JP2001117298A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device in which a photoreceptive body memory is suppressed by eliminating a destaticizing process and without limiting the size of a photoreceptor. SOLUTION: A photoreceptive drum 1 is provided so as to be rotatable in the direction of an arrow S1, and the surface is uniformly electrified by an electrifying means 2, and an electrostatic latent image is carried by an exposure means 3. The electrostatic latent image is carried to a developing area brought into contact with a developer carrier 41 which is rotating in the direction of the arrow S3 of a developing device 4, and is brought into press- contact with the drum 1. Toner T stuck to the drum 1 after development is carried to a transfer area. The voltage of a polarity on the side to which the toner T is transferred is applied to the drum 1 by the electric discharge electrode 51 (tungsten wire 511) of a transfer means 5 which is brought into contact with the drum 1 synchronously with a toner image. Thus, the toner T is moved to a recording material P and the toner image is transferred, and the toner T on the material P is fixed by a fixing means 6 after the material p is separated from the drum 1, and after the material P is ejected to outside, the surface of the drum 1 is cleaned by a cleaning means 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus such as a copying machine, an optical printer, a facsimile, etc. which employs an electrophotographic system.

[0002]

2. Description of the Related Art In a conventional image forming apparatus using an electrophotographic system, an image is formed while erasing a photoreceptor memory by exposure or transfer with a charge removing light. However, JP-A-4-256
977 proposes an image forming apparatus in which the charge removal process is abolished from the viewpoint of cost reduction and durability of the transfer member. Japanese Patent Application Laid-Open No. H11-95577 proposes that the transfer output is changed depending on the process speed. This is because the same amount of charge per unit area of the recording material is used to obtain stable transferability and good image quality. Further, in Japanese Patent Application Laid-Open No. 8-122678, a plurality of resolution images can be output depending on the rotation speed of a polygon motor as an exposure means, laser power, and modulation time.

[0003]

However, since JP-A-4-256977 has a transfer belt for obtaining a full-color image, its structure and control itself are complicated, and the total cost of this system itself is reduced. Not only is it not sufficient for down and improvement in durability, but there is no mention of transfer means other than the belt.

Japanese Patent Application Laid-Open No. H11-95577 does not describe the effects and problems of the photoreceptor memory, and the transfer means is a belt type. Therefore, in the case of a corotron or the like, simply changing the output in accordance with the process speed may cause a defect not only in the photoconductor memory but also in the transferability itself. Furthermore, when a low process speed is used as a reference, twice the current amount is required when the speed is doubled, and three times the current amount is required when the speed is tripled. In the case of an electrode or the like, the amount of generated ozone increases.

In Japanese Patent Application Laid-Open No. 8-122678, the resolution conversion method is performed by the exposure means. However, there are a number of switching means and their control, and the system itself becomes complicated and the cost increases.

The present invention has been made in view of the above-mentioned conventional problems, and in order to solve the above problems,
Designed under more detailed charging, exposure, and transfer conditions, without using a charge elimination process to reduce costs, while having multiple process speeds to obtain multiple resolutions, it is low-cost, simple, An object of the present invention is to provide an image forming apparatus capable of suppressing the photoconductor memory at any multiple process speeds and resolutions while suppressing the complexity and size of the apparatus.

[0007]

The present invention has the following arrangement to achieve the above object. The present invention provides a charging unit for charging a photoreceptor, an exposure unit for exposing the photoreceptor charged by the charging unit to form an electrostatic latent image, and an electrostatic latent image formed on the photoreceptor. Developing means for developing;
A transfer unit for transferring a developed toner image to the recording material in contact with the peripheral surface of the photoconductor is provided, and a charge elimination process for erasing a charging history of the photoconductor as a process before the charging unit is omitted. In the image forming apparatus that switches to a plurality of process speeds, a drive current value M1 of the charging unit at the time of image formation at the first process speed V1 and a second current value M1 larger than the first process speed V1. The relationship is set or controlled so that the relational expression of the drive current value M2 of the charging means at the time of image formation at the process speed V2 satisfies M2 ≧ (0.9 + 0.1 × V2 / V1) × M1. An image forming apparatus. According to the present invention, the photoreceptor memory due to exposure and transfer can be suppressed by charging by the charger.

Further, the present invention provides a charging unit for charging a photoreceptor, an exposing unit for exposing the photoreceptor charged by the charging unit to form an electrostatic latent image, and an exposing unit formed on the photoreceptor. A developing unit for developing an electrostatic latent image; and a transfer unit for transferring a developed toner image to the recording material in contact with the peripheral surface of the photoconductor. In an image forming apparatus that switches to a plurality of process speeds by omitting a charge removal step of erasing a charging history, a drive current value T1 of the transfer unit when an image is formed at a first process speed V1, Process speed V
The relational expression of the drive current value T2 of the transfer means at the time of image formation at the second process speed V2 greater than 1 is T2 ≧
An image forming apparatus is set or controlled so as to satisfy (0.9 + 0.1 × V2 / V1) × T1. According to the present invention, it is possible to suppress photoconductor memory due to transfer.

Further, the present invention provides a charging means for charging a photoreceptor, an exposing means for exposing the photoreceptor charged by the charging means to form an electrostatic latent image, and a photoreceptor formed on the photoreceptor. Developing means for developing an electrostatic latent image, and transfer means for transferring a developed toner image to the recording material in contact with the peripheral surface of the photoreceptor; Omitting the static elimination process to erase the charging history,
In an image forming apparatus that switches to a plurality of process speeds, a driving current value M1 of the charging unit at the time of image formation at a first process speed V1 and a second process speed higher than the first process speed V1 The relational expression of the driving current value M2 of the charging means at the time of image formation by V2 is M2 ≧ (0.9
+ 0.1 × V2 / V1) × M1 and the drive current value T of the transfer means at the time of image formation at the first process speed V1.
1 and the drive current value T2 of the transfer means at the time of image formation at the second process speed V2 higher than the first process speed V1 is T2 ≧ (0.9 + 0.1 × V2 / V1)
The image forming apparatus is set or controlled so as to satisfy × T1. According to the present invention, higher image quality can be achieved. Further, it is possible to suppress the photoreceptor memory due to exposure and transfer without being affected by the exposure conditions necessary for achieving high image quality, particularly high resolution.

In the present invention, the charging means may include a wire electrode or a saw-tooth electrode as a corona discharge electrode. The charger is a means for charging the photoreceptor, and can be used to suppress the photoreceptor memory by setting appropriate conditions.

Further, in the present invention, the charging case of the charging means may be provided with a cutout on the upstream side in the photosensitive member moving direction. According to the present invention, the charging case of the charging unit is provided with cutouts to suppress stagnation of the ozone generated by the discharge of the charger near the photoconductor, and to reduce the image of the photoconductor memory or the like due to the photoconductor ozone damage. Deterioration can be prevented. Further, by expanding the width of the voltage control member in accordance with the cutting, the capacity as a charger can be increased, and the photoconductor memory can be suppressed.

In the present invention, the width L1 of the voltage control member (Grid) of the charging means is wider than the width L2 of the charging case, and protrudes beyond the width of the charging case on the side where the cutout portion is provided. Can be. According to the present invention, the charging case of the charging unit is provided with cutouts to suppress stagnation of the ozone generated by the discharge of the charger near the photoconductor, and to reduce the image of the photoconductor memory or the like due to the photoconductor ozone damage. Deterioration can be prevented. Further, by expanding the width of the voltage control member in accordance with the cutting, the capacity as a charger can be increased, and the photoconductor memory can be suppressed.

Further, in the present invention, the projecting amount of the voltage control member (Grid) of the charging hand throw can be made longer than the cutting length of the charging case. According to the present invention, the charging case of the charging unit is provided with a cutout,
It is possible to suppress ozone generated by discharge of the charger near the photoconductor, and to prevent image deterioration of a photoconductor memory or the like due to photoconductor ozone damage. Further, by expanding the width of the voltage control member in accordance with the cutting, the capacity as a charger can be increased, and the photoconductor memory can be suppressed.

In the present invention, the transfer means may include a wire electrode or a saw-tooth electrode as a corona discharge electrode. According to the present invention, the transfer device is a means for transferring the toner on the photoconductor to the recording material, and it is possible to suppress the photoconductor memory by using these and setting appropriate conditions.

Further, in the present invention, it is possible to have a time when the control signal is turned off immediately after the output of the transfer means is started. According to the present invention, by applying a stepwise current to the transfer unit, the transfer output is started up, so that the time to reach the transfer region at the leading end of the recording material,
It is possible to suppress the transfer memory when the delay is longer than the transfer output rise time.

Further, in the present invention, the transfer output to the transfer means can be lowered until the rear end of the recording material has passed through the transfer means and within the rear end void.

Further, according to the present invention, there is provided a charging means for charging a photoreceptor, an exposing means for exposing the photoreceptor charged by the charging means to form an electrostatic latent image, and a photoreceptor formed on the photoreceptor. Developing means for developing an electrostatic latent image; and transfer means for transferring the developed toner image to the recording material in contact with the peripheral surface of the photoconductor, wherein the charging of the photoconductor is performed as a pre-process of the charging means. Omit the static elimination process to erase the history,
In an image forming apparatus that switches to a plurality of process speeds, a drive current value M1 of the charging unit when an image is formed at a first process speed V1, and a second process speed higher than the first process speed V1 The relational expression of the drive current value M2 of the charging means at the time of image formation with V2 is M2 ≧ (0.9+
An image forming apparatus characterized in that the resolution is changed by switching the process speed while setting or controlling so as to satisfy 0.1 × V2 / V1) × M1.

Further, according to the present invention, there is provided a charging means for charging a photoreceptor, an exposing means for exposing the photoreceptor charged by the charging means to form an electrostatic latent image, and an exposing means formed on the photoreceptor. A developing unit for developing an electrostatic latent image; and a transfer unit for transferring a developed toner image to the recording material in contact with the peripheral surface of the photoconductor. In an image forming apparatus that switches to a plurality of process speeds by omitting a charge removal step of erasing a charging history, a drive current value T1 of the transfer unit when an image is formed at a first process speed V1, Process speed V
The relational expression of the drive current value T2 of the transfer means at the time of image formation at the second process speed V2 greater than 1 is T2 ≧
An image forming apparatus characterized in that the resolution is changed by switching the process speed while setting or controlling so as to satisfy (0.9 + 0.1 × V2 / V1) × T1.

Further, according to the present invention, there is provided a charging means for charging a photoreceptor, an exposing means for exposing the photoreceptor charged by the charging means to form an electrostatic latent image, and an exposing means formed on the photoreceptor. Developing means for developing an electrostatic latent image, and transfer means for transferring the developed toner image to the recording material in contact with the peripheral surface of the photoreceptor; In an image forming apparatus that switches to a plurality of process speeds by omitting a charge removal step of erasing a charge history, a drive current value M1 of the charging unit when an image is formed at a first process speed V1, Process speed V
The relational expression of the drive current value M2 of the charging means at the time of image formation at the second process speed V2 greater than 1 is M2 ≧
(0.9 + 0.1.times.V2 / V1) .times.M1, the drive current value T1 of the transfer means at the time of image formation at the first process speed V1, and the second current value larger than the first process speed V1. The relational expression of the drive current value T2 of the transfer means at the time of image formation at the process speed V2 is T2 ≧ (0.9 + 0.1 × V
An image forming apparatus characterized in that the resolution is changed by switching the process speed while setting or controlling to satisfy 2 / V1) × T1.

Further, in the present invention, at least one of claims 11, 12, and 13, the first resolution D1 at the time of image formation at the first process speed V1;
The relationship with the second resolution D2 at the time of image formation at the second process speed V2 higher than the first process speed V1 is V1
It can be set or controlled so as to satisfy × D1 = V2 × D2.

In the present invention, the second process speed V2 can be set or controlled to be an integral multiple of the first process speed.

That is, according to the present invention, by adopting the above-described structure, when a plurality of process speeds for obtaining a high resolution are provided, the diameter of the photosensitive member is not limited, and the charge removing process is omitted to eliminate the photosensitive member. An image forming apparatus that suppresses memory can be realized.

[0023]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is an explanatory diagram of an image forming method using the two-component developing method of the first embodiment. The basic configuration includes charging, exposure, development, transfer, fixing, and cleaning steps.

The photosensitive drum 1 having a diameter of 30 mm has an arrow S
It is provided so as to be rotatable in one direction. The surface of the photoreceptor drum 1 is uniformly charged to a predetermined charge amount by a corona charger or a contact roller charger as a charging unit 2, and a predetermined electrostatic latent image potential is formed by the exposure unit 3 to form an electrostatic latent image. Carry the image. The photoconductor drum 1 includes a conductive substrate made of metal or resin, an undercoat layer formed on the surface thereof, and a photosensitive layer formed thereon.
The photosensitive layer includes a relatively thin carrier generation layer (CGL) formed on the undercoat layer and a relatively thin carrier transfer layer (CT) mainly composed of polycarbonate or the like formed on the outermost layer.
L). Carriers are generated in the carrier generating layer by the exposure, and the charges on the photosensitive drum 1 are canceled by the carriers to form the electrostatic latent image potential.

The electrostatic latent image carried on the photosensitive drum 1 is
As the drum 1 rotates, the drum 1 is transported to a developing area in contact with the developer carrier 41 of the developing device 4. The developer carrier 41 that rotates in the direction of the arrow S3 opposite to the direction S1 is pressed against the photosensitive drum 1. However, the rotation direction of the developer carrier is not limited to this. Then, the toner T carried on the developing agent carrier 41 moves and adheres according to the electrostatic latent image on the photoconductor drum 1, whereby the electrostatic latent image is visualized and a phenomenon occurs. Developer carrier 41
, A predetermined bias voltage is applied from a connected power supply (not shown).

After the development, the toner T adhered to the photosensitive drum 1 is transported to a predetermined transfer area. A recording material P such as paper is supplied to the transfer area by a paper supply unit, and the recording material P contacts the photosensitive drum 1 in synchronization with the toner image. The transfer means 5 provided in the transfer area includes a charger type having a high voltage power supply and a contact roller type.
Is applied to the photosensitive drum 1. As a result, the toner T moves to the recording material P, and the toner image is transferred. After the recording material P is separated from the photosensitive drum by the peeling means, the toner T on the recording material P is fixed by the fixing means 6 by, for example, heat melting or pressure. Then, the paper is discharged outside the apparatus. Further, the surface of the photosensitive drum 1 after the transfer is cleaned by the cleaning unit 7.

As shown in FIG. 2A, the charging means 2
A sawtooth electrode 211 (detailed view is described in FIG. 5) is used as the discharge electrode 21, and a charging case 22 having a width L2 (= 10 mm) is covered so as to cover the electrode 211.
The upstream case wall of the charging case 22 in the rotation direction of the photosensitive drum 1 is provided with a cutout having a length L3 = (3 mm), so that the distance between the charging case 22 and the photosensitive drum 1 is widened. Further, a charging control member 23 for controlling the charging voltage of the photosensitive drum 1 is provided between the photosensitive drum 1 and the photosensitive drum 1.
(= 14 mm) of the charging control member 23
Extending in the direction of the case wall where the cutout portion is provided. The transfer means 5 uses a corona discharge method,
A tungsten wire 511 is used as the discharge electrode 51.

The charging means 2 and the transfer means 5 of the present invention are controlled by a constant current, so that the respective current values can be adjusted independently. Further, the output level can be raised stepwise by using a current application control signal (ON / OFF) as a stepwise transfer current application means of the transfer means 5 and using a switching circuit mechanism. In addition, there is a driving means (not shown), which can also arbitrarily adjust the speed and freely change the process speed.

The image forming apparatus of the first embodiment was evaluated. The evaluation of the photoreceptor memory was such that the exposure memory was solid black at the leading end 10 mm of the recording material P, but halftone was printed in the latter half, and the transfer memory was full-tone halftone printing, and the rotation of the photosensitive drum 1 was performed one revolution. The intermediate density difference between the eyes and the second rotation was visually evaluated in five steps. In this five-step evaluation, there is a static elimination process, 5 points when no memory is generated, 4 points when faintly understood, 3 points when memory is confirmed, and 2 points when clear, When the memory was confirmed even after two rotations of the photosensitive drum (that is, after about 188 mm from the leading end of the recording material), one point was determined, and the allowable range was three points or more.

First, as a basic condition, the process speed is set to 88.
mm / s, the current value of the charging means 2 is 560 μA,
When the transfer means 5 was set to 260 μA, the transfer and exposure memories were at the three-point level. When the process speed was set to 122 mm / s under these conditions, the memory evaluation was at a two-point level and deteriorated. Then, the current value of the charging means 2 was set to 585 μA and further increased to 600 μA. As a result, the memory evaluation was 3 points and further improved to 4 points.
Table 1 shows the memory evaluation results.

[Table 1]

The current of about 90% of the charging means 2 under the basic conditions is the minimum value, that is, the minimum value at which the photosensitive drum 1 can be charged by the control of the charging control member 23.
Stable charging is performed by the 0% current. Therefore, by increasing or decreasing the remaining 10% of the current value according to the process speed, stable charging of the photosensitive drum 1 and suppression of the photosensitive memory can be realized.

Next, in the second embodiment, using the same image forming apparatus as that of the first embodiment shown in FIG.

First, as a basic condition, the process speed is set to 12
When the current value of the charging means 2 was 585 μA and that of the transfer means 5 was 260 μA, the transfer and exposure memories were at three points. When the process speed is 88 mm / s under these conditions, the memory evaluation is 2
It has deteriorated to the point level. Then, the current value of the transfer unit 5 was set to 250 μA and further reduced to 200 μA. As a result, the memory evaluation was 3 points and further improved to 4 points. Table 2 shows the results of the memory evaluation.

[Table 2]

Under the basic conditions, the current of about 90% of the transfer means 5 is the minimum, that is, the energy necessary for the discharge itself and the electric movement of the toner T on the photosensitive drum 10 via the recording material P can be obtained. This is the minimum possible value, and stable transfer is performed by approximately 10% of the other current. Therefore, by increasing or decreasing the remaining 10% of the current value according to the process speed, stable transfer and suppression of the photosensitive memory were realized.

Next, in the third embodiment, in the same image forming apparatus as in the first embodiment, image deterioration was confirmed by ozone generated by the discharge of the charging unit 2. The process speed is 88 mm / s, and the current value of the charging means 2 is 560
μA, and that of the transfer means 5 was set to 260 μA. As a method, in a low humidity environment where ozone is not easily hydrolyzed, the photosensitive drum 10 was subjected to idle rotation exposure for 8 hours, and the same memory evaluation as in Embodiment 1 was performed. It was a three-point memory that was almost the same.

On the other hand, the charging means 2 used is, as shown in FIG. 2B, a charging case 22 having no notch, and a charging control member 23 does not protrude from the width of the charging case 22 and is directly below the charging case 22. When a charging means was prepared and the same ozone exposure was confirmed, the exposure and the transfer memory did not disappear even if the photosensitive drum 1 was rotated twice, and the evaluation point was deteriorated to a level of one point. Table 3 shows the memory evaluation results.

[Table 3]

The above-mentioned result is obtained because the ozone generated by the discharge from the discharge electrode 21 of the charging means 2 causes the photosensitive drum 1
Of the CTL charge retention capability of the CGL, or damage to the CGL itself to form a space charge, thereby generating an electric field and increasing the charge injection from the base material. That is, it is indispensable to efficiently move the ozone generated by the discharge away from the photosensitive drum 1. In addition, by widening the charge control member 23 for controlling the charging of the photosensitive drum 1, the charging performance was improved, and the photosensitive memory could be suppressed.

Next, in the fourth embodiment, as shown in FIG. 3B, in the image forming apparatus which outputs the transfer current at a certain timing at a time as shown in FIG. When the timing of entering the transfer area of the recording material P caused by the state, the use environment conditions, and the solid variation of the image forming apparatus itself is delayed, the ion flow generated from the transfer unit 5 directly acts on the photosensitive drum 1 to perform halftone printing. In some cases, the transfer memory is about 94% from the leading end of the recording material P.
mm (one circumference of the photosensitive drum 1). However, as shown in FIG. 3 (a), when the transfer output current is gradually increased by once sending the start signal and then sending the off signal once, even if the inrush timing of the recording material P is delayed, the dark streaks Did not appear.

That is, the dark streak due to this transfer memory is
This is due to the rapid rise of the transfer output, and it is necessary to gradually increase the transfer output at the time of the rise.

In the fifth embodiment, the following conditions were set as the conditions for cutting off the transfer output in the basic conditions of the first embodiment. Even when the interval between the recording materials P is shorter than the circumferential length of the photosensitive drum 1, In the continuous printing, a good image having no transfer memory could be obtained.

As a method, the timing at which the transfer output is cut off is set earlier than the trailing end of the recording material P in consideration of the variation in the passage of the recording material P. However, in order to avoid the trailing edge image loss, the time is set within the trailing edge void even if it is cut earlier. When the transfer is cut on the basis of the rear end of the recording material P [C], and when the transfer is cut in consideration of the rear end void [B],
FIG. 4A shows the control signal and the transfer output current under the three conditions [A] when the transfer is cut off too early, and FIG. 4B shows the transfer memory width and the transfer loss width.

In the sixth embodiment, an image forming apparatus similar to that of the first embodiment is used. First, as a basic condition, the process speed is set to 122 mm / s, and the current value of the charging unit 2 is set to 600 μA.
By setting the transfer means 5 to 260 μA, an image having a resolution of 600 dpi was obtained. Further, using the same image forming apparatus, without changing the rotation speed of the polygon mirror of the exposure unit 3,
The process speed was set to 61 mm / s, the current value of the charging unit 2 was set to 545 μA, that of the transfer unit 5 was set to 235 μA, and an image was output at a resolution of 1200 dpi. That is, an image having a resolution inversely proportional to the process speed could be obtained without performing a complicated modification or switching of the exposure unit 3.

[0043]

According to the present invention, there is provided a charging means for charging a photoreceptor, an exposing means for exposing the photoreceptor charged by the charging means to form an electrostatic latent image, and an exposing means formed on the photoreceptor. Developing means for developing the developed electrostatic latent image, and transferring means for transferring the developed toner image to the recording material in contact with the peripheral surface of the photoreceptor, and a plurality of process speeds for forming an image. In an image forming apparatus having a charge elimination device for erasing the charging history of the photoconductor in a process preceding the charging unit, the current of a charging unit or a transfer unit is optimally set or controlled by a process speed. Thereby, the photoreceptor memory due to exposure and transfer can be suppressed. ｛Claim 1
~ 13 (especially 1 and 2)｝

Further, in the present invention, the charging case of the charging means is provided with cutouts, so that damage to the photoreceptor due to stagnation of ozone generated by discharging of the charging unit 2 can be reduced, and image deterioration can be prevented. Further, by increasing the width of the voltage control member in response to the cutting, the charging performance of the photoconductor is improved, and the photoconductor memory due to exposure or transfer in a low humidity environment or at the life end of the photoconductor can be suppressed.
(Corresponding to claims 5 to 7)

Further, in the present invention, by optimizing the method of starting the transfer means 5 and the timing of the fall, the timing of entering the transfer area at the leading end of the recording material P,
Even if the paper ejection timing at the rear end is shifted, image deterioration due to the transfer memory can be eliminated, and the transfer memory can be suppressed. (Corresponding to claims 9 and 10)

Further, in the present invention, it is possible to suppress the photosensitive memory and to perform resolution conversion and image formation by switching the process speed without having complicated remodeling and switching means of the exposure means 3. (Corresponding to claims 11 to 13)

In the present invention, the first resolution D1 at the time of image formation at the first process speed V1 and the second resolution D1 at the time of image formation at the second process speed V2 higher than the first process speed V1. The relationship with the resolution D2 is V1 × D1 =
By setting or controlling so as to satisfy V2 × D2, it is possible to easily form images with a plurality of resolutions without complicated control while suppressing the photoconductor memory. (Corresponding to claim 14)

In the present invention, V1 × D1 =
When V2 × D2 is satisfied and V1 <V2, these relationships are set or controlled so as to satisfy n × V1 = V2; (n = integer). Resolution, 300, 600, 1200, 24
Conversion of 00 dpi or the like can be easily performed.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an electrophotographic process.

FIGS. 2A and 2B are explanatory diagrams of a charging unit. FIG. 2A is an explanatory diagram of the present embodiment, and FIG. 2B is an explanatory diagram of a comparative embodiment.

FIGS. 3A and 3B are illustrations of control of the present embodiment, and FIG. 3B is an illustration of a comparative embodiment, regarding output startup of a transfer unit.

FIGS. 4A and 4B are diagrams illustrating a transfer memory and an image loss caused by an output fall timing of a transfer unit according to the embodiment;
It is explanatory drawing of control and output, (b) is explanatory drawing of an image evaluation result.

FIG. 5 is an explanatory diagram of a saw blade electrode of the present embodiment.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photosensitive drum 2 charging means (charging part) 21 discharge electrode 211 saw-tooth electrode 22 charging case 23 charging control member L1 charging control member width L2 charging case width L3 charging case cutout length 3 exposure means 4 phenomenon device 41 developing device 41 development Agent carrier 5 Transfer unit (transfer unit) 51 Discharge electrode (transfer unit) 511 Tandesten wire 6 Fixing unit 7 Cleaning unit T Toner P Recording material

Claims (15)

[Claims] A charging unit configured to charge the photoconductor, an exposure unit configured to expose the photoconductor charged by the charging unit to form an electrostatic latent image, and an electrostatic latent image formed on the photoconductor. Developing means for developing the toner image, and a transfer means for transferring the developed toner image to the recording material in contact with the peripheral surface of the photoreceptor, and erasing the charging history of the photoreceptor as a process preceding the charging means. An image forming apparatus that switches to a plurality of process speeds by omitting a charge removing step, wherein a drive current value M1 of the charging unit when forming an image at a first process speed V1, and a first process speed V1 Setting such that the relational expression of the drive current value M2 of the charging means at the time of image formation at the second process speed V2 which is higher than the above satisfies M2 ≧ (0.9 + 0.1 × V2 / V1) × M1; or Features to control Image forming apparatus. 2. A charging device for charging a photoconductor, an exposure device for exposing the photoconductor charged by the charging device to form an electrostatic latent image, and an electrostatic latent image formed on the photoconductor. And a transfer unit for transferring a developed toner image to the recording material that is in contact with the peripheral surface of the photoconductor, and erases a charging history of the photoconductor as a process preceding the charging unit. An image forming apparatus that performs switching to a plurality of process speeds by omitting the charge removal process that is performed, wherein the drive current value T1 of the transfer unit when forming an image at the first process speed V1 and the first process speed V1 Is set or controlled so that the relational expression of the drive current value T2 of the transfer means at the time of image formation at the second process speed V2 satisfies T2 ≧ (0.9 + 0.1 × V2 / V1) × T1. Is characterized by Image forming apparatus. A charging unit configured to charge the photoconductor, an exposure unit configured to expose the photoconductor charged by the charging unit to form an electrostatic latent image, and an electrostatic latent image formed on the photoconductor. Developing means for developing the toner image, and a transfer means for transferring the developed toner image to the recording material in contact with the peripheral surface of the photoconductor. In an image forming apparatus that switches to a plurality of process speeds by omitting a charge removal process for erasing, a drive current value M1 of the charging unit when forming an image at a first process speed V1, a first process speed V1 The relational expression of the drive current value M2 of the charging means at the time of image formation at the second process speed V2 which is larger than the first process speed satisfies M2 ≧ (0.9 + 0.1 × V2 / V1) × M1. Before image formation by V1 The relational expression between the drive current value T1 of the transfer means and the drive current value T2 of the transfer means at the time of image formation at the second process speed V2 higher than the first process speed Vl is T2 ≧ (0.9 + 0.1 × V2 / V1) × T1 The image forming apparatus is set or controlled so as to satisfy: 4. An image forming apparatus according to claim 1, wherein said charging means includes a wire electrode or a saw-tooth electrode as a corona discharge electrode. 5. An image forming apparatus according to claim 4, wherein said charging case of said charging means is provided with a cutout on an upstream side in a photosensitive member moving direction. 6. The charging device according to claim 5, wherein the width L1 of the voltage control member of the charging unit is wider than the width L2 of the charging case.
An image forming apparatus characterized in that it projects beyond the width of the charging case on the side where the notch is provided. 7. The image forming apparatus according to claim 6, wherein a protrusion amount of the voltage control member of the charging hand throw is longer than a cutting length of the charging case. 8. The image forming apparatus according to claim 2, wherein the transfer unit includes a wire electrode or a saw-tooth electrode as a corona discharge electrode. 9. The image forming apparatus according to claim 2, wherein the control signal is turned off immediately after the output of the transfer unit is started. 10. The image forming apparatus according to claim 2, wherein a transfer output to the transfer unit falls until a rear end of the recording material has passed through the transfer unit and within a rear end void. 11. A charging unit for charging a photoconductor, an exposure unit for exposing the photoconductor charged by the charging unit to form an electrostatic latent image, and an electrostatic latent image formed on the photoconductor. And a transfer unit for transferring a developed toner image to the recording material that is in contact with the peripheral surface of the photoconductor, and erases a charging history of the photoconductor as a process preceding the charging unit. An image forming apparatus that performs switching to a plurality of process speeds by omitting the charge removal process that is performed, wherein the drive current value M1 of the charging unit at the time of image formation at the first process speed V1 and the first process speed V1 Is set or controlled so that the relational expression of the drive current value M2 of the charging means at the time of image formation at the second process speed V2 satisfies M2 ≧ (0.9 + 0.1 × V2 / V1) × M1. While a professional An image forming apparatus characterized by changing the resolution by switching the scan speed. 12. A charging unit for charging a photoconductor, an exposure unit for exposing the photoconductor charged by the charging unit to form an electrostatic latent image, and an electrostatic latent image formed on the photoconductor. And a transfer unit for transferring a developed toner image to the recording material in contact with the peripheral surface of the photoconductor, and a charging history of the photoconductor as a process preceding the charging unit is provided. In an image forming apparatus that switches to a plurality of process speeds by omitting an erasing process for erasing, a drive current value T1 of the transfer unit at the time of image formation at a first process speed V1, and a first process speed V1 Setting such that the relational expression of the drive current value T2 of the transfer means at the time of image formation at the second process speed V2 larger than T2 satisfies T2 ≧ (0.9 + 0.1 × V2 / V1) × T1; or While controlling, professional An image forming apparatus, wherein the resolution is changed by switching the access speed. 13. A charging device for charging a photoconductor, an exposure device for exposing the photoconductor charged by the charging device to form an electrostatic latent image, and an electrostatic latent image formed on the photoconductor. Developing means for developing the toner image, and a transfer means for transferring the developed toner image to the recording material in contact with the peripheral surface of the photoreceptor, and erases the charging history of the photoreceptor as a process preceding the charging means. An image forming apparatus that performs switching to a plurality of process speeds by omitting a charge removal process, wherein a drive current value M1 of the charging unit when forming an image at a first process speed V1 and a first process speed V1 The relational expression of the drive current value M2 of the charging means at the time of image formation at the second process speed V2 satisfies M2 ≧ (0.9 + 0.1 × V2 / V1) × M1, and the first process speed V1 Before imaging by The relational expression between the drive current value T1 of the transfer means and the drive current value T2 of the transfer means at the time of image formation at the second process speed V2 higher than the first process speed Vl is T2 ≧ (0.9 + 0. An image forming apparatus wherein the resolution is changed by switching the process speed while setting or controlling so as to satisfy 1 × V2 / V1) × T1. 14. The claim 11, claim 12, or claim 13
In at least one of the first, the first resolution D at the time of imaging at the first process speed V1
setting or controlling such that the relationship between 1 and the second resolution D2 at the time of image formation at the second process speed V2 higher than the first process speed V1 satisfies V1 × D1 = V2 × D2. An image forming apparatus comprising: 15. The image forming apparatus according to claim 14, wherein the second process speed V2 is set or controlled to be an integral multiple of the first process speed.