JPH01114866A - Method and device for electrophotographic recording - Google Patents

Abstract

PURPOSE:To eliminate troubles such as increase in toner consumption and increase in cleaning difficulty by impressing a bias voltage in a time range including a period when developing carriers face the highly electrified potential part of a photosensitive body without lowering in non-printing mode a bias voltage scattering toner at the time of non-contact development instantaneously to zero. CONSTITUTION:A 1st electrifier 2 forming a 1st colored toner image, a first exposing system 3, a 1st developing unit 4, a 2nd electrostatic charger 5 forming a second colored toner image, a 2nd exposing system 6 and a 2nd developing unit 7 are arranged on the outer periphery of the photosensitive body 1 of a two-colored electrophotographic process. The developing unit 7 employs a non-contact system. Where the time span when the photosensitive body 1 passes by a point A facing the developing unit 7 in an electrified area is t1, and the 2nd time range when an unelectrified area passes by the point A is t2, a development bias impressing time t3 is calculated and taken for a prescribed value. Carrier scattering can be prevented when no development is performed.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to electrophotographic recording technology, and more particularly.

The present invention relates to a recording method and a recording device suitable for application to color printers and color copying machines that use cut paper.

[Conventional technology]

2. Description of the Related Art Recently, in electrophotographic color printers, a technology is being developed that uses non-contact development to prevent color mixing and image distortion. In non-contact development, a thin layer of toner or a thin layer of two-component developer consisting of toner and carrier is formed on a developer carrier, and a bias voltage is applied to cause the toner to fly to a photosensitive drum. This type of device is broadly divided into (a) a toner single layer method in which the thin layer on the developer carrier is made of toner alone, and (b) a two-component thin layer method in which the thin layer on the developer carrier is formed from a mixture of toner and carrier. be done. The toner single layer method is a method for applying toner to the developing roll, (a) a method in which a magnetic brush roll is installed separately and the application is performed using the magnetic brush;
(b) A method has been devised in which the application is applied by pressing an elastic blade, but the former (magnetic brush) requires a larger developing machine;
The latter (elastic blade) has the drawback of poor stability due to toner adhesion to the developing roll. On the other hand,
The two-component thin layer method has the advantage of relatively simplifying the structure of the developing machine and avoiding increasing its size, but there is a risk that the carrier will fly to the photoreceptor along with the toner during development or non-development. No. 60-242469 proposes a method of using an insulating carrier to prevent the carrier from flying during development.

[Problem that the invention seeks to solve]

The above-mentioned known technique (Japanese Unexamined Patent Publication No. 60-242469) has the following problems.

That is, in FIG. 4, Vp^ is the surface potential of the photoreceptor portion facing the non-contact developing device, Vo is the charging potential of the photoreceptor, and ■
, is the residual potential after exposure, t is the elapsed time, and Va is the bias voltage applied to the developer carrier 6 In addition, in non-contact development where a DC voltage is applied, the bias voltage Va is:
It is set to a value that is equal to or slightly lower than the charging potential Vo.

Further, the area where the photoreceptor is charged needs to cover the printing area of the cut paper, so it is a little larger than the printing area. Therefore, the time required to operate the charger and perform charging is slightly longer than the time it takes for the portion of the cut paper corresponding to the printing area to pass through the developing section (referred to as print mode). 21 with parallel diagonal lines indicates a portion where the charging time is longer than that in the print mode.

In the print mode, there is an exposure system 0N-O based on the print signal.
A charge latent image is formed along with the FF.

Reference numeral 18 represents the surface potential of the unexposed area, and numeral 17 represents the surface potential of the exposed area.Non-contact development was performed by applying a bias voltage corresponding to the printing mode to develop such a latent charge image. but,
During non-development, when the bias voltage is turned off corresponding to the non-printing mode, the charging voltage and developer carrier are During this time, an electric field acts during development and in the moving direction. The conventional technology does not take this point into consideration, and there is a problem in that carriers fly to the photoreceptor due to the electric field in the opposite direction.

Also, if you continue to apply bias voltage in non-printing mode,
There is also the problem that toner adheres to unnecessary portions, increasing toner consumption and making it difficult to clean the photoreceptor. Therefore, the bias voltage application time cannot be increased indefinitely.

The present invention has been made in view of the above-mentioned circumstances, and when color printing is performed on cut paper using non-contact development technology, there is no need to worry about increasing toner consumption or inducing difficulty in cleaning the photoreceptor. It is an object of the present invention to provide a recording method and apparatus capable of preventing carrier flying during development.

[Means for solving problems]

Next, the basic principle of the present invention will be described.

The purpose of the above is to reduce the bias voltage that causes toner to fly during non-contact development without immediately dropping to zero during non-printing mode, and to reduce the bias voltage in the time range that includes the time when the developer carrier faces the highly charged area of the photoreceptor. This is achieved by applying .

However, in the present invention, time ta includes time 11 means that time ta is time t! This means that the time to starts earlier than the time t1, and the time to ends later than the time t1.

Based on the above principle, and as a specific configuration for applying the same to a practical aspect, the method of the present invention develops a latent charge image on a photoreceptor with a developing machine to form a visible image of toner, The electrophotographic recording method for transferring the above-mentioned toner image onto cut paper is applied, and (i) a gap is formed between the two-component developer layer formed on the developer carrier and the photoreceptor. While performing non-contact development, (ii) applying a bias voltage to the developer carrier during the period when the developer carrier faces the area including the charged area of the photoreceptor, during non-development time; This prevents the carrier from flying away.

In addition, the apparatus of the present invention created to carry out the above-mentioned method of the present invention has the following features: (i) A gap is formed between the two-component developer layer formed on the developer carrier and the photoconductor to prevent contact. A non-contact developing machine is provided to perform development, and (ii) voltage control is applied to apply a bias voltage to the developer carrier during a period when the developer carrier faces the area including the charged area of the photoreceptor. This means that a means has been established.

[Effect]

According to the above method, since a two-component thin layer system of toner and carrier is adopted for forming a thin developer layer, the structure is simple and suitable for miniaturization, and the height of the developer carrier and photoreceptor is high. A bias voltage is always applied to the developer carrier while it faces the potential charging section, so the bias voltage is turned off.
Even with F, no electric field is generated in the opposite direction to that during development. Therefore, carriers do not fly during non-development (bias voltage FF).

Further, in the apparatus of the present invention having the above-mentioned configuration, the structural members necessary and sufficient for carrying out the above-described method of the invention are appropriately arranged, so that the method of the invention can be carried out easily and reliably.

〔Example〕

Next, an example of implementing the method according to the present invention using the apparatus according to the present invention will be described with reference to FIGS. 1 to 3.

FIG. 1 shows an embodiment in which the present invention is applied to a two-color electrophotographic process. In FIG. 1, a first charger 2. First exposure system 3. a first developing device 4; and a second charger 5 for creating a second color toner image. Second exposure system 6
．． A second developing machine 7 is arranged. The second developing machine 7 is
A non-contact developing system is used to prevent the colored toner image from being scraped off (the configuration of the non-contact developing machine will be described later with reference to FIG. 3). Two-color toner images are created on the photoreceptor 1 by this non-contact developing device, and then fed from the paper feed cassette 15.

The toner image is transferred onto the cut paper by the transfer device 11, and then the toner image is transferred to the cut paper by the fixing device 1.
In step 6, the toner image is thermally melted and fixed to the cut paper to create a permanent image. Further, 12 is a peeling claw for peeling the cut paper from the photoreceptor 1 during transfer, 13 is a cleaner for removing toner remaining on the photoreceptor 1, and 14 is for setting the surface potential of the photoreceptor 1 to a predetermined initial value. This is a static eliminator 14 for. A second charger relay 8. A second current machine relay 9 is connected, and the ON-OFF timing of the above-mentioned relay 8.9 is controlled by the sequencer 1o.

Details of the second developing device 4 are shown in FIG. A two-component developer, which is a mixture of carrier 19 and toner 20, is used as the developer. The developer carrier is constituted by a developing sleeve 23 rotatably disposed around the outer periphery of the magnet roll 22 . A gap (the gap length is indicated by δl) is provided between the developer layer (its maximum thickness is indicated by 62) at the portion where the developing sleeve 23 faces the photoconductor 1 and the photoconductor 1, so that a non-contact state is established. A voltage is applied that has the same charging polarity as the toner 20 and is equal to or slightly lower than the charging potential Vo of the photoreceptor 1, and only the toner 20 is caused to fly onto the photoreceptor 1 for development. 27 is a toner supply roller, 28 is a toner hopper, 2
5 is a scraper, and 26 is a stirring means.

In the present invention, in such a configuration, as shown in FIG. 2, the time range in which the charged area of the photoreceptor 1 passes through point A facing the non-contact developing device 7 is defined as a first time range 1, and the uncharged area is defined as 1. Assuming that the time range in which the image data passes through point A is defined as the first time range t2, the developing bias application time ta is controlled by the sequencer 10 so that it satisfies the following equation (1).

In equation (1), Δt is preferably as small as possible.

This is because the amount of adhered toner increases, the amount of toner consumed increases, and cleaning of the photoreceptor 1 becomes burdensome.

In such a configuration, during non-development, that is, when the bias voltage is turned off, the surface potential Vp^ of the photoreceptor 1 is always a low value, and an electric field in the opposite direction to that during development is not generated in the development area. . Therefore, even if non-contact development is performed using a two-component developer, the carrier 19 will not fly to the photoreceptor 1 during non-development. Also, in equation (1), Δt
By setting as small as possible, it is possible to reduce the amount of toner adhering to the non-printing area of the photoreceptor.

〔Effect of the invention〕

As explained above, when the method of the present invention is applied, even if development is performed using a two-component thin layer type non-contact development in a color electrophotographic device using cut paper, toner will be wasted and the photoreceptor will be damaged. The carrier can be prevented from flying away without causing cleaning difficulties.

Moreover, according to the apparatus of the present invention, the above-described method of the invention can be carried out easily and reliably, and the effects of the method of the invention can be fully exhibited.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of one embodiment of the present invention, and FIG. 2 is a graph showing the time variation of the surface potential of the photoreceptor and the bias voltage applied to the developer carrier when the present invention is applied to the developing section. Explanatory diagram, FIG. 3 is a partial sectional view of one embodiment of the present invention, and FIG.
The figure is an explanatory chart of temporal changes in the surface potential of a photoreceptor and the bias voltage applied to a developer carrier in a conventional developing section. DESCRIPTION OF SYMBOLS 1... Photoreceptor, 2... First charger, 3... First exposure system, 4... First developing device, 5... Second charger, 6...
...Second exposure system, 7...Second developer, 8...Second charger relay, 9...Second developer relay, 10...Sequencer, 11...Transfer device, 12 ... Peeling, 1
3...Cleaner. 14... Static eliminator, 15... Paper feed cassette, 16...
-Fixing device, 17...Surface potential of exposed area, 18...Surface potential of non-exposed area, 19...Carrier, 2o...Toner, 21...Charged area that causes reverse electric field, 2
2... Magnet roll, 23... Developing sleeve,
24...Regulation plate, 25...Scraper, 26...
Stirring means, 27... Toner supply roller, 28... Toner hopper, Vc... Second charger power supply voltage, Va.
... Bias voltage of the second developing machine of non-contact developing method, Vp
^...Surface potential of the photoreceptor portion facing the non-contact developing device, Vo...Charging potential of the photoreceptor, Vr...Residual potential after exposure, t...Elapsed time. tl...time for the charged area to pass through the non-contact developing section;
t2... Time for the uncharged area to pass through the non-contact developing section,
tB: Development bias application time, Δt: Development bias application time tolerance.

Claims (1)

[Scope of Claims] 1. In an electrophotographic recording method in which a charge latent image on a photoreceptor is developed with a developing machine to form a visible toner image, and the toner image is transferred to cut paper, ) Non-contact development is performed by forming a gap between the two-component developer layer formed on the developer carrier and the photoconductor, and (ii) the developer carrier is located in the charged area of the photoconductor. 1. An electrophotographic recording method, characterized in that a bias voltage is applied to the developer carrier during a period when the developer carrier is facing a region including the carrier, thereby preventing the carrier from flying away during non-development. 2. In an electrophotographic recording device in which a charge latent image on a photoreceptor is developed with a developing machine to form a visible toner image, and the toner image is transferred to cut paper, (i) on a developer carrier; (ii) a non-contact developing machine is provided which performs non-contact development by forming a gap between the two-component developer layer formed on the photoreceptor and the photoreceptor; 1. An electrophotographic recording apparatus, comprising a voltage control means for applying a bias voltage to the developer carrier during a period when the developer carrier faces a region including the developer carrier. 3. There are a plurality of developer carriers, and the plurality of developer carriers are arranged so as to face one photoreceptor, and one of the photoreceptors is arranged for each developer carrier. An electrophotographic recording according to claim 2, characterized in that a voltage control means is provided for applying a bias voltage to the developer carrier during a period when the developer carrier faces an area including a charged area. Device.