JPH0930703A - Paper sheet discharging unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a paper sheet discharging unit capable of discharging paper sheets under an optimum condition without causing any inferior discharging trouble. SOLUTION: A CPU 9 takes in the rotating speed of an image forming device drive motor 16 and the transfer paper information, and during fixing process, a discharge drive motor 13 is rotated at the same speed as the image forming device drive motor 16, while, upon completion of the fixing process, the discharge drive motor 13 is rotated at high speed corresponding to the information from the transfer paper and the transfer paper is discharged on a discharge tray without any stacking trouble. When the time from feeding the transfer papers to a paper sheet discharge unit 1 to the time of discharging them, which is counted by a counter 18, exceeds a specific value, the discharge drive motor 13 is switched over to high rotating speed and the transfer papers are discharged under an optimum discharging condition with curls thereon removed, while, when a discharge paper sensor 3 detects that continuously discharged number of transfer papers have exceeded a specific value, the rotating speed of the discharge drive motor 13 is switched over to the high speed and stacking can be raised correspondingly to the number of transfer papers on the discharge paper tray.

Description

Detailed Description of the Invention

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[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper discharge unit incorporated in an image forming apparatus such as a copying machine or a printer for discharging transfer paper after fixing.

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine or a printer, a transfer sheet after passing through a fixing unit arranged at the final stage of an image forming operation is supplied to a sheet discharging unit as a post-processing apparatus to form an image. The transfer paper that has been subjected to the process is ejected to the paper ejection tray by the paper ejection unit. In this case, the paper discharge unit is driven by the drive motor that drives the fixing unit, and the transport roller of the paper discharge unit is
The transfer paper is conveyed at the same speed as the fixing unit.

The driving speed of the fixing unit is set so that the toner image is fixed on the transfer paper in an optimum state according to the quality of the transfer paper and the image forming conditions. Also,
Many image forming apparatuses in recent years have integrated a copying function, a facsimile function, and a printer function. In this type of apparatus, the pixel density required for image formation varies over a plurality of types, and the conveyance speed of the paper used is also high. Although there are a plurality of types, the transport rollers of the paper discharge unit arranged in the latter stage of the fixing unit placed at the final stage of each image forming operation discharge the transfer paper at the same speed as the fixing unit.

[0004]

In the conventional image forming apparatus, as described above, the paper carry-out unit is driven by the drive motor of the fixing unit arranged at the final stage of the image forming operation, and its drive speed is It is set according to the fixing characteristics of the fixing unit.

Therefore, in the paper discharge unit,
The discharge speed of the transfer paper transported to the discharge tray by the pair of transport rollers is not always optimal, and the discharge to the discharge tray is not smooth, paper is uneven in the discharge tray, or jams occur. Occasionally, a discharge failure accident such as occurrence occurred.

The present invention has been made in view of the current state of the above-described type of sheet discharge unit, and an object thereof is to discharge a sheet under optimum conditions without a discharge failure accident. To provide a paper discharge unit.

[0007]

In order to achieve the above object, the invention according to claim 1 is incorporated in an image forming apparatus which operates at plural kinds of transfer paper conveying speeds, and discharges the transfer paper after image formation. In the paper discharge unit, the transfer paper fixing process is performed based on the information about the rotational speed information of the drive motor of the image forming apparatus and the information about the transfer paper, and the information received by the information detection means. In the middle, the drive motor of the paper discharge unit is rotated at the same speed as the rotation speed of the drive motor of the image forming apparatus, and when the fixing process is completed, the drive motor of the paper discharge unit is driven to transfer the transfer paper. In accordance with the information, there is provided a first control means for rotating the image forming apparatus at a predetermined speed higher than that of the drive motor of the image forming apparatus.

Similarly, in order to achieve the above-mentioned object, the invention according to claim 2 is different from the invention according to claim 1 in that it measures the time from when the transfer paper is sent to the paper discharge unit until it is discharged. Means and the detection value of the time measuring means exceeds a predetermined value set in advance corresponding to the information taken in by the information detecting means, the rotational speed of the drive motor of the paper discharge unit is changed to the image forming apparatus. And a second control means for switching the rotation speed of the drive motor to a higher speed.

Similarly, in order to achieve the above object, the invention according to claim 3 is different from the invention according to claim 1 in that a sheet number detecting means for detecting the number of continuously discharged transfer sheets and a sheet number detecting means are provided. , If the number of detections exceeds the preset number of sheets,
Third control means for switching the rotation speed of the drive motor of the paper discharge unit to a high speed is provided.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the main part of this embodiment, and FIG. 2 is an explanatory diagram showing the configuration of an image forming apparatus incorporating this embodiment.

As shown in FIG. 2, an image forming apparatus incorporating this embodiment is provided with an image reading section 21 for reading a document image in the upper part of a housing 20, and is adjacent to the image reading section 21. A writing unit 22 that writes the original image read by the image reading unit 21 is provided in the housing 20 below, and the original image is exposed by the writing unit 22 at a substantially central position in the housing 20. A photoconductor 23 on which a latent image of the original image is formed is provided.

A developing unit 24 for developing a latent image of an original image formed on the photosensitive member 23 into a toner image is provided so as to closely face the peripheral surface of the photosensitive member 23, and the developing unit 24 is provided.
A transfer unit 25 for transferring the toner image formed on the photoconductor 23 onto the transfer paper is disposed adjacent to the photoconductor 23 in the clockwise direction. A fixing unit 17 that performs a fixing process is provided.
Near the exit of the fixing unit 17, a conveyance roller pair 28 that sends out the transfer paper that has been subjected to the fixing processing is disposed, and is adjacent to the conveyance roller pair 28 in the conveyance direction and detects the transfer paper that has undergone the fixing processing. A paper discharge sensor 6 is provided.

A transfer paper cassette 26 containing a transfer paper to be supplied to a transfer position is provided in the lower part of the housing 20, and a double-sided transfer unit for reversing the transfer paper which has been transferred on one side at the time of double-sided transfer and supplying it to the transfer position. 7 is provided, and a manual paper feed tray 27 is attached to one side of the housing 20.

The sheet discharge unit 1 according to this embodiment is provided on the other side of the housing 20 and is fed to the sheet discharge unit 1 at a position near the fixed sheet discharge sensor 6 of the image forming apparatus. A transfer paper detection sensor 2 for detecting the transfer paper is provided, and a paper discharge roller pair 4 for discharging the transfer paper is provided adjacent to the transfer paper detection sensor 2 in the transfer paper conveyance direction. On the side of 1, there is a pair of discharge rollers 4
A discharge tray 5 for accommodating the transfer sheets discharged by is attached, and a discharge detection sensor 3 for detecting the discharged transfer sheets is provided near the entrance of each discharge tray 5. .

As shown in FIG. 1, the paper discharge unit 1 is provided with a paper discharge unit control section 8 for controlling the paper discharge operation. The paper discharge unit control section 8 controls the entire operation. CPU 9, counter 1 for timing the paper discharge operation
8 and a RAM 10 to / from which various data are written / read during the paper discharge operation. A motor driver 19 for controlling the drive of the paper ejection drive motor 13 that drives the paper ejection roller pair 4, a paper ejection detection sensor 3, and a transfer paper detection sensor 2 are connected to the paper ejection unit controller 8.

On the other hand, as shown in FIG. 1, the image forming apparatus is provided with an image forming apparatus control section 14 for controlling an image forming operation. The image forming apparatus control section 14 has an image forming apparatus drive motor 16 provided therein. Driver 30 for driving and controlling
And the fixing paper ejection sensor 6 are connected. The paper discharge unit controller 8 and the image forming apparatus controller 14 are connected to each other by a signal line 31, and the CP of the paper discharge unit controller 8 is connected.
From the image forming apparatus control unit 14, U9 indicates the rotation speed information of the image forming apparatus drive motor 16, the transfer sheet size, the paper quality,
It is provided with three types of functions that take in information about the transfer path and other transfer paper and control the paper discharge unit control section 8 based on the taken information.

The first function is to convey the transfer sheet at the same speed as the driving speed of the fixing unit until the fixing processing of the transfer sheet is completed, and when the fixing processing of the transfer sheet is completed, information regarding the transfer sheet is displayed. It is a function of transporting and discharging the transfer paper at a predetermined speed correspondingly set in advance. The second function is a function of changing the transfer / discharge speed of the transfer paper in the paper discharge unit according to the time required from the sending of the transfer paper to the paper discharge unit to the discharge. The third function is a function of changing the transporting / discharging speed of the transfer paper of the paper discharge unit according to the amount of the transfer paper discharged to the paper discharge tray.

The operation of this embodiment having such a configuration will be described. The image forming control unit 14 of the image forming apparatus supplies a command signal to the motor driver 30 corresponding to the pixel density required for image formation, and the motor driver 30 causes the image forming apparatus drive motor 16 to correspond to the pixel density. And the image forming operation is performed.

The original image read by the image reading unit 21 is exposed on the photoconductor 23 by the writing unit 22, and an electrostatic latent image corresponding to the original image is formed on the photoconductor 23. This electrostatic latent image is formed. Are visualized as a toner image by the developing unit 24. In this way, the toner image formed on the photoconductor 23 is transferred by the transfer unit 25 to the transfer paper cassette 26, the manual paper feed tray 27 or the double-sided transfer unit 7.
It is transferred to the transfer paper supplied from.

The transfer paper on which the toner image is formed is
The transfer sheet is conveyed to the fixing unit 17, the transfer sheet is subjected to the fixing process, and the transfer sheet subjected to the fixing process is sent to the sheet discharging unit 1 by the conveying roller pair 28, and the sheet discharging roller pair 4 of the sheet discharging unit 1 is conveyed. Is discharged to the paper discharge tray 5. In this process, the fixing paper discharge sensor 6 detects the transfer paper that has been subjected to the fixing process and is sent to the paper discharge unit 1. The transfer paper detection sensor 2 causes the paper discharge unit 1 to discharge the transfer paper discharged by the paper discharge unit 1. The paper is detected, and the paper discharge sensor 3 detects the transfer paper discharged to the paper discharge tray 5.

FIG. 6 is a time chart of the paper discharge operation in the present embodiment. The fixing unit 17 is driven by the image forming apparatus drive motor 16 to form the image as shown in FIG. At the rotation speed corresponding to the pixel density required for
It is rotationally driven periodically. Then, when the fixing paper ejection sensor 6 detects the leading edge of the transfer paper as shown in FIG. 9A, the CPU 9 of the paper ejection unit control unit 8 issues a paper ejection instruction as shown in FIG. By the paper drive motor 13,
The paper discharge roller pair 4 starts rotating at the same standard rotation speed as the fixing unit 17. Further, when the fixing paper discharge sensor 6 detects the trailing edge of the transfer paper, the motor driver 19 causes the rotation speed of the paper discharge drive motor 13 to change in accordance with a command from the CPU 9.
The speed is switched to a predetermined speed higher than the rotation speed of the fixing unit 17, and the paper discharge roller pair 4 starts to rotate at this high speed.

FIG. 3 is an explanatory view showing the relationship between the paper information and the paper discharge speed, and the paper discharge unit 1 set at this time.
The linear velocity of the paper size, paper size and transfer paper supply path (paper feed stage)
Is set as shown in FIG. Here, in the paper feed stage 1, when the transfer paper is supplied from the transfer paper cassette 26, in the paper feed stage 2, when the transfer paper is supplied from the manual paper feed tray 27, the double-sided unit is configured to transfer the transfer paper to both sides. This is the case when it is supplied from the unit 7.

Thus, according to the present embodiment,
When the transfer paper passes through the fixing unit 17 and is sent to the paper discharge unit 1, the transfer paper is conveyed at a high speed and discharged, so that the discharged transfer paper is discharged onto the discharge tray without a stack defect, It is possible to increase the number of sheets and efficiently discharge the paper.

Further, according to the present embodiment, the time from the detection of the front end of the transfer paper by the transfer paper detection sensor 2 to the detection of the front end of the transfer paper by the paper ejection detection sensor 3 is timed,
When this time exceeds a preset reference value, the CPU 9 of the paper discharge unit control unit 8 determines that the curl of the transfer paper has increased and gives a command to the motor driver 19 to rotate the paper discharge drive motor 13. Is increased to rotate the paper discharge roller pair 4 at a high rotation speed to reduce the curl of the transfer paper.

This operation will be described with reference to FIGS. 4 and 7. FIG. 4 is an explanation of the paper discharge detection time after fixing corresponding to the paper information of this embodiment, and FIG. 7 is a flow chart showing the first paper discharge speed changing operation of this embodiment.

The copy operation is started in step S1 of the flow chart of FIG. 7, and the fixing paper discharge sensor 6 is started in step S2.
Detects the leading edge of the transfer paper, and in step S3, the motor driver 19 driven by a command from the CPU 9 of the paper discharge unit controller 8 causes the paper discharge drive motor 13 to have the same predetermined standard as the image forming apparatus drive motor. Start rotation at the rotation speed. Next, in step S4, when the transfer paper detection sensor 2 detects the leading edge of the transfer paper, the process proceeds to step S5, the counter 18 is cleared, and then the counter operation is started. In step S6, the paper discharge detection sensor 3
Detects the leading edge of the transfer paper.

Next, in step S7, it is determined whether the time required from the detection of the transfer sheet by the transfer sheet detection sensor 2 to the detection of the transfer sheet by the discharge detection sensor 3 exceeds a preset reference value. Is determined. This reference value is determined in correspondence with the paper size and the paper feed path information as shown in FIG. 4, and the RAM 10 of the paper discharge unit controller 8 corresponds to this paper size and the paper feed path information. The reference value is stored.

If it is determined in step S7 that the time required from the detection of the transfer paper by the transfer paper detection sensor 2 to the detection of the transfer paper by the paper discharge detection sensor 3 exceeds the preset reference value, In step S8, the motor driver 1 driven by a command from the CPU 9 of the paper discharge unit controller 8
9, the paper discharge drive motor 13 is rotated at a high speed, and the process proceeds to step S9 to rotate the paper discharge drive motor 13 at a high speed until the end of one job.

In step S7, it is assumed that the time required from the detection of the transfer paper by the transfer paper detection sensor 2 to the detection of the transfer paper by the paper discharge detection sensor 3 is within the preset reference value as shown in FIG. The process proceeds to step S10, and the paper discharge drive motor 13 continues to rotate at a predetermined standard rotation speed until the end of one job.

The time count of the counter 18 is larger than the reference value because the curl of the transfer paper is larger than usual.
This is a case where it takes more time than usual from the time when the leading edge of the transfer paper passes through the paper discharge roller pair 4 to the time when the paper reaches the paper discharge detection sensor 3 position. In this case, the pair of discharge rollers 4
If the rotation speed of the paper is set to be higher than the rotation speed of the fixing unit 17, the paper discharge roller pair 4 and the transfer paper slip, and the transfer paper becomes large while the transfer paper is sandwiched between the paper discharge roller pair 4 and the fixing unit 17. Receives tension and curls the transfer paper.

If the time count of the counter 18 is within the reference value, the paper discharge roller pair 4 of the paper discharge unit 1 will be described.
The rotation speed of is maintained at the same standard rotation speed as the rotation speed of the fixing unit 17, and the tension applied to the transfer paper sandwiched between the paper discharge roller pair 4 and the fixing unit 17 is reduced to discharge the paper. The transfer paper is conveyed by the roller pair 4 without rubbing and smearing.

As described above, according to the present embodiment, when the curl of the transfer paper increases, the rotational speed of the paper discharge roller pair 4 is made higher than the rotational speed of the fixing unit 17 to apply tension to the transfer paper. Since the curl of the transfer paper is reduced, the transfer paper can be discharged in an optimal discharge state.

Further, according to the present embodiment, when the transfer paper is accumulated on the discharge tray 5, the distance between the discharge port and the upper surface of the transfer paper is changed, and the stacking property is changed. When it is detected by the sensor 3 that a predetermined number of transfer sheets have been continuously discharged onto the discharge tray 5, the rotation speed of the discharge roller pair 4 of the paper discharge unit 1 is increased to stack the discharge trays. Is performed.

This operation will be described with reference to FIGS. FIG. 5 is an explanatory view of the conditions for changing the sheet discharge speed according to the present embodiment, and FIG. 8 is a flowchart showing the second sheet discharge speed changing operation according to the present embodiment.

Step S11 of the flowchart of FIG.
Then, the copy operation is started, the fixing paper ejection sensor 6 detects the leading edge of the transfer paper in step S12, the process proceeds to step S13, and the paper ejection drive motor 13 of the paper ejection unit 1 causes the paper ejection unit controller 8 to operate. In response to a command from the CPU 9, the fixing unit 17 starts to rotate at the same standard rotation speed as the rotation speed.

Next, in step S14, the counter 18 is cleared. In step S15, the transfer paper detection sensor 2 detects the leading edge of the transfer paper. In step S16, the paper discharge detection sensor 3 detects the transfer paper. Detect the tip. Then, the counter 18 counts the detection signals of the paper discharge detection sensor 3, the process proceeds to step S18, and it is determined whether or not the detection by the paper discharge detection sensor 3 is completed.

When it is determined in step S18 that the detection by the paper discharge detection sensor 3 is completed, the process proceeds to step S22 and the counter 18 is cleared. If it is determined in step S18 that the detection by the paper discharge detection sensor 3 is continuing, the process proceeds to step S19 and the counter 1
It is determined whether or not the count value of 8 exceeds the preset reference value 1. In step S19, the counter 1
When it is determined that the count value of 8 exceeds the preset reference value 1, it proceeds to step S20, and it is determined whether the count value of the counter 18 exceeds the preset reference value 2 or not, and step S20 If the determination is NO, the process proceeds to step S23, the paper ejection drive motor 13 that rotates the paper ejection roller pair 4 is driven at the clock frequency of 22 KHz, and if the determination in step S20 is YES, the process advances to step S21. Then, the paper ejection drive motor 13 that rotates the paper ejection roller pair 4 is driven at a clock frequency of 23 KHz. The relationship between the count value and the operation clock frequency shown in FIG. 5, which is the reference for the determination at this time, is stored in the RAM 10 in advance.

As described above, according to the present embodiment, when the transfer paper is ejected onto the paper ejection tray 5 in excess of a predetermined amount, the rotation speed of the paper ejection roller pair 4 corresponds to the ejection amount of the transfer paper. Is increased, depending on the stacking state of the transfer paper on the discharge tray 5,
Stackability is improved. When the transfer paper is removed by the operator during continuous paper feeding, the paper discharge detection counter 3 detects it, the counter 19 is cleared, the paper discharge speed is returned to the initial state, and the stackability of the transfer paper is maintained. It

In the present embodiment, as shown in FIG. 6, when the fixing paper discharge sensor 6 detects the trailing edge of the transfer paper, the rotation speed of the paper discharge drive motor 13 is switched to a high speed. However, if the rotation speed of the paper discharge drive motor 13 is switched to a high speed at a timing slightly earlier than the detection of the rear end of the transfer paper by the fixing paper discharge sensor 6, the high temperature transfer paper immediately after fixing is continuously pulled. Thus, it becomes possible to prevent the occurrence of curl.

[0040]

According to the first aspect of the present invention, the information detecting means takes in the rotational speed information of the drive motor of the image forming apparatus and the information about the transfer paper from the image forming apparatus, and the information is detected by the first control means. During the fixing processing of the transfer paper, the drive motor of the paper discharge unit is rotated at the same speed as the rotation speed of the drive motor of the image forming apparatus based on the information captured by the information detecting means, and the fixing processing is completed. Then, the drive motor of the paper discharge unit responds to the information on the transfer paper,
Since it is rotated at a predetermined speed, which is faster than the drive motor of the image forming apparatus, the discharged transfer paper is discharged onto the discharge tray without stacking defects, and the number of stacks can be increased to efficiently discharge the paper. Become. According to the invention of claim 2, in addition to the effect obtained by the invention of claim 1,
The time measuring means measures the time from the sending of the transfer paper to the paper discharging unit until the discharging, and the second control means makes the detection value of the time measuring means correspond to the information taken in by the information detecting means in advance. When the specified value is exceeded, the rotation speed of the drive motor of the paper discharge unit is switched to a higher speed than the rotation speed of the drive motor of the image forming apparatus. It is possible to discharge the transfer paper in this state. According to the third aspect of the invention, in addition to the effect obtained by the first aspect of the invention, when the number-of-sheets detecting means detects the number of continuously ejected transfer sheets exceeding the preset number, the third control is performed. Since the rotation speed of the drive motor of the paper discharge unit is switched to the high speed by the means, it becomes possible to enhance the stacking property according to the amount of transfer paper on the paper discharge tray.

[Brief description of drawings]

FIG. 1 is a block diagram illustrating a configuration of a main part of an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a configuration of an image forming apparatus incorporating the same embodiment.

FIG. 3 is an explanatory diagram showing a relationship between paper information and paper discharge speed according to the embodiment.

FIG. 4 is an explanatory diagram of a paper discharge detection time after fixing corresponding to the paper information of the embodiment.

FIG. 5 is an explanatory diagram of conditions for changing a sheet discharge speed according to the embodiment.

FIG. 6 is a time chart of the paper discharge operation of the same embodiment.

FIG. 7 is a flowchart showing a first paper discharge speed changing operation of the embodiment.

FIG. 8 is a flowchart showing a second sheet discharge speed changing operation of the same embodiment.

[Explanation of symbols]

 1 paper discharge unit 2 transfer paper detection sensor 3 paper discharge detection sensor 4 paper discharge roller pair 5 paper discharge tray 6 fixing paper discharge sensor 8 paper discharge unit control unit 9 CPU 10 RAM 18 counter

Claims (3)

[Claims] 1. A paper discharge unit that is incorporated in an image forming apparatus that operates at a plurality of transfer paper conveyance speeds and discharges transfer paper after image formation, comprising: rotational speed information of a drive motor of the image forming apparatus; On the basis of the information detecting means for taking in the information on the paper and the information taken in by the information detecting means, during the fixing processing of the transfer paper, the drive motor of the paper discharge unit is made to correspond to the drive motor of the image forming apparatus. When the fixing process is completed, the drive motor of the paper discharge unit is driven at a predetermined speed that is higher than the drive motor of the image forming apparatus according to the information of the transfer paper. And a first control unit for rotating the sheet discharge unit. 2. The paper discharging unit according to claim 1, wherein a time measuring means for measuring the time from the sending of the transfer paper to the paper discharging unit to the discharging, and a detection value of the time measuring means is used for detecting the information. When the predetermined value set in advance is exceeded in accordance with the information captured by the means, the rotation speed of the drive motor of the paper discharge unit is switched to a higher speed than the rotation speed of the drive motor of the image forming apparatus. And a control means for the sheet discharge unit. 3. The sheet discharging unit according to claim 1, wherein the number detecting means for detecting the number of continuously discharged transfer sheets, and the number detecting means for detecting a number exceeding a predetermined number set in advance, And a third control means for switching the rotation speed of the drive motor of the paper discharge unit to a high speed.