JP2009276498A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of achieving high-quality image formation and coping with speeding-up by cooling a developing roller and a photoreceptor drum and preventing the scattering of toner even when changed with the lapse of time or in operating conditions. <P>SOLUTION: The image forming apparatus includes: a first ventilation means for allowing air to flow toward an image carrier or a developer carrier; a second ventilation means for allowing at least part of the flowing air to flow; and first and second air quantity adjusting parts for adjusting air flow rates of the first and second ventilation means. The image forming apparatus has a first mode, a second mode and a third mode, which are different in a ratio of the air flow rate of the second ventilation means to the air flow rate of the first ventilation means. A control means controls the first air quantity adjusting part and the second air quantity adjusting part so that the ratio of the first mode may be larger than the ratio of the second mode and the ratio of the third mode may be smaller than the ratio of the second mode. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as an electrophotographic copying machine, a printer, and a FAX, and more particularly to cooling of a member related to development and suppression of toner scattering.

  In recent years, the amount of toner used in image forming apparatuses has increased due to the spread of color and high speed, and as a result, the components involved in image formation inside the apparatus become contaminated with scattered toner, and the frequency of adversely affecting image quality has increased. .

As measures to solve this problem, a developing duct and a photosensitive drum (image carrier) are provided by providing a suction duct for sucking scattered toner and an air supply duct for sending air on the upper and lower sides of the developing roller (developer carrier). A method of forming a certain direction of airflow (air curtain) flowing from the air supply duct to the suction duct in the vicinity of the portion facing the body, and suppressing and collecting toner scattering from the developing roller with the air curtain (for example, Patent Document 1) Reference).
JP 11-327295 A

  However, since the airflow is in a certain direction in the above technology, the air curtain is effective in cooling the developing roller in the same part and suppressing the toner scattering from the developing roller. Changes in temperature, such as the number of prints, image formation (development processing) ON / OFF, image density, temperature inside the apparatus, and the like, change in the temperature of the photosensitive drum and the developing roller. The status of the scattered toner also changes.

  For this reason, the temperature of the photosensitive drum and the developing roller, which changes with the airflow in a certain direction, and the situation of the toner scattered around the photosensitive drum and the developing roller cannot be dealt with. There was a possibility that it would rise abnormally.

  For the same reason, there is a possibility that the toner scattered around the photosensitive drum and the developing roller cannot be sufficiently removed.

  As a result, an abnormality relating to image formation or an abnormality relating to development occurs, which deteriorates the image quality, and the scattered toner adheres to the photosensitive member, the developing drum, or the paper and deteriorates the image quality. There was a problem.

  In view of the above problems, the present invention not only cools the developing roller and suppresses toner scattering from the developing device, but also cools the photosensitive drum and suppresses temperature rise in the apparatus, even if there is a change over time or operating conditions. An object of the present invention is to provide an image forming apparatus capable of high speed and capable of forming a high quality image.

  The above object is achieved by the following configuration.

1. An image carrier, a developer carrier disposed opposite to the image carrier,
A first blower for flowing air toward at least one of the image carrier and the developer carrier;
A second air blowing means for flowing at least part of the air flowing toward at least one of the image carrier and the developer carrier;
A first air volume adjusting unit that adjusts a flow rate of air flowing through the first air blowing unit; a second air volume adjusting unit that adjusts a flow rate of air flowing through the second air blowing unit;
Control means for adjusting the flow rate of air flowing through the first blowing means by the first air volume adjusting section and adjusting the flow rate of air flowing through the second blowing means by the second air volume adjusting section; In an image forming apparatus having
A first mode, a second mode, and a third mode in which a ratio of a flow rate of flowing the second blowing unit to a flow rate of air flowing the first blowing unit is different;
The control means includes the first air volume so that the ratio in the first mode is larger than the ratio in the second mode and the ratio in the third mode is smaller than the ratio in the second mode. An image forming apparatus that controls an adjustment unit and the second air volume adjustment unit.

2. The first air blowing means has an opening for discharging air toward at least one of the image carrier and the developer carrier,
The second air blowing means has an opening for sucking at least a part of the air flowing toward at least one of the image carrier and the developer carrier adjacent to the opening. The image forming apparatus described in the item.

3. In the first mode, the control means increases the flow rate of air flowing through the second blowing means relative to the flow rate of air flowing through the first blowing means,
In the second mode, the flow rate of air flowing through the second blowing means is reduced relative to the flow rate of air flowing through the first blowing means,
In the third mode, the first flow rate is less than that in the second mode with respect to the flow rate of the air flowing through the first blowing unit. 3. The image forming apparatus according to item 1 or 2, wherein an air volume adjusting unit and the second air volume adjusting unit are controlled.

4). Having temperature detecting means for detecting the temperature inside the device;
The control means is set to the second mode when the temperature detecting means detects a predetermined temperature or higher during the operation of the developer carrier, and the first mode is detected when the temperature detecting means detects a temperature lower than the predetermined temperature. 4. The image forming apparatus according to any one of items 1 to 3, wherein

5. It has a counter that counts the number of prints,
The control means is in the second mode until the counter counts the first predetermined number of sheets while the developer carrying member is in operation, and the counter sets the second predetermined number of sheets larger than the first predetermined number of sheets. The image according to any one of claims 1 to 3, wherein the second mode is set until counting, and the first mode is set when the counter counts a value greater than a second predetermined number. Forming equipment.

6). The control means calculates a total amount of developer replenishment while the counter counts a predetermined number of sheets, and calculates an increase amount of the developer replenishment amount based on the sum every time the predetermined number of sheets is counted,
During the operation of the developer carrying member, the second mode is set when the increase amount is less than a predetermined increase amount, and the third mode is set when the increase amount is equal to or greater than the predetermined increase amount. The image forming apparatus according to 5 above.

  7. 7. The image forming apparatus according to claim 1, wherein the control unit sets the third mode while the developer carrying member is stopped.

  According to any one of 1 to 7 above, not only the cooling of the developing roller and the suppression of toner scattering from the developing device but also the cooling of the photosensitive drum and the increase in the internal temperature even if there is a change over time or a change in the operating condition. Therefore, it is possible to provide an image forming apparatus that can be suppressed and that is capable of high-quality image formation and that supports high speed.

  Hereinafter, an example of an embodiment according to the present invention will be described with reference to the drawings. However, the technical scope of the present invention is not limited by the terms used in this specification.

In the following explanation,
The width refers to the length of a member perpendicular to the direction in which the paper P is conveyed, and the width direction refers to the direction perpendicular to the direction in which the paper P is conveyed.

  Further, upstream means the side that is transported in the transport direction, refers to the side that has been rotated in the rotational direction, and downstream refers to the side that is transported and the side that rotates. .

  FIG. 1 is a schematic sectional view of the image forming apparatus.

  The photosensitive drum 31 as an image carrier is rotated in the direction indicated by the arrow by obtaining a rotational force from a drum driving unit (not shown).

  Around the photosensitive drum 31, a charger 32, a writing device 33, a developing device 34, a transfer device 35, a separator 36, and a cleaning device 38 are arranged in this order from the upstream side in the rotation direction.

  Thus, charging by the charger 32 and image exposure (latent image formation) by the writing device 33 are performed on the photosensitive drum 31, and the latent image is developed by the developing roller 341 of the developing device 34.

  That is, the toner adheres to the latent image and is visualized to form a toner image.

  On the other hand, the paper P, which is a transfer material, is sent out from the paper feed tray 21 of the paper feeding device 2 by the feed roller 22, is urged by the transport roller 241, passes through the transport means 24, reaches the timing roller 23, and temporarily. Stop.

  Then, the posture of the paper P is corrected by the timing roller 23.

  By re-driving the timing roller 23 synchronized with the toner image on the photosensitive drum 31, the paper P is guided from the entry guide plate 25 to the transfer region S.

  In the transfer region S, the toner image is transferred onto the paper P by the transfer device 35 to which a voltage opposite in polarity to the toner is applied, and the paper P on which the toner image has been transferred from the photosensitive drum 31 is separated by the separator 36.

  The separated paper P is transported to the fixing device 37 by a transport belt 39 provided with an air suction box 391 inside.

  Thereafter, a pressure roller 37A provided in the fixing device 37 and a heating roller 37B as a fixing roller are brought into a pressure-bonded state by a pressure-bonding mechanism 37C, and the paper P carrying the toner image is pressed and heated at the nip K. Then, the toner image is fixed on the paper P.

  After the transfer, the photosensitive drum 31 is cleaned by the cleaning device 38 and is prepared for the next image formation.

  As described above, an image is formed. In the vicinity of the developing device 34, for example, on the upper side of the developing device 34, at least one of the photosensitive drum 31 as an image carrier and the developing roller 341 as a developer carrier. A first blower 342 for flowing air and a second blower 344 for flowing at least part of the air flowed toward at least one of the photosensitive drum 31 and the developing roller 341 are disposed.

  The operation described above is controlled by a control unit C, which will be described later, which is a control means.

  Hereinafter, the 1st ventilation means 342 and the 2nd ventilation means 344 are demonstrated.

  FIG. 2 is a schematic cross-sectional view enlarging the vicinity of the developing device.

  The first air blowing means 342 and the second air blowing means 344 are each formed of a duct-shaped tube.

  Hereinafter, the first blowing unit 342 is referred to as a blowing duct 342, and the second blowing unit 344 is referred to as an exhaust duct 344.

  The positional relationship among the air duct 342, the exhaust air duct 344, and the developing device 34 is in contact with the upper side of the developing device 34 from the viewpoint of lowering the temperature inside the developing device 34 with the air (outside air) passing through the air blowing duct 342. 342 is located, and the air exhaust duct 344 is located above and in contact with the air duct 342.

  The air duct 342 and the exhaust duct 344 are adjacent to each other by a partition wall 345 which is a part of a duct-shaped cylinder, and the air duct 342 and the developing device 34 are a part of the duct-shaped cylinder and a housing of the developing device. Adjacent by a partition 346.

  The air duct 342 has an air supply port e that extends in the width direction and is separated from the surface of the developing roller 341, and an external air intake port f that takes in air from the outside of the apparatus is open on the opposite side of the air supply port e.

  The vicinity of the air supply port e of the blower duct 342 faces slightly downstream from the center of the developing roller 341.

  An intake fan F1 is provided between the air inlet e and the outside air inlet f to suck air from the outside air inlet f (outside the apparatus) and release the air from the air outlet e.

  Accordingly, an air flow from the outside air intake port f to the air supply port e is generated by the intake fan F1, and at least one of the photosensitive drum 31 and the developing roller 341 can be cooled.

  The air flow (airflow) will be described in detail later.

  Further, a developer regulating plate 343 is disposed at the air supply port e of the air duct 342 so as to partially cover the air outlet e.

  Therefore, the developer regulating plate 343 is cooled by the outside air by the air flowing through the air duct 342 and the adhered toner is wiped out.

  The air exhaust duct 344 has an air intake g that is spaced apart from the surface of the developing roller 341 and extends in the width direction, and an air exhaust h that discharges air sucked to the outside of the apparatus is opened on the opposite side of the air intake g. .

  In order to prevent toner collected outside the apparatus from being scattered inside and outside the apparatus, it is preferable to provide a filter (not shown) for collecting toner etc. at the exhaust port h.

  The direction of the exhaust duct 344 near the intake port g is downstream of the air supply port e, for example, near the nip region N between the developing roller 341 and the photosensitive drum 31.

  The air inlet e of the air duct 342 and the air inlet g of the air exhaust duct 344 are separated from each other by the thickness of the partition wall 345 and open in an adjacent state.

  And between the inlet port g and the exhaust port h, the exhaust fan F2 for exhausting the air attracted | sucked from the inlet port g from the external air intake port f (outside the apparatus) is provided.

  Accordingly, an air flow toward the periphery of the photosensitive drum 31 and the periphery of the developing roller 341 is generated by the intake fan F1, and a part of the air flow toward the periphery of the photosensitive drum 31 and the periphery of the developing roller 341 is sucked by the exhaust fan F2.

  By these air currents, the toner floating around at least one of the photosensitive drum 31 and the developing roller 341 can be sucked to suppress toner scattering, and at least one of the photosensitive drum 31 and the developing roller 341 can be cooled. Become.

  The air flow (airflow) indicated by the broken line will be described in detail later.

  An air supply port e of the air duct 342 is disposed on the upstream side of the developing roller 341, and an air intake port g of the air exhaust duct 344 is disposed on the downstream side. The uniformity of the thickness of the toner carried on the developing roller 341 can be maintained without being disturbed.

  The air duct 342 is provided with an air volume adjusting valve B1 as a first air volume adjusting section between the air supply port e and the intake fan F1, and the flow rate (air volume) of the air flowing through the air duct 342 is controlled by the control section C. It is controlled by.

  Note that an air volume adjustment valve B1 may be provided between the intake fan F1 and the outside air intake port f.

  The exhaust air duct 344 is provided with an air volume adjusting valve B2 as a second air volume adjusting unit between the intake port g and the exhaust fan F2, and the flow rate (air volume) of the air flowing through the exhaust air duct 344 is high. It is controlled by the control unit C.

  An air volume adjusting valve B2 may be provided between the exhaust fan F2 and the exhaust port h.

  A temperature sensor T for measuring the temperature inside the image forming apparatus is provided in the vicinity of the photosensitive drum 31 and the developing device 34 (for example, in the vicinity of the nip region N), and the measured value is input to the control unit C. Controls the air volume adjusting valve B1 and the air volume adjusting valve B2 according to the measured temperature inside the image forming apparatus.

  FIG. 3 is a block diagram of control relating to cooling of the developing roller and the photosensitive drum and suppression of toner scattering.

  Hereinafter, a control configuration relating to cooling of the developing roller 341 and the photosensitive drum 31 and suppression of toner scattering will be described.

  The control unit C of the image forming apparatus includes a non-volatile storage unit M (to be described later) in which a control program and the like of the entire image forming apparatus are stored in advance, a CPU that sequentially reads out the control program and stores it in the RAM, and executes various data. RAM, the interface unit I / O for interfacing with the above-described various sensors and various input / output members, and the counter C1 for counting the number of printed sheets.

In the non-volatile storage means M, a control program for the entire image forming apparatus, a program described in a flowchart to be described later,
Predetermined temperature information related to the temperature inside the image forming apparatus, which is a timing for switching the control contents relating to cooling of the developing roller 341 and the photosensitive drum 31 and toner scattering suppression;
First predetermined number information relating to the number of prints processed after toner bottle replacement, and the number of prints larger than the first predetermined number information, which are timings for switching the control contents relating to cooling of the developing roller 341 and the photosensitive drum 31 and suppression of toner scattering. A second predetermined number of pieces of information,
From the first predetermined amount and the first predetermined amount regarding the increase amount of the developer replenishment amount (toner replenishment increase amount), which is the timing for switching the control contents relating to the cooling of the developing roller 341 and the photosensitive drum 31 and the toner scattering suppression. A large second predetermined amount and a third predetermined amount larger than the second predetermined amount are stored in advance.

  During execution of the control program for the entire image forming apparatus, the CPU reads a program described in a flowchart described later as necessary, and executes control related to cooling of the developing roller and the photosensitive drum and suppression of toner scattering.

  The counter C1 is reset to 0 when the CPU replaces the toner (when the toner bottle is replaced), and increments by one each time printing (development) is performed during execution of the image forming process (printing process). Is done.

  The temperature sensor T measures the temperature inside the image forming apparatus, and the measured value is input to the control unit C.

  The intake fan F1 is ON / OFF controlled by the controller C.

  The exhaust fan F2 is ON / OFF controlled by the control unit C.

  The air volume adjusting valve B <b> 1 is controlled by the control unit C so that the opening amount of the valve is controlled to adjust the flow rate (air volume) of the air flowing through the air duct 342.

  The air volume adjusting valve B <b> 2 is controlled by the control unit C so that the opening amount of the valve is controlled to adjust the flow rate (air volume) of the air flowing through the exhaust duct 344.

  Note that when the air flow rate (air flow rate) is adjusted without using the air flow rate adjustment valve B1 and the air flow rate adjustment valve B2, the rotation speeds of the intake fan F1 and the exhaust fan F2 are controlled.

  Hereinafter, control related to cooling of the developing roller and the photosensitive drum and suppression of toner scattering will be described with reference to a flowchart.

  In this, the unit representing the flow rate is described as “point”, but the ratio of the flow rate of the air flowing through the air duct 342 and the exhaust duct 344 is the first mode, the second mode, and the third mode. It is important that they differ from each other, and the specific flow rate varies depending on the apparatus conditions. Therefore, for example, the concept of “points” is used without using units such as cubic meters / second.

  FIG. 4 is a flowchart of control according to the temperature related to cooling of the developing roller and the photosensitive drum and suppression of toner scattering.

  This flow adjusts the flow rate (air volume) of the air flowing through the air duct 342 and the exhaust duct 344 according to the temperature inside the image forming apparatus, thereby cooling the developing roller 341 and the photosensitive drum 31 and suppressing toner scattering. It is preferably used when aiming.

  The first mode, the second mode, and the third mode have different ratios of the flow rate of flowing the exhaust duct 344 to the flow rate of air flowing through the blower duct 342.

1. Determination of continuation / stop of development processing (step S101)
It is determined whether or not development processing, that is, image formation is to be continued. If so (Yes), the process proceeds to the next step. If not (No), the process proceeds to step S108.

2. Detection of temperature sensor T (step S102)
The measured value of the temperature sensor T that measures the temperature inside the image forming apparatus is taken in, and the process proceeds to the next step.

3. Comparison determination between measured value and predetermined temperature (step S103)
Read predetermined temperature information inside the image forming apparatus from the non-volatile storage means M,
The predetermined temperature information (for example, 35 ° C.) is compared with the measured value of the temperature sensor T captured in step S102. If the measured value of the temperature sensor T is less than the predetermined temperature information (for example, 35 ° C.) (Yes), the next step is performed. The process proceeds to step S106 if the measured value of the temperature sensor T is equal to or higher than predetermined temperature information (for example, 35 ° C.).

4). First mode setting (step S104)
Since the developing device 34 is in operation and the inside of the apparatus is below a predetermined temperature,
The flow rate of air flowing through the exhaust duct 344 is increased relative to the flow rate of air flowing through the air duct 342 so that the ratio in the first mode is greater than the ratio in the second mode. Set the mode and go to the next step.

5. Cooling and toner scattering suppression in the first mode (step S105)
The air flow rate adjustment valve B1 and the air flow rate adjustment valve B2 are adjusted, and the flow rate of air flowing through the exhaust air duct 344 is increased (eg, 0.6 points) with respect to the flow rate of air flowing through the blower duct 342 (eg, 0.5 points). point).

  By adjusting the flow rate, substantially all of the wind flowing through the air duct 342 is sucked by the air exhaust duct 344 and proceeds to the end.

6). Second mode setting (step S106)
Since the developing device 34 is in operation and the inside of the apparatus is above a predetermined temperature,
The flow rate of air flowing through the air duct 342 is such that the ratio in the first mode is larger than the ratio in the second mode and the ratio in the third mode is smaller than the ratio in the second mode. On the other hand, the second mode in which the flow rate of the air flowing through the exhaust duct 344 is reduced is set, and the process proceeds to the next step.

7). Cooling and toner scattering suppression in the second mode (step S107)
The air flow rate adjustment valve B1 and the air flow rate adjustment valve B2 are adjusted to reduce the flow rate of air flowing through the exhaust duct 344 relative to the flow rate of air flowing through the air duct 342 (eg, 1.0 point) (eg, 0.6). point).

  By adjusting the flow rate, approximately half of the wind flowing through the air duct 342 is sucked by the exhaust duct 344, and as a result, the wind flowing through the air duct 342 and the wind flowing in the direction of the exhaust drum 344 And divert in the two directions.

8). Third mode setting (step S108)
Since the developing unit 34 is stopped, the exhaust duct 344 is caused to flow with respect to the flow rate of the air flowing through the air duct 342 so that the ratio in the third mode is smaller than the ratio in the second mode. The third mode in which the flow rate of air to be generated is made lower than that in the second mode is set, and the process proceeds to the next step.

9. Cooling and toner scattering suppression in the third mode (step S109)
The air volume adjusting valve B1 and the air volume adjusting valve B2 are adjusted to reduce the flow rate of the air flowing through the exhaust air duct 344 relative to the flow rate of the air flowing through the air duct 342.

  For example, the exhaust duct 344 is set to 0.0 point (cut off) with respect to the air duct 342 and 1.0 point.

  By adjusting the flow rate, the wind flowing through the air duct 342 is not sucked by the exhaust air duct 344 at all, and as a result, all the air flowing through the air duct 342 flows toward the photosensitive drum 31 and proceeds to the end.

  As described above, the flow described with reference to FIG. 4 increases the temperature of the photosensitive drum and the developing roller due to changes over time and operating conditions, and the status of toner scattered around the photosensitive drum and the developing roller. In response to the change, the photosensitive drum 31 or the developing roller 341 is cooled to suppress an increase in the internal temperature, and at the same time, the toner scattered and floating around the developing roller 341 and the photosensitive drum 31 is sucked and exhausted. Is possible.

  In the first mode, it is possible to cool the developing roller 341 and to suck and exhaust the toner scattered and floating around the developing roller 341 and the photosensitive drum 31.

  In the first mode, as described above, almost all of the air flowing through the air duct 342 is sucked by the air exhaust duct 344, which is close to the developing device described in the background art and is the default.

  In the second mode, in particular, the photosensitive drum 31 and the developing roller 341 can be cooled, and at the same time, the toner scattered and floating around the developing roller 341 and the photosensitive drum 31 can be sucked and exhausted.

  In the third mode, in particular, it is possible to suppress the cooling of the photosensitive drum 31 and the rise in the in-machine temperature.

  FIG. 5 is a flowchart of control according to the number of prints related to cooling of the developing roller and the photosensitive drum and suppression of toner scattering.

  This flow adjusts the flow rate (air volume) of the air flowing through the blower duct 342 and the exhaust duct 344 according to the number of prints on which image formation has been performed, thereby cooling the developing roller 341 and the photosensitive drum 31 and scattering the toner. It is preferably used when suppressing the problem.

  The first mode, the second mode, and the third mode have different ratios of the flow rate of flowing the exhaust duct 344 to the flow rate of air flowing through the blower duct 342.

1. Determination of continuation / stop of development processing (step S201)
Since it is the same as the above-mentioned step S101, description is abbreviate | omitted.

2. Reading the number of prints (step S202)
The count value of the counter C1 for counting the number of prints is read and the process proceeds to the next step.

3. Determination of whether the number of prints is less than the first predetermined number (step S203)
Read from the ROM first predetermined number information (for example, 50,000 sheets) relating to the number of prints processed after the toner bottle replacement, which is the timing for switching the control contents relating to the cooling of the developing roller 341 and the photosensitive drum 31 and the suppression of toner scattering. The count value read in step S202 is compared with the first predetermined number.

  If the count value (number of printed sheets) is less than the first predetermined number of sheets information (Yes), the process proceeds to the next step, and if it is more than (No), the process proceeds to step S206.

4). Second mode setting (step S204)
Since the developing device 34 is in operation and the number of prints is less than the first predetermined number,
The air duct 342 is caused to flow by the air volume adjusting valve B1 so that the ratio in the first mode is larger than the ratio in the second mode and the ratio in the third mode is smaller than the ratio in the second mode. The second mode is set in which the flow rate of the air flowing through the exhaust duct 344 is reduced by the air flow rate adjustment valve B2 with respect to the flow rate of the air, and the process proceeds to the next step.

5. Cooling and toner scattering suppression in the second mode (step S205)
The air flow rate adjustment valve B1 and the air flow rate adjustment valve B2 are adjusted, and the flow rate of air flowing through the exhaust duct 344 is reduced (eg, 0.6 points) with respect to the flow rate of air flowing through the blower duct 342 (eg, 1.0 point). ).

  By adjusting the flow rate, approximately 60% of the wind flowing through the air duct 342 is sucked by the exhaust duct 344, and as a result, the wind flowing through the air duct 342 in the direction of the photosensitive drum 31 (approximately 40%) and the exhaust air are exhausted. The air is diverted in two directions, with the wind flowing in the direction of the duct 344, and proceeds to the end.

6). Judgment whether or not the number of prints is less than the second predetermined number (step S206)
Second predetermined number information (for example, 150,000 sheets) that is larger than the first predetermined number of sheets information (for example, 50,000 sheets) is read from the ROM, and the count value read in step S202 and the second predetermined number of sheets (for example, for example) 150,000 sheets).

  If the count value (number of printed sheets) is less than the second predetermined number of sheets information (Yes), the process proceeds to the next step, and if it is more than (No), the process proceeds to step S209.

7). Second mode setting (step S207)
Since the developing device 34 is in operation and the number of prints is, for example, 50,000 or more and less than 150,000,
The flow rate of air flowing through the air duct 342 is such that the ratio in the first mode is larger than the ratio in the second mode and the ratio in the third mode is smaller than the ratio in the second mode. On the other hand, the second mode in which the flow rate of the air flowing through the exhaust duct 344 is reduced is set, and the process proceeds to the next step.

8). Cooling and toner scattering suppression in the second mode (step S208)
The air flow rate adjustment valve B1 and the air flow rate adjustment valve B2 are adjusted, and the flow rate of air flowing through the exhaust duct 344 is reduced (eg, 0.9 points) with respect to the flow rate of air flowing through the blow duct 342 (eg, 1.0 point). point).

  By adjusting the flow rate, approximately 90% of the wind flowing through the air duct 342 is sucked by the exhaust duct 344, and as a result, the wind flowing through the air duct 342 in the direction of the photosensitive drum 31 (approximately 10%) and the exhaust air are exhausted. The air is diverted in two directions, with the wind flowing in the direction of the duct 344, and proceeds to the end.

9. First mode setting (step S209)
Since the developing device 34 is in operation and the number of printed sheets is 150,000 or more,
The flow rate of air flowing through the exhaust duct 344 is increased relative to the flow rate of air flowing through the air duct 342 so that the ratio in the first mode is greater than the ratio in the second mode. Set the mode and go to the next step.

10. Cooling and toner scattering suppression in the first mode (step S210)
The air flow rate adjustment valve B1 and the air flow rate adjustment valve B2 are adjusted, and the flow rate of air flowing through the exhaust duct 344 is increased (eg, 1.2 points) relative to the flow rate of air flowing through the blower duct 342 (eg, 1.0 point). point).

  By adjusting the flow rate, substantially all of the wind flowing through the air duct 342 is sucked by the air exhaust duct 344 and proceeds to the end.

11. Third mode setting (step S211)
Since it is the same as the above-mentioned step S108, description is abbreviate | omitted.

12 Cooling and toner scattering suppression in the third mode (step S212)
The description is omitted because it is similar to step S109 described above.

In the above flow, the print number of 150,000 or more in step S106 is further divided into 150,000 or more and less than 200,000,
When the number of printed sheets is 150,000 or more and less than 200,000, the first mode is set, and the air volume adjusting valve is set with respect to the air flow rate (for example, 1.0 point) flowing through the air duct 342 by the air volume adjusting valve B1. The flow rate of the air flowing through the exhaust duct 344 may be increased by B2 (for example, 1.2 points).

  As described above, the flow described with reference to FIG. 5 increases the temperature of the photosensitive drum and the developing roller due to changes over time and operating conditions, and the state of toner scattered around the photosensitive drum and the developing roller. In response to the change, the photosensitive drum 31 or the developing roller 341 is cooled to suppress an increase in the internal temperature, and at the same time, the toner scattered and floating around the developing roller 341 and the photosensitive drum 31 is sucked and exhausted. Is possible.

  In the first mode, in particular, the developing roller 341 can be cooled, and the toner scattered and floating around the developing roller 341 and the photosensitive drum 31 can be sucked and exhausted.

  In the first mode, as described above, almost all of the air flowing through the air duct 342 is sucked by the air exhaust duct 344, which is close to the developing device described in the background art and is the default.

  In the second mode, in particular, the photosensitive drum 31 and the developing roller 341 can be cooled, and at the same time, the toner scattered and floating around the developing roller 341 and the photosensitive drum 31 can be sucked and exhausted.

  In the third mode, in particular, it is possible to suppress the cooling of the photosensitive drum 31 and the rise in the in-machine temperature.

  FIG. 6 is a flowchart of control according to the developer replenishment amount for cooling the developing roller and the photosensitive drum and suppressing toner scattering.

  FIG. 7 is a flowchart subsequent to FIG.

  6 and 7, the flow rate (air volume) of the air flowing through the air duct 342 and the exhaust duct 344 is adjusted according to the increase in the developer replenishment amount, so that the developing roller 341 and the photosensitive drum 31 are adjusted. It is suitably used for cooling the toner and suppressing toner scattering.

  The first mode, the second mode, and the third mode have different ratios of the flow rate of flowing the exhaust duct 344 to the flow rate of air flowing through the blower duct 342.

  The control unit C calculates the total amount of developer replenishment while the counter C1 counts 100, and each time a predetermined number of sheets (for example, 100 sheets) is counted, the amount of increase in the developer replenishment amount is calculated based on the total. calculate.

  Specifically, every time the counter C1 counts a predetermined number of sheets (for example, 100 sheets), for example, based on the rotation amount of the developing drum, etc., the total amount (total) of toner used during counting 100 sheets of prints is calculated and stored in the RAM. And so on.

  Then, the total amount of the current toner is subtracted from the total amount of the previous toner, and the latest increase amount of the developer replenishment amount is calculated and stored in the RAM as the toner replenishment increase amount.

1. Determination of continuation / stop of development processing (step S301)
Since it is the same as the above-mentioned step S101, description is abbreviate | omitted.

2. Reading the number of prints (step S302)
The description is omitted because it is similar to step S202 described above.

3. Toner replenishment increase amount reading (step S303)
The toner replenishment increase amount is read from the RAM, and the process proceeds to the next step.

4). Judgment whether the number of prints is less than the first predetermined number (step S304)
The count value (number of prints) read in step S302 and the first predetermined number information (for example, 50,000) relating to the number of prints processed after the toner bottle replacement from the ROM are read, and the count value (number of prints) and the first A predetermined number (for example, 50,000) is compared.

  If the count value (number of prints) is less than the first predetermined number of sheets (for example, 50,000) (Yes), the process proceeds to the next step, and if not (No), the process proceeds to step S310.

5. Determination of whether or not the toner replenishment increase amount is less than a second predetermined amount (step S305)
The toner replenishment increase amount read in step S303 and the second predetermined amount (for example, 6 g) greater than the first predetermined amount (for example, 3 g) related to the increase in the toner replenishment amount are read from the ROM. 2 Compare with a predetermined amount (for example, 6 g).

  If the toner replenishment increase amount is less than the second predetermined amount (for example, 6 g) (Yes), the process proceeds to the next step, and if it is not less than (No), the process proceeds to step S308.

6). Second mode setting (step S306)
Since the developing device 34 is in operation and the toner replenishment increase amount is less than a second predetermined amount (for example, 6 g),
The flow rate of air flowing through the air duct 342 is such that the ratio in the first mode is larger than the ratio in the second mode and the ratio in the third mode is smaller than the ratio in the second mode. On the other hand, the second mode in which the flow rate of the air flowing through the exhaust duct 344 is reduced is set, and the process proceeds to the next step.

7). Cooling and toner scattering suppression in the second mode (step S307)
The air flow rate adjustment valve B1 and the air flow rate adjustment valve B2 are adjusted to reduce the flow rate of air flowing through the exhaust duct 344 relative to the flow rate of air flowing through the air duct 342 (eg, 1.0 point) (eg, 0.6). point).

  By adjusting the flow rate, approximately 60% of the wind flowing through the air duct 342 is sucked by the exhaust duct 344, and as a result, the wind flowing through the air duct 342 in the direction of the photosensitive drum 31 (approximately 40%) and the exhaust air are exhausted. The air is diverted in two directions, with the wind flowing in the direction of the duct 344, and proceeds to the end.

8). Second mode setting (step S308)
Since the developing device 34 is in operation and the toner replenishment increase amount is equal to or greater than a second predetermined amount (for example, 6 g),
The flow rate of air flowing through the air duct 342 is such that the ratio in the first mode is larger than the ratio in the second mode and the ratio in the third mode is smaller than the ratio in the second mode. On the other hand, the second mode in which the flow rate of the air flowing through the exhaust duct 344 is reduced is set, and the process proceeds to the next step.

9. Cooling and toner scattering suppression in the second mode (step S309)
The air flow rate adjustment valve B1 and the air flow rate adjustment valve B2 are adjusted, and the flow rate of air flowing through the exhaust duct 344 is reduced (eg, 0.9 points) with respect to the flow rate of air flowing through the blow duct 342 (eg, 1.0 point). point).

  By adjusting the flow rate, approximately 90% of the wind flowing through the air duct 342 is sucked by the exhaust duct 344, and as a result, the wind flowing through the air duct 342 in the direction of the photosensitive drum 31 (approximately 10%) and the exhaust air are exhausted. The air is diverted in two directions, with the wind flowing in the direction of the duct 344, and proceeds to the end.

10. Determination of whether the number of prints is less than the second predetermined number (step S310)
The count value (number of printed sheets) read in step S302 and the second predetermined number of sheets information (for example, 150,000 sheets) larger than the first predetermined number of sheets information (for example, 50,000 sheets) are read from the ROM, and the count value (printed number) is printed. Number of sheets) and a second predetermined number (for example, 150,000 sheets) are compared.

  If the count value (number of prints) is less than the second predetermined number (for example, 150,000) (Yes), the process proceeds to the next step, and if not (No), the process proceeds to step S319.

11. Determination of whether or not the toner replenishment increase amount is less than a first predetermined amount (step S311)
The toner replenishment increase amount read in step S303 and a first predetermined amount (for example, 3 g) relating to the increase in toner replenishment amount are read from the ROM, and the toner replenishment increase amount is compared with the first predetermined amount.

  If the toner replenishment increase amount is less than the first predetermined amount (for example, 3 g) (Yes), the process proceeds to the next step, and if it is not less than (No), the process proceeds to step S314.

12 Second mode setting (step S312)
Since the developing device 34 is in operation and the toner replenishment increase amount is less than a first predetermined amount (for example, 3 g),
The flow rate of air flowing through the air duct 342 is such that the ratio in the first mode is larger than the ratio in the second mode and the ratio in the third mode is smaller than the ratio in the second mode. On the other hand, the second mode in which the flow rate of the air flowing through the exhaust duct 344 is reduced is set, and the process proceeds to the next step.

13. Cooling and toner scattering suppression in the second mode (step S313)
Since it is the same as step S307 described above, description thereof is omitted.

14 Determination of whether or not the toner replenishment increase amount is less than a second predetermined amount (step S314)
The toner supply increase amount read in step S303 and a second predetermined amount (for example, 6 g) are read from the ROM, and the toner supply increase amount and the second predetermined amount are compared.

  If the toner replenishment increase amount is less than the second predetermined amount (for example, 6 g) (Yes), the process proceeds to the next step, and if it is not less than (No), the process proceeds to step S319.

15. Second mode setting (step S315)
Since the developing device 34 is in operation and the toner replenishment increase amount is not less than the first predetermined amount (for example, 3 g) and less than the second predetermined amount (for example, 6 g),
The flow rate of air flowing through the air duct 342 is such that the ratio in the first mode is larger than the ratio in the second mode and the ratio in the third mode is smaller than the ratio in the second mode. On the other hand, the second mode in which the flow rate of the air flowing through the exhaust duct 344 is reduced is set, and the process proceeds to the next step.

16. Cooling and toner scattering suppression in the second mode (step S316)
The air flow rate adjustment valve B1 and the air flow rate adjustment valve B2 are adjusted, and the flow rate of air flowing through the exhaust duct 344 is reduced (eg, 0.9 points) with respect to the flow rate of air flowing through the blow duct 342 (eg, 1.0 point). point).

  By adjusting the flow rate, approximately 90% of the wind flowing through the air duct 342 is sucked by the exhaust duct 344, and as a result, the wind flowing through the air duct 342 in the direction of the photosensitive drum 31 (approximately 10%) and the exhaust air are exhausted. The air is diverted in two directions, with the wind flowing in the direction of the duct 344, and proceeds to the end.

17. First mode setting (step S317)
Since the developing device 34 is in operation and the number of prints is equal to or greater than a second predetermined number (for example, 150,000),
The flow rate of air flowing through the exhaust duct 344 is increased relative to the flow rate of air flowing through the air duct 342 so that the ratio in the first mode is greater than the ratio in the second mode. Set the mode and go to the next step.

18. Cooling and toner scattering suppression in the first mode (step S318)
Since it is the same as the above-mentioned step S315, description is abbreviate | omitted.

19. First mode setting (step S319)
Since the developing device 34 is in operation and the number of prints is equal to or greater than a second predetermined number (for example, 150,000),
The flow rate of air flowing through the exhaust duct 344 is increased relative to the flow rate of air flowing through the air duct 342 so that the ratio in the first mode is greater than the ratio in the second mode. Set the mode and go to the next step.

20. Cooling and toner scattering suppression in the first mode (step S320)
The air flow rate adjustment valve B1 and the air flow rate adjustment valve B2 are adjusted, and the flow rate of air flowing through the exhaust duct 344 is increased (eg, 1.2 points) relative to the flow rate of air flowing through the blower duct 342 (eg, 1.0 point). point).

  By adjusting the flow rate, substantially all of the wind flowing through the air duct 342 is sucked by the air exhaust duct 344 and proceeds to the end.

21. Third mode setting (step S321)
Since it is the same as the above-mentioned step S108, description is abbreviate | omitted.

22. Cooling and toner scattering suppression in the third mode (step S322)
Since it is the same as step S109 described above, description thereof is omitted.

  As described above with reference to FIGS. 5 to 7, the temperature rise of the photosensitive drum and the developing roller due to the change over time and the operation status, and the situation of the toner scattered around the photosensitive drum and the developing roller. In response to the change, the photosensitive drum 31 or the developing roller 341 is cooled to suppress an increase in the internal temperature, and at the same time, the toner scattered and floating around the developing roller 341 and the photosensitive drum 31 is sucked and exhausted. Is possible.

  In the first mode, in particular, the developing roller 341 can be cooled, and the toner scattered and floating around the developing roller 341 and the photosensitive drum 31 can be sucked and exhausted.

  In the first mode, as described above, almost all of the air flowing through the air duct 342 is sucked by the air exhaust duct 344, which is close to the developing device described in the background art and is the default.

  In the second mode, in particular, the photosensitive drum 31 and the developing roller 341 can be cooled, and at the same time, the toner scattered and floating around the developing roller 341 and the photosensitive drum 31 can be sucked and exhausted.

  In the third mode, in particular, it is possible to suppress the cooling of the photosensitive drum 31 and the rise in the in-machine temperature.

  4 to 7, the air flowing through the air duct 342 flows to the exhaust duct 344 by reducing the flow rate of the air flowing through the air exhaust duct 344 with respect to the flow rate of air flowing through the air duct 342. The second mode characterized in that it can be divided into an air current and an air current flowing through the photosensitive drum 31 will be described in detail.

  In the second mode, the photosensitive drum 31 and the developing roller 341 are cooled by dividing the airflow flowing through the exhaust duct 344 and the airflow flowing through the photosensitive drum 31, and at the same time, the photosensitive drum 31 and the developing roller 341. It is possible to suck and exhaust the toner that is scattered and floating around the area.

Further, an amount of reducing the flow rate of air flowing through the exhaust duct 344 relative to the flow rate of air flowing through the air duct 342 in the second mode,
As described in steps S205 and S208 in the flow of FIG. 5, and in steps S307 and 313 and steps S309 and S318 in the flows of FIGS. 6 and 7, for example, two steps or more may be possible.

  For example, taking step S205 and step S208 in the flow of FIG.

In step S205, when the print is less than 50,000 sheets, the flow rate of the air flowing through the exhaust duct 344 is set to 0.6 point, and the flow to the photosensitive drum 31 is set to (1.0−0.6 =) 0.4 point. by doing,
The photosensitive drum 31 can be cooled at a flow rate of 0.4 point, and further, the toner scattered and floating around the photosensitive drum 31 and the developing roller 341 can be sucked and exhausted at a flow rate of 0.6 point. Become.

In step S208, when 50,000 sheets are printed or more and less than 150,000 sheets are printed, the flow rate of the air flowing through the exhaust duct 344 is 0.9 point, and the flow to the photosensitive drum 31 is (1.0-0. 9 =) By setting 0.1 points,
The photosensitive drum 31 can be cooled at a flow rate of 0.1 point, and the toner scattered and floating around the photosensitive drum 31 and the developing roller 341 can be sucked and exhausted at a flow rate of 0.9 point. As a result, more toner can be sucked and exhausted.

Thus, in the second mode, when the flow rate of air flowing through the exhaust duct 344 is reduced relative to the flow rate of air flowing through the blower duct 342,
By setting the flow rate of the air flowing through the exhaust duct 344 in a plurality of stages, it is possible to cool the developing roller 341 and the photosensitive drum 31 more finely and suppress toner scattering than in a single stage.

  Although the modes have been described as the first to third types, the modes may be divided into more modes as described above.

  For example, in the second mode, the flow rate of the air flowing through the exhaust duct 344 is decreased in a plurality of steps according to the temperature inside the apparatus, the number of prints, or the amount of toner replenishment with respect to the flow rate of the air flowing through the air duct 342 The mode may be divided into three or more modes as a whole.

  By doing so, it is possible to more precisely cool the developing roller 341 and the photosensitive drum 31 and suppress toner scattering.

Further, as a configuration for adjusting the flow rate of the air flowing through the exhaust duct 344 as the second blowing unit with respect to the flow rate of the air flowing through the blowing duct 342 as the first blowing unit, the air volume adjusting valve B1 and the air volume adjustment are adjusted. Although the structure adjusted with valve B2 was demonstrated,
The air flow adjustment valve B1 and the air flow adjustment valve B2 may be eliminated, and the flow rate of air flowing through the air duct 342 as the first air blowing means may be performed by the intake fan F1 whose rotation speed is controlled by the control unit C. ,
You may perform the flow volume of the air which flows the ventilation duct 344 which is a 2nd ventilation means with the exhaust fan F2 by which the rotation speed was controlled by the control part C. FIG.

  In this case, it is possible to measure the air flow rate with respect to the rotational speed of the fan in advance, store the relationship information indicating these relationships in the nonvolatile storage means M, and read the relationship information as necessary.

  As a result, the air volume adjusting valve B1 and the air volume adjusting valve B2 are not required, and the configuration is simplified.

  As described above, in the first mode, substantially all of the wind flowing through the air duct 342 is sucked by the exhaust duct 344, and in the third mode, the air flowing through the air duct 342 is substantially exhausted by the exhaust duct 344. As a result, all the air flowing through the air blowing duct 342 flows in the direction of the photosensitive drum 31.

Also in the first mode and the third mode, the air flow rate adjustment valve B1 and the air flow rate adjustment valve B2 are abolished, and the flow rate of the air flowing through the blower duct 342 as the first blower means is controlled by the control unit C. May be performed by the controlled intake fan F1,
You may perform the flow volume of the air which flows the ventilation duct 344 which is a 2nd ventilation means with the exhaust fan F2 by which the rotation speed was controlled by the control part C. FIG.

1 is a schematic sectional view of an image forming apparatus. 2 is a schematic cross-sectional view enlarging the vicinity of a developing device. FIG. 5 is a block diagram of control related to cooling of a developing roller and a photosensitive drum and suppression of toner scattering. FIG. 6 is a flowchart of control according to a temperature related to cooling of a developing roller and a photosensitive drum and toner scattering suppression. FIG. 6 is a flowchart of control according to the number of prints related to cooling of a developing roller and a photosensitive drum and suppression of toner scattering. FIG. 6 is a flowchart of control according to a developer replenishment amount related to cooling of a developing roller and a photosensitive drum and suppression of toner scattering. FIG. 7 is a flowchart subsequent to FIG. 6.

Explanation of symbols

31 Photosensitive drum 34 Developer 341 Developing roller 342 Air duct 344 Exhaust duct B1 Air volume adjusting valve B2 Air volume adjusting valve C Controller C1 Counter e Air supply port f Outside air intake port g Air intake port h Air exhaust port F1 Air intake fan F2 Exhaust fan N Nip area T Temperature sensor

Claims (7)

An image carrier, a developer carrier disposed opposite to the image carrier,
A first blower for flowing air toward at least one of the image carrier and the developer carrier;
A second air blowing means for flowing at least part of the air flowing toward at least one of the image carrier and the developer carrier;
A first air volume adjusting unit that adjusts a flow rate of air flowing through the first air blowing unit; a second air volume adjusting unit that adjusts a flow rate of air flowing through the second air blowing unit;
Control means for adjusting the flow rate of air flowing through the first blowing means by the first air volume adjusting section and adjusting the flow rate of air flowing through the second blowing means by the second air volume adjusting section; In an image forming apparatus having
A first mode, a second mode, and a third mode in which a ratio of a flow rate of flowing the second blowing unit to a flow rate of air flowing the first blowing unit is different;
The control means includes the first air volume so that the ratio in the first mode is larger than the ratio in the second mode and the ratio in the third mode is smaller than the ratio in the second mode. An image forming apparatus that controls an adjustment unit and the second air volume adjustment unit. The first air blowing means has an opening for discharging air toward at least one of the image carrier and the developer carrier,
The second air blowing unit includes an opening for sucking at least a part of the air flowing toward at least one of the image carrier and the developer carrier adjacent to the opening. The image forming apparatus according to 1. In the first mode, the control means increases the flow rate of air flowing through the second blowing means relative to the flow rate of air flowing through the first blowing means,
In the second mode, the flow rate of air flowing through the second blowing means is reduced relative to the flow rate of air flowing through the first blowing means,
In the third mode, the first flow rate is less than that in the second mode with respect to the flow rate of the air flowing through the first blowing unit. The image forming apparatus according to claim 1, wherein an air volume adjusting unit and the second air volume adjusting unit are controlled. Having temperature detecting means for detecting the temperature inside the device;
The control means is set to the second mode when the temperature detecting means detects a predetermined temperature or higher during the operation of the developer carrier, and the first mode is detected when the temperature detecting means detects a temperature lower than the predetermined temperature. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. It has a counter that counts the number of prints,
The control means is in the second mode until the counter counts the first predetermined number of sheets while the developer carrying member is in operation, and the counter sets the second predetermined number of sheets larger than the first predetermined number of sheets. 4. The method according to claim 1, wherein the second mode is set until counting, and the first mode is set when the counter counts a value greater than a second predetermined number of sheets. 5. Image forming apparatus. The control means calculates a total amount of developer replenishment while the counter counts a predetermined number of sheets, and calculates an increase amount of the developer replenishment amount based on the sum every time the predetermined number of sheets is counted,
During the operation of the developer carrying member, the second mode is set when the increase amount is less than a predetermined increase amount, and the third mode is set when the increase amount is equal to or greater than the predetermined increase amount. The image forming apparatus according to claim 5.   The image forming apparatus according to claim 1, wherein the control unit sets the third mode while the developer carrying member is stopped.

Images