JPS6347870Y2 - - Google Patents

Description

[Detailed description of the invention] This invention is a developing device that performs development by maintaining a constant distance between a latent image carrier and a cylindrical developer carrier that carries a developer for developing the latent image carrier. Regarding.

In electrophotographic copying machines and the like, fine particles of toner in a developer supplied by a cylindrical developer carrier at a development position are applied to an electrostatic latent image formed on a photoconductor by primary charging and image exposure. Visualization, ie, development, is carried out by adhering. In this case, toner fine particles adhere to the electrostatic latent image on the photoreceptor (latent image carrier) due to the Coulomb force between the two, so the distance between the photoreceptor and the developer carrier, the so-called development gap, is It is necessary to set and maintain the optimum value for development.

Conventionally, when setting the developing gap, appropriate reference holes and reference pins provided on both side plates and the developing section were used, or gap adjustment rings were provided at both ends of the developer carrier and the rings were pushed onto the latent image carrier. Methods such as hitting were used. In addition, in the so-called touch-down development method, as shown in FIG. As the distance between is variable,
The sleeve 1 is slidably supported on a guide member 4 and pulled toward the photoreceptor 3 by a spring 5 to directly press the sleeve 1 against the photoreceptor drum 3, thereby bringing the toner 6 on the sleeve 1 into contact with the latent image. was. but,
In either case, if the parallelism of the rotational axes of the photoreceptor and sleeve itself is not sufficient as it depends on processing and assembly precision, uneven contact between the left and right sides occurs, which causes uneven development and a reduction in copy quality.

The present invention eliminates the above-mentioned drawbacks of conventional developing devices, has a simple structure, allows the latent image carrier and the developer carrier to always maintain good parallelism, and makes the developing gap or pressing force uniform in the width direction. It is an object of the present invention to provide a developing device that can be held in the same manner.

Hereinafter, this invention will be explained in detail based on drawings showing embodiments thereof.

FIG. 2 is a diagram showing an embodiment in which the present invention is applied to the touch-down type developing device previously explained with reference to FIG. 1. Therefore, the same members will be described using the same reference numerals. In the conventional device shown in FIG. 1, the developing device casing 2 was directly attached to the guide member 4 in a slidable manner, and the spring 5 was also directly attached to this. However, in the device of this embodiment, the developing device casing 2 2 is a bearing 8 provided on a base plate 7 that freely slides along the guide member 4, and by supporting a pin 9 provided on the bottom surface of the casing 2, the bearing 8 can freely rotate around this pin 9. It is placed there. Details of this part are shown in FIG. A spring 5 is also attached to the base plate 7.

Since this device is constructed as described above, the sleeve 1 is connected to the base plate 7 by the spring 5.
By being pulled in the direction of the bearing 8, pin 9,
It is pressed against the photosensitive drum 3 via the developing device casing 2 . In this case, since the developing device casing 2 is rotatable around the pin 9, if the sleeve 1 is not completely parallel to the photosensitive drum 3, the resultant force of the tension of the spring 5 and the photosensitive drum 3 The developing device casing 2 rotates around the pin 19 due to the reaction force of the pressing force of the sleeve on the side that is in partial contact with the body drum 3, and the sleeve 1 and the photosensitive drum 3 become parallel. , the contact pressure is automatically adjusted to be equal in all parts in the axial direction.
Therefore, the developer adheres at a uniform density to the electrostatic latent images of the same charge, and uneven development due to poor parallelism is eliminated.

FIG. 4 is a diagram showing an embodiment in which the present invention is applied to a developing device in which an appropriate developing gap is provided between the photosensitive drum and the sleeve. In the figure, a sleeve 11 is pivotally supported by a developing device casing 12 and is provided essentially parallel to the photoreceptor drum 3. At both ends thereof, projecting outward from the cylindrical surface by an amount of a preset optimum developing gap is provided. A gap setting ring 19 is fixed. The developing device casing 12 is rotatable around the pin 19 provided at the bottom thereof by a bearing 18 provided on the top surface of the base plate 17 by supporting a pin 19 similar to the previous embodiment. There is. Both ends of the base plate 17 in the axial direction are bent downward to form a bracket, and an arcuate notch 17a is provided at the lower edge of the bracket. The base plate 17 is supported on the notch 17a with the round bar 14 loosely fitted into the notch disposed parallel to the photosensitive drum 3. Developing device casing 12 and photosensitive drum 3
A leaf spring 15 is provided between the developing device and the machine frame that pivotally supports the developing device, thereby pushing the developing device toward the photosensitive drum 3.

Since this device is constructed as described above, the base plate 17 and the developing device 12 are pushed by the leaf spring 15, and are given the ability to rotate counterclockwise in the figure around the shaft 14. The provided gap setting ring 19 is pressed against the surface of the photoreceptor drum 3, and a developing gap is set between the surface of the sleeve 11 and the surface of the photoreceptor drum 3 therebetween.

In this case, if the sleeve 11 and the photosensitive drum 3 are not parallel, one of the gap setting rings 19 will not come into contact with the photosensitive drum 3, but in this device, the developing device 12 is rotatably attached to the base plate 17 via the pin 19 and bearing 17, so similarly to the previous embodiment, the sleeve 11 automatically becomes parallel to the photosensitive drum 3 and the gap setting rings 19 on both ends come into contact with the photosensitive drum 3 with equal pressure. Therefore, a constant appropriate developing gap is always maintained in the axial direction between the sleeve 11 and the photosensitive drum 3, preventing the occurrence of uneven development.

It is also possible to provide a gap setting ring on the sleeve of the embodiment described in FIGS. 2 and 3, and to apply the mechanism shown in FIG. 4 to a touch-down type developing device.

Furthermore, the present invention can be applied to not only a photosensitive drum but also a belt-like latent image carrier. Note that gravity may be used instead of a spring as a means for pressing the developing device against the photoreceptor drum.

As described above, the present invention prevents the occurrence of uneven development and is effective in improving copy quality.

[Brief explanation of drawings]

FIG. 1 is a side view showing an example of a conventional developing device;
Fig. 2 is a side view showing an embodiment in which the present invention is applied to this device, Fig. 3 is a perspective view showing the developing device casing support mechanism, and Fig. 4 is a side view showing another embodiment of the present invention. be. 1, 11...Developer carrier (sleeve), 2...
...developing device casing (developer carrier shaft supporting material),
3...Latent image carrier (photosensitive drum), 4, 14...
...Guiding member, 5, 15... Spring, 8, 18... Bearing.

Claims (1)

[Scope of utility model registration request] In a developing device that performs development while maintaining a constant distance between a latent image carrier and a cylindrical developer carrier that carries developer for developing the latent image carrier, the developer carrier is moved around its axis. a member rotatably supported by a shaft; a means for varying the distance between the developer carrier and the latent image carrier; and an axis of the developer carrier and the latent image carrier. Means for enabling a developer carrier shaft supporting member to rotate around an axis substantially perpendicular to a plane near the axis of the developer carrier, and biasing the developer carrier in a direction to draw the developer carrier toward the latent image carrier. A developing device characterized by being provided with means.