Image forming apparatus

Abstract

This method shortens the WUT (Write-Through Time) while suppressing condensation on the photosensitive drum. [Solution] The image forming apparatus comprises an image forming unit (3) for forming an image on a recording material, an environmental heater 311 for adjusting the temperature of the image forming unit (3), and a control unit 14 that supplies a first amount of power to the environmental heater 311 in a first state, a second amount of power smaller than the first amount of power to the environmental heater 311 in a second state, and stops supplying power to the environmental heater 311 in a third state.

Description

Technical Field

[0001] The present invention relates to an image forming apparatus that forms an image on a recording material.

Background Art

[0002] In recent years, image forming apparatuses are expected to be free from condensation. Among image forming apparatuses, there is an image forming apparatus that fixes an image on a recording material by heating and melting a toner image formed on the recording material with a fixing device. Since such an image forming apparatus includes a portion that operates at a high temperature, the problem of condensation is particularly prominent. In response to this, Patent Document 1 discloses an image forming apparatus provided with an environmental heater for raising the temperature around a photosensitive drum.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0004] Incidentally, it is preferable that the first copy output time (hereinafter referred to as "FCOT"), which is the time taken until a printed matter is output from the image forming apparatus, is shortened. The FCOT includes an adjustment time, and the adjustment time is dominated by the warm-up time (hereinafter referred to as "WUT") during which the temperature of the fixing device is preheated to a temperature at which the toner image can be fixed. Therefore, in order to shorten the WUT, it is desirable to supply power to the fixing device as much as possible during warm-up (hereinafter referred to as "WU").

[0005] In this configuration, as in the image forming apparatus described in Patent Document 1, an ambient heater is used to raise the ambient temperature around the photosensitive drum. During the WU (Wake-Up Time) phase, the ambient heater consumes power. Generally, the maximum power supplied to an image forming apparatus is often limited by the outlet rating. Therefore, supplying power to the ambient heater can lead to a decrease in the amount of power supplied to the fuser. As a result, shortening the WUT (Wake-Up Time) phase can become difficult. [Means for solving the problem]

[0006] The image forming apparatus of the present invention comprises: an image forming means for forming an image on a recording material; a heat source for adjusting the temperature of the image forming means; and a control means for supplying a first amount of power to the heat source in a first state, supplying a second amount of power smaller than the first amount of power to the heat source in a second state, and stopping the supply of power to the heat source in a third state. [Effects of the Invention]

[0007] According to the present invention, it is possible to reduce power consumption while shortening the warm-up time of the image forming apparatus. [Brief explanation of the drawing]

[0008] [Figure 1] Internal diagram of the printer. [Figure 2] Block diagram of a printer. [Figure 3] Diagram illustrating the configuration of the temperature control controller. [Figure 4] A diagram illustrating the time evolution of conventional current consumption, surface temperature, and power consumption. [Figure 5] A diagram illustrating the time evolution of current consumption, surface temperature, and power consumption in the first embodiment. [Figure 6] A table showing commercial power supply voltage and environmental heater power consumption by country. [Figure 7] A flowchart illustrating the process from acquiring a print job to ejecting the printed document. [Figure 8] A flowchart illustrating the power control of an environmental heater. [Figure 9] Diagram illustrating the configuration of the control unit according to the second embodiment. [Figure 10] A flowchart illustrating the power control of the environmental heater in the second embodiment. [Figure 11] Internal configuration diagram of the printer according to the third embodiment. [Figure 12] A diagram illustrating the configuration of the temperature control controller according to the third embodiment. [Figure 13] A diagram illustrating the time evolution of current consumption, surface temperature, and power consumption in the third embodiment. [Figure 14] A flowchart illustrating the power control of the environmental heater in the third embodiment. [Modes for carrying out the invention]

[0009] Preferred embodiments of the present invention will be described below with reference to the attached drawings. While the following description will focus on an example of applying the present invention to a monochrome image forming apparatus using an electrophotographic method, the present invention is not limited to this and can be applied to various types of image forming apparatuses, including full-color electrophotographic image forming apparatuses having multiple photosensitive drums.

[0010] Electrophotographic image forming apparatuses fix an image to a recording material by heating and melting a toner image formed on the recording material using a fuser. In such an apparatus, for example, a toner image is formed on the surface of a photosensitive drum, which is a drum-shaped photoreceptor, and this toner image is transferred to the recording material. Condensation may occur on the surface of the photosensitive drum due to environmental changes such as a decrease in temperature or an increase in humidity. When condensation occurs on a photosensitive drum, the toner image cannot be formed stably, which can result in an image defect called "image flow."

[0011] In an image forming apparatus, there are two types of dew condensation: dew condensation during stoppage and dew condensation during sheet passing. Dew condensation during stoppage occurs when the image forming apparatus is in a standby state where it is not performing adjustment or image formation, a sleep state, or a plug-in state where the power plug is inserted into the outlet with the power off. Since the image forming apparatus is not operating, the temperature of the photosensitive drum decreases. As the temperature of the photosensitive drum decreases and the relative humidity rises, moisture adheres to the surface of the photosensitive drum, causing dew condensation. Dew condensation during sheet passing occurs while the image forming apparatus is in a state of image quality adjustment or image formation. Dew condensation during sheet passing is caused by discharge products. Discharge products are generated on the surface of the photosensitive drum during image quality adjustment or image formation. Dew condensation occurs when moisture adheres to the discharge products. Image blurring occurs when image formation is performed in a state where moisture has adhered to the discharge products.

[0012] As a countermeasure against such dew condensation, the image forming apparatus of the present embodiment raises the ambient temperature around the photosensitive drum using an environmental heater. By increasing the ambient temperature around the photosensitive drum with the environmental heater, the relative humidity is lowered, and the occurrence of dew condensation is suppressed.

[0013] (First Embodiment) Figure 1 is an internal configuration diagram of a printer which is the image forming apparatus of the present embodiment. Figure 2 is a block diagram of the printer 1. The printer 1 includes a plurality of sheet feeding cassettes 2, an image forming unit 3, a discharge tray 4, a sheet conveying mechanism 5, an operation unit 6, and a main switch 10.

[0014] The plurality of sheet feeding cassettes 2 can each store recording materials of different sizes. The image forming unit 3 forms an image on the recording material conveyed from the sheet feeding cassette 2. The recording material on which an image has been formed by the image forming unit 3 is discharged to the discharge tray 4. The sheet conveying mechanism 5 conveys the recording material. The operation unit 6 receives operation instructions from a user. The main switch 10 can switch the power state of the printer 1 in response to a user operation.

[0015] The sheet conveyance mechanism 5 includes a paper feed roller 51, a conveyance roller 52, a discharge roller 53, and the like. The paper feed roller 51 feeds recording materials one by one from the paper feed cassette 2 and conveys them toward the image forming unit 3. The conveyance roller 52 conveys the recording material fed by the paper feed roller 51 into the image forming unit 3. The conveyance roller 52 may be a registration roller that corrects skew feeding of the recording material. The discharge roller 53 discharges the recording material conveyed from the image forming unit 3 to the discharge tray 4.

[0016] The operation unit 6 is a user interface having an input interface and an output interface. As the output interface, the operation unit 6 includes a display 61 composed of a liquid crystal display or the like that displays operation guides and the like for the user. As the input interface, the operation unit 6 includes a key switch 62 that receives operation instructions for the user to select the operation guide display shown on the display 61 and input data such as setting values.

[0017] The image forming unit 3 includes a photosensitive drum 31, a charger 32, an exposure device 33, a developing device 34, a transfer unit 35, and a fixing device 36. The photosensitive drum 31 is a drum-shaped photoreceptor having a photosensitive layer on its surface, and rotates in the direction of the arrow in Fig. 1. The photosensitive drum 31 functions as an image carrier. The charger 32 uniformly charges the surface of the photosensitive drum 31. The exposure device 33 outputs laser light modulated based on image data, and exposes the charged surface of the photosensitive drum 31. An electrostatic latent image is formed on the surface of the photosensitive drum 31 by exposure. The developing device 34 develops the electrostatic latent image formed on the surface of the photosensitive drum 31 with toner, and forms a toner image on the surface of the photosensitive drum 31.

[0018] The transfer unit 35 transfers the toner image formed on the surface of the photosensitive drum 31 to the recording material conveyed by the sheet conveyance mechanism 5. The transfer unit 35 conveys the recording material onto which the toner image has been transferred to the fixing device 36. The fixing device 36 heats the recording material onto which the toner image has been transferred to melt the toner, thereby fixing the toner image on the recording material.

[0019] The printer 1 is equipped with an environmental sensor 360 located below the paper feed cassette 2 for detecting environmental conditions such as ambient temperature and humidity at the printer 1's installation location. The printer 1 is equipped with an environmental heater 311 on the photosensitive drum 31. The environmental heater 311 is a heat source for heating the photosensitive drum 31 to adjust its temperature. The environmental heater 311 is planar and is installed inside the photosensitive drum 31.

[0020] Printer 1 is equipped with a CPU (Central Processing Unit) 8 and a communication interface (I / F) 7. The communication I / F 7 communicates with a PC (Personal Computer) 9, which is connected via a cable or the like to enable data transmission and reception. The CPU 8 transmits and receives print data and printer control commands, which are operation instructions for image formation, to the PC 9 via the communication I / F 7. The image forming unit 3, environmental sensor 360, operation unit 6, and paper transport mechanism 5 are connected to the CPU 8.

[0021] The CPU 8 generates control signals to control the operation of various parts such as the image forming unit 3 and the paper transport mechanism 5 in accordance with the print data and printer control commands acquired from the PC 9, thereby controlling the image forming operation. Instructions for image forming operations can also be given to the CPU 8 from the operation unit 6.

[0022] CPU 8 is the main control unit that controls the overall operation of printer 1. CPU 8 controls the operation of printer 1 by executing a control program for printer 1 stored, for example, in ROM (Read Only Memory) (not shown). In this case, the control program is loaded into RAM (Random Access Memory) (not shown). RAM provides a work area for temporary data storage when CPU 8 executes processing.

[0023] In addition to the above configuration, the image forming unit 3 also has a temperature sensor 312. Power is supplied to the ambient heater 311 under the control of the CPU 8, causing the surface temperature of the entire photosensitive drum 31 to rise. The temperature sensor 312 is a temperature detection unit that detects the surface temperature of the photosensitive drum 31. The temperature sensor 312 is composed of, for example, a non-contact thermopile or a thermistor. The CPU 8 can detect the surface temperature of the photosensitive drum 31 based on the detection result from the temperature sensor 312. The CPU 8 can also detect the ambient temperature and ambient humidity of the printer 1 based on the detection result from the ambient sensor 360.

[0024] When the CPU 8 is in standby mode and there are no jobs such as print data or printer control commands, it adjusts the temperature of the fuser 36 to prevent it from falling below a predetermined temperature. Furthermore, after a predetermined time has elapsed in standby mode, the CPU 8 cuts off power to unnecessary loads and transitions from standby mode to sleep mode. In sleep mode, the temperature of the fuser 36 is not adjusted. When the main switch is turned off by user operation, power to the CPU 8 is cut off, and the printer 1 enters a plugged-in state, as if its power plug were inserted into an outlet.

[0025] When CPU 8 acquires a job while in standby or sleep mode, it goes through a warm-up (WU) phase before entering an image formation state where image formation operations can be performed. During the WU phase, the fuser unit 36 ​​is heated to a fixing temperature at which toner images can be fixed.

[0026] Figure 3 is a diagram illustrating the configuration of a temperature control controller that adjusts the temperature of the environmental heater 311. The temperature control controller consists of a CPU 8 and a control unit 14 that includes the environmental heater 311. The printer 1 is equipped with power connection terminals 11 and 12. A commercial power supply 13 is connected between the power connection terminals 11 and 12. The state in which the commercial power supply 13 and the power connection terminals 11 and 12 are connected is equivalent to the state in which the power plug is inserted into an outlet.

[0027] The control unit 14 includes, in addition to the environmental heater 311, a triac 314, a phototriac coupler 315, an amplifier 317, a set temperature unit 318, and a comparator 319. The environmental heater 311 and the triac 314 are connected between power connection terminals 11 and 12. The gate of the triac 314 is connected to the output terminal of the comparator 319 via the phototriac coupler 315.

[0028] The inputs to the comparator 319 are a setting temperature unit 318, which outputs a reference voltage corresponding to the set temperature, and an amplifier 317. A temperature sensor 312 is connected to the amplifier 317. The temperature sensor 312 detects the surface temperature of the photosensitive drum 31 and outputs a voltage corresponding to the detected temperature. The setting temperature unit 318 is composed of multiple resistors. The reference voltage is determined by selecting a resistance constant for each resistor that matches the temperature characteristics of the temperature sensor 312. In this embodiment, the setting temperature unit 318 has a hysteresis characteristic in the reference voltage.

[0029] The comparator 319 compares the output voltage of the amplifier 317 (corresponding to the detected temperature) with the output voltage of the set temperature unit 318 (corresponding to the set temperature). In this embodiment, if the output voltage of the set temperature unit 318 is higher than the output voltage of the amplifier 317, the output of the comparator 319 becomes high level. Conversely, if it is lower, the output of the comparator 319 becomes low level.

[0030] The phototriac coupler 315 turns on the triac 314 and lights up (energizes) the ambient heater 311 when the output voltage of the comparator 319 is high. The ambient heater 311 generates heat when energized. Conversely, when the output voltage of the comparator 319 is low, the phototriac coupler 315 turns off the triac 314 and turns off (de-energizes) the ambient heater 311. The ambient heater 311 stops generating heat when de-energized. In other words, the control unit 14 is configured to detect the temperature with the temperature sensor 312 without going through the CPU 8 and control the ambient heater 311 so that the temperature is within a specified range.

[0031] The CPU 8 has a table storage unit 83. The CPU 8 is connected to the base of transistor 320. Transistor 320 is common emitter with its collector connected to the output terminal of comparator 319.

[0032] When CPU8 inputs a high-level signal to transistor 320, transistor 320 turns on, and the output voltage of comparator 319 becomes low. This turns off the ambient heater 311. Conversely, when the output voltage of comparator 319 is high, and CPU8 inputs a low-level signal to transistor 320, transistor 320 turns off. In this case, the output voltage of comparator 319 remains high and is input to phototriac coupler 315. This turns on the ambient heater 311. Also, when the output voltage of comparator 319 is low, and CPU8 inputs a low-level signal to transistor 320, the output voltage of comparator 319 remains low and is input to phototriac coupler 315. This turns off the ambient heater 311.

[0033] The environmental sensor 360 outputs a voltage corresponding to the detected ambient temperature and humidity. The output voltage from the environmental sensor 360 is input to the A / D converter 370 via the amplifier 369. The A / D converter 370 converts the output voltage from the environmental sensor 360, which is input from the amplifier 369, into a digital signal using analog-to-digital conversion, and then inputs it to the CPU 8. The CPU 8 uses the digital signal obtained from the A / D converter 370 to detect the ambient temperature and humidity of the environment in which the printer 1 is installed, and can calculate the amount of moisture in the air.

[0034] When the detected moisture level is lower than a predetermined level, the CPU 8 inputs a high-level signal to the transistor 320 to turn off the environmental heater 311, because the risk of condensation occurring on the surface of the photosensitive drum 31 is low. When the detected moisture level is higher than a predetermined level, the CPU 8 turns on the environmental heater 311, because the risk of condensation occurring on the surface of the photosensitive drum 31 is high.

[0035] A destination detection unit 501 is provided between power connection terminals 11 and 12 to detect the voltage (AC voltage) of the commercial power supply 13. The destination detection unit 501 outputs a voltage corresponding to the detected voltage. The destination detection unit 501 determines the voltage of the commercial power supply 13. The destination detection unit 501 is composed of, for example, a voltage transformer, an A / D converter, etc. The output voltage from the destination detection unit 501 is input to the A / D converter 506 via an amplifier 505. The A / D converter 506 converts the output voltage input from the amplifier 505 into a digital signal by analog-to-digital conversion and inputs it to the CPU 8. As a result, the CPU 8 can detect the voltage of the commercial power supply 13.

[0036] AC / DC power supplies 502 and 504 are connected between power connection terminals 11 and 12. AC / DC power supplies 502 and 504 each convert the AC voltage of the commercial power supply 13 into DC voltage used for the operation of various parts of the printer 1. A relay switch 503 is connected between AC / DC power supply 502 and power connection terminal 12. The conduction state of relay switch 503 is controlled by the operation of the main switch 10.

[0037] The AC / DC power supply 504 is a nighttime power supply and is connected to the commercial power supply 13 via power connection terminals 11 and 12. When the AC / DC power supply 504 is plugged in (with the power plug inserted into the outlet), it outputs a voltage Vr, which is a DC voltage converted from the AC voltage, even when the main switch 10 is off.

[0038] The AC / DC power supply 502 is an emergency night power supply, and unless the main switch 10 is turned ON, the relay switch 503 will not conduct and will not output voltage Vc, which is a DC voltage converted from AC voltage. When the main switch 10 is turned ON, voltage Vr is applied to the relay switch 503 via the main switch 10, causing the relay switch 503 to conduct. As a result, the AC / DC power supply 502 conducts to the commercial power supply 13 and can output voltage Vc.

[0039] Each part of printer 1 is supplied with either voltage Vr or voltage Vc, output from AC / DC power supplies 502 and 504. Because AC / DC power supply 502 is an emergency night power supply, components supplied with voltage Vc will not operate unless the main switch 10 is in the ON position. Because AC / DC power supply 504 is a normal night power supply, components supplied with voltage Vr will operate regardless of the state of the main switch 10. Hereafter, voltage Vc will be referred to as "emergency night voltage Vc" and voltage Vr as "normal night voltage Vr".

[0040] The control unit 14 operates at a normal night voltage Vr. For this reason, the control unit 14 can adjust the ambient heater 311 so that the surface temperature of the photosensitive drum 31 remains within a specified range, even when the CPU 8 is in a sleep state where it is not normally operating, or when the main switch 10 is turned off and the unit is plugged in.

[0041] When CPU8 receives a print job from PC9 via communication interface 7 while in sleep mode, it transitions to standby mode and then controls the image formation operation. During sleep mode, power is supplied only to communication interface 7 and CPU8.

[0042] The plug-in state is when the main switch 10 is in the off state and the commercial power supply 13 is connected to the power connection terminals 11 and 12. In the plug-in state, power is not supplied to anything other than the control unit 14, which operates at the night voltage Vr, and the environmental heater 311, which is directly connected to the commercial power supply 13.

[0043] The CPU 8, destination detection unit 501, amplifiers 369 and 505, and A / D converters 370 and 506 are powered by an emergency night power supply Vc and become unpowered when the main switch 10 is turned off. The table storage unit 83 of the CPU 8 stores the setting values ​​for temperature control of the environmental heater 311, which will be described later, as a table. The table storage unit 83 is provided in RAM or ROM.

[0044] Figure 4 is an explanatory diagram illustrating the time evolution of the current consumption of a conventional printer 1, the surface temperature of the photosensitive drum 31, and the power consumption of the environmental heater 311. Figure 4 shows the sequence of image formation transitions from 450A in standby mode to 451A in wake-up mode, 452A in image formation mode, and then back to 453A in standby mode. Furthermore, Figure 4 shows the transition from 453A in standby mode to 454A in sleep mode after a predetermined time has elapsed, and then to 455A in plug-in mode when the main switch 10 is turned off.

[0045] The environmental heater 311 has an upper limit temperature 401 of 44 degrees Celsius and a lower limit temperature 402 of 38 degrees Celsius set for the time-dependent surface temperature change 403A of the photosensitive drum 31. The upper limit temperature 401 and the lower limit temperature 402 are obtained by converting two reference voltages generated by the temperature setting section 318, which has hysteresis characteristics, into temperature values.

[0046] The control unit 14 turns on the ambient heater 311 when the temperature falls below the lower limit temperature 402 and turns it off when it exceeds the upper limit temperature 401. The control unit 14 compares the output voltage output from the set temperature unit 318 with the output voltage of the amplifier 317 using a comparator 319, and controls the lighting of the ambient heater 311 using a phototriac coupler 315 and a triac 314 according to the comparison result. As a result, the ambient heater 311 turns on when the temperature falls below the lower limit temperature 402 and turns off when it exceeds the upper limit temperature 401. The CPU 8 calculates the amount of moisture from the detection result of the ambient sensor 360, and when the amount of moisture falls below a predetermined value, the transistor 320 stops the temperature control operation of the control unit 14.

[0047] The power consumption of the environmental heater 311 during on and off states is represented by a time-based change of 412A. The environmental heater 311 is supplied with power intermittently at predetermined intervals of 0[W] and 80[W]. During the standby period 440A, 443A, the sleep period 444A, and the plug-in period 445A, the control unit 14 adjusts the temperature of the environmental heater 311. The overall current consumption of the printer 1 is represented by a time-based change of 423A. During the WU period 441A and the image forming period 442A, the overall current consumption of the printer 1 is high, and the current consumption is controlled to keep it within the outlet rating 421.

[0048] During the WU period 441A and the image forming period 442A, the ambient heater 311 is controlled by the control unit 14, without going through the CPU 8, to adjust the temperature by repeatedly turning on and off in accordance with the temperature change over time 403A. In order to keep the power consumption within the outlet rating 421, 80[W] of power is reserved for temperature adjustment of the ambient heater 311, and the remaining power is allocated as the maximum usage limit 422A for the printer 1, including the fuser 36. The above describes the time change in the current consumption of the printer 1, including the ambient heater 311, in the conventional configuration.

[0049] Figure 5 is an explanatory diagram illustrating the time evolution of the current consumption of the printer 1, the surface temperature of the photosensitive drum 31, and the power consumption of the ambient heater 311 in this embodiment. In the example of Figure 5, the power consumption of the ambient heater 311 is reduced compared to the conventional example shown in Figure 4. The power consumption of the ambient heater 311 during the WU period 441B and the image forming period 442B in Figure 5 is 40 [W], which is different from the WU period 441A and the image forming period 442A in Figure 4.

[0050] Figure 5, similar to Figure 4, shows the sequence of image formation transitions from standby mode 450B to wake-up mode 451B, then to image formation mode 452B, and finally back to standby mode 453B. Furthermore, Figure 5 shows the transition from standby mode 453B to sleep mode 454B after a predetermined time has elapsed, and then to plug-in mode 455B when the main switch 10 is turned off.

[0051] The ambient heater 311 has an upper limit temperature 401 of 44 degrees Celsius and a lower limit temperature 402 of 38 degrees Celsius set for the time progression 403A of the surface temperature of the photosensitive drum 31, similar to Figure 4. The change in the power consumption of the ambient heater 311 is shown in the time progression 412B. During the standby period 440B, 443B, sleep period 444B, and plug-in period 445B, the temperature of the ambient heater 311 is adjusted by the control unit 14, similar to Figure 4. During the standby period 440B, 443B, sleep period 444B, and plug-in period 445B, the ambient heater 311 is intermittently supplied with power of 0[W] and 80[W] at predetermined intervals. During the WU period 441B and image forming period 442B, the ambient heater 311 is intermittently supplied with power of 0[W] and 40[W] at predetermined intervals. During the WU period 441B and the image formation period 442B, the ratio of the period during which power is supplied to the environmental heater 311 (40[W]) to the period during which power supply is stopped (0[W]) is changed.

[0052] CPU 8 adjusts the lighting interval by thinning the lighting signal generated by comparator 319 via transistor 320 using PWM (PulseWidthModulation) control at WU (451B) and image formation (452B). This controls the power supply to the environmental heater 311. By controlling the power supply with PWM, the amount of power supplied to the environmental heater 311 is limited to 40[W] to prevent condensation during paper feeding.

[0053] Condensation during paper feeding, which occurs when a large amount of discharge products are generated at high ambient temperatures and humidity, can cause image blurring. An effective countermeasure against condensation during paper feeding is to raise the temperature and lower the relative humidity. Since the internal temperature of printer 1 becomes relatively high during paper feeding, even if the power supplied to the ambient heater 311 is 40[W], it is effective against condensation during paper feeding.

[0054] The CPU 8 switches the level of the signal input to the transistor 320 according to the amount of moisture, and also performs PWM control to switch the level of the signal at shorter intervals. As described above, this embodiment assumes that the amount of moisture is always higher than a predetermined value. During the standby period 440B, 443B, and sleep period 444B, when the CPU 8 does not control the power of the environmental heater 311, it inputs a low-level signal to the transistor 320. Also, during the plug-in period 445B, 445B, when no power is supplied to the CPU 8, the output of the CPU 8 becomes open, which is equivalent to when a low-level signal is input to the transistor 320. Because a low-level signal is input from the CPU 8 to the transistor 320, the temperature control of the environmental heater 311 is mainly performed by the control unit 14.

[0055] During the WU period 441B and the image formation period 442B, the rate of increase in the temperature over time 403B in this embodiment is gentler than that of the conventional temperature over time 403A, as the rate of increase in the power over time 412B decreases. The CPU 8 cuts off the power supply to the environmental heater 311 by inputting a high-level signal to the transistor 320. The CPU 8 performs PWM control of the lighting signal generated by the comparator 319 by controlling the ratio (duty cycle) of the high-level and low-level signals input to the transistor 320. When a high-level signal is input to the transistor 320, the lighting signal is forced to a low level, and the lighting interval is reduced. When a low-level signal is input to the transistor 320, the lighting signal is used directly to control the environmental heater 311.

[0056] The change in the current consumption value of printer 1 is shown in the time trend of the current consumption value 423B. The current value obtained by subtracting 40[W] of current from the outlet rating 421 becomes the upper limit of the total current value that can be used by printer 1 excluding the environmental heater 311 422B. Therefore, the power with 40[W] subtracted is distributed to the heater of the fuser 36. As shown in Figure 4, conventionally it was necessary to reserve 80[W] for the environmental heater 311, so in this embodiment, more power can be reserved for the heater of the fuser 36 than in the conventional case. As a result the WUT is reduced, and the WU period 441B in this embodiment is shorter than the conventional WU period 441A.

[0057] Furthermore, when implementing condensation prevention measures during standby periods 440B, 443B, sleep period 444B, and plug-in period 445B, the environmental heater 311 is lit at 80W because the internal temperature of printer 1 is relatively low. Condensation during shutdown occurs when the relative humidity increases as the temperature drops, making it more likely that moisture will adhere to the discharge products. 80W of power is required because the environmental heater 311 needs to be heated from a low temperature state.

[0058] This explanation uses an 80W environmental heater 311 for the EU (European Union) 230V as an example. Figure 6 is a table showing the commercial power supply voltage and the power consumption of the environmental heater 311 by country. This table shows the cases for Japan (JP), the United States (US), and the EU.

[0059] The power consumption during shutdown indicates the power consumption when the environmental heater 311 is lit without power control. The power consumption during shutdown is the power consumption during the standby period 440B, 443B, sleep period 444B, and plug-in period 445B. The power consumption during paper feeding indicates the power consumption when the environmental heater 311 is power controlled. The power consumption during paper feeding is the power consumption during the WU period 441B and image forming period 442B.

[0060] By setting the duty cycle of the PWM signal for the US and EU to 50% and the duty cycle of the PWM signal for Japan to 33%, the power supplied to the environmental heater 311 will be approximately 40W. The duty cycle of the PWM signal is such that when transistor 320 is conductive, the environmental heater 311 turns off, with off being 100% and on being 0%. The higher the value of the PWM signal duty cycle, the lower the power consumption of the environmental heater 311.

[0061] Figure 7 is a flowchart illustrating the process from acquiring a print job to ejecting the printed document. This process begins when the user inputs a print job to printer 1 from PC 9 or control unit 6.

[0062] When CPU8 acquires a print job, it starts power control of the environmental heater 311 just before transitioning to WU (S900). Power control of the environmental heater 311 will be described later. After controlling the power of the environmental heater 311, CPU8 performs WU until the fuser 36 reaches a temperature at which it can fix the toner image (S901). During WU, power is supplied to the fuser 36 to reach a fixing temperature. Since a rapid temperature rise is required to shorten FCOT, the fuser 36 is supplied with the maximum possible power. When WU is finished, CPU8 performs image formation operations based on the print job (S902). After the completion of the image formation operations, CPU8 transitions to sleep mode after a predetermined time has elapsed, or the print operation is terminated when the main switch 10 is turned off by the user.

[0063] Figure 8 is a flowchart showing the power control of the environmental heater 311 of the S900.

[0064] The CPU 8 sets the duty cycle of the PWM signal to 0% (S600). To achieve this, the environmental heater 311 is turned on by the control unit 14. The CPU 8 detects the AC voltage using the direction detection unit 501 and determines whether the detected AC voltage is 100[V] or not (S601). If it is 100[V] (S601:Y), the CPU 8 sets the DutyPerSet variable to 33% (S602). If it is not 100[V] (S601:N), the CPU 8 sets the DutyPerSet variable to 50% (S603). Here, the DutyPerSet variable is set based on the voltage of the commercial power supply in the country where the printer 1 is installed and the power consumption of the environmental heater 311. This indicates that if the printer 1 is installed in Japan, the AC voltage is 100[V] and the DutyPerSet variable is set to 33%. If printer 1 is installed in US or EP, the AC voltage is set to 50% instead of 100[V], and the DutyPerSet variable is set to 50%.

[0065] CPU8 determines whether printer 1 is operating at 451B during WU or 452B during image formation (S604). If it is 451B during WU or 452B during image formation (S604:Y), CPU8 sets the DutyPerSet variable to the duty cycle of the PWM signal (S605). If it is not 451B during WU or 452B during image formation (S604:N), CPU8 sets the duty cycle of the PWM signal to 0% (S607). After setting the duty cycle of the PWM signal to 0%, CPU8 returns to the process in S604.

[0066] CPU8, which has set the DutyPerSet variable to the duty cycle of the PWM signal, determines whether printer 1 is operating at 454B in sleep mode or 455B in plug-in mode (S606). If it is 454B in sleep mode or 455B in plug-in mode (S606:Y), CPU8 terminates power control of the environmental heater 311 because the power supply is cut off. If it is not 454B in sleep mode or 455B in plug-in mode (S606:N), CPU8 sets the duty cycle of the PWM signal to 0% (S607). After setting the duty cycle of the PWM signal to 0%, CPU8 returns to processing S604.

[0067] As described above, by prioritizing power supply to the fuser 36 and suppressing the power consumption of the environmental heater 311 through power control during WU 451B or image formation 452B, it is possible to shorten the WUT. In addition, by appropriately adjusting the surface temperature of the photosensitive drum 31 while appropriately supplying power to the environmental heater 311, it is possible to suppress the occurrence of condensation on the surface of the photosensitive drum 31.

[0068] (Second Embodiment) The configuration of the printer 1 in the second embodiment is the same as that of the first embodiment shown in Figures 1 and 2, so a description will be omitted. In the second embodiment, the power control of the environmental heater 311 differs from that of the first embodiment. The differences from the first embodiment will be explained. In the second embodiment, the environmental heater is divided into two. The two environmental heaters have the same power consumption and are built into the photosensitive drum 31.

[0069] Figure 9 is an explanatory diagram of the configuration of the control unit of the second embodiment, which corresponds to the control unit 14 in Figure 3. The environmental heater is divided into environmental heaters 311X and 311Y.

[0070] The control unit 340 includes a triac 314 that controls the supply of commercial power 13 to the environmental heaters 311X and 331Y, and a triac 331 that controls the supply of power to only the environmental heater 311Y. The triacs 314 and 331 can be any switches that can electrically switch between supplying and disconnecting power. The triacs 314 and 331 are connected to phototriac couplers 315 and 333. The collector terminals of transistors 334 and 335 are connected to the phototriac couplers 315 and 333. The base terminals of transistors 334 and 335 are connected to the output terminal of comparator 319 and are emitter-grounded.

[0071] In this configuration, triacs 314 and 331 are connected to the output terminals of comparator 319 via phototriac couplers 315 and 333 and transistors 334 and 335. Transistors 334 and 335 serve to electrically isolate the connection between the output terminals of comparator 319 and phototriac couplers 315 and 333. Furthermore, transistor 336 is connected to phototriac coupler 333. Transistor 336 has its collector connected to phototriac coupler 333, its base connected to CPU 8, and is common emitter. Phototriac coupler 333 is connected to CPU 8 via transistor 336.

[0072] If the output voltage of the temperature sensor 312 is lower than the output voltage output of the temperature setting unit 318, the output of the comparator 319 will be high level. Conversely, if it is lower, the output of the comparator 319 will be low level. When the output of the comparator 319 is high level, the outputs of transistors 334 and 335 will also be high level. Conversely, when the output of the comparator 319 is low level, the outputs of transistors 334 and 335 will also be low level.

[0073] When a high-level signal is input to phototriac couplers 315 and 333, triacs 314 and 331 are turned on, and power is supplied to the commercial power supply 13 and the environmental heaters 311X and 311Y. In this case, the environmental heaters 311X and 311Y generate heat. Conversely, when a low-level signal is input to phototriac couplers 315 and 333, triacs 314 and 331 are turned off, and power is cut off between the commercial power supply 13 and the environmental heaters 311X and 311Y. In this case, the environmental heaters 311X and 311Y do not generate heat.

[0074] When a high-level signal is input to the input transistor 336 of the phototriac coupler 333 from the CPU 8, a low-level signal is input even if the output of transistor 335 is high-level. Also, when a high-level signal is input to the input transistor 336 from the CPU 8, if the output of transistor 335 is low-level, the signal input to the phototriac coupler 333 remains low-level.

[0075] The output of transistor 335 remains high if a low-level signal is input to transistor 336 from CPU 8. The output of transistor 335 remains low if a low-level signal is input to transistor 336 from CPU 8.

[0076] The CPU 8 can select between lighting only the environmental heater 311Y or lighting both the environmental heaters 311X and 311Y by switching the triac 331 on and off via the transistor 336. When only the environmental heater 311Y is lit, the total power consumption of the environmental heaters is 40[W], and when both the environmental heaters 311X and 311Y are lit, the total power consumption of the environmental heaters is 80[W].

[0077] The time course of the surface temperature of the photosensitive drum 31 and the time course of the power consumption of the printer 1 in the second embodiment are the same as in the example of the first embodiment shown in Figure 5, so their explanation is omitted. Figure 10 is a flowchart showing the power control of the environmental heaters 311X and 311Y of S900 in Figure 7.

[0078] The CPU 8 turns on the triac 331 via the transistor 336, thereby lighting both the environmental heater 311X and the environmental heater 311Y (S700). The triac 314 is controlled to be turned on by the control unit 340. The CPU 8 determines whether the printer 1 is operating in WU mode 451B or image formation mode 452B (S701). If it is WU mode 451B or image formation mode 452B (S701:Y), the CPU 8 turns off the triac 331 via the phototriac coupler 333, lighting only the environmental heater 311X (S702). If it is not WU mode 451B or image formation mode 452B (S701:N), the CPU 8 turns on the triac 331 via the phototriac coupler 333, lighting both the environmental heater 311X and the environmental heater 311Y (S704).

[0079] With only the ambient heater 311X lit, CPU8 determines whether printer 1 is operating in sleep mode 454B or plug-in mode 455B (S703). If it is in sleep mode 454B or plug-in mode 455B (S703:Y), CPU8 terminates power control of the ambient heater. If it is not in sleep mode 454B or plug-in mode 455B (S703:N), CPU8 turns on the triac 331 via the phototriac coupler 333, lighting both ambient heaters 311X and 311Y (S704). After that, CPU8 proceeds to S701.

[0080] As described above, by prioritizing power supply to the fuser 36 and reducing the power consumption of the environmental heaters 311X and 311Y through power control during WU (Wake-Up Time) 451B or image formation 452B, the WUT (Wake-Up Time) can be shortened. Power consumption can be reduced by lighting only one of the environmental heaters 311X and 311Y as needed. In addition, by appropriately adjusting the surface temperature of the photosensitive drum 31 while appropriately supplying power to the environmental heater 311, the occurrence of condensation on the surface of the photosensitive drum 31 can be suppressed.

[0081] (Third embodiment) In the first embodiment, the case where priority is given to supplying power to the fuser 36 was described. In the third embodiment, the case where priority is given to supplying power to the cassette heater that dehumidifies moisture adhering to the recording material will be described. When the recording material absorbs moisture, it can cause curling and lead to jams. Furthermore, when the recording material absorbs moisture, it can also lead to transfer defects due to moisture. For this reason, the cassette heater is placed on the bottom surface of the paper feed cassette 2 to dehumidify the recording material.

[0082] Figure 11 is an internal configuration diagram of the printer according to the third embodiment. Printer 1a is configured by adding a cassette heater 16 and a cassette heater switch 15 to the printer 1 of the first embodiment. The other configurations are the same and will not be described. The cassette heater switch 15 is a manual switch located near the base of the power cord of printer 1a and is operated by the user according to the installation environment of printer 1a. When the cassette heater switch 15 is turned on, the cassette heater 16 is constantly energized and generates heat without the intervention of the CPU 8.

[0083] In humid environments, the recording material curls due to moisture absorption. This makes it more likely for the recording material to get caught on the transport path when the paper transport mechanism 5 transports it, increasing the rate of jams. In addition, the moisture absorbed by the recording material causes the potential during toner image transfer to become unstable, reducing transferability. Therefore, depending on the installation environment of the printer 1a, the cassette heater switch 15 is turned on, and the cassette heater 16 is kept lit at all times. This raises the ambient temperature and lowers the relative humidity, suppressing moisture absorption by the recording material.

[0084] Thus, the cassette heater 16 has limited operating environments and usage cases. However, considering the cases in which it may be used, when the cassette heater switch 15 is turned on, power supply to the cassette heater 16 is prioritized. The power consumption of the cassette heater 16 is, for example, approximately 20 [W]. Similar to the first embodiment, the power consumption of the ambient heater 311 is reduced from 80 [W] to 40 [W] during WU 451C and during image formation 452C. The reduced power supplied to the ambient heater 311 is supplied to the cassette heater 16. This ensures that the amount of power supplied to the cassette heater 16 is secured.

[0085] Figure 12 is an explanatory diagram of the configuration of the temperature control controller of the third embodiment. The temperature control controller of the third embodiment has the same configuration as the temperature control controller of the first embodiment shown in Figure 3, with the addition of a cassette heater 16, a cassette heater switch 15, and a zero-cross detection unit 507. The other components are the same and are therefore omitted from the explanation.

[0086] The cassette heater 16, the cassette heater switch 15, and the zero-cross detection unit 507 are connected in series. The cassette heater 16 is connected to the commercial power supply 13 via the power connection terminal 11, and the zero-cross detection unit 507 is connected to the commercial power supply 13 via the power connection terminal 12.

[0087] When the user operates the cassette heater switch 15 to the ON position, the zero-cross detection unit 507 and the commercial power supply 13 become conductive. The CPU 8 can detect the zero-cross of the AC voltage supplied from the commercial power supply 13 using the zero-cross detection unit 507. Also, when the cassette heater switch 15 is turned ON, the cassette heater 16 becomes conductive with the commercial power supply 13, lights up, and generates heat.

[0088] The AC voltage supplied from the commercial power supply 13 is a sine wave whose voltage value periodically changes across 0[V]. A zero crossing is the timing when the voltage value becomes 0[V]. When the zero crossing detection unit 507 and the commercial power supply 13 are energized, the zero crossing detection timing occurs with the same period as the AC voltage supplied from the commercial power supply 13. The zero crossing detection unit 507 detects a zero crossing when the cassette heater switch 15 is turned on and notifies the CPU 8 that a zero crossing has been detected. The CPU 8 can detect that the cassette heater switch 15 has been turned on by receiving the notification of zero crossing detection from the zero crossing detection unit 507.

[0089] Figure 13 is an explanatory diagram illustrating the time evolution of the current consumption of the printer 1a, the surface temperature of the photosensitive drum 31, and the power consumption of the ambient heater 311 in the third embodiment. In Figure 13, priority is given to the power supply to the cassette heater 16. As a comparative example, Figure 4, which was described in the first embodiment, is used.

[0090] The power consumption of the environmental heater 311 during the WU period 441C and the image formation period 442C differs from that of the WU period 441A and the image formation period 442A in Figure 4. The power consumption of the environmental heater 311 during the WU period 441C and the image formation period 442C is 80[W] in Figure 4 and 40[W] in Figure 13.

[0091] Figure 13, like Figure 4, shows a series of image formation transitions from standby mode (450C) to wake-up mode (451C), then to image formation mode (452C), and finally back to standby mode (453C). Furthermore, Figure 13 shows the transition from standby mode (453C) to sleep mode (454C) after a predetermined time has elapsed, and then to plug-in mode (455C) when the main switch 10 is turned off.

[0092] The environmental heater 311 has an upper limit temperature 401 of 44 degrees Celsius and a lower limit temperature 402 of 38 degrees Celsius set for the temperature change over time 403C, similar to Figure 4. The change in power consumption of the environmental heater 311 is shown in the time change 412C. During the standby period 440C, 443C, sleep period 444C, and plug-in period 445C, the temperature of the environmental heater 311 is adjusted by the control unit 14, similar to Figure 4. During the standby period 440C, 443C, sleep period 444C, and plug-in period 445C, the environmental heater 311 is intermittently supplied with power of 0[W] and 80[W] at predetermined intervals. During the WU period 441C and image forming period 442C, the environmental heater 311 is intermittently supplied with power of 0[W] and 40[W] at predetermined intervals. During the WU period 441C and the image formation period 442BC, the ratio of the period during which power is supplied to the environmental heater 311 (40[W]) to the period during which power supply is stopped (0[W]) is changed.

[0093] The CPU 8 adjusts the lighting interval by selectively filtering the lighting signals generated by the comparator 319 via PWM control through the transistor 320 at WU (451C) and image formation (452C), similar to the first embodiment. This controls the power supply to the environmental heater 311. With this power supply control, the amount of power supplied to the environmental heater 311 is set to 40 [W] to prevent condensation during paper feeding.

[0094] The CPU 8 switches the level of the signal input to the transistor 320 according to the amount of moisture, and also controls the signal level to switch at shorter intervals. During standby periods 440C, 443C, and sleep period 444C, when the power control of the environmental heater 311 is not performed, the CPU 8 inputs a low-level signal to the transistor 320.

[0095] Furthermore, during the plug-in period 445C when no power is supplied to the CPU 8, the output of the CPU 8 becomes open, which is equivalent to when a low-level signal is input to the transistor 320. During the WU period 441C and the image formation period 442C, the time evolution of the power amount 412C decreases, resulting in a gentler rise in the temperature time evolution 403C of this embodiment compared to the conventional temperature time evolution 403A.

[0096] In the third embodiment, when the zero-crossing detection unit 507 detects a zero-crossing, the CPU 8 controls the environmental heater 311 via the transistor 320 using PWM control to suppress power consumption. The change in the current consumption value of the printer 1a is shown in the time change of the current consumption value 423C.

[0097] The current value obtained by subtracting 40[W] of current from the outlet rating 421 becomes the upper limit of the current value that can be used by the printer 1a, excluding the environmental heater 311, 422C. The time progression of the current consumption value 423C always includes a current value equivalent to the power consumption of the cassette heater 16, which is 20[W]. The time progression of the current consumption value 424C, after subtracting the current consumption value by the cassette heater 16, is shown by a dotted line. The upper limit of the time progression of the current consumption value 424C, which is the upper limit of the printer 1a's usage limit 422C, is the current value obtained by subtracting 20[W] of current from the outlet rating.

[0098] During the WU period 441C and the image forming period 442C, the temperature control of the fuser 36 is performed, causing the current consumption of the printer 1a to approach the outlet rating. At this time, the 40[W] reduction from the environmental heater 311 due to the paper feeding condensation countermeasure is distributed to the cassette heater 16, which is 20[W], thereby suppressing moisture absorption by the recording material.

[0099] Figure 13 shows that by controlling the illumination of the environmental heater 311 and prioritizing the power supply to the cassette heater 16, the printer 1a's usage limit 422C can be made higher than the usage limit 422B of the first embodiment. Furthermore, the surplus 20[W] of power distributed to the cassette heater 16 can be used to supply power to the fuser 36, thus shortening the WU period 441C.

[0100] Figure 13 shows the transition from standby mode (450C) to wake-up mode (451C), then to image formation mode (452C), back to standby mode (453C), and finally to sleep mode (454C) after a predetermined time has elapsed. Furthermore, Figure 13 shows the transition to plug-in mode (455C) when the main switch 10 is turned off.

[0101] The power consumption of the environmental heater 311 is 40[W] during the WU period 441C and the image formation period 442C, and 80[W] during the standby period 440C, 443C, sleep period 444C, and plug-in period 445C. In addition, the power consumption of the cassette heater 16, 20[W], is always added.

[0102] During the WU period 441C and the image forming period 442C, the power consumption is reduced by controlling the operation of the ambient heater 311 in order to ensure sufficient power for the cassette heater 16. Since the power consumption of the cassette heater 16 is 20W compared to the 40W reduction achieved by controlling the power supply to the ambient heater 311, the surplus 20W becomes available for supply to the fuser unit 36.

[0103] Figure 14 is a flowchart showing the power control of the environmental heater 311 in S900 of Figure 7. The processes S650 to S653 in Figure 14 are the same as the processes S600 to S603 in Figure 8, so their explanation is omitted.

[0104] The CPU 8, which has set the DutyPerSet variable, determines whether or not the cassette heater switch 15 has been turned on by checking whether or not a zero crossing has been detected by the zero crossing detection unit 507 (S654).

[0105] If the cassette heater switch 15 is ON (S654:Y), the CPU 8 determines that the cassette heater 16 is lit and secures power to supply to the cassette heater 16. The CPU 8 determines whether the printer 1 is operating during WU (Wake-Up) (451C) or during image formation (452C) (S655). Subsequently, the CPU 8 performs the same processing as in S604 to S607 in Figure 8 (S655 to S658) and terminates power control of the ambient heater 311.

[0106] If the cassette heater switch 15 is off (S654:N), the CPU 8 determines that the cassette heater 16 is off and does not reserve power to supply to the cassette heater 16. In this case, the CPU 8 sets the duty cycle of the PWM signal to 0% (S658). After setting the duty cycle of the PWM signal to 0%, the CPU 8 returns to processing S654.

[0107] As a result, by prioritizing power supply to the cassette heater 16 and suppressing the power consumption of the environmental heater 311 through power control during WU (451C) or image formation (452C), the WUT (Wake-to-Utr) time can be shortened. Furthermore, stable paper transport and image quality can be maintained even in humid environments. In addition, by appropriately adjusting the surface temperature of the photosensitive drum 31 while appropriately supplying power to the environmental heater 311, the occurrence of condensation on the surface of the photosensitive drum 31 can be suppressed.

Claims

1. Image forming means for forming an image on a recording material, A heat source for adjusting the temperature of the image forming means, The system includes a control means that supplies a first amount of power to the heat source in a first state, supplies a second amount of power smaller than the first amount to the heat source in a second state, and stops supplying power to the heat source in a third state. Image forming apparatus.

2. The control means, in the second state, supplies the second amount of power to the heat source by intermittently supplying power to the heat source. The image forming apparatus according to claim 1.

3. The control means is configured to change the ratio between the period during which power is supplied and the period during which power is not supplied, with respect to the intermittent supply of power to the heat source in the second state. The image forming apparatus according to claim 2.

4. The control means is In the first state, if the image forming means exceeds the upper limit temperature, the power supply to the heat source is stopped, and if the image forming means falls below the lower limit temperature, a first amount of power is supplied to the heat source. In the second state, if the image forming means exceeds the upper limit temperature, the power supply to the heat source is stopped, and if the image forming means falls below the lower limit temperature, a second amount of power is supplied to the heat source. The image forming apparatus according to claim 1.

5. The control means is A setting temperature means that outputs a reference voltage corresponding to the set temperature of the image forming means, A temperature sensor for detecting the temperature of the image forming means, A comparison means for comparing a voltage corresponding to the temperature detected by the temperature sensor with the reference voltage, The device is characterized by having a switch that controls the power supply to the heat source in accordance with a lighting signal representing the comparison result by the comparison means. The image forming apparatus according to claim 4.

6. The system is characterized by comprising a main control means that controls the ratio of the high level to the low level of the lighting signal in the second state, thereby supplying a second amount of power from the control means to the heat source. The image forming apparatus according to claim 5.

7. The main control means is characterized in that, in the first state, it does not control the ratio of the high level to the low level of the lighting signal. The image forming apparatus according to claim 6.

8. The heat source includes a first heater and a second heater. The control means is characterized in that, in the first state, it supplies power to both the first heater and the second heater, and in the second state, it supplies power only to the first heater. The image forming apparatus according to claim 1.

9. The system is characterized by comprising a main control means for interrupting the power supply to the second heater by the control means in the second state, The image forming apparatus according to claim 8.

10. The image forming means comprises an image carrier on which the image is formed, a transfer means for transferring the image from the image carrier to the recording material, and a fixing means for fixing the image to the recording material by heating the recording material on which the image has been transferred. In the second state, the power obtained by reducing the second power amount from the first power amount is supplied to the fixing means, The image forming apparatus according to claim 1.

11. A paper feed cassette in which the aforementioned recording material is stored, The paper feed cassette includes a cassette heater for dehumidifying the recording material stored in the paper feed cassette, In the second state, the amount of power obtained by reducing the second energy amount from the first energy amount is supplied to the cassette heater instead of the fixing means, The image forming apparatus according to claim 10.

12. The heat source is characterized by heating the image carrier. The image forming apparatus according to claim 10.

13. The heat source is characterized by being built into the image carrier. The image forming apparatus according to claim 10.

14. In the second state, the power obtained by reducing the second power amount from the first power amount is supplied to the image forming means, The image forming apparatus according to claim 1.

15. The second state is characterized by being the warm-up and image formation phases of the image forming apparatus. An image forming apparatus according to any one of claims 1 to 14.

Images