JP2017032774A - Image forming apparatus, program, and control method for image forming apparatus - Google Patents

Abstract

An object of the present invention is to suppress a large drop in the output of a heater when a recording sheet is supplied to a fixing device, and to enable good fixing from the first recording sheet. Kind Code: A1 An image forming apparatus has an image forming section for forming a developer image on a recording sheet, a pickup roller for supplying the recording sheet to the image forming section, a heater and a temperature detecting member. A fixing device that heats the sent recording sheet, and a control unit that controls the heater to heat the fixing device by comparing the reference temperature TT with the temperature detected by the temperature detection member. The control unit sets the reference temperature TT to the first temperature T1 during continuous printing for a predetermined time or longer, and when receiving a print command, sets the reference temperature TT to the first temperature T1. Second temperature control for setting a higher second temperature T2, and after executing the second temperature control, before the recording sheet is supplied to the fixing device, the reference temperature TT is set to a third temperature T3 higher than the second temperature T2. and a third temperature control to be set. [Selection drawing] Fig. 8

Description

  The present invention relates to an image forming apparatus including a fixing device having a heater, a program applied to a computer that controls the image forming apparatus, and a control method for the image forming apparatus.

  Conventionally, in an image forming apparatus equipped with a fixing device, in order to improve the fixability from the first sheet, when starting up the fixing device, the target temperature is set higher than the fixing temperature at the time of fixing, and the heater is controlled. One having a control means for heating the fixing device is known (for example, see Patent Document 1).

JP 2002-108133 A

  However, in the above-described technique, when the temperature of the fixing device reaches the target temperature before the recording sheet is supplied to the fixing device, the output of the heater decreases when the first recording sheet is supplied to the fixing device. There may be. As described above, when the output of the heater is lowered when the recording sheet is supplied to the fixing device, the temperature of the fixing device is lowered, and the fixability may be deteriorated.

  SUMMARY OF THE INVENTION Accordingly, the present invention provides an image forming apparatus, a program, and an image forming apparatus capable of suppressing the output of the heater from greatly decreasing when a recording sheet is supplied to a fixing device and fixing the first recording sheet satisfactorily. It is an object to provide a control method.

In order to achieve the above object, an image forming apparatus of the present invention includes an image forming unit that forms a developer image on a recording sheet, a roller that supplies the recording sheet to the image forming unit, a heater, and a temperature detection member. A fixing unit that heats the recording sheet sent from the image forming unit, and a control unit that controls the heater to heat the fixing unit based on a comparison between a reference temperature and a temperature detected by the temperature detection member. I have.
When the control unit receives the first temperature control for setting the reference temperature to the first temperature and the print command during the continuous printing for a predetermined time or longer, the control unit raises the reference temperature to be higher than the first temperature. The second temperature control for setting the second temperature, and the third temperature control for setting the reference temperature to a third temperature higher than the second temperature immediately after the recording sheet is supplied to the fixing device after executing the second temperature control. And execute.

  According to the image forming apparatus configured as described above, the reference temperature rises to the third temperature before the recording sheet is supplied to the fixing device, so that the output of the heater is reduced when the recording sheet is supplied to the fixing device. Can be suppressed. As a result, the recording sheet is supplied to the fixing device, so that the temperature of the fixing device is not greatly lowered, and the first recording sheet can be satisfactorily fixed.

  The program according to the present invention includes an image forming unit that forms a developer image on a recording sheet, a roller that supplies the recording sheet to the image forming unit, a heater, and a temperature detection member. A program applied to a computer that controls an image forming apparatus including a fixing device that heats a sheet, wherein the computer controls a heater to control the fixing device with a reference temperature and a temperature detected by the temperature detection member. The heating control for heating based on the comparison, the first temperature control for setting the reference temperature to the first temperature during continuous printing for a predetermined time or longer, and the reference temperature when the printing command is received. After executing the second temperature control for setting the second temperature higher than the first temperature and the second temperature control, the reference temperature is set to the third temperature higher than the second temperature before the recording sheet is supplied to the fixing device. Third temperature system And, to the execution.

  According to the program configured as described above, the reference temperature is raised to the third temperature before the recording sheet is supplied to the fixing device, so that the output of the heater is reduced when the recording sheet is supplied to the fixing device. Can be suppressed. As a result, the recording sheet is supplied to the fixing device, so that the temperature of the fixing device is not greatly lowered, and the first recording sheet can be satisfactorily fixed.

  An image forming apparatus control method according to the present invention includes an image forming unit that forms a developer image on a recording sheet, a roller that supplies the recording sheet to the image forming unit, a heater, and a temperature detection member. A control method for an image forming apparatus comprising: a fixing device that heats a sent recording sheet, wherein the fixing device is controlled based on a comparison between a reference temperature and a temperature detected by the temperature detection member by controlling a heater. When the heating control for heating, the first temperature control for setting the reference temperature to the first temperature during the continuous printing for a predetermined time or more, and the printing command are received, the reference temperature is higher than the first temperature. The second temperature control for setting the second temperature and the third temperature control for setting the reference temperature to a third temperature higher than the second temperature before the recording sheet is supplied to the fixing device after the second temperature control is executed. And execute.

  According to such a control method of the image forming apparatus, the reference temperature is raised to the third temperature before the recording sheet is supplied to the fixing device, so that the output of the heater is lowered when the recording sheet is supplied to the fixing device. Can be suppressed. As a result, the recording sheet is supplied to the fixing device, so that the temperature of the fixing device is not greatly lowered, and the first recording sheet can be satisfactorily fixed.

  According to the present invention, it is possible to suppress a decrease in the output of the heater when the recording sheet is supplied to the fixing device. As a result, the recording sheet is supplied to the fixing device, so that the temperature of the fixing device is not greatly lowered, and the first recording sheet can be satisfactorily fixed.

1 is a diagram illustrating a schematic configuration of a laser printer according to an embodiment of the present invention. It is sectional drawing of a fixing device. It is a perspective view of a fixing device. It is a block diagram which shows a 1st thermistor, a control part, a drive source, a heater, and a pick-up roller. It is a flowchart which shows the control action of a control part. It is a flowchart which shows the control action of a control part. It is a flowchart which shows the control action of mode selection control. 10 is a timing chart showing a change in reference temperature and a paper feed timing when the predetermined temperature is the first predetermined temperature in the second supply mode. 10 is a timing chart showing a change in reference temperature and a paper feed timing when the predetermined temperature is the second predetermined temperature in the second supply mode. 6 is a timing chart showing a change in reference temperature and paper feed timing in a first supply mode.

  Next, embodiments of the present invention will be described in detail with reference to the drawings as appropriate. In the following description, first, a schematic configuration of the laser printer 1 as an example of an image forming apparatus according to an embodiment of the present invention will be described, and then a characteristic part of the present invention will be described.

  As shown in FIG. 1, the laser printer 1 includes a main body housing 2 in which a paper sheet 3 as an example of a recording sheet is fed, an exposure device 4, and a toner image (developer image) on the paper P. ) Mainly, a process cartridge 5 as an example of an image forming unit, a fixing device 100 that thermally fixes a toner image transferred onto a sheet P, a drive source 8, and a control unit 10.

  In the following description, the direction will be described with reference to the user who uses the laser printer. That is, the right side in FIG. 1 is “front”, the left side is “rear”, the front side is “left”, and the back side is “right”. Also, the vertical direction in FIG.

  The paper feed unit 3 is provided in the lower part of the main body housing 2, and includes a paper feed tray 31 that accommodates the paper P, a pressure plate 32, a pickup roller 33 as an example of a roller, a paper feed pad 34, and paper dust Deposition rollers 35 and 36 and a registration roller 37 are mainly provided.

  The pickup roller 33 is disposed above the front end portion of the paper feed tray 31. The pickup roller 33 is configured to supply the paper P to the process cartridge 5 by rotating while contacting the paper P stored in the paper feed tray 31.

  The pressure plate 32 is provided in the paper feed tray 31 and supports the paper P stored in the paper feed tray 31. The pressure plate 32 is configured so that the front end portion of the paper P stored in the paper feed tray 31 approaches the pickup roller 33. The pressure plate 32 rotates around the rear end portion, so that it is positioned at the lowest position and separated from the pickup roller 33 (see the broken line), and is rotated upward from the separation position to be more than the separation position. The paper P can be moved to a paper feed position (see a solid line) close to the pickup roller 33 and in contact with the pickup roller 33. Note that the paper feed position differs depending on the number of sheets P stored in the paper feed tray 31. The laser printer 1 includes a known sensor, and can detect whether the pressure plate 32 is located at the separation position or the paper feeding position.

  In the paper feed unit 3, the paper P in the paper feed tray 31 is brought close to the pickup roller 33 by the pressure plate 32 and separated one by one by the pickup roller 33 and the paper feed pad 34, and the paper dust removing rollers 35 and 36 and the resist The toner is conveyed toward the process cartridge 5 through the adjustment roller 37.

  The exposure apparatus 4 is arranged at the upper part in the main body housing 2 and mainly includes a laser light emitting unit (not shown), a polygon mirror 41 that is rotationally driven, lenses 42 and 43, and reflecting mirrors 44, 45, and 46. In preparation. In the exposure apparatus 4, the laser light (see the chain line) based on the image data emitted from the laser light emitting part is reflected or passed through the polygon mirror 41, the lens 42, the reflecting mirrors 44 and 45, the lens 43 and the reflecting mirror 46 in this order. The surface of the photosensitive drum 61 is scanned at high speed.

  The process cartridge 5 is disposed below the exposure apparatus 4 and is detachably mounted on the main body housing 2 through an opening formed when the front cover 21 provided on the main body housing 2 is opened. Yes. The process cartridge 5 includes a drum unit 6 and a developing unit 7.

  The drum unit 6 mainly includes a photosensitive drum 61, a charger 62, and a transfer roller 63. The developing unit 7 is configured to be detachably attached to the drum unit 6, and includes a developing roller 71, a supply roller 72, a layer thickness regulating blade 73, and a toner that contains toner (developer). The container mainly includes a container 74 and an agitator 75 that stirs the toner in the toner container 74 and supplies the toner to the supply roller 72.

  In the process cartridge 5, the surface of the photosensitive drum 61 is uniformly charged by the charger 62 and then exposed by high-speed scanning of the laser light from the exposure device 4, whereby image data is transferred onto the photosensitive drum 61. An electrostatic latent image based on is formed. Further, the toner in the toner container 74 is supplied to the developing roller 71 via the supply roller 72 and enters between the developing roller 71 and the layer thickness regulating blade 73 to form a thin layer of a certain thickness on the developing roller 71. It is carried on.

  The toner carried on the developing roller 71 is supplied from the developing roller 71 to the electrostatic latent image formed on the photosensitive drum 61. As a result, the electrostatic latent image is visualized and a toner image is formed on the photosensitive drum 61. Thereafter, the paper P is conveyed between the photosensitive drum 61 and the transfer roller 63, whereby the toner image on the photosensitive drum 61 is transferred onto the paper P.

  The fixing device 100 is provided behind the process cartridge 5. The fixing device 100 is configured to thermally fix the toner image transferred on the paper P onto the paper P by conveying and heating the paper P sent from the process cartridge 5. The paper P on which the toner image has been thermally fixed by the fixing device 100 is discharged onto the paper discharge tray 22 by the transport rollers 23 and 24.

  2 and 3, the fixing device 100 includes a fixing belt 110, a heater 120, a nip plate 130, a reflection plate 140, a pressure roller 150, a stay 160, and a temperature detection member. The first thermistor 171, the second thermistor 172, and the thermostat 180 are mainly provided.

  The fixing belt 110 is an endless (cylindrical) member having heat resistance and flexibility, and rotation is guided by guide members (not shown) at both ends in the width direction.

  The heater 120 is, for example, a halogen lamp, and is provided so as to heat the toner on the paper P by heating the fixing belt 110 (nip portion N) via the nip plate 130. The heater 120 is disposed inside the fixing belt 110 at a predetermined interval from the inner surfaces of the fixing belt 110 and the nip plate 130.

  The nip plate 130 is a plate-like member that receives the pressing force of the pressure roller 150 and transmits radiant heat from the heater 120 to the toner on the paper P via the fixing belt 110, and the lower surface of the nip plate 130 has a cylindrical fixing. It arrange | positions so that the inner surface of the belt 110 may be slidably contacted.

  The nip plate 130 is formed of, for example, an aluminum plate having a thermal conductivity higher than that of a steel stay 160 described later, and mainly includes a substantially flat base portion 131 and a protruding portion 132. Yes.

  The protruding portion 132 is formed so as to protrude rearward along the conveying direction from the rear end portion 131 </ b> R in the conveying direction of the base portion 131. As shown in FIG. 3, two protrusions 132 are formed, one at each of the vicinity of the right end and the center of the rear end portion 131 </ b> R of the base portion 131.

  As shown in FIG. 2, the reflection plate 140 is a member that reflects the radiant heat from the heater 120 toward the nip plate 130 (the inner surface of the base portion 131), and surrounds the heater 120 inside the fixing belt 110. The heater 120 is arranged at a predetermined interval.

  The reflection plate 140 is formed by curving an aluminum plate or the like in a substantially U shape in cross section, for example, having a high infrared and far infrared reflectance. More specifically, the reflecting plate 140 mainly has a reflecting portion 141 having a curved shape (substantially U shape in cross section) and a flange portion 142 extending from both ends of the reflecting portion 141 along the transport direction.

  The pressure roller 150 is a member that forms a nip portion N with the fixing belt 110 by sandwiching the fixing belt 110 with the nip plate 130, and is disposed below the nip plate 130. In the present embodiment, in order to form the nip portion N, the nip plate 130 is urged toward the pressure roller 150. The pressure roller 150 rotates with the fixing belt 110 sandwiched between the nip plate 130 and rotates together with the fixing belt 110 to convey the paper P backward. In order to form the nip portion N, the pressure roller 150 may be biased toward the nip plate 130.

  The pressure roller 150 is driven to rotate, so that the fixing belt 110 is driven to rotate by a frictional force with the fixing belt 110 (or the paper P). The sheet P on which the toner image is transferred is conveyed between the pressure roller 150 and the heated fixing belt 110 (nip portion N), whereby the toner image (toner) is thermally fixed.

  The stay 160 is a member that secures the rigidity of the nip plate 130 by supporting both front and rear ends of the base portion 131 of the nip plate 130, and has a substantially U shape in cross section along the outer surface shape of the reflection portion 141 of the reflection plate 140. And is arranged so as to cover the reflector plate 140. Such a stay 160 has relatively high rigidity, for example, is formed by bending a steel plate or the like into a substantially U shape in cross-sectional view. The stay 160 sandwiches the flange portion 142 of the reflecting plate 140 with the nip plate 130.

  As shown in FIG. 3, the stay 160 has two notches 161 for arranging the first thermistor 171 and the second thermistor 172 on the rear wall 160R. More specifically, the notch 161 is formed so as to have a gap that does not contact the first thermistor 171 and the second thermistor 172 at positions corresponding to the two protrusions 132 of the nip plate 130.

  The first thermistor 171 and the second thermistor 172 are temperature sensors, and are arranged so as to detect the temperature of the fixing device 100, in this embodiment, the temperature of the nip plate 130. The first thermistor 171 is disposed near the center of the nip plate 130 in the left-right direction, and is provided so as to detect the temperature within the range in which the paper P of the nip plate 130 is conveyed. The second thermistor 172 is disposed at the right end of the nip plate 130 and is provided so as to detect a temperature outside the range in which a small-sized sheet P (for example, a postcard or A6 sheet) is conveyed.

  2 and 3, the thermistors 171 and 172 are fixed to the rear wall 160R of the stay 160 by screws 179 inside the fixing belt 110, and the upper surface (fixing) of the protruding portion 132 of the nip plate 130 is fixed. The surface opposite to the surface in sliding contact with the belt 110) is disposed facing the belt 110. In each thermistor 171, 172, the temperature detection surface 171A is in contact with the upper surface of the protrusion 132.

  Further, the thermistors 171 and 172 are arranged outside the reflector 140 in the transport direction. More specifically, the thermistors 171 and 172 are arranged on the downstream side (rear side) of the reflecting plate 140 in the transport direction outside the nip portion N in the transport direction. Further, each thermistor 171, 172 is arranged with a gap between the thermistor 171 and 172 so as not to contact the outer surface of the reflector 140.

  The thermostat 180 is a temperature detection element using bimetal or the like, and is arranged so as to detect the temperature of the reflection plate 140. Specifically, the thermostat 180 is fixed to the stay 160 inside the fixing belt 110 (see FIG. 3), and is disposed in a state where the temperature detection surface 181 faces the reflection plate 140 above the reflection plate 140.

  The thermostat 180 is provided on a circuit that supplies power to the heater 120, and cuts off the power supply to the heater 120 when a temperature equal to or higher than a predetermined value is detected. Thereby, it is possible to prevent the temperature of the fixing device 100 from rising excessively.

  As shown in FIG. 1, the drive source 8 is provided to drive the pressure roller 150 of the fixing device 100 in the present embodiment.

As shown in FIG. 4, the control unit 10 includes a CPU, a ROM, a RAM, and the like, and controls the drive source 8 and the heater 120 based on a program prepared in advance and information acquired by the first thermistor 171. , together with the fuser 100 reference temperature T _T and the first thermistor 171 is heated based on a comparison of the detected temperature, and controls the pickup roller 33, a predetermined timing when the fixing device 100 is a suitable temperature Then, the recording sheet supply is started.

When receiving the print command, the control unit 10 controls the output of the heater 120 by setting the heater control instruction value, and executes the heating control for heating the fixing device 100 toward the reference temperature T _T. Has been. The heater control instruction value is, for example, a duty ratio that represents an energization ratio per time. The output of the heater 120 increases as the heater control instruction value increases. Specifically, the control unit 10 increases the amount of power supplied to the heater 120 as the amount by which the detected temperature of the first thermistor 171 falls below the reference temperature T _T is larger.

When the controller 10 receives the first temperature control for setting the reference temperature T _T to the first temperature T ₁ and the print command during continuous printing for a predetermined time or longer, and receives the print command, the control temperature T It is configured to perform a second temperature control to set _T to the second temperature T ₂ higher than the first temperature T _1. The control unit 10, when a predetermined condition is satisfied, after executing the second temperature control, specifically, the temperature detected by the first thermistor 171, second temperature T ₂ less higher than the first temperature T ₁ of After the fourth temperature TH4 is exceeded, before the paper P is supplied to the fixing device 100, the third temperature control is performed to set the reference temperature T _T to the third temperature T ₃ higher than the second temperature T _2. It is configured as follows. In the present embodiment, the control unit 10 executes the second temperature control and the third temperature control before the pickup roller 33 starts to supply the first sheet P. Further, the fourth temperature TH4 and the predetermined temperature TH3 are set so that the third temperature control is executed immediately before the pickup roller 33 starts supplying the first sheet P, for example, about one second before.

In addition, after the first sheet P is supplied to the fixing device 100, the control unit 10 sets the reference temperature T _T to the first temperature at a temperature interval smaller than the difference between the second temperature T ₂ and the third temperature T _3. is configured to perform a fourth temperature control going stepped down towards T _1. Specifically, the control unit 10, after the first sheet P is fed to the fixing device 100, pulling the constant C1 from the reference temperature T _T in a predetermined time interval until the first temperature T _1, the new reference setting the temperature _{T T.}

Control unit 10, a predetermined timing after the start of heating the fixing device 100, in this embodiment, the second predetermined time B2 elapses after the heater 120 to ON, the detection temperature _{T B2} of the first thermistor 171 is first If it is equal to or greater than the threshold TH1, the first supply mode is selected, and the first supply control for supplying the first sheet P at the first timing by the pickup roller 33 is executed (first supply control execution process). Then, the control unit 10, the second predetermined time B2 elapses after the heater 120 to ON, when the detected temperature _{T B2} of the first thermistor 171 is less than the first threshold value TH1, select the second supply mode Then, the second supply control for supplying the first sheet P by the pickup roller 33 at the second timing later than the first timing is executed (second supply control execution processing). The timing of the control unit 10 compares the detected temperature T _B2 of the first thermistor 171 of the first threshold value TH1 may be effected even if that has passed since receiving a printing command given time, by driving the drive source 8 It may be when a predetermined time has passed.

Specifically, the first timing is when the standby time t0 has elapsed since the heater 120 was turned on. That is, in the first supply control, the control unit 10 rotates the pickup roller 33 to supply the first sheet P when the standby time t0 has elapsed after the heating of the fixing device 100 is started. The first timing may be when the standby time t0 has elapsed after receiving the print command, or when the standby time t0 has elapsed since the drive source 8 was driven. The second timing is when the temperature T detected by the first thermistor 171 reaches the predetermined temperature TH3 after the heater 120 is turned on. That is, in the second supply control, the controller 10 rotates the pickup roller 33 to rotate the first sheet when the temperature T detected by the first thermistor 171 reaches the predetermined temperature TH3 after the heating of the fixing device 100 is started. Paper P is supplied. The waiting time t0 is set to the shortest time that the fixing device 100 reaches an appropriate temperature before the supplied first sheet P reaches the fixing device 100. The predetermined temperature TH3, for example, a second temperature T ₂ above temperature, until the first sheet P fed reaches the fixing unit 100, fixing unit 100 is appropriate temperature The lowest temperature is set.

The control unit 10, when selecting the second supply mode, the second after a predetermined time B2 from the heater 120 to ON, low detection temperature _{T B2} of the first thermistor 171 than the first threshold value TH1 first lower than second threshold TH2, the detected temperature _{T B2} of the first thermistor 171 than in the case of more than the second threshold TH2, set to a low value the predetermined temperature TH3. Specifically, the control unit 10, the second after a predetermined time B2 from the heater 120 to ON, when the detected temperature _{T B2} of the first thermistor 171 is the second threshold TH2 or more, the first predetermined predetermined temperature TH3 set to a temperature A1, the detected temperature _{T B2} of the first thermistor 171 is less than the second threshold TH2, setting a predetermined temperature TH3 lower than the first predetermined temperature A1 second predetermined temperature A2.

  The control unit 10 controls rotation / stop of the pickup roller 33 by controlling a motor that drives the pickup roller 33 provided separately from the drive source 8. The control of rotation / stop of the pickup roller 33 by the control unit 10 is not limited to this. For example, a solenoid actuator that drives the pickup roller 33 up and down may be controlled. The laser printer 1 also includes a drive transmission mechanism that can be switched between a connected state in which the driving force of the driving source 8 can be transmitted to the pickup roller 33 and a disconnected state in which the driving force of the driving source 8 is cut off. May control rotation / stop of the pickup roller 33 by controlling the drive transmission mechanism.

  Then, when the second supply mode is selected and the predetermined temperature TH3 is set to the first predetermined temperature A1, the control unit 10 performs the third temperature control and executes the first sheet. P is supplied. In addition, the control unit 10 determines that the first supply mode is selected, the second supply mode is selected, and the predetermined temperature TH3 is set to the second predetermined temperature A2. The first sheet P is supplied without executing the three-temperature control.

Next, a specific control operation of the control unit 10 will be described.
5, the control unit 10 receives the print command (S1), sets the reference temperature _{T T} in the second temperature _{T 2} (S2). And the control part 10 performs a mode selection process (S3).

7, the control unit 10 starts the mode selection process, the detected temperature _{T B2} of the first thermistor 171 from the start of heating after the second predetermined time B2 of the fuser 100, the first threshold value TH1 or more It is determined whether or not there is (S31).

In step S31, the detected temperature _{T B2} of the first thermistor 171 from the start of heating after the second predetermined time B2 of the fuser 100, it is determined to be the first threshold value TH1 or more (S31, Yes), the first supply mode Select (S32) and end the mode selection process.

In step S31, the detected temperature _{T B2} of the first thermistor 171 from the start of heating after the second predetermined time B2 of the fuser 100, if judging that it is the first threshold value TH1 or more (S31, No), the control unit 10, the after selecting the second supply mode (S33), the detected temperature _{T B2} of the fixing unit 100 a first thermistor 171 from the start of heating after the second predetermined time B2 of, it is determined whether the second threshold value TH2 or more ( S34).

In step S34, the detected temperature _{T B2} of the first thermistor 171 from the start of heating after the second predetermined time B2 of the fuser 100, it is determined to be the second threshold value TH2 or more (S34, Yes), the control unit 10, The predetermined temperature TH3 is set to the first predetermined temperature A1 (S35). On the other hand, in step S34, the detected temperature _{T B2} of the first thermistor 171 from the start of heating after the second predetermined time B2 of the fuser 100, if judging that it is the second threshold value TH2 or more (S34, No), the control unit 10 The predetermined temperature TH3 is set to the second predetermined temperature A2 (S36).

  When the value of the predetermined temperature TH3 is set in step S35 or step S36, the control unit 10 ends the mode selection process.

  As shown in FIG. 5, after the mode selection process, the control unit 10 determines whether or not the first supply mode is selected (S4).

  If it is determined in step S4 that the first supply mode is selected (S4, Yes), the control unit 10 determines whether or not the standby time t0 has elapsed from the start of heating of the fixing device 100 (S5). If it is determined in step S5 that the standby time t0 has not elapsed (S5, No), the control unit 10 waits until the standby time t0 has elapsed. If it is determined in step S5 that the standby time t0 has elapsed (S5, Yes), the control unit 10 rotates the pickup roller 33 to pick up the first sheet P (S6).

  If it is determined in step S4 that the first supply mode is not selected (S4, No), the controller 10 determines whether or not the predetermined temperature TH3 is the first predetermined temperature A1 (S7).

  If it is determined in step S7 that the predetermined temperature TH3 is not the first predetermined temperature A1 (S7, No), the control unit 10 determines whether or not the temperature T detected by the first thermistor 171 is equal to or higher than the predetermined temperature TH3. (S8). If it is determined in step S8 that the temperature T detected by the first thermistor 171 is not equal to or higher than the predetermined temperature TH3 (S8, No), the control unit 10 until the temperature T detected by the first thermistor 171 becomes equal to or higher than the predetermined temperature TH3. stand by. In step S8, when it is determined that the temperature T detected by the first thermistor 171 is equal to or higher than the predetermined temperature TH3 (S8, Yes), the control unit 10 rotates the pickup roller 33 to rotate the first sheet P. Is picked up (S6).

If it is determined in step S7 that the predetermined temperature TH3 is the first predetermined temperature A1 (S7, Yes), the control unit 10 determines whether or not the temperature T detected by the first thermistor 171 is equal to or higher than the fourth temperature TH4. Determine (S9). If it is determined in step S9 that the temperature T detected by the first thermistor 171 is not equal to or higher than the fourth temperature TH4 (S9, No), the control unit 10 determines that the temperature T detected by the first thermistor 171 is equal to or higher than the fourth temperature TH4. Wait until Then, in step S9, when the temperature T of the first thermistor 171 has detected is determined to be the fourth temperature TH4 or more (S9, Yes), the control unit 10 sets the reference temperature _{T T} in the third temperature _{T 3} (S10).

  After step S10, the control unit 10 proceeds to step S8, and when the temperature T detected by the first thermistor 171 becomes equal to or higher than the predetermined temperature TH3 (S8, Yes), the pickup roller 33 is rotated to rotate the first sheet. Sheet P is picked up (S6).

As shown in FIG. 6, after step S6, the control unit 10 is to draw constant C1 from the current reference temperature _{T T,} it sets a new reference temperature _{T T} (S11). Then, the control unit 10 compares the reference temperature T _T set in step S11 with the first temperature T ₁ and sets the larger temperature as the reference temperature T _T (S12).

Setting the reference temperature _{T T} in step S12, the control unit 10 determines whether to end the printing (S13). In step S13, it is determined not to end the printing (S13, No), the control unit 10 returns to step S11, again sets the reference temperature _{T T.} And if it determines with complete | finishing printing in step S13 (S13, Yes), the control part 10 will complete | finish control.

  Next, the operation of the laser printer 1 will be described. In the following description, a case where a print command is input while the fixing device 100 is cooled to about room temperature will be described.

  First, the case where the third temperature control is executed, that is, the case where the second supply mode is selected and the predetermined temperature TH3 is set to the first predetermined temperature A1 will be described with reference to FIG.

Upon receiving the print command, the control unit 10 sets the reference temperature T _T to the second temperature T ₂ and turns on the heater 120 (time t1). Accordingly, the temperature of the fixing device 100 begins to rise toward the second temperature T _2.

  After the heater 120 is turned on, the drive source 8 is turned on (time t2). As a result, the pressure roller 150 of the fixing device 100 starts to rotate.

The second predetermined time after B2 from when the heater 120 is in ON (time t3), the detected temperature _{T B2} of the first thermistor 171, if it is first less than the threshold value TH1 and second threshold value TH2 or more, the control unit 10, The predetermined temperature TH3 is set to the first predetermined temperature A1.

Then, the temperature T of the first thermistor 171 has detected reaches the fourth temperature TH4 (time t4), the control unit 10 sets the reference temperature _{T T} in the third temperature _{T 3.} At this time, the control unit 10 sets the heater control instruction value to a large value.

When the temperature T detected by the first thermistor 171 reaches the first predetermined temperature A1 (time t5), the pickup roller 33 rotates and the first sheet P is supplied. Then, the reference temperature T _T of the control unit 10 sets the continue to decrease by a constant C1 at regular intervals, Continuing printing continuously, the first temperature T ₁ of a predetermined time after.

Thus, since the reference temperature T _T immediately before the first sheet P is fed by the pickup roller 33 is increased, the control unit 10 is maintained at a large value of the heater control instruction value. Therefore, the first sheet P reaches the fixing device 100 with the output of the heater 120 being high. Thereby, when the first sheet P reaches the fixing device 100, it is possible to suppress the temperature of the fixing device 100 from rapidly decreasing, so that the fixing quality is maintained from the first sheet P. be able to.

  Next, the case where the second supply mode is selected and the predetermined temperature TH3 is set to the second predetermined temperature A2 among the cases where the third temperature control is not performed will be described with reference to FIG.

Upon receiving the print command, the control unit 10 sets the reference temperature T _T to the second temperature T ₂ and turns on the heater 120 (time t1). Then, after the heater 120 is turned on, the drive source 8 is turned on (time t2). As a result, the pressure roller 150 of the fixing device 100 starts to rotate.

The second predetermined time after B2 from when the heater 120 is in ON (time t3), the detected temperature _{T B2} of the first thermistor 171, if it is and less than the second threshold TH2 lower than the first threshold value TH1, the control unit 10, The predetermined temperature TH3 is set to the second predetermined temperature A2.

When the temperature T detected by the first thermistor 171 reaches the second predetermined temperature A2 (time t7), the pickup paper 33 rotates to supply the first sheet P. Then, the reference temperature T _T of the control unit 10 sets the continue to decrease by C1 every predetermined time, Continuing printing continuously, the first temperature T ₁ of a predetermined time after.

From becoming heater 120 is turned ON detection temperature _{T B2} of the first thermistor 171 after the second predetermined time B2 is less than the first threshold value TH1 and second threshold TH2, the temperature T for detecting the first thermistor 171 is quite It does not reach the reference temperature T _T, control unit 10 is maintained to a large value of the heater control instruction value. Therefore, the output of the heater 120 is unlikely to decrease before the first sheet P reaches the fixing device 100. Also, if the temperature T of the first thermistor 171 detects low, actively fuser 100 (the pressure roller 150, such as the nip plate 130) for setting a high reference temperature T _T in order to heat storage, the first thermistor The temperature T detected by 171 is difficult to reach due to the reference temperature T _T. Therefore, when after becoming the heater 120 is turned ON detection temperature _{T B2} of the first thermistor 171 after the second predetermined time B2 is less than the first threshold value TH1 and second threshold value TH2, 1 sheet of paper P is fixed When the toner is supplied to the fixing device 100, the temperature of the fixing device 100 does not decrease as the fixing property deteriorates.

  Next, a case where the first supply mode is selected among the cases where the third temperature control is not performed will be described with reference to FIG.

Upon receiving the print command, the control unit 10 sets the reference temperature T _T to the second temperature T ₂ and turns on the heater 120 (time t1). Then, after the heater 120 is turned on, the drive source 8 is turned on (time t2). As a result, the pressure roller 150 of the fixing device 100 starts to rotate.

When the heater 120 is a second predetermined time after the B2 after becoming ON (time t3), the detected temperature _{T B2} of the first thermistor 171, is the first threshold value TH1 or more, time waits heater 120 is turned ON t0 Has elapsed (time t8), the pickup roller 33 rotates and the first sheet P is supplied. Then, the reference temperature T _T of the control unit 10 sets the continue to decrease by C1 every predetermined time, Continuing printing continuously, the first temperature T ₁ of a predetermined time after.

Thus, if the detected temperature _{T B2} of the first thermistor 171 from the heater 120 is turned ON after the second predetermined time B2 is the first threshold value TH1 or more, because of the power supply voltage is high or the like, the heater 120 The actual output is high and the fixing device 100 is easily heated. Therefore, even when the third temperature control is not performed, when the first sheet P is supplied to the fixing device 100, even if the heater control instruction value is not set to a large value, the fixing performance becomes worse. The temperature of the vessel 100 does not decrease.

  As described above, in the present embodiment, the third temperature control is executed only when the second supply mode is selected and the predetermined temperature TH3 is set to the first predetermined temperature A1, so that it is necessary. Only the third temperature control can be executed.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment. About a concrete structure, it can change suitably in the range which does not deviate from the meaning of this invention.

In the above embodiment, in the third temperature control, the reference temperature T _T is raised to the third temperature T ₃ when the fourth temperature TH4 is exceeded, but the timing for raising the reference temperature T _T to the third temperature T ₃ is this. It is not limited to. For example, the control unit 10 is configured to supply the first sheet P by rotating the pickup roller 33 after a third predetermined time after the temperature T detected by the first thermistor 171 reaches the predetermined temperature TH3. When the temperature T detected by the first thermistor 171 reaches the predetermined temperature TH3, or after the temperature T detected by the first thermistor 171 reaches the predetermined temperature TH3, before the third predetermined time elapses, The reference temperature T _T may be configured to increase from the second temperature T ₂ to the third temperature T ₃ .

In addition, after the first sheet P is supplied by the pickup roller 33, the control unit 10 changes the reference temperature T _T from the second temperature T ₂ to the third temperature T T before the sheet P reaches the fixing device 100. _It may be configured to increase to ₃ .

In the above embodiment, the control unit 10, when after receiving the print instruction to ON heater 120, the reference temperature T _T were set to the second temperature T _2, the setting of the reference temperature limitation Is not to be done. For example, when receiving the print command, the control unit 10 sets the reference temperature T _T to the fifth temperature T ₅ lower than the second temperature T ₂ , and after the fourth predetermined time after the heater 120 is turned on, the reference temperature T _T is set. it may be configured to set _T to the second temperature T _2.

  In the embodiment, the control unit 10 is configured not to execute the third temperature control when the first mode is selected, but the control operation of the control unit is not limited to this. Even when the first supply mode is selected, the output of the heater 120 may decrease immediately before the first sheet P reaches the fixing device 100. When the temperature reaches the fixing device 100, the temperature of the fixing device 100 may drop rapidly. Therefore, the control unit may execute the third temperature control depending on conditions even when the first supply mode is selected.

  In the above embodiment, the pickup roller 33 is exemplified as the roller. However, the roller is not limited to this, and may be a registration roller 37, for example.

  In the embodiment, the fixing device 100 including the fixing belt 110 and the nip plate 130 is illustrated, but the configuration of the fixing device is not limited thereto. For example, the fixing device may include a heating roller heated by a heater and a pressure roller that conveys the paper P while sandwiching the paper P between the heating rollers. In this case, the temperature detection member may be provided so as to detect the temperature of the heating roller.

  In the embodiment, the control operation by the control unit 10 is executed by the CPU. However, the configuration of the control unit is not limited to this, and part of the configuration is an FPGA (Field Programmable Gate Array), an ASIC (Application Specific Integrated Circuit), It may be executed by a logic circuit (digital circuit) such as a PGA (Programmable Gain Amplifier).

DESCRIPTION OF SYMBOLS 1 Laser printer 10 Control part 33 Pickup roller 100 Fixing device 120 Heater 171 1st thermistor P Paper T ₁ 1st temperature T ₂ 2nd temperature T ₃ 3rd temperature TH1 1st threshold value TH2 2nd threshold value T _T reference temperature

Claims (10)

An image forming unit for forming a developer image on a recording sheet;
A roller for supplying a recording sheet to the image forming unit;
A fixing device that has a heater and a temperature detection member, and that heats the recording sheet sent from the image forming unit;
A controller that controls the heater to heat the fixing device based on a comparison between a reference temperature and a temperature detected by the temperature detection member;
When the control unit receives the first temperature control for setting the reference temperature to the first temperature and the print command during continuous printing for a predetermined time or more, and the print command, the control unit sets the reference temperature to the first temperature. After executing the second temperature control for setting a higher second temperature and the second temperature control, before the recording sheet is supplied to the fixing device, the reference temperature is set to a third temperature higher than the second temperature. And a third temperature control to be set.   The image forming apparatus according to claim 1, wherein the controller executes the second temperature control before the roller starts to supply the first recording sheet.   The image forming apparatus according to claim 2, wherein the control unit executes the third temperature control before the roller starts to supply the first recording sheet.   The image forming apparatus according to claim 3, wherein the control unit executes the third temperature control after a temperature detected by the temperature detection member exceeds a fourth temperature that is equal to or lower than the second temperature. .   The image forming apparatus according to claim 4, wherein the fourth temperature is higher than the first temperature.   The control unit executes the third temperature control when the detected temperature of the temperature detecting member is less than a first threshold, and when the detected temperature of the temperature detecting member is equal to or higher than the first threshold, 6. The image forming apparatus according to claim 1, wherein the first recording sheet is supplied without executing the third temperature control.   The control unit executes the third temperature control when the detected temperature of the temperature detecting member is equal to or higher than a second threshold lower than the first threshold, and the detected temperature of the temperature detecting member is the second threshold. 7. The image forming apparatus according to claim 6, wherein the first recording sheet is supplied without executing the third temperature control when the temperature is less than the upper limit.   After the first recording sheet is supplied to the fixing device, the control unit gradually changes the reference temperature toward the first temperature at a temperature interval smaller than the difference between the second temperature and the third temperature. The image forming apparatus according to claim 1, wherein a fourth temperature control is performed to decrease the temperature to 4 degrees. An image forming unit that forms a developer image on the recording sheet, a roller that supplies the recording sheet to the image forming unit, a heater and a temperature detection member, and heating the recording sheet sent from the image forming unit A program applied to a computer that controls an image forming apparatus including a fixing device,
Heating control for controlling the heater to heat the fixing device based on a comparison between a reference temperature and a temperature detected by the temperature detection member;
A first temperature control for setting the reference temperature to a first temperature during continuous printing for a predetermined time or more;
A second temperature control for setting the reference temperature to a second temperature higher than the first temperature when receiving a print command;
A third temperature control for setting the reference temperature to a third temperature higher than the second temperature before the recording sheet is supplied to the fixing device after executing the second temperature control;
A program characterized by having executed. An image forming unit that forms a developer image on the recording sheet, a roller that supplies the recording sheet to the image forming unit, a heater and a temperature detection member, and heating the recording sheet sent from the image forming unit A control method of an image forming apparatus comprising: a fixing device;
Heating control for controlling the heater to heat the fixing device based on a comparison between a reference temperature and a temperature detected by the temperature detection member;
A first temperature control for setting the reference temperature to a first temperature during continuous printing for a predetermined time or more;
A second temperature control for setting the reference temperature to a second temperature higher than the first temperature when receiving a print command;
And a third temperature control for setting the reference temperature to a third temperature higher than the second temperature before the recording sheet is supplied to the fixing device after the second temperature control is performed. And a control method of the image forming apparatus.

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