JP6060068B2 - Motor drive device and image forming apparatus - Google Patents

Description

  The present invention relates to a motor drive device and an image forming apparatus, and more particularly to motor drive control.

  For example, image forming apparatuses such as multifunction peripherals, printers, copiers, and facsimile machines are provided with a toner motor for stirring, replenishing and transporting toner. Since the toner motor does not require precise speed control or torque control, for example, an inexpensive DC brush motor that can be driven only by on / off control of energization is often used as the toner motor.

  When the driving of the toner motor is started, first, the starting current increases beyond the electrical time constant Te (inrush current), and then the current starts to rotate and the current decreases and converges to a predetermined current. . That is, at normal times, the starting current of the toner motor converges to a predetermined current by continuously driving the toner motor with the switching elements such as transistors always on.

  On the other hand, in a low-temperature environment, an increase in load (decrease in toner fluidity) or the like may cause a start-up failure of the toner motor or an increase in start-up current (continuation of inrush current). At the time of start-up failure, even if an inrush current occurs, the current may not continue to decrease and may continue. In this case, the overcurrent continues to flow through the toner motor and the control device for a long time, so that the burden on them increases. Therefore, if the overcurrent state continues for a predetermined error detection time or longer when the toner motor is activated, an error process such as forcibly stopping the driving of the toner motor is performed by detecting the activation error.

  For example, Patent Document 1 below is an invention related to a power window drive control device for an automobile, but by gradually changing the detection reference value of the motor current from the start of driving the motor, the overcurrent flowing to the motor when the foreign object is caught in the power window is reduced. It can be detected.

JP 7-317433 A

  As described above, some image forming apparatuses have a function of detecting a start-up error when it is detected that an overcurrent state has continued for a predetermined error detection time or more. However, setting the error detection time to an optimum value is not possible. It is very difficult. For example, if the error detection time is too short, the frequency of startup error detection increases, which hinders normal drive control of the motor. On the other hand, if the error detection time is too long, there is a risk of damage to the device, so a control device with an overspec than the original specification must be used, which increases costs.

  The present invention has been made to solve the above-described problem, and an object of the present invention is to normally drive a motor without using an overspec control device for driving the motor.

A motor driving apparatus according to one aspect of the present invention includes an environmental temperature sensor that detects an environmental temperature, a motor that supplies a driving force to a driven object, and a motor control unit that controls the driving of the motor. The motor control unit detects a temperature equal to or lower than a predetermined temperature at the start of driving of the motor, and a predetermined time has elapsed since the previous driving stop of the motor. The motor is intermittently driven by energization with a driving time shorter than the electric time constant of the motor, and the maximum driving current of the motor at each driving time of the motor is predetermined. when below the first current value, the energization with a short driving time than the electric time constant is switched to the continuous energization, which drives the motor A.

  According to the present invention, the motor can be normally driven without using an overspec control device for driving the motor.

1 is a front sectional view showing a structure of an image forming apparatus according to an embodiment of the present invention. 2 is a functional block diagram illustrating a main internal configuration of the image forming apparatus. FIG. FIG. 3 is a schematic circuit diagram illustrating a control system of a toner motor. It is a graph showing the switch control signal which a motor control part outputs, and the time change of the starting current at the time of normal of a toner motor. It is a graph showing the time change of the starting electric current at the time of the switch control signal which a motor control part outputs, and the starting failure of a toner motor. 5 is a flowchart illustrating an embodiment of toner motor driving by a motor control unit. It is a graph showing the time change of the starting current at the time of normal of the conventional toner motor. It is a graph showing the time change of the starting current at the time of the starting failure of the conventional toner motor.

  Hereinafter, a motor drive device and an image forming apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a front sectional view showing the structure of an image forming apparatus according to an embodiment of the present invention.

  An image forming apparatus 1 according to an embodiment of the present invention includes a motor drive device according to an embodiment of the present invention, and has a plurality of functions such as a copy function, a printer function, a scanner function, and a facsimile function. It is a multifunction machine. The image forming apparatus 1 includes an apparatus main body 11 that includes an operation unit 47, an image forming unit 12, a fixing unit 13, a paper feeding unit 14, a document feeding unit 6, a document reading unit 5, and the like.

  The operation unit 47 receives instructions such as an image forming operation execution instruction and a document reading operation execution instruction from the operator regarding various operations and processes that can be executed by the image forming apparatus 1.

  When the image forming apparatus 1 performs a document reading operation, the document reading unit 5 optically reads a document fed by the document feeding unit 6 or a document placed on the document placing glass 161, Generate image data. Image data generated by the document reading unit 5 is stored in a built-in HDD or a network-connected computer.

  When the image forming apparatus 1 performs an image forming operation, it is based on image data generated by the document reading operation, image data received from a computer connected to a network, image data stored in a built-in HDD, or the like. Then, the image forming unit 12 forms a toner image on the recording paper P as a recording medium fed from the paper feeding unit 14. When performing color printing, the magenta image forming unit 12M, the cyan image forming unit 12C, the yellow image forming unit 12Y, and the black image forming unit 12Bk of the image forming unit 12 respectively A toner image is formed on the photosensitive drum 121 by charging, exposure, and development processes based on an image composed of each color component constituting data, and the toner image is formed on the intermediate transfer belt 125 by the primary transfer roller 126. Let them transcribe. The magenta image forming unit 12M, the cyan image forming unit 12C, the yellow image forming unit 12Y, and the black image forming unit 12Bk of the image forming unit 12 each have a corresponding color toner. .

  The toner images of the respective colors transferred onto the intermediate transfer belt 125 are superimposed on the intermediate transfer belt 125 with the transfer timing adjusted to form a color toner image. The secondary transfer roller 210 passes the toner image of the color formed on the surface of the intermediate transfer belt 125 from the paper supply unit 14 through the conveyance path 190 at a nip N between the intermediate transfer belt 125 and the driving roller 125a. It is transferred to the recording paper P that has been conveyed. Thereafter, the fixing unit 13 fixes the toner image on the recording paper P to the recording paper P by thermocompression bonding. The recording paper P on which the color image has been formed after completion of the fixing process is discharged to a discharge tray 151.

  In the case of performing double-sided printing in the image forming apparatus 1, the recording paper P having an image formed on one side by the image forming unit 12 is nipped by the discharge roller pair 159, and then the recording paper P is switched back by the discharge roller pair 159 and sent to the reverse conveyance path 195, and the conveyance roller pair 19 conveys the recording paper P again upstream in the conveyance direction of the recording paper P with respect to the nip portion N and the fixing unit 13. As a result, an image is formed on the other surface of the recording paper by the image forming unit 12.

  The toner of each color is supplied from a toner container 127 (toner supply unit) provided for each image forming unit of each color to the developing device of the image forming unit. In FIG. 1, only the toner container 127 provided in the image forming unit 12M is shown in order to avoid the complication of FIG. Each toner container includes an agitating mechanism 1271 for agitating the toner and a toner replenishing roller 1272. For example, the stirring mechanism includes a rotation shaft instructed to rotate freely in the toner container and fins attached thereto, and the rotation shaft is directly or indirectly set by the toner motor 80 (FIG. 2) mounted on the image forming apparatus 1. The toner in the toner container 127 is agitated by being driven to rotate. The toner supply roller 1272 provided in the toner container 127 is rotationally driven by the rotational driving force supplied from the toner motor 80.

  Next, the configuration of the image forming apparatus 1 will be described. FIG. 2 is a functional block diagram showing the main internal configuration of the image forming apparatus 1.

  The image forming apparatus 1 includes a control unit 10. The control unit 10 includes a CPU (Central Processing Unit), a RAM, a ROM, a dedicated hardware circuit, and the like, and controls overall operation of the image forming apparatus 1.

  The document reading unit 5 includes the reading mechanism 163 having a light irradiation unit, a CCD sensor, and the like under the control of the control unit 10. The document reading unit 5 reads an image from the document by irradiating the document with the light irradiating unit and receiving the reflected light with a CCD sensor.

  The image processing unit 31 performs image processing on the image data of the image read by the document reading unit 5 as necessary. For example, the image processing unit 31 performs predetermined image processing such as shading correction in order to improve the quality after the image read by the document reading unit 5 is formed by the image forming unit 12.

  The image memory 32 is an area for temporarily storing document image data obtained by reading by the document reading unit 5 and temporarily storing data to be printed by the image forming unit 12.

  The image forming unit 12 forms an image such as print data read by the document reading unit 5 and print data received from the computer 200 connected to the network.

  The operation unit 47 receives instructions from the operator regarding various operations and processes that can be executed by the image forming apparatus 1. The operation unit 47 includes a display unit 473.

  The facsimile communication unit 71 includes an unillustrated encoding / decoding unit, modulation / demodulation unit, and NCU (Network Control Unit), and performs facsimile transmission using a public telephone network.

  The network interface unit 91 includes a communication module such as a LAN board, and transmits and receives various data to and from the computer 200 on the Internet or in a local area.

  The HDD 92 is a large-capacity storage device that stores document images and the like read by the document reading unit 5.

  For example, a thermistor or the like is used as the environmental temperature sensor 60 and detects the ambient temperature (environment temperature) of the image forming apparatus 1. The environmental temperature sensor 60 detects an environmental temperature of a predetermined low temperature (for example, a temperature of 10 ° C. or less). The environmental temperature sensor 60 is installed at an appropriate position outside or inside the image forming apparatus 1.

  The driving motor 70 is a driving source that applies a rotational driving force to each rotating member of the image forming unit 12, the conveyance roller pair 19, and the like.

  As described above, the toner motor (an example of a motor) 80 is mainly a motor for agitating the fresh toner stored in the toner container. In the present embodiment, a DC brush motor is used as the toner motor 80.

  The control unit 10 includes a control unit 100 and a motor control unit 101.

  The control unit 100 includes a document reading unit 5, a document feeding unit 6, an image processing unit 31, an image memory 32, an image forming unit 12, an operation unit 47, a facsimile communication unit 71, a network interface unit 91, and an HDD (hard disk drive) 92. Etc., and drive control of these parts is performed.

  The motor control unit 101 drives and controls the toner motor 80. The motor control unit 101 controls whether the DC current is supplied to the toner motor 80 by controlling on / off of the switch element 82 (FIG. 3).

  Next, a control system for the toner motor 80 will be described. FIG. 3 is a schematic circuit diagram showing a control system of the toner motor 80.

  The DC power supply 81 is a power supply that supplies a DC current to the toner motor. A switch element 82 is connected between the DC power supply 81 and the toner motor 80. The switch element 82 is composed of a transistor such as a bipolar or FET (Field Effect Transistor). A resistor 83 is connected to the toner motor 80 in series. The resistor 83 is a current detection resistor that detects a current flowing through the toner motor 80, and the motor current is represented by a voltage Vs between the toner motor 80 and the resistor 83.

  The comparator 84 compares the voltage Vs of the resistor 83 with the reference voltage V1. As will be described later, the reference voltage V1 is a predetermined voltage representing a continuous energization start current for determining that the toner motor 80 is switched from intermittent driving to continuous driving. The output C1 of the comparator 84 is supplied to the motor control unit 101.

  The comparator 85 compares the voltage Vs of the resistor 83 with the reference voltage V2. As will be described later, the reference voltage V2 is a voltage representing a predetermined abnormality detection current for detecting a start failure of the toner motor 80. The output C2 of the comparator 85 is supplied to the motor control unit 101. The value of the abnormality detection current is determined in advance by selecting an appropriate value by the manufacturer or the like according to the performance of the toner motor 80, the drive current value, and the like.

  The motor control unit 101 drives the toner motor 80 by energizing the toner motor 80 with a DC current from the DC power supply 81 by turning on the switch element 82. When the switch control signal ctl output from the motor control unit 101 is at a high level, the switch element 82 is turned on, and when the switch control signal ctl is at a low level, the switch element 82 is turned off. The motor control unit 101 receives the temperature detection signal T from the environmental temperature sensor 60, and the environmental temperature of the image forming apparatus 1 indicated by the temperature detection signal T is a predetermined normal temperature (temperature exceeding 10 ° C.). If so, the toner motor 80 is continuously driven by always turning on the switch element 82. As a result, the current flowing through the toner motor 80 settles to a predetermined current with a curve as shown in FIG.

  On the other hand, the motor control unit 101 detects that the environmental temperature sensor 60 is equal to or lower than the predetermined low temperature, and is a predetermined time (for example, 10 minutes) from the previous driving stop of the toner motor 80. When the toner has elapsed, the toner motor 80 is intermittently driven by repeating energization for a drive time shorter than the electrical time constant of the toner motor 80. Thereby, when it is assumed that the load of the toner motor 80 is large under a low temperature environment, the driving of the toner motor 80 can be started so that no overcurrent flows through the toner motor 80 and the switch element 82.

  Furthermore, when the maximum drive current of the toner motor 80 in each drive of the toner motor 80 falls below the continuous energization start current, the motor control unit 101 repeats energization for a drive time shorter than the electrical time constant. Switching from intermittent driving of the toner motor 80 to continuous driving by continuous energization is performed. FIG. 4 is a graph showing temporal changes in the switch control signal ctl output from the motor control unit 101 and the drive current when the toner motor 80 is normal. As shown in the figure, the motor control unit 101 outputs the switch control signal ctl by a rectangular wave having a high level and a low level in a low temperature environment. However, the high level period of the switch control signal ctl is set to be shorter than the electrical time constant Te of the toner motor 80. The low level period of the switch control signal ctl is set to a predetermined time, for example, a time equal to the high level period. The motor control unit 101 evaluates the logic level of the output C1 of the comparator 84 every time the toner motor 80 is driven, and for example, the maximum of the toner motor 80 during one cycle of the switch control signal ctl as a rectangular wave. If it is determined that the drive current is kept below the continuous energization start current, the switch control signal ctl is fixed at a high level, the switch element 82 is always turned on, and the drive system of the toner motor 80 is switched to continuous drive. .

  As a result, the driving of the toner motor 80 is started so that an overcurrent does not flow through the toner motor 80 and the switch element 82 in a low temperature environment where the load on the toner motor 80 is assumed to be large. When it can be determined that there is no risk of overcurrent flowing in the battery, it is possible to smoothly switch to normal continuous energization.

  Further, the motor control unit 101 determines in advance that the maximum drive current of the toner motor 80 in each drive of the toner motor 80 exceeds the abnormality detection current at least once during one cycle of the switch control signal ctl. When the error detection time Terr (for example, 4 seconds) has continued, the activation error is determined. FIG. 5 is a graph showing the change over time of the switch control signal ctl output from the motor control unit 101 and the start-up current when the start-up failure of the toner motor 80 occurs. As shown in the figure, the motor control unit 101 outputs a switch control signal ctl in a rectangular wave shape under a low temperature environment. The motor control unit 101 evaluates the logic level of the output C2 of the comparator 85 every time the toner motor 80 is driven, and the above-described state in which the maximum drive current of the toner motor 80 exceeds the abnormality detection current is detected as an error. If it is determined that the toner has continued for the time Terr or more, it is determined that the toner motor 80 has failed to start. When the motor control unit 101 determines that the toner motor 80 has failed to start, for example, the switch control signal ctl is fixed at a low level and the switch element 82 is always turned off, and overcurrent continues to flow through the toner motor 80 and the switch element 82. Avoid the situation.

  As a result, in a low temperature environment where the load on the toner motor 80 is assumed to be large, the toner motor 80 starts to be driven while preventing the overcurrent from flowing through the toner motor 80 and the switch element 82. When it is determined that there is a possibility that the toner flows, it is possible to detect a start failure of the toner motor 80 and take measures such as forcibly stopping the driving of the toner motor 80, for example.

  The motor driving device according to an embodiment of the present invention includes at least an environmental temperature sensor 60, a toner motor 80, and a motor control unit 101.

  Next, an embodiment of driving the toner motor 80 by the motor control unit 101 will be described. FIG. 6 is a flowchart illustrating an embodiment of toner motor driving by the motor control unit 101.

  First, the motor control unit 101 determines whether or not the environmental temperature is the predetermined low temperature based on the temperature detection signal T given from the environmental temperature sensor 60 (S1). When the motor control unit 101 determines that the environmental temperature is not the low temperature (NO in S1), the switch control signal ctl is fixed to a high level, the toner motor 80 is continuously energized, and the toner motor 80 is continuously supplied. The driving is started (S2).

  On the other hand, when the motor control unit 101 determines that the environmental temperature is the low temperature (YES in S1), the motor control unit 101 determines an elapsed time from the end of the previous driving of the toner motor 80 (S3). When the motor control unit 101 determines that the predetermined time has not elapsed since the end of the previous driving of the toner motor 80 (NO in S3), the motor control unit 101 starts driving the toner motor 80 continuously (NO in S3). S2).

  On the other hand, when the motor control unit 101 determines that the predetermined time has elapsed since the previous driving of the toner motor 80 has ended (YES in S3), the motor control unit 101 starts intermittent driving of the toner motor 80 described above (S4). ). That is, the motor control unit 101 controls the switch element 82 on / off by setting the high level period of the switch control signal ctl shorter than the electrical time constant of the toner motor 80.

  During intermittent driving of the toner motor 80, the motor control unit 101 keeps the maximum drive current of the toner motor 80 below the continuous energization start current for one cycle of the switch control signal ctl as a rectangular wave. If it is determined that the toner motor 80 is in a continuous state (YES in S5), the toner motor 80 is continuously driven assuming that continuous energization is possible (S2).

  On the other hand, during the intermittent driving of the toner motor 80, the motor control unit 101 determines that the maximum drive current of the toner motor 80 does not fall below the continuous energization start current (NO in S5), and the toner motor in each drive of the toner motor 80. When it is detected that the maximum drive current of 80 continues to exceed the abnormality detection current at least once during one cycle of the switch control signal ctl, and this state continues for the error detection time Terr (YES in S6) Then, it is determined that the toner motor 80 has failed to start (error detection) (S7). When detecting an error, the motor control unit 101 forcibly stops the driving of the toner motor 80 as described above, for example. On the other hand, when the motor control unit 101 determines that the above-described state in which the maximum drive current of the toner motor 80 exceeds the abnormality detection current has not continued for the error detection time Terr (NO in S6), the process returns to S5 and returns to the toner motor 80. It is determined whether the maximum drive current of the current has fallen below the continuous energization start current.

  As described above, according to this embodiment, when it is assumed that the load of the toner motor 80 is large under a low temperature environment, the toner motor 80 is driven so that no overcurrent flows through the toner motor 80 and the switch element 82. Can start. Further, when it can be determined that there is no possibility that an overcurrent flows through the toner motor 80, it is smoothly switched to normal continuous energization, and when it is determined that there is a possibility that an overcurrent flows through the toner motor 80, the toner Measures such as forcibly stopping the driving of the motor 80 can be taken.

  FIG. 7 is a graph showing a temporal change in the starting current when the toner motor is normal when the motor drive control according to the present embodiment is not used. In the case where the motor drive control according to the present embodiment is not used, when the driving of the toner motor is started, the starting current increases exceeding the electrical time constant Te (inrush current), and then the toner motor rotor starts to rotate. The current decreases and converges to a predetermined current. That is, at normal times, the toner motor is continuously driven with the switching elements such as transistors always turned on, so that the starting current of the toner motor draws a curve as shown in FIG. 7 and settles to a predetermined current.

  On the other hand, FIG. 8 is a graph showing a temporal change of the starting current when the toner motor starts up poorly when not using the motor drive control according to the present embodiment. If the motor drive control according to the present embodiment is not used, the toner motor may start up poorly due to an increase in the load in a low temperature environment or the like, or the start-up current may increase (the inrush current may continue). is there. At the time of start-up failure, as shown in FIG. 8, even if an inrush current occurs, the current may not continue to decrease and may continue as it is. In this case, there is a risk that the overcurrent continues to flow through the toner motor and the control device for a long time, causing damage. For this reason, when the motor drive control according to the present embodiment is not used, if the overcurrent state continues for a predetermined error detection time or longer when the toner motor is started, a start error is detected, for example, the toner motor is driven. Error processing such as forced stop is performed. In this case, it is necessary to use an overspec control device rather than the original specification, which causes an increase in cost.

  However, according to the embodiment of the present invention described above, the toner motor 80 and the switch element 82 can be effectively prevented from overcurrent without using an overspec control device for driving the toner motor 80 in the image forming apparatus 1. Since it can protect, unnecessary cost increase can be suppressed. In addition, it is possible to provide a margin for the detection time of the start-up failure of the toner motor 80, and the optimal timing design is facilitated, and the convenience for the user can be improved.

  The present invention is not limited to the configuration of the above embodiment, and various modifications can be made. For example, in the above-described embodiment, the image forming apparatus according to an embodiment of the present invention has been described using a multifunction peripheral. However, this is merely an example, and other electronic devices such as a printer, a copier, a facsimile machine, and the like. Another image forming apparatus such as an apparatus may be used.

  In addition, the motor driving device according to the embodiment of the present invention is not limited to that provided in the image forming apparatus 1, and may be provided in an electronic device.

  Moreover, in the said embodiment, the structure and process which were shown by the said embodiment using FIG. 1 thru | or FIG. 6 are only one Embodiment of this invention, and are not the meaning which limits this invention to the said structure and process.

1 Image forming apparatus 60 Environmental temperature sensor 80 Toner motor 101 Motor controller

Claims (3)

An environmental temperature sensor for detecting the environmental temperature;
A motor for supplying driving force to the driven object;
A motor control unit for controlling the drive of the motor,
The motor controller is
When the environmental temperature sensor detects a temperature equal to or lower than a predetermined temperature at the start of driving the motor, and a predetermined time has elapsed since the previous driving stop of the motor, By energizing with a driving time shorter than the electrical time constant of the motor, the motor is intermittently driven ,
When the maximum driving current of the motor at each driving time of the motor is lower than a predetermined first current value, switching energization with a driving time shorter than the electrical time constant to continuous energization, A motor driving device for driving the motor. The motor control unit determines a start error when a state in which the maximum driving current of the motor at each driving time of the motor exceeds a predetermined second current value continues for a predetermined time or longer. The motor driving device according to claim 1 . The motor driving device according to claim 1 or 2 ,
An image forming unit for forming an image on a recording medium;
A toner supply unit for supplying toner to the image forming unit,
The motor is an image forming apparatus that supplies a driving force to a toner stirring mechanism or a toner replenishing roller of the toner supply unit.

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