JPH11174751A - Image forming device - Google Patents

Image forming device

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Publication number
JPH11174751A
JPH11174751A JP9340986A JP34098697A JPH11174751A JP H11174751 A JPH11174751 A JP H11174751A JP 9340986 A JP9340986 A JP 9340986A JP 34098697 A JP34098697 A JP 34098697A JP H11174751 A JPH11174751 A JP H11174751A
Authority
JP
Japan
Prior art keywords
image
developing
bias voltage
ac component
developing bias
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
JP9340986A
Other languages
Japanese (ja)
Inventor
Makoto Hirota
真 廣田
Original Assignee
Fuji Xerox Co Ltd
富士ゼロックス株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Fuji Xerox Co Ltd, 富士ゼロックス株式会社 filed Critical Fuji Xerox Co Ltd
Priority to JP9340986A priority Critical patent/JPH11174751A/en
Publication of JPH11174751A publication Critical patent/JPH11174751A/en
Pending legal-status Critical Current

Links

Abstract

(57) [Problem] To suppress the occurrence of density fluctuation due to an AC component when developing with a developing bias voltage in which an AC component is superimposed on a DC component. A power supply (56) is provided on a sleeve (32B) of a developing roller (32).
As a result, a developing bias voltage in which an AC component is superimposed on a DC component is applied. The developing bias voltage is divided by a voltage divider 58, the phase is changed by a phase adjuster 60, and input to the calculator 62 as a bias signal. The arithmetic unit 62 corrects the video signal input from the video signal generator 64 so that the emission amount from the LD 18 increases as the level of the bias signal decreases, and the emission amount decreases as the level increases. Output. The amount of phase change by the phase adjuster 60 is adjusted in advance so that banding does not occur on the halftone image. As a result, the development electric field becomes constant irrespective of the periodic fluctuation of the development bias voltage due to the AC component, and the occurrence of banding is suppressed.

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, and more particularly, to an image carrier which is scanned and exposed to form an electrostatic latent image.
The present invention relates to an image forming apparatus that forms an image by developing an electrostatic latent image using a developer while a developing bias voltage in which an AC component is superimposed on a DC component is applied.

[0002]

2. Description of the Related Art An electrophotographic image forming apparatus includes an image carrier that is moved in a predetermined direction. After charging the surface of the image carrier with a charger,
The surface of the image carrier is exposed according to an image by an exposure device. Since the potential of the exposed portion on the surface of the image carrier decreases in accordance with the amount of irradiation light, an electrostatic latent image is formed on the surface of the image carrier. A developing bias voltage is applied to the developing device, and toner is caused to adhere to the exposed portion on the surface of the image carrier by a potential difference between the applied developing bias voltage and the exposed portion on the surface of the image carrier (that is, a developing electric field). As a result, the electrostatic latent image is developed, and a toner image is formed on the image carrier. This toner image is transferred to a transfer material, and the toner image transferred to the transfer material is fixed, whereby an image is formed on the transfer material.

In the above-described image forming apparatus, it is common to apply a voltage in which an AC component is superimposed on a DC component to a developing device as a developing bias voltage. However, when the developing bias voltage is a voltage in which an AC component is superimposed on a DC component, in addition to an amount of toner corresponding to the DC component, an amount of toner corresponding to the AC component whose voltage changes periodically also carries an image. As a result, there is a problem that the density of an image (toner image) fluctuates along the moving direction of the image carrier (referred to as the direction of development by the developing device, the process direction). This change in density is clearly recognized as a dark and light stripe pattern (so-called banding) particularly when a halftone image is formed.

Japanese Patent Application Laid-Open No. 6-348137 describes that banding occurs when the frequency of the AC component included in the developing bias voltage is low. It also describes that the cost of the image forming apparatus is increased due to the loading loss. Since whether or not banding occurs also depends on the moving speed (rotation speed) of the image carrier, if the moving speed of the image carrier is increased to achieve a higher image forming speed, the occurrence of banding is reduced. In order to avoid this, it is necessary to greatly increase the frequency of the AC component, which causes a problem of increasing the cost of the image forming apparatus.

Japanese Patent Application Laid-Open No. 181768/1990 discloses that uneven exposure caused by fluctuations in the moving speed of a photosensitive member (image carrier) is corrected by increasing or decreasing the amount of light beam irradiation. ing.

The present invention has been made in view of the above-described facts. When developing is performed by a developing bias voltage in which an AC component is superimposed on a DC component, a density variation occurs due to the AC component included in the developing bias voltage. It is an object of the present invention to obtain an image forming apparatus capable of suppressing such a problem.

[0007]

According to another aspect of the present invention, there is provided an image forming apparatus comprising: an image carrier; a charging unit configured to charge the image carrier; An exposure unit that scans and exposes the modulated light on the image carrier charged by the charging unit to form an electrostatic latent image on the image carrier; and a developing bias in which an AC component is superimposed on a DC component. A developing unit that develops the electrostatic latent image formed on the image carrier using a developer while a voltage is applied, and a developing bias voltage based on the AC component when the developing unit performs development. Adjusting means for adjusting the exposure amount when the exposing means scans and exposes the image carrier, so that the influence of the periodic fluctuation of n is cancelled.

According to the first aspect of the present invention, the developing unit applies the developer to the electrostatic latent image formed on the image carrier while a developing bias voltage in which an AC component is superimposed on a DC component is applied. And develop. Since this developing bias voltage contains an AC component, the magnitude of the developing bias voltage periodically fluctuates at the same frequency and phase as the AC component. Therefore, according to the first aspect of the present invention, the exposure unit scans and exposes the image carrier on the image carrier so that the influence of the periodic fluctuation of the development bias voltage due to the AC component when the development unit performs development is canceled. Adjustment means for adjusting the exposure amount is provided.

The adjustment by the adjusting means is, specifically,
A portion of the image forming surface of the image carrier where development is performed by the developing unit when the developing bias voltage is relatively low has a low potential at a portion exposed by the exposing unit, and the developing bias voltage is relatively high. By adjusting the exposure amount by periodically changing the light amount of the light applied to the image carrier so that the potential of the portion exposed by the exposure unit becomes higher for the portion where the development is performed by the developing unit. realizable.

By adjusting the exposure amount, for example, when a halftone image having a constant density is formed on the image carrier,
The development electric field, which is the difference between the potential of the exposed portion and the development bias voltage, becomes substantially constant by periodically changing the potential of the portion exposed by the exposure means on the image carrier. The effect of the periodic fluctuation is canceled, and it is possible to prevent the halftone image developed by the developing unit from having a periodic uneven density. In addition, even when an image other than a halftone image is formed, it is possible to prevent a density variation corresponding to a periodic variation of the developing bias voltage from being applied. Therefore, according to the first aspect of the invention, when the development is performed with the developing bias voltage in which the DC component is superimposed on the DC component, it is possible to suppress the occurrence of the density fluctuation due to the AC component included in the developing bias voltage. .

In order to suppress the density fluctuation due to the AC component included in the developing bias voltage, the adjusting means adjusts the exposure amount so that the exposure amount periodically changes in the same cycle as the AC component. There is a need. With this in mind,
The adjusting means is configured to adjust the amount of exposure by the exposing means based on a signal obtained by dividing the developing bias voltage applied to the developing means and adjusting the phase, as described in claim 2. Is preferred. Accordingly, the exposure amount is periodically changed at the same cycle as the AC component without complicating the configuration such as providing a time measuring means for periodically changing the exposure amount at the same cycle as the AC component. The exposure can be adjusted as described above.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. In the following, a description will be given using a numerical value that does not hinder the present invention as an example, but the present invention is not limited to the numerical value described below. In this embodiment, an image forming apparatus (a so-called printer) that forms an image represented by received data on recording paper based on data received from a computer will be described as an example of an image forming apparatus according to the present invention.

As shown in FIG. 1, in an image forming apparatus 10 according to the present embodiment, a photosensitive drum 12 as an image carrier is provided at a substantially central portion of a casing 10A. The photosensitive drum 12 has a cylindrical shape and an insulating photoconductive layer formed on a peripheral surface thereof. The photosensitive drum 12 is rotated at a constant speed (for example, a peripheral speed of 300 mm / sec) in a direction indicated by an arrow A in FIG. As shown in FIG. 2, the main body of the photosensitive drum 12 is grounded.

A charger (charging roller) 14 is disposed above the photosensitive drum 12. The charger 14 uniformly charges the peripheral surface of the photosensitive drum 12 to a predetermined potential (for example, 400 V). Position spaced apart a predetermined length from the charger 14 on the downstream side of the charging device 14 along the rotational direction of the photosensitive drum 12 is an exposure position P 1, above the photosensitive drum 12, the exposure position P 1 Exposure apparatus 1 that emits exposure light toward
6 are provided. The exposure device 16 corresponds to the exposure unit of the present invention.

The exposure device 16 is a laser diode (LD)
18 are provided. The LD 18 is an LD driver 68 (FIG. 2)
The laser beam modulated according to the image to be formed is emitted in accordance with an image forming process (refer to details, which will be described later). A collimator lens 20 is arranged on the laser beam emission side of the LD 18, and the laser beam emitted from the LD 18 is converted into a parallel light beam by the collimator lens 20. A polygon mirror (rotating polygon mirror) 22 is disposed on the laser beam emission side of the collimator lens 20. The polygon mirror 22 is rotated at a high speed by a driving unit, and deflects the incident laser beam in a predetermined direction (main scanning direction).

On the laser beam emitting side of the polygon mirror 22, an fθ lens 2 for forming an image of the laser beam emitted from the polygon mirror 22 on the peripheral surface of the photosensitive drum 12
4. A cylindrical mirror 26 for correcting the tilt of the polygon mirror 22 is arranged in order. fθ lens 24
At the exposure position P 1 , the laser beam is transmitted to the peripheral surface of the photosensitive drum 12, and the irradiation position is set in the moving direction (process direction) of the peripheral surface of the photosensitive drum 12. Scanning (main scanning) is performed along a direction orthogonal to the scanning direction. The sub-scanning of the laser beam is performed by rotating the photosensitive drum 12.

The potential of the portion of the peripheral surface of the photosensitive drum 12 irradiated with the laser beam decreases in accordance with the irradiation light amount (for example, the potential decreases to about 100 V by the irradiation light amount for forming a black solid). Then, an electrostatic latent image is formed on the peripheral surface of the photosensitive drum 12. The laser beam is scanned along the process direction so that an image (electrostatic latent image) is formed at a predetermined recording density (for example, 600 dpi).

[0018] position spaced a predetermined length from the exposure position P 1 at the downstream side along the rotational direction of the photosensitive drum 12 exposing position P 1 is the developing position P 2, the outer peripheral side of the photosensitive drum 12 a position corresponding to the developing position P 2, the developing device 28 for developing the electrostatic latent image is provided. Developing device 28
Is a developing device that performs development using a one-component developer composed of a magnetic toner (for example, a magnetic toner containing about 48% by weight of a magnetic powder). The developer is stored in a bottom portion inside the housing 30.

In the housing 30, the photosensitive drum 12
And a predetermined distance (for example, about 0.3 mm)
Is arranged. The developing roller 32 includes a magnet roller 32A in which a plurality of magnetic poles having different polarities and magnetic forces are sequentially magnetized along the circumferential direction and fixedly supported by the housing 30, and a cylindrical roller rotatably disposed on the outer periphery of the magnet roller 32A. And a sleeve 32 </ b> B in a shape of a circle. Housing 3
The developer stored in the developing roller 32 is deposited on the rear side of the developing roller 32 (opposite to the photosensitive drum 12) by a blade-shaped developer supply member 34 that is driven to rotate, and is continuously formed on the surface of the sleeve 32B. Supplied.

The developer continuously supplied to the surface of the sleeve 32B is attracted to the sleeve 32B according to the magnetization pattern of the magnet roller 32A with the rotation of the sleeve 32B, conveyed, and released from the sleeve 32B. Further, a layer thickness regulating member 36 composed of a leaf spring 36A and a soft elastic member 36B attached to the tip of the leaf spring 36A is provided on the side of the developing roller 32. Soft elastic member 3
6B is urged by a leaf spring 36A so as to be in pressure contact with the sleeve 32B, and by preventing a part of the developer attached to the sleeve 32B from passing through, the sleeve 32B is pressed.
The layer thickness of the developer attached to B is made substantially constant.

A developing bias voltage is applied to a sleeve 32B of the developing roller 32 by a developing bias power supply 56 (see FIG. 2, details will be described later). With the rotation of the sleeve 32B of the developing roller 32, the developer conveyed to the position opposite to the photosensitive drum 12 while being attracted to the sleeve 32B receives the developing bias voltage applied to the developing roller 32 and the photosensitive drum. The electrostatic latent image formed on the peripheral surface of the photosensitive drum 12 adheres only to the exposed portion on the peripheral surface of the photosensitive drum 12 by the action of a developing electric field formed by the potential difference between the potential of the exposed portion and the potential of the exposed portion. You. As a result, the electrostatic latent image is developed, and a toner image is formed.

Further, a position separated a predetermined length downstream from the developing position P 2 of the developing position P 2 along the rotational direction of the photosensitive drum 12 is a transfer position P 3, the transfer position P
A transfer corotron 38 is arranged on the outer peripheral side of the photoconductor drum 12 corresponding to 3 . Further, below the developing device 28, a paper feed tray 40 capable of storing a large number of recording papers P is arranged. The paper feed tray 40 is detachable from the main body of the image forming apparatus 10, and the recording paper P stored in the paper feed tray 40 in the state where the paper feed tray 40 is mounted on the main body of the image forming apparatus 10 is used as the paper feed tray 40. The paper is pulled out of the paper feed tray 40 with the rotation of the paper feed roller 42 positioned above the paper feed roller 42, and is conveyed along a conveyance path indicated by imaginary lines in FIG. The recording paper P pulled out from the paper feed tray 40 is inserted between the transfer corotron 38 and the photosensitive drum 12, and
In the transfer position P 3, the toner image formed on the peripheral surface of the photosensitive drum 12 is transferred by the transfer corotron 38.

The transfer position P along the transport direction of the recording paper P
3 , a fixing device 44 having a heating roller 44A and a pressure roller 44B,
Are arranged in order. The recording paper P on which the toner image has been transferred is sent to the fixing device 44 by a conveying unit (not shown), where the toner image is fixed, and is discharged to the outside of the casing 10A via the discharge port 10B by the discharge roller 46. Is placed on the discharge tray 48 attached to the other side.

Further, on the downstream side of the transfer position P 3 along the rotational direction of the photosensitive drum 12, a cleaner 50 is provided with a blade 50A for removing residual toner on the peripheral surface of the photosensitive drum 12 Have been.

As shown in FIG. 2, the developing bias power supply 56
Is configured by connecting an AC power supply 56A and a DC power supply 56B in series, and generates a developing bias voltage in which an AC component is superimposed on a DC component. This developing bias voltage is
For example frequency 1.0kH Z, the peak-to-peak voltage of about 24
00V and the DC component can be about 200V. The developing bias power supply 56 is connected to the sleeve 32B of the developing roller 32 and the voltage divider 58. The developing bias voltage is applied to the sleeve 32B and supplied to the voltage divider 58.

The voltage divider 58 is connected to the phase adjuster 60, divides the supplied developing bias voltage to lower the voltage, and inputs the voltage to the phase adjuster 60 as a bias signal. The phase adjuster 60 is connected to the calculator 62, changes the phase of the input bias signal by an amount of phase change set from the outside, and inputs the bias signal with the changed phase to the calculator 62. This phase change amount can be changed and set from outside.

A video signal generator 64 is connected to the arithmetic unit 62. The video signal generator 64 receives an image to be formed on the recording paper P from a computer 66 connected to the image forming apparatus 10. Enter the data to represent.
The video signal generator 64 generates bitmap data representing an image to be formed on the recording paper P based on the data output from the computer 66, and based on the generated bitmap data, generates the image on the recording paper P. A video signal to be recorded in the computer is created and input to the arithmetic unit 62.

An arithmetic unit 62 drives the LD 18 based on the bias signal input from the phase adjuster 60 and the video signal input from the video signal generator 64.
Generate a D drive signal. Specifically, the LD drive signal is, for example, a light amount correction value for correcting the light amount of the laser beam emitted from the LD 18 according to the level of the bias signal input from the phase adjuster 60 in the main scanning direction. Are set in units of one line of the image along. The light amount correction value is set such that the light amount increases as the level of the bias signal decreases, and decreases as the level of the bias signal increases. Then, the level of the video signal that changes in units of one dot of the image is obtained by correcting the level of the video signal in units of one dot according to the light amount correction value.

The arithmetic unit 62 is connected to an LD driver 68, and the LD driver 68 is connected to the LD 18. The calculator 62 outputs the generated LD drive signal to the LD driver 68, and the LD driver 68 drives the LD 18 according to the LD drive signal input from the calculator 62. Thus, the exposure amount by the laser beam emitted from the LD 18 is adjusted according to the LD drive signal. Note that the voltage divider 58, the phase adjuster 60, and the calculator 62 correspond to the adjusting means (more specifically, the adjusting means according to claim 2) of the present invention.

Next, the operation of the present embodiment will be described. For example, in the case where a halftone image having a uniform and intermediate density on the entire surface is formed on the recording paper P, if the adjustment of the exposure amount according to the present invention is not performed, as shown in FIG. Since the light amount (exposure amount) of the laser beam emitted from the laser beam and irradiated on the peripheral surface of the photosensitive drum 12 is constant, the potential of the electrostatic latent image formed on the peripheral surface of the photosensitive drum 12 is also constant. Become.

On the other hand, in the developing bias voltage applied to the sleeve 32B of the developing roller 32, since the AC component is superimposed on the DC component, the magnitude of the voltage fluctuates at the same cycle as the AC component. As described above, since the potential of the electrostatic latent image is constant, the magnitude of the developing electric field which is the difference between the potential of the electrostatic latent image (specifically, the potential of the exposed portion) and the developing bias voltage is the same as the AC component. The density fluctuates periodically, and a periodic density fluctuation along the process direction is applied to a toner image formed by developing the electrostatic latent image. In particular, in a halftone image, this fluctuation in density is clearly recognized as banding.

As an example, the photosensitive drum 12 is rotated at a peripheral speed of 300 mm / sec, and a laser beam is applied to the photosensitive drum 12 so that an electrostatic latent image is formed at a recording density of 600 dpi along the process direction. it is scanned over the peripheral surface, if the frequency of the AC component of the developing bias power source 56 and a 1.0KH Z, banding occurs at a pitch of 0.3 mm (7 lines along the process direction) along the process direction.

On the other hand, in the image forming apparatus 10 according to the present embodiment, the bias signal obtained by dividing the developing bias voltage by the voltage divider 58 is applied to the phase adjuster 60.
Is input to the arithmetic unit 62 through the arithmetic unit 62. Based on the bias signal, the arithmetic unit 62 increases the amount of emitted light as the level of the bias signal decreases and decreases the amount of emitted light as the level of the bias signal increases. And LD1
The light amount of the laser beam emitted from 8 is adjusted. As a result, the light amount of the laser beam emitted from the LD 18 (the amount of exposure to the photosensitive drum 12) is increased or decreased in the same cycle as the developing bias voltage.

[0034] However, the predetermined position on the peripheral surface of the photosensitive drum 12, the timing when the electrostatic latent image is exposed in the exposure position P 1 is formed, developing a line of an electrostatic latent image at the developing position P 2 There is a time difference t between the timing and the timing, and the size of the time difference t varies among the image forming apparatuses due to the influence of the dimensions of the components constituting the image forming apparatus 10 and the tolerance of the mounting position. For this reason, in the present embodiment, in order to suppress the fluctuation of the density along the process direction, before forming an image on the recording paper P based on the data output from the computer 66 (for example, at the time of shipping), the following will be described. Perform adjustment work.

When the operator notifies the image forming apparatus 10 of the execution of the adjustment work, the image forming apparatus 10
To form a halftone image. That is, the video signal creator 64 fixedly stores image data representing the halftone image in advance, and when notified of the execution of the adjustment work, a video signal for forming a halftone image based on the image data. A signal is created and output to the computing unit 62. On the other hand, the bias signal output from the voltage divider 58 is
The phase is changed by the phase change amount set in advance by the phase adjuster 60 and is input to the calculator 62. Arithmetic unit 62
Is L based on the input video signal and bias signal.
A D drive signal is generated and output to the LD driver 68. As a result, the LD 18 emits a laser beam whose light amount increases and decreases in the same cycle as the developing bias voltage.

The laser beam emitted from the LD 18 is
Through the collimator lens 20, the polygon mirror 22, the fθ lens 24, and the cylindrical mirror 26, the exposure position P
In 1 , the peripheral surface of the photosensitive drum 12 charged in advance by the charger 14 is irradiated, and the peripheral surface is scanned and exposed. As shown in FIG. 3B, the exposure amount at this time changes periodically along the process direction, and the potential of the electrostatic latent image of the halftone image formed by this scanning exposure also changes. As shown in (), it changes periodically along the process direction. The electrostatic latent image formed on the circumferential surface of the photosensitive drum 12 is developed by the developing device 28 at the developing position P 2, the toner image formed by the development is at the transfer position P 3, the paper feed tray 40 Is transferred onto the recording paper P pulled out from the printer. The recording paper P to which the toner image has been transferred is fixed with the toner image by the fixing device 44, discharged out of the casing 10 </ b> A, and placed on the discharge tray 48.

The operator visually checks the halftone image formed on the recording paper P discharged onto the discharge tray 48,
Direction corresponding to the process direction (recording paper P discharge direction)
The presence or absence of density fluctuation (banding) along the line is tested. If the phase change amount set in the phase adjuster 60 is not an appropriate value corresponding to the time difference t, banding occurs in the halftone image formed on the recording paper P. As a result of the test, if it is determined that banding has not occurred in the formed halftone image, the adjustment work is terminated. However, if it is determined that banding has occurred in the halftone image, the operator determines the phase. Changing the phase change amount to the adjuster 60, forming a halftone image, and verifying the halftone image formed on the recording sheet P are repeated until it is determined that the banding has been eliminated. The phase change amount is adjusted so as to eliminate.

When the amount of phase change reaches an appropriate value corresponding to the time difference t, the portion of the electrostatic latent image having a lower potential is set in the developing device 2.
When the developing device 8 develops, the developing bias voltage also has a low value, and when the developing device 28 develops a high potential portion of the electrostatic latent image, the developing bias voltage also has a high value. Accordingly, since the developing electric field, which is the difference between the potential of the electrostatic latent image and the developing bias voltage, is constant, the density of the toner image is constant along the process direction as shown in FIG. Banding of the image formed on the sheet P is also eliminated.

After the above adjustment work is performed, the phase adjuster 60 changes the phase of the bias signal in accordance with the phase change amount adjusted by the adjustment work, and the arithmetic unit 62 adjusts the phase by the phase adjuster 60. Since the light amount of the laser beam emitted from the LD 18 is adjusted based on the changed bias signal, even if the image represented by the data output from the computer 66 is an image including a halftone area, Banding can be suppressed from occurring in the halftone area, and the computer 6
6, even if the image represented by the data output from the image does not include a halftone area, it is possible to suppress the periodic density fluctuation along the process direction from being added to the image. The image quality of the image formed by the device 10 can be improved.

In the above description, the exposure amount is adjusted by changing the light amount of the laser beam emitted from the LD 18. However, the present invention is not limited to this. The exposure amount may be adjusted by changing the time.

In the above description, the operator adjusts the phase change amount set in the phase adjuster 60 based on the density unevenness of the image formed on the recording paper P. However, the present invention is not limited to this. Instead, a density sensor for detecting the density of the image formed on the recording paper P or the toner image formed on the peripheral surface of the photosensitive drum 12 is provided, and a halftone image is formed in the same manner as described above. And automatically determining whether or not density unevenness has occurred in the image or the toner image in the process direction based on the density value detected by the density sensor, and automatically adjusts the phase change amount. You may do so.

In the above description, the image forming apparatus according to the present invention is based on data output from a computer.
A printer that forms an image represented by the data on recording paper has been described as an example.However, the present invention is not limited to this. For example, a copier that includes a scanner that reads an image of a document and that forms an image of the document on recording paper, Needless to say, the present invention can be applied to an image forming apparatus such as a facsimile apparatus having a function of reading an image of a document and a function of transmitting and receiving image data and forming an image represented by the received image data on a recording sheet.

[0043]

As described above, according to the first aspect of the present invention, the developing means is configured to apply a developing bias voltage in which an AC component is superimposed on a DC component and to apply the developing bias voltage on the image carrier. Exposure means scans and exposes the image carrier on the image carrier so that the influence of the periodic fluctuation of the developing bias voltage due to the AC component when developing the electrostatic latent image using the developer is cancelled. When developing with a developing bias voltage in which an alternating current component is superimposed on a direct current component, the density fluctuation caused by the alternating current component included in the developing bias voltage is suppressed because the exposure amount when forming is adjusted. It has an excellent effect of being able to.

According to a second aspect of the present invention, in the first aspect of the present invention, the amount of exposure by the exposing means is adjusted based on a signal obtained by dividing the developing bias voltage applied to the developing means and adjusting the phase. Therefore, in addition to the above effect, the effect that the exposure amount can be adjusted so that the exposure amount periodically changes in the same cycle as the AC component can be realized without incurring a complicated configuration. Have.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment.

FIG. 2 is a schematic block diagram illustrating a part related to adjustment of an exposure amount in the image forming apparatus illustrated in FIG.

FIG. 3A shows a case where the exposure amount is not adjusted.
(B) is a line showing the relationship between the position on the photoconductor along the process direction, the exposure amount, the electrostatic latent image potential, and the toner image (image) density when the exposure amount is adjusted. FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Image forming apparatus 12 Photoreceptor drum 16 Exposure apparatus 18 LD 28 Developing apparatus 56 Developing bias power supply 58 Voltage divider 60 Phase adjuster 62 Computing unit 68 LD driver

Claims (2)

    [Claims]
  1. An image carrier; a charging unit configured to charge the image carrier; and a light modulated in accordance with an image to be formed is scanned and exposed on the image carrier charged by the charging unit, and the image is scanned. Exposure means for forming an electrostatic latent image on the carrier, and a developer biasing the electrostatic latent image formed on the image carrier in a state where a developing bias voltage in which an AC component is superimposed on a DC component is applied. Developing means for developing using the developing means, wherein the exposing means scans and exposes the image carrier on the image carrier so as to cancel out the effect of the periodic fluctuation of the developing bias voltage due to the AC component when the developing means performs development. And an adjusting means for adjusting an exposure amount when the image forming apparatus is operated.
  2. 2. The method according to claim 1, wherein the adjusting unit adjusts an exposure amount by the exposing unit based on a signal obtained by dividing the developing bias voltage applied to the developing unit and adjusting a phase. The image forming apparatus according to claim 1.
JP9340986A 1997-12-11 1997-12-11 Image forming device Pending JPH11174751A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP9340986A JPH11174751A (en) 1997-12-11 1997-12-11 Image forming device

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP9340986A JPH11174751A (en) 1997-12-11 1997-12-11 Image forming device

Publications (1)

Publication Number Publication Date
JPH11174751A true JPH11174751A (en) 1999-07-02

Family

ID=18342152

Family Applications (1)

Application Number Title Priority Date Filing Date
JP9340986A Pending JPH11174751A (en) 1997-12-11 1997-12-11 Image forming device

Country Status (1)

Country Link
JP (1) JPH11174751A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6256465B1 (en) 1998-10-16 2001-07-03 Ricoh Company, Ltd. Image forming apparatus and image forming unit therefor

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6256465B1 (en) 1998-10-16 2001-07-03 Ricoh Company, Ltd. Image forming apparatus and image forming unit therefor

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