JP2022097934A - Image forming apparatus - Google Patents

Abstract

To solve the problem in which: executing printing from a standby state requires execution of warm-up from a standby temperature to a print startable temperature, which extends the time required for printing by the time of execution of warm-up.SOLUTION: An image forming apparatus has: a fuser 70 that includes a halogen heater 111 and fixes a toner image; and control units (201, 101, 102) that control a fixing temperature. The control units control the temperature of the halogen heater 111 so that the temperature of the fuser approaches a target temperature, set the target temperature to a preset temperature in a printing operation mode, or a high-temperature standby temperature lower than the preset temperature in the printing operation mode in a printing standby state, or a low-temperature standby temperature lower than the high-temperature standby temperature in the printing standby state, and reduce the minimum on-time during which the halogen heater 111 is energized at a time in the high-temperature standby temperature state than the minimum on-time during which the halogen heater 111 is energized at a time in the low-temperature standby temperature state.SELECTED DRAWING: Figure 8

Description

The present invention relates to a method for controlling the temperature of a fixing device in an image forming device.

Conventionally, an image forming apparatus has been proposed in which the fixing temperature of the fixing device is set to be equal to or lower than the print start lower limit temperature (the lower limit of the printable temperature) when the power is turned on and the printing is completed. (See, for example, Patent Document 1).

JP-A-2017-116635 (Page 8, FIG. 4)

However, in the above-mentioned conventional configuration, the heat generating portion may be heavily consumed in the standby state, and the life of the fixing device may be shortened.

The image forming apparatus according to the present invention is an image forming apparatus for printing.
An image forming unit that transfers a developer image to a recording medium, a fuser that generates heat when energized, and a fuser that fixes the developer image, and a control unit that controls the fuser temperature of the fuser. And have
The control unit controls the temperature of the heat generating unit so that the fuser temperature approaches the target temperature, and sets the target temperature at the set temperature in the print operation mode or in the print operation mode during the print standby. The first temperature is set to a temperature lower than the temperature, or the second temperature is set to a second temperature lower than the first temperature when waiting for printing, and the control unit energizes the heat generating unit once in the first temperature state. It is characterized in that the minimum on-time is shorter than the minimum on-time for energizing the heat generating portion once in the second temperature state.

According to the present invention, the consumption of the heat generating portion can be suppressed in the standby state, and the life of the fixing device can be shortened.

It is a main part block diagram which shows the main part structure of Embodiment 1 of the image forming apparatus based on this invention. It is a block diagram which shows the main part structure of the drive control system of an image forming apparatus. It is the main part block diagram which shows the internal structure of the fuser schematicly, (a) is the front view seen from the entrance side of the paper passing direction which receives a recording paper, (b) is the left side view. It is explanatory drawing of the halogen heater. It is a circuit diagram which shows the energization drive control part of the halogen heater of a fuser. It is a state transition diagram which shows the flow of the fixing temperature control of Embodiment 1 by this invention which has a high temperature standby state. It is an image diagram of each waveform of a heater on signal and the surface temperature Th of a heat roller read by a thermopile in a printing operation mode, a high temperature standby state, and a low temperature standby state. It is a flowchart which shows the flow of the fuser temperature control by a print control part. The heater on signal and the fuser temperature Th when the target temperature is set to the high temperature standby temperature A, the minimum heater on time is set to 2 seconds, and the temperature is controlled so that the fuser temperature Th approaches the target temperature by the PID control method. It is a waveform diagram of. The heater on signal and fuser when the target temperature is set to the high temperature standby temperature A, the minimum heater on time is set to 0.1 seconds, and the temperature of the fuser temperature Th is controlled to approach the target temperature by the PID control method. It is a waveform diagram with temperature Th. It is a graph which showed the power consumption of the whole image forming apparatus when the temperature of the fuser was controlled by setting the minimum heater on time to 2 seconds and 0.1 second, respectively. It is an image diagram showing the temporal change of the temperature of the valve of the halogen heater driven by these heater on signals having different heater on times and the heater on signals in the low temperature standby state, and the heater minimum in (b). The on time is set longer than the minimum heater on time in (a). It is an image diagram which shows the relationship between the temperature of a valve and the life of a halogen heater.

Embodiment 1.
FIG. 1 is a main part configuration diagram showing a main part configuration of the first embodiment of the image forming apparatus based on the present invention.

As shown in the figure, the image forming apparatus 1 includes, for example, a configuration as a tandem type color electrophotographic printer, and the paper feed cassette 10 has a recording paper 40 as a recording medium laminated therein, and the image forming apparatus 1 It is detachably attached to. The pickup roller 21 constitutes a paper feed unit 20 together with a paper feed roller 22 and a separation roller 23 arranged in pairs in contact with each other. The pickup roller 21 and the paper feed roller 22 are rotationally driven by the paper feed motor 202 (see FIG. 2), and the separation roller 23 generates torque in the counter-rotation direction by a torque generating means (not shown).

Therefore, the pickup roller 21 pulls out the uppermost recording paper 40 that comes into contact with the paper cassette 10, and the paper feed roller 22 and the separation roller 23 are, for example, when a plurality of recording papers 40 are pulled out at the same time. Also, the recording sheets 40 are sequentially fed to the transport path one by one.

A resist roller 31 and a transport roller 32 are arranged in this order in a transport path on the downstream side of the paper feed unit 20 in the transport direction of the recording paper 40. The resist roller 31 is paired with a traveling pressure roller 33 that pressurizes the resist roller 31 to generate a transport force, and the transport roller 32 pressurizes the transport roller 32 to generate a transport force. It is paired with 34. The roller pair of the resist roller 31 forces the recording paper 40 to skew, and the roller pair of the transport roller 32 feeds the recording paper 40 to the image forming unit via the writing sensor 35.

The image forming unit consists of four developing units 50K, 50Y, 50M, 50C (referred to as 50 when it is not necessary to distinguish them) and four LED heads 57K, 57Y, 57M, 57C, which are detachably arranged in series. (Indicated as 57 if it is not particularly necessary to distinguish), and a transfer unit 60 that transfers the toner development formed by the developing unit 50 to the upper surface of the recording paper 40 by Coulomb force. The four developing units 50 arranged in series are all structurally the same, and the colors of the toner used as the developing agent, that is, black (K), yellow (Y), magenta (M), and cyan (M). Only the operation timing differs from C). Here, in order from the upstream side in the paper transport direction, a development unit 50K for black (K), a development unit 50Y for yellow (Y), a development unit 50M for magenta (M), and a development unit for cyan (C). 50C is arranged.

Therefore, here, the internal configuration of the black (K) developing unit 50K will be described below as a representative.

The developing unit 50K includes a detachable toner cartridge 51K, and further, a photoconductor drum 52K that supports toner development, a charging roller 53 that charges the surface of the photoconductor drum 52K, and an LED head 57K that exposes the photoconductor drum 52K. A developing roller 54 that forms toner development by frictional charging on an electrostatic latent image formed on a charged surface, a toner supply roller 55 that supplies toner to the developing roller 54, and residual toner that remains on the surface of the photoconductor drum 52K after transfer. It is equipped with a cleaning blade 56 or the like that scrapes off the toner. Power is transmitted from the ID motor 204 (see FIG. 2) to the drums and rollers used in each developing unit 50 via gears and the like.

The transfer unit 60 is paired with a transfer belt 61 that electrostatically attracts the recording paper 40 and conveys it in the direction of arrow A, a drive roller 62 that drives the transfer belt 61, and a drive roller 62, and stretches the transfer belt 61. The tension rollers 63 and the photoconductor drums 52K, 52Y, 52M, and 52C of the developing unit 50 (referred to as 52 when it is not necessary to distinguish them) are arranged so as to face each other and press contact with each other to record toner development. It is provided with transfer rollers 67K, 67Y, 67M, 67C (referred to as 67 when it is not necessary to distinguish them) and the like, which apply a voltage to transfer to 40. The drive roller 62 is rotationally driven by a belt motor 203 (see FIG. 2).

The development unit 50 and the transfer belt 61 are driven in synchronization with each other, and the toner development of each color is sequentially superimposed and transferred on the recording paper 40 electrostatically adsorbed on the transfer belt 61. The recording paper 40 to which the toner development of each color is transferred by the image forming unit in this way is sent to the fixing device 70 that fuses the toner development to the recording paper by heat and pressure.

The fuser 70 is provided with a halogen heater 111 as a heat generating portion, which will be described later, and is in contact with the recording paper 40 from above, and is pressed against the heat roller 71 and the heat roller 71 which are driven by the fixing motor 205 (see FIG. 2) and rotate. The arranged backup roller 72 is provided, and heating and pressurization are executed while the recording paper 40 is conveyed in the arrow B direction (paper-passing direction) by the rotating heated heat roller 71 and the backup roller 72 that follows it. , The toner adhering to the recording paper 40 is fused to fix the toner image on the recording paper 40. The fuser 70 will be described in detail later.

Discharge sensors 36 and discharge roller pairs 37, 38 are sequentially arranged in the transport path on the downstream side of the fuser 70 in the transport direction of the recording paper 40, and the fixed recording paper 40 discharged from the fuser 70 is placed. It is conveyed along the route and discharged to the discharge tray 39.

The writing sensor 35 is a sensor that detects the presence or absence of the recording paper 40, and the detection signal of the writing sensor 35 serves as a reference for the exposure timing of the LED head 57 and the timing of applying a high voltage to the transfer roller 67. Further, the discharge sensor 36 is also a sensor for detecting the presence / absence of the recording paper 40, and the detection signal of the discharge sensor 36 serves as a reference for whether or not a series of image forming processes for the recording paper 40 is completed.

FIG. 2 is a block diagram showing a configuration of a main part of the drive control system of the image forming apparatus 1.

In the figure, the print control unit 201 drives and controls the entire printing operation of the image forming apparatus 1, and notifies the fixing control unit 101 of the width information of the recording paper 40 and printing conditions such as thickness and width. Further, a drive for driving a stepping motor or a DC motor, a paper feed motor 202, and a transfer belt 61 for instructing a printing operation mode and a target temperature according to a standby state, which will be described later, to feed and convey the recording paper 40. A stepping motor or a DC motor for driving the roller 62 to rotate, a belt motor 203, a brushless DC motor for driving each rotating portion of each developing unit 50, an ID motor 204, a fuser 70, and a discharge roller pair 37, 38. The fixing motor 205, which is a brushless DC motor to be driven, is rotationally driven according to each drive timing.

Further, for the LED head 57, for the high voltage circuit 206 that controls the exposure timing of each LED head 57 and generates a high voltage for charging and development performed by the developing unit 50 and transfer by the transfer unit 60. , Command the output timing of each voltage. The rotary drive of the fuser 70 is realized by decelerating the driving force of the fixing motor 205 via a gear train (not shown) and then transmitting the driving force to the heat roller 71.

FIG. 3 is a configuration diagram of a main part schematically showing the internal configuration of the fuser 70, and FIG. 3A is a front view seen from the paper-passing direction entrance side for receiving the recording paper 40. b) is the left side view. The fuser 70 may be specified on the front (front side), rear (back side), left and right sides when the recording paper 40 is carried in, that is, from the arrow B direction (paper passing direction).

In the fuser 70, the heat roller 71 and the backup roller 72 are arranged to face each other so as to sandwich the recording paper 40 conveyed from the transfer belt 61 to form a nip portion, and are transferred onto the recording paper 40. The toner image attached by a weak electrostatic force is melted by heat and then fixed on the recording paper 40 by the pressure of the backup roller 72.

The heat roller 71 is a tubular roller made of a base material such as aluminum or stainless steel, and is represented by an elastic layer made of silicone rubber, PTFE (polytetrafluoroethylene), and PFA (perfluoroalkoxy alkane). It has a structure in which a surface layer made of a fluororesin coating or a tube obtained by processing them is overlapped. The heat roller 71 includes a halogen heater 111 inside. Heat can be generated by supplying electric power to the halogen heater 111.

A thermopile 112, which is a temperature sensor for detecting the temperature of the surface of the heat roller 71, is installed outside the heat roller 71. The thermopile 112 is a non-contact temperature sensor that is installed so as to face the side surface on the entrance side in the paper passing direction and receives infrared rays emitted from the surface of the heat roller 71 and converts them into temperature. The installation position of the thermopile 112 in the longitudinal direction of the heat roller 71 is the central portion of the heat roller 71.

FIG. 4 is an explanatory diagram of the halogen heater 111. The halogen heater 111 encloses halogen in a bulb 111a made of a glass tube, and passes the filament 111b connected to the lead wire 111c in the longitudinal direction thereof. Further, the halogen heater 111 can energize the filament 111b from the lead wire 111c without leaking the halogen enclosed in the valve 111a. The lead wire 111c is connected to a commercial power supply 104 and a triac 103 (see FIG. 5), which will be described later.

FIG. 5 is a circuit diagram showing an energization drive control unit of the halogen heater 111 of the fuser 70.

As shown in the circuit diagram, the temperature information detected by the thermopile 112 is transmitted to the fixing control unit 101. One electrode of the halogen heater 111 is connected to one terminal of the commercial power supply 104, and the other electrode is connected to one electrode of the triac 103. The other electrode of the triac 103 is connected to the other electrode of the commercial power supply 104, and the gate terminal of the triac 103 is connected to the drive terminal 102a of the triac drive circuit 102. The fixing control unit 101 transmits the heater on signal 106 to the input terminal 102b of the triac drive circuit 102.

The triac drive circuit 102 conducts both electrodes of the triac 103 when the input heater on signal 106 is on (High state), and insulates both electrodes of the triac 103 when it is off (Low state). Drive control. Here, applying a commercial power source to the halogen heater 111 may be referred to as energization. The print control unit 201, the fixing control unit 101, and the triac drive circuit 102 correspond to the control unit.

In the above configuration, the energization control method of the halogen heater 111 of the fuser 70 performed by the fixing control unit 101 will be described, but before that, the problems to be solved by the fixing device according to the present embodiment will be described.

In the normal fixing control described as a comparative example, when the power is turned on, the surface temperature of the heat roller 71 read by the thermopile 112 is a low temperature standby temperature equal to or lower than the printing start lower limit temperature until a predetermined time elapses or a printing request is received. It becomes a low temperature standby state controlled to maintain, and similarly, it becomes this low temperature standby state when printing is completed. Further, in the low temperature standby state, when the print request is not received and a predetermined time elapses, the sleep state is set in which the temperature is not controlled.

In this case, even if the printing operation mode is entered, in order to print from the low temperature standby state, it is necessary to warm up from the low temperature standby temperature to the print start lower limit temperature at which printing is possible. There was a problem that it would be long. The fuser 70 of the present embodiment is temperature controlled in order to avoid these problems.

FIG. 6 is a state transition diagram showing a flow of fixing temperature control according to the first embodiment according to the present invention, which has a high temperature standby state. The state transition of the fixing control having the high temperature standby state will be described with reference to this state transition diagram.

In the fixing control having a high temperature standby state, when the power is turned on, the surface temperature Th of the heat roller 71 read by the thermopile 112 is equal to or higher than the print start lower limit temperature or lower than the print set temperature until a certain time elapses or a print request is received. Maintains a high temperature standby state (ST101) controlled by the temperature of. Similarly, when the printing process in the printing operation mode (ST103) is completed, the high temperature standby state (ST101) is set.

In the high temperature standby state (ST101), if a predetermined time elapses without receiving a print request, the low temperature standby state (ST102) controlled at a temperature equal to or lower than the print start lower limit temperature is reached. If a predetermined time elapses without receiving a print request in the low temperature standby state (ST102), the halogen heater 111 is not heated to sleep (ST104) without temperature control. Hereinafter, the fixing temperature control according to the first embodiment of the present invention will be further described.

FIG. 7 is an image diagram of each waveform of the heater on signal 106 and the surface temperature Th of the heat roller 71 read by the thermopile 112 in the printing operation mode, the high temperature standby state, and the low temperature standby state. Here, a temperature control method by the fixing control unit 101 for bringing the surface temperature Th closer to the target temperature will be briefly described.

The fixing control unit 101 performs a calculation by, for example, a PID (Proportional Integral Differential) control method based on the difference between the surface temperature Th of the heat roller 71 read by the thermopile 112 and the target temperature instructed by the print control unit 201. It is performed every 100 msec, which is one control cycle, and the duty value (n) of the heater-on signal 106 is obtained.

The duty value (n) is calculated in the range of 1% to 100%. Here, the larger the duty value (n), the higher the ratio of the on (High state) to the off (Low state) in the heater on signal 106. It is set to be.

The image diagram of FIG. 7 shows the print set temperature (170 ° C.), which is the target temperature in the print operation mode, and the high temperature standby temperature as the first temperature, which is the target temperature in the high temperature standby state, set by the print control unit 201. The waveforms of the surface temperature Th of the heat roller 71 and the heater-on signal 106 read by the thermopile 112 with respect to (155 ° C.) and the low temperature standby temperature (120 ° C.) as the second temperature which is the target temperature in the low temperature standby state are schematically shown. It is shown in.

As shown in the figure, the heater control of the halogen heater 111 by the print control unit 201 and the fixing control unit 101 is turned on when the surface temperature Th is significantly deviated from the target temperature toward the lower side (as shown in the figure). (High state), when the surface temperature Th is significantly deviated from the target temperature to the higher side, it is turned off (Low state), and as the temperature to be maintained becomes higher, it is turned on (High state) with respect to off (Low state). The ratio of is controlled to be high. However, as will be described later, the minimum on-time is controlled to be longer in the low temperature standby state than in the high temperature standby state. It should be noted that each waveform in the figure is an image diagram and is not accurate.

FIG. 8 is a flowchart showing the flow of the fuser temperature control by the print control unit 201.
The flow of the fuser temperature control by the print control unit 201 according to the present invention will be described with reference to the flowchart.

When the power of the image forming apparatus 1 is turned on (step S101), the print control unit 201 immediately shifts to the high temperature standby state (step S102), and the surface temperature Th of the heat roller 71 read by the thermopile 112 (hereinafter, the fixing device). The high temperature standby temperature A, which is the target temperature of (sometimes referred to as temperature), is set. Along with this, the fixing control unit 101 controls the temperature of the fixing device temperature Th by the PID control method so as to approach the high temperature standby temperature A which is the target temperature.

Here, the high temperature standby temperature A, which is the target temperature, is
Printing set temperature (170 ° C)> High temperature standby temperature A ≥ Printing start lower limit temperature (152 ° C)
It is set in the range of, but here it is set to 155 ° C.
The print set temperature is a temperature set as a target temperature of the print operation mode, and the print start lower limit temperature is the minimum required temperature that must be reached when printing is executed.

If there is a print request (step S103, Yes, step S105, No) within the first elapsed time (60 seconds in this case) after shifting to the high temperature standby state, the printing operation mode is shifted. When the first elapsed time elapses without a print request (step 103, No, step 105, Yes) after shifting to the high temperature standby state, the print control unit 201 shifts to the low temperature standby state (step S106). ..

In this low temperature standby state, the low temperature standby temperature B is set as the target temperature of the fuser temperature Th read by the thermopile 112. Along with this, the fixing control unit 101 controls the temperature of the fixing device temperature Th by the PID control method so as to approach the low temperature standby temperature B which is the target temperature.

The low temperature standby temperature B, which is the target temperature here, is
Lower limit temperature for printing start (152 ° C here)> Low temperature standby temperature B
That is, it is set to be lower than the print start lower limit temperature, but here it is set to 120 ° C.

If there is a print request within the second elapsed time (180 seconds in this case) after shifting to the low temperature standby state (step S107, Yes, step S108, No), the printing operation mode is shifted (step S104). When the second elapsed time elapses without a print request (step 107, No, step 108, Yes), the print control unit 201 shifts to the sleep state (step S109).

If there is a print request (step S110, Yes) after shifting to the sleep state in which the halogen heater 111 is not heated without temperature control, the print operation mode is entered (step S104), and there is no print request (step S104). The sleep state is maintained in steps S110 and No).

As described above, when a print request is made in the high temperature standby state, the low temperature standby state, and the sleep state, the print operation mode (step S104) is immediately entered, and the high temperature standby state is reached when printing in the print operation mode is completed. The process proceeds to (step S102). After shifting to the high temperature standby state, the above processing process is repeated.

In the print operation mode in step S103, the target temperature is set to the print set temperature (here, 170 ° C.), and the fuser temperature Th is controlled to approach the print set temperature, but the fuser temperature Th is printed. Printing is not executed unless the lower start temperature (here, 152 ° C.) is reached. Therefore, for example, even if there is a printing request in the high temperature standby state immediately after the power is turned on and the printing operation mode is entered, the fuser temperature Th rises from room temperature, and as shown in FIG. 7, the printing start lower limit temperature (152 ° C.) ) Is not executed.

In the high temperature standby state after printing is completed or after the fuser temperature Th reaches the high temperature standby temperature A (here, 155 ° C.) in the high temperature standby state after the power is turned on, the fuser temperature Th is the lower limit printing start temperature. Since the state exceeding (here, 152 ° C.) is maintained, when a print request is made in this high temperature standby state and the print operation mode is entered, printing is immediately executed.

Next, for example, the setting of the heater minimum on time of the heater on signal 106 generated by the PID control method will be described.

FIG. 9 shows a case where the target temperature is set to the high temperature standby temperature A (155 ° C.), the minimum heater on time is set to 2 seconds, and the temperature is controlled so that the fuser temperature Th approaches the target temperature by the PID control method. It is a waveform diagram of the heater on signal 106 and the fuser temperature Th read by the thermopile 112. FIG. 10 also sets the target temperature to the high temperature standby temperature A (155 ° C.) and sets the minimum heater on time to 0.1 seconds. It is a waveform diagram of the heater-on signal 106 and the fuser temperature Th when the temperature is controlled so that the fuser temperature Th is brought closer to the target temperature by the PID control method.

The minimum heater on time referred to here is the minimum on (High state) time of the heater on signal 106, and when the minimum on time of the heater is 2 seconds, once it is turned on (High state), it is at least 2 seconds. Controls to maintain on (High state). In other words, in the case of temperature control by repeating on / off, the minimum time in one energization time from turning off to on and then switching from on to off is called the heater minimum on time.

As shown in FIG. 9, when the minimum heater on time is set to 2 seconds, the temperature rises more than necessary within 2 seconds, and on average, it is higher than the high temperature standby temperature A (155 ° C.), which is the target temperature. It will change in the state. On the other hand, as shown in FIG. 10, when the minimum heater on time is set to 0.1 second, it is possible to perform precise temperature control with a faster response, and it is possible to maintain a state asymptotic to the target temperature.

FIG. 11 is a graph showing the power consumption of the entire image forming apparatus when the temperature of the fuser 70 is controlled by setting the minimum heater on time to 2 seconds and 0.1 seconds, respectively. As shown in the figure, the power consumption when the heater minimum on time is 0.1 seconds (86.) With respect to the power consumption when the heater minimum on time is 2 seconds (106.8 [Wh]). The ratio of 4 [Wh]) was about 80%. The reason why the power consumption is suppressed in this way is that the shorter the minimum heater on time during control, the finer the temperature control of the heater becomes, and the energy for heating above the target temperature is suppressed. From these results, it can be seen that the power consumption of the entire image forming apparatus can be suppressed by shortening the minimum heater on time.

By the way, in the low temperature standby state, the minimum heater on time cannot be shortened as in the high temperature standby state. This is because if the minimum heater on time is shortened at the temperature of the low temperature standby state, the temperature may be maintained below the appropriate valve temperature, which shortens the life of the halogen heater (see: JP-A-2004-342417). ..

FIG. 12 is an image diagram showing a temporal change in the temperature of the valve 111a of the halogen heater 111 driven by the heater on signals having different minimum heater on times and the heater on signals in the low temperature standby state. The minimum heater on time in FIG. 3B is set longer than the minimum heater on time in FIG. 3A. Tb is the lower limit of the appropriate valve temperature.

As is clear from FIG. 12, when the heater is driven by a heater on signal having a shorter minimum heater on time, the temperature of the valve 111a of the halogen heater 111 may be maintained below the lower limit value Tb of the appropriate valve temperature. Therefore, when the minimum heater on time is 2 seconds, even if the average temperature of the valve 111a can be maintained at an appropriate valve temperature (lower limit value Tb or more) as shown in FIG. In the case of 0.1 seconds, the average temperature of the valve 111a may be maintained below the lower limit value Tb of the appropriate valve temperature as shown in FIG.

FIG. 13 is an image diagram showing the relationship between the temperature of the valve 111a and the life of the halogen heater 111, and the life when used at an appropriate valve temperature is Lb. As shown in the figure, when the valve temperature is used below Tb, the life of the halogen heater 111 is shorter than that of Lb.

From the above, in order to prolong the life of the halogen heater 111 and realize precise temperature control with quick response in the high temperature standby state, the minimum heater on time of the heater on signal in the high temperature standby state is set to low temperature standby. It is necessary to set it shorter than in the state, and in the present embodiment, the minimum heater on time of the heater on signal in the high temperature standby state and the printing operation mode is set to 0.1 second, and the heater of the heater on signal in the low temperature standby state is set. The minimum on-time is 2.0 seconds.

As described above, according to the image forming apparatus of the first embodiment, when a printing instruction is given in a high temperature standby state, printing is immediately executed without warming up, so that printing can be performed efficiently. Further, it is possible to achieve both the long life of the halogen heater 111 and the suppression of unnecessary power consumption by appropriate temperature control in the high temperature standby state.

In the above-described embodiment, an example in which the present invention is adopted as an image forming apparatus as a color printer is shown, but the present invention is not limited to this, and the copier, the facsimile, and the MFP provided with a fuser. It can also be used for image processing devices such as. Further, although the color printer has been described, it may be a monochrome printer.

1 Image forming device, 10 Paper cassette, 20 Paper feed unit, 21 Pickup roller, 22 Paper feed roller, 23 Separation roller, 31 Resist roller, 32 Conveyor roller, 33 Pressure roller, 34 Pressure roller, 35 Write sensor, 36 Discharge Sensor, 37 discharge roller pair, 38 discharge roller pair, 39 discharge tray, 40 recording paper, 50 development unit, 51 toner cartridge, 52 photoconductor drum, 53 charging roller, 54 development roller, 55 toner supply roller, 56 cleaning blade, 57 LED head, 60 transfer unit, 61 transfer belt, 62 drive roller, 63 tension roller, 67 transfer roller, 70 fuser, 71 heat roller, 72 backup roller, 101 anchoring control unit, 102 triac drive circuit, 102a drive terminal, 102b input terminal, 103 triac, 104 commercial power supply, 106 heater on signal, 111 halogen heater, 111a valve, 111b filament, 111c lead wire, 112 thermopile, 201 print control unit, 202 paper feed motor, 203 belt motor, 204 ID motor, 205 anchoring motor, 206 high pressure circuit.

Claims (4)

In an image forming apparatus that prints
An image forming unit that transfers a developer image to a recording medium,
A fuser having a heat generating portion that generates heat when energized and fixing the developer image, and a fuser.
It has a control unit that controls the fuser temperature of the fuser.
The control unit controls the temperature of the heat generating unit so that the fuser temperature approaches the target temperature, and sets the target temperature at the set temperature in the print operation mode or in the print operation mode during the print standby. Set to a first temperature lower than the temperature, or a second temperature lower than the first temperature when waiting for printing.
The control unit is characterized in that the minimum on-time for energizing the heat-generating unit once in the first temperature state is shorter than the minimum on-time for energizing the heat-generating unit once in the second temperature state. Image forming device. The image forming apparatus according to claim 1, wherein the first temperature is equal to or higher than a printable start temperature, and the second temperature is lower than the print start temperature. The control unit is characterized in that, after the power to the image forming apparatus is turned on or after the printing is completed, the target temperature is set to the high temperature standby temperature at the high temperature standby temperature. 2. The image forming apparatus according to 2. The image forming apparatus according to any one of claims 1 to 3, wherein the heat generating portion is a halogen heater.

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