JPH01108566A - Developing device - Google Patents

Abstract

PURPOSE:To stabilize the picture quality, and also, to prevent the contact and the damage of both developer supply rolls by providing the developer supply roll so as to be movable forward and backward against the developing roll. CONSTITUTION:On one of a developing roll 32 and developer supply rolls 63, 73, gap adjusting members (gap adjusting rolls) 91-93 are provided, and the developer supply rolls 63, 73 are provided so as to be movable forward and backward against the developing roll 32. Accordingly, when a developing part 30 is switched to a color developing state P2, the gap adjusting roll 91 of the developing part 30 is pressed against the gap adjusting roll 93 of a second toner hopper 70, the gap adjusting roll 93 moves a little in the direction reverse to the direction as indicated with an arrow against the energizing force of a spring 99, and between the developing roll 32 and the supply roll 73, a prescribed gap is formed uniformly along the axial direction. In such a way, the picture quality is stabilized, and the contact and the damage of the roll are prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a developing device used in an image forming apparatus using an electrophotographic copying process, such as a copying machine or a printer.

(Prior Art) Conventionally, the developing device includes a developing section that has a developing roller facing an electrostatic latent image carrier and supplies toner to an electrostatic latent image formed on the surface of the electrostatic latent image carrier. and a developer supply means having a developer supply roller facing the development roller at the opening of a toner hopper detachably provided behind the development section.
This is proposed in the specification of No.-141915.

In this developing device, the toner contained in the hopper is held in a thin layer on the surface of the developer supply roller, and is conveyed to a portion facing the developing roller. The carrier held on the outer periphery of the developing roller is then supplied to the surface of the developing roller based on the scraping action or the like, and a two-component developer consisting of toner and carrier is prepared here. The electrostatic latent image on the surface of the electrostatic latent image carrier is visualized.

(Problems to be Solved by the Invention) However, in the developing device of the above configuration, if the gap between the developing roller and the developer supply roller is not maintained constant, the developer is supplied along the axial direction of the developing roller. This causes unevenness, which causes a problem of unstable image quality. Particularly, as described above, in the case where the toner hopper is removable, there is a risk that the gap may be distorted when the toner hopper is installed, or that the toner supply roller and the developing roller may come into contact and be damaged.

(Means for Solving the Problems) The present invention has been made to solve the above problems, and will be described with reference to the accompanying drawings showing one embodiment.
As shown in the figure, the electrostatic latent image carrier [photoreceptor drum controller (3)
a developing section (30) having a developing roller (32) facing the
A developer supply roller (6) is detachably attached to the rear of the developing section (30) and faces the developing roller (32).
In the developing device (5) equipped with developer supply means [toner hopper] (60), (70) having ), developer supply roller (63), (73)
A gap adjustment member [gap adjustment roller] (91), (92), (93) is provided on one of the developer supply rollers (63).

(73) is provided so as to be movable forward and backward relative to the developing roller (32).

=3- (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 approximately medium flame of the copying machine body (1) is made of an electrostatic latent material, which is made by depositing or coating selenium, zinc oxide, cadmium sulfide, or other organic photoconductors on the surface of a cylindrical body (for example, φ30 mm) made of aluminum. Photosensitive drum (image carrier)
3) is located.

This photoreceptor drum (3) is rotated in the direction of arrow (a) by the drive of the main motor (2) based on 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 the potential of

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 formed 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.

The copy paper (S) is transferred from the paper feed section (20) to the paper feed roller (21).
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.

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) 11. Developing section (30) Ill. Switching mechanism (41) Electric vibration mechanism (47) v. L-ner hopper (60X70) vi Opening/closing mechanism (80) vii. Gap adjustment mechanism (90) Vii,
Outline mechanism (100) ix, drive mechanism (120) x, toner concentration control mechanism xi, developer i, general structure of the developing device (5) , roughly speaking, a first toner hopper (60) that accommodates black toner, a second toner hopper (70) that accommodates color toner (for example, red toner) other than the toner, and an outer peripheral surface of the photoreceptor drum (3). The toner is selectively supplied from the toner hopper (60) or (70) and is transferred to the static plate formed on the surface of the photoreceptor drum (3). and a developing section (30) that supplies the electrostatic latent image.

ii. Image section (30X see Figure 3.4) Development section (30X
), the developing frames (31), (31) (one not shown) are rotatably attached to the rear and front sides of the photosensitive drum support shaft (6).

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 port (32) has an outer diameter of φ16, for example.
An electrically conductive, non-magnetic aluminum cylindrical body having a diameter of xm and having minute recesses (depth 10 to 200 μm shoulder) formed on its outer circumferential surface by blasting or the like, or the surface of an aluminum cylindrical body? A resin or an oxide film is formed to make the material insulating or semi-insulative, or an aluminum cylindrical material whose surface is plasma-polymerized with an organic polymer film by glow discharge in vacuum is used.

A magnetic roller (33) in which a plurality of magnets with magnetic poles extending in the axial direction are arranged in the circumferential direction is housed inside the developing roller (32), and one end of the spindle is attached to the developing roller (32).
The other end (34) of the spindle protrudes from the developing roller (32) and is fixed to the developing frame (31).
(see figure), and is fixed in a non-rotatable state relative to the developing frame (31). On the other hand, the developing roller (3
2) has one end rotatably supported by the developing frame (3), and the other end 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 (33) 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) and (3t), there is an upper frame (3t) that covers the upper and lower parts of the developing roller (32), respectively.
35) and the lower frame (36), and only the portion of the developing roller (32) facing the photosensitive drum (3) and the opposite side thereof are open. The lower frame (36)
A stirring chamber (38) is formed along the axial direction on the surface facing the developing roller (32), and the inner surface of the stirring chamber (38) is a curved surface that allows the developer to flow smoothly without stagnation. The counterclockwise side wall of the stirring chamber (38) has a regulating portion (
39) Toshishita.

Further, a developing section (30) is provided above and below the developing section (30), respectively.
The switches (Sl) and (S2) that detect this are installed.

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).

Further, the developing section (30) is provided with a switching mechanism (41), a vibration mechanism (47), etc., and these will be explained below.

111, Switching mechanism (see 41X Figure 4.5) Switching mechanism (
41) moves the developing section (30) along the outer circumferential surface of the photoreceptor drum (3) and switches between the concrete 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 black developing state (Pl) facing 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 (Co), 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.

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 concrete development or a color development 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 black development state (PI) and the color development state (PI).
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 In addition, the support shaft (I
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 black developing state (Pl) to the color developing state (P2) or vice versa, the vibrator (48) ), (52) repeatedly engage and disengage from the uneven portion (56), causing the vibrators (48), (52) to vibrate, thereby causing the striking portions (50), (54,) to vibrate, respectively. The outer parts of the upper frame (35) and lower frame (36) are struck to give them vibration.

v,) Toner hoppers (60), (70X, see FIG. 7) The toner hoppers (60), (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).
(see Figure 10). Also,
The centers of the supply rollers (63) and (73) are located on an arc (L2) centered on the photoreceptor drum (3),
At the position where the outer peripheral surfaces of the supply rollers (63), (73) and the photoreceptor drum (3) are closest, the gap between them is slightly larger than the outer diameter of the developing roller (32). For example, (63) and (73) have an outer diameter of φ16x.
A cylindrical body made of conductive, non-magnetic aluminum or the like is used, and has micro recesses of 10 to 200 μM in depth formed on its outer peripheral surface by blasting, etching, or knurling.

Openings (62) of toner hopper bodies (61), (71)
, (72) are provided with regulating blades (64), (74) and toner outflow prevention films (65), (75), the tips of which are connected to the rear outer peripheral surface of the 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 toner hoppers (60) and (70) are installed at predetermined positions, respectively, and their signals are output to a control device (not shown). It looks like this.

l Closing mechanism (80
) are the openings (62) of the toner hoppers (60) and (70).
) and (72) to cut off the supply of toner from unused toner hoppers and prevent 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.
1881) and (85X85) have opening/closing covers (82
), (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)]. In addition, the springs CFJ 4) and (8B) are attached to the support shaft (68') and (7B>
One end is locked to the main body (61), (71), and the other end is locked 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) is connected to the segment gear (83) of the toner hopper (60), (70), (87) meshes with the developing section (
30) in the black development state (Pl) or color development state (P2).
), either one of the openings (62) or (72) is opened.

More specifically, the lever (42) of the switching mechanism (4)
When the developing section (30) and the segment gear (89) are rotated in the direction of arrow (c) to set the black developing state (PI) (solid line state in Fig. 8), the segment gear (89)
) as the segment gear (83) moves.

(87) rotate in the directions of arrows (d') and (e), respectively, and as shown in FIG.
The opening/closing cover (82) of o) is retracted to open the opening (62), and the opening (72) of the second toner hopper (70) is opened.
) is closed with an 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 (Co) 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 (6
The opening (62) of the second toner hopper (70) is closed by the opening/closing cover (82), and the opening/closing cover (86) of the second toner hopper (70) is retracted to open the opening (72).

vii. Gap adjustment mechanism (90X, see Figure 9.10) The gap adjustment mechanism (90) adjusts the distance (gap) between the developing roller (32) and the supply rollers (63) and (73) facing it to a predetermined value. This is the value to be set.

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 gap adjustment rollers (92) at both ends, respectively.
, (9'3) 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 (7l) have a slightly larger diameter than the supply roller support shafts (6B) 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 black development state (Pl), the gap adjustment roller (91) is 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.

vii, c7 lock mechanism (see 100X figures 11-13)
The locking mechanism (100) locks the first toner hopper (60) when the developing section (30) is in the black developing state (Pl), and locks the second toner hopper (60) when the developing section (30) is in the color developing state (P2). 70).

In this locking mechanism (100), the developing frame (31)
Lock release parts (101) and (IO2) are provided on the outer surface of the release part (101), and the surface of the release part (101) [the surface facing the stopper (103) described below] slopes upward 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 (+03) and (104) located on the sides of the toner hoppers (60) and (70), respectively, as shown in Fig. 12.13. The rear part of the is fixed to the copying machine main body (1) via fixing members (I05) and (106), and the rear part of the
104) has an engaging hole (I 07), (+08
) are formed respectively. Also, a toner hopper (60),
The main bodies (61) and (71) of (70) have supply rollers (6
3), coaxially with (73), the engagement hole (lO7),
Engagement protrusion (109) with approximately the same diameter as (108), (I]
O) is formed.

In the lock mechanism (+00) having the above configuration, the 11th
As shown in the figure, the developing frame (31
) is set to the black development state (Pl), the release section (
+02) slips into the tip of the stopper (104), the engagement hole (108) of the stopper (+04) is disengaged from the engagement protrusion (+10) of the second toner hopper (70), and the toner hopper (70) is removable (see Figure 13). On the other hand, the stopper (1) of the first toner hopper (60)
As shown in FIG. 12, the tip of the toner hopper (03) comes into pressure contact with the side surface of the developing frame (31), the engagement hole (107) engages with the engagement protrusion (109), 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 (
+04) to the second toner hopper (7).
0) is locked.

That is, when the developing section (30) is in the black developing 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. Conversely, the developing section (30) is in a 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 (120), the support shaft (1
The photoreceptor drum drive gear (121) provided at 6) is drivingly connected to the main motor (2) (see Figure 1), and the developing roller drive gear (+22) attached to the spindle of the developing roller (32). is adapted to rotate around the photoreceptor drum drive gear (121) while meshing with it through the developing frame (31), and these gears (+21) and (12)
2) constitutes a differential gear device.

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), (+
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 (+2
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 (12+) rotates in the direction of the arrow, the developing roller drive gear (I22), idler gear (+23), 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 (63).

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 photoreceptor drum drive gear (12, 1) while meshing with the second toner hopper (70).
The idler gear (125) meshes with the idler gear (125).

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, toner density control means (see Figure 2), then the developing section (
30) The density adjustment means for the toner supplied will be explained.

A developing bias voltage (vb) is applied to the developing roller (32) of the developing section (30), and the supply rollers (63) and (73)
) has a DC bias (V ss) and an AC bias (Vr
A recovery bias voltage (Vs) is applied, in which the bias voltages (V b) and (V ss) are connected in series.
is variable, and by adjusting the voltage value, the toner density on the developing roller (32) can be adjusted.

xi, developer In the developing device (5) having the above configuration, a two-component developer consisting of toner and carrier is used.

As the carrier, a binder type carrier, a ferrite carrier, an iron powder carrier, or a carrier whose surface is overcoated with an appropriate resin is used, and the carrier is used as a developing roller (32).
The magnetic roller (33) is magnetically held on the outer peripheral portion of the magnetic roller (33).

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) other than the toner.
is accommodated.

C1 Black Developing Operation The concrete developing operation using black toner in the first toner hopper (60) will be described below.

The developing section (30) is set to the black developing 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, the developing roller (32) is opposed to the supply roller (63) of the first toner hopper (60), and the gap adjustment mechanism (90) and the like are set as described below.

That is, in the gap adjustment mechanism (90), as shown in FIG.
A predetermined gap is maintained between the two.

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, the color toner will not fall from the second toner hopper (70) in the bent state.

In the locking mechanism (+00), as shown in FIG. 11, the first toner hopper (60) is locked in a non-removable state, and the second toner hopper (7o) 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 toner density adjustment means, the developing bias voltage (Vb),
A recovery bias voltage (V ss ) 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. ), the developing roller (32), and the stirring blade (67) rotate, and the supply roller drive crutch (1
27), the supply roller (63) rotates.

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. and 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). , black is formed 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 fVb) and (Vs) applied to the developing roller (32) and the supply roller (63). 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 conveyed in the direction of the arrow based on the rotation of the developing roller (32).
First, the two are mixed on the circumferential surface of the developing roller. Next, the developer is transported to the stirring chamber (38), where it is further mixed well and charged to a predetermined value, and then moved to the regulating section (39).
The surface of the developing roller (32) that has passed through the opposing part is coated with toner and carrier at a predetermined ratio (toner concentration = 6 to 10w).
The two-component developer mixed with t%) is adjusted and set to a developable state.

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), the two-component developer is applied to this electrostatic latent image. It is rubbed and visualized as a black toner image.

The developer that has passed through the part facing the photoreceptor drum (3) is chopped at the part facing the regulating member (39) and most of it falls into the stirring chamber (38). The developer is mixed with the developer mixed in the direction of the arrow while forming a vortex, erasing the toner consumption pattern during development, and some of the developer is again held on the surface of the developing roller (32) and supplied. It is conveyed to the part facing the roller (63),
At this point, toner is supplied again. In addition, the stirring chamber (38)
The inner surface is a smooth curved surface, and the magnetic roller (33)
Because it is formed within the range where the magnetic binding force of the developing roller (
32) is constantly mixed and stirred.

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 on the developing roller (32) is 0.1. ~2.
It is set to 0wt%.

D. Development section switching operation Next, from the black development state (Pl) 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 (Co). As a result, a color mark (46) is displayed on the display section (not shown) of the copying machine main body (1). Further, the vibration mechanism (47) etc. 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 parts (56) of the frame (57), and the striking parts (5 of each vibrator (4B), (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 has been applied will peel off.

In the gap adjustment mechanism (90) shown in Fig. 9.10, the gap adjustment roller (91) of the developing roller (32) is
The supply roller (63) is biased by a spring (98) and moves slightly in the biasing direction.
) is switched to the color development state (P2), the gap adjustment roller (91) of the developing section (30) 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), and a predetermined gap is created along the axial direction between the developing roller (32) and the supply roller (73). Formed uniformly.

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 (Co).
) direction, the toner hopper (6
0), (70) segment gear (Ill 3), (8
7) Rotate in the directions of arrows (d) and (e'), respectively,
The opening (62) of the first toner hopper (60) is closed by an opening/closing cover (82), and the opening (62) of the first toner hopper (60) is closed by the opening/closing cover (82).
The opening (72) of No. 0) is opened when the opening/closing cover (86) is retracted therefrom. Therefore, in this state, black toner does not fall from the first toner hole 7 ((60)).

In the locking mechanism (100) shown in FIG. 11.12, as the developing frame (31) moves, the release part (101) slips into the opposite surface of the stopper (103), and the other release part (102) (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 state is switched to the color development state (P2) and this is detected by the switch (S2), the main motor (2) is activated after a predetermined time has elapsed, and the photosensitive state of the drive mechanism (120) shown in FIG. 14 is activated. Body drum drive gear (12])
, the developing roller drive gear (122), and the supply roller drive gear (126) start rotating, and the surface of the photoreceptor drum (3) is uniformly charged based on the discharge of the charger (4).

At this time, 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. ) is rotated by the supply roller (73
) will not be transmitted.

Then, 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 The black toner peeled off from the upper frame (35) and lower frame (36) based on the impact action of the mechanism (50) is conveyed along the outer periphery based on the rotation of the developing roller (32), and is transferred to the photosensitive drum (3). ) is electrostatically supplied to the surface of the developing roller (32).
) is removed from the outer periphery. Note that by applying a developing bias voltage having the same polarity as the toner to the developing roller (32), the toner removal efficiency can be further improved.

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.

The above-described toner removal operation is performed when the copying machine is powered on, after power outage or jam removal, and even after toner hopper replacement, and toner is removed from the developing section (30).

Note that the toner removal operation after turning on the power of the copying machine is performed during the warming-up time of the fixing device (27), the temperature control time,
It is carried out during the leveling time of the applied oil.

F. Color development operation With the development device (5) set as described above,
When a print switch (not shown) is turned on, the developing bias (vb) is turned on based on a signal from a control device (not shown).
), the recovery bias voltage (Vs) is again set to the developing state.

Next, the photosensitive drum (3) rotates in the direction of the arrow (a) based on the drive of the main motor (2), and the developing roller (32) in the developing device (5) rotates in the direction of the arrow, and the supply roller is driven. A clutch (not shown) is turned on. 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 the color toner is supplied to the surface of the developing roller (32). A two-component developer of a predetermined concentration (toner concentration, 6 to 10 wt %) consisting of carrier and color toner is adjusted in the outer peripheral area.

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-mentioned development operation is completed, the development bias voltage (Vb) and recovery bias voltage (V s
) is switched to the standby state, and the toner concentration on the surface of the developing roller (32) is in the standby state (toner density = 0.1 to 2).
．． Owt%).

Furthermore, when the developing section (30) is switched from the color developing state (P2) to the black developing state (Pi), the black developing state (
The upper frame (35) and the lower frame (
When the switch (Sl) detects that the color toner adhering to the developing roller (36) has been peeled off and the developing section (30) has been switched to the black developing state (PI), the developing roller (32)
) starts driving, and the remaining color toner is supplied to the surface of the photoreceptor drum (3) and collected by the cleaning device (7), and most of the color toner is present on the outer periphery of the developing roller (32). It is set to not.

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

G. Detachable imaging unit (IU) The imaging unit (IU) is collected when the photoconductor drum (3) reaches a predetermined service life (for example, a predetermined number of copies) or by the cleaning device (7). When a predetermined amount or more of the toner is collected by the cleaning device (7), it is removed from the front side of the copying machine main body (1).

At this time, since the cleaning device (7) is taken out as an imaging unit (IU), there is little risk that the toner collected in the cleaning device (7) will spill and contaminate peripheral devices.

H8 Other Embodiments In the above description, gap adjustment rollers (91) and (92) are provided at both ends of the supporting shaft of the developing roller (32) and the supporting shafts (68), (78) of the supply rollers (63), (73), respectively. ), (93) and press the rollers (g2), (93) against the roller (91) to create a predetermined gap between the developing roller (32) and the supply rollers (63), (73). However, the developing roller (32) and the supply roller (63)
, (73) are members that form a predetermined gap between the gap adjusting rollers (91), (92), and (93).
).

Furthermore, in the above description, the present invention is applied to a developing device that uses a two-component developer consisting of toner and a carrier, but the present invention is not limited to this, and can also be applied to a developing device that uses a l-component developer. Of course it can be done.

(Effects of the Invention) As is clear from the above description, according to the present invention, a predetermined gap is always formed between the developing roller and the developer supplying roller opposing the developing roller. On the surface, the developer is not partially compressed, aggregated, or solidified, and a developer layer of uniform thickness is formed, which stabilizes the image quality and prevents contact and damage between the rollers. .

[Brief explanation of the drawing]

Figure 1 is a sectional view showing the general structure of the copying machine, and Figure 2 is a cross-sectional view showing the schematic configuration of the copying machine.
3 is a sectional view showing the structure of the developing section,
Fig. 4 is a perspective view of the switching mechanism, Fig. 5 is a sectional view showing the movement of the developing roller, Fig. 6 is a sectional view of the vibration mechanism, Fig. 7 is a sectional view of the toner hopper, and Fig. 8 is a side view of the opening/closing mechanism. Figure, No. 9
, FIG. 10 is a side view of the gap adjustment mechanism, FIG. 11 is a side view of the locking mechanism, FIG. 12 is a sectional view showing the locking mechanism in the locked state, and FIG. 13 is a sectional view showing the locking mechanism in the unlocked state. Figure 14 is an exploded perspective view of the drive mechanism;
The figure is a side view showing the switching state of the drive mechanism. DESCRIPTION OF SYMBOLS 1... Copying machine main body, 2... Main motor, 2... Photosensitive drum (electrostatic latent image carrier), 5... Developing device, 7...
-Cleaning device, 30... Developing section, 3I... Developing frame, 32... Developing roller, 33... Magnetic roller, 35... Upper frame, 36... Lower frame, 41... Switching mechanism, 42... switching lever, 47
... Vibration mechanism, 48 ... Vibrator, 60 ... First toner hopper, 61 ... Main body, 63 ... Supply roller, 70 ... Second toner hopper, 73 ... Supply roller , 80... opening/closing mechanism, 81... frame, 82...
・Opening/closing cover, 83, 87.89 ・Segment gear, 90 ・Gap adjustment mechanism, 91°92.93・
...Gap adjustment roller, 100...Lock mechanism, +0
1... Lock release part, 103, 104... Stopper, 107, 108... Engagement hole, 109, 110...
Engaging protrusion, 120... Drive mechanism, 12.1... Photosensitive drum drive gear, 122... Developing roller drive gear, 12
4.125... Supply roller drive gear, 127... Supply port, -ra drive clutch. Patent Applicant Minolta Camera Co., Ltd. Agent Patent Attorney Aohaku Ao and 2 others

Claims (1)

[Claims] (1) A developing section having a developing roller facing the electrostatic latent image carrier, and a developer supply means detachably mounted behind the developing section and having a developer supplying roller facing the developing roller. A developing device comprising: a gap adjustment member provided on at least one of the developing roller and the developer supply roller, and the developer supply roller is provided so as to be movable forward and backward with respect to the development roller. .