KR20090075612A - Image forming apparatus, fusing device thereof and method of controlling fusing device - Google Patents

Abstract

An image forming device, a fixing device and a control method for fixing a toner image to the printing medium of the fixing device are provided to minimize the thermal loss of a fixing belt by reducing the area on which is a floodlighting member and a fixing belt are contacted. A heat source(130) is arranged in the inside of the fixing belt. A supporting member(150) is arranged between the heating source and fixing belt. The supporting member forms the heating source in an opening unit. A first temperature sensor measures the heated unit of the fixing belt and the temperature of the fixing belt.

Description

IMAGE FORMING APPARATUS, FUSING DEVICE THEREOF AND METHOD OF CONTROLLING FUSING DEVICE}

The present invention relates to an image forming apparatus, and more particularly, to an image forming apparatus having a fixing device for fixing a toner image to a print medium.

An image forming apparatus is an apparatus for forming an image on a print medium according to an input image signal. Examples of the image forming apparatus include a printer, a copier, a fax machine, and a multifunction printer incorporating these functions.

An image forming apparatus adopting an electrophotographic method scans light on a photosensitive member charged to a predetermined potential to form an electrostatic latent image on the surface of the photosensitive member, and then introduces toner into the latent image to form a visible image. The visible image formed on the photosensitive member is transferred directly to the printing medium or transferred to the printing medium via the intermediate transfer member, and the visible image transferred to the printing medium is fixed to the printing medium while passing through the fixing device.

In general, a fixing apparatus widely used includes a heating roller having a heat source therein and a pressure roller in close contact with the heating roller to form a fixing nip. When the print medium to which the toner image has been transferred enters between the heating roller and the pressure roller, the toner image is fixed to the printing medium by the heat transmitted from the inside of the heating roller and the pressure acting on the fixing nip.

In such a fixing device, since the heating roller itself has a large heat capacity, it takes considerable time to heat (warm up) the heating roller to a temperature at which fixing is possible at the time of initial driving of the image forming apparatus.

In recent years, in order to meet the demand for high speed of the image forming apparatus, a fixing apparatus has been developed to increase the temperature of the nip as quickly as possible to a fixing temperature. An example of such fixing apparatus is disclosed in US 2006/0177251. It is.

The fixing apparatus disclosed in the above document includes a pressing roller, a fixing belt driven and rotated by the pressing roller, a halogen heater installed inside the fixing belt to heat the fixing belt, and the fixing belt together with the pressure roller to form a fixing nip. It is configured to include a belt guide member for supporting the inner peripheral surface of the fixing belt.

Some of the heat radiated from the halogen heater heats the belt guide member near the fixing nip, and the fixing belt is indirectly heated by the heat transferred from the heated belt guide member. The other part of the heat radiated from the halogen heater directly heats the fixing belt on the opposite side of the fixing nip, whereby the fixing belt is heated to a predetermined temperature in a short time by the halogen heater.

According to the fixing device as described above, the fixing belt can be heated quickly to shorten the warm-up time.However, in a situation where the fixing device does not operate properly, the fixing belt may be damaged due to overheating of the fixing belt or a safety accident may occur. It is very likely to occur.

For example, if the fixing belt does not rotate properly due to slippage between the pressure roller and the fixing belt, or if the fixing belt does not rotate due to a problem in the drive system that transmits power to the pressure roller, As the temperature of the portion directly heated by the temperature rises rapidly, the fixing belt may be damaged, and further, a safety accident such as a fire may occur.

One aspect of the present invention provides an image forming apparatus and a method of controlling the fixing apparatus and the fixing apparatus to prevent the fixing belt from being damaged or a safety accident due to overheating of the fixing belt.

In addition, another aspect of the present invention provides an image forming apparatus and a method of controlling the fixing apparatus and the fixing apparatus, which can improve the print quality by reliably controlling the operation of the fixing apparatus.

According to an aspect of the present invention, an image forming apparatus includes a fixing belt, a heat source disposed inside the fixing belt, and an opening at least partially disposed between the heat source and the fixing belt and allowing heat radiated from the heat source to pass therethrough. And a fixing device including a support member having a formed temperature and a first temperature sensor measuring a temperature of the fixing belt at a heated portion of the fixing belt which is directly heated by radiant heat transmitted through the opening. And a control unit that controls the heat source based on the temperature measured by the control unit.

The first temperature sensor may measure a temperature by contacting an outer surface of the fixing belt.

The to-be-heated part includes a print medium contact part which comes into contact with a print medium passing through the fixing device, and an edge part which is located outside the print medium contact part, and wherein the first temperature sensor has a temperature of the fixing belt at the edge part. Can be measured.

The controller may determine whether to cut off the power applied to the heat source by calculating a temperature gradient of the fixing belt from the temperatures measured by the first temperature sensor and comparing it with a reference value.

The control unit may apply different reference values according to the temperature measured first by the first temperature sensor when comparing the temperature rising slope of the fixing belt with a reference value.

The controller may cut off power applied to the heat source when the temperature measured by the first temperature sensor is equal to or greater than a reference value.

The fixing device may further include an upper frame disposed on the support member, and the first temperature sensor may be installed on the upper frame.

The upper frame may include a base plate and a temperature sensor fixing part which extends inclined toward the fixing belt from the base plate.

The fixing device may further include a second temperature sensor for measuring the temperature of the fixing belt at the central portion of the fixing belt.

The second temperature sensor is in contact with the outer surface of the fixing belt, the support member includes a support plate extending along the width direction of the fixing belt, wherein the second temperature sensor is in contact with the fixing belt The inner surface of the fixing belt may be supported by the support plate.

The fixing apparatus further includes an upper frame disposed on the support member, wherein the first temperature sensor and the second temperature sensor are installed on the upper frame, and the upper frame is formed on the base plate and the base plate. It may include a first temperature sensor fixing portion extending inclined toward the fixing belt, and a second temperature sensor fixing portion extending vertically from the base plate toward the fixing belt.

The support member includes at least two ribs, wherein the first temperature sensor contacts the outer surface of the fixing belt to measure the temperature of the fixing belt, and wherein the first temperature sensor contacts the fixing belt. The inner surface of the fixing belt may be supported by the ribs.

A light transmitting member may be installed in the opening defined between the ribs.

The light transmitting member may include a protrusion protruding toward the fixing belt and contacting an inner surface of the fixing belt.

The fixing device further includes a pressing member for forming a fixing nip facing the fixing belt, and a nip forming member for supporting an inner surface of the fixing belt to form a fixing nip together with the pressing member. It may include an opening formed on the opposite side of the fixing nip so that the heat radiated from the heat source can pass.

In addition, the image forming apparatus according to the spirit of the present invention is a fixing belt having a heat source, a heated portion directly radiated by the heat source, and the temperature of the fixing belt in contact with the outer surface of the fixing belt in the heated portion A fixing device including a first temperature sensor to measure; and a controller configured to turn off the heat source when the temperature rising slope of the fixing belt calculated from the temperatures measured by the first temperature sensor is equal to or greater than a reference value. It is characterized by.

In addition, the image forming apparatus according to the spirit of the present invention is a heat source for generating heat, the first heated portion directly heated by the radiant heat of the heat source and the second heated portion indirectly heated by the heat transferred from the heat source. The fixing belt, a first temperature sensor for measuring the temperature of the fixing belt in the first heating portion of the fixing belt, and a second temperature for measuring the temperature of the fixing belt in the second heating portion of the fixing belt And a control unit for controlling the operation of the heat source according to the temperature of the fixing belt measured by the first temperature sensor and the second temperature sensor.

The image forming apparatus may further include at least one member disposed on a path through which the heat of the heat source is transferred to the fixing belt.

The at least one member may include an opening so that heat radiated from the heat source passes through the member to directly heat the first heated portion of the fixing belt.

The at least one member may prevent the heat radiated from the heat source directly heating the second heated portion of the fixing belt.

The first temperature sensor and the second temperature sensor may measure the temperature of the fixing belt at different positions in the rotation direction of the fixing belt.

The first temperature sensor and the second temperature sensor may measure the temperature of the fixing belt at different positions in the width direction of the fixing belt.

The fixing belt forms a pressing member and a fixing nip which are installed to face the fixing belt, and the second temperature sensor may measure the temperature of the fixing belt near the fixing nip.

The at least one member includes a support member having at least a portion disposed between the heat source and the fixing belt, wherein the support member has heat radiated from the heat source passing through the support member so that the first heated portion of the fixing belt It may have an opening to heat directly.

And a pressurizing member facing the fixing belt, wherein the pressing member is disposed between the heat source and the fixing belt and supports an inner surface of the fixing belt to form a fixing nip between the outer surface of the fixing belt and the pressing member. The nip forming member may further include an opening such that heat radiated from the heat source passes through the nip forming member to directly heat the first heated portion of the fixing belt.

The control unit determines the first temperature rising slope of the fixing belt from temperatures measured at time intervals in the first temperature sensor, and the first temperature of the fixing belt is determined from temperatures measured at time intervals in the second temperature sensor. Determination of the second temperature gradient, the first temperature gradient and the second temperature gradient can be compared with the first reference value and the second reference value, respectively.

The controller may shut off power applied to the heat source when the first temperature rising slope is greater than the first reference value and the second temperature rising slope is less than the second reference value.

The controller may determine whether an overvoltage or undervoltage is applied to the heat source based on a result of comparing the first elevated temperature gradient with the first reference value and a result of comparing the second elevated temperature gradient with the second reference value.

When it is determined that an overvoltage or a low voltage is applied to the heat source, the controller may adjust a duty ratio of the heat source.

In addition, the fixing device according to the spirit of the present invention is a fixing belt; and a heat source disposed inside the fixing belt; and a pressing member for forming a fixing nip facing the fixing belt; and the pressing by supporting the inner surface of the fixing belt A nip forming member which forms a fixing nip together with the member and has an opening so that heat radiated from the heat source can directly heat the fixing belt; and heat disposed outside the nip forming member and radiated from the heat source. A support member having an opening formed to directly heat the fixing belt; and a first temperature sensor measuring a temperature of the fixing belt at a position corresponding to the opening of the nip forming member and the opening of the supporting member. Characterized in that.

At least one of the nip forming member and the supporting member includes a blocking portion that prevents radiant heat of the heat source from being directly transmitted to the fixing belt, and the fixing device does not directly transmit radiant heat of the heat source by the blocking portion. It may further include a second temperature sensor for measuring the temperature of the fixing belt in the portion.

In addition, the control method of the fixing device according to the spirit of the present invention is a control method of a fixing device including a fixing belt disposed around the heat source, the temperature of the portion to be heated directly by the radiant heat of the heat source in the fixing belt Is the first measurement; Measuring the temperature of the portion to be heated of the fixing belt for a second time; Determining a temperature rising slope of the fixing belt from the first measured temperature and the second measured temperature; Comparing the temperature gradient with a reference value; And controlling the operation of the heat source based on a result of comparing the temperature gradient with the reference value.

Any one of a plurality of values may be selected as the reference value based on the first measured temperature in the heated portion.

And the control method determines that an error has occurred if the temperature rising slope is equal to or greater than the reference value; Count the number of times the error occurred; Determine whether the number of error occurrences is equal to a reference number; The method may further include shutting off power applied to the heat source when the number of error occurrences is the same as a reference number.

In addition, the control method of the fixing device according to the spirit of the present invention is a control method of a fixing device including a fixing belt disposed around the heat source, the first heating to be directly heated by the radiant heat of the heat source in the fixing belt Firstly measuring the negative temperature and the temperature of the second heated portion indirectly heated by the heat transferred from the heat source in the fixing belt; Secondly measuring the temperature of the first heated portion and the temperature of the second heated portion; Determining a temperature rising slope of the first heated portion from the first measured temperature and the second measured temperature in the first heated portion; Determining a temperature gradient of the second heated portion from the first measured temperature and the second measured temperature in the second heated portion; And comparing the temperature rising slope of the first heated portion with a first reference value and comparing the temperature rising slope of the second heated portion with a second reference value.

The operation of the heat source may be controlled according to a result of comparing the temperature gradients with a reference value.

When the temperature rising slope of the first heated portion is greater than the first reference value and the temperature rising slope of the second heated portion is less than the second reference value, power applied to the heat source may be cut off.

When the temperature rising slope of the first heated portion is greater than the first reference value and the temperature rising slope of the second heated portion is greater than the second reference value, it may be determined that an overvoltage is applied to the heat source.

When the temperature rising slope of the first heated portion is smaller than the first reference value and the temperature rising slope of the second heated portion is smaller than the second reference value, it may be determined that a low voltage is applied to the heat source.

The duty ratio of the heat source may be adjusted according to a result of comparing the temperature gradients with a reference value.

According to a result of comparing the temperature gradients with a reference value, information about the operation of the fixing device may be displayed on the display unit.

Embodiments of the present invention is configured so that the heat source can be directly radiant heating the fixing belt can quickly increase the temperature of the fixing belt. This shortens the warm-up time and enables high speed printing.

In addition, according to embodiments of the present invention it is possible to prevent the fixing belt is overheated and damaged or a safety accident does not occur if the fixing belt does not rotate properly.

In addition, according to embodiments of the present invention it is possible to reliably control the fixing device to improve the print quality.

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described in detail. 1 is a diagram illustrating a configuration of an image forming apparatus according to an embodiment of the present invention.

As shown in FIG. 1, the image forming apparatus 1 may include a print medium supply device 10, a light scanning device 20, a developing device 30, a transfer device 40, a fixing device 100, and a print medium. It is configured to include a discharge device (50).

The print medium supply device 10 supplies the print medium S to the developing device 30. The print medium supply apparatus 10 includes a tray 11 on which the print medium S is loaded, and a pickup roller 12 that picks up the print media loaded on the tray 11 one by one. The print medium picked up by the pickup roller 12 is transferred toward the developing apparatus 30 by the transfer roller 13.

The developing device 30 develops a toner image in accordance with image information input from an external device such as a computer. The image forming apparatus 1 according to the present embodiment is a color image forming apparatus, and the developing apparatus 30 includes toners of different colors, for example, yellow (Y), magenta (M), cyan (C), and black ( K) It consists of four developing devices 30Y, 30M, 30C, and 30K, each containing toner of color.

Each developing device 30Y, 30M, 30C, 30K is provided with the photosensitive member 31 by which the electrostatic latent image is formed in the surface by the optical scanning apparatus 20. As shown in FIG. The optical scanning device 20 irradiates the photosensitive members 31 of each developing device with light corresponding to image information of yellow (Y), magenta (M), cyan (C), and black (K) colors according to a print signal.

Each of the developing devices 30Y, 30M, 30C, and 30K includes a charging roller 32 for charging the photosensitive member 31, a developing roller 33 for supplying toner images to the electrostatic latent images formed on the photosensitive members 31, and a developing roller. A supply roller 34 for supplying the toner to the 33 may be provided.

The transfer device 40 transfers the toner image developed on the photosensitive member 31 to a print medium. The transfer device 40 maintains the tension of the transfer belt 41, the transfer belt drive roller 42 for driving the transfer belt 41, and the transfer belt 41 in contact with each photosensitive member 31. And a tension roller 43, and four transfer rollers 44 for transferring the toner image developed on the photosensitive member 31 to a print medium.

The print medium is attached to the transfer belt 41 and transported at the same speed as the traveling speed of the transfer belt 41. At this time, each transfer roller 44 is applied with a voltage having a polarity opposite to that of the toner attached to each photosensitive member 31, so that the toner image on the photosensitive member 31 is transferred to the printing medium.

The fixing device 100 fixes the toner image transferred to the print medium through the transfer device 40 to the print medium. Detailed description of the fixing device 100 will be described later.

The print medium discharging device 50 discharges the print medium to the outside of the image forming apparatus 1. The printing medium discharge device includes a discharge roller 51 and a discharge backup roller 52 which is installed to face the discharge roller 51.

2 to 4 is a cross-sectional view, a combined perspective view and an exploded perspective view showing the configuration of the fixing device according to an embodiment of the present invention. 2 and 4 omit some of the configuration. In addition, in FIG. 2, the first temperature sensor 190 and the second temperature sensor 200 are not positioned on the same plane, but are shown in one drawing for convenience.

2 to 4, the fixing device 100 includes a main frame 110, a fixing belt 120, a heat source 130, a pressing member 140, and a supporting member 150. . The print medium S on which the toner image is transferred passes between the pressing member 140 and the fixing belt 120. At this time, the toner image is fixed to the print medium by heat and pressure.

The main frame 110 supports various components constituting the fixing device and is fixed to a main frame (not shown) provided in the image forming apparatus.

The pressing member 140 is disposed to face the fixing belt 120 and is pressed toward the fixing belt 120 by a pressing unit (not shown) to form a fixing nip N. The pressure member 140 may be configured as a pressure roller 140a that rotates by receiving power from a driving source (not shown).

The pressure roller 140a has a shaft 141 formed of a metal material such as aluminum or steel, and a fixing nip between the pressure roller 140a and the fixing belt 120 while elastically deforming as the pressure roller 140a is pressed toward the fixing belt 120. And an elastic layer 142 forming N). The elastic layer 142 is typically formed of silicone rubber, and a release layer 143 is formed on the surface of the elastic layer 142 to prevent the print medium from adhering to the pressure roller 140a.

The fixing belt 120 may be rotatably supported by the support member 150. The fixing belt 120 is engaged with the pressure roller 140a and rotates to form the fixing nip N together with the pressure roller 140a.

The fixing belt 120 is formed of a heat resistant material and has a width corresponding to the length of the pressure roller 140a. The fixing belt 120 is heated by the heat source 130 to transfer heat to the print medium (S) passing through the fixing nip (N).

The heat source 130 is disposed inside the fixing belt 120. Both ends of the heat source 130 are respectively coupled to the side cover 160, the side cover 160 is fixed to the support member 150, so that the heat source 130 is supported by the support member 150. As the heat source 130, a halogen lamp may be used.

The support member 150 is formed to surround the heat source 130 and is formed of a material having a large rigidity such as steel so as not to be easily deformed by external force.

The support member 150 may include two side parts 151, two support plates 152, and two bending plates 153.

The two side parts 151 are disposed on both sides of the support member 150, and the belt support part 151a for supporting the ends of the fixing belt 120 protrudes from the inner side surfaces of the two side parts 151. The two side parts 151 may be formed integrally with the support member 150 or may be provided as separate members separated from the support member 150.

The two support plates 152 extend in the width direction between the two side parts 151. The two support plates 152 are arranged side by side in the front-rear direction while being spaced apart from each other.

The two bending plates 153 are bent inwardly at each support plate 152. The first opening 154 is defined between the two bending plates 153. Some of the heat radiated from the heat source 130 passes through the first opening 154 and is transferred toward the fixing nip N.

The support member 150 has a second opening 155 formed on the opposite side of the first opening 154. The second opening 155 allows the radiant heat of the heat source 130 to directly pass through the support member 150 to reach the fixing belt 120. Hereinafter, the portion to be heated directly radiated through the second opening 155 of the support member 150 in the fixing belt 120 is called a first portion to be heated, and is denoted by reference numeral '121'.

In this embodiment, the support plate 152 of the support member 150 is disposed between the heat source 130 and the fixing belt 120 to prevent the radiant heat of the heat source 130 from being directly transmitted to the fixing belt 120. . Hereinafter, a portion of the heat source 130 that is not directly transmitted to the fixing belt 120 and is indirectly heated by the heat source 130 is called a second to-be-heated portion and is denoted by reference numeral 122.

In addition, the support member 150 may be provided with a reinforcing plate 156 connecting the two side portions 151 from the outside of the fixing belt 120. The reinforcing plate 156 reinforces the strength of the support member 150 to prevent the support member 150 from being deformed.

Also, as shown in FIGS. 2 and 4, the fixing device 100 may include a nip forming member 170 and a belt guide member 180.

The nip forming member 170 supports the inner surface of the fixing belt 120 so that the fixing nip N is formed between the pressure roller 140a and the fixing belt 120.

The nip forming member 170 includes a body portion 170a and a nip forming portion 170b. The nip forming portion 170b extends toward the fixing belt 120 from the first extension portion 171 extending from one end of the body portion 170a toward the fixing belt 120 and from the other end of the body portion 170a. The 2nd extension part 172 and the press part 173 provided in the edge part of the 1st extension part 171 and the 2nd extension part 172 are provided. One side of the pressing unit 173 is to press the inner surface of the fixing belt 120 so that the fixing nip (N) can be formed.

A nip heating part 174 is defined between the first extension part 171 and the second extension part 172. The heat source 130 directly radiates and heats the pressing unit 173 through the nip heating unit 174 of the nip forming member 170, and the heated pressing unit 173 transfers heat to the fixing belt 120. .

Nip forming member 170 is preferably formed of a metal material having a low specific heat and good thermal conductivity so that the temperature rises quickly to effectively transfer heat to the fixing belt 120 and the print medium (S). For example, the nip forming member 170 may be formed of aluminum, steel, copper or phosphor bronze.

The body portion 170a of the nip forming member 170 has an opening 175 formed on the opposite side of the nip heating portion 174. The heat source 130 directly radiantly heats the first heated portion 121 of the fixing belt 120 through the opening 175 of the nip forming member 170 and the second opening 155 of the supporting member 150. can do. Accordingly, the temperature of the fixing belt 120 can be increased more quickly, and the temperature of the fixing belt 120 can be prevented from being lowered while the fixing belt 120 is being rotated.

The belt guide member 180 supports the inner surface of the fixing belt 120 near the fixing nip N to guide the fixing belt 120. The belt guide member 180 may be formed of a heat resistant plastic such as Polyether Ether Ketone (PEEK), Polyphenylene Sulfide (PPS), or the like.

An upper portion of the belt guide member 180 is supported by the support member 150, and an opening portion 181 corresponding to the nip heating portion 174 of the nip forming member 170 is provided at the center of the belt guide member 180. Is formed.

The lower surface of the belt guide member 180 is the other side of the pressing portion 173 of the nip forming member 170 (opposite side of the surface supporting the fixing belt 120) against the pressing force acting from the pressing roller 140a. Support and press In addition, the inner surface of the opening 181 of the belt guide member 180 and the first extension portion 171 of the nip forming member 170 so that the gap between the nip heating portion 174 of the nip forming member 170 is not enlarged. The outside of the second extension portion 172 is supported.

In addition, as shown in FIGS. 2 and 4, the fixing device 100 is directly radiated by the heat source 130 in the fixing belt 120, that is, in the first heating part 121 of the fixing belt 120. A first temperature sensor 190 for measuring the temperature of the fixing belt 120 is provided. The image forming apparatus 1 may prevent overheating of the fixing belt 120 by taking appropriate measures based on the temperature measured by the first temperature sensor 190.

The first heated portion 121 of the fixing belt 120 is provided at the outer side of the print medium contact portion 121a and the print medium contact portion 121a which are brought into contact with the print medium S when the fixing belt 120 rotates. It is divided into an edge portion 121b which is positioned and does not contact the print medium S.

The first temperature sensor 190 is installed to contact the outer surface of the fixing belt 120 in the edge portion 121b to measure the temperature of the fixing belt 120. Since the edge portion 121b of the first heated portion 121 does not transmit heat to the print medium S, the temperature is maintained relatively higher than that of the print medium contact portion 121a, and overheating of the fixing belt 120 is prevented. In terms of prevention, it is preferable to monitor the temperature of the fixing belt 120 in the edge portion 121b at which the temperature is kept high. In addition, as the first temperature sensor 190 is installed to contact the fixing belt 120, scratches may occur on the surface of the fixing belt 120. Damage of the fixing belt 120 may affect the print quality. It is also preferable to install the first temperature sensor 190 in the edge portion 121b from the aspect of avoiding falling.

In addition, the fixing device 100 may include a second temperature sensor 200. The image forming apparatus 1 allows the fixing belt 120 to maintain the fixing temperature at an appropriate level based on the temperature measured by the second temperature sensor 200. In addition, the image forming apparatus 1 may more reliably determine whether the fixing belt 120 is overheated by utilizing the temperature measured by the second temperature sensor 200 together with the temperature measured by the first temperature sensor 190. Can be.

The second temperature sensor 200 is indirectly heated by the structure (for example, the support plate 152 of the support member) disposed between the heat source 130 and the fixing belt 120. The second heated portion 122 of the may be arranged to measure the temperature of the fixing belt 120.

When the first temperature sensor 190 is arranged to measure the temperature of the fixing belt 120 at the first position P1, the second temperature sensor 200 is located in the first position in the rotational direction of the fixing belt 120. It may be arranged to measure the temperature of the fixing belt 120 at the second position (P2) downstream from (P1). At this time, the second temperature sensor 200 may be arranged to measure the temperature of the fixing belt 120 in the vicinity of the fixing nip (N).

In addition, the second temperature sensor 200 may measure the temperature of the fixing belt 120 at a position different from the first temperature sensor 190 in the width direction of the fixing belt 120. The second temperature sensor 200 may be installed to be positioned at the center portion in the width direction of the fixing belt 120 and may contact the outer surface of the fixing belt 120 to measure the temperature of the fixing belt 120.

2 and 4, the upper frame 210 is installed on the upper portion of the support member 150, and the first temperature sensor 190 and the second temperature sensor 200 are mounted on the upper frame 210. Can be fixed.

The upper frame 210 includes a base plate 211, a first temperature sensor fixing part 212 extending inclined toward the fixing belt 120 from the base plate 211, and the fixing belt 120 from the base plate 211. It includes a second temperature sensor fixing portion 213 extending vertically toward).

One side of the first temperature sensor 190 is fixed to the first temperature sensor fixing unit 212 through a screw, the other side of the first temperature sensor 190 is inclined toward the fixing belt 120 is extended to the fixing belt 120 Contact the outer surface of the The other side of the first temperature sensor 190 is provided with a sensing element 191, the sensing element 191 may be composed of a thermistor (thermistor). The sensing element 191 is protected by the protective film 192.

One side of the second temperature sensor 200 is fixed to the second temperature sensor fixing part 213 through a screw. The other side of the second temperature sensor 200 extends vertically toward the fixing belt 120 to contact the outer surface of the fixing belt 120. Like the first temperature sensor 190, the sensing element 201 and the protective film 202 are provided on the other side of the second temperature sensor 200.

In the part where the second temperature sensor 200 contacts the fixing belt 120, the inner surface of the fixing belt 120 may be supported by the supporting plate 152 of the supporting member 150 as shown in FIG. 2. Then, the flow of the fixing belt 120 (the central portion of the fixing belt 120 at which the second temperature sensor 200 measures the temperature is different from the portion where the second temperature sensor 200 contacts the fixing belt 120). By controlling the flow more severely), the second temperature sensor 200 can stably measure the temperature of the fixing belt 120.

5 is a block diagram illustrating control of a heat source in the image forming apparatus according to the exemplary embodiment of the present invention.

As shown in FIG. 5, the image forming apparatus 1 includes a control unit 60, a memory unit 90, a switching unit 70, and a display unit 80.

The controller 60 calculates the temperature gradient of the fixing belt 120 from the temperature measured by the first temperature sensor 190, and controls the heat source 130 according to the calculation result to thereby control the temperature of the fixing belt 120 in an abnormal situation. Can be prevented from rising rapidly.

More specifically, the controller 60 measures the temperature of the first heated portion 121 of the fixing belt 120 two times with a time difference, and measures the first measured temperature T1 and the second measured temperature ( The temperature gradient VT of the first to-be-heated part 121 of the fixing belt 120 is calculated from T2). If it is determined that the calculated temperature gradient VT is equal to or greater than a predetermined reference value Vr, the controller 60 cuts off the power applied to the heat source 130 through the switching unit 70.

At this time, the reference value Vr of the temperature rising slope may be set to a different value according to the temperature T1 measured first by the first temperature sensor 190. For example, when the primary measured temperature T1 is 150 ° C. or less, V1 may be set as the reference value. When T1 is more than 150 ° C. and 175 ° C. or less, V2 may be set as the reference value. In addition, when T1 is over 175 degreeC, V3 can be set as a reference value. Where V2 is less than V2 and V2 is less than V1. For example, V1 = 17 ° C./s, V2 = 15 ° C./S, V2 = 13 ° C./s.

Applying different reference values according to the temperature T1 is because the risk of overheating of the fixing belt 120 increases as the temperature of the fixing belt 120 increases, so it is necessary to apply more stringent standards.

In addition, the controller 60 does not immediately turn off the heat source 130 when an error occurs (when the temperature rising slope VT of the calculated fixing belt 120 is greater than or equal to the reference value), and the error occurs repeatedly, and the error count is predetermined. When the reference value is reached, the heat source 130 may be turned off. It is preferable in terms of stability to turn off the heat source 130 immediately if an error occurs at any time. However, a situation where the operation of the image forming apparatus 1 is stopped frequently occurs even though it is not a serious situation. It can make a bad impression on you.

In addition, the control unit 60 is the temperature measured by the temperature gradient of the first heated portion 121 of the fixing belt 120 and the second temperature sensor 200 calculated from the temperatures measured by the first temperature sensor 190. The heat source 130 may be controlled in consideration of the rising slope of the second heating unit 122 of the fixing belt 120 calculated from the same. Then, even when a voltage other than the rated voltage is applied to the heat source 130 of the fixing apparatus 100, overheating of the fixing belt 120 can be prevented more reliably.

Hereinafter, the temperature rising slope (temperature rising slope determined by the first heating unit 121) of the fixing belt 120 determined from the temperatures measured at intervals of time by the first temperature sensor 190 may be referred to as a first temperature rising slope. And, the temperature rising slope of the fixing belt 120 (temperature rising slope determined in the second heating unit 122) determined from the temperatures measured at time intervals in the second temperature sensor 200 is called a second temperature rising slope. do.

In consideration of the actual use environment in which the rated voltage may not be applied to the heat source 130 of the fixing apparatus 100, the image forming apparatus 1 may be operated normally even under a voltage variation of ± 20% at the rated voltage. Is designed.

However, in consideration of the case where the rated voltage is not applied to the heat source 130, only the temperature rising slope (first temperature rising slope) of the first heated portion 121 that is directly heated by the radiant heat of the heat source 130 is monitored. A situation may arise in which the fixing belt 120 may not reliably cope with an abnormal situation in which the fixing belt 120 is overheated.

For example, in a situation in which an overvoltage higher than the rated voltage is applied to the heat source 130 of the fixing device 100, even when the fixing belt 120 operates normally, a relatively high first temperature rising slope is displayed. In a situation where a low voltage is applied to the forming apparatus 1, the fixing belt 120 may have a value similar to the first temperature rising slope when the fixing belt 120 is overheated. Therefore, when the fixing device 100 is controlled only on the basis of the first temperature rising slope, a situation in which power applied to the heat source 130 is cut off may occur even when the fixing belt 120 operates normally.

When the fixing belt 120 is rotated normally, the first heating temperature slope determined by the first heated portion 121 of the fixing belt 120 and the second heated portion 122 of the fixing belt 120 are determined. The two slopes have similar values (see Table 1 below).

However, when an abnormal situation occurs in which the fixing belt 120 stops or rotates at an abnormally slow speed, the temperature rising slope of the first heated portion 121 that is directly heated by radiant heat to the heat source 130 is fixed to the fixing belt 120. (C) has a larger value when normal operation at the rated voltage, while the temperature rising slope of the second heated portion 122 that is indirectly heated by the heat source 130 is normal to the fixing belt 120 at the rated voltage. Will have a smaller value. This tendency can be confirmed in the experimental example shown in Table 1.

Table 1 below shows the first of the fixing belt 120 when the fixing belt 120 operates normally under various applied voltage conditions and when the fixing belt 120 stops and overheats (over operating). It is an example showing the result of calculating the temperature gradient and the second temperature gradient. In the table below, the voltage of 220V ~ 240V is considered as the rated voltage. The unit of temperature rising slope is ° C / s.

Operation over fixing belt Fixing Belt Normal Operation 1st slope 2nd temperature gradient 1st slope 2nd temperature gradient 154 V 10.30 3.17 3.98 4.29 165 V 13.17 3.67 5.55 5.91 176 V 14.25 4.83 5.73 6.10 187 V 16.78 6.52 6.70 7.31 198 V 18.53 6.16 7.46 8.15 220 V (rated) 19.79 6.52 9.10 9.50 240 V (rated) 22.13 7.11 11.12 11.60 264 V 25.74 7.66 12.97 13.50 275 V 26.32 8.43 14.64 15.20 286 V 29.43 8.71 16.14 16.80

TABLE 1

Therefore, the control unit 60 compares the first temperature rising slope of the fixing belt 120 with the first reference value and the second temperature rising slope of the fixing belt 120 with the second reference value, so that the first temperature rising slope is higher than the first reference value. When the large and the second temperature rising slope is smaller than the second reference value, the overheating of the fixing belt 120 may be prevented by cutting off the power applied to the heat source 130 through the switching unit 70. Here, the first reference value and the second reference value may be determined as a first rising slope value and a second rising slope value when the fixing belt 120 operates normally at the rated voltage. For example, referring to Table 1 above, the first reference value may be determined to be 9.10 ° C / s, and the second reference value may be 9.50 ° C / s.

In addition, in the normal operation of the fixing belt 120, the control unit 60 may overvoltage or undervoltage the heat source 130 according to a result of comparing the first temperature rising slope with the first reference value and the result of comparing the second temperature rising slope with the second reference value. It is possible to determine whether this is applied to properly control the duty ratio (duty ratio) of the heat source 130 according to the result. Specifically, the controller 60 lowers the duty ratio of the heat source 130 when it is determined that an overvoltage is applied to the heat source 130, and increases the duty ratio of the heat source 130 when it is determined that a low voltage is applied to the heat source 130. . Then, an overshoot may be reduced when an overvoltage is applied to the heat source 130, and a temperature of the fixing belt 120 may be increased more quickly in a situation where a low voltage is applied to the heat source 130. .

The memory unit 90 stores various data necessary for controlling the fixing apparatus 100. In detail, the memory unit 90 stores data about a temperature rising slope of the fixing belt 120 that changes according to the voltage applied to the heat source 130. This data includes first and second temperature gradient values for the case in which the fixing belt 120 operates normally and the belt is stopped and overheated.

The display unit 80 displays the operation state of the image forming apparatus 1 to the user. If it is determined that the fixing belt 120 is overheated, the controller 60 may display an error message on the display unit 80 to inform the user of an abnormal situation. In addition, when it is determined that an overvoltage or a low voltage is applied to the heat source 130, the controller 60 may display information on the display unit 80.

In the above, an example of controlling the heat source 130 by monitoring the temperature gradient of the fixing belt 120 has been described. Alternatively, the heat source 130 when the temperature measured by the first temperature sensor 190 is greater than or equal to a predetermined reference value. It is also possible to turn off.

Meanwhile, the controller 60 controls the fixing device 100 to maintain the proper temperature band through the temperature measured by the second temperature sensor 200. For example, assume that the target temperature range is TL or more and TH or less. Then, when the temperature measured by the second temperature sensor 200 is less than TL, the controller 60 turns on the heat source 130 as a signal having a large duty ratio through the switching unit 70, When the temperature measured by the second temperature sensor 200 exceeds TH, the temperature of the fixing belt 120 may be maintained within the target band by turning on the heat source 130 with a signal having a small duty ratio. do.

Hereinafter, operations of the image forming apparatus according to an exemplary embodiment of the present invention will be described with reference to FIGS. 1, 2, and 6. 6 is a flowchart illustrating a method of controlling a heat source using a first temperature sensor in the image forming apparatus according to an embodiment of the present invention.

When the image forming apparatus 1 is turned on, the image forming apparatus enters the warm-up mode. In the warming-up mode, the heat source 130 of the fixing device 100 heats the fixing belt 120 to an appropriate temperature at which the fixing operation can be performed. The heat source 130 heats the nip forming member 170, and the heated nip forming member 170 transmits heat to the fixing belt 120 through the pressing unit 173.

In addition, the heat source 130 directly radiates and heats the fixing belt 120 through the second openings 155 and 175 formed on the nip forming member 170 and the supporting member 150. As such, the heat source 130 directly heats the fixing belt 120, thereby rapidly increasing the temperature of the fixing belt 120.

When the fixing belt 120 is heated to an appropriate temperature, a printing operation is started according to a user's printing command. That is, the electrostatic latent image corresponding to the image information is formed on the surface of the photosensitive member 31 by the optical scanning device 20, and the developing apparatus 30 supplies the toner to the photosensitive member 31 to develop the electrostatic latent image as a toner image. . Meanwhile, the print medium S is supplied through the print medium supply device 10, and the transfer device 40 transfers the toner image on the photosensitive member 31 to the print medium S. FIG. The print medium on which the toner image is transferred passes between the pressing roller 140a and the fixing belt 120 in the fixing device 100. At this time, the toner image of the paper is fixed to the paper by the heat transmitted from the fixing belt 120 and the pressure acting between the pressure roller 140a and the fixing belt 120.

In the warm-up mode or the printing mode as described above, the control unit 60 prevents overheating of the fixing belt 120 by monitoring the temperature of the fixing belt 120 through the first temperature sensor 190.

As shown in FIG. 6, when the operation of monitoring the temperature of the fixing belt 120 is started, the controller 60 initializes the error number n (S302) and then fixes the fixing belt 120 through the first temperature sensor 190. The first temperature is measured (S304). The primary measured temperature is T1.

Next, the control part 60 determines whether the predetermined time (DELTA) t has passed (S306). Preferably, the predetermined time Δt is 500 ms.

After a predetermined time (Δt) has elapsed, the controller 60 measures the temperature of the fixing belt 120 through the first temperature sensor 190 (S308). The second measured temperature is T2.

The controller 60 calculates the temperature gradient VT of the fixing belt 120 from the measured temperatures T1 and T2 (S310). The temperature gradient VT of the fixing belt 120 may be calculated from (T2-T1) / Δt.

Then, the control unit 60 determines the reference value Vr related to the temperature rising slope of the fixing belt 120 according to the first measured temperature T1 (S312). For example, when T1 is 150 degrees C or less, it determines with Vr = 17 degreeC / s, and when T1 is more than 150 degreeC and 175 degrees C or less, it determines with Vr = 15 degreeC / s, and when T1 is more than 175 degreeC. Vr = 13 ° C./s can be determined.

When the reference value for the temperature gradient is determined, the controller 60 determines whether the temperature gradient VT of the fixing belt 120 calculated in S310 is equal to or greater than the reference value Vr (S314).

As a result of the determination in S314, when it is determined that the temperature rising slope VT of the fixing belt 120 is equal to or greater than the reference value Vr, the controller 60 recognizes that an error has occurred and counts the number of errors n (S316). It is determined whether the counted error number has reached a predetermined reference value N (S318). The reference value N of the number of errors may preferably be set three times.

As a result of S318, when it is determined that the error number n reaches the reference value N, the controller 60 recognizes that the fixing belt 120 is overheated and is applied to the heat source 130 through the switching unit 70. Cut off the power (S320). In addition, the controller 60 notifies the user of an abnormal situation by displaying an error message through the display unit 80 (S322).

On the other hand, if it is determined in S318 that the error number n has not reached the reference value N, it is fed back to S304 to proceed with the subsequent operation. In addition, when it is determined in S314 that the temperature rising slope VT of the fixing belt 120 is less than the reference value Vr, the monitoring operation is terminated.

7 is a flowchart illustrating a method of determining whether the fixing belt is normally operated using the first temperature sensor and the second temperature sensor in the image forming apparatus according to an embodiment of the present invention.

As shown in FIG. 7, when the operation of monitoring the temperature of the fixing belt 120 is started in the warm-up mode or the printing mode, the control unit 60 controls the first blood of the fixing belt 120 through the first temperature sensor 190. The temperature of the heat unit 121 is first measured, and the temperature of the second heating unit 122 of the fixing belt 120 is first measured through the second temperature sensor 200 (S502). The temperatures of the fixing belt 120 first measured in the first to-be-heated part 121 and the second to-be-heated part 122 are T ₁₁ and T _21, respectively.

Subsequently, the controller 60 determines whether the predetermined time DELTA t has elapsed (S504). Preferably, the predetermined time Δt is 500 ms.

After the predetermined time Δt elapses, the controller 60 measures the temperature of the fixing belt 120 through the first temperature sensor 190 and the second temperature sensor 200 (S506). The temperatures of the fixing belt 120 measured second by the first to-be-heated part 121 and the second to-be-heated part 122 are T ₁₂ and T _22, respectively.

The controller 60 calculates the temperature rising slope V _T1 , that is, the first temperature rising slope of the fixing belt 120 in the first to-be-heated part 121, from the measured temperatures T ₁₁ and T ₂₁ . ₁₂ and T ₂₂ to calculate the temperature gradient V _T2 , that is, the second temperature gradient of the fixing belt 120 in the second to-be-heated portion 122 (S508).

Thereafter, the controller 60 compares the first temperature gradient V _T1 of the fixing belt 120 calculated at S508 with the first reference value V _r1 (S510).

As a result of the comparison of S510, when it is determined that the first temperature gradient V _T1 of the fixing belt 120 is greater than the first reference value V _r1 , the controller 60 generates the second temperature of the fixing belt 120 calculated in S508. The slope V _T2 is compared with the second reference value V _r2 (S512). Here, the first reference value V _r1 and the second reference value V _r2 may be determined as a first rising slope value and a second rising slope value when the fixing belt 120 operates normally at the rated voltage. For example, referring to Table 1, the first reference value may be determined to be 9.10 ° C / s, and the second reference value may be 9.50 ° C / s.

As a result of the comparison of S512, when it is determined that the second temperature gradient V _T2 of the fixing belt 120 is smaller than the second reference value V _r2 , the controller 60 is applied to the heat source 130 through the switching unit 70. The power is cut off (S514). In addition, the controller 60 notifies the user of an abnormal situation by displaying an error message through the display unit 80 (S516).

On the other hand, as a result of the comparison between S510 and S512, the first temperature gradient V _T1 of the fixing belt 120 is equal to or less than the first reference value V _r1 , or the second temperature gradient V _T2 of the fixing belt 120 is equal to the second reference value. If it is determined that the error is V _r2 or higher, the current monitoring operation is terminated.

8 is a flowchart illustrating a method of controlling a heat source using a first temperature sensor and a second temperature sensor when the fixing belt is normally operated in the image forming apparatus according to an embodiment of the present invention.

As shown in FIG. 8, when the fixing belt 120 starts to monitor the temperature of the fixing belt 120 in a normal operation state, the controller 60 controls the fixing belt 120 through the first temperature sensor 190. The temperature of the first heated portion 121 is first measured, and the temperature of the second heated portion 122 of the fixing belt 120 is first measured through the second temperature sensor 200 (S602). The temperatures of the fixing belt 120 first measured in the first to-be-heated part 121 and the second to-be-heated part 122 are T ₁₁ ′ and T ₂₁ ′, respectively.

Next, the control part 60 determines whether the predetermined time (DELTA) t has passed (S604). After the predetermined time Δt elapses, the controller 60 measures the temperature of the fixing belt 120 through the first temperature sensor 190 and the second temperature sensor 200 (S606). The temperatures of the fixing belt 120 measured second by the first to-be-heated part 121 and the second to-be-heated part 122 are T ₁₂ ′ and T ₂₂ ′, respectively.

The controller 60 calculates the first temperature gradient V _T1 ′ of the fixing belt 120 at the first heating part 121 from the measured temperatures T ₁₁ ′ and T ₂₁ ′ and measures the measured temperature T _12. The second temperature gradient V _T2 'of the fixing belt 120 is calculated from' and T ₂₂ '(S608).

Thereafter, the control unit 60 compares the first temperature gradient V _T1 ′ of the fixing belt 120 calculated at S608 with the first reference value V _r1 , and the second temperature rising of the fixing belt 120 calculated at S608. The slope V _T2 ′ is compared with the second reference value V _r2 (S610 to S616). Here, the first reference value V _r1 and the second reference value V _r2 may be determined as a first rising slope value and a second rising slope value when the fixing belt 120 operates normally at the rated voltage.

Specifically, the control unit 60 has a first temperature rising slope V _T1 ′ of the fixing belt 120 calculated in S608 is greater than the first reference value V _r1 , and the second temperature rising of the fixing belt 120 calculated in S608. It is determined whether the slope V _T2 ′ is greater than the second reference value V _r2 (S610 and S612).

As a result of the comparison between S610 and S612, when it is determined that the first temperature gradient V _T1 ′ is greater than the first reference value V _r1 and the second temperature gradient V _T2 ′ is greater than the second reference value V _r2 , the controller ( 60 recognizes that the overvoltage higher than the rated voltage is applied to the heat source 130 and displays a guide message on the display unit 80 (S618). In addition, the control unit 60 stores the calculated first temperature gradient V _T1 ′ and the second temperature gradient V _T2 ′ in the memory unit 90, that is, a fixing belt that changes according to various applied voltages ( Compared with the data on the temperature gradient of 120, it is estimated how much higher voltage is applied to the heat source 130 than the rated voltage (S620).

Thereafter, the controller 60 properly controls the duty ratio of the heat source 130 according to the estimated voltage to prevent a problem that may occur when an overvoltage is applied to the heat source 130 (S622).

On the other hand, as a result of comparing S610 and S612, it is determined that the first temperature gradient V _T1 ′ is not greater than the first reference value V _r1 or the second temperature gradient V _T2 ′ is not greater than the second reference value V _r2 . The controller 60 determines whether the first temperature gradient V _T1 ′ is smaller than the first reference value V _r1 and the second temperature gradient V _T2 ′ is smaller than the second reference value V _r2 (S614). , S616).

As a result of the comparison between S614 and S616, when it is determined that the first temperature gradient V _T1 ′ is smaller than the first reference value V _r1 and the second temperature gradient V _T2 ′ is smaller than the second reference value V _r2 , the controller ( 60 recognizes that a low voltage lower than the rated voltage is applied to the heat source 130 and displays a guide message on the display unit 80 (S618). In addition, the controller 60 compares the calculated first temperature gradient V _T1 ′ and the second temperature gradient V _T2 ′ with data stored in the memory unit 90 so that a voltage lower than the rated voltage is a heat source. It is estimated whether it is being applied to (130) (S620).

Then, the controller 60 prevents a problem that may occur when a low voltage is applied to the heat source 130 by appropriately controlling the duty ratio of the heat source 130 according to the estimated voltage (S622).

9 is a cross-sectional view showing the configuration of a fixing device according to another embodiment of the present invention, Figure 10 is a perspective view showing a part of the configuration in the fixing device of FIG. This embodiment relates to an example in which the installation structure of the temperature sensor provided to prevent overheating of the fixing belt is modified.

9 and 10, the fixing device 400 includes a fixing belt 420, a heat source 430, a supporting member 450, a nip forming member 470, a belt guide member 480, and a pressure roller. 440a. Hereinafter, the features of the present embodiment will be described in comparison with the embodiment of FIG. 4.

The supporting member 450 has a reinforcing rib 451 crossing the upper portion of the supporting member 450 in the width direction from the inside of the fixing belt 420. A plurality of connecting ribs 453 are disposed between the reinforcing rib 451 and the support plate 452 to connect them.

Openings 455 are defined between the connecting ribs 453 so that heat radiated to the heat source 430 can pass through the support member 450 as it is.

A temperature sensor 490 is installed outside the fixing belt 420 corresponding to any one of the openings 455. The temperature sensor 490 contacts the outer surface of the fixing belt 420 to measure the temperature of the fixing belt 420. The controller (not shown) of the image forming apparatus controls the heat source 430 based on the temperature of the fixing belt 420 measured by the temperature sensor 490 to prevent overheating of the fixing belt 420.

The temperature sensor 490 may be installed at the center portion in the width direction of the fixing belt 420. The inner surface of the fixing belt 420 is supported by the connecting ribs 453 while the temperature sensor 490 is in contact with the outer surface of the fixing belt 420. Therefore, the temperature sensor 490 may stably contact the fixing belt 420.

Meanwhile, the body portion 470a of the nip forming member 470 has openings 475 corresponding to the openings 455 of the supporting member 450. The heat source 430 may directly radiantly heat the fixing belt 420 through the opening 455 of the support member 450 and the opening 475 of the nip forming member 470.

Degree 11 is a view showing an example in which the light transmitting member is installed in the opening of the support member in the fixing device of FIG.

As illustrated in FIG. 11, a light transmitting member 457 may be installed in the opening 455 of the support member 450 corresponding to the position where the temperature sensor 490 is installed. The light transmitting member 457 allows the heat radiated from the heat source 430 to reach the fixing belt 420 directly, and supports the inner surface of the fixing belt 420 at the portion where the temperature sensor 490 is installed. . In this way, when the light transmitting member 457 is installed in the opening 455, the temperature sensor 490 may be more closely adhered to the outer surface of the fixing belt 420.

The projection 457a is preferably formed at the portion where the light transmitting member 457 contacts the fixing belt 420. This is to minimize the heat loss of the fixing belt 420 by reducing the contact area between the light transmitting member 457 and the fixing belt 420, and to prevent damage to the fixing belt 420 due to friction between the two parts. .

1 is a diagram illustrating a configuration of an image forming apparatus according to an embodiment of the present invention.

2 to 4 is a cross-sectional view, a combined perspective view and an exploded perspective view showing the configuration of the fixing device according to an embodiment of the present invention.

5 is a block diagram illustrating control of a heat source in an image forming apparatus according to an embodiment of the present invention.

6 is a flowchart illustrating a method of controlling a heat source using a first temperature sensor in an image forming apparatus according to an embodiment of the present invention.

7 is a flowchart illustrating a method of determining whether the fixing belt is normally operated using the first temperature sensor and the second temperature sensor in the image forming apparatus according to an embodiment of the present invention.

8 is a flowchart illustrating a method of controlling a heat source using a first temperature sensor and a second temperature sensor when the fixing belt is normally operated in the image forming apparatus according to an embodiment of the present invention.

9 is a cross-sectional view showing the configuration of a fixing apparatus according to another embodiment of the present invention.

10 is a perspective view showing a part of the configuration of the fixing device of FIG.

FIG. 11 is a view illustrating an example in which a light transmitting member is installed in an opening of a support member in the fixing apparatus of FIG. 9; FIG.

* Description of symbols on the main parts of the drawings *

1: image forming apparatus 60: controller

100: fixing device 120: fixing belt

121, 122: heated portion 130: heat source

140: pressure member 150: support member

155: second opening of the support member 170: nip forming member

180: belt guide member 190: first temperature sensor

200: second temperature sensor 210: upper frame

Claims (41)

A fixing belt, a heat source disposed inside the fixing belt, a support member having at least a portion disposed between the heat source and the fixing belt and having an opening formed therethrough so that heat radiated from the heat source can pass therethrough; A fixing device comprising a first temperature sensor for measuring the temperature of the fixing belt in the heating portion of the fixing belt that is directly heated by the radiant heat transmitted; And A controller for controlling the heat source based on the temperature measured by the first temperature sensor; And an image forming apparatus. The method of claim 1, The first temperature sensor is an image forming apparatus, characterized in that for measuring the temperature in contact with the outer surface of the fixing belt. The method of claim 1, The to-be-heated portion includes a print medium contact portion which comes into contact with a print medium passing through the fixing device, and an edge portion which is located outside the print medium contact portion. And the first temperature sensor measures the temperature of the fixing belt at the edge portion. The method of claim 1, And the control unit calculates a temperature gradient of the fixing belt from the temperatures measured by the first temperature sensor and compares the reference value with the reference value to determine whether to cut off the power applied to the heat source. The method of claim 4, wherein And the control unit applies different reference values according to temperatures measured first by the first temperature sensor when comparing the temperature rising slope of the fixing belt with a reference value. The method of claim 1, And the controller cuts off the power applied to the heat source when the temperature measured by the first temperature sensor is equal to or greater than a reference value. The method of claim 1, The fixing device further includes an upper frame disposed on the support member, And the first temperature sensor is installed in the upper frame. The method of claim 7, wherein And the upper frame includes a base plate and a temperature sensor fixing part which extends inclined from the base plate toward the fixing belt. The method of claim 1, The fixing device further comprises a second temperature sensor for measuring the temperature of the fixing belt in the central portion of the fixing belt. The method of claim 9, The second temperature sensor is in contact with the outer surface of the fixing belt, The support member includes a support plate extending in the width direction of the fixing belt, And an inner surface of the fixing belt is supported by the support plate at a portion where the second temperature sensor contacts the fixing belt. The method of claim 9, The fixing device further includes an upper frame disposed on the support member, The first temperature sensor and the second temperature sensor is installed in the upper frame, The upper frame includes a base plate, a first temperature sensor fixing part extending obliquely from the base plate toward the fixing belt, and a second temperature sensor fixing part extending vertically from the base plate toward the fixing belt. An image forming apparatus, characterized in that. The method of claim 1, The support member includes at least two ribs, The first temperature sensor is in contact with the outer surface of the fixing belt to measure the temperature of the fixing belt, And the inner surface of the fixing belt is supported by the ribs at a portion where the first temperature sensor contacts the fixing belt. The method of claim 12, And a translucent member in an opening defined between the ribs. The method of claim 13, And the light transmitting member protrudes toward the fixing belt and includes a protrusion contacting an inner surface of the fixing belt. The method of claim 1, The fixing device further includes a pressing member for forming a fixing nip facing the fixing belt, and a nip forming member for supporting an inner surface of the fixing belt to form a fixing nip together with the pressing member. And the nip forming member includes an opening formed at an opposite side of the fixing nip so that heat radiated from the heat source can pass therethrough. A fixing device having a heat source, a fixing belt having a heated portion directly radiated by the heat source, and a first temperature sensor which measures a temperature of the fixing belt by contacting an outer surface of the fixing belt at the heated portion. ;Wow A control unit for turning off the heat source when the temperature rising slope of the fixing belt calculated from the temperatures measured by the first temperature sensor is equal to or greater than a reference value; And an image forming apparatus. A fixing belt having a heat source generating heat, a first heated portion directly heated by radiant heat of the heat source, and a second heated portion indirectly heated by heat transferred from the heat source, and a first of the fixing belt A fixing device including a first temperature sensor for measuring a temperature of the fixing belt at a heated portion and a second temperature sensor for measuring a temperature of the fixing belt at a second heated portion of the fixing belt; A control unit controlling an operation of the heat source according to the temperature of the fixing belt measured by the first temperature sensor and the second temperature sensor; Image forming apparatus comprising a. The method of claim 17, And at least one member disposed on a path through which the heat of the heat source is transferred to the fixing belt. The method of claim 18, And the at least one member includes an opening to allow heat radiated from the heat source to pass through the member to directly heat the first heated portion of the fixing belt. The method of claim 18, And the at least one member prevents heat radiated from the heat source from directly heating the second heated portion of the fixing belt. The method of claim 17, The first temperature sensor and the second temperature sensor is an image forming apparatus, characterized in that for measuring the temperature of the fixing belt at different positions in the rotation direction of the fixing belt. The method of claim 17, And the first temperature sensor and the second temperature sensor measure the temperature of the fixing belt at different positions in the width direction of the fixing belt. The method of claim 17, The fixing belt forms a pressing member and a fixing nip which are installed to face the fixing belt, And the second temperature sensor measures a temperature of the fixing belt near the fixing nip. The method of claim 17, The at least one member includes a support member at least partially disposed between the heat source and the fixing belt, And the support member has an opening to allow heat radiated from the heat source to pass through the support member to directly heat the first heated portion of the fixing belt. The method of claim 17, Further comprising; a pressing member facing the fixing belt, A nip forming member disposed between the heat source and the fixing belt and supporting the inner surface of the fixing belt to form a fixing nip between the outer surface of the fixing belt and the pressing member, And the nip forming member includes an opening to direct heat radiated from the heat source to pass through the nip forming member to directly heat the first heated portion of the fixing belt. The method of claim 17, The control unit determines a first temperature rising slope of the fixing belt from temperatures measured at time intervals in the first temperature sensor, and measures the first temperature of the fixing belt from temperatures measured at time intervals in the second temperature sensor. And determining a second heating gradient, and comparing the first heating gradient and the second heating gradient with a first reference value and a second reference value, respectively. The method of claim 26, And the controller cuts off the power applied to the heat source when the first temperature rising slope is greater than the first reference value and the second temperature rising slope is less than the second reference value. The method of claim 26, The controller determines whether an overvoltage or a low voltage is applied to the heat source based on a result of comparing the first elevated temperature gradient with the first reference value and a result of comparing the second elevated temperature gradient with the second reference value. Image forming apparatus. The method of claim 28, And when the controller determines that an overvoltage or undervoltage is applied to the heat source, the controller adjusts a duty ratio of the heat source. Fixing belt; and A heat source disposed in the fixing belt; and A pressing member forming a fixing nip opposite the fixing belt; and A nip forming member supporting an inner surface of the fixing belt to form a fixing nip together with the pressing member, and an opening formed so that heat radiated from the heat source can directly heat the fixing belt; A support member disposed outside the nip forming member and formed with an opening so that heat radiated from the heat source can directly heat the fixing belt; and And a first temperature sensor measuring a temperature of the fixing belt at a position corresponding to the opening of the nip forming member and the opening of the supporting member. The method of claim 30, At least one of the nip forming member and the support member includes a blocking portion that prevents radiant heat of the heat source from being directly transmitted to the fixing belt, The fixing device further comprises a second temperature sensor for measuring the temperature of the fixing belt in a portion where the radiant heat of the heat source is not directly transmitted by the blocking unit. In the control method of the fixing device comprising a fixing belt disposed around the heat source, First measuring a temperature of a portion to be heated directly heated by radiant heat of the heat source in the fixing belt; Measuring the temperature of the portion to be heated of the fixing belt for a second time; Determining a temperature rising slope of the fixing belt from the first measured temperature and the second measured temperature; Comparing the temperature gradient with a reference value; And controlling the operation of the heat source based on a result of comparing the temperature gradient with the reference value. 33. The method of claim 32, And selecting any one of a plurality of values as the reference value based on the first measured temperature in the heated portion. 33. The method of claim 32, Determining that an error has occurred when the temperature rising slope is equal to or greater than the reference value; Count the number of times the error occurred; Determine whether the number of error occurrences is equal to a reference number; And cutting off the power applied to the heat source when the number of occurrences of the error is equal to a reference number of times. In the control method of the fixing device comprising a fixing belt disposed around the heat source, Firstly measuring the temperature of the first heated portion directly heated by the radiant heat of the heat source in the fixing belt and the temperature of the second heated portion indirectly heated by the heat transferred from the heat source in the fixing belt; Secondly measuring the temperature of the first heated portion and the temperature of the second heated portion; Determining a temperature rising slope of the first heated portion from the first measured temperature and the second measured temperature in the first heated portion; Determining a temperature gradient of the second heated portion from the first measured temperature and the second measured temperature in the second heated portion; And comparing the temperature rising slope of the first heated portion with a first reference value and comparing the temperature rising slope of the second heated portion with a second reference value. 36. The method of claim 35 wherein And controlling the operation of the heat source according to a result of comparing the temperature gradients with a reference value. The method of claim 36, The control method of the fixing apparatus, characterized in that the power applied to the heat source is cut off when the temperature rising slope of the first heated portion is greater than the first reference value and the temperature rising slope of the second heated portion is less than the second reference value. . The method of claim 36, If the temperature rising slope of the first heated portion is greater than the first reference value and the temperature rising slope of the second heated portion is greater than the second reference value, it is determined that an overvoltage is applied to the heat source. . The method of claim 36, When the temperature rising slope of the first heated portion is smaller than the first reference value and the temperature rising slope of the second heated portion is smaller than the second reference value, it is determined that a low voltage is applied to the heat source. Control method. The method of claim 36, And controlling the duty ratio of the heat source according to a result of comparing the temperature gradients with a reference value. 36. The method of claim 35 wherein And displaying information on the operation of the fixing device in a display unit according to a result of comparing the temperature gradients with a reference value.

Images