JPS6083058A - Image forming device - Google Patents

Abstract

PURPOSE:To enable clear-cut image formation without lowering image contrast by irradiating light information on an image carrier at a position corresponding to a part of intrusion of developer between a sleeve and image carrier. CONSTITUTION:Developer 5 presents a chainlike form at a position where an image carrier stands closest to a sleeve 7. In a temporary puddle of developer in the upstream side of the position of chainlike form in the direction of rotation of the sleeve, circulating flow of developer is generated by a flow C of developer generated by movement of the sleeve 7, blocking of the flow C by the chain of developer at nearest part, and a flow D of developer generated by movement of the image carrier 1 in the direction of arrow mark (c). Particles of developer in the circulating flow moves in scattered state the influenced by strong magnetic force, and the flow is in the state of turbulence. When light information L is irradiated on the image carrier 1 corresponding to the position of developer in turbulent state, developer which is not in chainlike form adheres to the image carrier. Accordingly, unclearness of the picture and lowering of contrast due to destruction of the chainlike developer do not take place even when magnetic field becomes weak due to movement of the image carrier.

Description

[Detailed Description of the Invention] The present invention is applicable to a display device or a copying device that reproduces image information output from an image reading device or image information stored on a magnetic tape or the like as an image for viewing. It relates to an image forming apparatus that forms an image as a visible image on an image carrier using a developer.0 Such an image forming apparatus does not require a charging process and can form an image with a simple configuration. An image forming apparatus that can be used includes a developer carrier that supports a conductive magnetic developer on its surface by magnetic force, a conductive substrate whose photoconductive layer side faces the developer on the carrier, and a photoconductive layer. A method is known that uses a carrier, a means for irradiating optical information from the conductive substrate side of the photoreceptor, and a means for applying an insulating pressure between the developer and the conductive substrate. An example of this method is
Japanese Patent Publication No. 58-98748, 987 by the source of the present application
There is a disclosure in Publication No. 49. The image forming principle of the above method is explained as follows.
This will be explained with reference to the drawings and FIG.

In the figure, an image carrier 1 includes a transparent support 4 such as a polyethylene terephthalate film, and a transparent support 4 on which Snow, I
It has a conductive base made of a transparent conductive layer 3 formed by vapor deposition such as nzOs, and a photoconductive layer 2 which is an N-type photoreceptor such as CaS. Further, the developer 5 is a conductive magnetic toner, and this developer is held on a non-magnetic sleeve 7 made of aluminum, stainless steel, etc., which is a developer carrier, by the magnetic field of a magnet roller 6, which is a magnetic force generating means. . Then, as this developer drain sleeve 7 rotates in the direction of the arrow, it passes through the gap between it and the image carrier 1 . A bias voltage is applied by a power source 8 between this sleeve and the isoelectric layer 6 of the image carrier.

FIG. 1 shows the state of charge in the bright part of the original information. When the developer 5 to which a voltage is applied via the sleeve 7 comes into contact with the image carrier 1, an electric field is applied to the photoconductive layer 2. At this time, when optical information is irradiated, photocarriers e are generated in the photoconductive layer 2, and these photocarriers are guided near the surface of the photoconductive layer 2 by the action of an electric field. As a result, a strong electrostatic attraction acts between the developer 5 and the photoconductive layer 2,
The developer 5 is deposited on the photoconductive layer 2 , that is, on the surface of the image carrier 1 .

FIG. 6 shows the state of charge in the dark area. By applying an electric field between the developer 5 and the transparent conductive layer 6 of the substrate, electrostatic attraction acts between the two, but since there is a photoconductive layer 2 between them, they are separated by a distance. Because it is there, its power is small. Therefore, the developer 5 is pulled away from the photoconductive layer 2, that is, the surface of the image carrier 1, due to the magnetic force generated by the magnet roller 6 provided inside the fixed sleeve 7, the adhesive force between the developer 5 particles, etc. It is announced.

In image formation using the above method, since the developer made of magnetic toner moves on the sleeve under the action of the magnetic field,
The developer moves in a chain shape (FIG. 3) as shown in state A between the sleeve and the image carrier. For this reason, optical information is
It is thought that it is better to perform this at a position in a chain because it is not affected by other chains. However, in reality, the developer 5 remains chained at the position of the magnetic pole, but the image carrier 1 moves (arrow a) K
As a result, the magnetic field weakens, and the developer chain breaks down, causing it to scatter (Status B)
(Figure 6). As a result, the image formed by the developer on the image carrier may become unclear, or background stains may occur due to the developer, resulting in a reduction in image contrast.

An object of the present invention is to solve the above-mentioned problems and provide a sharp image forming apparatus (42) without deterioration of image contrast.

Misfire #'J, which achieves the above purpose, is caused by the turbulent flow of developer between the sleeve and the image carrier, which is caused by the relative movement between the sleeve carrying the developer and the developer in an apparatus having the above configuration. The image carrier K at a position corresponding to the area is irradiated with the above optical information, and an image formed by a developer corresponding to this optical information is formed on the image carrier.

Hereinafter, the present invention will be explained in more detail according to examples.

FIG. 4 is a sectional view of an image forming apparatus to which the present invention is applied;
↑l Leave of absence appears f! agent 5, and 'f3. The toner carrier 7 and the magnet roller 6, which is a magnetic force generating means inside the carrier 411, are the same as those described in FIGS. 1 and 2 above.

In the figure, a magnet roller 61. t: S pole and N pole on the circumferential surface
The poles are alternately magnetized and are fixed at the positions shown in the figure. Then, only the sleeve 7 rotates in the direction indicated by the arrow C, and at the same time, the image carrier 1 moves in the direction indicated by the arrow C. After the developer 5 supported on the sleeve 7 adheres to the sleeve in the container/vessel 9, its application is restricted by the regulating plate 1o and reaches the optical information irradiation position.

By the way, in the above device, as shown in FIG. 5, the developer is (11
However, on the upstream side of this narrow position in the direction of rotation of the sleeve, the transported developer temporarily accumulates to form a developer reservoir. In this developer reservoir, a developer flow C occurs due to the movement of the sleeve 7, a chain caused by the developer at the closest portion blocks this flow C, and the image carrier 1 moves in the direction of arrow C. A developer flow D is occurring.

Therefore, in this developer reservoir, a circulating flow of the developer occurs due to the flow in the directions of arrows C and D. The developer in this circulating flow is not affected by strong magnetic force, and the developer particles circulate and move in a turbulent state.

The image carrier 1 is irradiated with optical information corresponding to the position of the developer in this turbulent flow state. As a result, non-chain developer adheres to the image carrier, so even if the magnetic field weakens, image blurring and contrast may occur due to the collapse of the chain developer as described above. This eliminates the possibility of a decrease in

In the above embodiment, the turbulent flow portion of the developer is located at the upward rotational position of the sleeve, but it may be located at the downward rotational position. In each case, the relationship of gravity has a large influence, so the optimum conditions are set by adjusting the amount of developer conveyed.

In the embodiments shown in FIGS. 4 and 5, the sleeve 7 is rotated and the magnet roller 6 is fixed. However, it is also possible to rotate the magnet roller and fix the sleeve. Specifically, in the apparatus shown in FIG. 4, the sleeve 7 is fixed and the magnet roller 6 is rotated in the opposite direction to the direction indicated by the arrow.

As a result, the developer on the sleeve moves in the direction of the arrow in the same manner as above. However, the turbulent flow portion of the developer in this case is not formed by the chain of the developer due to the turbulence, and the movement of the image carrier and the obstruction of the developer by the gap formed between the image carrier and the sleeve are large. have a strong influence. In particular, when the 3A developer is conveyed by the rotation of the magnetic roller, a certain button is formed by the developer at the closest position between the image carrier and the sleeve, so it is necessary to reduce the gap between the image carrier and the sleeve. The distance of this gap greatly affects the formation of turbulent flow.

Incidentally, in any of the above embodiments, the turbulent flow portion of the developer corresponding to the position where optical information is irradiated is formed at a position where the image carrier moves away from the developer. However, for example, by moving the image carrier 1 in the direction opposite to the arrow C in FIG. and the closest position of the sleeve. However, in this case, since there is no developer blocking force caused by the moving direction of the image carrier 1, it is necessary to reduce the gap between the image carrier and the sleeve 7 to compensate for the developer blocking force.

In this case as well, the turbulent flow portion of the developer can be formed not only at the upward rotational position of the sleeve but also at the downward rotational position. Especially when moving to the downward rotation position (
In order to further reduce the effect of stopping the developer, it is necessary to increase the amount of developer conveyed or to reduce the gap between the two members to compensate for the effect of stopping the developer. Further, as described above, even if the sleeve 7 is fixed and the magnet row 26 is rotated, the above-mentioned turbulent flow portion can be formed by setting the conditions.

As in the latter embodiment, the developer image formed on the image carrier 1 by irradiating the turbulent flow part of the developer with original information is further passed through the gap between the image-LID carrier and the sleeve 7. In this case, a strong magnetic force acts on the image carrier 1 in this gap.

As a result, the developer that has inadvertently adhered to the image carrier can be effectively removed by the magnetic force, and it is possible to prevent the image from being blurred.

By the way, in the above embodiment, the image carrier was C.
Using dS as an example, we used 6 bodies with N-type sensing, but it is also possible to apply other photoconductors, and depending on the characteristics of the photoconductor, bias power supply 8
Setting the polarity of 0 Furthermore, there is a dielectric layer on the surface of the image carrier to strengthen the adhesion of the developer, and when used in a display device such as the one described in the above publication, a dielectric layer is provided on the surface of the image carrier to easily remove the stuck developer. A color layer for visual recognition may be provided. In addition, optical information includes a laser beam modulated to form an image, information from an LED element array, and reflected light from a slit-shaped original.
In addition to the web shape, the transparent support 4 may be in the form of a plate or a drum. In this case, the transparent support 4 is made of a rigid body such as glass or transparent resin. The developer carrier is not limited to a sleeve, but may have a structure such as an endless belt. If the developer image formed on the image carrier is used only for display, it returns to the development position after display and is incorporated into the developer on the sleeve. On the other hand, in recording devices and copying devices, the formed developer image is transferred to another image carrier and consumed.

As described above, in the present invention, the irradiation position of the optical information onto the image carrier is set in the turbulent flow portion of the developer on the opposite side of the image carrier from the side where the optical information is irradiated. In this way, since the light 1n signal is not irradiated at the magnetic pole part where the developer is chained,
It has become possible to effectively prevent blurring and image fog caused by blurring of developer images due to the collapse of developer chains after development.

[Brief explanation of the drawing]

1 and 2 are explanatory diagrams explaining the image forming principle of the present invention, and FIG. 6 is an enlarged schematic diagram of the developing section of the image forming method of FIG. 1.
FIG. 4 is a sectional view of an image forming apparatus to which the present invention is applied, and FIG. 5 is an enlarged schematic diagram of the developing section of the present invention. In the figure, 1 is an image carrier, 2 is a photoconductive layer, 3 is a transparent electrode, 4 is a transparent support, 5 is a developer, 6 is a magnet roller that generates magnetic force, 7 is a sleeve which is a developer carrier,
8 indicates a bias power supply, and L indicates optical information. Applicant Canon Co., Ltd.

Claims (1)

[Claims] (1) A developer carrier that magnetically supports a conductive magnetic developer on its surface, and an image carrier that has a conductive substrate and a photoconductive layer with the photoconductive layer side facing the developer on the carrier. ,
In an image forming apparatus having means for irradiating optical information from the conductive substrate side of the photoreceptor and means for applying a bias voltage between the developer and the conductive substrate, a combination of the developer carrier and the developer is provided. The above-mentioned optical information is irradiated onto the image carrier at a position corresponding to the developer turbulence between the developer carrier and the image carrier caused by the relative movement, and an image formed by the developer corresponding to this optical information is formed on the image carrier. An image forming device characterized in that it is formed on the body.