Patent Document

CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based upon and claims the benefit of priority from the prior U.S. Provisional Application No. 61/355,813 filed on Jun. 17, 2010, the entire contents of which are incorporated herein by reference. 
    
    
     FIELD 
     Embodiments described herein relate generally to an image forming apparatus and an image forming method. 
     BACKGROUND 
     In an image forming apparatus, a memory storing data such as characteristics of each toner cartridge is provided for the toner cartridge, and control of transfer, fixing or the like is performed based on the data. 
     In the image forming apparatus as stated above, when a power source is turned on, or a new toner cartridge is mounted to the image forming apparatus, it is determined that there is a possibility that the toner cartridge is replaced. All data is read from a memory on a toner cartridge side, and is read into a memory on an image forming apparatus side. For example, at the time of return from a sleep mode for energy saving, or at an opening and closing of a toner cartridge, reading of all data is similarly performed. 
     At this time, respective components of the image forming apparatus are also started, and the data is read before completion of start-up of, for example, a fixing unit including a heat source which takes a relatively long time to start. 
     In a color printer of an image forming apparatus, since data is sequentially read from memories of respective toner cartridges of yellow, magenta, cyan and black, a readout time is four times longer than that of a monochrome printer. Although it is conceivable to reduce data content in order to shorten the data readout time, the reduction of the data content itself is difficult. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a structural view of an image forming apparatus as a four-tandem color printer of an embodiment; 
         FIG. 2  is a schematic structural view of an image forming unit of the embodiment; 
         FIG. 3  is a block diagram of a structural portion in which readout is performed from a memory on a toner cartridge side of the embodiment; 
         FIG. 4  is a correspondence table of address and information content in a memory on an image forming apparatus side of the embodiment; 
         FIG. 5  is a correspondence table of address and information content in the memory on the toner cartridge side of the embodiment; and 
         FIG. 6  is a flowchart of data readout of the embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to the present embodiment of the invention, an example of which is illustrated in the accompanying drawing. 
       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 the 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 . 
     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. 
     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. 
     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 . A 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. 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 . 
     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 . 
     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. 
     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. 
       FIG. 2  is a schematic structural view of an image forming unit  20  of the image forming apparatus of the embodiment. Incidentally, the image forming units  20 Y,  20 M,  20 C and  20 K of the respective colors have the same structure. 
     As shown in  FIG. 2 , a charger  22 , a developing device  23  and a cleaner unit  25  are arranged around a photoreceptor  21 . A toner cartridge  27  is mounted to the developing device  23 . A memory  28  is provided to the image forming apparatus and a memory  29  in which control data is written is attached to the toner cartridge  27 . 
     Incidentally, the toner cartridge  27  may be integrated with the developing device and the like to form a developing unit. In this case, the memory  29  has only to be attached to the developing unit. Besides, the memory  29  is separated from the toner cartridge  27  or the like and may be separately mounted to the image forming unit. 
     In the image forming apparatus as stated above, readout is performed from the memory on the toner cartridge as described below, and the image forming apparatus is placed into a print operation ready state. 
       FIG. 3  is block diagram of a structural portion in which the readout of data from the memory on a toner cartridge side is performed. As shown in  FIG. 3 , a CPU  31  as a processing mechanism of arithmetic control or the like is connected to the respective components of the image forming units  20 Y,  20 M,  20 C and  20 K such as the chargers  22 Y,  22 M,  22 C and  22 K, the memory  28  on the image forming apparatus side, a temperature and humidity sensor  30  as a measuring equipment, and a display part  32  to display an error or the like, and is connected to memories  29 K,  29 Y,  29 M and  29 C of toner cartridges  27 K,  27 Y,  27 M and  27 C. 
       FIG. 4  shows a correspondence table of address and information content in the memory  28  of the image forming apparatus, and  FIG. 5  shows correspondence tables of address and information content in the memories  29 K,  29 Y,  29 M and  29 C of the toner cartridges. 
     As shown in the table of  FIG. 4 , the memory  28  of the image forming apparatus includes, for each address, an area (A001) in which an identification code for identifying a machine type is inputted, areas (A002-A005) in which color codes of the image forming units  20 K,  20 Y,  20 M and  20 C are inputted, a measurement data area (A006) in which temperature and humidity data from the temperature and humidity sensor  30  is written, areas (A007-A010) in which toner control data from the memories  29 K,  29 Y,  29 M and  29 C, described later, are written, and areas (A011-A014) in which standard control data of the respective toners are inputted. 
     As shown in the table of  FIG. 5 , each of the memories  29 Y,  29 M,  29 C and  29 K of the toner cartridge includes areas in which an identification code (00h), a color code (01h), a data reference destination (02h), a correction coefficient (03h) as a correction value for standard control data, and control data (04h-FFh) corresponding to temperature and humidity are inputted. 
     By the structure as stated above, in the image forming unit, readout of control data, such as a charge amount, is performed as described below.  FIG. 6  is a flowchart. As shown in  FIG. 6 , a power source is turned ON, or a front cover is opened and closed in order to attach a new toner cartridge (Act  1 ). 
     First, readout is performed from the memory  29 K of the toner cartridge  27 K. The identification code is read from 00h of the memory  29 K, and it is determined whether the identification code is coincident with that of A001 of the memory  28  (Act 2-1). When the identification codes are coincident, the color code K is read from 01h of the memory  29 K, and it is determined whether the color code is coincident with the color code K of A002 (Act 2-2) 
     When the identification codes are not coincident, the display part  32  display an error to that effect (Act 6-1), and the toner cartridge is replaced, or a shift is made to a non-recognition print mode in which control data is not read (Act 6-2). 
     When the color codes are coincident, the reference destination of the control data is read from 02h of the memory  29 K (Act 2-3). 
     At this time, for example, with respect to the toner stored in the toner cartridge  27 K, when a control condition can be calculated by correcting standard data by a specified correction value independently of the temperature and humidity, the reference destination is the memory  28 . In this case, only correction coefficient is read from 03h of the memory  29 K (Act  2 - 4 ). The CPU  31  calculates the control condition from the standard data of A011 of the memory  28  and the correction coefficient of 03h (Act 2-5). 
     On the other hand, in the toner stored in the toner cartridge  27 K, for example, when the correction value for calculating the control condition is changed by the temperature and humidity, the reference destination is the memory  29 K. In this case, all the control data of 04h-FFh are read (Act 2-6). The CPU  31  selects the control condition from the control data based on the temperature and humidity data previously acquired by the temperature and humidity meter  30  and stored in A006 (Act 2-7). 
     The calculated or selected control condition is stored in A007 of the memory  28  (Act 2-8). 
     When the color codes are not coincident, an error to that effect is displayed (Act 7-1), and the toner cartridge is replaced with a correct one (Act 7-2). 
     Similarly, readout from the memory  29 Y of the toner cartridge  27 Y, storage of the control condition (Act 3-1 to Act 3-8), readout from the memory  29 M of the toner cartridge  27 M, storage of the control condition (Act 4-1 to Act 4-8), readout from the memory  29 C of the toner cartridge  27 C, and storage of the control condition (Act 5-1 to Act 5-8) are sequentially performed. 
     The readout from the memories  29 K,  29 Y,  29 M and  29 C of all the toner cartridges  27 K,  27 Y,  27 M and  27 C, and the calculation of the control conditions are ended, the image forming apparatus is placed into the print operation ready state (Act 8). In the respective image forming units  20 K,  20 Y,  20 M and  20 C, the print operations under the respective control conditions stored in A007 to A010 are performed (Act 9). 
     In this way, the selection can be performed such that when the control condition can be corrected by the fixed correction value, only the correction value is read, and when not so, all the control data are read. Accordingly, a readout time of the unnecessary readout can be shortened. 
     For example, as in the related art, when all control data are read, a readout processing time in each of the toner cartridges  27 K,  27 Y,  27 M and  27 C is 1.020 seconds, and a total processing time is 4.080 seconds. On the other hand, when only the correction value is read, the readout processing time of each is 0.060 seconds, and the total processing time is 0.240 seconds. Accordingly, a memory content is not changed from that of the related art, and the readout time can be greatly shortened. The data readout time can be shortened not only in full-color printing but also in monochrome or monocolor printing. 
     In this embodiment, although the control condition is a charging output and a development bias, and the measurement data is the temperature and humidity, no limitation is made to this. For example, the control condition may be a laser output, and the measurement data may be the temperature and humidity. Besides, the control data is made a correction value for the standard data dependent on the measurement data, and the control condition may be calculated by the correction value selected based on the measurement data. 
     Incidentally, by reading intrinsic data of the toner cartridge, such as a serial number of the toner cartridge, it can be determined whether the toner cartridge is a new toner cartridge or is not changed (the same as the toner cartridge at the last printing). When the intrinsic data is coincident with previously read intrinsic data (the same toner cartridge), the correction data is not read, and the control condition stored in A007 of the memory of each toner cartridge can be used as it is. By this, the readout time can be further shortened. 
     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.

Technology Category: 3