JP7447646B2 - Image forming device - Google Patents

Description

The present invention relates to an image forming apparatus.

Conventionally, image forming apparatuses have been known that are equipped with an image forming section that forms an image by applying toner to paper, and a fixing device that fixes the image to the paper by passing the paper with the image attached thereon and applying heat and pressure. It is being The fixing device may include one that heats and presses the paper at the nip portion of a pair of rollers that includes a heating roller with a built-in heating means, or one that heats and presses the paper at the nip portion of a pair of rollers, or one that heats and presses the paper through a fixing belt stretched around the heating roller. There is something that pressures me. The fixing device is provided with a temperature detection means, and lighting control of the heating means is performed based on the temperature detected by the temperature detection means.

By the way, if the temperature detection means does not accurately detect the temperature of the fixing components such as the heating roller or the fixing belt, defective fixing temperature control will occur, resulting in problems such as poor paper feeding, poor images, and even damage to the fixing components. occurs.
For example, Patent Document 1 states that when a non-contact temperature sensor such as a thermopile is used as a temperature detection means, if the infrared receiving part becomes dirty due to some external cause, the temperature detection will not work properly. Compares the temperature difference between the temperature and the ambient temperature of the environment in which the rotating body is installed, and when the temperature difference is equal to or higher than a preset temperature, it determines that the detection part of the temperature detection means is dirty and notifies the user. The technology is described.

In addition, the fixing device is equipped with a plurality of temperature detection means, and when the difference between the temperatures detected by the plurality of temperature detection means exceeds a predetermined value, it is determined that the temperature detected by the temperature detection means is abnormal. .

Japanese Patent Application Publication No. 2007-41306

However, in the technique described in Patent Document 1, it takes 10 minutes or more from when the thermopile detects the temperature to when it makes a determination. Therefore, the heating means continues to be lit during that time, leading to damage to the fixing component.
In addition, in the technology that determines an abnormality based on whether the difference between the detected temperatures of multiple temperature detection means is greater than or equal to a predetermined value, it is possible to In order to take into account the temperature setting variation range (for example, ±20° C.) depending on the paper size and the paper size, it cannot be determined that there is an abnormality unless there is a difference of at least 50° C. or more. Therefore, the fixing component may already be damaged by the time it is determined that there is an abnormality.

SUMMARY OF THE INVENTION An object of the present invention is to enable early determination of abnormalities in the detection results of the temperature detection means, and to reduce problems such as poor paper feeding, poor images, and damage to fixing components.

In order to solve the above problems, the invention according to claim 1,
An image forming apparatus comprising a fixing unit that fixes an image formed on the recording medium by passing the recording medium between a pair of rotating bodies,
heating means for heating at least one of the rotating bodies;
a plurality of temperature detection means arranged at different positions and configured to detect the temperature of the rotating body heated by the heating means;
The temperature difference between the plurality of temperature detection means is compared with the temperature difference between the plurality of temperature detection means in the past, and if the difference between the two exceeds a predetermined value, the temperature difference between the plurality of temperature detection means is determined. a control means for determining that there is an abnormality in the detection result of any of the detection means;
Equipped with

The invention according to claim 2 is the invention according to claim 1,
At least one of the plurality of temperature sensing means is a non-contact type temperature sensing means.

The invention according to claim 3 is the invention according to claim 1 or 2,
The plurality of temperature sensing means are arranged at different positions in the axial direction of the rotating body.

The invention according to claim 4 is the invention according to claim 3,
The control means compares a temperature difference detected between the plurality of temperature detection means with a temperature difference detected between the plurality of temperature detection means when the operating state of the fixing section was the same in the past.

The invention according to claim 5 is the invention according to claim 4,
The control means compares the temperature difference when paper is not passed.

The invention according to claim 6 is the invention according to claim 1 or 2,
The plurality of temperature sensing means are arranged at the same position in the axial direction of the rotary body, but at different positions in the rotational direction of the rotary body.

The invention according to claim 7 is the invention according to any one of claims 1 to 6,
At least one of the rotating bodies is an endless belt.

The invention according to claim 8 is the invention according to any one of claims 1 to 7,
The control means determines that there is an abnormality when the difference exceeds the predetermined value for a predetermined time or more.

The invention according to claim 9 is the invention according to any one of claims 1 to 8,
A notification means is provided for notifying a user of the abnormality when it is determined that there is an abnormality in the detection result of any of the plurality of temperature sensing means.

According to the present invention, abnormalities in the detection results of the temperature detection means can be determined at an early stage, so that problems such as poor paper feeding, poor images, and damage to fixing components can be reduced.

1 is a diagram showing a schematic configuration of an image forming apparatus. 1 is a block diagram showing the main functional configuration of an image forming apparatus. FIG. 3 is a schematic diagram showing the configuration of a fixing unit in which a plurality of temperature detection units are arranged at different positions in the axial direction of the fixing belt. (a) is a front view of the fixing unit when a jam occurs, and (b) is a side view of the fixing unit when a jam occurs. 3 is a flowchart showing the flow of abnormality detection processing executed by the control unit in FIG. 2. FIG. FIG. 7 is a diagram illustrating predetermined values for each operating state of the fixing unit, which are used when a plurality of temperature detection units are arranged at different positions in the axial direction of the fixing belt. FIG. 3 is a schematic diagram showing the configuration of a fixing unit in which a plurality of temperature detection units are arranged at different positions in the rotational direction of the fixing belt. FIG. 7 is a diagram illustrating predetermined values for each operating state of the fixing unit, which are used when a plurality of temperature detection units are arranged at different positions in the rotational direction of the fixing belt.

Hereinafter, this embodiment will be described in detail based on the drawings. However, the scope of the invention is not limited to the illustrated example.

FIG. 1 is a diagram showing a schematic configuration of an image forming apparatus 1 according to an embodiment of the present invention. FIG. 2 is a block diagram showing the main functional configuration of the image forming apparatus 1. As shown in FIG.

The image forming apparatus 1 includes a control unit 10 having a CPU 101 (Central Processing Unit), a RAM 102 (Random Access Memory), and a ROM 103 (Read Only Memory), a storage unit 11, an operation unit 12, a display unit 13, an interface 14, a scanner 15, It includes an image processing section 16, an image forming section 17, a fixing section 18, a conveyance section 19, and the like. The control unit 10 is connected to a storage unit 11, an operation unit 12, a display unit 13, an interface 14, a scanner 15, an image processing unit 16, an image forming unit 17, a fixing unit 18, and a transport unit 19 via a bus 21. .

The CPU 101 reads and executes a control program stored in the ROM 103 or the storage unit 11, and performs various calculation processes.

The RAM 102 provides a working memory space for the CPU 101 and stores temporary data.

The ROM 103 stores various control programs executed by the CPU 101, setting data, and the like. Note that in place of the ROM 103, a rewritable nonvolatile memory such as an EEPROM (Electrically Erasable Programmable Read Only Memory) or a flash memory may be used.

The control unit 10 including the CPU 101, RAM 102, and ROM 103 centrally controls each unit of the image forming apparatus 1 according to the various control programs described above. For example, the control unit 10 executes a job based on a job execution command. That is, the control unit 10 causes the image processing unit 16 to perform predetermined image processing on the image data and stores it in the storage unit 11. The control unit 10 also causes the transport unit 19 to transport the paper, causes the image forming unit 17 to form an image on the paper based on the image data stored in the storage unit 11, and causes the fixing unit 18 to fix the image on the paper. . Further, the control unit 10 controls the lighting of the heating means 182 based on the detection result of the temperature detection unit 186. Further, while the power is on, the control unit 10 executes an abnormality detection process to be described later, and determines whether the detection result of the temperature detection unit 186 in the fixing unit 18 is abnormal.

The storage unit 11 is composed of a DRAM (Dynamic Random Access Memory) or the like, and stores image data acquired by the scanner 15, image data input from the outside via the interface 14, and the like. Note that these image data and the like may be stored in the RAM 102.
The storage unit 11 includes a temperature detection result storage unit 111 for storing temperature differences (absolute values) of the detection results of the plurality of temperature detection units 186.

The operation unit 12 includes input devices such as operation keys and a touch panel placed over the screen of the display unit 13 , converts input operations on these input devices into operation signals, and outputs the signal to the control unit 10 .

The display unit 13 includes a display device such as an LCD (Liquid Crystal Display), and displays an operation screen showing the status of the image forming apparatus 1 and the contents of input operations on the touch panel.

The interface 14 is a means for transmitting and receiving data with an external computer, other image forming apparatus, etc., and is configured by, for example, one of various serial interfaces.

The scanner 15 reads the image formed on the paper, generates image data including monochromatic image data for each color component of R (red), G (green), and B (blue), and stores the image data in the storage unit 11.

The image processing section 16 includes, for example, a rasterization processing section, a color conversion section, a gradation correction section, and a halftone processing section, and performs various image processing on the image data stored in the storage section 11 and stores the image data in the storage section 11.

The image forming section 17 forms an image on paper based on the image data stored in the storage section 11. The image forming section 17 includes four sets of exposing sections 171, photoreceptors 172, and developing sections 173, each corresponding to the color components of C (cyan), M (magenta), Y (yellow), and K (black). . Further, the image forming section 17 includes a transfer body 174 and a secondary transfer roller 175.

The exposure section 171 includes an LD (Laser Diode) as a light emitting element. Exposure section 171
drives the LD based on image data, irradiates and exposes the charged photoreceptor 172 with laser light, and forms an electrostatic latent image on the photoreceptor 172. The developing section 173 supplies toner (coloring material) of a predetermined color (any of C, M, Y, and K) using a developing roller that charges the exposed photoconductor 172 to form a toner on the photoconductor 172. Develop the electrostatic latent image.
Images (single-color images) formed with C, M, Y, and K toners on the four photoreceptors 172 corresponding to C, M, Y, and K are sequentially superimposed from each photoreceptor 172 onto the transfer member 174. and transcribed. As a result, a color image having C, M, Y, and K as color components is formed on the transfer body 174. The transfer body 174 is an endless belt wound around a plurality of transfer body conveyance rollers, and rotates according to the rotation of each transfer body conveyance roller.
The secondary transfer roller 175 transfers the color image on the transfer body 174 onto a sheet of paper fed from the paper feed tray 22 or an external paper feed device. Specifically, by applying a predetermined transfer voltage to the secondary transfer roller 175 that sandwiches the paper and the transfer body 174, the toner forming the color image on the transfer body 174 is drawn toward the paper side and transferred to the paper. The image is transferred.

The fixing unit 18 performs a fixing process of fixing the image onto the paper by heating and pressurizing the paper onto which the image has been transferred.

The transport unit 19 includes a plurality of paper transport rollers that transport the paper by rotating while holding the paper between them, and transports the paper along a predetermined transport path. The transport unit 19 includes a reversing mechanism 191 that reverses the front and back of the paper that has been subjected to the fixing process by the fixing unit 18 and transports the paper to the secondary transfer roller 175 . In the image forming apparatus 1, when forming images on both sides of a sheet, the reversing mechanism 191 reverses the sheet, and after forming images on both sides, the sheet is ejected to the sheet ejection tray 23. When an image is formed on only one side of the paper, the paper with the image formed on one side is ejected to the paper ejection tray 23 without the reversing mechanism 191 inverting the paper.

The fixing section 18 will be explained in detail below.
FIG. 3 is a schematic diagram showing the configuration of the fixing section 18. As shown in FIG. 3, the fixing unit 18 includes a heating roller 181 having a heating means 182, an upper pressure roller 183, and an endless belt stretched between the heating roller 181 and the upper pressure roller 183. The fixing belt 184 (rotating body), a lower pressure roller 185 (rotating body), and a temperature detecting section 186 are provided. The longitudinal direction (axial direction) of each component of the fixing unit 18 is the x direction shown in FIG. The heating roller 181 to the fixing belt 184 and the temperature detection unit 186 are provided on the fixing surface side of the paper being conveyed, and the lower pressure roller 185 is arranged opposite to the fixing belt 184 across the conveyance path 192 (i.e., (on the back side of the paper). A heating means for heating the lower pressure roller 185 may be provided.

The lower pressure roller 185 is configured to be movable, and the upper pressure roller 183 and the lower pressure roller 185 can be pressed and separated by driving a pressure-bonding drive mechanism (not shown). By pressing and separating the upper pressure roller 183 and the lower pressure roller 185, the fixing belt 184 and the lower pressure roller 185 can be pressed and separated. When the fixing belt 184 and the lower pressure roller 185 are pressed together and rotated, a fixing nip is formed in which the paper on which the image is formed is sandwiched and conveyed. When the paper passes through a fixing nip formed by a fixing belt 184 heated by a heating means 182 and a lower pressure roller 185, it is heated and pressurized, and the toner image is fixed on the paper.

The heating means 182 is constituted by one or more heaters constituted by a halogen lamp, a resistance heating element, IH (induction heating), or the like. The present embodiment will be described using an example in which the heating means 182 is constituted by four halogen lamp heaters.

The heating unit 182 heats the fixing belt 184, and includes, for example, a central heater 182a, a central heater 182b, an end heater 182c, and an end heater 182d. The central heaters 182a and 182b are heaters for heating the central portion of the fixing belt 184 in the axial direction. The end heaters 182c and 182d are heaters for heating both ends of the fixing belt 184 in the axial direction. The end heaters 182c and 182d are used depending on the width of the paper used. When the width of the paper is smaller than B4 size, the edge heater 182c is used, and when it exceeds B4 size, the edge heater 182d is used.
Note that the number of heaters provided in the heating means 182 is an example, and is not particularly limited.

The temperature detection section 186 is provided at the center of the fixing belt 184 in the axial direction, and includes a first temperature detection section 186a that detects the temperature of the center section of the fixing belt 184, and a first temperature detection section 186a that is provided at the end of the fixation belt 184 in the axial direction. , a second temperature detection section 186b for detecting the temperature at the end of the fixing belt 184 (see FIG. 4B).
As the temperature detection section 186, for example, a thermistor or the like can be used. Since the fixing belt 184 is a fixing component that comes into direct contact with the image surface, it is preferable to use a non-contact type as the temperature detection section 186.

The temperature detection section 186 is connected to the control section 10. The control unit 10 controls the temperature of the center portion of the fixing belt 184 to reach the target temperature by controlling the lighting of the central heaters 182a and 182b based on the detection result of the first temperature detection unit 186a. Furthermore, the control unit 10 controls the lighting of the end heaters 182c and 182d based on the detection result of the second temperature detection unit 186b, so that the temperature at the end of the fixing belt 184 reaches the target temperature. Control.
Note that it is preferable to control the lighting of each heater of the heating means 182 by duty control (HCD (Half Cycle Duty) control) rather than ON/OFF control because the temperature is more stable.

Here, FIG. 4(a) shows a front view of the fixing unit 18 when a jam occurs. FIG. 4B shows a side view (right side view) of the fixing unit 18 when a jam occurs. As shown in FIG. 4(a), if a jam occurs due to paper being wrapped around the fixing belt 184, the jammed paper remains inside the fixing unit 18 without being visible to the user. Sometimes. In this case, if the residual paper RP blocks the gap between the non-contact temperature detection unit 186 and the fixing belt 184, the temperature of the fixing belt 184 will not be detected correctly (it will be detected lower than the actual temperature, temperature is controlled to be higher than the target), fusing temperature control may be poor, resulting in poor paper feeding (paper wrapping, etc.), image defects (such as glossiness being higher than intended), and even fusing. The belt 184 etc. may be damaged. Therefore, conventionally, as shown in FIG. 4B, a plurality of temperature detection sections (a first temperature detection section 186a, a second temperature detection section 186b) are provided in the axial direction of the fixing belt 184, and the detected temperatures are If the temperature difference exceeds a predetermined value, it is determined that there is an abnormality. However, in this case, it is necessary to consider all situations, so as mentioned above, the temperature difference must be set to at least 50 degrees Celsius, and the fixing belt 184 etc. are already in use by the time an abnormality is determined. Sometimes it got damaged.

Therefore, in the present embodiment, the control unit 10 performs the abnormality detection process shown in FIG. The temperature (or temperature difference) is periodically stored in the storage unit 11, the temperature difference between the first temperature detection unit 186a and the second temperature detection unit 186b is compared with the past temperature difference, and based on the comparison result, Determine whether there is an abnormality in the detected temperature.

FIG. 5 shows the flow of the abnormality detection process. The abnormality detection process is executed in cooperation with the CPU 101 of the control unit 10 and a program stored in the ROM 103.

First, the control unit 10 acquires the detected temperatures of the plurality of temperature detection units 186 (the first temperature detection unit 186a and the second temperature detection unit 186b; the same applies hereinafter) (step S1).

Next, the control unit 10 calculates the temperature difference (absolute value) between the detection results of the plurality of temperature detection units 186, and stores it in the temperature detection result storage unit 111 of the storage unit 11 (step S2).
For example, the control unit 10 may calculate the calculated temperature difference based on the operational status of the fixing unit 18 (for example, warming up, idling, passing paper (large size (a predetermined size or more)), paper passing (small size (less than a predetermined size)), )) and date and time and are stored in the temperature detection result storage unit 111. Note that the large size and small size represent the size of the paper used.
In this embodiment, the case where the temperature detection section 186 is composed of two, the first temperature detection section 186a and the second temperature detection section 186b, is explained as an example, but it is also possible that the temperature detection section 186 is composed of three or more. You can leave it there. In this case, for example, the temperature difference (absolute value) between two temperature sensing units is calculated and their representative values (average value, median value, maximum value, etc.) are calculated based on the detection results of the plurality of temperature sensing units 186. It may also be a temperature difference.

Next, the control unit 10 determines whether a jam has occurred in the fixing unit 18 (step S3).
Whether or not a jam has occurred in the fixing unit 18 can be determined, for example, by providing sensors on the upstream and downstream sides of the fixing unit 18 on the conveyance path 192, and determining whether a jam has occurred on the downstream side within a predetermined time after the upstream sensor detects the paper. If the sensor does not detect paper (or if it continues to detect paper for a predetermined period of time), it is determined that a jam has occurred.

If it is determined that no jam has occurred in the fixing unit 18 (step S3; NO), the control unit 10 refers to the temperature detection result storage unit 111 and calculates the temperature difference between the temperatures detected by the plurality of temperature detection units 186. A comparison is made with the temperature difference (past temperature difference) when the fixing unit 18 was in the same operating state in the past (step S4).
For example, the control unit 10 compares the temperature difference calculated in step S2 with the temperature difference between the plurality of temperature detection units 186 when the fixing unit 18 was in the same operating state in the past, which is stored in the temperature detection result storage unit 111. compare. Specifically, the difference (absolute value) between the temperature difference calculated in step S2 and the temperature difference when the fixing unit 18 was in the same operating state in the past is calculated.

Next, the control unit 10 determines whether the difference from the calculated past temperature difference exceeds a predetermined value (step S5).
The predetermined value here is a value that serves as a reference for determining whether or not there is an abnormality in the detection result of the first temperature detection section 186a or the second temperature detection section 186b, and is experimentally determined. It is stored in the storage unit 11 in advance.

FIG. 6 is a diagram showing an example of predetermined values stored in the storage unit 11. When a plurality of temperature detection sections 186 are provided in the axial direction of the fixing belt 184 as in the present embodiment, each temperature detection section may Since there are errors (unevenness) in the detected temperature, the predetermined value is set taking these into consideration. In addition, during paper passing, the magnitude of the influence of paper passing varies depending on whether each temperature detection part is within the paper passing range, and the influence also differs depending on the basis weight of the paper and storage conditions. (during idling) is set to a larger predetermined value.
Note that if the difference exceeds the predetermined value even for a moment, it is determined to be abnormal, and false detections due to noise etc. will also be included. It is preferable to judge that the situation is abnormal.

In step S5, if it is determined that the difference from the past temperature difference does not exceed the predetermined value (step S5; NO), the control unit 10 returns to step S1.

If it is determined that the difference from the past temperature difference exceeds the predetermined value (step S5; YES), the control unit 10 controls the temperature of either the first temperature detection unit 186a or the second temperature detection unit 186b. It is determined that the detection result is abnormal, a notification indicating that there is an abnormality (there is residual paper RP) is displayed on the display unit 13 (step S6), and the process moves to step S10.
For example, if two sheets of paper are fed at once and reach the fixing section 18 during paper feeding, one sheet gets wrapped around the fixing belt 184 and the other sheet comes out of the fixing section 18, a jam occurs in step S3. is not determined, and the job may be continued with the residual paper RP remaining in the fixing unit 18. In steps S5 and S6, it is possible to detect an abnormality in the detection result of the first temperature detection section 186a or the second temperature detection section 186b due to the residual paper RP that is not determined to be a jam.

In step S10, the control unit 10 determines whether the remaining paper RP has been removed (step S10). For example, if the difference in temperature detected by the first temperature detection section 186a and the second temperature detection section 186b is less than a predetermined threshold value, it is determined that the remaining paper RP has been removed.
If it is determined that the remaining paper RP has been removed (step S10; YES), the control unit 10 returns to step S1. The control unit 10 repeatedly executes the processes from step S1 to step S10 while the image forming apparatus 1 is powered on.

On the other hand, if it is determined in step S3 that a jam has occurred (step S3; YES), the control unit 10 refers to the temperature detection result storage unit 111 and calculates the difference in detected temperatures between the plurality of temperature detection units 186. A comparison is made before and after the jam occurs (step S7).
For example, when a jam occurs in the fixing unit 18, the control unit 10 displays guidance on the display unit 13 to instruct the user to remove the jammed paper. The user looks at the guidance, opens the front door of the image forming apparatus 1, and removes the paper from the fixing section 18. For example, when detecting that the fixing section 18 has been returned to its original position and determining that the user's work has been completed, the control section 10 shifts to a warm-up state and detects the temperature of the plurality of temperature detection sections 186. The detected temperature (detected temperature after the jam occurs) is acquired, the temperature difference is calculated, and compared with the temperature difference in the warm-up state before the jam occurs, which is stored in the temperature detection result storage unit 111. Specifically, the difference in temperature before and after the jam occurs is calculated.

Next, the control unit 10 determines whether the difference in temperature (absolute value) between the plurality of temperature detection units 186 before and after the occurrence of the jam exceeds a predetermined value (step S8).
The predetermined value here is a value that serves as a reference for determining whether or not there is an abnormality in the detection result of the first temperature detection section 186a or the second temperature detection section 186b, and is, for example, determined experimentally. This value is stored in advance in the storage unit 11 for each operating state of the fixing unit 18 (see FIG. 6).

For example, as shown in FIGS. 4(a) and 4(b), if a jammed sheet of paper remains between the first temperature detection unit 186a and the fixing belt 184, it is blocked by the remaining sheet of paper RP. The temperature detected by the first temperature detection section 186a is lower than the actual temperature of the fixing belt 184. Therefore, the difference in temperature detected by the first temperature detection section 186a and the second temperature detection section 186b becomes larger than before the jam occurs. Therefore, the control unit 10 determines that residual paper RP exists in the fixing unit 18 when the difference in temperature between the plurality of temperature detection units before and after the occurrence of a jam exceeds a predetermined value.

If it is determined that the difference in temperature between the plurality of temperature detection units before and after the jam occurs does not exceed the predetermined value (step S8; NO), the control unit 10 returns to step S1.

If it is determined that the difference in temperature between the plurality of temperature detection units before and after the occurrence of a jam exceeds a predetermined value (step S8; YES), the control unit 10 controls whether the first temperature detection unit 186a or the second temperature detection unit 186b is determined to be abnormal (that is, a fixing control failure has occurred), and displays a notification indicating the abnormality (that there is residual paper RP) on the display unit 13 (step S9), the process moves to step S10.
Here, as described above, the predetermined value is smaller when paper is not passing than when paper is passing, so in step S7, the temperature difference calculated in the warm-up state before the jam occurs and the temperature difference in the warm-up state after the jam occurs. By comparing the temperature difference between the two temperatures, it is possible to determine an abnormality based on a small temperature difference.

In step S10, the control unit 10 determines whether the remaining paper RP has been removed (step S10). For example, when the difference in temperature detected by the first temperature detection section 186a and the second temperature detection section 186b is less than a predetermined threshold value, it is determined that the remaining paper RP has been removed.
If it is determined that the remaining paper RP has been removed (step S10; YES), the control unit 10 returns to step S1. The control unit 10 repeatedly executes the processes from step S1 to step S10 while the image forming apparatus 1 is powered on.

In the image forming apparatus 1 of the embodiment described above, the temperature difference between the detected temperatures of the plurality of temperature detecting sections 186 disposed at different positions in the axial direction of the fixing belt 184 is measured in the past when the operating state of the fixing section 18 is the same. When the difference between the two exceeds a predetermined value, it is determined that there is an abnormality in the detection result of one of the plurality of temperature detection units.
Therefore, compared to conventional methods, the predetermined value for determining an abnormality can be significantly reduced, making it possible to determine defects in fixing temperature control at an early stage. The goal is to reduce the number of defects.

(Modified example)
In the above embodiment, as shown in FIG. 4B, a plurality of temperature sensing units 186 are arranged at different positions in the axial direction of the fixing belt 184. However, as shown in FIG. A plurality of temperature detection units 186 may be arranged in the same axial direction but at different positions in the rotational direction of the fixing belt 184, and abnormality detection processing may be similarly performed to detect an abnormality. In this case, if there is no abnormality, the temperatures of the plurality of temperature detection units 186 will be almost the same regardless of the operating state of the fixing unit 18, so the predetermined values used in steps S5 and S8 may be as small as possible; There is no need to provide different predetermined values depending on the operating state of the fixing section 18. FIG. 8 shows an example of the predetermined values when a plurality of temperature detection units are arranged in the same axial direction of the fixing belt 184 but at different positions in the rotational direction of the fixing belt 184. Further, the past temperature difference to be compared with the current temperature difference between the plurality of temperature detection units 186 does not need to be limited to the temperature difference when the operating state of the fixing unit 18 is the same. Therefore, it becomes possible to detect an abnormality earlier.
Furthermore, a configuration in which a plurality of sets of temperature detection units are provided in the axial direction of the fixing belt 184, which are arranged in the same axial direction of the fixing belt 184 but at different positions in the rotating direction of the fixing belt 184, can be used to similarly perform abnormality detection processing. May be implemented. Thereby, the accuracy of abnormality detection can be improved.

As described above, according to the image forming apparatus 1, the control section 10 is arranged at different positions, and is arranged between the plurality of temperature detection sections 186 for detecting the temperature of the fixing belt 184 and the plurality of temperature detection sections 186. The temperature difference between the detected temperatures of the plurality of temperature detection sections 186 of the plurality of temperature detection sections 186 of the plurality of temperature detection sections 186 of the plurality of temperature detection sections 186 of the fixing section 18 is compared with the temperature difference of the detection temperatures of the plurality of temperature detection sections 186 of the past fixing section 18 when the difference between the two exceeds a predetermined value. It is determined that there is an abnormality in one of the detection results.
Therefore, since the predetermined value for determining an abnormality can be made significantly smaller than in the past, abnormalities in the detection results of the temperature detection section 186 can be determined early, and paper feeding failures, image failures, Problems such as damage to fixing components can be reduced.

Further, for example, if at least one of the plurality of temperature detection units 186 is a non-contact type temperature detection unit, abnormalities such as residual paper RP entering between the temperature detection unit 186 and the fixing belt 184 are likely to occur. , an abnormality in the detection result of the temperature detection unit 186 due to such an abnormality can be determined at an early stage.

Further, for example, if a plurality of temperature detection units 186 are arranged at different positions in the axial direction of the fixing belt 184, the temperature difference between the detected temperatures between the plurality of temperature detection units 186 may be calculated based on the past operating state of the fixing unit 18. By comparing the detected temperatures between the plurality of temperature detecting sections 186 when the temperature is the same, abnormality in the detection result of the temperature detecting section 186 can be determined at an early stage. In particular, by comparing the temperatures when paper is not passing, it is possible to determine an abnormality even with a small temperature difference, and it is possible to determine an abnormality more quickly.

Further, for example, by arranging a plurality of temperature detection units 186 at the same position in the axial direction of the fixing belt 184 but at different positions in the rotational direction of the fixing belt 184, it is possible to determine whether or not there is an abnormality. Since the predetermined value can be made even smaller, an abnormality in the detection result of the temperature detection section 186 can be determined earlier.

Further, by determining that an abnormality is occurring when the difference from the past temperature difference exceeds a predetermined value for a predetermined period of time or longer (for example, one second or longer), false detection due to noise or the like can be prevented.

Furthermore, if it is determined that there is an abnormality in the detection result of any of the plurality of temperature detection units 186, the user is notified of the abnormality, so that the user can recognize the abnormality and take appropriate action. It becomes possible to do so.

Note that the description in the above embodiments and modified examples is a preferred example of the image forming apparatus according to the present invention, and the present invention is not limited thereto.
For example, in the embodiment described above, the abnormality determination of the temperature detection unit 186 is always performed, but it may be performed only when a jam occurs.

Further, for example, in the above embodiments and modified examples, the case where the fixing section 18 is configured to use the fixing belt 184 has been explained as an example, but in the present invention, the fixing section 18 does not use the fixing belt, but instead uses the heating roller and the lower pressure roller. The present invention may be applied to a fixing unit configured to directly press the fixing member. Alternatively, a fixing belt may also be provided on the lower pressure roller side.

Furthermore, in the embodiment described above, the image forming apparatus 1 is a color image forming apparatus that sequentially transfers toner images on a photoreceptor to a transfer member, but a plurality of image carriers for each color are transferred onto an intermediate transfer member. It may be a tandem type color image forming apparatus arranged in series, or it may be a monochrome image forming apparatus that forms an image using a single color toner.

Furthermore, in the above embodiments, paper is used as the recording medium. However, the recording medium may include paper such as plain paper or coated paper, as well as cloth or sheet-like resin, etc. Various media capable of fixing the coloring material can be used.

Further, in the above description, an example has been disclosed in which an HDD or a semiconductor memory is used as a computer-readable medium for the program according to the present invention, but the present invention is not limited to this example.
As other computer-readable media, nonvolatile memories such as flash memories, and portable recording media such as CD-ROMs can be used.
Further, a carrier wave is also applied to the present invention as a medium for providing data of the program according to the present invention via a communication line.

In addition, the detailed configuration and detailed operation of the image forming apparatus can be changed as appropriate without departing from the spirit of the present invention.

1 Image forming apparatus 10 Control section 11 Storage section 111 Temperature detection result storage section 12 Operation section 13 Display section 14 Interface 15 Scanner 16 Image processing section 17 Image forming section 18 Fixing section 181 Heating roller 182 Heating means 182a Central heater 182b Central heater 182c End heater 182d End heater 183 Upper pressure roller 184 Fixing belt 185 Lower pressure roller 186 Temperature detection section 186a First temperature detection section 186b Second temperature detection section 19 Conveyance section 21 Bus

Claims (9)

An image forming apparatus comprising a fixing unit that fixes an image formed on the recording medium by passing the recording medium between a pair of rotating bodies,
heating means for heating at least one of the rotating bodies;
a plurality of temperature detection means arranged at different positions and configured to detect the temperature of the rotating body heated by the heating means;
The temperature difference between the plurality of temperature detection means is compared with the temperature difference between the plurality of temperature detection means in the past, and if the difference between the two exceeds a predetermined value, the temperature difference between the plurality of temperature detection means is determined. a control means for determining that there is an abnormality in the detection result of any of the detection means;
An image forming apparatus comprising: The image forming apparatus according to claim 1, wherein at least one of the plurality of temperature sensing means is a non-contact type temperature sensing means. 3. The image forming apparatus according to claim 1, wherein the plurality of temperature sensing means are arranged at different positions in the axial direction of the rotating body. The control means compares the difference in detected temperature between the plurality of temperature detection means with the difference in temperature detected between the plurality of temperature detection means when the operating state of the fixing section is the same in the past. 3. The image forming apparatus according to 3. The image forming apparatus according to claim 4, wherein the control means compares the temperature difference when paper is not passed. 3. The image forming apparatus according to claim 1, wherein the plurality of temperature sensing means are arranged at the same position in the axial direction of the rotary body but at different positions in the rotational direction of the rotary body. The image forming apparatus according to claim 1, wherein at least one of the rotating bodies is an endless belt. The image forming apparatus according to any one of claims 1 to 7, wherein the control means determines that there is an abnormality when the difference exceeds the predetermined value for a predetermined time or more. 9. The apparatus according to claim 1, further comprising a notification means for notifying a user of an abnormality when it is determined that there is an abnormality in the detection result of any of the plurality of temperature detection means. Image forming device.

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