JP2010102210A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus, of which the time for warming up is shortened by shortening the time, until the surface temperature value of a fixing roller reaches the desired temperature value. <P>SOLUTION: The image forming apparatus heating and fixing an image recording medium to which a developer image is transferred includes: a heat source; a fixing part heated by the heat source; a pressure part arranged to face the fixing part and pressing the fixing part; a temperature detecting part, arranged in the medium passage area of the fixing part and detecting the temperature value of the fixing part; and a rotation control part for controlling the rotation of the fixing part with the pressure part. The rotation control part stops the rotation of the fixing part and that of the pressure part, when the temperature of the fixing part detected by the temperature detecting part reaches the temperature value which is lower than the preset standby temperature by a preset temperature value. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus having thermal fixing in an image forming process such as a printer, a facsimile machine, and a copying machine.

  In a conventional image forming apparatus such as a printer, a facsimile machine, and a copying machine, for example, a printer, the surface of a photosensitive drum as an image carrier is uniformly charged with a charging member such as a charging roller, and then an image is obtained. By irradiating light based on data using an exposure device such as an LED (Light Emitting Diode) head, an electrostatic latent image is formed on the surface.

  Then, toner as a developer is electrostatically attached to the electrostatic latent image formed on the surface of the photosensitive drum by a developer supply member such as a developing roller, whereby the toner image is reversely developed. The toner image formed on the surface of the photosensitive drum is transferred onto a recording medium conveyed at a predetermined timing by a transfer member such as a transfer roller. Thereafter, the recording medium onto which the toner image has been transferred is conveyed to a fixing unit, and the toner image is fixed on the recording medium by applying heat and pressure. The recording medium on which the toner image is fixed is discharged outside the printer, and a series of image formation is completed.

  In a printer having such a configuration, the fixing unit generally has a fixing roller as a heat applying body provided with a heating body, and a pressure roller as a pressure applying body arranged to press the fixing roller. And comprising. The fixing roller and the pressure roller are maintained in pressure contact with each other, and heat and pressure are applied in accordance with the timing at which the recording medium passes through the nip formed by the rotating fixing roller and pressure roller. . In the vicinity of the surface of the fixing roller, a temperature detection unit such as a thermistor is provided for detecting the surface temperature value of the fixing roller. The surface temperature of the fixing roller is controlled by turning on / off the heating body based on the temperature value detected by the temperature detection unit.

  Such control of the surface temperature of the fixing roller accompanied by rotation of the fixing roller and turning on / off of the heating body is mainly performed from the time when the printer is turned on, and after warming up, the printer can form an image. That is, the process is executed until the surface temperature value of the fixing roller reaches a desired temperature value (see, for example, Patent Document 1). During image formation, the surface temperature value of the fixing roller is maintained at the optimum temperature most suitable for image formation.

JP 2007-271935 A

  However, the conventional image forming apparatus has a problem that it takes a very long time for the surface temperature of the fixing roller to reach a desired temperature value, and as a result, the time required for warm-up becomes long.

  The present invention has been made in view of such circumstances, and an object of the present invention is to shorten the time required for the surface temperature value of the fixing roller to reach a desired temperature value, thereby increasing the time required for warm-up. It is an object of the present invention to provide an image forming apparatus capable of shortening the above.

  In order to solve the above problems, an image forming apparatus according to the present invention is an image forming apparatus that heat-fixes an image recording medium onto which a developer image has been transferred, and includes a heat source, a fixing unit that is heated by the heat source, A pressure unit that is disposed to face the fixing unit, presses the fixing unit, a temperature detection unit that detects a temperature value of the fixing unit, and a fixing unit; A rotation control unit that controls rotation with the pressurizing unit, and the rotation control unit is a temperature value at which the detected temperature of the fixing unit detected by the temperature detecting unit is lower than a preset standby temperature by a predetermined temperature value The rotation of the fixing unit and the pressurizing unit is stopped when reaching the position.

  An image forming apparatus according to the present invention is an image forming apparatus that heats and fixes an image recording medium onto which a developer image has been transferred, and includes a heat source, an energization control unit that controls energization to the heat source, and an energization control unit. A fixing unit that is heated by a heat source based on the control by the control unit, a temperature detection unit that is disposed in a medium passing area of the fixing unit, detects a temperature value of the fixing unit, and a rotation control unit that controls rotation of the fixing unit; Based on the detection result of the temperature value of the fixing unit by the temperature detecting unit, the energization control unit controls the heat source so as to energize the fixing unit and rotates when the temperature is equal to or higher than the first temperature and lower than the second temperature value. The control unit controls the fixing unit to rotate. When the second temperature value is less than the third temperature value, the energization control unit controls the heat source to energize the fixing unit, and the rotation control unit controls the fixing unit. Control to stop the rotation of , Characterized by.

  According to the image forming apparatus of the present invention, there is provided an image forming apparatus capable of reducing the time required for warm-up by shortening the time until the surface temperature value of the fixing roller reaches a desired temperature value. be able to.

  Embodiments of the present invention will be described below with reference to the drawings. In addition, this invention is not limited to the following description, In the range which does not deviate from the summary of this invention, it can change suitably.

[First Embodiment]
In the description of the first embodiment, the configuration of the printer 1 as an image forming apparatus according to the present invention will be described.

  FIG. 1 is a side cross-sectional view for explaining a main configuration of the printer 1. The printer 1 is an electrophotographic image forming apparatus capable of forming an image based on image data input from an external device such as a host computer on a recording medium.

  The printer 1 includes a medium cassette 3 on which the recording medium 2 is placed, a pickup roller 40 that feeds the recording medium 2 in the direction of the arrow 60, and a pickup roller that transports the recording medium 2 fed by the pickup roller 40 in the direction of the arrow 61. 41, the registration roller 42, the skew of the recording medium 2 is corrected, the conveyance rollers 43 and 44 for conveying the recording medium 2 in the direction of the arrow 62, and the developer images corresponding to the respective colors are formed on the recording medium 2. Photosensitive units (not shown) included in the process units 11, 12, 13, and 14 serving as electrophotographic process units and the transfer belt 20 that electrostatically attracts and conveys the recording medium 2 are provided. The transfer rollers 21, 22, 23, 24 arranged so as to contact the body drum and the recording medium 2 on which the developer image is transferred And a fixing unit 30 for applying pressure, discharge rollers 47 and 48 for discharging the recording medium 2 passing through the fixing unit 30 and conveyed in the direction of arrow 64 to the outside of the printer 1 in the direction of arrow 65, and passing the recording medium 2. Recognizing medium passage sensors 51, 52, 53.

  The medium cassette 3 is housed in a state where the recording medium 2 is stacked inside, and is detachably attached to the lower part of the printer 1. A pickup roller 40 that separates and feeds the recording media 2 one by one is disposed above the medium cassette 3.

  The pickup roller 41 and the registration roller 42 are provided in pressure contact with each other, rotate by the driving force transmitted from a driving source (not shown), and convey the recording medium 2 fed out from the medium cassette 3 to the arrow 61.

  The conveying rollers 43 and 44 are provided in pressure contact with each other, correct the skew of the recording medium 2 and rotate by a driving force transmitted from a driving source (not shown), thereby moving the recording medium 2 in the direction of the arrow 62, that is, in the process. Transport to units 11, 12, 13, and 14.

  The process units 11, 12, 13, and 14 store toners as developers corresponding to four colors of cyan, magenta, yellow, and black, respectively, and display developer images based on input image data, that is, toner images. It is formed on a photosensitive drum (not shown). The process units 11, 12, 13, and 14 are detachably attached from the printer 1 along the transfer belt 20.

  The transfer belt 20 is an endless belt member that electrostatically attracts and transports the recording medium 2. The transfer rollers 21, 22, 23, and 24 are transfer members that transfer the toner images formed on the photosensitive drums of the process units 11, 12, 13, and 14 to the recording medium 2. The transfer rollers 21, 22, 23, and 24 are connected to a transfer roller power source (not shown) that applies a bias voltage having a polarity opposite to that of the toner, and the photosensitive drum is driven by the bias voltage applied from the transfer roller power source. The toner image formed thereon is transferred to the recording medium 2.

  The fixing unit 30 includes a fixing roller 46 as a fixing unit, a pressure roller 45 as a pressing unit, and a first temperature detection element, and a roller temperature detection element 102 as a fixing unit temperature detection element. . For example, the fixing roller 46 covers a heat-resistant elastic layer such as silicone rubber on a hollow cylindrical metal core made of aluminum or the like, and a PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer) tube on the core. It is formed by that. In the cored bar, for example, a heater as a heating element such as a halogen lamp is disposed. The pressure roller 45 has substantially the same configuration as the fixing roller 46 and is arranged to press the fixing roller 46. When the recording medium 2 on which the toner image is transferred passes through the nip formed by the fixing roller 46 and the pressure roller 45, heat and pressure are applied, and the toner image is fixed on the recording medium 2. . The roller temperature detecting element 102 is a temperature detecting element for detecting the surface temperature of the fixing roller 46. For example, a thermistor can be used. Moreover, the pressure part temperature detection element 162 as a 2nd temperature detection element is a temperature detection element for detecting the surface temperature of the pressure roller 45, For example, a thermistor etc. can be used.

  In FIG. 1, the configuration example using the fixing roller 46 and the pressure roller 45 as the members constituting the fixing unit 30 has been described. However, the configuration of the fixing unit 30 is not limited to this. For example, as shown in FIGS. 2 and 3, the fixing unit 30 may be configured by using a fixing roller 101 having a heater 104 and an endless belt 105 incorporating a roller 161 instead of the pressure roller 45. Instead of both the fixing roller and the pressure roller, an endless belt may be used. In this case, the recording medium 2 to which the toner image has been transferred is conveyed in the direction of the arrow in the drawing, and heat and pressure are applied at the timing when it passes through the nip formed by the fixing roller 101 and the endless belt 105. The Further, as shown in FIG. 4, the roller temperature detecting element 102 is disposed between the sheet passing areas in the fixing roller 101 with a minimum sheet width (for example, A6 size_105 mm). Is detected, that is, the surface temperature of the fixing portion.

  The discharge rollers 47 and 48 are provided in pressure contact with each other, and are rotated by a driving force transmitted from a driving source (not shown) to feed the recording medium 2 on which the toner image is fixed in the fixing unit 30 to the printer 1 in the arrow 65 direction. Discharge outside.

  The medium passage sensors 51, 52, and 53 are members that output information as to whether or not the recording medium 2 has passed over the sensor. Even if the sensor can detect the recording medium 2 by mechanical movement, the medium passage sensor 51 A sensor using reflection or transmission may be used.

  Next, the functional configuration of the printer 1 will be described with reference to FIG. The control unit 106 controls the overall operation of the printer 1 and executes a control program stored in a ROM (Read Only Memory) 108 to realize a function of the printer 1; a CPU (Central Processing Unit) 107; The ROM 108, which is a nonvolatile storage medium for storing the control program and setting data, and the working area of the CPU 107, and temporarily storing data such as image data, for example, RAM (Random Access Memory) And the like, a timer 110 for detecting time, an external interface 111 for controlling bidirectional communication of control signals with each control unit built in the printer 1 such as the heater control unit 112, a host computer 151, etc. Host I / F 150 for controlling bidirectional communication of data with externally connected devices, and temperature Or an analog signal output from the environmental sensor 167 for detecting the humidity value and A / D converter 166 into a digital signal.

  The external interface 111 includes a heater control unit 112, a motor drive control unit 113, a fixing unit temperature detection unit 115 serving as a first temperature detection unit, an operation panel control unit 117, and a medium passage sensor 121. And a pressurizing unit temperature detecting unit 165 as a second temperature detecting unit are connected, and the control unit 106 controls the functions of the printer 1 through the external interface 111 in an integrated manner. Realize.

  The heater control unit 112 is connected to the heater 104 via the connection connector 130, and controls on / off of the heater 104 based on the temperature value detected by the fixing unit temperature detection unit 115.

  The motor drive control unit 113 controls the fixing unit rotation mechanism 173 that is a rotation mechanism of the endless belt 105 including the fixing roller 101 and the roller 161 via the drive transmission unit 172.

  The fixing unit temperature detection unit 115 detects the surface temperature value of the fixing roller 101 based on the output of the roller temperature detection element 102 connected via the connection connector 130, and outputs the detected surface temperature value to the control unit 106. To do. The roller temperature detection element 102 may be in contact with the fixing roller 101 or not.

  The operation panel control unit 117 controls, for example, the operation panel 118 including a touch panel and the display unit 119 including an LCD (Liquid Crystal Display), and receives setting input by the user via the operation panel 18. Or the device status of the printer 1 is displayed via the display unit 119.

  The medium passing sensor 121 corresponds to the medium passing sensor 52 described above, and the toner image 123 after passing through the nip formed by the fixing roller 101 and the endless belt 105 is fixed as shown in FIG. Detected recording medium 2

  The pressure unit temperature detection unit 165 detects the surface temperature value of the roller 161 based on the output of the pressure unit temperature detection element 162 connected via the connection connector 130, and the detected surface temperature value is controlled by the control unit 106. Output to.

  Next, processing blocks of the printer 1 will be described in detail with reference to FIG.

  The pressurizing unit temperature detection unit 165 detects the temperature value based on the temperature value information detected by the temperature detection element 162 and outputs the temperature value to the control unit 106 and the temperature comparison unit 116. The temperature comparison unit 116 to which the temperature value is input compares the predetermined temperature value stored in advance in the memory 109 with the temperature value input from the pressurization unit temperature detection unit 165, and the result is sent to the control unit 106. Output. Similarly, the fixing unit temperature detection unit 115 detects a temperature value based on the temperature value information detected by the roller temperature detection element 102, and outputs the temperature value to the control unit 106 and the temperature comparison unit 116. The temperature comparison unit 116 to which the temperature value is input compares the predetermined temperature value stored in advance in the memory 109 with the temperature value input from the fixing unit temperature detection unit 115, and the result is sent to the control unit 106. Output. Based on the comparison result input from the temperature comparison unit 116, the control unit 106 controls the heater control unit 112 and the operation panel control unit 117.

  When a control signal is input from the control unit 106, the heater control unit 112 outputs a control signal for controlling on / off of the heater 104 to the power supply unit 180. The power supply unit 180 supplies power to the heater 104 based on a control signal input from the heater control unit 112. The power supply unit 180 is a power source for the heater 104 and also a power source for the printer 1 main body.

  When a control signal is input from the control unit 106, the operation panel control unit 117 controls the operation panel 118 and the display unit 119. Further, the operation panel control unit 117 outputs each setting information input by the user via the operation panel 118 to the control unit 106.

  The motor drive control unit 113 drives or stops the motor 131 based on the control signal input from the control unit 106. The driving force of the motor 131 is transmitted to the fixing unit rotation mechanism 173 via the drive transmission unit 172.

  Further, the control unit 106 includes a fixing control unit 141, and the fixing control unit 141 outputs a control signal such as the rotation direction and the number of rotations of the motor 131 to the motor drive control unit 113.

  Next, the processing operation of the printer 1 will be described with reference to FIGS. 7, 8, and 9. FIG. 7 is a flowchart for explaining a series of processing operations of the printer 1. FIG. 8 shows an example of a list for determining the temperature difference N. The temperature difference N indicates the temperature rise itself accompanying the rotation stoppage of the fixing roller predicted in advance. Further, FIG. 9A is a diagram for explaining a temperature sequence when the environmental temperature value when the printer 1 is turned on is 20 ° C. or more, and FIG. It is a figure explaining the temperature sequence in the case of less than ° C.

  First, when the printer 1 is turned on in step S101, the control unit 106 executes an initial process of the printer 1 (step S102). The initial processing represents initialization of the control unit 106 including the CPU 107, the memory 109, the timer 110, and the like.

  Next, in step S103, the control unit 106 reads the temperature value information input from the environmental sensor 167, and determines whether or not the temperature value based on the read temperature value information is 20 ° C. or more (step S103). S104).

  Here, when the temperature value is 20 ° C. or higher (step S104 Yes), the control unit 106 refers to the list shown in FIG. 8, sets the value of the temperature difference N to N1 (for example, 20 ° C.), and the N1 Is stored in the memory 109 (step S105). On the other hand, when the temperature value is less than 20 ° C. (No in step S104), the control unit 106 refers to the list shown in FIG. 8, sets the value of the temperature difference N to N2 (for example, 30 ° C.), and sets the N2 to It is stored in the memory 109 (step S106). In the present embodiment, the temperature difference N is determined with 20 ° C. as a boundary, but the present invention is not limited to this. For example, the temperature value information input from the environment sensor 167 may be further divided into 1 ° C increments or 2 ° C increments to determine the temperature difference N, or the temperature difference N may be determined as the temperature input from the environment sensor 167. The temperature difference N may be determined as a function of the value information.

  Next, the control unit 106 determines the fixing roller rotation stop temperature value Te (Te2) from the formula: Te (Te2) = Tg (Tg2) −N (step S107). Tg (Tg2) is a control target temperature value during standby of the printer 1 (hereinafter also simply referred to as standby temperature value), and is a temperature that can be changed by the recording medium 2, the printing speed, and the heat capacity of the fixing roller 101. Value. The temperature difference N is a temperature difference determined in step S105 or step S106 and stored in the memory 109.

  Next, the control unit 106 gives an instruction to the heater control unit 112 to control on / off of the heater 104 based on the determined fixing roller rotation stop temperature value Te (Te2). Upon receiving the instruction, the heater control unit 112 controls the surface temperature of the fixing roller 101 by controlling on / off of the heater 104 via the power supply unit 180 (step S108).

  The control method by the heater control unit 112 sets the standby temperature value Tg (Tg2) as a control target, and the temperature difference information between the standby temperature value Tg (Tg2) and the current surface temperature value of the fixing roller 101 is set at predetermined time intervals. Are sequentially read out, and feedback control for controlling the on-time / off-time of the heater 104 based on the temperature difference information. In this feedback control, the temperature difference component between the standby temperature value Tg (Tg2) and the current surface temperature value of the fixing roller 101 is P, the gradient component between the current temperature difference and the temperature difference one processing step before is D, and the current The cumulative component of the temperature difference in the past for a predetermined time is I, and the value calculated from the constants Kp, Kd, Ki multiplied by the values of P, D, I (Kp * P + Kd * D + Ki * I) This is a control method for determining the ON time and OFF time of the heater 104 from the comparison result with a predetermined threshold value. The constants Kp, Kd, and Ki are values determined from various parameters such as the physical heat capacity of the fixing roller 101, the capacity of the heater 104, and the rotation amount of the fixing roller 101. These values are not always fixed and are controlled. It is a value that can be set as appropriate depending on the application.

  Here, the temperature sequence shown in FIGS. 9A and 9B will be described. 9A and 9B represent times when the main power supply of the printer 1 is turned on. Also, t1 and t1 ′ reach the control (heater on) start time of the heater 104, and t2 and t2 ′ reach the fixing roller rotation start temperature values Tr and Tr2 where the surface temperature value of the fixing roller 101 is the first temperature value. When the rotation of the fixing roller 101 is started, at t3 and t3 ′, the surface temperature value of the fixing roller 101 reaches the fixing roller rotation stop temperature values Te and Te2 which are the second temperature values, and the fixing roller 101 rotates. Are stopped, and t4 and t4 ′ represent times when the surface temperature value of the fixing roller 101 reaches the standby temperature values Tg and Tg2, which are the third temperature values.

  In the sections A and A '(t1-t2, t1'-t2') as the first warm-up control section, the rotation of the fixing roller 101 is stopped and the heater is continuously turned on. Similarly, in the sections B and B ′ (t2-t3, t2′-t3 ′) as the first warm-up control section, the rotation of the fixing roller 101 is started, and the heater is continuously turned on. .

  In the sections C and C ′ (t3−t4, t3′−t4 ′) as the second warm-up control section, the rotation of the fixing roller 101 is stopped and the heater is intermittently turned on. In the sections D and D ′ (after t4, after t4 ′) as standby control sections, the rotation of the fixing roller 101 is stopped and the heater is intermittently turned on. Table 1 summarizes the above time and warm-up control section.

  In the present embodiment, in the “first warm-up control section”, the heater is continuously turned on, and in the “second warm-up control section”, the heater is repeatedly turned on / off intermittently. However, the present invention is not limited to this, and the “first warm-up control section” may be configured such that the heater is intermittently turned on and off repeatedly. However, in this case, it is preferable that the duty ratio at which the heater is turned on is higher than that in the “first warm-up control section”, that is, the ratio at which the heater is turned on is higher than the ratio at which the heater is turned off.

  According to FIGS. 9A and 9B, when the warm-up start timing is around 20 ° C., and the standby temperature value Tg (Tg 2) that is the control target in this embodiment is 170 ° C., step S108 At the start of the control of the heater 104, there is a temperature difference of about 150 ° C. Therefore, the control unit 106 instructs the heater control unit 112 to turn on the heater 104. When the heater 104 is turned on based on the control of the heater control unit 112, the surface temperature value of the fixing roller 101 starts to rise as shown in FIGS. 9A and 9B.

  Next, in step S109, the control unit 106 determines whether or not the surface temperature value of the fixing roller 101 that has started to rise has reached Tr (Tr2) that is the rotation start temperature value of the fixing roller 101. Here, when the surface temperature value of the fixing roller 101 does not reach Tr (Tr2) (No in step S109), the control unit 106 repeats the determination. On the other hand, when the surface temperature value of the fixing roller 101 reaches Tr (Tr2) (Yes in step S109), the fixing control unit 141 instructs the motor drive control unit 113 to start the rotation of the fixing unit rotation mechanism 173. give. Upon receiving the instruction, the motor drive control unit 113 outputs a rotation start signal to the motor 131, and the motor 131 starts rotating. The rotation of the motor 131 is transmitted to the fixing unit rotation mechanism 173 via the drive transmission unit 172, and the fixing roller 101 starts to rotate (step S110).

  Next, the control unit 106 determines whether or not the surface temperature value of the fixing roller 101 has reached Te (Te2) which is the fixing roller rotation stop temperature value (step S111). Here, when the surface temperature value of the fixing roller 101 does not reach Te (Te2) (No in step S111), the control unit 106 repeats the determination. On the other hand, when the surface temperature value of the fixing roller 101 has reached Te (Te2) (Yes in step S111), the fixing control unit 141 instructs the motor drive control unit 113 to stop the fixing unit rotation mechanism 173 from rotating. give. Upon receiving the instruction, the motor drive control unit 113 outputs a rotation stop signal to the motor 131, and the motor 131 stops rotating. By stopping the rotation of the motor 131, the fixing roller 101 stops rotating (step S112).

  Generally, when the rotation of the fixing roller 101 stops, the surface temperature value of the fixing roller 101 overshoots. Here, general overshoot will be described. Overshooting refers to heating of the fixing roller 101 and the roller 161 by the heat energy supplied to the fixing roller 101 and the roller 161 by the heater 104 until the fixing roller 101 is stopped. The energy required to maintain the temperature rise becomes excessive when the fixing roller 101 stops. This excessive energy is released to the outside and appears as an increase in the surface temperature of the fixing roller 101.

  For example, as shown in FIG. 10, when the heater control is started from the point A when the heater control is started, the surface temperature value of the fixing roller increases toward the control target temperature value E. When the surface temperature value of the fixing roller reaches a predetermined temperature value (at the time of roller rotation start B), rotation of the fixing roller is started. Then, when the surface temperature value of the fixing roller reaches the control target temperature (at the time of roller rotation stop C), the rotation of the fixing roller is stopped. As a result, the surface temperature of the fixing roller rapidly increases. When the fixing roller starts rotating, for example, heat is taken away by the pressure roller, and the gradient of the temperature rise is slightly reduced and a constant gradient is continued. As described above, this is because the thermal energy applied by the heater in order to maintain the increase in the surface temperature of the fixing roller becomes excessive due to the rotation of the fixing roller being stopped and released to the outside, and the surface temperature of the fixing roller is rapidly increased. This is to induce a rise.

  The temperature rise due to such overshoot is a rapid temperature rise unlike the temperature rise gradient when the fixing roller is rotating. Generally, “temperature rise gradient due to overshoot”> “fixing roller is The relationship of “temperature rise gradient when rotating” is established.

  In the present invention, the above-described overshoot is used, and further, by controlling the heater on / off immediately after the rotation of the fixing roller stops, the surface temperature value of the fixing roller reaches the standby temperature value Tg. Time can be shortened and the time taken for warm-up can be shortened. In the following description, in order to avoid confusion with general overshoot, the increase in the surface temperature of the fixing roller due to heater control after the rotation of the fixing roller is stopped separately from the overshoot. Expressed as temperature rise due to stoppage.

  Here, returning to the flowchart of FIG. 7, the processing from step S113 will be described. In step S113, the control unit 106 determines whether or not the surface temperature value of the fixing roller 101 has reached the standby temperature value Tg (Tg2). If the surface temperature value of the fixing roller 101 has not reached the standby temperature value Tg (Tg2) (No in step S113), the control unit 106 determines the surface temperature value of the fixing roller 101 and the standby temperature value Tg (Tg2). The heater control unit 112 is instructed to control on / off of the heater 104 based on the temperature difference between the heater 104 and the heater 104. Upon receiving the instruction, the heater control unit 112 controls on / off of the heater 104 via the power supply unit 180, and until the surface temperature value of the fixing roller 101 reaches the standby temperature value Tg (Tg2), The surface temperature is controlled (step S115). On the other hand, when the surface temperature value of the fixing roller 101 has reached the standby temperature value Tg (Tg2), the controller 106 controls the heater control unit to keep the surface temperature value of the fixing roller 101 at the standby temperature value Tg (Tg2). An instruction is given to 112. Upon receiving the instruction, the heater control unit 112 controls on / off of the heater 104 so that the surface temperature value of the fixing roller 101 is maintained at the standby temperature value Tg (Tg2) (step S114). In addition, the process concerning step S113-step S115 has performed the feedback process demonstrated by the process of step S108. That is, in step S112, the heater 104 is not forcibly turned off, but the heater 104 is turned on / off based on the temperature difference between the surface temperature value of the fixing roller 101 and the standby temperature value Tg (Tg2). By performing the control, the time until the surface temperature value of the fixing roller 101 reaches the standby temperature value T (Tg2) g is shortened, and the time required for warm-up is shortened.

  As shown in FIG. 9A, in the section C, by performing the feedback control in the above steps S113 to S115, the temperature rise caused by the rotation of the fixing roller represented by the fixing roller temperature (T1) is fixed. Compared to the temperature increase when the rotation of the fixing roller represented by the roller temperature (T11) is continued without stopping, the time until the surface temperature value of the fixing roller 101 reaches the standby temperature value Tg is longer. Shorter. Similarly, as shown in FIG. 9-B, in the section C ′, the temperature associated with the rotation of the fixing roller represented by the fixing roller temperature (T2) is performed by performing the feedback control related to Step S113 to Step S115. The increase is that the surface temperature value of the fixing roller 101 reaches the standby temperature value Tg2 as compared to the temperature increase when the rotation of the fixing roller represented by the fixing roller temperature (T21) is continued without stopping. The time until is shortened.

  The magnitude of the temperature rise accompanying the rotation of the fixing roller is determined by the heat capacity and rotation speed of the fixing roller 101, and the time during which the heater is turned on between the start of warm-up and the stop of rotation of the roller. The temperature difference N determined in (1) is a temperature rise value accompanying the rotation stop of the fixing roller predicted in consideration of these conditions. Generally, the warm-up time varies depending on the environmental temperature value where the printer 1 is installed. This is because when the environmental temperature value is low, it takes a long time from the temperature at which the heater control is started until the temperature reaches the temperature until the rotation of the fixing roller is stopped. Therefore, in the present invention, as shown in FIGS. 9-A and 9-B, if the environmental temperature value is 20 ° C. or more, N1 if the environmental temperature value is 20 ° C. or more, N2 if it is less than 20 ° C., The relationship between N1 and N2 is N1 <N2. The temperature difference between N1 and N2 also has a magnitude relationship depending on the physical conditions of the fixing roller, for example, the heat capacity of the fixing roller.

The standby temperature value Tg varies depending on the thickness of the recording medium used for printing and the environment in which the apparatus is installed. Regarding the recording medium, in the case of plain paper (basis weight 64 g / m ^{2 to} 80 g / m ² ) generally used in offices, the standby temperature value Tg is about 170 ° C., and cardboard (basis weight 120 g / m ^{2 to} 200 g). / M ² ), the standby temperature value Tg is about 160 ° C. In the case of thick paper, the standby temperature value Tg is about 50% of that of plain paper, so the standby temperature value Tg can be set lower than that of plain paper. Regarding the environment, for example, the standby temperature value Tg when printing is performed at an environmental temperature value of 10 ° C. and the standby temperature value Tg when printing is performed at an environmental temperature value of 28 ° C. The standby temperature value Tg is set high. This is because the recording medium used is adapted to the same temperature value as the environment, so the recording medium passes through the fixing roller, and the passing recording medium takes the heat of the fixing roller, so the surface temperature value of the fixing roller decreases. However, this is because it is larger than the recording medium adapted to the environmental temperature value of 28 ° C.

  As described above, according to the first embodiment, the temperature difference N (= the amount of increase in temperature associated with the stop of rotation of the fixing roller) is set from the temperature value based on the temperature value information input from the environmental sensor, and the standby is performed. The warm-up time can be shortened by terminating the warm-up at a temperature lower than the temperature value. In addition, the time during which the heater is turned on has the effect of reducing power consumption by shortening the warm-up time. Furthermore, since the opportunity for the surface temperature value of the fixing roller to reach a temperature value higher than a specified value is reduced, it is possible to obtain an effect of extending the life of the fixing roller.

[Second Embodiment]
The configuration of the printer 1 ′ according to the second embodiment is substantially the same as the configuration of the printer 1 according to the first embodiment. Therefore, in the description of the printer 1 ′ according to the second embodiment, the same portions as those of the printer 1 according to the first embodiment are denoted by the same reference numerals, the description thereof is omitted, and different portions are described. .

  FIG. 11 is a diagram illustrating processing blocks of the printer 1 ′ according to the second embodiment. The control unit 106 ′ according to the second embodiment includes a medium information unit 142 in addition to the configuration according to the first embodiment.

  The medium information unit 142 holds medium information of the recording medium 2. This medium information setting method is performed by the user via the operation panel 118. Specifically, the user can select what media weight the recording medium 2 stored in the medium cassette 3 of the printer 1 ′ from the medium information list displayed on the display unit 119, for example, as shown in FIG. Is selected from the basis weight of the recording medium 2 and input. The medium information input by the user via the operation panel 118 is held in the medium information unit 142 via the operation panel control unit 117. The media weight information may be input from an external connection device such as the host computer 151 shown in FIG.

  Next, the processing operation of the printer 1 ′ will be described with reference to FIGS. 13 and 14. FIG. 13 is a flowchart for explaining a series of processing operations of the printer 1 ′. 14A is a diagram for explaining a temperature sequence when the recording medium 2 stored in the medium cassette 3 of the printer 1 ′ is plain paper, and FIG. 14B is stored in the medium cassette 3 of the printer 1 ′. It is a figure explaining the temperature sequence in case the recorded recording medium 2 is a cardboard.

  First, when the printer 1 'is turned on in step S201, the control unit 106' executes an initial process of the printer 1 '(step S202). The initial processing represents initialization of the control unit 106 including the CPU 107, the memory 109, the timer 110, and the like.

  Next, in step S203, the control unit 106 'reads the medium information from the medium information unit 142 that holds the medium information input by the user via the operation panel 118.

  Then, the control unit 106 'determines the temperature difference N based on the medium information read from the medium information unit 142 (step S204), and then determines the standby temperature value Tg (step S205).

  Next, the control unit 106 'stores the temperature difference N determined in step S204 and the standby temperature value Tg determined in step S205 in the memory 109 (step S206).

  Then, the control unit 106 'determines the fixing roller rotation stop temperature value Te3 (Te4) from the formula: Te3 (Te4) = Tg3 (Tg4) -N (step S207). Tg3 (Tg4) is a control target temperature value during standby of the printer 1 ′ (hereinafter also simply referred to as standby temperature value), and can be changed by the recording medium 2, the printing speed, and the heat capacity of the fixing roller 101. It is a temperature value. The temperature difference N is a temperature difference determined in step S204 and stored in the memory 109.

  Next, the control unit 106 'gives an instruction to the heater control unit 112 to control on / off of the heater 104 based on the determined fixing roller rotation stop temperature value Te3 (Te4). Upon receiving the instruction, the heater control unit 112 controls the surface temperature of the fixing roller 101 by controlling on / off of the heater 104 via the power supply unit 180 (step S208).

  Note that the control method by the heater control unit 112 sets the standby temperature value Tg3 (Tg4) as a control target, and sets temperature difference information between the standby temperature value Tg3 (Tg4) and the current surface temperature value of the fixing roller 101 at predetermined time intervals. Are sequentially read out, and feedback control for controlling the on-time / off-time of the heater 104 based on the temperature difference information. In this feedback control, the temperature difference component between the standby temperature value Tg3 (Tg4) and the current surface temperature value of the fixing roller 101 is P, the gradient component between the current temperature difference and the temperature difference one processing step before is D, and the current The cumulative component of the temperature difference in the past for a predetermined time is I, and the value calculated from the constants Kp, Kd, Ki multiplied by the values of P, D, I (Kp * P + Kd * D + Ki * I) This is a control method for determining the ON time and OFF time of the heater 104 from the comparison result with a predetermined threshold value. The constants Kp, Kd, and Ki are values determined from various parameters such as the physical heat capacity of the fixing roller 101, the capacity of the heater 104, and the rotation amount of the fixing roller 101. These values are not always fixed and are controlled. It is a value that can be set as appropriate depending on the application.

  Here, the temperature sequence shown in FIGS. 14A and 14B will be described. 14A and 14B, t0 '' and t0 '' '' indicate the time when the main power supply of the printer 1 'is turned on. Further, t ″ 1, t1 ″ ′ are times when the control (heater ON) of the heater 104 is started, and t2 ″ and t2 ′ ″ are the surface temperature values of the fixing roller 101 set to the fixing roller rotation start temperature values Tr3, Tr4. The surface temperature value of the fixing roller 101 reaches the fixing roller rotation stop temperature values Te3 and Te4 at the time when the rotation of the fixing roller 101 starts and t3 ″ and t3 ′ ″. The stop time, t ″ 4, t4 ′ ″, represents the time when the surface temperature value of the fixing roller 101 reaches the standby temperature values Tg3, Tg4.

  In the sections A ″, A ′ ″ (t1 ″ −t2 ″, t1 ′ ″ − t2 ′ ″) as the first warm-up control section, the rotation of the fixing roller 101 is stopped. The heater is continuously on. Similarly, the rotation of the fixing roller 101 is started in the sections B ″, B ′ ″ (t2 ″ −t3 ″, t2 ″ ′ − t3 ′ ″) as the first warm-up control section. The heater is continuously on.

  In the sections C ″, C ′ ″ (t3 ″ −t4 ″, t3 ′ ″ − t4 ′ ″) as the second warm-up control section, the rotation of the fixing roller 101 is stopped. The heater is intermittently on. Further, in the sections D ″, D ′ ″ (after t4 ″, after t4 ′ ″) as the standby control section, the rotation of the fixing roller 101 is stopped and the heater is intermittently turned on. .

  14A and 14B, the warm-up start timing is in the vicinity of 20 ° C. When the standby temperature values Tg3 and Tg4 that are control targets in the present embodiment are 170 ° C., in step S208 There is a temperature difference of about 150 ° C. at the start of control of the heater 104. Therefore, the control unit 106 ′ instructs the heater control unit 112 to turn on the heater 104. When the heater 104 is turned on based on the control of the heater control unit 112, the surface temperature value of the fixing roller 101 starts to rise as shown in FIGS. 14A and 14B.

  Next, in step S209, the control unit 106 'determines whether or not the surface temperature value of the fixing roller 101 that has started to rise has reached Tr3 (Tr4) that is the fixing roller 101 rotation start temperature value. Here, when the surface temperature value of the fixing roller 101 does not reach Tr3 (Tr4) (No in step S209), the control unit 106 'repeats the determination. On the other hand, when the surface temperature value of the fixing roller 101 has reached Tr3 (Tr4) (step S209 Yes), the fixing control unit 141 instructs the motor drive control unit 113 to start the rotation of the fixing unit rotation mechanism 173. give. Upon receiving the instruction, the motor drive control unit 113 outputs a rotation start signal to the motor 131, and the motor 131 starts rotating. The rotation of the motor 131 is transmitted to the fixing unit rotation mechanism 173 via the drive transmission unit 172, and the fixing roller 101 starts to rotate (step S210).

  Next, the control unit 106 'determines whether or not the surface temperature value of the fixing roller 101 has reached Te3 (Te4) that is the fixing roller rotation stop temperature value (step S211). Here, when the surface temperature value of the fixing roller 101 does not reach Te3 (Te4) (No in step S211), the control unit 106 'repeats the determination. On the other hand, when the surface temperature value of the fixing roller 101 has reached Te3 (Te4) (Yes in step S211), the fixing control unit 141 instructs the motor drive control unit 113 to stop the fixing unit rotation mechanism 173 from rotating. give. Upon receiving the instruction, the motor drive control unit 113 outputs a rotation stop signal to the motor 131, and the motor 131 stops rotating. With the rotation of the motor 131 stopped, the fixing roller 101 stops rotating (step S212).

  In step S213, the control unit 106 'determines whether or not the surface temperature value of the fixing roller 101 has reached the standby temperature value Tg3 (Tg4). Here, when the surface temperature value of the fixing roller 101 does not reach the standby temperature value Tg3 (Tg4) (No in step S213), the control unit 106 ′ determines the surface temperature value of the fixing roller 101 and the standby temperature value Tg3 (Tg4). The heater control unit 112 is instructed to control on / off of the heater 104 based on the temperature difference from Upon receiving the instruction, the heater control unit 112 controls on / off of the heater 104 via the power supply unit 180, and until the surface temperature value of the fixing roller 101 reaches the standby temperature value Tg3 (Tg4), The surface temperature is controlled (step S215). On the other hand, when the surface temperature value of the fixing roller 101 has reached the standby temperature value Tg3 (Tg4), the control unit 106 ′ controls the heater so as to keep the surface temperature value of the fixing roller 101 at the standby temperature value Tg3 (Tg4). An instruction is given to the unit 112. Upon receiving the instruction, the heater control unit 112 controls on / off of the heater 104 so that the surface temperature value of the fixing roller 101 is maintained at the standby temperature value Tg3 (Tg4) (step S214). In addition, the process concerning step S213-step S215 is performing the feedback process demonstrated by the process of step S208. That is, in step S212, the heater 104 is not forcibly turned off, but the heater 104 is turned on / off based on the temperature difference between the surface temperature value of the fixing roller 101 and the standby temperature value Tg3 (Tg4). By performing the control, the time until the surface temperature value of the fixing roller 101 reaches the standby temperature value Tg3 (Tg4) is shortened, and the time required for warm-up is shortened.

  As described in the first embodiment, the magnitude of the temperature rise accompanying the rotation stop of the fixing roller is determined by the rotation speed of the fixing roller 101 and the time when the heater is turned on between the start of warm-up and the stop of roller rotation. Is done. Therefore, when the media weight is “plain paper” and “standby temperature value Tg = 170 ° C.” and when the media weight is “thick paper” and “standby temperature value Tg = 160 ° C.”, the standby that is set as the control target is set. Since the temperature values Tg are different, the time from the start of warm-up to the stop of roller rotation is different. Generally, the type of recording medium used for printing, for example, a recording medium having a large paper thickness, requires a large amount of heat necessary for fixing. That is, when the rotation speed of the fixing roller 101 is constant, a high fixing temperature is required for a recording medium having a large paper thickness. However, in order to realize a high fixing temperature, a large amount of electric power is required, which causes a problem that power consumption increases. For this reason, in a recording medium with a large paper thickness, the rotation speed of the fixing roller 101 may be slowed, and the fixing temperature may be set lower at that time. In this case, since the standby temperature value Tg is also set low, the time for which the heater is turned on is also shortened. For this reason, the roller rotation stop temperature is lowered under a setting in which the rotation speed of the fixing roller 101 is decreased and the standby temperature is lowered. For this reason, N1 and N2 of the temperature difference N shown in FIGS. 14A and 14-B have a relationship of N1> N2, and N1 and N2 of the temperature difference N are set in step S204. In FIG. 5, the temperature rise amount due to the rotation stop of the fixing roller predicted to occur after the warm-up is completed.

  In this embodiment, the standby temperature value Tg and the temperature difference N are set based on the media weight information input by the user. However, as described in the first embodiment, the apparatus is installed. Since the standby temperature value Tg can be arbitrarily changed according to the environmental temperature value, various standby temperature values Tg and temperature differences N can be set according to the media weight information and the environmental temperature value.

  As described above, according to the second embodiment, since the standby temperature value as the control target can be set based on the information of the recording medium stored in the medium tray, for each recording medium used for printing It is possible to shorten the warm-up time. Further, by shortening the warm-up time, the time for turning on the heater can be shortened, so that power consumption can be suppressed. Furthermore, since the opportunity for the surface temperature value of the fixing roller to reach a temperature value higher than a specified value is reduced, it is possible to obtain an effect of extending the life of the fixing roller.

  In the embodiment according to the present invention, the printer is described as an example of the image forming apparatus. However, the present invention can be applied to, for example, an MFP (Multi Function Peripheral), a facsimile, a copying apparatus, and the like in addition to the printer. Is possible.

FIG. 3 is a side cross-sectional view for explaining a main configuration of the printer. It is a figure explaining a fixing unit. It is a figure explaining a fixing unit. It is a figure explaining the example of arrangement | positioning of a roller temperature detection element. 2 is a block diagram illustrating a functional configuration of a printer. FIG. It is a figure explaining the processing block of a printer. 6 is a flowchart illustrating a series of processing operations of the printer. It is an example of the list | wrist for determining the temperature difference N. It is a figure explaining a temperature sequence. It is a figure explaining a temperature sequence. It is a figure explaining overshoot. It is a figure explaining the processing block of a printer. It is an example of a list of medium information. 6 is a flowchart illustrating a series of processing operations of the printer. It is a figure explaining a temperature sequence. It is a figure explaining a temperature sequence.

Explanation of symbols

1, 1 'Printer 2 Recording medium 3 Media cassette 11, 12, 13, 14 Process unit 20 Transfer belt 21, 22, 23, 24 Transfer roller 30 Fixing unit 40, 41 Pickup roller 42 Registration roller 43, 44 Conveying roller 45 Addition Pressure roller 46 Fixing roller 47, 48 Discharge roller 51, 52, 53 Medium passing sensor 101 Fixing roller 102 Roller temperature detecting element 104 Heater 105 Endless belt 106, 106 'Controller 107 CPU
108 ROM
DESCRIPTION OF SYMBOLS 109 Memory 110 Timer 111 External interface 112 Heater control part 113 Motor drive control part 115 Fixing part temperature detection part 116 Temperature comparison part 117 Operation panel control part 118 Operation panel 119 Display part 121 Medium passage sensor 130 Connection connector 131 Motor 141 Fixing control part 142 Media information section 150 I / F
151 Host computer 161 Roller 162 Temperature detection element 165 Pressure unit temperature detection unit 166 A / D conversion unit 167 Environmental sensor 172 Drive transmission unit 173 Fixing unit rotation mechanism 180 Power supply unit

Claims (10)

An image forming apparatus that heat-fixes an image recording medium to which a developer image is transferred,
A heat source,
A fixing unit heated by the heat source;
A pressure unit disposed opposite to the fixing unit and pressing the fixing unit;
A temperature detection unit that is disposed in a medium passing area of the fixing unit and detects a temperature value of the fixing unit;
A rotation control unit that controls rotation of the fixing unit and the pressure unit;
With
The rotation control unit
When the detected temperature value of the fixing unit detected by the temperature detecting unit reaches a temperature value lower than a preset standby temperature value by a predetermined temperature value, the rotation of the fixing unit and the pressing unit is stopped. Letting
An image forming apparatus. It has an environmental temperature detector that detects the environmental temperature value.
The predetermined temperature value is
Being changed based on the detection result of the environmental temperature value by the environmental temperature detection unit,
The image forming apparatus according to claim 1. A medium information holding unit for holding the inputted medium information;
The standby temperature value and the predetermined temperature value are:
Being changed based on the medium information held in the medium information holding unit;
The image forming apparatus according to claim 1. An image forming apparatus that heat-fixes an image recording medium to which a developer image is transferred,
A heat source,
An energization control unit for controlling energization to the heat source;
A fixing unit heated by the heat source based on control by the energization control unit;
A temperature detection unit that is disposed in a medium passing area of the fixing unit and detects a temperature value of the fixing unit;
A rotation control unit for controlling rotation of the fixing unit;
With
Based on the detection result of the temperature value of the fixing unit by the temperature detection unit,
When the temperature is not less than the first temperature value and less than the second temperature value, the energization control unit controls the heat source to energize the fixing unit, and the rotation control unit controls the rotation of the fixing unit,
When the temperature is greater than or equal to the second temperature value and less than the third temperature value, the energization control unit controls the heat source to energize the fixing unit, and the rotation control unit controls the rotation of the fixing unit to stop. To do,
An image forming apparatus characterized by The first temperature value is
A set temperature value serving as an index of timing when the rotation control unit starts rotation of the fixing unit;
The image forming apparatus according to claim 4. The second temperature value is
A set temperature value serving as an index of timing when the rotation control unit stops the rotation of the fixing unit;
The image forming apparatus according to claim 4, wherein: The third temperature value is
A set temperature value serving as an index of timing for starting the heat fixing of the image recording medium to which the developer image has been transferred;
The image forming apparatus according to claim 4, wherein the image forming apparatus is an image forming apparatus. Until the first temperature value is reached,
The energization control unit controls the heat source to energize the fixing unit, and the rotation control unit controls the rotation of the fixing unit to stop.
The image forming apparatus according to claim 4, wherein the image forming apparatus is an image forming apparatus. The temperature difference between the second temperature value and the third temperature value is
Set based on the ambient temperature,
The image forming apparatus according to claim 4, wherein the image forming apparatus is an image forming apparatus. The temperature difference between the second temperature value and the third temperature value is
The lower the environmental temperature, the larger the setting,
The image forming apparatus according to claim 9.