JPH07111594B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention forms a multicolor toner image on the surface of a photoconductor by repeating a series of steps of uniform charging, image exposure and development on the photoconductor. The present invention relates to improvement of means for preventing toner scattering due to image exposure of second and subsequent colors of an image forming apparatus to be formed.

(Prior Art) In an image forming apparatus that repeats the steps of uniform charging, image exposure, and development a plurality of times on a photoconductor to form a plurality of color toner images, and transfers the toner images to a transfer material, The surface of the photoreceptor on which the color has been developed is uniformly charged again by the charger, and then image exposure is performed using the image signal corresponding to the second color, and the latent image formed by this is stored in the second color toner. The developing device thus formed forms a second-color toner image on the surface of the photoconductor on which the first-color toner image has already been formed so as to be superposed.

Hereinafter, when the third and fourth colors are present, the same process is repeated to form the toner images of the respective colors so as to be superimposed.

In this way, after a superposed toner image for a preset color is formed, this is transferred to a transfer material to form a color image.

(Problems of the Prior Art) As described above, in the multiple toner image forming process in which charging, exposure, and development are repeated many times, after the toner image formed in the first process is charged, the vicinity of the image is exposed. If so, the electric field distribution in the vicinity of the image changes abruptly, so that the toner scatters due to the repulsive force between the toner particles and adheres to the portion where the Coulomb force acts. This tendency is particularly remarkable in the case of reversal development.

FIG. 5 is an explanatory diagram of causes of toner scattering.

The vertical axis in FIGS. 5A to 5E indicates the negative potential of the surface of the photoconductor (hereinafter, the uniform charging is described as negative charging), and the horizontal axis indicates the position of the surface of the photoconductor. . FIG. 3A shows a state where the surface of the photoconductor is uniformly charged to a potential of −E volt by the charger.

FIG. 6B shows that the range indicated by L of the photoconductor is exposed, and the potential of that part becomes close to 0 volt. FIG. 6C shows that when the exposed portion L of the photoconductor passes through the developing device, the toner negatively charged from the developing sleeve having the same potential as the uniform charging potential of the photoconductor is exposed to the photoconductor. It shows a state in which the toner flies toward the portion L, adheres to the exposed portion and is developed. In this way, the surface of the photoconductor on which the toner image of the first color is formed is subjected to the second uniform charging by the charger while the toner image is still formed.

Part (d) of FIG. 7 shows the potential during the second uniform charging.

Next, image exposure is performed with an image signal corresponding to the second color. In the figure (e), image exposure is performed in the vicinity L ′ of the toner image of the first color and the potential of that portion is close to 0 volt (that is, the potential of the portion L ′ is higher than the portion L).
Indicates that.

By the way, each toner particle of the toner image of the first color adheres to the surface of the photoconductor due to Coulomb force or the like between the toner particles and the photoconductor, but the toner particles are electrically charged because they have the same polarity. Has a repulsive force. On the other hand, since the toner particles are negatively charged, if there is a portion having a higher electric potential than the current position, a force to move the toner particles to the higher electric potential acts along the direction of the electric field formed there. If the force to move the toner is larger, the toner jumps out to the higher potential.

Part (f) of FIG. 6 is a situation diagram in which a part of the toner attached to the L portion where the potential is −E volt scatters while trying to move to the L ′ portion where the potential is close to 0 volt.

In this way, if toner scattering occurs when image exposure corresponding to the next color is performed on the photoconductor on which the toner image is previously formed, a part of the scattered toner adheres to the dust-proof glass in the image exposure device. Then, there is a problem that the transmittance of the image exposure light is lowered or unevenness is caused.

FIG. 6 is a diagram showing a situation in which the scattered toner adheres to the dustproof glass. That is, when the toner 7 of the toner image formed on the surface of the photoconductor 5 is image-exposed by the laser light 3, a part of the toner scattered as shown in the figure is a frame 8.
To the dust-proof glass 4 and reach the dust-proof glass 4 and attach to it.

Thus, there is a problem that the inside of the machine is contaminated and the toner attached to the dustproof glass hinders the transmission of the laser light 3.

In order to solve this problem, the inventors of the present invention provided an electric field forming means for preventing toner scattering, such as the slit electrode 9 shown in FIG. 3 and the conductive electrode member 11 shown in FIG. The present invention has been applied for by the applicant of the present application, in which the above structure is suppressed, and even if there is scattered toner, the toner does not easily reach the dustproof glass.

In FIG. 3, a slit electrode 9 having a slit 14 is provided, and a voltage having the same polarity as the charging polarity of the photoconductor and an absolute value equal to or larger than the absolute value of the charging potential of the photoconductor 5 is applied to the slit electrode 9. As a result, an electric field that suppresses toner scattering is formed between the surface of the photoconductor 5 and the surface of the photoconductor 5. This electric field suppresses the toner scattering, and the absolute value of the photoconductor 5
When a voltage larger than the absolute value of the charging potential is applied, a force that pulls back the scattered toner toward the photoconductor 5 acts.

Further, since the slit 14 is a narrow passage, there is an effect that scattered toner does not easily reach the dustproof glass 4.

The electric field forming means of FIG. 4 has a cross-sectional shape that is thicker in the vicinity of the slit 14 and becomes thinner as the distance from the slit 14 increases, and the slit electrode 9 is provided with a conductive electrode member 11 below a resin slit member 10. It has a different structure.

The slit electrode 9 is mounted so that it can be slidably fixed by fitting a rail 12 provided on the frame body 8 of the image exposure device 6 and a groove 13 provided on the slit electrode 9 from the front of the image forming apparatus main body. It has a detachable structure.

With the above-described configuration, the electric field strength near the slit 14 is increased, and the toner is prevented from entering the slit 14. Further, as the thickness of the slit 14 increases, the ratio of the toner that has entered the slit 14 to the inner wall of the slit 14 increases, and as a result, the toner that adheres to the dustproof glass 4 decreases. In addition, in the space between the slit electrode 9 and the photoconductor 5, an air flow often exists due to the rotation of the photoconductor 5 or an exhaust fan attached to the apparatus, but the slit electrode 9 has a smooth shape. As a result, the turbulent flow around the slit electrode is reduced, and the adhesion of floating toner is prevented.

However, in these examples, since the slit electrode 9 and the conductive electrode member 11 are exposed on the surface on the photoconductor side,
An image force acts between the conductive electrode member 11 and the charged toner floating in the vicinity thereof, and a part of the toner scattered from the photoconductor 5 adheres, or a small amount of reverse polarity charged toner adheres. However, if these are deposited to a certain extent, the deposited toner will drop onto the photoconductor when the power of the device is turned off or when mechanical vibration or shock is applied to the device, destroying the toner image being formed. There is also a problem that the inside of the device is contaminated.

Further, when performing maintenance work with the photoconductor removed, there is a problem that a dangerous state may occur because the electrodes are exposed.

In order to solve the above-mentioned problems, an object of the present invention is to prevent toner from adhering to the electrode member and the dielectric member by providing a dielectric member on the photosensitive member side of the electrode member and to provide a highly safe image in maintenance work. To provide a forming apparatus.

(Means for Solving Problems) The present invention has the following means configuration in order to achieve the above object. That is, the image forming apparatus of the present invention is
An image forming apparatus for forming a multicolor toner image on the surface of a photoreceptor by repeating a series of steps of uniform charging, image exposure and development a plurality of times, wherein dust-proof glass of the image exposure apparatus and the photoreceptor are: An image characterized by having a dielectric having a slit as an optical path for image exposure, and an electrode member for forming an electric field for pushing toner toward the photoconductor between the photoconductor and the dustproof glass side of the dielectric. It is a forming device.

(Operation) In the image forming apparatus of the present invention, a dielectric having a slit as an optical path for image exposure is provided on the photoconductor side of the electrode member. Therefore, the toner scattered from the surface of the photoconductor is blocked by the dielectric and does not adhere to the electrode member. Further, the position of the surface of the dielectric on the photoconductor side is separated from the electrode member by the thickness of the dielectric, and the force at this position to attract and attach the toner to the dielectric is directly applied to the electrode member. The toner is less likely to adhere because it is smaller than in the above case.

Regarding safety, when viewed from the photoconductor side, the electrode member is not directly exposed because it is blocked by the dielectric, so the human body or something else touches the electrode member even when working with the photoconductor removed. There is no increase in safety.

(Example) Hereinafter, the Example of this invention is described based on drawing. First
FIG. 6 is a diagram showing an example of the positional relationship between the image exposure means and the photoconductor of the image forming apparatus of the present invention.

11 'is a conductive electrode member as a toner scattering prevention electrode, 1
Reference numeral 0'denotes a resin slit member as a dielectric, which has slits 14.

In this embodiment, the conductive electrode member 11 'is realized by a conductive sheet. The resin slit member 10 'and the conductive electrode member 11' are placed between the dustproof glass 4 and the photoconductor 5 of the image exposure device 6, and the conductive electrode member 11 'is placed on the photoconductor 5 side. It is arranged.

The conductive electrode member 11 'has the same polarity as the charging polarity of the photoconductor,
A voltage whose absolute value is equal to or larger than the absolute value of the charging potential of the photoconductor is applied to form an electric field between the photoconductor 5 and the photoconductor 5, thereby suppressing scattering of the toner of the toner image on the photoconductor 5. The resin slit member 10 'is attached to the frame body 8 with a rail structure so as to keep a space of about 5 mm from the surface of the photoconductor 5 and is slidable in a direction perpendicular to the plane of the drawing. There is. For this reason, it is easy to attach and detach from the front surface of the device, and the maintainability is improved.

FIG. 2 shows another structural example of the resin slit member 10 and the electrode member. FIG. 2A shows a structure in which the slit portion is also blocked by the electrode member with a transparent conductive film. This can completely prevent the scattered toner from reaching the dust-proof glass. FIG. 2B shows a structure in which the conductive electrode member 11 'is folded into the slit portion to prevent scattered toner from passing through the slit.

(Effects of the Invention) As described above, in the image forming apparatus of the present invention, since the dielectric member is provided between the dustproof glass and the photoconductor of the image exposure device and the electrode member is provided on the dustproof glass side, the scattered toner is scattered. Does not adhere to the electrode member, and is also unlikely to adhere to the surface of the dielectric on the photoconductor side. Therefore, the adhered and deposited toner falls on the photoconductor and destroys the toner image being formed,
There is an advantage that the inside of the device is not polluted.

Further, there is an advantage that it is safe because the electrode member is not exposed even when the photoconductor is removed.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a main part of an apparatus according to an embodiment of the present invention, FIG. 2 is a diagram showing a configuration example of a resin slit member and an electrode member, and FIGS. 3 and 4 are the present inventors. FIG. 2 is a diagram showing a configuration example of an electric field forming means for preventing toner scattering, which is invented by
FIG. 5 is an explanatory diagram of causes of toner scattering, and FIG. 6 is a status diagram of toner scattering. 1 ... Charger, 2 ... Mirror, 3 ... Laser light, 4 ...
Dust-proof glass, 5 ... Photoconductor, 6 ... Image exposure device, 7 ...
Toner, 8 ... Frame, 9 ... Slit electrode, 10, 10 '...
... Resin slit member, 11, 11 '... Conductive electrode member, 1
2 …… rail, 13 …… groove, 14 …… slit, 15 …… transparent conductive film.

Claims (1)

[Claims] 1. An image forming apparatus for forming a multicolor toner image on a surface of a photoconductor by repeating a series of steps of uniform charging, image exposure and development on the photoconductor, the image exposing device comprising: A dielectric having a slit as an optical path for image exposure between the dustproof glass and the photoconductor, and an electrode for forming an electric field between the photoconductor and the dustproof glass side of the dielectric to push the toner toward the photoconductor. An image forming apparatus comprising: a member.