JPH05216320A - Electrophotographic device - Google Patents

Abstract

PURPOSE:To prevent deterioration of image quality due to fixing failure when a waving is generated in a sheet by flow of air from a fan when recording. CONSTITUTION:A sensor before resist 35 detecting that a sheet S has reached a position immediately before the pair of resist rolls 21, is provided before the pair of resist rolls 21. A control means 36 is connected to the sensor before resist 35, the timing when the leading tip of the sheet S passes the transfer position P, is detected by the sensor before resist 35 and the driving of the fan 30 is stopped by the control means 36 for a specified time after detection until the leading tip of the sheet is inserted to a fixing position N. Thus, the flow of air from the fan 30 is prevented from hitting the sheet S which is ejected from a transferring device 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention records on a sheet by an electrophotographic system (a system for transferring an image formed on a photoconductor to a sheet for recording) such as a printer, a copying machine, and a facsimile using a laser. The present invention relates to an electrophotographic device.

[0002]

2. Description of the Related Art Conventionally, in an electrophotographic apparatus of this type, for example, a laser printer, an image on a photoconductor is transferred onto a sheet by a transfer device, and the transferred image on the sheet is fixed by a fixing device for recording. , The fan is driven to discharge the air in the main body of the apparatus to the outside, thereby suppressing the temperature rise in the main body of the apparatus and discharging ozone to the outside.

[0003]

However, in the prior art,
Since the fan is always driven, at the time of recording, the sheet exiting the transfer device is covered by the flow of air by the fan and is waving and conveyed to the fixing device. If the leading edge of the sheet enters the fixing device in this wavy state, the sheet is likely to have wrinkles, which may cause fixing failure and deteriorate image quality.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to prevent corrugation of a sheet due to air flow by a fan at the time of recording in the electrophotographic apparatus as described above, which causes defective fixing and deterioration of image quality. To do.

[0005]

Therefore, according to the first aspect of the present invention, the image on the photoconductor 11 is transferred to the sheet S as in the following examples shown in FIGS. 1 and 2,
While the transfer image on the sheet S is fixed, the fan 30
In the electrophotographic apparatus that discharges the air in the apparatus main body 10 by the above, a sensor such as a pre-registration sensor 35 that detects the transfer timing P passage timing of the leading edge of the sheet S, and at least the leading edge of the sheet S after the detection by the sensor. It is characterized by comprising a control means 36 for controlling the drive of the fan 30 until it enters the fixing position N.

According to a second aspect of the present invention, the fixing position N at the front end of the sheet S in the electrophotographic apparatus according to the first aspect is as shown in the following embodiments shown in FIGS. 3 and 4, for example.
A second device such as a paper ejection sensor 40 that detects the passage timing.
And the control means 36 returns the drive of the fan 30 to the normal state after the detection by the second sensor.

According to a third aspect of the present invention, as in the following embodiments shown in FIGS. 5 to 8, for example, in the electrophotographic apparatus of the first aspect, the shield plate 45 that can be opened and closed and the shield plate 45 thereof can be opened and closed. And the shielding plate 45 by controlling the driving means 50 for driving the driving means 50 and at least until the leading edge of the sheet S enters the fixing position N after the detection by the sensor.
And a control means 55 for preventing the flow of air by the fan 30 from reaching the sheet S.

According to a fourth aspect of the present invention, the fixing position N at the front end of the sheet S in the electrophotographic apparatus of the third aspect is as shown in the following embodiments shown in FIGS. 7 and 8, for example.
A second device such as a paper ejection sensor 40 that detects the passage timing.
And the control means 55 drives the shielding plate 60 to the open position after the detection by the second sensor.

[0009]

According to the first aspect, at the time of recording,
When the sensor detects the transfer position P passing timing of the front end of the sheet S, the control means 36 stops or weakens the driving of the fan 30 at least until the front end of the sheet S enters the fixing position N after the detection. Or control.

According to the second aspect of the present invention, when the second sensor detects the fixing position N passage timing, the post-detection control means 36 returns the drive of the fan 30 to the normal state.

According to the third aspect of the present invention, at the time of recording, when the sensor detects the transfer position P passing timing of the leading end of the sheet S, at least until the leading end of the sheet S enters the fixing position N after the detection. , Control means 55 to drive means 5
0 to drive the shielding plate 45 to the closed position, and the fan 3
Block the air flow due to 0 from reaching the sheet S.

According to the present invention, when the second sensor detects the passage timing of the fixing position N, the control means 55 after the detection drives the shield plate 60 to the open position.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 9 is a schematic view of the entire internal structure of a laser printer according to an embodiment of the present invention. Reference numeral 10 in the figure denotes the apparatus main body. A belt-shaped photosensitive body 11 is provided in the apparatus main body 10 substantially at the center. Around the photoconductor 11, a charging device 12, a developing device 13, a transfer device 14,
The cleaning device 15 is arranged. An optical writing device 16 is arranged above the charging device 12 and the cleaning device 15, and a paper feeding cassette 17 accommodating the sheet S is arranged below the transfer device 14.

The sheet S sent out from the sheet feeding cassette 17 by the sheet feeding roller 20 in the direction of arrow A in FIG. 9 is conveyed to the lower side of the photoconductor 11 by the registration roller pair 21 at a timing. The photoconductor 11 is driven in the clockwise direction shown by the arrow, and at that time, the surface thereof is uniformly charged by the charger 12, and the laser beam L from the optical writer 16 is applied to the photoconductor 11 to electrostatically charge the surface. Form an image. This latent image is visualized by toner when passing through the position of the developing device 13. Then, this visible image is transferred by the transfer device 14 onto the upper surface of the sheet S conveyed to the lower side of the photoconductor 11. Then, the sheet S after the image transfer is guided by the conveyance guide 22,
The transfer image is conveyed between the fixing rollers 23a and 23b of the fixing device 23 to fix the transferred image. Then, the sheet S exiting the fixing device 23
Is further conveyed by the paper discharge roller 24 and discharged in the direction of arrow B or C in FIG.

On the other hand, after the image transfer, the photoconductor 11 is cleaned by the cleaning device 15 to remove the residual toner, and then the static eliminator 2
Remove electricity at 5.

By the way, the laser printer described above, as shown in detail in FIG. 1, is driven to the lower right side of the transfer device 14 when the power of the apparatus main body 10 is turned on, and the air in the apparatus main body 10 is discharged to the outside. A fan 30 for discharging is arranged. An electric component section 31 is arranged on the left side of the fan 30. Further, the transport guide 22 is provided with a partition plate portion 22a formed by bending the front end of the transport guide 22 toward the fan 30.
Then, the partition plate portion 22a is branched into arrows a
Forming a flow path for air flowing in the b direction.

Further, a pre-registration sensor 35 is provided in front of the registration roller pair 21 in the sheet conveying direction (on the right side in FIG. 1).
To place. The pre-registration sensor 35 is turned on, for example, when the lever 35a falls down against the urging force of the sheet S fed from the sheet feeding cassette 17,
It is a sensor that detects that the sheet S has arrived just before the registration roller pair 21. Then, the pre-registration sensor 35 is connected to the control means 36, and the control means 36 is connected to the fan 30.

However, in the above laser printer,
The power of the apparatus main body 10 is turned on to drive the fan 30 to start blowing air. Then, as shown in FIG. 1, air flows in the a direction and the b direction are created in the apparatus main body 10. After that, when a print command is received and recording is performed on the sheet S, as shown in FIG. 2, when the pre-registration sensor 35 is turned on, the post-detection control means 36 turns off the fan 30 to stop driving. At the same time, the registration roller pair 21 is rotated in synchronization with the formation of the visible image on the photoconductor 11 to convey the sheet S, the visible image is transferred to the sheet S, and then the sheet S after transfer is fixed. It is conveyed to the container 23. At that time, the sheet S that has left the transfer position P is guided to the fixing position N along the transport guide 22 without waviness due to the flow of air. Then, the leading edge of the sheet S is fixed to the fixing roller 23a.2.
When the pre-registration sensor 35 is turned off after being bitten between 3b, the control means 36 turns on the fan 30 to restart the drive.

However, due to the flow of air in the a direction by the fan 30, the ozone generated in the transfer device 14 and the like around the photoconductor 11 is appropriately guided to the exhaust port and discharged to the outside, and the photoconductor 11 is formed by the ozone. Prevent deterioration of the. Further, due to the flow of air in the b direction, heat generated around the electrical equipment section 31 and the fixing device 23 in the fixing equipment 23 and the electrical equipment portion 31 is appropriately guided to the exhaust port and discharged to the outside. Suppresses temperature rise.

In the illustrated embodiment described above, the driving of the fan 30 is stopped and restarted based on turning on / off of the same pre-registration sensor 35. However, as in the following illustrated embodiment, for example, the fan 30 is driven. While the driving is stopped based on the pre-registration sensor 35, the driving can be restarted based on another second sensor.

In another embodiment, as shown in FIG. 3, for example, a pre-registration sensor 35 similar to that described above is provided in front of the registration roller pair 21, and the fixing rollers 23a and 23b are provided on the sheet ejection side ( A paper discharge sensor (second sensor) 40 is provided on the left side of the drawing. Paper ejection sensor 40
Is a sensor for detecting the leading edge of the sheet S immediately after passing through the fixing position N, which is turned on / off in accordance with the ups and downs of the lever, similarly to the pre-registration sensor 35. Then, the discharge sensor 40 is connected to the control means 36, and the control means 36 is similarly connected to the fan 30.

Now, in the other embodiment, at the time of recording, as shown in FIG.
5 is turned on, the fan 3 is detected by the control means 36 after the detection.
0 is turned off to stop driving. After that, when the paper discharge sensor 40 is turned on at the leading edge of the sheet S after image fixing, the post-detection control unit 36 turns on the fan 30 to restart driving.
Then, the flow of air by the fan 30 causes the apparatus body 1 to
Ozone in 0 is discharged and heat is released to suppress temperature rise.

In each of the above-described illustrated embodiments, the control means 36 controls the fan 30 to turn off when the pre-registration sensor 35 turns on. However, instead of turning off the fan 30 in such a manner, for example, when the pre-registration sensor 35 is turned on, the control means 36 weakens the drive of the fan 30 for a predetermined time, and controls so as to change from the normal blowing state to the breeze state. It can also be configured. Further, after that, when the paper discharge sensor 40 is turned on, the control unit 36 may be configured to control the drive of the fan 30 to return to the original normal air blowing state.

By the way, in the above embodiment, the driving of the fan 30 is stopped for a predetermined time after the pre-registration sensor 35 is turned on. However, as shown in the following illustrated embodiment, the power supply of the apparatus main body is turned on. After that, the fan may be continuously driven while the air flow by the fan may be regulated.

In this other embodiment, as shown in FIG. 5, for example, a shielding plate 45 is arranged on the right side of the transfer device 14 so as to be vertically movable. The shield plate 45 has a solenoid 46 at its lower end.
While hanging the tip of the operating arm 47 attached to
A spring 48 is hooked on the upper end and urged upward to reach the open position shown in the figure. Then, the solenoid 46 and the spring 48 constitute a driving means 50 for the shield plate 45.
The solenoid 46 is connected to the control means 55 connected to the pre-registration sensor 35.

At the time of recording, when the pre-registration sensor 35 is turned on, the solenoid 46 is turned on by the post-detection control means 55 and the shield plate 45 is lowered against the spring 48 as shown in FIG. The shielding plate 45 is set to the closed position. Then, the air flow path in the a direction by the fan 30 is blocked to prevent the air flow from reaching the sheet S. Therefore, the sheet S exiting the transfer position P is conveyed to the fixing position N without waviness due to the air flow. And
During that time, the fan 30 causes air to flow in the b direction, and the flow of air radiates heat. Then, when the pre-registration sensor 35 is turned off after the leading edge of the sheet S has entered the fixing position N, the control means 55 turns off the solenoid 46,
The shield plate 45 is returned to the original open position by the urging force of the spring 48. Then, the flow of air in the direction a by the fan 30 is restored to allow ozone to be discharged.

Further, in the embodiment shown in FIGS. 5 and 6, the shield plate 45 is opened and closed based on turning on / off of the same pre-registration sensor 35. The driving to the position may be performed based on another second sensor.

In this other embodiment, for example, as shown in FIG. 7, the tip end side of the partition plate portion 22a of the transport guide 22 is formed by a shield plate 60 which is rotatably attached with a support shaft 59 as a fulcrum. .. The shield plate 60 is the base end (the left end in the figure)
Then, the operation arm 47 attached to the solenoid 46 is locked, and the spring 48 is locked at the tip. Then, the shielding plate 60 is urged to rotate in the clockwise direction and properly stopped against the stopper so as to be in the open position in the drawing. Further, the pre-registration sensor 35 and the paper discharge sensor (second sensor) 40 similar to those described above are connected to the control means 55, and the control means 55 is connected to the solenoid 46.

In the other embodiment, during recording, as shown in FIG. 8, when the pre-registration sensor 35 is turned on, the solenoid 46 is turned on by the post-detection control means 55, and the shield plate 45 is spring 48. The shield plate 60 is rotated to the closed position. Then, the fan 30 blocks the air flow path in the a direction to prevent the air flow path from reaching the sheet S. After that, when the discharge sensor 40 is turned on at the leading edge of the sheet S after the image fixing, the control means 5 after the detection
At 5, the solenoid 46 is turned off and the shield plate 60 is returned to the original open position by the urging force of the spring 48. And fan 3
Restores the flow of air in the a direction by 0.

[0030]

Therefore, according to the first aspect of the invention, at the time of recording, when the sensor detects the transfer position passage timing of the leading edge of the sheet, at least until the leading edge of the sheet enters the fixing position. Since the control unit stops or weakens the drive of the fan, it is possible to prevent the sheet from being corrugated due to the air flow of the fan, which may result in poor fixing and deterioration of the image quality.

According to the second aspect of the present invention, when the second sensor detects the fixing position passage timing, the control means returns the drive of the fan to the normal state after the detection. Even if the entire driving stop time of the fan becomes long by recording on the sheet, the time should be shortened as much as possible to prevent the effect of ozone removal by the fan and the suppression effect of temperature rise from decreasing. You can also

According to the third aspect, at the time of recording,
When the sensor detects the transfer position passage timing of the leading edge of the sheet, at least until the leading edge of the sheet enters the fixing position, the shielding plate prevents the air flow from the fan from reaching the sheet. It is also possible to prevent the sheet from corrugating due to the flow of air by the fan without deteriorating the effect of removing or suppressing the temperature rise.

According to the fourth aspect of the present invention, when the second sensor detects the fixing position passage timing, the control means returns the shield plate to the open position after the detection, so that the sheet is continuously supplied without interruption. Even if the closing time of the shield plate is prolonged for a long time by recording in the above, it is possible to shorten the time as much as possible to prevent the effect of ozone removal by the fan and the suppression effect of temperature rise from decreasing. it can.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a main part of a laser printer according to an embodiment of the present invention.

FIG. 2 is a timing chart showing the operation of the control means of the laser printer.

FIG. 3 is a schematic configuration diagram of a main part of another embodiment in which driving of a fan is controlled by using two sensors in FIG.

FIG. 4 is a timing chart showing the operation of the control means in the embodiment.

FIG. 5 is a schematic configuration diagram of a main part of another embodiment in which a flow of air by a fan is restricted by a shield plate.

FIG. 6 is a timing chart showing the operation of the control means in the embodiment.

FIG. 7 is a schematic configuration diagram of a main part of another embodiment in which the driving of the shielding plate is controlled by using two sensors in FIG.

FIG. 8 is a timing chart showing the operation of the control means in the embodiment.

FIG. 9 is an overall schematic configuration diagram of a laser printer according to the present invention.

[Explanation of symbols]

 10 Device Main Body 11 Photoconductor 30 Fan 35 Pre-Registration Sensor (Sensor) 36/55 Control Unit 40 Paper Ejection Sensor (Second Sensor) 45/60 Shielding Plate 50 Driving Means N Fixing Position P Transfer Position S Sheet

Claims (4)

[Claims] 1. An electrophotographic apparatus in which an image on a photoconductor is transferred to a sheet and the transferred image on the sheet is fixed, while air in the apparatus main body is discharged by a fan, and a transfer position passage timing of a front end of the sheet. A sensor that detects
An electrophotographic apparatus comprising control means for controlling the drive of the fan at least until the leading edge of the sheet enters the fixing position after the detection by the sensor. 2. A second sensor for detecting a fixing position passage timing of a leading edge of a sheet is provided, and after the detection by the second sensor, the drive of the fan is returned to a normal state by the control means. The electrophotographic apparatus according to 1. 3. A shield plate which can be opened and closed, drive means for driving the shield plate, and the shield means by controlling the drive means at least until the leading edge of the sheet enters the fixing position after being detected by the sensor. 2. The electrophotographic apparatus according to claim 1, further comprising: a control unit that drives the sheet to a closed position to prevent the flow of air by the fan from reaching the sheet. 4. A second sensor is provided for detecting a fixing position passage timing of the leading edge of the sheet, and the control means drives the shielding plate to an open position after the second sensor detects the timing. Item 3. The electrophotographic apparatus according to Item 3.