Abstract:
An image forming apparatus includes a display device that displays an input screen image and a touch-panel arranged on the display device, and has a trial copy function of producing, when instructed to produce multiple copies of a document, a copy or copies to allow the user to confirm that the copy or copies are well. When the trial copy function is designated and a copy start key displayed on the input screen image is pressed, the image forming apparatus produces one copy or copies of the document, erases the copy start key from the input screen image, and displays a trial copy key, a trial end key and a balloon including help information. Since keys related to the trial copy are displayed in place of normally displayed keys, operation errors can be reduced and the user can easily execute the trial copy function.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This nonprovisional application claims priority under 35 U.S.C. §119(a) on Patent Application No. 2010-233429 filed in Japan on Oct. 18, 2010, the entire contents of which are hereby incorporated by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to an image forming apparatus and, more specifically, to an image forming apparatus having a trial copy function and a control method thereof. 
         [0004]    2. Description of the Background Art 
         [0005]    Recently, image forming apparatuses including copy machines having various and many copy functions and capable of high-speed copying have been put on the market. 
         [0006]    As the number of functions increases, it becomes difficult to handle skillfully the various and many functions of the device except for users who are familiar with such a device through daily use. Miscopies resulting from errors in operations for setting copy conditions are likely. Even if the user finds the setting error immediately after starting the copy, in a high-speed copy machine, a large number of copies would be taken before the once-started copy operation stops, wasting resources. 
         [0007]    Therefore, high-speed copiers having a “trial copy function” of providing only one copy before outputting a plurality of number of copies, and thereby allowing the user to confirm finished state, have been commercially available. Further, apparatuses having a function of displaying an expected state of an output image (preview function) on a display screen of an operation panel, and thereby allowing the user to confirm, have also been commercially available. Techniques related to copiers having the “trial copy function” and “preview function” are disclosed, for example, in Japanese Patent Laying-Open No. 2007-160790 (hereinafter referred to as &#39;790 Reference). 
         [0008]    &#39;790 Reference discloses a function allowing confirmation of output result before starting copying, by selecting either the “trial copy” or “preview display.” The user selects a desired course from an operation screen image displayed on a display unit of a touch-panel. 
         [0009]    Specifically, on an operation display unit shown in FIG. 2 of &#39;790 Reference, a liquid crystal display unit allowing touch input is provided near the central portion. On the right side of liquid crystal display unit, a group of hard keys (operation unit) including ten keys, an interruption key and a start key is provided, and a hard key for selecting the “trial copy” mode is provided therein. If the trial copy key is operated, the copy executed immediately thereafter will be in the trial copy mode. Specifically, after a document is scanned and read, the image based on the read image is not formed but once displayed as a preview image on the operation screen image (liquid crystal display unit) (see FIG. 6 of &#39;790 Reference). By operating a page feed key (left/right arrows for changing the display page, on the right side of preview image) displayed together with the preview image, it is possible to confirm the preview images by turning the preview images one by one. By touching “print stop” or “print continue” displayed at an upper right portion of the same screen display, it is possible to stop or continue the trial copy mode. 
         [0010]    According to the operation specification disclosed in &#39;790 Reference, keys having “print continue” and “print stop” indications thereon exist on the display screen and, in addition, a “start” key and a “clear/stop” key exist on the operation unit. The “print continue” and “print stop” can also be interpreted as start and stop of printing, respectively. This may leads to user&#39;s confusion as to which of the keys on the display screen and the keys on the operation unit are to be operated. Such a situation possibly causes erroneous operations of the user and, hence, there is still a possibility of miscopies, particularly a large number of miscopies in high-speed copiers. 
       SUMMARY OF THE INVENTION 
       [0011]    In view of the problem described above, it is desirable to provide an image forming apparatus allowing the user to execute the trial copy function in safety, without causing erroneous operation by the user. 
         [0012]    According to an aspect, the present invention provides an image forming apparatus including a display unit that displays an information input screen image allowing input of information, and an input unit that is arranged on the display unit and specifies a designated position on the information input screen image, and having a trial copy function of producing, when an instruction to produce multiple set of copies of a one- or multi-page document is given, a copy or a set of copies to allow a user to confirm that the copy or the set of copies are well; wherein if the trial copy function is designated and a position of one or a plurality of copy start keys displayed on the information input screen image is specified by the input unit, after the copy or the set of copies of the document are provided, the display unit erases the one or a plurality of copy start keys from the information input screen image, and displays a first key for executing the trial copy and a second key for producing copies of remaining number of set number of copies, on the information input screen image. 
         [0013]    Preferably, the display unit changes the one or a plurality of copy start keys to the first key or the second key. 
         [0014]    More preferably, the plurality of copy start keys include a monochrome copy start key and a color copy start key; and the display unit changes the monochrome copy start key and the color copy start key to the first key or the second key. 
         [0015]    Further preferably, the input unit is a touch-panel. 
         [0016]    Preferably, the first and second keys are displayed on an area of the information input screen image including an area where the one or a plurality of copy start keys are displayed adjacent to and parallel to each other. 
         [0017]    More preferably, the display unit displays first help information near the first key or the second key. 
         [0018]    Further preferably, the display unit displays second help information having the first help information of reduced amount, in place of the first help information in a prescribed situation. 
         [0019]    Preferably, the prescribed situation is when a piece of information to be newly displayed on the information input screen image is overlapped on the first help information, or when a position on the first help information displayed on the information input screen image is specified by the input unit. 
         [0020]    More preferably, the display unit displays the first help information in place of the second help information, if a position on the second help information displayed on the information input screen image is specified by the input unit. 
         [0021]    Further preferably, the display unit erases the copy start key from the information input screen image, displays a stop copy key to stop copying on the information input screen image and displays third help information near the stop copy key, in a time period from when the trial copy function is designated until one copy of the document is produced. 
         [0022]    According to another aspect, the present invention provides a method of controlling an image forming apparatus that includes a display unit that displays an information input screen image allowing input of information, and an input unit that is arranged on the display unit and specifies a designated position on the information input screen image, and has a trial copy function of producing, when an instruction to produce multiple set of copies of a one- or multi-page document is given, a copy or a set of copies to allow a user to confirm that the copy or the set of copies are well. The method includes the steps of: determining whether or not the trial copy function is designated; determining whether or not a position on one or a plurality of copy start keys displayed on the information input screen image is specified by the input unit; and if it is determined that the trial copy function is designated and a position on one or a plurality of copy start keys displayed on the information input screen is specified by the input unit, producing the copy or the set of copies of the document, erasing the one or a plurality of copy start keys from the information input screen image, and displaying a first key for executing the trial copy and a second key for producing copies of remaining number of set number of copies, on the information input screen image. 
         [0023]    Preferably, at the step of displaying the first and second keys on the information input screen image, the one or a plurality of copy start keys are changed to the first key or the second key. 
         [0024]    More preferably, the plurality of copy start keys include a monochrome copy start key and a color copy start key; and at the step of displaying the first and second keys on the information input screen image, the monochrome copy start key and the color copy start key are changed to the first key or the second key. 
         [0025]    Further preferably, the input unit is a touch-panel. 
         [0026]    Preferably, the first and second keys are displayed on an area of the information input screen image including an area where the one or a plurality of copy start keys are displayed adjacent to and parallel to each other. 
         [0027]    More preferably, the control method further includes the step of displaying first help information near the first key or the second key. 
         [0028]    Further preferably, the control method further includes the step of displaying second help information having the first help information of reduced amount, in place of the first help information, in a prescribed situation. 
         [0029]    Preferably, the prescribed situation is when a piece of information to be newly displayed on the information input screen image is overlapped on the first help information, or when a position on the first help information displayed on the information input screen image is specified by the input unit. 
         [0030]    More preferably, the control method further includes the step of displaying the first help information in place of the second help information, if a position on the second help information displayed on the information input screen image is specified by the input unit. 
         [0031]    Further preferably, the control method further includes the step of erasing the copy start key from the information input screen image, displaying a stop copy key to stop copying on the information input screen image and displaying third help information near the stop copy key, in a time period from when the trial copy function is designated until one copy of the document is produced. 
         [0032]    According to the present invention, a touch-panel is adopted as the information input device of an image forming apparatus, and in the trial copy mode, a trial copy key and a trial end key are displayed in place of the copy start key normally displayed on the task trigger area. Thus, error of key operation by the user can be prevented. 
         [0033]    Further, when one copy is to be printed as the trial copy, the user instructs copying by the normal copy start key and, thereafter, the trial copy key is displayed on the area where the normal copy start key has been displayed. Therefore, it is possible for the user to instruct trial copy with the same feeling of operation. 
         [0034]    Further, since help information related to the operation is displayed in a balloon near the keys operable in the trial copy mode, error in key operations by the user can further be reduced. 
         [0035]    Further, when a sub-screen (window) for function setting or the like is displayed to receive user operation, the balloon is displayed in a smaller size and, therefore, the balloon does not interfere with the operation by the user. Further, the balloon is not completely erased but left to indicate presence of help information, allowing the user to operate with ease. 
         [0036]    Further, while one copy is printed as a trial copy, unnecessary operation keys are hidden by the balloon and, therefore, error in key operations by the user during printing of one copy can be prevented. 
         [0037]    The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0038]      FIG. 1  is a perspective view showing an appearance of an image forming apparatus in accordance with an embodiment of the present invention. 
           [0039]      FIG. 2  is a functional block diagram showing hardware configuration of the image forming apparatus shown in  FIG. 1 . 
           [0040]      FIG. 3  is a plan view showing an information input device provided on the image forming apparatus shown in  FIG. 1 . 
           [0041]      FIG. 4  is a flowchart representing a control structure of a program for realizing the trial copy function in the image forming apparatus in accordance with an embodiment of the present invention. 
           [0042]      FIG. 5  is a flowchart representing a control structure of a program for realizing the continuation process shown in  FIG. 4 . 
           [0043]      FIG. 6  shows an example of a screen image before the trial copy function is selected, showing the same screen image as that of  FIG. 3 . 
           [0044]      FIG. 7  shows an example of a function list displayed when “other functions” key is pressed on the screen image of  FIG. 6 . 
           [0045]      FIG. 8  shows an example of a screen image displayed when the trial copy is selected on the screen image of  FIG. 7 . 
           [0046]      FIG. 9  shows an example of a screen image displayed when a monochrome start key or a color start key is pressed on the screen image of  FIG. 8 . 
           [0047]      FIG. 10  shows an example of screen image displayed after completion of output of one copy, in the trial copy mode. 
           [0048]      FIG. 11  shows an example of a screen image displayed when a trial end key is pressed, in the trial copy mode. 
           [0049]      FIG. 12  shows an example of a screen image displayed when a function setting key is pressed on the screen image of  FIG. 10 . 
           [0050]      FIG. 13  shows another example of the screen image displayed after completion of output of one copy, in the trial copy mode. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0051]    In the following description and the drawings, the same components are denoted by the same reference characters. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated. 
         [0052]    In the following, embodiments of the present invention will be specifically described with reference to appended figures. 
         [0053]    &lt;Image Forming Apparatus&gt; 
         [0054]    Referring to  FIG. 1 , an image forming apparatus  150  in accordance with an embodiment of the present invention includes: a document reading unit  152 ; an image forming unit  154 ; a paper feed unit  156 ; a discharge unit  158  having a paper discharge tray  160 ; and an information input device  162 . Information input device  162  is an operation console causing image forming apparatus  150  to execute prescribed functions, for making various settings related to the image forming apparatus  150 . Information input device  162  has a display unit  164  and an operation unit  166 . 
         [0055]    &lt;Hardware Blocks&gt; 
         [0056]    Referring to  FIG. 2 , inside image forming apparatus  150 , a CPU (Central Processing Unit)  180 , an ROM (Read Only Memory)  182 , an RAM (Random Access Memory)  184  and a HDD (Hard Disk Drive)  186  are provided. CPU  180  is for overall control of image forming apparatus  150 . ROM  182  stores programs and the like. RAM  184  is volatile storage. HDD  186  is non-volatile storage that retains data even when power is turned off. ROM  182  stores programs and data necessary for controlling operations of image forming apparatus  150 . Display unit  164  of information input device  162  is formed of a display panel  170  and a touch-panel  172 . Display panel  170  is a display device such as a liquid crystal display, and touch-panel  172  for detecting a pressed position is superposed thereon. 
         [0057]    Image forming apparatus  150  is further provided with an image processing unit  188 , an image memory  190 , a bus  192  and an NIC (Network Interface Card)  194 . CPU  180 , ROM  182 , RAM  184 , HDD  186 , information input device  162  (display panel  170 , touch-panel  172  and operation unit  166 ), NIC  194 , document reading unit  152 , image processing unit  188 , image memory  190 , image forming unit  154  and the like are connected to bus  192 . Data (including control information) are exchanged among these units through bus  192 . CPU  180  reads a program from ROM  182  to RAM  184  through bus  192 , and executes the program using a part of RAM  184  as a work area. Specifically, CPU  180  controls various units forming image forming apparatus  150  in accordance with a program or programs stored in ROM  182 , to realize various functions of image forming apparatus  150 . NIC  194  is connected to an external network  196 , and functions as an interface for communication through network  196 . 
         [0058]    &lt;Information Input Device&gt; 
         [0059]    Referring to  FIG. 3 , information input device  162  is formed by integrating display unit  164  and operation unit  166 . Specifically, operation unit  166  includes a home key  240 , a power key  242  and a power save key  244  as hard keys, and a power LED  246 . Power key  242  is for turning on/off the power supply to image forming apparatus  150 . Power save key  244  is for setting image forming apparatus  150  to a power save mode. Power LED  246  is lit when the power of image forming apparatus  150  is turned on. Home key  240  is a key for displaying a home screen image (a screen image on which frequently used functions are registered) on display unit  164 . 
         [0060]    The screen image displayed on display unit  164  includes a function setting area  200 , a preview area  210 , an action panel area  220  and a task trigger area  230 . On function setting area  200 , a plurality of keys (hereinafter also referred to as function setting keys) for setting various functions of image forming apparatus  150  are displayed. On function setting area  200  of  FIG. 3 , only a part of function setting keys is displayed. Function setting keys that are not displayed appear if “other functions” key  202  is pressed. Preview area  210  includes a ten key area  212  and a copy number display area  214 . The number of copies is input by the ten keys arranged on ten key area  212 . In  FIG. 3 , the number of copies is set to 14. 
         [0061]    On action panel area  220 , pieces of information related to assistance, guidance and suggestion related to the operation are displayed. For instance, if a user selects a specific function, functions related to the selected function are displayed on action panel area  220 . Other functions for objects common to the selected function may be displayed. 
         [0062]    On task trigger area  230 , keys as triggers causing image forming apparatus  150  to start certain processes are displayed. Specifically, a monochrome start key  232 , a color start key  234 , a scan-in key  236  and a CA key  238  are displayed. Monochrome start key  236  is for starting monochrome copy. Color start key  234  is for starting color copy. Scan-in key  236  is for starting a process for once reading a document and providing a preview for copying or for FAX transmission. CA key  238  is for clearing all settings. 
         [0063]    In information input device  162 , the state of image forming apparatus  150  and the job processing status are confirmed, by screen images displayed on display panel  17 Q. By selecting a key displayed on display panel  170  on touch-panel  172  superposed on display panel  170  (pressing the corresponding portion of touch-panel  172 ), function setting or operation instruction to image forming apparatus  150  can be realized. 
         [0064]    In information input device  162 , to determine whether or not a displayed key is pressed, known technique may be used. By way of example, correspondence between two-dimensional coordinates of touch-panel  172  and two-dimensional coordinates of display panel  170  is determined beforehand, and whether or not the position pressed on touch-panel  172  is included in any area of a letter or a figure displayed on display panel  170  is determined. 
         [0065]    &lt;Software Configuration&gt; 
         [0066]    In the following, a process in which information input device  162  is operated by the user and image forming apparatus  150  realizes the trial copy operation will be described. In the following, various processes are realized by CPU  180  executing programs read from ROM  182 . In the following, that a prescribed area displayed on display panel  170  (for example, a key) is pressed means that a corresponding portion of touch-panel  172  is pressed. 
         [0067]    Referring to  FIG. 4 , if the trial copy function is selected, at step  300  of the program for realizing the trial copy, CPU  180  displays information indicating that the operation is in the “trial copy” mode, on the screen image displayed on display panel  170 . 
         [0068]    The trial copy function can be selected from function setting area  200  displayed on a first screen image  600  of  FIG. 6 . Specifically, on the first screen image  600 , if other functions key  202  is pressed, a second screen image  610  shown in  FIG. 7  is displayed. In  FIG. 7 , on a function list display area  612  of the second screen image  610 , a list of functions is displayed. Since not all functions are displayed, a scroll bar  614  for scrolling the list display is displayed on the right side of function list display area  612 . In the second screen image  610 , if an area having the indication of “trial copy” is pressed, the trial copy function is selected. Here, selection is indicated by a thick line in  FIG. 7 . In this state, if a basic setting key  616  is pressed, display of function list display area  612  ends, and a different screen image is displayed. Specifically, a third screen image  620  shown in  FIG. 8  is displayed. The third screen image  620  is substantially the same as the first screen image  600  shown in  FIG. 6 , except that there is an indication  622  of “trial copy in progress” on the upper left portion of the screen image. 
         [0069]    With the third screen image  620  being displayed, at step  302 , CPU  180  determines whether or not color start key  234  has been pressed. If color start key  234  is pressed, control proceeds to step  304 . At step  304 , CPU  180  sets a parameter M for designating an image formation mode to “1”. Thereafter, control proceeds to step  306 . If color start key  234  is not pressed, control proceeds to step  330 . Parameter M is stored, for example, in RAM  184 . 
         [0070]    At step  330 , CPU  180  determines whether or not monochrome start key  232  has been pressed. If monochrome start key is pressed, control proceeds to step  332 . At step  332 , CPU  180  sets the parameter M for designating the image formation mode to “0”. Thereafter, control proceeds to step  306 . If monochrome start key  232  is not pressed, control proceeds to step  340 . 
         [0071]    At step  340 , CPU  180  determines whether or not CA key  238  has been pressed. If CA key  238  is pressed, control proceeds to step  342 . At step  342 , CPU  180  cancels the trial copy mode, and the present program ends. If CA key  238  is not pressed, control returns to step  302 . 
         [0072]    At step  306 , CPU  180  decreases the numerical value in a copy number display area  214  of the third screen image  320  by “1”. Further, at step  308 , CPU  180  changes the display of task trigger area  230  on the third screen image  620 . Specifically, CPU  180  displays a fourth screen image  630  shown in  FIG. 9 . In the fourth screen image  630 , the number of copies is changed to “13”, and monochrome start key  232  and color start key  234  are changed to stop copy key  632 . At the same time, a first balloon  638  including help information (information indicating the state of image forming apparatus  150  and information assisting the operation by the user) is displayed to hide scan-in key  236 . 
         [0073]    At step  310 , in accordance with the value of parameter indicating the image forming mode, CPU  180  controls document reading unit  152 , image processing unit  188 , image memory  190  and image forming unit  154  and thereby reads the document and executes color copy (when M=1) or monochrome copy (when M=0). Here the image data obtained by reading the document is stored in image memory  190 , and used when copy is taken at a subsequent step. 
         [0074]    With the fourth screen image  630  being displayed, at step  312 , CPU  180  determines whether or not stop copy key  632  is pressed. If stop copy key  632  is pressed, control proceeds to step  314 . At step  314 , CPU  180  stops copying and on the fourth screen image  630 , returns the copy number and the display of task trigger area  230  to the original state (that is, to the third screen image  620 ). Thereafter, control returns to step  302 . If stop copy key  632  is not pressed, control proceeds to step  316 . 
         [0075]    At step  316 , CPU  180  determines whether or not one copy (trial copy) is completed. If the one copy has not yet been completed, control returns to step  310  and if completed, control proceeds to step  318 . In this manner, through steps  310 ,  312 ,  314  and  316 , if a stop operation is made by the user during copying one trial copy, the one copy is stopped. 
         [0076]    At step  318 , CPU  180  changes the display in the task trigger area of the fourth screen image  630 , and after executing the continuation process of step  320 , ends the present program of realizing the trial copy function. Specifically, at step  318 , CPU  180  displays a fifth screen image  640  shown in  FIG. 10 , and waits for a user operation. When we compare the fifth screen image  640  with the preceding fourth screen image  630 , it can be seen that stop copy key  632  is changed to trial end key  642 , the first balloon  638  is erased and trial copy key  646  is displayed at that portion. In the fifth screen image  640 , a second balloon  648  including help information for assisting user operation is displayed. When we compare the fifth screen image  640  with the first screen image  600  and the third screen image  620 , it can be seen that monochrome start key  232  and color start key  234  are changed to trial end key  642 , and scan-in key  236  is changed to trial copy key  646 . 
         [0077]    Referring to  FIG. 5 , at step  500  of the program for realizing the continuation process at step  320 , with the fifth screen image  640  being displayed, CPU  180  determines whether or not trial copy key  646  has been pressed. If trial copy key  646  is pressed, control proceeds to step  308  and if not, control proceeds to step  510 . 
         [0078]    Steps  310 ,  312 ,  316  and  318  shown in  FIG. 5 , executed if trial copy key  646  is pressed, are the same as steps  310 ,  312 ,  316  and  318  of  FIG. 4 . Therefore, description thereof will not be repeated here. It is noted that step  502  executed if stop copy key  632  is pressed with the fourth screen image  630  being displayed at step  312  is different from step  314  shown in  FIG. 4 . At step  502 , CPU  180  simply stops copying, and the number of copies is not returned to the original value. Thereafter, control proceeds to step  318 . 
         [0079]    At step  510 , with the fifth screen image  640  being displayed, CPU  180  determines whether or not trial end key  642  has been pressed. If trial end key  642  is pressed, control proceeds to steps  512  to execute copying of remaining number, and if not, control proceeds to step  520 . 
         [0080]    At step  512 , CPU  180  changes the display of task trigger area  230  of the fifth screen image  640 . Specifically, CPU  180  displays the sixth screen image  650  shown in  FIG. 11 . In the sixth screen image  650 , trial end key  642  of the fifth screen image  640  is changed to stop copy key  632 , and the second balloon  648  is erased. Further, a third balloon including help information indicating that copying is in progress is displayed on trial copy key  646 . 
         [0081]    At step  514 , in accordance with the value of parameter M indicating the image forming mode, CPU  180  controls image processing unit  188 , image memory  190  and image forming unit  154  and executes color copy (when M=1) or monochrome copy (when M=0), to provide the remaining number of copies (here, 13 copies). Every time printing of one copy ends, CPU  180  decreases the number of printing displayed on the screen image by “1”. Here, since image data read and stored in image memory  190  at step  310  is used, document reading unit  152  is not driven. 
         [0082]    With the sixth screen image  650  being displayed, at step  312 , CPU  180  determines whether or not stop copy key  632  has been pressed. If stop copy key  632  is pressed, control proceeds to step  502 . At step  510 , CPU  180  stops copying, and on the sixth screen image  650 , returns the display of task trigger area  230  to the original state (that is, to the fifth screen image  640 ). Thereafter, control returns to step  302 . If stop copy key  632  is not pressed, control returns to step  516 . 
         [0083]    At step  516 , CPU  180  determines whether or not copying of the remaining number of copies has been all completed. By way of example, using a parameter representing the number of copies displayed on the screen image, by decreasing the parameter value by “1” every time one copy is printed, it is possible to determine whether all copies have been completed, by checking whether or not the parameter value is “0”. If not all copies have been completed, control returns to step  514 . If all copies are completed, the control returns to the main routine and the present program ends. In this manner, through steps  514 ,  312  and  516 , if a stop operation by the user is received while the process of copying the remaining number is being executed, the copy operation is stopped. 
         [0084]    At step  520 , CPU  180  determines whether or not a function setting key in function setting area  200  of the fifth screen image  640  has been pressed. If any function setting key is pressed, control proceeds to step  522 . At step  522 , CPU  180  displays a corresponding setting screen image, and waits for user operation.  FIG. 12  shows an example when a magnification key is selected as the function setting key. On a seventh screen image  660  shown in  FIG. 12 , a magnification setting window  662  is displayed overlapped on the fifth screen image  640 , and in place of the second balloon  648 , a fourth balloon  668  is displayed. When magnification setting window is displayed, the second balloon interferes with the view and, therefore, the fourth balloon  668  including only the information that the second balloon  648  exists and not the specific help information, is displayed. 
         [0085]    Setting of copy magnification using magnification setting window  662  is realized by pressing a key of percentage indication and thereby directly designating the magnification, or by designating a numerical value in the range of 25 to 400 by pressing up and down keys  664 . After the completion of setting, magnification setting window  662  is closed (for example, the sign “x” at the upper right corner is pressed), and then the display returns to the fifth screen image  640 , in which the second balloon  648  including the help information appears in place of the fourth balloon  668 . 
         [0086]    In this manner, if trial end key  642  or trial copy key  646  is pressed after a function setting key is pressed and the function setting is changed, the copy process is executed in accordance with the changed conditions, at step  310  or at step  514 . 
         [0087]    Step  340  of determining whether or not CA key  238  has been pressed, and step  342  executed if CA key  238  is pressed, are the same as steps  340  and  342  shown in  FIG. 4 . Therefore, description thereof will not be repeated here. It is noted, however, that at step  340  shown in  FIG. 5 , if CA key  238  is not pressed, control returns to step  500 . 
         [0088]    As described above, when the user uses the trial copy function and makes one copy at first, it is possible for the user to start copying by pressing the normal copy start key (monochrome start key  232  or color start key  234 ) displayed on the task trigger area. Copy instruction thereafter can be given by using trial end key  642  and trial copy key  646 , which are different from the normal copy start keys, displayed on the task trigger area. Specifically, the user evaluates the result of one copy, and if it is unsatisfactory, he/she may change setting by using the function setting key or keys, and then by pressing trial copy key  646 , the user can repeat printing one copy until satisfactory result is obtained. After the satisfactory finish is obtained, the remaining number of copies can be taken by pressing trial end key  642 . In this manner, since the keys related to trial copy are displayed in place of normally displayed keys in the task trigger area, erroneous operation by the user can be reduced, and the user can safely execute the trial copy function. 
         [0089]    Further, in the trial copy mode, help information is displayed in a balloon in or around the task trigger area and, therefore, erroneous operation by the user can further be reduced. 
         [0090]    In the foregoing, an example has been described in which monochrome start key  232  and color start key  234  of the third screen image  620  are changed to trial end key  642  in the fifth screen image  640 , and scan-in key  236  of the third screen image  620  is changed to trial copy key  646  in the fifth screen image  640 . The example, however, is not limiting. By way of example, a trial end key  702  and a trial copy key  706  may be displayed as shown in the eighth screen image  700  of  FIG. 13 . In the eighth screen image  700 , the positions of trial end key and trial copy key are reversed from the fifth screen image  640 . Specifically, in the eighth screen image  700  shown in  FIG. 13 , monochrome start key  232  and color start key  234  of the third screen image  620  are changed to trial copy key  706 , and scan-in key  236  of the third screen image  620  is changed to trial end key  702 . 
         [0091]    Further, the positions for displaying the first to fourth balloons are not limited to the positions described above. Specifically, the first balloon  638  and the third balloon  658  displayed during the copying operation are used for displaying the state of image forming apparatus  150  and, besides, for hiding unnecessary keys displayed in the task trigger area. Therefore, the first and third balloons  638  and  658  may be displayed in any manner provided that keys other than stop copy key  632  and CA key  238  that may be operated during the copying operation are hidden. These balloons may be displayed with the size and position changed appropriately in accordance with the key arrangement in the task trigger area. 
         [0092]    Further, the condition for displaying the second balloon  648  in a smaller size such as the fourth balloon  668  is not limited to the condition described above (when function setting is to be done), and it may be displayed in a smaller size when a different condition is satisfied. For example, the second balloon  648  may be displayed in a smaller size if it is pressed; or if a prescribed time passes after the second balloon  648  is displayed. 
         [0093]    Further, the condition for returning the displayed small fourth balloon  668  to the original second balloon  648  is not limited to the condition described above (when function setting is completed). By way of example, the second balloon  648  may be displayed if the fourth balloon  668  is pressed. 
         [0094]    Though an image forming apparatus capable of monochrome copy and color copy has been described as an example, it is not limiting. For instance, the image forming apparatus may have the monochrome copy function only and may not have the color copy function. In that case, the color start key is not displayed on the display panel and a simple copy start key (corresponding to the monochrome start key) is displayed. When the trial copy function is to be executed, the copy start key may be changed to the trial copy key or to the trial end key. 
         [0095]    The embodiments as have been described here are mere examples and should not be interpreted as restrictive. The scope of the present invention is determined by each of the claims with appropriate consideration of the written description of the embodiments and embraces modifications within the meaning of, and equivalent to, the languages in the claims.