JPS61204645A - Developer - Google Patents

Abstract

PURPOSE:To reduce scattering of toner and to obtain fine picture quality by using specific carriers for a two-component developer consisting of toner and carriers. CONSTITUTION:Carriers of small particle size which are fine surface crystal and consist of <=10wt% of carriers of <=44mum in particle size so that their peak size is 44-105mum are used for the two-component developer consisting of toner and carriers. The carriers use ferrite carriers (nickel, zinc, barium, or manganese) of small particle size and image density and the quantity of electrostatic charging become stable because of the use of the carriers of small particle size. There is not any change at all even when development is carried out while the storage amount of a developer G2 is about 300g less than the standard storage amount of the developer, i.e. 500g in the 2nd developing device 16b, so that the development is carried out excellently. Consequently, the life is prolonged, a toner scatter is reduced, and fine and high picture quality is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a developer that can be applied to, for example, a developing device of a copying machine, and more particularly to a two-component developer consisting of toner and carrier.

[Technical background of the invention and its problems]

Developing devices such as copying machines usually use a two-component developer consisting of toner and carrier.

However, in the conventional developer of this kind, a carrier having a particle size of 74 to 150 .mu.m and a rough crystal surface has been used. Therefore, there are serious problems in that the toner is not uniformly charged, the toner tends to scatter, and the image density becomes unstable.

On the other hand, when the proportion of minute carriers is increased, the amount of charge of the carriers increases, the image density decreases, and the life span is shortened. Further, there is a problem in that black spots occur due to scratches on the photoreceptor drum.

[Purpose of the invention]

The present invention has been made based on the above-mentioned circumstances, and its objectives are to provide a long service life, less toner scattering, and high-density image quality, while reducing the amount of developer stored to the standard developer storage amount. On the other hand, it is an object of the present invention to provide a developer that can perform good development without any change even if development is performed in a state where the amount has been reduced to some extent.

[Summary of the invention]

In order to achieve the above object, the present invention provides a two-component developer comprising a toner and a carrier, as the carrier:
A small particle size carrier is used in which the proportion of fine surface crystals having a particle size of 44 μm or less is 10% by weight or less, and the peak size is 44 to 105 μm.

[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 with a moving document table as an example of an image forming apparatus to which a developing device using the developer of the present invention is applied, and FIG. 2 is a longitudinal sectional front view.

That is, reference numeral I denotes a copying machine main body, and a document table 2 is provided on the top surface of this copying machine main body 2, which can freely reciprocate 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. Further, a paper feed cassette 4 is attached to the right side of the main body I, and a paper discharge tray 5 is attached to the left side.

The four paper feed cassettes mentioned above are removably attached to the paper feed section 6 provided on the lower right side of the main body 1. In the paper feed section 6, one sheet of paper P1 is fed from the double paper feed cassette 4.
The paper feed roller 8, which takes out sheets one by one, is a pair of aligning rollers that conveys the paper fed from the paper feed roller 7 or the automatic paper feeder 11, and the alignment roller f a-5 pair 8
A detector 9 consisting of a detection lever and a microswitch for detecting paper is provided in front of the paper.

In addition, the cassette cover (top surface) of the paper feed cassette 4 serves as a paper feed tray 1o for manually feeding paper (possible when the automatic paper feeder 1 is not installed) or automatically feeding paper as appropriate. An automatic paper feeder 11 is provided on the paper feeder 10, and a paper width adjustment guide Z2 is provided on the paper feeder IO on the paper insertion side of the automatic paper feeder II.

The automatic paper feeder 11 is a device that continuously feeds the paper P 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 Z3 serving as an image carrier is disposed approximately at the center of the main body I. Around this photoreceptor drum I3, an exposure optical system I4 and a charging device 15 are provided.
．． A two-color developing device 16, a transfer charger I2, a peeling charger 18, a cleaning device 19, a static elimination lamp 20, and the like are arranged in sequence along the rotation direction.

Further, the developing device 16 is divided into two parts, a magnetic brush type first developer z6a and a second developer 1fib, each of which is detachable from the main body l.

Then, the first developing device 16a, the second developing device 16b,
A reversible motor (not shown) rotates forward or backward to selectively drive one of the two, thereby selectively developing black or other colors such as red, yellow, blue, and green. It is possible to do it.

On the other hand, in the lower part of the main body 1, the paper P1 or P2 sent by the pair of aligning rollers 8 is placed on the photosensitive drum 1.
A paper transport path 22 is formed which leads to the paper discharge tray 5 via the image transfer section 21 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 transfer section 21 of the paper transport path 22, and the fixing device 23 and the pair of paper discharge rollers 24 are disposed on the downstream side.

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

Thus, the photosensitive drum 13 is driven by a drive mechanism (not shown) in the direction indicated by the arrow in the drawing in synchronization with the document table 2.

First, an image of a document that is uniformly charged by the charging device 15 and uniformly irradiated with light by the exposure wrap 26 is formed on the photoreceptor drum 13 by the exposure optical system 14, and an electrostatic latent image is formed. It is formed. This formed electrostatic latent image is developed into a developer image by the developing device 16, and transferred to the transfer charger Z.
Sent to the 7th side.

On the other hand, the paper P or P fed from the paper feed cassette 4 or the automatic paper feed device 11 is fed by the pair of aligning rollers 8, and the developer image formed on the photoreceptor drum I3 is transferred to the transfer charger. Transcribed by I7. The paper P, (P, ) to which this developer image has been transferred is peeled off from the photosensitive drum 13 by the peeling charger 18, and the paper is transported "1".
1 The sheet passes through the feeding path 22 and is guided to the fixing device 23, where the transferred image is melted and fixed, and then discharged to the sheet discharge tray 5 by the pair of sheet discharge rollers 241C.

On the other hand, after the developer image is transferred onto the paper P, (P,), the residual toner remaining on the photosensitive drum 13 is removed by a cleaning device 19.
The residual image on the photosensitive drum I3 is erased by the static eliminating lamp 20, and the photosensitive drum I3 is prepared for the next copying operation.

In addition, 40 ke 11! shown in Figure 2! 41 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 discharge switch, 46 is a static elimination brush, and 47 is an exhaust fan. be.

Next, the driving force transmission system will be explained with reference to FIGS. 3 to 5. FIG. 3 is a nine-dimensional view of the internal mechanisms of the copying machine main body I and the automatic paper feeder 11 seen from the back side, and FIG. Indicates the state of In the figure, 52#-4 is a support shaft that pivots the upper unit 50 and the lower unit 51.

Further, 53 is a driving gear directly connected to the main motor 48, and the driving force of this driving gear 53 is transmitted to the driven gears 54 to 56.
K so as to transmit the driving force to the drum drive gear 57 via
It has become.

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.
3VC is transmitted, and further transmitted to the paper feed roller 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. Impacts due to load fluctuations before and after the start of driving of the drum H are not directly transmitted to the drum drive gear 57, and image blur due to 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 feed bag t11, and the automatic paper feed device 1 of the automatic separation type
1 is configured to obtain a sufficiently large driving force from the copying machine main body l 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 11 and the driving wJ gear 69 on the copying machine main body 1 side is released when the upper unit is opened 5 degrees as shown in FIG. The power transmission system can be driven by manual operation of the paper feeding device 11, and paper jam removal, maintenance, inspection, etc. can be easily performed.

Further, 71 shown in FIGS. 3 and 4 is a scanning motor, and this scanning motor 71 is decelerated by a gear head and rotates the pulley 22. Here, tension is applied to the wire 24 by an idle pulley 75 and a spring 76, which have one end fixed to the tip of the document table 2 and the other end supported by a spring (not shown) at the rear end of the document table 2. Pulley 2 is connected via the tension boob 977.
It is wrapped around 2.

Therefore, as shown in FIG.
When the document table 2 rotates in the direction (clockwise), the document table 2 moves forward in the direction a, and when the magnet 78 attached to the document table 2 is detected by the limit switch 79, the pulley 72 rotates in the direction C2, and the document table 2 moves backward in the C2 direction.

Further, the scanning motor 71 is synchronized with the main motor 48 by an encoder disk 80 and an encoder sensor 81.

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 roller 7 and one roller of the pair of aligning rollers 8 is operated;
K to feed and restart paper at the specified timing.
It has become.

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 drive gear for the normal discharge roller, and 92 is a body for the upper heat roller. It is a moving gear. Further, 93 is a heater lamp.

In addition, the paper feed section 6 side is pivotally supported via the support shaft 52, and the
The upper unit 50, which can be rotated by 0 degrees, includes an optical system 14, a charging device 15, an exposure lamp 26, a developing device I6, a cleaning device 19, a static eliminating lamp 20, etc. around the photosensitive drum 13. Furthermore, the document table 2, the paper feed roller 2, the upper roller 8m of the aligning a-ra 8, the upper roller 23a of the heat roller 23, and the upper roller 23a of the heat roller 23.
1 and an upper roller 24m of the paper ejection roller 24 are attached.

The lower unit 5IVc also includes a paper feed cassette 4, a lower side a-ra 8b of the aligning roller 8, a transfer charger 17,
Peeling charger 18, lower roller 23 of heat roller 23
b1 Lower roller 24b1 of paper ejection a-ra 24, paper ejection tray 5, main motor 48, etc. are attached by appropriate means.

After rotating and removing the fan cover of the main body 1, the paper P,
It is configured so that it can be opened and closed along the paper conveyance path 22 that conveys (P,).

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 panel 100, which includes a copy key 101 for executing a copy operation, an interrupt key 102 for specifying an interrupt mode for interrupt copying, setting the number of copies, etc. numeric keypad 103, copy color (for example, black, red).

A color selection key 104 for selecting a color (blue, green), a color display section ZO5 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 172 A key 106, a total counter 107 for counting the total number of copies, and a liquid crystal display section 108 are provided.

The liquid crystal display section 10B includes a number display section 109 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 111, a ready display section 112, and the color display section. 105, a color indicating section 113 that indicates the selected color, 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 mode using the automatic paper feeding device II. Bypass paper feeding mode display section 115, automatic exposure mode display section 116,
It consists of a set exposure amount display section 117 in manual exposure mode.

Also, an automatic exposure key 118 for setting an automatic exposure mode;
A manual exposure key 119 for manually setting the exposure amount, a magnification setting key 1201 for selecting and setting a specific predetermined copying magnification, and a zoom key 1 for setting an arbitrary copying magnification.
21. Magnification display section 122 that displays the set magnification
etc. are also provided.

Further, as shown in FIG. 7, a second exhaust fan 124 is disposed at the bottom of the copying machine main body I to exhaust air toward an exhaust port 123 formed on the bottom of the copying machine main body 1. At the same time, a filter 125 is provided between the fixing device 23 and the exposure optical system 14. Then, a restricting means Z26 is configured to restrict the heat generated from the heater lamp 93 of the fixing device t23 and the offset prevention silicon vapor coated with the fixing cola 23a K from going to the exposure optical system 14 side. ing.

Even in this copying machine in which the exposure optical system z4 is located near the fixing device 23, heat generated from the fixing device 23 and silicon vapor for preventing offset 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 hazel lamp 26 of the exposure optical system 14 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, there are a first developing roller ZJZ as a first developing body which is a developer conveying means, and a second developing roller ZJZ as a second developing body which is a developer and conveying means. Z31. These developing rollers 131, . 131. is selectively driven to perform color development of black (first color) or one color other than black (second color), such as red, yellow, blue, and green. That is, there are 16 developing devices, a first developing device (first developing unit) 16 including a first developing roller 1311;
a and 1@2 developing roller 131. A second developing device (
The first and second developing units 16a and IRb are both detachably attached to the main body 1. In this case, the first developing device 16a 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 16a in the lower stage is configured to be easily detachable.
6b is configured so that it can be attached to and detached from the main body I when a service person performs maintenance, inspection, etc. Black toner T2, which is frequently used, is stored in the second developing device 1 in the lower stage.
6b, and the color toner T1 is used in the first developing device 1 in the upper stage.
K is designed to be used at 6m.

The first developing device 16a includes a developing mechanism portion 132° and a toner replenishing portion Z33. which constitutes the toner replenishing device 41.
It is composed of. The developing mechanism section 132. is a developing roller 13 that supplies toner T to the photosensitive drum 13 through an opening 141am of a casing 14z1, which will be described later.
2. And this developing roller Z 31. The sliding contact portion of the developer magnetic brush 135m formed on the surface of the photoreceptor drum 13, that is, the development position 136. The developer magnetic brush 13 is provided on the upstream side of the developer magnetic brush 13
5. a doctor (regulating member) 137 for regulating the thickness of the
Development position Z36. The developing roller 131. A scraper 1391 serving as a stripping means for removing the developer magnetic brush z351 on the surface of the casing 141. It is configured to be housed inside. Incidentally, in a position corresponding to the upper part of the developing roller 1311 of the casing 141, the developer G1 (toner TI+ and the carrier C1) is placed in a position corresponding to the upper part of the developing roller 1311 by magnetically detecting the change in magnetic permeability of the developer G1 (toner TI+ and carrier C1). A toner density detector 43 is attached to detect the density of toner.

Further, the developing roller 1311 passes through the rotation center of the photoreceptor drum 13 and forms an angle α (approximately 51°) with respect to the horizontal line L1.
A straight line drawn to a state where .

A magnetic roll (magnet) I431 provided with its center located above, and this magnetic roll 143. A sleeve (carrying body) 144 that is fitted onto the outside and rotates clockwise in the figure.
It is composed of.

The magnetic roll 143I has five magnetic pole parts 145. ~14
9I, of which magnetic pole portions 1458, 147 . .

I49. N pole, magnetic pole part 1415. ,14g, is S
The angle θ between the magnetic pole parts 145I and 1461, 'H approximately so', mmmx6+ and 147+ and t
The angle θ between D is approximately 71°, and the magnetic pole portions Z471 and 148.
The angle θ between the magnetic pole portion 148. and 149
1 and the angle θ4 is set to about 60', respectively.

Further, the toner supply section 133. is toner supply port 15
0I to the developing mechanism section 132. A hopper 1511 facing the developer storage section 138 and a developer replenishing port 150 within the hopper 1511. Toner replenishment a-ra 152. , and this toner supply roller 1
Hopper 151m with 52 side to convey toner TI.
A pair of stirring rollers l for stirring the toner inside 53. ,
153. It has a configuration with.

Further, the second developing device 16b has almost the same basic configuration as the first developing device 1sa described above, and the toner replenishing section 133.
Hopper 151. Shape and development of a-ra 131. Magnetic a-le I43. The arrangement structure of the magnetic poles and the mounting position of the toner concentration detector 44 are different. Therefore, other identical components will be designated by symbols with the suffix character changed from "," to rtjI/c, and detailed explanations will be omitted. Also, a developing roller 131□0m roll 1432 and four magnetic pole parts 145. ~Z48. , of which F
a Magnetic pole part 45. , I 47. is N pole, magnetic pole part 14
6. , 1411° is the S pole, and the ra pole part 145
．． and 146. The angle θS between the magnetic pole part 14 is approximately 79°,
6. The angle θ6 between and 147° is approximately 70°, and the magnetic pole part I
41! and 1482, respectively, are set to about 80'. In addition, magnetic roll I43. is provided such that its center is located on a straight line L3 that passes through the center of rotation of the photoreceptor drum 13 and is drawn at an angle β (approximately 1°) with respect to the horizontal line.

On the other hand, the WJ1 developer 16a and the second developer 16b
Each magnetic a-le 1438.143! The developing rollers 131 . ．． Developer magnetic brush 1 on the surface of 131t
35. ．． 1352 can be formed or removed.

Then, the first developing device 16a and the second developing device 16b
magnetic roll 143. ．． 143! is switched to a predetermined position by magnetic roll driving means rso, xso, IiC, which will be described later, so that the developing σ-ra 1 of either the first developing device 16m or the second developing device 11b is
31. , 131. Developer only on the surface of magnetic blank 135
．． ．． 135. is starting to form.

That is, when operating the first developing device 16a side, as shown in FIG. 8, the magnetic roll 143. The magnetic pole part (developing magnetic pole) 1471 is at the developing position 1.
36. in a state facing the opening 141□, and in a state facing the magnetic pole portion 145. and 1461, and move the magnetic roll I432 on the second developing device 16b side to the magnetic pole part (
Fa electrode for development) 747. is the opening 141. , located inside the casing 1412 and the magnetic pole portion 145. so that it faces the doctor 137t. The developing roller 131 on the side of the first developing device 16a. The developer is applied only to the surface of the magnetic brush 135. is starting to form.

In addition, when operating the second developing device Ifib side,
As shown in FIG. 8, the magnetic roll 143 on the side of the busy first developing device 16a. is rotated approximately 30 degrees clockwise from the position shown in FIG. The magnetic pole portion I47° is located inside the casing I411 through the opening 141a, and the second developing device 16
b side magnetic roll 143. Rotate about 30 degrees counterclockwise from the position shown in FIG. 8 to remove the magnetic pole part I47. is in a state facing the development position 136, that is, located in the opening 141a, and the magnetic pole portion I45! The torque controller 1372 is positioned approximately midway between the angles 146 and 146 degrees. The developer magnetic brush 135° is formed only on the surface of the developing roller 131t of the W2 developing device 76b@J.

Note that the magnetic roll 143. ．． 143! magnetic pole part 145,
．． 145. Doctors 137, . . . are made of non-magnetic material. 13
7. When facing the developing roller I 31. .

The reason why the developer magnetic brush 1358, 135° is not formed on the surface of the magnetic pole part 145. .

At 1452, the density of the magnetic brush is in a slender state, so the ability to attract the developer G, G2 is weak, and therefore the doctor 137. , 137. This is because the sleeve 144. .

Even if 144 rotates, the developer G, , G, remains in the doctor 137
,．． 137. Avoid passing through the section.

Next, a magnetic roll drive means 160, ( 16 o, )
The structure of the magnetic roll 143° (z4s,)O axis zsB(zsz,)t)) will be explained with reference to FIGS. 10 to 12 (a) (bl).
It is supported via a bearing 163 attached to the
A lever 164 is attached to its tip. The tip of the lever 164 is engaged with an engagement groove 167 of an arm 166 rotatably mounted via a support shaft 165. Furthermore, the arm 166
A support part 16tt formed at the lower part of the pivot end side is connected to the plunger 170 of the solenoid 169, and one end of h112 is connected to a support part 171 formed at the upper part of the pivot end side.

When the solenoid 169 is off and in the 9 state, the arm 166 is moved to the position shown by the two-dot chain line in FIG.
Draw the magnetic pole part 145° (145,) as shown by l
37. The lever 164 is placed in a position opposite to (137,).
It is designed to hold. Therefore, when the solenoid 169 is off, the developing roller 137. (131,
) is provided with a developer magnetic brush 135. (1352) is not formed. Also, solenoid 16
9 is in the ON state, the arm 166 resists the biasing force of the tension spring 172 and moves to the position shown by the solid line in FIG. 11, that is, the magnetic pole part z4s, (xs, The lever 164 is rotated to a position where it faces the doctor 137. (137,).Therefore, when the solenoid I69 is turned on, the developing low-yrsr is turned on.

(1312') has a developer magnetic blank 135° (
135z) is formed.

Note that I55. shown in FIGS. 8 and 9. hopper 151 of the second developing device 16b. Toner T inside.

This is a toner remaining amount detection device that detects when the amount of toner has fallen below a predetermined value, and a permanent magnet 158 attached to a detection lever 156 that rotates depending on the amount of toner T and an integrated actuator 157 K is attached to the hopper. 151! As a detector provided on the outside of the sensor, it is configured to operate when it is close to the glued switch 159. Although not shown, the hopper 161 of the first developing device 16m. A remaining toner amount detecting device having a configuration similar to the above-mentioned remaining toner amount detecting device 1155* is also provided.

Further, 180 is a doctor 137I of the first developing device 16a.
It is a permanent magnet constituting the transport magnetic force line breaking means 181 arranged near the first magnetic pole part 145° and the second magnetic pole part 146t when the first developing roller 1311 is not in operation.
The developer magnetic brush 135
The structure is such that the removal efficiency from the pickpockets 1441 of m is increased.

Next, the developing operation of the developing device Z6 will be explained. First, when the first developer 16a side is selected to operate using the color selection key, the magnetic σ-rules 143, . 143. is the 8th
When the state shown in the figure is reached, the first developing roller 131. Sleeve 144. rotates clockwise in the state shown in FIG. 8, and developer magnetic brush 135. is applied to the surface of sleeve 144I.
form. Then, the electrostatic latent image previously formed on the photoreceptor drum I3 is developed with the color developer G1. In this manner, when the development of the electrostatic latent image is completed, the magnetic roll 143° is rotated by about 30°, and the magnetic pole portion I45. is opposed to the doctor 137I, so that the developer magnetic brush 135□ is applied onto the sleeve l641.
The new formation of the sleeve 14 is stopped, and in this state, the sleeve 14 is further formed.
4. rotates a predetermined amount and the developer magnetic brush Z35. is removed. In addition, at this time, the second development a-rough J1. The developer magnetic brush 1352 is not formed in either of the developer devices 16m and 76b, so that problems such as color mixing will not occur even if either developer 16m or 76b is selected next.

Further, when the second developing device 16b is selected for black color development, the magnetic σ-rule 143. , 143 degrees become the state shown in FIG. 9, and the second developing roller 1 j 1. Sleeve 144. rotates clockwise in the state shown in FIG. 9, and the sleeve 144. Developer magnetic brush Z35 on the surface!
form. After the electrostatic latent image on the photoreceptor drum I3 is developed to black in the same manner as described above, the sleeve 144 is
．． developer from the surface of the magnetic brush 135. The developing operation ends with the removed.

Next, the configuration of the conveying magnetic field line breaking means 181 disposed near the doctor 1371 of the first developing unit 16m is changed to the first developing unit 16m.
This will be explained with reference to FIGS. 3 to 15.

First, the permanent magnet 180 constituting the conveying magnetic field line breaking means 181 is as thin as about la+ as shown in FIG. 13, and its magnetic field lines run in the thickness direction as shown in FIG. 14. Furthermore, the strength of the magnetic force of this permanent magnet 180 is the same as that of the conveying magnetic pole portion 145. , 146. ,14g,,1
49. It is set at 500 Gauss, which is larger than the 400 Gauss of the previous model. In addition, at this time, the developing magnetic pole part 147
．． is set to 1000 Gauss.

Then, as shown in FIGS. 8 and 9, the permanent magnet 18
The N pole of 0 is the developing position 1361 of the developing roller 131 and the doctor 137. Developing unit 16m facing the curved area between
Install horizontally against the

By arranging the permanent magnet 180 as the first developing device 16a K transporting magnetic force line breaking means 181 in this way, the developer magnetic brush 135. During the non-forming operation of the doctor I37., that is, as shown in FIG.
Opposed to the developer magnetic brush 135 . on the sleeve 1441 as described above. When I tried to remove the 21st
i1 pole part 146. Lines of magnetic force are formed between the S pole of the permanent magnet 180 and the N pole of the permanent magnet 180, and the second magnetic pole part 1461 and the first magnetic pole part 145. The transporting magnetic field lines a between the two are in a broken state.

Note that during the developing operation, the lines of magnetic force of the permanent magnet 1110 and the lines of magnetic force of the second magnetic pole part 1461 are perpendicular to each other, so that the lines of magnetic force of the second magnetic pole part 146. Permanent magnet 180
has a weak influence, and does not destroy the transport magnetic force lines a between the second magnetic pole part 1461 and the first magnetic pole part 1451, thereby impairing the transport operation of the developer G1.

In this way, the developer magnetic brush 135. When the second magnetic pole portion 146. is removed, the second magnetic pole portion 146. S pole and permanent magnet 180
A line of magnetic force is formed between the N pole of the second magnetic pole part Z4
6. Since the conveying magnetic force line a between the first magnetic pole portion 145° and the first magnetic pole portion 145° is broken, the developer G can be taken out even if the fluidity of the developer G or the magnetization characteristics of the carrier C1 change. Therefore, the developer magnetic brush G1 on the sleeve 144I can be reduced to almost zero.

For this reason, when developing with the second developing unit 16b, the first
There is no need for alignment using the developing device 16b, and high quality images can be obtained.

Further, as shown in FIG. 16, the first developing roller 131
．． Sleeve 144. The gap d1 between the second developing roller 131! and the photosensitive drum 13 is the second developing roller 131! Sleeve Z44.
and the photoreceptor drum 13 ((d
,>d,) is set.

Further, the sleeve 1441 of the first developing roller 1311 has a surface 1441. The developer magnetic brush 1 on the sleeve 144+ is machined to have a smooth surface with a roughness of about 3 μm.
35. It is arranged in such a way that it can be easily removed. Also, the sleeve 144 of the second developing roller Z s 1°. The roughness of the surface 144ta is 10 to 200 by sandblasting, wire brushing, knurling, etc.
The developer magnetic brush 135 is processed to have a rough surface of μm.
．． by increasing the conveying force of the first developing roller Z31. A higher accumulated state of developer can be obtained than that of the developer magnetic brush 1351 formed by the developer magnetic brush 1351.

Note that the carrier C0 in the developer G1 used in the first developing device 16a is spherical, and the carrier C1 in the developer G used in the second developing device 16b is more spherical than that used in the first developing device 16a. Low-grade or amorphous conflict is best.

Therefore, the first developing roller 131. sleeve 144
Sleeve 144.m is smoothed by smoothing surface 144)B of sleeve 144.
Current detergent magnetic brush 135. Since the developer magnetic brush 135□ can be removed satisfactorily, leakage of the electrostatic latent image due to contact of the developer magnetic brush 135□ with the surface of the photoreceptor drum 13 can be prevented.

Further, during the developing operation by the first developing device I6a, the developer magnetic brush 135 of the second developing device 16b! Even if the developer G remains on the sleeve 144 and is in good condition, the gap d between the second developer 16b and the photoreceptor drum 13 is set wide. The developing surface on the photosensitive drum 13 that has been developed by the first developing device 11ia is not contaminated.

Further, while the selected developing device 16a (16b') is operating, the developing bias of the other developing devices 16b (1f; a) is cut, and the developing device 1f; b is not used.
(16a) Developer magnetic bra // 13 f (13
J) is designed to prevent a decrease in surface potential due to contact with the photoreceptor drum 13IfC for some reason.

That is, Fig. 17+8), (as shown in bl,
First developing roller 131. is through the first contact 190,
Maku, the second current great roller 131! are each connected to a bias voltage 192 via a second contact 191.

Also, the first contact 190 and the second contact! 91
is a magnetic roll Z431O4, ? driven by the aforementioned magnetic roll drive means 160m (160,). , ) is configured to be switched in conjunction with the rotational movement of.

That is, as shown in FIGS. 18 and 19, the axis 161° (16x,) of the magnetic roll I431 (143,)
At the other end, there is a magnetic roll 1431 (made of conductive material).
1432) is attached.

This lever 200 has a magnetic roll of 143° (14J
, ) are driven by the magnetic roll driving means zso, (xso, ), and the installation is performed in a state in which the locking protrusion 200a protruding from the end side is in contact with the first stopper part 201a of the stopper member 201. (the state shown in Fig. 18) or the state in which it is in contact with the second stopper portion 201b (the state shown in Fig. 18)
They are designed to rotate and displace integrally so that they are in the state shown in the figure).

Furthermore, a power supply terminal 204 made of a conductive plate spring connected to the bias voltage 192 via a bias terminal 202 and a cord 203 is disposed on the path of movement of the power-fed part 2θoh of the lever 200. The power supply terminal 204 and the power supply portion 200b of the lever 200 constitute the contact 190 (191).

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

Therefore, as shown in FIG.
When in contact with (when the developer magnetic brush is not formed),
The contact 191 (192) is in the open state, and the first
As shown in FIG. 9, when the second stopper portion 201bK is in contact (when forming the developer magnetic brush), the contact 191 (
192) is in a closed state.

Then, as shown in FIG. 17(a), the second developing device 1
6b is selected and the developer magnetic brush 135 is applied to the surface of the second developing roller 131°! is formed, the first contact 190 is open, the second contact 191 is closed, and the second developing roller 131. The developing bias is applied only to.

In addition, as shown in FIG. 17 (bl), the first developing device 16
a is selected and the developer magnetic brush 135.a is applied to the surface of the first developing roller l311. is formed, the first contact 190 is closed, the second contact 191 is open, and a developing bias is applied only to the first developing roller l311.

In this way, while the selected developing device 16a (16b) is operating, the developing bias of the other developing device 1 fi b (76a) is cut, and the developing device 16b (16b) which is not used is cut off.
m) developer magnetic bra v r s s s! (rss,) 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 second developing device 16m is connected to the developer stirring body 140! Opposed to the central part in the longitudinal direction, and the head part 211
The detection surface 211a of the sensor is provided in a vertical state.

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 built-in, and the magnetic permeability changes depending on the mixing ratio of the developer G flowing on the surface of the detection surface 112a, the magnetic carrier C2 and the non-magnetic toner rl+. The concentration of the toner T2 in the developer G2 is detected by converting the change to the change in the magnetic field created by the coil to the change in the inductance of the coil.

Compared to the conventional probe, in which the toner T is attached to the probe, the toner T is irradiated with light, and the toner concentration in the developer G is detected by the reflected light, a separate drive mechanism is not required. The density detection device and its accompanying installation can save space, do not require regular maintenance due to the detection unit becoming dirty due to toner scattering, etc., and are not affected by changes in the environment and can provide stable toner. Concentration detection is now possible.

Note that the toner concentration detector 43 of the first developing device 161 also has a similar configuration. Further, as shown in FIG. 23, the developer stirring body 140 of the second developing device 1sa. is counterclockwise (arrow a) opposite to the direction of rotation of the sleeve 144t.
direction) to scrape up the developer G from below.

For example, as the number of copies is accumulated around the carrier C2, a melt of toner T (spent toner) is formed, and the flow rate of the developer Gt changes, causing the toner concentration detector 4
Developer G in the arrangement part 4! The flow of the
Scraper 139. Even if the amount of developer G accumulates on the top and changes slightly, the entire detection surface 211a of the toner concentration detector 44 is always filled with developer G! In this state, stable toner concentration detection can be performed.

Furthermore, the sensitivity of the toner concentration detector 44 is determined by the detection surface 211a of the toner concentration detector 44 and the developer stirring body 140! Although it varies depending on the gap H between the two, based on the experimental data shown in FIG. 24, it is set to 5 m or less in order to maintain an appropriate image density and to ensure stable detection operation.

Note that the developer G is the developer agitator 140. Since the developer G! is scraped up correctively by the detector 44, the developer G! The flow of the developer G is not affected by heavy equipment, and control will not go out of order even with slight changes in gravity.

Further, as shown in FIG. 25, the developer G! from the developing roller 1312! Scraper 139 to separate! The first inclined portion 139 is formed in a dogleg shape and separates the developer G. a
and a second inclined part 1391b which has a steeper inclination than this and which guides the separated developer G to the developer agitating member Z 40t.

Further, the rear end position of the second inclined portion 139vb 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 (45 degrees in θ) with respect to the horizontal line a. and the second inclined portion 139tb and the developer stirring body 140. A V-shaped space A is formed between the second inclined portion 1391b and the casing 14I! The gap H between the two is regulated.

Therefore, the first inclined portion 139. , the developing roller 13
1. The developer Gt separated from the second inclined portion 139 . Developer agitator 140 by b! Guided by the developing roller 131! developer G separated from
The developer storage portion 1 is removed without remaining on the scraper 139°.
It will be smoothly guided to 38t. Also, space A
As a result, the developer G! after use is formed. By increasing the agitation time between the toner T and the supplied toner T, and by regulating the gap H, it is possible to reduce the amount of toner T that is generated when the toner T that is insufficiently agitated is led out by the developing roller 131°k. This will prevent scattering.

Also, scraper Z39. Not limited to the dogleg shape, but also the second shape.
As shown by the two-dot chain line, a flat scraper 139 is used.
．． ' has the same effect.

Further, as shown in FIG. 25, the developing roller 131! and scraper 139. A gap C of approximately 5m+ is formed between the developer E and the brush 135! Among them, the outer developer G2 that contributes to development is scraped with a scraper 139!
The developer stirring body I40. The remaining developer G, which does not contribute to the phenomenon, is removed by the unseparated magnetic brush 13.5. '
The image is rotated while remaining on the surface of the developing roller 1312.

In this way, the unseparated magnetic brush 135. on the surface of the developing roller 13z. ' If you actively leave this unseparated magnetic brush 135. ' becomes magnetized as it rotates, and the developer storage section 13
8. The suction force (force in the direction indicated by arrow A) of the developer G from the developing roller 131! increases, and the developing roller 131! The developer G is evenly supplied to the target area.

Therefore, the developing roller 131! By supplying the developer Gt evenly, it is possible to reliably prevent uneven development due to uneven supply of the developer.

Further, the second developing device 16b has a standard 5oo II
Developer G! is stored, but the ratio of toner T and carrier C1 is the weight removal ratio: toner: carrier = 4:
The ratio is 100.

Further, the carrier C2 has a conventional particle size of 74 μm to 1 μm.
50 μm, the surface is not a set 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) C1 is used.

Note that FIG. 26 shows the relationship between the number of copies and changes in various items due to differences in particle size of carrier C1.
It can be seen that the image density and charge amount are stabilized by using carrier Ct with a small particle size. Note that if the proportion of the carrier C3 having a fine C particle size of 44 μm or less is increased, the absolute value of the amount of charge of the carrier C1 becomes too large, lowering the image density and shortening the life.

In addition, as shown in Table 1 below, carrier C with a particle size of 44 μm or less! If the proportion of is increased, it is undesirable because scratches on the photoreceptor drum 13 and black spots occur, but when it is less than 10% by weight, no black spots were observed even after copying after 40,000 copies.

The table also shows that when using the ferrite carrier C1, in which the proportion of fine surface crystals with a particle size of 44 μm or less is 10% by weight or less, and the small particle size has a peak of 44 to 105 μm, the toner has a long life. It has the effect of reducing scattering and providing highly detailed image quality, as well as the second
Standard developer storage in the developing unit 16b!
In contrast, the storage amount of developer G2 is reduced to about 300g (30%
It was confirmed that even if development was carried out in a state where the amount was reduced, there was no change at all, and good development was carried out.

Note that similar results were obtained in the first developing device 16a by using the same carrier C3 as the carrier C7 used in the second developing device 16b.

Furthermore, Figure 27 shows the relationship between the number of copies and the change in fog due to the difference in toner particle size.
) It can be seen that fogging is reduced by using toner TI (T, ) with a small particle size of 2L or less.

Therefore, this small particle size toner T, (T,) is made of the above-mentioned fine surface crystals with a proportion of 10% by weight or less of particles with a particle size of 44 μm or less, and a small particle size with a peak of 44 to 105 μm. By using it in addition to the ferrite carrier C, (C,), further stability of image density can be obtained. (See Figure 26) The reason for this is that the charging of toner T, (T,) is different from the microscopic point of view when one particle of toner T, (T,) is charged by carrier CI (C2).
) by rubbing against one crystal on the surface. Therefore, the surface of carrier C, (C,) is fine,
and uniform, toner T from carrier C1 (C,)
, (T,) is smaller than that of a carrier with normal surface crystals, the charging of toner TI(T,) is smaller than that when using a carrier with normal surface crystals. and the absolute value of the amount of charge becomes small.

In this way, if small particle size carriers C, (C,)K and small particle size toners T, (T, Smearing and fogging can be prevented, and since the amount of charge becomes uniform, the image density becomes stable. It was confirmed that even if development was carried out with the amount of developer G reduced by about 300 g (about 30%) compared to 500 g, good development was achieved with no significant change.

Note that similar results were obtained in the first developing device 16a by using the same carrier C1 as the carrier C2 used in the second developing device I6b.

〔Effect of the invention〕

As explained above, the present invention provides a two-component developer consisting of a toner and a carrier, in which the proportion of the carrier that is a fine surface crystal and has a particle size of 44 μm or less is 10% by weight or less, and the particle size is 44 to 105 μm. By using a carrier with a small particle size that has a peak of Even if development is performed in a reduced state, there is no change at all, and it is possible to provide a developer that allows good development.

[Brief explanation of drawings]

FIG. 1 is an external perspective view of an image forming apparatus to which an embodiment of the developing device using the developer of the present invention is applied, FIG. 2 is a schematic longitudinal sectional front view, and FIG. 3 is an internal mechanism seen from the rear side. Figure 4 is a diagram showing the upper unit in an open state, Figure 5 is an explanatory diagram schematically showing the driving force transmission system, Figure 6 is a plan view of the operation panel, and Figure 7 is the fixing device. Explanatory diagrams schematically showing the nearby exhaust system, Figures 8 to 25 show the developing device, Figures 8 and 9 are longitudinal sectional front views showing different operating states, and Figure 10 shows the magnetic FIG. 11 is a side view of the magnetic roll driving means, FIG. 12 is an explanatory diagram showing the operating state of the magnetic roll driving means, and FIG. 13 is a partial cross-sectional view of the magnetic roll driving means. A perspective view of the magnet used, FIG. 14 is an explanatory diagram showing the magnetic field line direction of the magnet shown in FIG. 1st. FIG. 17 is an explanatory diagram showing the state of gap formation in the second developing roller; FIG. 17 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 bias cutting means;
FIG. 19 is an explanatory diagram showing the operating state, FIG. 20 is a schematic vertical sectional front view of the second developing device, FIG. 21 is a strategic cross-sectional plan view, and FIG. 22 is a perspective view of the toner concentration detector. Fig. 23 is a side view showing how the toner concentration detector is installed, Fig. 24 is an explanatory diagram showing the relationship between toner density and detector output, and Fig. 25 shows the shape of the scraper and the state of gap formation with respect to the developing roller. An explanatory diagram, FIG. 26 is an explanatory diagram showing the relationship between the number of copies and various i-th changes due to differences in carrier particle size, and FIG. 27 is an explanatory diagram showing the relationship between the number of copies and changes in fog due to differences in toner particle size. FIG. G1. G! ...developer, CI+CI...carrier,
T,,T,...toner. Applicant's Representative Patent Attorney Takehiko Suzue Figure 1 Figure 10 Figure 12 (a) (b) Figure 15 Figure 16 Figure 17 Figure 18 Figure 19 Figure 20 Figure 22) j-i1 Foreword: Figure 25: Figure 26: A Mosquito (↑Ko) Figure 27: A Mosquito (↑Ko)

Claims (3)

[Claims] (1) In a two-component developer consisting of a toner and a carrier, the proportion of the carrier that is a fine surface crystal with a particle size of 44 μm or less is 10% by weight or less, and the particle size is small with a peak of 44 to 105 μm. A developer characterized by using a carrier. (2) The small particle size carrier is nickel, zinc, barium,
The developer according to claim 1, characterized in that it is made of any manganese-based ferrite carrier. (3) The developer according to claim 1, wherein the mixing ratio of toner and carrier is a weight ratio of toner:carrier=4:100.