entire disclosure) in which a recording medium can be printed upon in monochrome and/or color. A plurality of developer stations are thereby provided for which, respectively, one color is associated for one colored print. In order to maintain the print quality in printers of such a type, a replacement must occur at specific time intervals due to the expiration of the developer or the expired components contained therein in the form of the carrier. For example, this could hitherto occur such that development stations are completely emptied and subsequently filled, which is very time-consuming and is associated with an interruption of the operation of the printer or copier.  
         [0006]     Replacement of the developer with expired carrier with fresh developer can also occur such that developer stations are supplied with fresh toner and fresh carrier separate from one another, such that a definite amount of the toner and carrier ensuring the print quality or copy quality is always present in the developer, such that the printer operation or copier operation must not be interrupted.  
         [0007]     A device for the replacement of expired developer with fresh developer in a development station of an electro-photographic device is known from U.S. Pat. No. 4,358,196. This known device comprises two metering devices, via one of which fresh developer is supplied to the developer station, and via the other of which expired developer is removed from the development station, such that a developer ensuring good print quality is always present in the development station.  
         [0008]     Given replacement of the developer with expired carrier, it is important that a specific volume of developer with a defined toner concentration and carrier concentration (meaning a defined proportion of toner to carrier) is always present in a development station. Over the entire lifespan of a printing device, a total fill quantity of developer guaranteeing proper functioning must always be present. The toner concentration can be regulated in its own regulation cycle, such that an amount of toner ensuring the print quality is always present in the development station. The regulation can occur such that the toner concentration is detected and regulated either directly by means of a sensor, or indirectly via detection of the inking of the printing. However, given direct regulation, the toner concentration cannot be precisely determined due to inevitable control deviations, and given indirect regulation, the toner concentration can in part not be determined at all, whereby losses in quality can arise.  
         [0009]     Typically, the ratio of toner to carrier for the volume of the supplied two-component developer is known. However, the ratio of toner to carrier in the volume of the removed developer can vary from the ratio in the supplied developer, because the toner concentration in the development station can vary higher or lower than the toner concentration of the supplied developer due to the control deviations. However, because both volumes are equal, the proportion of the carrier in the removed developer can vary higher or lower than the proportion of the carrier in the supplied developer.  
         [0010]     If the replacement of the developer is implemented uniformly and constantly, as is the case in the device according to the US patent specification cited above, the carrier quantity in the developer station can drift ever further higher or lower, given a large number of alternating cycles. This means that the development station can overflow or run empty in the extreme case, whereby the printer or copier is incapable of functioning.  
         [0011]     A device and a method for the replacement of at least one component of a pourable medium is known from EP 0 043 505 A2. The pourable medium with the expired component is removed from a container, and a quantity of fresh pourable medium is supplied into the container. Two metering devices are provided, from the first of which the developer station is constantly supplied fresh developer, and from the other of which used developer is constantly removed from the developer station in an equal quantity.  
         [0012]     A developer station is known from U.S. Pat. No. 5,450,178, in which a mix of toner and carrier particles is present in an upper chamber according to the exemplary embodiment according to  FIG. 4 . The proportion of toner is higher than is necessary for the typical usage. The mix from the upper chamber is transferred little by little into a container, whereby an expired mixture in this container is dispensed into a lower chamber, dependent on the signal of a sensor that analyzes the contents in the container. In this manner, the total quantity of the mixture can be maintained at a constant value.  
         [0013]     A developer unit is known from U.S. 5,095,338, in which a mixture of toner particles and carrier particles is present in a chamber (compare in particular  FIG. 2 ). A quantity of carrier particles and toner particles is supplied from the container to the development material in the chamber. The ratio of toner particles to carrier particles in the container is greater than in the chamber, such that expired developer material is continually renewed. A sensor system observes the composition of the development material in the chamber and initiates via a controller the supply of fresh developer material.  
         [0014]     A copier with at least two developer stations for at least two different colors is known from EP 0 043 505 A2, in which a fresh developer component is supplied from a common reservoir container to these developer stations at the respective supply intake. This developer is a liquid developer.  
         [0015]     Reference is made to the documents JP 59 100 471 A, JP 2000 122 424 A, and WO 01/06325 A as further relevant prior art.  
       SUMMARY  
       [0016]     An object of the invention is to specify a device and a method in which the expired component in a container is continually renewed, and the properties of the pourable medium remain largely the same.  
         [0017]     In a method or device for replacement of at least one expired component of a pourable medium, a container is provided having a removal output at one side for at least the one expired component of the pourable medium, and providing at an opposite side of the container a supply input in which a quantity of at least one of fresh pourable medium and a fresh component is supplied. The removal output comprises a nose whose tip defines a predetermined developer fill level in the container, the nose being part of an overflow designed as a trap so that when the fill level rises over the predetermined developer fill level defined by the nose, expired developer is removed over the overflow so that the fill level in the container regulates itself dependent on the predetermined developer fill level and the supply input quantity. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]      FIG. 1  is a first exemplary embodiment of a device;  
         [0019]      FIGS. 2A through 2C  are an exemplary embodiment to determine a predetermined quantity of a pourable medium for the supply to the device according to  FIG. 1 ;  
         [0020]      FIG. 3  is a second exemplary embodiment of a device;  
         [0021]      FIG. 4  is a third exemplary embodiment of a device;  
         [0022]      FIG. 5  is a fourth exemplary embodiment of a device;  
         [0023]      FIG. 6  is a schematic representation of a complete system of a developer station of an electro-photographic printer or copier with a device; and  
         [0024]      FIG. 7  is a schematic representation of a plurality of developer stations of an electro-photographic printer or copier with a single device to supply fresh pourable medium to these stations. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0025]     For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the preferred embodiment illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated device, and/or method, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur now or in the future to one skilled in the art to which the invention relates.  
         [0026]     A fresh pourable medium or, alternatively, only the fresh component is continuously supplied to the container. Inside the container, the fill level of the medium is maintained at a constant value, whereby compensation evolves are observed. In this manner, the expired component in the medium is replaced little by little, such that the properties of the medium (which is a mixture) remain largely the same. What is particularly advantageous is that a developer is used as a pourable medium to develop a latent image. Such a developer can be fluid or formed of particles. In particular, two-component developers can be used that, in addition to a toner material, also contain a carrier material made from magnetic particles. The expired carrier can be supplied alone as fresh material to the container; alternatively, fresh developer that also contains toner material in addition to the expired carrier can also be supplied.  
         [0027]     According to a further aspect, a printer or copier is specified that comprises a plurality of developer stations for a plurality of different colors. Each developer station comprises a device according to the type of the device further mentioned above, within which the expired component of the pourable medium is exchanged little by little. Each developer station receives fresh expired component, in particular carrier material in a two-component developer, from a reservoir container common to all developer stations. Furthermore, each developer station has a separate toner reservoir container from which toner of the respective color is supplied to the container of the respective developer station. In this manner, it is possible to collectively supply with carrier material a plurality of developer stations with differently colored toner material, such that the expired carrier material in each developer station is exchanged little by little. It is also not necessary to undertake a separate exchange of carrier material or developer for each developer station.  
         [0028]     The invention is subsequently more closely explained using exemplary embodiments according to the figures of the drawings. Thereby shown are:  
         [0029]      FIG. 1  shows a first exemplary embodiment in a development station  50  of an electro-photographic device, for example an electro-photographic printer or copier, shown excerpted. The device comprises a container  10  for a composite two-component developer  11  made from toner particles and carrier particles. The container  10  comprises a paddle wheel  9  with scoops or paddles  18  that rotate in the direction of an arrow A. The developer  11  forms a developer sump  12  in the lower part of the container  10 .  
         [0030]     A supply input  13  is provided on one side of the container  10 , via which fresh developer that contains the toner and carrier in a predetermined ratio or, alternatively, only fresh carrier  14  is supplied in the direction of an arrow B. In the latter case, toner from a toner container is supplied via an additional feed (not shown). On the side of the container  10  opposite the supply input  13 , a removal output  15  is provided via which expired developer  16  that contains the expired carrier and toner is removed in the direction of an arrow C. The expired developer  16  is directed via an overflow device  17  in the connection region of the removal output  15  of the container  10 . This overflow  17  is designed in the form of a trap standing on its head and contains a nose  17 ′ whose tip defines a predetermined developer fill level  17 ″.  
         [0031]     If a predetermined quantity of fresh developer or fresh carrier  14  is supplied to the container  10  via the supply input  13 , the fill level rises over the predetermined developer fill level  17 ″ and, because the removal output  15  is in the range of the predetermined developer fill level  17 ″, the same amount of expired developer  16  is removed via the overflow  17 . The fill level in the container  10  therefore regulates itself dependent on the predetermined developer fill level  17 ″ and the supply quantity. The event continues until the predetermined developer fill level  17 ″ is once again reached.  
         [0032]     The supply input  13  and the removal output  15  are preferably arranged in the container  10  such that supplied fresh developer or fresh carrier  14  can not drain off together with the expired developer  16  during the replacement event. This is the case in the exemplary embodiment according to  FIG. 1 , when the input and output  13  or  15  arranged on opposite sides of the container  10 .  
         [0033]     The  FIGS. 2A  to  2 C show an exemplary embodiment for the measurement of a predetermined quantity of fresh developer or carrier  14 . Two synchronized valves  21  and  22  are provided one behind the other or, respectively, one under the other in a tube  20  leading to the supply input  13  according to  FIG. 1  in which fresh developer or fresh carrier  14  is fed in from above.  
         [0034]     In a first phase according to  FIG. 2A , the valve  21  is open and the valve  22  is closed, such that fresh developer or fresh carrier  14  is directed in the direction of an arrow D via the tube  20  to the closed valve  22 . The opening time of the valve  21  defines a determined quantity of fresh developer or fresh carrier  14 .  
         [0035]     In a second phase according to  FIG. 2B , both valves  21  and  22  are closed, whereby the predetermined quantity of developer or carrier to be supplied to the mixer  10  according to  FIG. 1  is measured, i.e. this quantity is contained between the two valves  21  and  22 .  
         [0036]     In a third phase according to  FIG. 2C , the valve  21  is closed and the valve  22  is opened, such that the quantity of developer or carrier located between the two valves  21  and  22  drains off in the direction of an arrow E to the developer supply input  13  according to  FIG. 1 .  
         [0037]      FIG. 3 , in which identical elements as in  FIG. 1  are provided with identical reference numbers, shows a second exemplary embodiment in which, in contrast to the exemplary embodiment according to  FIG. 1 , the supply of fresh developer or fresh carrier  14  is regulated via the removal or expired developer  16 . As in the exemplary embodiment according to  FIG. 1 , this exemplary embodiment is also a self-regulating device due to a predetermined developer fill level in the container  10 . A synchronized valve  30  is provided in the removal output  15  whose opening time fixes the quantity of removed expired developer  16 . If the developer fill level sinks by a certain amount, the same amount of fresh developer or carrier  14  is supplied via the supply input  13 .  
         [0038]     The developer supply input  13  in the exemplary embodiment according to  FIG. 3  must terminate at the least with the desired developer fill level. The exact vertical position is thereby furthermore directed according to the pressure created by the mixture in the developer sump  12  at the predetermined developer fill level in order to block the inflow of fresh developer or carrier  14  via the developer mixture itself. Due to the removal of expired developer  16 , the total amount of developer in the developer sump  12  decreases and therewith leads to a lowered developer level and simultaneously to a lower pressure at the output of the supply input  13 . Due to this lower pressure at the supply input  13 , fresh developer or carrier  14  can be supplied. This process continues until the predetermined developer fill level is reached again or the counter-pressure at the output of the supply input  13  blocks the supply of fresh developer or carrier  14 .  
         [0039]     In summary, the position of the supply input  13  is established dependent on the pressure of the medium prevailing at the output of the supply input  13 .  
         [0040]     The determination of a predetermined quantity of developer or carrier, in addition to the setting via the valve  30 , can alternatively also occur via suction extraction or a feed screw in the lower part of the developer sump  12 , which is, however, not shown in  FIG. 3 .  
         [0041]     The predetermined fill level is defined by a fill level sensor  45  in the exemplary embodiments according to  FIGS. 4 and 5 , whose elements that are the same as in the previous figures are provided with the same reference numbers.  
         [0042]     In the exemplary embodiment according to  FIG. 4 , the valve  30  synchronized in the removal output  15 , whose opening time sets the quantity of the removed expired developer (compare this to  FIG. 3 ), is controlled by a control module  44 .  
         [0043]     Via the fill level sensor  45 , it is determined whether the developer in the container  10  has reached the predetermined fill level or not. A decision is made with regards to this according to a control block S 1 , whether or not the condition of the fill level “full” is reached. If this is not the case (i.e. the decision “no” is made), a valve control module  44 ′ is activated that controls, for its part, a valve  30 ′ by which fresh developer or fresh carrier  14  is supplied to the supply input  13  via a supply tube  20 . This occurs until the fill level sensor  45  determines that the predetermined fill level is reached.  
         [0044]     If the fill level “full” is reached (i.e., the decision “yes” is made in the control block), the valve control module  44 ′ is no longer activated (i.e. fresh developer or carrier  14  is no longer supplied).  
         [0045]     In the exemplary embodiment according to  FIG. 5 , a determined quantity or a determined volume of fresh developer or carrier  14  is supplied via a device corresponding to the  FIGS. 2A  to  2 C with two valves  21  and  22 . For the function of the two valves  21  and  22 , refer to the embodiments according to the  FIGS. 2A  to  2 C. It is determined by the fill level sensor  45  whether or not the developer in the container  10  has exceeded the predetermined fill level. A decision is thereby made by the control block S 2  whether or not the condition of the fill level “full” is reached. If this is the case (i.e. a decision “yes” is made), the valve control module  44  is activated that controls, for its part, the valve  30 , by which the removal output  15  of expired developer  16  is supplied. This occurs until the fill level sensor  45  determines that the predetermined fill level is once again reached.  
         [0046]     If the fill level “full” is clearly fallen short of (i.e. the decision “no” is made in the control block S 2 ), the valve control module  44  is no longer activated (i.e. expired developer  16  is no longer removed).  
         [0047]      FIG. 6  shows an exemplary embodiment of a completely implemented development station, in which two separate control loops for toner supply or carrier supply to the mixture container  10  are provided. The toner concentration TK in the container  10  is detected by a toner concentration sensor  32 , by which a decision is made as to whether or not the toner concentration TK is lower than a desired value. This toner concentration TK is typically defined as a percent value of the weight of toner within the developer. Typical TK values are 2 to 10%. A TK value of 6% means that 6 g of toner are contained in 100 g of developer. The toner supply occurs from the toner reservoir container  35  containing a toner  36 , to which a toner conveying drum is provided which is driven by a driving motor  38 .  
         [0048]     If it is established that the toner concentration TK is lower than the desired value S (i.e. the decision “yes” is made in the control block S 3 ), a control module  43  for the driving motor is activated that, for its part, operates the toner conveying drum  37  in terms of the supply of toner to the container  10 .  
         [0049]     An intermediate carrier  34 , which can be a drum with an electro-photographic layer, is inked by an inking drum  33  by means of a two-component developer that is comprised, as mentioned, from toner and carrier.  
         [0050]     A driving motor  31  for the paddlewheel  9  is controlled with a time meter by a control module  41 . A change interval T is set by the time meter  42 , in which fresh developer or fresh carrier  14  is respectively supplied. As was already specified using the exemplary embodiments according to  FIGS. 1 and 5  in connection with the exemplary embodiment according to the  FIGS. 2A  to  2 C, given a decision by the control block S 4  that the change interval T is elapsed (i.e. upon the query t=T, the decision is “yes”), the valves  21  and  22  are activated by the valve control module  44  in terms of the supply of fresh developer or carrier  14  to the mixer  10  via the supply input  13 . Upon a decision “no” (i.e. the change interval T is not yet elapsed), the valve control module  44  is not activated, and therefore no fresh developer or carrier  14  is supplied.  
         [0051]      FIG. 7  shows an exemplary embodiment with a plurality of developer stations  50 ,  51 ,  52  for a printing with, respectively, various colors. In this exemplary embodiment, it is provided that exclusively fresh carrier  14  is collectively supplied from the common reservoir container  39  to the development stations  50  to  52 . As specified using the exemplary embodiments according to FIGS.  1  to  5 , expired developer is removed respectively via a removal output  15  and a common duct  56 , whereby this removal can occur via a cyclone filter  53  attached to a fan  54 . The filtered developer  55  contains different-colored toner and can no longer be used.  
         [0052]     An important advantage of the exemplary embodiment according to  FIG. 7  can be seen in that, on the one hand, a continuous exchange of a pourable medium (namely, the two-component developer) is possible without interruption of the operation of the printing system, as well as without drastic sudden changes of the properties of the pourable medium and, on the other hand, the perpetuation of a predetermined fill level over the total life of the system is possible without knowledge of the concentration of the components in the pourable medium.  
         [0053]     The exemplary embodiments explained previously are suited not only for electro-photographic devices of the type explained above, but rather in practice for all devices that operate with expired pourable used substances. For example, it can thereby also be a fluid development system with a carrier fluid as an expired medium, or also systems that are independent of image development systems and operate with expired pourable mediums to be exchanged.  
         [0054]     While a preferred embodiment has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiment has been shown and described and that all changes and modifications that come within the spirit of the invention both now or in the future are desired to be protected.