Image formation apparatus, heating method, and program

Abstract

To provide an image formation apparatus, a heating method, and a program which can obtain the appropriate amount of heat at a heating unit without a configuration of having two heaters so as to switch between series and parallel connections even when used input voltages differ.SOLUTION: An image formation apparatus 1 includes: a heating unit 311; reception units 200, 700 for receiving a plurality of types of input voltages; and determination units 400, 500, 600 for determining such timing that current flows through the heating unit 311 according to the input voltages received by the reception units.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus such as a copying machine, a printer, or a multi-function digital multifunction machine called an MFP, which has a heating unit such as a heater of a fixing device, a heating method, and a program. [Background technology]

[0002] Image forming apparatuses having a fixing unit as described above are widely distributed around the world. However, since the commercial power supply voltage differs from region to region, it has been necessary to separate the destinations according to the input voltage used.

[0003] A heater, which is a heat source for a fixing device that heats and fixes toner on a recording medium such as paper, has the characteristic that the higher the input voltage relative to its rated voltage, the greater the current, power, and heat generation. If the heater is not designated for separate use and the rated voltage is set to match a 100V commercial power area and is also used in a 200V commercial power area, the current and power will be greater in the 200V commercial power area, and the amount of heat generated will also increase. This can cause problems such as the current exceeding the rated outlet, or the increased amount of heat causing large variations in the temperature at which the toner is heated and fixed, resulting in image abnormalities.

[0004] In addition, if the rated voltage is set to match that of a 200V commercial power area and then used in a 100V commercial power area, the current and power will be smaller in the 100V commercial power area, and the amount of heat will decrease. As a result, the toner cannot be sufficiently heated and fixed, resulting in image abnormalities.

[0005] To avoid such problems, it was necessary to categorize heaters according to the input voltage used.

[0006] On the other hand, Patent Document 1 discloses a technology that eliminates the need for a heater by switching the operation mode of the heat source at two input voltages, low input voltage and high input voltage. In this technology, for example, the heater is divided into two, and at low input voltage, it operates in an operation mode where the heaters are connected in parallel, and at high input voltage, it operates in an operation mode where the heaters are connected in series, so that an appropriate amount of heat can be obtained regardless of the input voltage. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2008-003469 A Summary of the Invention [Problem to be solved by the invention]

[0008] However, the technology described in Patent Document 1 requires splitting the heater into two and a switch element for switching between series and parallel, which is expensive and poses other problems in that the fixing unit becomes large.

[0009] An object of the present invention is to provide an image forming apparatus, a heating method, and a program that can obtain an appropriate amount of heat for the heating section even when different input voltages are used, without having to split the heater into two and switch between series and parallel. [Means for solving the problem]

[0010] The above object can be achieved by the following means. (1) a heating unit; A reception unit that receives a plurality of types of input voltages; a determination unit that determines a timing at which a current flows to the heating unit in response to the input voltage received by the reception unit; An image forming apparatus comprising: (2) The image forming apparatus according to the above item 1, further comprising a voltage detection unit that detects an input voltage, and determines a timing at which a current flows to the heating unit depending on a detection result of the voltage detection unit. (3) An image forming apparatus as described in the preceding paragraph 1 or 2, further comprising a temperature detection means for detecting the temperature of the heating section, and determining the timing at which current flows to the heating section depending on the detection results of the voltage detection means and the temperature detection means. (4) The image forming apparatus according to the above item 1 or 2, wherein an upper limit value of a current flowing through the heating portion is switched depending on a type of an input voltage. (5) The image forming apparatus according to item 1 or 2, wherein when the input voltage is relatively low, the upper limit of the current flowing through the heating unit is set higher than when the input voltage is relatively high. (6) The image forming apparatus according to item 1 or 2, wherein the upper limit of the current flowing through the heating section is set to a value at which the power of the heating section is equal to or lower than a predetermined value. (7) A control means for controlling a current flowing through the heating unit by PWM control, 3. The image forming apparatus according to claim 1, wherein the control means switches the current by changing a PWM duty ratio within a half cycle of the input current. (8) A control means for phase-controlling a current flowing in the heating section is provided, 3. The image forming apparatus according to claim 1, wherein the control means switches the current by changing a conduction angle to the heat generating means. (9) The image forming apparatus according to the above item 1 or 2, wherein the current flowing through the heating section is switched by turning the current on and off in units of a half cycle of an input voltage. (10) An acquisition unit for acquiring information about an area where the image forming apparatus is installed and determining the area, 3. The image forming apparatus according to claim 1 or 2, wherein an upper limit value of the current flowing to the heating unit is set to a value corresponding to the region determined by the acquisition means. (11) An image forming apparatus having a heating unit, a receiving step of receiving a plurality of types of input voltages; a determination step of determining a timing at which a current flows to the heating unit in response to the input voltage received in the receiving step; A heating method comprising the steps of: (12) In a computer of an image forming apparatus having a heating unit, a receiving step of receiving a plurality of types of input voltages; a determination step of determining a timing at which a current flows to the heating unit in response to the input voltage received in the receiving step; A program for executing. Effect of the Invention

[0011] According to this invention, multiple types of input voltages are accepted, and the timing at which current flows to the heating section is determined according to the accepted input voltage, so an appropriate amount of heat can be obtained even if different input voltages are used. Therefore, there is no need to provide a configuration in which the heater is divided into two and switched between series and parallel, so that it is possible to avoid an increase in size and cost of the fixing unit, etc. [Brief description of the drawings]

[0012] [Figure 1] 1 is a schematic diagram of an image forming apparatus according to an embodiment of the present invention; [Diagram 2] FIG. 2 is a circuit diagram of a heater control circuit according to the first embodiment. [Diagram 3] 11 is a table showing an example of adjustment values ​​of the duty ratio when the temperature of the heating roller exceeds a set value or falls below a set value. [Figure 4] 1A to 1C are waveform diagrams showing an example of an input voltage Vin, a PWM signal S2, and a current Ihe flowing through a halogen heater in the first embodiment, and FIG. 1D is an enlarged view of a portion of the PWM signal S2 and the current Ihe. [Diagram 5] 1 is a table showing an example of an upper limit current value Ihemax, an upper limit power value Whemax, and an upper limit on-duty ratio dutymax with respect to an input voltage Vin in the first embodiment. [Figure 6] FIG. 6 is a circuit diagram of a heater control circuit according to a second embodiment. [Figure 7]13(A) to 13(C) are waveform diagrams showing an example of an input voltage Vin, a phase control signal S4, and a current Ihe flowing through a halogen heater in the second embodiment, respectively. [Figure 8] 13 is a table showing an example of an upper limit current value Ihemax, an upper limit power value Whemax, and a lower limit value θmin of an on-phase angle with respect to an input voltage Vin in the second embodiment. [Figure 9] FIG. 11 is a circuit diagram of a heater control circuit according to a third embodiment. [Figure 10] 13(A) to 13(C) are waveform diagrams showing an example of an input voltage Vin, a half-wave control signal S5, and a current Ihe flowing through a halogen heater 311, respectively, in the third embodiment. [Figure 11] 13 is a table showing an example of an upper limit current value Ihemax, an upper limit power value Whemax, and an upper limit value HCmax of an on half wave number with respect to an input voltage Vin in the third embodiment. [Figure 12] FIG. 11 is a circuit diagram of a heater control circuit according to a fourth embodiment. [Figure 13] 13 is a table showing an example of an upper limit current value Ihemax, an upper limit power value Whemax, and an upper limit on-duty ratio dutymax with respect to an input voltage Vin in each target area in the fourth embodiment. [Figure 14] FIG. 13 is a circuit diagram of a heater control circuit according to a fifth embodiment. [Figure 15] 13 is a table showing an example of an upper limit current value Ihemax, an upper limit power value Whemax, and a lower limit value θmin of an on-phase angle with respect to an input voltage Vin in each target area in the fifth embodiment. [Figure 16] FIG. 13 is a circuit diagram of a heater control circuit according to a sixth embodiment. [Figure 17] 23 is a table showing an example of an upper limit current value Ihemax, an upper limit power value Whemax, and an upper limit value HCmax of an on half wave number with respect to an input voltage Vin in each target area in the sixth embodiment. [Figure 18] 23 is a table showing an example of an upper limit current value Ihemax, an upper limit power value Whemax, and an upper limit on-duty ratio dutymax with respect to an input voltage Vin in each target area in the seventh embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0014] FIG. 1 is a diagram showing a schematic configuration of an image forming apparatus according to a first embodiment of the present invention.

[0015] The image forming apparatus 1 is configured with a paper feed section 2 disposed at the bottom of the device body 1A, a color image forming section 3 disposed in the center, and a paper discharge section 4 disposed at the top. A sheet transport path 20 is provided between the paper feed section 2 and the paper discharge section 4 to transport the sheet (paper) S fed from the paper feed section 2 upward.

[0016] The color image forming section 3 includes a drive roller 51 and a driven roller 50 arranged approximately in the vertical center of the device main body 1A, an intermediate transfer belt 60 that is horizontally suspended between the drive and driven rollers 51, 50 and runs in the direction of the arrow, and imaging units 62Y, 62M, 62C, and 62K for each of the colors yellow (Y), magenta (M), cyan (C), and black (K) arranged along this running direction.

[0017] The toner images created by the imaging units 62Y, 62M, 62C, and 62K are superimposed and transferred onto the transfer belt 60, and a secondary transfer is performed on the sheet S conveyed along the sheet conveying path 20 at the conveying end (the right end in the figure) of the transfer belt 60, and the sheet S is fed to a nip portion formed by a heating roller 310 and a pressure roller 320 of the fixing section 300 to fix the toner image. The heating roller 310 is provided with a heater 311 for heating the heating roller 310 to a predetermined temperature.

[0018] Each of the imaging units 62Y, 62M, 62C, and 62K creates an image by electrostatic copying, and includes an exposure section 40 equipped with a print head 41 having a charger, four laser diodes, a polygon mirror, and a scanning lens, etc., arranged around the imaging units, four reflecting mirrors 42, etc., developers 61Y, 61M, 61C, and 61K, a photosensitive drum, a transfer unit, etc.

[0019] In addition, toner cartridges 70Y, 70M, 70C, 70K and sub hoppers 80Y, 80M, 80C, 80K are arranged above the image creating units 62Y, 62M, 62C, 62K as supply mechanisms for supplying toner to the developers 61Y, 61M, 61C, 61K of each image creating unit 62Y, 62M, 62C, 62K.

[0020] Reference numeral 9 denotes a control unit, and reference numeral 5 denotes an operation panel unit equipped with a key unit and a display unit. The control unit 9 comprehensively controls the entire image forming apparatus 1, and includes a CPU 91, a ROM 92, a RAM 93, a storage unit 94, etc.

[0021] The CPU 91 operates according to an operation program to realize various functions of the image forming apparatus 1. The ROM 92 stores various setting values ​​and the like required for the operation of the image forming apparatus 1. The RAM 93 loads the operation program of the CPU 91 and provides a working area for the CPU 91 to operate. The storage unit 94 stores the operation program of the CPU 91, other applications, various data, and the like.

[0022] Reference numeral 10 denotes a power supply circuit. The power supply circuit 10 converts AC power from a commercial power source in the area where the image forming apparatus 1 is used into DC power of a constant voltage, or supplies the DC power to each load of the image forming apparatus 1, including the heater 311 of the fixing unit 300, with or without conversion.

[0023] However, if the voltage of the commercial power source (the input voltage of the power supply circuit 10) differs depending on the country or region where the image forming apparatus 1 is used, the amount of heat generated by the heater 311 will not be an appropriate value. This will result in poor image fixing and failure to perform the desired fixing.

[0024] Therefore, in this embodiment, a heater control circuit is provided to ensure an appropriate amount of heat generated by heater 311 even when the input voltage varies, without requiring a complex configuration as described in the prior art. [First embodiment] FIG. 2 is a circuit diagram of the heater control circuit according to the first embodiment.

[0025] This heater control circuit includes an AC power supply 101 and a rectifier circuit 102 that full-wave rectifies the AC voltage from the AC power supply 101. An input voltage detection unit 200 (corresponding to a receiving unit) that detects the voltage value (effective value) of the input voltage Vin from the AC power supply 101 is connected upstream of the rectifier circuit 102.

[0026] A heater 311 for heating a heating roller 310 of the fixing device 300 is connected in series to the output side of the rectifier circuit 102. In this embodiment, a halogen heater is used as the heater 311. In the following description, the heater may be referred to as a halogen heater. A coil 103 is connected between the positive terminal of the rectifier circuit 102 and the heater 311, and a switching element 110 made of a FET or the like is connected between the heater 311 and the negative terminal of the rectifier circuit 102.

[0027] Furthermore, a diode 104 is provided, the anode of which is connected between the heater 311 and the switching element 110, and the cathode of which is connected between the rectifier circuit 102 and the coil 103.

[0028] Reference numeral 400 denotes a PWM control unit. The PWM control unit 400 receives an input voltage detection signal S1 from the input voltage detection unit 200, and also receives a temperature detection signal S3 from a temperature detection unit 312 arranged in the vicinity of the heating roller 310 for detecting the temperature of the heating roller 310. Then, based on the received input voltage detection signal S1 and temperature detection signal S3, the PWM control unit 400 outputs a PWM signal S2 for controlling the on / off of the switching element 110 to the switching element 110. The PWM control unit 400 may be configured by the above-mentioned control unit 9, or may be a separate control unit that operates under the command of the control unit 9.

[0029] Next, the operation of the heater control circuit shown in FIG. 2 will be described.

[0030] When AC power supply 101 is supplied, input voltage detection unit 200 detects the voltage value of input voltage Vin and sends input voltage detection signal S1 to PWM control unit 400. Temperature detection unit 312 detects the temperature of heating roller 310 and sends temperature detection signal S3 to PWM control unit 400. Based on input voltage detection signal S1 and temperature detection signal S3, PWM control unit 400 determines the on-duty ratio of PWM signal S2 so that the temperature of heating roller 310 becomes the set temperature for each operation mode such as plain paper printing, thick paper printing, etc., and sends it to switching element 110.

[0031] For example, if the temperature of the heating roller 310 reaches the set temperature and then exceeds the set value, the power input to the halogen heater 311 is reduced by lowering the duty ratio by the duty adjustment value corresponding to each input voltage Vin. Also, if the temperature of the heating roller 310 falls below the set value, the power input to the halogen heater 311 is increased by raising the duty ratio by the duty adjustment value corresponding to each input voltage Vin, and the temperature of the heating roller 310 is controlled to reach the set temperature. An example of the duty adjustment value is shown in the table of FIG. 3. In this example, the duty ratio is configured to be lowered by -0.5% when the temperature of the heating roller 310 exceeds the set temperature, and to be increased by +0.5% when the temperature falls below the set temperature.

[0032] The switching element 110 starts to turn on and off based on the PWM signal S2. When the switching element 110 is turned on, the current supplied from the AC power supply 101 is full-wave rectified by the rectifier circuit 102 and flows to the coil 103 and the halogen heater 311. During this time, the coil 103 stores a part of the current Ihe flowing through it as magnetic energy. On the other hand, when the switching element 110 is turned off, the magnetic energy stored in the coil 103 is released as the current Ihe and starts to flow to the halogen heater 311. This current Ihe returns to the coil 103 via the diode 104. When the current from the coil 103 disappears, the current Ihe flowing to the halogen heater 311 becomes zero until the next on-state operation of the switching element 110, and heating of the halogen heater 311 is interrupted.

[0033] Through the above operations, the halogen heater 311 is supplied with the power required to maintain the set temperature for each operation mode, and the temperature of the heating roller 310 is maintained at the set temperature for each operation mode.

[0034] The upper limit value dutymax of the on-duty ratio determined by the PWM control unit 400 is set to a value corresponding to the upper limit current value Ihemax so that the power Whe of the halogen heater 311 is equal to or less than the upper limit power value Whemax sufficient to fix the toner on the paper, depending on the input voltage Vin detected by the input voltage detection unit 200.

[0035] 4A to 4C show an example of the input voltage Vin, the PWM signal S2, and the current Ihe flowing through the halogen heater 311 in the first embodiment. FIG. 4D shows an enlarged view of a portion of the PWM signal S2 and the current Ihe. When the PWM signal S2 is on, the switching element 110 is on. The current Ihe is limited to an upper limit current value Ihemax or less by limiting the on-duty ratio of the PWM signal S2 to dutymax or less.

[0036] FIG. 5 is a table showing an example of the upper limit current value Ihemax, the upper limit power value Whemax, and the upper limit on-duty ratio dutymax with respect to the input voltage Vin in the first embodiment.

[0037] For example, in 100V commercial power areas such as Japan and North America, the upper limit value dutymax of the on-duty ratio is set according to the input voltage of the 100V commercial power area. When used in Japan, if the input voltage detection unit 200 detects an input voltage Vin=102V, for example, the upper limit value dutymax of the on-duty ratio is set to 73.4%, which corresponds to 100V≦Vin<110V, and the upper limit current value Ihemax is limited to 9.1A. The upper limit power value Whemax is set to 1000W.

[0038] The upper limit value dutymax of the on-duty ratio may be determined by referring to the upper limit value dutymax of the on-duty ratio for the input voltage as shown in the table of Fig. 5, which is stored in advance in the PWM control unit 400, or may be calculated from the following formula. The following formula is an example for the halogen heater 311, and is not limited to this formula. In addition, the upper limit value dutymax may be determined taking into consideration parameters that affect the power, such as the voltage drop from the commercial power supply 101 to the input terminal of the halogen heater 311, the response delay of the switching element 110, and the resistance change of the halogen heater 311.

[0039] dutymax(%)=Whemax(W) / Vin(V) / ((Whemax(W) / Vhetyp(V))×(Vin(V) / Vhetyp(V))^0.54) Where Vhetyp is the rated voltage of the halogen heater.

[0040] As described above, the upper limit value dutymax of the on-duty ratio is switched according to the input voltage Vin of the AC power supply 101 detected by the input voltage detection unit 200, so the timing at which current flows to the halogen heater 311 is determined to be an optimal value according to the input voltage Vin. This operation makes it possible to obtain an appropriate amount of heat for fixing toner even if the input voltage Vin differs depending on the country or region of use, without having to split the heater into two and perform series / parallel switching as described in the conventional Patent Document 1. [Second embodiment] FIG. 6 is a circuit diagram of a heater control circuit according to a second embodiment of the present invention.

[0041] In this heater control circuit, the rectifier circuit 102 and coil 103 of the heater control circuit shown in Fig. 2 are not provided, but the AC power source 101 and halogen heater 311 are connected in series, and AC power from the AC power source 101 is supplied to the halogen heater 311. Also, an input voltage detection unit 200 is provided that detects the input voltage Vin of the AC power source 101, and a bidirectional switching element 120 made of a triac or the like is disposed between the halogen heater 311 and the AC power source 101. The input voltage detection unit 200 also detects zero crossings of the input voltage Vin, and outputs a zero crossing signal S7 indicating the zero crossings.

[0042] Reference numeral 500 denotes a phase control unit. The phase control unit 500 receives the input voltage detection signal S1 and the zero cross signal S7 from the input voltage detection unit 200, and also receives the temperature detection signal S3 from the temperature detection unit 312 disposed near the heating roller 311. Then, based on the received input voltage detection signal S1, the zero cross signal S7, and the temperature detection signal s3, the phase control unit 500 outputs a phase control signal S4 for controlling the ON timing of the switching element 120 to the switching element 120. The phase control unit 500 may be configured by the above-mentioned control unit 9, or may be a separate control unit that operates under the command of the control unit 9.

[0043] Next, the operation of the heater control circuit shown in FIG. 6 will be described.

[0044] When the AC power supply 101 is supplied, the input voltage detection unit 200 detects the voltage value of the input voltage Vin and transmits an input voltage detection signal S1 to the phase control unit 500. The input voltage detection unit 200 also detects the zero crossing of the input voltage Vin and transmits a zero crossing signal S7 to the phase control unit 500. The temperature detection unit 312 detects the temperature of the heating roller 310 and transmits a temperature detection signal S3 to the phase control unit 500.

[0045] Based on the input voltage detection signal S1, the zero-cross signal S7, and the temperature detection signal S3, the phase control unit 500 determines the phase angle, which is the timing to turn on the switching element 120, so that the temperature of the heating roller 310 becomes the set temperature for each operation mode, such as plain paper printing, thick paper printing, etc. Then, the phase control unit 500 transmits a phase control signal S4 to the switching element 120 for each half cycle of the AC power supply 101 so that the switching element 120 is turned on at the determined phase angle.

[0046] The switching element 120 starts an ON operation based on the phase control signal S4. When the switching element 120 is turned ON, the ON state of the switching element 120 is maintained until the zero cross point of the current supplied from the AC power supply 101 is reached, and a current flows through the halogen heater 311 during that time.

[0047] By the above operation, the halogen heater 311 is supplied with the power required to maintain the set temperature for each operation mode, and the temperature of the heating roller 310 is maintained at the set temperature for each operation mode.

[0048] The lower limit value θmin of the on phase angle determined by the phase control unit 500 is set to a value corresponding to the upper limit current value Ihemax so that the power Whe of the halogen heater 311 is equal to or less than the upper limit power value Whemax sufficient to fix the toner on the paper, depending on the input voltage Vin.

[0049] 7A to 7C respectively show examples of the input voltage Vin, the phase control signal S4, and the current Ihe flowing through the halogen heater 311 in the second embodiment. The current Ihe is limited to an upper limit current value Ihemax or less by limiting the on phase angle of the phase control signal S4 to a lower limit value θmin or more.

[0050] FIG. 8 is a table showing an example of the upper limit current value Ihemax, the upper limit power value Whemax, and the lower limit θmin of the on-phase angle with respect to the input voltage Vin in the second embodiment.

[0051] For example, in 100V commercial power supply regions such as Japan and North America, the lower limit θmin of the on-phase angle is set according to the input voltage Vin of the 100V commercial power supply region. When used in Japan, if the input voltage detection unit 200 detects an input voltage Vin=102V, the lower limit θmin of the on-phase angle is set to 107 degrees corresponding to 100V≦Vin<110V, and the upper limit current value Ihemax is limited to 9.1A. The upper limit power value Whemax is set to 1000W.

[0052] The lower limit value θmin of the on-phase angle may be determined by referring to the lower limit value θmin of the on-phase angle with respect to the input voltage as shown in FIG.

[0053] As described above, the lower limit θmin of the on phase angle is switched according to the input voltage Vin of the AC power supply 101 detected by the input voltage detection unit 200, so that the timing at which current flows to the halogen heater 311 is determined to be an optimal value according to the input voltage Vin. This operation makes it possible to obtain an appropriate amount of heat for fixing toner even if the input voltage Vin differs depending on the country or region of use, without dividing the heater into two and switching between series and parallel as described in the conventional Patent Document 1. Moreover, compared to the first embodiment, the rectifier circuit 102, coil 103, and diode 104 are no longer necessary, making it possible to further reduce costs. [Third embodiment] FIG. 9 is a circuit diagram of a heater control circuit according to a third embodiment of the present invention.

[0054] Like the heater control circuit according to the second embodiment shown in Fig. 6, this heater control circuit does not include the rectifier circuit 102, coil 103, or diode 104, but instead has an AC power source 101 and a halogen heater 311 connected in series, and AC power from the AC power source 101 is supplied to the halogen heater 311. Also, an input voltage detection unit 200 is provided that detects the input voltage Vin of the AC power source 101, and a bidirectional switching element 120 is disposed between the halogen heater 311 and the AC power source 101. The input voltage detection unit 200 also detects zero crossings of the input voltage Vin, and outputs a zero crossing signal S7 indicating the zero crossings.

[0055] Reference numeral 600 denotes a half-wave control unit. The half-wave control unit 600 receives the input voltage detection signal S1 and the zero-cross signal S7 from the input voltage detection unit 200, and also receives the temperature detection signal S3 from the temperature detection unit 312 disposed in the vicinity of the heating roller 310. The half-wave control unit 600 outputs a half-wave control signal S5 for controlling the on / off operation of the switching element 120 to the switching element 120 based on the received input voltage detection signal S1, the zero-cross signal S7, and the temperature detection signal S3.

[0056] Specifically, a predetermined period (for example, 20 half waves) is set in advance. The half-wave control unit 600 outputs a half-wave control signal S5 so that a required number of half waves among the half waves of the input voltage Vin from the AC power source 101 are supplied to the halogen heater 311 during one set period in accordance with the input voltage Vin from the AC power source 101. In the following description, the set period is also referred to as a half-wave control period, and the required number of half waves is also referred to as the number of ON half waves. The half-wave control unit 600 may be configured by the above-mentioned control unit 9, or may be a separate control unit that operates under the command of the control unit 9.

[0057] Next, the operation of the heater control circuit shown in FIG. 9 will be described.

[0058] When the AC power supply 101 is supplied, the input voltage detection unit 200 detects the voltage value of the input voltage Vin and transmits an input voltage detection signal S1 to the half-wave control unit 600. The input voltage detection unit 200 also detects the zero crossing of the input voltage Vin and transmits a zero crossing signal S7 to the phase control unit 500. The temperature detection unit 312 detects the temperature of the heating roller 310 and transmits a temperature detection signal S3 to the half-wave control unit 600.

[0059] Based on the input voltage detection signal S1 and the temperature detection signal S3, the half-wave control unit 600 determines the number of on half-waves in a half-wave control cycle so that the temperature of the heating roller 310 becomes the set temperature for each operation mode, such as plain paper printing or thick paper printing, and sends a half-wave control signal S5 to the switching element 120. The switching element 120 starts its on / off operation based on the half-wave control signal S5. When the switching element 120 is turned on, the current supplied from the AC power supply 101 flows to the halogen heater 311 until it reaches the zero-cross point.

[0060] By the above operation, the halogen heater 311 is supplied with the power required to maintain the set temperature for each operation mode, and the temperature of the heating roller 310 is maintained at the set temperature for each operation mode.

[0061] The upper limit value HCmax of the on half-wave number determined by the half-wave control unit 600 is set to a value corresponding to the upper limit current value Ihemax so that the power Whe of the halogen heater 311 is equal to or less than the upper limit power value Whemax sufficient to fix the toner on the paper, depending on the input voltage Vin.

[0062] 10A to 10C show an example of the input voltage Vin, the half-wave control signal S5, and the current Ihe flowing through the halogen heater 311 in the third embodiment. In this example, the half-wave control period is 20 half waves, but is not limited to 20 half waves. The current Ihe is limited to an upper limit current value Ihemax or less by limiting the number of on half waves of the half-wave control signal S5 to an upper limit value or less.

[0063] FIG. 11 is a table showing an example of the upper limit current value Ihemax, the upper limit power value Whemax, and the upper limit value HCmax of the on half wave number with respect to the input voltage Vin in the third embodiment.

[0064] For example, in 100V commercial power areas such as Japan and North America, the upper limit HCmax of the on-half-wave number is set according to the input voltage Vin of the 100V commercial power area. When used in Japan, if the input voltage detection unit 200 detects an input voltage Vin=102V, the upper limit HCmax of the on-half-wave number is set to 15 half-waves corresponding to 100V≦Vin<110V, and the upper limit current value Ihemax is limited to 9.3A. The upper limit power value Whemax is set to 1022W, compared to 1000W, which is sufficient for fixing toner.

[0065] The upper limit HCmax of the on half-wave number may be determined by referring to the upper limit HCmax of the on half-wave number for the input voltage as shown in the table of Fig. 11, which is stored in advance in the half-wave control unit 600, or may be calculated from the following formula. The following formula is an example for the halogen heater 311, and is not limited to this formula. In addition, the upper limit HCmax may be determined taking into consideration parameters that affect the power, such as the voltage drop from the commercial power source 101 to the heater input terminal, the response delay of the switching element 120, and the resistance change of the halogen heater 311.

[0066] HCmax(half wave) = half wave control period (20 half waves) / (Vin / Vhetyp)^1.54 Where Vhetyp is the rated voltage of the halogen heater.

[0067] As described above, the upper limit value HCmax of the on-half wave number is switched according to the input voltage Vin of the AC power source 101 detected by the input voltage detection unit 200, so that the timing at which the current flows to the halogen heater 311 is determined to be an optimal value according to the input voltage Vin. This operation makes it possible to obtain an appropriate amount of heat for fixing the toner even if the input voltage Vin differs depending on the country or region of use, without dividing the heater into two and switching between series and parallel as described in the conventional Patent Document 1. Furthermore, unlike the second embodiment, there is no waveform distortion of the current Ihe flowing through the halogen heater 311, and the waveform is sinusoidal, so that deterioration of the power factor can be avoided. Moreover, compared to the first embodiment, the rectifier circuit 102, the coil 103, and the diode 104 are not necessary, which allows further cost reduction. [Fourth embodiment] FIG. 12 is a circuit diagram of a heater control circuit according to a fourth embodiment of the present invention.

[0068] 2 in that a GPS (Global Positioning System) 700 (corresponding to a reception unit) capable of acquiring location information is provided instead of the input voltage detection unit 200. The PWM control unit 400 receives a location information signal S6 acquired by the GPS 700 and a temperature detection signal S3 from the temperature detection unit 312, and transmits a PWM signal S2 to the switching element 110.

[0069] Specifically, the PWM control unit 400 receives the location information signal S6 acquired by the GPS 700, determines the area where the image forming apparatus 1 is installed, and identifies the input voltage Vin of the AC power supply in that area. Based on the identified input voltage Vin and the temperature detection signal S3 received from the temperature detection unit 312, the PWM control unit 400 determines the on-duty ratio of the PWM signal S2 so that the temperature of the heating roller 310 becomes the set temperature for each operation mode such as plain paper printing, thick paper printing, etc. Then, the PWM signal S2 with the determined on-duty ratio is transmitted to the switching element 110.

[0070] The operation of the heater control circuit after the PWM signal S2 is transmitted to the switching element 110 is similar to that of the first embodiment of FIG.

[0071] The upper limit value dutymax of the on-duty ratio determined by the PWM control unit 400 is set to a value corresponding to the upper limit current value Ihemax so that the power Whe of the halogen heater 311 is equal to or less than the upper limit power Whemax sufficient to fix the toner on the paper, in accordance with the input voltage Vin determined based on the position information signal S6 acquired by the GPS 700.

[0072] FIG. 13 is a table showing an example of the upper limit current value Ihemax, the upper limit power value Whemax, and the upper limit on-duty ratio dutymax with respect to the input voltage Vin in each target area in the fourth embodiment.

[0073] For example, when the region is determined to be Japan, the input voltage Vin=100V is specified, and the upper limit dutymax of the on-duty ratio corresponding to Vin=100V is set to 85%. The upper limit power value Whemax is set to 1000W.

[0074] The upper limit value dutymax of the on-duty ratio may be determined by referring to the upper limit value of the on-duty ratio for the input voltage Vin as shown in the table of Fig. 13, which is stored in advance in the PWM control unit 400, or may be calculated from the following formula. The following formula is an example for the halogen heater 311, and is not limited to this formula. In addition, the upper limit value dutymax may be determined taking into consideration parameters that affect the power, such as the voltage drop from the commercial power supply 101 to the heater input terminal, the response delay of the switching element 110, and the resistance change of the halogen heater 311.

[0075] dutymax(%)=Whemax(W) / Vin(V) / ((Whemax(W) / Vhetyp(V))×(Vin(V) / Vhetyp(V))^0.54) where Vhetyp is the rated voltage of the halogen heater.

[0076] As described above, the upper limit value dutymax of the on-duty ratio is switched according to the input voltage Vin of the AC power supply 101 specified based on the position information acquired by the GPS 700, so the timing at which current flows to the halogen heater 311 is determined to be an optimal value according to the input voltage Vin. This operation makes it possible to obtain an appropriate amount of heat for fixing toner even if the input voltage Vin differs depending on the country or region of use, without having to split the heater into two and perform series / parallel switching as described in the conventional Patent Document 1. [Fifth embodiment] FIG. 14 is a circuit diagram of a heater control circuit according to a fifth embodiment of the present invention.

[0077] This embodiment differs from the heater control circuit according to the second embodiment shown in Fig. 5 in that it includes a GPS 700 capable of acquiring position information similar to the heater control circuit shown in Fig. 12 and a zero-cross detection unit 105 instead of the input voltage detection unit 200. The zero-cross detection unit 105 detects zero crosses of the input voltage Vin and outputs a zero-cross signal S7.

[0078] The phase control unit 500 receives a position information signal S6 acquired by the GPS 700, a zero cross signal S7 from the zero cross detection unit 105, and a temperature detection signal S3 from the temperature detection unit 312, and transmits a phase control signal S2 to the switching element SW3.

[0079] Specifically, the phase control unit 500 receives a location information signal S6 acquired by the GPS 700, determines the area where the image forming apparatus 1 is installed, and identifies the input voltage Vin of the AC power source in that area. Based on the identified input voltage Vin and the temperature detection signal S3 received from the temperature detection unit 312, the phase control unit 500 determines the on phase angle, which is the timing to turn on the switching element 120, so that the temperature of the heating roller 310 becomes the set temperature in each operation mode such as plain paper printing, thick paper printing, etc. Then, based on the zero cross signal S7 from the zero cross detection unit 105, the phase control signal S4 is transmitted to the switching element 120 for each half cycle of the AC power source 101 so that the switching element 120 is turned on at the determined phase angle.

[0080] The operation of the heater control circuit after the phase control signal S4 is sent to the switching element 120 is similar to that of the second embodiment of FIG.

[0081] The lower limit value θmin of the on phase angle determined by the phase control unit 500 is set to a value corresponding to the upper limit current value Ihemax so that the power Whe of the halogen heater 311 is equal to or less than the upper limit power value Whemax sufficient to fix the toner on the paper, in accordance with the input voltage Vin determined based on the position information signal S6 acquired by the GPS 700.

[0082] FIG. 15 is a table showing an example of the upper limit current value Ihemax, the upper limit power value Whemax, and the lower limit value θmin of the on-phase angle with respect to the input voltage Vin in each target area in the fifth embodiment.

[0083] For example, when the region is determined to be Japan, the input voltage Vin=100V is specified, and the lower limit θmin of the on phase angle corresponding to Vin=100V is set to 85 degrees. The upper limit power value Whemax is set to 1000W.

[0084] The lower limit value θmin of the ON phase angle may be determined by referring to the lower limit values ​​of the ON phase angle as shown in the table of FIG.

[0085] As described above, the lower limit θmin of the on phase angle is switched according to the input voltage Vin of the AC power supply 101 specified based on the position information acquired by the GPS 700, so the timing at which current flows to the halogen heater 311 is determined to be an optimal value according to the input voltage Vin. This operation makes it possible to obtain an appropriate amount of heat for fixing toner even if the input voltage Vin differs depending on the country or region of use, without having to divide the heater into two and perform series / parallel switching as described in the conventional Patent Document 1. [Sixth embodiment] FIG. 16 is a circuit diagram of a heater control circuit according to the sixth embodiment of the present invention.

[0086] This embodiment differs from the heater control circuit according to the second embodiment shown in Fig. 6 in that it includes a GPS 700 and a zero-cross detection unit 105 capable of acquiring position information similar to the heater control circuit shown in Fig. 12, instead of the input voltage detection unit 200. The half-wave control unit 600 receives a position information signal S6 acquired by the GPS 700, a zero-cross signal S7 from the zero-cross detection unit 105, and a temperature detection signal S3 from the temperature detection unit 312, and transmits a PWM signal S2 to the switching element 120.

[0087] The half-wave control unit 600 receives the location information signal S6 acquired by the GPS 700, determines the area where the image forming apparatus 1 is installed, and identifies the input voltage Vin of the AC power supply in that area. Based on the identified input voltage Vin and the temperature detection signal S3 received from the temperature detection unit 312, the half-wave control unit 600 determines the number of ON half waves in the half-wave control cycle so that the temperature of the heating roller 311 becomes the set temperature for each operation mode such as plain paper printing, thick paper printing, etc. Then, based on the zero-cross detection signal S10 received from the zero-cross detection unit, it transmits a half-wave control signal S5 to the switching element SW4 so that the number of ON half waves becomes the determined number.

[0088] The operation of the heater control circuit after the half-wave control signal S5 is sent to the switching element 120 is similar to that of the third embodiment of FIG.

[0089] The upper limit value HCmax of the on half-wave number determined by the half-wave control unit 600 is set to a value corresponding to the upper limit current value Ihemax so that the power Whe of the halogen heater 311 is equal to or less than the upper limit power value Whemax sufficient to fix the toner on the paper, depending on the input voltage Vin.

[0090] FIG. 16 is a table showing an example of the upper limit current value Ihemax, the upper limit power value Whemax, and the upper limit value HCmax of the on half wave number with respect to the input voltage Vin in each target area in the sixth embodiment.

[0091] For example, when the region is determined to be Japan, the upper limit HCmax of the ON half-wave number corresponding to the Japanese input voltage Vin=100V is set to 18 half-waves. The upper limit power value Whemax is set to 1059 W, which is larger than 1000 W sufficient for fixing toner. The upper limit HCmax of the ON half-wave number may be determined by referring to the upper limit HCmax of the ON half-wave number for the input voltage as shown in the table of FIG. 17, which is stored in advance in the half-wave control unit 600, or may be calculated from the following formula. The following formula is an example for the halogen heater 311, and is not limited to this formula. In addition, parameters that affect the power, such as the voltage drop from the commercial power source 101 to the heater input terminal, the response delay of the switching element 120, and the resistance change of the halogen heater 311, may be taken into consideration.

[0092] HCmax(half wave) = half wave control period (20 half waves) / (Vin / Vhetyp)^1.54 Where Vhetyp is the rated voltage of the halogen heater.

[0093] By the above operation, it is possible to obtain an appropriate amount of heat for fixing the toner regardless of the input voltage Vin, without providing the input voltage detection unit 200. [Seventh embodiment] In this embodiment, the regions where the input voltage Vin is used are classified into two types, 100V commercial power supply regions and 200V commercial power supply regions, and settings are made according to each type.

[0094] The configuration of the heater control circuit is the same as that of the first embodiment shown in Fig. 2. The on-duty ratio of the PWM signal S2 is limited to be equal to or less than dutymax, thereby limiting the current Ihe to be equal to or less than the upper limit current value Ihemax.

[0095] FIG. 18 is a table showing an example of the upper limit current value Ihemax, the upper limit power value Whemax, and the upper limit on-duty ratio dutymax with respect to the input voltage Vin in each target area in the seventh embodiment.

[0096] When the input voltage detection unit 200 detects an input voltage Vin (100V≦Vin≦120V) of a 100V commercial power source region such as Japan or North America, it sets the upper limit value of the on-duty ratio dutymax=100% corresponding to that region. When the input voltage detection unit 200 detects an input voltage Vin (220V≦Vin≦240V) of a 200V commercial power source region such as Europe or China, it sets the upper limit value of the on-duty ratio dutymax=29.7% corresponding to that region.

[0097] The upper limit power value Whemax is set at 1000W, which is sufficient for fixing the toner, but is set at 1324W in areas with 100V commercial power supply and 1143W in areas with 200V commercial power supply.

[0098] In this embodiment, the heater control circuit has the same configuration as that of the first embodiment. However, the heater control circuit may have the same configuration as that of the second or third embodiment, and the lower limit θmin of the on-phase angle and the upper limit HCmax of the on-half wave number may be set for the 100V commercial power supply area and the 200V commercial power supply area. Also, the heater control circuit may have a configuration including a GPS 700 as in the fourth, fifth, or sixth embodiment, and the upper limit dutymax of the on-duty, the lower limit θmin of the on-phase angle, and the upper limit HCmax of the on-half wave number may be set for the 100V commercial power supply area and the 200V commercial power supply area.

[0099] With the above operations, the settings for 100V commercial power supply areas and 200V commercial power supply areas can be consolidated into one for the first to sixth embodiments, respectively, and the processes for determining the upper limit value dutymax of the on-duty ratio, the lower limit value θmin of the on-phase angle, and the upper limit value HCmax of the on-half wave number can be simplified.

[0100] Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments. For example, in the first embodiment, when the temperature of the heating roller 310 exceeds or falls below the set temperature, the duty ratio is adjusted by the duty adjustment value shown in Fig. 3. However, the duty adjustment when the temperature of the heating roller 310 exceeds or falls below the set temperature may be performed in the same manner in the second to seventh embodiments. [Explanation of symbols]

[0101] 1. Image forming device 3. Image forming section 9. Control Unit 10 Power circuit 101 AC power supply (commercial power supply) 102 Rectifier circuit 103 Coil 104 Diode 105 Zero cross detection unit 110, 120 Switching element 200 Input voltage detection unit (reception unit) 300 Fixing unit 310 Heating roller 311 Heater (Halogen heater) 312 Temperature detection unit 320 Pressure Roller 400 PWM control unit 500 Phase control section 600 Half-wave control section 700 GPS (Reception)

Claims

1. A heating unit; A reception unit that receives a plurality of types of input voltages; a determination unit that determines a timing at which a current flows to the heating unit in response to the input voltage received by the reception unit; An image forming apparatus comprising:

2. 2. The image forming apparatus according to claim 1, further comprising a voltage detection means for detecting an input voltage, and determining a timing for causing a current to flow to said heating portion in response to a detection result of said voltage detection means.

3. 3. The image forming apparatus according to claim 1, further comprising a temperature detection means for detecting a temperature of the heating portion, and determining a timing for causing a current to flow to the heating portion in accordance with a detection result of the voltage detection means and a detection result of the temperature detection means.

4. 3. The image forming apparatus according to claim 1, wherein an upper limit value of the current flowing through said heating portion is changed depending on a type of input voltage.

5. 3. The image forming apparatus according to claim 1, wherein when the input voltage is relatively low, the upper limit of the current flowing through the heating unit is set higher than when the input voltage is relatively high.

6. 3. The image forming apparatus according to claim 1, wherein an upper limit of the current flowing through the heating section is set to a value at which the power of the heating section is equal to or lower than a predetermined value.

7. A control means is provided for controlling the current flowing through the heating unit by PWM control, 3. The image forming apparatus according to claim 1, wherein the control means switches the current by changing a PWM duty ratio within a half cycle of the input current.

8. A control means for phase-controlling a current flowing in the heating section is provided, 3. The image forming apparatus according to claim 1, wherein the control means switches the current by changing a conduction angle to the heating means.

9. 3. The image forming apparatus according to claim 1, wherein the current flowing through the heating section is switched by turning the current on and off in units of a half cycle of an input voltage.

10. An acquisition unit for acquiring information about an area where the image forming apparatus is installed and determining the area, 3. The image forming apparatus according to claim 1, wherein an upper limit of the current flowing to the heating unit is set to a value corresponding to the region determined by the acquisition unit.

11. An image forming apparatus including a heating unit, a receiving step of receiving a plurality of types of input voltages; a determination step of determining a timing at which a current flows to the heating unit in response to the input voltage received in the receiving step; A heating method comprising the steps of:

12. A computer of an image forming apparatus having a heating unit a receiving step of receiving a plurality of types of input voltages; a determination step of determining a timing at which a current flows to the heating unit in response to the input voltage received in the receiving step; A program for executing the above.

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