JP2015079045A - Fixing apparatus and image forming apparatus having the same - Google Patents

Abstract

A fixing device capable of realizing energy saving by shortening the warm-up time and reducing the power during passage of a recording material, and an image forming apparatus including the same. Halogen lamps 105a and 105b are disposed inside a rotatable fixing roller 101 that is in sliding contact with a recording material, and the fixing roller 101 absorbs wavelengths emitted from the halogen lamps 105a and 105b on the inner surface of the fixing roller 101. 101 is a fixing device that applies and forms an endothermic paint that transfers heat to 101 and fixes the unfixed toner image of the recording material by the heat of the fixing roller 101 that has been transferred, and the color of light emitted from the halogen lamps 105a and 105b. The temperature is 2450K or higher. Further, the spectral characteristics of the endothermic paint are assumed to have an absorptance of 90% or more for a wavelength of 2.5 μm or less. [Selection] Figure 2

Description

  The present invention relates to a fixing device that heats and fixes an unfixed toner image on a recording material such as recording paper in an image forming apparatus including a copying machine, a printer, a facsimile, and the like.

  As a conventional fixing device, although not shown in the drawing, an unfixed toner image of a recording material is passed through a nip portion formed between a pair of fixing rollers and a pressure member (pressure roller). A roller pair type apparatus for fixing a toner image is known. The fixing roller of this fixing device has a halogen lamp disposed as a heating source inside a metal hollow core metal made of, for example, aluminum and the like, and is not shown by a signal of a temperature sensor (thermistor) provided near the surface of the roller. The surface temperature of the roller is kept constant by controlling the halogen lamp ON / OFF by the temperature control circuit. An inner surface of the fixing roller is coated with an endothermic paint that converts light from the halogen lamp into heat.

  As the pressure roller, a type in which a heat-resistant elastic layer such as silicone rubber is covered as a coating layer on a core metal is used. This heat-resistant elastic layer is elastically deformed to form a predetermined nip portion when the pressure roller and the fixing roller are pressed against each other, and an unfixed toner image of the recording material passes through the nip portion and is heated. The toner image is fixed by being melted.

  By the way, in order to shorten the warm-up time, there are provided fixing devices and the like that can shorten the warm-up time by reducing the heat capacity of the fixing roller and efficiently supplying energy from the heating source to the fixing roller. Patent Document 1 discloses a method for efficiently heating a fixing roller and the like. By increasing the color temperature of the halogen lamp, the heat conversion efficiency during heating is improved and the warm-up time of the fixing device can be shortened. It is described that it is.

  In Patent Document 1, in order to reduce the rise time of the filament itself, the heat capacity is reduced by thinning the filament. The filament diameter and length are determined by the emission width, voltage, and power. However, if the rating (voltage and power) of the halogen lamp is determined, the resistance is determined, so that the diameter and length can be adjusted.

  For example, Patent Document 1 describes that if a filament having a wire diameter of 80% is used, the length is 64% and the heat capacity is 41% for producing a halogen lamp having the same resistance. That is, if the wire diameter is 80%, the time required to bring the filament to the same temperature with the same calorific value is reduced to 41%. In this way, when the filament is thinned, the color temperature increases.

Japanese Patent No. 3668149

  However, when the color temperature of the halogen lamp is increased, the filament diameter is reduced, which causes a problem that the life cycle is shortened. In addition, the spectral characteristics of halogen lamps shift to the short wavelength side, but when shifted to the short wavelength side, the light of the halogen lamp is converted into heat, so the characteristics of the endothermic paint formed on the inner surface of the fixing roller, specifically In this case, the light absorption rate on the short wavelength side is lowered.

  The present invention has been made in view of the above, and provides a fixing device capable of realizing energy saving by reducing power during passage of a recording material and an image forming apparatus including the same. The purpose is that.

In the present invention, in order to solve the above problems, a heating source is disposed inside a rotatable heating member that is in sliding contact with the recording material, and the heating member absorbs the wavelength emitted from the heating source to the heating member. An apparatus for forming an endothermic paint that transfers heat and fixing an unfixed toner image on the recording material by the heat of the heated heating member,
The color temperature of the light emitted from the heating source is set to 2450K or higher,
The spectral characteristics of the endothermic paint are characterized in that the absorptance with respect to a wavelength of 2.5 μm or less is 90% or more.

Note that the warm-up time of the fixing device is preferably 10 seconds or less.
Further, the heating member can be a low heat capacity roller.
In addition, a rotatable belt is brought into contact with the heating member, the heat of the heating member is supplied to the belt to heat the belt, and the unfixed toner image on the recording material can be fixed by the heat of the belt.

  Furthermore, in the present invention, in order to solve the above problems, the image forming apparatus is provided with the fixing device according to any one of claims 1 to 4.

  According to the present invention, for example, when a halogen lamp is used as a heating source, the conventional halogen lamp is 2400K, but when the color temperature of the halogen lamp is low, the spectral distribution shifts to the longer wavelength side. On the other hand, the light transmittance of the quartz glass constituting the halogen lamp is approximately 90% or more at 2.5 μm or less, but the light transmittance is drastically decreased at 2.5 μm or more. Therefore, when the color temperature of the halogen lamp is increased and shifted to the short wavelength side, the absorption rate of the inner surface coating of the heating member is reduced.

  However, at the same time as the above color temperature is increased, if an inner surface paint having a high absorption rate is used even on the short wavelength side, heat absorption characteristics to the heating member can be maintained and heat loss in the glass tube of the halogen lamp can be reduced. It is possible to shorten the warm-up of the fixing device. If a halogen lamp is used as the heating source, the rise time at the start of heating is fast, so that the heating member can be heated instantaneously, and the heating member can be heated efficiently at low cost.

  According to the second aspect of the present invention, there is a problem that when the color temperature of the halogen lamp as the heating source is increased, the life of the halogen lamp is shortened. Even if the halogen lamp is turned off immediately, there is no problem in terms of usability. Therefore, by raising the color temperature of the halogen lamp, there are few problems even if the life of the halogen lamp is shortened.

  According to the third aspect of the present invention, if the heat capacity of the heating member is large, the warm-up time becomes long. Therefore, it is necessary to turn on the halogen lamp even during standby after the job ends, which affects the life of the halogen lamp. However, when combined with a fixing device comprising a low heat capacity roller, the heat generated inside the heating member can be rapidly transferred to the surface of the heating member, so the warm-up time can be reduced to 10 seconds or less. it can. Also, even if the halogen lamp is turned off during standby, there is no problem in terms of usability. Therefore, by raising the color temperature of the halogen lamp, there are few problems even if the life of the halogen lamp is shortened.

  According to the invention described in claim 4, since the belt can be heated instantaneously by bringing the heat generated by the heating member into contact with the belt having a small heat capacity and heating it, shortening of the warm-up time can be expected.

  According to the fifth aspect of the present invention, the warm-up time of the image forming apparatus can be shortened, and the power consumption during standby is not necessary, so that an image forming apparatus with low power consumption can be obtained. is there.

1 is an internal configuration diagram showing a configuration of an image forming system in an embodiment of an image forming apparatus according to the present invention. 1 is a cross-sectional view schematically showing an embodiment of a fixing device according to the present invention. FIG. 4 is an explanatory diagram viewed from the axial direction of the fixing roller in the embodiment of the fixing device according to the present invention. 6 is a graph showing a relationship between a color temperature of a halogen lamp and a spectral distribution in an embodiment of a fixing device according to the present invention. It is a graph which shows the light transmittance of the quartz glass of the halogen lamp in embodiment of the fixing device which concerns on this invention. It is a table | surface which shows the measurement result of the light absorption rate of the endothermic paint in embodiment of the fixing device which concerns on this invention. 6 is a table showing the results of examining conditions for changing the inner surface coating of the fixing roller and the color temperature of the halogen lamp in the embodiment of the fixing device according to the present invention to reduce the warm-up time to 10 seconds or less. FIG. 6 is a cross-sectional explanatory view schematically showing a belt fixing device in another embodiment of the fixing device according to the present invention.

  An embodiment of the present invention will be described with reference to FIG. FIG. 1 is an internal configuration diagram showing a configuration of an image forming system 1 according to an embodiment of the present invention. The image forming system 1 includes a scanner 3, an automatic document conveying device 4, a post-processing device 5, a recording material supply device 6, a relay conveying unit 8, and a double-sided conveying device 10, each of which is a peripheral device, with the image forming device 2 as a core. Connected and extended functionality. Among these, the image forming apparatus 2 and the post-processing apparatus 5 are placed side by side on the upper surface of the recording material supply apparatus 6, and the scanner 3 is placed above them together with the automatic document feeder 4 disposed above the system 3. It is arranged by being supported on the rack 7.

  The image forming apparatus 2 has a function of recording and outputting image data from an externally connected device when an image processing device such as a personal computer is connected as an externally connected device as well as an image output of the image read by the scanner 3 To do. An electrophotographic process section (image forming section) 20 centered on a photosensitive body (photosensitive drum) 200 is disposed substantially on the left side of the center of the image forming apparatus 2.

  Around the photosensitive member 200, there are a charging roller 201 for uniformly charging the surface of the photosensitive member 200, an optical scanning unit 22 for scanning an optical image on the uniformly charged photosensitive member 200 and writing an electrostatic latent image, and this. A developing unit 202 that reproduces the electrostatic latent image written by the optical scanning unit 22 with a developer, a transfer unit 203 that transfers an image reproduced on the photosensitive member 200 onto a recording material such as recording paper, and a photosensitive material after transfer. A cleaning unit 204 that enables the developer remaining on the body 200 to be removed and a new image to be recorded on the photoconductor 200, and a charge removal lamp unit (not shown) that removes charges on the surface of the photoconductor 200. Etc. are arranged.

  A recording material supply unit 21 that can store a recording material such as recording paper is disposed below the image forming apparatus 2, that is, on the recording material supply device 6 side. The recording material supply unit 21 includes a recording material storage tray 210 that stores recording materials, and a separation supply unit 211 that separates and feeds the recording materials stored in the recording material storage tray 210 one by one. . The recording materials separated and fed one by one by the separation supply unit 211 are sequentially supplied between the photoconductor 200 and the transfer unit 203 of the electrophotographic process unit 20, and the toner image recorded and reproduced on the photoconductor 200. Is transcribed.

  Note that operations such as replenishment of the recording material and replacement of the recording material to the recording material supply unit 21 are performed by pulling out the recording material accommodation tray 210 on the front side of the main body of the image forming apparatus 2.

  A recording material sent from an optional recording material supply device 6 is received on the lower surface of the main body of the image forming apparatus 2, and is directed between the photoconductor 200 of the electrophotographic process unit 20 and the transfer unit 203. A recording material receiving port 27 for sequentially supplying the recording material is provided.

  Above the electrophotographic process unit 20, a fixing device 23 for fixing an unfixed toner image on the recording material is disposed. The recording material onto which the image has been transferred is sequentially received, and the developer transferred onto the recording material is heated and fixed. Thus, it functions to feed the recording material out of the fixing device 23. The recording material on which the image is recorded is delivered from the discharge roller 28 of the image forming apparatus 2 to the relay conveyance unit 8 on the upper surface of the main body of the image forming apparatus 2. As described above, the sheet conveyance path (recording material conveyance path) 64 of the image forming apparatus 2 is configured in a substantially vertical shape from the bottom to the top.

  The optical scanning unit 22 is disposed on the side of the electrophotographic process unit 20, that is, at a position adjacent to the electrophotographic process unit 20 in a direction substantially perpendicular to the sheet conveyance path 64. In the upper and lower spaces of the optical scanning unit 22, a device control unit 24 for accommodating a process control unit (PCU) substrate for controlling the electrophotographic process and an interface substrate for receiving image data from the outside of the device are received from the interface substrate. An image control unit 25 having an image control unit (ICU) substrate for performing predetermined image processing on the obtained image data and causing the optical scanning unit 22 to scan and record the image on the photosensitive member 200, and the various types A power supply unit 26 and the like for supplying power to the substrate and the unit are arranged.

  The recording material supply device 6 is an external recording material supply device attached as an option, and includes three recording material supply units 61, 62, and 63. In the plurality of recording material supply units 61, 62, and 63, the recording materials stored in the recording material storage trays 610, 620, and 630 are separated one by one by the separate feeding means 611, 621, and 631 provided respectively. Then, the recording material is supplied toward the recording material discharge port 65 provided on the upper surface of the recording material supply device 6 and communicating with the recording material receiving port 27 of the image forming apparatus 2. At the time of operation, the recording material supply units 61, 62, and 63 that accommodate a recording material of a desired size are selectively operated. The recording material is supplied to the recording material supply units 61, 62, and 63 by pulling out the recording material storage trays 610, 620, and 630 to the front side of the unit main body.

  In addition, the recording material supply device 6 is configured to place the image forming device 2 and the post-processing device 5 on the upper portion, but can be moved and fixed between the system racks 7 in this state. As described above, a moving roller 69 and a fixed portion 68 are disposed at the lower portion. At the time of movement, the fixing portion 68 is rotated and raised to separate the fixing portion 68 from the floor surface. At the time of fixing, the fixing portion 68 is rotated and lowered to bring the fixing portion 68 into contact with the floor surface. The recording material supply device 6 is fixed.

  1 illustrates the case where the recording material supply device 6 includes three recording material supply units 61, 62, and 63. However, the present invention is not limited to this, and the recording material supply device 6 includes at least one recording material supply unit. As long as it has.

  The post-processing device 5 has a function of introducing a recording material on which an image discharged from the image forming apparatus 2 and the relay conveyance unit 8 is recorded by a carry-in roller 50 provided at an upper portion and performing post-processing on the recording material. To do. Examples of post-processing include stapling, punching, and sorting. The post-processing device 5 illustrated in FIG. 1 performs stapling, and the post-processing is performed at the lower stage. What is not post-processed to the tray 59 is selectively discharged to the upper discharge tray 56 by the switching gate 52.

  The scanner 3 includes an automatic reading mode in which a sheet-like document automatically supplied by the automatic document feeder 4 is sequentially exposed and scanned one by one to read a document image, and a book-like document set by a user's manual operation. Or a manual reading mode for reading a document image of a sheet-like document that cannot be automatically supplied by the automatic document feeder 4. Then, exposure scanning is performed by the first scanning unit 31 and the second scanning unit 32 that move the document image of the document set on the transparent document mounting table 30 along the document mounting table 30 with a predetermined speed relationship with each other. Then, it is guided by an optical component such as a mirror or an imaging lens 33 to form an image on the photoelectric conversion element 34, so that the original image is converted into an electrical signal and output.

  The automatic document conveying device 4 includes a document conveying means 41 that conveys a document placed on the document setting tray 40 toward the document placing table 30 and discharges the scanned document onto a document discharge tray 42. Yes. Further, the automatic document feeder 4 rotates upward with the rear side of the apparatus as a fulcrum so that a sheet-like document that cannot be automatically supplied can be placed on the document table 30 and scanned. The front side is configured to open.

  The relay conveyance unit 8 is mounted on an upper portion of a paper discharge tray 29 provided on the top of the image forming apparatus 2 and forms a recording material on which an image discharged from the paper discharge roller 28 of the image forming apparatus 2 is recorded. This is a transport unit for introduction toward the post-processing device 5 located on the downstream side of the device 2. In the middle of the recording material conveyance path 84 of the relay conveyance unit 8, there is another recording material conveyance path 83 for guiding the recording material to the discharge tray 9 formed by the upper surface 82 of the unit and the upper surface 54 of the post-processing device 5. Branched and formed. The two discharge destinations can be changed by switching the gate 81 arranged at the branch portion of the transport path.

  The double-sided conveying device 10 is a conveying device that is attached to the side surface of the image forming apparatus 2 and reverses the recording material when forming images on both sides of the recording material. When reversing the recording material, the paper discharge roller 28 stops in a state where the recording material has been discharged halfway, and reversely reverses to guide the recording material to the double-sided conveyance device 10 side. At this time, by switching the gate 85 provided after the fixing device 23, the recording material does not return to the fixing device 23 side but enters the duplex conveying device 10. The recording material that has passed through the double-sided conveyance device 10 enters the paper conveyance path 64 again from before the electrophotographic process unit 20 and passes through the electrophotographic process unit 20 and the like, whereby an image is formed on the back surface.

  The image forming system 1 has a structure in which the image forming apparatus 2 and the post-processing apparatus 5 are mounted side by side on the recording material supply apparatus 6. The main body width dimension of the image forming apparatus 2 is L 1, and the post-processing apparatus. 5 is designed so that the width L of the recording material supply device 6 is substantially equal to L1 + L2. By configuring the system by combining peripheral devices as in the image forming system 1, an image forming system desired by the user can be easily realized.

  On the other hand, in such an image forming system 1, it is necessary to consider the adjustment of the temperature and humidity of the entire system. On the other hand, if a heater, a fan, or the like is provided for each peripheral device, the number of parts increases as a whole system, causing problems such as an increase in the cost of the image forming system 1. Therefore, the image forming system 1 is configured to provide a heater (heating element) 300 between the image forming apparatus 2 and the recording material supply apparatus 6.

  Next, the fixing device 23 will be described in detail with reference to FIGS. FIG. 2 is a cross-sectional view of the fixing device 23, and FIG. 3 is a view as seen from the axial direction of the fixing roller 101 of the fixing device 23. The fixing device 23 includes a fixing roller 101 that is a heating member and bearings 102 that are respectively fitted to both ends of the fixing roller 101 in the axial direction, and the fixing roller 101 is rotatably supported. A gear (not shown) is connected to one end of the fixing roller 101 in the axial direction, and the driving force from a motor separately installed on the gear is transmitted, whereby the fixing roller 101 is rotationally driven.

  A plurality of halogen lamps 105 a and 105 b that are heating sources are provided on the inner surface of the fixing roller 101, and a plurality of thermistors 103 a and 103 b that are temperature sensors are provided on the surface of the fixing roller 101. A plurality of thermostats 104a and 104b, which are temperature detecting means, are provided. Further, a pressure roller 106 slidably contacting the recording material is disposed at a position where the nip portion N is defined by opposing pressure contact with the lower portion of the fixing roller 101, and a bearing (not shown) that allows the pressure roller 106 to rotate is added. A shaft end of the pressure roller 106 is fitted. The bearing is supported by a pressure holding unit 107 for applying pressure to the surface of the fixing roller 101, and a compression spring 108 for applying a load is connected to the pressure holding unit 107.

  First, the fixing roller 101 will be described in detail. This fixing roller 101 is recorded on an aluminum cored bar having a total length of 346 mm and a low heat capacity, which is a length that can ensure a sufficient length even when a recording sheet having an outer diameter of 30 mm, 0.6 mm, and A3 width is passed. A release layer (for example, PTFE) for preventing the toner on the paper from being offset is formed. The release layer of this example is uniformly formed by applying and baking a composition obtained by blending PFA and PTFE to a thickness of 15 μm via a primer layer having a thickness of 7 μm.

  However, the material of the core metal of the fixing roller 101 is not limited to aluminum as long as the heat capacity of the halogen lamps 105a and 105b can be transferred in a relatively short time. For example, a metal such as stainless steel or iron having a low heat capacity may be used.

  If the core metal thickness of the fixing roller 101 is an aluminum core metal, the thickness can be reduced to 0.6 mm when the outer diameter is 30 mm. If the thickness is further reduced, when a load is applied to the fixing roller 101 to form the nip portion N, the recording material may be bent during paper passing, This is because an appropriate nip width cannot be formed. Further, if the thickness of the cored bar is increased, the warm-up time of the fixing device becomes longer, and the energy saving performance of the intended fixing device is deteriorated.

  The material of the release layer is not particularly limited as long as it is excellent in heat resistance and durability and has excellent release properties from the toner, such as PFA (a copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether) or PTFE (polytetra). Fluoro-based materials such as (fluoroethylene) may be used. The fixing roller 101 holds the recording material between the pressure roller 106 and the thermistors 103 a and 103 b are in contact with the position just before the nip portion N with the pressure roller 106.

  In the pressure roller 106, a silicone sponge rubber is covered as an elastic layer on a metal core, and a PFA tube as a release layer that is in sliding contact with the recording material is integrally formed on the surface of the silicone sponge rubber. The core metal is, for example, solid iron having an outer diameter of 12 mm, but is not limited to this, and may be a low heat capacity aluminum metal or the like. For the elastic layer, a silicone rubber having a heat resistance of 5.5 mm in thickness is used. Further, the release layer material may be any material that is excellent in heat resistance and durability and has excellent release properties from the toner, and may be a fluorine-based material such as PFA or PTFE.

  As the PFA tube used for the release layer of the pressure roller 106, it is more preferable to use a conductive tube containing a conductive agent such as carbon. The reason for this is that when an insulating PFA tube is used, the pressure roller 106 is charged to approximately −5 kV due to frictional charging with the recording paper and the fixing roller 101, and as a result, the same negative polarity is applied to the nip portion N. An electric field that repels the toner toward the fixing roller 101 acts, and causes an electrostatic offset (a phenomenon in which toner adheres to the fixing roller 101 electrostatically) with respect to the fixing roller 101.

In the present embodiment, in view of this point, by using a conductive PFA tube, charging of the pressure roller 106 is prevented and generation of electrostatic offset is suppressed. In this embodiment, a PFA tube having a volume resistance of 10 ⁵ Ωcm is used to ensure the antistatic effect.

  The thermistors 103a and 103b are in contact with the surface of the fixing roller 101. Based on the temperature detected on the surface of the fixing roller 101, the thermistors 103a and 103b control the power supply to the halogen lamps 105a and 105b to make the surface of the fixing roller 101 have a predetermined surface. Function to control the temperature.

  The halogen lamps 105a and 105b include a halogen lamp 105a for heating the central portion of the fixing roller 101 and 105b for heating both ends of the fixing roller 101, and are connected to the thermostat 104a by a lead wire 109a connected to the halogen lamp 105a. In addition, it is connected to a power source 110 installed outside the fixing device via a thermostat 104a. Similarly, the halogen lamp 105b is connected to the thermostat 104b via the connected lead wire 109b, and is further connected to the power source 110 installed outside the fixing device via the thermostat 104b. It is connected firmly so as not to occur.

  The halogen lamps 105a and 105b are fixed so as not to contact the inner surface of the fixing roller 101 in the fixing roller 101 by a lamp folder (not shown). The halogen lamp 105a can be turned on at 650W, and the halogen lamp 105b can be turned on at 570W.

  In the halogen lamps 105a and 105b, a tungsten filament is disposed as a light source in a quartz glass tube. When this filament is energized, the filament emits light, and the emitted light passes through the quartz glass tube and passes through the fixing roller 101. Heat the inner surface. At this time, since the filament needs to be kept at a high temperature, an inert heat insulating gas is sealed in the quartz glass tube.

  As the type of gas, nitrogen, argon, krypton, or the like is enclosed, and these gases are appropriately selected according to cost and performance. In terms of cost, nitrogen is the cheapest and krypton is the most expensive, but krypton has the highest thermal insulation and high filament luminous efficiency, and the lowest is nitrogen gas. The color temperature of the halogen lamps 105a and 105b can be increased by increasing the filament temperature according to the type of gas. As shown in FIG. 4, when the color temperature of the halogen lamps 105a and 105b is low, the spectral distribution shifts to the long wavelength side, and when the color temperature of the halogen lamps 105a and 105b is high, the spectral distribution peaks to the short wavelength side. Move.

  On the other hand, as shown in FIG. 5, the light transmittance of the quartz glass constituting the halogen lamps 105a and 105b is approximately 90% or more on the short wavelength side (2.5 μm or less), but the long wavelength (2.5 μm or more). ), The light transmittance decreases rapidly. Therefore, in order to make the light emitted from the filament reach the inner surface of the fixing roller 101 efficiently, the color temperature of the halogen lamps 105a and 105b may be increased. If the color temperature of the halogen lamps 105a and 105b is 2450K or higher, preferably 2500K or higher, light emitted from the filament can pass through the quartz glass.

  On the other hand, an endothermic paint that efficiently converts light from the halogen lamps 105a and 105b into heat and transfers heat to the fixing roller 101 is applied to the inner surface of the core of the fixing roller 101. The unfixed toner image on the recording material is fixed by the heat of the fixing roller 101 thus applied.

  The endothermic paint is selected from the group consisting of, for example, (I) a polyol having two or more hydroxyl groups, an aromatic diamine, and a secondary diamine having a structure in which all α-coordinated carbon atoms are branched. A solvent-free main agent (1) containing at least one compound, and a coating composition comprising a solvent-free curing agent (2) containing an aliphatic polyfunctional isocyanate, (II) showing absorption in the visible region of sunlight, From a pigment showing reflection in the infrared region and any one or more of a solvent-soluble acrylic resin, an acrylic emulsion resin, a urea resin, an epoxy resin, a solvent-soluble fluorine resin, and a fluorine emulsion resin Coating compositions containing a vehicle to be selected and optionally a white pigment are known.

  As specific endothermic paint products, for example, Okitsumo No. 8000 (Okitsumo Co., Ltd.), Tetzol 2751 (Nippon Paint Co., Ltd.), Sermo Black L1-500 (Tokyo Thermal Chemical Co., Ltd.) and the like are known. If these endothermic paints are applied, the light from the halogen lamps 105a and 105b disposed inside the fixing roller 101 can be efficiently converted into heat, and the warm-up time can be shortened compared to the case where there is no endothermic paint. .

  In order to investigate the endothermic properties of heat-resistant paints, the above-mentioned three kinds of heat-resistant paints are applied on an aluminum plate, and with a spectrophotometer UV-3600 (Shimadzu Corporation), a near infrared region of 2.5 μm and an infrared spectrophotometer The total light absorption rate of 5 μm and 10 μm in the infrared region was measured with a total of FTIR-8200PC (Shimadzu Corporation).

As a result, as shown in FIG. 6, the absorption rate in the vicinity of 10 μm was 90% for Sermo Black, 73.2% for Okitsumo, 75.8% for Tetzol, and 94% for Sermo Black at around 5 μm. On the other hand, in the vicinity of Okitsumo 64.2%, Tetzol 66.1%, and 2.5 μm, Serumo Black 93.1%, Okitsumo 60.7%, and Tetzol 63.4%. As the shift to the side increases, the difference in absorptance increases. Therefore, when the color temperature of the halogen lamps 105a and 105b increases, the absorption efficiency of Okitsumo and Tetzol deteriorates.
On the other hand, even in the vicinity of the absorption rate of 2.5 μm of Sermo Black L1-500, the absorption rate does not change and light can be absorbed efficiently.

  The fixing device 23 of the present invention is a device comprising a fixing roller 101 having an outer diameter of 30 mm and a pressure roller 106 having an outer diameter of 23 mm, and the nip width of the nip portion N between the fixing roller 101 and the pressure roller 106 facing each other. W is set to 3.2 mm (for example, when the fixing speed V is 225 mm / s, the nip passage time W / V is 0.014 s).

  In order to verify the effect of this example, the warm-up time and the power consumption when 30 sheets were continuously fed from the start of warm-up were measured. As a criterion for determining the effect of shortening the warm-up time, a warm-up time of 10 seconds or less was accepted. The reason for this is that when the warm-up time is long, it is necessary to preheat the fixing device at a constant temperature even during standby, so that the power consumption of the fixing device during warm-up and standby increases. Therefore, as a result of verification as a warm-up time that does not require preheating and does not affect the copy operation, the copy operation takes about 10 seconds. If the warm-up time is 10 seconds or less, the fuser is warmed up from room temperature. This is because it has been found that the copying operation can be completed without waiting time.

  Here, the normal copy operation means that when the time for placing a document to be copied on the document table is 0 second, the copy button is pressed, the document is read by the scanner, and each image forming process operates to form an image. In addition, the recording paper is fed from the paper feed tray and the image image is transferred to the transfer unit, and then the time until the recording paper enters the paper feeding unit of the fixing device.

  First, in order to verify the effect of shortening the warm-up time, in this embodiment, the inner surface coating of the fixing roller 101 and the color temperature of the halogen lamps 105a and 105b are changed, and the conditions under which the warm-up time is 10 seconds or less are examined. The results are summarized in FIG.

  As a result of comparing the inner surface coating (No.1, No.2, No.3), it was found that Serumo Black L1-500 has the fastest warm-up time and has an energy saving effect. Furthermore, the result of a comparative experiment (No. 3, No. 3) using the fixing roller 101 whose inner surface coating is Sermo Black L1-500 and changing the color temperature of the halogen lamps 105a and 105b from the conventional 2450K to 2500K of this embodiment. 6) It was confirmed that the warm-up time can be increased in 10 seconds or less, and the amount of electric power during the paper passing is reduced.

  When the inner surface coating of the fixing roller 101 is the same and the warm-up shortening rate before and after the color temperature change of the halogen lamps 105a and 105b is compared, Okitsumo (No.1, No.4) is 98.2%, Tetzol (No. No. 5) is 98.1% warm-up reduction rate, while Sermo Black (No. 3, No. 6) is 95.1% reduction rate, so that the halogen lamps 105a and 105b are reduced. The effect of the combination with the color temperature of was observed.

(Example 2)
In the above embodiment, the fixing device including the pair of fixing roller 101 and the pressure roller 106 is described. However, the fixing device includes a heating roller 113 including a heating source therein and a stretching member such as one or a plurality of rollers. The present invention can also be applied to a belt fixing device including the fixing belt 111 and the pressure member.

  A specific cross-sectional view of the belt fixing device is shown in FIG. The belt fixing device includes a heating roller 113, a fixing roller 112, an endless fixing belt 111, and a pressure roller 106. A plurality of thermistors 103a and 103b, which are temperature sensors, are arranged on the surface of the heating roller 113, and a plurality of thermostats 104a, 104b, which are abnormal temperature detection means, are arranged near the surface of the heating roller 113, respectively. A bearing that is rotatably supported is installed at the shaft end portion of 106. The bearing is supported by a pressure holding unit 107 for applying pressure to the surface of the fixing roller 112, and a compression spring 108 for applying a load is connected to the pressure holding unit 107.

  The fixing belt 111 is stretched between a fixing roller 112 that forms a nip portion N between a heating roller 113 including a plurality of halogen lamps 105 a and 105 b and a pressure roller 106. The fixing belt 111 is formed in an endless shape from a heat-resistant and flexible material such as polyimide, Ni belt, stainless steel belt, or the like.

  The inner surface of the heating roller 113 is coated with an endothermic paint so that the light from the halogen lamps 105a and 105b can be efficiently absorbed, like the fixing roller 101 of FIG. In addition, since the fixing belt 111 is in a state in which tension is applied between the heating roller 113 and the fixing roller 112, the bearing support member 114 that supports the bearing 102 of the heating roller 113 is in tension with the fixing frame 115. By pulling the bearing 102, tension is applied to the belt.

  According to this embodiment, the rotatable endless fixing belt 111 is brought into sliding contact with the heating roller 113, and the heat of the heating roller 113 is supplied to the fixing belt 111 to heat the fixing belt 111. The unfixed toner image on the recording paper can be fixed in a short time by the heat of the fixing belt 111.

(Example 3)
In order to secure a wide nip width between the fixing roller 112 and the pressure roller 106 in the second embodiment, it is preferable that the surface of a metal core bar is covered with a silicone sponge layer.

DESCRIPTION OF SYMBOLS 1 Image forming system 2 Image forming apparatus 3 Scanner 4 Automatic document conveying apparatus 5 Post-processing apparatus 6 Recording material supply apparatus 8 Relay conveying unit 10 Duplex conveying apparatus 23 Fixing apparatus 101 Fixing roller (heating member, roller)
103a Thermistor 103b Thermistor 104a Thermostat 104b Thermostat 105a Halogen lamp (heating source)
105b Halogen lamp (heating source)
106 Pressure roller 111 Fixing belt (belt)
112 Fixing roller 113 Heating roller (heating member, roller)
N Nip part

Claims (5)

A heating source is arranged inside a rotatable heating member that is in sliding contact with the recording material, and an endothermic paint that absorbs the wavelength emitted from the heating source and transfers heat to the heating member is formed on the inner surface of the heating member to transfer heat. A fixing device for fixing an unfixed toner image on a recording material by the heat of the heating member,
The color temperature of the light emitted from the heating source is set to 2450K or higher,
The fixing device according to claim 1, wherein the spectral characteristic of the endothermic paint has an absorptance of 90% or more for a wavelength of 2.5 μm or less.   The fixing device according to claim 1, wherein the warm-up time is 10 seconds or less.   The fixing device according to claim 1, wherein the heating member is a low heat capacity roller.   A heatable belt is brought into contact with the heating member, the heat of the heating member is supplied to the belt to heat the belt, and the unfixed toner image on the recording material is fixed by the heat of the belt. The fixing device described. An image forming apparatus comprising the fixing device according to claim 1.