Fixing apparatus and image forming apparatus

Abstract

When determining whether the heating unit has reached the target temperature, compared to not correcting the detection delay of the first temperature detection unit by using the actual temperature previously detected by the second temperature detection unit, which has higher responsiveness than the first temperature detection unit used in the actual machine, it is possible to determine early whether the heating unit has reached the target temperature even when the first temperature detection unit, which has relatively lower responsiveness, is used. [Solution] The system comprises a heating unit heated by a heating source, a first temperature detection unit that detects the temperature of the heating unit, and a determination unit that uses the actual temperature previously detected by a second temperature detection unit, which has higher responsiveness than the first temperature detection unit, to correct the detection delay of the first temperature detection unit and determine whether or not the heating unit has reached a target temperature.

Description

Technical Field

[0006] ,

[0001] This invention relates to a fixing device and an image forming apparatus.

Background Art

[0002] Conventionally, as technologies related to fixing devices, for example, those disclosed in Patent Document 1 and Patent Document 2 have already been proposed.

[0003] In Patent Document 1, when the rise time from room temperature to the fixable temperature of the heating roller is Th, the diameter of the heating roller is D cm, the maximum paper feed width of the heating roller is W cm, and the response time of the temperature sensor is Ts, it is configured such that 5 (seconds) ≤ Th ≤ 0.23 × DW (seconds) and 0.01Th ≤ Ts ≤ 0.08Th.

[0004] Patent Document 2 is configured to include first temperature detection means that abuts on a heating body and detects the temperature of the heating body, and second temperature detection means that exists in a nip region formed by pressing a heat-resistant film contact surface of a support and a pressure member, is on the downstream side in the heat-resistant film moving direction from the heating body, and is positioned in a non-contact relationship with the heating body.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] The objective of this invention is to enable early determination of whether the heating unit has reached the target temperature, even when using a first temperature detection unit with relatively lower responsiveness, compared to a case where the detection delay of the first temperature detection unit is not compensated for by using the actual temperature previously detected by a second temperature detection unit with higher responsiveness than the first temperature detection unit used in the actual device. [Means for solving the problem]

[0007] The invention described in claim 1 comprises a heating section heated by a heating source, A first temperature detection unit for detecting the temperature of the heating unit, A determination unit determines whether the heating unit has reached a target temperature by using the actual temperature previously detected by a second temperature detection unit, which has a higher response rate than the first temperature detection unit, to correct the detection delay of the first temperature detection unit, based on the temperature change of the heating unit at the start of heating. This is a fixing device equipped with [a specific feature].

[0008] The invention described in claim 2 is a fixing device according to claim 1, wherein the determination unit corrects the detection delay of the first temperature detection unit by changing the target temperature.

[0009] The invention described in claim 3 is a fixing device according to claim 2, wherein the determination unit determines whether or not the target temperature has been reached by subtracting the difference between the actual temperature detected by the second temperature detection unit and the temperature detected by the first temperature detection unit from the target temperature.

[0010] The invention described in claim 4 is a fixing device according to claim 1, wherein the determination unit corrects the detection delay of the first temperature detection unit by changing the detection result of the first temperature detection unit.

[0011] The invention described in claim 5 is a fixing device according to claim 4, wherein the determination unit determines whether or not the target temperature has been reached by adding the difference between the detection result of the first temperature detection unit and the actual temperature detected by the second temperature detection unit.

[0012] The invention described in claim 6 is a fixing device according to claim 1, wherein the first temperature detection unit comprises a non-contact type temperature sensor.

[0013] The invention described in claim 7 is the fixing device according to claim 1, wherein the second temperature sensing unit is a radiation thermometer.

[0014] The invention described in claim 8 is a fixing device according to claim 1, wherein the determination unit holds data that approximates the actual temperature previously detected by the second temperature detection unit with a straight line.

[0015] The invention described in claim 9 is a fixing device according to claim 1, wherein the determination unit determines whether the heating unit has reached a target temperature when the detection result of the first temperature detection unit is less than or equal to a predetermined threshold, and does not determine whether the heating unit has reached a target temperature when the detection result of the first temperature detection unit exceeds a predetermined threshold.

[0016] The invention described in claim 10 is an image forming means for forming an image on a recording medium, Fixing means for fixing the image onto the recording medium, Equipped with, The image forming apparatus uses the fixing device described in any one of claims 1 to 9 as the fixing means. [Effects of the Invention]

[0017] According to the invention described in claim 1, when determining whether the heating unit has reached the target temperature, it is possible to determine early whether the heating unit has reached the target temperature, even when a first temperature detection unit with relatively low responsiveness is used, compared to not correcting the detection delay of the first temperature detection unit by using the actual temperature previously detected by a second temperature detection unit with higher responsiveness than the first temperature detection unit used in the actual machine.

[0018] According to the invention described in claim 2, the determination unit can use the detection result of the first temperature detection unit as is, compared to when the target temperature is not changed.

[0019] According to the invention described in claim 3, the determination unit can early determine whether the target temperature has been reached by directly using the detection result of the first temperature detection unit, by correcting the detection delay of the first temperature detection unit by subtracting the difference between the actual temperature detected by the second temperature detection unit and the detected temperature of the first temperature detection unit from the target temperature.

[0020] According to the invention described in claim 4, compared with the case where the determination unit corrects the detection delay of the first temperature detection unit by changing the target temperature, there is no need to change the target temperature.

[0021] According to the invention described in claim 5, the determination unit can determine whether the target temperature has been reached by adding the difference between the actual temperature detected by the second temperature detection unit to the detection result of the first temperature detection unit.

[0022] According to the invention described in claim 6, compared with the case where the first temperature detection unit is composed of a radiation thermometer, the size of the device can be reduced and the cost can be lowered.

[0023] According to the invention described in claim 7, compared with the case where the second temperature detection unit is a non-contact temperature sensor, the responsiveness can be improved.

[0024] According to the invention described in claim 8, compared with the case where the determination unit holds all the actual temperatures previously detected by the second temperature detection unit as data, the amount of data can be reduced.

[0025] According to the invention described in claim 9, compared with the case where the determination unit determines whether the heating unit has reached the target temperature when the detection result of the first temperature detection unit exceeds a predetermined threshold value, it is possible to accurately determine whether the target temperature has been reached.

[0026] According to the invention described in claim 10, even when employing a first temperature sensing unit which has relatively lower responsiveness compared to the case where the fixing device described in any of claims 1 to 9 is not used as the fixing means, it is possible to quickly determine whether or not the heating unit has reached the target temperature. [Brief explanation of the drawing]

[0027] [Figure 1] This is an overall configuration diagram showing an image forming apparatus to which the fixing device according to Embodiment 1 of this invention is applied. [Figure 2] This is a block diagram showing a control device for an image forming apparatus to which the fixing device according to Embodiment 1 of this invention is applied. [Figure 3] This is a cross-sectional view showing a fixing device according to Embodiment 1 of the present invention. [Figure 4] This is a perspective view diagram showing a fixing device according to Embodiment 1 of the present invention. [Figure 5] This is a side view taken from the direction of the arrow in Figure 4. [Figure 6] This chart shows the advantages and disadvantages of NC sensors and infrared thermometers. [Figure 7] This is an overall configuration diagram showing an offline bench of an image forming apparatus to which the fixing device according to Embodiment 1 of this invention is applied. [Figure 8] This graph shows the results of detecting the surface temperature of the heating roll using an infrared thermometer. [Figure 9] This is a flowchart showing the operation of an image forming apparatus to which the fixing device according to Embodiment 1 of this invention is applied. [Figure 10] This graph shows the change in the surface temperature of the heating roll in accordance with the operation of an image forming apparatus to which the fixing device according to Embodiment 1 of this invention is applied. [Modes for carrying out the invention]

[0028] Embodiments of this invention will be described below with reference to the drawings.

[0029] [Embodiment 1] Figure 1 shows a schematic overview of an image forming apparatus to which the fixing device according to Embodiment 1 is applied. In the figure, arrow X indicates the width direction along the horizontal, Y indicates the depth direction along the horizontal, and Z indicates the vertical direction.

[0030] <Overall configuration of the image forming apparatus> The image forming apparatus 1 is configured, for example, as a color printer. As shown in Figure 1, this image forming apparatus 1 includes a plurality of image forming devices 10, an intermediate transfer device 20, a paper feed device 50, a fixing device 40, etc. The image forming devices 10 form toner images that are developed with toner, which constitutes the developer. The intermediate transfer device 20 holds the toner images formed by each image forming device 10 and transports them to a secondary transfer position T2 where they are ultimately transferred to a recording paper 5, which is an example of a recording medium. The paper feed device 50 receives and transports the required amount of recording paper 5 to be supplied to the secondary transfer position T2 of the intermediate transfer device 20. The fixing device 40 fixes the toner images on the recording paper 5 that have been transferred by the intermediate transfer device 20. Here, the plurality of image forming devices 10 and the intermediate transfer device 20 constitute an image forming means for forming an image on the recording paper 5. Reference numeral 1a indicates the main body of the apparatus, which is formed by support structural members, outer covers, etc.

[0031] The imaging device 10 consists of four imaging devices 10Y, 10M, 10C, and 10K, each dedicated to forming toner images of four colors: yellow (Y), magenta (M), cyan (C), and black (K). These four imaging devices 10 (Y, M, C, K) are arranged in a single row within the internal space of the device body 1a, tilted with respect to the horizontal direction X.

[0032] Each imaging device 10 (Y, M, C, K) is equipped with a photoreceptor drum 11 as an example of a rotating image holding means, as shown in Figure 1. Around this photoreceptor drum 11 are a charging device 12, an exposure device 13, a developing device 14, a primary transfer device 15, a drum cleaning device 16, etc. The charging device 12 charges the image-forming surface (image-holding surface) of the photoreceptor drum 11 to the required potential. The exposure device 13 irradiates the charged surface of the photoreceptor drum 11 with light based on image information (signals) to form electrostatic latent images (for each color) with potential differences. The developing device 14 develops these electrostatic latent images with toners of the corresponding color (Y, M, C, K) to form toner images. The primary transfer device 15 transfers each of these toner images to an intermediate transfer device 20. The drum cleaning device 16 cleans the image-holding surface of the photoreceptor drum 11 by removing any toner or other deposits that remain after the primary transfer.

[0033] The photoreceptor drum 11 has an image-holding surface formed on the circumferential surface of a cylindrical or columnar substrate that is grounded, and the photoreceptor drum 11 has a photoconductive layer (photosensitive layer) made of a photosensitive material. The photoreceptor drum 11 is supported so as to rotate in the direction indicated by arrow A by a driving force transmitted from a drive device (not shown).

[0034] The charging device 12 consists of a contact-type charging roll 120 positioned in contact with the photoreceptor drum 11. A charging voltage is supplied to the charging roll 120. If the developing device 14 performs reverse development, the charging voltage supplied is a voltage or current with the same polarity as the charging polarity of the toner supplied from the developing device 14. A cleaning roll 121 is positioned in contact with the back side of the charging roll 120 to clean the surface of the charging roll 120.

[0035] The exposure apparatus 13 consists of an LED print head and the like, which irradiates the photoreceptor drum 11 with light corresponding to image information using multiple LEDs (Light Emitting Diodes) arranged along the axial direction of the photoreceptor drum 11 to form an electrostatic latent image. When latent image formation is in progress, the exposure apparatus 13 receives image information (signals) input to the image forming apparatus 1 by any means.

[0036] Each developing device 14, as shown in Figure 1, consists of a housing 140, a developing roll 141, agitation and conveying members 142 and 143, and a layer thickness regulating member 144. The housing 140 has an opening and a developing agent storage chamber. The developing roll 141 holds the developing agent and conveys it to the developing area facing the photoreceptor drum 11. The agitation and conveying members 142 and 143 consist of screw augers, etc., that convey the developing agent while agitating it as it passes through the developing roll 141. The layer thickness regulating member 144 regulates the amount of developing agent (layer thickness) held by the developing roll 141. In this developing device 14, a developing voltage is supplied between the developing roll 141 and the photoreceptor drum 11 from a power supply unit (not shown). The developing roll 141 and the agitation and conveying members 142 and 143 are rotated in the required direction by driving force transmitted from a drive unit (not shown). Furthermore, the developers used for the four colors (Y, M, C, K) are two-component developers containing non-magnetic toner and magnetic carriers.

[0037] The primary transfer device 15 is a contact-type transfer device equipped with a primary transfer roll to which a primary transfer voltage is supplied. At the primary transfer position T1, the primary transfer device 15 contacts the circumferential surface of the photoreceptor drum 11 via an intermediate transfer belt 21 and rotates. As the primary transfer voltage, a DC voltage exhibiting the opposite polarity to the charging polarity of the toner is supplied from a power supply device (not shown).

[0038] The drum cleaning device 16 consists of a container-shaped body 160, a cleaning blade 161, and a delivery member 162. The cleaning blade 161 is positioned at the opening of the container-shaped body 160 to remove residual toner and other deposits for cleaning. The delivery member 162 consists of a screw auger or the like that collects the toner and other deposits removed by the cleaning blade 161 and transports them to a collection system (not shown).

[0039] The intermediate transfer device 20 is positioned above each imaging device 10 (Y, M, C, K) along the vertical Z direction. This intermediate transfer device 20 mainly consists of an intermediate transfer belt 21, a plurality of belt support rolls 22-25, a secondary transfer device 30, and a belt cleaning device 26. The intermediate transfer belt 21 moves in a circular motion in the direction indicated by arrow B, passing through the primary transfer position T1, which is between the photoreceptor drum 11 and the primary transfer device 15. The plurality of belt support rolls 22-25 support the intermediate transfer belt 21 from its inner circumference, holding it in a desired state so that it can move in a circular motion. The secondary transfer device 30 is positioned on the outer circumferential surface (image holding surface) side of the intermediate transfer belt 21, which is supported by the belt support rolls 25, and transfers the toner image on the intermediate transfer belt 21 to the recording paper 5. The belt cleaning device 26 cleans the intermediate transfer belt 21 by removing any toner, paper dust, and other deposits that remain and adhere to the outer circumferential surface after passing through the secondary transfer device 30.

[0040] The intermediate transfer belt 21 is an endless belt made of a material in which a resistance modifier such as carbon black is dispersed in a synthetic resin such as polyimide resin or polyamide resin. The belt support roll 22 is configured as a drive roll. The belt support roll 23 is configured as a surface-setting roll that holds the running position of the intermediate transfer belt 21. The belt support roll 24 is configured as a sensor roll on which a sensor (not shown) is opposed. The belt support roll 25 is configured as a backup roll for secondary transfer.

[0041] The secondary transfer device 30 includes a secondary transfer roll 31 that rotates at the secondary transfer position T2, which is the outer circumferential surface portion of the intermediate transfer belt 21 supported by the belt support roll 25 in the intermediate transfer device 20. A DC voltage with opposite or same polarity as the charge polarity of the toner is supplied to the secondary transfer roll 31 or the belt support roll 25 of the intermediate transfer device 20 as the secondary transfer voltage.

[0042] The fixing device 40 is composed of a heating roll 41 and a pressure belt 42, etc. The heating roll 41 is heated by a heating source so that its surface temperature is maintained at a predetermined temperature. The pressure belt 42 rotates in contact with the heating roll 41 at the required pressure. In this fixing device 40, the contact area where the heating roll 41 and the pressure belt 42 come into contact becomes the fixing processing unit N that performs the required fixing process (heating and pressurizing). In this embodiment 1, the heating roll 41 is used as an example of a heating rotating body, and the pressure belt 42 is used as an example of a pressurizing rotating body. However, it is not limited to this, and the heating rotating body and the pressurizing rotating body may be in the form of a roll or a belt. The fixing device 40 will be described in detail later.

[0043] The paper feeder 50 is positioned below the image creation device 10 (Y, M, C, K) along the vertical Z direction. This paper feeder 50 mainly consists of a paper container 52 and a paper feeder 53. The paper container 52 stores recording paper 5 of the desired size and type, stacked on a stacking plate 51. The paper feeder 53 feeds the recording paper 5 one sheet at a time from the paper container 52. The paper container 52 is mounted so that it can be pulled out, for example, from the front side (the side that the user faces when operating) of the device body 1a.

[0044] Examples of recording paper 5 include thin paper such as plain paper or tracing paper used in electrophotographic copiers and printers, or OHP sheets made of a transparent film-like medium made of synthetic resin (such as PET). To further improve the smoothness of the image surface after fixing, it is preferable that the surface of the recording paper 5 be as smooth as possible. For this reason, so-called thick paper with a relatively large basis weight, such as coated paper made by coating the surface of plain paper with resin, or art paper for printing, can also be suitably used as recording paper 5.

[0045] A paper feed transport path 57 is provided between the paper feed device 50 and the secondary transfer device 30. The paper feed transport path 57 consists of one (or more) pairs of paper transport rolls 54 and transport guide members 55, 56 that transport the recording paper 5 fed from the paper feed device 50 to the secondary transfer position T2. ​​The pair of paper transport rolls 54 positioned immediately before the secondary transfer position T2 in the paper feed transport path 57 is configured, for example, as a register roll to adjust the transport timing of the recording paper 5.

[0046] Furthermore, a paper transport path 59 is provided between the secondary transfer device 30 and the fixing device 40. The paper transport path 59 consists of transport guide members 58 and the like that transport the recording paper 5 fed out from the secondary transfer device 30 to the fixing device 40.

[0047] A discharge transport path 65 is provided downstream of the fuser 40. The discharge transport path 65 includes a pair of paper transport rolls 61 and 62, as well as transport guide materials 63, 64, etc., for discharging the recording paper 5, on which the toner image has been fixed by the fuser 40, to the paper discharge section 60 located at the top of the main body 1a of the device.

[0048] In Figure 1, reference numeral 100 denotes a control device as an example of a control means that comprehensively controls the operation of the image forming apparatus 1.

[0049] As shown in Figure 2, the control device 100 includes a control panel 101 and a control unit 102 that also functions as an example of a determination unit for the fixing device 40. The control panel 101 is provided with an input unit 111 for the user to input desired image formation conditions, and a display unit 112 that displays the image formation conditions and the status of the image forming device entered in the input unit 111. The control unit 102 is configured to include a CPU (Central Processing Unit) 121, ROM (Read Only Memory) 122, RAM (Random Access Memory) 123, a bus (not shown) connecting the CPU 121, ROM 122, etc., and a communication interface 124 for communication with the outside. The CPU 121 controls the necessary image formation operations, including temperature control and driving of the fixing device 40, based on a program stored in the ROM 122, etc.

[0050] <Basic operation of an image forming apparatus> The following describes the basic image forming operation of the image forming apparatus 1.

[0051] This section describes the image formation operation when forming a full-color image by combining four toner images (Y, M, C, K) using the four imaging devices 10 (Y, M, C, K). The image formation operation is basically the same when forming an image by combining single-color or multi-color toner images using one or more of the four imaging devices 10 (Y, M, C, K).

[0052] When the image forming apparatus 1 receives command information requesting an image forming operation (printing) from the control panel 101 or the like, the control device 100 controls the four image forming devices 10 (Y, M, C, K), the intermediate transfer device 20, the secondary transfer device 30, the fixing device 40, etc. to start up.

[0053] Then, in each imaging apparatus 10 (Y, M, C, K), each photoreceptor drum 11 first rotates in the direction indicated by arrow A. Each charging apparatus 12 charges the surface of each photoreceptor drum 11 to the required polarity (negative polarity in Embodiment 1) and potential. Subsequently, the exposure apparatus 13 irradiates the charged surface of the photoreceptor drum 11 with light emitted based on the image signal obtained by converting the image information input to the image forming apparatus 1 into each color component (Y, M, C, K). Electrostatic latent images of each color component, each composed of a required potential difference, are formed on the surface of the photoreceptor drum 11.

[0054] Next, each developing device 14 supplies toner of the corresponding color (Y, M, C, K), which is charged with the required polarity (negative polarity), to the electrostatic latent image of each color component formed on the photoreceptor drum 11, and electrostatically deposits it to develop the image. Through this development, the electrostatic latent image of each color component formed on each photoreceptor drum 11 is revealed as four toner images of the corresponding colors (Y, M, C, K), which have been developed with the toner of the corresponding color.

[0055] Next, the toner images of each color formed on the photoreceptor drum 11 of each imaging device 10 (Y, M, C, K) are transported to the primary transfer position T1. Then, the primary transfer device 15 performs a primary transfer, sequentially overlapping the toner images of each color onto the intermediate transfer belt 21 of the intermediate transfer device 20, which rotates in the direction indicated by arrow B.

[0056] Furthermore, in each imaging apparatus 10 (Y, M, C, K) where the primary transfer has been completed, the drum cleaning device 16 cleans the surface of the photoreceptor drum 11 by scraping off any adhering material. This prepares each imaging apparatus 10 (Y, M, C, K) for the next imaging operation.

[0057] Next, the intermediate transfer device 20 holds the toner image transferred in the first stage by the rotation of the intermediate transfer belt 21 and transports it to the secondary transfer position T2. ​​Meanwhile, the paper feed device 50 feeds the required recording paper 5 into the paper feed transport path 57 in accordance with the image formation operation. In the paper feed transport path 57, a pair of paper transport rolls 54 acting as registration rolls feeds and supplies the recording paper 5 to the secondary transfer position T2 in accordance with the transfer timing.

[0058] At the secondary transfer position T2, the secondary transfer roll 31 transfers the toner image on the intermediate transfer belt 21 onto the recording paper 5 in one go. After the secondary transfer is completed, the belt cleaning device 26 in the intermediate transfer device 20 cleans the surface of the intermediate transfer belt 21 by removing any toner or other deposits remaining after the secondary transfer.

[0059] Next, the recording paper 5, on which the toner image has been secondarily transferred, is peeled off from the intermediate transfer belt 21 and the secondary transfer roll 31 and then transported along the paper transport path 59 to the fuser device 40. In the fuser device 40, the recording paper 5 after secondary transfer is introduced and passed through the fuser processing section N between the rotating heating roll 41 and the pressure belt 42. This performs the necessary fuser processing (heating and pressurizing) to fix the unfixed toner image to the recording paper 5. After the fuser is complete, the recording paper 5 is discharged via the discharge transport path 65 by a pair of paper discharge rolls 62 to the paper discharge section 60 located at the top of the device body 1a.

[0060] Through the above process, a full-color image is output, formed by combining toner images consisting of four toner colors (Y, M, C, K).

[0061] <Configuration of the fixing device> The fixing device 40 is a so-called free-belt nip fuser (FBNF) type fixing device. As shown in Figures 3 and 4, the fixing device 40 is broadly composed of a heating roll 41 as an example of a heating section, a pressure belt 42, a pressure member 43, a holding member 44, a sliding sheet 45, a felt member 49, etc. Note that in Figures 3 and 4, the housing of the fixing device 40 that covers the outer circumference of the heating roll 41 and the pressure belt 42 is omitted from the illustration. The pressure member 43 is positioned inside the pressure belt 42 and presses the pressure belt 42 against the surface of the heating roll 41. The holding member 44 holds the pressure member 43. The sliding sheet 45 is interposed between the pressure belt 42 and the pressure member 43 to reduce sliding resistance. The felt member 49 holds the lubricant applied to the inner circumferential surface of the pressure belt 42.

[0062] As shown in Figure 4, the pressure belt 42 is rotatably arranged inside, for example, a housing (not shown) of the fixing device 40. The pressure belt 42 is biased in a direction toward pressing against the heating roll 41 together with the holding member 44, etc., by a coil spring 70, which is an example of a biasing means, and forms a fixing section N between the heating roll 41 and the pressure belt 42.

[0063] As shown in Figure 3, the heating roll 41 has a core metal 411, an elastic layer 412, and a release layer 413. The core metal 411 is a cylindrical member made of metal such as stainless steel, aluminum, or iron (thin-walled high-tensile steel pipe). The elastic layer 412 is made of an elastic material such as heat-resistant silicone rubber or fluororubber that is coated on the outer circumference of the core metal 411. The release layer 413 is made of polytetrafluoroethylene (PTFE) or perfluoroalkoxyalkane (PFA) that is thinly coated on the surface of the elastic layer 412. A halogen lamp 414 is placed inside the heating roll 41 as an example of a heat source. The heating roll 41 is rotated along the direction of arrow C by a drive device (not shown). In the example in Figure 3, the elastic layer 412 is shown as relatively thick, but in order to keep the heat capacity of the heating roll 41 relatively small, it is desirable to form the elastic layer 412 as thin as possible.

[0064] The halogen lamp 414 consists of, for example, a first halogen lamp 414a and a second halogen lamp 414b. The first halogen lamp 414a heats the central part of the heating roll 41 along its longitudinal direction for a required width, for example, an area along the short side of an A4-sized recording sheet 5. The second halogen lamp 414b heats the areas at both ends of the heating roll 41 along its longitudinal direction. However, it is not necessary to provide multiple halogen lamps 414; the heating roll 41 may be equipped with only a single halogen lamp that heats the entire area along its longitudinal direction.

[0065] The heating roll 41 has its surface temperature detected by a first temperature sensor 130, which is an example of a first temperature detection unit. As the first temperature sensor 130, for example, an NC (non-contact) temperature sensor consisting of a thermistor is used. The first temperature sensor 130 is positioned in a non-contact manner at a required distance from the surface of the heating roll 41. The first temperature sensor 130 consisting of a thermistor or the like does not have a relatively high response rate, but it is small and relatively inexpensive, making it suitable for use in actual machines.

[0066] As shown in Figure 5, the first temperature sensor 130 is positioned in the housing 400 of the fixing device 40 in a non-contact manner near the central part along the longitudinal direction of the heating roll 41, with a required gap between it and the surface of the heating roll 41. Figure 5 is a side view of the housing 400 of the fixing device 40 as seen from the direction of the arrow in Figure 4. In Figure 5, reference numeral 131 denotes the first thermostat positioned in the central part along the longitudinal direction of the heating roll 41, and reference numeral 132 denotes the second thermostat positioned at one end along the longitudinal direction of the heating roll 41. The first thermostat 131 automatically shuts off the power supply to the first halogen lamp 414a when the surface temperature at the central part of the heating roll 41 exceeds a specified upper limit. The second thermostat 132 automatically shuts off the power supply to the second halogen lamp 414b when the surface temperature at the end of the heating roll 41 exceeds a specified upper limit.

[0067] As shown in Figure 2, the heating roll 41 is heated so that its surface maintains a required fixing temperature (for example, around 140-150°C) by controlling the on / off state of the halogen lamp 414 based on the detection result of the first temperature sensor 130 using an on / off control circuit 125 consisting of a triac or the like provided in the control unit 102.

[0068] On the other hand, the pressure belt 42 is configured as a thin-walled cylindrical endless belt, as shown in Figures 3 and 4. The pressure belt 42 comprises a base layer, an elastic layer covered on the surface of the base layer, and a release layer covered on the surface of the elastic layer.

[0069] Inside the pressure belt 42, a pressure member 43 is arranged as shown in Figure 3. The pressure member 43 comprises a pressure pad 46 that presses the pressure belt 42 toward the surface of the heating roll 41, and a support member 47 that is harder than the pressure pad 46 and supports the pressure pad 46.

[0070] The support member 47 is provided with a mounting portion 471 on the side opposite to the heating roll 41 for attaching the support member 47 to the holding member 44. The mounting portion 471 of the support member 47 clamps the horizontal plate portion 441a of the holding plate 441, which is formed in an L-shape in cross-section of the holding member 44, with a first clamping plate portion 471a and a second clamping plate portion 471b. The mounting portion 471 of the support member 47 is then attached to the holding member 44 in a fixed state by means such as adhesive, as necessary.

[0071] Furthermore, the mounting portion 471 of the support member 47 is provided with multiple locking projections 472 along its longitudinal direction for engaging the tip of the sliding sheet 45.

[0072] As shown in Figure 3, the holding member 44 is a member that holds the pressure pad 46 and the support member 47. The pressure pad 46 and the support member 47 receive a reaction force from the heating roll 41 by being pressed against the surface of the heating roll 41. The holding member 44 has high rigidity so as not to bend or deform along its longitudinal direction in response to the reaction force received by the pressure pad 46 and the support member 47 from the heating roll 41. The holding member 44 is composed of a holding plate 441 and a holding body 442. The holding plate 441 is formed to have a roughly L-shaped cross-section by drawing or bending of a metal such as aluminum or stainless steel. The holding body 442 is made of a heat-resistant synthetic resin or the like and is fixed to the holding plate 441 along its longitudinal direction.

[0073] A felt member 49 is attached to the vertical plate portion 441b of the retaining plate 441 by means of adhesion or bonding via double-sided tape or the like (not shown). The felt member 49 is pre-impregnated with a lubricant, for example, to be supplied applied to the inner circumferential surface of the pressure belt 42. As the lubricant, for example, an amino-modified silicone oil is used.

[0074] The sliding sheet 45 consists of an elongated, rectangular sheet. As an example of the sliding sheet 45, one can be used that has a base layer made of a fluororesin such as polytetrafluoroethylene (PTFE) and a structure made of a woven or knitted fabric made of aramid fibers or the like laminated on the surface or both sides of the base layer.

[0075] As shown in Figures 3 and 4, the pressure belt 42 is guided by guide members 48 so that both ends along its longitudinal direction can move in a circular motion. The guide members 48 consist of substantially disc-shaped members with a front surface, provided at both ends along the longitudinal direction of the holding plate 441. The inner surface of the guide members 48 is provided such that the guide portion for the circulating movement of the pressure belt 42 protrudes inward along its longitudinal direction.

[0076] Incidentally, in the fixing device 40 configured as described above, as shown in Figure 2, when the device receives command information requesting an image forming operation (print) from the control panel 101 or the like, and starts the image forming operation, the heating roll 41 is heated by energizing the halogen lamps 414a and 414b, which serve as heating sources. At that time, the surface temperature of the heating roll 41 is detected by the first temperature sensor 130. The control unit 102 of the control device 100 determines whether the surface temperature of the heating roll 41 has reached the target weight-up temperature, according to the surface temperature of the heating roll 41 detected by the first temperature sensor 130. When the control unit 102 detects that the surface temperature of the heating roll 41 has reached the weight-up temperature, it changes the status to the print status and rotates the photoreceptor drum 11 of each imaging device 10 (Y, M, C, K) to start the image forming operation.

[0077] In this case, the fixing device 40 employs an NC sensor with relatively low responsiveness as the first temperature sensor 130. Therefore, when the fixing device 40 determines whether the surface temperature of the heating roll 41 has reached the target temperature, a detection delay inevitably occurs in which the surface temperature of the heating roll 41 is detected as lower than the actual surface temperature.

[0078] As a result, in the fixing device 40 prior to the application of this embodiment 1, even though the surface temperature of the heating roll 41 has already reached the target temperature, the weight-up temperature, it is determined that the surface temperature of the heating roll 41 has not yet reached the target temperature. The control unit 102 then determines that the weight-up temperature has been reached only when the first temperature sensor 130 actually detects the target temperature as the surface temperature of the heating roll 41. Therefore, the image forming apparatus 1 equipped with the fixing device 40 has a longer weight-up time due to the detection delay of the first temperature sensor 130. As a result, the printer had a technical problem in that it could not achieve internationally defined environmental standard values ​​for ultrafine particle dust (UFP) emissions, power consumption, or startup waiting time.

[0079] Therefore, in this embodiment, the system is configured to include a determination unit that uses the actual temperature previously detected by a second temperature detection unit, which has higher responsiveness than the first temperature detection unit, to correct the detection delay of the first temperature detection unit and determine whether or not the heating unit has reached the target temperature.

[0080] In other words, in the image forming apparatus 1 according to this embodiment 1, an offline bench equipped with a fixing device 40 to be mounted on the actual machine is manufactured, as shown in Figure 7. However, in the fixing device 40 of the offline bench, instead of the first temperature sensor 130 consisting of an NC sensor used in the actual machine as a temperature detection unit for detecting the surface temperature of the heating roll 41, a radiation thermometer 135 is used as an example of a second temperature detection unit with higher responsiveness than the temperature sensor consisting of the NC sensor.

[0081] The radiation thermometer 135 detects temperature by measuring the amount of infrared energy emitted from an object. As shown in Figure 6, the radiation thermometer 135 has a higher response rate and can detect the temperature of an object in a very short time compared to the first temperature sensor 130, which consists of an NC sensor. However, the radiation thermometer 135 is relatively large and expensive, making it unsuitable for use in the actual image forming apparatus 1.

[0082] In the image forming apparatus 1 according to this embodiment 1, as shown in Figure 7, an infrared thermometer 135 is installed in the same position as the first temperature sensor 130, but in place of the first temperature sensor 130, in an offline bench that includes a fixing device 40 configured in the same way as the actual machine. Note that the offline bench does not necessarily have to include the entire image forming apparatus 1; an offline bench consisting of only the fixing device 40 may be used as long as it can reproduce the state at the start of heating of the heating roll 41 of the fixing device 40.

[0083] Then, a bench model of the image forming apparatus 1, consisting of a fixing device 40 equipped with a radiation thermometer 135, or a bench model of the fixing device 40 equipped with a radiation thermometer 135, was set up in a normal temperature and humidity environment, which is the same environment as an actual office or similar setting.

[0084] Subsequently, under the same conditions as at the start of the image formation operation, power was supplied to the halogen lamps 414a and 414b of the heating roll 41 of the fixing device 40, and heating of the heating roll 41 was started. The change in the surface temperature of the heating roll 41 at the start of heating was detected (measured) by the radiation thermometer 135.

[0085] Figure 8 is a graph showing the results of detecting (measuring) the surface temperature of the heating roll 41 at the start of heating using the radiation thermometer 135 and the first temperature sensor 130.

[0086] Here, the surface temperature of the heating roll 41 at the start of heating, as detected by the radiation thermometer 135 which has a higher response rate than the first temperature sensor 130, is referred to as the "actual temperature." Furthermore, the curve or straight line showing the temperature change during the rise time, as detected by the radiation thermometer 135 at the start of heating, is referred to as the "actual temperature line."

[0087] As is clear from Figure 8, the surface temperature of the heating roll 41 at the start of heating was detected in advance by the radiation thermometer 135 and it can be seen that it rises sharply in an almost linear fashion at the same time as the start of heating, which is when the halogen lamps 414a and 414b are energized.

[0088] On the other hand, the results of detecting the surface temperature of the heating roll 41 at the start of heating with the first temperature sensor 130 show that it rises later than the start of heating, which is when power is supplied to the halogen lamps 414a and 414b, compared to the results of the radiation thermometer 135. In addition, the slope of the straight line rising from the result detected by the first temperature sensor 130 is smaller compared to that of the radiation thermometer 135.

[0089] Then, when the control unit 102 detects that the surface temperature of the heating roll 41 has reached a predetermined target temperature, which is the weight-up temperature, it switches to the print status and performs the necessary image forming operations, such as starting the rotation of the heating roll 41.

[0090] As a result, the surface temperature of the heating roll 41 initially decreases due to the start of rotation of the heating roll 41, and then rises while the amplitude of the vertical vibration (fluctuation) gradually decreases.

[0091] Therefore, although the surface temperature of the heating roll 41 tends to decrease slightly as the fixing operation begins, the power supply to the halogen lamps 414a and 414b is controlled by the power supply control circuit 125, maintaining a temperature approximately equal to the required fixing temperature.

[0092] Incidentally, the detection results of the surface temperature of the heating roll 41 by the radiation thermometer 135 and the first temperature sensor 130 at the start of heating should be the same, or reproducible, if the detection conditions, i.e., the image forming apparatus 1 and the fixing apparatus 40 are the same and the environmental conditions (ambient temperature) are the same. In other words, at the same ambient temperature, the amount of heat generated when power is supplied to the halogen lamps 414a and 414b of the heating roll 41 is constant, and the heat capacity of the fixing apparatus 40 including the heating roll 41, and furthermore, the image forming apparatus 1, is constant. Therefore, at the same ambient temperature, the change in the surface temperature of the heating roll 41 when power is supplied to the halogen lamps 414a and 414b of the heating roll 41 is reproducible whether detected by the radiation thermometer 135 or by the first temperature sensor 130.

[0093] In other words, when the image forming apparatus 1 and the fixing apparatus 40 are on the same offline bench, the results obtained by detecting the surface temperature of the heating roll 41 at the start of heating using the radiation thermometer 135 can always be considered to have the same relationship as the results obtained by detecting the surface temperature of the heating roll 41 in the actual machine using the first temperature sensor 130, as shown in Figure 8.

[0094] Furthermore, according to the inventors' experimental results, it has been confirmed that if the ambient temperature is below a predetermined upper limit, the result of detecting the surface temperature of the heating roll 41 at the start of heating will only differ in the initial temperature, and the gradient of the actual temperature will not change. Here, the case where the ambient temperature exceeds the predetermined upper limit means, for example, that not enough time has elapsed since the completion of a series of image forming operations in the image forming apparatus 1, and the heating roll 41 and pressure belt 42 are still being heated.

[0095] Therefore, in the fixing device 40 according to this embodiment 1, the actual temperature of the heating roll 41 at the start of heating is the result of the fixing device 40 detecting in advance with a radiation thermometer 135 in the same bench model.

[0096] The actual temperature and temperature curve, which represent the temperature change of the heating roll 41 at the start of heating as detected in advance by the radiation thermometer 135, are pre-stored as data in the ROM 122. As shown in Figure 8, this actual temperature and temperature curve may be stored as a table of data for time and temperature. Alternatively, as shown in the same figure, the temperature curve may be approximated by a straight line L, and the data consisting of a mathematical formula representing this straight line L may be pre-stored in the ROM 122. In this embodiment 1, data approximated by a straight line L is used as the temperature curve.

[0097] Then, when heating of the heating roll 41 begins, the control unit 102 reads the actual temperature curve, which is the temperature change of the heating roll 41 at the start of heating, as data stored in the ROM 122. The control unit 102 is configured to determine whether or not the heating roll 41 has reached the target temperature, the weight-up temperature, by correcting the detection result of the first temperature sensor 130, which detects the surface temperature of the heating roll 41 at the start of heating, using the read data of the actual temperature and the actual temperature curve, which is the temperature change of the heating roll 41.

[0098] When the control unit 102 determines whether the heating roll 41 has reached the target weight-up temperature, it corrects the target weight-up temperature of the heating roll 41 using the actual temperature line data of the heating roll 41.

[0099] To explain further, as shown in Figure 8, the control unit 102 is configured to correct the target temperature by subtracting the difference between the actual temperature and actual temperature line data of the heating roll 41 and the detection result of the first temperature sensor 130 from the weight-up temperature, which is the target temperature of the heating roll 41.

[0100] <Operation of the fixing device> In the fixing device 40 according to this embodiment 1, when determining whether the heating unit has reached the target temperature, it is possible to determine early whether the heating unit has reached the target temperature, even when a first temperature detection unit with relatively lower responsiveness is used, compared to when the detection delay of the first temperature detection unit is not corrected using the actual temperature previously detected by a second temperature detection unit with higher responsiveness than the first temperature detection unit used in the actual machine.

[0101] In other words, in the image forming apparatus 1 to which the fixing device 40 according to this embodiment 1 is applied, as shown in Figure 1, when command information requesting an image forming operation (print) is received, the control device 100 controls the four image forming devices 10 (Y, M, C, K), the intermediate transfer device 20, the secondary transfer device 30, the fixing device 40, etc. to start up.

[0102] Then, in the fixing device 40 according to this embodiment 1, as shown in Figure 2, power is supplied to the halogen lamps 414a and 414b of the heating roll 41, and the heating roll 41 is heated by the halogen lamps 414a and 414b.

[0103] First, in the fixing device 40, as shown in Figure 9, the surface temperature Main_NC_T of the heating roll 41 at the start of heating is detected by the first temperature sensor 130, which consists of an NC sensor. The control unit 102 then determines whether this detected temperature Main_NC_T is below the start determination temperature (step 101). Here, the start determination temperature is set to, for example, a temperature higher than normal room temperature, around 40-50°C. This start determination temperature is used to determine whether the control operation according to this embodiment 1 is applicable. If the control unit 102 determines that the detected temperature Main_NC_T exceeds the start determination temperature, it immediately terminates the process and switches to normal control based on the detection result from the first temperature sensor 130.

[0104] Then, when the control unit 102 determines that the temperature detected by the first temperature sensor 130 is below the start determination temperature, it performs the following control. That is, starting from the temperature Main_NC_T detected by the first temperature sensor 130 when the halogen lamps 414a and 414b are turned on, it substitutes the slope of the actual temperature line obtained by the radiation thermometer 135 acquired by the offline bench and obtains the actual temperature line L2 as shown in Figure 10 (step 102). The acquisition of this actual temperature line L2 is obtained by substituting the value of the temperature Main_NC_T detected by the first temperature sensor 130 into the equation of the straight line L that represents the actual temperature line, which is stored in advance in the ROM 122. In other words, the actual temperature line L2 is the equation of the straight line L that passes through the temperature Main_NC_T detected by the first temperature sensor 130.

[0105] Next, the control unit 102 sequentially calculates the difference between the actual temperature line L2 and the temperature detected by the first temperature sensor 130. Then, as shown in Figure 9, the control unit 102 substitutes the obtained difference as a correction value into the readydown value (step 103).

[0106] Next, when the ready temperature and the temperature detected by the first temperature sensor 130 become equal and intersect, the control unit 102 transitions to a print status (step 104) to start the image forming operation, and terminates the control operation for that rise time.

[0107] Subsequently, the image forming apparatus 1 drives each image forming device 10, etc., as shown in Figure 1, and starts the image forming operation.

[0108] As described above, in the image forming apparatus 1 to which the fixing device 40 according to Embodiment 1 is applied, the surface temperature of the heating roll 41 is detected by the first temperature sensor 130 when heating of the heating roll 41 begins. Then, the control unit 102 determines whether the surface temperature of the heating roll 41 has reached the target temperature, which is the weight-up temperature, based on the surface temperature of the heating roll 41 detected by the first temperature sensor 130. In doing so, the control unit 102 corrects the detection delay of the first temperature sensor 130 by using data from the actual temperature line L2, which has been previously detected by a radiation thermometer 135 that has a higher response rate than the first temperature sensor 130, to detect the temperature change of the heating roll 41 at the start of heating.

[0109] Therefore, with the image forming apparatus 1 to which the fixing device 40 according to this embodiment 1 is applied, it is possible to quickly determine whether the surface temperature of the heating roll 41 has reached the target temperature, the weight-up temperature, with a response time comparable to that of detecting the surface temperature of the heating roll 41 with a highly responsive radiation thermometer 135 when heating of the heating roll 41 begins.

[0110] As a result, the image forming apparatus 1 to which the fixing device 40 according to Embodiment 1 is applied can shorten the weight-up time. Therefore, the printer can achieve internationally defined environmental standard values ​​for ultrafine particle dust (UFP) emissions, power consumption, and startup waiting time.

[0111] In the above embodiment, the determination unit was described in a case where it corrects the detection delay of the first temperature detection unit by changing the target temperature, but it is not limited to this. For example, the determination unit may be configured to correct the detection delay of the first temperature detection unit by changing the detection result of the first temperature detection unit.

[0112] In this case, the determination unit is configured to determine whether or not the target temperature has been reached by adding the difference between the detection result of the first temperature detection unit and the actual temperature detected by the second temperature detection unit to the detection result of the first temperature detection unit.

[0113] In the above embodiment, a color image forming apparatus equipped with yellow (Y), magenta (M), cyan (C), and black (K) image forming devices was described as the image forming apparatus. However, it goes without saying that the same can be applied to a monochrome image forming apparatus.

[0114] (Note) (((1))) A heating section heated by a heat source, A first temperature detection unit for detecting the temperature of the heating unit, A determination unit determines whether the heating unit has reached a target temperature by using the actual temperature previously detected by a second temperature detection unit, which has a higher response rate than the first temperature detection unit, to correct the detection delay of the first temperature detection unit, based on the temperature change of the heating unit at the start of heating. A fixing device equipped with the following features. (((2))) The fixing device according to (((1))), wherein the determination unit corrects the detection delay of the first temperature detection unit by changing the target temperature. (((3))) The fixing device according to (((2))), wherein the determination unit determines whether or not the target temperature has been reached by subtracting the difference between the actual temperature detected by the second temperature detection unit and the temperature detected by the first temperature detection unit from the target temperature. (((4))) The fixing device according to (((1))), wherein the determination unit corrects the detection delay of the first temperature detection unit by changing the detection result of the first temperature detection unit. (((5))) The fixing device according to (((4))), wherein the determination unit determines whether or not the target temperature has been reached by adding the difference between the detection result of the first temperature detection unit and the actual temperature detected by the second temperature detection unit. (((6))) The fixing device according to (((1))), wherein the first temperature detection unit consists of a non-contact type temperature sensor. (((7))) The fixing device according to (((1))), wherein the second temperature sensing unit consists of a radiation thermometer. (((8))) The fixing apparatus according to (((1))), wherein the determination unit holds the actual temperature previously detected by the second temperature detection unit as data approximated by a straight line. (((9))) The fixing apparatus according to (((1))), wherein the determination unit determines whether the heating unit has reached the target temperature when the detection result of the first temperature detection unit is less than or equal to a predetermined threshold, and does not determine whether the heating unit has reached the target temperature when the detection result of the first temperature detection unit exceeds a predetermined threshold. (((10))) Image forming means for forming an image on a recording medium, Fixing means for fixing the image onto the recording medium, Equipped with, An image forming apparatus using a fixing device as described in any of (((1))) to (((9))) as the fixing means.

[0115] According to the fixing device of (((1))), when determining whether the heating unit has reached the target temperature, it is possible to determine early whether the heating unit has reached the target temperature even when a first temperature detection unit with relatively low responsiveness is used, compared to not correcting the detection delay of the first temperature detection unit by using the actual temperature previously detected by a second temperature detection unit which has higher responsiveness than the first temperature detection unit used in the actual machine. According to the fixing device of (((2))), the determination unit can use the detection result of the first temperature detection unit as is, compared to when the target temperature is not changed. According to the fixing device described in (((3))), the determination unit can quickly determine whether the target temperature has been reached by using the detection result of the first temperature detection unit as is, by subtracting the difference between the actual temperature detected by the second temperature detection unit and the temperature detected by the first temperature detection unit from the target temperature, thereby correcting the detection delay of the first temperature detection unit. According to the fixing device of (((4))), the determination unit does not need to change the target temperature, compared to the case where the detection delay of the first temperature detection unit is corrected by changing the target temperature. According to the fixing device described in (((5))), the determination unit can determine whether or not the target temperature has been reached by adding the difference between the detection result of the first temperature detection unit and the actual temperature detected by the second temperature detection unit. According to the fixing device described in (((6))), the first temperature sensing unit can be made smaller and the cost of the device can be reduced compared to the case in which it is composed of a radiation thermometer. According to the fixing device of (((7))), the second temperature detection unit can improve responsiveness compared to the case in which it consists of a non-contact type temperature sensor. According to the fixing device of (((8))), the determination unit can reduce the amount of data compared to the case in which all actual temperatures previously detected by the second temperature detection unit are retained as data. According to the fixing device of (((9))), the determination unit can determine with greater accuracy whether or not the target temperature has been reached compared to the case where the determination is made when the detection result of the first temperature detection unit exceeds a predetermined threshold. According to the image forming apparatus of (((10))), even when employing a first temperature detection unit which has relatively lower responsiveness compared to not using the fixing device described in any of (((1))) to (((9))) as the fixing means, it is possible to quickly determine whether or not the heating unit has reached the target temperature. [Explanation of symbols]

[0116] 1…Image forming apparatus 1a...Main unit of the device 10Y~10K…Image forming device 40… Fixing device 41...Heated Roll 42…Compression belt 100...Control device 102... Control Unit 130...First temperature sensor 135...Radiation thermometer

Claims

1. A heating section heated by a heat source, A first temperature detection unit for detecting the temperature of the heating unit, A determination unit determines whether the heating unit has reached a target temperature by using the actual temperature previously detected by a second temperature detection unit, which has higher responsiveness than the first temperature detection unit, to correct the detection delay of the first temperature detection unit, based on the temperature change of the heating unit at the start of heating. A fixing device equipped with the following features.

2. The fixing device according to claim 1, wherein the determination unit corrects the detection delay of the first temperature detection unit by changing the target temperature.

3. The fixing device according to claim 2, wherein the determination unit determines whether or not the target temperature has been reached by subtracting the difference between the actual temperature detected by the second temperature detection unit and the temperature detected by the first temperature detection unit from the target temperature.

4. The fixing device according to claim 1, wherein the determination unit corrects the detection delay of the first temperature detection unit by changing the detection result of the first temperature detection unit.

5. The fixing device according to claim 4, wherein the determination unit determines whether or not the target temperature has been reached by adding the difference between the detection result of the first temperature detection unit and the actual temperature detected by the second temperature detection unit.

6. The fixing device according to claim 1, wherein the first temperature detection unit comprises a non-contact type temperature sensor.

7. The fixing device according to claim 1, wherein the second temperature detection unit comprises a radiation thermometer.

8. The fixing apparatus according to claim 1, wherein the determination unit holds data that approximates the actual temperature previously detected by the second temperature detection unit with a straight line.

9. The fixing apparatus according to claim 1, wherein the determination unit determines whether the heating unit has reached the target temperature when the detection result of the first temperature detection unit is below a predetermined threshold, and does not determine whether the heating unit has reached the target temperature when the detection result of the first temperature detection unit exceeds a predetermined threshold.

10. Image forming means for forming an image on a recording medium, Fixing means for fixing the image onto the recording medium, Equipped with, An image forming apparatus using the fixing device described in any one of claims 1 to 9 as the fixing means.

Images