JP2002229420A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cool the periphery of a fixing part so as to make temperature fall and to prevent adverse effect to respective parts on the periphery of the fixing part by actuating a cooling device for a fixed time even when a door member is opened because of paper jamming disposal or forcibly operating the cooling device at the prescribed time before an automatic shutoff function is actuated. SOLUTION: When the door member 130 is opened, a cutout switch 322 is turned off. According as the switch 322 is turned off, a 1st timer 200 starts counting, and also the cooling device 71 is actuated, and when time is up in the 1st timer 200, the device 71 is stopped. According as image forming operation is finished, a 2nd timer 201 starts counting. When the 2nd timer 201 attains 60 seconds before time is up, the cooling device is forcibly actuated, and when time is up in the 2nd timer 201, the device 71 is stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a facsimile, and a printer, and more particularly to an image forming apparatus using a heat fixing device.

[0002]

2. Description of the Related Art As an image forming apparatus such as a copying machine, a facsimile, a printer, etc., an apparatus employing a heat fixing system is widely known. A fixing device employing this method, that is, a heat fixing device, is mainly constituted by a heat roller provided with a heat source such as a halogen lamp inside a hollow roller, and a pressure roller in contact with the heat roller. Is passed through the nip formed by the heat roller and the pressure roller, so that the toner is fixed on the sheet. In such a heat fixing device, for example, when fixing toner on paper, for example, about 180 ° C. (fixing temperature)
Need to be high temperature. For this reason, the temperature around the fixing portion is considerably high.

Usually, a cooling device is provided as a cooling device for cooling the temperature around the fixing section.

The cooling fan is operated when the temperature is equal to or higher than the stable temperature (for example, 125 ° C.) of the fixing unit, and is not operated when the temperature is lower than the stable temperature.

On the other hand, a high-voltage power supply required for a charging unit and the like exists inside the image forming apparatus. In addition, a door member that can be opened and closed is provided on the front or side surface of the image forming apparatus for paper jam processing and maintenance. For example, when a paper jam occurs, the door member is opened and a hand is put inside the image forming apparatus to perform the paper jam processing. At this time, since it is very dangerous to touch the inside of the image forming apparatus in which the high-voltage power supply exists, from the viewpoint of safety, the high-voltage power supply is electrically connected in conjunction with opening and closing of the door member. One that is configured to cut off the energization of a high-voltage power supply line is widely commercialized. In these commercial products, the operation of the cooling device is stopped when the safety switch is turned off.

Further, there is an image forming apparatus equipped with an auto shut-off function for automatically shutting off a power supply when the apparatus has not been operated for a predetermined time from the viewpoint of energy saving. The image forming apparatus is provided with a timer, and when the image forming operation is completed, the timer starts counting. When any operation of the apparatus such as setting of a document or operation of an operation unit is performed for the next image forming operation while the timer is counting, the timer is reset. If any operation is not performed and the time is up (the timer count ends), the power is automatically shut off and the system enters the energy saving mode.
As described above, when the automatic shut-off function is activated and the apparatus enters the energy saving mode, the operation of the cooling device is also stopped.

[0007]

The above prior arts have the following problems. First, with respect to the prior art in which the high-voltage power supply line is cut off with the OFF of the safety switch, the OFF of the safety switch is often
Occurs when the door member is opened due to a paper jam or the like during the image forming operation. Therefore, immediately before that, the temperature of the fixing unit is a fixing temperature (180 ° C. in the case of the above-mentioned conventional technology)
Has been reached. However, when a paper jam occurs suddenly and the door member is opened for processing, the operation of the cooling device also stops. For this reason, the temperature around the fixing unit increases. Therefore, parts and the like near the fixing unit may be affected by the temperature rise. Depending on the material of the part, there is a possibility that the deformation of the shape, the life and the like may be affected.

[0008] Further, as the size of the apparatus is reduced as in the case of a small machine, each component is densely arranged. For example, an apparatus in which toner such as a cleaning unit and a developing unit is stored near a fixing unit. When the image forming apparatus is used in a high-temperature environment, the toner is agglomerated and the fluidity is impaired due to a rise in the temperature around the fixing unit due to the stop of the operation of the cooling device. Cause a phenomenon. When this blocking phenomenon occurs, the residual toner is not conveyed downstream from the blocking unit in the cleaning unit, so that new residual toner overflows from the cleaning unit. Further, in the developing section, there is a possibility that a problem that the toner is not stirred or transported and affects the image may occur.

Also, in the prior art having an auto shut-off function, the fixing unit is operated at a fixing temperature (in the case of the above prior art) so that the image forming operation can be started immediately before the timer expires. 180 ° C). With the expiration of the timer, the operation of the cooling device stops. Therefore, the same problem as described above may occur.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, and to operate a cooling device for a fixed time even if a door member is opened due to a paper jam or the like, or to provide an automatic shut-off function. By operating the cooling device strongly for a certain period of time before the operation of the fixing unit, the temperature around the fixing unit is cooled, so that the components around the fixing unit are not affected.

[0011]

According to the first aspect of the present invention, there is provided a fixing unit for heating and fixing a toner image transferred onto a sheet of paper.
A cooling device for cooling the temperature around the fixing unit raised by the fixing unit, and a safety switch that is turned off in conjunction with the opening operation of the door member that can be opened and closed. An image forming apparatus configured to cut off the energization of a high-voltage power supply line in the apparatus includes a first timer that starts counting when the safety switch is turned off, and is provided between the start and end of the count of the first timer. An image forming apparatus characterized by cooling a temperature around a fixing unit by operating a cooling device.

According to the present invention, the safety switch is turned off.
Even if the cooling device is operated for a predetermined time, the temperature around the fixing unit can be cooled. Therefore, a rise in temperature around the fixing unit can be suppressed, so that it is possible to prevent adverse effects of the components disposed around the fixing unit.

According to a second aspect of the present invention, there is provided a fixing unit for heating and fixing a toner image transferred onto a sheet, and a cooling device for cooling the temperature around the fixing unit raised by the fixing unit. A second timer that starts counting when the image forming operation ends, and an image forming apparatus that has an auto shut-off function that automatically shuts off power when the counting of the second timer ends. The cooling device can be operated in at least two stages of a weak operation and a strong operation in which the cooling power is stronger than the weak operation, and the cooling device is operated for a predetermined time before the end of the count of the second timer until the end of the count. The image forming apparatus is characterized in that the temperature around the fixing unit is cooled by strong operation.

According to the present invention, the cooling device operates strongly from a predetermined time before the automatic shut-off function is activated, so that the temperature around the fixing unit can be cooled. Therefore, a rise in temperature around the fixing unit can be suppressed, so that it is possible to prevent adverse effects of the components disposed around the fixing unit.

According to a third aspect of the present invention, in the image forming apparatus, the cleaning unit or the developing unit is disposed near the fixing unit. Device.

According to the present invention, even in an image forming apparatus in which a cleaning unit and a developing unit are arranged near the fixing unit, blocking of toner in the cleaning unit or the developing unit due to a rise in temperature around the fixing unit is prevented. can do.

[0017]

FIG. 1 is an external perspective view of an image forming apparatus according to one embodiment of the present invention, and FIG. 2 is a schematic diagram showing the internal structure of the image forming apparatus according to one embodiment of the present invention. Referring to FIG. 1, an image forming apparatus main body 10 is covered in appearance by a main body housing 11, and includes a reading unit 12, a discharging unit 45, and a writing unit 13 in this order from above.

Referring also to FIG. 2, the reading unit 12 includes a document table 20 for placing a document and the document table 2.
The automatic document feeder 21 includes an automatic document feeder 21 mounted on the document table and a reading optical unit 22 for reading an image of the document placed on the document table.

The discharge portion 45 is located below the reading optical portion 22. Referring to FIG. 1, the discharge portion 45 has a substantially U-shaped cross-section which enters into the substantially vertical middle portion of the main body housing 11 in the vertical direction. And a discharge unit 45 for discharging the sheet on which the image is formed by the writing unit 13 into the space.
Is configured.

A writing section 13 is formed on the left side and the lower side (the direction is described in FIG. 2) of the discharge section, and the writing section 13 is formed by a sheet feeding section 30, an image forming section 31, and a discharge roller 44. It is mainly composed. The paper P is deposited on the paper supply unit 30, and the paper is supplied to the image forming unit 31 by the paper supply roller 301. The image forming unit 31 is located on the downstream side of the sheet feeding unit 30 in the transport direction of the sheet P, and includes a photosensitive drum 310 and the photosensitive drum 310.
Charging unit 311 and writing optical unit 32 disposed around
, Developing unit 312, transfer unit 313, and cleaning unit 314
And a fixing unit 315 disposed downstream of the photosensitive drum 310 in the transport direction of the sheet P.
The discharge roller 44 is located downstream of the fixing unit 315 in the sheet P transport direction. The fixing unit 315 has a halogen heater and a heat source 50 inside the hollow fixing roller 51, and the pressure roller 52 is in contact with the fixing roller 51. The temperature control of the fixing unit will be described later.

FIG. 3 is a schematic cross-sectional view of an image forming apparatus according to an embodiment of the present invention. Referring to FIGS. 2 and 3, a louver 67 leading to a cooling fan 70 is provided on the back side of the discharge unit 45 (see FIG. 3 for the direction). A louver 64 is also provided below the discharge roller 44 on the left side of the discharge unit 45, and further, a fixing unit 315 is provided.
A louver 73 is also provided on the left side of. When the cooling fan 70 is rotated by a driving source (not shown), a flow of wind is generated as shown by an arrow in FIG. 3 so that the temperature of the fixing unit 315 and the temperature around the fixing unit can be cooled.

FIG. 4 is a block diagram showing an embodiment of the present invention. Referring to FIG. 4, high-voltage substrate 321 for controlling voltage application to charging unit 311 and fixing unit 3
15 and the safety switch 322 are electrically connected to each other and constitute a high-voltage power supply line 320. The high-voltage power supply line 320 is connected to the O of the safety switch 322.
N, the connection state is established and the safety switch 322 is turned off.
It is configured to be disconnected by F. The fixing unit 315, the high-voltage board 321 and the safety switch 322 constituting the high-voltage power supply line 320 are connected to the CPU 500 as control means, and are individually controlled. In the present invention, the fixing section may not be connected to the high-voltage power supply line, and the high-voltage power supply line may be constituted only by the high-voltage board and the safety switch, or another electric component may be connected.

The ON / OFF configuration of the safety switch 322 will be described with reference to FIG. FIG. 5 is a diagram showing a simplified internal structure in one embodiment of the present invention. FIG.
, A door member 130 that is rotatable in the direction of arrow A is provided on the front side of the writing unit 13 of the main body housing 11 (see FIG. 5 for the direction). The door member 130 is provided with a projection 131. On the other hand, a safety switch 322 is provided in the main body housing 11 at a position corresponding to the protrusion 131, and the door member 130
Is closed with respect to the main body housing 11 (the state shown by the solid line in FIG. 5), the safety switch 322 is turned ON, and the above-mentioned high-voltage power supply line is energized. When the door member 130 is rotated in the direction of arrow A and opened with respect to the main body housing 11 (the state shown by the broken line in FIG. 5), the safety switch 322 is turned off, and the high-voltage power supply line 320 is not electrically connected. It is designed to be shut off. The opening and closing of the door member 130 is usually performed at the time of paper jam processing and maintenance.

Referring again to FIG. 4, fixing unit 315
The temperature of the fixing unit 315 is controlled by the CPU 500. The fixing unit 315 has a built-in temperature measuring device 53 such as a thermistor so that the temperature of the fixing unit 315 can be measured. The temperature measured by the temperature measuring device 53 is sent to the CPU 500,
The heat source 50 is turned on so that the fixing unit 315 is maintained at a predetermined temperature.
NOFF control is performed by the CPU 500. In this embodiment, the temperature at which the toner image is properly fixed on the sheet onto which the toner image has been transferred, that is, the fixing temperature is set to 180 ° C., and the control is usually performed so that the fixing unit 315 is maintained at 180 ° C.

A cooling device 71 composed of a cooling fan 70 and a drive source (not shown) is connected to the CPU 500. The cooling fan 70 is controlled by the CPU 500 to
The drive source is driven to rotate the cooling fan 70 only when the value measured by the 15 temperature measuring devices 53 is 125 ° C. or higher. Further, the operation of the cooling device in the present embodiment can be switched between two stages. Specifically, the cooling fan 70 can be rotated in two stages: a strong operation of rotating the drive source of the cooling fan 70 at full speed, and a weak operation of rotating at a rotational speed lower than the full speed. The switching between the strong operation and the weak operation is performed by switching the current value sent to the drive source. These instructions are also performed by the CPU 500.

In addition, the power supply 1, the first timer 200 and the second timer 201 are also connected to the CPU 500.
The first timer 200 starts counting when the safety switch 322 is turned off, and times out (ends counting) after 60 seconds. The second timer 201 starts counting with the end of the image forming operation, and times out (ends counting) after 600 seconds. Second timer 2
01 is used for a so-called auto-shut-off function in which the power is automatically turned off when no operation is performed on the image forming apparatus 10 within a predetermined time after the end of the image forming operation.

Next, the operation of the embodiment of the present invention will be described with reference to a flowchart and a timing chart. FIG. 6 is a flowchart in the case where the cooling device operates in accordance with the turning off of the safety switch, and FIG. 7 is a flowchart in the case where the cooling device operates before a predetermined time before the automatic shut-off function operates. FIG. 8 is a timing chart in a case where the cooling device operates in accordance with the turning off of the safety switch, and FIG. 9 is a timing chart in a case where the cooling device operates before a predetermined time before the automatic shut-off function operates.

Referring to FIG. 6 and FIG.
A case in which the cooling device operates with the FF will be described. First, the first timer 200 is reset (step 1), and when the safety switch 322 is ON, the cooling device is under normal control (step 2). The normal control of the cooling device is, as described above, a control in which the cooling device is activated when the temperature measured by the temperature measuring device 53 of the fixing unit 315 is equal to or higher than 120 ° C., and is not activated when the temperature is lower than 120 ° C. is there. The operation state is an operation in a weak operation slower than the strong operation, but in this case, the operation may be a strong operation. Here, for example, during image formation, the writing unit 1
3, when the paper P is jammed, the door member 13
When 0 is opened and the safety switch 322 is turned off (step 3), the count of the first timer 200 is started (step 4), and the cooling device 71 is activated (step 5). If the safety switch 322 is turned off in step 3, the process returns to step 1. First timer 20
If the safety switch 322 is kept OFF until the time reaches zero, the first timer 200 times out (step 7) and the cooling device stops (step 8).
When the door member 130 is closed and the safety switch 322 is turned on before the time of the first timer 200 expires, the process returns to step 1 and the first timer 200 is reset. In the present embodiment, the time-up setting of the first timer 200 is set to 60 seconds. However, the present invention is not limited to this value, and it is possible to select an optimum value according to various conditions of the image forming apparatus. It is possible.
As described above, since the cooling device is operated for a certain period of time when the safety switch is turned off, the temperature around the fixing unit does not increase with the safety switch being turned off.

Next, referring to FIGS. 7 and 9, the second timer 201 is reset (step 10), and the cooling device is normally controlled (step 11). The normal control of the cooling device is, as described above, a control in which the cooling device is activated when the temperature measured by the temperature measuring device 53 of the fixing unit 315 is equal to or higher than 120 ° C., and is not activated when the temperature is lower than 120 ° C. is there. The operation state is an operation in a weak operation that is slower than the strong operation. Thereafter, the second timer 201 starts counting with the end of the image forming operation (step 12). If the image forming operation has not been completed, the process returns to step S11. If no operation is performed on the image forming apparatus 10 from the start of the count of the second timer 201 to 60 seconds before the time-up of the second timer 201 (step 14), the time-up of the second timer 201 60s
Before ec (step 15), the cooling device is activated strongly (step 16). If any operation is performed on the image forming apparatus 10 from the start of counting by the second timer 201 to 60 seconds before the time-up of the second timer 201, the process returns to step S11. If the time has not reached 60 seconds before the time-up of the second timer 201, the process returns to step 14. If strong operation of the cooling device is started and no operation is performed on the image forming apparatus 10 before the time-out of the second timer 201 (step 17), the second timer 201 times out (step 18), and Accordingly, the automatic shut-off function operates (step 19). When the auto shut-off function is activated, the power supply is cut off and the operation of the cooling device is stopped. In this embodiment, the strong operation of the cooling device is started for 60 seconds of the operation of the auto shut-off function.
c, although the present invention is not limited to this numerical value, it is possible to select an optimal numerical value according to various conditions of the image forming apparatus. As described above, the cooling device is operated more strongly than usual for a certain period of time before the auto shut-off function is activated, so that the temperature around the fixing unit increases with the activation of the auto shut-off function. Absent.

In the above embodiment, the strong operation of the cooling device and the operation of the automatic shut-off function are performed by one second timer. However, the timer for the strong operation of the cooling device and the timer for the automatic shut-off function are operated. They may be provided separately.

As shown in FIG. 2, a second cooling device 60 is provided in addition to the cooling device 71. In the case of strong operation, both the cooling device 71 and the second cooling device 60 are operated, and in the case of weak operation, Alternatively, any one of the cooling devices may be operated.

In order to more effectively cool the temperature around the fixing unit, in addition to the above-described embodiment, that is, when the safety switch is turned off or a predetermined time before the automatic shut-off function, the fixing unit is turned off. The temperature control may be slightly lower than usual. For example, if the normal fixing control temperature is 180 ° C., the safety switch OF
The control temperature of the fixing may be changed to 175 ° C. with F or a predetermined time before the automatic shut-off function.

According to the present invention, in an image forming apparatus in which a discharge section having a substantially U-shaped cross section is provided at a substantially middle portion in a vertical direction of a main body housing as shown in FIG. 2, each element of the image forming section is dense. In particular, when a cleaning device is arranged near the fixing unit, or when a developing unit (not shown) is arranged near the fixing unit, blocking of toner in the cleaning unit and the developing unit is prevented. It is particularly effective because it can be done.

As described above, according to the present invention, even when the safety switch is turned off, the cooling device operates for a predetermined time, so that the temperature around the fixing unit can be cooled.
Therefore, a rise in temperature around the fixing unit can be suppressed, so that it is possible to prevent adverse effects of the components disposed around the fixing unit.

Further, since the cooling device operates strongly for a predetermined time before the automatic shut-off function operates, the temperature around the fixing unit can be cooled. Therefore, a rise in temperature around the fixing unit can be suppressed, so that it is possible to prevent adverse effects of the components disposed around the fixing unit.

Further, even in an image forming apparatus in which a cleaning unit and a developing unit are arranged in the vicinity of the fixing unit, blocking of toner in the cleaning unit or the developing unit due to a rise in temperature around the fixing unit can be prevented. .

[0037]

[Brief description of the drawings]

FIG. 1 is an external perspective view of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing an internal structure of the image forming apparatus according to one embodiment of the present invention.

FIG. 3 is a schematic cross-sectional view of the image forming apparatus according to one embodiment of the present invention.

FIG. 4 is a block diagram showing one embodiment of the present invention.

FIG. 5 is a diagram showing a simplified internal structure in one embodiment of the present invention.

FIG. 6 is a flowchart in the case where the cooling device operates in response to the OFF of the safety switch.

FIG. 7 is a flowchart in the case where the cooling device operates before a predetermined time before the automatic shut-off function operates.

FIG. 8 is a timing chart in a case where the cooling device operates in response to turning off of the safety switch.

FIG. 9 is a timing chart in a case where the cooling device operates before a predetermined time before the automatic shut-off function operates.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 image forming apparatus main body 11 main body housing 71 cooling device 200 first timer 201 second timer 315 fixing unit 320 high-voltage power supply line 500 CPU

Continuing on the front page (72) Inventor Tomohide Hozono, 1-2-28 Tamazo, Chuo-ku, Osaka City Inside Kyocera Mita Co., Ltd. (72) Inventor Kenichi Tanabe 1-2-28 Tamazo, Chuo-ku, Osaka City Kyocera Mita (72) Inventor Hiroshi Kinoshita 1-2-28 Tamazo, Chuo-ku, Osaka-shi F-term in Kyocera Mita Corporation (reference) 2H027 DA26 DA31 DA38 EK06 EK09 JA11 JB17 JB24 JC08 ZA04 2H033 AA24 AA41 BA06 BA29 CA34 CA53 2H034 CA04 2H071 AA17 AA42 BA14 BA17 BA20 DA08 DA12 DA13 DA32 DA34 EA16

Claims (3)

[Claims] A fixing unit for heating and fixing the toner image transferred onto the sheet; a cooling device for cooling the temperature around the fixing unit raised by the fixing unit; An image forming apparatus having a safety switch which is turned off in conjunction with the operation, and in which the energization of a high voltage power supply line in the apparatus is cut off when the safety switch is turned off. An image forming apparatus comprising: a first timer for starting counting by a timer; and operating a cooling device to cool the temperature around the fixing unit from the start to the end of counting of the first timer. 2. A fixing unit for heating and fixing a toner image transferred onto a sheet, a cooling device for cooling the temperature around the fixing unit raised by the fixing unit, and the end of the image forming operation. A second timer that starts counting by a timer, and an auto-shut-off function that automatically shuts off power when the counting of the second timer ends. The operation can be performed in at least two stages of strong operation in which the cooling power is stronger than the operation, and the cooling device is strongly operated from a predetermined time before the end of the count of the second timer to the end of the count to make the surroundings of the fixing unit peripheral. An image forming apparatus for cooling a temperature. 3. The image forming apparatus according to claim 1, wherein the image forming apparatus has a toner storage unit adjacent to the fixing unit.