JPH01257882A - Electrostatic latent image developing device - Google Patents

Abstract

PURPOSE:To reduce the size of the developing device by shifting the position of the loosed part of a thin film member by the movement of a switching part for switching 1st and 2nd developing devices only by the rotation of a guide member. CONSTITUTION:The cylindrical thin film member 3 which covers a driving roller 2 and a guide member which has an internal surface almost in conformity with the external surface of the driving roller 2 and is arranged on both ends of the driving roller 2 are provided, and 1st and 2nd developing devices 1a and 1b are arranged in parallel. A switching plate 12 is provided which allows the loosed part 3a of this thin film member 4 to contact and leave an electrostatic latent image carrier 100 by the positive shift of the loosed part 3a by the rotation of the guide member 4, and this switching plate 12 is moved to place either of the 1st and 2nd developing devices 1a and 1b in a development state and the other in a nondevelopment state. Consequently, the developing devices are securely switched by rotating the guide members 4 of the developing devices and a driving device is simplified and reduced in size.

Description

[Detailed description of the invention] [Industrial use! ? ] This invention relates to an electrostatic latent image developing device used in electrophotographic copying machines, printers, etc., and more specifically, to an electrostatic latent image developing device using a one-component developer that can easily switch between contact and non-contact with an electrostatic latent image carrier. This invention relates to a multiple development device.

[Prior Art and Problems to be Solved by the Invention] Conventionally, in a multiple development device, a plurality of developing devices are arranged adjacently above and below a photoreceptor drum, which is an electrostatic latent image carrier, and each developing device is It is known that an apparatus is provided with a retracting mechanism to stop and retract a developing device that is not in use. (Refer to Japanese Utility Model Publication No. 55-31557.) However, with these methods, the developing gap between the two developing devices must be made large, and the entire developing device must be moved, which makes the device Or it becomes large.

Furthermore, switching between developing and non-developing in a multiple development device is as follows:
There is a known method in which a solenoid or an electromagnetic clutch mechanism is operated to operate a solenoid or an electromagnetic clutch mechanism to cut the developer in the developing screen-IZ.

However, in this method, 1. If an erroneous signal is generated in the solenoid or electromagnetic clutch due to draughts or noise in the operating circuit before switching the second developing device,
1st. There is always the possibility that the second developing device will enter the developing state at the same time. When multiple developing devices are operated, most of the developer in the downstream developing device is subject to damage. For example, if the first and second developing devices use developers with different polarities, In this case, developer having a different polarity mixes with the developer on the downstream side, and even if normal operation is performed, cuffing occurs when the downstream developing device is used. Also, in a multiple color development device, color mixing may occur.
If a downstream developing device is used, a cloudy color will be developed.

This invention was made in view of these points, and is compact and inexpensive, making it easy to switch between negative-positive (N-p) or positive-positive (p-p) mode.
It is an object of the present invention to provide a compact duplex developing device suitable for a photosensitive drum having a reduced diameter.

[Means for Solving the Problems] The present invention includes a rotationally driven drive roller, a cylindrical thin film member having a circumference slightly longer than the circumference of the drive roller, and a cylindrical thin film member sheathed on the drive roller; The guide member has an inner surface that approximately corresponds to the outer surface shape of the drive roller and is disposed at both ends of the drive roller. A plurality of first and second developing devices that are brought into a developing state are arranged in parallel, and the slack portion of the thin film member is brought into contact and non-contact with the electrostatic latent image carrier by rotation of the guide member. A switching plate is provided to change the position of the guide members of the first and second developing devices, and the amount of relative positional deviation in the rotating direction of the guide members of the first and second developing devices is determined by the switching plate. 1st. This electrostatic latent image developing device is characterized in that one of the second developing devices is in a developing state and the other is in a non-developing state yE.

[Function] Therefore, switching between a plurality of developing devices can be performed reliably by rotating the kite member of each developing device, and the driving device can be easily and compactly formed.

[Example] Hereinafter, the present invention will be described in detail with reference to the drawings. 1st
The figure is a side sectional view showing the configuration of a multiple type developing device according to the present invention. The multiple type developing device 1 is disposed on the side of a photoreceptor drum 100, which is an electrostatic latent image carrier and is driven to rotate in the direction of arrow a.

Since this multiple developing device 1 has developing devices 1a and 1b of the same configuration arranged in parallel, the same members will be given the same reference numerals below, and only one developing device will be described. That is, the lower first developing device 1a is supported on the photoreceptor drum 100 side so that the drive roller 2 can rotate in parallel to the photoreceptor drum 100. This drive roller 2
is formed by covering a conductive member such as aluminum with an elastic member such as rubber, and a developing bias voltage (not shown) is applied to this roller.

The outer periphery of the drive roller 2 is covered with an endless thin film member 3. The thin film member 3 is a toner conveying member, and may be made of, for example, an endless conductive rubber formed into a cylindrical shape. It is formed of a conductive thin film made of metal or a soft resin sheet containing at least ceramics, preferably carbon.

The drive roller 2 equipped with the thin film member 3 is rotatably supported by a case side plate (not shown) and is connected to a drive source (not shown). At both ends of the drive roller 2,
As shown in FIG. 2(A), a semi-annular guide member 4 for bringing the cylindrical thin film member 3 into close contact with the outer peripheral surface of the drive roller 2
．． 4 are inserted. Therefore, both end portions of the thin film member 3 that are pressed by the guide member 4.4 and come into contact with the drive roller 2 are in close contact with the outer peripheral surface of the drive roller 2, and
The extra length of the thin film member 3, which is slightly longer than the circumference of the drive roller 2 [■], is concentrated on the front part of the thin film member 3.
A space S is formed between the drive roller 2 and the outer circumferential surface of the slack part 3a of the thin film member 3 that covers this space S.
- It is adapted to contact the circumferential surface of the ram 100. (See FIG. 1) The coefficient of friction between the outer circumferential surface of the drive roller 2 and the inner circumferential surface of the thin film member 3 is μ1. If the coefficient of friction between the outer circumferential surface of the thin film member 3 and the inner surface of the guide member 4 is R, then R. The relationship is given. Therefore, when the drive roller 2 rotates in the direction indicated by the arrow, the thin film member 3 is also moved in the opening direction, and the outer surface of the slack part 3a of the thin film member 3 covering the space S is opened with an appropriate nip width. It comes into soft sliding contact with the surrounding surface.

By the way, the position of the slack portion 3a of the thin film member 3 can be changed by rotating the kite members 4, 4 at both ends. That is, for example, the thin film member 3 shown in FIG.
When the guide members 4, 4 are rotated clockwise as shown in FIG. 2(B) from the state in which the slack portion 3a of the thin film member 3 is formed in a substantially horizontal lateral direction, the slack portion 3a of the thin film member 3 is You can also position it slightly lower. Therefore, the position of the slack portion 3a of the thin film member 3 is adjusted to the position of the first developing device 1 on the lower side of FIG.
The thin film member 3 may be placed at a position in contact with the circumferential surface of the photoreceptor tram 100 as shown in FIG.
It is possible to easily change the slack portion 3'a of ' to a state in which it is not in contact with the circumferential surface of the photoreceptor tram lOO.

One end of a toner layer thickness regulating member 7 having a metal round bar 6 at the tip is attached to the lid member 5 of the L portion of the driving roller 2.
The metal round bar 6 at the tip of the toner layer thickness regulating member 7 presses against the thin film member 3 that is in close contact with the back of the drive roller 2, thereby forming a thin layer of toner To on the surface of the PIV member 3. The right side of the developer tank 8 is a toner storage tank 8a, in which an agitator 9 that rotates in the direction of arrow C is rotatably provided, and the toner To stored in the toner storage tank 8a is moved in the direction of arrow C. This is to prevent flora kinks and the like while moving in the same direction. Further, at the lower part of the toner layer thickness regulating member 7, toner leveling pads 1 to 10 supported by the frame of the developer tank 8 are provided, and the drive roller 2 is connected through the thin film member 3.
It is designed to come into pressure contact with the

Next, an example of a switching device between the first developing device 1a and the second developing device 1b of the multiple developing device 1 will be explained based on FIGS. 3(A) and 3(B). FIG. 3(A) shows that the lower first developing device 1a in the state shown in FIG. 1 is in an operating state.
When the second developing device 1b on the right side is in an inactive state, FIG. be.

That is, 1st. Guide member 4 of second developing device 1a, lb
, 4' are attached with a pin 11° 11', and a switching plate 12 provided on the side of the drive rollers 2, 2'.
7 are respectively inserted into the vertical guide grooves 13 and 13' so as to be movable in the downward direction. In addition, on the switching plate ■2,
A horizontal extension 14.14' is provided to allow the respective shafts 2a, 2-a of the drive rollers 2, 2' to escape. One end of a connecting rod 15 for moving the switching plate 12 in the left-right direction is pivotally attached to the right center portion of the switching plate 12 by a pin 16. The other end of this connecting rod 15 is one end of a lever 17 rotatably supported by a support shaft 19 or a pin 1.
8, and an electromagnetic plunger 2 is connected to the other end of the lever 17.
0 is connected to the operating rod 20a or pin 21. Also,
The switching device of this example is constructed by hanging between the lower end of the lever 17 and a coiled return spring 22 or a machine frame (not shown).

Therefore, when the electromagnetic plunger 20 is turned off, the operating rod 20a is returned and moved in the direction of the arrow d by the spring 22, the lever 17 rotates clockwise around the support shaft 19, and the connecting rod 15 moves to the right. Then, the switching plate 12 is moved in the direction of arrow e to bring it into the state shown in FIG. 3(A). At this time, the kite member 4.4
Since the pin ' is inserted into the guide groove 13.13' of the switching plate 12, the right movement of the switching plate 12 causes the pin 11 of the kite member 4 to move upward and rotate the kite member 4 counterclockwise. The slack portion 3 of the thin film member 3 of the first developing device 1a on the lower side
A is placed in the developing state in which a is positioned in the horizontal direction and is in contact with the circumferential surface of the photoreceptor tram 100.

At this time, since the pin 11' of the kite member 4' of the second developing device 1b moves downward, the kite member 4' rotates clockwise, and as a result, the slack portion 3a' of the thin film member 3' moves upward. The second developing device 1b is moved to a non-contact state with the photoconductor tram 100, and the second developing device 1b is put into a non-operating state. (1st
(See figure) Next, when the electromagnetic plunger 20 is turned on and its operating rod 20a is driven in the direction of arrow f as shown in FIG. Then, the connecting rod 15 is moved to the left, and the switching plate 12 is moved to the left in the direction of arrow g. Therefore, the pin 11 provided on the guide member 4 of the lower first developing device la moves downward along the guide groove 13 of the switching plate 12, and the kite member 4 moves counterclockwise. Loose part 3a of the thin film member 3 after being rotated
Move it to the lower position. On the other hand, in the second developing device 1b as well, the slack portion 3'+a of the thin film member 3' is
the first developing device 1a.
IE is in an inactive state where the slack portion 3a of the thin film member 3 is not in contact with the photoreceptor drum, and the second developing device lb is in a developing operating state where the slack portion 3'a of the thin film member 3' is in contact with the photoreceptor drum. It is possible to switch to

Next, the operation of the multiple developing device I configured as described above will be explained. This example is an example of a dual-pole developing device with negative-positive and positive-positive polarities.

In FIG. 1, toner To for reversal development having the same polarity as the charging polarity of the photoreceptor tram 100 is placed in the toner storage tank 8a of the first developing device 1a on the lower side. On the other hand, in the second developing device 1b on the second side, a regular developing toner T having a polarity opposite to that of the photoreceptor tram 100 is stored. ' is placed in the toner storage tank 8a. In this figure, the slack portion 3a of the thin film member 3 of the first developing device 1a or the photoreceptor tram 100 is
is in a developing operating state in contact with the peripheral surface of the A drive source (not shown) of the first developing device 1a is activated, and the toner To in the toner storage tank 8a is agitated by the rotation of the agitator 9 in the direction of arrow C, thereby forming the toner T.

The thin film member 3 around the drive roller 2 is supplied in the direction of the thin film member 3 and is prevented from solidifying. Note that the surface of the cylindrical thin film member 3 is processed to have a roughness of about 5 gm in order to improve the conveyance of the toner To. The metal round rod 6 at the tip of the toner layer thickness regulating member 7 presses the drive roller 2 through the thin film member 3 with appropriate pressure, so that the toner To passes between the metal round rod 6 and the thin film member 3. At this time, the toner To is triboelectrically charged, and the toner To is uniformly applied to the surface of the thin film member 3 in a thin layer.

The pressure applied to the metal round rod 6 at the tip of the toner layer thickness regulating member 7 is adjusted so that the layer thickness of the deposited toner To is 20 to 30 gm.

The toner held on the cylindrical thin film member 3 is transferred to the drive roller 2.
The photosensitive drum 10 is moved according to the movement of the driven thin film member 3.
0, the electrostatic potential formed on the surface of the photoconductor tram 100 is removed based on the voltage difference between the surface potential of the photoconductor 1 and the tram 100 and the bias voltage applied to the drive roller 2. It will adhere to the image and form a toner image. Here, the slack portion 3a of the thin film member 3 in contact with the photoreceptor tram 100 is not in contact with the drive roller 2, and can be brought into contact extremely softly and evenly with an appropriate contact width through the space. , a uniform toner image can be formed on the electrostatic latent image on the photoreceptor drum 100.

Further, even if a speed difference is created between the circumferential velocity wave of the photoreceptor drum 100 and the speed of the thin film member 3, once the photoreceptor drum 100
The toner image formed on 0 will not be destroyed.

The toner that has passed through the contact area is continuously conveyed in the direction indicated by the arrow together with the thin film member 3, and the toner consumption pattern that was previously consumed at the contact area on the surface of the thin film member 3 is erased by the toner leveling pad 10, and the surface toner layer is The uniformity of the results will be achieved. Note that this leveling vat 1O contains toner T from the toner storage tank 8a.

It is also designed to prevent backflow of water.

Then, again, the metal Kulin 6 at the tip of the toner layer thickness regulating member 7
The above operation will be repeated.

On the other hand, the upper second developing device 1b is in an inactive state,
Due to the rotation of the guy 1 and member 4, the cylindrical thin film member 3' has a slack portion 3a' separated from the circumferential surface of the upper photoreceptor tram ioo, and is in a position where no development is performed. This separation is formed so that the thin film member 3' is approximately 2 mm away from the circumferential surface of the photoreceptor tram 100, and even if the drive roller 2' is rotating, there is no need for development, and when not developing, the toner Toner It is better to stop driving the second developing device 1b in order to prevent the cylindrical thin film member 3' from being fused to the cylindrical thin film member 3'.

Next, based on FIG. 4, a case will be described in which development is performed using the upper second developing device 1b. in this case,
First, the electromagnetic plunger 20 shown in FIG. 3(B) is actuated, the operating rod 20a is moved in the direction of arrow f, and the lever 17 is rotated counterclockwise to move the switching plate 12 to the left in the direction of arrow g. Then, the slack portion 3 of the thin film member 3 of the first developing device 1a
a is moved downward by the rotation of the guide member 4 and is out of contact with the photoreceptor tram 100, and the second developing device 1b
The slack portion 3a' of the thin film member 3' similarly rotates and comes into contact with the photoreceptor tram 100 in a developing operating state. Toner To' for regular development, which has a polarity opposite to that of the photosensitive drum 100, is placed in the toner storage tank of the second developing device 1b. Therefore, in this case, regular development can be performed by the second developing device 1b in the same manner as in the above example.

Next, a specific example will be described in which development is performed by switching between negative and positive image formation or positive and positive image formation.

Photoreceptor drum: φ50 mm Organic photoreceptor drum surface potential - 400v Charge generation layer - bisazo pigment binder resin Charge transport layer - hydracine derivative binder resin Drive roll φ18mm conductive rubber roll (2mm rubber formed on φ16mm aluminum) Cylindrical thin film Member: φ20mm, thickness 40mm.

Ni electroforming 1 surface roughness 5pLm Toner layer thickness regulating rod/φ1.5mm stainless steel rod Developing high speed 7s: -200V (NP/PP both) Toner: (N
-P) polyester resin + charge control agent (for p-P) styrene acrylic resin + charge control agent Peripheral speed ratio of photoreceptor drum and drive roll = 2 to 4 Process speed: 67 mm/sec.

SLEETSUITE-POLYACETAL The above N-P toner was made by adding a charge control agent to polyester resin, and was successfully negatively charged to the stainless steel rod 6, which is a toner layer thickness regulating member. Also,
The styrene acrylic resin was also used with a charge control agent, and it was successfully negatively charged.

The toner for P-P was made by adding a charge control agent to styrene-acrylic resin, and was positively charged with respect to the stainless steel rod 6, which is a toner layer regulating member. Also, even if Teflon or silicone rubber was used instead of stainless steel, it would still be positively charged. The polarity of the charge changes depending on the charge control agent added.

As described above, by putting toners with different polarities into the first and second developing devices 1a and lb, respectively, a negative image can be produced.
By switching between positive and positive-positive development,
Good development was achieved for both negative and positive images.

The above example is an example of a negative-positive and positive-positive multiple developing device in which the first and second developing devices 1a and 1b contain negative and positive toner, respectively, or the first and second developing devices are Of course, if different color toners are placed in 1a and 1b, the developing device can be used for two-color switching development.

[Effect of the invention] As explained above, the dual development device of the present invention has the first
．． It is possible to reduce the size of the developing device because it is possible to reliably replace the slack portion of the thin film member due to switching of the second developing device or by moving the switching plate with only the rotation of the kite member. It will be done. This switching is mechanically ensured by a switching plate that controls the relative deviation of the rotational position of the guide member, and even if a draught occurs due to an erroneous signal, multiple simultaneous developments will not occur. Therefore, there is no damage to the developer in the downstream developing device, and it is possible to create a multiple developing device that can switch between a plurality of good developments.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the configuration of a multiple development device of the present invention, FIGS. 2A and 2B are perspective views showing the relationship between the drive roller and the thin film member of the first development device, and FIG. Figure 3 (A), (B
) is the first embodiment of the present invention. FIG. 4 is a side view showing the switching device of the second developing device. FIG. 4 is a sectional view showing a state in which the multiple developing device shown in FIG. 1 is switched by the switching device. 1...Double development device la, lb...1st. Second developing device 2.2'
... Drive roller 3.3' ... Thin film member 4.4' ... - Guide member 100 ... Photosensitive drum (electrostatic latent image carrier) Patent applicant Minolta Camera Co., Ltd.

Claims (1)

[Claims] A drive roller comprising: a drive roller that is rotationally driven; a cylindrical thin film member having a circumference slightly longer than the circumference of the drive roller and sheathed on the drive roller; and an inner surface substantially corresponding to the outer shape of the drive roller. and guide members disposed at both ends of the roller, and first and second developing devices that bring the slack portion of the thin film member into contact with or non-contact with the electrostatic latent image carrier to bring it into a developed state or a non-developed state. Arrange multiple in parallel,
A switching plate is provided so that the slack portion of the thin film member comes into contact with and does not come into contact with the electrostatic latent image carrier by changing the position of the slack portion by rotating the guide member. The amount of relative positional deviation in the rotating direction of the guide member is determined by the switching plate, and by moving this switching plate, one of the first and second developing devices can be set in a developing state and the other in a non-developing state. An electrostatic latent image developing device characterized by: