JP2005179041A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a decrease in image quality due to cutting burr of a recording medium in an image forming apparatus.
A toner image formed on an image carrier is transferred to a recording medium while the recording medium is being conveyed, and the recording medium after the image transfer is placed in a belt fixing device 24, and an unfixed toner image on the recording medium. Is fixed on the recording medium. In such an image forming apparatus, a leveling device that presses the leading end of the recording medium with a leveling member and presses the cutting burr is provided in the conveyance path P of the recording medium. The leveling member may be in the form of a roller and repeatedly press the recording medium by the rotation of the leveling member. At that time, it is preferable to form irregularities on the peripheral surface. The leveling member may be made of an elastic material.
[Selection] Figure 1

Description

  The present invention relates to an image forming apparatus such as a copy, a printer, a facsimile, a plotter, or a complex machine thereof. For example, the present invention relates to an electrophotographic image forming apparatus that directly or indirectly transfers a toner image formed on an image carrier and records the image on a recording medium such as a sheet / OHP film.

  Conventionally, in an electrophotographic image forming apparatus, a drum-like or belt-like image carrier is rotated to perform charging, writing, and development, and a toner image is formed on the image carrier, and the toner image is directly or intermediately formed. The image is recorded on the recording medium by transferring it indirectly to the recording medium via a transfer member and placing the recording medium in a fixing device to fix the unfixed toner image.

  Generally, in a fixing device, a fixing nip is formed between a fixing member such as a fixing roller and a fixing belt that is heated to a fixing temperature by a heat source and a pressing member such as a pressure roller and a pressure belt that are pressed against the fixing member. Then, the fixing member is rotated and driven through the recording medium on which the unfixed toner image is placed in the fixing nip, the pressure member is driven to rotate, and heat and pressure are applied to the recording medium while sandwiching and conveying the recording medium. It was heated and melted and pressed onto the recording medium.

  By the way, in this type of image forming apparatus, in recent years, due to a demand for energy saving, a zero energy standby mode (Zero Energy Standby Mode-ZESM) is performed during standby. In the zero energy standby mode, during non-image formation, the power supply to the heat source is cut to reduce energy consumption, and the heat source is turned on when the image forming operation starts, and the fixing member of the fixing device is raised to the fixing temperature. Warm up.

  For this reason, it is necessary to reduce the heat capacity of the fixing member, increase the temperature responsiveness, and shorten the startup time until fixing is possible to about 10 seconds, thereby saving energy and improving user convenience.

  For this reason, recently, a fixing device uses a fixing belt as a fixing member. For example, as shown in FIG. 6, fixing is performed on a fixing roller 1 and a heating roller 3 heated to a fixing temperature by an internal heat source 2. Increasingly, the belt 4 is wound around and the pressure roller 5 is pressed against the fixing belt 1 through the fixing belt 4 to form the fixing nip n. Reference numeral 8 in the figure denotes an entrance guide plate that guides the recording medium 7 after image transfer having the unfixed toner image 6.

JP 2003-26344 A Japanese Patent No. 3209799

  However, in the belt fixing apparatus using the fixing belt 4, when the recording medium 7 after image transfer enters and is guided by the entrance guide plate 8 and abuts against the fixing belt 4, the recording medium 7 is not shown due to the shock. There is a problem that the relative position of the image carrier is slightly displaced and transfer displacement occurs. In particular, as shown in FIG. 7, when the cutting burr 9 is at the image recording surface side tip of the recording medium 7, the shock is further increased, and the transfer deviation becomes larger as the paper is thicker. There is a problem that the transfer is liable to be caught.

  SUMMARY OF THE INVENTION Accordingly, a first object of the present invention is to prevent a decrease in image quality caused by cutting burr of a recording medium in an image forming apparatus.

  A second object of the present invention is to achieve the first object with a simple structure and in a simple method.

  A third object of the present invention is to reliably achieve the first object corresponding to various types of recording media.

  A fourth object of the present invention is to effectively achieve the first object.

  A fifth object of the present invention is to achieve the first object by preventing a transfer deviation that occurs particularly when a recording medium after image transfer enters a belt fixing device.

  According to a first aspect of the present invention, there is provided an image forming apparatus for recording an image on a recording medium while conveying the recording medium so as to achieve the first object. It comprises a leveling device that presses the medium and smoothes the cutting burrs.

  Then, when the recording medium is transported to record an image on the recording medium, the recording medium is pressed using a leveling member and the cutting burr is leveled by a leveling device provided in the recording medium transport path.

  According to a second aspect of the present invention, in order to achieve the second object described above, in the image forming apparatus according to the first aspect, the leveling member is formed as a roller and the recording medium is pressed by the rotation of the leveling member. It is characterized by that.

  Then, the roller-shaped leveling member is rotated to press the recording medium, and the cutting burr is leveled.

  The invention according to claim 3 is characterized in that, in order to achieve the third object described above, in the image forming apparatus according to claim 2, irregularities are formed on the peripheral surface of the leveling member.

  Then, the recording medium is pressed by the unevenness formed on the peripheral surface of the leveling member, and the cutting burr is leveled.

  The invention according to claim 4 is characterized in that the leveling member is made of an elastic material in the image forming apparatus according to any one of claims 1 to 3, in order to achieve the fourth object described above. To do.

  Then, the recording medium is elastically pressed by the leveling member to level the cutting burr.

  In the image forming apparatus according to any one of claims 1 to 4, the invention according to claim 5 repeatedly presses the recording medium by reciprocating the leveling member in order to achieve the fourth object. It is characterized by.

  Then, the leveling member is reciprocated to repeatedly press the recording medium to level the cutting burr.

  The invention according to claim 6 is to transfer the toner image formed on the image carrier onto the recording medium in the image forming apparatus according to any one of claims 1 to 5, in order to achieve the fifth object described above. Then, the recording medium after the image transfer is placed in a belt fixing device, and the unfixed toner image on the recording medium is fixed on the recording medium.

  Then, the toner image formed on the image carrier is transferred to a recording medium, the recording medium after the image transfer is placed in a belt fixing device, and an unfixed toner image on the recording medium is fixed on the recording medium in advance. A leveling device provided in the medium transport path presses the recording medium using a leveling member to level the cut burrs.

  According to the first aspect of the present invention, in the image forming apparatus, when the recording medium is transported to record an image on the recording medium, the leveling device provided in the transport path of the recording medium is used to record using the leveling member. Pressing the media and smoothing the cutting burrs prevents image quality deterioration caused by cutting burrs on the recording medium, such as a large shock caused by the cutting burrs and transfer deviation caused by the cutting burrs. can do.

  According to the second aspect of the present invention, the roller-like leveling member is rotated to press the recording medium and the cutting burrs are leveled. A reduction in image quality due to cutting burrs of the recording medium can be prevented at a cost.

  According to the third aspect of the present invention, the recording medium is pressed by the unevenness formed on the peripheral surface of the leveling member and the cut burrs are leveled. The cutting burrs having different shapes can be leveled, and the deterioration of the image quality due to the cutting burrs of the recording medium can be prevented.

  According to the fourth aspect of the invention, since the recording medium is elastically pressed by the leveling member and the cutting burrs are leveled, the leveling member having a large friction coefficient μ is efficiently and effectively cut. The image quality can be prevented from being deteriorated due to the cutting burr of the recording medium.

  According to the fifth aspect of the present invention, since the leveling member is reciprocated to repeatedly press the recording medium and level the cutting burrs, the image quality is effectively reduced due to the cutting burrs of the recording medium. Can be prevented.

  According to the sixth aspect of the present invention, the toner image formed on the image carrier is transferred to a recording medium, the recording medium after the image transfer is placed in a belt fixing device, and an unfixed toner image on the recording medium is transferred. When fixing to the recording medium, the leveling device provided in advance in the recording medium conveyance path presses the recording medium using a leveling member and leveles the cutting burrs. Image quality caused by cutting burr of the recording medium by preventing the relative displacement between the recording medium and the image carrier due to the shock when hitting the fixing belt when entering the fixing device. Can be prevented.

The best mode for carrying out the present invention will be described below with reference to the drawings.
FIG. 1 shows an overall schematic configuration of an internal mechanism in an electrophotographic color printer according to the present invention.

  Reference numeral 100 in the drawing denotes a printer main body. In the apparatus main body 100, a recording medium conveyance path P is provided obliquely from the lower right to the upper left in the drawing.

  On the recording medium conveyance path P, four monochrome image forming units 10Y, 10M, 10C, and 10B of yellow, magenta, cyan, and black are arranged in order from the lower right to the upper left along the conveyance path P to form a tandem type. Prepare. Each monochromatic image forming means 10 includes image carrier units 12Y, 12M, 12C, and 12B and developing units 13Y, 13M, 13C, and 13B, and is detachable from the apparatus main body 100. Each image carrier unit includes a drum-like image carrier 14Y / 14M / 14C / 14B.

  On such monochromatic image forming means 10Y, 10M, 10C, and 10B, the writing unit 16 is provided obliquely along the monochromatic image forming means 10.

  On the other hand, an endless belt-like recording medium carrier 18 is stretched under the monochromatic image forming means 10Y, 10M, 10C, and 10B with the recording medium conveyance path P interposed therebetween. In the illustrated example, the recording medium carrier 18 is wound around four support rollers 19 and is in contact with the image carriers 14Y, 14M, 14C, and 14B, and a part thereof is provided along the recording medium conveyance path P. It is possible to run counterclockwise in the figure by the driving device.

  Inside the recording medium carrier 18, backup rollers 20Y, 20M, 20C, and 20B and transfer brushes 21Y, 21M, 21C, and 21B are arranged corresponding to the image carriers 14Y, 14M, 14C, and 14B, respectively. . The backup rollers 20Y, 20M, 20C, and 20B bring the recording medium carrier 18 and the recording medium into close contact with the image carriers 14Y, 14M, 14C, and 14B. The transfer brushes 21Y, 21M, 21C, and 21B are supplied with a transfer bias from a power source (not shown). In the illustrated example, it is a transfer brush, but it may be a non-contact charger.

  Along the recording medium conveyance path P, a registration roller pair 23 is provided at an upstream position of such a recording medium carrier 18, and a belt fixing device 24 is provided at a downstream position. The belt fixing device 24 includes a discharge roller pair 27 at the outlet.

  A reversing unit 29 is provided downstream of the belt fixing device 24 and attached to the apparatus main body 100. The reversing unit 29 discharges the recording medium as it is, reverses it and discharges it, or returns it to the apparatus main body 100 again.

  Further, at the downstream position of the belt fixing device 24, the recording medium conveyance path P is branched to form a reverse discharge path P 1, and the recording medium is discharged to the discharge stack section 30 on the apparatus main body 100 before that. A discharge roller pair 31 is provided.

  On the other hand, below the recording medium carrier 18, a refeed unit 33 for guiding and refeeding the recording medium reversed by the reversing unit 29 along the extending direction between the pair of guide plates 32. Place it diagonally.

  Below the re-feed unit 33, the paper feed cassettes 34 are provided in two upper and lower stages. In the paper feed cassette 34, recording media such as plain paper, OHP film, cards, postcards and the like having different sizes are stacked and stored. Then, a paper feeding unit 35 for separating and feeding the recording media one by one is provided.

  On the right side of the sheet feeding unit 35 in the drawing, there is a recording medium conveyance path P that guides the recording medium fed from the sheet feeding unit 35 and the recording medium re-feeded through the re-feeding unit 33 to the registration roller pair 23. A paper feed path P2 is provided.

  Further, a manual feed section is provided on the right side of the apparatus main body 100 in the drawing, and a manual feed tray 36 is attached to the manual feed section so as to be freely opened and closed. The manual feed unit is provided with a paper feed unit 37 for separating and feeding the recording media on the manual feed tray 36 one by one, and the recording medium fed from the paper feed unit 37 is guided to the registration roller pair 23. A manual paper feed path P3 of the medium transport path P is provided.

  Now, when recording an image on a recording medium using this color printer, for example, the sheet feeding unit 35 is selectively driven based on a signal from the host, and the recording medium in one sheet feeding cassette 34 is set to one. The sheets are separated and fed out, put into the paper feed path P2, and abutted against the registration roller pair 23 to stop. Alternatively, during manual feeding, the manual paper feeding unit 37 is driven to separate and feed out the recording media on the manual tray 36 one by one, put into the manual paper feeding path P3, and abut against the registration roller pair 23 to stop.

  On the other hand, in each of the monochromatic image forming means 10Y, 10M, 10C, and 10B, the individual image carriers 14Y, 14M, 14C, and 14B are rotated, and yellow, magenta, cyan, and black monochromatic toner images are respectively formed on the image carriers. Form. At the same time, one of the support rollers 19 is rotationally driven by a drive motor (not shown), the other support rollers 19 are driven to rotate, and the recording medium carrier 18 is rotated and conveyed.

  Then, the registration roller pair 23 is rotated in synchronization with the rotation of the image carrier, and the recording medium is passed through the recording medium conveyance path P between the monochromatic image forming means 10Y, 10M, 10C, and 10B and the recording medium carrier 18. The recording medium is transported by the traveling of the recording medium carrier 18. Along with the conveyance, the single color toner images on the individual image carriers 14Y, 14M, 14C, and 14B are transferred by the transfer brushes 21Y, 21M, 21C, and 21B, and the combined full-color images are recorded on the recording medium.

  The recording medium after the image transfer is sent to the belt fixing device 24 to fix the transferred image, and then discharged by the discharge roller pair 27. Then, when discharging in the face-down state, switching is performed with a switching claw (not shown), leading to the reverse discharge path P1 of the recording medium conveyance path P, discharged by the discharge roller pair 31, and the page on the discharge stack unit 30. Stack in order.

  When discharging in the face-up state, it is switched by a switching claw (not shown), led to the reversing unit 29, and discharged straight as it is.

  Similarly, when recording on the back side of a recording medium on which one side has been recorded, it is similarly switched by a switching claw (not shown) and led to the reversing unit 29, reversed by the reversing unit 29, and then led to the refeed unit 33. Then, the sheet is again put in the sheet feeding path P2 of the recording medium conveyance path P and is abutted against the registration roller pair 23 and stopped.

  Then, it is again put in the recording medium conveyance path P, sent between the monochromatic image forming means 10Y, 10M, 10C, and 10B and the recording medium carrier 18, and separately provided on the back surface as image carriers 14Y, 14M, 14C, and 14B. The single-color toner image formed on the sheet is transferred to record a composite full-color image, which is then fixed by the belt fixing device 24. To do.

FIG. 2 shows an overall schematic configuration of the belt fixing device 24.
Reference numeral 40 in the figure denotes a fixing housing having an inlet 41 for the recording medium after image transfer and an outlet 42 for the recording medium after image fixing.

  A fixing roller 44 is rotatably provided inside the fixing housing 40. In the illustrated example, the fixing roller 44 includes a cored bar 45 and an elastic layer 46 made of a heat-resistant porous material that covers the cored bar 45.

  A heating roller 47 is rotatably provided inside the fixing housing 40. The heating roller 47 has a heat source 48 made of, for example, one or a plurality of halogen lamps inside, and detects the temperature of the heating roller 47 by providing a thermistor 49 as a temperature detection member outside.

  An endless fixing belt 50 that conveys the recording medium is wound around the fixing roller 44 and the heating roller 47. Then, the heating roller 47 is urged away from the fixing roller 44 by an urging member (not shown), and the fixing belt 50 is stretched with a predetermined tension.

  The fixing roller 44 is urged by an urging member (not shown) and a pressure roller 52 having a heat source 53 is pressed against the fixing roller 44 with the fixing belt 50 interposed therebetween, so that the fixing is performed between the fixing belt 50 and the pressure roller 52. A nip N is formed.

  The fixing roller 44 has an axis sandwiched between two straight lines that connect the axis of the fixing roller 44 and the axis of the heating roller 47, and the axis of the heating roller 47 and the axis of the pressure roller 52 with the axis as the apex. Is in contact with the pressure roller 52 so as to form an acute angle. As a result, the first fixing nip A where the pressure roller 52 contacts only the fixing belt 50 at a portion where the pressure roller 52 does not face the fixing roller 44, and the first contact where the pressure roller 52 contacts the fixing roller 44 via the fixing belt 50. 2 fixing nip portion B is formed to sandwich the recording medium and to be heated.

  An application roller 55 for applying offset prevention oil and a cleaning roller 56 for cleaning the peripheral surface of the fixing belt 50 are pressed against the fixing roller 44 with the fixing belt 50 interposed therebetween. Inside the fixing housing 40, an inlet guide plate 58 that guides the recording medium after image transfer from the inlet 41 toward the fixing nip A is provided.

  Then, the heating roller 47 is heated by the heat source 48 and the pressure roller 52 is heated by the heat source 53 to raise the temperature of the fixing belt 50 to the fixing temperature, while rotating the fixing roller 44 to rotate the fixing belt 44. The heating roller 47 and the pressure roller 52 are driven to rotate through 50, and the application roller 55 and the cleaning roller 56 are also driven to rotate.

  Then, the recording medium after the transfer image is formed is inserted into the fixing housing 40 from the inlet 41, guided by the inlet guide plate 58, guided to the fixing nip N, conveyed while being sandwiched between the fixing belt 50 and the pressure roller 52, and The fixing belt 50 and the pressure roller 52 apply heat and pressure to fix the unfixed toner image on the recording medium.

  By the way, in the present invention, a leveling device is provided in the middle of the recording medium conveyance path P, for example, in the paper feeding path P2 before the registration roller 23. Of course, the leveling device is not limited to the paper feed path P2, and may be provided in another recording medium transport path P. A leveling dedicated conveyance path may be provided, and a leveling device may be provided there.

FIG. 3 shows an example of the leveling device.
The illustrated leveling device 60 is provided with a square bar-shaped leveling member 61 facing the paper feed path P2. The leveling member 61 is disposed at a right angle to the conveyance direction D of the recording medium 62, and is normally retracted from the paper feed path P <b> 2 by the urging force of the tension spring 63. Although not shown, solenoid plungers are respectively connected to both ends of the leveling member 61. By energizing these solenoids, the leveling member 61 is placed in the paper feed path P2 against the tension spring 63. Can be projected.

  When the leading end of the recording medium 62 passing through the paper feed path P2 has just reached the leveling member 61 position of the leveling device 60, the conveyance of the recording medium 62 is temporarily stopped and the solenoid is energized. Is projected into the paper feed path P2 to press the tip of the recording medium 62, and the cutting burr 64 at the tip of the recording medium 62 is crushed and leveled. Since the cutting burrs 64 tend to be larger as the paper is thicker, the leveling member 61 is reciprocated up and down to increase the number of pressings as the paper becomes thicker.

FIG. 4 shows another example of the leveling device.
In the example shown in FIG. 4, the leveling member 61 is rotatably provided as a roller. By rotating the leveling member 61, the recording medium 62 is pressed while being conveyed, and the cutting burr 64 at the tip of the recording medium 62 is cut. Crush and push. The leveling member 61 reciprocates and appropriately continues forward and reverse plural times according to the thickness of the recording medium 62 and repeatedly presses the recording medium 62.

FIG. 5 shows still another example of the leveling device.
In the example shown in FIG. 5, the leveling member 61 is formed in a roller shape, and irregularities 66 are formed on the peripheral surface thereof, and are provided rotatably. In this way, even if the orientations are irregular or small in correspondence with various types of recording media 62, the cutting burr 64 is efficiently leveled, and the cutting burr 64 is cut. It is possible to prevent the image quality from being deteriorated.

  By the way, as the material of the roller-shaped leveling member 61, metal, resin, ceramics or the like is used. However, since the friction coefficient μ with the recording medium 62 can be increased, a rubber material is optimal. When the leveling member 61 is made of an elastic material, the leveling member 61 elastically presses the recording medium 62, and the leveling member 61 having a large friction coefficient μ presses the cutting burr 64 efficiently and effectively. It is possible to prevent the image quality from being deteriorated due to the cutting burr of the recording medium 62.

  In the example described above, the recording medium conveyance path P is provided obliquely from the lower right to the upper left in FIG. 1, and the drum-shaped image carriers 14Y, 14M, 14C, and 14B are provided along the recording medium conveyance path P. Then, the toner image formed on the image carrier is transferred to the recording medium 62, and the recording medium 62 after the image transfer is placed in the belt fixing device 24, and the unfixed toner image on the recording medium 62 is fixed to the recording medium 62. The case where the present invention is applied to an electrophotographic color printer has been described.

  However, the image forming apparatus according to the present invention is of course not limited to such an example. For example, the image carrier may be in the form of a belt, or the recording medium conveyance path may be provided horizontally. Needless to say, it is good. The present invention is not limited to an electrophotographic system, but is not limited to one provided with a belt fixing device. Of course, the present invention can be similarly applied not only to a printer but also to a copy or a facsimile.

1 is an overall schematic configuration diagram of an internal mechanism in an electrophotographic color printer according to the present invention. 1 is an overall schematic configuration diagram of a belt fixing device provided in the color printer. It is a schematic block diagram of an example of the leveling apparatus with which the color printer is equipped. It is a schematic block diagram of the other examples of a leveling apparatus. It is a schematic block diagram of the further another example of a leveling device. It is a principal part schematic block diagram of the conventional belt fixing apparatus. FIG.

Explanation of symbols

14Y / 14M / 14C / 14B Image carrier 24 Belt fixing device 60 Leveling device 61 Leveling member 62 Recording medium 64 Cutting burr 66 Unevenness P Recording medium conveyance path

Claims (6)

In an image forming apparatus for recording an image on a recording medium while conveying the recording medium,
An image forming apparatus, comprising: a leveling device that presses a recording medium with a leveling member and presses the cutting burr in a conveyance path of the recording medium.   The image forming apparatus according to claim 1, wherein the leveling member is formed in a roller shape, and the recording medium is pressed by rotation of the leveling member.   The image forming apparatus according to claim 2, wherein unevenness is formed on a peripheral surface of the leveling member.   The image forming apparatus according to claim 1, wherein the leveling member is made of an elastic material.   The image forming apparatus according to claim 1, wherein the leveling member is reciprocated to repeatedly press the recording medium.   The toner image formed on the image carrier is transferred to a recording medium, the recording medium after the image transfer is placed in a belt fixing device, and the unfixed toner image on the recording medium is fixed to the recording medium. The image forming apparatus according to claim 1.

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