Device

Abstract

To reduce noise and current consumption of a cooling fan by controlling drive start time of the cooling fan.SOLUTION: An image formation device 1 comprises: a fixation heater 25a; a temperature control part 51a controlling power supplied from an AC power supply 12 to the fixation heater 25a by an AC output control element 26a to control heater temperature; a cooling fan 37a suppressing increase in temperature of the AC output control element 26a; a drive part 36a driving the cooling fan 37a. The image formation device 1 further comprises: an AC voltage detection part 28a detecting input voltage Vac of the AC power supply 12; and a cooling control part 50a on-off controlling the drive part 36a according to level fluctuation of the input voltage Vac in order to maintain temperature Ts of the AC output control element 26a within an allowable temperature range. The cooling control part 50a determines drive start time t1fs of the cooling fan 37a on the basis of the input voltage Vac of the AC power supply 12.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an apparatus. [Background technology]

[0002] In electrophotographic image forming apparatuses, power is supplied to the heater in the fixing unit through an AC output control element (e.g., a triac) for controlling power. To prevent damage to the element (triac) due to heat generation, a cooling fan is provided and the fan's rotation speed is known to be variably controlled, and there is technology to control the rotation speed by fluctuations in the input voltage.

[0003] Patent Document 1 discloses a configuration in which the airflow rate of a fan is increased when the input voltage falls below a lower limit, in order to prevent a shortened life span or breakdown of an AC output control element for heater control due to thermal stress. In more detail, when the input voltage level (detection voltage) drops, the output from the second voltage comparator is corrected to increase the switching frequency of the switching semiconductor Q1 above normal. This discloses a configuration in which the voltage applied to the fan 17 is increased, and the airflow rate of the fan 17 is instantly increased by the ratio of the drop in the input voltage.

[0004] However, in conventional image forming apparatuses, when the voltage drops, the fan flow rate is increased to protect the AC output control element from being cooled, but this causes problems such as fan noise and increased current consumption.

[0005] Patent Document 1 discloses controlling the operation of a fan using an input voltage. However, Patent Document 1 does not solve the problems of fan noise and increased current consumption. Summary of the Invention [Problem to be solved by the invention]

[0006] An embodiment of the present invention has been made in consideration of the above, and has an object to reduce the noise of the cooling fan and reduce current consumption by controlling the time when the cooling fan starts to be driven. [Means for solving the problem]

[0007] In order to solve the above problem, the invention described in claim 1 is an apparatus comprising: a heater; a temperature control unit that controls the power supplied from an AC power supply to the heater using an AC output control element to control the heater temperature; a cooling fan that suppresses an increase in temperature of the AC output control element; and a drive unit that drives the cooling fan, wherein the apparatus further comprises an AC voltage detection unit that detects an input voltage of the AC power supply; and a cooling control unit that controls on / off of the drive unit in response to fluctuations in the level of the input voltage in order to maintain the temperature of the AC output control element within an allowable temperature range, and the cooling control unit determines a drive start time of the cooling fan based on the input voltage of the AC power supply. Effect of the Invention

[0008] According to the present invention, by controlling the time when the cooling fan starts to be driven, it is possible to reduce the noise of the cooling fan and reduce current consumption. [Brief description of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view showing a schematic mechanical configuration of an image forming apparatus according to a first embodiment of the present invention. [Diagram 2] 1 is a circuit diagram for explaining a configuration of a power supply device mounted on an image forming apparatus according to a first embodiment of the present invention. [Diagram 3] 1 is a functional block diagram showing functions of an image forming apparatus according to a first embodiment of the present invention. [Figure 4] 5 is a timing chart showing an overview of fan drive time control by AC power supply voltage in the image forming apparatus according to the first embodiment of the present invention. [Diagram 5]1(a) is a graph (part 1) showing an example of the temperature of the AC output control element and the elapsed time when the input voltage of the AC power supply is different in the image forming apparatus according to the first embodiment of the present invention, and FIG. 1(b) is a diagram (part 1) showing a control table storing an example of the relationship between the input voltage, the temperature of the AC output control element, and time in the image forming apparatus according to the first embodiment of the present invention. [Figure 6] 4 is a flowchart (part 1) for explaining the operation of the image forming apparatus according to the first embodiment of the present invention. [Figure 7] 10 is a timing chart showing an overview of fan drive time control based on a print-OFF time in an image forming apparatus according to a second embodiment of the present invention. [Figure 8] 1A is a graph (part 2) showing an example of the temperature of the AC output control element when the print OFF time is different in an image forming apparatus according to a second embodiment of the present invention, (b) is a diagram (part 2) showing a control table storing an example of the relationship between the temperature of the AC output control element and time in an image forming apparatus according to a second embodiment of the present invention, and (c) is a diagram (part 3) showing a control table storing an example of the relationship between the print OFF time and the temperature of the AC output control element in an image forming apparatus according to a second embodiment of the present invention. [Figure 9] 10 is a second flowchart illustrating the operation of the image forming apparatus according to the second embodiment of the present invention. [Figure 10] 1A is a graph (part 3) showing an example of the temperature of the output control element when the environmental temperature is different in an image forming apparatus according to a third embodiment of the present invention, and FIG. 1B is a diagram (part 4) showing a control table storing an example of the time t for the temperature to rise from the environmental temperature Tk to the upper limit temperature Ttop in an image forming apparatus according to a third embodiment of the present invention. [Figure 11] 13 is a flowchart (part 3) for explaining the operation of the image forming apparatus according to the third embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, the present invention will be described in detail with reference to the embodiments shown in the drawings. The present invention has the following configuration in order to reduce the noise of the cooling fan and reduce current consumption by controlling the drive start time of the cooling fan. That is, the device of the present invention is a device comprising a heater, a temperature control unit that controls the power supplied from the AC power supply to the heater using an AC output control element to control the heater temperature, a cooling fan that suppresses an increase in temperature of the AC output control element, and a drive unit that drives the cooling fan, and is characterized in that it comprises an AC voltage detection unit that detects the input voltage of the AC power supply, and a cooling control unit that controls the on / off of the drive unit in response to fluctuations in the level of the input voltage in order to maintain the temperature of the AC output control element within an allowable temperature range, and the cooling control unit determines the time when the cooling fan will start to be driven based on the input voltage of the AC power supply. With the above configuration, the cooling fan drive start time can be controlled to reduce the noise of the cooling fan and reduce current consumption. The features of the present invention described above will be described in detail with reference to the following drawings. However, unless otherwise specified, the components, types, combinations, shapes, relative arrangements, etc. described in the embodiments are merely illustrative examples and do not intend to limit the scope of the present invention. The above-mentioned features of the present invention will be described in detail below with reference to the drawings.

[0011] First Embodiment <Image forming device> FIG. 1 is a cross-sectional view showing a schematic mechanical configuration of an image forming apparatus according to a first embodiment of the present invention. 1 is a digital multifunction machine having a copy function, a printer function, a facsimile function, etc. The application switching key of the operation unit 2a allows the user to select the copy function, the printer function, and the facsimile function by switching between them in sequence. When the copy function is selected, the mode becomes copy mode, when the printer function is selected, the mode becomes printer mode, and when the facsimile mode is selected, the mode becomes facsimile mode. Here, when the user performs a selection operation on a key for selecting a copy function displayed on the operation unit 2a, the image forming apparatus 1 performs the following operation.

[0012] <Copy mode> Referring to FIG. 1, a copy mode will be briefly described as an example of the flow of image formation in image forming apparatus 1. In the copy mode, documents are fed one by one from a stack of documents set in an automatic document feeder (ADF) 2 to an image reading section 3, and image information is read by the image reading section 3. The read image information is then converted into optical information by a writing unit 4 via an image processing means, and a photoconductor drum 6 is uniformly charged by a charger and then exposed to the optical information from the writing unit 4, forming an electrostatic latent image. The image forming unit 5 is a print engine that forms an image on a print sheet. In the image forming unit 5, the electrostatic latent image on the photoconductor drum 6 is developed by the developing unit 7 into a toner image. This toner image is transferred to the transfer paper by the conveyor belt 8. The toner image is fixed on the transfer paper by the fixing unit 9, and the transfer paper is discharged.

[0013] The image forming apparatus 1 is provided with a power supply device 10, which converts power supplied from an AC power supply 12, which is an external power supply, into DC power and supplies the DC power to the loads of the above-mentioned components. The device according to the present invention can be applied to appliances other than the image forming device 1, such as microwave ovens, electric water heaters, rice cookers, cooking appliances, washer-dryers, dryers, and electric stoves.

[0014] <Power supply> FIG. 2 is a circuit diagram for explaining the configuration of a power supply device mounted on the image forming apparatus according to the first embodiment of the present invention. The image forming apparatus 1 includes a power supply device 10, a control board 14, and a halogen heater 25 as its main components. The power supply device 10 includes a DC voltage generating unit 35, which will be described later, a triac 26 that controls the flow of AC power supplied to the fixing unit, and an AC voltage detection circuit 28. The power supply device 10 generates a DC voltage (24 V, 5 V) from an AC power supply 12, which is a commercial AC power supply, and supplies the generated DC voltage to a control board 14. The power supply device 10 also supplies the AC voltage of the AC power supply 12 to a halogen heater 25 via a triac 26 provided in the power supply device 10. The control board 14 includes a CPU 15a, a ROM 15b, a RAM 15c, and a timer 15d. The CPU 15a includes A / D1 and A / D2, which convert input analog voltages into digital data.

[0015] The DC voltage generating unit 35 provided in the power supply device 10 is composed of a noise filter 16 that removes noise components from the AC supplied from the AC power supply 12, a diode bridge 17 that full-wave rectifies the AC, an aluminum electrolytic capacitor 18 that smoothes the pulsating component during full-wave rectification, a transformer 19 having primary to tertiary windings, an FET 20 used for switching, an IC 21 that controls the switching timing of the FET 20 based on a signal from the tertiary winding, a diode 22 that rectifies the low-voltage AC induced in the secondary winding of the transformer 19, an aluminum electrolytic capacitor 23 that smoothes the pulsating component, and a switching regulator 24 consisting of a DC / DC converter that generates 5 V from 24 V, and generates DC voltages of 24 V and 5 V from the AC voltage. The CPU 15a controls the supply / cut-off of AC voltage to the halogen heater 25 by providing a TRIAC control signal 27, which is an ON / OFF signal, to the triac . The CPU 15a controls the operations of the various components constituting the image forming apparatus 1 (FIG. 3).

[0016] The AC voltage detection circuit 28 includes a transformer 29 having a primary winding and a secondary winding, a diode bridge 30 that rectifies the low voltage AC induced in the secondary winding of the transformer 29, and a capacitor 31 that smoothes the pulsating component. The transformer 29 reduces the AC voltage supplied to the primary winding from the AC power source 12 to an AC voltage of about 5 V when it is induced in the secondary winding. The AC voltage of 5 V induced in the secondary winding of the transformer 29 is rectified and smoothed in the diode bridge 30 and the capacitor 31 to be converted into a DC voltage and output to the A / D1 port provided in the CPU 15 a. By employing the AC voltage detection circuit 28, the input voltage to the A / D1 port fluctuates depending on the magnitude of the AC voltage supplied to the primary winding of the transformer 29, and therefore the CPU 15a can detect fluctuations in the AC voltage of the AC power supply 12.

[0017] When the AC voltage detection circuit 28 shown in FIG. 2 is adopted, it is necessary to convert an AC voltage with a frequency of several tens of Hz into a low voltage that can be detected by the A / D1 port using a transformer 29, a diode bridge 30, and a capacitor 31, so that the transformer becomes large in size in terms of the component configuration. A temperature sensor 38 is disposed near the triac 26, and a voltage signal proportional to the heat generation temperature of the triac 26 detected by the temperature sensor 38 is input to the A / D2 port. A cooling fan 37 for cooling the triac 26 is disposed near the triac 26, and a power supply terminal of the cooling fan 37 is connected to a 24 V power supply, and one GND terminal is connected to the collector terminal of the transistor 36. The emitter terminal of the transistor 36 is connected to GND, and the base terminal of the transistor 36 is connected to the output port of the CPU 15a.

[0018] <Function block diagram> FIG. 3 is a functional block diagram showing functions of the image forming apparatus according to the first embodiment of the present invention. The image forming apparatus 1 includes a fixing heater 25a, an AC output control element 26a, a temperature control unit 31a, an AC voltage detection unit 28a, a cooling fan 37a, a drive unit 36a, a DC power supply 35a, a cooling control unit 50a, and a temperature sensor 38a. The fixing heater 25a is, for example, a halogen heater that can be supplied with AC power from an external power source. A halogen heater has a resistance characteristic in which the lower the temperature, the lower the resistance. Due to this resistance characteristic, an inrush current occurs when the current starts to flow, causing a voltage drop in the external power source. The AC output control element 26a is constituted by a triac 26, and is a switching element for controlling the on / off of the power supplied from the AC power source 12 to the fixing heater 25a. The temperature control unit 31a controls the power supplied from the AC power source 12 to the fixing heater 25a by the AC output control element 26a, thereby controlling the heater temperature. The AC voltage detector 28 a detects the input voltage Vac of the AC power supply 12 . The cooling fan 37a suppresses an increase in the temperature Ts of the AC output control element 26a. The driving unit 36a is configured by a transistor 36, and drives the cooling fan 37a by supplying power from a DC power supply 35a to the cooling fan 37a.

[0019] The DC power supply 35a is constituted by a DC voltage generating unit 35, and converts the power of the AC power supply 12 into DC power to supply voltages of 24V and 5V. The cooling control unit 50a controls the on / off of the drive unit 36a in response to fluctuations in the level of the input voltage Vac in order to maintain the temperature Ts of the AC output control element 26a within an allowable temperature range. The cooling control unit 50a is configured to off Based on this, the time to start driving the cooling fan 37a is determined. The cooling control unit 50a is configured to off Based on this, the time to start driving the cooling fan 37a is determined. The temperature sensor 38a is constituted by the temperature sensor 38, and measures the temperature Ts of the AC output control element 26a. The temperature sensor 39a is provided on the side of the image forming apparatus 1 and measures the environmental temperature Tk. The print-off time measurement unit 50b measures the print-off time t off Time the following.

[0020] <Fan operation time control> FIG. 4 is a timing chart showing an overview of fan drive time control by AC power supply voltage in the image forming apparatus according to the first embodiment of the present invention. In FIG. 4, the printing time is t 11 ~t 1fe The fan operation time is set to time t 1fs ~t 1fe Let us assume that. When the voltage of the AC power supply 12 is low, the current is increased in order to secure the power for the fixing heater 25a. Since the current flowing through the AC output control element 26a that controls the power supply to the fixing heater 25a increases, the temperature Ts of the AC output control element 26a increases. Conversely, when the voltage of the AC power supply 12 is high, the current flowing through the AC output control element 26a is small, and therefore the temperature Ts of the AC output control element 26a is lower than when the voltage is low. When the voltage of the AC power supply 12 is low, the temperature Ts of the AC output control element 26a becomes high, so the driving start time (t 1fs ) is advanced to prevent a temperature rise, and when the voltage of the AC power supply 12 is high, the temperature rise of the AC output control element 26a is small, so the drive start time (t 1fs ) to delay.

[0021] <Graph (part 1)> FIG. 5(a) is a graph (part 1) showing an example of the temperature of the AC output control element and the elapsed time when the input voltage of the AC power supply in the image forming apparatus according to the first embodiment of the present invention is different. That is, Fig. 5(a) shows the input voltage V ac 4 shows an example of the temperature Ts of the AC output control element and the elapsed time t when The cooling control unit 50a controls the input voltage V ac When the temperature Ts of the AC output control element 26a is changed, the upper limit temperature is set to, for example, 150° C. (T top) and the time t until the AC output control element 26a reaches a temperature at which it is not affected by heat is obtained and recorded as a control table 55 in the RAM 15c.

[0022] <Control table> FIG. 5(b) is a diagram (part 1) showing a control table storing an example of the relationship between the input voltage, the temperature of the AC output control element, and time in the image forming apparatus according to the first embodiment of the present invention. The control table 55 shown in FIG. ac , temperature Ts, and time t are stored in association with each other. Here, the input voltage V ac is the upper limit temperature 150℃ (T top ) is the input voltage of the AC power source 12 during printing, temperature Ts is the temperature of the AC output control element 26a, and time t is the time it takes for the AC output control element 26a to reach a temperature at which it is not affected by heat.

[0023] <Operation of the cooling control unit> (1) The cooling control unit 50a detects the input voltage V of the AC power source 12 detected by the AC voltage detection unit 28a. ac Get the. (2) The cooling control unit 50a controls the input voltage V ac The time t corresponding to is obtained from the control table 55. (3) The cooling control unit 50a sets the acquired time t as a start time in the timer 15d, and operates the cooling fan 37a when the time set in the timer 15d arrives. AC power supply 12 input voltage V ac Even if the temperature of the AC output control element 26a is low and the temperature rises quickly, the driving start time (t 12 ) to delay. On the other hand, the input voltage V ac When the temperature rise of the AC output control element 26a is slow, the fan start time (t 13 ) can be further delayed. This shortens the time during which noise is generated by the rotation of the cooling fan 37a, and also reduces the power consumption of the cooling fan 37a because the fan operation time is shortened.

[0024] <Flowchart (part 1)> FIG. 6 is a flowchart (part 1) for explaining the operation of the image forming apparatus according to the first embodiment of the present invention. When a print start signal is received from the print engine, the cooling control unit 50a starts operation. In step S10, the cooling control unit 50a 11 ), the AC voltage (AC voltage) V ac Detect. In step S20, the cooling control unit 50a determines whether the input voltage Vac is in a steady state (100 V±α (eg, α=5 V)). If the input voltage Vac is in a steady state (100 V±α (eg, α=5 V)), the process proceeds to step S30, where the cooling control unit 50a determines the fan start time to be time A, sets the timer 15d to time A, and starts the timer 15d. Here, when the timer 15d has timed the time t=A, it generates an interrupt signal INT and outputs it to the CPU 15a.

[0025] In step S70, when the cooling control unit 50a receives the interrupt signal INT from the timer 15d, it outputs a drive signal (1) to the drive unit 36a. When the drive signal (1) is input, the drive unit 36a applies a high-level signal to the base terminal of the transistor 36 to turn on the collector-emitter, and applies DC 24V to the cooling fan 37a. This operation starts the printing start (t 11 ) the cooling fan 37a is driven with a delay of time A from the start of the cooling process. In step S80, the cooling control unit 50a determines whether or not a print end signal has been received from the print engine, and repeats the process in step S80 until the print end signal is received. When a print end signal is received from the print engine, in step S90, the cooling control unit 50a outputs a stop signal (0) to the drive unit 36a. When the stop signal (0) is input, the drive unit 36a applies a low level signal to the base terminal of the transistor 36 to turn off the collector-emitter, and stops the rotation of the cooling fan 37a. This operation stops the cooling fan 37a.

[0026] If the input voltage Vac is not in a steady state (100V±α (for example, α=5V)), the process proceeds to step S40, where the cooling control unit 50a determines whether the input voltage Vac is lower than the steady state (Vac<100V-α). When the input voltage Vac is lower than the steady state (Vac<100V-α), in step S50, the cooling control unit 50a advances the fan start time (t=AB) from the steady state because the temperature rise of the AC output control element 26a is fast. That is, the cooling control unit 50a determines the fan start time to be time (t=AB), sets the time AB in the timer 15d, starts the timer 15d, and proceeds to step S70. Thereafter, the operation proceeds according to steps S70 to S90. Note that A and B are positive values. When the input voltage Vac is lower than that in the steady state, the temperature rise of the AC output control element becomes faster, so that the fan start time can be advanced by (t=AB) to operate the cooling fan 37a.

[0027] If the input voltage Vac is not lower than the steady state (Vac<100V-α), that is, if the input voltage Vac is higher than the steady state, in step S60, the cooling control unit 50a delays the fan start time (t=A+C) from the steady state because the temperature rise of the element 26a becomes gentler. That is, the cooling control unit 50a determines the fan start time to be time (t=A+C), sets the time t=A+C in the timer 15d, starts the timer 15d, and proceeds to step S70. Thereafter, the operation proceeds according to steps S70 to S90. Note that A and C are positive values. In this way, when the input voltage Vac is higher than the steady state, the temperature rise of the AC output control element becomes gradual, so that the fan start time can be delayed by (t=A+C) accordingly to operate the cooling fan 37a. This makes it possible to reduce the noise of the cooling fan and the current consumption by controlling the drive start time of the cooling fan.

[0028] <Second embodiment> FIG. 7 is a timing chart showing an overview of fan drive time control based on print-OFF time in an image forming apparatus according to a second embodiment of the present invention. In FIG. 7, the previous printing end time is time t 1fe Let the current printing time be time t 21 ~t 2fe The fan operation time is set to time t 2fs ~t 2fe At time t 1fe From time t 21 Print OFF time t off (Print off time). The previous print job ended (time t 1fe ), power supply to the fixing heater 25a is terminated, so that no current flows through the AC output control element 26a and the temperature of the element drops. off ) is long, the temperature of the AC output control element 26a drops sufficiently and drops to near room temperature. On the other hand, the previous print end (t 1fe ) to start printing (t 21 ) until the print is turned off (t off When the period is short, the temperature of the AC output control element 26a does not drop completely and remains between room temperature and the upper limit temperature. Last print end (t 1fe ) to start printing (t 21 ) until the print-OFF time t off ) is long, the time t at which the temperature of the AC output control element 26a reaches the upper limit in the current printing is offSince the time when the cooling fan 37a that cools the AC output control element 26a starts to be driven (t 2fs ) slows down. On the other hand, the print-off time t off If t is short, the time to reach the upper limit temperature is short, so the fan start time (t 2fs ) to speed up the process.

[0029] <Graph (part 2)> FIG. 8(a) is a graph (part 2) showing an example of the temperature of the AC output control element when the print-OFF time is different in the image forming apparatus according to the second embodiment of the present invention. That is, FIG. 8(a) shows an example of the temperature of the AC output control element when the print-OFF time is different. The cooling control unit 50a controls the temperature Ts of the AC output control element 26a of the image forming apparatus 1 to be lower than a certain temperature (for example, 25° C.) and the upper limit temperature 150° C. (T top ) (for example, 80% of the upper limit temperature of the AC output control element 26a) is grasped and recorded as a control table 56 in the RAM 15c. <Control table (part 2)> FIG. 8(b) is a diagram (part 2) showing a control table storing an example of the relationship between the temperature and time of the AC output control element in the image forming apparatus according to the second embodiment of the present invention. In the control table 56 shown in FIG. 8(b), the temperature T and the time t are stored in association with each other. Here, the temperature Ts is the temperature of the AC output control element 26a, and the time t is the time when the temperature Ts changes from, for example, 25° C. to the upper limit temperature 150° C. (T top ) (for example, 80% of the upper limit temperature of the AC output control element 26a).

[0030] <Control table (part 3)> FIG. 8(c) is a diagram (part 3) showing a control table storing an example of the relationship between the print-OFF time and the temperature of the AC output control element in the image forming apparatus according to the second embodiment of the present invention. The cooling control unit 50a is configured to 1fe ) to start printing (t 21 ) until the print is turned off (t off )) and the temperature drop characteristics due to the print OFF time (t off ) is associated with the temperature Ts of the AC output control element 26a and recorded as a control table 57 in the RAM 15c.

[0031] The control table 57 shown in FIG. 8C includes the print-OFF time (t off ), and temperature T are stored in association with each other. off ) is the end of the previous print (t 1fe ) to start printing (t 21 ) and temperature Ts is the temperature of AC output control element 26a.

[0032] <Operation of the cooling control unit> (1) When starting printing, the print-off time measurement unit 50b measures the time from the end of the previous print (t 2fe ) to start printing (t 21 ) until the print is turned off (t off )) is measured. (2) The cooling control unit 50a determines the printing OFF time (t off ) is obtained from the control table 57 and estimated. (3) Furthermore, the cooling control unit 50a calculates the upper limit temperature 150° C. (T top ) is obtained from the control table 56 and estimated, and the drive start time (t 2fs ) to delay.

[0033] <Flowchart (part 2)> FIG. 9 is a flowchart (part 2) for explaining the operation of the image forming apparatus according to the second embodiment of the present invention. In the first embodiment, control is performed to set the fan start time by determining whether the input voltage Vac is in a steady state (100 V±α (for example, α=5 V)). In addition, a second embodiment is characterized in that control is performed to set the fan start time by measuring the print OFF time and determining whether the print OFF time is equal to or longer than t1. In addition, since S10, S20, and S70 to S90 in the flowchart shown in FIG. 9 are similar to those in the flowchart shown in FIG. 6, detailed description thereof will be omitted.

[0034] In step S20, the cooling control unit 50a determines whether the input voltage Vac is in a steady state (100 V±α (eg, α=5 V)). If the input voltage Vac is in a steady state (100V±α (eg, α=5V)), the process proceeds to step S121, where the cooling control unit 50a determines whether the print-OFF time is equal to or longer than t1. If the print-OFF time is equal to or longer than t1, that is, if the print-OFF time is sufficiently long (equal to or longer than t1) and the element temperature Ts has dropped sufficiently, the process proceeds to step S122, where the cooling control unit 50a determines the fan start time to be time A, sets the timer 15d to time A, starts the timer 15d, and proceeds to step S70. Thereafter, the process proceeds to steps S70 to S90. Note that A is a positive value.

[0035] If the print-OFF time is not t1 or more, that is, if the print-OFF time is not long enough (less than t1) and the element temperature Ts has not dropped sufficiently, the process proceeds to step S123, where the cooling control unit 50a determines the fan start time to be time AD, sets the timer 15d to time AD, starts the timer 15d, and proceeds to step S70. Thereafter, the process proceeds to steps S70 to S90. Note that A and D are positive values.

[0036] If the input voltage Vac is not in a steady state (100V±α (eg, α=5V)), the process proceeds to step S140, where the cooling control unit 50a determines whether the input voltage Vac is lower than the steady state (Vac<100V-α). If the input voltage Vac is lower than the steady state voltage (Vac<100V-α), the process proceeds to step S141, where the cooling control unit 50a determines whether the print-OFF time is equal to or longer than t1. If the print-OFF time is t1 or more, that is, if the print-OFF time is sufficiently long (t1 or more) and the element temperature Ts has dropped sufficiently, the process proceeds to step S142, where the cooling control unit 50a determines the fan start time to be time (t=AB), sets the timer 15d to time (t=AB), starts the timer 15d, and proceeds to step S70. Thereafter, the process proceeds to steps S70 to S90. Note that A and B are positive values.

[0037] If the print-OFF time is not t1 or more, that is, if the print-OFF time is not long enough (less than t1) and the element temperature Ts has not dropped sufficiently, the process proceeds to step S143, where the cooling control unit 50a determines the fan start time to be time (t=ABD), sets the timer 15d to time (t=ABD), starts the timer 15d, and proceeds to step S70. Thereafter, the process proceeds to steps S70 to S90. Note that A, C, and D are positive values.

[0038] If the input voltage Vac is higher than the steady state voltage (Vac>100V-α), the process proceeds to step S160, where the cooling control unit 50a determines whether the print-OFF time is equal to or longer than t1. If the print-OFF time is equal to or longer than t1, that is, if the print-OFF time is sufficiently long (equal to or longer than t1) and the element temperature Ts has dropped sufficiently, the process proceeds to step S161, where the cooling control unit 50a determines the fan start time to be time (t=A+C), sets the timer 15d to time (t=A+C), starts the timer 15d, and proceeds to step S70. Thereafter, the process proceeds according to steps S70 to S90. Note that A and C are positive values. In this way, when the input voltage Vac is higher than the steady state, the printing OFF time is long enough (t1 or more) and the element temperature Ts has dropped sufficiently, the temperature rise of the AC output control element becomes gradual, so the fan start time can be delayed by (t=A+C) accordingly to operate the cooling fan 37a. This makes it possible to reduce the noise of the cooling fan and the current consumption by controlling the drive start time of the cooling fan.

[0039] If the print-OFF time is not longer than t1, that is, if the print-OFF time is not long enough (less than t1) and the element temperature Ts has not dropped sufficiently, the process proceeds to step S162, where the cooling control unit 50a determines the fan start time to be time (t=A+CD), sets the timer 15d to time (t=A+CD), starts the timer 15d, and proceeds to step S70. Thereafter, the process proceeds to steps S70 to S90. Note that A, C, and D are positive values. In this way, when the input voltage Vac is higher than the steady state, the print-OFF time is not long enough (less than t1) and the element temperature Ts has not dropped sufficiently, the fan start time can be delayed by (t=A+CD) to operate the cooling fan 37a. This makes it possible to reduce the noise of the cooling fan and the current consumption by controlling the drive start time of the cooling fan.

[0040] <Third embodiment> <Graph (part 3)> FIG. 10A is a graph (part 3) illustrating an example of the temperature of the output control element when the environmental temperature is different in the image forming apparatus according to the third embodiment of the present invention. A temperature sensor 39a for measuring the environmental temperature Tk is provided on the side of the image forming apparatus 1. FIG. 10(a) shows the temperature sensor 39a for measuring the environmental temperature Tk when the apparatus is first started or when the apparatus is in a sleep / standby state for a long enough period and the temperature of the apparatus drops to the environmental temperature Tk. top ) is grasped and recorded in the RAM 15c as a control table 58.

[0041] <Control table (part 4)> FIG. 10B shows the temperature range from the environmental temperature Tk to the upper limit temperature 150° C. (T top 4 is a diagram (part 4) showing a control table storing an example of the time t at which the temperature rises to the temperature In the control table 58 shown in FIG. 10B, when the temperature of the image forming apparatus 1 drops to the environmental temperature Tk after the initial startup or after the image forming apparatus 1 has been in a sleep / standby state for a long enough period of time, the temperature T of the AC output control element 26a drops from the environmental temperature Tk to the upper limit temperature 150° C. (T top ) is stored.

[0042] <Operation of the cooling control unit> (1) When starting printing, the cooling control unit 50a obtains the environmental temperature Tk from the temperature sensor 39a. (2) The cooling control unit 50a obtains the temperature Ts of the AC output control element 26a from the temperature sensor 38a. (3) The cooling control unit 50a determines whether or not the temperature Ts of the body (AC output control element 26a) of the image forming apparatus 1 has dropped to the environmental temperature Tk due to a sufficient period of time during initial startup or sleep / standby state. (4) When it is determined that the temperature Ts has dropped to the environmental temperature Tk, the cooling control unit 50a top ) is obtained from the control table 58 and estimated. (5) The cooling control unit 50a adjusts the drive start time (t 2fs ) to delay. Thereby, when the temperature Ts of the AC output control element 26a is lower than the environmental temperature Tk, the cooling control unit 50a can further delay the drive start time of the cooling fan 37a.

[0043] <Flowchart (part 3)> FIG. 11 is a flowchart (part 3) for explaining the operation of the image forming apparatus according to the third embodiment of the present invention. In the first embodiment, the fan start time is controlled by determining whether the input voltage Vac is in a steady state (100V±α (for example, α=5V)). In addition, the third embodiment is characterized in that it includes a temperature sensor 39a that measures the environmental temperature, and the cooling control unit 50a further delays the drive start time of the cooling fan 37a when the environmental temperature measured by the temperature sensor 39a is lower than the steady state temperature Tk. In addition, since S10, S20, and S70 to S90 in the flowchart shown in FIG. 11 are similar to those in the flowchart shown in FIG. 6, detailed description thereof will be omitted.

[0044] In step S20, the cooling control unit 50a determines whether the input voltage Vac is in a steady state (100 V±α (eg, α=5 V)). If the input voltage Vac is in a steady state (100V±α (eg, α=5V)), the process proceeds to step S221, where the cooling control unit 50a determines whether the environmental temperature Tk is within 25±α (eg, α=5° C.). If the environmental temperature Tk is within 25±α, the process proceeds to step S222, where the cooling control unit 50a determines the fan start time to be time A, sets the timer 15d to time A, starts the timer 15d, and proceeds to step S70. Thereafter, the process proceeds to steps S70 to S90. Note that A is a positive value.

[0045] If the environmental temperature Tk is not within 25±α, that is, if the environmental temperature Tk is 25-α or more, the process proceeds to step S223, where the cooling control unit 50a judges whether the environmental temperature Tk is 25-α or less. If the environmental temperature Tk is 25-α or less, the process proceeds to step S224, where the cooling control unit 50a determines the fan start time to be time A+E, sets the timer 15d to time A+E, starts the timer 15d, and proceeds to step S70. Thereafter, the process proceeds to steps S70 to S90. Note that A and E are positive values. When the environmental temperature Tk is low (25° C.-α° C. or lower), the temperature rise time of the AC output control element 26a becomes long, so that the fan start time can be delayed by time E before the fan is operated.

[0046] If the environmental temperature Tk is not equal to or lower than 25-α, the process proceeds to step S225, where the cooling control unit 50a determines the fan start time to be time AF, sets the timer 15d to time AF, starts the timer 15d, and proceeds to step S70. Thereafter, the process proceeds to steps S70 to S90. Note that A and F are positive values. When the environmental temperature Tk is high, the time it takes for the element to reach the set temperature is shortened, so that the fan can be operated earlier by the time F.

[0047] If the input voltage Vac is not in a steady state (100V±α (e.g., α=5V)), that is, if the input voltage Vac is outside the range of the steady state (100V±α (e.g., α=5V)), the process proceeds to step S240, and the cooling control unit 50a determines whether the input voltage Vac is lower than the steady state (Vac<100V-α). If the input voltage Vac is lower than the steady state (Vac<100V-α), the process proceeds to step S241, where the cooling control unit 50a determines whether the environmental temperature Tk is within 25±α (eg, α=5° C.). If the environmental temperature Tk is within 25±α, the process proceeds to step S242, where the cooling control unit 50a determines the fan start time to be time AB, sets the time AB in the timer 15d, starts the timer 15d, and proceeds to step S70. Thereafter, the process proceeds to steps S70 to S90. Note that A and B are positive values.

[0048] If the environmental temperature Tk is not within 25±α, the process proceeds to step S243, where the cooling control unit 50a judges whether the environmental temperature Tk is 25-α or less. If the environmental temperature Tk is 25-α or less, the process proceeds to step S244, where the cooling control unit 50a determines the fan start time to be time A-B+E, sets the timer 15d to time A-B+E, starts the timer 15d, and proceeds to step S70. Thereafter, the process proceeds to steps S70 to S90. Note that A, B, and E are positive values. When the environmental temperature Tk is low (25° C.-α° C. or lower), the temperature rise time of the AC output control element 26a becomes long, so that the fan start time can be delayed by time E before the fan is operated.

[0049] If the environmental temperature Tk is not equal to or less than 25-α, that is, if the environmental temperature Tk is equal to or greater than 25-α, the process proceeds to step S245, where the cooling control unit 50a determines the fan start time to be time ABF, sets the timer 15d to time ABF, starts the timer 15d, and proceeds to step S70. Thereafter, the process proceeds to steps S70 to S90. Note that A, B, and F are positive values. When the environmental temperature Tk is high, the time it takes for the element to reach the set temperature is shortened, so that the fan can be operated earlier by the time F.

[0050] If the input voltage Vac is not lower than the steady state (Vac<100V-α), i.e., if the input voltage Vac is higher than the steady state (Vac>100V-α), the process proceeds to step S260, and the cooling control unit 50a determines whether the environmental temperature Tk is within 25±α (for example, α=5°C). If the environmental temperature Tk is within 25±α, the process proceeds to step S261, where the cooling control unit 50a determines the fan start time to be time A+C, sets the timer 15d to time A+C, starts the timer 15d, and proceeds to step S70. Thereafter, the process proceeds to steps S70 to S90. Note that A and B are positive values.

[0051] If the environmental temperature Tk is not within 25±α, the process proceeds to step S262, where the cooling control unit 50a determines whether the environmental temperature Tk is equal to or lower than 25−α. If the environmental temperature Tk is equal to or lower than 25-α, the process proceeds to step S263, where the cooling control unit 50a determines the fan start time to be time A+C+E, sets the timer 15d to time A+C+E, starts the timer 15d, and proceeds to step S70. Thereafter, the process proceeds to steps S70 to S90. Note that A, C, and E are positive values. When the environmental temperature Tk is low (25°C-α°C or lower), the temperature rise time of the AC output control element 26a becomes long, so the fan start time can be delayed by the time E to operate the fan. In this way, by controlling the drive start time of the cooling fan, the noise of the cooling fan can be reduced and the current consumption can be reduced.

[0052] If the environmental temperature Tk is not equal to or less than 25-α, that is, if the environmental temperature Tk is equal to or greater than 25-α, the process proceeds to step S264, where the cooling control unit 50a determines the fan start time to be time A+CF, sets the timer 15d to time A+CF, starts the timer 15d, and proceeds to step S70. Thereafter, the process proceeds to steps S70 to S90. Note that A, C, and F are positive values. When the environmental temperature Tk is high, the time it takes for the element to reach the set temperature is shortened, so that the fan can be operated earlier by the time F.

[0053] <Summary of the functions and effects of the embodiment> <First aspect> The image forming apparatus 1 of this embodiment includes a fixing heater 25a, a temperature control unit 31a that controls the heater temperature by controlling the power supplied from the AC power source 12 to the fixing heater 25a using an AC output control element 26a, a cooling fan 37a that suppresses an increase in temperature of the AC output control element 26a, and a drive unit 36a that drives the cooling fan 37a. The image forming apparatus 1 includes an AC voltage detection unit 28a that detects an input voltage Vac of the AC power source 12, and a cooling control unit 50a that controls the on / off of the drive unit 36a in response to a level fluctuation of the input voltage Vac in order to maintain the temperature Ts of the AC output control element 26a within an allowable temperature range. The cooling control unit 50a determines a drive start time t of the cooling fan 37a based on the input voltage Vac of the AC power source 12. 1fs The method is characterized in that: According to this embodiment, the cooling control unit 50a determines the drive start time t of the cooling fan 37a based on the input voltage Vac of the AC power supply 12. 1fs By determining the time when the cooling fan starts to be driven, the noise of the cooling fan can be reduced and the current consumption can be reduced.

[0054] <Second aspect> In the image forming apparatus 1 of this embodiment, the heater is a fixing heater 25a used for image formation. According to this embodiment, even if the heater is the fixing heater 25a used for image formation, power is supplied from the AC power source 12 to the fixing heater 25a via the AC output control element 26a, so that the increase in temperature of the AC output control element 26a can be suppressed by the cooling fan 37a, and further, by controlling the drive start time of the cooling fan, the noise of the cooling fan can be reduced and the current consumption can be reduced.

[0055] <Third aspect> The cooling control unit 50a of this embodiment is characterized in that, when the input voltage Vac of the AC power supply 12 is higher than that in the steady state, the driving start time of the cooling fan 37a is delayed. According to this embodiment, when the input voltage Vac of the AC power supply 12 is higher than that in the steady state, the cooling control unit 50a delays the drive start time of the cooling fan 37a by (t=A+C), thereby reducing the noise of the cooling fan 37a and the current consumption.

[0056] <Fourth aspect> In the image forming apparatus 1 of this embodiment, the printing off time t off The cooling control unit 50a is provided with a printing-off time measurement unit 50b that measures the printing-off time t off The driving start time of the cooling fan 37a is determined based on the above. According to this embodiment, the cooling control unit 50a controls the printing off time t off By determining the drive start time of the cooling fan 37a based on the above, the drive start time of the cooling fan 37a can be controlled to reduce the noise of the cooling fan 37a and the current consumption. For example, the printing off time t off Even if the time is short and preheating still remains, the cooling fan 37a can be operated at the optimum start timing, reducing noise and current consumption.

[0057] <Fifth aspect> The image forming apparatus 1 of this embodiment is equipped with a temperature sensor 39a that measures the environmental temperature Tk, and the cooling control unit 50a is characterized in that when the environmental temperature Tk measured by the temperature sensor 39a is lower than the steady-state temperature, the cooling control unit 50a further delays the start time of driving the cooling fan 37a. According to this embodiment, when the environmental temperature Tk measured by the temperature sensor 39a is lower than the temperature in the steady state, the cooling control unit 50a can further delay the drive start time of the cooling fan 37a.

[0058] <Sixth aspect> The image forming apparatus 1 of this embodiment includes a temperature sensor 38a that measures a temperature Ts of the AC output control element 26a, and a temperature sensor 39a that measures an external environmental temperature Tk, and is characterized in that the cooling control unit 50a further delays the start time of driving the cooling fan 37a when the temperature Ts of the AC output control element 26a is lower than the environmental temperature Tk. According to this embodiment, when the temperature Ts of the AC output control element 26a is lower than the environmental temperature Tk, the cooling control unit 50a can further delay the drive start time of the cooling fan 37a. [Explanation of symbols]

[0059] 5...image forming section, 6...photosensitive drum, 7...developing section, 8...conveyor belt, 9...fixing section, 12...AC power supply, 14...control board, 15a...CPU, 15b...ROM, 15c...RAM, 15d...timer, 25...halogen heater, 25a...fixing heater, 26...TRIAC, 26a...AC output control element, 27...TRIAC control signal, 28...AC voltage detection circuit, 28a...AC voltage detection section, 31a...temperature control section, 35a...DC power supply, 36a...drive section, 37a...cooling fan, 38a...temperature sensor, 39a...temperature sensor, 50a...cooling control section, 50b...print off time measurement section, 51a...temperature control section, 55...control table, 56...control table, 57...control table, 58...control table [Prior art documents] [Patent documents]

[0060] [Patent Document 1] JP 2009-180909 A

Claims

1. A heater and a temperature control unit that controls the power supplied from an AC power source to the heater by an AC output control element to control the heater temperature; a cooling fan for suppressing an increase in temperature of the AC output control element; A drive unit that drives the cooling fan, an AC voltage detection unit that detects an input voltage of the AC power source; a cooling control unit that controls on / off of the drive unit in response to a level fluctuation of the input voltage in order to maintain a temperature of the AC output control element within an allowable temperature range; The device, wherein the cooling control unit determines a time to start driving the cooling fan based on an input voltage of the AC power supply.

2. 2. The apparatus according to claim 1, wherein the heater is a fixing heater used in image formation.

3. 2. The device according to claim 1, wherein the cooling control unit delays the drive start time of the cooling fan when the input voltage of the AC power supply is higher than that in a steady state.

4. a print-off time measuring unit for measuring a print-off time from the end of a previous print to the start of a current print, The apparatus according to claim 2 , wherein the cooling control unit determines the time to start driving the cooling fan based on the printing off time.

5. An environmental temperature sensor that measures an external environmental temperature; The device according to claim 1 , wherein the cooling control unit further delays the start time of driving the cooling fan when the environmental temperature is lower than a steady-state temperature.

6. a temperature sensor for measuring a temperature of the AC output control element; An environmental temperature sensor that measures an external environmental temperature; 2. The device according to claim 1, wherein the cooling control unit further delays the drive start time of the cooling fan when the temperature of the AC output control element is lower than the environmental temperature.

Images