Abstract:
A detection system includes: an acquiring unit that acquires document data representative of a document which includes a plurality of pages; a selector that selects, for each page of the document, a first printing sheet which contains a detected element or a second printing sheet which does not contain the detected element such that the first printing sheet is selected for at least one page; a supplier that supplies the first or the second printing sheet selected by the selector; a printer that sequentially prints the document acquired by the acquiring unit on the printing sheets supplied by the supplier; a detector that detects a detected element contained in a printing sheet on which the document is printed by the printer; and a reporter that reports detection of the detected element in a printing sheet by the detector.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2007-152901 filed on Jun. 8, 2007. 
     BACKGROUND 
     1. Technical Field 
     The present invention relates to technology for insuring the security of a printed document. 
     2. Related Art 
     A confidential document should be protected from being copied and taken out of a controlled area without permission. As technology for preventing unauthorized taking out of a printed document is known. 
     SUMMARY 
     According to an aspect of the invention, there is provided a detection system including: an acquiring unit that acquires document data representative of a document which includes a plurality of pages; a selector that selects, for each page of the document, a first printing sheet which contains a detected element or a second printing sheet which does not contain the detected element such that the first printing sheet is selected for at least one page; a supplier that supplies the first or the second printing sheet selected by the selector; a printer that sequentially prints the document acquired by the acquiring unit on the printing sheets supplied by the supplier; a detector that detects a detected element contained in a printing sheet on which the document is printed by the printer; and a reporter that reports detection of the detected element in a printing sheet by the detector. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiments of the present invention will be described in detail based on the following figures, wherein: 
         FIG. 1  shows the configuration of an information management system according to an aspect of the invention; 
         FIG. 2  is block diagram that shows the configuration of a printer according to an aspect of the invention; 
         FIG. 3  is a block diagram that shows the configuration of a gate apparatus according to an aspect of the invention, and 
         FIG. 4  is a flowchart that shows an operation of the printer. 
     
    
    
     DETAILED DESCRIPTION 
     Configuration of Exemplary Embodiment 
       FIG. 1  shows the configuration of an information management system  100  according to one exemplary embodiment of the invention. The information management system  100  is, for example, a system constructed in an environment where documents are output (created) such as an office. As shown in  FIG. 1 , the information management system  100  is provided with multiple printers  10 , multiple gate apparatuses  20 , a network  30 , and an administrator terminal  40 . 
     Also, the environment where the information management system  100  is constructed includes multiple areas with different security levels. In this exemplary embodiment, it is assumed that there is an “area A” with a comparatively high security level and an “area B” with a comparatively low security level. In area A, documents with a comparatively high level of importance are output, and in area B, documents with a comparatively low level of importance are output. Also, although not particularly shown in  FIG. 1 , there is a user terminal such as a personal computer operated by a user in each area, and the user uses this user terminal to instruct a printer  10  to output a document. 
     Also note that the number of areas can be set as desired, and there may be three or more security levels for an area. 
     The printer  10  is an apparatus that records (i.e., prints) text or images to paper according to an instruction from a user. The recording system of the printer  10  is not particularly limited, and for example is an electrophotographic system, an inkjet system, or the like. At least one printer  10  is provided in each area. When multiple printers  10  are provided in a particular area, the security level may vary between the printers  10 . For the sake of convenience, here a case will be described in which one printer  10  is provided in each area. 
     There are two types of paper used in the printers  10 , “special paper” and “regular paper”. In this exemplary embodiment, special paper is paper that includes a detected element, and regular paper is paper that does not include this detected element. Here, a detected element refers to an object that can be detected by a gate apparatus  20 . As a detected element, it is possible to adopt, for example, a wire or foil body in which a large Barkhausen effect or magneto-strictive vibration occur, an RFID (Radio Frequency Identification) tag, or the like. It is desirable that the detected element is included by being embedded into the paper in order that the detected element is not easily recognized from external appearance. 
       FIG. 2  is a block diagram that shows the configuration of a printer  10 . As shown in  FIG. 2 , the printer  10  is provided with a controller  11 , a communications unit  12 , a paper supply unit  13 , a printing unit  14 , and a post-processing unit  15 . The controller  11  is provided with a CPU (Central Processing Unit), a memory, and the like, and controls operation of each unit of the printer  10 . The communications unit  12  is an interface for communicating with the network  30  or a user terminal, and receives document data or policy information described below and supplies the received document data or policy information to the controller  11 . The paper supply unit  13  is provided with a first tray  131  and a second tray  132 , and supplies paper that has been stored in these trays in response to an instruction from the controller  11 . Special paper is stored in the first tray  131  and regular paper is stored in the second tray  132 . 
     In the printing unit  14 , a document expressed by document data acquired via the controller  11  is printed on paper that has been supplied from the paper supply unit  13 , and the printed paper is supplied to the post-processing unit  15 . Here, document data is data that expresses a document that includes text or images, and that data corresponds to multiple pages of paper. The post-processing unit  15  performs processing (referred to below as “post-processing”) that binds the paper corresponding to the multiple pages of paper on which text or images have been printed such that the paper becomes a single booklet. The post-processing unit  15  may bind paper with staples, or may bind paper with an adhesive. For convenience of description, in the present exemplary embodiment, a booklet that has been bound by the post-processing unit  15  is also referred to as a “document”. That is, in this exemplary embodiment, “document” refers both to text or images expressed by document data, and a bound booklet in which these have been printed. 
       FIG. 3  is a block diagram that shows the configuration of the gate apparatus  20 . As shown in  FIG. 3 , the gate apparatus  20  is provided with a detection unit  21 , a send unit  22 , and a warning unit  23 . The detection unit  21  detects whether or not a detected element is present in a predetermined range. When the detection unit  21  detects a detected element, information expressing the presence of a detected element (referred to below as “detection information”) is supplied to the send unit  22  and the warning unit  23 . Of the detection unit  21 , the concrete configuration and the detection range in which the detected element can be detected vary according to the type of detected element. The send unit  22  is an interface that connects to the network  30  and sends the detection information to the administrator terminal  40 . The warning unit  23  is provided with a so-called revolving light, a speaker, and the like, and emits light and sound when acquiring detection information. 
     The gate apparatus  20  is provided at the border (for example, such as an entrance/exit) of each area, and detects that a document including a detected element has passed by. In the gate apparatus  20 , when a document including a detected element has been detected, the gate apparatus  20  reports via the send unit  22  and the warning unit  23  that a document has been taken out. Also, in  FIG. 1 , there is only one gate apparatus  20 , but when there are multiple borders of each area, it is desirable that multiple gate apparatuses  20  are provided. 
     The detection range in which the gate apparatus  20  can detect a detected element may change according to the manner in which a document is taken out. For example, in a case in which a user attempts to take out a document after inserting the document into a briefcase or bag, the detectable range is less than for a case in which the document is taken out as-is, and as a result there is a possibility that detection will fail. 
     Here, returning to the description of  FIG. 1 , the network  30  is for example a LAN (Local Area Network), and connects the printers  10 , the gate apparatuses  20 , the administrator terminal  40 , and the user terminal to each other. The administrator terminal  40  is a computer used by an administrator of the mentioned system, and supplies policy information to the printers  10 . Also, the administrator terminal  40  is provided with a monitor that monitors the detection information, and is configured so as to be capable of notifying the administrator of whether or not taking out of a document has occurred in each area. 
     Also, although not particularly shown in  FIG. 1 , the information management system  100  may also be provided with a camera that monitors entrance and exit of people at the border of each area. By doing so, it becomes possible to record video at the same time as detection by a gate apparatus  20 , and also possible to identify a person. 
     The policy information expresses a security level, and indicates to what extent to include special paper when printing a document. In this exemplary embodiment, the policy information is a value that indicates that the security level is either “high” or “low”. However, the policy information may also indicate multiple grades of the security level. 
     Operation in Exemplary Embodiment 
     The configuration of the information management system  100  is as follows. In the thus-configured information management system  100 , the user uses a user terminal to instruct output of a document and a printer  10  outputs the document. When detecting that a document including a detected element has been taken out, the gate apparatus  20  reports this event. By operating in the above manner, the information management system  100  is capable of suppressing unauthorized taking out of a document. 
     When a printer  10  outputs a document, it acquires policy information from the administrator terminal  40 , and controls the manner of printing the document according to the policy information. More specifically, the printer  10  performs printing while selecting, based on the policy information, whether the paper used for each page of the document is special paper or regular paper. The operation performed by the printer  10  in this case is as follows. 
       FIG. 4  is a flowchart that shows the operation of the printer  10 . As shown in  FIG. 4 , first, the controller  11  of the printer  10  acquires policy information (Step S 1 ). The controller  11  may acquire the policy information either by making a request to the administrator terminal  40  for sending of the policy information, or by reading out that policy information which was sent by the administrator terminal  40  at a predetermined timing and stored in a memory. Next, the controller  11  acquires document data from the user terminal (Step S 2 ). 
     Next, the controller  11  designates a total number (n) of printing sheets of paper to be used, based on the acquired document data (Step S 3 ). Here, the value of n is designated from the number of pages of the document expressed by the document data. Specifically, if the number of pages is 10 pages, the value of n is “10”. 
     Also, the controller  11  designates a number of sheets (k) of special paper among the paper to be used, based on the acquired policy information and the total number of sheets of paper (n)(Step S 4 ), and further designates pages for which special paper will be used (Step S 5 ). The ratio of special paper is determined so as to be higher in a case in which the security level indicated by the policy information is “high”, and lower in a case in which the security level indicated by the policy information is “low”. For example, the ratio of special paper may be determined such that when the security level is “high”, 70% of the total number of sheets of paper is special paper, and when the security level is “low”, 30% of the total number of sheets of paper is special paper. When, for example, the total number of sheets of paper is low, the ratio of special paper may be determined such that the number of sheets of special paper is greater than a predetermined ratio. For example, when the security level is “low”, i.e. when 30% of the total number of sheets of paper is special paper, and the total number of sheets of paper is “5”, because the number of sheets of special paper is not evenly divisible using the predetermined ratio (30%), the ratio of special paper may be set to two sheets (40%). 
     Also, the controller  11 , in Step S 5 , appropriately selects the pages for which special paper will be used from among the total number of sheets of paper. For example, when the total number of sheets of paper is “10”, and 70% of the total number of sheets of paper is set as special paper, the controller  11  may use special paper for pages 1 to 7, and use regular paper for pages 8 to 10. Alternatively, special paper and regular paper may be used in a pattern that satisfies a predetermined ratio, such that special paper us used for pages 1 and 2, regular paper is used for page 3, and special paper is used for pages 4 and 5. However, when special paper and regular paper have been used in a regulated manner, the user can guess which pages the special paper is used for. Therefore, it is more preferable that pages for which special paper will be used are selected in a random order, using random numbers or the like. In the above manner, of the total pages n, pages i( 1 ), i( 2 ), . . . , i(k) that will be printed using special paper are assigned. 
     After the pages for which special paper will be used are designated, the controller  11  instructs the paper supply unit  13  to supply paper in order beginning from the first page (Step S 6 ). The value of a page for which supply is instructed here is referred to below as “i”. More specifically, the value of i is an integer from 1 to n. The default value of i is “1”. 
     At this time, when page i is selected as a page for which special paper will be used, i.e., when i is any of i( 1 ), i( 2 ), . . . , i(k), the controller  11  instructs to supply special paper, and when this is not the case, the controller  11  instructs to supply regular paper. In response to this instruction, the paper supply unit  13  supplies paper from either the first tray  131  (special paper) or the second tray  132  (regular paper). 
     Next, the controller  11  instructs the printing unit  14  to print page i of the document on the paper supplied by the paper supply unit  13  (Step S 7 ). In response to this instruction, the printing unit  14  prints page i of the document on the supplied paper. 
     After printing of page i by the printing unit  14  ends, the controller  11  judges whether or not printing of all pages of the document has ended. That is, the controller  11  judges whether or not the value of i is n (Step S 8 ). Here, when the value of i is not n (NO in Step S 8 ), the controller  11  increases (increments) the value of i (Step S 9 ), and again executes the processing of Step  6  and subsequent steps. For example, when the value of i is “1”, the controller  11  increases this value by one page to “2”, and instructs supply of paper and printing of the page 2. 
     On the other hand, when the value of i is n (YES in Step S 8 ), the controller  11  judges that printing of all pages of the document expressed by the document data has ended. Then, the controller  11  instructs the post-processing unit  15  to execute post-processing (Step S 10 ). In response to this instruction, the post-processing unit  15  binds all of the supplied paper for all pages into a single booklet. 
     The operation of the printer  10  is as follows. By performing this sort of operation, the printer  10  of this exemplary embodiment is capable of determining the ratio of special paper and regular paper based on policy information. Accordingly, with this printer  10 , it is possible to set different security levels for each area where the printer  10  is installed, or to change the security level according to an instruction from the administrator terminal  40 . Also, for example, the printer  10  may be programmed to automatically raise the security level when warnings frequently occur, without judgment of the administrator. 
     MODIFIED EXAMPLES 
     The invention can be carried out in a mode different from the embodiment described above. For example, the invention can be carried out in a mode as described below. Also, each of the modified examples disclosed below may be combined as appropriate. 
     (1) Modified Example 1 
     In the invention, when selecting a special paper (we call it “first sheet”, hereafter) or a regular paper (we call it “second sheet”, hereafter), this selection may be made not according to the policy information. For example, a user may designate either sheet for each page using an operating unit such as a button or a touch panel, or the first sheet and the second sheet may be selected alternately in advance. 
     Of course, there may also be a case in which a document is printed without including any first sheets, or a case in which a document is printed without including any second sheets. 
     (2) Modified Example 2 
     Multiple pieces of information that correspond to the “policy information” described above may be stored in advance in a printing apparatus (printer  10 ). In this case, for example, the user may designate a security level using an operating unit such as a button or a touch panel, or the security level may vary according to a time span. In the latter example, for example, the security level may be relatively low during working hours (i.e., a state in which viewing by many third parties is possible), and relatively high outside of working hours. In this case, a unit that judges the time span is provided in the printing apparatus. 
     (3) Modified Example 3 
     Information that corresponds to the “policy information” described above may be acquired along with document data, or may be included in the document data itself. For example, the document data may, as so-called header information or metadata, accompany information that corresponds to policy information. In such a case, because the security level can be changed for each piece of document data, for example, it is possible to perform printing such that a document with a high level of importance includes more first sheets (special paper), and a document with a low level of importance includes more second sheets (regular paper). 
     (4) Modified Example 4 
     In the invention, it is possible to perform exceptional processing according to the number of pages even when sheet selection is performed according to policy information. For example, when the number of pages is too small, first sheets (special paper) may be used for all pages regardless of the policy information, and when the number of pages is too large, first sheets may be not used above an upper limit for the number of first sheets. 
     In this example, a description is given in which p represents a detection ratio per one first sheet, P represents a detection ratio of a booklet (detection ratio when a whole booklet was taken out), and N represents the number of first sheets included in the booklet. In this case, the booklet detection ratio P can be expressed with equation (1) below. Below, the detection ratio p is assumed to be 50% (0.5). 
     (Equation 1)
 
 P= 1−(1 −p ) N   (1)
 
     For example, when the number of first sheets N is “1”, the booklet detection ratio P is “50%”. When the number of first sheets N is “2”, the booklet detection ratio P is “75%”. In this manner, the booklet detection ratio P becomes closer to “1”, as the value of N increases. For example, when the detection ratio p is assumed to be 50%, if the value of N is “7” then the booklet detection ratio P exceeds “99%” and thereafter becomes about 100%. 
     In other words, whatever the value of the detection ratio p may be, the value of the booklet detection ratio P converges at “1” according to the increase in the value N. Therefore, for example, in a case in which 10 first sheets are included in a 100 page booklet, or in a case in which 50 first sheets are included, there is approximately no difference in the booklet detection ratio P. Accordingly, from the viewpoint of cost effectiveness, it is desirable that a predetermined value is set as an upper limit for the number of first sheets N, and above that limit first sheets are not used. The upper limit of N may be appropriately determined according to the detection ratio P allowed in the system, or the actual detection ratio p. 
     Also, depending on the type of special paper, there may be a case in which in the manufacturing process of that special paper there is sheet-to-sheet variation in the detection ratio p, and special paper having a low detection ratio p is deemed to be a defective good and therefore not used, but even this sort of special paper can be used without problem when the number of pages in a booklet is high. 
     On the other hand, when the number of pages in a booklet is too small, there may be instances when the booklet cannot be detected well even if first sheets are used according to the predetermined ratio. For example, when the number of pages in a booklet is “3”, and of these a first sheet is used for one page, if the detection ratio p is 50%, the booklet detection ratio P also is limited to “50%”. Therefore, in such a case, for example, first sheets may be used for all pages, so that the number first sheets used is greater than the predetermined ratio. 
     (5) Modified Example 5 
     The pages for which first sheets (regular paper) will be used may be selected according to a printing ratio or text ratio of each page. For example, with respect to a page in which more text or images are printed, there is a high possibility that more information is included than in other pages, and also a high possibility that important information is included. Therefore, with respect to such a page, there is a (comparatively) high possibility that a problem will occur when the page is extracted from a booklet and individually taken out. On the other hand, with respect to a blank page or a page in which there is almost no printing, there is a high possibility that almost no problem will occur even if that page is individually taken out. 
     Therefore, if a configuration is adopted in which the printing apparatus (printer  10 ) is provided with a unit that calculates the printing ratio (or number of characters) of each page of the document expressed by the document data, and a first sheet is preferentially selected for a page with a high printing ratio (or a large number of characters), it is possible to further suppress leakage of information. Here, “printing ratio” refers to, for example, a ratio of a region where printing is performed to a region where printing can be performed on a sheet. That is, more text or images or included in a page with a higher printing ratio. 
     (6) Modified Example 6 
     For example, when the pages for which first sheets (special paper) will be used are selected in a random order, the sheets to be supplied (i.e. trays) are frequently switched. When this sort of sheet switching is frequently performed, there is the problem of an increase in the time needed until document printing is completed. 
     Thus, in such a case, the sequence for printing each page may be changed so as to reduce the number of times for sheet switching. Specifically, a sequence may be adopted such that after designating the pages for which special paper (first sheets) will be used in Step  5  described above, printing of the pages designated here is performed first, and then printing of the other pages for which regular paper (second sheets) will be used is performed. For example, for a 5 page document, when special paper is used for pages 1, 3, and 5, and regular paper is used for pages 2 and 4, the printing of pages 1, 3, and 5 is collectively performed first, and the printing of pages 2 and 4 is performed afterward. Of course, a sequence may also be adopted such that printing of pages for which regular paper will be used is performed first, and printing of pages for which special paper will be used is performed afterward. 
     When printing is performed in a sequence that differs from the page sequence in this manner, the sequence in which paper is supplied to the post-processing unit  15  differs from the page sequence, so there happens the problem that if the pages are bound in a booklet as-is, the pages will not be arranged in the correct page order. Thus, in this sort of case, it is desirable that the post-processing unit  15  is further provided with a unit that changes the arrangement of paper, and the arrangement of paper is switched such that the paper is arranged in the page order. 
     (7) Modified Example 7 
     In the invention, there may be instances in which first sheets (special paper) and second sheets (regular paper) can be easily recognized, depending on the type of the detected element. In this sort of case, when all first sheet is extracted from a booklet, there is a risk that it will not be possible to detect unauthorized taking out. Thus, in order to make recognition (or distinguishment) of first sheets and second sheets difficult, a dummy image that simulates the detected element may be printed on second sheets. 
     (8) Modified Example 8 
     In the invention, the manner of acquiring document data is not particularly limited to that mentioned above. Document data can be acquired from various interfaces, whether wired or wireless. For example, document data may be acquired via an image capturing apparatus (scanner), in the manner of a so-called copy machine, or document data may be acquired from a removable storage medium. 
     (9) Modified Example 9 
     In the invention, “sheet” encompasses various types of paper. In the invention “sheet” encompasses not only so-called paper, but all sheet-like objects on which printing is possible. For example, in the invention, a “sheet” may be a sheet-like resin. 
     Also, in the invention, a “detected element” may be included in a sheet in any manner. In the embodiments described above, the detected element is embedded into the paper, but for example, the detected element may be bonded to the surface of the paper, or the detected element may be integrated with the paper in another manner. 
     (10) Modified Example 10 
     The invention can also be provided as a program for realizing the functions of the printing apparatus described above. This program may, for example, be downloaded to a printing apparatus via a network such as the Internet, or may be provided in a form stored on a recording medium such as an optical disk. 
     The foregoing description of the embodiments of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, thereby enabling others skilled in the art to understand the invention for various embodiments and with the various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents.