JP2006145968A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of preventing the lowering of accuracy in detecting the surface temperature of a thermal fixing member caused by the adhesion of a waterdrop to a non-contact temperature sensor. <P>SOLUTION: The image forming apparatus has the thermal fixing member to heat recording paper to which a toner image is transferred and fix the toner image on the recording paper, and the non-contact temperature sensor to detect the surface temperature of the thermal fixing member in a non-contact state, and has a temperature and humidity detecting means to detect temperature and humidity inside the image forming apparatus. When the temperature and humidity detecting means detects that the temperature and the humidity inside the image forming apparatus are the ones previously set as a range where dew condensation occurs on the surface of the non-contact temperature sensor, the traveling of the recording paper is inhibited. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus. In particular, in an electrophotographic image forming apparatus, it is effective that water droplets adhere to a non-contact temperature sensor and the accuracy of detecting the surface temperature of the heat fixing member is reduced. The present invention relates to an image forming apparatus that can be prevented.

  2. Description of the Related Art In electrophotographic image forming apparatuses such as copying machines and printers, a toner image is generally transferred onto a recording paper, and this is heated and melted to be thermally fixed. Thermal fixing members such as a thermal fixing roller are widely used for thermal fixing of toner images.

  In order to stably fix the toner image on the recording paper using the heat fixing member, it is necessary to detect the surface temperature of the heat fixing member with a temperature sensor and control the surface temperature to be within a predetermined temperature range.

  Here, if a contact type sensor is used as the temperature sensor, the surface of the heat fixing member may be damaged, thereby causing an image defect.

  Therefore, a non-contact temperature sensor such as an infrared temperature sensor is widely used for detecting the surface temperature of the heat fixing member so as not to damage the surface of the heat fixing member.

  However, when the amount of moisture contained in the recording paper is large, such as when the temperature is relatively low and the humidity is high, moisture evaporated from the recording paper may adhere to the optical surface of the non-contact temperature sensor and cause condensation. is there.

  If dew condensation occurs on the optical surface of the non-contact temperature sensor, the infrared rays emitted from the surface of the overheating fixing member are absorbed by the dew condensation, and the surface temperature of the heat fixing member cannot be measured accurately.

Therefore, it has been studied to prevent water droplets from adhering to the non-contact temperature sensor by covering the non-contact temperature sensor and the substrate on which the non-contact temperature sensor is mounted with a box-shaped housing (Patent Document 1). ). Further, since the water vapor is generated from the outlet side of the sandwiching portion formed by the pressure member that presses the recording paper against the heat fixing member and the heat fixing member, the non-contact temperature sensor is provided at the entrance of the sandwiching portion. (Patent Document 2)
JP 2002-340682 A JP-A-7-77891

However, even when the non-contact temperature sensor and the substrate are covered with a box-shaped housing, it is necessary to provide the housing with an opening through which infrared rays from the heat fixing member pass. When an opening is provided in the housing, there is a possibility that foreign matters such as water vapor, paper powder, and toner enter the housing after passing through the opening and adhere to the non-contact temperature sensor and the substrate. If the housing is to be installed at a position where no foreign matter enters from the opening, the installation location is limited and the entire image forming apparatus is increased in size. Also,
On the other hand, when a non-contact temperature sensor is provided at the entrance of the sandwiching section, there is a problem that a place where the non-contact temperature sensor can be installed is greatly limited.

  The present invention has been made to solve the above-described problem, and can effectively prevent a drop in the accuracy of detecting the surface temperature of the heat fixing member due to water droplets adhering to the non-contact temperature sensor. The purpose is to provide a device.

  According to the first aspect of the present invention, there is provided a heat fixing member that heats a recording sheet on which a toner image is transferred to fix the toner image on the recording sheet, and a non-contact detection that detects a surface temperature of the heat fixing member. An image forming apparatus having a contact temperature sensor, comprising temperature / humidity detection means for detecting temperature and humidity inside the image forming apparatus, wherein the inside of the image forming apparatus is preliminarily set as a range in which the surface of the non-contact temperature sensor is condensed. The present invention relates to an image forming apparatus characterized in that, when the temperature and humidity detection means detects that the temperature and humidity is set, the recording paper is prohibited from traveling.

  In the image forming apparatus, when the inside is at a temperature and humidity in a range where the surface of the non-contact temperature sensor is condensed, the recording paper is prohibited from running, so printing on the recording paper is also prohibited.

  Therefore, it is possible to prevent the occurrence of print defects due to the temperature detection surface of the non-contact sensor dewing and the surface temperature of the heat fixing member cannot be measured accurately.

  According to a second aspect of the present invention, there is provided a thermal fixing member that heats a recording sheet on which a toner image is transferred to fix the toner image on the recording sheet, and a non-contact detection that detects a surface temperature of the thermal fixing member. An image forming apparatus having a contact temperature sensor, comprising temperature / humidity detection means for detecting temperature and humidity inside the image forming apparatus, wherein the inside of the image forming apparatus is preliminarily set as a range in which the surface of the non-contact temperature sensor is condensed. The present invention relates to an image forming apparatus characterized in that when the temperature / humidity detecting means detects that the temperature / humidity is determined, the page interval of a recording sheet is made wider than the page interval during normal image formation.

  When the inside of the image forming apparatus is at a temperature and humidity such that the non-contact temperature sensor is condensed, naturally, the surroundings of the image forming apparatus are also in high humidity and relatively low temperature weather conditions. It is considered that the amount of water in the recording paper has increased.

  Therefore, if a large amount of recording paper is sent under such weather conditions before the heat fixing member is sufficiently heated, dew condensation occurs in the non-contact temperature sensor due to moisture evaporated by the recording paper coming into contact with the heat fixing member. there is a possibility.

  In the image forming apparatus, when the inside is at a temperature and humidity in a range where the surface of the non-contact temperature sensor is condensed, the page interval of the recording paper is wider than the page interval during normal image formation. Therefore, the amount of moisture evaporated from the recording paper per unit time can be reduced, and therefore, condensation of the non-contact temperature sensor can be prevented.

  According to a third aspect of the present invention, in the image forming apparatus according to the first aspect, a predetermined time that is predetermined as a time until the heat-fixing member is heated to a temperature at which condensation does not occur in the non-contact temperature sensor. It relates to the one that cancels the prohibition of running of the recording paper after the lapse.

  According to a fourth aspect of the present invention, in the image forming apparatus according to the second aspect of the present invention, a predetermined time as a time until the heat fixing member is heated to a temperature at which no condensation occurs in the non-contact temperature sensor. The present invention relates to the one that narrows the page interval of the recording paper to the page interval at the time of normal image formation after the lapse.

  In these image forming apparatuses, when the predetermined time elapses, the prohibition of running of the recording paper is automatically canceled, or the page interval of the recording paper is reduced to shift to the normal printing mode. However, there is no need to confirm that the heat-fixing member has been sufficiently heated and cancel the running of the recording paper or shift to the normal printing mode.

  According to a fifth aspect of the present invention, in the image forming apparatus according to the first aspect, the temperature and humidity inside the image forming apparatus is a predetermined range as the temperature and humidity at which the temperature detection surface of the non-contact temperature sensor condenses. When the temperature / humidity detection means detects that the recording paper has been removed, the recording paper is canceled.

  According to a sixth aspect of the present invention, in the image forming apparatus according to the second aspect, the temperature / humidity inside the image forming apparatus is predetermined as a temperature / humidity where the temperature detection surface of the non-contact temperature sensor is condensed. When the temperature / humidity detecting means detects that the image is out of the range, the page interval of the recording paper is reduced to the page interval during normal image formation.

  In these image forming apparatuses, since it is determined whether or not the prohibition of running of the recording paper should be canceled based on the temperature / humidity detection result in the temperature / humidity detecting means, the temperature / humidity inside the image forming apparatus is Even though the temperature / humidity is still in the range where condensation occurs in the non-contact temperature sensor, the prohibition of recording paper travel is canceled or the normal print mode is entered and the non-contact temperature sensor condenses. The situation can be avoided.

  A seventh aspect of the present invention is the image forming apparatus according to any one of the first to sixth aspects, further comprising a heat fixing member cooling means for cooling the heat fixing member, and the inside of the image forming apparatus. However, when the temperature / humidity detecting means detects that the temperature / humidity is predetermined as a range in which condensation occurs on the surface of the non-contact temperature sensor, cooling of the heat fixing member by the heat fixing member cooling means is stopped. About what to do.

  In the image forming apparatus, when the inside of the image forming apparatus is at a temperature and humidity in a range where the surface of the non-contact temperature sensor is condensed, the cooling of the heat fixing member is stopped. To be heated.

  Therefore, since the heat fixing member and its periphery are heated more rapidly, printing in the normal mode can be started in a shorter time.

  According to an eighth aspect of the present invention, in the image forming apparatus according to any one of the first to seventh aspects, the temperature inside the image forming apparatus is predetermined as a range in which the surface of the non-contact temperature sensor is condensed. When the temperature / humidity detecting means detects that the humidity is present, the present invention relates to an apparatus for increasing the heating rate of the heat fixing member.

  In the image forming apparatus, when the inside of the image forming apparatus is at a temperature and humidity in a range where the surface of the non-contact temperature sensor is condensed, the heating of the heat fixing member is positively accelerated. You can start printing in normal mode.

  According to a ninth aspect of the present invention, in the image forming apparatus according to any one of the first to eighth aspects, the non-contact temperature sensor detects that the surface temperature of the heat fixing member is higher than a predetermined value. When the inside of the image forming apparatus prints on the recording paper in the normal mode without determining whether or not the temperature / humidity is predetermined as a range in which the surface of the non-contact temperature sensor is condensed. About.

  In the image forming apparatus, as soon as a series of prints are completed, printing in the normal mode can be started immediately under the condition that sufficient heat remains on the heat fixing member and no condensation occurs on the non-contact temperature sensor. Therefore, there is little waste of time.

  As described above, according to the present invention, there is provided an image forming apparatus that can effectively prevent a drop in accuracy of detecting the surface temperature of a heat fixing member due to water droplets adhering to a non-contact temperature sensor.

1. Embodiment 1
A tandem full-color printer as an example of the image forming apparatus of the present invention will be described below.

  As shown in FIG. 1, a full-color printer 1000 according to the first embodiment includes a paper cassette 42 that stores recording paper S, and an image forming unit 12 that is disposed above the paper cassette 42 and forms a toner image. The transfer unit 14 transfers the toner image formed by the image forming unit 12 to the recording paper S conveyed from the paper cassette 42, and the fixing unit 16 fixes the toner image transferred to the recording paper S by the transfer unit. Prepare. A discharge tray 52 on which the recording paper S on which the toner image is fixed is stacked is disposed adjacent to the exit side of the fixing unit 16.

  A nip formed by a pickup roller 44 and a retard roller 46 provided in the vicinity of the paper discharge port of the paper cassette 42, a paper conveyance roller 48, a secondary intermediate transfer drum 38 and a transfer roller 40 described later. The conveyance path W of the recording sheet S from the sheet cassette 42 to the discharge tray 52 is formed by the section, the fixing section 16, and the discharge roller pair 50 provided on the exit side of the fixing section 16.

  In the image forming unit 12, image forming units 24Y, 24M, 24C, and 24K that form toner images of Y (yellow), M (magenta), C (cyan), and K (black) are provided at predetermined intervals. Are arranged in tandem in the vertical direction. Since the image forming units 24Y, 24M, 24C, and 24K have substantially the same configuration, the internal configuration will be described below taking the image forming unit 24Y as an example.

  The image forming unit 24Y includes a photosensitive drum 28 that is rotationally driven in the direction of arrow A, a charging roller 30 that contacts and uniformly charges the surface of the photosensitive drum 28, and a rotational direction A of the photosensitive drum 28. And a developing device 32 disposed on the downstream side of the charging roller 30.

  A laser irradiation unit 26 is disposed adjacent to the right side in FIG. 1 of the image forming unit 24Y, the image forming unit 24M, the image forming unit 24C, and the image forming unit 24K. The laser irradiation unit 26 irradiates four laser beams R (Y), laser beams R (M), laser beams R (C), and laser beams R (K). The laser beam R (Y) is applied to a portion between the charging roller 30 and the developing device 32 of the photosensitive drum 28 included in the image forming unit 24Y. Similarly, the laser beam R (M) is applied to a portion between the charging roller 30 and the developing device 32 of the photosensitive drum 28 included in the image forming unit 24M. Similarly, the laser beam R (C) and the laser beam R (K) are applied to a portion between the charging roller 30 and the developing device 32 of the photosensitive drum 28 included in the image forming unit 24C and the image forming unit 24K, respectively. The

  The transfer unit 14 includes a primary intermediate transfer drum 36A to which a toner image formed on the photosensitive drum 28 of the image forming unit 24Y and the image forming unit 24M is transferred, and the photosensitive drum 28 of the image forming unit 24C and the image forming unit 24K. A primary intermediate transfer drum 36B to which the toner image formed on the toner image is transferred, and a primary intermediate transfer drum 38A and a secondary intermediate transfer drum 38 to which the toner image transferred to the primary intermediate transfer drum 36B is transferred.

  As shown in FIGS. 1 and 2, the fixing unit 16 includes a heating roller 56 that heats the surface of the recording sheet S on which the toner image is transferred, and a pressure roller 58 that presses the recording sheet S against the heating roller 56. And a housing 54 that houses the heating roller 56 and the pressure roller 58. The heating roller 56 corresponds to a heat fixing member in the image forming apparatus of the present invention. A pair of transport rollers 69 is disposed on the downstream side in the transport direction of the heating roller 56 and the pressure roller 58 inside the housing 54. A temperature sensor unit 70 is installed diagonally above the housing 54 via an L-shaped plate 55. The temperature sensor unit 70 corresponds to a non-contact temperature sensor in the image forming apparatus, and is an infrared thermometer that detects the surface temperature of the heating roller 56. The temperature sensor unit 70 is provided so as to face the heating roller 56 through an opening 59 provided in the housing 54.

  The heating roller 56 has a cylindrical metal core 62, and the metal core 62 is covered with a heat resistant elastic layer 61. A release layer 60 such as a fluororesin or a silicone resin is provided on the surface of the heat resistant elastic layer 61.

  A halogen lamp 63 for heating the surface temperature of the heating roller 56 is installed inside the metal core 62. The heating roller 56 is rotationally driven clockwise (arrow X direction) by a driving source (not shown).

  On the other hand, the pressure roller 58 is in contact with the heating roller 56 and is driven to rotate counterclockwise and a pressure pad 65 disposed inside the endless belt 64 so as to face the heating roller 56. The belt travel guide 68 is provided on the inner side of the endless belt 64 and guides the travel of the endless belt 64. The pressure pad 65 and the belt traveling guide 68 are connected by a pressure pad support member 67.

  The pressure pad 65 is provided with a pressure bonding portion 66 along the outer peripheral surface of the heating roller 56, and the pressure bonding portion 66 is pressure bonded to the heating roller 56 via an endless belt 64.

  The pressure roller 58 rotates following the heating roller 56, and conveys the recording paper to the downstream side in the conveyance direction of the conveyance path W while nipping the recording paper with the heating roller 56 (nipping portion N). At this time, the toner on the recording paper is melted by the heat from the heating roller 56 and the pressure from the pressure roller 58, and the toner image is fixed on the recording paper. Then, the recording sheet is conveyed along the conveyance path W by the conveyance roller 69 arranged on the downstream side in the conveyance direction of the heating roller 56 and the pressure roller 58.

  The housing 54 is provided with a cooling fan 57 that cools the heating roller 56. The cooling fan 57 corresponds to the heat fixing member cooling means in the present invention.

  As shown in FIGS. 2 and 3, the temperature sensor unit 70 includes an IR temperature sensor 76 that detects the surface temperature of the heating roller 56 by detecting infrared rays emitted from the surface of the heating roller 56, and an IR temperature sensor 76. And a housing 72 that houses the IR temperature sensor 76 and the substrate 74. The IR temperature sensor 76 corresponds to a non-contact temperature sensor provided in the image forming apparatus of the present invention.

  A filter 82 that transmits infrared rays is attached to the surface of the housing 72 that faces the heating roller 56 to form an infrared window.

  The base 74 is connected to the control device 53, and the surface temperature of the heating roller 56 detected by the IR temperature sensor 76 is input to the control device 53. The controller 53 adjusts the current supplied to the halogen lamp 63 based on the detection result of the surface temperature of the heating roller 56 in the IR temperature sensor 76 so that the surface temperature of the heating roller 56 falls within a predetermined temperature range. Control. The surface temperature of the heating roller 56 detected by the IR temperature sensor 76 is also input to the central control computer 100 described later.

  The casing 72 includes a main body 72A and a lid portion 72B.

  A circular opening 80 is formed in the lid 72B, and a filter 82 is attached to the opening 80 to form an infrared window.

  A cleaning member 84 is provided on the surface of the lid 72B. The cleaning member 84 includes a long plate-like plate portion 86, and one end of the plate portion 86 is rotatably attached to the lid portion 72 </ b> B with a pin 85. A hole 86A is formed in the vicinity of the plate 85 where the pin 85 is attached, and one end of a tension spring 88 is locked in the hole 86A. The other end of the tension spring 88 is locked to a convex portion 87 installed on the lid portion 72B. Thereby, the plate portion 86 is biased counterclockwise by the tension spring 88.

  A sponge 94 for wiping the surface of the filter 82 is attached to the back surface of the plate portion 86. The plate portion 86 is rotated about the pin 85 by the solenoid 90 and the tension spring 88.

  A guide member 96 is installed in the lid portion 72B at a position where the other end of the plate portion 86 is held. The guide member 96 has an arc shape along the movement locus of the other end of the plate portion 86 when the plate portion 86 rotates about the pin 85. The guide member 96 has a substantially U-shaped cross section so as to sandwich the other end of the plate portion 86.

  The full-color printer 1000 further includes a central control computer 100 that controls the entire full-color printer 1000 and a temperature / humidity sensor 10 that detects the temperature and humidity inside the full-color printer 1000. The detection result in the temperature / humidity sensor 10 is input to the central control computer 100. The temperature / humidity sensor 10 corresponds to the temperature / humidity detection means in the present invention.

  Hereinafter, the operation of the full-color printer 1000 will be described.

  When the full-color printer 1000 is turned on, the central control computer 100 immediately determines whether or not the normal mode operation can be started according to the procedure shown in the flowchart of FIG.

  First, as shown in step S <b> 2 in FIG. 5, it is determined whether the surface temperature of the heating roller 56 detected by the IR temperature sensor 76 is equal to or higher than a predetermined temperature T.

  If the determination is Yes, it is considered that the surface temperature of the heating roller 56 is accurately detected without the filter 82 being clouded or the like in the temperature sensor unit 70, so the central control computer 100 proceeds to step S10. The full color printer 1000 is instructed to shift to normal mode operation. When the command is input, the full-color printer 1000 preheats the heating roller 56. When the heating roller is preheated to a temperature at which the toner image can be stably fixed, printing is performed while feeding the recording paper at a normal page interval. To do.

  On the other hand, if the determination is No, water drops are attached to the filter 82 in the temperature sensor unit 70 or the heating roller 56 is heated to a temperature sufficient to stably fix the recording paper-like toner image. Therefore, in step S4, the central control computer 100 determines whether or not the greenhouse in the full-color printer 1000 detected by the temperature / humidity sensor 10 is in a low temperature / high humidity region indicated by diagonal lines in FIG. Determine whether. Here, the low temperature and high humidity region is a temperature and humidity region where condensation is likely to occur in the temperature sensor unit 70.

  If the determination result in step S4 is Yes, it is considered that there is a possibility that condensation has occurred in the temperature sensor unit 70 and water droplets have adhered to the filter 82. Therefore, in step S6, the image forming unit 12 starts from the paper cassette 42. The full color printer 1000 is instructed to perform the recording sheet travel prohibition mode operation for prohibiting the travel of the recording sheet S from the transfer section 14 and the fixing section 16 to the discharge tray 52. When the command is input, the full-color printer 1000 stops the pickup sheet 44, the retard roller 46, the sheet conveying roller 48, the conveying roller 69, and the discharge roller pair 50 so that the recording sheet S is not conveyed and is heated. The roller 56 is preheated.

  On the other hand, if the determination result in step S4 is No, it is considered that water droplets are not attached to the filter 82, so the process proceeds to step S10, and the full-color printer 1000 is operated in the normal operation mode.

  Next, the central control computer determines whether or not a predetermined time t1 has elapsed since the transition to the recording paper travel inhibition mode in step S8. Here, the predetermined time t1 can be determined as the time required for the heating roller 56 to be sufficiently preheated and the water droplets on the surface of the filter 82 to evaporate.

  If judgment in Step S8 is Yes, it will transfer to Step S10 and will enter normal operation mode.

  On the other hand, if the determination in step S8 is No, the process returns to step S6 to continue the recording paper travel prohibition mode.

  As shown in FIG. 6, it may be determined in step S8 whether the temperature and humidity detected by the temperature and humidity sensor 10 is outside the low temperature and high humidity region shown in FIG. In this case, if the temperature / humidity is outside the low temperature / high humidity region, the process proceeds to step S10 to enter the normal operation mode, and if the temperature / humidity is within the low temperature / high humidity region, the process returns to step S6 to prohibit recording paper running. The mode should be continued.

  Further, instead of operating the full-color printer 1000 in the recording paper travel prohibition mode in step S6, the full color printer 1000 is operated in the thinning travel mode in which the page interval of the recording paper S, in other words, the transport interval is increased with respect to that in the normal operation mode. May be.

  Further, when the full-color printer 1000 is operated in the recording paper travel prohibition mode or the thinning travel mode, the amount of current supplied to the halogen lamp 63 that stops the cooling fan 57 or heats the heating roller 56 via the control device 53. May be increased so that the heating roller 56 is heated more rapidly.

  In the normal operation mode, the recording paper S is taken out from the paper cassette 42 at normal intervals by the pickup roller 44 and the retard roller 46 in accordance with a command from the central control computer 100 and introduced into the transfer unit 14 by the paper transport roller 48. . On the other hand, in the image forming unit 12, toner images of Y, M, C, and K colors are formed in the image forming units 24Y, 24M, 24C, and 24K. The Y and M toner images are transferred to the primary intermediate transfer drum 36A, and the C and K toner images are transferred to the primary intermediate transfer drum 36B. The toner images transferred to the primary intermediate transfer drum 36A and the primary intermediate transfer drum 36B are transferred to the secondary intermediate transfer drum 38 to form a full-color toner image. The full-color toner image is transferred to the recording paper S introduced into the transfer unit 14.

  The recording sheet S on which the full-color toner image is transferred is introduced into the fixing unit 16 and the toner image transferred by the transfer unit 14 is fixed. The recording sheet S on which the toner image is fixed is discharged to the discharge tray 52 by the discharge roller pair 50.

  The full color printer 1000 is operated in the recording paper travel prohibition mode or the thinning travel mode when the internal temperature and humidity are in the low temperature and high humidity region.

  Therefore, before the inside is sufficiently preheated, the recording paper S saturated with moisture in the air travels in a large amount, so that the inside of the full-color printer 1000 is saturated with water vapor from the recording paper S, and the temperature sensor unit 70 is It is possible to effectively prevent the occurrence of printing defects such as toner image fixing defects caused by condensation and the surface temperature of the heating roller 56 being unable to be measured accurately.

FIG. 1 is a schematic cross-sectional view showing the configuration of a full-color printer according to an example of the image forming apparatus of the present invention. FIG. 2 is a partially enlarged view showing details of the configuration of the fixing unit in the color printer of FIG. FIG. 3 is a perspective view showing details of the configuration of the temperature sensor unit in the fixing unit shown in FIG. FIG. 4 is a graph showing the temperature and humidity range in which the color printer of FIG. 1 is operated. FIG. 5 is a flowchart showing a procedure for determining whether or not the central control computer can immediately enter the normal mode operation in the full color printer of FIG. FIG. 6 is a flowchart showing another example of the determination procedure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Temperature / humidity sensor 12 Image forming part 14 Transfer part 16 Fixing part 16 2012Y Image forming unit 24M Image forming unit 24C Image forming unit 24K Image forming unit 56 Heating roller 58 Pressure roller 100 Central control computer 1000 Full color printer

Claims (9)

An image forming apparatus comprising: a heat fixing member that heats a recording sheet on which a toner image is transferred to fix the toner image on the recording sheet; and a non-contact temperature sensor that detects a surface temperature of the heat fixing member in a non-contact manner. Because
It has a temperature and humidity detection means for detecting the temperature and humidity inside the image forming apparatus,
When the temperature / humidity detecting means detects that the inside of the image forming apparatus has a temperature / humidity predetermined as a range in which the surface of the non-contact temperature sensor is condensed, the recording paper is prohibited from traveling. Image forming apparatus. An image forming apparatus comprising: a heat fixing member that heats a recording sheet on which a toner image is transferred to fix the toner image on the recording sheet; and a non-contact temperature sensor that detects a surface temperature of the heat fixing member in a non-contact manner. Because
It has a temperature and humidity detection means for detecting the temperature and humidity inside the image forming apparatus,
When the temperature / humidity detecting means detects that the inside of the image forming apparatus has a temperature / humidity set in advance as a range in which the surface of the non-contact temperature sensor is condensed, the page interval of the recording paper is set at the time of normal image formation. An image forming apparatus characterized in that it is wider than the page interval.   2. The image formation according to claim 1, wherein the prohibition of running of the recording paper is canceled after a predetermined time has elapsed as a time until the heat fixing member is heated to a temperature at which dew condensation does not occur in the non-contact temperature sensor. apparatus.   The page interval of the recording paper is narrowed to the page interval during normal image formation after a predetermined time has elapsed as a time until the heat-fixing member is heated to a temperature at which condensation does not occur in the non-contact temperature sensor. Item 3. The image forming apparatus according to Item 2.   When the temperature / humidity detecting means detects that the temperature / humidity inside the image forming apparatus is out of a predetermined range as the temperature / humidity on which the temperature detection surface of the non-contact temperature sensor is condensed, the recording paper is prohibited from traveling. The image forming apparatus according to claim 1, wherein:   When the temperature / humidity detecting means detects that the temperature / humidity inside the image forming apparatus is out of a predetermined range as the temperature / humidity on which the temperature detection surface of the non-contact temperature sensor is condensed, the page interval of the recording paper is set. The image forming apparatus according to claim 2, wherein the image forming apparatus reduces the page interval during normal image formation.   The temperature and humidity of the image forming apparatus includes a heat fixing member cooling unit that cools the heat fixing member, and the temperature and humidity are predetermined as a range in which the surface of the non-contact temperature sensor is condensed. The image forming apparatus according to claim 1, wherein when the detecting unit detects, the cooling of the heat fixing member by the heat fixing member cooling unit is stopped.   The heating rate of the heat fixing member is increased when the temperature / humidity detecting means detects that the inside of the image forming apparatus has a temperature / humidity predetermined as a range in which the surface of the non-contact temperature sensor is condensed. Item 8. The image forming apparatus according to any one of Items 1 to 7.   When the non-contact temperature sensor detects that the surface temperature of the heat fixing member is higher than a predetermined value, the temperature and humidity predetermined within the image forming apparatus as a range in which the surface of the non-contact temperature sensor is condensed The image forming apparatus according to any one of claims 1 to 8, wherein printing on a recording sheet is performed in a normal mode without determining whether or not the recording medium is in a normal mode.

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