JP2010002601A - Image forming apparatus, control method and control program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve power saving and quiet sound of a fan motor by rotating the fan motor at appropriate rotational speed in accordance with a state inside a machine. <P>SOLUTION: The image forming apparatus includes at least a PWM fan motor for controlling the rotational speed in a duty ratio of a pulse in a PWM system, and a temperature/humidity detection means detecting temperature and/or humidity. The apparatus includes a control part which compares the temperature and/or humidity detected by the temperature/humidity detection means with target temperature and/or humidity equal to or under allowable temperature and/or allowable humidity, and performs control to decrease the rotational speed of the PWM fan motor by making the duty ratio small when the detected temperature and/or humidity is lower than the target temperature and/or humidity. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus, a control method, and a control program, and in particular, an image forming apparatus equipped with a fan motor capable of varying a rotation speed by a pulse duty ratio in a pulse width modulation (PWM) system, and the fan The present invention relates to a control method and a control program for controlling the rotational speed of a motor.

  In an electrophotographic image forming apparatus, a photosensitive drum uniformly charged by a charging device is irradiated with light from an exposure device to form an electrostatic latent image, and toner is attached to the electrostatic latent image by a developing device. The toner image is visualized as a toner image, the toner image is transferred from the photosensitive drum to a paper medium via an intermediate transfer belt, and then the toner image is fixed on the paper medium by heating and pressing with a fixing device. It is carried out.

  In such an image forming apparatus, heat is generated from the fixing device, electrical parts, etc., and the image quality deteriorates when the internal temperature rises due to the generated heat. Therefore, the fan motor is rotated to exhaust the heat accumulated in the apparatus. ing. Further, since ozone is generated from the charging device and the transfer device and the generated ozone is accumulated in the apparatus, the image quality is deteriorated. Therefore, the fan motor is rotated to exhaust the accumulated ozone in the apparatus. Further, the transfer device handles charged toner, and the image quality deteriorates when the humidity in the machine rises. Therefore, the fan motor is rotated to exhaust the moisture accumulated in the machine.

  Regarding the control of the fan motor, for example, Patent Document 1 listed below discloses a blower that discharges ozone air around the image forming process to the outside, a function of controlling the amount of blown air, an ozone filter that absorbs ozone, An image forming apparatus is disclosed that includes an ozone sensor that detects a density, and that has a function of reducing the amount of air blown when a detection signal from the ozone sensor falls below a predetermined density.

Japanese Patent No. 3108589

  The fan motor may be rotated at a high speed in order to effectively discharge the heat, moisture, ozone, etc. accumulated in the machine. However, if the fan motor is rotated at a high speed, the noise generated by the fan motor or the fan motor The power consumption increases. Therefore, the fan motor is preferably rotated at an appropriate rotation speed according to the state in the machine.

  However, current fan motors perform speed control by inserting a deceleration resistor, and can be adjusted only in two stages due to cost constraints. Therefore, assuming the worst print mode in which the temperature rises the most, the rotation speed of the fan motor must be determined. In the print mode in which the temperature does not rise so much, the fan motor is rotated at a higher speed than necessary. Thus, there has been a problem that noise and power consumption of the fan motor become excessive.

  The present invention has been made in view of the above problems, and its main purpose is to reduce the power consumption and the noise of the fan motor by rotating the fan motor at an appropriate rotational speed in accordance with the state in the machine. It is an object to provide an image forming apparatus, a control method, and a control program.

  In order to achieve the above object, the present invention provides at least an image forming apparatus including a PWM fan motor capable of controlling a rotation speed with a duty ratio of a pulse in a PWM system, and a temperature / humidity detecting means for detecting temperature and / or humidity. In the apparatus, the temperature and / or humidity detected by the temperature / humidity detecting means is compared with a target temperature and / or humidity that is equal to or lower than the allowable temperature and / or allowable humidity, and the detected temperature and / or humidity is When the temperature and / or humidity is lower than the target, the control unit includes a control unit that performs control to decrease the duty ratio and reduce the rotation speed of the PWM fan motor, and the control unit detects the detected When the temperature and / or humidity is higher than the target temperature and / or humidity, the duty ratio is increased to increase the PWM fan motor. Even if the rotational speed is increased and the duty ratio is maximized, if the detected temperature and / or humidity does not reach the target temperature and / or humidity, a control is performed to notify the occurrence of a trouble. can do.

  According to another aspect of the present invention, there is provided an image forming apparatus including at least a PWM fan motor capable of controlling a rotation speed with a duty ratio of a pulse in a PWM method, and a sound detection unit that detects sound, and noise detected by the sound detection unit. When the detected noise level is lower than the target noise level, the duty ratio is increased and the rotational speed of the PWM fan motor is compared. A control unit that performs control to increase the rotational speed of the PWM fan motor when the detected noise level is higher than the target noise level and the duty ratio is decreased. Even if the speed is reduced and the duty ratio is minimized, the detected noise level will not reach the target noise level. If There may be configured to perform control to notify the occurrence of trouble.

  The present invention also relates to a method for controlling a PWM fan motor in an image forming apparatus equipped with a PWM fan motor capable of controlling the rotation speed with a pulse duty ratio in the PWM method, wherein the temperature and / or humidity in the apparatus is controlled. A detecting step for detecting, a comparing step for comparing the detected temperature and / or humidity with a target temperature and / or humidity below the allowable temperature and / or allowable humidity, and the detected temperature and / or humidity When the temperature and / or humidity is lower than the target temperature, at least the control step of decreasing the duty ratio and decreasing the rotational speed of the PWM fan motor is executed. In the control step, the detection is performed. If the measured temperature and / or humidity is higher than the target temperature and / or humidity, the duty ratio is increased. If the detected temperature and / or humidity does not reach the target temperature and / or humidity even when the rotational speed of the PWM fan motor is increased and the duty ratio is maximized, trouble may occur. It can be set as the structure to notify.

  The present invention is also a method for controlling a PWM fan motor in an image forming apparatus equipped with a PWM fan motor capable of controlling the rotation speed with a pulse duty ratio in the PWM method, and detecting the noise level in the apparatus. A comparison step comparing the detected noise level with a target noise level equal to or lower than an allowable noise level; and if the detected noise level is lower than the target noise level, the duty ratio is increased. And at least a control step for increasing the rotational speed of the PWM fan motor. In the control step, if the detected noise level is higher than the target noise level, the duty ratio is To reduce the rotational speed of the PWM fan motor and the duty ratio Even with minimal, if the detected noise level is not the noise level to the target may be configured to notify the occurrence of trouble.

  Further, the present invention provides a control that operates in an image forming apparatus that includes at least a PWM fan motor capable of controlling the rotation speed with a pulse duty ratio in the PWM system, and a temperature / humidity detection unit that detects temperature and / or humidity. A program that compares a temperature and / or humidity detected by the temperature / humidity detection means with a target temperature and / or humidity that is equal to or lower than an allowable temperature and / or allowable humidity, and detects the detected temperature and / or humidity When the humidity is lower than the target temperature and / or humidity, the duty ratio is decreased to function as a control unit that performs control to reduce the rotational speed of the PWM fan motor.

  According to another aspect of the present invention, there is provided a control program that operates on an image forming apparatus including at least a PWM fan motor capable of controlling a rotation speed with a pulse duty ratio in a PWM system, and a sound detection unit that detects sound, Comparing the noise level detected by the sound detection means with a target noise level equal to or lower than an allowable noise level, and if the detected noise level is lower than the target noise level, increase the duty ratio. Thus, it functions as a control unit that performs control to increase the rotational speed of the PWM fan motor.

  According to the image forming apparatus, the control method, and the control program of the present invention, the following effects can be obtained.

  The first effect of the present invention is that the rotational speed of the fan motor can be optimized for all print modes, and the power consumption and noise reduction of the fan motor can be achieved.

  The reason for this is that a PWM fan motor that can arbitrarily control its rotational speed by changing the pulse duty in the PWM system is used as the fan motor, and the target is based on in-machine temperature information, humidity information, and noise information. This is because the duty ratio is set so that the temperature, humidity and noise of the PWM fan motor are controlled, and the rotational speed of the PWM fan motor is controlled.

  The second effect of the present invention is that the image forming apparatus can be appropriately operated.

  The reason is that even if the rotational speed of the PWM fan motor is changed, if the target temperature, humidity, and noise do not occur, it is determined that a failure has occurred, a trouble code is issued, and control is performed to notify the user of the occurrence of the trouble. It is.

  As shown in the background art, in the image forming apparatus, heat, moisture, ozone, and the like accumulated in the apparatus are exhausted by rotating a fan motor. As the speed control of this fan motor, conventionally, a method of changing the rotational speed by inserting a deceleration resistor has been used, so the rotational speed cannot be finely controlled according to the state in the machine, and it is faster than necessary. Rotating the fan motor has a problem of increasing power consumption and noise.

  On the other hand, a motor that performs speed control by the PWM method is known, and in this type of motor, the pulse duty ratio (ratio of one cycle to a high pulse side width, hereinafter referred to as PWMDUTY) is changed. The rotation speed can be arbitrarily controlled.

  Therefore, in the present invention, a motor (hereinafter referred to as a PWM fan motor) that performs speed control by the PWM method is used as a fan motor for exhausting heat, moisture, ozone, and the like accumulated in the machine. Based on sound information such as temperature information, humidity information, and fan rotation sound, PWMDUTY is set so as to achieve the target temperature, humidity, and noise, and control is performed to change the rotation speed of the PWM fan motor. If the PWM DUTY cannot be set so that the target temperature, humidity, and noise can be achieved, it is determined that there is a component failure and control is performed to generate a service call.

  Although the motor itself that performs speed control by the PWM method is known, the idea of using the PWM fan motor as the fan motor of the image forming apparatus and controlling the rotational speed of the PWM fan motor according to the state in the machine is as follows: This is a new idea based on the knowledge of the present inventor.

  In order to describe the above-described embodiment of the present invention in more detail, an image forming apparatus, a control method, and a control program according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional view schematically showing the structure of the image forming apparatus of the present embodiment, and FIG. 2 is a diagram schematically showing the control configuration of the fan motor of the present embodiment. FIG. 3 is a diagram showing the relationship between PWMDUTY and the rotational speed of the PWM fan motor, and FIGS. 4 to 7 are diagrams showing examples of speed control of the PWM fan motor of the present embodiment, FIGS. 9 is a flowchart showing a specific speed control procedure of the PWM fan motor of the present embodiment.

  First, the structure of the image forming apparatus of this embodiment will be described. FIG. 1 shows a cross-sectional structure of the main part of a tandem color printer, and suffixes (Y, M, C, K) in the figure indicate yellow, magenta, cyan, and black, respectively. . Hereinafter, an image forming unit and a conveyance unit which are main components of the image forming apparatus will be outlined.

  The image forming unit includes image forming units 20Y, 20M, 20C, and 20K each including a photosensitive member, a charging unit that charges the photosensitive member, an exposure unit that exposes an image pattern, and a developing unit that develops toner, The intermediate transfer belt 31 that forms an image by superimposing the four color toner images formed thereon, rollers 32 to 34 that drive the intermediate transfer belt 31, and the like.

  The transport unit includes a paper feed roller 42 that feeds the recording medium from the automatic paper feed cassette 41, a transport roller 43 that transports the fed recording medium, and a toner image formed on the intermediate transfer belt 31. The image forming apparatus includes a secondary transfer roller 35 that transfers the toner image onto the recording medium, a fixing unit 36 that fixes the toner image transferred onto the recording medium, and a discharge roller 37 that discharges the conveyed recording medium or conveys it to the double-sided conveyance path. ing.

  In the image forming apparatus having the above-described configuration, heat or the like is easily generated in each unit (particularly the image forming unit), and thus one or a plurality of fans 100 are arranged at predetermined positions in the apparatus. Further, since it is necessary to acquire temperature information, humidity information, and sound information in order to control the rotation speed of the fan 100, temperature detection means, humidity detection means, sound detection means, etc. are arranged at predetermined positions in the machine. Has been. Furthermore, a control unit (not shown) for controlling the operation of each unit of the image forming apparatus is provided at a predetermined position in the apparatus.

  Here, in the image forming apparatus having the above-described configuration, the number of rotations per unit time of the fan (hereinafter simply referred to as the number of rotations) is a print mode in which the temperature rise is highest due to the evaluation performed in advance. The rotation speed is set so as to satisfy the temperature standard values of all parts. However, with such a setting, in the print mode in which the temperature does not rise so much, the number of revolutions becomes excessive, and extra power is consumed, and the rotation sound of the fan also increases.

  Therefore, in this embodiment, a PWM fan motor is used as the fan 100, and the rotational speed is controlled by PWMDUTY, so that the fan can be rotated at an appropriate rotational speed for all print modes without increasing the cost of the conventional fan. 100 is rotated.

  FIG. 2 shows a control configuration of the PWM fan. A control unit (CPU: Central Processing Unit) generates a PWM signal and sends it to the PWM fan motor. At that time, temperature information, humidity information, and sound information are acquired from the temperature detecting means, humidity detecting means, sound detecting means, etc., and the PWM DUTY is increased / decreased based on these information so as to obtain a desired temperature, humidity, and noise. To adjust the rotation speed.

  In addition, the PWM fan motor emits a pulse signal (rotation number signal) indicating how many rotations it is currently rotating. By inputting this pulse signal to a control unit (for example, a timer port of a CPU), The control unit can recognize the rotational speed of the fan.

  The control of the PWM fan motor may be executed by hardware, or may be executed by a control program that causes a computer to function as the control unit.

  Next, a method for controlling the PWM fan motor will be described with a specific example.

  FIG. 3 is a characteristic diagram of the PWM fan motor used in the image forming apparatus of the present embodiment, and shows the relationship between PWMDUTY (H logic) and fan rotation speed (rpm). As shown in FIG. 3, the longer the time of PWMDUTY (H logic) of the PWM signal, the higher the fan speed increases. By changing the PWMDUTY (H logic) time, the fan speed can be controlled. It becomes possible.

  FIG. 4 shows the time and temperature detection from the start of rotation when the PWM fan motor is operated at 3500 rpm in print mode A for single-sided printing and when the PWM fan motor is operated at 3500 rpm in print mode B for double-sided printing. The relationship between the temperature detected by the means and the temperature is illustrated. The print mode A is a mode in which the temperature rise is the highest, and the print mode B is a mode having a margin for the allowable temperature.

  In this case, since there is a margin with respect to the allowable temperature in the print mode B, for example, as shown in FIG. 5, even if the rotational speed of the PWM fan is decreased from 3500 rpm to 2500 rpm, the temperature rise curve is the same as the print mode A. The allowable temperature is not exceeded. Therefore, when the temperature detected by the temperature detection means is lower than the allowable temperature of the device, the control unit (control program) decreases the PWM DUTY (H logic) within a range that is equal to or lower than the allowable temperature of the device, and the PWM fan motor. Control to reduce the rotation speed. Thereby, it is possible to achieve power saving and noise reduction of the PWM fan motor.

  Here, the print mode A for single-sided printing and the print mode B for double-sided printing are illustrated here, but the control performed by the control unit (control program) can be applied to any print mode, and a predetermined print mode. The present invention can also be applied to a sequence in which the inside temperature increases.

  FIG. 6 is a diagram illustrating noise levels generated by the fans when the image forming apparatus includes the fans A and B, and the fans A and B are operated at 3500 rpm. This indicates that the fan rotation noise varies.

  In this case, since the fan A exceeds the allowable noise, it is necessary to reduce the rotational speed. For example, as shown in FIG. 7, if the rotational speed of the fan A is reduced from 3500 rpm to 3000 rpm, the noise equivalent to the fan B is obtained. It becomes a level and becomes less than allowable noise. Therefore, when the sound detected by the sound detection means exceeds the allowable noise of the device, the control unit (control program) decreases the PWM DUTY (H logic) so that the noise is less than the allowable noise of the device, and the PWM fan. Control to reduce the motor speed.

  Here, although the rotational speed of the PWM fan motor is reduced based on the sound information, there is a possibility that the cooling capacity of the PWM fan motor may be reduced by reducing the rotational speed of the PWM fan motor. In that case, the rotational speed of the PWM fan motor can be lowered within a range where the temperature in the machine is equal to or lower than the allowable temperature.

  As described above, the value detected by each detection unit of the image forming apparatus is compared with a preset allowable value, and the rotational speed of the PWM fan motor is reduced within a range that is equal to or smaller than the allowable value, thereby saving power. Silence can be achieved.

  Hereinafter, a specific control procedure of the PWM fan motor will be described with reference to the flowcharts of FIGS.

[When controlling based on temperature and humidity]
First, in step S101 in the flowchart of FIG. 8, simultaneously with the start of printing, a PWM signal is sent from the CPU to the PWM fan motor. In step S102, the PWM fan motor is rotated based on the PWM signal.

  Next, the temperature / humidity detection means in the machine detects the temperature / humidity, and the control unit (control program) detects the detected temperature / humidity and the target temperature / humidity in steps S103 and S104 (for example, as described above). Compared to a value below the allowable temperature and close to the allowable temperature). The structure of the temperature and humidity detection means is not particularly limited. For example, as the temperature detection means, a platinum resistance thermometer or thermistor, a thermocouple, a sensor using the temperature characteristics of the transistor, a sensor using thermal expansion, A thermal infrared sensor, a quantum infrared sensor, or the like can be used. As the humidity detection means, a polymer sensor, a metal oxide sensor, an electrolyte sensor, or the like that detects a change in impedance or capacitance can be used. .

  If the detected temperature and humidity are lower than the target temperature and humidity (Yes in step S103 and No in step S104), the temperature and humidity in the machine can be increased, so control is performed in step S105. The unit (control program) decreases the PWM DUTY (H logic) of the PWM signal to lower the rotational speed of the PWM fan motor, and then returns to step S103.

  On the other hand, if the detected temperature and humidity are higher than the target temperature and humidity (No in step S103), the temperature and humidity inside the machine must be lowered. ) Increases the PWM duty (H logic) of the PWM signal to increase the rotational speed of the PWM fan motor.

  Thereafter, in step S107, the control unit (control program) determines whether PWMDUTY (H logic) is 100%, and if not 100%, returns to step S103. On the other hand, if it is 100%, even if the number of rotations of the PWM fan motor is increased, the target temperature and humidity cannot be achieved, and there is a risk of component failure, so a trouble code is generated.

  Then, during the printing operation, the above operation is repeated until the difference between the detected temperature and humidity and the target temperature and humidity becomes 0 (Yes in Step S103 and Yes in Step S104).

  In this way, the actual temperature and humidity are compared with the target temperature and humidity. If the actual temperature and humidity are lower than the target temperature and humidity, the PWM DUTY (H logic) of the PWM signal is reduced to reduce the PWM fan. By performing the control to reduce the rotational speed of the motor, the noise and power consumption of the PWM fan motor can be suppressed. Further, when the actual temperature and humidity are higher than the target temperature and humidity and the PWMDUTY (H logic) is the maximum (100%), control for generating a trouble code is performed to perform image formation. The device can be operated properly.

[When controlling based on sound]
First, in step S201 in the flowchart of FIG. 9, a PWM signal is sent from the CPU to the PWM fan motor simultaneously with the start of printing. In step S202, the PWM fan motor is rotated based on the PWM signal.

  Next, the sound detection means in the aircraft detects the sound in the aircraft, and the control unit (control program) detects the detected sound and the target sound (for example, the allowable noise below the allowable noise described above in steps S203 and S204). (Value close to). The structure of the sound detection means is not particularly limited, and for example, an electrodynamic, electrostatic, or piezoelectric microphone can be used.

  If the detected sound is lower than the target sound (Yes in step S203 and No in step S204), it is better to increase the cooling capacity even if the in-flight noise level increases, so in step S205 After increasing the PWM duty (H logic) of the PWM signal to increase the rotational speed of the PWM fan motor, the process returns to step S203.

  On the other hand, if the detected sound is higher than the target sound (in the case of No in step S203), it is necessary to lower the in-flight noise level. In step S206, the control unit (control program) PWMDUTY (H logic) is decreased to decrease the rotational speed of the PWM fan motor.

  Thereafter, in step S207, the control unit (control program) determines whether PWMDUTY (H logic) is 0%, and if not 0%, returns to step S203. On the other hand, if it is 0%, the target sound cannot be obtained even if the rotational speed of the PWM fan motor is lowered, and there is a risk of component failure, so a trouble code is generated.

  Then, during the printing operation, the above operation is repeated until the difference between the detected sound and the target sound becomes zero (Yes in Step S203 and Yes in Step S204).

  As described above, the actual sound is compared with the target sound, and if the actual sound is higher than the target sound, the PWM duty (H logic) of the PWM signal is reduced to reduce the rotational speed of the PWM fan motor. By performing the above, noise and power consumption of the PWM fan can be suppressed. Further, when PWMDUTY (H logic) is minimum (0%), it is possible to appropriately operate the image forming apparatus by performing control to generate a trouble code.

  In FIG. 8, the rotational speed of the PWM fan motor is controlled based on temperature and humidity, and in FIG. 9, the rotational speed of the PWM fan motor is controlled based on sound. The temperature, humidity, and sound may be controlled to be within acceptable ranges.

  In the above flow, the rotation speed of the PWM fan is controlled based on temperature, humidity, and sound. However, the control is similarly performed for arbitrary information (for example, ozone amount) that affects the operation of the image forming apparatus. can do.

  In the above embodiment, the control of the present invention is applied to the PWM fan motor mounted on the image forming apparatus. However, the present invention is not limited to the above embodiment, and is mounted on an arbitrary apparatus. The same can be applied to the PWM motor.

  The present invention can be used for an image forming apparatus equipped with a PWM fan motor capable of changing the number of rotations according to a pulse duty ratio in the PWM system, a PWM fan motor control method in the image forming apparatus, and a control program.

1 is a cross-sectional view illustrating a main structure of an image forming apparatus (tandem color printer) according to an embodiment of the present invention. FIG. 3 is a diagram schematically illustrating a control configuration of a fan motor of an image forming apparatus according to an embodiment of the present invention. It is a figure which shows the relationship between PWMDUTY and the rotation speed in the PWM fan motor which concerns on one Example of this invention. It is a figure which shows the temperature characteristic in print mode A and print mode B. 6 is a diagram illustrating a fan motor control example for a print mode B. FIG. It is a figure which shows the noise characteristic of the fan A and the fan B. 4 is a diagram illustrating an example of control for a fan A. FIG. It is a flowchart figure which shows the control procedure (when controlling based on temperature and humidity) of the fan motor which concerns on one Example of this invention. It is a flowchart figure which shows the control procedure (when controlling based on a sound) of the fan motor which concerns on one Example of this invention.

Explanation of symbols

2 automatic document feeder 3 paper feed tray 4 platen cover 10 image reader unit 11 platen glass 20 transport unit 20Y, 20M, 20C, 20K image forming unit 25Y, 25M, 25C, 25K transfer charger 30 image forming unit 31 intermediate transfer belt 32 , 33, 34 Roller 35 Secondary transfer roller 36 Fixing part 37 Paper discharge roller 38 Paper discharge tray 40 Paper feed part 41 Automatic paper feed cassette 42 Paper feed roller 43 Transport roller 100 Fan

Claims (12)

In an image forming apparatus comprising at least a PWM fan motor capable of controlling a rotation speed by a duty ratio of a pulse in a PWM method, and a temperature / humidity detection unit for detecting temperature and / or humidity,
The temperature and / or humidity detected by the temperature / humidity detection means is compared with a target temperature and / or humidity that is lower than or equal to the allowable temperature and / or allowable humidity, and the detected temperature and / or humidity is the target. An image forming apparatus comprising: a control unit that performs control to reduce the rotational speed of the PWM fan motor by reducing the duty ratio when the temperature and / or humidity is lower.   When the detected temperature and / or humidity is higher than the target temperature and / or humidity, the control unit increases the duty ratio to increase the rotational speed of the PWM fan motor, and 2. The control according to claim 1, wherein even if the duty ratio is maximized, if the detected temperature and / or humidity does not reach the target temperature and / or humidity, control is performed to notify the occurrence of a trouble. Image forming apparatus. In an image forming apparatus comprising at least a PWM fan motor capable of controlling a rotation speed with a duty ratio of a pulse in a PWM method, and a sound detection means for detecting sound,
The noise level detected by the sound detection means is compared with a target noise level equal to or lower than an allowable noise level. If the detected noise level is lower than the target noise level, the duty ratio is increased. An image forming apparatus comprising a control unit that performs control to increase the rotational speed of the PWM fan motor.   When the detected noise level is higher than the target noise level, the control unit decreases the duty ratio, decreases the rotational speed of the PWM fan motor, and minimizes the duty ratio. 4. The image forming apparatus according to claim 3, wherein when the detected noise level does not reach the target noise level, control is performed to notify the occurrence of a trouble. A method for controlling the PWM fan motor in an image forming apparatus equipped with a PWM fan motor capable of controlling the rotation speed with a duty ratio of a pulse in the PWM method,
A detection step for detecting temperature and / or humidity in the device;
A comparison step of comparing the detected temperature and / or humidity with a target temperature and / or humidity below the allowable temperature and / or allowable humidity;
When the detected temperature and / or humidity is lower than the target temperature and / or humidity, at least the control step of decreasing the duty ratio and decreasing the rotational speed of the PWM fan motor is executed. A control method characterized by the above.   In the control step, if the detected temperature and / or humidity is higher than the target temperature and / or humidity, the duty ratio is increased to increase the rotational speed of the PWM fan motor, and 6. The control method according to claim 5, wherein even when the duty ratio is maximized, if the detected temperature and / or humidity does not reach the target temperature and / or humidity, the occurrence of a trouble is notified. . A method for controlling the PWM fan motor in an image forming apparatus equipped with a PWM fan motor capable of controlling the rotation speed with a duty ratio of a pulse in the PWM method,
A detection step for detecting a noise level in the device;
A comparison step for comparing the detected noise level with a target noise level equal to or lower than an allowable noise level;
When the detected noise level is lower than the target noise level, at least the control step of increasing the duty ratio and increasing the rotational speed of the PWM fan motor is executed. .   In the control step, when the detected noise level is higher than the target noise level, the duty ratio is decreased, the rotational speed of the PWM fan motor is decreased, and the duty ratio is minimized. However, when the detected noise level does not reach the target noise level, the occurrence of a trouble is notified. A control program that operates in an image forming apparatus including at least a PWM fan motor capable of controlling a rotation speed with a pulse duty ratio in a PWM method, and a temperature / humidity detection unit that detects temperature and / or humidity,
Computer
The temperature and / or humidity detected by the temperature / humidity detection means is compared with a target temperature and / or humidity that is lower than or equal to the allowable temperature and / or allowable humidity, and the detected temperature and / or humidity is the target. When the temperature and / or humidity is lower, the control program is made to function as a control unit that performs control to reduce the rotational speed of the PWM fan motor by reducing the duty ratio.   When the detected temperature and / or humidity is higher than the target temperature and / or humidity, the control unit increases the duty ratio to increase the rotational speed of the PWM fan motor, and 10. The control according to claim 9, wherein even when the duty ratio is maximized, if the detected temperature and / or humidity does not reach the target temperature and / or humidity, control is performed to notify the occurrence of a trouble. Control program. A control program that operates in an image forming apparatus including at least a PWM fan motor capable of controlling a rotation speed with a duty ratio of a pulse in a PWM method, and a sound detection unit that detects sound,
Computer
The noise level detected by the sound detection means is compared with a target noise level equal to or lower than an allowable noise level. If the detected noise level is lower than the target noise level, the duty ratio is increased. A control program that functions as a control unit that performs control to increase the rotational speed of the PWM fan motor.   When the detected noise level is higher than the target noise level, the control unit decreases the duty ratio, decreases the rotational speed of the PWM fan motor, and minimizes the duty ratio. The control program according to claim 11, wherein when the detected noise level does not reach the target noise level, control for notifying occurrence of a trouble is performed.

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