JP2003114553A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device that decreases a change in exposure potential caused by a decrease in initial potential and ensures stable exposure potential. SOLUTION: The image forming device has an electrification means (2) for electrifying the surface of a photoreceptor (1), an exposure means (3) for irradiating the electrified area of the photoreceptor with a specific quantity of light, thereby forming an electrostatic latent image on the photoreceptor, and a quantitative light control means (10) for controlling a quantity of light. In the image forming device, the quantitative light control means (10) is provided with a first quantitative light setting means and a second quantitative light setting means. The first quantitative light setting means sets, based upon information about the propagation characteristic of charges in the photoreceptor, a first quantity of exposure light that is used for the initial stage of the start of printing. The second quantitative light setting means sets a second quantity of exposure light that is used after the initial stage.

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 that forms an image using an electrophotographic process.

[0002]

2. Description of the Related Art In order to maintain stable image quality in an electrophotographic process for a long period of time, it is important how stable an electrostatic latent image can be formed on a photoconductor. The electrostatic latent image includes a charging potential (the surface potential (V0) of the photoconductor in a region uniformly charged by the charger) and an exposure potential (a potential of the photoconductor in a region exposed by the beam emitted from the exposure device ( VR)) is generally formed by.

Normally, the charging potential (V0) and the exposure potential (V
R), the developing potential (VB) is set appropriately to define the contrast potential, the developer is supplied to the photoconductor by the potential difference of the contrast potential, and a developed image of a predetermined density is formed on the photoconductor. It Here, the contrast potential when the developing step of the electrophotographic process is the reversal developing method is
Defined by | VB−VR |. In addition, the contrast potential when the developing process is the regular developing method is | V0-VB |
Defined by

[0004]

By the way, as the factors for changing the charging potential and the exposure potential in the image forming apparatus of this type, up to now, the environment (temperature, humidity) around the photoconductor has been considered.
Attention has been paid to fluctuations and changes in the film thickness of the photoreceptor over time, and various configurations and the like for ensuring potential fluctuations based on these factors have been proposed.

However, the inventors of the present invention have discovered that traps are latent inside the photosensitive layer in addition to the above-mentioned factors, and have found a countermeasure against them.

Therefore, it is an object of the present invention to provide an image forming apparatus capable of reducing the fluctuation of the exposure potential due to the initial potential lowering phenomenon described later and ensuring a stable exposure potential.

[0007]

The above-mentioned object is to charge an electrostatic latent image on the photoconductor by charging the photoconductor surface with a charging means and irradiating the charged photoconductor region with light having a predetermined amount of light. An image forming apparatus comprising an exposing unit for forming a light amount and a light amount controlling unit for controlling the light amount, wherein the light amount controlling unit is used at an initial stage of printing based on information about a propagation characteristic of charges in the photoconductor. This is achieved by including first light amount setting means for setting a first exposure light amount and second light amount setting means for setting a second exposure light amount used after the initial stage has passed.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Before the description of the embodiments of the present invention, the "initial potential drop phenomenon" will be described. As a phenomenon, when a few minutes have passed after starting the printing operation in the image forming apparatus, the exposure potential decreases in a range of several volts to about 30 volts. It is considered that this phenomenon occurs due to the following reasons.

The photosensitive member is composed of, for example, a base material made of a conductive drum or sheet, and a photosensitive layer provided on the base material and having a thickness of several microns to several tens of microns. In such a photoconductor, the area exposed by the emitted beam generates electric charges (here, described as positive charges), and in the case of a normal photoconductor, the positive charges move to the surface of the photoconductor and are charged. An electrostatic latent image is formed by neutralizing the electric charges uniformly applied to the surface of the photoconductor in the step (which will be described as negative electric charges) to lower the potential of the beam-exposed region.

However, when traps are latent inside the photosensitive layer, the above-mentioned movement of positive charges is hindered. It is considered that the trap itself is generated by impurities or distortion of molecular bond of the photosensitive material during the manufacturing process of the photosensitive member. When this trap exists inside the photosensitive layer, among the positive charges that move toward the surface of the photoconductor, a positive charge that cannot be reached to the surface of the photoconductor and is trapped in the middle of the trap is generated. Only positive charges that have slipped through without being captured contribute to the formation of an electrostatic latent image. Therefore, when printing is started from the state where no positive charge is trapped in the trap (empty state), the electric charge trapped in the trap is large in the beginning and the electric charge reaching the photoconductor surface is small. It tends to show a high value.

If printing is continued for a while (about several minutes) from the above state, the exposure potential tends to decrease in the range of several volts to about 30 volts. It is considered that such a decrease in the exposure potential is caused by the following reasons.

That is, in the electrophotographic process, a developed image (usually a toner image) formed on a photoconductor is transferred to a recording material such as paper, and then a charge eliminator (charge eliminator lamp or the like) is formed on the surface of the photoconductor. ) Is used to eliminate the electric potential remaining on the surface of the photoconductor. The charges generated in this static elimination process gradually exhaust the traps inside the photosensitive layer, which makes it easier for the positive charges to reach the surface of the photoconductor, and as a result, the exposure potential is lowered compared to the initial printing start state. Be done. Therefore, a constant exposure potential can be obtained when all the traps are filled.

On the other hand, when printing is stopped, electric charge leaks from the traps. Therefore, the longer the stop time, the higher the exposure potential when printing is restarted.

The potential fluctuation due to the initial potential drop phenomenon as described above occurs in a very short time when the print start operation and the stop operation of the image forming apparatus are triggered. It is difficult to deal with such as control.

Embodiments of the present invention will be described in detail below with reference to the drawings. (First Embodiment) A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a schematic configuration diagram of an image forming apparatus of the present invention, in which 1 is a photosensitive drum, 2 is a charger, 3 is an exposure device, 4 is a developing device, 5 is a recording material, 6 is a transfer device, and 7 is a transfer device. A discharge lamp, 8 is a cleaner, 9 is a fixing device, 10 is a light amount control device, 11 is a timer, and 12 is a surface potential sensor. The photosensitive drum 1 is supported so as to rotate at a constant speed in the direction of the arrow shown. The charger 2 is arranged so as to face the surface of the photoconductor drum 1.
The surface of the photoconductor drum 1 passing so as to face is uniformly charged. The exposure device 3 that exposes the uniformly charged surface of the photosensitive drum 1 irradiates a beam in accordance with a print information signal from an information processing device (not shown) to form an electrostatic latent image on the surface of the photosensitive drum 1. Form.

The developing device 4 is arranged so as to face the surface of the photosensitive drum 1 on which the electrostatic latent image is formed. The developing device 4 has a developing function of adhering fine powder toner to the surface of the photosensitive drum 1 by the electrostatic force of the electrostatic latent image to form a toner image.

The transfer device 6 applies a charge having a polarity opposite to that of the toner image to the back surface of the recording material 5 to move (transfer) the toner image formed on the photosensitive drum 1 to the surface of the recording material 5. Generates electrostatic force. Then, the recording material 5 on which the toner image is transferred is sent to the fixing device 9, and the toner image is fixed on the recording material 5 by the heating and pressurizing action there.

On the other hand, the entire surface of the photosensitive drum 1 which has passed through the transfer device 6 is exposed by the charge eliminating lamp 7, the remaining electrostatic latent image is erased, and the cleaner 8 is used to clean the surface. Prepared for the print cycle.

FIG. 2 is an explanatory diagram showing the relationship between the exposure light amount and the exposure potential, and FIG. 3 is an explanatory diagram showing the transition of the exposure potential when printing is continued in the state where the exposure light amount is constant, and arrow a in FIG. The printing continuation time required until the initial potential decrease amount becomes constant, and the arrow b indicates the decrease amount of the exposure potential due to the initial potential decrease. Further, in FIG. 3, Tc is a print duration time until the exposure potential is reduced by half the exposure potential reduction amount (b / 2).

FIG. 4 is an explanatory diagram showing the relationship between the stop time of the image forming apparatus and the initial potential decrease amount, and arrow c indicates the print stop time until the initial potential decrease amount becomes constant.

FIG. 5 is an explanatory view showing an example of a table used for the exposure correction, and the stop time is divided into several regions (in the present embodiment, the stop is performed in accordance with the relationship between the stop time of the image forming apparatus of FIG. 4 and the initial potential decrease amount). (The time is divided into four areas), and the average value of the initial potential decrease amount (Va) for each area of the stop time
The amount of change in the exposure light amount in which the potential changes by half the amount (Va / 2) is obtained from the relationship between the exposure light amount and the exposure potential in FIG. 2 and tabulated as the relationship between the stop time and the correction amount of the exposure light amount. .

Next, the procedure for correcting the exposure light amount will be described with reference to FIG. Prior to the start of printing, when the power source of the image forming apparatus is turned on, a patch of the exposure potential is created on the photoconductor, the exposure potential is measured by the potential sensor 12, and the exposure light amount is set up so as to reach the target potential. Next, the timer 11 measures the time from when the setup is completed to when printing is started.

After the printing is started, the duration of the printing is measured by the timer 11, and when a certain time Tc has elapsed,
According to the table shown in FIG. 5, the exposure light amount is reduced by the light amount correction amount according to the stop time measured before printing. After that, the exposure light amount is not changed until printing is stopped.

After the printing is stopped, the timer 11 measures the time until the next printing is restarted. Then, before the next printing is started and before the actual exposure is performed, according to the table shown in FIG. 5, the light amount correction amount corresponding to the stop time from the time when the previous printing operation is stopped until the printing is restarted is performed. Only increase the exposure light amount. After that, the correction of the exposure light amount is repeated in the same procedure each time printing and stopping are repeated.

FIG. 7 is an explanatory diagram showing the transition of the exposure potential when the exposure light amount is corrected by the procedure described above, and the dotted line shows the transition of the exposure potential when the exposure light amount is not corrected, and the arrow d indicates the fluctuation range of the exposure potential when the exposure light amount is not corrected, the solid line indicates the transition of the exposure potential when the exposure light amount is corrected, and the arrow e indicates the exposure when the exposure light amount is corrected. The fluctuation range of the potential is shown.

As shown in FIG. 7, by correcting the exposure light amount according to the present invention, even when printing and stopping are repeated, the fluctuation range of the exposure potential due to the initial potential lowering phenomenon is determined by the exposure light amount. It is possible to reduce the amount to about half as compared with the case where no correction is performed. (Second Embodiment) The second embodiment proposes a configuration in which a temperature sensor for detecting the surface temperature of the photoconductor is added to the image forming apparatus of the first embodiment.

When printing is performed with this configuration, a patch of the exposure potential is created on the photoconductor when the power source of the image forming apparatus is turned on, and the exposure potential is measured by the potential sensor 12 before the printing is started. The exposure light amount is set up so that the exposure potential becomes At this time, the surface temperature of the photoconductor is also measured by the temperature sensor, and the result is stored in the memory element provided in the controller or the like.

During printing, temperature changes are constantly detected by a temperature sensor, and when the surface temperature of the photoconductor is decreased by a preset temperature change amount, the exposure light amount is increased by a preset exposure amount. On the contrary, when the surface temperature of the photosensitive member is increased by a preset temperature change amount, the exposure light amount is decreased by the preset exposure amount when the temperature rises.

At the same time, like the first embodiment, when a certain time has elapsed from the start of printing, the exposure light amount is reduced based on the table of the stop time and the exposure correction amount, and reprinting is performed after the printing is stopped. When starting, the exposure light amount is increased based on the table of the stop time and the exposure correction amount. In addition, by observing when printing is stopped, a patch of the exposure potential is regularly formed on the photoconductor, the exposure potential is measured by the potential sensor 12, and the exposure light amount is adjusted so as to reach the target potential. Set up.

As described above, by periodically measuring the exposure potential with the potential sensor and setting up the amount of exposure light, the humidity of the atmosphere changes slowly over a relatively long time and the film thickness of the photoreceptor over time. Changes in the exposure potential due to changes can be absorbed, and by detecting the surface temperature of the photoconductor during printing and correcting the exposure light amount, fluctuations due to sensitivity changes with the exposure amount due to changes in the photoconductor temperature that change in a relatively short time. Of the initial potential drop phenomenon that occurs when printing is started or stopped by counting the time from the start of printing and the stop time and performing the correction of the exposure amount as described in the first embodiment. Since the fluctuation of the exposure potential can be absorbed, it is possible to correct all possible factors of the fluctuation of the exposure potential, and stabilize the exposure potential of the photoconductor with high accuracy. Rukoto is possible.

FIG. 8 is an explanatory diagram showing the transition of the exposure potential when continuous printing is performed in the configuration of the second embodiment.
f is the time when the photoconductor potential is measured and the exposure potential is set up, and g and h are the times when the change in the photoconductor surface temperature is detected and the exposure light amount is changed. Further, i, j, and k indicate the time points at which the exposure light amount is reduced after a certain time has elapsed from the start of printing. During the printing of 3,000 pages, the fluctuation of the exposure potential could be suppressed within the range of 16V over the entire width. (Third Embodiment) Next, a third embodiment of the present invention will be described with reference to FIGS. Here, the third embodiment is different from the above-described first and second embodiments in that it is an image forming apparatus that forms two color toner images on the photosensitive drum 1, and therefore FIG. The developing device 13 is added as shown in FIG. Since the other configurations are the same as those of the first or second embodiment, the same reference numerals are given and the description thereof is omitted.

In the two-color image forming apparatus shown in FIG. 9, when the photosensitive drum 1 (which uses a negatively charged OPC (organic photoconductor) as the photosensitive member) starts to rotate in the direction of the arrow, the charger The surface of the photoconductor drum 1 facing 2 is uniformly charged by the charger 2 and is in a state of holding a high potential corresponding to V0 in FIG.

The photoconductor region charged to the charging potential (V0) is exposed by the beam emitted from the exposure device 3 to record an electrostatic latent image. In this case, the electrostatic latent image includes the fringe suppression potential (VF1, VF2) and the intermediate potential in addition to the charging potential (V0) described above.
(VM) and exposure potential (VR) are combined. Note that VB1 and VB2 in FIG. 10 are developing biases applied to the developing roller of each developing device (details will be described later).

When the electrostatic latent image reaches the position facing the first developing device 13, the developing bias (VB1) applied to the developing roller 13a causes the charging potential (V
(0), which acts on the electrostatic latent image portion, and the electric field action between the charging potential (V0) and the developing bias (VB1) causes a so-called well-known normal development phenomenon, and the electrostatic latent image of the charging potential (V0). Toner having a polarity opposite to that of the photoconductor (positively charged toner in this example) is attached to the portion, and a first toner image of, for example, red color toner is formed on the photoconductor drum 1.

Subsequently, when the photoconductor region holding the electrostatic latent image and the first toner image reaches a position facing the second developing device 4, the developing bias voltage (VB2) applied to the developing roller 4a. ) Acts on the electrostatic latent image portion including the exposure potential (VR) in the electrostatic latent image, and due to the electric field action between the exposure potential (VR) and the developing bias (VB2), a so-called well-known reversal development phenomenon. The toner having the same polarity as the photoconductor (negatively charged toner in this example) is attached to the electrostatic latent image portion of the exposure potential (VR), and the second toner such as black toner is formed on the photoconductor drum 1. An image is formed.

Since the first toner image and the second toner image formed on the photosensitive drum 1 are formed by the toners having different charging polarities, the first toner image and the second toner image are transferred before the transfer to the recording material 5. The photoconductor region holding the second toner image is charged by the pre-transfer charger 14, and the first toner image and the second toner image are charged.
For example, the polarity of the toner image is made negative.

Each toner image having the same polarity is transferred to the transfer device 6.
When it reaches a position opposite to, due to the action of the transfer device 8 which applies a charge having a polarity opposite to that of the toner from behind the recording material 5,
Transferred from the photosensitive drum 1 to the recording material 5.

The photoconductor drum 1 after passing through the transfer unit 6 is destaticized by the destaticizing lamp 7, and then the photoconductor drum 1 is discharged.
The untransferred toner remaining on the surface is removed from the surface of the photosensitive drum 1 by the cleaner 8. Two-color image recording is continuously performed by repeating the above process.

On the other hand, the recording material 5 holding the first toner image and the second toner image is conveyed by the heat roller fixing device 9 consisting of a heating roller and a pressure roller, and at the same time, the fixing device 9
The toner forming the first toner image and the second toner image is fixed on the recording material 5 by the heating and pressurizing action.

In the above structure, the fringe suppression potentials (VF1, VF2) are potentials that contribute to prevent fringe development that occurs due to abrupt changes in the potential, and the fringe inhibition potentials (charge potential V0 and exposure It is formed in the range of about 400 μm in the peripheral portion of the potential VR). The value of each potential forming the electrostatic latent image is an example, but the charging potential (V
0) is -800V, fringe suppression potential (VF1) is -450V
V, intermediate potential (VM) is -400V, fringe suppression potential (VF
2) is -350V, and the exposure potential (VR) is about -50V. The developing bias (VB1) is about -500V, and the developing bias (VB2) is about -300V.

Here, the cause of occurrence of "fringe development",
The principle of the fringe suppression potential (VF1, VF2) will be described with reference to FIGS. 11 and 12.

FIG. 11A shows the surface potential of the photoconductor when the fringe suppression potentials (VF1, VF2) are not formed in the electrostatic latent image, and FIG. 11B shows the photoconductor surface potential shown in FIG. 11A. It is an electric field distribution diagram corresponding to a body surface potential.

In FIG. 11B, 0 ₁ is the 0 point of the electric field when the first developing device 13 is the reference, and 0 ₂ is the 0 point of the electric field when the second developing device 4 is the reference. Shows.
At the edges of the charging potential (V0) and the exposure potential (VR), it is caused by the rapid potential change between V0 and the intermediate potential (VM) and the rapid potential change between VM and VR. A reverse electric field is generated.

When the electrostatic latent image formed on the photosensitive drum 1 passes through the first developing device 13 containing the positively charged toner, the area (A1, A) where the electric field on the + side of 0 ₁ exists.
2, A3) is developed with positively charged toner. Further, when the electrostatic latent image passes through the second developing device 4 in which the negatively charged toner is stored, the area (B1, B1) where the electric field on the negative side of 0 ₂ exists.
2, B3) is developed with negatively charged toner.

Here, of the areas A1, A2, A3, B1, B2, B3, the areas A2, A3, B2, B3 are areas where a toner image does not adhere and must be in a blank sheet state. If areas B2 and B3 are present on both sides of the area A1 as in b), the periphery of the black image is represented as an image with a red border. Further, if the areas A2 and A3 are present on both sides of the area B1, the periphery of the red image is represented as an image with a black border. This phenomenon is called fringe.

FIG. 12A shows the surface potential of the photoconductor when fringe suppression potentials (VF1, VF2) are formed in the electrostatic latent image.
FIG. 12B is an electric field distribution diagram corresponding to the photoconductor surface potential shown in FIG. However, this example shows a case where fringe suppression is performed on the regions A3 and B3 shown in FIG. 11B.

As shown in FIG. 12, when the fringe suppression potentials (VF1, VF2) are formed in the electrostatic latent image, the fringes are prevented from being generated in the areas A3 and B3, and the high quality 2 without background stain is obtained. Color printing is realized. Here, in order to sufficiently reduce the reverse electric field and prevent fringe development, the fringe suppression potential is set.
There is an optimum value for (VF1, VF2), and the allowable fluctuation range is 30V.
It becomes ~ 50V.

In the above two-color image forming apparatus, the potentials formed by the exposure of the outgoing beam are VF1, VM, VF
Since there are 2 and 4 VRs, it is required to keep 4 potentials stable. Hereinafter, a configuration for stabilizing these four potentials will be described.

As in the first embodiment, when the power of the image forming apparatus is turned on prior to the start of printing, four potentials VF1, V are applied to the photosensitive member.
M, VF2, and VR patches are created, each potential is measured by the potential sensor 12 shown in FIG. 9, and the exposure light amount for each of the four potentials is set up so as to be a target potential.

When a certain time has elapsed from the start of printing,
Based on the table of the stop time and the exposure correction amount, the respective exposure light amounts forming the four potentials are reduced, and when reprinting is started from the printing stop, the four potentials are set based on the table of the stop time and the exposure correction amount. The amount of each exposure light that forms a potential is increased. Here, four tables of the stop time and the exposure correction amount may be provided independently for each exposure light amount forming the four potentials, and when there is no great difference in the initial potential lowering characteristics of the four exposure potentials. , The same table may be used.

As described above, by counting the time from the start of printing and the stop time and correcting the exposure amount,
It is possible to absorb the fluctuation of the exposure potential due to the phenomenon of initial potential reduction caused by the start and stop of printing, stabilize the exposure potential of the photoconductor, and prevent the occurrence of fringe development.

In this example, the electrostatic latent image area A3
And fringe suppression potential (VF1, VF2) in the area corresponding to area B3
However, the fringe suppression potential may also be formed at the portions corresponding to the regions A2 and B2. (Fourth Embodiment) The fourth embodiment proposes a configuration in which a temperature sensor for detecting the surface temperature of the photoconductor is added to the two-color image forming apparatus of the third embodiment.

In the case of printing with this configuration, before the printing is started, when the power of the image forming apparatus is turned on, 4 is printed on the photoconductor.
A patch of one electric potential VF1, VM, VF2, VR is created, the electric potential is measured by the electric potential sensor 12, and the exposure light amount is set up for each of the four electric potentials so as to be a target electric potential.

At this time, the surface temperature of the photosensitive member is measured by the temperature sensor 15, and the result is stored in the storage element provided in the controller or the like.

During printing, the temperature sensor 15 constantly detects a temperature change, and when the surface temperature of the photoconductor is lowered by a preset temperature change amount, the respective exposure light amounts forming four potentials are set in advance. The exposure amount is increased by the set exposure amount, and conversely, the exposure light amount that forms four potentials when the surface temperature of the photoconductor is increased by the preset temperature change amount is set in advance. The amount of exposure should be reduced by the same amount.

At the same time, when a certain time has elapsed from the start of printing, the respective exposure light amounts forming four potentials are reduced based on the table of the stop time and the exposure correction amount,
When reprinting is started from the printing stop, each exposure light amount forming four potentials is increased based on the table of the stop time and the exposure correction amount. In addition, by observing when printing is stopped, patches of four potentials are regularly formed on the photoconductor, and the four potentials are measured by the potential sensor 12 so that the target potentials are obtained. The amount of exposure light is set up for each of the two potentials.

As described above, it is possible to periodically use the potential sensor 4
By measuring one potential and setting up the amount of exposure light for each of the four potentials, it is possible to absorb changes in the exposure potential due to changes in the humidity of the atmosphere that change slowly over a relatively long period of time and changes in the photoconductor film thickness over time. Further, by detecting the surface temperature of the photoconductor during printing and correcting the exposure light amount, it is possible to absorb the fluctuation due to the sensitivity change with respect to the exposure amount due to the temperature change of the photoconductor that changes in a relatively short time. By correcting the exposure amount by counting the time and stop time, it is possible to absorb the fluctuations of four potentials due to the initial potential drop phenomenon that occurs when printing starts and stops, so the potential of the photoconductor is stabilized with high accuracy. And the occurrence of fringe development can be prevented.

[0058]

As described above, according to the present invention, it is possible to provide an image forming apparatus capable of reducing the fluctuation of the exposure potential due to the phenomenon of initial potential reduction and ensuring a stable exposure potential. You can

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an image forming apparatus of the present invention.

FIG. 2 is an explanatory diagram showing a relationship between an exposure light amount and an exposure potential.

FIG. 3 is an explanatory diagram showing a transition of an exposure potential when printing is continued with a constant exposure light amount.

FIG. 4 is an explanatory diagram showing a relationship between a stop time of the image forming apparatus and an initial potential decrease amount.

FIG. 5 is an explanatory diagram showing an example of a table used for light amount correction.

FIG. 6 is a flowchart showing an example of a procedure for correcting the exposure light amount.

FIG. 7 is an explanatory diagram showing changes in the exposure potential when the amount of exposure light is corrected.

FIG. 8 is an explanatory diagram showing changes in the exposure potential in the second embodiment of the present invention.

FIG. 9 is a schematic configuration diagram of a two-color image forming apparatus to which the present invention has been applied.

FIG. 10 is a schematic diagram showing the relationship between the electrostatic latent image and the developing bias of the two-color image forming apparatus.

FIG. 11 is a schematic diagram for explaining the principle of fringe development.

FIG. 12 is a schematic diagram for explaining the action of the fringe suppression potential.

[Explanation of symbols]

1 photoconductor drum 2 charger 3 exposure equipment 4 Developing device 5 recording materials 6 transfer device 7 Static elimination lamp 8 cleaner 9 Fixing device 10 Light control device 11 timer 12 Potential sensor

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Keisuke Kubota             Hitachiko, 1060 Takeda, Hitachinaka City, Ibaraki Prefecture             Machine Co., Ltd. (72) Inventor Katsuhiro Akinaga             Hitachiko, 1060 Takeda, Hitachinaka City, Ibaraki Prefecture             Machine Co., Ltd. (72) Inventor Shinichi Akazu             1060 Takeda Stock Association, Hitachinaka City, Ibaraki Prefecture             Hitachi Koki Information Technology             -In F-term (reference) 2H027 DA02 DA07 DA40 DE07 EA02                       EC06 EC11 EC14 EC17 EC20                 2H076 DA06 DA17 DA22 DA37

Claims (6)

[Claims] 1. A charging means for charging the surface of a photoconductor, an exposing means for irradiating the charged photoconductor region with light having a predetermined light quantity to form an electrostatic latent image on the photoconductor, and the light quantity An image forming apparatus comprising: a light amount control unit for controlling, wherein the light amount control unit sets a first exposure light amount to be used in an initial stage of printing start, based on information about a charge propagation characteristic in the photoconductor. An image forming apparatus comprising: a first light amount setting unit; and a second light amount setting unit that sets a second exposure light amount used after the initial stage has passed. 2. A charging means for charging the surface of the photoconductor, an exposing means for irradiating the charged photoconductor region with light having a predetermined light quantity to form an electrostatic latent image on the photoconductor, and the light quantity. An image forming apparatus including a light amount control unit for controlling, wherein the light amount control unit is used in an initial stage of printing start based on information about a charge propagation characteristic caused by traps latent in the photoconductor. A first light amount setting means for setting an exposure light amount, and a second light amount setting means used after the initial stage has passed
And a second light amount setting means for setting the exposure light amount of the image forming apparatus. 3. A charging means for charging the surface of the photoconductor, an exposing means for irradiating the charged photoconductor region with light having a predetermined light quantity to form an electrostatic latent image on the photoconductor, and the light quantity. An image forming apparatus including a light amount control unit for controlling, wherein the light amount control unit has data for obtaining a correction amount of the light amount based on a period (stop time) during which a printing operation is stopped, During the period from the start to the elapse of a predetermined time, the light amount is increased by a correction amount corresponding to the stop time, and after the elapse of the predetermined time, the light amount is returned to the light amount before the increase. An image forming apparatus comprising means. 4. A charging means for charging the surface of a photoconductor, and a static charge containing an electrification potential, an intermediate potential, an exposure potential and a fringe suppression potential by irradiating the charged photoconductor region with light having a predetermined amount of light. An image forming apparatus comprising: an exposure unit that forms a latent electric image; and a light amount control unit that controls the light amount, wherein the light amount control unit starts printing based on information about charge propagation characteristics in the photoconductor. An image forming method comprising: a first light amount setting means for setting a first exposure light amount used in an initial stage; and a second light amount setting means for setting a second exposure light amount to be used after the initial stage has passed. apparatus. 5. A charging means for charging the surface of a photoconductor, and a static charge containing a charging potential, an intermediate potential, an exposure potential and a fringe inhibition potential by irradiating the charged photoconductor region with light having a predetermined light amount. An image forming apparatus comprising: an exposure unit that forms a latent electric image; and a light amount control unit that controls the light amount, wherein the light amount control unit relates to a propagation characteristic of charges resulting from traps latent in the photoconductor. First light amount setting means for setting a first exposure light amount used in the initial stage of printing start based on the information, and second light amount setting means used after the initial stage has passed.
And a second light amount setting means for setting the exposure light amount of the image forming apparatus. 6. A charging means for charging the surface of the photoconductor and a static charge containing a charging potential, an intermediate potential, an exposure potential and a fringe inhibiting potential, by irradiating the charged photoconductor region with light having a predetermined light amount. An image forming apparatus comprising: an exposure unit that forms a latent electric image; and a light amount control unit that controls the light amount, wherein the light amount control unit is based on a period during which a printing operation is stopped (stop time). Having the data for obtaining the correction amount of the light amount, during the period from the start of printing until the predetermined time elapses, the light amount is increased by the correction amount corresponding to the stop time, and after the predetermined time elapses. The image forming apparatus includes means for returning the light amount to the light amount before increasing.