Abstract:
An image forming apparatus includes an image forming unit including a developing device, a toner cartridge to store toner supplied to the developing device, a first memory which is provided in the toner cartridge and in which characteristic data of the toner is written, a detection mechanism to detect a parameter to influence toner cohesion, a second memory to store the detected parameter, and an arithmetic control mechanism to determine a use limit of the toner cartridge based on the characteristic data and the parameter.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is based upon and claims the benefit of priority from the prior U.S. Provisional Patent Application No. 61/359,448 filed on Jun. 29, 2010, the entire contents of which are incorporated herein by reference. 
     
    
     FIELD 
       [0002]    Embodiments described herein relate generally to an image forming apparatus and an image forming method. 
       BACKGROUND 
       [0003]    In an image forming apparatus, in general, in order to prevent defects such as toner cohesion due to heat from occurring, the temperature in a machine is controlled. However, the control of the temperature in the machine becomes difficult with the miniaturization of the apparatus. 
         [0004]    On the other hand, in recent years, fixing temperature is lowered by using a low melting point toner, and the power saving of the image forming apparatus is realized. In the low melting point toner, although a melting point is low, the storage property under a high temperature environment deteriorates. Thus, the image defect due to the cohesion occurs. 
         [0005]    Then, it is conceivable to suppress the cohesion by providing a cooling apparatus for lowering the temperature in the machine or by increasing the additive coating ratio of a toner particle. However, there occurs a problem that the cost increases. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  is a structural view of an image forming apparatus which is a four-tandem color printer of an embodiment; 
           [0007]      FIG. 2  is a schematic structural view of an image forming unit of the embodiment; 
           [0008]      FIG. 3  is a block diagram of components in which control of the image forming unit is performed of the embodiment; 
           [0009]      FIG. 4  is a correspondence table of address and information content in a memory of the image forming unit of the embodiment; 
           [0010]      FIG. 5  is a correspondence table of address and information content in a memory of a toner cartridge of the embodiment; and 
           [0011]      FIG. 6  is a flowchart of an operation of the embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0012]    Reference will now be made in detail to the present embodiment of the invention, an example of which is illustrated in the accompanying drawing. 
         [0013]      FIG. 1  is a structural view of an image forming apparatus which is a four-tandem color printer and is an example of an image forming apparatus (MFP) of an embodiment. As shown in  FIG. 1 , a secondary transfer roller  11  to transfer an image on an intermediate transfer belt  10  onto a transfer medium  12 , and image forming units  20 Y,  20 M,  20 C and  20 K of yellow, magenta, cyan and black are arranged along a conveyance direction (arrow direction) of the intermediate transfer belt  10 . 
         [0014]    The image forming units  20 Y,  20 M,  20 C and  20 K include photoreceptors  21 Y,  21 M,  21 C and  21 K as image carriers. Further, chargers  22 Y,  22 M,  22 C and  22 K as charging units, developing devices  23 Y,  23 M,  23 C and  23 K including developing rollers as developing members and containing developers including respective color toner particles of yellow, magenta, cyan and black and carrier particles, primary transfer rollers  24 Y,  24 M,  24 C and  24 K as transfer units, and cleaner units  25 Y,  25 M,  25 C and  25 K are provided around the respective photoreceptors. These are respectively arranged along rotation directions of the corresponding photoreceptors  21 Y,  21 M,  21 C and  21 K. 
         [0015]    The respective primary transfer rollers  24 Y,  24 M,  24 C and  24 K are disposed inside the intermediate transfer belt  10 , and nip the intermediate transfer belt  10  in cooperation with the corresponding photoreceptors  21 Y,  21 M,  21 C and  21 K. Exposure devices  26 Y,  26 M,  26 C and  26 K are respectively arranged so that exposure points are formed on outer peripheral surfaces of the photoreceptors  21 Y,  21 M,  21 C and  21 K between the chargers  22 Y,  22 M,  22 C and  22 K and the developing devices  23 Y,  23 M,  23 C and  23 K. The secondary transfer roller  11  is arranged outside the intermediate transfer belt  10  so as to contact therewith. 
         [0016]    A print operation is performed as described below by the image forming apparatus constructed as described above. A toner image of yellow formed on the photoreceptor of the image forming unit  20 Y is primarily transferred onto the intermediate transfer belt  10 . The toner image is formed in the image forming unit  20 Y. The same process is performed also in the image forming units  20 M,  20 C and  20 K in synchronization with a timing of the toner image formation in the image forming unit  20 Y. The toner images of magenta, cyan and black formed on the photoreceptors of the image forming units  20 M,  20 C and  20 K are also sequentially primarily transferred onto the intermediate transfer belt  10 . 
         [0017]    The transfer medium  12  is conveyed from a cassette (not shown), and is sent to the intermediate transfer belt  10  by an aligning roller (not shown) in synchronization with the timing of the toner image on the intermediate transfer belt  10 . 
         [0018]    A bias (+) having a polarity opposite to a toner charge polarity is applied to the secondary transfer roller  11  by a power source (not shown). As a result, the toner image on the intermediate transfer belt  10  is transferred onto the transfer medium  12  by a secondary transfer voltage applied between the intermediate transfer belt  10  and the secondary transfer roller  11 . A fixing unit (not shown) to fix the toner transferred on the transfer medium  12  is disposed, and a fixed image is obtained by causing the transfer medium  12  to pass through the fixing unit (not shown). 
         [0019]    Incidentally, here, although the description is made on the example in which the image forming units are arranged in the order of yellow, magenta, cyan and black, the color order is not particularly limited. 
         [0020]    Hereinafter, the details of the image forming apparatus of the embodiment will be described. 
         [0021]      FIG. 2  is a schematic structural view of an image forming unit  20  of the image forming apparatus which is constructed as described above and in which an image is formed. Incidentally, the image forming units  20 Y,  20 M,  20 C and  20 K have the same structure. 
         [0022]    As shown in  FIG. 2 , a charger  22 , a developing device and a cleaning unit  25  are arranged around a photoreceptor  21 . A toner cartridge  27  is mounted to the developing device  23 . Further, a timer  28  to detect a time when the toner cartridge  27  is attached, and a thermometer  29  to detect a temperature in a machine are provided. 
         [0023]    The image forming unit includes a memory  30  in which toner information and control information are stored, and the toner cartridge  27  includes a memory  31  in which toner characteristic information is stored. 
         [0024]    In the image forming unit  20  as described above, a print operation is performed as described below, and a use limit of the toner cartridge  27  is obtained.  FIG. 3  is a block diagram of components in which control is performed. As shown in  FIG. 3 , a CPU  32  as an arithmetic control mechanism for controlling the image forming unit  20  is connected to the timer  28  and the thermometer  29  which are detection mechanisms to detect parameters to influence toner cohesion, and a display part  33  to display instructions to a user. 
         [0025]    The CPU  32  is connected to the memory  30  of the image forming unit  20  and is connected to the memory  31  of the toner cartridge  27  through a transmission and reception part  34 . 
         [0026]      FIG. 4  is a correspondence table of address and information content in the memory  30  of the image forming unit, and  FIG. 5  is a correspondence table of address and information content in the memory  31  of the toner cartridge. 
         [0027]    As shown in the table of  FIG. 4 , the memory  30  includes, for respective addresses, an area (A 001 ) in which an identification code is stored, an area (A 002 ) in which a reference toner characteristic value (for example, Tg (glass transition point)=55° C.) is stored, and an area (A 003 ) in which toner characteristic data such as Tg read from the memory  31 , described later, is written. 
         [0028]    Further, in order to detect a print time and a temperature which are the parameters to influence the toner cohesion, the memory  30  includes an area (A 004 ) in which a printing start date and time is written, an area (A 005 ) in which a printing end date and time is written, and an area (A 006 ) in which the temperature is written, and further includes an area (A 007 ) in which a temperature integrated value at the last printing described later is written, which is an integrated value for determining the use limit, and an area (A 008 ) in which a threshold (for example,  5500 ) of the temperature integrated value is stored. 
         [0029]    As shown in the table of  FIG. 5 , the memory  31  includes, for respective addresses, an area (B 001 ) in which an identification code is inputted, and an area (B 002 ) in which toner characteristic data such as Tg (glass transition point) of toner stored in the toner cartridge  27  is written. The toner characteristic data may be any characteristic that influences the toner cohesion, and may be another temperature characteristic, storage property or the like. 
         [0030]    The storage property is evaluated by, for example, an easiness of toner cohesion obtained by a following measurement method. 
       &lt;Storage Property Measurement Method&gt; 
       [0031]    (1) After toner of 20 g is put in a polyethylene bottle of 100 cc, the bottle is covered with a lid, and is heated for 8 hours in a water tank of 50° C. 
         [0032]    (2) The toner is extracted from the water tank and is left for 8 hours at a room temperature. 
         [0033]    (3) The toner after heating is put on a sieve of 42 mesh, and is sieved while a vibration is applied by a powder tester made by HOSOKAWA MICRON CORPORATION. 
         [0034]    (4) An amount of toner on the sieve is measured. 
         [0035]    As the measured amount of toner becomes large, the cohesion easily occurs. 
         [0036]    Further, the memory  31  includes an area (B 003 ) in which the date and time written in A 004  is written, and an area (B 004 ) in which the temperature integrated value at the last printing is written. 
         [0037]      FIG. 6  is a flowchart. As shown in  FIG. 6 , a power source is turned ON or a front cover is opened, and a new toner cartridge is attached (Act  1 ). 
         [0038]    The identification code is stored in A 001  of the memory  30 , the reference toner characteristic value is stored in A 002 , and the threshold of the temperature integrated value is stored in A 008 . It is determined whether the identification code inputted in A 001  is coincident with the identification code inputted in  3001  of the memory  31  (Act  2 ). When not coincident, the toner cartridge is replaced, or printing is executed in a print or copy mode of an inconsistent case (Act  13 ). 
         [0039]    When the identification codes are coincident with each other, the present date and time detected by the timer  28  is written in A 004  (Act  3 ), and the presence or absence of writing of data in  3003  is determined (Act  4 ). When writing is not performed, the date and time of A 004  is written in B 003  (Act  5 ). Incidentally, when the data is written in  3003 , the temperature integrated value at the last printing, described later, is written in  3004 . 
         [0040]    The toner characteristic data Tg of  3002  and the temperature integrated value of B 004  are read, and are written in A 003  and A 007  (Act  6 ) respectively. A print ready state occurs, and printing is performed (Act  7 ). 
         [0041]    The present date and time detected by the timer  28  at the time of completion of the printing is written in A 005 , the temperature detected by the thermometer  29  at the time of completion of the printing or during the printing is written in A 006  (Act  8 ), and a temperature integrated value (D) is obtained by a following expression (Act  9 ). 
         [0000]      temperature integrated value ( D )=toner load coefficient ( A )×temperature in machine ( B )×print time ( C )
 
         [0000]      toner load coefficient ( A )=reference toner characteristic value ( A 002)/toner characteristic data ( A 003) 
         [0000]      temperature in machine ( B ): temperature exceeding 50° C.=temperature in machine ( A 006)−50
 
         [0000]      print time ( C )=printing completion date and time ( A 005)−printing start date and time ( A 004)
 
         [0042]    The obtained temperature integrated value (D) is written in A 007 . When the temperature integrated value at the last printing is written in A 007 , the temperature integrated value at the last printing is added, and the obtained value is newly written in A 007  (Act  10 ). The temperature integrated value written in A 007  is newly written in B 004 . 
         [0043]    It is determined whether the temperature integrated value (D) written in A 007  exceeds the threshold of A 008 , for example,  5500  (Act  11 ). When exceeds the threshold, it is determined that the toner cartridge reaches the use limit. The display part  33  displays instructions to the user, for example, replacing the toner cartridge, removing and shaking the toner cartridge (manually agitating the toner), or stopping a two-sided mode in which the temperature more rises (Act  12 ). Further, when the image forming apparatus is connected to a network, a service department may be informed that the cartridge reaches the use limit. 
         [0044]    Incidentally, when the temperature integrated value reaches the threshold or a specified value less than that, a process condition such as a charge voltage, a developing bias and a laser output power, an agitation condition in the toner cartridge  27  or the like may be changed. 
         [0045]    The print operation is performed as described above, the use limit of the toner cartridge is obtained, and the replacement instruction of the toner cartridge or the like is performed to the user, so that the image defect due to the toner cohesion can be prevented. 
         [0046]    While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omission, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.