JP2008102279A - Fixing apparatus, image forming apparatus using the same, and fixing method - Google Patents

Abstract

A fixing device that can complete warm-up earlier, improve durability, and reduce fixing unevenness after warm-up, and an image forming apparatus and a fixing method using the same are provided.
A fixing roller T having a heating roller 172 having a fixing roller heating device H, a pressure roller 173 forming a nip portion facing the heating roller 172, and an environment sensor 8 for measuring the surrounding environment. And a control device 11 for controlling the rotation speed of the fixing roller T during the warm-up according to the measured value of the environmental sensor 8.
[Selection] Figure 2

Description

  In particular, the present invention relates to a fixing device that controls the rotation speed of a fixing rotator during warm-up, an image forming apparatus using the fixing device, and a fixing method.

  In general, an electrophotographic toner image forming unit includes a photosensitive member as an image bearing member having a photosensitive layer on an outer peripheral surface, a charging unit that uniformly charges the outer peripheral surface of the photosensitive member, and a uniform charging unit using the charging unit. An exposure unit that selectively exposes the outer peripheral surface charged to form an electrostatic latent image, and a toner as a developer is applied to the electrostatic latent image formed by the exposure unit to form a visible image ( Developing means for forming a toner image).

  As a rotary type image forming apparatus for forming a color image, the toner image forming means as described above is arranged on the intermediate transfer belt. The toner images on the photoconductor by these toner image forming means are sequentially transferred to an intermediate transfer belt, and a plurality of toner images (for example, yellow, cyan, magenta, black (black)) are superimposed on the intermediate transfer belt, There is an intermediate transfer belt type that obtains a color image on an intermediate transfer belt.

In such an image forming apparatus, conventionally, when the fixing temperature is reached by controlling the heater driver and the roller driving unit so as to heat the fixing roller while rotating the fixing roller at a predetermined rotational speed during warm-up. Since the temperature difference between the peripheral surfaces of the fixing roller is small, there is a fixing device that shortens the time from the start of warm-up until fixing can be performed without causing image quality defects such as gloss unevenness and fixing failure. (See Patent Document 1).
JP-A-10-213987

  By the way, in the fixing device, unevenness at the time of fixing becomes a problem when there is a lot of moisture in the paper with poor fixability and when the temperature of the paper is low. In this case, the rotation at the time of warm-up must be made sufficiently long, and the deterioration is accelerated by driving the rotation for a long time.

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to fix fixing that can complete warm-up earlier, improve durability, and reduce fixing unevenness after warm-up. An apparatus, an image forming apparatus using the apparatus, and a fixing method are provided.

  The fixing device of the present invention that achieves the above object includes a fixing roller having a heating roller having a fixing roller heating device, a pressure roller that forms a nip portion facing the heating roller, and an environment for measuring the surrounding environment. And a control device that controls the rotation speed of the fixing roller during the warm-up according to the measured value of the environmental sensor. And the unevenness of fixing after warm-up can be reduced.

  In addition, since the control device controls the measurement value of the environmental sensor based on a table in which the rotation speed of the fixing roller during warm-up is set, there is no need to perform calculation. Responsiveness is improved.

  A heating roller temperature sensor for measuring the temperature of the heating roller; and a pressure roller temperature sensor for measuring the temperature of the pressure roller. The control device includes the environmental sensor and the heating roller temperature sensor. And it controls according to the measured value of the said pressure roller temperature sensor, Therefore A more precise control can be performed.

  In addition, since the control device sets the target temperature of the heating roller and the target temperature of the pressure roller according to the measured value of the environmental sensor, more precise control can be executed. it can.

  In addition, since the control device performs setting of the target temperature of the heating roller and the target temperature of the pressure roller with respect to the measured value of the environmental sensor based on a table, it is necessary to perform calculation. There is no response.

  In addition, since the control device controls the heating roller and the pressure roller so as to reach the respective target temperatures almost simultaneously, the control at the time of warming up can be executed earlier.

  Further, since the environmental sensor is a humidity sensor that measures the humidity of the surrounding atmosphere and a temperature sensor that measures the temperature of the surrounding atmosphere, more precise control can be executed.

  Further, the control device is characterized in that the lower the measured value of the humidity sensor, the slower the rotation speed of the fixing roller, so that more precise control can be executed.

  Further, the control device is characterized in that the higher the measured value of the temperature sensor, the slower the rotation speed of the fixing roller, so that more precise control can be executed.

  An image forming apparatus using the fixing device of the present invention includes an image carrier, a developer carrier that develops a latent image on the image carrier, and the image carrier developed by the developer carrier. An intermediate transfer member that transfers the image on the image, a secondary transfer unit that transfers the image on the intermediate transfer member to a transfer material, and the fixing device that fixes the image on the transfer material. Therefore, warm-up can be completed earlier, durability can be improved, and fixing unevenness after warm-up can be reduced.

  Further, the fixing method of the present invention includes a step of measuring an ambient environment, a step of determining and driving a warm-up rotation speed of the fixing roller according to the measured ambient environment, and a heating roller and a pressure roller of the fixing roller. And the step of driving until the temperature reaches the set temperature, so that warm-up can be completed earlier, durability can be improved, and uneven fixing after warm-up can be reduced. .

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view of the fixing device of this embodiment. In the figure, 1 is a fixing device, 172 is a heating roller, 173 is a pressure roller, 4 is a housing, 5 is an inlet side guide, 6 is an outlet side guide, 7 is a peeling member, and H is an example of a fixing roller heating device. A heater T is a fixing roller.

  The fixing device 1 includes a heating roller 172, a pressure roller 173, a housing 4, an inlet side guide 5, an outlet side guide 6, a peeling member 7, and the like. The heating roller 172 is supported by a cylindrical member with a built-in heater H so as to be rotatable at both ends, and is driven by a driving device (not shown). The pressure roller 173 is provided in parallel with the heating roller 172 and is driven, and forms a nip portion to press the sheet S toward the heating roller 172. The housing 4 supports the heating roller 172, the pressure roller 173, the housing 4, the inlet side guide 5, the outlet side guide 6, and the peeling member 7. The inlet side guide 5 and the outlet side guide 6 are guides for guiding the paper S on the inlet side and the outlet side, respectively. The peeling member 7 is a member that peels off the paper S that is in close contact with the heating roller 172.

  The operation of the fixing device 1 having such a structure will be briefly described. The sheet S passes through the entrance-side guide 5 and passes through the nip portion between the heating roller 172 and the pressure roller 173. After passing through the nip portion, the sheet S that is in close contact with the heating roller 172 is peeled off from the heating roller 172 by the peeling member 7, passes through the outlet side guide 6, and goes downstream.

  FIG. 2 is a block diagram of the fixing device. In the figure, 8 is an environmental sensor, 8a is a humidity sensor, 8b is a temperature sensor, 9 is a heating roller temperature sensor, 10 is a pressure roller temperature sensor, 11 is a control device, 12 is a fixing roller rotation driving device, and H is a fixing roller. It is a heater as an example of a heating apparatus.

  The environmental sensor 8 includes a humidity sensor 8a, a temperature sensor 8b, and the like, and is a sensor that measures the state of the surrounding environment. The heating roller temperature sensor 9 is a sensor that detects the surface temperature of the heating roller 172, and a pressure roller temperature sensor. Reference numeral 10 denotes a sensor that detects the surface temperature of the pressure roller 173. The control device 11 receives the detection result from each sensor and controls the rotation speed of the fixing roller rotation driving device 12 and the temperature of the heater H.

  FIG. 3 is a graph showing the relationship between the surface temperature and the time during warm-up of the heating roller 172 and the pressure roller 173 having different rotational speeds in the fixing device having such a configuration. As shown in FIG. 3, the temperature of the heating roller 172 is higher in a shorter time when rotated at 120 rpm than at 160 rpm, and the pressure roller 173 is rotated at 120 rpm when rotated at 160 rpm. The temperature increases in a shorter time.

  For example, if the target temperature of the heating roller 172 is 160 ° C. and the target temperature of the pressure roller 173 is 120 ° C., both the heating roller 172 and the pressure roller 173 reach the target temperature in about 50 seconds when rotated at 160 rpm. However, when rotated at 120 rpm, the pressure roller 173 reaches the target temperature in about 55 seconds, even though the heating roller 172 reaches the target temperature in about 40 seconds. Therefore, when the target temperature of the heating roller 172 is 160 ° C. and the target temperature of the pressure roller 173 is 120 ° C., the target arrival time is shorter when rotated at 160 rpm than at 120 rpm.

  FIG. 4 shows a flowchart of warm-up control of this fixing device. First, in step 1, the environmental humidity and the environmental temperature are measured by the humidity sensor 8a and the temperature sensor 8b as the environmental sensor 8 (ST1). Next, in step 2, the warm-up rotation speed of the heating roller 172 is determined (ST2). The relationship between the environmental humidity and the environmental temperature and the warm-up rotation speed is set by the table shown in Table 1.

  As shown in Table 1, the control device 11 decreases the rotation speed of the fixing roller T as the measured value of the humidity sensor 8a decreases, and decreases the rotation speed of the fixing roller T as the measured value of the temperature sensor 8b increases. In this manner, the fixing roller rotation driving device 12 is controlled.

  As described above, in this embodiment, a table of the relationship between the environmental humidity and the environmental temperature and the warm-up rotation speed is held in advance, and the control device 11 sets the warm-up rotation speed using this table in step 2. In the present embodiment, since the table of the relationship between the environmental humidity and the environmental temperature and the warm-up rotation speed is held, the responsiveness is improved. If responsiveness is not important, it may be obtained by calculation.

  Next, in Step 3, the heating roller 172 is rotationally driven by the fixing roller rotation driving device 12 at the rotational speed determined in Step 2, and the heater H is turned on to start warming up the fixing roller T (ST3). Next, in step 4, the temperatures of the heating roller 172 and the pressure roller 173 are measured by the heating roller temperature sensor 9 and the pressure roller temperature sensor 10, respectively (ST4).

  Subsequently, in step 5, it is determined whether the temperature of the heating roller 172 and the pressure roller 173 has reached a predetermined target temperature (ST5). When the temperature of the heating roller 172 and the pressure roller 173 does not reach the predetermined target temperature, the process returns to step 4 and the temperature of the heating roller 172 and the pressure roller 173 is measured. When the temperature of the heating roller 172 and the pressure roller 173 reaches a predetermined target temperature, the warm-up is finished.

  Here, the control device 11 can execute more precise control by setting the target temperature of the heating roller 172 and the target temperature of the pressure roller 173 in accordance with the measurement value of the environment sensor 8. Further, when the control device 11 performs control according to the measured values of the environment sensor 8, the heating roller temperature sensor 9, and the pressure roller temperature sensor 10, more precise control can be executed. Further, at that time, it is preferable that the control device 11 can control the heating roller 172 and the pressure roller 173 so as to reach the respective target temperatures almost simultaneously. In the present embodiment, the control device 11 performs setting of the target temperature of the heating roller 172 and the target temperature of the pressure roller 172 with respect to the measurement value of the environment sensor 8 based on the table, so that the responsiveness is improved. If responsiveness is not important, it may be obtained by calculation.

  FIG. 5 is a vertical side view of an image forming apparatus to which the present invention is applied. In FIG. 5, the image forming apparatus 160 includes, as main constituent members, a rotary developing device 161, a photosensitive drum 165 functioning as an image carrier, and an image writing unit (line head) 167 provided with an organic EL array. An intermediate transfer belt 169 as an intermediate transfer member, a paper transport path 174, a heating roller 172 of a fixing device, and a paper feed tray 178 are provided.

  In the developing device 161, the developing rotary 161a rotates in the arrow A direction about the shaft 161b. The inside of the development rotary 161a is divided into four, and image forming units for four colors of yellow (Y), cyan (C), magenta (M), and black (K) are provided. Reference numerals 162a to 162d are arranged in the image forming units of the four colors, and developing rollers as toner carriers that rotate in the direction of arrow B, and 163a to 163d are toner supply rollers that rotate in the direction of arrow C. is there. Reference numerals 164a to 164d are regulating blades that regulate the toner to a predetermined thickness.

  The photosensitive drum 165 is driven in the direction of arrow D opposite to the developing roller 162a by a drive motor (not shown), for example, a step motor. The intermediate transfer belt 169 is stretched between the driven roller 170b and the drive roller 170a, and the drive roller 170a is connected to the drive motor of the photosensitive drum 165 to transmit power to the intermediate transfer belt 169. By driving the drive motor, the drive roller 170 a of the intermediate transfer belt 169 is rotated in the arrow E direction opposite to the photosensitive drum 165.

  The operation from the image forming apparatus 160 developing apparatus 161 having such a structure to the intermediate transfer belt 169 will be described. First, toner is supplied from the toner supply roller 163 to the developing roller 162. At this time, the toner amount is adjusted by the regulating blade 164. The developing roller 162 develops the latent image on the photosensitive drum 165 formed by the line head 167 or the like. The image on the photosensitive drum 165 is transferred to the intermediate transfer belt 169.

  The paper conveyance path 174 is provided with a plurality of conveyance rollers, a pair of paper discharge rollers 176, and the like, and conveys the paper. An image (toner image) on one side carried on the intermediate transfer belt 169 is transferred to one side of the paper at the position of the secondary transfer roller 171. The secondary transfer roller 171 is separated from and brought into contact with the intermediate transfer belt 169 by a clutch, and is brought into contact with the intermediate transfer belt 169 when the clutch is turned on, so that an image is transferred onto the sheet.

  The sheet on which the image has been transferred as described above is then subjected to a fixing process by the fixing device having the fixing heater H described above. The fixing device is provided with a heating roller 172 and a pressure roller 173 having an inverted crown shape. The sheet after the fixing process is drawn into the discharge roller pair 176 and proceeds in the arrow F direction. When the paper discharge roller pair 176 rotates in the opposite direction from this state, the paper reverses its direction and advances in the double-sided printing conveyance path (double-sided conveyance path) 175 in the arrow G direction. Reference numeral 183 denotes a first double-sided roller, and 184 denotes a second double-sided roller. 177 is an electrical component box, 178 is a paper feed tray for storing paper, and 179 is a pickup roller provided at the outlet of the paper feed tray 178. An exhaust fan 191 is provided in the housing case 190. An opening / closing door 190a is provided on the side of the paper transport path 174 of the housing case 190 to pull out paper at the time of jam.

  A feed roller 181 is provided in the single-sided sheet conveyance path 174 on the downstream side as viewed from the sheet conveyance direction of the pickup roller 179. A gate roller 180 is disposed on the upstream side of the secondary transfer roller 171.

  In the example of FIG. 5, a line head using a light emitting element is provided as an exposure unit, but a scanning optical system using laser light may be provided as a light source.

  As described above, the fixing device of the present embodiment, the image forming apparatus and the image forming method using the fixing device, can complete warm-up at an early stage, improve durability, and reduce fixing unevenness after warm-up. it can.

  The fixing device according to the embodiments of the present invention, the image forming apparatus using the fixing device, and the image forming method using the fixing device have been described above, but the present invention is not limited to these embodiments and can be variously modified.

It is a vertical side view showing the fixing device of the present embodiment. 1 is a block diagram of a fixing device according to an exemplary embodiment. It is a figure which shows the relationship between time and temperature of the fixing device of this embodiment. FIG. 3 is a diagram illustrating a flowchart of the fixing device of the present embodiment. 1 is a longitudinal side view illustrating an embodiment of an image forming apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Fixing device, 4 ... Housing, 5 ... Inlet side guide, 6 ... Outlet side guide, 7 ... Release member, 8 ... Environmental sensor, 8a ... Humidity sensor, 8b ... Temperature sensor, 9 ... Heating roller temperature sensor, 10 ... Pressure roller temperature sensor 11... Control device 12 Fixing roller rotation drive device 160 Image forming device 161 Development device 165 Photosensitive drum (image carrier) 169 Intermediate transfer belt (intermediate transfer member) , 171 ... Secondary transfer roller (secondary transfer part), 172 ... Heating roller, H ... Heater, 173 ... Pressure roller, T ... Fixing roller

Claims (11)

  A fixing roller having a heating roller having a fixing roller heating device, a pressure roller that forms a nip portion facing the heating roller, and an environmental sensor that measures the surrounding environment, and the measured value of the environmental sensor A fixing device comprising a control device for controlling the rotation speed of the fixing roller during warm-up according to the above.   The fixing device according to claim 1, wherein the control device performs control based on a table in which a rotation speed of the fixing roller during warm-up is set with respect to a measurement value of the environment sensor.   A heating roller temperature sensor that measures the temperature of the heating roller; and a pressure roller temperature sensor that measures the temperature of the pressure roller. The control device includes the environmental sensor, the heating roller temperature sensor, and the The fixing device according to claim 1, wherein the fixing device is controlled in accordance with a measurement value of a pressure roller temperature sensor.   The said control apparatus sets the target temperature of the said heating roller and the target temperature of the said pressure roller according to the measured value of the said environmental sensor, respectively, The Claim 1 thru | or 3 characterized by the above-mentioned. Fixing device.   5. The fixing device according to claim 4, wherein the control device executes setting of a target temperature of the heating roller and a target temperature of the pressure roller with respect to a measured value of the environment sensor based on a table.   The fixing device according to claim 4, wherein the control device controls the heating roller and the pressure roller to reach their target temperatures substantially simultaneously.   The fixing device according to claim 1, wherein the environmental sensor is a humidity sensor that measures the humidity of the surrounding atmosphere and a temperature sensor that measures the temperature of the surrounding atmosphere.   The fixing device according to claim 7, wherein the control device slows down the rotation speed of the fixing roller as the measured value of the humidity sensor is lower.   The fixing device according to claim 7, wherein the control device slows down the rotation speed of the fixing roller as the measured value of the temperature sensor is higher.   An image carrier, a developer carrier that develops a latent image on the image carrier, an intermediate transfer member that transfers an image on the image carrier developed by the developer carrier, and the intermediate transfer member The fixing device according to claim 1, further comprising: a secondary transfer portion that transfers the image on the transfer material, and the fixing device that fixes the image on the transfer material. An image forming apparatus using the apparatus.   A step of measuring the surrounding environment, a step of determining and driving the warm-up rotation speed of the fixing roller according to the measured surrounding environment, and driving until the temperature of the heating roller and the pressure roller of the fixing roller reaches a set temperature. And a fixing method.

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