JPH04319978A - Transfer type recording device - Google Patents

Abstract

PURPOSE:To eliminate the necessity of using a highly rigid member and enable compact and lightweight design to be applied to a transfer type recording device where the reverse side of a recording sheet in contact with a toner image carrier is pressed by a pressing device, and a toner image formed on the toner image carrier is transferred to the sheet via pressure transfer, by applying the constitution wherein no external force is applied. CONSTITUTION:One of a pressure roller 6 and a toner image carrier has a builtin magnet 42, and the other has a builtin magnetic body. A recording sheet is pressed to the toner image carrier with a magnetic force generated between the magnet 42 and magnetic body.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure transfer device used in a recording apparatus that transfers a toner image on a toner image carrier onto a recording paper by pressure transfer to obtain a toner image on the recording paper.

0002

2. Description of the Related Art Electrostatic and electrophotographic recording devices are known as devices that transfer a toner image on a toner image carrier to a recording paper by pressure transfer to obtain a toner image on the recording paper. . In these devices, by using pressure transfer, good transfer characteristics can be achieved even on recording paper with poor smoothness, and a clear toner image can be obtained on the recording paper.

0003

However, pressure transfer requires a large pressing force. Therefore, in order to obtain the necessary pressing force uniformly on the recording paper, the pressing device of the pressure transfer device must be constructed of a member having high rigidity and must be pressed with a strong spring. For this reason, the pressure transfer device has the problem of becoming larger and heavier.

This will be explained using FIG. 8. The toner image carrier 401 is made of a photoreceptor, and the recording paper 402 comes into contact with the toner image carrier 401 and is pressed from behind by a pressure roller 403 . The toner image previously formed on the toner image carrier 401 is pressure-transferred onto the recording paper 402 by contact pressure generated between the recording paper 402 and the toner image carrier 401 . At this time, the pressure roller 403 needs to press the recording paper with uniform pressure. Therefore, it is composed of a cylindrical member with a uniform diameter of 2R. When loads C and D are applied to the shaft end, a bending moment is applied to the shaft to cause it to curve. As a result, if the bending rigidity of the pressure roller 403 is not sufficiently high, the pressure will be small at the center, and furthermore, a gap will occur. prevent this,
In order to obtain good transfer characteristics over the entire length of the pressure roller 403, it is necessary to configure the pressure roller 403 with a large diameter roller. The magnitude of the contact pressure generated between two members that are in contact with each other under pressure depends on the contact area.If the load is the same, the contact pressure when a roller with a large radius of curvature is brought into contact with a roller with a small radius of curvature is It will be smaller than when they are in contact with each other.

Therefore, if the diameter of the pressure roller is made small in order to obtain the necessary contact pressure, the bending rigidity of the pressure roller becomes insufficient, and if the diameter of the pressure roller is made large, it is necessary to increase the applied load. For this reason, the pressure transfer device has become larger and heavier.

An object of the present invention is to solve this problem and realize a transfer type recording apparatus that is small, lightweight, and can provide sufficient transfer pressure.

[0007]

[Means for Solving the Problems] The transfer type recording device of the present invention transfers a toner image formed on a cylindrical toner image carrier.
In a transfer type recording apparatus, a recording paper is brought into contact with the toner image carrier, and a pressure roller presses the recording paper from behind to transfer the toner image onto the recording paper by pressure transfer. At least one of the image carriers contains a magnet, and the other contains a magnetic material, and the recording paper is pressed against the toner image carrier by the magnetic force between the two.

[0008]

[Example] An example of the present invention will be explained.

FIG. 1 is a perspective view of a wet type recording apparatus according to an embodiment of the present invention.

A charging device 2, an exposure device 3 consisting of a laser scanner, a developer supply device 4, an elastic drum 5 serving as a toner image carrier are arranged around a photoconductor drum 1 made of a photoconductor.
A photosensitive drum cleaning device 7, a pressure roller 6, and an elastic drum cleaning device 9 are arranged in this order.

As shown in FIG. 3, the photosensitive drum 1 includes an amorphous selenium photosensitive layer 10 around an aluminum tube 100.
1 was deposited. It is configured to rotate in the direction of arrow A.

The developer supply device 4 guides a wet developer (hereinafter also referred to as developer) stored in a developer container 8 having a built-in supply pump to a coating head 202 serving as a developer supply means, and supplies the wet developer to a coating head 202 serving as a developer supply means. 1. Discharge onto the outer peripheral surface.

The configuration of the coating head 202 is shown in FIG. The coating head 202 is provided with the opening of the slit 72 facing the photosensitive drum 1 . The piezoelectric ceramic plate 121 and the metal plate 122 face each other across the microgap of the slit 72. The piezoelectric ceramic plate 121 has electrodes 123, 1 on both sides.
24, and when a high frequency voltage is applied between them, the arrow F
It expands and contracts in the direction of . In this embodiment, the piezoelectric ceramic plate 1
As 21, a PZT plate having a thickness of 1 mm is used, a wet type developer 56 is supplied to a gap of 20 μm, and the wet type developer 56 is driven at 1.8 MHz and vibrated in the direction of arrow F to fly as droplets.

The wet developer 56 consists of Label 1255 of Columbia Carbon Co., Ltd. and ethyl cellulose as pigments in a high resistance, low dielectric constant aliphatic hydrocarbon solvent (for example, Exxon Chemical Co.'s Isopar G) as a dispersion medium. It is composed of toner particles dispersed together with an organic amine charge control agent. The apparatus of this embodiment uses positively charged toner particles.

As shown in FIG. 3, the elastic drum 5 has an elastic layer 116 on a metal tube 112 having magnetism. This is composed of a conductive layer 113 made of conductive urethane rubber in which a conductive compound is dispersed, and an insulating layer 114 made of a fluororesin coating layer as the outermost layer.
The photoreceptor drum 1 is rotated in the direction of arrow B at the same speed as the photoreceptor drum 1 .

The charging device 2 is composed of an elastic conductive roller to which a predetermined voltage is applied by a high voltage power source, and charges the surface of the photosensitive drum 1.

The exposure device 3 is composed of a laser beam scanner, and forms an electrostatic latent image on the photosensitive drum 1 by controlling a laser beam according to image data from a computer and performing selective exposure. The configuration of the pressure roller 6 is shown in Figure 4.
Shown below. A cylindrical magnet 42 is placed around a shaft 41 made of a magnetic material.
, and is rotatably supported with a structure in which the periphery is further covered with a rubber layer 43. It rotates at the same speed as the elastic drum 5. The magnet 42 is magnetized so that magnetic poles are arranged at equal intervals in the circumferential direction. Since the elastic roller 5 has magnetism, magnetic flux leaking from the magnetic poles of the magnet 42 constituting the pressure roller 6 generates an attractive force, and the recording paper 2 is drawn toward the elastic roller 5.
Press 1.

Next, the operation will be explained.

The charging device 2 charges the photosensitive drum 1 to a positive potential. In the exposure step, an electrostatic latent image corresponding to the image is formed on the photoreceptor drum 1. As a result of neutralizing the surface charge in the exposed portion, an electrostatic latent image is formed on the photoreceptor drum 1.

The toner image forming operation will be explained with reference to FIG. The surface of the photoreceptor drum 1 is uniformly charged with a positive charge and has a positive surface potential (+500 V in this embodiment), and after the exposure process, the exposure section 105 has a substantially ground potential (for example, +4
0V), and the non-exposed portion 104 is at a positive potential (+50V in this embodiment).
0V) and enters the contact portion 117 with the elastic drum 5. The contact portion 117 holds the wet developer 56 supplied from the coating head 202 . The elastic drum 5 is powered by a power source 102
Therefore, the positive potential is maintained at a value lower than the positive potential of the non-exposed area (+50 V in this embodiment). The wet developer layer 56 is
Since it has a positive charge, when it passes through the contact part 117 between the photoreceptor drum 1 and the elastic drum 5, it is directed toward the photoreceptor drum 1 in the exposed area and towards the elastic drum in the non-exposed area, depending on the electrostatic force. 5 receives an electrostatic force. As a result,
A developer layer 1 is applied to the elastic drum 5 in the area corresponding to the non-exposed area.
09 is attached. On the other hand, an electrostatic force acts on the exposed area so that the developer adheres to the photoreceptor drum 1, but due to the above potential relationship, the attraction force between the photoreceptor drum 1 and the developer is not large, so the contact area It is subjected to a squeezing action by the pressing force of 117 and is peeled off and removed. On the other hand, the carrier liquid is also subjected to a throttling action, and movement of the contact portion 117 downstream is prevented. These stay in the retention part 115 on the upstream side of the contact part 117.

The recording paper 21 is conveyed to the transfer area as the toner image is formed, and the toner image is transferred from the elastic drum 5 to the recording paper 21 under pressure from the pressure roller 6. That is, the toner image is pressurized by the pressure roller 6 and generates adhesion force with the recording paper 21 due to the pressure, and the toner image is pressed by the elastic drum 5.
The image is transferred from the recording paper 21 to the recording paper 21.

Residual toner on the photosensitive drum 10 and elastic drum 5 is removed by a photosensitive drum cleaning device 7 and an elastic drum cleaning device 9.

The pressure roller 6 of this embodiment includes an elastic roller 5.
An attractive force acts magnetically between the two. Therefore, there is no need to apply external force such as a spring. When applying an external force to a specific point using a spring or the like, a member with high bending rigidity is required, as described in the related art. Furthermore, since the spring support part is also subjected to a reaction load, it needs to be made of a member with high rigidity. However, in the configuration of this embodiment, pressure is generated evenly in the contact portion, and no force is applied to the outside. Therefore, the strength of the portions supporting the elastic roller 5 and the pressure roller 6 is not required, and the device can be simplified and miniaturized.

A second embodiment is shown in FIG. In this figure, only the configuration of the pressure roller 6 is shown. It has a structure in which disk-shaped magnets 42 are stacked and arranged around a shaft 41. The magnet 42 is magnetized so that the direction of magnetization coincides with the direction of the axis 41. By making the magnet 42 thinner, a magnet shape with a small permeance coefficient is possible, a magnet material with a large energy product can be used efficiently and economically, and a strong transfer pressure can be obtained. The operation and other operations are the same as those in the previous embodiment, and the explanation will be omitted.

A third embodiment is shown in FIG. Pressure roller 6
Only the configuration is shown. A disc-shaped magnet 42 is placed around the shaft 41.
It has a structure in which it is stacked and arranged together with a disc-shaped yoke 44 made of a magnetic material. The direction of magnetization of the magnet 42 is in the direction of the axis 41. Since the magnetic flux generated by the magnet 44 is efficiently drawn out by the yoke 42, a large attractive force can be obtained.

A fourth embodiment is shown in FIG. Supported by a shaft 71, a plate magnet 42 and a low-friction plastic bush 72 are integrated. The magnet's magnetization direction coincides with the plate thickness direction indicated by E. These components are built into a pipe 73 made of a non-magnetic material and having an inner diameter larger than that of the plastic bush 72. The magnetic field from the magnetic poles of the magnet 42 generates an attractive force between the magnet 42 and the elastic roller 5, which presses the pipe 73 through the plastic bush 72. pipe 7
3 rotates at the same speed as the elastic drum 5, and the magnet 42 and plastic bush 72 do not rotate. The outer peripheral surface of the plastic bush 72 slides on the pipe 73. The magnet 42 is always stationary with its magnetic pole face facing the elastic drum 5. The pressing force on the pipe 73 acts on a specific part of the pipe 73, but by appropriately setting the pitch at which the plastic bushings 72 are provided, taking into account the rigidity of the pipe 73, the axis of the pressure acting on the recording paper 21 can be adjusted. Uniform pressurization with small directional distribution is possible. When a load that generates a bending force acts on a shaft-like member, the bending rigidity of the shaft-like member and the amount of bending deformation determined by the load are used as an index of the non-uniformity of the transfer pressure,
Using the bending displacement analysis formula for a beam supported at both ends, this can be approximately evaluated using the following formula.

(Transfer pressure non-uniformity) = (load) / ((distance between load application points) cubed) The case of applying a load to both ends of the pressure roller shown in the conventional example and the case of this example Comparing the cases, since the distance between the load application points can be made sufficiently small, the required rigidity of the pipe 73 is much smaller than that of the pressure roller shaft in the conventional configuration. The same applies to the first to third embodiments.

Although the embodiments have been described with reference to a transfer type recording apparatus using a wet type developer, the present invention is not limited thereto, and the present invention is applicable to an apparatus using a dry type developer, an apparatus using an ion flow without using a photoconductor, etc. The present invention is also effective for devices that perform recording by controlling magnetic latent images or controlling magnetic latent images.

[0029]

Effects of the Invention In the transfer type recording device of the present invention, one of the pressure roller and the toner image carrier has a built-in magnet, and the other has a built-in magnetic body, and the magnetic force between the rollers and the toner image carrier moves the recording paper into a toner image. It is configured to be pressed against the carrier.

[0030] Therefore, since a direct suction and attraction force is generated between both rollers, there is no need to apply any force from the outside. Therefore, the members constituting the device do not require high strength, and a small and lightweight device can be realized with a simple configuration.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the configuration of a transfer type recording apparatus according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing the operation of the coating head used in the transfer type recording apparatus according to the first embodiment of the present invention.

FIG. 3 is a diagram showing the operation of forming a toner image in the transfer type recording apparatus according to the first embodiment of the present invention.

FIG. 4 is a perspective view showing the configuration of a pressure roller used in the transfer type recording apparatus according to the first embodiment of the present invention.

FIG. 5 is a perspective view showing the configuration of a pressure roller used in a transfer type recording apparatus according to a second embodiment of the present invention.

FIG. 6 is a perspective view showing the configuration of a pressure roller used in a transfer type recording apparatus according to a third embodiment of the present invention.

FIG. 7 is a perspective view showing the configuration of a pressure roller used in a transfer type recording apparatus according to a fourth embodiment of the present invention.

FIG. 8 is a diagram illustrating the operation of a transfer type recording device equipped with a conventional pressure transfer device.

[Explanation of symbols]

1: Photosensitive drum 4: Developer supply device 5: Elastic drum (toner image carrier) 6
: Pressure roller 41 : Shaft 42 : Magnet 43 : Rubber layer 44 : Yoke 71 : Shaft 72 : Plastic bush 73
:pipe

Claims (1)

[Claims] 1. A toner image formed on a cylindrical toner image carrier is transferred by pressure transfer by bringing a recording paper into contact with the toner image carrier and pressing the recording paper from behind with a pressure roller. In a transfer type recording device that obtains a toner image on recording paper, at least one of the pressure roller or the toner image carrier has a built-in magnet, and the other has a built-in magnetic material, and the magnetic force between them is used to move the recording paper. A transfer type recording device characterized in that it is configured to press against a toner image carrier.