JPS60125865A - Developing device - Google Patents

Abstract

PURPOSE:To adjust a gap corresponding to variance in photosenstive body performance, etc. by allowing the outer circumference of a guide roller supported coaxially with a developing roller to abut on tapered guide parts at both shoulders of a photosensitive body. CONSTITUTION:Guide rollers 11a and 11b are provided coaxially at both sides of the developing roller 10 supported pivotally on bearings 14a and 14b, and its outer circumferential tapered surface abuts on tapered guide parts 7a and 7b of the photosensitive body 6. A lock nut 16 is loosened and the bearings whose outer diameter parts are thread-cut are rotated to move their positon forward, and then the rollers 11 also move axially with the energizing force of a spring 13 to vary the gap 30 between the photosensitive body 6 and roller 10 according to deviation in the contact position with the tapered surfaces of the guide parts 7. The gas is adjusted finely by utilizing the rotations of the bearings 14. Therefore, even when there is variance in component precision and photosensitive body characteristics, the gap is adjustable and developing force is increased by reducing the amount of the gap.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a developing device used in copying machines, printers, etc. using electrophotographic technology.

In a developing device that forms a toner image on a photoreceptor according to the electrostatic latent image formed on the photoreceptor, there is a device that brings toner from a toner hopper and transfers it onto the photoreceptor. The gear wheel between the developing roller and the photoreceptor has a very large effect on the image quality after development. Conventionally, in order to keep the amount of gear lag constant at about 0.3 to 0.6 in, a configuration as shown in FIG. 1, for example, has been adopted.

Reference numeral 1 denotes a photoreceptor drum, and guide portions 2a and 2b having a constant diameter are provided at both ends of the photoreceptor drum. 3 is the developing roller,
On the other hand, guide rollers 4a and 4b are coaxially rotatably supported. The entire developing device 5 is biased toward the photoreceptor drum 1, and the guide portions 2a, 2 of the photoreceptor drum 1
The photosensitive drum 1 and the image roller 3 are rotated while the outer circumferences of the guide rollers 4a and 4b are in pressure contact with each other. The guide rollers 4a and 4b are rotated according to the rotation of the photoreceptor drum.

The gap d between the photoreceptor drum 1 and the developing roller 3 is determined by the relationship between the respective diameters of the photoreceptor drum 1 and its guide portions 2a, 2b, and the developing roller 3 and guide rollers 4a, 4b. The variation in the gap is within the range of the variation in the diameter difference between the outer diameter of the photoreceptor drum and the guide portion, and the variation in the diameter difference between the developing roller diameter and the guide roller, and is caused by the rotation of the entire photoreceptor drum 1 and the entire developing roller, etc. is not affected by Therefore, a relatively high precision gap can be maintained.

However, as mentioned above, the accuracy of the gap is affected by variations in the diameter of each part, so if a higher precision gap is required, adjustment is impossible and parts must be replaced. Or, if the developing performance of the developing device or the performance of the photoreceptor varies depending on the device due to the combination of parts,
After assembly, the gap cannot be adjusted and parts must be replaced.

Purpose of the Invention The present invention overcomes the above-mentioned drawbacks of the conventional example, and can form a gap with even higher precision, or finely adjust the gap in response to variations in developing performance and photoreceptor performance depending on the device. The purpose is to provide a developing device.

Composition of the Invention The present invention includes a photoreceptor drum, a developing roller facing the photoreceptor drum, a guide roller rotatably supported coaxially with the developing roller, and an outer periphery of the guide roller forming a part of the outer periphery of the photoreceptor drum. It has a biasing means for biasing the developing device so as to come into contact with a provided guide part, and either one or both of the guide part of the photoconductor and the outside of the guide roller is made into a tapered shape so that the photoconductor This allows minute adjustment of the gap between the drum and the developing roller.

DESCRIPTION OF EMBODIMENTS An embodiment in which a developing device according to the present invention is applied to an image forming method using transparent pE powder particles will be described below with reference to the drawings.

FIG. 2 is a plan view of the developing device according to the present invention, and FIG. 3 is a side view of the main parts thereof.

Reference numeral 6 denotes a photoreceptor drum, which is made of metal such as aluminum, and its outer peripheral surface, except for both ends, is coated with a photoreceptor such as zinc oxide or selenium. Both ends of the outer periphery are
As shown in Fig. 2, there are guide portions 7a and yb shaped like tenos whose diameter decreases toward the sides. Although the amount of these tenons is exaggerated in the drawing, in reality, for example, The photoreceptor drum 6 is as small as the side plate 8.
a.

It is pivotally supported by 8b. A gear 9 is integrally formed on one side of the photoreceptor drum 6, and is connected to and driven by a drive gear (not shown). A developing roller 10 is made of metal, and its outer peripheral surface is coated with a dielectric material such as polyester or polyvinylidene fluoride. Guide rollers 11a and 11b are provided on both sides of the developing roller 10.
are pivotally supported via bearings 12a and 12b (not shown). Also, the side surface of the developing roller 10 and the guide roller 11a
, 11b are provided with springs 13a and 13b, which bias the guide rollers 11a and 11b outward, respectively. The developing roller 1o has shaft portions at both ends, and bearings 14a are threaded on the outer diameter portion.

The bearing 14a is rotatably supported by the bearing 14b.

14b is a female screw portion 16a of the support plate 16, respectively.

16b. Further, the engagement between the bearings 14a, 14b and the female screw portions 16a, 16b of the support plate is locked by lock nuts 16a, 16b, respectively.

A gear 17 is integrally attached to one end of the developing roller 10 and engages with an intermediate gear 18 . Further, the intermediate gear 1 is coaxially formed integrally with the intermediate gear 18.
9. It is connected to the gear 9 of the photoreceptor drum 6 through the intermediate gear 20 . The bearings 21 of the intermediate gears 18 and 19 and the shaft 22 of the intermediate gear 20 are respectively implanted in the side plate 8a.

With the above configuration, as the photosensitive drum 6 is driven from the outside and rotates in the direction of the arrow 23, the developing roller is rotated in the direction of the arrow 24 at a constant rotational speed ratio according to the ratio of the number of teeth of each gear.

On the other hand, the support plate 16 supporting the developing roller section is rotatably supported by the side plates Ba and Bb by bins 26a and 25b planted at both lower ends. The support plate is the spring 26a, 2
6b, the entire developing roller portion is pressed toward the photoreceptor drum 6, and therefore the guide roller 11a.

The photosensitive drum 6 and the developing roller 1-0 rotate while the photosensitive drum guide portions 11b and the photosensitive drum guide portions 7a and 7b are in foil contact. Guide rollers 11a and 11b are guide portions 7a.

It rotates according to the rotation of the photoreceptor drum 6 due to friction with the photoreceptor drum 7b. On the other hand, a corona charger 27 is provided above and opposite the developing roller 1o, and is required to charge the outer peripheral surface of the developing roller 10 as it rotates. Further, a blade 28 is pressed against the outer circumferential surface of the developing roller to clean toner adhering to the outer circumferential surface, and the scraped off toner is collected in a toner receiver 29 .

The present embodiment has the above configuration, and its functional operation will be explained next. The principle of the image forming method using light-transmitting particles to which this example is applied is to first electrostatically adhere a layer of light-transmitting particles (hereinafter referred to as toner) to the surface of a uniformly charged photoreceptor. . After that, image exposure is performed on the photoreceptor through the toner,
Charges under the toner are partially removed according to the image to form a latent image.

Further, depending on the formed latent image, only the toner with weak electrostatic adhesion from which the charge directly below has been removed is selectively removed by the developing device. The process is completed by transferring the toner image corresponding to the exposed image remaining on the photoreceptor to the image receiving paper, developing color, and fixing it.

This example is applied to this developing process.

The toner is adhered in a layer and the photoreceptor part that has been exposed to image light is
As the photosensitive drum 6 rotates, the toner is subjected to electrostatic attraction due to the electric field between the developing rollers. At this time, only the toner whose electrostatic adhesion to the photoreceptor is weakened because the charge immediately below it has been removed during the Jg light is selectively flown by the electric field and adhered to the surface of the developing roller 1o.

The strength of the electric field generated at this time is determined by the amount of charge on the surface of the developing roller 10, the amount of charge remaining on the photoreceptor, and the distance therebetween. In other words, the higher the distance, the greater the electric field strength, but if it exceeds a certain height that corresponds to the distance, discharge will start and the electric field strength will be disturbed, making the developing power unstable or weak. It happens. The smaller the distance, the greater the electric field strength at the discharge start limit corresponding to this distance. Therefore, the electric field strength in the gap can be increased by making the gap 30 as small as possible and making the surface potential of the developing roller 10 as high as possible below the discharge starting potential determined by the distance. Therefore, this gap amount has a very large effect on the quality of the final image. In this embodiment, the gap 30 is delicately adjusted as follows.

In FIG. 2, when the lock nut 16a is loosened and the bearing 14a is rotated, the position of the bearing 14a is moved back and forth with respect to the female screw of the support plate by the screw, and the spring 13 is accordingly moved.
The guide roller 11a biased by the force a also moves back and forth in the axial direction. Since the photoreceptor drum is guided in a par-shape, the amount of gigang 30 produced varies depending on the axial position of the guide roller.

Furthermore, the amount of rotation of the bearing 16a is greatly reduced by the screw lead and the taper travel, resulting in a change in the amount of gear sawing 30. The same applies to the guide roller 11b on the opposite side, and by adjusting each independently, the inclination of the gear knob amount 30 with respect to the axial direction can also be adjusted.

On the other hand, the l·ner adhering to the developing roller 0 accumulates at the end of the blade 28 as the developing roller 0 rotates. Further, the toner remaining on the photoreceptor and forming the image is transferred to the image receiving paper in other areas (not shown). In this example, as described above, the amount of gas inflow between the photoreceptor and the developing roller, which has a significant effect on image quality, is finely adjusted.

Next, another embodiment will be described based on FIG. 4.

The guide portions 32a and 32b at both ends of the photosensitive drum 31 are tapered in the same direction as shown in the figure.
I'm in the middle of the day, and I'm in the middle of the day. ++h old se! guide roller 34
Correspondingly, a and 34b also have tapers in the same direction. A supporting plate 36 that rotatably supports the developing roller 33 through bearings 35a and 36b has one end connected to a pin 38 implanted in a side plate 37b, and the other end connected to a pin 40 screwed to a NAND capital 39 of the side plate 37a. Each is supported by a shaft. The position of the pin 38 when viewed from the side is the same as 25a in the real sister example in FIG. The position of the support plate 36 in the axial direction of the developing roller varies depending on the position of the pin 40 because one end is biased by a spring 41 . Therefore, as before, by loosening the lock nut 42 and rotating the pin 40, the developing roller 33 and the guide roller 34a including the support plate 3e are removed.

The entire 34b can be moved back and forth in the axial direction.

A driving gear 43 is attached to the end of the developing roller 33, and engages with an intermediate gear (not shown) in the same arrangement as the embodiment shown in FIG. It is connected to the gear 44 of the photoreceptor drum 31.

46a, 45b and 46a, 46b are stopper stems, which respectively regulate the relative positions of the guide roller 3'--41* roller 33, the developing roller 33, and the support plate 36 in the axial direction.

The other parts of this embodiment have the same structure as in FIGS. 2 and 3. As described above, in this embodiment, the pin 4 is tapered in the same direction and by the same amount on both sides.
By rotating 0, the amount of gear sawing 47 can be adjusted while maintaining parallelism between the photosensitive drum 31 and the developing roller 33.

As described above, the present invention makes it possible to finely adjust the amount of gigang between the photosensitive drum and the developing roller, which has a significant effect on the quality of the final image. In the embodiment, an example was given in which the present invention was applied to an image forming method using light-transmitting grains/hills, but the same applies to an electrophotographic developing device using a normal Carlson process. The present invention can also be effectively utilized in a similar manner when it is necessary to maintain a minute gap between the recording medium and the recording head, such as trench electrostatic recording.

Effects of the Invention The developing device according to the present invention has the following effects due to the configuration and functions described above.

(1) It is possible to adjust the delicate circumference of the gear between the photoreceptor and the developing roller, which has a serious effect on the image quality of the final 4J image.

(2) Even if the accuracy of each constituent part varies, it can be adjusted after final assembly without replacing the parts.

(3) Gear deviation between the photoreceptor and the developing roller can be adjusted in response to variations in the developing performance and photoreceptor performance of each device.

(4) (y!1. Since it is possible to make strange adjustments, it is possible to set the gap between the photoreceptor and the developing roller as a design standard to a small value, and there is a margin for developing power.A developing method that requires a particularly strong electric field In this case, since the gap amount can be set to a small value, a high discharge starting electric field and a strong developing power can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a conventional developing device with essential parts cut away, FIG. 2 is a diagram of a developing device according to one embodiment of the present invention, and FIG. 4 is a diagram of a developing device applied to another embodiment. FIG. 3 is a plan view with main parts cut away. 6, 31--Photosensitive drum, 7a, 7b, 32
a. 32b...Guide portion, 10.33...Developing roller, 11a, 11b, 34a, 34b--Guide roller, 14a, 14b...Bearing, 27...
・Charger, 28...Blade, 40...Pin. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 3
Figure 4

Claims (3)

[Claims] (1) A photoreceptor drum and a developing roller facing it,
The developing roller includes a guide roller coaxially and rotatably supported by the developing roller, and urging means for urging the developing roller so that the outer periphery of the guide roller comes into contact with a part of the outer periphery of the photoreceptor drum. . A developing device, wherein at least one of the contact portions of the photosensitive drum and the guide roller is tapered. (2) The developing device according to claim 1, wherein the position of the guide roller can be moved and adjusted in the axial direction of the developing roller. (3) The developing device according to claim 1 or 2, wherein the developing roller and the guide roller can be integrally moved and adjusted in the axial direction with respect to the photosensitive drum.