JP2017090663A - Fixing device and image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a stable image quality by promoting lower thermal capacity, shorter recovery time, and reduced temperature ripple.SOLUTION: A fixing device includes a fixing member 40 for fixing a non-fixing toner to a sheet P, a heating source 50 for heating the fixing member 40, a pressurizing member 30 for pressurizing the sheet P against the fixing member 40, a nip formation member 60 for forming a nip against the pressurizing member 30, an electric power control circuit 70 which controls a power supply to the heating source 50, and a pressurizing temperature detection sensor S1 for detecting temperature of the pressurizing member 30. It includes power supply correction means 80a which, according to a pressurizing temperature that is detected with the pressurizing temperature detection sensor S1, corrects for increase/decrease of power supply to the heating source 50 and corrects for advance/delay of an expected power supply timing.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a fixing device for fixing an unfixed toner image and an image forming apparatus using the same.

  In recent years, market demands for energy saving and high speed are increasing for image forming apparatuses such as printers, copiers, and facsimiles. In the image forming apparatus described above, an unfixed toner image is transferred to a recording material sheet, printing paper, photosensitive paper, electrostatic recording by an image transfer method or a direct method by an image forming process such as electrophotographic recording, electrostatic recording, or magnetic recording. It is formed on a recording medium such as paper (hereinafter referred to as “paper”).

  Incidentally, in the image forming apparatus described above, a fixing device for fixing an unfixed toner image is used. As such a fixing device, a contact heating method such as a heat roller method, a film heating method or an electromagnetic induction heating method is adopted.

  Examples of the fixing device described above include those disclosed in Patent Documents 1 and 2. The fixing device disclosed in Patent Document 1 is of a belt type, and further reduction in warm-up time and first print time is desired (Problem 1). “Warm-up time” refers to the time required from a normal temperature state to a predetermined printable temperature (reload temperature) such as when the power is turned on. The “first print time” refers to the time from when a print request is received to when the print operation is performed through the print preparation and the paper discharge is completed.

  Further, as the speed of image forming apparatuses increases, the number of sheets that pass through per unit time increases, and the amount of heat required increases. For this reason, there is a problem that the amount of heat is insufficient (so-called temperature drop) at the beginning of continuous printing (problem 2).

  The fixing device disclosed in Patent Document 2 is of the surf fixing (film fixing) type using a ceramic heater. By adopting this surf fixing method, the heat capacity is reduced and the size is reduced as compared with the belt type fixing device described above. Can be realized. However, in the surf fixing method, since only the nip portion is locally heated, the other portions are not heated, and the belt is in the coldest state at the entrance of the paper or the like of the nip, and fixing failure is likely to occur. There is a problem of becoming. In particular, in the high-speed processing in which the belt rotates fast and the heat radiation of the belt outside the nip portion increases, there is a problem that fixing defects are more likely to occur (Problem 3).

  For the purpose of solving the above problems 1 to 3, there is a configuration disclosed in Patent Document 3 in the name of a heating device. FIG. 5 is a schematic cross-sectional view showing a schematic configuration of the heating device disclosed in Patent Document 3. As shown in FIG. The heating device shown in FIG. 5 fixes a pipe-shaped metal heat conductor 2 inside the endless belt 1 so as to guide the movement of the endless belt 1, and the metal heat conductor 2 provides a heat source inside thereof. 3, the endless belt 1 is indirectly heated.

  In addition, a pressure roller 4 that forms a nip portion N in contact with the metal heat conductor 2 via the endless belt 1 is provided, and the endless belt 1 is rotated so as to rotate as the pressure roller 4 rotates. Move in the direction. Reference numeral 5 denotes a metal roller, and reference numeral 6 denotes an elastic layer.

  That is, the heating device disclosed in Patent Document 3 is configured to warm the entire endless belt 1 in the configuration using the endless belt 1. According to this configuration, it is possible to shorten the first print time from the standby time of heating, and solve the shortage of heat during the high-speed rotation processing, so that excellent fixing even when mounted on a high-production image forming apparatus It is possible to obtain sex.

  However, in the heating device disclosed in Patent Document 3, although the above-described first print time can be shortened, it is necessary to further improve the thermal efficiency in order to further improve the energy saving and the first print time. is there.

  In each of the above conventional fixing devices and the like, by adopting a configuration in which the endless belt 1 is directly heated, energy saving is high, and the first print time from the heating standby time can be further shortened. On the other hand, it has become clear that the temperature controllability deteriorates due to the temperature of the pressure roller itself that does not have a heater, which was not a problem in the past. That is, when the sheet passes through the nip when the pressurizing temperature is high, the power supplied to the fixing member until just before that is small. When the sheet passes through the nip in this state, the temperature of the pressure roller is drastically decreased. As a result, the temperature of the fixing member being controlled is lowered more than necessary, and a drop occurs. This causes a temperature ripple, and the temperature controllability for a few seconds thereafter deteriorates. On the other hand, when the pressurization temperature is low, the pressurization temperature does not drop so much even when the paper passes, and a relatively large electric power is supplied until immediately before the pressurization temperature.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a fixing device capable of obtaining a stable image quality by reducing a temperature ripple as well as reducing a heat capacity and shortening a recovery time, and an image forming apparatus using the same.

  According to a first aspect of the present invention for solving the above problem, a fixing member for fixing unfixed toner to a recording medium, a heating source for heating the fixing member, and the fixing member are provided. A pressure member that pressurizes the recording medium, a nip forming member that forms a nip between the pressure member, a power control circuit that controls power supplied to the heating source, and a temperature of the pressure member In the fixing device having the pressurizing temperature detecting sensor, the power supply to the heating source is corrected to increase or decrease according to the pressurizing temperature detected by the pressurizing temperature detecting sensor, and the expected power supply timing is delayed. It is characterized by having a power supply correcting means for correcting it quickly.

  According to the present invention, it is possible to obtain a stable image quality by reducing the temperature ripple as well as reducing the heat capacity and shortening the recovery time.

1 is a schematic sectional side view showing a configuration of an image forming apparatus using a fixing device according to an embodiment of the present invention. It is an enlarged side front view showing a main configuration of the fixing device same as above. It is a schematic diagram which shows transition of the pressurization temperature in the conventional structure which does not correct | amend the electric power supply to a heating source, (A) is a schematic diagram which shows temperature transition when pressurization temperature is low, (B) It is a schematic diagram which shows the temperature transition in case a pressure temperature is high. It is a schematic diagram which shows transition of the pressurization temperature in this apparatus which correct | amends the electric power supply to a heating source, (A) is a schematic diagram which shows temperature transition when pressurization temperature is low, (B) is pressurization It is a schematic diagram which shows the temperature transition in case temperature is high. It is a schematic sectional drawing which shows the schematic structure of the heating apparatus disclosed by patent document 3.

  Hereinafter, a fixing device according to the present invention and an image forming apparatus using the fixing device will be described with reference to the drawings. FIG. 1 is a side sectional view showing a schematic configuration of an image forming apparatus using a fixing device according to an embodiment of the present invention. In addition, in each figure, the same code | symbol is attached | subjected to the part which is the same or it corresponds, and those duplicate description is simplified or abbreviate | omitted suitably.

  Hereinafter, a color laser printer (hereinafter simply referred to as “printer”) will be described as an example of the image forming apparatus. The printer 10 shown in FIG. 1 is provided with four image forming units 11Y, 11M, 11C, and 11K in the central portion of the printer body. Each image forming unit 11Y and the like is the same except that it contains developers of different colors of yellow (Y), magenta (M), cyan (C), and black (BK) corresponding to the color separation components of the color image. It becomes the composition of.

  Each of the image forming units 11Y, 11M, 11C, and 11K includes a drum-shaped photoconductor 12, a charging device 13 that charges the surface of the photoconductor 12, a developing device 14, a cleaning device 15, and the like. The developing device 14 supplies toner to the surface of the photoconductor 12, and the cleaning device 15 cleans the surface of the photoconductor 12.

  In FIG. 1, only the photoconductor 12, the charging device 13, the developing device 14, and the cleaning device 15 included in the black image forming unit 11 </ b> K are denoted by reference numerals, and the other image forming units 11 </ b> Y, 11 </ b> M, 11C is omitted.

  Below the image forming units 11Y, 11M, 11C, and 11K, an exposure device 16 for exposing the surface of each photoconductor 12 is disposed. The exposure device 16 includes a light source, a polygon mirror, an f-θ lens, a reflection mirror, and the like, and irradiates the surface of each photoreceptor 12 with laser light based on image data.

  A transfer device 17 is disposed above the image forming units 11Y, 11M, 11C, and 11K. The transfer device 17 includes an intermediate transfer belt 18, four primary transfer rollers 19, a secondary transfer roller 20, a secondary transfer backup roller 21, a cleaning backup roller 22, a tension roller 23, and a belt cleaning device 24.

  The intermediate transfer belt 18 is formed in an endless shape and is stretched by a secondary transfer backup roller 21, a cleaning backup roller 22, and a tension roller 23. Here, the secondary transfer backup roller 21 is driven to rotate, so that the intermediate transfer belt 18 travels (rotates) in the direction indicated by the arrow in the figure.

  The four primary transfer rollers 19 sandwich the intermediate transfer belt 18 between the respective photoreceptors 12 to form primary transfer nips. Each primary transfer roller 19 is connected to a power source so that a predetermined DC voltage or AC voltage is applied.

  The secondary transfer roller 20 sandwiches the intermediate transfer belt 18 between the secondary transfer backup roller 21 and forms a secondary transfer nip. Similarly to the primary transfer roller 19, a power source is also connected to the secondary transfer roller 20, so that a predetermined DC voltage or AC voltage is applied.

  The belt cleaning device 24 includes a cleaning brush and a cleaning blade disposed so as to contact the intermediate transfer belt 18. The waste toner transfer hose extending from the belt cleaning device 24 is connected to the entrance of the waste toner container.

  A bottle container 25 is provided on the upper part of the printer main body, and four toner bottles 25Y, 25M, 25C, and 25K that contain toner for replenishment are detachably attached to the bottle container 25. .

  A replenishment path is provided between each of the toner bottles 25Y, 25M, 25C, and 25K and each of the developing devices 14. The toner is supplied to each developing device 14 from each of the toner bottles 25Y, 25M, 25C, and 25K through this supply path.

  On the other hand, at the lower part of the printer main body, a paper feed tray 26 containing paper P, a paper feed roller 27 for carrying out the paper P from the paper feed tray 26, and the like are provided. Here, the paper P includes thick paper, postcard, envelope, thin paper, coated paper (coated paper, art paper, etc.), tracing paper, OHP sheet and the like in addition to plain paper. A manual paper feed mechanism may be provided.

  In the printer main body, a transport path R is provided for discharging the paper P from the paper feed tray 26 through the secondary transfer nip and out of the printer main body. In the transport path R, a pair of registration rollers 28 for transporting the paper P to the secondary transfer nip is disposed upstream of the position of the secondary transfer roller 20 in the paper transport direction.

  Further, a fixing device A for fixing the unfixed image transferred to the paper P is disposed downstream of the position of the secondary transfer roller 20 in the paper transport direction. Further, a pair of paper discharge rollers 29 for discharging the paper P to the outside of the printer main body is provided downstream of the fixing device A in the paper transport direction of the transport path R. Further, on the upper surface of the printer main body, a paper discharge tray 9 for stocking the paper P discharged out of the printer main body by a pair of paper discharge rollers 29 is provided.

  Next, a fixing device A according to an embodiment of the present invention will be described with reference to the drawings. FIG. 2 is an enlarged front view showing the main configuration of the fixing device A according to the embodiment of the present invention. The fixing device A mainly includes a pressure roller 30 as a pressure member, a fixing belt 40 as a fixing member, a heating source 50, and a nip forming member 60.

  The fixing belt 40 is formed in an endless shape, and the heating source 50 and the nip forming member 60 described above are disposed therein. In this configuration, the fixing belt 40 is directly heated by the heating source 50 from the inner peripheral side. The fixing belt 40 uses a base 41 using a metal material such as nickel or SUS or a resin material such as polyimide. Further, the surface layer of the fixing belt 40 is coated with a release layer 42 such as PFA or PTFE, and has a release property so that toner does not adhere.

  There may be an elastic layer formed of a silicone rubber layer or the like between the base material 41 and the release layer 42 of the fixing belt 40. In addition, when there is no silicone rubber layer, the heat capacity is reduced and the fixability is improved. However, when the unfixed image is crushed and fixed, minute irregularities on the belt surface are transferred to the image and used in the solid portion of the image. There arises a problem that the skin-like gloss unevenness (zudder skin image) remains. In order to improve this, it is necessary to provide the silicone rubber layer with a thickness of 100 [μm] or more. Due to the deformation of the silicone rubber layer, fine irregularities are absorbed and the skin image can be improved.

  The heating source 50 shown in the present embodiment uses a halogen heater, but is not limited to this. For example, an IH, a resistance heating element, a carbon heater, or the like can be adopted. The nip forming member 60 is disposed so as to form a nip with the pressure roller 30 opposed via the fixing belt 40, and is in direct sliding contact with the inner peripheral surface of the fixing belt 40. . In addition, you may make it slide indirectly through a sliding sheet.

  The nip forming member 60 shown in the present embodiment shows a nip portion N formed on a flat surface, but may have a concave shape or other shapes. When the nip has a concave shape, the discharge direction of the leading edge of the paper P is closer to the pressure roller 30 and the separation is improved, so that the occurrence of jam can be suppressed.

  A support member (stay) 61 for supporting the nip portion N is provided inside the fixing belt 40 to prevent the nip forming member 60 that receives pressure from the pressure roller 30 from being bent and is uniform in the axial direction. Nip width can be obtained. The support member 61 is positioned by being held and fixed to a holding member (flange) 62 at both ends thereof. On the inner wall surface side of the support member 61, a reflection member 63 is disposed along the inner wall surface to block radiant heat from the heating source 50. Thereby, useless energy consumption due to the support member 61 being heated by radiant heat from the heating source 50 or the like is suppressed. Note that the same effect can be obtained by performing heat insulation or mirror treatment on the inner surface of the support member 61 instead of the reflecting member 63.

  The fixing belt 40 described above is rotated together with the pressure roller 30. That is, when the pressure roller 30 shown in FIG. 2 is rotated by the driving source, the driving force is transmitted to the fixing belt 40 in the nip portion N, and the driven roller rotates. Further, the fixing belt 40 rotates while being guided by the holding member 62 at both ends except for the nip portion N. With such a configuration, it is possible to realize a fixing device A that is inexpensive and has a fast warm-up.

  The pressure roller 30 is formed by forming an elastic rubber layer 32 on the outer peripheral portion of the cored bar 31, and a release layer (PFA or PTFE layer) is provided on the surface in order to obtain release properties. The pressure roller 30 is rotated by a driving force transmitted from a driving source such as a motor provided in the printer main body via a gear.

  The pressure roller 30 is pressed toward the fixing belt 40 by a spring or the like, and has a predetermined nip width by the elastic rubber layer 32 being crushed and deformed. The pressure roller 30 may have a hollow structure, or a configuration in which a heating source such as a halogen heater is provided inside the pressure roller 30 may be employed. The elastic rubber layer 32 may be solid rubber, but if no heat source is provided inside the pressure roller 30, sponge rubber may be used. Note that it is more preferable to use sponge rubber since heat insulation is enhanced and heat of the fixing belt 40 is hardly taken.

  Incidentally, the pressure roller 30 is provided with a pressure temperature detection sensor S1 for detecting the temperature of the pressure roller 30, and a power control circuit 70 is connected to the heating source 50 described above. The control unit 80 has a function of controlling the power supplied to the heating source 50 by executing a required program. A pressurization temperature detection sensor S1 is connected to the input side of the control unit 80, and a heating source 50 is connected to the output side. The control unit 80 shown in the present embodiment has the following functions.

  A function of correcting the power supply to the heating source 50 in accordance with the pressurization temperature detected by the pressurization temperature detection sensor S1 and correcting the expected power supply timing early. This function is referred to as “supply power correction means 80a”. Specifically, a fixed power determined according to a predetermined process condition is set, and the fixed power is increased or decreased according to the pressurization temperature obtained by the pressurization temperature detection sensor S1. “Predetermined process conditions” include the thickness, linear velocity, color mode, process linear velocity, and the like of the recording medium. “Fixed power” is determined according to a predetermined process condition, and is output in a fixed manner with respect to a paper passing mode required according to the predetermined process condition. 80 stored in the memory.

  The supplied power correction unit 80a performs increase / decrease correction based on the fixed power according to the pressurization temperature detected by the pressurization temperature detection sensor S1. Further, the power supply timing is corrected early according to the pressurization temperature detected by the pressurization temperature detection sensor S1 with respect to the intended power supply timing. The “predetermined power supply timing” is when the paper P enters the fixing nip. Specifically, the correction is made so that the supply power is increased as the pressurization temperature is increased and the supply power is reduced as the pressurization temperature is decreased. Further, from the predetermined power supply timing, the power supply timing is advanced as the pressurization temperature increases, and the supply power timing is delayed as the pressurization temperature decreases. Further, correction is performed when a predetermined time has not elapsed since the sheet P entered the fixing nip. That is, it is possible to determine an appropriate heat storage state of the fixing device A by detecting the temperature after the rotation is stabilized.

  FIG. 3 is a schematic diagram showing the transition of the pressurization temperature in the conventional configuration in which the power supply to the heating source is not corrected. FIG. 3A is a schematic diagram showing the transition of the temperature when the pressurization temperature is low. ) Is a schematic diagram showing a temperature transition when the pressurizing temperature is high. In the figure, the vertical axis represents temperature and the horizontal axis represents time.

  As shown in FIGS. 3 (A) and 3 (B), when the first sheet enters the place where the pressurization temperature is high toward the first sheet of paper P, the first sheet causes a drop. However, the temperature controllability deteriorates for a while under the influence. This problem is more likely to occur as a more prominent problem when the pressurization temperature is high in the conventional use mode. Further, for example, when the target temperature is low, such as when passing paper at a low speed, the influence is small, but the temperature controllability deteriorates due to the same cause.

  FIG. 4 is a schematic diagram showing the transition of the pressurization temperature in the present apparatus for correcting the power supply to the heating source, (A) is a schematic diagram showing the temperature transition when the pressurization temperature is low, (B) These are the schematic diagrams which show the temperature transition in case a pressurization temperature is high.

  As shown in FIGS. 4A and 4B, the fixed output is corrected according to the detection result of the pressurization temperature. In addition, the timing for outputting the fixed output is output earlier as the pressurization temperature is higher. Thereby, the target temperature controllability can be obtained.

  That is, for fixed output power, fixed power that is necessarily required in the sheet passing mode may be determined in advance according to the above-described predetermined process conditions such as the process linear velocity, the color mode, and the paper thickness of the paper P. It becomes necessary, and the increase / decrease correction of the supplied power is performed based on the fixed power. The predetermined power supply timing is preferably defined based on the timing at which the leading edge of the paper P enters the nip. However, if the correction timing is set too early, it leads to deterioration of controllability due to a temperature ripple that is overheated before the sheet is passed. Therefore, it is desirable to perform an evaluation in advance and use an optimum value for each image forming apparatus or fixing device. .

  As described above, since the temperature drop of the first sheet occurs remarkably when the sheet is fed from a state where the pressurization temperature is high, it is necessary to prevent the offset due to the drop of the first sheet. Therefore, the requested lighting duty is corrected according to the pressurizing temperature. Thereby, the user can obtain stable image quality in various usage situations while preventing the temperature drop and offset of the first sheet, reducing the heat capacity and shortening the recovery time.

10 Image forming device (printer)
11Y to 11K Image forming units 12 Each photoconductor 13 Charging device 14 Each developing device 15 Cleaning device 18 Intermediate transfer belt 19 Primary transfer roller 21 Secondary transfer backup roller 24 Belt cleaning device 25 Bottle storage unit 25Y to 25K Toner bottle 28 Resist Roller 29 Paper discharge roller 30 Pressure roller 31 Core metal 40 Fixing belt 41 Base material 50 Heating source 60 Nip forming member 61 Support member 62 Holding member 63 Reflecting member 80 Control unit 80a Supply power correction means P Recording medium (paper)
R Transport path S1 Pressure sensor

JP 2004-286922 A JP-A-4-44032 JP 2007-334205 A

Claims (8)

A fixing member for fixing unfixed toner to the recording medium;
A heating source for heating the fixing member;
A pressure member that pressurizes the recording medium with the fixing member;
A nip forming member that forms a nip with the pressure member;
A power control circuit for controlling power supplied to the heating source;
In a fixing device having a pressure temperature detection sensor for detecting the temperature of the pressure member,
According to the pressurization temperature detected by the pressurization temperature detection sensor, the power supply to the heating source is corrected to increase / decrease, and the power supply correction means for correcting the expected power supply timing early is provided. A fixing device. Fixed power that is determined according to predetermined process conditions is set,
The fixing device according to claim 1, wherein the supply power correction unit performs increase / decrease correction based on the fixed power in accordance with the pressurizing temperature.   The fixing device according to claim 1, wherein the supply power correction unit corrects the power supply timing early with respect to the expected power supply timing in accordance with the pressurizing temperature.   4. The supply power correction unit corrects the supply power to increase as the pressurization temperature increases and to decrease the supply power as the pressurization temperature decreases. The fixing device according to any one of the above.   5. The fixing device according to claim 3, wherein, from a predetermined power supply timing, the power supply timing is advanced as the pressurization temperature increases, and the supply power timing is delayed as the pressurization temperature decreases. . The predetermined power supply timing is when the recording medium enters the fixing nip,
The fixing device according to claim 5, wherein the supply power correction unit performs correction when a predetermined time has not elapsed since the recording medium entered the fixing nip.   The fixing device according to claim 2, wherein the predetermined process condition includes a thickness of a recording medium, a linear velocity, and a color mode.   An image forming apparatus using the fixing device according to claim 1.

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