JP4642433B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus, and more particularly to an apparatus that controls the rotation speed of a cooling fan that radiates heat generated inside the image forming apparatus to the outside of the image forming apparatus.

  In an image forming apparatus such as a copying machine, a printer, and a facsimile, a fixing device and an exposure device are heated during the operation. That is, in the fixing device that fixes toner on the recording paper, when the recording paper passes through the fixing roller, the toner attached to the recording paper is melted by the fixing roller heated by the heater. Further, in an exposure apparatus that exposes an original, the exposure lamp generates heat when the exposure lamp is turned on when an image on the original is read. At this time, the heat of the fixing roller and the heat of the exposure lamp are radiated to the surroundings, and each device inside the image forming apparatus is heated.

  On the other hand, a cooling fan is provided in the vicinity of the fixing device and the exposure device in the image forming apparatus, and the cooling fan is driven to dissipate heat inside the image forming apparatus to the outside of the image forming apparatus. Heat or exposure lamp heat accumulates inside the image forming apparatus, the temperature inside the image forming apparatus rises excessively, and the toner contained in the developing apparatus is solidified, or the electrons inside the image forming apparatus The occurrence of fatal damage such as breakage of parts is suppressed.

  However, when a cooling fan is installed in the image forming apparatus, in order to prevent an increase in noise or an increase in power consumption due to the driving of the cooling fan, the temperature varies depending on the temperature inside the image forming apparatus or the temperature change inside the image forming apparatus. Therefore, it is necessary to optimally control the rotation speed of the cooling fan.

  In this way, in order to control the rotation speed of the cooling fan, for example, a copying machine is proposed in which the air flow rate of the cooling fan is switched in accordance with the magnification ratio of the original and the number of continuous copies (see Patent Document 1). . In this copying machine, the longer the magnification of the document is, the longer the lighting time of the exposure lamp is, the more heat is dissipated from the exposure lamp, and the temperature inside the image forming apparatus increases. Further, as the number of continuous copies increases, the temperature rise inside the image forming apparatus increases. For this reason, the copying machine is set so that the larger the document magnification, the smaller the number of sheets that have elapsed since the start of continuous copying when the air flow of the cooling fan switches from small to large.

In addition, as a cooling fan installed inside a casing of a computer, printer, acoustic device, etc., the temperature data inside the casing sensed by a temperature sensor installed inside the casing is stored in the memory, and the memory The temperature data stored in is input to the central processing unit, the heat generation capacity of the heat source inside the housing is calculated based on fuzzy theory, and the rotation speed is determined according to this heat generation capacity Variable rotation control cooling Fans have been proposed (see Patent Document 2).
JP-A-6-42494 Japanese Patent Laid-Open No. 4-372951

  However, in the image forming apparatus of Patent Document 1, the rotation speed of the cooling fan is not controlled in consideration of the temperature inside the image forming apparatus at the start of copying. For this reason, when the internal temperature of the image forming apparatus at the start of copying is low, the internal air temperature of the image forming apparatus is sufficiently lower than the target temperature that serves as a guide for switching the air volume of the cooling fan. When switching from small to large, the air flow of the cooling fan can be kept small until the internal temperature of the image forming apparatus reaches the target temperature, which increases the noise of the cooling fan and reduces power consumption. There is a problem of increasing.

  In addition, when the temperature inside the image forming apparatus is high at the start of copying, the air flow of the cooling fan necessary for suppressing the temperature rise inside the image forming apparatus cannot be obtained. There is a possibility that the temperature inside the image forming apparatus at the time of switching to the high temperature is higher than a target temperature that serves as a guide for switching the air flow of the cooling fan, that is, the inside of the image forming apparatus may be overheated.

  On the other hand, when the variable rotation control cooling fan disclosed in Patent Document 2 is installed in the image forming apparatus disclosed in Patent Document 1, the heat generation capacity of the heat generation source does not depend on the internal temperature of the image forming apparatus at the start of copying. By calculating, the rotation speed of the cooling fan can be controlled. However, if a new temperature sensor for measuring the temperature inside the image forming apparatus is newly installed inside the image forming apparatus, there is a problem that the cost of components increases by the temperature sensor and the harness connected to the temperature sensor. There is. Another problem is that a new port is required to input temperature data stored in the memory to the central processing unit, which complicates the configuration of the image forming apparatus.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a cooling fan with a simple configuration without newly adding a temperature sensor for detecting the temperature inside the image forming apparatus. Another object of the present invention is to provide an image forming apparatus capable of optimally controlling the rotation speed of the image forming apparatus.

  In order to achieve the above object, an image forming apparatus according to the present invention has a fixing roller and a heater for heating the fixing roller, and fixes toner onto a recording sheet passing through the fixing roller heated by the heater. An image forming apparatus comprising: a fixing unit to be cooled; and a cooling unit that cools the inside of the apparatus by dissipating at least heat of the fixing unit to the outside of the apparatus, wherein the cooling is performed while continuous printing of recording paper is performed. And adjusting the cooling capacity of the cooling section, estimating the temperature inside the apparatus when continuous printing of recording paper is started, and changing the timing of adjusting the cooling capacity of the cooling section according to this temperature To do.

  The image forming apparatus configured as described above includes a temperature sensor for detecting the temperature of the fixing roller, and the continuous printing of the recording paper is started from the temperature information of the temperature sensor when the continuous printing of the recording paper is started. Estimate the temperature inside the device when

  Here, there is a correlation between the temperature of the fixing roller detected by the temperature sensor and the temperature inside the image forming apparatus. That is, when the temperature of the fixing roller is low, the amount of heat released from the fixing roller is small, so the temperature inside the image forming apparatus is low. On the other hand, when the temperature of the fixing roller is high, the amount of heat released from the fixing roller is large, so that the temperature inside the image forming apparatus becomes high. In this way, the temperature inside the image forming apparatus when continuous printing of recording paper is started can be estimated from the temperature information of the temperature sensor.

  In the image forming apparatus configured as described above, an elapsed time from when the energization of the heater is stopped to when the energization of the heater is started before the continuous printing of the recording paper is started. A first time measurement unit that measures an elapsed time from when the energization to the heater is started before the continuous printing of the recording paper is started to when the energization to the heater is stopped next, The temperature inside the apparatus when continuous printing of recording paper is started is estimated from the measurement value of the first time measurement unit.

Here, the minimum value t _min of the internal temperature of the image forming apparatus is set, and the internal temperature of the image forming apparatus according to the elapsed time from when the energization to the heater is started until the energization to the heater is stopped. Measure in advance how it rises. Further, a maximum value t _max of the temperature inside the image forming apparatus is set, and the internal temperature of the image forming apparatus is set according to the elapsed time from when the energization to the heater is stopped until the energization to the heater is started next. Pre-measure how the temperature falls. Then, an elapsed time from when the energization to the heater is started to when the energization to the heater is stopped, an elapsed time from when the energization to the heater is stopped to when the energization to the heater is started, and an image A data table or a mathematical expression representing the relationship with the temperature inside the forming apparatus is created and stored in the image forming apparatus. Also, the initial value of the temperature inside the image forming apparatus is stored in the image forming apparatus in advance.

  As described above, the initial value of the internal temperature of the image forming apparatus, the elapsed time from when the energization to the heater is started by the first time measurement unit to when the energization to the heater is stopped, and the energization to the heater are stopped. The internal temperature of the image forming apparatus when the continuous printing of the recording paper is started can be estimated from the measured value of the elapsed time from when the heater is energized to when the heater is next energized.

  Each of the image forming apparatuses described above includes a date measuring unit that measures the date, and estimates the temperature inside the apparatus when continuous printing of recording paper is started according to the measurement value of the date measuring unit. It does not matter.

  Here, since the inside of the image forming apparatus is easily affected by the heat outside the image forming apparatus, the temperature changes according to the season. For this reason, the temperature inside the image forming apparatus when continuous printing of recording paper is started every season is measured in advance, and a data table or a mathematical expression representing the relationship between the season and the temperature inside the image forming apparatus is created. By storing in the image forming apparatus, it is possible to estimate the temperature inside the image forming apparatus when continuous printing of recording paper is started from the measurement value of the date measurement unit.

  Each of the image forming apparatuses described above includes a light-emitting unit and an exposure unit that emits laser light from the light-emitting unit toward the photosensitive drum, and the cooling unit dissipates heat from the exposure unit to the outside of the apparatus. By doing so, the inside of the apparatus may be cooled.

  At this time, the elapsed time from when the power supply to the light emitting unit is stopped before the continuous printing of the recording paper is started until the next time the power supply to the light emitting unit is started, and the continuous printing of the recording paper is started. A second time measuring unit that measures an elapsed time from when the power supply to the light emitting unit is started to when the power supply to the light emitting unit is stopped before being measured, and the measured value of the second time measuring unit From this, the temperature inside the apparatus when continuous printing of recording paper is started is estimated.

Here, the minimum value t _min of the temperature inside the image forming apparatus is set, and the inside of the image forming apparatus is set according to the elapsed time from the start of energization to the light emitting section until the energization to the light emitting section is stopped. Measure in advance how the temperature rises. In addition, the maximum value t _max of the internal temperature of the image forming apparatus is set, and the image forming apparatus has an elapsed time from when the power supply to the light emitting unit is stopped to when the power supply to the light emitting unit is started next. Pre-measure how the internal temperature drops. And the elapsed time from the start of energization to the light emitting unit until the energization to the light emitting unit is stopped and the elapsed time from the start of energization to the light emitting unit to the next start of energization to the light emitting unit A data table or a mathematical expression representing the relationship between the time and the temperature inside the image forming apparatus is created and stored in the image forming apparatus. Also, the initial value of the temperature inside the image forming apparatus is stored in the image forming apparatus in advance.

  As described above, the initial value of the temperature inside the image forming apparatus, the elapsed time from the start of energization to the light emitting unit by the second time measurement unit until the energization to the light emitting unit is stopped, The temperature inside the image forming apparatus when continuous printing of recording paper is started can be estimated from the measured value of the elapsed time from when the energization is stopped to when the energization of the light emitting unit is started next. it can.

  During the operation of the image forming apparatus, not only the light emitting unit such as a semiconductor laser but also a motor for driving the polygon mirror generates heat in the exposure unit. Therefore, the elapsed time from when the energization to the motor is started to when the energization to the motor is stopped and the elapsed time from when the energization to the motor is stopped to when the energization to the motor is started next are the second time. The temperature may be measured by the time measuring unit, and the temperature inside the image forming apparatus when the recording paper is printed may be estimated from the measured value.

  In each of the image forming apparatuses described above, the cooling unit is a cooling fan, and when the continuous print number of recording papers after starting printing reaches a predetermined value, the rotation speed of the cooling fan is switched to change the rotation speed of the cooling fan. While adjusting the cooling capacity of the cooling section, the timing for adjusting the cooling capacity of the cooling section may be set according to the number of continuous prints of the recording paper.

  In the image forming apparatus configured as described above, when continuous printing of recording paper is started, heat is released from the recording paper, and the temperature inside the image forming apparatus increases as the number of continuous printing sheets of recording paper increases. I will do it. Therefore, when the number of continuous prints of the recording paper reaches a predetermined value, it is determined that the temperature inside the image forming apparatus has risen to some extent, and the rotation speed of the cooling fan is switched. Further, the timing for switching the rotation speed of the cooling fan is set according to the number of continuous prints of the recording paper according to the temperature inside the image forming apparatus when the continuous printing of the recording paper is started. For example, the higher the internal temperature of the image forming apparatus when the continuous printing of the recording paper is started, the smaller the number of continuous printing sheets of the recording paper until the timing at which the rotation speed of the cooling fan is switched is set. .

  In each of the image forming apparatuses described above, the cooling unit is a cooling fan, and when the continuous printing time of recording paper after starting printing reaches a predetermined value, the rotation speed of the cooling fan is switched to change the rotation speed of the cooling fan. While adjusting the cooling capacity of the cooling section, the timing for adjusting the cooling capacity of the cooling section may be set by the continuous printing time of the recording paper.

  In the image forming apparatus configured as described above, when continuous printing of recording paper is started, heat is released from the recording paper, and the temperature inside the image forming apparatus increases as the continuous printing time of the recording paper increases. I will do it. Therefore, when the continuous printing time of the recording paper reaches a predetermined value, it is determined that the temperature inside the image forming apparatus has risen to some extent, and the rotation speed of the cooling fan is switched. Further, the timing for switching the rotation speed of the cooling fan is set according to the continuous printing time of the recording paper according to the temperature inside the image forming apparatus when the continuous printing of the recording paper is started. For example, the higher the internal temperature of the image forming apparatus when the continuous printing of the recording paper is started, the shorter the continuous printing time of the recording paper until the timing at which the rotation speed of the cooling fan is switched is set. .

  Further, in each of the image forming apparatuses described above, a charger that generates an electric charge for applying an electric action to the photosensitive drum, and a discharge product discharge fan that discharges a discharge product generated by discharge of the charger to the outside of the apparatus. And the elapsed time from when the energization of the charger is stopped before the continuous printing of the recording paper is started to when the energization of the charger is started next, and before the continuous printing of the recording paper is started. And a third time measuring unit for measuring an elapsed time from when the energization to the charger is started to when the energization to the charger is stopped, and while the recording paper is continuously printed, Discharge generation inside the apparatus when the rotation speed of the discharge product discharge fan is switched and continuous printing of recording paper is started from the measurement value of the third time measurement unit The guess concentration may be as to change the timing for switching the rotation speed of the discharge product discharge fan depending on the concentration of the discharge products.

Here, the minimum value _Xmin of the concentration of the discharge product inside the image forming apparatus is set, and the inside of the image forming apparatus is set according to the elapsed time from when the energization to the charger is started until the energization to the charger is stopped. It is measured in advance how the concentration of the discharge product increases. In addition, the maximum value X _max of the concentration of the discharge product inside the image forming apparatus is set, and the image forming apparatus is set according to the elapsed time from when the energization to the charger is stopped until the next energization to the charger is started. It is measured in advance how the concentration of the internal discharge product decreases. Then, an elapsed time from when the energization to the charger is started to when the energization to the charger is stopped, an elapsed time from when the energization to the charger is stopped until the next energization to the charger, and an image A data table or a mathematical expression representing the relationship with the concentration of the discharge product inside the forming apparatus is created and stored in the image forming apparatus. The initial value of the concentration of the discharge product inside the image forming apparatus is stored in the image forming apparatus in advance.

  As described above, the initial value of the concentration of the discharge product in the image forming apparatus, the elapsed time from the start of energization of the charger to the charger by the third time measurement unit, and the charging to the charger From the measured value of the elapsed time from when the energization is stopped until the next energization to the charger is started, the concentration of the discharge product inside the image forming apparatus when continuous printing of the recording paper is started is estimated be able to.

  The charger includes a charger for transferring the toner adhering to the surface of the photosensitive drum to the recording paper, a charger for separating the toner transferred to the recording paper from the surface of the photosensitive drum, and the toner being transferred to the recording paper. For example, a charger for discharging the toner remaining on the surface of the photosensitive drum after being discharged, or a charger for discharging the surface of the photosensitive drum after the toner has been transferred to the recording paper.

Examples of the discharge product generated by the discharge of the charger include ozone (O ₃ ) and nitrogen oxide (NO _x ).

  At this time, the rotation speed of the discharge product discharge fan is switched and the rotation speed of the discharge product discharge fan is switched when the number of continuous prints of the recording paper after starting printing reaches a predetermined value. Is set according to the number of continuous prints of recording paper.

  In the image forming apparatus configured as described above, when continuous printing of the recording paper is started, corona discharge is performed from the charger toward the photosensitive drum, and as the number of continuous printing sheets of the recording paper increases, the inside of the image forming apparatus is increased. The concentration of the discharge product increases. Therefore, when the number of continuous prints of the recording paper reaches a predetermined value, it is determined that the concentration of the discharge product in the image forming apparatus has increased to some extent, and the rotation speed of the discharge product discharge fan is switched. The timing for switching the rotational speed of the discharge product discharge fan is set according to the number of continuous prints of the recording paper according to the density of the discharge product inside the image forming apparatus when continuous printing of the recording paper is started. For example, the higher the density of the discharge product inside the image forming apparatus when the continuous printing of the recording paper is started, the higher the number of continuous printings of the recording paper until the timing at which the rotation speed of the discharge product discharge fan switches is reached. Set to be shorter.

  At this time, when the continuous printing time of the recording paper after starting printing reaches a predetermined value, the rotation speed of the discharge product discharge fan is switched, and the rotation speed of the discharge product discharge fan is changed. The switching timing is set according to the continuous printing time of the recording paper.

  In the image forming apparatus configured as described above, when continuous printing of the recording paper is started, corona discharge is performed from the charger toward the photosensitive drum, and the continuous printing time of the recording paper increases. The concentration of the discharge product increases. Therefore, when the continuous printing time of the recording paper reaches a predetermined value, it is determined that the concentration of the discharge product in the image forming apparatus has increased to some extent, and the rotation speed of the discharge product discharge fan is switched. The timing for switching the rotation speed of the discharge product discharge fan is set according to the continuous printing time of the recording paper according to the density of the discharge product inside the image forming apparatus when continuous printing of the recording paper is started. For example, the continuous printing time of the recording paper until reaching the timing at which the rotation speed of the discharge product discharge fan switches as the concentration of the discharge product inside the image forming apparatus when the continuous printing of the recording paper is started is higher Set to be shorter.

  According to the present invention, the cooling capacity of the cooling unit is always constant by setting the timing for adjusting the cooling capacity of the cooling unit according to the temperature inside the image forming apparatus when continuous printing of recording paper is started. As compared with the case of setting to 1, the noise generated in the cooling unit and the power consumption of the image forming apparatus can be reduced. Further, for example, a temperature sensor for detecting the internal temperature of the image forming apparatus by estimating the internal temperature of the image forming apparatus from the temperature information of a temperature sensor that detects the temperature of a general fixing roller, There is no need to newly add a harness connected to the temperature sensor to the image forming apparatus. Therefore, the component cost of the image forming apparatus can be reduced, and the configuration of the image forming apparatus can be simplified.

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

Embodiment 1 of the Invention
As shown in FIG. 1, the image forming apparatus according to the present embodiment reverses the main body 1 and the recording paper conveyed from the main body 1 in order to perform double-sided printing of the recording paper, and returns to the main body 1 again. And a reversing unit 2 that conveys the recording paper, and is configured to be capable of single-sided printing or double-sided printing of recording paper. As shown in FIGS. 1 and 2, the main body 1 is irradiated with laser light on the photosensitive drum 3, a charging device 10 that charges the entire surface of the photosensitive drum 3, and the surface of the photosensitive drum 3. The exposure device 20, the developing device 30 that performs development by attaching the toner 31 to the portion of the surface of the photosensitive drum 3 irradiated with the laser light, and the toner 31 that adheres to the surface of the photosensitive drum 3 are transferred to the recording paper The transfer device 40, the fixing device 50 for fixing the toner 31 transferred onto the recording paper to the recording paper, and the heat generated in the fixing device 50 to the outside of the image forming device to cool the inside of the image forming device. A cooling fan 60 is installed as a cooling unit.

  As shown in FIG. 1, the main body 1 is fed with a paper feed cassette 70, a paper feed roller 71 that feeds recording paper from the paper feed cassette 70, and a recording paper fed from the paper feed roller 71. A conveyance roller 72, a pair of registration rollers 73 that correct the orientation of the recording paper that has passed through the conveyance roller 72 and adjust the timing at which the recording paper is conveyed, and the recording paper from the pair of registration rollers 73 to the photosensitive drum 3. At the same time, the paper passes through the conveyance guide 74 for conveying the recording paper that has passed through the photosensitive drum 3 to the fixing device 50, the discharge direction switching guide 75 for switching the discharge direction of the recording paper that has passed through the fixing device 50, and the discharge direction switching guide 75. A paper discharge roller 76 for discharging the recording paper to the outside of the image forming apparatus and a recording paper discharged from the paper discharge roller 76 to the outside of the image forming apparatus are stored. A paper discharge tray 77 is provided for.

  Further, as shown in FIG. 1, the reversing unit 2 is provided with a conveyance roller 78 for conveying the recording paper printed on one side after passing through the discharge direction switching guide 75, and a conveyance roller 78 between the conveyance rollers 78 and recording. A transport unit 79 that transports the paper downward, a lower tray 80 to which the recording paper that has passed through the transport unit 79 is temporarily fed, a reversing roller 81 that reverses the recording paper fed from the lower tray 80, and a plurality of media between them. And an upper tray 82 for conveying the recording paper that has passed through the reverse roller 81 toward the main body 1.

  Further, as shown in FIG. 2, the image forming apparatus calculates the temperature inside the image forming apparatus based on the temperature information of the temperature sensor 54 that detects the temperature of the fixing roller 51 and outputs the calculation result to the control device 92. A power supply device that supplies power to the arithmetic processing device 90 that outputs, the cooling fan 60, the charging device 10, the exposure device 20, the developing device 30, the transfer device 40, the fixing device 50, the arithmetic processing device 90, and the control device 92. 91 and a control device 92 that controls the operation of each device installed inside the image forming apparatus. The image forming apparatus sequentially performs each process of a charging process, an exposure process, a development process, a transfer process, and a fixing process.

  In the image forming apparatus having such a configuration, first, the charging device 10 includes the charging roller 11 shown in FIG. 1. The charging roller 11 is installed at a position close to the photosensitive drum 3, and charged charged. The surface of the photosensitive drum 3 is negatively charged by the discharge of the roller 11.

  As shown in FIG. 1, the exposure apparatus 20 is driven by a semiconductor laser (not shown) as a light emitting unit that emits laser light and a mirror motor (not shown) and emits laser light emitted from the semiconductor laser. A polygon mirror (not shown) for deflecting in the main scanning direction is provided. In the exposure process, the exposure apparatus 20 reflects the laser light emitted from the semiconductor laser by the polygon mirror and deflects it in the main scanning direction, and irradiates the photosensitive drum 3 with the laser light reflected by the polygon mirror. An electrostatic latent image is formed on the drum 3 by positively charging the portion irradiated with the laser beam.

  As shown in FIG. 1, the developing device 30 is provided in the vicinity of the photosensitive drum 3, and includes a developing roller 32 for transporting the toner 31 to the photosensitive drum 3, and the toner 31 is provided inside the developing device 30. Is housed. The developing device 30 performs development by attaching toner 31 to the electrostatic latent image formed on the surface of the photosensitive drum 3.

  The transfer device 40 includes a transfer roller 41 shown in FIG. 1, and a nip portion is formed between the transfer roller 41 and the photosensitive drum 3 so as to sandwich the recording paper. When the recording paper passes through the nip portion, the transfer device 40 transfers the toner 31 to the recording paper by attracting the toner 31 attached to the photosensitive drum 3 to the positively charged transfer roller 41.

  Further, as shown in FIG. 1, the fixing device 50 includes a fixing roller 51, a fixing heater 52 that is installed inside the fixing roller 51 and heats the fixing roller 51, and a pressure roller 53. A nip portion is formed between the fixing roller 51 and the pressure roller 53 to sandwich the recording paper. Then, when the recording paper passes through the nip portion, the fixing device 50 dissolves the toner 31 of the recording paper by the fixing roller 51 and applies pressure to the recording paper by the pressure roller 53 to remove the toner 31 from the recording paper. To settle.

  As shown in FIG. 2, the fixing device 50 includes a temperature sensor 54 that detects the temperature of the fixing roller 51. Each of the fixing heater 52 and the temperature sensor 54 is connected to a control device 92. When the fixing device 50 is driven and controlled by the control device 92, the temperature sensor 54 detects the temperature of the fixing roller 51 and the temperature information detected by the temperature sensor 54 is input to the control device 92. The control device 92 controls the temperature of the fixing heater 52 based on this temperature information.

  In the image forming apparatus configured as described above, when one of the one-sided printing mode for printing only one side of the recording paper and the double-sided printing mode for printing on both sides of the recording paper is instructed by the user, The conforming information is input to the arithmetic processing unit 90 shown in FIG. As shown in FIG. 2, a temperature sensor 54 that detects the temperature of the fixing roller 51 is connected to the arithmetic processing unit 90, and temperature information of the temperature sensor 54 is input to the arithmetic processing unit 90. The arithmetic processing unit 90 includes a program for calculating the temperature inside the image forming apparatus from the temperature information of the temperature sensor 54.

  Here, there is a correlation between the temperature of the fixing roller 51 detected by the temperature sensor 54 and the temperature inside the image forming apparatus. That is, when the temperature of the fixing roller 51 is low, the amount of heat released from the fixing roller 51 is small, so the temperature inside the image forming apparatus is low. On the other hand, when the temperature of the fixing roller 51 is high, since the amount of heat released from the fixing roller 51 is large, the temperature inside the image forming apparatus becomes high. As described above, the temperature inside the image forming apparatus can be estimated from the temperature information of the temperature sensor 54, and the temperature inside the image forming apparatus is calculated by executing the program provided in the arithmetic processing unit 90. be able to.

  Further, during operation of the image forming apparatus, the recording paper is heated by the fixing roller 51 in the fixing process, and the internal temperature of the image forming apparatus rises due to heat radiation from the recording paper. For this reason, in order to prevent the inside of the image forming apparatus from being overheated, the cooling fan 60 is driven at a predetermined rotational speed to dissipate the heat of the fixing roller 51 to the outside of the image forming apparatus. Therefore, it is necessary to keep the temperature inside the image forming apparatus lower than the upper limit value of a preset range so as not to cause a problem in the electronic components inside the image forming apparatus.

  Therefore, the arithmetic processing unit 90 shown in FIG. 2 includes a counter (not shown) that measures the number of continuous prints of recording paper. Then, the arithmetic processing unit 90 calculates the internal temperature of the image forming apparatus when the continuous printing of the recording paper is started in the double-sided printing mode, and after the continuous printing of the recording paper is started from this temperature. The number of continuous prints of the recording paper until the timing at which the rotation speed of the cooling fan 60 is switched is set in anticipation of the temperature change in the image forming apparatus. Then, the arithmetic processing unit 90 outputs a signal to the control device 92 for switching the rotation speed of the cooling fan 60 from low speed to high speed when the counter measurement value reaches the set number of continuous printing sheets. As described above, when the rotation speed of the cooling fan 60 is switched from the low speed to the high speed, the air volume of the cooling fan 60 is increased, and the cooling capacity of the cooling fan 60 is improved.

  Specifically, when the internal temperature of the image forming apparatus when the continuous printing of the recording paper calculated by the arithmetic processing unit 90 is started is low, the preset upper limit value of the internal temperature of the image forming apparatus and the recording are recorded. There is a large difference from the temperature inside the image forming apparatus when continuous printing of paper is started. For this reason, the time until the control signal for switching the rotation speed of the cooling fan 60 from the low speed to the high speed is output from the control device 92 to the cooling fan 60 after the continuous printing of the recording paper is started is increased. Is set. That is, the counter measurement value is set to increase until the timing for switching the rotation speed of the cooling fan 60 is reached.

  On the other hand, when the internal temperature of the image forming apparatus when the continuous printing of the recording paper calculated by the arithmetic processing unit 90 is started is high, the preset upper limit value of the internal temperature of the image forming apparatus and the recording paper A difference from the temperature inside the image forming apparatus when continuous printing is started is small. For this reason, the time until the control signal for switching the rotation speed of the cooling fan 60 from the low speed to the high speed is output from the control device 92 to the cooling fan 60 after the continuous printing of the recording paper is started is shortened. Is set. That is, the counter measurement value until the timing for switching the rotation speed of the cooling fan 60 is reached is set to be small.

  2 is output to the control device 92 shown in FIG. 2, and a control signal for switching the rotation speed of the cooling fan 60 from the low speed to the high speed is output from the control device 92 to the cooling fan 60. 2 has a built-in voltage control circuit (not shown), and a voltage necessary for rotating the cooling fan 60 at a predetermined rotational speed is applied from the voltage control circuit to the cooling fan 60. It is done. That is, the rotational speed of the cooling fan 60 is controlled by the voltage value generated by the voltage control circuit. This voltage control circuit can be realized by using a PWM (Pulse Width Modulator) method.

  In this image forming apparatus, the rotation speed of the cooling fan 60 is set in two stages, that is, low speed and high speed. However, the rotation speed of the cooling fan 60 is not limited to this, and the rotation speed of the cooling fan 60 is low, medium, and high speed. May be set to three stages, or more stages than this. Alternatively, a function for calculating the optimum rotation speed of the cooling fan 60 from the temperature inside the image forming apparatus when continuous printing of recording paper is started is incorporated in the arithmetic processing unit 90, and the optimum cooling determined by this function is incorporated. The cooling fan 60 may be controlled based on the value of the rotational speed of the fan 60. This function may be configured such that the rotational speed of the cooling fan 60 increases at a constant rate as the temperature inside the image forming apparatus increases, or the temperature inside the image forming apparatus may be It may be configured such that the rate of increase in the rotational speed of the cooling fan 60 increases as it rises.

  Further, in this image forming apparatus, a counter (not shown) for measuring the elapsed time from the start of continuous printing of recording paper is installed in the arithmetic processing unit 90 in place of the counter for measuring the continuous printing number of recording paper. May be. In the image forming apparatus configured as described above, the arithmetic processing unit 90 calculates the internal temperature of the image forming apparatus when continuous printing of recording paper is started in the double-sided printing mode, and records from this temperature. A temperature change inside the image forming apparatus after the start of continuous printing of paper is predicted, and the continuous printing time of recording paper until the timing at which the rotation speed of the cooling fan 60 is switched is set. Then, the arithmetic processing unit 90 outputs a signal to the control device 92 for switching the rotation speed of the cooling fan 60 from the low speed to the high speed when the recording paper continuous printing time for which the measurement value of the counter is set is reached.

  Further, in this image forming apparatus, not only in the double-sided printing mode but also in the single-sided printing mode, the number of continuous printing sheets or the continuous printing time until the rotational speed of the cooling fan 60 is switched as described above is set, and the counter The rotation speed of the cooling fan 60 may be switched from the low speed to the high speed when the continuous print number or the continuous print time of the recording paper for which the measured value is set is reached. Here, in the single-sided printing mode, since the recording paper having heat is transported in a shorter distance than in the double-sided printing mode, the amount of heat released from the recording paper is smaller than in the double-sided printing mode. Therefore, in the single-sided printing mode, the continuous printing number or continuous printing time until the timing at which the rotation speed of the cooling fan 60 is switched is set to be longer than in the double-sided printing mode. That is, in the single-sided printing mode, the measurement value of the counter until reaching the timing for switching the rotation speed of the cooling fan 60 is set to be larger than in the double-sided printing mode.

-Operation of image forming apparatus-
The operation of the image forming apparatus will be described with reference to FIGS.

  As shown in FIG. 2, when the power of the image forming apparatus is turned on, the cooling fan 60, the charging device 10, the exposure device 20, the developing device 30, the transfer device 40, the fixing device 50, the arithmetic processing device 90, the power supply device 91, In addition, power is supplied to each of the control device 92 and a control signal from the control device 92, and the cooling fan 60, the charging device 10, the exposure device 20, the developing device 30, the transfer device 40, the fixing device 50, and the arithmetic processing device. 90 are respectively controlled. Therefore, in the main body 1 of the image forming apparatus shown in FIG. 1, the above-described charging process, exposure process, development process, transfer process, and fixing process are sequentially performed.

  Specifically, in the main body 1 of the image forming apparatus, as indicated by the solid line arrow in FIG. 1, the recording paper is sent out from the paper feeding cassette 70 by the paper feeding roller 71 and is sent out from the paper feeding cassette 70. Is conveyed to the conveyance roller 72. Then, the recording paper that has passed through the transport roller 72 is corrected in its orientation when passing between the pair of registration rollers 73 and the transport timing to the photosensitive drum 3 is adjusted. It is sent to the nip portion between the photosensitive drum 3 and the transfer roller 41.

  When the recording paper is conveyed toward the photosensitive drum 3 in this way, first, the charging device 10 charges the entire surface of the photosensitive drum 3 by discharging the charging roller 11 in the charging process. Then, in the exposure process, the exposure device 20 reflects the laser light emitted from the semiconductor laser by the polygon mirror and deflects it in the main scanning direction, and irradiates the photosensitive drum 3 with the laser light reflected by the polygon mirror. An electrostatic latent image is formed in this portion by positively charging the portion irradiated with the laser beam among the three.

  Next, the developing device 30 conveys the toner 31 charged in the developing process by the developing roller 32 so that the toner 31 adheres to the electrostatic latent image formed on the surface of the photosensitive drum 3 and develops. Subsequently, the transfer device 40 transfers the toner 31 attached to the surface of the photosensitive drum 3 onto a recording sheet that passes through the nip portion between the photosensitive drum 3 and the transfer roller 41 in the transfer process. Then, the recording paper on which the toner 31 is transferred in the transfer process is sent to the nip portion between the fixing roller 51 and the pressure roller 53 in the fixing device 50 through the conveyance guide 74.

  Further, when the control signal output from the control device 92 to the fixing heater 52 is turned ON, the fixing heater 52 is energized to heat the fixing heater 52, and the fixing heater 52 stabilizes the toner 31 on the recording paper. Then, the fixing roller 51 is heated to a temperature at which it can be fixed. Then, the fixing device 50 dissolves the toner 31 of the recording paper that passes through the nip portion between the fixing roller 51 and the pressure roller 53 in the fixing process, and applies pressure to the recording paper by the pressure roller 53. 31 is fixed on the recording paper. In the single-sided printing mode, the discharge direction switching guide 75 is switched to the direction indicated by the solid line in FIG. 1, and the recording paper on which the toner 31 is fixed in the fixing process is switched to the discharge direction as indicated by the solid line arrow in FIG. After passing through the guide 75, the paper is discharged to the outside of the image forming apparatus by the paper discharge roller 76 and discharged to the paper discharge tray 77.

  On the other hand, in the duplex printing mode, the discharge direction switching guide 75 is switched to the direction indicated by the broken line in FIG. 1, and the recording paper on which the toner 31 has been fixed in the fixing step is switched as indicated by the broken line arrow in FIG. After passing through the guide 75, it is conveyed to the reversing unit 2 of the image forming apparatus. In the reversing unit 2 of the image forming apparatus, the recording paper is conveyed by the conveying roller 78 to the conveying unit 79, and then is once sent to the lower tray 80 through the reversing roller 81. The recording sheet sent to the lower tray 80 is conveyed again to the reversing roller 81, and the printing surface is reversed when passing through the reversing roller 81. The recording paper that has passed through the reversing roller 81 is conveyed on the upper tray 82 by a plurality of conveying rollers 78, and is fed again to the main body 1 of the image forming apparatus.

  The recording paper that has been re-fed to the main body 1 of the image forming apparatus is conveyed to the pair of registration rollers 73 through the conveyance roller 72, and then conveyed to the photosensitive drum 3 through the conveyance guide 74. In the main body 1 of the image forming apparatus, the above-described charging process, exposure process, development process, transfer process, and fixing process are sequentially performed. At this time, since the printing surface of the recording paper is reversed by reversing the recording paper by the reversing roller 81, printing is performed on the surface opposite to the surface of the recording paper that has already been printed. Then, the recording paper on which the toner 31 is fixed in the fixing process passes through the discharge direction switching guide 75 as indicated by the solid line arrow in FIG. 1 when the discharge direction switching guide 75 is switched in the direction indicated by the solid line in FIG. After that, the paper is discharged to the outside of the image forming apparatus by the paper discharge roller 76 and discharged to the paper discharge tray 77.

  In the image forming apparatus that performs such an operation, a switching operation of the rotation speed of the cooling fan 60 when the recording paper is continuously printed will be described in detail below. At this time, the rotational speed of the cooling fan 60 is always kept constant in the single-sided printing mode, and the rotational speed of the cooling fan 60 is switched during the continuous printing in the double-sided printing mode. Further, as described above, the timing for switching the rotation speed of the cooling fan 60 is based on the continuous printing number of recording sheets and the continuous printing time of recording sheets. Assume that the timing for switching the rotation speed of the cooling fan 60 is determined.

FIG. 3 shows the relationship between the continuous print number of recording paper and the temperature inside the image forming apparatus. In FIG. 3, the ● mark represents the single-sided printing mode, and the ■ mark represents the double-sided printing mode. Further, the upper limit value of the temperature range inside the image forming apparatus set in advance so as not to cause a problem in the electronic components and the like inside the image forming apparatus is assumed to be t ₁ .

  First, when the user designates the single-sided printing mode, a control signal for setting the rotational speed of the cooling fan 60 to, for example, 3000 rpm is sent from the control device 90 to the cooling fan 60 regardless of the value measured by the counter for the continuous printing number of recording sheets. Is output. At this time, a voltage for setting the rotational speed of the cooling fan 60 to 3000 rpm is supplied from the power supply control circuit of the power supply device 91 to the cooling fan 60. Then, as shown in FIG. 3, as the measured value of the counter increases, the internal temperature of the image forming apparatus rises due to heat radiation from the recording paper, and when the measured value of the counter reaches a certain level, a subsequent image is displayed. The temperature inside the forming apparatus is kept substantially constant.

  On the other hand, when the user designates the double-sided printing mode, a control signal for setting the rotation speed of the cooling fan 60 to, for example, 3000 rpm is output from the control device 90 to the cooling fan 60. At this time, a voltage for setting the rotational speed of the cooling fan 60 to 3000 rpm is supplied from the power supply control circuit of the power supply device 91 to the cooling fan 60. Then, as shown in FIG. 3, as the measurement value of the counter increases, the temperature inside the image forming apparatus rises due to heat radiation from the recording paper.

In this double-sided printing mode, the amount of heat released from the recording paper is larger than in the single-sided printing mode because the distance that the recording paper having heat is transported is longer than in the single-sided printing mode. The rate of temperature increase is greater than the rate of temperature increase inside the image forming apparatus in the single-sided printing mode. For this reason, in the duplex printing mode, the rotation speed of the cooling fan 60 is controlled by a counter in order to prevent the temperature inside the image forming apparatus from rising to a preset upper limit value t ₁ during the operation of the image forming apparatus. It is necessary to change according to the measured value of the continuous print number of recording paper.

  Therefore, when the user designates the duplex printing mode, the temperature sensor 54 detects the temperature of the fixing roller 51, and the temperature information of the temperature sensor 54 is input to the arithmetic processing unit 90. Further, the arithmetic processing unit 90 calculates the temperature inside the image forming apparatus when continuous printing of recording paper is started based on the temperature information of the temperature sensor 54. Then, a signal indicating that the rotation speed of the cooling fan 60 is switched from the control device 92 according to the temperature inside the image forming apparatus when the continuous printing of the recording paper calculated by the arithmetic processing unit 90 is started is a cooling fan. The timing to be output to 60 is set. This timing is set based on the relationship between the internal temperature of the image forming apparatus and the number of continuous prints of the recording paper, which are measured in advance during manufacture or experiment.

  Specifically, the internal temperature of the image forming apparatus when the continuous printing of the recording paper is started is variously changed, and the internal temperature of the image forming apparatus is set to a temperature at which the rotation speed of the cooling fan 60 is switched. The number of continuous prints of recording paper until it reaches is measured in advance and determined. A data table or a mathematical expression representing the relationship between the temperature inside the image forming apparatus when continuous printing of recording paper is started and the number of continuous printing sheets until reaching the timing for switching the rotation speed of the cooling fan 60 Is stored in the arithmetic processing unit 90. The data table and the mathematical formula indicate that the number of continuous prints of the recording paper until the timing for switching the rotation speed of the cooling fan 60 is reached as the internal temperature of the image forming apparatus increases when the continuous printing of the recording paper is started. Set to be less.

When the arithmetic processing unit 90 is configured in this way, as shown in FIG. 3, when the internal temperature of the image forming apparatus when the continuous printing of recording paper is started becomes, for example, t ₂ , the above data table or mathematical expression is used. The continuous print number of recording sheets until the temperature inside the image forming apparatus reaches a temperature t ₃ which is a timing for switching the rotation speed of the cooling fan 60 is set to S ₁ . At this time, when continuous printing of the recording paper is started, the cooling fan 60 operates at a rotational speed of 3000 rpm. Thereafter, when the measured value of the counter reaches S ₁ sheet, a signal for switching the rotation speed of the cooling fan 60 to, for example, 3600 rpm is output from the arithmetic processing unit 90 to the control unit 92. Therefore, a voltage for setting the rotation speed of the cooling fan 60 to 3600 rpm is supplied to the cooling fan 60 from the power supply control circuit of the power supply device 91.

Then, when the measured value of the counter reaches S ₁ sheet, the temperature inside the image forming apparatus rises to t ₃ lower than the upper limit value t ₁ , and at this time, the rotation speed of the cooling fan 60 reaches 3600 rpm. Therefore, the rate of increase in the temperature inside the image forming apparatus thereafter becomes smaller than that in the case where the rotation speed of the cooling fan 60 is always 3000 rpm.

  As described above, the data table representing the relationship between the temperature inside the image forming apparatus when continuous printing of the recording paper is started and the number of continuous printing sheets until reaching the timing for switching the rotation speed of the cooling fan 60 or By creating mathematical formulas and storing them in the arithmetic processing unit 90, it is necessary to use them to change the rotation speed of the cooling fan 60 from the temperature inside the image forming apparatus when continuous printing of recording paper is started. The measured value of the counter can be obtained.

Further, by configuring the arithmetic processing device in this way, when the internal temperature of the image forming apparatus when continuous printing of recording paper is started is lower than t _{2, the} timing for switching the rotation speed of the cooling fan 60 is switched. measured value of the counter to reach is set to be larger than _one S. On the other hand, when the internal temperature of the image forming apparatus when the continuous printing of the recording sheet is started is higher than t _2, the measurement value of the counter to reach the timing of switching the rotation speed of the cooling fan 60 is higher than _one S Is set to be less.

-Effect of Embodiment 1-
According to this embodiment, according to the temperature inside the image forming apparatus when continuous printing of recording paper is started, the number of continuous printing sheets of recording paper until the timing at which the rotation speed of the cooling fan 60 is switched is determined. By setting, the noise of the cooling fan 60 and the power consumption of the image forming apparatus can be surely reduced as compared with the case where the rotation speed of the cooling fan 60 is always set constant. Further, a temperature sensor for detecting the internal temperature of the image forming apparatus by estimating the internal temperature of the image forming apparatus from the temperature information of the temperature sensor 54 that detects the temperature of the fixing roller 51 that is generally used. There is no need to newly add a harness connected to the temperature sensor to the image forming apparatus. Therefore, the component cost of the image forming apparatus can be reduced, and the configuration of the image forming apparatus can be simplified.

<< Embodiment 2 of the Invention >>
In the second embodiment of the present invention, the configuration of the image forming apparatus of the first embodiment is changed. Here, the difference between the present embodiment and the first embodiment will be described.

  In the image forming apparatus according to the present exemplary embodiment, the elapsed time from when the energization to the fixing heater 52 is stopped to when the energization to the fixing heater 52 is started next and after the energization to the fixing heater 52 is started. A counter (not shown) as a first time measuring unit that measures an elapsed time until the energization to 52 is stopped is installed in the arithmetic processing unit 90 shown in FIG.

  Then, the measured value of the elapsed time from when the energization to the fixing heater 52 measured by the counter is stopped until the next energization to the fixing heater 52 is started and the fixing after the energization to the fixing heater 52 is started. The measured value of the elapsed time until the energization of the heater 52 is stopped is stored in the arithmetic processing unit.

Here, the minimum value t _min of the internal temperature of the image forming apparatus is set, and the image forming apparatus according to the elapsed time from when the energization to the fixing heater 52 is started until the energization to the fixing heater 52 is stopped. It is measured in advance how the temperature of the inside rises. Further, the maximum value t _max of the temperature inside the image forming apparatus is set, and image formation is performed according to the elapsed time from when the energization to the fixing heater 52 is stopped until the energization to the fixing heater 52 is started next. It is measured in advance how the temperature inside the device falls.

  Then, the elapsed time from when the energization to the fixing heater 52 is started until the energization to the fixing heater 52 is stopped, and after the energization to the fixing heater 52 is stopped, the energization to the fixing heater 52 is started next. A data table or a mathematical expression showing the relationship between the elapsed time until the image forming time and the temperature inside the image forming apparatus is created and stored in the arithmetic processing unit 90.

  Further, the temperature inside the image forming apparatus is measured at the time of manufacturing the image forming apparatus, and the measured temperature inside the image forming apparatus is stored as an initial value in the arithmetic processing unit 90 at the time of manufacturing the image forming apparatus.

  As described above, the initial value of the temperature inside the image forming apparatus, the elapsed time from when the energization to the fixing heater 52 is started until the energization to the fixing heater 52 is stopped, and the energization to the fixing heater 52 are stopped. The internal temperature of the image forming apparatus when printing on the recording paper can be estimated from the elapsed time until the energization of the fixing heater 52 is started next.

  By configuring the image forming apparatus in this way, the measured value of the elapsed time from when the energization to the fixing heater 52 by the counter is stopped until the energization to the fixing heater 52 is started next, and the fixing heater 52 are configured. When the measured value of the elapsed time from when the energization to the fixing heater 52 is stopped is input to the arithmetic processing unit 90, the image forming apparatus when the continuous printing of the recording paper is started The temperature inside can be calculated.

  Further, the measured value of the elapsed time from when the energization to the fixing heater 52 by the counter is stopped until the next energization to the fixing heater 52 and the energization to the fixing heater 52 are started to the fixing heater 52. The timing at which the rotation speed of the cooling fan 60 is switched according to the temperature inside the image forming apparatus when the continuous printing of the recording paper calculated from the measured value of the elapsed time until the energization is stopped is started. The measured value of the number of continuous prints of the recording paper by the counter until it reaches is set.

  Further, during operation of the image forming apparatus, not only the fixing heater 52 but also a semiconductor laser (not shown) installed in the exposure apparatus 20 generates heat. For this reason, in order to suppress the temperature rise inside the image forming apparatus due to the heat generated by the semiconductor laser, a fan (not shown) as a cooling unit different from the cooling fan 60 installed in the vicinity of the fixing device 50 is provided in the exposure device 20. It is installed near. By driving this fan, the heat of the semiconductor laser is radiated to the outside of the image forming apparatus.

  The arithmetic processing unit 90 also includes an elapsed time from when the energization to the semiconductor laser is stopped until the next energization to the semiconductor laser and the energization to the semiconductor laser after the energization to the semiconductor laser is started. A counter (not shown) is installed as a second time measuring unit that measures the elapsed time until the stop. The measured value of the elapsed time from when the energization to the semiconductor laser measured by the counter is stopped until the next energization to the semiconductor laser is started and the energization to the semiconductor laser after the energization to the semiconductor laser is started. The measured value of the elapsed time until the energization is stopped is stored in the arithmetic processing unit.

Here, the minimum value t _min of the temperature inside the image forming apparatus is set, and the inside of the image forming apparatus is set according to the elapsed time from when the energization to the semiconductor laser is stopped until the energization to the semiconductor laser is stopped. Measure in advance how the temperature rises. In addition, the maximum value t _max of the temperature inside the image forming apparatus is set, and the current of the image forming apparatus is changed according to the elapsed time from when the energization to the semiconductor laser is stopped until the energization to the semiconductor laser is started next. Pre-measure how the internal temperature drops.

  Then, the elapsed time from when the energization to the semiconductor laser is started until the energization to the semiconductor laser is stopped and the elapsed time from when the energization to the semiconductor laser is stopped until the next energization to the semiconductor laser is started. A data table or mathematical expression representing the relationship between the time and the temperature inside the image forming apparatus is created and stored in the arithmetic processing unit 90.

  Further, the temperature inside the image forming apparatus is measured at the time of manufacturing the image forming apparatus, and the measured temperature inside the image forming apparatus is stored as an initial value in the arithmetic processing unit 90 at the time of manufacturing the image forming apparatus.

  As described above, the initial value of the temperature inside the image forming apparatus, the elapsed time from the start of energization to the semiconductor laser to the stop of energization of the semiconductor laser, and the energization of the semiconductor laser are stopped. Next, from the elapsed time until the energization of the semiconductor laser is started, the temperature inside the image forming apparatus when the recording paper is printed can be estimated.

  By configuring the image forming apparatus in this way, the measured value of the elapsed time from when the energization to the semiconductor laser by the counter is stopped until the next energization to the semiconductor laser and the energization to the semiconductor laser are performed. If the measured value of the elapsed time from the start of energization to the stop of energization of the semiconductor laser is input to the arithmetic processing unit 90, the temperature inside the image forming apparatus when continuous printing of the recording paper is started Can be calculated.

  In addition, the measured value of the elapsed time from when the power supply to the semiconductor laser is stopped by the counter to the next time the power supply to the semiconductor laser is started, and the power supply to the semiconductor laser is stopped after the power supply to the semiconductor laser is started Counter until reaching the timing for switching the rotational speed of the cooling fan 60 according to the temperature inside the image forming apparatus when the continuous printing of the recording paper calculated from the measured value of the elapsed time until the start is started The measurement value of the continuous print number of recording papers is set.

  During the operation of the image forming apparatus, in the exposure apparatus, not only the semiconductor laser but also the mirror motor for driving the polygon mirror described above generates heat. Therefore, the elapsed time from when the energization to the mirror motor is started until the energization to the mirror motor is stopped and the elapsed time from when the energization to the mirror motor is stopped until the energization to the mirror motor is started next. The time may be measured by a counter, and the internal temperature of the image forming apparatus when recording paper is printed may be calculated from the measured value of the counter.

As described above, in this embodiment, the rotation speed of the cooling fan 60 is switched according to the internal temperature of the image forming apparatus when continuous printing of recording paper is started. The present invention can also be applied to an ozone discharge fan (not shown) as a discharge product discharge fan for discharging ozone (O ₃ ) as a discharge product to the outside of the apparatus.

  Here, when a charging charger (not shown) is installed in the image forming apparatus in place of the above-described charging roller 11, the surface of the photosensitive drum is charged by corona discharge of the charging charger. During operation of the image forming apparatus, ozone is generated by corona discharge of the charging charger, and this ozone is released into the image forming apparatus. In addition, the amount of ozone generated increases as the number of continuous prints of recording paper increases, and the amount of ozone staying inside the image forming apparatus increases, thereby increasing the ozone concentration inside the image forming apparatus. Therefore, an ozone exhaust fan is installed inside the image forming apparatus in order to discharge ozone remaining inside the image forming apparatus to the outside of the image forming apparatus and keep the ozone concentration inside the image forming apparatus low. .

  Further, in this image forming apparatus, the elapsed time from when the energization to the charging charger is stopped until the next energization to the charging charger and the energization to the charging charger after the energization to the charging charger is started. A counter (not shown) serving as a third time measuring unit that measures the elapsed time until is stopped is installed in the arithmetic processing unit 90 shown in FIG. Then, the measured value of the elapsed time from when the electrification to the charging charger measured by the counter is stopped until the next electrification to the charging charger is started, and the electrification to the charging charger after the energization to the charging charger is started. The measured value of the elapsed time until the energization is stopped is stored in the arithmetic processing unit.

Here, the minimum value O _min of the ozone concentration inside the image forming apparatus is set, and according to the elapsed time from when the energization to the charging charger is started until the energization to the charging charger is stopped, Pre-measure how the internal ozone concentration rises. Further, the maximum ozone concentration O _max inside the image forming apparatus is set, and the image forming apparatus is set according to the elapsed time from when the energization to the charging charger is stopped until the energization to the charging charger is started next. It is measured in advance how the ozone concentration inside the water drops.

  Then, the elapsed time from the start of energization to the charging charger until the energization to the charging charger is stopped and the elapsed time from when the energization to the charging charger is stopped until the next energization to the charging charger is started. A data table or mathematical expression representing the relationship between time and the ozone concentration inside the image forming apparatus is created and stored in the arithmetic processing unit 90.

  Further, the ozone concentration inside the image forming apparatus is measured at the time of manufacturing the image forming apparatus, and the measured ozone concentration inside the image forming apparatus is stored as an initial value in the arithmetic processing unit 90 at the time of manufacturing the image forming apparatus. .

  As described above, the initial value of the ozone concentration inside the image forming apparatus, the elapsed time from when the energization to the charging charger is started until the energization to the charging charger is stopped, and the energization to the charging charger are stopped. The ozone concentration inside the image forming apparatus when the recording paper is printed can be estimated from the elapsed time until the energization of the charging charger is started next.

  By configuring the image forming apparatus in this way, the measured value of the elapsed time from when the energization to the charging charger by the counter is stopped until the next energization to the charging charger is started and the energization to the charging charger is performed. If the measured value of the elapsed time from when the charging is started to when the electrification to the charging charger is stopped is input to the arithmetic processing unit 90, the ozone inside the image forming apparatus when the continuous printing of the recording paper is started The concentration can be calculated.

  Also, the measured value of the elapsed time from when the energization to the charging charger is stopped by the counter until the next energization to the charging charger is started, and the energization to the charging charger is stopped after the energization to the charging charger is started. Until the timing to switch the rotation speed of the ozone discharge fan according to the ozone concentration inside the image forming apparatus when continuous printing of the recording paper calculated from the measured value of the elapsed time until the start is started The measurement value of the number of continuous prints of recording paper by the counter is set.

  In addition, the toner 31 is transferred to the printing surface of the recording paper by applying a positive charge to the surface opposite to the printing surface of the recording paper, not limited to the above-described charging charger, and printing of the recording paper. A transfer charger (not shown) that peels the recording paper from the surface of the photosensitive drum 3 by applying a negative charge to the surface opposite to the surface, or remains on the surface of the photosensitive drum 3 after the toner 31 is transferred to the recording paper. When a neutralization charger (not shown) that neutralizes the toner 31 and neutralizes the surface of the photosensitive drum 3 is installed, ozone is generated by corona discharge of the transfer charger and the neutralization charger.

  Therefore, when an ozone discharge fan that discharges ozone generated by corona discharge of the transfer charger to the outside of the image forming apparatus is installed inside the image forming apparatus, energization to the transfer charger is started and then the transfer charger is started. The counter is used to measure the elapsed time until the energization of the printer is stopped and the elapsed time from when the energization to the transfer charger is stopped until the next time the energization of the transfer charger is started. The ozone concentration inside the image forming apparatus when continuous printing is started may be calculated.

  Alternatively, when an ozone discharge fan that discharges ozone generated by corona discharge of the charge removal charger to the outside of the image forming apparatus is installed inside the image formation apparatus, energization to the charge removal charger is started after the start of energization to the charge removal charger. The elapsed time until the energization is stopped and the elapsed time from when the energization to the neutralization charger is stopped until the next time the energization to the neutralization charger is started are measured by the counter, and the recording paper is printed from the measured value of the counter. It is also possible to calculate the ozone concentration inside the image forming apparatus when.

In the above-described embodiment, during operation of the image forming apparatus, discharge products such as nitrogen oxide (NO _x ) are also generated by corona discharge of the charging charger, the transfer charger, or the discharging charger. . Therefore, the concentration of nitrogen oxide inside the image forming apparatus when continuous printing of recording paper is started and the concentration of nitrogen oxide inside the image forming apparatus when continuous printing of recording paper is started Accordingly, the timing for switching the rotational speed of the discharge product discharge fan for discharging the nitrogen oxide to the outside of the image forming apparatus may be changed.

<< Embodiment 3 of the Invention >>
In the third embodiment of the present invention, the configuration of the image forming apparatus of the first embodiment is changed. Here, the difference between the present embodiment and the first embodiment will be described.

  In the image forming apparatus of the present embodiment, a counter (not shown) as a date measuring unit that measures the date is installed in the arithmetic processing device 90 shown in FIG. Here, since the inside of the image forming apparatus is easily affected by heat external to the image forming apparatus, the temperature changes according to the season. As shown in FIG. 4, the relationship between the temperature of the fixing roller 51 and the internal temperature of the image forming apparatus when continuous printing of recording paper is started is represented by a one-dot chain line in the summer, and in the spring / autumn Is represented by a solid line and in winter by a broken line.

Further, as shown in FIG. 4, when the temperature of the fixing roller 51 detected by the temperature sensor 54 is t ₄ , the temperature inside the image forming apparatus when continuous printing of the recording paper is started is t _{7 in} summer. , low t ₆ than t ₇ in spring and autumn, to lower t ₅ than t ₆ in the winter, to change, respectively. That is, the temperature outside the image forming apparatus is the highest in summer, and decreases in the order of spring, autumn, and winter. Therefore, the temperature inside the image forming apparatus when recording paper is continuously printed is also in summer, spring, and autumn. It becomes lower in order of winter. On the other hand, the arithmetic processing device 90 according to the present embodiment has a function of correcting the temperature inside the image forming apparatus in accordance with each of the three modes of summer, spring / autumn, and winter. One of the two modes is selected.

Specifically, the arithmetic processing unit 90 calculates the internal temperature of the image forming apparatus when continuous printing of the recording paper is started from the temperature of the fixing roller 51, and one selected from the measured value of the counter. The temperature inside the image forming apparatus when continuous printing of recording paper is started is corrected according to the mode. That is, the arithmetic processing unit 90 uses the temperature inside the image forming apparatus when the continuous printing of the recording paper calculated from the temperature of the fixing roller 51 is started, for example, in the summer, based on spring and autumn. by adding -Δt if winter with added if + Delta] t long, t ₇ the temperature of the inside in summer of the image forming apparatus when the continuous printing of the recording sheet is started, spring and autumn in t _6, winter each corrected so that the t ₅ in.

  Further, as described in the first embodiment, the continuous printing of the recording paper by the counter until reaching the timing for switching the internal temperature of the image forming apparatus and the rotation speed of the cooling fan 60 when the continuous printing of the recording paper is started. By inputting the temperature inside the image forming apparatus when continuous printing of the recording paper corrected according to the season is started into a data table or a mathematical expression representing the relationship with the measured value of the number of sheets, the cooling fan 60 The measured value of the number of continuous prints of the recording paper by the counter until the timing for switching the rotation speed is reached is calculated.

  The arithmetic processing unit 90 is not limited to the three modes of summer, spring / autumn, and winter, but has four modes of spring, summer, autumn, and winter, and continuous printing of recording paper according to each mode. It may be configured to correct the temperature inside the image forming apparatus at the start of the operation. Alternatively, the arithmetic processing unit 90 is provided with twelve modes from January to December, and is configured to correct the internal temperature of the image forming apparatus when continuous printing of recording paper is started according to each mode. May be.

  In the image forming apparatus according to the second embodiment, a counter (not shown) serving as a date measuring unit that measures the above-described date is installed in the arithmetic processing unit 90, so that each mode selected from the measured value of the counter is set. Accordingly, the temperature inside the image forming apparatus when the continuous printing of the recording paper is started may be corrected.

  As described above, the present invention relates to an image forming apparatus, and is particularly useful for controlling the rotation speed of a cooling fan that dissipates heat generated inside the image forming apparatus to the outside of the image forming apparatus.

1 is a schematic diagram illustrating a structure of an image forming apparatus according to the present invention. FIG. 6 is a block diagram illustrating an operation of the image forming apparatus according to the present invention. 3 is a diagram illustrating a relationship between the number of continuous prints of recording paper and the temperature inside the image forming apparatus in the single-sided printing mode and the double-sided printing mode in the image forming apparatus according to Embodiment 1. FIG. In the image forming apparatus according to the third embodiment, the relationship between the temperature of the fixing roller for each season and the temperature inside the image forming apparatus when continuous printing of recording paper is started is illustrated.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Main-body part 2 Reversing part 3 Photosensitive drum 10 Charging apparatus 11 Charging roller 20 Exposure apparatus 30 Developing apparatus 31 Toner 32 Developing roller 40 Transfer apparatus 41 Transfer roller 50 Fixing apparatus 51 Fixing roller 52 Fixing heater 53 Pressure roller 54 Temperature sensor 60 Cooling Fan 70 Paper feed cassette 71 Paper feed rollers 72, 78 Transport roller 73 Registration roller 74 Transport guide 75 Discharge direction switching guide 76 Paper discharge roller 77 Paper discharge tray 79 Transport unit 80 Reverse roller 81 Lower tray 82 Upper tray 90 Arithmetic processor 91 Power supply device 92 Control device

Claims (10)

A fixing unit having a fixing roller and a heater for heating the fixing roller; and a fixing unit configured to fix the toner on the recording paper passing through the fixing roller heated by the heater; and at least heat of the fixing unit is radiated to the outside of the apparatus And an image forming apparatus including a cooling unit that cools the inside of the apparatus,
The elapsed time from when the energization to the heater is stopped before the continuous printing of the recording paper is started to the next time the energization of the heater is started, and the time before the continuous printing of the recording paper is started A first time measuring unit that measures an elapsed time from when the energization to the heater is started to when the energization to the heater is stopped;
While the continuous printing of the recording paper is performed, the cooling capacity of the cooling unit is adjusted, and the continuous printing of the recording paper is started from the first measurement value of the first time measurement unit. An image forming apparatus that calculates a temperature and changes a timing for adjusting a cooling capacity of the cooling unit according to a temperature inside the apparatus. A fixing unit having a fixing roller and a heater for heating the fixing roller; and a fixing unit configured to fix the toner on the recording paper passing through the fixing roller heated by the heater; and at least heat of the fixing unit is radiated to the outside of the apparatus And an image forming apparatus including a cooling unit that cools the inside of the apparatus,
An exposure unit that includes a light emitting unit and emits laser light from the light emitting unit toward the photosensitive drum;
The elapsed time from when the power supply to the light emitting unit is stopped before the continuous printing of the recording paper is started to the next time the power supply to the light emitting unit is started, and before the continuous printing of the recording paper is started A second time measuring unit for measuring an elapsed time from when energization to the light emitting unit is started to when energization to the light emitting unit is stopped;
With
The cooling unit cools the inside of the apparatus by radiating the heat of the exposure unit to the outside of the apparatus,
While the continuous printing of the recording paper is performed, the cooling capacity of the cooling unit is adjusted, and the continuous printing of the recording paper is started from the second measurement value of the second time measurement unit. An image forming apparatus that calculates a temperature and changes a timing for adjusting a cooling capacity of the cooling unit according to a temperature inside the apparatus. A fixing unit having a fixing roller and a heater for heating the fixing roller; and a fixing unit configured to fix the toner on the recording paper passing through the fixing roller heated by the heater; and at least heat of the fixing unit is radiated to the outside of the apparatus And an image forming apparatus including a cooling unit that cools the inside of the apparatus,
A temperature sensor for detecting the temperature of the fixing roller, and a counter for counting the date,
While the continuous printing of the recording paper is being performed, the cooling capacity of the cooling unit is adjusted, and the continuous printing of the recording paper is started from the temperature information of the temperature sensor when the continuous printing of the recording paper is started. The temperature inside the apparatus is calculated, the temperature inside the apparatus when continuous printing of recording paper is started is corrected according to the count of the counter, and the cooling is performed according to the corrected temperature inside the apparatus An image forming apparatus comprising: changing the timing for adjusting the cooling capacity of a part. An exposure unit that includes a light emitting unit and emits laser light from the light emitting unit toward the photosensitive drum;
The image forming apparatus according to claim 1, wherein the cooling unit cools the inside of the apparatus by radiating heat of the exposure unit to the outside of the apparatus. With a counter that counts the date,
Correct the temperature inside the apparatus when continuous printing of recording paper is started according to the count of the counter,
The image forming apparatus according to claim 1, wherein the timing for adjusting the cooling capacity of the cooling unit is changed in accordance with the corrected temperature inside the apparatus. The cooling unit is a cooling fan, and when the number of continuous prints of recording paper after starting printing reaches a predetermined value, the cooling speed of the cooling unit is adjusted by switching the rotation speed of the cooling fan, and The image forming apparatus according to claim 1, wherein the timing for adjusting the cooling capacity of the cooling unit is set according to the number of continuous prints of the recording paper. The cooling unit is a cooling fan, and when the continuous printing time of the recording paper after starting printing reaches a predetermined value, the rotation speed of the cooling fan is switched to adjust the cooling capacity of the cooling unit, and The image forming apparatus according to claim 1, wherein the timing for adjusting the cooling capacity of the cooling unit is set according to a continuous printing time of the recording paper. A charger that generates electric charge for applying an electric action to the photosensitive drum;
A discharge product discharge fan for discharging the discharge product generated by the discharge of the charger to the outside of the apparatus;
The elapsed time from when the energization to the charger is stopped before the continuous printing of the recording paper is started to the next time the energization of the charger is started, and the time before the continuous printing of the recording paper is started A third time measuring unit for measuring an elapsed time from when the energization to the charger is started to when the energization to the charger is stopped;
With
When the rotation speed of the discharge product discharge fan is switched while continuous printing of recording paper is being performed, and continuous printing of recording paper is started from the third measurement value of the third time measurement unit The concentration of the discharge product inside the apparatus is calculated, and the timing for switching the rotational speed of the discharge product discharge fan is changed according to the concentration of the discharge product. The image forming apparatus according to any one of the above. When the number of continuous prints of recording paper after starting printing reaches a predetermined value, the rotation speed of the discharge product discharge fan is switched and the timing of switching the rotation speed of the discharge product discharge fan is changed to the recording paper. The image forming apparatus according to claim 8, wherein the image forming apparatus is set according to the number of continuous prints. When the continuous printing time of the recording paper from the start of printing reaches a predetermined value, the rotation speed of the discharge product discharge fan is switched and the timing of switching the rotation speed of the discharge product discharge fan is changed to the recording paper. The image forming apparatus according to claim 8, wherein the image forming apparatus sets the continuous printing time.

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