JPH0581854U - Retractor mechanism of developing unit - Google Patents

Abstract

(57) [Summary] [Object] To provide a retracting mechanism for a developing device, which has excellent operability and can securely mount a photosensitive drum. A gap holding means such as an abutting roller for forming a predetermined minute gap between the photosensitive drum 7 and the developing sleeve 9 is provided as a photosensitive member by the weight of the developing device 8 and the elastic force of a biasing spring 14. An upper frame 2 in which the photosensitive drum 7, which is abutted against the drum 7 and is detachable from the developing device 8 and the main body, is opened upward in the upper and lower frames around a pivot axis.
In the electrophotographic printer incorporated in, the retracting means 16 for retracting the developing device 8 in the direction of separating from the photosensitive drum 7 is provided in conjunction with the opening operation of the upper frame body 2.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a retracting mechanism for a developing device in an electrophotographic printer.

[0002]

[Prior Art]

 In an electrophotographic printer, a developing sleeve is provided at the tip of the developing device so as to face the photoconductor drum. By abutting against, a minute gap is formed between the photosensitive drum and the developing sleeve, and the electrostatic latent image on the photosensitive drum is magnetically brush-developed by the rotation of the developing sleeve.

Here, when the abutting roller is abutted against the photosensitive drum, the self-weight of the developing device or the elastic force of a biasing spring (compression spring, tension spring) or a combination thereof is used.

By the way, the photoconductor drum is a consumable item and must be replaced with a new one when it reaches the end of its life due to deterioration over time. Various attachment / detachment mechanisms for the photoconductor drum with respect to the apparatus main body have been proposed, but the apparatus main body is divided into a lower frame and an upper frame, the two are connected by a shaft, and the photosensitive drum and the developing device are arranged. 2. Description of the Related Art An electrophotographic printer of a type in which an upper frame member is rotated upward to open it and a photosensitive drum exposed in an open state is replaced is widely known. In this printer, when a new photoconductor drum is mounted at a predetermined position on the upper frame, the developing device is pushed up against its own weight and spring force.

[0005]

[Problems to be solved by the device]

 However, in the electrophotographic printer, when the size of the device is increased (for example, a form corresponding to 16-inch form), the weight of the developing device also becomes large. Therefore, a large force is required to push the developing device upward, and the photosensitive drum It was a cause of improper installation or had poor operability during installation.

The present invention has been made based on such a background, and has a retracting mechanism for a developing device that solves the above-mentioned drawbacks of the conventional device, has excellent operability, and can securely mount the photosensitive drum. The purpose is to provide.

[0007]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention is provided with a retracting means for retracting the imager in conjunction with the opening operation of the upper frame.

[0008] Specifically, the retracting means is, for example, axially supported by the upper frame body, the developing device pressing piece sandwiching the support shaft, and a bending piece curved inward of a circular locus of the support shaft centering on the pivot shaft. Consists of a retract lever with and.

Further, the lower frame body is provided with an urging protrusion located inside the circular locus of the bending piece and pressed by the spring.

[0010]

[Action]

 With the above structure, when the upper frame is opened, the retracting lever is rotated about the support shaft by the biasing protrusion that relatively slides on the bending piece to press the developing device. The developing device was retracted by one piece.

[0011]

【Example】

 Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of the electronic photo printer according to the embodiment with the upper frame closed, and FIG. 2 is a block diagram of the same with the upper frame open.

In these figures, 1 is a lower frame, 2 is an upper frame, both of which are connected by a pivot 3, and the upper frame 2 is centered on the pivot 3 as shown in FIG. It is designed to rotate clockwise and open upward. The lower frame 1 is provided with a locking projection 4 on one side of the upper part thereof, and by normally engaging the locking claw 5 formed at the lower end of the upper frame 2 with the locking projection 4, the locking projection 4 shown in FIG. As shown, the lower frame 1 and the upper frame 2 are locked.

A photosensitive drum 7 is rotatably attached to a support frame 6 in the upper frame 2, and a developing device 8 is arranged on the right side of the photosensitive drum 7 in the figure. The developing device 8 is provided with a developing sleeve 9 at a position facing the photoconductor drum 7. On both sides of the developing sleeve 9, a well-known abutting roller (not shown) is provided. The abutment roller has a diameter slightly larger than that of the developing sleeve 9, and this abutment roller is abutted against the non-image area of the photoconductor drum 7 by a mechanism described later, so that the gap between the photoconductor drum 7 and the development sleeve 9 is increased. A predetermined minute gap is formed in.

The developing device 8 is provided with guide pins 10 and 11 on the upper and lower sides, and the guide pins 10 and 11 are fitted in the guide grooves 13 of the guide frame 12. The guide groove 13 includes an inclined long groove portion 13a, a set groove portion 13b that restricts the guide pin 10 at the developing setting position, and a retract groove portion 13c that restricts the guide pin 11 at the retracted position. The guide pins 10 and 11 move up and down diagonally along the guide groove 13 to move up and down diagonally to the developing set position (the position shown in FIG. 1) and the retract position (the position shown in FIG. 2). You can move between them.

Although the developing device 8 is at the developing set position shown in FIG. 1 by its own weight, it is further urged toward the photosensitive drum 7 side by an urging spring (in this case, a compression coil spring) 14.

Below the developing device 8 of the upper frame 2, a retractable lever 16 is provided which is swingable about a support shaft 15. The retracting lever 16 has a developing device pressing piece 16a with the support shaft 15 sandwiched therebetween, and a bending piece 16b curved inward of the circular locus of the support shaft 15 centering on the pivot 3. The other end of the tension coil spring 17 whose one end is locked to the lower frame 1 is locked to the tip of the bending piece 16b, whereby the bending piece 16b is biased in the counterclockwise direction and In the frame body 1, it is in contact with a biasing protrusion 18 provided inside the curved piece 16b.

Next, the retracting operation of the developing device 8 when the photosensitive drum 7 is mounted will be described. When the photosensitive drum 7 is replaced, as described above, the upper frame body 2 is opened upward as shown in FIG. 2. In the opening process, the retracting lever 16 is also moved upward. At this time, since the curved piece 16b bites inwardly, the biasing projection 18 biases the curved piece 16b in the clockwise direction while relatively sliding on the curved piece 16.

Then, the retracting lever 16 rotates clockwise around the support shaft 15, so that the developing device pressing piece 16a pushes the developing device 8 obliquely upward. As a result, the imager 8 is guided by the guide frame 12, lifted obliquely upward as indicated by the arrow A in FIG. 2, and held at the retracted position. In this state, since the photoconductor drum 7 and the developing device 8 are completely separated from each other, the photoconductor drum 7 can be easily replaced without receiving an external load from the developing device 8.

After the replacement, when the upper frame 2 is closed, the retracting lever 16 is pulled by the tension coil spring 17 and returns to its original position, and the developing device 8 also receives the action of its own weight and the biasing spring 14. The developing position shown in 1 is restored.

[0020]

[Effect of the device]

 As described above, according to the present invention, since the developing device is retracted in conjunction with the opening operation of the upper frame for replacing the photosensitive drum, the external load of the developing device affects the developing device. Since it is possible to easily mount the photoconductor drum without having to do so, it becomes possible to improve operability and ensure mounting accuracy.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an electrophotographic printer according to an exemplary embodiment of the present invention with an upper frame body closed.

FIG. 2 is a configuration diagram of an electrophotographic printer according to an exemplary embodiment of the present invention with an upper frame body open upward.

[Explanation of symbols]

 1 Lower Frame 2 Upper Frame 3 Axis 7 Photoreceptor Drum 8 Developer 9 Developing Sleeve 12 Guide Frame 14 Energizing Spring 15 Spindle 16 Retracting Lever 16a Developer Pressing Piece 16b Curved Piece 18 Energizing Protrusion

Claims (2)

[Scope of utility model registration request] 1. A gap holding means such as an abutting roller for forming a predetermined minute gap between a photosensitive drum and a developing sleeve is provided on the photosensitive drum by the weight of the developing device, the elastic force of a biasing spring, and the like. While abutting, the photosensitive drum removable from the developing device and the main body, in the upper and lower frame,
In an electrophotographic printer incorporated in an upper frame body that is opened upward about a pivot, a retracting unit that retracts the developing device in a direction away from the photosensitive drum in conjunction with the opening operation of the upper frame body. A retracting mechanism for the developing device, which is provided with. 2. The retracting means is pivotally supported on the upper frame,
The retractor lever is provided with a developing device pressing piece sandwiching the support shaft and a bending piece curved inside the circular locus of the support shaft around the pivot, while the lower frame is provided with the bending piece. Is provided on the inner side of the circular locus of the biasing piece and is pressed by a spring to press the bending piece. 2. The retracting mechanism for the developing device according to claim 1, wherein the lever is rotated about the support shaft so that the developing device is retracted by the pressing member of the developing device.