JP2673581B2 - Image forming device - Google Patents

Description

The present invention relates to an image forming apparatus for forming an image by electrostatically adhering a developer onto a recording medium.

<Prior Art> Today, various apparatuses for forming an image according to image information have been developed. Among them, a conductive magnetic toner which is a fine powder developer is used to electrostatically transfer the toner to a recording medium. There is an image forming apparatus that adheres to form an image.

For example, a method disclosed in Japanese Patent Publication No. 51-46707 has been proposed. That is, in FIG. 4, the conductive magnetic toner 51 is conveyed along the outer periphery of the non-magnetic cylinder 50 by the magnetic field of the rotating magnet 52 provided coaxially with the non-magnetic cylinder 50. At that time, a voltage corresponding to image information is applied from the recording control unit to the recording electrodes 53 densely arranged along the axial direction on the outer peripheral surface of the non-magnetic cylinder 50. At this time, by applying the voltage between the conductive layer 54b and the conductive layer 54b of the recording medium 54 formed by laminating the conductive layer 54b and the insulating layer 54a from the back surface side provided in the vicinity of the non-magnetic cylinder 50, insulation is achieved. The toner 51 is attached to the layer 54a to form an image.

Further, as an image forming apparatus to which the above image forming method is applied, as shown in FIG. 5, the toner 57 is conveyed onto the recording electrode 56 by the rotation of the magnet roller 55 and is conveyed to a position facing the recording electrode 56. An image is formed on the recording medium 54 with or without the toner 57 depending on the signal from the recording electrode 56.

For example, when the signal voltage from the recording control unit 58 is + 40V, the toner 57 adheres to the recording medium 54 and does not adhere when the voltage is 0V.

The toner 57 adhering to the recording medium 54 is peeled off by the cleaning member 60 after the image is displayed on the image display section 59 and dropped onto the magnet roller 55 to be conveyed for the next recording.

The charge on the recording medium 54 is erased by applying a reverse polarity bias voltage to the cleaning member 60 from the charge removal power source 61.

<Problems to be Solved by the Invention> However, in the above-described conventional technique, the conveyance of the recording medium 54 must be temporarily stopped while displaying an image for one screen on the image display unit 59.

Even in this stopped state, a bias voltage is applied to the cleaning member 60 from the static elimination power source 61 and the recording medium
Reverse polarity charge is injected into 54.

As the display time of the image becomes longer, the contact time between the recording medium 54 and the cleaning member 60 at the same location becomes longer, so that the amount of charges injected into the recording medium 54 increases.

Then, when the recording medium 54 that has been temporarily stopped is conveyed, when the portion of the recording medium 54 that was previously in contact with the cleaning member 60 rubs against the toner 57 on the recording electrode 56,
Even if the signal voltage from the recording control unit 58 is 0V, the static elimination power supply
The charge injected from 61 sometimes adhered the toner 57 and soiled the recording medium 54.

When the recording medium 54 is in a stopped state,
When the pinhole on the surface of 54 is in contact with the cleaning member 61, a voltage is applied to the conductive layer 54b of the recording medium 54, the amount of charge injected into the recording medium 54 increases, and extra toner 57 adheres to the entire surface of the recording medium 54. There was a risk that it would get dirty.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art and provides an image forming apparatus capable of applying a bias voltage of reverse polarity to a cleaning member only when a recording medium moves.

<Means for Solving the Problems> In the configuration according to the present invention for solving the above problems, a recording electrode is provided so as to face a recording medium conveyed by a conveying means, and a conductive material is provided between the recording electrode and the recording medium. An image forming apparatus for forming a recorded image by supplying a developer by a developer supplying unit and applying a signal voltage to a recording electrode according to image information at this time to adhere the conductive developer to the recording medium to form a recorded image. There is a cleaning means for removing the conductive developer adhering to the recording medium, and a bias voltage having a reverse polarity is applied to the cleaning means only when the recording medium is conveyed, and the recording medium is stopped. Alternatively, the non-image area is provided with a bias means that does not apply the reverse bias voltage.

<Operation> According to the above means, the cleaning member for contacting the recording medium to remove the developer adhering thereto, and the bias for applying the bias voltage of the opposite polarity to the cleaning member only when the recording medium is conveyed. Since I have set up means
The reverse bias is not applied from the cleaning member when the recording medium is stopped.

Therefore, when the recording medium is in a stopped state, charges of opposite polarities are not injected more than necessary, so that the voltage is not applied from the recording control unit to the position where the recording medium and the cleaning member are in contact with each other. Also, the toner does not adhere and become dirty.

Further, the pinhole portion of the recording medium and the cleaning member do not come into direct contact with each other, so that toner does not adhere to the entire surface of the recording medium and become dirty.

Hereinafter, an embodiment of an image forming apparatus to which the present invention is applied will be described with reference to the drawings.

FIG. 1 is an explanatory sectional view showing a schematic configuration of an image forming apparatus;
FIG. 2 is an enlarged cross-sectional view of the recording medium used in the above device.

In FIG. 1, reference numeral 1 is a recording electrode for charging a developer according to image information, and the recording electrode 1 is for supplying a conductive magnetic developer (hereinafter referred to as “toner”) 2. It is densely attached along the axial direction to the outer peripheral surface of the non-magnetic cylinder 3 which is the developer supplying means.

A rotating magnet 4 is coaxially attached to the non-magnetic cylinder 3, and the magnetic field of the rotating magnet 4 conveys the toner 2 along the outer peripheral surface of the non-magnetic cylinder 3.

A part of an endless belt-shaped recording sheet 5 which is a recording medium for adhering the toner 2 to form an image is arranged close to the recording electrode 1. The recording sheet 5 is stretched between a driving roller 6 and a tension roller 7, which are a conveying means of the recording sheet 5 and are vertically separated from each other. The drive roller 6 is driven and rotated by a drive motor (not shown) to convey the recording sheet 5.

A recording controller 8 for applying a voltage according to image information is connected to the recording electrode 1. The recording control unit 8 applies a voltage according to image information to a conductive layer of the recording sheet 5 described later to adhere the toner 2 on the insulating layer to form an image.

As described above, the image formed on the recording sheet 5 is displayed outside when the recording sheet 5 is conveyed in the direction of arrow A by the rotation of the driving roller 6 and passes through the image display unit 9. Then, the recording sheet 5 that has passed through the image display unit 9 is stripped of the toner 2 adhering thereto by the cleaning member 12 fixedly mounted via the mounting member 11 mounted on the back plate 10 of the apparatus main body, and the toner 2 is removed. It drops onto the non-magnetic cylinder 3 and is conveyed again to prepare for the next recording.

The cleaning member 12 is a cleaning member main body 12a.
And a soft and conductive brush 2b, the brush 12
When b is at an appropriate angle and distance, the recording sheet 5 is rubbed to remove the attached toner 2.

Further, the cleaning member body 12a is the recording sheet 5
It is connected to a static elimination power supply 13 for applying a reverse bias to. The static elimination power source 13 has its bias controlled by a bias control switch 14. When the recording sheet 5 is in a stopped state, it is in an OFF state as shown by a solid line, and when the recording sheet 5 is in a conveyed state, as shown by a broken line. The operation is controlled so that it will be in the ON state. The charge history of the recording sheet 5 is erased by applying a voltage having a polarity opposite to that of the charge on the recording sheet 5 by the charge eliminating power source 13.

As the cleaning member 12, a material such as carbon fiber, soft plastic (polyethylene, polypropylene) which has conductivity by compounding, urethane rubber, silicon or the like is used.

Further, a non-magnetic member 15 and a magnet 16 for supporting the recording sheet 5 are provided at a position facing the cleaning member 12 which faces the recording sheet 5.

Next, the structure of the recording sheet 5 applied to the image forming apparatus configured as described above will be described with reference to FIG.

The recording sheet 5 is made of butyral resin, phenol resin,
Alternatively, a surface layer 5a made of a transparent material whose main component is urethane resin, a colored layer 5b made of a colored inorganic substance and an adhesive (acrylic resin, plastic resin), aluminum for imparting conductivity, or A conductive layer 5C having ITO (oxide of indium and tin) vapor-deposited thereon and a substrate 5b made of a plastic resin such as polyethylene terephthalate, polyethylene or polypropylene are polymerized.

The surface layer 5a and the colored layer 5b are electrically insulated. As the colored layer 5b, titanium oxide (TiO ₂ ), aluminum oxide (Al
An inorganic substance such as ₂ O ₃ ) was used.

According to the above configuration, the static elimination power supply 13 is suitable for the bias control switch 1 and when the recording sheet 5 is in the stopped state, the operation is controlled to the OFF state as indicated by the solid line, thereby making it unnecessary for the recording sheet 5. Charge is not injected, and therefore, the excess toner 2 does not adhere to the recording sheet 5,
Clear images can be formed.

<Other Embodiment> Next, another embodiment of the bias means for applying a reverse bias to the cleaning member applied to the above embodiment will be described with reference to FIG.

In FIG. 3, the overall structure of the apparatus is the same as that of the image forming apparatus shown in FIG.

In this embodiment, the reverse bias is not applied by the bias control switch 14 while the portion of the recording sheet 5 excluding the image display portion 9 slides on the cleaning member 12.

That is, when the recording sheet 5 is conveyed, the reverse bias from the cleaning member 12 is not applied to the area B in the drawing and the area C in the drawing when the recording sheet 5 is stopped.

According to the above configuration, since the reverse bias is applied from the cleaning member 12 only to the image display area of the recording sheet 5 and the reverse bias is not applied to the non-image area, the toner 2 adheres to the non-image area of the recording sheet 5. Can be prevented.

In each of the above-described embodiments, the cleaning member 12 was in the float state when the bias control switch 14 was in the OFF state, but the bias control switch 14 was set to 0V.
Alternatively, it is possible to more reliably prevent the toner 2 from adhering to the recording sheet 5 by switching to the apparatus main body grounding.

<Advantages of the Invention> As described above, the present invention applies a cleaning member for removing the developer adhering to the recording medium and a bias voltage of reverse polarity to the cleaning member only when the recording medium is conveyed. Since the bias means that does not apply the reverse bias voltage while the recording medium is stopped is provided,
The reverse bias is not applied from the cleaning member when the recording medium is stopped.

Therefore, when the recording medium is in a stopped state, electric charges having opposite polarities are not injected more than necessary, so that the voltage is not applied from the recording control unit to the position where the recording medium and the cleaning member are in contact with each other. Also, the toner does not adhere and become dirty.

Further, the pinhole portion of the recording medium and the cleaning member do not come into direct contact with each other, so that toner does not adhere to the entire surface of the recording medium and become dirty.

[Brief description of the drawings]

FIG. 1 is a cross-sectional explanatory view showing a schematic configuration of an image forming apparatus, FIG. 2 is an enlarged cross-sectional view of a recording medium applied to the above-mentioned apparatus, FIG. 3 is an explanatory view of another example, FIG. 4 and FIG. FIG. 6 is an explanatory diagram of a conventional example. 1 is a recording electrode, 2 is a toner, 3 is a non-magnetic cylinder, 4 is a rotating magnet, 5 is a recording sheet, 5a is a surface layer, 5b is a colored layer, 5c is a conductive layer, 5d is a base material, 6 is a drive roller, 7 is a tension roller, 8 is a recording control unit, 9 is an image display unit, 10 is a back plate, 11
Is a mounting member, 12 is a cleaning member, 12a is a cleaning member main body, 12b is a brush, 13 is a static elimination power source, 14 is a bias control switch, 15 is a non-magnetic member, and 16 magnets.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-59-181377 (JP, A) JP-A-58-76875 (JP, A) JP-A-50-81338 (JP, A)

Claims (1)

(57) [Claims] 1. A recording electrode is provided so as to face a recording medium conveyed by a conveying means, and a conductive developer is supplied between the recording electrode and the recording medium by a developer supplying means. An image forming apparatus for forming a recorded image by applying a conductive developer to the recording medium by applying a signal voltage according to image information, the conductive developer being attached in contact with the recording medium. And a biasing means for applying a reverse bias voltage to the cleaning means only when the recording medium is being conveyed, and not applying the reverse bias voltage to the recording medium while the recording medium is stopped or in a non-image area. An image forming apparatus comprising: