JP2007133174A - Image forming device, cooling control program and recording medium which can be read by computer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently carry out temperature control for a fixing device in an image forming device. <P>SOLUTION: The image forming device 100 is provided with a printing mode transferring toner to recording paper which is drawn from a paper supply tray by a paper supplying roller 1 on reception of a printing command by a receiving part 37 and then fixing by a fixing machine 6 in which the toner is heated by a heater lamp 34, and a standby mode waiting for the reception of the printing command. Here, the image forming device 100 is provided with a POUT2 sensor 22 installed on the recording paper transporting direction downstream side of the paper supplying roller 1 and detecting the recording paper reaching the fixing machine 6. Then, a cooling control part 32 stops the operation of a cooling fan 9 in the standby mode and driving of the cooling fan 9 is started according to detection by a POUT1 sensor 22 in the printing mode. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus that fixes a developer onto a recording sheet by a heated fixing unit.

  Examples of an image forming apparatus using an electrophotographic system include a copying machine, a printer, and a facsimile. In these image forming apparatuses, for example, an image is formed on a recording sheet based on image data input from a peripheral device.

  A general image forming process in such an image forming apparatus will be described as follows. FIG. 4 is a diagram illustrating a recording paper conveyance path. When the image forming apparatus receives the image data, first, the paper feeding roller 1 pulls the recording paper one by one from a paper feeding tray (not shown), and conveys the recording paper in the direction of the registration roller 2. A PIN sensor 21 is installed adjacent to the registration roller 2, and is detected by the PIN sensor 21 when the leading edge of the recording paper is conveyed to the registration roller 2.

  When the PIN sensor 21 detects the leading edge of the recording paper, the exposure optical system 5 scans and exposes the surface of the photoreceptor 4 charged by the charger 7 with laser light with reference to the timing, and the electrostatic latent image Form. A toner image is formed on the photoreceptor 4 on which the electrostatic latent image has been formed by the developing device 3 developing with toner (developer).

  Then, the toner image developed on the photoreceptor 4 is transferred onto the recording paper conveyed from the registration roller. The recording paper onto which the toner image has been transferred is conveyed to the fixing device 6 and is pressed by the heated heating roller 13 and the pressure roller 14 in the fixing device 6. As a result, the toner image is fixed on the recording paper. Thereafter, the recording paper on which the toner image is fixed is discharged from the image forming apparatus main body.

  In such an image forming apparatus, when the recording paper starts to pass through the heating roller and the pressure roller of the fixing device, the recording paper takes the heat of the heating roller and the pressure roller, and with the passage, the heating roller 13 and the pressure roller It is known that the temperature of 14 falls. For this reason, in order to maintain a sufficient fixing force until the passing of the recording paper is completed, it is necessary to take a sufficient warm-up time (time for heating the heating roller 13 and the pressure roller 14). In order to shorten the warm-up time, it is necessary to efficiently control the temperature of the heating roller 13 and the pressure roller 14.

  From this point of view, Patent Document 1 describes an image forming apparatus that increases the cooling capacity of a cooling fan after a predetermined time has elapsed in response to an instruction output instructing an image forming operation.

Patent Document 2 describes an image forming apparatus that stops rotation of a cooling fan when recording paper enters a fixing device and starts driving the fan again after the recording paper passes through the fixing device. Yes.
JP-A-6-274001 (published September 30, 1994) JP-A-9-114288 (published on May 2, 1997)

  However, the conventional image forming apparatus still has a problem that the temperature control of the heating roller 13 and the pressure roller 14 (that is, the fixing device 6) is not efficient.

  For example, in the image forming apparatus described in Patent Document 1, the timing for increasing the cooling capacity of the cooling fan is determined according to an instruction output for instructing an image forming operation. Therefore, when the instruction output is received, even if a recording paper pull-in error occurs before the recording paper is transported to the fixing device, the cooling capacity of the cooling fan automatically increases after a predetermined time. End up. As a result, the temperature of the fixing unit decreases at the time of reprinting after error recovery, and it is necessary to warm up again over a long time.

  On the other hand, in the image forming apparatus described in Patent Document 2, the cooling fan rotates at the same time as the power is turned on, and the driving of the cooling fan is stopped only when the recording paper passes through the fixing device. For this reason, the cooling fan is in a driven state before receiving a print instruction. Therefore, since the temperature of the fixing device is lowered when the printing instruction is received, it is not possible to quickly warm up. This problem becomes particularly noticeable when the image forming operation is performed in the morning.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus that can efficiently control the temperature of a fixing unit (fixing device).

  In order to solve the above-described problems, the present invention provides a receiving unit that receives an image forming command, a paper feed conveyance unit that draws and conveys recording paper from a paper feed tray, a fixing unit that fixes a developer on the recording paper, A heating unit that heats the fixing unit; a cooling unit that cools the fixing unit; and a cooling control unit that controls the operation of the cooling unit. An image forming mode in which the developer is transferred to the recording paper that has been pulled in by the conveyance unit, and the developer is fixed on the recording paper by the fixing unit heated by the heating unit, and waiting for reception of an image forming command. An image forming apparatus having two modes: a recording sheet detecting unit that detects that the recording sheet has been drawn by the sheet feeding and conveying unit, and the cooling control unit , Wait above It stops the operation of the cooling unit in over de, characterized in that to improve than before detecting the cooling power of the cooling unit in accordance with detection by the recording sheet detector in the image forming mode.

  According to the above configuration, in the standby mode, the cooling control unit stops the operation of the cooling unit. Therefore, it is possible to prevent the temperature in the apparatus from being excessively lowered during the standby mode, and to quickly warm up. In the print mode, the cooling control unit improves the cooling power of the cooling control unit in response to detection by the recording paper detection unit that detects that the recording paper has been drawn. Therefore, when the recording paper pull-in fails in the paper feeding / conveying unit or the like, the cooling control unit does not improve the cooling power of the cooling unit. Therefore, it is possible to prevent the temperature in the apparatus from being lowered before reprinting, and to quickly warm up. As described above, the image forming apparatus of the present invention can efficiently control the temperature of the fixing unit.

  Preferably, the recording paper detection unit is provided adjacent to the fixing unit and detects that the leading edge of the recording paper has been conveyed to the fixing unit.

  According to the above configuration, the cooling control unit improves the cooling power of the cooling unit in response to the leading edge of the recording paper being conveyed to the fixing unit. Therefore, even if an error occurs in the transport path from the paper feed transport unit to the fixing unit, it is possible to prevent the temperature in the apparatus from being lowered.

  In addition, the cooling control unit is detected by the recording paper detection unit so as to improve the cooling power of the cooling unit between the time when the recording paper reaches the fixing unit and the time when the passage is completed. It is preferable to improve the cooling power of the cooling section after a predetermined time has passed since the starting point.

  It is known that recording paper takes heat of the fixing unit when passing through the fixing unit. Here, according to the configuration of the present invention, the cooling power of the cooling unit is not improved until the recording paper reaches the fixing unit. Accordingly, it is possible to prevent the temperature of the fixing unit from being lowered below an appropriate temperature due to the recording paper reaching the fixing unit while the cooling power is improved. As a result, it is possible to prevent deterioration of fixing of the developer transferred to the recording paper.

  Further, normally, while the recording paper is passing through the fixing unit, the fixing unit is heated for the purpose of compensating for heat taken away by the recording paper. Therefore, when the recording paper passes, the temperature of the fixing unit rises. There is a tendency. Here, when the fixing unit is overheated, the next recording sheet conveyed to the fixing unit is curled by the heat of the fixing unit. However, according to the configuration of the present invention, since the cooling power is surely improved before the recording paper passes through the fixing portion, the temperature of the fixing portion rises too much after the recording paper has passed through the fixing portion. And can be kept at an appropriate temperature. This can also prevent the next recording paper from curling.

  The image forming apparatus further includes a temperature detection unit that is provided in the image forming apparatus and detects the temperature of the fixing unit, and the cooling control unit detects the predetermined time by the temperature detection unit. It is preferable to adjust the temperature according to the measured temperature.

  When the temperature of the fixing unit is high, it is desirable to improve the cooling power of the cooling unit early. Conversely, when the temperature of the fixing unit is low, it is desirable to improve the cooling power of the cooling unit later. According to the above configuration, since the cooling control unit adjusts the timing for improving the cooling power according to the temperature of the fixing unit, more efficient temperature control can be performed.

  The cooling control unit preferably adjusts the predetermined time according to a temperature detected by the temperature detection unit when an image forming command is received by the reception unit.

  According to the above configuration, the cooling control unit adjusts the “predetermined time” described above according to the temperature of the fixing unit at the time when the printing mode is started. Therefore, it is possible to accurately determine how long the fixing unit is in an overheated state in the print mode.

  The cooling control unit may adjust the predetermined time according to the time of the standby mode.

  For example, when the standby mode time is long, it is considered that the temperature of the fixing unit is sufficiently lowered, so it is desirable to improve the cooling power later. On the other hand, when the standby mode time is short, it is considered that the temperature of the fixing unit that has been raised during the previous image formation is not sufficiently lowered, so it is desirable to improve the cooling power early. According to the above configuration, since the cooling control unit adjusts the timing for improving the cooling power according to the time of the standby mode, more efficient temperature control can be performed.

  Further, the cooling control unit may adjust the predetermined time according to the type of the recording paper.

  The amount of heat taken from the fixing unit by the recording paper varies depending on the type of recording paper. Therefore, according to the above configuration, it is possible to perform more efficient temperature control by adjusting the timing at which the cooling control unit improves the cooling power according to the type of recording paper. Here, the type of recording paper includes, for example, the size of the recording paper, the weight of the recording paper, and the material of the recording paper. The cooling control unit may adjust the timing in consideration of all of these, or may adjust the timing in consideration of only one part, such as one or two.

  The image forming apparatus further includes a recording sheet counting unit that counts the amount of recording sheets on which images are continuously formed, and the cooling control unit is counted by the recording sheet counting unit in the image forming mode. When the amount of recording paper is a predetermined amount of recording paper, it is preferable that the cooling power of the cooling unit is improved as compared with that before detection in accordance with detection by the recording paper detection unit.

  According to the above configuration, when the image forming apparatus is configured to continuously form images on a plurality of recording sheets, the cooling power is reduced when the amount of the recording sheets on which the image is formed reaches a predetermined amount. Can be improved. Therefore, for example, even if only the image formation on one sheet of recording paper does not cause the inside of the apparatus to be overheated, the fixing unit is preferably overheated only after image formation on a plurality of sheets of recording paper. Temperature control can be performed.

  The image forming apparatus further includes a temperature detection unit that is provided in the image forming apparatus and detects a temperature, and the cooling control unit detects the amount of the predetermined recording sheet by the temperature detection unit. It is preferable to adjust according to the temperature.

  For example, when the temperature of the fixing unit is high, it is desirable to improve the cooling power of the cooling unit early. Conversely, when the temperature of the fixing unit is low, it is desirable to improve the cooling power of the cooling unit later. According to the above configuration, since the cooling control unit adjusts the timing for improving the cooling power in accordance with the temperature of the fixing unit, more efficient temperature control can be performed.

  The cooling control unit preferably adjusts the amount of the predetermined recording sheet according to the temperature detected by the temperature detecting unit when the image forming command is received by the receiving unit.

  According to the above configuration, the cooling control unit adjusts the “predetermined amount of recording paper” described above according to the temperature of the fixing unit at the time when the printing mode is started. Therefore, it is possible to accurately determine how much amount of recording paper the fixing unit prints in the print mode when the printer is overheated.

  The cooling control unit may adjust the amount of the predetermined recording sheet according to the time of the standby mode.

  For example, when the standby mode time is long, it is considered that the temperature of the fixing unit is sufficiently lowered, so it is desirable to improve the cooling power later. On the other hand, when the standby mode time is short, it is considered that the temperature of the fixing unit that has been raised during the previous image formation is not sufficiently lowered, so it is desirable to improve the cooling power early. According to the above configuration, the cooling control unit adjusts the timing for improving the cooling power according to the time of the standby mode, so that more efficient temperature control can be performed.

  Further, the cooling control unit may adjust the amount of the predetermined recording sheet according to the type of the recording sheet.

  The amount of heat taken from the fixing unit by the recording paper varies depending on the type of recording paper. According to the above configuration, more efficient temperature control can be performed by adjusting the timing at which the cooling control unit improves the cooling power according to the type of recording paper. Here, the type of recording paper includes, for example, the size of the recording paper, the weight of the recording paper, and the material of the recording paper. The cooling control unit may adjust the timing in consideration of all of these, or may adjust the timing in consideration of only one part, such as one or two.

  The image forming apparatus is provided in the image forming apparatus, and includes a temperature detecting unit that detects a temperature, and an abnormality detecting unit that detects an abnormality that has occurred after the paper feeding / conveying unit has pulled the paper from the paper feeding tray. And when the cooling control unit detects an abnormality in the image forming mode by the abnormality detection unit and a temperature higher than a predetermined temperature is detected by the temperature detection unit. It is preferable to improve the cooling power of the cooling unit as compared to before detection.

  According to said structure, when abnormality is detected, it can prevent that the inside of an apparatus will be in an overheated state. Here, since the cooling control unit improves the cooling power of the cooling unit only when a temperature higher than the predetermined temperature is detected, it is possible to prevent the inside of the apparatus from being cooled more than necessary. .

  The image forming apparatus further includes a temperature detection unit that is provided in the image forming apparatus and detects a temperature, and the cooling control unit is based on the temperature detected by the temperature detection unit in the standby mode. It is preferable to stop the operation of the cooling unit.

  According to the above configuration, when the inside of the apparatus is overheated after the end of the image forming mode or the like, the cooling power of the cooling unit is maintained as it is, and when the temperature becomes below or below a predetermined temperature, the cooling unit Stop the operation. As described above, the apparatus can be prevented from being overheated in the standby mode.

  The cooling control unit may stop the operation of the cooling unit after a predetermined time has elapsed since the end of the image forming mode when the image forming mode is shifted to the standby mode.

  According to the above configuration, the operation of the cooling unit is stopped after a predetermined time from the end of the image forming mode. Therefore, it is possible to prevent the apparatus from being overheated in the standby mode.

  Incidentally, the cooling control unit of the image forming apparatus may be realized by hardware, or may be realized by causing a computer to execute a program. Specifically, the cooling control program according to the present invention is a program that causes a computer to operate as the cooling control unit, and the program is recorded in the recording medium according to the present invention.

  When these programs are executed by a computer, the computer operates as the cooling control unit. Therefore, the image forming apparatus can efficiently control the temperature of the fixing unit.

  As described above, the image forming apparatus according to the present invention includes the recording paper detection unit that detects that the recording paper is being pulled in by the paper feed conveyance unit, and the cooling control unit is in the standby mode. The operation of the cooling unit is stopped, and the cooling power of the cooling unit is improved as compared with that before the detection in accordance with the detection by the recording paper detection unit in the image forming mode. Therefore, as described above, there is an effect that the temperature control of the fixing unit can be performed efficiently.

  An embodiment of the present invention will be described below with reference to FIGS. 2 and 3 are longitudinal sectional views showing a schematic configuration of the image forming apparatus 100 of the present embodiment. FIG. 4 is a diagram showing a recording paper conveyance path. As shown in FIG. 2, the image forming apparatus 100 includes a paper feeding roller (paper feeding / conveying unit) 1, a registration roller 2, a developing device 3, a photosensitive member 4, an exposure optical system 5, a fixing device (fixing unit) 6, a charging unit. A container 7 and a transfer roller 8 are provided.

  The paper feed roller 1 is for drawing recording sheets one by one from a paper feed tray (not shown). In this specification, “pulling in” means that the paper feed roller (paper feed transport unit) 1 is rotated downstream of the paper feed tray in the recording paper transport direction (that is, the photoreceptor 4 and the fixing device) by the rotation of the roller. 6 side).

  The registration roller 2 is used for conveying the recording paper drawn by the paper feeding roller 1 to a photoconductor 4 described later and determining timing for forming an image on the recording paper. In order to determine this timing, as shown in FIG. 4, a PIN sensor 21 is provided adjacent to the registration roller 2 on the downstream side in the recording paper conveyance direction. The PIN sensor 21 is a sensor for detecting the leading edge of the recording paper, and can detect the timing at which the leading edge of the recording paper passes the registration roller 2.

  The charger 7 is for charging the surface of the photoreceptor 4 with electric charges. The exposure optical system 5 performs scanning exposure on the surface of the photoreceptor 4 charged by the charger 7 to form an electrostatic latent image. The developing device 3 is for developing the surface of the photoreceptor 4 on which the electrostatic latent image is formed with toner (developer).

  The transfer roller 8 is for transferring the toner image onto the recording paper by sandwiching the recording paper with the photoreceptor 4 on which the toner image is formed. The fixing device 6 includes a heating roller 13 and a pressure roller 14, and these rollers sandwich and press the recording paper in a state of being heated by a built-in heater lamp (heating unit). This is for fixing the transferred toner image.

  Further, as shown in FIG. 4, a POUT1 sensor 22 is provided on the downstream side of the fixing device 6 in the recording paper conveyance direction. The POUT1 sensor 22 is for detecting the passage of the leading and trailing edges of the recording paper, and can thereby detect the timing when the recording paper reaches the fixing device 6 and the completion timing of the passage. Specifically, the POUT1 sensor 22 changes from off to on when the leading edge of the recording paper reaches the POUT1 sensor 22, and changes from on to off when the trailing edge of the recording paper passes through the POUT1 sensor 22. . Further, the image forming apparatus 100 includes a POUT2 sensor 23 in a discharge unit that discharges recording paper to the outside of the apparatus. The POUT2 sensor 23 is used to detect the passage of the leading and trailing ends of the recording paper in the same manner as the POUT1 sensor 22, and thereby detects that the recording paper has been discharged out of the image forming apparatus 100. can do.

  The image forming apparatus 100 further includes a cooling fan 9, a main motor 10, and a sub motor 11, as shown in FIG.

  The cooling fan 9 is mainly for lowering the temperature in the image forming apparatus, which has been raised by heating the fixing device 6, by ventilating the inside of the apparatus. The main motor 10 is for generating a driving force for rotating the registration roller 2, the photoconductor 4, the heating roller and the pressure roller included in the fixing device 6. The sub motor 11 is for generating a driving force to rotate the paper feed roller 1.

  A printing operation in such an image forming apparatus will be described as follows. When a receiving unit (not shown) of the image forming apparatus receives the image data, the image forming apparatus 100 changes from the standby mode to the printing mode (image forming mode). In the printing mode, first, the sheet feeding roller 1 pulls recording sheets one by one from a sheet feeding tray (not shown), and conveys the recording sheet in the direction of the registration roller 2.

  When the PIN sensor 21 provided adjacent to the registration roller 2 detects the leading edge of the recording paper, the photosensitive member 4 is scanned based on the detected timing so that an image is formed at an accurate position on the recording paper. Exposure is performed. More specifically, when the main motor 10 for transporting the recording paper is driven by a predetermined number of steps Sn from the reference timing (or the time Tsn required for the main motor 10 to be driven by the predetermined number of steps Sn is reduced). After the elapse of time, the exposure optical system 5 starts scanning exposure with laser light on the surface of the photoconductor 4 charged in advance by the charger 7. By scanning exposure, an electrostatic latent image is formed on the surface of the photoreceptor 4. The developing device 3 develops the photoreceptor 4 on which the electrostatic latent image is formed with toner, and a toner image is formed.

  The recording sheet conveyed by the registration roller 2 is sandwiched between the photosensitive member 4 and the transfer roller 8, whereby the developed toner image is transferred onto the photosensitive member 4. The recording paper onto which the toner image has been transferred is conveyed to the fixing device 6 and is pressed by the heated heating roller 13 and the pressure roller 14 in the fixing device 6. As a result, the toner image is fixed on the recording paper.

  The recording paper on which the toner image is fixed is then discharged from the main body of the image forming apparatus 100. A POUT2 sensor 23 is provided in the vicinity of the discharge portion of the image forming apparatus 100, so that it can be detected that the recording paper has been discharged. Here, when the next recording sheet is not conveyed in the image forming apparatus, the image forming apparatus 100 ends the printing mode and enters the standby mode. In the standby mode, the image forming apparatus 100 waits for reception of a print command.

  In the image forming apparatus as described above, the temperature control of the fixing device 6 (the heating roller 13 and the pressure roller 14) will be described as follows. The temperature control of the fixing device 6 is performed by controlling the heating power of the heater lamp 34 built in the heating roller 13 and the pressure roller 14 and the cooling power of the cooling fan 9 that cools the inside of the apparatus.

  FIG. 1 is a functional block diagram showing the relationship of each block related to temperature control. As shown in FIG. 1, the temperature control for the fixing device 6 of the image forming apparatus 100 includes a temperature control unit 30, a POUT1 sensor (recording paper detection unit) 22, a sheet count unit 33, a heater lamp 34, a cooling fan 9, and temperature detection. This is realized by the unit 35, the timer 36, the receiving unit 37, and the like.

  As described above, the heater lamp 34 is for heating the fixing device 6 (the heating roller 13 and the pressure roller 14), and the cooling fan 9 is for cooling the fixing device 6 by ventilating the inside of the apparatus. Is. The temperature control unit 30 includes a temperature control unit 31 that controls on / off of the heater lamp 34 and a cooling control unit 32 that controls on / off of the cooling fan 9. The temperature can be controlled.

  The POUT1 sensor 22 can detect the recording paper passing through the fixing device 6 as described above. More specifically, the detection signal of the POUT1 sensor 22 is turned on when the leading edge of the recording paper reaches, and then the detection signal is turned off when the trailing edge of the recording paper passes. Thereby, when the detection signal of the POUT1 sensor 22 changes from OFF to ON, it can be seen that the recording paper has reached the fixing device 6, and when the detection signal changes from ON to OFF, the recording paper is fed to the fixing device 6. You can see that the passage is complete.

  The number counting unit 33 counts the number of recording sheets that have passed through the POUT1 sensor continuously. Here, “continuously passes” means, for example, that the time from when a certain recording sheet passes until the next recording sheet passes is not more than a predetermined time.

  The temperature detection unit 35 is provided in the image forming apparatus 100 and detects the temperature of the fixing device 6 (heating roller 13). The timer 36 is for counting time. The receiving unit 37 is for receiving a print command from a personal computer or the like.

  Next, control of the heater lamp 34 by the temperature control unit 31 will be described with reference to FIG. As shown in FIG. 5, the temperature control unit 31 has two modes of off and on. The off mode refers to a mode in which the temperature control unit 31 is stopped and the heater lamp 34 is not on / off controlled. Further, the on mode means that the temperature adjustment control unit 31 sets the heater lamp 34 to the fixing device 6 (the heating roller 13 and the heating roller) so that the fixing device 6 has an appropriate temperature (t1) for fixing the toner on the recording paper. It refers to a mode in which the pressure roller 14) is appropriately heated.

  In the standby mode, the temperature control unit 31 is in the off mode. Here, when the receiving unit 37 receives the print command, the image forming apparatus 100 enters the print mode. Along with this, the temperature control unit 31 enters the on mode. In the on mode, the temperature control unit 31 controls on / off of the heater lamp 34 so that the heating roller 13 has an appropriate temperature t1. As a result, when the heater lamp 34 starts heating the heating roller 13 and then the recording paper passes through the fixing device 6, the heat deprived from the fixing device 6 by the recording paper is appropriately compensated, and the temperature of the heating roller 13 is increased. Keep at t1. Note that the temperature control at this time is performed based on the temperature detected by the temperature detector 35.

  Then, when the recording paper passes through the POUT1 sensor 22 (that is, when the POUT1 sensor 22 changes from on to off), the image forming apparatus 100 enters the standby mode. Along with this, the temperature control unit 31 is also in the off mode. When continuously printing on a plurality of recording sheets, the image forming apparatus 100 enters a standby mode when the last recording sheet passes through the POUT1 sensor 22, and the temperature control unit 31 is turned off. Become a mode.

  Next, control of the cooling fan 9 by the cooling control unit 32 will be described with reference to FIGS. 5 and 6. In the present embodiment, the on / off control of the cooling fan 9 is performed in response to the detection signal of the POUT1 sensor 22. In the following description, it is assumed that the cooling control unit 32 performs each process unless otherwise specified.

  In the standby mode when the power is turned on, the cooling control unit 32 stops driving the cooling fan 9. Here, when the receiving unit 37 receives the print command (S11), the image forming apparatus 100 enters the print mode and proceeds to step S12. On the other hand, when the receiving unit 37 has not received the print command, the image forming apparatus 100 stands by in the standby mode.

  In step S12, it is determined whether or not the temperature t detected by the temperature detector 35 is higher than a predetermined temperature t2. If the detected temperature t is higher than the predetermined temperature t2, the cooling control unit 32 proceeds to step S19 and drives the cooling fan. If the temperature is equal to or lower than the predetermined temperature t2, the process proceeds to step S13.

  Subsequently, in step S13, it is determined whether or not the number p counted by the number counting unit 33 has reached a predetermined number p1. If the number p is less than the predetermined number p1, the process proceeds to step S20, and it is determined whether or not printing is completed. In the present embodiment, the end of printing is determined by the POUT1 sensor 22 detecting that the last recording sheet among the continuously printed recording sheets passes. When the printing is finished in step S20, the process proceeds to step S23, and the cooling control is finished while the cooling fan is stopped. If printing has not ended, the process returns to step S13 again to determine whether or not the number p counted by the number counting unit 33 is a predetermined number p1.

  On the other hand, if it is determined in step S13 that the predetermined number is p1, the process proceeds to step S14. In step S14, the timer 36 is reset, and the process proceeds to step S15. In step S15, it is determined whether the detection signal of the POUT1 sensor 22 has been turned on from off.

  Here, when the detection signal of the POUT1 sensor 22 changes from OFF to ON in step S15 (that is, when the p1th recording sheet reaches the fixing unit 6), the process proceeds to step S16 and the timer 36 counts up. To start. On the other hand, if it has not changed from off to on, the process returns to step S15 to determine again whether or not the detection signal of the POUT1 sensor 22 has changed from off to on.

  In step S16, after the timer 36 starts counting up, the process proceeds to step S17, and it is determined whether or not the time T counted by the timer 36 exceeds a predetermined time T1. Here, if the counted time T does not exceed the predetermined time T1, the process proceeds to step S21, and it is determined whether or not printing is completed. If printing has not ended, the process returns to step S17, and it is determined again whether or not the counted time T has exceeded the predetermined time T1. On the other hand, when printing is finished, the timer 36 stops counting up (S22), and the cooling fan is stopped (S23), and the cooling control is finished.

  If the predetermined time is exceeded in step S17, the process proceeds to step S18 to stop the count-up of the timer 36, and then the cooling fan is started to be driven in step S19. Thereby, the driving of the cooling fan is started and the cooling control is ended.

  As described above, in the image forming apparatus 100 of the present embodiment, the cooling control unit 32 after a predetermined time in response to the detection of the passage of the recording paper by the POUT1 sensor 22 provided adjacent to the fixing device 6. Starts driving the cooling fan. Therefore, when the recording paper does not reach the fixing device 6 due to clogging or the like in the conveyance path from the paper feed roller 1 to the fixing device 6, the cooling control unit 32 starts driving the cooling fan 9. There is nothing. As a result, when reprinting is performed after an error has occurred, the temperature of the fixing device 6 does not decrease, and the warm-up time can be shortened.

  Note that the predetermined temperature t2 in the above step S12 may be determined with reference to a temperature that can damage each part in the apparatus. According to step S <b> 12, it is possible to prevent the temperature inside the apparatus from abnormally rising due to the heated fixing device 6 and damaging each part due to heat. At this time, the cooling control unit 32 starts driving the cooling fan 9 only when the temperature is equal to or higher than the predetermined temperature. Therefore, the cooling control unit 32 does not start driving the cooling fan 9 even though the temperature of the fixing device 6 is low. . Therefore, before the recording paper reaches the fixing device 6, the temperature of the fixing device 6 is not decreased more than necessary, and the temperature increase of the fixing device 6 is not hindered.

  Further, the predetermined number p1 in step S13 is preferably determined as appropriate according to the characteristics of the fixing device 6, the content of the heating control, and the like. It is possible to determine whether or not the inside of the apparatus is overheated when printing is performed, and to determine based on the number of sheets. In this way, the cooling control unit 32 starts driving the cooling fan 9 after a predetermined number of recording sheets have been printed. Therefore, the cooling fan 9 is driven even though the temperature in the apparatus has not risen sufficiently. By doing so, it is possible to prevent the temperature of the fixing device 6 from being lowered or the temperature of the fixing device 6 from being hindered when fixing the subsequent recording paper.

  In the present embodiment, the number counting unit 33 is configured to count the number of recording sheets detected by the POUT1 sensor 22, but the present invention is not limited to this. Instead of the POUT1 sensor 22, the POUT2 sensor is used. The number of recording sheets detected by sensors provided at other positions such as 23 and the PIN sensor 21 may be counted. Further, when the image forming apparatus 100 is compatible with double-sided printing, the number of printed pages may be counted instead of counting the number of recording sheets. Furthermore, since the amount to be printed varies depending on the size of the recording paper even with the same number of pages and the number of pages, the area of the printed recording paper may be counted in consideration of this.

  In addition, it is preferable that the cooling control unit 32 appropriately adjust the predetermined number p1 according to various conditions during printing. As an example, the cooling control unit 32 may adjust the predetermined number p <b> 1 according to the temperature in the apparatus detected by the temperature detection unit 35. In this configuration, when the temperature in the apparatus is high, the value of p1 is decreased, and when the temperature in the apparatus is low, the value of p1 is increased, whereby the cooling control considering the temperature in the apparatus can be performed. . The timing at which the temperature detection unit 35 detects the temperature is not particularly limited. For example, the timing at which the reception unit 37 receives a print command may be used. According to this, since the predetermined number of sheets can be determined based on the temperature at the time when the print command is received and the print mode is switched, how much the temperature in the apparatus rises in the print mode thereafter. More accurate judgment can be made.

  As another example, the cooling control unit 32 may adjust the predetermined number p1 according to the time of the standby mode. The time in the standby mode corresponds to the time from the end of a certain print mode to the start of the next print mode. In this embodiment, this is from the time when the POUT2 sensor 23 detects that the trailing edge of the last recording paper passes in the previous print mode to the time when the receiving unit 37 receives the print command in the next print mode. Is equivalent to When the standby mode is long, it is expected that the temperature inside the device has been sufficiently lowered. On the other hand, when the standby mode is short, the temperature inside the device is not sufficiently lowered and is expected to be high. The Therefore, the cooling control can be appropriately performed by increasing the value of p1 when the standby mode is long, and decreasing the value of p1 when the standby mode is short.

  As yet another example, the cooling control unit 32 may adjust the predetermined number p1 according to the type of recording paper. For example, when the size of the recording paper is large, the amount of heat taken by one recording paper from the fixing device 6 also increases. Accordingly, when the recording paper size is large, the value of p1 is increased to delay the driving of the cooling fan 9, and when the recording paper size is small, the driving of the cooling fan is accelerated by decreasing the value of p1. Is preferred. Thereby, it is possible to appropriately control the cooling in consideration of the size of the recording paper. Further, the predetermined number p1 may be adjusted according to not only the size of the recording paper but also the weight and material of the recording paper. In these cases, the recording paper type information may be notified to the image forming apparatus 100 by the user or a computer used by the user. Also, the size of the recording paper is determined by measuring the length of the recording paper by measuring the time from when each of the sensors 21 to 23 is turned ON from OFF to the timing when it is turned ON. The size may be estimated.

  Note that the predetermined time T1 in the above step S17 can be set to be equal to or less than the time required for the trailing edge of the recording paper to pass through the fixing device after the leading edge of the recording paper reaches the fixing device 6.

  Usually, when the recording paper passes through the fixing device, the heat of the fixing device is taken away by the recording paper, so that the fixing device needs to be heated. As a result, after the recording paper passes through the fixing device 6, the temperature of the fixing device 6 tends to increase. Here, according to the configuration described above, the cooling fan 9 starts to be driven after the recording paper reaches the fixing device 6 until the recording paper is completely passed. Therefore, after completion of the passage of the recording paper, the fixing device 6 can be surely cooled, and the next recording paper can be prevented from curling.

  Further, in this case, since the passing time varies depending on the size of the recording paper (A3, A4, A5, etc.), it is preferable that the cooling control unit 32 adjust the predetermined time T1 according to the size of the recording paper. .

  In the present embodiment, the timer 36 starts counting up at a time when the detection signal of the POUT1 sensor 22 changes from OFF to ON (that is, when the leading edge of the recording paper reaches the fixing unit 6). After T1 has elapsed, the cooling control unit 32 starts driving the cooling fan 9, but instead, when the POUT1 sensor 22 is attached upstream of the fixing unit 6, the detection signal of the POUT1 sensor 22 is turned on. The driving of the cooling fan 9 may be started immediately without counting up the timer at the time when it is turned off (that is, when the trailing edge of the recording paper passes through the fixing unit 6). That is, the cooling control unit 32 may start driving the cooling fan 9 in response to the POUT1 sensor 22 detecting that the trailing edge of the recording paper has passed the fixing unit 6. In this case, the cooling fan 9 is started at the same time as the recording paper completes the passage of the fixing device 6, so that the temperature of the fixing device 6 is prevented from decreasing before the toner is fixed, and the recording paper is used. It is possible to prevent overheating that occurs after passing through.

  In the present embodiment, the cooling fan is driven when the number of continuously printed recording sheets reaches the predetermined number p1, but the present invention is not limited to this, and the first sheet is printed. The timer 36 may start counting up when the leading edge of the recording paper to be detected is detected by the POUT1 sensor 22. In this case, in the cooling control process described above, if the temperature detected by the temperature detector 35 does not exceed t2 in step S12, the configuration may be changed to proceed to step S14.

  In this case, the predetermined time T1 is preferably determined as appropriate in accordance with the characteristics of the fixing device, the contents of the heating control, and the like. For example, when the recording paper is continuously printed by an experiment or the like in advance, the apparatus It is possible to determine whether or not the inside is overheated and to determine based on the time.

  Also in this case, similarly to p1 described above, it is preferable that the cooling control unit 32 appropriately adjust T1 according to various conditions during printing. That is, it is preferable that the cooling control unit 32 adjust the predetermined time T <b> 1 according to the temperature detected by the temperature detection unit 35. The timing at which the temperature detection unit 35 detects the temperature is not particularly limited, but may be, for example, the timing at which the reception unit 37 receives a print command. Further, the cooling control unit 32 may adjust the predetermined time T1 according to the time in the standby mode, or may adjust according to the type of recording paper. With these configurations, it is possible to obtain substantially the same effects as in the case of adjusting p1 described above.

  By the way, when the driving of the cooling fan 9 is started in step S19, the timing at which the cooling control unit 32 stops the driving of the cooling fan 9 includes, for example, one of the following two timings. First, the first timing may be a predetermined time after the end of the printing mode. In this case, the predetermined time can be determined based on the time required for the cooling fan 9 to sufficiently reduce the temperature in the apparatus after the printing mode is completed in advance through experiments. Instead of using the end of the print mode as a base point, the base point may be a time point when the last recording sheet is discharged from the image forming apparatus 100 (that is, a time point when the POUT2 sensor 23 is turned off from on).

  As the second timing, after the cooling fan 9 is driven, the temperature detection unit 35 detects the temperature at any time, and the timing when the detected temperature becomes equal to or lower than a predetermined temperature (less than). . In this case, it is desirable that the predetermined temperature is low enough not to damage each part in the apparatus and high enough to quickly warm up the fixing device 6.

  As described above, the image forming apparatus 100 according to the present embodiment stops the cooling fan 9 in the standby mode immediately after the power is turned on. Even when the cooling fan is driven in the standby mode after printing, the driving of the cooling fan is stopped based on a predetermined time or a predetermined temperature. Thereby, the fixing device 6 is not excessively cooled in the standby mode, and warm-up can be quickly performed at the time of the next printing.

  Note that the image forming apparatus 100 of the present embodiment further includes an abnormality detection unit (not shown) as a more preferable form. This abnormality detection unit is for detecting an error when the recording paper is drawn by the paper feed roller 1 and an error thereafter. When an error such as a paper jam is notified from the abnormality detection unit in the print mode, the cooling control unit 32 refers to the temperature detected by the temperature detection unit 35, and cools if this temperature exceeds a predetermined temperature. The drive of the fan 9 is started.

  According to such a configuration, when an error occurs before the recording paper arrives at the fixing device 6, it is possible to prevent a fire or damage of each part from occurring due to an excessive increase in the temperature in the apparatus. . In this case, the cooling control unit 32 does not simply stop the driving of the cooling fan 9 but stops the driving of the cooling fan 9 based on the temperature in the apparatus. There is no risk of hindrance.

  In this embodiment, a POUT1 sensor 22 provided adjacent to the fixing device 6 is used as a recording paper detection unit for detecting that the recording paper has been drawn by the paper supply roller 1. Using. Here, “the drawing is completed” means that in this embodiment, the trailing edge of the recording paper conveyed by the paper supply roller 1 is separated from the paper supply roller 1 to the downstream side in the recording paper conveyance direction. Accordingly, it is intended that the recording paper in a state where the drawing by the paper feed roller 1 has been completed does not cause an error such as a paper jam when in contact with the paper feed roller 1.

  By the way, the recording paper detection unit in the present invention is not limited to the configuration of the POUT1 sensor 22 provided adjacent to the fixing device 6, and may be a sensor provided at another position. For example, the PIN sensor 21 provided adjacent to the registration roller 2, the POUT2 sensor 23 provided near the discharge unit, or another sensor may be provided separately. In other words, the recording paper detection unit that detects that the recording paper has been pulled in by the paper feeding conveyance unit is downstream from the paper feeding conveyance unit by a distance longer than the length of the recording paper in the conveyance direction. A sensor provided on the side can be used. According to this configuration, the recording paper detection unit can detect the recording paper after being normally drawn by the paper feed roller 1, and the cooling fan 9 is driven at least when the recording paper pull-in by the paper feed roller 1 fails. Can be avoided.

  Finally, the temperature adjustment control unit 31 and the cooling control unit 32 of the image forming apparatus 100 may be configured by hardware logic, or may be realized by software using a CPU as follows.

  That is, the image forming apparatus 100 develops a CPU (central processing unit) that executes instructions of a temperature control program and a cooling control program that realize each function, a ROM (read only memory) that stores the program, and the program. A RAM (random access memory), a storage device (recording medium) such as a memory for storing the program and various data, and the like are provided. An object of the present invention is a recording medium in which program codes (execution format program, intermediate code program, source program) of each control program of the image forming apparatus 100, which is software that realizes the functions described above, are recorded so as to be readable by a computer. This can also be achieved by supplying the above to the image forming apparatus 100 and reading and executing the program code recorded on the recording medium by the computer (or CPU or MPU).

  Examples of the recording medium include a tape system such as a magnetic tape and a cassette tape, a magnetic disk such as a floppy (registered trademark) disk / hard disk, and an optical disk such as a CD-ROM / MO / MD / DVD / CD-R. Card system such as IC card, IC card (including memory card) / optical card, or semiconductor memory system such as mask ROM / EPROM / EEPROM / flash ROM.

  The image forming apparatus 100 may be configured to be connectable to a communication network, and the program code may be supplied via the communication network. The communication network is not particularly limited. For example, the Internet, intranet, extranet, LAN, ISDN, VAN, CATV communication network, virtual private network, telephone line network, mobile communication network, satellite communication. A net or the like is available. Also, the transmission medium constituting the communication network is not particularly limited. For example, even in the case of wired such as IEEE 1394, USB, power line carrier, cable TV line, telephone line, ADSL line, etc., infrared rays such as IrDA and remote control, Bluetooth ( (Registered trademark), 802.11 wireless, HDR, mobile phone network, satellite line, terrestrial digital network, and the like can also be used. The present invention can also be realized in the form of a computer data signal embedded in a carrier wave in which the program code is embodied by electronic transmission.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims. That is, embodiments obtained by combining technical means appropriately changed within the scope of the claims are also included in the technical scope of the present invention.

  According to the present invention, it is possible to realize an image forming apparatus capable of efficiently performing temperature control of the fixing unit. Therefore, it can be suitably applied to a general laser printer or the like.

1 is a functional block diagram illustrating a configuration of a main part related to temperature control of an image forming apparatus according to an embodiment of the present invention. 1 is a cross-sectional view illustrating a schematic structure of an image forming apparatus according to an embodiment of the present invention. 1 is a cross-sectional view illustrating a schematic structure of an image forming apparatus according to an embodiment of the present invention. It is a figure which shows a recording paper conveyance path | route. FIG. 2 is a diagram illustrating an embodiment of the present invention and a state of temperature control of the image forming apparatus. FIG. 3 is a flowchart illustrating a flow in controlling a cooling fan according to an embodiment of the present invention.

Explanation of symbols

1 Paper feed roller (paper feed transport)
6 Fixing device (fixing part)
9 Cooling fan (cooling part)
21 PIN sensor (recording paper detector)
22 POUT1 sensor (recording paper detector)
23 POUT2 sensor (recording paper detector)
32 Cooling control unit (cooling control unit)
33 Number of sheets counting section (recording paper counting section)
34 Heater lamp (heating unit)
35 Temperature detector (temperature detector)
37 Receiver (Receiver)
100 Image forming apparatus

Claims (17)

A receiving unit that receives an image forming command, a paper feeding / conveying unit that pulls and conveys recording paper from a paper feeding tray, a fixing unit that fixes a developer on the recording paper, a heating unit that heats the fixing unit, and the fixing unit A recording unit that cools the recording unit and a cooling control unit that controls the operation of the cooling unit. An image forming apparatus having two modes: an image forming mode in which a developer is transferred and the developer is fixed on a recording sheet by a fixing unit heated by the heating unit; and a standby mode in which an image forming command is received. There,
A recording paper detecting unit for detecting that the recording paper is being pulled in by the paper feeding and conveying unit;
The cooling control unit stops the operation of the cooling unit in the standby mode, and further improves the cooling power of the cooling unit in accordance with the detection by the recording paper detection unit in the image forming mode than before detection. An image forming apparatus as a feature. The image forming apparatus according to claim 1,
The image forming apparatus, wherein the recording sheet detection unit is provided adjacent to the fixing unit and detects that the leading edge of the recording sheet has been conveyed to the fixing unit. The image forming apparatus according to claim 1, wherein
When the detection by the recording paper detection unit is performed so as to improve the cooling power of the cooling unit between the time when the recording paper reaches the fixing unit and the time when the cooling is completed. An image forming apparatus, wherein the cooling power of the cooling unit is improved after a predetermined time has elapsed. The image forming apparatus according to claim 3, wherein
A temperature detection unit provided in the image forming apparatus for detecting the temperature of the fixing unit;
The image forming apparatus, wherein the cooling control unit adjusts the predetermined time according to a temperature detected by the temperature detection unit. The image forming apparatus according to claim 4,
The cooling control unit adjusts the predetermined time according to a temperature detected by the temperature detection unit when an image formation command is received by the reception unit. . The image forming apparatus according to any one of claims 3 to 5,
The image forming apparatus, wherein the cooling control unit adjusts the predetermined time according to the time of the standby mode. The image forming apparatus according to any one of claims 3 to 6,
The image forming apparatus, wherein the cooling control unit adjusts the predetermined time according to a type of the recording paper. The image forming apparatus according to any one of claims 1 to 7,
A recording paper counting unit that counts the amount of recording paper on which images are continuously formed;
In the image forming mode, when the amount of recording paper counted by the recording paper counting unit is a predetermined amount of recording paper, the cooling control unit responds to the detection by the recording paper detection unit. An image forming apparatus characterized in that the cooling power of the apparatus is improved as compared with that before detection. The image forming apparatus according to claim 8, wherein
A temperature detection unit provided in the image forming apparatus for detecting temperature;
The image forming apparatus, wherein the cooling control unit adjusts the amount of the predetermined recording sheet in accordance with the temperature detected by the temperature detection unit. The image forming apparatus according to claim 9, wherein
The cooling control unit adjusts the amount of the predetermined recording paper in accordance with a temperature detected by the temperature detection unit when an image forming command is received by the reception unit. Image forming apparatus. The image forming apparatus according to any one of claims 8 to 10,
The image forming apparatus, wherein the cooling control unit adjusts the amount of the predetermined recording sheet in accordance with the time of the standby mode. The image forming apparatus according to any one of claims 8 to 11,
The image forming apparatus according to claim 1, wherein the cooling control unit adjusts the amount of the predetermined recording sheet in accordance with the type of the recording sheet. The image forming apparatus according to any one of claims 1 to 12,
A temperature detector provided in the image forming apparatus for detecting temperature;
An abnormality detection unit that detects an abnormality that has occurred after the paper feeding conveyance unit pulls in from the paper feeding tray;
When the cooling control unit detects an abnormality in the image forming mode by the abnormality detection unit and a temperature higher than a predetermined temperature is detected by the temperature detection unit, the cooling unit An image forming apparatus characterized in that the cooling power is improved as compared with that before detection. The image forming apparatus according to any one of claims 1 to 13,
A temperature detection unit provided in the image forming apparatus for detecting temperature;
The image forming apparatus, wherein the cooling control unit stops the operation of the cooling unit based on the temperature detected by the temperature detection unit in the standby mode. The image forming apparatus according to any one of claims 1 to 13,
The cooling control unit stops the operation of the cooling unit after a predetermined time has elapsed from the end of the image forming mode when the image forming mode is shifted to the standby mode. .   A cooling control program for operating the image forming apparatus according to claim 1, wherein the cooling control program causes a computer to function as the cooling control unit.   A computer-readable recording medium on which the program according to claim 16 is recorded.

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