JP2002082501A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce burdens of man-hours in the case of controlling the density of an image on a photoreceptor. SOLUTION: All data are managed by an arithmetic control means 10, and individual related means are controlled by the means 10. Information on the image density on the photoreceptor detected by a density detecting means 12 is accumulated in a storage means 11. Further, reference and allowable limit image density information to be compared with the image density information is previously accumulated, and if necessary, individual pieces of image density information are compared and calculated by the arithmetic control means 10, and then image density adjusting information is transmitted to a power supply means 1. Individual power supply characteristic values of an electrifying means 2 and/or a developing means 5 are adjusted and controlled by the power supply means 1 according to the adjustment information to automatically obtain the desired density of the image on the photoreceptor. The image density information on the photoreceptor is compared with the reference image density information and calculated, and the result is transmitted to an exposure means 4. Then the exposure energy is controlled, to automatically obtain the desired density of the image on the photoreceptor.

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 for forming an image by an electrophotographic system, such as a facsimile machine, a copying machine, and a printer.

[0002]

2. Description of the Related Art Conventional image forming apparatuses of this type include:
There is an image forming apparatus described in Japanese Patent Application Laid-Open No. Hei 8-21729, in which a developer transport amount detecting means for detecting an amount of developer transported to a developing area and a signal from the developer transport amount detecting means are stored. There is described a configuration including a data storage unit for performing the processing, and a developing bias control unit for controlling an output image by changing a developing bias based on data in the data storage unit.

The image forming apparatus described in Japanese Patent Application Laid-Open No. H11-149191 has a density detecting means for detecting an image density on a transfer sheet onto which a toner image has been transferred, and a charging device based on the detected density data. And an image forming control means for controlling at least one of the exposure, development and transfer means to vary the amount of toner to obtain a predetermined image density.

[0004]

An electrophotographic system used in an image forming apparatus such as a facsimile apparatus at present is
The surface of the photoreceptor is charged by a charging unit, and the image information is formed as an electrostatic latent image on the charged surface of the photoreceptor by exposure energy from an exposure unit or a latent image forming unit. Further, image formation is performed by a process in which the electrostatic latent image is formed into a toner image by a developing unit and transferred to transfer paper by a transfer unit.

In such a process, the final amount of toner on the transfer paper determines the formed image density, which depends on the amount of toner on the photoreceptor to be transferred. That is, the image density of the toner image visualized on the photoconductor finally determines the image density on the transfer paper.

The image density in an image forming apparatus used in a current facsimile apparatus or the like is determined by separately measuring the image density on a transfer sheet discharged from the image forming apparatus by an image density measuring apparatus. In the manufacturing process, a method is adopted in which parameters for performing processes such as charging, exposure, development, and transfer are adjusted to match a predetermined density value.

In the case where the user uses the image forming apparatus, when the image density has deviated from the reference density due to the exchange of the photoconductor or the deterioration of the photoconductor, the above parameters are manually set by the user or a serviceman. Adjustments are made to maintain image density.

However, such a method has a very large human burden of visually checking the image density recorded on the output transfer paper one by one and adjusting the parameters of the image forming apparatus. To get the value,
Due to variations in the photoreceptor sensitivity, it is necessary to repeatedly adjust the photoreceptor every time the photoreceptor is replaced or whenever the photoreceptor deteriorates, resulting in a large time loss.

SUMMARY OF THE INVENTION The present invention is directed to solving the problems of the prior art, and provides an image forming apparatus in which the burden on human and time is reduced when controlling the image density on a photosensitive member. The purpose is to:

[0010]

In order to achieve the above object, an image forming apparatus according to the present invention comprises a photosensitive member, a charging means for charging the surface of the photosensitive member, and a photosensitive member having a surface exposed to light. An exposure unit that forms an electrostatic latent image, a developing unit that supplies toner to the electrostatic latent image to form a toner image, and a transfer unit that transfers a toner image visualized on a photoconductor to transfer paper. In the image forming apparatus, density detecting means for detecting a visualized image density on the photoconductor, and image density information serving as a reference and image density information serving as an allowable limit for the image density on the photoconductor are stored. Storage means, an operation control means for comparing the image density information detected by the density detection means with the image density information stored in the storage means, and an image forming condition based on the calculated image density difference. Change the image Characterized in that an image forming control means for controlling a degree.

Further, the control of the image density on the photoreceptor is performed by
Automatically executed when mounted on the device by replacement with a new photoconductor, arbitrarily executed when the user deems it necessary, executed at any fixed period, and furthermore, photoconductor As a result of executing the above control of the image density, when an image density lower than the permissible image density information stored in the storage means is detected, the life of the photosensitive member is indicated. .

According to the above-mentioned configuration, by controlling the image density based on the result of the density detecting means for detecting the image density on the photosensitive member, human and time burdens can be reduced and stable image density can be obtained. Control can be performed.

Further, when the above-described control processing is replaced with a new photosensitive member, the image density is controlled by executing the judgment by the user or at an arbitrary fixed cycle, and further, the control is performed after the image density is controlled. If the result is below the stored allowable image density information, the life of the photoconductor is determined and displayed, so that a stable image density can always be obtained.

[0014]

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

FIG. 1 is a block diagram schematically illustrating an image forming apparatus according to an embodiment of the present invention, and FIG. 2 is a schematic configuration diagram.

Here, a general electrophotographic process will be briefly described. The charging means 2 receiving the specified power supply from the power supply means 1 sets the photosensitive member 3 at a specified potential (for example, -750).
V). The exposure unit 4 irradiates the photoreceptor 3 charged to a prescribed potential with exposure energy to increase the surface potential of the photoreceptor 3 (for example, −150).
V) to form a latent image of the final image. The developing unit 5 generally has a large roller shape, and the potential (for example, −400 V..., This is referred to as a developing bias potential) supplied from the power supply unit 1 is applied to an amount corresponding to the potential (negative by a separate unit (not shown)). The (charged) toner 6 is electrostatically held on the surface.

The developing means 5 in this state (= developing roller)
When the toner comes into contact with or comes close to the photoconductor 3 on which the latent image of the final image has been formed, the toner 6 develops due to the potential difference.
(= Developing roller) The surface of the photoconductor 3 is changed from the surface to a latent image portion (for example, -150 V) of the photoconductor 3, and the toner image is visualized. The transfer unit 7 is supplied with a specified current (for example, 5 μA at a positive potential) from the power supply unit 1 and is disposed at a position facing the photoconductor 3 with the transfer paper 8 interposed therebetween.
When the toner 6 that has transitioned to the latent image portion (for example, −150 V) of the final image approaches the transfer unit 7 due to the rotation of the photoconductor 3, the toner 6 will transition to the transfer unit 7 due to the potential difference as described above. However, the toner 6 is actually transferred to the transfer paper 8 because the transfer paper 8 exists during the time.

Next, the present embodiment will be outlined with reference to FIG. The arithmetic control unit 10 shown in FIG. 1 controls all data in the present embodiment and controls each related unit. The storage unit 11 mainly stores information on the image density on the photoconductor 3 detected by the density detection unit 12, and also stores reference image density information and an allowable limit image for comparison with the image density information. The density information is stored in advance (this method and means are not particularly limited), and each of the image density information is compared and calculated by the arithmetic control means 10 as necessary. As a result, the adjustment information of the image density is obtained. The power is transmitted to the power supply unit 1.

The power supply unit 1 adjusts and controls each power supply characteristic value for either the charging unit 2 or the developing unit 5 or a plurality of units based on the adjustment information, so that a desired photosensitive member 3 Can be automatically obtained.

The arithmetic and control means 10 controls the photosensitive member 3
The above image density information and reference image density information are compared and calculated,
The result is transmitted to the exposure unit 4 to adjust and control the amount of exposure energy, so that a desired image density on the photoconductor 3 can be automatically obtained.

This will be described in more detail with reference to FIGS. The density detecting unit 12 detects the image density on the photoconductor 3 and stores the information in the storage unit 11. Storage means 11
The reference image density information is stored in advance, and the arithmetic control unit 10 compares the image density information on the photoreceptor 3 with the reference image density information or the allowable limit image density information.
The power supply unit 1 and the exposure unit 4 are controlled to eliminate the difference (= density difference).

That is, since the power supply unit 1 controls the power supply to the charging unit 2, the developing unit 5 and the transfer unit 7, the charging unit 2 includes an arithmetic control unit 10
As a result of the comparison operation between the image density information on the photosensitive member 3 and the reference image density information or the allowable limit image density information, the difference (= density difference) is removed as shown in FIG. By controlling the potential through the power supply unit 1, a predetermined image density can be obtained.

Similarly, in the developing means 5, the difference (= density) is obtained from the result of the comparison operation between the image density information on the photosensitive member 3 by the arithmetic control means 10 and the reference image density information or the allowable limit image density information. As shown in FIG. 4, in order to eliminate the difference, the developing bias potential is controlled through the power supply means 1 to obtain a predetermined image density.

Further, in the exposing means 4, as a result of a comparison operation between the image density information on the photoreceptor 3 by the arithmetic control means 10 and the reference image density information or the allowable limit image density information, the difference (= density difference) is obtained. As shown in FIG. 5, a predetermined image density can be obtained by controlling the amount of exposure energy to eliminate the energy.

Next, in the image forming apparatus according to the present embodiment, when the photoconductor 3 is newly mounted on the apparatus (as long as it is a means for detecting that the photoconductor 3 is mounted, the configuration is not particularly limited here. No) The image density control on the photoconductor 3 is automatically executed by the arithmetic and control unit 10 so that the image density can be automatically corrected including the variation in the sensitivity of the photoconductor 3 and the image density can be kept constant. .

At any point in time when the user or serviceman determines that image density adjustment is necessary, an instruction to execute image density control is given to the arithmetic and control unit 10 (by pressing a switch provided on the operation panel of the apparatus). The method is not limited, for example), so that the image density control on the photoreceptor 3 can be executed as needed to keep the image density constant.

Finally, the execution timing for executing the image density control on the photoreceptor 3 can be arbitrarily set for the arithmetic and control unit 10 so that it can be set at an arbitrary cycle (for example, once every morning and once a month). The image density control on the photoconductor 3 can be executed to keep the image density constant.

Here, as the control for adjusting the image density, for example, by detecting or executing the replacement of the photosensitive member 3, for example,
A test pattern is formed on the photoconductor 3, or at the start of the next image forming process, the density is detected from the toner image visualized on the photoconductor 3, and the process is executed.

Further, in any case, after the image density control on the photosensitive member 3 is executed, a comparison operation between the image density information on the photosensitive member 3 and the allowable limit image density information is performed. When the image density is lower than the image density, the life of the photoconductor is automatically determined by outputting the result of determination of the life of the photoconductor from the arithmetic and control unit 10 (the means is not limited, for example, displayed on a display unit of an operation panel of the apparatus). Can be detected and displayed.

[0030]

As described above, according to the present invention,
Based on the result of detecting the image density on the photoreceptor, the image density is controlled, and the human and time burdens associated with this control can be reduced, and stable image density control can be performed.

Further, the above-described control process is executed at the time of replacement with a new photosensitive member, at an arbitrary judgment by a user, or at a fixed period set arbitrarily.
By controlling the image density, and furthermore, when the result obtained after the control of the image density falls below the stored image density information of the allowable limit, it is determined that the life of the photosensitive member has been reached and displayed, so that it is always stable. There is an effect that an image density can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram schematically illustrating an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram illustrating an image forming apparatus according to an embodiment of the present invention.

FIG. 3 is a graph showing a relationship between an image density and a charging potential in a charging unit according to the embodiment of the present invention.

FIG. 4 is a graph showing a relationship between an image density and a developing bias potential in a developing unit according to the embodiment of the present invention.

FIG. 5 is a graph showing the relationship between image density and exposure energy in an exposure unit according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Power supply means 2 Charging means 3 Photoconductor 4 Exposure means 5 Developing means 6 Toner 7 Transfer means 8 Transfer paper 10 Operation control means 11 Storage means 12 Density detection means

Claims (5)

[Claims] A photoconductor, a charging unit for charging the surface of the photoconductor, an exposure unit for forming an electrostatic latent image by exposing the charged surface of the photoconductor, and a toner supply unit for supplying toner to the electrostatic latent image. An image forming apparatus comprising: a developing unit for forming a toner image by transfer; and a transfer unit for transferring the toner image visualized on the photoconductor to a transfer sheet. Density detection means for detecting, storage means for storing image density information serving as a reference and image density information serving as an allowable limit in image density on the photoconductor, and image density information detected by the density detection means. An arithmetic control unit configured to compare and calculate the image density information stored in the storage unit; and an image forming control unit configured to control an image density by changing an image forming condition based on the compared image density difference. thing An image forming apparatus comprising. 2. The image forming apparatus according to claim 1, wherein the control of the image density on the photoconductor is automatically executed when the photoconductor is mounted on the apparatus by replacement with a new photoconductor. 3. The image forming apparatus according to claim 1, wherein the control of the image density on the photoreceptor is arbitrarily executed when the user determines that the image density is necessary. 4. The image forming apparatus according to claim 1, wherein the control of the image density on the photoconductor is performed at an arbitrary fixed cycle. 5. As a result of executing the control of the image density on the photoconductor, when an image density lower than the allowable image density information stored in the storage means is detected, it is determined that the life of the photoconductor is reached. The image forming apparatus according to claim 1, wherein: