JPS61204663A - Developing device - Google Patents

Abstract

PURPOSE:To prevent the amount of a developer from varying owing to the banking of a developer on a scraper by slanting the scraper so that its end part at the side in a developer flowing-out direction form a space almost in a V shape between the scraper and a developer agitator and is positioned nearby a horizontal line extending in the center of the developer agitator. CONSTITUTION:A developer G2 separated from a developing roller 1312 by the 1st slanting part 1392 is guided to the developer agitator 1402 by the 2nd steep slanting part 1392b and the developer G2 separated from the developing roller 1312 is guided smoothly to a developer storage part 1382 without staying on the scraper 1392. Further, the space A is formed, so the agitation time of the developer G2 after use and supplied toner T2 is made long and the gap H is controlled, thereby preventing the toner T2 from scattering when the toner T2 which is not agitated sufficiently is guided out to the developing roller 1312. Consequently, the quantity of the developer is prevented securely from varying owing to the banking of the developer on the scraper and the developer is agitated sufficiently although the constitution is simple.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a developing device installed in an image forming apparatus such as a copying machine.

[Technical background of the invention and its problems]

Normally, in the developing device of an electronic copying machine, the developer that has passed through the developing position is peeled off from the developer conveying means via a scraper and returned to the developer storage section in which the developer agitator is arranged. By stirring the developer with the developer in the container, a good developing state can be maintained at all times.

However, in the conventional Scraper 7, the end of the developer flow direction side is positioned almost directly above the developer agitator so that the peeled developer falls almost directly above the developer agitator. It is in a state.

As a result, the lower surface of the scraper is left wide open, and the developer that has been peeled off from the scraper and guided onto the developer stirring body and the replenished toner come out without being sufficiently stirred, which can cause toner scattering. It had become. In addition, since the slope of the scraper is relatively gentle, for example, as the number of copies is stacked on the carrier, melted toner (spent toner) is formed and the fluidity of the developer decreases. When the developer accumulates on the scraper, the amount of developer changes, and the development state becomes unstable. In particular, the developer agitator scrapes up the developer in the direction opposite to the direction in which the developer flows out of the scraper/mother. However, there is a problem in that the amount of developer that accumulates on the scraper or matrix increases, making it impossible to maintain a good developing operation.

[Purpose of the invention]

The present invention has been made based on the above-mentioned circumstances, and its purpose is to provide a simple structure while reliably preventing changes in the amount of developer due to developer puddle on the scraper. At the same time, it is an object of the present invention to provide a developing device that can sufficiently stir the developer and perform a good developing operation while preventing toner scattering.

[Summary of the invention]

In order to achieve the above-mentioned object, the present invention has an object in which the end of the scraper on the developer outflow direction is located at the center of the developer agitating body in order to form a substantially V-shaped space between the scraper and the developer agitating body. The developer is tilted so that it is located near the horizontal line passing through the scraper 7, and the developer flow is ensured to prevent changes in the amount of developer due to the developer pool on the scraper 7 base, and the developer is sufficiently agitated. The structure is such that it is possible to do so.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is an external perspective view showing a two-color copying machine of a document table moving type as an example of an image forming apparatus to which the developing device of the present invention is applied, and FIG. 2 is a longitudinal sectional front view. That is, 1 is a copying machine main body, and on the upper surface of this copying machine main body 1 is provided a document table 2 that can freely move back and forth in the left-right direction (in the direction of arrow a in the figure). is provided so that it can be opened and closed freely. Also, a paper feed cassette 4 is located on the right side of the main body 1.
However, a paper discharge tray 5 is attached to the left side.

The paper feed cassette 4 is detachably attached to a paper feed section 6 provided on the lower right side of the main body 1. In the paper feed section 6, 7 is a paper feed roller that takes out the paper P1 one by one from the paper feed cassette 4, and 8 is an aligning roller that conveys the paper sent from the paper feed row 27 or the automatic paper feed device I. A detector 9 consisting of a detection lever and a microswitch for detecting paper is provided in front of the aligning roller pair 8.

In addition, the cassette cover (top surface) of the paper feed cassette 4 serves as a paper feed tray 10 that feeds paper either manually (possible when the automatic paper feeder 1 is not installed) or automatically. An automatic paper feeder 1 is provided on this paper feeder 10, and a paper width adjustment guide J2 is provided on the paper feeder 10 on the paper insertion side of this automatic paper feeder 1. It is being

The automatic paper feeder 1 is configured to continuously feed the paper P1 set on the paper feed tray 10 one sheet at a time to the paper feed section 6, and is detachable from the right side of the main body 1. ing.

Further, a photosensitive drum 13 serving as an image carrier is disposed at the center of the main body 1 . Around this photoreceptor drum 13, an exposure optical system 14, a charging device 15.
A two-color developing device 16, a transfer charger 17, a peeling charger 18, a cleaning device 19, a static elimination lamp 20, and the like are arranged in sequence along the rotation direction.

The developing device 16 is divided into two parts, a magnetic brush type first developer and a second developer 16b, each of which is detachable from the main body J.

The first developing device 16a and the second developing device 16b are selectively driven by a reversible motor (not shown) that rotates forward or backward, and this allows the color to be black or one of the other colors. For example, color development such as red, yellow, spine, and green can be selectively performed.

On the other hand, in the lower part of the main body 1, the paper Pl or P2 sent by the pair of aligning rollers 8 is placed on the photosensitive drum 1.
A paper conveyance path 22 is formed which leads to the paper discharge tray 5 through the image transfer section 2 between the image transfer section 3 and the transfer charger 17. The pair of aligning rollers 8 is disposed on the upstream side of the image transfer section 21 of the paper conveyance path 22, and the fixing device 23 and the pair of paper discharge rows 24 are disposed on the downstream side.

Here, the exposure optical system 14 has a reflector 25 at its back.
an exposure lamp 26, mirrors 27 to 30,
and a lens 31 whose position is moved according to the set magnification.

Thus, the photoreceptor P ram 13 is driven by a drive mechanism (not shown) in the direction indicated by the arrow □ in synchronization with the document table 2. First, an image of the original is uniformly charged by the charging device 15 and uniformly irradiated with light by the exposure lamp 26, and an image is formed on the photoreceptor rram 13 by the exposure optical system 14. A latent image is formed. This formed electrostatic latent image is developed by the developing device 16 into a developer image, and is sent to the transfer charger 17 side.

On the other hand, the paper P1 or Pl fed from the paper feed cassette 4 or the automatic paper feeder 1 is fed by the aligning roller pair 8, and the developer image formed on the photoreceptor drum 13 is transferred to the transfer charger 17. Transcribed by. The paper Ps (Pz) to which this developer image has been transferred is peeled off from the photoreceptor drum 13 by a peeling charger J8, passes through a paper transport path 22, and is guided to a fixing device 23, where the transferred image is melted. After being fixed, the paper is ejected to the paper ejection tray 5 by the paper ejection roller pair 24.

On the other hand, after the developer image is transferred onto the paper P1 (Pg), the residual toner remaining on the photoreceptor drum 13 is removed by the cleaning device 1.
9, and an afterimage on the photosensitive drum 13 is erased by a static elimination lamp 20, in preparation for the next copying operation.

In addition, 40 shown in FIG. 2 is a power transformer, 4 is a toner replenishing device for the first developing device, 42 is a toner replenishing device for the second developing device, 43 and 44 are toner concentration detectors, 45 is a paper ejection switch, 46 is a static elimination brush, and 47 is an exhaust fan.

Next, the driving force transmission system will be explained with reference to FIGS. 3 to 5. FIG. 3 is a view of the internal mechanisms of the copying machine main body 1 and the automatic paper feeder 1 viewed from the back side, and FIG. 4 shows the upper unit 50 separated from the lower unit 51 to open the paper conveyance path 22. Indicates the condition. In the figure, 52 is the upper unit
This is a support shaft that pivots □50 and the lower unit 5.

Further, 53 is a drive gear directly connected to the main motor 48, and the driving force of this drive gear 53 is transmitted to the driven gears 54 to 56.
The driving force is transmitted to the drum drive gear 57 via the drum drive gear 57.

Further, as shown in FIG. 5, the driving force of the driving gear 53 is transmitted to the aligning roller driving gear 6 through driven gears 58 to 62.
3, and is further transmitted to the paper feed roller drive gear 65 via the driven gear 64.

Further, as shown in FIG. 5, the driving force of the driving gear 53 is transmitted to the aligning roller driving gear 6 through driven gears 58 to 62.
3, and is further transmitted to the paper feed row 2 drive gear 65 via the driven gear 64.

In this way, the driving force of the driving gear 53 is transferred to the drum driving gear 57.
When transmitting the power to the aligning roller driving gear 63, the drum driving power transmission system 66 and the aligning roller driving power transmission system 67 are separated and transmitted independently, so that the power is transmitted to the aligning roller drive gear 63 independently. The impact caused by load fluctuations before and after the start of the drive of 8 is not directly transmitted to the drum drive gear 57, and image blur caused by the impact can be prevented.

Further, the paper feed roller drive gear 65 is always in mesh with a drive gear 69 that meshes with the driven force transmission gear 68 of the automatic paper feeder 1, and the paper feed roller drive gear 65 is always in mesh with a drive gear 69 that meshes with the driven force transmission gear 68 of the automatic paper feeder 1.
1 is configured to obtain a sufficiently large driving force from the copying machine main body 1 side via a driving force transmission mechanism 70. In addition, compared to a device having its own drive source, it is possible to improve the paper feeding speed, improve the paper separation mechanism, and reduce the size, weight, and cost.

Further, the meshing state between the driven force transmission gear 68 of the automatic paper feeder 1 and the drive gear 69 of the copying machine main body 1 is released when the upper unit 50 is opened as shown in FIG. The power transmission system can be driven by manual operation of the paper device 1, and paper jam removal, maintenance, inspection, etc. can be easily performed.

Further, reference numeral 7 shown in FIGS. 3 and 4 is a scanning motor, and this scanning motor 7 is decelerated by a gear bed and rotates a pulley 72. Here, a wire 74 whose one end is fixed to the tip of the document table 2 and whose other end is supported by a spring (not shown) at the rear end of the document table 2 applies tension to the wire 74 by the idle gorif 5 and the spring 76. pulley 7 via tension pulley 77
It is wrapped around 2.

Therefore, as shown in FIG.
When rotating in the direction (clockwise), the document table 2 moves forward in the C1 direction, and when the magnet 78 attached to the document table 2 is detected by the limit switch 79, the ceiling 2 rotates in the C2 direction, and the document table 2 moves forward in the C1 direction. Move back in the C2 direction.

Further, the scanning motor 7 is synchronized with the main motor 48 by an encoder disk 80 and an encoder sensor 8.

Note that 83 is a magnet attached to the document table 2, 84 is a home switch, and 85 is a paper start switch.

Then, based on the detection signal of the paper start switch 85,
A clutch mechanism (not shown) incorporated in the paper feed row 27 and one roller of the pair of aligning rollers 8 is operated;
Paper feeding and restart are performed at predetermined timing.

In addition, 86 shown in FIGS. 3 and 4 is a developing device motor gear, 87.88 is a driven gear, 89.90 is a developing device drive gear, 91 is a ball discharge roller drive gear, and 92 is an upper heat roller drive. It's a gear. Further, 93 is Heater Ranzo.

In addition, the paper feed section 6 side is pivotally supported via the support shaft 52, and the
The upper unit 5°, which can be rotated by 0°, includes an optical system 14, a charging device 15, an exposure lamp 26, a developing device 16, a cleaning device 19, a static elimination lamp 20, etc., as appropriate around the photoreceptor drum 13. In addition, the document table 2, the paper feed roller 7, the upper roller 8a of the adjusting roller 8, the upper row 223m of the heat roller 23,
and an upper roller 24 & of the paper ejection roller 24 are attached.

The lower unit 5 also includes a paper feed cassette 4, a lower roller 8b of the aligning roller 8, a transfer charger Noah, a peeling charger 18, and a lower roller 23b of the heat roller 23.
, the lower roller 24b of the paper ejection roller 24, the paper ejection tray 5,
A main motor 48 and the like are attached by appropriate means.

After rotating and removing the front cover of the main body 1, almost all of the paper Px is opened via a housing opening/closing support device (not shown).
It is configured so that it can be opened and closed along the paper conveyance path 22 that conveys (Pt).

Furthermore, an operation panel 100 is provided at the upper end of the front side of the main body 1, as shown in FIG.

FIG. 6 shows the operation/main channel 100, including a copy key 101 for executing a copy operation, an interrupt key 02 for specifying an interrupt mode for interrupt copying, setting the number of copies, etc. A numeric keypad 103 for copying colors (for example, black, red).

a color selection key 04 for selecting (blue, green), a color display section 105 for displaying available colors for copying, a paper feed selection key for selecting automatic paper feeding by the paper feed cassette 4 or automatic paper feeding by the automatic paper feeder 11 106. A total counter 1θ7 for counting the total number of copies and a liquid crystal display section 108 are provided.

The liquid crystal display section 108 includes a sheet number display section 09 that displays the number of copies, a status display section 110 that displays various operating states such as paper jam and toner replenishment, a warm-up display section 11, a ready display section 112, and the above-mentioned Color display section-106
A color indicating section 113 that is provided corresponding to the color indicating the selected color 11, a cassette paper feeding mode display section 114 that displays the automatic paper feeding mode by the paper feeding cassette 4, and an automatic paper feeding device I.
It is composed of a paper feeding mode display section 115 for displaying the automatic paper feeding mode according to I, an automatic exposure mode display section 116, and a setting exposure amount display section 117 for manual exposure mode.

It's a moat, automatic exposure key 118 for setting automatic exposure mode,
A manual exposure key 119 for manually setting the exposure amount, a magnification setting key 120 for selecting and setting a specific predetermined copying magnification, and a zoom key 121 for setting an arbitrary copying magnification.
, a magnification display section 122 for displaying the set magnification, etc. are also provided.

Further, as shown in FIG. 7, a second exhaust fan (KITOM 7AN) 124 is disposed at the bottom of the copying machine body 1 to exhaust air toward an exhaust port 123 formed on the bottom of the copying machine body 1. In addition, a filter 225 is provided between the fixing device 23 and the exposure optical system 14.

Further, a restricting means 126 is configured to restrict the heat generated from the heater lamp 93 of the fixing device 23 and the offset prevention silicon vapor applied to the fixing row 223a from going to the exposure optical system 1a side. It has become.

Therefore, even in this copying machine in which the exposure optical system 14 is located near the fixing device 23, heat generated from the fixing device 23 and silicon vapor for preventing offset do not flow into the exposure optical system side 14. Therefore, the mirrors 27 to 30, lens 31, etc. of the exposure optical system 14 are not contaminated with dew or silicone vapor, and it is possible to reliably prevent a defective image in which the copy becomes partially black.

Note that the heat generated from the exposure lamp 26 of the exposure optical system 4 is removed by an exhaust fan 4 disposed at the upper part of the copying machine main body 1.
7, the air is actively exhausted outside the copying machine main body 1 and is not trapped inside the copying machine main body 1.

Next, referring to FIGS. 8 to 25, the developing device 16
The details will be explained below. As shown in detail in FIG. 8, it has a first developing roller 1311 as a first developing body which is a developer conveying means, and a second developing roller 131 as a second developing body which is a developer conveying means. And these developing rollers 1311.131! is selectively driven to produce black color (first ′′
color) or one other color (second color), such as red, yellow, blue, green, etc., can be developed. That is, the developing device 16 includes the first developing roller 1
A first developing device (first developing unit) 16a including 311
and a second developing unit (second developing unit) J6b including a second developing roller 1312. The second developing devices 16a and 16b are both detachable from the main body 1. In this case, the first developing device 16h in the upper stage is configured to be easily attached and detached so that the user can pull it out upward in the figure, and the second developing device 16h in the lower stage is configured to be easily attached and detached.
b is configured to be detachable from the main body 1 when a service person performs maintenance, inspection, etc. The frequently used black toner T is used in the second developing device 16b in the lower stage, and the color toner T1 is used in the first developing device 76m in the upper stage.

The first developing device 16a includes a developing mechanism section J321 and a toner replenishing section 1331 that constitutes the toner replenishing device 41. The developing mechanism section 1321 includes a developing roller 1321 that supplies toner T1 to the photoreceptor drum 13 through an opening 141a1 of a casing 1411, which will be described later.
and a developer magnetic brush J35. formed on the surface of the developing roller 13C. A doctor (regulating member) J371 is provided at the sliding contact portion with the photoreceptor drum 13, that is, upstream of the developing position 1361, that is, on the second developing device 16b side, and regulates the thickness of the developer magnetic brush 1351. 1
361 is also provided on the downstream side, and the developing roller 13110
A scraper serving as a peeling means for scraping off the developer magnetic brush 351 on the surface and guiding it to the developer storage portion 138g;
139t and a developer agitating body 140g housed directly in the developer storage section 138 in the casing 14! It is configured to be housed inside. Note that a developer G weight is provided at a position corresponding to the upper part of the developing roller 13c of the casing 1411.
Toner T1 in developer Gl is detected by magnetically detecting changes in magnetic permeability of (toner TI+ and carrier Ct).
A toner density detector 43 is attached to detect the density of toner.

Further, the developing row 2131% passes through the rotation center of the photoreceptor drum 3 and forms an angle α (approximately 510 degrees) with respect to the horizontal line L1.
A magnetic roll (magnet) 1431 whose center is located on a straight line L2 drawn in a state where It is configured.

The magnetic roll 1431 has five magnetic pole parts J45I to J4.
91, of which the magnetic pole portion 145. ．． 1471゜1
491 is the N pole, magnetic pole parts 1461, 14B, and S are the angle θl between the magnetic pole parts 1451 and 1461.
is approximately 50°, and the angle θ between the magnetic pole part 146 and 1471 is approximately 50°.
2 is approximately 71', the angle θ3 between the magnetic pole portions 1471 and 1481 is approximately 60°, and the angle θ4 between the magnetic pole portions 1481 and 1491 is approximately 60°.

Further, the toner replenishing section 1331 includes a toner replenishing port J5.
0! The developing mechanism section 132! Developer storage section 138! A hopper 1511 facing the hopper 1511, a toner replenishment port 21521 provided in the hopper 15 no.
Hot #151 to convey the toner TI to the 521 side.
A pair of stirring rollers 153 @ for stirring the toner in 1,
1531.

Further, the second developing device 16b is the first developing device 16 described above.
It has almost the same basic configuration as a, and has a toner replenishing section 133 composing the toner replenishing device 42.
1. The shape of the magnetic roll 14 of the developing row 21318
The arrangement structure of the magnetic poles 32 and the mounting position of the toner concentration detector 44 are different. Therefore, other identical components will be designated by reference numerals with the suffix character changed from "1" to "2", and detailed explanations will be omitted. Also, developing roller 13! The magnetic roll 1432 has four magnetic pole parts 145
! ~1482, of which the magnetic pole part 145! ,1
47. is the N pole, and the magnetic pole part 1462. No. 482 is the S pole, and the angle θ5 between the magnetic pole parts J452 and 1462 is approximately 79°, and the angle θ6 between the magnetic pole parts J462 and 1472 is approximately 79°.
is approximately 70°, and the angle θ between the magnetic pole parts 1472 and 1482
The angles are set at approximately 80°. Further, the magnetic roll 1432 is provided such that its center is located on a straight line L3 drawn at an angle β (approximately 1°) with respect to the horizontal line passing through the center of rotation of the photosensitive drum 13.

On the other hand, each of the magnetic rolls 1431. of the first developing device 16a and the second developing device 16b. The developing row 2131 is configured to be able to be rotated to a state where the rotation angle is approximately 30°, and the developing row 2131 is
g, developer magnetic brush 135. on the 13120 surface. ．． 1
It is possible to form 352 or remove 9.

The magnetic rolls 1431 and 1432 of the first developing device 16& and the second developing device 16b are driven by a magnetic roll driving means 160, which will be described later! , 1602 to a predetermined position, the first developing device 16ph or the second developing device 1
6b, one of the developing rollers 1311.131. The developer is applied only to the surface of the magnetic brush 135. ．． 1352 is formed.

That is, when operating the first current device 16 & side,
As shown in FIG. 8, the magnetic roll 1 on the side of the first developer 16&
431 is the magnetic pole part (developing magnetic pole) 1471 is the developing position 13
61, that is, located in the opening 141&1 portion, and in a state in which the doctor 1371 is located approximately midway between the magnetic pole portions 1451 and 1461, and the magnetic roll 143 on the second developing device 16b side! The magnetic pole part (developing magnetic pole) 1472 is inserted into the casing 141 from the opening 1411.
Located on the inner side and magnetic pole part 145! is Doctor J3
72. Then, the first developing device 76a
Developer magnetic brush 135 only on the surface of the side developing roller 13! is starting to form.
1 In addition, when operating the second developing device 16b side, the eighth developing device 16b side is operated.
As shown in the figure, the magnetic roll J43 on the first developing device 16a side
1 by approximately 30 degrees clockwise from the position shown in FIG.
Magnetic roll 143 located inside J1 and on the second current device 16b side! about 3 minutes counterclockwise from the position shown in Figure 8.
Magnetic pole part 147 with 0 degree rotational displacement! is the development position J362
In other words, the opening 147 &! The doctor 1372 is placed in the middle of the magnetic pole portions 1452 and 1462, and the doctor 1372 is placed approximately halfway between the magnetic pole portions 1452 and 1462.

A developer magnetic brush 1352 is formed only on the surface of the developing roller 1322 on the second developing device 16b side.

In addition, the magnetic pole portions 14 of the magnetic rolls 1431 and 14.12
51.145! The doctor 1371. is made of non-magnetic material.
When facing 137m, Development Rosino 3 no 1° 131!
The reason why the developer magnetic brush 1351, 135° is not formed on the surface of the magnetic pole is 145%.

This is because the density of the magnetic brush at 1452 is in a slender state, so the ability to attract the developer G1tG is weak, and therefore it can be easily regulated by the doctors 1311 and 1372, and thereby the sleeve 1441'.

Even if 1442 rotates, the developer GleG1 is a doctor! 37
1.137. Avoid passing through the section.

Next, developing roller zs1! FIG. 10 shows the configuration of the magnetic roll driving means J601 (1602) that rotationally displaces the magnetic roll 1431 (1432) to form or remove the developer magnetic brush 1351 (135,) on the surface of (1sz,). This will be explained with reference to FIGS. 12(a) to 12(b). One end of the shaft 1611 (1e), ) of the magnetic roll 1431 (14s2) is supported via a bearing 163 attached to the frame 162, and a lever 164 is attached to the tip thereof. This lever 16
4 is in a state of being engaged with an engagement groove 167 of an arm 166 rotatably attached via a support shaft 165. Further, a support portion 168 formed at the lower part of the pivot end side of the arm 166 is connected to the granger 1 of the solenoid 169.
Support part 17 connected to 70 and formed at the upper part of the pivot end side
1 is connected to one end of a tension spring 112.

Therefore, when the solenoid 169 is off, the arm 166 is moved to the first position by the biasing force of the tension spring 172.
The magnetic pole part 1451 (1452) is moved to the position indicated by the two-dot chain line in Fig. 1, that is, as shown in Fig. 12(a).
, C137□). Therefore, solenoid 169
When the developing roller 1311 (1312) is turned off, a trap is formed so that the developer magnetic brush 1351 (135,) is not formed on the surface of the developing roller 1311 (1312). Further, when the solenoid 169 is in the ON state, the arm 166 is moved by the tension spring 17.
2, the magnetic pole portion 145.2 is moved to the position shown by the solid line in FIG. (145
2) in a position facing the doctor 1371 (1372)? -164 gold is designed to undergo regenerative displacement. Therefore, when the solenoid 169 is turned on, the developer magnetic brush 7 is on the surface of the developing roller 7311 (J312).
J51 C155t) is formed.

Note that 1552 shown in FIGS. 8 and 9 is a toner residual bone detection device that detects when the amount of toner in the hole 4' 1512 of the second developer 16b is below a predetermined value. Detection lever 1 that rotates according to the amount of toner T2
Permanent magnet 15 attached to actuator 157 integrated with 56
8 is configured to operate when it approaches a reed switch 159 as a detector provided on the outside of the Hora '1.512. Although not shown, E of the first developing device 16a, A151. A remaining toner amount detecting device having the same configuration as the remaining toner detecting device 1552 described above is also provided for the toner remaining amount detecting device.

Further, 180 is a permanent magnet constituting a conveying magnetic force line breaking means 181 disposed near the doctor 137 of the first developing device 16th, and the first developing roller 131! When the developer magnetic brush 1351 is not in operation, the transport magnetic lines of force between the first magnetic pole part 145 and the second magnetic pole part 1461 are destroyed, thereby increasing the efficiency of removing the developer magnetic brush 1351 from the sleeve 1441.

Next, the developing operation of the developing device 16 will be explained. First, when the first developer 16h side is selected to operate using the color selection key, the magnetic rolls 143, . 1432 is the 8th
As the state shown in the figure is reached, the sleeve 1441 of the first developing roller 1311 rotates clockwise in the state shown in FIG. 8, and the sleeve 144! Developer magnetic brush 135□ on the surface of
form. Then, the static image formed in advance on the photosensitive drum 13 is developed with the color developer G1. In this way, when the development of the static latent image is completed, the magnetic roll 143I is About 30 degrees #
Displaced and magnetic pole part 145! is opposed to the doctor 1371, so that the developer magnetic brush 1 is applied onto the sleeve 1641.
New formation of the developer magnetic brush 1351 is stopped, and in this state, the sleeve 1441 is further rotated by a predetermined amount to remove the developer magnetic brush 1351.
is removed. Note that at this time, the second developing roller 1312
Since the developer magnetic brush 1352 is not formed in either of the developer devices 1352, problems such as color mixing will not occur even if either developer 16a or 16b is selected next.

Further, when the second developing device 16b is selected for black color development, the magnetic rolls 1431, 143 . reaches the state shown in FIG. 9, and the sleeve 14 of the second developing roller 131□
42 rotates clockwise in the state shown in FIG. 9, and the surface of the sleeve 1442 forms a developer magnetic brush 135□. After the stationary latent image on the photoreceptor drum 13 is fully black developed in the same manner as described above, the developing operation is completely completed with the developer magnetic plan 135zt removed from the surface of the sleeve 1442.

Next, a total of 8g13 of the transporting magnetic force line breaking means 181 disposed near the doctor 1371 of the first developing device 16&
This will be explained with reference to FIGS.

First, the permanent magnet 1 constituting the transport magnetic field line breaking means 181
80 is thin, with a thickness of about 1 dragon, as shown in Figure 13.
Moreover, the lines of magnetic force run in the thickness direction as shown in FIG. Moreover, the strength of the magnetic force of this permanent magnet 180 is as follows: magnetic pole part 145+ + 146+ + 1481 +
500 Gauss is set larger than 400 Gauss of 149+. In addition, at this time, the developing magnetic pole part 147
1 is set to 1000.

Then, as shown in FIGS. 8 and 9, the permanent magnet 18
The N pole of 0 is the developing roller 13! developer M1361 and doctor 137. It is mounted horizontally to the developing device 16a so as to face the peripheral surface between the developing device 16a.

Therefore, by arranging the permanent magnet 180 as the 2g1 developing unit 16a IC transporting magnetic field line breaking means 181 in this way (therefore, the formation and operation of the developer magnetic plate/1351 on the first developing roller 13) time, i.e. the first
As shown in FIG.
! As described above, the sleeve 144! When the upper developer magnetic plan 1351 is removed, the second
A line of magnetic force is formed between the S pole of the magnetic pole part 1461 and the N pole of the permanent magnet 180, and the conveying magnetic force line a between the second magnetic pole part 1461 and the first magnetic pole part 145 is broken. .

Note that during the developing operation, the lines of magnetic force of the permanent magnet 180 and the second
Because it is directly connected to the magnetic field lines of Tajiku-gun 1461,
The influence of the permanent magnet 180 on the second magnetic pole part 1461 is weak, and the second magnetic pole part 146 and the first magnetic pole part 1451
The transporting magnetic force lines a between the developer Gl and the developer Gl are not destroyed and the transporting operation of the developer Gl is not impaired.

In this way, when the developer magnetic brush 1351 is removed, the Si of the second magnetic pole part 1461 and the permanent magnet 180
A line of magnetic force is formed between the N pole of the second magnetic pole part 146
1 and the first magnetic pole part 145! Since the conveyance magnetic field line a between the carrier C1 and the carrier C1 is broken, the developer G1 will not be taken out even if the fluidity of the developer G or the magnetization characteristics of the carrier C1 changes, and the developer on the sleeve 1441 will not be taken out. The agent can be reduced to almost zero on the magnetic brush Gr'.

Therefore, the adverse effects caused by the first developing device 16b when developing with the second developing device 16b are eliminated, and a high-quality image can be obtained.

Further, as shown in FIG. 16, the first developing roller 131
! The gap d between the sleeve 1441 and the photosensitive drum 13 is the gap d between the sleeve 1441 of the second developing roller 1312
and the photoreceptor drum 13 (d
+>dz) is set.

Further, the sleeve 1441 of the first developing roller 1311 has a surface 144. The developer magnetic brush 1 on the sleeve 144r is machined to have a smooth surface with a width of about 3 μm.
3-51f can be easily removed. Also,
The surface 1442a of the sleeve 1442 of the second developing roller 1312 has a roughness of 10 to 200 μm due to sandblasting, wire plano processing, core processing, etc.
111], and the developer magnetic sill'/
The conveying force of 1352 is increased, and the developing roller 131 of @1 is increased.
The developer magnetic blank 1351, which is composed of 1 and J, can obtain a higher standing state than the developer magnetic blank 1351.

Note that the carrier C in the developer Gl used in the first developer 16h is spherical, and the carrier C2 in the developer G2 used in the second developer 16b is more spherical than that used in the first developer 16a. It is best to have a low degree of opacity or an amorphous shape.

Therefore, the sleeve 144 of the first developing roller 1311
．． Since the surface 144t & of the developer magnetic brush 135I on the sleeve 1441 can be removed well, the electrostatic charge caused by the contact of the developer magnetic brush 1351 with the surface of the photoreceptor drum 13 is reduced. It is possible to prevent leakage of latent images.

Further, even if the developer magnetic pusher 1352 of the second developer 16b is not reliably removed during the developing operation by the first developer 16a and the developer G2 remains on the sleeve 1442, the second developer Since the gap d2 between the first developing device 16b and the photosensitive drum 13 is set wide, the first developing device 16b
The development surface on the photoreceptor drum 13 that has been developed in step m is not contaminated.

Further, while the selected developing device 16a (76b) is operating, the developing bias of the other developing device 516b (16a) is cut, and the developer magnetic nozzle 7zss2 (z3s) of the unused developing device 16b (16*) is cut off. , ) are designed to prevent a decrease in surface potential due to contact with the photoreceptor drum I3 for some reason.

That is, as shown in FIGS. 17(a) and (b),
The first developing roller 1311 is connected to the first contact point 190, and the second developing roller 1312 is connected to the second contact point 191? They are respectively connected to the Gia' depressurizer 192 through them.

Further, the first contact 190 and the second contact 191 are connected to the rotational movement of the magnetic roll 143, (143,) driven by the magnetic roll driving means 1601 (J60.) described above. The configuration is as follows.

That is, as shown in FIGS. 18 and 19, the magnetic roll 143. (J432) and 1611 (161
z) At the other end, there is a magnetic roll 143 made of four composite materials.
1 (1432) is attached to the lever 2Qθ.

This lever 200 has magnetic roll 14 Jl (143
z) is driven by the magnetic roll driving means 1601 (1602). 201a (the state shown in Fig. 18) or the second stock flat part 201b (the state shown in Fig. 19). There is.

Furthermore, a power supply terminal 204 made of a conductive leaf spring connected to the above-mentioned queer asumi pressure 192 via a queer terminal 202 and a cord 203 was disposed on the path of movement of the power supplied part 200b of the Leno p-zoo. The state is 9,
This power supply terminal 204 and the rupture part 20 of the lever 200
0b constitutes the contact 19θ (191).

The power supply terminal 204 is fixed to the developing device frame 205.

Therefore, as shown in FIG. 18, the locking protrusion 200th
First stopper part 201a of ffi stopper member 201
When in contact with (when the developer magnetic brush is not formed),
Contact J 97 (192) is in an open state, and
As shown in FIG. 19, when the second striker is in contact with the groove 201b (when forming the developer magnetic brush), the contact 1
91 (192) is in a closed state.

Then, as shown in FIG. 17(, ), the second developing device 1
6b is selected and the developer magnetic brush 1352 is formed on the surface of the second developing roller 13120, the first contact 190 is open and the second contact 19 is closed.
The state is such that the developing/guineas is applied only to the second developing row 2131□.

Further, as shown in FIG. 17(b), the first developing device 1
6m is selected and the developer magnetic brush 1351 is formed on the surface of the first developing roller 1311, the first contact 190 is closed and the second contact 19 is open.
A developing bias is applied only to the first developing roller 131°.

In this way, while the selected developing device 16m (16b) is operating, the non-image bias of the other developing devices 16b (16a) is cut, and the developer magnetic brush of the unused developing device 16b (16a) is cut. 1352 (7351) is configured to prevent a decrease in surface potential due to contact with the photoreceptor drum 13 for some reason.

Further, as shown in FIGS. 20 and 21, the toner concentration detector 44 of the 8g2 developing device 16a
The detection surface 211a of the head portion 211 is provided to face the central portion of the head portion 402 in the longitudinal direction and to be vertical.

The head portion 112 of the toner concentration detector 44 includes a second
As shown in Figure 2, a coil 21 that generates a magnetic field inside
2.212 is contained inside, and the magnetic permeability changes depending on the mixing ratio of the magnetic carrier C2 and the non-magnetic toner T2 in the developer G2 flowing on the surface of the detection surface 112a. The change in the magnetic field created by the coil is converted into a change in the inductance of the coil, and the concentration of toner T2 in developer G2 is detected.

Then, the -H toner T2k is attached to a conventional glove, and light is irradiated onto it, and the reflected light is used to transfer the toner to the developing side G2.
Compared to a device that detects the toner concentration inside, there is no need for a separate drive mechanism, and the space required for the toner concentration detection device and associated installation can be reduced, and regular maintenance is required to prevent the detection unit from becoming dirty due to toner scattering. It does not require a complete toner concentration detector, and is not affected by one-time changes, making it a stable toner concentration detector.

Note that the toner concentration detector 43 of the first developing device 16a also has a similar configuration. Moreover, as shown in Fig. 23,
The developer stirring body 1402 of the second developing device 16a is moved in a counterclockwise direction (direction of arrow a) opposite to the oral direction of the first sleeve 1442.
It rotates to scrape up the developer G2 from below.

For example, as the number of copies is piled up around the carrier C2, a melt of the toner T2 (smelt toner) is formed, and the flow rate of the developer G2 changes, causing the toner concentration detector 4
Even if the flow of the developer G2 in the placement part 4 becomes poor or the amount of developer G2 accumulates on the scraper/base 139□ and changes slightly, the detection surface of the toner concentration detection 'a44 The entire area 211a is always covered with the developer G2 so that stable toner concentration detection can be performed.

Furthermore, the sensitivity of the toner concentration detector 44 varies depending on the gap H between the detection surface 211a of the toner concentration detector 44 and the developer stirring body 1402, but from the experimental data shown in FIG. It is set to 5 or less in order to maintain stable detection operation.

Note that since the developer G2 is scraped up by the developer agitator 1402 in a corrective manner, the flow of the developer G2 at the detector 44 is not affected by the weight of the developer G2, and a slight change in weight occurs. The control never goes out of order.

Further, as shown in FIG. 25, a scraper 1392 that separates the developer Gz' from the developing roller 1312 is formed in a dogleg shape, and a first inclined portion 1392 that separates the developer G2.
a, and a 21i′lN inclined portion 1392b that has a steeper slope than this and guides the separated developer G2 to the developer stirring body 1402.
It is in a state where it has been formed.

Further, the rear end position of the second inclined portion 1392b is located above the horizontal line a passing through the center of the developer stirring body 1402 and below the line having an angle θ (θ angle 45 degrees) with respect to the horizontal line a. The second inclined portion 1392b and the developer agitator 1
A V-shaped space A is formed between the second inclined portion 1392b and the casing 1.
412 is regulated.

Therefore, the first diagonal part 1392a is
The developer G2 separated from the developer G2 is moved to the developer agitating body 1402 by a second slope portion 1392b having a steeper slope than the second slope portion 1392b.
The developer G2, which is guided by Vc and heated from the developing row 2131□, is smoothly guided to the developer accommodating portion 1382 without being thrown onto the scraper 91392. In addition, by forming the space A, it is possible to lengthen the stirring time between the used in-fill agent G2 and the replenishment waste toner T2, and by regulating the gap H, it is possible to prevent insufficient stirring. This makes it possible to prevent the toner T2 from scattering, which occurs when the toner T2 is led to the developing roller 13I2.

In addition, the Scra 41392 is not limited to the approximately dogleg shape, but the Scra 741 is a flat plate as shown by the two-dot chain line in Fig. 25.
397 has the same effect.

Further, as shown in FIG. 25, a developing row 21312 and a scraper 14139. A gap C of 5 fine roots is formed between the developer magnetic brush 1352 and the outer few developer G2 contributing to development.
The remaining developer G2, which does not contribute to development, is guided to the developer stirring body 1402 separated by 392 and removed by the unseparated magnetic brush 135.
Developing row 2131 as 2'! It is designed so that it can be rotated while remaining on the surface.

When the unseparated magnetic brush 1352' is actively left on the surface of the first developing roller 1312 in this way, the unseparated magnetic brush 1352/ is magnetized as it rotates, and the developer G2 is attracted from the developer storage section 1382. The force (force in the direction shown by arrow A) increases, and the developer G against the developing row 2131□
2 is evenly supplied.

Therefore, since the developer G2 is evenly supplied to the developing roller 1312, it is possible to reliably prevent uneven development due to uneven supply of developer.

Further, the second developing device 16b stores soo, p developer G2 as standard, and the ratio of toner T2 and carrier C2 is toner:carrier=4:10 in weight ratio.
The ratio is 0.

Further, the carrier C2 has a conventional particle size of 74 μm to 1 μm.
50 μm, the surface is not a coarse crystal, but a fine surface crystal, and the ratio of particles with a particle size of 44 μm or less is 1.
Ferrite carrier with a small particle size of 0% by weight or less and peaking at 44 to 105 μm contains nickel, zinc, barium,
Manganese, series) Cz is used.

In addition, FIG. 26 shows the relationship between the number of copies and changes in various items due to the difference in particle size of carrier C2,
It can be seen that by using carrier C2 with a small particle size, the image density and the band bond are stable.

However, if the proportion of the micro carrier C2 (particle size is 44 μm or less) is increased, the absolute value of the amount of charge of the carrier C2 becomes too large, lowering the image density and shortening the life.

Furthermore, as shown in the table below, if the proportion of carrier C2 with a particle size of 44 μm or less is increased, scratches and black spots will occur on the photoreceptor drum 13, which is undesirable, but if the proportion is 10% by weight or less, No black spots were observed even after 40,000 copies were made.Also, the proportion of fine surface crystals with a particle diameter of 44 μm or less was less than 10% by weight, and the peak was 44 to 105 μm. When the above-mentioned ferrite carrier C2 of particle size is used, there are effects such as long life, less toner scattering, and highly dense image quality.
Compared to the standard developer storage of 1500.9 in the developing device 16bVc, the storage of developer G2 is about 1-C300.9 (30
It was confirmed that even if development was performed with the amount reduced (approximately %), there was no change at all, and good development was performed.

Note that the first developing device 16a also uses a carrier C similar to the carrier C2 used in the second developing device 16b.

Similar results were obtained by using

Furthermore, Figure 27 shows the relationship between the number of copies per copy and the change in fog due to the difference in toner particle size. By using all toner TI (T2),
It can be seen that the fogging is reduced.

Therefore, this small particle size toner T+ (Tz) is made of the above-mentioned ferrite having a small particle size in which the ratio of the above-mentioned fine surface crystals with a particle size of 44 μm or less is 10% by weight or less, and the peak is between 44 and 105 μm. By using it in addition to the carrier C+ (Cz), even greater stability of image density can be obtained (see Figure 26).The reason is that the charge of the toner Tl (T2) is If you look at it visually, one grain of toner TI (T2) is gear rear CI (C2).
) by rubbing one crystal on the surface. Therefore, if the surface of carrier C,1 (C2) is fine and uniform, toner Tt
Since the charge imparting area to (Tz) is smaller than that of a carrier with normal surface crystals, toner TI (T2) is charged more uniformly than when using a carrier with normal surface crystals. In addition, the absolute value of the amount of charge becomes smaller. In this way, small particle size toner TI is applied to small particle size carrier C1 (C7).
(T2) If the full amount is used, the amount of charge will be larger than when using normal particle size toner, so blurring and fogging of characters can be prevented, and the amount of charge will be uniform, so the image density will be stable. become. Developer G for 500g
It was confirmed that even when the development was performed with the storage capacity of No. 2 reduced by about 300.9 (about 30 degrees), there was no change at all, and good development was carried out.

Note that similar results were obtained by using the same carrier CI as the carrier C2 used for the second developer 616b in the first developer 16&.

In the above embodiment, a case was explained in which the present invention is applied to a monochromatic color copying machine, but the present invention is not limited to this. The present invention can be applied to any image forming apparatus that forms an image using a developing device.

〔Effect of the invention〕

As explained above, in the present invention, the end of the scraper/moss on the developer outflow direction side forms a part of the approximately V-shaped space between the developer agitator and the developer agitator. The scraper is tilted so that it is located near the horizontal line passing through the center, and the flow is ensured to prevent changes in the amount of developer due to accumulation of developer on the scraper, and at the same time, the agitation of the developer is prevented. one tenth
: It has a configuration that allows for. Therefore, although it has a simple configuration, it reliably prevents changes in the amount of developer due to developer accumulation on the scraper, and allows for sufficient agitation of the developer, resulting in good development operation while preventing toner scattering. This has the advantage of being able to provide a developing device [f' that can perform this.

[Brief explanation of drawings]

FIG. 1 is an external perspective view of an image forming apparatus to which an embodiment of the developing device of the present invention is applied, FIG. 2 is a schematic longitudinal sectional front view, and FIG.
The figure is a view from the rear side of the internal mechanism, Figure 4 is a diagram showing the upper unit in the same open state, Figure 5 is an explanatory diagram schematically showing the entire driving force transmission system, and Figure 6 is an illustration of the operation/maintenance system. Floor plan of flannel,
FIG. 7 is an explanatory diagram schematically showing the exhaust system ttr・℃ in the vicinity of the first processing device, and FIGS. 8 to 25 show the developing device, and FIGS. 8 and 9 show different operating states. FIG. 10 is a partially sectional plan view of the magnetic roll drive means; FIG. 11 is a side view of the magnetic roll drive means;
FIG. 12 is an explanatory diagram showing the operating state of the magnetic roll driving means, FIG. 13 is a perspective view of a magnet used in the conveying magnetic field line breaking means, and FIG. 14 is an explanatory diagram showing the direction of the magnetic field lines of the magnet shown in FIG. 13. FIG. 15 is an explanatory diagram showing the operating state of the conveyance magnetic force line breaking means, and FIG.
Explanatory diagram showing the gap formation state of the second developing roller, No. 17
The figure is an explanatory diagram showing the state of application of the developing bias to the developing roller, FIG. 18 is a front view of the developing/guineas on/off means, FIG. 19 is an explanatory diagram showing the same operating state, and FIG. 20 is the second
FIG. 21 is a schematic longitudinal sectional front view of the developing device; FIG. 22 is a schematic lateral plan view; FIG. 22 is a perspective view of the toner concentration detector;
Figure 3 is a side view showing the installation state of the toner concentration detector.
Figure 4 is an explanatory diagram showing the relationship between toner concentration and detector output;
FIG. 25 is an explanatory diagram showing the shape of the scraper 74 and the state of gap formation with respect to the developing roller. FIG. 26 is an explanatory diagram showing the relationship between the number of copies and changes in various items due to differences in carrier particle size. FIG. 3 is an explanatory diagram showing the relationship between the number of copies and the change in cover due to the difference in toner particle size. 16...Developing device, 131. ...Developer conveying means developing roller, 136. ...Development position, 1382...Developer storage unit, 139□...Scraper (peeling means), 1402...Developer stirring body, G2...Developer. Fig. 10 Figure 12 (a) (b) Figure 16 1441a Figure 17 Figure 18 Figure 19 (Company U) Figure 20 Figure 22 Door 7I Introduction Figure 25 Figure 26 Match (↑) Figure 27 Gohi - Chichinoori (↑ Uncle J Writing on the 1st floor before the procedure 6Q, 4-78 Chief Kiriyoshi Manabu Shiga 1 Incident display special request Numa 60-45295 No. 2, name of the invention development 3, Relationship with the suitability case Patent applicant (3f7'r Co., Ltd. Toshiba 4, agent address: 17 Mori Hill 5, 1-26-5 Toramon, Minato-ku, Tokyo, voluntary amendment C)

Claims (4)

[Claims] (1) A developer conveying means for conveying the developer in the developer storage section to the developing position, and a scraper for peeling off the developer conveyed by the developer conveying means and passed through the developing position from the developer conveying means; In a developing device including a developer agitating body provided in a developer accommodating portion and for agitating the developer, the scraper has an end portion thereof on the developer outflow direction side approximately between the developer agitating body and the developer agitating body. A developing device characterized by being inclined so as to be located near a horizontal line passing through the center of a developer stirring body to form a V-shaped space. (2) The scraper is characterized in that its rear end position is located above a horizontal line passing through the center of the developer stirring body and below a line having an angle of approximately 45 degrees with respect to the horizontal line. Developing device according to item 1. (3) The scraper includes a first inclined portion that separates the developer;
Claim 1, characterized in that it is formed in a substantially dogleg shape having a second inclined part that is steeper than this and guides the separated developer to the developer stirring body. Developing device. (4) The developer agitating body is characterized in that its end on the side in the developer outflow direction rotates in a direction to scrape up the developer into a substantially V-shaped space formed between the developer agitating body and the developer agitating body. A developing device according to claim 1.