JP5578148B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to a copying machine, a printer, a facsimile, and an image forming apparatus having a combination of these functions. More specifically, a plurality of developing devices are mounted on a rotating rack, and a desired developing device is rotated to a developing position. The present invention relates to an image forming apparatus that moves and performs development.

  In the image forming apparatus, development is performed by supplying charged toner carried on the surface of the developing roller of the developing device to the electrostatic latent image on the surface of the photoreceptor. The toner is frictionally charged by stirring or the like, but it is known that the charge amount of the toner is reduced by natural discharge in a high humidity environment. The toner with a low charge amount is easily detached from the developing roller and may be scattered around the developing device and cause a defect such as an image defect.

  In a so-called rotary developing image forming apparatus in which a plurality of developing devices are mounted on a rotating rack and development is performed by rotating a desired developing device to a developing position, such toner scattering is particularly likely to occur due to rotation of the developing device. .

  Therefore, for example, Patent Document 1 proposes a technique of covering the entire developing rotary with a cylindrical cover in order to prevent toner scattering in a rotary developing type image forming apparatus.

JP-A-9-269655

  However, although it is considered that the toner can be prevented from scattering outside from the cover in the proposed technique, since the cover has an opening, the influence of humidity in the installation environment is unavoidable, and the developing device due to a decrease in the toner charge amount The toner scattering from the toner cannot be suppressed.

  The present invention has been made in view of such conventional problems, and an object of the present invention is to suppress a decrease in toner charge amount in a developing device under a high humidity environment in a so-called rotary developing type image forming apparatus. Another object is to prevent toner scattering from the developing device.

An image forming apparatus according to the present invention that achieves the above-described object includes a case for storing toner, a developer carrier that is partly exposed from an opening formed in the case, and that is rotatably attached to the case. A plurality of developing devices are mounted on a rotating rack, and the rotating rack rotates, so that a desired developing device moves to a developing position where the developer carrier and the image carrier are opposed to each other, and An image forming apparatus for sequentially forming toner images of respective colors on an image carrier, wherein the apparatus main body includes an openable and closable cover means provided with a dehumidifying function member for sealing each of the openings of the plurality of developing devices. And when all the developing devices are in a non-developing position, the openings of all the developing devices are sealed with the cover means, and the case is sealed.

According to another aspect of the present invention, there is provided an image forming apparatus comprising: a case that accommodates toner; and a developer carrier that is partly exposed from an opening formed in the case and is rotatably attached to the case. The plurality of developing devices provided are mounted on a rotating rack, and when the rotating rack rotates, a desired developing device moves to a developing position where the developer carrier and the image carrier face each other, and the image An image forming apparatus for sequentially forming toner images of respective colors on a carrier, wherein the apparatus main body is provided with openable / closable cover means for sealing the openings of the plurality of developing devices, and all the developing devices are When in the developing position, the openings of all the developing devices are sealed with the cover means to seal the case. The cover means is provided at a swingable lever member and at one end of the lever member. Current A lid member having a dehumidification function member for sealing the opening of the device, the biasing member to which the lid member is constantly biased to the lever member in a direction to seal the opening, those on the lever member The lever member is moved against the urging force of the urging member so that the lid member is opened from the closed position where the opening of the developing device is sealed to open the opening of the developing device. When the desired developing device is in the developing position, the lid member is opened by the cam member, and when all the developing devices are in the non-developing position, the cam member is moved to the position. the lid member is characterized Rukoto is in its closed position by the biasing force of the biasing member.

An image forming apparatus according to another invention includes a case for storing toner, and a developer carrier that is partly exposed from an opening formed in the case and is rotatably attached to the case. A plurality of developing devices are mounted on a rotating rack, and the rotating rack rotates, so that a desired developing device moves to a developing position where the developer carrying member and the image carrying member face each other, and the image carrying An image forming apparatus for sequentially forming toner images of respective colors on a body, wherein the apparatus main body is provided with openable and closable cover means for sealing the openings of the plurality of developing devices, and all the developing devices are not developed. When in position, the openings of all the developing devices are sealed with the cover means to seal the case, and the cover means is provided at a swingable lever member and at one end of the lever member. ,developing A lid member that seals the opening of the device, a biasing member that constantly biases the lever member in a direction in which the lid member seals the opening, and a biasing member that abuts the lever member A cam member that moves the lever member against the urging force to move the lid member from a closed position where the opening of the developing device is sealed to an open position where the opening of the developing device is opened And a drive means different from the drive means of the rotating rack for displacing the cam member to open the lever member, and when the desired developing device is at the developing position, the rotating rack The lid member is opened by displacing the cam member by driving means different from the driving means to open the lever member, and when all the developing devices are in the non-developing position, The lid member by an urging force of the urging member Characterized in that it is in its closed position.

  Alternatively, the cam member rotates in synchronization with the rotating rack and is a disk having a concave portion formed on the outer peripheral surface thereof. The lever member protrudes in the direction of the cam member and is biased by the biasing member. An extension portion that is always in contact with the outer peripheral surface of the cam member is provided, and when the desired developing device is at the development position, the extension portion of the lever member comes into contact with a portion other than the recess portion of the cam member and the lid When the member is in the open position and all the developing devices are in the non-development position, the extension portion of the lever member is engaged with the concave portion of the cam member, and the lid member is in the closed position. Also good.

Further, the heater is preferably as the dehumidification function member.

In the image forming apparatus of the present invention, when the developing device is in the non-developing position, the opening of the case of the developing device is sealed with the cover means having the dehumidifying function member, so that the case is sealed. Even in this case, it is possible to suppress a decrease in the toner charge amount. Thereby, toner scattering from the developing device can be suppressed.

Operation | movement explanatory drawing of a cover means. 1 is a schematic diagram showing an embodiment of an image forming apparatus according to the present invention. It is a top view of a rotation rack and its periphery. FIG. 3 is a schematic diagram of a rotating rack and its surroundings when a lid member is in a closed position. The perspective view of a lever member and a lid member. The perspective view of a cover member. Sectional drawing which shows other embodiment of a cover member. Cross-sectional configuration diagram showing another embodiment of the cover means It is a top view of a rotation rack and its periphery. Operation | movement explanatory drawing of a cover means. The perspective view of a lever member and a lid member.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these examples at all.

  FIG. 2 is a schematic diagram of a color printer as an example of the image forming apparatus according to the present invention. A color printer D shown in FIG. 2 includes a rotating rack 10 in which four developing devices 11 are mounted in an apparatus main body 1, a photosensitive drum (image carrier) 20, a charging device 21, an exposure device 22, An intermediate transfer unit 30 and a sheet conveyance path 40 are provided. Hereinafter, when it is necessary to clarify whether the apparatus or member to be described is yellow (Y), magenta (M), cyan (C), or black (K), “(Y ) ”,“ (M) ”,“ (C) ”,“ (K) ”are added to the reference numerals for explanation, and in other cases, the letters are omitted.

  Four developing devices are mounted on the rotating rack 10 side by side in the circumferential direction. Each of the developing devices 11Y, 11M, 11C, and 11K contains toner of each color of yellow, magenta, cyan, and black. Each color toner is carried on the surface of a developing roller (developer carrying member) 13 (shown in FIG. 1) rotatably provided in each developing device 11 and supplied to the photosensitive drum 20. A specific configuration of the developing device 11 will be described later.

  The photosensitive drum 20 rotates clockwise. The rotating rack 10 rotates counterclockwise, and the developing devices 11Y, 11M, 11C, and 11K sequentially move to the developing positions where the developing rollers 13Y, 13M, 13C, and 13K face the photosensitive drum 20. In FIG. 2, the position where the developing device 11K is located is the developing position. A charging device 21 that uniformly charges the surface of the photosensitive drum 20 is disposed around the photosensitive drum 20. In addition, a photoreceptor cleaner 23 that cleans the toner remaining on the surface of the photoreceptor drum 20 is provided between a position facing a primary transfer roller 31 described later and the charging device 21.

  As shown in FIG. 2, an exposure device 22 is provided below the rotating rack 10. The exposure device 22 irradiates the uniformly charged surface of the photoconductive drum 20 with a laser beam in accordance with image information input from the outside, and the surface of the photoconductive drum 20 has an electrostatic latent for each color toner image. Each image is formed.

  The intermediate transfer unit 30 includes an intermediate transfer belt 34 that is wound around a primary transfer roller 31, a roller 32, and a roller 33 and is rotationally driven in the direction of an arrow. The intermediate transfer belt 34 faces the photosensitive drum 20 at the primary transfer roller 31 and further faces the secondary transfer roller 35 at the roller 33. Although not shown, a cleaner is provided for removing toner remaining on the surface of the intermediate transfer belt 34 after the secondary transfer. The intermediate transfer member is not limited to a belt shape, but may have another shape, for example, a drum shape.

  A sheet feeding cassette 41 as a sheet feeding unit is disposed at the lower part of the main body 1 of the color printer D. In the paper feed cassette 41, sheets S such as recording paper are stacked and accommodated. The sheets S are sent one by one in order from the uppermost one by the rotation of the paper feed roller 42.

  A sheet conveying path 40 is generally formed extending from the sheet feeding cassette 41 in the vertical direction. The sheet conveyance path 40 extends from the paper feed cassette 41 through the intermediate transfer unit 30 and the fixing device 44 to the discharge roller pair 45. The sheet S sent out from the paper feed cassette 41 is conveyed upward along the sheet conveyance path 40 by a pair of rotating conveyance rollers 43. The sheet S on which the image has been transferred by the intermediate transfer unit 30 and has been fixed by passing through the fixing device 44 is discharged onto the discharge tray 47 by the rotation of the discharge roller pair 45.

  The apparatus main body 1 of the color printer D includes a control device (not shown) that controls the operation of the entire device, a communication device that exchanges information with external devices, a data processing device that processes and stores image data, and the like. It has been. This includes a drive unit and a heater control unit which will be described later.

  Image formation is performed by a four-cycle method (a method of forming a full-color image by rotating the photosensitive drum 20 four times). That is, an electrostatic latent image of one color is formed on the photosensitive drum 20, and development is performed by the developing device 11 corresponding to the color, and a toner image of the color is formed on the photosensitive drum 20. . The formed toner image is transferred to the intermediate transfer belt 34 by the electric field applied from the primary transfer roller 31. Next, the rotating rack 10 is rotated by 90 °, and the developing device 11 of the other color moves to the developing position, and the electrostatic latent image of the other color is formed on the photosensitive drum 20. The primary transfer of the image is performed. When this operation is repeated for four colors, a full color image in which the four color images are superimposed is formed on the intermediate transfer belt 34.

  On the other hand, the sheet S is fed from the sheet feeding cassette 41, passes through the sheet conveyance path 40, and reaches the opposite portion between the intermediate transfer belt 34 and the secondary transfer roller 35, and is formed on the intermediate transfer belt 34 here. The full color image is transferred to the sheet S by the electric field applied from the secondary transfer roller 35. The full color image is fixed on the sheet S by passing through the fixing device 44, and the sheet S is discharged onto the discharge tray 47 by the rotation of the discharge roller pair 45.

  FIG. 1 shows a partially enlarged view of the carousel 10 and its surroundings. A developing device 11 is detachably mounted on the rotating rack 10. The developing device 11 includes a case 12 and a developing roller (developer carrier) 13 that is partly exposed from the opening 14 formed in the case 12 and is rotatably attached to the case 12. Toner is stored inside. When the developing device 11 moves to a position (development position) where the developing roller 13 faces the photosensitive drum 20 by the rotation of the rotating rack 10, the charged toner carried on the surface of the developing roller 13 is changed between the developing roller 13 and the photosensitive member. The electrostatic latent image on the surface of the photosensitive drum 20 is developed by moving to the photosensitive drum 20 due to a potential difference with the drum 20. When the development is completed, the carousel 10 rotates about 90 °, the next development device moves to the development position, and development of other colors is performed in the same manner. On the other hand, when development is not performed such as when the main power is off or in a standby state, all the developing devices 11 are set to the non-development position.

  By the way, when development is not performed, for example, when the installation environment of the apparatus is high humidity, the toner charge amount in the case 12 of the developing apparatus 11 gradually decreases and is carried on the surface of the developing roller 13. The toner may be detached from the developing roller 13 and scattered around the developing device 11.

  Therefore, in the present invention, when the developing device 11 is in the non-developing position, the cover means 50 that seals the opening 14 of the developing device 11 is provided to suppress a decrease in the toner charge amount in the case 12. Hereinafter, the cover means 50 will be described with reference to FIGS. FIG. 3 is a plan view of the rotating rack 10 and its surroundings.

  Cover means 50 are provided corresponding to each of the four developing devices 11. The cover means 50 includes a lever member 51 whose one end is swingably supported by a shaft 52, a lid member 56 supported by a shaft 55 on the other end of the lever member 51, and a lever that is extrapolated to the shaft 52. A torsion coil spring (biasing member) 54 that constantly urges the member 51 in the direction of the rotating rack 10 and a circumferential direction of a shaft 62 (shown in FIG. 2) extend in the radial direction at intervals of about 90 °, and the lever member 51 And four slender plate-like cam plates (cam members) 61 that move the lever member 51 from the closed position to the open position.

  As shown in FIG. 3, the carousel 10 is rotationally driven via a gear 16 and a gear 17 by a motor 18 provided on the substrate 19 of the apparatus main body 1. The on / off of the motor 18 is controlled by a signal from a position detecting means (not shown) that detects the position of the developing device 11.

  As shown in FIG. 1, a plunger 64 that can move freely with respect to a solenoid main body 63 of a solenoid (driving means) S is connected to a midway portion of the cam plate 61 in the radial direction. A compression coil spring 65 that constantly urges the plunger 64 in a direction in which the plunger 64 protrudes outward is externally attached to the plunger 64. When the solenoid S is energized, the plunger 64 is pulled into the solenoid body 63 against the urging force of the compression coil spring 65. Then, the movement of the plunger 64 causes the cam plate 61 to swing clockwise about the shaft 62. Then, the outer end of the cam plate 61 comes into contact with the contact portion 53 of the lever member 51, and the lever member 51 is moved away from the rotating rack 10. Accordingly, the lid member 56 is in an open position where the opening 14 of the developing device 11 is opened.

  On the other hand, when the energization to the solenoid S is stopped, the plunger 64 is pulled out from the solenoid body 63 by the urging force of the compression coil spring 65, and the cam plate 61 swings counterclockwise about the shaft 62. Then, the contact between the outer end of the cam plate 61 and the contact portion 53 of the lever member 51 is released, and the lever member 51 moves in the direction of the rotating rack 10 by the biasing force of the torsion coil spring 54, and the cover member 56. Is a closed position for sealing the opening 14 of the developing device 11.

  Sealing of the opening 14 of the developing device 11 by the lid member 56 is performed, for example, when a series of image formation is finished and then the so-called standby state is entered, or when the main power supply of the apparatus main body is turned off. . In this case, after rotating the rotating rack 10 by a predetermined amount so that all the developing devices 11 are in the non-developing position, the energization to the solenoid S is stopped and the opening 14 of the developing device 11 is covered with the lid member 56. Seal. FIG. 4 shows a state in which the openings 14 of all the developing devices 11 are sealed by the lid member 56. In this figure, the lever member 51 and the cam plate 61 are omitted.

  When an image formation instruction is issued, the solenoid S is energized, the outer end of the cam plate 61 is brought into contact with the contact portion 53 of the lever member 51, and the lever member 51 is moved away from the rotating rack 10. The cover member 56 is moved to the open position. Next, the rotating rack 10 is rotated to move the desired developing device 11 to a developing position facing the photosensitive drum 20.

  As shown in FIGS. 5 and 6, the lid member 56 is swingably supported by the pair of lever members 51 by pivot shafts 55 formed at both ends in the longitudinal direction. As a result, slight positional deviation or angular deviation of the lid member 56 caused by dimensional accuracy or the like is absorbed, and the opening 14 of the developing device 11 is reliably sealed by the lid member 56.

  The material of the lid member 56 is not particularly limited, but the surface that contacts the periphery of the opening 14 of the developing device 11 preferably has flexibility such as a foaming agent or a rubber agent. Thereby, adhesiveness with the opening part 14 periphery improves, and sealing performance becomes high. The shape of the lid member 56 is preferably close to the periphery of the opening 14 of the developing device 11 but not in contact with the developing roller 13. As a result, the toner carried on the surface of the developing roller 13 is not subjected to pressure stress by the lid member 56.

In addition, as shown in FIG. 7, the heater 57 as dehumidification function member disposed on the inner surface of the lid member 56, one holding a low humidity in the developing device 11. For example, when the inside of the developing device 11 is heated to a temperature not exceeding 45 ° C., the humidity is maintained at 60% or less that does not cause a decrease in the toner charge amount. The heater 57 is preferably operated when the main power supply is turned off or in a standby state, for example.

  As the dehumidifying function member, in addition to the heater 57, a reversible moisture absorbent such as activated carbon may be used. When moisture in the developing device 11 is adsorbed by the hygroscopic agent, the inside of the developing device 11 is maintained at a low humidity. The moisture adsorbed by the hygroscopic agent is desorbed from the hygroscopic agent due to an increase in the temperature in the apparatus during image formation, and the hygroscopic agent recovers the adsorption performance.

  8 to 11 show another embodiment of the cover means 50. As shown in FIG. Note that the rotating rack 10, the photosensitive drum 20, the intermediate transfer unit 30, and the sheet conveyance path 40, to which the developing device 11 is mounted, are the same as those in the above-described embodiment, and thus description thereof is omitted here. Moreover, the same code | symbol is attached | subjected to the same member and the same part as the said embodiment.

  In the cover means of this embodiment, a disc-shaped cam plate 70 having four recesses 71Y, 71M, 71C, 71K formed at equal intervals on the outer peripheral surface is used, and an extended portion 58 protruding in the direction of the cam plate 70 is used. The lever member 51 formed with is used. As shown in FIG. 11, the extending portion 58 has a shape bent outward substantially vertically after extending outward from the middle in the longitudinal direction of the pair of lever members 51. Then, the extension portion 58 of the lever member 51 is always in contact with the outer peripheral surface of the cam plate 70 by the torsion coil spring 54 extrapolated to the shaft 52, and the extension portion 58 is fitted into the recess 71 of the cam plate 70. As a result, the lever member 51 swings so that the lid member 56 is in the closed position.

  FIG. 8 is a state diagram when the developing device 11K is in the developing position. At this time, the extending portion 58 of the lever member 51 comes into contact with a portion other than the concave portion 71 on the outer peripheral surface of the cam plate 70, the lever member 51 is lifted, and the lid member 56 is in the open position.

  When the rotating rack 10 and the cam plate 70 are rotated counterclockwise from the state shown in FIG. 8 to the position shown in FIG. 10, the extended portion 58 of the lever member 51 is fitted into the recess 71 of the cam plate 70, and the torsion coil The lever member 51 swings in the direction of the rotating rack 10 about the shaft 52 by the biasing force of the spring 54. Then, the lid member 56 is closed and the opening 14 of the developing device 11 is sealed. At this time, the opening 14 is similarly sealed by the lid member 56 in the other developing devices 11.

  In the cover means having such a configuration, the extension portion 58 of the lever member 51 is fitted into the four recesses 71 of the cam plate 70 in order while the cam plate 70 makes one rotation together with the rotating rack 10, and the cover member 56 has 4 pieces. The closed position is reached. In order to avoid such opening and closing of the originally unnecessary lid member 56, four cam plates 70 are provided for each developing device 11, and one recess 71 is formed in the cam plate 70, so that one rotation of the rotating rack is performed. The lid member 56 may be in the closed position only once.

  In the developing device of the present invention, when the developing device is in the non-developing position, the opening of the case of the developing device is sealed with the cover means to seal the case, so that the toner charge amount even in a high humidity environment Can be suppressed. As a result, toner scattering from the developing device is suppressed, which is useful.

D color printer (image forming device)
S Solenoid (drive means)
10 rotating rack 11 developing device 12 case 13 developing roller (developer carrier)
14 Opening 20 Photoconductor drum (image carrier)
50 cover means 51 lever member 54 torsion coil spring (biasing member)
56 Lid member 58 Extension part 61 Cam plate (cam member)
57 Heating heater 70 Cam plate (cam member)

Claims (5)

A plurality of developing devices including a case for storing toner and a developer carrying member that is partly exposed from an opening formed in the case and is rotatably attached to the case are mounted on a rotating rack. Rotating the rotating rack moves a desired developing device to a developing position where the developer carrying member and the image carrying member face each other, and forms each color toner image on the image carrying member in order. In the device
The apparatus main body is provided with openable and closable cover means having a dehumidifying function member for sealing the openings of the plurality of developing devices, respectively, and when all the developing devices are in the non-developing position, An image forming apparatus, wherein the opening is sealed by the cover means to seal the case. A plurality of developing devices including a case for storing toner and a developer carrying member that is partly exposed from an opening formed in the case and is rotatably attached to the case are mounted on a rotating rack. Rotating the rotating rack moves a desired developing device to a developing position where the developer carrying member and the image carrying member face each other, and forms each color toner image on the image carrying member in order. In the device
The apparatus main body is provided with openable and closable cover means for sealing the openings of the plurality of developing devices, respectively, and when all the developing devices are in the non-developing position, the openings of all the developing devices are covered with the cover means. And seal the case with
The cover means includes a swingable lever member, a lid member provided at one end of the lever member and having a dehumidifying function member for sealing the opening of the developing device, and the lid member is the opening. An urging member that constantly urges the lever member in a direction of sealing the portion; and the lid member that moves against the urging force of the urging member in contact with the lever member and moves the lever member And a cam member that moves the opening of the developing device from the closed position where the opening is sealed to the open position where the opening of the developing device is opened,
When the desired developing device is at the developing position, the lid member is opened by the cam member, and when all the developing devices are at the non-developing position, the lid member is moved by the urging force of the urging member. an image forming apparatus comprising Rukoto is in its closed position. A plurality of developing devices including a case for storing toner and a developer carrying member that is partly exposed from an opening formed in the case and is rotatably attached to the case are mounted on a rotating rack. Rotating the rotating rack moves a desired developing device to a developing position where the developer carrying member and the image carrying member face each other, and forms each color toner image on the image carrying member in order. In the device
The apparatus main body is provided with openable and closable cover means for sealing the openings of the plurality of developing devices, respectively, and when all the developing devices are in the non-developing position, the openings of all the developing devices are covered with the cover means. And seal the case with
The cover means includes a swingable lever member, a lid member provided at one end of the lever member for sealing the opening of the developing device, and a direction in which the lid member seals the opening. An urging member that constantly urges the lever member; and the lever member is moved against the urging force of the urging member in contact with the lever member to move the lid member to the developing device. A cam member that moves from a closed position where the opening is sealed to an open position where the opening of the developing device is opened; and a drive means for the carousel that displaces the cam member to open the lever member. Has separate drive means,
When the desired developing device is in the developing position, the lid member is set to the open position by displacing the cam member by the driving means different from the driving means for the rotating rack to open the lever member. The image forming apparatus is characterized in that when all the developing devices are in the non-developing position, the lid member is closed by the urging force of the urging member . The cam member rotates in synchronization with the rotating rack, and is a disk having a recess formed on the outer peripheral surface.
The lever member protrudes in the direction of the cam member, and has an extending portion that always contacts the outer peripheral surface of the cam member by the biasing force of the biasing member;
When the desired developing device is in the developing position, the extension portion of the lever member comes into contact with a portion other than the concave portion of the cam member, and the lid member is in the open position.
The image forming apparatus according to claim 2, wherein when all the developing devices are in a non-developing position, the extension portion of the lever member engages with the concave portion of the cam member, and the lid member is in the closed position. The dehumidification function member image forming apparatus according to claim 1 or 2 or 4 wherein the heater.