JP4203790B2 - Developing device for electrophotographic printing machine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a developing device for an electrophotographic printing machine, and more particularly to a developing device having a developing roller and a squeeze roller that can be brought into and out of contact with a photosensitive drum.
[0002]
[Prior art]
A conventional developing apparatus of this type is disclosed in Japanese Patent Application Laid-Open No. 11-288173. In this conventional developing device, each of the developing roller mounting plate for supporting the developing roller and the squeeze roller mounting plate for supporting the squeeze roller is rotatably supported on separate spindles or on the same spindle. Each roller is biased toward the photosensitive drum in the contact direction by an individual spring or a common spring. Each mounting plate is connected to an eccentric cam shaft via an arm. By rotating each eccentric cam shaft, each mounting plate is separated from the photosensitive drum via each arm. It is designed to rotate.
[0003]
[Problems to be solved by the invention]
In the above conventional configuration, each roller is biased to the photosensitive drum by a spring, so that the roller contact pressure on the photosensitive drum surface can be finely adjusted and the contact pressure can be managed according to the application state of the liquid toner. It was difficult. Further, as described above, since the mechanisms for contacting and separating each roller from the surface of the photosensitive drum are separate, these configurations become complicated, the number of parts increases, and the space is also disadvantageous.
[0004]
The present invention has been made in view of the above, and it is possible to easily adjust the contact pressure of the developing roller and the squeeze roller to the photosensitive drum individually, and to make the respective rollers contact and separate from the photosensitive drum. Provided with a developing device in which each contact mechanism can be made simple in a small space by using only one mechanism, and the rotation drive mechanism of each roller can be made compact. It is intended to do.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, a developing device in an electrophotographic printing machine according to the present invention is a developing device of an electrophotographic printing machine in which a developing roller and a squeeze roller are arranged so as to be able to contact and separate from a photosensitive drum. The developing box that supports the developing roller and the squeeze box that supports the squeeze roller are rotatably supported on the same support shaft, and an air cylinder that individually rotates these is connected to the developing box and the squeeze box. Each air cylinder is connected to an air pressure source via a pressure reducing valve, and by adjusting the pressure reducing valve, the contact pressure of each roller to the photosensitive drum can be arbitrarily and finely adjusted. It has become.
[0006]
In the developing device of the electrophotographic printing machine,
The support shaft that supports the developing box and the squeeze box is a rotation support shaft that is connected to the rotation drive device, and is connected to the development roller via a developing roller drive mechanism at one side of the rotation support shaft in the axial direction. The squeeze roller driving mechanism connected to the squeeze roller.
[0007]
[Operation]
By individually expanding and contracting the air cylinder, the developing roller box and the squeeze roller box are individually rotated, and the squeeze roller is brought into contact with and separated from the photosensitive drum. The contact pressure of each roller to the photosensitive drum at this time is adjusted by controlling the air pressure supplied to each air cylinder.
[0008]
Further, the developing roller and the squeeze roller are rotationally driven through the respective driving mechanisms by the rotation support shafts that rotatably support the developing roller box and the squeeze roller box.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the drawings.
[0010]
In FIG. 1, reference numeral 1 denotes an example of a developing device according to the present invention attached to an electrophotographic printing machine using liquid toner. The developing device 1 is configured so that the developing roller 2 and the squeeze roller 3 can contact and separate from the photosensitive drum 4. It is installed. The developing roller 2 and the squeeze roller 3 are respectively supported in a developing box 5 and a squeeze box 6 that are opened on the photosensitive drum 4 side, and the boxes 5 and 6 are rotated in parallel with the photosensitive drum 4 therebetween. The support shaft 7 is rotatably supported via a bearing. The developing roller 2 is in contact with a toner squeezing roller 2 a supported in the developing box 5.
[0011]
Arms 5a and 6a project from the lower portions of the boxes 5 and 6, and the other ends of the air cylinders 9 and 10 that are rotatably supported by the body 8 on one end are pivoted on the arms 5a and 6b. By freely connecting and expanding and contracting the air cylinders 9 and 10, the boxes 5 and 6 are rotated about the support shaft 7, whereby the rollers 2 and 3 are brought into contact with the surface of the photosensitive drum 4. It comes to come in contact with and away from.
[0012]
Each air cylinder 9 and 10 is connected to an air pressure source via a known electromagnetic switching valve and pressure reducing valve (not shown), and the contact pressure of each roller 2 and 3 to the photosensitive drum 4 adjusts the pressure reducing valve. By doing so, it can be adjusted arbitrarily and finely.
[0013]
The rotary support shaft 7 is rotatably supported by brackets 11a and 11b fixed to the machine frame 8, and a rotary drive device (not shown) is connected to one end of the rotary support shaft 7 through a universal joint 7a. The rotation spindle 7 is rotated in synchronization with the photosensitive drum 4. The rotation support shaft 7 is connected to the developing roller 2 and the toner squeezing roller 2a via the developing roller driving mechanism 12, and to the squeeze roller 3 via the squeeze roller driving mechanism 13. The two drive mechanisms 12 and 13 are distributed to the outside of the boxes 5 and 6 and to both sides in the axial direction of the support shaft 7, that is, the developing roller drive mechanism 12 is driven to the base end side of the support shaft 7 and squeeze roller driven. The mechanism 13 is disposed on the distal end side of the support shaft 7.
[0014]
The developing roller driving mechanism 12 includes a driving gear 14 fixed to the rotation support shaft 7, an intermediate gear 15 meshing with the driving gear 14, a developing roller 2 meshing with the intermediate gear 15, and a toner squeezing roller 2a. The driven gears 16a and 16b are fixed to each other, and the driven gears 16a and 16b are rotated through the intermediate gear 15 by the rotation of the rotary support shaft 7, so that the developing roller 2 is opposed to the photosensitive drum 4 The toner squeeze roller 2a rotates in the same circumferential direction and at a higher circumferential speed than the photosensitive drum 4, and the toner squeezing roller 2a rotates in the opposite direction to the developing roller 2 in the opposite direction.
[0015]
The squeeze roller drive mechanism 13 includes a drive gear 17 fixed to the rotary support shaft 7, a first intermediate gear 18a meshing with the drive gear 17, and a second intermediate gear 18b coaxially integrated with the first intermediate gear 18a. The third intermediate gear 19a meshed with the second intermediate gear 18b, the fourth intermediate gear 19b coaxially integrated with the third intermediate gear 19a, and the squeeze roller 3 meshed with the fourth intermediate gear 19b The squeeze roller 3 includes a driven gear 20, and the rotation of the rotation support shaft 7 causes the squeeze roller 3 to face the photosensitive drum 4 via the intermediate gears 18 a, 18 b, 19 a, 19 b, and in the opposite direction to the excess toner. It rotates at a peripheral speed suitable for scraping. Each intermediate gear described above is supported by each box.
[0016]
In the above configuration, the developing box 5 and the squeeze box 6 are rotated about the rotation support shaft 7 by extending and contracting the air cylinders 9 and 10 connected to the developing box 5 and the squeeze box 6 respectively. As a result, the developing roller 2 and the squeeze roller 3 housed therein are individually brought into contact with and separated from the surface of the photosensitive drum 4. At this time, the contact pressure of the rollers 2 and 3 on the photosensitive drum 4 side is adjusted by adjusting the air pressure supplied to the air cylinders 9 and 10 with a pressure reducing valve.
[0017]
Further, when the rotation support shaft 7 is rotated, the developing roller 2 and the toner squeezing roller 2 a are exposed via the developing roller driving mechanism 12, and the squeeze roller 3 is exposed via the squeeze roller driving mechanism 13. It is rotated in synchronization with the drum 4.
[0018]
【The invention's effect】
According to the present invention, the contact pressure of the developing roller and the squeeze roller that are in contact with and away from the photosensitive drum to the photosensitive drum can be easily performed individually by adjusting the air pressure to the air cylinder.
[0019]
Further, since each roller can be driven by one air cylinder so that the contact pressure can be adjusted as described above, this contact / separation mechanism can be simplified in a small space.
[0020]
Further, the developing roller driving mechanism and the squeeze roller driving mechanism for driving each roller are provided on both sides in the axial direction of the rotation support shaft that rotatably supports the developing roller box and the squeeze roller box, thereby driving both the rollers. The mechanism can be integrated compactly without interfering with each other.
[Brief description of the drawings]
FIG. 1 is a partially broken sectional view showing an air cylinder that rotates a developing roller box of a developing device according to an embodiment of the present invention.
FIG. 2 is a partially broken sectional view showing an air cylinder that rotates a squeeze roller box of the developing device according to the embodiment of the present invention.
FIG. 3 is a bottom view showing an air cylinder that rotates a squeeze roller box;
FIG. 4 is a plan view showing a developing device according to an embodiment of the present invention.
FIG. 5 is a side view of the developing device shown in FIG. 4 as viewed from the left side.
6 is a side view of the developing device shown in FIG. 4 as viewed from the right side.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Developing device, 2 ... Developing roller, 2a ... Toner squeeze roller, 3 ... Squeeze roller, 4 ... Photosensitive drum, 5 ... Developing roller box, 5a, 6a ... Arm, 6 ... Squeeze roller box, 7 ... Rotating spindle, 7a ... Universal joint, 8 ... Airframe, 9, 10 ... Air cylinder, 11a, 11b ... Bracket, 12 ... Developing roller drive mechanism, 13 ... Squeeze roller drive mechanism, 14, 17 ... Drive gear, 15, 18a, 18b, 19a 19b, intermediate gears, 16a, 16b, 20 ... driven gears.

Claims (2)

In the developing device of the electrophotographic printing machine in which the developing roller and the squeeze roller are arranged so as to be able to contact and separate from the photosensitive drum,
The developing box that supports the developing roller and the squeeze box that supports the squeeze roller are rotatably supported on the same support shaft, and an air cylinder that individually rotates these is connected to the developing box and the squeeze box. And
Each air cylinder is connected to an air pressure source via a pressure reducing valve,
A developing device for an electrophotographic printing machine , wherein the contact pressure of each roller to the photosensitive drum can be arbitrarily and finely adjusted by adjusting the pressure reducing valve . In the developing device of the electrophotographic printing machine according to claim 1,
The support shaft that supports the development box and the squeeze box is a rotation support shaft that is connected to the rotation drive device.
An electrophotographic printer characterized in that it is connected to a developing roller via a developing roller drive mechanism at one side in the axial direction of the rotating support shaft and connected to a squeeze roller via a squeeze roller driving mechanism at the other part in the axial direction. Development device.

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