JP3884960B2 - Driving device and color image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a driving device used for a copying machine, a printer, and the like, and a color image forming apparatus including the driving device.
[0002]
[Prior art]
In order to solve the problem of waste of the developer in the in-line type color image forming apparatus, a method of controlling the rotation of the electrophotographic photosensitive member and the developing device separately to minimize the rotation of the developing device is considered. Further, as a countermeasure against color misregistration of a plurality of colors peculiar to in-line, a method of controlling the rotation of the photoconductor with a motor independent of each color has been adopted. In order to realize a combination of both at a low cost, a method may be considered in which the photosensitive member and the developing device are driven by one motor for each color, and a clutch for controlling rotation and stop is inserted in the development driving.
[0003]
In the development drive of the conventional image forming apparatus, an electromagnetic clutch or a spring clutch is often used, but there are problems such as high cost, limited shape, and malfunction due to slip.
[0004]
As a mechanical clutch for avoiding this, there is a planetary clutch that engages and separates from the other gear by revolving the gear.
[0005]
[Problems to be solved by the invention]
However, in the planetary clutch, tooth surface wear resulting from the impact of meshing causes image defects such as pitch unevenness. In addition, problems such as deterioration in efficiency due to idling torque for ensuring the operation of the planetary gear occur. Further, since the motor is normally / reversely rotated at the time of connection / release of the drive, it is not suitable for a configuration in which the photosensitive member and the developing device are simultaneously driven by one motor.
[0006]
For this reason, in the development driving of the conventional in-line color image forming apparatus, a mechanical clutch excellent in cost and reliability that can be intermittently driven while the photosensitive member is rotating has not been used.
[0007]
Therefore, the present invention is particularly effective in an in-line color image forming apparatus, and is a driving apparatus that employs a small and low-cost mechanical clutch that can reliably interrupt a relatively large torque even when the driving side is rotating. The purpose is to provide.
[0008]
[Means for Solving the Problems]
  To solve the above problemsThe present inventionThe typical configuration of the electrophotographic photoreceptor and developmentrollerHavepluralProcess cartridgeHaveIn a drive device used in a color image forming apparatus,( i ) Motor and ( ii ) A switching member movably provided;(Iii) a plurality of clutches for controlling rotation and stop of the developing roller, and a driving component for transmitting a driving force from the motor;A rotating shaft for transmitting the driving force to the developing roller;The drive component andBy meshingRotate the same,Of the rotating shaftA drive-side engagement component movable in the axial direction;AboveA driven-side engaging part that is fixed to a rotating shaft and engages with the driving-side engaging part; an elastic member that urges the driving-side engaging part in a direction to engage with the driven-side engaging part; and the drive Move the side engagement parts in the axial direction,Between the driving side engaging part and the driven side engaging part.Control means for engaging and releasing,A lever member having a cam portion that rotates around the rotation shaft is provided. The lever member is rotated by the movement of the switching member, and the driving side engaging component is moved in the axial direction by the cam portion. Control means;HaveThe drive-side engagement component and the driven-side engagement component have a plurality of drive transmission surfaces inclined in the direction of biting into each other when engaged, and the drive transmission surfaces are symmetrical with respect to the rotation center. The arranged clutch, andThe switching memberBy movingRotating the plurality of lever members provided in the plurality of process cartridges;Rotate and stop the developing rollerIt is characterized by that.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of a driving device and a color image forming apparatus according to the present invention will be described with reference to the drawings. 1 is a cross-sectional view of a color image forming apparatus according to the present embodiment, FIG. 2 is a cross-sectional view of a process cartridge, FIG. 3 is a perspective view of the process cartridge, and FIG. 4 shows a mounting method of the process cartridge to the color image forming apparatus. FIG. 5 is a partial sectional view showing a positioning portion of a process cartridge for a color image forming apparatus, FIG. 6 is a partial sectional view showing a positioning portion of the process cartridge for a color image forming apparatus, and FIG. FIG. 8 is a cross-sectional view of the process cartridge in a state where black separation is released and other colors are separated, FIG. 9 is a perspective view of an operation switching mechanism, and FIG. 10 is a perspective view of a drive unit for driving the cartridge. 11 is a perspective view showing a mechanical clutch, FIG. 12 is a schematic view showing the state of the clutch during full-color recording, and FIG. It is a schematic diagram showing a state of the recording time of the clutch.
[0010]
[overall structure]
First, the overall configuration of the color image forming apparatus will be outlined with reference to FIG. FIG. 1 is a longitudinal sectional view showing the entire configuration of a full-color laser beam printer A which is an embodiment of a color image forming apparatus.
[0011]
As shown in FIG. 1, the color image forming apparatus A includes four photosensitive drums 1a, 1b, 1c, and 1d arranged in parallel in the vertical direction. The photosensitive drum 1 is driven to rotate counterclockwise in FIG. 10 by the driving means shown in FIG.
[0012]
A charging device 2 (2a, 2b, 2c, 2d) for uniformly charging the surface of the photosensitive drum 1 in order according to the rotation direction, and a laser beam is irradiated around the photosensitive drum 1 based on image information. A scanner unit 3 (3a, 3b, 3c, 3d) for forming an electrostatic latent image on the drum 1, and a developing device 4 (4a, 4b, 4c, 4d) for developing the toner image by attaching toner to the electrostatic latent image ) (Developing unit), electrostatic transfer device 5 that transfers the toner image on the photosensitive drum 1 to the transfer material S, and cleaning device 6 (6a, 6) that removes transfer residual toner remaining on the surface of the photosensitive drum 1 after transfer. 6b, 6c, 6d) and the like are provided.
[0013]
Here, the photosensitive drum 1, the charging device 2, the developing unit 4, and the cleaning device 6 are integrally formed as a cartridge to form a process cartridge 7.
[0014]
Hereinafter, the photosensitive drum 1 will be described in detail.
[0015]
The photoconductor drum 1 is configured by applying an organic photoconductive layer (OPC photoconductor) to the outer peripheral surface of an aluminum cylinder having a diameter of 30 mm, for example. Both ends of the photosensitive drum 1 are rotatably supported by a support member, and a driving force from a driving motor (not shown) is transmitted to one end, so that the photosensitive drum 1 is rotated counterclockwise. The
[0016]
As the charging device 2, a contact charging type can be used. The charging member is a conductive roller formed in a roller shape. The roller is brought into contact with the surface of the photosensitive drum 1 and the surface of the photosensitive drum 1 is made uniform by applying a charging bias voltage to the roller. To be charged.
[0017]
The scanner unit 3 is arranged in a substantially horizontal direction of the photosensitive drum 1, and image light corresponding to an image signal is rotated at high speed by a scanner motor (not shown) by a laser diode (not shown), and a polygon mirror 9 (9a, 9b). , 9c, 9d). The image light reflected by the polygon mirror 9 selectively exposes the surface of the charged photosensitive drum 1 through the imaging lens 10 (10a, 10b, 10c, 10d) to form an electrostatic latent image. It is composed. As shown in FIG. 5, the scanner unit 3 is formed to be longer than the pitch between the left and right side plates in the longitudinal direction, and is attached so that the protruding portion 33 protrudes from the opening hole 35 of the side plate 32 to the outside. In this case, the scanner unit is pressed by a compression spring 36 with a force of about 10 N downward by about 45 ° indicated by an arrow. Thereby, it presses against abutment reliably and is positioned.
[0018]
The developing unit 4 includes toner containers 41 (41a, 41b, 41c, and 41d) that respectively store yellow, magenta, cyan, and black toners, and the toner in the toner container 41 is supplied to the toner supply roller 42 by a feeding mechanism 42. The toner is applied to the outer periphery of the developing roller 40 that rotates in the clockwise direction in the figure by the toner supply roller 43 that rotates clockwise in FIG. 2 and the developing blade 44 that is pressed against the outer periphery of the developing roller 40 in FIG. Apply charge.
[0019]
Then, by applying a developing bias to the developing roller 40 facing the photosensitive drum 1 on which the latent image is formed, toner development is performed on the photosensitive drum 1 in accordance with the latent image.
[0020]
An electrostatic transfer belt 11 that circulates so as to face and contact all the photosensitive drums 1a, 1b, 1c, and 1d is disposed. The electrostatic transfer belt 11 is 10¹¹-10¹⁴It is composed of a film-like member having a volume resistivity of Ω · cm and a thickness of about 150 μm. This electrostatic transfer belt 11 is supported by a roller with four axes in the vertical direction, and circulates and moves so that the transfer material S is electrostatically attracted to the outer peripheral surface on the left side in the drawing so that the transfer material S contacts the photosensitive drum 1. To do. As a result, the transfer material S is conveyed to the transfer position by the electrostatic transfer belt 11, and the toner image on the photosensitive drum 1 is transferred.
[0021]
A transfer roller 12 (12a, 12b, 12c, 12d) is arranged in parallel at a position in contact with the inside of the electrostatic transfer belt 11 and facing the four photosensitive drums 1a, 1b, 1c, 1d. A positive charge is applied from the transfer roller 12 to the transfer material S via the electrostatic transfer belt 11, and the electric field generated by this charge causes the transfer material S in contact with the photosensitive drum 1 to be transferred onto the photosensitive drum 1. A negative toner image is transferred.
[0022]
The electrostatic transfer belt 11 is a belt having a circumferential length of about 700 mm and a thickness of 150 μm. The belt is stretched around four rollers, a driving roller 13, driven rollers 14 a and 14 b and a tension roller 15, and rotates in the direction of the arrow in the figure. As a result, the above-described electrostatic transfer belt 11 circulates and the toner image is transferred while the transfer material S is conveyed from the driven roller 14a side to the drive roller 13 side.
[0023]
The feeding unit 16 feeds and conveys the transfer material S to the image forming unit, and a plurality of transfer materials S are stored in the feeding cassette 17. At the time of image formation, the feeding roller 18 (half-moon roller) and the registration roller pair 19 are driven and rotated according to the image forming operation to separate and feed the transfer material S in the feeding cassette 17 one by one, and at the front end of the transfer material S Struck the registration roller pair 19, stopped once, formed a loop, and synchronized with the rotation of the electrostatic transfer belt 11 and the image writing position, and fed to the electrostatic transfer belt 11 by the registration roller pair 19. .
[0024]
The fixing unit 20 fixes the toner images of a plurality of colors transferred to the transfer material S, and includes a rotating heating roller 21a and a pressure roller 21b that presses and applies heat and pressure to the transfer material S. Consists of.
[0025]
That is, the transfer material S onto which the toner image on the photosensitive drum 1 has been transferred is conveyed by the fixing roller pair 21 when passing through the fixing unit 20, and is given heat and pressure by the fixing roller pair 21. As a result, the toner images of a plurality of colors are fixed on the surface of the transfer material S.
[0026]
As an image forming operation, the process cartridges 7a, 7b, 7c, and 7d are sequentially driven in accordance with the recording timing, and the photosensitive drums 1a, 1b, 1c, and 1d are rotated counterclockwise in accordance with the drive. Driven. Then, the scanner units 3 corresponding to the respective process cartridges 7 are sequentially driven. By this driving, the charging roller 2 imparts a uniform charge to the circumferential surface of the photosensitive drum 1, and the scanner unit 3 exposes the circumferential surface of the photosensitive drum 1 according to the image signal to perform photosensitive drum 1. An electrostatic latent image is formed on the peripheral surface. The developing roller 40 in the developing unit 4 forms (develops) a toner image on the peripheral surface of the photosensitive drum 1 by transferring the toner to the low potential portion of the electrostatic latent image.
[0027]
At the timing when the tip of the toner image formed on the peripheral surface of the photosensitive drum 1a on the most upstream side in the conveyance direction of the transfer material S is rotated and conveyed to a point facing the electrostatic transfer belt 11, the transfer material is transferred to the opposite point. The registration roller pair 19 starts rotating so that the recording start positions of S coincide with each other, and feeds the transfer material S to the electrostatic transfer belt 11.
[0028]
The transfer material S is pressed against the outer periphery of the electrostatic transfer belt 11 so as to be sandwiched between the electrostatic adsorption roller 22 and the electrostatic transfer belt 11, and a voltage is applied between the electrostatic transfer belt 11 and the electrostatic adsorption roller 22. By applying the charge, charge is induced in the transfer material S that is a dielectric and the dielectric layer of the electrostatic transfer belt 11, and the transfer material is electrostatically attracted to the outer periphery of the electrostatic transfer belt 11. As a result, the transfer material S is stably adsorbed to the electrostatic transfer belt 11 and conveyed to the most downstream transfer unit.
[0029]
While being conveyed in this way, the toner image on each photoconductive drum 1 is sequentially transferred to the transfer material S by an electric field formed between each photoconductive drum 1 and the transfer roller 12.
[0030]
The transfer material S to which the toner images of four colors are transferred is separated from the electrostatic transfer belt 11 by the curvature of the belt driving roller 13 and is carried into the fixing unit 20. After the toner image is thermally fixed by the fixing unit 20, the transfer material S is discharged out of the main body by the discharge roller pair 23 with the image surface facing down from the discharge unit 24.
[0031]
[Process cartridge]
The process cartridge will be described in detail with reference to FIGS. 2 and 3 show a main cross section and a perspective view of the process cartridge 7 containing toner. The yellow, magenta, cyan, and black process cartridges 7a, 7b, 7c, and 7d have the same configuration.
[0032]
The process cartridge 7 develops an electrostatic latent image on the photosensitive drum 1 and a drum-shaped electrophotographic photosensitive member, that is, the photosensitive drum 1, which is an image carrier, a photosensitive drum unit 50 including a charging unit and a cleaning unit. The developing unit 4 has a developing roller 40 as developing means.
[0033]
In the photosensitive drum unit 50, the photosensitive drum 1 is rotatably attached to the cleaning frame 51 via bearings 31 (31a, 31b). On the periphery of the photosensitive drum 1, there are a primary charging means 2 for uniformly charging the surface of the photosensitive drum 1 and a cleaning blade 60 for removing the developer (toner) remaining on the photosensitive drum. Has been placed. A toner feeding mechanism 52 is provided in the vicinity of the cleaning blade 60, and the toner feeding mechanism 52 transmits the driving force of a driving motor (not shown) to one end at the rear of the drawing, so that the photosensitive drum 1 is in an image forming operation. Accordingly, it is driven to rotate counterclockwise in the figure. The residual toner removed from the surface of the photosensitive drum 1 by the cleaning blade 60 is sequentially sent to a waste toner chamber 53 provided behind the cleaning frame by a toner feeding mechanism 52.
[0034]
The developing unit 4 includes a developing roller 40 that contacts the photosensitive drum 1 and rotates in the arrow Y direction, a toner container 41 that contains toner, and a developing frame 45. The developing roller 40 is rotatably supported by a developing frame 45 via a bearing member, and on the circumference of the developing roller 40, a toner supply roller 43 and a developing blade which are in contact with the developing roller 40 and rotate in the arrow Z direction. 44 are arranged respectively. Further, a feed mechanism 42 for stirring the toner contained in the toner container 41 and transporting it to the toner supply roller 43 is provided.
[0035]
The developing unit 4 is swingable with respect to the photosensitive drum unit 50 by a pin 49a around a support shaft 49 provided on each of bearing members 47 and 48 attached to both ends of the developing unit 4. The suspension structure is supported by. When the developing unit 4 is in the state of the process cartridge 7 alone (not attached to the printer main body), the developing unit is pressed by the pressure spring 54 so that the developing roller 40 comes into contact with the photosensitive drum 1 by a rotational moment about the support shaft 49. 4 is always energized. Further, the toner container 41 of the developing unit 4 is integrally provided with a rib 46 for contacting a separating means (described later) of the printer main body A when the developing roller 40 is separated from the photosensitive drum 1.
[0036]
[Driver]
Next, an operation mechanism when the process cartridge 7 is mounted on the printer main body A will be described. In FIG. 4, for easy understanding of the configuration, a process cartridge 7 (see FIG. 2) in which the charging unit 2, the developing unit 4, and the cleaning device 6 are integrated is composed of only the photosensitive drum 1 and the bearing 31. Simplified.
[0037]
As described above, when the process cartridge 7 is in a single state, the developing roller 40 is always in contact with the photosensitive drum 1 as shown in FIG. The process cartridge 7 is mounted on the printer main body A by inserting a bearing 31 for supporting the photosensitive drum 1 along the first guide groove 34 from the direction of the arrow as shown in FIG. As shown in FIG. 6, the position of the process cartridge 7 is determined by pressing the bearing 31 against the abutting surfaces 37 and 38 of the guide groove 34.
[0038]
As shown in FIG. 5, a shaft 39 is crimped on the left and right side plates 32, a torsion coil spring 30 is supported on the shaft 39, and an end portion 30 a is fitted and fixed in a hole 32 a of the left and right side plates 32. In the state where the process cartridge 7 is not present, the torsion coil spring 30 is restricted in the rotational direction by the bending raising 32b from the left and right side plates 32. When the process cartridge 7 is inserted, the torsion coil spring 30 rotates counterclockwise in the counterclockwise direction, and when it moves over the bearing 31, it is positioned as shown in FIG. The process cartridge 7 is pressed into the printer body.
[0039]
At this time, the developing roller 40 is separated from the photosensitive drum 1 against the urging force of the developing unit 4 as shown in FIGS. A separation plate 80 is disposed as a separation means for this purpose. Separating plates 80 (80a, 80b, 80c, 80d) are provided to push up the ribs 46a, 46b, 46c, 46d provided in the developing units 4 (4a, 4b, 4c, 4d) for yellow, magenta, cyan, and black. Each is provided.
[0040]
The cam 93 is rotated by the driving means shown in FIG. 9 and the separation plate 80 is pushed up by the cam 93. The separation position where the developing roller 40 is separated from the photosensitive drum 1, and the separation plate 80 is pushed up by the cam 93. Is in a state where the developing roller 40 is released, and is provided so as to be movable to a developing position where the developing roller 40 is brought into contact with the photosensitive drum 1. Only when the developing operation is performed, the push-up of the separation plate 80 is released, and the developing unit 4 is moved to the developing position.
[0041]
Here, the structure can be made relatively simple by limiting the operation modes of pushing up and releasing the spacing plate 80. That is, the standby state in which the yellow, magenta, cyan, and black color separation plates 80 are pushed up (FIG. 1), and the full color state in which the push-up of the yellow, magenta, cyan, and black color separation plates 80 is released (FIG. 7). , And yellow, magenta, and cyan, so that the three states of the monocolor state (FIG. 8) in which the spacer plate 80 is pushed up can be selected.
[0042]
In FIG. 9, there are two types of separation plates, black 80d and color 80z, in which 80a, 80b, and 80c are integrated, and a cam 93 that moves these has two types of profiles corresponding to each separation plate. As a result, the mode switching described above can be performed.
[0043]
The drive device for driving the cartridge branches from a drive motor 100 provided for each color as shown in FIG. 10 into a series 101 for driving the photosensitive drum 1 and a series 102 for driving the developing roller 40. A clutch CL is provided on the side to switch the rotation stop of the developing roller 40 when the photosensitive drum rotates once.
[0044]
With this configuration, since the driving of the photosensitive drums 1 for each color can be controlled independently, it is possible to take control that always reduces the color misregistration that is a problem in the inline-type full-color image forming apparatus. Further, it is not necessary to provide a separate motor for developing driving, and the cost can be reduced.
[0045]
Next, details of the clutch CL of the drive device will be described with reference to FIG.
[0046]
A gear 111 serving as a drive component that meshes with the motor 100 is rotatable and axially positioned with respect to the driven-side rotating shaft 118 by a fixing member (not shown). The inner side of the gear 111 is greatly thinned, and the inner periphery of the sliding boss 111a near the center is a positioning and sliding surface for the driven side rotating shaft 118, and the outer periphery is the positioning and sliding of the driving side engaging component 113. It becomes a surface. Similarly, there are four detents 111b in the vicinity of the inner periphery of the gear 111, which serve as detents for the drive-side engagement component 113.
[0047]
The drive-side engaging component 113 is slidably supported by fitting the inner peripheral surface 113a with the outer peripheral portion of the sliding boss 111a of the gear 111, and at the same time, the rotation stop 113b provided on the outer peripheral portion is provided with the gear 111. The same rotation as the gear 111 is achieved by engaging with the non-rotating stopper 111b. On the other hand, the engagement part 113 has four protrusions 113c, and when these engage with the protrusions 114c of the engagement part 114 on the driven side, the rotation can be transmitted.
[0048]
The drive transmission surface of the protrusion 113c is formed so as to be inclined in the direction of biting into the counterpart component by rotation. As a result, even when the clutch is engaged during rotation, the clutch can be reliably engaged, and even if a large torque is applied, tooth skipping does not occur. Further, by connecting the drive transmission surfaces with a gentle slope, it is possible to engage smoothly even when the clutch is connected during rotation.
[0049]
An end face on the driven side of the driving side engaging component 113 has a release portion 115 and a sliding portion 113d that rotates and slides. Further, the engaging component 113 is always urged in the direction of the driven-side engaging component 114 by a coil spring 112 as an elastic member. Since the components in contact with both ends of the coil spring 112 rotate the same, there is no problem with the end sliding of the spring or malfunction due to a change in the winding diameter.
[0050]
In the driven side engaging component 114, the rotating shaft 118 and the parallel pin 119 are fitted and fixed to the inner peripheral surface 114a and the groove 114b. Further, there are four protrusions 114c, which transmit rotation when they engage with the protrusions 113c of the engagement component 113 on the driven side. The drive transmission surface of the protrusion 114c is inclined in the same direction as the counterpart component 113c, and the drive transmission surfaces are connected by a gentle slope.
[0051]
The driving side engaging member 113, the driven side engaging member 114, and the coil spring 112 are included inside the gear 111. As a result, space can be effectively used to make it compact, and the driving force transmitted from the tooth surface is transmitted to the inside as it is, so there is no twisting or falling force on the engaging parts, making it easy to ensure the strength of the parts. Torque can be transmitted.
[0052]
The rotation shaft 118 is rotatably supported with respect to the frame 120 of the drive unit via the bearing member 117, and transmits the rotation from the gear 121 fixed to the end portion to the developing drive portion of the cartridge. The bearing member 117 is fixed to the frame 120 of the driving unit, and has two sliding portions 117a having an anti-rotation and positioning function on the outer peripheral portion and slidable in the axial direction, and a cylindrical surface 117b that rotates and slides. It has a sliding part.
[0053]
The lever member 116 rotates by fitting with the sliding portion 117b of the bearing member 117, and the lever portion 116a is operated by a switching member 91 described later. The lever member 116 has a cam portion 116c, which is in contact with the cam portion 115c of the release member 115 to control the axial position. Further, a plurality of cam portions 115c and 116c are provided symmetrically with respect to the rotation center. Thereby, it is possible to prevent malfunction and increase in operation resistance due to the tilt of the release member 115.
[0054]
The release member 115 is supported so that its inner sliding portion 115a fits with the sliding portion 117a of the bearing member 117, and its rotation is restricted and movable in the axial direction. The cam portion 115c has a shape corresponding to the cam portion 117c of the lever. The cam portion 115c abuts on the cam portion 115c to determine the axial position, and at the same time, the sliding portion 115b on the opposite side of the cam contacts the drive-side engagement component 113. This will determine the position of this.
[0055]
That is, in a state where the crest and crest of the cam portion 116c of the lever member 116 and the cam portion 115c of the release member 115 are combined, the release member 115 is pushed out in the direction of the gear 111, and the sliding portion 115b is driven to the drive side engagement member. The driving side engaging member 113 is pulled away from the driven side engaging member 114 against the spring 112 in contact with the sliding portion 113d of 113, so that a so-called clutch is disengaged.
[0056]
When the motor 100 rotates in this state, the sliding portions 113d and 115b slide, but the loss due to sliding resistance is not a problem because the clutch is disengaged and there is no load on the driven side.
[0057]
On the other hand, when the lever member 116 is turned and the crests and valleys of the cam portion 116c of the lever member 116 and the cam portion 115c of the release member 115 are combined, the release member 115 is moved in the direction of the driven gear 121 and driven. The side engaging member 113 is pressed by the elastic force of the spring 112 and meshes with the driven side engaging member 114, and the clutch is connected to transmit the rotation. When the engagement member is completely engaged, the sliding portions 113d and 115b are almost slid by setting so that a gap is generated between the drive side engagement member 113 and the release member 115 and the lever member 116. No load is generated and there is almost no decrease in efficiency.
[0058]
The clutch CL may be configured such that the driving side and the driven side are reversed.
[0059]
As shown in FIGS. 12B and 13B, the cam shapes of the lever member 116 and the release member 115 are made different for black and other colors. In other words, the black cam has a Mt. Fuji shape, and at the home position, the peak of the peak contacts the peak and the clutch is disengaged, and the clutch is connected no matter which direction the lever is turned. The cam shape of the other color has a slope similar to that for black on one side, but the other side is a flat portion having the same height as the apex.
[0060]
At the home position, the clutch is disengaged, and when the lever is turned in the direction in which the cam peaks and troughs come into contact with each other (FIG. 12 (b)), the clutch remains disengaged even when turned to the opposite side ( FIG. 13B).
[0061]
With this configuration, it is possible to easily set a full-color print state in which all the clutches CL are connected and a mono-color state in which only the black clutch CLd is connected on the basis of the home position.
[0062]
As shown in FIG. 11, the development driving clutch CL and the cam 93 that moves the separation plate 80 can be moved by moving the switching member 91 up and down by a single motor 90. The load resistance when operating the switching member 91 is maximized when all four clutches CL are disengaged after completion of full color printing.
[0063]
On the other hand, by providing a spring 122 that pulls the switching member 91 downward as shown in FIG. 12A, the switching member 91 that is moving to the uppermost position at the end of full color printing is pulled down with a strong spring force. It is possible to reduce the load when the clutches CL for all colors are disengaged. This spring force is also effective in reducing the load when the separating cam 93 is rotated at the end of printing to separate the developing rollers for all colors.
[0064]
On the other hand, at the end of mono-color printing, since the spring force with respect to the switching member 91 moving to the lowermost portion is small as shown in FIG. 13A, the increase in load when the black clutch CLd is disengaged is small. Further, by setting the spring so that the spring force becomes zero in the vicinity of the home position position, it is possible to make an effective setting both when the clutch CL for all colors is disengaged and when only the black clutch is disengaged.
[0065]
Further, as shown in FIG. 12B and the like, the load is evenly distributed by making the slope of the cam used when disengaging all the clutches CL looser than the slope when disengaging only the black clutch CLd. be able to.
[0066]
[Operation]
When the process cartridge 7 is mounted on the printer main body A, the developing drive and separation device on the main body side is at the home position, and the switching member 91 is accurately positioned by a sensor (not shown). At this time, the separation plates 80 for all colors of yellow, magenta, cyan, and black are pushed up, and the ribs 46 provided on the developing unit 4 ride on the separation plate 80 along the insertion operation of the process cartridge 7. The developing roller 40 is separated from the photosensitive drum 1 by a predetermined gap.
[0067]
This separated state is always maintained when the power is turned off and when development is not performed. Accordingly, even when the process cartridge 7 is mounted and not used for a long time, the developing roller 40 is always separated from the photosensitive drum 1, so that the developing roller 40 is in contact with the photosensitive drum 1 for a long time. By doing so, it is possible to reliably prevent permanent deformation of the roller layer.
[0068]
The recording operation will be described separately for full-color printing and mono-color printing.
[0069]
In the case of full-color printing, when a recording operation is started by a print signal, all the motors 100 that drive the process cartridge and the drive motor for the transfer belt rotate. At this time, the switching member 91 is at the home position, all the clutches CL are disengaged, and all the developing rollers 40 do not rotate.
[0070]
Next, as shown in FIG. 12 (a), the stepping motor 90 rotates clockwise in the drawing to the first stage and raises the switching member 91 to the first stage in the upward direction. 116 is rotated by an angle θ1, and as shown in FIG. 12B, all the release members 115 and the driving side engaging members 113 are moved to the right side in the drawing to engage with the driven side engaging members 114 and the clutch is connected. All the developing rollers 40 are rotated.
[0071]
Here, when the cartridge driving motor 100 is rotated after turning the stepping motor 90 to the first stage, the impact load when the clutch is engaged is reduced, but for the purpose of shortening the rotation time of the developing roller 40 It is disadvantageous.
[0072]
Next, when the stepping motor 90 rotates clockwise to the second stage, the switching member 91 rises to the second stage in the upward direction, and the lever member 116 rotates to the angle θ2 (not shown). At this time, since the position of the release member 115 is in a position where the engagement of the driving side engaging component 113 and the engaging component 114 is maintained (FIG. 12C), all the developing rollers 40 remain rotated. On the other hand, the separation cam 93 rotates to release the color and black separation plates 80z and 80d from being pushed up, and all the developing rollers 40 come into contact with the photosensitive drum 1 to be in a recordable state.
[0073]
After the end of recording, the developing roller 40 is separated from the photosensitive drum 1 by returning the stepping motor 90 to the first stage. Then, by rotating the stepping motor 90 to the initial state, all the clutches CL are disengaged to stop the rotation of the developing roller 40, and the cartridge driving motor 100 and the transfer belt driving roller are stopped. The rotation for returning the stepping motor 90 from the first stage to the initial state may be performed after the cartridge driving motor 100 and the transfer belt driving roller are stopped.
[0074]
In the case of mono-color printing, when a recording operation is started by a print signal, all the motors 100 that drive the process cartridge and the drive motor for the transfer belt rotate. At this time, since all the clutches CL are disengaged, the developing roller 40 does not rotate.
[0075]
Next, as shown in FIG. 13 (a), when the stepping motor 90 rotates counterclockwise in the drawing to the first stage and the switching member 91 is lowered to the first stage in the downward direction, the lever members of all the clutch CLs. 116 rotates by an angle θ3, and only the black clutch CLd is connected and the other clutches CLa to CLc remain disconnected as shown in FIG. 13B, so that only the black developing roller rotates.
[0076]
Here, when the cartridge driving motor 100 is rotated after turning the stepping motor 90 to the first stage, the impact load when the clutch is connected is reduced, but it is disadvantageous for the purpose of shortening the rotation time of the developing roller. It is.
[0077]
Next, when the stepping motor 90 rotates counterclockwise to the second stage, the switching member 91 descends to the second stage in the downward direction, and the lever member 116 rotates to the angle θ4 (not shown). At this time, as shown in FIG. 13C, since the position of the black release member 115 is maintained in the first stage, the black developing roller 40 remains rotated. On the other hand, the separation cam 93 is rotated to release the push-up operation by the black separation plate 80d, and the black developing roller 40 comes into contact with the photosensitive drum 1 to be in a recordable state.
[0078]
After the end of recording, the developing roller 40 is separated from the photosensitive drum 1 by returning the stepping motor 90 to the first stage. Then, the rotation of the developing roller 40 is stopped by rotating the stepping motor 90 to the initial state, and the cartridge driving motor 100 and the transfer belt driving roller are stopped. The rotation for returning the stepping motor 90 from the first stage to the initial state may be performed after the cartridge driving motor 100 and the transfer belt driving roller are stopped.
[0079]
In the process of forming an image in this manner, before the electrostatic latent image is formed by the scanner unit 3, a pre-rotation is performed in order to apply a uniform charge to the peripheral surface of the photosensitive drum 1. Then, after developing the toner image, a post-rotation process or the like is performed in order to eliminate the potential on the circumferential surface of the photosensitive drum. During the pre-rotation and post-rotation, the developing roller 40 is separated from the photosensitive drum, so that toner is not wasted due to fogging, and the photosensitive drum 1 is rubbed against the developing roller 40. It is possible to reduce the surface layer from being scraped.
[0080]
Further, the standby state in which the separation plates 80 for all colors are pushed up (FIG. 1), the full color state in which the separation of the separation plates 80 for all colors is released (FIG. 7), and the separation plates 80 for only the three colors yellow, magenta and cyan. By consolidating the modes so that the three states of the mono color to be pushed up (FIG. 8) can be selected, the component configuration and control can be simplified.
[0081]
Further, by applying an elastic force to the switching member 91 by the spring 122 so as to urge the plurality of clutches CL in the releasing direction, the operating torque is reduced, and the cost of electric parts such as motors and mechanical parts can be reduced. It becomes possible.
[0082]
【The invention's effect】
  As explained above,According to the present invention,A drive device employing a small and low-cost mechanical clutch capable of reliably interrupting a relatively large torque even when the drive side is rotating can be obtained.
[0083]
  Also,Control of clutch operation can be simplified.
[0085]
In particular, by providing a plurality of driving devices in the color image forming apparatus, it is possible to provide an in-line color image forming apparatus with high quality and low cost.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a color image forming apparatus according to an embodiment.
FIG. 2 is a cross-sectional view of a process cartridge.
FIG. 3 is a perspective view of a process cartridge.
FIG. 4 is a perspective view illustrating a method of mounting a process cartridge on a color image forming apparatus.
FIG. 5 is a partial cross-sectional view showing a positioning portion of a process cartridge for a color image forming apparatus.
FIG. 6 is a partial cross-sectional view showing a positioning portion of a process cartridge for a color image forming apparatus.
FIG. 7 is a cross-sectional view showing a state in which the process cartridge is released.
FIG. 8 is a cross-sectional view showing a process cartridge in a state where black separation is released and other colors are separated.
FIG. 9 is a perspective view showing an operation switching mechanism.
FIG. 10 is a perspective view of a drive unit that drives a cartridge.
FIG. 11 is a perspective view showing a mechanical clutch.
FIG. 12 is a schematic diagram showing a state of a clutch during full-color recording.
FIG. 13 is a schematic diagram showing a state of a clutch during mono-color recording.
[Explanation of symbols]
A: Full color laser beam printer
CL: Clutch
S: Transfer material
1 ... Photoconductor drum
2 ... Charging device
3 Scanner unit
4 ... Developing unit
5 ... Electrostatic transfer device
6 ... Cleaning device
7 Process cartridge
9 ... Polygon mirror
10… Imaging lens
11… Electrostatic transfer belt
12… Transfer roller
13… Drive roller
14a, 14b ... driven roller
15… Tension roller
16… Feeding department
17… Feed cassette
18… feed roller
19… Registration roller pair
20… Fixing part
21a ... Heating roller
21b… Pressure roller
22… Electrostatic adsorption roller
23… discharge roller pair
24… discharge section
30… Torsion coil spring
30a ... end
31… Bearing
32… Side plate
32a ... Hole
32b ... Bending up
33 ... Protrusions
34… Guide groove
35… opening hole
36… Compression spring
37… Abutting surface
38… Abutting surface
39… axis
40… Development roller
41 ... Toner container
42… Feed mechanism
43 ... Toner supply roller
44… Developer blade
45… Development frame
46… Ribs
47, 48… Bearing members
49… support shaft
49a… pin
50… Photoreceptor drum unit
51… Cleaning frame
52 ... Toner feed mechanism
53… Waste toner chamber
54… Pressure spring
60… Cleaning blade
80 ... spacing plate
80d for black
80z for color
91 ... Switching member
93… Cam
100… Motor
101, 102 ... series
111… Gear
111a ... sliding boss
111b ... non-rotating
112… Coil spring
113… Drive side engagement parts
113a ... Inner peripheral surface
113c ... projection
113d ... sliding part
114… engaging parts
114a ... Inner peripheral surface
114b ... groove
114c ... projection
115… Release member
115b ... sliding part
115c ... Cam part
116… Lever member
116a ... Lever part
116c… Cam part
117… Bearing member
117a ... sliding part
117b ... Cylindrical surface
118… Rotation axis
119… Parallel pin
120 ... frame
121… Gear
122… Spring

Claims (5)

In a driving device used in a color image forming apparatus having a plurality of process cartridges having an electrophotographic photosensitive member and a developing roller ,
( I ) motor and
( Ii ) a switching member movably provided;
(Iii) a plurality of clutches for controlling rotation and stop of the developing roller,
A driving component for transmitting a driving force from the motor;
A rotating shaft that transmits the driving force to the developing roller, and a driving side engaging component that rotates in the same direction by meshing with the driving component and is movable in the axial direction of the rotating shaft ;
The fixed to the rotating shaft, and the driven engaging part to be engaged with the driving-side engaging part,
An elastic member that urges the driving side engaging component in a direction to engage with the driven side engaging component;
Control means for moving the driving side engaging component in the axial direction to engage and release the driving side engaging component and the driven side engaging component, and rotate around the rotation axis. A control member that has a lever member having a cam portion, the lever member is rotated by the movement of the switching member, and the driving side engaging component is moved in the axial direction by the cam portion;
Have
The drive-side engagement component and the driven-side engagement component have a plurality of drive transmission surfaces inclined in the direction of biting into each other when engaged, and the drive transmission surfaces are symmetrical with respect to the rotation center. The arranged clutch, and
Have
A driving device characterized in that by moving the switching member , the plurality of lever members provided in the plurality of process cartridges are rotated to rotate and stop the developing roller .   The drive device according to claim 1, wherein the drive component is a gear, and the drive-side engagement component and the driven-side engagement component are included in the gear. In the plurality of process cartridges, and the cam portion included in the process cartridge of black, with different shape of the cam portion to which the process cartridge has another color, and full color print in the connected state all colors of the clutch, all colors 2. The drive device according to claim 1, wherein the three states of a standby state in which the clutch is disconnected and a monocolor state in which only the clutch of the black process cartridge is connected can be switched. The elastic force is applied to the switching member, and the plurality of clutches are biased in a direction in which the engagement between the driving side engaging component and the driven side engaging component is released. The drive device according to 1. A color image forming apparatus comprising the driving device according to claim 1 .

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