JP2015143774A - image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of efficiently decreasing the temperature of a process part.SOLUTION: The image forming apparatus includes a process cartridge 5 (process part) including a toner storage part, a fixing device 8 including a halogen lamp 83 and arranged at the approximately same height as the process cartridge 5, a housing 2 storing the process cartridge 5 and the fixing device 8, a duct 6 arranged between the process cartridge 5 and the fixing device 8 and extending in the width direction of a paper sheet, a fan 7 discharging air in the duct 6 to the outside of the housing 2, and a control part capable of executing a cooling mode for decreasing the temperature of the process cartridge 5. The duct can be switched between a first state and a second state where the inflow of the air from the side of the process cartridge 5 is easier than the first state by the movement of at least a part of the duct 6. The control part decreases the output of a heating element and brings the duct 6 into the second state, in the cooling mode.

Description

  The present invention relates to an image forming apparatus in which a fixing unit is disposed at substantially the same height as a process unit.

  2. Description of the Related Art Conventionally, in some image forming apparatuses, a process unit that forms a developer image on a recording sheet and a fixing unit that thermally fixes the developer image on the recording sheet are arranged at substantially the same height. . In such an image forming apparatus, when the temperature of the process section rises due to the heat of the fixing section, the developer in the process section melts and adheres, so when the temperature inside the machine rises, the temperature inside the machine is reduced. Need to lower.

  Therefore, for example, the image forming apparatus disclosed in Patent Document 1 includes a temperature sensor that detects the temperature around the process unit, and when the temperature detected by the temperature sensor reaches a predetermined temperature, the printing speed is decreased. At the same time, the inside of the machine is cooled by a fan.

JP 2001-117474 A

  By the way, in order to suppress the fixing of the developer in the process section, it is desired to lower the temperature of the process section more efficiently when the temperature inside the apparatus becomes high.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus that can efficiently lower the temperature of a process section.

In order to achieve the above-described object, the image forming apparatus of the present invention has a developer accommodating portion for accommodating a developer, a process portion for forming a developer image on a recording sheet, and a heating element, It is configured to thermally fix the developer on the recording sheet, and is disposed between the process unit and the fixing unit. A duct that is disposed and extends in the width direction of the recording sheet, a fan that exhausts air in the duct to the outside of the housing, and a control unit that can execute a cooling mode for lowering the temperature of the process unit are provided.
The duct can be switched between a first state and a second state in which air flows more easily from the process unit side than the first state by moving at least part of the duct.
And a control part makes a duct a 2nd state while reducing the output of a heat generating body in cooling mode.

  According to the image forming apparatus configured as described above, by executing the cooling mode, the air on the process unit side is easily exhausted by the fan, so that the temperature of the process unit can be efficiently lowered. In the cooling mode, since the output of the heating element is lowered, the fixing unit does not become excessively hot even if the air in the process unit is preferentially exhausted.

  In the above-described image forming apparatus, it is desirable that the control unit in the cooling mode lowers the recording sheet conveyance speed in the process unit and the fixing unit than when the cooling mode is not executed.

  According to this, even when the temperature of the fixing unit is lowered in the cooling mode, the developer image can be satisfactorily heat-fixed on the recording sheet.

  If the image forming apparatus includes a temperature sensor that detects the temperature in the housing, the control unit starts the cooling mode when the temperature detected by the temperature sensor exceeds a predetermined temperature. be able to.

  In addition, the image forming apparatus described above includes control means for determining whether or not the temperature in the housing is higher than a predetermined temperature using at least one of the number of printed sheets and the operating time of the heating element. The unit can start the cooling mode when the determination unit determines that the temperature in the housing is higher than the predetermined temperature.

  In the image forming apparatus described above, the duct is disposed between the process unit and the fixing unit, and the second wall is disposed on the fixing unit side with respect to the first wall and faces the first wall. And an intake port for taking in the air on the fixing unit side into the duct, and the second wall swings to switch from the first state to the second state. It is good also as a structure.

  In this case, the second wall may be swingable about the upper end.

  When the image forming apparatus includes a fixing frame that supports the heating element, the lower end of the second wall is fixed when the duct is in the second state than when the duct is in the first state. You may comprise so that it may become close to a flame | frame.

  Further, the second wall described above may be disposed at a position where the lower end is lower than the portion facing the second wall of the fixing frame.

  The swing center of the second wall described above may be disposed at a height position corresponding to the upper portion of the fixing frame.

  Moreover, the above-mentioned 2nd wall may be provided in the member which comprises a 1st wall so that rocking | fluctuation is possible.

  In the above-described image forming apparatus, the second wall may be engaged with the solenoid actuator, and the control unit may be configured to swing the second wall by controlling the solenoid actuator. .

  According to the present invention, by executing the cooling mode, the air on the process unit side is easily exhausted by the fan, so that the temperature of the process unit can be efficiently reduced. In the cooling mode, since the output of the heating element is lowered, the fixing unit does not become excessively hot even if the air in the process unit is preferentially exhausted.

1 is a cross-sectional view illustrating a schematic configuration of a laser printer according to an embodiment of the present invention. FIG. 3 is a cross-sectional view showing a duct, a process cartridge, and a fixing device when a normal printing mode is executed. It is a perspective view which shows a 1st wall and a 2nd wall, Comprising: The figure (a) which shows a 1st state, and the figure (b) which shows a 2nd state. It is sectional drawing which shows the duct at the time of cooling mode execution, a process cartridge, and a fixing device.

Next, an embodiment of the present invention will be described in detail with reference to the drawings as appropriate.
In the following, first, a schematic configuration of a laser printer 1 as an example of an image forming apparatus will be described, and then a characteristic part of the present invention will be described. In the following description, the direction will be described with reference to the user who uses the laser printer 1. Specifically, the right side of FIG. 1 that is the front side when viewed from the user is “front”, the left side of FIG. 1 that is the back side when viewed from the user is “rear”, and the front side of FIG. "The back side of the paper is" right ". Further, the vertical direction in FIG.

  As shown in FIG. 1, a laser printer 1 includes a paper feed unit 3 that supplies a sheet S as an example of a recording sheet in a housing 2, an exposure device 4, and a toner image (developer image) on the sheet S. ) And a fixing device 8 as an example of a fixing unit that thermally fixes the toner image on the paper S.

  The paper feed unit 3 is provided in the lower part of the housing 2, and includes a paper feed tray 31, a pressing plate 32, a paper feed roller 33, a separation roller 34, a separation pad 35, a conveyance roller 36, and a registration roller. 37 mainly. The paper S accommodated in the paper feed tray 31 is pushed up by the pressure plate 32 disposed in the paper feed tray 31 to be brought near the paper feed roller 33 and sent out toward the separation pad 35 by the paper feed roller 33. The fed paper S is separated one by one between the separation roller 34 and the separation pad 35, and is supplied to the process cartridge 5 by the conveyance roller 36 and the registration roller 37.

  The exposure device 4 is disposed in the upper part of the housing 2 and includes a laser light source (not shown), a polygon mirror, a lens, a reflecting mirror, and the like that are not shown. In the exposure device 4, the surface of the photosensitive drum 51 is exposed by scanning the surface of the photosensitive drum 51 at high speed with laser light (see the chain line) based on image data emitted from the laser light source.

  The process cartridge 5 is disposed below the exposure device 4 and is detachably mounted on the housing 2 through an opening formed when the front cover shown by omitting the reference numerals provided on the housing 2 is opened. It has become. The process cartridge 5 includes a photosensitive drum 51, a charger 52, a transfer roller 53, a developing roller 54, a supply roller 55, a layer thickness regulating blade 56, and a developer containing a toner (developer). And a toner storage unit 57 as an example of the unit.

  In the process cartridge 5, the surface of the photosensitive drum 51 is uniformly charged by the charger 52 and then exposed by high-speed scanning of the laser light from the exposure device 4, whereby image data is transferred onto the photosensitive drum 51. An electrostatic latent image based on is formed. The toner in the toner container 57 is supplied to the developing roller 54 via the supply roller 55 and enters between the developing roller 54 and the layer thickness regulating blade 56 to form a thin layer with a certain thickness on the developing roller 54. It is carried on.

  The toner carried on the developing roller 54 is supplied from the developing roller 54 to the electrostatic latent image formed on the photosensitive drum 51. As a result, the electrostatic latent image is visualized and a toner image is formed on the photosensitive drum 51. Thereafter, the sheet S supplied from the sheet feeding unit 3 is conveyed between the photosensitive drum 51 and the transfer roller 53, whereby the toner image on the photosensitive drum 51 is transferred onto the sheet S.

  The fixing device 8 is disposed behind the process cartridge 5 at substantially the same height as the process cartridge 5. That is, the fixing device 8 overlaps the process cartridge 5 when viewed from the front-rear direction.

  The fixing device 8 includes a heating roller 81 having a halogen lamp 83 as an example of a heating element therein, a pressure roller 82 disposed below the heating roller 81, a halogen lamp 83, the heating roller 81, and pressure. And a fixing frame 84 that supports the roller 82. The halogen lamp 83 is a heater that generates heat when energized. The pressure roller 82 is provided so as to form a fixing nip with the heating roller 81 by being pressed against the heating roller 81.

  In the fixing device 8, the heating roller 81 is heated by the halogen lamp 83, so that the toner image transferred onto the sheet S while the sheet S passes between the heating roller 81 and the pressure roller 82 is thermally fixed. Is done. Then, the sheet S on which the toner image is thermally fixed is discharged onto the discharge tray 22 by the transport rollers 23 and 24.

  In this laser printer 1, as shown in FIG. 2, the air around the process cartridge 5 and the fixing device 8 is blown by a fan 7 through a duct 6 provided between the process cartridge 5 and the fixing device 8. The air is exhausted out of the housing 2.

  Specifically, the duct 6 extends in the width direction of the paper S, that is, in the left-right direction. And the fan 7 is provided in the right side wall 21 of the housing | casing 2 in the right side of the duct 6, and is comprised so that the air in the duct 6 may be attracted | sucked and discharged | emitted out of the housing | casing 2. FIG.

  The duct 6 includes a first wall 110 disposed between the process cartridge 5 and the fixing device 8, a second wall 120 disposed on the fixing device 8 side, that is, the rear side with respect to the first wall 110, and a first wall 110. Mainly from the upper wall 25 of the housing 2 disposed on the first wall 110 and the second wall 120 and the extending wall 26 extending downward from a portion of the upper wall 25 located above the fixing device 8. It is configured.

  The duct 6 has a first intake port 61 that opens downward between the lower end of the first wall 110 and the lower end of the second wall 120 between the process cartridge 5 and the fixing device 8. Between the lower end of the wall 26 and the upper end of the second wall 120 is a second intake port 62 as an example of an intake port that opens to the fixing device 8 side above the duct 6. That is, the second intake port 62 is provided on the upper side of the second wall 120. By configuring the duct 6 in this way, when the fan 7 is operated, air on the process cartridge 5 side is taken into the duct 6 from the first intake port 61 and the fixing device from the first intake port 61. Eight-side air is taken into the duct 6.

  The second wall 120 is swingably provided on the wall member 101 that is a member constituting the first wall 110. Thereby, the duct 6 moves the second wall 120 so that the first state as shown in FIG. 2 and the distance between the first wall 110 and the second wall 120 than in the first state as shown in FIG. It is possible to switch to the second state in which the air easily flows into the duct 6 from the process cartridge 5 side.

  Specifically, the wall member 101 is a member that is supported by the housing 2, and, as shown in FIG. 3A, in addition to the first wall 110, rearward from the end portion in the left-right direction of the first wall 110. A right wall 130 and a left wall 140 extending to

  The first wall 110 is formed in a plate shape, and as shown in FIG. 2, extends from the lower side of the upper wall 25 of the housing 2 obliquely downward to the front, and the lower end is a photosensitive drum on the rear side of the process cartridge 5. 51 is disposed at substantially the same height as 51.

  Returning to FIG. 3A, the upper ends of the right wall 130 and the left wall 140 are provided at a substantially central portion in the vertical direction of the first wall 110. Each of the right wall 130 and the left wall 140 has a through hole (reference numeral omitted) penetrating in the left-right direction at the upper part of the rear end portion.

  The second wall 120 is a plate-like member having a width in the left-right direction that is substantially the same as the width in the left-right direction of the first wall 110. The second wall 120 has a shaft portion 121 that protrudes outward in the left-right direction from the upper part of both ends in the left-right direction. The second wall 120 can swing around the upper end with respect to the wall member 101 by passing the shaft portion 121 through the through holes of the right wall 130 and the left wall 140.

  The shaft 121 on the left side of the second wall 120 has a tip projecting outward in the left-right direction from the left wall 140, and a plate-like engagement portion 122 extending forward is provided at the projecting portion. . The engaging portion 122 has an opening 122A at the front end, and the slide pin 151 of the solenoid actuator 150 is engaged with the edge of the opening 122A.

  The solenoid actuator 150 has a slide pin 151 that can be moved up and down, and is controlled by a control unit 200 (see FIG. 2) provided in the housing 2 so that the slide pin 151 moves up and down and engages. This is a device that operates the portion 122 to swing the second wall 120.

  The solenoid actuator 150 is controlled by the control unit 200 to advance upward when the duct 6 is in the first state, and is retracted downward when the duct 6 is in the second state.

  Thereby, when the duct 6 is set to the first state, the engaging portion 122 is rotated upward, and the shaft portion 121 is rotated accordingly, and the lower end of the second wall 120 is closest to the first wall 110. The first posture is assumed. When the duct 6 is set to the second state, as shown in FIG. 3B, the engaging portion 122 is rotated downward, and the shaft portion 121 is rotated accordingly, so that the second wall 120 is The second posture is closer to the fixing frame 84 than when the lower end portion is farthest from the first wall 110 and is in the first posture.

Next, the positional relationship between the second wall 120 and the fixing frame 84 will be described.
As shown in FIG. 2, the fixing frame 84 includes a main body portion 84 </ b> A formed in a substantially U-shape that opens downward to cover the upper portion of the heating roller 81, and guide ribs 84 </ b> B extending forward from the main body portion 84 </ b> A. The first guide portion 84C is provided below the guide rib 84B.

  A plurality of guide ribs 84B are provided side by side in the left-right direction. Each guide rib 84B has an inclined surface that goes downward as the lower end surface goes rearward. In such a case, the lower end surface comes into contact with the leading edge of the paper S, and the paper S is guided between the heating roller 81 and the pressure roller 82.

  The first guide portion 84 </ b> C is formed so as to guide the paper S between the heating roller 81 and the pressure roller 82 by contacting the lower surface of the paper S carried out of the process cartridge 5.

  In the fixing frame 84 configured as described above, the front end portion of the guide rib 84B is positioned at the foremost side, that is, the process cartridge 5 side among the portions disposed above the fixing nip.

  The second wall 120 is disposed on the front side of the fixing frame 84 so as to face the tip of the guide rib 84B. The upper end of the second wall 120, which is the center of oscillation, is disposed at a position corresponding to the upper portion of the fixing frame 84 (more specifically, the upper portion of the main body portion 84 </ b> A), and the lower end is the guide rib 84 </ b> B of the fixing frame 84. It is arrange | positioned in the position lower than the front-end | tip.

  The control unit 200 includes a CPU, a RAM, a ROM, and the like (not shown), and the process cartridge 5 according to a detection result input from a temperature sensor 58 provided in the vicinity of the process cartridge 5 and a preset program. The cooling mode for lowering the temperature is configured to be executable.

  Here, the temperature sensor 58 is a sensor that detects the temperature in the housing 2. The temperature sensor 58 is provided on the side opposite to the process cartridge 5 with respect to the right side wall 21 of the casing 2, and detects the temperature in the vicinity of the process cartridge 5 in the casing 2.

  The control unit 200 executes the normal printing mode when the temperature detected by the temperature sensor 58 is equal to or lower than the predetermined temperature, and starts the cooling mode when the temperature detected by the temperature sensor 58 exceeds the predetermined temperature. It is configured as follows. The predetermined temperature can be appropriately set by experiments, simulations, or the like so that the temperature in the vicinity of the process cartridge 5 estimated from the temperature in the housing 2 does not exceed the melting temperature of the toner.

  Specifically, in the normal printing mode, the control unit 200 sets the output of the halogen lamp 83 to the first output, and sets the conveyance speed of the paper S in the process cartridge 5 and the fixing device 8 to the first speed. It is configured. And the control part 200 makes the state which the slide pin 151 of the solenoid actuator 150 advanced upwards, and makes the duct 6 the 1st state.

  In the cooling mode, the control unit 200 is configured to reduce the output of the halogen lamp 83 by setting the output of the halogen lamp 83 to a second output smaller than the first output. Further, the control unit 200 sets the transport speed of the paper S in the process cartridge 5 and the fixing device 8 to a second speed that is slower than the first speed. Then, the control unit 200 operates the solenoid actuator 150 so that the slide pin 151 is retracted downward, and the duct 6 is set in the second state.

The operation and effect of the laser printer 1 configured as described above will be described.
When a print job is input to the control unit 200, if the temperature detected by the temperature sensor 58 is equal to or lower than a predetermined temperature, the control unit 200 executes the normal print mode.

  In this normal printing mode, the duct 6 is in the first state, and the space between the first wall 110 and the second wall 120 is narrower than that in the second state. The air on the fixing device 8 side flows more than the air on the process cartridge 5 side. Thereby, the air heated by the fixing device 8 can be efficiently discharged out of the housing 2.

  When the temperature detected by the temperature sensor 58 exceeds a predetermined temperature due to continuous printing, the control unit 200 executes the cooling mode. In this cooling mode, as shown in FIG. 4, since the duct 6 is in the second state, the air on the process cartridge 5 side more easily flows into the duct 6 than when it is in the first state. As a result, the process cartridge 5 can be efficiently cooled, so that the toner accommodated in the process cartridge 5 can be prevented from being melted and fixed.

  Since the duct 6 is in the second state, the air on the fixing device 8 side is less likely to be taken into the duct 6 than when the duct 6 is in the first state. However, in the cooling mode, the output of the halogen lamp 83 is reduced. Therefore, it is possible to suppress an excessive increase in the temperature of the fixing device 8.

  In the cooling mode, since the conveyance speed of the paper S in the process cartridge 5 and the fixing device 8 is slowed down, the toner image can be fixed on the paper S satisfactorily even if the temperature of the fixing device 8 is lowered.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment. About a concrete structure, it can change suitably in the range which does not deviate from the meaning of this invention.

  In the embodiment, the control unit 200 is configured to start the cooling mode when the temperature detected by the temperature sensor 58 exceeds a predetermined temperature. However, the present invention is not limited to this. . For example, the laser printer 1 includes a determination unit that determines whether the temperature in the housing 2 is higher than a predetermined temperature based on the number of printed sheets, and the control unit 200 determines that the temperature in the housing 2 is the predetermined temperature. The cooling mode may be started when it is determined that the cooling mode is higher.

  For example, the determination unit determines that the temperature in the housing 2 is higher than a predetermined temperature when the number of printed sheets reaches 100. When the laser printer 1 is turned off, or when the halogen lamp 83 is turned off without a next print job being input for a certain time from the end of the previous printing, the determination means counts. The number of printed sheets is reset (set to zero), and the number of printed sheets is counted again.

  The determination means may be configured to determine whether the temperature in the housing 2 is higher than a predetermined temperature from the operation time of the halogen lamp 83, or the number of printed sheets and the operation time of the halogen lamp 83. It may be configured to determine whether or not the temperature in the housing 2 is higher than a predetermined temperature from both.

  When judging the temperature in the housing 2 from the operating time of the halogen lamp 83, for example, the judgment means turns on the halogen lamp 83 after turning on the laser printer 1 for a certain time. In addition, it is determined that the temperature in the housing 2 is higher than a predetermined temperature. If the halogen lamp 83 is turned off without a next print job being input within a certain time from the end of the previous printing, the judging means turns off the halogen lamp 83 after counting the operating time. It is configured to perform a subtraction process according to the set time.

  Further, for example, the control unit 200 may estimate the temperature in the vicinity of the process cartridge 5 from the temperature in the housing 2 detected by the temperature sensor 58 and determine whether the estimated temperature is higher than a predetermined temperature. . In this case, the predetermined temperature is set lower than the melting temperature of the toner.

  In the embodiment, the duct 6 can be switched between the first state and the second state by the swinging of the second wall 120, but the present invention is not limited to this. For example, the second wall may slide back and forth so that the duct can be switched between a first state and a second state in which air is more likely to flow from the process cartridge 5 side than the first state. .

DESCRIPTION OF SYMBOLS 1 Laser printer 2 Housing | casing 5 Process cartridge 6 Duct 7 Fan 8 Fixing apparatus 57 Toner accommodating part 58 Temperature sensor 83 Halogen lamp 84 Fixing frame 101 Wall member 110 1st wall 120 2nd wall 150 Solenoid actuator 200 Control part S Paper

Claims (11)

A process unit for forming a developer image on a recording sheet, having a developer storage unit for storing the developer;
A fixing unit having a heating element, configured to thermally fix the developer on the recording sheet, and disposed at substantially the same height as the process unit;
A housing for housing the process unit and the fixing unit;
A duct disposed between the process section and the fixing section and extending in the width direction of the recording sheet;
A fan for discharging the air in the duct out of the housing;
A control unit capable of executing a cooling mode for lowering the temperature of the process unit,
The duct can be switched between a first state and a second state in which air is more likely to flow in from the process unit side than the first state by moving at least part of the duct,
In the cooling mode, the control unit lowers the output of the heating element and places the duct in the second state.   2. The control unit according to claim 1, wherein, in the cooling mode, the control unit makes a recording sheet conveyance speed in the process unit and the fixing unit slower than when the cooling mode is not executed. Image forming apparatus. A temperature sensor for detecting the temperature in the housing;
The image forming apparatus according to claim 1, wherein the control unit starts the cooling mode when a temperature detected by the temperature sensor exceeds a predetermined temperature. Determining means for determining whether or not the temperature in the housing is higher than a predetermined temperature using at least one of the number of printed sheets and the operating time of the heating element;
3. The image formation according to claim 1, wherein the control unit starts the cooling mode when the determination unit determines that the temperature in the housing is higher than the predetermined temperature. 4. apparatus.   The duct is disposed between the process unit and the fixing unit, a first wall disposed on the fixing unit side with respect to the first wall, and a second wall facing the first wall; An inlet for taking in the air on the fixing unit side into the duct, and the second wall is swung to move the second from the first state. The image forming apparatus according to claim 1, wherein the image forming apparatus is switched to a state.   The image forming apparatus according to claim 5, wherein the second wall is swingable about an upper end portion. A fixing frame for supporting the heating element;
7. The duct according to claim 5, wherein when the duct is in the second state, a lower end portion of the second wall is closer to the fixing frame than when the duct is in the first state. Image forming apparatus.   The image forming apparatus according to claim 7, wherein the second wall is disposed at a position where a lower end is lower than a portion of the fixing frame facing the second wall.   9. The image forming apparatus according to claim 5, wherein the swing center of the second wall is disposed at a height position corresponding to an upper portion of the fixing frame. 10.   10. The image forming apparatus according to claim 5, wherein the second wall is swingably provided on a member constituting the first wall. 11. The second wall is engaged with a solenoid actuator;
The image forming apparatus according to claim 5, wherein the control unit swings the second wall by controlling the solenoid actuator.

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