JP2573232B2 - Developing device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a developing device that develops, for example, an electrostatic latent image formed on a recording medium.

<Prior Art> Copiers and the like include a developing device that attaches a toner made of a color pigment to the electrostatic latent image in order to visualize the electrostatic latent image formed on a recording medium or the like. Have been. Here, a plurality of developing devices each containing toner of each color for colorizing the electrostatic latent image as well as black are provided in the copying machine, and these developing devices are selectively used. For example, when forming a full color, cyan,
Magenta and yellow are further provided with respective developing devices containing black toner as necessary.Electrostatic latent images on the recording medium, which have been color-separated through filters of the respective colors, are developed with the toners of the respective colors, and are formed on copy paper. A full-color copy image is obtained by superimposing toners of each color.

When the developing device is not used for development, it is necessary to control the toner so that the toner does not adhere to the latent image. For this purpose, for example, the developing gap (the distance between the recording medium and the developing unit of the developing device) is switched, and the toner is recorded. Consideration is given so that the medium is not contacted or transported to the developing area facing the medium.

<Problems to be Solved by the Invention> In the case where the developing device is not used for development as described above, if the developing gap and the like are switched, the developing conditions vary, and the image density changes. Particularly, unless the development gap is accurately positioned, a normal image cannot be always formed.

When a magnetic brush developing method is used as a developing device, there is a device in which a position of a magnet constituting a developing unit is shifted so as to prevent a developing brush from contacting a recording medium. If not, not only does the image density change, but also a carrier (when a two-component developer is used) adheres to the recording medium, and the image quality is significantly reduced.

Therefore, Japanese Utility Model Application Laid-Open No. 58-11766 provides a developer transporting unit having the same configuration as the developing unit that receives the developer removed from the developing unit and supplies the developer to the developing unit again. It is proposed to provide a shutter that regulates the supply of the developer to the developing unit between the developing device and the developing device. The developing device has a configuration that shuts off the supply of the developer to the developing unit when the developing device is not in the development. .

However, in this method, the conveying unit also serves as the stirring unit, and the developer removed from the developing unit is supplied to the developing unit as it is by the conveying unit, so that the developer is not sufficiently stirred, The developer removed from the developing section is supplied as it is. Further, since the shutter is provided separately between the conveying means and the developing unit, a position where the shutter is provided is required, and the entire developing device becomes large.

Japanese Utility Model Laid-Open Publication No. 52-25743 proposes a device in which a movable shutter is provided between a developing unit and a stirring unit, and the supply state of the developer to the developing unit is shut off by the shutter. I have. However, this device also requires a separate shutter, which is the same as that described above. In addition, the shutter configuration does not reliably shut off the developing unit collected from the developing unit, and a part of the developer may remain in the developing unit.

An object of the present invention is to control the supply of a developer to a developing unit constituting a magnetic brush and to switch between a developing state and a non-developing state, for example, in a developing device employing a magnetic brush developing method.

<Means for Solving the Problems> The developing device of the present invention includes a supply path for supplying a developer to a developing section for performing development, and a recovery path for collecting the developer after development from the developing section. And a partition part that divides the recovery path and the supply path so as to guide the developer from the recovery path to the supply path, and forms a developer circulation path with the supply path divided by the partition part. A stirrer rotatably provided to stir the supplied developer is disposed, and a shutter that covers an outer periphery of the stirrer and opens and closes the supply path is provided. The shutter has an inlet that communicates with the stirrer. And a closing part for closing an outlet communicating with the developing part, and a slit part for opening, so that the inlet / outlet rotates to a position for simultaneously opening and closing the supply path with respect to the supply path, and Rotatably installed coaxially with the shaft It is characterized in.

<Function> In the developing device of the present invention, by appropriately rotating the shutter having the slit, the passage for supplying the developer is closed or opened. Accordingly, when the supply path is opened by the shutter, the developer is supplied to the developing section while being sufficiently stirred by passing through the stirring means, and is subjected to development.

When the shutter is closed, the outlet from the stirring means to the developing unit is closed, and there is no developer supplied to the developing unit. The time to be completely recovered via the service is shortened. Therefore, it is possible to quickly prevent the toner from the developing device from adhering to the surface of the recording medium.

Further, since the shutter is provided so as to be rotatable coaxially with the rotation axis of the stirring means, a special space for providing the shutter is not required.

<Embodiment> FIG. 1 is a sectional view showing a specific example of the developing device of the present invention. In the figure, reference numeral 1 denotes a developing tank which forms an exterior housing the developer, and 2 denotes a developing roller for carrying the developer to a photosensitive member 3 which is a recording medium by magnetic force and bringing the developer into contact with the photosensitive member 3 for development.
The developing roller 2 has a structure in which a magnet 22 whose periphery is magnetized to each pole is provided in a cylindrical non-magnetic sleeve 21 made of aluminum or the like, and the S pole (main pole) of the magnet 22 is a photoconductor. 3 is fixed. The sleeve 21 is in the developing tank 1
, And is rotatably supported with respect to. Therefore, when the sleeve 21 rotates, the developer is magnetically attracted to the surface of the sleeve 21 and is conveyed to the photoconductor 3. At this time, the developer is formed in a brush shape along the magnetic force of the main pole of the magnet 22 at a position facing the photoconductor 3, and the photoconductor 3 is rubbed in this state.

In order to collect the developer after the development, the developer is pumped up in the upper portion of the developing roller 2 and circulated to a position for further stirring the developer. Is provided with a conveying roller 4. The transport roller 4 has the same configuration as the developing roller 2 and rotates the sleeve to magnetically attract the developer to the surface of the sleeve and transports the developer. The developer transported on the transporting roller 4, particularly on the sleeve, is scraped off from the surface of the sleeve by the scraper 5 with the tip in contact with substantially the top of the sleeve.

The scraper 5 is disposed in an inclined state, and the other end is extended to a stirring section for stirring the developer. Above the scraper 5, a toner stirring roller 6 for mixing and stirring the supplied toner and developer is rotatably provided. Although not shown, the toner is contained in the toner hopper provided above the developing tank 1,
The developer is supplied to the vicinity of the toner stirring roller 6 in the developing tank 1 according to a command from the toner concentration control means of the developer. The developer mixed and stirred with the toner via the toner stirring roller 6 reaches the stirring section along the scraper 5.

The stirring section includes a rotatable stirring roller 7 and a shutter 8 having a slit 9 formed in a cylindrical part provided on the outer periphery of the stirring roller 7. As shown in the figure, the stirring roller 7 is disposed in the middle of a supply passage for supplying the collected developer after development to the developing roller 2 via the transport roller 2 provided in the collection path. A shutter 8 is arranged on the outer periphery of the stirring roller 7 to control the supply or non-supply of the developer through this passage. The rotation of the shutter 8 is controlled separately from the rotation of the stirring roller 7. The details will be described later.

A passage for supplying the developer to the developing roller 2 is formed by a partition member 10 and a portion 11 in which a part of the developing tank 1 is curved. The partitioning member 10 also separates between the transport roller 4 and the stirring roller 7, and the developer is directly
The inside of the developing tank 1 is partitioned so as not to flow into the developer tank 1 to form a circulation path of the developer. Here, when the slit 9 is rotated to the position shown in the figure, the shutter 8 opens the supply path of the developer to the developing roller 2 and supplies the developer to the developing roller 2 via the stirring roller 7. Making it possible. When the shutter 8 rotates about 90 °, the cylindrical portion (non-slit portion) that constitutes a closed portion other than the slit is a partition member.
The inlet 12 and outlet 13 of the passage formed by the curved portion 11 of the developing tank 1 are closed. Thus, the supply of the developing roller 2 developer is stopped.

FIG. 2 is a sectional view showing details of a stirring roller 7 and a shutter 8 for stirring the developer, and FIG. 3 is a side view showing details of a driving unit for controlling the rotation drive of the shutter 8.

In the figure, the stirring roller 7 has one of its shafts 71 rotatably held in the developing tank 1. The shutter 8 is rotatably provided with respect to a shaft 71 of the stirring roller 7, and for this purpose, the shutter 8 is supported on the shaft 71 via a bearing 14 such as a ball bearing. One end of the shutter 8 is rotatably held in the developing tank 1.
The protruding end is connected to the shaft 71 of the stirring roller 7 via the spring clutch 15. A drive gear 16 to which a rotational force is transmitted is fixed to an end of the shaft 71 opposite to the spring clutch 15, and rotates the stirring roller in a fixed direction.

The spring clutch 15 has a boss 72 fixed to the shaft 71.
A spring 151 is wound between the shaft 151 and the shaft portion 81 of the shutter 8, and one end of the spring 151 is fixed to a clutch cover 152 disposed on the outer periphery of the spring 151. Spring 151 is hose part 7
It is wound in the direction to tighten 2 but clutch cover 152
Is braked (rotation-restricted state), the state is separated from the boss portion 72, that is, the state becomes loose, and the rotational force of the shaft 71 is not transmitted to the shutter 8.

As shown in FIG. 3, the clutch cover 152 of the spring clutch 15 has four stop claws 153 arranged at 90 ° intervals on its outer periphery and two 180 ° for position detection (rotational position of the shutter 8). Projections 154 arranged at intervals are integrally formed. One end of an arm 18 rotatably provided on a shaft 17 attached to the developing tank 1 is positioned corresponding to the stop claw 153. arm
The other end of the arm 18 is urged by the urging force of the spring 19
18 is always rotated counterclockwise in the figure. for that reason,
The tip of the arm 18 is in contact with the clutch cover 152. An operating piece 201 of a solenoid 20 is connected to the arm 18 to rotate the arm 18 clockwise against the urging force of the spring 19. The spring 19 is interposed between the arm and the solenoid 20. Also, protrusion 15
4, a position detection switch 202 is attached to the developing tank 1 together with the solenoid 20, and if the protrusion 154 presses the operating portion of the detection switch 202 as shown in the figure, the slit 9 of the shutter 8 is Is in an open state (the state shown in FIG. 1).

In the developing device having the above-described configuration, when performing development, it is necessary to open a passage for supplying the developer to the developing roller 2. Therefore, the rotation of the developing roller 2 (sleeve
The various rollers are also rotated in the direction of the arrow in accordance with (21 rotation). Then, the rotational force of the shaft 71 is transmitted to the shutter 8 via the spring clutch 15 in accordance with the rotation of the stirring roller 7. That is, the solenoid 20 is energized and the arm 18
Is rotated clockwise (p direction). As a result, the engagement between the tip of the arm 18 and the stop claw 153 is released, and the spring 151 is tightened to the boss 72 of the shaft 71 in accordance with the rotation of the shaft 71, and the shutter 8 rotates.

The solenoid 20 has one arm 18 and a stop claw 153.
, And the current is released to engage the next stop claw 153. Accordingly, the spring 151 is loosened by the engagement operation between the tip of the arm 18 and the next stop claw 153, and the rotation of the shutter 8 is stopped. Therefore, the rotation of the shutter 8 is controlled so as to rotate 90 degrees and stop. Shutter 8
Is rotated 90 ° and stops, the slit 9 of the shutter 8
Are opposed to the inlet 12 and the outlet 13 of the developer passage as shown in FIG. 1 to open the passage. Therefore, the developer is supplied to the developing roller 2 while being stirred by the rotation of the stirring roller 7, and is used for development. In this case, while the developer is being supplied to the developing roller 2, the detection unit of the sensor 25 that detects the toner concentration is located in the developing tank 1, so that the toner concentration is detected. In response to this detection output, the supply of toner into the developing tank 1 is controlled. In addition, since the protrusion 154 of the clutch cover 152 presses the operating portion of the detection switch 202 provided correspondingly, the detection switch 202 detects that the shutter 8 opens the passage and is in the developing state. To the control unit.

The developer is supplied to the developing roller 2 as described above,
After the development, the above-described circulation path formed in the developing tank 1 which is fed to the transport roller 4 according to the rotation of the roller 2 and further transported by the transport roller 4 to reach the stirring roller 7 again along the scraper 6. Is circulated along.
Thereafter, when the development of the photoconductor 3 is completed and the development by the developing device becomes unnecessary, a control for stopping the supply of the developer is executed. For this reason, the solenoid 20 is energized, and after disengagement of the tip of the arm 18 from the stop claw 153, the solenoid 20 is driven to a non-energized state. As a result, the shutter 8 rotates 90 ° and stops via the spring clutch 15, so that the non-slit portion 80 of the shutter 8 closes the inlet 12 and the outlet 13 of the developer supply passage.

Therefore, the developer is not supplied to the developing roller 2 and the developing roller 2 is set in a state where development is impossible. Also, in order to notify this state to the control unit of the copying machine main body, a detection switch 202 is provided.
Is inactive. That is, the shutter 8 is 90
By the rotation, the protrusion 154 is displaced from the detection switch 202, and the operating portion of the detection switch 202 is in a non-pressed state. In such a state, the rotation of the developing roller 2 and the like is stopped after all the developer adsorbed on the developing roller 2 is pumped up by the transporting roller 4, and the developing device is in a standby state for performing the next development. In particular, the developer does not remain on the developing roller 2 and is entirely collected via the transport roller 4. That is, the developer is circulated through the circulation path of the developing roller 2, the transport roller 4, and the stirring roller 7, and the stirring roller 7 is disposed in the developer supply path to the developing roller 2,
Is provided, all the developer supplied to the developing roller 2 is collected, and does not remain at the position of the developing roller 2. Incidentally, reference numeral 26 in FIG. 1 denotes a regulating doctor grade for regulating the amount of the developer adsorbed on the developing roller 2.

<Effects> According to the developing device of the present invention, the shutter is provided in the passage for supplying the developer to the developing unit, and the passage is opened and closed. Therefore, the interval between the developing unit and the recording medium is always constant, and the developing condition changes. Without this, accurate development can always be performed.

Further, since the shutter is rotatably provided so as to cover the outer periphery of the stirring means, no extra space is required, the developer can be reliably supplied or closed with a simple configuration, and the entire developing device can be downsized. In addition, since the shutter closes the outlet to the developing section, the developer is not supplied to the developing section via the stirring means, so that the time for collecting the developer in the developing section can be shortened, and the non-development of the developing device can be shortened. Sometimes the latent image formed on the recording medium is not developed.

In addition, when the developer is supplied to the developing unit, the shutter opens and closes the entrance and the developer surely passes through the stirring means, so that the developer can be supplied to the developing unit with sufficient stirring.

[Brief description of the drawings]

1 is a sectional view showing a specific example of a developing device according to the present invention, FIG. 2 is a sectional view showing details of a shutter portion according to the present invention, and FIG. 3 is a diagram relating to drive control of the shutter portion in FIG. It is a side view which shows a drive mechanism. 1: developing tank, 2: developing roller, 3: photoconductor, 7: stirring roller, 8:
Shutter, 9: slit, 12, 13: entrance and exit of developer supply passage, 15: spring clutch, 18: arm, 19:
Spring, 20: solenoid, 152: clutch cover, 15
3: stop claw

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masatoshi Kanegashi 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation (56) References JP-A-61-201278 (JP, A) 25743 (JP, U)

Claims (1)

(57) [Claims] A developing device for developing a latent image formed on the recording medium, the developing device including a developing unit for developing a latent image formed on the recording medium; A developer circulation path is formed by a recovery path for recovering the developer that has completed the above from the developing section, and a partition section dividing the recovery path and the supply path so as to be guided from the recovery path to the supply path. And a stirring means rotatably provided to stir the developer supplied into the supply path divided by the partition, and covering the outer periphery of the stirring means and opening and closing the supply path. A shutter that closes an inlet communicating with the stirring means and an outlet communicating with the developing unit, and a slit that opens, and simultaneously opens the entrance to the supply path. Position and closed position A developing device provided rotatably coaxially with the axis of the stirring means.