JPH01108572A - Developing device - Google Patents

Abstract

PURPOSE:To stably control the toner concentration by providing a developing main pole moving means for moving a developing main pole by a prescribed angle in accordance with a toner, when a toner supplying means containing the toner of a different color is selected. CONSTITUTION:A magnetic roll 33 is constituted so as to be turntable around its supporting shaft 34 by an angle theta=5 deg. by a developing main pole moving mechanism 37. That is, for instance, when a toner supplying means containing a black toner is switched to a toner supplying means containing a color toner required for setting high the toner concentration of a developer on a developing roll 32, a developing main pole is moved by a prescribed angle along the carrying direction of the developer from the extreme approach part to an electrostatic latent image carrier. Accordingly, a carrier stuck to the electrostatic latent image carrier together with the toner by a developing operation in the extreme approach part of the electrostatic latent image carrier and the developing roller 32 can be returned into the developer by removing it by the scraping action of a magnetic brush having a strong magnetic restraint in the developing main pole opposed part. In such a way, the supplying and recovering operations of the toner onto the developing roll 32 can be executed smoothly.

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. It is possible to change the color of an image by providing a plurality of toners, each containing toner of a different color, and selecting an appropriate toner supply means.

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 toner in the developer on the developing roller is removed and collected. This 9-time rough toner removal operation is performed by 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.

By the way, color toner and black toner have different amounts of charge, and in order to achieve the brightness unique to colors such as red and blue, it is necessary to make the image density darker than black, so when changing the color from black to color, The color toner density of the developer on the developing roller is set higher than that of black toner.

(Problem to be Solved by the Invention) However, when the toner concentration of the developer on the developing roller becomes high, the carriers in the developer become insufficiently charged and the magnetic binding force between the carriers becomes weaker. At the portion facing the carrier, a phenomenon occurs in which the carrier and toner are attracted to the electrostatic latent image carrier during development.

When such carrier adhesion to the electrostatic latent image carrier occurs,
Transfer failure occurs at the carrier adhesion area, resulting in poor quality images, carrier is wasted, developer is wasted, and toner supply/recovery performance deteriorates.
Toner concentration control becomes unstable. In addition, due to the decrease in the amount of carrier on the developing roller, the ears of the magnetic brush are not sufficiently formed, and a gap is created between the developing roller and the frame that covers it, and toner that has scattered or fallen through this gap adheres to the frame. If the color is changed in this state, the toner mixed with newly supplied toner of a different color may result in a muddy image, or the developer may fall onto the developer on the developing roller due to vibrations, causing a drop pattern. There have been problems such as the resulting image being distorted or falling outside the developing device, which may have an adverse effect.

The present invention has been made in view of the above problems, and provides for stable toner concentration control without adhesion of carrier from the developing roller to the electrostatic latent image carrier, and development with good image quality. The purpose of the present invention is to provide a developing device that can perform the following steps.

(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 for supplying toners of different colors, the color can be changed by appropriately selecting the toner supply means, and the developer magnetic brush made of toner and carrier is formed on the development roller. In a developing device that develops an electrostatic latent image by rubbing it on an electrostatic latent image carrier, the main developing pole in the developing roller facing the electrostatic latent image carrier is formed to be movable in the circumferential direction of the developing port. In addition, when a toner supply means containing toner of a different color is selected, a main developing pole moving means is provided for moving the main developing pole by a predetermined angle according to the toner.

(Function) In the above configuration, when changing the color from black to color, when the main developing pole is rotated by a predetermined angle along the developer conveying direction from the part closest to the electrostatic latent image carrier, the electrostatic latent image carrier The magnetic force is weaker at the closest point to the developer, that is, the developing area, or stronger at the uppermost area of the developing area, which is a predetermined angle away from the developing area. By the way, during color development, the chargeability of color toner is different from that of black toner, and it is necessary to ensure color brightness, so the concentration of color toner on the developing roller is set high.

As a result, the magnetic binding force of the developer carrier above the development port is weakened.

Therefore, in the developing section, during color development, the carrier whose magnetic binding force is weak may separate from the developing roller together with the toner and adhere to the electrostatic latent image carrier, but then at the portion opposite the main developing pole, the magnetic force is strong. The adhering carrier on the electrostatic latent image carrier is scraped off by the magnetic brush and returned to the developer.

Next, when changing the color from color toner to black toner, the main developing pole is returned to the closest point to the electrostatic latent image carrier, and black toner has a higher chargeability than color toner, and brightness is not much of a consideration. Therefore, the black toner density on the developing roller is set lower than that of the color toner. As a result, the magnetic binding force between the developer carriers on the developing roller becomes stronger.

Therefore, during thermal development, the carrier in the developer does not move to the electrostatic latent image carrier together with the toner, and carrier adhesion to the room temperature image carrier does not occur.

(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 of the copying machine (1) is equipped with an electrostatic capacitor made of a cylindrical body (for example, -30 mm) 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.

The light is scanned in the direction of arrow (b) on the document table (14)
The reflected light passes through the seven-lens array (12) and is exposed to the photoreceptor drum (3), which is charged to a predetermined potential, as described above. The photoreceptor drum (3) is exposed to light from point (Xi), and an electrostatic latent image corresponding to the original image is formed on the surface of the photoreceptor drum (3). This electrostatic latent image is supplied with toner at a portion (x2) facing the developing device (5) and is visualized as a toner image. In addition,
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 (Xi) 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.

1. Schematic configuration of developing device (5) U, developing section (30), switching mechanism (41) iv, vibration mechanism (47) v, toner hopper (60X70) vi, opening/closing mechanism (80) V■, gap adjustment mechanism (90) -8=width, lock mechanism (100) ix, drive mechanism (120) x, toner concentration control mechanism xi, developer i, general structure of the developing device (5) The developing device (5) has the following structure. As shown in FIG. 2, a first toner hopper (60) that stores black toner, a second toner hopper (7o) that stores non-color toner (for example, red toner), and a photoreceptor drum (3). ) along the outer circumferential surface I of the photoreceptor drum (3), and selectively receives toner from the toner hopper (60) or (7o) and transfers it to the surface of the photoreceptor drum (3). and a developing section (30) that supplies the electrostatic latent image formed on the image forming apparatus.

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

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.
A conductive, non-magnetic aluminum cylindrical body with micro-recesses (depth 10 to 200 μm) formed on the outer peripheral surface by blasting or the like, or a resin or oxide film formed on the surface of the aluminum cylinder. 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), and (33d) are arranged in the circumferential direction, and one end of the spindle is located inside the developing roller (32). The other end (34) of the support shaft protrudes from the developing roller (32) and the developing frame (31) and is rotatably supported by a bearing recess (not shown) formed in the developing roller (32) and the developing frame (31). 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).

Also, between the developing frames (31), there is an upper frame (31) 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. Then, lower frame (3
A stirring chamber (38) is formed along the axial direction on the surface facing the developing roller (32) of 6), and the inner surface of the stirring chamber (38) is a curved surface that allows the developer to flow smoothly without stagnation. The downstream side wall of the stirring chamber (38) in the developer conveying direction is a regulating portion (39) that faces the developing roller (32) with a predetermined gap therebetween.

The magnetic roller (33) is a developing main pole moving mechanism (37).
As shown in Figures 18a and 18b, -11
= Rotatable around its support shaft (34) by an angle θ-5°. That is, the developing main pole moving mechanism (37) is
As shown in Figures 19a and 19b, the developing frame (
31) Support shaft (34) of magnetic roller (33) protruding from
A lever (37a) fixed to the lever (37a) and a developing frame (34) protruding from the end of the lever (37a) parallel to the support shaft (34)
A positioning pin (37C) passing through the through hole (37b) provided in the unit frame (15
), and a positioning hole (37d) into which the positioning pin (37C) fits.

When the developing frame (31) is in the position shown in FIG. 19a, that is, when the developing roller (32) is in the black developing state (Pi) facing the supply roller (63) of the first toner hopper (60). , the positioning pin (37c) contacts the clockwise end of the positioning hole (37d),
The developing frame (31) rotates counterclockwise to the 19th
When in the position shown in the figure, that is, the developing roller (32)
is formed so as to come into contact with the counterclockwise end of the positioning bin (37c) when it is in the color development state (P2) facing the supply roller (73) of the second toner hopper (70). .

Here, as shown in FIG. 19a, the angle α formed by the arc-shaped positioning hole (37a) is
is smaller than the angle β of rotation between the black development state (Pl) and the color development state (P2). Therefore, the developing frame (31) changes from the black developing state (Pl) to the 198th stage.
When the lever (37
The positioning pin (37c) in a) is the positioning hole (37d)
Since the lever (37a) is restrained from moving in the counterclockwise direction in the figure by coming into contact with the
) rotates counterclockwise around the center. In other words, as shown in FIG. 19b, the spindle (34) of the magnetic roller (33) rotates clockwise by an angle θ.

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).

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.

■, Switching mechanism (41X, see Figure 4.5) Switching mechanism (41
) moves the developing section (30) along the outer peripheral surface of the photoreceptor drum (3), and changes the black 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 (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 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 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 black developing state (PI) to the color developing state (P2) or vice versa, the vibrator ( 48), (52) are repeatedly engaged with and released from the concavo-convex portion (56), and the vibrators (48), (52) vibrate, thereby causing the striking portions (50), (54) to vibrate. The outer parts of the upper 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).
(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 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).

Note that the supply rollers (63) and (73) have an outer diameter of 11.6 mrn, for example, and have a depth of 10 to 2 mm by blasting, etching, or knurling on the outer peripheral surface.
A cylindrical body made of conductive, non-magnetic aluminum or the like is used, which has a 00 μm (1') minute recess formed therein.

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 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.

vi, opening/closing mechanism (see 80X Figure 7.8) opening/closing mechanism (80X)
0) is the opening (6) of the toner hopper (60), (70).
2) and (72) are opened and closed 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.
81X81) and (85X85) are bridged by opening/closing covers (82) and (86), respectively.

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 (3]) of the developing section (30), and this segment gear (89) is connected to the segment gear (83) of the toner hoppers (60) and (70). , (87), and the developing section (
30) in the black development state (PI) or color development state (P2).
), either one of the openings (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 arrow (c) to set the black developing state (PI), ( 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 (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 (see 90X Figure 9.10)
The gap adjustment mechanism (90) adjusts the distance (
gap) 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 gap adjustment rollers (92) at both ends, respectively.
, (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), (97) are formed on the side walls of the toner hopper bodies (61), (71'), and between the stoppers (96), (97) and the support shafts (68), (78). springs (98) and (99) are interposed, and the support shaft (
68) 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.

Shaft, lock mechanism (100
When in the color development state (P2), the first toner hopper (60) is locked, and when it is in the color development state (P2), the second toner hopper (70) is locked.

In this lock mechanism (too), the developing frame (31)
Lock release parts (101) and (102) are provided on the outer surface of the release part (101).
The surface facing the stopper (104)] slopes upward in the direction of the arrow (c), and the surface of the release part (102) [the surface facing the stopper (104)] slopes upward in the direction of the arrow (C'). It is a slope.

On the other hand, as shown in FIG. 12.13, the copying machine main body (1) is provided with stoppers (lO3) and (104) located on the sides of the toner hoppers (60) and (70), respectively. The rear part of the is fixed to the copying machine main body (1) via fixing members (lO5) and (lO6), and a stopper (103),
The free end of (l O4) has retaining holes (107) and (10
8) are formed respectively. Also, toner hopper (60)
, (70) have supply rollers (
63), coaxially with (73), the retaining hole (107),
(108) and an engaging protrusion (l O9) with approximately the same diameter, (110
) 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 black development state (Pi), the release section (
102) slips into the tip of the stopper (104), the engagement hole (108) of the stopper (104) is disengaged from the engagement protrusion (110) of the second toner hopper (70), and the toner hopper (70) is removable (see Figure 13). On the other hand, the stopper (
As shown in FIG. 12, the tip of the toner hopper (103) comes into pressure contact with the side surface of the developing frame (31), the retaining 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), contrary to the above, the release part (101) sinks into the surface facing the stamper (103), and the first toner hopper (60) becomes removable. , the release part (102) is retracted from the part facing the stopper (104) and the second toner hopper (
70) is locked.

That is, when the developing section (30) is in the black developing state (PI), 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 photosensitive drum drive gear (121) provided in 6) is drivingly connected to the main motor (2) (see Figure 1), and the developing roller drive gear (122) attached to the spindle of the developing roller (32). is adapted to rotate around the photoreceptor drum drive gear (121) while meshing with it via the developing frame (31), and these gears (121) 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 (+26) are attached to (78) via a supply roller drive clutch (the clutch corresponding to the 12'7X supply roller (73) is not shown). roller drive gear (124),
(126) meshes 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 (122), 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 (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 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 such a state and the photoconductor drum drive gear (121) rotates in the direction of the arrow, the developing roller drive gear (122), idler gear (125), and supply opening roller drive accordingly. Gear (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 a supply roller drive clutch (not shown) is turned on, rotation of the supply roller drive gear (126) is transmitted to the supply roller (73).

x. Toner density control means (see FIG. 2) Next, the toner density adjustment means supplied to the developing section (30) 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 (Vss) and an AC bias (Vrm
A collection bias voltage (Vs) is applied by connecting the two S) in series, and the bias voltages (Vb) and (Vss) are variable, and by adjusting the voltage value, the developing roller (
32) The toner density above 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 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 other than black (for example, red toner).
is accommodated.

A necessary and sufficient amount of developer is supplied around the developing roller (32) so that it can be restrained by the magnet of the magnetic roller (33) in the developing sleeve (32). That is, the developer around the developing roller (32) is held by the magnetic binding force of the internal magnetic force, and the amount of developer is such that it will not shift or slip even if the developing device is tilted.

Therefore, all the developer around the developing roller (32) is
As the developing roller (32) rotates, it circulates without stagnation. Therefore, during toner recovery, which will be described later, almost all of the toner in the developer is removed and recovered, improving toner recovery efficiency. In addition, the developing section (30) requires
In addition, since only a sufficient amount of developer is present and the amount of developer is set small, toner removal and supply are performed in a short time, reducing toner replacement (color change) time. Moreover, the developing device becomes more compact, and the process unit becomes smaller.

C1 Black Developing Operation The silent image 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 (Pl) 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 main developing pole (33a) of the magnetic roller (33) is shown in FIG. 18a. It is located on the line connecting the spindle (34) of the magnetic roller (33) and the spindle (16) of the photoreceptor drum (3), is closest to the photoreceptor drum (3), and has a gap. It is assumed that the adjustment mechanism (100) and the like are set to the following conditions.

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

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 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. ), the developing roller (32), and the stirring blade (67) rotate, and the supply roller drive clutch (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). , 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 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 of the developing roller (33) 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 and the rotation of the developing roller (32) It 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. Q
wt%.

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 arrow (C'). 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, the vibrator (4'8)
, the tip of (52) is the uneven part (56) of the frame (57)
The striking portions (
50) 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 FIGS. 9 and 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 biasing direction.

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 FIGS. 1I and 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).
In the developing main pole moving mechanism (37) shown in FIGS. 19a and 19b, as the developing frame (31) rotates counterclockwise in the figure from the black developing state (PI),
The lever (37a) moves together with the developing frame (31), and the positioning pin (37c) comes into contact with the positioning hole (37d) just before entering the color development state (P2). Therefore, the lever (37a) rotates counterclockwise around the positioning pin (37c) until it moves to the color developing state (P2). That is, as shown in FIG. 18b, the main developing pole (33a) is shifted by θ-5° in the developer transport direction from the closest point to the photosensitive drum (3).

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 (121)
, the developing roller drive gear (122), =39-, 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 charging charger (4). be done.

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.

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.

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). Note that in order to increase the toner recovery efficiency, a developing bias voltage having the same polarity as that of the toner may be applied to the developing roller (32).

When the black toner removing operation described above continues for a predetermined period of time and almost all of the black toner is removed from the peripheral 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.

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
), 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 consisting of carrier and color toner is adjusted at the outer peripheral portion.

Generally, the amount of charge of color toner is lower than that of black toner, and in order to achieve the brightness unique to colors such as red and blue, it is necessary to make the image density darker than black, so the color toner is adjusted here. The density is higher (8 to 10 wt%) than the black toner density (about 6 wt%) during the thermal development operation.
%) set.

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.

In this case, as the color toner concentration of the developer on the developing roller (32) is high as described above, the carrier in the developer becomes insufficiently charged and the magnetic binding force between the carriers becomes weak. The carrier is attached to the photoreceptor drum (3) at the opposing portion of the photoreceptor drum (3) and the developing roller (32).
).

However, the main developing pole (33a) of the magnetic roller (33)
) is shifted by θ=5° in the developer transport direction from the closest point to the photoconductor drum (3), as shown in FIG. 18b. Even if carrier adhesion occurs at the same time as development is carried out in the θ-5
The adhering carrier is removed by a scraping action by a magnetic brush having a strong magnetic binding force at a position facing the main developing pole (33a) which is separated by .degree.

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 concentration on the surface of the developing roller (32) is in the standby state (toner density: 0.1-2.
0wt%).

Furthermore, when the developing section (30) is switched from the color developing state (P2) to the black developing state (Pi), the black developing state (P
1) to the color development state (P2), the upper frame (35) and lower frame (35)
6) The color toner adhering to the surface is peeled off.

Further, at the time of this switching, the developing frame (31) rotates clockwise from the color developing state (P2) shown in FIG. , and select the development frame (31
) enters the black development state (Pl) shown in FIG. 19b, the positioning pin (37c) comes into contact with the positioning hole (37d). Therefore, thereafter, the lever (37a) rotates clockwise around the positioning pin (37c) until it moves to the silent view=44-image state (Pi).

That is, the magnetic roller (33) rotates clockwise by θ=5° in FIG. 198, and its main developing pole (33a) returns to the closest position as shown in FIG. 18a.

When the switch (Sl) detects that 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 removed. It is supplied to the surface of the photoreceptor drum (3), collected by the cleaning device (7), and then transferred to the developing roller (32).
The state is set such that almost no color toner exists on the outer periphery of the color toner.

Therefore, the next time a silent image is performed, 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 the back side.

In the embodiment described above, switching of the developing section (30) was performed by manually operating the switching lever (42).
As shown in Figure 17, the main body of the copying machine (1)
'(S L) may be provided and the switching lever (42) may be operated by turning it on and off. Note that the switching lever (42) is always biased by a spring (sp) in a direction opposite to the operating direction of the solenoid (SL).

Here, if the solenoid (SL) is turned off after a certain period of time has passed after color toner development, the switching lever (42) will be pulled back by the spring (sp) and the developing section (
30) returns to the thermal development state (Pl).

In this way, by configuring the device to return to a state in which development with black toner is possible after a certain period of time after completion of development with color toner, that is, a state in which it is frequently used, even if color development has been performed previously, However, it is guaranteed that a black copy can be obtained immediately without any color change operation, eliminating the trouble of color change, eliminating copy mistakes, and making copies more efficient.

Further, in the embodiment, the main developing pole moving mechanism (37) is
The mechanism is mechanically linked to the movement of the developing frame (31), but after color change, the magnetic roller (33) is moved by a solenoid, etc.
) may be rotated to move the main developing pole (33a) by -47=.

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, for example, color toner, which requires a high toner concentration of the developer on the developing roller, is supplied from a toner supply means containing black toner. When switching to the stored toner supply means,
By rotating the main developing pole at a predetermined angle along the developer conveyance direction from the part where it approaches the electrostatic latent image carrier, the developing agent is rotated by a predetermined angle along the developer conveyance direction from the part where it approaches the electrostatic latent image carrier, and the toner is absorbed by the developing operation at the part where the electrostatic latent image carrier and the developing roller are closest to each other. The carrier adhering to the electrostatic latent image carrier is removed by the scraping action of a magnetic brush having a strong magnetic binding force at the portion facing the main developing pole and returned to the developer.

Therefore, carrier adhesion to the electrostatic latent image carrier is eliminated, and wastage of carrier is prevented, while one rough operation of supplying toner onto the developing roller is performed smoothly, and toner density control is facilitated. This has the effect that a clear image without color mixture 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 an exploded perspective view of the drive mechanism, FIG. 15 is a side view showing the switching state of the drive mechanism, FIG. 16 is a sectional view of the toner collection mechanism, and FIG. 17 is a perspective view showing another embodiment of the switching mechanism.
Figures 18a and 18b are cross-sectional views showing the states of the magnetic roller during silent imaging and color development, respectively, and Figure 19a
19B are side views of the developing main pole moving mechanism during silent image development and color development, respectively.

Claims (1)

[Claims] (1) A single developing roller having a plurality of magnetic poles arranged along the inner circumferential surface, and a plurality of toner supply means for supplying toner of different colors onto the outer circumferential surface of the developing roller; A developing method that enables color change by appropriately selecting a supply means, and develops an electrostatic latent image by rubbing a magnetic brush of a developer made of toner and carrier formed on a developing roller against an electrostatic latent image carrier. In the apparatus, the main developing pole in the developing roller facing the electrostatic latent image carrier is formed to be movable in the circumferential direction of the developing roller, and when selected as a toner supply means containing toner of a different color, A developing device comprising a main developing pole moving means for moving the main developing pole by a predetermined angle depending on the toner.