Abstract:
An image formation apparatus is provided for supporting adjustment of the distance between a heat roller and a heating unit for heating the heat roller, thereby supporting adjustment of supplied power to the heating unit. The image formation apparatus includes a heat roller for clamping paper with a toner image formed thereon with a pressurization roller; a heating unit being placed facing the heat roller for heating the heat roller; a power supply unit for supplying power to the heating unit; an acquisition unit for acquiring a power value based on the power supplied from the power supply unit; a comparison unit for making a comparison between the power value acquired by the acquisition unit and a predetermined power value; and a display unit for displaying information concerning adjustment of a distance from the heat roller to the heating unit based on the comparison result of the comparison unit.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates to an image formation apparatus using induction heating and a heat roller adjustment support method. 
   2. Description of the Related Art 
   In an image formation apparatus using induction heating, a heat roller, etc., is a consumable and thus needs to be replaced. 
   However, if an old heat roller is replaced with a new one, an error occurs between the placement positions of the heat rollers before and after the replacement and therefore the distance (gap) from the new heat roller to an induction heating coil does not necessarily become constant. If a heat roller placement error thus occurs, a change also occurs in power output because the gap varies and desired power output cannot be obtained. If power which is not desired power is thus output, a problem may occur in a fixing state between a toner image and paper. 
   SUMMARY OF THE INVENTION 
   It is an object of the invention to provide an image formation apparatus of induction heating and a heat roller adjustment support method for calculating the power value of power supplied to a coil and supporting the user so as to optimize the gap between the coil and a heat roller based on the calculation result. 
   To solve the above-described problems, according to one aspect of the invention, there is provided an image formation apparatus including a heat roller containing an electric conductor, for clamping paper with a toner image formed thereon with a pressurization roller; a heating unit being placed facing the heat roller for heating the heat roller; a power supply unit for supplying power to the heating unit; an acquisition unit for acquiring a power value based on the power supplied from the power supply unit; a comparison unit for making a comparison between the power value acquired by the acquisition unit and a predetermined power value; and a display unit for displaying information concerning adjustment of a distance from the heat roller to the heating unit based on the comparison result of the comparison unit. 
   According to one aspect of the invention, there is provided an image formation apparatus including heating means being placed facing a heat roller containing an electric conductor, for clamping paper with a toner image formed thereon with a pressurization roller, the heating means for heating the heat roller; power supply means for supplying power to the heating means; acquisition means for acquiring a power value based on the power supplied from the power supply means; comparison means for making a comparison between the power value acquired by the acquisition means and a predetermined power value; and display means for displaying information concerning adjustment of a distance from the heat roller to the heating means based on the comparison result of the comparison means. 
   According to one aspect of the invention, there is provided a heat roller adjustment support method of supplying power to a heating unit being placed facing a heat roller containing an electric conductor, for clamping paper with a toner image formed thereon with a pressurization roller, the heating unit for heating the heat roller; acquiring a power value based on the supplied power; making a comparison between the acquired power value and a predetermined power value; and displaying information concerning adjustment of a distance from the heat roller to the heating unit based on the comparison result. 

   
     DESCRIPTION OF THE DRAWINGS 
     In the accompanying drawings: 
       FIG. 1  is a diagram to show an example of an induction heating circuit included in an image formation apparatus according to an embodiment of the invention; 
       FIG. 2  is a block diagram to show an example of the functions implemented by a microcomputer, a voltage detection circuit, a current detection circuit, and a liquid crystal panel of the image formation apparatus according to the embodiment of the invention; 
       FIG. 3  is a flowchart to show an example of processing of adjustment support of a heat roller according to the embodiment of the invention; 
       FIG. 4  is a drawing to show an example of display of a display section according to the embodiment of the invention; and 
       FIG. 5  is a drawing to show an example of a gap adjustment mechanism included in the image formation apparatus according to the embodiment of the invention. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring now to the accompanying drawings, there is shown an embodiment of the invention. 
     FIG. 1  is a diagram to describe an induction heating circuit in an image formation apparatus according to the embodiment of the invention. 
   An induction heating circuit  100  includes a microcomputer  10  for controlling the whole of an image formation apparatus  1  and a drive circuit  11  for controlling so as to drive at a drive frequency corresponding to output power. The induction heating circuit  100  also includes a resonance circuit  15 , which includes an IGBT (Insulated Gate Bipolar Transistor) element  13  and a coil  14  (heating unit, heating means) and a capacitor  21  joined to the IGBT element  13 . Power is supplied to the resonance circuit  15  via an AC power supply  16  (power supply unit, power supply means) and a rectifying circuit  17  and thus power is also supplied to the coil  14 . 
   The induction heating circuit  100  also includes a voltage detection circuit  18  for detecting voltage of the AC power supply  16  and a current detection circuit  19  for detecting a current through a current transformer  20 . The data detected by the detection circuits is fed back into the microcomputer  10 . 
   The microcomputer  10  includes the functions of a power value calculation unit  41 , a comparison unit  3  (comparison means), and a display information acquisition unit  42  in cooperation with firmware (not shown). The power value calculation unit  41  calculates a power value from the voltage detected by the voltage detection circuit  18  and the current detected by the current detection circuit  19 . The comparison unit  3  makes a comparison between the power value calculated by the power value calculation unit  41  and a previously defined power value (predetermined power value). 
   The display information acquisition unit  42  acquires information concerning adjustment of the distance (gap) from a heat roller  30  (described later) to the coil  14  based on the comparison result of the comparison unit  3 . 
   The display information acquisition unit  42  may acquire the information concerning adjustment of the gap by calculating the information using the power value calculated by the power value calculation unit  41  and a predetermined computation expression in the firmware or may acquire the information concerning adjustment of the gap based on a table previously defining the correspondence between the information concerning adjustment of the gap and the power value calculated by the power value calculation unit  41 . 
   A liquid crystal panel  22  connected to the microcomputer  10  displays the information acquired by the display information acquisition unit  42  for the user. 
   Next, the functions implemented by the microcomputer  10 , the voltage detection circuit  18 , the current detection circuit  19 , and the liquid crystal panel  22  will be discussed with reference to  FIG. 2 . 
   The image formation apparatus  1  includes an acquisition unit  2  (acquisition means), the comparison unit  3 , and a display unit  4  (display means). The acquisition unit  2  acquires the power value based on the power supplied from the AC power supply  16 . The comparison unit  3  makes a comparison between the power value acquired by the acquisition unit  2  and the previously defined power value, as described above. The display unit  4  displays the information concerning adjustment of the gap based on the comparison result of the comparison unit  3 . 
   The acquisition unit  2  corresponds to the voltage detection circuit  18 , the current detected by the current detection circuit  19 , and the power value calculation unit  41 , and the display unit  4  corresponds to the display information acquisition unit  42  and the liquid crystal panel  22 . 
   Processing of adjustment support of the heat roller will be discussed with reference to a flowchart of  FIG. 3 . In the image formation apparatus  1  in the embodiment, for example, if the previously defined power value is 900 W and the microcomputer  10  gives a command for outputting 900 W, the drive circuit  11  drives at drive frequency 50 kHz. 
   After power is input in the AC power supply  16  (step S 1 ), the acquisition unit  2  acquires the power value by acquiring the current and the voltage (power) of the coil  14  (step S 2 ). The comparison unit  3  determines whether or not the power value acquired by the acquisition unit  2  is the previously defined power value, 900 W (step S 3 ). 
   If the output value is 900 W (YES at step S 3 ), the image formation apparatus  1  terminates the processing of heat roller adjustment support. On the other hand, if the output value is not 900 W (NO at step S 3 ), then the comparison unit  3  makes a comparison between the power value acquired by the acquisition unit  2  and the previously defined power value, 900 W (step S 4 ). 
   If the output value is larger than 900 W (YES at step S 4 ), the display unit  4  displays a message for requesting the user to widen the gap by 0.1 mm as the information concerning adjustment of the gap on the liquid crystal panel  22  (step S 5 ). On the other hand, if the output value is less than 900 W (NO at step S 4 ), the display unit  5  displays a message for requesting the user to narrow the gap by 0.1 mm as the information concerning adjustment of the gap on the liquid crystal panel  22  (step S 6 ). 
   The user checks the description displayed on the liquid crystal panel  22  and adjusts the gap between the coil  14  and the heat roller  30  with a gap adjustment mechanism  200  (described later) (step S 7 ). After this, again the acquisition unit  2  acquires the power value (loop from step S 7  to step S 2 ). Thus, the power value acquisition, comparison, and display and the adjustment of the gap are repeated until the power value reaches the desired value 900 W. 
   The principle on which the power output changes with the gap change will be discussed. If the gap between the heat roller  30  (which contains an electric conductor) and the coil  14  is narrowed, the reactance (L) of the resonance circuit  15  increases; if the gap is widened, the reactance lessens. Since the resonance frequency is f=(2π(LC) 1/2 ) −1  (C: Electric capacitance of capacitor), as the reactance changes, the frequency changes. Therefore, the power output corresponding to the frequency changes. 
     FIG. 4  shows an example of the descriptions displayed on the liquid crystal panel  22  of the display unit  4 . The display unit  4  displays the power value (output wattage) acquired by the acquisition unit  2  and displays the difference between the preset reference value (900 W) and the current output wattage. The display unit  4  also displays the turning direction of an adjustment screw  31  (described later) of the gap adjustment mechanism  200  and the number of turns of the screw as the information concerning adjustment of the gap based on the power value acquired by the acquisition unit  2 . The display unit  4  may display the amount of widening (or narrowing) the gap as the information concerning adjustment of the gap, as shown above in the flowchart. 
   Next, an example of the gap adjustment mechanism in the embodiment will be discussed with reference to  FIG. 5 . The gap adjustment mechanism  200  (adjustment unit, adjustment means) includes the adjustment screw  31  (varying means), a seesaw  33  (transmission unit, transmission means), and a side wall  34  (support unit, support means) for adjusting the gap between the heat roller  30  containing an electric conductor and the coil  14  placed facing the heat roller  30 . 
   The adjustment screw  31  varies in an X axis direction as the user adds turning movement relative to an X axis (predetermined axis), for example. The adjustment screw  31  pierces the side wall  34  and is supported by the side wall  34 . 
   The seesaw  33  has both end parts in contact with an end part of the adjustment screw  31  and the coil  14  and transmits a force so that the position of the coil  14  relative to the heat roller  30  varies based on variation of the position of the adjustment screw  31 . The seesaw  33  is shaped like a letter L and has the right angle point as a supporting point. According to the structure, if the adjustment screw  31  moves in a negative direction relative to the X axis, the coil  14  moves in a positive direction through the seesaw  33 ; whereas, if the adjustment screw  31  moves in the positive direction relative to the X axis, the coil  14  moves in the negative direction through the seesaw  33 . 
   The adjustment amount the gap between the heat roller  30  and the coil  14  is minute with respect to the move amount of the adjustment screw  31  by the user. Therefore, the seesaw  33  needs to have the supporting point (the right angle point in the shape of the letter L) at a position where the linear distance with the adjustment screw  31  is longer than the linear distance with the end part in contact with the coil  14 . 
   The user turns the head of the adjustment screw  31  with a tool, etc., based on the description displayed on the liquid crystal panel  22  to adjust the position of the adjustment screw  31 , thereby adjusting the gap between the heat roller  30  and the coil  14  so that the predetermined output power (in the embodiment, 900 W) is reached. 
   In the embodiment, the coil  14  is moved relative to the heat roller  30 ; in contrast, however, the heat roller  30  may be moved relative to the coil  14 . 
   In the embodiment, the seesaw  33  is shaped like a letter L, but may be of any shape if the condition of the position of the supporting point is satisfied. If fine adjustment can be made with the adjustment screw, the gap adjustment mechanism  200  may adopt a structure in which the seesaw  33  is not used and the adjustment screw  31  and the coil  14  are directly joined. 
   In the embodiment, the information concerning adjustment of the gap, etc., is displayed using the liquid crystal panel  22 , but the mode is not limited; for example, a voice guidance may be used. 
   In the embodiment, the output of the coil  14  is calculated based on detection of the current detection circuit  19  and the voltage detection circuit  18 , but the embodiment is not limited to the mode. For example, the drive frequency of the coil  14  may be changed for making an adjustment so as to output 900 W. To change the drive frequency, if the output is lower than 900 W, setting is changed so as to decrease the drive frequency in 100-Hz units; if the output is larger than 900 W, setting is changed so as to increase the drive frequency in 100-Hz units. In this case, for the adjusted drive frequency, the value of a table retained in memory in the drive circuit  11  may be rewritten. 
   The frequency of the current flowing into the coil  14  may be measured by measuring the current flowing into the resonance circuit  15 . In this case, for example, if the microcomputer gives a command to the drive circuit so as to drive at 50 kHz, it is necessary to detect whether or not the drive circuit actually drives at 50 kHz. 
   While the specific form of the invention has been described in detail, it is to be understood that various changes and modifications will be apparent to those skilled in the art without departing from the spirit and the scope of the invention. 
   As described above in detail, according to the invention, adjustment of the distance from the heat roller to the heating unit is supported, so that adjustment of supplied power to the heating unit can be supported.