JP2565969Y2 - Electrophotographic recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Purpose of the Invention] (Industrial application field) The present invention relates to a structural improvement of a transfer device for stabilizing image quality in an electrophotographic recording device.

(Prior Art) FIG. 3 conceptually shows a general configuration of a conventional electrophotographic recording apparatus, wherein 1 is a photosensitive drum, 2 is a developing device,
3 is a recording paper, 4 is a transfer charger, 5 is an insulator, 6 is a small-diameter rubber roller for conveyance, 7 is a slip ring, 8a and 8b are registration rollers, and 9 is a registration guide.

To record an image with this apparatus, first, an electrostatic latent image corresponding to an image signal is formed on the peripheral surface of the photosensitive drum 1 in an exposure process.

Next, in the developing process, the developing device 2 is rotated in synchronization with the photosensitive drum 1, and a developer is attached to the electrostatic latent image to form a so-called toner image.

The conveyance of the recording paper 3 from the registration rollers 8 (8a, 8b) is started at a predetermined timing according to the exposure and development processes.

Thereafter, the recording paper 3 passes through the registration guide 9 and reaches the photosensitive drum 1, and is further conveyed with its rotation while being wound around the peripheral surface of the photosensitive drum 1 while being assisted by the conveying small-diameter rubber roller 6. .

In the transfer process performed in accordance with the conveyance, a corona discharge is applied from the back surface of the recording paper 3 wound around the photosensitive drum 1 by the transfer charger 4 to transfer the toner image on the photosensitive drum 1 to the front surface.

The recording paper 3 onto which the toner image has been transferred in this manner is separated from the photosensitive drum 1 at a required position, and is turned to a fixing process.

In the fixing process, the toner image is firmly fixed on the recording paper 3 by a heating or pressing action from a fixing device (not shown), and is discharged as a stable recorded image.

In the electrophotographic recording mechanism having such a configuration, if the transfer current from the transfer charger 4 is concentrated on the protruding portion on the recording paper 3 entry side in the case, the transfer efficiency is reduced and the image quality is likely to be disturbed.

In order to prevent this, an insulator 5 is provided so as to partially cover the protruding portion.

A slip ring 7 is also provided as a configuration for improving the image quality.

On the other hand, during the execution of the electrophotographic recording process as described above, the conveyance small-diameter rubber roller 6 is charged to the same polarity as that of the electrode of the transfer charger 4, and the recording paper 3 is placed on the peripheral surface before the recording paper 3 is wound around the photosensitive drum 1. In order to attract the attached toner image, the image may be scattered or, in an extreme case, the machine may stop due to the leak current.

To prevent this, a slip ring 7 is attached, and the small-diameter rubber roller 6 is grounded to ground to suppress the charging of the electric charge accompanying the transfer process.

However, in the configuration of such a conventional electrophotographic recording apparatus, the slip ring 7 provided to suppress charging of the small-diameter rubber roller 6 also promotes the function of directing the transfer current from the transfer charger 4 toward the small-diameter rubber roller 6. As a result, the transfer current interrupting function inherent to the insulator 5 is attenuated.

As a result, the current flowing from the transfer charger 4 toward the photosensitive drum 1 during the transfer process was reduced, and only a recorded image in which an image was missing due to unstable transfer could be obtained.

(Problems to be Solved by the Invention) As described above, in the above-described conventional electrophotographic recording apparatus, since the conveyance small-diameter rubber roller that is grounded is disposed very close to the transfer charger, the transfer from the transfer charger during the transfer process is performed. Much of the transfer current flows in the direction of the small-diameter rubber roller, and the current flowing in the direction of the photosensitive drum is reduced more than necessary. As a result, unstable transfer with image loss occurs, and there is a problem that recording quality is inevitable. Was.

The present invention has been made in view of the above-described circumstances, and can prevent image omission at the time of transfer due to a phenomenon in which a transfer current flows in the direction of a small-diameter rubber roller that is grounded and conveyed, thereby contributing to an improvement in image quality of a recorded image. An object of the present invention is to provide an electrophotographic recording device.

[Structure of device]

(Means for Solving the Problems) An electrophotographic recording apparatus according to the present invention comprises: an image carrier for carrying an electrostatic latent image corresponding to an image signal and a toner image developed from the electrostatic latent image;
Transfer charging means for transferring the toner image to the front surface of the recording paper while applying a charge from the back surface thereof, and a transfer charging means provided in close proximity to the image carrier and the transfer charging means for auxiliaryly transferring the recording paper immediately before the transfer position. The transfer small-diameter roller, which is grounded so as not to carry the charge related to the transfer while being transferred to the transfer, and the upper portion of the case side on the recording paper entry side of the transfer charging unit is bent at a substantially right angle to the case opening side. An insulator provided above and below the provided bent portion, and a wire electrode of the transfer charging means and the transport small-diameter roller extending from the insulator and projecting a predetermined length inward of the case opening. And an insulating member that is provided upright to a predetermined height position that separates them.

(Operation) In the electrophotographic recording apparatus of the present invention, the insulating member extending from the insulator provided at the bent portion of the transfer charging means causes the flow of the transfer current from the transfer charging means toward the conveying small-diameter roller in the transfer process. Acts to regulate.

As a result, the transfer current interruption function in the direction of the small-diameter roller is completely completed, and a high-quality recorded image without image omission can be obtained through a stable transfer process by supplying a sufficient transfer current in the direction of the image carrier. It becomes possible.

In particular, in the present invention, due to the structure of the insulating member that is attached so as to cover the protruding portion of the end portion of the recording paper entry side case of the transfer charging means, the insulating member is provided without performing special processing on the case of the transfer charging means. It can be provided, and the mounting work is extremely simple. Moreover, the structure of the insulating member that covers the projecting portion of the case end of the recording paper entry side of the transfer charging means realizes a structure in which the insulating member is also provided on the surface of the case projecting portion that faces the conveying small-diameter roller side. With this structure, even when the trailing end of the recording paper separates from the conveying small-diameter roller and comes into contact with the case protrusion, it is possible to reliably prevent the charge from escaping from the back surface of the recording paper.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 conceptually shows a configuration of a main part of an electrophotographic recording apparatus according to an embodiment of the present invention.

In FIG. 1, a photosensitive drum 1, a developing device 2, a recording paper 3, a transfer charger 4, an insulator 5, a small-diameter rubber roller 6 for conveyance,
The slip ring 7, the registration rollers 8a and 8b, and the registration guide 9 fulfill the same functions as those of the conventional apparatus shown in FIG.

That is, the photosensitive drum 1 rotates while carrying an electrostatic latent image corresponding to an image signal formed on the peripheral surface thereof during the exposure process.

The developing device 2 adheres a developer to the electrostatic latent image formed on the peripheral surface thereof in accordance with the rotation of the photosensitive drum 1 and develops the electrostatic latent image as a toner image.

The recording paper 3 is supplied by a registration roller 8 (8a, 8b) through a registration guide 9, and further reaches the photosensitive drum 1 while being supplementarily conveyed by a conveyance small-diameter rubber roller 6, and thereafter is wound around the peripheral surface thereof. To enter the transfer position direction.

The transfer charger 4 transfers the toner image from the peripheral surface of the photosensitive drum 1 to the surface of the recording paper 3 by applying corona discharge from the back surface of the recording paper 3 that is wound around and conveyed around the photosensitive drum 1.

The insulator 5 is one of the functions for suppressing the deterioration of the image quality, and interrupts the transfer current so that the transfer current does not concentrate on the protrusion on the upper side of the case of the transfer charger 4 on the side of the recording paper 3 in the transfer process.

The conveying small-diameter rubber roller 6 has a function of maintaining the recording paper 3 in a desired position at the transfer position in addition to auxiliary conveying of the recording paper 3 as described above, and includes the photosensitive drum 1 and the transfer charger 4.
It is attached in a state close to.

The slip ring 7 attached to the transport small-diameter rubber roller 6 is also one of the functions for suppressing the deterioration of image quality. During the execution of the above-described electrophotographic recording process, the transport small-diameter rubber roller 6 is the same as the electrode of the transfer charger 4. Polarized,
The conveying small diameter rubber roller 6 is grounded to attract the toner image before the recording paper 3 is wound around the photosensitive drum 1 and to prevent scattering of the image or stop of the machine due to leakage.

In the electrophotographic recording apparatus of the present invention, in addition to these mechanisms, an insulating member 10 is provided at an end of the transfer charger 4 on the recording paper 3 entry side at the upper part of the case.

As shown in FIG. 1, the position at which the insulating member 10 is disposed is a position separating the electrode of the transfer charger 4 from the small-diameter transport roller 6 provided near the electrode.

Further, the shape is clarified by a detailed configuration diagram shown in FIG.

In FIG. 2, the insulating member 10 is a tongue-shaped member that extends from the insulator 5 to cover the small-diameter rubber roller 6 to be conveyed at the upper end of the transfer charger 4 on the case where the recording paper 3 enters.

In such a configuration, the ability to cut off the transfer current flowing from the transfer charger 4 toward the conveying small-diameter rubber roller 6 is enhanced as compared with the insulator 5 that only partially covers the upper part of the case of the transfer charger 4.

In the conventional apparatus having only the insulator 5, the transfer small-diameter rubber roller 6, which is grounded, is located near the upper part of the case of the transfer charger 4, so that the transfer current flowing from the transfer charger 4 to the roller cannot be sufficiently shut off. Inevitably, the transfer current flowing in the direction of the photosensitive drum 1 was reduced, and image missing was likely to occur.

In the apparatus according to the present invention, the transfer current flowing from the transfer charger 4 toward the conveying small-diameter rubber roller 6 can be efficiently cut off by the newly provided insulating member 10, and the transfer current flowing toward the photosensitive drum 1 can be maintained at a sufficient level. It is possible to perform stable transfer without image omission.

For example, according to an experiment conducted by the inventor of this apparatus, if the height H (see FIG. 2) of the insulating member 10 is 3 mm, the transfer current flowing from the transfer charger 4 toward the photosensitive drum 1 is conveyed. It has been confirmed that a current level comparable to that when the small-diameter rubber roller 6 is floated can be obtained.

[Effect of the invention]

As described above, according to the present invention, the upper portion of the case side on the recording paper entry side of the transfer charging means is bent substantially at right angles to the case opening side, and the insulation provided over the bent portion is provided. And an insulating member extending from the insulator and standing up to a predetermined height position separating the wire electrode of the transfer charging means and the conveying small-diameter roller at a position protruding a predetermined length inward of the case opening. Since a is provided, a: by appropriately determining the length and height of the protrusion of the insulating member from the insulator, the flow of the transfer current from the transfer charging unit toward the conveying small-diameter roller can be reliably blocked, and the transfer member can be moved toward the image carrier. Thus, it is possible to obtain a high-quality recorded image without image loss by suppressing a decrease in the transfer current.

b. The above structure in which an insulator is provided above and below the bent portion of the transfer charging means also has a structure in which an insulator is also provided on the surface of the bent portion of the transfer charging means facing the side of the small-diameter roller. With this structure, even if the trailing edge of the recording paper comes into contact with the bent portion after the trailing edge of the recording paper separates from the small-diameter roller, the back surface charge of the recording paper can be reliably held to prevent image disturbance.

 And so on.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing a main configuration of an electrophotographic recording apparatus according to an embodiment of the present invention. FIG. 2 is an enlarged view showing a configuration of an insulating member 10 in the electrophotographic recording apparatus of FIG. FIG. 3 is a conceptual diagram showing a general configuration of a conventional electrophotographic recording apparatus of this kind. 1 photosensitive drum, 2 developing device, 3 recording paper, 4
... Transfer charger, 5 ... Insulator, 6 ... Conveying small diameter rubber roller, 7 ... Slip ring, 8a, 8b ... Registration roller, 9 ... Registration guide, 10 ... Insulating member

 ──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-58-91479 (JP, A) JP-A-64-13571 (JP, A) JP-A-63-212973 (JP, A) JP-A-63-12973 210978 (JP, A) JP-A-62-94879 (JP, A) JP-A-63-124262 (JP, U) JP-A-55-169538 (JP, U) JP-A-1-135456 (JP, U) JP-B-58-36336 (JP, B2) JP-B-60-39867 (JP, Y2)

Claims (1)

(57) [Scope of request for utility model registration] An image bearing member for carrying an electrostatic latent image corresponding to an image signal and a toner image developed from the electrostatic latent image; and a transfer for transferring the toner image from the back surface of the recording paper to the surface thereof while applying a charge. A charging means, a transfer small diameter which is provided in proximity to the image carrier and the transfer charging means, and which is auxiliaryly conveyed to the recording sheet immediately before the transfer position, and is grounded so as not to take charge related to the transfer. A roller, an insulator provided above and below a bent portion which is formed by bending an upper portion of the side surface of the case on the recording paper entry side of the transfer charging unit at a substantially right angle to the case opening side, and extending from the insulator. An insulating member which is provided upright to a predetermined height position separating the wire electrode of the transfer charging means and the small-diameter transport roller at a position protruding a predetermined length inward of the case opening. Electrophotographer Apparatus.