Abstract:
There is provided an image forming device that includes a conveyor section, an image forming section, an accessing section and a control unit. The conveyor section conveys recording media in a conveying path, the recording media including a recording medium having a data storage unit attached thereto and a recording medium with no data storage unit attached thereto, the data storage unit storing data or being capable of storing data. The image forming section forms an image on the recording medium. The accessing section is disposed at an access position along the conveying path and accesses the data storage unit to execute an access operation to write data into or read data from the data storage unit. The control section is configured to control the conveyor section and the accessing section to bring the recording medium having passed the access position back to the access position and to access the data storage unit attached to the recording medium which has brought back to the access position to execute a re-access operation to write unprocessed data into or read unprocessed data from the data storage unit, the unprocessed data being such data that remained unprocessed with the access operation.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims priority from Japanese Patent Application No. 2008-277128 filed Oct. 28, 2008. The entire content of the priority application is incorporated herein by reference. 
     TECHNICAL FIELD 
     The present invention relates to an image forming device, and more particularly to an image forming device capable of writing or reading data stored in a storage unit attached to a recording medium, such as an RFID (Radio Frequency IDentification). 
     BACKGROUND 
     There has been provided an image forming device that can write or read data stored in an IC chip (storage unit) called RFID attached to a recording medium when forming images on the recording medium. Such a conventional image forming device is able to re-convey the recording medium for re-accessing the IC chip even if a try to access the IC chip has once failed. However, even though the recording medium is brought back to re-access the data in the IC chip, if the IC chip stores too much information to be accessed at a time, such a re-try tends to result in another failure. 
     SUMMARY 
     In view of the foregoing, it is an object of the present invention to provide an image forming device capable of enhancing a probability that the image forming device can successfully complete an access to data in a storage unit attached to a recording medium. 
     In order to attain the above and other objects, there is provided an image forming device that includes a conveyor section, an image forming section, an accessing section and a control unit. The conveyor section conveys recording media in a conveying path, the recording media including a recording medium having a data storage unit attached thereto and a recording medium with no data storage unit attached thereto, the data storage unit storing data or being capable of storing data. The image forming section forms an image on the recording medium. The accessing section is disposed at an access position along the conveying path and accesses the data storage unit to execute an access operation to write data into or read data from the data storage unit. The control section is configured to control the conveyor section and the accessing section to bring the recording medium having passed the access position back to the access position and to access the data storage unit attached to the recording medium which has brought back to the access position to execute a re-access operation to write unprocessed data into or read unprocessed data from the data storage unit, the unprocessed data being such data that remained unprocessed with the access operation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings: 
         FIG. 1  is a block diagram briefly showing an electric configuration of a printer as an example of an image forming device according to a first embodiment of the present invention; 
         FIG. 2  is a cross-sectional view illustrating a general configuration of the printer according to the first embodiment; 
         FIGS. 3 and 4  are a flowchart explaining flows of a print routine executed at the printer according to the first embodiment; 
         FIG. 5  is a cross-sectional view illustrating a general configuration of a printer as an example of an image forming device according to a second embodiment of the present invention; and 
         FIG. 6  is a flowchart explaining flows of a print routine executed at the printer according to the second embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     First, a printer  1  according to a first embodiment of the present invention will be described with reference to  FIGS. 1 to 4 . 
     As shown in  FIG. 1 , the printer  1  includes a CPU  11 , a ROM  12 , a RAM  13 , an NVRAM  14 , a network interface  15 , an image forming unit  17 , an IC reader-writer  18 , a display unit  19 , an operation unit  20  and a conveyor unit  21 . 
     The ROM  12  stores programs necessary for executing various operations including a print routine (to be described later). The CPU  11  controls each unit of the printer  1  in accordance with programs read from the ROM  12 , while instructing the RAM  13  or the NVRAM  14  to store necessary processing results or data. The network interface  15  is connected to an external computer (not shown) via a network so that the printer  1  can communicate with the external computer. 
     The image forming unit  17  forms images on sheets  25  (shown in FIG.  2 ) using one or a plurality of colorants (ink or toner). The IC reader-writer  18  communicates with an RFID tag incorporated into the sheet  25 , using radio waves, without contact. The IC reader-writer  18  is so configured as to be able to either read data stored in the RFID tag or write data into the RFID tag. Alternatively, the IC reader-writer  18  may be so configured as to be able to both read and write data. Such reading and writing operations performed by the IC reader-writer  18  are to be called as an ‘access operation’ hereinafter. 
     The display unit  19  is provided with a lamp and a display on which various set-up screens and operating states of each unit are configured to be displayed. The operation unit  20  includes a plurality of buttons with which a user can input various commands. 
     As shown in  FIG. 2 , the conveyor unit  21  includes a plurality of rollers, a belt unit  21 A for conveying the sheets  25 , and a switchback mechanism  21 B (to be described later). Although not shown in  FIG. 2 , the belt unit  21 A is also provided with a motor as a driving source and a gear mechanism that transmits driving force of the motor to the rollers. 
     As also shown in  FIG. 2 , the printer  1  includes a sheet accommodation tray  26  in which a plurality of sheets  25  are stacked, and a discharge tray  27  formed on an upper surface of the printer  1 . Note that the sheets  25  may or may not be provided with RFID tags. The conveyor unit  21  conveys an uppermost sheet of the stack of the sheets  25  at a time to a sheet conveying path A, then to a sheet conveying path B, and subsequently to a sheet conveying path C. Each sheet  25  is finally discharged onto the discharge tray  27  from the sheet conveying path C. However, whenever necessary, some sheets  25  are returned to the sheet conveying path B from the sheet conveying path C, via a sheet conveying path D, by the switchback mechanism  21 B. The switchback mechanism  21 B switchbacks the sheet  25  and thus reverses a sheet conveying direction thereof to bring the sheet  25  back to the access position P 1  via the sheet conveying path D. 
     Along the sheet conveying path B, the IC reader-writer  18  and the image forming unit  17  are disposed. Specifically, the IC reader-writer  18  is located upstream, and the image forming unit  17  is located downstream of the sheet conveying path B. In the sheet conveying path B, a portion opposing the IC reader-writer  18  will be referred to as an ‘access position P 1 ’ at which the IC reader-writer  18  can access the RFID tags, while a portion opposing to the image forming unit  17  will be referred to as an ‘image forming position P 2 ’ at which the image forming unit  17  can form images on the sheets  25 . 
     As above described, the sheet conveying path A and B serve to convey the sheet  25  to the access position P 1  and the image forming position P 2 , while the sheet conveying path D serves to bring the sheet  25  back to the access position P 1  for the re-access operation. 
     Next, a print routine executed by the CPU  11  will be described with reference to a flowchart of  FIGS. 3 and 4 . 
     Upon receipt of a command requesting to execute printing via the network interface  15  from an external computer, the CPU  11  initiates the print routine shown in  FIGS. 3 and 4 . 
     Note that, when transmitting such a print command from an external computer, a user may specify various print conditions (such as double-sided or single-side; in color or in monochrome), instructions relating to accessing the RFID tags (such as instructions to read or write data), and instructions on contents to be written. All these instructions will be collectively referred to as an ‘access instruction.’ The print command includes such information on the print conditions and the access instructions. Alternatively, the user may input the print command and various settings from the operation unit  20 . In this case, the print routine is configured to be executed based on the user&#39;s inputs. 
     As shown in  FIG. 3 , upon starting the print routine, the CPU  11  first determines whether there is an access instruction to an RFID tag (S 101 ). If an access to the RFID tag is not instructed (S 101 :No), the CPU  11  executes printing without accessing the RFID tag (S 102 ), and subsequently terminates the print routine. 
     On the other hand, if an access to the RFID tag is requested (S 101 :Yes), the CPU  11  sets a value of a counter to zero, the counter being for counting numbers of times the sheet  25  is re-conveyed (i.e., how many times the sheet  25  is flipped) (S 103 ). The CPU  11  then instructs the conveyor unit  21  to start conveying the sheet  25  accommodated in the sheet accommodation tray  26  (S 104 ). The CPU  11  then executes an access operation against the RFID tag attached to the sheet  25  while the sheet  25  passes the access position P 1  (S 105 ). Access operations executed here by the CPU  11  include: reading data such as authentication information stored in the RFID tags; and writing data such as a user name, printed time, print conditions and setting information. Additionally, image data to be printed may be written into the RFID tags. 
     The CPU  11  then determines whether the RFID tag is attached to the sheet  25  to which the CPU  11  executed the access operations (S 106 ). If the RFID tag is determined not to be attached, i.e., if there is no reply from the RFID tag (S 106 :No), the CPU  11  instructs the conveyor unit  21  to convey the sheet  25  from the sheet conveying path B to the sheet conveying path C. The conveyor unit  21  then discharges the sheet  25  onto the discharge tray  27  without forming images thereon (S 107 ). The print routine is then terminated. 
     As a variation, the IC reader-writer  18  may be configured to transmit a signal to detect existence of RFID tag before starting an access operation. In this case, if there is no response from the RFID tag, i.e., if the RFID tag is not detected, the CPU  11  may cancel executing the access operation. 
     If the RFID tag is determined to be attached (S 106 :Yes), the CPU  11  then determines whether access operations have completed successfully (S 108 ). In other words, the CPU  11  determines whether all the data to be read have actually been read or all the data to be written have actually been written. 
     More specifically, for example, the CPU  11  may be configured to read data for a plurality of times and then to check consistency among the read data during one access operation. If any inconsistency exists among the read data or any portion of the data is left unread, the CPU  11  designates such data as being ‘unprocessed,’ determining that the access operation to the data has not successfully ended. 
     Alternatively, data to be written into the RFID tag is divided into a plurality of blocks and is written thereinto on a block-by-block basis. In order to determine that the access operation (writing operation in this case) has been successfully completed, each block data written into the RFID tag is retrieved therefrom and the resultant block data is compared with the corresponding original data block. This comparison is performed with respect to all the blocks of data during one access operation. If there is an inconsistency between the retrieved block data and the corresponding original block data or if writing or retrieving any block data has not finished during one access operation, such block data is treated as being ‘unprocessed’ and determination is made so that the access operation has not successfully ended. If this is the case, retry is implemented as will be described later. 
     As a further alternative, an amount of total data to be read may be recorded at a header portion of each RFID tag. In this case, the CPU  11  may determine that an access operation to the data has not yet been ended if an amount of data read by the IC reader-writer  18  does not cover the amount of the total data. 
     Returning to the flowchart of  FIG. 3 , when an access operation is determined not to have ended (S 108 :No), the CPU  11  then determines whether the value of the counter reaches a predetermined maximum value (upper limit) (S 109 ). The maximum value is set to be greater than two (2) in the present embodiment. If the value of the counter does not reach the maximum value (S 109 :No), the CPU  11  instructs the switchback mechanism  21 B to switchback the sheet  25  and to re-convey the sheet  25  to the access position P 1  from the sheet conveying path C via the sheet conveying path D (S 110 ). The CPU  11  then increments the value of the counter by one (S 111 ). 
     Subsequently, the CPU  11  executes another access operation to the ‘unprocessed’ data when the RFID tag of the sheet  25  comes back to the access position P 1  (S 112 ). The flows S 110 -S 112  executed by the CPU  11  are called as a ‘re-access operation.’ 
     More precisely, in the re-access operation, the CPU  11  may instruct the RFID tag to transmit the ‘unprocessed’ data which have not yet been read in the previously-executed access operation. Upon receipt of the unprocessed data from the RFID tag, the CPU  11  adds the received data to data which have already been read and stored in the RAM  13  as a result of the previous access operation. Alternatively, the CPU  11  may instruct the IC reader-writer  18  to transmit ‘unprocessed’ data which have not yet been written in the previous access operation to the RFID tag. Upon receipt of the unwritten data, the RFID tag may add the same to data which have already been written and thus stored therein in the previous access operation. 
     In this way, the CPU  11  is configured not to repeat an access operation to data that have been successfully read or written in a preceding access operation. With this configuration, compared to a case where all the data are repeatedly accessed to each time, amounts of data to be re-accessed can be reduced, thereby leading to an increase in a probability of successfully completing an access operation to the data at the time of re-accessing. This configuration is especially effective when most of the data have been successfully read or written in an access operation executed for the first time. 
     Further, this configuration can realize at a higher probability that an access operation to the RFID tag ends successfully, not only if an amount of data to be accessed is large for one access operation, but also if communications between the IC reader-writer  18  and the RFID tag has failed because of some noise. 
     Once finishing the re-access operation at S 110 -S 112 , the CPU  11  then returns to S 108  and again determines whether the access operation has been properly completed. If the access operation is determined not to have been completed yet (S 108 :No), the re-access operation is configured to be repeated until the value of the counter reaches the upper limit thereof (S 109 -S 112 ). When the counter value reaches the upper limit (S 109 :Yes), the CPU  11  instructs the conveyor unit  21  to discharge the sheet  25  subject to the re-access operation (S 113 ) and terminates the print routine. 
     In other words, when the upper limit is set to be greater than or equal to 2, the re-access operation is configured to be repeated for a plurality of times unless the access operation has completed successfully. 
     Now referring to  FIG. 4 , when the access operation ends successfully (S 108 :Yes), the CPU  11  determines whether a double-sided printing is instructed in the print command as a print condition (S 114 ). If a single-side printing is designated (S 114 :No), the CPU  11  then determines whether the value of the counter is an even number (S 115 ). If the counter value is an odd number (S 115 :No), the CPU  11  instructs the switchback mechanism  21 B to bring the sheet  25  back to the access position P 1  (S 116 ). The CPU  11  subsequently instructs the image forming unit  17  to form an image for front surface on a side (which will be a front side) of the sheet  25  when the sheet comes to the image forming position P 2  (S 117 ). On the other hand, if the counter value is an even number (S 115 :Yes), the CPU  11  instructs the image forming unit  17  to form the front surface image on the front side of the sheet  25  without re-conveying the sheet  25 , when the sheet  25  arrives at the image forming position P 2  (S 117 ). 
     With this configuration, regardless of the value of the counter being an even or odd number, a front surface image can be formed on a front side of each sheet  25 . Note that the front surface image is configured to be formed on the side (i.e., the front side) of the sheet  25  that faces downward in the sheet accommodation tray  26 . 
     The CPU  11  then discharges the sheet  25  having the image formed on the front side thereof out of the printer  1  via the sheet conveying path C (S 118 ) and terminates the print routine. In this way, each of the discharged sheets  25  is stacked in the discharge fray  27  with the printed surface facing downward (in a face-down state). Even if the single-side printing is to be executed on a plurality of sheets  25 , front surface images are formed on the side (front side) of each sheet  25  facing downward in the sheet accommodation tray  26  and each of the printed sheets  25  is discharged onto the discharge tray  27  in the face-down state. 
     If the double-sided printing is instructed in the print command (S 114 :Yes), the CPU  11  determines whether the value of the counter is an even number (S 119 ). If the counter value is an even number (S 119 :Yes), the CPU  11  re-conveys the sheet  25  to the access position P 1  using the switchback mechanism  21 B (S 120 ) and then instructs the image forming unit  17  to form an image for back surface on a side of the sheet  25  currently facing upward when the sheet  25  reaches the image forming position P 2  (S 121 ) If the counter value is an odd number (S 119 :No), the CPU  11  instructs the image forming unit  17  to form the back surface image on the currently upward surface of the sheet  25 , without re-conveying the sheet  25 , when the sheet  25  arrives at the image forming position P 2  (S 121 ). The CPU  11  then re-conveys the sheet  25  (S 122 ), forms the image for front surface on another side of the sheet  25  facing currently upward when the sheet  25  reaches the image forming position P 2  ( 117 ), and discharges the sheet  25  in a state where images have been formed on both sides of the sheet  25  (S 118 ). The print routine is subsequently terminated. 
     With this configuration, no matter how many times the sheet  25  is reversed, the back surface image is formed on the surface of each sheet  25  facing upward in the sheet accommodation tray  26 , while the front surface image on the other surface of each sheet  25  facing downward in the sheet accommodation tray  26 . Even if the double-sided printing is to be executed on a plurality of sheets  25 , this configuration holds true: the front surface images are formed on each front surface of the sheets  25  facing downward in the sheet accommodation tray  26 , while the back surface images are formed on the other surface (back surface) of the sheets  25  facing upward in the sheet accommodation tray  26 . Each sheet  25  is finally discharged onto the discharge tray  27  with the front surface facing downward. 
     As a variation, if both sides of the sheet  25  need not to be distinguished, the steps where the sheet  25  is re-conveyed in accordance with the number of times the sheet  25  is reversed (S 115 , S 116 , S 119 , S 120 ) may be omitted in the print routine. 
     Note that, in a conventional image forming device not configured to execute re-access operations, a speed at which each sheet is conveyed may be slowed down to make time for accessing an RFID tag in order to complete each access operation at a time. However, with the above-described configuration of the present embodiment in which a re-access operation is carried out only to ‘unprocessed’ data, each access operation is not necessarily to be completed at one time and therefore the speed needs not to be slowed down. Accordingly, a printing operation can end in a short time in case that only one access operation is performed. 
     Further, in the present embodiment, re-access operations are to be repeated for a plurality of times unless the access operation to the sheet  25  is successfully completed. Hence, such a configuration also contributes to a success in the access operation at a higher rate. 
     Further, when the value of the counter reaches the upper limit thereof, i.e., if re-access operations to data are repeated for a plurality of times but accessing the data have not completed yet, the sheet  25  is configured to be discharged. In this way, even if the access operation to the data cannot end normally for some reason (due to a failure of an IC chip, for example), endlessly repeating the re-access operations to the same data can be prevented. 
     Further, if the RFID tag is not attached to the sheet  25 , the sheet  25  is to be discharged without re-access operations thereto being executed. With this configuration, unnecessary re-access operations can be prevented from being executed to sheets having no RFID tags. 
     Moreover, an image is formed on the sheet  25  only if the access operation to the sheet  25  ends successfully. In other words, if image forming has been done on the sheet  25  but the access operation thereto has failed, colorants used for the image forming and the sheet  25  itself may become nothing but a waste. However, in the present embodiment, an image is to be formed on the sheet  25  after the access operation to the sheet  25  has been successfully completed, thereby reliably avoiding producing such a waste. 
     When images are formed on a plurality of sheets  25 , each sheet  25  is discharged in a state where the values of the counter for each sheet  25  can all be even or odd numbers. With this configuration, regardless of the numbers of times each sheet  25  is reversed, each sheet  25  is always discharged in the face-down state, i.e., the front surface downward and the back surface upward in the discharge tray  27 . Note that the sheets  25  may be discharged in a face-up state, instead of the face-down state. In any case, a user does not need to manually flip sides of each sheet  25  to organize the discharged sheets  25 . 
     Further, when an image needs to be formed on a front surface of each sheet  25 , the numbers of times each sheet  25  has been flipped are all set to be even or odd numbers. Hence, regardless of the values of the counter being even or odd numbers, a front surface image is reliably formed on the front side of each sheet  25 . 
     Next, a second embodiment of the present invention will be described with reference to  FIGS. 5 and 6 . Note that in the following description, like parts and components are designated by reference numerals the same as the first embodiment to avoid duplicating description. 
     First, a general configuration of a printer  2  according to the second embodiment is described with reference to  FIG. 5 . The printer  2  is different from the printer  1  in that the printer  2  includes an IC reader-writer  18 A facing the sheet conveying path D. The IC reader-writer  18 A has a flat shape in a vertical direction and is interposed between the sheet accommodation tray  26  and the belt unit  21 A. In the printer  2 , therefore, an access position P 3  where the IC reader-writer  18 A can access the RFID tags of the sheets  25  is located along the sheet conveying path D at a position opposing the IC reader-writer  18 A. 
     Referring to  FIG. 6 , a routine for executing a single-side printing at the printer  2  will be described next. 
     Upon a print operation being initiated, the CPU  11  first sets the value of the counter to zero (S 201 ) and then starts conveying the sheet  25  from the sheet accommodation tray  26  (S 202 ). When the sheet  25  comes to the image forming position P 2 , the CPU  11  instructs the image forming unit  17  to form an image on the sheet  25  (S 203 ). Subsequently, the CPU  11  re-conveys the sheet  25  (S 204 ), increments the value of the counter by one (S 205 ) and instructs the IC reader-writer  18 A to access the RFID tag of the sheet  25  (S 206 ). 
     The CPU  11  then determines whether the access operation has been successfully completed (S 207 ). As long as the access operation has not yet finished (S 207 :No) and the counter value does not reach the upper limit thereof (S 208 :No), the CPU  11  continues to bring the sheet  25  back to the access position P 3  (S 209 ), adds one to the counter value (S 210 ) and instructs the IC reader-writer  18 A to try accessing the ‘unprocessed’ data again (S 211 ). In this way, unless the access operation has finished successfully, the CPU  11  repeats S 208 -S 211  until the counter value reaches the maximum number thereof. Once the access operation has successfully ended (S 207 :Yes), or if the value of the counter reaches the upper limit thereof (S 208 :Yes), the CPU  11  discharges the sheet  25  onto the sheet accommodation tray  26  and terminates the print routine. 
     In the second embodiment, the IC reader-writer  18 A is disposed along the sheet conveying path D. Hence, compared to the first embodiment where the IC reader-writer  18  and the image forming unit  17  are disposed along the sheet conveying path B, the printer  2  can be made compact with respect to the front-to-rear direction (i.e., the sheet conveying direction). Therefore, the front-to-rear dimension of the printer  2  can be made shorter, while enabling the area of the access position P 3  to be greater in the front-to-rear direction. As a result, the IC reader-writer  18 A can have longer time to complete each access operation to the RFID tags, leading to an improved probability of successfully finishing access operations each time. 
     As a variation, instead of the single-side printing, a double-sided printing may be executed in the second embodiment. 
     While the invention has been described in detail with reference to the specific embodiments thereof, it would be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention. 
     For example, the present invention may be applied to image forming devices of various kinds, such as electrophotographic image forming devices, inkjet image forming devices, and image forming devices that print in black and white only. Further, the present invention is also applicable to an image forming device without a belt unit and to an image forming device provided with scanning and facsimile functions. 
     Further, in the access operation according to the present invention, the IC reader-writers  18  and  18 A can read data stored in the RFID tags and write data into the RFID tags. However, the IC reader-writers  18  and  18 A may also be configured to perform either reading or writing data only. Alternatively, a plurality of access positions may be provided in an image forming device. If this is the case, such an image forming device may be configured to read data at some access positions, while write data at other access positions.