JP2826891B2 - Image forming device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus represented by, for example, a facsimile, a copying machine, a printer, etc. The present invention relates to an image forming apparatus.

2. Description of the Related Art Conventionally, an image forming apparatus such as a copying machine or a printer, which is well known, conveys a recording material from a supply unit such as a cassette to an output unit via an image forming unit.
In this case, it is necessary to form an image after the recording material is fed, and to control the recording material at a constant timing until the recording material is discharged. In particular, since the timing from the sheet feeding to the image formation is related to the image forming position on the recording material, accurate conveyance of the recording material is required. Further, if the conveyance speed of the recording material during image formation is not constant, a shift in magnification of the image occurs, and the image expands and contracts. In particular, in the case of an image forming apparatus in which a plurality of image recording units are juxtaposed, a shift occurs between images recorded by each image recording unit. In the case of a color image recording apparatus, this appears as color misregistration or color unevenness, and has become a serious defect on the formed image. In order to prevent such inconvenience, it is necessary to accurately transmit the conveying force of the conveying unit to the recording material and to make the conveying speed constant.

In consideration of the above points, various means have been devised for improving the transport system of the image forming apparatus. For example, there is a unit that sends out a recording material by a pair of rollers and regulates a conveyance direction by a guide. Since this means sends out the recording material by the pressure between the rollers, the conveying force is strong, and the structure is simple and the structure is simple. However, the roller pair must be arranged at a position shorter than the minimum length of the recording material to be used, which is not suitable for feeding paper smaller than a normally used size such as a postcard or business card size.

Further, it cannot be used in a place where a recording material must be conveyed in a state of non-contact with a recording surface, such as during a period from transfer by an electrophotographic drum to fixing.

As another means, there is also known one in which the leading end of a recording material is conveyed by being gripped by a gripper and pulled. In this case, once the gripper grasps the recording material, the conveying force is strong and certain, but the mechanism is complicated. Furthermore, it is necessary to match the timing of inserting the leading end of the recording material into the gripper, and there is a disadvantage that the recording material is left with a trace of the gripper.

Further, as another means, there is a method in which air is blown from a back surface of an endless belt having a large number of holes with a fan or the like, and a recording material is adsorbed on the belt by a negative pressure generated at that time and conveyed. In this case, since only the contact from the back side of the recording material is made, it is used to convey the recording material before fixing the electrophotograph.However, the conveyance force is weak and the dust and toner inside the machine are attracted. There is a disadvantage that the surface becomes dirty.

Therefore, an image forming apparatus using a transport belt using electrostatic force as shown in FIG. 5 has been proposed. In FIG. 5, reference numeral 301 denotes a scanner which reads a document and converts it into an electric signal. This scanner section
A signal based on the signal converted in 301 is provided as a drive signal to the recording head unit 305 of the printer unit 302. The recording paper as one of the recording materials stored in the cassette 303 is sent one by one to the belt transport unit 304 as needed. When the recording paper passes through the belt transport unit 304, an image is recorded by the recording head 305, and the fixing and discharging unit 3
It is sent to the tray 420 via 07. Reference numeral 306 denotes a recovery cap unit, which has a function of keeping the recording head unit 305 in a printable state at all times.

In the scanner section 301, reference numeral 401 denotes a document, and 402 denotes a document scanning unit for scanning the document. Document scanning unit
The 402 includes a rod array ins 403 1: 1 type color separation line sensor (color image sensor) 404 and an exposure unit 405. At least when the document scanning unit 402 moves and scans in the direction of arrow A to read the image of the document 401 on the document table, the exposure unit 405 in the document scanning unit 402
Is turned on, and the reflected light from the original 401 is guided by the rod array lens 403 and condensed on a 1: 1 color separation line sensor (hereinafter referred to as a reading sensor) 404, which is a color information reading sensor. The color image information of the document is read for each color and converted into an electric digital signal. This digital signal is sent to the printer unit 302. A drive signal based on these signals is supplied to the recording head for each color, and the liquid is ejected.

In the belt transport section 304 of the above-described apparatus, an endless transport belt 201 is stretched between two rollers, and a charging roller 204 and a cleaner 307 are disposed around the belt. The charging roller 204 is connected to a high-voltage power supply (not shown). Further, an insulating layer is formed on the surface of the transport belt 201, and a charge is placed on the charge roller 204 so that the transfer material is electrostatically and strongly attracted by the charge. The reason for strong adsorption is that the distance between the recording head 305 and the conveyance belt 201 is as narrow as 1 mm or less, so that even if the transfer material rises even a little, a jam occurs. But also.

The cleaner 307 includes a blade 281 and an absorber 283, and operates during or after printing by the recording head 305 in a certain sequence.

(Problems to be Solved by the Invention) However, in such a conventional technique, as described above, charges are placed on the conveyor belt 201 by the charging roller 204, and the characteristics thereof are as shown in FIG. In addition, it is known that the belt exhibits a certain rising characteristic until the surface potential of the belt becomes a potential sufficient for adsorption. This is due to factors such as the surrounding environment, the state of the conveyor belt, and the residual potential of the conveyor belt. For example, in the drawing, the characteristic that the conveyor belt 201 becomes the saturated (assumed) potential V at the third rotation is shown. Is shown. At this time, for example, if the recording material is placed at the first rotation or less after the conveyance belt 201 starts rotating, a sufficient suction force cannot be obtained. In this case, there is a problem that the leading end of the transfer material is particularly lifted up, so that the paper cannot pass between the recording head unit 305 and the transport belt 201 and a jam occurs.

Another problem is a conveyor belt on which a transfer material is placed.
If the surface of the transfer belt 201 is stained with ink, not only does the transfer material become stained on the back, but also the apparent resistance value of the insulating layer on the surface of the conveyor belt 201 decreases, and sufficient charge cannot be applied. Things happened. This is because, for example, even if a cleaning operation is performed after printing is completed, ink mist floating inside the machine adheres for a long time, and especially after leaving for a long time, such as the first copy in the morning, the transfer belt In many cases, the ink adheres to the ink and causes the above-mentioned trouble. In addition to the ink, the surface of the conveyor belt attracts fine dust and dust,
As a result, there is also a problem that the friction coefficient is reduced.

The present invention has been made in order to explain the above-described problems of the related art, and its purpose is to sufficiently impart an electric suction force to a conveying unit that conveys a recording material,
Recording material can always be transported reliably without being affected by ink contamination. An object of the present invention is to provide an image forming apparatus with clear images.

(Means for Solving the Problems) In order to achieve the above object, according to the present invention, there is provided a conveying unit for mounting a recording material and conveying the recording material from a supply unit to a discharge unit; A recording unit for recording an image, a cleaning unit having a cleaning blade at a position facing the surface of the transporting unit for cleaning the surface, and a cleaning blade and an absorber for absorbing an edge mark of the cleaning blade remaining on the transporting unit; Wherein the absorber is set so as to come into contact with a position where an edge mark of the conveying means remains after the cleaning blade is separated from the conveying means.

(Operation) By providing a cleaning means, it is possible to prevent adverse effects due to ink stains, and to ensure more reliable conveyance and image clarity.

(Example) Hereinafter, the present invention will be described based on an illustrated example. However, since the basic configuration of the image forming apparatus is the same as that of the conventional apparatus shown in FIG. 5, the characteristic portion will be described with reference to FIG.

In FIG. 1, reference numeral 20 denotes a registration roller provided on the side for supplying a recording material. A sensor 20S for detecting a recording material is provided near the registration roller 20. On the other hand, a discharge roller 21 and a sensor 21S for detecting the recording material are provided on the discharge side.

A conveyance belt 1 is provided between the registration roller 20 and the discharge roller 21 as conveyance means for conveying the recording material in the direction A. A recording head unit 8 as recording means is disposed above the conveyor belt 1.

The surface of the conveyor belt 1 is formed of an insulating layer, and its volume resistance is preferably 10 ¹⁴ Ω · cm or more. The transport belt 1 is formed endlessly, and is stretched around the driving roller 2 and the driven roller 3. A drive motor (not shown) is connected to the drive roller 2 so as to rotate in the direction of arrow A in the figure.

Reference numeral 4 denotes a charging roller as a charging means, which is a high voltage power supply.
HV, and is pressed against the transport belt by springs 5 provided at both ends. The driven roller 3 is electrically grounded, sandwiches the conveyor belt 1 between the driven roller 3 and the charging roller 4, and
By applying a high voltage of about 2 KV, a potential is left on the surface of the conveyor belt 1. Reference numeral 6 denotes a suction member, which is connected to an electric ground. This suction member is provided for injecting electric charge into the recording material being conveyed,
In the present embodiment, for example, it is constituted by the conductive brush 6B and the resin sheet 6S, and the tips of these two members are in contact with the surface of the conveyor belt 1.

A platen 7 disposed inside the conveyor belt 1 is a platen for keeping the conveyor belt of a portion facing the recording head unit 8 flat, and the recording head unit 8 is fixed to the recording head unit 8 by pins 7P provided on the platen 7. Are kept constant.

Reference numeral 9 denotes a belt cleaning unit as a cleaning unit, which includes a blade 10 and an absorber 11, each of which is independently supported by support tables 12 and 13, respectively.
Each of these supports 12 and 13 independently has a rotary drive unit for making contact with the conveyor belt 1.

Here, after the support table 12 supporting the blade 10 abuts on the transport belt 1 and separates from the transport belt 1, the rotation drive is performed so that the support body 13 supporting the absorber 11 abuts on the transport belt 1. The means is provided with control means 16. More specifically, the operations of the two will be described. First, the conveyor belt 1 is rotated to bring the blade 10 into contact, and after a predetermined time has elapsed, the belt is stopped and the blade 10 is released. Then, an ink mark along the edge of the blade 10 remains on the belt. This position is brought to a position where the absorber 11 comes into contact, and the conveyor belt 1 is stopped again to bring the absorber 11 into contact with the ink mark. I try to absorb it. Then, after a certain time has elapsed, the absorber 11 is released, and the cleaning operation is completed.

A drive motor (not shown) connected to the drive roller 2 of the transport belt 1 is provided with a control means 15 for transporting the recording material so that the transport roller 1 is sufficiently charged by the charging roller 4. It is set to make at least one rotation before performing.

In the following, the operation of the apparatus of this embodiment having the above configuration will be described with reference to the sequences of FIGS. 1 and 2, and the contents of the present invention will be further clarified.

First, when a copy button is pressed to start a printing sequence, a recording material is conveyed from a paper supply unit (not shown) and reaches a registration roller 20. At this time, since the sensor 20S immediately before the registration roller 20 detects the recording material, the cleaning sequence starts here (step 1).

The cleaning sequence is shown in step 2. First, the conveyor belt 1 starts rotating, and at the same time, the blade 10 comes into contact. Then, release the blade 10 After a certain period of time t ₁ has elapsed. The time t ₁ is the length of a margin of tender time the conveyor belt is rotated 1 (step 2-1). When the blade 10 is released, the conveyor belt 1 may be kept rotating or once stopped. Then certain time t ₂ Release the blade 10 stops the conveyor belt 1 after the lapse. If, when stopping the conveyor belt 1 when release the blade 10 is re-started, Stop time t ₂ has elapsed. This is because an ink mark along the edge of the blade 10 remains on the transport belt, and this position is moved to a position where the absorber 11 contacts. Thus the time t ₂ is the time the ink traces can when released blade 10 is moved to the contact position of the absorbent body 11 (step 2-2). Then, contacting the absorbent body 11 to the conveyor belt 1, then release the after absorber 11 a certain amount of time t ₃ has elapsed, the cleaning sequence is completed. At this time t ₃ , the absorber 11
This is the time until the ink trace on the belt is sufficiently absorbed, and is set in the control means 16 in advance (step 2-3).

When the cleaning sequence is completed, the transport belt 1 is started again, and at the same time, the high-voltage power supply HV connected to the charging roller 4 is also turned on. Then, by rotating the registration roller 20 after a certain time t ₄ has passed, feeding the recording material conveying belt 1. At this time, the time t ₄ is a time until the surface potential of the conveyor belt 1 reaches the set value V as shown in FIG. 6, and is set in the control means 15 in advance. This is called pre-charging (step 3).

Here, the recording material passes between the suction member 6 and the transport belt 1 after being sent out by the registration roller 20. At this time, the transport belt 1 is charged by the charging roller 4, and the recording material is polarized by this potential and is attracted. Further, a charge is injected into the recording material by the suction member 6, and the recording material is conveyed while being more strongly suctioned.

Subsequently, the recording material is conveyed while being printed by the recording head unit 8. When the sensor s ₁ detects the paper trailing edge in the case of single mode, and, when in the case of large number mode which detects the paper trailing edge of the last sheet, the high-voltage power supply Hv to OFF, the further the recording sheet discharge roller When the paper is conveyed by 21, the rear end of the paper (the rear end of the final paper) is detected by the paper discharge sensor 21S. Then, the conveyance belt 1 stops, the operation of the other image recording units ends, and the image forming sequence ends (step 4).

In the above embodiment, the cleaning sequence of step 2 is started after the sensor 20S detects the recording paper. However, when the cleaning sequence takes a long time and the recording paper reaches the registration roller 20 before the end of the cleaning sequence, Alternatively, the cleaning sequence may be started at the time of the start, the recording material may be made to stand by by the registration roller 20, and the cleaning sequence may be ended.

FIG. 3 shows a second embodiment of the present invention.
However, since the configuration of the apparatus in this embodiment is substantially the same as that of the first embodiment shown in FIG. 1, a flowchart is shown in FIG. 3 and the description will be made based on this flowchart.

In this embodiment, an example is shown in which cleaning by a blade is performed during a series of sequences from charging to printing.

First, when the print sequence is started by pressing the copy button, the same operation as in step 1 of the first embodiment is performed (step 11). Here, the conveyor belt 1 starts rotating,
At the same time, the blade 10 comes into contact, and at this time, the charged high-voltage power supply is also turned on. Hereinafter, the sequence proceeds to step 3 and step 4 in the first embodiment. In the latter half of step 4, after the sensor 21S detects the trailing edge of the sheet, the process proceeds to step 2-2 of the cleaning sequence (step 12), and The process proceeds to steps 2-2 and 2-3 of the first embodiment and ends (step 1).
3).

In this embodiment, the cleaning blade 10 is always in contact with the conveyor belt 1 during printing by the recording head unit 8, which is disadvantageous in terms of conveyance accuracy. This has the effect of shortening the time.

FIG. 4 shows a third embodiment. This embodiment also shows the sequence of operation in the same manner as in the second embodiment.

In this embodiment, the high-voltage power supply is turned on even during the cleaning sequence, a certain amount of electric charge is given in advance, and then the pre-charging starts. In this way, before charging at time t ₄ is shorter, measurably is overall speed up, there is an effect that.

As described above, the present invention has been described based on the embodiments. However, the present invention can be performed only by pre-charging before starting the transport operation or only by the cleaning operation, and improvement in transportability can be expected.

(Effects of the Invention) The present invention has the above-described structure and operation. If a cleaning means is provided in a conveying means, and the cleaning means is constituted by a cleaning blade and an absorber to surely eliminate ink traces, The recording material can be reliably conveyed, and stable image formation can be achieved.

[Brief description of the drawings]

FIG. 1 is an enlarged view showing a main part of the image forming apparatus according to the first embodiment of the present invention, FIG. 2 is a flowchart showing the operation of the apparatus of the embodiment, and FIG. FIG. 4 is a flowchart for a third embodiment of the present invention, FIG. 5 is a diagram showing a conventional image apparatus, and FIG. 6 is a change in surface potential of a conveyor belt (conveying means). It is a graph showing an example. DESCRIPTION OF SYMBOLS 1 ... Conveying means (conveying belt) 4 ... Charging means (charging roller) 8 ... Recording means (recording head section) 9 ... Cleaning means (cleaning section) 10 ... Blade 11 ... Absorber

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tohru Kobayashi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Masatoshi Katai 3-30-2 Shimomaruko, Ota-ku, Tokyo Within Canon Inc. (72) Inventor Tatsuo Mitomi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Masaharu Nemura 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Yasuyuki Takanaka 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) References JP-A-4-31070 (JP, A) JP-A-1-122844 (JP, A JP-A-2-52829 (JP, A) JP-A-62-288843 (JP, A) JP-A-57-179945 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) B41J 13/22 B41J 13/08 B41J 29 / 00 G03G 15/00 B65H 5/00-5/02

Claims (1)

(57) [Claims] 1. A conveying means for mounting a recording material and conveying the recording material from a supply unit to a discharge unit, a recording means for recording an image on the recording material, and a position facing a surface of the conveying means. A cleaning means for cleaning the surface, having a cleaning blade and an absorber for absorbing the edges of the cleaning blade remaining on the transporting means, after the cleaning blade is separated from the transporting means, An image forming apparatus, which is set so as to contact a position where an edge mark of a conveying unit remains.