JPH01304473A - charging device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The invention relates to a contact type charging device used, for example, in an electrophotographic device for forming an image, and more specifically, to a charging member in a charging device, a method for charging a charged object, The present invention relates to a charging device that prevents deterioration.

Conventionally, in contact-type charging devices used in electrophotographic image forming apparatuses that form images using an electrophotographic process, a voltage is generally applied to a conductive charging member such as a charging roller. It is common to charge the photoreceptor drum by applying a charge and bringing this charging member into contact with a charged object such as a photoreceptor drum, and as the charging member, in addition to a roller shape such as a charging roller, Brush and blade shapes are used. Charging by this method has been conventionally carried out by, for example, rotating a conductive roller, which is a charging member, in contact with a photoreceptor drum, which is an object to be charged, and applying a voltage of IKV to 2KV to the conductive roller. , the photoreceptor drum was charged to 500V-IKV.

However, the conventional charging method described above may have the following drawbacks. That is, in general,
As mentioned above, in a contact type charging device, the voltage applied to a charging member such as a charging roller is about 1 to 2 KV, which is lower than that of a conventional corona charger, and there is no wasteful electricity such as shielding current. Since there is no current, the ozone acid generated during the charging process is minute, but when the contact charging described above is actually performed using a charging roller, as shown in Figure 5, the charging The generation of weak ozone has been observed near the contact area between the roller and the photoreceptor drum, and this ozone generation can cause charging problems such as blurred images, deterioration of the surface of the photoreceptor drum or characteristics of the charging member, and shortening of the life of the charging member. This causes various problems with the equipment.

This method of observing ozone generation will be further explained with reference to FIGS. 2 and 5.

As shown in FIG. 5, a charging roller 2 as a charging member is disposed so as to rotate in pressure contact with a photoreceptor drum l as a charged object of a charging device. , a power supply section 3 for applying a predetermined voltage to the charging roller 2 is connected. Further, an ozone measuring device 4 is disposed and sunk near the contact portion between the photosensitive drum 1 and the charging roller 2 so as to be able to measure ozone generated during the charging process of the charging device.

With this configuration, when the charging roller 2 was brought into contact with the photoreceptor tram 1 and contact charging was performed on the photoreceptor drum 1, A near the contact portion between the photoreceptor drum 1 and the charging roller 2 was detected.
, A flash of light due to the discharge was seen in the part B, and ozone was observed by the ozone measuring device 4 near the contact area. The measurement results are shown in Figure 2, where the vertical axis represents the ozone concentration and the horizontal axis represents the applied voltage, and as shown by the graph shown by the solid line, ozone is generated due to the discharge. I understand that.

As shown in FIG. 2, the contact mt as described above
l! The degree of ozone generation caused by . Although the amount of ozone generated is extremely low and the absolute amount of ozone generated is small, the generation of ozone near the contact area between the photoreceptor drum and the charging roller causes image blurring and photoreceptor drum damage as described above. Problems related to the charging device may occur, such as deterioration of the surface or characteristics of the charging member and shortening of its life.

That is, the influence of the generation of ozone significantly deteriorates the photosensitivity of the photoreceptor drum 1, so that, for example, it may not be possible to obtain a desired potential necessary for image formation.

In particular, the contact type i! In the device, W
After finishing the charging process and stopping the photoreceptor drum l, when the charging device is operated again to perform the next printing operation, near the contact area between the charging roller 2 and the photoreceptor drum 1 mentioned above, When the charging roller 2 is stopped, blurring of the image may occur in the area where the charging roller 2 is stopped, which appears to be caused by the influence of ozone.

This is because the corona charger is located apart from the photoreceptor drum, whereas in the contact type charging device, due to its structure,
Because the charging member is in direct contact with the photoreceptor drum,
It is thought that ventilation is unlikely to occur near the photoreceptor drum near the contact area between the charging member and the photoreceptor drum, and therefore there is a region where the concentration of ozone generated near this contact area is extremely high. As a result, as mentioned above, it is thought that image blurring, etc., appears to be caused by the influence of ozone.

Therefore, an object of the present invention is to provide a charging device that performs charging by bringing a charging member to which a predetermined voltage is applied from the outside into contact with an object to be charged, such as a photoreceptor drum. This removes ozone generated near the contact area between the charging member and the charged member, and prevents the accumulation of ozone. Another object of the present invention is to provide a charging device that eliminates the adverse effects of ozone on a photoreceptor drum.

The above objects are achieved by the charging device according to the present invention. That is, in summary, the present invention provides a contact that is formed by bringing a charging member to which a voltage is applied to a charged object into contact with the charged object in a charging device, and a contact that is formed by the contact between the charging member and the charged object. This charging device is characterized in that a ventilation path means is provided along the longitudinal direction near the portion, and air is caused to flow through the ventilation path means.

That is, according to one aspect of the present invention, in a contact type charging device that performs charging by bringing a charging member to which a predetermined voltage is applied from the outside into contact with a charged object, the contact formed by contact between the charging member and the charged object. By providing a ventilation passage means along the longitudinal direction near the contact part, air is allowed to flow through the ventilation passage means, thereby preventing the accumulation of ozone generated by discharge in the vicinity of the contact part.

By doing this, it is possible to prevent ozone from accumulating in the vicinity of the contact area between the charging member and the charged object, and as a result, the photoconductor drum as the charged object can be prevented from accumulating in the vicinity of the contact area between the charging member and the charged object. deterioration of the surface or characteristics of the charged member and shortening of its life.

This can prevent image blurring and the like.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be described below based on embodiments thereof with reference to the attached drawings.

Referring to FIGS. 1A and 1S, the contact type camera according to the present invention used in electrophotographic image forming apparatuses, etc. ? ? A schematic configuration diagram of an electrical equipment-embodiment is shown, and this contact type charging device is equipped with a photoreceptor drum l as a charged member, and this photoreceptor drum l is moved in a predetermined direction in the direction of the arrow in FIG. 1a. The drum rotates at a speed of They are arranged to rotate in contact. The charging roller 2 includes a power supply section 3 for applying a predetermined voltage to the charging roller 2.
is connected.

Here, in this embodiment, the photoreceptor drum 1 has an outer diameter of about 3
The charging roller 2 has a volume resistivity of 1 by dispersing carbon around a metal core with an outer diameter of about 6 mm.
The charging roller is coated with a rubber layer having a resistance of 0 Ωcm, and the final outer diameter of the charging roller is approximately L2 mm. As described above, when the charging roller 2 is arranged to rotate in contact with the photoreceptor drum L, it is pressed into contact with the photoreceptor drum L so that the nip width is approximately 1 mm, and As the drum l rotates, it rotates in the direction of the arrow in FIG. 1a.

The photosensitive drum 1 and the charging roller 2 described above are each attached at both ends to a side plate 8.8a disposed at a suitable position in the main body of the electrophotographic image forming apparatus. The method of attaching the charging roller 2 to the side plate 8.8a can be done by a conventionally used and known technique, so it is not shown in the drawings and its explanation will be omitted.

This predetermined position of the side plate 8.8a is a position corresponding to the ventilation passage 5b near the contact portion formed in the longitudinal direction when the photoreceptor drum 1 and the charging roller 2 are brought into pressure contact, in other words. Then, ventilation holes 5.5a are bored at positions corresponding to both longitudinal ends of the contact portion formed in the longitudinal direction, and air can enter and exit through these holes 5.5a. The surface is flattened to allow ventilation. The ventilation hole 5.5a and the ventilation passage 5b constitute a ventilation passage means.

A ventilation fan 6 for sending out or sucking air for ventilation is disposed at a suitable position in the image forming apparatus corresponding to the ventilation hole 5.5a. It is set up.

With this configuration, in the charging step of the image forming process, ozone generated by discharge near the contact portion between the photoreceptor drum 1 and the charging roller 2 can be removed to the outside of the side plate.

That is, the charging roller 2 is brought into contact with the photoreceptor drum 1, contact charging is performed on the photoreceptor drum 1, and ozone is generated due to discharge in the areas A and H near the contact area between the photoreceptor drum 1 and the charging roller 2. Even if this happens, air is sent out or sucked into the ventilation hole 5.5a by driving the ventilation fan 6, and air is sucked into the ventilation hole 5.5a in the longitudinal direction near the contact area between the photoreceptor drum 1 and the charging roller 2 (photoreceptor Drum l and charging roller 2
This generates ventilation in the ventilation path 5b formed as shown by the arrow in FIG. The air can be removed to the outside along the ventilation path 5b without being retained in the vicinity of the contact area.

The removal of ozone from the vicinity of the contact area between the photoreceptor drum 1 and the charging roller 2 in the above embodiment was performed in the same manner as described above.
The results of observation using an ozone measuring device 4 placed near the contact portion are shown in FIG.

As mentioned above, the solid line graph in FIG. 2 is based on the conventional example, and the dotted line graph is based on the present invention. As shown in the graph of FIG. 2, in both the conventional example and the one according to the present invention, the applied voltage is about 500
The discharge starts at V or higher, and the amount of ozone generated increases linearly thereafter.1 The ozone concentration of the device according to the present invention is lower than that of the conventional example, as shown by the dotted line graph in Figure 2. It can be seen that the value is much lower than that of .

The ozone concentration generated by the discharge is the same in both cases, the one according to the present invention and the one according to the conventional example, so the fact that the ozone concentration is low in the above embodiment of the present invention means that the ventilation passage 5b is This means that the ozone generated at the contact portion of the photosensitive drum 1 and the charging roller 2 in the longitudinal direction is removed by the effect of generating ventilation through the ventilation holes 5.5a.

Furthermore, in the above embodiment, the concentration of ozone generated by discharge near the contact portion of the photoreceptor drum 1 with the charging roller 2 is reduced to 0. Figure 3 shows the measurement of the change in residual ozone concentration as lppm over time after the end of discharge.The solid line graph in Figure 3 is based on the conventional example, and the one-dot line graph is This is according to the present invention. As is clear from FIG. 3, the ozone generated after the end of discharge remains in the vicinity of the photoreceptor drum in the case of the present invention shown by the dotted line, compared to the conventional example shown by the solid line. It will be understood that the residual ozone concentration decreases in a very short time after the discharge ends.

This is because the formation of the ventilation passages and ventilation holes described above generates ventilation through the ventilation holes 5.5a. This means that the generated ozone is removed extremely effectively and in a short time by ventilation, and this prevents ozone from remaining near the contact area between the photoreceptor drum 1 and the charging roller 2. It is possible.

As a result, it is effective to prevent blurring of images caused by ozone adhering to the surface of the photoreceptor drum.

The above-mentioned phenomenon of blurring of images on the photoreceptor drum is particularly noticeable in high temperature and high humidity environments.

In such a high-temperature, high-humidity environment, we conducted a durability test using the apparatus of the above embodiment in which ventilation channels and ventilation holes were formed to generate ventilation in the direction of the photoreceptor drum glue. No image blurring due to ozone occurred in the area where the image was stopped. Furthermore, as an acceleration test, the photoreceptor drum was stopped 17 in a high temperature and high humidity environment, 2000 V DC was applied to the charging roller 2 for 1 hour, and a printing operation was performed. No image blur was observed.

Next, another embodiment according to the present invention will be described with reference to FIG. 4. Referring to FIG. 4, a schematic configuration explanatory diagram of another embodiment of the contact type charging device according to the present invention is shown. Since this embodiment is almost the same as the above-mentioned embodiment shown in FIG. 1, the same members as those in the above-mentioned embodiment shown in FIG.

This embodiment is different from the above-described embodiment shown in FIG. is in pressure contact in the forward direction with a predetermined pressure.

Also in this embodiment, the charging blade 7 is attached to the photoreceptor drum 1.
When contact charging is performed on the photoreceptor drum l,
In the part A near the contact area between the photosensitive drum 1 and the charging blade 7, ozone is generated due to discharge as in the case of using the charging roller 2 of the embodiment described in 1i7j, but the ventilation fan 6 is driven. Therefore, in the case of this embodiment as well, as in the above-mentioned embodiments, it is formed along the longitudinal direction (the axial direction of the photoconductor drum 1 and the charging blade 7) near the contact portion between the photoconductor drum 1 and the charging blade 7. Ventilation can be generated in the ventilation passage 5b through the ventilation hole 5.5a, and by this ventilation, ozone generated at the contact portion of the photoreceptor drum 1 and the charging blade 7 in the longitudinal direction is extremely removed. It becomes possible to remove it to the outside effectively and in a short time. This makes it possible to prevent ozone from remaining in the vicinity of the contact portion between the photoreceptor drum 1 and the charging blade 7.

As a result, problems such as deterioration of the characteristics of the photoreceptor drum or charging blade and image blur caused by residual ozone do not occur, and this embodiment can also achieve the same effects as the embodiment described in B.1.

In the embodiments described above, a charging roller or a charging blade is used as the charging member, but the present invention is not limited to this. By providing ventilation passage means in the longitudinal direction along the length, the same effect as described above can be obtained.

Note that the above-mentioned ventilation path formed near the contact 811'fL between the photoreceptor drum and the charging roller or charging blade;
That is, when the photoreceptor drum and the charging roller are brought into pressure contact, a tubular member is arranged in the above-mentioned ventilation passage near the contact portion formed in the longitudinal direction, that is, the axial direction, to cover this ventilation passage. It is also possible to form a tubular ventilation passage.

i random difference] As explained above, according to the charging device of the present invention,
A ventilation passage means is provided along the longitudinal direction near the contact area formed by the contact between the charging member and the charged object, and air is caused to flow through the ventilation passage means, so that the electric discharge is generated. This prevents ozone from accumulating near the contact area.

This has the effect of being able to prevent deterioration of the characteristics of the surface of the photoreceptor drum, which is the object to be charged, the charging member, etc., shorten the lifespan, and prevent image blurring during image formation.

[Brief explanation of the drawing]

FIG. 1a is a schematic perspective view of an embodiment of a contact type charging device according to the present invention. FIG. 1 is a schematic front view of FIG. 1a. FIG. 2 is a graph diagram showing the relationship between the applied voltage applied to the charging device and the ozone concentration generated thereby. FIG. 3 is a graph showing the change in residual ozone concentration with respect to the elapsed time after the end of discharge for ozone generation. FIG. 4 shows contact charging according to the present invention. It is a schematic cross-sectional explanatory view of another Example of C position. FIG. 5 is a schematic cross-sectional view of an example of a conventional contact-type charging device. 1: Photoreceptor drum 2: Charging roller 3: Power supply unit 4 Niosin measuring device 5.5a + ventilation hole 5b: A air path 7/charging blade 8.8a: Side plate 1 and 2 (p: mJo2F Point 0 DC applied voltage (V) 0 10 20 30, .0 Elapsed time after completion of discharge [seconds]

Claims (1)

[Claims] 1) In a contact-type charging device that performs charging by bringing a charging member to which a voltage is applied into contact with an object to be charged, a charging member that is applied with a voltage is charged along the longitudinal direction near a contact portion formed by contact between the charging member and the object to be charged. 1. A charging device characterized in that a ventilation path means is provided, and air is caused to flow through the ventilation path means.