JP2002049233A - Developing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that conventionally surface staining occurs. SOLUTION: If assumed that maximum potential at moving of developer on a developer carrier 40a toward an electrostatic latent image carrier 10 is Vmax; the non-image part potential of an electrostatic latent image is VD; the difference between VD and Vmax is ΔVD; the shortest distance between the image carrier 10 and the developer carrier 40a is d[m]; the average value of charge per one developer is Qm[C], the duty of developing bias is 'duty' and the frequency of the developing bias is f[Hz], (f) satisfies relation (1).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing method, a developing apparatus, a copying machine, a printer and a facsimile for developing an electrostatic latent image on an electrostatic latent image carrier with a one-component developer on a developer carrier. And the like.

[0002]

2. Description of the Related Art Conventionally, in an electrophotographic image forming apparatus, usually, an electrostatic latent image is first formed on an electrostatic latent image carrier,
A method of visualizing the electrostatic latent image with toner in a developing device is adopted. In recent years, as an electrostatic latent image forming method for forming an electrostatic latent image on an electrostatic latent image carrier, a semiconductor laser is applied to the electrostatic latent image carrier after the electrostatic latent image carrier is uniformly charged. The method of writing by using a light source such as the above and forming an electrostatic latent image has become mainstream.

As a method for visualizing an electrostatic latent image on an electrostatic latent image carrier, a one-component type toner or a two-component type developer obtained by mixing toner and carrier particles is used. A contact development method in which the electrostatic latent image on the electrostatic latent image carrier is developed by rubbing against the electrostatic latent image on the carrier, and the toner is carried from the toner carrier to the electrostatic latent image carrier by a developing electric field. A non-contact developing system for developing an electrostatic latent image on an electrostatic latent image carrier is known.

In the non-contact developing system, although conditions for obtaining a stable image are limited, it does not affect the electrostatic latent image itself. Therefore, a minute electrostatic latent image on the electrostatic latent image carrier is not affected. It is suitable for developing. In this non-contact developing method, a developing bias applied to a developing sleeve as a toner carrier is a main driving force when the toner is carried from the developing sleeve to the electrostatic latent image carrier.

As a method of applying the developing bias to the developing sleeve, there are a method of applying a developing bias to the developing sleeve by a DC power supply, and a method of applying a developing bias to the developing sleeve by an AC power supply. Various systems are known, such as a system for adjusting the voltage, frequency, and AC waveform of the developing bias. These development bias application methods include the size and shape of the system, the image formation method, the contrast of the electrostatic latent image, the particle size and distribution of the toner particles, the charge amount and distribution of the toner particles, and the environment in which the system is placed. The optimum value of the developing bias is set by various factors such as. For example, the AC bias application method of applying an AC bias to the developing sleeve as a developing bias can re-arrange the toner that has once developed the electrostatic latent image on the electrostatic latent image carrier,
Suitable for obtaining high image quality.

In a one-component flying development method in which an electrostatic latent image on an electrostatic latent image carrier is developed in a non-contact manner with a one-component developer on a developer carrier, development applied to the developer carrier is performed. A recording method and a recording apparatus for improving the image quality by regulating the bias frequency are described in JP-B-58-32377, JP-B-63-30622, and JP-A-6-194937.

[0007]

Among the above-mentioned developing methods, the contact developing method using a two-component developer is a widely used developing method, and a stable and stable image can be obtained. When a minute electrostatic latent image on the electrostatic latent image carrier is developed, the effect cannot be ignored. Further, in the AC bias application method, the toner may also move to a non-image portion of the electrostatic latent image on the electrostatic latent image carrier, and may cause background contamination.

In a developing method using a one-component toner, the toner in the non-image area cannot be peeled off by scavenging. Therefore, it is necessary to set the voltage and frequency of the developing bias and the charge amount of the toner to appropriate values. It is necessary to obtain high image quality. Further, in the one-component flying development method, the image quality is improved by regulating the frequency of the developing bias applied to the developer carrier. Not included.

It is an object of the present invention to provide a developing method with less background contamination. Claims 3 and 4
It is an object of the present invention to provide a developing device with less background contamination. An object of the invention according to claim 5 is to provide a developing device which can easily cope with colorization. An object of the invention according to claim 6 is to provide an image forming apparatus with less background contamination.

[0010]

In order to achieve the above object, the present invention is directed to an electrostatic latent image carrier for carrying an electrostatic latent image, and a developer for carrying a one-component developer. The electrostatic latent image on the electrostatic latent image carrier is developed with the developer on the developer carrier in a state where the developer is opposed to the carrier and a developing bias is applied to the developer carrier by a bias applying unit. In the developing method, the electric field due to the developing bias is an alternating electric field, and the maximum potential when moving the developer on the developer carrier toward the electrostatic latent image carrier is Vmax, The image portion potential is VD, the difference between the VD and the Vmax is ΔV _D , the shortest distance between the electrostatic latent image carrier and the developer carrier is d [m], and the electric charge per developer is The average value is Qm [C], and the developer on the developer carrier is electrostatically charged by the alternating electric field. The time during which the force for moving the image carrier is working is t1, and the force in the direction opposite to the direction in which the developer on the developer carrier is moved toward the electrostatic latent image carrier by the alternating electric field is t1. When the working time is t2, and the duty of the developing bias is t1 / (t1 + t2), and the frequency of the alternating electric field is f [Hz],

[0011]

(Equation 3)

It is characterized by the following.

According to a second aspect of the present invention, in the developing device according to the first aspect, the waveform of the alternating electric field is a rectangular wave.

According to a third aspect of the present invention, there is provided a developer carrying member arranged to face an electrostatic latent image carrying member carrying an electrostatic latent image, carrying a one-component developer, and the developer carrying member. And a bias applying means for applying a developing bias to the developing device. The developing device develops an electrostatic latent image on the electrostatic latent image carrier with a developer on the developer carrier. The alternating electric field, and the maximum potential when moving the developer on the developer carrier toward the electrostatic latent image carrier is Vma
x, the non-image portion potential of the electrostatic latent image is VD, the difference between VD and the Vmax is ΔV _D , the shortest distance between the electrostatic latent image carrier and the developer carrier is d [m], The average value of the charge per developer is Qm [C], and the time during which the force for moving the developer on the developer carrier toward the electrostatic latent image carrier by the alternating electric field is applied is t1. The time during which the force in the direction opposite to the direction in which the developer on the developer carrier is moved toward the electrostatic latent image carrier by the alternating electric field is applied is represented by t2.
And the duty of the developing bias is t1 / (t1 + t
2), the frequency of the alternating electric field is f [Hz]
Then

[0015]

(Equation 4)

That is,

According to a fourth aspect of the present invention, in the developing device according to the third aspect, the waveform of the alternating electric field is a rectangular wave.

According to a fifth aspect of the present invention, in the developing device according to the third aspect, the developer is non-magnetic.

According to a sixth aspect of the present invention, there is provided an image forming apparatus having a developing device for developing an electrostatic latent image on an electrostatic latent image carrier with a developer on a developer carrier. A developing device according to any one of Items 3 to 5.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to specific examples, but the present invention is not limited to these specific examples. As shown in FIG. 2, two flat plates 1 and 2 are separated by a distance d.
[M] and the voltage V
Consider a case in which a voltage V2 [V] is applied to the lower flat plate 2 by 1 [V]. A portion between the flat plates 1 and 2 has a uniform electric field. In this electric field, mass m [kg], charge q
The kinetic energy obtained when the toner 3 of [C] moves from the upper flat plate 1 to the lower flat plate 2 is represented by v, where the speed at which the toner 3 reaches the lower flat plate 2 is v.
It is shown by the following equation (1).

[0021]

(Equation 5)

According to the equation (1), the toner 3 is placed on the lower flat plate 2.
When the velocity v when the velocity reaches is obtained, the following equation (2) is obtained.

[0023]

(Equation 6)

If the charge per unit mass q / m of the toner 3 is defined as qm, the equation (2) can be transformed into the following equation (3).

[0025]

(Equation 7)

The movement of the toner 3 between the flat plates 1 and 2 is a uniform acceleration movement. When the velocity of the toner 3 is 0 when the toner 3 is carried on the upper flat plate 1, the acceleration a
If [m / s ² ], v ² = 2ad

[0027]

(Equation 8)

## EQU1 ##

The toner 3 is transferred from the upper flat plate 1 to the lower flat plate 2
The time t [sec] required to reach is obtained from the following equation (5). v = at

[0030]

(Equation 9)

The embodiment of the present invention is an application of the above idea.

One embodiment of the present invention is a developer carrying device which is arranged to face a photosensitive member as an electrostatic latent image carrier for carrying an electrostatic latent image and carries a one-component type developer (toner). An electronic device comprising: a developing sleeve as a body; and a bias applying means for applying a developing bias to the developing sleeve, and a developing device for developing an electrostatic latent image on the photoconductor with a developer on the developing sleeve. This is an embodiment of a photographic image forming apparatus.

In this image forming apparatus, the shortest distance (so-called developing gap) between the photosensitive member and the developing sleeve is d.
[M], and a rectangular wave developing bias as shown in FIG. 3 is applied to the developing sleeve from the bias applying means. This developing bias is a rectangular wave in which the maximum value Vmax and the minimum value Vmin are generated alternately, and the duration of Vmax is t1.
And the duration of Vmin is t2 and the duty (dut)
y) is t1 / (t1 + t2). The DC level of this developing bias is VDC, and in FIG.
S2 is S1 = S2.

The photosensitive member is charged to the voltage VD, and the potential of the image area on the photosensitive member is VL. When a developing bias of Vmax is applied to the developing sleeve, the potential of the non-image portion is
Assuming that the potential difference between VD and Vmax is ΔV, the time until the toner on the developing sleeve reaches the photoreceptor can be expressed by equation (5). Since the charge amount of the toner differs for each toner, qm
Means that the average particle diameter of the toner is r [m] and the specific gravity of the toner is ρ [k
g / m ³ ] and the average charge density per toner is qt [C /
kg]

[0035]

(Equation 10)

The average value Qm [c] of the charge per toner represented by

The frequency of the developing bias shown in FIG.
Z]

[0038]

[Equation 11]

## EQU1 ## In order for the toner not to move to the non-image portion, at least t1 needs to be smaller than t in Expression (5). Therefore, a desirable range of the frequency f is represented by the following equation (6).

[0040]

(Equation 12)

However, this is a case where air resistance is not considered.

Actually, since the toner is affected by air resistance, the time required for the toner to move to the non-image portion is later than the value represented by the equation (5). In order to consider the effect of air resistance on the toner, the present inventors bias the flat plates 1 and 2 and observe the flying state using charged particles. It has been confirmed that the time t [sec] required to reach the value does not become slower than twice the value of the expression (5). In many cases, t was about 1.4 times the value of equation (5). Therefore, the desirable range of the frequency f is as follows:
It is expressed by equation (7).

[0043]

(Equation 13)

More preferably,

[0045]

[Equation 14]

Next, consider the upper limit of the frequency f. Frequency f
When the value is increased, the toner attached to the non-image portion and the toner near the non-image portion vibrate more greatly, and the background smear is reduced. Regarding this result, Japanese Patent Publication No. Sho 63-30622 describes that there is no difference in the effect obtained when the frequency f is around 10 kHz, the power source becomes larger, and the merit is reduced. Therefore, the upper limit of the frequency f is preferably 10 kHz.

Therefore, a desirable range of the frequency f is as follows: When the difference between the non-image portion potentials VD and Vmax of the electrostatic latent image is ΔV _D ,

[0048]

(Equation 15)

More preferably,

[0050]

(Equation 16)

Is as follows.

Next, the present invention will be specifically described with reference to Examples and Comparative Examples. FIG. 1 schematically shows Embodiment 1 of the present invention. As the electrostatic latent image carrier that carries the electrostatic latent image, for example, a drum-shaped photoconductor 10 is used, but a belt-shaped photoconductor, a sheet-shaped photoconductor, or the like may be used. This photoconductor 1
0 is rotated clockwise by a drive unit (not shown), is uniformly charged by the charging device 20, is exposed by the exposure device 30, and forms an electrostatic latent image.

The developing device 40 is arranged to face the photoreceptor 10 and has a developing leave 40a as a developer carrying member for carrying a toner as a one-component developer, and applies a developing bias to the developing sleeve 40a. The electrostatic latent image on the photoconductor 10 is developed with toner on the developing sleeve 40a to form a toner image. The toner image on the photoreceptor 10 is transferred by transfer means (not shown) to transfer paper as a recording medium fed from a paper feeding device, and the toner image is fixed on the transfer paper on which the toner image has been transferred by a fixing device. Is discharged. Further, the photoconductor 10 is cleaned by a cleaning device (not shown) after the transfer of the toner image, and can be reused.

In Example 1, in order to evaluate the developed toner image on the photoconductor 10, the developed toner image on the photoconductor 10 was directly observed without using the transfer unit. By changing the frequency of the developing bias applied to the developing sleeve 40a from the bias applying unit and transferring the developed image on the photoreceptor 10 to a tape, and evaluating the background stain on the non-image portion, the following Table 1 was obtained. The result as shown in FIG.

[0055]

[Table 1]

Here, when the developing condition 1 of the first embodiment is substituted into the equation (6), f ≧ 978 Hz, and the developing condition 1 of the first embodiment is satisfied.
Is substituted into Expression (7), f ≧ 1369 Hz. Also,
The developing conditions 1 and the like are as follows. Development condition 1 Toner: Magnetic toner The charge amount is -2 μC / g. Photoreceptor: Organic photoreceptor Bright part potential -50 V Dark part potential -600 V Development bias: -450 V DC voltage is superimposed on a rectangular wave having a peak-to-peak value of 1600 V. And duty =
0.5, frequency 1.8 kHz Comparative Example 1 is different from Example 1 in that the frequency of the developing bias is 1.4 kHz. Comparative Example 2 is different from Example 1 in that the frequency of the developing bias was set to 800 Hz.

The rank of the above evaluation is 3: good 2: normal 1: bad.

Next, a second embodiment of the present invention will be described. In the second embodiment, the developing conditions in the first embodiment are changed to the following developing conditions. Developing condition 2 Toner: Magnetic toner The charge amount is 10 μC / g Photoconductor: Organic photoconductor Bright part potential −100 V Dark part potential −600 V Development bias: A superimposed DC voltage of −300 V on a rectangular wave having a peak-to-peak value of 1300 V. And duty =
0.5, frequency 1.6 kHz By substituting the developing condition 2 of Example 2 into the equation (6), f ≧ 10
When the developing condition 2 of the second embodiment is substituted into the equation (7), f ≧ 1414 Hz.

In the second embodiment, the photosensitive member 10
In order to evaluate the developed toner image above, the developed toner image on the photoconductor 10 was directly observed without using the transfer unit. The frequency of the developing bias applied from the bias applying means to the developing sleeve 40a is changed to
The developed image on No. 0 was transferred to a tape, and the non-image area was evaluated for background stain. The results shown in Table 2 below were obtained.

[0060]

[Table 2]

Comparative Example 3 is different from Example 2 in that the frequency of the developing bias was 1.2 kHz. Comparative Example 4 is different from Example 2 in that the frequency of the developing bias was set to 800 Hz.

The evaluation ranks in Table 2 are the same as described above.

As described above, according to the embodiment of the present invention, the electric field due to the developing bias is an alternating electric field, and the maximum electric field when the developer on the developer carrier 40a is moved toward the electrostatic latent image carrier 10 is maximized. The potential is Vmax, the potential of the non-image portion of the electrostatic latent image is VD,
The difference between VD and Vmax is ΔV, the shortest distance between the electrostatic latent image carrier 10 and the developer carrier 40a is d [m], and the developer 1
The average value of the charge per unit is Qm [C], and the developer on the developer carrier 40a is transferred to the electrostatic latent image carrier 1 by the alternating electric field.
The time during which the force for moving toward 0 is applied is t1, and the force in the direction opposite to the direction for moving the developer on the developer holding member 40a toward the electrostatic latent image holding member 10 by the alternating electric field is applied. Time t2, and the duty of the developing bias is t1 / (t1
+ T2), the frequency of the alternating electric field is f [H
z]

[0064]

[Equation 17]

Therefore, background dirt is reduced.

Further, according to the embodiment of the present invention, the waveform of the alternating electric field is a rectangular wave, and the background dirt is reduced. In another embodiment of the present invention, a non-magnetic one-component developer is used as a developer in the developing device of the above-described embodiment, so that it is possible to easily cope with colorization.

[0067]

As described above, according to the first and second aspects of the present invention, it is possible to provide a developing method with less background contamination. As described above, according to the third and fourth aspects of the present invention, it is possible to provide a developing device with less background contamination. According to the invention according to claim 5, it is possible to easily cope with colorization. According to the invention according to claim 6 as described above,
An image forming apparatus with less background dirt can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view schematically showing a first embodiment of the present invention.

FIG. 2 is a diagram illustrating an embodiment of the present invention.

FIG. 3 is a waveform chart showing an example of a developing bias.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Photoconductor 20 Charging device 30 Exposure device 40 Developing device 40a Developing sleeve

Claims (6)

[Claims] An electrostatic latent image carrier for carrying an electrostatic latent image;
A developer carrying member that carries a component-based developer,
A developing via is applied to the developer carrier by a bias applying means.
The electrostatic latent image on the electrostatic latent image carrier is
In the developing method of developing with a developer on the developer carrying member,
The electric field due to the developing bias is an alternating electric field,
The developer on the developer carrier is moved toward the electrostatic latent image carrier.
The maximum potential when moving is Vmax, the non-image part of the electrostatic latent image
The potential is VD, and the difference between VD and Vmax is ΔV _DAnd said
The shortest distance between the electrostatic latent image carrier and the developer carrier is d
[M], and the average value of the charge per developer is Qm
[C] developing on the developer carrier by the alternating electric field
When a force is applied to move the agent toward the electrostatic latent image carrier
The interval is t1, the current on the developer carrier is
The direction opposite to the direction in which the image agent is moved toward the electrostatic latent image carrier
The time during which the directional force is acting is t2, and the developing bias
When the duty of is t1 / (t1 + t2),
Assuming that the frequency of the electric field is f [Hz],A developing method, characterized in that: 2. The developing method according to claim 1, wherein said alternating electric field has a rectangular waveform. 3. A developer carrying member arranged to face an electrostatic latent image carrying member carrying an electrostatic latent image and carrying a one-component type developer, and a developing bias is applied to the developer carrying member. A bias applying means, and a developing device for developing the electrostatic latent image on the electrostatic latent image carrier with a developer on the developer carrier, wherein the electric field due to the developing bias is an alternating electric field, The maximum potential when moving the developer on the developer carrier toward the electrostatic latent image carrier is Vmax, the non-image portion potential of the electrostatic latent image is VD, and the difference between this VD and the Vmax is Δ
V _D , the shortest distance between the electrostatic latent image carrier and the developer carrier is d [m], the average value of the charge per developer is Qm [C], and the developer is obtained by the alternating electric field. The time during which the force for moving the developer on the carrier toward the electrostatic latent image carrier is working is t1, and the developer on the developer carrier is moved toward the electrostatic latent image carrier by the alternating electric field. When the time during which the force in the direction opposite to the moving direction is acting is t2 and the duty of the developing bias is t1 / (t1 + t2),
Assuming that the frequency of the alternating electric field is f [Hz], A developing device, characterized in that: 4. The developing device according to claim 3, wherein said alternating electric field has a rectangular waveform. 5. The developing device according to claim 3, wherein said developer is non-magnetic. 6. An image forming apparatus having a developing device for developing an electrostatic latent image on an electrostatic latent image carrier with a developer on a developer carrier, wherein the developing device is any one of claims 3 to 5. An image forming apparatus, comprising: the developing device according to claim 1.