Abstract:
An image forming apparatus that includes: a memory that stores image data associated with authentication information; an authentication unit that compares authentication information received through a receiving unit with the authentication information associated with the image data, and performs authentication; an image forming unit that forms an image from the image data stored in the memory, when the authentication is successful; a detector that determines whether an operator is within a detection range; and a controller that controls the image forming unit to stop image formation, when the detector determines that the operator is not within the detection range.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2006-231216 filed Aug. 28, 2006. 
       BACKGROUND 
       [0002]    1. Technical Field 
         [0003]    The present invention relates to an image forming apparatus, an image forming system, a computer readable medium storing a program, and a method. 
         [0004]    2. Relate Art 
         [0005]    In recent years, there have been many systems in which complex machines including printers or printer functions and client apparatuses that output print requests are connected to a network, so that two or more printers can be shared between two or more client apparatuses. 
       SUMMARY 
       [0006]    According to an aspect of the invention, there is provided an image forming apparatus that includes: a memory that stores image data associated with authentication information; an authentication unit that compares authentication information received through a receiving unit with the authentication information associated with the image data, and performs authentication; an image forming unit that forms an image from the image data stored in the memory, when the authentication is successful; a detector that determines whether an operator is within a detection range; and a controller that controls the image forming unit to stop image formation, when the detector determines that the operator is not within the detection range. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    Exemplary embodiments of the present invention will be described in detail based on the following figures, wherein: 
           [0008]      FIG. 1  is a block diagram showing a system structure in accordance with a first exemplary embodiment of the present invention; 
           [0009]      FIG. 2  shows an example of the display screen of the printer driver; 
           [0010]      FIG. 3  shows the structure of the operation/display unit of each printing apparatus; 
           [0011]      FIG. 4  is a block diagram showing the structure of the controller of each printing apparatus; 
           [0012]      FIG. 5  is a flowchart showing the procedures to be carried out in a client terminal to generate print data and transmit the print data to a printing apparatus; 
           [0013]      FIG. 6  is a flowchart showing the procedures to be carried out in a printing apparatus that receives print data set for confidential printing in accordance with the first exemplary embodiment; 
           [0014]      FIG. 7  is a block diagram showing a system structure in accordance with a second exemplary embodiment of the present invention; 
           [0015]      FIG. 8  is a flowchart showing the procedures to be carried out in a printing apparatus that receives print data set for confidential printing in accordance with the second exemplary embodiment; 
           [0016]      FIG. 9  is a flowchart showing the procedures to be carried out in a printing apparatus that receives print data set for confidential printing in accordance with a third exemplary embodiment of the present invention; 
           [0017]      FIG. 10  is a flowchart showing the procedures to be carried out in a printing apparatus that receives print data set for confidential printing in accordance with a fourth exemplary embodiment of the present invention; 
           [0018]      FIG. 11  is a flowchart showing the procedures to be carried out in a printing apparatus that receives print data set for confidential printing in accordance with a fifth exemplary embodiment of the present invention; and 
           [0019]      FIG. 12  is a flowchart showing the procedures to be carried out in a printing apparatus that receives print data set for confidential printing in accordance with a sixth exemplary embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]    The following is a description of exemplary embodiments of the present invention, with reference to the accompanying drawings. 
       First Exemplary Embodiment  
       [0021]    Referring first to  FIG. 1 , a system structure of this exemplary embodiment is described. In this exemplary embodiment, client terminals  10 A and  10 B and printing apparatuses  20 A and  20 B are connected via a network  30 , so that bidirectional communication can be performed between the client terminals  10 A and  10 B and the printing apparatuses  20 A and  20 B. In the system structure shown in  FIG. 1 , the two client terminals  10 A and  10 B and the two printing apparatuses  20 A and  20 B are connected to the network  30 . However, the number of apparatuses is not limited to two, and one apparatus, or three or more apparatuses may be connected to the network. Also, the number of client devices connected to the network  30  may not be equal to the number of printing apparatuses connected to the network  30 . 
         [0022]    The network  30  may be a LAN (Local Area Network) using lines such as cable lines or not using such lines, a WAN (Wide Area Network), the Intranet, or the Internet. In some cases, the network  30  may be formed with public lines or printer cables. 
         [0023]    The structure of the client terminal  10 A is now described. Since the client terminal  10 B has the same structure as the client terminal  10 A, explanation of the client terminal  10 B is omitted here. The client terminal  10 A may be a personal computer, for example, and includes a communication interface unit  11 , a controller  12 , a data memory  13 , and an operation/display unit  14 . The communication interface unit  11  is the interface for bidirectional communication (information exchange) with the printing apparatuses  20 A and  20 B via the network  30 . The control program to be used by the controller  12 , information as to the data printing history, and the likes, are stored in the data memory  13 . The operation/display unit  14  is the device to be operated by users to input various settings to the client terminal  10 A, so as to instruct a printing operation, cancel a printing operation, and check a printing state. The operation/display unit  14  also serves as the display that notifies the operator of the operation result. 
         [0024]    The controller  12  reads the control program stored in the data memory  13 , and performs an operation in accordance with the control program. By doing so, the controller  12  executes various application programs to produce data such as a document, a figure, and an image, or functions as a printer driver to be used for printing the produced data. 
         [0025]    The printer driver processes the data to be printed out, and has a data generating function to generate print data in the PDL (page description language) format and an information adding function to add predetermined information to the print data generated by the data generating function, for example. In a case where a confidential printing operation is performed with the use of the printing system, the additional information to be added by the information adding function includes attribute information indicating that the printing operation is a confidential printing operation, and authentication information (such as user identification information and a password) required for the confidential printing operation. At the time of setting for data printing, the printer driver causes the operation/display unit  14  to display the display screen shown in  FIG. 2 , and prompts the user to input settings such as the user identification information and a password. The input authentication information is added to the print data in the PDL format as data in the PJL (printer job language) format, for example. The PJL format is also used as the data format when various settings and changes are made by sending command information from the client terminals  10 A and  10 B to the printing apparatuses  20 A and  20 B. 
         [0026]    Each printing apparatus  20  receives print data transmitted from the client terminal  10 A or  10 B via the network  30 , and prints out the received print data on a recording medium such as a paper sheet. The printing apparatus  20  operates not only in a regular printing mode in which print data received from the client terminals  10 A and  10 B via the network  30  is not stored and is printed out right away, but also in a confidential printing mode in which print data received from the client terminals  10 A and  10 B via the network  30  is stored temporarily in the data memory, and previously stored print data is printed out after user authentication using the operation unit of the apparatus. 
         [0027]    Confidential printing is a printing operation in which an operator operates the printing apparatus  20 A or  20 B so that the printout (a paper document) of the print data the operator sent from the client terminal  10 A or  10 B to the printing apparatus  20 A or  20 B cannot be seen by others. 
         [0028]    Referring back to  FIG. 1 , the structure of the printing apparatus  20 A is described. Since the printing apparatus  20 B has the same structure as the printing apparatus  20 A, explanation of the printing apparatus  20 B is omitted here. As shown in  FIG. 1 , the printing apparatus  20 A includes a communication interface unit  21 , an operation/display unit  22 , a controller (serving as the authentication unit and the controller of the present invention)  23 , an image processor  24 , a data memory  25 , a printer  26 , and an operator detecting sensor  27 . 
         [0029]    The communication interface unit  21  is the interface for bidirectional communication (information exchange) with the client terminals  10 A and  10 B via the network  30 . The various kinds of information (such as print data) transmitted from the client terminals  10 A and  10 B are received by the communication interface unit  21  via the network  30 , and are then transferred to the controller  23 . 
         [0030]    The operation/display unit  22  is the user interface for inputting operations, and includes an operation unit  60  and a display  61 . The display may be a liquid crystal display or a CRT, for example. The operation unit  60  may be formed with a general-purpose keyboard or a specially designed operation panel, for example.  FIG. 3  shows an example of the operation/display unit  22 . A numeric keypad, a start button, FAX-, print-, and copy-start buttons, a power off button, an error display button, and the likes, are provided on the operation unit  60 . LEDs (Light Emitting Diodes) are turned on and off, to indicate that each button is selected or not selected. 
         [0031]    The controller  23  analyzes information that is received from the client terminal  10 A or  10 B. Based on the analysis result, the controller  23  transfers the information to some other function unit. If the analyzed information contains print data, the controller  23  transfers the print data to the image processor  24 , which then converts the print data into image data that can be printed by the printer  26 . 
         [0032]    When receiving print data that is transmitted as confidential print data (containing additional information including attribute information that indicates the printing operation to be performed is a confidential printing operation, and authentication information such as user identification information and a password) from the client terminal  10 A or  10 B, the controller  23  stores the print data and the additional information added to the print data temporarily in the data memory  25 . When a print request to print out print data set for confidential printing is input by an operator through the operation/display unit  22 , the controller  23  causes the display  61  to display an input request screen for authentication information, and prompts the operator to input the authentication information, as shown in  FIG. 3 . After the authentication information is input, the controller  23  compares the input authentication information with the authentication information added as the additional information to the print data, to determine whether they match. If the input authentication information matches the authentication information added to the print data, the controller  23  causes the image processor  24  to convert the print data stored in the data memory  25  into image data, and to output the image data to the printer  26 . The printer  26  then performs printing. 
         [0033]    The input of the authentication information may be performed by a key operation on the operation/display unit  22 , or may be performed by reading the authentication information recorded on a portable recording medium (such as an IC card) owned by the operator, when the recording medium is inserted in a slot. Other than that, biological information (such as a finger print) indicating a physical feature of the operator may be used as the authentication information, and the authentication information may be input by detecting the biological information with a sensor (such as a fingerprint sensor). 
         [0034]    The controller  23  also receives a detection signal that is output when the operator detecting sensor  27  detects the operator, and then determines whether printing of the print data should be allowed. When the detection signal is not input from the operator detecting sensor  27 , the controller  23  determines that there is not the operator near the printing apparatus  20 A, and stops the printing of the print data set as a confidential printing operation. When a printing operation is aborted, the controller  23  stores the information as to the page(s) on which the printing of the print data has already been completed in a RAM  43  or a NVRAM (Non-Volatile RAM)  44 . In the next printing operation, the information as to the printed page(s) is referred to, so that printing can be resumed from the page next to the last page printing has been completed. 
         [0035]    The operator detecting sensor  27  is the sensor for detecting an operation. For example, when detecting the operator near the printing apparatus  20 , the operator detecting sensor  27  outputs a detection signal to the controller  23 . Although a sensor is employed to detect an operator in this exemplary embodiment, other various methods may be utilized. For example, a camera may be employed to take a picture of the operator, or wireless communication may be performed with an IC tag owned by the operator, so as to detect the operator. 
         [0036]      FIG. 4  shows the structure of the controller  23 . The controller  23  includes a CPU  41 , a ROM  42 , the RAM  43 , the NVRAM  44 , and an I/O port  45 . The CPU  41  reads a program stored in the ROM  42 , and performs an operation in accordance with the program, to control printing through the procedures shown in a flowchart described later. Operation result data and the printed page information are written in the RAM  43 . The data that is written in the RAM  43  and needs to be backed up when the power is turned off is stored in the NVRAM  44 . 
         [0037]    The program stored in the ROM  42  may be read from a recording medium such as a CD-ROM and then stored in the NVRAM  44 , or may be received by the communication interface unit  11  via a network and then stored in the NVRAM  44 . 
         [0038]    The data memory  25  stores print data for confidential printing and various kinds of information for the confidential printing. The data memory  25  may be a hard disk or a nonvolatile memory (such as an EEPROM). 
         [0039]    The printer  26  performs a printing operation based on the print data (image data) transmitted from the controller  23 , and prints out an image on a recording medium such as a paper sheet. 
         [0040]    Referring now to the flowchart shown in  FIG. 5 , the procedures to be carried out to generate print data in the client terminal  10 A are described. In the client terminal  10 B, print data and a print request are generated in the same manner as described below. 
         [0041]    In the client terminal  10 A, print data is first created in accordance with an installed application program, and a print instruction is issued (step S 1 ). However, it is not necessary to create print data each time, and it is of course possible to instruct to print out print data already created and stored. 
         [0042]    When a print instruction is issued from the application program (“YES” in step S 1 ), the printer driver installed in the client terminal  10 A processes the print data to be printed out, and generates print data in the PDL format. In a case where the generated print data is to be printed out in a confidential printing operation (“YES” in step S 2 ), the printer driver causes the operation/display unit  14  to display the screen shown in  FIG. 2 , and requests an input of authentication information (such as user identification information and a password) required for authentication (step S 4 ). 
         [0043]    When authentication data is input (“YES” in step S 4 ), the printer driver adds the attribute information indicating the printing is confidential printing, and the authentication information (such as user identification information and a password) required for the printing information, as the additional information to the print data, and transmits the print data and the additional information to the printing apparatus  20 A or  20 B (step S 5 ). The additional information is added to the print data in the PDL format as data in the PJL format, for example. 
         [0044]    If the printing operation to be performed is not a confidential printing operation (“NO” in step S 2 ), the controller  12  transmits the print data to the printing apparatus  20 A or  20 B (step S 3 ). 
         [0045]    Referring now to the flowchart shown in  FIG. 6 , an operation to be performed in the printing apparatus  20 A that receives print data is described. The same operation as this is also performed in the printing apparatus  20 B. 
         [0046]    The controller  23  of the printing apparatus  20 A stands by for print data from the client terminal  10 A (step S 11 ). When receiving print data (“YES” in step S 11 ), the controller  23  analyzes the additional information added to the received print data, and determines whether the print data is set for confidential printing (step S 12 ). If the print data is not set for confidential printing (“NO” in step S 12 ), the controller  23  causes the image processor  24  to convert the received print data into image data, and transfers the image data to the printer  26  to perform a regular printing operation (step S 21 ). 
         [0047]    If the print data is set for confidential printing (“YES” in step S 12 ), the controller  23  stores the received print data temporarily in the data memory  25 . The controller  23  does not print the print data stored in the data memory  25  as it is, but causes the display  61  to display a request for an input of authentication information on the display screen (step S 13 ) The controller  23  then stands by until an operator inputs authentication information. 
         [0048]    In a case where no authentication information is input by an operator over an allowed period of time (“NO” in step S 14 , and “YES” in step S 15 ), this operation comes to an end. In a case where authentication information is input by an operator within the allowed time (“YES” in step S 14 ), the controller  23  compares the input authentication information with the authentication information added as the additional information (step S 16 ), to determine whether the operator is an authorized user who is allowed to makes copies. 
         [0049]    In a case where the input authentication information does not match the authentication information added as the additional information (“NO” in step S 16 ), the controller  23  determines whether the number of authentication failures is within an allowed number (step S 17 ). If the number of authentication failures is within the allowed number (“YES” in step S 17 ), the controller  23  causes the display  61  to display a message to the effect that the authentication has failed, and again requests for an input of authentication information (step S 13 ). If the number of authentication failures exceeds the allowed number (“NO” in step S 17 ), the controller  23  ends this operation. 
         [0050]    In a case where the input authentication information matches the authentication information added as the additional information (“YES” in step S 16 ), the controller  23  determines whether the operator detecting sensor  27  has successfully detected the operator (step S 18 ). In a case where the operator detecting sensor  27  fails to detect the operator (“NO” in step S 18 ), the controller  23  ends the operation, and stores the information as to the page(s) on which the printing of the print data has been completed (the printed page information) in a memory such as the RAM  43  (step S 19 ). In a case where the printing has not been completed on even one page, “0” is recorded as the printed page number. In a case where the operator detecting sensor  27  has successfully detected the operator (“YES” in step S 18 ), the controller  23  reads one page of the print data stored in the data memory  25 , and causes the image processor  24  to convert the read print data into image data. The controller  23  then outputs the image data to the printer  26  to perform the printing of the one page (step S 20 ). After the printing of the one page is completed, the controller  23  determines whether all the print data has been printed out (step S 22 ). In a case where the printing of all the print data has not been completed (“NO” in step S 22 ), the controller  23  again determines whether the operator detecting sensor  27  has successfully detected the operator (step S 18 ). In a case where the operator detecting sensor  27  has successfully detected the operator (“YES” in step S 18 ), the controller  23  performs the printing of the next one page (step S 20 ). When the operator detecting sensor  27  fails to detect the operator (“NO” in step S 18 ), the controller  23  ends the operation, and stores the printed page information in the data memory  25  (step S 19 ). Those procedures are repeated. When the printing of all the print data has been completed (“YES” in step S 22 ), this operation comes to an end. 
       Second Exemplary Embodiment  
       [0051]    The following is a description of a second exemplary embodiment of the present invention, with reference to the accompanying drawings. In the above-described first exemplary embodiment, the operator detecting sensor  27  is mounted on each of the printing apparatuses  20 A and  20 B, so as to determine whether the operator is near the printing apparatus  20 A or  20 B. 
         [0052]    In this exemplary embodiment, a specially designed device is not provided, and an operator near the printing apparatus  20 A or  20 B is detected by determining whether a certain key of the operation unit  60  is pressed down. In a case where the certain key of the operation unit  60  keeps pressed down, the controller  23  allows the printing of the print data. The certain key may be any key of the operation unit  60 . In a case where the display  61  is a touch-panel display having a display screen such as a LCD (Liquid Crystal Display) integrated with a touch panel, the certain key may be displayed on the display  61 , and the touch panel detects the key.  FIG. 7  shows the structure of the printing apparatus  20 A of this exemplary embodiment. 
         [0053]    Referring now to the flowchart shown in  FIG. 8 , an operation in accordance with this exemplary embodiment is described. Since the procedures from an input of authentication information till authentication are the same as those of the first exemplary embodiment, explanation of them is omitted here. 
         [0054]    The controller  23  compares the authentication information input through the operation unit  60  with the authentication information extracted from the additional information, to determine whether they match (step S 36 ). If the input authentication information matches the extracted authentication information (“YES” in step S 36 ), the controller  23  determines whether the certain key of the operation unit  60  is pressed down (step S 38 ). If the certain key is pressed down (“YES” in step S 38 ), the controller  23  reads one page of the print data stored in the data memory  25 , and causes the image processor  24  to convert the read print data into image data. The controller  23  then outputs the image data to the printer  26  to perform printing (step S 40 ). After the printing of the one page is finished, the controller  23  determines whether all the print data has been printed out (step S 42 ). In a case where the printing of all the print data has not been completed (“NO” in step S 42 ), the controller  23  determines whether the certain key has kept pressed down (step S 38 ). In a case where the certain key has kept pressed down (“YES” in step S 38 ), the controller  23  performs the printing of the next one page (step S 40 ). In this manner, while the certain key of the operation unit  60  keeps pressed down, the print data is read from the data memory  25 , and printing is performed. When the certain key of the operation unit  60  stops being pressed down (“NO” in step S 38 ), the controller  23  ends the operation, and stores the printed page information in the data memory  25  (step S 39 ) 
       Third Exemplary Embodiment  
       [0055]    The following is a description of a third exemplary embodiment of the present invention, with reference to the accompanying drawings. Since the structure of this exemplary embodiment is the same as the structure of the above-described second exemplary embodiment, explanation of it is omitted here. 
         [0056]    In the second exemplary embodiment, printing of print data is performed while a certain key keeps pressed down. In this exemplary embodiment, an operator is requested to make a key input for each one page. Referring now to the flowchart shown in  FIG. 9 , an operation in accordance with this exemplary embodiment is described. Since the procedures from an input of authentication information till authentication in this exemplary embodiment are the same as those of the first exemplary embodiment, explanation of them is omitted here. 
         [0057]    The controller  23  compares the authentication information input through the operation unit  60  with the authentication information extracted from the additional information, to determine whether they match (step S 56 ). If the input authentication information matches the extracted authentication information (“YES” in step S 56 ), the controller  23  causes the display  61  to display a screen for requesting the operator to press the certain key of the operation unit  60  (step S 58 ). In a case where the certain key has not been pressed during a predetermined input waiting time since the request to press the certain key (“NO” in step S 59 , and “NO” in step S 60 ), the controller  23  ends the operation, and stores “0” as the printed page number in a memory such as the RAM  43 . If the certain key is pressed within the input waiting time (“YES” in step S 59 ), the controller  23  reads one page of the print data stored in the data memory  25 , and causes the image processor  24  to convert the read print data into image data. The controller  23  then outputs the image data to the printer  26  to perform printing (step S 62 ). After the printing of the one page is finished, the controller  23  determines whether all the print data has been printed out (step S 63 ). In a case where the printing of all the print data has not been completed (“NO” in step S 63 ), the controller  23  again causes the display  61  to display the request to press the certain key (step S 58 ). If the certain key is pressed (“YES” in step S 59 ), the controller  23  performs the printing of the next one page (step S 62 ). In a case where the certain key is not pressed during the input waiting time (“NO” in step S 59 , and “NO” in step S 60 ), the controller  23  ends the operation, and stores the printed page information in the data memory  25  (step S 61 ). 
       Fourth Exemplary Embodiment  
       [0058]    The following is a description of a fourth exemplary embodiment of the present invention, with reference to the accompanying drawings. Since the structure of this exemplary embodiment is also the same as the structure of the above-described second exemplary embodiment, explanation of it is omitted here. In the third exemplary embodiment, the operator is requested to press the certain key for the printing of each one page. In this exemplary embodiment, when the certain key is pressed, printing of print data within a predetermined print allowed time is allowed. Accordingly, printing of more than one page is allowed. 
         [0059]    Referring now to the flowchart shown in  FIG. 10 , an operation in accordance with this exemplary embodiment is described. Since the procedures from an input of authentication information till authentication in this exemplary embodiment are also the same as those of the first exemplary embodiment, explanation of them is omitted here. 
         [0060]    The controller  23  compares the authentication information input through the operation unit  60  with the authentication information extracted from the additional information, to determine whether they match (step S 76 ). If the input authentication information matches the extracted authentication information (“YES” in step S 76 ), the controller  23  causes the display  61  to display a screen for requesting the operator to press the certain key of the operation unit  60  (step S 78 ). In a case where the certain key has not been pressed during a predetermined input waiting time since the request to press the certain key (“NO” in step S 79 , and “NO” in step S 80 ), the controller  23  ends the operation, and stores “0” as the printed page information in a memory such as the RAM  43 . 
         [0061]    If the certain key is pressed within the input waiting time (“YES” in step S 79 ), the controller  23  reads one page of the print data stored in the data memory  25 , and causes the image processor  24  to convert the read print data into image data. The controller  23  then outputs the image data to the printer  26  to perform printing (step S 82 ). After the printing of the one page is finished, the controller  23  determines whether all the print data has been printed out (step S 83 ). In a case where the printing of all the print data has not been completed (“NO” in step S 83 ), the controller  23  determines whether the time elapsed since the pressing of the certain key is within the print allowed time (step S 84 ). If the elapsed time is within the print allowed time (“YES” in step S 84 ), the controller  23  reads the next one page of the print data stored in the data memory  25 , and performs the printing of the next one page (step S 82 ). In a case where the elapsed time is longer than the print allowed time (“NO” in step S 84 ), the controller  23  causes the display  61  to display the screen for requesting the operator to press the certain key of the operation unit  60  (step S 78 ), and stands by until the certain key is pressed (step S 79 ). If the certain key is pressed within the predetermined input waiting time (“YES” in step S 79 ), the controller  23  allows printing within the print allowed time. 
       Fifth Exemplary Embodiment  
       [0062]    The following is a description of a fifth exemplary embodiment of the present invention, with reference to the accompanying drawings. Since the structure of this exemplary embodiment is also the same as the structure of the above-described second exemplary embodiment, explanation of it is omitted here. 
         [0063]    In the above-described fourth exemplary embodiment, when the certain key is pressed, printing of print data is allowed within the predetermined print allowed time. 
         [0064]    In this exemplary embodiment, an LED or the like is used to indicate the remaining time of the print allowed time. The controller  23  changes the blinking rate of the LED, depending on the remaining time. The LED used for the display may be a LED  62  shown in  FIG. 3  for indicating that the power is on, or a LED  63  shown in  FIG. 3  for indicating that there is an error, or some other LED. 
         [0065]    The method of displaying the print allowed time involves not only adjusting the blinking rate of the LED, but also displaying the remaining time of the print allowed time on the display  61 . 
         [0066]    Referring now to the flowchart shown in  FIG. 11 , an operation in accordance with this exemplary embodiment is described. Since the procedures from an input of authentication information till authentication in this exemplary embodiment are also the same as those of the first exemplary embodiment, explanation of them is omitted here. 
         [0067]    The controller  23  compares the authentication information input through the operation unit  60  with the authentication information extracted from the additional information, to determine whether they match (step S 97 ). If the input authentication information matches the extracted authentication information (“YES” in step S 97 ), the controller  23  causes the display  61  to display a screen for requesting the operator to press the certain key of the operation unit  60  (step S 99 ). In a case where the certain key has not been pressed during a predetermined input waiting time since the request to press the certain key (“NO” in step S 100 , and “NO” in step S 101 ), the controller  23  ends the operation, and stores “0” as the printed page information in a memory such as the RAM  43 . If the certain key is pressed within the input waiting time (“YES” in step S 100 ), the controller  23  causes the LED to blink at a slow rate (step S 103 ). The controller  23  reads one page of the print data stored in the data memory  25 , and causes the image processor  24  to convert the read print data into image data. The controller  23  then outputs the image data to the printer  26  to perform printing (step S 104 ). After the printing of the one page is finished, the controller  23  determines whether all the print data has been printed out (step S 105 ). In a case where the printing of all the print data has not been completed (“NO” in step S 105 ), the controller  23  determines whether the time elapsed since the pressing of the certain key is within the print allowed time (step S 106 ). If the elapsed time is within the print allowed time (“YES” in step S 106 ), the controller  23  determines whether the remaining time till the end of the print allowed time is equal to or more than N (N being an integer) seconds (step S 107 ). If the remaining time is equal to or more than N seconds (“YES” in step S 107 ), the controller  23  reads the next one page of the print data from the data memory  25 , and performs the printing of the next one page (step S 104 ). If the remaining times is less than N seconds (“NO” in step S 107 ), the controller  23  makes the blinking rate of the LED faster (step S 108 ), and notifies the operator that the print allowed time will soon come to an end. The controller  23  then reads the next page of the print data from the data memory  25 , and performs the printing of the next page (step S 104 ). 
       Sixth Exemplary Embodiment  
       [0068]    The following is a description of a sixth exemplary embodiment of the present invention, with reference to the accompanying drawings. Since the structure of this exemplary embodiment is also the same as the structure of the above-described second exemplary embodiment, explanation of it is omitted here. 
         [0069]    In the above-described fourth and fifth exemplary embodiments, a print allowed time during which printing is allowed is set, and printing of two or more pages is allowed in the print allowed time. In this exemplary embodiment, when a certain key is pressed, printing of a predetermined number of pages is allowed. 
         [0070]    Referring now to the flowchart shown in  FIG. 12 , an operation in accordance with this exemplary embodiment is described. Since the procedures from an input of authentication information till authentication in this exemplary embodiment are also the same as those of the first exemplary embodiment, explanation of them is omitted here. 
         [0071]    The controller  23  compares the authentication information input through the operation unit  60  with the authentication information extracted from the additional information, to determine whether they match (step S 116 ). If the input authentication information matches the extracted authentication information (“YES” in step S 116 ), the controller  23  causes the display  61  to display a screen for requesting the operator to press the certain key of the operation unit  60  (step S 118 ). In a case where the certain key has not been pressed during a predetermined input waiting time since the request to press the certain key (“NO” in step S 119 , and “NO” in step S 120 ), the controller  23  ends the operation, and stores “0” as the printed page information in a memory such as the RAM  43  (step S 121 ). If the certain key is pressed within the input waiting time (“YES” in step S 119 ), the controller  23  reads one page of the print data stored in the data memory  25 , and causes the image processor  24  to convert the read print data into image data. The controller  23  then outputs the image data to the printer  26  to perform printing (step S 122 ). After the printing of the one page is finished, the controller  23  determines whether all the print data has been printed out (step S 124 ). In a case where the printing of all the print data has not been completed (“NO” in step S 124 ), the controller  23  determines whether the number of printed pages is the same as the number of pages allowed to be printed (step S 125 ). If the number of printed pages is the same as the number of pages allowed to be printed (“YES” in step S 125 ), the controller  23  causes the display  61  to display the screen for requesting the operator to press the certain key of the operation unit  60  (step S 118 ), and stands by until the certain key is pressed (step S 119 ). If the certain key is pressed within the predetermined input waiting time (“YES” in step S 119 ), the controller  23  allows printing of the next print allowed pages, which start from the next page to the last page printing has been completed (step S 122 ). 
         [0072]    The foregoing description of the exemplary 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 exemplary 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 exemplary embodiments and with 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.