JPH0432680Y2 - - Google Patents

Description

[Detailed Description of the Invention] Technical Field The present invention includes a developing unit that has a plurality of developing units and is rotatably supported facing a latent image carrier, and each developing unit has a A developer transporting member is provided for transporting the developer in the developer chamber to a development area where the electrostatic latent image on the latent image carrier is visualized.
The present invention relates to a rotary developing device of an image forming apparatus in which each developer conveying member is positioned at a developing position facing a latent image carrier and performs a developing operation by rotation of the developing unit.

BACKGROUND OF THE INVENTION Rotary developing devices of the above type used in image forming apparatuses such as copying machines and printers are well known. In this type of developing device, since it is necessary to rotationally drive the developer conveying member (e.g. a developing roller) brought to the developing position by the rotation of the developing unit, a developing gear is attached to each developer conveying member, and this gear is attached to each developer conveying member. It is rotated by a drive gear. In this case, if each developing gear is driven by a separate drive gear, the structure will not only become complicated but also large in size. Therefore, each developing gear is arranged around the rotation center of the developing unit, A driving gear is fixedly provided in a part other than the developing unit, for example, in the main body of the image forming apparatus, and the developing gear of the developer conveying member brought to the developing position by rotation of the developing unit is engaged with the driving gear. It is advantageous to do so. However, if this configuration is adopted, when the developing gear revolving around the rotation center of the developing unit starts to engage with the drive gear, there is a possibility that the tips of the teeth of both gears will abut each other. If this is left unattended and the developing gear is allowed to revolve, the teeth of the gear will be damaged or the developing gear will stop rotating, making it impossible to properly mesh the two gears.

OBJECT It is an object of the present invention to eliminate the above-mentioned drawbacks and to provide a developing device of the type described at the outset, in which it is possible to easily and correctly mesh each developing roller gear with the drive gear.

Configuration In order to achieve the above object, the present invention has a developing gear that drives each developer conveying member, which is arranged around the center of rotation of the developing unit so as to be rotatable with respect to the unit. A driving gear with which the developing gear selectively meshes is supported immovably in a portion other than the developing unit, and each developing gear revolves around the rotation center of the developing unit as the developing unit rotates, thereby driving the developing gear. It is configured to mesh with a gear, and when the driving gear rotates during a developing operation and transmits rotational force to the developing gear, the flanks of both gears that are not in contact with each other to transmit force are removed. , the teeth of both gears are formed so that when the developing gear starts to engage with the driving gear due to revolution of the developing gear, the teeth of both gears can come into line contact with each other.

Embodiments of the present invention will be described below with reference to the drawings. In order to understand the present invention, the overall structure and operation of the illustrated developing device will first be explained.

In FIG. 1, reference numeral 1 indicates a developing unit of a rotary developing device supported by a main body 2 of the copying machine. A plurality of developing units 3, 3R, and 3B are integrated into the developing unit 1, and the developer chambers 4, 4R, and 4B of each of the developing units 3, 3R, and 3B are made of aluminum or the like. It is divided by three partition walls 6, 6R, 6B of the casing member 5 made of a non-magnetic material and two end walls 7, 8 (see Figs. 3 and 4) fixed to both ends thereof. . Each developer chamber 4,
Developers 9, 9 of different colors are in 4R and 4B.
In this example, it is assumed that these developers are black, red, and blue, respectively. It is also possible to form a full-color image by storing cyan, yellow, and magenta toner developers in each developer chamber, or to form a full-color image by storing cyan, yellow, and magenta toner developers in each developer chamber. It can also be configured to use selectively. Although it is also possible to use a one-component developer that does not contain a carrier as the developer, the example shown in the figure is a two-component developer that contains a carrier and toner, and a magnetic developer, at least a part of which is a magnetic material. is used. Each of the first to third developing units 3, 3R,
Although the developing units 3B are arranged radially around the rotation center O of the developing unit 1, all of them have the same structure. Container 3R, 3
Regarding each part of B, R and B are added to the reference numerals given to each element of the first developing device 3, and a redundant explanation thereof will be omitted.

As will be described later, the developing unit 1 is rotatably supported around its rotation center O, and each developing device (more precisely, its developing roller) rotates to a predetermined developing position to perform a developing operation. FIG. 1 shows a state in which the first developing device 3 occupies the developing position.

In FIG. 1, a developer conveying member provided in the first developing device 3, in the example shown, the developing roller 10 is partially exposed through the opening formed by the two partition walls 6, 6R (also in FIG. ), this developing roller 10
occupies a predetermined developing position with respect to the latent image carrier rotatably supported by the copying machine main body 2, in this example the photoconductor drum 11 (even if a latent image carrier consisting of a photoconductor belt is used) (As is well known, depending on the type of image forming apparatus, a latent image carrier consisting of a dielectric belt or a dielectric drum is used.) At this time, the developing roller 10 is positioned parallel to the photosensitive drum 11 with a predetermined minute gap therebetween. As can be seen from FIG.
8, each of which is rotatably supported by the copying machine main body 2.
One support shaft 13 on the back side (left side in FIG. 2) passes through the end wall 8, and a developing roller gear 14 is fixed to the tip thereof.

Inside the developer chamber 4, an impeller 16 having a large number of blades 15 is disposed.
It is rotated counterclockwise in the figure. As a result, the developer in the developer chamber 4, that is, the toner and the carrier, is supplied to the developing roller 10 while being agitated, and the toner is frictionally charged to a predetermined polarity by the agitation of the toner and the carrier.

Inside the developing roller 10, a magnet 21 having magnetic poles consisting of an S pole and an N pole is fixedly arranged on the casing member 5 of the developing unit 1, as indicated by S and N in FIG. As a result, the developing roller 10 passes through the aforementioned developing roller gear 14 to the first
When the developing roller 10 is rotated counterclockwise in the figure, the magnetic developer 9 supplied to the developing roller 10 is supported on the surface of the developing roller 10 by the magnetic force of the magnet 21 and is conveyed counterclockwise. The developer being conveyed is subjected to a scraping action by a doctor blade 22 fixed to the casing member 5, and a predetermined amount of the developer that has passed through the blade 22 is sent toward the photoreceptor drum 11 with the layer thickness regulated. It will be done.

On the other hand, the photosensitive drum 11 is rotationally driven in the clockwise direction in FIG. It is formed in a manner known per se. When this latent image reaches the opposing development area D between the photoreceptor drum 11 and the developing roller 10, the charged toner in the developer also conveyed to this area D electrostatically transfers to the electrostatic latent image, and the latent image is visualized. This visible image is transferred to a transfer paper (not shown) by a transfer device (also not shown), and the transferred visible image is fixed by a fixing device (not shown). The developer that has passed through the development area D is returned to the inside of the developer chamber 4, mixed with other developers in this chamber, and used again.

As shown in FIGS. 2 to 4, the developing unit 1
A positioning pin 78 is protruded from the end wall 8 on the back side of the unit 1 and is rotatably supported on the side plate 79 on the back side of the copying machine body via a bearing 81. 1 front end wall 7
is rotatably supported by the support arm 70 of the unit carrier 62, whereby the entire unit 1 is positioned at a predetermined position within the main body of the copying machine and is rotatably supported. The unit carrier 62 is
By pulling it out toward the front as shown in the figure, the developing unit can be taken out of the copying machine main body while being supported by the carrier 62.

When forming a visible image with the red or blue developer contained in the second or third developing device 3R, 3B,
The developing unit 1 set at a predetermined position within the main body of the copying machine is rotated clockwise in FIG.
Developing roller 10 of the second or third developing device 3R, 3B
R or 10B is brought to the developing position where the developing roller 10 of the first developing device 3 shown in FIG. 1 is located, and a developing operation is performed. In order to rotate the developing unit 1 set in the main body of the copying machine, a unit carrier 6 is mounted as shown clearly in FIG. 4 and schematically shown in FIG.
A gear 8 supported on the unit carrier 62 is driven by a drive motor 88 supported on the unit carrier 62.
9 meshes with a unit gear 90 formed on the circumferential surface of the rear end wall 8 of the developing unit 1. When the operator selects and presses a color conversion key switch (not shown) with the developing unit 1 pushed into the copying machine main body 2 and set, the drive motor 88 is activated and the intervening gear 89 is inserted between the motor 88 and the gear 89. The clutch is turned on, and the developing unit 1 rotates around its rotation center O in the clockwise direction in FIGS. 1 and 5. As a result, the developing roller 10 of the selected developer, for example, the first developer 3 as shown in FIGS. 1 and 5, reaches the developing position, at which point the motor 88 stops operating or the clutch is turned off, the developing unit 1 is stopped, and the developing operation described above is performed.

The developing roller brought to the developing position, for example the developing roller 10 shown in FIGS. 1 and 5, rotates counterclockwise as described above, and this drive is performed as shown in FIGS. 2 and 5. The drive gear 11 is rotatably supported on the support shaft 110 of the photoreceptor drum 11.
1 rotation is brought to the developing position of the developing roller 1
This is done by being transmitted to gear 14 of 0.
The developing unit 1 is rotated by the drive motor 88 to rotate the developing rollers 10R and 1 of the other developing units 3R and 3B.
When 0B is brought to the developing position, these developing roller gears 14R and 14B are similarly connected to the drive gear 1.
11 and is rotationally driven.

As shown in FIG. 5, each developing roller gear 14, 1
The centers of 4R and 14B are arranged at equal intervals around the center of rotation O of the developing unit 1, and at equal distances from the center. Further, the rotation center O' of the development roller gear 14 (the same applies to other development roller gears) located at the development position, the rotation center O of the development unit 1, and the rotation center O'' of the drive gear 111, which is stationary, are on the same straight line l. The developing rollers 14, 14 are located above, or approximately on this straight line l, and thus each developing roller 14, 14 is rotated about the center O of the developing unit 1.
When R and 14B revolve around this center O, these gears do not interfere with the drive gear 111 and can mesh in a predetermined state. Further, the drive gear 111 may be supported by any suitable part other than the developing unit 1, and may be supported by a part of the main body of the copying machine other than the support shaft of the photosensitive drum 11 or by the carrier unit 62.

By the way, if the driving gear 111 is disposed in an immovable position as described above and the developing roller gear is configured to revolve and selectively mesh with the driving gear 111, as the developing unit 1 rotates, one of the developing roller gears 14 , 14R or 14B starts to engage with the drive gear 111, but at this time, the developing roller gear 14, 14R or 14B and the drive gear 111
If the teeth of the gear have a normal shape, the tips of the teeth of both gears will collide with each other, as shown in Figure 7, and there is a risk that these gears will stop or the teeth of the gears will be damaged. be. Therefore, in order to eliminate this inconvenience, the present invention is constructed as follows.

That is, the developing unit 1 rotates around its center O in the clockwise direction (direction of arrow Q) in FIG. When the drive gear 111 rotates in the clockwise direction indicated by R during the developing operation to transmit rotational force to the developing gear, the flanks of both gears that are not in contact with each other in order to transmit force. is cut away from the normal tooth profile shown by the chain line in FIG. 6 as shown by the solid line. That is, the tooth profile of the drive gear 111 and the developing roller gears 14, 14R, and 14B that engage with the drive gear 111 is different from that of a normal gear, and the portion shown by the chain line in FIG. 6 is removed from the normal tooth shape. It forms into a form. By doing this, when the developing roller gears 14, 14R, and 14B engage with the drive gear 111 while revolving around the center O of the developing unit 1 in the direction of the arrow Q, even if the tips of the teeth of both gears touch each other, Since the linear tips 118 of these are in line contact with each other, the abutment between the tips of the teeth is immediately released,
As the revolution of the developing roller gear progresses, the two become in a normal meshing state. After properly meshing, the drive gear 111 rotates clockwise (arrow R),
When transmitting force to the developing roller gear, the flanks where the two contact each other have the same tooth profile as a normal tooth, so the driving force of the drive gear 111 can be transmitted to the developing roller gear without any problem, without impairing its function as a gear. .

Note that when the developing roller gear engages with the drive gear 111 while revolving, if at least one of both gears starts rotating immediately before the engagement, the abutment between the tips of the teeth can be made more reliably and quickly. This is advantageous because it can be released immediately. To rotate the developing roller gear as described above, it may be rotated by an appropriate driving means other than the driving gear. Further, in this case, it is desirable to set the rotation direction of the developing unit 1 in a direction in which the relative speed in the engagement area of both gears increases. For example, in the examples shown in FIGS. 5 and 6, if the driving gear 111 is rotated in the direction of arrow R just before the developing roller gear engages with the driving gear 111 due to its revolution, the rotating direction of the developing unit 1 is turned clockwise (direction of arrow Q) as shown in FIG. In this way, when the developing roller gear revolves and engages with the drive gear 111, the relative speed of the engagement area between both gears increases, and the teeth of both gears can be immediately brought into a normal meshing state. . Furthermore, since the rotation direction of the drive gear 111 described above, that is, the clockwise direction R, corresponds to the rotation direction of the drive gear 111 during normal developing operation, the gear 111 can be rotated without any problem until just before it meshes with the development roller gear. I can do it. Further, when the developing roller gear is rotated (rotated) immediately before the developing roller gear engages with the driving roller gear 111 while the driving gear 111 is stopped, the revolution direction of the developing roller gear is clockwise Q in this example. Therefore, the rotation direction of the roller gear is also
The clockwise direction may be used so that the relative speed with respect to the drive gear 111 increases.

The present invention is not limited to a developing device in which each developing device is integrally constituted by one casing member as in the illustrated developing device, and the entire developing device constitutes a developing unit. It goes without saying that the present invention can be applied to a developing device that has separate casing members and is assembled to a unit rotating body to form a developing unit. can be similarly applied.

The present invention can also be applied when the developer conveyance member consists of a developer conveyance belt, or a magnet roller rotatably installed inside a belt or roller. In these cases, the developer conveyance belt The gear attached to the magnetic roller or the gear attached to the magnet roller becomes a developing gear (corresponding to the developing roller gear of the embodiment).

Effects According to the present invention, by only slightly changing the tooth profile of the driving gear and the developing gear from that of a normal gear, the collision between the tips of the teeth of both gears can be eliminated or the collision can be immediately released. This allows both gears to mesh smoothly and correctly.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view of the developing device when the developing unit is set in the copying machine main body, FIG. 2 is a cross-sectional view taken along the line -- in FIG. FIG. 4 is a perspective view showing the developing unit removed from the storage stand; FIG. 4 is a perspective view of the storage stand and related elements viewed from the back side with the developing unit removed; FIG. FIG. 6 is an explanatory diagram illustrating the rotational operation of the developing unit. FIG. 6 is an explanatory diagram illustrating the tooth profile of the gear according to the present invention and its function. FIG. It is an explanatory diagram explaining a malfunction that occurs. 1... Developing unit, 3, 3R, 3B... Developing device, 111... Drive gear, O... Center of rotation.

Claims (1)

[Scope of Claim for Utility Model Registration] A developing unit having a plurality of developing devices and rotatably supported facing a latent image carrier,
Each developing unit is provided with a developer conveying member that conveys the developer in the developer chamber to a developing area where the electrostatic latent image on the latent image carrier is visualized. In a rotary developing device of an image forming apparatus in which each developer conveying member is positioned at a developing position facing a latent image carrier to perform a developing operation, a developing gear that drives each developer conveying member is a part of the developing unit. A drive gear is rotatably disposed around the center of rotation relative to the unit and selectively meshes with the developing gear as the developing unit rotates, and is immovably supported at a portion other than the developing unit;
As the developing unit rotates, each developing gear revolves around the rotation center of the developing unit, and the developing gear is configured to mesh with a driving gear, and the driving gear rotates during a developing operation to transmit rotational force to the developing gear. When the teeth of both gears are formed by cutting off the flanks of both gears that are not in contact with each other to transmit force, and when the developing gear starts to engage with the driving gear as the developing gear revolves, The developing device is characterized in that the teeth of both gears are configured so as to be in line contact with each other.