JPH02251875A - Developing device - Google Patents

Abstract

PURPOSE:To prevent the occurrence of breakdown with a simple constitution by setting a voltage applied to a developing sleeve, a voltage applied to a toner replenishment member, a voltage just before the breakdown of carriers, etc., in such a way that they satisfy the specific condition. CONSTITUTION:VB is a voltage applied to the developing sleeve 2, VH is a voltage applied to the toner replenishment members 3-9, VBD is a voltage just before the breakdown of the carriers, RBD is a resistance just before the breakdown of the carriers, and RH is a resistance between the part where a voltage is applied to the toner replenishment members 3-9 and the part where the members 3-9 come into contact with two-component developer. The applied voltages VH and VB are set in such a way that the absolute value ¦VH-VB¦ of a difference between the applied voltages VH and VB satisfies equation I. Thus, breakdown between the developing sleeve 2 and the replenishment members 3-9 can be prevented, and toner is securely supplied to developer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a developing sleeve carrying a two-component developer having toner and a carrier; The toner is brought into contact with the two-component developer on the developing sleeve, and the two-component developer on the developing sleeve is brought into contact with the two-component developer on the developing sleeve due to the potential difference between the magnetic means and the two-component developer on the developing sleeve. and a toner replenishing member for replenishing toner, and by rotating at least one of the magnetic pole of the magnet means and the developing sleeve, the two-component developer carried on the developing sleeve is transported, and the two-component developer carried on the developing sleeve is The present invention relates to a developing device that visualizes an electrostatic latent image formed on a latent image carrier using toner.

[Conventional technology]

The use of the above-mentioned type of developing device in image forming apparatuses such as electronic copying machines, printers, and facsimile machines is conventionally known (see, for example, Japanese Patent Laid-Open No. 59-113463 and Japanese Patent Application Laid-open No. 59-111663).

[Problem to be solved by the invention]

In this type of developing device, a voltage is applied to each of the toner replenishing member and the developing sleeve, and the potential difference between them causes
The toner on the toner supply member is transferred to the developing sleeve side, and the toner is supplied to the two-component developer. At this time, depending on the potential difference between the developing sleeve and the toner replenishing member, breakdown (leakage) occurs through the carrier existing between the two. In other words, the developing sleeve, the developer, and the toner replenishing member become electrically conductive, and the voltages applied to each of the developing sleeve and the toner replenishing member follow whichever has the higher absolute value, and both become at the same potential. This means that a predetermined potential difference cannot be obtained between the developing sleeve and the toner supply member.

If such a situation occurs, it becomes impossible to replenish the toner on the toner replenishing member to the two-component developer on the developing sleeve side.

Also, one of the purposes of applying a bias voltage to the developing sleeve is to form a predetermined electric field between the sleeve and the latent image carrier, and to protect the background part (other than the electrostatic latent image) of the latent image carrier. The purpose is to prevent toner from adhering to the surface of the surface of the surface of the surface of the surface of the surface of the surface of the surface of the surface of the surface of the surface of the surface of the surface of the surface of the surface of the surface.

However, when replenishing toner, a higher voltage is applied to the charged polarity side of the toner particles to the toner replenishing member than to the developing sleeve, so breakdown occurs between the developing sleeve and the toner replenishing member as described above. When this occurs, the voltage applied to the toner replenishing member is also applied to the developing sleeve, the voltage of the sleeve becomes equal to the voltage of the toner replenishing member, and the voltage of the developing sleeve is increased. Namely.

The voltage of the developing sleeve will deviate greatly from the predetermined voltage determined by the relationship between the electrostatic latent image of the latent image carrier and the surface potential of the background, which will cause abnormalities in the developed image. be.

In addition, when a low-resistance carrier with particularly low resistance is used as a carrier in a two-component developer, a resistive layer such as a rubber layer is provided on the surface of the toner replenishing member, so that the developing sleeve and the toner replenishing member are Maintaining a predetermined potential difference between
Toner on the toner supply member can be electrostatically transferred to a developer carrier on the developer sleeve. However, in this case as well, there is a risk that the aforementioned breakdown phenomenon may occur due to the resistance value of the resistor layer or the potential difference between the developing sleeve and the toner replenishing member.

The object of the invention is to provide a developing device of the type mentioned at the outset, in which the occurrence of the breakdown described above can be prevented by a simple construction.

[Means to solve the problem]

In order to achieve the above object, the present invention sets the voltage applied to the developing sleeve to VB, the voltage applied to the toner replenishing member to VH, the voltage on the verge of carrier breakdown to VBD, the resistance on the verge of carrier breakdown to RBD, and the toner When the resistance between the voltage application part of the supply member and the part where the member contacts the two-component developer is R1, the applied voltage vH and v
We propose a configuration in which applied voltages vH and vB are set so that the absolute value IVHVBl of the difference in B satisfies the following.

In addition, when the developer carrier used is a particularly low-resistance carrier, the voltage applied to the developing sleeve is VH, the voltage applied to the voltage application part of the toner replenishing member is V)l, and the voltage on the verge of breakdown of the carrier is set to VH. VBD is satisfied, where RBD is the resistance on the verge of breakdown of the carrier, and RH is the resistance between the voltage application part of the toner replenishing member and the surface of the resistor layer that contacts the two-component developer on the developing sleeve. It is preferable to set the resistance R, as follows.

〔Example〕

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

In FIG. 1, the developing device of this embodiment includes a toner tank 1 stocking toner, a developing sleeve 2, a toner replenishing roller 3 which is an example of a toner replenishing member, a toner supply roller 4, a first screw 5, a toner replenishing roller 3, a toner supply roller 4, a first screw 5, 2 screw 6, elastic blade member 7, sealing material 8. The developing sleeve 2 has a drum-shaped photoreceptor 1o.
is facing. The toner is a powder consisting of toner particles alone or with additives added thereto. The photoreceptor 1o constitutes an example of the structure of a latent image carrier, and the photoreceptor 10 is rotated clockwise.

A fixed magnet group 12, which is an example of magnetic means, is arranged inside the developing sleeve 2, and the magnetic poles of the magnet group 12 in the circumferential direction of the developing sleeve are arranged as shown in FIG. Due to the magnetic force of the magnet group 12, a two-component developer consisting of a magnetic carrier and toner is carried on the surface of the developing sleeve 2, and as the developing sleeve 2 rotates counterclockwise, the developer is carried on the sleeve 2. The two-component developer (hereinafter simply referred to as developer) is conveyed counterclockwise, and after its height is regulated by the doctor blade 9, it is transferred to the developing area between the developing sleeve 2 and the photoreceptor 10. carried. Here, the toner in this developer electrostatically transfers to the electrostatic latent image formed on the photoreceptor 1o, making the latent image visible.

The developing sleeve 2 is made of a conductive non-magnetic material such as aluminum, and a bias voltage is applied to the sleeve 3 by a power source 13. As the carrier in the developer, for example, iron powder or particles thereof coated with resin are used.

The developing sleeve 2 is fixed immovably, and the magnet group 12 is installed instead.
For example, the developer carried on the developing sleeve 2 can be conveyed by rotating the developing sleeve 2 clockwise, or by rotating the developing sleeve 2 and the magnet group 12 together.

When the above-described developing operation is performed, the test pattern previously formed on the photoreceptor 10 is also developed, and the optical density of the visualized test pattern is detected by the image density detection element 11 consisting of a photosensor or the like. . This detection result is compared with the reference concentration level, and the current toner concentration in the developer is determined. If it is determined that the toner concentration is low, the developing sleeve 2
The toner supply roller 3 located close to rotates in the direction of the arrow.

The toner supply roller 4 , the elastic blade member 7 , and the sealing material 8 are in pressure contact with the toner supply roller 3 over the entire circumferential surface and axial direction, and the toner in the toner tank 1 is in contact with the toner supply roller 3 . The toner is rubbed onto the toner supply roller 3 by the toner supply roller 4 rotating at the same time, the toner is conveyed as the toner supply roller 3 rotates, and is continuously formed into a thin layer on the toner supply roller 3 by the elastic blade member 7. It looks like this. The thin layered toner undergoes a series of frictional actions that cause the toner particles to have a predetermined polarity.
In this example, the toner is charged to a negative polarity and comes into contact with the developer carried and conveyed on the developing sleeve 2 . At this time, as will be described in detail later, the toner on the toner replenishing roller 3 is taken into the developer on the developing sleeve 2 due to the potential difference between the developing sleeve 2 and the toner replenishing roller 3. In this way, toner is replenished into the developer, and the toner concentration in the developer is maintained within a certain range.

The toner supply roller 3 includes a core member 3a made of a conductive material such as metal, and a resistor layer (laminated and fixed on the core member 3a).
Surface layer) consists of 3b. Examples of the material for the resistor layer 3b include rubber materials such as carbon-mixed NBR and trill rubber), silicone rubber, and resin materials such as fluororesin.

Alternatively, the toner replenishing roller 3 may be entirely made of metal such as aluminum or stainless steel without providing a resistor layer.

The elastic blade member 7 may be made of a material having appropriate elasticity, such as a thin sheet metal such as carbon steel, rubber such as silicone, or resin such as fluororesin.

Further, the toner supply roller 4 may be a metal core wound with a conductive treatment such as carbon dispersed in foamed polyurethane.

Note that the toner supply roller 3 and the toner supply roller 41
The material for the elastic blade member 7 is selected in consideration of the charging polarity of the toner particles, the required amount of charging, and the like.

Upstream of the doctor blade 9, the developer regulated by the doctor blade 9 forms a developer pool P, and near this pool P there is a first screw 5.
is installed close to the developing sleeve 2. The first screw 5 rotates together with the developing sleeve 2, and transports the developer in the pool P toward one end in the axial direction (in this embodiment, toward the front in the drawing), and the developer sent toward the front is A block (not shown) is formed at the front end, and when the amount exceeds a certain level, it enters the screw cover 15 which has a notch (not shown) at the front end.

A second screw 6 is installed inside the screw cover 15, and the winding direction and rotation direction of the second screw 6 are set so that the conveyance direction of the second screw 6 is opposite to the conveyance direction of the first screw 5. ing. Therefore, the developer that has entered the screw cover 15 is then conveyed inside the screw cover 15 to the back side in the drawing by the second screw 6. Then, the developer falls onto the developing sleeve 2 again through a notch (not shown) formed at the bottom of the rear end of the screw cover 15 .

By circulating and agitating the S developer in the axial direction of each member, it is possible to alleviate differences in toner consumption due to development, and it is possible to always send developer with even toner concentration to the development area. .

As described above, the frictionally charged toner is carried on the surface of the toner replenishing roller 3, and the developer on the developing sleeve 2 comes into contact with the toner replenishing roller 3.

The toner on the toner replenishing roller 3 is replenished into the developer by the potential difference between the developing sleeve 2 and the toner replenishing roller 3. To explain this in a little more detail, the developing sleeve 2 is powered by the power supply 13 as described above, for example. -600(V
) is applied to the voltage application portion of the toner supply roller 3, that is, the conductive core member 3a in this example,
For example, a bias voltage of -800 (V) is applied by the power supply 16, and the toner particles of negative polarity on the toner supply roller 3 are drawn to the developer side on the developing sleeve due to the potential difference between the two, and the toner is absorbed into the developer. supplied to

In this way, toner is replenished by the potential difference between the developing sleeve side and the toner replenishing roller side, so as explained earlier, the developing sleeve 2 and the core member 3a of the toner replenishing roller 3 are in a conductive state, that is, breakdown. occurs.

There is no potential difference between them, and toner cannot be replenished. Further, when such a breakdown occurs, the voltage applied to the core member 3a of the toner replenishing roller 3 is also applied to the developing sleeve 2, causing an abnormality in the visible image formed on the photoreceptor 10.

The present invention prevents the above-mentioned breakdown from occurring by regulating the bias voltage applied to the toner supply roller and the developing sleeve.

That is, taking into consideration the fact that the smaller the resistance between the developer and the resistor layer 3b, the easier it is to break down, the bias voltage ( The bias voltage VH1 (hereinafter also referred to as replenishment bias) applied to the developing sleeve 2 is VB (hereinafter also referred to as developing bias), causing breakdown of carriers in the developer existing between the developing sleeve 2 and the toner replenishing roller 3. The voltage on the verge of VBD,
The resistance on the verge of breakdown of the carrier is RBD, and the resistance between the voltage application part of the toner replenishing roller 3 and the part where the roller contacts the developer (in this example, the resistance between the resistor 1 part in contact with the core member 3a and the developer) The applied voltages vH and VB are set so that the absolute value of the difference between the replenishing bias VH and the developing bias VB (IV)l - VBL satisfies the following: ing.

Second, just before the carrier breaks down, the current flowing between the core member 3a of the toner replenishing roller 3 and the developing sleeve 2 is I wax, and the resistor that also contacts the core member 3a and the developer just before the carrier breaks down. If the potential difference between the layer surface and the voltage applied to the resistor layer 3b is Vhn+ax, then equation (1) can be rewritten as follows.

Vl(VBI≦Imax−RH×VBD (2
)moreover.

l VH-VBl≦Vhmax+VBO (3) As can be seen from these equations, the first item on the right side is the resistor 113b on the verge of the developer (carrier) breaking down.
Similarly, the second item on the right side shows the voltage drop in the developer (carrier) on the verge of breakdown, and if l VH - VBl is set above the sum of these, the voltage drop between the developing sleeve 2 and the toner Breakdown can be prevented from occurring between the supply roller 3 and the core member 3a.

Note that when a roller without a resistor layer 3b, that is, a roller with an exposed metal core member 3a, is used as the toner supply roller 3, RH=0, and equation (1) becomes the following equation (4). It becomes like this.

If this is satisfied, breakdown can be prevented from occurring.

IVHVBI≦V BD (
4) Next, we will show an example of the procedure for actually determining the developing bias vB and replenishment bias vH so as to satisfy formulas (1) to (3), and clarify what these formulas mean more specifically. do.

FIG. 2 shows a method of measuring the characteristic values of the carrier of the developer actually used in the developing device shown in FIG. 1, and the graph shown in FIG. 3 shows the measurement results.

In FIG. 2, a developing sleeve 2, which is the same as the developing sleeve shown in FIG. is installed. The gap between the developing sleeve 2 and the metal roller 103 is also the same as the gap between the developing sleeve 2 and the toner supply roller 3 shown in FIG. 1, and the developing sleeve 2 shown in FIG. The magnetic carrier C is supported by magnetic force in the same state as the agent. In the developing device illustrated in FIG. 1, the gap between the developing sleeve 2 and the toner supply roller 3 is 1.3 m, f
The gap between the i-image sleeve 2 and the doctor blade 9 is 0.
Although the carrier C is set to 7 mm, the carrier C is set to the metal roller 103 in FIG.
It comes into contact with.

In addition, a high resistance meter 2 is attached to the metal roller 103 and the developing sleeve 2.
1 is connected, and thereby the resistance value of the carrier C is measured when the potential difference between the voltages applied to the metal roller 103 and the developing sleeve 2 (hereinafter referred to as applied voltage Vc) is changed. The results are shown in the graph of FIG. 3, in which the horizontal axis represents the applied voltage Vc and the vertical axis represents the resistance value of the carrier C. Note that FIG. 3 shows the resistance values measured 30 seconds after the start of application of the voltage Vc.

Here, as shown by the X mark in FIG. 3, when the applied voltage Vc reaches about 38 (V), the carriers undergo breakdown, and the resistance value rapidly decreases, making it impossible to measure. The voltage that causes such a breakdown (approximately 38
The applied voltage just before v) and the resistance of the carrier C at this time are the above-mentioned VBD and RBD, and the ratio V so /
RBD is I wax.

In other words, the current I n+ax can be said to be the maximum current value that can be passed through the carrier C without causing breakdown. In other words, the carrier C will break down if a larger current is applied to it than the carrier C.

As mentioned above, we measured the resistance value of only the carrier C, not the resistance value of the developer (a mixture of toner and carrier) used in the actual developing device shown in Figure 1. Since the carrier alone has a lower resistance and is more likely to cause breakdown, it is better to measure the resistance value of the carrier C and set the above-mentioned formula (1) based on this.
This is because it is possible to set a value on the safe side for breakdown.

Next, FIG. 4 is an explanatory diagram showing a method of measuring the resistance value of the resistor layer 3b of the toner supply roller 3. Toner supply roller 3
The metal plate 23 is in contact with the resistor 13b of the roller 3 in the same range as the developer contacts with the resistor 13b of the roller 3 in the developing device shown in FIG. Also, a high resistance meter 21 is connected between the metal plate 23 and the conductive core member 3a of the toner supply roller 3, and thereby the resistance value R of the resistor layer 3b sandwiched between the metal plate 23 and the core member 3a is measured. be measured. The result is the graph shown in FIG. In this case as well, the resistance value is measured 30 seconds after the start of voltage application.

The applied voltage vh on the horizontal axis of this graph is the voltage applied to the resistor layer 3b, that is, the voltage applied to the metal plate 2 by the high resistance meter 21.
3 and the voltages applied to the core member 3a.

Note that the resistance R of the resistor layer 3b of the toner supply roller 3 can be adjusted by appropriately selecting the amount and type of carbon mixed into the resistor layer 3b. Normally, when this roller 3 is installed and used in a developing device as shown in Figure 1, a counter charge is generated on the surface of the toner replenishing roller due to the charge of toner particles electrostatically attached to its surface. When the toner is peeled off from the surface of the toner supply roller, the counter charge is set to a resistance value that makes it easy to escape. Also, by changing the material of the resistor layer 3b,
The situation in which the resistance value changes is shown in detail in, for example, Figure 7, page 575 of the Japan Rubber Association Journal, Vol. 58, No. 9 (1985).

Here, from the graph shown in FIG. 3, the voltage VBD on the verge of carrier breakdown is 36 (
V), and its resistance RBD can be selected to be 1.5×10' (Ω). Therefore, the current Iwax on the verge of breakdown is Imax=240 (μA).

Next, the graph shown in FIG. 6 is a graph showing the relationship between the applied voltage vh converted from the graph shown in FIG. 5 and the current Vh/Rh flowing through the resistor M3b. When Imax=240 (μA), the voltage Vh applied to the resistor layer 3b is 270 (V). The resistance R of the resistor layer at this time is about 1. It becomes lXl06 (Ω).

Substituting each of the above values into formula (1), we get = 306 (V) (5).

Here, the developing bias vB and the replenishment via XV are as shown in the example above.
), and Li”mi6.

VH-VB l = I (800) (-600)
1=200 (6), which satisfies equation (5). That is, if vB and vH are set as exemplified above, breakdown will not occur at all, and the occurrence of insufficient toner replenishment to the developer and abnormal visible images can be prevented. This has also been confirmed through experiments.

In addition, the actual developing bias Va and replenishment bias ■H are as follows:
While satisfying formula (1), it is determined by taking into account factors such as the density of the original to be copied, the visible image density desired by the operator, the charging polarity of the toner particles, and the ability to stably replenish toner to the developer. be done.

The general method for measuring the resistance value of a carrier is to fill a certain volume with the carrier and measure the resistance of the carrier between two flat electrodes. The purpose of measuring the carrier is to obtain the resistance value of the carrier in a state closer to that of an actual developing device.

Similarly, the resistance value of the resistor layer 3b of the toner replenishing roller 3 is normally measured as specified by JIS etc., and the resistor layer alone is measured. By measuring, it is possible to measure in a state closer to the actual developing device, and accurate measurement results can be obtained.

FIG. 1 shows a configuration in which the toner replenishing roller 3 has the resistor layer 3b, but as described above, (
Equation 1) can also be applied when using a toner replenishment roller 3 without a resistor layer, that is, a toner replenishment roller 3 in which the core member 3a made of a conductor is exposed (in this case, RH=
O). However, when a carrier with particularly low resistance is used, if the toner replenishment roller 3 does not have the resistor layer 3b, the developing sleeve 2 and the toner replenishment roller 3
However, since conduction is likely to occur through the low-resistance carrier, it becomes difficult to maintain a potential difference between the two. Therefore, when a developer containing a low-resistance carrier is used, it is necessary to use a toner supply roller 3 having a resistor layer 3b.

However, even if the toner replenishment roller 3 having the resistor layer 3b is used, depending on its resistance value, the breakdown described in detail earlier may occur, and the potential difference between the developing sleeve 2 and the toner replenishment roller 3 disappears, causing the toner to drain. This may cause problems such as not being able to replenish the developer.

Therefore, in the second embodiment of the present invention, a two-component developer containing a low-resistance carrier is used, and a resistor layer is used to prevent breakdown when a toner replenishment roller having a resistor layer is used. We propose a configuration that determines the resistance value of the layer.

In the second embodiment, the structure of the developing device itself is the same as that in FIG. 1. Here, as in the first embodiment, the voltage applied to the developing sleeve 2 is set to VB, and the conductive voltage application portion of the toner supply roller 3, that is, the conductive core member 3a in this example.
VH is the bias voltage applied to the carrier in the TR image, VBD is the voltage on the verge of breakdown of the carrier, RBD is the resistance on the verge of breakdown of the carrier, and When the resistance between the surface of the resistor layer 3b that contacts the developer, in other words, the resistance between the portion of the resistor layer that contacts the core member 3a and the surface of the resistor layer that contacts the developer, is R, The resistance R is determined so as to satisfy the following. Thereby, it is possible to reliably prevent breakdown from occurring between the developing sleeve 2 and the core member 3a.

Here, as explained earlier, Veo/REID=I
If max, equation (7) can be transformed as follows.

Then, equation (8) is 1, ≦Imax (10)
becomes.

The process H in equations (9) and (10) means that the resistance value of the developer existing between the developing sleeve 2 and the toner replenishing roller 3 is "0".
'', the current flowing between the developing sleeve 2 and the core member 3a of the toner supply roller 3 is shown. Such a current 1. is set below the current value Imax that allows the maximum flow of carriers without causing breakdown, as shown in equation (10). As a result, even if the resistance of the carrier is low and the resistance value is "0", breakdown does not occur between the developer and the resistor layer 3b, and the side of the developing sleeve 2 and the toner replenishing roller 3 are This makes it possible to maintain a potential difference with the conductive core member 3a, making it possible to replenish toner to the developer, and eliminating the possibility of abnormalities occurring in the visible image.

Next, an example of a method for determining the resistance RH so as to satisfy the equation (7) will be explained, and the meaning of the equation (7) will be clarified more specifically.

First, the measurement results shown in FIG. 3 are obtained using the apparatus shown in FIG. 2 in exactly the same manner as in the first embodiment. Note that the carrier C used here is a low resistance carrier.

From the graph in Figure 3, it can be seen that the carrier C used was approximately 38 (
Breakdown occurs at the applied voltage Vc of V), and VBD=3
6 (V) and Rso=1.5X10' (Q), which is the same as in the first embodiment.

Therefore, VB=-600 (V) and VH=-
Assuming that 850 (V) (1) A ear Xit pressure is applied, equation (7) is R, ≧1.0X10@(Ω)
(11), that is, a resistance R that satisfies equation (11).

By using the resistor layer 3b, it is possible to prevent breakdown from occurring.

On the other hand, similarly to the first embodiment, the resistor layer 3b of the toner replenishing roller 3 actually used in the apparatus shown in FIG.
Measure the resistance at . At this time, for example, if aluminum is used as the core member 3a of the toner supply roller 3 and rubber with a thickness of 1.5 m is used as the resistor layer 3b,
According to experiments, the voltage vh applied to this resistor layer 3b is 2
50 (V), the resistance value R of the resistor layer 3b,
was 1°4×10' (Ω), and this value satisfies equation (11). In experiments actually conducted using the toner replenishing roller 3 having such a resistor layer 3b, no toner replenishment failure due to breakdown (leakage) or abnormal images were observed.

The present invention can be widely applied to a developing device using a belt instead of a toner replenishing member consisting of a toner replenishing roller.

〔Effect of the invention〕

According to the configuration described in claim 1, it is possible to prevent breakdown between the developing sleeve and the toner replenishing member, reliably replenish toner to the developer, and prevent abnormal images from occurring.

According to the configuration described in claim 2, occurrence of breakdown can be prevented even when a low resistance carrier is used as a carrier in the developer.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example of a developing device according to the present invention, FIG. 2 is an explanatory diagram showing a method for measuring the resistance of a carrier, FIG. 3 is a graph showing an example of the measurement results, and FIG. 4 is a graph showing an example of the measurement results. is an explanatory diagram showing a method for measuring the resistance of the resistor layer of the toner replenishment roller, FIG. 5 is a graph showing an example of the measurement results, and FIG. It is a graph showing the relationship between current and applied voltage. 2...Developing sleeve 3b...Resistance body agent Patent attorney Norio Hoshino Figure 2 Figure 3 Figure 1: l'/XI'+UVC (V)

Claims (2)

[Claims] (1) A developing sleeve that supports a two-component developer containing toner and a carrier, and a magnet that is installed inside the sleeve and applies magnetic force to the two-component developer to cause the developer to be supported on the developing sleeve. and a toner replenishing member that brings the toner into contact with the two-component developer on the developing sleeve and replenishes the toner to the two-component developer on the developing sleeve by a potential difference with the developing sleeve. By rotating at least one of the magnetic pole and the developing sleeve, the two-component developer carried on the developing sleeve is transported, and the toner in the developer causes
In a developing device that visualizes an electrostatic latent image formed on a latent image carrier, the voltage applied to the developing sleeve is V_B, the voltage applied to the toner replenishing member is V_H, and the voltage applied to the toner replenishing member is V_H. When the voltage is V_B_D, the resistance on the verge of carrier breakdown is R_B_D, and the resistance between the voltage application part of the toner replenishing member and the part where the member contacts the two-component developer is R_H, the applied voltage V_H The absolute value of the difference between
Apply voltages V_H and V to satisfy _H+V_B_D.
A developing device characterized in that _B is set. (2) A developing sleeve that supports a two-component developer having toner and a carrier, and a magnet that is installed inside the sleeve and applies magnetic force to the two-component developer to cause the developer to be supported on the developing sleeve. a conductive voltage applying section and a resistor layer provided on the surface thereof, the toner is brought into contact with the two-component developer on the developing sleeve, and due to the potential difference between the voltage applying section and the developing sleeve, and a toner replenishing member for replenishing toner to the two-component developer on the developing sleeve, and by rotating at least one of the magnetic pole of the magnet means and the developing sleeve, the two-component developer carried on the developing sleeve can be produced. In a developing device that conveys a developer and visualizes an electrostatic latent image formed on a latent image carrier by toner in the developer, the voltage applied to the developing sleeve is set to V_B, and the voltage applied to the toner replenishing member is set to V_B. The voltage applied to the voltage application section is V_H, the voltage at which the carrier is on the verge of breakdown is V_B_D, the resistance at which the carrier is on the verge of breakdown is R_B_D, and the two-component developer on the voltage application section of the toner replenishing member and the developing sleeve is applied. When the resistance between the contacting resistor layer surface and the surface is R_H, R_H≧(R_B_D・|V_H−V_B|)/V_B
A developing device characterized in that a resistance R_H is determined so as to satisfy _D.