JP2022084242A - Method for determining abnormality in heater, heating device, fixing device, and image forming apparatus - Google Patents

Abstract

To provide a heating device that can promptly specify a failed heater in a plurality of heaters.SOLUTION: A heating device has: first heaters (H1, H2) that are supplied with power from a first power supply path PwA; second heaters (H3-H5) that are supplied with power from a second power supply path PwB; opening and closing means TR1-TR5 that individually turn on/off the supply of power to the first and second heaters; voltage detection units VD1, VD2 that detect the voltage of the first and second power supply paths; and a control unit 53 that controls on/off actuation of the opening and closing means. The control unit turns off the opening and closing means disposed on one power supply path, causes the opening and closing means disposed on the other power supply path to perform the on/off actuation to temporarily supply power to the first heaters or the second heaters, removes a component of a change of voltage CV2 of the power supply path through which the power is not supplied, the voltage detected by the power detection unit, from a change of voltage CV1 of the power supply path through which the power is temporarily supplied, the voltage detected by the power detection unit, and thereby determines the presence or absence of an abnormality in the heaters to which the power is temporarily supplied.SELECTED DRAWING: Figure 7

Description

The present invention relates to a heater abnormality determination method, a heating device, a fixing device, and an image forming device.

In the conventional electrophotographic image forming apparatus, the toner transferred on the paper is heated and pressed by the fixing device to be fixed on the paper. The fixing device is provided with a heating device provided with a plurality of halogen heaters, planar heaters, and the like for heating the toner.

In a fixing device having such a heating device, if a heater failure or a heater drive circuit failure occurs due to the life or the like, normal heating cannot be performed. However, when the failure remains in some heaters or some heater drive circuits, the insufficient heat quantity of the failed heater is compensated by lighting of other heaters. As a result, there is a problem that the fixing defect is suppressed and the fixing device is continuously used without the failure heater being recognized, and the failure response is delayed.

Therefore, as a failure detection means when a part of a plurality of heaters fails, a plurality of heaters are sequentially switched and turned on in several combinations, and the temperature change due to the switching lighting is detected by a temperature sensor and compared. , There is a technique for identifying a failed heater (Patent Document 1). However, this method does not completely solve the problem of delay in troubleshooting because it takes time to detect the temperature change. (See Patent Document 2). There is also a technique for identifying a failed heater by voltage fluctuation due to switching lighting of the heater (Patent Document 2), but if the power supply voltage fluctuates, there is a possibility of erroneous determination.

The present invention has been made in view of such a situation, and an object of the present invention is to provide a heating device capable of quickly identifying a failed heater among a plurality of heaters regardless of fluctuations in the power supply voltage.

In order to solve the above problems, the heating device of the present invention includes a first heater to which power is supplied from the first power supply path, a second heater to which power is supplied from the second power supply path, and a second heater. An opening / closing means for individually turning ON / OFF the supply of electric power to the first and second heaters, a voltage detecting unit for detecting the voltage of the first and second power supply paths, and ON / OFF of the opening / closing means. It has a control unit that controls the operation, and the control unit turns on the opening / closing means arranged in the other power supply path while the opening / closing means arranged in one power supply path is turned off. By operating / OFF, power is temporarily supplied to the first or second heater, and power is temporarily supplied from the voltage change CV1 detected by the voltage detection unit of the person who has temporarily supplied power. It is characterized in that the component of the voltage change CV2 detected by the voltage detection unit of the side that did not supply the power is removed, and the presence or absence of abnormality of the heater of the side that supplies the power is determined.

According to the heating device of the present invention, the failed heater can be quickly identified regardless of the fluctuation of the power supply voltage.

It is a schematic diagram of the image forming apparatus which concerns on embodiment of this invention. It is a conceptual diagram of the heating device used for the fixing device of an image forming apparatus. It is a schematic diagram of the heating device used in the conventional fixing device. It is a figure which shows the type of operation of the fixing device corresponding to the state of a power source and a heater. It is a flowchart which shows the failure detection process of a fixing device. It is a flowchart which shows the heater failure detection processing of the A side power supply path. It is a flowchart which shows the heater failure detection processing of the B side power supply path. It is a figure which shows an example of the voltage change of the power supply path of A side and B side. It is a conceptual diagram of a heating device, and is (a) the figure when the heaters H1 and H2 are temporarily energized, and (b) the figure when the heaters H3 to H5 are temporarily energized.

(Outline of image forming device)
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic view of an image forming apparatus. The image forming apparatus is not limited to the electrophotographic color printer as shown in FIG. 1, but may be a monochrome printer, a copying machine, a facsimile, or a multifunction device having a plurality of these functions. There may be.

The image forming apparatus shown in FIG. 1 is an apparatus capable of forming a full-color image using four color toners of yellow (Y), magenta (M), cyan (C), and black (K). An intermediate transfer belt 2 serving as an endless belt-shaped image carrier is arranged near the center of the main body of the image forming apparatus (hereinafter referred to as the apparatus main body 1).

The intermediate transfer belt 2 is hung around a plurality of support rollers 28, a drive roller 8, and a secondary transfer facing roller 10. Then, the drive roller 8 is rotationally driven by the drive motor so that the drive roller 8 can be rotationally conveyed clockwise in the figure.

On the intermediate transfer belt 2, a plurality of image forming portions 3Y, 3M, 3C, and 3K corresponding to yellow (Y), magenta (M), cyan (C), and black (K) are formed along the moving direction. A tandem image forming unit 4 arranged side by side is configured. Two exposure devices 5 are arranged on the tandem image forming unit 4.

Further, the image forming portions 3Y, 3M, 3C, and 3K have photoconductor drums 6Y, 6M, 6C, and 6K as latent image carriers that carry toner images of corresponding colors, respectively. At the primary transfer position where the toner image is transferred from the photoconductor drums 6Y, 6M, 6C, 6K to the intermediate transfer belt 2, the intermediate transfer belt 2 is sandwiched between the photoconductor drums 6Y, 6M, 6C, and 6K. The primary transfer rollers 7Y, 7M, 7C, and 7K are provided as components of the primary transfer means.

On the other hand, a secondary transfer unit 9 as a secondary transfer means is arranged below the intermediate transfer belt 2. The secondary transfer unit 9 shown in FIG. 1 transfers the secondary transfer to the secondary transfer nip N1 formed by pressing the secondary transfer roller 11 against the secondary transfer facing roller 10 from the outside of the intermediate transfer belt 2. By applying an electric field with a power source (not shown), the toner image on the intermediate transfer belt 2 is transferred to the recording medium S, which is well known.

An operator panel 27 is provided on the upper part of the apparatus main body 1 for the customer to perform various settings and operations such as print settings. Further, in FIG. 1, a fixing device 12 is arranged next to the secondary transfer unit 9 with a transport belt 15 sandwiched between them.

The fixing device 12 sandwiches the fixing belt 13, which is an endless belt, between the fixing roller 44 and the pressure roller 14 to form a fixing nip. Then, as is well known, the transferred image is fixed on the recording medium S by applying heat and pressure to the recording medium S after image transfer conveyed by the transfer belt 15.

The heat source for heating is five heater lamps 41 arranged in the heating roller 40. The fixing temperature is detected by the temperature detecting means of the thermopile 42 provided in the vicinity of the heating roller 40 and the thermopile 43 provided in the vicinity of the pressure roller 14. Then, the controller board 26 (control unit 53 described later) controls the lighting / extinguishing of the heater lamp 41 so that the fixing is performed at the specified temperature. The controller board 26 is composed of a CPU, a memory for storing a control program for controlling each part of the image forming apparatus, a main storage device, and various interfaces for connecting to the outside of the controller board 26. Will be done.

Here, the image forming operation in the image forming apparatus will be described. When the printing operation is started, image data is sent from the controller board 26 arranged in the controller box 25 provided on the side surface of the apparatus main body 1 to the two exposure devices 5, and image drawing is started from the controller board 26. A signal is emitted. In response to this signal, a drive motor (not shown) rotates and drives the drive roller 8 to drive and rotate the other plurality of support rollers 28, and rotationally conveys the intermediate transfer belt 2.

At the same time, the two exposure devices 5 form monochromatic images of each color on the photoconductor drums 6Y, 6M, 6C, and 6K of the individual image forming portions 3Y, 3M, 3C, and 3K. Then, along with the transfer of the intermediate transfer belt 2, the monochromatic toner images formed on the photoconductor drums 6Y, 6M, 6C, and 6K are sequentially transferred onto the intermediate transfer belt 2 at the primary transfer position and transferred onto the intermediate transfer belt 2. Form a composite color image.

A paper feed table 16 having a plurality of paper feed cassettes 18 serving as a paper feed unit is arranged below the device main body 1. In the paper feed table 16, when the paper feed cassette 18 is selected and the apparatus starts printing, the paper feed roller 17 rotates, and the recording medium S is connected to the transport path R1 from one of the paper feed cassettes 18. Go out to route R.

The unfolded recording medium S is conveyed to the transfer path R1 by the transfer roller 19 provided in the transfer path R. Then, after the recording medium S is abutted against the resist roller 20 and stopped, the resist roller 20 rotates in time with the synthetic color image on the intermediate transfer belt 2 so that the recording medium S is formed by the secondary transfer nip N1. The toner image is transferred to.

The recording medium S after image transfer is fed to the fixing device 12 by the feeding action of the secondary transfer nip N1 and the transport belt 15, and heat and pressure are applied by the fixing belt 13 and the pressurizing roller 14 to apply heat and pressure to the transferred image. (Toner image) is fixed. After this fixing, the recording medium S is conveyed by the discharge roller 21 to a well-known decaler unit 22 that corrects the warp of the recording medium S. Then, the warp of the recording medium S is corrected by the decara roller 23 of the decara unit 22, and the recording medium S is discharged to the outside of the apparatus main body 1 and loaded on the paper ejection tray 24.

(Heating device of fixing device)
Next, the heating device 50 used in the fixing device 12 described above will be described with reference to FIG. 2A. The heating device 50 has a heater unit 51 having five heaters H1 to H5, a heater drive unit 52 for driving the heaters H1 to H5 of the heater unit 51, and a control unit 53 for controlling the heater drive unit 52.

The heater drive unit 52 is connected in parallel to two triacs TR1 and TR2 connected in parallel to the A-side power supply path PwA as the first power supply path and to the B-side power supply path PwB as the second power supply path. It has three triacs TR3 to TR5. These triacs TR1 to TR5 also function as means for opening and closing the power supply path for the heaters H1 to H5, as will be described later.

Two heaters H1 and H2 as first heaters are connected to the two triacs TR1 and TR2, respectively. Further, the thermostats TH1 and TH2 are connected in series to the two heaters H1 and H2, respectively.

Further, the three heaters H3 to H5 as the second heater are connected to the three triacs TR3 to TR5, respectively. Further, the thermostats TH3 to TH5 are connected in series to the three heaters H3 to H5, respectively.

The voltage of the power supply path PwA on the A side is detected by the voltage detection circuit VD1 as the voltage detection unit. Further, the voltage of the power supply path PwB on the B side is detected by the voltage detection circuit VD2 as the voltage detection unit.

Based on the temperature information obtained by the thermopile 42 and 43 during the start-up, standby, and printing operation of the image forming apparatus, the control unit 53 sets the triacs TR1 to TR5 so that the heating roller 40 reaches a predetermined temperature. ON / OFF operation is performed to turn on / off the heaters H1 to H5. The heaters H1 to H5 installed inside the heating roller 40 give priority to cost, and have the same power distribution and output as those generally used for electrophotographic copiers and printers. Use 5 of them.

Printers used for commercial printing are required to support various types of printing paper as a recording medium S. For example, the thickness ranges from about 70 g / m ² to a basis weight of about 70 g / m 2, which is generally used for printers, to a thickness of 400 g / m ² .

In addition to plain paper, it is also necessary to handle special paper with uneven surfaces such as coated paper and rezac paper. Furthermore, printing quality as specified is required even in a low temperature environment or in severe power supply voltage conditions. Therefore, the heaters H1 to H5 of the fixing device 12 are of electric power that can supply the heat taken by the printing paper during printing and the required amount of heat even in the worst conditions including the environment at the time of use.

(Type of system operation of fixing device)
Next, the types of control (system operation) of the fixing device are shown in FIG. This type of control (system operation) is realized by the control unit 53 executing the steps of the flowcharts (FIGS. 4 to 5B) described below.

In FIG. 4, all the triacs TR1 to TR5 are turned off in step S1, and the voltage values of the A side power supply path PwA and the B side power supply path PwB are detected by the voltage detection circuits VD1 and VD2 in step S2, respectively. .. In step S3, it is determined whether or not the voltage value of the power supply path PwA on the A side is normal. When it is determined that the voltage value of the power supply path PwA on the A side is normal, it is determined in step S4 whether or not the voltage value of the power supply path PwB on the B side is normal.

If it is determined that the voltage value of the B-side power supply path PwB is also normal, the heater failure detection process of the power supply A-side path is performed in step S5 (see FIG. 5A). Next, in step S6, the heater failure detection process of the power supply B side path is performed.

Next, in steps S5 and S6, the counts A and B are set to +1 by detecting one heater failure, and it is determined in step S7 whether the count A + the count B = 5. When A + B = 5, all heaters H1 to H5 are determined to be out of order and stop operation.

When A + B ≠ 5, it is determined in step S8 whether A + B = 0. When A + B = 0, all heaters H1 to H5 are normal, so normal operation is performed. When A + B ≠ 0, it is determined that some heaters are out of order and the limiting operation is performed.

Returning to steps S3 and S4, if it is determined that the voltage value of the power supply path PwA on the A side is normal but the voltage value of the power supply path PwB on the B side is not normal, the heater failure detection process of the power supply A side path is performed in step S9. (See FIG. 5A). Next, in step S10, it is determined whether or not the count A = 2. When A = 2, it is determined that the heaters H1 and H2 on the A side are all out of order, and the voltage value of the power supply path PwB on the B side is not normal, so the operation is stopped.

Returning to step S3, if it is determined that the voltage value of the A-side power supply path PwA is not normal, it is similarly determined in step S11 whether or not the voltage value of the B-side power supply path PwB is normal. If it is determined that the voltage value of the power supply path PwB on the B side is not normal, the operation is stopped because the voltage values on both the A side and the B side are not normal.

When it is determined in step S11 that the voltage value of the B-side power supply path PwB is normal, the heater failure detection process of the power supply B-side path is performed in step S12. Here, the count B is set to +1 by detecting one heater failure, and it is determined in step S13 whether the count B = 3.

When B = 3, all the heaters H3 to H5 are determined to be out of order and the operation is stopped. If it is determined that the count B ≠ 3, it is determined that some of the heaters are out of order and the limiting operation is performed.

(Heater failure detection processing of A side route)
Next, the contents of the heater failure detection processing of the two heaters H1 and H2 of the A-side power supply path PwA performed in the above-mentioned steps S5 and S9 will be described with reference to FIG. 5A. First, in step S21, only the triac TR1 is turned on.

The other triacs TR2 to TR5 are left in the OFF state. When the triac TR1 is turned on, the heater H1 is turned on (energized) (step S22).

Next, in step S23, the voltage values V1 and V2 are detected by the voltage detection circuits VD1 and VD2. The voltage value V1 is the voltage value of the power supply path PwA on the A side when the heater H1 is in the ON (energized) state. The voltage value V2 is the voltage value of the B-side power supply path PwB when the heater H1 is in the ON (energized) state.

If the voltage value V2 is a normal value and there is no voltage change when the heater H1 is turned on (energized), the voltage value V1 is a reliable value. In this case, both steps S24 and S28 determine "No" and proceed to step S29.

On the other hand, when it is determined that the voltage value V2 is equal to or higher than the power supply voltage rise threshold value TS1 (TS1 <V2), the power supply abnormality is counted by +1 in step S25. In step S26, it is determined whether or not this count number is equal to or less than the specified number of times. If the number of times is equal to or less than the specified number, the process returns to step S23 and the voltage values V1 and V2 are detected again.

Although the determination is "No" in step S24, if the determination is "Yes" in step S28, the power supply abnormality is counted by +1 in step S25. That is, if the voltage value V2 is the power supply voltage rise threshold TS1 or less (TS1> V2), but the power supply voltage drop threshold TS2 or less (TS2> V2), this is also counted as a power supply abnormality by +1.

If it is determined in step S26 that the count number is equal to or greater than the specified number of times, the power supply abnormality count number is reset to zero in step S27, and then the process returns immediately before step S2 in FIG. Here, the "specified number of times" is set to a predetermined size so that the determination accuracy of steps S24 and S28 is improved in consideration of the variation in the voltage values V1 and V2.

If the voltage value V2 is a normal value, the process proceeds to step S29, and it is determined whether or not the voltage value V1 of the voltage detection circuit VD1 in the state where the heater H1 is turned on is equal to or less than the detection threshold TS3. If V1 <TS3, a normal voltage drop occurs due to the energization of the heater H1, and it is determined that the heater H1 is normal. Therefore, the energization is stopped (OFF) in step S30.

On the contrary, if V1> TS3, a normal voltage drop does not occur even if the heater H1 is energized, and it is determined that the heater H1 is disconnected or the triac TR1 is open failure, and in step S33. After the failure count A is counted by +1 the energization is stopped (OFF). Now that the diagnosis of the heater H1 has been completed, the next steps S31 and S32 proceed to the diagnosis of the heater H2.

The diagnostic method is the same as the diagnosis of the heater H1. After the diagnosis of the heater H2 is completed, the process returns immediately after step S5 or step S9 in FIG.

(B-side path heater failure detection processing)
Next, the contents of the heater failure detection processing of the three heaters H3 to H5 of the B-side power supply path PwB performed in steps S6 and S12 described above will be described with reference to FIG. 5B. First, in step S41, only Triac TR3 is turned ON.

The other four triacs TR1, TR2, TR4, and TR5 are left in the OFF state. When the triac TR3 is turned on, the heater H3 is turned on (energized) (step S42).

Next, in step S43, the voltage values V1 and V2 are detected by the voltage detection circuits VD1 and VD2. The voltage value V1 is the voltage value of the B-side power supply path PwB when the heater H3 is in the ON (energized) state. The voltage value V2 is the voltage value of the power supply path PwA on the A side when the heater H3 is in the ON (energized) state.

If the voltage value V1 is a normal value and there is no voltage change when the heater H3 is turned on (energized), the voltage value V2 is a reliable value. In this case, both steps S44 and S48 determine "No" and proceed to step S49.

On the other hand, when it is determined that the voltage value V1 is equal to or higher than the power supply voltage rise threshold value TS1 (TS1 <V1), the power supply abnormality is counted by +1 in step S45. It is determined in step S46 whether or not this count number is equal to or less than the specified number of times. If the number of times is equal to or less than the specified number, the process returns to step S43 and the voltage values V1 and V2 are detected again.

Although the determination is "No" in step S44, if the determination is "Yes" in step S48, the power supply abnormality is counted by +1 in step S45. That is, if the voltage value V1 is the power supply voltage rise threshold TS1 or less (TS1> V1), but the power supply voltage drop threshold TS2 or less (TS2> V1), this is also counted as a power supply abnormality by +1.

If it is determined in step S46 that the count number is equal to or greater than the specified number of times, the power supply abnormality count number is reset to zero in step S47, and then the process returns immediately before step S2 in FIG. Here, the "specified number of times" is set to a predetermined size so that the determination accuracy of steps S24 and S28 is improved in consideration of the variation in the voltage values V1 and V2.

If the voltage value V1 is a normal value, the process proceeds to step S49, and it is determined whether or not the voltage value V2 of the voltage detection circuit VD2 in the state where the heater H3 is turned on is equal to or less than the detection threshold value TS3. If V2 <TS3, a normal voltage drop occurs due to the energization of the heater H3, and it is determined that the heater H3 is normal. Therefore, the energization is stopped (OFF) in step S50.

On the contrary, if V2> TS3, a normal voltage drop does not occur even when the heater H3 is energized, and it is determined that the heater H3 is disconnected or the triac TR3 is open failure, and the failure occurs in step S53. After the count B is counted by +1 the energization is stopped (OFF).

Now that the diagnosis of the heater H3 is completed, the next steps S51 and S52 proceed to the diagnosis of the heater H4 and the heater H5. The method for diagnosing the heaters H4 and H5 is the same as the diagnosis for the heater H3. After the diagnosis of the heaters H4 and H5 is completed, the process returns immediately after step S6 or step S12 in FIG.

(Example of voltage state in threshold value judgment)
Next, an example of the voltage state in the threshold value determination in steps S24, S28, and S29 of FIG. 5A will be described with reference to FIG. The three horizontal lines in FIG. 6 are the power supply voltage rise threshold value TS1, the power supply voltage drop threshold value TS2, and the heater ON detection threshold value TS3 in order from the top.

In FIG. 6, 1 → 2 → 5 → 6 → 7 → 8 → 9 → 10 → 11'→ 12'→ 13 is the fluctuation of the voltage value V2. During this time, the heater H1 and the heater H2 are turned ON / OFF in order. At this time, the voltage value V1 detected by the voltage detection circuit VD1 is 1 → 2 → 3 → 4 → 5 → 6 → 7 → 8 → 9 → 10 → 11 → 12 → 13 in FIG.

If the voltage value V2 detected by the voltage detection circuit VD2 on the OFF side is TS2 <V2 <TS1, the power supply voltage is normal and there is no voltage fluctuation or the magnitude is negligible. In FIG. 6, the fluctuation of the voltage value V2 is zero from 1 → 2 → 5 → 6. Therefore, the movement of the voltage value V1 at this time (1 → 2 → 3 → 4 → 5 → 6) is a net value that is not affected by the fluctuation of the power supply voltage.

Since the voltage value V1 (3 → 4) when the heater H1 is turned on is lower than the heater ON detection threshold TS3 (V1 <TS3), a normal voltage drop occurs due to the energization of the heater H1 and the heater H1 is normal. It is judged. On the contrary, if the voltage value V1> TS3 in (3 → 4) in FIG. 6, a normal voltage drop does not occur even when the heater H1 is energized, and the heater H1 is disconnected or the triac TR1. It is determined to be an open failure.

The voltage value V2 in FIG. 6 is below the power supply voltage drop threshold TS2 between 6 → 7 → 8 → 9. If the heater H2 is turned ON / OFF during this period, the voltage value V1 detected by the voltage detection circuit VD1 is affected by the voltage drop of the voltage value V2.

That is, even if the voltage value V1 is 6 → 7 → 8 → 9 and falls below the heater ON detection threshold TS3 (V1 <TS3), there is a possibility of disconnection or open failure at V1> TS3, and an erroneous judgment can be made. There is sex. Therefore, in step S28 of FIG. 5A, if there is such a voltage drop, the process does not proceed to step S29 for determining the appropriateness of the voltage value V1, and the power supply abnormality is counted in step S25.

On the contrary, when the voltage value V2 exceeds the power supply voltage rise threshold TS1 between 10 → 11'→ 12'→ 13, when the heater H2 is turned ON / OFF during this period, the voltage detection circuit VD1. The detected voltage value V1 is affected by the voltage rise of the voltage value V2. That is, even if the voltage value V1 exceeds the heater ON detection threshold TS3 at 10 → 11 → 12 → 13 (V1> TS3), there is a possibility that V1 <TS3 is actually normal.

Therefore, although both the heater H2 and the triac TR2 are normal, there is a possibility that a disconnection or an open failure may be erroneously determined. Therefore, in step S24 of FIG. 5A, if there is such a voltage rise, the process does not proceed to step S29 for determining the appropriateness of the voltage value V1, and the power supply abnormality is counted in step S25.

(Conceptual diagram of heating device)
7 (a) and 7 (b) are conceptual diagrams showing a state in which the triacs TR1 (TR2) and TR3 (TR4, TR5) are turned on in FIGS. 5A and 5B so as to be easy to understand. FIG. 7A shows that the triac TR1 (TR2) is turned on and the triacs TR3 to TR5 are turned off (switch SW2 is open). FIG. 7B shows that the Triac TR3 (TR4, TR5) is ON-operated and the Triac TR1 and TR2 are OFF-operation (switch SW1 is open).

In FIG. 7A, when the triacs TR3 to TR5 are turned off, the heaters H3 to H5 are not energized and the load is turned off, so that the voltage of the power supply Pw is detected by the voltage detection circuit VD2 as it is. Therefore, when there is a voltage fluctuation of the power supply Pw, the magnitude of the voltage fluctuation is detected by the voltage detection circuit VD2.

Similarly, when the triacs TR1 and TR2 are turned off in FIG. 7B, the heaters H1 and H2 are not energized and the load is turned off, so that the voltage of the power supply Pw is detected by the voltage detection circuit VD1 as it is. Therefore, when there is a voltage fluctuation of the power supply Pw, the magnitude of the voltage fluctuation is detected by the voltage detection circuit VD1.

The voltage values V1 and V2 detected by the voltage detection circuits VD1 and VD2 are input to the control unit 53, and a predetermined control signal is sent from the control unit 53 to the triacs TR1 to TR5. By this control signal, the triacs TR1 to TR5 are controlled so that the system operation shown in FIG. 3 of the fixing device is performed.

That is, when either one of the power supplies A or B (power supply path PwA, PwB) is normal and the other is abnormal, the limiting operation is performed unless the normal heater is completely out of order. In this limiting operation, for example, the number of sheets to be passed per unit time is limited. Further, if any or both of the A-side heaters H1, H2 and the B-side heaters H3 to H5 are completely out of order, the operation is stopped.

Although the present invention has been specifically described above based on the embodiments, the present invention is not limited to the above-described embodiment and can be variously modified within the scope of the technical idea described in the claims. Needless to say. For example, in the above embodiment, two heaters H1 and H2 are arranged in the power supply path PwA on the A side, and three heaters H3 to H5 are arranged in the power supply path PwB on the B side, but the number of these heaters can be increased or decreased. Is. It is also possible to increase the number of power supply paths to 2 or more. The heaters H1 to H5 are not limited to halogen heaters, and planar heaters and the like are also possible.

1: Device body 2: Intermediate transfer belt
3Y, 3M, 3C, 3K: Image forming part 4: Image forming part 5: Exposure device 6Y, 6M, 6C, 6K: Photoreceptor drum
7Y, 7M, 7C, 7K: Primary transfer roller 8: Drive roller 9: Secondary transfer unit 10: Secondary transfer facing roller 11: Secondary transfer roller 12: Fixing device 13: Fixing belt 14: Pressurized roller 15: Conveying belt 16: Feeding table 17: Feeding roller 18: Feeding cassette 19: Conveying roller 20: Resist roller 21: Discharging roller 22: Decaler unit 23: Declarer roller 24: Paper ejection tray 25: Controller box 26: Controller board 27: Operator panel 28: Support roller 40: Heating roller 41: Heater lamp 42, 43: Thermopile 44: Fixing roller 50: Heating device 51: Heater unit 52: Heater drive unit 53: Control unit H1 to H5: Heater N1: 2 Next transfer nip Pw: Power supply PwA: A side power supply path (first power supply path)
PwB: B side power supply path (second power supply path)
R, R1: Conveyance path S: Recording media TH1 to TH5: Thermostat TR1 to TR5: Triac (opening and closing means)
VD1, VD2: Voltage detection circuit (voltage detection unit)

Japanese Unexamined Patent Publication No. 2016-122147 Japanese Unexamined Patent Publication No. 9-16304

Claims (8)

The first heater to which power is supplied from the first power supply path, and
A second heater to which power is supplied from the second power supply path, and
An opening / closing means for individually turning on / off the supply of electric power to the first and second heaters, and
A voltage detector that detects the voltage of the first and second power supply paths, and
It has a control unit that controls the ON / OFF operation of the opening / closing means.
The first or first operation is performed by the control unit turning on / off the opening / closing means arranged in the other power supply path while the opening / closing means arranged in one power supply path is turned off. While temporarily supplying power to the heater of 2, the voltage detection unit of the person who did not supply power detects from the voltage change CV1 detected by the voltage detection unit of the person who temporarily supplied power. A heating device characterized by removing a component of a voltage change CV2 and determining whether or not there is an abnormality in the heater to which power is temporarily supplied. The first and second heaters have a plurality of heaters connected in parallel to the first and second power supply paths, respectively, and the control unit sequentially turns on / off the opening / closing means. The heating device according to claim 1, wherein electric power is sequentially supplied to the plurality of heaters. The heating device according to claim 2, wherein the control unit sequentially determines whether or not the plurality of heaters are abnormal. The control unit
If it is determined that there is no abnormality in all of the plurality of heaters, the heating device is normally operated.
If it is determined that there is an abnormality only in a part of the plurality of heaters, the heating device is restricted.
If it is determined that all of the plurality of heaters have an abnormality, the heating device is stopped.
The heating device according to claim 3. A fixing device comprising the heating device according to any one of claims 1 to 4. An image forming apparatus comprising the fixing apparatus according to claim 5. A method for determining an abnormality of at least two heaters that are separately connected to at least two power supply paths and supplied with power, and is a heater connected to another power supply path with one power supply path turned off. The voltage change CV1 of the one that temporarily supplied the power was removed from the voltage change CV2 of the one that turned off the power supply path, and the power was temporarily supplied. A method for determining an abnormality in a heater, which comprises determining the presence or absence of an abnormality in one of the heaters. The two heaters have a plurality of heaters connected in parallel to the two power supply paths, and power is supplied to the plurality of heaters in order to determine in order whether or not the plurality of heaters are abnormal. The abnormality determination method according to claim 7, wherein the abnormality determination method is performed.

Images