JPH01259381A - Developing device - Google Patents

Abstract

PURPOSE:To prevent a toner bridge formation by a simple constitution by locking a developing device which can move forward and backward freely, to a developing position, and also, applying a vibration to a toner hopper by a hitting member which interlocks with a locking member. CONSTITUTION:When a developing device 2 of a desired color is positioned in a developing position 60a by moving a developing unit 1, a locking means 40 turns through a solenoid 44, a shaft 48 is fitted into a notch 10a of a frame 10 of the unit 1 and its developing device 2 is locked to the developing position. Simultaneously, by interlocking with the means 40 by a hitting plate 49 which has been formed as one body with the means 40, a vibration is applied to a side wall of a toner tank 4c of a toner hopper of the developing device to be locked 2, and a toner bridge formation is prevented satisfactorily without exerting an influence on an image formation by a simple constitution.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a developing device, particularly to a developing device for an electrostatic latent image in an image forming device such as an electrophotographic copying machine or a laser beam printer.

Conventional developing devices for electrostatic latent images use a developer consisting of a two-component mixture of carrier and toner, and replenish the developer tank with toner in proportion to the amount consumed during development. Therefore, toner is stored in a toner hopper.

Incidentally, toner is composed of microparticles on the order of μm, and if left as is, it will adhere to the inner wall of the hopper and cause a crosslinking phenomenon, resulting in incomplete or impossible replenishment.

Therefore, conventionally, various measures have been provided to prevent the crosslinking phenomenon. Generally, a method is adopted in which a diaphragm hits the wall of the toner hopper in a predetermined cycle to vibrate the wall and the toner contained therein (for example, see Japanese Patent Laid-Open No. 184170/1983). ).

However, when the vibrating plate is separately provided in this way, a driving means for the vibrating plate is required, which increases the size of the apparatus, and there are problems in that vibration during the developing operation adversely affects the image. On the other hand, in recent years, various image forming apparatuses equipped with a plurality of developing units have been developed in order to create a color image on a sheet, but it is not preferable to attach a dedicated diaphragm to each developing unit.

SUMMARY OF THE INVENTION An object of the present invention is to apply vibration to the wall of a toner hopper of a plurality of developing devices according to the frequency of use thereof without adversely affecting the formation of images using a striking means having an extremely simple structure, thereby causing toner cross-linking. The aim is to effectively prevent

Means and Function for Solving the Problems In order to solve the above problems, the developing device according to the present invention includes: (a) a plurality of developing devices are provided so as to be movable toward and away from a predetermined developing position of the electrostatic latent image carrier; In the developing device, (b) driving means for advancing and retracting each developing device from a predetermined developing position; (c) locking means for holding the developing device moved to the predetermined developing position at that position; (d) ) A striking member is attached to the locking means and vibrates the wall of the toner hopper of the locked developer in conjunction with the locking operation of the locking means.

For example, a plurality of developing units are installed vertically (elevator type), and by moving the entire unit up and down, any one of them can be moved to a predetermined developing position on the electrostatic latent image carrier and allowed to face it. Alternatively, a plurality of developing units are installed concentrically and on the same side (rotary system), and by allowing rotation of the entire unit, any one of them can be moved to the developing position and made to face each other. The developing device that has been moved to a predetermined developing position is fixed at that position by a locking means. At this time, in conjunction with the locking operation, the striking member collides with the wall of the toner hopper of the locked developing device, that is, the developing device that has been moved to the developing position, and vibrates the wall and the stored toner; Prevent toner crosslinking phenomenon.

EXAMPLE Hereinafter, an example of a developing device according to the present invention will be described with reference to the accompanying drawings.

The developing device in this embodiment is for a color copying machine and is of an elevator type.

That is, as shown in Figures 1 and 2, there are four developing units (2).
The support plate (10) provided between the frames (10) and (10)
11) A developing unit (1) is placed on top of the developing unit (1), and this unit (1) is moved up and down as a whole by a driving means (20) using a stepping motor (21) as a driving source. One developing device (2) is moved to the developing position (60a) of the photoreceptor drum (60) and is opposed to it. 2) is moved to the developing position (60g). The photosensitive drum (60) can be driven to rotate in the direction of arrow (a), and copies are made based on this rotation.

However, since the copying process itself is well known, its explanation will be omitted.

Each developing device (2) has the same configuration and each has a developing sleeve (3), and a magnetic roller (not shown) with N and S poles magnetized on the outer periphery is built into the developing sleeve (3). has been done. The developer is magnetically absorbed into the outer peripheral surface of the developing sleeve (3) in the form of a brush.
The casing (4) is separated into a developer tank (4b) and a toner tank (4c) by a partition wall (4a). is a stirring roller (5), and the toner tank (4c) is a stirring roller (
6) and a toner replenishment screw (7) are each installed so as to be rotatably driven in the direction of arrow (c). The toner is replenished into the developer tank (4b) by the rotation of the screw (7) based on the replenishment signal, mixed with the developer by the rotation of the stirring roller (5>), and then supplied to the outer peripheral surface of the developing sleeve (3). I can do it.

The developer is conveyed in the direction of arrow (b) along the outer circumferential surface of the developing sleeve 3 as described above while the layer thickness is regulated by the height regulating plate (8>), and the electrostatic latent image on the photoreceptor drum (60) is After being subjected to development, it is separated from the developing sleeve (3) and placed in the developer tank (
4b).

By the way, in each of the developing devices (2) installed in four stages, the toner tank (4C) of the developing device (2) in the top stage contains yellow, toner 2,
Magenta color toner is stored in the first row, cyan color toner is stored in the third row, and black color toner is stored in the bottom row, and any one of the color toners is used for development by operating a selection switch on an operation panel (not shown).

Next, the driving means (20), pressure contact means (30), locking means (40) of the developing unit (1), and the striking plate (49) for preventing toner crosslinking will be explained in detail.

In FIG. 2, the driving means (20) is composed of a stepping motor (21) and a timing belt (27) stretched around sprockets (24) and (25), and a flap that holds each developing device (2). t・-mu (10), (10)
The rail (12) provided on the outside of the fixed frame (15)
, (15>) is engaged with the guide rail (16) fixed on the inside of the frame (15>. With this, the developing unit (1>) is movable in the vertical direction, and The fixed bracket (13), (13) is connected to the fixed frame (15), (15) guide (15a), (
15a) and is fixed to the timing belt (27) via a metal fitting (14). The output gear (22) of the stepping motor (21) is the gear (23).
), and the gear (23) is fixed to one end of a support shaft (26) that supports the sprocket (25).

The other end of the spindle (26) is attached to the fixed frame (1) at the back in Figure 2.
5), and another timing belt (not shown) is stretched over it.

The stepping motor (21) is rotationally driven by a drive circuit (not shown), and its rotational force is transmitted through gears (22), (23),
Timing belt (27) via sprocket (25)
) to move the developing unit (1) up and down.

The position of each developing device (2) is detected by a sensor (not shown), and by controlling the rotating plate of the stepping motor (21), any developing device (2) is stopped at a position facing the developing position (60a). be done.

Further, a constant force spring (19) is installed in the fixed frames (15), (15). This constant force spring (19)
The free ends of are fixed to the frames (10), (10),
The driving means (20) lifts the developing unit (1) by constantly outputting a spring force equal to the total weight of the developing unit (1).
The aim is to reduce the driving force.

The locking means (40) locks the developing device (2) which is moved by the driving means (20) to a position opposite to the developing position (60a).
) to lock it in place. In detail, as shown in Figures 1 and 3, the two lock levers (4
1), frame (10) with (41) as spindle (42),
(10), and connects the plunger (45) of the solenoid (44) to the shaft (43) connecting the lower ends of the lock levers (41) and (41) to the wire (4).
6). Lock lever (41
), (41) are tension recoil springs (47), (47
) is biased in the direction of arrow (g), and the shaft (4B>, (48) is equipped with a striking plate (49), (49) at its tip.
is fixed. On the other hand, four notches (10a) corresponding to each developing device 2) are formed on the back side of the frames (10), (10) of the developing unit (1).

Normally, the solenoid (44) is turned off, and at this time, the lock levers (41), (41) are moved by the arrow (g) by the spring force of the tension coil springs (47), (47), as shown by the dotted lines in FIG. ) direction. The driving means (20
) The developer (2) selected in advance by the operator
When the solenoid (44) is turned on and the plunger (45) is retracted, the lock levers (41), (41) are positioned opposite to the developing position (60a).
rotates in the opposite direction to the arrow (g), and the shafts (48) and (48
) is the frame (10), the notch (10a) in (10)
to lock the developing unit (1). at the same time,
Strike plate (49).

(49) is the back part of the casing (4) of the developing device (2);
That is, it collides with the wall of the toner tank (4c). This causes the toner tank (4c) to vibrate, causing the toner adhering to the inner wall to peel off, preventing crosslinking, and as a result, toner replenishment screw (7) is sufficiently covered with toner. , toner supply to the developer tank (4b) is stabilized.

Further, in this embodiment, the pressure contact means (30) for maintaining a constant gap between the developing sleeve (3> and the surface of the photoreceptor drum (60) with respect to the locked developing device (2) as described above. ) is provided.

This pressure contact means (30> is installed on the back of the developing unit (1>) as shown in Fig. 3. In detail, as shown in Figs. 4, 5a, and 5b, (31)
A cam block (32) is supported via a pin (33) in a guide groove (31a) of the cam block (32) so as to be freely movable in parallel.
The cam (35> provided on the support shaft (34) is positioned within the opening (32a) formed in the support shaft (32).
) is rotatably attached to the body frame (17) of the copying machine, and the boot 1 bar 36) and belt (3
7> to rotate in one direction.

On the other hand, each developing device (2) is marked with an arrow (d) on the support plate (11).
.

The developing sleeve (3) is installed so as to be slidable in the direction (d').
) is engaged with the notch (50a) of the regulating plate (50). This regulation plate (50) is rotatably attached to a pin (51), is always biased in the direction of arrow (e) by a tension coil spring (52), and has a stopper pin in the direction opposite to arrow (e). The position is regulated by (53). Further, a spring plate (54) is installed on the back side of the casing (4) of each developer (2), and the developer (2) is engaged with the cam block (32) via the spring plate (54). are doing.

In the above configuration, normally, as shown in FIG. 5b, the cam (35> is in contact with the left edge of the opening (32a) of the cam block (32), and the regulating plate (50) is in tension with the tension coil spring (5).
The developing device (2) rotates in the direction of arrow (e) with the biasing force of (2).
moves in the direction of arrow (d'), and the developing sleeve (3) is set in a retracted state from the surface of the photosensitive drum (60). The developer preselected by the operator (
2> is driven by the photosensitive drum (6) by the driving means (20).
0) to a position opposite to the developing position (60a),
After being locked by the locking means (40) and applying vibration to the toner tank (4c), the support shaft (34)
is rotated 180° in the direction of arrow (f) together with the cam (35), the cam (35> comes into contact with the right edge of the opening (32a), and the cam block (32) moves in parallel in the direction of arrow (d). With this, the developing device (2) moves through the spring plate (54) and against the spring force of the tension coil spring (52) as shown by the arrow
d) move forward in the direction. This forward movement is regulated by the regulation plate (50) coming into contact with the stopper bin (53), and the gap between the developing sleeve (3) and the surface of the photosensitive drum (60) is accurately positioned (No. 5a). (see figure).

A series of operations of each member in this embodiment is controlled as follows. First, when a developing device switching signal is issued, the stepping motor (21) is driven to move the preselected developing device (2>) to a position opposite to the developing position (60a).Next, the solenoid (44) is turned on, the developing unit (1) is locked with the lock lever (41), and the toner tank (4c) is vibrated with the striking plate (49).Next, the cam (35) is rotated 180 degrees, and the developing unit (1) is turned on. The developing sleeve (3) of the device (2) is brought close to the surface of the photoreceptor drum (60). In this state, the electrostatic latent image formed on the photoreceptor drum (60) is developed. After development teeth,
First, the cam (35) returns and the developing device (2) moves to the developing position (
60a), the solenoid (44) is turned off,
The lock will be released.

As described above, in this embodiment, each time the developing device (2) is switched, the striking plate (49) collides with the toner tank (4c) in conjunction with the locking operation, and the prevents cross-linking of In this case, vibration is applied by the striking plate (49) only when switching the developing device, and the toner tank (4c) does not vibrate during the developing operation, so that the crosslinking prevention operation does not adversely affect image formation. Moreover,
The more a developer can be used, the more frequently the crosslinking prevention operation is performed, and stable toner replenishment can be achieved. In addition, the striking plate (4
9) is attached to the existing lock levers (41), (at), so it does not require any dedicated support member or drive means, and is extremely simple in structure.

It should be noted that the developing device according to the present invention is not limited to the above embodiments, and can be variously modified within the scope of the gist.

In particular, the developing device may be switched by a rotary type instead of an elevator type, and a driving means (20) and a pressure contacting means (30) are used.
The locking means (40) can also have various configurations.

As is clear from the above explanation, according to the present invention, the wall of the toner hopper of the developing device that has been allowed to move to the developing position is vibrated by the striking member in conjunction with the locking operation for the developing device. As a result, it is possible not only to prevent the toner cross-linking phenomenon and achieve stable toner replenishment, but also to use the locking means as the supporting means and driving means for the striking member, resulting in a very simple structure. Moreover, the application of vibration is performed at the same time as locking, so that vibration is not induced during image formation and does not adversely affect image formation. Further, the more frequently used the developing device is, the more vibrations are applied, and the crosslinking prevention operation is performed more efficiently.

[Brief explanation of the drawing]

The drawings show an embodiment of the developing device according to the present invention, in which FIG. 1 is a vertical sectional view of the entire device, FIG. 2 is a front perspective view of the entire device, and FIG. 3 is a rear perspective view of the entire device. FIG. 4 is a perspective view of the pressing means, and FIGS. 5a and 5b are illustrations of the pressing operation of the developing unit. (1)...Developing unit, (2)...Developing device, (4
c)... Toner tank, (15)... Fixed frame, (
20)...Drive means, (21)...Stepping motor, (,27)...Timing belt, (40)...
... Locking means, (41) ... Lock lever 1 (44
〉...Solenoid, (49)...Blow plate, (60)
. . . Photosensitive drum, (60a) . . . Development position.

Claims (1)

[Scope of Claims] 1. In a developing device in which a plurality of developing devices are provided so as to be movable relative to a predetermined developing position of an electrostatic latent image carrier, a driving means for moving each developing device forward and backward relative to a predetermined developing position. a locking means for holding the developing device moved to a predetermined developing position at that position; and a locking means attached to the locking means and configured to vibrate the wall of the toner hopper of the locked developing device in conjunction with the locking operation of the locking means. A developing device comprising: a striking member for applying a blow;