JPH0455881A - Image forming device - Google Patents

Abstract

PURPOSE:To remove residual developer on an electrostatic latent image carrier to such an extent that there is no trouble in practical use by connecting a voltage impressing means to a developing device, an electrostatic charging member and a collecting member. CONSTITUTION:An electrostatic charging device is provided with the electrostatic charging member 8 which contacts with an image carrier 1 and the collecting member 7 which faces the electrostatic charging member, and the voltage impressing means is connected to the developing device 3, the member 8 and the member 7. At the time of forming an image, an electrostatic latent image is developed by the device 3 and the image carrier 1 is electrostatically charged by the member 8, then the developer remaining on the image carrier 1 after transfer is removed and the removed developer is collected and held by the member 7. At the same time of not forming the image, the impressed voltage is controlled so that the developer on the member 7 may be collected in the device 3 through the member 8 and the image carrier 1. Thus, the residual developer on the electrostatic latent image carrier 1 is removed to such an extent that there is not trouble in practical use and can be utilized again.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image forming apparatus such as an electrophotographic copying machine or printer.

[Conventional technology]

According to an image forming apparatus such as an electrophotographic copying machine or printer, image formation is performed as follows.

That is, an electrostatic latent image carrier whose surface is charged with a negative potential by a charging means is exposed to an image corresponding to the image to be copied or printed, thereby forming an image on the image carrier. The electrostatic latent image is developed into a visible image by a developing device, and this visible image is transferred onto a transfer material and fixed.

In this case, all the developer on the electrostatic latent image carrier is not transferred to the transfer material, and the transfer efficiency is usually 80 to 90%.
Approximately 10 to 20% of the developer remains without being transferred. This residual developer is generally removed by a cleaning device.

As the above-mentioned cleaning device, there are known those of the web-sliding type, the fur brush type, the roller type, and the flade type.

[Problem to be solved by the invention]

However, the conventional cleaning device has the following problems.

- The existence of a cleaning device limits the ability to make image forming apparatuses smaller and cheaper.

(2) When the removed developer is discarded, there is a large loss of the developer, and when it is to be reused, a separate means must be added to return it to the developing device.

■ Whether the removed developer is disposed of or returned to the developing device, a container to temporarily collect the removed developer and a space for its installation are required, which increases the size of the image forming device (Japanese Patent Application Laid-Open No. 1983-1999). 143477).

■ To avoid increasing the size of the device, or to avoid increasing the size of disposable cleaning devices,
When the collection container is made smaller, the actual amount of residual developer increases, especially when an image with low developer consumption (an image with little coloring due to developer) is formed, so the collection container becomes full after a short period of use. This will cause developer to spill.

Therefore, in the present invention, an electrostatic latent image bearing member is charged by a charging device, and then imagewise exposed to form an electrostatic latent image on the image bearing member, and the latent image is developed by a developing device to make it visible. In an image forming apparatus that transfers the visible image to a transfer material, the conventional cleaning device is omitted, and the conventional problems caused by the cleaning device are eliminated, and the residual image on the electrostatic latent image carrier is eliminated. The purpose is to remove developer to a practically acceptable level so that it can be reused.

[Means to solve the problem]

In accordance with the above-mentioned object, the present invention charges an electrostatic latent image carrier with a charging device, and then exposes it to imagewise light to form an electrostatic latent image on the image carrier, and develops the latent image with a developing device. In the image forming apparatus that generates a visual image and transfers the visible image to a transfer material, the charging device includes a charging member that contacts the image carrier and a collection member that faces the charging member, and the charging device includes the developing device and the A voltage applying means is connected to the charging member and the collection member, and the voltage applying means is configured to cause the developing device to develop the electrostatic latent image and the charging member to charge the image carrier during image formation. At the same time, the developer remaining on the image carrier after the transfer is removed, and the collection member collects and holds the removed developer, and when an image is not formed, the developer on the collection member is transferred to the charging member and the developer. The present invention provides an image forming apparatus characterized in that the applied voltage can be controlled so that the image is recovered to the developing device via the image carrier.

[For production]

According to the apparatus of the present invention, during image formation, the electrostatic latent image bearing member is uniformly charged by the charging member of the charging device and then imagewise exposed to form an electrostatic latent image.

This latent image is developed by a developing device to become a visible image, and this visible image is transferred to a transfer material and fixed.

After the transfer, the developer remaining on the electrostatic latent image carrier is scraped off and retained by the charging member that is charging,
Subsequently, it is transferred from the charging member to a collecting member, where it is held.

On the other hand, during non-image formation, the developer on the collection member is transferred onto the charging member by controlling the voltage applied to each part, from there it is deposited on the electrostatic latent image carrier, and from there it is collected into the developing device. can.

〔Example〕

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

FIG. 1 shows a schematic configuration of a printer as an embodiment.

This printer is equipped with a photosensitive drum 1 that is driven to rotate clockwise in the figure, and around the drum there is a developing device 3,
Conductive fur brush 8 which is a rotating contact type charging member
and a transfer charger 6. fur brush 8
has a volume resistivity of 10 2 to 10 bΩcm, contacts the surface of the photosensitive drum 1, and is rotated clockwise in the figure. A collection roller 7, which is a collection member, is in contact with the fur brush 8, and this roller is also rotated clockwise in the figure.

In addition, in the figure, 5 is a pair of paper guide rollers.

The developing device 3 includes a developing sleeve 31 that is rotated counterclockwise in the figure, and the sleeve collects the positively charged toner T housed in the casing 32 in an adhering amount of 0.6 cm/cI.
M, a uniform toner layer adjusted to a charge amount of 20 μc/g is transported to the development area.

As shown in FIG. 2, a voltage application device 9 is connected to the developing sleeve 31, the fur brush 8, and the collection roller rough. This device 9 includes a power supply Vbl (-200V) and a power supply Vb2 (-400V) connected to the developing sleeve 31 via a power supply switching section 91, and a power supply Vc connected to the fur brush 8 via a power supply switching section 92. , (IKV) and Vc2 (+500V), the power supply switching unit 9 is connected to the collection roller rough.
The control section 94 includes a power supply Vr+ (1.5 KV) and a power supply V rz (+900 V) connected through the power supply terminal 3, and a control section 94 that switches and controls the power supply switching sections 91, 92 and 93.

According to the printer described above, when forming an image, the second
As shown in the figure, the control unit 94 in the voltage application device 9 connects the developing sleeve 31 to the power source 2b1, the fur brush 8 to the power source Vc, and the collection roller rough to the power source Vr.

With the bias voltage being applied to each part in this manner, the photosensitive drum 1, fur brush 8, and collection roller 7 are each driven to rotate clockwise in the figure, and the developing sleeve 31 is driven to rotate counterclockwise. .

The photosensitive drum 1 has a uniform surface potential V by the fur brush 8 to which a voltage of Vc,=-IKV is applied.

It is charged to about -600v. The surface of the photoreceptor drum 1 charged in this way is subjected to image exposure 2 from an exposure device (not shown),
The potential of the exposed area decreases depending on the amount of light, thus forming an electrostatic latent image.

This electrostatic latent image has a developing bias voltage Vb of −−200■
is developed and visualized by the toner T on the developing sleeve 31 to which is applied. This visible image is transferred to a transfer paper 4 supplied from a transfer paper supply device (not shown) by a transfer charger 6.
After being transferred, the image is fixed onto the paper by a fixing device (not shown).

After the transfer, residual toner remaining on the photoreceptor drum 1 reaches the fur brush 8 as the drum 1 rotates, and is scraped off from the surface of the drum 1 by the fur brush 8 while being electrically connected to the brush. is attracted to. At the same time, the brush 8 uniformly covers the surface of the drum 1 with a surface potential Vo of about -600.
■It becomes electrically charged. The residual toner T attracted by the fur brush 8 is electrically attracted onto the recovery roller 7 to which a recovery bias voltage of Vr,=-1.5 KV is applied, and is held on the roller. In this way, image formation is performed, and the toner T remaining on the photosensitive drum 1 after transfer is held on the collection roller 7 via the fur brush 8, and does not fall off or scatter around. Further, since the residual toner T is retained by the roller rough, appropriate charging and exposure can be performed without being affected by the residual toner during image formation.

Next, the operation during non-image formation will be explained. During non-image formation, as shown in FIG. 3, the control unit 94 in the voltage application device 9 switches the power supply switching units to supply the power supply vb2 to the developing sleeve 31 and the power supply Vcz to the fur brush 8.
and a power supply Vrz is connected to the collection roller rough.

In this way, the developer held on the recovery sleeve 7 is applied to the recovery roller by a bias voltage V r z −+ 900
(2) is applied and the voltage Vc2- is applied to the fur brush 8.
By applying +500V, the particles are transferred from the collection roller 7 to the fur brush 8 while being scraped by the fur brush 8, and subsequently adhered to the photoreceptor drum 1. The toner T deposited on the photoreceptor drum 1 has a bias voltage of Vb2--4.
00V is applied to the developing sleeve 31, and is collected into the developing device 3.

In addition, FIG. 4 shows the control unit 9 when printing two sheets continuously.
4 shows the switching timing of each bias.

As can be seen from this timing chart, the power supplies Vb2, Vcz and Vr2 are used, and power supplies Vbl and Vc+ are used during image formation.
and Vr.

is used.

According to the printer described above, when removing the residual toner T from the photoreceptor drum 1, there is no need for a conventional cleaning device or a container to temporarily collect the removed developer, so the printer can be made smaller and lower in price. can be realized.

Further, the residual toner T on the photosensitive drum 1 is only temporarily held by the collection roller 7 during image formation, and is returned to the developing device 3 again when no image is formed. There is no fear that the toner 7 will become full and spill, and furthermore, the remaining toner T can be collected into the developing device 3 and reused.

〔Effect of the invention〕

As explained above, according to the present invention, an electrostatic latent image bearing member is charged by a charging device, and then imagewise exposed to form an electrostatic latent image on the image bearing member, and the latent image is developed by a developing device. In an image forming apparatus that generates a visible image and transfers the visible image to a transfer material, problems that often occur when using the cleaning device instead of a conventional cleaning device are solved, and the problem is solved. The residual developer on the latent image carrier can be removed to a practically acceptable extent, and there is no fear of it spilling out, and it can be reused.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of a part of an embodiment of the present invention, FIG. 2 is an explanatory diagram showing the state of voltage application to each part by the voltage application device and the state of transfer of residual toner during image formation, and FIG. 3 4 is a similar explanatory diagram at the time of non-image formation, and FIG. 4 is a timing chart showing a bias power supply switching state based on an instruction from a control section in the voltage application device. 1... Photosensitive drum 3... Developing device 4... Paper 8... Charging fur brush 7... Collection roller 9... Voltage application device 91, 92, 93... Power switching unit 94... Control unit vb, , vb2... Power supply Vc, , Vcz... Power supply Vrl, Vrz... Power supply connected to the collection roller Applicant Minolta Camera Co., Ltd. Figure 4 l... Light emitting body Drum 3...Developing device 4...Paper 8...Charging far plane 7...Recovery roller 9...Voltage application device 91, 92, 93...Power switching unit 94...Control unit Vb, Vbz Vcl, VC2 Vr+, Vrz...Power supply...Power supply...Power supply connected to the collection roller

Claims (1)

[Claims] (1) After charging the electrostatic latent image carrier with a charging device, image exposure is performed to form an electrostatic latent image on the image carrier, and the latent image is developed with a developing device to become a visible image; In the image forming apparatus that transfers the visible image to a transfer material, the charging device includes a charging member that contacts the image carrier and a collection member that faces the charging member, and the charging device includes a charging member that contacts the image carrier and a collection member that faces the charging member, and the charging device includes a charging member that contacts the image carrier and a collection member that faces the charging member. A voltage applying means is connected to the member, and when forming an image, the developing device develops the electrostatic latent image, the charging member charges the image carrier, and the voltage applying means controls the transfer. Afterwards, the developer remaining on the image carrier is removed, and the collection member collects and holds the removed developer, and when an image is not formed, the developer on the collection member is transferred to the charging member and the image carrier. An image forming apparatus characterized in that an applied voltage can be controlled such that the applied voltage is collected to the developing device via.