JP4830752B2 - Drive device - Google Patents

Description

  The present invention relates to a drive device, and more particularly to a drive device used in an image forming apparatus including a plurality of image forming units.

  In recent years, image forming apparatuses such as copying machines and printers capable of forming full-color images have become widespread. Among such image forming apparatuses capable of forming a full-color image, an image forming apparatus employing a method called a tandem method includes a plurality of developing devices and a plurality of photosensitive drums. Conventionally, in order to rotate the developing roller and the plurality of photosensitive drums included in the plurality of developing devices, a motor is provided for each developing roller and each of the photosensitive drums and is driven independently.

  However, there is an increasing demand for downsizing image forming apparatuses. In response to this requirement, there has been proposed an image forming apparatus in which a plurality of developing rollers and a photosensitive drum are rotated by a single motor. FIG. 12 is a configuration diagram of the driving device 200 of the image forming apparatus. Hereinafter, the driving device 200 will be described with reference to FIG. Note that symbols Y, M, and C shown in FIG. 12 mean members for yellow, magenta, and cyan. The same applies to the other drawings.

  The driving device 200 is a device for driving the developing device 201 (201Y, M, C), and includes a motor (not shown) and a transmission unit 200 ′. The transmission unit 200 ′ includes a motor gear 202 and gears 203 to 212. The developing devices 201Y, 201M, and 201C supply toner to a photosensitive drum (not shown) on which a latent image is formed, and form a toner image on the photosensitive drum. Therefore, each developing device 201Y, M, C includes a developing roller for supplying toner to the photosensitive drum.

  The motor gear 202 is connected to a motor (not shown) and is rotated by the power of the motor. The gears 203 to 211 transmit the power transmitted from the preceding gear to the subsequent gear, and play a role of branching the power transmission path into three. The gears 212Y, M, and C are connected to the developing rollers of the corresponding developing devices 201Y, M, and C, respectively, and are rotated by the power transmitted from the preceding gears 207, 208, and 211. As a result, the developing rollers of the developing devices 201Y, M, and C rotate.

  Incidentally, the driving device 200 has a problem that a large load is applied to the gear 204 at the moment when the driving of the developing devices 201Y, M, and C is started. This is because, at the start of driving of the developing devices 201Y, 201M, and 201C, the inertial force that keeps the gears stationary is applied collectively to the gear 204 located at the junction of the three power transmission paths. It is.

  As a device for solving the above problem, a driving device described in Patent Document 1 is known. In this drive device, an elastic member that suppresses the generation of noise by absorbing an impact at the time of meshing with one gear of a pair of gears meshed with each other is provided. Thereby, in the driving device 200 as described above, the load applied to the gear 204 can be reduced at the moment when the driving of the developing devices 201Y, M, and C is started.

However, in the drive device described in Patent Document 1, it is necessary to provide an elastic member for each gear. Therefore, there is a problem that the weight of each gear is increased and the transmission loss of power is increased.
JP-A-11-230313

  SUMMARY OF THE INVENTION An object of the present invention is to provide a drive device used in an image forming apparatus, which can reduce power transmission loss and reduce a load applied to a gear at the moment of starting rotation of a developing roller or the like. It is to be.

According to the present invention, in a driving device used in an image forming apparatus including a plurality of image forming units, a power source and a rotator included in each image forming unit are branched by dividing the power generated by the power source. A transmission unit that transmits power, and the transmission unit transmits power so that each rotating body starts rotating at different timings , and is provided to correspond to each of the image forming units, and A first rotating member that is rotated by the power generated by the power source, and a first rotating member that is provided to face each of the first rotating members and that is included in the corresponding image forming unit. In a state in which the second rotating member for transmitting power from the rotating member and the first rotating member are not rotating, the first rotating member is rotated in the rotational direction with respect to the second rotating member. Initial position return means for returning the position to an initial position, wherein the first rotating member and the second rotating member are at a predetermined angle from the initial position with respect to the second rotating member. When the first rotating member rotates, the first rotating member starts to rotate integrally, and the predetermined angle is different for each set of the first rotating member and the second rotating member, and the initial position returning means Is a spring having both ends fixed to the first rotating member and the second rotating member .

  According to the present invention, since the transmission unit starts transmitting power so that each rotating body starts to rotate at different timings, a large load is applied to the gear in the drive device at the start of rotation of each rotating body. Is suppressed. In the present invention, the rotating body refers to, for example, a developing roller or a photosensitive drum.

Moreover , it is possible to vary the rotation start timing of each second rotating member by varying the predetermined angle for each pair of the first rotating member and the second rotating member.

  In the present invention, a first protrusion is formed on the first rotating member, a second protrusion is formed on the second rotating member, and the first protrusion and the first protrusion The first rotating member and the second rotating member may be rotated together by contacting the second convex portion. Furthermore, in the present invention, the distance between the first convex portion and the second convex portion may be different for each set of the first rotating member and the second rotating member.

In the present invention, each second rotating member has the same shape, and the first rotating member and the second rotating member are made different by changing the fixing position of the spring for each second rotating member. The predetermined angle is preferably different for each set of rotating members. Since each 2nd rotation member has the same shape, the cost at the time of forming a 2nd rotation member is reduced.

  Hereinafter, a drive device according to an embodiment of the present invention will be described with reference to the accompanying drawings.

(Schematic configuration of image forming apparatus)
FIG. 1 is a configuration diagram of an image forming apparatus 1 on which a driving device according to the present invention is mounted. The image forming apparatus 1 is an electrophotographic color printer, and is configured to synthesize four-color images in a so-called tandem system. The image data is transmitted from an external computer or the like as an electrical signal separated into RGB (red, green, and blue) primary colors. This image data is further converted into YMCK (yellow, magenta, cyan, and black) reproduction colors. The

  The image forming apparatus 1 includes an image forming unit 10 (10Y, 10M, 10M) that forms a YMCK image including a photosensitive drum 11, a charging device 12, a laser scanning optical unit 13, a developing device 14, a residual toner cleaning device 15, and the like. 10C, 10K) are juxtaposed directly below the intermediate transfer belt 20. In each image forming unit 10, the laser scanning optical unit 13 receives the transfer of the YMCK image data, forms a latent image on the photosensitive drum 11, and forms a toner image by the developing device 14.

  The developing device 14 includes a developing roller 55, a supply screw 61, and a stirring screw 65 in order to form the toner image. The developing roller 55 carries the developer on the outer peripheral surface and conveys the developer to the developing area based on rotation. The supply screw 61 is rotatably disposed below the developing roller 55 and supplies the developer to the developing roller 55 while stirring / conveying the developer. The agitating screw 65 is rotatably disposed obliquely below the supply screw 61 and agitates / conveys the developer containing the replenished toner.

  The intermediate transfer belt 20 is stretched endlessly between a driving roller 21 and a driven roller 22 that applies tension, and is rotationally driven in the direction of arrow A by a rotational driving force transmitted from the driving roller 21. A primary transfer roller 25 is disposed on the inner surface side of the intermediate transfer belt 20 at a position facing each photosensitive drum 11.

  A secondary transfer roller 26 is disposed on the intermediate transfer belt 20 at a portion facing the driving roller 21. Further, a cleaning blade 27 for wiping residual toner comes into contact with the intermediate transfer belt 20 at a portion facing the driven roller 22, and the toner wiped by the blade 27 is stored in a waste bottle 28.

  An automatic paper feeder 30 that feeds the stacked sheets one by one is installed in the lower part of the image forming apparatus 1. Further, a fixing unit 35 for heat-fixing the toner is disposed immediately above the secondary transfer roller 26.

  A cartridge 19 containing replenishing toner is detachably installed above the intermediate transfer belt 20, and the toner is replenished to the developing device 14 at an appropriate timing.

  The toner images formed on the respective photosensitive drums 11 are sequentially primary-transferred onto the intermediate transfer belt 20 that is rotationally driven in the direction of arrow A, and four color images are combined. On the other hand, the sheets are fed one by one from the automatic sheet feeder 30 and the combined toner image is secondarily transferred from the intermediate transfer belt 20 by the secondary transfer roller 26. Thereafter, the sheet is conveyed to the fixing unit 35 to heat and fix the toner image, and is discharged from the discharge roller 36 onto the tray 2.

  Incidentally, in each image forming unit 10, the photosensitive drum 11, the charging device 12, and the cleaning device 15 are integrally formed into a cartridge and detachable from the image forming apparatus 1. The developing device 14 is also detachably installed on the image forming apparatus 1. Note that it is arbitrary which apparatus is incorporated in a cartridge that is detachably installed in the image forming apparatus 1. For example, the photosensitive drum 11, the charging device 12, the developing device 14, and the cleaning device 15 may be integrated into a cartridge.

(First Embodiment, Configuration of Drive Device)
FIG. 2 is a configuration diagram of the driving device 70 according to the first embodiment. The driving device 70 divides the power generated by the motor into three to power the developing roller 55, the supply screw 61, and the stirring screw 65 (each not shown) included in each of the developing devices 14Y, 14M, 14C. To communicate. Furthermore, when the driving device 70 starts driving the developing devices 14Y, 14M, and 14C at the same time, the driving device 70 transmits power so that the developing rollers 55 of the developing devices 14Y, 14M, and 14C start rotating at different timings. In order to realize this operation, the driving device 70 includes a motor 71 and a transmission unit 70 ′. The transmission unit 70 ′ includes a motor gear 72, gears 73 to 81, and a clutch unit 82 (82Y, M, C).

  The motor gear 72 is connected to the motor 71 and is rotated by the power of the motor 71. The gears 73 to 81 transmit the power transmitted from the preceding gear to the subsequent gear or clutch unit, and play a role of branching the power transmission path into three. Specifically, the gear 73 transmits the power transmitted from the motor gear 72 to the gear 74. The gear 74 branches the power transmitted from the gear 73 into two transmission paths of the gear 75 and the gear 79. The gear 75 transmits the power transmitted from the gear 74 to the gear 76. The gear 76 branches the power transmitted from the gear 75 into two transmission paths of the gear 77 and the gear 78. The gear 77 and the gear 78 transmit the power transmitted from the gear 76 to the clutch portion 82Y and the clutch portion 82M, respectively.

  The gear 79 transmits the power transmitted from the gear 74 to the gear 80. The gear 80 transmits the power transmitted from the gear 79 to the gear 81. The gear 81 transmits the power transmitted from the gear 80 to the clutch portion 82C. The clutch portions 82Y, 82M, 82C serve to transmit or block the power transmitted from the gears 77, 78, 81 to the developing roller 55, respectively. With the above configuration, the power generated by the motor 71 is transmitted to the developing roller 55 of the developing devices 14Y, 14M, 14C.

(Configuration of clutch part)
3 and 4 are exploded perspective views of the clutch portion 82. As described above, the clutch portions 82Y, 82M, 82C serve to transmit or block the power transmitted from the gears 77, 78, 81 to the developing roller 55, respectively. Further, the clutch units 82Y, M, C transmit power to the developing rollers 55 of the developing devices 14Y, 14M, 14C at slightly different timings when simultaneously starting the developing devices 14Y, 14M, 14C. To start. In order to realize such an operation, the clutch portion 82 includes a gear 83, a spring 84, and a rotating plate 85. The developing device 14 includes a shaft 87 connected to the developing roller 55 (not shown) and a rotating plate 86 connected to the shaft 87.

  The gear 83 is a disk that is provided so as to correspond to each of the developing devices 14Y, 14M, 14C, and is rotated by the power transmitted by the gears 73 to 81. On the side surface of the gear 83, teeth (not shown) for meshing with any of the teeth of the gears 77, 78, 81 are formed.

  The rotating plate 85 is provided to face the gear 83 and relays the transmission of power to the developing roller 55 of the corresponding developing device 14.

  The spring 84 is provided between the gear 83 and the rotating plate 85. A groove 83c and a hole 85c are formed in each of the gear 83 and the rotating plate 85. The spring 84 is fixed to the gear 83 and the rotating plate 85 by inserting the end of the spring 84 into the groove 83c and the hole 85c. The spring 84 serves to return the position of the gear 83 in the rotational direction relative to the rotating plate 85 to the initial position when the gear 83 is not rotating.

  On the main surface of the gear 83 on the rotating plate 85 side, two claw portions 83a and 83b protruding to the rotating plate 85 side are formed. Two claw portions 85a and 85b projecting to the gear 83 side are formed on the main surface of the rotating plate 85 on the gear 83 side. Since the gear 83 and the rotating plate 85 have such a structure, when the gear 83 rotates by a predetermined angle from the initial position, the claw portions 83a and b come into contact with the claw portions 85a and b, and the gear 83 and the rotating plate 85 and rotate together. As a result, the power from the motor 71 is transmitted to the rotating plate 85 via the gear 83.

  Further, on the main surface of the rotating plate 85 on the rotating plate 86 side, three claw portions 85d, e, and f projecting to the rotating plate 86 side are formed. A claw portion 86 a that protrudes toward the rotating plate 85 is formed on the main surface of the rotating plate 86 on the rotating plate 85 side. Since the rotary plate 85 and the rotary plate 86 have such a structure, any one of the claw portions 85d, e, and f and the claw portion 86a come into contact with each other, and the rotary plate 85 and the rotary plate 86 rotate together. . As a result, the power from the rotating plate 85 is transmitted to the developing roller 55 via the rotating plate 86 and the shaft 87.

  Here, as described above, the clutch portions 82Y, 82M, 82C, 82C, 82C, 82C, 82C, 82C, 82C, 82C, 82C, 82C, 82C, 82C, 82M Start transmitting power. Therefore, the predetermined angle is varied for each set of the gear 83 and the rotating plate 85 of each clutch portion 82Y, M, C. As described above, the predetermined angle is an angle at which the gear 83 must rotate with respect to the rotating plate 85 from the initial position before the gear 83 and the rotating plate 85 start to rotate integrally. In other words, the distance (play) between the claw part 83a and the claw part 85a and the play between the claw part 83b and the claw part 85b are made different for each set of the gear 83 and the rotating plate 85.

(First example of rotating plate)
Hereinafter, the timing at which the claw portions of the respective clutch portions 82Y, 82M, 82C are engaged will be described with reference to FIG. FIG. 5 is an explanatory diagram of a first example of a rotating plate for explaining the timing at which the claw portions of the clutch portions 82Y, 82M, 82C are engaged. Specifically, FIG. 5 shows the positional relationship between the claw portions 83a and 83b and the claw portions 85a and 85b when the gear 83 and the rotating plate 85 of each clutch portion 82Y, M, and C are in the initial positions. FIG.

  As shown in FIG. 5A, in the clutch portion 82Y, when the gear 83 and the rotary plate 85 are in the initial position, the claw portion 83a and the claw portion 85a are in contact with each other, and the claw portion 83b The claw portion 85b is in contact. As shown in FIG. 5 (B), in the clutch portion 82M, when the gear 83 and the rotating plate 85 are in the initial position relationship, between the claw portion 83a and the claw portion 85a and between the claw portion 83b and the claw portion 85b. 45 degree play is provided between the two. As shown in FIG. 5C, in the clutch portion 82C, when the gear 83 and the rotating plate 85 are in the initial position relationship, the claw portion 83b and the claw portion 85b are located between the claw portion 83a and the claw portion 85a. There is a 90-degree play between the two.

  As described above, since the play between the claw part 83a and the claw part 85a and the play between the claw part 83b and the claw part 85b are different for each of the clutch parts 82Y, M, and C, each gear 83 is Even if the rotation starts at the same time, the timing at which the rotation plate 85 starts to rotate is different for each of the clutch portions 82Y, 82M, 82C. Therefore, when the developing devices 14Y, 14M, 14C start driving simultaneously, the developing rollers 55 of the developing devices 14Y, 14M, 14C start to rotate at different timings. As a result, when the plurality of developing rollers 55 start to rotate at the same time, it is possible to prevent a large load from being applied to the gear 74 in the driving device 70. Specifically, as shown in FIG. 6, the load (torque) applied to the gear 74 increases stepwise. In FIG. 6, the vertical axis represents the torque applied to the gear 74, and the horizontal axis represents time.

(Second example of rotating plate)
FIG. 7 is an explanatory diagram of a second example of the rotating plate for explaining the timing at which the claw portions of the clutch portions 82Y, 82M, 82C are engaged. Specifically, FIG. 7 shows the positional relationship between the claw portions 83a and 83b and the claw portions 85'a and b when the gear 83 and the rotary plate 85 'of each clutch portion 82Y, M, and C are in the initial positions. FIG.

  The claw portions 85a and 85b shown in FIG. 5 all have the same central angle, whereas the claw portions 85′a and b shown in FIG. 7 have different central angles. This is because the play between the claw portions 83a, b and the claw portions 85'a, b is changed by changing the central angle of the claw portions 85'a, b.

  As shown in FIG. 5, when the central angles of the claw portions 85a and 85b are all the same, a plurality of the same shaped rotating plates 85 are produced, and the holes 85c are rotated to different positions for the respective clutch portions 82Y, M, and C. By forming on the plate 85, the rotating plate 85 can be obtained. Thereby, only one type of mold for molding the rotating plate 85 can be provided.

  On the other hand, as shown in FIG. 7, since the claw portions 85′a and b have different central angles, a plurality of molds for forming the rotating plate 85 ′ are required. Instead, the formation position of the hole 85′c can always be a fixed positional relationship with respect to one radius of the claw portions 85′a and b.

  Further, the rotating plate 85 (85 ′) and the rotating plate 86 rotate integrally when one of the three claw portions 85 (85 ′) d, e, and f is engaged with the claw portion 86a. The method of meshing between 85 (85 ′) and the rotating plate 86 is not limited to this. The rotating plate 85 (85 ') and the rotating plate 86 are preferably engaged with each other with as little play as possible. Accordingly, many claw portions may be formed on the main surface of the rotary plate 85 (85 ') or the rotary plate 86. Further, the rotating plate 85 (85 ') and the rotating plate 86 may be engaged with each other by a gear. Further, the rotating plate 86 can be omitted and the rotating plate 85 (85 ') can be directly connected to the shaft 87.

(Other variations)
In this embodiment, the driving device 70 is applied to the rotation of the developing roller 55, but the driving device 70 may be applied to the rotation of the photosensitive drum 11. It is also possible to apply the drive device 70 to the rotation of both the developing roller 55 and the photosensitive drum 11. Further, as shown in FIG. 8, the developing roller 55 and the photosensitive drum 11 can be rotated by a single motor 71. In this case, in the driving device 70 for rotating the developing roller 55, it is preferable that a clutch portion 74 ′ is provided instead of the gear 74. This is because there is a state in which the developing roller 55 is stopped while the photosensitive drum 11 is rotating. Thereby, the power consumption of the image forming apparatus 1 can be reduced in such a state.

(Second Embodiment)
FIG. 9 is a configuration diagram of the driving apparatus 100 according to the second embodiment. FIG. 10 is a block diagram of the electromagnetic clutch unit 101 (101Y, M, C) and the control unit 102.

  The driving device 100 is different from the driving device 70 in that the so-called electromagnetic clutch portions 101Y, M, and C are provided, whereas the driving device 70 is provided with the mechanical clutch portions 82Y, M, and C. Has differences. And each electromagnetic clutch part 101Y, M, C is connected to the control part 102, as shown in FIG.

  The electromagnetic clutch portions 101Y, 101M, and 101C are configured so that an electromagnetic force is applied between two rotating plates corresponding to the gear 83 and the rotating plate 85, so that the two rotating plates are in a contact state and a non-contact state. Is to switch. The control unit 102 is realized by a CPU, for example, and switches between the contact state and the non-contact state of the electromagnetic clutch units 101Y, M, and C.

  The operation of the electromagnetic clutch portions 101Y, 101M, 101C having the above configuration will be described with reference to FIG. FIG. 11 is a diagram illustrating an operation example of the electromagnetic clutch portions 101Y, 101M, 101C when the developing devices 14Y, 14M, 14C start to operate simultaneously.

  When the developing devices 14Y, 14M, 14C are in a stopped state, the control unit 102 controls the electromagnetic clutch units 101Y, 101M, 101C to be in a non-contact state. When the developing devices 14Y, 14M, 14C start operating, the control unit 102 switches to the contact state in the order of the electromagnetic clutch units 101Y, 101M, 101C, as shown in FIG. The switching interval is preferably about 100 ms. As a result, the timing at which the developing rollers 55 of the developing devices 14Y, 14M, 14C start to rotate is different. As a result, also in the driving device 100, as in the driving device 70, a large load is suppressed from being applied to the gear 74 in the driving device 100 when the plurality of developing rollers 55 start to rotate simultaneously.

  Further, as in the first embodiment, the driving device 100 may be applied to the rotation of the photosensitive drum 11. Further, it is possible to apply the driving device 100 to the rotation of both the developing roller 55 and the photosensitive drum 11. Further, it is possible to rotate the developing roller 55 and the photosensitive drum 11 by one motor 71.

1 is a configuration diagram of an image forming apparatus in which a driving device according to the present invention is mounted. It is a block diagram of the drive device which concerns on 1st Embodiment. It is a disassembled perspective view of a clutch part. It is a disassembled perspective view of a clutch part. It is explanatory drawing of the 1st example of the rotating plate for demonstrating the timing which the nail | claw part for every clutch part engages. It is the graph which showed the relationship between the torque concerning a gear, and time. It is explanatory drawing of the 2nd example of the rotating plate for demonstrating the timing which the nail | claw part for every clutch part engages. It is a block diagram of the modification of the said drive device. It is a block diagram of the drive device which concerns on 2nd Embodiment. It is a block diagram of an electromagnetic clutch part and a control part. It is a figure showing an example of operation of an electromagnetic clutch part when a development device starts operation simultaneously. It is a block diagram of the conventional drive device of an image forming apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 11 Photosensitive drum 14 Developing apparatus 55 Developing roller 61 Supply screw 65 Stirring screw 70,100 Drive apparatus 70 ', 100' Transmission part 71 Motor 72 Motor gear 73,74,75,76,77,78,79, 80, 81, 83 Gear 82, 74 'Clutch part 83a, b Claw part 83c Groove 84 Spring 85, 85', 86 Rotating plate 85a, b, d, e, f, 85'a, b, d, e, f 86a Claw part 85c Hole 101 Electromagnetic clutch part 102 Control part

Claims (4)

In a drive device used in an image forming apparatus including a plurality of image forming units,
Power source,
A transmission unit for transmitting power to each of the rotating bodies included in each image forming unit by branching the power generated by the power source;
With
The transmission unit is
Transmit power so that each rotating body starts rotating at different timings ,
A first rotating member that is provided to correspond to each of the image forming units and that is rotated by the power generated by the power source;
A second rotating member provided to face each of the first rotating members and transmitting power from the first rotating member to a rotating body included in the corresponding image forming unit;
Initial position returning means for returning the position of the first rotating member in the rotational direction with respect to the second rotating member to the initial position in a state where the first rotating member is not rotating;
Including
The first rotating member and the second rotating member rotate together when the first rotating member rotates by a predetermined angle from the initial position with respect to the second rotating member. Start to
The predetermined angle is different for each set of the first rotating member and the second rotating member,
The initial position return means is a spring having both ends fixed to the first rotating member and the second rotating member;
A drive device characterized by the above. A first protrusion is formed on the first rotating member;
A second protrusion is formed on the second rotating member,
The first rotating member and the second rotating member rotate together as a result of the first protruding portion and the second protruding portion coming into contact with each other;
The drive device according to claim 1 . The distance between the first convex portion and the second convex portion is different for each set of the first rotating member and the second rotating member;
The drive device according to claim 2 , wherein: Each second rotating member has the same shape,
Changing the predetermined angle for each set of the first rotating member and the second rotating member by changing the fixing position of the spring for each second rotating member;
The drive device according to any one of claims 1 to 3, wherein

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