JPH11212340A - Image forming device - Google Patents

Abstract

(57) [Summary] [Problem] To eliminate discharge unevenness, to achieve density unevenness, transfer failure,
While preventing poor separation, it also extends the life of the cleaning member and the discharge wire. SOLUTION: The attachment / detachment detection switch detects the attachment / detachment of a toner supply cartridge for supplying toner to a developing device to / from the image forming apparatus main body, and the number of replacements is detected by a replacement number counter. Control means 3
Reference numeral 6 appropriately sets a cleaning time interval for cleaning the discharge wire of the primary charger in accordance with the number of replacements. The discharge wire is connected to the toner supply amount, that is, the cartridge 31.
Of the cleaning members and discharge wires due to cleaning more than necessary, as well as to prevent discharge unevenness. Can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, such as a copying machine or a laser beam printer, provided with a cleaning member for cleaning a charging member such as a primary charging device, a transfer charging device, and a separation charging device.

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine or a laser beam printer, a corona charging device is often used as a charging member for performing primary charging on an image carrier, transfer charging to a transfer material, and separation charging. The corona charging device uses an electric charge generated by a corona discharge phenomenon generated by a strong electric field generated between a discharge wire to which a high voltage is applied and a shield electrode arranged opposite to the discharge wire, and uses an image carrier, a transfer material. And the like to charge or remove electricity.

[0003] The strength of the corona discharge phenomenon is easily affected by the state of the surface of the discharge wire. That is, since the surface of the discharge wire is liable to adhere foreign matter due to electrostatic dust collection, the corona charging device may cause uneven discharge distribution (hereinafter referred to as “discharge unevenness”) when used repeatedly. Are known. This discharge unevenness appears as image density unevenness when it occurs during the uniform charging process on the image carrier surface, and poor transfer or poor separation when it occurs during the transfer charging to the transfer material and the separation charging process. , And in any case, the quality of the image is degraded.

Therefore, in order to eliminate the unevenness of discharge of the corona charging device, which is the cause of the density unevenness, transfer failure, separation failure, etc., a cleaning means for automatically cleaning the surface of the discharge wire is provided. It has been proposed to operate periodically at predetermined time intervals. For example, it is practical to count the number of image forming operations (the number of prints) and operate the cleaning unit once every 2,000 times or to operate using the pre-rotation of the image forming apparatus when the main switch is turned on. Has been

[0005]

However, the above-described conventional example has the following problems.

[0006] The main foreign matter which easily adheres to the surface of the discharge wire is toner. It has been experimentally confirmed that the amount of toner adhering to the discharge wire is substantially proportional to the amount of toner used for image formation. That is, depending on the density of the image information, a large variation occurs in how the surface of the discharge wire becomes dirty. For example, when a large number of images close to solid black are produced, the discharge wires become rapidly stained. Therefore, the discharge unevenness cannot be completely prevented only by cleaning at the conventional predetermined time intervals. However, there is a problem that separation failure occurs.

[0007] Density unevenness has the following problems. In recent years, many image forming apparatuses capable of outputting halftone density images have been put into practical use with high performance, and when outputting many images including halftone density, the surface of the image carrier before image exposure is required. High accuracy is required for the uniformity of uniform charging, but cleaning the discharge wire at a predetermined time interval alone cannot meet the high accuracy of uniformity. Is a problem that density unevenness occurs in the image.

In order to solve these problems, it is effective to increase the number of times of cleaning by uniformly shortening the time interval for cleaning the discharge wires in accordance with the most severe conditions.

However, if the time interval is shortened uniformly, the following two problems occur. First, in a conventional device used in an environment or situation that can withstand practical use even at a predetermined time interval, the life of the discharge wire itself as well as the cleaning member of the discharge wire itself is unnecessarily shortened. . Secondly, when the user uses the image forming apparatus, there is a problem that the user often waits for image formation for cleaning.

Therefore, the present invention eliminates discharge unevenness,
Provided is an image forming apparatus that prevents density unevenness, transfer failure, and separation failure, extends the life of a cleaning member and a discharge wire, and reduces a user's waiting time for cleaning the discharge wire. It is intended to do so.

[0011]

According to a first aspect of the present invention, there is provided an image forming apparatus, comprising: a primary charging device for charging a surface of an image carrier; and a primary charging device for charging the surface of the image carrier after charging. Cleaning means for cleaning a charging member of the primary charging device, and a toner supply amount from the developing device. And a control unit that adjusts a cleaning time interval of the charging member by the cleaning unit according to a toner supply amount detected by the toner supply amount detection unit. And

According to a second aspect of the present invention, there is provided an image forming apparatus for developing a toner image by attaching toner to an electrostatic latent image formed on the surface of an image carrier, and transferring the toner image on the image carrier. An image forming apparatus including a transfer charging device that transfers the toner onto a material; a cleaning unit that cleans a charging member of the transfer charging device; a toner supply amount detection unit that detects a supply amount of toner from the developing device; Control means for adjusting a cleaning time interval of the charging member by the cleaning means according to a toner supply amount detected by the toner supply amount detection means.

According to a third aspect of the present invention, there is provided an image forming apparatus, comprising: a developing device for attaching toner to an electrostatic latent image formed on the surface of an image carrier to develop the toner image as a toner image; And a separation charging device for separating the transferred transfer material from the surface of the image carrier,
Cleaning means for cleaning a charging member of the separation charging device; toner supply amount detection means for detecting a toner supply amount from the developing device; and a toner supply amount detected by the toner supply amount detection means. Control means for adjusting a cleaning time interval of the charging member by a cleaning means.

An image forming apparatus according to a fourth aspect of the present invention includes a counting unit for detecting the number of times an image has been formed, and the control unit controls the toner supply amount according to an output of the toner supply amount detecting unit and the counting unit. A cleaning time interval of the charging member by a cleaning unit is adjusted.

An image forming apparatus according to claim 5, further comprising a replenishing toner container for replenishing toner to the developing device, wherein the toner supply amount detecting means counts the number of replacements of the replenishing toner container to count toner. Detect supply amount,
It is characterized by the following.

7. The image forming apparatus according to claim 6, wherein the charging member has a discharge wire disposed opposite to the surface of the image carrier, and the cleaning means sandwiches the discharge wire in a longitudinal direction of the discharge wire. And a cleaning member that can be moved.

[Operation] The main operation based on the above configuration is as follows.

The cleaning member cleaning time interval can be appropriately set according to the contamination of the charging member which is substantially proportional to the toner supply amount.

[0019]

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

Embodiment 1 FIG. 1 shows an example of an image forming apparatus according to the present invention. FIG. 1 is a longitudinal sectional view showing a schematic configuration of a copying machine or a laser beam printer using a scorotron type charger as a charging device and a corotron type charger as a transfer device and a separation device.

The image forming apparatus shown in FIG. 1 includes a drum type electrophotographic photosensitive member (hereinafter referred to as "photosensitive drum") 10 as an image carrier. The photosensitive drum 10 has, for example, an organic optical semiconductor (OP) on a surface of a drum base made of aluminum.
C) or the like, and is configured to be rotated in a direction of an arrow R10 by a driving unit (not shown).

The surface of the photosensitive drum 10 is uniformly charged by a primary charging device having a primary charging member (charging member) 11 and a power supply (not shown) for applying a charging bias thereto. The primary charging member 11 includes a shield plate 20 having a U-shaped cross section with an opening directed toward the surface of the photosensitive drum 10, a discharge wire 21 disposed inside the shield plate 20, and a grid wire 24 disposed in the opening of the shield plate 20. And applies a predetermined charging bias to the discharge wire 21 and the grid wire 24 to uniformly charge the surface of the photosensitive drum 1 to a predetermined polarity and a predetermined potential.

The surface of the charged photosensitive drum 10 is subjected to image exposure 12 according to image information by an exposure means (not shown), and the charge of the light-irradiated portion is removed to form an electrostatic latent image. The electrostatic latent image is developed with the toner by the developing device 13 as a toner image.

The toner image on the photosensitive drum 10 is transferred onto a transfer material 19 by a transfer charging device having a transfer charging member (charging member) 15 and a power supply (not shown) for applying a transfer bias thereto. The transfer charging member 15 has a U-shaped shield 15 having an opening facing the photosensitive drum 10.
a and a discharge wire 15b disposed inside thereof, which is a corotron type charger which is sent in synchronization with the toner image on the surface of the photosensitive drum 10 and is brought into close contact with the surface of the photosensitive drum 10 by the transfer material guide member 14. Transfer material 1 such as torn paper
9, the toner image on the photosensitive drum 10 is electrostatically transferred.

On the downstream side of the transfer charging member 15 in the transfer direction of the transfer material 19, a separation charging member (charging member) 16 is provided.
And a power supply (not shown) for applying a separation bias thereto. Separation charging member 16
Is a corotron-type charger having a U-shaped shield 16a having an opening toward the photosensitive drum 10, and a discharge wire 16b disposed inside the shield 16a, like the transfer charging member 15. The separation charging member 16 separates the transfer material 19 from the surface of the photosensitive drum 10 by removing a part of the transfer charge on the back surface of the transfer material 19 after the transfer of the toner image.
After the toner image is fixed on the surface of the transfer material 19 after separation by a fixing device (not shown), the transfer material 19 is discharged outside the image forming apparatus main body. On the other hand, the photosensitive drum 10 after the transfer of the toner image
The toner remaining on the photosensitive drum 19 without being transferred to the transfer material 19 (transfer residual toner) is
, And is further discharged by the exposure 18 of the pre-exposure device, and supplied to the next image forming apparatus.

Next, the features of the present invention will be described in detail.

As shown in FIG. 1, the developing sleeve 13
The photosensitive drum 1 includes a developing sleeve 13a opposed to the surface of the photosensitive drum 1 with an appropriate gap therebetween, and a stirring / transporting member 13b disposed adjacent to the developing sleeve 13a. Further, a toner amount detection sensor (not shown) for detecting the amount of toner in the developing device 13 is attached inside.
An auxiliary toner tank 32 is mounted on the upper part of the developing device 13, and the same agitating / transporting member 3 as described above is provided inside the auxiliary toner tank 32.
2a and 32b are provided. Further, a toner supply cartridge (supply toner container) 31 containing toner 33 is mounted on the upper part. This cartridge 31 is detachable from the image forming apparatus main body.

An attachment / detachment detection switch 34 (see FIG. 2) is provided behind the toner supply cartridge 31. The attachment / detachment detection switch 34 can detect that the cartridge 31 has been replaced with a new one. It has become. The information detected by the attachment / detachment detection switch 34 can be transmitted to the cleaning member drive motor 37 of the primary charging member 11, the transfer charging member 15, and the separation charging member 16 via the replacement number counter 35 and the control means 36. I have. In the present embodiment, the toner supply amount detecting means is constituted by the attachment / detachment detection switch 34 and the replacement number counter 35.

FIG. 3 is an enlarged vertical sectional view of the primary charging member 11. The primary charging member 11 is formed long along the axial direction of the photosensitive drum 10. As described above, the primary charging member 11 has the shield plate 20, the discharge wires 21, and the grid wires 24 that are longer than the width of an image that can be output. Further, an automatic discharge wire cleaning device 50 is attached to the primary charging member 11. The discharge wire automatic cleaning device 50 includes a discharge wire cleaning member (cleaning member) 22 that sandwiches and cleans the discharge wire 21, a support member 23 that supports the discharge wire cleaning member 22, and a support member 23.
As shown in FIG. 4, a supporting member moving mechanism (not shown) for moving the supporting member in the direction of the arrow along the discharge wire 21 and a cleaning member driving motor 37 for driving the supporting member moving mechanism are provided. FIG. 4 is a perspective view showing the movement of the automatic discharge wire cleaning device 50 during cleaning of the discharge wire 21.
However, in FIG. 4, the vertical direction is reversed from that in FIG. As the above-described discharge wire cleaning member 22, a synthetic leather, a sponge-like elastic member in which an abrasive or the like is dispersed or applied, or the like can be used.

Next, the operation of the discharge wire automatic cleaning device 50 and the like will be described.

By forming an image on a large number of transfer materials 19, if the developing device 13, the auxiliary toner tank 32, and the toner supply cartridge 31 run out of toner,
A toner amount detection sensor (not shown) in the developing device 13 detects the absence of toner. When the toner amount detection sensor detects that there is no toner, a warning of "no toner" is displayed on a display unit (not shown) of the image forming apparatus main body. By the display, the user can use the cartridge 31 for toner supply.
Is exchanged for a new one. As a result, continuation of image formation is enabled. On the other hand, the attachment / detachment detection switch 34 detects the replacement of the cartridge 31 and transmits the detection information to the replacement counter 35 as shown in FIG. The exchange number counter 35 having obtained the information accumulates the number of exchanges until a predetermined number is reached, and transmits the information to the control means 36 when the predetermined number is reached. Thereafter, the control means 36 controls the cleaning member drive motor 3 at a timing at which no support is given to the image forming process.
7 is given an operation signal. Thereby, as shown in FIG. 4, the cleaning member support member 23 reciprocates in the direction of the arrow over the substantially entire length of the discharge wire 21 for a predetermined time via the cleaning member drive mechanism, and the cleaning member 22 slides the discharge wire 21. By rubbing, the discharge wire 21 is cleaned.

The relationship between the number of replacements of the toner supply cartridge 31 and the operation timing of the discharge wire cleaning member 22 can be substantially determined according to the toner capacity of the toner supply cartridge 31. In the present embodiment,
Assuming that the toner capacity of the cartridge 31 is 500 g (for a standard document [6%] of 1,000 sheets),
It is set so that cleaning is performed once for every two replacements of.

By operating the automatic discharge wire cleaning device 50 as described above, the time interval for automatic cleaning of the discharge wire 21 can be reduced by the number of replacements of the toner replenishing cartridge 31,
That is, since the time interval is set according to the toner consumption, the degree of contamination of the discharge wire 21 during cleaning can be managed to approximately the same level. Therefore, the discharge wire cleaning member 2
2 can be easily selected, and cleaning can be performed at an optimum timing, so that cleaning efficiency is improved and the discharge wire 21 is improved.
In addition, the life of the discharge wire cleaning member 22 can be extended. In addition, unevenness in discharge is eliminated, and unevenness in image density due to unevenness in discharge can be prevented.

Further, since unnecessary cleaning is not performed, the time for which the user waits for cleaning can be reduced.

In addition, as shown in FIG. 2, if the information of an image forming operation number counter (counting means) 38 for detecting the number of times an image has been formed is taken into the control means 36, the discharge wires 21 due to discharge can be obtained. Degradation can also be taken into account. That is, for example, the number of image forming operations is 0
The cleaning is performed once every two times for the toner supply cartridge 31 up to 1000 times, and once every time the toner supply cartridge 31 is replaced once until the discharge wire 21 is changed for 1000 times or more. The cleaning frequency can be changed according to the degree of deterioration of the discharge wire 21 and the discharge wire cleaning member 22. By doing so, the cleaning effect can be further enhanced. As described above, when the output from the image forming operation counter 38 is also taken into the control means 36, in addition to the attachment / detachment detection switch 34 and the replacement counter 35 described above, The toner supply amount detecting means including the counter 38 is constituted.

<Embodiment 2> Referring to FIGS. 1 and 5,
Embodiment 2 will be described.

A toner concentration detecting means 42 (see FIG. 5) is provided in the developing device 13 or the auxiliary toner tank 32. The toner presence / absence information is transmitted by the toner concentration detection unit 42 and transmitted to the control unit 36. The control unit 36 controls the operation of at least one of the agitation / conveyance members 13b, 32a, and 32b as the toner supply unit 41 based on the information to reduce the toner supply amount, that is, the toner 33 on the upstream side. The amount of the toner to be sent toward the developing sleeve 13a in the developing device 13 on the downstream side is controlled. On the other hand, the control means 36 integrates the information on the time during which the stirring / conveying member is operated by the supply time settlement counter (toner supply amount detecting means) 40 and sends it to the cleaning member drive motor 37 when a predetermined time is reached. Send an operation signal.

With the above-described configuration, the same effect as that of the first embodiment can be obtained, and further, the control of the cleaning time interval can be performed finely. That is, while the cleaning time interval is based on the replacement of the cartridge 31 in the first embodiment,
In the second embodiment, since it can be subdivided into toner supply time units, more appropriate control can be performed.

In the first and second embodiments, the cleaning timing by the automatic discharge wire cleaning device 50 is set between jobs or an operation signal during a job so as not to interfere with the image forming process. It is desirable to operate after waiting for the end of the job even if is input. Further, for example, when it is necessary to provide an image formation prohibition state depending on the toner presence / absence state of the toner supply unit 41, the automatic discharge wire cleaning device 50 may be operated using the time required to return from the state. Good. This is because a job cannot be accepted during cleaning.

In the above-described first and second embodiments, the example in which the discharge wire automatic cleaning device 50 is mounted on the primary charging member 11 as the charging device has been described, but instead or in addition thereto. And discharge wire automatic cleaning device 5
0 may be attached to the transfer charging member 15 or the separation charging member 16. Automatic discharge wire cleaning device 5 in this case
0 is the primary charging member 11 shown in FIGS.
It can be the same as the one attached to. The effect when the discharge wire automatic cleaning device 50 is mounted on the transfer charging member 15 is to eliminate uneven discharge and prevent poor transfer, and the effect when mounted on the separation charging member 16 is as follows. In addition, it is possible to eliminate discharge unevenness and prevent separation failure. Furthermore, in each case,
As in the case where the discharge wire 2 is attached to the primary charging member 11,
The time interval of the automatic cleaning 1 is a time interval corresponding to the number of replacements of the toner supply cartridge 31, that is, the toner consumption amount.
The degree of contamination (see FIG. 1) can be managed to approximately the same degree. Therefore, the material of the discharge wire cleaning member 22 can be easily selected, and cleaning can be performed at an optimum timing, so that the cleaning efficiency is improved and the discharge wires 15b, 16
b and the life of the discharge wire cleaning member 22 can be extended. Further, since unnecessary cleaning is not performed, the time for which the user waits for cleaning can be reduced.

In addition, as shown in FIG. 2, if the information of the image forming operation number counter 38 is also taken into the control means 36, the deterioration of the discharge wires 15b and 16b due to the discharge can be taken into consideration. That is, for example, when the number of image forming operations is 0 to 1000, cleaning is performed once for every two times of the cartridge 31 for toner replenishment.
For 1000 times or more, the discharge wires 15b and 16b are converted, and once the toner supply cartridge 31 is replaced once, cleaning is performed once.
The cleaning frequency can be changed depending on the degree of deterioration of the discharge wire cleaning member 22 and b, 16b. By doing so, the cleaning effect can be further enhanced.

In the above description, the primary charging member 11 is of the Scottron type, and the transfer charging member 15 and the separation charging member 1
Although the charger 6 has been described as a corotron type charger, the scorotron type or the corotron type can be arbitrarily set.

Further, the present invention is not limited to the primary charging member 11, the transfer charging member 15, and the separation charging member 16, but is applicable to any other charging device, for example, a pre-transfer charging device for adjusting electric charges before transferring a toner image. It is also possible.

[0044]

As described above, according to the present invention,
By operating the cleaning means in accordance with the toner supply amount, while eliminating discharge unevenness, preventing density unevenness, transfer failure, separation failure, and extending the life of the cleaning member and the discharge wire, The waiting time of the user due to the cleaning of the discharge wire can be reduced.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a schematic configuration of an image forming apparatus according to the present invention.

FIG. 2 is a block diagram illustrating an operation of a discharge wire cleaning unit according to the first embodiment.

FIG. 3 is an enlarged vertical sectional view showing a configuration of a primary charger and a discharge wire cleaning unit.

FIG. 4 is a perspective view showing the operation of the discharge wire cleaning means.

FIG. 5 is a block diagram showing an operation of a discharge wire cleaning unit according to the second embodiment.

[Explanation of symbols]

Reference Signs List 10 image carrier (photosensitive drum) 11 charging member (primary charging member) 13 developing device 15 charging member (transfer charging member) 15b, 16b, 21 discharge wire 16 charging member (separate charging member) 19 transfer material 22 cleaning member (discharge) Wire cleaning member 31 supply toner container (cartridge) 34 toner supply amount detection means (removal detection switch) 35 toner supply amount detection means (replacement number counter) 36 control means 38 counting means (image forming operation number counter) 40 toner supply Amount detection means (supply time integration counter) 50 Cleaning means (discharge wire automatic cleaning device)

Claims (6)

[Claims] A primary charging device for charging the surface of the image carrier; and a developing device for attaching toner to an electrostatic latent image formed on the surface of the image carrier after charging and developing the toner as a toner image. In the image forming apparatus, a cleaning unit that cleans a charging member of the primary charging device; a toner supply amount detection unit that detects a supply amount of toner from the developing device; and a toner supply amount that is detected by the toner supply amount detection unit Control means for adjusting a cleaning time interval of the charging member by the cleaning means in accordance with the image forming apparatus. 2. A developing device for attaching toner to an electrostatic latent image formed on the surface of an image carrier and developing the toner as a toner image.
An image forming apparatus comprising: a transfer charging device that transfers a toner image on the image carrier onto a transfer material; a cleaning unit that cleans a charging member of the transfer charging device; and a toner supply amount from the developing device. And a control unit that adjusts a time interval for cleaning the charging member by the cleaning unit according to the amount of toner supply detected by the toner supply amount detection unit. Image forming apparatus. 3. A developing device for attaching toner to an electrostatic latent image formed on the surface of an image carrier and developing the electrostatic latent image as a toner image.
An image forming apparatus comprising: a separation charging device that separates a transfer material after a toner image on the image carrier is transferred from the image carrier surface; and a cleaning unit that cleans a charging member of the separation charging device. A toner supply amount detecting unit for detecting a toner supply amount from the developing device; and a cleaning time interval of the charging member by the cleaning unit in accordance with the toner supply amount detected by the toner supply amount detection unit. An image forming apparatus comprising: a control unit. 4. A cleaning device, comprising: a counting unit configured to detect a number of times an image is formed, wherein the control unit cleans the charging member by the cleaning unit in accordance with an output of the toner supply amount detection unit and the counting unit. The image forming apparatus according to claim 1, wherein a time interval is adjusted. 5. A replenishing toner container for replenishing toner to the developing device, wherein the toner supply amount detecting means detects the toner supply amount by counting the number of replacements of the replenishment toner container. The image forming apparatus according to claim 1, 2, 3, or 4, wherein 6. The charging member has a discharge wire disposed opposite to the surface of the image carrier, and the cleaning means has a cleaning member that can move in the longitudinal direction of the discharge wire with the discharge wire interposed therebetween. The image forming apparatus according to claim 1, 2, 3, 4, or 5, wherein