JP2005178166A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device capable of forming images without lowering the durability and reliability of a rotary polygonal mirror and a motor to drive the mirror. <P>SOLUTION: The image forming device has an image writer 42 having the rotary polygonal mirror 42c makes a laser beam scan an image carrier 1, a motor 42f to drive the rotary polygonal mirror 42c, and a cooling fan 42g to cool the motor 42f, a fan driving current detection means 81 to detect the driving current of the cooking fan 42g, a normal value storage means 82 to store the value of the driving current when the cooling fan 42g is normal, a comparison/computation means 83 to compute a ratio by comparing the driving current value sensed by the fan driving current detection means 81 with the driving current value stored in the normal value storage means 82. The comparison/computation means 83 sets the revolution of the motor 42f in accordance with the ratio computed and forms an image at an image forming speed corresponding to the revolution. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus having a cooling fan that cools a motor that drives a rotary polygon mirror, and the number of rotations of the motor can be controlled in accordance with the drive current value of the cooling fan.

  As an image writing apparatus in an image forming apparatus such as a laser printer, a laser scanning type is known. This is composed of a laser light source, a rotating polygon mirror (polygon mirror), a motor (polygon motor) for driving the rotating polygon mirror, a scanning lens, and the like, and the light emitted from the laser light source is rotated at a constant angular velocity by the motor. It is deflected by the rotating polygon mirror to form an electrostatic latent image on the surface of the image carrier.

  As the speed of the image forming apparatus increases, the rotational speed of the motor that drives the rotary polygon mirror also increases, and depending on the model of the image forming apparatus, there may be a speed of 50,000 rpm. When the rotational speed of the motor increases, heat generation due to windage loss of the rotary polygon mirror and friction loss due to friction between the bearing surface and air increases, and the temperature of the rotary polygon mirror and the motor increases. This rise in temperature causes expansion of the rotating polygon mirror, expansion of the rotating shaft connecting the motor and the rotating polygon mirror, and the like, and hinders image formation. In order to prevent this, the outside air is generally taken in by a cooling fan, thereby suppressing the temperature increase of the rotary polygon mirror and the motor (see, for example, Patent Document 1).

In the case of an image forming apparatus having an image writing apparatus having such a configuration, if the intake port of the cooling fan is blocked, the cooling capacity is lowered and the temperature around the rotary polygon mirror is increased. Therefore, it is conceivable that the ventilation device of Patent Document 2 is applied to a cooling fan that cools the periphery of the rotary polygon mirror so that the notification means notifies the operator when the driving current of the cooling fan becomes a certain value or less. .
JP 2003-90976 (FIG. 3) JP 2002-102633 (paragraph 0025, FIG. 1)

  However, in Patent Document 2, there is no description that the image forming process is stopped after notifying the operator by the notification means. Therefore, it is considered that image formation is performed at a normal speed even after the operator is notified. . Then, the rotating polygon mirror is driven at a normal rotation speed while the cooling capacity is lowered, the temperature of the rotating polygon mirror and the motor rises, and the durability and reliability of the rotating polygon mirror are significantly deteriorated. Cause trouble in image formation.

  Accordingly, an object of the present invention is to provide an image forming apparatus capable of forming an image without causing deterioration in durability and reliability of a rotary polygon mirror and a motor for driving the rotary polygon mirror.

  In order to achieve the above object, an image forming apparatus according to claim 1 is a rotary polygon mirror that scans a laser beam on an image carrier, a motor that drives the rotary polygon mirror, and a motor that cools the motor. An image writing device having a cooling fan, fan driving current detecting means for detecting a driving current of the cooling fan, normal value storing means for storing a value of a driving current when the cooling fan is normal, and the fan driving A comparison / calculation unit that compares the drive current value detected by the current detection unit with the drive current value stored in the normal value storage unit and calculates a ratio thereof; and the comparison / calculation unit calculates The number of rotations of the motor is set according to the ratio, and image formation is performed at an image formation speed corresponding to the number of rotations.

  3. The image forming apparatus according to claim 2, wherein the comparison / calculation unit calculates a ratio with a drive current value stored in the normal value storage unit when the drive current of the cooling fan becomes a predetermined value or less. The motor rotation speed and image forming speed are set according to the calculated ratio.

  The image forming apparatus according to claim 3, wherein the image forming apparatus includes a warning unit, and the comparison / calculation unit issues a warning by the warning unit when the driving current of the cooling fan becomes a predetermined value or less. It is characterized by doing.

  According to a first aspect of the present invention, the image forming apparatus includes an image writing apparatus having a rotating polygon mirror, a motor, and a cooling fan, a fan drive current detection unit, a normal value storage unit, and a comparison / calculation unit. When the rotating polygon mirror starts to rotate by the motor, the cooling fan also starts to be driven, and the fan driving current detection means detects the driving current value of the cooling fan. The comparison / calculation means calculates the ratio by comparing the driving current value of the cooling fan detected by the fan driving current detection means with the driving current value at the time of normal driving stored in the normal value storage means, and the ratio Set the rotation speed of the motor according to. Then, the image forming speed is set to a speed corresponding to the number of rotations of the motor. As a result, the temperature rise of the rotary polygon mirror and the motor is suppressed, and image formation can be performed normally.

  3. The image forming apparatus according to claim 2, wherein the comparison / calculation unit calculates a ratio with a drive current value stored in the normal value storage unit when the drive current of the cooling fan becomes a predetermined value or less. Then, the rotational speed of the motor and the image forming speed are set according to the calculated ratio. Thereby, the temperature rise of a rotary polygon mirror and a motor can be suppressed efficiently.

  The image forming apparatus according to claim 3, wherein the image forming apparatus includes a warning unit, and the comparison / calculation unit is configured to output a warning when the driving current of the cooling fan becomes a predetermined value or less. A warning is given to warn the operator that the motor speed has been reduced. This allows the operator to know that the cooling efficiency has fallen.

  Next, the image forming apparatus of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a configuration of an image forming apparatus of the present invention. The image forming apparatus 10 is a digital copying machine having re-conveying means for automatic double-sided copying. The apparatus main body includes an image processing unit 2, an image writing device 42, an image forming unit 4, a cassette paper feeding unit 5, a fixing device 6, and a paper discharge unit 7. An automatic document feeder 20 and an image reading unit are provided on the upper part of the apparatus main body. The unit 30 is mounted.

  A document (not shown) is placed on the document table 21 of the automatic document feeder 20 with the copy surface facing upward, and is fed to the conveyance path by the conveyance unit pickup roller 25 of the automatic document reversal conveyance device 22. A document conveying unit registration roller 26 is disposed at the final end of the conveying path, and rotates in synchronization with the scanning timing of the image reading unit 30 to pass over the slit glass 27.

  The image reading unit 30 includes a scanning unit 31 including a light source and a mirror that irradiates an original through a slit glass 27, two mirrors 32 that guide reflected light, a lens 33, and an imaging device 34 such as a CCD.

  The original is read by the scanning unit 31 when passing through the slit glass 27 disposed on the upper part of the image reading unit 30, and is imaged on the image sensor 34 through the two mirrors 32 and the lens 33. The read image information of the document is processed by the image processing unit 2, and the digitized image information data is temporarily stored in a storage means (not shown).

  The image forming unit 4 includes an image carrier 1 on which an electrostatic latent image is formed. The surface of the image carrier 1 is substantially uniform in the order of operation along the outer peripheral surface of the image carrier 1. A charging device 41 for charging the electrostatic latent image, an image writing device 42 for writing the electrostatic latent image, a developing device 43 for developing the electrostatic latent image to form a toner image, and a toner image on the surface of the image carrier 1. A transfer device 44 for transferring the image onto the transfer paper P and a cleaning device 45 for cleaning the surface of the image carrier 1 after the transfer are disposed.

  On the other hand, the paper feed cassette 51 that accommodates the transfer paper P is provided with a movable plate 52 whose free end is always urged upward by an urging means such as a leaf spring, and the transfer paper placed thereon. The uppermost one of P is configured to contact the pickup roller 53. The transfer paper P in contact with the pickup roller 53 is discharged from the paper feed cassette 51, separated one by one by the separation roller 53A, and then guided to the plurality of intermediate rollers 54 and conveyed to the registration roller 55.

  The transfer paper P is fed to the transfer device 44 at a paper feed timing by a registration roller 55, and the toner image formed on the image carrier 1 is collectively transferred onto the transfer paper P by the transfer device 44. The transfer paper P onto which the toner image has been transferred is conveyed to the fixing device 6 and subjected to a fixing process. Thereafter, the transfer paper P is sandwiched between the paper discharge rollers 71 and discharged outside the apparatus, and is placed on the paper discharge table 72.

  The image forming apparatus 10 includes a manual feed tray 56 in addition to the paper feed cassette 51. It is a general usage method that the transfer paper P with high use frequency is stored in the paper feed cassette 51 and the transfer paper P with low use frequency is placed on the manual feed tray 56 each time it is used.

  FIG. 2 is a perspective view showing the configuration of the image writing apparatus. The laser beam L emitted from the semiconductor laser 42a is deflected to a scanning beam that oscillates in a range from L1 to L2 by a rotary polygon mirror 42c through a collimator lens 42b. The laser beam L deflected by the rotating polygon mirror 42 c passes through the fθ lens 42 d and the cylindrical lens 42 e and enters the surface of the image carrier 1. The rotary polygon mirror 42c is attached to the rotation shaft of a motor 42f (polygon motor) that rotates the rotary polygon mirror 42c. Further, a cooling fan 42g for cooling the motor 42f is provided behind the motor 42f.

  FIG. 3 is a block diagram of the image forming apparatus of the present invention. The cooling fan 42g sucks air from the outside of the image forming apparatus 10 and cools the motor 42f with the sucked cold air. The fan drive current detection means 81 detects the current value of the cooling fan drive current that drives the cooling fan 42g. The cooling fan 42g has a configuration in which the drive current is reduced when the intake from the outside cannot be performed for the reason of blocking the intake port or the like, and the decrease in the drive current can be detected by the fan drive current detection means 81. It is. The normal value storage means 82 stores the drive current of the cooling fan 42g when the image forming apparatus 10 is manufactured or installed.

  By comparing the current value stored in the normal value storage means 82 with the current value detected by the fan drive current detection means 81, it is possible to determine whether or not the cooling fan 42g is operating normally. The comparison / calculation means 83 compares the drive current value of the cooling fan 42g detected by the fan drive current detection means 81 with the normal drive current of the cooling fan 42g stored in the normal value storage means 82 in advance. is there. If the drive current value detected by the fan drive current detection means 81 is less than the drive current value stored in the normal value storage means 82 as a result of the comparison, the intake port of the cooling fan 42g is blocked. It is determined that the intake air amount is low.

  The apparatus control unit 84 controls the number of rotations of the motor 42f that drives the rotary polygon mirror 42c and controls each apparatus mounted on the image forming apparatus 10 to operate cooperatively.

  If the driving current value of the cooling fan 42g is equal to or less than the driving current value stored in the normal value storage means 82, if the driving is continued as it is, the durability and reliability of the rotary polygon mirror 42c may be impaired due to the temperature rise. There is. Therefore, in such a case, the comparison / calculation means 83 instructs the apparatus control unit 84 to reduce the rotational speed of the motor 42f. At the same time, it is necessary to change the driving speed of each device related to image formation, such as the rotational speed of the image carrier 1 and the transfer speed of the transfer paper P, in accordance with the rotational speed of the motor 42f. The comparison / arithmetic unit 83 instructs the apparatus control unit 84 to change the rotation speed of the motor 42f, and also changes the image forming speed to a value that matches the rotation speed of the motor 42f.

  By reducing the rotational speed of the motor 42f as described above, heat generation of the motor 42f and the rotary polygon mirror 42c can be suppressed, so that sufficient cooling can be performed with a small intake amount.

  In order to determine the rotation speed of the motor 42f, the ratio of the drive current value detected by the fan drive current detection means 81 to the drive current value stored in the normal value storage means 82 is obtained, and a certain constant is based on the ratio. There is a method of calculating the rotation speed by performing the calculation process. Further, a method of storing a list of ratios and rotation speeds corresponding to the ratios in a storage device (not shown) and determining the rotation speed with reference to the table may be considered.

  The warning means 85 warns the operator that the cooling capacity of the cooling fan 42g is reduced. When the drive current value detected by the fan drive current detection unit 81 is less than the normal drive current value, the comparison / calculation unit 83 is arranged on the front side of the image forming apparatus 10 via the warning unit 85. A message indicating that the cooling capacity of the cooling fan 42g is reduced is displayed on the operation unit (not shown). In addition to this, a warning LED or the like may be provided in the image forming apparatus 10 and the LED may be turned on or blinked when the cooling capacity of the cooling fan 42g is reduced.

  FIG. 4 is a flowchart showing a control procedure of the image forming apparatus of the present invention. When the image forming apparatus 10 is turned on or when the image forming process is started, the apparatus control unit 84 starts driving the motor 42f that rotates the rotary polygon mirror 42c (S01). Next, the device controller 84 starts the rotation of the cooling fan 42g that cools the motor 42f (S02), and the fan drive current detector 81 detects the drive current value of the cooling fan 42g. The driving of the cooling fan 42g may be configured such that a temperature sensor is provided in the motor 42f and drive control is performed according to the temperature detected by the temperature sensor.

  The comparison / calculation means 83 compares the drive current value detected by the fan drive current detection means 81 with the drive current value during normal operation stored in the normal value storage means 82 in advance (S03). If both are equal, the motor 42f is set to the normal rotation speed (S04). If the drive current value detected by the fan drive current detection means 81 is smaller as a result of the comparison in S03, the comparison / calculation means 83 determines the drive current value detected by the fan drive current detection means 81 and the normal value storage means. The ratio with the drive current value stored in 82 is obtained (S05). Further, the rotation speed of the motor 42f is obtained from the obtained ratio, and the apparatus control unit 84 sets the rotation speed calculated by the comparison / calculation means 83 in the motor 42f (S06). Next, the apparatus control unit 84 sets the image forming speed to a speed at which image formation can be performed normally by the number of rotations of the motor 42f set in S06 (S07), and the comparison / calculation unit 83 has the cooling capacity of the cooling fan 42g. A warning to the effect that the battery has been lowered is displayed on the operation unit (S08).

  The motor 42f is generally operated once the operation is started until the power of the image forming apparatus 10 is turned off. However, when the image forming process is not performed due to a request for power saving or noise reduction, the apparatus 42f It may be necessary to stop the motor 42f by the controller 84. Therefore, the comparison / calculation means 83 checks whether or not the motor 42f is in operation after setting the motor 42f to the normal rotation speed in S04 or after displaying a warning in S08 (S09). Then, the process returns to S03, and the drive current value of the cooling fan 42g is detected. When the operation of the motor 42f is stopped, the flowchart is ended.

  The present invention is not limited to application to a monochrome image forming apparatus, but can also be applied to a color image forming apparatus.

1 is a diagram illustrating a configuration of an image forming apparatus of the present invention. It is a perspective view which shows the structure of an image writing apparatus. 1 is a block diagram of an image forming apparatus of the present invention. 3 is a flowchart showing a control procedure of the image forming apparatus of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image carrier 10 Image forming apparatus 42 Image writing apparatus 42f Motor 42g Cooling fan 42c Rotating polygon mirror 81 Fan drive current detection means 82 Normal value storage means 83 Comparison / calculation means 85 Warning means

Claims (3)

An image carrier for carrying a toner image;
An image writing apparatus comprising: a rotary polygon mirror that scans the image carrier with a laser beam; a motor that drives the rotary polygon mirror; and a cooling fan that cools the motor;
Fan driving current detecting means for detecting the driving current of the cooling fan;
Normal value storage means for storing the value of the drive current when the cooling fan is normal;
A comparison / calculation unit that compares the drive current value detected by the fan drive current detection unit with the drive current value stored in the normal value storage unit and calculates a ratio thereof;
The comparison / calculation unit sets the number of rotations of the motor according to the calculated ratio, and forms an image at an image forming speed according to the number of rotations.   The comparison / calculation unit calculates a ratio with the drive current value stored in the normal value storage unit when the driving current of the cooling fan becomes a predetermined value or less, and according to the calculated ratio, The image forming apparatus according to claim 1, wherein a rotation speed of the motor and an image forming speed are set. The image forming apparatus has warning means,
3. The image forming apparatus according to claim 1, wherein the comparison / calculation unit issues a warning by the warning unit when the driving current of the cooling fan becomes a predetermined value or less.

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