Patent Publication Number: US-8970648-B2

Title: Erasing apparatus and decoloring method

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based upon and claims the benefit of priority from U.S. Provisional Patent Application No. 61/612,238, filed on Mar. 16, 2012; the entire contents of which are incorporated herein by reference. 
    
    
     FIELD 
     Embodiments described herein relate generally to an decoloring apparatus that renders un-colored the color of an image created using a developing material, i.e., a coloring material. 
     BACKGROUND 
     The decoloring apparatus carries out erasing of the color of the coloring material (developing material) so as to erase the color of the image and to enable reuse of the paper sheet on which the coloring material has been formed. 
     To erase an image, the decoloring apparatus heats the developed coloring material (developing material) so as to decrease the effect of the developing agent on the coloring compound (the precursor compound of the coloring matter) that causes display of the color under the action of the developing agent. As a result, the coloring state is cancelled. As used herein, color includes a material having a reflected wavelength, when received by the human eye, within the range of wavelengths discernible by the eye as a color, as well as black and white (when formed on a non-white back ground). 
     However, when the thermal capacity of a decoloring apparatus is increased to shorten the warm-up time thereof, the power consumption increases during the decoloring process, because the decoloring process may not require the higher thermal capacity function, resulting heat loss, and thus energy loss, resulting from operating the apparatus at a higher than necessary temperature. On the other hand, where a decoloring apparatus merely has the thermal capability required to maintain the temperature required for the decoloring process, the warm-up time of the apparatus will be too long. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram illustrating an example of an erasing apparatus according to an embodiment. 
         FIG. 2  is a diagram illustrating an example of a main portion of the erasing apparatus according to the embodiment. 
         FIG. 3  is a diagram illustrating an example of the decoloring device of the erasing apparatus according to the embodiment. 
         FIG. 4  is a diagram illustrating an example of an operation in the decoloring process of the erasing apparatus according to the embodiment. 
         FIG. 5  is a diagram illustrating an example of an operation of the decoloring process of the erasing apparatus according to the embodiment. 
         FIG. 6  is diagram illustrating an example of an operation of the decoloring process of the erasing apparatus according to the embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments solve the aforementioned problems of the related art by providing an erasing apparatus and a decoloring method for decoloring the color of the image with a shorter warm-up time less power consumption. 
     In general, embodiments will be explained with reference to the drawings. 
     According to an embodiment, an erasing apparatus comprises a conveying unit that transports a sheet on which a color is developed by a developing material and a decoloring unit that comprises a heating unit that heats up the sheet to decolor (render non-visible) the color. The heat output from the heating unit is variable. 
     As shown in  FIGS. 1 and 2 , an erasing apparatus  101  at least includes a paper feeding unit  10 , an erasing section  20 , a read section  30 , a conveying unit  40  (not shown in  FIG. 1 ), a decoloring device control section  50 , and a paper discharging unit  60 . The erasing apparatus  101  also contains a display section  70  and an operation section  80 , as shown in  FIG. 2 . Here, for example, the display section  70  and the operation section  80  may be formed monolithically by using, e.g., a touch panel, etc.  FIG. 1  is a schematic diagram of the erasing apparatus  101 , illustrating mainly the transportation of sheets (paper sheets) in the erasing apparatus  101  and specifically the circulation of the sheets to a decoloring device  21  disposed at the erasing section  20 .  FIG. 2  is a block diagram illustrating the erasing apparatus  101  shown with its major blocks. 
     The paper feeding unit  10  at least includes a section  11  for holding the sheets before decoloration (hereinafter, a feed paper cassette), a conveying path  41  (conveying unit  40 ), a feed paper roller  12 , a conveying roller  13 , and a conveying roller  14 . The feed paper cassette  11  holds the sheet (paper sheet) that has an image (coloring material), which is the object of the decoloration operation. Thus, the sheet that has not yet been decolored is stored at the feed paper cassette  11 . The conveying path  41  (included in conveying unit  40  in  FIG. 2 ) is formed to guide the still colored sheet held in the feed paper cassette  11  to the erasing section  20 . The feed paper roller  12  applies a pushing force (transporting force) on the still decolored sheet so that the sheet can be transported (driven to move) to the conveying path  41 . 
     The conveying path  41  is connected to a conveying path  42  (included in conveying unit  40  in  FIG. 2 ), which is formed in the read section  30 . 
     The conveying path  42  (conveying unit  40 ) is formed to guide the still colored sheet to the erasing section  20 . At the erasing section  20 , the color of the image on the sheet is erased (i.e., the color of the coloring material is decolored to be invisible or substantially invisible to the human eye). The sheet (discolored sheet) is guided to the paper discharging unit  60 . Along the conveying path  42 , at least conveying rollers  33  and  34  are provided, and the conveying rollers  33  and  34  apply a pushing force on the pre-discolored sheet and the decolored sheet so that these sheets can be transported through the conveying path  42 . 
     The erasing section  20  at least includes a decoloring device  21 , a branching unit  22 , a conveying path  47  (included in conveying unit  40  in  FIG. 2 ), and conveying rollers  23  through  28 . The branching unit  22  faces a decoloring device  21  and branches a still-discolored sheet from the conveying path  42  based on the reading result by the read section  30  that the sheet contains an image thereon and directs it to the conveying path  47 . The conveying path  47  guides the pre-discolored sheet to the decoloring device  21 . The conveying rollers  23  through  25  provide a pushing force on the still-discolored sheet so that it can be transported to the decoloring device  21 . The conveying rollers  26  through  28  guide the sheet decolored or “erased” at the decoloring device  21  back to the conveying path  42 . 
     The decoloring device  21  contains a first heating unit  210  and a second heating unit  220 . Both of the first heating unit  210  and the second heating unit  220  may apply heat at a decoloring temperature, which is over a prescribed temperature to decolor or erase the image, on the sheet passing through prescribed nip regions. The prescribed nip region is a portion formed between a pair of rollers that are included in a single heating unit ( 210  or  220 ). 
     The decoloring device  21  will be explained in detail later with reference to  FIG. 3 . 
     The read section  30  ( FIG. 1 ) includes at least a first image sensor  31  ( FIG. 1 ) and a second image sensor  32  ( FIG. 1 ), both of which detect whether the sheet that passes through the conveying path  42  needs to be decolored, i.e., whether the sheet has an image thereon. The first image sensor  31  and the second image sensor  32  may be made of, e.g., reflective density sensors or dielectric constant measurement sensors, etc., and they detect the images on both surfaces of the sheet that passes through the conveying path  42 . 
     The first image sensor  31  and the second image sensor  32  of the read section  30  may be CMOS sensors, for example, and they may acquire the image information of the sheet that passes through the conveying path  42 . The image information acquired by the first and the second image sensors  31  and  32  is stored in a memory device  36 , as shown in  FIG. 2 . The image information stored in the memory device  36  is subject to A-D conversion (analog/digital conversion), and the converted information is sent to a page memory  35  in page unit. 
     The conveying path  42  is connected to a conveying path  43  at the branching unit  22  that guides a decolored sheet selected by the branching unit  22  to the paper discharging unit  60 . 
     Along the conveying path  43  (included in the conveying unit  40  in  FIG. 2 ), at least a discharged paper branching unit  16  and a conveying roller  15  are disposed. The discharged paper branching unit  16  branches the decolored sheet branched by the branching unit  22  to either a first decolored sheet holding section (hereinafter a reusing cassette)  61  or a second decolored sheet holding section (hereinafter a stocker)  62  of the paper discharging unit  60 . The decolored sheet that is branched toward the reusing cassette  61  is guided by a conveying roller  63  that is disposed along a conveying path  44  (included in the conveying unit  40  in  FIG. 2 ). Also, the decolored sheet that is branched toward the stocker  62  is guided by the conveying rollers  64  and  65  and conveying paths  45  and  46  (both are included in the conveying unit  40  in  FIG. 2 ). 
     In addition, a structure to manually feed a pre-discolored sheet to the decoloring device  21  is provided. The structure included a manual paper feeding unit  17  and a conveying roller  18  that is disposed along a manual feeding conveying path  48 . A pre-discolored sheet fed from the manual paper feeding unit  17  passes through the manual feeding conveying path  48  and is guided to the conveying path  42  by the conveying roller  18 . Thus, this pre-discolored sheet does not pass through the conveying path  41 . 
     The control section  50  includes at least a Central Processing Unit (CPU) (or principal controller)  51 , a Read-Only Memory (ROM)  52 , a Random Access Memory (RAM)  53 , an input/output (I/O) port  54 , a motor driver  56 , a conveying path switching control section (branching unit drive section)  57 , a temperature control section  58 , a power supply section  59 , etc. Here, the operation section  80  and the display section  70  are connected to the control section  50 . Also, the motor driver  56  drives a transport motor  29  that drives the conveying rollers  23  through  28  located at the upstream or the downstream of the decoloring device  21  and drives any other motors that drive the other rollers, for example. 
     The principal controller (CPU)  51  controls the operations of the various sections according to operation programs stored in the ROM  52 . 
     The ROM  52  stores the operation programs for the operation of the decoloring device  21 , as well as the reference data that are used to compare with the detection results detected by the first and the second image sensors  31  and  32 , etc. 
     The RAM  53  receives and stores the data input through the I/O port  54 , such as the detection results of the first and the second image sensors  31  and  32 , the inputs from JAM sensors that are disposed at prescribed positions along the conveying paths  41  through  48 , as well as the temporary data for executing the processing routine according to the instruction input (operation information) from the operation section  80 . 
     For example, the I/O port  54  converts the detection results of the first and the second image sensors  31  and  32  to a format that can be processed by the CPU (principal control section)  51 . The I/O port  54  also converts the instruction input from the operation section  80  to a format that can be processed by the CPU  51 . The I/O port  54  also works to receive the information related to the paper feeding unit  10 , the erasing section  20 , the read section  30 , the conveying unit  40 , and the paper discharging unit  60 , e.g., the control instructions to the motors and the branching unit and the detected data of any sensors, etc. 
     In the paper discharging unit  60 , the decolored sheet, going through the conveying path  43  as shown in  FIG. 1 , is guided by the discharged paper branching unit  16  to either the reusing cassette (first decolored sheet holding section)  61  or the stocker (second decolored sheet holding section)  62 . 
     The operation section  80  receives the control instruction from input, e.g., the user, and outputs a control command corresponding to the control instruction in a format readable by the CPU  51 . 
     As shown in  FIG. 1 , the decoloring device  21  is located at a prescribed position along the conveying path (a second conveying path)  47 . The conveying path  47  branches just after the read section  30  (conveying path  42 ) from the first conveying path, and is comprised of the conveying path  41 , the conveying path  42  (read section  30 ), the conveying path  43 , the conveying path  44  (paper discharging unit  60 ), the conveying paths  45  and  46  that are located between [the portion and] the reusing cassette  61  and the stocker  62 . 
     As shown in  FIG. 3 , the decoloring device  21  includes the first heating unit  210  and the second heating unit  220 . The side or location of the conveying rollers  23 ,  24 , and  25  of the conveying path  47  with respect to decoloring device is defined as the transporting upstream side. On the other hand, the side of the conveying rollers  26 ,  27 , and  28  of the conveying path  47  with respect to decoloring device is defined as the transporting downstream side. 
     The first heating unit  210  is disposed close to the transporting upstream side and includes a pair of rollers, i.e., a heating roller  211  and a pressing roller  212 . A heat source lamp  213  is disposed inside the heating roller  211 , and a temperature detecting section  214  is disposed adjacent the outer periphery of the heating roller  211 . 
     The second heating unit  220  is spaced from the first heating unit  210  and is disposed close to the transporting downstream side and includes a pair of rollers, i.e., a heating roller  221  and a pressing roller  222 . A first heat source lamp (hereinafter a main lamp)  223  and a second heat source lamp (hereinafter a sub-lamp)  224  are disposed inside the heating roller  221 , and a temperature detecting section  225  is disposed adjacent to the outer periphery of the heating roller  221 . 
     The thermal capacity of the heat source lamp  213  is nearly equal to the sum of the thermal capacities of the main lamp  223  and sub-lamp  224 . The thermal capacity of the main lamp  223  and that of the sub-lamp  224  are nearly equal to each other. 
     The heating rollers  211  and  221  are disposed so that both sides of the sheet passing through the heating rollers  211  and  221  contact with the heating rollers  211  and  221 . In the configuration of the embodiment, the heating roller  211  is in contact with one surface (outer periphery, or the second image sensor  32  side) of the sheet passing through the second conveying path. Consequently, the heating roller  221  is in contact with the other surface (inner periphery, or the first image sensor  31  side) of the sheet passing through the second conveying path. 
     The first heating unit  210  and/or the second heating unit  220  each may have a nip formed from a roller and an endless belt. The heat source lamp  213  of the first heating unit  210  or the main lamp  223  and sub-lamp  224  of the second heating unit  220  may be IH (inductive heating) heaters that generate inductive heat by the metal surface of the heating roller (or the metal layer of the belt) for example. 
     In the following, the transporting operation will be explained. 
     In a decoloring and read mode, the pre-discolored sheet, which is a sheet on which the coloring material is developed, is fed from the paper feeding unit  10  through the first conveying path [ 11 ], as shown in  FIG. 4 . Then, the sheet is positioned at the read section  30  [ 12 ]. At the read section  30 , the first and the second image sensors  31  and  32  read image information on the sheet from both sides. The image information on the sheet read by the first and the second image sensors  31  and  32  is then stored at the memory device  36 . 
     After passing through the read section  30 , the sheet is guided through the second conveying path (conveying path  47 ) to the decoloring device  21  [ 13 ]. Then, the sheet is subject to the decoloring process to decolor the color of the image [ 14 ]. During the decoloring process, the sheet passes the conveying roller  25  disposed on the transporting upstream side and then goes between the two rollers of the first heating unit  210  and then between the two rollers of the second heating unit  220  disposed on the transporting downstream side. 
     The sheet that has been decolored by the decoloring device  21  is guided by the conveying roller  26  disposed on the transporting downstream side through the second conveying path [ 15 ]. The decolored sheet in the second conveying path is once again guided to the first conveying path and discharged to the reusing cassette (a first discharged paper tray)  61  or the stocker (a second discharged paper tray)  62  of the paper discharging unit  60 . 
     Here, when the decoloring process is carried out by the decoloring device  21 , the second heating unit  220  (i.e., the heat source section on the transporting downstream side) conducts the decoloring process on a sheet that has been already heated by the first heating unit  210  (i.e., the heat source section on the transporting upstream side). Consequently, the heat that the second heating unit  220  is required to provide to the sheet is lower than the heat that the first heating unit  210  is required to provide to the sheet. Thus, the heat quantity needed to carry out the decoloring process at the second heating unit  220  is smaller. On the other hand, if the second heating unit  220  discharges the same amount of heat as the first heating unit  210 , the excessive heat by the second heating unit  220  results in waste of energy resulting in non-recovered cost. 
     On the other hand, the second heat unit  220  is preferred to have a larger thermal capacity when the decoloring device  21  is in a warm-up process, to rapidly heat the decoloring device. Thus, if the second heating unit  220  is a heat source section with a lower thermal capacity, the time needed for the heating roller  221  to reach the decolorable temperature may become longer. Here, the warm-up process refers to the process executed for the heat source section  221  (heating roller) to reach the decolorable temperature. 
     To save heat during the decoloring process and to save warm-up time during the warm-up process, the heat source of the heat source section on the transporting downstream side (i.e., the second heating unit  220 ) is configured to have two lamps, that is, the main lamp  223  and the sub-lamp  224 . As shown in  FIG. 5 , in a warm-up mode [ 21 —YES], both the main lamp  223  and the sub-lamp  224  are turned on, so that the temperature of the heat source section (heating roller)  221  can quickly reach the decolorable temperature [ 22 ]. 
     On the other hand, when decoloring process is carried out for the color of the image on the sheet [ 21 —NO], only the main lamp  223  of the second heating unit  220  is turned on [ 23 ], and the decoloring process is carried out [ 24 ]. 
       FIG. 6  is a diagram illustrating another example of control of the lamps (heat sources) adopted in the decoloring process, in which either the main lamp  223  or the sub-lamp  224  alone is turned on. 
     If either the main lamp  223  or the sub-lamp  224  alone is turned on to carry out the decoloring process, the lamps will soon run over the warranty time (lifetime) because only one lamp is turned on. In order to replace the run-out lamp, the entire second heating unit  220  may need to be replaced. 
     Consequently, it is preferred to turn on the lamp different from the lamp that was turned on in the last round of the decoloring process. However, because lamp life is at least in part a function of the number of times the lamp is switched on and off, it is preferred to use the same lamp so long as a series of sheets is present and ready to be decolored. 
     For example, if the lamp that was turned on in the decoloring process in the last round (the preceding round) is the main lamp  223  [ 31 —YES], the sub-lamp  224  is turned on in the next round (the following round) of decoloring process [ 32 ], and the decoloring process is carried out [ 33 ]. A round is considered a period where decoloring is occurring and at least one sheet is present in the input of the system for analysis and decoloration if appropriate. 
     Also, if the lamp that was turned on in the last round of decoloring process is the sub-lamp  224  [ 31 —NO], the main lamp  223  is turned on [ 34 ] in the next round (the following round) of decoloring process, and the decoloring process is carried out [ 33 ]. 
     In the control operation as shown in  FIG. 6 , the lamp to be turned on may be switched in each round of the decoloring process. However, it takes a certain time to heat up a non-heated roller to the decolorable temperature, because the efficiency for heating up the lamp from the cold state to the hot state is poor. Consequently, as long as a pre-discolored sheet is prepared at the feed paper cassette or the manual paper feeding unit  17 , the same lamp is preferred to be used (turned on). Thus, even when the sheets for decoloration are one sheet for a job, the same lamp is preferred to be kept ON (in use) if there is the next sheet to feed (paper feeding). Therefore, switching of the heat source lamp that is turned on is preferably not carried out. 
     With the above-mentioned configuration, the optimum heat quantity can be applied to the sheet or the coloring material as the decoloration object, and it is possible to prevent degradation in performance and increase in power consumption. 
     Also, it is possible to prolong the lifetime of the device. 
     Though the erasing apparatus shown in  FIGS. 1 to 3  has the reading section  30  to select the sheets to be decolored, the read section  30  may be omitted. In this case, decoloration is carried out for all of the sheets that have been fed into the erasing apparatus regardless of whether the have an image thereon. 
     According to the embodiment, the decoloring apparatus can avoid shortening of the lifetime of the apparatus (heat source lamps), can shorten the warm-up time, and can cut the cost of the apparatus and the power consumption. 
     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 omissions, 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.