JP2007072236A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus in which banding is not conspicuous, with small misalignment and color shift, which can be down sized and manufactured at a low cost. <P>SOLUTION: The image forming apparatus is provided with a cylindrical image carrier carrying an electrostatic latent image, a developing apparatus with a developing roller developing the electrostatic latent image, a first drive transmitting means driving the image carrier and a second drive transmitting means driving the developing apparatus from one driving source. The first drive transmitting means is provided with a large diameter gear 39 to which transmission is made from the driving source in a direct one step speed reduction and with a greater outer diameter than an outer diameter of the image carrier. The second drive transmitting means is composed of friction transmitting means (40, 43 and 47). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile, or a complex machine thereof, and more particularly, forms a toner image by an electrophotographic process such as charging, optical writing, development, transfer, and cleaning, and forms a paper / card The present invention relates to an electrophotographic image forming apparatus that records on a recording medium such as an OHP sheet.

  In an electrophotographic image forming apparatus using an electrophotographic image forming process, a developer is attached to an electrostatic latent image formed on the surface of an image carrier by a developing device, and the formed toner image is transferred to a transfer material. . These image carrier and developing device are configured such that a rotational driving force is transmitted from a driving source via a driving gear train or a belt. That is, the photosensitive drum and the developing means are driven to rotate from a single drive source via separate drive gear trains (see, for example, Patent Document 1), or via an idler gear train that meshes with the image carrier drive gear. A flat belt is hung on a driven pulley that rotates integrally with a photosensitive pulley and a driving pulley that is supplied with a rotational force from a motor and that that rotates the developing roller by transmitting to the developing gear (see, for example, Patent Document 2). In some cases, the photosensitive drum is driven to rotate (see, for example, Patent Document 3).

  As described above, in the configuration in which the conventional image carrier and the developing device are rotationally driven from the drive source via the drive gear train, the meshing vibration of the gear propagates to the image carrier and uneven rotation of the meshing frequency occurs. This causes image deterioration such as striped unevenness, so-called banding. Since the image carrier forms a toner image on the surface thereof, if uneven rotation occurs in the image carrier, it causes direct image degradation. Further, in the developing device, uneven rotation or vibration of the developing roller propagates through the developing device, or vibration of the developing device itself propagates to a member supporting the image carrier, thereby inducing uneven rotation of the image carrier. Causes image degradation. Particularly in a two-component developing device, the load increases because the toner and the carrier are agitated with a screw, or the developer mixed with the toner and the carrier is pumped up by a developing roller, and then clogged with a doctor blade to make it thin. At the same time, pulsation of the developer occurs, causing vibration. As a method of improving this problem, there is a method of improving the gear tooth profile accuracy, but this increases the cost. Even if the tooth profile accuracy is improved, if a load change occurs in the image carrier and the developing roller, the backlash vibration of the gear is generated, resulting in banding. In particular, in a two-component developing device, load fluctuation due to pulsation is likely to occur, which causes banding.

  In Patent Document 1, the photosensitive drum and the developing unit are driven by a single drive motor to reduce cost and size, but banding due to gear meshing vibration is inevitable. The same applies to Patent Document 2. As means for solving these problems, there is a configuration of friction transmission drive by a flat belt or a friction roller which is not gear meshing drive transmission. However, although the generation of banding can be prevented by driving a flat belt or a friction roller, since driving is performed using frictional force, slippage may occur in drive transmission when a large load is applied to the image carrier. Due to the slippage of the drive transmission, rotation unevenness occurs in the image carrier and an image position shift occurs. Further, a color image forming apparatus has a problem of color misregistration. In Patent Document 3, since the image carrier is driven by a flat belt, image deterioration due to banding can be prevented, but slippage occurs, and image positional deviation and color deviation are unavoidable.

JP 2001-147568 A Japanese Patent No. 3599632 JP 7-36346 A

  Accordingly, the present invention solves the problems of the conventional ones, and in an image forming apparatus having a configuration for driving an image carrier and a developing device, banding is not conspicuous, positional displacement and color misregistration are small, and compact and low cost. An object is to provide a possible image forming apparatus.

  In order to solve the above-mentioned problems, a first aspect of the present invention provides a cylindrical image carrier for carrying an electrostatic latent image, a developing device having a developing roller for developing the electrostatic latent image, and one In an image forming apparatus comprising a first drive transmission means for driving an image carrier from a drive source and a second drive transmission means for driving a developing device, the first drive transmission means is directly connected to the first stage from the drive source. It has a large-diameter gear that is transmitted at a reduced speed and has an outer diameter larger than the outer diameter of the image carrier, and the second drive transmission means is constituted by a friction transmission means.

  According to a second aspect of the present invention, in the first aspect, when the number of teeth of the large-diameter gear of the first drive transmission means is Zd and the diameter of the image carrier is Dd (mm), Zd / π × Dd> 2. The conditions are set so that A third aspect of the present invention provides the image forming apparatus according to the first aspect, wherein the surface linear velocity of the image carrier is Vd (mm / sec) and the developing roller surface linear velocity of the developing device is Vg (mm / sec). Conditions are set so that Vd> 1.2.

  According to a fourth aspect of the present invention, in any one of the first to third aspects, the friction transmission means includes a transmission pulley provided coaxially with the large-diameter gear of the first drive transmission means, a developing roller of the developing device, The development transmission pulley is provided coaxially and a toothless transmission belt that connects both pulleys by frictional force. According to a fifth aspect of the present invention, in any one of the first to third aspects, the friction transmission means includes a friction drive pulley provided coaxially with the large-diameter gear of the first drive transmission means, and a developing roller of the developing device. And a developing friction pulley that is driven and transmitted in frictional contact with the friction drive pulley.

  According to a sixth aspect of the present invention, in the fourth aspect, the drive source, the first drive transmission means, and the second drive transmission means are provided on the main body apparatus side, and the developing device is detachable from the apparatus main body. And friction connecting means for connecting the second drive transmission means and the developing device. According to a seventh aspect of the present invention, in the fifth aspect, the drive source, the first drive transmission means, and the second drive transmission means are provided on the main body side, and the developing device is detachable from the main body. And friction connecting means for connecting the second drive transmission means and the developing device.

  According to an eighth aspect of the present invention, in the sixth or seventh aspect, the frictional coupling means is a coupling. The invention according to claim 9 is the invention according to claim 8, wherein the coupling is a convex and concave taper fitting, and the fitting surface is made of a high friction material.

  According to a tenth aspect of the present invention, in the fourth or fifth aspect, the developing device includes a developing roller and a screw that stirs the developer, and each of the screw and the developing roller has a toothless transmission pulley. It is configured to be linked and interlocked by a transmission belt.

  The present invention is as described above, wherein the first drive transmission means has a large-diameter gear which is directly transmitted from the drive source at a one-step reduction and has an outer diameter larger than the outer diameter of the image carrier. Since the second drive transmission means is constituted by friction transmission means, the image carrier is in gear-engaged drive transmission, and it is possible to prevent positional deviation and color deviation due to slipping. In addition, since it is driven by a large-diameter gear whose outer diameter is larger than the outer diameter of the image carrier, the outer diameter of the image carrier and the pitch circle diameter of the gear on the image carrier even if vibration of the frequency occurs due to meshing. The ratio becomes smaller and becomes less noticeable as banding. Further, since the developing device is driven by friction transmission, vibration due to meshing does not occur, and therefore, the image quality of banding does not deteriorate. Friction transmission drive is feared to cause slippage, but in the two-component developing device, the developing roller and the image carrier are not in contact with each other, so even if slight slippage occurs in the drive transmission system, the image carrier is not rotated. It does not affect. Further, since there is only one drive source, it is possible to expect an excellent effect that the size and cost are reduced.

  Embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 is a schematic configuration diagram of an entire color electrophotographic recording apparatus shown as an example of an image forming apparatus. A plurality of photosensitive drums 1C, 1Y, 1M, 1BK as a plurality of image carriers are arranged in parallel in the horizontal direction. Around each photosensitive drum, a charging roller 2, a developing device 3, a cleaning device 4, and a charge eliminating lamp 5 are disposed. In FIG. 1, reference numerals are given only to the charging rollers 2C around the photosensitive drum 1C, and the other photosensitive drums are omitted. A writing device 6 is disposed above the photosensitive drums 1C, 1Y, 1M, and 1BK. The writing device 6 may be either LD or LED. An intermediate transfer belt 7 serving as an intermediate transfer material is in contact with the photosensitive drums 1C, 1Y, 1M, and 1BK, and is stretched by three support rollers 10, 11, and 12 below each photosensitive drum. Yes. For example, three or more supporting rollers may be stretched such as a roller for adjusting the belt deviation. A primary transfer roller 13 is pressed against the photosensitive drums 1C, 1Y, 1M, and 1BK via an intermediate transfer belt 7. Although an example of a roller is shown here, a non-contact charger may be used. A belt cleaning device 15 is provided on the intermediate transfer belt 7 at a position facing the support roller 10. A counter roller may be provided separately for the position of the belt cleaning device 15, and a belt cleaning device may be provided.

  One of the rollers supporting the intermediate transfer belt 7 and the support roller 12 have a function of a counter roller of the secondary transfer unit, and a secondary transfer belt 16 as a secondary transfer unit is disposed at the opposing position. It is stretched by two support rollers. In addition, a secondary transfer roller or a charger may be provided as the secondary transfer unit. Although not shown, the secondary transfer belt 16 is provided with a cleaning device. The secondary transfer belt 16 is disposed so that the transfer material can be conveyed to the entrance of the fixing device 17. The fixing device 17 includes an endless fixing belt 18, two rollers that support the fixing belt 18, and a pressure roller 19 that is in pressure contact with the fixing belt. The fixing device 17 is disposed below the support roller 10 of the intermediate transfer belt 7 so as to enter the opposing roller side of the secondary transfer. Under the fixing device 17 and the intermediate transfer belt 7, a double-side reversing device 21 for double-sided transfer is disposed in the horizontal direction. The double-side reversing device 21 includes a reversing roller 22, a sending roller 23, and a plurality of conveying roller pairs 24. In FIG. 1, 25 is an ADF, 26 is a scanner, and 27 is a paper bank.

  A series of operations of the color electrophotographic recording apparatus will be described. When copying a manuscript. A document is sent from the ADF tray 28 to the contact glass surface to the ADF 25 and read by the scanner 26. The data is transmitted to the writing device 6, and the photosensitive drums 1 </ b> C, 1 </ b> Y, 1 </ b> M, 1 </ b> BK charged by the charging roller 2 are exposed based on the image data read by the writing device 6 to form an electrostatic latent image. . The photosensitive drum rotates in the direction of the arrow, and the electrostatic latent image is developed into a visible image by the developing device 3. A visible image of a different color is developed on each photoconductive drum, and the photoconductive drums 1 </ b> C to 1 </ b> BK are sequentially primary-transferred onto the intermediate transfer belt 7.

  On the other hand, the transfer material is fed from the paper bank 27 to the registration roller 31 and stopped and stands by. The transfer material is sent from the registration roller 31 in accordance with the timing at which the primary transfer image superimposed on the intermediate transfer belt 7 is conveyed, and the primary transfer image is transferred in batch at the secondary transfer portion. Secondary transferred onto the material. The transfer material subjected to the secondary transfer is conveyed as it is to the fixing device 17 by the secondary transfer belt 16 and enters the fixing device 17. When the transfer material fixed by the fixing device 17 is discharged as it is and stacked on the discharge tray 32 or is copied on both sides, it is conveyed to the lower side after fixing and once sent to the stack portion of the double-side reversing device 21. It is. Then, the transfer material is sent from the rear end of the transfer material to the reverse roller 22 by the feed roller 23, and the transfer material is U-turned and conveyed to the registration roller 31 by a plurality of conveyance roller pairs 24. The subsequent steps are the same as for the surface copy.

  In the recording apparatus as described above, the photosensitive drums 1C, 1Y, 1M, and 1BK are one-stage from the motor gear 37 of the driving motor 36 that is a driving source, as shown in FIG. 2 which is the photosensitive drum 1C. The drive is transmitted to the photosensitive drum gear 39 fixed to the shaft 38 of the photosensitive drum 1C at a reduced speed so as to rotate. Further, a transmission pulley 40 is provided for transmitting the drive to the developing device 3C coaxially with the photosensitive drum gear 39. The photosensitive drum shaft 38 to which the photosensitive drum gear 39 and the transmission pulley 40 are fixed is rotatably supported by the main body side plate 42. In the embodiment, the photosensitive drum shaft 38 is directly fixed to the photosensitive drum 1C. However, the photosensitive drum shaft 38, the photosensitive drum gear 39, and the transmission pulley 40 are connected via a coupling. It is good also as a structure. In the developing device 3C, a development transmission pulley 43 rotatably supported on the main body side plate 42 is connected to a shaft 45 of the developing roller 44 via a development driving coupling 46 as a frictional connection means. The transmission pulley 40 and the development transmission pulley 43 are connected by a transmission belt 47 so that the driving rotation of the photosensitive drum 1C is transmitted to the developing roller 44 of the developing device 3C.

  FIG. 3 shows the drive transmission system from the drive motor 36 to the motor gear 37, the photosensitive drum gear 39, the transmission pulley 40, the transmission belt 47, and the development transmission pulley 43, and the photosensitive drum 1C. The transmission belt 47 is wound around the outer surface of the belt around the transmission pulley 40 provided coaxially with the photosensitive drum gear 39, and is wound around the inner surface of the belt around the development transmission pulley 43 to rotate the photosensitive drum 1C. This is transmitted to the developing roller 44 of the developing device 3C. The transmission belt 47 secures a winding angle around the transmission pulley 40 by two winding pulleys 50 and 51 provided near the surface of the transmission pulley 40. Either one of the winding pulleys 50 and 51 is pulled or compressed by an elastic member such as a spring (not shown) in order to apply tension to the transmission belt 47. With such a configuration, the developing device 3C is connected to the developing belt 3C. Drive rotation is more stable.

  By winding the transmission belt 47 in this way, the rotation directions of the photosensitive drum 1C and the developing roller 44 can be made opposite to each other, and the traveling directions of the respective facing surfaces can be made the same direction. In the case where the surface traveling directions of the photosensitive drum 1C and the developing roller 44 are opposite to each other, the configuration shown in FIG. That is, according to this modification, the transmission pulley 40 and the development transmission pulley 43 are wound around the inner surface of the transmission belt 53 and are frictionally transmitted, and the tension pulley 54 that applies tension to the transmission belt 53 is directed from the inside to the outside. It is pressurized by an elastic member such as a spring.

  The transmission belts 47 and 53 are constituted by flat belts, and the material is preferably a steel material, a resin material, particularly a polyimide material, or a rubber material, and among them, a type having a core wire to reduce elongation. In the case of a steel material or a resin material, it is desirable to coat the surface of the transmission belts 47 and 53 or the transmission pulley 40 and the development transmission pulley 43 with a high friction material made of rubber.

  The photosensitive drum 1C minimizes the gear meshing, which is a banding factor, by one-step reduction of the pinion of the motor gear 37 and the large-diameter gear of the photosensitive drum gear 39, and further reduces the outer diameter of the photosensitive drum gear 39 to the outer diameter of the photosensitive drum 1C. By increasing the ratio, the image on the photosensitive drum is reduced by the ratio of the gear diameter to the drum diameter even when gear meshing vibration occurs, and banding on the output image can be made inconspicuous. Further, because of the gear transmission, the rotation of the photosensitive drum 1C does not cause slippage, and does not cause a positional shift or a color shift. Even if there is an eccentricity in the gear, the color shift can be reduced by adjusting the eccentric phase of the photosensitive drum gear 39 of each color.

As shown in FIG. 3, when the outer diameter of the photosensitive drum 1C is Dd (mm) and the number of teeth of the photosensitive drum gear 39 is Zd,
Zd / π × Dd> 2 (1)
By satisfying this relationship, the banding of the output image can be made inconspicuous. The left side of equation (1) indicates the spatial frequency (cycle / mm) of the banding generated in the toner image formed on the surface of the photosensitive drum due to the rotational fluctuation caused by the gear meshing vibration when the photosensitive drum is driven. By setting 2 to 2 or more, banding can be made an area that cannot be perceived by human eyes.

  FIG. 5 shows the spatial frequency and perceptual sensitivity of the banding image. By setting the spatial frequency (cycle / mm) to an extremely low frequency or a high frequency, the banding can be made into an unperceivable region.

  In the embodiment, the developing device 3 is an example of a two-component developing device. That is, the developing device 3 includes a developing roller 44, a doctor blade 56, two screws 57 and 58, a toner density sensor 59, and an outer case 60 as shown in FIG. As for the positional relationship between the developing roller and the screw, the screws 57 and 58 are located obliquely below the developing roller 44, and the two screws are arranged in parallel in the horizontal direction. The outer case 60 is provided with a partition plate 61 that divides two screws into two chambers. The rear side and the front side of the partition plate 61 are cut out so that the developer can circulate between the two screws.

  Further, the outer case 60 has an opening at a portion facing the photosensitive drum 1C, and a part of the developing roller 44 is exposed from the opening. Thus, the outer case 60 surrounds the developing roller 44, the screws 57 and 58, and the doctor blade 56 with a little more space above the screw 57 beside the developing roller as shown in FIG. The developing roller 44 is configured by a nonmagnetic developing sleeve 44a that can rotate and a magnet 44b that is a magnetic field generating unit fixed inside. The developer is a two-component developer composed of a nonmagnetic toner and a magnetic carrier.

  The developer is conveyed while being agitated by the screws 57 and 58 whose feed directions are opposite to each other, and constantly circulates through the two chambers in the outer case 60. The developer that is circulated while being stirred and conveyed is supplied to the developing sleeve 44a by the screw 57, held on the surface in the form of a magnetic brush by the magnetic force of the magnet 44b, and pumped up in the rotating direction of the developing sleeve. The developer on the magnetic brush pumped up is trimmed to an appropriate amount by the doctor blade 56 and sent to the developing device facing the photosensitive drum 1C. The developer remaining after being cut off by the doctor blade 56 falls off the magnetic brush-like outside of the surface of the developing sleeve 44a by gravity, is returned to the screw 57, and is repeatedly supplied to the developing sleeve 44a while being stirred and conveyed again.

  On the other hand, the developer sent to the developing device 3 is visualized by the transfer of toner to the electrostatic latent image on the photosensitive drum 1C. The developer that has not been used for visualization returns to the inside of the outer case 60 and is separated from the developing sleeve 44a and collected by the screw 57 at a portion where the magnetic force of the magnet 44b does not work. Thus, the developer is supplied to the developing sleeve 44a and collected while being circulated through the screw 57 and the screw 58 while being stirred. Further, when the image is repeatedly output, the toner density becomes light. Therefore, toner is supplied (not shown) so that the density becomes constant while being detected by the toner density sensor 59.

  In such a two-component developing device 3, the developing roller 44 is not in contact with the photosensitive drum 1 </ b> C, and the developing roller linear velocity is made higher than the linear velocity of the photosensitive drum in order to improve the developing efficiency. In such a system, even if slight driving slip occurs, there is no influence, and meshing vibration such as gear drive transmission can be prevented by driving the developing roller with frictional force as in this embodiment.

When the surface linear velocity of the photosensitive drum 1C is Vd (mm / sec) and the developing roller surface linear velocity of the developing device 3C is Vg (mm / sec),
Vg / Vd> 1.2 (2)
If the condition of the expression (2) is satisfied, a margin can be obtained in the function of improving the development efficiency even if slip occurs in the frictional force drive transmission system driven by the developing roller.

  A system for driving the two screws of the developing device 3 with a screw transmission pulley will be described with reference to FIGS. A screw transmission pulley 71 is fixed to the shaft 45 of the developing roller 44, and screw pulleys 72 and 73 are fixed to the two screws 57 and 58, and the pulleys are wound around by a screw transmission belt 75. A screw tension roller 76 that applies tension is applied to the screw transmission belt 75. With such a configuration, the drive from the drive motor 36 is transmitted to rotate the screws 57 and 58 to stir the developer in the developing device 3, thereby preventing banding by gearless transmission and reducing the size and cost. .

  FIG. 8 shows a case where the developing device 3 is positioned in the middle of attachment / detachment, but the development driving coupling 46 is formed in a tapered shape with the side portion 46a of the main body side plate 42 being concave, and the side portion of the developing roller 44 is shown. 46b is formed in the convex taper shape, and both parts are engaging via the uneven | corrugated taper. The surface of the concavo-convex portion of the development drive coupling is made of a high friction material. For example, a surface coat such as rubber or resin. By adopting such a coupling 46, when the developing device 3 is mounted, the developing roller 44 and the developing transmission pulley 43 can be centered, and the rotation unevenness of the developing roller 44 due to the swing of the engaging portion is prevented. Can be prevented.

  The photosensitive drums 1C, 1Y, 1M, and 1BK are configured as described above, and can be prevented from being displaced due to slippage and color misregistration because of the drive transmission by the gear engagement between the motor gear 37 and the photosensitive drum gear 39. In addition, since it is driven by a photosensitive drum gear having a diameter larger than that of the photosensitive drum, even if the vibration of the frequency due to the meshing occurs, the ratio of the outer diameter of the photosensitive drum to the pitch circle diameter of the motor gear is reduced on the photosensitive drum. It becomes inconspicuous as banding. Further, since the developing device 3 is a friction transmission drive, vibration due to the meshing does not occur, so that the image quality of banding does not deteriorate. In the two-component developing device, the developing roller 44 and the photosensitive drums 1C, 1Y, 1M, and 1BK are not in contact with each other, so even if a slight slip occurs in the drive transmission system. The rotation of the photosensitive drum is not affected. Further, since there is one drive motor 36 as a drive source, the size and cost are reduced.

(Embodiment 2)
FIG. 9 is a drawing corresponding to FIG. 2 of the first embodiment showing the second embodiment. In the second embodiment, the drive transmission system of the developing device is not connected to the pulley via a transmission belt as in the first embodiment, and the pulley is directly connected to the drive transmission system of the developing device. It is intended to be transmitted.

  That is, as shown in FIG. 9, the photosensitive drum 1C is a photosensitive drum gear 39 fixed to the shaft 38 of the photosensitive drum 1C at a one-step reduction from the motor gear 37 of the driving motor 36 which is a driving source, as in FIGS. To be driven to rotate. Further, a friction drive pulley 81 is provided on the same axis as the photosensitive drum gear 39 for transmitting the drive to the developing device 3. A development friction pulley 82 is disposed in pressure contact with the friction drive pulley 81. The pressure contact between the friction drive pulley 81 and the development friction pulley 82 provides its function at the mounting position on the main body side plate 42. The surfaces of the pulleys 81 and 82 are made of a high friction coefficient material. For example, a surface coat such as rubber or resin. Other configurations are the same as those of the first embodiment shown in FIGS. Since the coupling 46 is also adopted in the second embodiment, when the developing device 3 is mounted, the developing roller 44 and the developing friction pulley 82 can be centered, and the engaging portion of the coupling 46 is shaken. Therefore, uneven rotation of the developing roller 44 can be prevented.

  In the second embodiment, the same function and effect as those of the first embodiment described in paragraph 0034 can be expected. In addition, in this embodiment, the drive transmission is performed by the pressure contact between the friction drive pulley 81 and the development friction pulley 82 and no belt is used, so the transmission is straightforward and the configuration is simplified.

  The color electrophotographic recording apparatus shown in the first and second embodiments is a preferable example of an image forming apparatus to the last, and may be applied to other devices having the same effect. In addition, the photosensitive drums 1C, 1Y, 1M, and 1BK are only examples of the image carrier, and a detailed design change configuration can be arbitrarily changed or modified during implementation.

  Next, a characteristic effect of the invention described in claim 2 and the following claims will be described. According to the second aspect of the present invention, the number of teeth Zd of the large-diameter gear of the first drive transmission means and the outer diameter Dd (mm) of the image bearing member satisfy the condition of Zd / π × Dd> 2. As a result, even if banding due to gear meshing occurs on the image, the spatial frequency (cycle / mm) of the banding becomes 2 or more, so that it is difficult for human eyes to perceive.

  According to the third aspect of the present invention, in the two-component development, the developing roller is not in contact with the image carrier and the magnetic brush of the developer is in contact with the image carrier. The developing roller surface linear velocity is made faster than the body surface linear velocity. If Vg / Vd> 1.2 or more, even if the developing device slips slightly due to friction transmission driving, there is a margin for the condition that the developing roller surface linear velocity is higher than the image carrier surface linear velocity. Degree is obtained.

  According to the fourth aspect of the present invention, since vibration can be suppressed and the contact area of the portion that generates the frictional force can be increased, slippage of drive transmission is reduced and image deterioration is prevented while making banding inconspicuous. it can.

  According to the fifth aspect of the present invention, an image forming apparatus that suppresses vibration with a simple configuration with a small number of parts, is small in size and low in cost, and does not stand out for banding is obtained. According to the sixth and seventh aspects of the present invention, the developing device can be easily detached from the main unit, and the drive connection is made a frictional connection, so that vibration due to the connection type is suppressed and smooth drive transmission is achieved. It becomes possible.

  According to the eighth and ninth aspects of the invention, the eccentricity due to the connection can be suppressed, the rotation unevenness of the developing roller can be prevented, and the slippage of the drive transmission can be prevented.

  According to the tenth aspect of the present invention, it is possible to prevent vibration generated by the rotational drive of the screw.

1 is an overall schematic configuration diagram of a color electrophotographic recording apparatus according to Embodiment 1 of the present invention. It is a top view of the principal part same as the above by partial fracture | rupture and partial omission. It is a front view of the principal part same as the above. It is a front view of the principal part which shows the modification regarding the rotation direction of a photoconductor drum and a developing roller. It is the graph which showed the spatial frequency and perceptual sensitivity of the banding image. It is a vertical front view of a developing device. 1 is a drawing showing a drive system of a developing device. FIG. 3 is a plan view corresponding to FIG. 2, showing a case where the developing device is located in the middle of attachment / detachment. FIG. 6 is a plan view corresponding to FIG. 2 according to the second embodiment.

Explanation of symbols

1C, 1Y, 1M, 1BK Photosensitive drum (image carrier)
DESCRIPTION OF SYMBOLS 2 Charging roller 3 Developing device 4 Cleaning device 5 Static elimination lamp 6 Writing device 7 Intermediate transfer belt 16 Secondary transfer belt 17 Fixing device 21 Duplex reversing device 36 Drive motor (drive source)
37 motor gear 39 photoconductor drum gear 40 transmission pulley 42 main body side plate 43 development transmission pulley 44 development roller 46 development drive coupling (friction coupling means) 47 transmission belt 53 transmission belt 57, 58 screw 60 outer case 71 screw transmission pulley 81 friction drive pulley 82 Development friction pulley

Claims (10)

A cylindrical image carrier for carrying an electrostatic latent image, a developing device having a developing roller for developing the electrostatic latent image, a first drive transmission means for driving the image carrier from one drive source, and development In an image forming apparatus provided with a second drive transmission means for driving the apparatus,
The first drive transmission means has a large-diameter gear that is directly transmitted from the drive source at a one-stage deceleration and has an outer diameter larger than the outer diameter of the image carrier. The second drive transmission means is a friction transmission means. An image forming apparatus configured to be configured.   2. The condition is set such that Zd / π × Dd> 2 where the number of teeth of the large-diameter gear of the first drive transmission means is Zd and the outer diameter of the image carrier is Dd (mm). The image forming apparatus described.   Conditions are set so that Vg / Vd> 1.2 when the surface linear velocity of the image carrier is Vd (mm / sec) and the developing roller surface linear velocity of the developing device is Vg (mm / sec). The image forming apparatus according to claim 1.   The friction transmission means includes a transmission pulley provided coaxially with the large-diameter gear of the first drive transmission means, a development transmission pulley provided coaxially with the developing roller of the developing device, and teeth for connecting both pulleys by frictional force. The image forming apparatus according to claim 1, wherein the image forming apparatus is configured with a transmission belt that is less.   The friction transmission means is provided coaxially with the large-diameter gear of the first drive transmission means and coaxially with the developing roller of the developing device, and is transmitted in frictional contact with the friction drive pulley. 4. The image forming apparatus according to claim 1, wherein the image forming apparatus comprises a developing friction pulley.   The drive source, the first drive transmission means, and the second drive transmission means are provided on the main body side, the developing device is detachable from the main body, and the second drive transmission means and the development device The image forming apparatus according to claim 4, further comprising friction connecting means for connecting the two.   The drive source, the first drive transmission means, and the second drive transmission means are provided on the main body side, the developing device is detachable from the main body, and the second drive transmission means and the development device 6. An image forming apparatus according to claim 5, further comprising friction connecting means for connecting the two.   The image forming apparatus according to claim 6, wherein the friction coupling means is a coupling.   9. The image forming apparatus according to claim 8, wherein the coupling is a convex and concave taper fitting, and the fitting surface is made of a high friction material.   The developing device includes a developing roller and a screw that stirs the developer, and the screw and the developing roller are configured such that a transmission pulley is connected to each other by a toothless screw transmission belt and interlocked. The image forming apparatus according to 4 or 5.

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