JP2006317634A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device equipped with a fixing part of a heat fixing method capable of correcting the fixing roller heating time in correspondence with types of paper, pixel density, etc. and also correcting the current applied to the fixing part without using a complicated and expensive control means. <P>SOLUTION: When the temperature of the fixing part is below the lower limit of the fixing temperature (Step S403/YES) in the image forming device equipped with a fixing part of a heat fixing method, the image forming operation is interrupted (Step S404). After the heating time is corrected (Step S406) in correspondence with the detected type of paper, etc. (Step S405), heating of the fixing part is implemented for the time as corrected, and then the image forming operations is resumed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus having a heat fixing type fixing unit, such as a laser printer, a copying machine, and a multifunction peripheral.

  2. Description of the Related Art Conventionally, in image forming apparatuses such as laser printers and copiers, a heat roll type in which a heating device such as a halogen heater or an induction coil is installed in or near a cylindrical fixing roller and the fixing roller is heated by the heat source. A fixing device is often used. In this method, an element (sensor) for temperature detection is arranged in the vicinity of or in contact with the fixing roller, and in the case of a heater, the heater driving element is turned on / off to stabilize the temperature of the fixing roller surface. Control is in progress. In the case of the induction heating method, the current applied to the inverter is detected and then the current applied to the coil is adjusted so that the temperature on the surface of the fixing roller is stabilized. This is because the heat of the fixing roller is taken away by the paper during the fixing operation, and the temperature of the fixing roller may continue to decrease when continuous fixing is performed. In recent years, the number of image forming apparatuses equipped with an automatic document feeder (ADF) has increased. When image forming processing is performed using such an ADF, continuous fixing exceeding the predetermined number of sheets in the apparatus main body becomes possible, and the fixing possible temperature The temperature of the fixing roller may drop below. Particularly, recently, with the increase in the speed of image forming processing, the amount of heat removed per unit of time during the fixing operation increases, and this tendency is increasing. .

  As a method of avoiding such a situation and preventing the temperature of the fixing roller from lowering, a method of increasing the power supplied to the heater of the fixing roller and a heat capacity of the fixing roller that plays a cushioning role by taking thermal equilibrium with the heater There is a way to make it bigger. However, the former is difficult because there is a request to reduce the rated current described later and the rated current of the device cannot be easily increased. In the latter case, the fixing roller itself is reduced in size in response to the downsizing of the entire apparatus. This is contrary to the current decrease in the heat capacity of the fixing roller. Even when a small number of images are formed, the power consumption is higher, resulting in higher costs.

  In order to solve this problem, Japanese Patent Application Laid-Open No. H10-228667 proposes a means for changing the speed of the image forming process after detecting the surface temperature of the fixing roller. Further, in Patent Document 2, the machine operation is stopped when the temperature is lower than the lower limit fixing temperature, and the fixing heating is performed until the necessary amount of heat is obtained for the remaining number of copies. When the predetermined temperature is reached, copying is resumed. Means to do this have been proposed.

On the other hand, while the power consumption of the drive system is increasing with the colorization and speeding up of image forming devices in recent years, there are demands for energy saving and rated current reduction from the market. It is a situation that is difficult to raise easily. For this reason, the current that can be used in the fixing device is limited, and the electric power in the fixing device may be insufficient depending on the operating state of each device. In particular, multi-function peripherals with many peripheral devices have various system combinations. If a plurality of peripheral devices are installed, input current increases and problems are likely to occur.
Japanese Patent Laid-Open No. 61-18983 JP-A-7-140833

  However, the above invention has the following problems.

  The invention described in Patent Document 1 is intended to reduce the image forming processing speed when the temperature of the fixing roller is low. However, in the case of such means that makes the process speed variable, stable image forming conditions can be obtained. The control system parts are complicated and expensive.

  In the invention described in Patent Document 2, the machine operation is stopped when the fixing roller falls below the lower limit fixing temperature, and the machine operation is stopped when the temperature rise corresponding to the amount of heat necessary for the remaining number of copies is detected by the fixing roller. Although the control is performed so as to resume, the amount of heat required for copying varies depending on various conditions such as the type of transfer paper and the amount of toner attached, and it is difficult to perform these calculation processes during operation.

  Therefore, the present invention controls to interrupt the image forming operation such as exposure and development operations for a predetermined time set according to the remaining number of copies, heat the fixing roller, and then restart the image forming operation. Accordingly, it is an object of the present invention to improve the efficiency of copying work by eliminating abnormal images and shortening the copying time without performing complicated arithmetic processing.

  In addition, since the amount of heat required for copying varies depending on various conditions, it is difficult to calculate the heating time (operation interruption time), so that the paper type of the transfer paper, the image density, the input voltage to the fixing device, etc. The purpose is to optimize the interruption time by correcting the interruption time based on the above, and to improve the efficiency of the copying operation.

  In response to avoiding a decrease in temperature rise efficiency of the fixing unit due to power shortage in the fixing device, the power supply to the fixing heater is maximized based on the setup state and operating state of the system. The purpose is to improve the efficiency of copying operations.

  According to a first aspect of the present invention, in an image forming apparatus including a heat fixing type fixing unit, a heating unit that heats the fixing unit, a temperature detection unit that detects a temperature of the fixing unit, and a detection by the temperature detection unit. Control means for suspending exposure and development operations when the temperature of the fixed fixing section is lower than the lower limit fixing temperature and restarting the exposure and development operations after heating the fixing section for a predetermined time by the heating means; It is characterized by having.

  According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the control unit changes a heating time of the fixing unit by the heating unit in accordance with a paper type of the transfer paper being passed. It is characterized by.

  According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, the control unit changes a heating time of the fixing unit by the heating unit in accordance with a pixel density or the like of an image being formed. It is characterized by doing.

  According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, the control unit applies the heating unit to the fixing unit in accordance with an input voltage to the fixing unit. The heating time is changed.

  According to a fifth aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects, the control means uses the heating means with the maximum power that can be input in accordance with the current consumption of each mechanism. The fixing unit is heated.

  By controlling to stop the image forming operation for a set time according to the remaining number of copies, heat the fixing roller, and then restart the image forming operation, an abnormal operation can be performed without performing complicated arithmetic processing. By reducing the number of images and shortening the copy time, it is possible to improve the user's copy operation efficiency.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows the configuration of the fixing unit according to this embodiment. The fixing roller 1 includes a main heater 2 and a sub-heater 3 that are two heaters, and each heater is connected to an AC power source by control drivers 4 and 5. The control drivers 4 and 5 are on / off controlled by the CPU 8. When the control drivers 4 and 5 are on, the heater is connected to the power source and generates heat. In general, a main heater having a large calorific value is arranged closer to the portion through which the transfer paper is passed. When the sub-heater is installed to shorten the rise time, it is used when changing the light distribution of the main heater as a measure against the temperature rise at the end, and when a heating element is mainly arranged at the roller end. Thermistor elements 6 and 7 for temperature detection are installed on the surface of the fixing roller 1, and the CPU 8 determines the surface temperature of the fixing roller 1, and the two heaters are turned on / off so that the surface temperature becomes a constant value. Made.

  In this device, the CPU 8 or other CPU in the device grasps the state of system up and the necessary input current of each device, and limits the input current to the heater by turning the driver off or switching depending on the mode. It can be carried out.

  In recent years, there is a device that uses a ceramic heater instead of a halogen heater, and there is also a device in which an induction coil is installed in or near a roller, and current is supplied to the coil via an inverter to control heating of the fixing device. Even in the case of the induction heating method, it is possible to limit the input current to the fixing device by detecting the input or output current of the inverter.

  FIG. 2 is a block diagram illustrating a configuration of the digital multifunction peripheral according to the present embodiment. The control of the composite main body includes an operation unit controller 502 that controls the liquid crystal display and LED display 501 and various key inputs 500, a main controller 503 that controls sheet feeding, conveyance, fixing, and process, and image reading control. A scanner controller 504, an ADF controller 505 that performs ADF control according to a signal from the scanner controller 504, a sorter controller 506 that controls a sorter, a printing unit 507 that feeds / conveys transfer paper and forms an image according to instructions from the main controller, A FAX controller 509 that performs FAX transmission / reception management and file management, a G3 controller 510 that performs G3 protocol control, a G4 controller 511 that performs G4 protocol control, a memory device 512 that stores files, a personal computer, etc. A printer controller 513 for receiving a lint command, a heater A518, a fixing unit 514 for controlling the heater B519, a power supply device 515 for supplying power to the main controller and peripheral devices, and a current detection element for detecting an input current to the device 516, a bypass element 517 for bypassing the current detection element 516, and the like.

  At the time of FAX reception / printing, the data sent from the line is sent to the FAX controller 509 via the G3 controller 510 or G4 controller 511. The data stored in the FAX controller 509 is transferred to the main controller 503, subjected to image processing, and then sent to write control for printing.

  When a print command is received from a personal computer or the like, print data sent from the personal computer or the like is transferred to the main controller 503 via the printer controller 513 and subjected to image processing, and then sent to write control for printing.

  FIG. 3 is a control flow of one embodiment of the present invention. During continuous copying or printing, the temperature of the fixing roller is monitored. Subsequently, heat treatment is performed until the temperature rises corresponding to the amount of heat necessary to copy the number of sheets remaining after the image forming operation is interrupted. Then, after a predetermined set time has elapsed, the image forming operation is resumed.

  First, continuous copying starts through continuous sheet feeding control (step S301). If the temperature of the fixing roller reaches a lower limit value that can guarantee an image without completing copying (step S302 / NO), the image forming operation is interrupted (step S304). If the continuous copying is completed (step S302 / YES), a start state is entered (step S307), and if the temperature of the fixing roller does not reach the lower limit value (step S303 / NO), the copying is continued (step S308). Next, after the image forming operation is interrupted (step S304), the fixing roller enters a heating mode and is heated by the heater for a predetermined time. Then, when the set time of the heating mode has elapsed (step S305 / YES) and the temperature of the fixing roller reaches a temperature corresponding to the amount of heat necessary for copying the remaining number of sheets, the image forming operation is resumed (step S306). ) The remaining number of copies is copied. When the set time of the heating mode does not elapse (step S305 / NO), the fixing roller is heated up to the set time while the image forming operation is interrupted.

  However, when the temperature of the fixing roller reaches the temperature at the start of copying during the heating mode, the image forming operation is resumed even within the set time of the heating mode.

  Regarding the interruption of the image forming operation, if the transfer paper during the image forming process stops halfway, it is very difficult to resume from the same operation, causing an error. It is desirable to interrupt after the process is completed. At that time, in order to prevent occurrence of abnormal images such as fixing failure, it is preferable to set the determination temperature of the lower limit of fixing slightly higher than the actual lower limit.

  Calculation of the amount of heat required for the remaining number of copies will be described. A correlation between the temperature drop of the surface temperature of the fixing roller and the number of fixed sheets is stored in advance in, for example, a memory unit in the main controller 501. Thereby, the temperature drop of the unit number of sheets and the amount of heat lost can be calculated. Similarly, the correlation between the heating time and the rise in surface temperature is also stored in advance in the memory unit. Thereby, the temperature rise per unit time and the amount of heat to be applied can be calculated. The amount of heat required for copying the remaining number is obtained by multiplying the amount of heat deprived of the unit number by the remaining number. The remaining number of sheets is calculated by detecting the number of sheets on which image forming processing has been performed by a sensor in the main controller 501, for example.

  FIG. 4 is a control flow of another embodiment of the present invention. As described above, during continuous copying or printing, the temperature of the fixing roller is monitored, and the image forming process is interrupted when the temperature reaches a lower limit value that can guarantee the image. Based on the paper type, pixel density, image density, input voltage to the fixing unit, or the maximum power that can be applied to the fixing unit calculated from the current consumption of each mechanism, The current to the heater is corrected, and the image forming operation is resumed after the corrected heating mode setting time elapses.

  First, continuous copying starts through continuous sheet feeding control (step S401), and copying is not completed (step S402 / NO). When the temperature of the fixing roller reaches a lower limit value that can guarantee an image (step S403 / YES), an image forming operation is performed. Is interrupted (step S404). If the continuous copying is completed (step S402 / YES), a start state is entered (step S409), and if the temperature of the fixing roller does not reach the lower limit value (step S403 / NO), the copying is continued (step S410). Next, as will be described later, the paper, pixel density, and image density are confirmed by the sensor (step S405), and the heating time is corrected in accordance with these (step S406). Heated by. In the case of the input voltage, the input voltage to the fixing device is confirmed by a sensor (step S405), and the heating time is corrected according to the input voltage (step S406). Heated. Further, in the case of the maximum power that can be input, the maximum power that can be input to the fixing unit is calculated after detecting the current consumption of each mechanism, and the heater current correction process and the heating time correction process are performed (step S406). Thereafter, when the set time of the corrected heating mode elapses (step S407 / YES) and the temperature of the fixing roller reaches a temperature corresponding to the amount of heat necessary for copying the remaining number of sheets, the image forming operation is resumed ( In step S408), the remaining number of copies is copied. When the set time of the heating mode does not elapse (step S407 / NO), the heating time is corrected again according to the pixel density and the heating is performed for the time after the correction.

  The correction of the heating time according to the paper type, pixel density, and image density will be described. Similar to the calculation of the required heat quantity for the remaining number of copies, the calculation of the required heat quantity for each paper type, each pixel density, and each image density is stored in advance in, for example, a memory unit in the main controller 501. The paper type, pixel density, and image density are detected by sensors in the main controller 501, for example. The necessary heat quantity is calculated based on the data detected by the sensor, and the heating time is corrected.

  The correction of the heating time according to the input voltage will be described. The calculation of the amount of heat required to copy the remaining number of sheets is as described above, but the time until the temperature rise corresponding to the calculation depends on the current. That is, the heating time varies depending on the current to the fixing unit. The sensor detects the input voltage to the fixing unit, calculates the time until the temperature rise corresponding to the required amount of heat based on the voltage value, and corrects the heating time. The detection of the input voltage can be performed without errors if the fixing heater is heated.

  Here, the maximum current during operation of each unit shown in FIG. 2 is set as follows. Current consumption in the power supply device during standby is 0.5 A, current consumption in the scanner and ADF during image reading is 1.0 A, current consumption during post-processing device operation such as a finisher is 1.0 A, and image forming operation Current consumption during sheet feeding and image formation, etc. is 2.5 A, current consumption in heater 1 is 8.0 A, current consumption in heater 2 is 3.0 A, and rated current of all devices is 15.0 A. . The current consumed during heating of the fixing heater is the current consumed by the power supply device and the like during standby and the current consumed by the heater. When the former is 0.5 A and the latter is 6 A, 6 A is detected by the sensor. The heating time is calculated and corrected based on the above.

  As described above, the heating time varies depending on the current. However, in other embodiments, the system connection state and the operating state in the heating mode are checked, and the maximum power is set within a range not exceeding the rating of the device. By putting it in the fixing heater, the heating time is shortened. This will be described below. The connection state and the operation state of the system are detected by the current detection element 516, and the current consumption of each device is grasped. Since the rated current of all the devices is determined, the power that can be supplied to the fixing unit can be calculated. Then, the maximum electric power is input to the heater within a range not exceeding the rated current of all devices.

  According to the above setting for the maximum current during operation of each mechanism, the current consumed during heating of the fixing heater is the current consumed by the power supply device and the like during standby and the current consumed by the heater. When the former is 0.5 A, the latter maximum current consumption in a range not exceeding the rated current of all devices is 11 A, and the heater can be heated with the maximum power based on this.

  The above-described embodiment is a preferred embodiment of the present invention, and the scope of the present invention is not limited to the above-described embodiment alone, and various modifications are made without departing from the gist of the present invention. Implementation is possible.

1 is a configuration of a fixing device according to an embodiment of the present invention. 1 is a block diagram illustrating a configuration of a digital multifunction peripheral according to an embodiment of the present invention. It is a control flow which concerns on embodiment of this invention. It is a control flow which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fixing roller 2 Main heater 3 Sub heater 4 Control driver 5 Control driver 6 Thermistor element for temperature detection 7 Thermistor element for temperature detection 8 CPU

Claims (5)

In an image forming apparatus including a heat fixing type fixing unit,
Heating means for heating the fixing unit;
Temperature detecting means for detecting the temperature of the fixing unit;
When the temperature of the fixing unit detected by the temperature detection unit is lower than the lower limit fixing temperature, the exposure and development operations are interrupted, and the fixing unit is heated for a predetermined time by the heating unit, and then the exposure and development operations are performed. And an image forming apparatus characterized by comprising:   The image forming apparatus according to claim 1, wherein the control unit changes a heating time of the fixing unit by the heating unit in accordance with a paper type of a transfer sheet being passed.   The image forming apparatus according to claim 1, wherein the control unit changes a heating time of the fixing unit by the heating unit according to a pixel density of an image being imaged.   4. The image forming apparatus according to claim 1, wherein the control unit changes a heating time of the fixing unit by the heating unit in accordance with an input voltage to the fixing unit. 5. .   5. The image according to claim 1, wherein the control unit heats the fixing unit by the heating unit with a maximum power that can be input in accordance with current consumption of each mechanism. 6. Forming equipment.

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