JPH0387761A - Drum unit - Google Patents

Abstract

PURPOSE:To adjust electrifying and other conditions without removing a drum unit from a device main body and to make the unit compact by concentratingly arranging adjusting mechanisms required for controlling the unit around at the end of the drum unit of an electrophotographic recorder main body. CONSTITUTION:An electrifier 31, a developing roller 63, a transfer unit 61, and a cleaning member consisting of a cleaning blade 51 and a carrying screw 53 are concentratingly arranged around the photosensitive drum 15. The electrifier 31 is so constituted that a corona wire 35 is stretched in a shield case possessing a grid part 37, and all of the drum 15, the electrifier 31, the cleaning member 51 and the carrying screw 53 are enclosed by a unit case 11, with a part of the drum 15 left. The drum unit is constituted in such a way. Thus, adjustment after the drum unit is loaded to the recorder main body is possible, and the unit can be made compact.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a drum unit in an electrophotographic recording device.

In electrophotographic recording devices such as copying machines and laser beam printers, the entire surface of the photoreceptor is generally charged using a corona discharger, and an electrostatic latent image is formed by image exposure using an optical system. It is developed to form a toner image, transferred to paper or the like, and then fixed. Furthermore, the toner remaining on the photoreceptor after transfer is cleaned, and the photoreceptor is again prepared for image recording, while the cleaned toner is transported and collected.

Each functional unit such as an optical system, a fixing system, and the vicinity of a photoreceptor is formed into a unit. A corona discharger, a developing roller, a transfer device, a cleaning member, and a toner conveying screw are arranged around the photoreceptor drum so as to surround the photoreceptor drum.

Generally, at least a photosensitive drum and a corona discharger are integrated to form a drum unit, and a cleaning member, a toner conveying screw, or a developing member may also be integrated. This drum unit) is installed and used by being inserted into the main body of the electrophotographic recording apparatus.

As the electrophotographic recording apparatus is used, the charged state of the photoreceptor drum may change, or it may be necessary to change the toner conveyance and discharge capabilities. In such a case, it is necessary to adjust the distance between the corona discharge electrode and the photosensitive drum, or to change the rotational speed of the toner conveying screw.

Conventionally, the adjustment points necessary for braking the drum unit were not arranged in one place on the drum unit. Therefore, when making adjustments, it is necessary to pull out the unit from the main body of the device, and in some cases, adjustments cannot be made without disassembling the unit.

In addition, since the unit is supposed to be inserted and removed, a handle structure is provided on the unit cover.
As a result, the cover became larger and the entire unit also became larger.

SUMMARY OF THE INVENTION It is an object of the present invention to enable adjustments after the drum unit is installed in the apparatus main body, and to make the unit more compact as a whole.

The drum unit of the present invention includes an electrophotographic photoreceptor and a corona discharger for charging the photoreceptor, and is mounted integrally on an electrophotographic recording device; Near the end of the unit on the front side, there is a discharge voltage adjustment mechanism for the corona discharger, and the distance between the discharge wire electrode of the discharger and the electrophotographic photoreceptor. I
It is characterized in that the adjustment mechanisms necessary for braking the units, such as the I mechanism and the rotational speed adjustment mechanism of the toner conveying screw of the cleaning member, are centrally arranged.

FIG. 1 is a schematic diagram showing the vicinity of a drum unit according to an embodiment of the present invention.

As shown in FIG. 1, a cleaning member consisting of a charging device 31, a developing roller 63, a transfer device 61, a cleaning blade 51, and a conveying screw 53 is arranged around the photosensitive drum 15. The charger 31 includes a corona wire 35 (discharge electrode) stretched inside a shield case 23 having a grid portion 37. The photoreceptor drum 15, the charger 31, and the cleaning member (51+53) are surrounded by the unit case 11, leaving a part of the photoreceptor drum 15, to form a drum unit.

When recording electrophotography, the photoreceptor drum 15 is connected to the charger 3.
1, the entire surface is charged, and an image is exposed by an optical system 65 such as a laser scanning system 5 to form an electrostatic latent image, which is transferred to a developing roller 63.
to form a toner image on the photoreceptor drum 15, this toner image is transferred to paper by a transfer device 61, and after the transfer, the toner remaining on the photoreceptor drum 15 is removed by the cleaning blade 51. Toner conveying screw 53
It is discharged by When assembling the drum unit,
The discharge voltage is adjusted and set so that the surface of the photoreceptor drum 15 is charged to an appropriate level.

The distance between the surface of the photosensitive drum 15 and the corona wire 35 is adjusted and set. Furthermore, the toner discharge capacity, that is, the rotational speed of the conveying screw 53 is also set to an appropriate value.

However, if the printer is attached to a laser beam printer and the number of copies printed increases, the setting may deviate from the appropriate setting level, and readjustment is required after installation.

FIG. 2 is an external view (plan view) of the drum unit of the present invention.
The drum unit, in which the photoreceptor drum 15 and the like are surrounded by the unit case 11, is inserted into the apparatus main body in the direction of arrow A in the figure. Therefore, after installation,
The drum unit cover ■3 will be attached to the front.

FIG. 3 is a partially enlarged view showing the vicinity of the cover of the drum unit. Figure 3 shows the upper part of the drum unit cut away, and the lower half of the figure shows an even larger cutout of the upper part of the drum unit (gears 19, 23, 57 are not shown). , is a schematic view showing the main components, taken in cross section at a position corresponding to line IV-IV in FIG. 3;

When the cover 13 is removed, each adjustment mechanism is located at that position. By inserting a Mylar film into the gap 39, the entire shield case 33 can be pushed up in the drum separation direction. By adjusting the thickness and number of mylar films, the distance between the corona wire 35 stretched inside the shield case 33 and the surface of the photoreceptor drum 15 can be adjusted. In addition, a volume (variable resistor, etc.) for adjusting the discharge voltage is provided in the volume hole 41.
Since this is commonly used, the surface potential of the photoreceptor drum 15 can be adjusted by turning it with a driver or the like.

When the photosensitive drum 15 rotates during printing, a drum gear 19 attached to the drum shaft 17 rotates. This rotation is transmitted to the screw gear 57 by the transmission gear 23, the conveyance screw 53 connected to the screw shaft 55 rotates, and the toner is discharged. Therefore, gears 19, 23,
By adjusting the gear ratio of 57, the conveying screw 5
By changing the rotation speed of No. 3, it is possible to improve the toner discharging ability. The gears 19, 23, 57 can be easily replaced by removing the cover 13.

In this way, all the adjustment mechanisms are located in the space inside the cover, so once the cover is removed, adjustments can be made while the drum unit is still installed in the device body. Since the space is effectively used as a place for arranging the adjustment mechanism, the drum unit as a whole can be made smaller, and the main body of the apparatus can also be made smaller.

In the above embodiment, the drum unit is composed of a photoreceptor drum, an IF electric device, and a cleaning member, but it may be formed by only the drum photoreceptor and a charging device, or by adding a developing device.

According to the present invention, the adjustment mechanism necessary for controlling the drum unit, which is used in an electrophotographic recording device, is concentrated near the end of the unit on the front side in the direction of the device. By the way.

It is possible to adjust charging conditions, etc. without removing the unit from the main body of the device, and moreover, it is possible to realize compactness.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the vicinity of the drum unit. FIG. 2 is a plan view showing the entire drum unit. FIG. 3 is a cutaway view showing the vicinity of the cover of the drum unit, and FIG. 4 is a sectional view. 11...Unit case E3...Cover 15...
・Photosensitive drum 17...Drum shaft 19...Drum gear 21...Transmission shaft 23...Transmission gear
31... Charger 33... Shield case 35
...Corona wire 37...Grid part 39.
...Gap portion 41...Volume hole 51...Cleaning blade 53...Transportation screw 55...Screw shaft 57
...Screw gear

Claims (1)

[Scope of Claims] 1. In a drum unit that includes at least an electrophotographic photoreceptor and a corona discharger for charging the photoreceptor and is mounted integrally on the main body of an electrophotographic recording device; mounting on the main body of the electrophotographic recording device A drum unit characterized in that an adjustment mechanism necessary for braking the unit is concentrated near an end of the drum unit on the front side in the direction. 2. The adjustment mechanism is a discharge voltage adjustment mechanism of the corona discharger;
2. The drum unit according to claim 1, which is a mechanism for adjusting the distance between a discharge wire electrode of a corona discharger and an electrophotographic photoreceptor. 3. The drum unit according to claim 2, further comprising a cleaning member for collecting excess toner remaining on the photoreceptor after development, and a rotation speed adjusting mechanism for a toner conveying screw of the cleaning member as the adjusting mechanism.