JPH01108575A - Control method for multicolor image forming device - Google Patents

Abstract

PURPOSE:To prevent the color mixing by detecting the movement of a developing part and consuming a toner held on the surface of a developing roll to the surface of an electrostatic latent image carrier. CONSTITUTION:When a developing part 30 is switched from a black developing state P1 to a color developing state P2, a switch S1 is turned OFF, and subsequently, a switch S2 is turned ON. Next, based on an OFF signal, a main motor 2 operates, and a photosensitive drum 3 and a developing roller 32 rotate. Accordingly, a black toner which remains behind in a carrier held on the surface of the developing roller 32 is carried through the outside peripheral part, based on the rotation of the developing roll 32, supplied electrostatically to its surface in an opposed part to the photosensitive drum 3, and the black toner is removed from the outside peripheral part of the developing roller 32. In this case, the black toner is electrified to the plus polarity, repels a developing bias voltage Vb=+50V and transferred positively to the photosensitive drum 3. In such a way, the color mixture is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method of controlling a multicolor image forming apparatus having an electrophotographic copying process.

(Prior Art) Conventionally, as a developing device used in the image forming apparatus,
On the side of the developing roller located on the side of the photoreceptor drum,
A plurality of toner cartridges each having a toner supply/collection roller facing the developing roller are detachably arranged, and toner is selectively supplied from each toner cartridge via the toner supply/collection roller and the developing roller. A method has been proposed by the present applicant in Japanese Patent Application No. 12739/1982, and if this method is used, each toner cartridge contains toner of a different color, and by switching the toner cartridge to be used, Images with desired colors can be obtained.

Further, in the developing device, when the toner cartridge is removed and replaced with one containing toner of a different color, if the toner remains as it is on the surface of the developing roller,
Next, toner of a different color is supplied from the newly installed toner cartridge, causing color mixing in the image, so be sure to collect the toner from the surface of the developing roller into the original toner cartridge after development is complete. There is.

(Problems to be Solved by the Invention) However, since the toner collection operation to the toner cartridge is performed while rotating the toner supply/collection roller, the toner is supplied in parallel with the toner collection. The toner collection efficiency is poor and it takes a long time to completely collect the toner. Further, in the case where a two-component developer consisting of toner and carrier is used, the toner located inside the carrier cannot be completely recovered.

Therefore, by switching the toner cartridge to be used,
When new toner is supplied to the surface of the developing roller, the new toner is mixed with the toner previously held on the surface of the developing roller, resulting in color mixing at the leading edge of the image.

(Means for Solving the Problems) The present invention has been made to solve the problem of color mixing in the multicolor image forming apparatus, and includes a plurality of developer supply means and at least an electrostatic latent image carrier. A rotatable developing roller is provided opposite to the electrostatic latent image carrier, and the developing roller is moved along the outer periphery of the electrostatic latent image carrier, selectively receiving toner supply from the developer supplying means and applying the toner to the electrostatic latent image carrier. In a multicolor image forming apparatus equipped with a developing section that supplies the surface of the latent image carrier, by detecting the movement of the developing section, the toner held on the surface of the developing roller is transferred to the electrostatic latent image carrier. It is consumed on the surface of the surface.

(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 the copying machine, and its structure will be explained along with its operation.

The main body of the copying machine (1) is equipped with an electrostatic capacitor made of a cylindrical body made of aluminum (e.g. 30+++++++) with selenium, zinc oxide, cadmium sulfide, or other organic photoconductors deposited or coated on the surface. A photosensitive drum (3) serving as a latent image carrier is arranged.

The 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 charger (4). charged to a potential.

In the optical system (8), an exposure lamp (9) is turned on, and the light is irradiated onto a document (not shown) placed on a document table (14) that scans in the direction of arrow (b), and the reflected light is The photoreceptor drum (3), which is charged to a predetermined potential as described above, is exposed to light from the exposure point (Xl) through the seven Rufox lens array (12), and the original is placed 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). l l) and the area (X4) via the mirror (13)
The residual charge is removed by irradiation.

B. Structure, etc. of the developing device (5) Next, the structure, etc. of the developing device (5) will be explained with reference to FIGS. 2 to 4.

As shown in FIG. 1.2, the developing device (5) generally includes a first toner hopper (60) that stores black toner, and a second toner hopper (60) that stores color toner other than fish and shellfish (for example, red toner). The toner hopper (70) and a switching mechanism (not shown) move the arrows (c) and (
c') direction and toner hopper (60) or (7).
0) and a developing section (30) that selectively receives toner from the toner and supplies it to the electrostatic latent image formed on the surface of the photoreceptor drum (3).

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

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

The developing roller (32) is made of a conductive non-magnetic material such as aluminum, and minute recesses are formed on the outer peripheral surface by blasting or the like.

Further, inside the developing roller (32), a magnetic roller (3
3) is accommodated, and one end of its spindle is connected to the developing roller (
The other end of the support shaft protrudes from the developing roller (32) and is fixed to the developing frame (31). ) is fixed in a non-rotatable state relative to the

On the other hand, one end of the developing roller (32) has a developing frame (
31), and the other end is rotatably supported by a magnetic roller (31).
3) is rotatably supported on the support shaft.

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).

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.

A stirring chamber (38) is formed along the axial direction on the surface of the lower frame (36) facing the developing roller (32), and the developer flows smoothly through the inner surface of the stirring chamber (38) without stagnation. The counterclockwise side wall of the stirring chamber (38) serves as a regulating portion (39) that faces the developing roller (32) with a predetermined gap therebetween.

Further, a developing section (30) is provided above and below the developing section (30), respectively.
Switches (s l ) and (s 2 ) for detecting are installed, and both are connected to a control device (not shown).

As shown in Fig. 3.4, the developing section (30) having the above configuration is operated by a switching mechanism (not shown) to control the developing roller (32).
) is the supply roller (62) of the first toner hopper (60).
), and a color development state 8 (P2), which faces the supply roller (72) of the second toner hopper (70).

Further, as shown in FIG. 3, the developing section (30), together with the photoconductor drum (3), the charger (4), and the cleaning device (7), is connected to a unit frame ( 15
1) It is designed to be removable.

if, Toner hoppers (60), (70X, see FIG. 2) 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 (
Supply rollers (62) and (72) are arranged in the front openings (61) and (71) of the toner hoppers (60) and (70), respectively, and these rollers are rotatable on the side walls of the toner hoppers (60) and (70), respectively. is supported by Further, the supply roller (62),
(72) is located on an arc (L2X2X fourth light) with its center centered on the photoreceptor drum (3), and the supply roller (
62), (72) and the photosensitive drum (3) are closest to each other, and the distance between them is slightly larger than the outer diameter of the developing roller (32).

The supply rollers (62) and (72) are made of a conductive non-magnetic material such as aluminum, for example, like the developing roller, and minute recesses are formed on the outer periphery by blasting or the like.

Further, regulation blades (64), (74) and toner outflow prevention films (65), (75) are pressed against the rear outer peripheral surfaces of the supply rollers (62), (72), respectively.

Further, the rear portions of the toner hoppers (60) and (70) are arranged such that the supply rollers (62) and (72) and the regulation blade (64)
), (74) and toner outflow prevention film (65), (
toner storage tanks (66) and (76), respectively.
), and a stirring blade (67) is rotatably housed in the toner storage tank (66) of the first toner hopper (60).

Switches (S 3 ) and (S 4 ) are switches for detecting whether or not the toner hoppers (60) and (70) are installed at predetermined positions, respectively, and the signals are outputted to a control device (not shown). It has become.

■, Drive mechanism (120X see Figure 5.6) Drive mechanism (1
20), the photoconductor drum drive gear (121) provided on the support shaft of the photoconductor drum (3) is connected to the main motor (2) (
(see Figure 1), and is connected to the developing roller (32
) The developing roller drive gear (122) attached to the spindle of the developing frame (3) is configured to rotate around the photosensitive drum drive gear (121) while meshing with the photosensitive drum drive gear (121) through the developing frame (3) t. ) and (122) constitute a differential gear device.

Further, the supply roller drive gear (124) is connected to the support shafts of the supply rollers (62) and (72) via a supply roller drive clutch (127) [the clutch corresponding to the supply roller (72) is not shown]. (126) are attached, and these supply roller drive gears (124) and (126) mesh with idler gears (123) and (125), respectively.

Further, although not shown, the stirring blade (67) provided in the first toner hopper (60) is connected to the supply roller drive gear (12).
4) so as to rotate together with the supply roller (62). 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 thermal 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 (62).

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

Therefore, when the main motor (2) is driven in this state and the photosensitive drum drive gear (121) rotates in the direction of the arrow, the developing roller drive gear (122), idler gear (125), and supply roller drive gear are rotated accordingly. (126
) rotate in the directions of the arrows, and the photosensitive drum (3) and the developing roller (32) rotate in the directions of the arrows, respectively. Further, when the supply roller drive clutch (not shown) is turned on, the rotation of the supply roller drive gear (126) is controlled to the supply roller (72).
transmitted to.

iv. 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 (62) and (72)
) is a recovery bias voltage (VS
) is applied, and the bias voltages (Vb), (Vss)
is variable, and by adjusting the voltage value, the toner density on the developing roller (32) can be adjusted.

(2) Developer A two-component developer consisting of toner and carrier is used in the developing device (5) having the above structure.

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 (33) is magnetically held on the outer peripheral portion of the magnetic roller (33). Note that the amount of carrier held on the surface of the developing roller (30) is an amount that can be magnetically restrained and held by the developing roller (30).

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 non-entertainment color toner (for example, red toner).
is accommodated.

C0 black developing operation Below, the silent image operation using black toner in the first toner hopper (60) will be explained according to the time chart of FIG. 7.

When the developing device (5) is in the thermal developing state (Pl) shown in FIG. 2, when the power switch (not shown) is turned on, the switch (Sl) detects the developing section (30) and turns on. , switches (s 3 ), and (s 4 ) detect the toner hoppers (60) and (70), respectively, and turn on. Note that the switch (S2) is off.

When the print switch (not shown) is turned on in this state, the drive mechanism (120) operates the photoreceptor drum (3) and the developing roller (32) based on the drive of the main motor (2).
, the stirring blades (67) rotate, and the supply roller (62) rotates based on the ON operation of the supply roller drive clutch (127).

Further, the developing bias voltage (vb) is set to -150V and the DC bias voltage (Vss) is set to -200V based on a signal from a control device (not shown).

As a result, in the toner storage tank (66), stirring blades = 15
= Black toner is conveyed forward while being mixed and stirred based on the rotation of the root (67), and at this time, toner blocking,
Crosslinking phenomena are prevented.

At the outer periphery of the supply roller (62) facing the toner storage tank (66), the toner sent from the rear is transferred to the supply roller (62).
62) and is conveyed in the direction of the arrow, and 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
), it is frictionally charged to a positive polarity due to contact with the regulating blade (64), and the supply roller (6
A thin layer of charged toner is formed on the surface of 2).

On the surface of the developing roller (32), 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 thin toner layer is transferred to the supply roller (6).
2) and the developing roller (32).
The scraping action of the brush-like carrier and the developing roller (
Black toner is supplied to the surface of the developing roller (32) based on the voltage difference between bias voltages (Vb) and (Vs) applied to the developing roller (32) and the supply roller (62).

Here, in the area where the developing roller (32) and the supply roller (62) 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 (62).

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).
A predetermined ratio of toner and carrier (toner concentration: T r
A two-component developer mixed at a concentration of 6 to 1Qwt%) is prepared 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 development side slides onto 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 retained on the surface of the developing roller (32) again. The toner is transported to the part facing the supply roller (62), where the toner is supplied again.
) has a smooth curved surface, and the magnetic roller (33
), the developer does not stay in one place and is constantly mixed and agitated as the developing roller (32) rotates.

When the developing operation is completed, the charging charger (4) and the exposure lamp (9) are turned off in sequence, and after a predetermined period of time, the developing bias (Vb) is turned off once, and the supply roller (62) is turned off.
), the setting value of the DC bias voltage (Vss) is changed to 1300V.

As a result, the developing roller (3
2) The black toner on the top is electrically drawn to the supply roller (6).
2) and is collected in the toner hopper (60),
The toner density on the developing roller (32) is in the standby state (T2=
O, 1 to 2.0 wt%).

D. In the developing section switching and toner removal operation method, when the changeover switch (not shown) is turned on, the developing section (3o) moves in the direction of arrow (C') by the switching mechanism (not shown), and the black developing state ( PI) to the color development state (P2). At this time, the developing roller (3
2) is an arc (Ll) centered on the photoreceptor drum (3).
) to move along.

As described above, the developing section (3o) is in the silent image state (Pl).
When the color development state (P2) is changed from the state to the color development state (P2), the switch (sl) is turned off, and then the switch (S2) is turned on. Then, the main motor (2) operates based on the off signal of the switch (Sl), and the photosensitive drum (3),
The developing roller (32) rotates.

At this time, the supply roller drive clutch (not shown) of the supply roller (72) is turned off, and the supply roller 19 (72) is stopped.

Also, around the photoreceptor drum (3) there is a charger (
4) is turned on, and the surface of the photosensitive drum (3) is uniformly charged to 1,600 μm. Furthermore, the developing bias voltage (v
b) is set to +50V.

As a result, the black toner remaining in the carrier held on the surface of the developing roller (32) is removed from the developing roller (32).
The black toner is conveyed along its outer circumference based on the rotation of the developing roller (32), and is electrostatically supplied to the surface of the photoreceptor drum (3) at a portion facing the photoreceptor drum (3), thereby removing black toner from the outer circumference of the developing roller (32). At this time, the black toner is positively charged and is positively transferred to the photoreceptor drum (3) by repelling the developing bias voltage (vb=+50V).

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 the black toner is almost completely removed from the circumferential surface of the developing roller (32), color development becomes possible.

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

E. Color development operation With the development device (5) set as described above,
When the print switch (not shown) is turned on, the developing bias voltage (
Vb) is -150V, DC bias voltage (Vss) is -
They are each set to 200v again.

Next, the photoreceptor drum (3) and the developing roller (32) rotate in the direction of the arrow based on the drive of the main motor (2), and the supply roller drive clutch (not shown) is turned on to rotate the supply roller (72). is rotated. 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 (72), and the color toner is supplied to the surface of the developing roller (32). A two-component developer of a predetermined concentration (toner concentration: T1'-6 to 10 w [%) consisting of carrier and color toner is prepared in the outer peripheral portion.

On the other hand, the surface of the photoreceptor drum (3) is connected to the charger (4).
), an electrostatic latent image is formed based on 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). It is visualized as a color toner image.

When the above development operation is completed, in the development device (5), the development bias voltage (vb) and recovery bias voltage (Vs)
is switched, and the toner concentration on the surface of the developing roller (32) is set to a standby state (T2''=0.1 to 2.Qwt%).

Next, when the developing section (30) is switched from the color development state (P2) to the black development state (Pi), although not shown in the time chart, the black development state (Pl) is switched to the color development state (P2). Similar to the operation, the developing section (30
) is switched to the black development state (Pl), the switch (S2) detects that the developing roller (32) starts driving, and the color toner remaining on the surface of the developing roller (32) is transferred to the photosensitive drum (32).
3) and is collected by the cleaning device (7). As a result, a state is set in which almost no color toner exists on the outer peripheral portion of the developing roller (32).

Therefore, even if black development is performed next, color toner will not appear on the image.

Note that black toner is generally used more frequently than color toner. Therefore, if color development is completed and color development is not executed again within a predetermined period of time, the developing section (30) may automatically return to the black development state (Pl).

F. Other Examples In the above example, the developing section (30) is in the black developing state (Pl).
After switching from the state to the color development state (P2) or vice versa, the toner on the development roller (32) is consumed on the surface of the photoreceptor drum (3).

However, when a signal to switch the developing section (30) is input to the control device, the toner on the developing roller (32) is first consumed on the surface of the photoreceptor drum (3), and then the developing section (
30) may be moved.

Also, when switching the developing section (30), the black developing state (
A developing section (30
) may be stopped, and the toner on the developing roller (32) may be consumed in this state.

Further, in the above embodiment, the present invention was applied to a developing device using a two-component developer consisting of toner and carrier, but it is of course applicable to a developing device using a component developer. be.

Furthermore, in the embodiment described above, when removing the toner on the developing roller (30), as in the case of normal image development,
Although the surface of the photoreceptor drum (3) is charged to -600V, the present invention is not limited to this, and the developing bias voltage (vb) may be set to a voltage of the same polarity as the toner (+50V in the above example, but it is not limited to this). voltage) is applied to the developing roller (32).
Alternatively, the toner may be splashed onto the photosensitive drum (3) from the surface of the photosensitive drum (3). If an alternating voltage is superimposed on the developing bias voltage (vb) or the charging potential of the photoreceptor drum (3) is made higher than that during normal development (-600V), the toner removal efficiency can be further improved.

(Effects of the Invention) As is clear from the above explanation, according to the present invention, by detecting the movement of the developing section, the toner remaining on the surface of the developing roller is consumed on the surface of the electrostatic latent image carrier. Even if the developer supply means is switched, toners of different colors are not supplied to the electrostatic latent image carrier at the same time, and a high-quality image without color mixture can be obtained.

Further, the toner held on the developing roller is collected by the developer supply means containing toner of a different color, and different types of toners are not mixed in the developer supply means.

[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 sectional view showing the movement of the developing roller, Figure 5 is an exploded perspective view of the drive mechanism,
FIG. 6 is a side view showing the switching state of the drive mechanism, and FIG. 7 is a time chart showing the control of the copying machine. ■... Copy machine body, 2... Main morph; 3...
・Photosensitive drum (electrostatic latent image carrier), 5...Developing device,
7...Cleaning device, 30...Developing section, 31.
...Developing frame, 32...Developing roller, 33...
Magnetic roller, 35... Upper frame, 36... Lower frame, 60... First toner hopper, 61.71
...Opening portion, 62, 72... Supply roller, 70...
-Second toner hopper, 120...drive mechanism, 121
. . . Photosensitive drum drive gear, 122 . . . Development roller drive gear, 124, 125 . . . Supply roller drive gear,
127...Supply roller drive clutch. Patent Applicant Minolta Camera Co., Ltd. Agent Patent Attorney Aohaku Ao and 2 others

Claims (1)

[Claims] (1) A plurality of developer supply means and a rotatable developing roller facing at least the electrostatic latent image carrier are provided, and the developing roller is moved along the outer periphery of the electrostatic latent image carrier to In a multicolor image forming apparatus comprising a developing section that selectively receives toner supply from a toner supply means and supplies the toner to the surface of the electrostatic latent image carrier, by detecting movement of the developing section, A method for controlling a multicolor image forming apparatus, comprising causing toner held on the surface of the developing roller to be consumed on the surface of the electrostatic latent image carrier.