JP2005250104A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus efficiently preventing dew condensation in the image forming apparatus with least power consumption. <P>SOLUTION: Regarding the image forming apparatus having a simultaneous secondary-transfer/fixing means 9 for thermally transferring/fixing a toner image on an intermediate transfer body 6 to a transfer material P en bloc by a heating means 91 arranged in contact with the intermediate transfer body 6 after the toner image formed on the image carrier 1 is transferred onto the intermediate transfer body 6, the image forming apparatus is provided with an in-machine temperature detecting means 11 for detecting the temperature inside the image forming apparatus, and the heating means 91 for the means 9 is controlled in accordance with the detection temperature by the in-machine temperature detecting means. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an in-machine dew condensation prevention measure in an image forming apparatus such as an electrophotographic system or an electrostatic recording system, for example, an image forming apparatus such as a copying machine or a laser beam printer.

  In the conventional image forming apparatus, there is a problem that image forming process equipment in the apparatus main body, for example, a photoconductor, a charging roller, a developing sleeve, a transfer roller, an optical lens, dust-proof glass, and the like are condensed to cause image defects. Such a phenomenon occurs when a night-cooled photosensitive drum or the like comes into contact with outside air heated by a heating device or the like, and is likely to occur immediately after starting up the apparatus, particularly in a cold region in winter.

  Furthermore, once dew condensation occurs, it usually takes about 1 to 2 hours to recover when the image forming apparatus is left in its natural state after power is turned on. Time is a problem and measures need to be taken.

Therefore, conventionally, as disclosed in Patent Document 1, for example, when the temperature inside the image forming apparatus becomes a certain temperature or less, temperature control of the fixing device is started to warm the inside of the apparatus for the purpose of preventing condensation. That has been done.
Japanese Patent Laid-Open No. 11-38861

  However, in the method of controlling the temperature of the fixing device as in the conventional method, in order to prevent condensation of the optical lens and dust-proof glass, which are often arranged relatively far from the fixing device as a heat source. However, it is necessary to set the temperature control temperature high or to energize the heater for a long time, resulting in a problem that power consumption increases. In addition, a fan and a duct for sending the wind are required, which hinders downsizing of the apparatus.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus that can efficiently prevent condensation in the image forming apparatus with as little power consumption as possible.

  In order to achieve the above object, the present invention according to claim 1 is to transfer a toner image formed on an image carrier onto an intermediate transfer member, and then transfer the toner image on the intermediate transfer member to the intermediate transfer member. In an image forming apparatus having a secondary transfer and simultaneous transfer unit that thermally transfers and fixes from an intermediate transfer member to a transfer material in a batch by a heating unit disposed in contact with the image forming apparatus, and detects the temperature in the image forming apparatus A temperature detection unit is provided, and the heating unit is controlled according to the temperature detected by the in-machine temperature detection unit.

  The present invention according to claim 2 is characterized in that the heating means is controlled in accordance with a detected temperature of the in-machine temperature detecting means in a power saving mode such as a sleep mode.

  The present invention according to claim 3 is characterized in that the rotation of the intermediate transfer member is controlled in accordance with the temperature detected by the in-machine temperature detecting means.

  According to a fourth aspect of the present invention, there is provided an outside temperature detecting means for detecting a temperature outside the image forming apparatus separately from the inside temperature detecting means, and the temperature detected by the inside temperature detecting means and the outside temperature detecting means Accordingly, the heating means is controlled.

  The present invention according to claim 5 is an in-machine temperature / humidity detection means in which the in-machine temperature detection means can also detect humidity.

  According to a sixth aspect of the present invention, there is provided an outside temperature / humidity detecting means for detecting a temperature / humidity outside the image forming apparatus separately from the inside temperature / humidity detecting means, and the inside temperature / humidity detecting means and the outside temperature / humidity detecting means. The heating means is controlled according to the detected temperature and humidity of the means.

  The present invention according to claim 7 is characterized in that the base material of the intermediate transfer member is made of metal.

  When the image forming apparatus is in sleep mode, etc., the temperature inside the machine detects the temperature inside the machine, and if the temperature inside the machine falls to a temperature where condensation is likely to occur, the temperature of the heating means of the secondary transfer simultaneous transfer means is adjusted to a predetermined temperature. By doing so, the internal temperature is raised to a temperature at which condensation is unlikely to occur due to the heat of the heating means, thereby preventing condensation. In this case, it is possible to efficiently raise the temperature inside each part by utilizing the heat conduction of the intermediate transfer member in contact with the heating means, and the temperature adjustment time (heater lighting time) of the heating means is short. In other words, it is possible to efficiently prevent condensation in the image forming apparatus with less power consumption.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(1) Schematic Configuration of Example of Image Forming Apparatus FIG. 1 is a longitudinal sectional view showing a schematic configuration of an example of an image forming apparatus according to the present invention. The image forming apparatus shown in FIG. 1 is a four-color full-color image forming apparatus in which four image forming units are arranged in tandem along the moving direction of an intermediate transfer belt as an intermediate transfer member. The image is transferred and fixed at the secondary transfer portion at the same time.

The image forming apparatus 100 includes first to fourth image forming units UK, UY, UM, and UC arranged in order from right to left in the drawing. These image forming units basically consist of the same electrophotographic image forming process mechanism,
a: a drum-type electrophotographic photosensitive member (hereinafter referred to as a photosensitive drum) 1 as a first image carrier, which is rotationally driven in a clockwise direction indicated by an arrow by a driving means (not shown);
b: a primary charger 2 that uniformly charges the surface of the photosensitive drum 1 to a predetermined polarity and potential;
c: exposure means 3, such as a laser scanner or LED array, for forming an electrostatic latent image by performing light image exposure L on the uniformly charged surface of the photosensitive drum 1;
d: a dust-proof glass 4 for preventing the exposure means 3 from being stained with toner or the like;
e: a developing device 5 for developing the electrostatic latent image formed on the photosensitive drum 1 as a toner image;
f: a primary transfer roller 7 as a first transfer means for transferring the toner image to an intermediate transfer body 6 as a second image carrier at a primary transfer nip T1;
f: a cleaner 8 for cleaning the surface of the photosensitive drum 1 after the transfer of the toner image to the intermediate transfer member 6;
And other electrophotographic image forming process equipment.

  The photosensitive drum 1 is obtained by providing OPC (organic optical semiconductor) as a photosensitive layer on the surface of an aluminum drum-shaped substrate. For example, a corona discharger can be used as the primary charger 2.

  The first image forming unit UK stores black toner as a developer in the developing device 5 and forms a black toner image on the photosensitive drum 1. The second image forming unit UY stores yellow toner as a developer in the developing device 5 and forms a yellow toner image on the photosensitive drum 1. The third image forming unit UM stores magenta toner as a developer in the developing device 5 and forms a magenta toner image on the photosensitive drum 1. The fourth image forming unit UC stores cyan toner as a developer in the developing unit 5 and forms a cyan toner image on the photosensitive drum 1.

  Note that the principle and process of forming a toner image by the electrophotographic image forming process mechanism as described above are well known, and the description thereof is omitted.

  In this embodiment, the intermediate transfer member 6 is an endless belt-like member (hereinafter referred to as an intermediate transfer belt), and forms each image below the first to fourth image forming units UK, UY, UM, and UC. An ascending belt portion is passed over the lower surface of the photosensitive drum 1 of the unit, and a driving roller 61, a tension roller 62, a fixing roller 91 as a heating unit of the secondary transfer simultaneous fixing device 9 described later, a belt guide member 63, an auxiliary The suspension is stretched between the five suspension members of the roller 64. The tension roller 62 applies a constant tension to the intermediate transfer belt 6. The intermediate transfer belt 6 is driven to rotate in the counterclockwise direction indicated by an arrow R6 at a substantially same peripheral speed as that of the photosensitive drum 1 as the driving roller 61 is driven to rotate.

  The primary transfer roller 7 in each of the first to fourth image forming units UK, UY, UM, and UC is disposed on the back side (inner surface side) of the intermediate transfer belt 6, and the upstream side belt portion (drive roller 61) of the intermediate transfer belt. A primary transfer nip portion T1 is formed between the photosensitive drum 1 and the front side (outer surface side) of the intermediate transfer belt 6 by pressing against the lower surface of the corresponding photosensitive drum 1 via a belt portion between the photosensitive drum 1 and the tension roller 62. I am letting.

  A pressure roller 92 is in pressure contact with the fixing roller 91 via the intermediate transfer belt 6 to form a secondary transfer nip T2 between the surface of the intermediate transfer belt. The fixing roller 91 and the pressure roller 92 are a secondary transfer simultaneous fixing device as a second transfer unit.

  Reference numeral 10 denotes an intermediate transfer belt cleaner, which is disposed in contact with the surface of the intermediate transfer belt 6 at the intermediate transfer belt winding portion of the auxiliary roller 64.

  Reference numeral 11 denotes an in-machine temperature detecting means for detecting the temperature in the image forming apparatus 100, which is disposed in the vicinity of the photosensitive drum 1 of the first image forming unit UK that is farthest from the secondary transfer simultaneous fixing apparatus 9. .

  The full color image forming operation is as follows. The first to fourth image forming units UK, UY, UM, and UC are sequentially driven in accordance with the timing of image formation. The intermediate transfer belt 6 is also driven to rotate. The black component toner image of the full color image is formed on the surface of the photosensitive drum 1 of the first image forming unit UK, and the yellow component toner image of the full color image is formed on the surface of the photosensitive drum 1 of the second image forming unit UY. A magenta component toner image of a full color image is formed on the surface of the photosensitive drum 1 of the third image forming unit UM, and a cyan component toner image of the full color image is formed on the surface of the photosensitive drum 1 of the fourth image forming unit UC. Each is formed at a predetermined control timing.

  The black toner image, the yellow toner image, the magenta toner image, and the cyan toner image formed on the surface of the photosensitive drum 1 of each image forming unit are applied to the surface of the intermediate transfer belt 6 in the primary transfer nip portion T1 of each image forming unit. Then, the images are sequentially superimposed and transferred in the aligned state, and an unfixed full-color toner image is synthesized and formed on the intermediate transfer belt 6.

  In this embodiment, the charging polarity of the photosensitive drum 1 is negative, and the toner used is a negative toner whose normal charging polarity is negative. The primary transfer roller 7 is supplied with a normally charged toner from a bias application power source (not shown). By applying a positive transfer bias having a polarity opposite to the charging polarity, a toner image is transferred from the photosensitive drum 1 side of the image forming unit to the intermediate transfer belt 6 side by the electric field of the primary transfer roller 7 in each primary transfer nip T1. Electrostatic transfer.

  The unfixed full-color toner image synthesized and formed on the intermediate transfer belt 6 is conveyed by the subsequent rotation of the intermediate transfer belt 6 to reach the secondary transfer nip T2, and a paper feeding mechanism is provided to the secondary transfer nip T2. The image is transferred by a fixing roller 91 and a pressure roller 92 of the secondary transfer simultaneous fixing device 9 to a transfer material P such as paper to be image-formed, which is fed from a section (not shown) at a predetermined control timing. The material is secondarily transferred to the surface of the material P and simultaneously heated and pressed (heated and melted and mixed). As a secondary transfer accelerating means, a secondary transfer bias having a polarity opposite to the charging polarity of the toner can be applied to the pressure roller 92 from a high voltage output circuit (not shown).

  The transfer material P that has undergone simultaneous transfer and fixing at the secondary transfer nip T2 is separated from the surface of the intermediate transfer belt 6 by the belt deflection unit formed by the belt guide member 63, and is discharged. The surface of the intermediate transfer belt 6 after separation of the transfer material is cleaned by the cleaner 10 and repeatedly used for image formation.

  In the case of forming a single color or 2-3 color toner image, the image forming unit of each selected color is operated to form the toner image on the intermediate transfer belt 6.

(2) Intermediate transfer belt 6
FIG. 2 is a schematic cross-sectional view showing the layer structure of the intermediate transfer belt 6 used in the image forming apparatus of this embodiment.

  Reference numeral 61 denotes a film base layer (base film) formed of a heat-resistant resin. Examples of the heat resistant resin include polyester, PET (polyethylene terephthalate), PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer), PTFE (polytetrafluoroethylene), polyphenylene sulfide, polyamideimide, polyimide, and polyether ether. High heat-resistant resins such as ketone and liquid crystal polymer, metal sheets such as aluminum and nickel, or composite materials such as ceramics, metal, and glass can be used.

  62 is a high release layer (surface layer) having a heat resistance of, for example, 5 μm. For example, the same fluororesin as PET, PFA, PTFE, etc., fluororubber, silicone resin, and silicone rubber similar to the above-described base layer 61 are used. It is done.

Furthermore, a more preferable configuration of the intermediate transfer belt 6 is to make the volume resistivity Rv as a whole 10 ⁵ to 10 ¹⁵ Ω · cm. The thermal conductivity is preferably 0.1 (W / mK) or more.

  In this embodiment, the intermediate transfer belt 6 uses a 50 μm-thick polyimide film as its base layer (base film) 61, and has a 5 μm-thick PFA whose resistance is reduced by carbon dispersion as a high release layer 62 on its surface. Layers were applied and configured. The perimeter is 80 cm.

(3) Secondary transfer simultaneous fixing device 9
FIG. 3 is an enlarged model view of the secondary transfer simultaneous fixing device 9 portion. In the fixing roller 91 and the pressure roller 92, respectively, cylindrical metal bases 91a and 92a are coated with elastic layers 91b and 92b and release layers 91c and 92c as necessary. As the metal substrates 91a and 92a, SUS, iron, Al, or the like can be used. For the elastic layers 91b and 92b, silicone rubber, fluorine rubber, or the like is used. As the release layers 91c and 92c, a fluororesin such as PET, PFA, PTFE or the like is used.

  The thermal conductivity of the elastic layers 91b and 92b is preferably in the range of λ = 0.3 to 0.8 (W / mK) from the viewpoint of fixability and the like. When λ <0.3, heat is slowly transferred to the roller surface, and heater control becomes difficult. In addition, rubber with λ> 0.8 generally has low thermal durability, and peeling from the core bars 91a and 92a is likely to occur. The fixing roller 91 and the pressure roller 92 include heaters (heat sources) 93 and 94, respectively. As the heaters 93 and 94, a halogen lamp, a nichrome wire heater, or the like is used.

  In this embodiment, the fixing roller 91 includes a metal core 91a having a thickness of 1.6 mm and an outer diameter of 48.5 mm, a silicone rubber 2.3 mm as the elastic layer 91b, and a PFA tube as the release layer 91c. It is made by coating 50 μm. The thermal conductivity of the silicone rubber was 0.5 (W / mK). Similarly, the pressure roller 92 covers a metal core 92a having a thickness of 2.0 mm and an outer diameter of 38 mm with a core metal of 2.1 mm as an elastic layer 92b and a PFA tube of 50 μm as a release layer 92c. It is made. The thermal conductivity of the silicone rubber is λ = 0.5 (W / mK) similarly to the fixing roller 91. The heater 93 of the fixing roller 91 is a 700 W halogen lamp, and the heater 94 of the pressure roller 92 is a 300 W halogen lamp.

  Reference numerals 95 and 96 denote contact-type or non-contact-type surface temperature detection means for detecting the surface temperatures of the fixing roller 91 and the pressure roller 92, respectively. Temperature measurement information of each surface temperature detection means 95 and 96 is input to a temperature control circuit unit (not shown). The temperature control circuit unit controls the power supplied to the heaters 93 and 94 so that the temperature measurement information input from the surface temperature detection means 95 and 96 is maintained at a predetermined control temperature. The surface temperature of 92 is adjusted to a predetermined control temperature.

(4) In-machine dew prevention measures Generally, in an image forming apparatus, the “power saving mode” is a function for controlling the power of the image forming apparatus. "Low-power mode" with reduced power consumption to a level that can return to the normal mode, and "Sleep" with reduced power consumption at a level that can receive information but does not matter the return time to normal mode Mode "and" off mode "which basically turns off the power of the image forming apparatus. In the sleep mode, the heater of the fixing device that consumes a relatively large amount of power is often not energized.

  Here, a case where the apparatus is started up in the morning after being left in the sleep mode for a long time in the sleep mode, in which condensation is generally likely to occur will be considered. In the sleep mode, when the temperature detection means 11 detects less than 10 ° C., the heater part of the secondary transfer simultaneous fixing device 9 is energized, and when 15 ° C. or more is detected, the energization is turned off. Here, 10 ° C. is an example, and 5 ° C., 10 ° C., 15 ° C., etc., 5 ° C. increments, 3 ° C. increments, or the like may be selected according to the installation environment of the image forming apparatus. . The installation environment here refers to humidity, heating usage, etc. in addition to temperature.

  FIG. 4 is a block diagram of an energization control system for the heater 93, which is an internal heat source of the fixing roller 91 as a heating unit, provided in the secondary transfer simultaneous fixing device 9 in this embodiment. Reference numeral 101 denotes a power supply unit, 102 denotes an energization control circuit unit, 103 denotes a first temperature control circuit unit (CPU), and 104 denotes a second temperature control circuit unit (CPU). When the temperature inside the image forming apparatus is detected by the in-machine temperature detection means 11 and the temperature measurement information is fed back to the first temperature control circuit unit 103 and the temperature of the secondary transfer simultaneous fixing unit is required, A temperature control start signal is sent to the second temperature control circuit unit 104. The second temperature control circuit unit 104 to which the temperature adjustment start signal is sent controls the energization control circuit 102 according to the temperature detected by the surface temperature detecting means 95 and controls the energization from the power source 101 to the heater 93.

  In this embodiment, as shown in the flowchart of temperature control in FIG. 5, the temperature of the fixing roller 91 of the secondary transfer simultaneous fixing device 9 is adjusted to 150.degree. When 11 detects less than 10 ° C., the heater 93 is energized, and when 15 ° C. or more is detected, if the heater 93 is de-energized, condensation may not occur in the machine even when the apparatus is started up in the morning. confirmed. The average power consumption consumed by the fixing device at this time was 70 (Wh / h).

  FIG. 6 shows the relationship between the detected temperature and time of the actual in-machine temperature detecting means 11 and the fixing roller temperature and time. Hereinafter, FIG. 6 will be described. Here, the low power mode is a mode in which the temperature of the fixing roller 91 of the secondary transfer simultaneous fixing device 9 is adjusted to 175 ° C., and the sleep mode is basically the temperature of the secondary transfer simultaneous fixing device 9. The temperature is adjusted to 150 ° C. only when the temperature detected by the in-machine temperature detection means 11 is less than 10 ° C. in a cold district or the like. On the horizontal axis, the time taken to shift from the low power mode to the sleep mode is 0 minute. In the vertical axis, graph 1 represents the temperature detected by the in-machine temperature detection means 11, and graph 2 represents the temperature of the fixing roller 91 of the secondary transfer simultaneous fixing device 9. Thereafter, as can be seen from graph 1 after about 80 minutes, since the temperature detected by the in-machine temperature detecting means 11 is less than 10 ° C., the temperature control of the fixing roller 91 of the secondary transfer simultaneous fixing device 9 starts. The range in which graph 1 is increasing to the right from 10 ° C. to 15 ° C. is the time zone during which the fixing roller 91 is temperature-controlled to 150 ° C. (“temperature adjustment region” in FIG. 6). It turns out that it vibrates around 150 degreeC. In more detail, in graph 2, the portion of the temperature adjustment region that rises to the right is the time zone in which the heater 93 is lit, and the portion that falls to the right is the time zone in which the heater 93 is lit off. On the other hand, a portion where the graph 1 is lowered to the right from 15 ° C. to 10 ° C. is a region where the temperature of the fixing roller 91 is not controlled.

  As a comparative experiment, an image forming apparatus in which the secondary transfer nip portion T2 and the fixing device 9A shown in FIG. 65 is a secondary transfer portion facing roller, and 66 is a secondary transfer roller. The secondary transfer of the toner image from the secondary transfer belt 6 side to the transfer material P side in the secondary transfer nip T2 is performed by applying a secondary transfer bias to the secondary transfer roller 66. 1 is the same as the image forming apparatus shown in FIG. 1 except that the secondary transfer nip T2 and the fixing device 9A are separated.

  The fixing roller 91 and the pressure roller 91 of the fixing device 9A in the image forming apparatus of FIG. 7 used for the comparative experiment have the same structure as the fixing roller 91 and the pressure roller 92 of the image forming apparatus of FIG. In the apparatus shown in FIG. 7 as well, when the temperature detected by the in-machine temperature detecting means 11 is less than 10 ° C., the heater 93 of the fixing roller 91 of the fixing device 9A is energized and the temperature is adjusted at 150 ° C. When the temperature detected by the in-machine temperature detecting means 11 is 15 ° C. or higher, the heater 93 is not energized. In this case as well, it was confirmed that condensation would not occur in the aircraft when the device was started up in the morning. On the other hand, the average power consumption consumed by the fixing device 9A at this time was 90 (Wh / h).

  FIG. 8 shows the relationship between the detected temperature and time of the in-machine temperature detecting means 11 of the image forming apparatus and the fixing roller temperature and time in this comparative experiment. Compared with FIG. 6, the “temperature control region” is longer, and it can be seen that the average power consumption is higher in the comparative experiment.

  Accordingly, the average power consumption for preventing dew condensation in the same way is that the image forming apparatus having the former transfer and simultaneous fixing unit is compared with the latter image forming apparatus in which the secondary transfer unit and the fixing device are separated. You can see that it is small.

  The difference between the average power consumption of the former and the latter is that the former has a larger heat capacity because the intermediate transfer belt 6 also has to be warmed, but the secondary transfer simultaneous fixing device 9 uses the heat conduction of the belt 6. It is possible to warm the vicinity of the dust-proof glass 4 of the first image forming unit UK far from the heater, and as a result, the heater lighting time is shorter than the latter.

Actually, the thermal conductivity of the intermediate transfer belt 6 used in this embodiment is 0.6 (W / mK), while the thermal conductivity of air is 2.41 × 10 ⁻² (W / mk). is there. Therefore, as in the image forming apparatus of FIG. 7, the image of the fixing device 9A is heated via the intermediate transfer belt 6 as in the image forming apparatus of the present embodiment. It is more efficient to warm the entire forming apparatus.

  In the present embodiment, the case where the base layer of the intermediate transfer belt 6 is polyimide has been described. However, when a metal such as aluminum is used as the base layer, it is expected that the heat transfer efficiency of the intermediate transfer belt 6 is further increased. it can. Actually, the thermal conductivity of aluminum is 236 (W / mK), and the thermal conductivity of nickel is 94 (W / mK).

  Further, in this embodiment, an example is shown in which only the fixing roller 91 of the secondary transfer simultaneous fixing device 9 is temperature-controlled in the sleep mode, but the pressure roller 92 may be temperature-controlled at the same time.

  The image forming apparatus in this embodiment is the same as that shown in FIG. In this embodiment, the intermediate transfer belt 6 is rotated at regular intervals in the sleep mode. By rotating the intermediate transfer belt 6 during the sleep mode, the entire intermediate transfer belt 6 can be warmed, and the entire apparatus can be warmed, and the effect of preventing dew condensation is further enhanced.

  FIG. 9 is a block diagram of an energization control system for the heater 93 inside the fixing roller 91 and a drive control system for the intermediate transfer belt 6 provided in the simultaneous transfer fixing device 9 in this embodiment. An intermediate transfer belt rotation control unit 105 is added to FIG. The operation of other parts is the same as in the case of FIG. When the temperature inside the image forming apparatus is detected by the in-machine temperature detecting means 11 and the temperature detection information is fed back to the first temperature control circuit unit 103 and the temperature adjustment of the simultaneous transfer fixing unit is required, the intermediate transfer is performed. A drive control start signal is sent to the belt drive control unit 105. The intermediate transfer belt drive control unit 105 to which the drive control start signal is sent rotates the intermediate transfer belt 6 intermittently or continuously.

  Actually, in the sleep mode of the image forming apparatus, when the in-machine temperature detecting means 11 detects less than 10 ° C., the secondary transfer simultaneous fixing device 9 is adjusted to 150 ° C., and the in-machine temperature detecting means 11 is 15 ° C. When the above was detected, it was confirmed that when the heater 93 was deenergized and temperature-controlled, no condensation occurred in the machine even when the apparatus was started up in the morning. At this time, the intermediate transfer belt 6 was continuously rotated in the “temperature adjustment region” as shown in the graph of FIG. The average power consumption consumed by the secondary transfer simultaneous fixing device 9 at this time was 60 (Wh / h). As described in the comparative experiment of Example 1, in the case of the machine in FIG. 7 where the secondary transfer portion T2 and the fixing portion 9A are separated, if condensation is prevented by the same method, 90 (Wh / h) Since it becomes average power consumption, it turns out that it is advantageous also in terms of energy.

  In this embodiment, an example in which the intermediate transfer belt 6 rotates continuously has been described. However, as shown in FIG. 11, the intermediate transfer belt 6 may be rotated intermittently such that it rotates for 1 minute and stops for 2 minutes. Further, the rotation and stop time can be determined as appropriate for each image forming apparatus.

  An image forming apparatus in this embodiment is shown in FIG. An outside temperature detector 12 for measuring the temperature outside the image forming apparatus is provided. Other portions are the same as those in FIG. 1 which is the image forming apparatus in the first embodiment. Condensation in the image forming apparatus occurs when air outside the apparatus having a high temperature contacts parts in the apparatus having a low temperature. Accordingly, by measuring both the temperature in the image forming apparatus and the temperature of the outside air, it is determined whether to energize the heater 93 of the fixing roller 91 of the secondary transfer simultaneous fixing apparatus 9 in the sleep mode based on the temperature difference. As compared with the case where the energization time to the heater 93 is controlled only by the temperature inside the apparatus, useless lighting of the heater 93 can be suppressed and the power consumption can be further reduced.

  FIG. 13 shows the relationship between the detected temperature difference and time of the actual temperature detecting means, and the fixing roller temperature and time. Here, the detected temperature difference is a temperature calculated as (temperature in the apparatus) − (temperature outside the apparatus). In this embodiment, when the temperature outside the apparatus is 5 ° C. or more higher than the temperature inside the apparatus, the temperature of the fixing roller is adjusted to 150 ° C. When the temperature difference between the inside and outside of the apparatus becomes 0 ° C., the temperature adjustment is performed. An example of quitting is shown below.

  In this case, although depending on the environment outside the apparatus, it is possible to reduce the average consumption output as compared with the case where the control is performed only by the temperature inside the apparatus.

  Furthermore, in addition to the temperature, it is also possible to control the energization of the heater 93 by measuring the humidity inside and outside the apparatus. For example, the in-machine temperature detecting means 11 is used as an in-machine temperature / humidity detecting means capable of detecting the in-machine humidity. The outside temperature detecting means 12 for detecting the temperature outside the image forming apparatus also detects the outside humidity. It is also possible to use the external temperature / humidity detection means, and the secondary transfer according to the detected temperature and humidity of the internal temperature / humidity detection means 11 or the internal temperature / humidity detection means 11 and the external temperature / humidity detection means 12. It is also possible to control the energization of the heater 93 of the fixing roller 91 of the simultaneous fixing device 9.

  Specifically, it is performed as follows. FIG. 14 is an example of a table for obtaining the absolute moisture content in the air from the temperature and humidity of the air. Such a table can be easily obtained from saturated water vapor pressure data at each temperature. The absolute moisture content in the air outside the apparatus is obtained from the temperature and humidity of the air outside the apparatus, and the absolute moisture content in the air inside the apparatus is also obtained. It is also possible to make a table with more detailed division of temperature and humidity.

Where (absolute water content difference) =
(Absolute moisture content in the air outside the device) − (Absolute moisture content in the air inside the device)> 5 g / Kg DryAir
In this case, the temperature of the fixing roller is adjusted to 150 ° C., and (absolute water content difference) <2 g / Kg DryAir
In such a case, it is possible to control to turn off the temperature.

  The threshold value of the absolute moisture amount at the start of temperature adjustment here can be adjusted according to the structural ease of condensation of the apparatus or the difficulty of condensation.

[Others]
1) In the secondary transfer simultaneous fixing device 9, the fixing roller 91 as a heating unit disposed in contact with the inner surface of the intermediate transfer body 6 is a hot plate or the like in which the surface on which the inner surface of the intermediate transfer body contacts and slides is smoothed. The non-rotating member can also be used.

  2) The intermediate transfer member 6 as the second image carrier is not limited to the endless belt member, but may be a drum-like member.

  3) The image forming principle / process of the image forming apparatus is not limited to the electrophotographic process, and may be an electrostatic recording process, a magnetic recording process, or the like.

  4) The present invention is not limited to the full-color image forming apparatus of the embodiment, but can be applied to a mono-color image forming apparatus.

1 is a schematic configuration diagram of an image forming apparatus in Embodiment 1. FIG. FIG. 3 is a schematic configuration diagram of an intermediate transfer belt. FIG. 4 is an enlarged model view of a secondary transfer simultaneous fixing device portion. 3 is a block diagram of an energization control system for a heater of a fixing roller. FIG. 7 is a flowchart of heater control for a fixing roller in a sleep mode. 6 is a graph showing the relationship between the detected temperature and time of the in-machine temperature detecting means and the fixing roller temperature and time. 1 is a schematic configuration diagram of an image forming apparatus of a comparative example. 7 is a graph showing a relationship between a detected temperature and time of an in-machine temperature detecting unit and a fixing roller temperature and time in a comparative example. 6 is a block diagram of an intermediate belt / fixing roller control system in Embodiment 2. FIG. 6 is a graph showing a relationship between a temperature detected by a temperature detecting unit and time, and a fixing roller temperature and time in Example 2. 6 is a graph showing an intermittent rotation sequence of a secondary transfer simultaneous fixing unit in Example 2. 6 is a schematic configuration diagram of an image forming apparatus in Embodiment 3. FIG. 10 is a graph showing a relationship between a detected temperature difference and time of a temperature detecting unit and a fixing roller temperature and time in Example 3. It is a table showing the correspondence of the absolute water content with respect to temperature and humidity in the air.

Explanation of symbols

  UK, UY, UM, UC, ... 1st to 4th image forming units, 6 ... Intermediate transfer belt, 9 ... Secondary transfer simultaneous fixing device, 11 ... Machine temperature detection means

Claims (7)

After the toner image formed on the image carrier is transferred onto the intermediate transfer member, the toner image on the intermediate transfer member is thermally transferred to the intermediate transfer member by a heating means disposed in contact with the intermediate transfer member. In an image forming apparatus having a secondary transfer and simultaneous fixing means for collectively transferring and fixing to a transfer material from
An image forming apparatus comprising an in-machine temperature detecting means for detecting a temperature in the image forming apparatus, and controlling the heating means in accordance with a temperature detected by the in-machine temperature detecting means.   The image forming apparatus according to claim 1, wherein the heating unit is controlled according to a temperature detected by the in-machine temperature detection unit during a power saving mode such as a sleep mode.   The image forming apparatus according to claim 1, wherein the rotation of the intermediate transfer member is controlled in accordance with a temperature detected by the in-machine temperature detecting unit.   In addition to the in-machine temperature detecting means, an in-machine temperature detecting means for detecting the temperature outside the image forming apparatus is provided, and the heating means is controlled according to the detected temperatures of the in-machine temperature detecting means and the outside temperature detecting means. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.   5. The image forming apparatus according to claim 1, wherein the in-machine temperature detecting unit is an in-machine temperature / humidity detecting unit capable of detecting humidity.   In addition to the in-machine temperature / humidity detection means, an in-machine temperature / humidity detection means for detecting temperature / humidity outside the image forming apparatus is provided. The image forming apparatus according to claim 5, wherein the heating unit is controlled.   The image forming apparatus according to claim 1, wherein a base material of the intermediate transfer member is made of metal.