JP2008015327A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of surely and suitably suppressing the drive of at least a part of actuators without being influenced by the runaway or the like of a CPU when the apparatus is abnormal or the like. <P>SOLUTION: Composite ICs 210, 220 mutually input their own overcurrent detection and thermal shutdown information as alarms and an alarm inputted from the composite IC 220 to the composite IC 210 is inverted and inputted to an AND circuit 215. A first fan ON signal for driving a first fan drive motor 255 is also inputted to the AND circuit 215, the AND operation result of the AND circuit 215 is further inputted to an AND circuit 216 together with a motor drive enable signal (Enable) to a belt drive motor 261, and the AND operation result of the AND circuit 216 is inputted to a first motor driver 212. Namely during a period except when an alarm is not generated in the composite IC 220 and the first fan ON signal is outputted, the motor drive enable signal is invalidated. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image forming apparatus that forms an image on a recording medium by an electrophotographic method, and more particularly, to an image forming apparatus that can suppress driving of some actuators when the apparatus is abnormal.

  Conventionally, an image forming apparatus including an image forming unit that forms an image on a recording medium by an electrophotographic method and a conveying unit that conveys the recording medium through the image forming unit has been considered. In this type of apparatus, when the recording medium is conveyed through the image forming means by the conveying means, an image can be formed on the recording medium by the electrophotographic method by the image forming means.

Also, with this type of device, there may be inconveniences when some actuators are driven when there is some abnormality in the device. Therefore, for example, in an apparatus that controls various motors in the image forming apparatus by software, it has been proposed to stop the motor when a timeout occurs during driving of the motor (see, for example, Patent Document 1). .
JP-A-9-120232

  However, in the case where the control for the abnormality of the apparatus is performed by software, if the CPU runs away, it becomes impossible to cope with the abnormality. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an image forming apparatus capable of appropriately suppressing at least a part of actuators without being affected by a CPU runaway or the like when the apparatus is abnormal. It was.

  An image forming apparatus of the present invention made to achieve the above object includes an image forming unit that forms an image on a recording medium by an electrophotographic method, a conveying unit that conveys the recording medium through the image forming unit, An image forming apparatus comprising: a motor that is provided inside the image forming apparatus and that drives an internal mechanism of the image forming apparatus; a motor driving unit that drives the motor; and the interior of the image forming apparatus. Fan driving means for driving a fan motor for driving a fan to be cooled, and first safety control means for allowing the motor to be driven on the condition that the fan motor is driven. The drive means, the fan motor drive means, and the first safety control means are formed in a common first IC.

  In the image forming apparatus of the present invention configured as described above, the first safety control means forms the image on the condition that the fan motor for driving the internal cooling fan of the image forming apparatus is driven. Allows driving of a motor that drives the internal mechanism of the apparatus. In addition, the first safety control means is formed in the first IC. For this reason, in the present invention, the motor and the IC provided with the motor driving means for driving the motor may be overheated by driving the motor even though the fan is not driven. Even if the CPU runs away, it can be reliably suppressed without being affected by the runaway. Moreover, in the present invention, since the first safety control means is formed in the first IC that is common to the fan driving means for driving the fan and the motor driving means, the configuration is simplified and the manufacturing cost is reduced. In addition, it is possible to suppress malfunction due to noise or the like.

  The image forming apparatus of the present invention is not limited to the following configuration, but further includes an overcurrent detection unit that is formed in the first IC and detects an overcurrent of the motor. The first safety control means may stop the driving of the motor when the overcurrent detection means detects an overcurrent. In this case, when the overcurrent detection means formed in the first IC common to the first safety control means detects the overcurrent of the motor, the first safety control means stops driving the motor. Therefore, even if an overcurrent is supplied to the motor, even if the CPU runs away, it can be reliably suppressed without being affected by the runaway. Further, the first safety control means may be constituted by a hard logic circuit, and in this case, the influence of the CPU runaway or the like can be more effectively eliminated.

  Further, when the motor drives at least the conveying means, a first solenoid for switching transmission / non-transmission of the driving force of the motor to the recording medium and a first solenoid are formed in the first IC. The first solenoid driving means for driving the first solenoid and the first solenoid driving means that are formed in the first IC and permitting the driving of the motor are permitted. And a second safety control means.

  While the motor is stopped, it does not make sense to drive the first solenoid that switches between transmission / non-transmission of the driving force of the motor to the recording medium. The driving of the first solenoid can be permitted on the condition that the driving of the motor is permitted by the safety control means. Moreover, the second safety control means is also formed in the first IC. For this reason, when the above configuration is adopted, unnecessary operation of the first solenoid can be reliably suppressed without being affected by the runaway even if the CPU runs away. In addition, since the first solenoid driving means and the second safety control means for driving the first solenoid are formed in the common first IC, the configuration is simplified and the manufacturing cost is reduced. In addition, malfunction due to noise or the like can be suppressed. Further, the second safety control circuit may be configured by a hard logic circuit, and in this case, the influence of the CPU runaway or the like can be more effectively eliminated.

  Still further, in the first IC, a timing control means for measuring the time and controlling the first solenoid based on the timing result may be formed. In this case, various controls such as, for example, not driving the first solenoid continuously for a predetermined time or longer can be executed based on the time measurement result by the time measurement control means.

  The image forming apparatus according to each aspect of the invention includes a cleaning motor for driving the cleaning mechanism of the conveying unit, a cleaning motor driving unit for driving the cleaning motor, and a contact and separation of the cleaning mechanism with respect to the conveying unit. That the second solenoid for switching, the second solenoid driving means for driving the second solenoid, and the motor driving means formed in the first IC are operating normally. And a third safety control means that allows the driving of the cleaning motor and the second solenoid under conditions, the cleaning motor driving means, the second solenoid driving means, and the third safety control means It may be formed in a common second IC.

  When such a configuration is adopted, a cleaning motor for driving the cleaning mechanism of the transport means by the third safety control means, and a second solenoid for switching the contact and separation of the cleaning mechanism to the transport means Can be allowed on condition that the motor driving means formed in the first IC is operating normally. In addition, the third safety control means is formed in the second IC. Therefore, when the above configuration is adopted, unnecessary operations of the cleaning motor and the second solenoid can be reliably suppressed without being affected by the runaway even if the CPU runs away. The third safety control means is formed in a second IC common to the cleaning motor driving means for driving the cleaning motor and the second solenoid driving means for driving the second solenoid. Therefore, the configuration can be simplified to reduce the manufacturing cost, and malfunction due to noise or the like can be suppressed.

  Furthermore, since the second IC has substantially the same structure as the first IC, it is possible to share components. The second IC is mainly required in a color image forming apparatus, and the first IC is required for both monochrome and color, but two first ICs for monochrome are used and one of them is the first. By using the IC of 2, it is possible to cope with a color image forming apparatus. Therefore, according to the present invention, the manufacturing cost of the color image forming apparatus can be further reduced, and the safety of the apparatus can be ensured as described above.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic sectional view showing the internal configuration of a color laser printer (hereinafter simply referred to as a printer) 1 as an image forming apparatus to which the present invention is applied.

  A printer 1 illustrated in FIG. 1 includes a toner image forming unit 4 as an example of an image forming unit, a paper conveying belt 6 as an example of a conveying unit, a fixing unit 8, a paper feeding unit 9, a stacker 12, The image forming apparatus includes a control unit 10 and forms four-color images according to image data input from the outside on a sheet P as a recording medium.

  The toner image forming unit 4 includes four developing units 51Y, 51M, 51C, and 51K, and yellow, magenta, cyan, and black toners T (stored in these developing units 51Y, 51M, 51C, and 51K. For each of the four toner image forming steps (corresponding to the developer: see FIG. 2), the photosensitive drum 3 as the photosensitive member, the charger 31 for uniformly charging the photosensitive drum 3, and the photosensitive after the charging A scanner unit 41 is provided as an exposure unit that exposes the surface of the body drum 3 with laser light to form an electrostatic latent image according to image data. Note that most of the scanner unit 41 is not shown, and only a portion where laser light is finally emitted is shown.

  Hereinafter, the configuration of each component will be described in detail. In the following description, when it is necessary to distinguish each color, it is necessary to add a suffix of Y (yellow), M (magenta), C (cyan), K (black) to each part code. If there is not, the subscript is omitted.

  The photosensitive drum 3 of the toner image forming unit 4 is formed of a substantially cylindrical member, and four of them are arranged in a horizontal direction at substantially equal intervals so as to be rotatable. As the substantially cylindrical member of the photosensitive drum 3, for example, a member in which a positively chargeable photosensitive layer is formed on an aluminum base material is used. The aluminum base material is grounded to the ground line of the printer 1.

  Further, the charger 31 is a so-called scorotron type charger. The charger 31 is opposed to the photosensitive drum 3 and extends in the width direction thereof. The charging wire 32 is accommodated in the photosensitive drum 3 side. The surface of the photosensitive drum 3 is charged to a positive polarity (for example, +700 V) by applying a high voltage to the charging wire 32. The shield case 33 has a structure in which a grid is provided in the open portion on the photosensitive drum 3 side. By applying a specified voltage to the grid, the surface of the photosensitive drum 3 is substantially the same as the grid voltage. Charged to potential.

  The scanner unit 41 is disposed on each photosensitive drum 3 on the downstream side of the charger 31 in the rotation direction of the photosensitive drum 3, and emits laser light corresponding to one color of image data input from the outside from the light source. The laser beam is emitted by a mirror surface of a polygon mirror that is emitted and rotated by a polygon motor 265 (see FIG. 3), which will be described later, and is irradiated onto the surface of the photosensitive drum 3.

  When the scanner unit 41 irradiates the surface of the photosensitive drum 3 with laser light corresponding to the image data, the surface potential of the irradiated portion is reduced (+150 to +200 V), so that the photosensitive drum 3 An electrostatic latent image is formed on the surface.

  Each of the developing units 51Y, 51M, 51C, and 51K includes a developing unit case 55 that stores toner T of each color and a developing roller 52 as a developing unit. Thus, the developing roller 52 is disposed on the downstream side of the scanner unit 41 so as to contact the photosensitive drum 3. Each developing unit 51 charges the toner T to “+” (positive polarity), supplies the toner T to the photosensitive drum 3 as a uniform thin layer, and at the contact portion between the developing roller 52 and the photosensitive drum 3, With respect to the “+” (positive polarity) electrostatic latent image formed on the photosensitive drum 3, a toner T charged to “+” (positive polarity) is carried by the reversal development method, and the electrostatic latent image is formed. Develop.

  The developing roller 52 is formed in a cylindrical shape using a conductive silicone rubber or the like as a base material, and a coating layer of a resin containing fluorine or a rubber material is formed on the surface. The toner T stored in the developing unit case 55 is a positively chargeable non-magnetic one-component toner, and yellow, magenta, cyan, and black toners according to the developing units 51Y, 51M, 51C, and 51K, respectively. T is housed.

  The paper feeding unit 9 is provided at the lowermost part of the apparatus, and includes a storage tray 91 that stores the paper P and a paper feed roller 92 that feeds the paper P. Then, the paper P stored in the storage tray 91 is taken out one by one from the paper supply unit 9 by the paper supply roller 92, and is sent to the paper transport belt 6 through the transport roller 98 and the registration roller 99.

  The sheet transport belt 6 is narrower than the width of the photosensitive drum 3 and is endlessly configured to travel integrally with the sheet P while the sheet P is supported on the upper surface. It is bridged between. In addition, transfer rollers 61 are provided in the vicinity of positions facing the respective photosensitive drums 3 with the paper transport belt 6 interposed therebetween. Then, as the driving roller 62 rotates, the surface of the sheet conveying belt 6 facing the photosensitive drum 3 moves from the right in the drawing to the left in the drawing as shown in FIG. The paper P sent from the roller 99 is sequentially conveyed to the photosensitive drum 3 and sent to the fixing device 8.

  In addition, a cleaning roller 105 as an example of a cleaning mechanism is provided at a position near the driven roller 63 on the surface turned back by the driving roller 62 of the paper transport belt 6. Further, a detection sensor 111 as a pattern detection unit is provided at a position facing the paper conveyance belt 6 on the driving roller 62. The detection sensor 111 is a reflective sensor (for example, product name “GP2TC2”: manufactured by Sharp) that has one light-emitting unit and a plurality of light-receiving units and identifies a color based on a light reflection angle.

  FIG. 2 is an explanatory diagram illustrating in detail the configuration of the belt cleaner 100 including the cleaning roller 105. As shown in FIG. 2, the cleaning roller 105 has a configuration in which a foam material made of silicone is provided around a shaft member 105 </ b> A extending in the width direction of the paper transport belt 6. A predetermined bias is applied between the metal electrode rollers 104 provided at the opposing positions, and the roller is arranged to rotate while being in contact with the paper transport belt 6. With this bias, the toner T adhering to the paper transport belt 6 is removed by the cleaning roller 105. For example, if the electrode roller 104 is connected to the ground line and grounded, and a bias (for example, −1200 V) having a polarity opposite to the polarity of the toner T is applied to the cleaning roller 105, the toner T is attracted to the cleaning roller 105. Can be removed. The cleaning roller 105 can be driven by a fixing & belt cleaner motor 267 (see FIG. 3) as an example of a cleaning motor, which will be described later, so that the contact portions with the paper transport belt 6 are in opposite directions.

  Further, the cleaning roller 105 includes a metal recovery roller 106 that removes the toner T adhering to the cleaning roller 105 from the cleaning roller 105 (for example, a structure in which an iron material is plated with Ni or a structure made of stainless steel). And a storage box (storage container) 107 for storing the toner T removed from the cleaning roller 105. A rubber cleaning blade 108 is in contact with the collection roller 106, and this cleaning blade 108 functions to scrape off the toner T adhering to the collection roller 106.

  Each of the above components from the cleaning roller 105 to the storage box 107 is housed in a housing 109. The housing 109 is configured to be movable up and down by a belt cleaner separation solenoid 110 as an example of a second solenoid. ing. For this reason, when the belt cleaner separating solenoid 110 is contracted to raise the casing 109, the cleaning roller 105 comes into contact with the paper transport belt 6, and when the belt cleaner separating solenoid 110 is extended to lower the casing 109, the cleaning is performed. The roller 105 is isolated from the paper transport belt 6.

  Returning to FIG. 1, the transfer roller 61 has a transfer bias (for example, −10 to −15 μA) opposite in polarity to the charging polarity of the toner T between the transfer roller 61 and the photosensitive drum 3 by the negative voltage current source 112. The toner image formed on the photosensitive drum 3 when applied is transferred to the paper P conveyed by the paper conveying belt 6.

  The fixing device 8 includes a heating roller 81 and a pressure roller 82, and heats and presses the sheet P on which the toner image is transferred while nipping and conveying the sheet P by the heating roller 81 and the pressure roller 82. Thus, the toner image is fixed on the paper P.

  A stacker 12 is formed on the upper surface of the printer 1. The stacker 12 is provided on the paper discharge side of the fixing device 8 and accommodates the paper P discharged from the fixing device 8. The control unit 10 is configured by a control device using a well-known ASIC (Application Specific Integrated Circuit) 200 (see FIG. 3) as described later, and controls the overall operation of the printer 1.

  By the way, the four photosensitive drums 3 are all provided so that the photosensitive drum 3 can be moved in the upward direction away from the paper transport belt 6 and straddles the four photosensitive drums 3. It is positioned by a moving member 72 as a separating means. The moving member 72 is configured by a plate-like member having a length straddling the four photosensitive drums 3, and is held so as to be movable in the left-right direction in FIG. The moving member 72 is provided with four substantially crank-shaped guide holes 72A extending in the left-right direction, and shafts 3A provided on the side surfaces in the longitudinal direction of the respective photosensitive drums 3 in the guide holes 72A. Is inserted.

  The moving member 72 is provided with a lift motor 74 via a link 73 that changes the rotational force into a lateral force, and the lift motor 74 rotates in response to a command signal from the control unit 10. The moving member 72 moves rightward or leftward. Thus, when the moving member 72 moves to the left, when the guide hole 72A moves to the left, the shaft 3A of each photosensitive drum 3 moves upward along the substantially crank shape of the guide hole 72A. For this reason, the photosensitive drum 3 is separated from the paper transport belt 6. On the other hand, when the moving member 72 is at the right position, the photosensitive drum 3 comes into contact with the paper transport belt 6. Normally, image formation is performed with the photosensitive drum 3 in contact with the paper transport belt 6.

  The image forming operation on the paper P in the printer 1 according to the present embodiment having the above-described configuration is as follows. First, a sheet of paper P is supplied from the paper supply unit 9 by the paper supply roller 92 and is sent to the paper transport belt 6 via the transport roller 98 and the registration roller 99. Next, the surface of the rightmost photosensitive drum 3 </ b> Y in FIG. 1 is uniformly charged by the charger 31 and exposed by the scanner unit 41 corresponding to the image data input from the outside for yellow color. Thus, an electrostatic latent image is formed as described above. Next, yellow toner T charged to positive polarity in the developing unit 51Y is supplied to the surface of the photosensitive drum 3Y, and development is performed. The toner image formed in this way is transferred onto the surface of the paper P conveyed by the paper conveying belt 6 by a transfer roller 61 to which a transfer bias is applied.

  Next, the paper P is sequentially conveyed to a position facing the photoconductor drums 3 for magenta, cyan, and black, and the toner image is formed on the surface of the photoconductor drum 3 in the same procedure as the yellow toner T. The sheet is formed and transferred onto the paper P by the transfer roller 61. Finally, the four color toner images formed on the paper P are fixed on the paper P in the fixing device 8 and discharged onto the stacker 12.

  Next, FIG. 3 is a block diagram showing the configuration of the control system of the printer 1. As shown in FIG. 3, the control unit 10 is configured with an ASIC 200, a composite IC 210 as an example of a first IC, and a composite IC 220 as an example of a second IC. The ASIC 200 includes a CPU and executes various processes based on a software program, but detailed description thereof is omitted.

  The printer 1 includes a first fan 251 and a second fan 253 for cooling the internal mechanism, but a first fan drive as an example of a fan motor that drives the first fan 251 as an example of a fan. The motor 255 is connected to the composite IC 210, and the second fan drive motor 257 that drives the second fan 253 is connected to the composite IC 220. The composite IC 210 is connected to a belt drive motor 261 as an example of a motor that drives the paper transport belt 6 via the drive roller 62 and a polygon motor 265 that drives the polygon mirror. A fixing & belt cleaner motor 267 for driving the above-described fixing device 8 and the like, and a developing driving motor 269 for driving the above-described developing roller 52 and the like are connected to the above.

  Here, the driving force of the fixing & belt cleaner motor 267 is constantly transmitted to the heating roller 81 and the pressure roller 82 of the fixing device 8, but the paper feeding roller 92, the registration roller 99, and the cleaning roller 105 of the belt cleaner 100. For example, the transmission / non-transmission of the driving force can be switched. That is, as schematically shown in FIG. 4, there are a feeding solenoid 271, a registration solenoid 273, and a driving force transmission path from the fixing & belt cleaner motor 267 to the feeding roller 92, the registration roller 99, or the belt cleaner 100. A belt cleaner stop solenoid 275 is provided in the form of a known electromagnetic clutch or the like.

  Therefore, as shown in FIG. 3, the paper feed solenoid 271 and the registration solenoid 273 are connected to the composite IC 210, and the belt cleaner stop solenoid 275 and the belt cleaner separation solenoid 110 (see FIG. 2) are connected to the composite IC 220, respectively. ing.

  Next, the composite IC 210 includes a driver circuit 211 as an example of fan drive means for driving the first fan drive motor 255, and a first motor as an example of motor drive means for driving the belt drive motor 261 and the polygon motor 265. Driver circuit timer circuit 213, 214 as an example of a first solenoid driving means and a timing control means for driving a feed solenoid 271 and a registration solenoid 273 as an example of a first solenoid, and an AND circuit, respectively 215 to 218 are provided.

  The composite IC 220 includes a driver circuit 221 that drives the second fan drive motor 257, a second motor driver 222 as an example of a cleaning motor drive unit that drives the fixing & belt cleaner motor 267 and the development drive motor 269, Driver circuit timer circuits 223 and 224 for driving the belt cleaner stop solenoid 275, the belt cleaner separation solenoid 110, and AND circuits 225 to 228, respectively, are provided.

  Next, signals input / output at each unit will be described. The ASIC 200 inputs the first fan ON signal and the second fan ON signal to the driver circuits 211 and 221 respectively, and the driver circuits 211 and 221 receive the first fan drive motor 255 and the second fan drive motor in response to the signals. A drive signal is output to 257. Further, the composite ICs 210 and 220 mutually input their own overcurrent detection and thermal shutdown information as alarms, and the alarms input from the composite IC 220 to the composite IC 210 are inverted and input to the AND circuit 215. Yes. The first fan ON signal described above is also input to the AND circuit 215, and the result of the logical product operation is input to the AND circuit 216. In addition to the output of the AND circuit 215, the belt drive motor 261 and the motor drive permission (Enable) to the polygon motor 265 input from the ASIC 200 are also input to the AND circuit 216, and the result of the logical product operation is the first motor driver 212. Is input.

  That is, the motor drive permission is invalidated except when the alarm is not generated in the composite IC 220 and the first fan ON signal is output. In addition, the first motor driver 212 receives a speed control signal of the belt drive motor 261, a rotation direction selection signal, and a speed control signal of the polygon motor 265 from the ASIC 200. Conversely, a signal for feeding back the speeds of the belt drive motor 261 and the polygon motor 265 is input from the first motor driver 212 to the ASIC 200. Only when the motor drive permission is input to the first motor driver 212, the belt drive motor 261 to which the speed control signal and the belt drive motor rotation direction selection signal are input or the speed control signal is input. The polygon motor 265 is driven based on the input signals and the like.

  Also, a belt drive motor output as a drive signal is input from the first motor driver 212 to the belt drive motor 261, and a signal for feeding back the speed of the belt drive motor 261 from the belt drive motor 261 to the first motor driver 212. , And a signal for feeding back the speed and position of the belt drive motor 261 is input. Similarly, a polygon motor output as a drive signal is input from the first motor driver 212 to the polygon motor 265, and a signal for feeding back the speed and position of the polygon motor 265 is transmitted from the polygon motor 265 to the first motor driver 212. Have been entered.

  The first motor driver 212 also includes a belt drive motor overcurrent detection circuit 212A as an example of an overcurrent detection unit that detects an overcurrent of the belt drive motor 261. The detection result is sent to the driver circuit 211 described above. Is also entered. Therefore, it is possible to control the first fan 251 to stop when an overcurrent is applied to the belt drive motor 261. The first motor driver 212 stops the belt drive motor 261 and the polygon motor 265 when the belt drive motor overcurrent detection circuit 212A detects an overcurrent.

  Further, the output of the AND circuit 216 is input to the AND circuit 217 together with the feed solenoid ON signal from the ASIC 200 and the negation of the overcurrent detection result of the belt drive motor 261, and the result of the logical product operation is the driver circuit timer circuit. 213 is input. In other words, the driver circuit timer circuit 213 receives permission to drive the belt drive motor 261 and the polygon motor 265 to the first motor driver 212, the overcurrent of the belt drive motor 261 is not detected, and is supplied from the ASIC 200. Only when the paper solenoid ON signal is input, the power supply solenoid 271 is energized. The driver circuit timer circuit 213 includes a timer circuit that counts the energization time to the paper feed solenoid 271 and forcibly stops energization when the energization time exceeds a predetermined time.

  Similarly, the driver circuit timer circuit 214 inputs the AND operation result of the AND circuit 216, the registration solenoid ON signal from the ASIC 200, and the negation of the overcurrent detection result of the belt drive motor 261 via the AND circuit 218. The drive permission to the belt drive motor 261 and the polygon motor 265 is input to the first motor driver 212, the overcurrent of the belt drive motor 261 is not detected, and the registration solenoid ON signal is input from the ASIC 200. Only when the registration solenoid 273 is energized. The driver circuit timer circuit 214 also includes a timer circuit that counts the energization time to the registration solenoid 273, and forcibly stops energization when the energization time exceeds a predetermined time.

  Next, as described above, the alarm is also input from the composite IC 210 to the composite IC 220, and this alarm is inverted and input to the AND circuit 225. The above-described second fan ON signal is also input to the AND circuit 225, and the result of the logical product operation is input to the AND circuit 226. In addition to the output of the AND circuit 225, the AND circuit 226 also receives a motor driving permission (Enable) from the ASIC 200 to the fixing & belt cleaner motor 267 and the developing drive motor 269, and the result of the logical product operation is the second motor driver. 222 is input.

  That is, the motor drive permission to the fixing & belt cleaner motor 267 and the development drive motor 269 is invalidated except when no alarm is generated in the composite IC 210 and the second fan ON signal is output. . In addition, the speed control signal and rotation direction selection signal of the fixing & belt cleaner motor 267 and the speed control signal and rotation direction selection signal of the development drive motor 269 are input from the ASIC 200 to the second motor driver 222. On the other hand, a signal for feeding back the speeds of the fixing & belt cleaner motor 267 and the developing drive motor 269 is input from the second motor driver 222 to the ASIC 200. Only when the motor drive permission is input to the second motor driver 222, the fixing & belt cleaner motor 267 or the development drive motor 269 to which the speed control signal and the rotation direction selection signal are input are used as those signals. Driven based on.

  Further, a fixing & belt cleaner motor output as a drive signal is input from the second motor driver 222 to the fixing & belt cleaner motor 267, and the fixing & belt cleaner motor 267 is input from the fixing & belt cleaner motor 267 to the second motor driver 222. A signal for feeding back the speed of the motor 267 and a signal for feeding back the speed and position of the fixing and belt cleaner motor 267 are inputted. Similarly, a development drive motor output as a drive signal is input from the second motor driver 222 to the development drive motor 269, and the speed of the development drive motor 269 is fed back from the development drive motor 269 to the second motor driver 222. A signal and a signal for feeding back the speed and position of the development drive motor 269 are input.

  The second motor driver 222 also includes a fixing & belt cleaner motor overcurrent detection circuit 222A that detects an overcurrent of the fixing & belt cleaner motor 267, and the detection result is also input to the driver circuit 221 described above. Yes. Therefore, it is possible to control the second fan 253 to stop when an overcurrent is supplied to the fixing & belt cleaner motor 267. The second motor driver 222 stops the fixing & belt cleaner motor 267 and the developing drive motor 269 when the fixing & belt cleaner motor overcurrent detection circuit 222A detects an overcurrent.

  Further, the output of the AND circuit 226 is input to the AND circuit 227 together with the belt cleaner stop solenoid ON signal from the ASIC 200 and the negative result of the overcurrent detection result of the fixing & belt cleaner motor 267, and the result of the logical product operation is input to the driver. Input to the circuit timer circuit 223. That is, in the driver circuit timer circuit 223, driving permission to the fixing & belt cleaner motor 267 and the developing drive motor 269 is input to the second motor driver 222, and no overcurrent of the fixing & belt cleaner motor 267 is detected. In addition, the belt cleaner stop solenoid 275 is energized only when the belt cleaner stop solenoid ON signal is input from the ASIC 200. The driver circuit timer circuit 223 includes a timer circuit that counts the energization time to the belt cleaner stop solenoid 275, and forcibly stops energization when the energization time exceeds a predetermined time.

  Similarly, the driver circuit timer circuit 224 as an example of the second solenoid driving unit similarly negates the output of the AND circuit 226, the belt cleaner separation solenoid ON signal from the ASIC 200, and the overcurrent detection result of the fixing & belt cleaner motor 267. AND operation result is input via the AND circuit 228. For this reason, the driver circuit timer circuit 224 receives permission to drive the fixing & belt cleaner motor 267 and the developing drive motor 269 to the second motor driver 222, and the overcurrent of the fixing & belt cleaner motor 267 is not detected. Only when the belt cleaner separating solenoid ON signal is input from the ASIC 200, the belt cleaner separating solenoid 110 is energized. The driver circuit timer circuit 224 also includes a timer circuit that counts the energization time to the belt cleaner separation solenoid 110, and forcibly stops energization when the energization time exceeds a predetermined time.

  As described above, in the present embodiment, no alarm is generated in the composite IC 220, an overcurrent of the fixing & belt cleaner motor 267 is not detected, and the first fan ON signal is output. On this condition, driving of the belt driving motor 261 and the polygon motor 265 is allowed (see AND circuits 215 and 216). Also, the fixing & belt cleaner motor 267 is provided on condition that no alarm is generated in the composite IC 210, the overcurrent of the belt drive motor 261 is not detected, and the second fan ON signal is output. Is allowed (see AND circuits 225 and 226). In addition to the AND circuits 215, 216, 225, and 226, the first motor driver 212 and the second motor driver 222 are also composed of hard logic circuits as is well known.

  For this reason, in the present embodiment, the belt drive motor 261, the polygon motor 265, the fixing & belt cleaner motor 267, and the development drive motor 269 are provided even though the first fan 251 or the second fan 253 is not driven. If the motor (261, 265 or 267, 269) or the composite IC 210 or 220 is overheated by being driven, even if the CPU runs out of control, it is surely suppressed without being affected by the runaway. it can. Moreover, in the present embodiment, when the belt drive motor overcurrent detection circuit 212A or the fixing & belt cleaner motor overcurrent detection circuit 222A detects an overcurrent, the first fan drive motor 255, the belt drive motor 261, and the polygon motor 265 are detected. Since the second fan drive motor 257, the fixing & belt cleaner motor 267, and the development drive motor 269 are all stopped, the motor (255 to 269) is energized and the CPU runs out of control. Can be reliably suppressed without being affected by the runaway.

  Further, in the present embodiment, the driving of the sheet feeding solenoid 271 and the registration solenoid 273 is permitted on the condition that the driving of the belt driving motor 261 and the polygon motor 265 is permitted (see AND circuits 217 and 218), and the fixing. & The belt cleaner stop solenoid 275 and the belt cleaner separation solenoid 110 are allowed to be driven on condition that the driving of the belt cleaner motor 267 and the developing drive motor 269 is permitted (see AND circuits 227 and 228). In addition to the AND circuits 217, 218, 227, and 228, the driver circuit timer circuits 213, 214, 223, and 224 are also composed of hard logic circuits. Therefore, in this embodiment, unnecessary operations of the solenoids 271, 273, 275, and 110 can be reliably suppressed without being affected by the runaway even if the CPU runs away.

  Moreover, in the present embodiment, the driver circuit 211, the first motor driver 212, the driver circuit timer circuits 213 and 214, and the AND circuits 215, 216, 217, and 218 are formed in a common composite IC 210, and the driver circuit 221 The second motor driver 222, driver circuit timer circuits 223 and 224, and AND circuits 225, 226, 227, and 228 are formed in a common composite IC 220. For this reason, the configuration can be simplified to reduce the manufacturing cost, and malfunction due to noise or the like can be suppressed. In other words, when these circuits are formed in separate ICs, not only the configuration becomes complicated, but also noise may be superimposed on the signal lines that connect the ICs. Can be prevented. Furthermore, since the composite ICs 210 and 220 have substantially the same configuration as described above, the parts can be shared and the manufacturing cost of the control unit 10 can be reduced well.

  In the above embodiment, the configuration related to the control when the AND circuit 216 and the first motor driver 212 detect overcurrent is the first safety control means, and the AND circuits 217 and 218 are the second safety control means. The AND circuit 225 corresponds to a third safety control unit. Further, the present invention is not limited to the above-described embodiment, and can be implemented in various forms without departing from the gist of the present invention. For example, the present invention can be applied to a monochrome laser printer, an electrophotographic copying machine, a facsimile machine, and the like.

  FIG. 5 is a block diagram showing the configuration of a control system when the present invention is applied to a monochrome laser printer. As shown in FIG. 5, the control system is configured with an ASIC 300 and a composite IC 310 as an example of the first IC as a center.

  The laser printer of this embodiment also includes a fan 351 as an example of a fan for cooling the internal mechanism, and a fan drive motor 355 as an example of a fan motor that drives the fan 351 is connected to the composite IC 310. Has been. The composite IC 310 includes a main motor 361 as an example of a motor that drives a conveying unit such as a paper feed roller and a registration roller of the laser printer and an image forming unit such as a photosensitive drum and a developing roller (all not shown). And a polygon motor 365 for driving the polygon mirror is connected. Further, a sheet feeding solenoid 371 and a registration solenoid 373 as examples of a first solenoid for switching whether to transmit the driving force of the main motor 361 to the sheet feeding roller and the registration roller are also connected to the composite IC 310.

  Next, the composite IC 310 includes a driver circuit 311 as an example of fan driving means for driving the fan driving motor 355, a motor driver 312 as an example of motor driving means for driving the main motor 361 and the polygon motor 365, and a power supply. Driver circuit timer circuits 313 and 314 as examples of first solenoid driving means and timing control means for driving the paper solenoid 371 and the registration solenoid 373, and AND circuits 316 to 318 are provided.

  Next, signals input / output at each unit will be described. The ASIC 300 inputs a fan ON signal to the driver circuit 311, and in response to the signal, the driver circuit 311 outputs a drive signal to the fan drive motor 355.

  The fan ON signal is input to the AND circuit 316 together with the motor drive permission (Enable) to the main motor 361 and the polygon motor 365 input from the ASIC 300, and the result of the logical product operation is input to the motor driver 312. . That is, the motor drive permission is invalidated except when a fan ON signal is output from the ASIC 300. In addition, the motor driver 312 receives a speed control signal for the main motor 361, a rotation direction selection signal, and a speed control signal for the polygon motor 365 from the ASIC 300. Conversely, a signal for feeding back the speeds of the main motor 361 and the polygon motor 365 is input from the motor driver 312 to the ASIC 300.

  Further, a main motor output as a drive signal is input from the motor driver 312 to the main motor 361, and a signal for feeding back the speed of the main motor 361 and the speed of the main motor 361 from the main motor 361 to the motor driver 312. And a signal for feedback of the position is input. Similarly, a polygon motor output as a drive signal is input from the motor driver 312 to the polygon motor 365, and a signal that feeds back the speed and position of the polygon motor 365 is input from the polygon motor 365 to the motor driver 312. .

  The motor driver 312 also includes a main motor overcurrent detection circuit 312A as an example of overcurrent detection means for detecting an overcurrent of the main motor 361. The detection result is also input to the driver circuit 311 described above. Yes. For this reason, it is possible to control the fan 351 to stop when an overcurrent is supplied to the main motor 361. The motor driver 312 stops the main motor 361 and the polygon motor 365 when the main motor overcurrent detection circuit 312A detects an overcurrent.

  Further, the output of the AND circuit 316 is input to the AND circuit 317 together with the feed solenoid ON signal from the ASIC 300 and the negation of the overcurrent detection result of the main motor 361, and the result of the logical product operation is the driver circuit timer circuit 313. Is input. That is, the driver circuit timer circuit 313 receives the permission to drive the main motor 361 and the polygon motor 365 to the motor driver 312, the overcurrent of the main motor 361 is not detected, and the ASIC 300 supplies a paper feed solenoid ON signal. Only when the “” is input, the paper feed solenoid 371 is energized. The driver circuit timer circuit 313 includes a timer circuit that counts the energization time to the paper feed solenoid 371, and forcibly stops energization when the energization time exceeds a predetermined time.

  Similarly, the driver circuit timer circuit 314 receives the AND operation result of the output of the AND circuit 316, the registration solenoid ON signal from the ASIC 300, and the negation of the overcurrent detection result of the main motor 361 via the AND circuit 318. Only when the permission to drive the main motor 361 and the polygon motor 365 is input to the motor driver 312, the overcurrent of the main motor 361 is not detected, and the registration solenoid ON signal is input from the ASIC 300, Energization of the registration solenoid 373 is performed. The driver circuit timer circuit 314 also includes a timer circuit that counts the energization time to the registration solenoid 373, and forcibly stops energization when the energization time exceeds a predetermined time.

  For this reason, even in the present embodiment, the main motor 361, the polygon motor 365 and the composite IC 310 may be overheated when the main motor 361 and the polygon motor 365 are driven even though the fan 351 is not driven. Even if the CPU runs out of control, it can be reliably suppressed without being affected by the runaway. Also in this embodiment, since the main motor 361 and the polygon motor 365 are stopped when the main motor overcurrent detection circuit 312A detects an overcurrent, it is unlikely that the overcurrent will be supplied to the main motor 361. Even if runaway occurs, it can be reliably suppressed without being affected by the runaway.

  Further, in the present embodiment, the driving of the sheet feeding solenoid 371 and the registration solenoid 373 is permitted on the condition that the driving of the main motor 361 and the polygon motor 365 is permitted. Therefore, those solenoids (371, 373) are permitted. Even if the CPU runs out of control, the unnecessary operation can be reliably suppressed without being affected by the runaway. In addition, in the present embodiment, the driver circuit 311, the motor driver 312, the driver circuit timer circuits 313 and 314, and the AND circuits 316 to 318 are formed in the common composite IC 310. In addition, it is possible to suppress malfunction due to noise or the like. Further, since the composite IC 310 has substantially the same configuration as the above-described composite ICs 210 and 220, the monochrome laser printer of the present embodiment and the above-described color laser printer 1 can share parts, and the manufacturing cost can be reduced well. can do.

  Furthermore, in each of the above embodiments, the various fans 251, 252, and 351 are stopped when an overcurrent is detected. However, in order to cool the circuit, it may be stopped after being driven for a predetermined time.

It is a schematic sectional drawing showing the internal structure of the color laser printer to which this invention is applied. It is explanatory drawing showing the structure of the belt cleaner of the printer in detail. It is a block diagram showing the structure of the control system of the printer. FIG. 3 is a block diagram schematically illustrating a part of a driving force transmission path of the printer. It is a block diagram showing the structure of the control system of the monochrome laser printer to which this invention is applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Color laser printer 4 ... Toner image formation part 6 ... Paper conveyance belt 10 ... Control part 92 ... Paper feed roller 99 ... Registration roller 100 ... Belt cleaner 105 ... Cleaning roller 110 ... Belt cleaner separation solenoid 210, 220, 310 ... Composite IC
211, 221, 311 ... driver circuit 212 ... first motor driver 212A ... belt drive motor overcurrent detection circuit 213, 214, 223, 224, 313, 314 ... driver circuit timer circuits 215, 216, 217, 218, 225, 226 , 227, 228, 316, 317, 318, ... AND circuit 222 ... motor driver 222 ... second motor driver 222A ... belt cleaner motor overcurrent detection circuit 251 ... first fan 253 ... second fan 255 ... first fan drive motor 257 ... second fan drive motor 261 ... belt drive motor 267 ... fixing & belt cleaner motor 271 ... feed solenoid 273 ... registration solenoid 275 ... belt cleaner stop solenoid 312 ... motor driver 312A ... main motor overcurrent detection circuit 35 ... fan 355 ... fan drive motor 361 ... the main motor 365 ... polygon motor 371 ... feeding solenoid 373 ... registration solenoid

Claims (7)

Image forming means for forming an image on a recording medium by an electrophotographic method;
Conveying means for conveying a recording medium through the image forming means;
An image forming apparatus comprising:
A motor provided inside the image forming apparatus and driving an internal mechanism of the image forming apparatus;
Motor driving means for driving the motor;
Fan driving means for driving a fan motor for driving a fan for cooling the inside of the image forming apparatus;
First safety control means for allowing the motor to be driven on condition that the fan motor is driven;
With
An image forming apparatus, wherein the motor driving means, the fan motor driving means, and the first safety control means are formed in a common first IC. Overcurrent detection means formed in the first IC for detecting the overcurrent of the motor,
In addition,
The image forming apparatus according to claim 1, wherein the first safety control unit stops driving of the motor when the overcurrent detection unit detects an overcurrent.   3. The image forming apparatus according to claim 1, wherein the first safety control means is constituted by a hard logic circuit. The motor drives at least the conveying means;
A first solenoid for switching transmission / non-transmission of the driving force of the motor to the recording medium;
First solenoid driving means formed in the first IC for driving the first solenoid;
Second safety control means formed in the first IC and permitting the driving of the first solenoid on the condition that the driving of the motor is permitted;
The image forming apparatus according to claim 1, further comprising:   The image forming apparatus according to claim 4, wherein the second safety control circuit is configured by a hard logic circuit.   6. The image forming apparatus according to claim 4, wherein a timing control means for measuring the time and controlling the first solenoid on the basis of the timing result is formed in the first IC. A cleaning motor for driving the cleaning mechanism of the conveying means;
Cleaning motor driving means for driving the cleaning motor;
A second solenoid for switching contact and separation of the cleaning mechanism to and from the transport means;
Second solenoid driving means for driving the second solenoid;
Third safety control means for permitting driving of the cleaning motor and the second solenoid on condition that the motor driving means formed in the first IC is operating normally;
With
7. The cleaning motor driving means, the second solenoid driving means, and the third safety control means are formed in a common second IC. Image forming apparatus.

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