JP2015172700A - Fixing device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device that has improved an energy-saving property and has reduced first print time.SOLUTION: There is provided a fixing device that includes a housing, a heating member arranged inside the housing, and a heating target member that is heated by the energized heating member, and detects the temperature of the heating target member with a non-contact temperature sensor provided on the outside of the housing through an opening provided in the housing, the fixing device further including opening opening/closing means capable of opening and closing at least a part of the opening.

Description

  The present invention relates to a fixing device of an electrophotographic image forming apparatus such as a copying machine, a printer, and a facsimile using an electrophotographic method, and an image forming apparatus including the fixing device.

  In recent years, there has been a strong demand for energy saving and high speed for image forming apparatuses such as printers, copiers, and facsimiles.

  In an image forming apparatus, an unfixed toner image is transferred to a recording material sheet, printing paper, photosensitive paper, electrostatic recording paper, etc. by an image transfer method or a direct method by an image forming process such as electrophotographic recording, electrostatic recording, and magnetic recording It is formed on a recording medium. As a fixing device for fixing an unfixed toner image, a contact heating method fixing device such as a heat roller method, a film heating method, and an electromagnetic induction heating method is widely used.

  As an example of such a fixing device, a belt-type fixing device (for example, Patent Document 1) and a surf fixing (film fixing) fixing device (for example, Patent Document 2) using a ceramic heater are known.

  In the belt-type fixing device, in recent years, further reduction in warm-up time and first print time is desired. Here, the warm-up time is the time required from the normal temperature state to a predetermined temperature (reload temperature) that can be fixed, such as when the power is turned on, and the first print time is the time after receiving a print request and undergoing print preparation. This is the time from when the printing operation is performed until paper discharge is completed.

  Further, as the speed of the image forming apparatus increases, the number of sheets to be passed per unit time increases and the required heat quantity increases, so that there may be a shortage of heat quantity (so-called temperature drop) particularly at the beginning of continuous printing.

  Surf fixing using a ceramic heater has been proposed as a method for shortening the time described above, and this method enables a reduction in heat capacity and size as compared with a belt-type fixing device. However, 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, so that fixing failure is likely to occur. In particular, in a high-speed machine, the fixing belt rotates fast, and the heat radiation of the belt outside the nip portion increases, so that fixing failure may occur more easily.

  In order to solve the above problems, in the configuration using an endless belt, the entire belt can be warmed, and the first print time from the heating standby time can be shortened. Furthermore, there has been proposed a fixing device that solves the shortage of heat at the time of high-speed rotation and can obtain good fixability even when mounted on a high-production image forming apparatus (Patent Document 3).

  FIG. 10 is a schematic diagram of a fixing device disclosed in Patent Document 3. A pipe-shaped metal heat conductor 112 is fixed inside the endless belt 101 so as to be able to guide the movement of the endless belt 101, and endlessly passed through the metal heat conductor 102 by the heat source 102 in the metal heat conductor 112. The belt 1 is heated. Further, a pressure roller 104 that forms a nip portion N in contact with the metal heat conductor 112 via the endless belt 101 is provided, and the endless belt 101 is moved in the circumferential direction as the pressure roller 4 rotates. Let With these configurations, it is possible to warm the entire endless belt constituting the fixing device, to shorten the first print time from the heating standby time, and to solve the shortage of heat at the time of high-speed rotation. ing.

  However, in order to achieve further energy saving and further shortening of the first print time, it is necessary to further improve the thermal efficiency. Therefore, a configuration has been devised in which the endless belt is directly heated (without the metal heat conductor) from the configuration in which the endless belt is indirectly heated via the metal heat conductor. With this configuration, it is possible to reduce the power consumption by greatly improving the heat transfer efficiency and to further shorten the first print time from the heating standby time. At the same time, the cost can be reduced by omitting the metal heat conductor.

  However, even in such a fixing device, further improvement in energy saving and further reduction in the first print time are desired.

  The present invention provides a fixing device that solves the above-described conventional problems, that is, can further improve energy saving and further reduce the first print time, and an image forming apparatus including such a fixing device. For the purpose.

  In order to solve the above-described problem, the fixing device of the present invention is heated by a housing, a heating member disposed in the housing, and the energized heating member as described in claim 1. A fixing member that detects a temperature of the member to be heated by a non-contact temperature sensor disposed outside the casing through an opening provided in the casing. An opening / closing means that can open and close at least a part is provided.

  The fixing device according to the present invention includes an opening opening / closing means provided to detect the temperature of a heated member disposed in the housing, and capable of opening and closing at least a part of the opening of the housing. Energy savings can be improved and the first print time can be further shortened.

FIG. 3 is a model diagram illustrating an example of a fixing device according to the present invention. It is a top view of a light shielding member. It is a model figure which shows another example of the fixing device of this invention. FIG. 3A is a perspective view. FIG. 3B is a front view. It is a model figure which shows the example by which the other cover member is arrange | positioned outside the housing | casing other than the fixing device of this invention. FIG. 3 is a model diagram showing a control relationship of the fixing device of the present invention. FIG. 3 is a model diagram illustrating a control relationship of an example of a fixing device including a temperature response preheating control unit according to the present invention. It is another model figure which shows the control relationship of the example of a fixing device provided with a close time preheating control means of this invention. FIG. 10 is another model diagram illustrating a control relationship of an example of a fixing device including an opening / closing suppression control unit according to the present invention. 1 is a model diagram illustrating an example of an image forming apparatus including a fixing device of the present invention. FIG. 10 is a model diagram illustrating an example of a conventional fixing device.

  An example of the configuration of the present invention is shown in FIG.

  This fixing device example 20 is mainly composed of the following members. A fixing belt 101 as an example of an endless belt-shaped fixing member. A nip forming member 106 as an example of a nip forming member that is inside the fixing belt 101 and rotatably holds the fixing belt 101 and is in sliding contact with the inner surface of the fixing belt 101 at the nip forming surface. A pressure roller 103 that is urged by a nip forming member via a fixing belt 101 as an example of a fixing member to rotate the fixing belt 101. Two halogen heaters 102 as an example of heating means for heating the fixing belt 101. A light shielding member 115 for shielding heat rays supplied from the halogen heater 102 to the fixing belt 101 in accordance with the width of the recording medium P supplied to the fixing device. In this example, a fixing device using a fixing belt as the member to be heated is shown, but a fixing device including a fixing sleeve instead of the fixing belt may be used.

  The plan view of the light shielding member 115 is shown in FIG. In this example, the light shielding member 115 is a plate-like member, and a notch is provided at the center thereof. The light shielding member 115 is driven in a vertical direction in FIG. 2 (coaxially with the fixing belt 101 in FIG. 1) by a driving unit (not shown) to partially block the heat rays from the halogen heater 102 and fix as a heated member. Only the necessary part of the belt 101 is heated. In the example shown here, a light shielding member is used. However, a plurality of heaters having different heating part lengths may be provided to enable partial heating without the light shielding member.

  The main part of the fixing device 20 is housed in a housing (unit case) C and is unitized as a fixing unit. The casing C is provided with an opening C <b> 1 near the fixing belt 101 so that the temperature of the fixing belt 101 can be measured from the outside of the casing C in order to control the temperature of the fixing belt 101. . The temperature of the fixing belt 101 is detected by a non-contact temperature sensor S such as a thermopile provided outside the housing C through the opening C1.

  In such a fixing device, it can be seen that an air flow flows into the housing C from the opening C1, the temperature of the fixing belt 101 is locally decreased, and abnormal images such as poor fixing and uneven gloss may occur. It was. Further, it has been found that the heat insulation effect of the entire fixing unit is lowered by the opening C1, energy saving is impaired, and the first print time is also increased.

  In order to cope with such an event, in the fixing device example 20 of the present invention shown in FIG. 1, a plate-like lid member 110 is provided so as to be rotatable coaxially with the fixing belt 101, and the lid member 110 opens the plate-like lid member 110. Part C1 can be opened and closed.

  Here, the appearance of an example of the fixing device of the present invention is shown in FIG. 3, FIG. 3 (a) is a perspective view of the fixing device having such a lid member, and FIG. 3 (b) is a front view thereof. The figure is shown. Openings C1 are provided near the center and near the right end of the front surface of the housing C, respectively, and both of these can be opened and closed by a lid member in the housing C, not shown.

  The lid member is preferably provided near the opening in the casing in order to obtain a high effect. However, the lid member may be provided outside the casing C, for example, in the main body of the image forming apparatus adjacent to the fixing device. FIG. 4 shows an example in which a lid member 110 ′ that is driven in a vertical direction in the figure in a rack-and-pinion manner is provided in the opening C 1 outside the casing C.

  Further, the non-contact type temperature sensor S may be provided in the fixing device itself as long as it is outside the casing C, or may be provided in the image forming apparatus main body adjacent to the fixing device. In the example shown in FIG. 4, two non-contact temperature sensors and openings are provided, but the number is not limited to two. It may be provided. Further, even if the lid member is long in the fixing belt axial direction so as to cover all of the plurality of openings, the lid member is provided with a plurality of lids covering each of the plurality of openings, or covers a part of the openings. There may be.

  These lid members are opened and closed by a control device of the fixing device. Here, an example of control of the lid member by the control device of such a fixing device will be described with reference to FIG. 5 which is a model diagram.

  In FIG. 5, the fixing belt 101 which is an example of a member to be heated is heated by energizing a halogen heater 102 which is an example of a heating member connected to a heating power source PW. Note that the fixing belt is rotationally driven during heating and preheating described later to prevent local overheating.

  The temperature of the fixing belt 101 is detected by a non-contact temperature sensor S provided outside the casing C through an opening C1 provided in the casing C. A lid member 110 for opening and closing the opening C1 is driven in the vertical direction in the figure by a lid member driving device M which is a motor. Here, the lid member 110 and the lid member driving device M constitute an opening portion opening / closing means for opening and closing the opening portion C1.

  By such opening and closing means, the opening C1 is closed except when the temperature is measured by the non-contact temperature sensor S, so that a local decrease in the temperature of the fixing belt 101 and abnormal images such as poor fixing and uneven gloss are observed. Can be generated. In addition, energy saving is improved and the first print time can be shortened.

  The control device K of the fixing device is necessary for a control device such as an arithmetic circuit CPU, a program for realizing various control means, a ROM, a RAM, a timer, various I / O ports, relays, etc. in which each predetermined value is recorded in advance. Equipment, and controls the temperature and drive of the fixing device.

  The lid member driving device M is controlled by the opening / closing control means K1 in the control device K. That is, the lid member driving device M drives the lid member 110 to open and close the opening C1 in accordance with the opening / closing instruction signal sent by the signal line L1 connected to the opening / closing control means K1.

  In the example of the fixing device shown in FIG. 5, the control device K has the following heating control means K2. The heating control means K2 receives the opening / closing information of the lid member 110 from the opening / closing control means K1 through the signal line L2. When the opening C1 is closed, the energization for the fixing operation to the halogen heater 102 by the heating power source PW is not performed.

  The heating control means K2 receives the temperature information of the fixing belt 101 by the non-contact temperature sensor S from the signal line L7 when energizing for the fixing operation, and controls the heating power supply PW connected to the halogen heater 102, The fixing belt 101 is maintained at a temperature suitable for fixing.

  With such a configuration, when the temperature of the fixing belt 101 is not detected by the non-contact temperature sensor S, heating for the fixing operation is not performed, and as a result, overheating of the fixing belt 101 is prevented in advance. The

  The fixing device control device K in this example of the fixing device further includes the following opening / closing control means K4. That is, the opening opening / closing control means K4 starts a fixing start signal at the start of image fixing and / or a loading start at the start of loading of a recording medium from a control device of an image forming apparatus (not shown) provided with this fixing device example. Each signal is received by the signal line L0.

  The opening / closing control means K4 opens the opening C1 at the start of image fixing and closes it at the end of fixing, opens at the start of loading of the recording medium into the fixing device and closes at the end of loading, or The opening opening / closing means is controlled so as to open and close at any time.

  That is, when the opening opening / closing control means K4 receives these fixing start signal and carry-in start signal, the opening opening / closing control means K4 moves the lid member 110 upward in this figure to the opening / closing control means K1 through the signal line L8. Then, the opening C1 is opened. At the same time or before and after, the rotating belt 101 and the pressure roller (not shown) are rotationally driven by the control means (not shown) of the control means K of the fixing device. Then, after the image is fixed or after the recording medium is brought into the fixing device 20, the opening / closing control means K4 controls the opening / closing control means K1 to close the opening C1. At the same time, the driving of the rotating belt 101 and the pressure roller (not shown) is stopped. In this example, the opening C1 is closed at the end of fixing or at the end of unloading. However, the opening may be closed during standby of the fixing device and / or in the energy saving mode.

  With such a configuration, it is possible to reliably control the temperature of the fixing belt 101 during the fixing operation and the conveyance of the recording medium.

  In the example of the fixing device as described above, if the temperature of the fixing belt 101 is high immediately after the end of the fixing operation, or if the opening C1 is closed by the lid member 110 as it is, the life of the member such as the fixing belt is affected. There is concern.

  Here, the opening / closing control means K4 has the following control function, so that the above-mentioned concerns can be eliminated. That is, when the opening / closing means closes the opening C1, when the measured temperature of the fixing belt 101 is higher than, for example, a predetermined temperature considered to have little influence on the lifetime, the opening / closing control means K4. Is a control for delaying the timing for closing the opening. During the delay, the control means (not shown) of the control device K of the fixing device controls the driving of the fixing belt 101 and prevents the fixing device member from overheating until the opening C1 is closed. The driving is continued. Note that the delay control may be delayed until the temperature becomes equal to or lower than the predetermined temperature, or may be delayed until a predetermined time is reached.

  The control device K of the fixing device preheats the member to be heated by the heating member under a predetermined condition when the opening is closed and energization for fixing is not performed for preheating the fixing belt. Preheating control means may be provided.

  That is, in the example shown in FIG. 5, the preheating control means K3 receives the opening / closing information of the opening C1 and the presence / absence of heating of the fixing belt 101 for the fixing operation from the opening / closing control means K1 through the signal line L5. Then, the fixing belt 101 is preheated when the opening C1 is closed and the temperature of the fixing belt 101 is not increased for image fixing, and preheating is required. In other words, the halogen power source 102 is energized by controlling the heating power supply PW with a predetermined condition (predetermined energization amount, continuous or predetermined intermittent condition) for preheating by the signal line L6. Since the fixing belt 101 is preheated by the energization for preheating, the time required for raising the temperature to the actual fixing operation temperature is shortened. When the fixing belt 101 is preheated, the fixing belt 101 is rotated by a control means (not shown) of the control device K of the fixing device.

  However, in this method, there may be a case where the fixing belt 101 does not reach an appropriate temperature for preheating due to conditions such as an outside air temperature or an installation location.

  In the example shown in FIG. 6 (the control means and signal lines that are not directly described in this example are not shown. The same is omitted in FIGS. 7 and 8), the control device K includes the fixing belt 101. The following temperature response preheating control means K5 for performing preheating at an appropriate temperature is provided.

That is, the temperature responsive preheating control means K5 is when preheating is required when the opening C1 is closed by the signal line L9 from the opening / closing control means K1 and the temperature of the fixing belt 101 is not increased for image fixing. Get notified. The temperature response preheating control means K5 controls the opening portion opening / closing means K1 through the signal line L9 to open the opening portion C1 and then close it. At the time of opening and closing, the temperature response preheating control means K5 obtains the temperature information of the fixing belt 101 from the non-contact temperature sensor S through the signal line L11. The temperature response preheating control means K5 selects and determines the energization condition (preheating condition) for preheating the fixing belt 101 according to the temperature of the fixing belt 101 from predetermined conditions. Then, the heating power supply PW is controlled by the signal line L10, and the fixing belt 101 is preheated by the halogen heater 102 under the preheating conditions. By such temperature response preheating control means K5, the fixing belt 101 can be preheated at an appropriate temperature or a temperature close to the appropriate temperature. The series of operations of opening / closing the opening C1, determining the preheating condition, and preheating under the preheating condition can be repeated not only once but, for example, periodically, and at that time, the fixing belt 101 can be preheated at an appropriate temperature or at a temperature closer to the appropriate temperature.

  Further, the control device K may have the following closing preheating control means shown in FIG. 7 instead of the temperature response preheating control means K5 as described above. FIG. 7 shows an example in which the closing preheating control means K6 is provided.

  In the example shown in FIG. 7, a second temperature sensor S <b> 2 that measures the ambient temperature in the housing C is provided.

  The closing preheating control means K6 receives the ambient temperature in the housing C measured by the second temperature sensor S2 through the signal line L12. In addition, the signal line L12 notifies the opening / closing control means K1 that the opening C1 is closed and the fixing belt 101 is not heated for image fixing, and that preheating is required.

  The closing preheating control unit K6 preheats the fixing belt 101 by the halogen heater 102 by controlling the heating power supply PW through the signal line L13 according to a predetermined preheating condition according to the ambient temperature in the housing C.

  In each of the above examples, the opening C1 is opened and closed by the lid member 110. At this time, a driving sound or the like is generated. When the image forming apparatus is required to be quiet, an open / close suppression control unit as shown in FIG. 8 may be provided as necessary.

  The opening / closing suppression control means K8 follows the opening / closing conditions input in advance by the operator through the setting panel PN connected by the signal line L17. As such opening / closing conditions, opening / closing of the opening C1 is not performed at all, or the opening / closing frequency is reduced to, for example, once every three times, and further, the opening C1 from the opening / closing control means S1 is opened / closed. All opening and closing are performed according to the opening / closing signal.

  The opening / closing suppression control means K8 is connected to the lid member driving device M by a signal line L18. When an opening / closing signal for opening / closing the opening C1 from the opening / closing control means S1 is received by the signal line L18, the opening / closing of the opening C1 is controlled according to the set opening / closing conditions.

  The example of the fixing device shown in FIGS. 1 to 8 described above can be used by being incorporated in an image forming apparatus like the conventional fixing device.

  An example of such an image forming apparatus is shown in FIG.

  The image forming apparatus shown in FIG. 9 is a color printer that uses a tandem system in which image forming units for forming a plurality of color images are juxtaposed along the belt extending direction. However, the present invention is not limited to this method, and can be applied not only to a printer but also to a copying machine, a facsimile machine, and the like.

  In FIG. 10, the image forming apparatus 1 has a tandem structure in which photosensitive drums as image carriers capable of forming images as images corresponding to colors separated into yellow, cyan, magenta, and black are arranged in parallel. Is adopted.

  In the image forming apparatus 1 having the configuration shown in FIG. 10, visible images are formed on the photosensitive drums 4Y, 4C, 4M, and 4Bk. A primary transfer process is performed on a transfer belt (intermediate transfer member) 30 that uses an endless belt that can move in the direction of the arrow while facing the photosensitive drums 4Y, 4C, 4M, and 4Bk. Superimposed transfer. Thereafter, batch transfer is performed by performing a secondary transfer process on the recording medium S using a recording sheet or the like.

  Around each photosensitive drum, an apparatus for image forming processing is arranged according to the rotation of the photosensitive drum. Here, the photosensitive drum 4Bk that performs black image formation will be described as an object. A charging device, a developing device, a primary transfer roller 31Bk, and a cleaning device that perform image forming processing are arranged along the rotation direction of the photosensitive drum 4Bk. For the writing performed after charging, the optical writing device 9 is used.

  The transfer to the transfer belt 30 is performed so that the visible images formed on the photosensitive drums are transferred to the same position on the transfer belt 30 while the transfer belt 30 moves in the arrow direction. That is, the timing is shifted from the upstream side in the direction toward the downstream side by the voltage application by the primary transfer roller 31 disposed so as to face the respective photosensitive drums with the transfer belt 30 interposed therebetween.

  The image forming apparatus 1 has the following configuration. A transfer belt unit (transfer device) 3 including four image stations that perform image formation processing for each color, and a transfer belt 30 and a primary transfer roller 31 that are arranged to face each photoconductor drum. A secondary transfer roller 36 that is a transfer roller as a transfer member that is disposed to face the transfer belt 30 and is driven by the transfer belt 30. An intermediate transfer belt cleaning device 35 disposed opposite to the transfer belt 30 and cleaning the transfer belt 30. An optical writing device 9 as an optical writing device disposed facing the lower side of these four image stations.

  The optical writing device 9 is equipped with a semiconductor laser as a light source, a coupling lens, an fθ lens, a toroidal lens, a folding mirror, a rotating polygon mirror as a deflecting means, and the like. Then, writing light corresponding to each color is emitted to each photosensitive drum to form an electrostatic latent image on the photosensitive drum.

  The image forming apparatus 1 has the following configuration. A sheet feeding device as a paper feeding cassette on which recording paper P conveyed between the photosensitive drum and the transfer belt 30 is loaded. A registration roller that feeds the recording paper P conveyed from the sheet feeding device toward a transfer portion between each photosensitive drum and the transfer belt 30 at a predetermined timing in accordance with a toner image formation timing by the image station. Pair 12. A sensor (not shown) that detects that the leading edge of the recording paper P has reached the registration roller pair 12.

  The image forming apparatus 1 has the following configuration. The fixing device illustrated in FIG. 1 (any of the fixing devices shown in FIGS. 2 to 9 may be used). A paper discharge roller 13 that discharges the fixed recording paper P to the outside of the main body of the image forming apparatus 1. A paper discharge tray 14 disposed on the main body of the image forming apparatus 1 and on which the recording paper P discharged from the main body of the image forming apparatus 1 by a paper discharge roller 13 is stacked. Toner bottles 9Y, 9C, 9M, and 9k that are located below the paper discharge tray 14 and are filled with toners of yellow, cyan, magenta, and black.

  In addition to the transfer belt 30 and the primary transfer roller 31, the transfer belt unit 3 includes a driving roller and a driven roller on which the transfer belt 30 is wound.

  The driven roller also has a function as tension urging means for the transfer belt 30. For this reason, the driven roller is provided with urging means using a spring or the like. The transfer belt unit 3 includes the transfer belt unit 3, the primary transfer roller 31, the secondary transfer roller 36, and the intermediate transfer belt cleaning device 35.

  The sheet feeding device is disposed at the lower part of the main body of the image forming apparatus 1 and includes a feeding roller 11 as a paper feeding roller that contacts the upper surface of the uppermost recording paper P. Then, the uppermost recording sheet S is fed toward the registration roller pair 12 by driving the feeding roller 11 counterclockwise.

  Although not shown in detail, the intermediate transfer belt cleaning device 35 provided in the transfer belt unit 3 includes a cleaning brush and a cleaning blade disposed so as to face and contact the transfer belt 3. . The transfer belt 30 is cleaned by scraping and removing foreign matters such as residual toner on the transfer belt 30 with a cleaning brush and a cleaning blade.

  The intermediate transfer belt cleaning device 35 also has a discharge means (not shown) for carrying out and discarding the residual toner removed from the transfer belt 30.

  Although the present invention has been described with reference to the preferred embodiment, the electric device of the present invention is not limited to the configuration of the above embodiment.

  A person skilled in the art can appropriately modify the electrical device of the present invention in accordance with conventionally known knowledge. Of course, such modifications are included in the scope of the present invention as long as the configuration of the electric apparatus of the present invention is provided.

C casing C1 opening K fixing device control device K1 opening / closing control means K2 heating control means K3 preheating control means K4 mouth opening / closing control means K5 temperature response preheating control means K6 closing preheating control means L1 to L3, L5 to L18 signals Line L4 Wiring M Lid member driving device PW Heating power supply PN Setting panel S Non-contact temperature sensor S2 Second temperature sensor 20 Example of fixing device 101 Fixing belt 106 Nip forming member 103 Pressure roller 102 Halogen heater 110, 110 ′ Lid member 115 light shielding member

JP 2004-286922 A Japanese Patent No. 2861280 JP 2007-334205 A

Claims (10)

An opening provided in the casing, the casing including a heating member disposed in the casing, and a heated member heated by the energized heating member. In a fixing device that detects by a non-contact type temperature sensor arranged outside the casing through a section,
A fixing device comprising: an opening / closing means for opening and closing at least a part of the opening.   The fixing device opens the opening at the start of image fixing and closes at the end of fixing, or opens at the start of loading of the recording medium into the fixing device and closes at the end of loading, or any of these. The fixing device according to claim 1, further comprising an opening / closing control unit that controls the opening / closing unit so that the opening / closing unit is also opened and closed.   When the opening opening / closing means closes the opening, and the temperature of the heated member measured by the non-contact temperature sensor is higher than a predetermined temperature, the opening opening / closing control means The fixing device according to claim 2, wherein the fixing device is controlled by delaying a closing time.   In accordance with a condition input by an operator, an opening / closing suppression control means is provided for performing some control of whether to open / close the opening by the opening / closing control means or reduce the opening / closing frequency of the opening. The fixing device according to claim 2, wherein the fixing device is a fixing device.   The fixing device according to claim 1, further comprising a heating control unit that does not energize the image for fixing when the opening is closed.   Preheating control means is provided for energizing the heating member to preheat the heated member under a predetermined condition when the opening is closed and energization for image fixing is not performed. The fixing device according to any one of claims 1 to 5.   When the opening is closed and energization for image fixing is not performed, the opening opening / closing means is controlled to open and close the opening, and the opening and closing is measured by the non-contact temperature sensor. A temperature responsive preheating control means for determining a preheating condition for preheating the heated member according to the temperature of the heated member, and for energizing the heated member to preheat the heated member according to the preheating condition. The fixing device according to claim 1, wherein A second temperature sensor for measuring the ambient temperature in the housing;
When the opening is closed and energization for image fixing is not performed, the heating member is heated on the heating member under a condition corresponding to the ambient temperature in the housing measured by the second temperature sensor. Closed preheating control means for energizing to preheat the member;
The fixing device according to claim 1, further comprising:   An image forming apparatus comprising the fixing device according to claim 1. A housing, a heating member disposed in the housing, and a heated member that is energized for image fixing and is heated by the heating member, wherein the temperature of the heated member is determined by the housing In an image forming apparatus provided with a fixing device that detects by a non-contact temperature sensor disposed outside the housing through an opening provided in the housing,
An image forming apparatus comprising: an opening / closing means that can open / close at least a part of the opening.

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