JPH02168286A - Picture forming 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] <Industrial Application Field> The present invention provides an electrophotographic device 5, an electrostatic recording device, etc., with a collecting member for collecting developer scattered from an image carrier, and the back lη of the recording material. The present invention relates to an image forming apparatus that does not cause problems.

<Prior Art> Conventionally, in an image forming apparatus such as an electrophotographic apparatus, an image carrier such as a drum-shaped photoreceptor whose surface is uniformly charged by a corona discharger is exposed to light to form an electrostatic layer image. A developing device applies a charged developer (hereinafter referred to as toner) to the latent image to form a visible image, and the cough image is transferred and recorded onto a recording material to form an image.

When performing transfer recording on the above-mentioned recording material, the recording material is guided to the surface of the image carrier by flat recording material guide members (hereinafter referred to as guide members) provided vertically facing each other, and the toner is transferred from the back side of the recording material. Transfer chargers that provide corona discharge with opposite polarity are widely used.

A metal member is used for the guide member in order to maintain its rigidity, and is constructed to maintain an arbitrary potential as shown in FIGS. 6 and 7.

This is because if the guide member 50 is grounded, there is a risk that the transfer corona current will escape through the guide member 50 through the recording material at high temperatures, causing a transfer failure.

On the other hand, when the guide member 50 is in a floating state, no transfer failure occurs, but the transfer corona current flowing from the transfer charger 51 charges the guide member 50 to a high potential, and the floating toner and the toner on the image carrier 52 are There was a risk that the guide member 50 would be attracted and the recording material would be stained.

Therefore, by grounding the guide member 50 via the constant voltage element 53 and always maintaining a constant potential, it is possible to prevent the transfer corona Ti flow from becoming high enough to cause stains or transfer defects. It can be prevented.

<Problems to be Solved by the Invention> However, with the above-mentioned conventional technology, good transfer recording is possible under normal usage conditions or usage environments, but for example, when the recording material is smaller than the image width of the image carrier 52, the image A toner image that is not transferred to the recording material is generated on the carrier 52, and if the recording operation continues, the toner may be scattered and floating toner may increase in the vicinity of the transfer charger 51.

In this case, since the guide member 50 is kept at a constant potential, toner does not easily adhere to it, but as the amount of floating toner increases, the guide member 50 gradually slips away.

Therefore, when guiding the recording material to the image carrier 52, the guide member 5
0 toner stains adhere to the back surface of the recording material and appear as back stains.

Further, the guide member 50 may be set apart from the image carrier 52 (4J).
In this case, stains due to adhesion of floating toner are reduced, but the adhesion of the recording material to the image bearing member 52 is reduced, and the transferability of the toner image is also reduced, which may result in transfer failure.

Furthermore, depending on the size of the recording material, there is a method of discharging the toner image formed on the image carrier 52 that is not transferred to the recording material by irradiating light with a lamp, etc., but this method is not possible if the device is small. There is no space to install the above-mentioned lamps, etc., and the cost tends to be high.

The present invention solves the problems of the prior art described above, and by providing a collection member between the guide member and the transfer means and displacing the collection member with respect to the image carrier and the transfer means, the above-mentioned An object of the present invention is to provide an image forming apparatus that can recover toner scattered from an image carrier and maintain image quality.

<Means for Solving the Problems> The means for solving the problems of the prior art described above and applied to the embodiments described below are electrostatic latent image forming means for forming an electrostatic latent image on an image carrier. a developing means for attaching charged toner to the electrostatic latent image to form a visible image; a guide member for guiding a recording material to the surface of the image carrier; and transferring the visible image to the green forest. a collection member located between the guide member and the transfer means for collecting toner that has flown from the image carrier; and a collection member that connects the collection member to the image carrier. The present invention relates to an image forming apparatus having a position variable means that is displaced relative to the transfer means.

<Operation> According to the above means, there is a collection member located between the guide member and the transfer means for receiving toner scattered from the image carrier, and a collection member that is connected to the image carrier and the transfer means. Since the guide member, the transfer means, etc. are provided with a position variable means for displacing the guide member and the transfer means, it is possible to change the position of the collection member according to changes in environmental conditions and collect the toner scattered from the image carrier. There is no leakage and dirt on the back side of the recording material can also be prevented.

Furthermore, it is possible to obtain an optimal transfer corona current by preventing transfer defects due to insufficient transfer corona current, thereby improving transfer efficiency and maintaining image quality.

<Embodiment> An embodiment of an image forming apparatus to which the present invention is applied will be described below with reference to the drawings.

[First Embodiment] FIG. 1 is an explanatory diagram showing a schematic configuration of an image forming apparatus to which the present invention is applied, and FIG. 2 is an explanatory diagram of the main parts thereof.

1 is a photosensitive drum serving as an image carrier, and 2 is an electrostatic latent image forming device. This electrostatic latent image forming device 2 uniformly charges the surface of the photosensitive drum 1 in advance using a primary charger, which is a corona discharge TL device, and exposes the photosensitive drum 1 to light reflected from an original or the like irradiated by an exposure lamp. Forms an electrostatic latent image on the surface.

Reference numeral 3 denotes a developing device for attaching charged toner to the electrostatic latent image formed on the surface of the photosensitive drum 1 to form and visualize a toner image.

4 is a pair of registration rollers, including a registration upper roller;
43 and a registration lower roller 4b, the recording material 6 is synchronized with the leading edge of the toner image formed on the photosensitive drum 1.
It is used to transport.

Reference numeral 5 denotes a guide member for guiding the recording material 6 conveyed to the photosensitive drum l by the pair of registration rollers 4, and is composed of an upper guide 5a and a lower guide 5b.
is grounded via a constant voltage element 7 such as a Zener diode or a varistor to maintain a constant potential.

6 is a recording material such as UA paper or a plastic sheet,
The photosensitive drum 1 is guided by the guide member 5 from the pair of registration rollers 4 and conveyed to the photosensitive drum 1 .

8 is a transfer charger which is a corona discharger for transferring the toner image formed on the photosensitive drum 1 onto the recording material 6;
9 removes the electric charge on the back surface of the recording material 6, and
from the photosensitive drum? ]1 This is a static elimination needle for separating.

Reference numeral 10 denotes a conveying device for conveying the recording material 6 onto which the toner image has been transferred m to a fixing device (not shown).

After the photosensitive drum 1 transfers the toner image onto the recording material 6, the toner remaining on the surface of the drum 1 is removed by a cleaning device 11, and the charged layer thickness is erased and initialized by a static eliminator (not shown) or the like. Image formation is performed by repeating the above process.

A collection member 12 is provided between the guide member 5 and the transfer charger 8 for collecting toner floating and scattered near the transfer charger 8.

This collection member 12 is freely rotated in the directions of arrows a and b in the figure by a variable position device 14 driven by a drive power source 13 under various conditions and placed at an appropriate position, thereby efficiently collecting scattered toner. It can be done.

Further, the collection member 12 is grounded and kept at a lower potential than the guide member 5.

Here, the cause of toner floating and scattering near the transfer charger 8 will be explained.

According to an experiment, the image forming operation is continued under the condition that the toner image width and toner image area on the photosensitive drum l are larger than the width and transfer area of the recording material 6.

In this case, when the transfer charger 8 was inactive, the guide member 5, including the area where the recording material 6 passed through, was not stained by toner at all. On the other hand, when the image forming operation was continued by operating the transfer charger 8, the guide member 5 was stained with toner.

From the above results, it was found that the floating and scattered toner was caused by the corona discharge of the transfer belt I device B.

Next, a process in which the scattered toner T is collected by the collection member 12 will be described with reference to the second example.

When the transfer corona current flowing into the recovery member 12 during the corona discharge of the transfer charger 8 is measured, it is 10 to 30 μA, and on the other hand, when the transfer corona current flowing into the guide member 5 is measured, it is 10. IjA or less and corresponds to 172 to 1/3 of the transfer corona current flowing into the collection member 12. The transfer corona current flowing through the guide member 5 did not change much even without the recovery member 12.

The transfer corona current flowing into the recovery member 12 is higher than the transfer corona current flowing into the guide member 5 because the recovery member 12 is closer to the transfer charger 8, although the recovery member 12 has a lower potential than the guide member 5. ing.

Since a large amount of the transfer corona current W flowing out from the discharge wire 8a of the transfer charger 8 flows to the collection member 12, the corona wind due to the corona discharge and the transfer corona current W head in the direction of arrow C, and the floating and scattered toner T is transferred to the corona. It heads toward the collection member 12 guided by the wind.

That is, since the cause of floating and scattered toner T is not scattering due to rotation of the photosensitive drum 1 but scattering due to corona discharge, the scattered toner T rides on the corona wind and moves in the direction of arrow C before reaching the guide member 5. guided by the collection member 12
Almost all of the scattered toner T is recovered.

Therefore, the toner T does not adhere to the guide member 5, and image formation can be performed under appropriate conditions. Further, since the collection member 12 can reduce the adhesion of scattered toner T to the transfer charger 8, image unevenness can be prevented and image quality can be maintained.

Here, the change in the position of the collection member 12 by the variable position device 14 and the state of collection of the scattered toner T will be explained.

When the variable position device 14 is driven by the drive type a13 and the recovery member 12 is rotated in the direction of the arrow a in FIG. 1, the recovery member 12 approaches the transfer charger 8 from the tip of the lower guide 5b of the guide member 5. Because of this position, as explained in FIG. 2, a large amount of transfer corona current W flows into the collecting member 12, and accordingly, the scattered toner T is well collected.

However, although the recovery rate of the scattered toner T is good, since the amount of transfer corona current W flowing into the recovery member 12 is large, there are cases where a large amount of the transfer corona current W is required (for example, when using moisture-absorbing paper in a high temperature environment, If thick paper or the like is used), there is a risk of insufficient transfer corona current, resulting in a decrease in transfer efficiency and a decrease in image density.

Therefore, when a large amount of transfer corona current is required,
The variable position device 14 is driven to rotate the collection member 12 in the direction indicated by the arrow, and the collection member 12 is moved away from the transfer charger 8 to prevent the transfer corona current W from flowing into the collection member 12 excessively, thereby improving the transfer efficiency. can be maintained in good condition.

In this case, the recovery member 12 is rotated to a position where the tip of the lower guide 5b and the tip of the recovery member 12 substantially overlap in the direction of gravity, or to such an extent that the tip of the recovery member 12 slightly protrudes from the tip of the lower guide 5b. Then, the scattered toner T that contaminates the lower guide 5bjr is almost collected by the collection member 12, and the necessary transfer current can be secured for the transfer of the toner image, the transfer efficiency and image density are both good, and the back side of the recording material 6 is not stained. do not have.

Further, the drive power source 13 can be manually turned on and off depending on the peripheral filling (temperature, humidity, etc.) of the transfer charger 8 or the image forming apparatus.
F and drives the variable position device 14 to rotate the collecting member 12 in the direction of arrow a-b.

Further, switching is possible not only depending on the environmental conditions but also on the thickness, material, moisture absorption, etc. of the recording material 6. For example, when used at normal temperature and humidity, the collection member 12 is rotated in the direction of arrow a, and when used at high temperatures or when N paper, resin material, moisture absorbing paper, etc. is used as the recording material 6, the collection member 12 is rotated. Rotate in the direction of the arrow to use.

[Second Embodiment] Next, another embodiment of the recovery member 12 and its drive system in the first embodiment will be described with reference to FIG. 3.

For example, in a high-temperature environment, the flow of the transfer corona 11 is likely to be transmitted through the absorbed recording material 6 and generate an electric current, which may cause a transfer failure or an excessive charge removal current, which may cause the image to be transferred again using the photosensitive drum 1. There is a possibility that the concentration may be reduced.

In addition, in a low humidity environment, the recording material 6 becomes low in humidity and has a high resistance, so a transfer corona of 1 ftL% is sufficient for transfer with a smaller amount than usual.
There is an IS error in which the recording material 6 is peeled off due to uneven transfer and insufficient static elimination current.

Furthermore, the toner on the photosensitive drum l that is not transferred to the recording material 6 is likely to scatter, causing stains on the recording material 6 and the transfer charger 8.

In this embodiment, as shown in FIG. 3, the collecting member 15 is provided with meshing teeth on its back surface, and can be moved in the direction of the arrow d%e by meshing with the variable position gear 16. Further, the variable position gear 16 is driven by a drive power source 17, and the drive power source 17 is provided with a temperature discriminator 1B and a temperature/humidity detector 19 in this order.

Further, the recovery member 15 is connected to L via a variable voltage power source 20.
(temperature recording) connected to the temperature discriminator 18.

The temperature/humidity detector I9 detects the temperature around the transfer charger 8, and based on the detected temperature/humidity, the temperature/humidity determination 231B determines the optimum position of the recovery member 15 for the required amount of transfer corona current. A signal is transmitted to the drive power source 17. The drive power source 17 rotates the variable position gear 16 by a required amount to move the collecting member 15 in the direction of the arrow d%e in the figure.

Further, a signal is transmitted from the temperature/humidity discriminator 18 to the voltage variable power supply 20, and if the flow of transfer corona 7Il flowing into the collection member 15 is larger than necessary, the voltage of the collection member 15 is changed to the voltage of the transfer charger 8. It is configured to raise the polarity to the same as the corona discharge polarity.

- For example, when the temperature is 30°C or higher and the humidity is 60% or higher, the collecting member 15 is moved in the direction of arrow e in the figure according to the judgment of the temperature/humidity discriminator 18, and when the temperature is 30°C or higher and the humidity is 60% or higher,
% or less, the collecting member 15 is moved in the direction of the arrow d in the figure, and at temperatures and humidity other than the above, the optimum position is determined in the middle of the arrow d w e.

By configuring as described above, 7
It is possible to obtain high-density, high-quality images with no blur.

[Third Embodiment] Next, another embodiment of the recovery member 15 and its drive system in the second embodiment will be described with reference to FIG. 4.

FIG. 4 shows the temperature and humidity discriminator 18 of the collection member 15 and its drive system in the second embodiment. A recording material discriminator 21 is used instead of the temperature/humidity detector 19. A recording material size detector 22 is provided.

The registration roller pair 4 is detected by the recording material size detector 22.
detects the size of the recording material 6 conveyed to the guide member 5, and based on the detected size, the recording material size discriminator 21 sends a signal to the drive power source 17 while the recording material 6 is passing through the lower guide 5b, The variable position gear 16 is rotated by the required amount to move the collection member 15 in the direction of arrow e in the figure.

The recording material size discriminator 21 determines that the recording material 6 is
Immediately after J1M has passed through b, a signal is sent to the drive power source 17 to rotate the variable position gear 16 by the required amount to remove the collecting member 1.
5 in the direction of arrow d, transfer corona 7S, ? A large amount of N flows into the collection member 15 to efficiently collect the scattered toner T.

[Fourth Embodiment] Next, another example (2) of the static eliminating needle 9 in the second embodiment will be described with reference to FIG.

In the second embodiment, as shown in FIG. 3, a charge eliminating needle 9 is provided adjacent to the transfer charger 8 to remove the charge on the back side of the recording material 6 and separate the recording material 6 from the photosensitive drum l. However, in this embodiment, a separation static eliminator 23, which is a corona discharger, is provided in place of the static eliminator needle 9.

This separation static eliminator 23 applies an alternating electric field to the back surface of the recording material 6 by corona discharge, and peels off the recording material 6 electrostatically attracted to the photosensitive drum 1. In this case, the polarity of the corona discharge current in the transfer charger 8 and the separation static eliminator 23 is reverse-polarity, and they electrically interfere with each other, so that the separation static electricity removal performance tends to become unstable. If the moisture absorption of No. 6 differs, the discharge state and static elimination efficiency will change.

In this embodiment, the temperature and humidity I moxibustion detector 19 detects the temperature and humidity around the device, and the temperature and humidity discriminator 18 transmits a signal to the drive power source 17 in accordance with the detected temperature and humidity, and the variable position gear 16 is rotated to move the collection member 15 in the direction of arrow d-e in the figure.

For example, in a high temperature environment (60% or higher), in order to prevent the transfer corona current from flowing into the collection member 15, the collection member 15 is moved in the direction of arrow e, and the transfer electric field on the back surface of the recording material 6 is reduced to the normal level. By making the temperature the same as in the case of temperature and stabilizing the separation charge removal efficiency, it is possible to improve the transfer efficiency and prevent transfer defects.

In addition, in a low-humidity environment (1 degree of difficulty 30% or less), the collection member 1
5 in the direction of arrow d, injection of excessive corona to the back surface of the recording material 6 and excessive transfer electric field can be prevented, thereby preventing insufficient separation and charge removal.

Furthermore, by setting the potential of the recovery member 15 to a high potential of the same polarity as that of the transfer charger 8 in a high temperature environment, and to a low potential or a potential of the opposite polarity to that of the transfer charger 8 in a low humidity environment. It is possible to further enhance the above effects.

With the above configuration, it is possible to maintain high-quality images with stable transfer efficiency under various environmental conditions, improve the separation performance between the photosensitive drum 1 and the recording material 6, and increase the recovery rate of scattered toner T. It is possible to prevent contamination of No. 6 and prevent tη leakage inside the device.

<Effects of the Invention> As described above, the present invention includes a collection member located between a guide member and a transfer means for receiving toner scattered from an image carrier, and a collection member that is connected to the image carrier and the transfer member. Since the position variable means for displacing with respect to the means is provided, the position of the collecting member can be changed in accordance with changes in environmental conditions to collect the toner scattered from the image carrier, and the guide member and the transfer member can be moved. It does not stain the means, etc., and can also prevent the back surface of the recording material from getting dirty.

Furthermore, it is possible to obtain an optimal transfer corona current by preventing transfer defects due to insufficient transfer corona current, thereby improving transfer efficiency and maintaining image quality.

FIG. 1 is an explanatory diagram showing a schematic configuration of an image forming apparatus that can apply the present invention, FIG. 2 is an explanatory diagram of its main parts, and FIGS.
The figure is an explanatory diagram of the other side, and FIGS. 6 and 7 are explanatory diagrams of a conventional example.

1 is a photosensitive drum, 2 is an electrostatic latent image forming device, 3 is a developing device,
4 is a registration roller pair, 5 is a guide member, 6 is a recording material,
7 is a constant voltage element, 8 is a transfer charger, 8a is a discharge wire, 9 is a static elimination needle, IO is a transport device, 11 is a cleaning device, 12.15 is a collection member, 1317 is a drive power source, 14
16 is a variable position device, 16 is a variable position gear, 18 is a temperature/humidity discriminator, 19 is a temperature/humidity detector, 20 is a variable voltage power source, 21
2 is a recording material size discriminator, 22 is a recording material size detector, 2
3 is a separation static eliminator.

Claims (3)

[Claims] (1) An electrostatic latent image forming means for forming an electrostatic latent image on an image carrier, a developing means for applying a charged developer to the electrostatic latent image to form a visible image, and recording. a recording material guide member for guiding a material to the surface of the image carrier; a transfer means for transferring the visible image onto the recording material; located between the recording material guide member and the transfer means; An image forming apparatus comprising: a collection member for collecting developer scattered from the image carrier; and a position variable means for displacing the collection member with respect to the image carrier and the transfer means. (2) The image forming apparatus according to claim (1), further comprising a potential variable means connected to the collecting member and a means for detecting temperature and humidity around the transfer means. (3) Claim (1) wherein a potential variable means connected to the collecting member is provided, and a means for detecting the size of the recording material is provided.
1) The image forming apparatus described above.