JP3242291B2 - Electrophotographic recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic recording apparatus for performing both development and recovery of undeveloped developer in a developing means.

[0002]

2. Description of the Related Art In recent years, in order to reduce waste of toner, a cleanerless type of electrophotographic recording apparatus has been developed in which untransferred toner is collected in a developing apparatus and reused.

In such an electrophotographic recording apparatus, toner is collected by attracting toner adhering to a photoreceptor to a developing roller side of a developing device.

[0004]

Since the toner once carried on the developing roller is attracted to the developing roller by electrostatic force or the like, it is difficult to separate from the developing roller. Will be used immediately in the developing operation.

[0005] Incidentally, the toner carried on the developing roller is greatly subjected to mechanical stress due to contact with a photoreceptor or the like. The collected toner is carried on the developing roller before it adheres to the photoreceptor and for a long time after being collected. Therefore, the collected toner is more concentrated than the toner that has not been carried on the developing roller. Mechanical stress, resulting in significant deterioration. Since the deteriorated toner is preferentially used for development, the image quality is deteriorated regardless of a large amount of toner that has hardly deteriorated. There was a defect.

The present invention has been made in view of such circumstances, and an object of the present invention is to prevent a part of the developer from intensively deteriorating, thereby achieving good image quality. An object of the present invention is to provide an electrophotographic recording apparatus capable of stably continuing recording for a long period of time.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above objects, the present invention provides a photosensitive member, charging means for charging the surface of the photosensitive member to a predetermined charging potential, and charging by the charging means. Exposure means for irradiating the surface of the photoreceptor with light according to an image to be recorded to form an electrostatic latent image corresponding to the image, and a developing roller or the like in contact with the surface of the photoreceptor A developer supply member that is in contact with the developer support member, such as a supply roller, is supplied by the developer supply member, is carried by the developer support member, and has the same potential as the charging potential. Developing means for forming a developer image corresponding to the electrostatic latent image formed by the exposure means by adhering a developer charged to a polarity to the surface of the photoconductor; and developing means on the surface of the photoconductor. Developer formed by Transfer means for transferring the developer image onto a predetermined recording medium, a conductive brush slidably contacting the surface of the photoconductor after passing through a transfer position by the transfer means, and the developer image is formed on the surface of the photoconductor. When the conductive brush passes through a position where the conductive brush slides on the area, a predetermined suction voltage lower than the surface potential of the photoconductor is applied to the conductive brush, and the developer image is formed on the surface of the photoconductor. When the conductive brush slidably contacts a predetermined area where no ink is formed, a predetermined discharge voltage higher than the surface potential of the photoreceptor is applied to the conductive brush. For example, a suction bias power supply, a discharge bias Power supply,
A disturbing unit having a power supply unit including a switch and a recording control unit; and a region passing through a position where the conductive brush slides when the discharging voltage is applied to the conductive brush is formed by the developer carrier. A developer supply unit potential lowering unit including, for example, a switch and a recording control unit for making the potential of the developer supply unit lower than the potential of the developer carrier during a period of passing the contact position.

[0008]

By taking such measures, the electrostatic latent image formed on the photoreceptor is developed using the toner supplied from the developer supply member to the developer carrying member. The transferred toner image is transferred to a predetermined recording medium by a transfer unit to record an image, but the developer remaining on the photoreceptor without being transferred to the recording medium is collected by a conductive brush of a disturbance unit. Is done. The developer collected by the conductive brush is discharged to an area of the photoconductor that is not used for recording an image, and is collected by the developer carrier. As described above, when the developer carrying member collects the developer, the potential of the developer supplying member is made lower than the potential of the developer carrying member by the developer supplying member potential lowering means. The developer recovered by the developer carrier is further recovered by a developer supply.

Therefore, the developer recovered by the developer carrier is prevented from being continuously carried on the developer carrier.

[0010]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a main configuration of an electrophotographic recording apparatus according to this embodiment. In the figure, reference numeral 1 denotes a drum-shaped photosensitive member formed of a positively charged organic material, which is rotated in a direction indicated by an arrow by a rotation driving device (not shown). Around the photosensitive member 1, a charging device 2, an exposing device 3, a developing device 4, a transfer device 5, a static eliminator 6, and a toner disturbing device 7 are provided along the peripheral surface on the downstream side in the rotation direction of the photosensitive member 1. It is arranged in order toward.

The charging device 2 is of a so-called scorotron type comprising a charging high voltage power supply 21, a wire 22, a grid 23 and a zener diode 24. That is,
A high voltage (for example, +2
The surface of the photoreceptor 1 is charged by corona discharge generated by the wire 22 when a constant current is controlled to 00 μA. A grid 23 grounded via a zener diode 24 (e.g., 700 V) is arranged between the wire 22 and the photoreceptor 1 to make the surface potential of the photoreceptor 1 uniform at a predetermined potential (e.g., +670 V). Charges.

The exposure device 3 comprises, for example, an LED head and irradiates the surface of the photoreceptor 1 with light based on image data.
An electrostatic latent image corresponding to an image to be recorded is formed on the surface of the photoconductor 1.

The developing device 4 forms a toner image on the surface of the photoconductor 1 by adhering a non-magnetic one-component toner T on the surface of the photoconductor 1 in accordance with the electrostatic latent image formed by the exposure unit 3. Things. The developing device 4 includes a developing roller 42 that carries the toner T stored in the toner hopper 41 and comes into contact with the photoconductor 1, a supply roller 43 that supplies the toner T stored in the toner hopper 41 to the developing roller 42, A developing blade 44 for thinning the toner T carried on the developing roller 42 and frictionally charging the toner T to a positive polarity; and a developing bias power supply for applying a developing bias of a predetermined voltage (for example, +250 V) to the developing roller 42. 45, a supply bias power supply 46 for applying a supply bias of a predetermined voltage (for example, +350 V) to the supply roller 43, and a supply bias power supply 4
Switch 4 for selecting whether to connect or ground 6
7 are provided. The developing roller 42 and the supply roller 43 are respectively rotated in the illustrated arrow direction by a rotation driving device (not illustrated).

The transfer device 5 transfers the toner image formed on the surface of the photoconductor 1 by the developing device 4 to the recording paper P, and includes a transfer roller 51 in contact with the photoconductor 1,
A transfer bias power supply 52 for applying a transfer bias of a predetermined voltage (for example, -900 V) having a polarity (negative polarity) opposite to the charging potential of the photoconductor 1 to the transfer roller 51;
1, a predetermined voltage (for example, +
A cleaning bias power supply 53 for applying a transfer roller cleaning bias of 1000 V); and a switch 54 for turning on / off the bias application to the transfer roller 51 and selecting the transfer bias power supply 52 and the cleaning bias power supply 53. I have. The transfer roller 51
Is rotated in a direction indicated by an arrow by a rotation driving device (not shown).

The static eliminator 6 irradiates light over the entire width of the photoconductor 1 to lower the surface potential of the photoconductor 1.

The toner disturbance device 7 is constructed by implanting a large number of bristles 71b made of a conductive material around a shaft 71a.
The hair 71 has a predetermined resistance value (for example, about 10 ⁶ Ω).
b, a conductive roller member 71 whose leading end is in contact with the surface of the photoreceptor 1, a suction bias power supply 72 for applying a suction bias of a predetermined voltage (for example, -300 V) to the conductive roller member 71, A discharge bias power supply 73 for applying a discharge bias of a predetermined voltage (for example, +300 V) to the conductive roller member 71, and a bias power supply 7 for ON / OFF of bias application to the conductive roller member 71 and suction.
2 and a switch 74 for selecting the ejection bias power supply 73. Reference numeral 8 denotes a recording control unit which controls operations of a transfer bias power supply 52, switches 47, 54, and 74, other bias power supplies, and a rotation driving device for each roller.

Next, the operation of the electrophotographic recording apparatus configured as described above will be described. First, the surface of the photoconductor 1 is uniformly charged to +670 V by the charging device 2 and then exposed by the exposing device 3 in accordance with image data to form an electrostatic latent image. At this time, the surface potential of the photoconductor 1 is, for example, approximately 80
V, and the area where light was not irradiated, that is, the area of the white image becomes 650 V, for example, due to dark decay.

Subsequently, a developing device 4 is provided on the surface of the photoreceptor 1.
As a result, the toner T adheres in accordance with the electrostatic latent image to form a toner image. Specifically, in the developing device 4, a toner T charged to the same polarity (positive polarity) as the charged potential of the photoconductor 1 is carried on the developing roller 42, and the toner T is brought into contact with the photoconductor 1. A developing bias having the same polarity as the charging potential of the photoconductor 1 (potential of the unexposed area) and a low voltage (for example, +250 V) is applied to the developing roller 42 from a developing bias power supply 45. Of the photoreceptor 1
Is selectively adhered to the toner T. That is, the photoconductor 1
The toner T does not adhere to the upper charged portion because the photoconductor 1 side is at a high potential, and the photoreceptor 1 is exposed to the portion where the potential is reduced by exposure, as shown in the toner suction area in FIG.
Since the side has a low potential, the toner T adheres.

The toner T thus adhered to the photoreceptor 1 is transferred to the recording paper P by the transfer device 5. Specifically, during the recording operation (when transfer processing is necessary), the switch 54 is controlled by the transfer bias power supply 5 under the control of the recording control unit 8.
2, the transfer roller 51 is applied with a transfer bias having a polarity opposite to the charging polarity of the photosensitive member 1 and the toner T generated by the transfer bias power supply 52. Due to the electric field generated between the photoconductor 1 and the transfer roller 51 by the transfer bias, the toner T adhered to the surface of the photoconductor 1
Is transferred onto the recording paper P which is nipped and conveyed between the photoconductor 1 and the transfer roller 51.

However, it is difficult for the transfer device 5 to completely transfer all of the toner T adhered to the photosensitive member 1 to the recording paper P, and 10 to 20% of the toner T remains on the photosensitive member 1. When the recording paper P comes into contact with the photoreceptor 1, paper powder S adheres to the surface of the photoreceptor 1. The toner T and the paper dust S that have passed through the contact position between the photosensitive member 1 and the transfer roller 51 while adhering to the photosensitive member 1 in this manner.
Reaches the conductive brush roller 71. In addition, while reaching the contact position with the conductive brush roller 71 from the contact position (transfer position) of the transfer roller 51, the surface of the photoconductor 1 is irradiated with light from the static eliminator 6 so that the surface potential of the photoconductor is sufficient. (For example, +50 V).

The conductive brush roller 71 is rotationally driven by a rotary driving device, and the bristles 71b slide on the surface of the photoreceptor 1. Therefore, the bristle 71b of the conductive brush roller 71 removes and holds the paper dust S attached to the surface of the photoconductor 1. As a result, the paper dust S adhered to the surface of the photoconductor 1 in the transfer process is removed from the surface of the photoconductor 1. Paper powder S
Since the toner is not as closely adhered to the photoconductor 1 as the toner T, it can be removed from the photoconductor 1 by the sliding contact of the conductive brush roller 71.

In the toner disrupting device 7, at least the recording area of the photoreceptor 1 (the area used for image recording regardless of exposure / non-exposure) is a conductive brush roller 71.
The switch 74 selects the bias power supply 72 for suction under the control of the recording control unit 8, as shown in FIG.
That is, the conductive brush roller 71 has, for example, −30.
A bias for suction of 0 V is applied. Therefore, if the toner T attached to the photoreceptor 1 remains positive, the surface potential of the attached position of the toner T of the positive polarity becomes higher than the potential of the conductive brush roller 71, The toner T is sucked toward the conductive brush roller 71 as shown in a toner suction area in FIG. In addition, for the toner T whose polarity has been inverted to the negative polarity due to the influence of the transfer bias, the surface potential at the attachment position is lower than the potential of the conductive brush roller 71, and therefore, the toner T is a photosensitive member. It passes through the contact position of the conductive brush roller 71 while being adhered to 1.

The negative polarity toner T that has passed through the contact position of the conductive brush roller 71 while being adhered to the photoreceptor 1 is again inverted in polarity by the charging device 2 to the positive polarity. Reaches the contact position. At this time, if light is applied to the area where the toner T is adhered, the toner T charged to the positive polarity is attracted to the photoconductor 1 side and the photoconductor 1 is directly applied to the photoconductor 1 according to the development principle described above. If the remaining area and the area where the toner T is adhered are not irradiated with light, the positively charged toner T
Is attracted to the developing roller 42 side and is collected by the developing device 4. Incidentally, the amount of the toner T whose polarity is inverted to the negative polarity due to the influence of the transfer bias is very small.
Therefore, since the exposure by the exposure device 3 is not hindered, no positive / negative memory is generated.

If the paper dust S left on the conductive brush roller 71 adheres to the photoreceptor 1, it is collected by the developing roller 42 together with the toner T. However, even if the paper dust S is mixed into the developing device 4, the toner T does not prevent the toner T from being charged because the toner T has the positive polarity. Therefore, it is possible to avoid various problems caused by the presence of the paper dust S.

Most of the transfer residual toner charged to the positive polarity is collected by the conductive brush roller 71 during the recording operation. The toner T collected by the conductive brush roller 71 in this way is returned to the photoconductor 1 when the non-recording area of the photoconductor 1 passes through the contact position with the conductive brush roller 71.

That is, the period from the start of the operation to the toner suction period and the period from the end of the toner suction period to the stop of the operation are each a toner discharge period. During this toner discharge period, the switch 74 is turned on to the suction bias power supply 72 under the control of the recording control unit 8 as shown in FIG. From +300
A bias for suction of V is applied. Thus, for the toner T (positive polarity) collected by the conductive brush roller 71, the potential on the photosensitive member 1 side becomes lower than that of the conductive brush roller 71, and as shown in the toner collecting region in FIG. It is sucked to one side. Therefore, the toner T held by the conductive brush roller 71 is returned to the surface of the photoconductor 1.

The toner T returned to the surface of the photoconductor 1 is sufficiently charged to a positive polarity by the charging device 2 and then reaches a contact position between the photoconductor 1 and the developing roller 42. At this time, since the exposure by the exposure device 3 is not performed, the surface potential of the photoconductor 1 when it reaches the contact position with the developing roller 42 is the charging potential, and the toner T adhering to the photoconductor 1 is charged.
(Positive polarity), the developing roller 42 has a lower potential, and as shown in the toner collecting area in FIG.
Is attracted to the developing roller 42 side and is collected by the developing device 4.

The recording control unit 8 controls the conductive brush roller 7 during the toner suction period on the surface of the photosensitive member 1.
In the period during which the area passing through the contact position with the developing roller 42 passes through the contact position of the developing roller 42, that is, a point on the surface of the photoconductor 1 is moved from the contact position with the conductive brush roller 71 to the contact position of the developing roller 42. A period delayed from the toner suction period for a time TA required to move the toner supply period to a predetermined time TA is defined as a toner supply period as shown in FIG. The recording controller 8 causes the switch 47 to select the supply bias power supply 46 during the toner supply period,
A supply bias of 350 V is applied. Thus,
For the toner T charged to the positive polarity, the developing roller 42
3 has a lower potential than the supply roller 43 side.
The toner is supplied from the supply roller 43 to the developing roller 42 as shown in the toner suction area in FIG.

On the other hand, the recording control unit 8 controls the period from the start of operation to the toner supply period and the period from the end of the toner supply period to the stop of the operation, that is, the toner on the surface of the photosensitive member 1. In the ejection period, a period in which a region passing through the contact position with the conductive brush roller 71 passes through the contact position with the developing roller 42 is defined as a toner collection period as shown in FIG. Then, the recording controller 8 causes the switch 47 to ground the supply roller 43 during the toner collection period. Thus, for the toner T charged to the positive polarity, the supply roller 43 side has a lower potential than the developing roller 42 side, and the toner T collected by the developing roller 42 as shown in the toner collecting area in FIG. Further, it is collected by the supply roller 43.

The toner T collected by the supply roller 43
Is separated from the supply roller 43, returned into the toner hopper 41, and mixed with unused toner. Here, since the supply roller 43 is grounded, the force for holding the toner T on the supply roller 43 is very weak, and the toner T collected by the supply roller 43 is separated from the supply roller 43 very easily.

As described above, according to the present embodiment, the toner T collected from the surface of the photoconductor 1 by the developing roller 42 is
Furthermore, the toner hopper 4
Since the toner T is mixed with the toner T in the portion 1, a part of the toner T is intensively used for development. This prevents some of the toner T from intensively deteriorating, and stable development can be continued for a long period of time.

The present invention is not limited to the above embodiment. For example, in the above embodiment, the supply roller 43 is grounded in order to make the potential of the supply roller 43 lower than the potential of the developing roller 42, but a voltage lower than the developing bias may be applied. However, it is preferable that the absolute value of the voltage be as low as possible.

In the above-described embodiment, the electrophotographic recording apparatus to which the developing device 4 of the contact developing system using the non-magnetic one-component toner T is applied is illustrated, but a developing device of another developing system is applied. The present invention can be applied to an electrophotographic recording device.

The specific structure of the photosensitive member 1, the charging device 2, the exposing device 3, the transfer device 5, the charge removing device 6, the toner disturbing device 7, and the like is not limited to those exemplified in the above embodiment.

In addition, various modifications can be made without departing from the gist of the present invention.

[0037]

According to the present invention, a photosensitive member, charging means for charging the surface of the photosensitive member to a predetermined charging potential, and recording on the surface of the photosensitive member after being charged by the charging means. Exposure means for irradiating light in accordance with an image to be formed to form an electrostatic latent image corresponding to the image, a developer carrier such as a developing roller in contact with the surface of the photoconductor, and the developer carrier A developer roller, for example, a supply roller, which is in contact with the photosensitive member; a developer supplied by the developer supply member, carried by the developer carrier, and charged to the same polarity as the charging potential; A developing unit that forms a developer image corresponding to the electrostatic latent image formed by the exposing unit by attaching the developing unit to the surface of the photoconductor; Transfer hands to transfer to recording media And a conductive brush that slides on the surface of the photoconductor after passing through a transfer position by the transfer unit, and the conductive brush slides on a region of the surface of the photoconductor where the developer image is formed. When passing through the position, a predetermined suction voltage lower than the surface potential of the photoconductor is applied to the conductive brush, and the predetermined area of the surface of the photoconductor where the developer image is not formed is When the conductive brush comes into sliding contact, a predetermined discharge voltage higher than the surface potential of the photoconductor is applied to the conductive brush, for example, a power supply including a suction bias power supply, a discharge bias power supply, a switch, and a print control unit. And a region passing through a position where the conductive brush slides when the discharge voltage is applied to the conductive brush. A developer supply member potential lowering means including, for example, a switch and a recording control unit for lowering the potential of the developer supply member to be lower than the potential of the developer carrier during a period in which the holding member passes through the contact position. In addition, it is possible to prevent an intensive deterioration of a part of the developer, thereby providing an electrophotographic recording apparatus capable of stably continuing recording with good image quality for a long period of time.

[Brief description of the drawings]

FIG. 1 is a diagram showing a main configuration of an electrophotographic recording apparatus according to one embodiment of the present invention.

FIG. 2 is a diagram showing operation timings of respective units during a recording operation in the electrophotographic recording apparatus shown in FIG.

FIG. 3 is a diagram schematically showing a relationship between potentials of respective portions and a moving state of toner when two all-black images are recorded by the electrophotographic recording apparatus shown in FIG. 1;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photoconductor 2 charging device 3 exposure device 4 developing device 42 developing roller 43 supply roller 46 supply bias power supply 47 switch 5 transfer device 6 static eliminator 7 toner disturber 71 conductive brush Roller 72: bias power supply for suction 73: bias power supply for ejection 74: switch 8: recording controller T: toner P: recording paper

Claims (1)

(57) [Claims] 1. A photoreceptor, charging means for charging the surface of the photoreceptor to a predetermined charging potential, and charging the surface of the photoreceptor after charging by the charging means in accordance with an image to be recorded Exposure means for irradiating light to form an electrostatic latent image corresponding to the image, a developer carrier in contact with the surface of the photoconductor, and a developer supply body in contact with the developer carrier Having, supplied by the developer supply member and carried by the developer carrier,
A developing unit that forms a developer image corresponding to an electrostatic latent image formed by the exposure unit by attaching a developer charged to the same polarity as the charging potential on the surface of the photoconductor; Transfer means for transferring a developer image formed on the surface by the developing means to a predetermined recording medium, and the photoconductor after passing through a transfer position by the transfer means
A charge removing means for lowering the surface potential of the photosensitive member to a predetermined potential, and a conductive brush slidably in contact with the surface of the photoreceptor after the surface potential is reduced by the charge removing means, and the developer image is formed on the surface of the photosensitive member. When the conductive brush passes through a position where the conductive brush slides on the formed area, a predetermined suction voltage lower than the surface potential of the photoconductor is applied to the conductive brush, and the developing brush is formed on the surface of the photoconductor. Disturbing means having a power supply means for applying a predetermined discharge voltage higher than the surface potential of the photoconductor to the conductive brush when the conductive brush is in sliding contact with a predetermined area where no agent image is formed, In a period in which the region passing through the position where the conductive brush slides when the discharge voltage is applied to the conductive brush passes through the position where the developer carrier is in contact, And a developer supply unit potential lowering unit that makes the potential of the developer supply unit lower than the potential of the developer carrier during a period in which the photoconductor is not irradiated with light by the exposure unit. An electrophotographic recording device characterized by the above-mentioned.