JPH06138736A - Paper guiding device to photosensitive drum in image forming device - Google Patents

Abstract

PURPOSE:To excellently carry out the transfer of an image by controlling the size of a loop formed by paper fed from a paper carrying path at a position where a toner image formed on a photosensitive drum is transferred to paper according to the stiffness of the paper. CONSTITUTION:The stiffness of the paper is measured by arranging a sensor 15 for measuring the pressurizing force of the loop Pr of the paper to a paper fitting device 10 arranged uptream of an image transfer part from the photosensitive drum 1 and matched by forming a loop on the paper. Furthermore, a driving device 7 for rocking an upper guide plate 5 is arranged between a resist roller device 11 and a photosensitive drum and the size of the loop Ps is controlled by rocking the upper guide plate according to the information outputted from a controller 20 according to the information of the strength of the paper. Then, turbulence in the image is prevented without rubbing the drum surface by the force of the loop by allowing the position of the paper at an image transfer part to be controlled.

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 an electrophotographic copying machine for guiding a sheet sent from a sheet aligning device toward an image transfer section from a photosensitive drum, and more particularly to a sheet. The strength of the paper pressing the photoconductor drum when the paper is guided to the photoconductor drum is controlled according to the waist strength information of the paper, and the paper is fed while preventing the toner image from rubbing. The present invention relates to a paper guide device for a photosensitive drum in an image forming apparatus for paper.

[0002]

2. Description of the Related Art In an image forming apparatus such as an electrophotographic copying machine for producing recording paper by using an electrophotographic method,
Transfer the toner image created on the photoconductor drum to paper,
The paper carrying the toner image is fixed through a fixing device and discharged as recording paper. In the image forming apparatus, in order to feed the paper to the image transfer portion from the photoconductor drum, a paper feed path for connecting the paper feed portion where the paper feed tray is arranged and the image transfer portion of the photoconductor drum is connected. In addition, a large number of roller devices are provided to configure a sheet conveying device, and a mechanism for feeding the sheet is provided. In the paper conveying path, a paper aligning device in which a registration roller device and a pre-registration roller device are arranged at a predetermined interval in front of the image transfer portion from the photosensitive drum is provided.

In the paper aligning device, the leading end of the paper is projected into the registration roller device,
The pre-registration roller device performs an additional feeding operation to form a loop on the paper, and the reaction force of the loop uniformly presses the leading end of the paper against the registration roller device to perform the paper alignment operation. . Therefore, even if a state in which the roller device does not give a uniform feeding action in the width direction to the sheet transported in the sheet transport path by performing the aligning action on the sheet in the sheet aligning device, The sheet which is released from the oblique feeding state and is sent out to the image transfer portion through the registration roller device is conveyed in a normal posture to transfer the toner image.

Further, a guide plate member for guiding the paper toward the photoconductor drum is arranged between the paper aligning device and the image transfer portion of the photoconductor drum, and the leading end of the paper is set on the photoconductor drum. The contact angle is set so that the paper does not rub the surface of the photoconductor drum. For example, in the example disclosed in Japanese Utility Model Laid-Open No. 2-15947, a film member for pressing the paper is arranged at the tip of the paper guide path from the paper aligning device to the photosensitive drum.
A mechanism is provided to adjust the angle at which the paper enters the photosensitive drum. The leading edge of the paper is pressed and guided in the direction of rotation of the photoconductor drum to control the angle at which the paper contacts the photoconductor drum, preventing the paper from rubbing the surface of the photoconductor drum. Then, the function of transferring the toner image to the sheet can be performed in a good state.

[0005]

However, as shown in the above-mentioned conventional example, even when adjusting the plunge angle at which the paper contacts the photosensitive drum, if the stiffness of the paper is different, the paper Since the force pressing the surface of the photosensitive drum changes depending on the strength of the waist, the image transfer function may not be performed well. Therefore, for example, the actual exploitation Sho 62-1819
As disclosed in Japanese Patent No. 53, etc., a means for measuring the waist strength of a paper is arranged in a paper feed section from a paper feed tray, and information about the waist strength of the paper is used to detect a portion immediately before the photosensitive drum. It has been proposed to use a mechanism capable of controlling the angle at which the guide plate disposed at the position is rocked and adjusting the angle at which the paper contacts the photosensitive drum.

In addition to the above-mentioned conventional example, in order to control the plunging angle of the paper into the photosensitive drum, for example, it can be constructed as shown in Japanese Utility Model Laid-Open No. 58-69848. The apparatus of the conventional example is configured as shown in FIG. 4, and a transfer corotron 2 is arranged corresponding to the photosensitive drum 1, and a position for transferring a toner image from the photosensitive drum onto a sheet. The upper guide plate 5 and the lower guide plate 8 are arranged to face each other in order to guide the sheet fed by the registration roller device 11 toward the.
Then, the lower guide plate 8 is supported via the support shaft 8a,
When the top portion of the loop of the sheet is regulated by the upper guide plate 5 when the sheet P is urged upward by the spring 9 toward the photosensitive drum by the registration roller device 11, the sheet P is regulated. Depending on the strength of the waist, the lower guide plate 8 is pushed down. Therefore, when the lower guide plate 8 is swung in accordance with the stiffness of the paper, the angle θ of the loop in which the paper is pressed against the photosensitive drum is set.
Can be maintained at an appropriate value, and is controlled so that the paper does not rub the surface of the photosensitive drum strongly and the toner image is not disturbed.

However, as shown in FIG. 4, in the mechanism provided with the mechanism for swinging the lower guide plate according to the strength of the waist of the paper, even the paper having the same waist strength has different sizes. In this case, there arises a problem that an optimum loop cannot be formed. Particularly, when the lower guide plate is swingably supported by a spring, there is a problem that the paper is excessively pressed toward the photoconductor drum by the reaction force of the spring, and the action of adjusting the loop is improved. There are cases where it cannot be demonstrated. Further, in measuring the waist strength of the sheet, in the example disclosed in Japanese Utility Model Laid-Open No. 62-181953, when the sheet is fed from the sheet feeding cassette,
A means for measuring the size of the loop formed on the paper between the roller and the snubber when the paper is fed out is used. However, using such a small loop to accurately measure the properties of the paper leaves a problem in the reliability of the measured value.

[0008]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the conventional paper guide means, and makes it possible to form an optimum loop on the paper in accordance with the strength of the paper, and the registration roller. An object of the present invention is to provide a means for guiding a sheet toward an image transfer portion by forming a mechanism for guiding the sheet between the apparatus and the photosensitive drum.

[0009]

SUMMARY OF THE INVENTION According to the present invention, a sheet sent from a sheet feeding section and conveyed in a sheet conveying path forms a loop between two roller devices provided in a sheet aligning device. Then, the present invention relates to an apparatus provided with a mechanism for aligning the sheet and aligning the sheet, and sending the sheet from the photosensitive drum toward the image transfer section by the registration roller apparatus provided in the sheet aligning apparatus. In the present invention, in the paper aligning device, a means for measuring the stiffness of the paper is arranged with respect to the loop of the paper formed between the pre-registration roller device and the registration roller device, and A means for adjusting the size of the loop of the paper is provided between the roller device and the photoconductor drum, and the waist strength of the paper and the information on the paper size are used to provide a space between the registration roller device and the photoconductor drum. The pressing means arranged is operated to control the size of the loop of the paper that contacts the photosensitive drum.

Further, in the present invention, when the paper is strong, the loop can be formed small and the angle at which the paper contacts the photosensitive drum can be increased. Further, depending on the properties of the paper, when the paper is stiff, the loop can be set large and the angle at which the loop of the paper and the surface of the photosensitive drum contact can be set small. In addition to the above configuration, a pressure sensor can be used as a means for measuring the stiffness of the paper in the paper aligning device of the present invention. As the paper waist measuring means, the strength at which the arm member is rotated by the reaction force of the paper while the arm member is pressed against the paper with a constant pressure is taken as the value of the waist strength of the paper. It is possible to use a means for measuring the measured value, inputting the measured value to the control device, controlling the angle of swinging the lower guide plate for guiding the paper toward the photosensitive drum, and adjusting the size of the loop. it can.

As described above, by arranging a means for measuring the pressure of the loop with respect to the sheet aligning device in order to measure the stiffness of the sheet, the sheet stiffness is not affected by the sheet size. The strength of can be measured. In addition, the swing angle of the lower guide plate can be adjusted in order to control the size of the loop at the position where the paper contacts the photoconductor drum according to the measurement information of the stiffness of the paper. The angle at which the paper loop contacts the surface of the photosensitive drum can be adjusted to an appropriate value. Therefore, the paper does not rub the toner image formed on the photoconductor drum, and the image transfer function can be excellently performed.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A paper guide device for a photosensitive drum in an image forming apparatus of the present invention will be described with reference to the illustrated example. The example shown in FIG. 1 discloses a mechanism of a main part of an electrophotographic copying machine in which a toner image is formed on a photosensitive drum by using an electrophotographic system and the toner image is transferred onto a sheet by discharge of a transfer corotron 2. ing. In the apparatus shown in FIG. 1, the transfer corotron 2 is arranged corresponding to the photosensitive drum 1, and the paper aligning device 10 is arranged upstream of the position where the toner image is transferred onto the paper. The registration roller device 11 feeds the paper aligned by the above to the image transfer portion.

As in the case of a general copying machine, the sheet aligning device 10 is provided at the leading end of the sheet transport path fed from the paper feed tray, and the pre-registration roller device 12 is provided.
And the registration roller device 11 are arranged at a predetermined interval. Then, in a state where the leading end of the paper is projected into the nip portion of the registration roller device 11, the pre-registration roller device 12 in the upstream portion gives an additional feeding action,
A loop Pr is formed on the paper, and the pressure of the loop of the paper aligns the leading end of the paper so as to uniformly enter the nip portion of the roller device. After that, the sheet is fed toward the image transfer section via the guide section at the front end of the sheet conveyance path arranged on the downstream side of the registration roller device 11.

In the sheet aligning device 10, when the loop Pr is formed on the sheet, the size of the loop is defined by controlling the driving time of the pre-registration roller device. Therefore, in the present invention, when forming a loop in the sheet aligning device, the pressure sensor 15 is arranged corresponding to the top of the loop Pr, and means for measuring the force with which the sheet loop presses the pressure sensor 15. Is used. As the pressure sensor, any pressure detecting means can be used, and the information on the pressure of the loop detected by the pressure sensor is input to the control device 20 and the paper in the downstream portion of the paper aligning device is input. It is used as information for controlling the size of the loop Ps. Further, with respect to the control device of the present invention, a means for the operator to input information on the paper size is provided, and the information on the stiffness of the paper and the information on the paper size are used to allow the operator to control the paper size. The control information of the loop Ps can be output. Note that the paper size information can use the paper information selected by the control device of the copying machine at the time of making a copy, and especially when the operator does not need to input the paper size information. Can also be considered.

In the paper path for guiding the paper toward the photosensitive drum in the downstream portion of the paper aligning device, the lower guide plate 8 and the upper guide plate 5 are arranged so as to face each other. The example shown in FIG. In the above, the upper guide plate 5 is swingably provided via the hinge 6, and the tip of the downstream portion of the upper guide plate 5 is connected to the drive unit 7.
Is used to move up and down. The drive device 7
Can be configured by combining a stepping motor with a pulley that winds a wire, and drives the motor to vertically move the downstream end of the upper guide plate 5 in response to a command from the control device 20. Then, in a state where the upper guide plate 5 is rocked and raised to a position shown by a chain line in the drawing, for example, the size of the loop Ps of the sheet formed between the registration roller device 11 and the photosensitive drum 1 is increased. Can be adjusted, whereby the plunge angle θ at which the paper contacts the surface of the photosensitive drum 1 can be controlled according to the strength of the stiffness of the paper.

In the present invention, instead of using the pressure sensor as described above to measure the stiffness of the paper, an angle detecting sensor may be used as shown in FIG. it can. Then, the arm 18 of the sensor 17 is pressed against the sheet loop Pr, and the state in which the arm 18 is swung by the stiffness of the sheet is output as information on the rotation angle of the shaft supporting the arm. You can
In the method using the sensor, the tip of the arm is configured to have a predetermined weight, and the swing of the arm is detected when the reaction force of the loop of the paper is a certain magnitude or more. Can be used.

In addition, as the sensor, for example,
As disclosed in Japanese Patent Laid-Open No. 3-192050, a device for detecting the rotation angle of the arm can be used.
When the means for detecting the thickness of the paper as shown in the conventional example is used as the means for detecting the stiffness of the paper, the operation arm of the sensor is pressed against the loop of the paper with a predetermined pressure. By using the mechanism, it is possible to obtain the information about the strength of the waist of the paper as the information about the rotation angle of the support shaft of the arm. Then, the waist strength of the paper is measured using the detection means shown in FIG. 2, and the detection information is input to the control device to form the paper on the paper at the position where the paper contacts the photosensitive drum. By adjusting the size of the loop to prevent the paper from sliding on the surface of the photoconductor drum at the image transfer portion, the paper feeding operation can be performed.

As described above, in the present invention, when the loop is formed on the sheet at the sheet aligning device, the stiffness of the sheet is measured and the sheet is fed toward the photosensitive drum. The device can be configured. Then, when controlling the size of the loop of the paper at the position where the paper is sent out from the registration roller device and comes into contact with the photoconductor drum, the electrophotographic copying machine generally used has a strong paper. On the other hand, if the loop is set small and the plunge angle θ of the sheet is set large, the transfer action of the toner image on the sheet can be performed in a good state. On the other hand, depending on the characteristics of the electrophotographic copying machine, control is performed such that a large loop is set for paper with strong stiffness,
It is also possible to set the angle θ at which the paper enters the photosensitive drum to be small. Of course, when the loop of the paper is formed at the position where the paper comes into contact with the photoconductor drum as described above, and the entry angle of the paper with respect to the photoconductor drum is controlled, the characteristics of the electrophotographic copying machine and the paper It is necessary to previously input information on the correlation with the characteristics of the above into the control device.

As shown in FIG. 1, the detection means arranged in the sheet aligning device obtains information about the stiffness of the sheet, and determines the size of the loop at the position where the sheet contacts the photosensitive drum. For the purpose of control, not only the upper guide plate can be swung, but a mechanism for swinging the lower guide plate can also be configured. In the example shown in FIG. 3, in order to adjust the size of the loop of the paper, a mechanism for oscillating by interlocking the upper and lower guide plates is arranged. In the device shown in FIG. 3, two guide plates, an upper guide plate 5 and a lower guide plate 8, are swingably provided via hinges 6 and 8a arranged on the upstream side, and one drive device 7 is provided. A mechanism for swinging the two guide plates in conjunction with each other is configured. Also,
As in the case of FIG. 1, the driving device 7 can be configured by combining a stepping motor and a wire winding mechanism, and a wire for supporting the guide plate via the driving device according to a command from the control device. Take up and swing the guide plate.

Therefore, as described above, at the position for guiding the sheet toward the photoconductor drum, the two guide plates are interlocked and swung, whereby the registration roller device 11 is moved.
The sheet fed from the sheet is fed in a state where a sheet loop Ps is formed between the upper and lower guide plates and a predetermined plunge angle θ is set with respect to the photosensitive drum 1. The information for swinging the guide plate is the same as in the case of FIG.
When forming a paper loop Pr between the two roller devices that form the paper aligning device, the control device 20 converts the pressure information of the loop into the stiffness of the paper and outputs it as control information. I will let you.

When the means for measuring the stiffness of the paper of the present invention is provided, the paper aligning device is not limited to the mechanism for aligning the paper between the two roller devices. In addition, the present invention can be applied to a paper aligning device of a type in which a gate member is arranged upstream of the registration roller device and paper alignment is performed between the gate and the registration roller device. Further, in the apparatus of the present invention, the operator inputs the information of the weight (g / square meter) of the paper using the ten-key and corresponds to the photoconductor drum without using the means for measuring the stiffness of the paper. It is also possible to control the size of the paper loop at the position. However, in that case, the influence of humidity around the copier or the like occurs, so that if the correction information such as temperature and humidity is set in the control device, more accurate control operation can be performed. . Then, by using the information on the stiffness of the paper obtained by the reaction force of the loop and the information on the paper size, by controlling the size of the loop at the position where the paper is pressed against the photosensitive drum, The function of image transfer can be excellently performed.

[0022]

Since the paper guide device for the photosensitive drum in the image forming apparatus of the present invention has the above-mentioned structure, it is used in the paper aligning device in order to measure the stiffness of the paper. By arranging the means for measuring the pressure of the loop, the stiffness of the paper can be measured without being affected by the paper size. Also, in order to control the size of the loop at the position where the paper contacts the photosensitive drum, the swing angle of the lower guide plate is controlled according to the measurement information of the stiffness of the paper and the information of the paper size. Can be adjusted so that the angle at which the paper loop contacts the surface of the photosensitive drum can be adjusted to an appropriate value. Therefore, the paper does not rub the toner image formed on the photoconductor drum, and the image transfer function can be excellently performed.

[Brief description of drawings]

FIG. 1 is a side view showing a configuration of a paper feeding device of the present invention.

FIG. 2 is an explanatory view of another embodiment of the loop reaction force measuring device of the invention.

FIG. 3 is a side view showing another configuration of the guide member at the tip portion.

FIG. 4 is an explanatory diagram showing a configuration of a conventional device.

[Explanation of symbols]

1 photoconductor drum, 5 upper guide plate, 7 driving device, 8 lower guide plate, 10 paper aligning device,
11 registration roller device, 12 pre-registration roller device, 15 pressure sensor, 17 angle detection sensor, 18 arm member, 20 control device.

Claims (1)

[Claims] 1. A sheet fed from a sheet feeding section and fed in a sheet feeding path is aligned by forming a loop between two roller devices provided in a sheet aligning device, and is provided in the sheet aligning device. By the registration roller device,
In a device provided with a mechanism for feeding the image from the photoconductor drum toward the image transfer portion, with respect to the loop of the sheet formed by the sheet aligning device,
A means for measuring the stiffness of the paper is arranged, and a means for adjusting the size of the loop of the paper is provided between the registration roller device and the photosensitive drum, and information on the stiffness of the paper is provided. And the information on the paper size, the pressing means arranged between the registration roller device and the photoconductor drum is operated to control the size of the loop of the paper in contact with the photoconductor drum. Paper guide device to the photosensitive drum in the machine.