JP2008070758A - Developing device and image forming apparatus equipped therewith - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotary type developing device equipped with a plurality of developing units arranged around a shaft line, where the vibration of the developing unit itself is reduced and positional relation between the developing unit and an image carrier is appropriately held. <P>SOLUTION: The developing device 30 is equipped with a support member 37 supporting the developing unit 32, and a torsion coil spring 42 that is a biasing means provided between the support member 37 and the developing unit 32 and biasing the developing unit 32 toward a photoreceptor drum 21. The supporting part 40 of the support member 37 for supporting the developing unit 32 is equipped with a vibration-proof member 50 holding the developing unit 32 and absorbing the vibration. Thus, the vibration of the developing unit 32 itself is reduced. Therefore, the positional relation between the developing unit 32 and the photoreceptor drum 21 is prevented from being adversely affected by the vibration when rotating and moving, and the positional relation between them is appropriately held. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a developing device applicable to an electrophotographic image forming apparatus typified by a copying machine or a printer, and more particularly to a rotary developing device in which a plurality of developing devices are arranged around an axis. The present invention also relates to an image forming apparatus equipped with the developing device.

  Among image forming apparatuses typified by copying machines and printers, tandem or rotary systems are widely known as methods for transferring a plurality of different color toner images onto paper in image forming apparatuses for color printing. .

  The tandem method is a method in which a plurality of image forming units each having an individual image carrier for each color are arranged in a line along the rotation direction of a transfer conveying member or an intermediate transfer member, and toner images are transferred sequentially. It is. In this method, a multiple full-color toner image in which toner images of a plurality of colors are superimposed is completed while the transfer conveying member or the intermediate transfer member is rotated once, so that the image forming operation can be repeated in a short time. There is.

  However, in the tandem method, a plurality of image forming units are arranged in a line along the rotation direction of the transfer conveyance member or the intermediate transfer member in the horizontal, vertical, or oblique direction, which leads to an increase in the size of the image forming apparatus. There is concern that this problem will occur.

  In contrast, the rotary system is a system in which a toner image is sequentially developed by rotating a photosensitive drum a plurality of times for each color with respect to a single image carrier. In this method, since the image carrier needs to be rotated a plurality of times for each color, the time required for image formation is longer than in the tandem method, but there is an advantage that only one image carrier is required. is there. As a result, the image forming apparatus can be miniaturized, and therefore, a rotary system is adopted for a small color printer.

  As described above, a rotary developing device suitable for downsizing an image forming apparatus for color printing includes a plurality of developing devices arranged around an axis, and selects one of the plurality of developing devices, A toner image is formed by developing the electrostatic latent image while positioning it at a developing position facing the image carrier on which the electrostatic latent image is formed by rotating around the axis.

However, in a rotary developing device, there is a concern that vibration is likely to occur when a rotary rack equipped with a plurality of developing devices rotates and moves for switching development colors. Therefore, in order to solve such a problem, an image forming apparatus equipped with a rotary type developing device has been proposed to reduce the vibration during the rotary movement of the rotary rack. Can do.
Japanese Patent Laying-Open No. 2005-3000946 (5th page, FIG. 2)

  In the developing device described in Patent Document 1, a support plate that supports a rotary developing unit (rotary rack) and a photoreceptor (image carrier) is held by a frame member of the image forming apparatus via a vibration isolating member. Therefore, vibration generated in other places is prevented from being transmitted to the rotary developing unit and the photosensitive member. However, in this developing apparatus, there is no mention of a method for mounting the developing device arranged in the rotary developing unit to the rotary developing unit. Therefore, the vibration during the rotational movement of the rotary developing unit may adversely affect the positional relationship between the developing device and the photosensitive member. Thereby, for example, when developing the electrostatic latent image on the surface of the photoconductor in a non-contact manner, the distance between the surface of the developing roller of the developing unit and the surface of the photoconductor becomes unstable, and there is a possibility that an image defect occurs.

  The present invention has been made in view of the above points, and includes a plurality of developing units arranged around an axis, and selects one of the plurality of developing units by rotating around the axis to a developing position. In a rotary developing device that positions and develops an electrostatic latent image, vibration of the developing device itself can be reduced when rotating, and the positional relationship between the developing device and the image carrier can be properly maintained. An object of the present invention is to provide a developing device capable of forming a high-quality image. It is another object of the present invention to provide a high-performance image forming apparatus equipped with such a developing device.

  In order to solve the above-described problems, the present invention includes a plurality of developing devices arranged around an axis, and selects one of the plurality of developing devices, and rotates around the axis to move the electrostatic latent image. In a rotary type developing device that forms a toner image by developing the electrostatic latent image, and a supporting member that supports the developing unit, and a supporting member that supports the developing device. A biasing means provided between the member and the developing unit, for biasing the developing unit toward the image carrier, and a supporting member of the support member that supports the developing unit and holds the developing unit; And a vibration isolating member that absorbs the vibration.

  In the developing device having the above-described configuration, the vibration-proof member is formed of a low-rebound elastic member.

  In the present invention, the developing device is mounted on the image forming apparatus.

  According to the configuration of the present invention, a plurality of developing devices arranged around the axis is provided, and one of the plurality of developing devices is selected, and the electrostatic latent image is formed by rotating around the axis. In a rotary type developing apparatus that positions a developing position opposite to an image carrier and develops an electrostatic latent image to form a toner image, a supporting member that supports the developing device, and the support member and the developing device An anti-vibration device provided between the urging means for urging the developing device toward the image carrier and a support member of the supporting member that supports the developing device, and holds the developing device and absorbs vibrations thereof. Therefore, the vibration of the developing device itself can be reduced. As a result, it is possible to prevent the vibration during the rotational movement from adversely affecting the positional relationship between the developing device and the image carrier, and to maintain the positional relationship appropriately. Therefore, the development capable of preventing the occurrence of image defects due to the unstable distance between the developing device and the image carrier due to the vibration of the developing device itself and forming a high-quality image. A device can be obtained.

  In addition, since the vibration-proof member is composed of a low-repulsion elastic member, the developing device can be held by the low-repulsion elastic member that has excellent shock absorption, low rebound resilience, and high stability. . Therefore, it is possible to improve the action of reducing the vibration of the developing device itself and the action of stabilizing the distance between the developing device and the image carrier.

  In the present invention, since the developing device is mounted on the image forming apparatus, vibration of the developing device itself can be reduced, and the positional relationship between the developing device and the image carrier can be appropriately maintained. A high-performance image forming apparatus capable of performing quality image formation can be obtained.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  First, an outline of the structure of an image forming apparatus equipped with a developing device according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a left side view of a schematic vertical section showing a schematic structure of a color printer which is an example of an image forming apparatus. This color printer is a type using a rotary developing device and an intermediate transfer belt. In FIG. 1, the right side is the front side of the printer, and the left side is the back side.

  As shown in FIG. 1, a paper cassette 3 is disposed below the inside of the main body 2 of the printer 1. Inside the paper cassette 3, paper P is stacked and stored. Then, the paper P is sent out toward the upper right of the paper cassette 3 in FIG. The paper cassette 3 can be pulled out horizontally from the front side of the main body 2, that is, from the right side in FIG.

  A paper feed paper transport path 4, a paper feed transport roller 5, a registration roller 6, and an image forming unit 20 are disposed downstream of the paper cassette 3 in the paper transport direction. The image forming unit 20 includes a photosensitive drum 21 which is a rotating image carrier at the center thereof. The photosensitive drum 21 rotates counterclockwise in FIG. Around the photosensitive drum 21, a charging device 22, a developing device 30, and a drum cleaning device 60 are sequentially arranged along the rotation direction.

  The developing device 30 is mainly composed of a rotary rack 31 that rotates clockwise in FIG. 1, and a rotary type developing device in which a total of four developing devices 32 are arranged at equal intervals around the axis on the rotary rack 31. It is. The four developing devices 32 are a black developing device 32B, a yellow developing device 32Y, a magenta developing device 32M, and a cyan developing device 32C. The rotary rack 31 is rotated around the axis by driving means (not shown). Then, the developing device 30 selects one of the four developing devices 32, sequentially moves it to a developing position facing the photosensitive drum 21, positions the photosensitive drum, and supplies each color toner to the photosensitive drum. The electrostatic latent image on the surface 21 is developed to form a toner image. Above the image forming unit 20, a toner supply container 7 for supplying toner to the developing device 30 and a supply pipe 8 are provided.

  An optical unit 9 is provided above the image forming unit 20, and a laser beam L is emitted from the optical unit 9 toward the photosensitive drum 21. The dotted line in the figure indicates the laser beam L.

  An intermediate transfer belt 10 using an intermediate transfer member in the form of an endless belt is disposed immediately below the photosensitive drum 21. The intermediate transfer belt 10 is supported by being wound around a plurality of rollers, and rotates clockwise in FIG. The intermediate transfer belt 10 is pressed against the photosensitive drum 21 from below to form a primary transfer portion 70.

  A secondary transfer unit 11 is disposed at a position where the intermediate transfer belt 10 is suspended on the sheet conveyance path. The paper P is inserted into the secondary transfer nip portion formed in the secondary transfer portion 11 to be brought into pressure contact with the intermediate transfer belt 10 and the toner image is transferred. A belt cleaning unit 12 is provided downstream of the secondary transfer unit 11 in the sheet conveyance direction.

  A fixing unit 13, a discharge paper transport path 14, and a paper discharge unit 15 are disposed downstream of the image forming unit 20 and the secondary transfer unit 11 in the paper transport direction. The paper discharge unit 15 is provided on the upper surface of the main body 2 at a position where the printed paper P can be taken out from the outside.

  A paper conveyance path 16 for double-sided printing is disposed below the fixing unit 13 and the secondary transfer unit 11 and between the paper cassette 3. The double-sided printing paper conveyance path 16 branches from the middle of the discharge paper conveyance path 14, passes under the fixing unit 13 and under the secondary transfer unit 11, and conveys the paper for paper feeding immediately upstream of the registration roller 6. It merges with Road 4.

  Next, a detailed configuration around the image forming unit 20 of the printer 1 will be described with reference to FIG. FIG. 2 is a partially enlarged vertical cross-sectional view showing the periphery of the image forming unit.

  As shown in FIG. 2, the image forming unit 20 includes a photosensitive drum 21 as an image carrier at the center thereof. As described above, the charging device 22, the developing device 30, and the drum cleaning device 60 are arranged in the vicinity of the photosensitive drum 21 in the rotation direction. The primary transfer portion 70 in which the photosensitive drum 21 and the intermediate transfer belt 10 are in pressure contact is provided between the developing device 30 and the drum cleaning device 60 along the rotation direction of the photosensitive drum 21.

  The photosensitive drum 21 extends in the paper width direction perpendicular to the paper transport direction in the printer 1, that is, the depth direction of the paper surface of FIG. 2, and is arranged with its axis direction horizontal. The photosensitive drum 21 is an inorganic photosensitive drum in which an amorphous silicon photosensitive layer, which is an inorganic photoconductive material, is provided on the outside of a conductive roller-shaped substrate made of aluminum or the like by vacuum deposition or the like, and has a diameter of 30 mm. It is. The photosensitive drum 21 is rotated by a driving device (not shown) so that the peripheral speed thereof is substantially the same as the paper conveyance speed (for example, 210 mm / sec).

  The charging device 22 includes a charging roller 22 a in contact with the photosensitive drum 21 inside. The charging roller 22 a is pressed against the photosensitive drum 21 with a predetermined pressure, and rotates according to the rotation of the photosensitive drum 21. The surface of the photosensitive drum 21 is uniformly charged with a predetermined polarity and potential by the charging roller 22a.

  As described above, the developing device 30 is mainly composed of the rotary rack 31, and a total of four developing devices 32 are arranged around the axis line at equal intervals on the rotary rack 31. Each developing device 32 is provided with a photosensitive member non-contact type developing roller 33 in the vicinity of the photosensitive drum 21. A bias having the same polarity as the charging polarity of the photosensitive drum 21 is applied to the developing roller 33. The developing roller 33 charges the toner, which is a developer, and moves it to the electrostatic latent image on the surface of the photosensitive drum 21 to develop the electrostatic latent image. The toner is accommodated in a toner replenishing container 7 (see FIG. 1), conveyed to the location of the developing device 30 by the replenishing pipe 8, and replenished. When the toner is replenished, the replenishment pipe 8 extends to a position indicated by a two-dot chain line shown in FIG. The detailed configuration of the developing device 30 will be described later.

  The primary transfer unit 70 is provided with a primary transfer roller 71 that comes into contact with the photosensitive drum 21 via the intermediate transfer belt 10. A primary transfer nip portion where the photosensitive drum 21 and the intermediate transfer belt 10 are in contact with each other is formed at a location where the primary transfer roller 71 is provided. The primary transfer roller 71 rotates according to the rotation of the intermediate transfer belt 10 by contacting the intermediate transfer belt 10 without having a driving device. The primary transfer roller 71 is applied with a primary transfer bias having a polarity opposite to the charged charge of the photosensitive drum 21 and the toner as necessary.

  The intermediate transfer belt 10 is composed of a single layer resin belt formed only of a synthetic resin such as polyimide or an elastic belt having a rubber layer laminated on the surface of such a synthetic resin, and is wound around a plurality of rollers. It is supported.

  As shown in FIG. 2, the drum cleaning device 60 is disposed further downstream of the primary transfer unit 70 along the rotation direction of the photosensitive drum 21. The drum cleaning device 60 includes a cleaning roller 62 and a discharge screw 63 inside the housing 61, and a cleaning blade 64 between the housing 61 and the photosensitive drum 21.

  The cleaning roller 62 and the cleaning blade 64 are urged by an elastic member such as a spring (not shown) and are pressed against the photosensitive drum 21. The cleaning roller 62 and the cleaning blade 64 extend in the axial direction of the photosensitive drum 21 and have substantially the same axial length as the photosensitive layer of the photosensitive drum 21. In order to perform efficient cleaning, the cleaning roller 62 is driven by a driving device (not shown) so that the peripheral speed of the cleaning roller 62 is about 15 to 20% higher than the peripheral speed of the photosensitive drum 21. It is rotated in the direction opposite to the rotation direction of 21. After the primary transfer of the toner image to the intermediate transfer belt 10 by such a cleaning roller 62 and the cleaning blade 64, the toner remaining on the surface of the photosensitive drum 21 is removed and cleaned. The toner removed from the surface of the photosensitive drum 21 is once collected in the housing 61 and discharged to the outside by the discharge screw 63.

  Next, the detailed configuration of the developing device 30 will be described with reference to FIGS. 3 to 5 in addition to FIG. 3 is a partial perspective view of a rotary rack of the developing device, FIG. 4 is a partial perspective view of a developing device provided in the developing device, and FIG. 5 is a perspective view of a supporting member that supports the developing device. Since the four color developing devices 32 have the same basic structure, the description of the identification symbols for each color such as “Y”, “M”, “C”, and “B” is omitted unless otherwise specified. In FIG. 3 and FIG. 5, other members corresponding to the developing devices 32Y, 32M, 32C, and 32B are given identification symbols “Y”, “M”, “C”, and “B”. Unless otherwise specified, the description of the identification symbols in the following text is omitted for these other members.

  The developing device 30 shown in FIG. 2 mainly includes a rotary rack 31 shown in FIG. In the rotary rack 31, four developing devices 32 shown in FIG. 4 are arranged at equal intervals around the axis (see FIG. 2).

  As shown in FIG. 4, the developing device 32 has a fan-shaped cross section in a direction perpendicular to the axis, and its central angle is approximately 90 °. A developing roller 33 is provided at a location on the outer peripheral surface corresponding to the fan-shaped arc. Gap rollers 33 a are provided at both ends of the developing roller 33. When the gap roller 33a comes into contact with the photosensitive drum 21, the distance between the surface of the developing roller 33 and the surface of the photosensitive drum 21 is set with an appropriate gap.

  The developing device 32 includes a shaft portion 34 for mounting on the rotary rack 31 and a rectangular parallelepiped-shaped projection 35 at both ends in the axial direction thereof, and these protrude outward in the axial direction. In the protrusion 35, one side surface 36 extending in a rectangular parallelepiped shape is directed in a direction where the developing roller 33 faces the photosensitive drum 21. In FIG. 4, only one end portion of the developing device 32 in the axial direction is drawn, but the other end portion is similarly provided with a shaft portion 34 and a protrusion 35.

  As shown in FIG. 3, the rotary rack 31 includes substantially disc-shaped support members 37 at both ends in the axial direction. A shaft portion 38 serving as the rotation center of the rotary rack 31 is provided at the center of the rotation surface of the support member 37. In the rotary rack 31, the four developing devices 32 are each supported by a support member 37.

  As shown in FIG. 5, the support member 37 includes four bearing portions 39 and four slit-shaped support portions 40. Each of the bearing portion 39 and the support portion 40 is paired to correspond to the four developing devices 32, the shaft portion 34 of the developing device 32 is the bearing portion 39, and the protrusion 35 is the support portion 40. Engage. The bearing portion 39 and the support portion 40 that form a pair are formed so as to extend from the outer edge of the support member 37 in the same direction. For example, the bearing portion 39B and the support portion 40B corresponding to the black developing device 32B extend in the same direction from the outer edge of the support member 37 so that the developing device 32B can be inserted in the direction of arrow A shown in FIG. In this way, the four developing devices 32 are attached to the support member 37 from the direction rotated by 90 degrees about the axis center with respect to the bearing portions 39 and the support portions 40 corresponding thereto. (See FIG. 3).

  In the support portion 40, as shown in FIG. 5, an opening 41 is provided at one side of the both side surfaces along the direction in which the protrusion 35 is inserted from the outer edge of the support member 37. With this opening 41, the support member 37 is opened from the portion of the shaft portion 38 to the inside of the support portion 40.

  As shown in FIG. 3, the support member 37 is provided with four torsion coil springs 42. Each of the four torsion coil springs 42 corresponds to the four developing devices 32, and the coil portion is provided in the vicinity of each support portion 40 and is wound around a support shaft 43 that protrudes in the axial direction from the support member 37. Attached. One end of the torsion coil spring 42 is hooked on a locking portion 44 provided on the support member 37. The other end of the torsion coil spring 42 extends toward the support portion 40, and an intermediate portion thereof contacts the protrusion 35 of the developing device 32 through an opening 41 (see FIG. 5) provided in the support portion 40. 32 is energized. In this way, the torsion coil spring 42 is provided between the support member 37 and the developing device 32 and acts as an urging means for urging the developing device 32 toward the photosensitive drum 21.

  As shown in FIG. 5, a vibration isolating member 50 is provided on the inner surface of the support portion 40 facing the surface on which the opening 41 is provided. The anti-vibration member 50 is made of a low-rebound elastic member such as a low-rebound sponge or urethane foam, and has an elongated flat plate shape.

  As shown in FIG. 3, when the protrusion 35 of the developing device 32 is inserted into the support portion 40, the developing device 32 is biased toward the photosensitive drum 21 by the torsion coil spring 42, that is, toward the vibration isolation member 50. Is done. As a result, the vibration isolating member 50 is slightly compressed between the inner surface of the support portion 40 and the side surface 36 (see FIG. 4) of the protrusion 35 to hold the developing device 32 in an elastically deformed form. In this way, the vibration isolating member 50 absorbs the vibration of the developing device 32.

  As described above, the image forming apparatus includes a plurality of developing devices 32 arranged around the axis, selects one of the plurality of developing devices 32, and rotates around the axis to form an electrostatic latent image. In a rotary developing device 30 that positions the developing position facing the photosensitive drum 21 that is a carrier and develops the electrostatic latent image to form a toner image, a support member 37 that supports the developing device 32, A torsion coil spring 42 that is provided between the support member 37 and the developing device 32 and urges the developing device 32 toward the photosensitive drum 21, and supports the developing device 32 of the support member 37. Since the anti-vibration member 50 is provided on the supporting portion 40 and holds the developing device 32 and absorbs vibrations thereof, the vibration of the developing device 32 itself can be reduced. As a result, it is possible to prevent the vibration during the rotational movement from adversely affecting the positional relationship between the developing device 32 and the photosensitive drum 21, and to maintain the positional relationship appropriately. Therefore, it is possible to prevent the occurrence of image defects due to the unstable distance between the developing device 32 and the photosensitive drum 21 due to the vibration of the developing device 32 itself, and to form a high-quality image. A possible developing device 30 can be obtained.

  Further, since the vibration isolating member 50 is composed of a low rebound resilience member, the developing device 32 can be held by the low rebound resilience member having excellent shock absorption, low rebound resilience, and high stability. Therefore, it is possible to improve the action of reducing the vibration of the developing device 32 itself and the action of stabilizing the distance between the developing device 32 and the photosensitive drum 21.

  In the present invention, since the developing device 30 is mounted on the printer 1 as an image forming apparatus, the vibration of the developing device 32 itself is reduced, and the positional relationship between the developing device 32 and the photosensitive drum 21 is properly maintained. Therefore, it is possible to obtain a high-performance printer 1 capable of performing high-quality image formation.

  Although the embodiments of the present invention have been described above, the scope of the present invention is not limited to these embodiments, and various modifications can be made without departing from the spirit of the invention.

  For example, in the above-described embodiment, the vibration isolation member 50 is provided only on the inner surface of the support portion 40 that faces the surface on the side where the opening 41 is provided, but the opening 41 is not blocked. You may provide also in the inner surface of the side in which the opening part 41 was provided.

  The present invention includes a plurality of developing units arranged around an axis, and selects one of the plurality of developing units, and faces an image carrier on which an electrostatic latent image is formed by rotating around the axis. It can be used in a rotary type developing device that positions the developing position and develops the electrostatic latent image to form a toner image.

1 is a left side view of a schematic vertical section of a printer equipped with a developing device according to an embodiment of the present invention. FIG. 2 is a partially enlarged vertical sectional view showing the periphery of the image forming unit in FIG. 1. FIG. 3 is a partial perspective view of a rotary rack of the developing device shown in FIG. 2. FIG. 4 is a partial perspective view of the developing device shown in FIG. 3. FIG. 4 is a perspective view of a support member that supports the developing device shown in FIG. 3.

Explanation of symbols

1 Printer (image forming device)
20 Image forming unit 21 Photosensitive drum (image carrier)
DESCRIPTION OF SYMBOLS 30 Developing device 31 Rotary rack 32 Developing device 33 Developing roller 33a Gap roller 35 Projection 36 Side surface 37 Support member 40 Support portion 41 Opening portion 42 Torsion coil spring (biasing means)
50 Anti-vibration member

Claims (3)

A developing position that includes a plurality of developing devices arranged around an axis, selects one of the plurality of developing devices, and rotates around the axis to face an image carrier on which an electrostatic latent image is formed In the rotary type developing device for developing the electrostatic latent image and forming a toner image,
A supporting member that supports the developing unit; an urging unit that is provided between the supporting member and the developing unit and urges the developing unit toward the image carrier; and the supporting member supports the developing unit. A developing device comprising: a vibration isolating member that is provided in the support portion and holds the developing device and absorbs vibrations thereof.   The developing device according to claim 1, wherein the vibration isolating member is formed of a low rebound elastic member.   An image forming apparatus comprising the developing device according to claim 1.

Images