JP2006330506A - Image forming apparatus and abnormal spot specifying method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inexpensively obtain constitution for detecting the abnormality of an image forming apparatus. <P>SOLUTION: A current detection circuit 502 is provided in each functional unit. A control unit reads out a standard consumed current value in the functional unit in every predetermined timing from a storage part and obtains the consumed current value flowing to the unit from a current detection circuit 502 so as to compare the current values. As a result, when a difference equal to or above a predetermined value is found between the current values, it is detected as the abnormality of the object unit. Furthermore, a control means for performing the specified control of abnormal load to specify the abnormal load in order to specify the load is provided to specify what load in what unit is abnormal. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a copying machine or a printer, and also relates to an abnormality detection method for an electronic apparatus such as an image forming apparatus.

  Conventionally, as a method for detecting an abnormality, there is a method in which an abnormality detection circuit is provided for each load, and when an abnormality occurs, an abnormality detection signal for notifying the controller of the abnormality is output. When the abnormality detection signal is input to the control unit, it detects that an abnormality has occurred in the load, performs abnormality control according to the location where the abnormality has occurred, and displays the occurrence of the abnormality on the display unit. Alternatively, a cutoff circuit that protects against overcurrent is provided in each load, and when an abnormality occurs in which overcurrent occurs, the cutoff circuit is activated to protect the device, and a display requesting a service call is performed on the display unit.

  When an abnormality detection circuit is used, a control means for controlling the image forming apparatus itself with an abnormality detection signal indicating that the load, for example, the motor itself detects abnormally high-speed rotation, abnormal low-speed rotation, or locked state of the motor and is abnormal Output to. The control means that has detected the abnormality stops the image forming operation. Further, after energization of the motor in which an abnormality has occurred is stopped and safety is ensured, the display unit displays and notifies that an abnormality has occurred. Alternatively, when connected to an external device such as a personal computer, the control means notifies the external display screen through the communication means by displaying that an abnormality has occurred in the image forming apparatus ( (See Patent Document 1).

On the other hand, for example, when an abnormality occurs in a load such as a motor, there is a method of dealing with an overcurrent flowing through the load due to the occurrence of an abnormality using a cutoff circuit provided in the motor. When using a breaker circuit, for example, a fuse or the like is used to shut off the overcurrent flowing to the motor, thereby avoiding a danger caused by an abnormal temperature rise caused by the overcurrent and obtaining safety.
Japanese Patent Laid-Open No. 9-327949 (page 7, FIG. 1)

  However, in the prior art, in order to detect an abnormality in the load, it is necessary to provide an abnormality detection circuit or a cut-off circuit in each of the load itself and a control unit that drives and controls the load. For this reason, there is a problem that the cost of the apparatus is increased by adding an additional circuit that performs a function other than the original function of the load to the load itself or the load control unit for the abnormality detection circuit or the cutoff circuit. .

  In addition, a simple interruption circuit such as a fuse may cost less, but when the interruption circuit functions, it has not been possible to immediately identify in which load an abnormality has occurred. In particular, when a device in which an abnormality has occurred from an external device such as a computer is used, even the fact that the device has failed may not be known from the external device.

  The present invention has been made in view of the above conventional example, and can detect the occurrence of an abnormality with a simple configuration, identify the location where the abnormality has occurred, and output the occurrence of the abnormality and the portion to the outside. An object of the present invention is to provide a forming apparatus and an abnormal part detection method.

  In order to achieve the above object, the present invention comprises the following arrangement.

An image forming apparatus,
A plurality of functional units that are divided into functions of the image forming apparatus and that include a current measuring unit that measures a current consumption value and an output unit that outputs the measured current consumption value;
For each of the plurality of functional units, storage means for storing in advance a unit standard value which is a standard of current consumption at a predetermined timing of an operation sequence of function execution;
The current consumption value at the predetermined timing is received from the target functional unit identified from among the plurality of functional units, and compared with the standard value at the corresponding timing stored in the storage means, and a difference greater than or equal to the predetermined value When there is, there is a control means for judging that an abnormality has occurred and outputting information indicating that the functional unit has an abnormality to the outside.

More preferably, the storage means further stores, for each of the plurality of functional units, a load standard value that is a standard of current consumption for each load belonging to the functional unit,
When it is determined that an abnormality has occurred in the target functional unit, the control unit sequentially drives the load belonging to the target unit, compares it with the load standard value, and when there is a difference of a predetermined value or more. Is characterized by judging that an abnormality has occurred and outputting information indicating that the load has an abnormality to the outside.

Alternatively, a plurality of units that control or drive a plurality of loads and execute a function classified for each function of the image forming apparatus are communicated with a control unit that controls the plurality of units. An image forming apparatus that performs an image forming operation by controlling a unit,
Each unit includes a current detection means for detecting current consumption consumed by the unit, a control unit and a communication means, controls the unit itself, communicates information obtained by the unit to the control unit, and performs control. The load is controlled by the communication command from the unit,
In the control unit, from each storage unit storing a standard current consumption value consumed by each unit at each timing when driving of the load is changed by executing an image forming operation in each unit, from the storage unit to the storage unit At the timing corresponding to the stored standard consumption current value, the consumption current value detected by the current detection unit is received from each unit, the current value is compared with the standard consumption current value read from the storage unit, When the comparison result detects a difference of a predetermined value or more, it outputs that an abnormality has occurred.

Alternatively, a plurality of functional units that are classified by function and include a current measuring unit that measures a current consumption value, and an output unit that outputs the measured current consumption value,
For each of the plurality of functional units, an electronic apparatus comprising storage means for storing in advance a unit standard value that is a standard of current consumption at a predetermined timing of an operation sequence for performing functions,
Receiving a current consumption value at the predetermined timing from a target functional unit identified from the plurality of functional units;
A comparison step for comparing with a standard value at a corresponding timing stored in the storage means;
If there is a difference greater than or equal to a predetermined value as a result of the comparison, the abnormality location is characterized by comprising an output step of determining that an abnormality has occurred and outputting information indicating that the function unit has an abnormality to the outside Identification method.

Alternatively, a plurality of functional units that are classified by function, and that include a current measuring unit that measures a consumption current value and an output unit that outputs the measured consumption current value;
For each of the plurality of functional units, storage means for storing in advance a unit standard value which is a standard of current consumption at a predetermined timing of an operation sequence of function execution;
The current consumption value at the predetermined timing is received from the target functional unit identified from among the plurality of functional units, and compared with the standard value at the corresponding timing stored in the storage means, and a difference greater than or equal to the predetermined value An electronic device capable of detecting an abnormality on a functional unit basis, comprising a control means for determining that an abnormality has occurred and outputting information indicating that the functional unit has an abnormality to the outside. apparatus.

  According to the present invention, when an abnormality occurs in the apparatus, it is possible to identify a load in which an abnormality has occurred even if each load is not provided with an abnormality detection circuit or the like. Furthermore, the result of abnormality detection, that is, the fact that the abnormality has occurred and the location where the abnormality has occurred can be output to the outside and notified.

<Outline of the Invention>
The outline of the present invention is as follows. That is, a current detection circuit (digital ammeter) is provided for each unit that controls each part of the image forming apparatus. By providing a current detection circuit in each unit, current detection can be performed in units. The normal current value (standard value) of the unit is stored in advance in the storage means at every fixed operation timing during the image forming operation. As information stored in the storage means, standard values at normal time consumed by all units in the apparatus are required. Next, the current value (actually measured value) measured by the current detection circuit provided in each unit is received by the control circuit and compared with the standard value stored in the storage means. When a load abnormality occurs, an abnormally large current flows compared to the standard time, or only a small current flows. Can be judged. By performing this control for all units, it is determined which unit is normal and abnormal. By performing the above control, it can be determined whether or not an abnormality has occurred in the unit.

  Further, a standard value of current consumption for each load provided in each unit is stored in the storage means. And while driving each load, the measured value of the consumption current of each unit is received by the control unit, and the standard value and the measured value are compared. As a result of the comparison, if the difference between the standard value and the actual measurement value is larger than a certain value, it can be determined that there is an abnormality in the load being driven at that time.

  In this way, the occurrence of an abnormality, the unit in which the abnormality has occurred, and the load in which an abnormality has occurred can be identified.

[First Embodiment]
<Configuration of image forming apparatus>
FIG. 2 is a block diagram of an image forming apparatus configured to perform communication between units via a power line. The arrow from each unit to each load indicates the direction in which the command or status is transmitted. If there is an output-only load, there is also a load that transmits in both input and output directions.

  The control unit 201 is a control unit that transmits commands to the units 202 to 206 in order to control the image forming apparatus and realize an image forming operation. The units 202 to 206 other than the control unit are referred to as functional units. The control unit 201 instructs each other unit to drive a load connected to the communication partner unit at a timing specified through communication (issues a command). Receiving this instruction, each of the units 202 to 206 belongs to the unit in a sequence corresponding to the instruction (that is, under the control of the control unit of the unit), loads 2021 to 2026, 2031 to 2033, 2041 to 2043, 2051. Drive control of 2053 and 2061 to 2063 is performed. That is, the control unit 201 controls the units 202 to 206 through the above-described communication, thereby driving the loads (for example, a motor, a solenoid, a heater, etc.) of each unit to realize an image forming operation.

  Communication between the control unit 201 and each of the units 202 to 206 communicates with two power supply lines of Vcc (power supply potential) and GND (ground potential) connected to the control unit 201 and each of the units 202 to 206. This is done by modulating and superimposing the signal. The control unit 201 and each of the units 202 to 206 also include a communication circuit that modulates and superimposes data such as commands and responses on the power supply line and separates and demodulates the signal from the power supply line.

  At the time of communication, the control unit 201 selects only one communication partner unit to communicate with the communication signal superimposed on the power line, and then communicates with the selected unit. That is, the control unit 201 polls the communication partner units in order and communicates with the selected partner. Polling may be performed by a selection command. However, a selection command may not be provided, and a configuration in which information specifying a counterpart unit is included in a normal command may be used.

  All units that communicate with the control unit 201 are also provided with a control unit for controlling the communication circuit and the unit itself.

  The control unit of each unit controls the load connected to the unit in accordance with the instruction content received from the control unit 201. In addition, the control unit of each unit collects information such as a current consumption value by a current measurement circuit that measures a current value flowing through the unit and a sensor necessary for an image forming operation such as paper detection, and stores the information. It plays a role of controlling the communication circuit in order to transmit / receive data to / from.

  The role of each unit and load will be briefly described below with reference to FIG. The unit 202 is a unit that performs paper conveyance and driving, and is responsible for paper conveyance in the range from paper feeding to the photosensitive drum and driving of the main motor M1 (2021). The main motor M1 is a drive source that conveys the paper from the paper feed to the discharge port and rotationally drives the photosensitive drum. The paper feed solenoid SL1 (2022) is used to drive a paper feed roller for feeding paper in the cassette. The registration clutch CL1 (2023) is a clutch that aligns the fed paper and the toner image in the paper conveyance direction (sub-scanning direction) from the front edge of the paper. The paper remaining detection sensor 2024 is for detecting whether or not there is paper in the cassette. The paper feed sensor 2025 and the registration sensor 2026 check whether the paper is jammed in the paper transport path. It is a sensor for detecting. These are composed of known mechanical mechanisms and photosensors.

  The unit 203 forms an electrostatic latent image on the photosensitive drum from laser light irradiation according to an image signal and high-voltage charging, and applies a developing bias for placing the toner on the electrostatic latent image. Create an image. Further, the high-pressure unit is used for transferring the toner image onto a sheet and transferring the image onto the sheet. For this purpose, a primary charger 2031, a developing charger 2032, and a transfer charger 2033 (charging roller 34) are provided as loads.

  The unit 204 has an external interface 2042 for inputting an external print request and an image signal into the apparatus. Here, the state of the apparatus can be notified to a personal computer or the like. In this embodiment, a USB terminal is provided as an external interface. In addition, there is an operation unit 2043 including a key input unit for inputting to the image forming apparatus and a display unit for displaying the state of the image forming apparatus. Further, the rotary polygon mirror is driven to rotate at a predetermined speed by the laser scanner motor 2041. Further, the laser light is turned on / off by converting the image signal into, for example, a PWM modulation signal synchronized with the rotation period of the rotary polygon mirror. The laser beam is irradiated onto the rotating polygon mirror and the reflected light is irradiated onto the photosensitive drum. At the same time, an electrostatic latent image is formed on the photosensitive drum by using the high voltage of the high voltage unit 203, and a toner image is formed from the latent image. A desired image is created by transferring the toner image to the created paper.

  The unit 205 is a unit for carrying the paper from before fixing to discharging, and carries out the paper conveyance by the paper discharge clutch 2053, and detects a paper jam in the paper conveyance path by the pre-fixing sensor 2052 and the paper discharge sensor 2051. As described in the unit 202, the sensor includes a known mechanical mechanism and a photosensor. The sheet on which the toner image has been transferred is separated from the photosensitive drum by the separation charger 2034, and the sheet is conveyed to the fixing unit 206. The fixing unit 206 fixes the unfixed toner image on the paper, and then discharges the toner image outside the apparatus.

  A unit 206 is a fixing unit. The unit 206 for controlling the fixing system controls the fixing heater 2062 based on the information of the fixing thermistor 2061, and plays a role of fixing the toner image transferred onto the sheet to the sheet while keeping the temperature of the fixing roller at a predetermined high temperature. Yes. The exhaust heat fan 2063 prevents the temperature inside the apparatus from being raised due to the influence of the heater 2062, and exhausts substances generated when high pressure is applied, such as generated ozone, to the outside through the filter.

  However, the power consumption of the fixing heater 206 is as high as several hundred watts at the minimum. For this reason, a voltage source of a commercial power source is used for the fixing heater, and the applied voltage is controlled by phase control, wave number control, or the like. Therefore, power lines of commercial voltage power (AC power supply) other than the Vcc and GND lines are supplied to the unit 206. The communication signal described above is not superimposed on the AC power line used here.

  Also, the fixing system abnormality is performed by the control unit of the unit 206 (described later with reference to FIG. 3). The temperature is detected by using a thermistor 2061 provided so as to be in contact with the fixing roller 36 for thermally fixing the unfixed image. The temperature information is obtained by connecting the thermistor 2061 and a resistor in series and changing the resistance value of the thermistor depending on the temperature, and converting the divided thermistor voltage into temperature information using a temperature conversion table based on the voltage value. Using the converted temperature information, the fixing temperature is monitored to detect a temperature abnormality.

  When a user executes a print output command from a personal computer or the like (not shown), an image is generated in the image forming mode of the print set mode from the external interface (USB terminal in the embodiment) of the unit 4 connected to the personal computer. Perform formation.

<Control unit of each functional unit>
FIG. 3 shows a block diagram of main components inside the functional units 202 to 206. In FIG. 3, the control unit 501 includes a communication circuit 5011 and a control circuit 5012, and controls the unit itself. In addition, a load 503 corresponding to the function performed by each functional unit is connected to the functional unit. The power supply power is supplied to each of the control unit 501, the current detection circuit 502, and the load 503. Further, the communication circuit 5011 modulates and superimposes a signal on the power line (Vcc), and separates and demodulates the signal.

  The control unit 501 not only controls the unit but also communicates with the control unit 201 using the communication circuit 5011. This communication is performed with the control unit of the control unit 201 via a communication circuit provided in the control unit 201. The control unit 501 controls the load of the unit based on the information (instructions and data) received from the control unit 201, and transmits the current consumption value and the sensor state in the unit to the control unit 201.

  The current detection circuit 502 measures the power consumption value by each of the functional units 202 to 206 and inputs it to the control circuit 5012 as a digital value. The voltage applied to the unit is a potential difference between Vcc and GND. However, the ground level to the load system in the unit is set to the potential of GND1 in FIG. Therefore, the current that flows between GND1 and GND is the total current that flows in the unit. In order to detect the current, a low resistance R1 (5021) is inserted between GND1 and GND, and the voltage generated by the resistance R1 is converted into a digital value by the A / D converter 5022. The output value of the AD converter 5022 is a value indicating the current value consumed in the unit. However, the current value itself is not limited to the ampere unit, and the measured value is converted by the control circuit 5012 in consideration of constants such as a resistance value and a quantization step (reference voltage) in order to obtain a ampere unit value. Sometimes it is necessary. The reference voltage for A / D conversion is the voltage Va, which is a value obtained by changing the power supply voltage Vcc so that Vcc> Va in order to accurately read the potential difference between both ends of the resistor R1. The voltage Va stabilized from the voltage of Vcc is created using a known three-terminal regulator or the like. In the embodiment, Va is used as the power supply voltage of the logic units of the communication circuit 5011 and the control circuit 5012 and the power supply voltage to the current detection circuit 5012.

  The transistor Q1 (5023) placed in parallel with the resistor R1 is connected between GND and GND1 in order to prevent the influence of the resistor R1 when a large current flows through the load 503, that is, the rise of the ground potential GND1 due to an increase in voltage drop. It is provided to play the role of maintaining the potential at the collector-emitter voltage of the transistor Q1. If the transistor Q1 is made conductive, the current flows through the transistor Q1, so that a back electromotive voltage (R1 × current) due to the resistor R1 can be prevented. The base (or gate) signal of the transistor Q1 is controlled by the control circuit 5012.

  For example, the starting current when starting the main motor M1 needs to flow a larger current than the normal time. This is because if the resistor R1 is inserted, the start-up current becomes small and the start-up time of the main motor M1 may become long, and if the start-up time of the main motor M1 becomes long, the image forming operation may be affected. In order to prevent this influence, by turning on the transistor Q1 when the main motor M1 is started, a route that allows a large current equivalent to the start current to flow is provided, and the start-up time of the main motor M1 becomes longer due to a decrease in the start-up current due to the resistor R1. This prevents the effects of

  Note that when the transistor Q1 is on (conducting), the current flowing through the resistor R1 cannot be measured. Therefore, in this embodiment, the current measurement is not performed while the transistor Q1 is on. Alternatively, the measured current value is not used. It is obvious that the same effect can be obtained by replacing the transistor Q1 with another semiconductor such as an FET or a switching element such as a relay.

<Image forming operation>
FIG. 4 is a cross-sectional view of an image forming apparatus using the laser scanner of the embodiment. The outline of the image forming operation will be described below with reference to FIGS.

  When the apparatus main body is turned on, the unit 201 transmits a command to prepare for performing an image forming operation by communication to the functional units 202 to 206. This state during the preparation period is called wait-up. During the wait-up, a USB terminal (not shown) provided in the unit 204 is notified that the apparatus is waiting up, and the print command is not accepted. As a means for notifying the outside of the apparatus alone, the fact that the apparatus is waiting is displayed on a display unit (not shown) for displaying the state of the apparatus.

  Next, the unit 201 performs communication for transmitting an instruction to the unit 206 to raise the temperature of the unfixed toner image to a temperature at which the unfixed toner image can be fixed to the sheet by communication via the power line. The communication is received by the unit 206, and the unit 206 controls as follows.

  The fixing heater 2062 is driven by an AC power source from the fixing temperature information from the thermistor 2061 in contact with the fixing roller 36 to apply heat, thereby fixing the fixing nip portion of the fixing roller 36 (paper and an unfixed toner image on the paper). The temperature is raised to a temperature at which the image can be fixed by a pressurizing unit that is fixed by applying pressure and heat. During the control, the unit 201 drives the main motor M1 (2021) of the unit 202 when the temperature reaches a predetermined temperature or higher from the temperature information of the thermistor 2061. Further, the unit 203 is used to initialize the photosensitive drum (primary charging or the like) so that an image forming operation can be executed. After these series of preparation operations are completed, a print command is accepted. This state is called a standby state. The description after the standby state will be described below.

  The unit 201 detects through communication with the unit 204 that a print command has been input from a USB terminal which is an external interface 2042 provided in the unit 204 connected to a personal computer or the like. Then, in order to perform an image forming operation, the unit 201 controls each unit as follows using communication via the power line.

  After driving the main motor M1 used as a driving source for the photosensitive drum 35 and paper conveyance, at least a predetermined time for the main motor M1 to stably rotate, the sheet feeding solenoid SL1 is turned on. As a result, the stop mechanism of the half-moon roller 31 serving as a paper feed roller is released and rotates in the direction of arrow B, so that the half-moon roller 31 feeds the paper P set in the paper feed cassette.

  The paper P is fed from the paper feed cassette by rotating the half moon roller 31. When the stop mechanism is operated, by turning off the paper feed solenoid SL1 before the half-moon roller 31 rotates once, the half-moon roller 31 hits the stopper mechanism after one rotation, and the rotation of the paper feed roller 31 can be stopped.

  Even if the main motor M1 is rotating, when the sheet feeding solenoid SL1 is not driven, a sheet feeding control is performed by providing a known mechanical mechanism that stops the rotation by the stop mechanism so as not to rotate the half-moon roller 31. Yes. This stop mechanism can be stopped even if the main motor M1 is not driven and the feed solenoid SL1 is erroneously turned on / off once to remove the stop mechanism, or the main motor M1 is driven from that state. The mechanism is held, and the half-moon roller 31 is structured not to rotate.

  Further, a clutch can be used as a paper feed mechanism. In the case of a clutch, a round roller is usually used instead of the half moon roller 31. In this case, since the paper feed amount and movement amount are determined by the clutch driving time, it is necessary to control the clutch on-time and on / off timing. The timing of the on / off control is determined by the rotation speed of the paper feed roller 31 driven by the main motor M1 and the on time of the clutch. Further, when the registration roller 32 is rotating, the paper P is transported to the photosensitive drum 35 by the driving force of the registration roller 32 even if the paper supply roller 31 stops rotating.

  Next, the fed paper P is conveyed from the cassette by the rotation of the paper feed roller 31 and abuts against the registration roller 32. The registration clutch CL1 is driven so as to rotate the registration roller 32 after the registration roller 32 with which the paper P abuts obtains a predetermined loop amount of the paper P.

  From the on timing of the registration clutch CL1, when the paper P is transported and comes to a position where the photosensitive drum 35 and the transfer roller 34 come into contact with each other, the paper transport direction of the toner image created on the photosensitive drum 35 and the paper P Hereinafter, it is necessary to align the image position in the sub-scanning direction). If this control is not performed, the leading edge image and trailing edge image protrude from the sheet, and a desired image cannot be obtained. Therefore, the unit 1 synchronizes the writing timing of the image forming system on the photosensitive drum 35 with the on timing of the registration clutch CL1 that drives the registration roller 32 so that the unit 204 is positioned in the sub-scanning direction. To control the timing of image formation on the photosensitive drum 35. In the present embodiment, the distance L1 from the registration roller 32 to the transfer roller 34 is longer than the peripheral length L2 of the photosensitive drum from the laser irradiation position onto the photosensitive drum to the transfer roller 34. Therefore, the on-timing of the registration clutch CL1 is earlier. Accordingly, when the sheet P is conveyed by the registration roller 34 and the distance from the leading edge of the sheet P to the transfer roller 34 becomes L2, the timing for writing an image on the photosensitive drum 35 is determined. The image forming system will be described below.

  The developing kit 41 is provided with three charging portions for charging a high voltage created by the photosensitive drum 35 and the high-pressure unit 3 and developing toner. The three high-voltage charging units include a primary charging unit 2031 that charges the photosensitive drum 35, a developing charging unit 2032 that creates a toner image by attaching toner to an electrostatic latent image formed on the photosensitive drum 35, and a toner image. This is a transfer charger 2033 (charging roller 34 in FIG. 4) for transferring onto the paper P. In primary charging, it plays a role of making the potential of the photosensitive drum 35 a uniform white level. An electrostatic latent image is created on the photosensitive drum 35 by irradiating a laser according to an image signal from the laser scanner 40 onto the photosensitive drum. It is the development charge that plays the role of creating a toner image on the photosensitive drum 35 with the development charge and toner for the electrostatic latent image. It is the transfer charging unit that plays the role of transferring the toner image onto the paper P. In the embodiment, the charging roller 34 is charged by the fixing charging unit 2033 and the toner image on the photosensitive drum is transferred to the paper P.

  The unit 201 determines the timing for writing the laser from the laser scanner unit 40 onto the photosensitive drum 35 by the control described above in order to align the position of the toner image to be formed on the photosensitive member and the paper P in the sub-scanning direction.

  Further, the laser scanner unit 40 is prepared in accordance with the position in the main scanning direction of the paper P from a BD detection means (not shown) that determines the writing position on the photosensitive drum 35 in the laser scanning direction (hereinafter referred to as the main scanning direction). A function to automatically take the timing is attached. This is a function for preventing the left front edge image and the right rear edge image of the image from protruding from the paper. In accordance with the writing timing in the main scanning direction, a laser beam output as a signal obtained by converting the image signal into laser on / off is irradiated onto the photosensitive drum 35 by the reflection mirror 42, and a desired electrostatic latent image is formed on the photosensitive drum. Have created.

  By forming an electrostatic latent image on the photosensitive drum 35 at a position corresponding to the sub-scanning direction from the timing of the registration roller 32 and from the BD detection of the laser to the main scanning direction, the sheet P and the photosensitive drum conveyed by the registration roller 32 being driven. 35, the image created on the screen 35 is aligned. A toner image is formed on the electrostatic latent image formed on the photosensitive drum 35 by the control using the developing high-voltage portion in the developing kit 41 and the toner. In order to transfer the toner image onto the sheet P conveyed at the timing by the registration roller 32, the toner image is transferred onto the sheet P by the transfer roller 34 to which a high transfer charge is applied from the photosensitive drum 35. The toner image is transferred without protruding. Further, the toner image is thermally fixed on the paper P by the fixing roller 36. Further, the paper P that has passed through the vertical path 37 is discharged out of the apparatus by a paper discharge roller 38 that is driven by turning on the paper discharge clutch 2053 and is discharged onto the tray 39. Since the paper discharge clutch 2053 uses a round roller, at least the paper P needs to be turned on until it is discharged by the paper discharge roller 38. The above is the outline description of the image forming operation.

<Abnormality detection operation>
Based on the above description of the image forming operation, an outline of the abnormality detection operation according to the present invention will be described using the timing chart of FIG. FIG. 5 shows the driving timing of each load when an image is formed on one sheet. From above, M1 is a main motor, SL1 is a paper feed solenoid, CL1 is a registration clutch, M2 is a laser scanner unit, CL2 is a paper discharge clutch, FAN is a heat exhaust fan, primary is a high-voltage primary charging unit, and development is high-pressure development. A bias part and transfer represent a high-voltage transfer charging part. Each of them shows a state of not driving when “L” (low level portion of each signal), and shows a state of driving when “H” (high level portion of each signal). In addition, each unit in which a load is placed is separated by a square frame. Therefore, the load drive state changes at the timing of the image forming operation for each unit, so the current value at each timing is abnormally compared with the standard current consumption and the actual current consumption value. It is the outline of the present invention to judge that some abnormality is occurring in the load when the current is flowing large or the current value is abnormally small. In FIG. 5, there are loads that are activated simultaneously by a plurality of units, but as described in FIG. 6, the activation timing is shifted by a minute time.

  In FIG. 5, at timing a, for example, the main motor M1 (2021), the clutch CL1 (2023), the scan motor M2 (2041), the fan 2063, the primary charging unit 2031 and the developing charging unit 2032 are operating. The consumption currents of these loads are 1.0 A, 0.5 A, 0.8 A, 0.4 A, and 0.4 A, respectively. In units, the units 202, 203, 204, 205, and 206 are in the order of 1.5A, 0.4A, 0.8A, 0A, and 0.4A.

<Control unit>
FIG. 12 is a configuration block diagram of the control unit 201. The control unit 201 includes a power source / communication unit (means) 2012, and the control unit (means) 2011 is also mounted on the control unit 201. The control unit 2011 is configured by a microcomputer in this embodiment. An image forming operation is realized by controlling each unit from the control unit 2011 via the communication unit 2011.

  The storage unit 1 (2013) is a storage unit for storing information and calculation values obtained by the control unit 2011, and uses a RAM in the embodiment. Moreover, the arrow to each means has shown the direction which an effect | action acts. Since the RAM is readable and writable, it indicates that it is bidirectional. In the storage unit 2013, unit current measurement value tables 2013a to 2013e for the respective functional units 202 to 206 and abnormality flags 2013f to 2013j for the respective functional units are secured. In the unit current measurement value tables 2013a to 2013e, the measured values of the current consumed by the functional unit at a certain timing (predetermined timing) in the image forming operation sequence (for example, shown in FIG. 5) are stored in each functional unit and each Saved at each timing. In the abnormality flags 2013f to 2013j, an abnormality flag set for a functional unit determined to be abnormal by an abnormality detection operation described later is stored.

  The storage unit 2 (2014) is composed of a ROM, in which a program executed by the control unit 2011, a table necessary for control realized by execution of the program, and the like are stored in advance. The storage unit 2014 also stores a standard current value (unit standard current value tables 2014a to 2014e) at a predetermined timing in the image forming operation sequence for each functional unit, so that the control unit 2011 can read it when necessary. It has become. That is, the storage unit 2014 stores in advance a standard value of current consumption at a predetermined timing (for example, when there is a change in load) in the function execution operation sequence in each functional unit. This standard value is expressed in a unit system compatible with the measured current consumption value detected by the current detection circuit of the functional unit and transmitted to the control unit 201 by the control unit. In the present embodiment, the amperage is shown, but the present invention is not limited to this. The unit standard current value tables 2014a to 2014e are given an average value of current consumption of units that normally operate by, for example, measurement using functional units in a normal state in advance.

  The power source / communication unit 2012 includes a power source. This power supply is a means for supplying DC power (Vcc and GND). The power source / communication unit 2012 performs communication with each functional unit by superimposing a communication signal on two power lines, a Vcc line and a GND line. The received content can be obtained by demodulating the superimposed communication signal with the counterpart functional unit. The communication contents are modulated and superimposed on the power line to realize communication between the units. Each functional unit controls the contents received from the demodulated signal and controls the contents using the transmission contents and data, and determines the information and control contents for the next command.

  Further, the power source / communication unit 2012 and the control unit 2011 are connected by a bidirectional arrow in order to exchange information. An instruction is issued from the control unit 2011 to each functional unit via the power communication unit 2012, and information on sensors and current consumption values is obtained, thereby realizing an image forming operation and control according to the present invention.

  Since the image forming apparatus of the present embodiment is a printer, an image forming operation is performed in response to an image request from the external interface 2042 of the unit 204. In the embodiment, when printing is requested from an external personal computer or the like, it is input to this external interface (in this embodiment, a USB terminal). The units arranged in the apparatus are divided into a paper transport unit 202, a high voltage unit 2032, an image forming system unit 204, a paper transport unit 205, and a fixing system unit 206 as shown in the block diagram of FIG. The load is driven from each unit in response to the communication command, and information from each unit is transmitted to the unit 201. In this embodiment, the allocation of the load to the unit is considered so that the wiring length to the load is as short as possible according to the arrangement of the load, so that the cost of the bundled wires is reduced by collecting the loads close to each unit. I have to. When the control means 1 of the unit 1 detects through communication that an image formation request signal has been received from the external interface means, it sets the number of images and the image formation mode according to the given print mode.

  As described with reference to FIGS. 2 and 4, the main motor M <b> 1 of the unit 2 is driven by communication using the power line from the unit 1. After the time when the rotation of the main motor M1 is stabilized, a command to drive the sheet feeding solenoid SL1 of the unit 2 is performed by communication. During this time, the unit 3 initializes the photosensitive drum 35 to prepare for creating an image on the photosensitive drum, and the unit 6 raises the fixing temperature to a temperature at which the toner can be fixed.

  When the paper feed solenoid SL1 is turned on, the paper P set in the cassette is fed from the drive of the main motor M1. Further, the paper feed roller 31 rotates to secure the loop amount of the paper P after it hits the registration roller 32. After that, in order to align the leading edge of the image of the photosensitive drum 35 and the leading edge of the paper, the alignment in the sub-scanning direction is performed by synchronizing the timing of the registration clutch and the laser writing timing of the image forming system. The main scanning direction is automatically performed by the laser scanner unit 40 as described above.

  In addition, sensors are provided at necessary places for the purpose of monitoring the conveyance state of the paper P and the presence or absence of the paper, that is, detecting whether the paper P is jammed in the middle of the conveyance path. In the present embodiment, a paper remaining detection sensor for checking whether or not there is paper in the cassette, the paper P is fed from the cassette when the paper feed roller rotates, and whether or not the paper P has reached the registration roller 32, the registration clutch CL1. Is turned on, whether or not the paper P has been normally conveyed by the registration roller 32, whether or not the paper P has normally reached the fixing device 36 after transfer, and whether or not the paper P has been normally discharged from the paper discharge roller 38 A series of sensor groups, such as a paper discharge sensor for checking whether or not, is provided. To monitor the paper transport with these sensors, when a paper jam occurs on the way, it informs the outside that the paper is jammed, and prompts the user to jam the paper P that caused the paper jam. Necessary sensor group.

<Abnormality detection control>
Hereinafter, the control unit 201 detects the load abnormality of each functional unit from the information of the current detection means provided in each functional unit and the standard consumption current value, and describes the control for identifying the functional unit in which the abnormality has occurred. Do. In the second embodiment, a procedure for specifying a load having an abnormality among functional units in which an abnormality has been detected will be described.

  The control unit 201 communicates with each of the functional units 202 to 206 to obtain current consumption information from a current detection circuit provided in each functional unit. And it writes in the memory | storage part 2013 which has in the control unit 201. FIG.

  The control unit 201 communicates with each unit at the timing described with reference to FIG. 6, and transmits a command and timing for controlling the load by communication each time. The unit to be controlled communicates information such as the current consumption value and sensors at that time to the control unit 201. A communication method and timing will be described with reference to the timing chart of FIG.

  Timing signals t1 to t5 are signals indicating communication timing between the control unit 201 and each functional unit. The timing drawn with an arrow (↑) in each signal indicates the communication timing between the control unit 201 and each functional unit. That is, it corresponds to the rising edge (or falling edge) of each signal. The timing signal t0 indicates a basic clock for generating the timing signals t1 to t5. In this embodiment, the basic clock t0 is divided by 5, and the phase of each signal is shifted by one basic clock period to generate timing signals t1 to t5 for communication with the five functional units 202 to 206. Yes. Therefore, if there are N units, the basic clock is divided by N to generate a timing signal. The generation of the timing signal is performed by the power supply / communication unit 2012, for example. The timing signal t1 indicates that it is generated by dividing the basic clock t0 by five. Timings with circles 1a to 18a are created from timings with ellipses. The timing signal t1 generated in this way is used for the communication timing between the control unit 201 and the functional unit 202. Similarly, the timing signal t2 is the communication timing between the control unit 201 and the functional unit 203, hereinafter the timing signal t3. Is used to determine the communication timing between the control unit 201 and the functional unit 206, and the timing signal t4 is used to determine the communication timing between the control unit 201 and the functional unit 206. In this way, the control unit 201 realizes communication with other functional units in a time division manner. Note that communication between the control unit 201 and each functional unit includes a communication rate and data length so that it is completed within a period of one basic clock cycle, including a command from the control unit 201 to each functional unit and a response to the command. Is defined. Or conversely, the basic clock period may be determined from the realizable communication rate and the maximum data length.

  In the case where the communication rate exceeds a practical value when the number of functional units is large, a configuration having a plurality of sub-control units is also possible. In this case, the main control unit that supervises the sub control unit is set as the apex, the sub control unit group for controlling the unit group is provided in the lower layer, and the functional unit group is further provided in the lower layer (FIG. 18). ). In this case, the same effect can be obtained by the main control unit sucking up information once stored in the control unit group and performing control of image forming operation and abnormality detection with the main control unit. In this case, as shown in FIG. 18, the power supply voltage V1 between the main control unit and the sub control unit and the power supply voltage V2 (V1> V2) between the sub control unit and the functional unit group are configured. The same effect as the embodiment can be obtained.

  In the timing signals t1 to t5 in FIG. 6, the timings for communicating with the respective functional units are distinguished by adding suffixes a to e to the numbers 1 to 18 indicating the timings. For example, the timing 1a indicates a timing at which communication between the control unit 201 and the unit 202 is performed. Hereinafter, similarly, the timing 1b indicates the communication timing between the control unit 201 and the unit 203.

  Hereinafter, an example of communication and control between the control unit 201 and the unit 202 will be described with reference to FIG. 7 showing a timing chart of the load control. FIG. 7 is a diagram illustrating a timing chart for controlling each load in the unit 202 when printing on two sheets of paper. In the unit 202, a main motor M1, a paper feed solenoid SL1, a registration clutch CL1, and other paper detection sensors are mounted as loads.

  The timing signal t1 in FIG. 7 is the same as the timing signal t1 in FIG. At timing 1a in FIG. 7, control is performed from the control unit 201 to the unit 202 by communication so as to drive the main motor M1. For example, information indicating that the destination is the unit 202 and information (command) instructing to start driving the main motor M1 are transmitted from the control unit 201 to the unit 202. The unit 202 demodulates the signal by the communication circuit 5011 and analyzes the data. As a result, for example, if the destination is the unit 202, the contents of the instruction are further analyzed. If the drive command is for the main motor M1, the main motor M1 is driven. Accordingly, the timing for driving the main motor M1 is delayed from the timing 1a by a communication time, an analysis time, and the like. This is the part indicated by the arrow 701 in FIG. Similarly, the control unit 201 issues a command to the unit 202 at the communication timing (arrow indicated by a symbol) with an ellipse, and the unit 202 side performs a timing according to the command (the circle indicated by the arrow). The drive is driven / not driven at the timing indicated). In addition, when the power line is insulated for each functional unit, or at least with respect to the signal frequency, the communication destination is limited, so there is no need to attach a destination to the command.

  Thus, at timing 2a (arrow 702), the feeding solenoid is driven, at timing 3a (arrow 703), the registration clutch is driven, at timing 5a (arrow 704), the feeding solenoid is stopped, and at timing 7a (arrow 705), the registration clutch is driven. Stop, timing 10a (arrow 706) drives the feed solenoid, timing 11a (arrow 707) drives the registration clutch, timing 13a (arrow 708) stops the feed solenoid, and timing 15a (arrow 709) At the stop timing 18a (arrow 710), commands are sent to the unit 202 in the order of stopping the main motor M1, and the unit 202 operates according to the commands. This sequence is stored in advance in the storage unit 2014, for example, and the control unit 2011 of the control unit 201 reads it according to the timing signal t1 and transmits it to the unit 202. The same applies to other functional units.

(Unit standard current value table and error detection processing overview)
Here, the current consumption of each load of the functional unit 202 is 1 A (ampere) for the main motor M1, 0.3 A for the paper feed solenoid, and 0.5 A for the registration clutch CL1. The current consumption of the unit 202 at each timing shown in FIG. 7 is the total value of the current consumption of the loads driven at that timing. For example, at timing 1a, the only load that is driven is a sensor for paper detection or the like (the main motor M1 has not yet consumed current at this time), and the current consumption by this is very small. However, since consumption by a circuit other than the load such as the control unit 501 and the current detection circuit 502 of the unit 202 is 0.2 A, 0.2 A should be the consumption current of the unit 202. Therefore, the current value consumed by the unit 202 at the print start timing 1 a is stored in the unit standard current table 2014 a of the storage unit 2014 as 0.2 A. At timing 2a, since the main motor M1 is driven, 1 A flows in the main motor M1 and 0.2 A flows in the unit 202 itself, resulting in a consumption current value of 1.2 A in total. Accordingly, the unit standard current table 2014a of the storage unit 2014 stores 1.2A as the current consumption value at the timing 2a.

  Thus, the normal current value at normal time flowing through the unit 202 at a fixed timing is stored in the storage unit 2014 as a unit standard current table. In this embodiment, the timing for storing the standard current value is the timing synchronized with the timing signal for each functional unit. For example, for the unit 202, standard current values are stored for all of the timings 1a to 18a specified by the rising edge (or falling edge) of the timing signal. For this reason, even if there is no load to be driven at a certain timing, the control unit 201 transmits a command for transmitting the consumption current to each functional unit at that timing in order to acquire the consumption current value from the unit. However, the same effect can be obtained even if only the timing at which the current consumption value fluctuates is stored. In this case, a drive command is sent from the control unit 201 to each functional unit only when there is a load to be driven.

  A table 802 in FIG. 8 shows an example of a unit standard current value table for the unit 202 at the timings 1a to 18a shown in FIG. This is stored in the storage unit 2014 for each functional unit. Of course, the contents differ from unit to unit.

  A measured value 801 indicates an example of a current consumption value in the unit 202 when normally controlled. In normal times, as shown in FIG. 8, the contents of the current consumption value of the storage unit 2013 at each timing and the standard current consumption value stored in the unit standard current value table should show the same value. The same applies to other units as well as the unit 202.

  Taking the timing chart of FIG. 5 as an example, the standard current consumption value for each load is the current value shown in parentheses. Therefore, the total consumption current value (only the load) flowing to each functional unit at the timing 1a is 1.5A for the unit 202 (M1, SL1, CL1), and 0.4A for the unit 203 (primary, development, transfer). The unit 204 (M2) is 0.8 A, the unit 205 (CL2) is 0 A, and the unit 206 (FAN) is 0.4 A. Therefore, the standard current value in each functional unit is compared with the measured current consumption value, and if both are the same value or a difference equal to or less than a predetermined value as a result of the comparison, it is determined that the functional unit is normal. be able to. On the other hand, if there is a difference greater than or equal to a predetermined value, it can be determined that an abnormality has occurred in the compared units. That is, the current consumption value at each timing of 1a to 18a in FIG. 7 is read from the functional unit to be monitored and stored in the storage unit 2013. The unit standard current value at each timing is read from the storage unit (ROM) 2014 and compared with each other. When the absolute value of the difference between the measured current consumption value and the standard current consumption value registered in the table is larger than a predetermined value, it can be determined that an abnormality has occurred in the unit 202. In addition, it is desirable to compare the current values in real time. In this case, the measured current values may be temporarily stored until the comparison process, and it is not necessary to prepare the measurement value tables 2013a to 2013e.

  The control unit 201 that has detected the abnormality notifies the outside from the USB terminal in the unit 204 that the abnormality has occurred, or displays on the display unit that displays the state of the image forming apparatus to indicate that an abnormality has occurred to the outside. I can inform you. Also, the set value that is abnormal due to the difference in the current value is the same as the obtained effect, whether it is set for each unit or the same value. In this embodiment, a set value is set for each unit.

  In a load such as a motor, a large starting current may flow for about several hundred milliseconds (several seconds for a motor used in a large apparatus) from the time of starting. Therefore, the time required for starting after driving the main motor M1 cannot be reduced to the rated current value. Therefore, the current consumption value of the unit measured during this period may not match the standard current value stored in the storage unit 2014. For this reason, the image forming apparatus of this embodiment is controlled so that the current consumption is measured after reaching the rated state. For example, if the time of about several hundred milliseconds is sufficiently shorter than the period of the timing signals t1 to t5, nothing is required in the functional unit. However, if the time of about several hundred milliseconds is about the same or longer than the period of the timing signals t1 to t5, the period from the motor driving to the unsteady state was measured in the unit having the motor as a load. Since the current consumption value is a value that is always determined to be an abnormality detection state, it is not used for abnormality detection.

  There are other reasons for this. Since the low resistance R1 is inserted in series in the load in order to measure the current value, the start-up time is further extended. When the image forming operation is performed in this state, the speed is not sufficiently increased, and the image forming operation is interrupted by a jammed jam sequence. In order to prevent the resistance provided for measuring the current value from causing a failure, the following control is performed.

  As described with reference to FIG. 5, when a large current is consumed, such as when the motor is started, the transistor Q1 for passing an overcurrent is turned on to perform control to prevent the influence of the resistor R1. Therefore, the current detection circuit is in a state where it cannot detect the current value. If the image forming apparatus is a low-speed machine, communication can be performed with a slow cycle. However, as the speed increases, the image forming operation cannot be controlled unless communication is performed at an early cycle. Therefore, it is necessary to perform communication even during the motor start-up time. Therefore, it is necessary to control the transistor Q1. In addition, as the performance of the image forming device, it affects the performance value of how many seconds it takes from the start of the operation to eject the imaged paper from the device, so this control is necessary to increase this performance value. It is. However, since the apparatus of the embodiment is a low-speed image forming apparatus, communication is performed without controlling the transistor Q1 at the communication timings 1a to 18a in FIG. The case where the current at the time of starting the motor flows at the communication timing will be described later. No explanation is given here.

(Abnormality detection processing procedure)
Next, a general flow of abnormality detection control of the functional unit is shown in FIG. 1 and will be described. The communication processing of FIG. 1 is a processing procedure for performing communication with each functional unit in synchronization with the basic clock shown in FIG. This processing procedure is a part of the control of the image forming apparatus, and monitors the contents of commands transmitted to each functional unit, drive timing, sensors, and the like, and communicates with a functional unit (referred to as a target unit) to be controlled. This process is started after all necessary information is prepared.

  The process of FIG. 1 is a process by the control unit 201 that is performed at a certain timing with respect to one unit. Therefore, the process of FIG. 1 is a process performed at timing 1a and timing 1b of FIG. 7, for example.

  In step S1, timing signals t1 to t5 obtained by dividing the basic clock signal t0 by 5 are sequentially selected in synchronization with the basic clock. Since each timing signal corresponds to a functional unit, this is synonymous with selecting a unit (target unit) for communication. For example, a quinary automatic counter to which the basic clock t0 is input as a clock signal is started in synchronization with the start of image formation. When the counter value is 0, the timing signal t1, when the counter value is 1, the timing signal t2, when the counter value is 2, the timing signal t3, when the counter value is 3, the timing signal t4, when the counter value is 4, the timing signal t5 Is selected. The count value of the quinary counter returns to 0 after 4. That is, the selected target unit is indicated by this counter value. If a programmable counter is used as the counter and is programmed to be an N-ary counter in accordance with the number N of functional units, it is possible to cope with a change in the number of functional units.

  Step S2 is a process for preparing communication by referring to a table in which contents to be communicated with the target unit, that is, instructions to load and information are stored. For example, this table is provided in the storage unit 2014 configured by a ROM. For this purpose, information specifying where the current timing is in the timing signal (for example, somewhere in timings 1a to 18a in timing signal t1) is also required. This information can be indicated by a timing counter. This timing counter can be realized, for example, by another automatic counter using the carry signal of the above-described N-ary automatic counter as a clock. The value of the timing counter indicates the timing in the image forming sequence. For example, if the counter value is 3, the current timing is timings 3a to 3e for the target units 202 to 206, respectively. Correspondence between the timing indicated by the timing counter and the image forming operation at that timing can be made, for example, using a table stored in the ROM. The image forming operation can be realized by a combination of operation sequences for each phase such as an operation sequence at the start of image formation, an image formation operation sequence for one sheet, and an operation sequence at the end. Therefore, an instruction sequence for each functional unit in each phase is prepared in advance. The instruction sequence or the like is selected in accordance with the progress of the value of the timing counter and used as an instruction for the target unit. Further, if the unit standard current table is defined in association with commands issued to each unit at each timing in the operation sequence, the standard current in the operation sequence can be easily determined. For example, if the timing counter is 1, the sequence for the first sheet is selected, and the instruction for each target unit is taken out. And abnormality detection is performed using the unit standard electric current value linked | related.

  FIG. 5 shows an example of the phase. Phase 501 corresponds to the sequence at the start of image formation, phase 502 corresponds to the formation of one image, and phase 503 corresponds to the sequence at the end of image formation. This description is merely an example, and other control methods may be employed.

  In step S3, information and a command are transmitted by communicating with the selected target unit, information received from the target unit is received and processed.

  In step S4, it is determined whether a print request signal is input from the external interface and printing is in progress. If printing is not in progress, the following processing is performed without performing the following control. If the print request signal is input and printing is started or printing is in progress, step S6 is performed.

  In step S5, the measured current value is received from the target unit and stored in the measured value tables 2013a to 2013f of the storage unit 2013. When describing the timing 1a, information indicating the current consumption value (for example, 0.2A) of the unit 202 is obtained through communication in this step, and the contents are stored in the RAM of the storage unit 2013. Similarly, at the timings 2a to 18a, the current consumption value obtained by communication is stored in the storage unit 2013 (measured value table 2013a). In step S3, a current value measured from the target unit may be obtained.

  In step S6, it is determined whether or not the information obtained through communication is 0A (or almost 0A). The measured value becomes 0 when the potential difference between both ends of the resistor R1 in FIG. 3 is 0, which is when the transistor 5023 is in a conductive state. In this case, since the current value cannot be measured, if the received measured current value is 0 A, it is determined that the transistor 5023 is conductive, and this routine is exited to perform the next process.

  In step S7, the absolute value of the difference between the unit standard current value stored corresponding to the current timing and the measured current value received in step S5 is calculated. That is, the absolute value ΔI of the difference between the actual current consumption value and the standard current consumption value is calculated. The unit standard current value to be compared can be easily specified by holding it in combination with, for example, an instruction to be issued at the current timing specified in step S2. This is as described above.

  In step S8, it is checked whether the absolute value ΔI of the difference is larger than a predetermined value I1 (in this embodiment, 0.2A). If it is normal, the value of ΔI does not become larger than I1, so that the process exits from this routine and performs the next process. If an abnormality has occurred, the difference in ΔI becomes larger than I1, so the process goes to step S9. The value of I1 may be determined, for example, by experimentally measuring the current value in the case of normality and the dispersion thereof.

  In step S9, an abnormality flag corresponding to the target unit is set. For example, when an abnormality such as disconnection or short-circuit occurs in the electric wire connected to the registration clutch CL1, ΔI increases because no current flows or a large current flows through the registration clutch CL1. When this ΔI is larger than I1, it is determined that an abnormality has occurred in the unit 202. The result is stored in the storage unit 2013. In this case, it is detected that an abnormality has occurred in the unit 202, and this is stored as an abnormality flag. Next, an abnormality process is performed in which the unit in which an abnormality has occurred is displayed on the operation unit, and the unit in which an abnormality has occurred is displayed externally from the USB terminal of the external interface. By performing the above control, it is possible to realize control for detecting which unit in the image forming apparatus has an abnormality.

(Processing in the target unit)
FIG. 13 is an example of a processing procedure in the target unit of the communication partner in step S3 of FIG. When a signal is received by the communication circuit 5011 and demodulated data is received by the control circuit 5012, the procedure of FIG. 13 is started.

  First, a value is read from the A / D converter 5022 and stored (S1301). However, this is not necessary when the transistor N is turned on by turning on the signal N. Next, a response to the normal reception is sent to the command (S1302). This response is received in step S5 of FIG. Next, the load is driven according to the received command (S1303). Finally, the current value stored in step S1301 is transmitted to the control unit 201 (S1304). However, if the measurement value is not read in step S1301, 0 is transmitted as the measurement value.

  By the above procedure, the control unit 201 can acquire the current value measured at a predetermined timing in each functional unit. Then, the presence or absence of a failure can be determined by comparing the current value with a standard value prepared in advance at the timing when the current value is measured.

  FIG. 9 shows an example of the current consumption value 901 and the standard current consumption value 802 of the unit 202 when the current of the paper feed solenoid SL1 does not flow (disconnection, etc.) before accepting the print request and before standby. It is the table | surface which showed. In this example, the value of ΔI is set to 0.2A. FIG. 9 shows the current consumption of the unit 202 during the image forming operation from 1a to 18a in FIG. 7 (that is, from the start to the end of image formation). 0 and 1 written in the table of the main motor M1 (M1), the sheet feeding solenoid SL1 (SL1), and the registration clutch CL1 (CL1) indicate 1 when driving and 0 when not driving.

  When FIG. 9 is seen, the value of (DELTA) I is larger than 0.2 by the area 3a-5a and the area 11a-13a, and it turns out that abnormality has generate | occur | produced in these areas. From this table, it can be specified that ΔI is 0.2 A or more and the load driven at that timing is the paper feed solenoid SL1. Therefore, it is possible to determine a period in which an abnormality has occurred and detect that the load in which the currently driven load coincides with the section to be driven is abnormal.

  However, in the above embodiment, normal jam detection and the like as described below operate. If the paper feed solenoid SL1 does not operate, the paper P in the cassette cannot be fed, so the paper P cannot be detected after the paper feed operation by the paper feed sensor. Therefore, it is determined that the paper P has jammed when the paper P must reach the sensor position after the paper feeding operation (arrival time + margin).

  As a result, an abnormality of the unit 202 is detected at the timing 3a, and then a paper feed jam is determined based on a signal from the sensor P. The image forming operation is normally interrupted when it is determined that the jam has occurred. For this reason, it is impossible for actual control that the sheet feeding solenoid SL1 is continuously executed with the abnormality until the end of the image forming operation. This is because if the operation is continued with the paper P in the image forming apparatus, for example, the paper P may be wound around the fixing roller 36 or the photosensitive drum 35 may be jammed. This is because priority is given to the control to stop if detected. For this reason, it can be determined which unit has an abnormality by the above method. However, it can be seen that the load is not specified.

  Therefore, in the above embodiment, there is no problem from the communication timings 1a to 2a because the difference is within 0.2A. However, since ΔI exceeds 0.2A at the time of communication 3a, the unit 202 is installed in step S8 of FIG. It can be detected as abnormal. Since the current value of ΔI exceeds 0.2 A, the control unit 2011 can notify the outside that an abnormality has occurred in the unit 202 via the operation unit or the external interface.

  In addition, the control method in case the electric current at the time of motor starting is related to communication timing is described. 10 and 11 are timing charts of load driving in the unit 202 when one sheet is printed. The main motor M1 is turned on, the paper feed solenoid is turned on, and the paper P is fed. After the fed paper P hits the registration roller 32 and secures a predetermined loop amount, the registration clutch CL1 is driven to rotate the registration roller 32. The following is a timing chart in the unit 202 until the main motor M1 is rotated until the paper P on which the image is formed and fixed is completely discharged, and the main motor M1 is stopped after the discharge.

  The timing chart of the signals to each load in the unit 202, that is, the three signals M1, SL1, and CL1 in FIG. 9, corresponds to the above description, and shows that the signals are driven when the signals are rising. At the timing when each load fluctuates (boundary between sections A to E in FIG. 10), the current consumption flowing in the unit 202 changes. About several hundred milliseconds when the main motor M1 starts up, the starting current is large, so the current during this period is a section that is significantly different from the standard current consumption value. The signal tx is a timing indicating the communication timing between the control unit 201 and the unit 202, and performs communication at the timing of the arrow. Although this is different from FIG. 6, it is for explaining an example of processing at the time of starting of the motor, and the example of FIG. 6 is applied in the same manner.

  Here, timings corresponding to timings 2 and 3 (arrows with circles) of the signal tx correspond to a period during which the starting current of the main motor M1 is flowing. For this reason, at timings 2 and 3, the current value of the main motor M1 is transmitted as 0A in communication. The control unit 2011 does not calculate ΔI because it is not a comparison target at timings 2 and 3 of tx. As described above, the value of the current flowing through the unit 202 is substantially constant in the section from A to E in FIG. It becomes 1.2A (except during communication of 2 and 3) in section A, 1.5A in section B, 2.0A in section C, 1.7A in section D, and 1.2A in section E. FIG. 11 shows a table in which this value is stored as a standard value in the storage unit 2014 and the current value actually flowing through the unit 202 is compared with the value stored in the storage unit 2013.

  In the table of FIG. 11, the current value is 0 between the timings 2 and 3. This is because during this time, as described in the explanation of FIG. 3, communication is performed within the time during which the starting current flowing when the main motor M1 starts, that is, when the current cannot be measured. That is, the transistor Q1 in FIG. 3 is turned on until the start-up current is settled and the influence of R1 is removed at the time of motor start-up, and therefore A / D conversion for current measurement is prohibited. Therefore, information of 0A is returned as a communication result. Therefore, the control with the consumption current value of the unit 202 is not performed between the timings 2 and 3. However, since the starting current flowing in the main motor M1 is within the standard current value at the timing after tx 4, the information from the current detection circuit is obtained, and the current value of the unit 202 is validated to detect an abnormality. I use it.

[Second Embodiment]
In the first embodiment, ΔI is calculated from a current consumption value and a standard current consumption value flowing through each functional unit at timings from 1 n to 18 n (n is a to e) for each functional unit, and ΔI is larger than a predetermined value. An abnormality was detected depending on whether it became larger. In this embodiment, the load causing the failure in each unit is further specified.

  FIG. 14 is a general flow performed by the control unit 201 after detecting an abnormality in the unit until determining which load in the unit caused the abnormality. This will be described below with reference to FIG. Steps S21 to S29 are the same control as in FIG. The abnormality control 1 in step S30 is a control that is performed when an abnormality accompanied by the occurrence of a jam occurs. Here, control for urging control to remove the paper P causing the jam is performed. Until normal jam processing is performed, the abnormality control 1 in step S30 is continued. The determination is made in step S31. Therefore, the abnormality control 1 is performed until the jam is released, and the jam processing is promoted.

  Step S32 is abnormal load determination control for determining an abnormal load for a unit determined to be abnormal. Here, in order to identify the abnormal load as described below, the abnormal load is identified by performing control according to the timing chart as shown in FIG. Hereinafter, description will be made with reference to FIG. 15 which is a detail of step S32.

  First, a timing signal is started (S1501). This corresponds to the signal t1 in FIG. Next, the target load is determined, and a command for driving the load is transmitted to the target unit (S1502). Then, the measured current value is received. The operation of the target unit is as shown in FIG. And the standard consumption current value memorize | stored corresponding to the drive target load is read from the memory | storage part 2014 (S1503). Then, it is determined whether the difference (absolute value) between the measured current value and the standard current value is within a certain value (S1504). If it is not within the predetermined value, an abnormality flag (provided in the storage unit 2013) corresponding to the target load is set in step S1505. This is repeated for all loads of the target unit (S1506). If not completed, the process waits until the next processing timing (that is, the driving timing of the next load) and repeats from step S1501.

  FIG. 16 shows a timing example of the processing sequence of FIG. In FIG. 16, M1 represents a main motor M1, SL1 represents a sheet feeding solenoid SL1, and CL1 represents a driving state of a registration clutch. “L” indicates a non-driving state, and “H” indicates a driving state. The control unit 201 sequentially drives the load connected to the unit 202 at each timing by communicating with the unit 202 by the arrow (↑) indicated by the timing t1 for the unit 202 detected as abnormal. Command to control.

  When the jam is released at one timing of the signal t1, the control unit 201 sends a command for driving the paper feed solenoid SL1 to the unit 202 by communication at a timing 1601. It is driven when the solenoid SL1 has an ellipse on the unit 202 side. Next, at timing 1602, simultaneously with the release of the drive of the paper feed solenoid SL1, the registration clutch CL1 is driven. At timing 1603, the main motor M1 is driven and at the same time the registration clutch CL1 is released. Next, at timing 1604, the drive of the main motor M1 is released. In this way, the load connected to the unit 202 is caused to act in order to drive. The load state is controlled such that the section indicated by arrow A is driven by only the feed solenoid SL1, the section indicated by arrow B is driven only by the registration clutch CL1, and the section indicated by arrow C is driven only by the main motor M1. . The section indicated by the arrow D is the current of the unit 202 itself, and the section indicated by the arrow E indicates a state where the starting current is flowing through the main motor M1. This completes the abnormal load determination control. For this purpose, a table storing current consumption for each load in advance is also prepared in the storage unit 2014.

  FIG. 17 is a table showing ΔI that is the difference between the current value flowing through the unit 202 during the abnormal load determination control and the standard current value. The signal t1 indicates timing and corresponds to the timings 1, 2, 3, 4,... Of the signal t1 in FIG. The main motor M1 (M1), the paper feed solenoid SL1 (SL1), and the registration clutch CL1 (CL1) shown in FIG. 17 show the driving state of the load at that time. 1 indicates a driving state and 0 indicates a non-driving state. The standard current value 1701 (storage 2) flowing through the unit 202 is stored in the storage unit 2014, and the consumption current value 1702 is stored in the storage unit 2013 (storage 1). Since the feed solenoid SL1 is disconnected, it can be seen that the period from the timing 3 to the timing 10 of the signal t1 (arrow A section) is abnormal because ΔI is 0.2 A or more. Since both the next timings 11 to 18 (arrow B section) are 0.7 A, ΔI <0.2 A, and therefore it is determined that the registration clutch CL1 is normal. Next, since the timing 19 to 26 (arrow C section) is also 1.2 A, it is determined that the main motor M1 is normal. However, since the starting current of the main motor M1 flows during the period of the timings 19 to 21, it is not a comparison target period, so ΔI is written as xx.

  As described above, it is possible to identify an abnormal load by sequentially driving the load and comparing the standard current consumption value and the current consumption value. The reason why a plurality of loads are not driven at the same time is to prevent paper P from being fed into the image forming apparatus by driving the paper feed solenoid SL1 while driving the main motor M1, for example. It is also for the purpose. If the sheet feeding is not performed, the operation to drive only the load does not damage the image forming apparatus. Therefore, the damage is prevented by sequentially driving the load as described above.

  The abnormality control 2 in step S33 is a routine for informing the outside that an abnormality has occurred, and displays and informs the operation unit having a display unit for displaying the load in which the abnormality is specified. Alternatively, it is a control for specifying and notifying a load in which an abnormality has occurred to the outside from a USB terminal which is an external interface for transmitting to the outside. If the load with an abnormality is identified in this way, the display unit or external interface notifies the outside that a failure has occurred, and the failure of the specified load at the failure location is also notified, where the abnormality occurs. It is possible to inform the user of whether or not

  Step 34 is a determination for not accepting the image forming operation until the abnormality is canceled and a cancel command is input from a device such as a personal computer connected via the operation unit or the external interface.

  As described above, according to the embodiment of the present invention, when an abnormality occurs in the image forming apparatus, the failure unit can be identified by comparing the standard average current and the actual consumption current.

  Further, by examining the difference from the current consumption value and the average current value at a finer timing, it is possible to identify which load in the failed unit caused the abnormality.

  The result can be notified to a user or an administrator of the apparatus using a display unit or an external communication means.

It is the general flow which the control means which is this invention performs. 1 is a block diagram illustrating a configuration of an image forming apparatus that performs communication through a power line. It is explanatory drawing of the electric current which flows into each load with the timing chart of image formation operation | movement. It is the block circuit of the electric current detection circuit, communication means, and control part which were provided in each functional unit which is this invention. 1 is a cross-sectional view of an example of an image forming apparatus. It is a timing chart of communication timing generation with each functional unit. 4 is a timing chart showing communication timing and load driving timing in a unit 202. It is the table | surface which showed the content memorize | stored in the current consumption in the unit 202 at the timing shown in FIG. 7, and a memory | storage means. It is explanatory drawing of the table | surface which showed the timing judged to be abnormal from the drive state in each timing when a sheet feeding solenoid of the unit 202 becomes abnormal, the standard current consumption value, and the current consumption value. It is a timing chart which shows the communication timing for specifying the load where abnormality occurred, and the area which each load is driving. It is explanatory drawing of the table | surface which showed the electric current value at the time of normal time and the time of abnormality in the communication timing for specifying abnormality, and the area which each load is driving. Further, it is a table of control when the main motor starting current is flowing, and is an explanatory diagram. FIG. 3 is a block diagram constituting a control unit 201. It is a processing procedure of the target unit that has received a command from the control unit. It is a general flow for controlling until a load is specified. It is a general flow for controlling until a load is specified. It is a timing chart which drives the load for specifying a load. It is a table | surface which shows the electric current value in each area based on the timing of FIG. 14, and is explanatory drawing for pinpointing a load from the area judged to be abnormal. It is a block diagram with a hierarchical functional unit group.

Claims (10)

An image forming apparatus,
A plurality of functional units that are divided into functions of the image forming apparatus and that include a current measuring unit that measures a current consumption value and an output unit that outputs the measured current consumption value;
For each of the plurality of functional units, storage means for storing in advance a unit standard value which is a standard of current consumption at a predetermined timing of an operation sequence of function execution;
The current consumption value at the predetermined timing is received from the target functional unit identified from among the plurality of functional units, and compared with the standard value at the corresponding timing stored in the storage means, and a difference greater than or equal to the predetermined value An image forming apparatus comprising: a control unit that determines that an abnormality has occurred and outputs information indicating that the function unit has an abnormality to the outside.   The image forming apparatus according to claim 1, wherein the control unit compares a current consumption value with a standard value using each of the plurality of functional units as the target functional unit. The storage means further stores, for each of the plurality of functional units, a load standard value that is a standard of current consumption for each load belonging to the functional unit,
When it is determined that an abnormality has occurred in the target functional unit, the control unit sequentially drives the load belonging to the target unit, compares it with the load standard value, and when there is a difference of a predetermined value or more. The image forming apparatus according to claim 1, wherein the image forming apparatus determines that an abnormality has occurred and outputs information indicating that the load has an abnormality to the outside.   The output means outputs a current consumption value measured when a predetermined time elapses after starting the load to the control means when the predetermined timing is when driving a load through which a large current flows at startup. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. A plurality of units that control or drive a plurality of loads and execute a function classified for each function of the image forming apparatus, and communicate with each other with a control unit that controls the plurality of units. An image forming apparatus that performs an image forming operation by performing control,
Each unit includes a current detection means for detecting current consumption consumed by the unit, a control unit and a communication means, controls the unit itself, communicates information obtained by the unit to the control unit, and performs control. The load is controlled by the communication command from the unit,
In the control unit, from each storage unit storing a standard current consumption value consumed by each unit at each timing when driving of the load is changed by executing an image forming operation in each unit, from the storage unit to the storage unit At the timing corresponding to the stored standard consumption current value, the consumption current value detected by the current detection unit is received from each unit, the current value is compared with the standard consumption current value read from the storage unit, An image forming apparatus that outputs that an abnormality has occurred when a difference of a predetermined value or more is detected.   6. The image forming apparatus according to claim 1, wherein each unit and the control unit communicate with each other by superimposing a communication signal on a power line for supplying power from the control unit to each unit. apparatus.   In the case of a load such as a motor that causes a large current to flow at the start of the load with the current consumption of each unit, the comparison information of the comparison means is ignored for a predetermined time from the start, and the predetermined value or more is exceeded even after the predetermined time has elapsed. 7. The image forming apparatus according to claim 1, wherein when it is detected that there is a difference between the two, an abnormality is determined so that the abnormality is determined and an abnormality is notified. 7. A plurality of functional units that are classified by function and have current measuring means for measuring the current consumption value and output means for outputting the measured current consumption value;
For each of the plurality of functional units, an electronic apparatus comprising storage means for storing in advance a unit standard value that is a standard of current consumption at a predetermined timing of an operation sequence for performing functions,
Receiving a current consumption value at the predetermined timing from a target functional unit identified from the plurality of functional units;
A comparison step for comparing with a standard value at a corresponding timing stored in the storage means;
If there is a difference greater than or equal to a predetermined value as a result of the comparison, the abnormality location is characterized by comprising an output step of determining that an abnormality has occurred and outputting information indicating that the function unit has an abnormality to the outside Identification method. The storage means further stores, for each of the plurality of functional units, a load standard value that is a standard of current consumption for each load belonging to the functional unit,
When it is determined in the comparison step that an abnormality has occurred in the target functional unit, the load further belongs to the target unit, and a second comparison step for comparing with the load standard value is further provided.
9. The output step is characterized in that, if there is a difference of a predetermined value or more as a result of the comparison in the second comparison step, information indicating that the load is abnormal is output to the outside. The method for identifying an abnormal part as described in. A plurality of functional units, each of which is divided by function, and includes a current measuring means for measuring a consumption current value and an output means for outputting the measured consumption current value;
For each of the plurality of functional units, storage means for storing in advance a unit standard value which is a standard of current consumption at a predetermined timing of an operation sequence of function execution;
The current consumption value at the predetermined timing is received from the target functional unit identified from among the plurality of functional units, and compared with the standard value at the corresponding timing stored in the storage means, and a difference greater than or equal to the predetermined value An electronic device capable of detecting an abnormality on a functional unit basis, comprising a control means for determining that an abnormality has occurred and outputting information indicating that the functional unit has an abnormality to the outside. apparatus.

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