JPS6352165A - Electrostatic latent image developing device - Google Patents

Abstract

PURPOSE:To easily control the electrified polarity and electrified quantity of toner, by injecting electric charges into toner passed through the contacting section of a conductive thin-plate electrode and resistance layer through the electrode contacting with the resistance layer having prescribed volume resistivity on the surface of a developing agent carrying section. CONSTITUTION:Thickness of a toner layer 8 formed on the surface of a developing roll 5 constituted of a conductive layer 4 and resistance layer 3 formed on the surface of the layer 4 is adjusted by means of the pushing force of a conductive thin-plate electrode 6 to the developing roll 5. When the volume resistivity of the resistance layer 3 is set at 10<6>-10<12>OMEGAcm, no accumulation of electric charges is provided on the surface of the resistance layer 3 even if a bias voltage is applied from a power source 7 through the electrode 6. Therefore, the electrification leading characteristic of the toner on the developing roll 5 is improved and the charged polarity and charged quantity of the toner can easily be controlled.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an electrostatic latent image developing device, and more specifically, it relates to an electrostatic latent image developing device, and more specifically, it relates to an electrostatic latent image developing device, and more specifically, a device for developing an electrostatic latent image on a photoreceptor or electrostatic recording paper in electrophotography, electrostatic recording, etc. The present invention relates to a device for developing an electrostatic latent image formed on a surface using a single-component toner.

[Conventional technology]

As a device for developing an electrostatic latent image formed on a photoreceptor in electrophotography or on an electrostatic recording paper in electrostatic recording method with a single-component toner, JP-A No. A layer of toner is formed on the resistance layer on the surface of the developing roll while pressing a blade made of a conductive thin metal plate or a rubber plate onto a developing roll provided with a resistance layer of Ω・1 or less, and at the same time, a voltage is applied to the conductive blade. A developing method is disclosed in which a predetermined amount of charge is imparted to a developing roll by applying , and reversal development can be performed by changing the charge polarity of the toner. However, in such a developing method, when forming a thin toner layer with a thickness of 25 to 30 μm, it is necessary to increase the pressing force of the conductive blade against the surface resistance layer of the developing roll, and as a result, the conductive blade There is a drawback that leakage occurs due to the bias flowing from the blade through the thin toner layer on the surface of the developing roll. Further, under the conductive plate pressing conditions that do not cause such bias current leakage, the desired three toner layers cannot be formed on the surface of the developing roll.

[Problem that the invention seeks to solve]

The present invention aims to provide a developing device that eliminates the drawbacks of the prior art as described above, which prevents bias current leakage and does not adversely affect development. In this way, the surface resistance layer of the developing roll is selected to improve the charge rise characteristics of the toner on the developing roll, to control the charge polarity and amount of charge of the toner on the developing roll, and to enable the ambipolar phenomenon. It is something.

[Means and effects for solving the problem] According to the present invention, the above problem can be solved by providing a resistive layer with a volume resistivity of 106 to 10'2 Ω on the surface of the developing roll as a developer conveying member. A conductive thin plate electrode is provided on the outside of the developer conveying member so as to be able to contact the resistance layer on the surface thereof, and the toner adhering to the developing roll and passing between the resistance layer and the conductive thin plate electrode is This problem is solved by a developing device that injects and applies charges via a three-plate electric scraper.

The developing device according to the present invention will be explained with reference to FIG.
is a hopper containing the toner 2, and the developing roll 5 is composed of a conductive layer 4 and a resistor N3 provided on its surface. The thickness of the toner layer 8 formed on the surface of the developing roll is controlled by adjusting the pressing force of the conductive thin plate electrode 6 against the developing roll. Reference numeral 7 denotes a charge injection bias power source for injecting charges into the toner via a conductive thin plate electrode. According to the present invention, if the volume resistivity of the resistive layer provided on the surface of the developing roll is less than 10''Ω·4, current leakage occurs when a bias voltage is applied, which is not preferable.

Furthermore, if the resistance exceeds 10 days Ω・inertia, charges are accumulated in the resistive layer, creating a potential difference with respect to the conductive layer of the developing roll, which acts as a developing bias effect during development, thus preventing the accumulation of such charges. This is disadvantageous because it requires a static elimination mechanism. Therefore, the volume resistivity of the resistive layer is 106 to 106Ω・
Cl11, preferably 10' to 10 Ω·country,
In the case of such a resistivity, no charge is accumulated on the surface of the resistive layer even if a bias voltage is applied through the conductive thin plate electrode.An example of a material having such a volume resistivity is Altos. ) A thin plate, a sheet in which conductive metal powder is dispersed in a synthetic resin to form an electric path in the thickness direction (for example, Bicon (trade name), Kureha Chemical), and the like. As the conductive thin plate electrode for controlling the thickness of the toner layer, an elastic material whose hardness is selected so as to be in surface contact with the toner layer and to be able to press uniformly in the axial direction of the developing roll, such as carbon-containing polyurethane or tan rubber, is suitable. ing. The toner used in the developing device of the present invention is not particularly limited, and both magnetic and non-magnetic toners can be used. However, when performing ambibolar development, it is preferable to use a toner that is located close to the material of the resistive layer in the triboelectric series; In order to improve the rise characteristics during development and to control the toner charge amount, it is desirable to fully consider the triboelectric series relationship with the material of the resistive layer. Must be careful. In this case, the thickness of the toner layer is 5~
100μ is preferable.

- In the single-layer shell development method, charge is applied to the toner by tribocharging, corona charging, electrostatic induction, etc. However, tribocharging is highly dependent on the environment, and corona charging is caused by toner tarowing, corotron wire Electrostatic induction has the disadvantage of causing problems in the transfer process at high temperatures.

In the present invention, since charge is injected into the toner using a conductive thin plate electrode, the charge rise characteristics of the toner during development are improved, the saturation charge amount of the toner can be controlled, and the toner is stable even in high temperature environments. It is possible to prevent a decrease in

The present invention will be explained in more detail with reference to the following examples and comparative examples.

Example 1 Using the developing device shown in Fig. 1, a static latent image on a photoreceptor was developed under the following conditions; Toner used: Nee component: Non-magnetic toner (>106Ω・Cl11) Conductive thin plate electrode: Carbon Contains polyurethane rubber (5X
10' Ω, thickness 2 fi) Resistance layer: Alumite (6xlO++ Ω, thickness 30μ)
) Developing roll surface speed: 127/sec Bias voltage: 400 V The change over time in the amount of charge of the toner on the developing roll (obtained from the value of the current flowing into the developing roll) is shown by the curve in Figure 2. Become. The amount of toner conveyed on the developing roll was approximately 0.2 .mu./-.

Comparative Example Developing was carried out under the same operating conditions as in Example 1, except that the bias voltage was set to 0, and the change in the amount of charge of the toner on the developing roll over time was measured, and curve B in FIG. 2 was obtained.

Comparing curve A (Example 1) and curve BB (comparative example) in Figure 2, it is found that when a bias voltage is applied to the conductive thin plate, the toner quickly reaches saturation charging, and the rise characteristics of toner charging are sharp. I know it will get better. Also, Example 1
(Curve A) shows that the occurrence of bias current leakage is prevented.

Example 2 The polarity of the bias voltage was changed, and the latent image was developed using the same equipment and operating conditions as in Example 1.
The amount of toner charge after 2 seconds was measured (by suction method) and the results are shown in Table 1.

Table 1 500 + 0.169 +29500 0.
227- shows that the toner charging polarity can be controlled by the polarity of the bias voltage. Further, no leakage of bias current occurred.

〔Effect of the invention〕

According to the developing device of the present invention, the charging rise characteristics of the toner on the developing roll are significantly improved, the charging polarity and the amount of charging of the toner on the developing roll can be easily controlled, and bias current leakage is prevented. A thin layer of toner can be formed on the developing roll without causing any problems.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the developing device of the present invention, Figure 2 is Embodiment 1
3 is a graph showing changes over time in toner charge amount in Comparative Examples. Codes in the diagram: 1... Hoff bar, 2... Toner, 3...
・Resistance layer, 4...R electric layer, 5...Developing roll, 6.
... Conductive thin plate electric scraper, 7... Power supply for bias, 8...
・Toner layer. 1st, Zusaki T(su)

Claims (1)

[Claims] A developer transporting member provided with a resistance layer on its surface having a volume resistivity of 10^6 to 10^1^2 Ωcm, and a developer transporting member provided outside the developer transporting member so as to be able to come into contact with the resistance layer on the surface thereof. The present invention is characterized in that it has a conductive thin plate electrode, and charges are injected into the toner that adheres to the developer transporting member and passes between the resistive layer and the conductive thin plate electrode through the thin plate electrode. Electrostatic latent image developing device.