Image forming apparatus

Abstract

To drive a plurality of rollers with one motor.SOLUTION: An image forming apparatus comprises: at least one or more developing rollers; an A motor that drives the at least one or more developing rollers; a current detection unit (current value calculation unit 128) that detects the value of current flowing in the A motor; and a display panel that displays information on the state of the at least one or more developing rollers. The image forming apparatus detects the current value with the current detection unit, while driving the at least one or more developing rollers with the A motor, when the current value is a first value, information indicating that the at least one or more developing rollers are in an abnormal state is not displayed on the display panel, and when the current value is a second value larger than the first value, the information indicating that the at least one or more developing rollers are in the abnormal state is displayed on the display panel.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus such as a copying machine, a printer, or a facsimile apparatus, which includes a brushless motor.

Background Art

[0002] A brushless motor is used as a drive source for a rotating member of an image forming apparatus. Among brushless motors, a configuration having means for detecting an operating current of the motor and limiting the operating current has been proposed (see, for example, Patent Document 1). In recent years, due to the miniaturization of products of image forming apparatuses, the space available for brushless motors has become smaller than before, and it is required to miniaturize the motors while ensuring the necessary output. Therefore, it has been proposed to achieve miniaturization of the motor by designing it so as not to have much margin with respect to the required output. Further, when an unexpected overload occurs, it has been proposed to prevent a motor failure due to overheating or the like by stopping the motor by providing a limit to the current value.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the states of a plurality of rollers change. Even when the states of the plurality of rollers change, it is required to drive the plurality of rollers by one motor.

[0005] The present invention has been made under such circumstances, and an object thereof is to drive a plurality of rollers by one motor.

Means for Solving the Problems

[0006] In order to solve the above problems, the present invention comprises the following configuration. (1) A plurality of developing rollers and the A plurality of developing rollers as A single one for rotating a motor, A plurality of drive switching means provided corresponding to each of the plurality of developing rollers, for switching between transmission and non - transmission of the rotational driving force of the motor to the developing rollers detection means for detecting the value of the current flowing through the motor, Calculating means for calculating the torque value of each developing roller based on the current value detected by the detecting means the When the torque value of each developing roller calculated by the calculating means is greater than a threshold value, it is determined that the developing roller is overloaded, and the developing roller information regarding To the display means display Cause to of Control means, and is provided with The plurality of drive switching means are configured to switch between transmission and non - transmission of the developing rollers at different timings so that the plurality of developing rollers start or stop rotating at different timings. The calculating means calculates the torque value of each developing roller from the change in the current value acquired by the detecting means before and after the timing when the rotational driving force is switched from non - transmission to transmission or from transmission to non - transmission to the developing rollers by the plurality of drive switching means an image forming apparatus characterized by 。

Advantages of the Invention

[0007] According to the present invention, a plurality of rollers can be driven by one motor.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Modes for Carrying Out the Invention

[0009] Hereinafter, modes for carrying out the present invention will be described in detail with reference to the drawings by way of examples.

Examples

[0010] [Image Forming Apparatus] Hereinafter, Example 1 will be described with reference to FIGS. 1 to 5. However, Example 1 is merely an example, and the present invention is not limited to these configurations. FIG. 1 is a configuration diagram of an image forming apparatus such as a tandem type color laser printer using an electrophotographic process. Using FIG. 1, the image forming operation will be described with respect to the configuration of the image forming apparatus. The tandem type color image forming apparatus is configured to be able to output a full-color image by overlapping four colors of toner: yellow (Y), magenta (M), cyan (C), and black (K). And for each color For image formation, laser scanners 11Y, 11M, 11C, 11K and cartridges 12Y, 12M, 12C, 12K are provided. Hereinafter, unless otherwise stated when describing members related to a specific color, the subscripts Y, M, C, K of the reference signs will be omitted.

[0011] The cartridge 12 includes a photosensitive drum 13 that rotates in the direction of the arrow (clockwise direction) in FIG. 1, a photosensitive drum cleaner 14 provided in contact with the photosensitive drum 13, a charging roller 15, and a developing device having a developing roller 16. Further, an intermediate transfer belt 19 is provided in contact with the photosensitive drums 13 of each color, and a primary transfer roller 18 is installed so as to sandwich the intermediate transfer belt 19 and face each other.

[0012] The image forming apparatus has an A motor 101 (motor), which will be described later with reference to FIG. 2, for rotating the developing roller 16, which is one or more rotors. The image forming apparatus also has a B motor (not shown) for rotating the photosensitive drums 13Y, 13M, 13C, and a C motor (not shown) for rotating the intermediate transfer belt 19 and the photosensitive drum 13K. The A motor 101, the B motor, and the C motor are all DC brushless motors, and the motors that rotate each roller are not limited to those in Example 1.

[0013] On the downstream side in the conveyance direction of the cassette 22 that stores the paper 21, a paper feed roller 25, separation rollers 26a and 26b, and a registration roller (hereinafter referred to as a registration roller) 27 are provided. Near the downstream side in the conveyance direction of the registration roller 27, a conveyance sensor 28 is provided. Further downstream in the conveyance path, a secondary transfer roller 29 is disposed so as to be in contact with the intermediate transfer belt 19, and a fixing device 30 is disposed downstream of the secondary transfer roller 29. The printer control unit 31 is a control unit of the image forming apparatus, and is composed of a CPU (Central Processing Unit) 32 having a ROM 32a, a RAM 32b, a timer 32c, etc., and various input / output control circuits (not shown). The display panel 33, which is a display unit, has a screen displayed by a signal from the CPU 32.

[0014] Next, the electrophotographic process will be briefly described. In the dark place inside the cartridge 12, the charging roller 15 uniformly charges the surface of the photosensitive drum 13. The photosensitive drums 13Y, 13M, and 13C are configured to rotate when the driving force of the B motor is transmitted by gears. Similarly, the photosensitive drum 13K and the intermediate transfer belt 19 are configured to rotate when the driving force of the C motor is transmitted by gears.

[0015] Next, laser light modulated according to the image data by the laser scanner 11 is irradiated onto the surface of the photosensitive drum 13, and the electrostatic latent image is formed on the surface of the photosensitive drum 13 by removing the charged charges in the irradiated portion. In the developing device, toner is attached to the electrostatic latent image on the photosensitive drum 13 by the developing voltage from the developing roller 16 that holds a certain amount of toner layer, so that toner images of each color are formed on the surface of the photosensitive drum 13.

[0016] The toner image formed on the surface of the photosensitive drum 13 is attracted to the intermediate transfer belt 19 by the primary transfer voltage applied to the primary transfer roller 18 at the nip between the photosensitive drum 13 and the intermediate transfer belt 19. Further, the CPU 32 controls the image formation timing in each cartridge 12 at a timing corresponding to the conveyance speed of the intermediate transfer belt 19, and sequentially transfers the respective toner images onto the intermediate transfer belt 19. As a result, a full-color image is finally formed on the intermediate transfer belt 19.

[0017] On the other hand, the paper 21 in the cassette 22 is conveyed onto the conveyance path by the paper feed roller 25, and only one sheet of the paper 21 passes through the registration roller 27 by the separation rollers 26a and 26b and is conveyed to the secondary transfer roller 29. Thereafter, the toner image on the intermediate transfer belt 19 is transferred to the paper 21 at the nip between the secondary transfer roller 29 downstream of the registration roller 27 and the intermediate transfer belt 19, and an unfixed toner image is formed on the paper 21. Finally, the unfixed toner image on the paper 21 is subjected to heat fixing processing by the fixing device 30 and discharged outside the image forming apparatus. The image forming apparatus includes, for example, an environmental temperature sensor 40 that measures the environmental temperature of the outside air, and can perform image formation settings according to the measured environmental temperature.

[0018] [Drive Configuration] Next, a drive configuration for rotating the developing roller 16 will be described with reference to FIG. 2. The drive configuration for rotating the developing roller 16 is composed of an A motor 101, drive transmissions YA, YB, MA, MB, CA, CB, KA, KB by a gear train, and a D motor 104. Further, the drive configuration for rotating the developing roller 16 is composed of mechanical clutches 105Y, 105M, 105C, 105K which are transmission means controlled by the D motor 104.

[0019] Motor A 101 is a brushless motor. The rotational force generated in Motor A 101 is transmitted to mechanical clutches 105Y, 105M, 105C, and 105K through drive transmissions YA, MA, CA, and KA by a gear train respectively. Motor D 104 is a motor capable of rotational position control (e.g., a stepping motor). When Motor D 104 is rotated by a predetermined number of rotations, the driving force transmitted from Motor A 101 to mechanical clutches 105Y, 105M, 105C, and 105K is sequentially transmitted to developing rollers 16Y, 16M, 16C, and 16K through drive transmissions YB, MB, CB, and KB. As a result, developing rollers 16Y, 16M, 1 6C, and 16K rotate. Motor D 104 functions as a switching means for switching between a transmission state in which mechanical clutches 105Y, 105M, 105C, and 105K transmit the driving force of Motor A 101 to developing rollers 16Y, 16M, 16C, and 16K and a non - transmission state in which the driving force is not transmitted.

[0020] (Motor A) Next, the motor configuration for rotating Motor A 101 will be described. FIG. 3 shows the configuration of motor control unit 120 which is a control means. First, motor control unit 120 will be described in more detail. Motor control unit 120 is a circuit for rotating Motor A 101. Motor control unit 120 includes, for example, a microcomputer (hereinafter referred to as a microcontroller) 121 which is an arithmetic processing means. Microcontroller 121 incorporates a communication port 122, an AD converter 129, a counter 123, a non - volatile memory 124, a reference clock generation unit 125, a PWM port 127, and a current value calculation unit 128.

[0021] Counter 123 performs a counting operation based on the reference clock generated by the reference clock generation unit 125 based on the frequency signal of the crystal oscillator 126, and measures the period of the input pulse signal and generates a PWM signal according to the count value. The PWM port 127, which is the output means, has six terminals and outputs PWM signals of three high-side signals (U-H, V-H, W-H) and three low-side signals (U-L, V-L, W-L). The motor control unit 120 includes a three-phase inverter 131 composed of three high-side and three low-side switching elements. As the switching element, for example, a transistor or a field effect transistor (hereinafter referred to as FET) can be used. Each switching element is connected to the PWM port 127 via a gate driver 132 and can be controlled to be on or off (ON / OFF) by the PWM signal output from the PWM port 127. Each switching element is assumed to be on when the PWM signal is at a high level (hereinafter referred to as H) and off when at a low level (hereinafter referred to as L), but the reverse may also be true.

[0022] The U, V, and W phase outputs 133 of the inverter 131 are respectively connected to the coils 135, 136, and 137 of the A motor 101, and the current flowing through each coil 135, 136, and 137 (hereinafter referred to as coil current) can be controlled. The coil current flowing through each coil 135, 136, and 137 is detected by the current detection unit which is the detection means. The current detection unit is composed of a current sensor 130, an amplifier unit 134, an AD converter 129, and a current value calculation unit 128. First, the current flowing through the coils 135, 136, and 137 is converted into a voltage by the current sensor 130. The voltage converted by the current sensor 130 is amplified and an offset voltage is applied by the amplifier unit 134 and input to the AD converter 129 of the microcomputer 121. For example, if the current sensor 130 outputs a voltage of 0.01 V per 1 A, the amplification factor in the amplifier unit 134 is 10 times, and the applied offset voltage is 1.6 V, the output voltage of the amplifier unit 134 when a current of -10 A to +10 A flows is 0.6 to 2.6 V.

[0023] The AD converter 129 converts a voltage of 0 to 3V, which is an analog value, into a digital value of 0 to 4095 and outputs it. Therefore, when a current of -10A to +10A flows, the digital value is approximately 819 to 3549. Note that the positive and negative of the current are defined as positive when the current flows from the three-phase inverter 131 to the A motor 101. The current value calculation unit 128 performs a predetermined calculation on the analog-to-digital (hereinafter referred to as AD) converted data (hereinafter referred to as AD value) to calculate the current value. That is, the current value calculation unit 128 subtracts the offset value from the AD value and further multiplies it by a predetermined coefficient to obtain the current value. The offset value is the AD value of the offset voltage of 1.6V, so it is approximately 2184, and the predetermined coefficient is approximately 0.00733. The offset value is obtained by reading the AD value when no coil current is flowing, storing it in a temporary storage unit (not shown), and using it. The coefficient is stored in advance in the non-volatile memory 124 as a standard coefficient.

[0024] The microcomputer 121 controls the three-phase inverter 131 via the gate driver 132 to cause current to flow through the coils 135, 136, and 137 of the A motor 101. The microcomputer 121 detects the current flowing through the coils 135, 136, and 137 by the current sensor 130, the amplifier unit 134, and the AD converter 129, and calculates the rotor position and speed of the A motor 101 from the detected current flowing through the coils 135, 136, and 137. Thus, the microcomputer 121 can control the rotation of the A motor 101. The communication port 122 transmits and receives information to and from the printer control unit 31 via, for example, a serial communication line.

[0025] [Structure of A Motor] Subsequently, the structure of the A motor 101 will be described with reference to FIG. 4(a). The A motor 101 includes a 6-slot stator 140 and a 4-pole rotor 141. The stator 140 includes U-phase, V-phase, and W-phase coils 135, 136, and 137 wound around the stator core. The rotor 141 is composed of permanent magnets and has two sets of N poles / S poles. Each of the U-phase, V-phase, and W-phase coils 135, 136, and 137 is connected to the inverter 131.

[0026] [Operation of Motor A and Developing Roller] Subsequently, with reference to FIG. 4(b), the operation of motor A 101, which is a characteristic part of Example 1, and the developing roller 16 that is the load of motor A 101 will be described. FIG. 4(b) shows the transition of the torque of motor A 101 in (i), the transition of the speed of motor A 101 in (ii). (iii) shows the transition of the rotation of developing roller 16Y, (iv) shows the transition of the rotation of developing roller 16M, (v) shows the transition of the rotation of developing roller 16C, and (vi) shows the transition of the rotation of developing roller 16K. In the transition of the rotation of developing roller 16, the non-rotating state is represented at a low level, and the rotating state is shown at a high level. The horizontal axis in each case indicates time, and A to J indicate timings.

[0027] First, at timing A, the motor control unit 120 starts motor A 101 in a non-connected state where motor A 101 and all developing rollers 16 are not connected. Subsequently, the motor control unit 120 rotates motor D 104 when motor A 101 reaches a predetermined speed, and at timing B, connects mechanical clutch 105Y to start the rotation of developing roller 16Y. Similarly, the motor control unit 120 starts the rotation of developing rollers 16M, 16C, and 16K by connecting mechanical clutches 105M, 105C, and 105K at timings C, D, and E, respectively. The torque applied to motor A 101 increases sequentially at timings B, C, D, and E as shown in (i). The motor control unit 120 switches each mechanical clutch 105 to a transmission state at different timings so that each developing roller 16 starts rotating at different timings by means of motor D 104.

[0028] After the print job is completed, the motor control unit 120 rotates the D motor 104 to bring the mechanical clutches 105Y, 105M, 105C, and 105K into a disconnected state where they are sequentially disconnected at timings F, G, H, and I. As a result, the rotation of the developing rollers 16Y, 16M, 16C, and 16K sequentially stops. The torque applied to the A motor 101 gradually decreases at timings F, G, H, and I as shown in (i). Finally, the motor control unit 120 controls to stop the rotation of the A motor 101 at timing J. With such a configuration, even if there is only one motor, it is possible to sequentially start the rotation of the developing rollers 16Y, 16M, 16C, and 16K immediately before image formation at each station and sequentially end the rotation immediately after image formation. The motor control unit 120 switches the mechanical clutches 105 to a non-transmission state at different timings by the D motor 104 so that the respective developing rollers 16 stop rotating at different timings. Note that a predetermined number of printing operations are performed between timing E and timing F.

[0029] The amount of torque variation (hereinafter referred to as torque variation amount) applied to the A motor 101 at timings B, C, D, and E in this sequence is the torque corresponding to the developing rollers 16Y, 16M, 16C, and 16K. Also, the torque variation amount applied to the A motor 101 at timings F, G, H, and I is also the torque corresponding to the developing rollers 16Y, 16M, 16C, and 16K. Therefore, by detecting the torque variation amount applied to the A motor 101, it is possible to detect the torques of the developing rollers 16Y, 16M, 16C, and 16K respectively.

[0030] [Method for calculating torque of developing roller] A method for calculating the torque of each of the developing rollers 16Y, 16M, 16C, and 16K in Example 1 will be described with reference to FIG. 5(a). FIG. 5(a) is a graph showing time on the horizontal axis and the current value of the A motor 101 on the vertical axis. Points A to J on the graph correspond to timings A to J in FIG. 4(b). As described with reference to FIG. 4(b), the motor control unit 120 starts the rotation of the D motor 104, thereby connecting the mechanical clutch 105Y at timing B and starting the rotation of the developing roller 16Y. Similarly, the motor control unit 120 starts the rotation of the developing rollers 16M, 16C, and 16K by connecting the mechanical clutches 105M, 105C, and 105K at timings C, D, and E, respectively. As shown in FIG. 4(b)(i), since the torque applied to the A motor 101 increases at the timing when each developing roller 16 starts to rotate, the current value increases at the timing when each developing roller 16 starts to rotate as shown in FIG. 5(a).

[0031] The motor control unit 120 calculates the current value flowing through the A motor 101 by the current value calculation unit 128. The CPU 32 of the printer control unit 31 acquires the current value calculated by the current value calculation unit 128 from the motor control unit 120. Here, the average value of the current values between timing A and timing B (hereinafter referred to as the current average value) is defined as AVE_AB, and the current average value between timing B and timing C is defined as AVE_BC. Also, the current average value between timing C and timing D is defined as AVE_CD, and the current average value between timing D and timing E is defined as AVE_DE. Further, the current average value for a predetermined time, for example, several seconds, from timing E is defined as AVE_AFE. Values corresponding to the torque of each developing roller 16 on the A motor 101 axis (hereinafter referred to as torque equivalent values) Ty1, Tm1, Tc1, and Tk1 can be expressed by the following equations (1) to (4). The CPU 32 obtains the current average value from the acquired current value and obtains the torque equivalent value from the current average value. Ty1 = Kt × (AVE_BC - AVE_AB) Equation (1) Tm1 = Kt × (AVE_CD - AVE_BC) Equation (2) Tc1 = Kt × (AVE_DE - AVE_CD) Equation (3) Tk1 = Kt × (AVE_AFE - AVE_DE) Equation (4) Kt: Torque constant Thus, the difference in the current values (specifically, the average current value) before and after the transition of the mechanical clutch 105 from the non-transmission state to the transmission state and the torque equivalent value are in a proportional relationship.

[0032] In the above, the torque equivalent values Ty1, Tm1, Tc1, and Tk1 are calculated by multiplying the average current value by the torque constant Kt, and the torques of the developing rollers 16Y, 16M, 16C, and 16K are calculated. However, in this embodiment, a method of using the results of obtaining the absolute current values such as AVE_AB, AVE_BC, AVE_CD, AVE_DE, and AVE_AFE, that is, the combined current value of a plurality of developing rollers, and the differences between AVE_BC and AVE_AB, AVE_CD and AVE_BC, AVE_DE and AVE_CD, AVE_AFE and AVE_DE, etc., the current values corresponding to the developing rollers 16Y, 16M, 16C, and 16K for subsequent determination is also effective.

[0033] After a predetermined number of prints are completed, the motor control unit 120 restarts the rotation of the D motor 104, disconnects the mechanical clutch 105Y at timing F, and stops the rotation of the developing roller 16Y. Similarly, the motor control unit 120 disconnects the mechanical clutches 105M, 105C, and 105K at timings G, H, and I respectively, thereby stopping the rotation of the developing rollers 16M, 16C, and 16K. As shown in FIG. 4(b)(i), since the torque applied to the A motor 101 decreases at the timing when each developing roller 16 stops rotating, the current value decreases at the timing when the developing roller 16 starts to stop as shown in FIG. 5(a). Let the average current value for a predetermined time before timing F, for example, several seconds, be AVE_BFF. Also, let the average current value between timing F and timing G be AVE_FG, the average current value between timing G and timing H be AVE_GH, the average current value between timing H and timing I be AVE_HI, and the average current value between timing I and timing J be AVE_IJ. The torque equivalent values Ty2, Tm2, Tc2, and Tk2 of each developing roller 16 on the A motor 101 axis can be expressed by the following equations (5) to (8). Ty2 = Kt × (AVE_BFF - AVE_FG) Equation (5) Tm2 = Kt × (AVE_FG - AVE_GH) Equation (6) Tc2 = Kt × (AVE_GH - AVE_HI) Equation (7) Tk2 = Kt × (AVE_HI - AVE_IJ) Equation (8) Kt: Torque constant Thus, the difference between the current values (specifically, the average current value) before and after the transition of the mechanical clutch 105 from the transmission state to the non - transmission state and the torque equivalent value are in a proportional relationship.

[0034] In the above, the torque equivalent values Ty2, Tm2, Tc2, and Tk2 are calculated by multiplying the average current value by the torque constant Kt, and the torques of the developing rollers 16Y, 16M, 16C, and 16K are calculated. However, in this embodiment, a method of using the absolute current values such as AVE_BFF, AVE_FG, AVE_GH, AVE_HI, AVE_IJ, that is, the total current value of a plurality of developing rollers, or the differences between AVE_BFF and AVE_FG, AVE_FG and AVE_GH, AVE_GH and AVE_HI, AVE_HI and AVE_IJ, etc., the results of obtaining the current values corresponding to the developing rollers 16Y, 16M, 16C, and 16K for subsequent determination is also effective.

[0035] As described above, the CPU 32 can calculate the torque equivalent values Ty1, Tm1, Tc1, and Tk1 of each developing roller 16 immediately before the start of printing and the torque equivalent values Ty2, Tm2, Tc2, and Tk2 of each developing roller 16 immediately after the end of printing. The CPU 32 functions as a calculating means for calculating the torque value of the developing roller 16 based on the current value when the D motor 104 is in the non-transmission state and the current value when it is in the transmission state. In the first embodiment, a configuration in which one motor (A motor 101) drives four developing rollers 16 has been described, but the present invention is not limited to the first embodiment, such as a configuration in which one photosensitive drum 13 and two developing rollers 16 are driven by one motor. That is, it is applicable to a configuration in which at least one or more rotors are driven by one motor.

[0036] [Example of using torque equivalent value] Subsequently, a specific example of using the torque equivalent value of each developing roller 16 in the first embodiment will be described with reference to FIG. 5(b). FIG. 5(b) illustrates an example of notifying the user which developing roller 16 is the cause of overcurrent after the A motor 101 has stopped due to overheat protection.

[0037] Fig. 5(b) is a graph showing time on the horizontal axis and the current value of the A motor 101 on the vertical axis. A to E indicate the above-described timings A to E. As shown in the above-described equations (1) to (8), the difference in the current value and the torque equivalent value before and after the transition of the mechanical clutch 105 from the non-transmission state to the transmission state or before and after the transition from the transmission state to the non-transmission state are in a proportional relationship. For this reason, in the graph of Fig. 5(b), the torque equivalent value is indicated by double arrows of a solid line for the difference in the current value (the stepped portion of the graph). Note that the double arrows of the broken line indicate a predetermined threshold value Tth which is the first threshold value described later. The representation of such a graph is the same as that in Fig. 7 of Example 2 described later. In Fig. 5(b), the current value which is the second threshold value when stopping the A motor 101 for overheat protection (hereinafter referred to as the overheat protection current threshold value) is indicated by a broken line. When the time during which the current value of the A motor 101 exceeds the overheat protection current threshold value of the A motor 101 is equal to or longer than a predetermined time, a protection operation works so that the current value or the operation of the A motor 101 is restricted in order to prevent damage to the A motor 101. When the time during which the current value of the A motor 101 exceeds the overheat protection current threshold value of the A motor 101 is equal to or longer than a predetermined time, in Example 1, for example, the A motor 101 is stopped.

[0038] As described with reference to Fig. 5(a), the motor control unit 120 starts the rotation of each developing roller 16 during the period from timing A to timing E, and the CPU 32 calculates the torque equivalent values Ty1, Tm1, Tc1, and Tk1 of each developing roller 16 immediately before the start of printing. Thereafter, when the state in which the detected current value is equal to or higher than the overheat protection current threshold value continues for a predetermined time or more after timing E, the motor control unit 120 stops the A motor 101 in order to prevent damage to the A motor 101.

[0039] When the stop of motor A 101 occurs, among the torque equivalent values Ty1, Tm1, Tc1, and Tk1 of each developing roller 16 calculated immediately before, the developing roller 16 of the station that exceeds a predetermined threshold value Tth is hereinafter referred to as an overload developing roller. In FIG. 5(b), the torque equivalent value Ty1 of the developing roller 16Y is smaller than the predetermined threshold value Tth (Ty1 < Tth). The torque equivalent value Tc1 of the developing roller 16C is smaller than the predetermined threshold value Tth (Tc1 < Tth). The torque equivalent value Ty1 of the developing roller 16K is equal to the predetermined threshold value Tth (Tk1 = Tth). However, the torque equivalent value Tm1 of the developing roller 16M is larger than the predetermined threshold value Tth (Tm1 > Tth). That is, the CPU 32 of the printer control unit 31 identifies the developing roller 16M as the overload developing roller. The CPU 32 functions as a determination means for comparing the torque value of the developing roller with a predetermined threshold value determined in advance and determining the developing roller with a torque value larger than the predetermined threshold value as the overload developing roller. The CPU 32 notifies the user and the service technician of the information on the overload developing roller (the developing roller 16M in FIG. 5(b)) on the display panel 33 and / or the screen of the personal computer (hereinafter referred to as PC) to which the image forming apparatus is connected.

[0040] In the above, the method of obtaining the torque equivalent value and determining the overload has been described, but it is not limited thereto. For example, the CPU 32 determines that it is an overload developing roller when the result of obtaining the absolute value of the current such as AVE_AB, AVE_BC, AVE_CD, AVE_DE, AVE_AFE, that is, the total current value of a plurality of developing rollers, or the difference between AVE_BC and AVE_AB, the difference between AVE_CD and AVE_BC, the difference between AVE_DE and AVE_CD, the difference between AVE_AFE and AVE_DE, etc., corresponding to the current values of the developing rollers 16Y, 16M, 16C, 16K is larger than a predetermined threshold value, and notifies the user and the service technician of the information on the overload developing roller (the developing roller 16M in FIG. 5(b)) on the display panel 33 and / or the screen of the PC to which the image forming apparatus is connected.

[0041] By notifying the user and the service technician of the developing roller 16 that is overloaded, which is the cause of the failure as described above, it becomes possible to replace only the developing roller that is the cause of the failure without unnecessarily replacing the developing roller 16. In the first embodiment, when the torque equivalent value of each developing roller 16 exceeds a predetermined threshold value, it is set as the overloaded developing roller. However, the method for determining the overloaded developing roller is not limited to the first embodiment, such as setting the developing roller 16 with the highest torque as the overloaded developing roller.

[0042] [Judgment Process for Overloaded Developing Roller] Subsequently, the judgment process for the overloaded developing roller in the first embodiment will be described with reference to the flowchart in FIG. 6. When the notification sequence and the print sequence for the overloaded developing roller are started, the CPU 32 starts the processes from step (hereinafter referred to as S) 101 and below. In S101, the CPU 32 activates the A motor 101 by the motor control unit 120. In S102, the CPU 32 determines whether the activation of the A motor 101 has been completed via the motor control unit 120. If, in S102, the CPU 32 determines that the activation of the A motor 101 has not been completed, the process returns to S102. If it determines that the activation of the A motor 101 has been completed, the process proceeds to S103.

[0043] In S103, the CPU 32 starts the rotation of the D motor 104 by the motor control unit 120. In S104, the CPU 32 acquires current values to obtain the average current value AVE_AB of the A motor 101 from timing A. In S105, the CPU 32 monitors the current value of the A motor 101 to determine whether it has detected that timing B has occurred based on the change in the current value. Here, as shown in Fig. 5(a), the change in the current value is the change in the current value associated with the connection of the developing roller 16Y. Also, assume that the value of the change in the current value when the developing roller 16Y is connected has been obtained in advance through experiments or the like and is stored in the ROM 32a or the like. The same shall apply to timings C, D, and E hereinafter. If the CPU 32 determines in S105 that timing B has not been detected, the process returns to S105, and if it determines that timing B has been detected, the process proceeds to S106. In S106, the CPU 32 obtains (calculates) the average current value AVE_AB of the A motor 101 from timing A.

[0044] In S107, the CPU 32 starts acquiring current values to obtain the average current value AVE_BC of the A motor 101 from timing B. In S108, the CPU 32 monitors the current value of the A motor 101 to determine whether it has detected that timing C has occurred based on the change in the current value. If the CPU 32 determines in S108 that timing C has not been detected, the process returns to S108, and if it determines that timing C has been detected, the process proceeds to S109. In S109, the CPU 32 obtains the average current value AVE_BC of the A motor 101 from timing B.

[0045] In S110, the CPU 32 starts acquiring current values to obtain the average current value AVE_CD of the A-motor 101 from timing C. In S111, the CPU 32 monitors the current value of the A-motor 101 to determine whether it has detected that timing D has occurred from the change in the current value. If the CPU 32 determines in S111 that timing D has not been detected, the process returns to S111. If it determines that timing D has been detected, the process proceeds to S112. In S112, the CPU 32 obtains the average current value AVE_CD of the A-motor 101 from timing C.

[0046] In S113, the CPU 32 starts acquiring current values to obtain the average current value AVE_DE of the A-motor 101 from timing D. In S114, the CPU 32 monitors the current value of the A-motor 101 to determine whether it has detected that timing E has occurred from the change in the current value. If the CPU 32 determines in S114 that timing E has not been detected, the process returns to S114. If it determines that timing E has been detected, the process proceeds to S115. In S115, the CPU 32 obtains the average current value AVE_DE of the A-motor 101 from timing D.

[0047] In S116, after a predetermined time has elapsed, the CPU 32 starts acquiring current values in order to obtain the average current value AVE_AFE of the A motor 101 from timing E. Also, the CPU 32 resets and starts the timer 32c. In S117, the CPU 32 refers to the timer 32c and determines whether or not the predetermined time has elapsed. In S117, if the CPU 32 determines that the predetermined time has not elapsed, the process returns to S117, and if it determines that the predetermined time has elapsed, the process proceeds to S118. In S118, the CPU 32 obtains the average current value AVE_AFE of the A motor 101 within the predetermined time from timing E. In S119, the CPU 32 determines whether or not the end process of a predetermined number of printing operations (print sequence) has been started. In S119, if the CPU 32 determines that the end process of the print sequence has been started, it determines that the operation is proceeding normally and the process proceeds to S125. In S119, if the CPU 32 determines that the end process of the print sequence has not been started, the process proceeds to S120.

[0048] In S120, the CPU 32 determines whether the A motor 101 has been stopped because the current value of the A motor 101 has been equal to or higher than the overheating protection current threshold for a predetermined time or more. That is, the CPU 32 determines whether the state of "the current value of the A motor 101 ≥ the overheating protection current threshold" has continued for a predetermined time or more and whether the A motor 101 has been stopped. If the CPU 32 determines in S120 that the A motor 101 has not been stopped, the process returns to S119. If the CPU 32 determines that the A motor 101 has been stopped, the process proceeds to S121. In S121, the CPU 32 calculates the torque equivalent values Ty1, Tm1, Tc1, and Tk1 of each developing roller 16 using the formulas (1), (2), (3), and (4) described in FIG. 5(a). In S122, the CPU 32 compares the torque equivalent values Ty1, Tm1, Tc1, and Tk1 of each developing roller 16 with a predetermined threshold value Tth, respectively. The CPU 32 designates the developing roller 16 of the station that has exceeded the predetermined threshold value Tth as an overload developing roller and identifies the overload developing roller. In S123, the CPU 32 displays the information of the overload developing roller identified in S122 on a screen such as a display panel 33 or a screen of a PC (not shown), etc., and ends the overload developing roller notification sequence. In S125, the CPU 32 starts the rotation of the D motor 104. As a result, the rotation of each developing roller 16 is sequentially stopped. In S126, the CPU 32 determines whether a predetermined time has elapsed. If the CPU 32 determines in S126 that the predetermined time has not elapsed, the process returns to S126. If the CPU 32 determines that the predetermined time has elapsed, the printing sequence ends.

[0049] In Example 1, the overloaded developing roller that is the cause of the failure was identified using the torque equivalent values Ty1, Tm1, Tc1, and Tk1 of each developing roller 16 immediately before the start of printing. However, the specific method, such as identifying the overloaded developing roller that is the cause of the failure using the torque equivalent values Ty2, Tm2, Tc2, and Tk2 of each developing roller 16 immediately after the end of printing, is not limited to Example 1. Also, in a configuration where a plurality of rollers are driven by one motor, other rollers may be used instead of being limited to the developing rollers. By notifying the user and the service technician of the overloaded roller that is the cause of the failure as described above, unnecessary replacement of the roller can be prevented, and only the roller that is the cause of the failure can be replaced.

[0050] As described above, according to Example 1, a plurality of rollers can be driven by one motor. Also, even in a configuration where a plurality of rollers are driven by one motor, the torque value of each roller can be obtained respectively.

Example

[0051] [Detection of signs of failure occurrence] In Example 1, an example of identifying the overloaded developing roller that is the cause of the failure after the A motor 101 stopped due to overheating protection was described. In Example 2, an example of notifying the signs before the stop of the A motor 101 occurs will be described. Example 2 determines the presence or absence of an overloaded developing roller even if the current value of the A motor 101 is above the overheating protection current threshold for less than a predetermined time or below the overheating protection current threshold, and identifies the developing roller 16 if there is an overloaded developing roller. Hereinafter, Example 2 will be mainly described with differences from Example 1, and the common configurations will be denoted by the same reference numerals and the description will be omitted. In FIG. 7, an example of notifying which developing roller 16 has a heavier torque than expected before the A motor 101 stops due to overheating protection will be described.

[0052] In FIG. 7, the horizontal axis represents time and the vertical axis represents the current value of the A motor 101. The dashed line is the temperature rise protection current threshold of the A motor 101. Timings A to J are the same as those in FIG. 5(a) and the like. Also in the second embodiment, when the time during which the current value of the A motor 101 exceeds the temperature rise protection current threshold continues for a predetermined time or longer, a protection operation works so that the current value or operation is restricted in order to prevent damage to the A motor 101. As described with reference to FIG. 5(a), during the period from timing A to timing E, each developing roller 16 starts rotating, and the CPU 32 calculates the torque equivalent values Ty1, Tm1, Tc1, and Tk1 of each developing roller 16 immediately before the start of printing. The CPU 32 compares each torque equivalent value with a predetermined threshold value Tth determined in advance. When the torque equivalent value of each developing roller 16 is greater than the predetermined threshold value Tth, the CPU 32 identifies the developing roller 16 of that station as an overloaded developing roller.

[0053] After printing a predetermined number of sheets, during the period from timing F to timing J as described with reference to FIG. 5(a), each developing roller 16 stops rotating, and the CPU 32 calculates the torque equivalent values Ty2, Tm2, Tc2, and Tk2 of each developing roller 16 immediately after the end of printing. The CPU 32 compares each torque equivalent value with a predetermined threshold value Tth determined in advance. When the torque equivalent value of each developing roller 16 is greater than the predetermined threshold value Tth, the CPU 32 identifies the developing roller 16 of that station as an overloaded developing roller.

[0054] For example, in FIG. 7, the torque equivalent value Tm2 of the developing roller 16M immediately after the printing is completed is greater than a predetermined threshold value Tth (Tm2 > Tth). That is, in the next printing sequence, the A motor 101 may be stopped due to the developing roller 16M. This is regarded as a sign. The CPU 32 identifies the developing roller 16M as an overloaded developing roller. The CPU 32 notifies the user and the service technician on the display panel 33 and / or the screen of a PC (not shown) etc. that there is a possibility of causing an over-temperature rise of the A motor 101 in the future together with the fact that the developing roller is overloaded. The user and the service technician can arrange a new developing roller 16 etc. in advance before the A motor 101 stops due to the abnormality of the developing roller 16. In addition, if there is an overloaded developing roller before the start of printing in a state where the current value of the A motor 101 is less than the over-temperature protection current threshold value for less than a predetermined time or less than the over-temperature protection current threshold value and the A motor 101 has not been stopped, the printing operation is continued. The CPU 32 displays the information of the overloaded developing roller on the display panel 33 etc. while continuing the printing operation.

[0055] In the second embodiment, the CPU 32 compares the torque equivalent values Ty1, Tm1, Tc1, Tk1 of each developing roller 16 immediately before the start of printing and the torque equivalent values Ty2, Tm2, Tc2, Tk2 of each developing roller 16 immediately after the printing is completed with predetermined threshold values prepared in advance. The CPU 32 has described an example in which the developing roller 16 of that station is regarded as an overloaded developing roller when the torque equivalent value of each developing roller 16 is greater than the predetermined threshold value. However, the ratio of the torque equivalent value of each developing roller 16 to the predetermined threshold value determined in advance may be notified on the display panel 33 and / or the screen of a PC (not shown) etc. for each station. That is, the CPU 32 may compare the torque value of the developing roller 16 with the predetermined threshold value determined in advance and determine that it is an overloaded developing roller based on the ratio of the torque value to the predetermined threshold value. Thus, the calculation method and the display method on the display panel 33 and / or the screen of the PC are not limited to the second embodiment.

[0056] [Judgment Process of Overload Developing Roller] Regarding the control for explaining the second embodiment, it will be described with reference to the flowchart of FIG. 8. Note that the processes from S101 to S118 are the same in order and the same processes as those described in FIG. 6, so the description will be omitted. In the second embodiment, when five current average values are calculated, the process proceeds to the process of S121. In S121, the CPU 32 calculates the torque equivalent values Ty1, Tm1, Tc1, and Tk1 of each developing roller 16. In S122, the CPU 32 compares each torque equivalent value calculated in S121 with a predetermined threshold value Tth, and identifies the developing roller of the station that has exceeded the predetermined threshold value Tth as an overload developing roller. Note that when there is no overload developing roller, information of "none" is retained. In S201, the CPU 32 determines whether there is an overload developing roller. In S201, when the CPU 32 determines that there is an overload developing roller, the process proceeds to S123, and when it determines that there is no overload developing roller, the process proceeds to S119. In S123, the CPU 32 displays the information of the overload developing roller on the display panel 33 and / or the screen of the PC (not shown), and the process proceeds to S119.

[0057] In S119, the CPU 32 determines whether the print sequence end process has started. In S119, when the CPU 32 determines that the print sequence end process has not started, the process proceeds to S120, and when it determines that the print sequence end process has started, the process proceeds to S125. In S120, the CPU 32 determines whether the A motor 101 has stopped for temperature rise protection. In S120, when the CPU 32 determines that the A motor 101 has not stopped, the process returns to S119, and when it determines that the A motor 101 has stopped, the process proceeds to S230. In S230, the CPU 32 displays the information of the overload developing roller on the display panel 33 or the like. Note that the information displayed in S123 is the information of the overload developing roller identified before the A motor 101 stops, and the information displayed in S230 is the information of the overload developing roller identified after the A motor 101 stops. When the information displayed in the process of S230 is the same as the information displayed in S123, the process of S230 may be omitted.

[0058] At S125, the CPU 32 starts the rotation of the D motor 104. At S202, the CPU 32 starts acquiring current values to obtain the average current value AVE_BFF of the A motor 101 before timing F. At S203, the CPU 32 monitors the current value of the A motor 101 to determine whether timing F is detected from the change in the current value. If the CPU 32 determines at S203 that timing F has not been detected, the process returns to S203. If it determines that timing F has been detected, the process proceeds to S204. At S204, the CPU 32 obtains the average current value AVE_BFF of the A motor 101 until timing F is detected.

[0059] At S205, the CPU 32 starts acquiring current values to obtain the average current value AVE_FG of the A motor 101 from timing F. At S206, the CPU 32 monitors the current value of the A motor 101 to determine whether timing G is detected from the change in the current value. If the CPU 32 determines at S206 that timing G has not been detected, the process returns to S206. If it determines that timing G has been detected, the process proceeds to S207. At S207, the CPU 32 obtains the average current value AVE_FG of the A motor 101 from timing F.

[0060] At S208, the CPU 32 starts acquiring current values to obtain the average current value AVE_GH of the A motor 101 from timing G. At S209, the CPU 32 monitors the current value of the A motor 101 to determine whether timing H is detected from the change in the current value. If the CPU 32 determines at S209 that timing H has not been detected, the process returns to S209. If it determines that timing H has been detected, the process proceeds to S210. At S210, the CPU 32 obtains the average current value AVE_GH of the A motor 101 from timing G.

[0061] In S211, the CPU 32 starts acquiring current values to obtain the average current value AVE_HI of the A motor 101 from timing H. In S212, the CPU 32 monitors the current value of the A motor 101 to determine whether timing I is detected from the change in the current value. If the CPU 32 determines in S212 that timing I has not been detected, the process returns to S212. If it determines that timing I has been detected, the process proceeds to S213. In S213, the CPU 32 obtains the average current value AVE_HI of the A motor 101 from timing H.

[0062] In S214, the CPU 32 completes acquiring current values to obtain the average current value AVE_IJ of the A motor 101 from timing I. The CPU 32 resets and starts the timer 32c. In S215, the CPU 32 determines whether a predetermined time has elapsed by referring to the timer 32c. If the CPU 32 determines in S215 that the predetermined time has not elapsed, the process returns to S215. If it determines that the predetermined time has elapsed, the process proceeds to S216. In S216, the CPU 32 obtains the average current value AVE_IJ of the A motor 101 until the predetermined time elapses from timing I. In S217, the CPU 32 calculates the torque equivalent values Ty2, Tm2, Tc2, and Tk2 of each developing roller 16. In S218, the CPU 32 compares the predetermined threshold value Tth with each torque equivalent value calculated in S217 and identifies the developing roller 16 of the station that exceeds the predetermined threshold value Tth as an overload developing roller. The developing roller 16 identified as an overload developing roller may cause the A motor 101 to stop in the next print sequence, and the CPU 32 regards this as a sign.

[0063] In S219, the CPU 32 determines whether there is an overloaded developing roller. If in S219 the CPU 32 determines that there is no overloaded developing roller, it ends the overloaded developing roller notification sequence and the printing sequence. If in S219 the CPU 32 determines that there is an overloaded developing roller, it advances the process to S220. In S220, the CPU 32 displays information on the overloaded developing roller on the display panel 33 and / or the screen of the PC (not shown), etc., and ends the overloaded developing roller notification sequence and the printing sequence.

[0064] As described above, information on the overloaded developing roller is notified to the user and the service technician on the display panel 33 and / or the screen of the PC (not shown), etc. Thereby, the user and the service technician can arrange a new developing roller, etc. in advance before the motor stops due to an abnormality of the developing roller. In addition, in the first and second embodiments, the CPU 32 (printer control unit 31) obtains the current average value and the torque equivalent value from the current value. However, a configuration may be adopted in which the motor control unit 120 obtains these and transmits the obtained information to the CPU 32. That is, the functions of the printer control unit 31 and the motor control unit 120 are not limited to the above-described embodiments. As described above, according to the second embodiment, a plurality of rollers can be driven by one motor. Also, in a configuration in which a plurality of rollers are driven by one motor, the torque value of each roller can be obtained.

[0065] [Regarding Other Modification Examples] In the above-described embodiments, when performing the notification process, the process related to the total load of the plurality of developing rollers 16 and the process related to the load of one developing roller 16 were described. However, in the configurations of the first and second embodiments, in the case of a plurality of developing rollers 16 as well as in the case of one developing roller 16, it is possible to perform the process using the current value instead of necessarily using the torque value. Also, in the case of a plurality of developing rollers 16 as well as in the case of one developing roller 16, it is possible to perform the process using the torque value. Furthermore, in the case of a plurality of developing rollers 16, it is also possible to perform the process using the current value for one of them and the torque value for the other.

[0066] While driving at least one developing roller 16 by the A motor 101, the current detection unit detects the current value. When the current value is the first value, information indicating that at least one developing roller 16 is in an abnormal state is not displayed on the display panel 33. On the other hand, when the detected current value is a second value greater than the first value, information indicating that at least one developing roller 16 is in an abnormal state is displayed on the display panel 33.

[0067] Furthermore, the following control can also be performed. Among at least one developing roller 16, the first current value is detected by the current detection unit in a state where a developing roller 16 of a predetermined color, which is the first rotating body, is not driven by the A motor 101. Also, the second current value is detected by the current detection unit in a state where the developing roller 16 of the predetermined color is driven by the A motor 101. Then, when the difference between the first current value and the second current value is the first value, control may be performed so that information indicating that the developing roller 16 of the predetermined color is in an abnormal state is not displayed on the display panel 33. On the other hand, when the difference between the first current value and the second current value is a second value greater than the first value, control may be performed so that information indicating that the developing roller 16 of the predetermined color is in an abnormal state is displayed on the display panel 33. Note that the first value is a value smaller than the above-described threshold value Tth, and the second value is a value greater than the first value and greater than the threshold value Tth. Also in these modified examples, a plurality of rollers can be driven by one motor.

Explanation of Reference Numerals

[0068] 16 Developing roller 101 A motor 19 CPU 33 Display panel

Claims

1. A plurality of developing rollers, a single motor for rotating the plurality of developing rollers, a plurality of drive switching means provided corresponding to each of the plurality of developing rollers for switching transmission and non - transmission of the rotational driving force of the motor to the developing rollers, a detection means for detecting a current value flowing through the motor, a calculation means for calculating a torque value of each developing roller based on the current value detected by the detection means, a control means for determining that the developing roller is overloaded when the torque value of each developing roller calculated by the calculation means is greater than a threshold value, and causing information regarding the developing roller to be displayed on a display means, comprising, the plurality of drive switching means are configured to switch transmission and non - transmission of the developing rollers at different timings so that the plurality of developing rollers start or stop rotating at different timings, the calculation means calculates the torque value of each developing roller from a change in the current value acquired by the detection means before and after the timing when the rotational driving force is switched from non - transmission to transmission, or from transmission to non - transmission, by the plurality of drive switching means. The image forming apparatus is characterized by this.

2. Among the plurality of developing rollers, a first current value is detected by the detection means in a state where the rotational driving force is non - transmitted to a first developing roller, and a second current value is detected by the detection means in a state where the rotational driving force is transmitted to the first developing roller. When the difference between the first current value and the second current value is a first value, information indicating that the first developing roller is in an abnormal state is not displayed on the display means. When the difference between the first current value and the second current value is a second value greater than the first value, information indicating that the first developing roller is in an abnormal state is displayed on the display means. The image forming apparatus according to claim 1 is characterized by this.

3. The image forming apparatus according to claim 1 or claim 2, wherein the control means controls the motor.

4. The calculation means calculates the torque value of the first developing roller based on a difference between an average value of current values detected by the detection means when the rotational driving force is not transmitted and an average value of current values detected by the detection means when the rotational driving force is transmitted. The image forming apparatus according to claim 2.

5. The control means stops the motor when a state in which the current value detected by the detection means is greater than the threshold value continues for a predetermined time or more. The image forming apparatus according to any one of claims 1 to 4.

6. The motor is a brushless motor. The image forming apparatus according to any one of claims 1 to 5.

7. The brushless motor includes a stator core, a stator having a coil wound around the stator core, and a rotor including a permanent magnet. The control means includes a switching element for passing a current through the coil and an output means for outputting a pulse for controlling on or off of the switching element. The image forming apparatus according to claim 6.

Images