Image forming apparatus and its control method

Abstract

If a user-replaceable unit is not properly inserted into the main unit, the gears that transmit the driving force from the motor to that unit may not mesh correctly, potentially causing vibrations, vibration-induced banding, and abnormal noises. Therefore, there is a need for a system that can detect incomplete installation of user-replaceable units without incurring additional space or cost. [Solution] An image forming apparatus comprising at least one motor, a motor control unit for rotating the motor, and a drive transmission means for transmitting the driving force of the motor to a load, the apparatus detecting the torque generated by the transmission of the driving force to the load by the drive transmission means and acquiring the amplitude of the detected torque. If the acquired amplitude of the torque exceeds a predetermined value, it is determined that there is an abnormality in the load or the drive transmission means.

Description

Technical Field

[0001] The present invention relates to an image forming apparatus and a control method thereof.

Background Art

[0002] Image forming apparatuses have units that are assumed to be replaced periodically, such as toner cartridges and fixing units. When the toner is consumed or the rollers of the fixing unit are worn and it becomes impossible to form an image normally, replacing them enables normal image formation. Therefore, it is common for image forming apparatuses to adopt a configuration that allows users to easily replace these units. Patent Document 1 describes a technique for preventing problems when a replaceable fixing unit is not properly installed by a user. According to this, a technique for checking whether a replacement unit is properly installed is described using existing means for detecting the coupling state between the fixing unit and the apparatus main body, means for detecting a recording medium sandwiched between the pressure rotating body and the heating rotating body of the fixing unit, etc.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] As described in Patent Document 1, in a replaceable unit, space and cost are required to install a sensor that confirms whether the user-replaceable unit is properly installed. If the user-replaceable unit is not properly installed on the main unit, the gears that transmit driving force to that unit may not mesh properly, potentially causing vibration, vibration-induced banding, or abnormal noise. Therefore, there is a need to detect whether the replaceable unit is properly installed without incurring additional space or cost, and to notify the user or service technician if the installation is incorrect.

[0005] The object of the present invention is to solve at least one of the problems of the prior art described above.

[0006] The objective of the present invention is to provide a technology that can detect whether a motor load, such as a replaceable unit, is properly installed, without incurring additional space or cost. [Means for solving the problem]

[0007] To achieve the above objective, an image forming apparatus according to one aspect of the present invention has the following configuration. That is, At least one motor and A motor control unit that rotates the motor, A drive transmission means for transmitting the driving force of the motor to the load, A detection means for detecting torque generated when the driving force is transmitted to the load by the drive transmission means, An acquisition means for acquiring the amplitude of the torque detected by the detection means, The device is characterized by having a determination means that determines that there is an abnormality in the load or the drive transmission means when the amplitude of the torque acquired by the acquisition means exceeds a predetermined threshold. [Effects of the Invention]

[0008] According to the present invention, it is possible to detect whether a motor load, such as a replaceable unit, is properly installed without incurring additional space or cost.

[0009] Other features and advantages of the present invention will become apparent from the following description with reference to the accompanying drawings. In the accompanying drawings, the same or similar components are given the same reference numeral. [Brief explanation of the drawing]

[0010] The attached drawings are included in the specification and constitute part thereof, illustrating embodiments of the present invention and are used together with the description to explain the principles of the present invention. [Figure 1] A schematic diagram of a tandem-type color image forming apparatus using an electrophotographic process according to an embodiment of the present invention. [Figure 2] A diagram illustrating the motor control unit according to Embodiment 1. [Figure 3] A diagram showing the configuration of motor A according to Embodiment 1. [Figure 4] Block diagram (A) illustrating the motor control algorithm according to Embodiment 1 of the present invention, and block diagram (B) illustrating the speed control algorithm based on speed estimation values ​​among the motor control algorithms performed by the microcontroller according to Embodiment 1. [Figure 5] A diagram illustrating the relationship of the rotor position of a motor according to Embodiment 1 of the present invention. [Figure 6] A diagram illustrating the drive configuration of motor A according to Embodiment 1. [Figure 7] A diagram illustrating the current value of motor A when motor A according to Embodiment 1 is rotated. [Figure 8] A diagram illustrating a method for calculating the current ripple value of motor A according to Embodiment 1. [Figure 9] This figure shows an example of the average current ripple value in Embodiment 1, when the driving force of motor A is normally transmitted to the photoreceptor and when the photoreceptor is not fully installed. [Figure 10]A flowchart for explaining the processing by the color image forming apparatus according to Embodiment 1 of the present invention. [Figure 11] A block diagram for explaining the motor control algorithm according to Embodiment 2 of the present invention. [Figure 12] A diagram showing an example of the relationship between the meshing frequency of the gears of the drive train for each unit driven by the A motor and the one-round frequency. [Figure 13] A flowchart for explaining the processing by the color image forming apparatus according to Embodiment 2.

Mode for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the invention according to the claims. Although a plurality of features are described in the embodiments, not all of these plurality of features are essential for the invention, and the plurality of features may be arbitrarily combined. Further, in the accompanying drawings, the same or similar configurations are denoted by the same reference numerals, and redundant descriptions are omitted.

[0012] [Embodiment 1] FIG. 1 is a schematic configuration diagram of a tandem type color image forming apparatus using an electrophotographic process according to an embodiment of the present invention. Referring to this figure, the image forming operation of the configuration of the image forming apparatus according to the embodiment will be described.

[0013] The tandem color image forming apparatus is configured to be able to form a full-color image by overlapping four colors of toner: yellow (Y), magenta (M), cyan (C), and black (K). And for image formation of each color, a laser scanner (11Y, 11M, 11C, 11K) and a cartridge (12Y, 12M, 12C, 12K) are provided. Hereinafter, Y, M, C, and K given to the reference numerals represent parts corresponding to yellow, magenta, cyan, and black, respectively. Each cartridge includes a photoreceptor (13Y, 13M, 13C, 13K) that rotates in the direction of the arrow in the figure, a photoreceptor cleaner (14Y, 14M, 14C, 14K) provided so as to contact the photoreceptor, a charging roller (15Y, 15M, 15C, 15K), and a developing device having a developing roller (16Y, 16M, 16C, 16K). Further, an intermediate transfer belt 19 is provided in contact with the photoreceptors of each color, and primary transfer rollers (18Y, 18M, 18C, 18K) are installed so as to sandwich the intermediate transfer belt 19 and face each other. The photoreceptors (13Y, 13M, 13C) and the fixing device 30 are rotationally driven by an A motor 101 (Fig. 2), and the intermediate transfer belt 19 and the photoreceptor 13K are rotationally driven by a B motor (not shown). Also, the developing rollers (16Y, 16M, 16C, 16K) are rotationally driven by a C motor (not shown). These A motor 101, B motor, and C motor are all DC brushless motors, and which motor rotationally drives each roller is not limited to the embodiment.

[0014] A paper feed roller 25, separation rollers 26a and 26b, and a registration roller 27 are provided downstream of the conveyance of the cassette 22 that stores the paper urchased, and a conveyance sensor 28 is provided near the downstream side in the paper conveyance direction of the registration roller 27. Further, a secondary transfer roller 29 that contacts the intermediate transfer belt 19 and a fixing device 30 are disposed downstream of the conveyance sensor 28 in the conveyance path.

[0015] The controller (printer control unit) 31 is the control unit for the color image forming apparatus and includes a CPU (central processing unit) 32 equipped with ROM 32a, RAM 32b, timer 32c, etc., and various input / output control circuits (not shown). The display panel 33 displays the screen based on signals from the CPU 32.

[0016] Next, the electrophotographic process will be briefly explained. In the dark inside the cartridge (12Y, 12M, 12C, 12K), the surface of the photoreceptor (13Y, 13M, 13C, 13K) is uniformly charged by the charging roller (15Y, 15M, 15C, 15K). The photoreceptor (13Y, 13M, 13C) is configured to rotate when the driving force of motor A 101 is transmitted by gears. Similarly, the photoreceptor 13K and the intermediate transfer belt 19 are configured to rotate when the driving force of motor B is transmitted by gears. Next, a laser scanner (11Y~11K) irradiates the surface of the photoreceptor (13Y~13K) with laser light modulated according to the image data. The charged area irradiated by the laser light is removed, forming an electrostatic latent image on the surface of the photoreceptor (13Y~13K). In the developing unit, toner is deposited onto the electrostatic latent image on the photoreceptor (13Y~13K) by a developing bias from a developing roller (16Y~16K) that holds a certain amount of toner layer, thereby forming toner images of each color on the surface of the photoreceptor (13Y~13K).

[0017] The toner image formed on the surface of the photoreceptor (13Y~13K) is attracted to the intermediate transfer belt 19 by a primary transfer bias applied to the primary transfer roller (18Y~18K) at the nip portion between the photoreceptor and the intermediate transfer belt 19.

[0018] Furthermore, the CPU 32 controls the image formation timing for each cartridge (12Y~12K) according to the belt transport speed, and sequentially transfers each toner image onto the intermediate transfer belt 19. In this way, a full-color image is finally formed on the intermediate transfer belt 19. Meanwhile, the paper 21 in the cassette 22 is transported by the paper feed roller 25, and the separation rollers 26a and 26b ensure that only one sheet of paper 21 passes through the register roller 27 and is transported to the secondary transfer roller 29. After that, at the nip between the secondary transfer roller 29 downstream of the register roller 27 and the intermediate transfer belt 19, the toner image on the intermediate transfer belt 19 is transferred to the paper 21. Finally, the toner image on the paper 21 is heat-fixed by the fuser 30, which rotates due to the driving force of the A motor 101 transmitted by gears. The paper with the image fixed in this way is then discharged from the image forming apparatus.

[0019] The color image forming apparatus is equipped with an ambient temperature sensor 40 that measures the ambient temperature of the outside air, and it is possible to set the image forming parameters according to the measured ambient temperature. The sensor group 41 also includes sensors that detect the opening and closing of the cartridge door, which is opened and closed to replace the cartridge, and the opening and closing of the fuser door, which is opened and closed to insert the fuser.

[0020] Next, we will describe the configuration for rotating motor A 101.

[0021] Figure 2 is a diagram illustrating the motor control unit 110 according to an embodiment.

[0022] The motor control unit 110 drives the A motor 101 without sensors. The motor control unit 110 is equipped with a arithmetic processing means using a microcontroller 201. The microcontroller 201 incorporates a communication port 202, an AD converter 203, a counter 204, a non-volatile memory 205, a reference clock generation unit 206, a memory 207, a PWM port 208, and a current value calculation unit 209, and operates when VC1=3.3V is supplied from a low-voltage power supply. The counter 204 performs counting operations based on the reference clock generated by the reference clock generation unit 206, and based on the count value, measures the period of the input pulse and generates a PWM signal. The PWM port 208 has six terminals and outputs PWM signals of three high-level signals (UH, VH, WH) and three low-level signals (UL, VL, WL).

[0023] The motor control unit 110 also includes a three-phase inverter 211 as a voltage application means, which has three switching elements on the high-level side (M1, M3, M5) and three on the low-level side (M2, M4, M6). Transistors or FETs can be used as switching elements. Each switching element is connected to a PWM port 208 via a gate driver 210, and can be controlled ON / OFF by a PWM signal. The gate driver 210 and each switching element are connected as follows: G1, G2..., G6 of the gate driver 210 are connected to G1 of switching element M1, G2,... of switching element M2, and G6 of switching element M6, respectively. Each switching element is configured to turn ON when the PWM signal is high level and OFF when it is low level.

[0024] The U, V, and W phase outputs 217 of the inverter 211 are connected to the coils 213, 214, and 215 of the A motor 101, allowing control of the coil current of each coil 213, 214, and 215. The coil current of each coil 213, 214, and 215 is converted into a voltage by a current detection unit 216 equipped with current detection resistors 219, 220, and 221. This voltage is amplified by an amplifier 218, and an offset voltage is applied before it is input to the AD converter 203 of the microcontroller 201. The voltage values ​​detected by the current detection unit 216 are denoted as Uin, Vin, and Win. However, the voltage value obtained from resistor 219 is denoted as Uin, the voltage value obtained from resistor 220 as Vin, and the voltage value obtained from resistor 221 as Win. The voltage values ​​amplified by amplifier 218 are denoted as Uout, Vout, and Wout. The current value calculation unit 209 treats the case where current flows from the inverter 211 to the A motor 101 as positive, and performs a predetermined calculation on the A / D converted data (hereinafter referred to as AD value) to calculate the current value flowing through each resistor. Next, the structure of the A motor 101 will be described.

[0025] Figure 3 shows the configuration of motor A 101 according to this embodiment.

[0026] Motor A 101 has a 6-slot stator 501 and a 4-pole rotor 502. The stator 501 is equipped with U-phase, V-phase, and W-phase coils 213, 214, and 215, respectively. The rotor 502 is made of permanent magnets and has two sets of N / S poles. For simplicity, the number of poles of the rotor 502 is assumed to be 4. Since the number of poles is 4, the position obtained by rotating the rotor 502 counterclockwise by π / 2 [rad] in mechanical angle from the position facing the coils 213 corresponds to an electrical angle of π [rad]. For convenience, the rotation direction is considered positive when it is counterclockwise. In sensorless vector control, the current value flowing in the direction facing the rotor 502 is denoted as Id, and the current value flowing in the direction rotated counterclockwise by π / 2 [rad] in electrical angle from that point is denoted as Id. Id is a current value that does not contribute to rotational torque, and Iq is a current that contributes to rotational torque. Id_ref is the current command value for current value Id, and Iq_ref is the current command value for current value Iq.

[0027] Figure 4(A) is a block diagram illustrating a motor control algorithm according to an embodiment of the present invention. Referring to this figure, the motor control algorithm performed by the microcontroller 201 will be explained, using the case where the rotor position is estimated from the induced voltage of the motor and the motor speed is controlled as an example.

[0028] This algorithm can be divided into three parts: rotor stop position estimation, forced commutation, and speed control based on speed estimates. First, let's explain rotor stop position estimation.

[0029] The rotor's stopping position is estimated by the electrical angle calculation unit 301 at the time of stopping. One method for detecting the rotor's stopping position utilizes the phenomenon that the inductance of each coil, U, V, and W, changes depending on the rotor's stopping position. Specifically, a predetermined voltage is applied to the combination of coils UV, UW, VW, VU, WU, and WV, and the magnitude of the inductance of each coil is determined by the magnitude of the coil current that flows at that time. The rotor's stopping position is then detected based on the results. (See, for example, Japanese Patent Publication No. 2015-104263) The three-phase AC phase when energizing each coil 213, 214, and 215 is set to an electrical angle of 0 [rad] so that Id = 0 [A] when the south pole of the rotor 502 is facing the coil 213. When the electrical angle calculation unit 301 determines that the rotor 502 is facing the coil 213, it outputs a reference electrical angle θ_std = 0 [rad].

[0030] Next, we will explain the forced commutation control algorithm using the case where the reference electrical angle θ_std = 0 [rad] as an example.

[0031] When the motor starts up, no induced voltage is generated, so speed feedback control is not performed, and the motor is driven by forced commutation. The current control unit 302 performs current feedback control based on Id_ref and Iq_ref, which correspond to the current command values ​​stored in advance in the non-volatile memory 205, and the current values ​​Id and Iq, which correspond to the output torque of motor A 101. It then outputs voltage command values ​​Vd_ref and Vq_ref. Id_ref, Iq_ref, Id, Iq, Vd_ref, and Vq_ref represent the current command value, current, and voltage command value in the rotor coordinate system, respectively.

[0032] The coordinate transformation unit performs conversion from the rotor coordinate system (d, q) to the stator coordinate system (U, V, W), or from the stator coordinate system (U, V, W) to the rotor coordinate system (d, q). Meanwhile, the angle calculation unit 303 calculates the rotor position θ_ref by integrating the speed command value ω_ref input from the controller 31 to the initial electrical angle θ_ini at predetermined intervals. The voltage command values ​​Vd_ref and Vq_ref are converted into voltage command values ​​Vu, Vv, and Vw, which are actually applied to the U-phase coil, V-phase coil, and W-phase coil, respectively, by the coordinate transformation unit based on the rotor position θ_ref, and output. In this embodiment, the initial electrical angle θ_ini refers to the electrical angle corresponding to the initial excitation phase at motor startup. The initial electrical angle θ_ini is set to a value obtained by adding the offset defined in the offset setting 304 to the reference electrical angle θ_std, which corresponds to the rotor's stopping position. The above is a description of the forced commutation control algorithm.

[0033] Figure 4(B) is a block diagram illustrating the speed control algorithm based on speed estimation, which is part of the motor control algorithm performed by the microcontroller 201.

[0034] The microcontroller 201 acquires current information Uout, Vout, and Wout, corresponding to the motor coil currents Iu, Iv, and Iw obtained from the amplifier 218, at a motor rotation speed at which sufficient induced voltage is generated. Then, the angular velocity / angle estimation unit 801 estimates the rotor position θ_est and the velocity ω_est from the current information Uout, Vout, and Wout and the command voltages Vu, Vv, and Vw. Then, the speed control unit 802 calculates a current command value Iq_ref to make the estimated velocity ω_est follow the speed command value ω_ref, using the velocity command value ω_ref transmitted from the controller 31 and the previously calculated velocity estimate value ω_est. The current control unit 302 calculates voltage command values ​​Vd_ref and Vq_ref in the rotor coordinate system from the current command value Iq_ref, Id_ref, which corresponds to the current command value previously stored in the non-volatile memory 205, and Id and Iq, which correspond to the load current applied to the A motor 101. Finally, using the estimated rotor position θ_est and the voltage command values ​​Vd_ref and Vq_ref in the rotor coordinate system, the coordinate transformation unit determines the voltage command values ​​Vu, Vv, and Vw to be actually applied to the U-phase coil, V-phase coil, and W-phase coil. This concludes the explanation of speed control based on speed estimation values.

[0035] Figure 5 is a diagram illustrating the relationship of the rotor positions of a motor according to an embodiment of the present invention.

[0036] With the rotor 502 stopped at a position corresponding to the reference electrical angle θ_std = 0 [rad], the offset θ_off = 0. Figures 5(A) to (C) show the behavior of the rotor 502 when the excitation layer is switched to electrical angles of 0 [rad], π / 3 [rad], and π [rad].

[0037] In Figure 5, the long arrow represents a vector of current value Iq, which is controlled according to the current command value Iq_ref. The short arrow represents a vector of current value Id, which is controlled according to the current command value Id_ref. The motor is controlled by the combined vector current of Iq and Id. During forced commutation control, both Iq_ref and Id_ref operate at predetermined values. During sensorless control, Id_ref operates at a predetermined value, and Iq_ref operates at a value output from the speed control 802.

[0038] Figure 6 is a diagram illustrating the drive configuration of the A motor 101 according to the embodiment. The loads driven by the A motor 101 are the photoreceptors (13Y, 13M, 13C) and the fuser 30. However, for the sake of simplicity, the drive configuration for the photoreceptor 13Y will be described below. The drive configurations for the photoreceptors (13M, 13C) and the fuser 30 are the same as the drive configuration for the photoreceptor 13Y, which will be described later, so their explanation will be omitted below.

[0039] Figures 6(A) and 6(B) illustrate the drive configuration in which motor A 101 rotates the photoreceptor 13Y, and the state during rotational drive. When motor A 101 rotates, the driving force from motor A 101 is transmitted to the photoreceptor interface gear 130Y by a drive transmission means A consisting of a gear train. Subsequently, the photoreceptor interface gear 130Y, which is the main body side of the color image forming apparatus according to this embodiment, and the photoreceptor gear 131Y, which is the photoreceptor side and is a user-replaceable unit, are driven at the interface section. The driving force transmitted to the photoreceptor gear 131Y at the interface section is transmitted to the photoreceptor 13Y, which is located coaxially. Now, focusing on the interface section in Figures 6(A) and 6(B), it can be seen that the distance between the photoreceptor interface gear 130Y and the photoreceptor gear 131Y is different in Figures 6(A) and 6(B). In Figure 6(A), the distance between the photoreceptor interface gear 130Y and the photoreceptor gear 131Y is maintained at an appropriate distance, whereas in Figure 6(B), the distance between the photoreceptor interface gear 130Y and the photoreceptor gear 131Y is too large. In Figure 6(B), it is thought that the user-replaceable unit is not installed in the correct position. In the case of Figure 6(B), the distance between the interface gear 130Y and the photoreceptor gear 131Y is too large. Therefore, if the A motor 101 is rotated in this state, the driving force transmission at the interface becomes unstable, which may cause banding, vibration, gear wear due to tooth skipping, and abnormal noise.

[0040] Next, with reference to Figure 7, the current value of motor A 101 when the motor A 101 according to this embodiment is rotated will be explained.

[0041] Figure 7 illustrates the current value of motor A 101 when it is rotated according to this embodiment. In Figure 7, the horizontal axis represents time, and the vertical axis represents the current value flowing through motor A 101.

[0042] Since the current value of motor A 101 is adjusted to achieve a predetermined speed, there is a certain correlation between the current value of motor A 101 and the torque value applied to the motor shaft of motor A 101. In particular, when vector control is used so that Id, which is a current that does not contribute to torque, becomes 0, the correlation between the current value of motor A 101 and the torque value applied to the motor shaft of motor A 101 becomes even stronger.

[0043] Figure 7(A) shows the current value trend of motor A 101 when the distance relationship between the photoreceptor interface gear 130Y and the photoreceptor gear 131Y is normal, as shown in Figure 6(A). In Figure 7(A), it can be seen that the ripple in the current value when motor A 101 is rotated remains small.

[0044] On the other hand, Figure 7(B) shows the current value change of motor A 101 when the distance between the interface gear 130Y and the photoreceptor gear 131Y is too large, as in Figure 6(B), resulting in unstable drive transmission at the interface. When motor A 101 is rotated, the current value shows that periodic ripple is occurring, indicating that periodic torque fluctuations are occurring on the motor shaft of motor A 101. As shown in Figure 7(B), periodic ripple is occurring in the current value of motor A 101. The period T0 depends on the malfunction of the gear train within motor A 101, but in the case of the state shown in Figure 6(B), it is often the period of one tooth or one rotation of the photoreceptor interface gear 130Y or photoreceptor gear 131Y. As shown in Figure 6(B), if some malfunction occurs in the gear train, causing unstable drive transmission and resulting in banding, vibration, tooth skipping, or abnormal noise, torque fluctuations occur at the period of one tooth or one rotation of the related gears. Therefore, as shown in Figure 7(B). Ripple occurs in the current value of motor A 101. Therefore, by detecting the ripple in the current value of motor A 101, it is possible to detect a malfunction in the gear train that rotates motor A 101.

[0045] Figure 8 illustrates a method for calculating the current ripple value of motor A 101 according to an embodiment. Figure 8 shows the current values ​​of motor A 101 when the driving force of motor A 101 is normally transmitted to the photoreceptor 13Y and when the photoreceptor 13Y is incompletely mounted. In Figure 8, the horizontal axis represents time, and the vertical axis represents the current value Iq flowing through motor A 101.

[0046] When the driving force of motor A 101 is properly transmitted to the photoreceptor 13Y, the current value Iq of motor A 101 fluctuates between levels Ia and Ib, as shown in the upper graph of Figure 8. Then, at a predetermined timing, the current value increases by Io due to load fluctuations, and thereafter the current value Iq of motor A 101 fluctuates between levels Ia+Io and Ib+Io.

[0047] The method for calculating the current ripple value according to the embodiment will be explained with reference to the graph of the normal state.

[0048] At a predetermined sampling period, the current value Iq of motor A 101 is acquired, and the maximum value Iq_max and minimum value Iq_min within the predetermined period T are calculated. From the calculated maximum value Iq_max and minimum value Iq_min, the current ripple value Iq_lip is calculated. In the normal case shown in Figure 8, the method for calculating the current ripple value Iq_lip is explained using sections A, B, and C as examples. In section A, Iq_max is Ia, Iq_min is Ib, and Iq_lip is Ia-Ib. In section B, where a load fluctuation of Io occurs, Iq_max is Ia+Io, Iq_min is Ib, and Iq_lip is Ia-Ib+Io. In section C, after the load fluctuation, Iq_max is Ia+Io, Iq_min is Ib+Io, and Iq_lip is Ia-Ib. In this calculation method, the average current ripple value Iq_lip_ave is calculated by averaging the Iq_lip calculated in each section over a predetermined period during which motor A 101 is rotating. The average current ripple value Iq_lip_ave for the seven sections in Figure 8 is 6(Ia-Ib)+Ia-Ib+Io) / 7=(Ia-Ib)+Io / 7. By increasing the number of sections for which this average value is calculated, the influence of Io, which is the current due to load fluctuations in section C, can be reduced.

[0049] Next, we will explain the change in the ripple current value of motor A 101 when it is not fully installed.

[0050] When the drive transmission is unstable, such as in the case of incomplete installation, the current value Iq of motor A 101 not only fluctuates between the levels of Ia and Ib, but also changes while increasing by Ilp and decreasing by Ilm at predetermined intervals, as shown in the lower graph of Figure 8. At predetermined timings, the current value increases by Io due to load fluctuations, and thereafter the current value Iq of motor A 101 not only fluctuates between the levels of Ia+Io and Ib+Io, but also changes while increasing by Ilp and decreasing by Ilm at predetermined intervals. In the case of incomplete installation shown in Figure 8, the method for calculating the current ripple value Iq_lip will be explained using sections A, B, and C as examples. In section A, Iq_max is Ia+Ilp, Iq_min is Ib-Ilm, and Iq_lip is Ia-Ib+Ilp+Ilm. In section B, where load fluctuations in Io occur, Iq_max becomes Ia + Ilp + Io, Iq_min becomes Ib - Ilm, and Iq_lip becomes Ia - Ib + Ilp + Ilm. In section C, after the load fluctuation, Iq_max becomes Ia + Ilp + Io, Iq_min becomes Ib - Ilm + Io, and Iq_lip becomes Ia - Ib + Ilp + Ilm. In this calculation method, the average current ripple value Iq_lip_ave is calculated by averaging the Iq_lip calculated in each section over a predetermined period during which motor A is rotating. The average current ripple value Iq_lip_ave for the 7 sections in the case of incomplete installation shown in Figure 8 is Ia - Ib + Ilp + Ilm + Io / 7. By increasing the number of sections for calculating this average value, the influence of Io, which is the current due to load fluctuations in section C, can be reduced.

[0051] Figure 9 shows an example of the average current ripple value in the embodiment, when the driving force of motor A 101 is normally transmitted to the photoreceptor 13Y and when the photoreceptor 13Y is in an incompletely mounted state. In Figure 9, the case where the number of intervals for calculating the average value is 1000 is shown.

[0052] As shown in Figure 9, a significant difference can be observed in the average current ripple value Iq_lip_ave between improper installation and normal installation. Therefore, by calculating the average current ripple value Iq_lip_ave of motor A 101, if the average current ripple value Iq_lip_ave of motor A 101 is greater than a predetermined value, it can be determined that some kind of malfunction has occurred in the gear train of the drive train of motor A 101. In particular, if the average current ripple value Iq_lip_ave is greater than a predetermined value immediately after replacing the cartridge, it can be determined that there is a malfunction due to the cartridge not being properly installed, or a sign of an impending malfunction, and the user can be notified to reinsert the cartridge.

[0053] In the embodiment, an example was described in which a malfunction in the drive train of motor A 101 up to the photoreceptor gear connected to motor A 101 is detected using the current value Iq of motor A 101 and the average current ripple value Iq_lip_ave. However, the present invention can also be applied to cases where, for example, the load connected to the motor is a fuser, and a malfunction in the drive train up to the fuser or incomplete insertion of the fuser is detected and notified to the user. Therefore, the motor configuration and the load connected to the motor are not limited to the embodiment. Also in the embodiment, the average current ripple value Iq_lip_ave was calculated by calculating the ripple value from the maximum and minimum current values ​​over a predetermined period, and then summing these ripple values ​​and averaging them. However, the present invention is not limited to the method of calculating the ripple value in the embodiment.

[0054] Figure 10 is a flowchart illustrating the process performed by a color image forming apparatus according to Embodiment 1 of the present invention. The process shown in this flowchart is achieved when the CPU 32 of the controller 31 executes a program stored in the ROM 32a.

[0055] When this process begins, CPU32 performs the initial setup of each value in RAM32b (n=0, k=0, Iq_lip_int=0) in S101. Here, the variable n is used to count the number of times the current value Iq flowing through motor A 101 is acquired. The variable k is used to count the number of times the accumulated current ripple value has been accumulated in order to find the average of the accumulated current ripple value. Iq_lip_int is a variable used to accumulate Iq_lip in S108, which will be described later. Next, proceeding to S102, CPU32 starts up motor A 101. Then, in S103, CPU32 waits for the rotation speed of motor A 101 to reach the target speed and proceeds to S104. In S104, CPU32 acquires the current value of motor A 101. This is obtained by calculating the current value flowing through resistors 219, 220, and 221 based on the voltage value (digital value) input from AD converter 203, as explained with reference to Figure 2. Then, the current value Iq obtained here is assigned to Iq_n in RAM32b. Then, the process proceeds to S105, where CPU32 checks if the value of variable n has become 9. If it is not 9, the process proceeds to S106, increments the value of variable n by 1, and proceeds to S104. In S105, if the value of variable n becomes 9, the process proceeds to S107. As a result, 10 current values ​​Iq_0 to Iq_9 have been obtained.

[0056] In S107, the CPU32 calculates the maximum value Iq_max and minimum value Iq_min of the current values ​​Iq_0 to Iq_9 obtained multiple times. Next, in S108, the CPU32 calculates the current value ripple value Iq_lip from the difference between Iq_max and Iq_min calculated in S107. Here, the current value ripple value Iq_lip is obtained by subtracting Iq_min from Iq_max. Then, in S109, the CPU32 multiplies the Iq_lip calculated in S108. Specifically, it calculates Iq_lip_int = Iq_lip_int + Iq_lip. Then, in S110, the CPU32 increments the variable k by 1 and proceeds to S111 to determine if there is a stop command to stop the motor rotation. If there is no motor stop command, it proceeds to S112, resets the variable n to 0, and proceeds to S104 to execute the same process as described above. When the motor rotation stop command is input in S111, the process proceeds to S113. In S113, the cumulative value of the current ripple value Iq_lip for the number of times the value indicated by variable k is stored in Iq_lip_int.

[0057] In S113, the CPU 32 calculates the average ripple current Iq_lip_ave based on the current ripple value Iq_lip_int and the variable k accumulated in S109. Specifically, it calculates the average ripple current Iq_lip_ave = Iq_lip_int / k. Next, in S114, the CPU 32 determines whether the average ripple current Iq_lip_ave calculated in S113 is greater than or equal to a predetermined value. If it determines that it is greater than or equal to the predetermined value, it proceeds to S115, where it determines that there is some kind of malfunction (abnormality) in the drive train of motor A 101 and proceeds to S117. On the other hand, if the CPU 32 determines in S114 that the average ripple current Iq_lip_ave is less than the predetermined value, it determines that it is normal and proceeds to S116, where it determines that there is no malfunction in the drive train of motor A 101 and terminates this process.

[0058] In S117, the CPU 32 determines whether there is any recent history of opening or closing the cartridge door, as detected by the cartridge sensor of the sensor group 41. If it determines that such history exists, it proceeds to S118. In S118, the CPU 32 determines that the cartridge has not been inserted completely due to removal or reinstallation, and displays a message on the display panel 33 or the like prompting the user to reinsert the cartridge, and then terminates this process. On the other hand, if the CPU 32 determines in S117 that there is no recent history of opening or closing the cartridge door for inserting a cartridge due to user operation, it proceeds to S119. In S119, the CPU 32 determines whether there is any recent history of opening or closing the fuser door, as detected by the fuser sensor of the sensor group 41. If it determines that such history exists, it determines that the fuser has not been inserted completely due to removal or reinstallation, and proceeds to S120, where it displays a message on the display panel 33 or the like prompting the user to reinsert the fuser, and then terminates this process. Furthermore, if the CPU 32 determines in S119 that there is no history of opening or closing the fuser door for inserting the fuser due to recent user operations, the process proceeds to S121. In S121, the CPU 32 notifies the user or service technician via the display panel 33 or the like that there is a possibility of a malfunction in the drive train of motor A 101, and then terminates this process.

[0059] In Embodiment 1, units that may be improperly installed, such as cartridges and fusers, were identified based on the most recent opening and closing of the cartridge door or fuser door. However, for example, replacement history could be obtained using information such as non-volatile memory located inside the cartridge or fuser, and units that may be improperly installed could be identified based on that replacement history.

[0060] As described above, Embodiment 1 allows for the detection of improperly installed user-replaceable units and malfunctions in the drive train from the motor without incurring additional space or cost. Furthermore, by notifying the user or service technician of the detection results, it is possible to encourage the user to reinstall the replaceable units or for service technicians to inspect the drive train.

[0061] [Embodiment 2] Next, Embodiment 2 of the present invention will be described with reference to Figures 11 to 13. However, Embodiment 2 is merely illustrative, and the present invention is not limited to these configurations. Furthermore, the configuration of the color image forming apparatus according to Embodiment 2 is the same as that of Embodiment 1 described above, so its description will be omitted.

[0062] In Embodiment 1 described above, an example was explained in which a malfunction in the drive train of motor A 101 or an improper installation of a user-removable unit was detected from the ripple value of the current flowing through motor A 101. In contrast, Embodiment 2 describes an example in which a malfunction occurred in which unit by frequency analysis of the current value flowing through motor A 101.

[0063] Figure 11 is a block diagram illustrating the motor control algorithm according to Embodiment 2 of the present invention. Figure 11 is a block diagram of the motor control algorithm performed by the microcontroller 201, in which the frequency analysis block used in Embodiment 2 has been added to the block diagram relating to speed control based on speed estimation values.

[0064] When controlling the speed of the motor, the current Iq, which contributes to the torque, is output after coordinate transformation. The output Iq is input to the Iq frequency analysis unit 803, and by performing frequency analysis in the Iq frequency control unit 803, it is possible to obtain something equivalent to the torque fluctuation amount for each frequency. Based on the torque fluctuation amount information for each frequency, it becomes possible to detect which unit has a malfunction in the gear train, causing unstable drive transmission, banding, vibration, tooth skipping, or abnormal noise. As in Embodiment 1, the microcontroller 201 and the Iq frequency analysis unit 803 are located within the motor control unit 110, and the motor control unit 110, microcontroller 201, and Iq frequency analysis unit 803 operate based on instructions from the CPU 32, which is the printer control unit 31. The speed information of motor A 101, Iq value, and Iq frequency analysis results calculated by the microcontroller 201 are transmitted from the microcontroller 201 to the CPU 32.

[0065] Figure 12 shows an example of the relationship between the gear meshing frequency and the rotational frequency of the drive train for each unit driven by motor A 101.

[0066] When a malfunction occurs in the gear train that transmits driving force to a unit, resulting in unstable drive transmission, the torque fluctuations at the meshing frequency and the rotation frequency increase. The meshing frequency and rotation frequency differ depending on the number of teeth and reduction ratio of each gear, such as the fuser gear, fuser interface gear, photoreceptor gear, photoreceptor interface gear, and the pinion gear of the A motor 101. In other words, if a frequency is detected where the torque fluctuation amount is greater than a predetermined value, it indicates that a malfunction has occurred in the gear train corresponding to the unit corresponding to that frequency. For example, if a malfunction such as abnormal noise occurs at the meshing frequency or rotation frequency, it is likely that the fluctuation amount at that frequency is greater than a predetermined value. In such cases, it can be said that tooth skipping or other problems are occurring in the unit corresponding to that frequency.

[0067] Figure 13 is a flowchart illustrating the processing performed by a color image forming apparatus according to Embodiment 2 of the present invention. The processing shown in this flowchart is achieved by the CPU 32 of the controller 31 executing a program stored in the ROM 32a. In Figure 13, the same processing as in Figure 10 is given the same reference number.

[0068] When this process begins, CPU32 first performs an initial setup (n=0) in S201. This variable n is stored in RAM32b and counts the number of times the current value Iq flowing through motor A 101 is acquired. Next, in S102, CPU32 starts motor A 101, and in S103, when the rotation speed of motor A 101 reaches the target speed, the process proceeds to S104. In S104, CPU32 acquires the current value Iq_n flowing through motor A 101. Then, until a motor stop command is issued in S111, the CPU32 continues to acquire the current value of motor A 101 while incrementing the variable n by 1 in S106.

[0069] When a motor stop command is input, the process proceeds to S202, where the CPU32 performs frequency analysis on the waveforms Iq_0 to Iq_n, which are the current values ​​of motor A 101 acquired in S104, and calculates the amplitude value for each frequency. Next, in S203, the CPU32 determines whether the amplitude value of the detected frequency is less than the allowable amplitude value in the table (not shown), based on a pre-prepared table that associates the frequencies of each unit with their allowable amplitude values. If it is less than the allowable amplitude value, it is OK; if it is greater than or equal to the allowable amplitude value, it is NG. The OK / NG determination is made for each unit. Then, in S204, the CPU32 determines whether there are any NGs. If there are no NGs, the process proceeds to S206, where it determines that there are no problems with the drive train for motor A 101, and terminates this process.

[0070] On the other hand, if the CPU 32 determines in S204 that there is a faulty part, it proceeds to S205 to determine whether the faulty part is a part that can be replaced by the user. If it determines that the faulty part is a part that can be replaced by the user, it proceeds to S207 to notify the user of the reinstallation of the target unit via the display panel 33, etc., and terminates this process. If the CPU 32 determines in S205 that the faulty part is not a part that can be replaced by the user, it proceeds to S208 to notify the user of the malfunction of the target unit and terminates this process. In the case of S208, the user will notify a service technician and request that the service technician inspect the drive train, etc.

[0071] In Embodiment 2, an example was described in which malfunctions of the drive train or unit of motor A 101 are detected, but the present invention is not limited to this. For example, any value obtained by frequency analysis of the current value of motor A 101, such as detecting rotational irregularities in the commutation period of motor A 101 itself or oscillations in the control, is acceptable and is not limited to the description in Embodiment 2. Furthermore, objects other than motor A 101 may also be detected.

[0072] As described above, Embodiment 2 makes it possible to identify the malfunctioning unit or gear within the drive train and load of the A motor. This has the effect of allowing the user to reinstall the unit that can be replaced by the user, or to request inspection work on the drive train by a service technician.

[0073] (Other embodiments) The present invention can also be realized by supplying a program that implements one or more of the functions of the above-described embodiments to a system or device via a network or storage medium, and by having one or more processors in the computer of that system or device read and execute the program. It can also be realized by a circuit (e.g., an ASIC) that implements one or more functions.

[0074] This specification and drawings disclose the following image forming apparatus and control method thereof.

[0075] <Item 1> At least one motor and A motor control unit that rotates the motor, A drive transmission means for transmitting the driving force of the motor to the load, A detection means for detecting torque generated when the driving force is transmitted to the load by the drive transmission means, An acquisition means for acquiring the amplitude of the torque detected by the detection means, A determination means that determines that there is an abnormality in the load or the drive transmission means when the amplitude of the torque acquired by the acquisition means exceeds a predetermined value, An image forming apparatus characterized by having

[0076] <Item 2> The image forming apparatus according to item 1, characterized in that the acquisition means obtains a maximum value and a minimum value from a plurality of torques detected multiple times by the detection means, takes the difference between the maximum value and the minimum value as the torque amplitude, and further acquires the average value of the plurality of torque amplitudes detected multiple times by the detection means as the torque amplitude.

[0077] <Item 3> The image forming apparatus according to item 1 or 2, characterized in that the detection means detects the torque based on the current value flowing through the motor.

[0078] <Item 4> The image forming apparatus according to any one of items 1 to 3, characterized in that the load includes a unit that can be removed by the user.

[0079] <Item 5> The image forming apparatus according to item 4, characterized in that the removable unit includes a cartridge.

[0080] <Item 6> The image forming apparatus according to item 4, characterized in that the removable unit includes a fuser.

[0081] <Item 7> The image forming apparatus according to any one of items 1 to 6, further comprising a notification means for notifying the user in response to the determination means determining that an abnormality has occurred.

[0082] <Item 8> The system further includes detection means for detecting the attachment or detachment of the user-removable unit, The image forming apparatus according to item 7, characterized in that, after the detection means detects the installation of the removable unit, if the determination means determines that the torque amplitude exceeds a predetermined value, the notification means notifies that the cause of the abnormality is the removable unit.

[0083] <Item 9> The system further includes a frequency analysis means for frequency analysis of the torque waveform detected by the detection means, The image forming apparatus according to any one of items 1 to 8, characterized in that the acquisition means acquires the amplitude of the torque for each frequency.

[0084] <Item 10> The image forming apparatus according to item 9, further characterized in that the determination means determines whether the abnormality is occurring in the load or the drive transmission means based on the amplitude of the torque for each frequency.

[0085] <Item 11> The image forming apparatus according to any one of items 1 to 10, characterized in that the motor is a brushless motor.

[0086] <Item 12> The image forming apparatus according to any one of items 1 to 11, characterized in that the motor is driven by vector control.

[0087] <Item 13> A control method for an image forming apparatus having at least one motor, a motor control unit for rotating the motor, and a drive transmission means for transmitting the driving force of the motor to a load, The detection means includes a detection step of detecting the torque generated when the driving force is transmitted to the load by the drive transmission means, The acquisition means includes an acquisition step of acquiring the amplitude of the torque detected in the detection step, A determination means determines that if the amplitude of the torque acquired in the acquisition step exceeds a predetermined value, there is an abnormality in the load or the drive transmission means. A control method characterized by having the following features.

[0088] <Item 14> The control method according to item 13, further comprising a notification step that notifies the user in response to the determination step determining that the determination step is abnormal.

[0089] <Item 15> The detection means further includes a detection step for detecting the attachment or detachment of the user-removable unit, The control method according to item 14, characterized in that, after the detection step detects the installation of the removable unit, if the determination step determines that the torque amplitude exceeds a predetermined value, the notification step notifies that the cause of the abnormality is the removable unit.

[0090] <Item 16> The frequency analysis means further includes a frequency analysis step for frequency analysis of the torque waveform detected in the detection step, The control method according to any one of items 13 to 15, characterized in that the acquisition step acquires the amplitude of the torque for each frequency.

[0091] <Item 17> The control method according to item 16, further characterized in that the determination step determines whether the abnormality is occurring in the load or the drive transmission means based on the amplitude of the torque for each frequency.

[0092] The present invention is not limited to the embodiments described above, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, the following claims are attached to make the scope of the invention public. [Explanation of symbols]

[0093] 101…A motor, 13Y, 13M, 13C, 13K…photoconductor, 130Y, 130M, 130C, 130K…interface gear, 131Y, 131M, 131C, 131K…photoconductor gear, 30…fuser, 31…printer control unit, 32…CPU, 110…motor control unit, 201…microcontroller, 204…counter, 205…non-volatile memory, 207…memory, 209…current value calculation unit, 213…U-phase coil, 214…V-phase coil, 215…W-phase coil, 216…current detection unit, 217…UVW-phase output unit, 218…amplifier, 219, 220, 221…current detection resistor, 303…Iq frequency analysis unit

Claims

1. At least one motor and A motor control unit that rotates the motor, A drive transmission means for transmitting the driving force of the motor to the load, A detection means for detecting torque generated when the driving force is transmitted to the load by the drive transmission means, An acquisition means for acquiring the amplitude of the torque detected by the detection means, A determination means that determines that there is an abnormality in the load or the drive transmission means when the amplitude of the torque acquired by the acquisition means exceeds a predetermined value, An image forming apparatus characterized by having the following features.

2. The image forming apparatus according to claim 1, characterized in that the acquisition means obtains a maximum value and a minimum value from a plurality of torques detected multiple times by the detection means, takes the difference between the maximum value and the minimum value as the torque amplitude, and further acquires the average value of the plurality of torque amplitudes detected multiple times by the detection means as the torque amplitude.

3. The image forming apparatus according to claim 1, characterized in that the detection means detects the torque based on the current value flowing through the motor.

4. The image forming apparatus according to claim 1, characterized in that the load includes a user-removable unit.

5. The image forming apparatus according to claim 4, characterized in that the removable unit includes a cartridge.

6. The image forming apparatus according to claim 4, characterized in that the removable unit includes a fuser.

7. The image forming apparatus according to any one of claims 1 to 6, further comprising a notification means for notifying the user in response to the determination means determining that an abnormality has occurred.

8. The system further includes detection means for detecting the attachment or detachment of the user-removable unit, The image forming apparatus according to claim 7, characterized in that, after the detection means detects the installation of the removable unit, if the determination means determines that the torque amplitude exceeds a predetermined value, the notification means notifies that the cause of the abnormality is the removable unit.

9. The system further includes a frequency analysis means for frequency analysis of the torque waveform detected by the detection means, The image forming apparatus according to claim 1, characterized in that the acquisition means acquires the amplitude of the torque for each frequency.

10. The image forming apparatus according to claim 9, further characterized in that the determination means determines whether the abnormality is occurring in the load or the drive transmission means based on the amplitude of the torque for each frequency.

11. The image forming apparatus according to claim 1, characterized in that the motor is a brushless motor.

12. The image forming apparatus according to claim 1, characterized in that the motor is driven by vector control.

13. A control method for an image forming apparatus having at least one motor, a motor control unit for rotating the motor, and a drive transmission means for transmitting the driving force of the motor to a load, The detection means includes a detection step of detecting the torque generated when the driving force is transmitted to the load by the drive transmission means, The acquisition means includes an acquisition step of acquiring the amplitude of the torque detected in the detection step, A determination means determines that if the amplitude of the torque acquired in the acquisition step exceeds a predetermined value, there is an abnormality in the load or the drive transmission means. A control method characterized by having the following features.

14. The control method according to claim 13, further comprising a notification step of notifying the user in response to the determination step determining that the determination step is abnormal.

15. The detection means further includes a detection step for detecting the attachment or detachment of the user-removable unit, The control method according to claim 14, characterized in that, after the detection step detects the installation of the removable unit, if the determination step determines that the torque amplitude exceeds a predetermined value, the notification step notifies that the cause of the abnormality is the removable unit.

16. The frequency analysis means further includes a frequency analysis step for performing frequency analysis on the torque waveform detected in the detection step. The control method according to claim 13, characterized in that the acquisition step acquires the amplitude of the torque for each frequency.

17. The control method according to claim 16, further characterized in that the determination step determines whether the abnormality is occurring in the load or the drive transmission means based on the amplitude of the torque for each frequency.

Images