JP6387716B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus.

  Patent Document 1 discloses that toner is supplied to a photoconductor on the upstream side of a cleaning blade for cleaning the photoconductor.

  In Patent Document 2, in a configuration including a cleaning blade for cleaning a photoconductor, abrasive particles are supplied to the photoconductor on the upstream side of the cleaning blade in order to prevent an image flow in an initial period of 1 to 1000 sheets. It is disclosed.

JP 2009-229727 A JP 2009-069772 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus that prevents an increase in load on a cleaning blade, which is a problem particularly with a small particle size toner.

Claim 1 is a photoconductor on which a toner image is formed through rotation, charging, exposure and development;
A transfer device for transferring the toner image onto a sheet;
A fixing device for fixing the toner image transferred on the paper onto the paper;
A cleaning blade in contact with a region of the photoconductor after the toner image is transferred, blocking residual toner on the photoconductor, and scraping off the photoconductor;
A dam that prevents the residual toner from being scraped by forming a dam sandwiched between the photosensitive member and the cleaning blade in a region after transfer of the toner image on the upstream side of the cleaning blade. A dam formation body supply device for supplying the formation body,
The dam forming body supply device is a dam forming body made of oil silica which is silica containing oil, and has a relatively large average particle diameter and relatively spherical oil silica, and a relatively small average An image forming apparatus characterized by supplying a dam forming body having a particle size and a relatively amorphous oil silica .

According to a second aspect of the present invention, the dam forming body supply device supplies more dam forming bodies as the image density is smaller in accordance with the image density of the toner image formed on the photoconductor. the image forming apparatus according to claim 1 Symbol mounting to.

Claim 3, the volume average particle size of the toner used for the development, an image forming apparatus according to claim 1 Symbol mounting, characterized in that at 4.5μm or less.

According to a fourth aspect of the present invention, there is provided a photoreceptor on which a toner image is formed through rotation, charging, exposure, and development, a transfer device that transfers the toner image onto a sheet, and the toner image transferred onto the sheet. Adopted in an image forming apparatus provided with a fixing device for fixing on top and a cleaning blade that contacts a region of the photoconductor after the toner image is transferred, blocks the residual toner on the photoconductor, and scrapes off the photoconductor. And
A dam that prevents the residual toner from being scraped by forming a dam sandwiched between the photosensitive member and the cleaning blade in a region after transfer of the toner image on the upstream side of the cleaning blade. A dam forming body supply device for supplying a forming body,
The dam forming body is a dam forming body made of oil silica, which is silica containing oil, and has a relatively large average particle diameter and relatively spherical oil silica, and a relatively small average particle diameter. The dam forming body supply device is characterized in that it is a dam forming body containing relatively irregular oil silica .

According to the image forming apparatus of the first aspect and the dam forming body supply apparatus of the fourth aspect , a strong dam is formed at the position of the cleaning blade.

Further, according to the dam forming material feeding apparatus of an image forming apparatus and claim 4 of claim 1, the material of the external additive of the same type as the toner, shortage of the external additive is compensated.

According to claim 2 the image forming apparatus, regardless of the image density of the toner image, always be sufficient dams are formed.

The present invention, as described in claim 3, the volume average particle diameter is less robust dam even when the toner having a small particle size is employed 4.5μm is formed.

1 is an external perspective view of an image forming apparatus as an embodiment of the present invention. FIG. 2 is a schematic diagram showing an internal configuration of the image forming apparatus whose appearance is shown in FIG. 1. It is a schematic diagram showing the powder supply apparatus and its periphery.

  Embodiments of the present invention will be described below.

  FIG. 1 is an external perspective view of an image forming apparatus as an embodiment of the present invention.

  The image forming apparatus 1 includes a scanner 10 and a printer 20.

  The scanner 10 is an apparatus that reads an image drawn on a document and generates an image signal. The printer 20 is a device that prints out an image based on an image signal on paper.

  The scanner 10 includes a document tray 11 and a document discharge tray 12. When the start button 32 is pressed with the documents stacked on the document tray 11, the documents are sequentially fed and read one by one and discharged onto the document discharge tray 12. Further, the scanner 10 is provided with a hinge (not shown) extending left and right on the back side, and can lift and open a portion above the arrow M. A transparent glass plate 13 (see FIG. 2) extends just below the arrow M. It is also possible to read the original on the transparent glass plate 13 by placing one original on the transparent glass plate 13 downward, closing the upper part from the arrow M and pressing the start button 32.

  The printer 20 is a device that sequentially takes out the sheets stacked in the paper tray 21 one by one and prints an image based on the image signal on the taken-out paper. The paper on which the image is printed is discharged onto the paper discharge tray 22. In the present embodiment, the printer 20 is a printer that prints out an image on paper by a so-called electrophotographic method.

  In addition, the image forming apparatus 1 includes a user interface (UI) 30. The UI 30 includes a power button 31, a start button 32, a plurality of other push buttons 33, and a touch panel display screen 34. By operating the UI 30, various instructions such as an instruction for the number of prints and an instruction for starting an operation are performed. The display screen 34 displays the state of the apparatus and various push buttons. The push button 34 displayed on the display screen 34 is also an operation target.

  FIG. 2 is a schematic diagram showing the internal configuration of the image forming apparatus whose appearance is shown in FIG.

  The documents S placed on the document tray 11 of the scanner 10 are fed one by one when the start button 32 (see FIG. 1) is pressed, and are conveyed on the conveyance path 101 by the conveyance roll 14, and in the middle of the conveyance. The paper passes through a reading position R in contact with the transparent glass plate 13 and is discharged onto the document discharge tray 12. Then, when the document S passes through the reading position R, the image recorded on the document S is read and converted into an image signal by the reading device 15 that is stationary while facing the reading position R. Is done.

  Further, the part above the arrow M is opened, and one original is placed downward on the transparent glass plate 13 to close the top, and the start button 32 is pressed. Then, this time, the reading device 15 reads the document on the transparent glass plate 13 while moving in the arrow X direction, and converts it into an image signal.

  In addition, the printer 20 includes four image forming units 50Y, 50M, 50C, and 50K that are arranged in a row substantially horizontally. In these image forming units 50Y, 50M, 50C, and 50K, toner images are formed using toners of yellow (Y), magenta (M), cyan (C), and black (K), respectively. Here, for the description common to these image forming units 50Y, 50M, 50C, and 50K, the reference numerals Y, M, C, and K representing the distinction of the toner colors are omitted, and are denoted as the image forming unit 50. . The same applies to other components other than the image forming unit.

  Each image forming unit 50 includes a photoreceptor 51. The photosensitive member 51 receives a driving force and rotates in the direction of arrow A to form an electrostatic latent image on the surface thereof, and further, a toner image is formed by development.

  Around each photoconductor 51 provided in each image forming unit 50, a charger 52, an exposure device 53, a developing device 54, a primary transfer device 62, a powder supply device 55, and a photoconductor cleaner 56 are provided. It has been. Here, the primary transfer unit 62 is placed between the photoreceptor 51 and an intermediate transfer belt 61 described later. The primary transfer device 62 is an element provided not in the image forming unit 50 but in an intermediate transfer unit 60 described later.

  The charger 52 uniformly charges the surface of the photoreceptor 51.

  The exposure device 53 irradiates the uniformly charged photoconductor 51 with exposure light modulated based on the image signal, thereby forming an electrostatic latent image on the photoconductor 51.

  The developing device 54 develops the electrostatic latent image formed on the photoconductor 51 with toner of a color corresponding to each of the image forming units 50Y, 50M, 50C, and 50K, and forms a toner image on the photoconductor 51. To do.

  The primary transfer unit 62 transfers the toner image formed on the photoreceptor 51 onto an intermediate transfer belt 61 described later.

  The powder supply device 55 supplies the oil silica to the upstream side of the cleaning blade 561 in the region after the toner image transfer of the photoreceptor 51. The powder supply device 55 corresponds to an example of a dam forming body supply device in the present invention. Details of the powder supply device 55 will be described later.

  The photoconductor cleaner 56 is provided with a cleaning blade 561 that is pressed against the photoconductor 51 and blocks and removes residual toner adhering to the photoconductor 51 after transfer from the photoconductor 51.

  An intermediate transfer unit 60 is disposed above the four image forming units 50. The intermediate transfer unit 60 is provided with an intermediate transfer belt 61. The intermediate transfer belt 61 is supported by a plurality of rolls such as a drive roll 63a, a driven roll 63b, and a tension roll 63c. Then, the intermediate transfer belt 61 is driven by a driving roll 63a, and an arrow moves on a circulation path including a path along the four photosensitive members 51 provided in the four image forming units 50Y, 50M, 50C, and 50K. Circulately moves in the B direction.

  The toner images on the respective photoreceptors 51 are transferred so as to sequentially overlap the intermediate transfer belt 61 by the action of the primary transfer unit 62. The toner image transferred onto the intermediate transfer belt 61 is conveyed to the secondary transfer position T2 by the intermediate transfer belt 61. The secondary transfer position T2 is provided with a secondary transfer unit 71, and the toner image on the intermediate transfer belt 61 has been conveyed to the secondary transfer position T2 by the action of the secondary transfer unit 71. Transferred onto the paper P. The conveyance of the paper P will be described later. The toner remaining on the intermediate transfer belt 61 after the transfer of the toner image onto the paper P is removed from the intermediate transfer belt 61 by the intermediate transfer belt cleaner 64.

  Here, in the printer 20, a black and white (K) toner is used to form a toner image, and a monochrome image is formed on the paper P only by the image forming unit 50K located at one end (the leftmost end in FIG. 2) of the array. It has a monochrome mode for printing an image and a color mode for printing a color image on paper P using four image forming units 50Y, 50M, 50C, and 50K. The intermediate transfer belt 61 is moved in contact with the four photosensitive members 51 constituting the four image forming units 50Y, 50M, 50C, and 50K in the color mode by a cam mechanism (not shown), and in the monochrome mode, Photoconductors 51Y, 51M, and 51C of all other image forming units 50Y, 50M, and 50C are in contact with only the photoconductor 51K of the image forming unit 50K located at one end of the array (the leftmost end in FIG. 2). The circulation movement route is changed so as to be separated from. In the monochrome mode, the operations of all the image forming units 50Y, 50M, and 50C other than the image forming unit 50K are stopped to save power and extend the life of parts.

  A toner cartridge 23 that contains toner of each color is provided on the upper portion of the intermediate transfer unit 60. When the toner in the developing device 54 is consumed by development, the toner is replenished to the developing device 54 from the toner cartridge 23 containing the corresponding color toner. The toner cartridge 23 is configured to be detachable. When the toner cartridge 23 is empty, the toner cartridge 23 is removed and a new toner cartridge 23 is mounted.

  A paper tray 21 is provided at the bottom of the printer 20. In the paper tray 21, the sheets P before printing are stored in a stacked state. The paper tray 21 is configured to be drawn out for replenishment and replacement of paper.

  One sheet P is taken out from the paper tray 21 by the pickup roll 211, and is conveyed by the conveyance roll 23 to the timing adjustment roll 24 in the direction of arrow C on the conveyance path 201. The sheet P conveyed to the timing adjustment roll 24 reaches the secondary transfer position T2 in accordance with the timing at which the toner image on the intermediate transfer belt 61 reaches the secondary transfer position T2 by the timing adjustment roll 24. Thus, the sheet is fed toward the secondary transfer position. The sheet P sent out by the timing adjustment roll 24 receives the toner image transferred from the intermediate transfer belt 61 by the action of the secondary transfer unit 71 at the secondary transfer position T2. The sheet P that has received the transfer of the toner image is further conveyed in the direction of arrow D and passes through the fixing device 72. The toner image on the paper P is fixed on the paper P by being heated and pressurized by the fixing device 72. As a result, an image composed of the fixed toner image is printed on the paper P. The sheet on which the toner image has been fixed by the fixing device 72 is further conveyed by the conveying roll 25, and sent out from the sheet discharge outlet 27 onto the sheet discharge tray 22 by the sheet discharge roll 26.

  Further, the printer 20 has a double-sided print mode for printing images on both sides of the paper P. In this double-sided print mode, after the image is printed on the first side of the paper P in the same manner as described above, the paper P on which the image is printed on the first side is discharged by the paper discharge roll 26 by the paper discharge tray 22. It is sent out halfway toward. Then, the paper discharge roll 26 reverses the rotation direction and pulls back the paper P that has been fed halfway onto the paper discharge tray 22.

  The paper P that has been pulled back by the reversal of the paper discharge roll 26 is now transported by the transport roll 27 in the direction indicated by the arrow G on the transport path 202 and reaches the timing adjustment roll 24 again. At this time, the paper P is in a state where the front and back are reversed from when the image is printed on the first surface. After reaching the timing adjustment roll 24 again, the image is printed on the second side of the paper P in the same manner as described above. The paper P on which images are printed on both sides in this manner is sent out onto the paper discharge tray 22 by the paper discharge roll 26 this time.

  The printer 20 is provided with a manual feed tray 28. When a sheet is placed on the manual feed tray 28 and the start button 32 is pressed, the paper on the manual feed tray 28 is conveyed on the conveyance path 203 in the direction of arrow H by the conveyance roll 29 and reaches the timing adjustment roll 24. The subsequent printing operation is the same as the printing operation on the paper P drawn from the paper tray 21.

  Further, the image forming apparatus 1 is provided with a control circuit 40 that controls each unit, and the operation is controlled by the control circuit 40. The control circuit 40 is an example of both a determination unit and a control unit in the present invention.

  Next, the powder supply device 55 that is a feature of the present embodiment will be described.

  FIG. 3 is a schematic diagram showing the powder supply apparatus and its surroundings.

  Since FIG. 3 is common to the four image forming units 50, Y, M, C, and K symbols representing colors are omitted here.

  The photoconductor 51 rotates in the direction of arrow A (see also FIG. 2).

  A toner image is formed on the photoreceptor 51 on the upstream side in the rotational direction from the portion shown in FIG. 3, and the toner image is formed on the intermediate transfer belt 61 by the action of the primary transfer unit 62 (see FIG. 2). Is transcribed. Then, the toner 80 remaining on the photoconductor 51 after the transfer reaches the photoconductor 51. The toner 80 includes toner particles 81 and external additives such as oil silica 82 having a smaller diameter than the toner particles 81.

  The powder supply device 55 is a device that supplies the oil silica 551 to the upstream side of the cleaning blade in the region after the toner transfer of the photosensitive member 51. In the present embodiment, the powder supply device 55 supplies the same type of oil silica 551 as the oil silica 82 in the external additive contained in the toner 80. The oil silica 551 is a powder having a particle size distribution extending over a wide range of 50 nm to 500 nm. The oil silica 551 is a mixture of spherical oil silica 551a having a relatively large average primary particle diameter and amorphous oil silica 551b having a relatively small average primary particle diameter. The average primary particle size of the spherical oil silica 551a varies depending on the specific material of the oil silica 551, the particle size of the toner particles 81, the surface property of the photoreceptor 51, the material of the cleaning blade 561, and the like. Within range. Moreover, the average primary particle diameter (particle diameter when it is regarded as the spherical shape of the same volume) of the irregular-shaped oil silica 551b is in the range of 40 nm to 100 nm, for example. Here, spherical oil silica having a shape factor SF1 of 125 or less is preferably used. In addition, amorphous oil silica having a shape factor SF1 of 130 or more is preferably used. Further, the weight ratio of the spherical silica to the amorphous silica is preferably in the range of 1: 5 to 5: 1. In this embodiment, the toner particles 81 constituting the toner 80 have a particle size larger than that of the oil silica 551 supplied by the powder supply device 55, but those having a diameter of 4.5 μm or smaller are employed. . In this embodiment, a dimethylsilicone oil-treated silica (average primary particle size 120 nm) having a shape factor SF1 of 115 and a dimethylsilicone oil-treated silica (average primary particle size 50 nm) having a shape factor SF1 of 135 are used in a weight ratio of 1: 3. Used in.

  The cleaning blade 561 is made of a rubber-based material, and is rubbed with the photoconductor 51 due to the rotation of the photoconductor 51 in the direction of arrow A, and dragged by the photoconductor 51. As schematically shown in FIG. Deform. Here, the oil silica 551 supplied by the powder supply device 551 enters the gap between the photoconductor 51 and the cleaning blade 561 as the photoconductor 51 rotates. Since the oil silica 551b has a small particle diameter, as shown in FIG. 3, the oil silica 551b is likely to enter the tip portion in the rotation direction (arrow A direction) of the photoconductor 51 between the photoconductor 51 and the cleaning blade 561. Since the oil silica 551b is indefinite, the oil silica 551b interferes with each other to form a strong block, and the amount of abrasion between the photoconductor 51 and the cleaning blade 561 is moderately small. Can be suppressed. Further, since the spherical oil silica 551a has a relatively large particle size, the gap between the photoconductor 51 and the cleaning blade 561 is relatively open at the rear of the arrow A in the direction of the irregular oil silica 551b. Easy to accumulate. Since the oil silica 551a is spherical, it has a close packing structure close to the closest packing structure. Since the toner particles 81 have a larger particle size, they tend to accumulate further in the rearward direction in the direction of the arrow A, and are blocked by the oil silica 551 without rubbing through the dam structure. The blocked toner particles 81 spill from the photoreceptor 51 and are carried to a waste toner box (not shown) by a waste toner collecting mechanism (not shown). In the present embodiment, the oil silica 551 (including the oil silica 82 in the external additive of the toner 80) in the entire dam structure 57 including the toner particles 81 is 0.25 to 0.35% by weight. Have been adjusted. In this adjustment, the supply port 55a of the powder supply device 55 is opened for a time corresponding to the image density of the toner image formed by the image forming unit 50 (see FIG. 2), or the supply port 55a is opened. This is done by adjusting the opening area according to the image density. In particular, when the image density of the toner image is low, the amount of the toner 80 is originally small, so that the oil silica 82 supplied from the toner 80 is insufficient. Therefore, when the image density of the toner image is low, the time or the opening area is controlled so that more oil silica 551 is supplied from the powder supply device 55.

  The toner 80 used in the image forming apparatus 1 is a toner that employs toner particles 81 having a small particle diameter of 4.5 μm or less in volume average particle diameter. Employing such a small particle size can reduce the amount of toner consumed in forming an image with the same density. However, if the toner consumption is reduced, the amount of the external additive of the toner decreases accordingly, and there is a possibility that the oil silica sufficient to form the sufficient dam 57 cannot be supplied with the toner alone. In the case of this embodiment, since the shortage of oil silica is compensated for by the powder supply device 55, an amount of oil silica sufficient for the formation of the dam is supplied. In the case of the present embodiment, the powder supply device 55 supplies oil silica 551 composed of a mixture of spherical oil silica 551a having a relatively large particle diameter and amorphous oil silica 551b having a relatively small particle diameter. As described above, a strong dam is formed, and the toner is reliably blocked and collected. The toner particles have a volume average particle diameter of 2 μm or more from the viewpoint of manufacturability.

  Here, the powder supply device 55 is described as compensating for the shortage of the oil silica 82 in the toner 80. Here, the external additive in the toner 80 plays a role other than dam formation, such as preventing aggregation of the toner particles 81 and adjusting the fluidity of the toner 80. Therefore, the external additive of the toner 80 has a role other than the dam formation, and the dam formation has a role so that the particles such as the oil silica 551 supplied by the powder supply device 55 are assigned. You may let them. Then, the degree of freedom in designing the toner and the powder supplied by the powder supply device 55 is improved. In this case, the powder for dam formation supplied by the powder supply device 55 may be oil silica specialized for dam formation, which is different from the oil silica 82 in the toner 80. Or the powder suitable for dam formation other than oil silica may be sufficient, and the mixture of such powder and oil silica may be sufficient.

  Here, the example in which the powder supply device 55 is applied to the type of image forming apparatus shown in FIGS. 1 and 2 has been described. However, the image forming apparatus of the present invention forms a toner image on the photosensitive member and remains. Any toner may be used as long as the toner is blocked by a blade-shaped cleaning member, and the present invention can be applied to a wide variety of image forming apparatuses.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 10 Scanner 20 Printer 40 Control circuit 50 Image forming part 51 Photoconductor 52 Charger 53 Exposure unit 54 Developer 55 Powder supply apparatus 55a Supply port 56 Photoconductor cleaner 57 Dam 60 Intermediate transfer part 61 Intermediate transfer belt 62 Primary transfer device 71 Secondary transfer device 72 Fixing device 80 Toner 81 Toner particle 82,551 Oil silica 551a Spherical oil silica 551b Indeterminate oil silica 561 Cleaning blade

Claims (4)

A photoreceptor on which a toner image is formed through rotation, charging, exposure and development;
A transfer device for transferring the toner image onto a sheet;
A fixing device for fixing the toner image transferred on the paper onto the paper;
A cleaning blade in contact with a region of the photoconductor after the toner image is transferred, blocking residual toner on the photoconductor, and scraping off the photoconductor;
A dam that prevents the residual toner from being scraped by forming a dam sandwiched between the photosensitive member and the cleaning blade in a region after transfer of the toner image on the upstream side of the cleaning blade. A dam formation body supply device for supplying the formation body,
The dam forming body supply device is a dam forming body made of oil silica which is silica containing oil, and has a relatively large average particle diameter and relatively spherical oil silica, and a relatively small average An image forming apparatus for supplying a dam forming body having a particle size and a relatively amorphous oil silica . 2. The dam forming body supply device supplies more dam forming bodies as the image density is smaller in accordance with the image density of a toner image formed on the photosensitive member. Image forming apparatus. The volume average particle size of the toner used for development is, claim 1 Symbol placing the image forming apparatus is characterized in that at 4.5μm or less. A photosensitive member that forms a toner image through rotation, charging, exposure, and development, a transfer device that transfers the toner image onto a sheet, and a fixing that fixes the toner image transferred onto the sheet onto the sheet And an image forming apparatus provided with a cleaning blade that contacts a region of the photoconductor after the toner image is transferred, blocks residual toner on the photoconductor, and scrapes off the photoconductor.
A dam that prevents the residual toner from being scraped by forming a dam sandwiched between the photosensitive member and the cleaning blade in a region after transfer of the toner image on the upstream side of the cleaning blade. A dam forming body supply device for supplying a forming body,
The dam forming body is a dam forming body made of oil silica, which is silica containing oil, and has a relatively large average particle diameter and relatively spherical oil silica, and a relatively small average particle diameter. A dam forming body supply device , characterized in that the dam forming body includes a relatively amorphous oil silica .

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