JPH01108571A - Developing device - Google Patents

Abstract

PURPOSE:To entirely recover toner by forming a magnetic pole in a developing roll so as to be turnable in a peripheral direction by a prescribed angle, and also, providing a magnetic pole moving means. CONSTITUTION:At the time of recovering a toner in a developer on a developing roll before changing a color, when a magnetic pole positioned at the upstream side in the carrying direction of the developer from a napping height control member 39 is moved to the napping height control member 39 by a magnetic pole moving means, magnetic force works more strongly on the developer in a stirring chamber 38 detained by the napping height control member 39. Accordingly, even if magnetic restraint between carriers becomes strong due to the decrease of the toner concentration, the developer does not remain behind but flows and the stirring property is improved. In such a way, the toner does not remain behind but recovered entirely to an electrostatic latent image carrier side or a toner supplying means side by a usual toner recovering operation.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to an image forming apparatus using an electrophotographic copying process;
The present invention relates to a powder development type developing device capable of changing colors, which is used, for example, in copying machines, printers, and the like.

(Prior Art) Conventionally, this type of developing device includes a developing roller in which a plurality of magnetic poles are arranged along the inner circumferential surface, and a toner supply means for supplying toner onto the outer circumferential surface of the developing roller. An electrostatic latent image is developed by rubbing a magnetic brush of a developer made of toner and carrier formed on a developing roller against an electrostatic latent image carrier, and multiple toner supply means are used for a single developing roller. It is possible to change the color of an image by providing different color toners and selecting appropriate toner supply means.

Then, a 21st
As shown in Fig. a, a brush height regulating member (39) close to the developing roller (32), and a developer stirring chamber (38) located upstream of the brush height regulating member (39) in the developer transport direction. The brush height regulating member (39) dams a part of the developer conveyed in a magnetic brush state on the developing roller to regulate the amount of developer conveyed, and the brush height regulating member (39) 39), the developer that is dammed up and the developer that flows in later form a swirling flow to agitate the developer and promote frictional contact charging between the toner and the carrier.

When changing the color by selecting the toner supply means, if the previous toner remains in the developer on the developing roller, new toner of a different color will be supplied and color mixing will occur.
Prior to color change, the I/toner in the developer on the developing roller is removed and recovered. This two-time rough toner removal operation involves either supplying the toner on the developing roller to the electrostatic latent image carrier, that is, developing and removing the electrostatic latent image, or collecting the toner on the developing roller to the toner supply means side. It is done by doing.

(Problems to be Solved by the Invention) However, as the toner in the developer on the developing roller is collected, the toner concentration in the developer decreases and the magnetic binding force between the carriers becomes stronger. As shown in
Stirring chamber (38) before being regulated by the hot height regulating member (39)
The agitation performance of the developer deteriorates and some of the developer stops flowing, causing a delay in collection of the toner in that part or leaving it uncollected.

The toner remaining without being collected in this way may mix with toner of a different color after the color change, resulting in a cloudy image. There have been problems such as falling onto the developer on the developing roller due to vibration etc., resulting in an image with a drop pattern, or falling outside the developing device, causing adverse effects.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a developing device that can ensure the agitation of the developer on the developing roller and completely recover the toner.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides a single developing roller having a plurality of magnetic poles arranged along its inner peripheral surface, and a single developing roller having a plurality of magnetic poles arranged along its inner peripheral surface, and a single developing roller having a plurality of magnetic poles arranged along its inner peripheral surface. A plurality of toner supply means supplying toner of different colors, and a two-component developer disposed close to the developing roller to regulate the conveyance amount of a two-component developer consisting of toner and carrier conveyed in a magnetic brush state on the outer circumferential surface of the developing roller. In the developing device, which is equipped with a brush height regulating member and a stirring chamber provided upstream of the spike height regulating member in the developer transport direction, and is capable of changing colors by appropriately selecting the toner supply means, The magnetic pole in the developing roller is formed to be rotatable in the circumferential direction at a predetermined angle, and when collecting the toner in the developer on the developing roller before color change, the magnetic pole is formed so as to be rotatable in the circumferential direction at a predetermined angle, and when collecting the toner in the developer on the developing roller before color change, A magnetic pole moving means is provided for moving the magnetic pole located on the side toward the ear height regulating member.

(Function) Therefore, according to the above configuration, when collecting toner in the developer on the developing roller before color change, as shown in FIG. 210, the brush height regulating member (39
), when the magnetic pole located on the upstream side in the developer transport direction is moved toward the ear height regulating member (39) (to the state shown by the two-dot chain line in the figure), the magnetic pole is blocked by the ear height regulating member (39). Since a stronger magnetic force acts on the developer in the stirring chamber (38), even if the magnetic binding force between the carriers becomes stronger due to a decrease in toner concentration, the developer flows without stagnation and improves stirring performance. The toner is completely collected on the electrostatic latent image carrier side or the toner supply means side by a normal toner collection operation without remaining.

(Example) Hereinafter, the present invention will be described with reference to the accompanying drawings showing one example thereof.

A. General Structure and Operation of Copying Machine FIG. 1 is a sectional view of a small-sized copying machine equipped with a developing device according to the present invention, and its structure will be explained together with its operation.

The main body (1) of the copying machine has an electrostatic capacitor made of a cylindrical body (for example, 30 mm thick) made of aluminum, with selenium, zinc oxide, cadmium sulfide, or other organic photoconductors deposited or coated on the surface. Photosensitive drum (latent image carrier)
3) is located.

This photosensitive drum (3) is rotated in the direction of arrow (a) by the main motor (2) driven by the ON operation of a print switch (not shown), and the surface is heated to a predetermined level by the discharge of the electrostatic charger (4). charged to a potential.

In the optical system (8), an exposure lamp (9) is turned on, and the light is irradiated onto a document (not shown) placed on a document table (14) that scans in the direction of arrow (b), and the reflected light is The photoreceptor drum (3), which is charged to a predetermined potential as described above, is exposed to light from the exposure point (Xi) through the Selfox lens array (12), and the original image is displayed on the surface of the photoreceptor drum (3). An electrostatic latent image corresponding to the image is formed. This electrostatic latent image is supplied with toner at a portion (X2) facing the developing device (5) and is visualized as a toner image. Note that this developing operation will be explained in detail later.

Copy paper (S) is fed from the paper feed section (20) to the paper feed roller (2■)
is fed one by one based on the rotation of the guide plate (22X
23), waits in front of the timing roller pair (24), and moves the transfer area (
x3), and the toner image is electrostatically transferred based on the discharge of the transfer charger (6).

The copy paper (S) onto which the toner image has been transferred is placed on the photosensitive drum (
After being separated from the surface of the copy paper (S), the toner image is transported by a transport belt (25) via a guide plate (26) to a fixing device (27), where the toner image is fused and fixed onto the copy paper (S). The paper is discharged onto the paper discharge tray (28).

The cleaning device (7) removes residual toner from the surface of the photosensitive drum (3) that has passed through the transfer area (X3), and then the light from the exposure lamp (9) passes through the opening (10) of the reflective shade (10). 11) and a mirror (13) to irradiate the region (X4) to remove residual charges.

B. Structure, etc. of the developing device (5) Next, the structure, etc. of the developing device (5) according to the present invention will be explained in the following order with reference to FIGS. 2 to 15.

i, Schematic configuration of developing device (5) ■, Developing section (30) ■, Switching mechanism (41) iv, Vibration mechanism (47) v, Toner hopper (60X70) vi, Opening/closing mechanism (80) vii, Gap adjustment mechanism ( 90) Shaft, lock mechanism (100) ix, drive mechanism (120) As shown in FIG. 1.2, roughly speaking, there is a first toner hopper (60) that accommodates black toner, a second toner hopper (70) that accommodates color toner other than Shofu (for example, red toner), and a photoreceptor. The drum (3) moves in the directions of arrows (c) and (c') along the outer peripheral surface of the drum (3), selectively receives toner from the toner hopper (60) or (70), and transfers the toner to the photoreceptor drum (3). and a developing section (30) that supplies the electrostatic latent image formed on the surface of the image forming apparatus.

U, developing section (30X, see Figure 3.4) In the developing section (30), developing frames (31), (3
1) (one not shown) is the photosensitive drum support shaft (16)
It is rotatably attached to the back and front sides of the

The developing frames (31), (31) are equipped with a developing roller (32).
) is supported by a method described later, and a predetermined gap is formed between the developing roller (32) and the photosensitive drum (3).

Note that the developing roller (32) has an outer diameter of 116 mm, for example.
conductive, non-magnetic aluminum cylindrical body with micro-recesses (depth 10 to 200 μm) formed on the outer peripheral surface by blasting, etc., or a resin or oxide film formed on the surface of the aluminum cylindrical body. An insulating or semi-insulating material, or one in which an organic polymer film is plasma-polymerized on the surface of an aluminum cylinder by glow discharge in a vacuum is used.

Inside the developing roller (32), there are magnetic poles (33a) in the axial direction.
), (33b), (33c), (33d), (33e)
A magnetic roller with multiple extended magnets arranged circumferentially (
33), one end of the spindle is rotatably supported in a bearing recess (not shown) formed inside the developing roller (32), and the other end (34) of the spindle is rotatably supported by a bearing recess (not shown) formed inside the developing roller (32). (3
2) and the developing frame (31) and is rotatably supported. On the other hand, one end of the developing roller (32) is rotatably supported by the developing frame (31), and the other end is rotatably supported by the spindle of the magnetic roller (33).

Therefore, even if the developing section (30) moves along the outer peripheral surface of the photoreceptor drum (3), the magnetic pole of the magnetic roller (40) maintains a constant positional relationship relative to the photoreceptor drum (3). be. That is, the magnetic pole facing the photosensitive drum (3) always faces the photosensitive drum (3).

Further, between the developing frames (31), an upper frame (35) and a lower frame (36) made of a non-magnetic conductive material cover the upper and lower parts of the developing roller (32), respectively.
) is bridged, and the developing roller (32) is connected to the photoreceptor drum (
3) and only the opposite side thereof is open.

Then, this upper frame (35) and lower frame (
The surface facing the developing roller (32) of 36) is formed so that the developer conveyed on the developing roller (32) in a magnetic brush state is always in contact with the surface, and the surface of the magnetic brush facing the magnetic pole is particularly high. A recess (35a) is formed to prevent developer from clogging.

An end member (36b) is attached to the tip of the lower frame (36) on the side facing the photosensitive drum (3) via an insulating material. Further, on the surface of the lower frame (36) facing the developing roller (32), a stirring chamber (
38) is formed, and the inner surface of the stirring chamber (38) is a curved surface that allows the developer to flow smoothly without stagnation,
The side wall of the stirring chamber (38) on the downstream side in the developer transport direction is
A height regulating portion (39) faces the developing roller (32) with a predetermined gap therebetween.

As shown in FIG. 18, the magnetic roller (33) is movable by a magnetic pole moving mechanism (37). That is, the spindle (34) of the magnetic roller (33) is
It is driven by a solenoid (SL) via a lever (37a) and a link member (37b), and returned by a spring (37c).

First, when the solenoid (SL) is off, as shown in FIG. 17, the main developing pole (33a) of the magnetic roller (33)
is located on the line connecting the spindle (34) of the magnetic roller (33) and the spindle (16) of the photoreceptor drum (3), and is on the upstream side of the height regulating member (39) in the developer transport direction. The magnetic pole (33b) located in the magnetic roller (33), that is, the magnetic pole (33b) facing the stirring chamber (38)
4) and the height regulating member (39) at an angle α toward the upstream side in the developer transport direction.

Next, when the solenoid (SL) is turned on, the magnetic roller (33) rotates counterclockwise in FIG. 17 by an angle θ, and the magnetic pole (33b) facing the stirring chamber (38) It is configured to stop at a position separated by an angle β from a line connecting the support shaft (34) of (33) and the height regulating member (39) upstream in the developer transport direction.

By the way, the end member (36b) of the lower frame (36)
) is connected to the positive pole of the DC power supply, and a positive toner adhesion prevention bias voltage (vL) is applied thereto. Also, a developing roller (32).

The upper frame (35) and lower frame (36) are connected to a DC power source via a bias changeover switch (SW).

At position 1 of this bias changeover switch (SW), a negative developing bias voltage (Vb) is applied to the developing roller (32), and the upper frame (35)
A voltage having the same potential as that of the developing roller (32) is applied to the lower frame (36) excluding the end member (36b). Also, at position 2, the developing roller (32
) is applied with a negative developing bias voltage (vb), and a positive voltage, that is, with the same polarity as the toner, is applied to the lower frame (36) excluding the upper frame (35) and the end member (36b). There is. Further, at position 3, a positive developing bias voltage (vb) is applied to the developing roller (32), and the lower frame (excluding the upper frame (35) and end members (36b))
36) is also applied with a positive voltage, that is, with the same polarity as the toner.

Table 1 is a list of the polarities of the voltages applied to each of the above members.

Additionally, a developing section (30) is provided above and below the developing section (30), respectively.
The switches (S l ) and (S 2 ) for detecting are attached.

As shown in Fig. 3, the developing section (30) having the above configuration is provided with the photosensitive drum (3), the charger (4), and the cleaning device (7) at the rear and front sides of these. The entire imaging unit (
The imaging unit (IU) is configured to be detachable from the copying machine main body (1).

The developing section (30) having the above configuration has a switching mechanism (41
), a vibration mechanism (47), etc. are attached, and these will be explained below.

Stone, switching mechanism (41X see Figure 4.5) switching mechanism (4I
) moves the developing section (30) along the outer peripheral surface of the photoreceptor drum (3), and changes the thermal development state (Pl) and the color development state (
P2).

In this switching mechanism (41), a switching lever (42) is fixed to the developing frame (31) of the developing section (30),
A toner hopper (60) is attached to the switching lever (42).

A plate (43) located on the top surface of (70) is a lock. Further, a window (44) is formed in the plate (43), and the lever 42) is rotated in the direction of arrow (c).
When the developing roller (32) is switched to the heat developing state (Pl) where it faces the supply roller (63) of the first toner hopper (60), the black mark provided on the upper surface of the toner hopper (60) is displayed in the window (44). (45) appears.

Conversely, by rotating the lever (42) in the direction of the arrow (C'), the developing roller (32) moves along an arc (Ll) with its center centered on the photoreceptor drum (3),
When switching to the color development state (P2) in which the developing roller (32) faces the supply roller (73) of the second toner hopper (70), the toner hopper (70) is placed in the window (44).
) so that the color mark (46) provided on the top surface appears.

Then, a black mark (45) or a color mark (46) appears through the window (44) on a display section (not shown) provided on the copying machine main body (1), and whether the copy is a silent image or a color developed copy is displayed. Displays whether it is possible.

iv. Vibration mechanism (see 47X Figure 6) The vibration mechanism (47) uses the switching mechanism (41) to switch the developing section (30) between the thermal development state (Pl) and the color development state (Pl).
P2) and the upper and lower frames (3).
5) and (36), thereby peeling off toner mechanically or electrically adhered to the inner surface of the frame.

This vibration mechanism (47) includes a spring vibrator (48),
(52) are each provided with a striking portion (50) on the photoreceptor drum (3) side.
), (54), is swingably supported by the upper frame (35) and lower frame (36) via fulcrums (49) and (53), and is supported in one direction by springs (51) and (55). is energized by Further, the support shaft (1) of the photoreceptor drum (3) is attached to the frame (57) provided on the copying machine body (1).
An uneven portion (56) is continuously formed on an arc centered at 6), and a vibrator (48) is located there.

The outer end of (52) is engaged.

Therefore, when the lever (42) of the switching mechanism (41) is held to switch the developing section (30) from the thermal development state (Pi) to the color development state (P2) or vice versa, the vibrator (48) ), (52) are repeatedly engaged with and released from the concavo-convex portion (56), causing the vibrators (48), (52) to vibrate, thereby causing the upper portions of the striking portions (50), (54) to The outer parts of the frame (35) and lower frame (36) are struck to give them vibration.

v, Toner hopper (60), (70X, see Figure 7)
The toner hoppers (60) and (70) supply black toner and color toner to the developing section (30), respectively.

These toner hoppers (60) and (70) are connected to the developing section (30).
) is removably located at the rear of the toner hopper (
At the front of the main bodies (61) and (71) of 60) and (70), there are supply rollers (63) in the openings (62) and (72).

(73) are arranged, and the respective supporting shafts (68), (78) are provided in the main bodies (61), (71) with bearings (94), (95).
X (see Figure 1O) is rotatably supported. Also,
The centers of the supply rollers (63) and (73) are located on an arc (L2) centered on the photoreceptor drum (3),
At a position where the outer peripheral surfaces of the supply rollers (63), (73) and the photosensitive drum (3) are closest to each other, the distance therebetween is slightly larger than the outer diameter of the developing roller (32).

The supply rollers (63) and (73) have an outer diameter of 116 mm, for example, and have a depth of 10 to 20 mm by blasting, etching, or rotting on the outer peripheral surface.
A cylindrical body made of conductive, non-magnetic aluminum or the like is used in which a minute recess of 0 μm is formed.

Also, the openings (62) of the toner hoppers (61), (71)
), (72) are provided with regulating blades (64), (74) and toner outflow prevention films (65), (75), the tips of which are attached to the rear outer peripheral surfaces of supply rollers (63), (73). are pressed into contact with each other.

The rear portions of the toner hoppers (60) and (70) are provided with the supply rollers (63) and (73), and the regulation blades (64) and (7).
4) and toner outflow prevention films (65) and (75) to form toner storage tanks (66) and (76), respectively, and toner storage tanks (6) of the first toner hopper (60).
6) rotatably accommodates a stirring blade (67).

Note that the switches (S3) and (S4) are switches that detect whether or not the black Naho Shiba (60) and (70) are installed in the predetermined positions, respectively, and the signals are output to a control device (not shown). It has become so.

vi, opening/closing mechanism (see 80X Figure 7.8) opening/closing mechanism (80X)
0) is the opening (
62) and (72) are opened and closed to cut off the supply of toner from an unused toner holder and prevent the toner from falling.

This opening/closing mechanism (80) includes a supply roller support shaft (68),
Frame (81x81) on both ends of (78), (85)
(85) is rotatably supported, and the frame (85) is rotatably supported.
81X81) and (85X85) respectively have opening/closing force
(82) and (86) are bridged.

The frames (81) and (85) are each integrally provided with segment gears (83) and (87), and are moved in the closing direction [arrow (d)] by springs (84) and (88).

(e) direction)]. The springs (84), (88) are wound around the support shafts (68), (78), one end is locked to the main body (61), (71), and the other end is connected to the frame (81), ( 85) respectively.

On the other hand, a segment gear (89) is integrally provided in the developing frame (31) of the developing section (30), and this segment gear (89) has a
) meshes with the segment gears (83) and (87) of
When set to P2), either one of the openings 2O- (62) or (72) is opened.

More specifically, when holding the lever (42) of the switching mechanism (41) and rotating the developing section (30) and the segment gear (89) in the direction of the arrow (C) to set the black developing state (Pl), ( solid line state in Fig. 8), the segment gear (89)
segment gear (83) as it moves.

(87) rotate in the directions of arrows (d') and (e), respectively, and as shown in FIG. is opened, and the opening (72) of the second toner hopper (70) is closed with the opening/closing cover (86).

When holding the lever (42) and rotating the developing section (30) and the segment gear (89) in the direction of the arrow (C') to set the color developing state (P2) (the state shown by the two-dot chain line in Fig. 8),
Segment gears (83) and (87) are respectively indicated by arrows (d)
, (e″) direction, and the first toner hopper (60
) is closed with an opening/closing cover (82),
The opening/closing cover (86) of the second toner hopper (70) is retracted and the opening (72) is opened.

vii, gap adjustment mechanism (see 90X Figure 9.10)
The gap adjustment mechanism (90) adjusts the distance (
gear) is set to a predetermined value.

In this gap adjustment mechanism (90), the developing roller (32
) has gap adjustment rollers (91) on both ends of the support shaft (33).
is rotatably provided. In addition, the supply roller support shaft (68
), (78) have gear/knob adjustment rollers (92) at both ends, respectively.
) and (93) are rotatably provided.

On the other hand, the supply roller bearings (94) and (95) formed on the side walls of the toner hopper bodies (61) and (71) have a slightly larger diameter than the supply roller support shafts (68) and (78). A gap is formed between (68), (78) and the bearing (94), (95).

Further, stoppers (96) and (97) are formed on the side walls of the toner hopper bodies (61) and (71), and the stoppers (
Springs (98), (99) are interposed between the support shafts (68), (78) and the support shafts (68), (78).
8) and (, 78) are biased toward the developing section (30) in the direction of the arrow.

According to the gap adjustment mechanism (90) having the above configuration, as shown in FIG. 9, when the developing roller (32) is in the thermal development state (PL), the first gap adjustment roller (91) Gap adjustment roller (92) of toner hopper (60)
) are pressed into contact with each other, and the developing roller (32) and the supply roller (63
) A predetermined gap is set between the two.

When the developing roller (32) is switched to the color developing state (P2), the gap adjustment roller (91) of the developing roller (32)
) is the second toner hopper (70) gap adjustment roller (
93), and the developing roller (32) and supply roller (
73), a predetermined gap is set between the two.

vij, locking mechanism (100X, see Figures 11-13) The locking mechanism (100) locks the first toner hopper (60) when the developing section (30) is in the thermal development state (PI), and the color developing unit When in state (P2), the second toner hopper (70) is locked.

In this locking mechanism (100), the developing frame (31)
Lock release parts (lO1) and (IO2) are provided on the outer surface of -23=, and the surface of the release part (lOl) [the surface facing the stopper (103) described below] is in the direction of arrow (c). The surface of the release portion (102) [the surface facing the stopper (104)] slopes upward in the direction of the arrow (C'').

On the other hand, the copying machine main body (1) is provided with stoppers (103) and (104) located on the sides of the toner hoppers (60) and (70), as shown in Fig. 12.13. The rear part is fixed to the copying machine main body (1) via fixing members (105) and (lO6), and stoppers (103) and (lO6).
The free end of O4) has retaining holes (107) and (108).
are formed respectively. Also, a toner hopper (60), (
The main bodies (61) and (71) of the supply roller (63)
), (73), the retaining holes (107), (1
Engagement protrusion (109), (l l O) having approximately the same diameter as 08)
is formed.

In the locking mechanism (100) having the above configuration, the 11th
As shown in the figure, the developing frame (31
) is set to the heat development state (Pi), the release section (
102) slips into the tip of the stopper (104), the retaining hole (108) of the stopper (104) is released from retaining protrusion (l l O) of the second toner hopper (70), and the toner hopper ( 70) is removable (see FIG. 13). On the other hand, as shown in FIG. 12, the stopper (103) of the first toner hopper (60) is in pressure contact with the side surface of the developing frame (31), so that the stopper (103) is in contact with the engaging hole (L O7).
engages with the engagement protrusion (lO9), and the first toner hopper (60) is locked in a non-removable state.

Hold the lever (42) of the switching mechanism (41) and turn on the developing section (3).
0) to the color development state (P2), the release part (101) sinks into the surface facing the stopper (103) and the first toner hopper (60) is set in a removable state, contrary to the above. and the release part (102) is pressed against the stopper (
The second toner hopper (7) is evacuated from the opposite part of the
0) or locked.

That is, when the developing section (30) is in the thermal development state (Pl), the first
The second toner hopper (60) is locked and cannot be taken out, and only the second toner hopper (70) is set to be removable. On the contrary, the developing section (30) or the color developing state (
At the time of P2), the second toner hopper (70) cannot be taken out, and only the first toner hopper (60) is set to be removable.

ix, drive mechanism (120X, see Figure 14.15) In the drive mechanism (1, 20), the support shaft (
The photoreceptor drum drive gear (121) provided at 16) is drivingly connected to the main motor (2) (see Figure 1).
The developing roller drive gear (122) attached to the support shaft of the developing roller (32) is configured to rotate around the photosensitive drum drive gear (121) while meshing with it via the developing frame (31). (121) and (1
22) constitutes a differential gear device. Note that the developing roller drive gear (122) and the photosensitive drum drive gear (121)
) has a gear ratio of 1:2.

Note that the developing roller drive gear (122) is a one-way clutch (
131) to the supporting shaft. This one-way clutch (131) is configured so that when the developing roller drive gear (122) rotates clockwise when viewed from the left side in FIG. 20, the rotational torque is transmitted to the spindle of the developing roller (32). It has become.

Also, the support shaft (68) of the supply rollers (63) and (73).

Supply roller drive gears (124) and (126) are attached to (78) via a supply roller drive clutch (clutch corresponding to supply roller (73) 127X is not shown), and these supply roller drive gears (124), (1
26) mesh with idler gears (123) and (125), respectively.

Further, although not shown, the stirring blade (67) provided in the first toner hopper (60) is connected to the supply roller drive gear (12).
4) so as to rotate together with the supply roller (63). Note that the stirring blade (67) may be connected to the drive system of the document table (14) so that it rotates as the document table moves.

In the drive mechanism (120) having the above configuration, the developing section (
30) is set to the black development state (PI), as shown in FIG. It meshes with the gear (123).

Therefore, when the main motor (2) is driven in this state and the photosensitive drum drive gear (121) rotates in the direction of the arrow, the developing roller drive gear (I22), idler gear (123), and supply roller drive gear ( 124)
rotate in the directions of the arrows, and the photosensitive drum (3) and the developing roller (32) rotate in the directions of the arrows, respectively. Further, when the supply roller drive clutch (127) is turned on by a signal from a control device (not shown), the supply roller drive gear (127) is turned on.
24) is transmitted to the supply roller (73).

When the developing section (30) is switched from the black developing state (Pi) to the color developing state (P2), the developing roller drive gear (12
2) moves along the circumference of the photosensitive drum drive gear (121) while meshing with it, and meshes with the idler gear (125) of the second toner hopper (70).

Therefore, when the main motor (2) is driven in this state and the photosensitive drum drive gear (121) rotates in the direction of the arrow, the developing roller drive gear (122), idler gear (125), and supply roller drive gear are rotated accordingly. (126
) rotate in the directions of the arrows, and the photosensitive drum (3) and the developing roller (32) rotate in the directions of the arrows, respectively. Further, when the supply roller drive clutch (not shown) is turned on, the rotation of the supply roller drive gear (126) is controlled to the supply roller (73).
transmitted to.

X, Speed change mechanism (130X, Fig. 19) The developing roller (32) can change its rotational speed by a speed change mechanism (130) using an electromagnetic clutch.

That is, a first speed change gear (133) having a friction plate (132) is loosely fitted onto the support shaft (16) of the photoreceptor drum (3) while being supported by a plate spring (not shown). A clutch (135) including a clutch plate (134) facing a friction plate (132) of a transmission gear (133) is loosely fitted to a support shaft (16) with the support of a stopper portion (not shown). In addition, the clutch plate (134) is attached to the support shaft (16) in the circumferential direction.
) is fitted to be able to rotate integrally with the developing roller (32).
A second speed change gear (136) that meshes with the first speed change gear (133) is fixed to the support shaft, and the gear ratio of the second speed change gear (136) and the first speed change gear (133) is l:2.3. It becomes.

The clutch (135) moves the friction plate (132) shown in Fig. 19 by a signal from a control system (not shown).
134) direction, and as a result, the first transmission gear (13
The friction plate (132) of 3) is in pressure contact with the clutch plate (I34), and the rotational torque of the support shaft (16) is transferred to the first gear (13).
3).

In the transmission mechanism (130) having the above configuration, the clutch (135) is in the FF state during development, and when the photoconductor drum drive gear (121) rotates due to the drive of the main motor (2), the clutch (135) is in the FF state. The photosensitive drum (3) and the clutch plate (134) rotate in the direction of the arrow in the figure via the shaft (16), and the developing roller drive gear (12
2) and the one-way clutch (131), the developing roller (32) rotates in the direction of the arrow in the figure. This developing roller (
32), the second transmission gear (136) also rotates in the same direction, but the friction plate (132) is not connected to the clutch plate (134).
Since the first speed change gear (133) meshing with the second speed change gear (136) rotates idly with respect to the support shaft (16).

Next, when the clutch (135) is activated during toner collection, the photosensitive drum drive gear (12) is transferred from the main motor (2).
1) is directly transmitted from the photoreceptor drum drive gear (121) to the development roller (32) via the development roller drive gear (122) and one-way clutch (131).
), and a route from the clutch (135) to the developing roller (32) via the first gear (133) and second gear (136). Since the gear ratio is higher, the developing roller (32) receives rotational torque through the latter route and rotates at a higher speed than during development, and as a result, the one-way clutch (1
31), the developing roller drive gear (122) idles.

xi. Toner density control means (see FIG. 2) Next, the toner density adjustment means supplied to the developing section (30) will be explained.

As described above, the developing bias voltage (vb) is applied to the developing roller (32) of the developing section (30) via the bias changeover switch (SW), and the developing roller (32) of the developing section (30) is
) has a DC bias (Vss) and an AC bias (Vrm
s) connected in series is applied, and the bias voltages (V b) and (V ss) are variable, and by adjusting the voltage value, the toner concentration on the developing roller (32) can be adjusted. is adjustable.

X■, Developer In the developing device (5) having the above structure, a two-component developer consisting of toner and carrier is used.

As the carrier, a binder type carrier having a particle size of 20 to 100 μm, a ferrite carrier, an iron powder carrier, or a carrier whose surface is overcoated with an appropriate resin is used, and the carrier is a developing roller (32).
The magnetic roller (40) is magnetically held on the outer peripheral portion of the magnetic roller (40).

The toner used has a particle size of 5 to 30 μm and is manufactured by a pulverization method or suspension polymerization method, or a capsule toner. As mentioned above, the first toner hopper (60) contains black toner. The second toner hopper (70) contains color toner (for example, red toner).
is accommodated.

C6 Black Developing Operation The thermal developing operation using black toner in the first toner hopper (60) will be described below.

Note that the developing section (30) is set to the silent image state (Pi) by the switching mechanism (41), and a black mark (see 45X Fig. 4) is displayed on the display section (not shown) of the copying machine main body (1). is displayed, and the developing roller (32) is opposed to the supply roller (63) of the first toner hopper (60).

Also, Table 1. As shown in FIG. 2, the position of the bias changeover switch (SW) is set to l, and the lower frame (3) excluding the upper frame (35) and end member (36b)
A negative bias voltage having the same potential as the developing roller (32) is applied to the end member (6) of the lower frame (36).
A positive bias voltage is applied to 36b).

As shown in FIGS. 17 and 18, the magnetic roller (33) is in a position where its main developing pole (33a) is closest to the photosensitive drum (3) when the solenoid (SL) is off. , and a magnetic pole (33) facing the stirring chamber (38).
b) is located at a position α from the height regulating member (39).

On the other hand, it is assumed that the gap adjustment mechanism (1,00) and the like are set in the following state.

That is, in the gap adjustment mechanism (90), as shown in FIG. 9, a predetermined gap is established between the developing roller (32) and the supply roller (63) by pressure contact between the gap adjustment rollers (91) and (92). is retained.

In the opening/closing mechanism (80), as shown in FIG. 7, the opening/closing cover (82) of the first toner hopper (60)
2), and in the second toner hopper (70), the opening (72) is closed by the opening/closing cover (86). Therefore, color toner does not fall from the second toner hopper (70) in such a state.

In the locking mechanism (100), as shown in FIG. 11, the first toner hopper (60) is locked in a non-removable state, and the second toner hopper (70) is set in a removable state.

In the drive mechanism (120), as shown in FIG. 15, the developing roller drive gear (122) is connected to the first toner hopper (60
), and the rotational force of the photoreceptor drum drive gear (121) is applied to the developing roller drive gear (
122), an idler gear (123), and a supply roller drive gear (124).

In the transmission mechanism (130), as shown in FIG. 19, the clutch (135) has moved to the left in the figure and is in a disengaged state.

In the toner density adjustment means, the developing bias voltage (Vb),
A recovery bias voltage (Vss) is set in each developing state.

When the print switch is turned on with each part of the developing device (5) set as described above, as shown in FIG. ), developing roller (32), =35- The stirring blade (67) rotates, and the supply roller (63) rotates based on the ON operation of the supply roller drive clutch (127).

As a result, in the toner storage tank (66), the stirring blade (6
Based on the rotation of step 7), the black toner is conveyed forward while being mixed and stirred, and at this time, toner blocking and crosslinking phenomena are prevented.

At the outer periphery of the supply roller (63) facing the toner storage tank (66), as shown in FIG. The excess material is scraped off at the tip contact portion of the regulating blade (64).

The toner taken into the minute recesses is removed by the regulation blade (64
), the toner is frictionally charged to a positive polarity by contact with the regulating blade (64), and a thin layer of charged toner is formed on the surface of the supply roller.

On the surface of the developing roller (32), as shown in FIG.
When the carrier is conveyed in a magnetic brush state along the lines of magnetic force generated by the magnet of the magnetic roller (33), and the toner thin layer is conveyed to the opposing portion between the supply roller (63) and the developing roller (32). , on the surface of the developing roller (32) based on the scraping action of the brush-like carrier and the difference between the bias voltages (Vb) and (VS) applied to the developing roller (32) and the supply roller (63). Black toner is supplied.

Here, in the area where the developing roller (32) and the supply roller (63) face each other, not only the above-mentioned toner supply operation but also
In parallel, a collection operation is also performed to collect excess toner from the carrier on the developing roller (32) to the supply roller (63).

The toner supplied to the surface of the developing roller (32) is
As shown in FIG. 1a, the developing roller (32) rotates to transport the developing roller (32) in the direction of the arrow, and first, the two are mixed on the peripheral surface of the developing roller. Next, the developer is transported to the stirring chamber (38), where it is further mixed well with the developer described later while forming a vortex in the direction of the arrow, and is charged to a predetermined value. Toner and carrier are applied to the surface of the developing roller (32) in a predetermined ratio (
The two-component developer mixed to a toner concentration of 6 to 10 wL% is adjusted and set to a developable state.

While the two-component developer consisting of toner and carrier is being adjusted and conveyed on the developing roller (32), the upper frame (35) and the lower frame (36) are temporarily in an electrically 70-ting state. Then, the upper frame (35) and the lower frame (36) are charged by frictional contact with the carrier in the developer, and a positive charge is accumulated.As a result, the outer surface of the developing roller (32) is developed with toner. This phenomenon occurs, causing the developing bias to become ineffective and causing fog on the image. This phenomenon is caused by the upper frame (3
5) and also occurs when a positive voltage is applied to the lower frame (36).

However, in this embodiment, a negative voltage having the same potential as the developing bias of the developing roller (32) is applied to the lower frame (36) excluding the upper frame (35) and the end member (36b), so the toner is The developing roller (32) is maintained in a stable charged state with the carrier, and the outer surface of the developing roller (32) is not developed with toner.

In this state, when the electrostatic latent image formed on the surface of the photoreceptor drum (3) is conveyed to the part facing the developing roller (32), this electrostatic latent image is covered with the two-component developer. It is rubbed and visualized as a black toner image.

The toner that scatters and falls from the developer trying to leave the photoreceptor drum (3) is removed from the lower frame (36).
The tip of the photoreceptor drum (3) side, that is, the end member (36
b), but this end member (36b
) is applied with a positive bias voltage (V t) having the same polarity as the toner, so the toner does not adhere due to electrostatic repulsion.

As shown in FIG. 21a, the developer that has passed through the portion facing the photoreceptor drum (3) is chopped at the portion facing the regulating member (39) and most of it falls into the stirring chamber (38). This fallen developer is mixed with the developer being mixed here while forming a vortex in the direction of the arrow, erasing the toner consumption pattern during development, and furthermore, some of the developer is returned to the developing roller (32). ) is held on the surface of the supply roller (63
), where the toner is supplied again.

The inner surface of the stirring chamber (38) is a smooth curved surface and is formed within the range of the magnetic binding force of the magnetic roller (33), so the developer does not stay in one place.
They are constantly mixed and agitated as the developing roller (32) rotates.

The toner collected by the supply roller (63) is conveyed in the direction of the arrow based on its rotation, passes through the contact portion of the toner outflow prevention film (65), and is collected into the toner supply tank (66).

When the development operation of the electrostatic latent image on the original image is completed in this way, the developing bias voltage (Vb) and/or recovery bias ( Vs) is switched from the developing state to the standby state, some toner is collected from the surface of the developing roller (32) into the toner storage tank (66), and the toner concentration of the developing roller (32) h is 0.1 to 0.1. 2.9
wt%.

D. Development section switching operation Next, from the black development state (Pi) to the color development state (P2
), as shown in Fig. 4, hold the switching lever (42) and rotate the developing section (30) in the direction of the arrow (C''). (not shown) is displayed with a color mark (46).Furthermore, the vibration mechanism (47) and the like described below are operated as follows.

In the vibration mechanism (47) shown in FIG. 6, a vibrator (48),
The tips of (52) sequentially engage with the uneven portions (56) of the frame (57), and the striking portions (5) of each vibrator (48), (52)
0) and (54) are electrically and mechanically attached to the surfaces of the upper frame (35) and lower frame (36) by continuously hitting the upper frame (35) and lower frame (36), respectively. The black toner that is attached will be peeled off.

In the gap adjustment mechanism (90) shown in Figure 9.10, the gap adjustment roller (91) of the developing roller (32)
The supply roller (63) is separated from the gap adjustment roller (92) of the toner hopper (60), and is biased by a spring (98) to move slightly in the direction of the biasing force.

Further, when the developing section (30) is switched to the color developing state (P2), the gap adjustment roller (9) of the developing section (30)
1) is pressed against the gap adjustment roller (93) of the second toner hopper (70), and the gap adjustment roller (93) moves slightly in the direction opposite to the arrow direction against the biasing force of the spring (99). The developing roller (32) and supply roller (7)
3), a predetermined gap is uniformly formed along the axial direction.

In the opening/closing mechanism (80) shown in Fig. 7.8, the developing section (30
), the segment gear (89) moves in the direction of the arrow (C'
) direction, the toner hopper (6
The segment gears (83) and (87) of the first toner hopper (60) rotate in the directions of arrows (d) and (e'), respectively, and the opening (62) of the first toner hopper (60) opens with the opening/closing cover (
82), and the opening (72) of the second toner hopper (70) is opened when the opening/closing cover (86) is retracted therefrom. Therefore, in this state, black toner does not fall from the first toner hopper (60).

In the locking mechanism (100) shown in Fig. 11.12, the release part (101) slips into the opposing surface of the stopper (103) as the developing frame (3) moves, and the other release part (102) Retracted from the opposing surface of the stopper (104), the first toner hopper (60) is set in a removable state, and the second toner hopper (70) is locked in a non-removable state.

In the drive mechanism (120) shown in FIG. 14.15, the developing roller drive gear (122) moves as the developing section (30) moves.
The second toner hopper (70
), and the rotational force of the photoreceptor drum drive gear (121) is transmitted to the developing roller drive gear (125).
122) to the idler gear (125) of the second toner hopper (70) and the supply roller drive gear (126).
It is set to a state where it can be transmitted.

E. Black toner removal operation As described above, the developing section (30) is in the black developing state (Pl)
When the color development state (P2) is detected by the switch (S2), the position of the bias changeover switch (SW) shown in FIG. 2 is set to 3, and the development roller (32) is switched to the color development state (P2).

A positive bias voltage having the same polarity as the toner is applied to the upper frame (35) and the lower frame (36). In addition, as shown in Figs. 17 and 18, a solenoid (S
L) is turned on, and the magnetic pole (33b) of the magnetic roller (33) moves toward the β position, that is, toward the ear height regulating portion (39). Furthermore, the clutch (135) of the transmission mechanism (130) shown in FIG. 19 is engaged.

Then, after a predetermined period of time has elapsed, the main motor (2) is activated, and the photosensitive drum drive gear (121) and the developing roller drive gear (122) of the drive mechanism (120) shown in FIG.
, and the supply roller drive gear (124) start rotating, and the surface of the photoreceptor drum (3) is uniformly charged based on the discharge of the charger (4).

Here, the rotational speed of the developing roller (32) is increased by the speed change mechanism (130) compared to during development, and the circumferential speed ratio of the photosensitive drum (3) and the developing roller (32) is 1: during development.
2, whereas l:2.3. Further, the supply roller drive clutch (not shown) attached to the support shaft (78) of the supply roller (73) of the second toner hopper (70) is turned off, and the supply roller drive gear (126) is turned off. No rotation is transmitted to the supply roller (73).

When switching the black toner remaining in the carrier held on the surface of the developing roller (32) and the developing section (30) from the black developing state (PI) to the color developing state (P2), the vibration mechanism The black toner peeled off from the upper frame (35) and lower frame (36) based on the impact action of (50) is conveyed along the outer periphery of the developing roller (32) based on the rotation of the developing roller (32), and is transferred to the photosensitive drum (3). The developing roller (32) is electrostatically supplied to the surface of the developing roller (32).
Black toner is removed from the outer periphery.

During this black toner removal operation, the upper frame (35
) and the lower frame (36) are formed so that the magnetic brush of the developer on the developing roller (32) is always in contact with these frames (35). ).

This prevents it from scattering and falling toward (36).

In addition, the upper frame (35) and the lower frame (36)
Since a positive bias voltage of the same polarity as the toner is applied, an electrostatic repulsive force acts and the toner adheres to the upper frame (35), lower frame (36), and developing roller (32). There isn't. Even if toner adheres to the upper frame (35) or lower frame (36), the toner is scraped off by the magnetic brush and returned to the developer by the repulsive force. In this way, the black toner adhering to the upper frame (35) or lower frame (36) is supplied to the photosensitive drum (3) together with the toner on the developing roller (32) and is completely removed.

On the other hand, the magnetic pole (33b) of the magnetic roller (33) facing the stirring chamber (38) has moved to the β position and is approaching the ear height regulating portion (39), as shown in FIG.

Therefore, as shown in FIG. 21c, as the black toner removal operation progresses, the toner concentration decreases, and the developer on which the magnetic binding force between the carriers is strongly acting is removed by the brush height regulating member (39
) is dammed up and flows in a swirling manner in the stirring chamber (38), it flows under the strong influence of the magnetic force of the magnetic roller (33), ensuring stirring performance and eliminating residual toner.
Toner removal performance is improved and toner removal operation time is shortened. - The black toner thus supplied to the surface of the photoreceptor drum (3) is conveyed in the direction of arrow (a) based on the rotation of the photoreceptor drum (3) and collected by the cleaning device (7). .

When the black toner removing operation described above is carried out for a predetermined period of time and most of the black toner is removed from the circumferential surface of the developing roller (32), color development becomes possible.

As a result, black toner is not supplied to the electrostatic latent image during color development, and image quality does not deteriorate due to color mixing or the like.

FIG. 20 shows the influence of the speed of the developing roller (32) on the toner removal performance during the above-described toner removing operation. 32), and the amount of developed toner (mg/cm) is plotted on the vertical axis, and the change in the amount of developed toner with respect to the change in toner supply capacity is shown for four cases with different system speeds. According to
It can be seen that this increases in proportion to the circumferential speed ratio of the developing roller (32). Therefore, during toner removal operation, the photoreceptor drum (
3) and the developing roller (32) higher than during development (increased from 2 to 2.3 in this example), the toner removal ability increases and the toner removal operation time is shortened. .

The toner removal operation is performed when the copying machine is powered on, after a power outage or jam removal, and even after the toner hopper is replaced, and toner is removed from the developing section (30). The toner removal operation after the copying machine is powered on is executed during the warming-up time of the fixing device (27), the temperature control time, and the leveling time of the applied oil.

Furthermore, in this embodiment, the removal of the toner on the developing roller (32) was achieved by developing it on the photosensitive drum (3), but the toner was collected via the supply roller (63) to the toner hopper (60) side. It is also possible to do so. That is, in this case, the bias changeover switch (
Set the position of the developing roller (SW) to 2, and
) is applied with a negative developing bias voltage (Vb),
While applying a positive bias voltage to the upper frame (35) and lower frame (36), the supply roller (63)
) is applied to the recovery bias voltage (Vs). As a result, the toner in the developer on the developing roller (32) is
The toner is collected by the supply roller (63) based on the potential difference between the developing bias voltage (Vb) and the collecting bias voltage (Vs) without adhering to the upper frame (35) and lower frame (36).

F. Color development operation With the development device (5) set as described above,
When the print switch (not shown) is turned on, the bias changeover switch (SW) is switched to position l based on a signal from a control device (not shown), and the developing bias (Vb) and collection bias voltage (Vs) are set again. The developing state is set, and the magnetic pole (
33b) returns to the α position, and the clutch (135) of the transmission mechanism (130) is disengaged.

Next, the photosensitive drum (3) rotates in the direction of arrow (a) based on the drive of the main motor (2), and in the developing device (5), the developing roller (32) rotates in the direction of the arrow, and the supply roller is driven. As a result, in the second toner hopper (70), a thin layer of color toner is formed on the outer peripheral surface of the supply roller (73), and a thin layer of color toner is formed on the surface of the developing roller (32). Color toner is supplied, and a two-component developer consisting of carrier and color toner with a predetermined concentration (toner concentration = 6 to 10 wt%) is adjusted on the outer periphery of the developing roller (32).

The surface of the photoreceptor drum (3) is equipped with a charger (
After being charged by the discharge in step 4), an electrostatic latent image is formed based on the image exposure from the optical system (8), and this electrostatic latent image is supplied with color toner at a portion opposite the developing roller (32). The image is visualized as a color toner image.

When the above development operation is completed, in the development device (5), the development bias voltage (vb) and recovery bias voltage (Vs)
is switched to the standby state, and the toner density on the surface of the developing roller (32) is in the standby state (toner density 20, 1 to 2.
Qwt%).

Further, when the developing section (30) is switched from the color development state (P2) to the heat development state (PI), the heat development state (P
1) to the color development state (P2), the upper frame (35) and lower frame (35)
The color toner adhering to 6) is peeled off and the developing section (
When it is detected by the switch (Sl) that the developing roller (30) has been switched to the thermal development state (Pl), the developing roller (32)
starts driving, and the color toner remaining there is supplied to the surface of the photoreceptor drum (3) and sent to the cleaning device (
7), and the state is set such that almost no color toner exists on the outer circumference of the developing roller (32).

Therefore, even if thermal development is performed next time, no color toner will appear on the image.

In addition, as shown in FIG. 16, the cleaning device (7)
The toner collection section (170) includes a toner collection pipe (17).
1) is connected, and its tip is connected to the supply roller (63) or (
The supply roller (63) or (73) is rotatably connected to the toner collection section (170) and the toner collection pipe (171) via a bearing structure (not shown).
) is provided with a conveyance coil (172) having one end fixed to a support shaft (175) of a cleaning device drive gear (174) that meshes with the photoreceptor drum drive gear (121). Further, another conveyance coil (173) is fixed inside the supply roller (63) or (73).

Therefore, the toner collected by the cleaning device (7) is transferred from the toner collecting section (170) to the supply roller (63) or (73) via the toner collecting pipe (171) based on the rotation of the conveying coil (172). transported inside. The toner conveyed to the supply roller (63) or (73) is
Fixed conveyor coil (173) and supply roller (63)
Or, based on the rotation of (73), the supply roller (63) or (73) is gradually stored from -52 to the rear side of the supply roller (63) or (73).

In the above embodiment, the surfaces of the upper frame (35) and the lower frame (36) facing the developing roller (32) are
The magnetic brush of the developer on the developing roller (32) is always in contact with the developing roller (32) not only during development but also when collecting toner.However, during development, the brush is not in contact with the magnetic brush to prevent developer clogging and toner collection. It may also be in contact with the magnetic brush only occasionally.

Further, an alternating current may be superimposed on the direct current voltage applied to the upper frame (35) or the lower frame (36) during toner recovery, similar to the recovery bias voltage.

In the embodiment, the magnetic pole (33b) of the magnetic roller (33)
Although the movement is performed during the toner removal operation before the color change, it may also be performed during the toner density control before and after the development operation. That is, from the state where there is almost no developer on the developing roller (32) before the developing operation to the time when toner is supplied from the supply rollers (63) and (73) and the developer is adjusted to a state ready for development. During the development process, or after the development operation, the toner on the development roller (32) is transferred to the supply roller (6).
3) and (73) to the toner hoppers (60) and (70).
) side, the toner concentration of the developer on the developing roller (32) is low and the agitation performance is poor as described above.
By moving the magnetic pole of the magnetic roller (33), the height regulating part (39)
), the agitation of the developer is ensured.
The rise time will be faster and the recovery efficiency will be improved.

In the embodiment described above, only the rotational speed of the developing roller is increased, but the rotational speed of the photoreceptor drum may also be increased accordingly.

Furthermore, in the above embodiment, the developing device is configured to switch to a toner hopper containing toner of a different color by rotating the single developing roller (32) around the photoreceptor drum (3) with a certain gap. Although the invention is applied, the invention is not limited to this type, and there is also a method in which a plurality of toner supply means containing toners of different colors are arranged around a single fixed developing roller, or As shown in Japanese Patent No. 61-201271, a plurality of toner supply means are arranged around a rotating shaft, and by rotating the rotating shaft, one of the toner supply means is made to face the developing roller. It can also be applied to

(Effects of the Invention) As is clear from the above description, according to the present invention, before selecting the toner supply means and changing the color, when collecting the toner in the developer on the developing roller, the Hodaka When the magnetic pole located upstream of the regulating member in the developer transport direction is moved toward the height regulating member, the developer in the stirring chamber is influenced by the stronger magnetic pole, thereby ensuring the agitation of the developer. improves retrieval efficiency, reduces retrieval time, and
Colors can be changed in a short time.

Therefore, before color change, the toner in the developer is completely removed and collected from the developing roller and stirring chamber, and even if a different color of toner is supplied and development is performed afterwards, the color may become cloudy or the particles may fall off. This has the effect that a beautiful image without any pattern can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing a schematic configuration of a copying machine equipped with a developing device according to the present invention, FIG. 2 is a cross-sectional view of the main part of FIG. 1, FIG. Figure 4 is a perspective view of the switching mechanism, Figure 5 is a sectional view showing the movement of the developing roller, and Figure 6 is a perspective view of the switching mechanism.
7 is a sectional view of the toner hopper, FIG. 8 is a side view of the opening/closing mechanism, FIGS. 9 and 10 are side views of the gap adjustment mechanism, and FIG. 11 is a side view of the locking mechanism. FIG. 12 is a sectional view showing the locked state of the locking mechanism, and FIG.
The figure is a sectional view showing the unlocked state of the locking mechanism.
15 is a side view showing the switching state of the drive mechanism, FIG. 16 is a sectional view of the toner collection mechanism, FIG. 17 is a sectional view showing the moving state of the magnetic roller,
8 is a side view showing the magnetic roller drive device, FIG. 19 is a sectional view of the speed change mechanism, FIG. 20 is a diagram showing changes in the amount of developed toner with respect to changes in toner supply capacity, and FIGS. 21a to 21.
Figure c is a cross-sectional view showing the state of the developer on the developing roller during development, at a low toner concentration (before the brush height regulating section moves), and at a low toner concentration (after the spike height regulating section moves). 3... Photosensitive drum (electrostatic latent image carrier), 5... Developing device, 31... Developing frame, 32... Developing roller, 33... Magnetic roller, 37... Magnetic pole moving mechanism ,3
8... Stirring chamber, 39... Head height regulating member, 41...
Switching mechanism, 60.70... Toner hopper (toner supply means), 63.73... Supply roller (toner supply means)
. Patent applicant: Minolta Camera Co., Ltd. Agent Patent attorney: Mr. Maeda and 2 others (Fig. 17, Fig. 18, Fig. 210, Fig. 21b)? ability to donate

Claims (1)

[Claims] (1) A single developing roller having a plurality of magnetic poles arranged along its inner circumferential surface, a plurality of toner supply means for supplying toner of different colors onto the outer circumferential surface of the developing roller, and a plurality of toner supply means proximate to the developing roller. a brush height regulating member arranged to regulate the conveyance amount of a two-component developer consisting of toner and carrier that is conveyed in a magnetic brush state on the outer circumferential surface of the developing roller; and an upstream side of the spike height regulating member in the developer conveyance direction. a stirring chamber provided in the developing roller, and which enables color change by appropriately selecting the toner supply means, wherein a magnetic pole in the developing roller is formed to be rotatable in a circumferential direction at a predetermined angle; A magnetic pole moving means is provided for moving a magnetic pole located upstream of the brush height regulating member in the developer transport direction toward the brush height regulating member when collecting toner in the developer on the developing roller before color change. A developing device characterized by: